Injection mold for thermosetting plastic molding

Abstract

The invention relates to the technical field of injection molds, in particular to an injection mold for thermosetting plastic molding, which comprises a movable mold, a fixed mold, a pressure control ring, a pressure control spring, a flow control spring, a flow control rod and an air cylinder, the movable mold is internally provided with a movable cavity, the fixed mold comprises a fixed body, a feeding channel and a fixed cavity, the fixed body is arranged on the left side of the movable mold, and the feeding channel is arranged on the right side of the fixed cavity. The feeding channel and the fixed cavity are formed in the fixed body from left to right, the pressure control ring is installed on the right end face of the fixed body, the pressure control spring is arranged between the pressure control ring and the fixed body, the flow control rod is inserted into the feeding channel, the flow control spring is installed on the flow control rod, and the air cylinder is arranged on the right side of the movable mold. By gradually reducing the volume of the cavity of the injection mold and applying a large area of force to the flow-state plastic in the injection mold, the purposes of increasing the internal pressure of the injection mold and uniformly distributing the flow-state plastic so as to improve the quality of a formed product are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of injection molds, in particular to an injection mold for thermosetting plastic molding. Background Art

[0002] Plastics can be divided into thermoplastics and thermosetting plastics according to their internal molecular structure. During the injection molding process, fluid thermoplastics cool and solidify in the injection mold, and the molded product can restore fluidity by reheating, while fluid thermosetting plastics will continue to be heated inside the mold to complete the cross-linking and curing reaction, and the molded product cannot restore fluidity. Therefore, thermosetting plastics have the characteristics of high hardness, high temperature resistance and corrosion resistance, and are widely used in electronic device housings, engine components, circuit breakers and other fields.

[0003] The melting point of thermosetting plastics is higher than the degradation temperature, and a cross-linking curing reaction will occur when heated to a certain temperature. Therefore, the heating temperature of thermosetting plastics during the extrusion process is generally lower than that of thermoplastics. In addition, thermosetting plastics are limited by their own tight molecular structure and have even poorer fluidity, which means that it is difficult for thermosetting plastics to completely fill the mold, resulting in poor quality of the molded product. Therefore, the prior art will try to increase the pressure (i.e., feed pressure) when the thermosetting plastic enters the mold. For example, in a high-pressure injection molding device for producing a server chassis shell with publication number CN115091703B, a pressure injection device is provided between the injection mold and the extrusion device to discharge the thermosetting plastic in the extrusion device into the injection mold at high pressure.

[0004] The existing technology can make thermosetting plastics have stronger flowability by increasing the feed pressure so as to fill the cavity of the injection mold. However, when injecting thermosetting plastics with poor fluidity (such as unsaturated polyester resin), there are still obvious problems that need to be improved: thermosetting plastics with poor fluidity also have poor pressure transmission effect. Therefore, the plastic close to the injection mold feed port will be subjected to greater pressure, and the mold feed port only occupies a limited area of ​​the mold cavity wall. Therefore, the plastic cannot transmit pressure over a large area, which makes the pressure transmission effect in the mold cavity worse, thereby making the pressure distribution in the mold cavity more uneven, resulting in uneven plastic concentration in various parts of the mold cavity, and then causing different performance of the molded product in various parts, thereby inducing quality problems.

[0005] In order to make the thermosetting plastic more evenly distributed inside the injection mold so as to obtain a molded product with higher quality, an injection mold for molding thermosetting plastic is provided. Summary of the invention

[0006] The purpose of the present invention is to provide an injection mold for thermosetting plastic molding, which solves the problem that thermosetting plastics with poor fluidity are difficult to be evenly distributed in the injection mold. By gradually reducing the volume of the injection mold cavity and applying force to the fluid plastic in the injection mold over a large area, the internal pressure of the injection mold is increased and the fluid plastic is evenly distributed, thereby improving the quality of the molded product.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] An injection mold for thermosetting plastic molding, comprising a movable mold, a movable cavity is arranged in the movable mold, and also comprises a fixed mold, a pressure control ring, a pressure control spring, a flow control spring, a flow control rod and a cylinder, the fixed mold comprises a fixed body, a feed channel and a fixed cavity, the fixed body is arranged on the left side of the movable mold, the feed channel and the fixed cavity are arranged inside the fixed body from left to right, the pressure control ring is installed on the right end surface of the fixed body, the pressure control spring is arranged between the pressure control ring and the fixed body, the flow control rod is inserted into the feed channel, the flow control spring is installed on the flow control rod, and the cylinder is arranged on the right side of the movable mold;

[0009] The pressure-control ring is pre-pressed by the movable mold to merge the movable cavity and the fixed cavity. The fluid plastic in the feed channel pushes the flow-control rod due to the feed pressure and flows to and gradually fills the fixed cavity and the movable cavity. The flow-control rod that loses the feed pressure moves to the left and separates the feed channel and the fixed cavity due to the return elastic force of the flow-control spring. The movable mold moves to the left again under the push of the cylinder and presses against the fixed body to pressurize the movable cavity and the fixed cavity. The molded plastic is held by the pressure-control ring and shaken off due to the return action of the pressure-control spring.

