An adaptive form-following centering fixture and automatic clamping method

Abstract

The present application belongs to the technical field of clamping, and provides a self-adaptive contour centering clamp and an automatic clamping method. The self-adaptive contour centering clamp comprises an end cover, an outer ring, a floating contour positioning cylinder, a driving clamping cylinder, an inner ring, a lifting ring, a rib plate and a PLC control system. The automatic clamping method can replace the traditional process ring clamping method, realize self-adaptive contour positioning and clamping of the cylinder workpiece, and eliminate the turning process ring process, thereby reducing material consumption. After the outer ring, the cylindrical roller bearing and the center axis of the lathe spindle are installed in the self-adaptive contour centering clamp, the middle cylinder segment can be guaranteed to coincide with the center axis of the lathe spindle. The contour positioning of the blank cylinder workpiece is realized through the floating contour positioning cylinder, and the cylinder workpiece is clamped through the driving clamping cylinder, so that the axis of the cylinder workpiece is guaranteed not to deviate and the stress is uniform. The present application is realized based on the PLC control system, the clamping force is quantitatively controlled by feedback regulation of an oil pressure gauge and a proportional valve, and clamping deformation is reduced.

Description

Technical Field

[0001] This invention belongs to the field of clamping technology and relates to an adaptive conformal centering fixture and an automatic clamping method. Background Technology

[0002] The aerospace industry has numerous thin-walled cylindrical shells with large length-to-diameter ratios. These shells are typically formed using spinning, resulting in significant roundness errors. To meet service performance requirements, several shells need to be welded together. For assembly, the outer diameter, inner diameter, and end faces of both ends of the shell must be machined using the central section's axis as a reference. However, welding introduces positional errors between different sections, compromising the coaxiality of the entire shell. The welded shell can reach 2-3 meters in length. When machining the ends, to avoid interference, the four-jaw chuck at one end of the lathe needs to be removed. However, relying solely on a single chuck can lead to excessive overhang of the shell, causing axis misalignment and compromising accuracy. Therefore, after removing the chuck, clamping constraints must be applied to provide support while ensuring the central axis of the central section is concentric with the lathe spindle before and after chuck removal. Thus, achieving proper clamping and ensuring coaxiality becomes a critical problem to solve.

[0003] In traditional turning processes, process rings are often used to solve this problem. The process ring has a symmetrical stepped structure, with a large central ring and symmetrical smaller rings at both ends. Each small ring has 18 bolts evenly distributed around its circumference. The bolt extension is adjusted to accommodate the surface contour errors of different cylindrical workpieces. During turning, a process ring is first pre-fixed on each side of the central cylindrical section. The cylindrical workpiece is then mounted on the lathe, and the two ends are clamped using a four-jaw chuck. Next, the circular runout of the central cylindrical section is measured near ends A and B. By individually adjusting the position of the four-jaw chuck jaws, the axis of the central cylindrical section is aligned with the lathe spindle axis. Once the accuracy requirements are met, the outer diameters of ends A and B are machined to a smooth finish. Finally, to minimize the cutting allowance of the process ring, the circular runout of the process ring is measured again, and the extension of each bolt on the small ring is continuously adjusted to ensure the axis of the process ring coincides with the axis of the cylindrical workpiece. Because the roundness of the process ring cannot meet the coaxiality requirements, the large ring of the process ring needs to be machined to ensure accuracy. Finally, the inner circle and end face of the A-end cylinder section are machined. After machining the A-end cylinder section, the workpiece orientation of the cylinder is reversed, and the jaws of the four-jaw chuck are adjusted with the machined A-end cylinder section and the process ring as references to make the intermediate cylinder section concentric with the lathe spindle before machining the B-end cylinder section.

[0004] Traditional clamping methods rely on process rings to ensure the concentricity of the intermediate cylinder section's axis with the lathe spindle. Each time a cylinder workpiece is machined, the process ring bolts must be adjusted before the large ring of the process ring is machined. In mass production, the consumption of process rings is enormous, significantly increasing manufacturing costs and causing substantial waste. Furthermore, the time workers spend adjusting the process ring bolts can reach 30-40 minutes, greatly reducing machining efficiency. Therefore, there is an urgent need to develop an adaptive conformal centering fixture and an automated clamping method to replace process rings, saving costs while improving efficiency. Summary of the Invention

[0005] The problem to be solved is to overcome the shortcomings of existing process ring clamping and to provide an adaptive conformal centering fixture and an automatic clamping method.

[0006] The technical solution of this invention:

[0007] An adaptive conformal centering fixture includes an end cap 8, an outer ring 7, a floating conformal positioning cylinder 6, an active clamping cylinder 5, an inner ring 4, a lifting ring 14, a rib plate 15, and a PLC control system.

