JP6867340B2 - Gripping device - Google Patents

Description

The present invention relates to a gripping device.

As shown in FIG. 7, for example, the gripping device 100 of Patent Document 1 is housed in a cylindrical body 102 having a cylinder chamber 101 to which a fluid is supplied and discharged, and a cylinder chamber 101, and is supplied and discharged to the cylinder chamber 101. It includes a piston 103 that reciprocates with a fluid, and a pair of master jaws 104 that open and close with the reciprocating movement of the piston 103.

Further, in Patent Document 1, an LVDT sensor 105 (differential transformer) is used to detect the positions of the pair of master jaws 104. The LVDT sensor 105 reciprocates integrally with the tubular sensor case main body 106, the primary coil 107 wound around the sensor case main body 106, the two secondary coils 108, and the piston 103, and is attached to the sensor case main body 106. On the other hand, it has a core shaft 109 that can appear and disappear. An AC voltage is applied to the primary coil 107. Then, the core shaft 109 reciprocates with the reciprocating movement of the piston 103, so that a difference occurs in the induced voltage generated in each of the secondary coils 108. This difference in induced voltage changes depending on the position of the core shaft 109. Further, the moving amount of the pair of master jaws 104 and the moving amount of the piston 103 are in a proportional relationship. Therefore, the amount of movement of the core shaft 109, that is, the amount of movement of the piston 103 can be detected by the amount of change in the difference in induced voltage, and as a result, the amount of movement of the pair of master jaws 104 can be detected. According to this, the positions of the pair of master jaws 104 can be detected linearly, and the positions of the pair of master jaws 104 can be detected with high accuracy.

Japanese Unexamined Patent Publication No. 11-320474

By the way, in the gripping device 100 of Patent Document 1, the first head cover 111 and the second head cover 112 are attached to the end portion in the axial direction of the body 102. The first head cover 111 is formed with a through hole 111a through which the sensor case main body 106 penetrates. The sensor case main body 106 is fixed to the first head cover 111 and the second head cover 112 by being sandwiched between the first head cover 111 and the second head cover 112 in a state where the sensor case main body 106 penetrates the through hole 111a of the first head cover 111. ing. Then, by attaching the first head cover 111 and the second head cover 112 to the end portion of the body 102, the sensor case main body 106 is located in the body 102 in a state of being arranged coaxially with the piston 103.

At this time, the sensor case main body 106 is located in the body 102 in a state of being cantilevered by the first head cover 111 and the second head cover 112. Therefore, depending on the mounting state of the first head cover 111 and the second head cover 112 with respect to the body 102, the sensor case main body 106 may be arranged in the body 102 in a state of being tilted with respect to the axis of the core shaft 109. .. Then, there is a possibility that the sensor case main body 106 on the core shaft 109 is difficult to move in and out, and the positions of the pair of master jaws 104 cannot be detected accurately.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a gripping device capable of smoothing the movement of the core shaft with respect to the sensor case main body.

The gripping device for solving the above problems includes a tubular body having a cylinder chamber to which fluid is supplied and discharged, a piston housed in the cylinder chamber and reciprocating by the fluid supplied and discharged to the cylinder chamber, and the above. A head cover attached to an axial end of the body, a pair of master jaws that open and close with the reciprocating movement of the piston, and a pair of master jaws that are built into the body while being arranged coaxially with the piston. The LVDT sensor includes a tubular sensor case body, a primary coil wound around the sensor case body, two secondary coils, and the piston. A gripping device having a core shaft that reciprocates integrally and can appear and disappear with respect to the sensor case main body, and is in contact with the sensor case main body around the axis of the sensor case main body. It is provided with an urging member that contacts and urges the sensor case body toward the head cover and cooperates with the head cover to sandwich the sensor case body.

In the gripping device, the outer peripheral surface of the sensor case body is an annular seal that seals between the outer peripheral surface of the sensor case body and the inner peripheral surface of the body to prevent fluid from leaking from the cylinder chamber. It is preferable that a member is provided.

In the gripping device, the head cover may have a male screw portion screwed into the body, and may further include a rotation stop mechanism for preventing rotation of the sensor case body with respect to the body.

