JP6669949B2 - Pull type clamping device - Google Patents

Description

  The present invention relates to a pull-type clamping device in which a tandem-type hydraulic cylinder drives a piston rod in a retreating direction.

  In a clamping device driven by a fluid pressure cylinder, when the clamping driving force is enhanced, (a) a method of increasing the diameter of the fluid pressure cylinder, (b) a method of incorporating a booster mechanism, and (c) a series arrangement. A system employing a plurality of fluid pressure cylinders (tandem fluid pressure cylinders) has been put to practical use.

  Regarding the clamp device or the fluid pressure cylinder adopting the method (c), the techniques described in Patent Literature 1 and Patent Literature 2 are known.

  The fluid pressure cylinder disclosed in Patent Document 1 has three double-acting fluid pressure cylinders arranged in series on a common cylinder body. In this fluid pressure cylinder, three independent cylinder holes are formed in series in a cylinder body, piston members are movably mounted in the three cylinder holes, respectively, and a common piston fixed through these piston members is fixed. The rod extends from one end of the cylinder body to the outside of the cylinder body, and a fluid pressure working chamber is formed on each side of the piston member in each cylinder hole. In each of the three cylinder holes, two fluid pressure ports capable of supplying / discharging fluid pressure from outside to two fluid pressure working chambers are formed in the cylinder body.

  In the fluid pressure cylinder disclosed in Patent Document 2, an outer piston is movably mounted in a large-diameter cylinder hole formed in a cylinder body, an outer rod extending from the outer piston toward the distal end is fixed to the outer piston, and a small-diameter cylinder hole is formed in the outer rod. The end of the small-diameter cylinder hole is closed by a rod cover, the inner piston is mounted in the small-diameter cylinder hole so as to be relatively movable, and the inner piston extends from the head-side end wall of the cylinder body and penetrates the outer piston. The piston is fixed, the first and second fluid pressure working chambers are formed on both sides of the outer piston, the third fluid pressure working chamber is formed on the tip side of the inner piston, and the inner tube is inserted into the shaft hole inside the inner rod. It is installed.

  A first fluid pressure passage communicating from the first fluid pressure port formed in the cylinder body to the first fluid pressure working chamber, and a second fluid pressure passage formed in the cylinder body through the second fluid passage outside the inner tube in the inner rod. A second fluid pressure passage leading to the fluid pressure working chamber and a third fluid pressure passage leading from the first fluid pressure port through the inner tube to the third fluid pressure working chamber are formed.

JP-A-6-323306 JP-A-8-200315

  The fluid pressure cylinder disclosed in Patent Document 1 has a configuration in which a total of six fluid pressure ports are formed in a cylinder body, and fluid pressure is supplied / discharged to the six fluid pressure ports by piping or hoses outside the fluid pressure cylinder. Therefore, there is a problem that the fluid pressure supply system becomes complicated, the production cost becomes high, and the fluid pressure cylinder becomes large.

  In the fluid pressure cylinder of Patent Document 2, it is possible to drive the outer rod (output rod) in the extending direction by the fluid pressure supplied to the first and third fluid pressure working chambers. Since the outer rod is driven in the retracting direction by pressure, the driving force in the extending direction can be enhanced, but the driving force in the retracting direction cannot be enhanced. Therefore, even if the fluid pressure cylinder of Patent Literature 2 is applied to a pull-type clamp device of a type in which the output rod is driven to clamp in the retreating direction, the clamp driving force cannot be enhanced. In addition, in the fluid pressure cylinder disclosed in Patent Document 2, the fluid pressure supply system is complicated, and the production cost is high.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pull-type clamp device in which a fluid pressure passage for supplying / discharging fluid pressure to / from a first and second fluid pressure working chambers is formed in a wall of a cylinder body.

