Clamp holder

Abstract

A finger (14) of a gripper has a claw (16), a first contact pad (18), and a second contact pad (20). The first contact pad (18) is attached to the claw part (16). The first contact pad (18) is solid. The second contact pad (20) is attached to the claw portion (16). The second contact pad (20) is located on the root side of the first contact pad (18). The second contact pad (20) has a buffer section (24), a cover section (26), and a shell section (28). The buffer section (24) has a base section (30) and a plurality of protrusions (32). Each of the protrusions (32) rises from the base (30).

Description

Technical Field

[0001] This specification discloses a gripper suitable for robots and the like. Background Technology

[0002] Industrial robots are used in tasks such as handling and assembling items. A typical robot has an arm and a gripper (also called an end effector) mounted on that arm. Grippers that attract items using magnetic or attractive forces are known. Grippers with finger-like parts for grasping items are also known.

[0003] Japanese Patent Application Publication No. 07-276281 discloses a gripper having finger-shaped parts including leaf springs and cushioning parts. In this gripper, the finger-shaped parts are moved by an actuator.

[0004] Japanese Patent Application Publication No. 2023-093789 discloses a gripper having finger-like portions including an elastic member. This elastic member has multiple hollow protrusions. The finger-like portions with these protrusions can gently grip the workpiece.

[0005] Existing technical documents: Patent documents: Patent Document 1: Japanese Patent Application Publication No. 07-276281; Patent document 2: Japanese Patent Application Publication No. 2023-093789. Summary of the Invention

[0006] The problem the invention aims to solve: A robot may sometimes handle soft or fragile items such as an egg and hard items such as the container used to hold that egg. It's possible that the gripping fingers suitable for one type of item may not be suitable for the other.

[0007] The applicant's intention is to provide a gripper suitable for handling a variety of articles with different characteristics.

[0008] Solution methods: The gripper disclosed in this specification has a finger-like portion with structures for approaching and moving away from an object. The finger-like portion has a claw portion, a first contact pad mounted on the claw portion, and a second contact pad mounted on the claw portion. The second contact pad has a buffer portion and a cover portion covering the buffer portion. The buffer portion includes a base and a protrusion rising from the base.

[0009] Invention effects: In this gripper, the first contact pad facilitates the accurate movement of objects. Furthermore, the second contact pad gently grips other objects. This gripper is suitable for handling a variety of items with different characteristics. Attached Figure Description

[0010] Figure 1 A front view of an industrial robot having a gripper according to one embodiment is shown schematically. Figure 2 To show Figure 1 An enlarged view of the gripper of the robot; Figure 3 middle, Figure 3 A is shown Figure 2 A cross-sectional view of the finger-like portion of the gripper. Figure 3 B is along Figure 3 A sectional view of line BB of A. Figure 3 C is along Figure 3 A cross-sectional view of line CC of A; Figure 4 for Figure 2 An enlarged cross-sectional view of a portion of the clamping device together with the first object; Figure 5 for Figure 2 An enlarged cross-sectional view of a portion of the clamping device together with a second object; Figure 6 middle, Figure 6 A is Figure 3 A cross-sectional view showing the finger-like portion of C together with the object. Figure 6 B is Figure 6 A cross-sectional view showing the finger-like part of A together with the object; Figure 7 A cross-sectional view showing a portion of the finger portion of the gripper according to other embodiments; Figure 8 middle, Figure 8 A is a cross-sectional view showing a portion of the finger portion of the gripper according to other embodiments. Figure 8 B is along Figure 8 A cross-sectional view of line BB of A; Figure 9 A perspective view is provided to further illustrate the buffer portion of the clamp according to other embodiments. Detailed Implementation

[0011] Hereinafter, preferred embodiments will be described in detail with appropriate reference to the accompanying drawings. The structure of one embodiment can be arbitrarily combined with the structures of other embodiments.

[0012] Figure 1 The industrial robot 2 shown has an arm 4 and a gripper 6. The gripper 6 is mounted on the arm 4. In the robot 2, a multi-joint arm, a parallel movement arm, etc., can be used. Figure 1 The image also shows object 8.

[0013] Figure 2 A gripper 6 is shown. This gripper 6 has a drive unit 10, a left slider 12a, a right slider 12b, a left finger portion 14a, and a right finger portion 14b. The drive unit 10 has a power device (not shown). As an example of a power device, a motor can be cited. Other examples of a power device include a pressure cylinder. The drive unit 10 may also have a power transmission mechanism, a reduction gear structure, etc. In this embodiment, the drive unit 10 has a motor and a ball screw.