[0010] In the prior art, when performing thermosetting plastic injection molding, the pressure in the mold cavity is often increased by increasing the feed pressure, thereby ensuring the tight combination of the plastic in the mold cavity. However, there are obvious problems when injecting thermosetting plastics with poor fluidity in this way: on the one hand, the thermosetting plastics with poor fluidity also have a poor pressure transmission effect, so the fluid plastic close to the feed port will be subjected to greater pressure, and the feed port area is limited, which makes the pressure transmission effect in the mold cavity worse, thereby making the pressure distribution in the mold cavity more uneven; on the other hand, the feed channel is connected to the extruder, and the increase in feed pressure means that the pressure of the fluid plastic in the extruder pipeline increases synchronously, which will make the fluid plastic in the extruder more viscous, and then lead to the need for greater feed pressure in the subsequent process, which will not only increase energy consumption, but also accelerate the loss of related equipment (such as the screw mechanism in the extruder), and shorten the service life of the equipment. The above phenomenon will be more obvious when injecting thermosetting plastics with poor fluidity;

[0011] Preferably, the feed channel includes a feed section and a guide section from left to right, the feed section is configured as a stepped hole structure, the guide section is configured as a tapered hole structure, and the small diameter end of the tapered hole is on the left, the flow control rod includes a rod body and a rod head from left to right, and the rod body is inserted into the feed section;

[0012] Through the above scheme, there is no need to use the feed pressure to increase the pressure in the fixed cavity and the dynamic cavity. Instead, the flow control rod, the feed channel and the flow control spring interact with each other to produce a function similar to a one-way valve. When the one-way valve is opened, the feed channel can feed normally; when the one-way valve is closed, the fixed cavity is isolated from the feed channel, and the pressurization of the fixed cavity and the dynamic cavity will not affect the feed channel and the fluid plastic in the extruder.

[0013] Compared with the prior art which increases the pressure in the dynamic cavity and the fixed cavity by increasing the feed pressure, the present solution has the following advantages: in terms of longitudinal cross-sectional area, the dynamic mold is obviously larger than the feed channel, and the large longitudinal cross-sectional area means that the pressure can be applied more evenly to the plastics in the given cavity and the dynamic cavity, so that the concentration of the plastics everywhere is uniform, and thus the strength of the molded product is consistent everywhere. Especially for thermosetting plastics with poor fluidity during injection molding, uniform force application can significantly improve the quality of the molded product. Moreover, in this process, through the movement of the dynamic mold, the plastic away from the feed channel will be squeezed first and flow toward the feed channel, thereby forming a complementary relationship with the feeding.

[0014] The taper of the guide section cannot be too large. First, it is to ensure that the thickness of the fluid plastic in each part of the guide section is as uniform as possible, so that there will be no obvious temperature difference in the fluid plastic of the guide section during the heating and curing cycle of the injection mold, thereby ensuring the consistency of the plastic fluidity; second, it is to avoid the diameter of the guide section changing too quickly, thereby causing the pressure of the fluid plastic in the guide section to decrease rapidly, resulting in a decrease in the pressure on the rod head, a shortened right travel distance, and a slowdown in the speed of the plastic flowing to the fixed cavity, resulting in a decrease in production speed;

[0015] Preferably, the rod head is configured as a combination of two sections of truncated cones, and the taper of the left truncated cone of the rod head is greater than the taper of the right truncated cone of the rod head, the taper of the right truncated cone of the rod head is equal to the taper of the guide section, and the right end face diameter of the right truncated cone of the rod head is equal to the major diameter of the guide section, and the flow control spring is installed on the rod body, and the flow control spring is located between the rod head and the stepped hole wall of the feed section;

[0016] The small taper of the guide section will weaken the guiding effect of the guide section on the rod head. Therefore, this scheme sets the rod head as a combination of frustums at both ends. The frustum with a larger taper on the left side can not only make up for the guiding effect of the guide section, but also use its own small diameter to form a larger gap with the guide section when the rod head moves to the right, thereby facilitating the flow of plastic to the fixed mold, thereby speeding up production.

[0017] In the prior art, the inside of the extruder is often directly connected to the inside of the injection mold, and the extension of the heating cycle during the injection molding process helps to improve the quality of the molded product. It is usually set at about 60S. Therefore, during the heating cycle, the fluid plastic at the outlet of the extruder will be affected by the high temperature of the mold cavity for a long time, and has a tendency to solidify or solidifies, thereby reducing its own fluidity, thereby weakening its ability to combine with other plastics during mold molding, and affecting the local quality of the molded product;

[0018] Preferably, the rod head is made of a heat-insulating material, and the flow-control spring is made of a high-temperature-resistant material.

[0019] Through the above scheme, during the heating cycle, the rod head made of insulating material is used to separate the feed channel and the fixed cavity to avoid heat exchange between the plastics in the feed channel and the fixed cavity, thereby ensuring the consistency of the fluidity of the plastic in the feed channel and avoiding the impact on the heating and curing process of the plastic in the fixed mold, thereby ensuring the quality of the molded product.

