Aerodynamic bearing machining clamp

Abstract

The application discloses a kind of clamps for aerodynamic bearing processing, it is related to precision machining clamp technical field.The clamp includes base, one side of base top is equipped with clamping mechanism, the other side is equipped with positioning block, the bottom of base is equipped with pneumatic support cylinder, its output end extends to the interval region of clamping mechanism and positioning block through base, and the side of positioning block is equipped with lateral antiskid mechanism.Slidable slider is equipped in clamping mechanism, fixed groove is equipped in the opposite side of slider and positioning block, fixed strip and avoidance groove are equipped in groove, and fixed strip is matched with workpiece sealing air groove.The workpiece is positioned by fixed strip clamping, and the surface to be processed is pre-arched as arc by cooperation of pneumatic support cylinder pushing, and the wave shape, stepped micro error generated by cutting vibration can be offset after workpiece springback.

Description

Technical Field

[0001] This invention belongs to the field of precision machining fixture technology, and particularly relates to a special fixture for machining the air film gap of pneumatic bearings in a coordinate measuring machine. Background Technology

[0002] Pneumatic bearings are key components for achieving frictionless, high-precision motion in coordinate measuring machines (CMMs), relying on an extremely thin air film to suspend the moving parts. Among these components, the air film gap is the most critical parameter, with its thickness typically controlled between 1 and 10 micrometers. Its machining accuracy directly determines the bearing performance and the overall measurement accuracy of the machine.

[0003] During the machining of irregularly shaped air film gaps, the cutting force of the machine tool will cause the workpiece to undergo its own elastic deformation, resulting in continuous up-and-down vibration.

[0004] The amplitude of this vibration is exactly on the same order of magnitude as the machining accuracy requirement of the air film gap, which causes the actual cutting depth of the tool to fluctuate randomly. The working surface of the machined bearing will have waviness and small-sized pits, affecting the accuracy.

[0005] At the same time, since the machining surface is an inclined surface, if it is machined directly according to ordinary machining methods and materials, the machining surface will have a wavy undulation, which will affect the accuracy of the bearing surface.

[0006] Therefore, developing a technical solution to suppress the elastic up-and-down vibration of workpieces has become a key problem to be solved in the production of pneumatic bearings for coordinate measuring machines. Summary of the Invention

[0007] This invention aims to achieve low-error machining of the inclined surface of the air film gap at the top of the air bearing, and adopts the following technical solution:

[0008] A pneumatic bearing processing fixture, characterized in that: it includes a workpiece and a base, a clamping mechanism is detachably and fixedly connected to one side of the top of the base, a positioning block is detachably and fixedly connected to the side of the base away from the clamping mechanism, a pneumatic support cylinder is detachably and fixedly connected to the bottom of the base, the output end of the pneumatic support cylinder passes through the base until the output end is set between the clamping mechanism and the positioning block, and a lateral anti-slip mechanism is detachably and fixedly connected to one side of the positioning block;

[0009] The clamping mechanism includes a slider. Both the slider and the positioning block are provided with opposing fixing grooves and stop blocks on one side. The fixing groove is provided with a fixing strip and a clearance groove. The fixing strip is matched with the sealing grooves provided on both sides of the workpiece.

[0010] The clamping mechanism includes an upper guide seat and a lower guide seat, which are detachably and fixedly connected. Both the upper and lower guide seats are provided with a receiving cavity, and a slider is provided in the receiving cavity. Guide blocks are provided at the top and bottom of the slider. A guide rail is provided on the inner wall of the receiving cavity, and the guide rail and guide blocks are used in conjunction.

[0011] A compression bolt and a threaded hole are provided between the upper guide seat and the lower guide seat, and one end of the compression bolt is movably connected to the slider.

[0012] The lateral anti-slip mechanism is fixedly connected to the base on the side away from the stop block. The lateral anti-slip mechanism includes a support base, the bottom of which is provided with multiple sets of countersunk holes, and the side wall of the support base is provided with multiple sets of fastening structures.

[0013] Furthermore, a rubber buffer pad is provided at the top of the output end of the pneumatic support cylinder.

[0014] Furthermore, the groove width is 0.02~0.05 mm larger than the workpiece sealing groove width.

[0015] Furthermore, the clearance between the slide rails of the upper and lower guide seats and the slider guide block is 0.01~0.03 mm.

[0016] Furthermore, the fastening bolt of the lateral anti-slip mechanism is provided with a nylon head at its front end, and the nylon head contacts the side of the workpiece.

[0017] The pneumatic bearing workpiece to be processed is placed between the clamping mechanism and the positioning block, so that the sealing grooves on both sides of the workpiece correspond to the fixing bars in the slider and the positioning block's fixing groove, respectively, and the end of the workpiece is in contact with the stop block, completing the initial positioning of the workpiece. Rotating the compression bolt pushes the slider along the slide rail towards the positioning block, causing the fixing bars on both sides to embed into the sealing grooves of the workpiece, achieving horizontal limitation of the workpiece; the clearance groove at the top of the fixing bar provides deformation allowance for the workpiece, allowing the middle part of the workpiece to produce an upward elastic bend without rigid constraint under clamping conditions. Then, the pneumatic support cylinder is activated, its output end pushing upwards to the middle area of ​​the bottom of the workpiece, causing the surface to be processed on the workpiece to arch upwards, forming a uniform and controllable micro-convex arc surface.

