Impact-resistant PVC pipe injection molding device and method

Abstract

The invention relates to the technical field of PVC pipe injection molding, and particularly discloses an anti-impact PVC pipe injection molding device and method.The anti-impact PVC pipe injection molding device comprises a rotary table, a plurality of lower molds are arranged on the rotary table, an upper mold is arranged over one of the lower molds, each lower mold comprises a mold core and a mold cavity, and an injection molding gap is formed between the mold core and the mold cavity; the water guide disc comprises a disc body and a sealing ring rotationally connected to the outer wall of the disc body in a sealed mode, the disc body communicates with a water guide pipeline, and a plurality of water guide cavities communicating with the interior of the disc body are formed in the side wall of the sealing ring; heat dissipation water paths are arranged in the mold core and the mold cavity, and water pipes are communicated between the heat dissipation water paths and the water guide cavity; according to the heat dissipation water channel mold, the situation that the temperature rise of a single heat dissipation water channel is too high can be avoided, then the situation that an extreme low heat conduction area and an extreme high heat conduction area are formed in the mold is avoided, the impact resistance of PVC pipes formed in the same batch is improved, the overall product quality consistency is improved, and the rejection rate is reduced.

Description

Technical Field

[0001] This application relates to the field of PVC pipe injection molding technology, and specifically discloses an impact-resistant PVC pipe injection molding apparatus and method. Background Technology

[0002] In the injection molding process of PVC pipes, the stability of the mold temperature is one of the key process parameters affecting the final performance of the product. Especially for heat-sensitive materials such as polyvinyl chloride (PVC), the temperature uniformity of different areas of the mold directly affects the cooling rate, crystal morphology, and internal stress distribution of the plastic melt, which in turn has a decisive impact on the impact strength, dimensional accuracy, and surface quality of the molded pipe. If the mold temperature is not uniformly controlled, it can easily lead to defects such as localized embrittlement, significant differences in shrinkage, or flow marks, severely reducing the mechanical properties and service life of the pipe.

[0003] Currently, rotary table vertical injection molding machines are widely used in the multi-cavity synchronous molding of PVC pipes. These machines typically feature a multi-station rotary platform, enabling the sequential completion of mold closing, injection, cooling, mold opening, and part removal within a single cycle, significantly improving production efficiency and making them suitable for mass production of pipes with uniform specifications. However, due to the limitations of the rotary table structure and continuous rotation, the cooling water channels inside the injection mold are often difficult to arrange in a parallel configuration with independent interconnections and temperature control. To accommodate the rotary table's rotation and limited space, the cooling water channels are mostly forced to adopt a series connection, meaning the cooling medium flows sequentially through multiple mold cavities or different sections of the mold.

[0004] This series-connected water channel arrangement has significant drawbacks: the cooling medium continuously absorbs heat during its flow, and its temperature gradually increases as it flows through subsequent mold cavities or areas, resulting in a significant temperature difference between the water channel inlet and outlet. This leads to a decrease in overall cooling efficiency and uneven temperature distribution. Furthermore, due to the long water channel path and fixed flow direction, the heat dissipation conditions vary at different physical locations, easily forming low-thermal-conductivity and high-thermal-conductivity zones inside the mold. Insufficient cooling in the low-thermal-conductivity zones causes slow cooling of the PVC melt in the corresponding areas, potentially leading to uneven product shrinkage or decreased strength; conversely, excessively rapid cooling in the high-thermal-conductivity zones may cause premature solidification of the melt, affecting filling integrity or generating high internal stress.

[0005] Uneven heat exchange makes it difficult to control the mold temperature field stably, which directly leads to differences in the impact resistance of PVC pipes molded in the same batch, poor overall product quality consistency, and increased scrap rate. Therefore, in view of this, the present invention provides an impact-resistant PVC pipe injection molding apparatus and method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to solve the problem that in the traditional PVC pipe injection molding process, low thermal conductivity areas and high thermal conductivity areas are easily formed inside the mold, resulting in poor product quality consistency.

