Thick Parts Injection Mold and Operation Method

Abstract

The present application belongs to the field of plastic processing technology, and specifically relates to an injection mold and an operating method. Disclosed is an injection mold for thick parts, comprising: a cavity, one of the side walls of the cavity being a movable push block, which can change the volume of the cavity by moving the push block, a push rod, one end of which is connected to the push block and is located outside the cavity, an ejector plate, which is connected to the other end of the push rod, and a buffer structure and / or a cavity compression structure. The design of the push block, the push rod, the ejector plate, the buffer structure and / or the cavity compression structure can significantly reduce the delamination and pore defects of thick plastic parts during the cooling process, and provide a reliable technical solution for the processing of thick parts made of plastic instead of aluminum.

Description

Technical Field

[0001] The present application belongs to the field of plastic processing technology, and specifically relates to an injection mold and an operating method. Background Art

[0002] Plastics are gradually replacing traditional metal structural parts due to their advantages such as light weight, low raw material cost, low processing cost, easy molding, and high production efficiency. However, an important factor that needs to be considered in the replacement process is the mechanical properties of the plastic structure. Due to the limitations of the characteristics of the plastic material itself, there are many reasons that will reduce the mechanical properties of the product, but during the processing and cooling process, the internal structure of the part will shrink due to defects such as stratification and pores. Especially for thicker parts, the defects are particularly obvious, resulting in a deterioration in the appearance of the plastic part and a decrease in mechanical properties. It is difficult to meet the requirements of the original metal structural parts, which has been a pain point that the industry has been unable to solve.

[0003] Due to the particularity of plastic materials during processing, the production of plastic samples becomes more difficult as their thickness increases. The thicker the part, the more difficult it is to control shrinkage and deformation, and defects such as delamination and pores are difficult to solve. The thickness of the parts in the prior art is usually below 7mm, and those above 7mm are thick parts, which are difficult to achieve with conventional technology. 3D printing technology can directly print thicker parts. However, due to the mechanical properties of special plastic materials, it is impossible to add high-content reinforcing fillers (such as glass fiber). Its fluidity, rapid cooling and molding properties cannot be realized by 3D printing. In addition, due to the material nozzle structure and process settings during the printing process, defects such as delamination and pores are very likely to occur between different printing layers. The two-color injection molding process can increase the thickness of the part, but two-color injection molding will produce obvious delamination, poor mechanical properties, and easily lead to delamination during the milling process. The compression molding process has high requirements for the thickness of the product. When the thickness is thick, it is easy to cause the sample to shrink and deform quickly, and compression molding is difficult to form small parts. For materials with poor fluidity (such as a high proportion of reinforcing fillers), samples prepared by the compression molding process are very likely to have stratification and pores inside the sample due to exhaust problems.

[0004] In addition, for thick plastic parts with high mechanical property requirements, it is also possible to first prepare a plastic sample that meets the thickness requirements of the part, and then mill out the required sample. However, during the processing and cooling process, there will be defects such as delamination and pores in the internal structure of the part due to shrinkage. Summary of the invention

[0005] In view of the delamination and pore problems caused by thick workpiece processing in the prior art, the present application provides an injection mold that reduces the delamination and pore problems caused by thick workpiece processing. This is specifically achieved through the following technical solutions:

[0006] A thick part injection mold, comprising:

[0007] A cavity, one of the side walls of the cavity is a movable push block, and the volume of the cavity can be changed by moving the push block.

[0008] A push rod, one end of which is connected to the push block and is located outside the cavity.

[0009] An ejector plate connected to the other end of the push rod,

[0010] Buffer structure and / or cavity compression structure,

[0011] The distance between the initial working position of the buffer structure and the ejector plate is ≥ 0. When the distance between the ejector plate and the buffer structure is 0, they are in contact. The buffer structure can drive the ejector plate to move when the push block moves toward the push rod. The buffer structure can apply a buffer thrust to the ejector plate in the opposite direction of the movement of the ejector plate, so that the push block has a buffer resistance in the process of moving toward the push rod.