[0018] During machining, the cutting tool cuts the arc-shaped surface to be machined along a planar trajectory; the pneumatic support cylinder maintains a constant output force, continuously offsetting part of the cutting impact force and suppressing the vertical vibration of the workpiece; the fixing bars on both sides always maintain the lateral positioning of the workpiece, preventing the workpiece from shifting or rotating. After machining, the pressure is first released to release the pushing force of the pneumatic support cylinder, and the workpiece relies on its own elastic rebound to reset, and the surface to be machined returns from an arc shape to a plane. This rebound process can offset the wavy or stepped micro-errors caused by elastic tool deflection and micro-vibration during the cutting process, ultimately obtaining a more flat air film gap working surface.

[0019] Beneficial effects

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] It can eliminate microscopic surface shape errors. Through controllable pre-arching elastic deformation and post-processing springback compensation, it offsets the wavy and stepped machining errors caused by workpiece elastic vibration and tool deflection during the cutting process, improves the flatness and thickness uniformity of the air film gap working surface, and ensures the machining accuracy of pneumatic bearings.

[0022] Clamping and deformation compatible design. The fixing bar works in conjunction with the workpiece sealing groove to achieve precise positioning, and the avoidance groove provides space for deformation. While ensuring the reliability of clamping and positioning, it does not hinder the controllable pre-bending deformation of the workpiece and avoids the clamping stress interfering with the pre-deformation effect.

[0023] Improve machining stability. The bottom pneumatic support cylinder provides controllable upward support force, which is used to create a pre-arc machining surface and absorb some of the vibration energy during the cutting process, further reducing the elastic vibration amplitude of the workpiece and reducing the generation of ripples on the machined surface.

[0024] It balances machining accuracy and efficiency. Vibration can be suppressed and surface errors eliminated without reducing cutting parameters, improving machining efficiency and reducing production costs while ensuring machining quality. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0026] Figure 2 This is a cross-sectional view of the overall structure with the workpiece in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the exploded structure of the clamping mechanism according to an embodiment of the present invention;

[0028] Figure 4 This is a partial cross-sectional enlarged schematic diagram of an embodiment of the present invention.

[0029] In the diagram: 1. Base; 2. Clamping mechanism; 21. Upper guide seat; 22. Lower guide seat; 23. Cavity; 24. Slider; 25. Guide block; 26. Slide rail; 27. Extrusion bolt; 28. Fixing groove; 29. ​​Stop block; 3. Positioning block; 4. Pneumatic support cylinder; 5. Lateral anti-slip mechanism; 51. Support seat; 52. Countersunk hole; 53. Fastening bolt; 6. Workpiece. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Comparative Example

[0032] When clamped, the bottom surface of the workpiece is completely in contact with the planar support surface of the fixture, and the sides of the workpiece are pressed and fixed by rigid clamping blocks. The workpiece is constrained to the initial planar state, with no deformation allowance in the vertical direction and the middle area.

[0033] During the cutting process, the tool continuously acts on the thin-walled working surface of the workpiece. Under the alternating cutting force, the workpiece generates its own elastic up-and-down vibration, accompanied by local elastic tool deflection. Since the bottom of the workpiece is supported by a rigid plane and the sides are rigidly clamped, the displacement generated by the vibration cannot be compensated by controllable deformation. The actual cutting depth of the tool fluctuates irregularly with the vibration of the workpiece.

[0034] After machining is completed and the clamp is released, the workpiece elastically rebounds and resets. The micro-morphology of the machined working surface shows a wavy pattern corresponding to the cutting vibration frequency, and there are step-like micro-errors on the tool path. The flatness of the working surface and the uniformity of the air film gap thickness do not meet the design accuracy requirements.

[0035] Example 1

[0036] like Figure 1-4 As shown, this embodiment of the invention provides a fixture for processing pneumatic bearings, including a workpiece 6 and a base 1. A clamping mechanism 2 is connected to one side of the top of the base 1 via hexagonal socket head cap screws, and a positioning block 3 is connected to the side of the base 1 away from the clamping mechanism 2 via hexagonal socket head cap screws. Two pneumatic support cylinders 4 are bolted to the bottom of the base 1. The output end of the pneumatic support cylinder 4 passes through a through hole in the base 1 until the output end is positioned between the clamping mechanism 2 and the positioning block 3. A rubber buffer pad is adhered to the top of the output end of the pneumatic support cylinder 4.

[0037] The clamping mechanism 2 includes a slider 24. The slider 24 and the positioning block 3 are provided with opposing fixing grooves 28 and stop blocks 29 on one side. The fixing groove 29 is provided with fixing strips and clearance grooves. The fixing strips are matched with the sealing grooves provided on both sides of the workpiece.

