Integrated lead screw bearing inner ring channel superfinishing equipment

Abstract

The utility model relates to an integrated lead screw bearing inner ring channel superfinishing device, which relates to the technical field of bearing processing, and comprises a left centering seat and a right centering seat which are used for clamping a workpiece, the right centering seat is connected with a supporting shaft through an angular contact ball bearing, and the outer diameter of the angular contact ball bearing is in interference fit with the large inner hole surface of the right centering seat. The end face of the outer ring of the angular contact ball bearing makes close contact with the inner end face of the right centering base so that the workpiece and the right centering base can rotate synchronously. The utility model is favorable for solving the problem that the inner ring of the integrated screw rod bearing cannot be superfinely integrated by adopting a conventional superfinishing machine tool; the apparent quality of the bearing is improved; the workpiece precision is improved; the production efficiency is improved; the centering device is simple in structure and can be popularized for inner groove superfinishing of other similar bearings.

Description

Technical Field

[0001] This utility model relates to ultra-precision machining equipment for the inner ring groove of integrated ball screw bearings, and belongs to the field of bearing processing technology. In particular, it relates to ultra-precision machining of the inner ring groove of integrated ball screw bearings for humanoid robots and four-point contact ball bearings for integrated ball screws in steering systems. The ultra-precision method is a practical technology for ultra-precision machining of the inner ring groove of integrated ball screw bearings. Background Technology

[0002] Integrated ball screw bearings for humanoid robots feature a design that integrates the bearing and ball screw into one unit. This integrated bearing is a double-row angular contact ball bearing or a four-point contact bearing. The bearing inner ring has a relatively high height, and the inner groove is integrated on one side of the inner ring, creating an asymmetrical structure. The outer diameter of the inner ring consists of multiple segments with different outer diameters connected together. The inner ring bore is a ball screw nut or roller screw nut with a circulating structure. This structure offers advantages such as high transmission efficiency, accurate positioning, and long service life. During ultra-precision machining of the bearing, the workpiece can be clamped using the following methods: mechanical clamping centerless clamping, double roller clamping, and hydraulic centering clamping.

[0003] 1. Mechanical clamping type centerless clamping fixture

[0004] like Figure 1 As shown, during clamping, the outer diameter and reference end face are used for positioning, and two clamping wheels are used to press the end face. The fixed supports are symmetrically distributed on both sides below the workpiece, with support angles ranging from 100° to 120°, eccentrically positioned on the horizontal center line. Electromagnetic centerless clamps are not used, thus completely avoiding a series of adverse effects caused by the use of magnetic force. However, it also has some problems, such as the ultra-precision groove being positioned by the outer diameter, whose machining accuracy is affected by the geometric shape error of the outer diameter; the workpiece rotation speed is limited and cannot be too high, otherwise it may cause burning of the end face or outer diameter surface; the original parallelism difference between the groove and the reference end face cannot be too large, otherwise the machining quality will be unstable. Because the supports are on the outer diameter or groove of the product, support marks or scratches on the contact surface are easily generated. The ultra-precision groove is positioned by the end face and outer diameter, whose machining accuracy is affected by the geometric shape error of the outer diameter; the workpiece rotation speed is limited and cannot be too high, otherwise it may cause burning of the end face or outer diameter surface; the original parallelism difference between the groove and the reference end face cannot be too large, otherwise the machining quality will be unstable. The bearing inner ring is too high, resulting in large radial runout and unstable rotation after the end face is pressed together.

[0005] 2. Double roller clamping

[0006] like Figure 2As shown, in this method, the bearing ring is placed directly between two rollers, and an oilstone presses the ring against the rollers from top to bottom. The friction between the workpiece and the rollers drives the workpiece to rotate. The angle α between the workpiece center and the line connecting the centers of the two rollers is generally taken as 140° to 150°. In actual adjustment, the support angle α is maintained by changing the distance between the two rollers. This mechanism has a simple structure and is easy to adjust, but it lacks an end-face centering device, and the power transmission relies solely on the friction of the outer circular surface, which is prone to slippage and axial movement. Therefore, it is difficult to guarantee the positional accuracy of the groove. Without an end-face centering device, the power transmission relies solely on the friction of the outer circular surface, which is prone to slippage. The bearing inner ring is relatively high and has an asymmetrical structure. The outer diameter of the bearing inner ring consists of multiple segments with different outer diameters connected together, resulting in unstable rotation and axial movement. Therefore, it is difficult to guarantee the accuracy of the groove.

