CN114474131A

CN114474131A - Clamping gripper

Info

Publication number: CN114474131A
Application number: CN202210108123.1A
Authority: CN
Inventors: 江励; 赖根; 汤健华
Original assignee: Wuyi University
Current assignee: Wuyi University
Priority date: 2022-01-28
Filing date: 2022-01-28
Publication date: 2022-05-13
Anticipated expiration: 2042-01-28
Also published as: CN114474131B

Abstract

The invention discloses a clamping gripper and relates to the field of manipulators. Wherein, the centre gripping tongs includes: a mounting seat; the guide rails are fixedly connected with the mounting seat; the clamping jaws comprise at least two sliding parts, connecting pieces and clamping assemblies, one end of each sliding part is connected with the corresponding guide rail in a sliding mode, and the other end of each sliding part is fixedly connected with the corresponding connecting piece; the clamping assembly comprises a plurality of cams and a plurality of rotating shafts, the rotating shafts are arranged at intervals along the length direction of the connecting piece, the cams are connected to the rotating shafts in a one-to-one corresponding rotating mode, the cams comprise abutting portions protruding out of the connecting piece in the clamping direction, and the distance from the end portions of the outer peripheral edges of the abutting portions to the rotating shafts is gradually increased along the upward direction; and the driving device is fixedly connected with the mounting seat or the guide rail. The part of the cam arranged on the clamping jaw, which protrudes out of the connecting piece, is abutted against the clamped object so as to limit the position of the clamped object. When the clamping force is too large, the cam can rotate towards the direction far away from the clamped object, and the situation that the clamped object is damaged due to too large clamping force can be reduced.

Description

Clamping gripper

Technical Field

The invention relates to the field of manipulators, in particular to a clamping gripper.

Background

In the production process of modern manufacturing industry, mechanical grippers are widely used in automatic production lines to replace people to carry out large-batch and high-quality transportation work. In the related art, there is a clamping jaw for clamping and carrying an object, and the clamping jaw includes a connecting seat and two clamping arms, and the two clamping arms are controlled to move toward or away from each other to clamp or release the object. However, such jaws typically grip an object with a rigid contact, and the gripping force is poorly controlled and can easily damage the object.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a clamping gripper which can reduce the damage of an object in the process of clamping the object.

A grip grab according to an embodiment of the present invention includes:

a mounting seat;

the guide rails are fixedly connected with the mounting seat;

the clamping jaws comprise sliding parts, connecting pieces and clamping assemblies, one ends of the sliding parts are connected with the guide rails in a sliding mode, and the other ends of the sliding parts are fixedly connected with the connecting pieces; the clamping assembly comprises a plurality of cams and a plurality of rotating shafts, the rotating shafts are arranged at intervals along the length direction of the connecting piece, the cams are connected to the rotating shafts in a one-to-one corresponding rotating mode, the cams comprise abutting portions protruding out of the connecting piece in the clamping direction, and the distance from the end portions of the peripheral edges of the abutting portions to the rotating shafts is gradually increased along the upward direction;

and the driving device is fixedly connected with the mounting seat or the guide rail and is used for driving at least two clamping jaws to mutually approach or depart from each other along the linear direction.

The clamping gripper according to the embodiment of the invention has at least the following beneficial effects:

during clamping, the driving device drives the at least two clamping jaws to approach each other along the extension direction of the guide rail so as to clamp the object. The abutting part of the cam abuts against the clamped object to limit the position of the clamped object. When the clamping force is too large, the cam can rotate towards the direction far away from the clamped object, and the situation that the clamped object is damaged due to the fact that the clamping force is too large is reduced. The clamped object has a downward falling tendency under the action of gravity, the cam can rotate towards the direction close to the clamped object under the action of friction force, and the distance from the end part of the outer peripheral edge of the abutting part to the rotating shaft is gradually increased, so that the cam can be self-locked to clamp the object. The cam has a plurality of objects that can adapt to the centre gripping difference, improves the commonality of centre gripping tongs and the stability of centre gripping.