[0012] The distance between the initial working position of the cavity compression structure and the ejector plate is ≥ 0. When the distance between the ejector plate and the cavity compression structure is 0, they are in a contact state. The cavity compression structure can apply a thrust to the ejector plate in the opposite direction of the movement of the ejector plate by contacting the ejector plate, so that the push block moves toward the inside of the cavity.

[0013] In one embodiment, the buffer structure is one or more elastic elements, and the elastic elements are in a pre-stressed state when working. In the pre-stressed state, the elastic element will give a reverse elastic force to the component that compresses the elastic element, thereby forming a resistance to the movement process, but it is controlled not to completely hinder the movement of the cavity and affect the injection molding process. The elastic element is preferred.

[0014] In one embodiment, the buffer structure is one or more first pressure transmission devices. By controlling the operation of the first pressure transmission device (such as the extension and contraction of the oil cylinder), resistance to the movement process is formed.

[0015] In one embodiment, the buffer structure is one or more elastic elements and one or more first pressure transmission devices, the elastic element is in a pre-stressed state when working, the first pressure transmission device can apply a thrust or a pull to the ejector plate, and the thrust or the pull can apply a buffer thrust to the ejector plate in the opposite direction of the movement of the ejector plate, so that the push block has a buffer resistance in the process of moving toward the push rod; one of the elastic element and the first pressure transmission device is in contact with the ejector plate, and the two are in a series superposition state, or the elastic element and the first pressure transmission device are both in contact with the ejector plate, and the two are in a parallel state. The series superposition state and the parallel state are two different installation methods, which can be selected according to needs. For example, when the compression amount of a single elastic element and the stroke of the oil cylinder are less than required, series connection can be selected to enhance the maximum stroke that provides resistance.

[0016] In one embodiment, the elastic element is one or more of a compression spring, a disc spring, and a nitrogen spring.

[0017] In one embodiment, a guide structure is provided inside the compression spring, which is helpful for controlling the deflection direction of the compression spring when it is working.

[0018] In one embodiment, the guide structure is a guide rod or a shock absorber. The compression spring and the shock absorber can form a damping spring.

[0019] In one embodiment, the cavity compression structure is one or more second pressure transmission devices.

[0020] In one embodiment, the initial position of the cavity compression structure has no direct contact with the ejector plate.

[0021] In one embodiment, the initial position of the cavity compression structure is in direct contact with the ejector plate. If the oil cylinder is fixed to the ejector plate, the installation method of the oil cylinder top and bottom plate can also be realized.

[0022] In one embodiment, the cavity compression structure is composed of one or more second pressure transmission devices and a pressure transmission structure, and the pressure transmission structure is driven by the second pressure transmission device, and is connected with the ejector plate through contact, so as to apply a thrust to the ejector plate in the opposite direction of the movement of the ejector plate, so that the push block moves toward the inside of the cavity.

[0023] In one embodiment, the pressure transmission structure is a seesaw transmission structure or an inclined shovel transmission structure.

[0024] In one embodiment, the first pressure transmission device or the second pressure transmission device is a hydraulic device, a pneumatic device or a gas-liquid mixed pressure device, and can be a hydraulic cylinder, a gas cylinder or a gas-liquid booster cylinder, etc., as required.

[0025] In one of the embodiments, a heating device is provided outside the cavity to prevent the cavity temperature from being too low, which may cause stratification due to cavity temperature differences during the movement of the push plate.

[0026] The present application also provides an operating method of the thick workpiece injection mold described in the aforementioned technical solution, corresponding to the buffer structure and / or the cavity compression structure, including the buffer structure working steps and / or the cavity compression structure working steps:

[0027] The buffer structure has the following working steps: when the cavity is filled with melt, during part or all of the process in which the push block moves toward the push rod, the buffer structure applies a buffer thrust to the ejector plate in the opposite direction of the ejector plate, and transmits the buffer thrust to the push block via the push rod, so that the push block has a buffer resistance in the process of moving toward the push rod;

[0028] The working steps of the cavity compression structure: when the cavity filling melt process is completed, the cavity compression structure applies a thrust or a pull force to the ejector plate, which is transmitted to the push block via the push rod, and pushes the push block to move toward the inside of the cavity. Preferably, the buffer structure and the cavity compression structure exist at the same time, and the two steps are implemented together to further control the compression amount of the melt in the cavity and reduce the stratification and pore defects in the cooling process.

