Internal thread precision grinding device based on liquid expansion tooling

Abstract

This application discloses a precision grinding device for internal threads based on a hydraulic expansion fixture, relating to the field of nut grinding. It includes a base with an oil groove fixed on it, an automatic grinding device mounted on the base, a worktable installed in the oil groove, and a shim and chuck mounted on the worktable. This application uses a drive shaft to drive the hydraulic expansion fixture via a coupling, causing the thread grinding sleeve to rotate. The thread grinding sleeve engages with the internal thread of the nut. Grinding of the internal thread can be performed by controlling the forward and reverse rotation of a servo motor. When the hydraulic oil pressure in the hydraulic fixture chamber increases, it causes the thin-walled elastic expansion and radial deformation, thereby causing the thread grinding sleeve to expand radially. When the linear cylinder pushes in, the servo motor load reaches a preset value, and the linear cylinder maintains this pressure value until the remaining internal thread material is processed. Therefore, it can improve the product qualification rate and achieve higher precision.

Description

Technical Field

[0001] This application relates to the field of nut grinding, and more particularly to a precision grinding apparatus for internal threads based on a hydraulic expansion fixture. Background Technology

[0002] Planetary roller screw mechanisms are rolling helical transmission mechanisms that convert linear and rotary motion into each other. They transmit power through multi-point threaded contact between multiple rollers and the screw and nut raceways. The transmission mechanism consists of a screw, nut, and rollers. The rollers simultaneously mesh with the screw thread and the internal gear ring of the nut. It features a large number of contact points, high load-bearing capacity, and long service life, and is often used in aerospace, shipbuilding, intelligent manufacturing, and weaponry.

[0003] In existing reverse planetary roller screws, the nut is a crucial component affecting transmission error and efficiency. Its thread profile error and pitch error are very important indicators. The nut is characterized by its long thread length, with a length-to-diameter ratio of 15 to 20 times the diameter. Traditionally, internal thread machining is mainly done by internal thread grinding. However, when the thread length-to-diameter ratio exceeds three times the diameter, the grinding rod will interfere with the workpiece, requiring the use of interference grinding or bent rod grinding, which has very low processing efficiency and extremely high cost. Furthermore, the thread pitch diameter is prone to taper during the machining process, leading to poor product assembly. Therefore, in order to improve the product qualification rate and obtain higher precision, thread grinding is necessary. Utility Model Content

[0004] To improve product qualification rate and achieve higher precision, this application provides a precision grinding device for internal threads based on a hydraulic expansion fixture.

[0005] The technical solution of the precision grinding device for internal threads based on hydraulic expansion fixture provided in this application is as follows: a precision grinding device for internal threads based on hydraulic expansion fixture includes a base, an oil groove fixed on the base, an automatic grinding device on the base, a worktable installed in the oil groove, and a shim and a chuck installed on the worktable.

[0006] The automatic grinding device includes a vertical plate, guide rail, mounting plate, servo motor, balance cylinder, linear cylinder, bearing seat, coupling, hydraulic expansion fixture, and thread grinding sleeve.

[0007] The mounting plate is slidably mounted on the back of the mounting plate via a slider and a guide rail. A motor bracket and a hydraulic cylinder bracket are fixedly mounted on the front of the mounting plate. The servo motor is fixedly mounted on the motor bracket, and the linear hydraulic cylinder is fixedly mounted on the hydraulic cylinder bracket. One of the synchronous pulleys is fixedly mounted on the output end of the servo motor, and the other synchronous pulley is fixedly mounted on the bearing seat. A synchronous belt is connected to the two synchronous pulleys. A first connector and a second connector are fixedly mounted on the side of the mounting plate, and the balance cylinder is installed between the first connector and the second connector.

[0008] The bearing housing contains a bearing, one end of which is fixedly mounted with a drive shaft, and the coupling is fixedly mounted to the lower end of the drive shaft.

[0009] By adopting the above technical solution, the servo motor is rotated by the control system. The servo motor transmits motor torque through the synchronous pulley and synchronous belt, which drives the drive shaft to rotate. The drive shaft drives the hydraulic expansion fixture through the coupling to make the thread grinding sleeve rotate. The thread grinding sleeve meshes with the internal thread of the nut. The internal thread can be ground by controlling the forward and reverse rotation of the servo motor.

[0010] Preferably, the hydraulic expansion fixture is connected to the other end of the coupling. The hydraulic expansion fixture is provided with an expansion oil chamber and a cylinder. The cylinder is equipped with a piston rod, a piston plug seal, a piston cap, and a return spring. The output shaft of the linear cylinder is fixedly connected to an external piston push rod.

