Main reduction gear grinding fixture for automobile reduction gearbox

Abstract

The application relates to the technical field of gear machining, in particular to a main reduction gear grinding clamp for an automobile reduction gearbox. The clamp comprises a clamp body, an expansion sleeve structure, a positioning block and a gland. The expansion sleeve structure comprises an expansion sleeve. The expansion sleeve is a ring structure which expands outward along the radial direction to clamp the inner circle of a workpiece when moving to one side of the axial direction, and shrinks inward along the radial direction to release the inner circle of the workpiece when moving to the other side of the axial direction. A plurality of positioning bosses arranged in the circumferential direction are arranged on the axial end surface of the positioning block in contact with the inner circle of the workpiece. The positioning boss is a convex structure protruding to the inner circle of the workpiece in the axial direction, and is used for positioning the workpiece. The adjacent positioning bosses are arranged in the interval to form a recess channel for discharging grinding impurities. The gland is fixed on the main shaft of a machine tool, and is arranged on the two sides of the axial direction of the workpiece together with the positioning block. The clamp has simple structure, high discharging efficiency of grinding mud and grinding wheel dust in the grinding process, and can effectively maintain the cleanliness of the positioning surface.

Description

Technical Field

[0001] This invention relates to the field of gear processing technology, specifically to a grinding fixture for the main reduction gear of an automotive gearbox. Background Technology

[0002] The main reduction gear is an important component of a car's gearbox, such as... Figure 1 The diagram shows a conventional main reduction gear. The main reduction gear has a ring-shaped structure. The outer end face of the workpiece 111 is a gear, and the inner end face has an inner ring 112 that protrudes radially towards the center. Multiple through holes 113 are formed on the inner ring 112, extending axially through it. During machining, a shrink-fit fixture is typically used to center the inner ring of the workpiece, and then the axial end face of the inner ring is positioned. Figure 1 As shown, C represents clamping and centering, and L represents support and positioning. After the workpiece is clamped, gear machining can be performed on the outer end face of the workpiece's circumference.

[0003] Grinding of main reduction gears is typically done using a gear grinding machine, primarily for the finishing of hardened gears. For example, a Chinese utility model patent with patent number "CN206578383U" entitled "A Grinding Fixture for Disc Gears" describes a grinding fixture for processing disc gears. This fixture includes a base, a piston, a tapered cylinder, an upper pull rod, a positioning plate, and a pressure plate. The piston is located between the base and the tapered cylinder, which is movably fitted onto the upper pull rod. The positioning plate is fixedly fitted onto the tapered cylinder, and the pressure plate and positioning plate are correspondingly arranged. Both ends of the piston are stepped shafts; one end of the piston is movably fitted onto the base, and the other end is movably fitted onto the tapered cylinder. A first oil chamber is formed between the piston and the base, connected to an oil source via a first oil passage. A second oil chamber is formed between the piston and the tapered cylinder, connected to an oil source via a second oil passage. Both the first and second oil chambers are sealed with sealing rings. In actual operation, the workpiece can be clamped or released by controlling the pressure of the first and second oil chambers, making the operation relatively simple. However, this fixture has many problems during use.

[0004] During grinding, the abrasive grains of the grinding wheel and the workpiece undergo both cutting, scratching, and friction, generating a large amount of grinding heat. The temperature in the grinding zone can reach approximately 400–1000℃. The grinding wheel wears down, and the abrasive grains that detach from the wheel surface form grinding wheel dust, while the material removed from the workpiece surface forms grinding mud. Both of these materials are splashed onto the fixture by the grinding oil sprayed from the nozzle. The grinding mud generated also splashes into the machine tool's machining chamber (such as the grinding wheel spindle and workpiece spindle center seat) with the rotating grinding wheel. If this accumulated grinding mud is not cleaned in time, it will also fall onto the fixture. In addition, a large amount of grinding mud accumulates in the machine tool's oil tank. The grinding oil is filtered and circulated from the oil tank by the machine tool's filtration system, and the unfiltered grinding mud impurities will splash onto the fixture along with the grinding oil sprayed from the nozzle. This leads to the following two problems in the current main reduction gear or disc gear machining process: 1. The fixture has a wide positioning surface for the workpiece. Grinding wheel dust and grinding mud that fall off the grinding wheel can easily adhere to the positioning surface of the fixture, causing the workpiece end face support positioning accuracy to be lost (even with end face airtightness testing, its accuracy cannot identify the adhesion of grinding wheel dust and grinding mud), resulting in the tooth direction consistency of the ground workpiece exceeding the tolerance (rough teeth), and the processed parts being scrapped. 2. The conical surface where the fixture body mates with the expansion sleeve is prone to being covered with grinding mud. Over time, this mud can affect the clamping and centering accuracy of the expansion sleeve, leading to substandard product quality. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a grinding fixture for the main reduction gear of an automotive gearbox.

[0006] The technical solution of this invention is: a grinding fixture for the main reduction gear of an automotive reduction gearbox, comprising, Fixture body; An expansion sleeve structure, comprising an expansion sleeve that is axially movable and disposed at one axial end of the fixture body; the expansion sleeve is an annular structure that is inserted into the inner ring of the workpiece, expands radially outward to clamp the inner ring of the workpiece when moving to one axial side, and contracts radially inward to loosen the inner ring of the workpiece when moving to the other axial side. The positioning block is a ring-shaped structure fixed on the fixture body. Multiple positioning bosses are provided on the axial end face of the positioning block that contacts the inner ring of the workpiece. The positioning bosses are protruding structures that protrude axially toward the inner ring of the workpiece for positioning the workpiece. Adjacent positioning bosses are arranged at intervals to form recessed channels for discharging grinding impurities. A pressure cap is fixed on the machine tool spindle and placed on both sides of the workpiece along with a positioning block, for positioning the axial end face of the workpiece.

[0007] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein the positioning boss has an axially recessed oil drain groove on the side facing the inner ring of the workpiece; the oil drain groove is located at the radial middle position of the positioning boss and penetrates the positioning boss circumferentially.

[0008] According to the grinding fixture for the main reduction gear of an automotive gearbox provided in this application, the bottom surface of the oil drain groove is an inclined surface that is higher on one side and lower on the other side along the circumferential direction; the inclination direction of the bottom surfaces of adjacent oil drain grooves is the same; Furthermore, the bottom surface of the oil drain groove in this application is an inclined surface that gradually decreases along the direction of rotation.

