Stamping die and stamping method for top cover of air conditioner outdoor unit

Abstract

The invention relates to the technical field of stamping dies, and discloses an air conditioner outdoor unit top cover stamping die which comprises an upper die assembly, a lower die assembly and an ultrasonic vibration auxiliary demolding positioning pin device. The ultrasonic vibration auxiliary demolding positioning pin device comprises a positioning pin body, a vibration excitation device, a vibration transmission structure, a vibration isolation base and a control circuit. The vibration excitation device is arranged at the root of the positioning pin body, generates high-frequency mechanical vibration in the demolding stage and transmits the high-frequency mechanical vibration to the positioning pin body through the vibration transmission structure, so that the positioning pin body generates axial vibration, and continuous contact between the inner wall of a plate positioning hole and the surface of the positioning pin is converted into high-frequency intermittent contact. The equivalent friction coefficient and the contact pressure are reduced, the demolding friction force is obviously reduced, and the coating around the positioning hole of the color-coated sheet is prevented from being scratched and damaged. The control circuit achieves time sequence coordination of the vibrator and the punching action, and the vibration isolation base limits vibration within the range of the positioning pin device.

Description

Technical Field

[0001] This invention relates to the field of stamping die technology, and more specifically, to a stamping die for the top cover of an air conditioner outdoor unit. Background Technology

[0002] The top cover of an air conditioner outdoor unit is typically made of color-coated galvanized steel sheet through a stamping die. The sheet thickness is 0.5-0.8mm, and the surface is coated with a color coating of 15-25μm thickness. During the stamping process, locating pins are used to engage with pre-punched locating holes on the sheet to achieve precise positioning of the sheet relative to the die.

[0003] In existing technology, the locating pin is a static, fixed structure, made of tool steel with a chrome-plated surface, and fixed to the lower die table by threads or interference fit. The standard clearance between the locating pin and the locating hole in the sheet metal is 0.15mm, which is a clearance fit. Throughout the stamping and demolding process, the locating pin remains stationary relative to the lower die.

[0004] When stamping color-coated sheet metal, the upper die applies forming force to the sheet metal, causing a slight elastic lateral expansion of 0.2-0.3 mm under the extrusion of the upper and lower dies. This lateral expansion temporarily reduces the diameter of the positioning holes on the sheet metal, causing the inner wall of the positioning holes to press tightly against the cylindrical surface of the positioning pins. The clearance is compressed from the initial 0.15 mm to below 0.05 mm, resulting in a tight fit.

[0005] During the demolding stage, the upper mold returns and rises, lifting the sheet metal upwards under the action of the ejector device or the upper mold. The inner wall of the positioning hole slides along the cylindrical surface of the positioning pin. Since the positioning pin is completely stationary, there is static friction between the inner wall of the positioning hole and the surface of the positioning pin at the moment of demolding. The maximum static friction force must be overcome for the sheet metal to begin moving upwards. The instantaneous peak value of the maximum static friction force is most likely to cause peeling of the colored coating around the positioning hole. Throughout the upward sliding process of the sheet metal, the inner wall of the positioning hole and the surface of the positioning pin maintain continuous close contact. The accumulated friction stroke is the effective length of the positioning pin, subjecting the colored coating to continuous shear stress. This causes the colored coating within a 2-3mm range around the positioning hole to be scratched off. The area without coating protection is prone to corrosion during subsequent use, affecting the product's appearance quality and service life. Summary of the Invention

[0006] This invention provides a stamping mold for the top cover of an air conditioner outdoor unit, solving the technical problem in related technologies where scratches and damage to the colored coating around the positioning holes during the demolding process lead to easy corrosion.

[0007] This invention discloses a stamping die for an air conditioner outdoor unit top cover, including an upper die assembly, a lower die assembly, and an ultrasonic vibration-assisted demolding positioning pin device disposed on the lower die assembly. The ultrasonic vibration-assisted demolding positioning pin device includes a positioning pin body, a vibration excitation device, a vibration transmission structure, a vibration isolation base, and a control circuit. The positioning pin body is cylindrical and is used to cooperate with positioning holes on the sheet metal to achieve precise positioning of the sheet metal. The vibration excitation device is disposed at the root of the positioning pin body and is used to generate high-frequency mechanical vibration. The vibration transmission structure connects the vibration excitation device and the positioning pin body, and is used to transmit the vibration excitation device... The vibration generated is transmitted to the positioning pin body; the vibration excitation device is installed on the vibration isolation base, and the vibration isolation base is fixed on the lower mold assembly by vibration isolation pads, which is used to limit the vibration within the range of the ultrasonic vibration-assisted demolding positioning pin device; the control circuit is electrically connected to the vibration excitation device, which is used to start the vibration excitation device in the demolding stage after stamping is completed; wherein, the vibration excitation device applies high-frequency vibration to the positioning pin body in the demolding stage, so that the positioning pin body generates axial vibration, thereby changing the contact state between the inner wall of the plate positioning hole and the surface of the positioning pin body, and reducing the demolding friction.

[0008] Furthermore, the vibration excitation device is an ultrasonic vibrator, which employs a piezoelectric ceramic transducer. The ultrasonic vibrator operates at a frequency of 20-40 kHz and has an amplitude of 5-15 μm.

[0009] Furthermore, the ultrasonic vibrator adopts a Landervan transducer structure, which includes a rear cover plate, a piezoelectric ceramic stack, a front cover plate, and an amplitude transformer connected in series. The piezoelectric ceramic stack is formed by pressing multiple piezoelectric ceramic discs together with pre-tightening bolts. The amplitude transformer has a conical or stepped structure for amplifying the vibration amplitude.

[0010] Furthermore, the root of the positioning pin body is machined with a conical surface structure, which mates with the output end face of the amplitude transformer; the outer side of the conical surface at the root of the positioning pin body is provided with an external thread section, and the output end of the amplitude transformer is provided with an internal thread hole that mates with the external thread section. The conical surface at the root of the positioning pin body and the end face of the amplitude transformer are tightly fitted together by the threaded fastening connection; a coupling agent is coated between the conical surface at the root of the positioning pin body and the end face of the amplitude transformer, which is used to fill the microscopic gaps at the contact interface and improve the vibration transmission efficiency.

[0011] Furthermore, the vibration isolation base is a cylindrical structure, the vibration isolation pad is a rubber vibration isolation pad, the rubber vibration isolation pad is disposed between the bottom flange of the vibration isolation base and the platform of the lower mold assembly, the rubber vibration isolation pad is continuously distributed along the circumference of the bottom flange of the vibration isolation base, and the vibration isolation base is fixed to the lower mold assembly by bolts passing through the rubber vibration isolation pad.

[0012] Furthermore, the rubber vibration isolation pad is made of nitrile rubber material with a hardness of Shore A 60-80 degrees and a thickness of 3-5mm.

[0013] Furthermore, the control circuit includes an ultrasonic generator and a synchronous triggering unit. The ultrasonic generator is used to output a high-frequency AC signal with a frequency matching the resonant frequency of the vibration excitation device, and the output power of the ultrasonic generator is adjustable. The synchronous triggering unit is electrically connected to the control system of the stamping machine and is used to receive the position signal of the upper die. When the upper die completes the stamping stroke and begins to return to the set position, the synchronous triggering unit triggers the ultrasonic generator to start outputting. The synchronous triggering unit includes a timing control function to control the vibration excitation device to automatically shut down after working for a preset time during the demolding stage.

[0014] This invention also discloses a method for controlling the amplitude of a stamping die for an air conditioner outdoor unit top cover, applied to the aforementioned stamping die for an air conditioner outdoor unit top cover, comprising the following steps: obtaining the measured value of the sheet thickness through a laser rangefinder sensor; obtaining the coating type identifier from the production management system through a communication interface; using the measured sheet thickness and the coating type identifier as an index to query a parameter mapping table to obtain the corresponding initial values ​​of vibration frequency and amplitude; sending the initial values ​​of vibration frequency and amplitude to an ultrasonic generator; after the upper die return stroke begins, continuously collecting the axial resistance borne by the positioning pin through a piezoelectric force sensor installed at the root of the positioning pin, generating a resistance value sequence, and controlling the amplitude of the plate thickness and coating type identifier from the production management system; using the measured sheet thickness and the coating type identifier as an index to query a parameter mapping table to obtain the corresponding initial values ​​of vibration frequency and amplitude; and sending the initial values ​​of vibration frequency and amplitude to an ultrasonic generator. The resistance value sequence is used to calculate the resistance decrease rate at each moment using sliding difference calculation, and the initial maximum static friction peak value is recorded. The ratio of the current resistance value to the initial maximum static friction peak value is calculated to obtain the demolding progress index. The resistance decrease rate and the demolding progress index are input into the fuzzy control rule base, and an amplitude increment adjustment command is generated according to the fuzzy control rules. The target amplitude is calculated according to the amplitude increment adjustment command, and the target amplitude is converted into an ultrasonic generator power control command and output to the ultrasonic generator. When the resistance value in the resistance value sequence is lower than the termination threshold for 50 ms consecutively, demolding is determined to be complete, and a shutdown command is output to the ultrasonic generator.

