A continuous injection mold
By combining the motor-driven threaded rod and the pneumatic telescopic rod, precise demolding and efficient material collection of irregularly shaped plastic shells are achieved, solving the problem of low demolding efficiency in the production of irregularly shaped plastic shells using existing molds, and improving production efficiency and product quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU AMEI PLASTIC CO LTD
- Filing Date
- 2025-05-27
- Publication Date
- 2026-07-21
AI Technical Summary
Existing continuous injection molds lack effective demolding height adjustment structures when dealing with the production of irregularly shaped plastic shells with different heights, thicknesses, or significant differences in demolding difficulty, resulting in low injection molding efficiency.
By setting up the coordinated action of motor, threaded rod, top frame, pneumatic telescopic rod and bevel gear, the demolding height of irregular plastic shells can be precisely controlled, and the efficient and safe collection of plastic shells can be achieved through the cooperation of pneumatic telescopic rod and push plate.
It enables precise demolding and efficient material collection of irregularly shaped plastic shells, improving production efficiency and product quality, and ensuring the stability and reliability of continuous injection molding.
Smart Images
Figure CN224527902U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of mold design technology, and in particular to a continuous injection mold. Background Technology
[0002] Injection molds are tooling devices used for molding and demolding, widely used in modern manufacturing, especially in plastics, rubber, and metal casting. Their main functions include shaping, setting, and assisting demolding. Through precise mold design, they efficiently achieve mass production of complex-shaped workpieces, improving product quality and production efficiency. Announcement No. CN219505361U discloses a continuous injection mold, relating to mold design technology. It includes a mounting plate, an upper mold base, and a lower mold base. The mounting plate is vertically arranged, with the upper and lower mold bases spaced vertically on the mounting plate. The upper mold base is slidably connected to the mounting plate. An upper mold is detachably mounted on the upper mold base. The bottom of the lower mold has a second through hole, and the lower mold base has a third through hole communicating with the second through hole. A transmission block is located inside the second through hole, fitting against the inner wall of the second through hole and being connected to the upper mold base. Its upper end is on the same horizontal line as the bottom end of the second through hole. The mounting plate has a driving assembly for driving the upper mold base and a pushing assembly for pushing the molded workpiece. This invention relates to a device that can perform continuous injection molding operations. Both the upper and lower molds are detachable, allowing for the replacement of different molds for continuous injection molding as needed. However, when producing irregularly shaped plastic shells with varying heights, thicknesses, or significant differences in demolding difficulty, such as small precision plastic parts and large outer shells, the lack of a demolding height adjustment structure makes it impossible to adapt to the demolding requirements of different product specifications, thus affecting the efficiency of the injection molding process. Therefore, improvements are needed. Utility Model Content
[0003] The purpose of this utility model is to provide a continuous injection mold that can at least solve the problems of the prior art mentioned above.
[0004] To achieve the above objectives, this utility model provides a continuous injection mold, including a base, a mold holder fixedly mounted on the surface of the base, a mold groove formed on the surface of the mold holder, an ejection groove formed on the surface of the mold holder, a demolding groove formed on the surface of the base, a motor fixedly mounted on the surface of the base, a connecting rod fixedly mounted on the output end of the motor, a bevel gear A fixedly mounted on the other end of the connecting rod, a bevel gear B meshing on the surface of bevel gear A, a threaded rod fixedly mounted on the surface of bevel gear B, a limit block fixedly mounted on the other end of the threaded rod, a top bracket threadedly connected to the surface of the threaded rod, a demolding base fixedly mounted on the surface of the demolding groove, a sliding rod fixedly mounted on the surface of the demolding base, a sliding groove and a telescopic rod groove formed on the surface of the top bracket, a pneumatic telescopic rod A fixedly mounted on the surface of the telescopic rod groove, a top plate fixedly mounted on the output end of the pneumatic telescopic rod A, and an ejection structure fixedly mounted on the surface of the top plate.
