CN203918820U - Locking pliers - Google Patents

Abstract

The utility model discloses a pair of pliers, which comprises a main pliers body, a movable claw, a movable handle, a connecting rod, a wedge-shaped piece and an adjusting device. When the jaw is the largest, the vise satisfies the following relationship: H/D ₁ ≥0.5, (D ₂ +D ₃ )/D ₁ ≤3.1, D ₂ /D ₃ ≥0.45, where H is the center of the first pivot to The distance of the axis X of the fixed handle passing through the center of the fourth pivot, _D1 is the distance between the center of the first pivot to the center of the second pivot, _D2 is the distance between the center of the second pivot and the center of the third pivot D ₃ is the distance between the center of the third pivot and the center of the fourth pivot. The maximum opening angle of the jaws of the pliers of the utility model can reach 49°, and can effectively and conveniently clamp large objects. The clamping force is adjustable and has nothing to do with the size of the clamped workpiece, so it is beneficial to clamp objects of different sizes. In addition, when the jaw is the largest, the angle between the movable handle and the fixed handle is small, which is convenient for one-handed operation.

Description

Pliers

technical field

The utility model relates to hardware tools, in particular to a pair of pliers.

Background technique

Existing pliers are generally composed of fixed jaws, movable jaws, fixed handles, movable handles, and adjusting screws. During use, the workpiece can be clamped by holding the locking mechanism tightly, and the workpiece can be loosened by opening the locking mechanism. However, due to the small amount of opening, it cannot hold large objects, so there are certain defects, and the scope of use is limited.

Contents of the invention

Aiming at the deficiencies in the prior art, the purpose of the utility model is to provide a pliers with simple structure, reasonable design, low manufacturing cost and the ability to clamp large objects.

Another object of the present utility model is to provide a powerful pliers with simple structure, adjustable jaw size and large jaw opening.

Another object of the present utility model is to provide a pair of pliers with relatively large clamping force and convenient for clamping large-sized workpieces.

In order to achieve the above object, the utility model provides a pair of pliers, comprising:

The main pliers body, the main pliers body is formed by fixing the fixed claws and the fixed handle, and the fixed handle has a square groove;

a movable claw, the movable claw is connected to the main pliers body through a first pivot, and can cooperate with the fixed claw to form a jaw;

a movable handle, the movable handle is connected to the movable claw through a second pivot, the movable handle has a groove, and the groove extends along the movable handle;

a wedge, the wedge is arranged in the square groove of the fixed handle, including a first wedge and a second wedge;

A connecting rod, the front end of the connecting rod is connected to the movable handle through a third pivot, the rear end of the connecting rod extends away from the direction of the jaw, and the rear end is connected to the first connecting rod through a fourth pivot. Wedge block connection;

The pliers are configured such that when the jaw reaches the maximum, the pliers satisfy the following relationship:

H/D ₁ ≥0.5, (D ₂ +D ₃ )/D ₁ ≤3.1, D ₂ /D ₃ ≥0.45

In the above formula, H is the distance from the center of the first pivot to the axis X of the fixed handle passing through the center of the fourth pivot, and _D1 is the distance from the center of the first pivot to the second The distance between pivot centers, D ₂ is the distance between the second pivot center and the third pivot center, D ₃ is the distance between the third pivot center and the fourth pivot center distance between.

Further, when a force is applied to the movable handle, the movable handle rotates toward the fixed handle until the center of the third pivot falls between the center of the second pivot and the center of the fourth pivot. When the centers are on a straight line, the tongs are in the first critical state, that is, the tongs can be locked; continue to turn the movable handle to the fixed handle to make the center of the third pivot out of the When the center of the second pivot and the center of the fourth pivot form a straight line, the tongs are in a locked state, and at this time, the movable handle, the movable claw and the connecting rod are locked.

Further, the connecting rod has a first protrusion, the first protrusion is close to the front end of the connecting rod, when the pliers is in the locked state, the first protrusion is placed on the movable handle. inside the groove.

Furthermore, a small handle is also provided in the groove of the movable handle, and the small handle has a front end protruding toward the direction of the movable claw; when the pliers are in the locked state, the The first protrusion is in contact with the front end of the small handle.

Further, the small handle is connected with the movable handle through a pin rod in the groove.