[0008] The floating conformal positioning cylinder 6 and the active clamping cylinder 5 are hydraulically driven. The floating conformal positioning cylinder 6 can achieve adaptive conformal positioning of the cylindrical workpiece 2, and the active clamping cylinder 5 applies an active clamping force to the cylindrical workpiece 2. The sequence of the floating conformal positioning cylinder 6 first conforms to the shape, and then the active clamping cylinder 5 actively clamps, achieves adaptive centering and clamping. The inner ring 4 is used to install the floating conformal positioning cylinder 6 and the active clamping cylinder 5. The cylindrical roller bearing 9 installed on the outer side of the inner ring 4 realizes the turning rotation of the cylindrical workpiece 2. At the same time, the cylindrical roller bearing 9 is installed... The position is concentric with the lathe spindle to ensure coaxiality requirements; the end cover 8 provides side sealing for the centering fixture; different oil passages are arranged inside the outer ring 7 to achieve sequential clamping; the lifting ring 14 is used for lifting and installation; the stiffening plate 15 is used to improve overall rigidity; a PLC control system is used to realize the sequential control and automatic clamping of the centering fixture, and the appropriate clamping force is quantitatively applied to cylindrical workpieces 2 with different wall thicknesses through the monitoring and adjustment of the oil pressure gauge and proportional valve; the adaptive conformal centering fixture can meet the adaptive conformal positioning and centering clamping functions of the cylindrical workpiece 2. The core technology of this invention is: replacing the "turning process ring centering" process with adaptive conformal centering, reducing processing costs and improving processing efficiency.

[0009] The outer ring 7 is a modular structure, divided into upper and lower parts. The upper part is a circular ring with mounting holes inside; the lower part is a rectangular base 704 for mating with the guide rail of the lathe 1. An oil inlet and an oil drain are provided at the connection between the upper ring and the lower rectangular base 704. The outer ring 7 includes an active clamping cylinder oil inlet 701, a floating conformal positioning cylinder oil inlet 702, an oil drain 703, a rectangular base 704, and an inner ring mounting hole 705. The outer ring 7 is mounted on the lathe 1 via a rectangular base 704, ensuring that the axis of the outer ring 7 is aligned with the axis of the spindle of the lathe 1. The inner circumferential surface of the outer ring 7 has an inner ring mounting hole 705, and its outer circumferential surface has an active clamping cylinder oil inlet hole 701, a floating conformal positioning cylinder oil inlet hole 702, an oil drain hole 703, and a lifting ring mounting hole 707. The outer surface of the outer ring 7 has an end cap fixing hole 706.

[0010] The inner ring 4 is a stepped ring in the shape of a ring, containing four stepped segments, namely the first stepped ring 403, the second stepped ring 408, the third stepped ring 407, and the fourth stepped ring 406. The second stepped ring 408, which has the largest diameter, has an active clamping cylinder oil passage 401 and a floating conformal positioning cylinder oil passage 402 that connect the active clamping cylinder oil inlet 701 and the floating conformal positioning cylinder oil inlet 702, respectively. The outer side of the widest third stepped ring 407 is used to install cylindrical roller bearings. 9. The third stepped ring 407 has 16 evenly distributed floating conformal positioning cylinder mounting holes 404 and active clamping cylinder mounting holes 405 for mounting the active clamping cylinder 5 and the floating conformal positioning cylinder 6; the first stepped ring 403 and the fourth stepped ring 406 with the smallest diameter are used to install the sealing ring 10; the inner ring 4 is installed inside the outer ring 7 and fixed by the end cover 8; the cylindrical roller bearing 9 is installed between the outer ring 7 and the inner ring 4, thereby ensuring the centering and rotation of the cylindrical workpiece 2 after clamping;

[0011] The floating conformal positioning cylinder 6 is a hydraulic auxiliary support cylinder driven by oil pressure. There are eight cylinders in total, which are evenly distributed in the mounting holes on the inner ring 4. When hydraulic oil is supplied to the floating conformal positioning cylinder 6 through the oil circuit 402 of the floating conformal positioning cylinder, the support rod extends. After the support rod contacts the workpiece 2 of the cylinder, it automatically clamps, but does not provide clamping force, thereby realizing the conformal positioning function.

[0012] The active clamping cylinder 5 is a hydraulically driven clamping cylinder, consisting of eight cylinders, which are evenly distributed in the mounting holes on the inner ring 4. When hydraulic oil is supplied to the active clamping cylinder 5 through the active clamping cylinder oil circuit 401, the support rod extends. By adjusting the hydraulic oil pressure, different clamping forces can be provided quantitatively, thereby realizing the clamping function.

[0013] The PLC control system enables automated sequential operation of the active clamping cylinder 5 and the floating conformal positioning cylinder 6. It is divided into an information control layer and a drive execution layer. The drive execution layer includes a hydraulic station, proportional valves, solenoid valves, an oil pressure gauge, and an adaptive conformal centering fixture. The drive execution layer is equipped with two sets of proportional valves and solenoid valves, used to control the hydraulic oil circuits of the active clamping cylinder 5 and the floating conformal positioning cylinder 6, respectively. The hydraulic station provides hydraulic oil; the proportional valves precisely adjust the pressure; the solenoid valves are on / off valves used to control the opening and closing of the oil circuit; and the oil pressure gauge detects the clamping force. The information control layer includes a host computer, a controller, connector unit-IO slave stations, and a touch screen. Communication uses an EtherCAT bus. The connector unit-IO slave stations are connected to the proportional valves, solenoid valves, and oil pressure gauge, respectively, and pressure monitoring is achieved using analog current. The PLC control system enables automated sequential clamping and release of this fixture.