[0005] Optionally, the ejection structure includes a top post, a spring groove, a spring, and a top cap. The surface of the top post has a spring groove, and a spring is fixedly installed on the surface of the spring groove. The other end of the spring is fixedly installed with a top cap. Here, during the ejection process, the spring can buffer the impact force at the moment of contact between the top post and the plastic shell, avoiding scratches, indentations, or damage to the surface of the irregularly shaped plastic shell caused by rigid contact. This is especially suitable for thin-walled, high-precision products. Under the action of the spring, the top cap can adaptively conform to the irregular surface of the plastic shell, ensuring that the ejection force is evenly distributed and preventing excessive local force from causing product deformation.
[0006] Optionally, the threaded rod is a bidirectional threaded rod, and there are two slide rods symmetrically distributed on both sides of the threaded rod. The surface of the slide rod is slidably connected to the surface of the slide groove. Here, the bidirectional threaded rod and the symmetrical double slide rods cooperate to enable the top frame to move synchronously and symmetrically on both sides, with uniform force distribution, avoiding tilting and swaying. The guiding effect of the slide rods and slide grooves further ensures the smooth lifting of the top frame, ensuring that the pneumatic telescopic rod A vertically ejects the material, protecting the product from damage. The bidirectional threaded synchronous adjustment, combined with the slide rods to reduce deviation, can accurately control the height of the top frame and achieve precise control of the material ejection height.
[0007] Optionally, there are two telescopic rod slots and two pneumatic telescopic rods A symmetrically distributed on both sides of the top frame. The side of the top plate is slidably connected to the surface of the ejector groove. Here, the telescopic rod slots and the pneumatic telescopic rods A are symmetrically distributed on both sides of the top frame. Combined with the slidable connection between the side of the top plate and the ejector groove, the top plate can be subjected to uniform force, ensuring that the irregularly shaped plastic shell does not deform or crack during demolding. The slidable connection provides stable guidance for the top plate, avoiding deviation and shaking, and ensuring smooth demolding. The simultaneous operation of the two rods improves demolding efficiency. The symmetrical structure has strong versatility and can be adapted to different plastic shells to meet diverse production needs.
[0008] Optionally, a receiving rack is fixedly installed on the side of the base, and a receiving box is placed on the surface of the receiving rack. A connecting block is fixedly installed on the side of the mold base, and a pneumatic telescopic rod B is fixedly installed inside the connecting block. A push plate is fixedly installed at the output end of the pneumatic telescopic rod B, and a rubber plate is fixedly installed on the surface of the push plate. A slide rail is fixedly installed on the surface of the mold base. Here, the receiving rack and receiving box on the side of the base facilitate the centralized collection of the demolded plastic shells. The pneumatic telescopic rod B on the side of the mold base connects to the push plate with the rubber plate, which can automatically and smoothly push the plastic shells to the receiving box to avoid damaging the products. The slide rail on the mold base provides guidance for the plastic shells, ensuring the linear movement of the push plate, improving the stability and accuracy of receiving, and increasing production efficiency.
[0009] Optionally, the bottom surface of the pusher plate is in contact with the surface of the mold base, and the receiving surface of the receiving box is in contact with the discharge surface of the mold base, with the contact point being sloping. This ensures that the pusher plate moves with precise and stable direction, avoiding deviation, and can accurately push the plastic shell to the target position. The receiving surface of the receiving box is in contact with the discharge surface of the mold base and is sloping. On the one hand, it allows the plastic shell to slide smoothly into the receiving box along the slope with its own weight, improving the receiving efficiency. On the other hand, it can prevent the plastic shell from being damaged by collision due to excessive drop during the transfer process. At the same time, the sloping design also facilitates the neat stacking of the plastic shell in the receiving box, improving the smoothness and efficiency of the overall production process.
