Air chuck

Abstract

The present invention is provided with: separation urging air chambers (60a, 60d) for urging a plurality of finger sections (30, 32) in directions in which the finger sections (30, 32) are separated from each other; proximity biasing air chambers (60b, 60c) that bias the plurality of finger-shaped parts in a direction in which the plurality of finger-shaped parts approach each other; a first solenoid valve (84) for supplying and discharging air in the separation biasing air chamber; and a second solenoid valve (86) for supplying and discharging air approaching the biasing air chamber, a first check valve (78) is disposed in the middle of a flow path connecting the first solenoid valve and the supply port (72), a second check valve (80) is disposed in the middle of a flow path connecting the second solenoid valve and the supply port, and the first solenoid valve and the second solenoid valve are attached to a valve body (66).

Description

Technical Field

[0001] The present invention relates to an air chuck having a plurality of fingers that can be driven by air. Background Art

[0002] Conventionally, there is known an air chuck that has a plurality of fingers that can be opened and closed by air and that can hold, convey, and release a workpiece. In a case where a plurality of workpieces are densely placed on the ground, for example, if the workpieces are approached with the plurality of fingers widely opened, there is a concern that the fingers may contact a workpiece adjacent to the workpiece to be held, thereby obstructing the holding of the workpiece. If an air chuck that can adjust the degree of opening of the plurality of fingers is used, such a problem will not occur.

[0003] Japanese Patent Publication No. 2008-249027 describes a positioning control mechanism for a double-acting cylinder that can arbitrarily position the cylinder's operating position. The positioning control mechanism includes a sensor for measuring the piston's operating position, and when the piston reaches the target position, all electromagnetic valves for supplying and exhausting air to each pressure chamber of the double-acting cylinder are disconnected, and the air in each pressure chamber is sealed.

[0004] If the positioning control mechanism of the double-acting air cylinder is applied to an air chuck, the opening degree of the plurality of fingers can be adjusted, so that even when a plurality of workpieces are densely placed on the ground, one workpiece can be gripped.

[0005] However, even if all the solenoid valves for supplying and exhausting air to each pressure chamber are disconnected, it is difficult to completely eliminate air leakage in the solenoid valves, so the mutual spacing of the plurality of finger-shaped portions may not be properly maintained. In addition, there is a possibility that air leakage may occur in the sealing portion of the piston, etc. due to changes over time, so the mutual spacing of the plurality of finger-shaped portions may not be properly maintained. Summary of the invention

[0006] The object of the present invention is to solve the above technical problems through a compact structure.

[0007] The present invention relates to an air chuck, which comprises a cylinder, a valve body and a plurality of finger-shaped parts, and the air chuck comprises a separation force air chamber, an approach force air chamber, a first solenoid valve, a second solenoid valve and a sensor. The separation force air chamber applies force to the plurality of finger-shaped parts in a direction of separation from each other, and the approach force air chamber applies force to the plurality of finger-shaped parts in a direction of approaching each other. The first solenoid valve supplies and exhausts air in the separation force air chamber, and the second solenoid valve supplies and exhausts air in the approach force air chamber. The sensor detects the intervals between the plurality of finger-shaped parts, and the first solenoid valve and the second solenoid valve are controlled so that the intervals between the plurality of finger-shaped parts detected by the sensor become target intervals. The separation force air chamber and the approach force air chamber are arranged in the cylinder, and the first solenoid valve and the second solenoid valve are installed in the valve body. A first check valve is arranged in the middle of a flow path connecting the first solenoid valve and a supply port of the valve body, and a second check valve is arranged in the middle of a flow path connecting the second solenoid valve and the supply port.

[0008] Since the air chuck of the present invention has the first check valve and the second check valve, air can be immediately replenished even if air leakage occurs in a specified operating state, and the mutual intervals of the plurality of finger-shaped parts are maintained at a specified value. In addition, since the separation force air chamber and the proximity force air chamber are arranged in the cylinder body, and the first solenoid valve and the second solenoid valve are installed in the valve body, the necessary air circuit can be compactly arranged.

