A multi-specification double-layer blister sheet heating and feeding linkage control method

Abstract

The application discloses a multi-specification double-layer blister sheet heating and feeding linkage control method and relates to the technical field of plastic thermoforming control. According to product specifications and the materials, thicknesses and sizes of two sheets, corresponding parameters are called to sequentially complete feeding and layered clamping of a first sheet and a second sheet. In the heating process, the sag state and temperature of the two sheets, the air cavity pressure between the sheets and the lower heating cavity pressure are obtained in the same control cycle, two allowed ranges of the air cavity pressure between the sheets and the allowed range of the lower heating cavity pressure are determined in parallel, the operation boundary of the bottom layer pressure control program is formed according to the overlapping range, the pressure following condition and the state condition to adjust the air cavity pressure of the two sheets. After the heating is completed, the heating plate is withdrawn, mold closing, part taking and sheet changing are performed. The application can reduce the risk of adhesion of the two sheets and contact of the first sheet with the lower heating plate.

Description

Technical Field

[0001] This invention relates to the field of plastic thermoforming control technology, specifically to a method for linkage control of heating and feeding of multi-specification double-layer thermoforming sheets. Background Technology

[0002] Double-layer thermoforming products are typically made from two thermoplastic sheets through feeding, clamping, heating, molding, forming, and cooling. They are widely used in the production of pallets, collapsible boxes, inner linings, and hollow packaging products.

[0003] In the prior art, CN117507324B discloses a single-machine double-layer thermoforming processing equipment. The equipment forms upper and lower plastic sheets through an extruder with two extrusion nozzles, cuts the plastic sheets using a cutting device, and transports the plastic sheets to the upper and lower molds of a press through an upper carriage and a lower carriage, respectively. After the upper and lower molds are closed, the two plastic sheets are fused together and formed into a double-layer thermoformed product through gas injection, pressure holding, cooling, and demolding.

[0004] However, when two sheets are fed sequentially, clamped in layers, and heated simultaneously, the degree of softening of the sheets varies with the material, thickness, size, and temperature. Increased pressure in the inter-sheet air chamber can reduce the sagging of the second sheet, but it also increases the downward force on the first sheet; the pressure in the lower heating chamber also affects the distance between the first sheet and the lower heating plate. Current solutions do not address the issue of a coordinated control method for adjusting the pressure ranges of the two air chambers—which, in a structure with an inter-sheet air chamber between the two sheets and a lower heating chamber below the first sheet—to address the opposing effects of the inter-sheet air chamber pressure on the two sheets, based on the sagging state of the two sheets, temperature, and the pressure of the two air chambers. This could potentially cause the two sheets to stick together or the first sheet to contact the lower heating plate.

[0005] Therefore, it is still necessary to provide a method for linkage control of heating and feeding of multi-specification double-layer thermoforming sheets in order to improve the stability of the heating and forming process of double-layer sheets. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a multi-specification double-layer thermoforming sheet heating and feeding linkage control method. By acquiring the drooping state, temperature, and pressure of the two sheets and the two air chambers during the layering, clamping, and synchronous heating of the double-layer sheets, the allowable pressure range, pressure following conditions, and heating state transition conditions of the two air chambers are determined in parallel. Based on this, the bottom layer pressure adjustment and heating state transition are constrained to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for coordinated control of heating and feeding of multi-specification double-layer thermoforming sheets, the method comprising: acquiring the sag state and temperature of a first sheet and a second sheet during the heating process, the inter-sheet air cavity pressure, and the lower heating cavity pressure; wherein the inter-sheet air cavity is formed between the first sheet and the second sheet, and the lower heating cavity is located below the wellhead with the first sheet as its top boundary; when it is determined that the air cavity pressure needs to be adjusted based on the sag state and temperature of the first sheet and the second sheet, determining the inter-sheet air cavity pressure adjustment range and the lower heating cavity pressure adjustment range based on the sag state, the temperature, the inter-sheet air cavity pressure, and the lower heating cavity pressure; under the current heating state, adjusting the inter-sheet air cavity pressure according to the inter-sheet air cavity pressure adjustment range, and adjusting the lower heating cavity pressure according to the lower heating cavity pressure adjustment range.

[0008] In a preferred embodiment, determining the adjustment range of the inter-sheet air cavity pressure and the adjustment range of the lower heating cavity pressure includes: within the same control cycle, determining a first allowable range of the inter-sheet air cavity pressure based on the sag state and temperature of the second sheet, the inter-sheet air cavity pressure, and the direction of change of the inter-sheet air cavity pressure; within the same control cycle, determining a second allowable range of the inter-sheet air cavity pressure, an allowable range of the lower heating cavity pressure, and an allowable following range of the lower heating cavity pressure relative to the inter-sheet air cavity pressure based on the sag state and temperature of the first sheet, the inter-sheet air cavity pressure, the lower heating cavity pressure, and the respective directions of change of the inter-sheet air cavity pressure and the lower heating cavity pressure; wherein the two determination processes are executed in parallel based on the input data of the same control cycle, and neither determination process uses the output result of the other determination process as input.

[0009] In a preferred embodiment, determining the inter-sheet air cavity pressure adjustment range and the lower heating cavity pressure adjustment range includes: determining the overlapping range of the first allowable range and the second allowable range as the inter-sheet air cavity pressure adjustment range; determining a pressure sub-interval that satisfies the allowable following range from the allowable range of the lower heating cavity pressure based on the current pressure of the inter-sheet air cavity, and determining the pressure sub-interval as the lower heating cavity pressure adjustment range; marking the inter-sheet air cavity pressure adjustment range as invalid when there is no overlapping range between the first allowable range and the second allowable range; marking the lower heating cavity pressure adjustment range as invalid when there is no pressure sub-interval that satisfies the allowable following range from the allowable range of the lower heating cavity pressure; and prohibiting entry into the normal heating state when any of the pressure adjustment ranges is invalid.

[0010] In a preferred embodiment, the method further includes: determining, based on the sag state and temperature of the first sheet and the second sheet, the inter-sheet air cavity pressure, and the lower heating cavity pressure, the permissible pressure change rate of the inter-sheet air cavity and the lower heating cavity in the pressure increase and pressure decrease directions, respectively; and determining the maximum following delay, the shortest state holding time, the result validity time, and the permissible heating state for the lower heating cavity pressure relative to the inter-sheet air cavity pressure; adjusting the inter-sheet air cavity pressure range, the lower heating cavity pressure range, the permissible pressure change rate of the two air cavities in the pressure increase and pressure decrease directions, and the... The maximum follow-up delay, the shortest state holding time, the result validity time, and the allowed heating state are used as the operating boundaries of the pressure control program. Within these operating boundaries, the pressure control program controls the inflation valve and pressure relief valve corresponding to the inter-sheet air chamber based on the relationship between the actual pressure of the inter-sheet air chamber and the pressure adjustment range of the inter-sheet air chamber. It also controls the inflation valve and pressure relief valve corresponding to the lower heating chamber based on the relationship between the actual pressure of the lower heating chamber and the pressure adjustment range of the lower heating chamber. The inflation valve and pressure relief valve corresponding to the same air chamber are interlocked, and only one valve is allowed to be open at any given time.

[0011] In a preferred embodiment, the heating state includes a normal heating state, a limited heating state, a paused heating state, and a safe state; the necessary data for determining the heating state includes the sag state and temperature of the first sheet and the second sheet respectively, the air chamber pressure between the sheets, and the lower heating chamber pressure; when all necessary data are valid, the sag states of the first sheet and the second sheet have not reached the warning state, both pressure adjustment ranges are valid, the actual pressures of the two air chambers are within their respective pressure adjustment ranges, and the actual following delay of the lower heating chamber pressure relative to the air chamber pressure between the sheets does not exceed the maximum following delay, the normal heating state is entered; if the conditions for entering the paused heating state and the safe state are not met, when any of the following... When one of the following conditions is met, the restricted heating state is entered: the sagging state of one of the first sheet and the second sheet is in a warning state, the sagging state of the other sheet is not in a warning state, and both pressure adjustment ranges are effective; there is a slight leak in any air chamber, and the actual pressure of the corresponding air chamber can be maintained within the corresponding pressure adjustment range; if the conditions for entering the safety state are not met, when the sagging states of both the first sheet and the second sheet are in a warning state, or the actual following delay exceeds the maximum following delay, the heating pause state is entered; when the sagging state of any sheet is in a stopped state, any pressure adjustment range is invalid, the actual pressure of any air chamber exceeds the corresponding safe pressure range, or any necessary data is invalid, the safety state is entered.

[0012] In a preferred embodiment, the priority of the safety state, the paused heating state, the restricted heating state, and the normal heating state decreases sequentially, and only one heating state is allowed to be active at any given time. When the entry condition for the safety state is met in any heating state, the system enters the safety state. In the restricted heating state, if all necessary data is valid, the sagging states of both the first and second sheets have returned to a state not reaching the warning level, both pressure adjustment ranges are valid, the actual pressures of both air chambers have entered their respective pressure adjustment ranges, the actual following delay does not exceed the maximum following delay, there is no leakage abnormality, and the minimum state holding time is continuously reached, the system returns to the normal heating state. In the restricted heating state and without meeting the entry condition for the safety state, when the sagging states of both the first and second sheets are... When any of the following conditions are met: alert state, actual following delay exceeding maximum following delay, or restricted heating state reaching the corresponding maximum allowable time, the heating is paused. In the paused heating state, if all necessary data is valid, the sag of the first and second sheets has returned to a state not meeting the alert, both pressure adjustment ranges are valid, the actual pressure of both air chambers has entered their respective pressure adjustment ranges, the actual following delay does not exceed the maximum following delay, and the minimum state holding time is continuously reached, the heating is paused. If the paused heating state reaches the corresponding maximum allowable time but does not meet the conditions for entering the restricted heating state, the heating is safe. The minimum state holding time does not restrict transition to a higher priority heating state, and the safe state does not automatically return to the normal heating state.

