A double gear and its production tooling and process

Abstract

The present application relates to a double gear and its production tooling and process, belonging to the field of double gear production. The double gear includes a fixed shaft, a first gear body is coaxially fixedly connected to the fixed shaft, a second gear body is coaxially sleeved on the fixed shaft and located on one side of the fixed shaft, and a matching knurling wheel is coaxially fixedly connected to the fixed shaft. The steps of the production process include: gear blank set, gear blank hot melting, cooling and shaping, and gear blank outer teeth cold processing. The present application directly uses the serration structure of the matching knurling wheel on the fixed shaft as a model to form the meshing gear structure of the second gear body, thereby improving the firmness of the matching state between the second gear body and the fixed shaft, and the double gear can also stably transmit greater torque.

Description

Technical Field

[0001] The present application relates to the field of production of double gears, and in particular to a double gear and its production tooling and process. Background Art

[0002] Two coaxial gears with the same module but different numbers of teeth are called duplex gears. Duplex gears are usually used in speed change mechanisms to improve the compactness of the components within the mechanism.

[0003] In the related art, a double gear used inside a motor includes a fixed shaft and two gear bodies coaxially fixed on the fixed shaft, one of which is integrally formed with the fixed shaft and both are made of metal; the other gear body is made of polymer material, and when meshing with the polymer gear body, the noise generated by the gear transmission is relatively small. A matching knurled wheel is formed on the fixed shaft, and meshing serrations for meshing with the matching knurled wheel are formed on one side of the inner ring of the polymer gear body. When the matching knurled wheel and the meshing serrations are matched with each other, the fixed shaft forms a circumferential limit on the gear body, that is, the fixed shaft can transmit torque through the gear body.

[0004] The gear body made of polymer material is usually formed by injection molding using an injection mold, that is, the mold needs to have a structure with meshing serrations and outer ring serrations of the gear body, such as a serration module corresponding to the meshing serration shape. After the gear body is formed, it can be removed from the mold and mounted on the fixed shaft.

[0005] With respect to the above-mentioned related technologies, the inventors believe that the following defects exist: there are uncertain shape errors between the serration module of the injection mold and the matching knurling wheel on the fixed shaft, and the polymer gear body that can have a high degree of matching with the serration module may not necessarily have a high degree of matching with the matching knurling wheel, that is, the matching between the gear body and the fixed shaft is poor, and the circumferential stability and transmission firmness of the two after matching will be negatively affected. Summary of the invention

[0006] In order to improve the above problems, the present application provides a double gear and its production tooling and process.

[0007] In the first aspect, the present application provides a production process for a double gear using the following technical solution:

[0008] A production process for a double gear comprises the following steps in sequence:

[0009] S1: Coaxially sleeve a gear blank with smooth inner and outer walls on the outside of a matching knurled wheel of a fixed shaft;

[0010] S2: performing thermoplastic treatment on the gear blank sleeved on the fixed shaft;

[0011] S3: The gear blank is formed into meshing serrations and cooled to set the shape;

[0012] S4: Perform gear hobbing on the outer wall of the gear blank.

[0013] By adopting the above technical solution, the gear blank is hot-melted onto the mating knurled wheel to achieve its mating installation with the fixed shaft, which is equivalent to the mating knurled wheel being a serrated module. A serrated structure for circumferential limitation is formed in the second gear body based on the mating knurled wheel. The mating state of this structure and the mating knurled wheel can achieve a higher degree of tightness and stability.

[0014] Preferably, in S1, the gear blank and the mating knurling wheel are interference fit.

[0015] By adopting the above technical solution, when the gear blank and the mating knurling wheel are in an interference fit state, the part of the gear blank close to its own inner ring side will produce elastic deformation and internal stress. During the plasticization process of the nylon, the nylon on the inner ring part of the gear blank will flow into the serration gap of the mating knurling wheel, thereby improving the forming efficiency of the meshing serrations.

[0016] In the second aspect, the present application provides a double gear adopting the following technical solution:

[0017] A double gear comprises a fixed shaft, on which a first gear body is coaxially fixedly connected, a second gear body is coaxially sleeved on the fixed shaft and located on one side of the fixed shaft, a matching knurled wheel is coaxially fixedly connected to the fixed shaft, and a wedge-mounted chamfer is provided at the edge of one end of the matching knurled wheel away from the first gear body.