[0020] The injection mold has a long heating cycle, and the fluid plastic in the feed channel should be heated to keep it warm, thereby ensuring the fluidity of the fluid plastic and the quality of the molded product. It can be seen that there are many ways to keep it warm, such as setting an insulation layer on the fixed body, and designing the flow control spring as an electric heating wire. Compared with this solution, the above solution 1 is a method that is easy to implement, but correspondingly, as a passive insulation method (similar to a thermos bottle), its effect is limited. The above solution 2 can achieve active insulation through electric heating, but the temperature of electric heating is generally high, and the heating temperature is not easy to control. Excessive heating will cause the thermosetting plastic to solidify or degrade;

[0021] Preferably, the stator is provided with a liquid inlet and a liquid outlet along its radial direction, and the liquid inlet is below the liquid outlet, the feed section is provided with an inner tube, the inner tube is interference fit with the feed section, a thread groove is provided on the outer circumferential surface of the inner tube, the thread groove is a double-line thread structure, and the double-line threads of the thread groove are respectively connected to the liquid inlet and the liquid outlet.

[0022] Through the above scheme, on the one hand, with the help of the thread groove and the flow control spring, the fluid plastic in the feed channel is heated by liquid circulation during the heating cycle to maintain the fluidity of the plastic, thereby ensuring the quality of the molded product; on the other hand, through the interference fit between the inner tube and the feed section, it is ensured that the liquid circulating in the thread groove will not be immersed in the plastic to ensure the purity of the plastic, and through the setting of the thread groove, the area of ​​the outer circumference of the inner tube is reduced, thereby making the interference installation of the inner tube and the feed section easier.

[0023] Preferably, a plurality of support blocks are provided on the inner circumferential surface of the inner tube, the plurality of support blocks are arrayed along the axial direction and the circumferential direction of the inner tube, and the radial surfaces of the support blocks are inclined surfaces.

[0024] Through the above scheme, while the support blocks are used to form circumferential positioning for the rod body, the influence on the flow of plastic in the inner tube is avoided by means of the dispersed arrangement of multiple support blocks on the inner circumferential surface of the inner tube. Furthermore, the radial surface of the support block is set as an inclined surface to guide the flowing plastic passing through the support block, thereby reducing the resistance to the flow of plastic.

[0025] Preferably, the flow control spring includes a liquid inlet spring and a liquid outlet spring, the pitch of the liquid inlet spring and the liquid outlet spring are consistent with the number of turns, the interior of the liquid inlet spring and the liquid outlet spring is hollow, the left ends of the liquid inlet spring and the liquid outlet spring are respectively connected to the double-line thread of the thread groove, and an annular groove is provided inside the rod head, and the annular groove is connected to the left ends of the liquid inlet spring and the liquid outlet spring.

[0026] Through the above scheme, the liquid inlet spring and the liquid outlet spring not only have the function of adjusting the flow control rod, but also can complete the circulation of the heated liquid through the hollow interior to keep the fluid plastic in the feed section warm, thereby ensuring the fluidity of the plastic, thereby ensuring the quality of the molded product, and the two ends of the liquid inlet spring and the liquid outlet spring are respectively connected to the side wall of the inner tube and the side wall of the rod head, and then through their own deformation, when the rod head moves to the right and resets, they can completely heat the guide section, and when the rod head resets, the liquid inlet spring and the liquid outlet spring contract, thereby concentrating the heat they emit inside the feed channel, thereby better keeping the fluid plastic in the heating cycle warm, to ensure the fluidity of the plastic in the feed channel when it is injected into the fixed cavity, thereby ensuring the quality of the molded product.

[0027] Preferably, a slide groove is provided on the right end face of the fixed body, a slider is provided on the circumferential surface of the pressure control ring, the thickness of the slider is less than the thickness of the pressure control ring, a retaining ring is arranged on the right notch of the slide groove, and gaps are provided between the slider and the retaining ring and the radial outer wall of the slide groove, so that the interior of the slide groove is always connected to the outside world, thereby avoiding compression of the gas inside the slide groove, which leads to an increase in the resistance of the slider to the left.

[0028] Through the above scheme, the circumferential positioning of the pressure control ring is achieved with the help of the slider and the slide groove, thereby avoiding the friction between the pressure control ring and the fixed body, thereby ensuring that the contact between the pressure control ring and the fixed body is always close, and the pressure control ring is axially limited by the retaining ring, so that the pressure control ring always slides inside the fixed body, and the sliding of the pressure control ring is used to buffer the movable mold, thereby avoiding the collision between the movable mold and the fixed mold, thereby improving the service life of the injection mold.

[0029] In the prior art, an ejector mechanism, such as an ejector rod, is often provided on the movable mold to eject the product when the movable mold drives the molded product to move. However, the provision of the ejector rod requires a hole to be opened on the surface of the mold cavity, which results in an annular convex mark on the surface of the molded product, which needs to be polished by hand or equipment.