According to the present invention, the movement of the core shaft with respect to the sensor case body can be made smooth.

FIG. 3 is a cross-sectional view of the gripping device according to the embodiment. FIG. 5 is an enlarged cross-sectional view showing the gripping device. The cross-sectional view of the gripping device which shows the state which gripped the work. Top view of the body. An exploded sectional view of the gripping device. FIG. 5 is an enlarged sectional view showing a gripping device according to another embodiment. FIG. 3 is a cross-sectional view of a gripping device in a conventional example.

Hereinafter, an embodiment in which the gripping device is embodied will be described with reference to FIGS. 1 to 5.
As shown in FIG. 1, the gripping device 10 includes a square tubular body 11. The body 11 is formed with a circular through hole 12 that penetrates in the axial direction of the body 11. The through hole 12 is formed by a female screw hole 13, a sensor accommodating hole 14, a cylinder hole 15, a rod insertion hole 16, and an accommodating hole 17. The female screw hole 13, the sensor accommodating hole 14, the cylinder hole 15, the rod insertion hole 16, and the accommodating hole 17 are formed in the body 11 in this order from one end to the other end in the axial direction of the body 11. Therefore, the female screw hole 13 is open to one end surface 11a of the body 11. The accommodating hole 17 is open to the other end surface 11b of the body 11.

The end of the female screw hole 13 on the side opposite to the one end surface 11a of the body 11 communicates with the sensor accommodating hole 14. The end of the sensor accommodating hole 14 opposite to the female screw hole 13 communicates with the cylinder hole 15. The end of the cylinder hole 15 opposite to the sensor accommodating hole 14 communicates with the rod insertion hole 16. The end of the rod insertion hole 16 opposite to the cylinder hole 15 communicates with the accommodating hole 17.

The hole diameter of the female screw hole 13 is larger than the hole diameter of the sensor accommodating hole 14. Further, the hole diameter of the sensor accommodating hole 14 is larger than the hole diameter of the cylinder hole 15. Therefore, the body 11 has an annular first stepped surface 18 that connects the inner peripheral surface of the sensor accommodating hole 14 and the inner peripheral surface of the cylinder hole 15 and extends in a direction orthogonal to the axial direction of the body 11. ing. Further, the hole diameter of the cylinder hole 15 is larger than the hole diameter of the rod insertion hole 16. Therefore, the body 11 has an annular second stepped surface 19 that connects the inner peripheral surface of the cylinder hole 15 and the inner peripheral surface of the rod insertion hole 16 and extends in a direction orthogonal to the axial direction of the body 11. ing.

The hole diameter of the rod insertion hole 16 is smaller than the hole diameter of the accommodating hole 17. Therefore, the body 11 has an annular third stepped surface 20 that connects the inner peripheral surface of the rod insertion hole 16 and the inner peripheral surface of the accommodating hole 17 and extends in a direction orthogonal to the axial direction of the body 11. ing. An annular seal mounting groove 16a is formed on the inner peripheral surface of the rod insertion hole 16. The seal mounting groove 16a is open to the third stepped surface 20.

As shown in FIG. 2, the sensor accommodating hole 14 is formed of a small-diameter hole 14a and a large-diameter hole 14b having a larger hole diameter than the small-diameter hole 14a. The small diameter hole 14a is located closer to the cylinder hole 15 than the large diameter hole 14b and communicates with the cylinder hole 15. The large diameter hole 14b communicates with the female screw hole 13. The inner peripheral surface of the small diameter hole 14a and the inner peripheral surface of the large diameter hole 14b are connected by a conical tapered surface 14c. The tapered surface 14c is reduced in diameter from the large diameter hole 14b toward the small diameter hole 14a.

As shown in FIG. 1, a pair of flat plate-shaped support portions 21 project from the other end surface 11b of the body 11. In FIG. 1, for convenience of drawing, only one of the pair of support portions 21 is shown. The pair of support portions 21 project from the other end surface 11b of the body 11 in the axial direction of the body 11. The pair of support portions 21 extend parallel to each other. The through hole 12 is open between the pair of support portions 21.

