A multi-shot shear profile molding die

Abstract

The present application provides a kind of multiple injection shear sample forming die, by setting first cavity and second cavity of terminal overlap, and the switching slider that can realize first cavity and second cavity communication or separate, and the switching insert that realizes second runner and second cavity communication or disconnect, can complete in sequence in two cavity respectively independent injection molding, and in two cavity overlapping portion (double cavity) realize twice injection remelt, form fusion interface, obtain shear sample;The shear sample obtained is stretched by universal testing machine Shear test, and the shear strength is obtained, which is used to evaluate the performance of the fusion interface formed by the insert injection molding of any two materials. The influence law of different factors on the performance of the fusion interface obtained by the experiment can be used to guide the actual product production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of multi-shot injection molding, and particularly relates to a multi-shot shearing sample forming mold. BACKGROUND

[0002] With the development of high-end manufacturing industry and the increasing demand for thick-walled polymer injection molding products in the national pillar industry, such as super-thick car lights and super-thick windows of manned deep submersibles. However, the thickness of the conventional injection molding process is generally below 6 mm. A larger thickness will cause a large difference between the surface temperature and the core layer temperature of the melt in the thickness direction during the cooling process of the product. The core layer temperature of the plastic part is high, the cooling is slow, the shrinkage is large, the surface layer cools faster, and the phenomenon of uneven shrinkage will occur, and even vacuum bubbles and other defects will occur. At the same time, due to uneven cooling and many shrinkage defects, a large residual stress will be generated, which will affect the dimensional accuracy of the thick-walled product.

[0003] In recent years, multi-layer injection molding technology has been applied to the forming of thick-walled polymers. Multi-shot injection molding technology converts thick-walled products into multiple thin-walled products by discretizing the thick-walled products. It can effectively reduce the defects generated by conventional injection molding of thick-walled products, and can also shorten the forming cycle, which has attracted widespread attention in the industry. Multi-shot injection molding involves sequentially injecting melt into the mold cavity in each forming process. Heat exchange occurs between the newly injected melt and the solidified substrate, causing the substrate temperature to rise and re-melting. Due to heat exchange during filling, the internal energy of the melt gradually decreases, causing the re-melted area to gradually thin along the flow direction. In the contact area between the substrate and the melt, due to the violent movement and molecular diffusion of the melt molecules, the molecular chains on the contact surface begin to relax and then entangle with each other, and then move along the melt flow direction. The condensed layer in the substrate plays a role in preventing the integration of the molecules of the other party and itself, affecting the complete and uniform mixing of the two melt flows, resulting in different local microstructures in the contact section. With the entanglement and migration of molecules between the contact surfaces, a nearly planar trace will appear macroscopically, i.e. a fusion interface is formed, which affects the performance of the product, especially the mechanical properties.

[0004] As a new technology, the theory, method and experimental research of multi-shot injection molding technology are not mature, especially in the performance evaluation of fusion interface. It is of great significance to analyze the changes of the aggregate structure at the fusion interface of multi-shot injection molding for improving the injection process and improving the performance of products. Shear strength is an important indicator to measure the interface strength performance, which is generally tested according to the standards GB / T 33334 and ISO 4587, and the standard shear sample needs to be used when the two detection standards are tested. However, the multi-shot injection device in the prior art generally increases the number of injections by increasing the injection unit or injection station, so it is impossible to prepare the standard shear sample for tensile shear strength test on the ordinary injection molding machine, and then the interface performance analysis such as shear strength and morphology cannot be carried out. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a multi-shot shear sample forming mold, which can realize the preparation of standard multi-shot injection molding shear sample and meet the test requirements of the shear strength of the fusion interface of multi-shot injection molding products.

[0006] A multi-shot shear sample forming mold, comprising a movable die core and a fixed die core;

[0007] Further comprising:

[0008] A first cavity and a second cavity are arranged on the movable die core, and the ends of the first cavity and the second cavity overlap to form a double-layer cavity;

[0009] A main flow channel, and a first flow channel and a second flow channel respectively communicating with the end of the main flow channel; the ends of the first flow channel and the second flow channel are respectively connected to the first cavity and the second cavity;

[0010] A switching insert arranged in the movable die core and corresponding to the end of the second flow channel, the switching insert can rotate relative to the movable die core to realize the connection or disconnection of the second flow channel and the second cavity;

[0011] A switching slider slidingly arranged between the fixed die core and the movable die core, the switching slider is provided with a groove corresponding to the end of the second cavity; under the action of external force, the switching slider moves to realize the coincidence or misalignment of the groove and the second cavity, so as to realize the communication or isolation of the ends of the first cavity and the second cavity.

