A compression molding machine for soft mold molding

Abstract

This invention discloses a compression molding machine for forming soft molds, belonging to the technical field of soft mold forming equipment. The compression molding machine includes a frame, an upper mold assembly, a lower mold assembly, an elastic support unit, a shrinkage sensing component, a control unit, and a stroke limiter. The mold body of the lower mold assembly is made of soft material and cooperates with the upper mold assembly to form a closed mold cavity. The elastic support unit includes a hydraulic cylinder, a hydraulic pump, an oil tank, and an overflow valve; the piston rod of the hydraulic cylinder is connected to the lower mold assembly. The shrinkage sensing component includes a pressure sensor, a laser displacement sensor, and a temperature sensor. The control unit decouples and performs multi-parameter judgment based on pressure, displacement, and temperature signals to identify the actual shrinkage state of the soft lower mold and controls the hydraulic pump to dynamically adjust the support force, causing the lower mold assembly to press the material upwards to maintain fit. The stroke limiter cooperates with a fixed reference to prevent the piston rod from overextending. This invention can improve the molding accuracy and consistency of complex textured products.

Description

Technical Field

[0001] This invention relates to the field of soft mold forming equipment technology, and more specifically, to a compression molding machine for soft mold forming. Background Technology

[0002] In the molding and processing of rheological materials, soft molds are widely used in the compression molding of products with complex surface textures due to their excellent elastic deformation capability and ease of demolding. At the same time, they can achieve a tight fit between the mold cavity and the material through their own elastic deformation, effectively reducing the risk of collision damage to fragile products during demolding, while also reducing the processing difficulty and cost of complex textured mold cavities.

[0003] However, existing soft molds have the properties of high thermal expansion coefficient and low thermal conductivity. The lower mold needs to exchange heat with the material for a long time due to bearing the weight of the material, and its cooling rate is much faster than that of the upper mold. This leads to an imbalance in the shrinkage amount and rhythm of the upper and lower molds. The rebound force of the lower mold on the material continues to decrease, and the material collapses downward, causing problems such as product flattening and distortion, and blurred texture on the side of the upper mold.

[0004] Therefore, a new solution is needed to address this problem. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to overcome the defects of existing soft mold pressing molding machines, such as uneven cooling and thermal shrinkage leading to product distortion, delayed support force adjustment, and low level of intelligence. The invention provides an intelligent pressing molding machine that can predict mold shrinkage trends in real time, dynamically adjust support force, and accurately monitor the bonding state, thereby achieving high-precision molding of complex textured products, reducing manual intervention, and improving production efficiency and product consistency.

[0006] This invention achieves the above-mentioned objective through the following technical solution: a compression molding machine for forming soft molds, comprising:

[0007] frame;

[0008] The upper mold assembly is vertically mounted on the upper part of the frame;

[0009] The lower mold assembly is located at the bottom of the frame. Its mold body is made of soft material and is used to carry the rheological material. It cooperates with the upper mold assembly to form a closed mold cavity to accommodate the rheological material.

[0010] The elastic support unit includes a hydraulic cylinder, a hydraulic pump, an oil tank, and an overflow valve. The bottom end of the cylinder body is fixed to the frame, and the top end of the piston rod of the hydraulic cylinder is fixedly connected to the bottom of the lower mold assembly. The hydraulic pump is connected to the hydraulic cylinder through an oil circuit, and the oil tank is connected to the hydraulic pump through an oil circuit. The overflow valve is set on the oil circuit between the hydraulic pump and the hydraulic cylinder to suppress oil circuit pressure fluctuations.

[0011] A shrinkage sensing component, associated with the lower mold assembly, includes a pressure sensor, a displacement sensor, and a temperature sensor. Multiple pressure sensors are distributed along the connection surface between the lower mold assembly and the elastic support unit to detect the pressure signal transmitted from the lower mold assembly to the elastic support unit. The fixed end of the displacement sensor is mounted on the frame, and its detection end is positioned corresponding to the lower mold assembly to detect the vertical displacement signal of the lower mold assembly. The temperature sensor is attached to the edge of the mold cavity of the lower mold assembly to detect the temperature signal of the lower mold assembly.

[0012] The control unit is electrically connected to a pressure sensor, a displacement sensor, a temperature sensor, and a hydraulic pump. The control unit is configured to: perform force balance calculations based on the pressure signal and the current support force output value of the elastic support unit to obtain the rebound force of the soft material on the material; perform compensation calculations based on the vertical displacement signal and the extension amount of the cylinder piston rod to obtain the shrinkage displacement of the soft material due to cooling; determine a true shrinkage state when the temperature drop ΔT ≥ 3℃, the shrinkage displacement ΔL ≥ 0.05mm, and the decrease in rebound force ΔF reaches a preset rebound force threshold; and send a control command to the hydraulic pump to extend the piston rod of the cylinder by the compensation amount, pushing the lower mold assembly upwards to squeeze the material and maintain the material's fit with the mold cavity of the upper mold assembly.