[0007] 3. Hydraulic centering clamping

[0008] (1) Inner sleeve hydraulic centering clamping

[0009] Figure 3 As shown, the workpiece is placed between a rotating end face support and two floating clamping rollers, and rotates due to the friction between them. The hydraulic oil in the hydraulic centering shaft suspends the workpiece on the shaft, creating pure liquid friction. Because the inner centering shaft is fixed and does not rotate with the workpiece, factors such as the hydraulic oil filtration system and the stability of the hydraulic components can affect the normal operation of ultra-precision machining, causing the centering shaft to scratch the inner surface of the workpiece and produce black marks. The pressure balance is lost during support, which also damages the original geometry of the grooved hole. Since this mechanism uses rollers to clamp the workpiece end face, wear of the pressure rollers easily leads to deep marks on the workpiece end face. Furthermore, when ultra-grinding thin-walled workpieces, the narrow end face of the workpiece easily causes premature wear of the pressure roller contact surface, affecting workpiece accuracy. The inner hole of the bearing inner ring is a ball screw nut or roller screw nut. An inner sleeve hydraulic centering clamping method is not suitable.

[0010] (2) Fixed internal support centering clamping

[0011] When using a fixed inner support to support the inner diameter of a bearing inner ring during ultra-precision machining of the inner ring raceway, a ceramic block bonded to the surface of the inner support, extending deep into the workpiece's inner bore, contacts the inner bore surface. Rotation of the inner ring relative to the inner support will cause varying degrees of scratches or blackening on the inner diameter surface. The inner bore of the bearing inner ring is typically a ball screw nut or roller screw nut. Therefore, a fixed inner support centering clamping method is not suitable.

[0012] In summary, the above methods cannot achieve ultra-precision machining of the inner ring groove of integrated ball screw bearings on conventional equipment. Utility Model Content

[0013] The purpose of this invention is to provide an ultra-precision machining device for the inner ring groove of an integrated ball screw bearing for humanoid robots, so as to achieve efficient ultra-precision machining.

[0014] To achieve the above objectives, the present invention provides an integrated ball screw bearing inner ring groove ultra-precision machining equipment, including a left centering seat and a right centering seat for clamping the workpiece. The right centering seat is connected to a support shaft via an angular contact ball bearing. The outer diameter of the angular contact ball bearing is interference-fitted with the large inner hole surface of the right centering seat. The outer ring end face of the angular contact ball bearing is in close contact with the inner end face of the right centering seat, so that the workpiece and the right centering seat can rotate synchronously.

[0015] Preferably, the angular contact ball bearing is mounted on the support shaft, the inner bore of the angular contact ball bearing is interference-fitted with the small outer diameter of the support shaft, and the bearing end face is in close contact with the bearing positioning end face of the support shaft without any gap.

[0016] Preferably, a spacer ring is provided on the inner side of the large inner hole surface of the right centering seat.

[0017] Preferably, the locking screw is inserted into the inner hole of the spacer and screwed into the MC threaded hole of the support shaft, so that the large inner hole end face of the spacer abuts against the inner ring end face of the angular contact ball bearing to ensure no clearance.

[0018] Preferably, the centering angle α conical surface at one end of the workpiece is in contact with the centering angle β conical surface of the left centering seat.

[0019] Preferably, the centering angle α conical surface at the other end of the workpiece is in contact with the centering angle γ conical surface of the right centering seat.

[0020] Preferably, the initial tilt angle of the oscillating head can be adjusted to 25°, 30° or 40° according to the required contact angle of the workpiece.