[0018] By adopting the above technical solution, since the gear blank and the mating knurling wheel are interference fit, the presence of the wedge-mounted chamfer provides a hole-expanding force when the gear blank is fitted on the mating knurling wheel, thereby improving the operational smoothness when the gear blank and the mating knurling wheel are mated.

[0019] Preferably, a stop ring groove is provided on the mating knurling wheel.

[0020] By adopting the above technical solution, the material of the inner ring part of the gear blank will enter the stop ring groove at the same time after plasticization, so that a coaxial convex ring structure is formed on one side of the inner ring of the gear blank. This convex ring structure cooperates with the stop ring groove, and cooperates with the knurling wheel and the gear blank to form an axial limit to each other.

[0021] In the third aspect, the present application provides a double gear adopting the following technical solution:

[0022] A production tool for double gears includes a press-fitting die frame, the press-fitting die frame includes a fixed template and an assembly template, the assembly template slides relative to the fixed template, a clamp mechanism is provided between the assembly template and the fixed template, the clamp mechanism is used to temporarily fix the gear blank and the fixed shaft, the fixed shaft is fixed relatively to the fixed template, and the gear blank is fixed relatively to the assembly template.

[0023] By adopting the above technical solution, the assembly template carries the gear blank and moves toward the fixed template that fixes the fixed shaft, so that the gear blank is successfully sleeved outside the fixed shaft, thereby realizing the installation of the two.

[0024] Preferably, the clamp mechanism includes a fixed seat, a sleeve rod and a pushing sleeve, the fixed seat is detachably connected to the fixed template, the pushing sleeve is detachably connected to the assembly template, a placement hole is opened on the fixed seat, the placement hole is for the fixed shaft to be inserted, the pushing sleeve is coaxially sleeved outside the sleeve rod, the placement hole is coaxial with the sleeve rod, the gear blank is coaxially sleeved outside the sleeve rod, and the end face of the pushing sleeve abuts against the gear blank.

[0025] Preferably, a return spring is provided in the propulsion sleeve, one end of the return spring is connected to the propulsion sleeve, and the other end is connected to the sleeve rod.

[0026] By adopting the above technical solution, the fixed shaft is placed in the placement hole. When the assembly template moves the sleeve rod to abut against the end face of the fixed shaft, the push sleeve continues to move relative to the sleeve rod. When the push sleeve abuts against the gear blank, it applies thrust to it, thereby pressing the gear blank onto the matching knurled wheel; when the assembly template returns, the reset spring applies elastic force to reset the push sleeve and the sleeve rod relatively.

[0027] Preferably, a lifting assembly is provided on the sleeve rod and between the end faces of the gear blank and the sleeve rod facing the fixed seat, a clearance groove is provided on the side wall of the sleeve rod, the lifting assembly includes a lifting plate and a lifting spring, the lifting plate is hinged to the groove wall of the clearance groove, one end of the lifting spring is fixedly connected to the groove wall of the clearance groove, and the other end is fixedly connected to the lifting plate, and the hinge axis of the lifting plate is located on the groove wall of the clearance groove close to the assembly template.

[0028] By adopting the above technical solution, the lifting plate forms a spatial barrier to the axial movement of the gear blank, reducing the possibility of the gear blank accidentally detaching from the mounting rod; due to the presence of the lifting spring, when the lifting plate is subjected to thrust, the lifting plate will flip into the clearance groove, at which time the spatial barrier to the gear blank is lost, and the gear blank can move across the lifting plate.

[0029] Preferably, a pulling assembly is also provided on the suit rod, and the pulling assembly includes a control member and a pulling rope. The control member slides relative to the suit rod, one end of the pulling rope is fixedly connected to the side of the lifting plate facing the lifting spring, and the other end is fixedly connected to the control member.

[0030] Preferably, the control member is a control nut, the control nut is slidably connected to the propulsion sleeve, and the control nut is coaxially threadedly connected to the sleeve rod.

[0031] By adopting the above technical solution, the control nut and the set rod are rotated relative to each other, and the positional relationship between the two in the length direction changes. Tension is generated on the pull rope, and the tension acts on the lifting plate to pull the lifting plate into the clearance groove, thereby achieving the purpose of releasing the spatial limitation of the lifting plate on the gear blank under the premise that the lifting plate is not under pressure.