A disc-shaped spring receiving member 22 is housed in the through hole 12. The outer diameter of the spring receiving member 22 is larger than the hole diameter of the cylinder hole 15 and slightly smaller than the hole diameter of the small diameter hole 14a of the sensor accommodating hole 14. The outer peripheral portion of the one end surface 22a of the spring receiving member 22 is in contact with the first stepped surface 18. An annular spring accommodating groove 22c is formed on the other end surface 22b of the spring receiving member 22. A circular hole-shaped insertion hole 22h is formed in the central portion of the spring receiving member 22.

The cylinder chamber 23 is partitioned in the through hole 12 by one end surface 22a of the spring receiving member 22, an inner peripheral surface of the cylinder hole 15, and a second stepped surface 19. Therefore, the body 11 has a cylinder chamber 23. An annular piston 24 is housed in the cylinder chamber 23. An annular piston packing 25 is mounted on the outer peripheral surface of the piston 24. The piston packing 25 seals between the outer peripheral surface of the piston 24 and the inner peripheral surface of the cylinder hole 15.

The piston 24 divides the cylinder chamber 23 into a first pressure acting chamber 26 on the spring receiving member 22 side and a second pressure acting chamber 27 on the second stepped surface 19 side. A first fluid supply / discharge port 28 communicating with the first pressure acting chamber 26 is formed near the spring receiving member 22 on the outer peripheral wall of the body 11. Then, fluid is supplied to and discharged from the first pressure action chamber 26 by the first fluid supply / discharge port 28. Further, a second fluid supply / discharge port 29 communicating with the second pressure acting chamber 27 is formed near the second stepped surface 19 on the outer peripheral wall of the body 11. Then, fluid is supplied to and discharged from the second pressure action chamber 27 by the second fluid supply / discharge port 29. Therefore, the fluid is supplied and discharged to the cylinder chamber 23. The piston 24 reciprocates in the cylinder chamber 23 by supplying and discharging fluid to the first pressure acting chamber 26 and the second pressure acting chamber 27. Therefore, the piston 24 reciprocates in the cylinder chamber 23 by the fluid supplied to and discharged from the cylinder chamber 23.

The piston 24 is integrated with a piston rod 30 extending in the axial direction of the body 11 from the end surface of the piston 24 opposite to the spring receiving member 22. Therefore, the piston rod 30 moves integrally with the piston 24. The piston rod 30 passes through the rod insertion hole 16 and the accommodating hole 17 and projects from the other end surface 11b of the body 11. The tip of the piston rod 30 on the opposite side of the piston 24 is located between the pair of support portions 21. Therefore, the piston rod 30 can appear and disappear with respect to the body 11 between the pair of support portions 21.

The rod packing 31 is mounted in the seal mounting groove 16a. The rod packing 31 seals between the inner peripheral surface of the rod insertion hole 16 and the outer peripheral surface of the piston rod 30. Further, a retaining member 32 is arranged in the accommodating hole 17. The retaining member 32 prevents the rod packing 31 from coming off from the seal mounting groove 16a.

The gripping device 10 includes a pair of master jaws 33 that open and close with the reciprocating movement of the piston 24. Further, the gripping device 10 includes a guide plate 34 that guides the pair of master jaws 33 in the direction of contacting and separating from each other. The guide plate 34 is attached to the end of the pair of support portions 21 opposite to the other end surface 11b of the body 11. A guide recess 34a is formed on the end surface of the guide plate 34 on the side opposite to the pair of support portions 21 to guide the pair of master jaws 33 in the direction of contacting and separating from each other. Further, the guide plate 34 is formed with a pair of through holes 34h for levers.

The gripping device 10 includes a pair of levers 35. Each lever 35 has a substantially L-shaped plate shape. A part of each lever 35 is arranged between the pair of support portions 21. A U-shaped engaging groove 35a is formed at one end of each lever 35. The engaging groove 35a of each lever 35 is engaged with the engaging shaft 36 provided at the tip of the piston rod 30. Further, a support shaft 37 penetrates through the L-shaped bent portion of each lever 35. Each support shaft 37 is fixed to the pair of support portions 21 in a state of being bridged over the pair of support portions 21. Then, the piston rod 30 performs an infestation operation with respect to the body 11, so that each lever 35 rotates about each support shaft 37 as a rotation center.

