JP5829888B2 - Spot welding equipment - Google Patents

Description

  The present invention relates to a spot welding apparatus, and more particularly to a spot welding apparatus that spot welds a member to be welded in a plate assembly in which plate materials having different rigidity are overlapped.

  In general, when joining plate materials such as stacked steel plates, a spot where a large current is passed between the electrodes for a certain period of time while applying pressure between a pair of welding electrodes, and the joint is heated to a substantially melting temperature and joined. Welding is widely performed.

  In spot welding, when the applied pressure and energization time by both welding electrodes are constant, the nugget diameter gradually increases as the current increases, but if the current value is excessive, the amount of heat generation increases and molten metal is present between the plate materials. Causes scattering. That is, it causes a reduction in strength as the plate thickness decreases at the joint. On the other hand, when the current is too small, the nugget becomes small and sufficient bonding strength cannot be obtained. In addition, when the applied pressure is small, the contact area between the plate materials is reduced, the current density is increased, and scattering due to overheating is caused. On the other hand, if the applied pressure is too large, the contact area of the joint is increased, the current density is reduced, the heat generation is reduced, the nugget is reduced, and the welding strength is reduced.

  Here, as shown in FIG. 13, spot welding is performed on a member to be welded 100 in which three sheets of a thin plate 101 having low rigidity, a first thick plate 102 and a second thick plate 103 having higher rigidity than the thin plate 101 are overlapped. In the state where the plate members 101, 102, and 103 are in close contact with each other, when the member to be welded 100 is pressed by the movable side electrode 111 and the fixed side electrode 112 and energized by the power source 113, the movable side electrode 111 and The current density in the energization path between the fixed side electrodes 112 is substantially uniform, and a good nugget is formed from the thin plate 101 to the second thick plate 103, so that welding strength can be obtained.

  However, actually, when the member to be welded 100 is pressed by the movable side electrode 111 and the fixed side electrode 112, the thin plate 101 and the first thick plate 102 having low rigidity bend upward, and the thin plate 101 and the first thickness are bent. A gap is generated between the plates 102 and between the first thick plate 102 and the second thick plate 103. In this case, the contact area between the movable electrode 111 and the thin plate 101 is increased by the bending of the thin plate 101, whereas between the thin plate 101 and the first thick plate 102 and between the first thick plate 102 and the second thick plate 103. The contact area of the joint becomes smaller.

  For this reason, the current density between the movable side electrode 111 and the fixed side electrode 112 is higher on the second thick plate 103 side than on the thin plate 101 side, and the first thick plate 102 and the first thick plate 102 are larger than between the thin plate 101 and the first thick plate 102. The amount of heat generated locally between the two thick plates 103 increases. As a result, first, a nugget 105 is formed at the joint between the first thick plate 102 and the second thick plate 103, and the nugget 105 gradually becomes larger and the thin plate 101 and the first thick plate 102 are welded. However, the amount of penetration between the thin plate 101 and the first thick plate 102 is small, the welding strength is unstable, the peeling of the thin plate 101 is a concern, and the welding quality varies. This problem is particularly noticeable because the nugget 105 is less likely to reach between the first thick plate 102 and the thin plate 101 as the first thick plate 102 and the second thick plate 103 are thicker.

  As a countermeasure, for example, there is a spot welding apparatus disclosed in Patent Document 1. In this spot welding apparatus, a spot welding apparatus 120 is mounted on a wrist 116 of a welding robot 115 as shown in FIG. The spot welding gun 120 is moved to each spot position of the member to be welded 100 supported by the clamper 118, and spot welding of the member to be welded 100 is performed.

  The spot welding device 120 includes a base portion 122 supported by a linear guide 121 fixed to a gun support bracket 117 attached to the wrist portion 116 so as to be movable up and down, and a fixed arm 123 extending downward is provided on the base portion 122. The fixed side electrode 124 is provided at the lower end tip of the fixed arm 123. A pressure actuator 126 is mounted on the upper end of the base portion 122, and the movable electrode 125 is attached to the lower end of the rod 127 that moves up and down by the pressure actuator 126. A servo motor 128 is mounted on the upper end of the gun support bracket 117, and the operation of the servo motor 128 causes the base portion 122 to move up and down via a ball screw mechanism.

  Here, in accordance with teaching data stored in advance in a controller (not shown), the pressure FU applied by the movable electrode 125 located on the thin plate 101 side is made smaller than the pressure FL applied by the fixed electrode 124 (FU <FL).

  In order to make the pressure FU applied by the movable electrode 125 smaller than the pressure FL applied by the fixed electrode 124 in this way, first, the base portion 122 is raised by the servo motor 128 to connect the fixed electrode 124 to the lower surface of the member 100 to be welded. The movable side electrode 125 is lowered by the pressure actuator 126 and is brought into contact with the upper surface of the member to be welded 100 for pressurization. Next, the base portion 122 is pushed up by the servo motor 128. As the base portion 122 is pushed up, the pressing force FL of the fixed side electrode 124 is increased by the pushing amount of the base portion 122, and the pressing force FU by the movable side electrode 125 becomes smaller than the pressing force FL by the fixed side electrode 124.

  As a result, when the movable side electrode 125 and the fixed side electrode 124 are energized, the current density at the joint between the thin plate 101 and the first thick plate 102 is increased, and the amount of heat generated is the first thick plate 102 and the second thickness. It increases relative to the amount of heat generated at the joint of the plate 103. Thereby, a good nugget without bias is formed from the thin plate 101 to the second thick plate 103, and the welding strength can be ensured.

JP 2003-251469 A

  According to Patent Document 1, the current density between the thin plate 101 and the first thick plate 102 is relatively increased by making the applied pressure FU on the movable side electrode 125 side smaller than the applied pressure FL of the fixed side electrode 124. The amount of heat generated at the joint between the thin plate 101 and the first thick plate 102 can be secured, the amount of penetration increases, and the welding strength increases.

  However, the member to be welded 100 clamped and held by the clamper 118 is moved between the fixed side electrode 124 and the movable side electrode 125 while the base part 122 is moved and the movable side electrode 125 is moved by the pressure FL of the fixed side electrode 124. In order to reduce the applied pressure FU caused by the above, a large load is required for the clamper 118 that clamps and holds the member to be welded 100. On the other hand, in a state where the clamp position of the member to be welded 100 by the clamp 118 and the welding position are greatly separated, the member to be welded 100 is bent and deformed, and the applied pressure FL by the fixed electrode 124 and the applied pressure FU by the movable electrode 125 vary. It is difficult to secure a stable contact resistance between the thin plate 101 and the first thick plate 102 and a contact resistance between the first thick plate 102 and the second thick plate 103 due to the occurrence of There is a concern that the quality of spot welding may deteriorate due to variations.

  Accordingly, an object of the present invention made in view of such a point is to provide a spot welding apparatus capable of obtaining stable welding quality when spot-welding a member to be welded in a plate assembly in which plate members having different rigidity are overlapped. is there.

The spot welding apparatus according to the first aspect of the present invention that achieves the above object includes a base portion attached to a welding robot, and a member to be welded supported by a distal end portion of a fixed arm having a base end supported by the base portion. The fixed-side electrode to be in contact with, and the movable-side electrode supported on the same axis as the central axis of the fixed-side electrode mounted on the base portion with an electrode arm interposed therebetween, and the top end of the movable-side electrode as the welded member A pressure actuator that abuts and cooperates with the top end of the fixed-side electrode so as to sandwich the member to be welded and apply a pressurizing force and a retraction position that is separated from the member to be welded; and A sub-pressurizing unit that applies a sub-pressurizing force adjacent to the fixed side electrode to the member to be welded, the movable side electrode contacting the member to be welded and the movable side electrode facing the movable side electrode; Abutting the welded member In a spot welding apparatus that sandwiches and pressurizes the member to be welded by the fixed-side electrode and the sub-pressurizing application means, and conducts spot welding by energizing the movable-side electrode and the fixed-side electrode in the sandwiched and pressurized state. The sub-pressure applying means includes a sub-pressure applying actuator and a predetermined sub-pressure applied to the member to be welded that contacts the top end of the fixed-side electrode at the central axis extending direction position by the sub-pressure applying actuator. A sub-pressurizing unit having a sub-pressurizing unit for imparting the sub-pressurizing unit, and a sub-pressurizing unit for biasing the sub-pressurizing unit in a direction in which the sub-pressurizing unit protrudes from the top end of the fixed electrode A sub-pressurizing application unit positioning unit including a sub-pressure applying unit position fixing unit that selectively fixes and releases the position of the biasing unit and the sub-pressurizing unit at a position in the central axis direction corresponding to the top of the fixed electrode. And features that To.

