Anti-overflow plastic injection molding device and method

Abstract

The invention relates to the technical field of injection molding, in particular to an anti-overflow plastic injection molding device and method. The device comprises a base, a blanking piece is arranged on the top of the base close to one end, a vertical plate is fixedly connected to the top of the base close to the middle, an injection molding assembly is arranged between the vertical plate and the blanking piece, and a forming assembly is arranged between the outer wall of the side, away from the blanking piece, of the vertical plate and the top of the base; the forming assembly comprises a mold which is fixedly connected to the outer wall of the side, away from the discharging piece, of the vertical plate. A compression molding assembly is arranged at the end, away from the discharging piece, of the top of the base and comprises a compression molding head, and the compression molding head is movably connected into the mold. The injection molding assembly is used for extruding a material in a blanking piece into the mold, the forming assembly is used for cooling a high-temperature material, the compression molding head is used for extruding the material in the mold, the material in the mold expands in a high-temperature state to push the compression molding head to contract, and the contraction force of the compression molding head increases the cooling speed of the forming assembly.

Description

Technical Field

[0001] The invention relates to the technical field of injection molding, in particular to an overflow-proof plastic injection molding device and method. Background Art

[0002] The injection molding machine is a main molding equipment that uses plastic molding molds to make plastic products of various shapes from thermoplastics or thermosetting plastics. The working principle of the injection molding machine is a cyclic process. First, plastic particles or powders are quantitatively fed into the heated barrel from the hopper, then the barrel is heated and the screw rotates to melt and plasticize the plastic. Then, the screw is pushed by the injection cylinder piston to inject the molten plastic into the closed mold cavity through the nozzle at high pressure and high speed. After that, the plastic in the cavity is filled and cooled, changing from a viscous state to a solid state. Finally, the mold is opened and the product is taken out through the ejection device to complete one injection molding. Then the cycle is repeated. The process requires the coordination of various systems.

[0003] In existing plastic injection molding, different plastic materials will expand to a large extent during the heating process. If the thermal expansion characteristics of the material are not adequately considered during the injection molding process, when the plastic melt is heated to a higher temperature, its volume expansion may exceed the accommodation range of the mold cavity, thereby causing overflow from the parting surface and other parts; at the same time, for some plastics with special fillers or additives added, their thermal expansion behavior may also change; for example, plastics with added reinforcing materials such as glass fiber may produce uneven expansion when heated due to the difference in thermal expansion of each component, thereby increasing the risk of overflow.

[0004] In view of this, the present invention provides an overflow-proof plastic injection molding device and method. Summary of the invention

[0005] The object of the present invention is to provide an overflow-proof plastic injection molding device and method to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned object, one of the objects of the present invention is to provide an anti-overflow plastic injection molding device, comprising a base, a material discharge piece is provided on the top of the base near one end thereof, a vertical plate is fixedly connected to the top of the base near the middle, an injection molding component is provided between the vertical plate and the material discharge piece, and a molding component is provided between the outer wall of the vertical plate on one side away from the material discharge piece and the top of the base; The molding assembly includes a mold, and the mold is fixedly connected to the outer wall of the side of the vertical plate away from the blanking piece; a compression molding assembly is provided at one end of the top of the base away from the blanking piece, and the compression molding assembly includes a compression molding head, and the compression molding head is movably connected inside the mold; The injection molding component is used to extrude the material in the blank into the mold, the molding component is used to cool the high-temperature material, and the compression molding head is used to extrude the material inside the mold. The material inside the mold expands at a high temperature and pushes the compression molding head to contract. The contraction force of the compression molding head increases the cooling speed of the molding component.

[0007] As a further improvement of the present technical solution, the injection molding assembly includes an injection molding tube, which is fixedly connected to the inside of the blanking piece. The end of the injection molding tube away from the vertical plate is fixedly connected to an injection molding machine. A screw is provided inside the injection molding machine, and the screw is located inside the injection molding tube.

[0008] As a further improvement of the technical solution, the molding assembly also includes a circulation pump, which is fixedly connected to the top of the base at the bottom of the injection tube, and two hoses are fixedly connected between the circulation pump and the mold.