[0011] By adopting the above technical solution, when the grinding reaches a certain level, the load of the servo motor is lower than the preset value. The linear cylinder will continue to pressurize and push the piston rod. The piston rod pushes the piston rod of the hydraulic tooling, which increases the hydraulic oil pressure in the hydraulic tooling chamber, causing the thin wall elastic expansion to cause radial deformation. This, in turn, causes the thread grinding sleeve to expand radially. When the load of the servo motor reaches the preset value during the linear cylinder's push-in process, the linear cylinder will maintain this pressure value until the internal thread allowance is processed. Therefore, the product qualification rate can be improved and higher precision can be obtained.

[0012] Preferably, the thread grinding sleeve is located at the lower end of the hydraulic expansion fixture, and a stop end and a hand-tightening bolt are installed inside the hydraulic expansion fixture.

[0013] By adopting the above technical solution, the installation can be assisted by setting a stop end and a hand-tightening bolt.

[0014] Preferably, the bearing housing is provided with a round nut.

[0015] By adopting the above technical solution, a round nut can be used to assist in the installation.

[0016] Preferably, a housing is fixedly installed on one side of the oil tank, and a screw is rotatably installed inside the housing. Two sliding blocks are symmetrically screwed onto the screw. The screw has a bidirectional thread. A corresponding sealing plate is fixedly installed on one side of each of the two sliding blocks. A drive motor is fixedly installed on one side of the housing, and the output end of the drive motor is fixedly installed to one end of the screw.

[0017] By adopting the above technical solution, the output of the drive motor is controlled to rotate the screw. The rotation of the screw will cause the two sliding blocks and the two sealing plates to move closer to each other, thereby assembling the two sealing plates and sealing the top of the oil tank. Furthermore, the through hole in the middle of the two sealing plates will not affect the normal use of the thread grinding sleeve. This sealing treatment can reduce the amount of external impurities and dust falling into the oil tank, thus preventing a large amount of dust from entering the oil tank and affecting the performance of the grinding oil.

[0018] Preferably, the side of the housing closest to the oil tank is open, and a through hole is provided in the middle of the two sealing plates, with an oil pipe provided on one of the sealing plates.

[0019] By adopting the above technical solution, grinding oil can be added during use via an oil pipe.

[0020] Preferably, a drain pipe is fixedly installed through one side of the oil tank.

[0021] By adopting the above technical solution, the opening and closing of the drain pipe can be controlled by the valve on the drain pipe, and the grinding lubricating oil inside the oil tank can be discharged.

[0022] In summary, this application includes at least one of the following beneficial technical effects:

[0023] 1. This application employs a linear hydraulic cylinder and the like, which drives a rotating shaft via a coupling to drive a hydraulic expansion fixture, causing the thread grinding sleeve to rotate. The thread grinding sleeve engages with the internal thread of the nut. The grinding of the internal thread can be performed by controlling the forward and reverse rotation of a servo motor. When the hydraulic oil pressure in the hydraulic fixture chamber increases, it causes the thin-walled elastic expansion and radial deformation, which in turn causes the thread grinding sleeve to expand radially. When the load of the servo motor reaches a preset value during the pushing process of the linear hydraulic cylinder, the linear hydraulic cylinder will maintain this pressure value until the remaining internal thread is processed. Therefore, the product qualification rate can be improved and higher precision can be obtained.

[0024] 2. This application utilizes the cooperation of sealing plates, etc., to control the start of the drive motor. The output end of the drive motor drives the screw to rotate. The rotation of the screw drives the two sliding blocks and the two sealing plates to move closer to each other, thereby assembling the two sealing plates and sealing the top of the oil tank. Furthermore, the through hole in the middle of the two sealing plates does not affect the normal use of the thread grinding sleeve. It further seals the oil tank and reduces the amount of external impurities and dust falling into it. Therefore, it can prevent a lot of dust from entering the oil tank and affecting the performance of the grinding oil. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of a precision grinding device for internal threads based on a hydraulic expansion fixture, according to an embodiment of this application.

[0026] Figure 2 This is a schematic diagram illustrating the main processing structure of the embodiments of this application;

[0027] Figure 3 This is a cross-sectional schematic diagram illustrating the main processing structure in the embodiments of this application;

[0028] Figure 4 This is a schematic diagram illustrating the internal structure of the oil tank, representing a key embodiment of this application.

[0029] Figure 5 This is a schematic diagram illustrating the main driving structure in the embodiments of this application;

[0030] Figure 6 This is a schematic diagram illustrating the connection structure of the embodiments of this application;

[0031] Figure 7 This is a schematic diagram illustrating the dustproof structure, which is a key feature of this application's embodiments.

