Clamp, turning machine tool and machining method of clamp

Abstract

The invention provides a clamp, a turning airport and a machining method of the clamp. The clamp comprises a clamp body, a positioning ball, an elastic gasket and any clamp chuck, a conical hole is formed in one side of the clamp body to form a female opening, and a conical shaft is arranged on one side of the clamp chuck to form a male opening; the elastic gasket is arranged on the seam allowance, and a plurality of positioning beads are embedded in the elastic gasket; any clamp chuck is installed on the clamp body, so that the mother opening is matched with the sub-opening, the positioning beads are in contact with the mother opening and the sub-opening at the same time, and the multiple positioning beads can slide and / or roll in the elastic gasket and are pressed to deform so that the axis of the clamp body can coincide with the axis of the clamp chuck; a clamping part is arranged on the side, away from the seam allowance, of the clamp chuck. Repeated alignment of the zero point of the clamp and the machining benchmark is avoided, so that the switching efficiency of the part or the clamp is improved.

Description

Technical Field

[0001] The invention relates to the technical field of precision parts turning processing, and in particular to a fixture, a turning machine tool and a processing method of the fixture. Background Art

[0002] With the rapid and high-precision development of aerospace, automobile and other fields, the assembly accuracy requirements of parts are getting higher and higher, and the demand for precision / high-precision / ultra-high-precision parts is increasing. Therefore, higher requirements are also put forward for the processing size accuracy and production efficiency of parts. In the cutting of high-precision parts, the determination of the reference surface has a great influence on the processing accuracy of the parts. The clamping, positioning and determination of the processing reference of the parts account for a large proportion of the total processing time, which seriously affects the production efficiency. Therefore, high-precision clamping, rapid reference positioning, and rapid installation and switching of machining fixtures have become an important demand.

[0003] like Figure 1 As shown, the existing part turning clamping method includes spindle power output, fixture installation, part clamping, etc. The machine tool outputs its rotational power by rotating the spindle 9. A connecting flange 6 is installed at the end of the spindle 9, which increases the area of ​​the fixture installation end face on the one hand, and provides a connection interface for the installation of the fixture, such as a locking mechanism, a mounting hole, a mounting groove, etc. on the other hand. The turning fixture 7', such as a three-jaw fixture, an internal support fixture, etc., has a mounting plane on one side connected to the flange, and the other side includes a clamping mechanism for clamping the workpiece 10, such as a chuck of a three-jaw fixture, a bushing of an internal support fixture, and corresponding clamping tools, fixtures, etc., which apply radial force to clamp the part to be processed.

[0004] The connection between the spindle 9, the connecting flange 6, and the turning fixture 7' is generally made of countersunk bolts or special bolts. After the bolts are tightened, they rotate axially at the same speed as the spindle. Among them, the same machine tool can be matched with connecting flanges of different sizes to adapt to different turning fixtures, so the flange and the spindle are connected by bolts; the same connecting flange can be matched with different turning fixtures, so it is also more convenient to use bolts to connect the turning fixture and the flange.

[0005] The turning process of the workpiece 10 needs to ensure the reference of two dimensions: the parallelism of the end face and the coaxiality of the axial direction. Among them, the two geometric tolerances of end face parallelism and coaxiality will be transferred to each other: the tolerance zone of end face parallelism (also known as the total runout of the end face) is the maximum distance between two parallel planes perpendicular to the reference axis and with a distance equal to the tolerance value; the coaxiality tolerance is the allowable variation of the actual measured axis relative to the reference axis (also known as the circular runout. The reference axis is generally the spindle center axis during turning clamping). According to the above clamping method, it is necessary to ensure that the end face of the spindle 9, the two end faces of the connecting flange, and the end face of the turning fixture 7' have very high flatness, are parallel to each other, and have very high coaxiality with the rotation center axis of the spindle 9.