[0013] In a preferred embodiment, before acquiring the drooping state, the temperature, the inter-sheet air cavity pressure, and the lower heating cavity pressure, the method further includes: with the upper and lower frames locked, conveying the first sheet between the wellhead and the lower frame, and causing the upper and lower frames to move synchronously to clamp the first sheet between the wellhead and the lower frame; releasing the locking relationship between the upper and lower frames, causing the upper frame to move relative to the lower frame, conveying the second sheet between the upper and lower frames, and causing the upper frame to move towards the lower frame to clamp the second sheet between the upper and lower frames; performing a sealing test on the inter-sheet air cavity formed after clamping the first and second sheets, and allowing the upper heating plate and the lower heating plate to enter after the inter-sheet air cavity sealing test is qualified.

[0014] In a preferred embodiment, after the air cavity between the sheets passes the sealing test, the upper heating plate is moved above the second sheet, and the lower heating plate is moved into the lower heating cavity. After the upper and lower heating plates reach the heating position, the lower heating cavity is tested for sealing, and heating begins after the sealing test is passed. Heating is completed when both the first and second sheets reach their respective molding temperature ranges, the sagging of both sheets has not reached the warning state, both pressure adjustment ranges are effective, and the actual pressure of both air cavities remains stable within their respective pressure adjustment ranges. When the time is recognized, the upper heating plate and the lower heating plate are controlled to retract. During the retraction of the upper heating plate and the lower heating plate, the sag status and temperature of the first sheet and the second sheet, the air chamber pressure between the sheets, and the lower heating chamber pressure are continuously acquired, and the corresponding air chamber pressures are continuously adjusted according to the air chamber pressure adjustment range between the sheets and the lower heating chamber pressure adjustment range. When the upper heating plate and the lower heating plate are completely retracted and their positions are valid, the sag status of the first sheet and the second sheet has not reached the warning state, and the pressure data of the two air chambers are valid and the actual pressure is stable, the molding preparation state is allowed.

[0015] In a preferred embodiment, the method further includes: recording corresponding effective parameters based on product specifications, the material, length, width, and thickness of the first and second sheets, and the volumes of the air cavity between the sheets and the lower heating cavity; the effective parameter records include molding temperature range, allowable sag range, sealing detection parameters, pressure boundary parameters for determining the first and second allowable ranges, pressure boundary parameters for determining the allowable range of pressure in the lower heating cavity and the allowable following range, the allowable pressure change rate, the maximum following delay, the shortest state holding time, and the result. Effective time; when there are no corresponding effective parameter records for the combination of the current product specifications, the material, length, width, and thickness of the first and second sheets, and the volume of the inter-sheet air cavity and the lower heating cavity, without causing the first and second sheets to reach their respective warning positions, the pressure of the inter-sheet air cavity and the pressure of the lower heating cavity are changed at the initial, middle, and later stages of sheet heating, respectively. The sag state and temperature of the first and second sheets, the inter-sheet air cavity pressure, the lower heating cavity pressure, and the response time before and after the pressure change are recorded to obtain multiple effective records; consistency. The requirements are that the changing trend of the sheet sagging state in multiple valid records is consistent, and the differences between the pressure boundaries and the differences between the pressure response times determined by the multiple valid records do not exceed their respective consistency ranges determined based on the corresponding detection errors and repeated test fluctuations; when the multiple valid records meet the consistency requirements, the first allowable range and the second allowable range determined based on the multiple valid records overlap, and there is a pressure sub-interval in the allowable range of the lower heating chamber pressure that meets the allowable following range, the pressure boundary parameters, the allowable pressure change rate, and the... are determined based on the multiple valid records. The maximum follow-up delay, the shortest state holding time, and the result validity time are determined and associated with the product specifications, the materials, lengths, widths, and thicknesses of the first and second sheets, and the volumes of the air cavities between the sheets and the lower heating cavity, and a valid parameter version is generated. If multiple valid records fail to meet the consistency requirements, the first allowable range and the second allowable range do not overlap, or there is no pressure sub-interval in the allowable range of the lower heating cavity pressure that meets the allowable follow-up range, the current parameter calibration result is marked as invalid, and automatic production using the current sheet combination is prohibited.

[0016] A controller for a double-layer sheet thermoforming device includes a processor, a memory, and an input / output interface. The memory stores control programs, product specifications, sheet parameters, air cavity parameters, calibration parameters, and parameter versions. The input / output interface acquires the drooping state and temperature of the first and second sheets, the pressure of the inter-sheet air cavity formed between the first and second sheets, and the pressure of the lower heating cavity located below the first sheet. The input / output interface also acquires the position of the feeding mechanism and the sheet's positioning status, the position and locking status of the upper and lower frames, and the positions and locking status of the upper and lower heating plates. The input / output interface is used to acquire product specifications, the material, length, width, and thickness of the first and second sheets, and the volume of the air cavity between the sheets and the lower heating cavity, and to output air cavity pressure control signals, heating control signals, and actuator action control signals. The processor is used to execute the control program to perform the multi-specification double-layer thermoforming sheet heating and feeding linkage control method described in this embodiment.

[0017] The present invention has the following beneficial effects: This invention obtains the sag status, temperature, and pressure of the two air chambers of the two sheets within the same control cycle, and determines the allowable pressure range, pressure change rate, and pressure following conditions of the air chamber between the sheets and the lower heating chamber in parallel. This allows the two air chambers to be linked and adjusted under common constraints, reducing the risk of the second sheet sticking to the first sheet and the first sheet contacting the lower heating plate.

[0018] This invention determines the feeding position, layer clamping sequence, heating parameters, and droop control parameters based on product specifications and the materials, dimensions, and thicknesses of the two sheets. This ensures that sequential feeding, synchronous heating, heating plate removal, and mold closing are interconnected, improving the equipment's adaptability to multiple specifications and different materials and thicknesses of the sheets.

[0019] This invention utilizes parallel judgment results to limit the boundary of bottom pressure control and heating state transition, and performs restricted heating, pause heating or safety handling for working conditions such as drooping warning, air cavity leakage, pressure follow-up timeout and invalid detection data. This helps to improve the stability of the molding process and reduce the possibility of abnormal sheet contact, air cavity pressure runaway and unqualified molding. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the double-layer sheet vacuum forming equipment of the present invention.

[0022] Figure 2 This is a schematic diagram showing the gas supply connection between the air cavity between the sheets and the lower heating cavity of the present invention.

[0023] Figure 3 This is a schematic diagram of the sequential feeding and layered clamping process of the first and second sheets of the present invention.

[0024] Figure 4 This is a schematic diagram of the air cavity between the sheets, the lower heating cavity, and the drooping relationship of the two sheets in this invention.

[0025] Figure 5 This is a flowchart of the multi-specification double-layer thermoforming sheet heating and feeding linkage control method of the present invention.

[0026] Figure 6 This is a logic diagram for determining the parallel drooping of the two sheets and the range of pressure adjustment in this invention.

[0027] Figure 7 This is a schematic diagram of the heating state transition relationship of the present invention.

[0028] Figure 8 This is a flowchart of the multi-specification sheet parameter calibration and parameter version management process of the present invention.

[0029] 100. Double-layer sheet vacuum forming equipment; 110. Wellhead; 120. Middle frame; 121. Upper frame; 122. Lower frame; 130. Feeding mechanism; 140. Upper heating plate; 150. Lower heating plate; 160. Upper mold; 170. Lower mold; 180. Air supply device; 190. First sheet; 200. Second sheet; 210. Air cavity between sheets; 220. Lower heating cavity; 230. Sheet sag detection device; 240. Temperature detection device; 250. Pressure detection device. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] like Figure 1 As shown, the present invention is applied to a double-layer sheet vacuum forming equipment 100. The double-layer sheet vacuum forming equipment 100 includes an opening 110, a middle frame 120, a feeding mechanism 130, an upper heating plate 140, a lower heating plate 150, an upper mold 160, a lower mold 170, an air supply device 180, a sheet sagging detection device 230, a temperature detection device 240, a pressure detection device 250, and a controller.

[0032] The middle frame 120 includes an upper frame 121 and a lower frame 122 that are capable of relative movement. When the upper frame 121 and lower frame 122 are locked, they can rise and fall synchronously. After the locking relationship is released, the lower frame 122 remains at the wellhead 110, and the upper frame 121 can rise and fall relative to the lower frame 122. The controller acquires the locking state, position state, and action completion state of the upper frame 121 and lower frame 122, respectively. If the locking state and the unlocking state are simultaneously valid, simultaneously invalid, or the state transition is not completed within the corresponding maximum allowable time, the movement of the middle frame 120 is stopped and a corresponding fault code is output.