The pull-type clamping device according to claim 1, wherein the tandem-type hydraulic pressure cylinder drives the piston rod in a retracting direction by a tandem-type hydraulic pressure cylinder. First and second cylinder holes formed in series so as to line up in the retreating direction therein, and first and second piston portions movably mounted in the first and second cylinder holes, respectively. A common piston rod fixed to the first and second piston portions and extending from the first piston portion side to outside the cylinder body, wherein the cylinder body has a cylinder hole forming wall portion, and a cylinder hole forming wall portion. A rod-side end wall integral with the portion, and a partition wall for partitioning between the first and second cylinder holes and through which the piston rod penetrates. The first and second clamping fluid pressure working chambers are formed on the rod side end wall side with respect to the second piston portion, respectively. A fluid pressure passage for clamping capable of supplying fluid pressure to the fluid pressure working chamber for clamping is formed, and a first fluid pressure for unclamping is provided on a partition wall side of the first cylinder hole with respect to the first piston portion. working chamber is formed, the fluid pressure passages for unclamping capable of supplying fluid pressure is formed in the fluid pressure operation chamber for first unclamping in the wall portion of the cylinder body, the cylinder body of the second cylinder bore A second unclamping fluid pressure working chamber is formed on the head side end wall side of the second cylinder hole with respect to the second piston portion, wherein the second cylinder hole has a head side end wall for closing the end portion; First and second anchors in rod Pump the fluid pressure operation chamber rod fluid pressure passage which communicates with a formed, as characterized in that the inner diameter of the second cylinder hole is larger than the outer diameter of the inner diameter and the partition wall of the first cylinder bore I have.

The pull-type clamping device according to claim 2 is characterized in that, in the invention according to claim 1 , a piston rod turning mechanism having a plurality of steel balls and a plurality of spiral grooves with which the plurality of steel balls are engaged is provided. I have.

According to a third aspect of the present invention, in the second aspect , the plurality of steel balls are mounted on an inner peripheral wall of a piston rod through hole of the partition wall, and the plurality of spiral grooves are formed on an outer periphery of the piston rod. It is characterized in that it is formed in the part.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a fluid pressure short-circuiting passage is formed in the partition wall, the fluid pressure short-circuiting passage communicating the clamping fluid pressure passage with the first unclamping fluid pressure working chamber. The fluid pressure short-circuiting passage is provided with an on-off valve mechanism that opens only when the first piston moves to a full stroke toward the clamp side.

The present invention has the following effects because it has the configuration described in the section of the means for solving problems.
According to the first aspect of the present invention, a clamping fluid passage that can supply fluid pressure from one common fluid pressure port to the first and second clamping fluid pressure working chambers is formed in the wall of the cylinder body. Therefore, the fluid pressure supply system for supplying fluid pressure to the first and second clamping fluid pressure working chambers can be simplified, the clamp device can be downsized, and the manufacturing cost can be reduced.
Since the piston rod can be driven in the retreating direction by the fluid pressure in the first and second clamping fluid pressure working chambers, the driving force of the pull-type clamp device can be enhanced.
Then, fluid pressure is supplied to the first unclamping fluid pressure working chamber to form an unclamping fluid pressure passage capable of supplying fluid pressure to the first unclamping fluid pressure working chamber within the wall of the cylinder body. The fluid pressure supply system can be simplified, the clamp device can be downsized, and the manufacturing cost can be reduced.
In addition, since the second unclamping fluid pressure working chamber is formed in addition to the first unclamping fluid pressure working chamber, the driving force for unclamping the piston rod in the extension direction can be enhanced.
Also, a fluid pressure supply system for supplying fluid pressure to the second unclamping fluid pressure working chamber to form a rod fluid pressure passage communicating with the first and second unclamping fluid pressure working chambers in the piston rod. Is simplified and compact.

Since it is not necessary to form a fluid pressure passage in the wall of the cylinder body on the outer peripheral side of the second cylinder hole, the diameter of the second cylinder hole is made larger than that of the first cylinder hole, and The pressure receiving area can be increased to enhance the clamp driving force.