[0006] To ensure the above precision requirements, the general operation is as follows: (i) When the machine tool leaves the factory, the spindle end face and the connecting flange end face will be processed by turning, grinding, etc. to ensure flatness and coaxiality, and will be connected by countersunk bolts as the basic reference of the machine tool. However, if the connecting flange is replaced, the bolt connection will not have high matching accuracy (generally 10 -1 mm, much lower than the processing of precision parts 10 -2 (ii) Turning fixtures such as three-jaw fixtures are customized fixtures with good end face flatness. When used, they have good end face parallelism after being connected to the connecting flange. If only different workpieces are replaced for processing or the processing procedures of the workpieces are changed, the operation is relatively simple. However, after replacing the turning fixture, the clamping jaws and clamping fixtures of the fixture still need to be re-aligned and processed. In the above process, the methods for coaxiality alignment and turning correction of the spindle-connecting flange and the connecting flange-turning fixture are as follows: Taking the connection of the connecting flange-turning fixture as an example, first use the countersunk bolt to pre-tighten the turning fixture to the connecting flange, start the machine tool to rotate the spindle, and measure the runout of a certain reference diameter of the outermost end face on the roundness table to obtain its coaxiality data. If the requirements are not met, loosen the pre-tightened countersunk bolt and fine-tune the radial position of the fixture, tighten the countersunk bolt again and re-measure its circular runout, and repeat this process until the coaxiality requirements are met. If the requirements cannot be met after multiple adjustments or are close to the coaxiality requirements, tighten the countersunk bolt, start the spindle and use a turning tool to perform turning correction on the outer end of the fixture chuck, thereby ensuring that the fixture chuck and the spindle have the same coaxiality and end face parallelism.

[0007] When switching between different processes or when processing different parts in the same process, it is necessary to re-determine the processing datum and zero point, which may cause cumulative errors. In order to ensure the coaxiality of the connecting flange, turning fixture, workpiece and spindle, the installation datum needs to be recalibrated and turned after replacing the connecting flange and turning fixture. This process is also called datum alignment. In the field of precision machining, since the parts have more complex machining shapes and precision requirements, conventional general fixtures such as three-jaw chucks cannot meet the requirements, and special fixtures are generally used. Summary of the invention

[0008] The object of the present invention is to provide a fixture, a turning machine and a processing method of the fixture, so as to avoid repeated alignment of the zero point of the fixture and the processing reference, so as to improve the switching efficiency of parts or fixtures.

[0009] The technical solution of the present invention is: a clamp, including a clamp body, a positioning bead, an elastic gasket and any clamp chuck, one side of the clamp body is provided with a conical hole to form a female port, one side of the clamp chuck is provided with a conical shaft to form a sub-port; the sub-port is provided with the elastic gasket, and a plurality of positioning beads are embedded in the elastic gasket; any of the clamp chucks is installed on the clamp body so that the female port and the sub-port are adapted, the positioning bead is in contact with the female port and the sub-port at the same time, and the plurality of positioning beads can slide and / or roll in the elastic gasket respectively and deform under pressure so that the axis line of the clamp body and the axis line of the clamp chuck coincide; a clamping portion is provided on the side of the clamp chuck away from the sub-port. Sliding refers to the axial displacement of the positioning bead along the clamp chuck, rolling refers to the self-rotation of the positioning bead, and compressive deformation refers to the outer shape forming a sphere similar to an ellipse.

[0010] Preferably, the positioning beads are evenly distributed along the circumference of the mother port and the child port, and a plurality of the positioning beads are evenly distributed in the axial direction of the clamp body.

[0011] Preferably, the elastic gasket is adhered to the surface of the sub-port by using acetone.

[0012] Preferably, the elastic gasket is made of plastic.

[0013] Preferably, the elastic modulus of the positioning bead is lower than the elastic modulus of the clamp body and the clamp chuck.

[0014] Preferably, a flange is provided on the clamp chuck, a plurality of countersunk through holes are circumferentially provided on the flange, a plurality of screw holes are circumferentially provided on the clamp body, the plurality of screw holes correspond one-to-one to the plurality of countersunk through holes, the flange is fitted with the end face of the clamp body, and a first screw is installed at the countersunk through hole and the screw hole.

[0015] Preferably, the clamping portion is a clamping hole or a clamping shaft.

