Co-extrusion pipe manufacturing method and device and co-extrusion pipe

Abstract

The invention discloses a co-extrusion pipe manufacturing method and device and a co-extrusion pipe, and aims to at least solve the technical problem of extrusion molding of co-extrusion pipes with lines or marking lines in the prior art. According to the first aspect of the invention, the manufacturing method of the co-extrusion pipe is provided, the manufacturing method at least comprises a manufacturing state in which a first injection state and a second injection state are alternately used during manufacturing of the same co-extrusion pipe, the used manufacturing device of the co-extrusion pipe is at least provided with a marking injection channel, a co-extrusion injection channel and a forming channel, and in the first injection state, the co-extrusion injection channel is communicated with the forming channel; the first material is positioned on the outer surface of the second material when the second material is separated from the co-extrusion machine head; in the second injection state, the second material moves forwards along the outer wall of the forming channel, and when the second material is separated from the co-extrusion machine head, the second material is directly exposed on the outer surface, so that an annular mark or a point-shaped or strip-shaped mark can be formed on the surface of the co-extrusion pipe, construction is facilitated, the consistency of the appearance can be ensured after construction, marks of the mark are avoided, and the construction efficiency is improved. And the service life of the pipeline is not influenced.

Description

Technical Field

[0001] This application relates to the field of extrusion molding technology, and in particular to a method, apparatus and co-extruded tube manufacturing method. Background Technology

[0002] Co-extruded pipes are made by extruding at least two materials simultaneously. This not only creates a double or multi-layer structure, but also prevents delamination when multiple materials are mixed locally, resulting in higher pipe strength. Furthermore, the outer layer is usually made of aging-resistant materials, which can extend the service life of the pipe.

[0003] Due to transportation limitations, the length of a single pipe is finite. During pipe construction, multiple pipe sections need to be connected using connectors. Because the outer wall of the pipe is a single color, it's difficult to determine the insertion depth at the insertion point. Therefore, different pipes may be inserted into the connector at different depths during construction. Since multiple pipes are often installed side-by-side, their ends may be on different planes, requiring cutting or other operations, which inconveniences the construction process. Furthermore, insufficient insertion depth may cause the pipe to detach later, allowing rainwater or foreign objects to enter and affecting normal pipe use. Processing graduations on the outside of the pipe increases manufacturing costs, and using markers during construction increases labor costs. Therefore, the ideal method is to create co-extruded pipes with textured or marked lines during extrusion molding.

[0004] Chinese patent application CN2336949Y, entitled "Three-Layer Co-Extrusion Die Head," discloses a processing and forming device for three-layer plastic composite pipes. It consists of an extruder middle, inner, and outer layer connecting body, a die head body, a flow divider cone, middle, inner, and outer layer dies, a mandrel, and multiple flow channels within the die head. Notably, this die head features three independent flow channels, with independent material supply from each of the three extruders. The rational arrangement of the flow channel feed angles effectively overcomes the shortcomings of existing technologies, enabling the production of various three-layer composite pipes composed of materials A, B, and C. Furthermore, the thickness of each layer can be individually adjusted, improving production efficiency and enhancing the physical properties and appearance quality of the pipe. This patent primarily produces ordinary three-layer pipes, but the outer wall of the produced pipes is made of a single material, and the insertion depth cannot be directly identified by appearance. Summary of the Invention

[0005] This application provides a method, apparatus, and co-extruded tube manufacturing process to at least solve the problems of co-extruded tube extrusion molding technology with textured or marked lines in the prior art.

[0006] According to a first aspect of this application, a method for manufacturing a co-extruded tube is provided. The manufacturing process of the same co-extruded tube includes at least a manufacturing state that alternates between a first injection state and a second injection state. The co-extruded tube manufacturing apparatus used is provided with at least a marking injection channel, a co-extrusion injection channel, and a forming channel. In the first injection state, the marking injection channel injects a first material at a first speed under a first pressure, and the co-extrusion injection channel injects a second material at a second speed under a second pressure. When the second material exits the co-extrusion die head, the first material is located on the outer surface of the second material. In the second injection state, the pressure of the marking injection channel decreases or the marking injection channel is closed, causing the injection speed of the first material to decrease to zero or a certain amount of second material to be drawn in the opposite direction. The injection pressure of the co-extrusion injection channel remains constant or increases, and the injection speed of the second material in the co-extrusion injection channel increases. When the second material exits the co-extrusion die head, the second material is directly exposed on the outer surface. Alternatively, in the second injection state, the pressure of the forming channel increases, and a pressure stabilizing chamber is provided on the outside of the forming channel, allowing a portion of the first material in the forming channel to enter the pressure stabilizing chamber. The second material advances along the outer wall of the forming channel, and when the second material exits the co-extrusion die head, the second material is directly exposed on the outer surface.