The other end of each lever 35 passes through the through hole 34h for each lever and protrudes from the end face on the guide plate 34 opposite to the pair of support portions 21. An engaging element 38 is provided at the other end of each lever 35. Then, the engaging element 38 of each lever 35 is inserted into the accommodating recess 33h formed in each master jaw 33. As a result, the engaging elements 38 and the accommodating recesses 33h are hooked to each other. Each master jaw 33 is connected to the tip end portion of each lever 35 by hooking each engaging element 38 and each accommodating recess 33h.

As shown in FIG. 3, when the fluid is supplied from the second fluid supply / discharge port 29 to the second pressure action chamber 27, the piston 24 starts to move toward the spring receiving member 22, and the first pressure action chamber 26 The fluid is discharged to the outside through the first fluid supply / discharge port 28, and the piston 24 moves toward the spring receiving member 22. As a result, the piston rod 30 moves in the direction of being immersed in the body 11. As the piston rod 30 moves in the immersion direction with respect to the body 11, one end of the pair of levers 35 is pulled into the piston rod 30 via the engaging shaft 36, and each lever 35 rotates each support shaft 37. Each engaging element 38 rotates in a direction approaching each other as a moving center. By the movement of each of the engagers 38 in the direction of approaching each other, the pair of master jaws 33 move in the direction of approaching each other and grip the work W1.

As shown in FIG. 1, when the fluid is supplied from the first fluid supply / discharge port 28 to the first pressure action chamber 26, the piston 24 starts to move toward the second step surface 19, and the second pressure action chamber 27 Is discharged to the outside through the second fluid supply / discharge port 29, and the piston 24 moves toward the second step surface 19. As a result, the piston rod 30 moves in the direction of projecting with respect to the body 11. As the piston rod 30 moves in the protruding direction with respect to the body 11, one end of the pair of levers 35 is pushed into the piston rod 30 via the engaging shaft 36, and each lever 35 rotates each support shaft 37. As the center of movement, the engaging elements 38 rotate in a direction in which they are separated from each other. By moving the engaging elements 38 in the directions away from each other, the pair of master jaws 33 move in the directions away from each other, and the gripping state of the work W1 is released.

As shown in FIG. 2, a disk-shaped head cover 39 is attached to the female screw hole 13. Therefore, the head cover 39 is attached to one end of the body 11 in the axial direction. A male screw portion 39a screwed into the female screw hole 13 is formed on the outer peripheral surface of the head cover 39. Therefore, the head cover 39 has a male screw portion 39a that is screwed into the body 11. The sensor accommodating chamber 40 is partitioned in the through hole 12 by the head cover 39, the inner peripheral surface of the sensor accommodating hole 14, and the other end surface 22b of the spring receiving member 22. Therefore, the body 11 has a sensor accommodating chamber 40.

The gripping device 10 includes an LVDT sensor 50 that detects the positions of a pair of master jaws 33. The LVDT sensor 50 reciprocates integrally with the cylindrical sensor case main body 51, the primary coil 61 wound around the sensor case main body 51, the two secondary coils 62, and the piston 24, and is attached to the sensor case main body 51. On the other hand, it has a core shaft 63 that can appear and disappear.

The sensor case main body 51 has a bottomed cylindrical main body 52 made of resin. The main body 52 has a disk-shaped bottom wall 52a and a cylindrical peripheral wall 52b extending from the outer peripheral portion of the bottom wall 52a. The inner diameter of the peripheral wall 52b is the same as the hole diameter of the insertion hole 22h of the spring receiving member 22. Further, the main body portion 52 has an annular flange 52c that protrudes outward from an end portion of the peripheral wall 52b opposite to the bottom wall 52a. In the sensor case main body 51, the primary coil 61 and the two secondary coils 62 are resin-molded in the main body 52, and the primary coil 61 and the two secondary coils 62 are embedded in the peripheral wall 52b of the main body 52. .. The primary coil 61 and the two secondary coils 62 are arranged side by side in the axial direction of the main body 52. In the axial direction of the main body 52, the primary coil 61 is arranged between the two secondary coils 62.