[0014] Furthermore, the hydraulic oil is divided into two paths. One path of hydraulic oil passes through the inlet 702 of the floating conformal positioning cylinder, the oil passage 402 of the floating conformal positioning cylinder, and connects to eight floating conformal positioning cylinders 6. The other path of hydraulic oil passes through the inlet 701 of the active clamping cylinder, the oil passage 401 of the active clamping cylinder, and connects to eight active clamping cylinders 5. The two paths of hydraulic oil share a drain hole 703. The eight active clamping cylinders 5 and the eight floating conformal positioning cylinders 6 are connected in series in their respective oil passages to ensure synchronous movement and uniform force on the cylinder workpiece 2.

[0015] Furthermore, the active clamping cylinder 5 and the floating conformal positioning cylinder 6 are alternately distributed and evenly fixed in the mounting holes of the inner ring 4.

[0016] Furthermore, the hydraulic pressure gauge detects the hydraulic oil pressure and feeds it back to the proportional valve to apply a quantitative clamping force. The reading on the hydraulic pressure gauge can also accurately detect whether the fixture is in contact with the workpiece in the cylinder.

[0017] Furthermore, the fixture of this invention differs from the clamping method of the traditional process ring 13, which requires turning to ensure that the axis is consistent with the axis of the cylindrical workpiece 2. When installing the adaptive conformal centering fixture, it is only necessary to align the axis of the outer ring 7 and the cylindrical roller bearing 9 with the axis of the lathe spindle of the lathe 1 to ensure that the intermediate cylindrical section 201 of the cylindrical workpiece is coaxial with the spindle of the lathe 1.

[0018] Furthermore, for blanks of different sizes and profiles, the floating conformal positioning cylinder 6 can achieve adaptive fitting with the outer surface of the cylindrical workpiece 2. The floating conformal positioning cylinder 6 has various stroke specifications to meet the adaptive conformal positioning of different profiles.

[0019] Furthermore, the floating conformal positioning cylinder 6 and the active clamping cylinder 5 are arranged at even intervals in the circumferential direction, and the number of the two is equal, so that the cylindrical workpiece is subjected to uniform force and the processing stability is improved.

[0020] Furthermore, the clamping end of the active clamping cylinder 5 is arc-shaped, which can effectively increase the contact area, and it uses a copper base material, which is relatively soft and can reduce scratches.

[0021] Furthermore, the fixture of the present invention uses cylindrical roller bearings 9 to achieve rotary motion. Compared with angular contact ball bearings, cylindrical roller bearings 9 have good pressure bearing performance and improve the reliability of rotation.

[0022] Furthermore, the clamping sequence of the fixture of the present invention is as follows: first, conformal positioning is performed, and then the cylindrical workpiece 2 is clamped. After the floating conformal positioning cylinder 6 conformally contacts the cylindrical workpiece to achieve positioning, the active clamping cylinder 5 performs the clamping action. The conformal positioning of the floating conformal positioning cylinder 6 can effectively enhance the rigidity of the cylindrical workpiece 2 and reduce the clamping deformation caused by the active clamping cylinder 5.

[0023] Furthermore, the number of active clamping cylinders 5 and floating conformal positioning cylinders 6 can be appropriately increased or decreased to meet the needs of different cylinder diameters.

[0024] Furthermore, the PLC control system can be programmed to achieve sequential control of the solenoid valves, thereby enabling one-button automated clamping and release.

[0025] An adaptive conformal centering fixture and automatic clamping method, based on an adaptive conformal centering fixture and a PLC control system, includes the following steps:

[0026] Step 1: Install the adaptive conformal centering fixture on the guide rail of lathe 1, and adjust the position of the outer ring 7 of the fixture to make it coaxial with the spindle of lathe 1.

[0027] Step 2: Adjust the jaws of the four-jaw chuck 3 of the lathe 1 to fix and clamp the cylindrical workpiece 2. At this time, the cylindrical workpiece 2 is located inside the fixture. The floating conformal positioning cylinder 6 and the active clamping cylinder 5 are not energized, that is, the fixture is not in working condition.

[0028] Step 3: Use a dial indicator to check the circular runout of the middle section 201 of the cylindrical workpiece 2, and at the same time adjust the jaws of the four-jaw chuck 3 to make the circular runout of the cylindrical workpiece 2 meet the requirements. At this time, the axis of the cylindrical workpiece 2 coincides with the axis of the spindle of the lathe 1.

[0029] Step 4: Turn the oxides on the outer surface of the A end section 202 and the B end section 203 of the cylindrical workpiece 2 to remove obvious defects from the cylindrical workpiece.