[0029] When the buffer structure and the cavity compression structure exist at the same time, the above working steps are executed in the corresponding order. During the working step of the cavity compression structure, the buffer structure (including the elastic element) is in a compressed state. When the cavity compression structure is working, the buffer structure also provides a thrust to the push block in the same direction as the cavity compression structure to restore the elastic deformation process.

[0030] In one embodiment, the working steps of the cavity compression structure further include a gate cooling process, which is performed after the cavity filling melt process is completed and before the cavity compression structure works. A nozzle or a needle valve hot runner is used to fill the melt into the cavity. When a gate is used, the melt in the nozzle needs to be cooled to prevent overflow from occurring at the nozzle or the melt from being extruded into the injection molding machine when the cavity compression structure works.

[0031] Compared with the prior art, the present application sets one of the side walls of the cavity as a movable push block to control the volume of the cavity, and adjusts the original fixed cavity of the injection mold to a volume-variable cavity, which is also a necessary condition for cooperating with the buffer structure and / or the cavity compression structure; the structural design of the push rod and the ejector plate is used to transmit the force of the ejector plate to the push block through the push rod, avoiding the buffer structure and the cavity compression structure being set inside the mold base (A plate or B plate), which has the following problems: 1) It will make it difficult to monitor the working status of this part of the structure, and the maintenance and replacement of accessories are complicated; 2) When the buffer structure and the cavity compression structure need to provide a larger thrust on the push plate, due to the limitation of the design thickness of the push plate, it is easy to cause the push plate to deform, affecting the cooperation between the push plate and the inner wall of the cavity, and the service life will be greatly shortened; 3) The buffer structure and the cavity compression structure are designed in the mold base, which is limited by the thickness of the mold base and the height size of the cavity. The selected buffer structure and cavity compression structure are short in size and stroke, which is difficult to meet the injection molding requirements of thicker parts. In this solution, the ejector plate is arranged outside the mold base, and the required thickness can be designed and adjusted according to the pressure requirements to avoid deformation caused by excessive pressure. The ejector plate can also be provided with an ejector plate support column to strictly limit the moving direction of the ejector plate to avoid deformation of the push plate due to uneven force on the ejector plate, thereby extending the service life of the mold.

[0032] The technical solution of the present application, including the simultaneous existence of a buffer structure and a cavity compression structure or the selection of one of the two, utilizes extrusion of the melt to further remove the gas between the melts, and increases the melt density, thereby reducing the relatively loose space required for the stratification and pores to appear during the cooling process, thereby extruding the stratification and pores. In addition, when the melt density increases, the melt at the pre-formed stratification and pores needs to be moved elsewhere to form stratification and pores during cooling. The increased density hinders the movement of the melt, thereby reducing the formation of stratification and pores. The present application selects a buffer structure, which can extrude the melt during the process of filling the cavity with melt by the combined action of injection pressure and the buffer structure; the cavity compression structure is selected, which can extrude the melt by squeezing the push block into the cavity after the process of filling the cavity with melt, and the cavity compression structure is an active compression structure, which controls the compression ratio of the melt in the cavity by controlling the compression distance (such as the ejection distance of the ejector plate of the oil cylinder). For the same material, it can be adjusted to the optimal compression ratio based on experiments of multiple parts. Preferably, the buffer structure and the cavity compression structure exist at the same time, which has a better effect, further compresses the melt, and increases the melt density. When the buffer structure exists, the cavity compression structure can be pre-contacted with the ejector plate and supported by the buffer structure, thereby shortening the working time of the cavity compression structure and extending its service life.

