Laser cutting device for spindle motor stretching shell production and method thereof

Abstract

The application relates to the field of laser cutting and mechanical processing equipment, in particular to a laser cutting device for main shaft motor stretching shell production and a method thereof; the device comprises a cutting rack, a rotating main shaft, a composite inner support mechanism, a pneumatic control system, a cutting head and an industrial computer; the device adjusts the composite inner support mechanism in combination with the pneumatic control system, so that the flexible mandrel is expanded under the action of positive pressure and is self-adapted to the inner wall of the shell with uneven thickness and curvature change; the core is to follow a negative pressure switching mechanism, so that the variable stiffness medium is converted from a fluid state into a solid-like state with high compression resistance, and then a rigid support conforming to the inner wall is formed; the application discards the traditional outer clamping positioning which is easy to introduce static deformation, solves the transient warping problem caused by processing heating and stress release by using the flexible conformal support with variable pressure and variable stiffness, and effectively improves the cutting seam continuity and size precision.

Description

Technical Field

[0001] This invention relates to the field of laser cutting and machining equipment, specifically to a laser cutting device and method for producing a spindle motor stretch housing. Background Technology

[0002] When the spindle motor is in the production stage of stretching thin-walled shells, laser cutting is often used to trim or open the edges of the deep-drawn parts. Due to the influence of the deep-drawing process, the inner wall of such thin-walled shells generally has physical characteristics such as uneven thickness, continuous local curvature changes, and uneven distribution of internal processing residual stress. To fix such thin-walled shells by laser cutting, existing clamping solutions generally use conventional external clamping positioning mechanisms for clamping and positioning. Although this solution has a certain clamping and fixing capability in conventional processing scenarios, the rigidity of the thin-walled parts is lower than the preset anti-deformation stiffness threshold, and the external clamping force can easily introduce additional static clamping deformation. At the same time, during the laser cutting process of heating and local material peeling, the release of residual stress inside the workpiece will cause transient displacement, and the high-frequency auxiliary airflow ejected by the cutting head will exert an outward pushing effect on the thin-walled cut edge. Relying solely on the traditional external clamping support structure is difficult to effectively suppress the transient warping generated at the cut, causing the cut edge to frequently deviate from the effective working area of ​​the laser focus, resulting in poor cut continuity, dimensional accuracy, and a significant reduction in processing stability.

[0003] Therefore, how to provide adaptive rigid support conforming to the inner wall of the thin-walled shell during laser cutting, effectively suppress residual stress release and transient warping of the cut caused by auxiliary airflow, thereby improving the continuity and dimensional stability of the cut, has become an urgent technical problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a laser cutting device and method for producing a spindle motor stretching housing. Specifically, the technical solution of the present invention is as follows: Laser cutting equipment for producing spindle motor stretch housings includes: Cutting frame; A rotating spindle is correspondingly disposed on the cutting frame, and the center of the rotating spindle passes through a central through hole; A composite internal support mechanism is installed at the front end of the rotating spindle. The composite internal support mechanism includes a flexible mandrel, a variable stiffness medium, and an air passage network that are configured to cooperate. A closed cavity is formed inside the flexible mandrel. The variable stiffness medium is filled in the closed cavity. The air passage network is nested inside the flexible mandrel. The outer surface of the flexible mandrel is machined with a micro-vortex cavity composed of asymmetric inverted sawtooth grooves. A pneumatic control system is matched and installed on the side of the cutting machine frame. The pneumatic control system includes a positive pressure air source, a negative pressure air source and a proportional reversing valve. The tail end of the air pipeline passes through the central through hole and is connected to the common end of the proportional reversing valve. The first input end and the second input end of the proportional reversing valve are respectively connected to the positive pressure air source and the negative pressure air source. A cutting head is positioned above the cutting frame, and a capacitive height adjustment sensor is coaxially mounted at the end of the cutting head. An industrial control computer is connected to control the proportional directional valve and the capacitive height adjustment sensor.

[0005] Furthermore, the micro vortex cavity is defined along the injection direction of the high-pressure auxiliary cutting gas, and its windward slope is gentler than its leeward slope. The leeward surface is vertically arranged, and the depth of the micro vortex cavity is 0.5 mm.

[0006] Furthermore, the variable stiffness medium is composed of polyhedral alumina ceramic particles with a particle size of 50 to 100 μm.

[0007] Furthermore, the composite internal support mechanism also includes a base flange fixed to the front end of the rotating spindle, and the gas pipeline is a stainless steel sintered pipe with micropores on its surface. The blind end of the stainless steel sintered pipe is fixed to the center of the base flange and extends into the variable stiffness medium.

[0008] Furthermore, the cutting head is mounted on a gantry slider located above the cutting machine frame via a linear motor, with the cutting head directly facing the position of the composite inner support mechanism.

[0009] Furthermore, the positive pressure air source provides compressed air at a pressure of 0.2 MPa, the negative pressure air source provides negative pressure with a maximum vacuum of -80 kPa, and the valve core opening of the proportional directional valve is controlled by the analog voltage signal output by the industrial control computer.

[0010] Furthermore, the flexible mandrel body is made of high-temperature resistant polyurethane elastic membrane, and the open end of the flexible mandrel is sealed and pressed against the outer circumference of the base flange by a metal pressure ring.

[0011] A laser cutting control method for producing a spindle motor stretch housing includes: S1. Control the proportional reversing valve to open the positive pressure air source, fill the flexible mandrel with compressed air, put the stretch shell to be cut on the outside of the composite inner support mechanism, and drive the flexible mandrel and the variable stiffness medium to expand outward and fit against the inner wall of the stretch shell. S2. Control the operation of the proportional reversing valve to switch the negative pressure gas source to extract the free gas between the variable stiffness media, so that the variable stiffness media changes from a fluid state to a near-solid state. S3. Control the cutting head to move down to the working height and make it face the position of the composite inner support mechanism. Start the laser beam and spray high-pressure auxiliary cutting gas, so that the high-pressure auxiliary cutting gas is injected into the micro vortex cavity to form a high-speed micro vortex, thereby generating a pneumatic negative pressure directly below the cut. S4. Control the industrial control computer to read the high-frequency capacitance signal of the capacitive height adjustment sensor, and extract the time derivative of the high-frequency capacitance signal as the signal change rate. S5. Control the industrial control computer to determine whether the signal change rate exceeds the preset basic threshold. If so, multiply the signal change rate by the pre-calibrated stiffness conversion coefficient to obtain the critical support stiffness requirement. According to the mechanical calculation model between the stiffness and vacuum degree of the variable stiffness medium, convert the critical support stiffness requirement into a target vacuum degree command. Convert the target vacuum degree command into a control voltage and adjust the valve core opening of the proportional directional valve in real time.

[0012] Furthermore, the industrial control computer runs a support stiffness calculation algorithm; Step S4 includes: The industrial control computer is controlled to use a bandpass filter to extract capacitor signals in the 1000 to 5000 Hz frequency band, and the sampling frequency of the industrial control computer is set to 10 kHz.

[0013] Furthermore, step S5 is followed by: S6. Control the proportional reversing valve to restore the positive pressure air source input, so that the flexible mandrel returns to the fluid state and retracts inward, thereby completing the workpiece unloading and release.