Further, the front end of the small handle can push the first protrusion out of the groove, so that the third pivot can move away from the first pivot until the third pivot When the center of the pliers falls on the straight line formed by the center of the second pivot and the center of the fourth pivot, the pliers are in the second critical state, that is, the pliers can be unlocked. The movable handle makes the center of the third pivot deviate from the straight line formed by the center of the second pivot and the center of the fourth pivot, and the pliers will be in an unlocked state, that is, the movable handle , the movable claw and the connecting rod can pivot freely.

Further, the pliers also include an adjustment device, and the adjustment device is threadedly connected with the second wedge block;

Further, when the movable handle is turned to switch the jaw from opening to closing, the adjusting device applies a pulling force to the second wedge to move the second wedge closer to the jaw.

Further, the opening refers to the state of the jaws when the movable jaw is away from the fixed jaw; the closing refers to the state of the pliers when the movable jaw is close to the fixed jaw. state of the mouth.

Further, the adjusting device includes screws, connecting parts and springs.

Further, the spring is a tension spring.

Further, the connecting rod has a second protrusion, and the second protrusion is close to the rear end of the connecting rod. When the lever can pivot, the second protrusion can contact the head of the screw and apply pressure to the head, thereby pushing the second wedge to move away from the jaw; when the pliers are in In the locked state, that is, when the movable handle, the movable claw and the connecting rod are locked, the second protrusion is separated from the head.

Further, the second wedge-shaped block has a protruding portion, the protruding portion is formed by extending the second wedge-shaped block, the protruding portion has a threaded hole, and the screw passes through the threaded hole and the protruding portion Some threaded connections.

Further, the connecting part is formed by connecting the first part and the second part.

Further, the first part extends toward the jaw and is sleeved on the connecting rod and hooked on the hook at one end of the spring; the second part is sleeved on the screw rod of the screw and placed Between the head of the screw and the protruding part.

Further, the hook at the other end of the spring is hung on the movable claw.

Further, the square groove has a first surface and a second surface, the first surface is set to be opposite to and separated from the second surface, and the first surface and the second surface are along the length of the fixed handle direction extension.

Further, the first wedge block and the second wedge block are arranged between the first surface and the second surface.

Further, both the first wedge block and the second wedge block have a wide end and a narrow end.

Further, the wide end of the first wedge is set towards the fixed claw, and the wide end of the second wedge is set away from the fixed claw.

Further, a partition plate is provided between the first wedge block and the second wedge block, and the partition plate has an upper surface and a lower surface parallel to each other, when the first wedge block passes through the When the partition plate presses the second wedge block, the upper surface is in contact with the first wedge block, and the lower surface is in contact with the second wedge block; each of the two sides of the partition plate has a The protrusion is embedded on the fixed handle.

Further, the side of the fixed handle has an elongated hole, and the protrusion is embedded in the elongated hole, so that the partition plate can only move in translation relative to the fixed handle along the elongated hole.

Further, the pliers also include an adjustment device and the object to be clamped. During the process of turning the movable handle to open the jaws to clamp the object to be clamped, the adjustment device makes the second wedge block moves toward the jaws while the link moves the first wedge block away from the jaws until the first wedge block contacts and squeezes the second wedge block through the divider plate Block, the extrusion force of the first wedge-shaped block to the second wedge-shaped block is transmitted to the movable claw through the connecting rod and the movable handle in turn, so that the movable claw moves toward the fixed claw The claw moves, and when the movement of the movable claw to the fixed claw is hindered by the clamped workpiece, a clamping force will be generated on the clamped workpiece.

Further, the adjustment device includes a screw, the screw is screwed to the end of the second wedge block, and the distance between the head of the screw and the end of the wedge block is adjusted in relation to the The magnitude of the clamping force is inversely proportional.

Further, the fixed claw and the fixed handle are integrally formed.

Further, both the fixed claw and the movable claw are provided with teeth to increase friction with the workpiece to be clamped.

Further, the maximum opening angle of the jaws can reach 49°.

Further, the first pivot shaft, the second pivot shaft, the third pivot shaft and the fourth pivot shaft are all set such that the diameters at both ends are larger than the diameter at the middle.

