Hydraulic-assisted single-point incremental forming device and method for thin-wall metal parts

Abstract

The invention discloses a thin-wall metal part hydraulic auxiliary single-point increment forming device and method, and belongs to the technical field of metal plate increment. The device comprises a detachable sealing clamp used for clamping a plate to be machined, a spherical cutter connected with a main shaft of the vertical machining center, a hydraulic auxiliary assembly communicated with a sealing cavity, and a control unit used for regulating and controlling cutter movement and static pressure output in a linkage mode. The method comprises the four steps of clamp assembling and plate fixing, hydraulic pre-bulging, parameter setting and static pressure preparation and incremental forming and aftertreatment. The technical problems that multiple times of clamping are needed, the forming quality is poor and the efficiency is low when the special-shaped curved-surface thin-wall complex feature part is machined through traditional single-point incremental forming are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of incremental forming of metal plates, and particularly relates to a thin-walled metal part hydraulic auxiliary single-point incremental forming device and a thin-walled metal part hydraulic auxiliary single-point incremental forming method. BACKGROUND

[0002] Single-point incremental forming (SPIF) is a flexible forming technology based on the idea of layered manufacturing, which realizes three-dimensional part processing by controlling the tool head to extrude the metal plate point by point, has the advantages of no need for special molds, low cost and high flexibility, and is widely used in small-batch complex part manufacturing in the fields of aerospace, automobiles, medical treatment and the like. However, with the rapid development of the aerospace, automobile and other industries, the personalized, diversified and customized demands for various curved thin-walled metal parts are increasing.

[0003] The prior art has the following key defects: when the traditional SPIF processes complex parts, the back of the plate has no effective support, stress concentration is prone to occur, leading to cracking and springback, and the forming precision is difficult to meet the requirements of aerospace parts; for parts containing multiple convex-concave features, ridge features and local severe curvature changes, the traditional SPIF needs multiple clamping and multiple forming, resulting in complex process, long processing cycle and high cost; the existing auxiliary methods such as simple hydraulic bulging are only used for preforming, which is prone to cause uneven thinning of the plate; the flexible support such as magneto-rheological elastomer can adjust the rigidity, but for double-curved ridge features, the pressure transmission uniformity is poor, and it is difficult to adapt to the local deformation demand. Therefore, it is an urgent problem for the technology to quickly and accurately process curved thin-walled metal parts through process compounding. SUMMARY

[0004] The first object of the present application is to provide a thin-walled metal part hydraulic auxiliary single-point incremental forming device, which solves the technical problem that the back of the plate has no effective support, stress concentration is prone to occur, leading to cracking and springback, and the forming precision is difficult to meet.

[0005] The second object of the present application is to provide a thin-walled metal part hydraulic auxiliary single-point incremental forming method, which solves the technical problem that the traditional single-point incremental forming needs multiple clamping and multiple forming, resulting in complex process.

[0006] The first technical solution of the present application is a thin-walled metal part hydraulic auxiliary single-point incremental forming device, which comprises a detachable sealing clamp for clamping a to-be-processed plate, a sealing cavity for accommodating hydraulic oil is formed between the inside of the detachable sealing clamp and the to-be-processed plate, and the sealing cavity is connected with a hydraulic auxiliary assembly through a high-pressure hose; a cutter for extruding and forming the to-be-processed plate is arranged at the top of the detachable sealing clamp, the tail end of the cutter is connected with a main shaft of a vertical machining center, the hydraulic auxiliary assembly is electrically connected with a control unit of the vertical machining center, and the control unit is used for linkage control of cutter movement of the vertical machining center and static pressure output of the hydraulic auxiliary assembly.

[0007] The first technical solution of the present application is also characterized by: The detachable sealing clamp is composed of an upper clamp and a lower clamp connected by threads, and the to-be-processed plate is clamped between the upper clamp and the lower clamp.

[0008] The cutter is a spherical structure, the material is X210CrW12 high-speed steel, and the axis of the cutter is perpendicular to the upper surface of the to-be-processed plate.

[0009] The hydraulic auxiliary assembly comprises a pressure control unit connected with the sealing cavity through a high-pressure hose, the pressure control unit comprises an oil tank and a leak-free electromagnetic valve, the oil tank and the leak-free electromagnetic valve are connected through a first pipeline and a second pipeline, an air filter, a suction filter and an axial plunger pump are connected in series along the fluid flow direction on the first pipeline, a second gas-liquid accumulator and an overflow valve are connected in series through a third pipeline on the second pipeline, and a third pressure gauge is installed on the third pipeline. The oil tank is connected with a liquid level and temperature meter, a three-phase asynchronous motor is connected with the axial plunger pump, a check valve is installed between the axial plunger pump and the leak-free electromagnetic valve on the first pipeline, and a needle-shaped stop valve is connected between the leak-free electromagnetic valve and the high-pressure hose through a third pipeline.

[0010] The hydraulic auxiliary assembly further comprises a pressure stabilizing unit connected with the third pipeline through a fourth pipeline, the pressure stabilizing unit comprises an air storage tank and a first gas-liquid accumulator, the first gas-liquid accumulator is connected with the needle-shaped stop valve, a precision pressure reducing valve is connected between the air storage tank and the first gas-liquid accumulator; a water separation filter is connected between the precision pressure reducing valve and the air storage tank, the air storage tank and the first gas-liquid accumulator are connected through a plastic air pipe, a right-angle needle valve is installed on the pipeline between the precision pressure reducing valve and the first gas-liquid accumulator, a second pressure gauge is installed on the precision pressure reducing valve, and a first pressure gauge is installed on the first gas-liquid accumulator.