[0014] The present invention has the following beneficial effects: 1. This invention utilizes a composite internal support mechanism consisting of a flexible mandrel, a variable stiffness medium, and an air pipeline network, combined with a pneumatic control system. Under positive pressure, it expands and adaptively conforms to the inner wall of the outer shell, which has uneven thickness and continuously changing curvature, thus avoiding static clamping deformation introduced by external clamping positioning. After switching to negative pressure, the variable stiffness medium transforms from a fluid state to a near-solid state with high compressive stiffness, forming a rigid support conforming to the inner wall. This effectively suppresses transient warping caused by processing heat and residual stress release, improving the continuity of the cut and dimensional accuracy. 2. The flexible mandrel of the present invention has a micro-vortex cavity formed by asymmetric inverted sawtooth grooves on its outer surface. After the high-pressure assisted cutting gas is injected, a high-speed micro-vortex is formed, which generates a pneumatic negative pressure directly below the cut, thus counteracting the outward pushing effect of the airflow on the cut edge of the shell. At the same time, the industrial control computer reads the signal change rate of the capacitive height adjustment sensor and adjusts the valve core opening of the proportional reversing valve in real time in combination with the mechanical calculation model, so as to realize the dynamic adaptive control of the support stiffness, ensuring that the cut edge does not deviate from the laser focus working area and ensuring processing stability. Attached Figure Description

[0015] The following drawings, illustrating embodiments of this application, are incorporated herein by reference and are used to understand this application. The drawings illustrate embodiments of this application and their descriptions, serving to explain the principles of this application. In the drawings, Figure 1 This is a schematic diagram of the overall structure of the device; Figure 2 This is a schematic diagram of the pneumatic control system structure of the device; Figure 3 This is a schematic diagram of the composite internal support mechanism of the device; Figure 4 This is a schematic diagram of the flexible mandrel structure of the device; Figure 5 This is a flowchart of the method of the present invention.

[0016] In the diagram: 1. Cutting frame; 2. Rotary spindle; 3. Central through hole; 4. Composite internal support mechanism; 5. Flexible mandrel; 6. Sealed cavity; 7. Variable stiffness medium; 8. Air pipeline network; 9. Micro-vortex cavity; 10. Pneumatic control system; 11. Positive pressure air source; 12. Negative pressure air source; 13. Proportional directional valve; 14. Cutting head; 15. Capacitive height adjustment sensor; 16. Industrial computer; 17. Polyhedral alumina ceramic particles; 18. Base flange; 19. Stainless steel sintered pipe; 20. Blind end; 21. Gantry slider; 22. Linear motor; 23. High-temperature resistant polyurethane elastic membrane; 24. Metal pressure ring. Detailed Implementation

[0017] In the following description, numerous specific details are set forth to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that embodiments of this application may be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with embodiments of this application.

[0018] Example 1: Laser cutting equipment for producing spindle motor stretch housings includes: like Figure 1 As shown, cutting frame 1; Rotary spindle 2 is correspondingly set on cutting frame 1, with central through hole 3 passing through the center of rotary spindle 2; The composite internal support mechanism 4 is installed at the front end of the rotating spindle 2. The composite internal support mechanism 4 includes a flexible mandrel 5, a variable stiffness medium 7 and an air pipeline network 8 that are configured to cooperate. A closed cavity 6 is formed inside the flexible mandrel 5. The variable stiffness medium 7 is filled in the closed cavity 6. The air pipeline network 8 is nested inside the flexible mandrel 5. The outer surface of the flexible mandrel 5 is machined with a micro vortex cavity 9 composed of asymmetric inverted sawtooth grooves. like Figure 2As shown, the pneumatic control system 10 is matched and installed on the side of the cutting machine frame 1. The pneumatic control system 10 includes a positive pressure air source 11, a negative pressure air source 12 and a proportional reversing valve 13. The tail end of the air pipeline network 8 passes through the central through hole 3 and is connected to the common end of the proportional reversing valve 13. The first input end and the second input end of the proportional reversing valve 13 are respectively connected to the positive pressure air source 11 and the negative pressure air source 12. A cutting head 14 is positioned above the cutting frame 1, and a capacitive height adjustment sensor 15 is coaxially mounted at the end of the cutting head 14. The industrial computer 16 is connected to control the proportional directional valve 13 and the capacitive height adjustment sensor 15. Laser cutting equipment for spindle motor stretching housing production is used to cut thin-walled housings after deep stretching. The inner wall of such housings has problems such as uneven thickness, continuous local curvature changes and uneven residual stress distribution. Conventional external clamping positioning is prone to static deformation when clamping, and relying solely on external support is difficult to suppress transient warping at the cut. Therefore, the cutting frame 1 serves as the mounting base for the entire machine. It adopts a welded frame combined with a machined mounting surface after aging treatment to provide mounting and positioning for the rotary spindle 2, the cutting head 14, and the pneumatic control system 10. The rotary spindle 2 is set inside the spindle box of the cutting frame 1. The central through hole 3 of the rotary spindle 2 is used to introduce air and enable the composite internal support mechanism 4 to continuously obtain positive or negative pressure in the rotating state. The composite internal support mechanism 4 is installed at the front end of the rotating spindle 2. Its core is the cooperation of the flexible mandrel 5, the variable stiffness medium 7 and the air pipeline network 8. The flexible mandrel 5 is a closed covering that can undergo radial elastic deformation, forming a sealed cavity 6 inside, and the variable stiffness medium 7 is filled in the sealed cavity 6. The phase change here is not a temperature phase change, but refers to the transformation of the particulate medium from a flowable accumulation state to a solid-like support state that reaches the predetermined compressive stiffness threshold under pressure conditions. The gas pipeline network 8 is nested inside the flexible mandrel 5. It is used to supply gas to the sealed cavity 6 during the positive pressure stage to make the flexible mandrel 5 expand and fit against the inner wall of the workpiece. During the negative pressure stage, it extracts the free gas between particles to cause particle blockage in the variable stiffness medium 7. The outer surface of the flexible mandrel 5 is provided with asymmetric inverted sawtooth grooves to form a micro vortex cavity 9. The purpose is to use the auxiliary gas ejected from the cutting head 14 to induce a local low-pressure area below the cut, thereby reducing the normal outward thrust of the cutting airflow on the edge of the thin-walled cut. The common end of the proportional directional valve 13 in the pneumatic control system 10 is connected to the tail end of the air pipeline network 8. The first input end is connected to the positive pressure air source 11, and the second input end is connected to the negative pressure air source 12. The industrial control computer 16 outputs control quantities according to the process stage and sensor signals to realize positive and negative pressure switching and negative pressure adjustment. The cutting head 14 is located above the cutting frame 1 and is used to emit a laser beam and coaxially output auxiliary cutting gas. The capacitive height sensor 15, which is coaxially mounted at the end, is used to continuously detect the capacitance change between the nozzle and the surface of the housing. The industrial control computer 16 is simultaneously connected to the proportional directional valve 13 and the capacitive height adjustment sensor 15, receiving high-frequency capacitive signals and outputting valve control voltage. Through the above structural combination, the equipment exhibits high compliance during the workpiece clamping stage, forms an internal rigid support consistent with the shape of the inner wall during the cutting stage, and combines the pneumatic anti-warping effect of the micro vortex cavity 9 and the variable stiffness control driven by the capacitive signal to reduce the probability of the kerf edge leaving the focal working area, thereby improving the continuity and dimensional stability of the kerf.