[0010] The above-mentioned technical solutions in a continuous injection mold provided by this utility model embodiment have at least one of the following technical effects:
[0011] 1. In this utility model, by setting up a motor, a threaded rod, a top frame, a pneumatic telescopic rod A, and a bevel gear B, the synergistic effect of these structures can achieve precise control of the demolding height of irregularly shaped plastic shells. After the motor starts, it drives the connecting rod and bevel gear A to rotate, and bevel gear B, which meshes with bevel gear A, rotates accordingly, thereby causing the threaded rod to rotate. Due to the characteristics of the bidirectional thread, the top frame can be driven to rise and fall smoothly along the slide rod. By controlling the forward and reverse rotation and the number of rotations of the motor, the height of the top frame can be precisely adjusted. After the height of the top frame is determined, the pneumatic telescopic rod A extends from the corresponding height to eject the material. This process can be flexibly adjusted according to the demolding requirements of different plastic shells, effectively avoiding over-ejection or under-ejection, improving demolding quality and efficiency, and ensuring the stability and reliability of continuous injection molding.
[0012] 2. In this utility model, by setting up a receiving box, pneumatic telescopic rod B, push plate, rubber plate, and slide rail, the synergistic effect of these structures is used to achieve efficient and safe material collection after the plastic shell is demolded. After the pneumatic telescopic rod B is activated, it drives the connected push plate to slide smoothly along the slide rail. The bottom surface of the push plate is in contact with the surface of the mold base to ensure accurate pushing direction and avoid deviation. The rubber plate on the surface of the push plate can prevent scratching and damage to the product surface when it comes into contact with the plastic shell. At the same time, the receiving surface of the receiving box is in contact with the discharge surface of the mold base and is sloped. After the push plate pushes the plastic shell to the contact point, the plastic shell can slide smoothly into the receiving box along the slope, automatically completing the material transfer and collection, reducing manual intervention, and improving production efficiency and product qualification rate. Attached Figure Description
[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 A schematic diagram of a continuous injection mold is provided for this utility model;
[0015] Figure 2 This utility model provides a schematic diagram of the demolding structure of a continuous injection mold;
[0016] Figure 3 This utility model provides a schematic diagram of an adjustable spacing structure for a continuous injection mold;
[0017] Figure 4 An exploded view of the demolding structure of a continuous injection mold is provided for this utility model;
[0018] Figure 5 This utility model provides a schematic diagram of the ejection structure of a continuous injection mold;
[0019] Figure 6 This utility model presents a schematic diagram of a material receiving structure for a continuous injection mold.
[0020] The following are the labeling elements in the figure:
[0021] 1—Base 2—Mold base 3—Mold groove
[0022] 4—Motor 5—Demolding groove 6—Ejection groove
[0023] 7—Connecting rod; 8—Bevel gear A; 9—Bevel gear B
[0024] 10—Threaded rod 11—Limit block 12—Top frame
[0025] 13—Demolding base; 14—Slide bar; 15—Slide groove
[0026] 16—Telescopic rod slot; 17—Pneumatic telescopic rod A; 18—Top plate
[0027] 19—Top column; 20—Spring groove; 21—Spring
[0028] 22—Top cap 23—Receiving rack 24—Receiving box
[0029] 25—Connecting block; 26—Pneumatic telescopic rod B; 27—Push plate
[0030] 28—Plastic sheet 29—Slide rail. Detailed Implementation
[0031] The embodiments of this utility model are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The following description is based on the accompanying drawings. Figure 1-6 The described embodiments are exemplary and intended to explain embodiments of the present invention, and should not be construed as limiting the present invention.
[0032] In the description of the embodiments of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0034] In this embodiment of the invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention according to the specific circumstances.
