An installation tool for securing a cotter pin to a bolt and nut assembly

Abstract

The present invention discloses an installation tool for fixing a cotter pin to a bolt and nut assembly. The movable pliers are rotatably fixed to the fixed pliers via a pliers shaft. Steps I and II are raised on opposing surfaces of the upper ends of the fixed and movable pliers, respectively. The inner end planes I and II of steps I and II are arranged oppositely, and the upper end of inner end plane I protrudes a step III that abuts the lower end surface of the workpiece nut. A center positioning block is positioned within a dovetail groove of the positioning block, with its front end capable of extending into and abutting the cotter pin fixing groove of the workpiece nut. The front end of an adjusting screw threadedly connected within the fixed pliers is fixed within the center positioning block. A protrusion with a cutting edge protrudes from one end of a conversion head body. The conversion head body is detachably fixed within a through slot of the movable pliers. During operation, the fixed pliers body and the workpiece nut are attracted together. This device does not damage the threads of the bolt and nut during assembly, thereby improving assembly quality. The device is less restricted by radial space between the bolts, making assembly simple and convenient.

Description

Technical Field

[0001] The invention belongs to the field of mechanical assembly and relates to an installation tool for fixing a cotter pin on a bolt and nut assembly. Background Art

[0002] The most common threaded connection method is a bolt and nut combination. Under static loads and with minimal fluctuations in operating temperature, these connections will not loosen on their own. However, under shock, vibration, or variable loads, as well as under significant temperature fluctuations, these connections may loosen, impacting operation and even causing accidents. To ensure safe and reliable connections, effective anti-loosening measures are often implemented. Cotter pins are widely used in the machinery industry and are the most common anti-loosening method.

[0003] The material of the cotter pin is usually austenitic stainless steel 0Cr18Ni9Ti and 1Cr18Ni9Ti. It is a metal hardware, commonly known as a spring pin, used to prevent threaded connections from loosening. The cotter pin is inserted into the nut groove and the hole at the tail of the bolt, and the tail of the cotter pin is broken open and bent into the nut groove to prevent the nut and bolt from rotating relative to each other.

[0004] The general method for installing a cotter pin is to manually pry apart the two legs after inserting the cotter pin. Depending on the size and hardness of the cotter pin, bend it with pliers or by hand until the two legs are flush against the outer hexagonal edge of the nut. Finally, use a hammer and a flat-blade screwdriver or chisel to remove any excess material and bend the tail end into the groove of the hexagonal slot nut. This method is currently the most commonly used, but it is difficult to control the force and can easily damage the threads. Furthermore, the flat-blade screwdriver or chisel must be perpendicular to the thread axis, which is limited by the radial space of the bolt. Summary of the Invention

[0005] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art and to provide an installation tool for fixing a cotter pin on a bolt and nut assembly. When the cotter pin is assembled to prevent the nut and bolt from rotating relative to each other, the installation device will not damage the threads of the bolt and nut, thereby improving the assembly quality. The device is less restricted by the radial space of the bolt and is simple and convenient to assemble. It can be applied to nut and cotter pin assemblies of various specifications.

