A turning fixture and process for thin-walled ring-shaped parts

Abstract

This invention provides a turning fixture and process for thin-walled ring-shaped parts, including a three-jaw chuck. The three-jaw chuck comprises a jaw body and three jaws evenly spaced circumferentially on the top of the jaw body. Each jaw has an arc-shaped stop fixedly mounted on its top, parallel to the top of the jaw body. The three arc-shaped stops do not contact each other and have the same curvature. The top surface of each arc-shaped stop has multiple radially inward steps, which are wider in the middle and narrower at both ends, and are evenly distributed in the axial direction. The clamping force of the fixture mainly comes from the resistance generated by the cutting tool on the part. A smaller initial clamping force can be used to clamp the three-jaw chuck, greatly reducing radial deformation and axial warping during the initial clamping process of the part. This further improves the machining accuracy of the part and solves the technical problem in the prior art where the flatness and parallelism requirements of the upper and lower end faces of deformed parts cannot be guaranteed after turning.

Description

Technical Field

[0001] This invention belongs to the field of parts processing and relates to a fixture, specifically a turning fixture and process for thin-walled ring-shaped parts. Background Technology

[0002] Thin-walled parts have a large ratio of radial dimension to wall thickness, often reaching tens or even hundreds of times. The workpiece has weak rigidity and is prone to deformation during clamping, which brings great difficulties to the cutting process. If the machining process is not reasonable in the finishing stage, it is difficult to meet the requirements of the drawings.

[0003] There are many types of thin-walled parts, commonly including sleeves, rings, and discs. Each type of thin-walled part has its own characteristics. When machining them on a lathe, it is necessary to identify the weak points of each part based on its specific characteristics and to adopt different machining paths and clamping methods to ensure machining accuracy. Among them, rings and discs are particularly prone to warping and deformation due to their weak axial stiffness. Deformation of these weak points often affects the quality requirements of other parts. When machining the upper and lower end faces and inner and outer circles of such thin-walled parts, the industry usually adopts a roughing-then-finishing process. In order to ensure the machining efficiency of the parts, the roughing process generally uses a simple and efficient three-jaw chuck in conjunction with a regular three-jaw chuck for turning. Because the machining allowance in the roughing process is large and the cutting resistance is very high, a large clamping force is usually used to clamp the workpiece without sacrificing machining efficiency. During clamping, elastic deformation is inevitable. After roughing, the deformation is restored, and the part inevitably produces triangular deformation, which affects the subsequent finish machining process. Especially for some thin-walled ring parts with high requirements for the flatness and parallelism of the upper and lower end faces, continuing to use the traditional three-jaw or expansion sleeve machining process for finish machining will undoubtedly aggravate the deformation of the parts, so that the flatness and parallelism can never meet the drawing requirements and the machining stability is not guaranteed.

[0004] Currently, the industry's efforts to tackle high-precision machining of thin-walled ring parts mainly focus on solving workpiece clamping, reducing cutting heat, and eliminating residual stress. Much of the effort is spent on eliminating part deformation during the transition between roughing and finishing processes or reducing cutting parameters to decrease cutting resistance during machining. However, the industry has neglected how to effectively utilize the deformation characteristics between roughing and finishing processes and the cutting resistance during machining. This not only increases workload and reduces machining efficiency but also prevents further improvement in part quality. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a turning fixture and process for thin-walled ring-shaped parts, so as to solve the technical problems in the prior art that deformed parts cannot be stably clamped in the fine turning process and the flatness and parallelism of the upper and lower end faces of the parts cannot be guaranteed after fine turning.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] This invention provides a turning fixture for thin-walled ring-shaped parts, including a three-jaw chuck. The three-jaw chuck includes a jaw body and three jaws that are circumferentially spaced at equal intervals on the top of the jaw body. Each jaw has an arc-shaped stop fixedly disposed on its top, parallel to the top of the jaw body. The three arc-shaped stops do not contact each other and have the same curvature. The top surface of each arc-shaped stop has multiple radially inward steps, which are wider in the middle and narrower at both ends, and are of equal thickness in the axial direction.

[0008] The claw has multiple bolt holes at equal intervals, and the claw is fixedly mounted on the top surface of the claw disc body by means of bolt holes and screws.

[0009] The inner and outer walls of the arc-shaped stop directly above the chuck are provided with through holes that communicate with the bolt holes.

[0010] A reinforcing post is provided between the bottom of the claw and the arc-shaped blocks on both sides, and the two ends of the reinforcing post are welded to the bottom of the arc-shaped blocks and the side of the claw, respectively.