[0032] In summary, the present application includes at least one of the following beneficial technical effects:

[0033] 1. The gear blank is hot-melted onto the matching knurled wheel to achieve matching installation with the fixed shaft, which is equivalent to the matching knurled wheel being a sawtooth module. The second gear body is formed with a sawtooth structure for circumferential limiting based on the matching knurled wheel. The matching state of this structure and the matching knurled wheel can achieve a higher degree of fastening and stability;

[0034] 2. Through the setting of the lifting assembly, when the gear blank is sleeved on the set rod, the lifting plate temporarily supports and limits the gear blank, reducing the possibility of the gear blank accidentally slipping off the set rod. When the sleeve pushes the gear blank, the supporting rod is squeezed into the clearance hole, so that the gear blank can smoothly cross the lifting plate and reach the fixed shaft to achieve assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the double gears in the embodiment of the present application.

[0036] Figure 2 It is a schematic diagram of the structure of the production tooling for double gears in the embodiment of the present application.

[0037] Figure 3 It is a schematic diagram of the overall structure of the clamp assembly used to illustrate the embodiment of the present application.

[0038] Figure 4 yes Figure 3 A partial enlarged view of part A in the middle.

[0039] Figure 5 It is a structural schematic diagram used to reflect the lifting component and the pulling component in the embodiment of the present application.

[0040] Explanation of the reference numerals: 1. fixed shaft; 11. first gear body; 12. matching knurled wheel; 121. stop ring groove; 122. wedge-mounted chamfer; 13. second gear body; 131. meshing serrations; 14. gear blank; 2. press-fit die frame; 21. fixed template; 22. assembly template; 23. mounting bolts; 24. control guide sleeve; 25. control guide column; 26. control spring; 3. clamp mechanism; 31. fixed seat; 311. placement hole; 32. thrust sleeve; 321. guide groove; 322. reset spring; 33. set rod; 331. connecting partition; 332. clearance groove; 34. lifting assembly; 341. lifting plate; 342. lifting spring; 35. pull assembly; 351. control nut; 352. guide block; 353. pull rope. DETAILED DESCRIPTION

[0041] The following is combined with Figure 1-5 This application is described in further detail.

[0042] In a first aspect, the present application discloses a double gear, such as Figure 1 As shown, it includes a fixed shaft 1, on which a first gear body 11 is coaxially integrally formed, both of which are made of metal; a matching knurling wheel 12 is also coaxially integrally formed on the fixed shaft 1, and a second gear body 13 is mounted on the fixed shaft 1 and located at the matching knurling wheel 12. The second gear body 13 is made of nylon, and an engaging serration 131 is integrally formed on the inner ring surface of the second gear. The engaging serration 131 will mesh with the matching knurling wheel 12, so as to achieve circumferential positioning of the second gear body 13 by the fixed shaft 1. In this embodiment, the first gear body 11 and the second gear body 13 are both helical gears.

[0043] In a second aspect, the present application discloses a production process for a double gear. Figure 1 As shown, in order to improve the degree of tightness between the second gear body 13 and the fixed shaft 1, the forming of the meshing serrations 131 inside the second gear body 13 will directly use the matching knurling wheel 12 as a template, that is, the second gear does not have the meshing serrations 131 before being sleeved on the fixed shaft 1, and it is a gear blank 14 with smooth inner and outer wall surfaces.

[0044] The production process of double gears includes the following steps in sequence:

[0045] S1: Coaxially sleeve the gear blank 14 on the outside of the matching knurling wheel 12 of the fixed shaft 1;

[0046] S2: A high-frequency heating machine is used to perform thermoplastic treatment on the gear blank 14 sleeved on the fixed shaft 1, so that the nylon in the inner ring of the gear blank 14 is plasticized and flows into the sawtooth gap of the matching knurling wheel 12;

[0047] S3: the gear blank 14 is formed into meshing serrations 131 and cooled to finalize;

[0048] S4: The outer wall of the gear blank 14 is subjected to gear hobbing processing using a gear hobbing machine.