[0035] Example 1
[0036] Please see Figure 1-5This utility model provides a technical solution: a continuous injection mold, including a base 1, which serves as the basic support component of the entire mold, providing a stable mounting platform for other components of the mold, ensuring the mold remains stable during operation, reducing vibration and shaking, and ensuring the stability and accuracy of the demolding process. A mold base 2 is fixedly mounted on the surface of the base 1, and its surface has a mold groove 3 for forming irregularly shaped plastic shells, providing specific space and shape for the injection molding of the plastic shells. An ejection groove 6 provides a channel for the ejection action of the ejector plate 18, ensuring that the plastic shell can be demolded smoothly. The surface of the mold base 2 has a mold groove 3, the surface of the mold base 2 has an ejection groove 6, the surface of the base 1 has a demolding groove 5, and the surface of the base 1 is fixedly mounted with a mold base 2. Motor 4 provides power to the entire demolding system. The rotation of motor 4 drives the connecting rod 7 and bevel gear A8 to rotate, thereby transmitting power to subsequent transmission components. The output end of motor 4 is fixedly mounted with the connecting rod 7, and the other end of the connecting rod 7 is fixedly mounted with the bevel gear A8. A bevel gear B9 meshes with the surface of bevel gear A8, and a threaded rod 10 is fixedly mounted on the surface of bevel gear B9. A limit block 11 is fixedly mounted on the other end of the threaded rod 10, and a top bracket 12 is threadedly connected to the surface of the threaded rod 10. A demolding base 13 is fixedly mounted on the surface of the demolding groove 5, and a sliding rod 14 is fixedly mounted on the surface of the demolding base 13. The threaded rod 10 is a bidirectional threaded rod, and there are two sliding rods 14 symmetrically distributed on both sides of the threaded rod 10. The surface of the top frame 12 is slidably connected to the surface of the slide groove 15. Here, the bidirectional threaded rod cooperates with the symmetrical double slide rod 14 to enable the top frame 12 to move synchronously and symmetrically on both sides, with uniform force distribution, avoiding tilting and swaying. The guiding effect of the slide rod 14 and the slide groove 15 further ensures the smooth lifting and lowering of the top frame 12, ensuring that the pneumatic telescopic rod A17 ejects the material vertically, protecting the product from damage. The bidirectional threaded synchronous adjustment, combined with the slide rod 14 to reduce deviation, can accurately control the height of the top frame 12, achieving precise control of the material ejection height. The surface of the top frame 12 is provided with a slide groove 15 and a telescopic rod groove 16. The pneumatic telescopic rod A17 is fixedly installed on the surface of the telescopic rod groove 16. The output end of the pneumatic telescopic rod A17 is fixedly installed with a top plate 18. The telescopic rod groove 16 and the pneumatic telescopic rod A17 are connected. Two 7 are symmetrically distributed on both sides of the top frame 12. The side of the top plate 18 is slidably connected to the surface of the ejector groove 6. Here, the telescopic rod groove 16 and the pneumatic telescopic rod A17 are symmetrically distributed on both sides of the top frame 12. With the sliding connection between the side of the top plate 18 and the ejector groove 6, the top plate 18 can be evenly stressed, ensuring that the irregular plastic shell does not deform or crack during demolding. The sliding connection provides stable guidance for the top plate 18, avoiding deviation and shaking, and ensuring smooth demolding. The simultaneous operation of the two rods improves demolding efficiency. The symmetrical structure has strong versatility and can be adapted to different plastic shells to meet diverse production needs. The ejector structure is fixedly installed on the surface of the top plate 18. The ejector structure includes an ejector post 19, a spring groove 20, a spring 21, and an ejector cap 22. The surface of the ejector post 19 has a spring groove 20.A spring 21 is fixedly installed on the surface of the spring groove 20, and a top cap 22 is fixedly installed on the other end of the spring 21. Here, during the ejection process, the spring 21 can buffer the impact force of the ejector pin 19 contacting the plastic shell at the moment of contact, avoiding scratches, indentations or damage to the surface of the irregular plastic shell caused by rigid contact. It is especially suitable for thin-walled, high-precision products. Under the action of the spring 21, the top cap 22 can adaptively conform to the irregular surface of the plastic shell, ensuring that the ejection force is evenly distributed and preventing excessive local force from causing product deformation. Based on the base 1 and the mold base 2, the double-threaded rod is driven by the motor 4 through the bevel gear transmission. With the help of the symmetrical double slide rods 14, the ejector frame 12 can be raised and lowered smoothly. The ejection height of the pneumatic telescopic rod A17 is precisely controlled. The double pneumatic telescopic rods A17 are symmetrically arranged on the ejector frame 12. Together with the top plate 18 and the ejection structure with spring 21 buffer, it ensures that the plastic shell is subjected to uniform force and demolds smoothly, ensuring the reliability and stability of continuous injection molding.