[0014] Each slider 12 is mounted on the drive unit 10. The slider 12 is moved by the drive unit 10. The direction of movement of the slider 12 is the X direction. The slider 12 can be attached to and detached from the drive unit 10.

[0015] Each finger-shaped portion 14 is mounted on the slider 12. The finger-shaped portion 14 moves as the slider 12 moves. The direction of movement of the finger-shaped portion 14 is the X direction. The finger-shaped portion 14 can move towards the object 8 and can move away from the object 8. Through the movement of the two finger-shaped portions 14, the object 8 can be gripped by the gripper 6. Alternatively, the finger-shaped portions 14 can grip the object 8 by rotation rather than movement. In this embodiment, the right finger-shaped portion 14b has a shape that is flipped over from the left finger-shaped portion 14a. The number of finger-shaped portions 14 can be one or more. In this specification, the term "finger-shaped portion" refers to an object having a structure capable of gripping an object.

[0016] Figure 3 The image shows a finger-like portion 14. This finger-like portion 14 has a claw portion 16, a first contact pad 18, and a second contact pad 20. Alternatively, the finger-like portion 14 may have three or more contact pads.

[0017] Claw 16 hangs down from slider 12 (see also) Figure 2 The rigidity of the claw portion 16 is greater than that of the first contact pad 18 and greater than that of the second contact pad 20. Typically, the claw portion 16 is made of metal or hard resin. The claw portion 16 can be obtained by known methods. In this specification, the term "claw portion" refers to an object that can form the core of a finger-like part.

[0018] The first contact pad 18 is mounted on the claw portion 16. The first contact pad 18 is located on the tip side of the claw portion 16. Figure 3(Lower side of A). In this embodiment, the first contact pad 18 is solid. The material of the first contact pad 18 may be, for example, rubber or an elastomer. The first contact pad 18 is softer than the claw portion 16. The first contact pad 18 has better deformability than the claw portion 16. The first contact pad 18 has a face 22. The first contact pad 18 may also have protrusions, grooves, raised strips, textures, etc., on the face 22. The first contact pad 18 has a single-layer structure. The first contact pad 18 may also have two or more layers. The first contact pad 18 can be obtained by injection molding, stamping, etc.

[0019] The second contact pad 20 is mounted on the claw portion 16. The second contact pad 20 is located at the root side of the claw portion 16 relative to the first contact pad 18. Figure 3 (A, upper side). The second contact pad 20 has a cushion 24, a cover 26, and a shell 28. Alternatively, the first contact pad 18 may be located at the root side of the claw 16, and the second contact pad 20 may be located at the tip side of the claw 16.

[0020] The buffer portion 24 has a base 30 and a plurality of protrusions 32. In this embodiment, these protrusions 32 are arranged in a longitudinal and transverse pattern. Each protrusion 32 stands upright from the base 30. The direction of this uprighting is... Figure 3 To the right in A. Protrusion 32 has a cylindrical shape. Alternatively, protrusion 32 can have a prism shape. Alternatively, protrusion 32 can have a hemispherical shape.

[0021] In this embodiment, the protrusion 32 is hollow. In this embodiment, the protrusion 32 is located on its bottom side ( Figure 3 The left end of C has an opening 34. Therefore, air inside the protrusion 32 can be discharged to the outside through this opening 34. In addition, outside air can flow into the interior of the protrusion 32 through this opening 34.

[0022] The material used for the cushioning part 24 may include, for example, rubber or an elastomer. The cushioning part 24 is soft. The preferred hardness of the cushioning part 24 is 50 to 85. This hardness is measured using a type A durometer according to JIS K6253. The cushioning part 24 can be formed by injection molding, vacuum forming, stamping, or other methods.

[0023] Cover 26 covers cushion 24. Cover 26 abuts against the tip of protrusion 32. Cover 26 may also be bonded to cushion 24 by adhesive. Alternatively, cover 26 may be bonded to cushion 24 by bonding or welding. Cover 26 may also be integrally formed with cushion 24.