[0009] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein the width of the oil drain groove in the radial direction is greater than the diameter of the inner ring through hole.

[0010] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein the recessed channel is an inclined surface that is higher on the radial side near the center and lower on the side away from the center.

[0011] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein an axial drain hole extending along the axial direction is provided on the recessed channel; one axial end of the axial drain hole is located on the recessed channel, and the other axial end is connected to the inner and outer sides of the positioning block through a drain structure.

[0012] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein the oil draining structure includes a radial oil drain hole; the radial oil drain hole penetrates the positioning block radially, and the radial oil drain hole is connected to the end of the axial oil drain hole away from the recessed channel.

[0013] According to the grinding fixture for the main reduction gear of an automotive gearbox provided in this application, the radial drain hole is an inclined hole that is higher on the side closer to the center of the positioning block and lower on the side farther from the center of the positioning block.

[0014] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein a first purging structure for cleaning the positioning surface of the positioning block is provided between the fixture body and the positioning block.

[0015] According to the grinding fixture for the main reduction gear of an automotive gearbox provided in this application, the first purging structure includes... The first air passage is a gas passage arranged radially on the fixture body; The second air passage is a gas passage arranged axially on the fixture body. One end of the second air passage is connected to the first air passage, and the other end extends axially to the end face of the fixture body that contacts the positioning block. The third air passage is a gas passage arranged axially on the positioning block. One end of the first air passage is connected to one end of the second air passage that extends to the axial end face of the fixture body, and the other end extends axially to the positioning surface where the positioning block contacts the inner ring of the workpiece.

[0016] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein a second purging structure for cleaning the contact surfaces of the fixture body and the expansion sleeve is provided.

[0017] According to the grinding fixture for the main reduction gear of an automotive gearbox provided in this application, the second purging structure includes... The fourth air passage is a gas passage arranged axially on the fixture body. One end of the fourth air passage is connected to the first air passage, and the other end extends axially towards the end of the fixture body near the expansion sleeve. The fifth air passage is a gas passage arranged radially on the fixture body. One end of the fifth air passage is connected to the fourth air passage, and the other end extends radially to the end face of the fixture body that contacts the expansion sleeve.

[0018] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein an airtightness detection structure for determining whether the expansion sleeve has moved axially into place is provided between the fourth air passage and the fifth air passage.

[0019] According to the grinding fixture for the main reduction gear of an automotive gearbox provided in this application, the airtightness detection structure includes... The push rod is a rod-shaped structure with one end axially inserted into the fourth air passage near the expansion sleeve. The other end of the push rod is fixedly connected to the expansion sleeve. When the push rod moves axially with the expansion sleeve to coincide with the fifth air passage in the axial direction, it cuts off the connection between the fourth and fifth air passages. When the push rod moves axially with the expansion sleeve to a position where it does not coincide with the fifth air passage in the axial direction, it connects the fourth and fifth air passages. A spring, one end of which is fixed to the end of the push rod away from the expansion sleeve, and the other end of which is fixed inside the fourth air passage.

[0020] According to the grinding fixture for the main reduction gear of an automotive gearbox provided in this application, the expansion sleeve structure includes... A pull rod, which passes through the clamp body axially and is arranged coaxially with the clamp body, with one end of the pull rod fixedly connected to the expansion sleeve; A base, which is fixed to the end of the clamp body away from the expansion sleeve; The piston is axially movable and is disposed in the clamp body. A first piston chamber is formed between the piston on one axial side and the base, and a second piston chamber is formed between the piston on the other axial side and the clamp body. The piston is fixedly connected to the other end of the pull rod. The first oil passage is disposed on the base and is connected to the first piston chamber for injecting oil into the first piston chamber to drive the piston to move axially toward the side closer to the expansion sleeve. The second oil passage is located on the base and the fixture body. The second oil passage is connected to the second piston chamber and is used to inject oil into the second piston chamber to drive the piston to move axially away from the expansion sleeve.

[0021] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein the outer circumferential end face of the part of the fixture body that contacts the expansion sleeve is a first conical surface that is smaller at the end closer to the expansion sleeve and larger at the end farther from the expansion sleeve; the inner circumferential end face of the part of the expansion sleeve that contacts the fixture body is a second conical surface that fits with the first conical surface that is larger at the end farther from the pressure cap and smaller at the end closer to the pressure cap; and the outer circumferential end face of the expansion sleeve is an annular curved surface with the same diameter.

[0022] According to the present application, a grinding fixture for the main reduction gear of an automotive gearbox is provided, wherein the pressure cover is a floating clamping structure that can move axially.

