Composite pipe PVC outer plastic feeding die

Abstract

The application relates to the technical field of PVC composite pipe production equipment, and particularly discloses a PVC outer plastic feeding die head for composite pipes, which comprises a composite die head and an extrusion die head fixedly connected, an internal core is arranged in the extrusion die head, a rotating core is arranged in the composite die head, an inner cavity opening to the direction of the extrusion die head is arranged on the rotating core, an outer flow channel is formed between the rotating core and the composite die head, one end of the internal core is inserted into the inner cavity of the rotating core to form an inner flow channel, a composite flow channel, a containing flow channel and an extrusion flow channel are sequentially formed between the internal core and the extrusion die head, the width of the containing flow channel connected with one end of the composite flow channel is consistent with the width of the composite flow channel, the width of the containing flow channel connected with one end of the extrusion flow channel is consistent with the width of the extrusion flow channel, and the width of the containing flow channel in the middle is greater than the widths of the composite flow channel and the extrusion flow channel. The technical problem of the risk that PVC material in the die head is prone to blockage and coking in the flow channel after being compounded in the prior art is solved.

Description

Technical Field

[0001] This utility model relates to the technical field of PVC composite pipe production equipment, specifically a PVC outer plastic feeding die for composite pipes. Background Technology

[0002] Currently, co-extrusion technology for polymer plastic composite pipes has matured. The typical process involves adding an inner sleeve to the inner layer of a single-layer extrusion die, dividing the die into inner and outer flow channels. The inner flow channel connects upstream to the main extruder, while the outer flow channel opens on the outside of the die and connects to the auxiliary extruder, thus achieving co-extrusion molding of a double-layer composite pipe. To produce multi-layer composite pipes, a corresponding number of inner sleeves can be added to the die to divide the flow channels into multiple layers, each connected to a corresponding auxiliary extruder to complete the composite process.

[0003] However, this technology has a significant bottleneck: polymer plastics already experience high internal resistance in the extrusion die. Adding an inner sleeve to form a composite flow path further exacerbates the die resistance, obstructing material flow and leading to a sudden increase in pressure within the die. Traditional composite extrusion dies can barely produce double-layer composite pipes; the increased resistance from the additional inner sleeves and the resulting die overload not only make production extremely difficult and inefficient but also severely shorten the die's lifespan. This problem is particularly pronounced in PVC composites: PVC, as a heat-sensitive material, has poor thermal stability and flowability. Material is prone to localized stagnation or flow stoppage within the flow channels. Under long-term production, material coking in stagnant areas easily leads to excessively high die pressure, ultimately causing die cracking or even complete failure, severely restricting the industrial application of PVC multilayer composite pipes.

[0004] To address the aforementioned issues of high PVC flow resistance, material coking, increased mold pressure, and even mold cracking, existing technologies primarily focus on improving the die head's piping design. This optimization enhances flowability. For instance, patent CN217670966U discloses a PVC multi-layer composite mold with an extrusion die and a composite die. Both the extrusion and composite dies have interconnected extrusion and feeding chambers. The extrusion chamber contains an extrusion channel, while the feeding chamber contains a first and a second channel. This optimized channel design maintains pressure stability and smooth flow during extrusion, enabling the production of PVC multi-layer composite pipes.

[0005] While the above methods can improve material flow and stabilize mold pressure to some extent, when the outer and inner PVC materials of the mold head are combined into a double-layer structure, a certain composite pressure is generated in the composite flow channel in order to allow the two layers to penetrate each other and form a good bonding surface. This can lead to material blockage in the composite flow channel, material accumulation and temperature rise in the pipeline, and there is a risk of flow channel blockage and coking after the PVC double-layer pipe is composited. Utility Model Content

[0006] The purpose of this utility model is to provide a composite pipe PVC outer plastic feeding die head to solve the technical problem mentioned above. When the outer and inner PVC materials of the existing die head are combined into a double-layer structure, in order to make the two layers of materials penetrate each other during the bonding process and form a good bonding surface, a certain composite pressure will be formed in the composite flow channel. This will cause the material to be easily blocked in the flow channel after bonding, and the material will accumulate and heat up in the pipeline. There is a risk of flow channel blockage and coking after the PVC double-layer pipe is bonded.

[0007] To solve the above problems, the technical solution adopted by this utility model is as follows: A composite pipe PVC outer plastic feeding die head includes a composite die head and an extrusion die head, which are fixedly connected as a whole. The extrusion die head is provided with an internal core, and the composite die head is provided with a rotating core. The rotating core is provided with an inner cavity that opens towards the extrusion die head. An outer flow channel is formed between the rotating core and the composite die head. One end of the internal core is inserted into the inner cavity of the rotating core to form an inner flow channel. Along the PVC material flow direction, a composite flow channel, a receiving flow channel, and an extrusion flow channel are sequentially connected between the internal core and the extrusion die head. The width of the receiving flow channel at the end connected to the composite flow channel is the same as that of the composite flow channel, and the width at the end connected to the extrusion flow channel is the same as that of the extrusion flow channel. However, the width in the middle of the receiving flow channel is greater than the width of the composite flow channel and the extrusion flow channel.