[0006] To achieve the above-mentioned purpose, the technical solution of the present invention is: an installation tool for fixing a cotter pin on a bolt and nut assembly, comprising a fixed part, a movable part and a clamp shaft; the fixed part comprises a fixed clamp body, a center positioning block and an adjusting screw; the movable part comprises a movable clamp body, a connecting shaft and a conversion head; the vertical cross-section of the fixed clamp body is in the shape of a "ㄣ" and the movable clamp body is a rectangular parallelepiped, and the two are connected by a clamp shaft in the middle, one end of the clamp shaft is fixed to the fixed clamp body and the other end is rotatably fixed to the movable clamp body; the upper ends of the fixed clamp body and the movable clamp body are Steps I and II are raised on the opposite surfaces of the assembly respectively; the inner end plane I of the fixed pliers body at step I and the inner end plane II of the movable pliers body at step II are arranged oppositely; and the upper end of the inner end plane I protrudes a step III that fits the lower end surface of the workpiece nut; the center positioning block is a dovetail shape with a small front end and a large rear end; the inner end plane I of the fixed pliers body is provided with a dovetail groove at the upper end of the upper end of step III that passes through the upper end surface and fits the clearance of the rear end of the center positioning block, and a threaded hole perpendicular to the bottom wall of the dovetail groove and fits the adjusting screw is provided on the bottom wall of the dovetail groove; the rear end of the center positioning block is provided with a dovetail groove The cam is in the dovetail groove, and its front end can be inserted into and connected to the cotter pin fixing groove of the workpiece nut, and its rear end is provided with a threaded groove; the adjusting screw is threadedly connected to the threaded hole of the fixed pliers body, and the front end is fixed in the threaded groove of the center positioning block; the conversion head includes a conversion head body, and the conversion head body protrudes a protrusion with an angular front end at one end relative to the workpiece nut; the front end of the protrusion is a bent inclined surface, and the plane in contact with the cotter pin is an extrusion surface, and a blade is provided on the front edge where the bent inclined surface intersects with the opposite surface of the extrusion surface, and the thickness of the protrusion and the radius of the cotter pin add up to the workpiece. The width of the cotter pin fixing groove of the nut is matched, and a slot entry limit mechanism is provided on the protrusion; the conversion head body is detachably fixed in the through groove opened at the upper end of the movable pliers body by the connecting shaft, and the bent inclined surface on its protrusion is arranged parallel to the inner end plane Ⅰ of the fixed pliers body; when working, the upper end of the fixed pliers body and the workpiece nut are adsorbed together, and its center positioning block is pressed against a cotter pin fixing groove of the workpiece nut but has a distance from the workpiece bolt, and the protrusion of the conversion head can squeeze one end of the cotter pin into the other opposite cotter pin fixing groove of the workpiece nut and has a distance from the workpiece bolt.

[0007] Further preferably, the structure in which the upper end of the fixed pliers body and the workpiece nut are adsorbed together is as follows: the fixed pliers body is respectively embedded and fixed with sealing gaskets on the inner end planes I on both sides of the dovetail groove, and a through ventilation channel is opened in the fixed pliers body at the raised step I, and at least one of the through ventilation channels passes through the fixed pliers body to form an external ventilation port, one of these external ventilation ports is fixed with a pipe joint connected to a vacuum pump, and the others are fixed with sealing plugs; ventilation holes are respectively opened on the two sealing gaskets, and the ventilation holes on the two sealing gaskets are connected to the ventilation channels in the fixed pliers body. When in use, as long as the pipe joint is connected to the air pump, the fixed pliers body and the nut are aligned and attached together, the vacuum pump is evacuated, and the fixed pliers body and the nut are tightly attached, and no more movement or misalignment occurs, then a series of operations such as tightening the center positioning block, opening the movable inlay, cutting, bending and squeezing the adapter to fix the cotter pin are simple, convenient and efficient.

[0008] Further preferably, the structure in which the upper end of the fixed pliers body and the workpiece nut are attracted together is as follows: the fixed pliers body is a permanent magnet, and the workpiece nut is made of a material that is attracted to magnets; the center positioning block, adjustment screw, movable pliers body, connecting shaft, conversion head, and pliers shaft are made of a material that is not attracted to magnets. Preferably, the elastic retaining ring is made of a material that is not attracted to magnets. Since nuts and bolts are mostly made of iron or stainless steel that are attracted to magnets, as long as the fixed pliers body is a permanent magnet, such nuts can be attracted, ensuring accurate alignment between the fixed pliers body and the nut, and simple and reliable fixation. However, this is not suitable for use with nuts made of materials that are not attracted to magnets.

[0009] Further preferably, the upper end of the fixed pliers and the workpiece nut are attracted together by: permanent magnets are embedded and fixed on the inner end plane I of each side of the dovetail groove of the fixed pliers, flush with the inner end plane I; the workpiece nut is made of a material that is attracted to magnets; and the fixed pliers, centering block, adjustment screw, movable pliers, connecting shaft, adapter, and pliers shaft are made of materials that are not attracted to magnets. Since nuts and bolts are mostly made of iron or stainless steel that is attracted to magnets, only two permanent magnets are needed to attract such nuts, ensuring accurate alignment between the fixed pliers and the nut, simple and reliable fixation, and easy workpiece removal. However, this is not suitable for nuts made of materials that are not attracted to magnets.