[0030] Preferably, the inner ring of the pressure control ring is provided with a filling ring, the filling ring is arranged as an inner conical structure, and the filling ring is made of a flexible high temperature resistant material.

[0031] Through the above scheme, on the one hand, the filling ring can make the pressure control ring contact more closely with the fixed body to avoid the plastic leakage of the fixed cavity and the movable cavity, thereby ensuring the high pressure in the fixed cavity and the movable cavity, thereby ensuring the quality of the molded product; on the other hand, after the heating cycle is over, the movable mold drives the molded product to the right, and the pressure control ring is reset under the action of the pressure control spring. During the resetting process of the pressure control ring, the filling ring will clamp the side of the molded product, and the slider will vibrate after contacting the retaining ring, thereby shaking off the molded product clamped by the filling ring. In this way, the ejection mechanism is omitted, and the molded product does not need to be polished with convex marks.

[0032] Preferably, an air channel is arranged on the right side surface of the pressure control ring, and a plurality of the air channels penetrate the pressure control ring and the filling ring.

[0033] Through the above scheme, the air channel is set on the right side of the pressure control ring and the filling ring. When the movable mold is pre-pressed, the gas in the fixed cavity and the movable cavity can be discharged from the air channel. When the movable mold is pressed, the movable mold and the fixed mold are tightly attached and the air channel is blocked. The plastic under high pressure cannot be discharged from the air channel to the outside.

[0034] In order to inject products of different strengths, the pressure in the mold should be adjustable. The specific method is to adjust the distance of the movable mold pre-pressure, which requires the control of the stroke of the cylinder. It can be seen that there are many ways to control the stroke of the cylinder, such as using PLC or single-chip microcomputer to control the solenoid valve, and then control the fixed-point start and stop of the cylinder. Compared with this solution, PLC has complete functions but higher costs, and single-chip microcomputer has lower costs but longer design cycles;

[0035] Preferably, the cylinder is a double-acting cylinder, and the control mode of the cylinder is set to table control.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention opens or closes the cavity of the injection mold by opening and closing the flow control rod and the feed channel, and then the mold cavity is in a closed state under the premise of ensuring that the fluid plastic enters the mold cavity normally, so that the large area of ​​the fluid plastic is pressed by the dynamic mold cavity wall, the pressure of the mold cavity is increased to make the fluid plastic more tightly combined, and the fluid plastic is evenly pressurized at various locations, so that the degree of combination of the fluid plastic at various locations is consistent, thereby ensuring the overall quality of the molded product.

[0038] 2. The present invention controls the flow control rod through a flow control spring. When there is or is not feed pressure, the flow control spring is pulled to open or reset the closed injection mold cavity. At the same time, the hollow setting of the flow control spring allows liquid heat circulation to heat and keep the fluidized plastic in the feed channel, thereby ensuring the fluidity of the fluidized plastic in the feed channel, and further ensuring that the fluidity of the fluidized plastic at various locations is consistent during re-injection, thereby improving the quality of the molded product.

[0039] 3. The present invention, through the setting of the pressure control ring, always presses the movable mold during the pre-pressing and pressing process to cooperate with the flow control rod to open or close the mold cavity, and can also buffer the collision between the movable mold and the fixed mold to extend the service life of the injection mold. The pressure control ring can not only seal the mold cavity more tightly through the filling ring on its inner circle, but also replace the original ejection mechanism of the injection mold to make the surface of the molded product smoother. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the overall isometric structure of the present invention;

[0041] Figure 2 For the present invention Figure 1 The enlarged schematic diagram of part A in the middle;

[0042] Figure 3 It is an exploded schematic diagram of the internal structure of the fixed mold of the present invention;

[0043] Figure 4 It is a schematic diagram of the inner tube structure of the present invention;

[0044] Figure 5 It is a schematic diagram of the structure of the pressure control ring of the present invention;

[0045] Figure 6 It is a schematic diagram of the pre-pressing and feeding state of the present invention;

[0046] Figure 7 It is a schematic diagram of the compaction and forming state of the present invention;

[0047] Figure 8 It is a schematic diagram of the demoulding state of the present invention.

[0048] In the figure: 1. movable mold; 11. movable cavity; 2. fixed mold; 21. fixed body; 211. slide groove; 22. feed channel; 221. feed section; 2211. inner tube; 22111. threaded groove; 22112. support block; 222. guide section; 23. fixed cavity; 24. liquid inlet channel; 25. liquid outlet channel; 3. pressure control ring; 31. slider; 32. air channel; 4. pressure control spring; 5. flow control spring; 51. liquid inlet spring; 52. liquid outlet spring; 6. flow control rod; 61. rod body; 62. rod head; 621. ring groove; 7. cylinder; 8. retaining ring; 9. filling ring. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] See also Figures 1 to 8 The present invention provides an injection mold for thermosetting plastic molding, and the technical solution is as follows:

[0051] An injection mold for thermosetting plastic molding, comprising a movable mold 1, a movable cavity 11 is arranged in the movable mold 1, and also comprising a fixed mold 2, a pressure control ring 3, a pressure control spring 4, a flow control spring 5, a flow control rod 6 and a cylinder 7, the fixed mold 2 comprises a fixed body 21, a feed channel 22 and a fixed cavity 23, the fixed body 21 is arranged on the left side of the movable mold 1, the feed channel 22 and the fixed cavity 23 are arranged inside the fixed body 21 from left to right, the pressure control ring 3 is installed on the right end surface of the fixed body 21, the pressure control spring 4 is arranged between the pressure control ring 3 and the fixed body 21, the flow control rod 6 is inserted into the feed channel 22, the flow control spring 5 is installed on the flow control rod 6, and the cylinder 7 is arranged on the right side of the movable mold 1;

[0052] The pressure-control ring 3 is pre-pressed by the movable mold 1 to merge the movable cavity 11 and the fixed cavity 23. The fluid plastic in the feed channel 22 pushes the flow-control rod 6 due to the feed pressure and flows to and gradually fills the fixed cavity 23 and the movable cavity 11. The flow-control rod 6 that loses the feed pressure moves to the left due to the return force of the flow-control spring 5 and separates the feed channel 22 and the fixed cavity 23. The movable mold 1 moves to the left again due to the push of the cylinder 7 and presses against the fixed body 21 to pressurize the movable cavity 11 and the fixed cavity 23. The molded plastic is clamped by the pressure-control ring 3 and shaken off due to the return action of the pressure-control spring 4.

[0053] As an embodiment of the present invention, refer to Figure 1 and Figure 2, the feed channel 22 includes a feed section 221 and a guide section 222 from left to right, the feed section 221 is set to a stepped hole structure, the guide section 222 is set to a tapered hole structure, and the small diameter end of the tapered hole is on the left, the flow control rod 6 includes a rod body 61 and a rod head 62 from left to right, the rod body 61 is inserted into the feed section 221, the rod head 62 is set to a combination of two sections of frustum, and the taper of the left frustum of the rod head 62 is greater than the taper of the right frustum of the rod head 62, the taper of the right frustum of the rod head 62 is equal to the taper of the guide section 222, and the right end face diameter of the right frustum of the rod head 62 is equal to the major diameter of the guide section 222, the flow control spring 5 is installed on the rod body 61, and the flow control spring 5 is located between the rod head 62 and the stepped hole wall of the feed section 221, the flow control spring 5 is made of high temperature resistant material (such as GH series high temperature alloy steel), the rod head 62 is made of insulation material, the insulation material The weldability of the rod head 62 is generally poor, and the rod head 62 needs to be welded with the flow control spring 5, so the right end of the rod head 62 (i.e., the part close to the fixed cavity 23) is made of a heat-insulating material (such as aluminum silicate fiber), and the left end of the rod head 62 is made of steel with good weldability. The inside of the rod head 62 is provided with an annular groove 621, so the production steps of the flow control rod 6 are as follows: 1. First, the right end (i.e., the heat insulation) of the rod head 62, the left end (i.e., the part with good weldability) of the rod head 62 and the rod body 61 are manufactured separately. It should be noted that half of the annular groove 621 is opened on the left end surface of the left end of the rod head 62, and the right end of the rod body 61 is provided with a part of the flange, and the right end surface of the flange is provided with the other half of the annular groove 621; 2. When installing, first weld the flange of the rod body 61 to the left end of the rod head 62, pay attention to aligning the annular groove 621 during welding, and then embed the right end of the rod head 62 on the left end of the rod head 62;

[0054] The feed channel 22 acts as a "valve body" and the flow control rod 6 acts as a "valve core", which has the following three processes: 1. During the heating cycle (i.e., the feed channel 22 is not feeding), the rod head 62 of the flow control rod 6 is pressed against the guide section 222 of the feed channel 22 by the reset tension of the flow control spring 5; 2. During the feeding process, the rod head 62 moves right due to the feeding pressure in the feed channel 22, so that the fluid plastic in the feed channel 22 is injected into the fixed cavity 23 and the dynamic cavity 11; 3. After the feeding is completed, the dynamic mold 1 continues to move left, so that the fluid plastic in the dynamic cavity 11 flows into the fixed cavity 23, and at this time, the rod head 62 is already pressed against the guide section 222 under the action of the flow control spring 5, that is, the passage of the fluid plastic in the fixed cavity 23 to the feed section 221 is blocked, so that the pressure in the dynamic cavity 11 and the fixed cavity 23 gradually increases as the dynamic mold 1 moves left again.

[0055] As an embodiment of the present invention, refer to Figure 3 and Figure 4The fixed body 21 is provided with a liquid inlet 24 and a liquid outlet 25 along its radial direction, and the liquid inlet 24 is below the liquid outlet 25. The feed section 221 is provided with an inner tube 2211, and the inner tube 2211 is interference fit with the feed section 221. A thread groove 22111 is provided on the outer circumference of the inner tube 2211. The thread groove 22111 is a double-thread structure, and the double-thread of the thread groove 22111 is respectively connected with the liquid inlet 24 and the liquid outlet 25. A plurality of support blocks 22112 are provided on the inner circumference of the inner tube 2211. The plurality of support blocks 22112 are arrayed along the axial direction and circumferential direction of the inner tube 2211, and the radial surface of the support block 22112 is an inclined surface.