[0019] The micro vortex cavity 9 is defined along the injection direction of the high-pressure auxiliary cutting gas. Its windward slope is gentler than the leeward slope, and the leeward side is set vertically. The depth of the micro vortex cavity 9 is 0.5mm. The micro vortex cavity 9 is disposed on the outer surface of the flexible mandrel 5 and is repeatedly arranged at predetermined intervals along the circumferential and axial directions of the flexible mandrel 5; the windward side of the micro vortex cavity 9 is the inclined surface that the auxiliary cutting gas jet contacts when it enters the groove, and the leeward side is the other side wall opposite to the jet direction. The slope of the windward side is gentler than that of the leeward side, so that when the airflow enters the ditch, it can be guided to the bottom of the ditch along the gentle slope. The leeward side is set vertically so that when the airflow reaches the rear of the ditch, the flow separation occurs to the expected degree, forming a microscale vortex structure with predetermined stability in the local area. This structure differs from ordinary rectangular grooves or symmetrical triangular grooves. Its purpose is not simply to increase surface roughness, but to create a local pressure drop zone corresponding to high-speed eddies directly below the cut. The groove depth is set to 0.5mm, which is a value determined by comprehensively considering the commonly used cutting auxiliary gas pressure, nozzle-to-workpiece distance, and surface elastic deformation of the flexible mandrel 5 for thin-walled stretch shells. When the depth is less than 0.3 mm, the groove volume is insufficient, the local flow separation does not achieve the expected effect, and the negative pressure amplitude is lower than the set threshold; when the depth is greater than 0.8 mm, the effective support area of ​​the flexible mandrel 5 surface decreases, and the surface contact uniformity with the inner wall decreases under the negative pressure locking state. When 0.5mm is selected, there is a relatively stable velocity gradient between the micro vortex formed by the airflow in the groove and the mainstream near the top edge of the groove. When the high-pressure auxiliary gas is ejected from the cutting head 14, an adsorption effect opposite to the outer top trend is generated directly below the cut. For those skilled in the art, the windward slope can be selected from 20° to 45°, and the leeward slope can be selected from 85° to 90°, both of which fall within the scope of the defined technical concept; after adopting this geometric relationship, the amount of kerf edge lifting caused by the auxiliary gas during the cutting process can be reduced, and the kerf width fluctuation will decrease accordingly.

[0020] The variable stiffness medium 7 is composed of polyhedral alumina ceramic particles 17, the particle size of which is 50 to 100 μm. The variable stiffness medium 7 is filled in the sealed cavity 6 of the flexible mandrel 5 to change the overall support stiffness under different pressure conditions; the polyhedral alumina ceramic particles 17 refer to particles with multiple edges and irregular contact surfaces. Compared with spherical particles, this morphology can generate higher mechanical interlocking and contact friction between particles after vacuuming, thus making it more conducive to the establishment of particle blockage effect. Alumina ceramic materials possess the hardness, heat resistance, and high-temperature softening resistance required by the laser cutting environment, making them suitable for placement near the laser cutting area. The particle size is set to 50 to 100 μm because this range balances flowability and locking stiffness. When the particle size is less than 50 μm, the specific surface area of ​​the particles increases significantly, the resistance to gas discharge between particles increases, the negative pressure establishment time is prolonged, and fine particles are prone to local agglomeration during long-term cycling; when the particle size is greater than 100 μm, the ability of the flexible mandrel 5 to replicate the fine contour of the inner wall of the workpiece decreases during the positive pressure expansion stage, and discrete peaks are easily observed in the local contact pressure distribution. After using 50 to 100 μm polyhedral alumina ceramic particles 17, the particle group can rearrange with the deformation of the flexible mandrel 5 when positive pressure is input, forming a surface contact that adapts to the inner wall of the stretched shell; when negative pressure is input, the free gas between the particles is extracted, the normal contact force of the particles is increased, and the overall elastic modulus increases. For the same vacuum level, the support stiffness formed by polyhedral alumina ceramic particles 17 is higher than that of spherical glass microspheres, which can reduce the transient displacement caused by the release of residual stress in the cut area; alumina ceramic particles with a purity of not less than 92% by mass can also be used to ensure its wear resistance.

[0021] like Figure 3 As shown, the composite internal support mechanism 4 also includes a base flange 18 fixed to the front end of the rotating spindle 2, and the gas pipeline network 8 is a stainless steel sintered pipe 19 with micropores on its surface. The blind end 20 of the stainless steel sintered pipe 19 is fixed to the center of the base flange 18 and extends into the variable stiffness medium 7. In addition to the flexible mandrel 5, the variable stiffness medium 7, and the air pipeline network 8, the composite internal support mechanism 4 also includes a base flange 18. The base flange 18 is used to achieve a rigid connection between the composite internal support mechanism 4 and the front end of the rotating spindle 2, and to provide an installation base for the sealing and fixing of the flexible mandrel 5, air pipeline introduction, and axial positioning. The base flange 18 can be made of stainless steel or aluminum alloy into a disc-shaped structure, with a gas guide channel in the center, which is connected to the central through hole 3 of the rotating spindle 2. The gas pipeline network 8 adopts a stainless steel sintered tube 19 with micropores on its surface. The blind end 20 of the stainless steel sintered tube 19 is fixed to the center of the base flange 18 and extends into the variable stiffness medium 7. The blind end 20 refers to the end that is closed away from the external gas supply interface. The gas is dispersed in the axial and circumferential directions into the particle accumulation or extracted from the particle accumulation through the micropores on the sintered tube wall. The reason for using a microporous sintered tube instead of a single-opening straight tube is that a single-opening air supply and exhaust will cause the pressure to change rapidly near the opening end and slowly at the far end, resulting in inconsistent expansion and locking states of the flexible mandrel 5 along the axial direction. The sintered tube can improve the uniformity of the pressure field through multi-point distributed air exchange, enabling the variable stiffness medium 7 to simultaneously complete positive pressure conformation and negative pressure locking within the sealed cavity 6. The sintered tube is made of stainless steel, which can ensure that the structural strength is maintained under cyclic negative pressure, particle friction and cutting heat environment; the micropore size can be selected from 1 to 20μm, which allows air to pass through while preventing particles from entering the tube and causing blockage. After the base flange 18 is connected to the rotating spindle 2, the sintering tube extends into the flexible mandrel 5 along the spindle axis, shortening the gas supply path and making the gas transmission flow resistance lower than the preset resistance threshold, which is suitable for achieving rapid switching under the control of the proportional reversing valve 13. This structure helps to control the negative pressure build-up time within the allowable range of the cutting cycle and reduce the stiffness difference in different areas of the composite inner support mechanism 4.