[0033] like Figure 3 and Figure 4 As shown, the periphery of the first sheet 190 is clamped between the lower frame 122 and the wellhead 110, and the periphery of the second sheet 200 is clamped between the upper frame 121 and the lower frame 122. The first sheet 190, the second sheet 200, and the inner peripheral wall of the lower frame 122 together define the inter-sheet air cavity 210. The lower heating cavity 220 is located below the first sheet 190. The first sheet 190 forms the top boundary of the lower heating cavity 220, and the peripheral wall of the wellhead 110, the lower mold 170 located below, and the sealing part at the lateral entry channel of the lower heating plate 150 form the other boundaries of the lower heating cavity 220. Before heating begins, the lower heating plate 150 enters the lower heating cavity 220 through the lateral entry channel and remains within the lower heating cavity 220 during heating, maintaining a heating distance from the first sheet 190.

[0034] The pressure in the inter-sheet air cavity 210 acts upward on the second sheet 200 and downward on the first sheet 190; the pressure in the lower heating cavity 220 acts upward on the first sheet 190. Increasing the pressure in the inter-sheet air cavity 210 can reduce the downward sag of the second sheet 200 towards the first sheet 190, while potentially increasing the force on the first sheet 190 towards the lower heating plate 150. Increasing the pressure in the lower heating cavity 220 can improve the upward support effect on the first sheet 190.

[0035] When the second sheet 200 is connected to the external environment, the air pressure support exerted on the second sheet 200 is determined by the pressure difference between the pressure in the inter-sheet air chamber 210 and the external environment pressure. The net air pressure exerted on the first sheet 190 is determined by the pressure difference between the pressure in the lower heating chamber 220 and the pressure in the inter-sheet air chamber 210. When the pressure in the lower heating chamber 220 increases relative to the pressure in the inter-sheet air chamber 210, the upward support exerted on the first sheet 190 increases; when the pressure in the inter-sheet air chamber 210 increases relative to the pressure in the lower heating chamber 220, the downward force exerted on the first sheet 190 increases. The allowable following range of the two air chambers is used to limit the pressure difference, the direction of pressure change, and the pressure response time between the two air chambers, so as to simultaneously maintain a safe distance between the second sheet 200 and the first sheet 190, and a safe distance between the first sheet 190 and the lower heating plate 150.

[0036] The upper heating plate 140 enters from the side of the equipment above the second sheet 200. The lower heating plate 150 enters the lower heating chamber 220 through a lateral entry channel. High-temperature resistant elastic seals are provided on the upper and lower sides of the lateral entry channel, and the two high-temperature resistant elastic seals are arranged opposite each other and slide in contact with the upper and lower surfaces of the lower heating plate 150, respectively.

[0037] The high-temperature resistant elastic seal is installed in a removable clamping seat. The clamping seat applies a preload force to the high-temperature resistant elastic seal towards the lower heating plate 150 to compensate for seal wear, installation errors, and thickness errors of the lower heating plate 150. During the entry, stay, and withdrawal of the lower heating plate 150, the two high-temperature resistant elastic seals continuously press against the corresponding surfaces of the lower heating plate 150, keeping the lower heating chamber 220 isolated from the external environment.

[0038] The lower heating plate 150 has a sealing plate at its tail end corresponding to the lateral entry channel. When the lower heating plate 150 is completely retracted, the sealing plate moves to the closed position of the lateral entry channel and presses against the sealing part around the lateral entry channel. The power supply connection part and guide connection part of the lower heating plate 150 are located on the side of the sealing plate away from the lower heating cavity 220 and do not pass through the pressing and sealing area between the sealing plate and the lateral entry channel.

[0039] The sealing status of the lateral entry channel is determined based on the position of the lower heating plate 150, the position of the sealing plate, and the pressure build-up time and pressure drop of the lower heating chamber 220 under the detection pressure. If the lower heating plate 150 fails to reach the corresponding position, the sealing plate fails to reach the corresponding closing position, the pressure build-up time exceeds the allowable pressure build-up time, or the pressure drop exceeds the allowable value, the sealing status of the lateral entry channel will be marked as invalid.

[0040] The material, preload, and allowable operating temperature of the high-temperature resistant elastic seal are determined based on the surface temperature of the lower heating plate 150, the maximum allowable pressure of the lower heating chamber 220, the number of reciprocating movements, and the allowable leakage. If the high-temperature resistant elastic seal develops cracks, permanent deformation, or wear exceeding the allowable value, or if the lower heating chamber 220 continuously fails the sealing test, the current seal should be discontinued and replaced.

[0041] like Figure 2 As shown, the inter-sheet air chamber 210 and the lower heating chamber 220 are each equipped with independent air inlets, pressure relief ports, air inlets, pressure relief valves, pressure detection devices 250, and safety valves. The air paths of the two chambers do not merge before entering their respective chambers. The pressure detection devices 250 acquire the pressure of the inter-sheet air chamber 210 and the lower heating chamber 220, respectively. The pressures of both chambers are expressed as gauge pressure relative to the external ambient pressure.

[0042] The safety valve set pressure is higher than the maximum allowable pressure of the air chamber for the controller, but lower than the pressure that may damage the sheet, frame seals, or air circuit components. The safety valve set pressure is determined based on the air chamber pressure resistance test, the maximum allowable differential pressure of the sheet, and the rated pressure of the air circuit components. Parameter adjustments during the production process do not change the safety valve set pressure.

[0043] In this embodiment, the safe pressure range is an insurmountable range determined based on the pressure resistance of the air chamber, the maximum permissible pressure difference of the sheet, and the rated pressure of the air circuit components. The first permissible range, the second permissible range, and the permissible pressure range of the lower heating chamber 220 are candidate pressure ranges determined based on the sheet temperature, the sheet sagging state, and the direction of air chamber pressure change. The pressure adjustment range of the inter-sheet air chamber 210 and the pressure adjustment range of the lower heating chamber 220 are operating ranges formed after screening for overlapping ranges and pressure following conditions of the candidate pressure ranges within the current control cycle. Neither of these pressure adjustment ranges shall exceed the safe pressure range of the corresponding air chamber.

[0044] The effective parameter record is used to store the calibrated applicable conditions, pressure boundary parameters, and timing parameters. Applicable conditions include at least product specifications, sheet material, sheet length, sheet width, sheet thickness, air chamber volume, temperature range, sheet sag status, and air chamber pressure change direction. Pressure boundary parameters include at least candidate lower and upper pressure limits for determining the first and second allowable ranges, candidate pressure boundaries for determining the allowable pressure range of the lower heating chamber 220, and pressure difference boundaries and pressure correspondences for determining the allowable following range.

[0045] The first allowable range, the second allowable range, the allowable range of pressure in the lower heating chamber 220, and the allowable following range are dynamically determined by the controller within the current control cycle based on real-time input data and corresponding valid parameter records. The pressure adjustment range of the inter-sheet air chamber 210 and the pressure adjustment range of the lower heating chamber 220 are control results formed in the current control cycle and are associated with and saved with the current input data, parameter version, control cycle, and result validity time. The pressure adjustment range is not directly written into the valid parameter version as a fixed parameter.

[0046] The sheet sag detection device 230 detects the sag of the second sheet 200 towards the first sheet 190, and the sag of the first sheet 190 towards the lower heating plate 150. When using a through-beam photoelectric sensor, multiple sets of detection optical paths are set in the central and peripheral areas of the sheet. The sheet is considered safe when it has not entered the corresponding warning position; it is considered a warning state when it has entered the warning position but has not reached the stop position; and it is considered a stop state when it reaches a position where the two sheets may stick together or the first sheet 190 may contact the lower heating plate 150.

[0047] When any enabled detection point outputs a stop status, the corresponding sheet is determined to be in a stop state; when there is no stop state and at least one enabled detection point outputs a warning status, the corresponding sheet is determined to be in a warning state; when all enabled detection points output a safe status, the corresponding sheet is determined to be in a safe state. Invalid detection results are not interpreted as a safe state.

[0048] If some detection points are invalid, but the remaining valid detection points can still cover the central area of ​​the sheet and the surrounding key areas corresponding to the current specification, and can determine the overall sagging state of the corresponding sheet, then the corresponding sheet sagging state data will be marked as downgraded valid, and a return from restricted heating state to normal heating state will be prohibited. If the remaining valid detection points are insufficient to determine the overall sagging state of any sheet, then the corresponding sheet sagging state data will be marked as invalid and the process will enter a safe state.

[0049] The warning position, stop position, and state boundary advance are calibrated based on the initial spacing of the sheet, detection error, control cycle, air path response time, valve response time, residual sag of the sheet, and the minimum safety distance to be maintained, and are associated with and stored in relation to the sheet specifications and detection position.

[0050] Temperature detection device 240 acquires the temperatures of the first sheet 190 and the second sheet 200, respectively. When multiple temperature detection positions are used, the temperature data corresponding to the spatial position of each drooping detection area is used. When a single sheet temperature needs to be determined, the effective temperature value corresponding to the detection position with the highest degree of softening is selected based on the correlation between the current sheet material temperature and softening state. When heating is deemed complete, the temperature corresponding to each activated heating area should be within the forming temperature range of the corresponding sheet.

[0051] If any detection data has no output, exceeds the measurement range, exceeds the acquisition time, contradicts related detection results, or cannot form a corresponding control result, the data will be marked as invalid. If the detection results contradict each other, the data will be re-acquired within a preset confirmation time; if the corresponding status still cannot be determined after re-acquisition, the corresponding data will be marked as invalid.