[0056] The inner tube 2211 is installed inside the feed section 221 by cold assembly: before assembly, the welded body of the inner tube 2211, the flow control spring 5 and the flow control rod 6 is first placed in liquid nitrogen, and then the inner tube 2211 is inserted into the feed section 221 from the guide section 222. During installation, pay attention to aligning the two notches of the thread groove 22111 with the liquid inlet channel 24 and the liquid outlet channel 25; for plastics with different injection molding temperatures, the boiling point of the liquid can be adjusted by selection or proportioning, so as to avoid excessive heating of the plastic to prevent the plastic from solidifying or degrading; when processing the thread groove 22111, first use a lathe to turn out a thread, and then rotate the inner tube 2211 on the lathe chuck 180°. Note that the depth of the inner tube 2211 inserted into the chuck cannot be changed, and then repeat the lathe turning steps.

[0057] As an embodiment of the present invention, refer to Figure 3 The flow control spring 5 includes a liquid inlet spring 51 and a liquid outlet spring 52. The pitch of the liquid inlet spring 51 and the liquid outlet spring 52 is consistent with the number of turns. The inside of the liquid inlet spring 51 and the liquid outlet spring 52 is hollow. The left ends of the liquid inlet spring 51 and the liquid outlet spring 52 are respectively connected to the double-line thread of the thread groove 22111, and the annular groove 621 is connected to the left ends of the liquid inlet spring 51 and the liquid outlet spring 52;

[0058] The liquid inlet spring 51 and the liquid outlet spring 52 are made of the same material and the same process. When installing, the liquid inlet spring 51 and the liquid outlet spring 52 are first welded to the rod head 62, so that the liquid inlet spring 51 and the liquid outlet spring 52 are connected through the annular groove 621 inside the rod head 62, and then the left ports of the liquid inlet spring 51 and the liquid outlet spring 52 are respectively aligned with the outlet of the thread groove 22111, and the left end faces of the liquid inlet spring 51 and the liquid outlet spring 52 are welded to the right end face of the inner tube 2211; during the liquid circulation process, The heated liquid is pumped out by a water pump, first passing through the liquid inlet 24, then entering the threaded groove 22111, and then passing through the liquid inlet spring 51, the annular groove 621, and the liquid outlet spring 52 in sequence, and finally discharged to the liquid outlet 25 through the threaded groove 22111. The liquid discharged from the liquid outlet 25 is heated again and then pumped to the liquid inlet 24 again by the water pump, and so on. The heating of the injection mold usually adopts pipeline circulation heating. Therefore, the liquid circulation process can be achieved with the help of the heating device of the injection mold.

[0059] As an embodiment of the present invention, refer to Figure 1 , Figure 3 and Figure 5 There are slide grooves 211 in a circular array on the right end face of the fixed body 21, and sliders 31 are arrayed on the circumferential surface of the pressure control ring 3. The thickness of the slider 31 is less than that of the pressure control ring 3. A retaining ring 8 is arranged on the right notch of the slide groove 211. There are gaps between the slider 31 and the retaining ring 8 and the radial outer wall of the slide groove 211. The gap between the slider 31 and the slide groove 211 is obtained by reducing the radial length of the slider 31 along the pressure control ring 3, and the gap between the slider 31 and the retaining ring 8 is achieved by reducing the outer diameter of the retaining ring 8.

[0060] As an embodiment of the present invention, refer to Figure 3 The inner ring of the pressure control ring 3 is provided with a filling ring 9, which is arranged as an inner conical structure and is made of a flexible high temperature resistant material (such as fluororubber, silicone rubber, etc.). In order to enhance the demolding effect of the filling ring 9, the thickness of the pressure control ring 3 and the filling ring 9 can be increased so that the molded product can be more stably separated from the movable mold 1.

[0061] As an embodiment of the present invention, refer to Figure 3 There are air channels 32 in a circular array on the right side of the pressure control ring 3. Multiple air channels 32 penetrate the pressure control ring 3 and the filling ring 9. The depth of the air channels 32 depends on the injection molding material and the injection molding shape in actual production.

[0062] As an embodiment of the present invention, refer to Figure 1 Cylinder 7 is a double-acting cylinder, and the control mode of cylinder 7 is set to table control. The table controller adopts 24V DC power supply to drive the 24V solenoid valve, and uses its own timing function to control the fixed-point start and stop of cylinder 7.