[0009] The above-mentioned objects, features and advantages will be easily understood from the following description of the embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is an external view of an air chuck according to an embodiment of the present invention.

[0011] Figure 2 yes Figure 1 Front view of the air chuck.

[0012] Figure 3 It is along Figure 2 A cross-sectional view of the air chuck taken along line III-III.

[0013] Figure 4 It is along Figure 2 A cross-sectional view of the air chuck taken along line IV-IV.

[0014] Figure 5 In order to understand the structure of the finger synchronization mechanism, Figure 1 A diagram of a portion of an air chuck expanded into parts or groups of parts.

[0015] Figure 6 In order to understand the structure of the valve body, Figure 1 An illustration of an air chuck expanded into parts or groups of parts.

[0016] Figure 7 It is along Figure 2 A cross-sectional view of the air chuck taken along line VII-VII.

[0017] Figure 8 It is along Figure 2 A cross-sectional view of the air chuck taken along line VIII-VIII.

[0018] Fig. 9 It is conceptually expressed Figure 1 Circuit diagram of the fluid circuit of the air chuck.

[0019] Fig.10 It is conceptually expressed Figure 1 Circuit diagram of the fluid circuit for the opening action of the air chuck.

[0020] Fig.11 It is conceptually expressed Figure 1 Circuit diagram of the fluid circuit for the closing action of the air chuck.

[0021] Fig.12 It is conceptually expressed Figure 1 Circuit diagram of the fluid circuit with the intermediate stop of the air chuck. DETAILED DESCRIPTION

[0022] like Figure 1 and Figure 2 As shown in FIG. 1 , the air chuck 10 according to the embodiment of the present invention includes a cylinder 12, a first finger 30, a second finger 32, and a valve body 66. In addition, the air chuck 10 includes a finger synchronization mechanism, an air drive unit, and an electromagnetic valve control unit. The air chuck 10 is used by being mounted on the top of a robot arm, for example. Hereinafter, when using words related to the up and down directions, the direction in which the valve body 66 is arranged relative to the cylinder 12 is defined as "up".

[0023] like Figure 3 and Figure 4 As shown, the rectangular parallelepiped cylinder body 12 has a first cylinder hole 14 and a second cylinder hole 16. The first cylinder hole 14 and the second cylinder hole 16 penetrate along the length direction (X direction) of the cylinder body 12. One end of the first cylinder hole 14 is closed by a first end cover 18a, and the other end of the first cylinder hole 14 is closed by a second end cover 18b. One end of the second cylinder hole 16 is closed by a third end cover 18c, and the other end of the second cylinder hole 16 is closed by a fourth end cover 18d. These end covers 18a to 18d are fixed to the cylinder body 12 by a C-shaped stopper wheel 20.

[0024] like Figure 5As shown, the cylinder block 12 has a recess 22 for accommodating a pinion 38 described later. The recess 22 is open on the lower surface of the cylinder block 12 and is connected to the first cylinder hole 14 and the second cylinder hole 16. A guide rail 28 is mounted on the lower surface of the cylinder block 12. The side surface of the cylinder block 12 has a sensor groove 24 for mounting a position sensor 88 described later. In addition, the component indicated by the reference numeral 36 is a bolt for mounting the guide rail 28 to the cylinder block 12.

[0025] The first finger 30 and the second finger 32 are slidably supported on the guide rail 28 (see FIG. 2 ) via a plurality of balls 34 . Figure 4 Accessories (not shown) for holding a workpiece are mounted on the first finger portion 30 and the second finger portion 32 .

[0026] The finger synchronization mechanism is composed of a pinion 38, a first rack 40, a second rack 42, and a pair of joints 44. The pinion 38 disposed in the recess 22 of the cylinder 12 is supported by the cylinder 12 and the guide rail 28 to be rotatable (rotatable) about its axis.

[0027] The cylindrical first rack 40 is inserted through the first cylinder hole 14 and supported so as to be movable in the X direction. The cylindrical second rack 42 is inserted through the second cylinder hole 16 and supported so as to be movable in the X direction. The side surface of the first rack 40 has a tooth portion 40a that meshes with the tooth 38a of the pinion 38, and has a groove 40b for engaging with one side connector 44. The side surface of the second rack 42 has a tooth portion 42a that meshes with the tooth 38a of the pinion 38, and has a groove 42b for engaging with the other side connector 44. A pair of magnets 48 (see FIG. 2 ) are respectively mounted on the first rack 40 and the second rack 42. Figure 3 ).