[0023] The advantages of this application are: 1. When clamping the workpiece, the fixture of this application reduces the positioning surface between the positioning block and the workpiece by setting the positioning surface of the positioning block as multiple positioning bosses, and forms a recessed channel for discharging grinding impurities between adjacent positioning bosses. This facilitates the quick discharge of grinding impurities during the grinding process of the workpiece, and avoids grinding mud and grinding wheel dust adhering to the positioning surface, which would affect the support and positioning accuracy. The fixture of this application has a "self-cleaning" function, which can better ensure the support and positioning accuracy of the fixture. 2. This application provides an oil drain groove on the positioning boss. The oil drain groove can further improve the discharge of grinding mud and grinding wheel dust with the oil, and prevent these impurities from adhering to the positioning surface of the positioning boss, thereby improving the cleanliness of the entire positioning surface. 3. The oil drain groove of this application is inclined along the circumferential direction of rotation. This design structure facilitates the flow of oil so that impurities such as grinding mud and grinding wheel dust can be smoothly discharged from the positioning block along with the grinding oil. This further improves the efficiency of the oil in carrying away grinding mud and grinding wheel dust, making it more difficult for grinding mud and grinding wheel dust to adhere in the oil drain groove. 4. The width of the oil drain groove in this application is greater than the diameter of the inner ring through hole. During the positioning and clamping process, the positioning boss can avoid the inner ring through hole, ensuring that the grinding mud entering the inner ring through hole can flow out along the oil drain groove with the grinding oil. 5. The recessed channel of this application is an inclined end face with a higher inner surface and a lower outer surface. Such an inclined end face facilitates the rapid ejection of oil, further improving the efficiency of oil flow and accelerating the discharge of grinding mud and grinding wheel dust. 6. This application provides an axial oil drain hole in the recessed channel, which facilitates the rapid flow of grinding oil through the axial oil drain hole, avoids the oil carrying grinding mud adhering to the positioning surface, and improves the oil flow rate. 7. This application provides a radial oil drain hole that penetrates the positioning block and communicates with the axial oil drain hole, making the oil flow on both the inner and outer sides of the positioning block more efficient and facilitating the rapid removal of grinding mud from the positioning block. 8. The radial drain hole of this application is an inclined hole with the inner side higher than the outer side, which facilitates the discharge of oil from the inside of the positioning block to the outside, and carries away grinding mud and other impurities from the inside of the positioning block. 9. This application sets up a first blowing structure to blow the positioning surface of the positioning block, so that the positioning block has a self-cleaning function, avoids the adhesion and contamination of grinding mud and grinding wheel dust on the positioning surface, and improves the positioning accuracy of the entire fixture. 10. The first purging structure of this application is very simple. The positioning surface can be easily purged and cleaned through the air passage structure, making it extremely convenient to use. 11. This application cleans the contact surface between the fixture body and the expansion sleeve through a second purging structure to ensure that the relative movement between the expansion sleeve and the fixture body is accurate and to avoid debris adhering to the contact surface from affecting the clamping and release of the workpiece. 12. The second purging structure of this application is very simple. By combining it with the first air passage, it can easily clean the contact surface between the fixture body and the expansion sleeve, avoiding the adhesion of grinding mud and grinding wheel dust. 13. This application provides an airtightness detection structure between the fourth and fifth air passages, which can detect the axial movement position of the expansion sleeve and determine whether it has moved into place and whether the workpiece is clamped or released. 14. The airtightness detection structure of this application is simple and extremely convenient to use based on the second purging structure, which improves the accuracy of fixture operation; 15. The expansion sleeve structure of this application is very convenient to use. By configuring the oil circuit structure, the radial expansion or contraction of the expansion sleeve can be realized. The operation is simple, and it is extremely easy to clamp and release the workpiece, which improves the efficiency of workpiece processing. 16. The contact surface between the expansion sleeve and the fixture body of this application is a conical structure. The conical structure makes the expansion and contraction of the expansion sleeve continuous, which makes the clamping and release of the workpiece very precise and simple to operate. 17. The pressure cap of this application is a floating structure, an axial floating structure, which facilitates the mud removal operation between the positioning block and the workpiece, greatly improving the removal efficiency of grinding mud and grinding wheel dust. It can ensure that the pressure cap can better fit the upper end face of the workpiece (the upper end face of the workpiece is not processed after heating, and has a large flatness), which plays a certain role in preventing grinding mud, grinding wheel dust and other impurities from falling or splashing onto the positioning block (the diameter of the pressure cap is larger than the diameter of the positioning block).

[0024] The fixture in this application has a simple structure and is easy to operate. It has a very high efficiency in removing grinding mud and grinding wheel dust during the grinding process, effectively maintaining the cleanliness of the positioning surface, and improving the support positioning accuracy and clamping centering accuracy of the main reduction gear machining. It has great promotional value. Attached Figure Description

[0025] Figure 1 : A schematic diagram of the workpiece cross-section in this application; Figure 2 : A schematic diagram of the cross-section of the workpiece held by the fixture in this application; Figure 3 : A schematic diagram of how the push rod movement in this application disconnects the fourth and fifth air passages; Figure 4 : A schematic diagram of the push rod movement in this application connecting the fourth and fifth air passages; Figure 5 : Axial view of the positioning block structure of this application; Wherein: 1—Clamp body; 2—Expansion sleeve; 3—Positioning block; 4—Positioning boss; 5—Recessed channel; 6—Pressure cap; 7—Oil drain groove; 8—Axial oil drain hole; 9—Radial oil drain hole; 10—First air passage; 11—Second air passage; 12—Third air passage; 13—Fourth air passage; 14—Fifth air passage; 15—Push rod; 16—Spring; 17—Pull rod; 18—Base; 19—Piston; 20—First oil passage; 21—Second oil passage; 22—Cylindrical pin; 23—O-ring seal; 111—Workpiece; 112—Inner ring; 113—Through hole. Implementation

[0026] Embodiments of the present invention are described in detail below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] This application relates to a grinding fixture for the main reduction gear of an automotive gearbox, used to clamp and fix the workpiece to be processed during the gear reduction process. This application improves the fixture by adding a discharge structure for grinding mud and grinding wheel dust, preventing grinding mud and grinding wheel dust from adhering to the positioning surface of the fixture on the workpiece and affecting the clamping and positioning accuracy of the fixture. This gives the fixture a certain self-cleaning function, eliminates the accumulation of grinding mud and grinding wheel dust on the fixture, improves the clamping and centering accuracy of the fixture on the workpiece, improves the machining accuracy of the workpiece, and avoids the situation of the machined parts being out of tolerance or scrapped.

[0031] Specifically, such as Figures 2-5 As shown, the grinding fixture for the main reduction gear of an automotive gearbox of this application includes a fixture body 1, an expansion sleeve structure, a positioning block 3, and a pressure cap 6. The fixture body 1 is an annular structure. The expansion sleeve structure includes an expansion sleeve 2 that is axially movable and disposed at one axial end of the fixture body 1. The expansion sleeve 2 is an annular structure that expands radially outward to clamp the inner ring of the workpiece when it is inserted into the inner ring of the workpiece and contracts radially inward to loosen the inner ring of the workpiece when it is moved to the other axial side. Most of the expansion sleeve structure is located inside the fixture body 1. The expansion or contraction of the expansion sleeve 2 is controlled. This allows for the clamping or release of the workpiece. The positioning block 3 is a ring-shaped structure fixed on the fixture body 1. Multiple positioning bosses 4 are arranged circumferentially on the axial end face of the positioning block 3 that contacts the inner ring of the workpiece. The positioning bosses 4 are protruding structures that protrude axially toward the inner ring of the workpiece for positioning the workpiece. The adjacent positioning bosses 4 are arranged at intervals to form recessed channels 5 for discharging grinding impurities. The pressure cover 6 is fixed on the machine tool spindle and is placed on both sides of the workpiece axially with the positioning block 3 for positioning the axial end face of the workpiece.

