Mold for releasing the stress of a glass fiber reinforced plastic article

Abstract

The application discloses a glass fiber reinforced plastic product demolding stress release mold, which comprises an upper mold assembly and a lower mold assembly, and the upper mold assembly and the lower mold assembly jointly enclose a cavity for forming an injection molded part; a wedge block assembly is arranged on the outer edge of the cavity; the wedge block assembly comprises a wedge block mounting plate, a wedge block, an eccentric shaft and a driving piece; the eccentric shaft is arranged in an offset manner with the wedge block, so that the wedge block synchronously generates posture change and retreat displacement during rotation, and the wedge block mounting plate is driven to move as a whole by cooperating with a retreat driving mechanism, so that a progressive demolding path of first rotating unlocking and then overall retreat is formed. The application can gradually release the lateral tightness of the edge region of the injection molded part, reduce stress concentration and frictional drag in the demolding process, reduce problems such as edge cracking, fiber exposure and deformation, and improve the demolding stability of the complex structure region and the product yield.

Description

Technical Field

[0001] This invention relates to the field of injection molds, and more particularly to a mold for releasing stress in glass fiber reinforced plastic products. Background Technology

[0002] Glass fiber reinforced plastics (GFRPs) are widely used in automotive structural components, electronic and electrical housings, mechanical support components, rail transit components, and industrial composite materials due to their high strength, light weight, good corrosion resistance, and excellent dimensional stability. As the structure of GFRP products becomes increasingly complex and the demand for lightweight construction continues to rise, undercut edges, partial edge banding, deep rib transition zones, and uneven thickness areas are gradually appearing in these products, thus placing higher demands on the molding and demolding processes.

[0003] Currently, glass fiber reinforced plastic products are usually molded using injection molds or compression molds. In order to process complex edge contours, partial undercut structures or lateral forming areas in the mold structure, wedges or lateral core-pulling structures are usually set at the edge of the cavity to limit the edge of the product during the molding stage and remove it from the cavity by lateral retraction during the demolding stage.

[0004] However, most existing wedge structures employ a linear extraction side-pulling method. This means that after the product cools and solidifies, the wedge directly retracts laterally along a predetermined direction to release lateral constraints on the product's edge areas. For ordinary plastic products, this method usually meets basic demolding requirements. However, for glass fiber reinforced plastic products, due to the directional reinforcement properties of glass fibers, the product often exhibits significant anisotropic shrinkage during cooling, especially at undercut edges, reinforcing rib connection areas, thick-walled transition areas, and localized edge-wrapping areas, where the product easily forms a large lateral clamping force with the mold sidewall.

[0005] In this situation, if the wedge is still pulled out using the traditional straight-line forced withdrawal method, the overall retreat will occur before the constraint on the edge of the product is released. This can easily lead to large friction and drag between the wedge and the edge of the product, as well as instantaneous stress concentration. This can cause problems such as cracking, fiber exposure, resin layer peeling, whitening stress marks, local microcracks, or even deformation at the edge of the product, thereby affecting the product's appearance quality, structural integrity, and dimensional consistency. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a stress-relieving mold for demolding glass fiber reinforced plastic products.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A demolding stress relief mold for glass fiber reinforced plastic products includes an upper mold assembly and a lower mold assembly corresponding to the upper mold assembly. The upper mold assembly and the lower mold assembly together enclose a cavity for molding an injection molded part. A wedge assembly is provided on the outer edge of the cavity. The wedge assembly includes a wedge mounting plate, a wedge disposed on the inner side of the wedge mounting plate, an eccentric shaft mounted on one end of the wedge, and a drive component for driving the eccentric shaft to rotate. One side of the wedge is provided with a contact surface for contacting the outer edge of the injection molded part. The eccentric shaft is offset from the center of gravity of the wedge so that when the wedge rotates under the drive of the eccentric shaft, the contact surface changes its posture synchronously and produces a yielding displacement in the direction away from the cavity. The wedge mounting plate is movably mounted on the mold body and connected to a retraction drive mechanism for driving the wedge mounting plate to move away from the cavity. In this process, when the injection molded part is demolded, the driving component first drives the wedge to rotate eccentrically, so that the lateral clamping force between the wedge and the injection molded part is gradually released. Then, the retraction driving mechanism drives the wedge mounting plate to retract as a whole, so that the wedge exits the edge area of ​​the cavity, thereby forming a progressive demolding path of first rotating to unlock and then retracting as a whole.

[0008] Furthermore, the wedge has a notch at one end near the eccentric shaft. The notch provides clearance for the eccentric rotation of the wedge to avoid interference between the wedge and the outer edge of the injection molded part during rotation.

[0009] Furthermore, the notch is any one of an arc-shaped notch, a sloped transition notch, or a composite curved surface notch, and the depth and contour dimensions of the notch are matched and set according to the eccentricity, rotation angle, and edge contour of the wedge block.

