A foaming mold and a foaming method

Abstract

The application relates to the field of foaming forming technology, in particular to a foaming mold and a foaming method, a driving module, a movable frame, an upper mold and a lower mold, the movable frame is movably arranged at the top end of a fixed frame through a connecting module, the driving module is arranged between the fixed frame and the movable frame, the driving module is used for pressing the movable frame, the lower mold is fixedly arranged on the fixed frame, the upper mold is fixedly arranged on the movable frame, and the connecting module is used for avoiding the collision between the upper mold and the lower mold; one connecting module is arranged between the fixed frame and the movable frame to avoid the mutual collision mode of the upper mold and the lower mold, so that the upper mold and the lower mold can be effectively protected.

Description

Technical Field

[0001] This invention relates to the field of foam molding technology, and in particular to a foaming mold and a foaming method. Background Technology

[0002] Polyurethane foam molding is a process in which foaming raw materials are injected into a mold cavity, and the foam expands through a cross-linking reaction to obtain a foamed product of a predetermined shape. During the foaming process, the locking stability of the mold and the temperature uniformity of the cavity directly affect the cell structure, dimensional accuracy, and mechanical properties of the foamed product. The existing technical solutions have the following drawbacks: Large polyurethane foam parts are generally shaped using aluminum alloy molds. Aluminum alloy has a low density, so the molds made from it are lighter, which is more advantageous in polyurethane foaming. Existing polyurethane foam molds require a locking structure to lock the upper and lower molds during use to prevent them from being stretched open during molding and to avoid flash on the bonding surface. However, existing polyurethane foam molds do not have safety locks, which pose a risk of collision between the upper and lower molds. Collision between the upper and lower molds can cause damage to the inner wall, resulting in defects on the surface of the molded item. Therefore, a new type of automated polyurethane foam mold is needed. Summary of the Invention

[0003] The purpose of this invention is to provide a foaming mold and a foaming method to solve the problems existing in the prior art.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A foaming mold includes a fixed frame, a drive module, a movable frame, an upper mold, and a lower mold. The movable frame is movably mounted on the top of the fixed frame via a connecting module. The drive module is disposed between the fixed frame and the movable frame and is used to press the movable frame. The lower mold is fixedly mounted on the fixed frame, and the upper mold is fixedly mounted on the movable frame. The connecting module is used to prevent the upper and lower molds from colliding.

[0005] By adopting the above technical solution, a connecting module is set between the fixed frame and the movable frame to avoid collision between the upper and lower molds, which can effectively protect the upper and lower molds.

[0006] In a further embodiment, the connecting assembly includes a support plate, a mounting plate, a rotating rod, a connecting arm, and an adjusting knob. The support plate is symmetrically fixedly mounted on the fixed frame, and the mounting plate is symmetrically fixedly mounted on the support plate. The mounting plate has mounting holes and oblong holes. The length direction of the mounting holes is vertical. The oblong holes communicate with the middle section of the mounting holes, and the center of the oblong holes is located at the top of the mounting holes. A straight hole is opened on one side of the mounting plate that is opposite to each other. The straight hole is located at the bottom of the mounting holes. A rotating rod passes through the straight hole. One end of the rotating rod passes through the lower mold and extends to the outside. An adjusting knob is fixedly mounted on one end of the rotating rod. One end of the rotating rod is fixedly mounted on one end of a first connecting rod. The other end of the first connecting rod is rotatably connected to one end of a second connecting rod. A first round rod passes through the mounting hole, and a second round rod passes through the oblong hole. The first round rod and the second round rod are fixedly mounted on the same connecting arm. The connecting arm is located between the mounting plates. The other end of the second connecting rod is rotatably mounted to the middle section of the connecting arm. The connecting arm is fixedly mounted to the movable frame through a fixing rod.

[0007] By adopting the above technical solution, rotating the adjustment knob can drive the rotating rod to rotate synchronously. The rotating rod drives the first connecting rod to make a circular rotation, and then pushes and pulls the connecting arm through the transmission of the second connecting rod. At this time, the first round rod on the connecting arm makes a vertical linear movement along the vertical mounting hole of the mounting plate, so that the second round rod moves up and down in the mounting hole first. The distance between the axes of the first round rod and the second round rod is the same as the distance between the top of the mounting hole and the connection point between the waist-shaped hole and the mounting hole. When the first round rod moves to the top of the mounting hole, the second round rod swings along the arc-shaped waist-shaped hole, so that the connecting arm drives the upper mold to complete the vertical lifting and lowering first, and then flipping and opening and closing, realizing the smooth opening and closing of the upper mold and the lower mold, thereby avoiding direct hard collision between the upper and lower molds, effectively protecting the inner wall of the mold cavity from bump damage. Moreover, when the first connecting rod and the second connecting rod are collinear, and the second round rod also moves from the arc-shaped hole to the mounting hole and is in the dead point position, the upper mold is firmly locked on the lower mold, which can withstand the internal expansion force generated during the polyurethane foaming process and prevent the mold from being stretched open.

[0008] In a further embodiment, the drive module further includes a hydraulic cylinder, one end of which is movably connected to a fixed frame, and the other end of which is movably connected to a square frame. A rotating shaft is fixedly installed in the middle area of ​​the square frame, and multiple bearing seats fixedly installed on the top of the fixed frame are sleeved on the rotating shaft. Multiple adjustable pressure rods are provided at the bottom of the square frame.

[0009] By adopting the above technical solution, the hydraulic cylinder extends and retracts to drive the square frame to rotate around the pivot within the bearing seat. This causes multiple pressure rods at the bottom of the square frame to press down synchronously with the swing of the square frame and press against the upper surface of the movable frame. This applies a uniformly distributed auxiliary locking force to the upper mold. The auxiliary locking force and the dead-point locking of the connecting module work together to form a double locking guarantee, preventing the mold from being stretched open due to excessive internal expansion force during the polyurethane foam molding process. This ensures that the bonding surfaces always remain tightly fitted and do not produce flash.