[0013] The stroke limit component is fixed to the bottom of the piston rod and has a built-in displacement trigger switch;

[0014] A fixed reference is set on the inner wall of the cylinder and cooperates with the displacement trigger switch;

[0015] When the extension or retraction of the piston rod reaches a preset value that matches the maximum shrinkage of the soft material, the displacement trigger switch is aligned with the fixed reference, triggering a limit signal. The control unit then controls the hydraulic pump to stop supplying oil based on the limit signal.

[0016] The present invention is further configured such that: five pressure sensors are provided, respectively arranged at the four corners and the center of the bottom of the lower mold assembly, and each pressure sensor is provided with a rigid conductive pad on the connection surface with the lower mold assembly.

[0017] The invention is further configured such that: the displacement sensor is a laser displacement sensor, its fixed end is rigidly connected to the frame through a bracket, the detection end is vertically aligned with the side of the mold base of the lower mold assembly, and a high reflectivity target is provided on the side of the mold base.

[0018] The present invention is further configured such that: the preset rebound force threshold is set according to the hardness of the soft material; when the soft material is low-hardness silicone, the preset rebound force threshold is 0.8%-1%;

[0019] When the soft material is high-hardness rubber, the preset rebound force threshold is 3%.

[0020] The present invention is further configured to include a cooling component, wherein the cooling component is a built-in spiral water channel, which is respectively opened in the mold core of the upper mold component and the mold base of the lower mold component. The water inlet end of the cooling component is connected to a proportional temperature control valve, which is electrically connected to the control unit and dynamically adjusts the cooling water flow rate according to the detection value of the contraction sensing component.

[0021] The present invention is further configured to include a guiding mechanism, the guiding mechanism comprising a guide rail fixed vertically to the frame, and a slider fixed to the side of the lower mold assembly and slidingly engaged with the guide rail.

[0022] The present invention is further configured such that: the control unit includes a primary link, a secondary link, a tertiary link, and a main control module;

[0023] The primary link is used to receive the analog signal output by the pressure sensor, the digital signal output by the displacement sensor, and the resistance signal output by the temperature sensor.

[0024] The secondary link is used to amplify and filter analog signals, isolate and convert digital signals, and perform constant current source conversion and analog-to-digital conversion on resistance signals.

[0025] The three-level link is used to transmit the conditioned signal to the main control module.

[0026] The present invention is further configured such that the main control module is also configured to perform validity screening on the received signals: when the signal fluctuation amplitude of any pressure sensor exceeds 5% within 100ms, the data of the pressure sensor is discarded and replaced with the average value of other pressure sensors at the same location;

[0027] When the displacement change of the displacement sensor does not match the temperature drop of the temperature sensor, it is determined to be a signal distortion and the backup displacement sensor is activated.

[0028] When the deviation of the detection values ​​of multiple temperature sensors exceeds 2°C, it is determined to be a local temperature anomaly, and the pressure signal is given priority as the basis for judging the rebound force.

[0029] The present invention is further configured such that: the control unit also integrates a data storage module, the data storage module is used to record the springback force change curve, shrinkage displacement curve and support force control curve of each molding process, and supports data export via USB interface or Ethernet interface.

[0030] The present invention is further configured such that: the upper mold assembly is driven to lift by a servo electric cylinder, the servo electric cylinder being fixed to the top of the frame and electrically connected to the control unit.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] By using multi-parameter detection from pressure sensors, laser displacement sensors, and temperature sensors, combined with force balance calculations and displacement compensation calculations, the true shrinkage state of the soft lower die can be identified more accurately, reducing misjudgments from a single sensor. Dynamic adjustment of the support force via hydraulic pumps and cylinders can push the lower die assembly upwards to extrude the material, ensuring the material remains in contact with the upper die cavity during cooling and shaping. Stroke limiters and fixed references prevent excessive piston rod extension. Overflow valves, guide mechanisms, and cooling components improve equipment operational stability and molding consistency. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is a structural diagram of the upper mold assembly, lower mold assembly, and elastic support unit. Figure 1 ;

[0035] Figure 3 This is a structural diagram of the upper mold assembly, lower mold assembly, and elastic support unit. Figure 2 ;

[0036] Figure 4 A structural schematic diagram of the hydraulic cylinder and stroke limiting component;

[0037] Figure 5 This is a schematic diagram of the built-in spiral water channel.