[0010] Furthermore, a limiting surface is provided on one side of the inner cavity of the wedge mounting plate. The limiting surface is located on the rotation path of the wedge. After the wedge rotates to a preset angle, its side surface abuts against the limiting surface to limit the maximum rotation angle of the wedge.

[0011] Furthermore, the limiting surface is an inclined surface and is inclined along the rotational tangent direction of the wedge block, so that the wedge block forms a buffering and guiding effect when it approaches the unlocking endpoint.

[0012] Furthermore, a sensing contact is provided on the limiting surface. The sensing contact is connected to the control system of the mold. When the wedge rotates to a preset position and contacts the sensing contact, the control system controls the driving component to stop running and starts the retraction driving mechanism.

[0013] Furthermore, the bottom of the wedge mounting plate is provided with a sliding block, and the mold body is provided with a guide groove for the sliding block to slide and engage. The sliding block can move along the length of the guide groove to drive the wedge mounting plate to move as a whole.

[0014] Furthermore, the retraction drive mechanism includes a screw passing through the inside of the sliding block and a motor that drives the screw to rotate. The sliding block and the screw form a threaded transmission engagement so that the wedge mounting plate is driven to move along the direction of the guide groove by rotating the screw.

[0015] Furthermore, during the process of the wedge switching from the working state to the unlocked state, the rotation angle of the contact surface ranges from 5 to 8 degrees.

[0016] Furthermore, the wedge assembly is provided with multiple wedges, which are arranged in sections along the outer periphery of the cavity.

[0017] Compared to existing technologies, the advantages of this application are as follows: In the initial stage of demolding, the wedge block does not immediately exit the cavity as a whole. Instead, under the action of the driving component, it rotates eccentrically around the eccentric axis, causing the wedge block contact surface to gradually change its posture relative to the edge of the injection molded part. Simultaneously, it generates a micro-displacement away from the cavity, thereby gradually weakening the lateral clamping force between the wedge block and the injection molded part from a strong constraint state, achieving a gradual release of the locking stress in the edge area. Especially for the anisotropic shrinkage problem caused by fiber orientation differences in glass fiber reinforced plastic products, this invention can avoid the stress concentration phenomenon caused by the instantaneous release of local constraints during traditional rigid core pulling processes.

[0018] Secondly, after the wedge completes its eccentric rotation, the wedge mounting plate is moved away from the cavity by the retraction drive mechanism. Since the high-strength contact between the wedge and the injection molded part has been released at this time, the overall withdrawal process of the wedge is more of a low-friction avoidance rather than a forced extraction under a high-tightness state. This can effectively reduce the risk of defects such as cracking, fiber exposure, resin layer peeling, whitening stress marks, local micro-cracks and dimensional deformation in the edge area of ​​glass fiber reinforced plastic products, and improve the demolding integrity and product consistency of complex edge structure areas.

[0019] In addition, by dividing the demolding action into a stress relief stage and an exit avoidance stage, the present invention transforms the originally one-time rigid lateral extraction process into a phased and gradual unlocking process. This not only reduces demolding resistance and the frictional drag between the wedge and the product, but also reduces the impact load and local wear of the wedge assembly during long-term cyclic use, thereby improving the stability and service life of the mold.

[0020] This invention is particularly suitable for glass fiber reinforced plastic products with undercut edges, partial edging, reinforcing rib connection areas, deep rib transition areas, and uneven thickness structures. It can effectively improve the demolding reliability, edge forming integrity, and product qualification rate of complex structural areas. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] Figure 2 This is a cross-sectional schematic diagram of the present invention.

[0024] Figure 3 This is a partial explosion diagram of the present invention.

[0025] Figure 4 This is a schematic diagram showing the interaction between the wedge block assembly of the present invention and the cavity when the wedge block assembly is in working state.

[0026] Figure 5 This is a schematic diagram showing the engagement of the wedge block assembly of the present invention with the cavity when the wedge block assembly is in the unlocked state.

[0027] Figure 6 This is a schematic diagram showing the wedge block assembly of the present invention in the retracted state and its engagement with the cavity.

[0028] Figure 7 This is a schematic diagram showing the interaction between the wedge block and the wedge block mounting plate when the wedge block is in the working state.

[0029] Figure 8 This is a schematic diagram showing the interaction between the wedge block and the wedge block mounting plate when the wedge block is in the unlocked state.

[0030] Figure 9 for Figure 7 A schematic diagram of the cross section along line AA. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Reference Figures 1 to 9 A demolding stress relief mold for glass fiber reinforced plastic products includes an upper mold assembly 10 and a lower mold assembly 20 corresponding to the upper mold assembly 10. The upper mold assembly 10 and the lower mold assembly 20 together enclose a cavity 30 for molding glass fiber reinforced plastic products.

[0033] The upper mold assembly 10 includes an upper mold plate 11, an upper mold core 12 fixedly installed on the lower side of the upper mold plate 11, and a cooling channel 13 disposed inside the upper mold plate 11. The upper mold plate 11 is connected to an external molding device and is used to provide the mounting base for the mold opening and closing movement. The upper mold core 12 is used to form the upper molding surface of the product, and its surface contour is processed according to the product structure. Cooling medium is introduced into the cooling channel 13 to achieve mold temperature control and improve the molding stability of the product.