[0033] The technical problems of delamination and pores caused by the processing of thick parts to be solved by this application, and the sample requirements of thick parts in the prior art, when the technical personnel in this field use plastic materials instead, in terms of structural design, they will generally choose to avoid the structural design of thick parts, such as using stealing material structural design or gas-assisted molding process to control wall thickness, prevent defects caused by uneven shrinkage, and enhance its mechanical properties by designing reinforcing ribs to meet the needs; other ways to avoid delamination and pores are to adjust the process parameters and structures such as mold temperature and pressure, and no solution to the problem from the perspective of the thick parts themselves has been found. Therefore, the direction of the technical solution of this application to solve the technical problem is not the conventional choice of those skilled in the art. Furthermore, the core components of the mold involved in solving this problem are not a simple combination of structures in the prior art, and require creative design (that is, overcoming the prejudice of the prior art: by controlling the wall thickness) and easy combination in practice.

[0034] The above technical solution of the present application is particularly suitable for products (including sample blocks) with a required sample thickness of ≥10mm. For products with a smaller sample thickness, the probability of delamination and pores is relatively small, except for the case where the mechanical properties of the product are required to be high, or when the sample is milled out of the sample block, delamination and pores are likely to appear on the sample surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the disassembled structure of the thick workpiece mold described in Example 1;

[0036] Figure 2 for Figure 1 A schematic diagram of the structure of the related push block control components;

[0037] Figure 3 It is a schematic diagram of the structure of the relevant push block control component in Example 2;

[0038] Figure 4 It is a schematic diagram of the structure of the related push block control component in Example 3;

[0039] Figure 5 It is a structural schematic diagram of the relevant push block control components in Example 4;

[0040] Figure 6 It is a schematic diagram of the structure of the relevant push block control component in Example 5;

[0041] Figure 7 Cross-sectional photograph of the sample prepared in the comparative example;

[0042] Figure 8 This is a cross-sectional photograph of the sample prepared in Example 5.

[0043] in, Figure 1Some installation components, connecting components, etc. well known to those skilled in the art are omitted, and another mold foot is hidden for easy observation.

[0044] The reference numerals in the figure are: 1 bottom plate, 2 compression spring, 201 push plate guide column, 202 limit block, 3 oil cylinder, 301 shovel piece, 302 inclined block, 303 fixed shaft assembly, 304 rocker assembly, 4 ejector plate, 5 push rod, 6 push block, 7 mold foot, 8 pad, 9 water channel, 10B plate, 1001 cavity, 11A plate, 12 nozzle, 13 panel. DETAILED DESCRIPTION

[0045] The technical solution of the present application is further described below in conjunction with specific embodiments. It should be pointed out that the following description is not intended to limit the claims of the present application.

[0046] A thick part injection mold, comprising:

[0047] A cavity, one of the side walls of the cavity is a movable push block, and the volume of the cavity can be changed by moving the push block.

[0048] A push rod, one end of which is connected to the push block and is located outside the cavity.

[0049] An ejector plate connected to the other end of the push rod,

[0050] Buffer structure and / or cavity compression structure,

[0051] The distance between the initial working position of the buffer structure and the ejector plate is ≥ 0. When the distance between the ejector plate and the buffer structure is 0, they are in contact. The buffer structure can drive the ejector plate to move when the push block moves toward the push rod. The buffer structure can apply a buffer thrust to the ejector plate in the opposite direction of the movement of the ejector plate, so that the push block has a buffer resistance in the process of moving toward the push rod.

[0052] The distance between the initial working position of the cavity compression structure and the ejector plate is ≥ 0. When the distance between the ejector plate and the cavity compression structure is 0, they are in a contact state. The cavity compression structure can apply a thrust to the ejector plate in the opposite direction of the movement of the ejector plate by contacting the ejector plate, so that the push block moves toward the inside of the cavity.