[0052] The controller includes a processor, memory, and input / output interfaces. The memory stores control programs, product specifications, sheet parameters, air chamber parameters, calibration parameters, and parameter versions. The input / output interfaces acquire the sag and temperature of the two sheets, the pressure of the two air chambers, the position of the feeding mechanism 130 and the sheet's arrival status, the position and locking status of the upper frame 121 and lower frame 122, the position status of the two heating plates, the sealing status of the lateral entry channel, the sealing status of the two air chambers, the operation status of the inflation valve and pressure relief valve, and the position status of the upper die 160 and lower die 170. It also outputs air chamber pressure control signals, heating control signals, and actuator operation control signals.

[0053] The control program operates according to a preset control cycle. Input data includes at least the acquired value, acquisition time, and valid status. Control results include at least the pressure adjustment range of the inter-sheet air chamber 210, the pressure adjustment range of the lower heating chamber 220, the allowable pressure change rate of the two air chambers in the pressure increase and decrease directions, the maximum following delay, the shortest state holding time, the result validity time, the allowed heating state, the data validity status, and the result status code.

[0054] Controller according to Figure 5 The process shown follows four steps.

[0055] Example 1 illustrates the complete production process, including product specification determination, sequential feeding and layered clamping, synchronous heating and drooping linkage control, mold closing and forming, and part removal and replacement.

[0056] Step 1: The controller obtains the product specifications, as well as the material, length, width, and thickness of the first sheet 190 and the second sheet 200.

[0057] The controller determines the clamping positions of the upper frame 121 and the lower frame 122, the edge positioning positions of the sheet, the heating areas that the upper heating plate 140 and the lower heating plate 150 need to be activated, the detection positions that the sheet sagging detection device 230 needs to be activated, and the mold closing positions of the upper mold 160 and the lower mold 170, the motion synchronization range, the molding pressure range, the molding time, and the cooling time according to the product specifications.

[0058] The controller determines the molding temperature range, maximum heating time, allowable heat exposure time, and allowable sag range based on the material and thickness of each of the two sheets. When the materials or thicknesses of the two sheets are different, the controller calls up the parameters corresponding to each sheet.

[0059] The sheet heating process is divided into three stages: initial heating, intermediate heating, and final heating. The initial heating stage corresponds to the temperature range before detectable sagging occurs; the intermediate heating stage corresponds to the stage where detectable sagging has occurred and the temperature is below the forming temperature range; and the final heating stage corresponds to the stage approaching or within the forming temperature range. The boundaries, switching hysteresis, and confirmation time of each temperature stage are calibrated based on sheet softening tests, detection errors, and heating inertia.

[0060] The controller retrieves the corresponding valid parameter records based on product specifications, sheet parameters, frame position, activated heating area, activated detection position, and air chamber volume. Valid parameter records include at least the sealing detection parameters, pressure boundary parameters for determining the first and second allowable ranges, pressure boundary parameters for determining the allowable pressure range and allowable following range of the lower heating chamber 220, allowable pressure change rate, maximum following delay, minimum state holding time, result validity time, and applicable conditions for each parameter.

[0061] Within the current control cycle, the controller selects the corresponding pressure boundary parameters from the effective parameter record based on the current temperature stage, sag state, pressure of the air chamber 210 between the two sheets, pressure of the lower heating chamber 220, and the pressure change direction of each air chamber, and dynamically determines each allowable range.

[0062] If there are no valid parameter records for the current product specifications and sheet combination, the parameter version is inconsistent with the equipment configuration, or changes occur in the frame sealing part, air circuit components, pressure detection device 250 and heating plate position that affect the control parameters, the equipment enters the debugging state and is calibrated according to Example 2.

[0063] Step two, as Figure 3 As shown, in the initial state, the upper frame 121 and the lower frame 122 are locked. The feeding mechanism 130 uses the suction part to pick up the first sheet 190 and convey the first sheet 190 between the well opening 110 and the lower frame 122. After the feeding mechanism 130 exits the clamping area, the upper frame 121 and the lower frame 122 move downwards synchronously, so that the periphery of the first sheet 190 is clamped between the lower frame 122 and the well opening 110.

[0064] The controller determines whether the first sheet 190 has been successfully clamped based on the positioning status of the first sheet 190, the position of the lower frame 122, and the clamping status. If any status is invalid, the movement of the middle frame 120 is stopped, and the feeding of the second sheet 200 is prohibited.

[0065] After the first sheet 190 is clamped, the upper frame 121 and lower frame 122 are released from their locking relationship. The lower frame 122 remains at the wellhead 110 position, and the upper frame 121 moves upward to form a feeding space for the second sheet 200. The feeding mechanism 130 picks up the second sheet 200 and conveys it between the upper frame 121 and lower frame 122. After the feeding mechanism 130 retracts, the upper frame 121 moves downward, clamping the periphery of the second sheet 200 between the upper frame 121 and lower frame 122.

[0066] If the feeding mechanism 130, middle frame 120, upper frame 121, lower frame 122, or locking part fails to complete its action within the corresponding maximum allowable time, the relevant actuator will stop and a fault code will be output. The maximum allowable time is calibrated based on the movement stroke, allowable movement speed, and position detection response time.

[0067] After the two sheets are clamped together, an air cavity 210 is formed between the sheets. The air cavity sealing test includes closing the corresponding pressure relief valve, applying test pressure to the air cavity, obtaining the pressure build-up time, stopping inflation after the pressure stabilizes, performing pressure holding and obtaining the pressure drop during the holding period. If the pressure build-up time exceeds the allowable pressure build-up time or the pressure drop during the holding period exceeds the allowable value, the sealing test is deemed unqualified.

[0068] If the sealing test of the air cavity 210 between the sheets fails, a retest is allowed before heating begins. If the retest also fails, the pressure in the air cavity 210 between the sheets is released in a controlled manner, and the current production cycle ends.

[0069] The sealing test parameters are calibrated based on the air cavity volume, sheet cold stiffness, pressure detection resolution, and sealing test results. If the sheet moves beyond the allowable range during the sealing test, the test is stopped and the current test record is marked as invalid.

[0070] Step 3: After the sealing test of the air cavity 210 between the sheets is passed, the upper heating plate 140 enters above the second sheet 200, and the lower heating plate 150 enters the lower heating cavity 220. During the movement of the heating plates, the heating elements are kept off, and the position status of the two heating plates and the sealing status of the lateral entry channel are continuously acquired.

[0071] After both heating plates have reached their heating positions and the lateral entry channel is effectively sealed, the lower heating chamber 220 is tested for sealing while the lower heating plate 150 is in its actual heating position. The sealing test parameters for the lower heating chamber 220 are determined based on its current effective volume, the position of the lower heating plate 150, and the sealing status of the lateral entry channel.

[0072] If the sealing test of the lower heating chamber 220 fails, keep the heating element off and allow one retest. If the retest also fails, release the pressure in both air chambers in a controlled manner, remove the heating plate, and end the current production cycle.

[0073] Heating begins after the lower heating chamber 220 passes the sealing test. Within the same control cycle, the controller acquires the sag status and temperature of the two sheets, the pressure of the air chamber 210 between the sheets, the pressure of the lower heating chamber 220, the cumulative opening time of the inflation valves corresponding to the two air chambers, the action feedback status of the inflation valves and the pressure relief valves, as well as the acquisition time and validity status of each data.

[0074] In one implementation, the control cycle is between 20 and 50 milliseconds. Data used for judging the sagging of the two sheets utilizes the same acquisition trigger signal or a unified time reference. The allowable acquisition time difference is calibrated based on the time required for the sheet to move from the warning position to the stop position and the pressure control response time. If the actual acquisition time difference exceeds the corresponding allowable value, the data for this control cycle is marked as invalid.

[0075] The controller re-determines the pressure regulation range of the two air chambers when the first effective control cycle after heating begins, when the sagging state of any sheet changes, when the temperature of any sheet enters a new temperature stage, when any sagging detection result enters the state boundary advance range, or when the current control result reaches the result validity time. If the above conditions are not met and the current control result is still within the result validity time, the current operating boundary continues to be used.

[0076] like Figure 6 As shown, the controller retrieves the corresponding parameter record from the currently valid parameter version based on product specifications, sheet parameters, temperature stage, drooping state, and air chamber pressure change direction. The parameter record includes at least the applicable conditions, candidate pressure boundaries for determining the first and second allowable ranges, candidate pressure boundaries for determining the allowable pressure range of the lower heating chamber 220, pressure difference boundaries and pressure correspondence for determining the allowable following range, allowable pressure change rate, maximum following delay, minimum state holding time, result validity time, and allowable heating state.

[0077] If the input data exceeds the calibrated range, the corresponding parameter record does not exist, or the parameter version is invalid, range extrapolation will not be performed, and the corresponding judgment result will be marked as invalid. When the input data is located between two adjacent calibrated intervals, the corresponding allowable range will only be determined if the adjacent parameter records have common applicable conditions and common pressure boundaries.

[0078] When combining adjacent parameter records used to determine the same allowable range, the larger value among the candidate lower pressure limits is selected as the current candidate lower pressure limit, and the smaller value among the candidate upper pressure limits is selected as the current candidate upper pressure limit. A corresponding allowable range is formed when the current candidate lower pressure limit is not higher than the current candidate upper pressure limit; when the current candidate lower pressure limit is higher than the current candidate upper pressure limit, the corresponding judgment result is marked as invalid.

[0079] Within the same control cycle, the controller performs the upper sheet sagging judgment and the lower sheet sagging judgment in parallel.

[0080] The upper sheet sagging is determined based on the sagging state and temperature of the second sheet 200, the pressure of the inter-sheet air cavity 210 and its direction of change, to determine the first allowable range of the pressure of the inter-sheet air cavity 210, and to determine the corresponding allowable pressure change rate, the effective time of the result and the allowable heating state.