According to some embodiments of the invention, the clamping jaw comprises a torsion spring, the torsion spring is sleeved on the rotating shaft, and the torsion spring is used for resetting the cam.

According to some embodiments of the invention, the connecting member is provided with a first limiting groove, the cam is provided with a second limiting groove, and the torsion spring comprises a first radial arm and a second radial arm, the first radial arm being provided in the first limiting groove, and the second radial arm being provided in the second limiting groove.

According to some embodiments of the invention, the outer circumference of the abutment is involute to the contour of the outer circumference of the abutment.

According to some embodiments of the invention, the part of the cam protruding from the connecting piece is provided with a plurality of grooves, the grooves are arranged at intervals along the periphery of the cam, the cam further comprises a skid-proof piece, one part of the skid-proof piece is fixedly connected with the grooves, and the other part of the skid-proof piece protrudes from the grooves towards the clamping direction.

According to some embodiments of the invention, the groove comprises a first clamping groove and a second clamping groove, the first clamping groove is communicated with the second clamping groove, and an included angle a is formed between a lower bottom surface of the first clamping groove and a lower bottom surface of the second clamping groove, and the included angle a is satisfied as 0 degrees < a <180 degrees.

According to some embodiments of the invention, the driving device comprises motors and lead screws, the number of the motors corresponds to the number of the clamping jaws, the motors are fixedly connected to the mounting bases, the output ends of the motors are fixedly connected to one ends of the lead screws, and the lead screws are in threaded connection with the sliding parts.

According to some embodiments of the invention, the connecting member comprises at least three connecting plates, the at least three connecting plates are arranged at intervals along the width direction of the guide rail, and the clamping assemblies are arranged in at least two groups and are respectively arranged between the adjacent connecting plates.

According to some embodiments of the invention, the cam portion extends outward to form a first limiting portion, the connecting member is provided with a first limiting member, the first limiting portion can abut against the first limiting member to limit a rotation angle of the cam in a first direction, the cam portion protrudes outward to form a second limiting portion, the connecting member is provided with a second limiting member, the second limiting portion can abut against the second limiting member to limit a rotation angle of the cam in a second direction, and the first direction is opposite to the second direction.

According to some embodiments of the invention, the mounting seat comprises a fastening piece, a guide piece and a moving piece, the moving piece is sleeved on the guide piece, the moving piece can move along the length direction of the guide piece to adjust the whole length of the mounting seat, the moving piece and the guide piece are both provided with a plurality of connecting holes along the length direction, and the fastening piece is arranged in the connecting holes in a penetrating manner to fix the relative position of the moving piece and the guide piece.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 is a schematic diagram of an overall configuration of a gripping finger according to one embodiment of the present invention;

FIG. 2 is an exploded view of a jaw provided in accordance with an embodiment of the present invention;

FIG. 3 is an enlarged schematic view at A in FIG. 2;

FIG. 4 is an exploded view of another perspective of a jaw provided in accordance with an embodiment of the present invention;

FIG. 5 is a schematic illustration of a cam provided in accordance with an embodiment of the present invention;

fig. 6 is a schematic structural view of a gripping hand provided in an embodiment of the present invention.

Reference numerals:

a gripping grip 1000;

the mounting seat 100, the moving member 110, the connecting hole 111, the guide member 120, and the fastening member 130;

guide rail 200, limit structure 210;

the clamping jaw comprises a clamping jaw 300, a sliding part 310, a nut 311, a connecting piece 320, a connecting plate 321, a first limiting groove 3211, a rotating shaft 322, a first limiting part 323, a second limiting part 324, a cam 330, a first limiting part 331, a second limiting part 332, a second limiting groove 333, a convex tooth 334, a butting part 335, a groove 336, a first clamping groove 3361, a second clamping groove 3362, a bearing 335, a torsion spring 340, a first rotating arm 341 and a second rotating arm 342;

drive 400, motor 410, lead screw 420.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If there is a description of first and second for the purpose of distinguishing technical features only, this is not to be understood as indicating or implying a relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

Referring to fig. 1 and 2, a gripping hand grip 1000 is provided in accordance with one embodiment of the present invention. The gripping tongs 1000 may be used in an automated manufacturing line to replace a human being to perform a large batch, high quality handling job. In some cases, the clamping grip 1000 may have a clamping force greater than the maximum pressure that the object can bear due to improper control or abnormal conditions, and the clamping grip 1000 of the present invention can reduce the damage to the object due to excessive clamping force, so as to better protect the object being handled.