[0063] Working principle: The prior art increases the pressure in the injection mold cavity by increasing the feed pressure to improve the quality of the molded product. However, the area of ​​the feed port is limited, and the strong pressure at the feed port is not transmitted well in thermosetting plastics with poor fluidity. Therefore, it is difficult for the fluid plastic to fill the mold cavity, and the fluid plastic in different parts of the cavity is under different pressures. Correspondingly, the bonding force is also different, which makes the performance of the molded product different in different parts. Compared with the prior art, the most essential difference of the present invention is that it increases the force application area of ​​the fluid plastic, so that the fluid plastic can transfer the pressure more evenly during the pressure process. The specific method is to gradually reduce the volume of the injection mold cavity by pressing the movable mold 1 to increase the pressure inside the cavity, and apply force to the plastic through the large area of ​​the cavity wall of the movable mold 1.

[0064] Specifically, this solution includes five steps: pre-pressing, feeding, compacting, molding and demoulding; Figure 6During pre-pressing, the movable mold 1 moves to the left by a set value, so that its left end face is pressed against the right end face of the pressure control ring 3, so as to form a radial closure for the fixed cavity 23 and the movable cavity 11; then, the material is fed through the feed channel 22, so that the fluid plastic fills the fixed cavity 23 and the movable cavity 11; then, the pressing step is entered, and the movable mold 1 is pushed by the cylinder 7 to move to the left again, and its left end face is pressed against the right end face of the fixed mold 2, so that the fixed cavity 23 and the movable cavity 11 are further combined, thereby reducing the total volume of the fixed cavity 23 and the movable cavity 11, thereby increasing the pressure in the fixed cavity 23 and the movable cavity 11;

[0065] refer to Figure 7 In the pressing process, in order to prevent the fluid plastic in the fixed cavity 23 and the dynamic cavity 11 from flowing back along the feed channel 22, a flow control rod 6 is arranged in the feed channel 22, and the fixed cavity 23 is closed by the fitting of the rod head 62 of the flow control rod 6 and the feed channel 22. Specifically, the flow control spring 5 is in a naturally stretched state in the feed channel 22. During feeding, under the feeding pressure of the feeding device, the rod head 62 moves to the right to connect the fixed cavity 23 with the feed channel 22, so that the fluid plastic enters the fixed cavity 23 and the dynamic cavity 11. After the feeding is completed, the rod head 62 that loses the feeding pressure is reset by the flow control spring 5 and fits the feed channel 22, thereby closing the fixed cavity 23, thereby ensuring that the fixed cavity 23 and the dynamic cavity 11 are in a completely closed state during the pressing process;

[0066] During molding, the thermosetting plastics in the fixed cavity 23 and the moving cavity 11 are heated to undergo a cross-linking and curing reaction. The molding process takes a certain amount of time. In order to prevent the fluid plastic in the feed channel 22 from cooling down during the molding process, thereby reducing its own fluidity and affecting the quality of subsequent molded products, the fluid plastic in the feed channel 22 is heated and insulated by means of the setting of the flow control spring 5. Specifically, a threaded groove 22111 is provided on the outer peripheral surface of the inner tube 2211. The flow control spring 5 includes a feed channel 22111 and a flow control spring 5. The liquid spring 51 and the liquid outlet spring 52 are hollow inside. The left ends of the liquid inlet spring 51 and the liquid outlet spring 52 are connected to the thread groove 22111 of the inner tube 2211, and the right ends are connected to the rod head 62. The heated liquid enters the thread groove 22111, the liquid inlet spring 51, the ring groove 621, and the liquid outlet spring 52 from the liquid inlet channel 24 in sequence, and then passes through the thread groove 22111 and is discharged from the liquid outlet channel 25 to complete the thermal cycle heating.

[0067] refer to Figure 8After the plastic is molded, the movable mold 1 moves rightward to make the molded product fall off to complete the whole process of injection molding; in the prior art, a special ejection mechanism, such as an ejector rod, is often provided for demoulding. However, such an ejection mechanism will leave convex marks on the surface of the molded product, which needs to be polished smooth later. In order to avoid the above phenomenon, the present invention cancels the use of the ejection mechanism and uses the filling ring 9 on the pressure control ring 3 to produce a similar effect and has a better effect. Specifically, the filling ring 9 is arranged on the inner ring of the pressure control ring 3, and the filling ring 9 is set to an inner cone structure. When the movable mold 1 moves rightward for demoulding, the molded product has a tendency to move with the movable mold 1, but the pressure control ring 3 reset under the action of the pressure control spring 4 will clamp the molded product with the help of its own filling ring 9, so that the molded product falls off the movable mold 1, and the slider 31 of the pressure control ring 3 hits the retaining ring 8 under the reset action, so that the pressure control ring 3 vibrates, and then shakes off the clamped molded product, thereby completing the demoulding and making the surface of the molded product smooth.