The utility model has the following advantages:

(1) The maximum included angle between the movable claw and the fixed claw of the pliers of the present utility model can reach 49°, which can effectively and conveniently clamp large objects;

(2) The size of the clamping force can be adjusted by turning the screw. After the position of the screw is adjusted, the size of the clamping force remains unchanged, that is, the clamping force produced by the pliers of the present utility model has nothing to do with the size of the clamped workpiece. Thereby the large pliers of the utility model can all be clamped well to the object of different size.

(3) When the opening of the pliers of the utility model reaches the maximum, the angle between the movable handle and the fixed handle is small, which is convenient for one-handed operation.

Other features and advantages of the utility model can be fully understood through the following detailed description of specific embodiments of the utility model in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is a kind of schematic diagram of the pliers in the preferred embodiment of the present utility model being in the closed state of the jaws; Fig. 2 is a schematic diagram of the pliers in Fig. 1 being at the maximum of the jaws;

Fig. 3 is another schematic view of the pliers in the embodiment of the present invention;

Fig. 4 is a sectional view along A-A direction among Fig. 1;

Fig. 5 is a three-dimensional exploded view of the pliers in the embodiment of the present invention;

Fig. 6 is another three-dimensional exploded view of the pliers in the embodiment of the present invention;

Fig. 7 is a schematic diagram of the main pliers body and its connecting parts in the embodiment of the present invention;

Fig. 8 is a three-dimensional exploded view of the embodiment in Fig. 7;

FIG. 9 is a schematic diagram of a clamped workpiece 300 when the pliers according to a preferred embodiment of the present invention are clamped.

Detailed ways

Below in conjunction with accompanying drawing, the embodiment of the present utility model is described in detail, and present embodiment is carried out under the premise of technical scheme of the present utility model, has provided detailed implementation mode and concrete operation process, but the protection scope of the present utility model is not Limited to the following examples.

As shown in Fig. 1 and Fig. 2, in a preferred implementation of the present utility model, a kind of pliers 200 is provided, comprising main pliers body 100, movable claw 3, movable handle 4, wedge-shaped piece and connecting rod 5, the main The pliers body 100 is composed of a fixed jaw 1 and a fixed handle 2 , and the fixed handle 2 has a square groove 50 . The movable claw 3 is connected with the main jaw body 100 through the first pivot 12, and can cooperate with the fixed claw 1 to form a jaw. The movable handle 4 is connected to the movable claw 3 through the second pivot 13 , and the movable handle 4 has a groove 40 extending along the movable handle 4 . The wedges are arranged in the square groove 50 of the fixed handle 2 and include a first wedge 6 and a second wedge 7 . The front end of the connecting rod 5 is connected to the movable handle 4 through the third pivot 14 , the rear end of the connecting rod 5 extends away from the direction of the jaw, and the rear end is connected to the first wedge 6 through the fourth pivot 15 .

When jaw reaches maximum (referring to Fig. 2), the vise of present embodiment satisfies following relation:

H/D ₁ ≥0.5, (D ₂ +D ₃ )/D ₁ ≤3.1, D ₂ /D ₃ ≥0.45………..(1)

In formula (1), H is the distance from the center of the first pivot 12 to the axis X of the fixed handle 2 passing through the center of the fourth pivot 15, and _D1 is the center of the first pivot 12 to the center of the second pivot 13 D ₂ is the distance between the center of the second pivot 13 and the center of the third pivot 14, D ₃ is the distance between the center of the third pivot 14 and the center of the fourth pivot 15 (see Figure 1 ).

When the existing pliers clamp workpieces of different sizes, it is often necessary to adjust the screw to achieve different jaw openings, but in the embodiment of the utility model, the jaws of the pliers can be adjusted automatically according to the size of the workpiece to be clamped. Adaptive adjustment, that is, the opening of the jaws of the pliers only needs to be adjusted to the size of the workpiece by pivoting between the movable jaw 3 and the fixed jaw 1 . The pliers of this embodiment utilize the relationship in formula (1) to set the relative positions between the first pivot 12, the second pivot 13, the third pivot 14 and the fourth pivot 15, and can realize the maximum of 49°. Jaw opening angle, so the pliers of this embodiment can clamp large-sized objects very conveniently.