[0053] The above technical solution of the present application omits the selection of other components of the injection mold well known to those skilled in the art, such as a base, an injection port (a nozzle or a needle valve structure), a pressure holding structure, etc.; the cavity may be, but is not limited to, a combination of an A plate (a fixed mold seat) and a B plate (a movable mold seat), and is also called an upper mold seat and a lower mold seat, wherein the upper and lower are only one embodiment, and may also be placed horizontally; the cavity may be a regular cube or cylinder, such as a cavity of a thick sample block, or may be an irregular structure, wherein one direction requires a thicker wall thickness, and then "one of the side walls" preferably corresponds to the thick wall; the push block may be in the shape of a flat plate, or may be in the shape of an arc or other complex structures; one end of the push rod is connected to the push block, and may be a fixed connection, or a non-contact connection, or any other method that can support and enable the push block to move along the cavity, or may be connected by adding a spacer or other structure in the middle, and the connection method between the push rod and the ejector plate is not limited, as long as the ejector plate controls the movement of the push rod, and preferably a fixed connection;

[0054] The buffer structure and / or cavity compression structure includes three technical solutions, all of which can reduce the delamination and porosity problems caused by the processing of thick parts. The distance between the initial working position of the buffer structure and the ejector plate is ≥0, including that the buffer structure directly contacts the ejector plate and does not contact the ejector plate at the beginning. After the ejector plate moves a short distance (such as 2mm, because the workpiece with a cavity thickness of 2mm itself has fewer stratification and bubble defects, and not using the buffer structure to control the result at this time has little impact on the result), it contacts the ejector plate again at this time. The control of the distance between the initial working position of the cavity compression structure and the ejector plate is ≥0, and also includes the situation where the cavity compression structure is in contact with the ejector plate. Before the cavity filling melt process is completed, the cavity compression structure can be controlled to move earlier than the push rod, so that it has no resistance to the push rod, or the resistance is less than the injection pressure, to ensure the normal operation of the injection molding process. Preferably, the cavity compression structure does not contact the ejector plate (that is, the distance between the initial working position of the cavity compression structure and the ejector plate is >0), and it starts to contact the ejector plate after the cavity filling melt process is completed, and the cavity volume is compressed by the ejector plate, the push rod, and the push block; the distance between the initial working position of the cavity compression structure and the ejector plate is equal to 0 When, that is, the initial position of the cavity compression structure is in direct contact with the ejector plate, the bottom of the oil cylinder can also be fixed to the ejector plate (the spacing is 0), and the ejector rod of the oil cylinder supports the base (the initial position may not be in contact). By opening the bottom plate, the function of controlling the push rod to compress the cavity through the ejector plate can also be achieved; the buffer structure can be implemented using any structure familiar to those skilled in the art, and a common one is a compression spring buffer, which provides resistance through the resilience of the compression spring, or a cylinder, which provides resistance by controlling the cylinder recovery speed to be less than the speed at which the push block is pushed by the injection pressure; the cavity compression structure can be implemented using any structure familiar to those skilled in the art, including a pressure transmission device, and a common pressure transmission device includes an oil cylinder, which can be replaced by a common air cylinder, a gas-liquid booster cylinder, etc., and a power structure that can push the ejector plate to compress the cavity is selected according to demand; in addition, the pressure transmission device (such as an oil cylinder) may not be in direct contact with the ejector plate, and the function is achieved through a pressure transmission structure (such as a seesaw structure).

[0055] The specific implementation of the technical solution of the present application is further described below in conjunction with embodiments, but it is not intended to limit the claims of the present application.