[0030] Step 5: Control the touch panel to circulate oil through the fixture. The floating conformal positioning cylinder 6 extends and clamps the cylindrical workpiece 2 after contacting it, thus realizing the conformal positioning function. After the floating conformal positioning cylinder 6 contacts the cylindrical workpiece 2, set the clamping force and the active clamping cylinder 5 extends to clamp the cylindrical workpiece 2. After the cylindrical workpiece 2 is clamped, remove the four-jaw chuck 3 on one side of the A-end cylindrical section 202.

[0031] Step 6: Machining the inner hole and end face of the A-end section 202 of the cylindrical workpiece 2 until machining is completed;

[0032] Step 7: Use the touch panel to release the hydraulic pressure from the fixture. After the active clamping cylinder 5 and the floating conformal positioning cylinder 6 retract, the cylindrical workpiece 2 is released. Turn the direction of the cylindrical workpiece 2 and use the four-jaw chuck 3 to clamp the cylindrical workpiece 2. Re-perform the circular runout test on the middle section 201 of the cylindrical workpiece 2. At this time, the circular runout measurement is based on the machined part. Adjust the jaws of the four-jaw chuck 3 so that the axis of the cylindrical workpiece 2 coincides with the axis of the lathe spindle 1.

[0033] Step 8: Control the touch panel to circulate oil through the fixture, control the floating conformal positioning cylinder 6 to contact the cylindrical workpiece 2, and after the active clamping cylinder 5 clamps the cylindrical workpiece 2, remove the four-jaw chuck 3 on one side of the B-end cylindrical section 203; process the inner hole and end face of the B-end cylindrical section 203 of the cylindrical workpiece 2; until the B-end cylindrical section 203 of the cylindrical workpiece 2 is processed.

[0034] Step 9: Use the touch panel to release the hydraulic pressure from the fixture, retract the active clamping cylinder 5 and the floating conformal positioning cylinder 6 to release the cylindrical workpiece 2, and complete the entire processing.

[0035] The beneficial effects of this invention are:

[0036] (1) The adaptive conformal centering fixture and automatic clamping method provided by the present invention can replace the traditional process ring clamping method, realize the positioning and clamping of the cylindrical workpiece, eliminate the turning process ring process, and reduce material consumption.

[0037] (2) In the adaptive conformal centering fixture provided in this invention, after the outer ring and cylindrical roller bearing are installed in alignment with the lathe spindle axis, it can be ensured that the intermediate cylinder section coincides with the lathe spindle axis. This replaces the adjustment step of the process ring bolt, greatly reduces the clamping time, and improves the machining efficiency.

[0038] (3) The fixture provided by the present invention achieves conformal positioning of the blank cylindrical workpiece through eight floating conformal positioning cylinders, and clamps the cylindrical workpiece through eight active clamping cylinders, ensuring that the axis of the cylindrical workpiece does not shift while the force is uniform. The top surface of the active clamping cylinder uses an arc-shaped copper column to contact the cylindrical workpiece, which can effectively increase the contact area and contact stiffness, greatly reduce the deformation of the cylindrical workpiece, and improve the machining accuracy.

[0039] (4) The automatic clamping method provided by this invention is based on a PLC control system. It uses the feedback adjustment of the oil pressure gauge and the proportional valve to quantitatively control the clamping force, thereby reducing clamping deformation. One-button automatic clamping and releasing improves clamping efficiency. Attached Figure Description

[0040] Figure 1 This is a lathe mounting diagram of an adaptive conformal centering fixture.

[0041] Figure 2 This is a diagram showing the working state of the fixture.

[0042] Figure 3 It is a traditional ring clamping installation diagram.

[0043] Figure 4 This is an overall drawing of the fixture.

[0044] Figure 5 This is a cross-sectional view of the fixture.

[0045] Figure 6 It is a diagram of the outer ring of the fixture.

[0046] Figure 7 This is a front view of the inner ring of the fixture.

[0047] Figure 8 It is an isometric view of the inner ring of the fixture.

[0048] Figure 9 This is a cross-sectional view of the hydraulic circuit of the active clamping cylinder of the fixture.

[0049] Figure 10 This is a cross-sectional view of the hydraulic circuit of the floating conformal positioning cylinder of the fixture.

[0050] Figure 11 This is the hydraulic circuit diagram of the clamping cylinder for the fixture.

[0051] Figure 12 This is the hydraulic circuit diagram of the floating conformal positioning cylinder of the fixture.

[0052] Figure 13 This is a diagram of the clamping cylinder for active clamping.

[0053] Figure 14 This is a diagram of a cylindrical roller bearing.

[0054] Figure 15 This is a topology diagram of a PLC control system.