[0081] The lower sheet sagging judgment is based on the sagging state and temperature of the first sheet 190, the pressure of the inter-sheet air cavity 210, the pressure of the lower heating cavity 220, and the pressure change direction of each of the two air cavities. This determines the second allowable range of the pressure of the inter-sheet air cavity 210, the allowable range of the pressure of the lower heating cavity 220, the allowable following range, the allowable pressure change rate, the maximum following delay, the effective time of the result, and the allowable heating state.

[0082] The two decisions are executed in parallel based on data from the same control cycle, and neither decision takes the output of the other as input.

[0083] The pressure boundary parameters used to determine the allowable following range include at least the pressure range of the inter-sheet air chamber 210, the pressure range of the lower heating chamber 220, the lower limit of the allowable pressure difference, the upper limit of the allowable pressure difference, the applicable temperature stage, the applicable sheet sag state, the applicable pressure change direction, and the maximum following delay. The controller determines the allowable following range for the current control cycle based on the current pressure of the two air chambers, the current temperature stage, the sag state of the first sheet 190, and the respective pressure change directions of the two air chambers.

[0084] The controller selects the larger of the two lower limits of the first and second allowable ranges as the lower limit of the pressure adjustment range of the inter-sheet air chamber 210, and selects the smaller of the two upper limits as the upper limit of the pressure adjustment range of the inter-sheet air chamber 210. When the obtained lower limit is not higher than the upper limit, the overlapping range of the two allowable ranges is determined as the pressure adjustment range of the inter-sheet air chamber 210; when the obtained lower limit is higher than the upper limit, the pressure adjustment range of the inter-sheet air chamber 210 is marked as invalid.

[0085] The controller uses the overlap between the allowable pressure range of the lower heating chamber 220 and its safe pressure range as a candidate range, and determines a pressure sub-range that meets the allowable following range based on the current pressure of the inter-sheet air chamber 210 and the allowable pressure difference range. If such a pressure sub-range exists, it is determined as the pressure adjustment range of the lower heating chamber 220; if no pressure sub-range meets the allowable following range, the pressure adjustment range of the lower heating chamber 220 is marked as invalid.

[0086] The permissible rate of pressure change is determined separately for the two air chambers and for the directions of pressure increase and decrease. When multiple rate limits exist in the same direction, the rate with the smaller permissible change amplitude is used. If a pressure change in a certain direction would cause any sheet to continue approaching its corresponding stop position, the permissible rate of pressure change in that direction is set to zero.

[0087] The actual pressure following delay is calculated from the moment the pressure change in the inter-sheet air chamber 210 reaches the pressure following trigger value until the pressure in the lower heating chamber 220 enters the allowable following range and reaches a stable pressure state. The pressure following trigger value is calibrated based on pressure detection noise, valve action dead zone, and control cycle. If the pressure change in the inter-sheet air chamber 210 does not reach the pressure following trigger value, the actual following delay state is marked as not triggered and treated as not exceeding the maximum following delay; timing begins after the pressure change in the inter-sheet air chamber 210 reaches the pressure following trigger value.

[0088] The controller uses two pressure regulation ranges, the allowable pressure change rates of the two air chambers in the pressure increase and decrease directions, the allowable following range, the maximum following delay, the shortest state holding time, the result validity time, and the allowed heating states as the operating boundaries of the pressure control program. The two judgment results are not weighted and summed.

[0089] The pressure control program controls the inflation valve and pressure relief valve corresponding to the two air chambers respectively within the operating boundaries. When the actual pressure is lower than the lower limit of the corresponding pressure adjustment range, the inflation valve is controlled to inflate within the allowable pressure change rate; when the actual pressure is higher than the upper limit of the corresponding pressure adjustment range, the pressure relief valve is controlled to release pressure within the allowable pressure change rate; when the actual pressure is within the corresponding pressure adjustment range, the current pressure is maintained or a pressure correction not exceeding the allowable pressure change rate is performed.

[0090] The inflation valve and pressure relief valve in the same air chamber are interlocked, and only one valve is allowed to be open at a time. If the valve action direction is inconsistent with the actual pressure change direction, or if a identifiable pressure change does not occur within the calibrated response time after the valve action, the corresponding pressure control result will be marked as invalid.

[0091] like Figure 7 As shown, the heating states include normal heating state, limited heating state, paused heating state, and safe state. The priority of the safe state, paused heating state, limited heating state, and normal heating state decreases in that order, and only one heating state is allowed to be active at any given time.

[0092] When all necessary data are valid, both sheets are in a safe state, both pressure adjustment ranges are valid, the actual pressure of both air chambers is within their respective pressure adjustment ranges, and the actual pressure following delay does not exceed the maximum following delay, the system enters normal heating mode.

[0093] If the conditions for pausing heating and entering the safe state are not met, and only one sheet enters the warning state while the other sheet remains in the safe state, and both pressure regulation ranges are effective, then the system enters the restricted heating state. In the restricted heating state, the direction of pressure change that continues to bring the warning sheet closer to the stop position is limited, and the heating power is also limited from further increasing.

[0094] Under restricted heating conditions, when all necessary data are valid, both sheets have returned to a safe state, both pressure adjustment ranges are valid, the actual pressure of both air chambers has entered its respective pressure adjustment range, the actual pressure following delay has not exceeded the maximum following delay, the leakage anomaly has been eliminated, and the minimum state holding time has been continuously reached, the system returns to normal heating conditions.

[0095] When both sheets enter a state of alert under limited heating conditions and the conditions for entering a safe state are not met, or when the actual pressure following delay exceeds the maximum following delay, or when any of the conditions for the limited heating conditions to reach the corresponding longest allowable time are met, the heating will be paused.

[0096] When the heating is paused, the sheet temperature is stopped from increasing further. The pressure control program maintains sheet support within the operating boundary, preventing either sheet from approaching the stop position. The restricted heating state is entered when all necessary data are valid, both sheets have returned to a safe state, both pressure adjustment ranges are valid, the actual pressure in both air chambers has entered its respective pressure adjustment range, the actual pressure follow-up delay does not exceed the maximum follow-up delay, and the minimum state holding time is consistently reached. The safe state is entered when the heating pause reaches its corresponding maximum allowable time and the conditions for entering the restricted heating state are not met.

[0097] The system enters a safe state when any sheet enters a stopped state, any pressure adjustment range becomes invalid, the actual pressure in any air chamber exceeds the corresponding safe pressure range, or any necessary data becomes invalid. There is no limit to the shortest state holding time before transitioning to a higher priority heating state; the safe state does not automatically return to the normal heating state.

[0098] After entering the safe state, the heating power supply to the upper heating plate 140 and the lower heating plate 150 is cut off, and the direction of pressure change that would cause the sheet to continue approaching the stop position is restricted. When the second sheet 200 enters the stop state, the pressure in the inter-sheet air chamber 210 is not allowed to continue to decrease; when the first sheet 190 enters the stop state, the pressure in the inter-sheet air chamber 210 is not allowed to continue to increase, nor is the pressure in the lower heating chamber 220 allowed to continue to decrease.

[0099] When the first sheet 190 and the second sheet 200 simultaneously enter the stop state, the controller redetermines the permissible pressure change direction for each of the two air chambers based on the current valid parameter records, the current positions of the two sheets, the temperature stage, and the actual pressure of the two air chambers. The valid parameter records include the permissible and prohibited pressure change directions of the two air chambers under different combinations of sheet sag states, the applicable temperature stage, the valid status of the common safety direction, and the verification results.

[0100] Pressure adjustment in a given direction is permitted only if the current valid parameter records confirm that no sheet will continue to approach the corresponding stop position. If no pressure change direction simultaneously satisfies the safety distance requirements for both sheets, automatic inflation and depressurization of both air chambers must be stopped, the heating power supply must be kept off, and the current production cycle must end after necessary safety depressurization.

[0101] During heating, the controller checks for leaks in the sheet-interlayer air chamber 210 and the lower heating chamber 220. The cumulative opening time of the inflation valve is the cumulative duration during which the corresponding inflation valve is in an effectively open state within the leak detection time window. The controller determines the effective opening duration for each instance based on the inflation valve control output state and action feedback state. If the control output state and action feedback state are inconsistent, the action feedback times out, or no identifiable pressure change occurs during the opening period, the current cumulative opening time of the inflation valve is marked as invalid.

[0102] For different product specifications, air chamber volumes, and temperature stages, repeated pressure holding tests were conducted under the condition that the seal test was qualified and no simulated leakage was set to determine the normal opening time range; by simulating minor leakage and seal failure tests, the allowable compensated opening time range and the judgment conditions for serious leakage were determined.

[0103] Minor leaks are identified only within a time window when both the rate of change of the target pressure and the rate of change of the sheet temperature do not exceed the corresponding allowable leakage thresholds. A minor leak is determined to exist in the corresponding air chamber if the cumulative opening time of the inflation valve exceeds the normal opening time range but does not exceed the allowable compensated opening time range, and the pressure in the corresponding air chamber can be maintained within the pressure regulation range. If a minor leak exists in the corresponding air chamber, the pressure in the corresponding air chamber can still be maintained within the pressure regulation range, and the entry conditions for the pause heating state and the safety state are not met, the system enters a restricted heating state.

[0104] If the cumulative opening time of the inflation valve exceeds the allowable compensation opening time range and the pressure deviation of the corresponding air chamber continues to increase, or if the corresponding air chamber does not generate a recognizable pressure rise within the allowable response time after the inflation valve is opened, or if the sagging state of the corresponding sheet continues to deteriorate, it is determined that there is a serious leak in the corresponding air chamber.