[0007] To achieve the above objectives, the basic solution of the present invention provides an impact-resistant PVC pipe injection molding apparatus, comprising: A turntable with several lower molds on it, one of which has an upper mold directly above it. The lower mold includes a core and a cavity, and an injection gap is formed between the core and the cavity. A water guide plate includes a plate body and a sealing ring that is rotatably sealed to the outer wall of the plate body. The plate body is connected to a water guide pipe, and the side wall of the sealing ring is provided with several water guide cavities that communicate with the interior of the plate body. The core and cavity are equipped with heat dissipation water channels, and water pipes are connected between the heat dissipation water channels and the water guiding cavity. The water guide plate consists of two parts, each connected to one end of the heat dissipation water channel. The principle and effect of this basic scheme are as follows: Compared with the prior art, the present invention utilizes the water guide plate to ensure that the heat dissipation water channels in each lower mold can maintain a parallel connection in a compact environment, and can maintain a sealed and stable connection during the rotation of the lower mold. This avoids excessive temperature rise in a single heat dissipation water channel, thereby preventing the formation of extreme low thermal conductivity and high thermal conductivity areas in the mold. As a result, the impact resistance of PVC pipes molded in the same batch is improved, the overall product quality consistency is improved, and the scrap rate is reduced.

[0008] Furthermore, the lower mold also includes connecting pillars symmetrically arranged between the core and the cavity, and the cooling water channel passes through the cavity, the connecting pillars, and the core. This creates a cooling water channel for dissipating heat from the cavity and core within the confined space of the lower mold.

[0009] Furthermore, it also includes top-out mechanisms, including: The ejector ring is adapted to the injection gap, and each ejector ring is symmetrically connected with a support rod, the bottom of which protrudes through the lower mold. The connecting plate connects to the ends of each support rod in the same lower mold. The pusher component pushes the connecting plate to move vertically.

[0010] During the injection molding process, the ejector ring, as the bottom end of the injection cavity, restricts the molten plastic. After the plastic is formed, the ejector ring, under the action of the pusher, connecting plate, and support rod, ejects the PVC pipe formed in the injection cavity, which can facilitate the unloading of the formed PVC pipe.

[0011] Furthermore, it also includes a support ring, with the connecting plate slidably connected along the surface of the support ring, and the output end of the pusher passing through the support ring and connected to one of the connecting plates. Magnets capable of magnetic attraction are provided inside the connecting plate and the support ring. This allows the magnets to pull the connecting plate and the ejector ring back to their initial positions when the pusher disengages from pushing the connecting plate, preventing positional deviations in the ejector ring that could affect the quality of the formed PVC pipe.

[0012] Furthermore, it also includes a reversing valve connected to the water guide pipe, which controls the forward or reverse flow of the medium in the water guide pipe. Although the heat dissipation water channels in each lower mold are connected in parallel, the heat dissipation water channels between the cores and cavities inside a single lower mold are connected in series due to the influence of the spatial structure. By controlling the alternating forward and reverse flow of the medium in the water guide pipe, the high-temperature area that was originally at the end of the series water channel and had poor cooling effect can be periodically transformed into the beginning and obtain the strongest cooling effect. This smooths out the temperature difference of the entire mold over time, and further avoids the formation of extreme low thermal conductivity and high thermal conductivity areas within the mold.

[0013] Furthermore, it also includes an injection molding barrel located above the upper mold and a lifting mechanism that drives the injection molding barrel to rise and fall. The injection molding barrel is equipped with a screw for extruding molten plastic, and the outside of the injection molding barrel is equipped with a power mechanism that drives the screw to rotate. When the injection molding machine barrel is raised or lowered or the screw is rotated, the reversing valve intermittently and alternately controls the forward and reverse flow of the medium in the water guide pipe.

[0014] By controlling the operation of the reversing valve through the movement of the injection molding machine barrel, the flow of the medium in the water guide pipe can be controlled in a convenient and precise manner, increasing the overall stability of the injection molding process.