[0055] In the diagram: 1. Lathe; 2. Cylindrical workpiece; 3. Four-jaw chuck; 4. Inner ring; 5. Active clamping cylinder; 6. Floating conformal positioning cylinder; 7. Outer ring; 8. End cap; 9. Cylindrical roller bearing; 10. Sealing ring; 11. Tool post; 12. Lathe tool; 13. Process ring; 14. Lifting ring; 15. Rib plate; 201. Intermediate cylinder section; 202. End cylinder section A; 203. End cylinder section B; 401. Active clamping cylinder hydraulic circuit; 402. Floating conformal positioning cylinder hydraulic circuit; 403. First-step ring; 404 Floating conformal positioning cylinder mounting hole; 405 Active clamping cylinder mounting hole; 406 Fourth-step ring; 407 Third-step ring; 408 Second-step ring; 501 Arc-shaped copper pillar; 701 Active clamping cylinder oil inlet; 702 Floating conformal positioning cylinder oil inlet; 703 Oil drain hole; 704 Rectangular base; 705 Inner ring mounting hole; 706 End cap fixing hole; 707 Lifting ring mounting hole; 1301 Small ring; 1302 Process ring bolt; 1303 Large ring. Detailed Implementation

[0056] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings and technical solutions.

[0057] During the fixture installation process, the cylindrical workpiece 2 is made of high-strength alloy and consists of an intermediate cylindrical section 201, an A-end cylindrical section 202, and a B-end cylindrical section 203. The overall length of the cylindrical workpiece is 2200mm. The A-end cylindrical section 202 and the B-end cylindrical section 203 are the sections to be processed, with a diameter of 300mm and a wall thickness of 1mm. The intermediate cylindrical section 201 has a diameter of 150mm.

[0058] First, an adaptive conformal centering automatic fixture is installed, comprising an outer ring 7, an inner ring 4, a floating conformal positioning cylinder 6, an active clamping cylinder 5, and a PLC control system, etc.

[0059] Assemble the outer ring 7: Install the rib plate 15 onto the rectangular base 704 and secure it with bolts. Install the lifting ring 14 into the lifting ring mounting hole 707 of the outer ring 7. At this time, the end cap 8 is not installed.

[0060] Assembly of inner ring 4 and floating conformal positioning cylinder 6: Eight floating conformal positioning cylinders 6 are evenly installed at the floating conformal positioning cylinder mounting holes 404 on the inner ring 4, with the extension direction of the floating conformal positioning cylinder 6 along the radius and pointing towards the center of the circle.

[0061] Assembly of the inner ring 4 and the active clamping cylinders 5: Eight active clamping cylinders 5 are evenly installed at the active clamping cylinder mounting holes 405 on the inner ring 4, and are evenly arranged at intervals with the floating conformal positioning cylinders 6. The extension direction of the active clamping cylinders 5 is along the radius and points towards the center of the circle.

[0062] Assemble the inner ring 4, cylindrical roller bearing 9, and seal ring 10: Assemble the cylindrical roller bearing 9 with the third stepped ring 407 of the inner ring 4. Tightly fit the seal ring 10 with the first stepped ring 403 and the fourth stepped ring 406.

[0063] Assemble the inner ring 4 and outer ring 7: The floating conformal positioning cylinder 6 is interconnected with the floating conformal positioning cylinder oil passage 402. Install the inner ring 4 at the inner ring mounting hole 705 of the outer ring 7. The floating conformal positioning cylinder oil passage 402 of the inner ring 4 is connected to the floating conformal positioning cylinder oil inlet hole 702 on the outer ring 7. The active clamping cylinder 5 is interconnected with the active clamping cylinder oil passage 401. The active clamping cylinder oil passage 401 is connected to the active clamping cylinder oil inlet hole 701 on the outer ring 7. Finally, install the end caps 8 on both sides and fix the end caps 8 to the outer ring 7 with screws, which also serve to fix the inner ring 4.

[0064] PLC control system: according to Figure 15 The PLC control system topology diagram shows the connection between the host computer, controller, touch screen, and connector unit-IO slave station via bus communication. Analog signals from proportional valves, solenoid valves, and pressure gauges are connected to the connector unit-IO slave station. At the drive execution layer, the hydraulic station, proportional valves, solenoid valves, pressure gauges, and adaptive conformal centering fixture are connected sequentially via oil pipes. This completes the connection between the hydraulic circuit and the electrical equipment.

[0065] At this point, the assembly of an adaptive conformal centering automatic fixture is complete.

[0066] The steps for using an adaptive conformal centering automatic fixture and clamping method are as follows:

[0067] Step 1: Install the adaptive conformal centering fixture on the guide rail of lathe 1.

[0068] The assembled fixture is mounted on the guide rail of the lathe 1 via the rectangular base 704 and is located between the four-jaw chucks 3 at both ends of the lathe.

[0069] Step 2: Hoist the cylindrical workpiece 2 above the lathe 1, and adjust the jaws of the four-jaw chucks 3 at both ends of the lathe 1 to clamp the cylindrical workpiece 2.

[0070] The cylindrical workpiece 2 is hoisted above the lathe 1 and placed in the center of the fixture. The jaws of the four-jaw chucks 3 at both ends of the lathe 1 are adjusted to clamp the cylindrical workpiece 2. At this time, the fixture is not energized, and the floating conformal positioning cylinder 6 and the active clamping cylinder 5 are in the retracted state and are not in contact with the cylindrical workpiece 2.

[0071] Step 3: Adjust the axis of the intermediate cylinder section 201 to be concentric with the spindle of the lathe 1, and turn the A-end cylinder section 202 and the B-end cylinder section 203 of the cylinder workpiece 2 to a smooth finish.

