JP2014094441A - Screwdriver tool for removing machine screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screwdriver tool for removing a machine screw, for surely removing the machine screw, by making a biting-in edge bite in the peripheral edge of a machine screw head part, even in the machine screw in a state of being shaven in a cone shape when an operation groove is crushed.SOLUTION: The screwdriver tool aims to remove the machine screw 10 in which the machine screw head part 11 is formed in an outer convex curved shape or a part of the machine screw head part 11 projects from a fastening seat. The tip of a driver shaft 2 of the screwdriver tool is provided with a cylindrical operation part 5 for operating the machine screw head part 11 for loosening. The biting-in edge 22 biting in the peripheral edge of a surface of the machine screw head part 11 is provided along the center axis of the driver shaft 2 in three places or more of an inner peripheral surface 21 of the operation part 5. The driver shaft 2 is struck in its center axis direction in a state of allowing the lower end of the biting-in edge 22 to abut on the peripheral edge of the surface of the machine screw head part 11, and the machine screw 10 is operated for loosening by making the biting-in edge 22 bite in the peripheral edge of the surface of the machine screw head part 11.

Description

  The present invention relates to a screwdriver tool applied to a manual screwdriver or an electric screwdriver, and more particularly to a screwdriver tool suitable for removing a screw whose operation groove provided on a screw head is crushed.

  The present applicant has previously proposed this type of screwdriver (Patent Document 1). There, rib-like projections and V-shaped troughs are alternately formed in the operating portion at the tip of the driver shaft. The rib-shaped protrusions are formed in a trapezoidal cross section with a first valley surface, a second valley surface, and a rib peripheral surface connecting the protruding ends of both valley surfaces. The operation edge that cuts into the damaged recess is provided at the ridge line portion between the first valley surface and the rib peripheral surface, and the edge is bitten by the biting angle with respect to the central axis of the driver shaft, thereby biting the lower end of the operation edge. The starting end is positioned on the upper side of the rotational direction and is looser than the end on the upper end side of the edge. At the time of use, the tip of the operating portion is applied to the damaged recess of the screw head, and the upper surface of the driver's grip is struck with a hammer so that the starting end of the bite and the operating edge are bitten into the damaged recess. In this state, the screw can be removed from the screw hole by rotating the screwdriver in the screw loosening direction.

  A similar screwdriver tool can also be found in US Pat. There, a screw extraction part is provided at the tip of the screw removal bit, and a tapered tip is provided at the end. A groove is formed on the peripheral surface of the screw extraction part from the end of the pointed tip to the base end of the screw extraction part, and a drill-shaped cutting edge is formed at the intersection of the inner surface of the groove and the outer peripheral surface of the screw extraction part. A notch that is formed and nullifies the cutting action of the cutting blade is formed in the middle. When using, fix the screwing bit to the chuck of the electric screwdriver, and rotate the screwing bit in the direction of loosening the screw with the tip pointed at the center of the screw head (screw head). Cut the blade into the cross hole in the screw head. When the biting depth of the screw removal part reaches the notch part, the cutting action by the cutting blade is stopped, and the inclined surface of the notch part is caught by the inner surface of the cross hole, so the screw is rotated in the direction of loosening the screw. Can be removed by manipulation.

  The screwdriver of the present invention causes the operation edge to bite into the surface of the screw head and removes the screw whose operation groove is crushed. A similar screwdriver can be found in Patent Document 3. There, a round cylindrical head is provided at the tip of the shaft, and four protrusions are provided in a cross shape on the end surface of the head. The projection is provided with an acute point, and the point is bitten into the surface of the screw head to remove the screw. In use, after attaching the shaft to the shock driver, with the protrusion circumscribing the surface of the screw head, hit the shock driver's proximal end with a hammer and bite the tip into the screw head at the same time. Remove the screw by applying a force in the loosening direction.

  As a similar screwdriver tool, Patent Document 4 discloses a screwdriver tool in which a large number of edges are formed on the inner surface of a socket wrench-shaped socket. Specifically, square holes and mortar-shaped operation holes are provided above and below the inner surface of the socket, and a large number of edges are formed in a circular shape on the inner surface of the operation holes. The apex angle of the edge having a triangular cross section is 60 degrees, and the edge ridge line is twisted 30 degrees with respect to the center axis of the socket. However, the screwdriver of Patent Document 4 is mainly used for removing a hexagon bolt or a hexagon nut that has been crushed and rounded at a corner.

JP 2012-157913 (paragraph numbers 0029 to 0031, FIG. 1) JP 2006-102894 A (paragraph numbers 0016 to 0019, FIG. 1) JP 2003-266327 A (paragraph number 0014, FIG. 1) US Pat. No. 5,551,320

  In the screwdriver of Patent Document 1, even when the damaged concave portion has been scraped into a mortar shape, the biting start end and the operation edge provided in the operating portion are bitten into the damaged concave portion, and the screw is moved in the screw loosening direction. Can be rotated. However, since the operation edge is bitten into the damaged recess of the screw head that has been crushed, there is a difficulty in that the moment in the loosening direction applied to the screw is small. This is because the radial distance (moment arm) from the biting position of the operation edge to the center position of the screw head is small.