[0032] As attached Figure 1 As shown, the positioning block 3 of this application is clamped on the axial end face of the inner ring of the workpiece, that is... Figure 1 As shown in section L, the pressure cap 6 is clamped on the opposite end face of the workpiece along its axial direction. Figure 1 In the R portion shown, the outer circumferential end face of the expansion sleeve 2 is positioned on the inner end face of the inner ring of the workpiece, that is... Figure 1 Part C is shown in the diagram.

[0033] In actual operation, the inner ring of the workpiece to be processed is placed on the expansion sleeve 2, so that the axial end face of the inner ring of the workpiece contacts the positioning boss 4 of the positioning block 3. The pressure cover 6 is connected to the center hole of the machine tool spindle through its own Morse taper, so that the pressure cover 6 is clamped on the other axial end face of the workpiece. The expansion sleeve 2 is driven to move axially by the expansion sleeve structure. During the movement, the expansion sleeve 2 expands radially outward. The outer circumferential end face of the expansion sleeve 2 presses against the inner circumferential end face of the inner ring of the workpiece, clamping and positioning the workpiece, thus completing the clamping and fixing of the workpiece. During the grinding process, grinding mud and grinding wheel dust generated during grinding adhere to the positioning block. At this time, under the flushing action of the flowing grinding oil, the grinding oil will flow on the surface of the positioning block 3, and the grinding oil will wash away the grinding mud and grinding wheel dust adhering to the positioning block 3 and discharge it along the recessed channel 5. The positioning block 3 can always maintain a relatively clean state, especially the positioning surface of the positioning block 3 in contact with the workpiece is clean, which will not affect the positioning accuracy of the positioning block 3 for the workpiece.

[0034] In some embodiments of this application, the structure of the positioning block 3 described above has been further optimized, such as... Figure 2 and 5 As shown, the positioning boss 4 has an axially recessed oil drain groove 7 on the side facing the inner ring of the workpiece. The oil drain groove 7 is located at the radial center of the positioning boss 4 and extends circumferentially through the positioning boss 4. In this embodiment, by providing the oil drain groove 7 on the axial end face of the positioning boss 4, the area for oil flow is effectively increased. At the same time, the oil drain groove 7 reduces the contact area between the positioning boss 4 and the inner ring of the workpiece, reducing the area where oil cannot flow. The larger area for oil flow results in a better flushing effect on the positioning block 3.

[0035] The oil drain groove 7 is circumferentially connected to the positioning boss 4. This means that the grinding oil can flow in the oil drain groove 7 in the circumferential direction and will not accumulate on the positioning boss 4. The two sides of the oil drain groove 7 are connected to the recessed channels 5 on both sides of the positioning boss 4. The oil flowing out of the oil drain groove 7 enters the recessed channels 5 and is discharged. The oil flow is smooth and the removal of grinding sludge is very efficient.

[0036] This embodiment further optimizes the structure of the oil drain trough 7, such as... Figure 5 As shown, the bottom surface of the oil drain groove 7 in this embodiment is an inclined surface that is higher on one side and lower on the other side along the circumference, and the bottom surfaces of adjacent oil drain grooves 7 have the same inclination direction. The bottom surface of the oil drain groove 7 is set as an inclined end face to facilitate further flow of oil. The oil will not stay on the bottom surface of the oil drain groove 7 for a long time. The inclined bottom surface accelerates the oil flow rate and has a better effect on the discharge of grinding mud and grinding wheel dust.

[0037] The above structure is mainly designed to improve the circumferential flow of the oil, facilitating efficient circumferential flow and thus removing and carrying away the adhering grinding sludge and wheel dust. To further enhance the oil flushing effect, this embodiment also further optimizes the structure of the oil drain groove 7, such as... Figure 5 As shown, in this embodiment, the width of the oil drain groove 7 in the radial direction is greater than the diameter of the inner ring through hole.

[0038] Alternatively, in this embodiment, the oil drain groove 7 completely covers the inner ring through hole in the axial direction, which means that the positioning boss 4 in the axial direction will not obstruct the inner ring through hole in any way. The grinding oil flowing out of the inner ring through hole can directly enter the oil drain groove 7, which facilitates the discharge of grinding mud and grinding wheel dust from the inner ring through hole through the oil drain groove 7 under the flushing action of the oil.

[0039] In other embodiments of this application, the recessed channel 5 described above has been further optimized, specifically, as follows: Figure 5 As shown, the recessed channel 5 is an inclined surface that is higher on the radial side closer to the center and lower on the side farther from the center. The recessed channel 5 is designed with an inclined surface structure to facilitate the flow of oil along the inclined surface. The inclined surface, which is higher on the inside and lower on the outside, facilitates the outward ejection of oil, allowing the oil to quickly discharge along with grinding mud and grinding wheel dust, thus preventing the accumulation of the above-mentioned impurities on the positioning block 3.

[0040] In addition, this embodiment also provides an axially extending oil drain hole 8 on the recessed channel 5. One axial end of the axially extending oil drain hole 8 is located on the recessed channel 5, and the other axial end is connected to the inner and outer sides of the positioning block 3 through the oil drain structure.

[0041] Specifically, such as Figure 5 As shown, the oil drain structure includes a radial oil drain hole 9, which penetrates the positioning block 3 radially, and the radial oil drain hole 9 is connected to the end of the axial oil drain hole 8 away from the recessed channel 5.

[0042] The arrangement of axial drain holes 8 and radial drain holes 9 further enhances the area for oil flow. During the grinding process, the oil will not only be thrown outward on the inclined recessed channel 5, but also the flow through the axial drain holes 8 and radial drain holes 9 will further accelerate the discharge speed of grinding mud and grinding wheel dust.

[0043] Meanwhile, to facilitate the outward discharge of grinding mud and grinding wheel dust, the radial oil drain hole 9 in this embodiment is an inclined hole with a higher side near the center of the positioning block 3 and a lower side away from the center of the positioning block 3. The inclined radial oil drain hole 9 facilitates the flow of oil from the inside to the outside. The oil inside the positioning block 3 will carry the grinding mud and grinding wheel dust to the outside of the positioning block 3 and be discharged, avoiding the accumulation inside the positioning block 3 and causing adverse effects.

