Multi-station synchronous welding positioning device for spindle motor shell and method thereof

Abstract

The present application relates to the field of mechanical manufacturing and automatic welding assembly, in particular to a multi-station synchronous welding positioning device for a main shaft motor shell and a method thereof; the device comprises positioning main shaft, basic bulging capsule, phase change wrapping layer, opposing wave compensation liquid cavity and industrial control computer and other core components; the device synchronously introduces high-pressure fluid into the basic bulging capsule and the opposing wave compensation liquid cavity through a center pull rod flow channel; the core is that when the basic bulging capsule is driven by the hydraulic pressure to expand radially, the axial elongation generated by the wave compensation air chamber is utilized to push the push plate to apply axial thrust to the end of the bulging capsule for compensation; the present application effectively offsets the axial shrinkage phenomenon inherent in the traditional flexible bulging fastening, and significantly improves the axial positioning accuracy and shape stability of the thin-walled motor shell in the multi-station synchronous welding process.

Description

Technical Field

[0001] This invention relates to the field of mechanical manufacturing and automated welding assembly, specifically to a multi-station synchronous welding positioning device and method for spindle motor housings. Background Technology

[0002] In the multi-station synchronous welding process of thin-walled spindle motor housings, the thin housing wall and the need to withstand concentrated heat input from multiple welding torches simultaneously easily lead to localized thermal expansion, buckling, and residual deformation. To maintain the roundness and overall coaxiality of the housing, radial expansion and position retention are usually achieved through internal auxiliary tooling. Existing solutions for supporting and positioning the thin-walled motor housing generally employ mechanical rigid expansion sleeves or single elastic fluid-filled expansion bladder structures. Mechanical rigid expansion sleeves are difficult to accommodate minute initial roundness errors in the inner wall of the housing, and are prone to causing localized hard spot compression during clamping. Elastic expansion bladders, under pressure and radial expansion, are affected by the Poisson effect, leading to the opposite axial contraction, resulting in… This leads to a loss of alignment accuracy. Although these traditional static structures have a certain form and position support capability during the cold clamping stage, due to the constant contact stiffness they apply and the lack of a dynamic adjustment mechanism, after multi-station synchronous arc initiation, the absolute rigid constraint will completely restrict the local thermal expansion displacement of the shell, resulting in excessive stress accumulation in the heat input area and eventually causing irreversible local instability or buckling indentation. In addition, the high temperature and strong electromagnetic interference environment of multi-station welding makes it difficult to place conventional surface displacement sensors. Traditional devices cannot obtain the volume disturbance of local thermal deformation of the shell in real time and make adaptive interventions. The excessive concentration of heat and stress further exacerbates the risk of burn-through and deformation of thin-walled parts.

[0003] Therefore, how to overcome the inherent axial shrinkage phenomenon of flexible expansion and achieve indirect sensing of local thermal strain and dynamic adaptive unloading of support stiffness in complex welding environments 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 multi-station synchronous welding positioning device and method for spindle motor housing. Specifically, the technical solution of the present invention is as follows: A multi-station synchronous welding positioning device for spindle motor housing, comprising: The positioning spindle includes a central tie rod with an internal first fluid channel and a second fluid channel, the first fluid channel and the second fluid channel being connected to a hydraulic pump station and a high-frequency proportional vacuum pump, respectively; The basic expansion bladder is coaxially sleeved on the outside of the central tie rod. Its end is sealed and fixed to the central tie rod and its interior forms a primary main driving fluid cavity. The side wall of the first fluid channel has a radial hole that connects to the cavity. A phase change coating layer is coaxially wrapped around the basic expansion bladder. A closed secondary negative pressure intervention cavity filled with copper-based spherical particles is formed between the inner flexible silicone film and the outer flexible silicone film. The second fluid channel is connected to this cavity. The counter-current corrugated compensation fluid chamber is coaxially located at the end of the central tie rod. One end of the chamber is fixed to the central tie rod, and the other end is connected to an axial sliding push plate that abuts against the end of the basic expansion bladder. Its internal cavity is connected in parallel with the first fluid channel through a branch flow channel in the central tie rod. An industrial control computer controls the hydraulic pump station and the high-frequency proportional vacuum pump, and is connected to a high-frequency pressure sensor located at the inlet end of the first fluid channel.

[0005] In one possible implementation, the basic expansion bladder is a cylindrical hollow structure made of fluororubber.

[0006] In one possible implementation, the outer diameter of the phase change coating layer matches the inner diameter of the spindle motor housing to be welded.

[0007] In one possible implementation, the sidewall of the counter-current corrugated compensation fluid cavity has a corrugated folded structure, which can only undergo axial expansion and contraction deformation.

[0008] In one possible implementation, the second fluid channel is connected to the secondary negative pressure intervention chamber via a flexible conduit.

[0009] In one possible implementation, the high-frequency pressure sensor acquires transient pressure pulse signals within the primary main drive fluid chamber.

[0010] A multi-station synchronous welding and positioning method for spindle motor housing, including: S1. Control the hydraulic pump station to inject high-pressure hydraulic oil into the first fluid channel, drive the basic expansion bladder to generate radial expansion force to push the phase change wrapping layer to expand outward and fit the inner wall of the spindle motor housing; S2. During the radial expansion of the basic expansion bladder, the high-pressure hydraulic oil enters the counter-impact corrugated compensation fluid chamber through the branch flow channel, driving the counter-impact corrugated compensation fluid chamber to generate axial elongation and pushing the axial sliding push plate to apply axial thrust to the end of the basic expansion bladder. S3. At the moment of arc initiation when welding the spindle motor housing with a multi-station welding torch, control the high-frequency proportional vacuum pump to start at full power, so that it is in full load pulse width modulation duty cycle, and evacuate the air in the secondary negative pressure intervention cavity, so that the phase change coating layer is transformed into a rigid support state. S4. In real time, acquire the transient pressure pulse signal in the primary main drive fluid cavity collected by the high-frequency pressure sensor. Within a preset observation window, select the effective transient pressure pulse signal that falls within the preset frequency range and is higher than the preset amplitude, and perform time integration to obtain the pressure pulse integral change. S5. The internal volume change rate of the primary drive fluid cavity is converted by dividing the integral change of the pressure pulse by the duration of the observation window, and the local thermal strain rate of the spindle motor housing is calculated in reverse by combining the bulk modulus of the high-pressure hydraulic oil.

[0011] In one possible implementation, step S5 is followed by: When the local thermal strain rate is determined to be less than or equal to the preset elastic recovery limit threshold, the pulse width modulation duty cycle of the high-frequency proportional vacuum pump is maintained to maintain the rigid support state of the phase change coating layer. When the local thermal strain rate is determined to be greater than the preset elastic recovery limit threshold, the pulse width modulation duty cycle of the high-frequency proportional vacuum pump is reduced, the vacuum level in the secondary negative pressure intervention cavity is reduced, and the locking force between the copper-based spherical particles is weakened, causing the phase change coating layer to undergo microscopic rearrangement and relative sliding, absorbing and unloading the local thermal stress of the spindle motor housing.