Further, the sensor case main body 51 has a cylindrical covering member 53 that covers the outer peripheral surface of the peripheral wall 52b of the main body 52. The covering member 53 is made of iron, for example. Further, the sensor case main body 51 has a cylindrical case member 54 that covers the outer peripheral surface of the covering member 53. The case member 54 is made of, for example, aluminum. The outer diameter of the case member 54 is substantially the same as the outer diameter of the flange 52c. The end face of the case member 54 on the flange 52c side is in contact with the flange 52c. Further, the end surface of the case member 54 on the head cover 39 side is in contact with the head cover 39.

The outer diameter of the flange 52c and the outer diameter of the case member 54 are slightly smaller than the hole diameter of the small diameter hole 14a of the sensor accommodating hole 14. The sensor case main body 51 is housed in the sensor storage chamber 40. The flange 52c is arranged inside the small diameter hole 14a. The axis of the peripheral wall 52b of the main body 52 coincides with the axis of the insertion hole 22h of the spring receiving member 22.

The core shaft 63 is formed with a male screw 63a screwed into a female screw hole 24h formed on the end surface of the piston 24 on the spring receiving member 22 side. The core shaft 63 is integrated with the piston 24 in a state of extending in the axial direction of the body 11 from the end surface of the piston 24 on the spring receiving member 22 side by screwing the male screw 63a into the female screw hole 24h. .. A nut 64 is screwed onto the male screw 63a to prevent the male screw 63a from loosening with respect to the female screw hole 24h.

The core shaft 63 passes through the insertion hole 22h of the spring receiving member 22 from the cylinder chamber 23 and is inserted inside the peripheral wall 52b of the main body 52. The outer diameter of the core shaft 63 is smaller than the inner diameter of the peripheral wall 52b and the hole diameter of the insertion hole 22h of the spring receiving member 22. The LVDT sensor 50 is built in the body 11 in a state of being arranged coaxially with the piston 24.

An AC voltage is applied to the primary coil 61. An induced voltage is generated in each of the secondary coils 62 by the core shaft 63 reciprocating inside each of the secondary coils 62 as the piston 24 reciprocates.

The urging member 65 is housed in the spring accommodating groove 22c of the spring receiving member 22. The urging member 65 is, for example, a wave washer. The urging member 65 is in contact with the end surface of the main body 52 opposite to the bottom wall 52a. Therefore, the urging member 65 abuts against the sensor case main body 51 around the axis of the sensor case main body 51 and urges the sensor case main body 51 toward the head cover 39. The urging member 65 cooperates with the head cover 39 to sandwich the sensor case main body 51.

An annular sealing member 66 is mounted on the outer peripheral surface of the flange 52c. The sealing member 66 seals between the outer peripheral surface of the flange 52c and the inner peripheral surface of the small diameter hole 14a. Therefore, a sealing member 66 is provided on the outer peripheral surface of the sensor case main body 51 to seal between the outer peripheral surface of the sensor case main body 51 and the inner peripheral surface of the body 11 to prevent fluid from leaking from the cylinder chamber 23. ing.

The gripping device 10 further includes a rotation stop mechanism 70 that prevents rotation of the sensor case body 51 with respect to the body 11. The rotation stop mechanism 70 is composed of a bolt 71 screwed into the outer peripheral surface of the case member 54, and a hole 72 formed in the body 11 and in which the head portion 71a of the bolt 71 is arranged inside.

As shown in FIG. 4, a recess 11c is formed on the outer surface of the outer peripheral wall of the body 11. The hole 72 is formed in the bottom surface 11d of the recess 11c. The hole 72 communicates with the large-diameter hole 14b of the sensor accommodating hole 14. The hole 72 has an elliptical hole shape when viewed in a plan view. The longitudinal direction of the hole 72 coincides with the axial direction of the body 11. The inner peripheral edge of the hole 72 connects a pair of long side edges 72a extending parallel to each other in the longitudinal direction of the hole 72 and ends of the pair of long side edges 72a on the spring receiving member 22 side, and is curved in an arc shape. It is formed of one curved edge 72b and a second curved edge 72c that connects the ends of the pair of long side edges 72a on the head cover 39 side and curves in an arc shape.

