Turning method for external star wheel with end face spline without center hole

Abstract

The present application discloses a turning method for an outer star wheel with end face splines without a center hole, comprising: step one, fixing the workpiece on a first fixture, the first fixture using the end face splines as the centering and positioning surface, and using the top to hold the inner surface of the bowl bottom of the workpiece for fixing, performing an outer circle rough turning process to form a rough turned outer circle and a process step surface; step two, fixing the workpiece on a second fixture, the second fixture using the rough turned outer circle as the clamping surface and the process step surface as the positioning surface for fixing, performing a large end face and inner hole fine turning process to form a fine turned large end face and a fine turned inner hole; step three, fixing the workpiece on a third fixture, the third fixture using the fine turned inner hole as the expansion holding surface and the fine turned large end face as the positioning surface for fixing, performing a small end face and outer circle fine turning process to form a fine turned small end face and a fine turned outer circle. The present application is easy to meet various processing requirements.

Description

Technical Field

[0001] The present application relates to the technical field of mechanical machining and turning, and in particular to a turning method for an outer star wheel with end face splines without a center hole. Background Art

[0002] The constant velocity joint is a key component in the car. It connects the input shaft and output shaft (also called the driving shaft and the driven shaft) connected to the constant velocity joint to complete the transmission of motion through a constant instantaneous angular velocity ratio. The constant velocity joint connects two shafts with non-coincident axes to achieve motion transmission at the same angular velocity.

[0003] According to the working characteristics, constant velocity joints can be divided into center fixed type and telescopic type, which are used at the hub end and gearbox end of the half shaft respectively. Among them, the VL-MB type constant velocity joint belongs to the telescopic type constant velocity joint, which is widely used at the gearbox end due to its advantages of high precision, long life, high strength and simple assembly, while the hub end usually uses the center fixed type constant velocity joint. However, with the continuous development of the automobile industry, the driving environment has become more complex, and higher requirements have been put forward for the performance of the drive shaft. Therefore, a new branch of the outer star wheel in the VL-MB type constant velocity joint has appeared, namely the VL-MB end face spline type outer star wheel, which is used at the hub end of the automobile half shaft. Through the end face spline of the outer star wheel and the corresponding part at the hub end, a locking meshing connection is carried out, which can adapt to the technical requirements of higher torque and lower noise, and a certain amount of telescopicity is also maintained while maintaining a large angle, ensuring the high adaptability of the car under complex road conditions, and the torsion resistance and NVH effect are very significant.

[0004] Since the measurement datum of the outer star wheel is to hold the chamfer of the inner hole and the center hole, and the runout of the small outer circle of the handle is ≤0.05, in order to unify the processing datum and the measurement datum and ensure that the size meets the requirements, the general processing method of this type of outer star wheel is to first use special equipment to process the center hole and end face of the handle, then clamp the inner hole, position it with the bottom of the bowl, and hold the center hole on the other side (one top and one clamp) to perform rough and fine turning of the overall shape contour, and finally clamp the outer circle, position the step surface, and process the inner hole and large end face. The characteristics of this method are that the processing datum is largely consistent with the measurement datum, and the runout size is relatively easy to control. However, the disadvantages are: (1) If the product has no center hole, it is impossible to process the center hole as the subsequent datum, so the traditional process is not suitable for this type of product; (2) Since the current rough turning process uses the bottom surface of the bowl as the rough datum to process the outer circle and datum surface. Since the thickness tolerance between the bowl bottom and the spline datum of the forging is relatively large (±0.75), if the bowl bottom is used as the positioning datum, the height of the spline and the end face after processing will also fluctuate greatly, and the size cannot be controlled within the required range. The consistency after each clamping is poor, resulting in unstable or even out-of-tolerance dimensions of the spline and the bowl bottom datum; (3) In addition, the runout tolerance between the spline datum circle and the inner hole and outer circle of the forging is relatively large (≤1), so no matter which one is chosen as the clamping datum, the processed parts will also have a large deviation, and it is closely related to the accuracy of the forging itself. From the perspective of machining, it cannot be actively controlled. The spline and the outer circle have runout requirements. If the inner hole is clamped for processing, due to the certain deviation between the inner hole and the spline (the maximum allowable runout between the inner hole and the end face spline is 1mm), it is necessary to rely entirely on the precision of the blank, and it cannot be guaranteed that the size after processing meets the runout requirements of the drawing (≤0.3mm). Summary of the invention

[0005] The purpose of the present application is to provide a turning method for an outer star wheel with end face splines without a center hole, which is easy to meet various processing requirements.