[0038] The clamping mechanism 2 includes an upper guide seat 21 and a lower guide seat 22, which are connected by bolts. Both the upper guide seat 21 and the lower guide seat 22 have rectangular cavities 23, and sliders 24 are disposed within these cavities. Guide blocks 25 are integrally formed at the top and bottom of the slider 24. A slide rail 26, which mates with the guide blocks 25, is provided on the inner wall of the cavity 23. The clearance between the slide rail 26 and the guide blocks 25 is 0.02 mm.

[0039] Threaded holes are provided on the side walls of the upper guide seat 21 and the lower guide seat 22. A clamping bolt 27 is installed in the threaded hole. The inner end of the clamping bolt 27 is movably connected to the slider 24 through a ball joint.

[0040] The lateral anti-slip mechanism 5 is bolted to the side of the base 1 away from the stop block 29 of the clamping mechanism 2. The lateral anti-slip mechanism 5 includes an L-shaped support base 51, with two sets of countersunk holes 52 at the bottom for connection with the base 1. Two sets of fastening bolts 53 are provided on the vertical sidewall of the support base 51, with nylon heads bonded to the front ends of the fastening bolts 53, and the nylon heads contact the side of the workpiece 6.

[0041] How to use this embodiment:

[0042] 1. Fix the fixture onto the worktable of the ultra-precision milling machine via base 1, and adjust the position of the fixture to align it with the machine tool coordinate system.

[0043] 2. Place the pneumatic bearing workpiece 6 to be processed between the clamping mechanism 2 and the positioning block 3, so that the rear end face of the workpiece 6 is in contact with the stop block 29, and at the same time, align the air sealing grooves on both sides of the workpiece 6 with the fixing strips in the slider 24 and the fixing groove 28 of the positioning block 3 respectively.

[0044] 3. Rotate the compression bolt 27 to push the slider 24 to move towards the positioning block 3, so that the fixing strip is embedded in the sealing grooves on both sides of the workpiece 6, completing the initial positioning and lateral clamping of the workpiece; the clearance groove reserves space for upward deformation in the middle of the workpiece, without restricting the elastic arching of the workpiece.

[0045] 4. Start the pneumatic support cylinder 4, adjust the support pressure, so that the rubber buffer pad is in close contact with the middle area of ​​the bottom of the workpiece 6 and continuously pushes upward, so that the surface to be processed of the workpiece 6 arches upward, forming a uniform and controllable micro-convex arc surface, and maintaining stable support pressure.

[0046] 5. Tighten the two fastening bolts 53 of the lateral anti-slip mechanism 5 so that the nylon mandrel presses against the side of the workpiece 6 to prevent the workpiece from rotating during processing.

[0047] 6. Perform cutting machining on the working surface of the air film gap according to the set cutting parameters.

[0048] 7. After processing, first loosen the fastening bolts 53 of the lateral anti-slip mechanism, then release the pressure of the pneumatic support cylinder 4, remove the bottom thrust, and the workpiece 6 returns to its original position by its own elastic rebound, thus offsetting the wavy and stepped micro-errors generated during the cutting process; finally, rotate the extrusion bolt 27 in the opposite direction to loosen the slider 24 and take out the processed workpiece.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fixture for machining pneumatic bearings, characterized in that: The device includes a workpiece and a base. A clamping mechanism is detachably and fixedly connected to one side of the top of the base. A positioning block is detachably and fixedly connected to the side of the base away from the clamping mechanism. A pneumatic support cylinder is detachably and fixedly connected to the bottom of the base. The output end of the pneumatic support cylinder passes through the base until the output end is located between the clamping mechanism and the positioning block. A lateral anti-slip mechanism is detachably and fixedly connected to one side of the positioning block. The clamping mechanism includes a slider. Both the slider and the positioning block are provided with opposing fixing grooves and stop blocks on one side. The fixing groove is provided with a fixing strip and a clearance groove. The fixing strip is matched with the sealing grooves provided on both sides of the workpiece.

2. The fixture for machining pneumatic bearings according to claim 1, characterized in that: The clamping mechanism includes an upper guide seat and a lower guide seat, which are detachably and fixedly connected. Both the upper and lower guide seats are provided with a receiving cavity, and a slider is provided in the receiving cavity. Guide blocks are provided at the top and bottom of the slider. A guide rail is provided on the inner wall of the receiving cavity, and the guide rail and guide blocks are used in conjunction.

3. The fixture for machining pneumatic bearings according to claim 2, characterized in that: A compression bolt and a threaded hole are provided between the upper guide seat and the lower guide seat, and one end of the compression bolt is movably connected to the slider.

4. The fixture for machining pneumatic bearings according to claim 1, characterized in that: The lateral anti-slip mechanism includes a support base, the bottom of which is provided with multiple sets of mounting holes, and the sidewall of the support base is provided with multiple sets of fasteners.

5. The fixture for machining pneumatic bearings according to claim 1, characterized in that: A buffer pad is provided at the top of the output end of the pneumatic support cylinder.

6. The fixture for machining pneumatic bearings according to claim 4, characterized in that: The fastener has a non-metallic top head at its front end.

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