As shown in Figures 3 to 8, the pliers 200 of the embodiment of the utility model includes a fixed jaw 1, a fixed handle 2, a movable jaw 3 and a movable handle 4, and the fixed jaw 1 is fixed to the fixed handle 2 by riveting or welding. connect. The movable jaw 3 and the fixed jaw 2 are connected together through the first pivot 12, the movable jaw 3 can engage with the fixed jaw 1, and can rotate relative to the fixed jaw 1 through the first pivot 12, thereby causing the pliers The opening and closing of the mouth. Both the fixed jaw 1 and the movable jaw 3 are provided with teeth at the positions where the object is clamped, which can increase the friction between the fixed jaw 1, the movable jaw 3 and the clamped workpiece, so as to facilitate better clamping of the object. The movable handle 4 is connected with the movable claw 3 through the second pivot 13 . A hanging hole 25 is arranged on the movable claw 3 .

A square groove 50 is provided on the fixed handle 2. The square groove 50 has a first surface 51 and a second surface 52. The first surface 51 is set to be opposite to and separated from the second surface 52. The first surface 51 and the second surface 52 are along the The length direction of the fixed handle 2 extends. The first wedge block 6 and the second wedge block 7 are disposed between the first surface 51 and the second surface 52 and both have a wide end and a narrow end, the width of the wide end is greater than the width of the narrow end. The wide end of the first wedge 6 is arranged towards the fixed claw 1 , while the wide end of the second wedge 7 is arranged away from the fixed claw 1 . A partition plate 19 is disposed between the first wedge block 6 and the second wedge block 7 , preferably, the partition plate 19 is a metal plate. Dividing plate 19 has upper and lower surface, when first wedge-shaped piece 6 pressed second wedge-shaped piece 7 by dividing plate 19 (referring to Fig. 4), the upper surface of dividing plate 19 contacts with first wedge-shaped piece 6, The lower surface of the dividing plate 19 is in contact with the second wedge block 7, and the two sides of the dividing plate 19 each have a protrusion 22, and the protrusion 22 is embedded in the elongated hole 20 on the side of the fixed handle 2, thereby The partition plate 19 can only move in translation relative to the fixed handle 2 along the elongated hole 20 .

The pliers 200 of this embodiment also includes a connecting rod 5, the front end of the connecting rod 5 is connected with the movable handle 4 through the third pivot 14, and the fourth pivot 15 connects the rear end of the connecting rod 5 with the first wedge block 6, And the connecting rod 5 can pivot relative to the first wedge block 6 .

In the embodiment of the present utility model, the first pivot shaft 12, the second pivot shaft 13, the third pivot shaft 14 and the fourth pivot shaft 15 are all set so that the diameters at both ends are greater than the diameter of the middle part, which can be rivets, and in other In an embodiment, the fastener may also be composed of a nut and a nut, and the diameter of the middle part of each pivot is smaller than the diameter of each pivot hole, so as to facilitate the pivoting of each component at each pivot.

The pliers of this embodiment also includes an adjusting device, preferably, the adjusting device includes a screw 8 , a connecting part 9 and a spring 10 . In a preferred embodiment of the present invention, the spring 10 is a tension spring. The second wedge block 7 has a protruding portion 24 , which is formed by extending from the second wedge block 7 , and has a threaded hole through which the screw 8 is threadedly connected with the protruding portion 24 . The connection part 9 has a first portion 91 extending toward the jaws, and a second portion 92 . The first part 91 is sleeved on the connecting rod 5 and hooked on the hook at one end of the spring 10, the second part 92 is sleeved on the screw rod of the screw 8 and placed on the head 81 of the screw 8 and the protruding part 24 of the second wedge block 7 between. The hook at the other end of the spring 10 is hung on the hanging hole 25 of the movable claw 3 .

In the embodiment of the present utility model, when the operator applies force to the movable handle 4 to make it rotate towards the fixed handle 2 through the second pivot, the third pivot 14 approaches the first pivot 12 until the third pivot When the center of 14 falls on the straight line formed by the center of the second pivot 13 and the center of the fourth pivot 15, the forceps are in the first critical state, that is, the forceps can be locked; continue to rotate the movable handle to the fixed handle 3 4 When the distance between the third pivot 14 and the first pivot 12 is minimized and the center of the third pivot 14 deviates from the straight line formed by the center of the second pivot 13 and the center of the fourth pivot 15, the forceps In the locked state, the movable handle 4, the movable claw 3 and the connecting rod 5 are locked.