[0037] Example 2
[0038] Please see Figure 6A receiving rack 23 is fixedly installed on the side of the base 1 to support the receiving box 24. This rationally planned receiving space provides a fixed storage location for the demolded plastic shells, keeping the production site neat and orderly, facilitating centralized management and material handling. The receiving box 24 is placed on the surface of the receiving rack 23. Its receiving surface is flush with the discharge surface of the mold base 2 and is sloped. This sloped design allows the plastic shells to slide automatically into the box under gravity after being pushed by the pusher plate 27, reducing manual intervention. It also prevents damage from collisions due to excessive drop and facilitates neat stacking of the plastic shells inside the box, improving storage efficiency. A connecting block 2 is fixedly installed on the side of the mold base 2. 5. A pneumatic telescopic rod B26 is fixedly installed inside the connecting block 25. Its telescopic movement provides power to the push plate 27, allowing precise control of the push plate 27's stroke and thrust. This enables automatic transfer of the plastic shell from the mold base 2 to the receiving box 24, improving production efficiency and automation. The output end of the pneumatic telescopic rod B26 is fixedly installed with the push plate 27, and a rubber plate 28 is fixedly installed on the surface of the push plate 27. A slide rail 29 is fixedly installed on the surface of the mold base 2. Here, a receiving rack 23 and a receiving box 24 are provided on the side of the base 1 for convenient centralized collection of the demolded plastic shells. The pneumatic telescopic rod B26 on the side of the mold base 2 connects to the push plate 27 with the rubber plate 28, automatically and smoothly pushing the plastic shell to the receiving box 24. To avoid damaging the product, the slide rail 29 on the mold base 2 provides guidance for the plastic shell, ensuring the linear movement of the push plate 27, improving the stability and accuracy of material collection, and increasing production efficiency. The bottom surface of the push plate 27 is in contact with the surface of the mold base 2, and the receiving surface of the receiving box 24 is in contact with the discharge surface of the mold base 2, with the contact point being sloping. Here, it is ensured that the push plate 27 moves with precise and stable direction, avoiding deviation, and can accurately push the plastic shell to the target position. The receiving surface of the receiving box 24 is in contact with the discharge surface of the mold base 2 and is sloping. On the one hand, it allows the plastic shell to slide smoothly into the receiving box 24 along the slope with its own weight, improving material collection efficiency. On the other hand, it prevents the plastic shell from being damaged by drop during the transfer process. Excessive size can lead to collision damage, while the sloping design facilitates the neat stacking of plastic shells within the receiving box 24, improving the overall smoothness and efficiency of the production process. The coordinated action of various components enhances production efficiency and product quality. The base 1 is equipped with a receiving rack 23 and a receiving box 24, standardizing material storage and optimizing the production layout. The pneumatic telescopic rod B26 drives the push plate 27 with the rubber plate 28, realizing automated and flexible transfer of plastic shells and avoiding surface damage. The slide rail 29 ensures precise and stable pushing. The sloping structure between the receiving box 24 and the mold base 2 utilizes gravity to allow materials to slide into the box, reducing collision damage, facilitating stacking and storage, improving material collection efficiency, ensuring product integrity, and optimizing the smoothness and efficiency of the production process.