[0015] Furthermore, the fuzzy control rule base includes the following control rules: when the resistance decrease rate is less than 0.5 N / ms, it is determined that the friction reduction effect is insufficient, and an amplitude increment adjustment command is generated, with an amplitude increment of +1 μm; when the demolding progress index is greater than 0.8, it is determined that demolding is nearing completion, and an amplitude decrease command is generated, with an amplitude increment of -1 μm; when the resistance decrease rate is greater than or equal to 0.5 N / ms and the demolding progress index is less than or equal to 0.8, it is determined that the current parameters are suitable, and an amplitude maintenance command is generated, with an amplitude increment of 0 μm.

[0016] Furthermore, the parameter mapping table is established using the following method: Demolding tests are conducted on representative sheet material samples, with sheet thicknesses covering five calibration points: 0.5mm, 0.8mm, 1.2mm, 1.5mm, and 2.0mm. Coating types include polyester coating, epoxy resin coating, and fluorocarbon coating. Vibration parameter optimization tests are performed for each thickness and coating type combination, with the vibration frequency adjusted in 2kHz steps within the 20-40kHz range and the amplitude adjusted in 1μm steps within the 5-15μm range. Ten repeated tests are performed on each set of parameters, and the vibration parameter combination with a coating integrity rate of over 95% and the shortest demolding time is selected as the calibration value for that operating condition. The calibration results are stored in the controller's non-volatile memory in the form of a two-dimensional array, forming the parameter mapping table.

[0017] This invention, by installing an ultrasonic vibrator at the root of the locating pin, applies high-frequency micro-amplitude vibration to the locating pin during the demolding stage. This transforms the continuous contact between the inner wall of the locating hole and the surface of the locating pin into a high-frequency intermittent contact, reducing the equivalent contact time and the equivalent friction coefficient to 30%-60% of the static value. Demolding friction is reduced by 60%-80%, solving the technical problem of scratch damage to the coating around the locating hole during the stamping process of color-coated steel sheets. This achieves the technical effect of increasing the integrity rate of the coating around the locating hole from 0% to over 95%, and preventing corrosion during subsequent use. The invention uses a vibration isolation base and rubber vibration isolation pads to limit vibration within the locating pin device range, achieving a vibration isolation rate of over 80%, ensuring the overall stability of the mold and the positioning accuracy of other components. The invention achieves precise timing coordination between the ultrasonic vibrator and the stamping action through a synchronous triggering unit, resulting in a high degree of automation, requiring no additional operator intervention, and not affecting the production cycle. Attached Figure Description

[0018] Figure 1 A schematic diagram of the structure of a stamping die for the top cover of an air conditioner outdoor unit. Figure 1 ;

[0019] Figure 2 A schematic diagram of the structure of a stamping die for the top cover of an air conditioner outdoor unit. Figure 2 ;

[0020] Figure 3 This is a cross-sectional view of a stamping die for the top cover of an air conditioner outdoor unit;

[0021] Figure 4 yes Figure 3 Enlarged view of point A; Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the scope of protection of the present invention.

[0023] Example 1;

[0024] This embodiment provides a stamping die for an air conditioner outdoor unit top cover. The stamping die is used to process an air conditioner outdoor unit top cover made of color-coated galvanized steel sheet. The typical structure of the air conditioner outdoor unit top cover includes a main flat part, a peripheral flange part, and multiple ventilation holes. The sheet thickness is usually 0.5-0.8mm, and the color coating thickness is 15-25μm.

[0025] During the stamping process of the air conditioner outdoor unit top cover, the precise positioning of the sheet metal 6 relative to the mold is achieved by the engagement of the positioning pin 5 with the pre-punched positioning holes on the sheet metal 6. The positioning holes of the sheet metal 6 are usually located at the four corners or the two side edges of the top cover, with a diameter of -mm. The standard clearance between the hole and the positioning pin 5 is 0.15mm, which is a clearance fit.

[0026] In the prior art, the locating pin 5 is a static fixed structure, made of tool steel and chrome-plated, and fixed to the lower die table by threads or interference fit. Throughout the stamping and demolding process, the locating pin 5 remains stationary relative to the lower die. During demolding, only the sheet metal 6 moves upward while the locating pin 5 remains stationary, resulting in a unidirectional relative movement between the two.

[0027] When stamping the color-coated sheet 6, the upper die applies a forming force to the sheet 6, generating compressive stress in the thickness direction of the sheet 6 and tensile stress in the plane of the sheet 6. Under the extrusion of the upper and lower dies, the sheet 6 undergoes a slight elastic lateral expansion. Although the expansion is only 0.2-0.3mm, the lateral expansion causes the diameter of the positioning hole on the sheet 6 to temporarily decrease, making the inner wall of the positioning hole tightly pressed against the cylindrical surface of the positioning pin 5. The fit clearance is squeezed from the initial 0.15mm to less than 0.05mm, forming a tight fit.

[0028] During the demolding stage, the upper mold returns and rises, and the sheet metal 6 is lifted upward by the ejector device or the upper mold. The inner wall of the positioning hole slides along the cylindrical surface of the positioning pin 5. The process of the inner wall of the positioning hole sliding along the cylindrical surface of the positioning pin 5 requires overcoming the frictional resistance between the inner wall of the positioning hole and the surface of the positioning pin 5. Since the positioning pin 5 is in a completely stationary state, the inner wall of the positioning hole and the surface of the positioning pin 5 are in a state of static friction at the moment of demolding. The maximum static friction force needs to be overcome to make the sheet metal 6 start to move upward. The instantaneous peak force of the maximum static friction force is most likely to cause the colored coating around the positioning hole to peel off. During the entire process of the sheet metal 6 sliding upward, the inner wall of the positioning hole and the surface of the positioning pin 5 maintain a tight surface contact. The accumulated friction stroke is the effective length of the positioning pin 5 (usually 20-30mm), which causes the colored coating to be subjected to continuous shear stress, resulting in the colored coating being scratched off within a 2-3mm range around the positioning hole. The area without coating protection is prone to corrosion in subsequent use, affecting the appearance quality and service life of the product.

[0029] like Figure 1-4 As shown, the air conditioner outdoor unit top cover stamping mold provided in this embodiment includes an upper mold assembly 1, a lower mold assembly 2, a guide mechanism, and an ultrasonic vibration-assisted demolding positioning pin 5 device.

[0030] The upper die assembly 1 includes an upper die base, an upper die plate, and a forming punch. The upper die base is driven by a lifting drive mechanism 7 to achieve up-and-down reciprocating motion. The working surface shape of the forming punch matches the inner surface shape of the air conditioner outdoor unit top cover, and is used to realize the stamping forming of the sheet metal 6.

[0031] The lower die assembly 2 includes a lower die base, a lower die plate, and a forming die. The lower die base is fixed on the press worktable. The working surface shape of the forming die matches the outer surface shape of the air conditioner outdoor unit top cover, and cooperates with the forming punch to complete the stamping process.

[0032] The guiding mechanism includes guide pillars and guide sleeves disposed between the upper and lower mold bases. The guide pillars are fixed on the lower mold base, and the guide sleeves are fixed on the upper mold base. The precise fit between the guide pillars and the guide sleeves ensures the alignment accuracy and smooth movement of the upper and lower molds.

[0033] The ultrasonic vibration-assisted demolding positioning pin 5 is a key improvement in this embodiment. It is installed on the lower template to achieve precise positioning of the sheet 6 and to provide vibration-assisted friction reduction during the demolding stage.

[0034] The ultrasonic vibration-assisted demolding positioning pin 5 device in this embodiment includes at least a positioning pin 5, a vibration excitation device 4, a vibration transmission structure, a vibration isolation base 3, and a control circuit.

[0035] The locating pin 5 retains its original locating dimensions and cylindrical shape, with an outer diameter of mm (forming a 0.15mm clearance fit with the mm locating hole in plate 6) and an effective length of 25mm. The locating pin 5 is made of Cr12MoV high-strength tool steel, and after overall quenching, its hardness reaches HRC 58-62. It is surface-plated with hard chrome, with a plating thickness of 0.01-0.02mm, to improve surface hardness and reduce the coefficient of friction. The top of the locating pin 5 is machined into an R5mm guiding arc surface to facilitate insertion into the locating hole in plate 6, and the cylindrical section provides precise radial positioning.