[0010] Further preferably, the specific structure in which one end of the clamp shaft is fixed to the fixed clamp body and the other end is rotatably fixed to the movable clamp body is: one end of the clamp shaft is a cylindrical shaft, and the other end is a spline shaft with one or more key protrusions; the middle relative positions of the fixed clamp body and the movable clamp body are respectively provided with mounting hole I that matches the spline shaft of the clamp shaft and mounting hole II that gap matches the cylindrical shaft of the clamp shaft; one end of the clamp shaft passes through the mounting hole I of the fixed clamp body, and the other end passes through the mounting hole II of the movable clamp body, and both ends are riveted to the fixed clamp body and the movable clamp body.

[0011] Further preferably, the movable part also includes an elastic retaining ring; one end of the connecting shaft is a square shaft and the other end is a cylindrical shaft, and a connecting shaft mounting hole with a square hole at one end and a round hole at the other end is provided on the conversion head body, and a through square hole and a through round hole are respectively provided on the two walls of the through slot II of the movable clamp body at positions corresponding to the connecting shaft mounting hole of the conversion head body; the conversion head body is placed in the through slot II, and is fixed on the two walls of the through slot II by the connecting shaft and the elastic retaining ring clamped on the end of the cylindrical shaft of the connecting shaft.

[0012] Further preferably, the angle between the bending slope of the conversion head and the opposite surface of the extrusion surface is less than 90 degrees, so as to ensure the convenience of the blade cutting.

[0013] Further preferably, the slot-entry limiting mechanism provided on the protrusion of the conversion head is configured such that: the extrusion surface is inclined at an angle of 5 to 10 degrees relative to the plane of the side edge of the workpiece nut groove, so that the thickness of the protrusion ensures that the cotter pin cannot move into the workpiece nut groove when it is squeezed into place; or the slot-entry limiting mechanism provided on the protrusion of the conversion head is configured such that a stop protrusion is provided on the convex extrusion surface and the surface opposite the extrusion surface. This provides high strength and prevents the protrusion from continuing to enter the groove after the conversion head bends the cotter pin into place, thereby damaging the threads of the bolt and nut.

[0014] During use, the adjustment screw is rotated to adjust the position of the centering block, ensuring that the centering block is in contact with the nut groove. The entire tool is then moved and, after accurate alignment, the fixed pliers body and the workpiece nut are attracted together. The movable pliers body is gripped and rotated. The blades on the adapter head interact with the sides of the nut groove to cut the end of the cotter pin to be sheared. Simultaneously, the bend bevel of the adapter head bends the cotter pin into the nut groove, and the adapter head also enters the nut groove. Driven by the bend bevel of the adapter head and pressed by its extrusion surface, the sheared end of the cotter pin is pressed against the side of the groove and compacted. The movable pliers body is then moved to disengage it from the nut, disengaging the fixed pliers body from the workpiece nut. The above steps are repeated to cut, bend, and compact the other end of the cotter pin. When assembling the cotter pin, the present invention achieves accurate alignment without damaging the threads of the bolt and nut, thereby improving assembly quality. Furthermore, due to minimal radial space restrictions on the bolt, assembly is simple and convenient, improving efficiency and saving labor. According to the different specifications of the nut, different types of conversion heads can be selected according to the size of the nut groove and the cotter pin. By replacing the conversion head, it can be applied to nut and cotter pin assemblies of various specifications, with a wide range of uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A front view of a first embodiment of the present invention;

[0016] Figure 2 This is an exploded view of the three-dimensional structure of the first embodiment of the present invention;

[0017] Figure 3 This is a front view of the first embodiment of the present invention when the workpiece processing has just been completed;

[0018] Figure 4 for Figure 3 AA cross-sectional view;

[0019] Figure 5 It is a left side view of the fixed clamp body of the present invention;

[0020] Figure 6 A top view of the fixed portion of the present invention;

[0021] Figure 7 for Figure 6 BB cross-sectional view;

[0022] Figure 8 for Figure 6 CC cross-sectional view;

[0023] Figure 9 This is a three-dimensional structural diagram of the center positioning block in the present invention;

[0024] Figure 10 It is a three-dimensional structural diagram of the clamp shaft in the present invention;

[0025] Figure 11 It is a three-dimensional structural diagram of the connecting shaft in the present invention;