[0007] Compared with the prior art, the co-extrusion tube manufacturing apparatus of this application has the following advantages: The co-extruded pipe manufactured using this method will have both a first material and a second material on its surface. That is, in the first injection state, only the first material appears on the surface of the co-extruded pipe, and in the second injection state, only the second material appears. By alternating between the first and second injection states, ring marks, dot-shaped marks, or strip-shaped marks can be formed on the surface of the co-extruded pipe. When connecting different pipes, the insertion depth can be identified by the ring marks, dot-shaped marks, or strip-shaped marks when inserted into the connector. There is no need to manufacture separate marks. The dot-shaped marked area can be completely inserted into the connector, so it does not affect the normal use of the co-extruded pipe at all. After construction, the appearance can be guaranteed to be consistent, there will be no marks, and the service life of the pipe will not be affected.

[0008] In one embodiment, a negative pressure backflow structure is provided in the marking injection channel. In the second injection state, the negative pressure backflow structure provides negative pressure so that a portion of the second material can enter the marking injection channel. In the first injection state, the negative pressure backflow structure provides positive pressure to push the first material and the second material in the marking injection channel to move along the injection direction. The negative pressure backflow structure can interrupt the delivery of the first material, and the positive pressure backflow structure can deliver the first material, so that the first material and the second material are distributed at intervals on the surface of the pipe.

[0009] In one embodiment, a valve structure is provided in the marked injection channel. In the second injection state, the valve structure closes the channel and the injection speed of the first material drops to zero. In the first injection state, the valve structure opens the channel and the injection speed of the first material resumes. In this way, the first material can be delivered intermittently, so that the first material and the second material are distributed at intervals on the surface of the pipe.

[0010] According to a second aspect of this application, a co-extrusion tube manufacturing apparatus is provided, including a co-extrusion die head, a first injection molding machine, and a second injection molding machine. The co-extrusion die head is provided with a mandrel, an outer die, an outer runner ring, an inner runner ring, a first interface, a second interface, and a frame. The first injection molding machine is connected to the first interface, and the second injection molding machine is connected to the second interface. A forming channel is formed between the mandrel and the outer die. A marking injection channel is formed between the inner runner ring and the outer runner ring. A co-extrusion injection channel is formed between the inner runner ring and the frame. The marking injection channel communicates with the first interface, and the co-extrusion injection channel communicates with the second interface. The forming channel and the marking injection channel are connected. The marking injection channel is connected to the co-extrusion injection channel. The marking injection channel is equipped with a valve structure or a negative pressure retraction structure. The valve structure controls the flow of the first material in the marking injection channel or molding channel. Alternatively, the molding channel is equipped with a positive pressure propulsion structure and a pressure stabilizing chamber. The pressure stabilizing chamber is located on the side close to the marking injection channel. The positive pressure propulsion structure can be an injection machine, i.e., increasing the injection pressure of the injection machine, or other piston structures that can increase the pressure in the molding channel. After pressurization, the first material enters the pressure stabilizing chamber, allowing the second material to be exposed on the surface, thus achieving the interval marking function. The valve structure or negative pressure retraction structure can also interrupt the supply of the first material to achieve the marking function.

[0011] In one embodiment, a connecting cavity is provided between the marking injection channel and the molding channel. The connecting cavity is annular, and an annular piston is provided axially within the connecting cavity. When the annular piston moves axially, it increases the volume of the connecting cavity, thereby generating negative pressure. The annular mark is easier to identify than the bar mark, and the negative pressure can change the flow direction of the first material.

[0012] In one embodiment, the connecting cavity is located on the outer end face of the inner flow channel ring. The annular piston and the inner flow channel ring are arranged axially. When the annular piston moves towards the inner flow channel ring and its first end face contacts the outer end face of the inner flow channel, the connecting cavity is closed, i.e., the marking injection channel is closed. When the annular piston moves away from the inner flow channel ring and its first end face no longer contacts the outer end face of the inner flow channel, the connecting cavity is opened, i.e., the marking injection channel is opened. The flow of the first material is controlled by the valve structure to form an annular mark.

[0013] In one embodiment, the pressure stabilizing chamber is provided with a tubular piston and an elastic reset member. After the elastic reset member is compressed to a certain length, it is installed in the pressure stabilizing chamber to push the tubular piston to stay in a position close to the marking injection channel. When the pressure of the forming channel on the tubular piston exceeds a certain range, it can push the tubular piston to move. In this way, the formed marking ring has a more regular shape and higher precision.

[0014] In one embodiment, the core mold is provided with a first driving part, which is connected to a first driving component to achieve unidirectional rotation or small-angle back-and-forth rotation, thus facilitating the processing of spiral grooves or wavy grooves inside the co-extruded tube.

[0015] In one embodiment, the co-extrusion tube manufacturing apparatus is further provided with a third pair of interfaces, a third injection machine, and a core flow channel ring. The third injection machine is connected to the third pair of interfaces, a co-extrusion injection channel is formed between the core flow channel ring and the inner flow channel ring, a grooved injection channel is formed between the core flow channel ring and the frame, the grooved injection channel is connected to the third pair of interfaces, and the forming channel is connected to the grooved injection channel, thus enabling the processing of three-layer co-extrusion tubes.