[0022] The cutting head 14 is mounted on the gantry slider 21 above the cutting machine frame 1 via a linear motor 22, and the cutting head 14 is directly facing the location of the composite inner support mechanism 4. The cutting head 14 is mounted on the gantry slider 21 above the cutting machine frame 1 via a linear motor 22. The gantry spans above the rotating spindle 2 and the composite inner support mechanism 4. The linear motor 22 is used to drive the cutting head 14 to make linear displacement along a set direction. Its advantage is that the transmission chain is shortened and it has a low backlash that meets the preset processing accuracy tolerance, making it suitable for performing tracking tasks that are sensitive to nozzle gap in laser cutting of thin-walled parts. The cutting head 14 is positioned directly opposite the composite inner support mechanism 4, so that the detection axes of the laser beam, the auxiliary cutting gas jet, and the capacitive height adjustment sensor 15 correspond to the local cutting area of ​​the supported workpiece. For cylindrical or near-cylindrical stretched shells, the rotating spindle 2 drives the workpiece to rotate, and the cutting head 14 performs axial feeding or radial positioning on the gantry to form a predetermined cutting trajectory; the stroke of the linear motor 22 can be set from 100 to 600 mm according to the shell length, and the repeatability can be controlled within 0.02 mm to ensure that the cutting head 14 always covers the effective support area of ​​the composite inner support mechanism 4; The spatial correspondence between the cutting head 14 and the composite inner support mechanism 4 has direct technical significance: only when there is a composite inner support mechanism 4 in a negative pressure locked state below the cutting area, and the micro vortex cavity 9 is located in the main impact area of ​​the auxiliary gas, can the inner support stiffness and the aerodynamic negative pressure effect be exerted simultaneously; if the cutting head 14 deviates from the position of the composite inner support mechanism 4, there will be no effective support below the cutting surface, which will cause the thin-walled shell to have a normal offset exceeding the preset processing tolerance after local heating; By combining a gantry frame with a linear motor 22, the cutting head 14 can maintain its adaptability to workpieces of different positions and lengths without changing the installation method of the composite internal support mechanism 4. Compared with the traditional rotary servo motor and ball screw transmission mechanism, the linear motor 22 eliminates the intermediate mechanical conversion link. In response tests for high-frequency micro-displacement, the traditional ball screw mechanism is limited by backlash and mechanical elastic deformation, and its dynamic following error is usually above 0.05mm. However, the cutting head 14 using the linear motor 22 has a lag time between the actual motion trajectory and the command trajectory that is reduced by at least 60%, and the dynamic following error is effectively controlled within 0.01mm. Positive pressure air source 11 provides compressed air at a pressure of 0.2MPa, negative pressure air source 12 provides negative pressure with a maximum vacuum of -80kPa, and the valve core opening of proportional directional valve 13 is controlled by the analog voltage signal output by industrial control computer 16. The positive pressure air source 11 is used to drive the expansion of the flexible mandrel 5 and redistribute the variable stiffness medium 7 within the sealed cavity 6. Compressed air with a pressure of 0.2 MPa is selected. This pressure level is sufficient to cause the high-temperature resistant polymer flexible mandrel 5 to expand radially and conform to the inner wall of the spindle motor tension housing, while preventing the thin-walled workpiece from undergoing pre-deformation from the inside out due to excessive pressure. In practical applications, the positive pressure air source 11 can be provided by an air compressor in conjunction with a pressure reducing valve and an air tank. The stability of the air supply pressure should be controlled within ±0.01 MPa. The negative pressure gas source 12 provides a maximum vacuum of -80 kPa to extract free gas between particles of the variable stiffness medium 7 and establish particle blockage. When the vacuum is below -40 kPa, the normal compressive effect between particles is limited, and the overall stiffness is not improved enough. When the vacuum reaches the range of -60 kPa to -80 kPa, the compressive deformation of the particle group inside the flexible mandrel 5 decreases significantly. The valve core opening of the proportional directional valve 13 is controlled by the analog voltage signal output by the industrial computer 16. The analog voltage can be 0 to 10V or 4 to 20mA. The corresponding voltage signal is output through the conversion module, and the proportional directional valve 13 adjusts the degree of connection between the common terminal and the negative pressure air source 12 or the positive pressure air source 11 accordingly. The use of a proportional directional valve 13 instead of a regular two-position valve is intended to make the negative pressure continuously adjustable, facilitating real-time changes in support stiffness based on feedback signals from the capacitive height sensor 15. When the industrial control computer 16 outputs the first preset range voltage, the proportional directional valve 13 maintains the basic vacuum level, reducing media wear and energy consumption. When the industrial control computer 16 outputs the second preset range voltage, the proportional directional valve 13 increases the connection cross-section with the negative pressure gas source 12, improving the pumping speed and target vacuum level. With this parameter configuration, the equipment can not only complete the flexible bonding during the feeding stage, but also change the internal support strength according to the degree of local stress release during the cutting process. To facilitate implementation, a valve control calibration relationship is pre-established between the industrial control computer 16 and the proportional directional valve 13. During calibration, a vacuum sensor is connected to the common terminal, and the control voltage is output step by step at intervals of 0.5V or 1V. The stable vacuum degree after the valve and the time required to reach stability are recorded, thereby forming a one-to-one correspondence table between the control voltage, valve core opening degree and actual vacuum degree. This correspondence table is used as a reference during control, rather than relying on subjective human estimation; preferably, the 0 to 10V control range can be divided into three logic segments: 0.2V as a positive pressure conduction or pressure relief transition segment, 2 to 4V as a basic locking segment, maintaining a vacuum of -40 to -50kPa; 4 to 7V as an enhanced support segment, maintaining a vacuum of -50 to -70kPa; and 7 to 10V as a high-rigidity anti-warping segment, maintaining a vacuum of -70 to -80kPa. With this setting, when the industrial computer 16 receives a control request from the upper level, it first determines the required vacuum range, then calls the corresponding table to output the corresponding voltage, so that the proportional directional valve 13 is stabilized at the corresponding opening. If the deviation between the vacuum sensor feedback value and the target value exceeds 5000Pa and lasts for more than two sampling cycles, the industrial computer 16 will then fine-tune the output voltage according to the predetermined step size until the feedback value returns to the allowable deviation range. Therefore, the analog voltage not only has driving significance, but also corresponds to a clear support state level in the control logic, which can provide a repeatable execution basis for subsequent adjustment of vacuum degree based on capacitor signal.

[0023] like Figure 4 As shown, the main body of the flexible mandrel 5 is made of high-temperature resistant polyurethane elastic membrane 23, and the open end of the flexible mandrel 5 is sealed and pressed against the outer circumference of the base flange 18 by a metal pressure ring 24. The flexible mandrel 5 is made of high-temperature resistant polyurethane elastic film 23, which aims to balance elastic recovery, wear resistance, resistance to cutting heat radiation and air tightness. The high-temperature resistant polyurethane elastic film 23 can be selected from film materials with a Shore hardness of 70 to 95 and a thickness of 0.5 mm to 2 mm. When the thickness is less than 0.5 mm, the durability decreases after long-term exposure to particle friction and alternating internal pressure; when the thickness is greater than 2 mm, the positive pressure required for expansion bonding increases, and the forming accuracy of the micro vortex cavity 9 decreases; the open end of the flexible mandrel 5 is sealed and pressed against the outer circumference of the base flange 18 by a metal pressure ring 24. The metal pressure ring 24 can adopt an open or segmented structure, and the edge of the elastic membrane is pressed against the flange sealing step by evenly distributed bolts to form a reliable circumferential seal; The reason for using mechanical clamping instead of adhesive fixing is that the composite inner support mechanism 4 needs to withstand repeated positive and negative pressure switching. The adhesive layer is prone to aging when it is under tension and heat for a long time. The metal pressure ring 24 clamping method is easy to disassemble and maintain and has high sealing stability. When the high-temperature resistant polyurethane elastic membrane 23 expands radially during the positive pressure stage, it can drive the internal polyhedral alumina ceramic particles 17 to rearrange along the inner wall contour of the workpiece, thereby obtaining a high geometric replication capability; during the negative pressure stage, the elastic membrane, as the outer coating interface, transmits the overall stiffness formed by particle blockage to the inner wall of the workpiece. The reliable seal at the open end also prevents outside air from leaking into the sealed cavity 6 from the end, avoiding a drop in local vacuum that could affect the solid-like support effect; after the material and connection form are combined, the composite inner support mechanism 4 can maintain a relatively stable expansion amount and locking stiffness during multiple cutting cycles.

