Coating mold for producing PSP steel-plastic composite pressure pipe with double-layer structure

Abstract

The invention relates to the technical field of PSP steel-plastic composite pressure pipe production, in particular to a coating mold for PSP steel-plastic composite pressure pipe production with a double-layer structure. The device comprises an inner pipe shaping piece and an outer pipe shaping piece. In the invention, a plastic pipe raw material flows along the outer wall of the first inner mold assembly to form an inner-layer plastic pipe blank; the sizing material flows along the inner wall of the first outer mold assembly, is smeared on the outer wall of the inner-layer plastic pipe blank, and is extruded from the inner-layer extrusion cavity to obtain an inner-layer plastic pipe of which the outer wall is coated with the sizing material; the plastic pipe raw material flows along the inner wall of the second outer mold assembly to form an outer-layer plastic pipe blank; a sizing material flows along the outer wall of the second inner mold assembly and is smeared on the inner wall of an outer-layer plastic pipe blank, then the outer-layer plastic pipe with the inner wall coated with the sizing material is obtained through extrusion of the outer-layer extrusion cavity, the outer-layer plastic pipe inlet channel wraps the outer wall of the composite steel pipe, the production process is simplified, the number of used equipment is reduced, and the production efficiency is improved. Therefore, the production cost of the PSP steel-plastic composite pressure pipe is reduced, and the product bonding quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of composite pressure pipe production, in particular to a coating mould for producing a PSP steel-plastic composite pressure pipe with a double-layer structure. Background Art

[0002] PSP steel-plastic composite pressure pipes are made from a composite of metals such as steel and aluminum and thermoplastics such as polyethylene and polypropylene. They combine the high strength of metal with the corrosion resistance of plastic. Their typical structure includes a metal reinforcement layer, a hot-melt adhesive layer, and inner and outer plastic layers, making them suitable for transporting fluids under pressure.

[0003] Composite pressure pipes include steel-plastic composite pressure pipes, aluminum-plastic composite pressure pipes and bimetallic composite pressure pipes. Among them, the existing production process of steel-plastic composite pressure pipes generally uses welded steel pipes as the middle layer, and sets plastic materials such as polyethylene or polypropylene on the inner and outer layers, which are compounded with special hot melt adhesives. The specific process is as follows Figure 1 As shown, the production process is as follows:

[0004] First, an inner plastic tube is obtained by extrusion, and then an inner rubber layer is coated on the surface of the inner plastic tube. After the steel strip or steel plate is rolled into shape and welded to obtain a steel tube, the inner plastic tube is placed in the steel tube, and the inner rubber layer is bonded and solidified to the inner wall of the steel tube by heating, and the inner plastic tube is bonded and fixed to the inner wall of the steel tube; then an outer rubber layer is coated on the outer wall of the steel tube, and an outer plastic tube is extruded and coated on the outer rubber layer. Finally, it is subjected to heat treatment to solidify the outer rubber layer, and the outer plastic tube is bonded and fixed to the outer wall of the steel tube to obtain a steel-plastic composite pressure tube.

[0005] In the above process, there are multiple independent steps such as extruding the inner plastic pipe, applying the inner rubber layer, coiling and welding the steel pipe, assembling the inner pipe, heating and curing the inner rubber layer, applying the outer rubber layer, extruding the outer plastic pipe and secondary heating and curing, which makes the process complicated and the number of equipment used is large, making the production cost of the composite pressure pipe high. Summary of the Invention

[0006] The purpose of the present invention is to merge the process steps of PSP steel-plastic composite pressure pipe to simplify the production process of composite pressure pipe, thereby reducing the production cost of PSP steel-plastic composite pressure pipe and improving product quality.

[0007] The purpose of the present invention is to provide a covering mold for the production of PSP steel-plastic composite pressure pipes with a double-layer structure. By combining the steps of extruding inner / outer plastic pipes with the steps of coating inner / outer rubber layers, that is, simultaneously performing plastic pipe extrusion and rubber layer coating to reduce the independent steps in the process, the production process is simplified, and the production cost of PSP steel-plastic composite pressure pipes is reduced and the product quality is improved.

[0008] To achieve the above object, the present invention provides a coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure, comprising an inner pipe molding part and an outer pipe molding part;

[0009] The inner tube shaping part includes a double-layer feeding structure, a first inner mold assembly and a first outer mold assembly, wherein the first inner mold assembly is located inside the first outer mold assembly, and the central axis of the first inner mold assembly coincides with the central axis of the first outer mold assembly, and the outer wall of the first inner mold assembly cooperates with the inner wall of the first outer mold assembly to form an inner layer extrusion cavity;

[0010] One end of the double-layer feeding structure is connected to the inner layer extrusion cavity. The double-layer feeding structure is used to simultaneously inject the plastic tube raw material and the rubber material into the inner layer extrusion cavity, and then extrude them from the inner layer extrusion cavity to obtain an inner layer plastic tube with the outer wall coated with the rubber material;

