An outer spline bushing with a positioning platform and a processing method

Abstract

The present application belongs to the technical field of mechanical processing, and particularly relates to a kind of external spline bushings with positioning table and processing method, including split design external spline bushings with positioning table as spline shaft and bushing base, the two are respectively processed to preset size, and respectively recess is opened on spline shaft and bushing base, anti-rotation pin is bonded in the recess of spline shaft lower end shaft;And the lower end surface of bushing base is heated;In the hot state of bushing base, the spline shaft bonded with anti-rotation pin is pressed into the inner hole of bushing base along the axial direction, after the assembled spline shaft and bushing base are cooled, bonding is used in the joint with glue, and external spline bushing with positioning table is obtained. The comprehensive application of split design and hot pressing process can precisely process external spline by modifying grinding wheel and using gear grinding process, and detect tooth profile using conventional measurement method, without the need to manufacture special gauge. The technical problems of high manufacturing cost, long cycle and gear grinding process profile interference in the prior art are solved.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically relating to an external spline bushing with a positioning table and a machining method thereof. Background Technology

[0002] The spline bushing described in this application ( Figure 1 Made of 30CrMnSiA material with a hardness of HRC 35-40, this bushing is used to connect the splined surface of the product and related components of the fixture, and withstands a certain torsional force during operation. The bushing has a thin-walled structure, with a non-through triangular toothed external spline at the upper end and a cylindrical stop boss with a diameter larger than the spline surface at the lower end. The inner hole at the upper end of the bushing is round, and the inner hole at the lower end is square. The spline has coaxial accuracy requirements relative to the lower outer circle and the square hole. The difficulty and key point in machining this type of part lies in its spline surface.

[0003] For spline tooth surface bushings with medium to low hardness, the most common technical solution is integral manufacturing, in which the spline tooth profile is machined using a gear shaping process. However, when using the gear shaping process, it is necessary to use special gear shaping tools and special tooling such as spline ring gauges and calibration gauges for inspection. This has disadvantages such as high manufacturing costs and long development cycles for the tooling. Especially in single-piece and small-batch production, the manufacturing cost and cycle of the tooling are far greater than the product itself. Some precision spline profiles are also machined using a gear grinding process. When using the gear grinding process, the part needs to meet the requirement that the minimum diameter of the spline profile is greater than the maximum outer diameter of the other profiles, or a sufficient amount of clearance is reserved at the connection between the spline profile and another profile to avoid interference problems during spline grinding.

[0004] Publication No. CN 107641684A discloses a method for machining spline bushings including gear shaping, and its third step, "finishing the annealed workpiece and inserting splines," describes the machining method for the spline tooth surface. Publication No. CN103447774A discloses a method for extruding splines (see third step). Publication No. CN107984169A discloses a process method for machining splines using a mold. These technologies have addressed the machining quality and efficiency issues of spline bushing parts to varying degrees, but none have solved the problems of development cycle and cost of dedicated tooling or grinding interference, thus limiting their reference value to the application. To address the excessively high manufacturing cost and long cycle time, as well as surface interference in the grinding process, that exist with using gear shaping for these parts, a new process method is needed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for machining an external spline bushing with a positioning stage, so as to solve the technical problems of excessively high manufacturing cost, excessively long cycle, and surface interference of the grinding process in the prior art when machining an external spline bushing with a positioning stage using a gear shaping process.

[0006] To achieve the above object, the present application adopts the following technical solutions to achieve the above object:

[0007] The first invention is a processing method of a positioning platform outer spline bushing, comprising the following steps:

[0008] S1: the corresponding to-be-processed parts of the spline shaft and the bushing base are respectively processed to a preset size, and grooves are respectively formed in the lower end shaft of the spline shaft and the inner hole of the bushing base;

[0009] S2: an anti-rotation pin is bonded in the groove of the lower end shaft of the spline shaft; and the lower end surface of the bushing base is heated;

[0010] S3: in the heated state of the bushing base, the spline shaft with the bonded anti-rotation pin is axially pressed into the inner hole of the bushing base, wherein the anti-rotation pin on the spline shaft is matched with the groove of the bushing base;

[0011] S4: after the assembled spline shaft and bushing base are cooled, bonding is performed at the joint using glue, and the positioning platform outer spline bushing is obtained.

[0012] Preferably, the spline shaft comprises a spline profile, an empty cutting segment and an assembly shaft, the spline profile, the empty cutting segment and the assembly shaft are sequentially arranged from top to bottom, and the assembly shaft is connected with the bushing base.