[0012] In one possible implementation, after determining that the local thermal strain rate is greater than the preset elastic recovery limit threshold and reducing the pulse width modulation duty cycle of the high-frequency proportional vacuum pump, the method further includes: Continuously acquire the transient pressure pulse signal of the high-frequency pressure sensor; When it is determined that the pressure pulsation characteristics of the transient pressure pulse signal tend to be flat, that is, when it is determined that within multiple consecutive judgment windows, the peak amplitude of the transient pressure pulse signal in the current judgment window is lower than the peak amplitude of the previous window, and the fluctuation degree of the current judgment window is less than the fluctuation degree of the previous window, it is determined that the local thermal stress of the spindle motor housing has been released, the full power output of the high-frequency proportional vacuum pump is restored to re-establish the ultimate vacuum degree, and the phase change coating layer is restored to a rigid support state. When it is determined that the pressure pulsation characteristics of the transient pressure pulse signal have not become flat, i.e., the conditions for the decrease of the peak amplitude and fluctuation degree are not met, the reduced pulse width modulation duty cycle of the high-frequency proportional vacuum pump is maintained.

[0013] In one possible implementation, step S1 is followed by: The high-frequency proportional vacuum pump is controlled to be in the off state, so that the pressure inside the secondary negative pressure intervention chamber is normal. The copper-based spherical particles inside the secondary negative pressure intervention chamber are kept in a loose state, so that the phase change coating layer exhibits compliance, fills the irregular gaps in the inner wall of the spindle motor housing, and completes the macroscopic pose construction.

[0014] The present invention has the following beneficial effects: 1. This invention, by setting up a counter-impact corrugated compensation fluid chamber that is connected in parallel with the first fluid channel via a branch flow channel inside the central tie rod, allows the high-pressure hydraulic oil to simultaneously enter the counter-impact corrugated compensation fluid chamber through the branch flow channel when the basic expansion bladder generates radial expansion force driven by high-pressure hydraulic oil. This drives the bladder to generate axial elongation and pushes the axial sliding push plate to apply axial thrust to the end of the basic expansion bladder. This structure effectively counteracts the axial contraction tendency that accompanies the radial expansion of the basic expansion bladder, overcomes the inherent axial contraction phenomenon of traditional flexible expansion, and significantly improves the axial positioning accuracy and dimensional stability of the thin-walled spindle motor housing during multi-station synchronous welding. 2. This invention utilizes a high-frequency pressure sensor to collect transient pressure pulse signals within the primary drive fluid cavity to calculate the local thermal strain rate of the spindle motor housing, thus achieving indirect sensing of local thermal strain during multi-station synchronous welding processes. When the local thermal strain rate exceeds a preset elastic recovery limit threshold, the pulse width modulation duty cycle of the high-frequency proportional vacuum pump is reduced to decrease the vacuum level within the secondary negative pressure intervention cavity and weaken the locking force between copper-based spherical particles, thereby promoting microscopic rearrangement and relative sliding of the phase change coating layer. This dynamically absorbs and unloads the local thermal stress of the spindle motor housing, effectively preventing irreversible instability or buckling deformation of the housing caused by absolute rigid constraints. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the device; Figure 2 This is a schematic diagram of the basic expansion capsule and phase change encapsulation layer structure of the device; Figure 3 This is a schematic diagram of the cross-sectional structure of the device; Figure 4 This is a flowchart of the method of the present invention.

[0016] In the diagram: 1. Positioning spindle; 2. Central tie rod; 3. First fluid channel; 4. Second fluid channel; 5. Hydraulic pump station; 6. High-frequency proportional vacuum pump; 7. Basic expansion bladder; 8. Primary main drive fluid cavity; 9. Radial hole; 10. Phase change coating layer; 11. Inner flexible silicone membrane; 12. Outer flexible silicone membrane; 13. Secondary negative pressure intervention cavity; 14. Copper-based spherical particles; 15. Counter-impact corrugated compensation fluid cavity; 16. Axial sliding push plate; 17. Branch flow channel; 18. Industrial control computer; 19. High-frequency pressure sensor; 20. Flexible conduit. Detailed Implementation