According to the invention of claim 2 , when the piston rod is extended and retracted, the piston rod can be rotated by the piston rod turning mechanism.

According to the invention of claim 3, comprising a pivotable piston rod relative to the partition wall via a plurality of steel balls and a plurality of spiral grooves.

According to the fourth aspect of the present invention, the opening / closing valve mechanism opens only when the first piston moves to the clamp side by a full stroke, and the clamping fluid pressure passage communicates with the first unclamping fluid pressure working chamber. Therefore, the fluid pressure in the clamping fluid pressure passage does not rise. Therefore, it can be detected from the fluid pressure in the clamping fluid pressure passage that the clamp state is not normal (clamp failure).

It is a longitudinal section of a pull type clamp device (unclamped state) of Example 1 of the present invention. FIG. 2 is a plan view of the pull-type clamp device (unclamped state) of FIG. 1. It is a longitudinal cross-sectional view of the pull-type clamp device (clamp state) of FIG. FIG. 10 is a longitudinal sectional view of a pull-type clamp device (an unclamped state) according to a second embodiment. FIG. 5 is a longitudinal sectional view of the pull-type clamp device (clamp state) of FIG. 4. FIG. 10 is a longitudinal sectional view of a pull-type clamp device (an unclamped state) according to a third embodiment. FIG. 7 is a longitudinal sectional view of the pull-type clamp device (clamp state) of FIG. 6. FIG. 13 is a longitudinal sectional view of a pull-type clamp device (clamp state) according to a fourth embodiment. It is an enlarged view of the A section of FIG. FIG. 9 is a vertical sectional view of the pull-type clamp device (clamp failure state) of FIG. 8. It is an enlarged view of the B section of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described based on examples.

As shown in FIGS. 1 to 3, a pull-type clamping device 1 of the present application is a clamping device in which a piston rod 6 is clamp-driven in a retreating direction by a tandem-type hydraulic cylinder 2 having a vertical axis. .
The tandem type hydraulic cylinder 2 includes a cylinder body 3 having a vertical axis, first and second cylinder holes 4a and 4b formed in series in the cylinder body 3, and first and second cylinder holes 3a and 4b. The first and second piston portions 5a and 5b movably mounted in the cylinder holes 4a and 4b, respectively, and the first and second piston portions 5a and 5b are fixed to the first and second piston portions 5a and 5b, respectively. And a common piston rod 6 that extends to In this embodiment, “fluid pressure” means a pressurized fluid. Although "hydraulic pressure (pressurized oil)" is used as "fluid pressure", pressurized air may be used.

The cylinder body 3 partitions between a cylinder hole forming wall 3a, a rod-side end wall 3b integral with the cylinder hole forming wall 3a, and first and second cylinder holes 4a and 4b, and a piston rod 6 is formed. A partition wall 7 penetrating therethrough and a head-side end wall 3d for closing an end of the second cylinder hole 4b are provided.
The inside diameter of the second cylinder hole 4b is formed larger than the inside diameter of the first cylinder hole 4a and the outside diameter of the partition wall 7.

  A rectangular mounting wall 3c (including a rod-side end wall 3b) having a predetermined thickness is formed on an upper portion of the cylinder body 3, and a horizontal mounting surface 8 is formed on a lower end of the mounting wall 3c. Is formed, and the upper end portion of the cylinder hole forming wall portion 3a is constituted by a part of the mounting wall portion 3c. The cylinder hole forming wall portion 3a is inserted into the through hole 9a of the base member 9 to which the clamp device 1 is attached, and the mounting surface is The cylinder body 3 is fixed to the base member 9 with four bolts inserted into the four bolt holes 10 in a state in which the cylinder body 8 is in contact with the upper surface of the base member 9.