[0038] Figure 6 This is the overall block diagram of the control system, where solid arrows represent electrical connections, control connections, or signal connections, and dashed arrows represent the correlation and detection relationship between the lower mold assembly and the sensor;

[0039] Figure 7 This is a flowchart of the main control system for compression molding, used to show the complete process from preheating, mold closing, data acquisition, judgment, compensation to mold opening and part removal;

[0040] Figure 8This is a flowchart for real contraction judgment and dynamic compensation of support force, used to demonstrate pressure / displacement / temperature decoupling, multi-parameter judgment, hydraulic pump control and limit stop logic.

[0041] Reference numerals: 1. Frame; 2. Upper mold assembly; 3. Lower mold assembly; 4. Elastic support unit; 5. Pressure sensor; 6. Displacement sensor; 7. Temperature sensor; 8. Rigid conductive pad; 9. High reflectivity target; 10. Hydraulic cylinder; 11. Stroke limit component; 12. Displacement trigger switch; 13. Fixed reference; 14. Built-in spiral water channel; 15. Proportional temperature control valve; 16. Guide rail; 17. Slider; 18. Servo electric cylinder; 19. Hydraulic pump; 20. Oil tank; 21. Overflow valve; 22. Control unit; 23. Data storage module; 24. Primary link; 25. Secondary link; 26. Tertiary link; 27. Main control module. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of the present invention.

[0043] Example:

[0044] like Figures 1-5 As shown, a compression molding machine for forming soft molds includes a frame 1, an upper mold assembly 2, a lower mold assembly 3, an elastic support unit 4, a shrinkage sensing assembly, a control unit 22, and a stroke limiter 11.

[0045] A servo electric cylinder 18 is mounted on the frame 1 and is electrically connected to the control unit 22. The upper mold assembly 2 is vertically and flexibly mounted on the upper part of the frame 1 via the servo electric cylinder 18. The lower mold assembly 3 is located at the lower part of the frame 1, and its mold body is made of a soft material, such as silicone or rubber. The lower mold assembly 3 is used to hold the rheological material and cooperates with the upper mold assembly 2 to form a closed mold cavity for accommodating the rheological material.

[0046] The elastic support unit 4 includes a hydraulic cylinder 10, a hydraulic pump 19, an oil tank 20, and a relief valve 21. The bottom end of the cylinder body of the hydraulic cylinder 10 is fixed to the support platform of the frame 1 via a flange, and a nitrile rubber shock-absorbing pad can be installed between the flange and the frame 1. The top end of the piston rod of the hydraulic cylinder 10 is fixedly connected to the connecting seat at the bottom of the lower mold assembly 3. The hydraulic pump 19 is connected to the hydraulic cylinder 10 via a high-pressure oil circuit, and the oil tank 20 is connected to the hydraulic pump 19 via an oil circuit. The relief valve 21 is located on the oil circuit between the hydraulic pump 19 and the hydraulic cylinder 10, and is used to release pressure when the oil circuit pressure exceeds a preset value, thereby suppressing oil circuit pressure fluctuations. The hydraulic pump 19 is electrically connected to the control unit 22, which can adjust the supporting force of the elastic support unit 4 by controlling the flow rate and pressure of the hydraulic pump 19.

[0047] The contraction sensing component is associated with the lower mold assembly 3 and includes a pressure sensor 5, a displacement sensor 6, and a temperature sensor 7. Five pressure sensors 5 are arranged at the four corners and the center of the bottom of the lower mold assembly 3. A rigid conductive pad 8, which can be a 0.05mm thick copper pad, is provided between each pressure sensor 5 and the lower mold assembly 3. The pressure sensors 5 are used to detect the pressure signal transmitted from the lower mold assembly 3 to the elastic support unit 4. Since the supporting force of the elastic support unit 4 also acts on the pressure sensors 5, the control unit 22 performs force balance calculations based on the pressure signal detected by the pressure sensors 5 and the supporting force output value corresponding to the current output pressure of the hydraulic pump 19, thereby obtaining the rebound force of the soft material on the material. For example, the control unit 22 can calculate the current supporting force based on the output pressure of the hydraulic pump 19 and the effective area of ​​the cylinder 10, and subtract this supporting force component from the resultant force detected by the pressure sensors 5 to obtain the rebound force of the soft material on the material. The multi-point arrangement of the five pressure sensors 5 reduces detection deviations caused by local stress concentration.