[0026] Figure 12 This is a three-dimensional structural diagram of the conversion head of the present invention viewed from one direction;

[0027] Figure 13 This is a three-dimensional structural diagram of the conversion head of the present invention viewed from another direction;

[0028] Figure 14 It is a front view of a second embodiment of the present invention;

[0029] Figure 15 for Figure 14 DD cross-sectional view;

[0030] Figure 16 This is an exploded view of the three-dimensional structure of the second embodiment of the present invention;

[0031] Figure 17 This is a front view of the second embodiment of the present invention when the workpiece processing has just been completed;

[0032] Figure 18 for Figure 17 EE cross-sectional view;

[0033] Figure 19 It is a front view of a third embodiment of the present invention;

[0034] Figure 20 for Figure 19 FF cross-sectional view;

[0035] Figure 21 This is an exploded view of the three-dimensional structure of the third embodiment of the present invention;

[0036] Figure 22 This is a front view of the third embodiment of the present invention when the workpiece processing has just been completed;

[0037] Figure 23 for Figure 22 GG cross-sectional view. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and specific implementations.

[0039] Example 1, as Figure 1 Zhihe Figure 13As shown, this embodiment includes a fixed part 1, a movable part 2 and a clamp shaft 3. The fixed part 1 includes a fixed clamp body 101, a center positioning block 103 and an adjustment screw 104. The movable part 2 includes a movable clamp body 201, a connecting shaft 202 and a conversion head 203. The vertical cross-section of the fixed caliper body 101 is in the shape of a "ㄣ", and the movable caliper body 201 is a rectangular parallelepiped, and the two are connected by a caliper shaft 3 in the middle; one end of the caliper shaft 3 is fixed to the fixed caliper body 101, and the other end is rotatably fixed to the movable caliper body 201. Preferably, the specific structure is: one end of the caliper shaft 3 is a cylindrical shaft, and the other end is a spline shaft with a key (multiple keys can also be selected as needed, but because the object is small, the production process of multiple keys is cumbersome) protruding; the middle relative positions of the fixed caliper body 101 and the movable caliper body 201 are respectively provided with a mounting hole I109 that matches the spline shaft of the caliper shaft 3 and a mounting hole II207 that is clearance-matched with the cylindrical shaft of the caliper shaft 3; one end of the caliper shaft 3 is passed through the mounting hole I109 of the fixed caliper body, and the other end is passed through the mounting hole II207 of the movable caliper body, and both ends are riveted to the fixed caliper body 101 and the movable caliper body 201. The fixed jaw body 101 and the movable jaw body 201 have raised steps I 108 and II 206 on their respective mounting surfaces. The inner end plane I of the fixed jaw body 101 at step I 108 and the inner end plane II of the movable jaw body 201 at step II 206 are positioned opposite each other. The upper end of inner end plane I projects a step III 102 that mates with the lower end surface of the workpiece nut 6. The centering block 103 is dovetail-shaped, with a small front end and a large rear end. A dovetail groove 110 is formed on the upper end of inner end plane I of the fixed jaw body 101, above step III 102, extending through the upper end surface and providing a clearance fit with the rear end of the centering block 103. A threaded hole 112 is formed perpendicular to the bottom wall of dovetail groove 110 and mates with the adjusting screw 104. The rear end of the centering block 103 is positioned within dovetail groove 110, with its front end capable of extending into and contacting the cotter pin retaining groove of the workpiece nut 106. A threaded groove is formed on the rear end of the centering block 103. The adjustment screw 104 is threaded into the threaded hole 112 of the positioning block, with its front end fixed in the threaded groove of the center positioning block 103. The conversion head 203 includes a conversion head body, which has an angular protrusion protruding from the end opposite the workpiece nut 6. The front end of the protrusion is a curved bevel 208, and the plane that contacts the cotter pin 4 is an extrusion surface 210. A cutting edge 209 is provided on the front edge where the curved bevel 208 intersects the opposite surface of the extrusion surface 210. The thickness of the protrusion plus the radius of the cotter pin 4 are matched to the width of the cotter pin fixing slot in the workpiece nut 6. The protrusion is provided with a slot-entry limiter.The converter body is removably secured by a connecting shaft 202 within a through-slot formed at the upper end of the movable caliper body 201. A preferred structure includes a movable portion further comprising a circlip 205. The connecting shaft 202 is square at one end and cylindrical at the other. The converter body defines a connecting shaft mounting hole 204 with a square hole at one end and a circular hole at the other. The through-slot in the movable caliper body 201 includes a through-square hole and a through-circular hole, respectively, at positions corresponding to the connecting shaft mounting hole 204. The converter body is positioned within the through-slot and secured to the two walls by the connecting shaft 202 and the circlip 205, which is secured to the cylindrical end of the connecting shaft. The bend 208 on the protrusion of the converter body is parallel to the inner end plane I of the fixed caliper body 101. Preferably, the angle between the bend 208 of the converter body and the extrusion surface opposing surface 211 is less than 90°. The slot entry limit mechanism provided on the protrusion of the conversion head is as follows: the extrusion surface 210 has an inclination angle of any angle between 5 and 10° relative to the plane 7 where the side edge of the groove of the workpiece nut 6 is located, so that the thickness of the protrusion ensures that the extruded cotter pin cannot move into the groove of the workpiece nut when it is in place (the slot entry limit mechanism provided on the protrusion of the conversion head can also be set as a blocking protrusion provided on the convex extrusion surface and the opposite surface of the extrusion surface as needed). During operation, the upper end of the fixed caliper body 101 and the workpiece nut 6 are adsorbed together, and its preferred specific structure is: the fixed caliper body 101 is respectively embedded and fixed with a sealing gasket 105 on the inner end plane Ⅰ on both sides of the dovetail groove 110, and a through-ventilation channel 8 is opened in the fixed caliper body 101 at the raised step Ⅰ108. The through-ventilation channel 8 has at least one place (in this embodiment, there are 2 places at the top of the fixed caliper body 101, 1 place at the bend, 1 place at the outer end surface, and 1 place at the raised step Ⅰ) through the fixed caliper body 101 to form an external vent, and one of these external vents is fixed with a pipe joint 107 connected to a vacuum pump, and the other is fixed with a sealing plug 106; vent holes are respectively opened on the two sealing gaskets 105, and the vent holes on the two sealing gaskets 105 are connected to the vent channel 8 in the fixed caliper body 101. During operation, the center positioning block 103 of the fixed pliers body is pressed against a cotter pin fixing groove of the workpiece nut 6 but is spaced apart from the workpiece bolt 5. The protrusion of the conversion head 203 can squeeze one end of the cotter pin 4 into the other opposite cotter pin fixing groove of the workpiece nut 6 and is spaced apart from the workpiece bolt 5.