[0016] According to a third aspect of this application, a co-extruded tube is provided, manufactured using the method or apparatus described above.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0018] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, wherein: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0019] Figure 1 A schematic diagram of the composition of the co-extrusion tube manufacturing apparatus according to Embodiment 1 of this application is shown; Figure 2 A rear view schematic diagram of the co-extruded tube manufacturing apparatus according to Embodiment 1 of this application is shown; Figure 3 It shows Figure 2 A half-section diagram at point AA in the middle; Figure 4 It shows Figure 2 A half-section diagram at point BB; Figure 5 A schematic diagram of the internal structure of the co-extruded tube manufacturing apparatus according to Embodiment 1 of this application is shown; Figure 6A schematic diagram of the rear outer mold and annular piston of the co-extrusion tube manufacturing apparatus of Embodiment 1 of this application is shown; Figure 7 A schematic diagram of the rear outer mold of the co-extrusion tube manufacturing apparatus according to Embodiment 1 of this application is shown; Figure 8 It shows Figure 3 Enlarged view of a portion of point E in the middle; Figure 9 This diagram shows a partially enlarged view of point E under negative pressure conditions generated by the annular piston. Figure 10 A perspective view of the co-extrusion tube manufacturing apparatus of Embodiment 2 of this application is shown; Figure 11 A rear view schematic diagram of the co-extrusion tube manufacturing apparatus according to Embodiment 2 of this application is shown; Figure 12 It shows Figure 11 A half-section diagram at point CC; Figure 13 The co-extrusion tube manufacturing apparatus under normal pressure is shown. Figure 11 A half-section diagram at point DD; Figure 14 The co-extrusion tube manufacturing apparatus is shown under pressure. Figure 11 A half-section diagram at point DD; Figure 15 It shows Figure 14 Enlarged view of a portion of point F in the middle; Figure 16 A three-dimensional schematic diagram of the co-extruded tube according to Embodiment 3 of this application is shown; Figure 17 A half-sectional schematic diagram of the co-extruded tube of Embodiment 3 of this application is shown; Figure 18 A half-sectional schematic diagram of the co-extruded tube according to Embodiment 4 of this application is shown; Figure 19 A three-dimensional schematic diagram of the co-extruded tube according to Embodiment 5 of this application is shown; Figure 20 A half-sectional schematic diagram of the co-extruded tube of Embodiment 5 of this application is shown; Figure 21 A three-dimensional schematic diagram of the co-extruded tube according to Embodiment 6 of this application is shown; Figure 22 A three-dimensional schematic diagram of the co-extruded tube of Embodiment 7 of this application is shown.

[0020] Explanation of the labels in the diagram: X, first direction; Y, second direction; Z, third direction; 1. Core mold; 2. Outer mold; 3. Outer runner ring; 4. Inner runner ring; 5. Core runner ring; 6. Frame; 7. First pair of interfaces; 8. Second pair of interfaces; 9. Third pair of interfaces; 10. Threaded connector; 11. Molding channel; 12. Co-extrusion injection channel; 13. Marking injection channel; 14. Groove injection channel; 15. Valve structure; 16. Negative pressure return structure; 17. Positive pressure propulsion structure; 18. Pressure stabilizing chamber; 19. Outer core mold; 20. Inner core mold; 21. Front outer mold; 22. Rear outer mold; 23. Connecting cavity; 24. Annular piston; 25. Annular part; 26. Transmission part; 27. External thread; 28. Threaded sleeve; 29. ​​Bevel gear; 30. Protective shell; 31. Cavity; 32. Annular cavity; 33. First driving part; 34. First driving component; 35. First material; 36. Third material; 37. Second material; 38. Tapered segment; 39. Tubular piston; 40. Elastic reset component; 41. Small protrusion; 141. Marking layer; 142. Co-extruded layer; 143. Groove layer; 144. End surface; 145. Substrate ring; 146. Marking ring; 147. Transition ring; 148. First annular region; 149. Second annular region; 150. Straight groove; 151. Wavy groove; 152. Spiral groove; 153. Marking point; 154. Cutting area; 155. Marking reference cutting end; 156. Length reference cutting end. Detailed Implementation

