Automobile water pipe cutting-free forming die device and use method

Abstract

The application relates to the technical field of mold forming, in particular to an automobile water pipe cutting-free forming mold device and a use method thereof, which comprises a lower mold, a lower mold core arranged on the lower mold, an upper mold capable of being opened and closed and arranged above the lower mold, an upper mold core arranged below the upper mold, an injection channel communicated with the upper mold core and arranged on the upper mold, a cooling injection groove arranged at the bottom end of the lower mold core, a small-diameter point gate arranged at the joint of the injection channel and a forming cavity, the point gate can be automatically pulled off during mold opening, a core rod assembly arranged between the lower mold core and the upper mold core, a positioning assembly arranged on the lower mold and used for limiting and positioning the installation of the core rod assembly and also used for sealing the forming cavity between the lower mold core and the upper mold core, the core rod assembly being arranged in the forming cavity and surrounding the positioning assembly and the forming cavity to form a forming space of the automobile water pipe, and a pressure relief structure communicated with the forming cavity and capable of being operated to release pressure being arranged in the lower mold core.

Description

Technical Field

[0001] This invention relates to the field of mold forming technology, specifically to a cutting-free mold device for automotive water pipes and its usage method. Background Technology

[0002] Water pipes in automotive cooling and heating systems are mostly made of rubber or thermoplastic elastomers, and their shape is often U-shaped or has a bend to accommodate the space arrangement in the engine compartment. Current technology presents the following problems in the molding of these bent water pipes: 1. Difficult post-gating treatment: Traditional molds use side gates or large gates for injection, leaving residual material on the molded product, requiring manual or mechanical cutting. This involves multiple steps, low efficiency, and the cut surface is prone to burrs or defects. 2. Difficulty in core extraction from the U-shaped bend: The inner cavity of the U-shaped water pipe is curved, making it impossible to pull out the rigid integral core rod axially. Existing solutions include: ① Half-mold structure, which divides the cavity into two halves, removes the product with the mandrel after mold opening, and then pulls the core. However, the half-mold structure is complex, and the parting line affects the product's appearance and sealing performance; ② Flexible mandrel (such as spring mandrel, rubber mandrel), which is pulled out by the deformation of the mandrel itself. However, flexible mandrels have poor molding accuracy, short lifespan, and unstable internal surface quality of the product; ③ Hydraulic cylinder-driven rotary core pulling or segmented slider core pulling, which has a complex structure, high cost, and difficult maintenance. 3. Uncontrollable venting and pressure relief: Rubber / elastomer materials have poor fluidity during injection, and air in the cavity is not easily expelled, easily causing defects such as bubbles, material shortage, and scorching. Existing molds mostly use fixed venting grooves, and the venting volume is not adjustable, which cannot adapt to different materials and process parameters. 4. Uneven product elasticity: Uneven cooling or holding pressure leads to inconsistent elasticity in different parts of the product, making it easy to tear or deform during core pulling. Therefore, there is an urgent need for an automotive water pipe molding mold with a simple structure, high molding accuracy, no need for post-cutting, convenient core pulling, and controllable venting. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a cutting-free molding device and method for forming automotive water pipes. By combining automatic breakage at the injection gate, segmented core pulling with a rigid U-shaped mandrel, and dynamic pressure relief and holding, cutting-free, high-precision, and high-efficiency bending water pipe forming is achieved.

[0004] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a cutting-free molding device for automotive water pipes, comprising a lower mold, a lower core on the lower mold, an upper mold above the lower mold capable of opening and closing, an upper core below the upper mold, an injection channel on the upper mold communicating with the upper core, a cooling injection groove at the bottom of the lower core, a small-diameter point gate at the connection between the injection channel and the molding cavity, the point gate automatically breaking off when the mold is opened; a mandrel assembly between the lower core and the upper core, a positioning component on the lower mold for limiting and positioning the installation of the mandrel assembly, and the positioning component also for sealing the molding cavity between the lower core and the upper core, the mandrel assembly being placed in the molding cavity and enclosing the positioning component and the molding cavity to form the molding space of the automotive water pipe, and a pressure relief structure communicating with the molding cavity and capable of pressure relief in the lower core. This mold device achieves cutting-free molding through point gates, high-precision molding of curved water pipes through the cooperation of mandrel and positioning components, and automatic pressure stabilization and venting during the injection process through a pressure relief structure. The three work together to ensure product quality and simplify subsequent processes.