[0011] The outer tube shaping member includes a hollow feed structure, a second inner mold assembly and a second outer mold assembly, wherein the second inner mold assembly is located within the second outer mold assembly, and the central axis of the second inner mold assembly coincides with the central axis of the second outer mold assembly, and the outer wall of the second inner mold assembly cooperates with the inner wall of the second outer mold assembly to form an outer extrusion cavity;

[0012] The middle of the second inner mold assembly and the second outer membrane assembly are both provided with a through opening, which is connected to the middle of the hollow feed structure to form a channel for the steel pipe to pass through, and one end of the outer layer extrusion cavity is connected to the channel;

[0013] The hollow feeding structure is connected to the other end of the outer layer extrusion cavity. The hollow feeding structure is used to inject the plastic tube raw material and the rubber into the outer layer extrusion cavity at the same time, and extrude them from the outer layer extrusion cavity to obtain an outer layer plastic tube with the inner wall coated with rubber. The outer layer extrusion cavity then covers the outer layer plastic tube on the outer wall of the steel tube.

[0014] As a further improvement of the present technical solution, the double-layer feeding structure includes an inner tube feeding channel, an inner rubber feeding channel, an inner tube spiral, an inner rubber spiral and a first spiral outer sleeve, the inner tube spiral is located in the middle of the first spiral outer sleeve, one end of the inner tube spiral is fixedly connected to the inner wall of the first spiral outer sleeve along the axial direction, the inner rubber spiral is a hollow cylinder, and the inner rubber spiral is installed between the outer wall of the inner tube spiral and the inner wall of the first spiral outer sleeve, the outer wall of the inner tube spiral and the inner wall of the inner rubber spiral cooperate to form a first compression chamber, the outer wall of the inner rubber spiral and the inner wall of the first spiral outer sleeve cooperate to form a second compression chamber, and the first compression chamber and the second compression chamber are both connected to the inner layer extrusion chamber;

[0015] The inner tube feed channel is fixedly embedded in one end of the first spiral outer sleeve, and a first material channel is opened in the inner tube spiral body. The inner tube feed channel is connected to the first material channel, and the inner tube feed channel is used to inject plastic tube raw materials, and the plastic tube raw materials flow into the first compression chamber through the first material channel;

[0016] The inner rubber feed flow channel is fixedly embedded in the side wall of the first spiral outer sleeve, and the inner rubber feed flow channel is communicated with the second compression chamber. The inner rubber feed flow channel is used to inject rubber into the second compression chamber.

[0017] The plastic tube raw material is injected into the first material channel through the inner tube feed channel, the plastic tube raw material enters the first compression chamber through the first material channel, and enters the inner layer extrusion chamber along the first compression chamber; the rubber is directly injected into the second compression chamber through the inner rubber feed channel, and then the rubber enters the inner layer extrusion chamber along the second compression chamber.

[0018] Furthermore, spiral grooves are provided on the outer walls of the inner tube spiral in the first compression chamber and the outer walls of the inner rubber spiral in the second compression chamber. After the plastic tube raw material and rubber are injected, they are axially transported along the spiral grooves in the first compression chamber and the second compression chamber respectively until they enter the inner layer extrusion chamber.

[0019] As a further improvement of the present technical solution, the first inner mold assembly includes a first core mold coaxially connected to the end of the inner tube spiral body away from the inner tube feed flow channel, and the first outer mold assembly includes a compression flange, a first mold adjustment pressure ring, a compression sleeve and a first die;

[0020] The compression flange is fixedly connected to the end surface of the first spiral sleeve, the first die-adjusting pressure ring is sleeved on one end of the compression sleeve, the first die-adjusting pressure ring is fixedly connected to the compression flange, the compression sleeve is fixedly connected to the compression flange via the first die-adjusting pressure ring, the first die-adjusting pressure ring is provided with a die-adjusting bolt for fixing the compression sleeve, and the first die is fixedly connected to the other end of the compression sleeve;

[0021] The outer wall of the first core mold cooperates with the inner wall of the compression flange, the inner wall of the compression sleeve, and the inner wall of the first die to form the inner layer extrusion cavity. The inner diameter of the compression flange is larger than the inner diameter of the compression sleeve, and the inner diameter of the first die is smaller than the inner diameter of the compression sleeve.

[0022] Furthermore, the outer wall of the inner tube spiral located in the compression flange is inclined outward, the inner wall of the compression flange is narrowed inward at a corresponding position, and the inner and outer walls of the inner rubber spiral away from the inner tube feed channel are both inclined.