[0011] The second technical solution of the present application is a thin-walled metal part hydraulic auxiliary single-point incremental forming method, which adopts the thin-walled metal part hydraulic auxiliary single-point incremental forming device described above, and comprises the following steps: S1: Install the clamp to the machining center, connect the hydraulic auxiliary assembly, fix the plate to be machined and align the cutter, and apply lubricating oil on the upper surface of the plate; S2: Start the hydraulic auxiliary assembly to raise the pressure in the sealed cavity to 1.5-3 MPa, maintain the pressure for 5-10 s, monitor the pressure and deformation of the plate to be machined during the process, and release the pressure after pre-expansion; S3: Parameter setting and static pressure preparation, generate spiral machining trajectory, establish linear relationship between static pressure P and machining depth Z and input the control unit, adjust the static pressure to the preset value; S4: The cutter forms layer by layer along the spiral machining trajectory, releases the pressure after forming and takes out the formed part for detection.

[0012] The second technical solution of the application also has the following characteristics: S1 specifically: The lower clamp of the detachable sealing clamp is fixed to the workbench of the vertical machining center, the upper clamp is threadedly connected with the lower clamp, and the two form a sealed cavity with a rubber sealing groove; the plate to be machined with a thickness of 0.8-1.2 mm is clamped between the upper clamp and the lower clamp, and is tightened to ensure that the sealed cavity is leak-free; the relative position of the cutter and the plate to be machined is calibrated by the machining center to avoid cutter collision during machining, and then metalworking lubricating oil is uniformly applied on the upper surface of the plate.

[0013] S2 specifically: Start the three-phase asynchronous motor to drive the axial plunger pump, open the leak-free electromagnetic valve to deliver hydraulic oil to the sealed cavity, and adjust the overflow valve to raise the pressure in the sealed cavity to 1.5-3 MPa; open the second gas-liquid accumulator to absorb pressure fluctuations in the oil circuit, monitor the pressure in real time through the first pressure gauge during the pressure maintaining period of 5-10 s, and observe the pre-deformation state of the plate to be machined synchronously; after pre-expansion, close the leak-free electromagnetic valve and open the needle-shaped stop valve to release the pressure to zero.

[0014] S3 specifically: Generate the spiral machining trajectory of the plate to be machined through the machining trajectory control unit, set the parameters of the spherical cutter; based on the deformation requirements of the special-shaped features of the plate to be machined, establish the linear relationship between the static pressure P and the machining depth Z and input the control unit; start the air storage tank, compress the air after purification by the water separation filter, adjust it to the preset static pressure value through the precision pressure reducing valve, and confirm the pressure through the second pressure gauge.

[0015] S4 specifically: Start the vertical machining center, the cutter extrudes and forms the plate to be machined layer by layer along the preset spiral trajectory, the first gas-liquid accumulator continuously provides static pressure support and maintains pressure during the machining process; after forming, close the machining center and the hydraulic auxiliary system, and open the needle-shaped stop valve to completely release the pressure; disassemble the upper clamp to take out the formed part, detect the special-shaped feature size of the formed part using the Hexagon IRP40.02 infrared photoelectric probe, and detect the thickness of different areas of the formed part using the double-tipped micrometer.

[0016] The beneficial effects of the present application are: The detachable sealing clamp of the present application realizes single clamping of the plate to be processed, saves the traditional multiple clamping steps, and improves the efficiency; the hydraulic auxiliary assembly accurately controls the static pressure of the sealing cavity, cooperates with the gas-liquid accumulator to stabilize the pressure, and reduces the cracking and rebound of the plate; the control unit links the tool movement and the static pressure output to ensure the forming precision of the special-shaped curved surface. In the forming step, the clamping is convenient and reliable, the hydraulic pre-expansion lays a foundation for uniform deformation for subsequent forming, and the spiral trajectory layer-by-layer forming makes the feature profile smooth. The present application solves the problems of low efficiency and poor precision in traditional processing, is suitable for small-batch manufacturing of thin-walled complex parts of different materials, and has significant technical advantages. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 Fig. 1 is a structural schematic diagram of the thin-walled metal part hydraulic auxiliary single-point incremental forming device of the present application; Fig. 2 Fig. 2 is a structural schematic diagram of the hydraulic auxiliary system in the thin-walled metal part hydraulic auxiliary single-point incremental forming device of the present application; Fig. 3 Fig. 3 is a feature diagram of the thin-walled metal part in the thin-walled metal part hydraulic auxiliary single-point incremental forming device of the present application.