[0013] Preferably, the bushing base has a stepped outer circle and three inner holes, wherein the first inner hole is used for matching with the spline shaft, the second inner hole is empty, and the square hole is a square hole; the first inner hole, the second inner hole and the square hole are sequentially arranged from top to bottom.

[0014] Preferably, the first inner hole and the second inner hole of the bushing base and the cylindricity and coaxiality of the stepped outer circle are not greater than 0.01 mm.

[0015] Preferably, the spline shaft comprises a spline profile, an empty cutting segment and an assembly shaft, and the S1 specifically comprises:

[0016] S101: the spline shaft and the bushing base are turned to a preset outer diameter, center holes are processed on both end surfaces of the spline shaft, a wire hole is processed at the square hole of the bushing base, and then quenching and aging heat treatment is performed;

[0017] S102: the first inner hole and the second inner hole of the bushing base and the outer circle are ground to a specified size, then the square hole is processed by wire cutting based on the ground outer circle, and the coaxiality is not greater than 0.01 mm;

[0018] S103: the spline profile of the spline shaft is ground to a specified size, the assembly shaft of the spline shaft is ground to an interference fit with the first inner hole of the bushing base; then the outer circle end surface is ground, and the root is cleaned;

[0019] S104: respectively processing grooves on the outer wall of the assembly shaft of the spline shaft and the inner wall of the first inner hole of the bushing base.

[0020] Preferably, the spline shaft and the bushing base are interference fit, and the interference is not greater than 0.005mm.

[0021] Preferably, in S2, the heating temperature is 500-550℃, and the heating time is 4-5min.

[0022] Preferably, the groove depth in S1 is 0.1-0.2mm.

[0023] Preferably, in S2, the anti-rotation pin size is matched with the groove, so that the groove can completely contain the maximum entity of the anti-rotation pin.

[0024] The second application is an external spline bushing with a positioning platform, which is made by the above-mentioned processing method.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] 1) Thanks to the improved structure and the comprehensive application of the hot pressing process, the triangular external spline can be precisely machined by modifying the grinding wheel and using the gear grinding process, so as to obtain high machining precision; the tooth profile can be detected by using general optical measurement methods, without the need to manufacture special gauges. After the grinding wheel is modified, it can still be used, and the overall manufacturing cost of this method is much lower than the development cost of the gear shaping cutter.

[0027] 2) The manufacturing cycle is greatly shortened due to the reduction of the development link of special tooling.

[0028] 3) The hot assembly process is commonly used in the installation of the tool holder of the numerical control machine tool or the manufacturing of the mold product, and the technical scheme of combining the hot pressing process and the adhesive process with the anti-rotation pin is rarely reported. The technical scheme described in the application makes the spline bushing connection firm, reliable in use, and capable of transmitting the designed torque.

[0029] 4) The heating temperature of the bushing base is 500-550℃, when the heating temperature is lower than 500℃, the size expansion of the bushing is small, the shaft pin pressure is large, and the cracking waste rate is 30%; when the heating temperature of the bushing is higher than 550℃, it exceeds the tempering temperature of the 30CrMnSiA material, and the cracking rate of the bushing after pressure fitting is 20%. The temperature adopted in the application is sufficient to ensure the application of the hot assembly process in thin-walled parts. By using the hot assembly technology combined with the anti-rotation pin, the bushing is firmly combined and has the anti-torsion ability to meet the use requirements without the problem of thin-walled cracking caused by cold assembly. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0031] Figure 1 The schematic diagram of the external spline bush structure in the prior art;

[0032] Figure 2 The schematic diagram of the spline shaft structure of the present application;

[0033] Figure 3 The schematic diagram of the bush base structure of the present application;

[0034] Figure 4 The schematic diagram of the recess structure of the present application; wherein (a) is the assembly shaft sectional view; (b) is the bush base A-A surface sectional view;

[0035] Figure 5 The schematic diagram of the external spline bush structure with positioning platform of the present application.