[0024] The cover portion 26 has a face portion 36. In this embodiment, the face portion 36 is flat. Alternatively, the second contact pad 20 may have a curved face portion 36. The cover portion 26 may also have protrusions, grooves, holes, raised strips, etc., on the face portion 36. The cover portion 26 may also have a pattern on the face portion 36. Examples of patterns include checkering, dot pattern, pear skin, wrinkles, and textures. Alternatively, a large number of particles may be dispersed on the cover portion 26, with some of these particles exposed on the face portion 36, thereby making the face portion 36 rough. Examples of particles include silica and rubber powder.

[0025] The material of the cover portion 26 may include thermosetting polymers such as silicone rubber, acrylonitrile-butadiene copolymer, and polyurethane; and thermoplastic polymers such as olefin elastomers and styrene elastomers. Alternatively, the cover portion 26 may contain additives such as fillers. The cover portion 26 is soft. The preferred hardness of the cover portion 26 is 30 to 80. This hardness is measured using a type A hardness tester according to JIS K6253.

[0026] The portion of the cover 26 that abuts against the protrusion 32 is called the "abutting portion," and the portion of the cover 26 other than the abutting portion is called the "non-abutting portion." The second contact pad 20 has multiple abutting portions and one non-abutting portion. Figure 3 As can be seen from B, multiple contact points are distributed within the matrix of non-contact portions. In this second contact pad 20, sufficient stress relative to compression is generated at the contact points. Furthermore, in this second contact pad 20, the non-contact portions contribute to flexibility.

[0027] The shell portion 28 has a pair of sidewalls 38, a bottom wall 40, a rear wall 42, and a partition wall 44. Figure 3 As shown in Figure A, the rear wall 42 and the partition wall 44 clamp the claw portion 16. In this embodiment, the shell portion 28 and the cover portion 26 are integral. Therefore, the material of the shell portion 28 is the same as the material of the cover portion 26. The cover portion 26, the side wall 38, the bottom wall 40, and the partition wall 44 cover the buffer portion 24.

[0028] Alternatively, the shell portion 28 can be fixed to the claw portion 16. Fixing methods include screws, adhesives, glues, and tape.

[0029] The cover 26 and the shell 28 can be obtained by injection molding, injection molding, etc.

[0030] Since the first contact pad 18 is solid and the second contact pad 20 has a buffer portion 24, the rigidity of the first contact pad 18 is greater than that of the second contact pad 20. When pushed in the X direction, the compression deformation rate of the second contact pad 20 is greater than that of the first contact pad 18.

[0031] The following describes an example of a method for manufacturing the finger portion 14. In this method, a first contact pad 18 is first joined to the claw portion 16. Next, the vicinity of the tip of the claw portion 16 is pressed between the rear wall 42 and the partition wall 44. Then, a second contact pad 20 is fixed to the claw portion 16 to obtain the finger portion 14.

[0032] Figure 4 The container 46 (the first object) is shown together with the clamp 6. The container 46 is relatively rigid. Figure 4 In the gripper 6, container 46 is held by the first contact pad 18 of the left finger-shaped portion 14a and the first contact pad 18 of the right finger-shaped portion 14b. As mentioned earlier, the first contact pad 18 has high rigidity. Therefore, container 46 is held in the correct posture by the gripper 6. Container 46 is transported by robot 2 to the work area and accurately placed in the designated position. Various objects other than container 46 that require accurate handling can be transported while being held by the two first contact pads 18.

[0033] Figure 5 Egg 48 (the second object) is shown together with the clamp 6. This egg 48 is more prone to breakage than the container 46. Figure 5 In this gripper 6, egg 48 is held by the second contact pad 20 of the left finger-like portion 14a and the second contact pad 20 of the right finger-like portion 14b. Specifically, egg 48 is held by a pair of cover portions 26. As mentioned earlier, the second contact pad 20 is easily deformable. Therefore, egg 48 is held by gripper 6 without breaking. Egg 48 is transported by robot 2 to the work area and placed in container 46. Eggs 48 vary in size. Compared to transporting smaller eggs 48, the second contact pad 20 deforms more when transporting larger eggs 48. Gripper 6 can transport egg 48 regardless of its size and shape. Various objects 8 other than eggs 48, whose size or shape is not fixed, can be transported while being held by two second contact pads 20. Objects with shapes such as cylinders, prisms, cones, pyramids, polyhedra, spheres, ellipses, etc., can be transported while being held by second contact pads 20.