[0010] In a further embodiment, the pressure rod includes a sleeve and a bearing rod. The bearing rod passes through the sleeve, and a sliding groove is formed on the inner wall of the sleeve. The inner wall of the sleeve is provided with mounting grooves at intervals from top to bottom, and the mounting grooves communicate with the sliding grooves. A slider is provided on the outer wall of the bearing rod, and the slider is slidably installed in the mounting groove. The length direction of the sliding groove is vertical, and the length direction of the mounting groove is horizontal. A receiving groove is provided at the bottom of the pressure rod, and a pressure sensor is provided in the receiving groove.

[0011] By adopting the above technical solution, when it is necessary to adjust the length of the pressure bar to adapt to different mold thicknesses, the bearing bar is slid up and down along the groove inside the sleeve to the target position and then rotated horizontally so that the slider is locked into the corresponding mounting groove, thus completing the length locking. Furthermore, the pressure sensor at the bottom of the pressure bar provides real-time feedback on the clamping force when the movable frame is clamped. Based on this, the operator can accurately adjust the locking force of each pressure bar to the preset range, ensuring that the locking force is sufficient to resist the foaming expansion force and avoiding mold deformation or damage to the movable frame due to excessive clamping.

[0012] In a further embodiment, the lower mold includes an inner mold and an outer mold. The outer wall of the inner mold and the interior of the outer mold form a hollow cavity. A temperature control module is provided in the hollow cavity. The temperature control module includes a heat exchange tube, a feed tube, and a discharge tube. The hollow cavity has the same shape as the heat exchange tube. The feed tube is connected to one end of the heat exchange tube, and the discharge tube is connected to the other end of the heat exchange tube. Both the feed tube and the discharge tube are fixedly installed on the lower mold.

[0013] By adopting the above technical solution, during the polyurethane foaming process, a constant-temperature medium is added to the heat exchange tubes laid in the hollow cavity through the feed pipe according to the process requirements. After flowing through the heat exchange tubes, the constant-temperature medium is discharged from the discharge pipe. Since the hollow cavity and the heat exchange tubes are the same shape, the heat exchange tubes fit tightly with the inner and outer molds, allowing the heat from the heat exchange tubes to be directly transferred to the inner and outer molds. This prevents secondary heat transfer through the air during the transfer process, which would reduce efficiency. This allows for uniform temperature control of the lower mold cavity, keeping the mold temperature within the optimal range required for the foaming reaction. It avoids uneven foaming caused by excessively high or low mold temperatures, thereby improving the consistency and yield of the molded parts and reducing surface defects caused by temperature fluctuations.

[0014] This invention also discloses a foaming method for a foaming mold, comprising the following steps: Step S1: Mold closing and locking. After injecting the polyurethane raw material to be foamed into the lower mold cavity, the moving frame is driven down by the drive module to complete the mold closing between the upper and lower molds. The upper mold is locked onto the lower mold by rotating the adjustment knob through the connection module. Step S2: Foaming and molding. Adjust the length of the pressure bar to press it against the movable frame and confirm that the locking force meets the standard through the pressure sensor. At the same time, use the temperature control module to adjust the temperature of the lower mold to the temperature range required by the foaming process and keep it stable until the foaming and molding is completed. Step S3: Open the mold and remove the part. First, loosen the pressure rod and release the auxiliary locking. Then, turn the adjustment knob in the opposite direction to make the upper mold rise vertically through the connecting module to demold and then flip open to remove the formed part.

[0015] By adopting the above technical solution, the composite guide rail structure formed by the combination of mounting holes and arc-shaped waist-shaped holes in the connecting module strictly constrains the movement trajectory of the upper mold to a two-stage path of vertical descent followed by flipping and closing. During the vertical descent stage, the upper and lower mold cavities are ensured to be completely aligned horizontally before flipping and closing, thus preventing the possibility of hard collisions at the edges of the upper and lower mold cavities when traditional molds directly flip or close at an angle. This effectively protects the integrity and surface finish of the aluminum alloy mold's inner wall, avoiding quality problems caused by surface defects in the formed parts due to damage to the mold's inner wall. Simultaneously, when the hinge point of the first connecting rod and the second connecting rod... When the fixed point of the first connecting rod and the rotating rod, and the rotating point of the second connecting rod and the connecting arm are collinear, any reverse thrust from the direction of the upper mold will be transmitted along the connecting rod axis to the rotation center of the rotating rod. The lever arm is zero, and no torque can be generated to rotate the rotating rod, thus achieving mechanical self-locking. This provides the first reliable guarantee for withstanding the internal expansion force of polyurethane during the subsequent foaming process. Combined with the uniform auxiliary locking force applied by the pressure rod, a double locking structure is formed, which can completely resist the internal expansion force during the foaming process and prevent gaps and flash from appearing on the mold surface. Stable mold temperature control throughout the process ensures that the polyurethane foaming reaction proceeds uniformly, improving the density consistency and surface quality of the finished product.

[0016] In a further embodiment, step S1 further includes: Pre-treatment before mold closing: Before mold closing, the temperature control module is activated to preheat the lower mold so that the surface temperature of the inner mold of the lower mold reaches the initial reaction temperature of the polyurethane raw material. Before injection, release agent is evenly sprayed onto the inner wall of the mold cavity of the upper and lower molds, and residual foaming material and impurities on the mold closing and bonding surface are wiped clean.