[0021] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Example 1: refer to Figure 1 , Figure 2 , Figure 3 and Figure 4A co-extrusion tube manufacturing apparatus, mainly for forming three-layer co-extrusion tubes. For forming two-layer co-extrusion tubes, one injection molding machine can be shut down. If only two-layer co-extrusion tubes are produced, the core flow channel ring 5 and the third pair of interfaces 9 are not required. The co-extrusion tube manufacturing apparatus of this embodiment includes a co-extrusion die head, a first injection molding machine, a second injection molding machine, and a third injection molding machine. The first, second, and third injection molding machines are purchased ordinary injection molding machines and are therefore not shown. The injection speeds of the first, second, and third injection molding machines are related to the size and thickness of the co-extruded tube. The co-extrusion die head is provided with a core mold 1, an outer mold 2, an outer runner ring 3, an inner runner ring 4, a core runner ring 5, a first coupling 7, a second coupling 8, a third coupling 9, and a frame 6. The first coupling 7, second coupling 8, and third coupling 9 are each provided with threaded holes. The first coupling 7 is located in the third direction or at a certain angle to the third direction. The second coupling 8 is located in the first direction, and the third coupling 9 is located in the second direction. The first injection molding machine connects to the first coupling 7 via a threaded coupling pipe 10, the second injection molding machine connects to the second coupling 8 via the threaded coupling pipe 10, and the third injection molding machine connects to the third coupling pipe via the threaded coupling pipe 10. 9. A forming channel 11 is formed between the core mold 1 and the outer mold 2. A marking injection channel 13 is formed between the inner flow channel ring 4 and the outer flow channel ring 3. A co-extrusion injection channel 12 is formed between the inner flow channel ring 4 and the core flow channel ring 5. A grooved injection channel 14 is formed between the core flow channel ring 5 and the frame 6. The marking injection channel 13 is connected to the first pair of interfaces 7. The co-extrusion injection channel 12 is connected to the second pair of interfaces 8. The grooved injection channel 14 is connected to the third pair of interfaces 9. The forming channel 11 is connected to the marking injection channel 13, the grooved injection channel 14, and the co-extrusion injection channel 12. The marking injection channel 13 is equipped with a valve structure 15 or a negative pressure backflow structure 16. The valve structure 15 controls the flow of the first material in the marking injection channel 13 or the forming channel 11. Alternatively, the forming channel 11 is equipped with a positive pressure propulsion structure 17 and a pressure stabilizing chamber 18. The pressure stabilizing chamber 18 is located on the side closer to the marking injection channel 13, and the positive pressure propulsion structure 17 is located on the side away from the marking injection channel 13. The first direction is axially upward, and the first direction, the second direction, and the third direction are perpendicular to each other. The frame 6 is equipped with multiple mounting holes for easy installation on other structures.

[0023] refer to Figure 1 , Figure 3 and Figure 4To facilitate processing and installation, and to form co-extruded tubes of different sizes, the outer mold 2 includes a front outer mold 21 and a rear outer mold 22, which are arranged along a first direction. For ease of processing, the main structure of the front outer mold 21 and the rear outer mold 22 is a rotating structure. The core mold 1 includes an outer core mold 19 and an inner core mold 20, with the outer core mold 19 fitted onto the inner core mold 20. Different inner core molds 20 and front outer molds 21 can be used to produce different types of co-extruded tubes. In some embodiments, the inner core mold 20 needs to be able to rotate relative to the outer core mold 19; therefore, the inner core mold 20 passes through the center hole of the frame 6 and has a drive structure at its end. Biaxial orientation requires axial and circumferential stretching of the tube blank; therefore, the forming channel 11 between the outer mold 2 and the core mold 1 is partially tapered.

[0024] refer to Figure 1 , Figure 3 and Figure 5 The outer flow channel ring 3, inner flow channel ring 4, core flow channel ring 5 and frame 6 all adopt a rotating body structure. The outer flow channel ring 3, inner flow channel ring 4 and core flow channel ring 5 are designed as tubular rings, which are sequentially nested and fixed on the frame 6. In order to stabilize the distribution of materials in different directions, the inner flow channel ring 4, core flow channel ring 5 and frame 6 are machined with threaded grooves or raised threaded structures to form annular marked injection channels 13, grooved injection channels 14 and co-extrusion injection channels 12, which guide the material to flow in annular shape.

[0025] like Figure 3 and Figure 4 As shown, in one embodiment, a connecting cavity 23 is provided between the marking injection channel 13 and the molding channel 11. The connecting cavity 23 is annular, and an annular piston 24 is provided axially in the connecting cavity 23. When the annular piston 24 moves axially, it increases the volume of the connecting cavity 23, which can generate negative pressure. The valve structure 15 and the negative pressure retraction structure 16 can be an integral structure, namely the annular piston 24 structure.

[0026] like Figure 3 and Figure 4 As shown, in one embodiment, the connecting cavity 23 is located on the outer end face of the inner flow channel ring 4. The annular piston 24 and the inner flow channel ring 4 are arranged axially. When the annular piston 24 moves towards the inner flow channel ring 4 and its first end face contacts the outer end face of the inner flow channel, the connecting cavity 23 is closed, i.e., the marked injection channel 13 is closed. When the annular piston 24 moves away from the inner flow channel ring 4 and its first end face does not contact the outer end face of the inner flow channel, the connecting cavity 23 is opened, i.e., the marked injection channel 13 is opened. The annular piston 24 can achieve linear movement by means of a hydraulic cylinder, a gear and rack, a worm gear structure, or a cam.

