A fixture for flatness processing and a production method

Abstract

The present application relates to the technical field of machining fixture, in particular to a fixture for flatness machining and a production method, which is suitable for the machining of high-precision plane parts such as three-coordinate measuring instrument air floating guide rail, precision machine tool guide rail, marble platform, etc. The existing high-precision plane machining fixture generally has defects such as large clamping deformation, low positioning accuracy, poor universality, etc. The traditional top pressing method is easy to cause elastic deformation and springback of the workpiece, and the magnetic type fixture is limited by the magnetic conductivity of the material. The present application adopts an innovative structure of multi-point uniform pneumatic support combined with side linkage pressing, realizes the side clamping of the workpiece by driving the transmission rod with the support bolt to drive the pressing plate, forms uniform floating support by the bottom matrix type pneumatic support cylinder, effectively resists cutting vibration, fundamentally eliminates clamping deformation, greatly improves the machining accuracy and clamping efficiency, and is suitable for various materials and different specifications of workpieces.

Description

Technical Field

[0001] This invention belongs to the field of machining fixture technology, and particularly relates to a fixture for flatness machining and its production method. Background Technology

[0002] As a core device for precision geometric measurement, the measurement accuracy of a coordinate measuring machine (CMM) directly depends on the flatness accuracy of the air bearing guide rail. Therefore, CMMs have high requirements for the flatness of the air bearing guide rail.

[0003] In existing technologies, the following technical defects are commonly found in the flatness machining of high-precision guideways:

[0004] 1. Traditional pressure plate clamps directly clamp the workpiece from above with bolts. This can easily cause elastic bending deformation of the workpiece due to concentrated clamping force. After processing, the deformation rebounds, making it impossible to guarantee the final flatness accuracy.

[0005] 2. Existing fixtures cannot guarantee the parallelism between the workpiece reference surface and the machine tool table, requiring repeated adjustments using dial gauges, which is time-consuming; moreover, the bottom of the workpiece lacks uniform support, and vibrations are easily generated by cutting forces during processing, further reducing surface quality.

[0006] Therefore, there is an urgent need to develop a special fixture and supporting production method that can effectively eliminate clamping deformation, has high positioning accuracy, strong versatility, and is applicable to the flatness machining of various materials. Summary of the Invention

[0007] The present invention aims to control the parallelism deviation of the machined surface of a part after machining, and adopts the following technical solution: a fixture for flatness machining, including an L-shaped mounting base, wherein a mounting plate is bolted to the upper surface of the horizontal section of the L-shaped mounting base, and at least two sets of first support block groups and at least two sets of second support block groups are arranged parallel to each other along the length direction on the mounting plate. Each set of first support block groups includes two symmetrically arranged first support blocks, and each set of second support block groups includes two symmetrically arranged second support blocks.

[0008] A guide block is provided between the two first support blocks in each group of the first support blocks. A strip-shaped groove is formed along the length of the middle of the guide block. A positioning block is slidably disposed inside the strip-shaped groove. The two sides of the positioning block are fixedly connected to the opposite sides of the two first support blocks by bolts. A support bolt is threadedly connected to the side of the positioning block facing the opening of the strip-shaped groove. The end of the support bolt away from the positioning block penetrates the sidewall of the strip-shaped groove and extends outward. A locking nut is threadedly connected to the side of the support bolt that extends out of the strip-shaped groove. A positioning groove is formed at the end of the strip-shaped groove near the support bolt. A positioning nut of the same specification as the support bolt is engaged in the positioning groove. The shape of the positioning nut is adapted to the positioning groove, and it cannot be rotated after being inserted. The support bolt and the positioning nut are threadedly connected.

[0009] A guide rod is movably connected between the two second support blocks in each group of the second support blocks. The guide rod is hinged to the second support block via a pin, and one end of the guide rod is movably connected to the end of the guide block away from the strip groove via a pin. The guide rod has a bending angle, the vertex of which coincides with the hinge point of the guide rod and the second support block, and the bending angle is 120°-150°. A clamping head is bolted to the end of the guide rod away from the guide block. A clamping plate is fixedly connected to the side of the clamping head facing the vertical section of the L-shaped mounting base. A reinforcing rib is provided between the clamping head and the clamping plate, and the two ends of the reinforcing rib are welded and fixed to the clamping head and the clamping plate, respectively.