Referring to fig. 1 and 2, the grip grab 1000 includes a mount 100, a rail 200, a jaw 300, and a driving device 400. The mounting seat 100 is provided with a mounting position, the mounting position is used for mounting the guide rail 200, so that the guide rail 200 is fixedly connected with the mounting position, and the mounting position can be a threaded hole or an area convenient for welding the guide rail 200. The mounting seat 100 is provided with a plurality of mounting positions, so that the number of the clamping jaws 300 and the guide rails 200 can be increased according to actual requirements to replace different clamping modes. For example, when there are three jaws 300, the gripping is more stable than the two modes, and a large round object can be gripped.

Referring to fig. 2, there are at least two jaws 300 such that at least two jaws 300 cooperate to grip an object. The clamping jaw 300 comprises a sliding member 310, a connecting member 320 and a clamping assembly, wherein one end of the sliding member 310 is slidably connected with the guide rail 200, and the other end of the sliding member 310 is fixedly connected with the connecting member 320 so as to drive the connecting member 320 to move along the guide rail 200. The clamping assembly comprises a plurality of cams 330 and a plurality of rotating shafts 322, the plurality of rotating shafts 322 are arranged at intervals along the length direction of the connecting piece 320, and the plurality of cams 330 are in one-to-one corresponding rotating connection with the rotating shafts 322. The cam 330 includes an abutting portion 335 protruding from the connecting member 320 in the clamping direction, and the abutting portion 335 abuts against the object in the process of clamping the object, so as to fix the position of the clamped object. In the upward direction, the distance from the end of the outer peripheral edge of the abutting portion to the rotating shaft gradually increases. The plurality of cams 330 may be adapted to grip different objects to improve the versatility and gripping stability of the gripping fingers 1000.

The gripping direction refers to a moving direction of the gripping jaw 300 when gripping an object. It should be noted that the rotating shaft 322 may be a bolt, or may be a structure formed by protruding the connecting member 320 outward. For example, in some embodiments, when the rotating shaft 322 of the cam 330 is a bolt and the connecting member 320 includes a plurality of connecting plates 321, the bolt may serve to connect the plurality of connecting plates 321 in addition to the rotating shaft 322 of the cam 330, so as to improve the utilization rate of the bolt.

Referring to fig. 1, the driving device 400 is disposed on a mounting position of the mounting base 100 and is fixedly connected to the mounting base 100. The driving device 400 is used to drive at least two clamping jaws 300 to approach or move away from each other to clamp or release an object. It should be noted that the driving device 400 may also be fixedly connected to the guide rail 200, and the invention is not limited in detail herein, and an appropriate scheme may be selected according to actual situations.

It can be understood that, in the process of clamping the object, the driving device 400 drives the clamping jaws 300 to approach each other, the abutting portion 335 of the cam 330 contacts the object to be clamped first, when the clamping force is gradually increased, the cam 330 rotates in the direction away from the clamped object, so as to achieve the buffering effect, and reduce the damage of the clamped object caused by the excessive clamping force. The clamped object tends to fall down, the cam 330 is rotated in a direction approaching the clamped object by the friction force, and the distance from the end of the outer peripheral edge of the abutting part 335 to the rotating shaft is gradually increased, so that the cam 330 can be self-locked to clamp the object.

In some embodiments, as described with reference to fig. 2, 3 and 5, the clamping jaw 300 further includes a torsion spring 340, the torsion spring 340 is sleeved on the rotating shaft 322, and the torsion spring 340 can achieve buffering and resetting of the cam 330. Reset refers to the position at which the torsion spring 340 drives the cam 330 to a position at which it does not clamp an object. It can be understood that when the clamping force is greater than the elastic force of the torsion spring 340 when clamping the object, the cam 330 can overcome the elastic force of the torsion spring 340 to rotate in the direction away from the clamped object, and the situation that the clamped object is damaged due to the excessive clamping force can be reduced. When the clamped object is released, the cam 330 can be returned to the position where the object is not clamped by the elastic force of the torsion spring 340.