[0028] When the first rack 40 moves in the X1 direction, the pinion 38 rotates in the specified direction, and the second rack 42 moves in the X2 direction. When the first rack 40 moves in the X2 direction, the pinion 38 rotates in the direction opposite to the specified direction, and the second rack 42 moves in the X1 direction. That is, the first rack 40 and the second rack 42 move in opposite directions synchronously with each other.

[0029] The convex portion 44a formed on one side of the joint 44 engages with the concave groove 40b of the first rack 40, and the convex portion 44a formed on the other side of the joint 44 engages with the concave groove 42b of the second rack 42. Thus, the joint 44 on one side is integrated with the first rack 40 and moves in the X direction, and the joint 44 on the other side is integrated with the second rack 42 and moves in the X direction. The joint 44 on one side is attached to the first finger 30, and the joint 44 on the other side is attached to the second finger 32. Therefore, the first finger 30 and the second finger 32 are synchronously moved in opposite directions by the finger synchronization mechanism.

[0030] The air drive unit includes a first piston 52, a second piston 54, a third piston 56 and a fourth piston 58 (see Figure 3 ). The first piston 52 connected to one end of the first rack 40 by a first bolt 52b is slidably arranged in the first cylinder hole 14. The second piston 54 connected to the other end of the first rack 40 by a second bolt 54b is slidably arranged in the first cylinder hole 14. The third piston 56 connected to one end of the second rack 42 by a third bolt 56b is slidably arranged in the second cylinder hole 16. The fourth piston 58 connected to the other end of the second rack 42 by a fourth bolt 58b is slidably arranged in the second cylinder hole 16.

[0031] A first air chamber 60a is formed between the first piston 52 and the first end cover 18a. The first air chamber 60a is kept airtight from the outside by the piston liner 52a installed on the first piston 52, the gasket 62a installed on the first end cover 18a, and the gasket 64a installed on the first piston 52. A second air chamber 60b is formed between the second piston 54 and the second end cover 18b. The second air chamber 60b is kept airtight from the outside by the piston liner 54a installed on the second piston 54, the gasket 62b installed on the second end cover 18b, and the gasket 64b installed on the second piston 54. The pressure area of ​​the first piston 52 acted on by the air of the first air chamber 60a is equal to the pressure area of ​​the second piston 54 acted on by the air of the second air chamber 60b.

[0032] A third air chamber 60c is formed between the third piston 56 and the third end cover 18c. The third air chamber 60c is kept airtight from the outside by the piston liner 56a installed on the third piston 56, the gasket 62c installed on the third end cover 18c, and the gasket 64c installed on the third piston 56. A fourth air chamber 60d is formed between the fourth piston 58 and the fourth end cover 18d. The fourth air chamber 60d is kept airtight from the outside by the piston liner 58a installed on the fourth piston 58, the gasket 62d installed on the fourth end cover 18d, and the gasket 64d installed on the fourth piston 58. The pressure area of ​​the third piston 56 acted on by the air of the third air chamber 60c is equal to the pressure area of ​​the fourth piston 58 acted on by the air of the fourth air chamber 60d.

[0033] The first air chamber 60a and the fourth air chamber 60d communicate with each other via a first air passage 26a formed in the cylinder 12 (see Fig. 9 ). The second air chamber 60b and the third air chamber 60c are connected to each other via the second air passage 26b formed in the cylinder 12. Fig. 9In the figure, for the sake of convenience, the first air chamber 60a and the fourth air chamber 60d are shown indistinguishably from each other. In addition, for the sake of convenience, the second air chamber 60b and the third air chamber 60c are shown indistinguishably from each other.