[0044] In a further embodiment of this application, the structure of the fixture body 1 described above has been optimized, specifically, as follows: Figure 2 As shown, a first purging structure for cleaning the positioning surface of the positioning block 3 is provided between the fixture body 1 and the positioning block 3. The first purging structure includes a first air passage 10, a second air passage 11, and a third air passage 12. The first air passage 10 is a gas passage arranged radially on the fixture body 1; the second air passage 11 is a gas passage arranged axially on the fixture body 1, with one end connected to the first air passage 10 and the other end extending axially to the end face of the fixture body 1 that contacts the positioning block 3; the third air passage 12 is a gas passage arranged axially on the positioning block 3, with one end of the first air passage 10 connected to one end of the second air passage 11 that extends to the axial end face of the fixture body 1, and the other end extending axially to the positioning surface of the positioning block 3 that contacts the inner ring of the workpiece.

[0045] In this embodiment, the end of the first air passage 10 furthest from the expansion sleeve 2 is connected to an air supply device. Pressurized air is introduced into the first air passage 10 through the air supply device. The pressurized air passes through the first air passage 10, the second air passage 11, and the third air passage 12 and is sprayed out from the axial end face of the positioning boss 4 (the outlet end of the third air passage 12 is located on the axial end face of the positioning boss 4, which is the positioning surface that contacts the inner ring of the workpiece). This blows away impurities such as grinding mud and grinding wheel dust adhering to the positioning surface, preventing these impurities from accumulating on the positioning surface and causing deviation of the positioning block 3 from the centering of the workpiece.

[0046] In this embodiment, multiple sets of first blowing structures can be set on the fixture body 1 and the positioning block 3. The multiple sets of first blowing structures are arranged at equal intervals along the circumference. Each set of first blowing structures corresponds to a positioning boss 4. That is, this embodiment can achieve the purpose of blowing the positioning surface of each positioning boss 4.

[0047] In a preferred embodiment of this application, a second purging structure for cleaning the contact surfaces of the clamp body 1 and the expansion sleeve 2 is provided between them. For example... Figure 2 As shown, the second purging structure includes a fourth air passage 13 and a fifth air passage 14. The fourth air passage 13 is a gas passage arranged axially on the clamp body 1. One end of the fourth air passage 13 is connected to the first air passage 10, and the other end extends axially towards the end of the clamp body 1 near the expansion sleeve 2. The fifth air passage 14 is a gas passage arranged radially on the clamp body 1. One end of the fifth air passage 14 is connected to the fourth air passage 13, and the other end extends radially to the end face of the clamp body 1 that contacts the expansion sleeve 2.

[0048] The second purging structure in this embodiment is an additional purging structure added to the first purging structure. Unlike the first purging structure, the second purging structure in this embodiment is used to purge the contact surface between the clamp body 1 and the expansion sleeve 2. The contact surface between the clamp body 1 and the expansion sleeve 2 is also exposed, and grinding sludge and grinding wheel dust can accumulate there. When grinding sludge and grinding wheel dust adhere to the contact surface, pressurized air is introduced into the first air passage 10 through the air supply device. The pressurized air passes through the first air passage 10, the second air passage 11, the fourth air passage 13, and the fifth air passage 14, and is sprayed out from the contact surface between the clamp body 1 and the expansion sleeve 2 to purge the contact surface between the clamp body 1 and the expansion sleeve 2, causing the grinding sludge and grinding wheel dust adhering to it to detach from the contact surface, preventing accumulation at this location and causing uneven operation of the expansion sleeve 2.

[0049] Similarly, in this embodiment, multiple sets of the second purging structure can be set up. The multiple sets of the second purging structure are arranged at equal intervals along the circumference. Each set of the second purging structure is responsible for cleaning a part of the contact surface. The multiple sets of the second purging structure work together to perform a complete and thorough cleaning of the contact surface.

[0050] It is worth noting that the second purging structure in this embodiment can only clean the contact surface when the clamp is detached, that is, when the expansion sleeve 2 is not expanding outward in the radial direction to clamp the inner ring of the workpiece. At this time, there is a gap between the expansion sleeve 2 and the clamp body 1, and the gas ejected from the fifth air passage 14 can purge between the expansion sleeve 2 and the clamp body 1 to complete the cleaning work.

[0051] In a further embodiment of this application, an airtightness detection structure is added to the second purging structure described above. An airtightness detection structure for determining whether the expansion sleeve 2 has moved axially into place is provided between the fourth air passage 13 and the fifth air passage 14. For example... Figures 2-4 As shown, the airtightness detection structure of this embodiment includes a push rod 15 and a spring 16. The push rod 15 is a rod-shaped structure with one end axially inserted into the fourth air passage 13 near the expansion sleeve 2. The other end of the push rod 15 is fixedly connected to the expansion sleeve 2. When the push rod 15 moves axially with the expansion sleeve 2 to coincide with the fifth air passage 14 in the axial direction, it cuts off the connection between the fourth air passage 13 and the fifth air passage 14. When the push rod 15 moves axially with the expansion sleeve 2 to not coincide with the fifth air passage 14 in the axial direction, it connects the fourth air passage 13 and the fifth air passage 14. One end of the spring 16 is fixed to the end of the push rod 15 away from the expansion sleeve 2, and the other end is fixed inside the fourth air passage 13.

[0052] The push rod 15 is a rod-shaped structure that moves axially with the expansion sleeve 2. An O-ring 23 is located at the front end of the push rod 15 away from the expansion sleeve 2. During the axial movement of the push rod 15 with the expansion sleeve 2, the spaces on both sides of the O-ring 23 are not connected. When the expansion sleeve 2 moves axially away from the pressure plate 6, it expands radially outward, clamping and fixing the inner ring of the workpiece. At this time, the push rod 15 moves axially with the expansion sleeve 2 away from the pressure plate 6, and the O-ring 23 passes the inlet end of the fifth air passage 14. Figure 3 As shown, the inlet end of the fifth air passage 14 is located between the O-ring 23 and the pressure cap 6. The push rod 15, in conjunction with the O-ring 23, cuts off the fourth air passage 13 and the fifth air passage 14, so the fourth air passage 13 and the fifth air passage 14 are no longer connected to each other. The gas is ejected from the axial end face of the positioning boss 4 through the first air passage 10, the second air passage 11 and the third air passage 12, forming an airtightness detection channel. If the pressure of the airtightness detection channel is within the set range, it proves that the axial movement of the expansion sleeve 2 is in place. Otherwise, the axial movement of the expansion sleeve 2 is not in place. In this way, it is possible to detect whether the workpiece is properly clamped on the fixture.