[0016] The present invention also provides a turning machine tool, comprising a spindle, a connecting flange connected to the spindle and the above-mentioned clamp, wherein the clamp body in the clamp is fixed to the connecting flange by a second screw, and the axis of the clamp coincides with the axis of the spindle.

[0017] The present invention also provides a method for processing a fixture, which is used to process the above-mentioned fixture, comprising: Step 1: Processing the fixture body, respectively making the end face of one side of the fixture body match the flatness of the connecting flange on the turning machine, making the circumferential runout of the tapered hole on the fixture body match the circumferential runout of the machine tool spindle, and making the coaxiality of the tapered hole on the fixture body match the spindle of the machine tool; Step 2: Processing the fixture chuck so that the circumferential runout of the tapered shaft on one side of the fixture chuck matches the circumferential runout of the tapered hole of the fixture body; processing the clamping part on the other side of the fixture chuck so that the clamping part meets the requirements for workpiece clamping; Step 3, applying an organic solvent on one surface of the elastic gasket, and pasting the elastic gasket on the sub-mouth of the clamp chuck, with the side of the elastic gasket coated with the organic solvent attached to the sub-mouth; Step 4: Install the positioning beads on the elastic gasket; Step 5: Close the female and male openings to complete the processing of the fixture.

[0018] Preferably, the circumferential runout of the tapered hole and the tapered shaft is greater than 10 -2 mm, and the surface roughness is Ra0.05μm.

[0019] Compared with the related art, the present invention has the following beneficial effects: First, the present invention designs the fixture as a split structure including a fixture body and a fixture chuck. The fixture body can be installed with a fixture chuck of any structure. Once the fixture body is fixed to the connecting flange on the machine tool, it is only necessary to replace the fixture chuck adapted to the workpiece due to the processing requirements of different workpieces in the later stage without disassembling the fixture body, thereby avoiding repeated alignment of the zero point of the fixture and the processing reference, so as to improve the switching efficiency of the workpiece or fixture. Second, the present invention designs the fixture chuck and the fixture body to be conical and centered, and sets a positioning bead that can be deformed on the conical surface to ensure the coaxiality between the fixture chuck and the fixture body when the fixture chuck is quickly replaced, and can effectively ensure and achieve the circumferential runout of the rotary type parts higher than 10 -2 mm high-precision and ultra-high-precision machining to obtain high-quality parts; 3. The fixture body can be installed with any structure of fixture chuck, and the fixture chuck and workpiece can be replaced with high precision in a short time without re-alignment and repositioning, thereby reducing production line downtime, improving production efficiency, and making the production process more continuous and efficient; Fourth, the present invention designs the fixture as a split structure including a fixture body and a fixture chuck. The fixture body can be installed with a fixture chuck of any structure, which can realize the standardization of the fixture body. Only different types of fixture chucks need to be processed, which can meet different processing requirements while saving a lot of manufacturing costs of the fixture. 5. A positioning bead is set between the sub-mouth of the fixture chuck and the female mouth of the fixture body to achieve point contact, which can avoid the influence of stains and sticky debris on the female mouth on the assembly accuracy, and also avoid the wear caused by surface-to-surface contact, so as to achieve adaptive centering of the fixture chuck installed on the fixture body and maintain high precision; 6. The present invention designs the clamp chuck and the clamp body to be centered on the conical surface, and arranges deformable positioning beads on the conical surface, which can repeat high-precision positioning and reduce dependence on manual labor. Only manual cleaning of the sub-mouth and the main mouth surface and tightening of the first screw are required, which greatly reduces the burden on operators and reduces the possibility of human error. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the existing turning clamping; Figure 2 A schematic diagram of the structure of the clamp provided by the present invention; Figure 3 A cross-sectional view of the clamp provided by the present invention; Figure 4 for Figure 3 The enlarged schematic diagram of point C in FIG. Figure 5 A partial schematic diagram of a turning machine provided by the present invention.