[0027] like Figure 5 and Figure 6As shown, in one embodiment, the annular piston 24 includes an annular portion 25 and a transmission portion 26. The transmission portion 26 has multiple threads extending axially from the annular portion 25. A portion of the transmission portion 26 has external threads 27, which mate with a threaded sleeve 28. The threaded sleeve 28 is driven to rotate by a second driving member. The second driving member is a bevel gear 29, which rotates directly or indirectly via a geared motor or a hydraulic motor. The forward and reverse rotation of the bevel gear 29 corresponds to the forward and reverse axial movement of the annular piston 24. Figure 4 As shown, to limit the position of the bevel gear 29, a first bearing and a second bearing are provided to limit the axial position of the bevel gear 29, so that the bevel gear 29 provides an axial force to the annular piston 24. A protective shell 30 is provided outside the bevel gear 29. Figure 6 and Figure 7 As shown, the rear outer mold 22 is provided with an annular cavity 32 and a bore cavity 31. The annular cavity 32 can accommodate the annular part 25 of the annular piston 24, and the bore cavity 31 can accommodate the transmission part 26.

[0028] like Figure 1 and Figure 4 As shown, in one embodiment, the core mold 1 is provided with a first driving part 33, which is connected to a first driving member 34 to achieve unidirectional rotation or small-angle back-and-forth rotation. The core mold 1 is provided with small protrusions 41 for processing grooves on the inner wall of the co-extruded tube, which can process straight, spiral, and wavy grooves. refer to Figure 3 and Figure 4 A method for manufacturing a co-extruded tube includes at least two alternating injection states during the manufacturing of the same co-extruded tube. The co-extruded tube manufacturing apparatus is equipped with at least a marking injection channel 13 and a co-extrusion injection channel 12. In the first injection state, the marking injection channel 13 injects a first material 35 at a first speed under a first pressure, and the co-extrusion injection channel 12 injects a second material 37 at a second speed under a second pressure. When the second material 37 exits the co-extrusion die head, the first material 35 is located on the outer surface of the second material 37. In the second injection state, the pressure of the marking injection channel 13 decreases or the marking injection channel 13 is closed, causing the injection speed of the first material 35 to decrease to zero or to draw in a certain amount of the second material 37 in the reverse direction. The injection pressure of the co-extrusion injection channel 12 remains unchanged or increases, and the injection speed of the second material 37 in the co-extrusion injection channel 12 increases. When the second material 37 exits the co-extrusion die head, the second material 37 is directly exposed on the outer surface. The first pressure is provided by the first injection machine, and the second pressure is provided by the second injection machine. When manufacturing a three-layer tube, a third injection machine is also provided, which provides a third material 36.

[0029] like Figure 9As shown, in one possible embodiment, a negative pressure retraction structure 16, i.e., an annular piston 24, is provided in the marking injection channel 13. In the second injection state, the negative pressure retraction structure 16 provides negative pressure, allowing a portion of the second material 37 to enter the marking injection channel 13, such as... Figure 8 As shown, in the first injection state, the negative pressure backflow structure 16 provides positive pressure to push the first material 35 and the second material 37 of the marked injection channel 13 to move along the injection direction.

[0030] like Figure 4 As shown, in one possible embodiment, a valve structure 15 is provided in the marked injection channel 13. In the second injection state, the valve structure 15 closes the channel, and the injection speed of the first material 35 drops to zero. Figure 3 As shown, in the first injection state, the valve structure 15 opens the channel, and the first material 35 resumes the injection speed.

[0031] Example 2: refer to Figure 10 , Figure 11 , Figure 12 and Figure 13 The difference from Embodiment 1 is that the molding channel 11 is provided with a positive pressure propulsion structure 17 and a pressure stabilizing chamber 18. The pressure stabilizing chamber 18 is located on the side of the outer mold 21 near the molding channel 11, and the positive pressure propulsion structure 17 is located on the side of the inner core mold 20 near the molding channel 11. The positive pressure propulsion structure 17 can be provided with a separate pressurizing device, or pressurization can be achieved using an injection molding machine. Alternatively, it can be formed using an outer core mold 19 and an inner core mold 20, with the outer core mold 19 fitted onto the inner core mold 20. The inner core mold 20 is provided with a tapered section 38. When the tapered section 38 moves along the first direction, it can increase the volume of the molding channel 11 to achieve pressure reduction. When the tapered section 38 moves in the opposite direction to the first direction, it can decrease the volume of the molding channel 11 to achieve pressure increase.

[0032] like Figure 13 and Figure 14 As shown, the pressure stabilizing chamber 18 is equipped with a tubular piston 39 and an elastic reset member 40. After being compressed to a certain length, the elastic reset member 40 is installed in the pressure stabilizing chamber 18 to push the tubular piston 39 to remain in a position close to the marking injection channel 13. When the pressure of the molding channel 11 on the tubular piston 39 exceeds a certain range, it can push the tubular piston 39 to move.