[0018] In the figure: 1. aluminum plate, 2. tool, 3. hydraulic oil, 4. upper clamp, 5. lower clamp, 6. oil tank, 7. liquid level and temperature gauge, 8. axial plunger pump, 9. one-way valve, 10. overflow valve, 11. leak-free electromagnetic valve, 12. needle-shaped stop valve, 13. high-pressure hose, 14. No. 1 pressure gauge, 15. first gas-liquid accumulator, 16. right-angle needle valve, 17. No. 2 pressure gauge, 18. precision pressure reducing valve; 19. water separation filter, 20. plastic air pipe, 21. air storage tank, 22. second gas-liquid accumulator, 23. No. 3 pressure gauge, 24. three-phase asynchronous motor, 25. suction filter, 26. air filter, 101. concave feature, 102. convex feature, 103. ridge feature. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0020] Embodiment 1 As Figs. 1-3As shown, the thin-walled metal parts hydraulically assisted single-point incremental forming device disclosed in this invention includes a detachable sealing fixture for clamping the sheet metal 1 to be processed. A sealed cavity for containing hydraulic oil is formed between the interior of the detachable sealing fixture and the sheet metal 1 to be processed. The sealed cavity is connected to a hydraulic auxiliary component through a high-pressure hose 13. A cutting tool 2 for extruding and forming the sheet metal 1 to be processed is provided at the top of the detachable sealing fixture. The tail end of the cutting tool 2 is connected to the spindle of a vertical machining center. The hydraulic auxiliary component is electrically connected to a control unit of the vertical machining center. The control unit is used to coordinate and control the movement of the cutting tool of the vertical machining center and the static pressure output of the hydraulic auxiliary component.

[0021] This embodiment 1, based on the coordinated control of hydraulic assisted support and single-point incremental forming, aims to solve the problems of insufficient support on the back of the sheet metal, easy cracking and springback, and the need for multiple clamping when processing complex features using traditional single-point incremental forming (SPIF). The detachable sealing fixture serves as the core load-bearing structure. On one hand, it ensures stable clamping of the sheet metal 1 to be processed, preventing displacement during processing and thus avoiding deviations in forming accuracy. On the other hand, the sealed cavity formed by the fixture and the sheet metal 1 provides a sealed space for hydraulic oil, ensuring that the static pressure output by the hydraulic auxiliary component is evenly applied to the back of the sheet metal. The high-pressure hose 13 serves as a fluid transmission channel, connecting the sealed cavity and the hydraulic auxiliary component, ensuring stable delivery of hydraulic oil or static pressure. The cutting tool 2, as the forming execution component, is connected to the spindle of a vertical machining center and can, under the drive of the spindle, extrude the sheet metal 1 point by point and layer by layer, thereby forming a shape such as... Fig. 3 The target irregular curved surface shown includes concave feature 101, convex feature 102, and ridge feature 103. The control unit, as the core control module, establishes an electrical connection with the hydraulic auxiliary component and the vertical machining center. It can simultaneously receive the real-time motion parameters of the tool 2 (such as machining depth and trajectory position) fed back by the vertical machining center, and send hydrostatic adjustment signals to the hydraulic auxiliary component to achieve precise linkage between the tool motion trajectory and the hydrostatic support on the back of the sheet metal. This ensures that the sheet metal 1 to be processed can obtain appropriate hydrostatic support at different processing stages, ultimately improving the forming quality and efficiency of the irregular curved thin-walled parts.

[0022] Example 2 Based on Example 1, the detachable sealing clamp is composed of an upper clamp 4 and a lower clamp 5 connected by threads.

[0023] The stable clamping of the plate to be processed 1 and the reliable sealing of the sealed cavity are realized by threaded connection, which provides basic conditions for hydraulic auxiliary static pressure support; wherein the upper clamp 4 and the lower clamp 5 adopt a split structure connected by threads, which facilitates the clamping of the plate to be processed 1 and the disassembly of the formed part, and solves the problem of inconvenient operation of the integral clamp; the threaded connection can uniformly transmit the clamping force to the edge area of the plate to be processed 1, avoiding the pre-deformation of the plate caused by excessive local clamping force, or the displacement of the plate to be processed 1 during processing caused by insufficient clamping force, thereby ensuring the forming precision; the upper clamp 4 is connected with the lower clamp 5 by threads, on the one hand, the self-locking property of the threads ensures that the clamp always remains fastened during processing, preventing clamping loosening caused by vibration, on the other hand, the degree of tightening can be adjusted to adapt to the clamping needs of plates to be processed 1 of different thicknesses, while ensuring the fit between the upper clamp 4, the lower clamp 5 and the plate to be processed 1, providing necessary sealing protection for the subsequent sealed cavity containing hydraulic oil and maintaining stable static pressure.

[0024] Further, the tool 2 is a spherical structure, and the material is X210CrW12 high-speed steel. The axis of the tool 2 is perpendicular to the upper surface of the plate to be processed 1.

[0025] Further limit the structure, material and installation attitude of the tool 2, optimize the action form of the tool 2 and the plate to be processed 1, improve the tool durability, and ensure the accurate transmission of extrusion force, adapt to the high-precision forming needs of special-shaped curved surface thin-walled parts; wherein the tool 2 adopts a spherical structure, which has the advantage that in the single-point incremental forming process, the contact between the spherical surface and the plate to be processed 1 is surface contact (compared to point contact of sharp tools), which can effectively disperse the extrusion stress, avoid cracks, wrinkles and other defects of the plate to be processed 1 caused by local stress concentration, and more evenly push the plate to be processed 1 to deform plastically, ensuring the smoothness of the special-shaped curved surface profile; the tool 2 is made of X210CrW12 high-speed steel, which has high hardness, high wear resistance and good hardenability, can withstand the friction and wear caused by repeated extrusion of the tool and the plate during processing, avoid the size precision of the tool to be reduced due to wear, and thus ensure the consistency of batch forming parts; the perpendicular installation of the axis of the tool 2 to the upper surface of the plate to be processed 1 can make the extrusion force of the tool 2 on the plate to be processed 1 be accurately transmitted along the normal direction of the plate to be processed 1, prevent the plate to be processed 1 from deforming laterally due to the eccentric load of the action force, and ensure that the depth and profile of each layer of extrusion forming are consistent with the preset trajectory, providing a reliable execution basis for the subsequent control unit to link and control the tool movement and static pressure output to realize high-quality special-shaped curved surface forming.