[0053] When the push rod 15 moves axially away from the pressure cover 6 along the expansion sleeve 2, it will compress the spring 16. After the workpiece processing is completed, the expansion sleeve 2 moves axially towards the pressure cover 6, and the spring 16 will play a reset role, pushing the push rod 15 axially towards the pressure cover 6.

[0054] This embodiment has multiple sets of airtightness detection structures, which are arranged at equal intervals along the circumference.

[0055] In some embodiments of this application, the above-described expansion sleeve structure has been optimized, specifically, as follows: Figure 2 As shown, the expansion sleeve structure of this embodiment includes a pull rod 17, a base 18, a piston 19, a first oil passage 20, and a second oil passage 21. The pull rod 17 passes through the clamp body 1 axially and is arranged coaxially with the clamp body 1. One end of the pull rod 17 is fixedly connected to the expansion sleeve 2. The base 18 is fixed at the end of the clamp body 1 away from the expansion sleeve 2, and the base 18 is used to seal one end of the clamp body 1. The piston 19 is axially movable and is disposed inside the clamp body 1. A first piston cavity is formed between the axial side of the piston 19 and the base 18. A second piston chamber is formed between the piston 19 on the other side of the axial direction and the clamp body 1. The piston 19 is fixedly connected to the other end of the pull rod 17. The first oil passage 20 is provided on the base 18 and is connected to the first piston chamber for injecting oil into the first piston chamber to drive the piston 19 to move axially toward the side closer to the expansion sleeve 2. The second oil passage 21 is provided on the base 18 and the clamp body 1 and is connected to the second piston chamber for injecting oil into the second piston chamber to drive the piston 19 to move axially away from the expansion sleeve 2.

[0056] In actual operation, when it is necessary to control the expansion sleeve 2 to clamp and fix the workpiece, the second oil circuit 21 is opened and the first oil circuit 20 is closed. Oil is supplied to the second oil circuit 21, and the pressurized oil enters the second piston chamber through the second oil circuit 21. The pressure in the second piston chamber increases, driving the piston 19 to move axially away from the pressure plate 6. Under the action of the piston 19, the pull rod 17, together with the expansion sleeve 2, moves axially away from the pressure plate 6. Under the action of the clamp body 1, the expansion sleeve 2 expands radially outward until the outer circumferential end face of the expansion sleeve 2 is tightly attached to the workpiece. The first oil circuit 20 is opened and the second oil circuit 21 is closed to control the expansion sleeve 2 to release the workpiece. Oil is supplied to the first oil circuit 20 and the chemical oil enters the first piston chamber through the first oil circuit 20. The pressure in the first piston chamber increases, pushing the piston 19 to move axially toward the pressure cover 6. Driven by the piston 19, the pull rod 17 moves axially toward the pressure cover 6 together with the expansion sleeve 2. The expansion sleeve 2 contracts radially inward until the outer circumferential end face of the expansion sleeve 2 is separated from the inner ring of the workpiece, thus releasing the workpiece.

[0057] In this embodiment, the first piston chamber is a sealed cavity formed by the base 18, the clamp body 1, and the piston 19. A sealing ring is provided on the stationary contact surface of the contact component, and a Gladwell ring is provided on the moving contact surface of the contact component. The second piston chamber is a sealed cavity formed by the clamp body 1 and the piston 19. A Gladwell ring is provided on the moving contact surface of the contact component.

[0058] In practical applications, to facilitate the arrangement of the air passage structure, this embodiment provides a sixth air passage at the axial midpoint of the piston 19. The sixth air passage includes an axial air passage along the axial direction and a radial air passage along the radial direction. The axial air passage passes through the piston 19 and connects with the air supply device passing through the base 18. The other end of the axial air passage connects with the radial air passage, and the other end of the radial air passage connects with an air groove formed along the axial direction on the outer circumference end face of the piston 19. The air groove connects with the first air passage 10. When the piston 19 moves axially, the air groove always connects with the first air passage 10, providing high-pressure gas stably for the first and second purging structures, facilitating purging operations.

[0059] In addition, to prevent relative rotation between the piston 19 and the clamp body 1 during axial movement, this embodiment provides a plurality of cylindrical pins 22 between the piston 19 and the clamp body 1. The plurality of cylindrical pins 22 are arranged at equal intervals along the circumference, and the two ends of the cylindrical pins 22 extend into the piston 19 and the clamp body 1, respectively. The clamp body 1 is provided with pin holes corresponding to the cylindrical pins 22. The length of the pin hole is greater than the length of the cylindrical pin 22 protruding from the piston 19. The cylindrical pins 22 can move axially within the pin hole, but cannot rotate around the axial direction.

[0060] Meanwhile, in this embodiment, a cylindrical pin and pin hole structure is also provided between the base 18 and the clamp body 1 to prevent relative rotation between the two. This structure is the same as the anti-rotation structure between the piston 19 and the clamp body 1, and will not be described in detail here.

[0061] In another embodiment of this application, the contact surface structure between the fixture body 1 and the expansion sleeve 2 is optimized, specifically, as follows: Figure 2 As shown, the outer circumferential end face of the part of the clamp body 1 that contacts the expansion sleeve 2 is a first conical surface that is smaller at the end closer to the expansion sleeve 2 and larger at the end farther away from the expansion sleeve 2. The inner circumferential end face of the part of the expansion sleeve 2 that contacts the clamp body 1 is a second conical surface that fits with the first conical surface that is larger at the end farther away from the pressure cap 6 and smaller at the end closer to the pressure cap 6. The outer circumferential end face of the expansion sleeve 2 is an annular curved surface with the same diameter.