  Of the first and second cylinder holes 4a and 4b, the first and second clamping fluid pressure working chambers 11a and 11b are respectively located on the rod side end wall 3b side with respect to the first and second piston parts 5a and 5b. The first and second unclamping fluid pressure actuation is formed on the side of the first and second cylinder holes 4a and 4b opposite to the rod side end wall 3b with respect to the first and second piston parts 5a and 5b. Chambers 12a and 12b are respectively formed.

  The partition wall 7 has a large-diameter portion 7a of approximately 2/3 on the upper side and a small-diameter portion 7b of approximately 1/3 of the lower side, and a lower end of the outer peripheral portion of the large-diameter portion 7a is formed by a cylinder hole forming wall portion 3a. The partition wall 7 is restricted so as not to move downward by being received by the stop ring 13 attached to the inner surface of the partition wall 7. The outer diameter of the lower half part of the large diameter part 7a is formed slightly larger than the outer diameter of the upper half part of the large diameter part 7a, and the partition wall 7 is regulated so as not to move upward.

The piston rod 6 has a vertical axis and is integrally formed with the first piston portion 5a, and the upper half of the piston rod 6 is inserted into the rod hole 14 of the rod-side end wall 3b to move above the cylinder body 3. Extending. A base end of a clamp arm 15 in a horizontal posture is fixed to an upper end of the piston rod 6. That is, the upper end of the piston rod 6 is formed with a tapered portion 6a whose diameter becomes smaller toward the upper side, and the base end of the clamp arm 15 is externally fitted to the tapered portion 6a and screwed from the upper end of the piston rod 6. The base end of the clamp arm 15 is fastened and fixed to the clamp rod 6 by a vertical fixing bolt 16 via a washer 16a. A seal member 17 and a dust seal 18 are mounted on the inner peripheral portion of the rod hole 14 of the rod side end wall 3b.

  The lower half of the piston rod 6 extends through the rod hole 19 (piston rod through hole) of the partition wall 7 into the second cylinder hole 4b. The second piston portion 5b is inserted into the rod hole 20 of the portion 5b, and is connected to the piston rod 6 by a stop ring 21 attached to the lower end portion of the piston rod 6 so as to move up and down integrally with the piston rod 6.

  A seal member 22 is attached to an outer peripheral portion of the first piston portion 5a, a seal member 23 is attached to an outer peripheral portion of the second piston portion 5b, and a seal member is attached to an inner peripheral portion of the rod hole 20 of the second piston portion 5b. A member 24 is mounted. A seal member 25 is attached to an outer peripheral portion near an upper end of the partition wall 7, and a seal member 26 is attached to an inner peripheral portion near an upper end of the rod hole 19 of the partition wall 7. The head side end wall 3d is prevented from coming off by a stop ring 27 mounted on the cylinder hole forming wall 3a, and a seal member 28 is mounted on the outer peripheral portion of the head side end wall 3d.

In the wall of the cylinder body 3, a clamping fluid passage 32 capable of supplying fluid pressure from one common first fluid pressure port 31 to the first and second clamping fluid pressure working chambers 11a and 11b is formed. ing. Second fluid pressure port 33 from the first unclamping fluid pressure operation chamber 12a unclamping fluid pressure passage 34 capable of supplying fluid pressure is formed in the wall of the cylinder body 3, first in the piston rod 6, An in-rod fluid pressure passage 35 communicating the second unclamping fluid pressure working chambers 12a and 12b is formed. The upper end of the in-rod fluid pressure passage 35 communicates with the first unclamping fluid pressure working chamber 12a near the lower end of the first piston portion 5a.

  The first hydraulic pressure port 31 is formed so as to face the installation surface 8 of the installation wall 3c, the first hydraulic pressure passage 9b in the base member 9 is connected to the first hydraulic pressure port 31, and the first hydraulic pressure passage 31 is provided. 9b is connected to a fluid pressure supply source (not shown). The second hydraulic pressure port 33 is formed so as to face the installation surface 8 of the installation wall 3c, a second hydraulic pressure passage (not shown) in the base member 9 is connected to the second hydraulic pressure port 33, and The fluid pressure passage is connected to a fluid pressure supply source (not shown).