[0034] The lower mold assembly 20 includes a lower mold plate 21, a lower mold core 22 fixedly installed on the upper side of the lower mold plate 21, and a cooling channel 23 disposed inside the lower mold plate 21. The lower mold core 22 cooperates with the upper mold core 12 to form a cavity 30. The lower mold plate 21 is used to support the ejection mechanism and the guide structure.

[0035] Furthermore, to ensure the opening and closing accuracy of the mold, a guide mechanism 40 is provided between the upper mold assembly 10 and the lower mold assembly 20. The guide mechanism 40 includes guide posts 41 located at the four corners of the lower mold plate 21 and guide sleeves 42 located at corresponding positions on the upper mold plate 11. The guide posts 41 extend into the guide sleeves 42 for sliding engagement, thereby ensuring the coaxiality and positioning accuracy during the mold opening and closing process, and preventing misalignment of the cavity 30 from affecting the product quality.

[0036] In this embodiment, the mold is equipped with an injection mechanism 50. The injection mechanism 50 includes a main channel 51 located in the middle of the upper mold plate 11, a branch channel 52 connected to the main channel 51, and a gate 53 connected to the cavity 30. After the glass fiber reinforced plastic molten material enters the branch channel 52 through the main channel 51, it enters the cavity 30 through the gate 53 to complete the filling and molding.

[0037] Because glass fiber reinforced plastic products have high rigidity and directional shrinkage characteristics after cooling and curing, stress concentration is easily generated due to local constraints during demolding. Therefore, in this embodiment, a demolding mechanism 60 is provided inside the lower mold assembly 20. The demolding mechanism 60 includes an ejector pin fixing plate 61, an ejector pin mounting plate 62, multiple ejector pins 63, and an ejection plate that drives the ejector pins to move. Multiple ejector pins 63 are disposed inside the lower mold core 22 and are arranged corresponding to the stress area of ​​the product, and are used to eject the product from inside the cavity 30 after the mold is opened.

[0038] Specifically, ejector pins 63 are preferably positioned in areas where the stress on the product is relatively uniform, at the root of the reinforcing ribs, and in thick-walled transition areas, thereby avoiding localized cracking of the glass fiber reinforced plastic product caused by single-point stress. The ejector pin fixing plate 61 is connected to the ejector pin mounting plate 62, and the ejector plate moves upward under the action of external ejection power to drive multiple ejector pins 63 to move upward synchronously, thereby achieving product demolding.

[0039] Furthermore, in order to reduce the impact of residual gas inside the glass fiber reinforced plastic product on the molding quality, the mold body 1 is provided with an exhaust mechanism 70. The exhaust mechanism 70 includes an exhaust channel 71 located at the edge of the cavity 30. During the mold closing injection or molding process, the gas inside the cavity 30 is discharged through the exhaust channel 71, thereby reducing bubbles, insufficient glue and scorching.

[0040] In this embodiment, a wedge assembly 80 is provided at the outer edge of the cavity 30. The wedge assembly 80 includes a wedge mounting plate 81, a wedge 82 disposed inside the wedge mounting plate 81, and an eccentric shaft 83 mounted on one end of the wedge 82. The end of the eccentric shaft 83 away from the wedge 82 is connected to a drive member 84. The drive member 84 is mounted on the inner wall of the wedge mounting plate 81. The wedge 82 has a contact surface 82a on one side. When the wedge 82 is in the working state, the contact surface 82a is close to the inner wall of the cavity 30. The shape of the contact surface 82a can be freely set and depends on the shape of the outer edge of the injection molded part 90 inside the cavity 30. In addition, the end of the wedge 82 near the eccentric shaft 83 has a notch 82b. The notch 82b is used to provide clearance space for the eccentric rotational movement of the wedge 82 and reduce the risk of structural interference of the wedge 82 during the rotation unlocking process. Preferably, the notch 82b can be configured as an arc-shaped notch, a sloped transition notch, or a composite curved surface notch. Its specific shape can be adaptively adjusted according to the rotation trajectory of the wedge 82 and the surrounding structure of the cavity 30 to ensure that the wedge 82 has sufficient room for movement during rotation. When the drive member 84 drives the wedge 82 to rotate, the notch 82b can ensure that the side of the wedge 82 will not extend into the cavity 30 and contact the outer edge of the injection molded part 90, thereby avoiding secondary compression or scratching of the injection molded part 90 due to accidental intrusion of the non-contact area into the cavity 30 during eccentric rotation of the wedge 82.