[0048] The displacement sensor 6 is a laser displacement sensor. Its fixed end is rigidly connected to the frame 1 via a bracket, and its detection end is vertically aligned with the side of the mold base of the lower mold assembly 3. A high-reflectivity target 9 is provided on the side of the mold base, which can be a polished stainless steel part. The displacement sensor 6 is used to detect the vertical displacement signal of the lower mold assembly 3. Since the lower mold assembly 3 will generate vertical displacement when it cools and contracts, and the elastic support unit 4 will also generate vertical displacement when pushing the lower mold assembly 3 upward, the control unit 22 compensates for the detection value of the displacement sensor 6 based on the extension of the piston rod of the hydraulic cylinder 10, deducts the support compensation displacement, and obtains the amount of shrinkage displacement of the soft material caused by cooling.

[0049] Temperature sensor 7 is attached to the edge of the mold cavity of lower mold assembly 3 and can be arranged close to the material area. Two to four temperature sensors 7 can be set to detect the temperature signal of lower mold assembly 3. Temperature sensor 7 can be a surface-mount platinum resistance temperature sensor with a temperature measurement accuracy of ±0.1℃ and a range of -20℃ to 200℃.

[0050] The control unit 22 is electrically connected to the pressure sensor 5, displacement sensor 6, temperature sensor 7, and hydraulic pump 19. The control unit 22 has pre-stored temperature-shrinkage-resilience correlation rules. These rules can be expressed as threshold tables, mapping tables, or empirical formulas, and can be calibrated through a limited number of tests based on the material, hardness, and material type of the soft mold. After receiving pressure signals, vertical displacement signals, and temperature signals, the control unit 22 performs validity screening and determines the true shrinkage.

[0051] Specifically, the control unit 22 may include a primary link 24, a secondary link 25, a tertiary link 26, and a main control module 27. It can obtain the resilience force and cooling contraction displacement of the soft material through force balance calculation and displacement compensation calculation. The primary link 24 receives the 4-20mA analog signal output from the pressure sensor 5, the RS485 digital signal output from the displacement sensor 6, and the PT100 resistance signal output from the temperature sensor 7. The secondary link 25 performs differential amplification and low-pass filtering on the analog signal, isolated RS485 to CAN conversion on the digital signal, and constant current source conversion and 16-bit ADC analog-to-digital conversion on the resistance signal. The tertiary link 26 transmits the conditioned signal to the main control module 27. Pressure and temperature signals can be transmitted via shielded twisted-pair cable, while displacement signals can be transmitted via CAN bus cable. For critical pressure signals, dual independent channels can be used for transmission.

[0052] like Figure 6As shown, the control system includes a sensing layer, a control layer, an execution layer, and a controlled object. The sensing layer includes a pressure sensor 5, a displacement sensor 6, and a temperature sensor 7. The control layer includes a control unit 22, which contains a primary link 24, a secondary link 25, a tertiary link 26, a main control module 27, and a data storage module 23. The execution layer includes a servo electric cylinder 18, a hydraulic pump 19, an overflow valve 21, an oil tank 20, and a proportional temperature control valve 15. The controlled object includes an upper mold assembly 2, a lower mold assembly 3, an elastic support unit 4, a hydraulic cylinder 10, a built-in spiral water channel 14, and a frame 1. The pressure sensor 5, displacement sensor 6, and temperature sensor 7 are connected to the primary link 24 via signal lines. The primary link 24 connects to the secondary link 25, the secondary link 25 connects to the tertiary link 26, and the tertiary link 26 connects to the main control module 27. The main control module 27 is electrically connected to the data storage module 23, the servo electric cylinder 18, the hydraulic pump 19, and the proportional temperature control valve 15. Hydraulic pump 19 is connected to oil tank 20, overflow valve 21, and cylinder 10 via oil circuits. Cylinder 10 drives elastic support unit 4, which is connected to lower mold assembly 3. Proportional temperature control valve 15 is connected to built-in spiral water channel 14, which is installed in both upper mold assembly 2 and lower mold assembly 3. Pressure sensor 5, displacement sensor 6, and temperature sensor 7 are associated with lower mold assembly 3. Frame 1 supports servo electric cylinder 18 and elastic support unit 4.

[0053] Thus, the control unit 22 can receive and process signals from the pressure sensor 5, displacement sensor 6 and temperature sensor 7 through the first-level link 24, the second-level link 25 and the third-level link 26, and control the servo electric cylinder 18, hydraulic pump 19 and proportional temperature control valve 15 through the main control module 27, forming a closed-loop control of perception, judgment, execution and feedback.