[0005] Optionally, the mandrel assembly includes a U-shaped tube segment and two straight tube segments, which are detachably connected to the U-shaped tube segment. The U-shaped tube segment is a rigid tube. The U-shaped tube segment is made of stainless steel or aluminum alloy, possessing high rigidity and surface finish to ensure the dimensional accuracy and surface quality of the water pipe's inner cavity after molding. The two straight tube segments are respectively connected to both ends of the U-shaped tube segment, making the mandrel assembly U-shaped to fit the inner cavity shape of curved water pipes. The detachable connection facilitates segmented removal during mandrel extraction.

[0006] Optionally, a sealing ring is provided between the straight pipe section and the U-shaped pipe section. The sealing ring is made of heat- and oil-resistant rubber and is fitted onto the threaded connection between the straight pipe section and the U-shaped pipe section to prevent molten material from seeping into the mandrel through the thread gap during injection, ensuring that the inner wall of the product is free of flash.

[0007] Optionally, the positioning assembly includes a positioning plate, which is mounted on the lower mold and abuts against the side wall of the lower core, and is used to seal the end of the molding cavity. The positioning plate contains hollow sleeves that are detachably connected to the two ends of the U-shaped tube segment. Each of the two hollow sleeves has a fixing plate connected to the positioning plate. Each hollow sleeve has a lateral locking pin that contacts the fixing plate and locks the hollow sleeve. The positioning plate is fixed to the lower mold, with one side tightly fitted against the side wall of the lower core to block communication between the end of the molding cavity and the outside. The hollow sleeve passes through the through hole in the positioning plate and screws onto the end of the U-shaped tube segment, achieving axial positioning of the mandrel assembly. The fixing plate presses against the flange end face of the hollow sleeve, and the lateral locking pin passes through the positioning hole on the fixing plate and inserts into the locking hole of the hollow sleeve to prevent the hollow sleeve from loosening under injection pressure.

[0008] Optionally, each end of the U-shaped tube segment is connected to a pull rope. The pull rope is arranged inside the hollow sleeve and leads out through the lateral locking pin to form a core-pulling operation end. When pulling the core, the operation end is pulled to remove the U-shaped tube segment. The positioning plate is provided with a collar that is loosely fitted with the two straight tube segments and seals the forming cavity. The pull rope is made of high-strength nylon or steel wire. One end is tied or riveted to the hanging hole at the end of the U-shaped tube segment, and the other end passes through the inner cavity of the hollow sleeve and leads out through the through hole in the middle of the lateral locking pin to form a core-pulling operation end that can be held by the operator. The collar is made of elastic wear-resistant material. Its inner hole is clearance-fitted with the outer wall of the straight tube segment. When the material is injected, the pressure in the forming cavity acts on the end face of the collar, causing it to expand radially slightly, thereby filling the gap between the collar and the straight tube segment and realizing dynamic sealing of the end of the forming cavity.

[0009] Optionally, two straight pipe sections are threaded onto the two ends of a U-shaped pipe section, and two hollow sleeves are threaded onto the two ends of a U-shaped pipe section. Two fixing plates are bolted to a positioning plate, and two collars on the positioning plate are inserted into the forming cavity between the lower and upper cores. The straight pipe sections and the U-shaped pipe section have external thread engagement, and the hollow sleeves and the U-shaped pipe section have internal thread engagement. They are coaxially arranged and separated by the wall of the U-shaped pipe section, so they do not interfere with each other. The fixing plate is bolted to the outer end face of the positioning plate, pressing the flange of the hollow sleeve between the positioning plate and the fixing plate. One end of the collar is embedded in the mounting hole of the positioning plate, and the other end extends into the end of the forming cavity by about 3 to 5 mm, which serves a sealing function without affecting the shape of the product end face.