[0034] When air is supplied to the first air chamber 60a and the fourth air chamber 60d, the first finger 30 and the second finger 32 are urged in directions away from each other. The first air chamber 60a and the fourth air chamber 60d are equivalent to the "separation urging air chamber" of the present invention. When air is supplied to the second air chamber 60b and the third air chamber 60c, the first finger 30 and the second finger 32 are urged in directions toward each other. The second air chamber 60b and the third air chamber 60c are equivalent to the "approach urging air chamber" of the present invention.

[0035] The valve body 66 is composed of a first plate 68 and a second plate 70. The first plate 68 is mounted on the upper surface of the cylinder body 12. The second plate 70 is mounted on the upper surface of the first plate 68. The side surface of the first plate 68 is provided with a first exhaust port 74 and a second exhaust port 76 (see Figure 8 A first variable throttle valve 74a is provided in the first exhaust port 74 (see Fig. 9 The speed of the air discharged from the first exhaust port 74 can be adjusted by the first variable throttle valve 74a. The second exhaust port 76 is provided with a second variable throttle valve 76a (see Fig. 9 The speed of the air discharged from the second exhaust port 76 can be adjusted by the second variable throttle valve 76a. The side surface of the second plate 70 is provided with a single supply port 72 for receiving air from the air supply source 50.

[0036] The solenoid valve control unit includes a first solenoid valve 84, a second solenoid valve 86, a position sensor 88 and a controller (not shown). The first solenoid valve 84 and the second solenoid valve 86 are installed on the side of the first plate 68 away from the first exhaust port 74 and the second exhaust port 76 (see Figure 8 ) The first solenoid valve 84 and the second solenoid valve 86 are configured as three-port solenoid valves that can be switched between two positions.

[0037] like Fig. 9 As shown, the first port 84a of the first solenoid valve 84 communicates with the first air passage 26a of the cylinder 12 via the first air passage 68a formed in the first plate 68. The second port 84b of the first solenoid valve 84 is connected to the supply port 72 via the first supply passage 68c formed in the first plate 68 and the first supply passage 70a formed in the second plate 70. The third port 84c of the first solenoid valve 84 is connected to the first exhaust port 74 via the first exhaust passage 68e formed in the first plate 68.

[0038] like Figure 7As shown, a first check valve 78 is disposed at the end of the first supply passage 68c of the first plate 68 connected to the first supply passage 70a of the second plate 70. The first check valve 78 includes a movable body 78a and a spring 78b (see Figure 6 ). The first check valve 78 allows the flow of air from the supply port 72 toward the second port 84b of the first solenoid valve 84, and blocks the flow of air from the second port 84b of the first solenoid valve 84 toward the supply port 72. Since the first check valve 78 is arranged at a portion including the joint surface of the first plate 68 and the second plate 70, the structure and arrangement of the first check valve 78 including the seating surface of the movable body 78a become simple.

[0039] The first solenoid valve 84 switches to the first position when energized (on), and switches to the second position when not energized (off). When the first solenoid valve 84 is in the first position, the first port 84a is connected to the second port 84b and is disconnected from the third port 84c. When the first solenoid valve 84 is in the second position, the first port 84a is connected to the third port 84c and is disconnected from the second port 84b.

[0040] The first port 86a of the second solenoid valve 86 communicates with the second air passage 26b of the cylinder 12 via the second air passage 68b formed in the first plate 68. The second port 86b of the second solenoid valve 86 is connected to the supply port 72 via the second supply passage 68d formed in the first plate 68 and the second supply passage 70b formed in the second plate 70. The third port 86c of the second solenoid valve 86 is connected to the second exhaust port 76 via the second exhaust passage 68f formed in the first plate 68.

[0041] A second check valve 80 is disposed at the end of the second supply passage 68d of the first plate 68 connected to the second supply passage 70b of the second plate 70. The second check valve 80 includes a movable body 80a and a spring 80b (see Figure 6 The second check valve 80 allows the flow of air from the supply port 72 toward the second port 86b of the second solenoid valve 86, and blocks the flow of air from the second port 86b of the second solenoid valve 86 toward the supply port 72. Since the second check valve 80 is arranged at a portion including the joint surface of the first plate 68 and the second plate 70, the structure and arrangement of the second check valve 80 including the seating surface of the movable body 80a become simple.