[0036] The vibration excitation device 4 is an ultrasonic vibrator, installed at the root of the positioning pin 5, used to generate high-frequency mechanical vibration. The ultrasonic vibrator uses a piezoelectric ceramic transducer, utilizing the inverse piezoelectric effect of piezoelectric ceramics to convert electrical energy into mechanical vibration energy.

[0037] Specifically, the ultrasonic vibrator adopts a Landervan transducer structure, which consists of a rear cover plate, a piezoelectric ceramic stack, a front cover plate, and an amplitude transformer connected in series. The rear cover plate is made of high-quality carbon steel, with a diameter of 30mm and a thickness of 10mm, and has a threaded hole in the center for connecting preload bolts. The piezoelectric ceramic stack consists of 4-8 piezoelectric ceramic discs pressed together by preload bolts. Each piezoelectric ceramic disc is 28mm in diameter and 5mm thick, made of lead zirconate titanate (PZT) piezoelectric ceramic. The polarization directions of the piezoelectric ceramic discs are arranged alternately, and electrical signals are led out between adjacent discs through copper electrode plates. The front cover plate has a similar structure to the rear cover plate and serves to preload and transmit vibration. The amplitude transformer is made of titanium alloy or aluminum alloy and has a conical or stepped structure to amplify the vibration amplitude. The amplification factor of the amplitude transformer is 2-3 times.

[0038] To obtain suitable vibration parameters for demolding friction reduction, the operating frequency of the ultrasonic vibrator is set to 20-40kHz, preferably 28kHz or 35kHz, and the amplitude is set to 5-15μm, preferably 10μm. The frequency range of 20-40kHz falls within the ultrasonic band, which is much higher than the macroscopic frequency of the demolding motion of the sheet material (demolding speed is usually 50-100mm / s, corresponding to a frequency of about 2-4Hz), and can generate high-frequency disturbances at the contact interface during demolding. The micro-amplitude vibration in the range of 5-15μm can disrupt the continuous contact state, changing the contact mode from continuous surface contact to intermittent contact, without adversely affecting the positioning accuracy and mold structure.

[0039] The vibration transmission structure is used to effectively transmit the vibration generated by the ultrasonic vibrator to the positioning pin 5. The root of the positioning pin 5 is machined into a conical surface with a cone angle of 60 degrees and a conical surface length of 8mm. The conical surface at the root of the positioning pin 5 mates with the end face of the amplitude transformer at the output end of the ultrasonic vibrator.

[0040] The vibration transmission structure employs a threaded fastening connection. The outer side of the conical surface at the base of the locating pin 5 has an M12 external thread section with a thread length of 15mm. The amplitude transformer at the output end of the ultrasonic vibrator has a matching M12 internal thread hole. During installation, the conical surface at the base of the locating pin 5 is tightened to ensure a tight fit between the threaded connection and the end face of the amplitude transformer. The tightening torque is controlled at 20-30 N·m to ensure uniform contact pressure distribution.

[0041] To improve vibration transmission efficiency and reduce energy loss, a thin layer of coupling agent is applied between the conical surface of the locating pin 5 and the end face of the amplitude transformer. The coupling agent can be high-viscosity silicone grease or epoxy resin, with a thickness controlled within the range of 0.01-0.05 mm. The coupling agent layer fills the microscopic gaps at the contact interface, eliminates air layers, improves acoustic impedance matching, and allows vibration energy to be transmitted to the locating pin 5 with minimal loss. According to acoustic tests, the vibration transmission efficiency can be improved by 15-25% after using the coupling agent.

[0042] The device also includes a vibration isolation base 3, which supports the ultrasonic vibrator and isolates and confines the vibration within the range of the ultrasonic vibration-assisted demolding positioning pin 5, preventing the vibration from being transmitted to the entire mold and causing resonance or positional drift of other components. The vibration isolation base 3 is a cylindrical structure with an outer diameter of 60mm and a height of 40mm, and is made of 45# steel. The rear cover plate of the ultrasonic vibrator is fixed to the inner cavity of the vibration isolation base 3 with M6 bolts.

[0043] The vibration isolation base 3 is fixed to the lower template platform by rubber vibration isolation pads. The rubber vibration isolation pads are placed between the bottom flange (flange outer diameter 80mm) of the vibration isolation base 3 and the lower template platform. The high damping characteristics of the rubber material can absorb the vibration energy transmitted to the bottom of the base and block the propagation path of the vibration to the lower mold.

[0044] The rubber vibration isolation pads are made of nitrile rubber (NBR) with a Shore A hardness of 60-80, preferably Shore A70, and a thickness of 3-5 mm. Rubber with a Shore A hardness range of 60-80 provides sufficient supporting stiffness to ensure positioning accuracy (axial runout of the positioning pin 5 is controlled within 0.02 mm) and good vibration absorption capacity (vibration isolation rate of over 80%). The rubber vibration isolation pads are continuously distributed circumferentially along the bottom flange of the vibration isolation base 3, forming a complete vibration isolation layer. The vibration isolation base 3 is fixed to the lower template by bolts passing through the rubber vibration isolation pads; the number of bolts is 4-6, evenly distributed circumferentially around the flange.

[0045] The device also includes a control circuit for driving the ultrasonic vibrator and coordinating its operation with the press. The control circuit includes at least an ultrasonic generator, a synchronization triggering unit, and cable connections.

[0046] The ultrasonic generator is an electronic oscillation circuit that outputs a high-frequency AC signal with a frequency matched to the resonant frequency of the ultrasonic vibrator. The ultrasonic generator employs digital frequency synthesis technology, achieving a frequency stability better than 0.1%, and the frequency can be adjusted within the range of 15-50kHz to accommodate different models of ultrasonic vibrators.

[0047] The ultrasonic generator's output power is adjustable from 50-200W, and can be adjusted via a power adjustment knob or a digital control interface (such as an RS-485 communication interface). Adjusting the output power corresponds to adjusting the vibrator amplitude, allowing for optimization of vibration parameters based on different sheet thicknesses and coating types. For example, for a thin sheet with a thickness of 0.5mm, setting the output power to 80W results in an amplitude of approximately 8μm; for a thick sheet with a thickness of 0.8mm, setting the output power to 150W results in an amplitude of approximately 12μm.

[0048] The synchronous triggering unit is electrically connected to the press control system and receives the position signal of the upper die. The press control system detects the position of the upper die through a proximity switch, photoelectric sensor, or encoder. When the upper die completes the stamping stroke and begins to return to the set position (usually the upper die rises 5-10mm), the synchronous triggering unit receives the return start signal (24V DC level signal or relay contact signal). The return start signal triggers the ultrasonic generator to start outputting, and the ultrasonic vibrator starts working and generating vibration.

[0049] To precisely control the vibration duration and avoid unnecessary energy consumption and equipment wear, the synchronous triggering unit also includes a timing control function. The ultrasonic vibrator operates for 0.2-0.5 seconds during the demolding stage, covering the entire process from the initial detachment of the sheet material 6 to its complete detachment from the positioning pin 5. Timing control is achieved through a digital timer or microcontroller. After the ultrasonic generator starts, the timer begins counting; once the set time is reached, the control circuit automatically shuts off the ultrasonic generator, the vibrator stops working, and the positioning pin 5 returns to its stationary state.

[0050] The ultrasonic generator is connected to the electrodes of the ultrasonic vibrator via a cable. The cable is a double-shielded cable (inner layer is braided shielding, outer layer is aluminum foil shielding), with a conductor cross-sectional area of ​​1.5 mm², to prevent electromagnetic interference from high-frequency electrical signals to surrounding equipment. The cable is routed through a pre-reserved cable tray inside the lower mold to avoid interference with other moving parts, and the cable length is controlled within 2m to reduce transmission loss.

[0051] To effectively reduce demolding friction through vibration, the geometry and material properties of the locating pin 5 were optimized so that ultrasonic vibration primarily propagates along the axial direction of the locating pin 5. The length-to-diameter ratio (length / diameter) of the locating pin 5 was designed to be 2.5. This ratio ensures that the locating pin 5 primarily generates axial vibration modes under ultrasonic excitation, suppressing radial and bending vibration modes.

[0052] After the vibration is input from the root of the locating pin 5, it propagates along the axial direction of the locating pin 5 in the form of a longitudinal wave to the top. The propagation speed of the longitudinal wave in the locating pin 5 is about 5000 m / s (depending on the material density and elastic modulus). A small axial vibration is generated on the cylindrical surface of the locating pin 5, and the vibration amplitude is basically uniformly distributed along the axial direction. The amplitude attenuation in the middle and top of the locating pin 5 is less than 10%.