[0026] Embodiment 3 On the basis of embodiment 1, the hydraulic auxiliary assembly comprises a pressure regulating unit communicated with the sealed cavity through the high-pressure hose 13, the pressure regulating unit comprising an oil tank 6 and a leakage-free electromagnetic valve 11, the oil tank 6 and the leakage-free electromagnetic valve 11 being communicated through a first pipeline and a second pipeline, the first pipeline being provided with an air filter 26, a suction filter 25 and an axial piston pump 8 in sequence along the fluid flow direction, the second pipeline being communicated with an overflow valve 10 and a second gas-liquid accumulator 22 through a third pipeline, the third pipeline being further provided with a third pressure gauge 23; Wherein, the oil tank 6 is connected with a liquid level and temperature gauge 7, the axial piston pump 8 is connected with a three-phase asynchronous motor 24, a one-way valve 9 is installed between the axial piston pump 8 and the leakage-free electromagnetic valve 11 on the first pipeline, and a needle-shaped stop valve 12 is communicated between the leakage-free electromagnetic valve 11 and the high-pressure hose 13 through the third pipeline.

[0027] The oil tank 6 serves as a storage and supply source of hydraulic oil, and the liquid level and temperature gauge 7 connected thereto can monitor the oil level and oil temperature in real time, avoiding damage of the axial piston pump 8 due to low oil level or abnormal deformation of the plate 1 to be processed due to sudden pressure drop of the sealed cavity; the air filter 26 and the suction filter 25 connected in sequence along the fluid flow direction of the first pipeline form a “double filtration” mechanism, the air filter 26 prevents dust and impurities in the external air from entering the oil tank 6 to pollute the oil, and the suction filter 25 filters the particulate impurities in the oil to avoid the impurities from entering the axial piston pump 8 to cause piston wear or jam, thereby ensuring stable operation of the power source; the axial piston pump 8 serves as a core power component of the hydraulic system, and provides driving force through the three-phase asynchronous motor 24 to pressurize the low-pressure oil in the oil tank 6 into high-pressure oil, thereby providing pressure basis for the sealed cavity; the one-way valve 9 on the first pipeline between the axial piston pump 8 and the leakage-free electromagnetic valve 11 can realize one-way conduction of the oil circuit, preventing the high-pressure oil from flowing back to the axial piston pump 8 to cause pump body reversal or pressure loss, thereby ensuring stable pressure of the oil circuit; the leakage-free electromagnetic valve 11 serves as a control core of the oil circuit on-off, and can accurately switch the “on / off” state of the oil circuit according to the signal of the control unit, thereby realizing on-demand delivery of the hydraulic oil to the sealed cavity; the second pipeline and the third pipeline constitute a pressure regulating and buffering branch, wherein the overflow valve 10 can stabilize the oil circuit pressure in a preset range of 1.5-3 MPa, and automatically overflow and release pressure when the pressure exceeds the set value, thereby avoiding system overpressure damage; the third pressure gauge 23 on the third pipeline can feed back the oil circuit pressure value in real time, thereby providing pressure monitoring basis for the control unit or the operator, and the second gas-liquid accumulator 22 can absorb the pulsation of the output pressure of the axial piston pump 8, thereby reducing the pressure fluctuation of the oil circuit and ensuring that the sealed cavity obtains stable pressure supply; the needle-shaped stop valve 12 communicated between the leakage-free electromagnetic valve 11 and the high-pressure hose 13 can realize fine flow regulation or emergency shutdown of the oil circuit, for example, adjusting the opening degree to control the pressure release speed after the pre-forming is completed, thereby avoiding abnormal deformation of the plate 1 to be processed due to sudden pressure drop of the sealed cavity, and providing oil circuit shutdown guarantee for system maintenance.

[0028] Example 4 On the basis of example 1, the hydraulic auxiliary assembly further comprises a pressure stabilizing unit in communication with the third pipeline through a fourth pipeline, the pressure stabilizing unit comprising an air storage tank 21 and a first gas-liquid accumulator 15, the first gas-liquid accumulator 15 being in communication with the needle-shaped stop valve 12, a precision pressure reducing valve 18 being in communication between the air storage tank 21 and the first gas-liquid accumulator 15; wherein a water separation filter 19 is in communication between the precision pressure reducing valve 18 and the air storage tank 21, a plastic air pipe 20 being in communication between the water separation filter 19 and the air storage tank 21, a right-angle needle valve 16 being installed on the pipeline between the precision pressure reducing valve 18 and the first gas-liquid accumulator 15, a second pressure gauge 17 being installed on the precision pressure reducing valve 18, and a first pressure gauge 14 being installed on the first gas-liquid accumulator 15.