[0062] The first and second conical surfaces fit together. When the expansion sleeve 2 moves axially away from the pressure cover 6, the first and second conical surfaces press against each other, forcing the expansion sleeve 2 to expand radially outward, thus clamping and fixing the inner ring of the workpiece. When the expansion sleeve 2 moves axially towards the pressure cover 6, the second conical surface gradually separates from the first conical surface. The second and first conical surfaces are no longer in close contact, and the expansion sleeve 2 is no longer subjected to the radial pressing force of the fixture body 1. The expansion sleeve 2 contracts radially, thus releasing the inner ring of the workpiece.

[0063] In practical applications, there are many ways to achieve radial expansion and contraction of the expansion sleeve 2. The above embodiment is only one feasible solution, but it is not limited to this.

[0064] In a preferred embodiment of this application, the pressure cap 6 is a floating clamping structure that can move axially. The pressure cap 6 is a structure that clamps the workpiece on the other side of its axial direction. Covering the other side of the workpiece's axial direction, the pressure cap 6 itself prevents oil, grinding mud, and grinding wheel dust from splashing to the other side, providing good protection. Simultaneously, the pressure cap 6, in conjunction with the positioning block 3, clamps the workpiece from both sides, resulting in better clamping stability. The floating pressure cap 6 allows for slight axial deviation, making assembly easier and facilitating the removal of impurities from the positioning block 3.

[0065] In actual machining of the main reduction gear, the workpiece to be machined is first placed on the expansion sleeve 2, with the inner ring of the workpiece wrapped around the expansion sleeve 2, so that the axial end face of the inner ring of the workpiece contacts the positioning block 3. The positioning boss 4 of the positioning block 3 abuts against the axial end face of the inner ring of the workpiece. The oil drain groove 7 on the positioning boss 4 corresponds one-to-one with the through hole on the inner ring, forming an interconnected relationship. The positioning boss 4 does not obstruct the through hole. The pressure cover 6, fixed on the machine tool spindle, clamps the workpiece from the other axial side of the workpiece, with the pressure cover 6 clamping the workpiece on the other axial end face of the workpiece. Then, the second oil circuit 21 is opened and the first oil circuit 20 is closed. Oil is supplied to the second oil circuit 21. The pressurized oil enters the second piston chamber through the second oil circuit 21. The pressure in the second piston chamber increases, driving the piston 19 to move axially away from the pressure cover 6. Under the drive of the piston 19, the pull rod 17 and the expansion sleeve 2 move axially away from the pressure cover 6. Under the action of the clamp body 1, the expansion sleeve 2 expands radially outward until the outer circumferential end face of the expansion sleeve 2 is tightly attached to the inner ring of the workpiece, thus completing the clamping and fixing of the workpiece. During this process, the air passage structure on the fixture body 1 and the positioning block 3 is always in the open state. High-pressure gas is introduced into the sixth air passage through the air supply equipment. The high-pressure gas enters the first air passage 10 of the fixture body 1 through the sixth air passage and the air groove. The high-pressure gas entering the first air passage 10 is divided into two paths. One path is ejected from the positioning surface of the positioning block 3 through the second air passage 11 and the third air passage 12. The ejected high-pressure gas will purge the positioning surface. The other path is ejected from the first conical surface through the fourth air passage 13 and the fifth air passage 14. During the radial expansion of the expansion sleeve 2 to clamp the inner ring of the workpiece, the push rod 15 moves radially away from the pressure plate 6, compressing the spring 16. The O-ring 23 on the push rod 15 moves to the inlet end of the fifth air passage 14 away from the pressure plate. Figure 3 As shown, the connection between the fourth air passage 13 and the fifth air passage 14 is cut off. The air tightness detection channel formed by the first air passage 10, the second air passage 11 and the third air passage 12 determines whether the expansion sleeve 2 is properly clamped to the inner ring of the workpiece. If it is properly clamped, the grinding operation can be started; otherwise, the corresponding fault needs to be eliminated. The grinding operation begins. During the grinding process, the grinding mud and grinding wheel dust generated flow between the positioning block 3 and the workpiece under the action of the grinding oil. The oil carries the grinding mud and grinding wheel dust through the through hole of the inner ring into the oil drain groove 7, and then flows into the recessed channel 5 and is thrown out along the inclined surface, or enters the axial oil drain hole 8 and is then discharged from the radial oil drain hole 9, or is directly discharged to the outside of the positioning block 3 through the radial oil drain hole 9. After the workpiece grinding is completed, the first oil passage 20 is opened and the second oil passage 21 is closed. Oil is supplied to the first oil passage 20. The chemically added oil enters the first piston chamber through the first oil passage 20. The pressure in the first piston chamber increases, pushing the piston 19 to move axially toward the pressure cover 6. Driven by the piston 19, the pull rod 17, together with the expansion sleeve 2, moves axially toward the side closer to the pressure cover 6. The expansion sleeve 2 contracts radially inward until the outer circumferential end face of the expansion sleeve 2 disengages from the inner ring of the workpiece, thus completing the loosening of the workpiece. As the expansion sleeve 2 moves axially toward the pressure cap 6, the push rod 15 moves along with the expansion sleeve 2. The spring 16 drives the push rod 15 to move axially toward the pressure cap 6 until the O-ring 23 on the push rod 15 moves to the inlet end of the fifth air passage 14 near the pressure cap 6. Figure 4 As shown, the fourth gas passage 13 and the fifth gas passage 14 are connected. The high-pressure gas provided by the gas supply equipment is ejected from the gap between the first conical surface and the second conical surface through the first gas passage 10, the fourth gas passage 13 and the fifth gas passage 14 to clean it. Complete the machining operation of a single workpiece.

[0066] In this application, "axial" refers to the axial direction of the workpiece after it is assembled onto the fixture, i.e. Figure 2 In this application, the radial direction refers to the radial direction of the workpiece after it is assembled onto the fixture, and the circumferential direction refers to the circumferential direction of the workpiece after it is assembled onto the fixture.