[0054] The main control module 27 filters the received signals for validity. For example, if the signal fluctuation amplitude of a pressure sensor 5 exceeds 5% within 100ms, it is determined to be an abnormal signal, the data of that pressure sensor 5 is discarded, and the average value of other pressure sensors 5 at the same location is used instead. When the displacement change detected by the displacement sensor 6 does not match the temperature drop detected by the temperature sensor 7, for example, a temperature drop of 5°C corresponds to a theoretical contraction of 0.2mm, but the actual displacement change exceeds 0.5mm, it is determined to be a signal distortion, and the backup displacement sensor 6 is activated. When the detection values ​​of multiple temperature sensors 7 deviate by more than 2°C, it is determined to be a local temperature anomaly. The pressure signal is prioritized as the basis for judging the rebound force, and a cooling system fault warning may be triggered.

[0055] When the temperature sensor 7 detects that the temperature drop ΔT of the lower mold is ≥ 3°C, the contraction displacement ΔL obtained by the displacement sensor 6 after compensation calculation is ≥ 0.05 mm, and the rebound force decrease range ΔF obtained by the pressure sensor 5 after calculation reaches the preset rebound force threshold, the control unit 22 determines that a real contraction state is present. The preset rebound force threshold can be set according to the hardness of the soft material. For example, for low-hardness silica gel, the preset rebound force threshold may be 0.8%-1%; for high-hardness rubber, the preset rebound force threshold may be 3%. If only the temperature drops while the displacement and rebound force do not change, or only a single parameter changes, the control unit 22 may determine that it is an interference signal and will not trigger the support force compensation.

[0056] When a real contraction state is determined, the control unit 22 sends a regulation instruction to the hydraulic pump 19. In response to the instruction, the hydraulic pump 19 increases the oil circuit pressure to extend the piston rod of the oil cylinder 10 by a compensation amount. The piston rod pushes the lower mold assembly 3 to squeeze the material upward, so as to maintain the fit between the material and the mold cavity of the upper mold assembly 2. The overflow valve 21 synchronously suppresses the oil circuit pressure fluctuation, and improves the stability of the support force.

[0057] The stroke limiter 11 is fixed to the bottom of the piston rod of the oil cylinder 10, and a displacement trigger switch 12 is arranged inside. The fixed reference 13 is disposed on the inner wall of the oil cylinder 10 and cooperates with the displacement trigger switch 12. The displacement trigger switch 12 may be a Hall-type displacement trigger switch, and the fixed reference 13 may be a magnetic ring. When the expansion and contraction amount of the piston rod reaches a preset value adapted to the maximum contraction amount of the soft material, for example, the preset value is 1.5 mm to 2 mm, the displacement trigger switch 12 is aligned with the fixed reference 13, and sends a limit signal to the control unit 22 after detecting a magnetic field signal. The control unit 22 controls the hydraulic pump 19 to stop supplying oil according to the limit signal, so that the elastic support unit 4 maintains the current support force, and prevents the piston rod from extending excessively to cause mold damage or material overpressure.

[0058] The compression molding machine may further include a cooling assembly. The cooling assembly is a built-in spiral water channel 14, which is respectively opened in the mold core of the upper mold assembly 2 and the mold base of the lower mold assembly 3. The water inlet end of the built-in spiral water channel 14 is connected with a proportional temperature control valve 15, and the proportional temperature control valve 15 is electrically connected to the control unit 22. The control unit 22 can dynamically adjust the opening of the proportional temperature control valve 15 according to the detection value of the temperature sensor 7, so as to adjust the flow rate of cooling water. For example, when the temperature is higher than the preset value, the flow rate is increased, and when the temperature is lower than the preset value, the flow rate is decreased, so as to realize the coordinated regulation of temperature and support force.

[0059] The compression molding machine may further include a guide mechanism. The guide mechanism includes a guide rail 16 fixed to the frame 1 along the vertical direction, and a sliding block 17 fixed to the side surface of the lower mold assembly 3. The sliding block 17 is in sliding fit with the guide rail 16, so that the lower mold assembly 3 moves substantially in the vertical direction when driven by the elastic support unit 4, reducing horizontal offset.

[0060] The control unit 22 also integrates a data storage module 23. The data storage module 23 is used to record the springback force change curve, shrinkage displacement curve, and support force control curve during each molding process, and supports data export via USB interface or Ethernet interface for production quality traceability and process parameter optimization.

[0061] Working principle:

[0062] The control unit 22 loads the parameter template corresponding to the current production task, such as the soft mold material, material type, preset support force threshold, cooling temperature curve, etc., and completes the initialization of the temperature-shrinkage-rebound force association rules.

[0063] like Figure 7 As shown, the compression molding main control flow includes:

[0064] S1. Start and initialize; control unit 22 loads current production task parameters.

[0065] S2. Lower mold preheating: Control unit 22 controls proportional temperature control valve 15 to introduce cooling water or preheating medium, and temperature sensor 7 detects the temperature of lower mold assembly 3.