[0009] As a further improvement of the technical solution, the compression molding assembly also includes a support plate, which is fixedly connected to one end of the top of the base away from the blanking piece, and a cylinder is fixedly connected inside the support plate.

[0010] As a further improvement of the technical solution, a compression molding head is fixedly connected to the end of the cylinder piston rod, guide columns are provided near the four corners between the support plate and the vertical plate, and the compression molding head is movably connected between the outer walls of the four guide columns.

[0011] As a further improvement of the technical solution, the compression molding head includes a fixed plate, which is fixedly connected to the end of the cylinder piston rod. A pressure plate is provided between the fixed plate and the inside of the mold, and an elastic member is fixedly connected between the pressure plate and the fixed plate.

[0012] A second object of the present invention is to provide a method for operating an anti-overflow plastic injection molding device including any one of the above, comprising the following method steps: S1. First, start the injection molding component to fully mix and stir the materials inside the blank, and heat them at high temperature, and then press the materials into the mold through the injection molding component; S2, the compression molding head is pressed into the mold by the expansion and contraction of the compression molding component. When the material inside the mold expands, the compression molding head is driven to contract. S3. When the compression molding head shrinks, the cooling speed of the molding component will be accelerated, and the expanded material inside the mold will be cooled and shrunk to prevent the material inside the mold from expanding too fast and causing overflow; S4. When the material inside the mold shrinks due to cooling and slowing down of the injection molding flow rate, the compression molding head will rebound and continue to press inside the mold, increasing the cooling speed and speeding up the injection molding flow rate, making it convenient to continue to press the material into the mold, and this reciprocating process ensures the quality of plastic injection molding.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. In the anti-overflow plastic injection molding device and method, when the material in a high-temperature expansion state is input into the mold, if its expansion degree exceeds the accommodation range of the mold, a strong thrust will be generated; this thrust will act on the compression molding head, causing the compression molding head to shrink; this contraction force will increase the distance between the compression molding head and the mold. Due to the circulation characteristics of the coolant in the molding component, the increase in the distance between the compression molding head and the mold means that the coolant circulation distance also increases, which greatly improves the cooling speed of the molding component.

[0014] 2. In the anti-overflow plastic injection molding device and method, when the material shrinks due to cooling inside the mold, the compression molding head will rebound under the action of the elastic restoring force, and the compression molding head will appropriately squeeze the material; this squeezing action will gradually reduce the distance between the compression molding head and the mold, thereby slowing down the cooling speed; it is convenient to automatically and accurately adjust the cooling speed of the molding component according to the degree of expansion of the material during the injection molding process, effectively avoiding the occurrence of material overflow during the entire molding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the injection molding structure of the present invention; Figure 3 It is a schematic diagram of the slow cooling structure of the present invention; Figure 4 It is a schematic diagram of the rapid cooling structure of the present invention; Figure 5 It is a schematic diagram of the structure of the injection molding component of the present invention; Figure 6 It is a schematic diagram of the structure of the molding assembly of the present invention; Figure 7 It is a schematic diagram of the structure of the compression molding component of the present invention; Figure 8 It is a schematic diagram of the structure of the compression molding head of the present invention.

[0016] The meaning of each number in the figure is: 1. Base; 11. Cutting parts; 12. Injection molding assembly; 120. Injection molding tube; 121. Screw; 122. Injection molding machine; 13. Molding assembly; 130. Mold; 131. Hose; 132. Circulation pump; 14, compression molding assembly; 140, support plate; 141, cylinder; 142, guide column; 143, compression molding head; 1430, fixed plate; 1431, pressure plate; 1432, elastic member; 15. Stand board. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0019] Example 1, please refer to Figure 1-Figure 4 As shown, the purpose of this embodiment is to provide an anti-overflow plastic injection molding device, including a base 1, a blanking piece 11 is provided on the top of the base 1 near one end thereof, a vertical plate 15 is fixedly connected to the top of the base 1 near the middle, an injection molding component 12 is provided between the vertical plate 15 and the blanking piece 11, and a molding component 13 is provided between the outer wall of the vertical plate 15 on one side away from the blanking piece 11 and the top of the base 1; The molding assembly 13 includes a mold 130, which is fixedly connected to the outer wall of the vertical plate 15 away from the blanking piece 11; a compression molding assembly 14 is provided at one end of the top of the base 1 away from the blanking piece 11, and the compression molding assembly 14 includes a compression molding head 143, which is movably connected to the inside of the mold 130; The injection molding component 12 is used to extrude the material in the blank 11 into the mold 130, the molding component 13 is used to cool the high-temperature material, and the compression molding head 143 is used to extrude the material inside the mold 130. The material inside the mold 130 expands at a high temperature and pushes the compression molding head 143 to contract. The contraction force of the compression molding head 143 increases the cooling speed of the molding component 13.