[0053] Axial vibration causes the surface of the locating pin 5 to generate high-frequency reciprocating motion in the axial sliding direction of the plate 6 during demolding. The motion frequency is consistent with the ultrasonic frequency (20-40kHz), and the amplitude is 5-15μm. This creates a periodic superposition of relative motions at the contact interface, disrupting the continuous contact between the inner wall of the locating hole and the surface of the locating pin 5.

[0054] The working process of the air conditioner outdoor unit top cover stamping mold in this embodiment includes four stages: plate positioning, stamping, ultrasonic vibration start-up, and vibration-assisted demolding.

[0055] The board material has six positioning stages;

[0056] The operator places a pre-punched color-coated sheet 6 (600mm × 400mm × 0.6mm, made of HDP color-coated galvanized steel sheet) with pre-punched positioning holes on the workbench of the lower template. The positioning holes (diameter mm, located at the four corners of sheet 6, 30mm from the edge) are aligned with the cylindrical section of the positioning pin 5. Under the weight of sheet 6 or downward pressure applied by the operator, the positioning holes fit into the positioning pin 5. The R5mm guiding arc surface at the top of the positioning pin 5 acts as a guide, ensuring smooth insertion of the positioning holes. The inner wall of the positioning hole and the cylindrical surface of the positioning pin 5 form a clearance fit of 0.15mm, achieving precise positioning of sheet 6 relative to the mold, with a positioning accuracy of ±0.05mm. At this time, the ultrasonic generator in the control circuit is off, and the positioning pin 5 remains stationary.

[0057] Stamping stage;

[0058] The press is started, and the upper die moves downward at a speed of 30-50 mm / s under the drive of the press slide. The working surface of the forming punch of the upper die first contacts the upper surface of the sheet metal 6, and then continues to press down. The sheet metal 6 is subjected to extrusion force between the upper forming punch and the lower forming die, with the peak extrusion force reaching 200-300 kN (depending on the complexity of the top cover and the thickness of the sheet metal 6). The sheet metal 6 undergoes elastoplastic deformation, forming the design shape of the air conditioner outdoor unit top cover, including the slight curved surfaces of the main planar part, the downward flange around the perimeter (flange height 15 mm, flange angle 90 degrees), and ventilation holes (hole diameter mm, number 30-50).

[0059] During the extrusion process, the extrusion force on sheet 6 generates compressive stress (approximately 300-400 MPa) in the thickness direction of sheet 6, and simultaneously generates tensile stress (approximately 50-80 MPa) in the plane of sheet 6. The tensile stress component causes sheet 6 to expand laterally. The lateral expansion of sheet 6 is 0.2-0.3 mm, temporarily reducing the diameter of the positioning hole by approximately 0.1-0.15 mm. The inner wall of the positioning hole exerts radial extrusion on the cylindrical surface of the positioning pin 5, reducing the clearance between the positioning hole and the positioning pin 5 from the initial 0.15 mm to below 0.05 mm, and even forming an interference fit in some local areas. The inner wall of the positioning hole and the surface of the positioning pin 5 form a tight contact, with a contact pressure reaching 5-10 MPa. The entire stamping process lasts approximately 0.5-1.0 seconds, during which the ultrasonic vibrator remains off, and the positioning pin 5 remains stationary, providing a stable positioning reference to ensure stamping accuracy.

[0060] Ultrasonic vibration initiation stage;

[0061] After stamping is completed, the upper die stops pressing down and begins its return upward movement. When the upper die rises to a position 5-10mm away from the lower die surface, the press control system detects the upper die position via a proximity switch and outputs a return start signal (24V DC level signal). This return start signal is transmitted via electrical circuitry to the synchronization trigger unit of the ultrasonic vibration-assisted demolding positioning pin 5 device. After receiving the return signal, the synchronization trigger unit, after a processing delay of approximately 0.05 seconds, triggers the ultrasonic generator to start operating.

[0062] The ultrasonic generator's oscillation circuit initially outputs a high-frequency AC signal with a frequency of 28kHz, a voltage amplitude of 200-400V, and a power of 120W. This high-frequency AC signal is transmitted to the piezoelectric ceramic electrodes of the ultrasonic vibrator via a shielded cable.

[0063] Under the influence of an alternating electric field, piezoelectric ceramics exhibit the inverse piezoelectric effect, producing periodic expansion and contraction along the polarization direction. The expansion and contraction of each piezoelectric ceramic disc is approximately 2-3 μm, and the frequency of this periodic expansion and contraction is consistent with the input electrical signal frequency (28 kHz). The expansion and contraction deformations of six piezoelectric ceramic discs are superimposed and output as mechanical vibration through a front cover plate and an amplitude transformer. The conical structure of the amplitude transformer amplifies the vibration amplitude by a factor of 2.5, resulting in an output vibration amplitude of 10 μm. The vibration is transmitted to the positioning pin 5 via a conical connection at its root, with a coupling agent layer ensuring a vibration transmission efficiency of over 85%. Under ultrasonic excitation, the positioning pin 5 generates high-frequency micro-vibrations along the axial direction with a frequency of 28 kHz and an amplitude of 10 μm. The time from vibration initiation to reaching a stable amplitude is approximately 0.02 seconds.

[0064] Vibration-assisted demolding stage;

[0065] During the demolding stage, the upper mold continues to move upward. The ejection device of the upper mold (such as an ejector pin or air cushion) or the friction between the upper mold and the sheet 6 drives the sheet 6 upward at a speed of 50-100 mm / s. The sheet 6 detaches from the forming cavity surface of the lower mold. During the upward movement of the sheet 6, the positioning hole needs to disengage from the positioning pin 5, and the inner wall of the positioning hole slides upward relative to the surface of the positioning pin 5. At this time, the positioning pin 5 is in a high-frequency vibration state, and the inner wall of the positioning hole is in contact with the vibrating surface of the positioning pin 5.

[0066] High-frequency vibration changes the contact state between the inner wall of the positioning hole and the surface of the positioning pin 5 from continuous contact to intermittent high-frequency contact. In each vibration cycle (cycle time 1 / 28000 s ≈ 36 μs), the surface of the positioning pin 5 reciprocates in the axial direction with an amplitude of 10 μm. When the surface of the positioning pin 5 moves upward (occupying half a cycle, approximately 18 μs), it contacts the inner wall of the positioning hole and generates contact pressure. When the surface of the positioning pin 5 moves downward (occupying the other half of the cycle, approximately 18 μs), it separates from the inner wall of the positioning hole or the contact pressure decreases. The actual contact time between the surface of the positioning pin 5 and the inner wall of the positioning hole accounts for only 40%-60% of the time in one vibration cycle. The reduced equivalent contact time lowers the average contact pressure to 50-70% of the static contact pressure.

[0067] According to the mechanism of vibration-induced friction reduction, high-frequency vibration reduces the equivalent friction coefficient of the contact interface. Macroscopically, the frictional resistance F that the plate 6 needs to overcome to move upwards is equal to the product of the equivalent friction coefficient and the average contact pressure N, i.e., F = 0.05-0.12. Because high-frequency vibration reduces the equivalent friction coefficient to 30%-60% of the static sliding friction coefficient s (typically 0.15-0.20), i.e., the equivalent friction coefficient = 0.05-0.12, and simultaneously reduces the average contact pressure N, the frictional resistance F is significantly reduced, by 60-80%.

[0068] Meanwhile, the microscopic slippage generated at the contact interface by ultrasonic vibration avoids viscous friction between the inner wall of the positioning hole and the surface of the positioning pin 5, making the transition from static friction to dynamic friction smoother and eliminating the frictional peak at the moment of demolding start. In the absence of vibration, the frictional peak at the moment of demolding start can reach 2-3 times the average frictional force, while in the vibration-assisted state, the difference between the frictional peak and the average frictional force is reduced to less than 10%.

[0069] Under reduced frictional resistance, plate 6 moves smoothly upwards, and the positioning hole slides along the cylindrical surface of positioning pin 5 until it completely disengages from the top of positioning pin 5. The demolding stroke is 25mm (equal to the effective length of positioning pin 5), and the demolding time is approximately 0.3 seconds. After demolding, the timer in the synchronous trigger unit reaches the set time of 0.4 seconds (starting from the start of the vibrator), and the control circuit shuts off the output of the ultrasonic generator. The ultrasonic vibrator stops working, and positioning pin 5 returns to a stationary state.

[0070] The shear stress borne by the colored coating around the positioning hole on the plate 6 during demolding is approximately 5-10 MPa, which is lower than the bonding strength between the colored coating and the substrate (typically 15-25 MPa). The colored coating remains intact without peeling damage. Testing showed that after using the ultrasonic vibration-assisted demolding positioning pin 5 device of this embodiment, the integrity rate of the colored coating within a 3mm radius around the positioning hole increased from 0% to over 95%.