[0021] The technical solution of this utility model also provides a method for ultra-precision machining of the inner ring groove of an integrated ball screw bearing, including the following steps:

[0022] Install the centering shaft of the left centering seat into the corresponding positioning hole of the ultra-precision equipment, and tighten it with the screw through the locking screw hole MA of the left centering seat, so that the positioning end face of the left centering seat is close to the positioning hole end face of the equipment.

[0023] Install the support shaft centering round shaft of the right centering device into the corresponding positioning hole of the ultra-precision equipment, ensuring that the support shaft positioning groove of the support shaft is aligned with the direction of the pin on the equipment; tighten the support shaft with the screw through the locking screw hole MB of the support shaft, so that the support shaft positioning end face of the support shaft is close to the positioning hole end face of the equipment;

[0024] Measure the radial runout of the conical surfaces of the left and right centering seats to ensure that the radial runout is controlled within a certain range to guarantee machining accuracy;

[0025] Adjust the equipment to ensure that the accuracy and appearance quality of the workpiece meet the requirements of the drawing, and ensure that all equipment functions are normal; switch the equipment to automatic mode and prepare to start processing;

[0026] The workpiece is pushed into the ultra-precision machining area. The transmission mechanism on the right side of the equipment drives the right centering device to move, so that the centering angle γ conical surface of the right centering seat contacts the centering angle α conical surface of the workpiece. The workpiece is pushed so that the centering angle α conical surface on the other side contacts and presses against the centering angle β conical surface of the left centering seat to ensure no axial clearance.

[0027] The rotating mechanism of the equipment drives the left centering seat to rotate the workpiece. The ultra-precision swivel head is automatically fed to the ultra-precision position to perform ultra-precision machining of the groove. After the machining is completed, the ultra-precision swivel head is withdrawn, the transmission mechanism on the right side of the equipment drives the right centering device to return to its original position, the robot arm withdraws and unloads the workpiece, and the previous step is repeated to enter the ultra-precision machining of the next workpiece, and so on.

[0028] After the groove on one side of the workpiece is ultra-precision machined, it enters another ultra-precision station and performs ultra-precision machining on the groove on the other side of the workpiece according to the above steps.

[0029] In summary, this utility model has the following beneficial technical effects:

[0030] 1. Solved the problem that conventional ultra-precision machine tools cannot achieve ultra-precision integration of the inner ring of the lead screw bearing.

[0031] 2. Improved bearing appearance quality

[0032] (1) The centering devices on both sides rotate synchronously with the workpiece, avoiding scratches, marks, and black marks on the inner surface of the workpiece.

[0033] (2) Avoids scratches caused by the pressure roller (bearing) pressing the end face of the workpiece.

[0034] 3. Improved workpiece precision.

[0035] (1) Using the pin hole as the machining reference reduces the error caused by friction and the runout caused by the end face pressure roller, thus improving the machining accuracy of the bearing (such as roundness, appearance, and contour).

[0036] 4. Improved production efficiency.

[0037] (1) It makes adjustment convenient and can realize simultaneous processing of the left and right sides of the over-grinding station.

[0038] 5. Versatility.

[0039] (1) The centering device has a simple structure and can be promoted to other similar bearings for internal groove ultra-precision. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a mechanically clamping centerless clamp.

[0041] Figure 2 This is a schematic diagram of a double-roller clamping system;

[0042] Figure 3 It is a hydraulic centering clamping device for the inner sleeve;

[0043] Figure 4 This is a main sectional view of the workpiece in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model;

[0044] Figure 5 This is a left view of the workpiece in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model;

[0045] Figure 6 This is a main sectional view of the workpiece during ultra-precision machining in the integrated ball screw bearing inner ring groove ultra-precision machining equipment of this utility model;

[0046] Figure 7 This is a main sectional view of the left groove of the workpiece in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model;

[0047] Figure 8 This is a main sectional view of the right groove of the workpiece in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model;