[0041] Specifically, during the transition from the working state to the unlocked state, the wedge 82 rotates around the eccentric shaft 83. Since the eccentric rotation trajectory has a certain arc-shaped path, if the overall outer contour of the wedge 82 is not designed to avoid this, its edge region near the eccentric shaft 83 is prone to swinging towards the cavity 30 during rotation, thus causing local interference with the outer edge of the injection molded part 90. Especially when the glass fiber reinforced plastic product 90 has already cured, has high surface rigidity, and a brittle edge structure, this local interference can easily lead to quality problems such as scratches, chipping, exposed fibers, whitening stress marks, or microcracks on the product edges.

[0042] Therefore, in this embodiment, by providing a notch 82b at one end of the wedge 82 near the eccentric shaft 83, a local avoidance area is formed when the wedge 82 rotates, thereby allowing the motion envelope of the wedge 82 to avoid the boundary area of ​​the cavity 30. In other words, the notch 82b is equivalent to "edge-cutting" the rotation trajectory of the wedge 82, so that during rotation, the wedge 82 gradually detaches from the injection molded part 90 only through the contact surface 82a along a predetermined trajectory, while the remaining sidewall areas always maintain a safe gap with the injection molded part 90.

[0043] Furthermore, the depth and contour dimensions of the notch 82b can be designed to match the eccentricity of the wedge 82, the rotation angle, and the edge contour shape of the injection molded part 90, to ensure that the wedge 82 does not interfere with the injection molded part 90 throughout the entire rotation unlocking stroke. Preferably, the contour edge of the notch 82b is set as a rounded transition structure to reduce stress concentration and reduce the risk of fatigue damage to the wedge 82 due to sharp corner stress during long-term reciprocating motion.

[0044] Furthermore, the wedge 82 is rotatably mounted inside the wedge mounting plate 81 via the eccentric shaft 83. The axis of the eccentric shaft 83 is offset from the center of gravity of the wedge 82, that is, there is a preset eccentric distance between the eccentric shaft 83 and the geometric center of the wedge 82. This allows the wedge 82 to rotate under the drive of the eccentric shaft 83, and its contact surface 82a not only changes angle but also simultaneously generates a micro-displacement in the direction away from the cavity 30, thereby realizing a compound unlocking action of rotation and retraction.

[0045] Specifically, the drive component 84 is used to drive the eccentric shaft 83 to rotate. In this embodiment, the drive component 84 can be a conventional drive structure such as a cylinder, electric push rod, servo motor, hydraulic drive assembly, or rotary actuator with a reduction mechanism. Preferably, the drive component 84 is a servo motor, which is connected to the eccentric shaft 83 through a reducer to achieve small-angle swing control of the eccentric shaft 83. When the drive component 84 is working, it drives the eccentric shaft 83 to rotate around its own axis at a preset angle, thereby driving the wedge block 82 to rotate eccentrically.

[0046] When the mold is closed, the wedge 82 is in operation, with its contact surface 82a close to the inner wall of the cavity 30 and corresponding to the outer edge of the injection molded part 90. This wedge limits and shapes the local contour area of ​​the injection molded part 90, forming a predetermined shape at the edge. Especially in glass fiber reinforced plastic products with undercut edges, partial edging, deep rib transition areas, or complex contour areas, the wedge 82 can provide lateral forming support at the corresponding positions.

[0047] When the injection molded part 90 completes cooling and solidification and enters the demolding stage, the drive component 84 first drives the eccentric shaft 83 to rotate. The eccentric shaft 83 drives the wedge block 82 to rotate eccentrically, causing the contact surface 82a of the wedge block 82 to gradually deviate from the inner wall of the cavity 30 and gradually separate from the outer edge of the injection molded part 90. Because the eccentric shaft 83 is eccentrically set, the wedge block 82 simultaneously generates a retraction displacement away from the cavity 30 during the rotation process. Therefore, compared with the traditional straight core-pulling wedge block structure, the wedge block 82 in this embodiment does not directly detach from the product, but first reduces the edge clamping force by rotation, and then gradually releases the local locking stress through eccentric displacement. This avoids problems such as edge cracking, fiber layer peeling, stress whitening, or deformation of the glass fiber reinforced plastic product 90 due to the rapid release of local constraints at the moment of demolding.

[0048] As a further improvement of this embodiment, the inner cavity of the wedge mounting plate 81 has a limiting surface 85 on one side. The limiting surface 85 is an inclined surface, which is located on the rotation path of the wedge 82. After the wedge 82 rotates at a certain angle, the side of the wedge 82 will abut against the limiting surface 85, thereby preventing the wedge 82 from rotating further.

[0049] Specifically, the limiting surface 85 is preferably located at the position corresponding to the end point of the wedge block 82's rotation, and is inclined along the rotational tangent direction of the wedge block 82, so that the wedge block 82 gradually contacts the limiting surface 85 as it approaches the unlocking end point, rather than experiencing an instantaneous rigid collision. By setting the limiting surface 85 as an inclined surface, the wedge block 82 can form a buffering and guiding effect during contact with the limiting surface 85, thereby reducing the impact load when the wedge block 82 stops rotating, reducing the force fluctuation of the eccentric shaft 83 and the driving component 84, and improving the stability of the wedge block assembly 80 during long-term cyclic operation.