[0012] In the above forming mold, the first cavity is arranged away from the fixed mold core, and the second cavity is arranged close to the fixed mold core. Before injection, the switching insert is in a position to disconnect the second runner and the second cavity, and the switching slider is in a position to disconnect the first cavity and the second cavity by staggering the groove and the second cavity. After the first injection, a first layer is formed in the first cavity. Then, the mold is opened, the switching insert is rotated to connect the second runner and the second cavity, and the switching slider is slid to overlap the groove and the second cavity to connect the first cavity and the second cavity. Then, the second injection is performed, the flow end of the second injection melt overlaps the end of the first layer in the double-layer cavity to form a fusion interface, and the mold is opened to obtain a shear specimen. Wherein, the overlapping or staggering of the groove and the second cavity refers to complete overlapping or complete staggering.

[0013] In the forming mold of the present application, the first cavity and the second cavity are arranged in sequence with their ends overlapping, and the injection is performed twice in sequence in the first cavity and the second cavity respectively. The switching insert is rotated and the switching slider is slid to achieve independent injection of the first cavity and the second cavity. The first injection product serves as the substrate for the second injection, and the products of the two injections are remelted and bonded in the overlapping part (double-layer cavity) of the two cavities to form a fusion interface, and then a standard multi-injection shear specimen is obtained.

[0014] The obtained standard shear specimen is tested on a universal testing machine, the shear strength is obtained by the ratio of the maximum tensile force that can be withstood to the bonding area (fusion interface area), and the calculation formula is as follows:

[0015]

[0016] Among them, represents the shear strength, represents the maximum tensile force that can be withstood, represents the bonding area (i.e. the area of the fusion interface).

[0017] In addition, the microstructure of the fusion interface of the shear specimen can be observed by a scanning electron microscope, so as to evaluate the interface performance of the multi-injection molding.

[0018] During the preparation process, different shear specimens can be obtained by changing the process parameters during injection. By testing the performance of different shear specimens, the influence of different process parameters on the performance of the fusion interface can be analyzed, and then the production can be guided.

[0019] As a preferred, the first cavity and the second cavity are both rectangular grooves, and the sizes are equal. The sizes of the first cavity and the second cavity are set according to the size of the standard shear specimen. The sizes equal means that the depth, width and length are all equal.

[0020] As a preference, the side of the switching slider away from the side surface of the fixed die core is in the same plane as the overlapping surface of the second cavity and the first cavity. This ensures that the first cavity is not affected when the first cavity and the second cavity are separated.

[0021] As a preference, the groove is open on the side away from the first cavity, and the open side is between the first end of the second cavity and the end of the first cavity. The side of the groove close to the first cavity is between the end of the first cavity and the end of the second cavity and at most extends to the end of the second cavity. The side of the groove away from the first cavity is open to allow the melt to smoothly enter the double-layer cavity during the second injection, to achieve multiple injection products and form a fusion interface. To ensure the standard degree of the shear specimen, the side of the groove close to the first cavity can at most be aligned with the end of the second cavity.

[0022] The position of the side of the groove close to the first cavity can be adjusted as needed. For example, different lengths of grooves can be machined on multiple switching sliders (the position of the side of the groove close to the second cavity is fixed), the fusion interface area of the shear specimen can be changed by replacing the switching slider with a groove of different length, thereby achieving the preparation of injection-molded shear specimens with different overlap lengths. In addition, first cavities and second cavities with different depths can be machined on multiple movable die cores, and switching sliders with corresponding groove depths can be provided. Different thickness shear specimens can be prepared by replacing the movable die core and the corresponding switching slider; preventing the single layer of the shear specimen from being too thin, which can result in the strength of the matrix (single layer) being less than the shear strength of the fusion interface, thereby meeting the needs of multiple injection-molded fusion interface performance evaluation shear specimens of different materials.

[0023] As a preference, the width and depth of the groove are the same as those of the second cavity. This ensures that the size of the fusion interface is regular.