[0039] Working principle: When dealing with irregularly shaped plastic shells of varying heights, thicknesses, or demolding difficulties, and needing to adjust the demolding height to ensure the efficiency of continuous injection molding, motor 4 is started. Motor 4 drives bevel gear A8 to rotate, bevel gear B9 causes threaded rod 10 to rotate, and the rotation of threaded rod 10 drives the ejector frame 12 to move synchronously, achieving smooth lifting and lowering of the ejector frame 12, thereby precisely adjusting the height of the ejector frame 12. After the ejector frame 12 is adjusted to the appropriate height, the two symmetrically distributed pneumatic telescopic rods A17 are activated. The top plate 18 is pushed to slide along the ejection groove 6. The ejection structure on the top plate 18 contacts the plastic shell. The spring 21 buffers the impact force at the moment of contact. The top cap 22 fits against the surface of the plastic shell and ejects the plastic shell from the mold groove 3. After ejection, the pneumatic telescopic rod B26 is activated, which drives the push plate 27 to slide along the slide rail 29. The rubber plate 28 contacts the plastic shell and pushes it into the receiving box 24. The inclined design of the receiving box 24, which fits against the discharge surface of the mold base 2, allows the plastic shell to slide into the receiving box 24 by gravity to complete the receiving.
[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A continuous injection mold, comprising a base (1), characterized in that: A mold base (2) is fixedly mounted on the surface of the base (1). A mold groove (3) is formed on the surface of the mold base (2). An ejection groove (6) is formed on the surface of the mold base (2). A demolding groove (5) is formed on the surface of the base (1). A motor (4) is fixedly mounted on the surface of the base (1). A connecting rod (7) is fixedly mounted on the output end of the motor (4). A bevel gear A (8) is fixedly mounted on the other end of the connecting rod (7). A bevel gear B (9) meshes with the surface of the bevel gear A (8). A threaded rod (10) is fixedly mounted on the surface of the bevel gear B (9). (10) has a limit block (11) fixedly installed at the other end. The threaded rod (10) has a top frame (12) threadedly connected to its surface. The demolding groove (5) has a demolding base (13) fixedly installed on its surface. The demolding base (13) has a slide rod (14) fixedly installed on its surface. The top frame (12) has a slide groove (15) and a telescopic rod groove (16) opened on its surface. The telescopic rod groove (16) has a pneumatic telescopic rod A (17) fixedly installed on its surface. The output end of the pneumatic telescopic rod A (17) has a top plate (18) fixedly installed on its surface. The top plate (18) has an ejection structure fixedly installed on its surface.
2. The continuous injection mold according to claim 1, characterized in that: The ejection structure includes a top post (19), a spring groove (20), a spring (21), and a top cap (22). The surface of the top post (19) is provided with a spring groove (20), and a spring (21) is fixedly installed on the surface of the spring groove (20). The other end of the spring (21) is fixedly installed with a top cap (22).
3. The continuous injection mold according to claim 1, characterized in that: The threaded rod (10) is a bidirectional threaded rod, and there are two slide rods (14) symmetrically distributed on both sides of the threaded rod (10). The surface of the slide rod (14) is slidably connected to the surface of the groove (15).
4. The continuous injection mold according to claim 1, characterized in that: There are two telescopic rod slots (16) and pneumatic telescopic rods A (17) symmetrically distributed on both sides of the top frame (12), and the side of the top plate (18) is slidably connected to the surface of the ejector slot (6).
5. The continuous injection mold according to claim 1, characterized in that: A receiving rack (23) is fixedly installed on the side of the base (1), and a receiving box (24) is placed on the surface of the receiving rack (23). A connecting block (25) is fixedly installed on the side of the mold base (2). A pneumatic telescopic rod B (26) is fixedly installed inside the connecting block (25). A push plate (27) is fixedly installed at the output end of the pneumatic telescopic rod B (26). A rubber plate (28) is fixedly installed on the surface of the push plate (27). A slide rail (29) is fixedly installed on the surface of the mold base (2).
6. The continuous injection mold according to claim 5, characterized in that: The bottom surface of the push plate (27) is in contact with the surface of the mold base (2), and the receiving surface of the receiving box (24) is in contact with the discharge surface of the mold base (2) with the contact area being sloping.