[0021] In the accompanying drawings: 1. clamp body; 11. female mouth; 12. screw hole; 13. mounting surface; 2. positioning bead; 3. elastic gasket; 31. ball hole; 4. clamp chuck; 41. female mouth; 42. clamping part; 43. flange; 44. countersunk through hole; 5. first screw; 6. connecting flange; 7. clamp; 8. second screw; 9. spindle; 10. workpiece. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0023] like Figure 2 , Figure 3 As shown, a clamp 7 provided in this embodiment includes a clamp body 1, a positioning bead 2, an elastic gasket 3 and any clamp chuck 4.

[0024] A conical hole is provided on one side of the clamp body 1 to form a female port 11, and a plurality of screw holes 12 are circumferentially provided on the outer end surface of the female port 11. A finely machined mounting surface 13 is formed on the other side of the clamp body 1.

[0025] A conical shaft is provided on one side of the clamp chuck 4 to form a sub-mouth 41, and a clamping portion 42 for clamping a workpiece is provided on the other side of the clamp chuck 4. A flange 43 is provided on the clamp chuck 4, and the flange 43 is arranged close to the sub-mouth 41. A plurality of countersunk through holes 44 are circumferentially provided on the flange 43. The plurality of screw holes 12 correspond to the plurality of countersunk through holes 44 one by one, and the flange 43 is fitted with the end surface of the clamp body 1, and a first screw 5 is installed at the countersunk through hole 44 and the screw hole 12.

[0026] like Figure 4 As shown, the elastic gasket 3 is arranged on the surface of the sub-mouth 41, and a plurality of ball holes 31 are arranged in the circumferential and axial directions in the elastic gasket 3 (uniformly distributed along the circumference of the mother mouth 11 and the sub-mouth 41, and a plurality of uniformly distributed in the axial direction of the clamp body 1). One positioning bead 2 is installed in each of the ball holes 31. Any of the clamp chucks 4 is installed on the clamp body 1 so that the mother mouth 11 and the sub-mouth 41 are conically adapted, and the positioning bead 2 is in contact with the mother mouth 11 and the sub-mouth 41 at the same time. The plurality of positioning beads 2 can slide and / or roll in the elastic gasket 3 respectively and deform under pressure so that the axis center line of the clamp body 1 and the axis center line of the clamp chuck 4 coincide.

[0027] The elastic gasket 3 is made of plastic material, such as thermoplastic polyurethane elastomer TPE, and has good elasticity. The clamp body 1 and the clamp chuck 4 are made of tool steel, such as Cr12MoV, 40Cr, T8, etc. The positioning ball 2 is a solid steel ball, whose elastic modulus is slightly lower than that of the clamp body 1 and the clamp chuck 4 (150~200Gpa), and has very good wear resistance, such as cast steel, ductile cast iron, stainless steel, etc.

[0028] When the clamp chuck 4 and the clamp body 1 are fixedly connected by the first screw 5, an axial force is generated between the two, causing the sub-mouth 41 and the female mouth 11 to slide. At this time, the elastic gasket 3 provides better elastic support, and the positioning bead 2 makes point contact with the sub-mouth 41 and the female mouth 11. During the installation of the clamp chuck 4 and the clamp body 1, if the axes of the two do not overlap but there is still a certain extrusion pressure, the positioning bead 2 with a slightly lower elastic modulus will produce a slight deformation to achieve self-adjustment in a very small range, thereby prompting the axis of the clamp chuck 4 to quickly and adaptively align with the axis of the clamp body 1.

[0029] The installation of the clamp chuck 4 and the clamp body 1 uses the elastic gasket 3 on the conical surface and the positioning bead 2 for achieving point contact as the intermediate support, which can not only ensure the uniform axial force during the tightening process of the first screw 5, but also avoid the loss of positioning accuracy caused by stains and wear on the contact surface.

[0030] The clamping chuck 4 can be customized according to the characteristics of the clamped part of the workpiece 10 to be processed. For example, the clamping portion 42 can be designed as a clamping hole or a clamping shaft. If it is a clamping hole, the fixed part of the workpiece 10 is clamped in an external holding manner and combined with other positioning tooling (such as Figure 5 As shown); if it is a clamping shaft, the fixed part of the workpiece 10 is clamped in an internal support manner and combined with other positioning tooling.