In some embodiments, referring to fig. 3 and 5, the connecting member 320 is provided with a first limiting groove 3211, the cam 330 is provided with a second limiting groove 333, and the torsion spring 340 includes a first radial arm 341 and a second radial arm 342, the first radial arm 341 is disposed in the first limiting groove 3211, and the second radial arm 342 is disposed in the second limiting groove 333. The first and second limiting

grooves

3211 and 333 are used to limit the position of the torsion spring 340, prevent the torsion spring 340 from being disengaged, and improve the reliability of the clamping gripper 1000, and meanwhile, in the rotation process of the cam 330, the first spiral arm 341 can be elastically deformed by abutting against the wall surface of the first limiting groove 3211, and the second spiral arm 342 can be elastically deformed by abutting against the wall surface of the second limiting groove 333, so as to limit the position of the cam 330. It should be noted that, the position of the limiting torsion spring 340 may also be that the connecting member 320 and the cam 330 are both provided with a limiting protrusion, and both ends of the torsion spring 340 respectively abut against the limiting protrusions, and also can play a role in limiting the position of the torsion spring 340.

In some embodiments, referring to fig. 5, the cam 330 includes an abutting portion 335, the abutting portion 335 protrudes from the connecting member 320, and an outer circumference of the abutting portion 335 is involute to and extends upward along a contour line of the abutting portion 335. Wherein, the involute is the base circle involute of the rotation center of the cam 330. It will be appreciated that the peripheral edge of the abutment 335 being involute has the following beneficial effects:

since the cam 330 can rotate under the abutment of the clamped object, in order to ensure that the cam 330 can always partially abut against the clamped object in the rotation process, the outer peripheral edge of the abutting part 335 is arc-shaped, so that the side wall of all the parts can be kept to abut against the clamped object to limit the position of the clamped object, and the looseness of the clamped object is reduced.

The clamped object has a tendency of falling downwards in the clamping process, so that the force for rotating the cam 330 towards the direction close to the clamped object is given to the cam, and the distance from a point in the extending direction of the involute to the circle center is gradually increased, so that the clamped object has a tendency of falling, the cam 330 can rotate towards the direction close to the clamped object to clamp the clamped object, the clamped object is self-locked, and the risk of falling of the clamped object is reduced.

Because the normal line of any point on the involute is always tangent to the base circle, when the clamped object is in butt joint with the abutting part 335, a component force at the abutting part can be always tangent to the base circle, when the component force is larger, the cam 330 can be driven to rotate, the condition that the cam 330 cannot rotate due to the fact that resultant force passes through the center of a circle is avoided, and the condition that the clamped object is damaged can be reduced.

To reduce the risk of the object falling during the clamping of the object, an anti-slip structure needs to be provided on the cam 330. With continued reference to fig. 5, in some embodiments, the portion of the cam 330 projecting above the connector 320 includes a plurality of teeth 334, the plurality of teeth 334 being spaced apart along a circumference of the cam 330, and grooves 336 being formed between adjacent teeth 334. The cam 330 further includes a non-slip member (not shown) which is partially disposed in the groove 336 and partially protrudes from the groove 336 in the clamping direction. It will be appreciated that in some embodiments, the anti-slip member may be initially formed of liquid silicone or rubber, such as silicone, which is poured into the groove 336 formed by the adjacent tooth 334 to form the anti-slip member wrapped around the portion of the cam 330 after it has solidified. Thus, the groove 336 primarily functions as a fixed cleat. The anti-skidding piece is made of silica gel, the silica gel can increase the friction force between the cam 330 and the clamped object, and meanwhile, the silica gel is soft in property and elastic, can better protect the clamped object, and reduces the surface damage of the clamped object.