[0010] Optionally, the pressure relief structure includes a pressure relief channel disposed in the lower core and connected to the molding cavity. A secondary pressure relief channel is disposed on the side wall of the pressure relief channel and connected thereto. A conformal sealing block is disposed in the pressure relief channel and can reciprocate and reset along the axial direction of the pressure relief channel. The conformal sealing block is used to seal the air inlet end of the secondary pressure relief channel. A push rod connected to the conformal sealing block is disposed in the pressure relief channel. A sleeve is disposed outside the lower core. An adjusting screw is disposed in the sleeve. A T-shaped positioning block connected to the adjusting screw is disposed at the inner end of the adjusting screw. A compression spring connected to the push rod is disposed on the T-shaped positioning block. The pressure relief channel is horizontally located inside the lower core, with one end connected to the molding cavity and the other end extending to the outside of the lower core and sealed by a sealing plate. The secondary pressure relief channel is located within the pressure relief channel, serving as an outlet for exhaust overflow. The head contour of the contoured sealing block is adapted to the cross-section of the pressure relief channel, and under the preload of the compression spring, it fits against the port of the air inlet of the secondary pressure relief channel to achieve a seal. The push rod transmits the medium pressure received by the contoured sealing block to the compression spring. The adjusting screw changes the axial position of the T-shaped positioning block by rotation, thereby adjusting the compression and preload of the compression spring, achieving stepless adjustment of the pressure relief opening pressure.

[0011] Optionally, the pressure relief channel is provided with a sealing plate for sealing the pressure relief channel, the push rod passes through the sealing plate and extends into the sleeve, a return spring that elastically returns to its original position is sleeved on the push rod between the sealing plate and the conformal sealing block, and a locking pin that can assist in limiting and locking the push rod is provided on the sleeve.

[0012] Optionally, the lower core is further provided with a limiting ring to limit the movement of the outer end of the push rod; the sealing plate is located on the side of the air inlet end of the secondary pressure relief channel and does not block the air outlet end of the secondary pressure relief channel. The sealing plate is set inside the pressure relief channel, sealing the main passage of the pressure relief channel, forcing the gas in the cavity to be discharged only through the secondary pressure relief channel; a guide sleeve or sealing packing is provided between the push rod and the sealing plate to ensure the sealing performance when the push rod moves back and forth; the return spring is sleeved on the push rod and is in a pre-compressed state, with one end abutting the sealing plate and the other end abutting the conformal sealing block, and together with the compression spring, it provides the reset force; the locking pin is radially screwed into the side wall of the sleeve and abuts the outer wall of the push rod, locking the initial position of the push rod after the pressure adjustment is completed, preventing changes in the preload due to transportation or vibration.

[0013] This invention also provides a method for using a cutting-free automotive water pipe forming mold device, characterized by comprising the following steps: Step 1: Assemble the mandrel: Place the sealing ring at the connection between the straight pipe section and the U-shaped pipe section, and screw the two straight pipe sections to the two ends of the U-shaped pipe section respectively to form the mandrel assembly; Step 2: Positioning and Installation: Place the mandrel assembly into the molding cavity of the lower core, install the positioning plate and abut it against the side wall of the lower core, screw the hollow sleeve into the end of the U-shaped tube section, insert the collar along with the positioning plate into the end of the molding cavity, fix the fixing plate to the positioning plate with bolts, insert the lateral locking pin to lock the hollow sleeve, and lead the pull rope out through the lateral locking pin along the inside of the hollow sleeve to form the core pulling operation end.