  The screwdriver of Patent Document 2 is provided with a conical thread extraction part at the lower end of a shaft having a hexagonal cross section, and a cutting edge is formed at the tip thereof, so that it is compared with the screwdriver tool of Patent Document 1. Therefore, it is inevitable that the cutting edge bites closer to the center position side of the screw head. Therefore, even when removing a screw having a small nominal diameter, a sufficient loosening force cannot be applied to the screw unless a larger force is applied. Such a problem can be solved by using an electric tool having a large driving torque as a driving source. However, when using a power tool as the drive source, the rise of the drive torque at the start-up is abrupt, so excessive drive torque acts on the screwing bit, and the damaged recess is cut into a bowl shape with a cutting blade. It is often done. One cutting blade provided in the screw extraction part is bitten into the screw head, so that the drive torque is concentrated on the cutting blade, which is one of the factors that cause the damaged recess to be cut into a bowl shape by the cutting blade. . In the case of a screw having a large nominal diameter, the cutting edge is often chipped.

  The screwdriver of Patent Document 3 is provided with four protrusions in a cross shape on the cylindrical end surface of a round cylindrical head. On the other hand, most screw heads are formed in an upwardly convex curved surface. For this reason, in a state where the four protrusions are circumscribed on the surface of the curved screw head, what is received by the screw head is limited to a part of the protrusion. Therefore, even if the shock driver is struck with a hammer, the protrusions will only bite into the opening edge of the damaged recess, and the protrusions will bite into the screw heads enough to transmit the torque in the direction of screw loosening. Can not.

  The screwdriver of patent document 4 is suitable for the use which removes the hexagon bolt or hexagon nut by which the corner part was crushed and rounded. However, the edge of the socket's inner surface is in contact with multiple locations on the peripheral surface of the hexagonal bolt with rounded corners, so that the moment in the loosening direction acts on the peripheral surface of the hexagonal bolt. However, it is difficult to bite the edge of the edge into the circular screw head. Further, as shown in FIG. 1, when the screw receiving hole for receiving the screw head is provided in a state of being greatly recessed from the surface to be fastened, the diameter of the screw receiving hole is slightly larger than the diameter of the screw head. Therefore, it is difficult to insert the socket into the screw receiving hole.

  As described above, the conventional screw removal tool for screw removal can remove the screw depending on the damage state of the operation hole of the screw head, but there is room for improvement in that the application range is narrow and the reliability is lacking. The present inventors have observed a failure state of a screw whose operation groove is crushed, studied a method for removing this type of screw, and re-developed a tool structure for reliably removing this type of screw. As a result of the study, the present invention has been proposed. In particular, even when the operation hole is broken into a mortar shape and the fastening part is rusted or stuck to the fastening seat, only the screw head maintains the original shape. It is.

The object of the present invention is to remove the countersunk screw by allowing the biting edge to bite into the periphery of the screw head even when the operation groove of the screw head is crushed or the damaged recess is scraped into a mortar shape. It is an object of the present invention to provide a screwdriver for screw removal that can more reliably remove various screws.
An object of the present invention is to provide a screw capable of accurately removing various screws except for a countersunk screw by causing a biting edge to bite into the periphery of the screw head even when the screw receiving hole is formed in a recess. It is to provide a screwdriver for removal.

  In the screwdriver according to the present invention, the screw head 11 is formed in an outwardly convex curved shape, or the screw 10 in which a part of the screw head 11 protrudes from the fastening seat is to be removed. The screwdriver tool is provided at the tip of the driver shaft 2 in a state where a cylindrical operation portion 5 for loosening the screw head 11 is opened downward. A biting edge 22 that cuts into the peripheral edge of the surface of the screw head 11 is provided on the inner peripheral surface 21 of the operation unit 5 along the central axis of the driver shaft 2. In a state where the lower end of the biting edge 22 is in contact with the peripheral edge of the surface of the screw head 11, the driver shaft 2 is struck in the direction of the central axis to cause the biting edge 22 to bite into the peripheral edge of the screw head 11. It is characterized by that.

  The biting edge 22 is formed in a rib shape by intersecting a plurality of edge side surfaces 23 projecting inward of the inner surface of the inner peripheral surface 21 of the operation portion 5 inside the inner peripheral surface 21. When the diameter of the inner peripheral surface 21 of the operation unit 5 is D1, the diameter of the screw head 11 is D2, and the virtual circle diameter passing through the ridge line 24 of the biting edge 22 is D3, the diameter D2 of the screw head 11 is used as a reference. The inner peripheral surface 21 and the biting edge 22 are configured to satisfy the formula (D1> D2> D3).

  Three or more biting edges 22 are formed at equal intervals in the circumferential direction on the inner peripheral surface 21 of the operation unit 5.

  A tip slope 25 is formed at the lower end of the biting edge 22. As shown in FIG. 1, the tip inclined surface 25 is formed in a state of being inclined downward from the base end side of the biting edge 22 over the ridge line 24.

  A tip slope 25 is formed at the lower end of the biting edge 22. As shown in FIG. 8, the tip slope 25 is formed by a pair of inclined surfaces 32 that are continuous with the lower ends of the pair of edge side surfaces 23. The lower ridge line 33 formed at the intersection of the pair of inclined surfaces 32 is formed so as to be inclined upward from the inner peripheral surface 21 side toward the ridge line 24.

  As shown in FIG. 12, the lower end surface 38 of the biting edge 22 is formed as a flat surface, and the minute relief surface 39 is formed at the intersection corner of the lower end surface 38 and the ridge line 24.

  A virtual cylindrical surface passing through the ridge line 24 of the biting edge 22 provided on the inner peripheral surface 21 of the operation unit 5 is formed in a tapered shape that tapers upward toward the driver shaft 2 side. The biting edge 22 and the ridge line 24 are inclined with respect to the central axis of the driver shaft 2, and the biting start end 26 at the lower end of the ridge line 24 is positioned on the upper side of the screw loosening direction from the upper end of the ridge line 24.