[0017] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0018] Example 1: Combination Figure 1 and Figure 3 The multi-station synchronous welding positioning device for the spindle motor housing includes: The positioning spindle 1 includes a central tie rod 2 with an internal first fluid channel 3 and a second fluid channel 4. The first fluid channel 3 and the second fluid channel 4 are respectively connected to a hydraulic pump station 5 and a high-frequency proportional vacuum pump 6. Combination Figure 2 The basic expansion bladder 7 is coaxially sleeved on the outside of the central tie rod 2. Its end is sealed and fixed to the central tie rod 2 and its interior forms a primary main driving fluid cavity 8. The side wall of the first fluid channel 3 is provided with a radial hole 9 that connects to the cavity 8. A phase change coating layer 10 is coaxially wrapped around the basic expansion bladder 7. A secondary negative pressure intervention cavity 13 is formed between the inner flexible silicone film 11 and the outer flexible silicone film 12, which is sealed and filled with copper-based spherical particles 14. The second fluid channel 4 is connected to the cavity 13. The counter-current corrugated compensation fluid chamber 15 is coaxially located at the end of the central tie rod 2. One end of the chamber is fixed to the central tie rod 2, and the other end is connected to an axial sliding push plate 16 that abuts against the end of the basic expansion bladder 7. Its internal cavity is connected in parallel with the first fluid channel 3 through the branch flow channel 17 in the central tie rod 2. An industrial control computer 18 controls a hydraulic pump station 5 and a high-frequency proportional vacuum pump 6, and is connected to a high-frequency pressure sensor 19 located at the inlet end of the first fluid channel 3. The positioning spindle 1 serves as the load-bearing component and fluid distribution component of the device, and a central tie rod 2 extending along the axis forms an integral frame. The central tie rod 2 is equipped with an independent first fluid channel 3 and a second fluid channel 4. The first fluid channel 3 is used to transmit the high-pressure hydraulic oil output by the hydraulic pump station 5, and the second fluid channel 4 is used to transmit the negative pressure generated by the high-frequency proportional vacuum pump 6. The basic expansion bladder 7 is coaxially sleeved on the outside of the central tie rod 2. Its two ends are fixed to the outer wall of the central tie rod 2 by sealing flanges and locking elements. A closed annular space is formed between the inner wall of the basic expansion bladder 7 and the outer wall of the central tie rod 2. This annular space is the primary main drive fluid cavity 8. The side wall of the central tie rod 2 is provided with multiple radial holes 9, so that the hydraulic oil in the first fluid channel 3 can enter the primary main drive fluid cavity 8 and drive the basic expansion bladder 7 to expand radially. A phase change coating layer 10 is disposed on the outer periphery of the basic expansion bladder 7. The phase change coating layer 10 is surrounded by an inner flexible silicone film 11 and an outer flexible silicone film 12 to form a secondary negative pressure intervention cavity 13. The secondary negative pressure intervention cavity 13 is filled with copper-based spherical particles 14. After the second fluid channel 4 is connected to the secondary negative pressure intervention cavity 13, the high-frequency proportional vacuum pump 6 can adjust the contact state between the particles when pumping air, so that the phase change coating layer 10 can switch between a compliant state and a high-rigidity support state. The counter-pressure corrugated compensation fluid chamber 15 is located at the end of the central tie rod 2 and is connected in parallel with the first fluid channel 3 through the branch flow channel 17. Therefore, when the basic expansion bladder 7 is compressed and expands, the counter-pressure corrugated compensation fluid chamber 15 is simultaneously compressed and elongated, pushing the axial sliding push plate 16 to apply a reverse axial thrust to the end of the basic expansion bladder 7 to counteract the axial contraction tendency of the basic expansion bladder 7 caused by the Poisson effect. A high-frequency pressure sensor 19 is arranged at the inlet end of the first fluid channel 3 to collect transient pressure pulses in the hydraulic system. The industrial control computer 18 receives the pressure signal and controls the output of the hydraulic pump station 5 and the high-frequency proportional vacuum pump 6. In this way, mechanical support, fluid drive, negative pressure regulation and signal processing are combined in the same device to realize the positioning, axial suppression and thermal stress regulation of the thin-walled spindle motor housing in the multi-station synchronous welding process. Among them, the phase change coating layer 10 refers to the reversible switch of its overall mechanical state from a conforming and fitting state to a particle-locked and supported state. This phase change is a macroscopic mechanical state change of the particle system after being constrained by negative pressure, rather than a thermodynamic phase change such as melting, solidification or crystal structure change of the copper-based spherical particle 14 material itself. Its physical basis is that when the secondary negative pressure intervention chamber 13 is at normal pressure or the first preset vacuum degree, the normal clamping force between particles is lower than the frictional resistance threshold of particle rearrangement. The particle group can undergo local flow and rearrangement under the inner and outer silicone film. Therefore, the phase change coating layer 10 can adapt to the small roundness deviation and surface irregularity of the inner wall of the spindle motor housing. When the secondary negative pressure intervention chamber 13 is drawn to the second preset vacuum level, the external pressure causes the inner flexible silicone film 11 and the outer flexible silicone film 12 to press the particle group, the number of contact points between the particles increases and the friction constraint is enhanced, and the particle group changes from a rearrangeable state to a locked state that is difficult to flow. Therefore, the phase change coating layer 10 as a whole exhibits the equivalent stiffness required for locking support. Since the state switching is controlled by the degree of negative pressure rather than directly triggered by temperature, its mechanism is as follows: heat input mainly changes the local deformation and stress state of the shell, and the negative pressure system determines whether the phase change wrapping layer 10 maintains the locked support or releases the local compliance based on the deformation and stress state. From the perspective of the internal logic of the device, the hydraulic support subunit, the negative pressure stiffness switching subunit, and the pressure sensing subunit are not isolated from each other; the hydraulic support subunit consists of a hydraulic pump station 5, a first fluid channel 3, a radial hole 9, and a primary main drive fluid cavity 8, and its function is to establish the macroscopic radial support force of the basic expansion bladder 7. The negative pressure stiffness switching subunit consists of a high-frequency proportional vacuum pump 6, a second fluid channel 4, and a secondary negative pressure intervention chamber 13. Its function is to change the equivalent stiffness of the phase change coating layer 10 on the basis of already adhering to the wall. The pressure sensing subunit consists of a high-frequency pressure sensor 19 and an industrial control computer 18. Its function is to identify the pressure disturbance transmitted back to the hydraulic system by the thermal deformation of the shell during the welding process. The data and action path of the three are as follows: first, the hydraulic system establishes contact with the wall, then the vacuum system determines the equivalent stiffness of the support after contact with the wall, and the pressure sensor feeds back the volume disturbance caused by the local thermal deformation of the shell to the industrial control computer 18, and the industrial control computer 18 then adjusts the output of the vacuum system in the opposite direction. Therefore, the device represents a closed-loop control chain of local thermal deformation of the shell, compression of the phase change wrapping layer 10, volume response of the basic expansion bladder 7, hydraulic pressure pulsation, vacuum adjustment by the control computer, and stiffness redistribution of the phase change wrapping layer 10, rather than a single static expansion structure. To ensure the fluidity of the phase change coating layer 10 in the compliant state and the equivalent stiffness in the locked state, the copper-based spherical particles 14 filled in the secondary negative pressure intervention cavity 13 preferably adopt a multi-particle-size graded mixed structure. Specifically, the copper-based spherical particles 14 include coarse particles with a diameter of 0.5-1.0 mm and fine particles with a diameter of 0.1-0.2 mm, which are mixed in a mass ratio of 3:1 to 4:1. The coarse particles form the main load-bearing skeleton under negative pressure locking, providing macroscopic support stiffness. The fine particles play a lubricating role under normal pressure to enhance compliance, and fill the pores between the coarse particles under negative pressure, significantly increasing the number of contact points between particles, thereby improving the overall friction self-locking effect. In addition, copper-based material is selected not only to obtain mechanical strength that meets the support threshold, but also to take advantage of its performance that meets the preset thermal conductivity, so that the welding heat of the spindle motor housing can be quickly conducted to the base expansion bladder 7 and the central tie rod 2, avoiding excessive heat concentration that could cause the housing to burn through or be severely deformed.

[0019] The basic expansion capsule 7 is a cylindrical hollow structure made of fluororubber; The basic expansion bladder 7 is made of fluororubber and forms a cylindrical hollow structure arranged along the axis of the central tie rod 2. In this invention, fluororubber is used to balance sealing performance, oil resistance and heat resistance, so that the primary main driving fluid cavity 8 can maintain a stable seal during repeated pressurization and depressurization, and maintain the elastic recovery ability of the bladder wall material under the influence of welding heat input. The significance of the cylindrical hollow structure lies in its uniform radial deformation. After being subjected to the hydraulic oil pressure input by the first fluid channel 3, it can form a continuous external support force in the circumferential direction, avoiding stress concentration on the inner wall of the thin-walled spindle motor housing caused by local hard points. The basic expansion bladder 7 is preferably a fluororubber cylinder with uniform thickness. Both ends are sealed and fixed to the central tie rod 2 by metal flanges. After the hydraulic oil enters the first-stage main drive fluid chamber 8, the cylindrical bladder wall expands in a controllable manner in the radial direction, causing the outer phase change wrapping layer 10 to move outward as a whole and fit against the inner wall of the spindle motor housing. With this material and structure, the basic expansion bladder 7 can not only undertake the initial expansion function during macroscopic pose construction, but also serve as an intermediate flexible transmission layer for transmitting pressure pulses to the hydraulic system through the volume change of the phase change wrapping layer 10.

[0020] The outer diameter of the phase change coating layer 10 matches the inner diameter of the spindle motor housing to be welded; The outer diameter of the phase change wrapping layer 10 is designed to match the inner diameter of the spindle motor housing to be welded. This means that the outer diameter of the phase change wrapping layer 10 in its natural state is slightly smaller than the inner diameter of the spindle motor housing. After the basic expansion bladder 7 is compressed, it can compensate for this small gap and form a wall-attached support. Specifically, the size range of the single-sided assembly clearance formed between the outer diameter in its natural state and the inner diameter of the spindle motor housing is limited to: greater than the minimum sliding clearance required for the device to be inserted into the spindle motor housing without obstruction, and less than the effective radial expansion stroke of the basic expansion bladder 7 under the maximum rated hydraulic pressure. The purpose of this matching relationship is to ensure that the positioning device can be smoothly inserted into the spindle motor housing during the clamping stage, while avoiding interference friction force exceeding the allowable threshold between the phase change coating layer 10 and the inner wall of the housing during insertion. When the hydraulic pump station 5 is working, the basic expansion bladder 7 pushes the phase change wrapping layer 10 to expand outward, and the outer surface of the phase change wrapping layer 10 is in full contact with the inner wall of the shell. The copper-based spherical particles 14 filling the space between the inner flexible silicone film 11 and the outer flexible silicone film 12 can fill the irregular micro gaps in the inner wall of the shell under normal pressure, and form a continuous support under negative pressure. The matching of the outer and inner diameters enables the phase change coating layer 10 to have a fitting ability in the compliant state and a sufficient support area in the negative pressure locking state, thereby taking into account the convenience of clamping, the uniformity of circumferential contact and the support stability during welding.