[0049] like Figure 1 As shown, the inner diameter of the gear blank 14 is smaller than the major diameter of the mating knurling wheel 12, that is, the mating state of the gear blank 14 and the mating knurling wheel 12 is an interference fit. The gear blank 14 needs to be inserted into the fixed shaft 1 from the end of the mating knurling wheel 12 away from the first gear body 11, so a wedge-mounted chamfer 122 is provided at the end face edge of the end of the mating knurling wheel 12 away from the first gear body 11, and the wedge-mounted chamfer 122 will provide a smooth hole expansion transition for the fitting process of the gear blank 14. A stop ring groove 121 is provided in the middle of the mating knurling wheel 12 in the length direction. In S2, the nylon of the inner ring part of the gear blank 14 will also enter the stop ring groove 121 after plasticization, so that a coaxial convex ring is formed on one side of the inner ring of the gear blank 14. This convex ring cooperates with the stop ring groove 121, and the mating knurling wheel 12 and the gear blank 14 form a mutual limit in the axial direction.

[0050] The implementation principle of a double gear and its production process in the embodiment of the present application is as follows:

[0051] When the gear blank 14 and the mating knurling wheel 12 are in an interference fit state, the portion of the gear blank 14 close to its own inner ring side will produce elastic deformation and internal stress. During the plasticization of the nylon, the nylon in the inner ring portion of the gear blank 14 will flow into the serrated gap of the mating knurling wheel 12. After cooling, the nylon entering the serrated gap of the mating knurling wheel 12 is formed into the meshing serrations 131. Since the meshing serrations 131 are formed with the mating knurling wheel 12 as a mold, combined with the shrinkage of the material itself, the degree of fit between the two after forming is highly stable.

[0052] In a third aspect, the present application discloses a production tool for a double gear, which is used to press-fit the gear blank 14 onto the mating knurling wheel 12, such as Figure 2 As shown, it includes a press-fitting die frame 2, which includes a fixed template 21 and an assembly template 22, and the surfaces of the two are parallel to each other. A control guide sleeve 24 is fixedly connected to the fixed template 21, and a control guide column 25 is fixedly connected to the assembly template 22. The control guide column 25 is inserted into the control guide sleeve 24, and a control spring 26 is coaxially arranged outside the control guide column 25. One end of the control spring 26 is fixedly connected to the assembly template 22, and the other end is fixedly connected to the end surface of the control guide sleeve 24 facing the assembly template 22. The assembly template 22 slides relative to the fixed template 21 through the cooperation of the control guide column 25 and the control guide sleeve 24, and the sliding direction is perpendicular to the surface of the fixed template 21.

[0053] like Figure 2 and Figure 3As shown, a clamp mechanism 3 is provided on the press-fit die frame 2 and between the fixed template 21 and the assembly template 22. The clamp mechanism 3 is used to clamp and fix the fixed shaft 1 and the gear blank 14 respectively. The clamp mechanism 3 includes a fixing seat 31, a set rod 33 and a pushing sleeve 32. The fixing template 21 and the assembly template 22 are both fixedly connected with mounting bolts 23 on the opposite plate surfaces. The mounting bolts 23 on the fixing template 21 are coaxial with the mounting bolts 23 on the assembly template 22, and their length direction is perpendicular to the plate surface of the fixing template 21. The fixing seat 31 is used to place the fixing shaft 1 on the fixing template 21. The fixing seat 31 is threadedly connected with the mounting bolts 23 on the fixing template 21. A placement hole 311 is provided on the side of the fixing seat 31 away from the fixing template 21. The placement hole 311 is coaxial with the mounting bolt 23 and is used for inserting and placing the fixing shaft 1. After the fixing shaft 1 is inserted into the placement hole 311, the knurling wheel 12 is located at the end of the first gear body 11 away from the fixing template 21.

[0054] like Figure 4 and Figure 5 As shown, one end of the push sleeve 32 is closed, and the other end is open. The open end of the push sleeve 32 is sleeved outside the set rod 33, and the closed end faces the assembly template 22 and is coaxially threaded with the mounting bolt 23 located on the assembly template 22. At this time, the push sleeve 32, the set rod 33 and the fixed shaft 1 are coaxial with each other. The inside of the set rod 33 is a cavity, that is, the set rod 33 is a tubular object, and a connecting partition 331 is integrally formed inside it; a reset spring 322 is coaxially arranged inside the push sleeve 32, one end of the reset spring 322 is rotatably connected to the closed end of the push sleeve 32, and the other end extends into the set rod 33 and is fixedly connected to the connecting partition 331. The outer diameter of the set rod 33 is the same as the minor diameter of the matching knurling wheel 12, and is the same as the nominal size of the inner diameter of the gear blank 14. The inner diameter of the set rod 33 is the same as the radial size of the fixed shaft 1. The gear blank 14 is sleeved outside the set rod 33, and the thrust sleeve 32 and the set rod 33 are moved relative to each other. The end face of the thrust sleeve 32 will abut the gear blank 14 to push it toward the matching knurling wheel 12.