[0032] Reference numerals: 1. Base; 2. Oil tank; 3. Vertical plate; 4. Guide rail; 5. Mounting plate; 6. First connector; 7. Balance cylinder; 8. Second connector; 9. Cylinder bracket; 10. Linear cylinder; 11. Synchronous pulley; 12. Synchronous belt; 13. Motor bracket; 14. Servo motor; 15. Bearing seat; 16. Coupling; 17. Worktable; 18. Bearing; 19. Round nut; 20. Drive shaft; 21. Hydraulic expansion fixture; 22. Elevating block; 23. Chuck; 24. Piston rod; 25. Piston plug seal; 26. Piston cap; 27. Return spring; 28. Stop end; 29. ​​Hand-tightening bolt; 30. Sealing plate; 31. Oil pipe; 32. Housing; 33. Drain pipe; 34. Screw; 35. Sliding block; 36. Drive motor; 37. Thread grinding sleeve. Detailed Implementation

[0033] The following is in conjunction with the appendix Figures 1-7This application will be described in further detail.

[0034] This application discloses an internal thread precision grinding apparatus based on a hydraulic expansion fixture.

[0035] Reference Figure 1-3 A precision grinding device for internal threads based on a hydraulic expansion fixture includes a base 1, an oil tank 2 fixed on the base, an automatic grinding device on the base 1, a worktable 17 installed in the oil tank 2, a shim block 22 and a chuck 23 installed on the worktable 17, and a dustproof mechanism set on the oil tank 2.

[0036] The automatic grinding device includes a vertical plate 3, a guide rail 4, a mounting plate 5, a servo motor 14, a balance cylinder 7, a linear cylinder 10, a bearing seat 15, a coupling 16, a hydraulic expansion fixture 21, and a thread grinding sleeve 37.

[0037] The back of the mounting plate 5 is slidably mounted to the guide rail 4 via a slider. The front of the mounting plate 5 is fixedly mounted with a motor bracket 13 and a hydraulic cylinder bracket 9. The servo motor 14 is fixedly mounted on the motor bracket 13, and the linear hydraulic cylinder 10 is fixedly mounted on the hydraulic cylinder bracket 9. One of the synchronous pulleys 11 is fixedly mounted on the output end of the servo motor 14, and the other synchronous pulley 11 is fixedly mounted on the bearing seat 15. The two synchronous pulleys 11 are connected to a synchronous belt 12. The first connector 6 and the second connector 8 are fixedly mounted on the side of the mounting plate 5. The balance cylinder 7 is installed in the middle of the first connector 6 and the second connector 8.

[0038] The bearing 18 is installed in the bearing housing 15, and a drive shaft 20 is fixedly installed at one end of the bearing 18. The coupling 16 is fixedly installed at the lower end of the drive shaft 20.

[0039] In use, the servo motor 14 is rotated by the control system. The servo motor 14 transmits motor torque through the synchronous pulley 11 and the synchronous belt 12, which drives the drive shaft 20 to rotate. The drive shaft 20 drives the hydraulic expansion fixture 21 through the coupling 16 to make the thread grinding sleeve 37 rotate. The thread grinding sleeve 37 engages with the internal thread of the nut. The internal thread can be ground by controlling the forward and reverse rotation of the servo motor 14.

[0040] Reference Figure 4-6 The hydraulic expansion fixture 21 is connected to the other end of the coupling 16. The hydraulic expansion fixture 21 is provided with an expansion oil chamber and a cylinder. The cylinder is equipped with a piston rod 24, a piston plug seal 25, a piston cap 26, and a return spring 27. The output shaft of the linear cylinder 10 is fixedly connected to the external piston push rod. The threaded grinding sleeve 37 is located at the lower end of the hydraulic expansion fixture 21. The hydraulic expansion fixture 21 is equipped with a stop end 28 and a hand-tightening bolt 29. The bearing seat 15 is provided with a round nut 19.

[0041] During use, after grinding to a certain extent, the load of the servo motor 14 is lower than the preset value. The linear cylinder 10 will continue to pressurize and push the piston rod. The piston rod pushes the hydraulic tool piston rod 24, which increases the hydraulic oil pressure in the hydraulic tool chamber, causing the thin wall elastic expansion to cause radial deformation. This, in turn, causes the thread grinding sleeve 37 to expand radially. When the load of the servo motor 14 reaches the preset value during the pushing process of the linear cylinder 10, the linear cylinder 10 will maintain this pressure value until the internal thread allowance is processed. Therefore, it can improve the product qualification rate and obtain higher precision. This grinding device has a simple structure, replaceable thread grinding sleeve, convenient operation, and can meet the requirements of high-precision thread grinding.