According to this, the member to be welded is sandwiched between the fixed side electrode and the movable side electrode while the auxiliary pressure part is fixed at the position in the central axial direction corresponding to the top of the fixed side electrode, and the pressure is applied by the pressure actuator. By applying, the pressure applied by the movable electrode is applied to the member to be welded, and the pressure applied by the fixed side electrode and the sub pressure applied by the sub pressure applying unit by the sub pressure applying actuator are applied to the member to be welded. The pressure applied by the electrode is smaller than the pressure applied by the movable electrode. Thereby, the favorable welding of the to-be-welded member which piled up the plate member from which rigidity differs is obtained.

  On the other hand, when the length of the fixed side electrode is shortened by, for example, electrode polishing, the relative position between the top end of the fixed side electrode and the sub-pressurizing portion is displaced, and the pressing force of the fixed side electrode and the auxiliary pressure with respect to the pressing force of the movable side electrode are shifted. There is concern that the balance of the sub-pressurizing force by the pressurizing part may be affected.

Here, when the fixing of the auxiliary pressure applying part by the auxiliary pressure applying part positioning part is released, the auxiliary pressure applying part urging means causes the auxiliary pressure applying part to protrude from the top end of the fixed side electrode. Energize. A member provided separately from the spot welding device in a state where the fixing of the sub-pressurizing unit by the sub-pressurizing application positioning unit is released, for example, an electrode position adjusting member, a movable side electrode, a fixed side electrode, and a sub-pressurizing unit The sub-pressurizing part moves relatively against the sub-pressurizing application urging means, and the top end of the fixed-side electrode and the sub-pressurizing part are both in contact with the electrode position adjusting member and fixed on the fixed side. The sub-pressurization part with respect to the top end of the electrode is moved and adjusted. In this adjusted state, the sub-pressurization applying part is fixed by the sub-pressurization applying part fixing means, so that the pressing force of the movable side electrode is balanced with the pressing force of the fixed-side electrode and the sub-pressurizing part of the sub-pressurizing unit. It can be maintained in the state of the period, and stable and good spot welding quality can be maintained.

  That is, when displacement of the top end of the fixed side electrode occurs, the fixing of the sub pressure applying part by the sub pressure applying part fixing means is released, and the electrode position is adjusted by the movable side electrode, the fixed side electrode and the sub pressure part. The relative position between the top end of the fixed-side electrode and the sub-pressure applying portion can be adjusted by a simple operation of holding and pressing the member and fixing the sub-pressure applying portion again by the sub-pressure applying portion fixing means.

  According to a second aspect of the present invention, in the spot welding apparatus according to the first aspect, the sub-pressure applying unit includes a sub-pressure applying arm that supports the sub-pressure unit at a tip, and the sub-pressure applying unit is provided. An electrode position search plate is provided which is fixed to the application arm and has a planar electrode detection unit corresponding to the position in the central axis extending direction at the tip of the auxiliary pressure unit.

  According to this, the positioning of the spot welding device with respect to the electrode position adjusting member can be easily performed by contacting the search plate and the sub pressure portion with the electrode position adjusting member, etc., and the fixed side electrode, the sub pressure portion and the electrode position plate The electrode position adjusting member is sandwiched and pressed between the electrode detection unit and the movable electrode, and the top end of the fixed electrode and the sub pressurizing unit can be easily adjusted, and the load acts on the sub pressurizing unit. Can be reduced.

  According to a third aspect of the present invention, in the spot welding apparatus according to the first or second aspect, the sub-pressure application unit includes a sub-pressure application arm that supports the sub-pressure unit at a tip thereof. The pressurizing application arm includes a sub-pressurizing unit position search plate having a sub-pressurizing unit detecting unit.

  According to this, the displacement amount of the stationary electrode can be detected by detecting the movement amount of the sub-pressurizing portion position search plate. For example, when spot welding of a member to be welded, the welding robot is operated in advance, and the sub pressure member detection part of the sub pressure member position search plate is brought into contact with the electrode position adjusting member, and the position of the spot welding device at this time is set to the initial welding position. The auxiliary pressurizing part position is stored in the welding robot controller, etc., and the welding robot is operated again after spot welding or electrode polishing, and the auxiliary pressurizing part detection part of the sub pressurizing part position search plate is brought into contact with the electrode position adjusting member. The position of the spot welding apparatus with the lever is set as the post-displacement sub-pressurizing unit position, and the displacement amount of the fixed electrode can be calculated from the phase difference between the initial sub-pressing unit position and the post-displacement sub-pressing unit position measured in advance.

According to the present invention, the member to be welded is sandwiched between the fixed side electrode and the movable side electrode in a state where the auxiliary pressure portion is fixed at the central axial direction position corresponding to the top portion of the fixed side electrode, and the movable side is moved by the pressure actuator. By applying pressure with the electrode, the pressure applied by the movable electrode is applied to the welded member, and the pressure applied by the fixed electrode and the secondary pressure applied from the sub-pressurizing unit by the sub-pressure applying actuator are applied to the welded member. Thus, the pressure applied by the fixed electrode can be made smaller than the pressure applied by the movable electrode, and the welding quality for the member to be welded is improved.

  On the other hand, when the length of the fixed-side electrode is displaced by, for example, electrode polishing, another member, for example, an electrode position adjusting member, is released in a state where the fixing of the sub-pressure applying unit by the sub-pressure applying unit positioning unit is released. When the movable side electrode, the fixed side electrode, and the sub-pressurizing unit are sandwiched and pressurized, the top end of the fixed side electrode and the sub-pressurizing unit both come into contact with the electrode position adjusting member, and a sub-pressurizing application portion for the top end of the fixed electrode is provided. It is adjusted to the initial state, and in this adjusted state, the auxiliary pressure applying part is fixed by the auxiliary pressure applying part fixing means, so that the pressurizing force can be maintained in the intended state, and stable and good spot welding quality can be maintained. .

It is a block diagram of the spot welding apparatus in 1st Embodiment. It is a figure which shows the principal part. It is explanatory drawing of an operation | movement outline | summary. It is a figure which shows an operation | movement outline typically. It is adjustment operation explanatory drawing of a sub pressurization provision means. It is explanatory drawing which shows the relative position of the stationary-side electrode and receiving part in a sub pressurization part position adjustment process. It is a block diagram of the spot welding apparatus in 2nd Embodiment. It is a principal part perspective view which shows the outline | summary of the VIII part of FIG. It is a block diagram of the spot welding apparatus in 3rd Embodiment. It is a principal part perspective view which shows the outline | summary of the X section of FIG. It is a block diagram of the spot welding apparatus in 4th Embodiment. It is a principal part perspective view which shows the principal part of X11 part of FIG. It is explanatory drawing which shows the outline | summary of the conventional spot welding. It is explanatory drawing which shows the outline | summary of the conventional spot welding.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a configuration diagram of a spot welding apparatus, FIG. 2 is a diagram showing a main part, FIG. 3 is an explanatory diagram of an outline of operation, FIG. 4 is an illustrative diagram of an outline of operation, and FIG. Operation explanatory drawing, FIG. 6 is explanatory drawing which shows the relative position of the stationary-side electrode and a sub pressurization part in a sub pressurization part position adjustment process. In the description of the spot welding apparatus, for convenience, the upper and lower parts in FIG. 1 are referred to as the upper and lower parts in the spot welding apparatus.

  Prior to the description of the spot welding apparatus 1, the member to be welded 100 will be described with reference to FIG. The member to be welded 100 is obtained by stacking thin plates on one of two stacked thick plates, for example, a thin plate 101 having lower rigidity in order from the lower side, a first thick plate 102 and a second thick plate 103 having higher rigidity than the thin plate 101. It is comprised by the board set of 3 piles which piled up.