[0040] Example 2, as Figures 9 to 13 、 Figures 14 to 18As shown, the other structures of this embodiment are the same as those of Example 1, except that the two sealing gaskets are missing, the fixed caliper body 101 lacks a sealed ventilation channel, and there are no external vents, pipe joints, or sealing plugs. However, the fixed caliper body 101 is a permanent magnet, and the workpiece nut 6 is made of a material that is attracted to magnets. The centering block 103, adjustment screw 104, movable caliper body 201, connecting shaft 202, conversion head 203, and caliper shaft 3 are made of materials that are not attracted to magnets. Preferably, the circlip 205 is also made of a material that is not attracted to magnets.

[0041] Example 3, as Figures 9 to 13 、 Figures 19 to 23 As shown, the other structures of this embodiment are the same as those of Example 2, except that the fixed caliper body 101 is made of a material that is not attracted to magnets. Permanent magnets 113 are embedded and fixed on the inner end plane I on both sides of the dovetail groove 110 of the fixed caliper body 101, flush with the inner end plane I. The workpiece nut 6 is made of a material that is attracted to magnets. The centering block 103, adjustment screw 104, movable caliper body 201, connecting shaft 202, conversion head 203, and caliper shaft 3 are also made of a material that is not attracted to magnets. Preferably, the circlip 205 is also made of a material that is not attracted to magnets. 114 denotes a permanent magnet mounting slot provided on the inner end plane I.

[0042] Of course, the present invention has many other embodiments. Without violating the spirit and essence of the present invention, those skilled in the art may make corresponding changes and modifications based on the present invention. However, these corresponding changes and modifications should be regarded as improvements of equivalent technologies and fall within the scope of protection of the claims of the present invention.