[0029] The air storage tank 21 serves as a gas source storage component for static pressure support, can store compressed air and maintain stable basic air pressure, and avoids direct influence of air source pressure fluctuation on the static pressure of the sealed cavity; the plastic air pipe 20 serves as a transmission channel for compressed air, has good flexibility and sealing performance, is suitable for the installation layout between the hydraulic auxiliary assembly and the clamp, and ensures no leakage of the air source transmission; the water separation filter 19 between the precision pressure reducing valve 18 and the air storage tank 21 can filter water and solid impurities in the compressed air, prevents water corrosion of the pipeline and impurities from blocking the valve core of the precision pressure reducing valve 18, and ensures stable operation of subsequent pressure regulating components; the precision pressure reducing valve 18 is a core component for static pressure precise control, can regulate the air pressure output by the air storage tank 21 to a preset static pressure value (such as 0.03-0.3 MPa) suitable for the machining depth, the second pressure gauge 17 installed thereon can feed back the pressure value after regulation in real time, and provides a pressure calibration basis for the operator or the control unit; the right-angle needle valve 16 between the precision pressure reducing valve 18 and the first gas-liquid accumulator 15 can realize on-off control and fine flow regulation of the static pressure pipeline, is convenient for static pressure preset debugging before forming, can also cut off the pipeline during system maintenance, and ensures operation safety; the first gas-liquid accumulator 15 serves as a pressure pulsation absorbing component, can buffer pressure fluctuation in the compressed air transmission process, quickly supplements or absorbs pressure when the sealed cavity has a slight volume change due to deformation of the plate, and maintains stable static pressure, the first pressure gauge 14 installed thereon can monitor the static pressure value entering the sealed cavity in real time, and ensures consistency of the correlation between the static pressure P and the machining depth Z preset by the control unit; and the communication design of the first gas-liquid accumulator 15 and the needle-shaped stop valve 12 can realize connection of the oil circuit for “hydraulic pre-expansion” and “static pressure support”, the static pressure pipeline is cut off by the needle-shaped stop valve 12 in the pre-expansion stage, the static pressure is conducted in the forming stage, and orderly switching of the two pressure working conditions is ensured.

[0030] Example 5 The application further discloses a thin-wall metal part hydraulic auxiliary single-point incremental forming method. S1: detachable sealing clamps are installed on a machining center, pipes of a hydraulic auxiliary assembly are connected, a plate to be machined is fixed, tool setting is completed, and metal machining lubricating oil is applied on the upper surface of the plate; S2: the hydraulic auxiliary assembly is started to make the pressure in the sealing cavity rise to 1.5-3 MPa, the pressure is kept for 5-10 seconds, the pressure and deformation of the plate to be machined are monitored in the process, and the pressure is released after pre-expansion; S3: parameter setting and static pressure preparation, a helical machining track is generated through a machining track control unit, a linear correlation between static pressure P and machining depth Z is established and input into a control unit, and the static pressure is adjusted to a preset value; S4: the cutter 2 is formed along the helical machining track layer by layer, the pressure is released after forming, and the formed part is taken out, and the size and thickness of the formed part are detected.

[0031] Through the staged process design of "pretreatment-pre-expansion-parameter setting-post-forming treatment", the problems of multiple clamping and easy cracking and rebounding of the plate in traditional single-point incremental forming are solved, and single clamping high-quality forming of a complex feature part is realized.

[0032] Example 6 On the basis of example 5, S1 is specifically: the lower clamp 5 of the detachable sealing clamp is fixed on the workbench of the vertical machining center, the upper clamp 4 and the lower clamp 5 are connected through threads, and the two form a sealing cavity with a rubber sealing groove; the plate to be machined with a thickness of 0.8-1.2 mm is clamped between the upper clamp 4 and the lower clamp 5, and is screwed to ensure that the sealing cavity has no leakage; the relative positions of the cutter 2 and the plate to be machined are calibrated through tool setting of the machining center, so that tool collision in the machining process is avoided, and then metal machining lubricating oil is uniformly applied on the upper surface of the plate.

[0033] The lower clamp 5 of the detachable sealing clamp is fixed on the workbench of the vertical machining center, relying on the high-precision positioning reference of the workbench of the machining center to determine the spatial position of the clamp as a whole, avoiding the relative deviation of the subsequent tool 2 movement trajectory and the clamp, providing basic positioning guarantee for forming precision; the upper clamp 4 and the lower clamp 5 are connected through threads, which can not only make the clamping force uniformly transmitted along the edge of the plate to prevent the pre-deformation of the plate to be processed 1 caused by uneven local stress, but also ensure that the clamp remains fastened during the machining process through the self-locking characteristics of the threaded connection, and the sealing cavity with a rubber sealing groove formed by the two can fill the small gap between the clamp and the plate to be processed 1 by the elastic fitting characteristics of the rubber sealing groove, providing the necessary sealing conditions for the subsequent hydraulic oil 3 storage and static pressure maintenance, avoiding pressure leakage affecting the process effect; the plate to be processed 1 with a thickness of 0.8-1.2mm is clamped between the upper and lower clamps and tightened to ensure that the sealing cavity has no leakage, because this thickness range is suitable for the design size of the clamp sealing groove, and the tightening operation can further strengthen the adhesion of the plate and the clamp, so that the plate becomes part of the sealing cavity, ensuring that the pressure can act uniformly on the back of the plate during the subsequent hydraulic pre-expansion; the relative position of the tool 2 and the plate to be processed 1 is calibrated by the machining center, which uses the numerical control positioning function of the machining center to accurately determine the initial distance between the tool tip of the tool 2 and the upper surface of the plate to be processed 1, avoiding collision between the tool 2 and the plate to be processed 1 in the early stage of machining, damaging the tool 2 or the plate to be processed 1, and ensuring that the generated spiral machining trajectory can accurately match the machining area of the plate to be processed 1; evenly applying metalworking lubricating oil on the upper surface of the plate to be processed 1 can form a lubricating film on the contact surface between the tool 2 and the plate, reducing the friction resistance between them, reducing the risk of scratches on the surface of the plate to be processed 1 caused by friction, and reducing the driving force required for extrusion forming of the tool 2, improving the stability of the forming process, and adapting to the process characteristics of single-point incremental forming and layer-by-layer extrusion.