  The spot welding apparatus 1 is supported by a wrist portion attached to an arm tip portion of a welding robot such as an articulated robot via an equalizer unit 2 and is configured to be movable in a three-dimensional direction by the welding robot.

  The spot welding device 1 includes a base portion 3 including a device mounting bracket 4 and a pair of gun brackets 5 that are attached to a wrist portion of a welding robot via an equalizer unit 2. The device mounting bracket 4 is formed in a U-shaped cross section having a mounting base portion 4A connected to the equalizer unit 2 and a pair of gun mounting portions 4B which are bent from both sides of the mounting base portion 4A and face each other. The gun bracket 5 is attached to face each gun attachment portion 4B. The fixed arm 10, the pressure actuator 14, and the welding transformer 53 are attached to the opposing gun bracket 5.

  The fixed arm 10 has a base end portion 10A extending in the horizontal direction by being bent in an L shape from the base end with a substantially T-shaped cross section in which the base ends are spanned and coupled to the end portions of both gun brackets 5. A substantially C-shape having a vertical portion 10B extending downward from the distal end of the proximal end portion 10A and a distal end portion 10C extending from the distal end of the vertical portion 10B so as to face the proximal end portion 10A. It is formed in a shape. The fixed-side electrode 12 is mounted on the electrode holding portion 11 formed at the tip of the tip portion 10C with the top end 12a facing upward.

  The pressurizing actuator 14 has a linear motion portion 16 constituted by a servo motor 15 and a ball screw feeding mechanism, and the rod of the linear motion portion 16 moves up and down by the operation of the servo motor 15. An electrode arm 18 is provided at the lower end of the rod of the linear motion portion 16, and a movable side electrode 19 is provided at the tip of the electrode arm 18 coaxially with the fixed side electrode 12, that is, on the central axis L. Thereby, the retracted position where the movable side electrode 19 is separated from the fixed side electrode 12 by the operation of the pressurizing actuator 14, and the pressurizing position where the member to be welded 100 is clamped and pressed in cooperation with the fixed side electrode 12. Move between.

  In addition, the fixed arm 10 has a sub-pressurizing force close to a position adjacent to the fixed-side electrode 12, that is, a welding position, to the member to be welded 100 to which a pressing force is applied by the fixed-side electrode 12 and the movable-side electrode 19. A sub-pressurizing application means 20 for applying the above is provided.

  As shown in FIGS. 1 and 2, the auxiliary pressure applying means 20 includes a support bracket 21 that is supported by the vertical portion 10 </ b> B of the fixed arm 10, a sub pressure unit positioning unit 30 that is supported by the support bracket 21, and a sub pressure. It is comprised by the provision part 40.

  The support bracket 21 is attached to the vertical portion 10B of the fixed arm 10 by a fixing means such as a U-bolt 22a, and extends from the mounting portion 22 along the tip portion 10C of the fixed arm 10 and has a central axis L. And a base portion 23 having a substantially rectangular plate shape in cross section. A first through hole 24 </ b> A and a second through hole 24 </ b> B that are parallel to the central axis L and penetrate from the upper surface to the lower surface are formed in the base 23.

  The sub-pressurizing unit positioning unit 30 penetrates and holds the first shaft 31 penetrating the first through hole 24A on the upper surface of the base 23 so as to be movable in the axial direction, and selectively fixes and holds the first shaft 31 at an arbitrary moving position. A slide brake unit 34 having a mechanism is provided. For example, the slide brake unit 34 is switched between unlocking that allows axial movement of the first shaft 31 by air supply from an air device and locking that prevents movement of the first shaft 31 by stopping air supply. This slide brake unit 34 constitutes a sub-pressurizing application portion position fixing means.

  In addition, the flange portion is fitted to one end of the second through hole 24B, and the second shaft 32 is fitted and held so as to be movable in the axial direction in a cylindrical shape that protrudes from the upper surface through the second through hole 24B. A linear bush 35 is provided.

  A spring pressing plate 36 is installed and fixed between the top end of the first shaft 31 and the top end of the second shaft 32, and is wound around the first shaft 31 between the top end of the slide brake unit 34 and the spring pressing plate 36. A spring 37A is attached. Similarly, a spring 37 </ b> B wound around the second shaft 32 is mounted between the top end of the linear bush 35 and the spring holding plate 36. The springs 37 </ b> A and 37 </ b> B constitute sub-pressurizing application unit urging means that urges the sub-pressure application unit 40 upward via the first shaft 31 and the second shaft 32.

  A sub pressurizing application unit 40 including an electrode position search plate 41 and a sub pressurizing application arm 45 serving as electrode position detecting means is disposed below the base 23 of the support bracket 21. The electrode position search plate 41 is a plate having a rectangular upper surface and a lower surface that can come into contact with the lower surface of the base 23 of the support bracket 21 and extending along the lower surface of the base 23. Protrudes from the tip 23a of the base 23, and the first through-hole 42A and the second shaft 32 through which the first shaft 31 is fitted coaxially with the first through-hole 24A and the second through-hole 24B of the base 23 pass through. The second through hole 42 </ b> B is formed and is fixed to the first shaft 31 and the second shaft 32. The range of the upper surface 41 </ b> A of the tip portion 41 a of the electrode position search plate 41 is the electrode detection unit 43.

  The sub-pressurizing application arm 45 extends in the direction of the central axis L through a base portion 46A that extends along the lower surface of the electrode position search plate 41 and can be contacted, and a step portion that is bent downward from the tip of the base portion 46A. A first through-hole having a U-shaped cross section having an upper surface 46 having an extending tip 46B and side surfaces 47 bent downward along both sides of the upper surface 46, and the first shaft 31 is fitted into the base 46A. A second through hole 48B through which the hole 48A and the second shaft 32 penetrate is formed. A cylindrical sub-pressurizing portion 49 that protrudes upward coaxially with the central axis L and allows the fixed electrode 12 to pass therethrough is provided at the distal end portion 46B. The tip 49a of the sub-pressurizing portion 49 has the same height in the height of the extension surface of the electrode detecting portion 43, that is, in the direction of the central axis L in a state where the sub-pressurizing application arm 45 is in contact with the lower surface of the electrode position search plate 41. Set to the position.

  A spring pressing plate 51 is installed and fixed between the distal ends of the first shaft 31 and the second shaft 32 protruding from the first through hole 48A and the second through hole 48B of the sub-pressurizing application arm 45, and the base 46A. A spring 52A wound around the first shaft 31 and a spring 52B wound around the second shaft 32 are mounted between the spring holding plate 51 and the spring holding plate 51. The sub-pressurization applying arm 45 is pressed and biased to the lower surface side of the electrode search plate 41 by the springs 52A and 52B, and the sub-pressurizing portion 49 is biased upward via the sub-pressurizing applying arm 45. Constructing the application actuator. A sub-pressurizing force Fα that biases the sub-pressurizing portion 49 upward by the spring force of the springs 52A and 52B, that is, the biasing force, is set.

  One output terminal of the welding transformer 53 serving as a power source is connected to the fixed side electrode 12 through the bus bar and the fixed arm 10 so as to be energized, and the other output terminal is connected to the movable side electrode 19 through the bus bar and the electrode arm 18 and the like. Is connected to be energized.

  On the other hand, as shown in FIG. 5, an electrode detection unit 43 and a sub-pressurization unit 49 formed on the electrode search plate 41 of the sub-pressurization applying unit 20 provided in the spot welding apparatus 1 in the operation area of the welding robot. A sub-pressurizing unit including a rectangular cross-sectional electrode position adjusting member 56 provided with a flat search surface 57 with which the front end 49a can abut and a movable side electrode abutment surface 58 with which the top end 19a of the movable side electrode 19 can abut. A part position adjusting device 55 is arranged. In addition, an electrode polishing machine 59 is disposed in the sub-pressurizing unit position adjusting device 55. The electrode polishing machine 59 includes, for example, a blade having a pair of upper and lower blade surfaces and a drive device that rotationally drives the blade.