[0105] When the rate of change of actual pressure in any air chamber exceeds the rapid leakage judgment value, the actual pressure exceeds the safe pressure range, the pressure deviation continues to expand, or any piece of material enters a stopped state, it is not subject to the leakage judgment time window and directly enters a safe state.

[0106] When both the first sheet 190 and the second sheet 200 reach their respective molding temperature ranges, both sheets are in a safe state, both pressure adjustment ranges are effective, and the actual pressure in both air chambers remains stable within their respective pressure adjustment ranges, and this condition is maintained continuously until the heating completion confirmation time is reached, the heating completion conditions are determined to be met. If any sheet enters a warning state, any air chamber pressure deviates from the pressure adjustment range, or any necessary data becomes invalid during the confirmation period, the heating completion confirmation time is recalculated.

[0107] The system enters a safe state when the maximum heating time has not yet been reached, the temperature of any sheet exceeds the upper limit of the molding temperature range, or any sheet reaches the allowable heat exposure time.

[0108] Once heating is complete, disconnect the heating power and remove the upper heating plate 140 and the lower heating plate 150. During the removal process, continue to acquire the sag status and temperature of the two sheets, the actual pressure of the two air chambers, and the position status of the two heating plates, and continue to perform the sag judgment of the two sheets.

[0109] During the retraction of the lower heating plate 150, the controller determines the current effective volume of the lower heating chamber 220 based on the position of the lower heating plate 150. The correspondence between the position of the lower heating plate 150 and the effective volume of the lower heating chamber 220 is determined based on the internal dimensions of the wellhead 110, the entry length of the lower heating plate 150, and the position calibration results, and is associated with and saved with the equipment configuration status.

[0110] The pressure control program adjusts the duration of the inflation valve or pressure relief valve's operation based on the current effective volume of the lower heating chamber 220, the actual pressure, and the allowable rate of pressure change. If the rate of pressure change caused by the movement of the lower heating plate 150 exceeds the corresponding allowable value, the withdrawal operation is paused, and the pressure in the lower heating chamber 220 is restored to the corresponding pressure regulation range. If the pressure cannot be restored within the specified time, the lateral entry channel seal is invalid, or any sheet material enters a stopped state, the system enters a safety state.

[0111] When both heating plates are fully removed and their positions are valid, the lateral entry channel is sealed by a sealing plate, both sheets are in a safe state, and the pressure data of both air chambers are valid and the actual pressure is stable, the molding preparation state can be entered.

[0112] Step four: The controller acquires the position status of the upper mold 160, lower mold 170, middle frame 120, and feeding mechanism 130, as well as the drooping status of the two sheets and the pressure of the two air chambers. When both heating plates are completely retracted, the feeding mechanism 130 exits the forming area, the middle frame 120, upper mold 160, and lower mold 170 are in positions corresponding to the current product specifications, both sheets are in a safe state, and the pressure data of the two air chambers is valid and there is no mechanical interference, the forming preparation conditions are determined to be met.

[0113] The controller adjusts the pressure of the two air chambers to the corresponding molding preparation pressure range. After the pressure of the two air chambers stabilizes, the lower mold 170 moves upward and the upper mold 160 moves downward. During the mold closing process, the corresponding pressure boundary and allowable pressure change rate are determined based on the position of the upper mold 160, the position of the lower mold 170, and the change in air chamber volume, thus completing the handover between the sheet support pressure and the molding pressure.

[0114] After the upper mold 160 and the lower mold 170 reach the mold closing position, the forming is completed by vacuum, positive pressure or a combination of vacuum and positive pressure, so that the two sheets are respectively attached to the corresponding mold surfaces and the sealing areas of the two sheets are pressed together.

[0115] After the molding time is reached and cooling is complete, release the molding pressure and open the mold. The middle frame 120 is not allowed to move upwards until the molding pressure drops to the allowable mold opening range.

[0116] After the mold is opened, the middle frame 120 moves upward, and the feeding mechanism 130 enters the equipment to receive the molded product. After the product receiving state of the feeding mechanism 130 is valid, the molded product is taken out of the equipment. When the molded product has been taken out, the lower mold 170 is in a safe position that allows the feeding mechanism 130 to enter, there are no foreign objects in the well opening 110, and there is no interference in the sheet placement path, the feeding mechanism 130 is allowed to transport the first sheet 190 of the next molding cycle.

[0117] Automatic cycling will stop if the formed product is not fully carried out, the product receiving status is invalid, the first sheet of the next sheet fails to be picked up at 190, or the feeding mechanism at 130 is in an abnormal position.

[0118] Example 2, this example is described. Figure 8 The process of parameter calibration and parameter version management for multi-specification sheets is shown.

[0119] Select the first sheet 190 and the second sheet 200 with different materials, sizes and thicknesses according to the processing range of the equipment, and calibrate them in the actual frame position, sheet clamping state, heating plate position and air circuit connection state.

[0120] The calibration content includes safe position, warning position, stop position, temperature stage, molding temperature range, sealing detection parameters, pressure boundary parameters for determining the first and second allowable ranges, pressure boundary parameters for determining the allowable pressure range and allowable following range of the lower heating chamber 220, allowable pressure change rate, pressure following trigger amount, maximum following delay, shortest state holding time and result validity time.

[0121] Pressure response calibration was performed at the initial, middle, and final stages of heating. Without putting the two sheets into a pre-heating state, the pressure in the inter-sheet air chamber 210 and the pressure in the lower heating chamber 220 were changed, and the sag status of the two sheets, the temperature of the two sheets, the pressure of the two air chambers, and the response time were recorded before and after the pressure change.

[0122] When calibrating the inter-sheet air cavity 210, the pressure of the lower heating cavity 220 is first maintained within a stable range corresponding to the current temperature stage. The pressure of the inter-sheet air cavity 210 is then changed in stages, and the sag changes of the second sheet 200 and the first sheet 190 are recorded simultaneously. Based on the pressure record corresponding to the second sheet 200 maintaining a safe state, candidate pressure boundaries for forming the first allowable range are determined. Based on the pressure record corresponding to the first sheet 190 maintaining a safe state, candidate pressure boundaries for forming the second allowable range are determined.

[0123] During the calibration of the lower heating chamber 220, the pressure of the inter-sheet air chamber 210 is maintained within a candidate range where the first and second allowable ranges can form a common range. The pressure of the lower heating chamber 220 is changed in stages, and the drooping state of the first sheet 190, the pressure difference between the two air chambers, and the pressure response time are recorded. Based on the records corresponding to the first sheet 190 maintaining a safe state, the pressure boundary parameters used to form the allowable pressure range and allowable following range of the lower heating chamber 220 are determined.

[0124] When any sheet enters the alert state, pressure changes in the current direction cease, and the current test record is marked as invalid. The actual pressure change should be greater than the pressure detection noise and valve dead zone. The single pressure change, holding time, and interval between adjacent tests are determined based on the air chamber volume, pressure detection resolution, valve response time, and sheet sag response speed.

[0125] At least multiple valid test records should be obtained for each calibration temperature stage. If the trend of the sheet sagging state changes is consistent across multiple valid records, and the differences between the pressure boundaries and pressure response times determined by each valid record do not exceed their respective consistency ranges determined based on the corresponding detection errors and repeated test fluctuations, then the valid records are deemed to meet the consistency requirements.

[0126] If the records do not meet the consistency requirements, increase the number of tests and check the sheet clamping status, temperature detection status, air cavity sealing status, and valve operation status. If a record that meets the consistency requirements still cannot be obtained after reaching the specified number of tests, or if the candidate pressure boundaries determined by different valid records do not have a common range, the current sheet combination calibration is determined to be a failure, production parameters are not generated, and the current combination is not allowed to enter the automatic production state.

[0127] When multiple valid records meet the consistency requirements and can form a common pressure range that simultaneously meets the safety distance requirements of two sheets, the candidate pressure upper and lower limits, allowable pressure difference boundaries, pressure correspondence, allowable pressure change rate, maximum following delay, shortest state holding time, and result validity time are determined based on the multiple records.

[0128] The pressure boundary parameters and timing parameters are associated with and saved along with product specifications, the materials, lengths, widths, and thicknesses of the two sheets, frame position, heating zone, detection position, air chamber volume, temperature range, sheet sag status, pressure change direction, and equipment configuration status to generate a valid parameter version. This valid parameter version saves the parameters used to form each allowable range, but does not directly save the pressure adjustment range formed in each control cycle during production.

[0129] The parameter records also include the allowed and prohibited pressure change directions of the two air chambers under different combinations of sheet sag states, the applicable temperature range, the effective state of the common safety direction, and the verification results, which can be retrieved when both sheets enter the stop state simultaneously.

[0130] When the product inspection results for multiple consecutive production cycles are qualified, neither sheet has entered a stopped state, neither air chamber has experienced any leakage abnormalities, and the test data are all valid, limited adjustments to the pressure boundary parameters and response time parameters are permitted within the safety boundaries determined by the calibration test.

[0131] Product inspection results are generated from at least one of the following: product dimension inspection results, sealing performance inspection results, appearance inspection results, or manual inspection results, and are saved in association with the corresponding production cycle, product specifications, and parameter versions. If no valid product inspection results are obtained, the current production cycle will not be used for parameter adjustments.