[0042] Reference Figure 1 and Figure 7 The dustproof mechanism includes a housing 32 fixedly installed on one side of the oil tank 2. A screw 34 is rotatably installed inside the housing 32. Two sliding blocks 35 are symmetrically screwed onto the screw 34. The screw 34 has a bidirectional thread. A corresponding sealing plate 30 is fixedly installed on one side of each of the two sliding blocks 35. A drive motor 36 is fixedly installed on one side of the housing 32. The output end of the drive motor 36 is fixedly installed at one end of the screw 34.

[0043] In use, by controlling the start of the drive motor 36, the output end of the drive motor 36 will drive the screw 34 to rotate. The rotation of the screw 34 will drive the two sliding blocks 35 and the two sealing plates 30 to move closer to each other, so that the two sealing plates 30 can be assembled and seal the top of the oil tank 2. Furthermore, the middle position of the two sealing plates 30 has a through hole, which will not affect the normal use of the thread grinding sleeve 37. It can further seal the oil tank 2 and reduce the amount of external impurities and dust falling into the oil tank 2. Therefore, it can prevent a lot of dust from entering the oil tank 2 and affecting the effect of the grinding oil.

[0044] Reference Figure 1 and Figure 7 The side of the housing 32 closest to the oil tank 2 is open. A through hole is provided in the middle of the two sealing plates 30. The width of the through hole is greater than the width of the threaded grinding sleeve 37, so there will be no movement interference. An oil pipe 31 is provided on one of the sealing plates 30. A drain pipe 33 is fixedly installed on one side of the oil tank 2. A valve is provided on the drain pipe 33.

[0045] During use, grinding oil can be added through oil pipe 31, and the opening and closing of drain pipe 33 can be controlled by valve on drain pipe 33, and the grinding lubricating oil inside oil tank 2 can be discharged.

[0046] The installation method of the chuck 23 in this application is prior art, so the specific installation and use process is not described in detail. The control system described in this application adopts prior art, so the specific control and installation and use process is not described in detail. Furthermore, all electronic devices in this application are connected, installed and used using prior art.

[0047] The implementation principle of the internal thread precision grinding device based on hydraulic expansion tooling in this application embodiment is as follows: When in use, firstly, the oil tank 2 is fixed on the base 1, and the worktable 17 is installed in the oil tank 2; the shim block 22 and chuck 23 are installed and fixed on the worktable 17; at this time, the nut to be ground is installed in the chuck 23 in the oil tank 2 and clamped; by installing the bearing 18 in the bearing seat 15, the drive shaft 20 is inserted through the middle of the bearing 18; at this time, the round nut 19 is screwed into the thread below the drive shaft 20 and tightened; the drive synchronous pulley 11 is installed through the output shaft of the servo motor 14; the piston push rod is inserted from the center of the drive shaft 20 and connected to the linear cylinder 10; then another synchronous pulley 11 is installed on the upper end of the drive shaft 20; and the synchronous belt 12 is connected to the two synchronous pulleys 11.

[0048] At this time, the return spring 27 is installed inside the hydraulic expansion fixture 21, the piston plug seal 25 is installed on the piston rod 24, the piston cap 26 is fastened on the piston rod 24, and the piston assembly is installed inside the hydraulic expansion fixture 21. At this time, the thread grinding sleeve 37 is installed on the expansion end of the hydraulic expansion fixture 21, and then the stop end 28 is inserted and fixed with the hand-tightening bolt 29.

[0049] By installing one end of the coupling 16 on the drive shaft 20 and connecting the other end to the hydraulic expansion fixture 21, and making the piston push rod contact the piston rod 24, the oil tank 2 is filled with grinding oil and abrasive. Then, the assembled grinding device is manually pushed gently into the nut on the chuck 23 by the guide part of the threaded grinding sleeve 37.

[0050] Subsequently, the control system is used to rotate the servo motor 14. The servo motor 14 transmits motor torque through the drive synchronous pulley 11 and synchronous belt 12, which drives the drive shaft 20 to rotate. The drive shaft 20 drives the hydraulic expansion fixture 21 through the coupling 16 to make the thread grinding sleeve 37 rotate. The thread grinding sleeve 37 engages with the internal thread of the nut. The internal thread can be ground by controlling the forward and reverse rotation of the servo motor 14.