[0068] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An injection mold for thermosetting plastic molding, comprising a movable mold (1), wherein a movable cavity (11) is provided in the movable mold (1), characterized in that: It also comprises a fixed mold (2), a pressure control ring (3), a pressure control spring (4), a flow control spring (5), a flow control rod (6) and a cylinder (7); the fixed mold (2) comprises a fixed body (21), a feed channel (22) and a fixed cavity (23); the fixed body (21) is arranged on the left side of the movable mold (1); the feed channel (22) and the fixed cavity (23) are arranged inside the fixed body (21) from left to right; the pressure control ring (3) is installed on the right end surface of the fixed body (21); the pressure control spring (4) is arranged between the pressure control ring (3) and the fixed body (21); the flow control rod (6) is inserted into the feed channel (22); the flow control spring (5) is installed on the flow control rod (6); and the cylinder (7) is arranged on the right side of the movable mold (1); The pressure control ring (3) is pre-pressed by the movable mold (1) to merge the movable cavity (11) and the fixed cavity (23). The fluid plastic in the feed channel (22) is pushed by the feed pressure to push the flow control rod (6) and flow to and gradually fill the fixed cavity (23) and the movable cavity (11). The flow control rod (6) that loses the feed pressure is reset by the control flow spring (5) to move to the left and cut off the feed channel (22) and the fixed cavity (23). The movable mold (1) is pushed by the cylinder (7) to move to the left again and press against the fixed body (21) to pressurize the movable cavity (11) and the fixed cavity (23). The molded plastic is clamped by the pressure control ring (3) and shaken off by the reset action of the pressure control spring (4).

2. The injection mold for thermosetting plastic molding according to claim 1, characterized in that: The feed channel (22) comprises a feed section (221) and a guide section (222) from left to right, the feed section (221) is configured as a stepped hole structure, the guide section (222) is configured as a conical hole structure, the flow control rod (6) comprises a rod body (61) and a rod head (62) from left to right, the rod body (61) is inserted into the feed section (221), the rod head (62) is configured as a combination of two sections of truncated cones, the taper of the left truncated cone of the rod head (62) is greater than the taper of the right truncated cone of the rod head (62), the taper of the right truncated cone of the rod head (62) is equal to the taper of the guide section (222), and the right end face diameter of the right truncated cone of the rod head (62) is equal to the major diameter of the guide section (222), the flow control spring (5) is mounted on the rod body (61), and the flow control spring (5) is located between the rod head (62) and the stepped hole wall of the feed section (221).

3. The injection mold for thermosetting plastic molding according to claim 2, characterized in that: The rod head (62) is made of a heat-insulating material, and the flow-controlling spring (5) is made of a high-temperature-resistant material.

4. The injection mold for thermosetting plastic molding according to claim 2, characterized in that: The fixed body (21) is provided with a liquid inlet channel (24) and a liquid outlet channel (25) along its radial direction, and the liquid inlet channel (24) is below the liquid outlet channel (25); the feed section (221) is provided with an inner tube (2211), the inner tube (2211) is interference fit with the feed section (221), and a thread groove (22111) is provided on the outer peripheral surface of the inner tube (2211), the thread groove (22111) is a double-thread structure, and the double-thread threads of the thread groove (22111) are respectively connected to the liquid inlet channel (24) and the liquid outlet channel (25).

5. The injection mold for thermosetting plastic molding according to claim 4, characterized in that: A plurality of support blocks (22112) are arranged on the inner circumferential surface of the inner tube (2211), and the plurality of support blocks (22112) are arranged in an axial and circumferential array along the inner tube (2211), and the radial surfaces of the support blocks (22112) are inclined surfaces.

6. The injection mold for thermosetting plastic molding according to claim 4, characterized in that: The flow control spring (5) comprises a liquid inlet spring (51) and a liquid outlet spring (52), the pitch of the liquid inlet spring (51) and the number of turns of the liquid outlet spring (52) being consistent, the interior of the liquid inlet spring (51) and the liquid outlet spring (52) being hollow, the left ends of the liquid inlet spring (51) and the liquid outlet spring (52) being respectively connected to the double-threaded thread of the thread groove (22111), the interior of the rod head (62) being provided with an annular groove (621), the annular groove (621) being connected to the left ends of the liquid inlet spring (51) and the liquid outlet spring (52).

7. The injection mold for thermosetting plastic molding according to claim 1, characterized in that: A slide groove (211) is provided on the right end face of the fixed body (21), a slider (31) is provided on the circumferential surface of the pressure control ring (3), the thickness of the slider (31) is less than the thickness of the pressure control ring (3), a retaining ring (8) is arranged on the right notch of the slide groove (211), and a gap is provided between the slider (31) and the retaining ring (8) and the radial outer wall of the slide groove (211).

8. The injection mold for thermosetting plastic molding according to claim 7, characterized in that: The inner ring of the pressure control ring (3) is provided with a filling ring (9), the filling ring (9) is arranged as an inner conical structure, and the filling ring (9) is made of a flexible high-temperature resistant material.

9. The injection mold for thermosetting plastic molding according to claim 8, characterized in that: An air channel (32) is arranged on the right side surface of the pressure control ring (3), and a plurality of the air channels (32) penetrate the pressure control ring (3) and the filling ring (9).

10. The injection mold for thermosetting plastic molding according to claim 1, characterized in that: The cylinder (7) is a double-acting cylinder, and the control mode of the cylinder (7) is set to be meter control.

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