[0014] Step 3: Pressure Preset: Rotate the adjusting screw to compress the pressure spring through the T-shaped positioning block to preset the pressure relief opening pressure, and tighten the locking pin to fix the push rod. Step 4: Mold closing and material injection: Close the upper mold, and inject the molten material into the molding cavity through the small-diameter point gate at the end of the injection channel; Step 5: Pressure relief and pressure holding: During the injection and pressure holding process, the pressure in the molding cavity increases, pushing the contour sealing block to compress the clamping spring and return spring to move backward, so that the secondary pressure relief channel is opened to exhaust and overflow. After the pressure in the cavity decreases, the contour sealing block resets and closes the secondary pressure relief channel under the action of the double spring. This automatic cycle maintains the stability of the molding cavity pressure. The outer end of the push rod is limited by the limit ring to prevent excessive backward movement. Step Six: Cooling and Shaping: Cooling medium is introduced into the cooling injection groove at the bottom of the mold core to cool and shape the product in the molding cavity; Step 7: Mold opening and sprue breaking: After cooling and solidification, the mold is opened and the upper mold rises. Due to the small cross-sectional area and stress concentration at the sprue, the material is automatically pulled off and the material detaches from the upper mold. Step 8: Segmented Core Removal: First, pull out the side locking pin and disconnect the connection between the fixing plate and the positioning plate. Unscrew the hollow sleeve from the end of the U-shaped pipe segment. Then, unscrew the two straight pipe segments from the end of the U-shaped pipe segment. Finally, pull the operating end of the pull rope and use the elastic deformation of the formed water pipe itself to pull the U-shaped pipe segment out of the water pipe. Step 9: Remove the finished product: Remove the molded car water pipe from the lower core. The conformal sealing block is reset under the action of the compression spring and the return spring, ready for the next molding cycle.

[0015] The further aspect of this solution is that a sealing ring is provided between the lower core and the upper core to seal the inner and outer sides of the molding cavity.

[0016] (III) Beneficial Effects This invention provides a cutting-free molding device and method for forming automotive water pipes, which has the following beneficial effects: Compared with existing technologies, this invention relates to a cutting-free molding device and method for automotive water pipes. The injection channel ends with a small-diameter point gate. When the mold is opened, the gate automatically breaks due to the small cross-sectional area and stress concentration. The product end face is flush, eliminating the need for subsequent cutting processes, thus improving production efficiency and avoiding cutting defects.

[0017] Compared with existing technologies, this invention relates to a cutting-free molding die device and its usage method for automotive water pipes. The U-shaped pipe section is a rigid pipe, ensuring the precision of the molding cavity and the surface quality. The straight pipe section and the U-shaped pipe section are detachably connected. When pulling the core, the straight pipe section is removed first, and then the rigid U-shaped pipe section is pulled out by the elastic deformation of the molding water pipe itself through the pull rope. It eliminates the need for a split mold, hydraulic cylinder, or flexible mandrel, resulting in a simple structure, low cost, and stable product quality.

[0018] Compared with existing technologies, this new automotive water pipe cutting-free molding die device and its usage method set the pressure relief opening pressure by adjusting the screw to preset the clamping spring preload; during the injection process, the conformal sealing block automatically opens and closes, and the secondary pressure relief channel exhausts air from the side wall without the sealing plate blocking the air outlet, thus achieving automatic pressure stabilization and exhaust, ensuring that the product is dense, bubble-free, and has uniform elasticity, providing a quality foundation for subsequent core pulling.

[0019] Compared with existing technologies, this new automotive water pipe cutting-free molding die device and its usage method, with the positioning plate limiting and positioning the mandrel assembly and sealing the end of the molding cavity through the collar, and the injection pressure causing the collar to expand radially to achieve dynamic sealing, has a high degree of structural integration.

[0020] Compared with existing technologies, this new automotive water pipe cutting-free molding device and its usage method have three technical features that work together to produce an overall technical effect that cannot be achieved by any one of them: self-breaking of the point gate without cutting, dynamic pressure relief to ensure uniform product elasticity so that core pulling does not tear, and segmented core pulling so that the small diameter end can simultaneously accommodate the point gate and the sealing structure. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the upper core of the present invention; Figure 3 This is a schematic diagram of the internal structure of the core of the present invention; Figure 4 This is a cross-sectional structural schematic diagram of the injection channel of the present invention; Figure 5 This is a schematic diagram of the cross-sectional view of the core of the present invention; Figure 6 This is a schematic diagram of the pressure relief structure and pressure relief channel of the present invention; Figure 7 This is a schematic diagram of the pressure relief structure outside the core of the present invention; Figure 8 For the present invention Figure 6 A schematic diagram of the structure after mid-section view.