[0015] Furthermore, the reversing valve includes a first valve body and a second valve body connected in series. Both the first valve body and the second valve body are provided with valve cores. The valve cores are provided with a first flow channel and a second flow channel that allow the liquid to flow in the forward or reverse direction. The power mechanism is connected to a conversion shaft, the conversion shaft is splined to a first adjusting gear, the first adjusting gear is connected to a first cam, and the valve core of the first valve body is provided with a second push rod that abuts against the first cam. The conversion shaft is also provided with several toothed rings with equal tooth pitches. The toothed rings mesh with a second adjusting gear. The second adjusting gear is connected to a second cam. The valve core of the second valve body is provided with a second push rod that abuts against the second cam. The first cam and the second cam have a first wheel diameter and a second wheel diameter, so as to push the first push rod and the second push rod to the first position or the second position, so that the first flow channel or the second flow channel of the valve core is connected to the water guide pipe.

[0016] The lifting and lowering of the injection molding machine barrel and the rotation of the screw are intertwined. When the injection molding machine barrel lifts and lowers, it drives the gear ring to lift and lower, causing the second adjusting gear and the second cam to drive the second push rod to move, thereby changing and adjusting the flow direction of the medium in the second valve body. When the screw in the injection molding machine rotates, it drives the first adjusting gear to rotate, causing the second cam to drive the first push rod to move, thereby changing and adjusting the flow direction of the medium in the first valve body, thus maintaining the overall adjustment action of the medium flow direction in the water guide pipe.

[0017] Furthermore, it also includes a water pump that drives the flow of the medium within the water guide pipe and a triggering mechanism that activates the water pump. This mechanism includes a moving contact connected to the injection molding barrel and a stationary contact that can electrically contact the moving contact. When the injection molding barrel moves to the closed state of the upper and lower molds, the moving contact and the stationary contact become electrically connected, causing the water pump to start. In this way, the flow of the medium within the water guide pipe can be triggered only after the injection molding barrel reaches a set position, preventing premature flow of the medium within the water guide pipe from causing the core and cavity temperatures to drop too low, thus affecting the molding quality of the PVC pipe.

[0018] Based on the same inventive concept, the present invention provides an injection molding method for impact-resistant PVC pipes, comprising using the above-mentioned injection molding apparatus to injection mold PVC pipes.

[0019] Furthermore, the injection molding process for PVC pipes is as follows: Step S1: The upper mold and lower mold are closed, and molten plastic is injected into the injection gap; Step S2: The turntable rotates, causing the lower mold to rotate to the next position for idle cooling. The next lower mold rotates to the position below the upper mold for molten plastic injection. Step S3: The turntable rotates to unload the cooled, molded PVC pipe. During steps S1-S3, the water guide plate supplies cooling medium to the heat dissipation water channels of each lower mold in parallel.

[0020] Compared with existing technologies, this method utilizes the water guide plate to ensure that the heat dissipation water channels in each lower mold can maintain a parallel connection in a compact environment, and can maintain a stable and sealed connection during the rotation of the lower mold. This avoids excessive temperature rise in a single heat dissipation water channel, thereby preventing the formation of extreme low and high thermal conductivity areas within the mold. Consequently, it improves the impact resistance of PVC pipes molded in the same batch, enhances the overall product quality consistency, and reduces the scrap rate. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This paper shows a side view of an impact-resistant PVC pipe injection molding apparatus according to an embodiment of this application; Figure 2 This shows a schematic diagram of another side of an impact-resistant PVC pipe injection molding apparatus according to an embodiment of this application; Figure 3 This paper shows a schematic diagram of the water guide plate connection structure in an impact-resistant PVC pipe injection molding device according to an embodiment of this application; Figure 4 This paper shows a schematic diagram of the internal structure of the water guide plate in an impact-resistant PVC pipe injection molding device according to an embodiment of this application; Figure 5 It shows Figure 4 Enlarged view of section A in the middle; Figure 6 This paper shows a schematic diagram of the core and cavity connection in an impact-resistant PVC pipe injection molding device according to an embodiment of this application; Figure 7 This paper shows a schematic diagram of the conversion shaft connection in an impact-resistant PVC pipe injection molding device according to an embodiment of this application; Figure 8 This paper shows a schematic diagram of the reversing valve adjustment in an impact-resistant PVC pipe injection molding device according to an embodiment of this application; Figure 9 The diagram shows the water pump start-up principle in an impact-resistant PVC pipe injection molding device according to an embodiment of this application. Detailed Implementation