  A welding robot controller (not shown) stores teaching data of the welding robot, and the teaching data includes an operation program for sequentially spot welding the welding spot positions of the member to be welded 100 and each welding spot, that is, the welding position. The position and attitude of the spot welding apparatus 1 in FIG. The welding controller (not shown) includes an operation program of the welding apparatus 1 and an operation control of the pressure actuator, the welding transformer, and the auxiliary pressure applying means 20.

  Next, the operation of the spot welding apparatus 1 will be described.

(Spot welding process)
In spot welding of the member to be welded 100, the top end 12a of the fixed side electrode 12 that contacts the thin plate 101 and the tip 49a of the sub-pressurizing portion 49 are adjusted to the same height so that the slide brake unit 34 of the sub-pressurizing applying means 20 is adjusted. Keep locked. When the slide brake unit 34 is in a locked state, the first shaft 31 and the second shaft 32 are held in a fixed state, and the sub pressure applying arm 45 is pressed against the electrode position search plate 41 by the sub pressure Fα by the springs 52A and 52B. Rush.

  The welding robot controller operates the welding robot in a state where the fixed side electrode 12 and the movable side electrode 19 are separated from each other, and moves the spot welding apparatus 1 to the striking position of the member to be welded 100 according to a preset program. 3, the spot welding apparatus 1 is positioned by abutting the top end 12 a of the fixed electrode 12 provided on the fixed arm 10 and the tip 49 a of the sub-pressurizing portion 49 against the lower surface of the member to be welded 100, that is, the thin plate 101. To do. In a state where the spot welding apparatus 1 is positioned at the welding position, the top end 12a of the fixed electrode 12 and the sub-pressurizing portion 49 are formed on the lower surface of the thin plate 101 of the member to be welded 100 as schematically shown in FIG. The top end 19a of the movable side electrode 19 faces the second thick plate 103 with a gap.

  Next, the movable side electrode 19 is moved in the direction of the pressurization position by the operation of the servo motor 15 of the pressurization actuator 14 in a state where the sub pressurization portion 49 and the fixed side electrode 12 are in contact with the member to be welded 100. The welded member 100 is welded between the top end 19a of the movable side electrode 19 and the top end 12a of the fixed side electrode 12 as shown in FIG. 4C. Pressurize the part.

  In this case, as schematically shown in FIG. 4C, the pressure applied by the pressure actuator 14 acts on the movable side electrode 19 via the electrode arm 18 and the like, and via the base 3 and the fixed arm 10. In addition to acting on the fixed-side electrode 12, the biasing force of the springs 52 </ b> A and 52 </ b> B acts on the sub-pressurizing unit 49 via the sub-pressurizing imparting arm 45 in the sub-pressurizing application unit 20 and acts on the second thick plate 103. The sum of the pressing force FU by the movable electrode 19 and the pressing force FL by the fixed electrode 12 acting on the thin plate 101 and the sub pressing force Fα by the sub pressurizing unit 49 are equal (FU = FL + Fα). As a result, the member to be welded 100 has a pressing force FU of the movable side electrode 19 acting on the second thick plate 103 side from above, and a pressing force FL and a sub-pressing force of the fixed side electrode 12 acting on the thin plate 101 side from below. The portion 49 is held and held in a stable state by the auxiliary pressure Fα of the portion 49.

  On the other hand, a welding force FU of the second thick plate 103 is applied from the movable side electrode 19 to the welded portion of the member to be welded 100, and the pressing force FL from the fixed side electrode 12 and the auxiliary pressure from the auxiliary pressure unit 49 are applied to the thin plate 101. Since the pressure Fα is applied, the applied pressure FL acting on the thin plate 101 from the fixed side electrode 12 is a magnitude obtained by subtracting the sub applied pressure Fα by the sub pressurizing unit 49 from the applied pressure FU by the movable side electrode 19. Pressure is applied (FL = FU−Fα).

  In this way, the pressing force FL of the fixed side electrode 12 positioned on the thin plate 101 side is made smaller than the pressing force FU of the movable side electrode 19 positioned on the second thick plate 103 side (FL <FU). The contact resistance between the first thick plate 102 and the first thick plate 102 increases, and the contact resistance between the first thick plate 102 and the second thick plate 103 decreases.

  Next, in this state, the welding transformer 53 performs welding for a predetermined time between the movable electrode 19 and the fixed electrode 12 for welding. When the movable side electrode 19 and the fixed side electrode 12 are energized, the contact resistance between the thin plate 101 and the first thick plate 102 is relatively large, the current density is increased, and the current density is increased. And the second thick plate 103 are kept small in contact resistance. As a result, the amount of heat generated at the joint between the thin plate 101 and the first thick plate 102 is relatively increased with respect to the amount of heat generated at the joint between the first thick plate 102 and the second thick plate 103, and the second from the thin plate 101. A good nugget with no uneven current density is formed over the thick plate 103, and the welding strength of the thin plate 101 can be ensured.

  After this welding is completed, the movable side electrode 19 is moved from the pressurizing position to the retracted position by the operation of the pressurizing actuator 14, and welding is performed by the movable side electrode 19, the fixed side electrode 12, and the auxiliary pressurizing unit 49. The clamping of the member 100 is released.

  Next, the welding robot is operated to retract the spot welding apparatus 1 from the spot position of the welded member 100 and move to the spot position of the next welded member 100.

  When such spot welding is repeatedly performed, the top end 12a of the fixed side electrode 12 and the top end 19a of the movable side electrode 19 that are in contact with the member to be welded 100 are worn or deformed. Since the wear and deformed top end shapes of the fixed electrode 12 and the movable side electrode 19 affect the current density of the current path and determine the welding quality, the top end shapes of the fixed side electrode 12 and the movable side electrode 19 are deformed. An electrode polishing step is performed for each number of hitting points set in advance by polishing before and adjusting the shape of the top end of the electrode.

(Electrode polishing process)
In the spot welding apparatus 1, for example, the slide brake unit 34 of the auxiliary pressure applying means 20 is switched to unlock, and the electrode position search plate 41 is pushed downward against the springs 37 </ b> A and 37 </ b> B to fix the fixed side electrode 12. The top end 12a of the stationary electrode 12 is protruded from the sub-pressurizing portion 49, and the slide brake unit 34 is locked at that position to hold the top end 12a of the stationary electrode 12 in a state of projecting from the sub-pressurizing portion 49.

  Then, the spot welding apparatus 1 is moved to the position of the electrode polishing machine 59 so that the fixed side electrode 12 and the movable side electrode 19 are opposed to each other through the cutting tool, and the movable electrode 19 is moved in the direction of the pressure position by the pressure actuator 14. Then, the top end 12a of the fixed side electrode 12 and the top end 19a of the movable side electrode 19 are pressed against the cutting tool so as to be sandwiched from above and below, and in this state, the top end 19a of the movable side electrode 19 and the fixed side electrode 12 are rotated. The top end 12a is shaped. After the electrode shaping is completed, the movable side electrode 19 is moved to the retracted position by the pressurizing actuator 14 to separate the fixed side electrode 12 and the movable side electrode 19 from the cutting tool, and the spot welding apparatus 1 is retracted from the electrode polishing machine 59.

  Here, as the electrode is polished, the top end 12a of the fixed side electrode 12 and the top end 19a of the movable side electrode 19 are ground so that the effective length of the fixed side electrode 12 is shortened. 49, the relative position of the tip 49a with respect to the tip 49a is displaced, which affects the balance of the pressure FU of the movable electrode 19 when the spot welding is performed, the pressure FL of the fixed electrode 12, and the sub pressure Fα of the auxiliary pressure member 49. Therefore, the relative position of the sub-pressurizing unit 49 with respect to the top end 12a of the fixed electrode 12 is adjusted to an intended state.

(Sub-pressure part position adjustment process)
In adjusting the position of the sub-pressurizing unit 49, the slide brake unit 34 of the sub-pressurizing means 20 is switched to unlocking. The unlocking of the first shaft 31 by the slide brake unit 34 is released along with this unlocking, and the first force is applied by the urging forces of the springs 37A and 37B mounted between the slide brake unit 34 and the linear bush 35 and the spring holding plate 36. The shaft 31 and the second shaft 32 are pushed upward, and the electrode position search plate 41 comes into contact with the lower surface of the base 23 of the support bracket 21 and stops.