[0050] Furthermore, the tilt angle of the limiting surface 85 can be adaptively adjusted according to the eccentric trajectory of the wedge block 82 and the unlocking angle, so that the wedge block 82 can stably maintain the preset unlocking posture at the final stop position, preventing the swing phenomenon caused by inertia from re-contacting the edge area of ​​the injection molded part 90.

[0051] To prevent damage to the drive component 84, a sensing contact 86 is provided at a specific position on the limiting surface 85. The drive component 84 is signal-connected to the sensing contact 86. When the wedge block 82 rotates a certain angle, the side of the wedge block 82 will abut against the sensing contact 86 on the limiting surface 85, and the mold control system will control the drive component 84 to stop running. Preferably, the sensing contact 86 can be a pressure-triggered sensing plate, limit switch, proximity sensor, micro-motion contact, or Hall effect sensor, etc., and its function is to monitor in real time whether the wedge block 82 has reached the preset unlocking position.

[0052] In this embodiment, during the transition from the working state to the unlocked state, the rotation angle α of the contact surface 82a of the wedge 82 ranges from 5 to 8 degrees. Experiments have shown that when the rotation angle α is less than 5 degrees, the lateral clamping force between the wedge 82 and the injection molded part 90 is insufficiently released, and the injection molded part 90 is still easily subject to edge constraints during demolding. While when the rotation angle α exceeds 8 degrees, although the release space can be further increased, the rotational displacement of the wedge 82 increases, easily causing the local edge of the wedge 82 to intrude into the movement area of ​​other structures, and simultaneously increasing the load on the eccentric shaft 83 and the drive component 84. Therefore, controlling the rotation angle α of the contact surface 82a within the range of 5 to 8 degrees ensures sufficient relief of demolding stress while also considering the stability and efficiency of the mechanism.

[0053] In addition, the bottom of the wedge mounting plate 81 is provided with a retraction drive mechanism, which includes a sliding block 87. The sliding block 87 is installed in the guide groove 88 formed between the upper mold core 12 and the lower mold core 22. The sliding block 87 can slide along the length of the guide groove 88, thereby driving the wedge mounting plate 81 to move as a whole. The guide groove 88 is preferably set as a dovetail groove, a T-shaped guide groove, or a rectangular limiting guide groove structure to improve the guiding accuracy and anti-sway capability of the wedge mounting plate 81 during movement.

[0054] Furthermore, a screw 89 is inserted into the sliding block 87, forming a threaded drive engagement with the sliding block 87. One end of the screw 89 extends outside the mold and is connected to a motor 810. The motor 810 drives the screw 89 to rotate, thereby moving the sliding block 87 and the wedge mounting plate 81 along the guide groove 88. Preferably, the motor 810 is a servo motor or a stepper motor to facilitate precise control of the retraction distance and movement speed of the wedge mounting plate 81.

[0055] After the mold completes the mold opening action, the wedge block assembly 80 first enters the stress relief stage, that is, the drive component 84 starts first, driving the eccentric shaft 83 to rotate, causing the wedge block 82 to rotate eccentrically around the eccentric shaft 83 by 5 to 8 degrees, so that the contact surface 82a gradually deviates from the edge area of ​​the injection molded part 90, reducing the edge clamping force and achieving initial unlocking.

[0056] After the wedge 82 rotates to the preset angle, the side of the wedge 82 contacts the sensing contact 86. After the control system receives the position signal, the control drive 84 stops working and starts the motor 810. The motor 810 drives the screw 89 to rotate. The screw 89 pushes the sliding block 87 to move along the guide groove 88 away from the cavity 30, thereby driving the wedge mounting plate 81 and the wedge 82 to retract as a whole.

[0057] It should be noted that in this embodiment, the wedge 82 does not directly use a traditional side-pulling structure for linear removal, but rather adopts a composite motion method of first rotating to unlock and then retracting as a whole. Specifically, during the rotation phase of the wedge 82, the local clamping stress in the edge area of ​​the injection molded part 90 is released first by the small-angle deflection of the contact surface 82a, so that the contact between the wedge 82 and the injection molded part 90 gradually changes from surface contact to a gap state; then, the motor 810 drives the wedge mounting plate 81 to move backward as a whole, thereby completely removing the wedge 82 from the side area of ​​the cavity 30.

[0058] Compared to the traditional direct transverse core-pulling method, the wedge assembly 80 in this embodiment can avoid edge tearing or fiber layer peeling caused by the forced removal of the wedge 82 under high clamping force. It is especially suitable for glass fiber reinforced plastic products 90 with uneven local shrinkage caused by differences in fiber orientation, thereby realizing a demolding path of stress pre-release, gradual unlocking, and overall yielding, effectively reducing demolding resistance and improving the demolding integrity and product consistency of complex edge structure areas.