[0071] In some embodiments, to adapt to the processing requirements of different thicknesses of sheet material 6 or different types of colored coatings, the vibration parameters are optimized by adjusting the output power of the ultrasonic generator before operation. For cases where sheet material 6 is thicker (e.g., 0.8 mm) or the stamping deformation is large, the output power is increased to 180 W so that the vibration amplitude is close to the upper limit of 15 μm, providing a stronger friction reduction effect; for cases where sheet material 6 is thinner (e.g., 0.5 mm) or the coating adhesion is strong, the output power is reduced to 60 W so that the vibration amplitude is close to the lower limit of 5 μm, which meets the friction reduction requirements while avoiding excessive amplitude from causing additional impact on the coating.

[0072] In other embodiments, to further improve the demolding effect, a thin lubricating coating is applied to the cylindrical surface of the locating pin 5. The lubricating coating is a solid lubricant, using molybdenum disulfide (MoS2) or polytetrafluoroethylene (PTFE) material, and is applied to the chromium-plated surface via spraying or dipping processes. The coating thickness is 0.005-0.01 mm. The coefficient of friction of the lubricating coating is approximately 0.05-0.10. Under the synergistic effect of ultrasonic vibration, the coefficient of friction between the inner wall of the locating hole and the surface of the locating pin 5 is further reduced to 0.03-0.08. The combined effect of these two friction-reducing mechanisms produces a superior demolding effect, with the integrity rate of the colored coating reaching over 98%.

[0073] In some embodiments, the number of ultrasonic vibration-assisted demolding positioning pins 5 is determined according to the size and shape of the air conditioner outdoor unit's top cover. For smaller top covers (e.g., 400mm × 300mm), two ultrasonic vibration-assisted demolding positioning pins 5 are provided, located diagonally opposite each other; for larger top covers (e.g., 800mm × 600mm), four ultrasonic vibration-assisted demolding positioning pins 5 are provided, located at the four corners. The ultrasonic vibrators of multiple ultrasonic vibration-assisted demolding positioning pins 5 are driven by the same ultrasonic generator to ensure consistency in vibration frequency and phase.

[0074] This embodiment uses an ultrasonic vibrator installed at the root of the positioning pin 5 to apply high-frequency, low-amplitude vibration to the positioning pin 5 during the demolding stage, thereby altering the contact dynamics between the inner wall of the positioning hole and the surface of the positioning pin 5. According to the principle of ultrasonic vibration friction reduction, when the vibration frequency is much higher than the macroscopic motion frequency and the amplitude is appropriate, the contact interface experiences periodic separation and contact, transforming the originally continuous surface contact into high-frequency intermittent contact, reducing the average contact time and the equivalent contact pressure. According to the friction calculation formula, friction is equal to the product of the normal force and the coefficient of friction; the reduction in average contact pressure directly leads to a decrease in friction.

[0075] Meanwhile, the micro-oscillations generated at the contact interface by high-frequency vibration disrupt the conditions for adhesive friction. In the absence of vibration, static friction occurs between the inner wall of the positioning hole and the surface of the positioning pin 5 at the moment of demolding, requiring the overcoming of maximum static friction force. The instantaneous peak value of this maximum static friction force is the main factor causing coating peeling. High-frequency vibration keeps the contact interface in a state of constant micro-motion, preventing a completely static contact state and making the transition from static to dynamic friction smoother, eliminating the high friction peak value at the moment of start-up. Therefore, it overcomes the high static friction force and continuous shear stress generated by continuous contact between the positioning hole and the positioning pin 5 in a static state, solving the problem of scratch damage to the colored coating.

[0076] Furthermore, the mechanism of ultrasonic vibration-assisted demolding changes the contact characteristics of the friction pair through physical vibration, rather than altering the material or geometry. Therefore, it does not affect the positioning accuracy and function of the locating pin 5. During the stamping stage, the vibrator is turned off, and the locating pin 5 remains stationary, providing a stable positioning reference and ensuring the positional accuracy of the sheet 6 relative to the mold. During the demolding stage, the vibrator is activated, providing friction reduction only during the time period when the sheet 6 needs to detach from the locating pin 5. The vibration duration is controlled within 0.2-0.5 seconds, covering the entire demolding process while avoiding unnecessary energy consumption and equipment wear.

[0077] The ultrasonic vibration-assisted demolding positioning pin 5 device achieves precise coordination between the ultrasonic vibrator and the punch press through a synchronous triggering unit. It boasts a high degree of automation, requires no additional operator intervention, and does not affect the production cycle. The vibration isolation base 3 and rubber vibration isolation pads confine vibration within the range of the ultrasonic vibration-assisted demolding positioning pin 5 device, preventing vibration from being transmitted to other parts of the mold and ensuring the overall stability of the mold and the positioning accuracy of other components.

[0078] After implementing this technical solution, the coating around the positioning holes is completely preserved during the demolding process of the color-coated sheet 6. The coating damage rate is reduced from 100% (coating scratches will inevitably occur around the positioning holes) to close to 0. The product appearance quality is significantly improved, and the corrosion problem in the area around the positioning holes is avoided in subsequent use, thus extending the product's service life.

[0079] Example 2;

[0080] This embodiment provides an adaptive control method for ultrasonic vibration parameters based on demolding resistance feedback. The adaptive control method for ultrasonic vibration parameters based on demolding resistance feedback is applied to a stamping system equipped with an ultrasonic vibration-assisted demolding positioning pin 5 device.

[0081] In the production of stamped products such as the top cover of air conditioner outdoor units made of color-coated sheet metal, ultrasonic vibration-assisted demolding technology is used to reduce the demolding friction between the positioning pin 5 and the positioning hole of the sheet metal 6, thus protecting the surface coating of the sheet metal 6. Existing ultrasonic vibration-assisted demolding systems use a fixed vibration parameter control method, with the ultrasonic generator outputting a fixed frequency (e.g., ...). kHz) and fixed amplitude (such as The excitation signal (μm) is used to start the vibrator at the beginning of the upper mold return stroke, and the working time is preset (e.g., μm). The vibration parameter remains constant throughout the demolding process, closing after (seconds). The fixed vibration parameter control method is based on time-triggered open-loop control logic, which does not detect differences in the six characteristics of the sheet material or monitor the demolding process status.

[0082] In actual production, the thickness of sheet 6 varies between batches and individual pieces, with a thickness range of [missing information]. - The tightness of the compression between the positioning hole and the positioning pin 5 varies depending on the thickness of the sheet material 6 under the same punching pressure. The lateral expansion of the thin plate is approximately mm. mm, the extrusion pressure is relatively small, while the thickness is... The lateral expansion of a thick plate of mm can reach The extrusion pressure increased significantly with mm, resulting in a marked difference in demolding resistance. Meanwhile, the surface coatings on sheet 6 included various materials such as polyester coating and epoxy resin coating. Different coating materials had different coefficients of friction; the coefficient of friction for the polyester coating was approximately [missing value]. The coefficient of friction of the epoxy resin coating is approximately Differences in coating type further affect the demolding friction characteristics. Furthermore, the degree of stamping deformation varies due to differences in die geometry at different locations on the sheet metal 6, with variations reaching up to [missing information]. - This results in uneven distribution of deformation of the positioning holes and demolding resistance.

[0083] Fixed vibration parameters cannot adapt to the aforementioned changes in operating conditions. When considering thickness... Thin plates of mm use amplitude During large-amplitude vibrations of μm, due to the low stiffness of the thin plate, the vibration energy is easily transmitted to the plate body 6 through the locating pin 5, causing additional vibration of the plate 6 as a whole. This additional vibration of the plate 6 results in secondary bending deformation during the stage when the plate 6 has completed plastic forming but has not yet fully solidified, affecting the dimensional accuracy of the forming. When considering the thickness... mm thick plate using amplitude During small-amplitude vibration (μm), due to the large compressive force between the thick plate and the locating pin 5, the vibration energy generated by the small-amplitude vibration is insufficient to effectively penetrate the tight contact interface. The intermittent contact between the inner wall of the locating hole and the surface of the locating pin 5 is not significant, and the equivalent friction coefficient of the contact interface only decreases to a fraction of the static sliding friction coefficient. The demolding resistance remains high, the shear stress borne by the coating is close to its critical bond strength value, and the risk of scratching still exists.

[0084] The essence of the technical problem that fixed vibration parameters cannot adapt to the above-mentioned changes in working conditions lies in the mismatch between the open-loop control method of fixed parameters and the variable working conditions. Fixed vibration parameters are only suitable for a certain thickness, a certain coating and a certain degree of deformation of the plate 6. When the characteristics or processing state of the plate 6 deviate from the specific working conditions, the demolding and friction reduction effect decreases, resulting in the inability to simultaneously guarantee the forming accuracy of thin plates and the coating protection of thick plates.