[0020] The improvement of this embodiment is that: during the injection molding process, the injection molding assembly 12 first stirs the material in the lower material 11, and then transports the material into the mold 130; since the injection molding material needs to be heated at high temperature for stirring and mixing, the material is easy to expand at high temperature; when the expanded material enters the mold 130, it pushes the compression molding head 143 to shrink; When the compression molding head 143 shrinks due to the expansion of the material, the distance between the compression molding head 143 and the mold 130 increases, which makes the coolant circulation distance of the molding component 13 larger, thereby increasing the cooling speed of the molding component 13 and accelerating the cooling of the material in the mold 130; after the material is cooled, the expansion degree is reduced and it shrinks, avoiding overflow due to expansion; When the material cools and shrinks, the compression molding head 143 rebounds to extrude the material, reducing the distance between the compression molding head 143 and the mold 130, thereby reducing the cooling rate of the molding component 13, avoiding excessive cooling of the material before the injection molding is complete, and facilitating continuous injection molding into the mold 130; in this way, the cooling rate and injection flow rate can be adjusted according to the degree of material expansion to prevent the material from overflowing during the molding process.

[0021] First, the specific structure of the injection molding assembly 12 is disclosed. The injection molding assembly 12 includes an injection molding tube 120. The injection molding tube 120 is fixedly connected to the inside of the blanking piece 11. One end of the injection molding tube 120 away from the vertical plate 15 is fixedly connected to an injection molding machine 122. The injection molding machine 122 is provided with a screw 121 inside. The screw 121 is located inside the injection molding tube 120. See also Figure 5 As shown, the working principle of the screw 121 of the injection molding machine 122 is known to those skilled in the art, that is, the motor or other power device provides power; the motor is connected to the screw 121 through a transmission device (such as a belt drive, a gear drive, etc.), and the rotational power is transmitted to the screw 121, so that the screw 121 rotates in the injection molding tube 120; As the screw 121 rotates continuously, the plastic entering the screw groove will be continuously pushed forward, and in the process of conveying the plastic forward, the screw 121 will also compact the plastic; the gap between the screw 121 and the injection tube 120 is very small, and when the plastic passes through this gap, it will be squeezed, thereby increasing the density of the plastic and making it denser; under the rotation and pushing action of the screw 121, the plastic is continuously sheared, rubbed and heated in the injection tube 120, gradually changing from a solid state to a molten state, completing the plasticization process; when the plastic is completely plasticized, the screw 121, under the action of the thrust of the injection cylinder piston, injects the molten plastic in the storage chamber into the mold 130 through the injection head at high speed and high pressure; during the injection process, the screw 121 will continue to advance forward to fill the entire cavity with the molten plastic until the injection is completed.