[0021] The sidewall of the counter-current corrugated compensation fluid chamber 15 has a corrugated folded structure, which can only undergo expansion and contraction deformation along the axial direction. The sidewall of the counter-flush corrugated compensation liquid chamber 15 adopts a corrugated folded structure, preferably a metal bellows structure. This structure means that when its internal cavity is connected to the same hydraulic pressure as the first fluid channel 3, the corrugated compensation air chamber mainly extends or retracts along the central tie rod 2 axially, while the radial dimension remains basically unchanged. This feature is designed to directly convert the hydraulic energy in the first fluid channel 3 into axial thrust, so as to avoid the compensation air chamber itself from encroaching on the internal space of the spindle motor housing or interfering with the radial support of the basic expansion bladder 7 when it expands radially. Since the basic bulging bladder 7 exhibits an axial contraction tendency coupled with radial expansion when compressed, the corrugated folding structure provides an axial displacement output opposite to this contraction direction, and the axial sliding push plate 16 thus applies a stable thrust to the end of the basic bulging bladder 7. By limiting the corrugated compensation chamber to expand and contract only along the axial direction, the compensation action can be aligned with the direction of the parasitic axial force to be counteracted, thereby improving the counterbalancing effect and maintaining the overall dimensional stability of the device.

[0022] The second fluid channel 4 is connected to the secondary negative pressure intervention chamber 13 via the flexible conduit 20; The second fluid channel 4 is connected to the secondary negative pressure intervention chamber 13 by a flexible conduit 20. The flexible conduit 20 passes through the sealing area at the end of the basic expansion bladder 7 and is sealed and connected to the secondary negative pressure intervention chamber 13. To achieve physical isolation of the pipeline, the end of the basic expansion bladder 7 is provided with a metal sealing flange fixed to the central tie rod 2. The flexible conduit 20 passes independently through a dedicated wire sealing hole opened on the metal sealing flange, thereby achieving negative pressure connection between the second fluid channel 4 and the second negative pressure intervention chamber 13 without damaging the hydraulic oil sealing integrity in the primary main drive fluid chamber 8. The purpose of using the flexible catheter 20 is to accommodate the radial displacement and local deformation of the basic expansion bladder 7 during the pressurization process, and to avoid the rigid connector from damaging the sealing of the secondary negative pressure intervention cavity 13 under the action of relative displacement; When the high-frequency proportional vacuum pump 6 is working, the negative pressure is transmitted to the flexible conduit 20 through the second fluid channel 4, and then to the secondary negative pressure intervention chamber 13 through the flexible conduit 20. After the air in the secondary negative pressure intervention chamber 13 is extracted, the contact pressure between the copper-based spherical particles 14 increases, and the particle group changes from a loose state to a locked state. The flexible conduit 20 also facilitates the overall expansion and contraction of the phase change encapsulation layer 10 along with the basic expansion bladder 7, and will not form a local rigid constraint on the circumferential support of the phase change encapsulation layer 10. Therefore, it is beneficial to maintain the uniform force on the phase change encapsulation layer 10 along the circumferential direction.

[0023] High-frequency pressure sensor 19 acquires transient pressure pulse signals within the primary main drive fluid chamber 8; The high-frequency pressure sensor 19 is installed on the pipeline at the inlet end of the first fluid channel 3. Its target is the transient pressure pulse signal transmitted back by the hydraulic oil from the primary main drive fluid chamber 8. The formation mechanism of the transient pressure pulse signal in this invention is as follows: when the spindle motor housing undergoes local thermal expansion or slight inward buckling under the action of welding heat input, it will squeeze the phase change wrapping layer 10 that is attached to it. The slight change in volume of the phase change wrapping layer 10 is further transmitted to the primary main drive fluid cavity 8 through the basic expansion bladder 7, causing the hydraulic oil in it to have corresponding pressure fluctuations. The high-frequency pressure sensor 19 has a sufficient response speed to distinguish the pressure drop and pressure pulsation characteristics that occur in a short time during the welding process; since the sensor is located in the hydraulic line far away from the welding arc, the influence of high temperature and strong electromagnetic environment on measurement accuracy can be reduced. After acquiring the transient pressure pulse signal, the industrial control computer 18 can use it as the input for subsequent thermal strain rate calculation and vacuum adjustment, thereby enabling the primary main drive fluid cavity 8 to have both power transmission and deformation sensing functions.