[0011] The top of the jaw located inside the three-jaw chuck has a protrusion.

[0012] The arc-shaped stop is welded onto the jaw.

[0013] A method for clamping thin-walled ring-shaped parts, using a turning fixture for such parts, specifically includes the following steps:

[0014] Step 1: Set the three-jaw chuck to the open position, place the self-propelled accessory on the radial front end of the three jaws, and lock the three-jaw chuck.

[0015] Step 2: Machine the upper surface of the step of the arc-shaped stop flat, and clean the junction between the upper surface and the inner wall of the arc-shaped stop.

[0016] Step 3: Loosen the three-jaw chuck, place the rough-machined part on the stepped surface of the arc-shaped stop, slowly and manually tighten the three-jaw chuck, and observe the contact between the arc-shaped stop and the part.

[0017] Step 4: Stop locking when the inner wall of the arc-shaped stop just touches the part, then rotate the part. Stop rotating the part when the highest point of the outer circle protrusion of the part reaches the left or right corner of the arc-shaped stop.

[0018] Step 5: Rotate the part in the opposite direction to bring the highest point of the protruding part on the outer circle of the part to the middle position of the arc-shaped stop. Manually lock the three-jaw chuck and rotate the part left and right. When the highest point of the protruding part of the part cannot be rotated to the sides in the middle position of the arc-shaped stop, use a torque wrench to initially lock the three-jaw chuck according to the specified torque.

[0019] Step 6: Check the clamping of the part again. After confirming that the part is not loose, perform precision machining on the upper surface and inner hole of the part.

[0020] Step 7: After one side of the part is machined, manually release the three-jaw chuck to remove the part, flip the part over, and repeat steps 3 to 6 to complete the turning of the part.

[0021] Compared with the prior art, the beneficial technical effects of this invention are:

[0022] (I) The clamping force of the fixture in this invention mainly comes from the resistance generated on the part by the cutting tool. Therefore, a smaller initial clamping force can be used to clamp the three-jaw chuck, which greatly reduces the radial deformation and axial warping of the part during the initial clamping process, so that the machining accuracy of the part can be further improved. This solves the technical problem in the prior art that the flatness and parallelism of the upper and lower end faces of the deformed part cannot be guaranteed after machining.

[0023] (II) Compared with traditional fixtures, when using this invention, the worker only needs to initially lock the three-jaw chuck according to the torque required by the process. By utilizing the triangular deformation characteristics of the part after rough turning, and controlling the contact between the inner wall of the step of the annular side stop and the part, the fixture can achieve self-clamping during the turning process, ensuring stable clamping of the part. This avoids the problem of excessively tight or loose clamping caused by different clamping techniques of different workers, and to a certain extent eliminates the dependence on the operator's skills. The clamping is simple, with a high success rate and good stability, solving the technical problem of the inability to stably clamp deformed parts in the finishing process in the prior art.

[0024] (III) During the cutting process, the clamping force of the part can be adjusted by adjusting the cutting amount and cutting feed, and the process parameters when the cutting force and clamping force are balanced can be found, so that the workpiece is kept in a stable processing environment, thus getting out of the predicament of repeatedly trying to find the optimal clamping force process parameters. Attached Figure Description

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

[0026] Figure 2 This is a schematic diagram of the installation of the workpiece to be machined according to the present invention;

[0027] Figure 3 This is a schematic diagram of the clamping of the arc-shaped stop and the part in this invention;

[0028] Figure 4 This is a schematic diagram of the arc-shaped stop block in this invention.

[0029] The meanings of the labels in the diagram are as follows: 1-Three-jaw chuck, 2-Arc-shaped stop, 3-Step, 4-Bolt hole, 5-Screw, 6-Through hole, 7-Reinforcing post, 8-Protrusion, 9-Automotive accessory, 10-Part;

[0030] 101-Claw disc body, 102-Claw.

[0031] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, all components in this invention are those known in the art.

[0033] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0034] This invention provides a turning fixture for thin-walled ring-shaped parts, including a three-jaw chuck 1. The three-jaw chuck 1 includes a jaw body 101 and three jaws 102 that are equally spaced along the circumference on the top of the jaw body 101. Each jaw 102 has an arc-shaped stop 2 that is parallel to the top of the jaw body 101 fixedly disposed on its top. The three arc-shaped stops 2 do not contact each other and have the same curvature. The top surface of the arc-shaped stops 2 has multiple radially inward steps 3. The steps 3 are wider in the middle and narrower at both ends, and the steps 3 are distributed with equal thickness in the axial direction.