[0024] As a preference, the molding mold further comprises a fixed die support plate and a movable die support plate for mounting the fixed die core and the movable die core, respectively. One side of the fixed die support plate is provided with a fixed die side plate and a T-shaped push rod. One end of the push rod penetrates the fixed die side plate in the thickness direction and is connected with the switching slider.

[0025] The side of the fixed die support plate close to the movable die support plate is provided with double guide rails perpendicular to the second cavity and the fixed die side plate, respectively. The switching slider is slidingly connected with the double guide rails. The push rod can drive the switching slider to move along the double guide rails under the action of an external force, to realize the coincidence or misalignment of the groove and the second cavity.

[0026] During injection, the movement of the switching slider can be realized by pushing and pulling the push rod by a mechanical hand or manually.

[0027] As a further preference, the switching slider is connected with the push rod through a connecting block. The connecting block is fixedly connected with the push rod and detachably connected with the switching slider.

[0028] The switching slider is located between the double guide rails, and the corresponding two sides of the connecting block are respectively slidably connected with the double guide rails.

[0029] When the shear sample is prepared, different shear sample fusion areas can be prepared by directly replacing the switching slider corresponding to the groove; the switching slider is detachably connected with the connecting block, thereby improving the replacement efficiency of the switching slider.

[0030] Preferably, the ends of the first flow channel and the second flow channel are respectively connected with the first end of the first cavity and the second end of the second cavity through the gates.

[0031] The gate corresponding to the second flow channel is arranged on the switching insert, and the switching insert is capable of driving the corresponding gate to connect or disconnect the second flow channel and the second cavity.

[0032] Specifically, the switching insert can be arranged in a cylindrical structure, the central axis of which is arranged in the thickness direction of the mold core, and the gate is arranged on the end face thereof. The switching insert is rotated by an external force to make the gate connect or disconnect the second flow channel and the second cavity.

[0033] Preferably, the molding mold further comprises a fixed mold pulling plate and a fixed mold plate arranged in sequence on the side of the fixed mold support plate away from the movable mold support plate, the inlet of the main flow channel is arranged on the fixed mold plate, and a positioning ring for positioning the molding mold on the injection machine is arranged on the fixed mold plate at the inlet of the main flow channel.

[0034] The ejector plate, the movable mold plate arranged on the side of the movable mold support plate away from the fixed mold support plate, the two mold feet arranged between the movable mold plate and the movable mold support plate, and the ejector pins arranged on the ejector plate are arranged, and the ejector pins correspond to the first cavity and the second cavity.

[0035] The fixed mold plate is arranged on the fixed mold plate of the injection machine, and the movable mold plate is arranged on the movable mold plate of the injection machine. The two mold feet are arranged on the opposite sides between the movable mold plate and the movable mold support plate, and are respectively fixedly connected with the movable mold plate and the movable mold support plate. The ejector plate is arranged on the side opposite to the movable mold plate and the movable mold support plate. The four corners of the ejector plate are respectively provided with an ejector pin guide column and a spring sleeved on the ejector pin guide column, and the ejector pin guide column is fixed through the movable mold support plate. The ejector plate moves along the ejector pin guide column under the action of an external force to eject the product. After ejection, the external force is removed and the spring potential energy is restored to the initial position.

[0036] It is worth noting that the technical solution of the present application is intended to focus on the innovative structure of the mold core and the flow channel, and other existing conventional structures in the mold are not described in detail. In addition, the end and the head in this article refer to the direction of the melt flow during injection.

[0037] The injection molding of the forming mold of the present application uses a common cold runner, and the glue is injected from the product edge side through a pin point gate (the end of the distribution channel), and the multiple glue injection in the mold shares the main runner and the same gate, and the front and rear two injections respectively use different side distribution channels (the first runner and the second runner). A mold pulling plate is arranged between the fixed mold plate and the fixed mold support plate, and part of the first runner and the second runner is located between the fixed mold support plate and the fixed mold pulling plate; when the mold is opened, the fixed mold support plate and the fixed mold pulling plate are separated, and the solidified cold runner waste is left between the fixed mold pulling plate and the fixed mold support plate, which can be taken out by a mechanical hand or manually, without the need for a redundant runner cutting device.