  In the screwdriver of the present invention, the cylindrical operation portion 5 is provided at the tip of the driver shaft 2, and the biting edge 22 is provided on the inner peripheral surface 21 along the central axis of the driver shaft 2. When using a screwdriver, the lower end of the biting edge 22 is brought into contact with the periphery of the screw head 11, and in this state, the driver shaft 2 is struck in the direction of the central axis, and the biting edge 22 is moved to the screw head 11. Encroach on the periphery. Since the biting edge 22 and the screw head 11 in this state are engaged via a groove 27 formed in the screw head 11, the rotational force of the driver shaft 2 is applied via the biting edge 22 and the groove 27. By transmitting to the screw head 11, the screw 10 can be removed by rotating in the loosening direction.

  Therefore, according to the screwdriver tool of the present invention, even if the operation groove 12 of the screw head 11 is crushed or the damaged recess 13 is scraped into a mortar shape, the biting edge 22 is inserted into the screw head 11. The various screws 10 except for the countersunk screws can be removed more reliably. Further, since the biting edge 22 is bitten into the periphery of the screw head 11 to remove the screw, even if the first screw removal fails, the contact position of the biting edge 22 with respect to the screw head 11 is set in the circumferential direction. By shifting, the screw removing operation can be repeatedly executed. Therefore, the screw 10 can be removed more reliably than a conventional screwdriver of this type. Further, even when the screw receiving hole 15 is formed in a recess on the surface of the fastening object 16, after inserting the operation portion 5 into the screw receiving hole 15, the driver shaft 2 is struck to insert the biting edge 22 into the screw head 11. By biting into the periphery, the various screws 10 accommodated in the screw accommodating hole 15 can be accurately removed.

  When a plurality of edge side surfaces 23 projecting inward of the inner peripheral surface 21 of the operation portion 5 are crossed inside the inner peripheral surface 21 to form the biting edge 22 in a rib shape, the structural strength of the biting edge 22 is ensured. However, the biting action on the screw head 11 can be sufficiently exerted. Further, with reference to the diameter D2 of the screw head 11, the diameter D1 of the inner peripheral surface 21 and the imaginary circle diameter D3 passing through the ridge line 24 of the biting edge 22 satisfy the formula (D1> D2> D3). By comprising, the biting edge 22 can be reliably bited into the periphery of the screw head 11 to be removed.

  When three or more biting edges 22 are formed at equal intervals in the circumferential direction on the inner peripheral surface 21 of the operation unit 5, the opposing biting edges 22 are in the process of biting into the screw head 11. Alternatively, adjacent edges bite into the screw head 11 while exerting a centering action. Therefore, each biting edge 22 is bitten substantially uniformly with respect to the screw head 11, and the biting edge 22 and the screw head 11 can be firmly integrated via the groove 27. The rotational force can be reliably transmitted to the screw head 11.

  If the tip inclined surface 25 inclined downward is formed at the lower end of the biting edge 22, the angle of the biting start end 26 is set to an acute angle, and the biting operation of the biting start end 26 and the biting edge 22 with respect to the screw head 11 is performed more smoothly. be able to. Further, the wall of the screw head 11 cut by the biting start end 26 can be pushed outward in the radial direction of the screw head 11 while being guided by the tip slope 25. Accordingly, the biting resistance of the biting edge 22 with respect to the screw head 11 can be reduced, and the biting edge 22 can be bited into the periphery of the screw head 11 with a smaller force, so that the screw removal operation can be easily performed.

  When the tip inclined surface 25 provided at the lower end of the biting edge 22 is formed by a pair of inclined surfaces 32, and the lower ridge line 33 formed at the intersection of both inclined surfaces 32 is inclined upward toward the ridge line 24, the pair of inclined surfaces 32. Thus, the V-shaped leading groove 34 can be formed so as to separate the wall of the screw head 11. Furthermore, the biting edge 22 can be bitten into the leading groove 34 to form the V-shaped groove 27. At this time, the meat wall pressed by the pair of inclined surfaces 32 and the biting edge 22 forms the food feeding wall 35 that protrudes outward from the peripheral surface of the screw head 11. Only the radial engagement depth between the biting edge 22 and the screw head 11 can be increased. Therefore, the loosening force applied to the driver shaft 2 can be more accurately transmitted from the biting edge 22 to the screw head 11 to facilitate screw removal work.

  In the screwdriver that makes the lower end surface 38 of the biting edge 22 flat, the wall surface of the screw head 11 is shaved at the lower end surface 38, and the shaved wall wall is forced outward in the radial direction of the screw head 11. And the groove 27 is formed in the screw head 11. In other words, since the groove 27 corresponding to the biting depth in the vertical direction of the biting edge 22 is formed in the screw head 11, the biting edge 22 and the same edge 22 are compared with the case where the tip slope 25 having a downward slope is provided. It is possible to increase the contact area of the groove 27 that is in close contact with the surface. Therefore, the loosening force applied to the driver shaft 2 can be more accurately transmitted from the biting edge 22 to the screw head 11 to facilitate screw removal work. The reason why the minute relief surface 39 is formed at the intersection corner of the lower end surface 38 and the ridge line 24 is to prevent the hitting force from being concentrated on the intersection corner and being damaged.

  When the virtual cylindrical surface passing through the ridge line 24 of the biting edge 22 is formed in a tapered shape, the biting depth of the biting edge 22 in the radial direction with respect to the screw head 11, that is, the groove 27 on the peripheral surface of the screw head 11 is formed. The depth can be gradually increased as it approaches the shoulder. Further, the biting start end 26 and the biting edge 22 are obliquely bitten into the meat wall of the screw head 11 by positioning the biting start end 26 at the lower end of the ridge line 24 on the upper side of the ridge line 24 in the screw loosening direction. Thus, the contact area between the biting edge 22 and the groove 27 can be increased. Therefore, as a whole, the engagement strength of the biting edge 22 with the screw head 11 can be increased, and the loosening force applied to the driver shaft 2 can be accurately transmitted to the screw head 11.