[0059] Furthermore, after the wedge block 82 completes its eccentric rotation and unlocks, and the wedge block mounting plate 81 retracts to its preset position, the ejector pin 63 in the demolding mechanism 60 ejects the injection molded part 90, thus achieving a gradual demolding process of "side stress relief - partial unlocking - overall ejection". Through this structural design, the stress concentration phenomenon of the glass fiber reinforced plastic product 90 during demolding can be effectively reduced, making the force on the injection molded part 90 more uniform, improving the demolding stability of complex structural areas and the integrity of the product edges.

[0060] After demolding and removal of the injection molded part 90, the wedge block 82 needs to be restored from the unlocked state to the working state to ensure that the mold can enter the next molding cycle. In this embodiment, the reset process of the wedge block 82 corresponds to the demolding process, and is carried out by first retracting and resetting, and then rotating and locking.

[0061] Specifically, during the demolding stage, the wedge 82 first rotates under the action of the drive member 84 to release the contact relationship with the outer edge of the injection molded part 90. Then, the motor 810 starts and drives the screw 89 to rotate, causing the sliding block 87 to move along the guide groove 88 in a direction away from the cavity 30, thereby driving the wedge mounting plate 81 and the wedge 82 to retract as a whole.

[0062] When the injection molded part 90 is ejected and removed, the motor 810 runs in reverse and drives the screw 89 to rotate in reverse. Since the sliding block 87 and the screw 89 form a transmission fit, the sliding block 87 moves along the guide groove 88 toward the direction close to the cavity 30, thereby driving the wedge mounting plate 81 and the wedge block 82 as a whole to reset toward the cavity 30.

[0063] During this process, the wedge 82 remains unlocked, meaning it retains its rotated angular posture, preventing premature interference between the wedge 82 and the edge area of ​​the cavity 30 during the overall forward movement. Once the wedge mounting plate 81 reaches the preset position, the drive component 84 reverses its movement, causing the eccentric shaft 83 to rotate in the opposite direction. The eccentric shaft 83 then drives the wedge 82 to rotate in the opposite direction, causing the contact surface 82a of the wedge 82 to rotate back towards the inner wall of the cavity 30 and return to its initial working position.

[0064] Once the wedge 82 rotates to the working state, the drive component 84 stops operating, and the wedge 82 completes its reset. At this time, the contact surface 82a of the wedge 82 moves closer to the inner wall of the cavity 30 to limit and shape the outer edge area of ​​the injection molded part 90 after the next mold closing.

[0065] It should be noted that, in order to restore the contact surface 82a of the wedge 82 to its initial working position, the drive component 84 is preset with an initial position corresponding to the working state of the wedge 82, and the initial position corresponds to the initial rotation angle of the eccentric shaft 83. When the mold enters the reset stage, the drive component 84 runs in reverse and drives the eccentric shaft 83 to rotate toward the initial position. When the drive component 84 reaches the initial position, the drive component 84 stops running, thereby restoring the eccentric shaft 83 to its initial angle state and driving the wedge 82 to return to its working state.

[0066] Since the eccentric shaft 83 and the wedge block 82 are fixedly connected, when the eccentric shaft 83 returns to the initial angle, the posture of the wedge block 82 is restored synchronously. The contact surface 82a of the wedge block 82 approaches the inner wall of the cavity 30 again and returns to the position corresponding to the outer edge of the injection molded part 90, so as to limit the molding of the outer edge area of ​​the injection molded part 90 after the next mold closing.

[0067] Preferably, the initial position of the drive component 84 can be set by preset stroke, angle parameters or origin position to ensure that the wedge block 82 can stably return to the same working posture each time it is reset, thereby improving the repeatability of the wedge block 82 and the molding consistency of the edge area of ​​the cavity 30.

[0068] Through the above reset method, the wedge block 82 first restores its overall position and then its posture during the reset process, thereby ensuring that the wedge block 82 can accurately return to the working state and provide stable side support for the next injection molding cycle.

[0069] Preferably, multiple wedge assemblies 80 can be arranged along the outer periphery of the cavity 30, and the multiple wedges 82 can be arranged in zones according to the edge stress characteristics of the injection molded part 90. For example, more wedges 82 can be arranged in the position where the injection molded part 90 is prone to shrinkage and clamping, while the number of wedges 82 can be reduced in the area with less stress, so as to achieve localized stress directional relief.

[0070] In this embodiment, through the synergistic action of the wedge 82, the eccentric shaft 83 and the driving component 84, the wedge 82 is changed from the traditional rigid extraction method to the eccentric rotation slow release method, so that the constraint stress at the edge of the cavity 30 can be gradually released. This is particularly suitable for the anisotropic shrinkage scenario caused by fiber orientation in glass fiber reinforced plastic products 90, thereby effectively improving the demolding quality and product qualification rate.

[0071] In this embodiment, the wedge 82 adopts a compound motion of first rotating and then retracting. This not only enables the wedge 82 to exit the cavity 30, but also gradually releases the demolding stress in the edge area of ​​the glass fiber reinforced plastic product 90 during the exit process, thereby reducing the local damage problem that is easily caused by the traditional side core pulling structure.