[0017] By adopting the above technical solutions, preheating can avoid the problem of local reaction lag after the cold mold comes into contact with the high temperature foaming material, ensure uniform mold temperature in the initial stage of foaming, and prevent defects such as insufficient or over-foaming in some areas; the release agent can reduce the risk of sticking when the finished product is demolded, reduce surface tearing damage, and improve the appearance qualification rate of the finished product; cleaning the mold closing surface can prevent residual material from being stuck between the mold closing surfaces, which would cause the mold to not close tightly, prevent overflow and flash during subsequent foaming, and ensure the sealing and locking accuracy of the mold closing.

[0018] In a further embodiment, step S2 further includes: Step S21: Locking force grade calibration. Calculate the minimum locking force required based on the grade of the polyurethane raw material to be foamed, the foaming ratio and the projected area of ​​the mold cavity. Set the target range of locking force based on this. After the value fed back by the pressure sensor at the bottom of the pressure rod falls into the target range, rotate the bearing rod to make the slider lock into the corresponding mounting groove to complete the length locking. Step S22: Closed-loop control of mold temperature. Temperature acquisition points are set up at multiple points such as the corners and center of the cavity of the lower mold inner mold. The difference between the acquired temperature and the set temperature is compared in real time based on the set temperature required by the foaming process. The flow rate and temperature of the constant temperature medium in the heat exchange tube are dynamically adjusted according to the difference.

[0019] By adopting the above technical solutions, graded calibration ensures that the locking force applied by each pressure bar matches the process requirements, avoiding insufficient pressure in some areas leading to local overflow, or excessive pressure causing mold deformation. The closed-loop temperature control method, which combines multi-point data acquisition with dynamic regulation, can accurately correct temperature deviations in different locations of the cavity, solving the problems of rapid heat dissipation at the corners and high temperature accumulation at the center due to heat release. This ensures that the temperature in all areas of the entire mold cavity is stably maintained within the process requirements, further improving the quality of foam molding.

[0020] In summary, the present invention has the following beneficial effects: 1. By rotating the adjustment knob, the rotating rod can be driven to rotate synchronously. The rotating rod drives the first connecting rod to make a circular rotation, and then pushes and pulls the connecting arm through the transmission of the second connecting rod. At this time, the first round rod on the connecting arm makes a vertical linear movement along the vertical mounting hole of the mounting plate, so that the second round rod moves up and down in the mounting hole first. The distance between the axes of the first round rod and the second round rod is the same as the distance between the top of the mounting hole and the connection point between the waist-shaped hole and the mounting hole. When the first round rod moves to the top of the mounting hole, the second round rod swings along the arc-shaped waist-shaped hole, so that the connecting arm drives the upper mold to complete the vertical lifting and lowering first, and then flipping and opening and closing, realizing the effect of smooth opening and closing of the upper and lower molds. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the drive module of the present invention; Figure 3 This is a schematic diagram of the temperature control module of the present invention; Figure 4 This is a schematic diagram of the structure of the connection component of the present invention; Figure 5 This is a schematic diagram of the sleeve structure of the present invention; Figure 6 This is a flowchart of embodiment 2.

[0022] In the diagram, 1. Fixed frame; 2. Drive module; 21. Hydraulic cylinder; 3. Movable frame; 4. Upper mold; 5. Lower mold; 6. Connecting assembly; 61. Support plate; 62. Mounting plate; 63. Rotating rod; 64. Connecting arm; 65. Adjusting knob; 7. First round rod; 8. Second round rod; 9. Square frame; 10. Rotating shaft; 11. Pressure rod; 111. Sleeve; 112. Bearing rod; 12. Slider; 13. Temperature control module. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings.

[0024] It should be noted that in the description of this invention, any descriptions of orientation, such as up, down, front, back, left, right, etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of this invention.

[0025] Example 1: like Figures 1-5 As shown, a foaming mold includes a fixed frame 1, a drive module 2, a movable frame 3, an upper mold 4, and a lower mold 5. The movable frame 3 is movably mounted on the top of the fixed frame 1 via a connecting module. The drive module 2 is disposed between the fixed frame 1 and the movable frame 3 and is used to press the movable frame 3. The lower mold 5 is fixedly mounted on the fixed frame 1, and the upper mold 4 is fixedly mounted on the movable frame 3. The connecting module is used to prevent the upper and lower molds 5 from colliding. By setting a connecting module between the fixed frame 1 and the movable frame 3 to prevent the upper and lower molds 5 from colliding with each other, the upper and lower molds 5 can be effectively protected.

[0026] The connecting assembly 6 includes a support plate 61, a mounting plate 62, a rotating rod 63, a connecting arm 64, and an adjusting knob 65. The support plate 61 is fixedly mounted on the fixing frame 1. The mounting plate 62 is symmetrically fixedly mounted on the support plate 61. The mounting plate 62 has mounting holes and oblong holes. The length direction of the mounting holes is vertical. The oblong holes are connected to the middle section of the mounting holes, and the center of the oblong holes is located at the top of the mounting holes. A straight hole is opened on one side of the mounting plate 62 that is opposite to the mounting holes. The straight hole is located at the bottom of the mounting holes. The rotating rod 63 passes through the straight hole. One end of the rotating rod 63... Extending outward through the lower mold 5, one end of the rotating rod 63 is fixedly equipped with an adjustment knob 65, and the other end of the rotating rod 63 is fixedly equipped with one end of the first connecting rod. The other end of the first connecting rod is rotatably connected to one end of the second connecting rod. A first round rod 7 passes through the mounting hole, and a second round rod 8 passes through the oblong hole. The first round rod 7 and the second round rod 8 are fixedly equipped with the same connecting arm 64. The connecting arm 64 is located between the mounting plates. The other end of the second connecting rod is rotatably installed with the middle section of the connecting arm 64. The connecting arm 64 is fixedly installed with the movable frame 3 through a fixing rod.