[0022] In the diagram: 1. Lower mold; 2. Lower core; 3. Upper mold; 4. Upper core; 5. Mandrel assembly; 6. Positioning assembly; 7. Pressure relief structure; 8. U-shaped pipe section; 9. Straight pipe section; 10. Sealing ring; 11. Positioning plate; 12. Hollow sleeve; 13. Fixing plate; 14. Lateral locking pin; 15. Pull rope; 16. Ring; 17. Pressure relief channel; 18. Secondary pressure relief channel; 19. Contouring sealing block; 20. Push rod; 21. Sleeve; 22. Adjusting screw; 23. T-shaped positioning block; 24. Compression spring; 25. Sealing plate; 26. Return spring; 27. Locking pin; 28. Limiting ring; 29. ​​Injection channel; 30. Cooling injection tank. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Please see Figures 1 to 8This invention provides a technical solution: a cutting-free molding device for automotive water pipes, comprising a lower mold 1, a lower core 2 on the lower mold 1, an upper mold 3 above the lower mold 1 capable of opening and closing, an upper core 4 below the upper mold 3, an injection channel 29 connected to the upper core 4 on the upper mold 3, a cooling injection groove 30 at the bottom end of the lower core 2, and a small-diameter point gate at the connection between the injection channel 29 and the molding cavity, which can be automatically broken off when the mold is opened; a mandrel assembly 5 is provided between the lower core 2 and the upper core 4, the mandrel assembly 5 comprising a U-shaped tube segment 8 and two straight tube segments 9, the two straight tube segments 9 being detachably connected to the U-shaped tube segment 8; the U-shaped tube segment 8 is a rigid tube, a sealing ring 10 is provided between the straight tube segments 9 and the U-shaped tube segment 8, and the lower mold 1 is provided with a limiting and positioning device for the installation of the mandrel assembly 5. The positioning component 6 is also used to seal the molding cavity between the lower core 2 and the upper core 4. The positioning component 6 includes a positioning plate 11, which is installed on the lower mold 1 and abuts against the side wall of the lower core 2 and is used to seal the end of the molding cavity. The positioning plate 11 is provided with hollow sleeves 12 that are detachably connected to the two ends of the U-shaped tube section 8. The two hollow sleeves 12 are respectively provided with fixing plates 13 connected to the positioning plate 11. The hollow sleeves 12 are provided with lateral locking pins 14 that can contact the fixing plates 13 and lock the hollow sleeves 12. The two ends of the U-shaped tube section 8 are respectively connected with pull ropes 15. The pull ropes 15 are arranged inside the hollow sleeves 12 and led out through the lateral locking pins 14 to form a core-pulling operation end. When pulling the core, the operation end is pulled to remove the U-shaped tube section 8.The positioning plate 11 is provided with two sleeves 16 that are loosely fitted to the two straight pipe sections 9 and seal the forming cavity. The two straight pipe sections 9 are screwed onto the two ends of the U-shaped pipe section 8. The two hollow sleeves 12 are screwed onto the two ends of the U-shaped pipe section 8. The two fixing plates 13 are fixedly installed on the positioning plate 11 with bolts. The two sleeves 16 on the positioning plate 11 are inserted into the forming cavity between the lower core 2 and the upper core 4. The mandrel assembly 5 is placed in the forming cavity and surrounds the positioning assembly 6 and the forming cavity to form the forming space of the automotive water pipe. The lower core 2 is provided with a pressure relief structure 7 that is connected to the forming cavity and can be pressure-relieved. The pressure relief structure 7 includes a pressure relief channel 17 that is provided in the lower core 2 and connected to the forming cavity. The side wall of the pressure relief channel 17 is provided with a secondary pressure relief channel 18 that is connected to it. The pressure relief channel 17 is provided with a contoured part that can move back and forth along the axial direction of the pressure relief channel 17 and reset. The sealing block 19, a contoured sealing block 19, is used to seal the air inlet end of the secondary pressure relief channel 18. A push rod 20 connected to the contoured sealing block 19 is provided inside the pressure relief channel 17. A sleeve 21 is provided outside the lower core 2, and an adjusting screw 22 is provided inside the sleeve 21. A T-shaped positioning block 23 connected to the adjusting screw 22 is provided at the inner end of the adjusting screw 22. A sealing plate 25 for sealing the pressure relief channel 17 is provided inside the pressure relief channel 17, and the push rod 20 passes through it. A return spring 26, which elastically returns to its original position, is fitted on the push rod 20 between the sealing plate 25 and the conformal sealing block 19. A locking pin 27, which can auxiliaryly limit and lock the push rod 20, is provided on the sleeve 21. A limiting ring 28, which limits the movement of the outer end of the push rod 20, is also provided on the outside of the lower core 2. The sealing plate 25 is located on the air inlet side of the secondary pressure relief channel 18 and does not obstruct the air outlet end of the secondary pressure relief channel 18.