[0006] To achieve the above objectives, this application adopts the following technical solutions.

[0007] The present application provides a turning method for an outer star wheel with end face splines without a center hole, the machining method comprising:

[0008] Step 1: fix the workpiece on the first fixture, the workpiece is a precision forged spline blank, roughly in the shape of a bowl, with a large end face, a small end face and a side face between the large end face and the small end face, the side face has an end face spline, the end face spline faces the direction of the small end face, the first fixture uses the end face spline as a centering and positioning surface, and uses a center to support the inner surface of the bowl bottom of the workpiece for fixing, and performs an outer circle rough turning process to form a rough turned outer circle and a process step surface, the process step surface faces the direction of the end face spline;

[0009] Step 2: fix the workpiece on a second fixture, wherein the second fixture uses the rough-turned outer circle as a clamping surface and the process step surface as a positioning surface for fixing, and performs a large end face and inner hole fine turning process to form a fine-turned large end face and a fine-turned inner hole;

[0010] In step three, the workpiece is fixed on a third fixture, and the third fixture uses the fine-turned inner hole as a holding surface and the fine-turned large end surface as a positioning surface for fixing, and performs fine-turning of the small end surface and the outer circle to form a fine-turned small end surface and a fine-turned outer circle.

[0011] In one embodiment, the first fixture has a butt spline, the butt spline is engaged with the end face spline, and the butt spline and the end face spline are respectively made in the form of concave and convex molds.

[0012] In one embodiment, the top is a plane top with a floating function.

[0013] In one embodiment, the process step surface is manufactured by a reverse turning process.

[0014] In one embodiment, in the step 1, an outer circle rough turning step is performed, and the large end surface is also rough turned.

[0015] In one embodiment, in the step three, a small end face and outer circle finishing turning step is performed, and a grooving step is performed simultaneously.

[0016] In one embodiment, the front end of the first fixture has a first positioning block, the first positioning block has a docking spline, the docking spline is meshed with the end face spline, and at the same time, the inner surface of the bowl bottom of the workpiece is supported by a center point, so that the end face spline of the workpiece is close to the docking spline of the first positioning block, so as to achieve clamping and positioning of the workpiece, and complete the external cylindrical rough turning process through a turning program. After the processing is completed, the center point is released and retreated to remove the workpiece.

[0017] In one embodiment, the second tooling fixture is an external clamping type collet, and the front end of the external clamping type collet has a tapered cylinder with a rubber jacket inside, and the rubber jacket is connected to the disc-type pull rod through a coupling body. The reference pad is connected to the positioning disk through a thread and a step to ensure that the reference pad has no axial movement. The front end of the reference pad is connected to the second positioning block through a screw. After the small end face of the workpiece is inserted into the collet, the machine tool cylinder pulls backward, and the rubber jacket is driven to move backward through the disc-type pull rod and the coupling body. Under the action of the tapered cylinder, the inner diameter of the rubber jacket is reduced to hold the outer cylindrical surface of the workpiece. At the same time, due to the axial left movement of the rubber jacket, the workpiece can be pressed against the second positioning block to achieve clamping and positioning of the workpiece. The large end face and inner hole fine turning process is completed through the turning program. After the processing is completed, the machine tool cylinder pushes forward to release the rubber jacket and remove the workpiece.

[0018] In one embodiment, the third tooling fixture is an internal support type turning fixture. The front end of the main body of the internal support type turning fixture is provided with an outer cone surface, and an equiangular inner cone surface rubber expansion sleeve is provided to cooperate with it. There is an inner pull rod joint in the tail end hole of the main body, and a push rod is provided at the front end of the inner pull rod joint. An anti-rotation ring is provided at the front end of the push rod. The anti-rotation ring is coupled and linked to the rubber expansion sleeve, and the inner pull rod joint is connected to the pull bolt. The front end of the main body is connected with a third positioning block, and the inner hole of the workpiece is sleeved on the outside of the rubber expansion sleeve. The machine tool cylinder is pulled backward and the rubber expansion sleeve is driven to move backward through the pull bolt. Under the action of the taper, the outer diameter of the rubber expansion sleeve expands and tightens the inner hole of the workpiece. At the same time, due to the left movement of the rubber expansion sleeve, the workpiece is pressed against the third positioning block to achieve clamping and positioning of the workpiece. The small end face and outer circle finishing process is completed through the turning program. After the processing is completed, the machine tool cylinder is pushed forward, the inner pull rod joint moves to the right, and the pull bolt, the push rod and the anti-rotation ring are pushed to loosen the rubber expansion sleeve, remove the workpiece, and complete all processes.