[0008] The beneficial effects of this implementation plan are as follows: In existing technologies, when the outer and inner PVC materials of the die head are laminated into a double-layer structure, a certain lamination pressure is generated in the lamination channel to allow the two layers to penetrate each other and form a good bonding surface. This leads to easy blockage of the material in the lamination channel, material accumulation and temperature rise in the pipeline, and there is a risk of channel blockage and coking after the PVC double-layer pipe is laminated. In contrast, this application sets up a receiving channel after the lamination channel. By using the sudden widening of the receiving channel, the PVC material after lamination is less likely to accumulate and heat up after lamination, thus preventing coking.

[0009] Furthermore, the extrusion die and the inner core of the receiving channel are provided with a composite temperature control component that can heat or cool the PVC double-layer material.

[0010] Furthermore, the composite temperature control component includes staggered cooling water pipes and heating rings.

[0011] Furthermore, the cooling water pipe has an 8-shaped structure, with an inlet pipe at one end and an outlet pipe at the other end.

[0012] Furthermore, the heating ring is a notched annular shape.

[0013] Furthermore, both the composite die head and the extrusion die head are provided with connecting ear plates, and the connecting ear plates are provided with threaded holes. The composite die head and the extrusion die head are fixedly connected by bolts passing through the threaded holes, and a clamp is also provided on the outside of the connecting ear plates. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model. Figure 2 This is a schematic diagram of the composite temperature control component of this utility model. Detailed Implementation

[0015] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: composite die head 1, inner layer feed port 11, outer layer feed port 12, connector head 13, extrusion die head 2, extrusion section 21, expansion section 22, connecting section 23, internal core 3, extrusion head 31, narrow waist 32, insertion end 33, rotating core 4, fixing part 41, outer layer flow channel 51, inner layer flow channel 52, composite flow channel 53, receiving flow channel 54, extrusion flow channel 55, composite temperature control component 6, cooling water pipe 61, water inlet pipe 611, water outlet pipe 612, heating ring 62, first wire 621, second wire 622, clamp 7.

[0016] Implementation, for example, attached Figure 1-2 As shown: A composite pipe PVC outer plastic feeding die head includes a composite die head 1 and an extrusion die head 2, wherein the composite die head 1 and the extrusion die head 2 are fixedly connected.

[0017] The extrusion die 2 includes an extrusion section 21, an expansion section 22, and a connecting section 23, such as... Figure 1As shown, the extrusion die 2 has an extrusion cavity with a spindle structure inside. An internal core 3, smaller than the extrusion cavity, is located within the extrusion cavity. The internal core 3 is fixedly connected to the inner wall of the extrusion cavity by a rod-shaped internal core fixing member 34. The internal core 3 includes three parts: an extrusion head 31, a narrow waist 32, and an insertion end 33, which correspond to the extrusion cavities at the extrusion section 21, expansion section 22, and connecting section 23 of the extrusion die 2, respectively. The extrusion head 31 has a cylindrical structure, and its gap width with the extrusion cavity of the extrusion section 21 is consistent, forming an extrusion flow channel 55. The narrow waist 32 extends to the right from the right side of the extruder head 31. During its extension, the diameter of the narrow waist 32 gradually decreases. After shrinking to the middle, it continues to extend to the right, but its diameter gradually increases until it connects with the insertion end 33. Therefore, the narrow waist 32 has a structure with a large diameter at both ends and a small diameter in the middle. The gap between the narrow waist 32 and the extrusion cavity of the expansion section 22 forms a receiving channel 54. Since the extrusion cavity has a spindle structure, the inner diameter of the middle cavity is the largest. Since the narrow waist has a structure with a large diameter at both ends and a small diameter in the middle, the resulting receiving channel 54 has a variable diameter structure with a small width at both ends and a large width in the middle. The narrow waist has an internal core fixing member 34 at the point where the diameter is smallest, which connects to the inner wall of the extrusion cavity. The insertion end 33, which extends to the right of the narrow waist 32, also has a cylindrical structure and is also provided with an internal core fixing member 34, which connects to the inner wall of the extrusion cavity of the extrusion die head. The rightmost side of the insertion end 33 is a chamfered arc surface, and the diameter of the insertion end 33 is smaller than that of the extrusion head 31. The gap between the insertion end 33 and the connecting section 23 forms a composite flow channel 53. The width of the composite flow channel 53 is greater than the width of the extrusion flow channel 55. In general, the extrusion cavity of the internal core 3 and the extrusion die 2 forms a composite flow channel 53, a receiving flow channel 54, and an extrusion flow channel 55 from left to right. The width changes as follows: the composite flow channel 53, which maintains a constant width, gradually transitions to the receiving flow channel 54, which has the largest width in the middle and the smallest width at both ends, and finally transitions to the extrusion flow channel 55 as the width of the receiving flow channel 54 gradually decreases.