The connecting rod 5 is provided with a first protrusion 17. When the movable handle 4 is rotated towards the fixed handle 2, the connecting rod 5 pivots under the action of the third pivot 14 and the fourth pivot 15, so that the first protrusion 17 17 moves towards the groove 40 of the movable handle 4 until it enters the groove 40 to lock the pliers.

A small handle 11 is arranged in the groove 40 of the movable handle 4 , and the small handle 11 is installed together with the movable handle 4 through a pin rod 18 . The small handle 11 has a front end 23 protruding toward the movable claw 3. When the tongs are in a locked state, the first protrusion 17 of the connecting rod 5 contacts the front end 23 of the small handle 11. At this time, if a force is applied to the small handle 11 to make the small handle 11 pivot toward the movable handle 4, by the principle of leverage, the force applied to the small handle 11 is applied to the first protrusion 17 through the front end 23, and the front end 23 can be easily The first protrusion 17 is pushed out from the groove 40 so that the third pivot 14 can move away from the first pivot 12 until the center of the third pivot 14 falls on the center of the second pivot 13 and the fourth pivot 15 When on the straight line formed by the centers of the pliers, the pliers are in the second critical state, that is, the pliers can be unlocked. At this time, the movable handle 4 is turned to make the third pivot 14 continue to move away from the first pivot 12 until the third pivot 14 If the center deviates from the straight line formed by the center of the second pivot 13 and the center of the fourth pivot 15, the tongs will be in an unlocked state, that is, the movable handle 4, the movable claw 3 and the connecting rod 5 can pivot freely.

The connecting rod 5 is also provided with a second protrusion 16. When the pliers are in the unlocked state, the second protrusion 16 can contact the head 81 of the screw 8 and apply pressure to the head 81, thereby pushing the second wedge 7 away from The jaws move. When the pliers are in the locked state, the second protrusion 16 is separated from the head 81 of the screw 8, and no force is exerted by the two.

During actual operation, the operator can apply force to the movable handle 4 to make the movable handle 4 turn toward or away from the fixed handle 2, so that the jaws are switched from open to closed or from closed to open. Opening here refers to the state of the jaws when the movable jaw 3 is away from the fixed jaw 1, and closing refers to the state of the jaws when the movable jaw 3 is close to the fixed jaw 1. FIG. 9 is a schematic diagram of the pliers 200 clamping the workpiece 300 according to the preferred embodiment of the present invention. When the movable handle 4 is turned to open the jaws to clamp the clamped workpiece 300, that is, to rotate the movable handle 4 to make the movable jaw 3 change from being far away from the fixed jaw 1 to being close to the fixed jaw 1 to clamp the clamped workpiece 300 , the adjustment device exerts a pulling force on the second wedge 7, so that the second wedge 7 moves toward the jaws, and at the same time, the connecting rod 5 pushes the first wedge 6 to move away from the jaws, when the first wedge 6 moves to the contact separation plate 19, the first wedge block 6 presses the partition plate 19 to move until the partition plate 19 contacts the second wedge block 7, if the first wedge block 6 continues to move away from the jaws, the first wedge block 6 will pass through The partition plate 19 compresses the second wedge block 7 . The extrusion force of the first wedge-shaped block 6 to the second wedge-shaped block 7 is transmitted to the movable jaw 3 through the connecting rod 5 and the movable handle 4 in turn, so that the movable jaw 3 moves to the fixed jaw 1. When the movable jaw 3 moves toward When the movement of the fixed jaw 1 is hindered by the workpiece 300 to be clamped, a clamping force will be generated on the workpiece 300 to be clamped.