[0019] In summary, the beneficial effects of the present application are as follows: the turning method of the external star wheel with end face spline without center hole solves the problem of positioning processing without center hole, directly uses the end face spline as processing and measurement reference, and minimizes measurement and processing errors under the condition of unified reference, significantly improves product quality and production efficiency, and reduces process quality risks. The end face spline is directly used as the rough reference to establish the centering and positioning surface, which lays the foundation for subsequent fine processing, solves the problem of shape and position size control of the end face spline relative to the reference surface, and makes it meet the requirements of the drawing. Moreover, among the three turning processes, only the first rough turning process uses the end face spline of the blank as the rough reference, and the latter two processes use the machined surface of the previous process as the fine reference, which complies with the principle of coincidence of machining references, ensures the positioning accuracy of subsequent processing, and ultimately ensures the accuracy of the finished product, especially the control of shape and position tolerances such as runout. In the final product, the coaxiality between the outer circle and inner hole of the end spline, small end face, large end face, the parallelism and the distance between the end spline, small end face, large end face, and the perpendicularity between the large end face and the inner hole are all good and easy to meet various processing requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of each embodiment of the present application, the drawings required for use in each embodiment will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of the positioning and fixing of a workpiece and the processing changes in each process of the turning method of the external star wheel with end splines without a center hole provided in the first embodiment of the present application;

[0022] Figure 2This is a schematic diagram of positioning and fixing a workpiece by a first fixture in step 1 of a turning method for a center hole-free end face spline outer star wheel provided in the first embodiment of the present application;

[0023] Figure 3 This is a schematic diagram of positioning and fixing the workpiece by the second fixture in step 2 of the turning method of the external star wheel with end splines without a center hole provided in the first embodiment of the present application;

[0024] Figure 4 This is a schematic diagram of positioning and fixing the workpiece by the third fixture in step three of the turning method for the external star wheel with end splines without a center hole provided in the first embodiment of the present application.

[0025] Description of main reference numerals:

[0026] The first fixture 11, the first positioning block 12,

[0027] Top 13, Second fixture 21,

[0028] Disc pull rod 22, positioning disc 23,

[0029] Reference pad 24, coupling body 25,

[0030] Cone 26, second positioning block 27,

[0031] Rubber jacket 28, third fixture 31,

[0032] Inner tie rod joint 32, top rod 33,

[0033] Anti-rotation ring 34, third positioning block 35,

[0034] Rubber expansion sleeve 36, pull bolt 37,

[0035] Workpiece 101. DETAILED DESCRIPTION

[0036] The following will be combined with 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 only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise stated, the directional words used, such as "up", "down", "left" and "right", can be the direction of the actual use or working state of the device, can also be the direction of the drawing with reference to the accompanying drawings, and can also refer to two relative directions; while "inside" and "outside" refer to the outline of the device.

[0037] See also Figure 1 As shown, the first embodiment of the present application provides a turning method for an outer star wheel with end face splines without a center hole, and the processing method comprises:

[0038] Step 1: fix the workpiece on the first fixture, the workpiece is a precision forged spline blank, roughly in the shape of a bowl, with a large end face, a small end face and a side face between the large end face and the small end face, the side face has an end face spline, the end face spline faces the direction of the small end face, the first fixture uses the end face spline as a centering and positioning surface, and uses a center to support the inner surface of the bowl bottom of the workpiece for fixing, and performs an outer circle rough turning process to form a rough turned outer circle and a process step surface, the process step surface faces the direction of the end face spline;

[0039] Step 2: fix the workpiece on a second fixture, wherein the second fixture uses the rough-turned outer circle as a clamping surface and the process step surface as a positioning surface for fixing, and performs a large end face and inner hole fine turning process to form a fine-turned large end face and a fine-turned inner hole;

[0040] In step three, the workpiece is fixed on a third fixture, and the third fixture uses the fine-turned inner hole as a holding surface and the fine-turned large end surface as a positioning surface for fixing, and performs fine-turning of the small end surface and the outer circle to form a fine-turned small end surface and a fine-turned outer circle.