  The clamping fluid pressure passage 32 is formed in the fluid pressure passage 32a formed in the installation wall 3c and the cylinder hole forming wall 3a of the cylinder body 3, and in the partition wall 7 so as to communicate with the fluid pressure passage 32a. And a fluid pressure passage 32b. An annular groove 36 is formed in the inner peripheral portion of the partition wall mounting hole 4c where the partition wall 7 is mounted and the outer peripheral portion of the partition wall 7 so as to communicate with the lower end portion of the fluid pressure passage 32b. The fluid pressure passage 32b in the partition wall 7 extends horizontally from the annular groove 36 and then extends downward, and communicates with the second clamping fluid pressure working chamber 11b.

  The unclamping fluid pressure passage 34 extends from the second fluid pressure port 33, passes through the inside of the installation wall 3c, the rod side end wall 3b, and the cylinder hole forming wall 3a, and passes through the first unclamping fluid pressure working chamber. It communicates with an annular groove 37 at the lower end of 12a.

  When the piston rod 6 is turned 90 ° counterclockwise in plan view when the piston rod 6 retreats from the unclamped state to the clamped state, and when the piston rod 6 is extended from the clamped state to the unclamped state. A piston rod turning mechanism 40 for turning the piston rod 6 90 ° clockwise in plan view is provided.

The piston rod turning mechanism 40 includes a plurality of (for example, three) steel balls 41 attached to the inner peripheral wall of the rod hole 19 of the partition wall 7, and the piston rod 6 of the piston rod 6 is engaged with the steel balls 41. It has a plurality (for example, three) of engagement grooves 42 formed on the outer peripheral portion.
Each engagement groove 42 is formed by a spiral groove 42a corresponding to an opening angle of 90 ° with respect to the center of the piston rod 6, and a linear groove extending linearly upward from the upper end of the spiral groove 42a.

Next, the operation and effects of the pull-type clamp device 1 described above will be described.
When switching from the unclamped state in FIG. 1 to the clamped state in FIG. 3, fluid pressure is supplied from the first fluid pressure port 31 to the first and second clamping fluid pressure working chambers 11a and 11b, and the first and second unclamped states. When the fluid pressure is discharged from the clamping fluid pressure working chambers 12a and 12b, the first and second piston parts 5a and 5b receive pressure and the piston rod 6 is driven to clamp in the retreating direction to be in the clamping state shown in FIG.

  In the unclamped state, the clamp arm 15 faces rearward in FIG. 1, but when switching from the unclamped state to the clamped state, the piston rod 6 is moved by the piston rod turning mechanism 40 in the first half of the downward movement of the piston rod 6. The piston rod 6 turns in a counterclockwise direction by 90 °, and in the latter half of the downward movement, the piston rod 6 moves downward without rotating and clamps the object to be clamped.

  When switching from the clamped state to the unclamped state, contrary to the above, fluid pressure is supplied to the first and second unclamping fluid pressure working chambers 12a and 12b, and the first and second clamping fluid pressure working chambers are supplied. The fluid pressure is discharged from 11a and 11b. At this time, in the first half of the upward movement of the piston rod 6, the piston rod 6 rises without rotating, and in the second half of the upward movement, the piston rod 6 rotates clockwise by 90 °.

A clamping fluid passage 32 capable of supplying fluid pressure from one common first fluid pressure port 31 to the first and second clamping fluid pressure working chambers 11a and 11b is formed in the wall of the cylinder body 3. The fluid pressure supply system for supplying fluid pressure to the first and second clamping fluid pressure working chambers 11a and 11b can be simplified, the clamp device 1 can be downsized, and the manufacturing cost can be reduced. Since the piston rod 6 can be clamp-driven in the retreating direction by the fluid pressure of the first and second clamping fluid pressure working chambers 11a and 11b, the driving force of the pull-type clamp device 1 can be enhanced.