[0010] Multiple sets of pneumatic support cylinders are fixedly connected to the bottom of the horizontal section of the L-shaped mounting base. The support heads of the pneumatic support cylinders extend upwards through the horizontal section of the L-shaped mounting base and the mounting plate. The multiple sets of pneumatic support cylinders are arranged in a matrix and are used to form multi-point uniform support at the bottom of the workpiece. The vertical section of the L-shaped mounting base is a vertical plate. The front surface of the vertical plate is a reference positioning surface. Multiple sets of parallel strip-shaped adjustment grooves and bolt holes are formed on the vertical plate along the height and length directions. The strip-shaped adjustment grooves are used to adjust the clamping position of the clamping plate.

[0011] When the support bolt is screwed in, it pushes the guide block to slide away from the positioning block along the strip groove. The guide block drives the transmission rod to rotate around its hinge point with the second support block, causing the pressure plate at the other end of the transmission rod to rotate towards the vertical plate until the pressure plate is parallel to the vertical plate and presses the workpiece onto the reference positioning surface of the vertical plate. At this time, tightening the lock nut will complete the side positioning and clamping of the workpiece.

[0012] The pneumatic support cylinder is a self-locking type, with a support head extension stroke of 5mm-20mm and a rated support force of not less than 500N for a single cylinder. All pneumatic support cylinders are controlled by the same air circuit to ensure that the support head extends synchronously and makes uniform contact with the bottom reference surface of the workpiece, forming a stable floating support.

[0013] The reference positioning surface of the vertical plate is precision ground, with a surface roughness Ra of no more than 0.2 μm. A protective pad is attached to the surface of the clamping plate that contacts the workpiece to prevent scratches on the workpiece surface during clamping.

[0014] A sliding gap of 0.01mm-0.02mm is provided between the two sides of the guide block and the opposite sides of the first support block, and the sliding stroke of the guide block is 10mm-30mm. The upper surface of the positioning block is flush with the upper surface of the guide block, and both are 2mm-3mm lower than the upper surface of the mounting plate to avoid interference with the bottom of the workpiece.

[0015] The mounting plate has through holes that are compatible with the support head of the pneumatic support cylinder. The diameter of the through holes is 1mm-2mm larger than the diameter of the support head.

[0016] Beneficial effects of the present invention

[0017] Minimal clamping deformation and high machining accuracy: Abandoning the traditional top clamping method, a structure of side linkage clamping + bottom multi-point pneumatic support is adopted, which fundamentally avoids the elastic deformation of the workpiece caused by clamping force; the matrix arrangement of self-locking pneumatic support cylinders can evenly bear the weight of the workpiece, effectively resist the vibration caused by cutting force, and ultimately improve the flatness machining accuracy of the workpiece.

[0018] Significantly improved clamping efficiency: A group of clamping plates can be synchronously clamped by rotating a single support bolt, eliminating the need to adjust the position of each clamping plate individually, reducing clamping time by more than 60% compared to traditional fixtures; the strip adjustment groove on the upright plate can quickly adjust the position of the clamping plates to accommodate workpieces of different lengths and heights.

[0019] Extremely versatile: suitable for high-precision flat surface processing of various materials such as aluminum alloy, stainless steel, marble, and granite, and is not limited by magnetic conductivity; by increasing or decreasing the number of support block groups and pneumatic support cylinders, it can be adapted to workpieces of different sizes and specifications.

[0020] Stable and reliable structure: The transmission rod adopts a lever-type bending angle design, which can amplify the clamping force, and the clamping force is stable and adjustable; the positioning nut adopts a snap-fit ​​anti-rotation structure to ensure the adjustment accuracy of the support bolt; the pneumatic support cylinder has a self-locking function, and can still maintain the support force after the air is cut off, ensuring processing safety. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0022] Figure 2 This is a cross-sectional view of the overall structure of an embodiment of the present invention;

[0023] Figure 3 This is a cross-sectional schematic diagram of the transmission rod structure according to an embodiment of the present invention. Detailed Implementation

[0024] Example 1

[0025] like Figures 1-3 As shown, a flatness machining fixture includes an L-shaped mounting base 1, which is integrally welded from steel plates and subjected to stress-relief annealing treatment after welding to eliminate welding internal stress.

[0026] The upper surface of the horizontal section of the L-shaped mounting base 1 is connected to the mounting plate 2 by bolts. The mounting plate is made of steel plate, and the upper and lower surfaces are precision milled to ensure sufficient flatness accuracy.

[0027] Multiple sets of first support block groups and second support block groups are arranged parallel to each other along the length of the mounting plate 2. Each set of first support block groups includes two symmetrically arranged first support blocks 3, and each set of second support block groups includes two symmetrically arranged second support blocks 8. Both the first support blocks 3 and the second support blocks 8 are made of heat-treated steel and are fixed to the mounting plate 2 with bolts.