[0085] According to the implementation method of this embodiment, the hardware environment of the ultrasonic vibration parameter adaptive control method based on demolding resistance feedback includes: a stamping machine, upper and lower mold assemblies, an ultrasonic vibration-assisted demolding positioning pin 5 device, a laser rangefinder sensor installed at the beginning of the upper mold return stroke, a piezoelectric force sensor installed at the root of the positioning pin 5, an ultrasonic generator, a controller, and corresponding signal acquisition and processing circuits. The controller is connected to the production management system through a data communication interface to receive production batch information.

[0086] Step 100: Obtain the 6 characteristic data of the plate material and generate initial vibration parameters.

[0087] Step 101: Obtain the measured thickness of plate 6. When the upper die is in the return start position, the laser rangefinder installed at the upper die return start position emits a laser beam downwards. The laser beam illuminates the upper surface of plate 6 located on the lower die table. The laser rangefinder receives the reflected laser signal and calculates the distance from the sensor to the upper surface of plate 6 based on the laser flight time. This distance value is subtracted from the pre-calibrated reference distance from the sensor to the lower die table to obtain the measured thickness of plate 6. The measurement accuracy is mm, sampling frequency is Hz, taking continuous The average of the measurements was used as the final measured thickness of the plate.

[0088] Step 102: Obtain the coating type identifier. The controller receives the coating type code of the current production batch from the production management system via the RS-485 communication interface. The coating type is encoded as an integer value, with the following encoding rules: polyester coating corresponds to code 1, epoxy resin coating corresponds to code 2, and fluorocarbon coating corresponds to code 3. The communication data format is a standard Modbus protocol frame, and the receive timeout is set to... Second.

[0089] Step 103: Calculate the initial vibration parameters. The controller will display the measured thickness of plate 6. and coating type coding As an index, the parameter mapping table stored in the controller's non-volatile memory is queried to obtain the corresponding initial value of the vibration frequency. and initial value of amplitude The parameter mapping table stores the empirically optimal vibration parameters corresponding to different combinations of plate thickness ranges and coating types.

[0090] Furthermore, the above parameter mapping table was established using the following method: Before the system was put into use, a demolding test was conducted on 6 representative board samples, with the thickness of board 6 covering... mm mm mm mm Five calibration points were used, and the coating types included polyester coating, epoxy resin coating, and fluorocarbon coating. Vibration parameter optimization tests were conducted for each combination of thickness and coating type, with vibration frequencies ranging from [insert frequency range here]. - In the kHz range kHz step size adjustment, amplitude in - Within μm range μm step size adjustment, for each set of parameters The experiment was repeated several times, and the coating condition around the positioning hole was observed using a high-speed camera system. The experiment was conducted when the coating integrity rate reached a certain level. The vibration parameter combination with a percentage of % or higher and the shortest demolding time is used as the calibration value for the combination of plate thickness and coating type. The calibration results are stored in the controller's non-volatile memory in the form of a two-dimensional array to form a parameter mapping table.

[0091] It should be noted that the above parameter mapping table lookup process uses a piecewise linear interpolation method. When the actual measured thickness of the plate is 6... Located at two adjacent thickness calibration points and During the interval, the initial amplitude Calculate using the following formula:

[0092]

[0093] in, and These are the thickness calibration points in the parameter mapping table. and The corresponding calibrated amplitude value; The measured thickness of the sheet material is 6 mm; initial frequency. Coding based on coating type The initial vibration parameters are obtained directly from the table without interpolation. and The data is sent to an ultrasonic generator, which sets the output frequency and power based on the received parameters.

[0094] Step 200: Obtain real-time data on demolding resistance and calculate resistance characteristic indicators.

[0095] Step 201: Obtain the demolding resistance numerical sequence. After the upper mold return stroke begins, the piezoelectric force sensor installed at the root of the positioning pin 5 continuously collects the axial resistance borne by the positioning pin 5. The measurement range of the force sensor is... - N, sensitivity is mV / N, sampling frequency set to The signal acquisition circuit amplifies and converts the analog voltage signal output by the force sensor to digital, with a generation time interval of kHz. resistance numerical sequence of ms The sequence data is transmitted to the controller's data buffer in real time.

[0096] Furthermore, the length of the aforementioned resistance numerical sequence The duration of the actual demolding process is determined by the force sensor throughout the entire process, from the start of the upper mold return stroke to the completion of demolding. Continuous sampling at a kHz sampling frequency, if the demodulation time is Seconds, then the sequence length Under normal working conditions, the demolding time is usually [time period missing]. - seconds, corresponding sequence length for - There are 1 data points, and the controller's data buffer capacity is set to 1. One data point is sufficient to accommodate the longest Data on the demolding process in seconds.

[0097] Step 202: Calculate the rate of change of resistance. The controller applies a time window to the resistance numerical sequence. The sliding difference operation in milliseconds calculates the value at each time step. rate of decrease in resistance The calculation formula is:

[0098]

[0099] in, and They are time points and The corresponding resistance value, ms is the sampling time interval; time. Indicates the number of times since demolding begins. The calculation formula is: [Sampling time] ms, where The range of values ​​is arrive (forward (The rate of change for each data point does not need to be calculated due to the difference operation); when... The value indicates that the resistance is decreasing; the larger the value, the faster the resistance is decreasing. If the resistance does not decrease or increases, it is determined that the friction reduction effect is insufficient.

[0100] Step 203: Calculate the demolding progress index. The controller records the maximum value in the resistance value sequence at the instant of demolding start. As the initial peak value of the maximum static friction force, for each moment Calculate the current resistance value Peak value of initial maximum static friction The ratio of is defined as the demolding progress index. :

[0101]

[0102] Among them, demolding progress indicators The range of values ​​is arrive , This indicates that demolding has just begun, and the resistance is at its maximum. near This indicates that the resistance has been reduced to near zero, and demolding is about to be completed.

[0103] Step 300: Generate vibration parameter adjustment instructions and execute dynamic control.

[0104] Step 301: Generate parameter adjustment instructions; the controller will adjust the current resistance descent rate. Demolding progress indicators Input the following control rules into the fuzzy control rule base, which contains the following control rules:

[0105] Rule 1: When the resistance decreases at a certain rate When the amplitude is N / ms, the friction reduction effect is deemed insufficient, and an amplitude increment adjustment command is generated. μm;

[0106] Rule 2: When the demolding progress indicator When the demolding process is nearing completion, an amplitude decrease command is generated, and the amplitude increment... μm;

[0107] Rule 3: When N / ms and When the current parameters are deemed suitable, an amplitude maintenance command is generated, and the amplitude increment is... μm.

[0108] Furthermore, the resistance descent rate threshold in Rule 1 above... N / ms is determined based on the typical time characteristics of the demolding process. During normal demolding, the time for sheet 6 to completely detach from the locating pin 5 is approximately seconds, the effective length of positioning pin 5 is mm, the initial maximum static friction peak value is usually - N, if the rate of decrease in resistance is lower than N / ms, then Insufficient decrease in resistance within seconds N, cannot guarantee a smooth demolding process, therefore N / ms is used as the critical value for determining whether the friction reduction effect is sufficient. The demolding progress threshold in Rule 2... This indicates that the current resistance has decreased to the initial peak value of the maximum static friction force. Below 5%, the contact pressure between plate 6 and locating pin 5 has decreased significantly. Continuing to maintain large-amplitude vibration would cause unnecessary impact on plate 6. Therefore, This serves as a critical value for determining whether the demolding process has entered its final stage.

[0109] The decision period for the fuzzy control rule base is ms, every time ms performs a rule matching and instruction generation.

[0110] Step 302: Perform dynamic adjustment of vibration parameters. The controller adjusts the parameters according to the amplitude increment. Calculate the target amplitude :

[0111]

[0112] in, Given the current actual amplitude value, the controller adjusts the target amplitude. Amplitude limiting is applied to ensure that it remains within the initial amplitude. of Within % range:

[0113]

[0114] Furthermore, the aforementioned limit range The percentage setting takes into account the safety and effectiveness of vibration parameter adjustment, initial amplitude This is an empirically optimal value determined using a parameter mapping table based on the thickness of the sheet material and the coating type. If the amplitude is lower after adjustment... The vibration energy is insufficient to effectively disrupt the continuous contact between the positioning hole and the positioning pin 5, resulting in a significant decrease in the friction reduction effect; if the adjusted amplitude is higher than... Excessive vibration energy may be transmitted to the sheet material 6 itself, causing overall vibration of the sheet material 6 and affecting molding accuracy. Therefore, the dynamic adjustment range is limited to the initial amplitude. arrive Between times.