[0036] Wherein: 1-spline shaft; 101-spline profile; 102-empty cutting section; 103-assembly shaft; 2-bush base; 201-step outer circle; 202-first inner hole; 203-second inner hole; 204-square hole; A-glue bonding position; 3-external spline bush with positioning platform. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0039] It should be noted that: similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0040] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicate the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0041] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0042] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, if the terms "set", "mount", "connected", "connected" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] The present application will be described in further detail below in conjunction with the accompanying drawings:

[0044] To solve the problems of manufacturing cost, cycle and interference caused by the prior art, the present application proposes a machining process taking hot assembly as the core technology. The present application is first to split the bushing into a split structure that does not interfere with the part structure characteristics; second, to use hot assembly technology combined with anti-rotation pins to make the bushing firmly combined and have the torsional resistance required for use without the thin-walled rupture problem that may occur during cold assembly. Further, the present application requires the hot assembly process parameters for the bushing made of 30CrMnSiA material, and the specific content is:

[0045] Referring to Figure 5 The present application discloses a machining method for a bushing with an external spline and a positioning table, comprising the following steps:

[0046] S1: Machining the corresponding workpieces of the spline shaft 1 and the bushing base 2 to a predetermined size, and respectively forming grooves in the lower end shaft of the spline shaft 1 and the inner hole of the bushing base 2;

[0047] S2: bonding an anti-rotation pin in the groove of the lower end shaft of the spline shaft 1; and heating the lower end surface of the bushing base 2;

[0048] S3: In the hot state of the bush base 2, the spline shaft 1 with the anti-rotation pin is pressed into the inner hole of the bush base 2 in the axial direction, wherein the anti-rotation pin on the spline shaft 1 is matched with the groove of the bush base 2.

[0049] S4: After the assembled spline shaft 1 and the bush base 2 are cooled, the joint is bonded using glue, and a positioning table outer spline bushing is obtained.

[0050] The application innovatively splits the positioning table outer spline bushing into a spline shaft 1 and a bush base 2, adopts a split structure to avoid gear interference, and adopts a gear grinding process to avoid the development of special tools and gauges, thereby solving the technical problem of high manufacturing cost. The hot assembly (hot pressing) process avoids the damage to the thin-walled part of the bushing, which is mainly manifested in cracks visible to the naked eye or micro-cracks invisible to the naked eye. At the same time, the anti-rotation pin allows the bushing to bear torque, making the spline bushing connection firm, reliable, and capable of transmitting the required torque. In summary, the application benefits from the comprehensive application of the improved structure and hot pressing process. The triangular outer spline can be precisely machined using the gear grinding process after the grinding wheel is modified, thereby obtaining high machining precision. The tooth profile can be detected using general optical measurement methods without the need to manufacture special gauges. The grinding wheel can still be used after modification, and the overall manufacturing cost of this method is much lower than the development cost of the gear shaping cutter.

[0051] In some embodiments, referring to Figure 2 , the spline shaft 1 comprises a spline profile 101, a blanking section 102, and an assembly shaft 103; the spline profile 101, the blanking section 102, and the assembly shaft 103 are sequentially arranged from top to bottom, and the assembly shaft 103 is connected with the bush base 2. The spline shaft 1 is designed in a split structure, the spline profile 101 is precisely machined using the gear grinding process to obtain high machining precision without affecting the positioning table, and the machined spline profile 101 can be detected using general optical measurement methods without the need to manufacture special gauges.

[0052] In some embodiments, referring to Figure 3 , the bush base 2 has a stepped outer circle 201 and three inner holes, wherein the first inner hole 202 is matched with the spline shaft 1, the second inner hole 203 is blanked, and the square hole 204 is a square hole; the first inner hole 202, the second inner hole 203, and the square hole 204 are sequentially arranged from top to bottom. The assembly shaft 103 is assembled with the first inner hole 202 with an interference, and the interference is not greater than 0.005 mm.

[0053] In some embodiments, the first inner hole 202 and the second inner hole 203 of the bush base 2 and the cylindricity and coaxiality of the stepped outer circle 201 are not greater than 0.01 mm.

[0054] In some embodiments, the spline shaft 1 comprises a spline profile 101, a hollow section 102, and an assembly shaft 103, and the S1 specifically comprises:

[0055] S101: Turn the spline shaft 1 and the bushing base 2 to a preset outer diameter, process a center hole at both ends of the spline shaft 1, and process a wire hole at the square hole 204 of the bushing base 2, and then perform quenching and aging heat treatment;

[0056] S102: Grind the first inner hole 202 and the second inner hole 203 of the bushing base 2 to a specified size, and then perform wire cutting processing on the square hole 204 with the ground outer circle as a reference, and the coaxiality is not greater than 0.01 mm;

[0057] S103: Grind the spline profile 101 of the spline shaft 1 to a specified size, grind the assembly shaft 103 of the spline shaft 1 to an interference fit with the first inner hole 202 of the bushing base 2, and then grind the outer circle end face and clean the root;

[0058] S104: Process a groove on the outer wall of the assembly shaft 103 of the spline shaft 1 and the inner wall of the first inner hole 202 of the bushing base 2, respectively.