[0072] Specifically, after the glass fiber reinforced plastic product 90 has cooled and solidified, due to the uneven distribution of glass fiber orientation and the uneven shrinkage of the resin matrix, the injection molded part 90 usually forms a certain degree of clamping effect on the edge of the cavity 30, especially at the undercut edge, the reinforcing rib connection area, the local edge wrapping area, and the area of ​​abrupt change in wall thickness. A large lateral clamping force is often formed between the injection molded part 90 and the wedge 82. Traditional lateral core-pulling wedges generally retreat directly in a straight line along the lateral direction, forcibly pulling away before the wedge has released its lateral constraint. At this time, a large frictional dragging effect is easily formed between the wedge and the injection molded part 90, causing instantaneous stress concentration at the edge of the injection molded part 90.

[0073] For glass fiber reinforced plastic products 90, due to the directional reinforcement characteristics of the internal glass fibers, when a local area is subjected to a sudden change in transverse tensile stress, problems such as edge cracking, fiber pull-out, resin layer peeling, whitening stress marks, microcracks, or even local delamination are very likely to occur. Therefore, the simple transverse extraction method is not suitable for the stable demolding of high rigidity glass fiber reinforced plastic products.

[0074] Based on this, the wedge 82 in this embodiment does not immediately retract after mold opening. Instead, it first rotates at a small angle around the eccentric shaft 83 under the action of the drive component 84, causing the contact surface 82a to change its posture first. Since the eccentric shaft 83 is eccentrically arranged, the wedge 82 not only changes its angle when rotating, but also undergoes a slight retraction displacement. Therefore, the contact relationship between the contact surface 82a and the edge of the injection molded part 90 will gradually change from the original surface pressing state to a local point contact state, eventually forming a gap state. The lateral clamping force that was originally concentrated between the wedge 82 and the injection molded part 90 will gradually decrease as the posture of the contact surface 82a changes, allowing the internal stress in the edge area to be released first, thereby avoiding direct rigid separation under high constraint.

[0075] Especially when the contact surface 82a of the wedge 82 rotates only 5 to 8 degrees, the wedge 82 does not immediately and completely leave the cavity 30. Instead, it first forms a small release gap, which allows the edge of the injection molded part 90 to have a certain degree of elastic rebound space. Since the glass fiber reinforced plastic product 90 still has a small amount of residual stress after cooling, as the edge constraint gradually decreases, the injection molded part 90 can undergo slight deformation compensation, allowing the locking stress that was originally concentrated in the local edge area to be released in advance.

[0076] After the wedge 82 completes its rotational unlocking, the control system restarts the motor 810, driving the wedge mounting plate 81 to retract as a whole away from the cavity 30. At this time, since the high-strength contact between the wedge 82 and the injection molded part 90 has been released, the overall retraction of the wedge 82 is more of a low-friction release than a traditional forced side pull. When the wedge 82 moves as a whole, the edge of the injection molded part 90 is no longer subject to significant clamping, so there will be no obvious dragging or scratching due to the lateral displacement of the wedge 82, thus effectively reducing the risk of damage to the edge area.

[0077] Furthermore, from the perspective of the demolding path, the wedge 82 adopts a method of first rotating and then retracting, which is equivalent to splitting the originally one-time rigid demolding action into two stages: The first stage is the stress relief stage, in which the edge constraint force of the injection molded part 90 is gradually weakened by the small-angle eccentric rotation of the wedge 82. The second stage is the exit and avoidance stage. After the edge stress has been released, the wedge block 82 moves away from the cavity 30 as a whole, achieving safe exit.

[0078] Therefore, the wedge assembly 80 in this embodiment can change the relationship between the wedge 82 and the injection molded part 90 from a strong constraint direct separation relationship to a weak constraint gradual separation relationship. Especially when the glass fiber reinforced plastic product 90 has a complex edge contour, high glass fiber content, local undercut or uneven thickness area, this composite action can significantly reduce the demolding breakage rate, improve the edge molding integrity and product dimensional stability.

[0079] In addition, since the rotation of the wedge 82 occurs before the overall retraction, the wedge 82 can avoid scratches caused by direct tangential contact with the edge of the injection molded part 90 during the retraction process, making the exit trajectory of the wedge 82 smoother and further improving the reliability of the mold's long-term stable operation and the product yield.

[0080] The working process of this embodiment is as follows: First, the upper mold assembly 10 and the lower mold assembly 20 are closed by an external injection molding equipment or molding equipment, so that the upper mold core 12 and the lower mold core 22 cooperate to form a cavity 30; then, the glass fiber reinforced plastic molten material is injected into the cavity 30 through the injection mechanism 50, and the filling molding and cooling solidification are completed under preset temperature and pressure conditions.