Claims

1. A mounting tool for fixing a cotter pin to a bolt and nut assembly, characterized by: It includes a fixed part, a movable part and a clamp shaft; the fixed part includes a fixed clamp body, a center positioning block and an adjusting screw; the movable part includes a movable clamp body, a connecting shaft and a conversion head; the vertical cross-section of the fixed clamp body is in the shape of "ㄣ", and the movable clamp body is a rectangular parallelepiped, and the two are connected by a clamp shaft in the middle, one end of the clamp shaft is fixed to the fixed clamp body, and the other end is rotatably fixed to the movable clamp body; the opposite surfaces of the upper ends of the fixed clamp body and the movable clamp body are respectively raised with steps I and II; the inner end of the fixed clamp body at step I is flat The inner end plane II of the movable pliers is arranged relative to the surface I and the step II; and the upper end of the inner end plane I protrudes from the step III that fits the lower end surface of the workpiece nut; the center positioning block is in the shape of a dovetail with a small front end and a large rear end; the inner end plane I of the fixed pliers is provided with a dovetail groove that passes through the upper end surface and fits the clearance of the rear end of the center positioning block at the upper end of the upper end of the step III, and a threaded hole is provided on the bottom wall of the dovetail groove that is perpendicular to the bottom wall and fits the adjusting screw; the rear end of the center positioning block is placed in the dovetail groove, and its front end can be inserted into and contacted with the workpiece nut. The rear end of the cotter pin fixing groove is provided with a threaded groove; the adjusting screw is threadedly connected to the threaded hole of the fixed pliers body, and the front end is fixed in the threaded groove of the center positioning block; the conversion head includes a conversion head body, and the conversion head body protrudes a protrusion with an angular front end at one end relative to the workpiece nut; the front end of the protrusion is a bent inclined surface, and the plane in contact with the cotter pin is an extrusion surface, and a blade is provided on the front edge where the bending inclined surface intersects with the opposite surface of the extrusion surface. The thickness of the protrusion and the radius of the cotter pin add up to match the width of the cotter pin fixing groove of the workpiece nut, and a slot entry limit mechanism is provided on the protrusion; the conversion head body is detachably fixed in the through groove opened at the upper end of the movable pliers body by the connecting shaft, and the bent inclined surface on its protrusion is arranged parallel to the inner end plane I of the fixed pliers body; when working, the upper end of the fixed pliers body and the workpiece nut are adsorbed together, and its center positioning block is pressed against a cotter pin fixing groove of the workpiece nut but has a spacing with the workpiece bolt, and the protrusion of the conversion head can squeeze one end of the cotter pin into the other opposite cotter pin fixing groove of the workpiece nut and has a spacing with the workpiece bolt.

2. The installation tool for fixing a cotter pin to a bolt and nut assembly according to claim 1, characterized in that: The fixed clamp body is respectively embedded with and fixed with sealing gaskets on the inner end planes I on both sides of the dovetail groove, and a through ventilation channel is opened in the fixed clamp body at the raised step I, and at least one of the through ventilation channels penetrates the fixed clamp body to form an external ventilation port, one of these external ventilation ports is fixed with a pipe joint connected to a vacuum pump, and the others are fixed with sealing plugs; ventilation holes are respectively opened on the two sealing gaskets, and the ventilation holes on the two sealing gaskets are connected to the ventilation channel in the fixed clamp body.

3. The installation tool for fixing a cotter pin on a bolt and nut assembly according to claim 1 or 2, characterized in that: The specific structure in which one end of the caliper shaft is fixed to the fixed caliper body and the other end is rotatably fixed to the movable caliper body is as follows: one end of the caliper shaft is a cylindrical shaft, and the other end is a spline shaft with one or more key protrusions; a mounting hole I that matches the spline shaft of the caliper shaft and a mounting hole II that gap-fits with the cylindrical shaft of the caliper shaft are respectively provided at the middle relative positions of the fixed caliper body and the movable caliper body; one end of the caliper shaft passes through the mounting hole I of the fixed caliper body, and the other end passes through the mounting hole II of the movable caliper body, and both ends are riveted to the fixed caliper body and the movable caliper body.