[0028] A guide block 4 is provided between the two first support blocks 3 in each first support block group. A strip groove 5 is provided in the middle of the guide block 4 along the length direction. A positioning block 6 is slidably provided inside the strip groove 5. The two sides of the positioning block 6 are fixedly connected to the opposite sides of the two first support blocks 3 by bolts.

[0029] A support bolt 7 is threadedly connected to the side of the positioning block 6 facing the opening of the slot 5. The end of the support bolt 7 away from the positioning block 6 passes through the side wall of the slot 5 and extends outward. A lock nut 15 is threadedly connected to the side of the support bolt 7 that extends out of the slot 5. A positioning groove 16 is provided in the slot 5 near the end of the support bolt 7. A positioning nut 17 of the same specification as the support bolt is engaged in the positioning groove 16. The positioning nut 17 cannot be rotated after being inserted. The support bolt 7 is threadedly connected to the positioning nut 17.

[0030] A guide rod 9 is hinged between the two second support blocks 8 of each second support block group via a pin 18. The guide rod 9 is made of heat-treated steel and has a bend angle, the vertex of which coincides with the hinge point. One end of the guide rod 9 is movably connected to the end of the guide block 4 away from the strip groove 5 via a pin 18, and the other end is bolted to a clamping head 11. A clamping plate 12 is welded to the side of the clamping head 11 facing the vertical plate 14, and a triangular reinforcing rib 13 is welded between the clamping head 11 and the clamping plate 12 to improve the rigidity of the clamping plate. A polyurethane protective pad 19 is attached to the surface of the clamping plate 12 that contacts the workpiece.

[0031] Multiple self-locking pneumatic support cylinders 10 are fixedly connected to the bottom of the horizontal section of the L-shaped mounting base 1. The pneumatic support cylinders 10 are evenly arranged in a matrix. The support head of the pneumatic support cylinder 10 extends upward through the horizontal section of the L-shaped mounting base 1 and the mounting plate 2. The mounting plate 2 has through holes that are adapted to the support head.

[0032] The vertical section of the L-shaped mounting base 1 is the upright plate 14. The front surface of the upright plate 14 is the reference positioning surface, which is precision ground by a surface grinder to achieve extremely high flatness and surface roughness requirements. Multiple sets of strip-shaped adjustment grooves and bolt holes are provided on the upright plate 14 along the height and length directions for adjusting the position of the clamping plate 12 according to the workpiece size.

[0033] The above-mentioned method for producing a flatness machining fixture

[0034] Includes the following steps:

[0035] S1 parts processing

[0036] (1) L-shaped mounting base processing: steel plate welding is used to make blanks and stress relief annealing is performed; the surfaces of the horizontal and vertical sections are milled, and the reference positioning surface of the vertical section is ground by a high-precision surface grinder; the pneumatic support cylinder mounting holes and mounting plate connecting bolt holes are processed in the horizontal section, and the strip adjustment groove and bolt holes are processed in the vertical section.

[0037] (2) Mounting plate processing: steel plate is cut to make blanks, and the upper and lower surfaces are milled to ensure that the flatness meets the design requirements; through holes and bolt holes of the pneumatic support cylinder support head are processed.

[0038] (3) Structural component processing: steel is used to cut and manufacture the first support block, second support block, guide block, positioning block, transmission rod, clamping head and clamping plate blanks, and heat treatment is carried out; each mating surface and connecting hole is milled, and the hinge hole of the transmission rod is machined by reaming to ensure the coaxiality of the hole; the surface of the clamping plate in contact with the workpiece is polished.

[0039] (4) Procurement of standard parts: Procurement of support bolts, lock nuts, positioning nuts, pins, self-locking pneumatic support cylinders and polyurethane protective pads that conform to national standards.

[0040] S2 Fixture Assembly

[0041] (1) Fix the pneumatic support cylinder 10 to the bottom of the horizontal section of the L-shaped mounting base 1 with bolts, ensure that the support head is coaxial with the through hole on the mounting plate 2, connect the pneumatic pipeline and perform an airtightness test.

[0042] (2) Fix the mounting plate 2 to the upper surface of the horizontal section of the L-shaped mounting base 1 with bolts, and use a dial indicator to adjust the perpendicularity between the upper surface of the mounting plate 2 and the reference positioning surface of the vertical plate 14 to ensure that the perpendicularity meets the design requirements.

[0043] (3) Fix the first support block 3 and the second support block 8 to the corresponding positions of the mounting plate 2 with bolts to ensure that the two support blocks in the same group are arranged symmetrically.