[0059] In some embodiments, the heating temperature in S2 is 500-550°C, and the heating time is 4-5 min. The hot assembly process is commonly used in numerical control machine tool handle installation or mold product manufacturing. The combination of this technology with grinding and other cold processes is rarely reported in the technical scheme of precision clamps. The technical scheme described in this application uses an anti-rotation pin combined with a hot pressing process and a gluing process, so that the spline bushing connection is firm, reliable to use, can transmit the designed torque, and the bushing base heating temperature is 500-550°C. When the heating temperature is lower than 500°C, the bushing size expands slightly, the shaft pin pressure is larger, and the cracking waste rate is 30%. When the bushing heating temperature is higher than 550°C, it exceeds the tempering temperature of 30CrMnSiA material, and the bushing cracking rate after assembly is 20%. The temperature used in this application is sufficient to ensure the application of the hot assembly process in thin-walled parts.

[0060] In some embodiments, the groove depth in S1 is 0.1-0.2 mm.

[0061] In some embodiments, the anti-rotation pin size in S2 is matched with the groove, so that the groove can completely contain the maximum entity of the anti-rotation pin. The use of the hot assembly technology combined with the anti-rotation pin makes the bushing firmly combined and has the anti-torsion ability to meet the use requirements without the thin-walled cracking problem caused by cold assembly.

[0062]

Embodiment 1

[0063] 1) Redesign the part as Figure 2The split structure is shown. The upper end of the spline shaft 1 is the general spline surface 101, the middle is the hollow section 102, and the lower end is the assembly shaft 103; the bushing base 2 has a stepped outer circle 201 and three sections of inner hole, wherein the first inner hole 202 is used to mate with the spline shaft 1, the second inner hole 203 is a hollow section, and the lower end is a square hole 204.

[0064] 2) Turn the splined shaft 1 and bushing base 2 to the specified dimensions, machine the center holes on both ends of the splined shaft 1, and machine the threading holes at the square hole 204 of the bushing base 2. Then, perform quenching and aging heat treatment.

[0065] 3) Grind the first inner hole 202 and the outer circle 201 of the step to the specified size of the bushing base 2, ensuring that the cylindricity and coaxiality are not greater than 0.01mm. Then, take the ground outer circle 201 as the reference and perform wire cutting on its square hole 204 to ensure the size and coaxiality.

[0066] 4) Grind the spline profile 101 of the spline shaft 1 to the specified dimensions, and grind the assembly shaft 103 at the lower end of the spline shaft 1 to make an interference fit with the first inner hole 202 of the bushing base 2, with an interference amount not greater than 0.005mm; then grind the outer end face and clean the root.

[0067] 5) Grooves are machined on the assembly shaft 103 of the splined shaft 1 and at the first inner hole 202 of the bushing base 2, respectively, wherein the groove depth is 0.1mm, and the assembly shaft 103 is an Ra0.4 shaft, see Figure 4 .

[0068] 6) Use glue to firmly bond the anti-rotation pin to the R0.5 groove of the spline shaft 1, and clean up any excess glue. The anti-rotation pin is a cylindrical pin.

[0069] 7) Use a heating platform to heat the lower end face of the bushing base 2 at a temperature of 500℃ for 5 minutes.

[0070] 8) When the bushing base 2 is hot, slowly press the spline shaft 1 with the cylindrical pin attached into the inner hole of the bushing base 2 along the axial direction, and align the protruding cylindrical pin of the spline shaft 1 with the groove of the bushing base 2.

[0071] 9) After the splined shaft 1 and bushing base 2 have cooled, use glue to bond the splined shaft 1 and bushing base 2 together. See section A for glue bonding. Figure 5 .

[0072]

Example 2

[0073] 1) Redesign the parts as Figure 5 The shown is a split structure. See also... Figure 2 The upper end of the spline shaft 1 is the spline profile 101 of the general drawing, the middle is the empty tool section 102, and the lower end is the assembly shaft 103; see alsoFigure 3 The bush base 2 has a stepped outer circle 201 and three-section inner hole, wherein the first inner hole 202 is used for matching with the spline shaft 1, the second inner hole 203 is empty, and the lower end is a square hole 204.

[0074] 2) Turn the spline shaft 1 and the bush base 2 to the specified size, process the center hole on both ends of the spline shaft 1, and process the wire hole at the square hole 204 of the bush base 2. Then, quenching and aging heat treatment is carried out.