[0027] Rotating the adjustment knob 65 will drive the rotating rod 63 to rotate synchronously. The rotating rod 63 drives the first connecting rod to perform a circular rotation, which in turn drives the connecting arm 64 through the transmission of the second connecting rod. At this time, the first round rod 7 on the connecting arm 64 moves up and down along the vertical mounting hole of the mounting plate 62, thereby causing the second round rod 8 to move up and down in the mounting hole first. The distance between the axes of the first round rod 7 and the second round rod 8 is the same as the distance between the top of the mounting hole and the connection point between the oblong hole and the mounting hole, so that when the first round rod 7 moves to the top of the mounting hole... When the second round rod 8 swings along the arc-shaped waist hole, the connecting arm 64 drives the upper mold 4 to first rise and fall vertically, and then flip open and close, so as to realize the smooth opening and closing of the upper mold 4 and the lower mold 5, thereby avoiding direct hard collision between the upper and lower molds 5, and effectively protecting the inner wall of the mold cavity from bump damage. When the first connecting rod and the second connecting rod are collinear, and the second round rod 8 also moves from the arc-shaped hole to the mounting hole and is in the dead point position, the upper mold 4 is firmly locked on the lower mold 5, which can withstand the internal expansion force generated during the polyurethane foaming process and prevent the mold from being stretched open.

[0028] The drive module 2 also includes a hydraulic cylinder 21. One end of the hydraulic cylinder 21 is movably connected to the fixed frame 1, and the other end of the hydraulic cylinder 21 is movably connected to the square frame 9. A rotating shaft 10 is fixedly installed in the middle area of ​​the square frame 9. Multiple bearing seats fixedly installed on the top of the fixed frame 1 are sleeved on the rotating shaft 10. Multiple adjustable pressure rods 11 are provided at the bottom of the square frame 9. The hydraulic cylinder 21 extends and retracts to drive the square frame 9 to rotate around the rotating shaft 10 in the bearing seats, so that the multiple pressure rods 11 at the bottom of the square frame 9 press down synchronously with the swing of the square frame 9 and press against the upper surface of the movable frame 3, thereby applying a uniformly distributed auxiliary locking force to the upper mold 4. The auxiliary locking force and the dead point locking of the connecting module cooperate to form a double locking guarantee, preventing the mold from being stretched open due to excessive internal expansion force during the polyurethane foam molding process, and ensuring that the bonding surface always remains tightly fitted and does not produce flash.

[0029] The pressure rod 11 includes a sleeve 111 and a bearing rod 112. The bearing rod 112 passes through the sleeve 111. A sliding groove is formed on the inner wall of the sleeve 111. Installation grooves are spaced apart from top to bottom on the inner wall of the sleeve 111, and the installation grooves communicate with the sliding grooves. A slider 12 is provided on the outer wall of the bearing rod 112. The slider 12 is slidably installed in the installation groove. The length direction of the sliding groove is vertical, and the length direction of the installation groove is horizontal. A receiving groove is provided at the bottom of the pressure rod 11, and a pressure sensor is installed in the receiving groove. When it is necessary to adjust the length of the pressure rod 11... To accommodate different mold thicknesses or adjust the clamping degree, the bearing rod 112 is slid up and down along the groove inside the sleeve 111 to the target position and then rotated horizontally so that the slider 12 is engaged in the corresponding mounting groove, thus completing the length locking. Furthermore, the pressure sensor at the bottom of the pressure rod 11 provides real-time feedback on the clamping force when clamping the movable frame 3. Based on this, the operator can precisely adjust the locking force of each pressure rod 11 to the preset range, ensuring that the locking force is sufficient to resist the foaming expansion force and avoiding mold deformation or damage to the movable frame 3 due to excessive clamping.

[0030] The lower mold 5 includes an inner mold and an outer mold. The outer wall of the inner mold and the interior of the outer mold form a hollow cavity. A temperature control module 13 is installed in the hollow cavity. The temperature control module 13 includes a heat exchange tube, a feed pipe, and a discharge pipe. The hollow cavity and the heat exchange tube have the same shape. The feed pipe is connected to one end of the heat exchange tube, and the discharge pipe is connected to the other end of the heat exchange tube. Both the feed pipe and the discharge pipe are fixedly installed on the lower mold 5. During the polyurethane foaming process, a constant temperature medium is added to the heat exchange tube laid in the hollow cavity through the feed pipe according to the process requirements. After flowing through the heat exchange tube, the constant temperature medium is discharged from the discharge pipe. Furthermore, the hollow cavity is identical in shape to the heat exchange tube, ensuring a tight fit between the heat exchange tube and the inner and outer molds. This allows the heat from the heat exchange tube to be directly transferred to the inner and outer molds, preventing secondary heat transfer through the air and thus avoiding efficiency reduction. This enables uniform temperature control of the lower mold cavity, maintaining the mold temperature within the optimal range required for the foaming reaction. It avoids uneven foaming caused by excessively high or low mold temperatures, thereby improving the consistency and yield of the molded parts and reducing surface defects caused by temperature fluctuations.