[0023] The plastic tube raw material flows out along the second material channel formed by the outer inclined surface of the outer wall of the inner tube spiral and the inner wall inclined surface of the inner rubber spiral to initially form an inner layer plastic tube blank, while the rubber flows out along the third material channel formed by the outer wall inclined surface of the inner rubber spiral and the narrowing surface of the compression flange, contacts the outer wall of the inner layer plastic tube blank flowing out through the second material channel, and at the same time moves along the inner layer extrusion cavity. After the extrusion and compression treatment of the inner layer extrusion cavity, it is finally extruded from the end of the inner layer extrusion cavity to obtain an inner layer plastic tube with an outer wall evenly coated with rubber.

[0024] As a further improvement of the present technical solution, the hollow feeding structure includes an outer tube feeding channel, an outer rubber feeding channel, an outer tube spiral, an outer rubber spiral and a second spiral jacket, the outer tube spiral, the outer rubber spiral and the second spiral jacket are all hollow cylinders, and the central axes of the outer tube spiral, the outer rubber spiral and the second spiral jacket coincide with each other, the outer rubber spiral is located inside the outer tube spiral, the second spiral jacket is located outside the outer tube spiral, the inner wall of the outer tube spiral cooperates with the outer wall of the outer rubber spiral to form a third compression chamber, the outer wall of the outer tube spiral cooperates with the inner wall of the second spiral jacket to form a fourth compression chamber, and the third compression chamber and the fourth compression chamber are both connected to the outer layer extrusion chamber;

[0025] The outer tube feed flow channel is embedded in the side wall of the second spiral outer sleeve, and the outer tube feed flow channel is connected to the fourth compression chamber, and the outer tube feed flow channel is used to inject plastic tube raw materials into the fourth compression chamber;

[0026] The outer rubber feed flow channel is fixedly connected to the end surface of the second spiral outer sleeve through bolts, and the outer rubber feed flow channel is communicated with the third compression chamber. The outer rubber feed flow channel is used to inject rubber into the third compression chamber.

[0027] The third compression chamber for accommodating the rubber material is located inside the fourth compression chamber for accommodating the plastic tube raw material, so that the rubber material can be evenly applied to the inner wall of the outer plastic tube blank when flowing in the outer extrusion chamber.

[0028] As a further improvement of the present technical solution, the second inner mold assembly includes a second die fixedly connected to one end of the outer rubber spiral away from the outer rubber feed channel, the second outer mold assembly includes a compression ring, a second core mold and a second mold adjustment pressure ring, the second die and the second core mold are both provided with the through opening, and the through opening is connected to the middle part of the outer rubber spiral to form the passage for the steel pipe to pass through, one end of the compression ring is fixedly connected to the end face of the second spiral sleeve by a bolt, the second mold adjustment pressure ring is snap-fitted with one end of the second core mold, and the second mold adjustment pressure ring is fixedly connected to the other end of the compression ring by a bolt;

[0029] The outer wall of the second die cooperates with a portion of the inner wall of the second core die to form the outer extrusion cavity, and the outlet of the outer extrusion cavity is connected to the channel;

[0030] An outer wall of the outer tube spiral body at one end away from the outer rubber feed channel is provided with an inclined surface, and a corresponding position of the inner wall of the compression ring is narrowed inwardly.

[0031] The plastic tube raw material in the fourth compression chamber passes through the fourth material channel formed by the outer tube spiral inclined surface and the compression ring narrowing surface, and enters the fifth material channel formed by the outer wall of the outer rubber spiral and the inner wall of the compression ring, and initially forms the outer layer plastic tube blank. The rubber flows along the third compression chamber to the fifth material channel, contacts the inner wall of the outer layer plastic tube blank flowing out through the fourth material channel, and then passes through the inlet of the outer layer extrusion chamber at the same time and moves along the outer layer extrusion chamber. After the extrusion and compression treatment of the outer layer extrusion chamber, it is finally extruded from the outlet of the outer layer extrusion chamber to obtain an outer layer plastic tube with an inner wall evenly coated with rubber. The outer layer plastic tube then enters the channel and is coated on the outer wall of the composite steel pipe.

[0032] In the present invention, the inner tube shaping part is used to simultaneously perform the steps of forming the inner plastic tube and coating the outer wall of the inner plastic tube with rubber, and the outer tube shaping part is used to simultaneously perform the steps of forming the outer plastic tube and coating the inner wall of the outer plastic tube with rubber, thereby simplifying the production process of the steel-plastic composite pressure tube.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. In the covering mold for the production of the PSP steel-plastic composite pressure pipe with a double-layer structure, the plastic pipe raw material flows along the outer wall of the first inner mold component of the inner extrusion cavity to initially form an inner plastic pipe blank; the rubber material flows along the inner wall of the first outer mold component of the inner extrusion cavity and is evenly smeared on the outer wall of the inner plastic pipe blank, and then is extruded from the inner extrusion cavity to obtain an inner plastic pipe with an outer wall coated with rubber material; the plastic pipe raw material flows along the inner wall of the second outer mold component of the outer extrusion cavity to initially form an outer plastic pipe blank; the rubber material flows along the outer wall of the second inner mold component of the outer extrusion cavity and is evenly smeared on the inner wall of the outer plastic pipe blank, and then is extruded from the outer extrusion cavity to obtain an outer plastic pipe with an inner wall coated with rubber material. The outer plastic pipe then enters the channel and is coated on the outer wall of the composite steel pipe. By simplifying the production process and reducing the number of equipment used, the production cost of the composite pressure pipe is reduced.