[0042] The second solenoid valve 86 switches to the first position when energized (on), and switches to the second position when not energized (off). When the second solenoid valve 86 is in the first position, the first port 86a is connected to the second port 86b and is disconnected from the third port 86c. When the second solenoid valve 86 is in the second position, the first port 86a is connected to the third port 86c and is disconnected from the second port 86b.

[0043] The first solenoid valve 84 and the second solenoid valve 86 are connected to the controller and are controlled to be turned on and off by a signal output from the controller. The position sensor 88 mounted on the sensor slot 24 of the cylinder body 12 detects the magnetic field of the magnet 48 mounted on the first rack 40 or the second rack 42. Since the first rack 40 and the second rack 42 move synchronously, the position sensor 88 can be configured to detect the magnetic field of either the magnet 48 of the first rack 40 or the magnet 48 of the second rack 42.

[0044] The position sensor 88 is connected to the controller, and a signal detected by the position sensor 88 is input to the controller. The signal detected by the position sensor 88 is a signal about the position (actual position) of the first rack 40 or the second rack 42. The position of the first rack 40 or the second rack 42 corresponds to the mutual spacing of the first finger 30 and the second finger 32.

[0045] The target position of the first rack 40 or the second rack 42 is inputted from the outside to the controller. The target position of the first rack 40 or the second rack 42 corresponds to the target interval between the first finger 30 and the second finger 32. In the following description, in order to avoid redundant expressions, the "actual position of the first rack 40 or the second rack 42" is sometimes referred to as the "actual position of the first rack 40".

[0046] The air chuck 10 according to the embodiment of the present invention is basically constructed as described above, and its function will be described below. The air chuck 10 mounted on the top of the robot arm is in a standby state, and the first electromagnetic valve 84 and the second electromagnetic valve 86 are both in an off state as an initial state (refer to Fig. 9 ).

[0047] In the initial state, the air in the first air chamber 60a and the fourth air chamber 60d is opened to the atmosphere through the first air passage 26a of the cylinder 12, the first air passage 68a of the first plate 68, the first electromagnetic valve 84, the first exhaust passage 68e, and the first exhaust port 74. In addition, the air in the second air chamber 60b and the third air chamber 60c is opened to the atmosphere through the second air passage 26b of the cylinder 12, the second air passage 68b of the first plate 68, the second electromagnetic valve 86, the second exhaust passage 68f, and the second exhaust port 76. Therefore, no driving force is generated to move the first finger 30 and the second finger 32 in the X direction.

[0048] In order to grasp and convey a plurality of workpieces densely placed on the ground one by one, an operation command is issued from the outside to the air chuck 10. The target position of the first rack 40 corresponding to the arrangement state (setting interval) of the workpiece is input in advance to the controller. The controller controls the first electromagnetic valve 84 and the second electromagnetic valve 86 to turn on and off so that the actual position of the first rack 40 detected by the position sensor 88 becomes the target position.

[0049] Specifically, when the actual position of the first rack 40 is closer to the first end cap 18a than the target position, and the mutual interval between the first finger 30 and the second finger 32 is shorter than the specified value, the first solenoid valve 84 is turned on and the second solenoid valve 86 is turned off. As a result, air is supplied to the first air chamber 60a and the fourth air chamber 60d, and the air in the second air chamber 60b and the third air chamber 60c is exhausted. The first finger 30 and the second finger 32 are driven in a direction away from each other (refer to Fig.10 The moving speeds of the first finger 30 and the second finger 32 can be adjusted by changing the opening of the second variable throttle valve 76 a attached to the second exhaust port 76 .

[0050] On the other hand, when the actual position of the first rack 40 is closer to the second end cap 18b than the target position and the mutual interval between the first finger 30 and the second finger 32 is longer than the specified value, the first solenoid valve 84 is turned off and the second solenoid valve 86 is turned on. As a result, air is supplied to the second air chamber 60b and the third air chamber 60c, and the air in the first air chamber 60a and the fourth air chamber 60d is exhausted. The first finger 30 and the second finger 32 are driven in a direction to approach each other (refer to Fig.11 The moving speeds of the first finger 30 and the second finger 32 can be adjusted by changing the opening of the first variable throttle valve 74 a attached to the first exhaust port 74 .