[0075] 3) Grind the first inner hole 202 and the stepped outer circle 201 of the bush base 2 to the specified size, and ensure that the cylindricity and coaxiality are not greater than 0.01 mm. Then, line cutting is carried out on the square hole 204 of the bush base 2 based on the ground stepped outer circle 201, and the size and coaxiality are ensured.

[0076] 4) Grind the spline profile 101 of the spline shaft 1 to the specified size, grind the assembly shaft 103 at the lower end of the spline shaft 1 to have an interference fit with the first inner hole 202 of the bush base 2, and the interference amount is not greater than 0.005 mm; then grind the outer circle end face and clean the root.

[0077] 5) Process grooves on the assembly shaft 103 of the spline shaft 1 and the first inner hole 202 of the bush base 2 respectively, wherein the groove depth is 0.2 mm, as shown in Figure 4 .

[0078] 6) Use glue to firmly bond the anti-rotation pin with the R0.5 groove of the spline shaft 1, clean the excess glue, and the anti-rotation pin is a cylindrical pin.

[0079] 7) Use a heating platform to heat the lower end face of the bush base 2, the temperature is 550℃, and the time is 4 min.

[0080] 8) In the hot state of the bush base 2, slowly press the spline shaft 1 with the cylindrical pin into the inner hole of the bush base 2 along the axial direction, and align the cylindrical pin protruding from the spline shaft 1 with the groove of the bush base 2.

[0081] 9) After the spline shaft 1 and the bush base 2 are cooled, use glue to bond the combination of the spline shaft 1 and the bush base 2, and the glue bonding position A is shown in Figure 5 .

[0082]

Example 3

[0083] 1) Redesign the parts into a split structure as shown in Figure 5 , wherein, referring to Figure 2 , the upper end of the spline shaft 1 is the overall spline profile 101, the middle is an empty section 102, and the lower end is an assembly shaft 103; referring to Figure 3, the bushing base 2 has a stepped outer circle 201 and three-section inner hole, wherein the first inner hole 202 is matched with the spline shaft 1, the second inner hole 203 is empty, and the lower end is a square hole 204.

[0084] 2) Turn the spline shaft 1 and the bushing base 2 to the specified size, and process the center hole on both ends of the spline shaft 1 and the wire hole at the square hole 204 of the bushing base 2. Then, quenching and aging heat treatment is carried out.

[0085] 3) Grind the first inner hole 202 and the stepped outer circle 201 of the bushing base 2 to the specified size, and ensure that the cylindricity and coaxiality are not greater than 0.01 mm. Then, line cutting is carried out on the square hole 204 of the bushing base 2 based on the ground stepped outer circle 201, and the size and coaxiality are ensured.

[0086] 4) Grind the spline profile 101 of the spline shaft 1 to the specified size, and grind the assembly shaft 103 at the lower end of the spline shaft 1 to an interference fit with the first inner hole 202 of the bushing base 2, with an interference of not greater than 0.005 mm; then grind the outer circle end face and clean the root.

[0087] 5) Process grooves on the assembly shaft 103 of the spline shaft 1 and the first inner hole 202 of the bushing base 2 respectively, wherein the groove depth is 0.2 mm, as shown in Figure 4 .

[0088] 6) Use glue to firmly bond the anti-rotation pin with the R0.5 groove of the spline shaft 1, and clean the excess glue. The anti-rotation pin is a cylindrical pin.

[0089] 7) Use a heating platform to heat the lower end face of the bushing base 2 to a temperature of 520°C for 5 minutes.

[0090] 8) In the hot state of the bushing base 2, slowly press the spline shaft 1 with the cylindrical pin bonded to it into the inner hole of the bushing base 2 along the axial direction, and align the protruding cylindrical pin of the spline shaft 1 with the groove of the bushing base 2.

[0091] 9) After the spline shaft 1 and the bushing base 2 cool down, use glue to bond the combination of the spline shaft 1 and the bushing base 2, and the glue bonding position A is shown in Figure 5 .

[0092] In particular, all the corners not marked in the figure are processed according to C0.5.