[0033] A method for manufacturing co-extruded tubes includes at least two manufacturing states during the manufacturing of the same co-extruded tube, alternating between a first injection state and a second injection state. The co-extruded tube manufacturing apparatus used is equipped with at least a marking injection channel 13, a co-extrusion injection channel 12, and a forming channel 11. Figure 13As shown, in the first injection state, the marked injection channel 13 injects the first material 35 at a first speed under the first pressure, and the co-extrusion injection channel 12 injects the second material 37 at a second speed under the second pressure. When the second material 37 detaches from the co-extrusion die head, the first material 35 is located on the outer surface of the second material 37; as shown... Figure 14 and Figure 15 As shown, in the second injection state, the pressure in the molding channel 11 increases. A pressure stabilizing chamber 18 is provided on the outside of the molding channel 11, allowing a portion of the first material 35 in the molding channel 11 to enter the pressure stabilizing chamber 18. That is, the first material 35 does not enter the molding channel 11 within a certain area, while the second material 37 advances along the outer wall of the molding channel 11. When the second material 37 detaches from the co-extrusion die head, the second material 37 is directly exposed on the outer surface. The pressure in the molding channel 11 can be controlled by the inner mandrel 20 moving towards the molding channel 11.

[0034] Example 3: like Figure 16 and Figure 17 As shown, a co-extruded tube is manufactured using the method or apparatus of Example 1 or 2.

[0035] like Figure 16 and Figure 17 As shown, the three-layer co-extruded tube includes a marking layer 141, a co-extruded layer 142, and a grooved layer 143. The marking layer 141 covers the co-extruded layer 142. The marking layer 141 is extruded using a first material 35 and a second material 37. The first material 35 and the second material 37 have different colors. The first material 35 and the second material 37 are spaced apart along the axial direction of the co-extruded tube at least on the end surface 144 of the co-extruded tube. The junction of the first material 35 and the second material 37 has a junction line or transition area, which is a junction line or transition area naturally formed by different colored materials. The grooved layer 143 is located inside the co-extruded layer 142. The co-extruded layer 142 is made of the second material 37, and the grooved layer 143 is made of the third material.

[0036] like Figure 16 and Figure 17 As shown, in one embodiment, the marking layer 141 is provided with a substrate ring 145, and the substrate ring 145 and the co-extruded layer 142 are made of the same second material 37.

[0037] like Figure 16 and Figure 17 As shown, in one embodiment, the marking layer 141 is provided with a marking ring 146, which is extruded from a first material 35.

[0038] like Figure 16 and Figure 17As shown, in one embodiment, the marking layer 141 includes a first annular region 148 and a second annular region 149. The number of marking rings 146 in the first annular region 148 is different from the number of marking rings 146 in the second annular region 149. The marking layer 141 mainly covers the first material 35, and the second material 37 forms five annular structures, that is, three at the upper end and two at the lower end. In one embodiment, the different widths of the upper and lower marking rings 146 make the overall width of the marking area the same.

[0039] like Figure 16 and Figure 17 As shown, in one embodiment, the groove layer 143 is provided with straight grooves 150, which are evenly distributed on the inner wall of the three-layer co-extruded tube.

[0040] like Figure 17 As shown, in one embodiment, the marking ring 146 has a triangular cross-section.

[0041] JT-HPO pipe is a high-strength, aging-resistant three-layer oriented co-extruded pipe. Its core is a three-layer co-extruded structure: the outer layer blocks environmental corrosion, the middle layer provides structural support, and the inner layer optimizes cable-laying performance. These three layers work together to achieve integrated protection, strength, and function, overcoming the shortcomings of traditional single-layer pipes that excel in only one specific performance characteristic but lack comprehensive overall performance. The material and process parameters for each layer are as follows: Preparation of Marking Layer 141: The first material 35 is a UV-resistant composite polymer resin (with added nano-level antioxidants and UV absorbers). After being melted in a co-extrusion machine, it is coated on the outside of the co-extruded layer 142 with a thickness of 1.5-3.0 mm. A nano-dispersion process is used to ensure uniform distribution of additives. After cooling, a purple outer protective layer is formed. The color change level is ≥4 and the tensile retention rate is ≥95%. Compared with traditional pipes, the aging resistance life is extended by more than 3 times. It can adapt to low temperature to high temperature environments from -30℃. There is no performance degradation under strong acid and alkali and ultraviolet radiation. The cable length is increased by 50%, the number of inspection wells used is reduced by 30%, and the construction cost is reduced.