[0034] After the egg 48 is placed in the container 46, the container 46 and the egg 48 are transported using the gripper 6. At this time, the edge of the container 46 is gripped by two second contact pads 20. Due to the high rigidity of each first contact pad 18, the gripper 6 can accurately transport even a large object 8.

[0035] The robot 2 can handle a variety of objects 8 with different characteristics. Therefore, there is no need to change the gripper 6 according to the object 8. In addition, there is no need to prepare multiple robots 2 for each object 8.

[0036] The first contact pad 18 is located on the tip side of the claw portion 16, closer to the second contact pad 20 (in this embodiment, it is on the lower side in the direction of the plumb bob). Figure 5 In the deformed state of the second contact pad 20, the second contact pad 20 grips the egg 48 (object 8). Even when a force (gravity) is applied to the object 8 towards the tip, the first contact pad 18, being highly rigid, inhibits the object 8 from moving towards the tip. The gripper 6 can accurately grip the object 8. From the viewpoint of inhibiting the movement of the object 8, it is preferable that the second contact pad 20 is mounted on the claw portion 16 with no gap between it and the first contact pad 18.

[0037] Because the first contact pad 18 is located on the tip side of the second contact pad 20, even though the second contact pad 20 is thicker, it will not prevent the first contact pad 18 from gripping the object 8. The thicker second contact pad 20 has excellent deformability.

[0038] Figure 6 Figure A shows the second contact pad 20 and the object 8. Figure 6 In A, object 8 is moved away from the second contact pad 20. Through the second contact pad 20... Figure 6 The arrow A1 in A moves in the direction of the object, causing the second contact pad 20 to come into contact with the object 8. After contact, the second contact pad 20... Figure 6 As shown in B. In Figure 6 In section B, the cover 26 is curved. A portion of the cover 26 extends between two protrusions 32. Each protrusion 32 inhibits the movement of the object 8 in the Z direction.

[0039] As mentioned earlier, because the protrusion 32 is hollow, it has excellent deformability. When the protrusion 32 is subjected to a force from the object 8, it deforms according to the shape of the object 8. The deformed protrusion 32 is as follows: Figure 6 As shown in B. This deformation inhibits the collapse of the protrusion 32. The protrusion 32 can inhibit the movement of the object 8 in the Z direction.

[0040] Figure 7 The image shows a portion of the finger-like portion 50 of a gripper according to other embodiments. This finger-like portion 50 has a claw portion 52, a first contact pad 54, and a second contact pad 56. The claw portion 52 has a... Figure 3 The claw portion 16 shown has the same structure.

[0041] The first contact pad 54 is mounted on the claw portion 52. The first contact pad 54 is located on the tip side of the claw portion 52. In this embodiment, the first contact pad 54 is solid. The material of the first contact pad 54 is similar to... Figure 3 The first contact pad 18 shown is made of the same material.

[0042] The second contact pad 56 is mounted on the claw portion 52. The second contact pad 56 is located on the root side of the claw portion 52. The second contact pad 56 has a buffer portion 58, a cover portion 60, and a shell portion 62.

[0043] The buffer portion 58 has a base 64 and multiple protrusions 66. Each protrusion 66 is solid. The protrusion 66 may also be hollow. The material of the buffer portion 58 is similar to... Figure 3 The buffer section 24 shown is made of the same material.

[0044] The cover 60 covers the cushioning portion 58. The cover 60 abuts against the protrusion 66. The material of the cover 60 is similar to... Figure 3 The material of the cover 26 shown is the same.

[0045] Shell portion 62 has a rear wall 68 and a partition wall 70. Although not shown, shell portion 62 has... Figure 3 The shell portion 28 shown has the same sidewalls. The rear wall 68 and the partition wall 70 clamp the claw portion 52. In this embodiment, the shell portion 62 and the cover portion 60 are integral. Therefore, the material of the shell portion 62 is the same as that of the cover portion 60. The partition wall 70 and the cover portion 60 clamp the buffer portion 58. The rear wall 68 extends towards... Figure 7 The lower part of the shell 62 extends to cover the tip 72 of the claw portion 52. The rear wall 68 inhibits the shell portion 62 from peeling off from the claw portion 52.

[0046] In this embodiment, the cover portion 60 is integral with the first contact pad 54. Therefore, the shell portion 62 is also integral with the first contact pad 54. The material of the cover portion 60 is the same as the material of the first contact pad 54. The material of the shell portion 62 is also the same as the material of the first contact pad 54.