[0031] Example 2: like Figure 6 As shown, a foaming method for a foaming mold includes the following steps: Step S1: Mold Closure and Locking. Before foaming production begins, pre-treatment before mold closure is performed: Temperature control module 13 is activated, and a constant-temperature medium is introduced into the heat exchanger tube inside the hollow cavity of the lower mold 5 through the feed pipe. The constant-temperature medium circulates within the heat exchanger tube and is then discharged through the discharge pipe, preheating the inner mold. This ensures that the surface temperature of the lower mold 5 uniformly reaches the initial reaction temperature of the polyurethane raw material, typically 40-60 degrees Celsius. During preheating, thermocouples positioned at key locations within the mold cavity are used to monitor the temperature rise in real time. Preheating is considered complete once the readings at each measuring point have entered the target range and stabilized. The purpose is to avoid localized temperature drops when the cold mold comes into contact with the high-temperature foaming material, which could lead to delayed reaction or over-foaming. After preheating to the required standard, a release agent is evenly sprayed onto the inner walls of the upper and lower mold cavities, focusing on covering easily sticking areas such as chamfers, grooves, and deep cavities. Then, the mating surfaces of the upper and lower molds 5 are carefully wiped clean with a non-woven cloth to remove residual foaming material debris, cured particles, and excess release agent from the previous cycle, ensuring a clean and flat mating surface. Residual impurities on the mating surface will directly affect the mold sealing, causing overflow and flash during foaming and increasing the risk of mold damage. After pretreatment, the polyurethane raw material to be foamed, measured according to the process ratio, is injected into the lower mold cavity along a set trajectory. During injection, the pouring speed is controlled to be uniform and the drop point distribution is reasonable, allowing the raw material to initially spread evenly within the mold cavity. After the material is injected, drive module 2 is immediately activated: the piston rod of hydraulic cylinder 21 extends and drives the square frame 9 to rotate around the shaft 10 within the bearing seat. The pressure rod 11 at the bottom of the square frame 9 swings down with the square frame 9, pushing the movable frame 3 and the upper mold 4 downward. As the upper mold 4 approaches the lower mold 5, the composite motion track formed by the mounting holes and the arc-shaped waist-shaped holes inside the connecting module precisely constrains the movement trajectory of the upper mold 4, so that the upper mold 4 first moves downward vertically, and the edges of the cavity openings of the upper and lower molds 5 always remain parallel and aligned. This avoids the hard collision of the edges of the upper and lower molds 5 openings due to the intersection of movement trajectories when the mold is directly flipped and closed in traditional molds, fundamentally protecting the integrity of the inner wall of the aluminum alloy mold. After descending vertically to the position where the cavity openings are about to contact, the upper mold 4 continues to flip and close under the guidance of the connecting module, smoothly locking onto the lower mold 5. After the mold is closed, the operator rotates the adjustment knob 65 to drive the connecting module to the dead-point self-locking position, and the upper mold 4 is firmly locked onto the lower mold 5, forming the first mechanical locking guarantee.

[0032] Step S2: Foaming and molding.

[0033] After the mold is closed and locked, the locking force is first calibrated. Based on the grade of the polyurethane raw material in this batch, the maximum internal foaming pressure of the raw material under the process conditions is obtained from the supplier's technical data sheet. The unit is megapascals (MPa). If no readily available data is available, pressure sensors are pre-embedded in the mold cavity during the trial molding stage for actual measurement and calibration. Then, the projected area A of the mold cavity on the mold mating surface is determined according to the mold drawings, in square millimeters. The maximum foaming bulging force is calculated using the following formula. The unit is kilonewtons. Multiply this by a safety factor. The minimum auxiliary locking force is determined. : Among them, the safety factor The value is taken as 1.5 to 2.5, considering factors such as the fluctuation range of foaming pressure between raw material batches, pressure drift caused by mold temperature changes, and the aging allowance of the mold closing surface seal. , *1.3 represents the upper limit, defining the target range for the locking force. The length of the pressure rod 11 is pre-adjusted before mold closing based on the estimated distance from the upper surface of the movable frame 3 to the working angle of the square frame 9 after mold closure, relative to the mounting reference surface of the pressure rod 11. Each bearing rod 112 is slid up and down along the inner wall groove of the sleeve 111 to its approximate position, then rotated horizontally to lock the slider 12 into the corresponding mounting slot. This length remains unchanged throughout the foaming cycle. After mold closing, the hydraulic cylinder 21 continues to apply force to drive the square frame 9 to rotate. The bottom of each pressure rod 11 simultaneously contacts the upper surface of the movable frame 3. The operator observes the real-time locking force value fed back by the pressure sensor in the accommodating groove at the bottom of each pressure rod 11. By adjusting the oil supply pressure of the hydraulic system, the thrust of the hydraulic cylinder 21 is changed. Increased oil supply pressure increases the locking force of the pressure rod 11 on the movable frame 3, while decreased oil supply pressure decreases the locking force. This process is repeated until the feedback values ​​of all pressure rods 11 stably fall within the target range. If the feedback value of a certain pressure bar 11 consistently deviates from the target range and cannot be adjusted back to the target range by adjusting the system oil pressure, it is necessary to check whether the pre-adjusted length of that pressure bar 11 differs significantly from other pressure bars 11 and readjust it. After all locking forces meet the target, the hydraulic system maintains a stable oil supply pressure through a check valve or hydraulic lock to ensure that the auxiliary locking force does not decrease throughout the entire foaming and curing cycle. Multiple pressure bars 11 form a uniformly distributed auxiliary locking force on the upper surface of the movable frame 3, which, together with the dead-point self-locking of the connecting module, constitutes a double locking guarantee, comprehensively resisting the internal expansion force during the foaming process, ensuring that the mold-fitting surfaces always remain tightly fitted and do not produce overflow or flash.

[0034] While calibrating the locking force, the temperature control module 13 is activated to regulate the temperature of the lower mold 5. The lower mold 5 includes an inner mold and an outer mold. The outer wall of the inner mold and the interior of the outer mold form a hollow cavity. A heat exchange tube is installed in the hollow cavity, and the heat exchange tube is tightly fitted with the inner and outer molds. During temperature control, the constant temperature medium enters the heat exchange tube through the feed pipe, circulates within the heat exchange tube, and directly transfers heat to the inner and outer molds before being discharged through the discharge pipe. By adjusting the temperature and flow rate of the constant temperature medium, the temperature of the lower mold cavity 5 is maintained within the temperature range required by the foaming process, typically 45 to 65 degrees Celsius. The specific setting value is determined according to the raw material grade and process documents. Temperature regulation is maintained throughout the entire foaming and curing cycle, avoiding defects such as uneven foaming, surface bubbles, or collapse caused by excessively high or low mold temperatures, until the polyurethane raw material is fully foamed and cured.