[0034] S2 is specifically: start the three-phase asynchronous motor 24 to drive the axial plunger pump 8, open the no-leakage electromagnetic valve 11 to transport hydraulic oil 3 to the sealing cavity, adjust the overflow valve 10 to make the pressure in the sealing cavity rise to 1.5MPa-3MPa; open the second gas-liquid accumulator 22 to absorb the pressure fluctuation of the oil circuit, during the pressure maintaining period of 5s-10s, monitor the pressure in real time through the first pressure gauge 14, and observe the pre-deformation state of the plate to be processed 1 synchronously; after the pre-expansion is completed, close the no-leakage electromagnetic valve 11, and open the needle-shaped stop valve 12 to release pressure to zero the reading of the first pressure gauge 14.

[0035] The three-phase asynchronous motor 24 drives the axial piston pump 8 because the three-phase asynchronous motor 24 can provide continuous and stable driving force to drive the axial piston pump 8 to pressurize the low-pressure hydraulic oil 3 in the oil tank 6 into high-pressure oil, and the axial piston pump 8 has high-pressure output precision and stability, which can meet the demand of the sealing cavity for 1.5-3 MPa high-pressure oil source, and provide sufficient pressure basis for plate deformation; opening the no-leakage electromagnetic valve 11 uses its no-leakage characteristic to ensure that the high-pressure oil can be completely delivered to the sealing cavity, avoiding pressure loss due to oil line leakage, and thus failing to reach the preset pre-expansion pressure; adjusting the overflow valve 10 to make the pressure in the sealing cavity rise to 1.5-3 MPa because the overflow valve 10 can realize precise pressure control through valve core opening degree adjustment, and automatically overflow and decompress when the oil line pressure exceeds the set value, preventing system overpressure damage, and at the same time stabilizing the pressure in the range suitable for the initial deformation of the to-be-processed plate 1 (thickness 0.8-1.2 mm), avoiding that the pressure is too low to form effective pre-deformation or the pressure is too high to cause the to-be-processed plate 1 to break; opening the second gas-liquid accumulator 22 uses its energy storage and buffering characteristics to absorb the pulsation of the output pressure of the axial piston pump 8, reduces the pressure fluctuation of the oil line, ensures that the hydraulic oil 3 in the sealing cavity has uniform and constant pressure on the to-be-processed plate 1, and avoids that the local deformation of the plate is uneven due to pressure pulsation; monitoring the pressure through the first pressure gauge 14 during the pressure maintaining period of 5-10 seconds is to directly confirm whether the pressure in the sealing cavity is continuously and stably maintained in the preset range, and to synchronously observe the pre-deformation state of the to-be-processed plate 1, so as to judge whether the to-be-processed plate 1 has generated the expected initial plastic deformation (such as adhering to the profile of the sealing cavity of the clamp) through vision, avoiding blind pressure maintaining; closing the no-leakage electromagnetic valve 11 after pre-expansion is completed, which can cut off the high-pressure oil delivery line, prevent the oil in the oil tank 6 from flowing back during the subsequent pressure relief process, open the needle-shaped stop valve 12 to relieve pressure to zero reading of the first pressure gauge 14, because the needle-shaped stop valve 12 has a fine flow adjustment function, which can realize slow pressure relief, avoid that the to-be-processed plate 1 is deformed abnormally due to elastic rebound caused by sudden pressure drop of the sealing cavity, and clear the pressure interference for subsequent switching to the static pressure support working condition, ensuring the accuracy of subsequent static pressure control in the forming stage.

[0036] S3 is specifically: generating the spiral machining track of the to-be-processed plate 1 through a machining track control unit, and setting the parameters of the spherical cutter 2; based on the deformation demand of the special-shaped feature of the to-be-processed plate 1, a linear correlation between the static pressure P and the machining depth Z is established and input into the control unit; starting the air storage tank 21, and after the compressed air is purified through the water diversion filter 19, it is adjusted to a preset static pressure value through the precise pressure reducing valve 18, and the pressure is confirmed to meet the standard by the second pressure gauge 17.

[0037] The spiral machining track of the plate to be machined 1 is generated by the machining track control unit, which is suitable for single-point incremental forming "layer-by-layer cumulative plastic deformation" process characteristics, can make the spherical cutter 2 uniformly cover the plate machining area along the preset path, especially suitable for complex profiles of concave features 101, convex features 102 and ridge features 103, and avoid forming defects caused by track breakpoints; The parameters of the spherical cutter 2 (such as diameter 8-12 mm, feed speed, etc.) are set to match the cutter motion parameters with the spiral track and the plate thickness (0.8-1.2 mm), to ensure uniform extrusion deformation of each layer and prevent local thinning or insufficient deformation of the plate due to improper cutter parameters; The linear relationship between static pressure P and machining depth Z is established based on the deformation requirements of the special-shaped features of the plate to be machined 1, because the greater the machining depth (such as the deep cavity area of the ridge feature 103), the greater the tensile stress on the back of the plate, and the static pressure P needs to be increased simultaneously to balance the stress and prevent cracking. By inputting this correlation into the control unit, the "cutter machining depth change-static pressure real-time adjustment" linkage can be realized during subsequent forming, avoiding the lag caused by manual intervention; The air storage tank 21 is started to provide a stable air source for static pressure support. Compressed air is purified by the water separation filter 19, which can filter out water and solid impurities in the air to prevent water corrosion of the pipeline and impurities from jamming the precision pressure reducing valve 18 core, and to ensure the stable operation of the static pressure control components; The preset static pressure value (such as 0.03-0.3 MPa) is adjusted by the precision pressure reducing valve 18, which uses its high-precision pressure regulating characteristics to ensure that the static pressure can accurately match the correlation requirements of static pressure P-machining depth Z, and the second pressure gauge 17 is used to feedback the adjusted static pressure value in real time. After confirming that the pressure meets the standard, it enters the subsequent forming stage, which can avoid the forming quality problems caused by insufficient or excessive static pressure.