Referring to fig. 5, the recess 336 includes a first engaging groove 3361 and a second engaging groove 3362, the first engaging groove 3361 communicates with the second engaging groove 3362, and an angle a between a lower bottom surface of the first engaging groove 3361 and a lower bottom surface of the second engaging groove 3362 satisfies 0 ° < a <180 °. It can be understood that the first clamping groove 3361 and the second clamping groove 3362 form an included angle, so that the anti-falling effect can be further improved, and the falling-off of the anti-sliding part is reduced. In some embodiments, the width of the second engaging groove 3362 on the side away from the rotation center is smaller than the width of the second engaging groove 3362 on the side close to the rotation center, so as to further reduce the slip-off of the slip-preventing member.

Referring to fig. 6, in some embodiments, the drive 400 includes motors 410 and lead screws 420, each of the number of motors 410 and lead screws 420 being the same as the number of jaws 300. The motor 410 is fixedly connected to the mounting base 100, an output end of the motor 410 is fixedly connected to one end of the screw rod 420 to drive the screw rod 420 to rotate, the screw rod 420 is connected to the sliding member 310 through a thread, when the screw rod 420 rotates, the sliding member 310 can be driven to slide along the guide rail 200, the screw rod 420 is connected to the sliding member 310 through a thread, the rotating motion can be changed into linear motion, and the motor 410 is used for driving the clamping jaws 300 to approach or depart from each other. The screw 420 and the slider 310 may be directly threaded on the slider 310, or the slider 310 may include a nut 311, and the screw 420 and the nut 311 are threaded. It should also be noted that the motor 410 may be replaced by a hydraulic cylinder or an air cylinder, and a suitable scheme is selected according to actual situations.

It will be appreciated that the linear drive clamping of the jaws 300 is contemplated to allow for the lead screw 420 to be self-locking under certain circumstances. For example, the helix angle of the screw 420, which requires self-locking, should be less than the friction angle of the material of the screw pair, i.e., the tangent of the helix angle is less than the coefficient of friction. In the process of clamping and conveying the object, the clamping jaw 300 tends to be pushed open towards both sides by the clamped object, so that the self-locking screw rod limits the clamping jaw 300 to be pushed open, the driving pressure of the motor 410 is reduced, and the requirement on the motor 410 is further reduced.

Referring to fig. 1 and 2, in some embodiments, the connection member 320 includes at least three connection plates 321, the at least three connection plates 321 are spaced apart along the width direction of the guide rail 200, and at least two sets of clamping members are disposed between the adjacent connection plates 321. For example, the connecting member 320 includes three connecting plates 321, two sets of clamping members are provided, two gaps are formed when the three connecting plates 321 are spaced apart, and two sets of clamping members are respectively provided between the two gaps and connected to the connecting plates 321. It can be understood that the plurality of groups of clamping assemblies can improve the stability of clamping and reduce the loosening phenomenon of the clamped object.

Referring to fig. 2, 3 and 5, the cam 330 partially extends outward to form a first limiting portion 331, the connecting member 320 is provided with a first limiting member 323, and in the process of clamping the object, after the cam 330 is pressed by the object, the first limiting portion 331 can abut against the first limiting member 323 to limit the rotation angle of the cam 330 in the first direction, so as to prevent the cam 330 from rotating excessively. In other embodiments, the cam 330 partially protrudes outward to form a second limiting portion 332, the connecting member 320 is provided with a second limiting member 324, and after the object is released, the second limiting portion 332 can abut against the second limiting member 324 to limit the rotation angle of the cam 330 in the second direction, so as to improve the safety. It should be noted that, the first direction is opposite to the second direction, and the first limiting part 323 and the second limiting part 324 may be welded to the connecting part 320, or may be formed by bolts.

Referring to fig. 5, in some embodiments, the outer circumference of the first position-limiting portion 331 is a circular arc. It can be understood that the first position-limiting portion 331 can also abut against the clamped object when clamping some objects, so as to limit the position of the clamped object.