It is a vertical front view which shows the use condition of the screwdriver which concerns on Example 1. FIG. 1 is a front view of a screwdriver tool according to Embodiment 1. FIG. It is the vertical front view which fractured | ruptured the operation part of the screwdriver which concerns on Example 1. FIG. It is the sectional view on the AA line in FIG. It is a front view which shows the use preparation state of the screwdriver tool which concerns on Example 1. FIG. It is sectional drawing which shows the modification of the screwdriver tool which concerns on Example 1. FIG. It is a vertical front view which shows the use condition of the screwdriver which concerns on Example 2. FIG. It is a perspective view of the screwdriver tool concerning Example 2. FIG. It is CC sectional view taken on the line in FIG. It is the vertical front view which fractured | ruptured the operation part of the screwdriver which concerns on Example 2. FIG. It is the BB sectional view taken on the line in FIG. It is a vertical front view which shows the use condition of the screwdriver which concerns on Example 3. FIG. It is the vertical front view which fractured | ruptured the operation part of the screwdriver which concerns on Example 3. FIG. It is the DD sectional view taken on the line in FIG. It is the vertical front view which fractured | ruptured the operation part of the screwdriver which concerns on Example 4. FIG. FIG. 9 is a cross-sectional plan view of an operation unit of a screwdriver tool according to a fourth embodiment. It is an expanded view which shows the internal structure of the operation part of the screwdriver which concerns on Example 4. FIG. It is the vertical front view which fractured | ruptured the operation part of the screwdriver which concerns on Example 5. FIG. FIG. 10 is a perspective view of an operation unit in a screwdriver tool according to a fifth embodiment.

First Embodiment FIGS. 1 to 5 show a first embodiment in which the screwdriver according to the present invention is applied to a manual screwdriver. The screwdriver according to the present invention is a screw other than a flat head screw, specifically, a round head screw, a pan head screw, a flat head screw, a round head screw, a truss head screw, a binding head screw, a round head screw. Screws such as machine screws whose screw heads are formed in an outwardly convex curve or whose screws are partially protruding from the fastening seats are to be removed.

  In FIG. 2, the manual driver includes a grip 1, a replaceable driver shaft 2 that can be attached to and detached from the grip 1, a striking body 3 that directly transmits the striking force to the driver shaft 2, and a driver provided at the bottom of the grip 1. The chuck 4 is configured to hold and fix the shaft 2. The driver shaft 2 is made of a turning product made of tool steel, and has a cylindrical operation portion 5 at the tip (lower end). The hitting body 3 is integrally provided with a flange-like hitting portion 6 exposed at the upper end of the grip 1 and a hitting shaft 7 extending below the hitting portion 6, and is fixedly inserted when the grip 1 is formed. When the chuck 4 is pushed toward the grip 1 against a spring (not shown), the holding force of the chuck 4 is released, so that the driver shaft 2 can be attached and detached in this state. Although the driver shaft 2 attached to the grip 1 can slightly move up and down, the upper end of the driver shaft 2 is received by the lower end surface of the hitting shaft 7 in a state in which the operation portion 5 is pressed against the screw head 11 to be removed.

  FIG. 4 shows the screw 10 to be removed. The screw 10 is composed of a pan head screw, and the peripheral wall of the cross-shaped operation groove 12 formed in the center of the screw head 11 is shaved with a driver bit such as an electric screwdriver so that the damaged recess 13 is shaped like a mortar. Indicates the state. The damaged recess 13 is often formed when the screw shaft 14 of the screw 10 is rusted or when the screw head 11 is stuck to the fastening surface of the screw receiving hole 15, and in particular, driving torque. Is easily formed when the screw 10 is removed using a large electric tool. In FIG. 1, reference numeral 16 is an object to be fastened, 17 is an object to be screwed in the screw 10, 18 is an insertion hole for the screw shaft 14, and 19 is a screw hole provided in the screwed object 17. The screw accommodation hole 15 is provided in a state of being greatly recessed from the surface of the fastening object 16, and the diameter thereof is set larger than the diameter of the screw head 11.

  The operation part 5 is formed in a round cylinder shape with a downward opening, and six biting edges 22 are provided on the inner peripheral surface 21 at equal intervals in the circumferential direction. As shown in FIGS. 1 to 3, the biting edge 22 has a pair of edge side surfaces 23 that project obliquely toward the inner surface of the inner peripheral surface 21 of the operation unit 5 from the inner peripheral surface 21 of the operation unit 5. It is formed in a rib shape having a triangular cross section by crossing inside. The angle between the pair of edge side surfaces 23 is 90 degrees, and each edge side surface 23 is uniformly inclined with respect to the inner peripheral surface 21 of the operation unit 5. A ridge line 24 is formed at the top where the two edge side surfaces 23 intersect, but the ridge line 24 is slightly rounded.

  Each of the six biting edges 22 is formed in parallel with the central axis of the driver shaft 2, and a tip slope 25 for promoting biting into the screw head 11 is formed at the lower end of the biting edge 22. . Specifically, as shown in FIG. 1, both the wall of the operation unit 5 and the biting edge 22 are ground in a tapered shape, and the tip slope 25 is inclined downward from the base end of the biting edge 22 over the ridge line 24. Formed as follows. Thus, by providing the tip slope 25, a biting start end 26 is formed at the intersection of the lower end of the tip slope 25 and the ridge line 24.