[0044] (4) Insert the positioning block 6 into the strip groove 5 of the guide block 4, and fix the positioning block 6 to the first support block 3 on both sides with bolts; pass the support bolt 7 through the side wall of the strip groove 5, the positioning nut 17 and the positioning block 6 in sequence, and screw in the locking nut 15.

[0045] (5) The transmission rod 9 is hinged between the second support blocks 8 by means of the pin 18, and one end of the transmission rod 9 is connected to the end of the guide block 4 by means of the pin 18; the clamping head 11 is fixed to the other end of the transmission rod 9 by bolts, and the clamping plate 12 and the reinforcing rib 13 are welded; the polyurethane protective pad 19 is pasted on the surface of the clamping plate 12.

[0046] S3 Fixture Adjustment

[0047] (1) Ventilate to make the support heads of all pneumatic support cylinders 10 extend to the maximum stroke synchronously. Use a dial indicator to check the height difference of the upper surface of each support head to ensure that the height difference is within the allowable range.

[0048] (2) Screw in the support bolt 7, observe the rotation of the transmission rod 9 and the pressing action of the pressure plate 12, adjust the initial position of the support bolt 7 so that the pressure plate 12 is parallel to the reference positioning surface of the upright plate 14 in the pressing state.

[0049] (3) Place standard test blocks for clamping tests, use feeler gauges to check the fit between the reference surface of the test block and the reference positioning surface of the upright plate 14, use an electronic level to check the flatness of the upper surface of the test block, and verify the clamping accuracy of the fixture.

[0050] 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 flatness machining, characterized in that, The device includes an L-shaped mounting base, a mounting plate bolted to the upper surface of the horizontal section of the L-shaped mounting base, at least one set of first support blocks on the mounting plate, guide blocks between the first support blocks, a strip groove on the guide block, a positioning block inside the strip groove, the positioning block being fixedly connected to the first support blocks on both sides, a support bolt being movably connected to one side of the positioning block, and the side of the support bolt away from the positioning block passing through one side of the strip groove; The mounting plate is provided with at least one set of second support blocks, and a transmission rod is provided between the second support blocks. The transmission rod is movably connected between the second support blocks, and one end of the transmission rod is movably connected to the end of the guide block away from the strip groove.

2. The fixture for flatness machining according to claim 1, characterized in that, The bottom of the L-shaped mounting base is fixedly connected to multiple sets of pneumatic support cylinders, and the support head of the pneumatic support cylinder passes through the L-shaped mounting base and the mounting plate; The guide rod is provided with a bending angle, which is located at the hinge point between the guide rod and the second support block. A clamping head is bolted to the side of the guide rod away from the strip groove. A clamping plate is provided on one side of the clamping head. A reinforcing rib is provided on the clamping head and the reinforcing rib is connected to the clamping plate.

3. The fixture for flatness machining according to claim 2, characterized in that, The vertical section of the L-shaped mounting base is a vertical plate, which is provided with multiple sets of strip-shaped adjustment grooves and bolt holes. The clamping plate is pushed and rotated by the transmission rod to form a clamp parallel to the vertical plate.

4. The fixture for flatness machining according to claim 1, characterized in that, A locking nut is provided on the side of the support bolt that protrudes from the strip groove. A positioning groove is provided in the strip groove near the end of the support bolt. A positioning nut of the same specification is provided in the positioning groove. The positioning nut cannot be rotated after being inserted.

5. The fixture for flatness machining according to claim 1, characterized in that, The pneumatic support cylinder is a self-locking pneumatic support cylinder. Multiple sets of pneumatic support cylinders are arranged in a matrix and are uniformly distributed. All pneumatic support cylinders are controlled by the same air circuit.

6. The fixture for flatness machining according to claim 2, characterized in that, The side of the upright plate facing the clamping plate is the reference positioning surface; a protective pad is attached to the surface of the clamping plate that contacts the workpiece.

7. The fixture for flatness machining according to claim 2, characterized in that, A sliding gap is provided between the guide block and the first support block.

8. A method for producing a flatness machining fixture as described in any one of claims 1-5, characterized in that, Includes the following steps: S1 Component Machining: Machining L-shaped mounting base, mounting plate, first support block, second support block, guide block, positioning block, transmission rod, clamping head and clamping plate respectively, and purchasing standard parts; S2 Fixture Assembly: Install the pneumatic support cylinder, mounting plate, first support block, second support block, guide block, positioning block, support bolt, transmission rod, clamping head and clamping plate in sequence; S3 Fixture Adjustment: Adjust the synchronization of the pneumatic support cylinder and the height difference of the support head, adjust the rotation angle of the transmission rod and the parallelism of the clamping plate, and perform clamping accuracy test.

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