[0022] Next, the specific structure of the molding assembly 13 is disclosed. The molding assembly 13 also includes a circulation pump 132. The circulation pump 132 is fixedly connected to the top of the base 1 and located at the bottom of the injection tube 120. Two hoses 131 are fixedly connected between the circulation pump 132 and the mold 130. See also Figure 6As shown, the mold 130 is connected to the circulation pump 132 through two hoses 131, and the cooling liquid inside the mold 130 is circulated by the circulation pump 132 to maintain the cooling temperature inside the mold 130; the working principle of the circulation pump 132 is known to those skilled in the art. When the circulation pump 132 is working, the pump body is first filled with cooling liquid before starting, and after starting, the motor drives the impeller to rotate at high speed, so that the cooling liquid is thrown to the periphery of the impeller by centrifugal force to form a high-pressure area and the center of the impeller to form a low-pressure area. Under the pressure difference between the inlet and the outlet, the cooling liquid is sucked from the inlet and discharged from the outlet after being accelerated and pressurized by the impeller. The motor continues to run to realize the continuous circulation of the cooling liquid in the system, and forms a cooling system with the radiator to take away the heat; Therefore, the coolant in the circulating pump 132 is transported to the inside of the mold 130 through one of the hoses 131, and the circulating liquid in the mold 130 is extracted through another hose 131, so that the coolant circulates back and forth inside the mold 130, so that the mold 130 is always in a low temperature state.

[0023] Finally, the specific structure of the compression molding assembly 14 is disclosed. The compression molding assembly 14 also includes a support plate 140, which is fixedly connected to the top of the base 1 at one end away from the blanking piece 11, and a cylinder 141 is fixedly connected inside the support plate 140; a compression molding head 143 is fixedly connected to the end of the piston rod of the cylinder 141, and guide pillars 142 are provided near the four corners between the support plate 140 and the vertical plate 15, and the compression molding head 143 is movably connected between the outer walls of the four guide pillars 142; See also Figure 7 As shown, the piston rod of the cylinder 141 pushes the compression molding head 143 to move on the top of the base 1, and the compression molding head 143 is die-casted into the mold 130; the cylinder 141 is supported by the support plate 140, and the movement of the compression molding head 143 is provided with stability by the guide column 142.

[0024] The compression molding head 143 includes a fixed plate 1430, which is fixedly connected to the end of the piston rod of the cylinder 141. A pressing plate 1431 is provided between the fixed plate 1430 and the inside of the mold 130, and an elastic member 1432 is fixedly connected between the pressing plate 1431 and the fixed plate 1430. See also Figure 8 As shown, by calculating the required plastic thickness, after the cylinder 141 drives the fixed plate 1430 to move to the corresponding position, the pressing plate 1431 approaches the inside of the mold 130 under the elastic expansion and contraction action of the elastic member 1432, thereby squeezing the plastic inside the mold 130; when the material inside the mold 130 expands under high temperature, its expansion force will push the pressing plate 1431 to approach the fixed plate 1430, so that the elastic member 1432 contracts; when the pressing plate 1431 moves out from the inside of the mold 130, the distance between the pressing plate 1431 and the end of the mold 130 increases; See also Figure 3 and Figure 4 As shown, at this time, the hose 131 between the pressing plate 1431 and the mold 130 expands and contracts, so that the opening of the hose 131 is enlarged, so that the coolant flows faster inside the hose 131, and the circulation speed of the coolant inside the mold 130 is accelerated, so that the mold 130 cools the plastic inside it faster; by accelerating the cooling of the expanded plastic, the expansion force of the plastic is weakened, and the plastic begins to shrink, which facilitates the continuous injection of plastic into the mold 130 and ensures the quality of the plastic after molding; Furthermore, during the injection molding process, the pressing plate 1431 continuously applies extrusion force to the material inside the mold 130 under the action of the elastic member 1432, so that the filling of the plastic melt in the mold cavity of the mold 130 forms a dynamic process; when the melt first enters the mold cavity, air may be drawn in for various reasons to form bubble nuclei; by continuously applying pressure, the melt can be continuously compacted in the mold cavity, just like squeezing a sponge hard to squeeze out the air therein, thereby reducing the existence of bubble nuclei and further reducing the possibility of bubble generation; at the same time, the continuous pressure can keep the melt in a tight state, making the distance between plastic molecules smaller and the arrangement more closely and neatly, so that it is difficult for gas to form stable bubbles therein; The strength and toughness of the plastic product injected in the mold 130 are enhanced, and the dimensional stability is improved, so that the product can withstand greater external forces and has higher dimensional accuracy; at the same time, the scrap rate and production costs can be reduced, waste generation can be reduced, production efficiency can be improved, and waste of raw materials can be avoided.