[0041] The material of the precision forged spline blank is UC1 (CF53), which is high-quality medium carbon steel and is a special steel for transmission shafts. It has high strength, wear resistance, heat resistance, etc. It can be used in parts with large forces, wear resistance and torsion resistance. The main processing surfaces of the part are the entire outer circle contour, the two end faces and the inner hole surface, while the end face spline, bowl bottom and inclined surface of the part do not need to be processed and remain in the blank surface state.

[0042] The present application discloses a turning method for an outer star wheel with end face splines without a center hole, which solves the problem of being unable to position and process without a center hole. The end face splines are directly used as the processing and measurement reference. Under the condition of unified reference, the measurement and processing errors are minimized to the maximum extent, which significantly improves the product quality and production efficiency, and reduces the process quality risk. The end face splines are directly used as the rough reference to establish the centering and positioning surfaces, which lays the foundation for subsequent fine processing, solves the problem of controlling the shape and position dimensions of the end face splines relative to the reference surface, and makes it meet the requirements of the drawings. Moreover, among the three turning processes, only the first rough turning process uses the end face splines of the blank as the rough reference, and the latter two processes use the machined surface of the previous process as the fine reference, which complies with the principle of coincidence of machining references, ensures the positioning accuracy of subsequent processing, and ultimately ensures the accuracy of the finished product, especially the control of shape and position tolerances such as runout. In the final product, the coaxiality between the outer circle and inner hole of the end spline, small end face, large end face, the parallelism and distance between the end spline, small end face, large end face, and the perpendicularity between the large end face and the inner hole are all good.

[0043] In one embodiment, the first fixture has a butt spline, the butt spline meshes with the end face spline, and the butt spline and the end face spline are respectively made in the form of a concave and convex mold. In this way, on the one hand, the maximum meshing contact surface effect can be ensured, and on the other hand, it can play a role of both centering and positioning, thereby driving the processing of parts.

[0044] In one embodiment, the center is a plane center with a floating function. The center is clamped in place by the axial tightening force of the hydraulic tailstock, and can eliminate the parallelism error between the end face spline and the bottom surface of the blank bowl, avoid affecting the positioning accuracy of the part after over-positioning, and maintain the tightening force without affecting the centering positioning accuracy of the engagement between the fixture spline and the part spline.

[0045] In one embodiment, the process step surface is made by reverse turning process, so that the process step surface can be ensured to have good flatness, so as to be used as a positioning surface in subsequent processes.

[0046] In one embodiment, in the process 1, the outer circle rough turning process is performed, and the large end face is also rough turned. In this way, the time required to complete all processes can be reduced and the work efficiency can be improved. Of course, when the large end face is rough turned, a certain margin is still reserved for the subsequent fine turning process.

[0047] In one embodiment, in the process three, the small end face and outer circle finishing process is performed, and the grooving process is performed at the same time. Because some slots or grooves on the outer circle are relatively narrow and deep, the grooving process can better form these slots or grooves.

[0048] See also Figure 2As shown, in one embodiment, the front end of the first fixture 11 has a first positioning block 12, and the first positioning block 12 has a docking spline, which is engaged with the end face spline. At the same time, the inner surface of the bowl bottom of the workpiece 101 is supported by a top 13, so that the end face spline of the workpiece is close to the docking spline of the first positioning block 12, so as to achieve clamping and positioning of the workpiece 101, and the external cylindrical rough turning process is completed through a turning program. After the processing is completed, the top 13 is released and retreated, and the workpiece 101 is removed.