[0072] The runout of the intermediate cylindrical section 201 of the cylindrical workpiece 2 is measured using a dial indicator. Simultaneously, the jaws of the four-jaw chucks 3 on both sides of the lathe 1 are adjusted to ensure the runout of the cylindrical workpiece 2 meets the requirements. At this point, the axis of the intermediate cylindrical section 201 coincides with the axis of the lathe 1 spindle. The oxides on the outer surfaces of the A-end cylindrical section 202 and the B-end cylindrical section 203 of the cylindrical workpiece 2 are removed, eliminating any obvious defects in the cylindrical workpiece.

[0073] Step 4: After opening the oil circuit by operating the touch panel to achieve adaptive conformal positioning and active clamping, the A-end section 202 of the cylindrical workpiece 2 is precision machined.

[0074] The touch panel is used to circulate oil through the fixture. The floating conformal positioning cylinder 6 extends and clamps the cylindrical workpiece 2 after contact, achieving conformal positioning. The contact status of the floating conformal positioning cylinder 6 with the cylindrical workpiece 2 can be observed through the hydraulic pressure gauge. Subsequently, the clamping force is input, and the active clamping cylinder 5 is circulated with oil. The active clamping cylinder 5 extends and clamps the cylindrical workpiece 2. The clamping force can be controlled through the hydraulic pressure gauge and proportional valve to achieve active clamping. Finally, the four-jaw chuck 3 at end A of the cylindrical section 202 is removed, and the end face and inner hole of end A of the cylindrical workpiece 2 are machined.

[0075] Step 5: Control the touch panel to stop the oil supply, the floating conformal positioning cylinder 6 and the active clamping cylinder 5 retract and reset, hoist and rotate the cylindrical workpiece 2, adjust the position of the jaws of the four-jaw chuck 3 so that the axis of the intermediate cylinder section 201 is coaxial with the spindle of the lathe 1.

[0076] The touch panel controls the fixture to release the hydraulic pressure, retracting the active clamping cylinder 5 and the floating conformal positioning cylinder 6 to release the cylindrical workpiece 2. The direction of the cylindrical workpiece 2 is reversed, and the inner support of the jaws of the four-jaw chuck 3 is adjusted to clamp the cylindrical workpiece 2. The circular runout of the intermediate cylindrical section 201 of the cylindrical workpiece 2 is re-checked. At this time, the circular runout measurement is based on the machined part. The four-jaw chuck 3 is adjusted so that the axis of the intermediate cylindrical section 201 is coaxial with the spindle of the lathe 1.

[0077] Step 6: The control system of the touch panel opens the oil circuit. After the cylindrical workpiece 2 is adaptively positioned and actively clamped, the B-end section 203 of the cylindrical workpiece 2 is processed.

[0078] The touch panel is used to re-lubricate the fixture, and the floating conformal positioning cylinder 6 extends to contact and clamp the cylindrical workpiece 2. Then, the active clamping cylinder 5 extends to clamp the cylindrical workpiece 2, and the four-jaw chuck 3 at end B of the cylindrical section 203 is removed. The end face and inner hole of end B of the cylindrical workpiece 203 are then machined. At this point, end A of the cylindrical section 202 and end B of the cylindrical workpiece 2 have been fully machined.

[0079] Step 7: Control the touch panel to release the hydraulic pressure of the fixture, retract the active clamping cylinder 5 and the floating conformal positioning cylinder 6 to release the cylindrical workpiece 2, and hoist the cylindrical workpiece 2 to the material warehouse to complete the entire processing process.

[0080] This invention provides an adaptive conformal centering fixture and automatic clamping method that enables adaptive conformal centering clamping of blank cylindrical workpieces without the need for fixture adjustment, simplifying the clamping process and improving machining efficiency through automated clamping. The floating conformal positioning cylinder does not provide active clamping force but has a certain stroke, enabling adaptive conformal positioning for different surface profiles. The active clamping cylinder has a certain stroke and, in conjunction with a pressure gauge and proportional valve, can provide appropriate clamping force for different cylindrical workpieces, reducing clamping deformation. Furthermore, the use of copper pillars on the contact surface of the active clamping cylinder reduces scratches and improves machining accuracy. The use of cylindrical roller bearings provides excellent load-bearing capacity, improving the reliability of the fixture.