[0048] Figure 9 This is a right view of the left centering seat in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model;

[0049] Figure 10 This is a front sectional view of the left centering seat in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model;

[0050] Figure 11 This is a front sectional view of the right centering device in the integrated ball screw bearing inner ring groove ultra-precision machining equipment of this utility model;

[0051] Figure 12 This is a right view of the right centering device in the integrated ball screw bearing inner ring groove ultra-precision machining equipment of this utility model;

[0052] Figure 13 This is a left view of the right centering device in the integrated ball screw bearing inner ring groove ultra-precision machining equipment of this utility model;

[0053] Figure 14 This is a front sectional view of the right centering seat in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model;

[0054] Figure 15 This is a main sectional view of the support shaft in the ultra-precision machining equipment for the inner ring groove of the integrated ball screw bearing of this utility model.

[0055] Reference numerals: 1. Left centering seat; 2. Workpiece; 3. Oilstone; 4. Locking screw; 5. Spacer; 6. Right centering seat; 7. Angular contact ball bearing; 8. Support shaft; 01. Double groove; 02. Left centering seat mounting auxiliary hole; 03. Left centering seat centering round shaft; 04. Left centering seat positioning end face; MA. Left centering seat locking screw hole; 05. Support shaft positioning end face; 06. Support shaft centering round shaft; 07. Support shaft positioning groove; MB. Support shaft locking screw hole; 08. Support shaft small outer diameter; 09. Support shaft bearing positioning end face; MC. Spacer locking screw hole; 10. Right centering seat inner end face; 11. Right centering seat large inner hole face. Detailed Implementation

[0056] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0057] Example 1:

[0058] This utility model discloses an integrated ultra-precision machining equipment for the inner ring groove of a lead screw bearing. This utility model achieves highly efficient ultra-precision machining by employing a combination of a left centering seat 1, a workpiece 2, and a right centering device. The specific structure is as follows: Figure 6 As shown.

[0059] 1. Integrated ball screw bearing inner ring groove ultra-precision machining equipment:

[0060] Workpiece 2 Structure: The inner ring of the integrated ball screw bearing (Workpiece 2) is an elongated ring shape, containing a double groove 01 and an inner hole cone angle α°. The inner hole is designed as a ball screw nut or roller screw nut with a circulating structure. The specific structure is as follows: Figure 4 and 5 As shown.

[0061] The ultra-precision machining equipment consists of the following components: 1. Left centering seat; 2. Workpiece (inner ring of integrated ball screw bearing); 3. Oilstone; 4. Locking screw; 5. Spacer; 6. Right centering seat; 7. Angular contact ball bearing; and 8. Support shaft. The overall structure is as follows: Figure 6 As shown. The right centering device consists of locking screw 4, spacer 5, right centering seat 6, angular contact ball bearing 7, and support shaft 8. The specific structure is as follows. Figure 11 As shown.

[0062] Installation details:

[0063] The spacer 5 is first installed into the inner hole of the right centering seat 6. The large inner hole surface 11 of the right centering seat is installed on the outer diameter of the angular contact ball bearing 7 by interference fit, ensuring that the outer ring end face of the angular contact ball bearing 7 is in close contact with the inner end face 10 of the right centering seat, and there is no gap at the rear end face after installation.

[0064] When centering workpiece 2, the centering angle γ conical surface of the right centering seat 6 contacts the centering angle α conical surface of workpiece 2, pressing against workpiece 2 and rotating synchronously with workpiece 2 to ensure machining accuracy, as detailed below. Figure 6 and 11 As shown.

[0065] An angular contact ball bearing 7 is mounted on a support shaft 8. The inner bore of the angular contact ball bearing 7 is fitted into the small outer diameter 08 of the support shaft via an interference fit. The bearing end face is in tight contact with the support shaft bearing positioning end face 09 of the support shaft 8, without any clearance. This design allows the right centering seat 6 to rotate synchronously with the workpiece 2 and withstand axial thrust, specifically as follows: Figure 6 and 11 As shown.