[0035] 2. In the covering mold for the production of the PSP steel-plastic composite pressure pipe with a double-layer structure, a spiral groove is provided. After the plastic pipe raw material and rubber material are injected, they can be axially transported along the spiral grooves in the first compression chamber and the second compression chamber respectively until they enter the inner layer extrusion chamber, thereby improving the material transportation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the production flow chart of the existing steel-plastic composite pressure pipe;

[0037] Figure 2 This is a schematic diagram of the overall structure of the inner tube shaping member of the present invention;

[0038] Figure 3 Schematic diagram of the cross-sectional structure of the inner tube shaping member of the present invention;

[0039] Figure 4 This is a schematic diagram of the cross-sectional structure of the inner tube shaping member of the present invention;

[0040] Figure 5 for Figure 4 A schematic diagram of the structure at center A;

[0041] Figure 6 This is a schematic diagram of the overall structure of the outer tube shaping member of the present invention;

[0042] Figure 7 Schematic diagram of the cross-sectional structure of the outer tube shaping member of the present invention;

[0043] Figure 8 This is a schematic diagram of the cross-sectional structure of the outer tube shaping member of the present invention;

[0044] Figure 9 for Figure 8 Enlarged schematic diagram of the structure at point B in the middle.

[0045] The meaning of each number in the figure is:

[0046] 1. Inner tube feed channel; 2. Inner rubber feed channel; 3. Inner tube spiral; 4. Inner rubber spiral; 5. First core mold; 6. First spiral sleeve; 7. Compression flange; 8. First mold adjustment pressure ring; 9. Mold adjustment bolt; 10. Compression sleeve; 11. First die; 12. Outer tube feed channel; 13. Outer rubber feed channel; 14. Outer tube spiral; 15. Outer rubber spiral; 16. Second spiral sleeve; 17. Compression ring; 18. Second die; 19. Second core mold; 20. Second mold adjustment pressure ring. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0049] 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 the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0050] See also Figure 2-Figure 9 As shown, the purpose of this embodiment is to provide a coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure, including an inner pipe molding part and an outer pipe molding part;

[0051] The inner tube shaping part includes a double-layer feeding structure, a first inner mold assembly and a first outer mold assembly. The first inner mold assembly is located inside the first outer mold assembly, and the central axis of the first inner mold assembly coincides with the central axis of the first outer mold assembly. The outer wall of the first inner mold assembly cooperates with the inner wall of the first outer mold assembly to form an inner layer extrusion cavity.

[0052] One end of the double-layer feeding structure is connected to the inner layer extrusion cavity. The double-layer feeding structure is used to simultaneously inject the plastic tube raw material and the rubber material into the inner layer extrusion cavity, and then extrude them from the inner layer extrusion cavity to obtain the inner layer plastic tube with the outer wall coated with the rubber material;

[0053] The outer tube shaping part includes a hollow feed structure, a second inner mold assembly and a second outer mold assembly. The second inner mold assembly is located inside the second outer mold assembly, and the central axis of the second inner mold assembly coincides with the central axis of the second outer mold assembly. The outer wall of the second inner mold assembly cooperates with the inner wall of the second outer mold assembly to form an outer extrusion cavity.

[0054] The middle of the second inner mold assembly and the second outer membrane assembly are both provided with through openings, which are connected to the middle of the hollow feed structure to form a channel for the steel pipe to pass through, and one end of the outer layer extrusion cavity is connected to the channel;

[0055] The hollow feeding structure is connected to the other end of the outer extrusion cavity. The hollow feeding structure is used to inject the plastic tube raw material and the rubber into the outer extrusion cavity at the same time, and extrude them from the outer extrusion cavity to obtain an outer plastic tube with the inner wall coated with the rubber. The outer plastic tube is then covered on the outer wall of the steel tube by the outer extrusion cavity.