[0067] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A grinding fixture for the main reduction gear of an automotive gearbox, characterized in that: include, Fixture body (1); The expansion sleeve structure includes an expansion sleeve (2) that is axially movable and disposed at one axial end of the fixture body (1); the expansion sleeve (2) is an annular structure that is inserted into the inner ring of the workpiece, expands radially outward to clamp the inner ring of the workpiece when it moves to one axial side, and contracts radially inward to loosen the inner ring of the workpiece when it moves to the other axial side. The positioning block (3) is a ring structure fixed on the fixture body (1). The positioning block (3) has multiple positioning bosses (4) arranged circumferentially on the axial end face of the positioning block (3) that contacts the inner ring of the workpiece. The positioning bosses (4) are protrusions that protrude axially toward the inner ring of the workpiece for positioning the workpiece. The adjacent positioning bosses (4) are arranged at intervals to form recessed channels (5) for discharging grinding impurities. Pressure cap (6), the pressure cap (6) is fixed on the machine tool spindle and is placed on both sides of the workpiece along with the positioning block (3) to position the axial end face of the workpiece; The recessed channel (5) is an inclined surface that is higher on the side closer to the center and lower on the side farther from the center in the radial direction; an axial drain hole (8) extending in the axial direction is provided on the recessed channel (5); one axial end of the axial drain hole (8) is located on the recessed channel (5), and the other axial end is connected to the inner and outer sides of the positioning block (3) through the drain structure. The oil drain structure includes a radial oil drain hole (9); the radial oil drain hole (9) passes through the positioning block (3) radially, and the radial oil drain hole (9) is connected to the end of the axial oil drain hole (8) away from the recessed channel (5); the radial oil drain hole (9) is an inclined hole that is high on the side closer to the center of the positioning block (3) and low on the side away from the center of the positioning block (3).

2. The grinding fixture for the main reduction gear of an automotive gearbox as described in claim 1, characterized in that: The positioning boss (4) has an axially recessed oil drain groove (7) on the side facing the inner ring of the workpiece; the oil drain groove (7) is located at the radial middle position of the positioning boss (4) and the oil drain groove (7) penetrates the positioning boss (4) circumferentially.

3. The grinding fixture for the main reduction gear of an automotive gearbox as described in claim 2, characterized in that: The bottom surface of the oil drain groove (7) is an inclined surface that is higher on one side and lower on the other side along the circumference; the bottom surfaces of adjacent oil drain grooves (7) have the same inclination direction; the width of the oil drain groove (7) in the radial direction is greater than the diameter of the inner ring through hole.

4. The grinding fixture for the main reduction gear of an automotive gearbox as described in claim 1, characterized in that: A first purging structure for cleaning the positioning surface of the positioning block (3) is provided between the clamp body (1) and the positioning block (3); the first purging structure includes, The first gas passage (10) is a gas passage arranged radially on the fixture body (1); The second air passage (11) is a gas passage arranged axially on the fixture body (1). One end of the second air passage (11) is connected to the first air passage (10), and the other end extends axially to the end face of the fixture body (1) that contacts the positioning block (3). The third air passage (12) is a gas passage arranged axially on the positioning block (3). One end of the third air passage (12) is connected to one end of the second air passage (11) extending to the axial end face of the fixture body (1), and the other end extends axially to the positioning surface of the positioning block (3) that contacts the inner ring of the workpiece.

5. The grinding fixture for the main reduction gear of an automotive gearbox as described in claim 4, characterized in that: A second purging structure for cleaning the contact surfaces of the clamp body (1) and the expansion sleeve (2) is provided between them; the second purging structure includes, The fourth air passage (13) is a gas passage arranged axially on the fixture body (1). One end of the fourth air passage (13) is connected to the first air passage (10), and the other end extends axially towards the end of the fixture body (1) near the expansion sleeve (2). The fifth gas passage (14) is a gas passage arranged radially on the fixture body (1). One end of the fifth gas passage (14) is connected to the fourth gas passage (13), and the other end extends radially to the end face of the fixture body (1) that contacts the expansion sleeve (2).

6. The grinding fixture for the main reduction gear of an automotive gearbox as described in claim 5, characterized in that: An airtightness detection structure for determining whether the expansion sleeve (2) has moved axially into place is provided between the fourth air passage (13) and the fifth air passage (14); the airtightness detection structure includes, Push rod (15), the push rod (15) is a rod-shaped structure with one end axially inserted into the fourth air passage (13) near the end of the expansion sleeve (2), and the other end of the push rod (15) is fixedly connected to the expansion sleeve (2). When the push rod (15) moves axially with the expansion sleeve (2) to coincide with the fifth air passage (14) in the axial direction, it cuts off the connection between the fourth air passage (13) and the fifth air passage (14). When the push rod (15) moves axially with the expansion sleeve (2) to not coincide with the fifth air passage (14) in the axial direction, it connects the fourth air passage (13) and the fifth air passage (14). Spring (16), one end of which is fixed to the end of the push rod (15) away from the expansion sleeve (2), and the other end is fixed in the fourth air passage (13).

7. The grinding fixture for the main reduction gear of an automotive gearbox as described in claim 1, characterized in that: The expansion sleeve structure includes, A pull rod (17) is axially inserted through the clamp body (1) and coaxially arranged with the clamp body (1). One end of the pull rod (17) is fixedly connected to the expansion sleeve (2). The base (18) is fixed to the end of the clamp body (1) away from the expansion sleeve (2); Piston (19), the piston (19) is axially movable and is disposed in the clamp body (1). A first piston chamber is formed between the piston (19) and the base (18) on one axial side, and a second piston chamber is formed between the piston (19) and the clamp body (1) on the other axial side. The piston (19) is fixedly connected to the other end of the pull rod (17). The first oil passage (20) is located on the base (18) and is connected to the first piston chamber for injecting oil into the first piston chamber to drive the piston (19) to move axially toward the side closer to the expansion sleeve (2). The second oil passage (21) is located on the base (18) and the fixture body (1). The second oil passage (21) is connected to the second piston chamber and is used to inject oil into the second piston chamber to drive the piston (19) to move axially away from the expansion sleeve (2).

8. The grinding fixture for the main reduction gear of an automotive gearbox as described in claim 7, characterized in that: The outer circumferential end face of the part of the clamp body (1) that contacts the expansion sleeve (2) is a first conical surface that is smaller at the end closer to the expansion sleeve (2) and larger at the end farther away from the expansion sleeve (2); the inner circumferential end face of the part of the expansion sleeve (2) that contacts the clamp body (1) is a second conical surface that fits the first conical surface that is larger at the end farther away from the pressure cap (6) and smaller at the end closer to the pressure cap (6); the outer circumferential end face of the expansion sleeve (2) is an annular curved surface with the same diameter.

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