[0093] Adopting split structure avoids gear grinding interference, the difficulty lies in structure segmentation. The application innovatively designs the external spline bushing with positioning table as split structure, which is divided into spline shaft 1 and bushing base 2. The spline shaft 1 adopts gear grinding process to avoid developing special tools and measuring tools. The spline shaft 1 and the bushing base 2 are assembled by hot assembly (hot pressing) process to avoid damage to the thin wall part of the bushing (mainly reflected in the cracks visible to the naked eye or micro cracks invisible to the naked eye) by cold assembly. The difficulty lies in the control of heating temperature and time, and attention should be paid to slow axial pressing. The anti-rotation pin combined with hot pressing process and gluing process makes the spline bushing connection firm, reliable and capable of transmitting the designed torque. The heating temperature of the bushing base is 500-550℃. When the heating temperature is lower than 500℃, the size expansion of the bushing is small, the shaft pin fitting pressure is large, and the cracking waste rate is 30%. When the heating temperature of the bushing is higher than 550℃, it exceeds the tempering temperature of 30CrMnSiA material, and the cracking rate of the bushing after fitting is 20%. The temperature adopted in the application is sufficient to ensure the application of hot assembly process in thin-walled parts.

[0094] The application also discloses a spline bushing with a positioning table and external spline.

[0095] The above is only the preferred embodiment of the application and is not used to limit the application. The application can have various changes and variations for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method of machining a belt positioning station external spline bushing, characterized by, The method comprises the following steps: S1: the corresponding parts to be machined of the spline shaft (1) and the bushing base (2) are machined to a preset size, and grooves are formed in the lower end shaft of the spline shaft (1) and the inner hole of the bushing base (2) respectively; S2: a rotation prevention pin is bonded in the groove of the lower end shaft of the spline shaft (1); and the lower end surface of the bushing base (2) is heated; S3: in the hot state of the bushing base (2), the spline shaft (1) with the bonded rotation prevention pin is pressed into the inner hole of the bushing base (2) along the axial direction, wherein the rotation prevention pin on the spline shaft (1) is matched with the groove of the bushing base (2); S4: after the assembled spline shaft (1) and the bushing base (2) are cooled, the joint is bonded with glue, and a spline bushing with a positioning platform and an external spline is obtained.

2. The method of claim 1, wherein, The spline shaft (1) comprises a spline profile (101), an empty cutting section (102) and an assembly shaft (103); the spline profile (101), the empty cutting section (102) and the assembly shaft (103) are sequentially arranged from top to bottom, and the assembly shaft (103) is connected with the bushing base (2).

3. The method of claim 1, wherein, The bushing base (2) has a stepped outer circle (201) and three-section inner holes, wherein the first inner hole (202) is matched with the spline shaft (1), the second inner hole (203) is empty, and the square hole (204) is a square hole; the first inner hole (202), the second inner hole (203) and the square hole (204) are sequentially arranged from top to bottom.

4. The method of claim 3, wherein, The cylindrical degree and coaxiality of the first inner hole (202) and the second inner hole (203) of the bushing base (2) and the stepped outer circle (201) are not greater than 0.01 mm.

5. The method of claim 3, wherein, The spline shaft (1) comprises a spline profile (101), an empty cutting section (102) and an assembly shaft (103), and S1 specifically comprises: S101: the spline shaft (1) and the bushing base (2) are turned to a preset outer diameter, center holes are formed on the two end surfaces of the spline shaft (1), a wire hole is formed at the square hole (204) of the bushing base (2), and then quenching and aging heat treatment is performed; S102: the first inner hole (202) and the second inner hole (203) of the bushing base (2) and the outer circle are ground to a specified size, and then the square hole (204) is processed by linear cutting based on the ground outer circle, and the coaxiality is not greater than 0.01 mm; S103: the spline profile (101) of the spline shaft (1) is ground to a specified size, the assembly shaft (103) of the spline shaft (1) is ground to an interference fit with the first inner hole (202) of the bushing base (2), and then the outer circle end surface is ground and the root is cleaned; S104: grooves are formed on the outer wall of the assembly shaft (103) of the spline shaft (1) and the inner wall of the first inner hole (202) of the bushing base (2) respectively.

6. The method of claim 1, wherein, The spline shaft (1) and the bushing base (2) are interference fit, and the interference amount is not greater than 0.005 mm.

7. The method of claim 1, wherein, In S2, the heating temperature is 500-550℃, and the heating time is 4-5 min.

8. The method of claim 1, wherein, In S1, the groove depth is 0.1-0.2 mm.

9. The method of claim 8, wherein, In S2, the size of the rotation prevention pin is matched with the groove, so that the groove can completely contain the maximum entity of the rotation prevention pin.

10. An externally splined bushing with a positioning station, characterized in that The spline bushing is prepared by the machining method in any one of claims 1-9.

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