[0025] Embodiment 2: This embodiment is based on the content provided in Embodiment 1, and aims to provide a method for an overflow-proof plastic injection molding device, and the specific steps are as follows: S1. The injection molding machine 122 drives the screw 121 to rotate continuously in the injection molding tube 120, and the plastic particles entering the screw groove are continuously pushed forward. In this process, the plastic is subjected to shear force and friction force from all directions in the relatively closed space of the injection molding tube 120, and is also constantly absorbing heat. These complex effects are intertwined with each other, causing the physical state of the plastic to gradually change from the initial solid state to the molten state little by little until the entire plasticization process is completed. When the plastic is completely plasticized, the screw 121 is driven by the powerful thrust of the injection cylinder piston to inject the molten plastic stored in the storage chamber into the interior of the mold 130 at a very high speed and pressure. S2, the coolant in the circulation pump 132 is transported to the inside of the mold 130 through one of the hoses 131, so that the coolant shuttles inside the mold 130 to take away the heat; then, the circulating liquid in the mold 130 is extracted through another hose 131; this cycle is repeated, so that the mold 130 can always be kept at a low temperature, providing a stable environment for the injection molding process; S3. After accurately calculating the required plastic thickness, the cylinder 141 drives the fixed plate 1430 to move smoothly to the corresponding position; then, the pressing plate 1431 slowly approaches the inside of the mold 130 under the elastic expansion and contraction of the elastic member 1432, thereby properly squeezing the plastic inside the mold 130; in this process, the support plate 140 stably supports the cylinder 141 to ensure its stability during operation, and the guide column 142 provides a reliable guide for the movement of the compression head 143, making its movement more stable and accurate; S4. When the material inside the mold 130 expands at a high temperature, the strong force generated by the expansion pushes the pressing plate 1431 toward the fixed plate 1430, causing the elastic member 1432 to contract; as the pressing plate 1431 moves outward from the inside of the mold 130, the distance between the pressing plate 1431 and the end of the mold 130 gradually increases; at this time, the hose 131 compressed between the pressing plate 1431 and the mold 130 expands due to the increase in the distance between the pressing plate 1431 and the mold 130, and its opening increases with the expansion, so that the flow speed of the coolant inside the hose 131 is greatly accelerated; this accelerated flow of coolant makes the circulation speed of the coolant inside the mold 130 also accelerate accordingly, so that the mold 130 can cool the plastic inside it faster; through this method of rapid cooling of the plastic, the expansion force of the plastic is effectively weakened, and the expanded plastic begins to shrink; in this way, the plastic can be continuously injected into the mold 130, ensuring the quality of the plastic after molding, so that it better meets the production requirements; S5. When the material inside the mold 130 pushes the pressing plate 1431 in an expanded state, it can not only increase the cooling speed of the mold 130, but also reduce the flow speed of the injection material, thereby effectively alleviating the area occupied by the expansion of the material inside the mold 130; S6. When the material is gradually cooled in the mold 130, the expanded part of the material begins to shrink to leave space inside the mold 130. The pressing plate 1431 rebounds and is pressed inside the mold 130 under the elastic action of the elastic member 1432. This action causes the hose 131 to be clamped between the mold 130 and the pressing plate 1431 again. The cross-sectional area of ​​the hose 131 is reduced, and the circulation speed of the coolant inside the mold 130 is reduced accordingly. The cooling speed of the mold 130 is also reduced accordingly, so as to avoid the material from being completely cooled before the injection molding is complete. S7. During the injection molding process, the material is continuously transported into the mold 130 to ensure a stable supply of material, and the cooling speed is intelligently and adaptively adjusted according to the degree of expansion; and, during the extrusion operation of the mold 130 by the pressing plate 1431, it is ensured that a stable pressure is continuously applied to the material being injected inside the mold 130, and the air originally existing in the mold 130 is effectively squeezed out, which can greatly reduce the generation of bubbles during the injection molding process, enhance the strength and toughness of the product, and improve the dimensional stability of the product, thereby ensuring that the product quality meets high standards.