[0056] Example 1

[0057] A thick part injection mold, such as Figure 2The related push block control component structure shown in the figure includes a cavity 1001, one of the side walls of the cavity is a movable push block 6, and the volume of the cavity 1001 can be changed by moving the push block 6. In this embodiment, the shape of the cavity 1001 is a cube, a push rod 5, one end of which is connected to the push block 6 and is located outside the cavity 1001, and an ejector plate 4, which is connected to the other end of the ejector plate 4; a buffer structure, in this embodiment, the buffer structure is four compression springs 2 provided at the four corners of the ejector plate 4, and a push plate guide column 3 is provided in the compression spring 2, and the push plate guide column 3 passes through the ejector plate 4, At the same time, the displacement directions of the compression spring 2 and the ejector plate 4 are limited, the initial working position of the compression spring 2 has a spacing with the ejector plate 4 of 0, that is, it is in contact with the ejector plate 4, the cavity compression structure, in this embodiment, the initial working position of the cavity compression structure has a spacing with the ejector plate greater than 0, the cavity compression structure includes a second pressure transmission device and a pressure transmission structure, wherein the second pressure transmission device is an oil cylinder 3, the pressure transmission structure is an oblique shovel transmission structure, the oblique shovel transmission structure is composed of a shovel piece 301, and an oblique block 302, the shovel piece 301 is driven by the oil cylinder 3 to move along the oblique block 302, and the oblique block 302 is fixed at the lower part of the ejector plate 4.

[0058] This embodiment 1 also includes other components of the mold, such as Figure 1 As shown, it also includes:

[0059] The bottom plate 1, the push plate guide column 201 and the compression spring 2 are arranged on the bottom plate 1; the mold foot 7 is fixed on the bottom plate 1, the cylinder 3 and the shovel piece 301 are fixed through the mold foot 7, the pad 8 is supported and fixed by two mold feet 7, one of the mold feet 7 is not shown in the figure, the B plate 10 is arranged on the pad 8, and a cavity 1001 is opened in the B plate 10. The cavity 1001 is sealed by the push block 6 toward the pad 8, and then the A plate 11 and the B plate 10 are combined to form the cavity 1001. The nozzle 12 is connected to the cavity 1001 through the A plate 11. The A plate 11 is provided with a panel 13, and also includes a water channel 9. The water channel 9 is interspersed around the nozzle 12, the cavity 1001 and the push block 6 to provide heating or cooling functions.

[0060] Operation method: In the initial position, the compression spring 2 is in contact with the ejector plate and is in a pre-stressed state; the push block 6 can be set at the top of the cavity 1001 or at a smaller distance (such as 3mm) according to the setting. If it is at the top, the entire process of the push block 6 moving toward the push rod 5 is affected by the buffering resistance of the compression spring 2. If the distance is smaller, when the melt has traveled the distance, the push block 6 is applied with thrust and is affected by the buffering resistance of the compression spring 2, that is, the compression spring 2 provides buffering resistance in part of the process; the shovel piece 301 is at the thinnest part of the inclined block 302;

[0061] During operation, the injection molding machine passes the melt through the panel 13 and the nozzle 12 into the cavity 1001, and enters the buffer structure working steps: when the cavity 1001 is filled with the melt, the injection pressure pushes the push block 6 to move in the direction of the push rod 5, and the push rod 5 transmits the injection pressure to the ejector plate 4. The buffer structure, that is, the compression spring 2, is continuously compressed as the push block 6 moves due to the injection pressure. The compression spring 2 forms a reverse thrust on the ejector plate 4, hindering the compression of the compression spring 2 by the ejector plate 4, that is, buffering the movement of the push block 6, so that when the cavity 1001 is filled with the melt, the melt is squeezed by the injection pressure and the reverse resistance of the push block 6 at the same time, thereby increasing the melt density in the cavity 1001 and reducing the stratification and pore defects generated by thick parts during cooling.

[0062] When the cavity filling melt process is finished, the water channel 9 can be used to cool part of the melt in the nozzle 12 to better prevent the thrust of the melt compression by the oil cylinder 3 from being greater than the injection pressure when working, so as to avoid the occurrence of overflow and the like, and then enter the cavity compression structure working steps: the oil cylinder 3 controls the shovel 301 to move, contact the inclined block 302, and pushes the ejector plate 4 toward the push rod 5 through the inclined block 302, thereby pushing the push block 6 to further compress the melt in the cavity 1001, further control the compression amount of the melt in the cavity 1001, increase the melt density, and reduce the stratification and pore defects in the cooling process;

[0063] The melt in the cavity 1001 is compressed to reach the target thickness and maintained under pressure for a certain period of time, and then subsequent cooling operations are performed. Then, the A plate is directly removed to eject the workpiece through the rebound force of the compression spring 2.