[0051] When the grinding reaches a certain level, the load on the servo motor 14 is lower than the preset value. The linear cylinder 10 will continue to pressurize and push the piston rod. The piston rod pushes the hydraulic tooling piston rod 24, which increases the hydraulic oil pressure in the hydraulic tooling chamber, causing the thin wall elastic expansion to cause radial deformation. This, in turn, causes the thread grinding sleeve 37 to expand radially. When the load on the servo motor 14 reaches the preset value during the pushing process of the linear cylinder 10, the linear cylinder 10 will maintain this pressure value until the internal thread allowance is processed. Therefore, the product qualification rate can be improved and higher precision can be obtained.

[0052] By controlling the start of the drive motor 36, the output of the drive motor 36 will drive the screw 34 to rotate. The rotation of the screw 34 will drive the two sliding blocks 35 and the two sealing plates 30 to move closer to each other, thereby allowing the two sealing plates 30 to assemble and seal the top of the oil tank 2. Furthermore, the through hole in the middle of the two sealing plates 30 will not affect the normal use of the thread grinding sleeve 37. This further seals the oil tank 2 and reduces the amount of external impurities and dust falling into it, thus preventing a lot of dust from entering the oil tank 2 and affecting the performance of the grinding oil.

[0053] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A precision grinding apparatus for internal threads based on a hydraulic expansion fixture, characterized in that: Includes a base (1), on which an oil tank (2) is fixed, and an automatic grinding device is provided on the base (1). A worktable (17) is installed in the oil tank (2), and a shim (22) and a chuck (23) are installed on the worktable (17). The automatic grinding device includes a vertical plate (3), a guide rail (4), a mounting plate (5), a servo motor (14), a balance cylinder (7), a linear cylinder (10), a bearing seat (15), a coupling (16), a hydraulic expansion fixture (21), and a thread grinding sleeve (37). The mounting plate (5) is slidably mounted on the back side by a slider and the guide rail (4). The front side of the mounting plate (5) is fixedly mounted with a motor bracket (13) and a cylinder bracket (9). The servo motor (14) is fixedly mounted on the motor bracket (13). The linear cylinder (10) is fixedly mounted on the cylinder bracket (9). One of the synchronous pulleys (11) is fixedly mounted on the output end of the servo motor (14). Another synchronous pulley (11) is fixedly mounted on the bearing seat (15). The two synchronous pulleys (11) are connected by a synchronous belt (12). The side of the mounting plate (5) is fixedly mounted with a first connector (6) and a second connector (8). The balance cylinder (7) is installed in the middle position between the first connector (6) and the second connector (8). The bearing housing (15) contains a bearing (18), and a drive shaft (20) is fixedly installed at one end of the bearing (18). The coupling (16) is fixedly installed at the lower end of the drive shaft (20).

2. The internal thread precision grinding device based on a hydraulic expansion fixture according to claim 1, characterized in that: The hydraulic expansion fixture (21) is connected to the other end of the coupling (16). The hydraulic expansion fixture (21) is provided with an expansion oil chamber and an oil cylinder. The oil cylinder is equipped with a piston rod (24), a piston plug seal (25), a piston cap (26), and a return spring (27). The output shaft of the linear oil cylinder (10) is fixedly connected to the external piston push rod.

3. The internal thread precision grinding device based on a hydraulic expansion fixture according to claim 2, characterized in that: The thread grinding sleeve (37) is located at the lower end of the hydraulic expansion fixture (21), and the hydraulic expansion fixture (21) is equipped with a stop end (28) and a hand-tightening bolt (29).

4. The internal thread precision grinding device based on a hydraulic expansion fixture according to claim 1, characterized in that: A round nut (19) is provided on the bearing housing (15).

5. The precision grinding apparatus for internal threads based on a hydraulic expansion fixture according to claim 1, characterized in that: A housing (32) is fixedly installed on one side of the oil tank (2). A screw (34) is rotatably installed inside the housing (32). Two sliding blocks (35) are symmetrically screwed onto the screw (34). The screw (34) is bidirectionally threaded. A corresponding sealing plate (30) is fixedly installed on one side of each of the two sliding blocks (35). A drive motor (36) is fixedly installed on one side of the housing (32). The output end of the drive motor (36) is fixedly installed to one end of the screw (34).

6. The internal thread precision grinding device based on a hydraulic expansion fixture according to claim 5, characterized in that: The side of the housing (32) near the oil tank (2) is open, and a through hole is provided in the middle of the two sealing plates (30), and an oil pipe (31) is provided on one of the sealing plates (30).

7. The internal thread precision grinding device based on a hydraulic expansion fixture according to claim 1, characterized in that: A drain pipe (33) is fixedly installed on one side of the oil tank (2).

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