  When the electrode position search plate 41 is in contact with the base 23 of the support bracket 21, the secondary pressure is applied by the urging force of the springs 52 </ b> A and 52 </ b> B mounted between the spring holding plate 51 and the secondary pressure application arm 45. As shown in FIG. 6A, the arm 45 is held at a position pressed against the lower surface of the electrode position search plate 41, and the tip 49a of the sub-pressurizing portion 49 provided on the sub-pressurizing application arm 45 is as shown in FIG. It will be in the state which protruded from the top end 12a of the fixed electrode 12 shortened by electrode polishing.

  With the slide brake unit 34 of the sub-pressurizing application means 20 maintained in the unlocked state, the spot welding device 1 is moved to the sub-pressurizing portion position adjusting device 55 side, and as shown in FIG. The electrode detector 43 and the tip 49a of the sub-pressurizer 49 are both brought into contact with the search surface 57 of the electrode position adjusting member 56 from below and positioned at the adjustment position. Here, the electrode position search plate 41 and the auxiliary pressure member 49 are brought into contact with the search surface 57 of the electrode position adjusting member 56 so that the spot welding apparatus 1 can be easily positioned with respect to the electrode position adjusting member 56 and the auxiliary pressure member. The load on 49 is reduced.

  In a state where the spot welding apparatus 1 is positioned at the adjustment position, as shown in FIG. 6B, the electrode detection portion 43 of the electrode position search plate 41 and the tip 49 a of the sub-pressing portion 49 are connected to the electrode position adjustment member 56. While contacting the search surface 57 together, the top end 19a of the movable electrode 19 faces the movable electrode contact surface 58 with a gap. Further, the fixed side electrode 12 is maintained in a state facing the search surface 57 with a gap.

  Next, the sub-pressurizing portion 49 and the electrode detecting portion 43 of the electrode search plate 41 are in contact with the search surface 57 of the electrode position adjusting member 56 from the lower side by the operation of the servo motor 15 of the pressure actuator 14 on the movable side. The electrode 19 is moved in the direction of the pressurizing position, and the top end 19a of the movable electrode 19 is brought into contact with the movable electrode contact surface 58 of the electrode position adjusting member 56 as shown in FIG.

  Subsequently, pressure is applied to the electrode position adjusting member 56 from above by the movable electrode 19 via the electrode arm 18 and the like by the operation of the pressure actuator 14. As the pressing force is applied by the movable side electrode 19, the base portion 3 and the fixed arm 10 are moved upward by the reaction force from the electrode position adjusting member 56 applied to the movable side electrode 19, and the fixed side electrode 12 is sub-added. As shown in FIG. 6 (d), the top end 12 a of the fixed side electrode 12 comes into contact with the search surface 57 of the electrode position adjusting member 56 and the movable side electrode 19 and the fixed side electrode 12 move the electrode position. The adjustment member 56 is clamped.

  As the fixed side electrode 12 moves upward, the electrode search plate 41 and the sub-pressurizing portion 49 that are in contact with the search surface 57 of the electrode position adjusting member 56 and are prevented from moving upward are relative to the base 23 of the support bracket 21. The first shaft 31 and the second shaft 32, which are relatively pushed down and coupled to the electrode search plate 41, are guided by the slide brake unit 34 and the linear bush 35 against the springs 37A and 37B and descend from the support bracket 21. The electrode search plate 41 is separated.

  The tip 49a of the sub-pressurizing portion 49, the top end 12a of the fixed side electrode 12, and the electrode detecting portion 43 of the electrode search plate 41 are all in contact with the search surface 57 of the electrode position adjusting member 56, and the top end 19a of the movable side electrode 19 is used. Is in contact with the movable electrode contact surface 58 of the electrode position adjusting member 56, that is, the electrode position adjusting member 56 is sandwiched between the movable electrode 19, the fixed electrode 12, the auxiliary pressure unit 49, and the movable electrode 19. The slide brake unit 34 is locked in the state.

  The movement of the first shaft 31 and the second shaft 32 is restricted by the lock of the slide brake unit 34, and the electrode search plate 41 is fixedly held at the positions. The top end 12a of the fixed side electrode 12 and the tip of the sub pressurizing portion 49 are fixed. 49a is relatively held at the same position in the central axis L direction. That is, the displacement between the top end 12a of the fixed electrode 12 and the tip 49a of the sub-pressurizing portion 49 generated by electrode polishing is adjusted to an expected state in which the displacement is relatively the same in the central axis L direction.

  Thereafter, the movable side electrode 19 is moved to the retracted position by the pressure actuator 14 to release the holding of the electrode position adjusting member 56 by the movable side electrode 19, the fixed side electrode 12, and the auxiliary pressure unit 49, and the welding robot. Is operated to retract the spot welding device 1 from the sub-pressurizing portion position adjusting device 55 and the position adjustment of the sub-pressing portion 49 is completed.

  Therefore, when the top end 12a of the fixed side electrode 12 is displaced due to electrode polishing or the like, the slide brake unit 34 of the sub-pressurizing means 20 is switched to the unlocked state, and the movable actuator 19 and the fixed side electrode are switched by the pressure actuator 14. The fixed electrode 12 and the sub-pressurizing unit 49 are adjusted to the intended state by a simple operation of locking the slide brake unit 34 again in a state where the electrode position adjusting member 56 is sandwiched and pressurized by the twelve and sub-pressurizing units 49. Can do.

  The sub-pressurizing application unit 40 includes a supporting bracket 21 supported by the fixed arm 10, a first shaft 31 and a second shaft 32 that pass through the base portion 22 of the supporting bracket 21, and a sub-pressurizing unit 49 at the distal end portion 46 </ b> B. The auxiliary pressure applying arm 45 and the springs 52 </ b> A and 52 </ b> B are provided, and the auxiliary pressure part positioning unit 30 includes a slide brake unit 34 that selectively fixes the first shaft 31, and a spring 37 </ b> A. It can be formed with a simple structure such as 37B.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a configuration diagram of the spot welding apparatus, and FIG. 8 is a perspective view of a main part of the VIII portion of FIG. 7 and 8, the same reference numerals are given to the portions corresponding to those in FIGS. 1 to 6, and detailed description thereof will be omitted.

  The spot welding apparatus 1 includes a base portion 3 that is attached to a wrist portion of a welding robot via an equalizer unit 2, and a fixed arm 10, a pressure actuator 14, and a welding transformer 53 are attached and supported to a gun bracket 5 of the base portion 3. Is done.

  The fixed arm 10 is provided with sub-pressure applying means 60. The sub-pressure applying unit 60 includes a sub-pressure applying unit positioning unit 61 and a sub-pressure applying unit 64.

  The sub-pressurizing part positioning part 61 penetrates and holds the shaft 62 movably in the axial direction parallel to the central axis L at the upper part of the base end portion 10A of the fixed arm 10, and also fixes and holds the shaft 62 at an arbitrary moving position. The slide brake unit 34 is provided. A spring pressing plate is provided at the top end of the shaft 62, and a spring 37 serving as a sub-pressurizing applying portion urging means is provided between the spring pressing plate and the slide brake unit 34.

  The sub-pressurizing application unit 64 includes a guide rail 66 provided on the vertical portion 10B of the fixed arm 10, and has an upper surface 65A and a side surface 65B supported at the base end by a slider 67 slidably supported by the guide rail 66. It has a sub-pressurizing application arm 65 having a substantially U-shaped cross section and extending along the tip portion 10C. A through-hole 65C is opened on the base end side of the upper surface 65A of the sub-pressurizing application arm 65, and a sub-pressurizing portion 49 is provided at the tip.

  As shown in FIG. 8, a spring pressing plate 68 is provided at the tip of the shaft 62 that passes through the through-hole 65 </ b> C of the auxiliary pressure applying arm 65, and the auxiliary pressure is applied between the spring pressing plate 68 and the auxiliary pressure applying arm 65. A spring 52 serving as an application actuator is arranged. The spring 52 has a larger spring force than the spring 37, and the biasing force of the spring 52 is set by the sub-pressurizing unit 49 via the sub-pressurizing application arm 65.