[0051] When the actual position of the first rack 40 reaches the target position, both the first solenoid valve 84 and the second solenoid valve 86 are turned on (refer to Fig.12 ). The air in the first air chamber 60a and the fourth air chamber 60d does not flow toward the first exhaust port 74, and does not flow toward the supply port 72 due to the action of the first check valve 78. Similarly, the air in the second air chamber 60b and the third air chamber 60c does not flow toward the second exhaust port 76, and does not flow toward the supply port 72 due to the action of the second check valve 80. That is, the air in the first air chamber 60a to the fourth air chamber 60d is in a closed state, and the movement of the first rack 40 and the second rack 42 stops.

[0052] At this time, the air pressure of the first air chamber 60a is equal to the air pressure of the second air chamber 60b, and the pressure-bearing area of ​​the first piston 52 is equal to the pressure-bearing area of ​​the second piston 54. Therefore, the force applied to the first rack 40 in the X2 direction by the air pressure of the first air chamber 60a is balanced with the force applied to the first rack 40 in the X1 direction by the air pressure of the second air chamber 60b. Similarly, the air pressure of the fourth air chamber 60d is equal to the air pressure of the third air chamber 60c, and the pressure-bearing area of ​​the fourth piston 58 is equal to the pressure-bearing area of ​​the third piston 56. Therefore, the force applied to the second rack 42 in the X1 direction by the air pressure of the fourth air chamber 60d is balanced with the force applied to the second rack 42 in the X2 direction by the air pressure of the third air chamber 60c.

[0053] Through the above actions, the first rack 40 and the second rack 42 are stably maintained at the target position. That is, the mutual interval between the first finger 30 and the second finger 32 is maintained at a specified value corresponding to the setting interval of the workpiece. Then, the robot arm (not shown) is driven, and the air chuck 10 approaches the workpiece to be gripped. At this time, since the mutual interval between the first finger 30 and the second finger 32 is maintained at a specified value, the accessories mounted on the first finger 30 and the second finger 32 do not contact the workpiece adjacent to the workpiece to be gripped.

[0054] After the air chuck 10 moves to a position where it can hold the workpiece, the second solenoid valve 86 remains on and the first solenoid valve 84 is turned off. The first finger 30 and the second finger 32 are driven in a direction approaching each other, and the workpiece is held by the accessories mounted on the first finger 30 and the second finger 32. Then, the robot arm is driven again, and the air chuck 10 holding the workpiece moves to a predetermined location.

[0055] So far, it has been explained that the air in the first air chamber 60a to the fourth air chamber 60d is sealed when the first solenoid valve 84 and the second solenoid valve 86 are turned on. Strictly speaking, even when the first solenoid valve 84 and the second solenoid valve 86 are turned on, the air in the first air chamber 60a to the fourth air chamber 60d is not completely sealed in the following case.

[0056] When the piston liner 52a or the piston liner 58a leaks, the air in the first air chamber 60a and the fourth air chamber 60d is not completely sealed. When the piston liner 54a or the piston liner 56a leaks, the air in the second air chamber 60b and the third air chamber 60c is not completely sealed. The same is true when the gaskets 62a to 62d and 64a to 64d leak.

[0057] In any of the above cases, the first rack 40 and the second rack 42 are stably held at the target positions by the first check valve 78 and the second check valve 80. That is, the mutual interval between the first finger 30 and the second finger 32 is maintained at a predetermined value.

[0058] For example, when air leakage occurs in the piston liner 52a or the piston liner 58a, the air in the first air chamber 60a or the fourth air chamber 60d leaks to the outside. However, the air from the air supply source 50 is immediately replenished to the first air chamber 60a or the fourth air chamber 60d by the action of the first check valve 78. Therefore, the pressure of the first air chamber 60a and the fourth air chamber 60d does not decrease, and the first rack 40 and the second rack 42 are stably maintained at the target position.