[0064] Example 2

[0065] The thick part injection mold described in this embodiment has the same other components as those in Embodiment 1, except for the pressure transmission structure in the structure of the push block control component, such as Figure 3 As shown, the pressure transmission structure is a seesaw transmission structure, which is composed of a fixed shaft assembly 303 and a seesaw assembly 304. One end of the seesaw assembly 304 is driven by the oil cylinder 3 and transmitted to the other end of the seesaw assembly 304 through the fixed shaft assembly 303. The other end of the seesaw assembly 304 pushes the ejector plate 4 to move toward the push rod direction, providing power for compressing the cavity 1001.

[0066] The working process is similar to that in Example 1, except that the seesaw transmission structure works, and its working principle has been shown, and those skilled in the art know how to operate it, so the detailed operation method will not be described in detail.

[0067] Example 3

[0068] The present embodiment describes a thick workpiece injection mold, the other parts of which are the same as those of the first embodiment, except that the push block control component structure does not include a cavity compression structure, but only includes a buffer structure composed of a compression spring 2. The specific structure is as follows: Figure 4 As shown, the specific working steps do not include the cavity compression structure working steps. The working principle has been shown, and those skilled in the art know how to operate it, so the detailed operating method will not be described in detail.

[0069] Example 4

[0070] The present embodiment describes a thick part injection mold, and the other parts are the same as those of the third embodiment, except that the relevant push block control component structure does not include a buffer structure, but only includes a cavity compression structure, and the cavity compression structure is a cylinder 3, which does not initially contact the ejector plate 4. When cavity compression is required, the ejector plate 4 is pushed by the cylinder 3 to compress the melt in the cavity. Among them, a limit block 202 is provided on the push plate guide column 201, which is used to limit the highest moving position of the ejector plate 4 to prevent the cylinder 3 from pushing the ejector plate 4 beyond the maximum position and damaging the mold. The specific structure is as follows Figure 5 As shown, the specific working steps do not include the buffer structure working steps. The working principle has been shown, and those skilled in the art know how to operate it, so the detailed operating method will not be described in detail.

[0071] Example 5

[0072] The thick part injection mold described in this embodiment has the same other parts as those in the third embodiment, except that the cavity compression structure part and the limit block 202 in the fourth embodiment are added. The specific structure is as follows: Figure 6 As shown, the working principle has been shown in the previous embodiments 3 and 4, and those skilled in the art know how to operate, so the detailed operation method is not described in detail. The polyhedral sample block with a thickness of 60 mm and a regular shape is obtained by injection molding in this embodiment, and the cross section is as follows Figure 8 shown.

[0073] Comparative Example

[0074] In this comparative example, a conventional injection mold is used, which is directly designed as a cavity with a fixed thickness (60 mm in this comparative example), and the following is obtained by injection molding: Figure 7 The structure of this comparative example is a conventional injection mold structure, and those skilled in the art know how to implement it, so it will not be described in detail.

[0075] From the cross-section of the sample blocks of the same specification and size injected in the comparative example and in Example 5, a large number of pores and delamination defects appeared in the comparative example, while the sample block injected in Example 5 had almost no pores and the delamination was significantly improved, which further proves the beneficial effect of the technical solution of the present application.

[0076] It should be noted that the mold placement in the embodiments of the present application can be placed vertically or horizontally according to needs, and the directional words such as upper and lower are said according to the structure in the specific embodiments, but are not intended to limit the scope of protection of the present application.

[0077] The embodiments described in the specific implementation manner of this application are merely examples of the technical solution of this application. Any non-inventive changes or equivalent changes made based on the features and principles described in the technical solution of this application are included in the protection scope of this application.