As shown in FIG. 2, in a state where the flange 52c is arranged inside the small diameter hole 14a and the sensor case main body 51 is sandwiched between the urging member 65 and the head cover 39, the head 71a of the bolt 71 is , Located near the first curved edge 72b of the hole 72. At this time, in the axial direction of the body 11, the distance L1 between the head portion 71a of the bolt 71 and the second curved edge 72c of the hole 72 is larger than the distance L2 from the tapered surface 14c to the seal member 66. ..

As shown in FIG. 4, a wiring insertion hole 11h is formed in the bottom surface 11d of the recess 11c. As shown in FIG. 2, the wiring insertion hole 11h is located closer to the head cover 39 than the hole 72 and communicates with the large diameter hole 14b of the sensor accommodating hole 14. Further, the case member 54 is formed with a notch 54k. The wiring insertion hole 11h and the notch 54k overlap in a direction orthogonal to the axial direction of the body 11. The electrical wiring 73 drawn out from the primary coil 61 and the two secondary coils 62 passes through the notch 54k and the wiring insertion hole 11h and extends into the recess 11c.

As shown in FIG. 1, an amplifier 74 is mounted on the outer surface of the outer peripheral wall of the body 11. Therefore, the amplifier 74 is integrated with the gripping device 10. The amplifier 74 is attached to the outer surface of the outer peripheral wall of the body 11 with the recess 11c closed. The ends of the electrical wiring 73 opposite to the primary coil 61 and the two secondary coils 62 are electrically connected to the amplifier 74. The amplifier 74 is electrically connected to the external control device 75 via the connector 74a. The amplifier 74 amplifies the induced voltage output from each secondary coil 62. Then, the voltage amplified by the amplifier 74 is supplied to the external control device 75 via the connector 74a.

Next, the operation of this embodiment will be described.
The reciprocating movement of the core shaft 63 with the reciprocating movement of the piston 24 causes a difference in the induced voltage generated in each of the secondary coils 62. This difference in induced voltage changes depending on the position of the core shaft 63. Further, the moving amount of the pair of master jaws 33 and the moving amount of the piston 24 are in a proportional relationship. Therefore, the external control device 75 detects the amount of change in the difference between the induced voltages supplied from each secondary coil 62 via the electrical wiring 73 and the amplifier 74, thereby moving the core shaft 63, that is, the piston 24. The movement amount can be detected, and as a result, the movement amount of the pair of master jaws 33 can be detected. According to this, the positions of the pair of master jaws 33 can be detected linearly, and the positions of the pair of master jaws 33 can be detected with high accuracy.

Further, the external control device 75 detects the position of the pair of master jaws 33 when the pair of master jaws 33 is gripping the work W1, and the work is based on the position information of the pair of master jaws 33. The dimensions of W1 can also be measured. Therefore, the LVDT sensor 50 of the present embodiment also functions as a length measuring sensor used for measuring the dimensions of the work W1.

As shown in FIG. 5, by the way, for example, during maintenance, the head cover 39 is attached to and removed from the body 11. At this time, when the end surface of the case member 54 on the head cover 39 side and the head cover 39 are in contact with each other and the male screw portion 39a of the head cover 39 is screwed or retracted into the female screw hole 13, the sensor case main body 51 moves the head cover 39. I try to take him around with me. At this time, the head 71a of the bolt 71 comes into contact with one of the pair of long side edges 72a of the hole 72, so that the sensor case body 51 is prevented from rotating with respect to the body 11.

For example, when removing the sensor case main body 51 from the body 11 such as during maintenance, first, the head cover 39 is removed from the body 11 and the amplifier 74 is removed from the outer surface of the outer peripheral wall of the body 11. Then, the head 71a of the bolt 71 is moved toward the second curved edge 72c until the head 71a of the bolt 71 abuts on the second curved edge 72c of the hole 72. Then, the sensor case main body 51 moves toward the female screw hole 13, and the flange 52c is located inside the large diameter hole 14b from the small diameter hole 14a via the tapered surface 14c. As a result, the seal between the outer peripheral surface of the flange 52c and the inner peripheral surface of the small diameter hole 14a in the seal member 66 is released, and the sliding resistance between the seal member 66 and the body 11 is reduced. As a result, the sensor case body 51 moves smoothly in the body 11 in the axial direction, and the sensor case body 51 can be easily removed from the body 11. Then, the sensor case main body 51 is removed from the body 11 by removing the bolt 71 from the case member 54 and pulling out the sensor case main body 51 from the through hole 12.