[0047] Because the first contact pad 54 is solid and the second contact pad 56 has a buffer portion 58, the rigidity of the first contact pad 54 is greater than that of the second contact pad 56. When pushed in the X direction, the compression deformation rate of the second contact pad 56 is greater than that of the first contact pad 54. Objects requiring precise handling can be handled while being clamped by both first contact pads 54. Objects with variable sizes or shapes can be handled while being clamped by both second contact pads 56.

[0048] Since the cover 60 and the first contact pad 54 are integral, the first contact pad 54 constrains the cover 60. The cover 60 moves towards... Figure 7 The vertical movement of the paper surface is suppressed by the first contact pad 54. Therefore, the object is prevented from falling off in this gripper.

[0049] Since the cover 60 is integrated with the first contact pad 54, the clamp is easy to manufacture.

[0050] Figure 8The image further illustrates a portion of the finger-like portion 74 of a gripper according to other embodiments. This finger-like portion 74 has a claw portion 76, a first contact pad 78, and a second contact pad 80. The claw portion 76 has a... Figure 3 The claw portion 16 shown has the same structure.

[0051] The first contact pad 78 is mounted on the claw portion 76. The first contact pad 78 is located on the tip side of the claw portion 76. In this embodiment, the first contact pad 78 is solid. The material of the first contact pad 78 is similar to... Figure 3 The first contact pad 18 shown is made of the same material. The first contact pad 78 has a main portion 82 and a pair of raised portions 84. The main portion 82 extends along the Z direction. Each raised portion 84 rises from the main portion 82 and extends along the Y direction. The first contact pad 78 surrounds the second contact pad 80 in three directions. Alternatively, the first contact pad 78 may surround the second contact pad 80 in four directions.

[0052] The second contact pad 80 is mounted on the claw portion 76. The second contact pad 80 is located at the root side of the claw portion 76. The second contact pad 80 has a buffer portion 86, a cover portion 88, and a shell portion 90. The buffer portion 86 has a... Figure 3 The structure of the buffer portion 24 shown is the same. The cover portion 88 has the same structure as... Figure 3 The structure of the cover 26 shown is the same. The shell 90 and the cover 88 are integrated.

[0053] Because the first contact pad 78 is solid and the second contact pad 80 has a buffer portion 86, the rigidity of the first contact pad 78 is greater than that of the second contact pad 80. When pushed in the X direction, the compression deformation rate of the second contact pad 80 is greater than that of the first contact pad 78. Objects to be transported can be transported while being held by both first contact pads 78. Objects with variable sizes or shapes can be transported while being held by both second contact pads 80. Objects requiring precise transport can be held by either two main portions 82 or by multiple upright portions 84.

[0054] Figure 9 The image further illustrates the buffer portion 92 of the gripper according to other embodiments. The structure of the gripper's components, excluding the buffer portion 92, is similar to... Figure 3The clamp 6 shown has the same structure. The buffer portion 92 has a base 94 and a plurality of protrusions 96. Each protrusion 96 has a root 98 and a tip 100. In this embodiment, the root 98 has a cylindrical shape. The root 98 stands upright from the base 94. In this embodiment, the tip 100 has a cylindrical shape. The tip 100 stands upright from the root 98. The diameter of the tip 100 is smaller than the diameter of the root 98. The protrusions 96 can contribute to the flexibility and holding force of the buffer portion 92. The protrusions 96 can be solid or hollow. The protrusions 96 can also have a structure where the root 98 is hollow and the tip 100 is solid.

[0055] [Public Projects] Preferred implementation methods are disclosed in the following items.

[0056] [Project 1] A clamp, It has finger-like parts, which have structures that allow it to approach and move away from the object. The finger-like portion has: a claw portion, a first contact pad mounted on the claw portion, and a second contact pad mounted on the claw portion. The second contact pad has a cushioning portion and a cover portion that covers the cushioning portion. The buffer portion includes a base and a protrusion rising from the base.

[0057] [Project 2] According to the clamp described in Project 1, the first contact pad is solid.

[0058] [Project 3] According to the gripper of item 1 or 2, the first contact pad is located on the tip side of the claw portion, and the second contact pad is located on the root side of the claw portion.

[0059] [Project 4] According to any one of items 1 to 3, the cover is integral with the first contact pad.

[0060] [Project 5] According to any one of items 1 to 4, the protrusion is hollow.