[0024] Example 2: like Figure 5 As shown, the laser cutting control method for producing a spindle motor stretch housing includes: S1. Control the proportional reversing valve 13 to work and turn on the positive pressure air source 11 to fill the flexible mandrel 5 with compressed air, and put the stretch shell to be cut on the outside of the composite inner support mechanism 4, driving the flexible mandrel 5 and the variable stiffness medium 7 to expand outward and fit against the inner wall of the stretch shell. S2. Control the proportional reversing valve 13 to switch the negative pressure gas source 12 to extract the free gas between the variable stiffness media 7, so that the variable stiffness media 7 changes from a fluid state to a near-solid state. S3. Control the cutting head 14 to move down to the working height and make it face the position of the composite inner support mechanism 4. Start the laser beam and spray high-pressure auxiliary cutting gas, so that the high-pressure auxiliary cutting gas is injected into the micro vortex cavity 9 to form a high-speed micro vortex, thereby generating a pneumatic negative pressure directly below the cut. S4. Control the industrial computer 16 to read the high-frequency capacitance signal of the capacitive height adjustment sensor 15 and extract the time derivative of the high-frequency capacitance signal as the signal change rate. S5. Control the industrial control computer 16 to determine whether the signal change rate exceeds the preset basic threshold. If so, multiply the signal change rate by the pre-calibrated stiffness conversion coefficient to obtain the critical support stiffness requirement. According to the mechanical calculation model between the stiffness and vacuum degree of the variable stiffness medium 7, convert the critical support stiffness requirement into a target vacuum degree command, convert the target vacuum degree command into a control voltage, and adjust the valve core opening of the proportional reversing valve 13 in real time. This control method is used to drive the equipment to complete the adaptive support cutting of the thin-walled stretched shell; In S1, the spindle motor stretching housing to be cut is fitted outside the composite inner support mechanism 4. The industrial control computer 16 outputs a control signal to the proportional reversing valve 13 to conduct the positive pressure air source 11. 0.2MPa compressed air enters the flexible mandrel 5 through the central through hole 3 of the rotating spindle 2 and the air pipeline network 8. The flexible mandrel 5 and the variable stiffness medium 7 expand outward together. Since the particulate medium can flow relative to each other under positive pressure, the outer surface of the flexible mandrel 5 gradually adheres to the inner wall of the stretching housing, forming an initial positioning with lower clamping stress. In S2, the industrial control computer 16 controls the proportional directional valve 13 to switch the negative pressure gas source 12 to extract free gas between the variable stiffness media 7; here, fluid state refers to the loose state in which the particle group can rearrange under low inter-particle constraints, and solid-like state refers to the state in which the particle blockage forms and the whole exhibits high compressive stiffness but is not truly melted and solidified; as the vacuum degree increases, the inter-particle friction increases, and the composite internal support mechanism 4 establishes a conformal rigid support between the workpiece inner wall; In S3, the cutting head 14 moves down to the set working height under the drive of the linear motor 22, and the laser beam begins to cut. High-pressure auxiliary cutting gas is ejected synchronously. After the jet enters the micro vortex cavity 9 on the outer surface of the flexible mandrel 5, it is guided by the asymmetric groove to form a high-speed micro vortex, generating a local aerodynamic negative pressure directly below the cut. This negative pressure acts on the inner side of the cut edge, which can reduce the tendency of the edge to turn outward caused by the main jet of auxiliary gas. In S4, the industrial computer 16 reads the high-frequency capacitance signal from the capacitive height adjustment sensor 15. The capacitive height adjustment sensor 15 detects the signal fluctuation caused by the change in capacitance between the nozzle and the cut surface as the gap changes. The industrial computer 16 performs discrete sampling on the high-frequency capacitance signal and calculates the time derivative to obtain the signal change rate. The larger the signal change rate, the higher the amplitude and frequency of the small change in the gap between the nozzle and the workpiece per unit time, and the larger the normal deformation displacement of the warped cut area. Entering S5, the industrial control computer 16 converts the signal change rate into the current critical support stiffness requirement based on the pre-calibrated stiffness conversion coefficient. This coefficient can be obtained through standard sample test cutting calibration, that is, recording the correspondence between the capacitance signal change rate and the cut warpage under a known vacuum degree, and then calculating the support stiffness required to suppress a specific warpage. Based on the mechanical calculation model between the stiffness and vacuum degree of the variable stiffness medium 7, the critical support stiffness requirement is converted into the target vacuum degree command. This mechanical model can be implemented by a piecewise linear model or a lookup table model, as long as the required stiffness can be mapped to the output requirements of the negative pressure gas source 12. The industrial control computer 16 then converts the target vacuum degree command into an analog control voltage and adjusts the valve core opening of the proportional directional valve 13 in real time to match the negative pressure magnitude with the degree of local stress release. Through this method, the support stiffness is no longer fixed, but is adjusted according to the cutting position and the transient deformation characteristics of the workpiece, thereby reducing the kerf offset and the probability of incomplete cutting. To ensure the executable nature of the control logic in S4 and S5, the meanings and sources of the signal change rate, stiffness conversion coefficient, critical support stiffness requirement, and target vacuum degree command in the system are further defined as follows: The signal change rate is a quantitative indicator of how fast the capacitance signal changes per unit time, used to characterize the severity of gap disturbances near the cut; the critical support stiffness requirement is the minimum internal support stiffness required to limit the current disturbance within the allowable cutting deviation. The stiffness conversion coefficient is a calibration coefficient that converts the change in electrical signal on the sensor side into the stiffness requirement on the support side. In essence, it reflects the correspondence between gap pulsation and the stiffness required for anti-warping under specific equipment, specific nozzle gap and specific workpiece material conditions. The target vacuum degree command is an intermediate control quantity sent by the industrial control computer 16 to the pneumatic control system 10, which represents the negative pressure level that should be established to achieve the critical support stiffness requirement. The stiffness conversion factor is not an abstract constant, but is determined during the trial cutting calibration stage: first, a standard shell with the same wall thickness, material and curvature as the actual workpiece is selected, and trial cutting is carried out at multiple vacuum levels of -40, -50, -60, -70 and -80 kPa respectively; Record the statistical value of the signal change rate after bandpass processing, the corresponding cut warpage amount, and whether it exceeds the focal working area at each vacuum level; then, from the vacuum level group that meets the cut continuity requirements, reversely select the minimum vacuum level required to suppress the pulsation level, and record the equivalent support state corresponding to the minimum vacuum level as the critical support stiffness requirement at the pulsation level. This allows the establishment of a calibration table from the rate of change of the signal to the critical support stiffness requirement. The stiffness conversion coefficient can be understood as the slope or scaling factor of the calibration table in adjacent intervals. Preferably, the industrial control computer 16 does not directly provide the final control voltage all at once, but executes the following sequence: reads the signal change rate within the current sampling window; finds its range in the calibration table; if the signal change rate is lower than the basic threshold, maintains the basic vacuum level. If it is in the middle range, the corresponding enhanced support level is called; if it is higher than the alarm threshold, the high stiffness anti-warping level is called directly; the critical support stiffness requirement is sent to the stiffness-vacuum degree correspondence table to obtain the target vacuum degree command; according to the preset voltage-vacuum degree correspondence table, the matching control voltage is output to the proportional reversing valve 13. Both the basic threshold and the alarm threshold mentioned above can be obtained by cutting a standard sample. The basic threshold represents the maximum allowable rate of signal change that the cut can still be stably kept within the focal working area, while the alarm threshold represents the rate of signal change that the probability of cut deviation will increase significantly if the vacuum level is not increased in time. To avoid frequent valve core movement due to transient noise, the industrial computer 16 preferably performs vacuum level switching only when the same threshold is exceeded in two or three consecutive sampling windows; after the signal change rate falls back to a lower range and remains there for a predetermined time, the vacuum level is gradually reduced. Through this process of step-by-step judgment, table lookup and conversion, and hierarchical execution, each parameter in S5 is configured as a process variable with an independent signal input source, judgment algorithm logic, and control signal output terminal. A mechanical calculation model is established to correlate the stiffness of the variable stiffness medium 7 with the vacuum level. The purpose is to convert the critical support stiffness requirement calculated by the industrial control computer 16 into a target vacuum level command that can be executed by the proportional directional valve 13, when the equivalent support stiffness inside the flexible mandrel 5 cannot be directly measured online. This model logically comprises three consecutive components: The first step receives the current variable stiffness medium type 7, particle size range, and effective support area of ​​flexible mandrel 5 as fixed process parameters to determine the stiffness level boundary of the current equipment. The second stage receives the critical support stiffness requirement and looks up the lowest vacuum level that meets the stiffness requirement in a pre-calibrated stiffness-vacuum degree correspondence table. The third step outputs the lowest vacuum level as the target vacuum level command to the voltage-vacuum level correspondence table, and then the industrial control computer 16 generates the valve control voltage; specifically, the underlying calculation rules of the mechanical calculation model can be expressed by the following empirical formula: in, The equivalent support stiffness of the composite internal support mechanism 4. This represents the initial particle packing stiffness when the vacuum level is 0. The stiffness enhancement coefficient is related to the material, particle size, and thickness of the flexible mandrel 5 of the variable stiffness medium 7, and its dimensions are: Used to balance the dimensions on both sides of an equation. The current vacuum level, It is the absolute value symbol. The nonlinear compaction index is typically set to 0.5 to 0.6 for polyhedral alumina ceramic particles 17. Using this formula, given the material parameters, the industrial control computer 16 can inversely solve for the corresponding target vacuum degree command after obtaining the critical support stiffness requirement: In practical applications, in order to balance the accuracy of the mechanical model with the real-time operation of the industrial site, the industrial control computer 16 calculates the discrete stiffness nodes in advance based on the above-mentioned underlying formula, thereby generating the aforementioned stiffness-vacuum degree correspondence table. During online control, the target vacuum degree command can be quickly obtained by directly looking up the table and supplementing it with linear interpolation. The physical relationship represented by the model is as follows: when the negative pressure increases, the free gas between the particles of the variable stiffness medium 7 decreases, and the external atmospheric pressure exerts a higher compressive force on the particle stack through the flexible mandrel 5, which enhances the friction and mechanical interlocking between particles. Therefore, the composite internal support mechanism 4 exhibits improved resistance to compressive deformation. When the negative pressure decreases or air is reintroduced, the constraint between particles weakens and the support stiffness decreases. Positive correlation does not require stiffness and vacuum degree to maintain strict linearity across the entire range. Rather, it means that within the allowable operating range of -40kPa to -80kPa of this equipment, the equivalent support stiffness level that can be obtained by increasing the vacuum degree level does not decrease. After adopting this model, a clear data flow and causal relationship are formed between the disturbance judgment on the capacitor signal side, the support stiffness requirement on the particulate medium side, and the target vacuum degree on the pneumatic actuator side. To further clarify the data flow and business logic of the above algorithm, the following is an explanation using a specific quantitative deduction example: Assume that the signal change rate calculated within the current sampling window is 0.5pF / m, and the pre-calibrated stiffness conversion coefficient is 200N / mm stiffness requirement per picofarad per millisecond; The industrial computer 16 multiplies the two to obtain the critical support stiffness requirement of 100 N / mm; the industrial computer 16 then inputs this value into the stiffness-vacuum degree correspondence table for comparison; if the table shows that the basic vacuum degree required to maintain 100 N / mm stiffness is -60 kPa, then the target vacuum degree command is -60 kPa. The industrial control computer 16 calls the voltage-vacuum degree correspondence table. If the control voltage corresponding to -60kPa is 6V, the industrial control computer 16 will finally output a 6V analog voltage to the proportional directional valve 13 through the digital-to-analog conversion interface. The control logic can be implemented by programming through the above-mentioned preset logic operation rules and data mapping relationship.