[0115] The controller will target amplitude Converted into power control commands for the ultrasonic generator, and output via a digital-to-analog converter. - The analog control voltage signal V is sent to the power control module of the ultrasonic generator, which adjusts the output power of the ultrasonic generator so that the amplitude response time of the vibrator does not exceed V. ms.

[0116] Step 400: Determine the demolding completion conditions and output a control signal.

[0117] When the resistance value sequence is continuous The resistance values ​​of ms are all below the termination threshold. When N is reached, the controller determines that demolding is complete, generates a demolding completion signal, and outputs a shutdown command to the ultrasonic generator. The ultrasonic generator stops outputting and the vibrator stops working.

[0118] Furthermore, the aforementioned termination threshold N is determined based on the residual friction force when plate 6 and locating pin 5 are completely separated. When the locating hole of plate 6 is about to completely disengage from the top of locating pin 5, the contact area decreases to a fraction of the cross-sectional area of ​​locating pin 5. Below %, even without ultrasonic vibration, the residual friction force is only [amount missing]. - N will not damage the color coating, therefore... N serves as the critical resistance value for determining whether demolding is complete. When the resistance remains below this value, it indicates that sheet metal 6 has essentially disengaged from locating pin 5. The millisecond time-based judgment condition is used to avoid misjudgments caused by instantaneous fluctuations in the resistance signal and to ensure the reliability of the demolding judgment.

[0119] The controller records the measured thickness of the sheet metal during this demolding cycle. Coating type coding Initial vibration parameters and Final vibration parameters and Demolding time The statistical characteristics of the resistance numerical sequence are stored in a database in CSV text file format for subsequent optimization of parameter mapping tables and fault diagnosis analysis.

[0120] In this embodiment, to further improve the response speed and control accuracy of parameter adjustment, a hybrid control strategy combining fuzzy control and proportional-derivative control is adopted when generating the parameter adjustment command in step 301. Based on the fuzzy control rules in step 301, a proportional control component based on resistance deviation and a derivative control component based on the resistance change rate are added.

[0121] Specifically, within each determination cycle, the controller first determines the current demolding progress index. Calculate the expected resistance value :

[0122]

[0123] Among them, coefficient The friction reduction target coefficient, set empirically, represents the desired reduction of the resistance at the current stage to the initial peak value of the maximum static friction. %.

[0124] Furthermore, the aforementioned expected resistance value It is a time-varying objective function, whose time evolution characteristics are determined by the demolding progress index. Decision. In the initial stage of demolding ( near (ms) Demolding progress index Expected resistance value The goal is to quickly reduce the resistance to its initial value. %; as the demolding process progresses, the demolding progress indicators Gradually increase, expected resistance value It then decreases linearly, when When (halfway through demolding), the expected resistance value decreases to When nearing the completion of demolding ( The expected resistance value is reduced to The objective function, which changes dynamically over time, enables the control system to maintain an appropriate friction-reducing force throughout the demolding process. This avoids excessive resistance in the early stages of demolding, which could damage the coating, and also prevents excessive vibration in the later stages of demolding from affecting the precision of the sheet material.

[0125] Furthermore, the target coefficient for the aforementioned friction reduction effect... The bonding strength between the color coating and the substrate is determined based on the adhesion strength of the color coating. - MPa, the coating area around the positioning hole subjected to shear stress is approximately mm², the maximum shear force that the coating can withstand is approximately - N, the initial maximum static friction peak value is usually - N, if the desired resistance value is set too high (e.g., the coefficient is greater than N), Corresponding expected resistance If the cumulative shear stress on the coating during demolding is above N, approaching its bonding strength, there is still a risk of coating peeling. If the desired resistance value is set too low (e.g., the coefficient is less than N), further damage may occur. Corresponding expected resistance (below N), requiring excessively large amplitudes to achieve the desired effect, which could cause overall vibration of the plate 6. Therefore, the target coefficient for the friction reduction effect is set to [value missing]. This allows for rapid demolding while ensuring coating safety.

[0126] Then calculate the drag deviation. :

[0127]

[0128] The controller calculates the amplitude adjustment amount. :

[0129]

[0130] in, This is the proportional gain coefficient, and its value range is... - μm / N, The differential gain coefficient has a range of values ​​of 1000. - μm / (N / ms); Amplitude adjustment amount After amplitude limiting, the amplitude increment is used, and the amplitude increment for a single adjustment is limited to [a certain value]. μm to Within the μm range.

[0131] Furthermore, the aforementioned proportional gain coefficient and differential gain coefficient The specific value is determined based on the thickness of the sheet material (6). For thicknesses less than 6, the value will be determined based on the thickness of the sheet material (6). The thin plate (mm) has low stiffness and is sensitive to amplitude changes. (Setting...) μm / N, μm / (N / ms), using a small gain coefficient ensures stable control; for thickness - Medium-thickness plate of mm, set μm / N, μm / (N / ms), using a medium gain coefficient to balance response speed and stability; for thicknesses greater than The plate is 6 mm thick, has high rigidity, and has high demolding resistance. (Setting...) μm / N, μm / (N / ms), a larger gain coefficient is used to improve the control response speed. After the controller obtains the measured thickness value of plate 6 in step 101, it automatically selects the corresponding gain coefficient value according to the thickness range.

[0132] Furthermore, the aforementioned single adjustment restrictions μm is determined based on the response characteristics and control stability requirements of the ultrasonic vibrator. The amplitude response time of the ultrasonic vibrator is approximately... ms, if the single adjustment amount is too large (exceeding) Rapid changes in amplitude (μm) can cause instability in the vibrator output, resulting in amplitude overshoot and oscillation, affecting the smoothness of the demolding process; if the single adjustment amount is too small (below μm), the vibration will be unstable. If the resistance is less than μm, it cannot respond to changes in resistance in a timely manner, and the adjustment effect is not obvious. Therefore, the single adjustment limit is set to μm. μm, ensuring controllable response speed while avoiding drastic amplitude fluctuations.

[0133] The hybrid control strategy combining fuzzy control and proportional-derivative control allows vibration parameter adjustment to consider both the magnitude of the resistance deviation and the trend of resistance change, thereby improving the dynamic response performance and anti-disturbance capability of the control system.

[0134] In this embodiment, to adapt to changes in the characteristic distribution of the sheet material 6 during long-term production, a self-learning mechanism of the parameter mapping table is used to optimize the parameter mapping table when calculating the initial vibration parameters in step 103. The controller periodically (e.g., after each production run) optimizes the parameter mapping table. After the product is completed, historical demolding data is read from the database. For each sheet material with 6 thickness ranges and coating type combinations, the corresponding final average amplitude is calculated. and average demolding time .

[0135] When the number of historical data samples for a certain working condition combination exceeds At any given time, the controller calculates the optimal amplitude value for that operating condition. :

[0136]

[0137] in, This refers to the current calibrated amplitude value for this operating condition in the parameter mapping table. The final average amplitude calculated from historical data, with weighting coefficients. and This reflects a comprehensive consideration of existing empirical parameters and actual operating data; the controller optimizes the amplitude value. Update the parameter mapping table, replacing the original calibration amplitude values. The self-learning mechanism of the parameter mapping table enables it to gradually adapt to the statistical distribution of the six characteristics of the sheet metal in actual production, thereby improving the accuracy of initial vibration parameter settings and reducing parameter deviations and adjustment times during dynamic control.

[0138] This implementation acquires characteristic data of the sheet material 6 and demolding process status data through multi-sensor fusion. It uses a parameter mapping table to calculate initial vibration parameters based on the measured thickness of the sheet material 6 and the coating type identifier, achieving differentiated initial parameter settings and overcoming the incompatibility of fixed parameters with different sheet material 6 characteristics and operating conditions. Regarding thickness... For thin plates of mm, the parameter mapping table outputs a small initial amplitude (e.g., ...). (μm), to avoid large-amplitude vibration energy being transferred to the plate 6 and causing secondary bending deformation; for thickness For a plate with a thickness of mm, the parameter mapping table outputs a larger initial amplitude (e.g., ...). The vibration energy (μm) is sufficient to penetrate the tightly contacted interface to produce an effective friction reduction effect. This differentiated initial parameter setting mechanism ensures that the vibration parameters are in a near-optimal state at the start of demolding, reducing the adjustment range of subsequent dynamic control.

[0139] Furthermore, this embodiment uses a piezoelectric force sensor to collect demolding resistance data in real time, calculates two characteristic indicators: the resistance reduction rate and the demolding progress index, and introduces the dynamic information of the demolding process into the control loop to form a closed-loop control system. When the resistance reduction rate is lower than a threshold, the fuzzy control rule base determines that the current amplitude produces insufficient friction reduction effect, outputs an amplitude increment adjustment command, increases the amplitude to enhance the vibration friction reduction effect, and accelerates the resistance reduction speed. When the demolding progress index is higher than the threshold, the fuzzy control rule base determines that the plate 6 is about to completely detach from the positioning pin 5, outputs an amplitude reduction command, reduces the amplitude to avoid excessive vibration at the end of demolding and additional impact on the plate 6. This dynamic control mechanism based on resistance feedback overcomes the factor that open-loop control cannot perceive changes in the demolding state, enabling vibration parameters to be adjusted in real time according to the changing trend of demolding resistance, ensuring the continuous effectiveness of vibration friction reduction throughout the demolding process.