[0025] Please see Figures 1 to 8 A method for using a cutting-free molding device for automotive water pipes, characterized by comprising the following steps: Step 1: Assemble the mandrel: Place the sealing ring 10 at the connection between the straight pipe section 9 and the U-shaped pipe section 8, and screw the two straight pipe sections 9 to the two ends of the U-shaped pipe section 8 respectively to form the mandrel assembly 5; Step 2: Positioning and Installation: Place the mandrel assembly 5 into the molding cavity of the lower core 2, install the positioning plate 11 and abut it against the side wall of the lower core 2, screw the hollow sleeve 12 into the end of the U-shaped tube section 8, insert the collar 16 into the end of the molding cavity along with the positioning plate 11, fix the fixing plate 13 to the positioning plate 11 with bolts, insert the lateral locking pin 14 to lock the hollow sleeve 12, and lead the pull rope 15 out through the lateral locking pin 14 along the inside of the hollow sleeve 12 to form the core pulling operation end.

[0026] Step 3: Pressure adjustment preset: Rotate the adjusting screw 22 to compress the clamping spring 24 through the T-shaped positioning block 23 to preset the pressure relief opening pressure, and tighten the locking pin 27 to help fix the push rod 20; Step 4: Mold closing and material injection: Close the upper mold 3, and inject the molten material into the molding cavity through the small-diameter point gate at the end of the injection channel 29; Step 5: Pressure relief and pressure holding: During the injection and pressure holding process, the pressure in the molding cavity increases, pushing the contour sealing block 19 to compress the clamping spring 24 and the return spring 26 to move backward, so that the secondary pressure relief channel 18 can be opened to release and overflow. After the pressure in the cavity decreases, the contour sealing block 19 resets and closes the secondary pressure relief channel 18 under the action of the double springs. This automatic cycle maintains the stability of the molding cavity pressure. The outer end of the push rod 20 is limited by the limit ring 28 to prevent excessive backward movement. Step 6: Cooling and Shaping: Cooling medium is introduced into the cooling injection groove 30 at the bottom of the downward core 2 to cool and shape the product in the molding cavity; Step 7: Mold opening and sprue breaking: After cooling and solidification, the mold is opened, the upper mold 3 rises, and the sprue is automatically pulled off due to the small cross-sectional area and stress concentration at the sprue point, and the material detaches with the upper mold 3. Step 8: Segmented core removal: First, pull out the side locking pin 14 and disconnect the connection between the fixing plate 13 and the positioning plate 11. Then, unscrew the hollow sleeve 12 from the end of the U-shaped pipe section 8. Next, unscrew the two straight pipe sections 9 from the end of the U-shaped pipe section 8. Then, pull the operating end of the pull rope 15 and use the elastic deformation of the formed water pipe itself to pull the U-shaped pipe section 8 out of the water pipe. Step 9: Remove the finished product: Remove the molded car water pipe from the lower core 2. The contour sealing block 19 is reset under the action of the compression spring 24 and the return spring 26, ready for the next molding cycle.

[0027] The electrical components mentioned in this article are all connected to an external main controller and 380V commercial power supply, and the main controller can be a conventional known device such as a computer that can control it.