[0035] See Figure 4 The term "step 3 is narrow at both ends and wide in the middle" refers to the upper surface of the step being narrow at both ends and wide in the middle.

[0036] In the above technical solution, when the part begins to be processed, the part and the fixture rotate counterclockwise around the axis. At this time, the cutting resistance of the tool on the part is exactly opposite to the rotation direction of the part. The cutting resistance forces the high point of the part to move towards both ends of the arc-shaped stop. The structural feature of the upper step of the arc-shaped stop, which is wide in the middle and narrow at both ends, further restricts the tendency of the high point of the part to move towards both ends of the arc-shaped stop. This makes the part clamped tighter and tighter under the action of the cutting force. Therefore, the clamping force of the fixture mainly comes from the resistance generated by the tool on the part during cutting. Thus, a smaller initial clamping force can be used to clamp the three-jaw chuck, which greatly reduces the radial deformation and axial warping of the part during the initial clamping process. This further improves the machining accuracy of the part and solves the technical problem in the prior art that the flatness and parallelism requirements of the upper and lower end faces of the part cannot be guaranteed after the deformed part is machined.

[0037] Furthermore, compared to traditional fixtures, when using this invention, the worker only needs to initially lock the three-jaw chuck according to the torque required by the process. Utilizing the triangular deformation characteristics of the part after rough turning, the fixture can achieve self-clamping during the turning process by controlling the contact between the inner wall of the step of the annular side stop and the part. This ensures stable clamping of the part and avoids excessively tight or loose clamping caused by different clamping techniques of different workers. To a certain extent, it eliminates the dependence on the operator's skills. The clamping is simple, with a high success rate and good stability, solving the technical problem in the prior art that deformed parts cannot be stably clamped in the finish turning process.

[0038] During the cutting process, the clamping force of the part can be adjusted by adjusting the cutting amount and cutting feed, and the process parameters when the cutting force and clamping force are balanced can be found, so that the workpiece is kept in a stable processing environment, thus getting out of the predicament of repeatedly trying to find the optimal clamping force process parameters.

[0039] Specifically, the claw 102 has multiple bolt holes 4 at equal intervals, and the claw 102 is fixedly mounted on the top surface of the claw plate body 101 through the bolt holes 4 and screws 5.

[0040] Specifically, the inner and outer walls of the arc-shaped stop 2 directly above the chuck 102 are provided with through holes 6 that communicate with the bolt holes 4, so as to facilitate the installation of the chuck 102 on the chuck body 101.

[0041] Specifically, a reinforcing post 7 is provided between the bottom of the jaw 102 and the arc-shaped blocks 2 on both sides. The two ends of the reinforcing post 7 are welded to the bottom of the arc-shaped blocks 2 and the side of the jaw 102, respectively, to enhance the stability of the three-jaw chuck of the arc-shaped blocks.

[0042] Specifically, a protrusion 8 is provided on the top of the jaw 102 located inside the three-jaw chuck 1 for clamping the auxiliary parts of the vehicle.

[0043] Specifically, the arc-shaped stop 2 is welded onto the chuck 102.

[0044] Furthermore, the present invention also provides a clamping method for thin-walled ring-shaped parts, using a turning fixture for thin-walled ring-shaped parts, specifically including the following steps:

[0045] Step 1: Set the three-jaw chuck 1 to the open state, place the self-propelled accessory 9 at the radial front end of the three jaws 102, and lock the three-jaw chuck 1.

[0046] Step 2: Flatten the upper surface of the step 3 of the arc-shaped stop 2, and clean the junction between the upper surface and the inner wall of the arc-shaped stop 2.

[0047] Step 3: Loosen the three-jaw chuck 1, place the rough-machined part 10 on the upper surface of the step 3 of the arc-shaped stop 2, slowly and manually lock the three-jaw chuck 1, and observe the contact between the arc-shaped stop 1 and the part 10.

[0048] Step 4: Stop locking when the inner wall of the arc-shaped stop 2 just contacts the part 10, then rotate the part 10. When the high point of the outer circle protrusion of the part 10 reaches the left or right corner of the arc-shaped stop 2, stop rotating the part 10.

[0049] Step 5: Rotate part 10 in the opposite direction to bring the highest point of the outer circle protrusion of part 10 to the middle position of the arc-shaped stop 2. Manually lock the three-jaw chuck 1 and rotate part 10 left and right. When the highest point of the protrusion of part 10 cannot be rotated to the sides in the middle position of the arc-shaped stop 2, use a torque wrench to initially lock the three-jaw chuck 1 according to the specified torque.