[0066] S3. Determine if the preheating meets the standard. If not, return to S2; if yes, proceed to S4.

[0067] S4. Inject rheotropic material;

[0068] S5. The upper mold moves downward to close the mold. The control unit 22 controls the servo electric cylinder 18 to drive the upper mold assembly 2 downward to form a closed mold cavity with the lower mold assembly 3.

[0069] S6. Elastic support initialization: Control unit 22 controls hydraulic pump 19 to supply oil to cylinder 10, and elastic support unit 4 outputs initial support force.

[0070] S7. Multi-sensor acquisition: pressure sensor 5 acquires pressure signals, displacement sensor 6 acquires vertical displacement signals, and temperature sensor 7 acquires temperature signals.

[0071] S8, Signal conditioning and transmission: The signal is transmitted to the main control module 27 via primary link 24, secondary link 25, and tertiary link 26.

[0072] S9. Validity screening: The main control module 27 judges whether the pressure signal fluctuates abnormally, whether the displacement and temperature match, and whether the multiple temperature sensors 7 have excessive deviation.

[0073] S10. Calculate the rebound force and contraction displacement. Perform force balance calculation based on the pressure signal and the current support force output value to obtain the rebound force; perform compensation calculation based on the vertical displacement signal and the piston rod extension amount to obtain the cooling contraction displacement.

[0074] S11. Determine whether the true contraction condition is met. See the specific judgment logic below. Figure 8 If not, return to S7; if yes, proceed to S12.

[0075] S12. Calculate the support force compensation amount;

[0076] S13, hydraulic pump 19 adjusts pressure, oil cylinder 10 extends, hydraulic pump 19 increases oil circuit pressure, overflow valve 21 suppresses fluctuations, oil cylinder 10 piston rod pushes lower mold assembly 3 to squeeze material upward;

[0077] S14. Determine if the travel limit is triggered. If not, continue adjusting according to the control cycle. If yes, proceed to S15.

[0078] S15. Stop oil supply and maintain support.

[0079] S16. Cooling and shaping, the cooling components continue to operate, and the proportional temperature control valve 15 adjusts the cooling water flow rate according to the temperature sensor 7;

[0080] S17. Determine if the finalization meets the standard. If not, return to S16; if yes, proceed to S18.

[0081] S18, Mold opening and part removal: Control unit 22 controls servo electric cylinder 18 to drive upper mold assembly 2 upward, and operator removes product;

[0082] S19, pressure relief and data storage: hydraulic pump 19 relieves pressure, oil cylinder 10 piston rod retracts, data storage module 23 records the rebound force change curve, contraction displacement curve and support force control curve, and can export them through USB interface or Ethernet interface.

[0083] S20, End.

[0084] The control unit 22 sends a command to the proportional temperature control valve 15 to allow cooling water to flow into the built-in spiral water channel 14 to preheat the soft lower mold. The temperature sensor 7 monitors the lower mold temperature in real time, and when the temperature reaches the preheating target, it sends a preheating target completion signal back to the control unit 22.

[0085] The operator injects the molten rheotropic material into the material carrying tank of the lower mold assembly 3. The control unit 22 instructs the servo electric cylinder 18 to start, driving the upper mold assembly 2 to move vertically downward along the guide column. After the upper mold assembly 2 and the lower mold assembly 3 are connected, a closed mold cavity is formed, and the pressing pressure can be controlled between 0.5kN and 1kN.

[0086] Control unit 22 commands hydraulic pump 19 to start, injecting hydraulic oil into cylinder 10 through the oil circuit. Elastic support unit 4 outputs initial support force, which can be controlled between 0.2kN and 0.5kN, allowing the material to initially adhere without excessive compression. Control unit 22 controls proportional temperature control valve 15 to adjust the cooling water flow rate based on the detection value of temperature sensor 7, allowing the material to gradually solidify and shape.

[0087] Pressure sensor 5, displacement sensor 6, and temperature sensor 7 synchronously acquire data. Pressure sensor 5 outputs an analog signal, displacement sensor 6 outputs a digital signal, and temperature sensor 7 outputs a resistance signal. The signals are processed through primary link 24, secondary link 25, and tertiary link 26 before being transmitted to the main control module 27. The main control module 27 performs validity screening and determines the actual contraction.

[0088] When the temperature drop ΔT ≥ 3℃, the shrinkage displacement ΔL ≥ 0.05mm, and the rebound force drop ΔF reaches the preset rebound force threshold, the control unit 22 determines it to be a true shrinkage state and generates a control command for the hydraulic pump 19. The hydraulic pump 19 increases the oil circuit pressure, the piston rod of the cylinder 10 extends by the compensation amount, and pushes the lower mold assembly 3 upward to squeeze the material, so that the material keeps in contact with the upper mold cavity.