[0025] The industrial computer 16 runs a support stiffness calculation algorithm; step S4 includes: controlling the industrial computer 16 to use a bandpass filter to extract the capacitor signal in the 1000 to 5000 Hz frequency band, and setting the sampling frequency of the industrial computer 16 to 10 kHz. The industrial computer 16 runs a support stiffness calculation algorithm; the input of the algorithm is the original capacitance signal sequence collected by the capacitive height adjustment sensor 15, and the output is the support stiffness requirement corresponding to the current micro warping trend. The sampling frequency of the industrial computer 16 is set to 10kHz. The reason is that when cutting a thin-walled stretch shell, the micro-vibration of the nozzle gap caused by residual stress release, heat input fluctuation and airflow disturbance is mainly concentrated in the frequency band higher than the macroscopic profile change. 10kHz sampling can meet the Nyquist sampling requirements of the 1000 to 5000Hz frequency band. In S4, the industrial computer 16 uses a bandpass filter to extract the 1000 to 5000 Hz frequency band components of the original capacitor signal. The purpose is to suppress the low-frequency components caused by the macro-roundness error of the workpiece, the spindle rotation deviation and the low-frequency follow-up of the cutting head 14, while filtering out random noise higher than the main frequency band of the system's mechanical response. The bandpass filter can be a digital finite impulse response filter or a digital infinite impulse response filter; for the finite impulse response filter, the filter order can be set from 32 to 128 according to the processor's computing power; after obtaining the capacitance signal in the 1000 to 5000 Hz frequency band, the industrial control computer 16 calculates the difference between adjacent sampling points and divides it by the sampling time interval to obtain an approximate value of the time derivative, i.e., the signal rate of change sequence; The mapping algorithm can further calculate the root mean square value, peak value, or envelope value within the sliding window of the signal change rate and correspond it to the pre-established stiffness requirement table. The technical significance of this mapping algorithm is that it extends the signal originally used by the capacitive sensor for height control to characterize the microscale thermal deformation trend, so that the same sensor can simultaneously perform the functions of gap monitoring and support adjustment triggering, reducing additional detection hardware. After adopting the 1000 to 5000 Hz frequency band, the industrial control computer has a high sensitivity to identify millisecond-level warping precursors near the cut, which can improve the vacuum degree of the composite inner support mechanism 4 before macroscopic morphological changes cause significant deviations; the preferred algorithm for calculating support stiffness includes the following processing steps in sequence: The first step is to acquire the original capacitance signal and write it into a sliding window with a length of 50 to 200 sampling points at a fixed sampling period; The second step is to perform baseline removal on the original signal within the window to eliminate the DC component caused by the nozzle static height and slow profile changes. The third step is to perform a 1000 to 5000 Hz bandpass filter on the baseline-removed signal to obtain a frequency band signal that only reflects micro-vibrations and transient warping precursors. The fourth step is to perform adjacent-point difference analysis on the bandpass signal to obtain the signal rate of change sequence. The specific calculation rule is as follows: Let the sampled sequence of the capacitor signal after bandpass filtering be... Then the first The signal change rate value corresponding to each sampling point The calculation formula is: in, This is the current sampling point number. This is the sampled value of the capacitance signal after bandpass filtering at the current sampling point. This is the sampled value of the capacitance signal after bandpass filtering from the previous sampling point. The sampling time interval; The fifth step is to calculate the root mean square value or peak value of the sequence within the current window, forming a single signal fluctuation characteristic value. Specifically, this is calculated using a length of... The root mean square value is calculated using a sliding window as a characteristic value of signal fluctuation. Its formula is: in, For summation, The square root symbol is used. This is the current sampling point number. This is the index number of the sampling point offset in the sliding window. This represents the total number of sampling points within the sliding window. For the first The signal change rate value corresponding to each sampling point; through the aforementioned clearly defined differential and statistical calculation rules, the industrial control computer 16 can reliably convert the high-frequency and alternating positive and negative original capacitance disturbance into a monotonically positive characteristic quantity that reflects the vibration intensity. ; Step 6, this feature quantity Compare with a preset level threshold and output one of the stiffness requirement levels: basic support, reinforced support, or high-stiffness support. The seventh step is to call the stiffness-vacuum degree correspondence table and the voltage-vacuum degree correspondence table based on the stiffness requirement level to generate the final valve control voltage. Thus, the input, processing, output, and flow direction of the algorithm are all clear: the input is the original capacitance sampling sequence, the intermediate quantities processed are the bandpass signal, the signal change rate sequence, and the window feature quantity, and the output is the support stiffness requirement level, which is further flowed to the proportional directional valve 13 control module. The level threshold in the mapping algorithm is obtained through calibration. During calibration, the frequency band features of multiple windows are collected under known stable cutting state, slight warping state and obvious warping state respectively. The boundary point of the three types of sample distribution is taken as the first threshold and the second threshold. The first threshold corresponds to the boundary where stable cutting transitions to the point where enhanced support is required, and the second threshold corresponds to the boundary where high stiffness anti-warping control needs to be entered immediately. To prevent misjudgment of a single abnormal point, the industrial control computer 16 preferably updates the stiffness requirement level only when the judgments of two consecutive windows are consistent. If the results of the two windows are inconsistent, the level of the previous control cycle remains unchanged. After adopting this process, the mapping algorithm constitutes an implementable processing chain consisting of sampling, filtering, differencing, feature extraction, thresholding, and execution output. In terms of software implementation details, the data flow format and judgment criteria of the above mapping algorithm are as follows: The industrial computer 16 uses a single-precision floating-point array to store the sampled data in the sliding window, and the bandpass filtering and differential operation are completed in a pipeline manner in the memory buffer; The signal fluctuation feature values ​​extracted here and the various threshold values ​​set are all physically equivalent to picofarads per millisecond; assuming the first threshold obtained by calibration is 0.3 and the second threshold is 0.8; When the calculated signal fluctuation characteristic value is 0.2, which is below the first threshold, the industrial control computer 16 determines that the cutting is stable and outputs the basic support level; when the characteristic value rises to 0.5, which is between the two thresholds, the industrial control computer 16 determines that there is slight warping and outputs the enhanced support level; when the characteristic value reaches 0.9, which is above the second threshold, the industrial control computer 16 immediately outputs the high stiffness support level. Under the same cutting process parameters, when the mapping algorithm is turned off, the root mean square error of the kerf width fluctuation is 0.05mm; after turning on the mapping algorithm and performing real-time stiffness adjustment, the root mean square error of the kerf width fluctuation is reduced to 0.01mm, and the probability of the kerf edge leaving the focal working area is reduced by more than 80%, which effectively improves the continuity and dimensional stability of the kerf.