[0018] The right end of the extrusion die 2 is connected to the composite die 1. The leftmost end of the composite die 1 is provided with a connector 13, and both the connector 13 and the rightmost end of the extrusion die 2 are provided with connecting ear plates. The connecting ear plates are provided with threaded holes (not shown in the figure). When connecting, the two are aligned, and the composite die 1 and the extrusion die 2 are connected as a whole through the threaded holes on the connecting ear plates. After the bolts and nuts are fixed, the outside of the connecting ear plates is reinforced with clamps 7.

[0019] The composite die head 1 has a composite cavity, which is connected to the inner layer inlet on the right side of the composite die head 1. A rotating core 4 is located within the composite cavity, and the rotating core 4 is coaxially fixed to the composite cavity using a rotating core fixing member 41. A gap exists between the rotating core 4 and the composite cavity, serving as an outer layer flow channel 51. The rotating core 4 also has a cavity structure, with an inner layer cavity opening towards the extrusion die head 2 in its middle. After the composite die head 1 and the extrusion die head 2 are fixed, the insertion end 33 of the inner core 3 inside the extrusion die head 2 is inserted into the inner layer cavity of the rotating core 4. The gap between the insertion end 33 and the inner layer cavity forms the inner layer flow channel 52. The inner layer cavity is connected to the inner layer inlet 11 via a pipe. The feeding directions of the inner layer inlet 11 and the outer layer inlet 12 intersect, with an angle less than 60°, which is 45° in this embodiment. Therefore, the inner feed inlet 11 is as follows Figure 1 As shown, it is tilted to the right on the composite die head 1, and both it and the outer feed port 12 feed from right to left.

[0020] In the die head of this application, a composite temperature control component 6 is provided at the middle part of the extrusion die head 2, that is, at the corresponding position of the narrow waist 32. The structure of the composite temperature control component 6 is as follows: Figure 2 As shown, the composite temperature control assembly is arranged around the receiving channel 54, including a figure-eight shaped cooling water pipe 61 and two O-shaped heating rings 62, which are arranged alternately. The cooling water pipes 61 are fed into the inlet pipe 611 at one end of the figure-eight shape, and after filling the three layers of cooling water pipes 61, water exits from the outlet pipe 612 at the other end of the figure-eight shape. Therefore, the water flow velocity in the cooling water pipes 61 can be used to cool the PVC material in the receiving channel 54. The heating rings 62 are resistance wires, with two notched annular electric heating rings 62 on each layer. The two electric heating rings are independent and not connected to each other, and the electric heating rings 62 on the left and right sides have the same structure. The electric heating rings 62 on different layers on the same side are connected in parallel with the first wire 621 and the second wire 622 through the notch. After the composite temperature control component 6 is laid in the extrusion die 2, its first and second wires, inlet pipe, and outlet pipe are led out, and an external power supply and water source are connected. The composite temperature control component 6 can control the temperature of the material in the flow channel 54, maintaining its fluidity while controlling its temperature to not exceed the coking temperature of PVC.

[0021] The above descriptions are merely embodiments of this utility model, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this utility model, and these should also be considered within the scope of protection of this utility model. These modifications will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A composite pipe PVC outer plastic feeding die, comprising a composite die and an extrusion die fixedly connected, characterized in that: The extrusion die head has an internal core, and the composite die head has a rotating core. The rotating core has an inner cavity that opens towards the extrusion die head. An outer flow channel is formed between the rotating core and the composite die head. One end of the internal core is inserted into the inner cavity of the rotating core to form an inner flow channel. Along the PVC material flow direction, a composite flow channel, a receiving flow channel, and an extrusion flow channel are sequentially connected between the internal core and the extrusion die head. The width of the receiving flow channel at the end connected to the composite flow channel is the same as that of the composite flow channel, and the width at the end connected to the extrusion flow channel is the same as that of the extrusion flow channel. However, the width in the middle of the receiving flow channel is greater than the width of the composite flow channel and the extrusion flow channel.

2. The composite pipe PVC outer plastic feeding die head according to claim 1, characterized in that: The extrusion die and the inner core of the receiving channel are equipped with a composite temperature control component that can heat or cool the PVC double-layer material.

3. The composite pipe PVC outer plastic feeding die head according to claim 2, characterized in that: The composite temperature control component includes staggered cooling water pipes and heating rings.

4. The composite pipe PVC outer plastic feeding die head according to claim 3, characterized in that: The cooling water pipe has an 8-shaped structure, with an inlet pipe at one end and an outlet pipe at the other end.

5. The composite pipe PVC outer plastic feeding die head according to claim 3, characterized in that: The heating ring is a notched annular shape.

6. The composite pipe PVC outer plastic feeding die head according to claim 1, characterized in that: Both the composite die head and the extrusion die head are provided with connecting ear plates, and the connecting ear plates are provided with threaded holes. The composite die head and the extrusion die head are fixedly connected by bolts passing through the threaded holes. A clamp is also provided on the outside of the connecting ear plate.

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