[0031] like Figure 5 As shown, the present invention further provides a turning machine tool, comprising a spindle 9, a connecting flange 6 connected to the spindle 9 and the above-mentioned fixture 7, wherein the mounting surface 13 of the fixture body 1 in the fixture 7 is in contact with the connecting flange 6 and fixed by a second screw 8, and the axis of the fixture 7 coincides with the axis of the spindle 9. The workpiece 10 is clamped on the clamping portion 42.

[0032] The present invention also provides a method for processing a fixture, which is used to process the above-mentioned fixture, comprising the following steps: Step 1: Process the fixture body 1, finish the end face of one side of the fixture body 1 to form the mounting face 13, and also process the end face A of one side of the fixture body 1. The size requirements of the mounting face 13 and the end face A on the other side meet the flatness requirements of the connection flange 6 on the turning machine. Finish the conical hole on the other side of the fixture body 1 so that the circumferential runout value of the conical hole meets the circumferential runout requirements of the machine tool spindle 9, and the conical hole meets the coaxiality requirements of the machine tool spindle 9. And the surface roughness of the conical hole meets the requirements of matching the conical hole on the fixture chuck 4.

[0033] Step 2: Process the fixture chuck 4, and finish the tapered shaft on one side of the fixture chuck 4, so that the circumferential runout value of the tapered shaft meets the requirements for adapting to the tapered hole of the fixture body 1, and the surface roughness of the tapered shaft meets the requirements for adapting to the tapered hole of the fixture body 1. Finish the clamping part 42 on the other side of the fixture chuck 4, so that the clamping part 42 meets the requirements for workpiece clamping. The flange 43 of the finish-machined fixture chuck 4 is used to be assembled on the end surface B on the fixture body 1.

[0034] The circumferential runout value of a tapered hole and a tapered shaft is 10 -3 mm, and the surface roughness is Ra0.05 μm. In this embodiment, the mounting surface 13, the end surface A and the end surface B are turned and ground to a coaxiality and plane dimension accuracy of 0.003 mm, and a surface roughness of Ra0.03 μm.

[0035] Step 3: Apply an organic solvent (such as acetone) on one side of the elastic gasket 3 . Adhere the elastic gasket 3 to the sub-opening 41 of the clamp chuck 4 by a solvent method, and the side of the elastic gasket 3 coated with the organic solvent is attached to the sub-opening 41 .

[0036] Step 4: install the positioning beads 2 on the elastic gasket 3.

[0037] Step 5, fix the clamp body 1 and the clamp chuck 4 by tightening the first screw 5, and loosen and tighten the first screw 5 after the solvent evaporates, so as to complete the bonding of the elastic gasket 3 and the positioning bead 2. The elastic gasket 3 and the positioning bead 2 can be installed on other clamp chucks 4 according to steps 3 and 4.

[0038] Step six, disassemble the fixture chuck 4 for use.

[0039] By using the fixture of the present invention, it is verified through the test of processing annular parts, the processed parts are removed and another workpiece to be processed is installed. The total installation time is less than 1 minute and no coaxial alignment or processing is required. The workpiece and the clamping part of the inner support can also be installed offline, and then installed with the fixture body installed on the connecting flange. The installation of the clamp chuck and the workpiece does not need to occupy the machine tool time, and the processing switch of different parts can be completed within 20 seconds. In addition, the fixture joint and the workpiece as a whole can be quickly switched between machine tools equipped with the same interface of this solution. Compared with the use of conventional connection interfaces for fixture installation and part clamping, the clamping time is reduced by more than 90%, and the efficiency is greatly improved; in addition, the parts processed by this interface and the corresponding fixture can achieve high-precision turning, the dimensional accuracy of the circular runout (roundness) can reach 0.006mm, and the processing quality stability is better.

[0040] The fixture body using the quick clamping interface included in the present invention can also be installed with an external-embracing type quick-change special fixture, a three-jaw chuck type quick-change special fixture, a five-jaw quick-change special fixture, and other methods with the same installation method.