[0089] like Figure 8 As shown, the contraction judgment and support force compensation sub-process includes:

[0090] S20: Receives pressure, displacement, and temperature signals;

[0091] S21. Pressure decoupling: Based on the resultant force detected by pressure sensor 5 and the current support force output value Fs, force balance calculation is performed to obtain the rebound force Fr of the soft material on the material, that is, Fr = F detection - Fs component.

[0092] S22, Displacement compensation: The vertical displacement detected by displacement sensor 6 and the extension amount of piston rod of oil cylinder 10 are used for compensation calculation to obtain the cooling contraction displacement ΔL, that is, ΔL = L detection - L support compensation.

[0093] S23. Calculate the temperature drop ΔT;

[0094] S24. Determine if ΔT is ≥3℃. If not, it is determined to be interference, and return to the acquisition process.

[0095] S25. Determine if ΔL ≥ 0.05 mm. If not, determine it as interference and return to data acquisition.

[0096] S26. Determine whether ΔF reaches the preset rebound force threshold. The preset rebound force threshold is set according to the hardness of the soft material. For low-hardness silicone, it is 0.8%-1%, and for high-hardness rubber, it is 3%. If not, it is determined to be interference, and the data acquisition is returned.

[0097] S27. If all three conditions are met, it is determined to be a true contraction state.

[0098] S28. Calculate the support force compensation amount;

[0099] S29, hydraulic pump 19 pressure adjustment, oil cylinder 10 extends;

[0100] S30. Determine if the travel limit is triggered. If not, continue adjusting. If yes, proceed to S31.

[0101] S31. Stop fuel supply, record data, and return to the main process.

[0102] During the extension of the piston rod, the stroke limiter 11 moves with the piston rod. When the extension reaches the preset value, the displacement trigger switch 12 aligns with the fixed reference 13, and the control unit 22 controls the hydraulic pump 19 to stop supplying oil to prevent excessive compression.

[0103] The cooling components continue to operate until the material temperature drops to the set temperature, achieving complete solidification. Temperature sensor 7 sends a signal to control unit 22 indicating that the molding has met the standard. Control unit 22 instructs servo electric cylinder 18 to drive upper mold assembly 2 upward, causing upper mold assembly 2 to detach from lower mold assembly 3. The operator removes the molded product. Hydraulic pump 19 depressurizes, piston rod of cylinder 10 retracts to its initial position, and elastic support unit 4 returns to standby status.

[0104] The data storage module 23 automatically records the springback force change curve, shrinkage displacement curve, and support force control curve during the molding process. Operators can export the data via USB or Ethernet interface to optimize the threshold and support force compensation coefficient in the temperature-shrinkage-springback force correlation rules, thereby improving the adaptability and accuracy of subsequent production.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A compression molding machine for forming soft molds, characterized in that, include: Rack (1); The upper mold assembly (2) is vertically mounted on the upper part of the frame (1); The lower mold assembly (3) is located at the lower part of the frame (1). Its mold body is made of soft material and is used to carry rheological materials. It cooperates with the upper mold assembly (2) to form a closed mold cavity that accommodates rheological materials. The elastic support unit (4) includes a cylinder (10), a hydraulic pump (19), an oil tank (20), and an overflow valve (21). The bottom end of the cylinder body of the cylinder (10) is fixed to the frame (1). The top end of the piston rod of the cylinder (10) is fixedly connected to the bottom of the lower mold assembly (3). The hydraulic pump (19) is connected to the cylinder (10) through an oil circuit. The oil tank (20) is connected to the hydraulic pump (19) through an oil circuit. The overflow valve (21) is set on the oil circuit between the hydraulic pump (19) and the cylinder (10) to suppress oil circuit pressure fluctuations. A shrinkage sensing component is associated with the lower mold assembly (3). The shrinkage sensing component includes a pressure sensor (5), a displacement sensor (6), and a temperature sensor (7). Multiple pressure sensors (5) are provided and distributed along the connection surface between the lower mold assembly (3) and the elastic support unit (4) to detect the pressure signal transmitted from the lower mold assembly (3) to the elastic support unit (4). The fixed end of the displacement sensor (6) is installed on the frame (1), and the detection end is set corresponding to the lower mold assembly (3) to detect the vertical displacement signal of the lower mold assembly (3). The temperature sensor (7) is attached to the edge of the mold cavity of the lower mold assembly (3) to detect the temperature signal of the lower mold assembly (3). The control unit (22) is electrically connected to the pressure sensor (5), displacement sensor (6), temperature sensor (7) and hydraulic pump (19). The control unit (22) is configured to: perform force balance calculation based on the pressure signal and the current support force output value of the elastic support unit (4) to obtain the rebound force of the soft material on the material; perform compensation calculation based on the vertical displacement signal and the extension amount of the piston rod of the oil cylinder (10) to obtain the shrinkage displacement of the soft material due to cooling; when the temperature drop ΔT represented by the temperature signal is ≥3℃, the shrinkage displacement ΔL is ≥0.05mm and the decrease in rebound force ΔF reaches the preset rebound force threshold, it is determined to be a true shrinkage state. Send a control command to the hydraulic pump (19) to extend the piston rod of the cylinder (10) by a compensation amount, and push the lower mold assembly (3) to squeeze the material upward to maintain the material in contact with the mold cavity of the upper mold assembly (2); The stroke limit component (11) is fixed to the bottom of the piston rod and has a built-in displacement trigger switch (12). A fixed reference (13) is set on the inner wall of the oil cylinder (10) and cooperates with the displacement trigger switch (12); When the extension and retraction of the piston rod reaches a preset value that matches the maximum shrinkage of the soft material, the displacement trigger switch (12) is positioned relative to the fixed reference (13) to trigger a limit signal, and the control unit (22) controls the hydraulic pump (19) to stop supplying oil according to the limit signal.