[0026] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An anti-overflow plastic injection molding device, comprising a base (1), characterized in that: A blanking piece (11) is provided near one end of the top of the base (1), a vertical plate (15) is fixedly connected near the middle of the top of the base (1), an injection molding component (12) is provided between the vertical plate (15) and the blanking piece (11), and a molding component (13) is provided between the outer wall of the vertical plate (15) on a side away from the blanking piece (11) and the top of the base (1); The molding assembly (13) comprises a mold (130), and the mold (130) is fixedly connected to an outer wall of a side of the vertical plate (15) away from the blanking piece (11); a compression molding assembly (14) is provided at one end of the top of the base (1) away from the blanking piece (11), and the compression molding assembly (14) comprises a compression molding head (143), and the compression molding head (143) is movably connected to the inside of the mold (130); The injection molding component (12) is used to extrude the material in the blank (11) into the mold (130); the molding component (13) is used to cool the high-temperature material; the compression molding head (143) is used to extrude the material inside the mold (130); the material inside the mold (130) expands at a high temperature, pushing the compression molding head (143) to contract; the contraction force of the compression molding head (143) increases the cooling speed of the molding component (13).

2. The anti-overflow plastic injection molding device according to claim 1, characterized in that: The injection molding assembly (12) comprises an injection molding tube (120), wherein the injection molding tube (120) is fixedly connected to the inside of the blanking piece (11), and an end of the injection molding tube (120) away from the vertical plate (15) is fixedly connected to an injection molding machine (122), wherein a screw (121) is provided inside the injection molding machine (122), and the screw (121) is located inside the injection molding tube (120).

3. The anti-overflow plastic injection molding device according to claim 1, characterized in that: The molding assembly (13) further comprises a circulation pump (132), wherein the circulation pump (132) is fixedly connected to the top of the base (1) and located at the bottom of the injection tube (120), and two hoses (131) are fixedly connected between the circulation pump (132) and the mold (130).

4. The anti-overflow plastic injection molding device according to claim 1, characterized in that: The compression molding assembly (14) further comprises a support plate (140), wherein the support plate (140) is fixedly connected to an end of the top of the base (1) away from the blanking piece (11), and a cylinder (141) is fixedly connected inside the support plate (140).

5. The anti-overflow plastic injection molding device according to claim 4, characterized in that: A compression head (143) is fixedly connected to the end of the piston rod of the air cylinder (141), guide pillars (142) are provided near four corners between the support plate (140) and the vertical plate (15), and the compression head (143) is movably connected between the outer walls of the four guide pillars (142).

6. The anti-overflow plastic injection molding device according to claim 5, characterized in that: The compression molding head (143) comprises a fixed plate (1430), the fixed plate (1430) being fixedly connected to the end of the piston rod of the cylinder (141), a pressing plate (1431) being provided between the fixed plate (1430) and the inside of the mold (130), and an elastic member (1432) being fixedly connected between the pressing plate (1431) and the fixed plate (1430).

7. A method for operating an anti-overflow plastic injection molding device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1. First, the injection molding component (12) is started to fully mix and stir the material inside the blank (11), and heat it at a high temperature, and the material is pressed into the mold (130) through the injection molding component (12); S2, the compression molding head (143) is pressed into the interior of the mold (130) by means of the expansion and contraction of the compression molding component (14), and when the material inside the mold (130) expands, the compression molding head (143) is driven to contract; S3, when the compression molding head (143) contracts, the cooling speed of the molding component (13) is accelerated, and the expanded material inside the mold (130) is cooled and contracted, so as to prevent the material inside the mold (130) from expanding too fast and causing overflow; S4. When the material inside the mold (130) shrinks due to cooling and the slowing down of the injection molding flow rate, the compression molding head (143) will rebound and continue to press inside the mold (130), thereby increasing the cooling speed and speeding up the injection molding flow rate, making it convenient to continue to press the material into the mold (130), and this reciprocating process ensures the quality of plastic injection molding.

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