[0049] See also Figure 3 As shown, in one embodiment, the second fixture 21 is an external clamp collet, the front end of the external clamp collet has a conical cylinder 26, and a rubber jacket 28 is arranged inside, and the rubber jacket 28 is connected to the disc pull rod 22 through a coupling body 25. The reference pad 24 is connected to the positioning disk 23 through a thread and a step to ensure that the reference pad 24 does not move in the axial direction. The front end of the reference pad 24 is connected to the second positioning block 27 through a screw. After the small end face of the workpiece 101 is inserted into the collet, the machine tool oil The cylinder pulls backward, and the rubber jacket 28 is driven to move backward through the disc pull rod 22 and the coupling body 25. Under the action of the tapered cylinder 26, the inner diameter of the rubber jacket 28 is reduced, and the outer cylindrical surface of the workpiece 101 is embraced. At the same time, due to the axial left movement of the rubber jacket 28, the workpiece 101 can be pressed against the second positioning block 27, so that the workpiece 101 is clamped and positioned. The large end face and inner hole finishing process is completed through the turning program. After the processing is completed, the machine tool cylinder is pushed forward, the rubber jacket 28 is loosened, and the workpiece 101 is removed.

[0050] See also Figure 4 As shown, in one embodiment, the third tooling fixture 31 is an internal support type lathe fixture, the front end of the main body of the internal support type lathe fixture is provided with an outer cone surface, and an equiangular inner cone surface rubber expansion sleeve 36 is provided to cooperate with it, an inner tie rod joint 32 is provided in the rear end hole of the main body, a push rod 33 is provided at the front end of the inner tie rod joint 32, an anti-rotation ring 34 is provided at the front end of the push rod 33, the anti-rotation ring 34 is coupled and linked with the rubber expansion sleeve 36, the inner tie rod joint 32 is connected with a pull bolt 37, and the front end of the main body is connected with a third positioning block 35, the inner hole of the workpiece 101 is sleeved on the outside of the rubber expansion sleeve 36, and the machine The bed cylinder pulls backward, and drives the rubber expansion sleeve 36 to move backward through the pull bolt 37. Under the effect of the taper, the outer diameter of the rubber expansion sleeve 36 expands, tightening the inner hole of the workpiece 101. At the same time, due to the leftward movement of the rubber expansion sleeve 36, the workpiece 101 is pressed against the third positioning block 35, thereby clamping and positioning the workpiece 101. The small end face and outer circle finishing process is completed through the turning program. After the processing is completed, the machine tool cylinder is pushed forward, and the inner pull rod joint moves to the right 32, pushing the pull bolt 37, the push rod 33 and the anti-rotation ring 34, so that the rubber expansion sleeve 36 is loosened, the workpiece 101 is removed, and all processes are completed.

[0051] In the above processes, the equipment used are all general standard CNC lathes. Ready-made equipment can be used without the need for new purchases. Operators can easily get started without the need for retraining. In addition, the equipment layout can be more reasonable and compact as needed, providing a good foundation for automated production solutions.

[0052] In summary, the turning method of the external star wheel with end face spline without center hole in the present application solves the problem of positioning processing without center hole, and directly uses the end face spline as the processing and measurement reference. Under the condition of unified reference, the measurement and processing errors are minimized to the maximum extent, which significantly improves the product quality and production efficiency, and reduces the process quality risk. The end face spline is directly used as the rough reference to establish the centering and positioning surface, which lays the foundation for subsequent fine processing, solves the problem of shape and position size control of the end face spline relative to the reference surface, and makes it meet the requirements of the drawing. Moreover, among the three turning processes, only the first rough turning process uses the end face spline of the blank as the rough reference, and the latter two processes use the machined surface of the previous process as the fine reference, which complies with the principle of coincidence of machining references, ensures the positioning accuracy of subsequent processing, and ultimately ensures the accuracy of the finished product, especially the control of shape and position tolerances such as runout. On the final product, the coaxiality between the end face spline, the small end face, the outer circle of the large end face and the inner hole, the parallelism and distance between the end face spline, the small end face and the large end face, and the verticality between the large end face and the inner hole are all good, which significantly improves the product performance and quality, reduces the production scrap rate, and effectively controls the processing cost.