[0023] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0024] The reference numerals in the accompanying drawings include: 1. Frame; 2. Turntable; 3. Lower mold; 3. Cavity; 301. Core; 302. Connecting column; 303. Cover plate; 4. Lifting cylinder; 5. Injection barrel; 6. Heater; 7. Guide column; 8. Inner nest; 9. Screw motor; 10. Reduction gear pair; 11. Conversion shaft; 12. Support rod; 13. Connecting plate; 14. Ejection cylinder; 15. Support ring; 16. First disc; 17. Second disc; 18. Main shaft; 19. First water pipe; 20. Second water pipe; 21. First water guide branch pipe; 2 2. Second water guide branch pipe 23, sealing ring 24, sealing block 25, ejector ring 26, sleeve 27, first adjusting gear 28, driven gear 29, first cam 30, first valve body 31, first push rod 32, first return spring 33, gear ring 34, second adjusting gear 35, second cam 36, second valve body 37, second push rod 38, second return spring 39, first flow channel 40, second flow channel 41, triggering mechanism 42, coil 43, normally open contact 44, normally closed switch 45.

[0025] An impact-resistant PVC pipe injection molding apparatus, for example... Figure 1 and Figure 2 As shown: It includes a frame 1, a turntable 2 mounted on the frame 1, and a support frame located above the turntable 2.

[0026] The turntable 2 is rotatably connected to the frame 1 via a main shaft 19. A stepper motor is installed inside the frame 1 to drive the main shaft 19 to rotate 90° each time. Four lower molds 3 are installed on the turntable 2, located on the front, back, left, and right sides respectively. The lower mold 3 on the front is at the material feeding station, the lower mold 3 on the right is at the negative pressure dust removal station, the lower mold 3 on the rear is at the melt injection station, and the lower mold 3 on the left is at the melt cooling station. Symmetrically arranged on the frame 1 are cover plates 4 on the left and right sides of the upper surface of the turntable 2. The left cover plate 4 is fitted to the end face of the lower mold 3, and the right cover plate 4 is connected to a negative pressure pipe and a negative pressure fan. The negative pressure pipe is connected to the top of the lower mold 3 via a negative pressure suction cup.

[0027] Each lower mold 3 is equipped with multiple cores 302 and cavities 301. The cores 302 and cavities 301 form an injection gap that is compatible with the PVC pipe, so that multiple PVC pipes can be injection molded simultaneously in one injection process.

[0028] The support frame is equipped with a hopper, an injection molding barrel 6 connected to the hopper, and a lifting mechanism that drives the hopper and the injection molding barrel 6 to move up and down. The hopper is used to hold plastic granules. A heater 7 is installed on the side wall of the injection molding barrel 6 to heat the plastic granules to form molten plastic. A screw is installed inside the plastic barrel to drive the plastic granules and molten plastic to move. A screw motor 10 is installed at the top of the plastic barrel to drive the screw to rotate. The screw is vertically downward and a nozzle and an upper mold plate are installed at the bottom end of the plastic barrel. The upper mold plate and the lower mold plate are closed to inject molten plastic into the injection gap. The lifting mechanism is a lifting cylinder 5. The output end of the lifting cylinder 5 is connected to the frame that fixes the injection molding barrel 6.