[0024] Example 2: Combination Figure 4 A multi-station synchronous welding and positioning method for spindle motor housing, including: S1. Control the hydraulic pump station 5 to inject high-pressure hydraulic oil into the first fluid channel 3, drive the basic expansion bladder 7 to generate radial expansion force to push the phase change wrapping layer 10 to expand outward and fit the inner wall of the spindle motor housing. S2. During the radial expansion of the basic expansion bladder 7, high-pressure hydraulic oil enters the counter-impact corrugated compensation fluid chamber 15 through the branch flow channel 17, driving the counter-impact corrugated compensation fluid chamber 15 to generate axial elongation and pushing the axial sliding push plate 16 to apply axial thrust to the end of the basic expansion bladder 7. S3. At the moment of arc initiation when welding the spindle motor housing with a multi-station welding torch, control the high-frequency proportional vacuum pump 6 to start at full power, so that it is in full load pulse width modulation duty cycle, and evacuate the air in the secondary negative pressure intervention chamber 13, so that the phase change coating layer 10 is transformed into a rigid support state. S4. Real-time acquisition of transient pressure pulse signals in the primary main drive fluid cavity 8 collected by high-frequency pressure sensor 19. Within a preset observation window, select effective transient pressure pulse signals that fall within a preset frequency range and are higher than a preset amplitude, and perform time integration to obtain the integral change of pressure pulse. S5. The pressure pulse integral change is divided by the observation window duration to convert it into the internal volume change rate of the primary drive fluid cavity 8, and the local thermal strain rate of the spindle motor housing is calculated in reverse by combining the bulk elastic modulus of the high-pressure hydraulic oil. The positioning method is accomplished by the unified scheduling of the hydraulic pump station 5, the high-frequency proportional vacuum pump 6, and the high-frequency pressure sensor 19 by the industrial control computer 18. When S1 is executed, the hydraulic pump station 5 supplies high-pressure hydraulic oil to the first fluid channel 3. The hydraulic oil enters the first-stage main drive fluid cavity 8 through the radial hole 9 on the central tie rod 2. After being compressed, the basic expansion bladder 7 expands and displaces in the circumferential direction, and transmits the displacement to the phase change wrapping layer 10, so that the phase change wrapping layer 10 forms a surface contact with the inner wall of the spindle motor housing. When S2 is executed, the same pressure source enters the internal cavity of the counter-impacting corrugated compensation liquid chamber 15 through the branch flow channel 17. The corrugated compensation air chamber extends axially, and the axial sliding push plate 16 contacts the end of the base expansion bladder 7 and applies axial thrust. This thrust is used to counteract the axial contraction force generated by the Poisson effect of the base expansion bladder 7, thereby maintaining the axial alignment stability of the spindle motor housing. When executing S3, the high-frequency proportional vacuum pump 6 is controlled to run at full power at the moment of arc ignition of the multi-station welding torch. The air in the secondary negative pressure intervention chamber 13 is quickly extracted, the contact between the copper-based spherical particles 14 is enhanced, and the phase change coating layer 10 changes from a compliant state to a high-rigidity support state to improve the compressive strength of the spindle motor housing during the welding stage. When executing S4, the high-frequency pressure sensor 19 continuously collects the pressure signal in the first fluid channel 3. The industrial control computer 18 filters and extracts features from the pressure signal, filters the preset frequency and amplitude information related to welding heat deformation, and performs time integration on the pressure change to obtain the pressure pulse integral change. When executing S5, the industrial control computer 18 calculates the volume change rate inside the primary drive fluid cavity 8 based on the integral change of the pressure pulse, and then maps the volume change in the hydraulic system to the local thermal strain rate of the spindle motor housing by combining the bulk elastic modulus of the hydraulic oil. This method integrates clamping support, axial compensation, stiffness switching, and thermal deformation sensing into a continuous process, enabling the thin-walled spindle motor housing to maintain positioning accuracy during multi-station synchronous welding. The preset frequency is not arbitrarily selected, but refers to the pressure pulsation frequency band that is pre-identified in the no-load clamping state and the standard welding sample calibration state, and corresponds to the local expansion and contraction response of the shell caused by the welding heat input. The industrial control computer 18 first stores the pulsation frequency band of the hydraulic pump station 5 itself, the working frequency band of the vacuum pump, and the frequency band corresponding to the electromagnetic interference of the welding torch, and then compares the pressure signal collected in real time with the reference frequency band, retaining only the frequency component that matches the thermal deformation response of the shell. The preset amplitude refers to the lower limit of the effective pressure fluctuation amplitude that is higher than the system static noise baseline and can characterize the extrusion phase change coating layer 10 on the inner wall of the shell. It is determined by continuously sampling in the unwelded but taut and vacuum-locked state to obtain the pressure noise bandwidth and noise peak value. Then, pressure changes higher than the noise peak value are used as effective pulse inputs to avoid misjudging the hydraulic pipeline background disturbance as a thermal deformation signal. The processing logic of S4 and S5 is executed in the following order: the high-frequency pressure sensor 19 outputs the original transient pressure signal, the industrial control computer 18 reads it according to a fixed sampling period and forms a time series; the stable pressure when S3 is completed and the welding torch has not yet significantly heated the shell is used as the reference pressure, and the pressure increment at each sampling time relative to the reference pressure is calculated. The pressure increment sequence is bandpass filtered, retaining only pulse components that fall within a preset frequency range and have an amplitude higher than a preset amplitude. These components are then accumulated chronologically to obtain the integral change of the pressure pulses. Specifically, the integral change of the pressure pulses... The calculation logic is as follows: in, For discrete summation, This is the integral change of the pressure pulse. The starting time of the observation window. For discrete sampling times, The effective transient pressure retained after bandpass screening. As the reference pressure, For the duration of the observation window, The sampling period is denoted as ; the physical meaning of the integral change of the pressure pulse is the degree of cumulative pressure shift experienced by the primary main drive fluid cavity 8 due to external thermal deformation disturbance within a certain observation period. It is used to characterize the overall strength of the transmission of local thermal expansion and contraction of the shell to the hydraulic system, rather than an isolated peak value at a single moment. When the pressure signal is converted into the internal volume change rate, the industrial control computer 18 does not directly output the calculation result without intermediate parameters. Instead, it first converts the pressure pulse integral change into the cumulative volume change of the primary main drive fluid cavity 8 within the observation window based on the corresponding relationship that the equivalent volume of the cavity decreases when the hydraulic oil is compressed and the equivalent volume of the cavity increases when the pressure increases. Divide the cumulative volume change by the corresponding observation time to obtain the internal volume change rate. The internal volume change rate is used to indicate the speed at which the spindle motor housing transmits deformation to the hydraulic system through the phase change wrapping layer 10 and the basic expansion bladder 7. It is an intermediate quantity for subsequent back-calculation of the local thermal strain rate. The industrial control computer 18 combines the internal volume change rate with the effective contact length, the effective pressure circumferential area of ​​the phase change coating layer 10, and the initial geometric dimensions of the corresponding segment of the spindle motor housing, which were pre-entered during clamping, to first obtain the equivalent radial deformation of the housing per unit time. Then, this equivalent radial deformation is normalized relative to the corresponding initial dimensions to obtain the local thermal strain rate. The specific conversion logic is as follows: in, For local thermal strain rate, This is the integral change of the pressure pulse. For the duration of the observation window, The bulk modulus of elasticity of hydraulic oil. This is the initial equivalent volume of the primary driving fluid cavity 8. This represents the effective contact area between the phase change coating layer 10 and the shell. The initial inner diameter of the shell; the local thermal strain rate in this invention refers to the degree of deformation per unit time in a local area of ​​the shell caused by welding heat input. This amount serves as a direct control input for subsequent judgment on whether to maintain rigid support or appropriately release the vacuum. In the above calculation process, the bulk modulus of hydraulic oil is adopted as the test calibration value or the pre-stored value corresponding to the oil type. When the oil type is changed, it is only necessary to update the parameter in the industrial control computer 18 to keep the derivation chain from pressure change to volume change and then from volume change to thermal strain rate consistent. The actual logic model used in S4 to S5 is a set of logic models for indirectly sensing the thermal deformation of the shell. The purpose of this logic model is not to directly measure the displacement near the weld, but to indirectly characterize the strength of the local thermal deformation of the shell by utilizing the pressure response of the hydraulic cavity under the conditions of welding torch arc, high temperature and multi-station synchronous operation where it is inconvenient to place displacement sensors. The logical model includes, in sequence, a signal filtering unit, a hydraulic volume mapping unit, and a housing strain calculation unit: The signal filtering unit receives the original pressure time sequence output by the high-frequency pressure sensor 19, and obtains the effective pressure pulse after removing the pulsation of the hydraulic pump station 5 itself, the working disturbance of the vacuum pump, and the electromagnetic interference of the welding torch. The hydraulic volume mapping unit corresponds the effective pressure pulse to the equivalent volume contraction or expansion trend of the primary main drive fluid cavity 8 within the observation window; the shell transformation calculation unit, combined with the geometric parameters of the clamping contact area, converts the equivalent volume change into the equivalent radial deformation of the shell per unit time, and finally obtains the local thermal strain rate. Thus, the data flow is clearly manifested as: original pressure signal - effective pressure pulse - cumulative pressure offset - cavity volume change rate - local radial deformation rate - local thermal strain rate; The overall logical model represents the real physical relationship as follows: the welding heat input causes local thermal expansion, local buckling tendency or retraction of the spindle motor housing. This local geometric change is transmitted to the basic expansion bladder 7 through the phase change wrapping layer 10 that is attached to it, which in turn causes the hydraulic oil in the primary main drive fluid cavity 8 to change the pressure state, forming a transient pressure pulse that can be captured by the high-frequency pressure sensor 19. Therefore, the pressure change is not an isolated electrical signal, but the result of the coupling transmission of the shell thermal deformation along the path of the shell inner wall—phase change coating layer 10—basic expansion bladder 7—hydraulic oil; in order to avoid mistaking local contact loosening, pipeline elastic rebound or pump source background pulsation as thermal strain, the industrial control computer 18 preferably performs repeated calculations with a fixed length observation window, and takes into account the directionality of the pressure pulse: when the effective pressure pulse as a whole shows a positive pressure increase trend, it is determined that the local compression of the shell on the phase change coating layer 10 is dominant; When the effective pressure pulse shows an overall decompression trend, it is determined that the local retraction of the shell or the stress release in the contact area is dominant. When the two alternate, the cumulative offset within the window is used to characterize the strength of the comprehensive thermal deformation during that period. In this way, the calculation results of S4 and S5 correspond one-to-one with the force transmission path of the device, realizing the accurate conversion of physical quantities.