Since it is not necessary to form a fluid pressure passage in the wall of the cylinder body 3 on the outer peripheral side of the second cylinder hole 4b , the inner diameter of the second cylinder hole 4b is set outside the inner diameter of the first cylinder hole 4a and outside the partition wall 7. The diameter is formed larger than the diameter, and the pressure receiving area of the second piston portion 5b can be increased to enhance the clamp driving force. When the piston rod 6 is extended / retracted, the piston rod 6 can be pivoted by the piston rod pivoting mechanism 40.

  In order to form an unclamping fluid pressure passage 34 capable of supplying fluid pressure to the first unclamping fluid pressure working chamber 12a in the wall of the cylinder body 3, a fluid pressure is applied to the first unclamping fluid pressure working chamber 12a. The fluid pressure supply system to be supplied can be simplified, the clamp device 1 can be downsized, and the manufacturing cost can be reduced.

  Since the second hydraulic fluid operating chamber for unclamping 12b is formed in addition to the first hydraulic fluid operating chamber for unclamping 12a, the driving force for unclamping the piston rod 6 in the extending direction can be enhanced. Fluid pressure is supplied to the second unclamping fluid pressure operating chamber 12b in order to form the rod internal fluid pressure passage 35 communicating the first and second unclamping fluid pressure working chambers 12a and 12b in the piston rod 6. The fluid pressure supply system is simplified and compact.

Second Embodiment A pull-type clamp device 1A according to a second embodiment will be described with reference to FIGS.
Since this pull-type clamp device 1A is obtained by simply omitting some components of the pull-type clamp device 1, the same components as those of the pull-type clamp device 1 are denoted by the same reference numerals, and description thereof is omitted. Only different configurations will be described.

  In the tandem-type hydraulic cylinder 2A of the pull-type clamp device 1A, since it is not necessary to enhance the unclamping driving force, the head-side end wall 3d, the stop ring 27, and the second unclamping hydraulic pressure working chamber 12b is omitted. Therefore, the structure of the pull-type clamp device 1A is somewhat simplified.

Third Embodiment A pull-type clamp device 1B according to a third embodiment will be described with reference to FIGS.
Since the pull-type clamp device 1B is obtained by merely changing a part of the configuration of the pull-type clamp device 1, the same reference numerals are given to the same components as those of the pull-type clamp device 1, and description thereof will be omitted. Only different configurations will be described.

  In the tandem-type hydraulic cylinder 2B of the pull-type clamp device 1B, the partition wall 7B has a large-diameter portion 7a, a lower-end-side small-diameter portion 7b extending downward from a lower end of the large-diameter portion 7a, and a large-diameter portion 7a. And an upper end side small diameter portion 7c extending upward from the upper end. The turning mechanism 40 is formed on the upper end side small diameter portion 7 c and the piston rod 6.

A cylindrical portion 29 extending from the second piston portion 5b toward the partition wall 7B by a predetermined length and slidably inserted into the large-diameter portion 7a and the lower-end small-diameter portion 7b of the partition wall 7B in a fluid-tight manner; A cylindrical portion 29 externally fitted and fixed to the second piston portion 5b is integrally formed. The lower part of the piston rod 6 is inserted through a rod hole 29a formed in the cylindrical portion 29, and the cylindrical portion 29 is slidably inserted into an insertion hole 7h formed in the partition wall 7B .

  On the outer peripheral side of the piston rod 6, a rod-external fluid pressure passage 30 communicating the first and second unclamping fluid pressure working chambers 12a and 12b is formed. The rod outer fluid pressure passage 30 includes a lower end portion of the engagement groove 42 and a linear groove 30 a linearly formed in the inner peripheral portion of the rod hole 29 a of the cylindrical portion 29. The upper end portion of the straight groove 30a is formed wide in the circumferential direction so as to always communicate with the lower end portion of any of the engagement grooves 42 even when the piston rod 6 turns. In addition, a seal member 38 is mounted on the inner peripheral portion of the insertion hole 7h near the lower end of the insertion hole 7h.