[0038] S4 specifically: start the vertical machining center, the cutter 2 along the preset spiral track to the plate to be machined 1 layer-by-layer extrusion forming, the first gas-liquid accumulator 15 continuously provides static pressure support and maintains pressure holding state during machining; After forming is completed, the machining center and hydraulic auxiliary system are closed, and the needle-shaped stop valve 12 is opened to completely release pressure; disassemble the upper clamp 4 to take out the formed part, use the Hexagon IRP40.02 infrared photoelectric probe to detect the special-shaped feature size of the formed part, and use the double-tip micrometer to detect the thickness of different areas of the formed part.

[0039] The vertical machining center is started to make the tool 2 extrude the plate 1 along the preset spiral trajectory to form a layer by layer, because the spiral trajectory is suitable for the characteristics of single-point incremental forming "layer by layer cumulative plastic deformation", which can make the spherical tool 2 (X210CrW12 high-speed steel material, diameter 8-12mm) uniformly act on each area of the plate, avoid local deformation overload leading to cracking, and "layer by layer extrusion" can accurately control the deformation of each layer, and ensure the contour accuracy of special features (concave features 101, convex features 102, ridge features 103); the first gas-liquid accumulator 15 continuously provides static pressure support and maintains pressure during the machining process, which uses its energy storage buffer characteristics to quickly supplement or absorb pressure when the volume of the sealed cavity changes slightly due to extrusion deformation, to maintain stable static pressure and avoid uneven springback or deformation of the plate due to static pressure fluctuations; after forming, the machining center and the hydraulic auxiliary system are closed, in order to cut off the power source and prevent safety risks caused by equipment malfunction during subsequent operations; open the needle-shaped stop valve 12 to completely release the pressure, because if the sealed cavity has residual pressure, the formed part may suddenly deform when the clamp is removed due to pressure release, and releasing the pressure to zero can ensure smooth process when taking out the part; disassemble the upper clamp 4 to take out the formed part, which relies on the structural advantages of the detachable sealed clamp split structure, which is convenient for quick disassembly and can reduce external force interference to the thin-walled formed part during taking out, avoiding damage to the part; the special feature size of the formed part is detected by using the Hexagon IRP40.02 infrared photoelectric probe, which uses its high-precision characteristic of 0.001mm to accurately verify whether the profiles of complex features such as concave, convex and ridge meet the design requirements; the thickness of different areas of the formed part is detected by a double-tip micrometer, which is designed to avoid single-point detection errors and ensure that the thickness of each area after forming still meets the use accuracy.

[0040] Finally, it should be noted that in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the listed element.

[0041] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0042] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and, while certain embodiments according to the principles set forth herein have been shown and described, various modifications and substitutions can be made by those skilled in the art without departing from the spirit and scope of the application as set forth in the following claims. Therefore, the application is not intended to be limited to the embodiments disclosed herein, but rather is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydraulic assisted single point incremental forming apparatus for thin-walled metal parts, characterized by, The detachable sealing clamp is used for clamping the plate to be processed (1), a sealed cavity for containing hydraulic oil is formed between the inside of the detachable sealing clamp and the plate to be processed (1), and the sealed cavity is communicated with a hydraulic auxiliary assembly through a high-pressure hose (13); a cutter (2) for extrusion forming the plate to be processed (1) is arranged at the top of the detachable sealing clamp, the tail end of the cutter (2) is connected with a main shaft of the vertical machining center, the hydraulic auxiliary assembly is electrically connected with a control unit of the vertical machining center, and the control unit is used for linkage control of cutter movement of the vertical machining center and static pressure output of the hydraulic auxiliary assembly.

2. The hydraulic assisted single point incremental forming apparatus for thin-walled metal parts according to claim 1, wherein The detachable sealing clamp is composed of an upper clamp (4) and a lower clamp (5) which are connected in a screw thread manner.

3. The hydraulic assisted single point incremental forming apparatus for thin-walled metal parts according to claim 1, wherein The cutter (2) is in a spherical structure and is made of X210CrW12 high-speed steel, and the axis of the cutter (2) is perpendicular to the upper surface of the plate to be processed (1).