[0025] Step S5 is followed by: When the local thermal strain rate is determined to be less than or equal to the preset elastic recovery limit threshold, the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6 is maintained to keep the phase change coating layer 10 in a rigid support state. When the local thermal strain rate is determined to be greater than the preset elastic recovery limit threshold, the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6 is reduced, the vacuum level in the secondary negative pressure intervention chamber 13 is reduced, and the locking force between the copper-based spherical particles 14 is weakened, so as to promote the micro-rearrangement and relative sliding of the phase change coating layer 10, and absorb and unload the local thermal stress of the spindle motor housing. After obtaining the local thermal strain rate, the industrial control computer 18 compares the value with a preset elastic recovery limit threshold. The preset elastic recovery limit threshold represents the upper limit of the thermal strain rate at which the spindle motor housing material can still maintain elastic recovery under the current welding process. This threshold can be preset and stored in the industrial control computer 18 according to the material grade, wall thickness and welding heat input conditions. When the local thermal strain rate is less than or equal to the threshold, the industrial control computer 18 maintains the current pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6, so that the secondary negative pressure intervention chamber 13 maintains the first preset vacuum degree, the copper-based spherical particles 14 maintain the target rigid locking state, and the phase change coating layer 10 continues to provide stable rigid support. When the local thermal strain rate exceeds the threshold, the industrial control computer 18 lowers the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6, and the vacuum level in the secondary negative pressure intervention chamber 13 decreases accordingly. The normal pressure and frictional constraint between particles are weakened, and micro-rearrangement and particle slippage can occur in the local area of ​​the phase change coating layer 10. The controlled slip consumes the stress accumulation caused by local thermal expansion, which reduces the stress level in the contact area between the inner wall of the spindle motor housing and the phase change coating layer 10, thereby reducing the probability of irreversible buckling of the thin-walled housing. The characteristic of this control method is that the vacuum degree is not fixed, but is adjusted according to the calculated thermal strain rate, so that the support stiffness and thermal stress release capacity change with the welding state. The preset elastic recovery limit threshold distinguishes between thermal deformation that allows for continued rigid constraint and thermal deformation that requires moderate release of constraint, serving as the boundary for the industrial control computer 18 to switch control strategies. The physical meaning of this threshold is: the maximum rate of thermal strain growth that the housing can withstand per unit time without causing irreversible buckling, residual indentation or exceeding the allowable ellipticity deviation in the local area of ​​the spindle motor housing. The preferred method for determining the preset elastic recovery limit threshold is pre-calibration. Specifically, a sample with the same material grade, wall thickness, and cylinder size as the final product is selected, and multiple trial welds are performed under the same multi-station welding torch arrangement, welding current, welding speed, and clamping vacuum conditions as the final welding. During each trial weld, the local thermal strain rate calculated by the high-frequency pressure sensor 19 is recorded, and after welding, it is checked whether permanent deformation exceeding the allowable range occurs at the corresponding position. The highest set of local thermal strain rates that can still maintain post-weld elastic recovery and dimensional compliance, or the values ​​after leaving a safety margin on the highest value, are written into the industrial control computer 18 as the preset elastic recovery limit threshold. With this method, the source of the threshold corresponds to the specific material and welding condition, which is convenient for repeated implementation. In terms of control process, the industrial control computer 18 does not perform only one comparison, but in the welding stage, it periodically repeats the judgment chain of collecting thermal strain rate - comparing with threshold - outputting vacuum pump duty cycle according to continuous sampling window; When the local thermal strain rate is determined to be less than or equal to the threshold, it means that the current local deformation is still within the range that can be constrained by rigid support and can be recovered in subsequent cooling. Therefore, the current pulse width modulation duty cycle is maintained and the particle locking force is not actively released. When the local thermal strain rate is determined to be greater than the threshold, it means that continuing to maintain the original ultimate vacuum level may cause the local thermal stress to accumulate too quickly. Based on this, the industrial control computer 18 uses the comparison result as a trigger condition to reduce the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6, so that the phase change coating layer 10 switches from a strongly locked state to a controlled compliant state. The reduced duty cycle can be determined by a graded adjustment method, that is, the higher the thermal strain rate, the greater the reduction in the target duty cycle. Alternatively, a lookup table method can be used, whereby the industrial control computer 18 outputs control quantities according to a pre-established correspondence between the thermal strain rate range and the target duty cycle range, thereby improving the accuracy and observability of the control process; preferably, the adjustment logic for reducing the pulse width modulation duty cycle adopts the following quantitative calculation method: in, For the target pulse width modulation duty cycle, This represents the current pulse width modulation duty cycle. The preset proportional adjustment coefficient has its unit of measurement limited to 1. Used to compensate for the difference in thermal strain rate Dimensionality, thus making the output a dimensionless percentage constant to match the duty cycle; This is the currently calculated local thermal strain rate. To preset the elastic recovery limit threshold, To maintain the minimum duty cycle lower limit required for the phase change coating layer 10 to maintain basic wall contact; This is a function to find the maximum value, used to select the item with the larger value within the parentheses; Proportional adjustment coefficient It is not an arbitrary value. Its physical essence represents the amount of negative pressure release required for a unit over-limit thermal strain rate. This coefficient is obtained by experimental calibration based on the maximum pumping speed of the high-frequency proportional vacuum pump 6, the effective volume of the secondary negative pressure intervention chamber 13, and the stiffness attenuation characteristics of the copper-based spherical particles 14 in the phase change coating layer 10. This calculation logic enables precise dynamic matching of the vacuum release amplitude, ensuring a smooth and controllable stress unloading process. The above control does not mean that the greater the thermal strain rate, the more relaxed the constraint will be until the support is completely lost. Rather, it means that the local constraint strength is released in a limited manner while maintaining the basic wall contact required for positioning. The causal relationship is as follows: because a high vacuum level will enhance the degree of particle group locking, the phase change coating layer 10 has a stronger constraint on the local thermal expansion of the shell; when the local thermal strain rate exceeds the threshold, if the original high vacuum level is maintained, the thermal expansion of the shell is more likely to be transformed into compressive instability or residual stress accumulation locally. Therefore, the industrial control computer 18 reduces the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6, so that the vacuum level of the secondary negative pressure intervention chamber 13 is reduced to a range that allows controlled slippage of particles, rather than directly releasing the negative pressure or canceling the hydraulic expansion. Thus, the phase change wrapping layer 10 still maintains continuous surface contact and basic support for the spindle motor housing, only releasing excessive constraints in areas where local thermal stress is concentrated. In this invention, micro-rearrangement and relative sliding refer to the process in which, after the negative pressure constraint is weakened, several local contact chains first become unstable, and then drive adjacent particles to find a new force equilibrium position, thereby forming a chain displacement release process within a limited range. This process does not require large-scale particle dispersion, nor does it mean that the phase change coating layer 10 collapses as a whole. Instead, the particle group undergoes slight positional adjustments in local areas under the wrapping of the outer flexible silicone film 12 and the inner flexible silicone film 11. Its technical effect is that the additional load generated by the local thermal expansion of the shell is no longer entirely borne by the shell wall, but is partially converted into internal frictional dissipation and rearrangement energy dissipation of the particle group, thus reducing the probability of accumulating higher compressive stress at the same location. The aforementioned technical features make the technical logic of reducing duty cycle—reducing vacuum degree—weakening particle locking—releasing local stress more direct and complete; To more clearly illustrate the dynamic adjustment logic described above, a specific quantitative deduction example is provided here: Assume that under a certain welding condition, a preset elastic recovery limit threshold is set. Calibrated at 0.05 / s, this is the lower limit of the minimum duty cycle required to maintain basic wall-attached contact of the phase change coating layer 10. Set to 30%, proportional adjustment coefficient The pulse width modulation duty cycle is set to 1000, and the current high-frequency proportional vacuum pump 6's duty cycle is... 100% full load; When the industrial control computer 18 calculates the local thermal strain rate within an observation window When the surge reaches 0.08 / s, it exceeds the threshold of 0.05 / s, triggering the release mechanism; according to the aforementioned calculation logic, the decrease in the target duty cycle is... Therefore, the target duty cycle Adjusted to Since 70% is greater than the lower limit of 30%, the industrial control computer 18 will reduce its duty cycle to 70%. If the thermal strain rate continues to increase to 0.15 / s in the next window, the calculated decrease is... The theoretical duty cycle is However, it is limited by the lower limit. The actual output duty cycle will be limited and kept at 30%; Through this explicit linear proportional adjustment and lower limit cutoff rule, the system can quickly respond to drastic changes in thermal stress while maintaining the minimum duty cycle constraint of the phase change coating layer 10 in basic wall contact, thus achieving parameterization and traceability of the vacuum degree control process.