[0140] The ultrasonic vibration parameter adaptive control method based on demolding resistance feedback employs a two-layer optimization mechanism of "initial differentiation + process adaptation." The initial differentiation mechanism provides starting parameters adapted to different working conditions based on the characteristics of the sheet material, while the process adaptation mechanism provides dynamic follow-up adjustments to changes in the demolding state. The two optimization mechanisms work together to ensure that the vibration parameters match the actual needs in both the spatial dimension (different sheet material characteristics) and the temporal dimension (demolding process stages). Therefore, it solves the technical problem that fixed vibration parameters cannot adapt to the changing characteristics of the sheet material and the dynamic changes in the demolding process, improving the stability and consistency of demolding effect under different sheet material types and processing conditions.

Claims

1. A stamping die for the top cover of an air conditioner outdoor unit, characterized in that, include: Upper mold assembly, lower mold assembly, and ultrasonic vibration-assisted demolding positioning pin device disposed on the lower mold assembly; The ultrasonic vibration-assisted demolding positioning pin device includes: The positioning pin body is cylindrical and is used to cooperate with the positioning holes on the plate to achieve precise positioning of the plate. A vibration excitation device is disposed at the root of the positioning pin body and is used to generate high-frequency mechanical vibration. A vibration transmission structure is provided, which connects the vibration excitation device and the positioning pin body, and is used to transmit the vibration generated by the vibration excitation device to the positioning pin body. Vibration isolation base, the vibration excitation device is installed on the vibration isolation base, and the vibration isolation base is fixed on the lower mold assembly by vibration isolation pads, so as to limit the vibration within the range of the ultrasonic vibration assisted demolding positioning pin device; A control circuit, which is electrically connected to the vibration excitation device, is used to start the vibration excitation device during the demolding stage after stamping is completed. The vibration excitation device applies high-frequency vibration to the positioning pin body during the demolding stage, causing the positioning pin body to vibrate axially, thereby changing the contact state between the inner wall of the positioning hole of the plate and the surface of the positioning pin body and reducing the demolding friction.

2. The stamping die for the top cover of the air conditioner outdoor unit according to claim 1, characterized in that, The vibration excitation device is an ultrasonic vibrator, which uses a piezoelectric ceramic transducer. The ultrasonic vibrator operates at a frequency of 20-40 kHz and has an amplitude of 5-15 μm.

3. The stamping die for the top cover of the air conditioner outdoor unit according to claim 2, characterized in that, The ultrasonic vibrator adopts a Landervan transducer structure. The Landervan transducer includes a rear cover plate, a piezoelectric ceramic stack, a front cover plate, and an amplitude transformer connected in series. The piezoelectric ceramic stack is formed by pressing multiple piezoelectric ceramic discs together with pre-tightening bolts. The amplitude transformer has a conical or stepped structure to amplify the vibration amplitude.

4. The stamping die for the top cover of the air conditioner outdoor unit according to claim 3, characterized in that, The vibration transmission structure includes: The root of the positioning pin body is machined with a conical surface structure, and the conical surface mates with the output end face of the amplitude transformer. The outer side of the conical surface at the root of the positioning pin body is provided with an external thread section, and the output end of the amplitude rod is provided with an internal thread hole that mates with the external thread section. The conical surface at the root of the positioning pin body is tightly fitted to the end face of the amplitude rod through a threaded fastening connection. A coupling agent is coated between the conical surface at the root of the positioning pin body and the end face of the amplitude transformer. The coupling agent is used to fill the microscopic gaps at the contact interface and improve the vibration transmission efficiency.

5. The stamping die for the top cover of the air conditioner outdoor unit according to claim 1, characterized in that, The vibration isolation base is a cylindrical structure, and the vibration isolation pad is a rubber vibration isolation pad. The rubber vibration isolation pad is disposed between the bottom flange of the vibration isolation base and the platform of the lower mold assembly. The rubber vibration isolation pad is continuously distributed along the circumference of the bottom flange of the vibration isolation base. The vibration isolation base is fixed to the lower mold assembly by bolts passing through the rubber vibration isolation pad.

6. The stamping die for the top cover of an air conditioner outdoor unit according to claim 5, characterized in that, The rubber vibration isolation pad is made of nitrile rubber with a hardness of Shore A 60-80 degrees and a thickness of 3-5mm.

7. The stamping die for the top cover of an air conditioner outdoor unit according to claim 1, characterized in that, The control circuit includes: An ultrasonic generator is provided, wherein the ultrasonic generator is used to output a high-frequency alternating current signal whose frequency matches the resonant frequency of the vibration excitation device, and the output power of the ultrasonic generator is adjustable. A synchronous triggering unit is electrically connected to the control system of the stamping machine. It is used to receive the position signal of the upper die. When the upper die completes the stamping stroke and begins to return to the set position, the synchronous triggering unit triggers the ultrasonic generator to start outputting. The synchronous triggering unit includes a timing control function, which controls the vibration excitation device to automatically shut down after working for a preset time during the demolding stage.

8. A method for controlling the amplitude of a stamping die for an air conditioner outdoor unit top cover, applied to the stamping die for an air conditioner outdoor unit top cover as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 100: Obtain plate characteristic data and generate initial vibration parameters: The measured thickness of the plate is obtained by a laser rangefinder sensor, and the coating type identifier is obtained from the production management system through a communication interface. The measured thickness and the coating type identifier are used as an index to query the parameter mapping table to obtain the corresponding initial values ​​of vibration frequency and amplitude. The initial values ​​of vibration frequency and amplitude are then sent to the ultrasonic generator. Step 200: Obtain real-time demolding resistance data and calculate resistance characteristic indicators: After the upper mold returns, the axial resistance borne by the positioning pin is continuously collected by the piezoelectric force sensor installed at the root of the positioning pin, generating a resistance value sequence. The resistance value sequence is then subjected to sliding difference calculation to calculate the resistance decrease rate at each moment, the initial maximum static friction peak value is recorded, and the ratio of the current resistance value to the initial maximum static friction peak value is calculated to obtain the demolding progress index. Step 300: Generate vibration parameter adjustment commands and execute dynamic control: The resistance decrease rate and the demolding progress index are input into the fuzzy control rule base. An amplitude increment adjustment command is generated according to the fuzzy control rules. The target amplitude is calculated according to the amplitude increment adjustment command. The target amplitude is converted into an ultrasonic generator power control command and output to the ultrasonic generator. Step 400: Determine the demolding completion conditions and output a control signal: When the resistance value in the resistance value sequence is lower than the termination threshold for 50 ms consecutively, the demolding is determined to be complete, and a shutdown command is output to the ultrasonic generator.

9. The method for controlling the amplitude of the stamping die for the top cover of an air conditioner outdoor unit according to claim 8, characterized in that, The fuzzy control rule base includes the following control rules: When the rate of decrease in resistance is less than 0.5 N / ms, the friction reduction effect is deemed insufficient, and an amplitude increment adjustment command is generated with an amplitude increment of +1 μm. When the demolding progress index is greater than 0.8, it is determined that demolding is nearing completion, and an amplitude reduction command is generated with an amplitude increment of -1μm. When the resistance decrease rate is greater than or equal to 0.5 N / ms and the demolding progress index is less than or equal to 0.8, the current parameters are deemed appropriate, and an amplitude holding command is generated with an amplitude increment of 0 μm.

10. The method for controlling the amplitude of the stamping die for the top cover of an air conditioner outdoor unit according to claim 8, characterized in that, The parameter mapping table is established using the following method: Demolding tests were conducted on representative board samples, with board thicknesses covering five calibration points: 0.5mm, 0.8mm, 1.2mm, 1.5mm, and 2.0mm. The coating types included polyester coating, epoxy resin coating, and fluorocarbon coating. Vibration parameter optimization tests were conducted for each combination of thickness and coating type. The vibration frequency was adjusted in 2kHz steps within the range of 20-40kHz, and the amplitude was adjusted in 1μm steps within the range of 5-15μm. Ten repeated tests were conducted on each set of parameters, and the vibration parameter combination with a coating integrity rate of over 95% and the shortest demolding time was selected as the calibration value for this working condition. The calibration results are stored in the controller's non-volatile memory as a two-dimensional array, forming the parameter mapping table.

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