[0038] The forming mold provided by the present application can realize the switching of two different cavity states. After the first injection is completed, the runner (switching insert) and the cavity (switching slider) are switched by a mechanical hand or manually, and the waste remaining in the runner after the last injection is removed, so as to ensure that the runner is unobstructed during the next injection. The continuous injection molding of a single melt can be realized, and a shear bar for evaluating the interface performance of multi-injection molding can be manufactured. The mold structure is simple, the operation is fast, the injection equipment and mold cost are saved, and the shear bar formed can be used for researching the fusion interface performance of multi-injection molding.

[0039] In addition, the structure of the mold core and the runner of the forming mold of the present application during each injection is similar to that of a common forming mold, and the movable mold and the fixed mold are always in the closed mold state during the entire injection molding process, without the need for an additional injection unit, so that the existing common single screw injection molding equipment can be used, without the need for complex molding equipment. The multi-injection molding shear bar forming mold provided by the present application has a simple structure and is convenient to operate, can realize the continuous and efficient production of multi-injection molding shear bars, is used for evaluating the performance of the fusion interface, reduces the cost of products, molds and injection equipment, solves the problem that the existing multi-injection molding equipment cannot prepare standard shear bars for testing, and realizes the guidance of the multi-injection molding production process according to the detection of the fusion interface performance.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] The multi-injection shear spline molding die of the present invention, by setting up a first cavity and a second cavity with overlapping ends, a switching slider that can connect or separate the first cavity and the second cavity, and a switching insert that can connect or disconnect the second flow channel and the second cavity, can complete the sequential independent injection molding in the two cavities, and achieve two injection remeltings in the overlapping part of the two cavities (double-layer cavity) to form a fusion interface and obtain a shear spline. The obtained shear spline is subjected to a tensile shear test in a universal testing machine to obtain the shear strength, which is used to evaluate the performance of the fusion interface formed by insert injection molding of any two materials. The influence of different factors on the performance of the fusion interface obtained from the experiment can be used to guide the actual product production. Attached Figure Description

[0042] Figure 1 This is a cross-sectional view of an embodiment of the present invention;

[0043] Figure 2 This is a cross-sectional view from another angle of an embodiment of the present invention;

[0044] Figure 3 This is a cross-sectional view of the mold core and flow channel in an embodiment of the present invention;

[0045] Figure 4 This is a cross-sectional view of the mold core and flow channel portion from another angle in an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the moving mold, switching slider, and flow channel structure in an embodiment of the present invention;

[0047] Figure 6 This is a diagram of the tensile shear spline prepared in an embodiment of the present invention.

[0048] In the diagram: 1-Fixed mold core, 11-Fixed mold support plate, 12-Fixed mold pull plate, 13-Fixed template, 14-Positioning ring, 2-Moving mold core, 21-First cavity, 22-Second cavity, 23-Layered cavity, 24-Switching insert, 25-Gate, 26-Moving mold support plate, 27-Ejector plate, 28-Moving template, 29-Ejector pin, 210-Spring, 211-Mold foot, 3-Main runner, 31-First runner, 32-Second runner, 4-Switching slider, 41-Groove, 42-Guide rail, 43-Fixed mold side plate, 44-Push rod, 45-Connecting block. Detailed Implementation

[0049] The following is in conjunction with the instruction manual appendix. Figures 1-6 The technical solution of the present invention will be further illustrated through specific embodiments. These embodiments are descriptive and not limiting, and should not be used to limit the scope of protection of the technical solution of the present invention.

[0050] like Figure 1 and2 As shown in the figure, a multi-injection shear sample forming mold includes a fixed mold plate 13, a fixed mold pulling plate 12, a fixed mold support plate 11, a fixed mold core 1, a movable mold core 2, a movable mold support plate 26, two mold feet 211, a ejector plate 27, a plurality of ejector pins 29 and a movable mold plate 28 arranged in sequence. The fixed mold core 1, the fixed mold support plate 11, the fixed mold pulling plate 12 and the fixed mold plate 13 together constitute a fixed mold assembly; the movable mold core 2, the movable mold support plate 26, the two mold feet 211, the ejector plate 27, the plurality of ejector pins 29 and the movable mold plate 28 together constitute a movable mold assembly.