  As described above, when the tip slope 25 is inclined with respect to the opening plane of the operation portion 5 (the opening edge of the inner peripheral surface 21), the biting start end 26 can be positioned below the lower end of the cylindrical wall of the operation portion 5. In addition, the angle of the biting start end 26, that is, the angle between the ridge line 24 and the tip slope 25 can be made acute. Further, when the biting edge 22 bites into the screw head 11, a component force of a striking reaction force corresponding to the wedge action acts on the tip inclined surface 25, and this component force causes the biting edge 22 to be center axis of the driver shaft 2. Therefore, the biting edge 22 can be effectively bited into the peripheral edge of the screw head 11. In this embodiment, the inclination angle θ1 of the tip inclined surface 25 is 15 degrees, but it is preferable to select it within a range of 5 degrees to 30 degrees. When the inclination angle θ1 is less than 5 degrees, the component force of the striking reaction force acting on the tip inclined surface 25 becomes small, so that the biting action becomes dull. When the inclination angle θ1 exceeds 30 degrees, the biting start edge 26 is easily damaged due to the impact force.

  In order to securely bite the biting edge 22 and the biting start end 26 into the peripheral edge of the surface of the screw head 11, the relationship between the operation unit 5, the screw head 11 and the biting edge 22 is set as follows. When the diameter of the inner peripheral surface 21 of the operation unit 5 is D1, the diameter of the screw head 11 is D2, and the diameter of a virtual circle passing through the ridge line 24 of the biting edge 22 is D3, the inequality (D1> D2> D3) The operation unit 5 and the biting edge 22 are configured so as to satisfy the above. For example, according to the JIS cross-recessed machine screw standard, when the nominal diameter of the screw (pan head screw) 10 is M4, the diameter of the screw head 11 is 7 mm, and the overall height of the screw head 11 is 2 mm. 6 mm. For example, if the diameter D1 of the inner peripheral surface 21 of the operation unit 5 is set to 7.5 mm and the virtual circle diameter D3 passing through the ridge line 24 is set to 6.4 mm based on the diameter of the screw head 11, the above inequality is obtained. It becomes a satisfactory configuration.

  Although it is ideal that the manual screwdriver is individually provided according to the difference in the nominal diameter of the screw 10 or the shape of the screw head 11, it is not always necessary. For example, within the range of the above inequality, if the diameter D3 of the imaginary circle passing through the ridge line 24 of the biting edge 22 is set to be somewhat smaller, not only the screw having a suitable nominal diameter but also the nominal diameter is different. One manual screwdriver can be applied in common to various screws. Further, in most of the screws 10 to be removed having different head shapes, one manual screwdriver can be applied in common if the nominal diameter is the same. In the case of a round screw machine screw, the degree of protrusion of the outer convex curved surface of the screw head is small, so it is preferable to prepare a dedicated manual screwdriver. It can be applied to the screw 10.

  When loosening and operating the screw 10 with a manual screwdriver, the operating portion 5 is inserted into the screw receiving hole 15, and the biting start end 26 of the biting edge 22 is the shoulder of the curved surface of the screw head 11 as shown in FIG. The driver shaft 2 is held vertically while being in contact with. By hitting the hitting portion 6 of the driver with a hammer in this state, an impact acting on the hitting body 3 is transmitted to the driver shaft 2 so that the biting edge 22 is bitten into the screw head 11 as shown in FIG. it can. In the process in which the biting edge 22 bites into the screw head 11, the meat wall of the screw head 11 is shaved by the biting start end 26, and the shaved meat wall is guided by the tip inclined surface 25 and radially outside the screw head 11. Extruded. Further, the meat wall pushed out of the screw head 11 is finally crushed by the tip slope 25 and the lower end surface of the cylindrical wall of the operation unit 5 as shown in FIG. It is plastically deformed.

  In the process in which the biting edge 22 bites into the screw head 11, the six biting start ends 26 bite into the screw head 11 at the same time, and the opposing biting edges 22 and adjacent edges exert a centering action. Therefore, each biting edge 22 is bitten evenly with respect to the screw head 11 to form a groove 27 having a V-shaped cross section on the screw head 11 side, and the biting edge 22 and the screw head 11 are connected to each other. It can be firmly integrated through the groove 27.

  As described above, by rotating the grip 1 to the loose side while the biting edge 22 is bitten into the screw head 11, a large moment of rotation in the loosening direction is applied to the screw 10, and the screw 10 Can be accurately separated from the screwed object 17 and removed from the screw hole 19. This is because the bite arm 22 is bitten into the periphery of the screw head 11 so that the moment arm is about twice that of a conventional screwdriver tool that bites the operation edge into the inner surface of the mortar-shaped damaged recess. This is because it can be made large. Furthermore, the loosening force applied via the six biting edges 22 can be reliably transmitted to the screw head 11 via the groove 27.

  Therefore, according to the screwdriver having the above-described configuration, even if the operation groove 12 of the screw head 11 is crushed or the damaged recess 13 is shaved into a mortar shape, the biting edge 22 is connected to the periphery of the screw head 11. It is possible to remove the various screws 10 more reliably. Further, even when the screw receiving hole 15 is formed in a recess on the surface of the fastening object 16, after the operation portion 5 is inserted into the screw receiving hole 15, the biting edge 22 is struck on the periphery of the screw head 11. The various screws 10 can be removed accurately by entraining them. In the screwdriver according to the first embodiment, the biting edge 22 can be bitten from the shoulder portion of the screw head 11 to the fastening surface, so that the screw head 11 has a large overall height and a small overall height. Even with the screw 10, the biting edge 22 can be accurately bited into the screw head 11 and removed. For example, even if the biting edge 22 is not sufficiently bitten by the screw head 11 and the first screw removal fails, the contact position of the biting edge 22 with respect to the screw head 11 is shifted in the circumferential direction and bitten again. Therefore, the screw 10 can be removed more reliably.