  The electrode position search plate 41 is disposed along the upper surface 65 </ b> A of the sub-pressure applying arm 65. In the electrode position search plate 41, the shaft 62 passes through the through hole at the base end, and is fixed to the sub-pressurizing application arm 65 by the rotation stop pin 41p. The upper surface 41A of the tip portion 41a of the electrode position search plate 41 becomes the electrode detector 43, and the tip 49a of the sub-pressurizing portion 49 is set at the same height position as the electrode detector 43.

  The spot welding apparatus 1 configured as described above is configured to fix the fixed-side electrode 12 and the sub-pressurizing unit 49 in a state where the shaft 62 is fixedly held by the lock of the slide brake unit 34 when welding the member to be welded 100. The spot welding apparatus 1 is positioned in contact with the 100 thin plates 101. Further, the movable electrode 19 is moved in the direction of the pressure position by the pressurizing actuator 14, and the member to be welded 100 is sandwiched and pressed between the top end 19 a of the movable side electrode 19 and the top end 12 a of the fixed side electrode 12.

  As a result, the pressure applied by the pressure actuator 14 acts on the movable side electrode 19 and the fixed side electrode 12, and the urging force of the spring 52 acts on the sub-pressurization unit 49 via the sub-pressurization application arm 65. The applied pressure FL of the fixed side electrode 12 positioned on the 101 side is smaller than the applied pressure FU of the movable side electrode 19 positioned on the second thick plate 103 side. In this state, the current is welded between the movable side electrode 19 and the fixed side electrode 12.

  In the electrode polishing, the slide brake unit 34 of the auxiliary pressure applying means 60 is switched to the unlocked state, the auxiliary pressure member 49 is pushed by the biasing force of the spring 52, and the top end 12a of the fixed electrode 12 is moved to the auxiliary pressure member 49. The slide brake unit 34 is locked again at that position. Then, similarly to the first embodiment, the movable side electrode 19 and the fixed side electrode 12 are shaped by the electrode polishing machine 59.

  To adjust the position of the sub-pressurizing unit 49, the slide brake unit 34 is switched to the unlocked state, and the shaft 62 is pushed upward by the urging force of the spring 37, so that the sub-pressurizing application arm 65 and the electrode position search plate 41 are raised. As a result, the tip 49 a of the sub-pressurizing portion 49 protrudes from the top end 12 a of the fixed electrode 12.

  When the slide brake unit 34 is unlocked, the electrode detection portion 43 formed on the electrode search plate 41 and the tip 49a of the auxiliary pressure portion 49 are both brought into contact with the search surface 57 of the electrode position adjusting member 56 from below, and By actuating the servo motor 15, the movable electrode 19 is moved in the direction of the pressure position, and the electrode position adjusting member 56 is held between the movable electrode 19 and the fixed electrode 12. In this state, the slide brake unit 34 is locked. Due to the lock of the slide brake unit 34, the shaft 62 is fixed in this position and the sub-pressurizing application arm 65 and the electrode search plate 41 supported by the shaft 62 are held, and the top end 12a of the fixed-side electrode 12 and the sub-pressurizing are held. The tip 49a of the portion 49 is adjusted to the desired state.

  Accordingly, when displacement occurs at the top end 12a of the fixed side electrode 12 due to electrode polishing or the like, the slide brake unit 34 of the auxiliary pressure applying means 60 is unlocked, and the movable actuator 19 and the fixed side are operated by the operation of the pressure actuator 14. The top end 12a of the stationary electrode 12 and the tip 49a of the receiving portion 49 are in an expected state by a simple operation of locking the slide brake unit 34 again with the electrode position adjusting member 56 held and pressed by the electrode 12 and the receiving portion 49. Adjusted to

  Compared to the first embodiment, the slide brake unit 34 or the like is not provided in the fixed arm 10, so that a work space in the fixed arm 10 is ensured, and the restriction on the work range of the welding apparatus 1 is eased. Is done.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a configuration diagram of the spot welding apparatus, and FIG. 10 is a perspective view of a main part of the portion X in FIG. 9 and 10, the same reference numerals are given to the portions corresponding to those in FIGS. 1 to 7, and detailed description thereof will be omitted.

  The spot welding device 1 includes a base portion 3 including a device mounting bracket 4 and a gun bracket 5 that are attached to a wrist portion of a welding robot via an equalizer unit 2. The device mounting bracket 4 is formed in a U-shaped cross section having a mounting base portion 4A and a pair of gun mounting portions 4B connected to the equalizer unit 2, and in a box shape having a bottom portion 4C serving as a sub-pressure applying means mounting support portion. It is formed. The fixed arm 10, the pressure actuator 14, and the welding transformer 53 are attached and supported by the gun bracket 5 attached to each gun attaching portion 4B.

  Sub-pressure applying means 70 is provided on the device mounting bracket 4 and the fixed arm 10. The sub-pressurizing application unit 70 includes a sub-pressurizing unit positioning unit 71 and a sub-pressurizing unit 72 that are attached to the bottom portion 4 </ b> C of the device mounting bracket 41.

  A search rod fixing bracket (not shown) is attached to the lower surface of the bottom portion 4C of the device mounting bracket 41 in an overlapping manner. A first through hole and a second through hole (not shown) are formed in the bottom portion 4C and the search rod fixing bracket.

  The sub pressurizing part positioning part 71 slidably holds the first shaft 31 penetrating the first through hole on the upper surface of the bottom part 4C of the apparatus mounting bracket 41 and also holds the slide brake unit 34 that holds it at an arbitrary moving position. Have. Further, a linear bush 35 that fits and holds the second shaft 32 penetrating the second through hole is provided.

  A spring pressing plate 36 is installed between the top ends of the first shaft 31 and the second shaft 32, and springs 37A and 37B are mounted between the slide brake unit 34, the spring pressing plate 36, and the linear bush 35 and the spring pressing plate 36. The The springs 37 </ b> A and 37 </ b> B constitute sub-pressure applying unit urging means that urges the sub-pressure applying unit 72 upward.

  A rectangular sub-pressure applying arm mounting base 73 having a through hole through which the first shaft 31 and the second shaft 32 penetrate is disposed below the bottom 4C of the device mounting bracket 4 so as to be movable. A spring pressing plate 51 is installed between the tips of the second shaft 32. The first shaft 31 and the springs 52A and 52B wound around the second shaft 32 are mounted between the auxiliary pressure applying arm mounting bracket 73 and the spring pressing plate 51. The sub-pressurizing force Fα by the sub-pressurizing unit 49 is set by the urging force of the springs 52A and 52B.

  The sub-pressurizing application arm 75 has a base end coupled to the sub-pressure application arm mounting base 73 and a pair of plate-like side portions 75B extending along the fixed arm 10, and both sides of each side portion 75B. Joined and formed in an L shape having an upper surface 75A facing the tip portion 10C and the vertical portion 10B of the fixed arm 10. A cylindrical bush 76 is disposed in a through-hole that opens to the base end side of the upper surface 75A, and a sub-pressurizing portion 49 is provided on the tip end side. Sub-pressurization is applied by the spring pressing plate 51, the springs 52A and 52B, the sub-pressurizing application arm mounting base 73, the sub-pressure application arm 74, and the sub-pressurization unit 49 installed on the first shaft 31 and the second shaft 32. Part 72 is configured.

  On the other hand, the upper end is connected to the bottom portion 4C of the device bracket 4 through the through hole formed in the base end portion 10A of the fixed arm 10, and the lower end passes through the bush 76 provided on the sub-pressurizing application arm 75. A search rod 78 is coupled to the portion 10C.

  The electrode position search plate 41 is disposed on the upper surface 75 </ b> A of the sub pressure applying arm 75. The electrode position search plate 41 is formed at the base end, the search rod 78 passes through the through hole 42, and is fixed to the sub-pressure applying arm 75 by the rotation stop pin 41p. The upper surface of the tip portion 41 a of the electrode position search plate 41 becomes the electrode detection unit 43, and the upper end 49 a of the sub-pressurization unit 49 is set to a height corresponding to the electrode detection unit 43.