[0026] After determining that the local thermal strain rate exceeds the preset elastic recovery limit threshold and reducing the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6, the process also includes: Continuously acquire transient pressure pulse signals from the high-frequency pressure sensor 19; When the pressure pulsation characteristics of the transient pressure pulse signal tend to be flat, that is, when the peak amplitude of the transient pressure pulse signal in the current judgment window is lower than the peak amplitude of the previous window and the fluctuation degree of the current judgment window is less than the fluctuation degree of the previous window, it is determined that the local thermal stress of the spindle motor housing has been released, and the high-frequency proportional vacuum pump 6 is restored to full power output to re-establish the ultimate vacuum degree, so that the phase change coating layer 10 is restored to a rigid support state. When the pressure pulsation characteristics of the transient pressure pulse signal do not become flat, i.e., the conditions for the decrease of the peak amplitude and fluctuation degree are not met, the pulse width modulation duty cycle of the reduced high-frequency proportional vacuum pump 6 is maintained. After the industrial control computer 18 has reduced the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6 to release local thermal stress, the high-frequency pressure sensor 19 continues to continuously acquire transient pressure pulse signals in the first fluid channel 3; the industrial control computer 18 performs real-time analysis on the subsequently acquired pressure pulses, comparing their frequency distribution, peak amplitude, and degree of fluctuation per unit time. When the pressure pulsation characteristics tend to be flat, it indicates that the volume disturbance caused by the local thermal expansion of the spindle motor housing to the phase change wrapping layer 10 and the basic expansion bladder 7 has been weakened, and the thermal stress release process of the corresponding part is nearing completion. At this time, the industrial control computer 18 restores the high-frequency proportional vacuum pump 6 to full power output, the secondary negative pressure intervention chamber 13 re-establishes the first preset vacuum degree, the copper-based spherical particles 14 are locked, and the phase change coating layer 10 returns to a rigid support state to maintain the roundness and axial stability of the subsequent welding section of the spindle motor housing. When the pressure pulsation characteristics have not yet leveled off, the industrial control computer 18 maintains the reduced pulse width modulation duty cycle, so that the phase change coating layer 10 continues to retain a certain degree of compliance in the local area until the new pressure pulsation analysis results meet the conditions for restoring rigid support; through continuous acquisition and condition judgment, the vacuum degree recovery action corresponds to the thermal stress release process, avoiding premature restoration of rigidity and hindering local thermal expansion. Among them, the pressure pulsation characteristics tending to be flat is a judgment state used to restore rigid support, indicating that within multiple consecutive sampling windows, the pressure signal has significantly weakened compared to the violent fluctuations before the duty cycle was reduced. Its judgment does not rely on a single peak value, but comprehensively examines at least one or more of the following characteristics: whether the pressure peak amplitude decreases, whether the number of pulses exceeding the preset amplitude per unit time decreases, whether the energy in the main pulsation frequency band decays, and whether the mean square fluctuation between adjacent sampling windows decreases. The preset amplitude is preferably adopted as the lower limit of the effective pressure pulse recognition, so the judgment standard is consistent before and after; the industrial control computer 18 preferably executes the recovery judgment process according to a fixed judgment window; the process is as follows: after reducing the pulse width modulation duty cycle of the high-frequency proportional vacuum pump 6, the pressure pulse data in the current judgment window is continuously acquired; the peak amplitude, effective pulse count and fluctuation degree in the window are calculated; The quantitative calculation rule for the degree of fluctuation is as follows: extract the discrete deviation of all effective pressure pulses in the current judgment window relative to the reference pressure, calculate the mean square error of these deviations, and use this mean square error value as a specific indicator to characterize the degree of fluctuation; compare the result of this window with the result of the previous window and the result of the reference window when the release control action is triggered. If two or more consecutive judgment windows meet the conditions that the peak amplitude of the current window is lower than the peak amplitude of the previous window, and the fluctuation degree of the current window is less than the fluctuation degree of the previous window, or the effective pulse count is lower than the preset upper limit and remains stable, then the pressure pulsation characteristic is determined to be flat; if the above conditions are not met continuously, then the pressure pulsation characteristic is determined not to be flat. By adopting continuous window judgment and clarifying the calculation rules for the degree of fluctuation, the objective quantification of the trend judgment mechanism is realized, which can avoid the false triggering of vacuum degree recovery due to a single occasional pressure drop. The meaning of thermal stress being released is not that the welded area must be completely cooled to a state without deformation, but rather that the continuous compression of the phase change coating layer 10 by local thermal expansion has decreased to a level that allows for the re-establishment of high-rigidity support. At this point, increasing the vacuum level again will not significantly hinder the subsequent normal thermal deformation of the local area. Based on this logic, after determining that the vacuum level is approaching a plateau, the industrial control computer 18 outputs a control command to the high-frequency proportional vacuum pump 6 to restore full power, so that the secondary negative pressure intervention chamber 13 can quickly restore the ultimate vacuum level. If the vacuum level is not approaching a plateau, the reduced duty cycle is maintained, and the above acquisition, comparison and decision-making process is repeated in the next judgment window, thereby forming a closed-loop control chain of release-monitoring-recovery.

[0027] Step S1 includes: controlling the high-frequency proportional vacuum pump 6 to be in a closed state, so that the secondary negative pressure intervention chamber 13 is at normal pressure, keeping the copper-based spherical particles 14 in the secondary negative pressure intervention chamber 13 in a loose state, so that the phase change coating layer 10 exhibits compliance, filling the irregular gaps in the inner wall of the spindle motor housing, and completing the macroscopic pose construction. After S1 is completed and before the welding torch is ignited, the industrial control computer 18 controls the high-frequency proportional vacuum pump 6 to remain closed, and no negative pressure is applied in the secondary negative pressure intervention chamber 13. At this time, its interior is in a normal pressure state. The contact constraint between the copper-based spherical particles 14 in the normal pressure state is lower than the self-locking critical value, the particle group is loosely stacked, and the phase change coating layer 10 as a whole presents a conforming wall-attached state. The basic expansion bladder 7 continues to maintain the radial expansion force provided by the hydraulic pump station 5. Under the radial support, the phase change wrapping layer 10 adheres to the inner wall of the spindle motor housing and fills the small roundness error, machining lines and local irregular gaps on the inner wall. This process forms the macroscopic pose construction of the spindle motor housing relative to the positioning spindle 1, that is, the initial coaxial relationship and support relationship are established through surface contact, rather than relying on local rigid pressure to form point contact positioning; Since the high-frequency proportional vacuum pump 6 remains off during this stage, the phase change coating layer 10 will not enter the high-rigidity locking state prematurely, thereby reducing the local contact stress concentration during the clamping stage. This facilitates obtaining an inner wall fit state that meets the preset roundness tolerance, providing a stable initial contact basis for switching to the rigid support state at the moment of arc initiation.