  In the pull-type clamp device 1B, since there is no seal member between the piston rod 6 and the partition wall 7B, the frictional resistance acting on the piston rod 6 when the piston rod 6 turns is reduced, thereby improving the turning performance. be able to.

Fourth Embodiment A pull-type clamp device 1C according to a fourth embodiment will be described with reference to FIGS.
Since the pull-type clamp device 1C is obtained by changing only a part of the configuration of the pull-type clamp device 1, the same components as those of the pull-type clamp device 1 are denoted by the same reference numerals, and description thereof is omitted. Only different configurations will be described.

The tandem-type hydraulic cylinder 2C of the pull-type clamp device 1C is provided with a defective-clamp detecting means 50 including a hydraulic short-circuit path 51, an opening / closing valve mechanism 52, a pressure sensor 53, and a control unit 57 as described below. .
A fluid pressure short circuit passage 51 is formed in the partition wall 7 </ b> C to connect the clamping fluid pressure passage 32 and the annular groove 36 to the first unclamping fluid pressure operating chamber 12 a. An on-off valve mechanism 52 that opens only when the portion 5a has moved to the clamp side by a full stroke is provided.

  The opening / closing valve mechanism 52 has a vertical axis, and includes a valve body housing hole 54, a valve body 55, and a compression spring 56. The valve body accommodating hole 54 has a large diameter hole 54a and a small diameter hole 54b extending from the upper end of the large diameter hole 54a to the first unclamping fluid pressure working chamber 12a.

  The valve element 55 has a large diameter portion 55a and a medium diameter portion 55b housed in the large diameter hole 54a, and a small diameter extending from the upper end of the medium diameter portion 55b into the small diameter hole 54b and facing the first piston portion 5a. A small-diameter portion 55c whose upper end protrudes into the first unclamping fluid pressure working chamber 12a. A compression spring 56 for urging the valve body 55 upward is mounted below the large diameter hole 54a.

  When the outer peripheral portion of the upper end of the middle diameter portion 55b contacts the lower end of the outer peripheral side wall portion of the small diameter hole 54b, the valve is closed (see FIG. 9). Since the one piston portion 5a pushes the valve body 55 downward, the valve is opened (see FIG. 11).

  A pressure sensor 53 (or pressure switch) capable of detecting the fluid pressure in the first fluid pressure passage 9b in the base member 9 is provided, and a detection signal of the pressure sensor 53 is output to the control unit 57.

  When the clamping object is normally clamped when the clamping device 1C is driven for clamping, the first piston portion 5a does not move to the clamp side by a full stroke, and therefore, as shown in FIGS. The piston portion 5a does not push the valve body 55, and the opening / closing valve mechanism 52 maintains the valve closed state. Therefore, the fluid pressure in the first fluid pressure passage 9b does not drop abnormally, and the control unit 57 can detect the normal clamping from the detection signal of the pressure sensor 53.

  On the other hand, when the clamp object is not present or the thickness of the clamp object is too small, when the clamping device 1C is driven to clamp, the first piston portion 5a moves full-stoke to the clamp side. As shown in FIGS. 10 and 11, the opening / closing valve mechanism 52 is opened, and the fluid pressure in the first fluid pressure passage 9b drops abnormally. Therefore, the control unit 57 can detect the occurrence of the clamping failure from the detection signal of the pressure sensor 53.

Next, an example in which the above embodiment is partially changed will be described.
1) The clamping failure detecting means 50 of the fourth embodiment can be applied to the pull-type clamping devices 1A and 1B of the second and third embodiments.