[0029] like Figure 3 and Figure 6 As shown, an ejection mechanism is provided within the frame 1. The ejection mechanism includes a pusher located below the lower mold 3 at the front, connecting plates 14 respectively located below each lower mold 3 and pushed by the pusher, support rods 13 mounted on the connecting plates 14 and extending into each injection cavity, and ejection rings 26 located within each injection cavity. The pusher is an ejection cylinder 15. The core 302 and cavity 301 are connected by a connecting post 303, and a cooling water channel passes through the cavity 301, connecting post 303, and core 302. The connecting post 303 and support rod 13 are perpendicular to each other; that is, the connecting post 303 is located on the left and right sides of the injection cavity, while the support rod 13 is located on the front and rear sides of the injection cavity.

[0030] During the injection molding process, the ejector ring 26, as the bottom end of the injection gap, restricts the molten plastic. After the plastic is formed, the ejector ring 26, under the action of the ejector cylinder 15, the connecting plate 14, and the support rod 13, ejects the PVC pipe formed in the injection gap, which can facilitate the unloading of the formed PVC pipe.

[0031] A support ring 16 is also provided inside the frame 1. The connecting plate 14 is slidably connected along the surface of the support ring 16, and the output end of the pusher passes through the support ring 16 and is connected to the connecting plate 14 located on the front side. The interior of the connecting plate 14 and the interior of the support ring 16 are provided with magnets that can magnetically attract each other. When the pusher is disengaged from pushing the connecting plate 14, the connecting plate 14 and the ejector ring 26 are reset under the action of gravity. The attraction of the magnets can drive the connecting plate 14 and the ejector ring 26 to the initial position, preventing the position of the ejector ring 26 from deviating and affecting the quality of the formed PVC pipe.

[0032] like Figure 3 and Figure 4As shown, a water guide plate coaxial with the main shaft 19 is fixedly installed in the frame 1 by a mounting bracket. The water guide plate includes a first plate body 17 and a second plate body 18 arranged vertically. The first plate body 17 and the second plate body 18 are separated from each other. The inner walls of the first plate body 17 and the second plate body 18 are respectively connected to the first water guide branch pipe 22 and the second water guide branch pipe 23. The outer walls of the first plate body 17 and the second plate body 18 are rotatably sealed with sealing rings 24. Four water guide cavities are provided through both sides of the sealing rings 24. The water guide cavities of the upper and lower sealing rings 24 are respectively connected to the first water pipe 20 and the second water pipe 21. The first water pipe 20 and the second water pipe 21 at the same position are connected to the same lower mold 3.

[0033] like Figure 5 As shown, sealing blocks 25 are provided on the inner walls of the first disc 17 and the second disc 18 near the right side. When the sealing ring 24 rotates to the position near the right side, the sealing block 25 blocks the water channel, and the corresponding heat dissipation water channel in the lower mold 3 stops flowing, preventing the heat dissipation medium from reducing the temperature of the core 302 and the cavity 301 too much and affecting the subsequent PVC pipe molding quality.

[0034] Each of the first water guide branch pipes 22 and the second water guide branch pipes 23 is connected to the first water guide pipe and the second water guide pipe, respectively. The flow direction of the medium in the first water guide pipe and the second water guide pipe is controlled by a reversing valve, such as... Figure 7 and Figure 8 As shown, the reversing valve includes a first valve body 31 and a second valve body 37 connected in series. The first valve body 31 contains a first valve core, which has a first flow channel 40 for forward flow of liquid within the first valve body 31 and a second flow channel 41 for reverse flow of liquid within the first valve body 31. Specifically, the first valve body 31 has four ports on each side: an inlet port and an outlet port on the left, and a first inlet and a second inlet port on the right. The first flow channel 40 consists of two parallel water channels connecting the inlet port to the first inlet port and the outlet port to the second inlet port. The second flow channel 41 consists of two inclined water channels connecting the inlet port to the second inlet port and the outlet port to the first inlet port. Similarly, the second valve core has a first flow channel 40 for forward flow of liquid within the second valve body 37 and a second flow channel 41 for reverse flow of liquid within the second valve body 37.