[0035] Step S3: Open the mold and remove the parts.

[0036] After foaming and curing, the hydraulic system is first depressurized. Then, the bearing rods 112 of each pressure rod 11 are rotated in the opposite direction to disengage the slider 12 from the mounting groove. The bearing rods 112 are then retracted upwards along the groove to disengage the bottom of the pressure rod 11 from the movable frame 3. Subsequently, the hydraulic cylinder 21 drives the square frame 9 to reset in the opposite direction, so that the pressure rod 11 completely leaves the space above the movable frame 3. After the auxiliary locking is released, the operator rotates the adjustment knob 65 in the opposite direction to disengage the connecting module from the dead-point self-locking state and continues to rotate in the opposite direction. At this time, the connecting module drives the upper mold 4 to lift it vertically upwards for a certain distance, so that the upper surface and side wall of the formed part are smoothly separated from the mold cavity of the upper mold 4 to complete the demolding action. The vertical demolding method ensures that the part and the side wall of the mold cavity are separated in parallel rather than at an angle, effectively protecting the integrity of the product surface and the smoothness of the inner wall of the mold. This is also the key to solving the problem of collision damage caused by the flipping demolding of traditional molds. Subsequently, the upper mold 4 is flipped outwards and opened to the part removal angle under the guidance of the connecting module. After the upper mold 4 is fully opened, the formed part is removed from the lower mold 5 cavity. After cleaning and inspecting the cavity, the next production cycle can be prepared.

[0037] Example 3: A foaming method for a foaming mold, which differs from Example 2 in that the temperature control in step S2 adopts a closed-loop mold temperature regulation method, and step S2 is foaming molding.

[0038] After the mold is closed and locked, the locking force is first calibrated according to the method described in Example 2. ;and The target range for locking force is calculated, and the hydraulic system's oil supply pressure is adjusted to ensure that the feedback values ​​of each pressure rod 11 fall within the target range, thus completing the auxiliary locking. Simultaneously, closed-loop mold temperature control is initiated while calibrating the locking force. For temperature acquisition, multiple temperature measurement points are arranged along the cavity contour three to five millimeters below the cavity surface of the lower mold 5: at least one point is set at each corner and edge of the cavity, one point is set at the geometric center, one point is added for large planar areas at a grid of 200 mm x 200 mm, one point is set on each side of areas where wall thickness changes abruptly, and one point is set near the injection port and vent. K-type armored thermocouples with an accuracy of ±0.3℃ are used as sensors. The signal is converted into a 4-20 mA standard signal by a temperature transmitter and then input to the PLC analog input module. The heat exchange tubes within the hollow cavity of the lower mold 5 are divided into several independent control zones according to the spatial distribution of the aforementioned temperature measurement points. Within each zone, the heat exchange tubes are coiled in a serpentine pattern around the outer wall of the inner mold in the corresponding cavity area, and are brazed to achieve full contact and fit, eliminating air gap thermal resistance. Each zone's inlet is equipped with an electric regulating valve, which employs equal percentage flow characteristics, a response time of no more than three seconds, and a valve position feedback signal of four to twenty milliamps. The outlets of each zone are collected and discharged uniformly through a collection pipe. The heat exchange medium is centrally supplied by a constant temperature unit, and the main pipeline pressure is maintained stable through a variable frequency circulating pump. At the control level, the PLC establishes a mapping relationship between each temperature measurement point and the heat exchange zone. Each zone is determined by the temperature of several temperature measurement points within that area that corresponds to the set temperature. The variable with the largest deviation is taken as the controlled variable, and the controller employs a cascaded, split-range composite PID algorithm. The main loop, i.e., the temperature loop, uses the actual temperature of the temperature measurement point in that zone. With set temperature deviation As input: The output control quantity is calculated by PID control. The range is 0-100%; the secondary circuit, i.e., the valve position ring, will... As a setpoint, it is compared with the actual valve position feedback signal and then driven by a fast PI controller to actuate the electric regulating valve, ensuring accurate valve opening. The split-range control logic specifies that when... When the temperature exceeds 50%, the system determines that the area needs to be heated, and the opening degree of the electric regulating valve is adjusted accordingly. Proportional From 50% to 100% corresponds to a valve opening from 0% to 100%, during which the heating medium supplied by the constant temperature unit is introduced into this zone; when When the temperature drops below 50%, the system determines that the area needs cooling and switches the zone inlet to the cooling medium pipeline via a three-way switching valve. The cooling medium is supplied by another circuit of the constant temperature unit and has a temperature lower than [the specified value]. For the same medium at approximately 20 to 30 degrees Celsius, the opening degree of the electric regulating valve is... Inversely proportional, The valve opening ranges from 0% to 100%, corresponding to a range of 50% to 0%, thus enabling seamless switching between heating and cooling and preventing temperature runaway caused by intense exothermic foaming reaction in a single heating mode. Since the lower mold 5 is an integral metal structure, there is thermal coupling, i.e., cross-interference, between adjacent heat exchange zones through heat conduction via the mold body. To address this, three measures are taken: First, a partition groove with a depth of 3 to 5 mm and a width of 2 to 3 mm is machined on the outer wall of the inner mold at the boundary of each zone, and the groove is filled with aerogel insulation strips with a thermal conductivity of less than 0.1 W / m·K to increase the thermal resistance between adjacent zones from a physical perspective. Second, the flow direction of the medium in the heat exchange tubes of adjacent zones is designed to be opposite, so that the temperature gradient directions at the interface of the two zones are opposite and some thermal effects cancel each other out. Third, during the trial molding stage, a unit step flow increment is applied to each zone sequentially, and the temperature response of all temperature measurement points in other zones is recorded. This establishes a static gain coupling matrix between each zone. In actual operation, the PLC performs feedforward compensation on the PID output of each zone according to the coupling matrix. When the valve opening of a certain zone changes, a reverse compensation amount is synchronously added to the control output of the adjacent zone affected by it to cancel the cross-interference.