[0081] Although embodiments of the present invention have been described in the specification, these embodiments are merely illustrative and should not be construed as limiting the scope of protection of the present invention. Various omissions, substitutions, and modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adaptive conformal centering fixture, characterized in that, The adaptive conformal centering fixture includes an end cap (8), an outer ring (7), a floating conformal positioning cylinder (6), an active clamping cylinder (5), an inner ring (4), a lifting ring (14), a rib plate (15), and a PLC control system; The floating conformal positioning cylinder (6) and the active clamping cylinder (5) are hydraulically driven. The floating conformal positioning cylinder (6) can achieve adaptive conformal positioning of the cylindrical workpiece (2). The active clamping cylinder (5) applies active clamping force to the cylindrical workpiece (2). The floating conformal positioning cylinder (6) first conforms to the shape, and then the active clamping cylinder (5) actively clamps in sequence to achieve adaptive centering clamping. The inner ring (4) is used to install the floating conformal positioning cylinder (6) and the active clamping cylinder (5). The cylindrical roller bearing (9) installed on the outer side of the inner ring (4) realizes the cylindrical workpiece's self-centering clamping. The workpiece (2) is turned and rotated. At the same time, the cylindrical roller bearing (9) is installed in the same position as the lathe spindle to ensure the coaxiality requirement. The end cover (8) realizes the side sealing of the centering fixture. Different oil circuits are arranged in the outer ring (7) to realize sequential clamping. The lifting ring (14) is used for lifting and installation. The rib plate (15) is used to improve the overall rigidity. The PLC control system realizes the sequential control and automatic clamping of the centering fixture. The appropriate clamping force is quantitatively applied to the cylindrical workpiece (2) with different wall thicknesses through the monitoring and adjustment of the oil pressure gauge and proportional valve. The outer ring (7) is a combined structure, divided into upper and lower parts. The upper part is a ring with mounting holes inside. The lower part is a rectangular base (704) for mating with the guide rail of the lathe (1). The connection between the upper ring and the lower rectangular base (704) has an oil inlet and an oil drain hole. The outer ring (7) includes an active clamping cylinder oil inlet (701), a floating conformal positioning cylinder oil inlet (702), an oil drain hole (703), a rectangular base (704), an inner ring mounting hole (705), and an end cap fixing hole. (706) and lifting ring mounting hole (707); the outer ring (7) is mounted on the lathe (1) through the rectangular base (704) to ensure that the axis of the outer ring (7) is consistent with the axis of the spindle of the lathe (1); the inner circumferential surface of the outer ring (7) has an inner ring mounting hole (705), and its outer circumferential surface has an active clamping cylinder oil inlet hole (701), a floating conformal positioning cylinder oil inlet hole (702), an oil drain hole (703) and a lifting ring mounting hole (707), and its outer surface has an end cap fixing hole (706); The inner ring (4) is a stepped ring in the shape of a ring, which contains four stepped segments, namely the first stepped ring (403), the second stepped ring (408), the third stepped ring (407), and the fourth stepped ring (406); the second stepped ring (408), which has the largest diameter, has an active clamping cylinder oil passage (401) and a floating conformal positioning cylinder oil passage (402) that connect the active clamping cylinder oil inlet (701) and the floating conformal positioning cylinder oil inlet (702); the outer side of the widest third stepped ring (407) is used to install cylindrical roller bearings (9), the first... The interior of the three-step ring (407) is evenly distributed with 16 floating conformal positioning cylinder mounting holes (404) and active clamping cylinder mounting holes (405) for installing the active clamping cylinder (5) and the floating conformal positioning cylinder (6); the first step ring (403) and the fourth step ring (406) with the smallest diameter are used to install the sealing ring (10); the inner ring (4) is installed inside the outer ring (7) and fixed by the end cover (8); the cylindrical roller bearing (9) is installed between the outer ring (7) and the inner ring (4) to ensure the centering and rotation of the cylindrical workpiece (2) after clamping.

2. The adaptive conformal centering fixture according to claim 1, characterized in that, The floating conformal positioning cylinder (6) is a hydraulic auxiliary support cylinder driven by oil pressure. There are eight cylinders in total, which are evenly distributed in the mounting holes on the inner ring (4). When hydraulic oil is supplied to the floating conformal positioning cylinder (6) through the oil circuit (402), the support rod extends. After the support rod contacts the workpiece (2) of the cylinder, it automatically clamps, but does not provide clamping force, thereby realizing the conformal positioning function. The active clamping cylinder (5) is a hydraulic clamping cylinder driven by oil pressure. There are eight of them, which are evenly distributed in the mounting holes on the inner ring (4). When hydraulic oil is supplied to the active clamping cylinder (5) through the active clamping cylinder oil circuit (401), the support rod extends. By adjusting the hydraulic oil pressure, different clamping forces can be provided quantitatively to achieve the clamping function. The PLC control system can realize the automated sequential action of the active clamping cylinder (5) and the floating conformal positioning cylinder (6), and is divided into an information control layer and a drive execution layer. The drive execution layer includes a hydraulic station, a proportional valve, a solenoid valve, an oil pressure gauge and an adaptive conformal centering fixture. The drive execution layer is equipped with two sets of proportional valves and solenoid valves, which are used to control the hydraulic oil circuits of the active clamping cylinder (5) and the floating conformal positioning cylinder (6) respectively. Among them, the hydraulic station is used to provide hydraulic oil; the proportional valve can accurately adjust the pressure; the solenoid valve is a switching valve used to control the opening and closing of the oil circuit; the oil pressure gauge is used to detect the clamping force. The information control layer includes a host computer, a controller, a connector unit-IO slave station and a touch screen. Communication adopts the EtherCAT bus method. The connector unit-IO slave station is connected to the proportional valve, the solenoid valve and the oil pressure gauge respectively, and the pressure monitoring is realized by using analog current. The automated sequential clamping and release of this fixture is realized through the PLC control system.