[0081] After the injection molded part 90 has cured, the upper mold assembly 10 and the lower mold assembly 20 separate, and the mold enters the mold opening state. After the mold opens, the drive component 84 first drives the eccentric shaft 83 to rotate, causing the wedge block 82 to rotate. The contact surface 82a of the wedge block 82 gradually deviates from the outer edge of the injection molded part 90 to release the local constraint stress in the edge area of ​​the injection molded part 90. Subsequently, the motor 90 starts and drives the screw 89 to rotate, causing the sliding block 87 to move along the guide groove 88, which in turn drives the wedge block mounting plate 81 and the wedge block 82 as a whole to retract away from the cavity 30, so that the wedge block 82 exits the edge area of ​​the cavity 30.

[0082] After the wedge 82 is completely withdrawn, the demolding mechanism 60 drives the ejector pin 63 to eject the injection molded part 90, thus demolding the injection molded part 90. After the injection molded part 90 is removed, the motor 90 runs in reverse, driving the wedge mounting plate 81 and the wedge 82 to reset as a whole. Then, the drive component 84 reverses its movement, restoring the wedge 82 to its working state for the next injection molding cycle.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A mold for releasing stress of glass fiber reinforced plastic products, comprising an upper mold assembly (10) and a lower mold assembly (20) corresponding to the upper mold assembly (10), wherein the upper mold assembly (10) and the lower mold assembly (20) together enclose a cavity (30) for molding an injection molded part (90). Its features are, The outer edge of the cavity (30) is provided with a wedge assembly (80), the wedge assembly (80) includes a wedge mounting plate (81), a wedge (82) disposed inside the wedge mounting plate (81), an eccentric shaft (83) mounted on one end of the wedge (82), and a drive member (84) for driving the eccentric shaft (83) to rotate. The wedge (82) has a contact surface (82a) on one side for contacting the outer edge of the injection molded part (90). The eccentric shaft (83) is offset from the center of gravity of the wedge (82) so that when the wedge (82) rotates under the drive of the eccentric shaft (83), the contact surface (82a) changes its posture synchronously and produces a yielding displacement in the direction away from the cavity (30). The wedge mounting plate (81) is movably mounted on the mold body and connected to a retraction drive mechanism for driving the wedge mounting plate (81) to move away from the cavity (30). When the injection molded part (90) is demolded, the driving member (84) first drives the wedge (82) to rotate eccentrically, so that the lateral clamping force between the wedge (82) and the injection molded part (90) is gradually released. Then the retraction driving mechanism drives the wedge mounting plate (81) to retract as a whole, so that the wedge (82) exits the edge area of ​​the cavity (30), thereby forming a progressive demolding path of first rotating to unlock and then retracting as a whole.

2. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 1, characterized in that, The wedge (82) has a notch (82b) at one end near the eccentric shaft (83). The notch (82b) is used to provide clearance space for the eccentric rotation of the wedge (82) so as to avoid interference between the wedge (82) and the outer edge of the injection molded part (90) during rotation.

3. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 2, characterized in that, The notch (82b) is any one of an arc notch, a slope transition notch, or a composite curved surface notch, and the depth and contour dimensions of the notch (82b) are matched and set according to the eccentricity and rotation angle of the wedge (82) and the edge contour of the injection molded part (90).

4. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 1, characterized in that, The wedge mounting plate (81) has a limiting surface (85) on one side of its inner cavity. The limiting surface (85) is located on the rotation path of the wedge (82). After the wedge (82) rotates to a preset angle, its side surface abuts against the limiting surface (85) to limit the maximum rotation angle of the wedge (82).

5. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 4, characterized in that, The limiting surface (85) is an inclined surface and is inclined along the rotational tangent direction of the wedge (82) so that the wedge (82) forms a buffer guiding effect when it approaches the unlocking end point.

6. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 4, characterized in that, The limiting surface (85) is provided with a sensing contact (86), which is connected to the control system of the mold. When the wedge (82) rotates to the preset position and contacts the sensing contact (86), the control system controls the driving component (84) to stop running and starts the retraction driving mechanism.

7. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 1, characterized in that, The bottom of the wedge mounting plate (81) is provided with a sliding block (87), and the mold body is provided with a guide groove (88) for the sliding block (87) to slide and engage. The sliding block (87) can move along the length direction of the guide groove (88) to drive the wedge mounting plate (81) to move as a whole.

8. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 7, characterized in that, The retraction drive mechanism includes a screw (89) passing through the inside of the sliding block (87) and a motor (810) that drives the screw (89) to rotate. The sliding block (87) and the screw (89) form a threaded transmission engagement so as to drive the wedge mounting plate (81) to move along the direction of the guide groove (88) by rotating the screw (89).

9. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 1, characterized in that, During the process of switching the wedge (82) from the working state to the unlocked state, the rotation angle of the contact surface (82a) ranges from 5 to 8 degrees.

10. The demolding stress relief mold for glass fiber reinforced plastic products according to claim 1, characterized in that, The wedge assembly (80) is provided with multiple wedges (82), which are arranged in sections along the outer periphery of the cavity (30).

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