4. According to the installation tool for fixing the cotter pin on the bolt and nut assembly according to claim 3, the angle between the intersection of the bent inclined surface of the conversion head and the opposite surface of the extrusion surface is less than 90°; the slot entry limiting mechanism arranged on the protrusion of the conversion head is: the extrusion surface has an inclination angle of 5 to 10° relative to the plane where the side of the workpiece nut groove is located, so that the thickness of the protrusion ensures that the cotter pin cannot move into the workpiece nut groove when it is extruded into place; or the slot entry limiting mechanism arranged on the protrusion of the conversion head is a gear protrusion arranged on the convex extrusion surface and the opposite surface of the extrusion surface.

5. The installation tool for fixing a cotter pin to a bolt and nut assembly according to claim 4, characterized in that: The movable part also includes an elastic retaining ring; one end of the connecting shaft is a square shaft and the other end is a cylindrical shaft, and a connecting shaft mounting hole with a square hole at one end and a round hole at the other end is opened on the conversion head body, and a through square hole and a through round hole are respectively opened on the two walls of the through slot II of the movable clamp body at positions corresponding to the connecting shaft mounting hole of the conversion head body; the conversion head body is placed in the through slot II, and is fixed on the two walls of the through slot II by the connecting shaft and the elastic retaining ring clamped on the end of the cylindrical shaft of the connecting shaft.

6. The installation tool for fixing a cotter pin to a bolt and nut assembly according to claim 1, characterized in that: The structure in which the upper end of the fixed pliers body and the workpiece nut are adsorbed together is: the fixed pliers body is a permanent magnet, and the workpiece nut is made of a material that is adsorbed by the magnet; the center positioning block, adjusting screw, movable pliers body, connecting shaft, conversion head and pliers shaft are made of materials that are not adsorbed by the magnet.

7. The installation tool for fixing a cotter pin to a bolt and nut assembly according to claim 1, characterized in that: The fixed pliers body is respectively embedded with and fixed with permanent magnet blocks flush with the inner end plane I on both sides of the dovetail groove, and the workpiece nut is made of a material that is attracted by magnets; the fixed pliers body, center positioning block, adjustment screw, movable pliers body, connecting shaft, conversion head and pliers shaft are made of materials that are not attracted by magnets.

8. The installation tool for fixing a cotter pin to a bolt and nut assembly according to claim 6 or 7, characterized in that: The specific structure in which one end of the caliper shaft is fixed to the fixed caliper body and the other end is rotatably fixed to the movable caliper body is as follows: one end of the caliper shaft is a cylindrical shaft, and the other end is a spline shaft with one or more key protrusions; a mounting hole I that matches the spline shaft of the caliper shaft and a mounting hole II that gap-fits with the cylindrical shaft of the caliper shaft are respectively provided at the middle relative positions of the fixed caliper body and the movable caliper body; one end of the caliper shaft passes through the mounting hole I of the fixed caliper body, and the other end passes through the mounting hole II of the movable caliper body, and both ends are riveted to the fixed caliper body and the movable caliper body.

9. According to the installation tool for fixing the cotter pin on the bolt and nut assembly according to claim 8, the angle between the intersection of the bent inclined surface of the conversion head and the opposite surface of the extrusion surface is less than 90°; the slot entry limiting mechanism arranged on the protrusion of the conversion head is: the extrusion surface has an inclination angle of 5 to 10° relative to the plane where the side of the workpiece nut groove is located, so that the thickness of the protrusion ensures that the cotter pin cannot move into the workpiece nut groove when it is extruded into place; or the slot entry limiting mechanism arranged on the protrusion of the conversion head is a gear protrusion arranged on the convex extrusion surface and the opposite surface of the extrusion surface.

10. The installation tool for fixing a cotter pin on a bolt and nut assembly according to claim 9, characterized in that: The movable part also includes an elastic retaining ring; one end of the connecting shaft is a square shaft and the other end is a cylindrical shaft, and a connecting shaft mounting hole with a square hole at one end and a circular hole at the other end is formed on the conversion head body, and a through square hole and a through circular hole are respectively formed on the two walls of the through slot II of the movable clamp body at positions corresponding to the connecting shaft mounting hole of the conversion head body; the conversion head body is placed in the through slot II, and is fixed on the two walls of the through slot II by the connecting shaft and the elastic retaining ring clamped on the end of the cylindrical shaft of the connecting shaft; the elastic retaining ring is made of a material that is not attracted by magnets.

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