[0026] The steps following S5 include: S6. Control the proportional reversing valve 13 to restore the positive pressure air source 11 input, so that the flexible mandrel 5 returns to the fluid state and retracts inward, thereby completing the workpiece unloading and release; After the dynamic vacuum adjustment during the cutting process is completed in S5, the method also includes the material release step in S6; after the cutting trajectory is executed, the industrial control computer 16 sends a control command to the proportional directional valve 13 to restore the input of the positive pressure air source 11, and at the same time cuts off or reduces the connection of the negative pressure air source 12. Positive pressure air enters the interior of the flexible mandrel 5, and air re-enters between the particles of the variable stiffness medium 7, which was originally in a state of particle blockage. The particle contact constraint is reduced, the near-solid support state is released, and it is restored to a fluid state that can flow and rearrange. The fluid state here is still a deformable state of the particle packing system under low constraint, not a true liquid; the internal and external pressures are rebalanced, and the flexible mandrel 5 contracts inward under its own elasticity. The outer surface of the flexible mandrel 5 separates from or the contact pressure with the inner wall of the main spindle motor tension housing is significantly reduced, thereby completing the workpiece unloading and release. To prevent local scratches on the workpiece due to the release speed exceeding the safety threshold, the industrial control computer 16 can adjust the control voltage of the proportional directional valve 13 back at a predetermined slope, so that the positive pressure establishment process lasts for 0.1 seconds to 1 second; if the workpiece size is larger than the set size threshold or the inner wall surface has specific requirements for roughness, the spindle 2 can be rotated at a predetermined low speed range after the positive pressure is restored, so that the workpiece can release local adhesion in circumferential micro-motion; S6 enables the composite internal support mechanism 4 to switch back to a low constraint state after completing the high-rigidity support function, which facilitates the removal of the workpiece by manual or robotic arms and provides initial compliance conditions for loading the next workpiece; through this release step, the equipment realizes a continuous process from fitting, locking, cutting, stiffness adjustment to unloading. To avoid misinterpreting the action of restoring the positive pressure air source 11 as continuously maintaining the 0.2MPa expansion pressure during the clamping stage, the positive pressure input in S6 is preferably a short-term low-flow air intake for relieving negative pressure or a slow air replenishment after being limited by the proportional reversing valve 13. Its function is to eliminate the negative pressure state in the sealed cavity 6, refill the particles and relieve the particle blockage, rather than continue to increase the external expansion clamping force of the flexible mandrel 5 on the inner wall of the workpiece. In specific execution, the industrial control computer 16 first controls the proportional directional valve 13 to switch from the negative pressure connection state to the positive pressure air supply state, so that the pressure in the sealed cavity 6 gradually rises from negative pressure to near normal pressure or slightly higher than normal pressure; after the variable stiffness medium 7 has recovered to the flowable rearrangement state, the proportional directional valve 13 is then controlled to enter the depressurization or small opening holding state, so that the flexible mandrel 5 no longer bears the internal pressure sufficient to maintain the wall expansion; Since the particle blockage has been removed at this time, the high-temperature resistant polyurethane elastic membrane 23 of the flexible mandrel 5 body retracts inward under the action of its own elastic recovery force and the recovery trend after the reaction force of the inner wall of the workpiece decreases, thus achieving separation from the inner wall of the stretching shell. Therefore, the causal relationship between positive pressure input, fluid state recovery and inward contraction is as follows: short-term positive pressure injection is used to release negative pressure lock-up, and after the lock-up is released, inward contraction is achieved through depressurization and elastic recovery. The two are sequential release processes.