[0061] [Project 6] A method for operating a robot, comprising: The process of preparing a gripper having a finger-like portion having a structure for approaching and moving away from an object, the finger-like portion having a claw portion, a first contact pad mounted on the claw portion and a second contact pad mounted on the claw portion, the second contact pad having a buffer portion and a cover portion covering the buffer portion, the buffer portion including a base portion and a protrusion rising from the base portion; The process of holding the first object with the clamp while bringing the first object into contact with the first contact pad; The process of separating the first contact pad from the first object; as well as The process of holding the second object with the clamp while bringing the second object into contact with the second contact pad.

[0062] [Project 7] A method for operating a robot, comprising: The process of preparing a gripper having a finger-like portion having a structure for approaching and moving away from an object, the finger-like portion having a claw portion, a first contact pad mounted on the claw portion and a second contact pad mounted on the claw portion, the second contact pad having a buffer portion and a cover portion covering the buffer portion, the buffer portion including a base portion and a protrusion rising from the base portion; The process of holding the second object with the clamp while bringing the second object into contact with the second contact pad; The process of separating the second object from the second contact pad; as well as The process of holding the first object with the clamp while bringing the first object into contact with the first contact pad.

[0063] Industrial applications: The gripper described above is suitable for industrial robots such as assembly robots, handling robots, and collaborative robots. It is also suitable for service robots, assistive robots, and nursing robots used in homes or hospitals. Furthermore, it is suitable for prostheses.

[0064] Symbol explanation: 6. Clamping device; 14. Finger-like part; 16···Claws; 18···First contact pad; 20···Second contact pad; 22···Face; 24. Buffer section; 26···Cover section; 28. Shell; 30···base; 32. A sudden bulge; 34···Opening; 36···Face; 38···Side wall; 40···Bottom wall; 42···Rear wall; 44··· Separator wall; 46··· Containers; 48... eggs; 50···finger-like part; 52···Claws; 54···First contact pad; 56···Second contact pad; 58··· Buffer section; 60···Cover section; 62···Shell; 64···base; 66...protrusion; 68...rear wall; 70··· Divider wall; 74···finger-like part; 76···Claws; 78···First contact pad; 80...Second contact pad; 82···Main Department; 84···Erecting section; 86··· Buffer section; 88···Cover section; 90···Shell section; 92··· Buffer section; 94···base; 96...protrusion; 98··· Roots; 100···Tip.

Claims

1. A clamp, characterized in that, It has finger-like parts, which have structures that allow it to approach and move away from the object. The finger-like portion has: a claw portion, a first contact pad mounted on the claw portion, and a second contact pad mounted on the claw portion. The second contact pad has a cushioning portion and a cover portion that covers the cushioning portion. The buffer portion includes a base and a protrusion rising from the base.

2. The clamp according to claim 1, characterized in that, The first contact pad is solid.

3. The clamp according to claim 1 or 2, characterized in that, The first contact pad is located on the tip side of the claw, and the second contact pad is located on the root side of the claw.

4. The clamp according to claim 1 or 2, characterized in that, The cover is integral with the first contact pad.

5. The clamp according to claim 1 or 2, characterized in that, The protrusion is hollow.

6. A method for operating a robot, characterized in that, have: The process of preparing a gripper having a finger-like portion having a structure for approaching and moving away from an object, the finger-like portion having a claw portion, a first contact pad mounted on the claw portion and a second contact pad mounted on the claw portion, the second contact pad having a buffer portion and a cover portion covering the buffer portion, the buffer portion including a base portion and a protrusion rising from the base portion; The process of holding the first object with the clamp while bringing the first object into contact with the first contact pad; The process of separating the first contact pad from the first object; as well as The process of holding the second object with the clamp while bringing the second object into contact with the second contact pad.

7. A method for operating a robot, characterized in that, have: The process of preparing a gripper having a finger-like portion having a structure for approaching and moving away from an object, the finger-like portion having a claw portion, a first contact pad mounted on the claw portion and a second contact pad mounted on the claw portion, the second contact pad having a buffer portion and a cover portion covering the buffer portion, the buffer portion including a base portion and a protrusion rising from the base portion; The process of holding the second object with the clamp while bringing the second object into contact with the second contact pad; The process of separating the second contact pad from the second object; as well as The process of holding the first object with the clamp while bringing the first object into contact with the first contact pad.

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