[0055] like Figure 3 and Figure 5As shown, in order to reduce the possibility of accidental slipping of the gear blank 14 before the set rod 33 contacts the mating knurling wheel 12, a lifting assembly 34 and a pulling assembly 35 are provided on the set rod 33. The lifting assembly 34 includes a lifting plate 341 and a lifting spring 342. The lifting plate 341 is hinged to the set rod 33. A clearance groove 332 is opened on the side wall of the set rod 33. In this embodiment, the number of the clearance grooves 332 and the number of the lifting plates 341 are both three, and the three clearance grooves 332 are arranged in a circular array with the axis of the set rod 33 as the center; a single clearance groove 332 is provided for a lifting plate 341 to be placed, and the lifting plate 341 is hinged to the groove wall of the clearance groove 332 close to the assembly template 22, and the rotation plane of the lifting plate 341 is parallel to the axis of the set rod 33. One end of the lifting spring 342 is fixedly connected to the bottom of the clearance groove 332, and the other end is fixedly connected to the plate surface of the lifting plate 341. In a natural state, the lifting plate 341 extends out of the clearance groove 332, and the edge of the lifting plate 341 away from its own hinge point is inclined toward the fixed template 21. At this time, the lifting plate 341 forms a spatial barrier for the gear blank 14 to slip off the sleeve rod 33; and if the thrust sleeve 32 applies a thrust to the gear blank 14, the gear blank 14 squeezes the lifting plate 341 to flip it into the clearance groove 332, and the gear blank 14 can move toward the mating knurled wheel 12.

[0056] like Figure 5 As shown, the pulling assembly 35 is used to remove the space obstruction of the lifting assembly 34 during the process of sleeve the gear blank 14 on the sleeve rod 33; the pulling assembly 35 includes a control member and a pulling rope 353, the number of the pulling rope 353 is consistent with the number of the lifting plates 341, and the control member is a control nut 351 coaxially threadedly connected to the end of the sleeve rod 33 away from the fixed template 21. The control nut 351 is slidably connected to the propulsion sleeve 32, and a guide groove 321 is provided on the inner side wall of the propulsion sleeve 32 along its own length direction. A guide block 352 is integrally formed on the side wall of the control nut 351, and the guide block 352 is located in the guide groove 321, that is, the control nut 351 cannot rotate in the propulsion sleeve 32, so when a torque is applied to the sleeve rod 33, the thread pair between the sleeve rod 33 and the control nut 351 will move. The pulling rope 353 corresponds to the lifting plate 341 one by one. One end of a single pulling rope 353 is fixedly connected to the plate surface of the lifting plate 341 facing the lifting spring 342, and the other end is located in the set rod 33, passes through the connecting partition 331 and is fixedly connected to the control nut 351; when the set rod 33 is rotated to move it away from the control nut 351, the pulling rope 353 will tend to be stretched and generate a pulling force on the lifting plate 341, and the lifting plate 341 will be pulled into the yield groove 332. At this time, the lifting plate 341 will no longer have a spatial influence on the movement of the gear blank 14 along the set rod 33.

[0057] The implementation principle of a production tool for a double gear in the embodiment of the present application is as follows:

[0058] Now, according to the size of the fixed shaft 1 and the second gear body 13, the corresponding fixing seat 31 and the pushing sleeve 32 are selected and installed on the fixed template 21 and the assembly template 22 respectively. The fixed shaft 1 is placed on the fixing seat 31, and the gear blank 14 is sleeved on the sleeve rod 33. The press-fitting die frame 2 is then set up. The press-fitting die frame 2 is placed on a pressure device such as a hydraulic press, and the pressure device is started. The assembly template 22 moves. When the end face of the sleeve rod 33 abuts against the end face of the matching knurling wheel 12, the sleeve rod 33 cannot continue to move, and the pushing sleeve 32 continues to move and pushes the gear blank 14 toward the matching knurling wheel 12. When the matching knurling wheel 12 is completely sleeved by the gear blank 14, the combined assembly of the gear blank 14 and the fixed shaft 1 is completed, the end face of the pushing sleeve 32 is flush with the end face of the sleeve rod 33, and the pressure device stops pressurizing.