  2) The first and second fluid pressure ports 31 and 33 do not need to be formed so as to face the installation surface 8 of the installation wall 3c, and may be formed so as to face the side surface of the installation wall 3c.

3) The tandem hydraulic Cylinders in the Examples, the first two, second cylinder hole and the first has been described as an example having a second piston part, three or more in series to form A tandem-type hydraulic cylinder having a cylinder hole and three or more piston portions is also applicable to the pull-type clamp device of the present application.

  4) In addition, those skilled in the art can carry out the present invention in a form in which various modifications are added to the above-described embodiment, and the present invention includes such modifications.

1, 1A-1C Pull type clamping device 2, 2A-2C Tandem type hydraulic cylinder 3 Cylinder body 3a Cylinder hole forming wall portion 3b Rod side end wall 3d Head side end wall 4a, 4b First, second cylinder hole 5a, 5b First and second piston portions 6 Piston rods 7, 7B, 7C Partition walls 11a, 11b First and second clamping fluid pressure working chambers 12a, 12b First and second unclamping fluid pressure working chambers 19 Rod penetration Hole (rod hole)
29 cylindrical portion 30 rod outside fluid pressure passage 31 first fluid pressure port 32 clamping fluid pressure passage 34 unclamping fluid pressure passage 35 rod internal fluid pressure passage 40 turning mechanism 41 steel ball 42a spiral groove 51 fluid pressure short circuit passage 52 opening and closing Valve mechanism

Claims (4)

In a pull-type clamping device configured to clamp-drive a piston rod in a retreating direction by a tandem-type fluid pressure cylinder,
The tandem type hydraulic cylinder includes a cylinder body, first and second cylinder holes formed in series in the cylinder body so as to be aligned in the retreating direction, and the first and second cylinder holes. And a common piston rod fixed to the first and second piston portions and extending from the first piston portion side to outside of the cylinder body, respectively.
The cylinder body includes a cylinder hole forming wall portion, a rod-side end wall integrated with the cylinder hole forming wall portion, and a partition wall that partitions between the first and second cylinder holes and through which a piston rod passes.
Of the first and second cylinder holes, the first and second clamping fluid pressure working chambers are respectively formed on the rod side end wall side with respect to the first and second piston portions,
A fluid passage for clamping capable of supplying fluid pressure from one common fluid pressure port to the first and second fluid working chambers for clamping is formed in a wall portion of the cylinder body,
In the first cylinder hole, a first unclamping fluid pressure working chamber is formed on the partition wall side with respect to the first piston portion, and the first unclamping fluid pressure working chamber is formed in the cylinder body wall portion. fluid pressure passage for unclamping capable of supplying fluid pressure is formed,
The cylinder body has a head-side end wall that closes an end of the second cylinder hole,
A second unclamping fluid pressure working chamber is formed on the head side end wall side of the second cylinder hole with respect to the second piston portion,
A rod-in fluid pressure passage communicating with the first and second unclamping fluid pressure working chambers is formed in the piston rod,
A pull-type clamp device, wherein an inner diameter of the second cylinder hole is formed larger than an inner diameter of the first cylinder hole and an outer diameter of the partition wall . 2. The pull-type clamp device according to claim 1 , further comprising a piston rod turning mechanism having a plurality of steel balls and a plurality of spiral grooves respectively engaged with the plurality of steel balls . The plurality of steel balls are mounted on the inner peripheral wall of the piston rod through hole of the partition wall,
The pull-type clamp device according to claim 2 , wherein the plurality of spiral grooves are formed on an outer peripheral portion of the piston rod . A fluid pressure short-circuiting passage is formed in the partition wall to communicate the clamping fluid pressure passage with a first unclamping fluid pressure working chamber,
2. The pull-type clamp device according to claim 1, wherein an opening / closing valve mechanism that opens only when the first piston moves to a full stroke toward the clamp side is provided in the fluid pressure short-circuit passage .