Referring to fig. 1, the two ends of the guide rail 200 are provided with a limiting structure 210, and the limiting structure 210 may be plate-shaped, strip-shaped, or a protrusion-like structure. The limiting structure 210 is used for limiting the displacement of the clamping jaw 300, preventing the clamping jaw 300 from being separated from the guide rail 200 and improving the safety. In other embodiments, the limit structure 210 can also be a limit sensor, and when the clamping jaw 300 exceeds the stroke, the limit sensor can send a signal to control the driving device 400 to stop driving and simultaneously prompt the overtravel.

Referring to fig. 2 and 4, the cam 330 is provided with a mounting hole, the clamping assembly includes a bearing 335, and the bearing 335 is disposed in the mounting hole and sleeved on the rotating shaft 322, so that the cam 330 can be rotatably connected to the rotating shaft 322. It can be understood that the bearing 335 is used to reduce the friction coefficient between the cam 330 and the rotating shaft 322, improve the rotation precision, and prevent the cam 330 from being stuck and losing the buffering effect.

Referring to fig. 2 and 4, in some embodiments, the mounting base 100 includes a guide 120 and a moving member 110, the moving member 110 is sleeved on the guide 120, wherein the moving member 110 can move along the length direction of the guide 120 to adjust the overall length of the mounting base 100 to meet different working requirements. In other embodiments, the guide member 120 and the moving member 110 are both provided with a plurality of connecting holes 111, the connecting holes 111 are arranged at intervals along the length direction of the guide member 120 and the moving member 110, and after the position between the moving member 110 and the guide member 120 is adjusted, the position between the moving member 110 and the guide member 120 can be fixed by the fastening member 130 penetrating through the connecting holes 111. The position between the moving member 110 and the guiding member 120 can be adjusted to meet different clamping requirements.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims

1. A gripping grip, comprising:

a mounting seat;

the guide rails are fixedly connected with the mounting seat;

2. The clamping gripper as claimed in claim 1, characterized in that said gripping jaws comprise torsion springs, said torsion springs being sleeved on said rotating shaft, said torsion springs being adapted to reposition said cam.

3. The clamping gripper as claimed in claim 2, characterized in that said connecting member is provided with a first limiting groove, said cam is provided with a second limiting groove, said torsion spring comprises a first radial arm and a second radial arm, said first radial arm being arranged in said first limiting groove, said second radial arm being arranged in said second limiting groove.

4. A gripping grip according to claim 1 in which the outer periphery of the abutment is involute in profile.

5. The gripping gripper of claim 1, wherein the portion of the cam protruding from the connector is provided with a plurality of grooves spaced along a periphery of the cam, the cam further comprising a slip resistant member, a portion of the slip resistant member being fixedly attached to the grooves, and another portion of the slip resistant member protruding from the grooves in the gripping direction.

6. The clamping grip of claim 5 wherein the recess includes a first slot and a second slot, the first slot being in communication with the second slot, a lower surface of the first slot forming an angle a with a lower surface of the second slot, satisfying 0 ° < a <180 °.

7. The gripping gripper according to claim 1, characterized in that said drive means comprise motors and screws, corresponding to the number of said jaws, said motors being fixedly connected to said mounting seat, the output end of said motors being fixedly connected to one end of said screws, said screws being threaded to said slides.

8. The gripping hand according to claim 1, wherein the connecting members include at least three connecting plates spaced apart along the width of the guide rail, and at least two sets of gripping elements are provided between adjacent connecting plates.

9. The gripping gripper of claim 1, wherein the cam portion extends outwardly to form a first stop portion, the connecting member is provided with a first stop, the first stop portion is engageable with the first stop to limit the angle of rotation of the cam in a first direction, the cam portion projects outwardly to form a second stop portion, the connecting member is provided with a second stop, the second stop portion is engageable with the second stop to limit the angle of rotation of the cam in a second direction, the first direction being opposite the second direction.

10. The gripping tongs of claim 1, wherein the mounting seat includes a fastener, a guide and a moving member, the moving member is sleeved on the guide, the moving member is capable of moving along the length direction of the guide to adjust the overall length of the mounting seat, the moving member and the guide are both provided with a plurality of connecting holes along the length direction, and the fastener is inserted into the connecting holes to fix the relative positions of the moving member and the guide.