[0051] Among them, the fixed mold support plate 11 and the movable mold support plate 26 are respectively used for installing the fixed mold core 1 and the movable mold core 2; the fixed mold support plate 11 is connected with the movable mold support plate 26 through the support guide columns arranged at the four corners thereof, and the movable mold support plate 26 moves along the support guide columns to approach or move away from the fixed mold support plate 11 under the action of the external force of the injection machine, so as to realize the opening and closing of the mold. The two mold feet 211 are arranged on the opposite sides between the movable mold plate 28 and the movable mold support plate 26, and are respectively fixedly connected with the two; the ejector plate 27 is arranged on the side opposite to the movable mold plate 28 and the movable mold support plate 26; the four corners of the ejector plate 27 are respectively provided with an ejector pin guide column and a spring 210 sleeved on the ejector pin guide column, and the ejector pin guide column is fixed through the movable mold support plate 26. The ejector plate 27 moves along the ejector pin guide column to compress the spring 210 under the action of the external force, so as to eject the product; after ejection, the external force is removed, and the ejector plate 27 returns to the initial position under the action of the potential energy of the spring 210.

[0052] As shown in the figure, Figures 3-5 A main flow channel 3 and two sub-flow channels are arranged inside the fixed mold assembly, and part of the two sub-flow channels is located between the fixed mold support plate 11 and the fixed mold pulling plate 12; the two sub-flow channels are respectively used as a first flow channel 31 and a second flow channel 32, the first ends of the two are respectively communicated with the end of the main flow channel 3, and a positioning ring 14 is arranged on the fixed mold plate 13 corresponding to the inlet of the main flow channel 3.

[0053] The movable mold core 2 is provided with two rectangular grooves with the same size, and the rectangular groove away from the fixed mold core 1 is used as a first cavity 21, and the other rectangular groove is used as a second cavity 22; the first cavity 21 and the second cavity 22 are arranged in parallel and the ends overlap, and the overlapping part of the two forms a double-layer cavity 23 for forming a layered structure. The ends of the first flow channel 31 and the second flow channel 32 are respectively connected with the first ends of the first cavity 21 and the second cavity 22 through the sprue 25.

[0054] The installation hole corresponding to the end of the second flow channel 22 is arranged in the center axis direction of the moving die core 2, and the switching insert 24 is arranged in the installation hole. The switching insert 24 can rotate in the installation hole relative to the moving die core 2, and the gate 25 corresponding to the second flow channel 32 is arranged on the end face of the switching insert 24 close to the second flow channel 32. The switching insert 24 rotates under the action of an external force, and can realize the butt joint or disconnection of the corresponding gate 25 to the second flow channel 32 and the second cavity 22. In the embodiment, the switching insert 24 is arranged in a cylindrical structure, and the gate 25 is arranged on the end face thereof. When the second layer injection is performed, the switching insert 24 is rotated to make the gate 25 butt joint with the second flow channel 32 and the second cavity 22 respectively, so that the second flow channel 32 and the second cavity 22 are communicated (as shown in Figure 3 and 5 shown); then the switching insert 24 is reversely rotated around its own axis to return to the initial state, that is, the second flow channel 32 and the second cavity 22 are disconnected.

[0055] The switching slider 4 is arranged between the fixed die core 1 and the moving die core 2 and slides at the end of the second cavity 22. The side of the switching slider 4 away from the fixed die core 1 is provided with a groove 41 corresponding to the end of the second cavity, and the side of the switching slider 4 provided with the groove 41 is arranged in the same plane as the overlapping surface of the second cavity 22 and the first cavity 21. The width and depth of the groove 41 are the same as those of the second cavity 22. The switching slider 4 slides under the action of an external force, and can drive the groove 41 to coincide with or be offset from the second cavity 22, so that the ends of the first cavity 21 and the second cavity 22 are communicated or separated. The side of the groove 41 away from the first cavity 21 is open, and the opening side is located between the first end of the second cavity 22 and the end of the first cavity 21. The side of the groove 41 close to the first cavity 21 is located between the ends of the first cavity 21 and the second cavity 22 and extends at most to the end of the second cavity 22.