[0066] The locking screw 4 is inserted into the inner hole of the spacer 5 and screwed into the MC threaded hole of the support shaft 8, so that the end face of the large inner hole of the spacer 5 abuts against the end face of the inner ring of the angular contact ball bearing 7, ensuring no clearance. Specifically, as follows... Figure 6 and 11 As shown.

[0067] 2. Principle of ultra-precision inner ring groove of integrated ball screw bearing:

[0068] (1) Improved positioning accuracy:

[0069] Traditional positioning methods involve the end face of workpiece 2 contacting the end face of the positioning seat. However, this invention changes this by having the centering angle β conical surface of the left centering seat 1 contact the centering angle α conical surface of workpiece 2, significantly improving positioning accuracy. Specifically, as follows... Figure 9 and 10 As shown.

[0070] (2) Improvement of the clamping method:

[0071] The end face clamping method of workpiece 2 has been changed from the traditional clamping by two clamping rollers to the contact between the centering angle γ conical surface of the right centering seat 6 and the centering angle α conical surface of workpiece 2, clamping workpiece 2 and rotating synchronously with it. This improvement avoids the problem of large runout of the clamping rollers after clamping when workpiece 2 is relatively high, and at the same time prevents deep marks on the end face of workpiece 2 caused by wear of the clamping rollers, which would affect product accuracy. Specifically, as follows... Figure 11 and 14 As shown.

[0072] (3) Optimization of internal support structure:

[0073] The internal support structure has been changed from the traditional fixed type to the rotating type of the right centering seat 6, so that the workpiece 2 and the right centering seat 6 rotate synchronously, eliminating the relative movement between the contact surface of the workpiece 2 and the surface of the internal support, and avoiding problems such as scratches, black marks and scratches caused by friction.

[0074] (4) Innovation in processing technology:

[0075] The ultra-precision grooving process employs a two-station, two-step machining method. After the grooving is completed at one station, the process moves to the next station for further grooving. Simultaneously, both roughing and finishing oilstones (3) are used for machining, specifically as follows: Figure 7 and 8 As shown.

[0076] (5) Adjusting the initial tilt angle of the head:

[0077] Based on the required contact angle of workpiece 2, the initial tilt angle of the oscillating head can be adjusted to different angles such as 25°, 30°, and 40° to meet different processing requirements.

[0078] 3. Ultra-precision machining process of the inner ring groove of the integrated ball screw bearing for humanoid robots:

[0079] (1) Installation of left centering seat 1:

[0080] First, install the left centering seat centering shaft 03 of the left centering seat 1 into the corresponding positioning hole of the ultra-precision equipment, and tighten it with the screw through the locking screw hole MA of the left centering seat 1, so that the left centering seat positioning end face 04 of the left centering seat 1 is close to the positioning hole end face of the equipment.

[0081] (2) Installation of the right centering device:

[0082] Next, the support shaft centering round shaft 06 of the support shaft 8 of the right centering device is installed in the corresponding positioning hole of the ultra-precision equipment, ensuring that the support shaft positioning groove 07 of the support shaft 8 is aligned with the direction of the pin on the equipment. The support shaft 8 is then tightened with the screw through the locking screw hole MB, so that the support shaft positioning end face 05 of the support shaft 8 is close to the end face of the positioning hole of the equipment.

[0083] (3) Measurement of radial runout of the conical surface:

[0084] Measure the radial runout of the conical surfaces of the left centering seat 1 and the right centering seat 6 to ensure that the radial runout is controlled within the range of less than 0.002mm, so as to guarantee machining accuracy.

[0085] (4) Equipment adjustment and startup:

[0086] Adjust the equipment to ensure that the accuracy and appearance quality of workpiece 2 meet the requirements of the drawing, and ensure that all equipment functions are normal. Then, switch the equipment to automatic mode to prepare for processing.