[0042] Preparation of co-extruded layer 142: The second material 37 is a mixed material, in which high-performance PVC resin and CPVC resin are mixed in a ratio of 9:1 to 7:3, with the addition of modifiers, toughening agents, and stabilizers. The mixture is melted in a twin-screw extruder to form a pipe blank. The pipe blank is then subjected to axial and circumferential stretching (stretch ratio 1:2.5) using a biaxial orientation device to form a molecular network structure. After cooling, the wall thickness of the intermediate layer is controlled at 2.0-10.0 mm (adjusted according to the nominal outer diameter). The ring stiffness is tested to be ≥10-50 KN / ㎡, and the Vicat softening temperature is ≥93℃ for Type I, ≥105℃ for Type II, ≥120℃ for Type III, and ≥135℃ for Type IV. The maximum ring stiffness reaches 50 KN / ㎡, and the tensile strength is ≥45 MPa (circumferential) and ≥52 MPa (longitudinal). Impact resistance is improved by 10 times, preventing pipe wall brittleness. Material savings exceed 20%, and energy consumption and carbon emissions are reduced by 15%, meeting the requirements of green and sustainable development.

[0043] Fabrication of Cable Tray Layer 143: The silicon core layer is processed on the inner wall of the cable tray layer 143 using a laser etching machine (50W power, 0.05mm etching depth). After etching, the static friction coefficient of the inner wall is ≤0.2. After three-layer co-extrusion molding, it is processed into a flared plug-in structure by a flaring machine, or it can be directly plugged in. The length is cut into 6m, 9m, or 12m specifications. This significantly reduces cable pulling resistance, eliminates the risk of cable scratches, allows a single person to complete long-distance cable pulling operations, and improves construction efficiency by 40%. The silicon core layer is tightly bonded to the pipe body, and its service life is synchronized with the pipe body, eliminating subsequent maintenance costs.

[0044] The marking layer 141 achieves a color change level ≥4 and a tensile retention rate ≥95% through optimized formulation of composite polymer materials; the intermediate layer improves ring stiffness by 50%, tensile strength by 50%, Vicat softening temperature by 20%-30%, and impact resistance by more than 10 times through biaxial orientation process; the inner silicon core layer reduces the coefficient of friction by 80% through precise control of surface roughness by laser etching.

[0045] For highway cable laying, JT-HPO pipes with a nominal outer diameter of 110mm and a wall thickness of 4.9mm (ring stiffness ≥32KN / ㎡) are selected. They are directly buried underground using plug-in connections. The cables are lightweight, easy to handle, and easy to connect, requiring no mechanical assistance and reducing construction costs. The low friction coefficient of the inner layer ensures a single cable length of up to 100m, eliminating the need for additional inspection wells. The UV-resistant surface layer prevents aging issues associated with open-air laying, while the high-strength middle layer withstands soil pressure from vehicle traffic.

[0046] Example 4: like Figure 18As shown, the difference from Embodiment 3 is that the groove layer 143 is provided with corrugated grooves 151, which are evenly distributed on the inner wall of the three-layer co-extruded tube. In one embodiment, the marking ring 146 has a semi-circular waist-groove cross-section, which facilitates molding.

[0047] Example 5: like Figure 19 and Figure 20 As shown, the difference from Embodiment 3 is that the groove layer 143 is provided with spiral grooves 152, which are evenly distributed on the inner wall of the three-layer co-extruded tube. In one embodiment, the marking ring 146 has a rectangular cross-section. Figure 19 As shown, in one embodiment, a transition ring 147 is provided between the substrate ring 145 and the marking ring 146.

[0048] Example 6: like Figure 21 As shown, the difference from Example 3 is that the marking ring 146 is not set, but the marking point 153 is set. The marking point 153 is made of different materials co-extruded on the outside of the pipe wall, and the material can be fed intermittently.

[0049] Example 7: like Figure 22 As shown, the difference from Embodiment 3 is that the co-extruded tube is provided with a cutting area 154, which is provided with a marking reference cutting end 155 and a length reference cutting end 156. That is, cutting is first performed according to the position of the marking ring 146. The position of the marking ring 146 can be automatically identified by an artificial intelligence image or color recognition device to cut the marking reference cutting end 155, or it can be cut manually. Then, the length reference cutting end 156 is cut according to the length. This ensures that the position of the marking ring 146 is more accurate and that the co-extruded tube has the same length.

[0050] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0052] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of manufacturing a co-extruded tube, characterized by, At least including manufacturing state of first injection state and second injection state alternately used when manufacturing the same co-extrusion tube, and using co-extrusion tube manufacturing device at least setting mark injection channel (13), co-extrusion injection channel (12) and forming channel (11), in the first injection state, the mark injection channel (13) is injected with the first material (35) at the first speed under the action of the first pressure, the co-extrusion injection channel (12) is injected with the second material (37) at the second injection speed under the action of the second pressure, and the first material (35) is located on the outer surface of the second material (37) when the second material (37) is separated from the co-extrusion head; In the second injection state, the mark injection channel (13) is lowered or closed under the pressure of the mark injection channel (13), so that the injection speed of the first material (35) is lowered to zero or a certain second material (37) is sucked reversely, the injection pressure of the co-extrusion injection channel (12) is maintained or increased, the injection speed of the second material (37) of the co-extrusion injection channel (12) is increased, and the second material (37) is directly exposed on the outer surface when the second material (37) is separated from the co-extrusion head; Or, in the second injection state, the pressure of the forming channel (11) is increased, the forming channel (11) is provided with a pressure stabilizing cavity (18) outside the forming channel (11), so that part of the first material (35) in the forming channel (11) enters the pressure stabilizing cavity (18), the second material (37) advances along the outer wall of the forming channel (11), and the second material (37) is directly exposed on the outer surface when the second material (37) is separated from the co-extrusion head.