[0056] Compared with existing production processes (such as Figure 1 Unlike the above-mentioned method (shown as a method for producing a steel-plastic composite pressure pipe, which includes multiple independent steps such as extruding an inner plastic pipe, coating an inner rubber layer, welding a steel pipe, heating and curing, covering an outer plastic pipe, coating an outer rubber layer, and heating and curing), in the present invention, the steps of forming the inner plastic pipe and coating the outer wall of the inner plastic pipe with rubber are simultaneously performed by the inner pipe shaping member, and the steps of forming the outer plastic pipe and coating the inner wall of the outer plastic pipe with rubber are simultaneously performed by the outer pipe shaping member, thereby simplifying the production process of the steel-plastic composite pressure pipe. Specifically, the production process of the steel-plastic composite pressure pipe in the present invention is as follows:

[0057] The double-layer feeding structure simultaneously injects plastic tube raw material and rubber into the inner extrusion cavity. The plastic tube raw material flows along the outer wall of the first inner die assembly of the inner extrusion cavity, initially forming the inner plastic tube blank. The rubber flows along the inner wall of the first outer die assembly of the inner extrusion cavity and is evenly coated on the outer wall of the inner plastic tube blank. The inner plastic tube is then extruded from the inner extrusion cavity, resulting in an inner plastic tube with the outer wall coated with rubber.

[0058] The steel strip or steel plate is then rolled up and welded to obtain a steel pipe, which is then put on the inner plastic pipe and heated to solidify the rubber between the outer wall of the inner plastic pipe and the inner wall of the steel pipe, thereby obtaining a composite steel pipe with the inner plastic pipe bonded to the inner wall.

[0059] The composite steel pipe is inserted through the passage opening at one end of the hollow feed structure and moved to the other end of the passage. As the composite steel pipe moves along the passage, the hollow feed structure simultaneously injects plastic pipe raw material and rubber into the outer extrusion cavity. The plastic pipe raw material flows along the inner wall of the second outer die assembly of the outer extrusion cavity, initially forming an outer plastic pipe blank. The rubber then flows along the outer wall of the second inner die assembly of the outer extrusion cavity and is evenly applied to the inner wall of the outer plastic pipe blank. The rubber is then extruded from the outer extrusion cavity to form an outer plastic pipe with an inner wall coated with rubber. The outer plastic pipe then enters the passage and wraps around the outer wall of the composite steel pipe.

[0060] After the composite steel pipe passes through the other end of the channel, it is heated to solidify the rubber between the outer wall of the composite steel pipe and the inner wall of the outer plastic pipe, thereby obtaining a steel-plastic composite pressure pipe with plastic pipes bonded to the inner and outer layers. By simplifying the production process and reducing the number of equipment used, the production cost of the composite pressure pipe is reduced.

[0061] The above structure is disclosed below:

[0062] In order to be able to simultaneously inject plastic tube raw materials and rubber into the inner extrusion cavity, the double-layer feeding structure includes an inner tube feeding channel 1, an inner rubber feeding channel 2, an inner tube spiral 3, an inner rubber spiral 4 and a first spiral jacket 6. The inner tube spiral 3 is located in the middle of the first spiral jacket 6, and one end of the inner tube spiral 3 along the axial direction is fixedly connected to the inner wall of the first spiral jacket 6. The inner rubber spiral 4 is a hollow cylinder, and the inner rubber spiral 4 is installed between the outer wall of the inner tube spiral 3 and the inner wall of the first spiral jacket 6. The outer wall of the inner tube spiral 3 and the inner wall of the inner rubber spiral 4 cooperate to form a first compression chamber, and the outer wall of the inner rubber spiral 4 cooperates with the inner wall of the first spiral jacket 6 to form a second compression chamber. The first compression chamber and the second compression chamber are both connected to the inner layer extrusion chamber;

[0063] The inner tube feed channel 1 is fixedly embedded in one end of the first spiral outer sleeve 6. A first material channel is opened in the inner tube spiral body 3. The inner tube feed channel 1 is connected to the first material channel. The inner tube feed channel 1 is used to inject plastic tube raw materials. The plastic tube raw materials flow to the first compression chamber through the first material channel.

[0064] The inner rubber feed channel 2 is fixedly embedded in the side wall of the first spiral outer sleeve 6, and the inner rubber feed channel 2 is connected to the second compression chamber. The inner rubber feed channel 2 is used to inject rubber into the second compression chamber.

[0065] In the above-mentioned double-layer feeding structure, the plastic tube raw material and the rubber material are injected at the same time, that is, the plastic tube raw material is injected into the first material channel through the inner tube feeding channel 1, the plastic tube raw material enters the first compression chamber through the first material channel, and enters the inner layer extrusion chamber along the first compression chamber; the rubber material is directly injected into the second compression chamber through the inner rubber feeding channel 2, and then the rubber material enters the inner layer extrusion chamber along the second compression chamber.

[0066] In this embodiment, in order to improve the material conveying efficiency, spiral grooves are provided on the outer wall of the inner tube spiral 3 in the first compression chamber and the outer wall of the inner rubber spiral 4 in the second compression chamber. By providing the spiral grooves, after the plastic tube raw material and the rubber material are injected, they can be axially conveyed along the spiral grooves in the first compression chamber and the second compression chamber respectively until they enter the inner layer extrusion chamber, thereby improving the material conveying efficiency.