[0132] Limited adjustment settings include a single adjustment limit, a maximum number of consecutive adjustments, and a cumulative adjustment limit. Each adjustment limit is determined based on the minimum parameter change that will not cause the sheet to enter a warning state, detection errors, and fluctuations from repeated tests. The adjusted parameters are saved as a version to be verified. After passing verification throughout a complete production cycle, they are marked as a valid parameter version; if verification fails, the previous valid parameter version is restored.

[0133] When the sheet size exceeds the calibrated applicable range, the sheet shape changes the clamping boundary, the sheet material or thickness changes, the frame sealing part is repaired, the air circuit components are replaced, the pressure detection device 250 is replaced, or the heating plate position is adjusted, the original parameter version will stop automatic use and will be recalibrated.

[0134] Example 3 illustrates the control method when the first sheet 190 and the second sheet 200 are made of different materials or have different thicknesses.

[0135] The controller determines the temperature stage, forming temperature range, allowable heat exposure time, warning position, and stop position for each of the two sheets based on their material and thickness. The temperature stages of the two sheets can be different. Within the same control cycle, the controller uses the pressure boundary parameters corresponding to their respective temperature stages to perform sag judgments for the two sheets.

[0136] When the second sheet 200 first enters the softened state while the first sheet 190 remains in a safe state, the upper sheet sagging judgment raises the candidate lower limit of the pressure in the inter-sheet air cavity 210 based on the sagging state of the second sheet 200. Simultaneously, the lower sheet sagging judgment limits the candidate upper limit of the pressure in the inter-sheet air cavity 210 based on the state of the first sheet 190, and determines the pressure following range that the lower heating cavity 220 needs to meet, preventing the pressure in the inter-sheet air cavity 210 from rising and causing the first sheet 190 to continue approaching the lower heating plate 150.

[0137] When the first sheet 190 enters the softened state first, the lower sheet sagging judgment restricts the inter-sheet air cavity 210 from continuing to increase pressure and raises the lower limit of the pressure candidate range of the lower heating cavity 220. When the inter-sheet air cavity 210 needs to be pressurized to support the second sheet 200, the inter-sheet air cavity 210 is only allowed to continue to increase pressure if the lower heating cavity 220 can enter the allowable following range within the maximum following delay.

[0138] If one sheet has reached the molding temperature range while the other has not, reduce or maintain the heating power of the sheet that has reached the molding temperature range, and continue heating the other sheet. Enter a safe state when either sheet exceeds the upper limit of the molding temperature range or the allowable heat exposure time.

[0139] The heating plate can be removed when both sheets are simultaneously within their respective forming temperature ranges, both sheets are in a safe state, both pressure adjustment ranges are effective, and the actual pressure in both air chambers is stable. If the calibration test cannot establish a common time range that meets the above conditions, the current material and thickness combination will be determined as an unsuitable combination, and automatic production will not be initiated.

[0140] Example 4 illustrates the handling method under abnormal operating conditions.

[0141] If any pressure detection device 250, temperature detection device 240, or sheet sag detection device 230 has no output, exceeds its range, or the data times out, the relevant data will be marked as invalid. If some sheet sag detection points are invalid, but the remaining detection points can still determine the overall sag state of the corresponding sheet, the system enters a restricted heating state and is prohibited from returning to the normal heating state; if the overall sag state of any sheet, the pressure of any air chamber, or the effective temperature of any sheet cannot be determined, the system enters a safe state.

[0142] If, after any inflation valve is opened, the corresponding air chamber does not generate a identifiable pressure rise within the allowed response time, or if the actual pressure of any air chamber cannot be maintained within the corresponding pressure regulation range, the heating process will pause. The system will enter a safe state if both the inflation valve and the pressure relief valve simultaneously open, if the valve control status and action feedback are inconsistent, if the actual pressure of any air chamber exceeds the safe pressure range, if the safety valve activates, or if a serious leak occurs.

[0143] If any heating zone fails to generate the corresponding operating current or expected temperature rise after receiving a heating command, or if the temperature difference between adjacent heating zones exceeds the allowable value corresponding to the current specification, the corresponding heating zone will be marked as invalid. If a critical heating zone located in the product forming area or sheet sealing area is invalid, the heating power supply will be cut off and a safe state will be entered, without compensating the faulty heating zone by extending the total heating time.

[0144] If the feeding mechanism 130, middle frame 120, upper frame 121, lower frame 122, upper heating plate 140, lower heating plate 150, upper mold 160, or lower mold 170 fails to reach the target position within the corresponding maximum allowable time, or if their positions contradict each other, the relevant mechanism shall stop. If the heating plate position cannot be determined, the upper mold 160 and lower mold 170 move asynchronously, the mold closing pressure cannot be established, or the mold has not returned to a safe position, the system enters a safety state. When the mold is not in a safe position, the feeding mechanism 130 is not allowed to enter the equipment.

[0145] After the controller communication is interrupted or the power is restored, the mechanism action before the interruption is not directly restored. Instead, the heating plate, mold, middle frame 120, feeding mechanism 130, pressure of the two air chambers, temperature of the two sheets, and drooping status of the two sheets are reacquired.

[0146] Before heating begins, and when the sheet clamping status, frame position, and positions of each actuator are all valid, the sealing test of the two air chambers should be performed again. After passing the test, it is permissible to return to the pre-heating inspection state.

[0147] Once heating has begun, operation may resume under restricted heating only after the downtime, temperatures of both sheets, sagging status of both sheets, and pressure of both air chambers are all within the pre-calibrated recovery range of the current specifications, and after a data validity check has been completed again. The use of the current sheet must cease if any sheet has entered a stopped state, the heating time exceeds the allowable value, the sheet temperature exceeds the allowable heat exposure range, any air chamber experiences a serious leak, or the heating plate position cannot be confirmed.

[0148] The abnormal output should include at least the time of the abnormality, the current product specifications, the current heating status, the source of the abnormal data, the abnormal data, the data validity status, the executed state transitions, and the fault code. When multiple abnormalities exist, the final heating status is determined according to the priority of safe status, suspended heating status, restricted heating status, and normal heating status.

[0149] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for coordinated control of heating and feeding of multi-specification double-layer thermoforming sheets, characterized in that, The method includes: The drooping state and temperature of the first sheet and the second sheet during the heating process, the pressure of the air cavity between the sheets, and the pressure of the lower heating cavity are obtained; wherein, the air cavity between the sheets is formed between the first sheet and the second sheet, and the lower heating cavity is located below the wellhead and has the first sheet as its top boundary; When it is determined that the air chamber pressure needs to be adjusted based on the sag state and temperature of the first sheet and the second sheet, the air chamber pressure adjustment range between the sheets and the lower heating chamber pressure adjustment range are determined based on the sag state, the temperature, the air chamber pressure between the sheets and the lower heating chamber pressure. Under the current heating state, the pressure of the air chamber between the sheets is adjusted according to the pressure adjustment range of the air chamber between the sheets, and the pressure of the lower heating chamber is adjusted according to the pressure adjustment range of the lower heating chamber.

2. The method for coordinated control of heating and feeding of multi-specification double-layer thermoforming sheets according to claim 1, characterized in that, The determination of the pressure adjustment range of the inter-sheet air chamber and the lower heating chamber includes: Within the same control cycle, based on the sag state and temperature of the second sheet, the air cavity pressure between the sheets, and the direction of change of the air cavity pressure between the sheets, a first allowable range of the air cavity pressure between the sheets is determined; Within the same control cycle, based on the sag state and temperature of the first sheet, the inter-sheet air chamber pressure, the lower heating chamber pressure, and the respective change directions of the inter-sheet air chamber pressure and the lower heating chamber pressure, a second allowable range of the inter-sheet air chamber pressure, an allowable range of the lower heating chamber pressure, and an allowable following range of the lower heating chamber pressure relative to the inter-sheet air chamber pressure are determined. The two determination processes are executed in parallel based on the input data of the same control cycle, and neither determination process uses the output of the other determination process as input.

3. The method for coordinated control of heating and feeding of multi-specification double-layer thermoforming sheets according to claim 2, characterized in that, The determination of the pressure adjustment range of the inter-sheet air chamber and the lower heating chamber includes: The overlapping range of the first allowable range and the second allowable range is defined as the pressure adjustment range of the air cavity between the sheets; Based on the current pressure of the air cavity between the sheets, a pressure sub-range that satisfies the allowable following range is determined from the allowable range of the lower heating chamber pressure, and the pressure sub-range is determined as the lower heating chamber pressure adjustment range; When the first allowable range and the second allowable range do not overlap, the air chamber pressure adjustment range between the sheets is marked as invalid; If there is no pressure sub-interval that satisfies the allowable following range within the allowable range of the lower heating chamber pressure, the lower heating chamber pressure adjustment range is marked as invalid. Normal heating is prohibited if any of the pressure adjustment ranges are invalid.