[0056] The position of the side of the groove 41 close to the first cavity 21 can be adjusted as needed. For example, grooves 41 of different lengths are machined on the switching sliders 4 (the position of the side of the groove 41 close to the second cavity is fixed), the fusion interface area can be changed by replacing the switching slider 4 with a groove 41 of a different length, so that injection molding shear specimens of different overlap lengths can be prepared. In addition, the first cavity 21 and the second cavity 22 of different depths are machined on the moving die core 2, and the switching slider 4 with a groove 41 of a corresponding depth is arranged. The preparation of shear specimens of different thicknesses can be realized by replacing the moving die core 2 and the corresponding switching slider 4; the shear specimen is prevented from being too thin in a single layer, so that the strength of the substrate (single layer) is smaller than the shear strength of the fusion interface, thereby meeting the needs of the performance evaluation of the fusion interface of multiple injection molding shear specimens of different materials.

[0057] The side of the fixed mold support plate 11 is provided with a fixed mold side plate 43 and a T-shaped push rod 44, one end of the push rod 44 vertically penetrates along the thickness direction of the fixed mold side plate 43 and is connected with the switching slider 4 through a connecting block 45; the side of the fixed mold support plate 11 close to the movable mold support plate 26 is provided with double guide rails 42 which are perpendicular to the second cavity 22 and the fixed mold side plate 43 respectively, and the corresponding two sides of the connecting block 45 are respectively connected with the double guide rails 42 in sliding mode; the connecting block 45 is fixedly connected with the push rod 44 and is detachably connected with the switching slider 4. By replacing the switching slider 4 with different sizes of grooves 41, shear samples with different fusion interface areas can be prepared; the switching slider 4 is detachably connected with the connecting block 45, thereby improving the replacement efficiency of the switching slider 4.

[0058] After installation, the switching slider 4 is located between the double guide rails 42, the push rod 44 is pushed and pulled by a mechanical hand or manually to move the switching slider 4 along the double guide rails 42, and the coincidence or misalignment of the groove 41 and the second cavity 22 is realized.

[0059] After the mold is opened after cooling, the pin-point gate (the end of the runner) is easy to realize the separation of the product and the runner during injection, the fixed mold support plate 11 and the fixed mold pulling plate 12 are separated, and the runner waste is taken out from between the fixed mold support plate 11 and the fixed mold pulling plate 12 by an external mechanical hand or manually.

[0060] The installation and injection molding process of the above-mentioned multiple injection shear sample forming mold on the injection machine are as follows:

[0061] Firstly, the above-mentioned forming mold is installed on the injection machine: a common injection machine with a single injection unit can meet the product forming requirements. The fixed mold plate 13 is installed on the fixed mold plate of the injection machine, and is positioned with the injection machine through the positioning ring 14, and the pouring port sleeve on the fixed mold plate 13 directly contacts with the nozzle of the injection machine; the movable mold plate 29 is installed on the movable mold plate of the injection machine.

[0062] When the injection starts, the mold is in the closed mold state, at this time, the switching slider 4 and the switching insert 24 are both in the initial state, that is, the switching slider 4 is in the position where the groove 41 is completely misaligned with the second cavity 22, and separates the first cavity 21 and the second cavity 22, as shown in Figure 4 The switching insert 24 is in the position of disconnecting the second runner 32 and the second cavity 22, so that the second runner 32 is closed; the product is not connected between the second cavity 22 and the first cavity 21, and the first layer of the shear sample is injected. When the first layer injection is completed, the pressure is maintained and cooled, the mold is opened, and the runner waste generated by the first injection is removed from between the fixed mold support plate 11 and the fixed mold pulling plate 12 by a mechanical hand or manually.

[0063] The mechanical hand or the artificial pushes the push rod 44, and the switching slider 4 is moved to the direction of the second cavity 22 to make the recess 41 completely coincide with the second cavity 22, at this time, the first cavity 21 and the second cavity 22 are communicated. At the same time, the switching insert 24 is rotated around its own axis by the mechanical hand or the artificial, and the gate 25 on the switching insert 24 is respectively connected to the second runner 32 and the second cavity 22.

[0064] After all the adjustments are completed, the mold is closed, and the second injection is carried out. The second injection melt realizes the remelting and combination with the first layer in the two-cavity communication area (double-layer cavity 23), and a fusion interface is formed. After the second injection molding is completed, the shear sample for tensile strength test of the two-layer injection molding is formed, the pressure is maintained and cooled, the mold is opened, and the product is ejected by the ejector pin 29 driven by the ejector plate 27. At the same time, similar to the first injection, the runner waste produced by the second injection is taken out by the mechanical hand or the artificial, and the push rod 44 and the switching insert 24 are respectively restored to the initial state by pulling back and rotating in the opposite direction, so as to carry out the injection molding of the next shear sample. The above steps are repeated to realize the continuous production of the shear sample.