[0035] The first water inlet and the second water inlet of the first valve body 31 are connected to the inlet and outlet of the second valve body 37, respectively, while the first water inlet and the second water inlet of the second valve body 37 are connected to the first water guide pipe and the second water guide pipe, respectively.

[0036] like Figure 7As shown, a conversion shaft 12 is connected to the output end of the screw motor 10 via a reduction gear pair 11. A sleeve 27 is rotatably connected inside the frame 1. The inner wall of the sleeve 27 is splinedly connected to the outer wall of the conversion shaft 12. A first adjusting gear 28 is installed on the outer wall of the sleeve 27. The first adjusting gear 28 meshes with a driven gear 29. The driven gear 29 is coaxially connected to a first cam 30. A first valve core is connected to a first push rod 32. The end of the first push rod 32 extends out of the first valve body 31 and is provided with a ball that abuts against the side wall of the first cam 30. A limiting ring is provided at the end of the first push rod 32. A first return spring 33 is provided between the limiting ring and the first valve body 31.

[0037] At the bottom of the conversion shaft 12, there are also several toothed rings 34 with equal tooth pitch. A second adjusting gear 35 that meshes with the toothed rings 34 is rotatably connected inside the frame 1. A second cam 36 is coaxially connected to the second adjusting gear 35. A second push rod 38 is connected to the second valve core. The end of the second push rod 38 extends out of the second valve body 37 and is provided with a ball that abuts against the side wall of the second cam 36. A limiting ring is also provided at the end of the second push rod 38. A second return spring 39 is provided between the limiting ring and the second valve body 37.

[0038] The first cam 30 and the second cam 36 have a first wheel diameter and a second wheel diameter, so as to push the first push rod 32 and the second push rod 38 to the first position or the second position, so that the first flow channel 40 or the second flow channel 41 of the first valve core and the second valve core are in the connected position.

[0039] During the process of changing the direction of medium flow, the medium flow rate during a single change is greater than the total liquid flow rate between the inlet and outlet ports of the first valve body 31. To prevent the medium from continuously flowing back and forth in the pipeline, a high-pressure water pump that can keep the coolant in a turbulent state should be used.

[0040] The cooling medium is supplied by a water pump, such as Figure 1 and Figure 9 As shown, a triggering mechanism 42 is provided between the bottom of the heater 7 on the outer wall of the injection molding machine barrel 6 and the support frame to start the water pump. Specifically, a guide post 8 is provided at the bottom of the heater 7 on the outer wall of the injection molding machine barrel 6, and an inner nest 9 is provided on the support frame. A moving contact is provided at the bottom of the guide post 8, and a stationary contact is provided at the bottom of the inner nest 9. When the injection molding machine barrel 6 moves to the closed state of the upper mold and the lower mold 3, the moving contact and the stationary contact are electrically connected, so that the power supply of the water pump is turned on. At the same time, the relay coil 43 in the circuit is energized. The normally open contact 44 of the relay is connected in parallel with the triggering mechanism 42 and closes after the coil 43 is energized. A normally closed switch 45 is also provided in the circuit to control the overall on / off state.

[0041] When the moving contact and the stationary contact are electrically connected, the water pump starts, and the relay keeps it continuously energized, continuously supplying the cooling medium. Once the injection molding is completed within the corresponding time period, the circuit is disconnected by the normally closed switch 45.