[0067] After the plastic tube raw material and rubber compound are injected into the inner layer extrusion cavity, they need to be extruded. The first inner mold assembly includes a first core mold 5 coaxially connected to the end of the inner tube spiral body 3 away from the inner tube feed channel 1. The first outer mold assembly includes a compression flange 7, a first mold adjustment ring 8, a compression sleeve 10 and a first die 11.

[0068] The compression flange 7 is fixedly connected to the end face of the first spiral sleeve 6 by bolts. The first die adjustment pressure ring 8 is sleeved on one end of the compression sleeve 10. The first die adjustment pressure ring 8 is fixedly connected to the compression flange 7 by bolts. The compression sleeve 10 is fixedly connected to the compression flange 7 through the first die adjustment pressure ring 8. The first die adjustment pressure ring 8 is provided with a die adjustment bolt 9 for fixing the compression sleeve 10. The first die 11 is fixedly connected to the other end of the compression sleeve 10 by bolts.

[0069] The outer wall of the first core mold 5 cooperates with the inner wall of the compression flange 7, the inner wall of the compression sleeve 10, and the inner wall of the first die 11 to form an inner extrusion cavity. The inner diameter of the compression flange 7 is larger than the inner diameter of the compression sleeve 10, and the inner diameter of the first die 11 is smaller than the inner diameter of the compression sleeve 10. In addition, the outer wall surface of the inner tube spiral 3 located in the compression flange 7 is inclined outward, and the inner wall surface of the compression flange 7 is narrowed inward at the corresponding position. The inner and outer walls of the inner rubber spiral 4 away from the end of the inner tube feed channel 1 are both inclined surfaces.

[0070] After the plastic tube raw material and the rubber are injected, they enter the inner extrusion cavity. First, the plastic tube raw material and the rubber enter the compression flange 7 end of the inner extrusion cavity along the first compression cavity and the second compression cavity respectively. Here, the plastic tube raw material flows out along the second material channel formed by the outer inclined surface of the outer wall of the inner tube spiral 3 and the inner wall inclined surface of the inner rubber spiral 4 to initially form an inner plastic tube blank, while the rubber flows out along the third material channel formed by the outer wall inclined surface of the inner rubber spiral 4 and the narrowing surface of the compression flange 7, contacts the outer wall of the inner plastic tube blank flowing out through the second material channel, and moves along the inner extrusion cavity at the same time. After the extrusion and compression treatment of the inner extrusion cavity, it is finally extruded from the end of the inner extrusion cavity to obtain an inner plastic tube with an outer wall evenly coated with rubber.

[0071] After the steel pipe is obtained by coiling and welding, it is put on the inner plastic pipe, and after heating and curing treatment, a composite steel pipe with an inner plastic pipe bonded to the inner wall is obtained. The composite steel pipe is then coated with an outer plastic pipe. The hollow feeding structure includes an outer tube feeding channel 12, an outer rubber feeding channel 13, an outer tube spiral 14, an outer rubber spiral 15 and a second spiral jacket 16. The outer tube spiral 14, the outer rubber spiral 15 and the second spiral jacket 16 are all hollow cylinders, and the central axes of the outer tube spiral 14, the outer rubber spiral 15 and the second spiral jacket 16 coincide with each other. The outer rubber spiral 15 is located on the inner side of the outer tube spiral 14, and the second spiral jacket 16 is located on the outer side of the outer tube spiral 14. The inner wall of the outer tube spiral 14 and the outer wall of the outer rubber spiral 15 cooperate to form a third compression chamber, and the outer wall of the outer tube spiral 14 and the inner wall of the second spiral jacket 16 cooperate to form a fourth compression chamber. The third compression chamber and the fourth compression chamber are both connected to the outer layer extrusion chamber.

[0072] The outer tube feed flow channel 12 is embedded in the side wall of the second spiral outer sleeve 16, and the outer tube feed flow channel 12 is connected to the fourth compression chamber. The outer tube feed flow channel 12 is used to inject plastic tube raw materials into the fourth compression chamber;

[0073] The outer rubber feed channel 13 is fixedly connected to the end surface of the second spiral sleeve 16 by bolts. The outer rubber feed channel 13 is communicated with the third compression chamber and is used to inject rubber into the third compression chamber.

[0074] Different from the above-mentioned double-layer feeding structure, in the hollow feeding structure, the third compression chamber for accommodating the rubber material is located on the inner side of the fourth compression chamber for accommodating the plastic tube raw material, so that when entering the outer layer extrusion chamber, the rubber material can be located on the inner side of the initially formed outer layer plastic tube blank, so that when flowing in the outer layer extrusion chamber, the rubber material can be evenly smeared on the inner wall of the outer layer plastic tube blank.