[0065] The standard shear sample obtained is tested on a universal testing machine, the shear strength is obtained by the ratio of the maximum tensile force that can be borne to the bonding area (the area of the fusion interface), and the calculation formula is as follows:

[0066]

[0067] Among them, represents the shear strength, represents the maximum tensile force that can be borne, represents the bonding area (that is, the area of the fusion interface).

[0068] In addition, the microstructure of the fusion interface of the shear sample can also be observed by a scanning electron microscope, so as to evaluate the interface performance of the layered injection molding.

[0069] During the preparation process, different shear samples can be obtained by changing the process parameters during injection or replacing the switching slider or simultaneously replacing the movable mold core and the switching slider. The performance of different shear samples is tested, the influence of different process parameters on the performance of the fusion interface is analyzed, and then the production is guided.

[0070] A plurality of shear samples with different fusion cross-section lengths prepared by using the above device and injection method are as shown in Figure 6 .

[0071] The above shows and describes the basic structure and working principle of the present application. It should be noted here that although the present application has been described in detail, any similar modifications made on the basis of the present application by relevant personnel in the field shall fall within the protection scope of the present application.

Claims

1. A multi-injection shear sample forming mold, comprising a movable mold core and a fixed mold core; characterized in that Further comprising: a first cavity and a second cavity provided on the movable mold core, the ends of the first cavity and the second cavity overlapping to form a double-layer cavity; a main runner, and a first runner and a second runner respectively communicating with the ends of the main runner; the ends of the first runner and the second runner respectively corresponding to the ends of the first cavity and the second cavity; a switching insert provided in the movable mold core and corresponding to the end of the second runner, the switching insert being rotatable relative to the movable mold core to realize the connection or disconnection of the second runner and the second cavity; a switching slider slidingly provided between the fixed mold core and the movable mold core, the switching slider being provided with a groove corresponding to the end of the second cavity; the switching slider moving under the action of an external force to realize the coincidence or misalignment of the groove and the second cavity, so as to realize the communication or separation of the ends of the first cavity and the second cavity.

2. The multi-shot shear profile strip forming die of claim 1, wherein, The first cavity and the second cavity are both rectangular grooves and have equal sizes.

3. The multi-shot shear profile molding die of claim 1, wherein, The side of the switching slider away from the fixed mold core is in the same plane as the overlapping surface of the second cavity and the first cavity.

4. The multi-shot shear profile molding die of claim 1, wherein, The groove is open on the side away from the first cavity, and the open side is located between the end of the first cavity and the end of the second cavity; the side of the groove close to the first cavity is located between the ends of the first cavity and the second cavity and at most extends to align with the end of the second cavity.

5. The multi-shot shear profile molding die of claim 1, wherein, The width and depth of the groove are the same as those of the second cavity.

6. The multi-shot shear profile molding die of claim 1, wherein, Further comprising a fixed mold support plate and a movable mold support plate respectively used for mounting the fixed mold core and the movable mold core, one side of the fixed mold support plate being provided with a fixed mold side plate and a T-shaped push rod, one end of the push rod being vertically penetrated along the thickness direction of the fixed mold side plate and connected with the switching slider; the side of the fixed mold support plate close to the movable mold support plate being provided with double guide rails perpendicular to the second cavity and the fixed mold side plate respectively, the switching slider being slidingly connected with the double guide rails, and the push rod being capable of driving the switching slider to move along the double guide rails under the action of an external force to realize the coincidence or misalignment of the groove and the second cavity.

7. The multi-shot shear profile molding die of claim 6, wherein, The switching slider is connected with the push rod through a connecting block, the connecting block being fixedly connected with the push rod and detachably connected with the switching slider; The switching slider is located between the double guide rails, and the corresponding two sides of the connecting block are slidingly connected with the double guide rails respectively.

8. The multi-shot shear profile molding die of claim 1, wherein, The ends of the first runner and the second runner are respectively connected with the ends of the first cavity and the second cavity through sprues; the sprue corresponding to the second runner being provided on the switching insert, and the switching insert being capable of driving the corresponding sprue to connect or disconnect the second runner and the second cavity by rotating.

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