4. The method for coordinated control of heating and feeding of multi-specification double-layer thermoforming sheets according to claim 3, characterized in that, The method further includes: Based on the drooping state and temperature of the first sheet and the second sheet, the pressure of the air cavity between the sheets and the pressure of the lower heating cavity, the allowable pressure change rate of the air cavity between the sheets and the lower heating cavity in the pressure increase direction and the pressure decrease direction, and the maximum following delay, the shortest state holding time, the result validity time and the allowable heating state to be entered relative to the pressure of the lower heating cavity with respect to the pressure of the air cavity between the sheets are determined. The pressure adjustment range of the inter-sheet air chamber, the pressure adjustment range of the lower heating chamber, the allowable pressure change rate of each of the two air chambers in the pressure increase and decrease directions, the maximum following delay, the shortest state holding time, the result validity time, and the allowed heating state are used as the operating boundaries of the pressure control program. Within the operating boundary, the pressure control program controls the inflation valve and pressure relief valve corresponding to the inter-sheet air chamber based on the relationship between the actual pressure of the inter-sheet air chamber and the pressure adjustment range of the inter-sheet air chamber. It also controls the inflation valve and pressure relief valve corresponding to the lower heating chamber based on the relationship between the actual pressure of the lower heating chamber and the pressure adjustment range of the lower heating chamber. The inflation valve and pressure relief valve corresponding to the same air chamber are interlocked, and only one valve is allowed to be open at any given time.

5. The method for coordinated control of heating and feeding of multi-specification double-layer thermoformed sheets according to claim 4, characterized in that, The heating states include normal heating state, limited heating state, paused heating state, and safe state; The necessary data for determining the heating state includes the drooping state and temperature of the first sheet and the second sheet respectively, the air chamber pressure between the sheets, and the lower heating chamber pressure; When all necessary data are valid, the sagging state of the first sheet and the second sheet has not reached the warning state, both pressure adjustment ranges are valid, the actual pressure of the two air chambers is within their respective pressure adjustment ranges, and the actual following delay of the lower heating chamber pressure relative to the air chamber pressure between the sheets does not exceed the maximum following delay, the normal heating state is entered. If the conditions for entering the pause heating state and the safety state are not met, the restricted heating state shall be entered when any of the following conditions are met: the sagging state of one of the first sheet and the second sheet is in the warning state, the sagging state of the other sheet is not in the warning state, and both pressure adjustment ranges are effective; there is a slight leak in any air chamber, and the actual pressure of the corresponding air chamber can be maintained within the corresponding pressure adjustment range. If the conditions for entering the safety state are not met, when both the first sheet and the second sheet are in a warning state, or when the actual following delay exceeds the maximum following delay, the heating pause state is entered. The safe state is entered when any sheet is in a stopped drooping state, any of the pressure adjustment ranges is invalid, the actual pressure of any air chamber exceeds the corresponding safe pressure range, or any of the necessary data is invalid.

6. The method for coordinated control of heating and feeding of multi-specification double-layer thermoformed sheets according to claim 5, characterized in that, The priority of the safe state, the paused heating state, the restricted heating state, and the normal heating state decreases in that order, and only one heating state is allowed to be active at any given time. When the conditions for entering the safety state are met under any heating state, the system enters the safety state. Under the restricted heating state, all necessary data are valid, the sagging state of the first sheet and the second sheet is restored to a state that does not reach the warning state, both pressure adjustment ranges are valid, the actual pressure of the two air chambers enters their respective pressure adjustment ranges, the actual following delay does not exceed the maximum following delay, there is no leakage abnormality, and when the minimum state holding time is continuously reached, the normal heating state is returned. When the restricted heating state is not met and the conditions for entering the safety state are not met, the heating pause state is entered when any of the following conditions are met: the first sheet and the second sheet are both in the alert state, the actual following delay exceeds the maximum following delay, or the restricted heating state reaches the corresponding longest allowable time. In the paused heating state, all necessary data are valid, the sagging state of the first sheet and the second sheet is restored to a state that has not reached the warning state, both pressure adjustment ranges are valid, the actual pressure of the two air chambers enters their respective pressure adjustment ranges, and the actual following delay does not exceed the maximum following delay and continues to reach the shortest state holding time, then the restricted heating state is entered. When the pause heating state reaches the corresponding maximum allowable time and the conditions for entering the restricted heating state are not met, the safe state is entered. The shortest state holding time does not limit the transition to a higher priority heating state, and the safe state does not automatically return to the normal heating state.

7. The method for coordinated control of heating and feeding of multi-specification double-layer thermoforming sheets according to claim 1, characterized in that, Before acquiring the drooping state, the temperature, the inter-sheet air cavity pressure, and the lower heating cavity pressure, the method further includes: With the upper and lower frames locked, the first sheet is conveyed between the wellhead and the lower frame, and the upper and lower frames are moved synchronously to clamp the first sheet between the wellhead and the lower frame. Release the locking relationship between the upper frame and the lower frame, allowing the upper frame to move relative to the lower frame, conveying the second sheet between the upper frame and the lower frame, and moving the upper frame towards the lower frame to clamp the second sheet between the upper frame and the lower frame; The air cavity between the first sheet and the second sheet is subjected to a sealing test, and the upper heating plate and the lower heating plate are allowed to enter after the air cavity between the sheets passes the sealing test.

8. The method for linkage control of heating and feeding of multi-specification double-layer thermoforming sheets according to claim 7, characterized in that, After the air cavity between the sheets passes the sealing test, the upper heating plate is moved above the second sheet, and the lower heating plate is moved into the lower heating cavity. After the upper heating plate and the lower heating plate reach the heating position, the lower heating cavity is tested for sealing, and heating begins after the lower heating cavity passes the sealing test. When both the first sheet and the second sheet reach their respective molding temperature ranges, the sagging state of both the first sheet and the second sheet has not reached the warning state, both pressure adjustment ranges are effective, the actual pressure of both air chambers is stable within their respective pressure adjustment ranges, and the heating completion confirmation time is reached, the upper heating plate and the lower heating plate are controlled to be withdrawn. During the removal of the upper heating plate and the lower heating plate, the drooping state and temperature of the first sheet and the second sheet, the air cavity pressure between the sheets and the lower heating cavity pressure are continuously acquired, and the corresponding air cavity pressure is continuously adjusted according to the air cavity pressure adjustment range between the sheets and the lower heating cavity pressure adjustment range. When the upper heating plate and the lower heating plate are completely retracted and their positions are valid, the sagging of the first sheet and the second sheet has not reached the warning state, and the pressure data of the two air chambers are valid and the actual pressure is stable, the molding preparation state is allowed.

9. The method for linkage control of heating and feeding of multi-specification double-layer thermoforming sheets according to claim 4, characterized in that, The method further includes: Based on the product specifications, the materials, lengths, widths, and thicknesses of the first and second sheets, as well as the volumes of the air chambers between the sheets and the lower heating chamber, the corresponding valid parameters are recorded. The effective parameter record includes molding temperature range, allowable sag range, sealing detection parameters, pressure boundary parameters for determining the first allowable range and the second allowable range, pressure boundary parameters for determining the allowable range of the lower heating chamber pressure and the allowable following range, allowable pressure change rate, maximum following delay, shortest state holding time, and result validity time. When there are no corresponding valid parameter records for the combination of the current product specifications, the material, length, width, and thickness of the first and second sheets, and the volume of the air cavity between the sheets and the lower heating cavity, the pressure of the air cavity between the sheets and the pressure of the lower heating cavity are changed at the beginning, middle, and end of the sheet heating process, respectively, without causing the first and second sheets to reach their respective warning positions. The sag state and temperature of the first and second sheets, the pressure of the air cavity between the sheets, the pressure of the lower heating cavity, and the response time before and after the pressure change are recorded to obtain multiple valid records. The consistency requirement is that the trend of the sheet sagging state changes is consistent in multiple valid records, and the differences between the pressure boundaries and the differences between the pressure response times determined in multiple valid records do not exceed their respective consistency ranges determined based on the corresponding detection errors and repeated test fluctuations. When multiple valid records meet the consistency requirement, the first allowable range and the second allowable range determined based on multiple valid records overlap, and there is a pressure sub-interval in the allowable range of the lower heating chamber pressure that meets the allowable following range, the pressure boundary parameter, the allowable pressure change rate, the maximum following delay, the shortest state holding time, and the result validity time are determined based on multiple valid records. The determined parameters are associated with the product specifications, the material, length, width, and thickness of the first sheet and the second sheet, and the volume of the air cavity between the sheets and the lower heating chamber, and a valid parameter version is generated. If multiple valid records fail to meet the consistency requirements, the first allowable range and the second allowable range do not overlap, or there is no pressure sub-interval in the allowable range of the lower heating chamber pressure that meets the allowable following range, the current parameter calibration result will be marked as invalid, and automatic production using the current sheet combination will be prohibited.

10. A controller for a double-layer sheet thermoforming equipment, characterized in that, Includes processor, memory, and input / output interfaces; The memory is used to store control programs, product specifications, sheet parameters, air cavity parameters, calibration parameters, and parameter versions; The input / output interface is used to acquire the drooping state and temperature of the first sheet and the second sheet in the double-layer sheet vacuum forming equipment, the pressure of the inter-sheet air cavity formed between the first sheet and the second sheet, and the pressure of the lower heating cavity located below the first sheet; The input / output interface is also used to acquire the position of the feeding mechanism and the sheet arrival status, the position and locking status of the upper and lower frames, the position status of the upper heating plate and the lower heating plate, the sealing status of the lateral entry channel of the lower heating plate, the sealing status of the air chamber between the sheets and the lower heating chamber, the operation status of the inflation valve and the pressure relief valve corresponding to each of the two air chambers, and the position status of the upper and lower molds. The input / output interface is also used to acquire product specifications, the material, length, width and thickness of the first sheet and the second sheet, as well as the volume of the air cavity between the sheets and the lower heating cavity, and to output air cavity pressure control signal, heating control signal and actuator action control signal; The processor is used to execute the control program to implement the multi-specification double-layer thermoforming sheet heating and feeding linkage control method as described in any one of claims 1 to 9.

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