[0042] Based on the same inventive concept, another embodiment provides a method for injection molding impact-resistant PVC pipes, including injection molding the PVC pipes using the injection molding apparatus described above, with the following steps: In step S1, the stepper motor drives the main shaft 19 and the turntable 2 to rotate intermittently at a 90° angle, so that the lower mold 3 rotates to the rear side and is located below the upper mold. The lifting cylinder 5 drives the injection barrel 6 to rise and fall, and at the same time the screw drives the screw to rotate. The heater 7 heats the plastic particles. When the injection barrel 6 moves to the state where the upper mold and the lower mold 3 are closed, the moving contact and the stationary contact are electrically connected, so that the water pump starts to supply the cooling medium. At the same time, the nozzle opens to inject molten plastic into the injection gap. Step S2: After the lower mold 3 is injected, the screw motor 10 stops, the lifting cylinder 5 drives the injection molding machine barrel 6 to rise, the turntable 2 rotates, so that the lower mold 3 rotates to the left side for idle cooling, and the next lower mold 3 rotates to the bottom of the upper mold for injection of molten plastic. In step S3, the turntable 2 rotates, causing the lower mold 3 to rotate to the front for unloading. Under the action of the ejection cylinder 15, the connecting plate 14, and the support rod 13, the ejection ring 26 ejects the PVC pipe formed in the injection gap. Step S4: Turntable 2 rotates, causing the lower mold 3 to rotate to the right side for negative pressure dust removal; Step S5: Turntable 2 rotates, so that lower mold 3 is once again in the rear position for molten plastic injection molding; Repeat steps S2 to S5 to complete the injection molding of PVC pipes for the corresponding time or batch, and then disconnect the water pump through normally closed switch 45.

[0043] During steps S2 to S4, although the heat dissipation water channels in each lower mold 3 are connected in parallel, the heat dissipation water channels between each core 302 and cavity 301 inside a single lower mold 3 are connected in series due to the influence of the spatial structure. By controlling the alternating forward and reverse flow of the medium in the water guide pipe, the high-temperature area that was originally at the end of the series water channel and had poor cooling effect can be periodically transformed into the beginning and obtain the strongest cooling effect. This flattens out the temperature difference of the entire mold in the time dimension, and further avoids the formation of extreme low thermal conductivity areas and high thermal conductivity areas in the mold. Furthermore, during this process, the lifting and lowering of the injection molding machine barrel 6 and the rotation of the screw are interleaved. When the injection molding machine barrel 6 lifts and lowers, it drives the gear ring 34 to lift and lower, causing the second adjusting gear 35 and the second cam 36 to drive the second push rod 38 to move, thereby changing and adjusting the flow direction of the medium in the second valve body 37. When the screw in the injection molding machine rotates, it drives the first adjusting gear 28 to rotate, causing the second cam 36 to drive the first push rod 32 to move, thereby changing and adjusting the flow direction of the medium in the first valve body 31, thus maintaining the overall adjustment action of the medium flow direction in the water guide pipe.

[0044] In step S3, the sealing block 25 blocks the water channel, and the corresponding heat dissipation water channel in the lower mold 3 stops flowing, preventing the heat dissipation medium from reducing the temperature of the core 302 and cavity 301 too much and affecting the subsequent PVC pipe molding quality.

[0045] Compared with the prior art, the present invention utilizes the water guide plate to ensure that the heat dissipation water channels in each lower mold 3 can maintain a parallel connection in a compact environment, and can maintain a sealed and stable connection during the rotation of the lower mold 3. This avoids excessive temperature rise in a single heat dissipation water channel, thereby preventing the formation of extreme low thermal conductivity and high thermal conductivity areas in the mold. As a result, the impact resistance of PVC pipes molded in the same batch is improved, the overall product quality consistency is improved, and the scrap rate is reduced.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An injection molding device for impact-resistant PVC pipes, characterized in that, include: A turntable with several lower molds on it, one of which has an upper mold directly above it. The lower mold includes a core and a cavity, and an injection gap is formed between the core and the cavity. A water guide plate includes a plate body and a sealing ring that is rotatably sealed to the outer wall of the plate body. The plate body is connected to a water guide pipe, and the side wall of the sealing ring is provided with several water guide cavities that communicate with the interior of the plate body. The core and cavity are equipped with heat dissipation water channels, and water pipes are connected between the heat dissipation water channels and the water guiding cavity. There are two water guide plates, which are respectively connected to both ends of the heat dissipation water channel.