Claims

1. A thick part injection mold, characterized in that: include: A cavity, one of the side walls of the cavity is a movable push block, and the volume of the cavity can be changed by moving the push block. A push rod, one end of which is connected to the push block and is located outside the cavity. An ejector plate connected to the other end of the push rod, Buffer structure and / or cavity compression structure, The initial working position of the buffer structure has a distance of ≥0 from the ejector plate. When the distance between the ejector plate and the buffer structure is 0, the ejector plate is in contact with the buffer structure. The buffer structure can drive the ejector plate to move when the push block moves toward the push rod. The buffer structure can apply a buffer thrust to the ejector plate in the opposite direction of the movement of the ejector plate, so that the push block has a buffer resistance in the process of moving toward the push rod. The distance between the initial working position of the cavity compression structure and the ejector plate is ≥ 0. When the distance between the ejector plate and the cavity compression structure is 0, they are in a contact state. The cavity compression structure can apply a thrust to the ejector plate in the opposite direction of the movement of the ejector plate by contacting the ejector plate, so that the push block moves toward the inside of the cavity. The buffer structure is one or more elastic elements or a first pressure transmission device; or The buffer structure is one or more elastic elements and a first pressure transmission device; The elastic element is in a pre-stressed state during operation, and the first pressure transmission device can apply a thrust or a pull to the ejector plate, and the thrust or the pull can apply a buffer thrust to the ejector plate in the opposite direction of the movement of the ejector plate, so that the push block has a buffer resistance in the process of moving toward the push rod; The cavity compression structure is one or more second pressure transmission devices; or The cavity compression structure is composed of one or more second pressure transmission devices and a pressure transmission structure. The pressure transmission structure is driven by a second pressure transmission device, and is connected to the ejector plate by contact, so as to apply a thrust to the ejector plate in the opposite direction of the movement of the ejector plate, so that the push block moves toward the inside of the cavity. The pressure transmission structure is a seesaw transmission structure or an inclined shovel transmission structure.

2. The thick part injection mold according to claim 1, characterized in that: The buffer structure is one or more elastic elements and one or more first pressure transmission devices, one of the elastic element and the first pressure transmission device is in contact with the ejector plate, and the elastic element and the first pressure transmission device are in a series superposition state. or The elastic element and the first pressure transmission device are both in contact with and connected to the ejector plate, and the elastic element and the first pressure transmission device are in a parallel state.

3. The thick part injection mold according to claim 1, characterized in that: The elastic element is one or more of a compression spring, a disc spring, and a nitrogen spring.

4. The thick part injection mold according to claim 1, characterized in that: The cavity compression structure is one or more second pressure transmission devices.

5. The thick part injection mold according to any one of claims 1 to 4, characterized in that: The first pressure transmission device or the second pressure transmission device is a hydraulic device, a pneumatic device or a gas-liquid mixed pressure device.

6. The thick part injection mold according to claim 1, characterized in that: A temperature increasing device is arranged outside the cavity.

7. A method for operating a thick workpiece injection mold as claimed in claim 1, characterized in that: Corresponding to the buffer structure and / or the cavity compression structure, the buffer structure working steps and / or the cavity compression structure working steps are included: The buffer structure has the following working steps: when the cavity is filled with melt, during part or all of the process in which the push block moves toward the push rod, the buffer structure applies a buffer thrust to the ejector plate in the opposite direction of the ejector plate, and transmits the buffer thrust to the push block via the push rod, so that the push block has a buffer resistance in the process of moving toward the push rod; Working steps of the cavity compression structure: when the cavity filling melt process is completed, the cavity compression structure applies a thrust or a pull to the ejector plate, which is transmitted to the push block via the push rod, thereby pushing the push block to move toward the inside of the cavity.

8. An operating method according to claim 7, characterized in that: The working steps of the cavity compression structure also include a gate cooling process, and the gate cooling process is performed after the cavity filling melt process is completed and before the cavity compression structure works.

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