3. The adaptive conformal centering fixture according to claim 2, characterized in that, The hydraulic oil is divided into two paths. One path of hydraulic oil passes through the inlet (702) and oil passage (402) of the floating conformal positioning cylinder and connects to eight floating conformal positioning cylinders (6). The other path of hydraulic oil passes through the inlet (701) and oil passage (401) of the active clamping cylinder and connects to eight active clamping cylinders (5). The two paths of hydraulic oil share a drain hole (703). The eight active clamping cylinders (5) and the eight floating conformal positioning cylinders (6) are connected in series in their respective oil passages to ensure synchronous movement and uniform force on the cylindrical workpiece (2).

4. The adaptive conformal centering fixture according to claim 1, characterized in that, The active clamping cylinder (5) and the floating conformal positioning cylinder (6) are alternately distributed and evenly spaced in the mounting holes in the circumferential direction, and the number of the two is equal. For blanks of different sizes and profiles, the floating conformal positioning cylinder (6) can achieve adaptive fitting with the outer surface of the cylindrical workpiece (2). The floating conformal positioning cylinder (6) has a variety of stroke specifications, which can meet the adaptive conformal positioning of different profiles.

5. The adaptive conformal centering fixture according to claim 1, characterized in that, The oil pressure gauge detects the hydraulic oil pressure and feeds it back to the proportional valve to apply a quantitative clamping force. The oil pressure gauge reading can also accurately detect whether the fixture is in contact with the workpiece.

6. The adaptive conformal centering fixture according to claim 1, characterized in that, When installing the adaptive conformal centering fixture, it is only necessary to align the axis of the outer ring (7) and the cylindrical roller bearing (9) with the axis of the main spindle of the lathe (1) to ensure that the intermediate cylindrical section (201) of the cylindrical workpiece is coaxial with the main spindle of the lathe (1).

7. An automatic clamping method using the adaptive conformal centering fixture according to any one of claims 1-6, characterized in that, The implementation based on an adaptive conformal centering fixture and a PLC control system includes the following steps: Step 1: Install the adaptive conformal centering fixture on the guide rail of the lathe (1) and adjust the position of the outer ring (7) of the fixture to make it coaxial with the spindle of the lathe (1); Step 2: Adjust the jaws of the four-jaw chuck (3) of the lathe (1) to fix and clamp the cylindrical workpiece (2). At this time, the cylindrical workpiece (2) is located inside the fixture. The floating conformal positioning cylinder (6) and the active clamping cylinder (5) are not energized, that is, the fixture is not in working condition. Step 3: Use a dial indicator to check the circular runout of the middle section (201) of the cylindrical workpiece (2), and at the same time adjust the jaws of the four-jaw chuck (3) so that the circular runout of the cylindrical workpiece (2) meets the requirements. At this time, the axis of the cylindrical workpiece (2) coincides with the axis of the lathe spindle (1). Step 4: Turn the oxides on the outer surface of the A end section (202) and the B end section (203) of the cylindrical workpiece (2) to remove obvious defects from the cylindrical workpiece; Step 5: Control the touch panel to circulate oil through the fixture. The floating conformal positioning cylinder (6) extends and clamps the cylindrical workpiece (2) after contacting it, thus realizing the conformal positioning function. After the floating conformal positioning cylinder (6) contacts the cylindrical workpiece (2), set the clamping force and the active clamping cylinder (5) extends to clamp the cylindrical workpiece (2). After the cylindrical workpiece (2) is clamped, remove the four-jaw chuck (3) on one side of the A-end cylindrical section (202). Step 6: Machining the inner hole and end face of the A-end section (202) of the cylindrical workpiece (2) until machining is completed; Step 7: Use the touch panel to release the hydraulic pressure of the fixture, and release the cylindrical workpiece (2) after the active clamping cylinder (5) and the floating conformal positioning cylinder (6) retract; turn the direction of the cylindrical workpiece (2), and use the four-jaw chuck (3) to clamp the cylindrical workpiece (2) in the inner support. Re-perform the circular runout test on the middle section (201) of the cylindrical workpiece (2). At this time, the circular runout measurement is based on the machined part. Adjust the jaws of the four-jaw chuck (3) to make the axis of the cylindrical workpiece (2) coincide with the axis of the lathe (1) spindle. Step 8: Control the touch panel to circulate oil through the fixture, control the floating conformal positioning cylinder (6) to contact the cylindrical workpiece (2), and after the active clamping cylinder (5) clamps the cylindrical workpiece (2), remove the four-jaw chuck (3) on one side of the B-end cylindrical section (203); process the inner hole and end face of the B-end cylindrical section (203) of the cylindrical workpiece (2); until the B-end cylindrical section (203) of the cylindrical workpiece (2) is processed; Step 9: Use the touch panel to release the hydraulic pressure from the fixture, retract the active clamping cylinder (5) and the floating conformal positioning cylinder (6) to release the cylindrical workpiece (2), and complete the entire processing.

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