In the above embodiment, the following effects can be obtained.
(1) The gripping device 10 abuts against the sensor case main body 51 around the axis of the sensor case main body 51 and urges the sensor case main body 51 toward the head cover 39 to cooperate with the head cover 39 to cooperate with the sensor case. It includes an urging member 65 that sandwiches the main body 51. According to this, since the sensor case main body 51 is sandwiched between the urging member 65 and the head cover 39 that come into contact with the periphery of the axis of the sensor case main body 51, the sensor case main body 51 is with respect to the axis of the core shaft 63. It is possible to prevent the body 11 from being arranged in the body 11 in a tilted state. Therefore, the movement of the core shaft 63 with respect to the sensor case body 51 can be made smooth.

(2) On the outer peripheral surface of the sensor case main body 51, an annular sealing member 66 that seals between the outer peripheral surface of the sensor case main body 51 and the inner peripheral surface of the body 11 to suppress leakage of fluid from the cylinder chamber 23. Is provided. According to this, in the direction orthogonal to the axis of the sensor case main body 51, the position of the sensor case main body 51 in the body 11 is determined by the elastic force of the annular sealing member 66 that suppresses the leakage of fluid from the cylinder chamber 23. Can be positioned using. Therefore, it is possible to prevent the axis of the sensor case body 51 from being displaced with respect to the axis of the core shaft 63, so that the movement of the core shaft 63 with respect to the sensor case body 51 can be made smoother.

(3) The head cover 39 has a male screw portion 39a that is screwed into the body 11. Further, the gripping device 10 further includes a rotation stop mechanism 70 for preventing rotation of the sensor case main body 51 with respect to the body 11. According to this, for example, as compared with the case where the head cover 39 is attached to the body 11 by press fitting, the assembling property of the head cover 39 to the body 11 can be improved. Further, even when the head cover 39 needs to be removed from the body 11 at the time of maintenance, for example, the head cover 39 is attached to the body 11 by press fitting as compared with the case where the head cover 39 is attached to the body 11 by press fitting. Can be easily removed. Further, the rotation stop mechanism 70 can prevent the sensor case main body 51 from rotating together with the head cover 39 when the head cover 39 is attached to or removed from the body 11. Therefore, it is possible to avoid problems such as the electrical wiring 73 connected to each of the primary coil 61 and the secondary coil 62 being pulled and damaged as the sensor case main body 51 rotates. be able to.

(4) When removing the sensor case body 51 from the body 11 such as during maintenance, the head 71a of the bolt 71 is second curved until the head 71a of the bolt 71 abuts on the second curved edge 72c of the hole 72. Move towards edge 72c. As a result, the sensor case main body 51 can move toward the female screw hole 13 so that the flange 52c can be positioned inside the large diameter hole 14b from the small diameter hole 14a via the tapered surface 14c. As a result, the seal between the outer peripheral surface of the flange 52c and the inner peripheral surface of the small diameter hole 14a in the seal member 66 is released, and the sliding resistance between the seal member 66 and the body 11 can be reduced. The movement of the sensor case body 51 in the body 11 in the axial direction becomes smooth, and the sensor case body 51 can be easily removed from the body 11.

(5) According to the present embodiment, since the movement of the core shaft 63 with respect to the sensor case main body 51 is smoothly performed, the positions of the pair of master jaws 33 on the external control device 75 can be detected with high accuracy.