  The auxiliary pressure applying means 70 configured as described above is configured such that the auxiliary pressure applying arm mounting bracket 73 is urged upward by the springs 52 </ b> A and 52 </ b> B when the slide brake unit 34 is locked. The combined sub pressure applying arm 75 is urged upward along the search rod 58. Further, when the slide brake unit 34 is unlocked, the sub-pressure applying arm 75 is biased upward by the springs 37A and 37B.

  The spot welding apparatus 1 configured as described above is configured to fix the fixed electrode 12 and the sub-pressurizing unit 49 in the state where the first shaft 31 is fixedly held by the lock of the slide brake unit 34 in spot welding of the member 100 to be welded. The spot welding apparatus 1 in contact with the thin plate 101 of the member to be welded 100 is positioned. In this state, the movable side electrode 19 is moved in the direction of the pressure position by the operation of the servo motor 15 of the pressure actuator 14, and the member to be welded is between the top end 19 a of the movable side electrode 19 and the top end 12 a of the fixed side electrode 12. 100 is sandwiched and pressurized.

  As a result, the pressurizing force of the pressurizing actuator 14 acts on the movable side electrode 19 and the fixed side electrode 12, and the urging force of the springs 52 </ b> A and 52 </ b> B acts on the sub pressurizing unit 49 via the subpressurizing application arm 75. Thus, the pressing force FL of the fixed side electrode 12 positioned on the thin plate 101 side is smaller than the pressing force FU of the movable side electrode 19 positioned on the second thick plate 103 side. In this state, the current is welded between the movable side electrode 19 and the fixed side electrode 12.

  In electrode polishing, the slide brake unit 34 of the auxiliary pressure applying means 70 is switched to unlocked, the top end 12a of the fixed side electrode 12 is protruded from the auxiliary pressure portion 49, the slide brake unit 34 is locked again, and the fixed side is fixed. The top portion 12 a of the electrode 12 is held in a state protruding from the sub-pressurizing portion 49. Then, similarly to the first embodiment, the movable side electrode 19 and the fixed side electrode 12 are shaped by the electrode polishing machine 59.

  The position adjustment of the sub-pressurizing unit 49 unlocks the slide brake unit 34. As a result, the first shaft 31 and the second shaft 32 are pushed by the urging force of the springs 37A and 37B, the control pressurizing application arm 75 and the electrode position search plate 41 are raised, and the tip 49a of the sub pressurizing portion 49 is fixed. The electrode 12 protrudes from the top end 12a.

  When the slide brake unit 34 is unlocked, the electrode detection unit 43 and the tip 49a of the auxiliary pressure unit 49 formed on the upper surface 41A of the electrode search plate 41 are brought into contact with the search surface 57 of the electrode position adjusting member 56, In addition, the movable side electrode 19 is moved in the direction of the pressurizing position by the operation of the servo motor 15, and the electrode position adjusting member 56 is sandwiched between the movable side electrode 19 and the fixed side electrode 12. In this state, the slide brake unit 34 is locked. By switching the slide brake unit 34 to the locked state, the movement of the first shaft 31 and the second shaft 32 is restricted, and the auxiliary pressure applying arm 75 and the electrode search plate 41 supported via the springs 52A and 52B and the like. Hold in the desired state.

  Accordingly, when the top end 12a of the fixed side electrode 12 is displaced due to electrode polishing or the like, the slide brake unit 34 of the sub-pressurizing means 70 is switched to the unlocked state, and the movable actuator 19 is fixed by the operation of the pressure actuator 14. In a state where the electrode position adjusting member 56 is sandwiched and pressed by the side electrode 12 and the sub-pressurizing unit 49, the fixed side electrode 12 and the sub-pressurizing unit 49 are brought into an intended state by a simple operation of locking the slide brake unit 34 again. Can be adjusted.

  Compared to the first embodiment, the slide brake unit 34 or the like is not provided in the fixed arm 10, so that a work space in the fixed arm 10 is ensured, and the restriction on the work range of the welding apparatus 1 is eased. Is done.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS.

  FIG. 11 is a configuration diagram of the spot welding apparatus, and FIG. 12 is a perspective view of a main part of the XII portion of FIG. In FIGS. 11 and 12, parts corresponding to those in FIGS. 1 to 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The spot welding device 1 includes a base portion 3 including a device mounting bracket 4 and a gun bracket 5 that are attached to a wrist portion of a welding robot via an equalizer unit 2. The device mounting bracket 4 is formed in a U-shaped cross section having a mounting base portion 4A connected to the equalizer unit 2 and a pair of gun mounting portions 4B, and further has a rectangular plate-shaped bottom portion 4C serving as a sub-pressure applying means supporting portion. It is formed in a box shape.

  The device mounting bracket 4 and the fixed arm 10 are provided with a sub-pressure applying means 80. The sub-pressurizing application means 80 includes an elevating positioning unit 81 and a sub-pressure applying unit 82 that are attached to the bottom 4 </ b> C of the device mounting bracket 4.

  The lifting / lowering positioning portion 81 includes a slide brake unit 34 that movably penetrates and holds the first shaft 31 penetrating the first through hole in the bottom portion 4 </ b> C of the device mounting bracket 4 and holds it at an arbitrary movement position. A linear bushing 35 is provided for fittingly holding the second shaft 32 penetrating the second through hole so as to be movable.

  A spring pressing plate 36 is installed between the top ends of the first shaft 31 and the second shaft 32, and springs 37A and 37B are provided between the slide brake unit 34 and the spring pressing plate 36 and between the linear bush 35 and the spring pressing plate 36. Is installed. The springs 37 </ b> A and 37 </ b> B constitute sub-pressure applying unit urging means that urges the control pressure applying unit 82 upward.

  A search provided in the rectangular secondary pressure applying arm mounting bracket 83 and the secondary pressure applying arm mounting bracket 83 having through holes through which the first shaft 31 and the second shaft 32 pass below the bottom portion 4C of the device mounting bracket 4. A plate fixing plate 84 is movably disposed, and a spring pressing plate 51 is installed between the tip of the first shaft 31 and the tip of the second shaft 32.

  A spring 52A wound around the first shaft 31 and a spring 52B wound around the second shaft 32 are mounted between the auxiliary pressure applying arm mounting bracket 83 and the spring pressing plate 51. By the springs 52 </ b> A and 52 </ b> B, a sub pressurizing force Fα by the sub pressurizing unit 49 is set through the subpressurizing application arm 85.

  The sub-pressure applying arm 85 has a base end coupled to the sub-pressure applying arm mounting bracket 83 and a pair of side portions 85B extending along both sides of the fixed arm 10, and is joined and fixed to each side portion 85B. The arm 10 is formed in an L shape having an upper surface 85A facing the upper surface of the tip portion 10C and the vertical portion 10B. A sub-pressurizing portion 49 is provided on the upper surface 85 </ b> A on the tip side of the sub-pressurizing application arm 85. In addition, a support roller 86 is provided on the upper surface 85A so as to roll in contact with the straight portion 10B of the fixed arm 10.

  Further, a sub pressurizing portion position search plate 87 is provided on the search plate fixing plate 84 provided on the sub pressurizing application arm mounting bracket 83. The sub-pressurizing portion position search plate 87 has a base portion 87A attached to the search plate fixing plate 84 and a search portion 87B that bends outward from the lower edge of the base portion 87A. The upper surface becomes the sub-pressurizing part detecting part 88 having a planar shape.

  A spring pressing plate 51, springs 52A and 52B, a sub-pressurizing arm mounting bracket 85, a sub-pressurizing portion 49, and a sub-pressurizing portion position search that are installed between the tip of the first shaft 31 and the tip of the second shaft 32. A sub-pressure applying unit 82 is configured by the plate 87 and the like.

  The auxiliary pressure applying means 80 configured as described above is configured such that the auxiliary pressure applying arm mounting bracket 83 is biased upward by the springs 52 </ b> A and 52 </ b> B when the slide brake unit 34 is locked, The sub-pressure applying arm 85 to which the base end is coupled is biased upward. Further, when the slide brake unit 34 is unlocked, the sub-pressurizing application arm 85 is urged upward by the springs 37A and 37B. In conjunction with the movement of the sub-pressure applying arm 85, the sub-pressure portion 49 and the sub-pressure portion position search plate 87 move in parallel with the central axis L.