[0028] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A multi-station synchronous welding positioning device for spindle motor housing, characterized in that, include: The positioning spindle (1) includes a central tie rod (2) with a first fluid channel (3) and a second fluid channel (4) inside. The first fluid channel (3) and the second fluid channel (4) are respectively connected to a hydraulic pump station (5) and a high-frequency proportional vacuum pump (6). The basic expansion bladder (7) is coaxially sleeved on the outside of the central tie rod (2), and its end is sealed and fixed to the central tie rod (2) and forms a primary main driving fluid cavity (8) inside. The side wall of the first fluid channel (3) is provided with a radial hole (9) that connects to the cavity (8). A phase change wrapping layer (10) is coaxially wrapped around the basic expansion bladder (7). A secondary negative pressure intervention cavity (13) filled with copper-based spherical particles (14) is formed between the inner flexible silicone film (11) and the outer flexible silicone film (12). The second fluid channel (4) is connected to the cavity (13). The counter-current corrugated compensation fluid chamber (15) is coaxially located at the end of the central tie rod (2). One end of the chamber is fixed to the central tie rod (2), and the other end is connected to an axial sliding push plate (16) that abuts against the end of the basic expansion bladder (7). Its internal cavity is connected in parallel with the first fluid channel (3) through the branch flow channel (17) in the central tie rod (2). An industrial control computer (18) controls the hydraulic pump station (5) and the high-frequency proportional vacuum pump (6), and is connected to a high-frequency pressure sensor (19) located at the inlet end of the first fluid channel (3).

2. The multi-station synchronous welding positioning device for spindle motor housing according to claim 1, characterized in that, The basic expansion capsule (7) is a cylindrical hollow structure made of fluororubber.

3. The multi-station synchronous welding positioning device for spindle motor housing according to claim 1, characterized in that, The outer diameter of the phase change coating layer (10) matches the inner diameter of the spindle motor housing to be welded.

4. The multi-station synchronous welding positioning device for spindle motor housing according to claim 1, characterized in that, The sidewall of the counter-current corrugated compensation fluid cavity (15) has a corrugated folded structure and can only undergo expansion and contraction deformation along the axial direction.

5. The multi-station synchronous welding positioning device for spindle motor housing according to claim 1, characterized in that, The second fluid channel (4) is connected to the secondary negative pressure intervention chamber (13) via a flexible conduit (20).

6. The multi-station synchronous welding positioning device for spindle motor housing according to claim 1, characterized in that, The high-frequency pressure sensor (19) collects transient pressure pulse signals in the primary main drive fluid cavity (8).

7. A method for synchronous welding and positioning of a spindle motor housing at multiple stations, applied to the synchronous welding and positioning device for a spindle motor housing at multiple stations as described in claim 1, characterized in that... include: S1. Control the hydraulic pump station (5) to inject high-pressure hydraulic oil into the first fluid channel (3) to drive the basic expansion bladder (7) to generate radial expansion force to push the phase change wrapping layer (10) to expand outward and fit against the inner wall of the spindle motor housing; S2. During the radial expansion of the basic expansion bladder (7), the high-pressure hydraulic oil enters the counter-current corrugated compensation fluid chamber (15) through the branch flow channel (17) simultaneously, driving the counter-current corrugated compensation fluid chamber (15) to generate axial elongation and pushing the axial sliding push plate (16) to apply axial thrust to the end of the basic expansion bladder (7). S3. At the moment of arc initiation when welding the spindle motor housing with a multi-station welding torch, control the high-frequency proportional vacuum pump (6) to start at full power, so that it is in full load pulse width modulation duty cycle, and evacuate the air in the secondary negative pressure intervention chamber (13), so that the phase change coating layer (10) is transformed into a rigid support state. S4. In real time, the transient pressure pulse signal in the primary main driving fluid cavity (8) collected by the high-frequency pressure sensor (19) is acquired. Within the preset observation window, the effective transient pressure pulse signal that falls within the preset frequency range and is higher than the preset amplitude is selected and integrated over time to obtain the pressure pulse integral change. S5. The pressure pulse integral change is divided by the observation window duration to convert it into the internal volume change rate of the primary main drive fluid cavity (8), and the local thermal strain rate of the spindle motor housing is calculated in reverse by combining the bulk elastic modulus of the high pressure hydraulic oil.

8. The multi-station synchronous welding and positioning method for spindle motor housing according to claim 7, characterized in that, Following step S5: When the local thermal strain rate is determined to be less than or equal to the preset elastic recovery limit threshold, the pulse width modulation duty cycle of the high-frequency proportional vacuum pump (6) is maintained to maintain the rigid support state of the phase change coating layer (10). When the local thermal strain rate is determined to be greater than the preset elastic recovery limit threshold, the pulse width modulation duty cycle of the high-frequency proportional vacuum pump (6) is reduced, the vacuum level in the secondary negative pressure intervention chamber (13) is reduced and the locking force between the copper-based spherical particles (14) is weakened, causing the phase change coating layer (10) to undergo microscopic rearrangement and relative sliding, absorbing and unloading the local thermal stress of the spindle motor housing.

9. The multi-station synchronous welding and positioning method for spindle motor housing according to claim 8, characterized in that, After determining that the local thermal strain rate is greater than the preset elastic recovery limit threshold and reducing the pulse width modulation duty cycle of the high-frequency proportional vacuum pump (6), the process further includes: Continuously acquire the transient pressure pulse signal of the high-frequency pressure sensor (19); When it is determined that the pressure pulsation characteristics of the transient pressure pulse signal tend to be flat, that is, when it is determined that within multiple consecutive judgment windows, the peak amplitude of the transient pressure pulse signal in the current judgment window is lower than the peak amplitude of the previous window, and the fluctuation degree of the current judgment window is less than the fluctuation degree of the previous window, it is determined that the local thermal stress of the spindle motor housing has been released, and the high-frequency proportional vacuum pump (6) is restored to full power output to re-establish the ultimate vacuum degree, so that the phase change wrapping layer (10) is restored to a rigid support state; When it is determined that the pressure pulsation characteristics of the transient pressure pulse signal have not become flat, that is, when the conditions for the decrease of the peak amplitude and fluctuation degree are not met, the pulse width modulation duty cycle of the reduced high-frequency proportional vacuum pump (6) is maintained.

10. The multi-station synchronous welding and positioning method for spindle motor housing according to claim 7, characterized in that, The following steps after step S1 include: The high-frequency proportional vacuum pump (6) is controlled to be in the off state, so that the secondary negative pressure intervention chamber (13) is at normal pressure, and the copper-based spherical particles (14) in the secondary negative pressure intervention chamber (13) are kept in a loose state, so that the phase change coating layer (10) exhibits compliance, fills the irregular gaps in the inner wall of the spindle motor housing, and completes the macroscopic pose construction.

Images