  FIG. 6A and FIG. 6B show modifications of the screwdriver tool according to the first embodiment. In FIG. 6A, a guide surface 30 that is continuously curved to the tip inclined surface 25 is provided at the lower end of the cylindrical wall of the operation unit 5, and the meat guided by the tip inclined surface 25 after being shaved at the biting start end 26. The wall can be reversed and guided by the guide surface 30. The lower end of the cylindrical wall of the operation unit 5 and the starting biting end 26 are positioned on the same plane orthogonal to the central axis of the driver shaft 2. In FIG. 6B, the lower end of the cylindrical wall of the operation unit 5 is formed as a flat surface continuous to the base end of the biting edge 22, and the biting start end 26 is positioned below the lower end of the cylindrical wall of the operating unit 5. I did it. Thus, the lower end of the cylindrical wall of the operation unit 5 and the shape and structure of the tip slope 25 can be changed as necessary.

(Example 2) FIG. 7 thru | or FIG. 11 has shown the screwdriver tool which concerns on Example 2. FIG. In this case, a triangular inclined surface 32 is provided continuously at the lower ends of the pair of edge side surfaces 23, and the tip inclined surface 25 is formed by the pair of inclined surfaces 32. The lower ridge line 33 formed by the pair of inclined surfaces 32 is formed so as to be inclined upward from the inner peripheral surface 21 side toward the ridge line (upper ridge line) 24. Therefore, the side near the ridge line 24 in the lower ridge line 33 functions as the biting start end 26 of the biting edge 22. The inclination angle θ2 of the lower ridge line 33 (cutting start edge 26) was 45 degrees. Since others are the same as the previous embodiment, the same reference numerals are assigned to the same members, and descriptions thereof are omitted. The same applies to the following embodiments.

  As described above, when the tip inclined surface 25 is formed by a pair of inclined surfaces 32 and the lower ridge line 33 is provided at the intersection of both inclined surfaces 32, the wall of the screw head 11 is pressed by the pair of inclined surfaces 32. After the V-shaped leading groove 34 (see FIG. 7) is formed, the biting edge 22 can be bitten into the screw head 11 and the groove 27 can be formed. At this time, the meat wall pressed by the pair of inclined surfaces 32 and the biting edge 22 is extruded from the outer surfaces of the inclined surfaces 32 and the edge side surfaces 23 as shown in FIGS. A feeding wall 35 that protrudes toward the bottom is formed. Therefore, even if the biting depth 22 in the radial direction of the biting head 22 in the screw head 11 is the same, the engagement depth between the biting edge 22 and the screw head 11 can be increased by the amount of the biting wall 35. Therefore, the loosening force applied to the driver shaft 2 can be more suitably transmitted from the biting edge 22 to the screw head 11. In the screwdriver according to the second embodiment, the biting depth of the biting edge 22 is reduced by the amount corresponding to the leading groove 34 because the lower ridge line 33 is inclined upward toward the ridge line 24. Therefore, it is preferably used when removing the screw 10 having a large overall height of the screw head 11 such as a pan head screw, a flat head screw, a round head screw, and a binding head screw.

  In the second embodiment, the pair of inclined surfaces 32 are formed as flat surfaces, but it is not necessary. For example, the inclined surfaces 32 are formed by curved surfaces that are recessed toward the inside of the wall between the pair of inclined surfaces 32. be able to. Similarly, the edge side surface 23 can be formed by a curved surface that is recessed toward the inside of the meat wall of the biting edge 22. As described above, when the edge side surface 23 and the inclined surface 32 are formed of curved surfaces having an indented shape, the angle between the pair of edge side surfaces 23 and the pair of inclined surfaces 32 is reduced to sharpen the ridge line 24 and the lower ridge line 33. it can.

  Further, the boundary ridge line formed in the adjacent portion of the edge side surface 23 and the inclined surface 32 does not have to be positioned on the same plane orthogonal to the central axis of the driver shaft 2, and a pair of boundaries when facing the biting edge 22 The ridgeline can be formed in a wedge shape. In addition, the front-end | tip inclined surface 25 demonstrated in Example 1 can also be comprised by a pair of inclined surface 32 similarly. Or conversely, the front end slope 25 according to the second embodiment can be formed of one inclined surface in the same manner as the front end slope 25 described in the first embodiment.

  In the second embodiment, the inclination angle θ2 of the lower ridge line 33 is set to 45 degrees, but may be more than 0 degree and less than 90 degrees, but it is preferable to select within a range of 30 degrees to 60 degrees. When the inclination angle θ2 is less than 30 degrees, the meat wall of the screw head 11 is shaved downward at the biting start end 26, and the biting dimension of the biting wall 35 becomes small. Further, when the inclination angle θ2 exceeds 60 degrees, the biting depth of the biting edge 22 becomes small, and in any case, the loosening force applied to the driver shaft 2 cannot be sufficiently transmitted to the screw head 11. The operation unit 5 and the biting edge 22 in the second embodiment are configured to satisfy the inequality (D1> D2> D3).

Example 3 FIGS. 12 to 14 show a screwdriver tool according to Example 3. FIG. In this case, the front end slope 25 is omitted, and the lower end surface 38 of the biting edge 22 is formed as a flat surface so that the lower end surface 38 is flush with the lower end surface of the cylindrical wall of the operation unit 5. Further, in order to avoid the breakage of the intersection corner between the lower end surface 38 and the ridge line 24, a minute relief surface 39 is formed at the previous intersection corner, and the intersection of the minute relief surface 39 and the ridge line 24 bites into the starting edge 26. To function as. In this embodiment, the minute relief surface 39 is formed by a chamfered surface. The operation unit 5 and the biting edge 22 in Example 3 are also configured to satisfy the inequality (D1> D2> D3).