[0059] When air leakage occurs in the piston liner 54a or the piston liner 56a, the air in the second air chamber 60b or the third air chamber 60c leaks to the outside. However, the air from the air supply source 50 is immediately replenished to the second air chamber 60b or the third air chamber 60c by the action of the second check valve 80. Therefore, the pressure of the second air chamber 60b and the third air chamber 60c does not decrease, and the first rack 40 and the second rack 42 are stably maintained at the target position.

[0060] When the first electromagnetic valve 84 and the second electromagnetic valve 86 are turned on, the air in the first air chamber 60a to the fourth air chamber 60d may not be completely sealed if air that moves integrally with the air in the first air chamber 60a to the fourth air chamber 60d is included.

[0061] When the first electromagnetic valve 84 is turned on, the air in the first air passage 26a of the cylinder 12, the first air passage 68a of the first plate 68, and the first supply passage 68c, and the air in the first air chamber 60a and the fourth air chamber 60d operate in unison. When the second electromagnetic valve 86 is turned on, the air in the second air passage 26b of the cylinder 12, the second air passage 68b of the first plate 68, and the second supply passage 68d, and the air in the second air chamber 60b and the third air chamber 60c operate in unison.

[0062] When air leakage occurs in the first electromagnetic valve 84, air in the first air passage 68a and the first supply passage 68c of the first plate 68 leaks to the outside. When air leakage occurs in the second electromagnetic valve 86, air in the second air passage 68b and the second supply passage 68d of the first plate 68 leaks to the outside. In either case, the first rack 40 and the second rack 42 are stably held at the target position by the action of the first check valve 78 and the second check valve 80. That is, the mutual interval between the first finger 30 and the second finger 32 is maintained at a predetermined value.

[0063] When air leakage occurs in the first solenoid valve 84, air from the air supply source 50 is immediately replenished to the first air passage 68a and the first supply passage 68c of the first plate 68 by the action of the first check valve 78. Therefore, the pressure of the first air chamber 60a and the fourth air chamber 60d does not decrease, and the first rack 40 and the second rack 42 are stably maintained at the target position. When air leakage occurs in the second solenoid valve 86, air from the air supply source 50 is immediately replenished to the second air passage 68b and the second supply passage 68d of the first plate 68 by the action of the second check valve 80. Therefore, the pressure of the second air chamber 60b and the third air chamber 60c does not decrease, and the first rack 40 and the second rack 42 are stably maintained at the target position.

[0064] Since the air chuck 10 according to the present embodiment includes the first check valve 78 and the second check valve 80 , air can be immediately replenished even if air leakage occurs in a predetermined operating state, and the mutual interval between the first finger 30 and the second finger 32 is maintained at a predetermined value.

[0065] Furthermore, since the first to fourth air chambers 60a to 60d are arranged in the cylinder 12 and the first and second electromagnetic valves 84 and 86 are mounted on the first plate 68 constituting the valve body 66, the air circuit required for the intermediate stop can be arranged compactly.

[0066] In particular, the total length of the first air passage 26a of the cylinder 12, the first air passage 68a of the first plate 68, and the first supply passage 68c can be shortened as much as possible. That is, the total volume of these passages that move together with the air in the first air chamber 60a and the fourth air chamber 60d when the first solenoid valve 84 is turned on can be reduced as much as possible. Therefore, the change in the stop position of the first rack 40 and the second rack 42 caused by the compressibility of the air can be reduced as much as possible.

[0067] Similarly, the total length of the second air passage 26b of the cylinder 12, the second air passage 68b of the first plate 68, and the second supply passage 68d can be shortened as much as possible. That is, the total volume of these passages that move together with the air in the second air chamber 60b and the third air chamber 60c when the second solenoid valve 86 is turned on can be reduced as much as possible. Therefore, the change in the stop position of the first rack 40 and the second rack 42 caused by the compressibility of the air can be reduced as much as possible.

[0068] In this embodiment, the separation force air chamber is composed of two air chambers (first air chamber 60a and fourth air chamber 60d), and the approach force air chamber is composed of two air chambers (second air chamber 60b and third air chamber 60c). However, the separation force air chamber and the approach force air chamber may be composed of separate air chambers.