In the embodiment of the present utility model, the clamping force of the pliers 200 on the clamped workpiece 300 has nothing to do with the size of the clamped workpiece 300, and the clamping force is realized by the screw 8 in the adjusting device. The magnitude of the clamping force depends on the distance between the protruding portion 24 of the second wedge 7 and the head 81 of the screw 8 . When the head 81 of the screw 8 is turned so that its head 81 faces the jaws away from the protruding portion 24 of the second wedge 7, the second wedge 7 moves backward away from the jaws, since the second wedge 7 has a wide end and the narrow end, and the wide end is the end away from the fixed claw 1, so the farther the second wedge moves backward, the farther the first wedge 6 needs to move backward to contact the second wedge 7 and A pressing force is generated on the second wedge block 7 . And when the first wedge block 6 moved farther back, the line between the center of the second pivot 13 and the center of the third pivot 14 and the center of the third pivot 14 and the center of the fourth pivot 15 The larger the included angle, the smaller the deformation of the connecting rod 5 caused by the first wedge block 6 extruding the second wedge block 7, so the active force transmitted to the movable claw 3 by the movable handle 4 is smaller, and the movable claw 3 moves to The smaller the moving distance of the fixed claw 1 is, the smaller the clamping force on the clamped workpiece 300 is.

On the contrary, when turning the screw 8 to make its head 81 deviate from the jaws and approach the protruding portion 24 of the second wedge block 7, the second wedge block 7 moves forward near the jaws, and the closer the second wedge block is to the jaws, The first wedge block 6 moves back a small distance and can contact the second wedge block 7 and generate a pressing force on the second wedge block 7 . When the first wedge block moved forward to get closer to the jaws, the line between the center of the second pivot 13 and the center of the third pivot 14 and the center of the third pivot 14 and the center of the fourth pivot 15 The smaller the angle between them, the greater the deformation of the connecting rod 5 caused by the first wedge-shaped block 6 pressing the second wedge-shaped block 7, so the active force transmitted to the movable claw 3 through the movable handle 4 is greater, and the movable claw 3 The greater the distance moved to the fixed jaw 1, the greater the clamping force on the workpiece 300 to be clamped.

For clamped workpieces 300 of different sizes, as long as the distance between the head 81 of the screw 8 and the protruding portion 24 of the second wedge block 7 is fixed, the clamping force on the clamped workpiece is fixed.

In addition, in the embodiment of the present utility model, when the opening of the pliers 200 reaches the maximum, the angle between the movable handle 4 and the fixed handle 2 is smaller than that of the existing pliers, thus facilitating one-handed operation.

The preferred specific embodiments of the present utility model have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the utility model without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the utility model through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection defined by the claims .

Claims (16)