2. The compression molding machine for forming soft molds according to claim 1, characterized in that: Five pressure sensors (5) are provided, which are respectively arranged at the four corners and the center of the bottom of the lower mold assembly (3). Each pressure sensor (5) is provided with a rigid conductive pad (8) on the connection surface between it and the lower mold assembly (3).

3. A compression molding machine for forming soft molds according to claim 2, characterized in that: The displacement sensor (6) is a laser displacement sensor. Its fixed end is rigidly connected to the frame (1) through a bracket, and its detection end is vertically aligned with the side of the mold base of the lower mold assembly (3). A high reflectivity target (9) is provided on the side of the mold base.

4. A compression molding machine for forming soft molds according to claim 1, characterized in that: The preset rebound force threshold is set according to the hardness of the soft material. When the soft material is low-hardness silicone, the preset rebound force threshold is 0.8%-1%. When the soft material is high-hardness rubber, the preset rebound force threshold is 3%.

5. A compression molding machine for forming soft molds according to claim 1, characterized in that: It also includes a cooling component, which is a built-in spiral water channel (14) and is respectively opened in the mold core of the upper mold component (2) and the mold base of the lower mold component (3). The water inlet of the cooling component is connected to a proportional temperature control valve (15), which is electrically connected to the control unit (22) and dynamically adjusts the cooling water flow rate according to the detection value of the shrinkage sensing component.

6. A compression molding machine for forming soft molds according to claim 1, characterized in that: It also includes a guiding mechanism, which includes a guide rail (16) fixed vertically to the frame (1) and a slider (17) fixed to the side of the lower mold assembly (3) and slidingly engaged with the guide rail (16).

7. A compression molding machine for forming soft molds according to claim 1, characterized in that: The control unit (22) includes a primary link (24), a secondary link (25), a tertiary link (26), and a main control module (27). The primary link (24) is used to receive the analog signal output by the pressure sensor (5), the digital signal output by the displacement sensor (6), and the resistance signal output by the temperature sensor (7). The secondary link (25) is used to amplify and filter analog signals, isolate and convert digital signals, and perform constant current source conversion and analog-to-digital conversion on resistance signals; The three-level link (26) is used to transmit the conditioned signal to the main control module (27).

8. A compression molding machine for forming soft molds according to claim 7, characterized in that: The main control module (27) is also configured to perform validity screening on the received signals: when the signal fluctuation amplitude of any pressure sensor (5) exceeds 5% within 100ms, the data of that pressure sensor (5) is discarded and replaced with the average value of other pressure sensors (5) at the same location; When the displacement change of the displacement sensor (6) does not match the temperature drop of the temperature sensor (7), it is determined to be a signal distortion and the backup displacement sensor (6) is activated. When the deviation of the detection values ​​of multiple temperature sensors (7) exceeds 2°C, it is determined to be a local temperature abnormality, and the pressure signal is given priority as the basis for judging the rebound force.

9. A compression molding machine for forming soft molds according to claim 1, characterized in that: The control unit (22) also integrates a data storage module (23), which is used to record the spring force change curve, shrinkage displacement curve and support force control curve during each molding process, and supports data export via USB interface or Ethernet interface.

10. A compression molding machine for forming soft molds according to claim 1, characterized in that: The upper mold assembly (2) is driven to lift by a servo electric cylinder (18), which is fixed to the top of the frame (1) and electrically connected to the control unit (22).

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