2. The impact-resistant PVC pipe injection molding device according to claim 1, characterized in that, The lower mold also includes connecting columns symmetrically arranged between the core and the cavity, and the heat dissipation water passage passes through the cavity, the connecting columns, and the core.

3. The impact-resistant PVC pipe injection molding device according to claim 1, characterized in that, It also includes the ejector mechanism, including: The ejector ring is adapted to the injection gap, and each ejector ring is symmetrically connected with a support rod, the bottom of which protrudes through the lower mold. The connecting plate connects to the ends of each support rod in the same lower mold. The pusher component pushes the connecting plate to move vertically.

4. The impact-resistant PVC pipe injection molding device according to claim 3, characterized in that, It also includes a support ring, the connecting plate is slidably connected along the surface of the support ring, and the output end of the pusher passes through the support ring and is connected to one of the connecting plates. The interior of the connecting plate and the interior of the support ring are provided with magnets that can magnetically attract each other.

5. The impact-resistant PVC pipe injection molding device according to claim 1, characterized in that, It also includes a reversing valve connected to the water guide pipe, which controls the forward or reverse flow of the medium in the water guide pipe.

6. The impact-resistant PVC pipe injection molding device according to claim 5, characterized in that, It also includes an injection molding barrel located above the upper mold and a lifting mechanism that drives the injection molding barrel to rise and fall. The injection molding barrel is equipped with a screw that extrudes molten plastic, and the outside of the injection molding barrel is equipped with a power mechanism that drives the screw to rotate. When the injection molding machine barrel is raised or lowered or the screw is rotated, the reversing valve intermittently and alternately controls the forward and reverse flow of the medium in the water guide pipe.

7. The impact-resistant PVC pipe injection molding device according to claim 6, characterized in that, The reversing valve includes a first valve body and a second valve body connected in series. Both the first valve body and the second valve body are provided with valve cores. The valve cores are provided with a first flow channel and a second flow channel that allow the liquid to flow in the forward or reverse direction. The power mechanism is connected to a conversion shaft, the conversion shaft is splined to a first adjusting gear, the first adjusting gear is connected to a first cam, and the valve core of the first valve body is provided with a second push rod that abuts against the first cam. The conversion shaft is also provided with several toothed rings with equal tooth pitches. The toothed rings mesh with a second adjusting gear. The second adjusting gear is connected to a second cam. The valve core of the second valve body is provided with a second push rod that abuts against the second cam. The first cam and the second cam have a first wheel diameter and a second wheel diameter, so as to push the first push rod and the second push rod to the first position or the second position, so that the first flow channel or the second flow channel of the valve core is connected to the water guide pipe.

8. The impact-resistant PVC pipe injection molding apparatus according to any one of claims 5-7, characterized in that, It also includes a water pump that drives the flow of medium in the water guide pipe and a triggering mechanism that drives the water pump to start. The mechanism includes a moving contact connected to the injection molding barrel and a stationary contact that can make electrical contact with the moving contact. When the injection molding barrel moves to the state where the upper mold and the lower mold are closed, the moving contact and the stationary contact are electrically connected, and the water pump is started.

9. A method for injection molding impact-resistant PVC pipes, characterized in that, This includes using the injection molding apparatus according to any one of claims 1-8 to injection mold PVC pipes.

10. The method for injection molding impact-resistant PVC pipes according to claim 9, characterized in that, The steps for injection molding PVC pipes are as follows: Step S1: The upper mold and lower mold are closed, and molten plastic is injected into the injection gap; Step S2: The turntable rotates, causing the lower mold to rotate to the next position for idle cooling. The next lower mold rotates to the position below the upper mold for molten plastic injection. Step S3: The turntable rotates to unload the cooled, molded PVC pipe. During steps S1-S3, the water guide plate supplies cooling medium to the heat dissipation water channels of each lower mold in parallel.

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