[0027] This application has been described through the above embodiments; however, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit this application to the described embodiments. Those skilled in the art will understand that many more variations and modifications can be made based on the teachings of this application, and all such variations and modifications fall within the scope of protection claimed in this application.

Claims

1. A laser cutting equipment for producing a spindle motor stretch housing, characterized in that, include: Cutting frame (1); A rotating spindle (2) is correspondingly disposed on the cutting frame (1), and the center of the rotating spindle (2) passes through the central through hole (3); A composite internal support mechanism (4) is installed at the front end of the rotating spindle (2). The composite internal support mechanism (4) includes a flexible mandrel (5), a variable stiffness medium (7), and an air pipeline (8) that are configured to cooperate. A closed cavity (6) is formed inside the flexible mandrel (5). The variable stiffness medium (7) is filled in the closed cavity (6). The air pipeline (8) is nested inside the flexible mandrel (5). The outer surface of the flexible mandrel (5) is machined with a micro vortex cavity (9) formed by asymmetric inverted sawtooth grooves. A pneumatic control system (10) is matched and installed on the side of the cutting frame (1). The pneumatic control system (10) includes a positive pressure air source (11), a negative pressure air source (12) and a proportional reversing valve (13). The tail end of the air pipeline (8) passes through the central through hole (3) and is connected to the common end of the proportional reversing valve (13). The first input end and the second input end of the proportional reversing valve (13) are respectively connected to the positive pressure air source (11) and the negative pressure air source (12). A cutting head (14) is correspondingly positioned above the cutting frame (1), and a capacitive height adjustment sensor (15) is coaxially mounted at the end of the cutting head (14). An industrial computer (16) is connected to control the proportional directional valve (13) and the capacitive height sensor (15).

2. The laser cutting equipment for producing a spindle motor stretch housing according to claim 1, characterized in that, The micro vortex cavity (9) is defined along the injection direction of the high-pressure auxiliary cutting gas, and its windward slope is gentler than its leeward slope. The leeward side is set vertically, and the depth of the micro vortex cavity (9) is 0.5 mm.

3. The laser cutting equipment for producing a spindle motor stretch housing according to claim 1, characterized in that, The variable stiffness medium (7) is composed of polyhedral alumina ceramic particles (17) with a particle size of 50 to 100 μm.

4. The laser cutting equipment for producing a spindle motor stretch housing according to claim 1, characterized in that, The composite internal support mechanism (4) also includes a base flange (18) fixed at the front end of the rotating spindle (2). The gas pipeline network (8) is a stainless steel sintered tube (19) with micropores on its surface. The blind end (20) of the stainless steel sintered tube (19) is fixed to the center of the base flange (18) and extends into the variable stiffness medium (7).

5. The laser cutting equipment for producing a spindle motor stretch housing according to claim 1, characterized in that, The cutting head (14) is mounted on the gantry slider (21) above the cutting machine frame (1) via a linear motor (22), and the cutting head (14) is directly opposite the location of the composite inner support mechanism (4).

6. The laser cutting equipment for producing a spindle motor stretch housing according to claim 1, characterized in that, The positive pressure air source (11) provides compressed air at a pressure of 0.2 MPa, the negative pressure air source (12) provides negative pressure with a maximum vacuum of -80 kPa, and the valve core opening of the proportional directional valve (13) is controlled by the analog voltage signal output by the industrial control computer (16).

7. The laser cutting equipment for producing a spindle motor stretch housing according to claim 4, characterized in that, The main body of the flexible mandrel (5) is made of high temperature resistant polyurethane elastic membrane (23), and the open end of the flexible mandrel (5) is sealed and pressed on the outer circumference of the base flange (18) by a metal pressure ring (24).

8. A control method, applied to the laser cutting equipment for producing the spindle motor stretch housing as described in claim 1, characterized in that, include: S1. Control the proportional reversing valve (13) to open the positive pressure air source (11), and fill the flexible mandrel (5) with compressed air. Place the stretch shell to be cut on the outside of the composite inner support mechanism (4), and drive the flexible mandrel (5) and the variable stiffness medium (7) to expand outward and fit against the inner wall of the stretch shell. S2. Control the proportional reversing valve (13) to switch the negative pressure gas source (12) to extract the free gas between the variable stiffness medium (7), so that the variable stiffness medium (7) changes from a fluid state to a solid-like state; S3. Control the cutting head (14) to move down to the working height and make it face the position of the composite inner support mechanism (4). Start the laser beam and spray high-pressure auxiliary cutting gas, so that the high-pressure auxiliary cutting gas is injected into the micro vortex cavity (9) to form a high-speed micro vortex, thereby generating a pneumatic negative pressure directly below the cut. S4. Control the industrial computer (16) to read the high-frequency capacitance signal of the capacitive height adjustment sensor (15) and extract the time derivative of the high-frequency capacitance signal as the signal change rate. S5. Control the industrial control computer (16) to determine whether the signal change rate exceeds the preset basic threshold. If so, multiply the signal change rate by the pre-calibrated stiffness conversion coefficient to obtain the critical support stiffness requirement. According to the mechanical calculation model between the stiffness and vacuum degree of the variable stiffness medium (7), convert the critical support stiffness requirement into a target vacuum degree command. Convert the target vacuum degree command into a control voltage and adjust the valve core opening of the proportional directional valve (13) in real time.

9. The control method according to claim 8, characterized in that, The industrial control computer (16) has a support stiffness calculation algorithm running inside; Step S4 includes: The industrial control computer (16) is controlled to use a bandpass filter to extract the capacitor signal in the 1000 to 5000 Hz frequency band, and the sampling frequency of the industrial control computer (16) is set to 10 kHz.

10. The control method according to claim 8, characterized in that, The step S5 is followed by: S6. Control the proportional reversing valve (13) to restore the positive pressure air source (11) input, so that the flexible mandrel (5) returns to the fluid state and retracts inward, thereby completing the workpiece unloading and release.

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