[0069] In addition, in the present embodiment, both the first finger 30 and the second finger 32 are supported to be able to slide, but it is also possible that one of the first finger 30 and the second finger 32 is fixed to the cylinder 12, and only the other is supported to be able to slide. The "forces are applied to the plurality of finger portions in directions of separation from each other" and "forces are applied to the plurality of finger portions in directions of approaching each other" mentioned in the present invention are based on the premise of including such a mode. In this case, the separation force air chamber and the approach force air chamber are also respectively constituted by separate air chambers.

[0070] In the present embodiment, the finger portion for gripping the workpiece is composed of the first finger portion 30 and the second finger portion 32. However, the finger portion may be composed of three or more finger portions arranged radially.

[0071] In addition, in the present embodiment, the air chuck 10 is described as including the solenoid valve control unit including the controller, but an external device such as a PLC may also serve as the controller.

[0072] The air chuck according to the present invention is not limited to the above-described embodiment, and various structures can be adopted without departing from the gist of the present invention.

Claims

1. An air chuck comprising a cylinder (12), a valve body (66) and a plurality of finger-shaped parts (30, 32), characterized in that: The invention is provided with a separation force air chamber (60a, 60d), an approach force air chamber (60b, 60c), a first solenoid valve (84), a second solenoid valve (86) and a sensor (88), wherein the separation force air chamber applies force to the plurality of finger-like parts in a direction of separation, and the approach force air chamber applies force to the plurality of finger-like parts in a direction of approaching each other, the first solenoid valve supplies and exhausts air in the separation force air chamber, and the second solenoid valve supplies and exhausts air in the approach force air chamber, the sensor detects the mutual intervals between the plurality of finger-like parts, and the first solenoid valve and the second solenoid valve are controlled so that the mutual intervals between the plurality of finger-like parts detected by the sensor become target intervals, The separation force air chamber and the approach force air chamber are arranged on the cylinder body, the first solenoid valve and the second solenoid valve are installed on the valve body, and a first check valve (78) is arranged in the middle of the flow path connecting the first solenoid valve and the supply port (72) of the valve body, and a second check valve (80) is arranged in the middle of the flow path connecting the second solenoid valve and the supply port.

2. The air chuck according to claim 1, characterized in that The first solenoid valve comprises a first port (84a), a second port (84b) and a third port (84c), wherein the first port is connected to the separation force air chamber, the second port is connected to the supply port, and the third port is connected to the first exhaust port (74); the second solenoid valve comprises a first port (86a), a second port (86b) and a third port (86c), wherein the first port is connected to the approach force air chamber, the second port is connected to the supply port, and the third port is connected to the second exhaust port (76).

3. The air chuck according to claim 2, characterized in that: The valve body is composed of a first plate (68) and a second plate (70), the first plate having the first exhaust port and the second exhaust port, and the second plate having the supply port.

4. The air chuck according to claim 3, characterized in that The second port of the first solenoid valve is connected to the supply port via a first supply passage (68c) formed on the first plate and a first supply passage (70a) formed on the second plate, and the second port of the second solenoid valve is connected to the supply port via a second supply passage (68d) formed on the first plate and a second supply passage (70b) formed on the second plate, the first check valve is arranged at an end of the first supply passage of the first plate, and the end is connected to the first supply passage of the second plate, and the second check valve is arranged at an end of the second supply passage of the first plate, and the end is connected to the second supply passage of the second plate.

5. The air chuck according to claim 1, characterized in that The cylinder body has a first cylinder hole (14) and a second cylinder hole (16), a first rack (40) is arranged in the first cylinder hole, a second rack (42) is arranged in the second cylinder hole, a first piston (52) is connected to one end of the first rack, a second piston (54) is connected to the other end of the first rack, a third piston (56) is connected to one end of the second rack, and a fourth piston (58) is connected to the other end of the second rack, the separation force air chamber is composed of a first air chamber (60a) divided by the first piston and a fourth air chamber (60d) divided by the fourth piston, the approach force air chamber is composed of a second air chamber (60b) divided by the second piston and a third air chamber (60c) divided by the third piston, and the air chuck has a pinion (38) meshing with the first rack and the second rack.

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