[0028] In the description of this specification, the terms "connection", "installation", "fixing", "setting", etc. are interpreted broadly. For example, "connection" can be a fixed connection or an indirect connection through an intermediate component without affecting the relationship between components and the technical effect. It can also be an integral connection or a partial connection. In such cases, those skilled in the art can understand the specific meaning of the above terms in this invention or invention according to the specific circumstances.

[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A cutting-free molding device for automotive water pipes, comprising a lower mold (1), a lower core (2) on the lower mold (1), an upper mold (3) above the lower mold (1) capable of opening and closing, an upper core (4) below the upper mold (3), an injection channel (29) communicating with the upper core (4) on the upper mold (3), and a cooling injection groove (30) at the bottom end of the lower core (2), characterized in that: The connection between the injection channel (29) and the molding cavity is a small-diameter point gate, which can be automatically broken when the mold is opened; a mandrel assembly (5) is provided between the lower core (2) and the upper core (4), and a positioning component (6) is provided on the lower mold (1) for limiting and positioning the installation of the mandrel assembly (5), and the positioning component (6) is also used to seal the molding cavity between the lower core (2) and the upper core (4). The mandrel assembly (5) is placed in the molding cavity and surrounds the positioning component (6) and the molding cavity to form the molding space of the car water pipe. The lower core (2) is provided with a pressure relief structure (7) that is connected to the molding cavity and can perform pressure relief operation.

2. The automobile water pipe cutting-free forming mold device according to claim 1, characterized in that: The mandrel assembly (5) includes a U-shaped tube segment (8) and two straight tube segments (9), which are detachably connected to the U-shaped tube segment (8); the U-shaped tube segment (8) is a rigid tube.

3. The automotive water pipe cutting-free forming mold device according to claim 2, characterized in that: A sealing ring (10) is provided between the straight pipe section (9) and the U-shaped pipe section (8).

4. The automobile water pipe cutting-free forming mold device according to claim 1, characterized in that: The positioning component (6) includes a positioning plate (11), which is installed on the lower mold (1) and abuts against the side wall of the lower core (2) and is used to seal the end of the molding cavity. The positioning plate (11) is provided with hollow sleeves (12) that are detachably connected to the two ends of the U-shaped tube section (8). The two hollow sleeves (12) are respectively provided with fixing plates (13) connected to the positioning plate (11). The hollow sleeves (12) are provided with lateral locking pins (14) that can contact the fixing plates (13) and lock the hollow sleeves (12).

5. The automotive water pipe cutting-free forming mold device according to claim 4, characterized in that: The two ends of the U-shaped tube section (8) are respectively connected to pull ropes (15). The pull ropes (15) are arranged inside the hollow sleeve (12) and led out through the lateral locking pin (14) to form the core pulling operation end. When pulling the core, the operation end is pulled to remove the U-shaped tube section (8). The positioning plate (11) is provided with a collar (16) that is hollowly fitted with the two straight tube sections (9) and seals the forming cavity.

6. The automobile water pipe cutting-free forming mold device according to claim 5, characterized in that: The two straight pipe sections (9) are screwed onto the two ends of the U-shaped pipe section (8) by threads, the two hollow sleeves (12) are screwed onto the two ends of the U-shaped pipe section (8) by threads, the two fixing plates (13) are fixedly installed on the positioning plate (11) by bolts, and the two collars (16) on the positioning plate (11) are inserted into the forming cavity between the lower core (2) and the upper core (4).

7. The automotive water pipe cutting-free forming mold device according to claim 1, characterized in that: The pressure relief structure (7) includes a pressure relief channel (17) disposed in the lower core (2) and connected to the molding cavity. A secondary pressure relief channel (18) is provided on the side wall of the pressure relief channel (17) and connected thereto. A contour sealing block (19) is provided in the pressure relief channel (17) and can reciprocate and reset along the axial direction of the pressure relief channel (17). The contour sealing block (19) is used to seal the air inlet end of the secondary pressure relief channel (18). A push rod (20) connected to the contour sealing block (19) is provided in the pressure relief channel (17). A sleeve (21) is provided outside the lower core (2). An adjusting screw (22) is provided in the sleeve (21). A T-shaped positioning block (23) connected to the adjusting screw (22) is provided at the inner end of the adjusting screw (22). A compression spring (24) connected to the push rod (20) is provided on the T-shaped positioning block (23).