The above embodiment can be modified and implemented as follows. The above embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

As shown in FIG. 6, the rotation stop mechanism 70 is composed of a bolt 81 screwed into the body 11 and a hole 82 formed in the sensor case main body 51 and in which the shaft portion 81a of the bolt 81 is arranged inside. You may be. A female screw hole 11e into which the shaft portion 81a of the bolt 81 is screwed is formed in the bottom surface 11d of the recess 11c. The covering member 53 is formed with a groove 53e through which the shaft portion 81a of the bolt 81 is inserted. The hole 82, the groove 53e, and the female screw hole 11e overlap in a direction orthogonal to the axial direction of the body 11. Then, the tip of the shaft portion 81a of the bolt 81 that has passed through the female screw hole 11e and the groove 53e is inserted into the hole 82. According to this, when the sensor case main body 51 tries to rotate together with the head cover 39, the inner peripheral surface of the hole 82 comes into contact with the tip end portion of the shaft portion 81a of the bolt 81, so that the sensor case main body 51 rotates with respect to the body 11. Is prevented. In the embodiment shown in FIG. 6, the outer diameter of the piston 24 is smaller than that in the above embodiment in order to reduce the size of the gripping device 10. Along with this, the outer diameter of the sensor case main body 51 is also reduced. Specifically, the sensor case main body 51 of the embodiment shown in FIG. 6 has a configuration in which the case member 54 described in the above embodiment is omitted.

In the embodiment, the annular seal member 66 that suppresses the leakage of fluid from the cylinder chamber 23 is not provided on the outer peripheral surface of the sensor case main body 51, for example, the outer peripheral surface of the spring receiving member 22 and the spring receiving member 22. It may be provided between the other end surface 22b of the member 22 and the sensor case main body 51, respectively.

-In the embodiment, the head cover 39 may be attached to the body 11 by press fitting.
-In the embodiment, the urging member 65 may be, for example, a coil spring.

In the embodiment, the LVDT sensor 50 does not have to have the primary coil 61 and the two secondary coils 62 arranged side by side in the axial direction of the main body 52, for example, the two secondary coils 62. The primary coil 61 may be arranged on the inner peripheral side of the above.

-In the embodiment, the amplifier 74 may not be mounted on the outer surface of the outer peripheral wall of the body 11. In short, the amplifier 74 does not have to be integrated with the gripping device 10.
-In the embodiment, the body 11 is not limited to a square cylinder shape, and may be, for example, a cylindrical shape.

10 ... Gripping device, 11 ... Body, 23 ... Cylinder chamber, 24 ... Piston, 33 ... Master jaw, 39 ... Head cover, 39a ... Male thread, 50 ... LVDT sensor, 51 ... Sensor case body, 61 ... Primary coil, 62 ... Secondary coil, 63 ... core shaft, 65 ... urging member, 66 ... seal member, 70 ... rotation stop mechanism.

Claims (3)

A tubular body with a cylinder chamber to which fluid is supplied and discharged,
A piston housed in the cylinder chamber and reciprocated by a fluid supplied to and discharged from the cylinder chamber,
A head cover attached to the axial end of the body,
A pair of master jaws that open and close with the reciprocating movement of the piston,
It is equipped with an LVDT sensor that is built in the body in a state of being coaxially arranged with the piston and that detects the position of the pair of master jaws.
The LVDT sensor is
With the tubular sensor case body
A primary coil and two secondary coils wound around the sensor case body,
A gripping device having a core shaft that reciprocates integrally with the piston and can appear and disappear with respect to the sensor case body.
A spring receiving member arranged coaxially with the sensor case main body and located on the opposite side of the sensor case main body from the head cover.
It is provided with an urging member that is arranged coaxially with the sensor case body and that sandwiches the sensor case body in cooperation with the head cover .
One end of the urging member is in contact with the spring receiving member, the other end is in contact with the periphery of the axis of the sensor case body at the end surface of the sensor case body, and the sensor case body is directed toward the head cover. A gripping device characterized in that it is urged along the axis of. An annular sealing member is provided on the outer peripheral surface of the sensor case main body to seal between the outer peripheral surface of the sensor case main body and the inner peripheral surface of the body to prevent fluid from leaking from the cylinder chamber. The gripping device according to claim 1, wherein the gripping device is provided. The head cover has a male threaded portion that is screwed into the body.
The gripping device according to claim 1 or 2, further comprising a rotation stop mechanism for preventing rotation of the sensor case body with respect to the body.

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