[0059] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A production process for double gears, Features: The steps are as follows: S1: Coaxially sleeve a gear blank (14) with smooth inner and outer side walls on the outside of a matching knurled wheel (12) of a fixed shaft (1); S2: performing a thermoplastic treatment on the gear blank (14) sleeved on the fixed shaft (1); S3: The gear blank (14) is formed into meshing serrations (131) and cooled to finalize the shape; S4: performing gear hobbing on the outer wall of the gear blank (14); The production tooling used for sleeve-mounting the gear blank (14) outside the mating knurling wheel (12) comprises a press-mounting die frame (2), the press-mounting die frame (2) comprises a fixed template (21) and an assembly template (22), the assembly template (22) slides relative to the fixed template (21), a clamping mechanism (3) is provided between the assembly template (22) and the fixed template (21), the clamping mechanism (3) is used for temporarily fixing the gear blank (14) and the fixed shaft (1), the fixed shaft (1) and the fixed template (21) are fixed relative to each other, and the gear blank (14) and the assembly template (22) are fixed relative to each other; The clamp mechanism (3) comprises a fixed seat (31), a sleeve rod (33) and a propulsion sleeve (32); the fixed seat (31) is detachably connected to the fixed template (21); the propulsion sleeve (32) is detachably connected to the assembly template (22); a placement hole (311) is provided on the fixed seat (31); the placement hole (311) is for the fixed shaft (1) to be inserted; the propulsion sleeve (32) is coaxially sleeved outside the sleeve rod (33); the placement hole (311) is coaxial with the sleeve rod (33); the gear blank (14) is coaxially sleeved outside the sleeve rod (33); and the end face of the propulsion sleeve (32) abuts against the gear blank (14); A lifting assembly (34) is provided on the sleeve rod (33) and between the gear blank (14) and the end surface of the sleeve rod (33) facing the fixed seat (31); a clearance groove (332) is provided on the side wall of the sleeve rod (33); the lifting assembly (34) comprises a lifting plate (341) and a lifting spring (342); the lifting plate (341) is hinged to the groove wall of the clearance groove (332); one end of the lifting spring (342) is fixedly connected to the groove wall of the clearance groove (332), and the other end is fixedly connected to the lifting plate (341); the hinge axis of the lifting plate (341) is located on the groove wall of the clearance groove (332) close to the assembly template (22); The set rod (33) is also provided with a pulling assembly (35), and the pulling assembly (35) comprises a control member and a pulling rope (353), the control member and the set rod (33) slide relative to each other, one end of the pulling rope (353) is fixedly connected to the side of the lifting plate (341) facing the lifting spring (342), and the other end is fixedly connected to the control member; The control member is a control nut (351), the control nut (351) is slidably connected to the propulsion sleeve (32), and the control nut (351) is coaxially threadedly connected to the sleeve rod (33).

2. A production process for a double gear according to claim 1, Features: A return spring (322) is arranged inside the propulsion sleeve (32), one end of the return spring (322) is connected to the propulsion sleeve (32), and the other end is connected to the sleeve rod (33).

3. A production process for a double gear according to claim 1, Features: In S1, the gear blank (14) and the matching knurling wheel (12) are in interference fit.

4. A double gear produced by the double gear production process according to claim 1, comprising a fixed shaft (1), a first gear body (11) being coaxially fixedly connected to the fixed shaft (1), a second gear body (13) being coaxially sleeved on the fixed shaft (1) and located on one side of the fixed shaft (1), a matching knurling wheel (12) being coaxially fixedly connected to the fixed shaft (1), Features: A wedge-mounted chamfer (122) is provided at the edge of one end of the matching knurled wheel (12) away from the first gear body (11).

5. A double gear according to claim 4, Features: The matching knurling wheel (12) is provided with a stop ring groove (121).

Images