[0053] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0054] The technical solutions provided by the embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A turning method for an outer star wheel with end face splines without a center hole, characterized in that: The processing method comprises: In the first step, the workpiece is fixed on the first fixture. The workpiece is a precision forged spline blank, which is roughly bowl-shaped and has a large end face, a small end face and a side face between the large end face and the small end face. The side face has an end face spline, which faces the direction of the small end face. The first fixture uses the end face spline as a centering and positioning surface, and uses a top to support the inner surface of the bowl bottom of the workpiece for fixing, and performs an outer circle rough turning process to form a rough turned outer circle and a process step surface, and the process step surface faces the direction of the end face spline. The first fixture has a butt spline, which is meshed with the end face spline. The butt spline and the end face spline are respectively made in the form of concave and convex molds; the process step surface is made by reverse turning process. Step 2: fix the workpiece on a second fixture, wherein the second fixture uses the rough-turned outer circle as a clamping surface and the process step surface as a positioning surface for fixing, and performs a large end face and inner hole fine turning process to form a fine-turned large end face and a fine-turned inner hole; In step three, the workpiece is fixed on a third fixture, and the third fixture uses the fine-turned inner hole as a holding surface and the fine-turned large end surface as a positioning surface for fixing, and performs fine-turning of the small end surface and the outer circle to form a fine-turned small end surface and a fine-turned outer circle.

2. The turning method of the outer star wheel with end face spline without center hole as claimed in claim 1, characterized in that: The top is a plane top with a floating function.

3. The turning method of the outer star wheel with end face spline without center hole as claimed in claim 1, characterized in that: In the process 1, the outer circle is rough turned, and the large end surface is also rough turned.

4. The turning method of the outer star wheel with end face spline without center hole as claimed in claim 1, characterized in that: In the process three, the small end face and outer circle finishing process is carried out, and the grooving process is carried out at the same time.

5. The turning method of the outer star wheel with end face spline without center hole as claimed in claim 1, characterized in that: The front end of the first fixture is provided with a first positioning block, which has a docking spline, and the docking spline is meshed with the end face spline. At the same time, the inner surface of the bowl bottom of the workpiece is supported by a top point, so that the end face spline of the workpiece is close to the docking spline of the first positioning block, so as to achieve the clamping and positioning of the workpiece, and complete the external cylindrical rough turning process through the turning program. After the processing is completed, the top point is released and retreated to remove the workpiece.

6. The turning method of the outer star wheel with end face spline without center hole as claimed in claim 1, characterized in that: The second tooling fixture is an external clamping type collet, and the front end of the external clamping type collet has a tapered cylinder with a rubber jacket inside, and the rubber jacket is connected to the disc-type pull rod through a coupling body. The reference pad is connected to the positioning disk through threads and steps to ensure that the reference pad has no axial movement. The front end of the reference pad is connected to the second positioning block through a screw. After the small end face of the workpiece is inserted into the collet, the machine tool cylinder pulls backward, and the rubber jacket is driven to move backward through the disc-type pull rod and the coupling body. Under the action of the tapered cylinder, the inner diameter of the rubber jacket is reduced to hold the outer cylindrical surface of the workpiece. At the same time, due to the axial left movement of the rubber jacket, the workpiece can be pressed against the second positioning block to achieve clamping and positioning of the workpiece. The large end face and inner hole fine turning process is completed through the turning program. After the processing is completed, the machine tool cylinder pushes forward to release the rubber jacket and remove the workpiece.

7. The turning method of the outer star wheel with end face spline without center hole as claimed in claim 1, characterized in that: The third tooling fixture is an internal support type turning fixture. The front end of the main body of the internal support type turning fixture is provided with an outer cone surface, and an equiangular inner cone surface rubber expansion sleeve is provided to cooperate with it. There is an inner pull rod joint in the tail end hole of the main body, and a push rod is provided at the front end of the inner pull rod joint. An anti-rotation ring is provided at the front end of the push rod. The anti-rotation ring is coupled and linked to the rubber expansion sleeve, and the inner pull rod joint is connected to the pull bolt. The front end of the main body is connected with a third positioning block, and the inner hole of the workpiece is sleeved on the outside of the rubber expansion sleeve. The machine tool cylinder is pulled backward, and the rubber expansion sleeve is driven to move backward through the pull bolt. Under the action of the taper, the outer diameter of the rubber expansion sleeve expands and tightens the inner hole of the workpiece. At the same time, due to the left movement of the rubber expansion sleeve, the workpiece is pressed against the third positioning block to achieve clamping and positioning of the workpiece. The small end face and outer circle finishing process is completed through the turning program. After the processing is completed, the machine tool cylinder is pushed forward, the inner pull rod joint moves to the right, and the pull bolt, the push rod and the anti-rotation ring are pushed to loosen the rubber expansion sleeve, remove the workpiece, and complete all processes.

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