2. The co-extruded pipe manufacturing method according to claim 1, characterized in that, The mark injection channel (13) is provided with a negative pressure backflow structure (16), which provides negative pressure in the second injection state so that part of the second material (37) can enter the mark injection channel (13), and provides positive pressure in the first injection state to push the first material (35) and the second material (37) in the mark injection channel (13) to move in the injection direction.

3. The co-extruded pipe manufacturing method according to claim 1, characterized in that, The mark injection channel (13) is provided with a valve structure (15), which is closed in the second injection state, and the injection speed of the first material (35) is lowered to zero, and in the first injection state, the valve structure (15) is opened, and the injection speed of the first material (35) is restored.

4. A co-extrusion pipe manufacturing device, comprising a co-extrusion head, a first injection machine and a second injection machine, the co-extrusion head is provided with a core mold (1), an outer mold (2), an outer runner ring (3), an inner runner ring (4), a first docking interface (7), a second docking interface (8) and a frame (6), the first injection machine is docked with the first docking interface (7), the second injection machine is docked with the second docking interface (8), a forming channel (11) is formed between the core mold (1) and the outer mold (2), a marking injection channel (13) is formed between the inner runner ring (4) and the outer runner ring (3), a co-extrusion injection channel (12) is formed between the inner runner ring (4) and the frame (6), the marking injection channel (13) is communicated with the first docking interface (7), the co-extrusion injection channel (12) is communicated with the second docking interface (8), the forming channel (11) is communicated with the marking injection channel (13) and the co-extrusion injection channel (12), the marking injection channel (13) is provided with a valve structure (15) or a negative pressure backflow structure (16), the valve structure (15) controls the flow of the first material (35) in the marking injection channel (13) or the forming channel (11); or the forming channel (11) is provided with a pressure stabilizing cavity (18), the pressure stabilizing cavity (18) is arranged on the side close to the marking injection channel (13).

5. The co-extrusion pipe manufacturing apparatus according to claim 4, wherein a connecting cavity (23) is arranged between the marking injection channel (13) and the forming channel (11), the connecting cavity (23) is annular, an annular piston (24) is arranged in the connecting cavity (23) in the axial direction, and the negative pressure is generated by increasing the volume of the connecting cavity (23) when the annular piston (24) moves in the axial direction.

6. The co-extrusion pipe manufacturing apparatus according to claim 5, wherein the connecting cavity (23) is located on the outer end surface of the inner runner ring (4), the annular piston (24) is arranged in the axial direction of the inner runner ring (4), when the annular piston (24) moves towards the inner runner ring (4) and the first end surface of the annular piston (24) contacts the outer end surface of the inner runner ring (4), the connecting cavity (23) is closed, that is, the marking injection channel (13) is closed, when the annular piston (24) moves away from the inner runner ring (4) and the first end surface of the annular piston (24) does not contact the outer end surface of the inner runner ring (4), the connecting cavity (23) is opened, that is, the marking injection channel (13) is opened.

7. The co-extrusion pipe manufacturing apparatus according to claim 4, wherein the pressure stabilizing cavity (18) is provided with a tubular piston (39) and an elastic reset member (40), the elastic reset member (40) is compressed by a certain length and installed in the pressure stabilizing cavity (18) to push the tubular piston (39) to stay close to the marking injection channel (13), when the pressure of the forming channel (11) on the tubular piston (39) exceeds a certain range, the tubular piston (39) can be pushed to move.

8. The co-extrusion pipe manufacturing apparatus according to claim 7, characterized by the core mold (1) is provided with a first driving part (33), the first driving part (33) is connected with a first driving member (34) to realize one-way rotation or back-and-forth small-angle rotation.

9. The co-extrusion pipe manufacturing apparatus according to claim 8, wherein The co-extrusion pipe manufacturing device is further provided with a third interface (9), a third injection machine and a core flow channel ring (5), the third injection machine is in butt joint with the third interface (9), the core flow channel ring (5) and the inner flow channel ring (4) form the co-extrusion injection channel (12), the core flow channel ring (5) and the rack (6) form the wire slot injection channel (14), the wire slot injection channel (14) is communicated with the third interface (9), and the forming channel (11) is communicated with the wire slot injection channel (14).

10. A co-extruded tube characterized in that, The co-extrusion pipe manufacturing device is manufactured by using the co-extrusion pipe manufacturing method in claim 1, 2 or 3 or any one of claims 4-9.

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