[0075] The second inner mold assembly includes a second die 18 fixedly connected to one end of the outer rubber spiral 15 away from the outer rubber feed channel 13, and the second outer mold assembly includes a compression ring 17, a second core mold 19 and a second mold adjustment pressure ring 20. The second die 18 and the second core mold 19 are both provided with through openings, and the through openings are connected to the middle of the outer rubber spiral 15 to form a channel for the steel pipe to pass through. One end of the compression ring 17 is fixedly connected to the end face of the second spiral sleeve 16 by a bolt, and the second mold adjustment pressure ring 20 is snap-fitted with one end of the second core mold 19. The second mold adjustment pressure ring 20 is fixedly connected to the other end of the compression ring 17 by a bolt;

[0076] The outer wall of the second die 18 cooperates with a portion of the inner wall of the second core die 19 to form an outer extrusion cavity, and the outlet of the outer extrusion cavity is connected to the channel;

[0077] An outer wall of the outer tube spiral body 14 at one end away from the outer rubber feed channel 13 is provided with an inclined surface, and the inner wall of the compression ring 17 is narrowed inwardly at a corresponding position.

[0078] In the process of passing the above-mentioned composite steel pipe through the channel, the plastic pipe raw material in the fourth compression chamber passes through the fourth material channel formed by the inclined surface of the outer tube spiral 14 and the narrowing surface of the compression ring 17, and enters the fifth material channel formed by the outer wall surface of the outer rubber spiral 15 and the inner wall surface of the compression ring 17, and initially forms the outer layer plastic pipe blank. The rubber flows along the third compression chamber to the fifth material channel, contacts the inner wall of the outer layer plastic pipe blank flowing out through the fourth material channel, and then passes through the inlet of the outer layer extrusion chamber at the same time and moves along the outer layer extrusion chamber. After the extrusion and compression treatment of the outer layer extrusion chamber, it is finally extruded from the outlet of the outer layer extrusion chamber to obtain an outer layer plastic pipe with an inner wall uniformly coated with rubber. The outer layer plastic pipe then enters the channel and is coated on the outer wall of the composite steel pipe. After subsequent processing, a steel-plastic composite pressure pipe can be obtained.

[0079] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure, comprising an inner pipe molding part and an outer pipe molding part, characterized in that: The inner tube shaping part includes a double-layer feeding structure, a first inner mold assembly and a first outer mold assembly, wherein the first inner mold assembly is located inside the first outer mold assembly, and the central axis of the first inner mold assembly coincides with the central axis of the first outer mold assembly, and the outer wall of the first inner mold assembly cooperates with the inner wall of the first outer mold assembly to form an inner layer extrusion cavity; One end of the double-layer feeding structure is connected to the inner layer extrusion cavity. The double-layer feeding structure is used to simultaneously inject the plastic tube raw material and the rubber material into the inner layer extrusion cavity, and then extrude them from the inner layer extrusion cavity to obtain an inner layer plastic tube with the outer wall coated with the rubber material; The outer tube shaping member includes a hollow feed structure, a second inner mold assembly and a second outer mold assembly, wherein the second inner mold assembly is located within the second outer mold assembly, and the central axis of the second inner mold assembly coincides with the central axis of the second outer mold assembly, and the outer wall of the second inner mold assembly cooperates with the inner wall of the second outer mold assembly to form an outer extrusion cavity; The middle of the second inner mold assembly and the second outer membrane assembly are both provided with a through opening, which is connected to the middle of the hollow feed structure to form a channel for the steel pipe to pass through, and one end of the outer layer extrusion cavity is connected to the channel; The hollow feeding structure is connected to the other end of the outer layer extrusion cavity. The hollow feeding structure is used to inject the plastic tube raw material and the rubber into the outer layer extrusion cavity at the same time, and extrude them from the outer layer extrusion cavity to obtain an outer layer plastic tube with the inner wall coated with rubber. The outer layer extrusion cavity then covers the outer layer plastic tube on the outer wall of the steel tube.

2. The coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure according to claim 1, characterized in that: The double-layer feeding structure comprises an inner tube feeding channel (1), an inner rubber feeding channel (2), an inner tube spiral (3), an inner rubber spiral (4) and a first spiral outer sleeve (6), wherein the inner tube spiral (3) is located in the middle of the first spiral outer sleeve (6), and one end of the inner tube spiral (3) is fixedly connected to the inner wall of the first spiral outer sleeve (6) along the axial direction, and the inner rubber spiral (4) is a hollow cylinder, and the inner rubber spiral (4) is installed between the outer wall of the inner tube spiral (3) and the inner wall of the first spiral outer sleeve (6), the outer wall of the inner tube spiral (3) and the inner wall of the inner rubber spiral (4) cooperate to form a first compression chamber, and the outer wall of the inner rubber spiral (4) and the inner wall of the first spiral outer sleeve (6) cooperate to form a second compression chamber, and the first compression chamber and the second compression chamber are both connected to the inner layer extrusion chamber; The inner tube feed channel (1) is fixedly embedded in one end of the first spiral outer sleeve (6), and a first material channel is opened in the inner tube spiral body (3). The inner tube feed channel (1) is connected to the first material channel. The inner tube feed channel (1) is used to inject plastic tube raw materials, and the plastic tube raw materials flow to the first compression chamber through the first material channel; The inner rubber feed channel (2) is fixedly embedded in the side wall of the first spiral outer sleeve (6), and the inner rubber feed channel (2) is connected to the second compression chamber. The inner rubber feed channel (2) is used to inject rubber into the second compression chamber.