  In the spot welding apparatus 1 configured as described above, when spot welding is performed on the member 100 to be welded, the welding robot controller operates the welding robot, moves the spot welding apparatus 1 to the sub-pressurizing portion position adjustment apparatus 55, and performs spot welding. The receiving portion detecting portion 88 of the sub pressure portion position search plate 87 provided in the apparatus 1 is brought into contact with the movable electrode contact surface 58 of the electrode position adjusting member 56. The position of the spot welding apparatus 1 in a state where the sub-pressurizing part detecting part 88 is in contact with the movable electrode contact surface 58 is stored as the initial receiving part position P0 in the teaching data of the robot controller.

  Next, the spot welding apparatus 1 is moved to the striking position of the member to be welded 100, and the fixed side electrode 12 and the sub-pressurizing portion 49 provided on the fixed arm 10 are brought into contact with the thin plate 101 of the member to be welded 100, By actuating the pressure actuator 14, the movable electrode 19 is moved in the direction of the pressurizing position and is brought into pressure contact with the second thick plate 103, thereby sandwiching the member to be welded 100 and applying pressure.

  Here, the pressure applied by the pressure actuator 14 acts on the movable side electrode 19 and the fixed side electrode 12, and the urging force of the springs 52 </ b> A and 52 </ b> B acts on the sub pressure unit 49 via the sub pressure application arm 63. The applied pressure FL of the fixed side electrode 12 located on the thin plate 101 side is smaller than the applied pressure FU of the movable side electrode 19 on the second thick plate 103 side, and in this state, between the movable side electrode 19 and the fixed side electrode 12 Energize and weld.

  In electrode polishing, for example, the slide brake unit 34 of the sub-pressurizing application means 80 is switched to unlock, the top end 14a of the fixed electrode 14 is protruded from the sub-pressurizing portion 49, and the slide brake unit 34 is moved at that position. The top 14 a of the fixed side electrode 14 is locked and held in a state of protruding from the sub pressure unit 49. Then, similarly to the first embodiment, the movable side electrode 19 and the fixed side electrode 12 are shaped by the electrode polishing machine 59.

  To adjust the position of the auxiliary pressure part after electrode polishing, the slide brake unit 34 is switched to the unlocked state, and the first shaft 31 and the second shaft 32 are pushed upward by the urging force of the springs 37A and 37B. The application arm 85 rises, and the upper end 49 a of the sub-pressurizing unit 49 is protruded from the top end 12 a of the fixed electrode 12.

  When the slide brake unit 34 is unlocked, the movable electrode 19 is moved in the direction of the pressure position by the pressure actuator 14, and the electrode position adjusting member 56 is held between the movable electrode 19 and the fixed electrode 12.

  As a result, the slide brake unit 34 is locked in a state where the tip 49 a of the sub-pressurizing unit 49 and the top end 12 a of the fixed electrode 12 and the top end 19 a of the movable electrode 19 are both in contact with the electrode position adjusting member 56. By the lock of the slide brake unit 34, the movement of the first shaft 31 and the second shaft 32 is restricted, and the sub pressurizing unit pressurizing arm 85 is adjusted to an intended state.

  After adjusting the position of the sub-pressurizing unit, the welding robot controller operates the welding robot to move the spot welding apparatus 1 so that the sub-pressurizing unit detecting unit 88 of the sub-pressurizing unit position search plate 87 is moved to the sub-pressurizing unit. It contacts the movable electrode contact surface 58 of the electrode position adjusting member 56 of the position adjusting device 55.

  The position of the spot welding device 1 in a state in which the sub-pressurizing portion detection portion 88 of the sub-pressurizing portion position search plate 87 is in contact with the movable electrode contact surface 58 is stored in the teaching data as a post-displacement sub-pressurizing portion position P1. To do. The phase difference LI (L1 = P0−P1) in the central axis L direction between the post-displacement sub-pressurizing portion position P1 and the previously measured initial sub-pressurizing portion position P0 is the shortened displacement amount of the fixed side electrode 12 due to electrode polishing or the like. Yes, this is the position adjustment amount of the sub-pressurizing unit 49 accompanying electrode polishing. As a result, the fixed side electrode 12 can be easily managed, the displacement of the sub-pressurizing portion 49 can be easily grasped, and the stable adjustment of the sub-pressurizing force Fα can be facilitated to ensure stable spot welding quality.

  In addition, this invention is not limited to the said embodiment, A various change can be made in the range which does not deviate from the meaning of invention. For example, although the sub-pressurizing portion 49 is formed in a cylindrical shape in each of the above-described embodiments, it may be formed by arranging a half-like or arcuate plate material in a cylindrical shape, or by a protrusion. it can. Also in the first to third embodiments, as in the fourth embodiment, the sub-pressurizing portion position search plate having the sub-pressurizing portion detecting portion is disposed on the sub-pressurizing application arm. be able to.

DESCRIPTION OF SYMBOLS 1 Spot welding apparatus 3 Base part 10 Fixed arm 12 Fixed side electrode 12a Top end 14 Pressurization actuator 19 Movable side electrode 19a Top end 20, 60, 70, 80 Sub pressurization provision means 30, 61, 71, 81 Sub pressurization provision part Positioning part 34 Slide brake unit (sub-pressurizing part position fixing means)
37, 37A, 37B Spring (sub-pressurizing application portion biasing means)
40, 64, 72, 82 Sub-pressure applying portion 41 Electrode position search plate (electrode position detecting means)
43 Electrode detection unit 45, 65, 75, 85 Sub pressure applying arm 49 Sub pressure unit 52, 52A, 52B Spring (Sub pressure applying actuator)
87 Sub pressurization part position search plate

Claims (3)

A base part attached to the welding robot;
A fixed-side electrode that is supported by a distal end portion of a fixed arm whose base end is supported by the base portion and abuts against a member to be welded;
The fixed side electrode is mounted on the base portion, supports the movable side electrode coaxially with the center axis of the fixed side electrode via an electrode arm, and abuts the top end of the movable side electrode against the member to be welded. A pressurizing actuator that moves between a pressurizing position that sandwiches the welded member in cooperation with the top end of the welded member and applies a pressing force and a retracted position that is separated from the welded member;
Sub-pressurizing application means for applying a sub-pressurizing force adjacent to the fixed electrode to the welded member,
The movable member that is in contact with the member to be welded, the fixed electrode that is in contact with the member to be welded so as to face the movable side electrode, and the auxiliary pressure applying unit sandwich and pressurize the member to be welded, In a spot welding apparatus for performing spot welding by energizing between the movable side electrode and the fixed side electrode in a sandwiched pressure state,
The sub-pressurizing means is
A sub-pressure applying actuator and a sub-pressure applying portion that applies a predetermined sub-pressurizing force to the member to be welded that is in contact with the top end of the fixed-side electrode at the center axis extending direction position by the sub-pressure applying actuator. A sub-pressure applying part;
A sub-pressurizing application portion for urging and applying the sub-pressure applying portion in a direction in which the sub-pressure applying portion protrudes from the top end of the fixed-side electrode, and a position of the sub-pressure applying portion are selectively set on the fixed side. A spot welding apparatus, comprising: a sub-pressure applying unit positioning unit including a sub-pressure applying unit position fixing means for fixing and releasing the fixing at a position in the central axial direction corresponding to the top of the electrode . The sub-pressure applying unit includes a sub-pressure applying arm that supports the sub-pressure unit at a tip,
An electrode position search plate, which is fixed to the sub-pressurizing application arm and has a planar electrode detector corresponding to a position in the direction of extension of the central axis at the tip of the sub-pressurizing unit. Item 10. The spot welding apparatus according to Item 1. The sub-pressure applying unit includes a sub-pressure applying arm that supports the sub-pressure unit at a tip,
The spot welding apparatus according to claim 1, wherein the sub-pressurizing application arm includes a sub-pressurizing portion position search plate having a sub-pressurizing portion detecting portion.

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