[0041] By adopting the clamp of the present invention, rapid end face assembly and axial assembly between parts can be realized with high precision and high efficiency, and thus can be used for assembly connection between parts and components with high dimensional requirements.

[0042] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A clamp, characterized in that: The invention comprises a clamp body (1), a positioning bead (2), an elastic gasket (3) and any clamp chuck (4); one side of the clamp body (1) is provided with a conical hole to form a female opening (11), and one side of the clamp chuck (4) is provided with a conical shaft to form a sub-opening (41); the sub-opening (41) is provided with the elastic gasket (3), and a plurality of positioning beads (2) are embedded in the elastic gasket (3); any clamp chuck (4) is installed on the clamp body (1) so that the female opening (11) and the sub-opening (41) are adapted to each other, the positioning bead (2) is in contact with the female opening (11) and the sub-opening (41) at the same time, and the plurality of positioning beads (2) can slide and / or roll in the elastic gasket (3) respectively and deform under pressure so that the axis center line of the clamp body (1) and the axis center line of the clamp chuck (4) coincide with each other; the side of the clamp chuck (4) away from the sub-opening (41) is provided with a clamping portion (42).

2. The clamp according to claim 1, characterized in that: The positioning beads (2) are evenly distributed along the circumference of the female opening (11) and the female opening (41), and a plurality of the positioning beads (2) are evenly distributed in the axial direction of the clamp body (1).

3. The clamp according to claim 1, characterized in that: The elastic gasket (3) is adhered to the surface of the sub-port (41) using acetone.

4. The clamp according to claim 1, characterized in that: The elastic gasket (3) is made of plastic.

5. The clamp according to claim 1, characterized in that: The elastic modulus of the positioning bead (2) is lower than the elastic modulus of the clamp body (1) and the clamp chuck (4).

6. The clamp according to claim 1, characterized in that: The clamp chuck (4) is provided with a flange (43), and a plurality of countersunk through holes (44) are circumferentially provided on the flange (43). The clamp body (1) is provided with a plurality of screw holes (12) in a circumferential manner, and the plurality of screw holes (12) correspond one-to-one to the plurality of countersunk through holes (44). The flange (43) is fitted with an end surface of the clamp body (1), and a first screw (5) is installed at the countersunk through hole (44) and the screw hole (12).

7. The clamp according to claim 1, characterized in that: The clamping portion (42) is a clamping hole or a clamping shaft.

8. A turning machine tool, comprising a spindle (9) and a connecting flange (6) connected to the spindle (9), characterized in that: It also comprises a clamp (7) as claimed in any one of claims 1 to 7, wherein the clamp body (1) in the clamp (7) is fixed to the connecting flange (6) by a second screw (8), and the axis centerline of the clamp (7) coincides with the axis centerline of the main shaft (9).

9. A method for processing a fixture, used for processing the fixture as claimed in any one of claims 1 to 7, characterized in that: include: Step 1, machining the fixture body (1), respectively making the end face of one side of the fixture body (1) match the flatness of the connecting flange on the turning machine, making the circumferential run-out of the conical hole on the fixture body (1) match the circumferential run-out of the main shaft of the machine tool, and making the coaxiality of the conical hole on the fixture body (1) match the main shaft of the machine tool; Step 2: machining the fixture chuck (4) so ​​that the circumferential run-out of the tapered shaft on one side of the fixture chuck (4) matches the circumferential run-out of the tapered hole of the fixture body (1); machining the clamping portion (42) on the other side of the fixture chuck (4) so ​​that the clamping portion (42) meets the requirements for clamping the workpiece; Step three, applying an organic solvent on one side of the elastic gasket (3), and pasting the elastic gasket (3) on the sub-mouth (41) of the clamping head (4), so that the side of the elastic gasket (3) coated with the organic solvent is attached to the sub-mouth (41); Step 4: Install the positioning bead (2) on the elastic gasket (3); Step 5: close the female opening (11) and the female opening (41); and complete the processing of the fixture.

10. The method for processing a fixture according to claim 9, characterized in that: The circumferential runout of the tapered hole and the tapered shaft is higher than 10 -2 mm, and the surface roughness is Ra0.05μm.

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