8. The automobile water pipe cutting-free forming mold device according to claim 7, characterized in that: The pressure relief channel (17) is provided with a sealing plate (25) for sealing the pressure relief channel (17). The push rod (20) passes through the sealing plate (25) and extends into the sleeve (21). The push rod (20) between the sealing plate (25) and the contour sealing block (19) is fitted with a return spring (26) that can elastically return. The sleeve (21) is provided with a locking pin (27) that can assist in limiting and locking the push rod (20).

9. The automobile water pipe cutting-free forming mold device according to claim 8, characterized in that: The lower core (2) is also provided with a limiting ring (28) to limit the movement of the outer end of the push rod (20); the sealing plate (25) is located on the air inlet side of the secondary pressure relief channel (18) and does not block the air outlet of the secondary pressure relief channel (18).

10. A method of using the automotive water pipe cutting-free forming mold device as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step 1: Assemble the mandrel: Place the sealing ring (10) at the connection between the straight pipe section (9) and the U-shaped pipe section (8), and screw the two straight pipe sections (9) to the two ends of the U-shaped pipe section (8) respectively to form the mandrel assembly (5). Step 2: Positioning and installation: Place the mandrel assembly (5) in the molding cavity of the lower core (2), install the positioning plate (11) and abut against the side wall of the lower core (2), screw the hollow sleeve (12) into the end of the U-shaped tube section (8), insert the collar (16) into the end of the molding cavity along with the positioning plate (11), fix the fixing plate (13) to the positioning plate (11) with bolts, insert the lateral locking pin (14) to lock the hollow sleeve (12), and lead the pull rope (15) out through the lateral locking pin (14) along the inside of the hollow sleeve (12) to form the core pulling operation end; Step 3: Pressure adjustment preset: Rotate the adjusting screw (22) to compress the clamping spring (24) through the T-shaped positioning block (23) to preset the pressure relief opening pressure, and tighten the locking pin (27) to assist in fixing the push rod (20). Step 4: Mold closing and material injection: Close the upper mold (3), and inject the molten material into the molding cavity through the small-diameter point gate at the end of the injection channel (29); Step 5: Pressure relief and pressure holding: During the injection and pressure holding process, the pressure inside the molding cavity increases, pushing the contour sealing block (19) to compress the clamping spring (24) and the return spring (26) to move backward, so that the secondary pressure relief channel (18) is open to exhaust overflow. After the pressure inside the cavity decreases, the contour sealing block (19) resets and closes the secondary pressure relief channel (18) under the action of the double spring. In this way, the pressure in the molding cavity is maintained in an automatic cycle. The outer end of the push rod (20) is limited by the limit ring (28) to prevent excessive backward movement. Step 6: Cooling and shaping: Cooling medium is introduced into the cooling injection groove (30) at the bottom of the downward core (2) to cool and shape the product in the molding cavity; Step 7: Mold opening and pouring: After cooling and solidification, the mold is opened and the upper mold (3) rises. Due to the small cross-sectional area and stress concentration at the point gate, it is automatically pulled off and the material handle is separated from the upper mold (3). Step 8: Segmented core removal: First, pull out the side locking pin (14) and disconnect the connection between the fixing plate (13) and the positioning plate (11). Unscrew the hollow sleeve (12) from the end of the U-shaped pipe section (8). Then, unscrew the two straight pipe sections (9) from the end of the U-shaped pipe section (8). Then, pull the operating end of the pull rope (15) and use the elastic deformation of the formed water pipe itself to pull the U-shaped pipe section (8) out of the water pipe. Step 9: Remove the finished product: Remove the molded car water pipe from the lower core (2). The contour sealing block (19) is reset under the action of the compression spring (24) and the return spring (26) to prepare for the next molding cycle.

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