[0039] PID parameter tuning should be completed during the commissioning phase before formal production using the following steps: Place the controller in manual mode and disable integral and derivative actions. , With initial proportional gain Output a step opening signal with an amplitude of approximately 20% of full scale to the electric regulating valve. The temperature response curve of the temperature measurement point in this zone is recorded using a PLC trend chart. Three key parameters are read from the curve: pure time delay. The time constant is the time interval from the application of a step jump to the point where a detectable change in temperature begins. That is, the time required for the temperature to change from the initial stage to reach 63.2% of the final steady-state value, the process static gain. That is, the total temperature change divided by the change in valve opening. The second step is to calculate the initial parameters using the Cohen-Coon formula: ;in and The unit is minutes; considering that the temperature process is a slow process and excessive gain can easily cause oscillations, the calculated value will be changed before actual use. Multiply by a conservative factor of 0.5. Third step, establish a stable closed loop: Write the above conservative parameters into the PLC, switch the controller to automatic mode, and observe the response curve of the temperature rising from the initial value to the set temperature. At this stage, only focus on whether the system can stabilize near the set temperature without diverging; strict requirements are not placed on overshoot and settling time. Fourth step, progressively optimize the proportional gain: After the system is running stably, gradually increase the proportional gain in increments not exceeding 20% ​​of the current value. After each adjustment, observe at least three complete temperature fluctuation cycles through the PLC trend panel. For the temperature control circuit of the foaming mold, one fluctuation cycle is usually five to fifteen minutes. Record the overshoot of the temperature curve after each adjustment. This refers to the magnitude of the maximum temperature exceeding the set temperature and the attenuation ratio, which is the ratio of the amplitude of the first peak to the amplitude of the second peak. If the overshoot gradually increases and the attenuation ratio approaches 1:1, resulting in continuous constant-amplitude oscillations, it indicates that the critical gain has been reached. Record this moment Value and oscillation period The value is then used to determine the proportional gain for actual application, as shown in the following formula: Pure PI control: PID control: If it gradually increases If the temperature remains stable throughout the process and the overshoot does not exceed ±3℃, then the set that minimizes the steady-state error is selected. As the final value. Fifth step, introduce the integration effect: [The value determined in the previous step is...] Multiply by 0.7 as a conservative proportional gain when introducing the integral to leave a stability margin, and then gradually decrease the integration time from large to small. ,initial Set the time to 500 seconds, gradually shortening it in increments of 50-100 seconds. After each adjustment, observe the temperature curve for at least three fluctuation cycles, paying attention to whether the steady-state error gradually decreases and eventually disappears (i.e., whether the average temperature gets closer and closer to the set value), and whether the system exhibits low-frequency oscillations caused by integral saturation (i.e., the temperature slowly fluctuates around the set value with gradually increasing amplitude). If low-frequency oscillations occur, [further action is needed]. The price retraces to the previous non-oscillating value and locks it. If the steady-state error has been eliminated and there is no oscillation, the price continues to shorten. The temperature curve is maintained until it recovers to the set value as quickly as possible after a brief temperature fluctuation caused by material injection, and the overshoot during the recovery process does not exceed ±2℃. The sixth step is to decide whether to introduce differential action: for temperature control of foaming molds, which involves high thermal inertia... In the process, the differential action can effectively suppress overshoot and accelerate the response, as determined in the fifth step. and Based on As an initial value, observe the response curve when the temperature setpoint undergoes a step change. If the overshoot is significantly reduced compared to the case without derivative and the system exhibits no high-frequency jitter, then retain that value. If the temperature signal exhibits high-frequency noise amplification, i.e., the curve shows sawtooth fluctuations, then the output should be appropriately reduced. Or set it directly to zero. Step 7, Multi-zone Joint Debugging and Verification: After the PID parameters of each zone are tuned one by one, put all zones into automatic mode simultaneously. Perform a complete simulated foaming cycle according to the actual production process, injecting a substitute medium with the same heat capacity as the polyurethane raw material. Export the temperature curves of each temperature measuring point throughout the entire cycle using the PLC's historical data recording function, and analyze the highest temperature, lowest temperature, and maximum deviation from the set value for each point. If the temperature deviation of a certain zone exceeds ±2℃, and the deviation can be relaxed to ±3℃ in extreme heat dissipation areas at the edges, then the PID parameters of that zone should be fine-tuned. If the temperature curve shows multiple oscillations before stabilization or does not converge at all, it indicates... Too large or Too short, prioritize After reducing the value by 10% to 15%, observe the effect. If the oscillation still does not converge, then... An increase of 20%–30%; a very slow temperature rise rate, failure to follow the set value, or an excessively long recovery time after being disturbed indicates that… Too small or If it is too long, prioritize After increasing the value by 10%, observe the effect. If the response is still slow, shorten the Ti value by 20%. After each parameter adjustment, a complete simulated foaming cycle needs to be run again to verify the effect. Repeat the above steps three to five times until the temperature deviation of all temperature measuring points is controlled within ±2℃ throughout the entire curing cycle and the temperature curves at each point are consistent. This indicates that the debugging is qualified. Furthermore, during production, the PLC continuously records the temperature data of each temperature measuring point and generates historical curves. If the temperature deviation of a certain zone shows an increasing trend over several consecutive production cycles, the system will automatically issue a warning, and the operator needs to check whether there is a problem with the heat exchange pipeline in that zone.