  As described above, when the lower end surface 38 of the biting edge 22 is formed as a flat surface, when the biting edge 22 bites into the screw head 11 as in the screwdriver tool of the first embodiment, the biting start end 26 and the lower end surface 38 are formed. The wall of the screw head 11 is shaved at the portion near the small relief surface 39, and the shaved wall is forced to the outside in the radial direction of the screw head 11 in the same manner as the biting edge 22 of the first embodiment. Extruded. Further, the meat wall pushed out of the screw head 11 is finally crushed by the lower end surface 38 and the lower end surface of the cylindrical wall of the operation unit 5 as shown in FIG. 12, and continues in the radial direction. It is plastically deformed. However, since the tip slope 25 is omitted, a groove 27 corresponding to the biting depth in the vertical direction of the biting edge 22 can be formed in the screw head 11, so that it is compared with the biting edge 22 of the first embodiment. The contact area between the biting edge 22 and the groove 27 can be increased. Therefore, the loosening force applied to the driver shaft 2 can be more accurately transmitted from the biting edge 22 to the screw head 11 to facilitate screw removal work.

(Example 4) FIGS. 15-17 has shown the screwdriver tool which concerns on Example 4. FIG. In this case, the tip slope 25 described in the first embodiment is provided at the lower end of the biting edge 22. As shown in FIG. 15, the inner peripheral surface 21 of the operation unit 5 is formed in an upwardly tapered shape toward the driver shaft 2, and a ridge line 24 of the biting edge 22 provided on the inner peripheral surface 21 is formed. The passing virtual cylindrical surface was formed in a tapered shape with an upward slope toward the driver shaft 2 side. Further, as shown in the developed views of FIGS. 16 and 17, the biting edge 22 and the ridge line 24 are inclined with respect to the central axis of the driver shaft 2 by an inclination angle α, and the biting start end 26 at the lower end of the ridge line 24 is The upper edge of the ridge line 24 is positioned on the upper side of the screw loosening direction.

  In the case of the screwdriver of Example 1 and Example 3, the biting depth in the radial direction with respect to the screw head 11 of the biting edge 22 is constant. However, as described above, when the virtual cylindrical surface passing through the ridge line 24 of the biting edge 22 is formed in a tapered shape that tapers upward toward the driver shaft 2, the radial direction of the biting edge 22 with respect to the screw head 11 is increased. The biting depth, that is, the depth of the groove 27 in the screw head 11 can be gradually increased. Further, since the biting start end 26 at the lower end of the ridge line 24 is positioned on the upper side of the screw loosening direction from the upper end of the ridge line 24, the biting start end 26 and the biting edge 22 are obliquely cut into the meat wall of the screw head 11. The contact area between the biting edge 22 and the groove 27 can be increased. Therefore, as a whole, the engagement strength of the biting edge 22 with the screw head 11 can be increased, and the loosening force applied to the driver shaft 2 can be accurately transmitted to the screw head 11.

(Example 5) FIGS. 18 and 19 illustrate a screwdriver tool according to Example 5. FIG. There, similarly to the screwdriver of Example 2, a triangular inclined surface 32 was provided continuously at the lower ends of the pair of edge side surfaces 23, and the tip inclined surface 25 was formed by the pair of inclined surfaces 32. Also, the lower ridge line 33 is formed by setting the inclination angle θ2 (60 degrees) of the lower ridge line 33 formed by the pair of inclined surfaces 32 to be larger than the inclination angle θ2 (45 degrees) of the lower ridge line 33 in the second embodiment. The lower edge ridge line 42 is formed continuously. As shown in FIG. 18, the lower end ridge line 42 is flush with the lower end surface of the cylindrical wall of the operation unit 5. As described above, when the inclination angle θ2 of the lower ridge line 33 is increased to form the lower edge ridge line 42 continuous with the lower end of the lower ridge line 33, the biting area of the biting edge 22 with respect to the screw head 11 can be increased.

  In each of the above-described embodiments, the case where six biting edges 22 are provided has been described, but the biting edge 22 may be provided at least at one location on the inner peripheral surface 21 of the operation unit 5. When the biting edge 22 is provided only at one location on the inner peripheral surface 21, the diameter of the inner peripheral surface 21 is D1, the diameter of the screw head 11 is D2, the ridge line 24 of the biting edge 22, and the ridge line 24 When the diameter of a virtual circle passing through the opposing inner peripheral surface 21 is D3, the biting edge 22 can be bitten into the screw head by satisfying the inequality (D1> D2> D3). However, in practice, it is preferable to provide 3 to 12 biting edges 22 on the inner peripheral surface 21 and equalize the biting depth with respect to the screw head 11 by the aligning action of each biting edge 22. The cross section of the inner peripheral surface 21 may be polygonal.

  If necessary, the structures of the plurality of pairs of biting edges 22 provided in the operation unit 5 can be made different. For example, when three pairs (six) of biting edges 22 are provided on the inner peripheral surface 21, the biting edge 22 provided with the tip slope 25 described in the first embodiment and the tip slope 25 described in the second embodiment. The biting edges 22 having the above can be alternately provided in the circumferential direction so that the respective biting edges 22 complement each other's functions. The cross-sectional shape of the biting edge 22 does not have to be triangular, and can be formed in a saw blade shape, a ratchet tooth shape, a trapezoidal shape, or the like. In this case, the angle between the radial plane passing through the ridge line 24 and each edge side surface 23 differs greatly in size, but the edge side surface 23 facing the side with the smaller pinching angle is loosened in the rotational direction. It should be positioned on the upper side. The biting edge 22 can be formed in a necessary cross-sectional shape with three or more edge side surfaces 23. For example, the biting edge 22 can be formed in a pentagonal shape with four edge side surfaces 23.