[0050] Since the gap between the inner wall of the arc-shaped stop and the outer circle of the part is the smallest at this point, the rotational resistance of the part will increase significantly at this point. When the resistance is the largest, the part stops rotating. At this time, the position of the part corresponding to the corner of the arc-shaped stop is the high point of the protruding part on the outer circle of the part.

[0051] Step 6: Check the clamping of part 10 again. After confirming that part 10 is not loose, perform precision machining on the upper end face and inner hole of part 10.

[0052] Step 7: After one side of part 10 is machined, manually release the three-jaw chuck 1 to remove part 10, flip part 10 over, and repeat steps 3 to 6 to complete the turning of part 10.

[0053] In the above technical solution, the part after rough machining is a part that undergoes triangular deformation, with three raised high points on it.

[0054] Working principle of a three-jaw chuck:

[0055] The opening and closing functions are accomplished by rotating the screw on the side of the chuck left and right. To open, rotate the screw on the chuck body to one side to open the three-jaw chuck. To lock, rotate the screw on the chuck body to the other side to lock the three-jaw chuck.

Claims

1. A turning fixture for thin-walled ring-like parts, comprising a three-jaw chuck (1), said three-jaw chuck (1) comprising a chuck body (101) and three jaws (102) equidistantly arranged in the circumferential direction on the top of the chuck body (101), characterized in that, The top of each said claw (102) is fixedly provided with an arc-shaped stopper (2) parallel to the top of the claw disc body (101), and the three said arc-shaped stoppers (2) are not in contact with each other and have the same curvature; the top surface of the said arc-shaped stopper (2) is provided with a plurality of radially inward steps (3), the said steps (3) are wide in the middle and narrow at both ends, and the said steps (3) are distributed with equal thickness in the axial direction; A plurality of bolt holes (4) are equidistantly arranged on the said claw (102), and the claw (102) is fixedly arranged on the top surface of the claw disc body (101) through the bolt holes (4) and screws (5); A through hole (6) in communication with the bolt hole (4) is arranged on the inner wall and the outer wall of the arc-shaped stopper (2) directly above the claw (102); A reinforcing column (7) is arranged between the claw (102) and the bottom of the arc-shaped stopper (2) on both sides of the claw (102), and the both ends of the reinforcing column (7) are respectively welded to the bottom of the arc-shaped stopper (2) and the side surface of the claw (102).

2. The turning jig for thin-wall ring-like parts according to claim 1, wherein A protrusion (8) is arranged on the top of the claw (102) inside the three-claw chuck (1).

3. The turning jig for thin-wall ring-like parts according to claim 1, wherein The arc-shaped stopper (2) is welded on the claw (102).

4. A method of clamping thin-walled ring-like parts, characterized in that, The turning clamp for the thin-walled ring-shaped part according to any one of claims 1 to 3 comprises the following steps: Step one, set the three-claw chuck (1) to an open state, place the self-turning auxiliary part (9) on the radial front end of the three claws (102), and lock the three-claw chuck (1); Step two, turn the upper surface of the step (3) of the arc-shaped stopper (2) flat, and perform a root cleaning process on the junction between the upper surface and the inner wall of the arc-shaped stopper (2); Step three, loosen the three-claw chuck (1), place the rough-turned part (10) on the upper surface of the step (3) of the arc-shaped stopper (2), slowly manually lock the three-claw chuck (1), and observe the contact condition of the arc-shaped stopper (1) and the part (10); Step four, stop locking when the inner wall of the arc-shaped stopper (2) just contacts the part (10), then rotate the part (10), and stop rotating the part (10) when the high point of the protruding part of the outer circle of the part (10) is turned to the left and right corners of the arc-shaped stopper (2); Step five, reversely rotate the part (10), turn the high point of the protruding part of the outer circle of the part (10) to the middle position of the arc-shaped stopper (2), further manually lock the three-claw chuck (1), and rotate the part (10) left and right, when the high point of the protruding part of the part (10) cannot be rotated to both sides in the middle position of the arc-shaped stopper (2), use a torque wrench to preliminarily lock the three-claw chuck (1) according to the specified torque; Step six, check the clamping condition of the part (10) again, and perform fine turning processing on the upper end surface and the inner hole of the part (10) after confirming that the part (10) is not loose; Step seven, after one side of the part (10) is processed, manually loosen the three-claw chuck (1) to remove the part (10), turn over the part (10), and repeat steps three to six, thereby completing the turning of the part (10).

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