[0040] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0041] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A foaming mold and a foaming method, characterized in that: It includes a fixed frame (1), a drive module (2), a movable frame (3), an upper mold (4), and a lower mold (5). The movable frame (3) is movably installed on the top of the fixed frame (1) through a connecting module. The drive module (2) is located between the fixed frame (1) and the movable frame (3). The drive module (2) is used to press the movable frame (3). The lower mold (5) is fixedly installed on the fixed frame (1). The upper mold (4) is fixedly installed on the movable frame (3). The connecting module is used to prevent the upper and lower molds (5) from colliding.

2. The foaming mold and foaming method according to claim 1, characterized in that: The connecting assembly (6) includes a support plate (61), a mounting plate (62), a rotating rod (63), a connecting arm (64), and an adjusting knob (65). The support plate (61) is symmetrically fixedly mounted on the fixing frame (1), and the mounting plate (62) is symmetrically fixedly mounted on the support plate (61). The mounting plate (62) has a mounting hole and an oblong hole. The length direction of the mounting hole is vertical. The oblong hole is connected to the middle section of the mounting hole, and the center of the oblong hole is located at the top of the mounting hole. A straight hole is opened on one side of the mounting plate (62) that is opposite to each other. The straight hole is located at the bottom of the mounting hole, and the rotating rod (63) passes through the straight hole. One end extends through the lower mold (5) to the outside. One end of the rotating rod (63) is fixedly installed with an adjustment knob (65). The other end of the rotating rod (63) is fixedly installed with one end of the first connecting rod. The other end of the first connecting rod is rotatably connected to one end of the second connecting rod. The first round rod (7) passes through the mounting hole. The second round rod (8) passes through the waist-shaped hole. The first round rod (7) and the second round rod (8) are fixedly installed with the same connecting arm (64). The connecting arm (64) is located between the mounting plates (62). The other end of the second connecting rod is rotatably installed with the middle section of the connecting arm (64). The connecting arm (64) is fixedly installed with the movable frame (3) through a fixed rod.

3. The foaming mold and foaming method according to claim 1, characterized in that: The drive module (2) also includes a hydraulic cylinder (21). One end of the hydraulic cylinder (21) is movably connected to the fixed frame (1), and the other end of the hydraulic cylinder (21) is movably connected to the square frame (9). A rotating shaft (10) is fixedly installed in the middle area of ​​the square frame (9). Multiple bearing seats fixedly installed on the top of the fixed frame (1) are sleeved on the rotating shaft (10). Multiple adjustable pressure rods (11) are provided at the bottom of the square frame (9).

4. The foaming mold and foaming method according to claim 3, characterized in that: The pressure rod (11) includes a sleeve (111) and a bearing rod (112). The bearing rod (112) is inserted inside the sleeve (111). A sliding groove is provided on the inner wall of the sleeve (111). An installation groove is provided on the inner wall of the sleeve (111) from top to bottom. The installation groove is connected to the sliding groove. A slider (12) is provided on the outer wall of the bearing rod (112). The slider (12) is slidably installed in the installation groove. The length direction of the sliding groove is vertical, and the length direction of the installation groove is horizontal. A receiving groove is provided at the bottom of the pressure rod (11). A pressure sensor is provided in the receiving groove.

5. The foaming mold and foaming method according to claim 1, characterized in that: The lower mold (5) includes an inner mold and an outer mold. The outer wall of the inner mold and the interior of the outer mold form a hollow cavity. A temperature control module (13) is installed in the hollow cavity. The temperature control module (13) includes a heat exchange tube, a feed tube and a discharge tube. The hollow cavity has the same shape as the heat exchange tube. The feed tube is connected to one end of the heat exchange tube, and the discharge tube is connected to the other end of the heat exchange tube. The feed tube and the discharge tube are both fixedly installed on the lower mold (5).

6. The foaming mold and foaming method according to claim 1, characterized in that: Includes the following steps: Step S1: Mold closing and locking. After injecting the polyurethane raw material to be foamed into the cavity of the lower mold (5), the moving frame (3) is driven down by the drive module (2) to complete the mold closing between the upper mold (4) and the lower mold (5). Rotate the adjustment knob (65) to lock the upper mold (4) onto the lower mold (5) through the connection module. Step S2: Foaming and molding. Adjust the length of the pressure rod (11) to press against the movable frame (3) and confirm the locking force is up to standard through the pressure sensor. At the same time, adjust the temperature of the lower mold (5) to the temperature range required by the foaming process through the temperature control module (13) and keep it stable until the foaming and molding is completed. Step S3: Open the mold and remove the part. First, loosen the pressure rod (11) and release the auxiliary lock. Then, rotate the adjustment knob (65) in the opposite direction. Through the connecting module, make the upper mold (4) rise vertically to demold and then flip open to remove the formed part.

7. The foaming mold and foaming method according to claim 6, characterized in that: Step S1 further includes: Pre-treatment before mold closing: Before mold closing, the temperature control module (13) is activated to preheat the lower mold (5) so that the surface temperature of the inner mold of the lower mold (5) reaches the initial reaction temperature of the polyurethane raw material. Before injection, the mold cavity inner wall of the upper and lower molds (5) is uniformly sprayed with release agent and the residual foaming material and impurities on the mold closing and bonding surface are wiped clean.

8. The foaming mold and foaming method according to claim 6, characterized in that: Step S2 further includes: Step S21: Locking force grade calibration. Calculate the minimum locking force required based on the grade of the polyurethane raw material to be foamed, the foaming ratio and the mold cavity projection area. Set the locking force target range based on this. After the value fed back by the pressure sensor at the bottom of the pressure rod (11) falls into the target range, rotate the bearing rod (112) to make the slider (12) snap into the corresponding mounting groove to complete the length locking. Step S22: Closed-loop control of mold temperature. Temperature collection points are set up at multiple points such as the corners and center of the cavity of the inner mold of the lower mold (5). The difference between the collected temperature and the set temperature is compared in real time based on the set temperature required by the foaming process. The flow rate and temperature of the constant temperature medium in the heat exchange tube are dynamically adjusted according to the difference.

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