1. A kind of forceps, is characterized in that, comprises: The main pliers body, the main pliers body is formed by fixing the fixed claws and the fixed handle, and the fixed handle has a square groove; a movable claw, the movable claw is connected to the main pliers body through a first pivot, and can cooperate with the fixed claw to form a jaw; a movable handle, the movable handle is connected to the movable claw through a second pivot, the movable handle has a groove, and the groove extends along the movable handle; a wedge, the wedge is arranged in the square groove of the fixed handle, including a first wedge and a second wedge; A connecting rod, the front end of the connecting rod is connected to the movable handle through a third pivot, the rear end of the connecting rod extends away from the direction of the jaw, and the rear end is connected to the first connecting rod through a fourth pivot. Wedge block connection; The pliers are configured such that when the jaw reaches the maximum, the pliers satisfy the following relationship: H/D ₁ ≥0.5, (D ₂ +D ₃ )/D ₁ ≤3.1, D ₂ /D ₃ ≥0.45 In the above formula, H is the distance from the center of the first pivot to the axis X of the fixed handle passing through the center of the fourth pivot, and _D1 is the distance from the center of the first pivot to the second The distance between pivot centers, D ₂ is the distance between the second pivot center and the third pivot center, D ₃ is the distance between the third pivot center and the fourth pivot center distance between. 2. The pliers according to claim 1, wherein when a force is applied to the movable handle, the movable handle rotates toward the fixed handle until the center of the third pivot falls on the first pivot. When the centers of the two pivots and the center of the fourth pivot are on a straight line, the pliers are in the first critical state, that is, the pliers can be locked; continue to rotate the movable handle to the fixed handle. When the handle makes the center of the third pivot deviate from the straight line formed by the center of the second pivot and the center of the fourth pivot, the pliers are in a locked state. At this time, the movable handle, the The movable claw and the connecting rod are locked. 3. The pliers according to claim 2, wherein the connecting rod has a first protrusion, the first protrusion is close to the front end of the connecting rod, when the pliers are in the locked state, The first protrusion is placed in the groove of the movable handle. 4. The pliers according to claim 3, wherein a small handle is also provided in the groove of the movable handle, and the small handle has a front end protruding toward the direction of the movable claw; When the pliers are in the locked state, the first protrusion is in contact with the front end of the small handle. 5. The pliers according to claim 4, wherein the front end of the small handle can push the first protrusion out of the groove, so that the third pivot can be away from the The first pivot moves until the center of the third pivot falls on the straight line connecting the center of the second pivot and the center of the fourth pivot, the tongs are in the second critical state , that is, the pliers can be unlocked. At this time, the movable handle is turned so that the center of the third pivot is separated from the straight line formed by the center of the second pivot and the center of the fourth pivot. The pliers will be in an unlocked state, that is, the movable handle, the movable claw and the connecting rod can pivot freely. 6. The pliers according to claim 1, characterized in that, the pliers further comprise an adjustment device, and the adjustment device is threadedly connected with the second wedge block. 7. The pliers according to claim 6, characterized in that, during the process of turning the movable handle to switch the jaws from open to closed, the adjusting device exerts a pulling force on the second wedge to make the jaws The second wedge moves closer to the jaws. 8. The pliers according to claim 6, wherein the adjusting device comprises a screw, a connecting member and a spring. 9. The pliers according to claim 8, wherein the connecting rod has a second protrusion, the second protrusion is close to the rear end of the connecting rod, when the pliers are in the unlocked state, the When the movable handle, the movable claw and the connecting rod can pivot, the second protrusion can contact the head of the screw and apply pressure to the head, thereby pushing the second wedge block Move away from the jaws; when the pliers are in a locked state, that is, when the movable handle, the movable claw and the connecting rod are locked, the second protrusion is separated from the head. 10. The powerful pliers according to claim 8, wherein the second wedge block has a protruding portion, the protruding portion is formed by extending from the second wedge block, and the protruding portion has a threaded hole , the screw is threadedly connected with the protruding part through the threaded hole. 11. The pliers according to claim 10, characterized in that, the connecting part is formed by connecting a first part and a second part, and the first part extends toward the jaw and is sleeved on the connecting rod And hooked on the hook at one end of the spring, the second part is sleeved on the screw rod of the screw and placed between the head of the screw and the protruding part, and the hook at the other end of the spring is hung on the on the movable jaw. 12. The powerful pliers according to claim 1, wherein the square groove has a first surface and a second surface, the first surface is set to be opposite to and separated from the second surface, the first surface A surface and the second surface extend along the length direction of the fixed handle, and the first wedge block and the second wedge block are arranged between the first surface and the second surface. 13. The pliers of claim 1, wherein the first wedge and the second wedge each have a wide end and a narrow end; the wide end of the first wedge is disposed toward The fixed claw, and the wide end of the second wedge is set away from the fixed claw. 14. The pliers according to claim 1, wherein a partition plate is arranged between the first wedge block and the second wedge block, and the partition plate has an upper surface and a lower surface parallel to each other. surface, when the first wedge block presses the second wedge block through the partition plate, the upper surface is in contact with the first wedge block, and the lower surface is in contact with the second wedge block ; The two sides of the partition board each have a protrusion, and the protrusion is embedded in the elongated hole on the side of the fixed handle. 15. The pliers according to claim 14, characterized in that, the pliers also include an adjusting device and the object to be clamped, and turning the movable handle causes the jaws to open to clamp the object to be clamped. During the process, the adjusting device moves the second wedge towards the jaw, and at the same time, the connecting rod moves the first wedge away from the jaw until the first wedge passes through the jaw. The partition plate contacts and squeezes the second wedge block, and the pressing force of the first wedge block on the second wedge block is sequentially transmitted to the movable card through the connecting rod and the movable handle. Claw, so that the movable jaw moves to the fixed jaw, when the movement of the movable jaw to the fixed jaw is hindered by the clamped workpiece, clamping will occur on the clamped workpiece force. 16. The pliers according to claim 15, wherein the adjustment device comprises a screw, the screw is screwed to the end of the second wedge block, and the head of the screw is adjusted to the wedge. The distance between the ends of the blocks is inversely proportional to the magnitude of the clamping force.