[0087] (5) Positioning and clamping of workpiece 2:

[0088] The robotic arm pushes workpiece 2 into the ultra-precision machining area. The transmission mechanism on the right side of the equipment drives the right-side centering device to move, causing the centering angle γ conical surface of the right centering seat 6 to contact the centering angle α conical surface of workpiece 2. This pushes workpiece 2 so that the centering angle α conical surface on its other side contacts and clamps against the centering angle β conical surface of the left centering seat 1, ensuring no axial clearance. The speed of the transmission mechanism on the right side of the equipment can also be adjusted as needed for manual loading and unloading operations.

[0089] (6) Ultra-precision machining of the groove:

[0090] The rotating mechanism (head spindle) of the equipment drives the left centering seat 1, causing the workpiece 2 to rotate. The ultra-precision swivel head automatically feeds to the ultra-precision position for ultra-precision machining of the groove. After machining is completed, the ultra-precision swivel head retracts, and the right-side transmission mechanism of the equipment drives the right-side centering device back to its original position. The robot arm retracts and unloads the workpiece, repeating step (5) to proceed to the ultra-precision machining of the next workpiece 2. This cycle continues, as detailed below. Figure 7 As shown.

[0091] (7) Double-sided groove processing:

[0092] After the superfinishing of one side of the groove of workpiece 2 is completed, it enters another superfinishing station to perform superfinishing on the other side of the groove of workpiece 2 according to the above method, specifically as follows: Figure 8 As shown.

[0093] Example 2:

[0094] This embodiment is an improvement on embodiment 1. The difference is that embodiment 1 is applied to 3MZ3110 and 3MZ315D equipment, with bearing precision grade P4: outer diameter 34mm, groove diameter 29.59mm, and width 121mm.

[0095] Example 3:

[0096] This embodiment is an improvement on embodiment 1. The difference is that embodiment 1 is applied to 3MZ3110 and 3MZ315D equipment, with bearing precision grade P4: outer diameter 46.8mm, groove diameter 41.79mm, and width 158mm.

[0097] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An integrated ultra-precision machining equipment for the inner ring groove of a lead screw bearing, characterized in that, It comprises a left centering seat (1) for clamping a workpiece (2) and a right centering seat (6) connected to a supporting shaft (8) through an angular contact ball bearing (7), the outer diameter of the angular contact ball bearing (7) is in interference fit with the large inner hole surface (11) of the right centering seat, and the outer ring end surface of the angular contact ball bearing (7) is in close contact with the inner end surface (10) of the right centering seat, so that the workpiece (2) and the right centering seat (6) can rotate synchronously.

2. The integrated ball screw bearing inner raceway superfinishing apparatus of claim 1, wherein, The angular contact ball bearing (7) is installed on the supporting shaft (8), the inner hole of the angular contact ball bearing (7) is in interference fit with the small outer diameter (08) of the supporting shaft, and the bearing end surface is in close contact with the bearing positioning end surface (09) of the supporting shaft, without gap.

3. The integrated ball screw bearing inner raceway superfinishing apparatus of claim 2, wherein, The large inner hole surface (11) of the right centering seat is provided with a spacer (5) on the inner side.

4. The integrated ball screw bearing inner raceway superfinishing apparatus of claim 3, wherein, Locking screws (4) are installed in the inner hole of the spacer (5) and screwed into the MC screw hole of the supporting shaft (8), so that the large inner hole end surface of the spacer (5) is pressed against the inner ring end surface of the angular contact ball bearing (7), ensuring no gap.

5. The integrated ball screw bearing inner raceway superfinishing apparatus of claim 4, wherein, The centering angle α conical surface at one end of the workpiece (2) is in contact with the centering angle β conical surface of the left centering seat (1).

6. The integrated ball screw bearing inner raceway superfinishing apparatus of claim 5, wherein, The centering angle α conical surface at the other end of the workpiece (2) is in contact with the centering angle γ conical surface of the right centering seat (6).

7. The integrated ball screw bearing inner raceway superfinishing apparatus of claim 6, wherein, According to the contact angle required by the workpiece (2), the initial inclined angle of the swing head can be adjusted to 25°, 30° or 40°.

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