  The biting edge 22 does not need to be formed integrally with the operation unit 5, and can be configured as an independent part and attached to or removed from the operation unit 5. In that case, a plurality of biting edges 22 suitable for each screw 10 having a different screw head 11 shape are prepared, and the biting edge 22 corresponding to the head shape of the screw 10 to be removed is selected and operated. It is good to insert in the part 5 and to mount it. Similarly, the operation unit 5 can be attached to and detached from the driver shaft 2, and the plurality of operation units 5 having different structures of the biting edge 22 can be selected according to the difference in the head shape of the screw 10 or the formation material of the screw 10. The driver shaft 2 can be exchanged. The screwdriver of the present invention can be applied as a driver bit for an electric power tool in addition to being used as a manual driver. In that case, for example, after a driver bit is driven into the screw head 11 to be bitten, the driver bit is fixedly held by a chuck for an electric tool, and the screw 10 is loosened and operated.

  The driver shaft 2 need not be replaceable with respect to the grip 1 and may be integrated with the grip 1 so as not to be separated. The forming material of the driver shaft 2 may be a drawing material. The striking body 3 may be assembled to the grip 1 so as to be detachable. The screwdriver according to the present invention can also be applied when a hexagon socket head cap screw (screw) is loosened and removed. The screwdriver according to the present invention is suitable for removing screws in a state where the operation grooves of the screw heads are crushed and scraped into a mortar shape, but can also be used for tightening screws. For example, in order to prevent tampering, the operation groove may be intentionally crushed after tightening a screw to prevent loosening operation. In that case, after tightening the screw, the screw is tightened in a state where the driver is incompletely engaged with the operation groove, and the groove wall in the tightening direction of the operation groove is crushed. Similarly, although the groove wall in the loosening direction of the operation groove is crushed, the screw may be loosened at that time. In such a case, the biting edge 22 of the screwdriver according to the present invention can be bitten around the screw head 11 and the loosened screw 10 can be tightened to an appropriate state.

2 Driver shaft 5 Operation part 10 Screw 11 Screw head 13 Damaged recess 21 Inner peripheral surface 22 of the operation part 23 Cutting edge 23 Edge side face 24 Edge line 25 Tip slope 26 Cutting start edge

Claims (7)

This is a screwdriver for removing a screw whose removal target is a screw (10) in which a screw head (11) is formed in an outwardly convex curve or a part of the screw head (11) protrudes from a fastening seat. And
A cylindrical operation part (5) for loosening and operating the screw head (11) is provided at the tip of the driver shaft (2) so as to open downward.
The inner peripheral surface (21) of the operation portion (5) is provided with a biting edge (22) that bites into the peripheral edge of the surface of the screw head (11) along the central axis of the driver shaft (2),
With the lower end of the biting edge (22) in contact with the peripheral edge of the surface of the screw head (11), the driver shaft (2) is struck in the direction of its central axis, and the biting edge (22) is moved to the screw head ( 11) A screwdriver for screw removal, characterized in that the screw is cut into the peripheral edge of the surface. The biting edge (22) intersects a plurality of edge side surfaces (23) protruding toward the inner surface of the inner peripheral surface (21) of the operation portion (5) inside the inner peripheral surface (21). It is formed in a rib shape,
The diameter of the inner peripheral surface (21) of the operation portion (5) is (D1), the diameter of the screw head (11) is (D2), and the virtual circular diameter passing through the ridge line (24) of the biting edge (22) is (D3). ) On the basis of the diameter (D2) of the screw head (11),
The screwdriver for screw removal according to claim 1, wherein the inner peripheral surface (21) and the biting edge (22) satisfy the formula (D1>D2> D3).   The screw removal tool for screw removal according to claim 1 or 2, wherein three or more biting edges (22) are formed at equal intervals in the circumferential direction on the inner peripheral surface (21) of the operation portion (5). . A tip slope (25) is formed at the lower end of the biting edge (22),
The screw removal tool for screw removal according to any one of claims 1 to 3, wherein the tip inclined surface (25) is formed in a state of being inclined downward from the base end side of the biting edge (22) to the ridge line (24). . A tip slope (25) is formed at the lower end of the biting edge (22),
The tip slope (25) is formed of a pair of inclined surfaces (32) continuous to the lower ends of the pair of edge side surfaces (23),
The lower ridge line (33) formed at the intersection of the pair of inclined surfaces (32) is formed so as to incline upward from the inner peripheral surface (21) side toward the ridge line (24). The screwdriver for screw removal according to any one of 3 above.   The lower end surface (38) of the biting edge (22) is formed as a flat surface, and a minute relief surface (39) is formed at the intersection corner of the lower end surface (38) and the ridge line (24). A screwdriver for screw removal according to any one of the above. A virtual cylindrical surface passing through the ridge line (24) of the biting edge (22) provided on the inner peripheral surface (21) of the operation portion (5) is formed in a tapered shape toward the driver shaft (2). Has been
The biting edge (22) and the ridgeline (24) are inclined with respect to the center axis of the driver shaft (2), and the biting start end (26) at the lower end of the ridgeline (24) is loosened from the upper end of the ridgeline (24). The screwdriver for screw removal according to any one of claims 1 to 6, wherein the screwdriver is located on the upper side in the direction.

Images