4. The hydraulic assisted single point incremental forming apparatus for thin-walled metal parts according to claim 1, wherein The hydraulic auxiliary assembly comprises a pressure regulating unit communicated with the sealed cavity through the high-pressure hose (13), the pressure regulating unit comprises an oil tank (6) and a leakage-free electromagnetic valve (11), the oil tank (6) and the leakage-free electromagnetic valve (11) are communicated through a first pipeline and a second pipeline, and an air filter (26), a suction filter (25) and an axial plunger pump (8) are sequentially connected in series on the first pipeline along the fluid flow direction, the second pipeline is communicated with an overflow valve (10) and a second gas-liquid accumulator (22) through a third pipeline, and a third pressure gauge (23) is further arranged on the third pipeline. The oil tank (6) is connected with a liquid level and temperature gauge (7), the axial plunger pump (8) is connected with a three-phase asynchronous motor (24), a one-way valve (9) is arranged between the axial plunger pump (8) and the leakage-free electromagnetic valve (11) on the first pipeline, and a needle-shaped stop valve (12) is further communicated between the leakage-free electromagnetic valve (11) and the high-pressure hose (13) through the third pipeline.

5. The hydraulic assisted single point incremental forming apparatus for thin-walled metal parts according to claim 4, wherein The hydraulic auxiliary assembly further comprises a pressure stabilizing unit communicated with the third pipeline through a fourth pipeline, the pressure stabilizing unit comprises an air storage tank (21) and a first gas-liquid accumulator (15), the first gas-liquid accumulator (15) is communicated with the needle-shaped stop valve (12), a precision pressure reducing valve (18) is communicated between the air storage tank (21) and the first gas-liquid accumulator (15), a water separation filter (19) is communicated between the precision pressure reducing valve (18) and the air storage tank (21), the water separation filter (19) and the air storage tank (21) are communicated through a plastic air pipe (20), a right-angle needle valve (16) is arranged on the pipeline between the precision pressure reducing valve (18) and the first gas-liquid accumulator (15), a second pressure gauge (17) is arranged on the precision pressure reducing valve (18), and a first pressure gauge (14) is arranged on the first gas-liquid accumulator (15).

6. A thin-walled metal part hydraulic assisted single point incremental forming method using the thin-walled metal part hydraulic assisted single point incremental forming apparatus as claimed in claim 5, characterized by, The method comprises the following steps: S1: installing the clamp on the machining center, connecting the hydraulic auxiliary assembly, fixing the plate to be processed (1) and setting the cutter, and smearing lubricating oil on the upper surface of the plate; S2: Start the hydraulic auxiliary assembly to raise the pressure in the sealed cavity to 1.5-3 MPa, maintain the pressure for 5-10 s, monitor the pressure and deformation of the plate (1) to be processed during the process, and release the pressure after pre-expanding; S3: Parameter setting and static pressure preparation, generate the spiral machining trajectory, establish a linear relationship between the static pressure P and the machining depth Z and input the control unit, and adjust the static pressure to the preset value; S4: The tool (2) forms layer by layer along the spiral machining trajectory, releases the pressure after forming, and takes out the formed part for detection.

7. The hydraulic assisted single point incremental forming method of thin-walled metal parts according to claim 6, characterized in that, S1: The lower clamp (5) of the detachable sealing clamp is fixed on the workbench of the vertical machining center, the upper clamp (4) is connected with the lower clamp (5) through threads, and the two form a sealed cavity with a rubber sealing groove; the plate (1) to be processed with a thickness of 0.8-1.2 mm is clamped between the upper clamp (4) and the lower clamp (5), and is tightened to ensure that the sealed cavity is leakproof; the relative position of the tool (2) and the plate (1) to be processed is calibrated by the machining center to avoid tool collision during machining, and then metal machining lubricating oil is evenly applied on the upper surface of the plate.

8. The thin-walled metal part hydraulic auxiliary single point incremental forming method according to claim 6, characterized in that, S2: Start the three-phase asynchronous motor (24) to drive the axial plunger pump (8), open the leak-free electromagnetic valve (11) to deliver hydraulic oil (3) to the sealed cavity, and adjust the overflow valve (10) to raise the pressure in the sealed cavity to 1.5-3 MPa; open the second gas-liquid accumulator (22) to absorb the pressure fluctuation of the oil circuit, monitor the pressure in real time through the first pressure gauge (14) during the pressure maintaining period of 5-10 s, and observe the pre-deformation state of the plate (1) to be processed synchronously; after pre-expanding, close the leak-free electromagnetic valve (11) and open the needle-shaped stop valve (12) to release the pressure to zero reading of the first pressure gauge (14).

9. The thin-walled metal part hydraulic auxiliary single point incremental forming method according to claim 6, characterized in that, S3: Generate the spiral machining trajectory of the plate (1) to be processed through the machining trajectory control unit, and set the parameters of the spherical tool (2); based on the deformation requirement of the special-shaped feature of the plate (1) to be processed, establish a linear relationship between the static pressure P and the machining depth Z and input the control unit; start the air storage tank (21), compress the air after purification through the water separation filter (19), adjust the pressure to the preset static pressure value through the precision pressure reducing valve (18), and confirm that the pressure meets the standard through the second pressure gauge (17).

10. The thin-walled metal part hydraulic auxiliary single point incremental forming method according to claim 6, characterized in that, S4: Start the vertical machining center, the tool (2) extrudes and forms the plate (1) to be processed layer by layer along the preset spiral trajectory, the first gas-liquid accumulator (15) continuously provides static pressure support and maintains the pressure during the machining process; after forming, the machining center and the hydraulic auxiliary system are closed, and the needle-shaped stop valve (12) is opened to release the pressure completely; the upper clamp (4) is disassembled to take out the formed part, the special-shaped feature size of the formed part is detected by the Hexagon IRP40.02 infrared photoelectric probe, and the thickness of different areas of the formed part is detected by the double-tip micrometer.

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