3. The coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure according to claim 2, characterized in that: The outer wall of the inner tube spiral body (3) in the first compression chamber and the outer wall of the inner rubber spiral body (4) in the second compression chamber are both provided with spiral grooves.

4. The coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure according to claim 2, characterized in that: The first inner mold assembly comprises a first core mold (5) coaxially connected to one end of the inner tube spiral body (3) away from the inner tube feed channel (1); the first outer mold assembly comprises a compression flange (7), a first mold adjustment ring (8), a compression sleeve (10) and a first die (11); The compression flange (7) is fixedly connected to the end face of the first spiral sleeve (6); the first mold adjustment pressure ring (8) is sleeved on one end of the compression sleeve (10); the first mold adjustment pressure ring (8) is fixedly connected to the compression flange (7); the compression sleeve (10) is fixedly connected to the compression flange (7) via the first mold adjustment pressure ring (8); the first mold adjustment pressure ring (8) is provided with a mold adjustment bolt (9) for fixing the compression sleeve (10); and the first die (11) is fixedly connected to the other end of the compression sleeve (10); The outer wall of the first core die (5) cooperates with the inner wall of the compression flange (7), the inner wall of the compression sleeve (10), and the inner wall of the first die (11) to form the inner layer extrusion cavity. The inner diameter of the compression flange (7) is larger than the inner diameter of the compression sleeve (10), and the inner diameter of the first die (11) is smaller than the inner diameter of the compression sleeve (10).

5. The coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure according to claim 4, characterized in that: The outer wall of the inner tube spiral (3) located inside the compression flange (7) is inclined outward, and the inner wall of the compression flange (7) is narrowed inward at a corresponding position. The inner and outer walls of the inner rubber spiral (4) away from the end of the inner tube feed channel (1) are both inclined surfaces.

6. The coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure according to claim 1, characterized in that: The hollow feeding structure comprises an outer tube feeding channel (12), an outer rubber feeding channel (13), an outer tube spiral (14), an outer rubber spiral (15) and a second spiral outer sleeve (16); the outer tube spiral (14), the outer rubber spiral (15) and the second spiral outer sleeve (16) are all hollow cylinders, and the central axes of the outer tube spiral (14), the outer rubber spiral (15) and the second spiral outer sleeve (16) coincide with each other; the outer rubber spiral (15) is located on the inner side of the outer tube spiral (14); the second spiral outer sleeve (16) is located on the outer side of the outer tube spiral (14); the inner wall of the outer tube spiral (14) cooperates with the outer wall of the outer rubber spiral (15) to form a third compression chamber; the outer wall of the outer tube spiral (14) cooperates with the inner wall of the second spiral outer sleeve (16) to form a fourth compression chamber; the third compression chamber and the fourth compression chamber are both connected to the outer layer extrusion chamber; The outer tube feed channel (12) is embedded in the side wall of the second spiral outer sleeve (16), the outer tube feed channel (12) is connected to the fourth compression chamber, and the outer tube feed channel (12) is used to inject plastic tube raw materials into the fourth compression chamber; The outer rubber feed channel (13) is fixedly connected to the end surface of the second spiral sleeve (16), and the outer rubber feed channel (13) is communicated with the third compression chamber. The outer rubber feed channel (13) is used to inject rubber into the third compression chamber.

7. The coating mold for producing a PSP steel-plastic composite pressure pipe with a double-layer structure according to claim 6, characterized in that: The second inner mold assembly includes a second die (18) fixedly connected to one end of the outer rubber spiral (15) away from the outer rubber feed channel (13), the second outer mold assembly includes a compression ring (17), a second core mold (19) and a second mold adjustment pressure ring (20), the second die (18) and the second core mold (19) are both provided with the through opening, and the through opening is connected to the middle of the outer rubber spiral (15) to form the passage for the steel pipe to pass through, one end of the compression ring (17) is fixedly connected to the end face of the second spiral sleeve (16), the second mold adjustment pressure ring (20) is snap-fitted with one end of the second core mold (19), and the second mold adjustment pressure ring (20) is fixedly connected to the other end of the compression ring (17); The outer wall of the second die (18) cooperates with a portion of the inner wall of the second core die (19) to form the outer layer extrusion cavity, and the outlet of the outer layer extrusion cavity is connected to the channel; An outer wall of the outer tube spiral (14) at one end away from the outer rubber feed channel (13) is provided with an inclined surface, and a corresponding position of the inner wall of the compression ring (17) is narrowed inwardly.

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