Extruder die head structure for manufacturing axial hollow wall polyethylene pipe

Abstract

The utility model provides an extruder die head structure for manufacturing an axial hollow wall polyethylene pipe, and belongs to the technical field of dies. The problem of how to improve the production efficiency and ensure the yield at the same time is solved. The extruder die head structure for manufacturing the axial hollow wall polyethylene pipe comprises a tubular mouth die and a core rod arranged in the mouth die in a penetrating mode, an annular cavity is formed between the core rod and the mouth die, and a plurality of strip-shaped grooves communicated with the cavity are formed in the inner wall of the mouth die in the axial direction. The strip-shaped grooves are communicated with the feeding end and the discharging end of the mouth mold, and the multiple strip-shaped grooves are formed in the circumferential direction of the inner wall of the mouth mold at intervals. According to the extruder die head structure for manufacturing the axial hollow-wall polyethylene pipe, the yield can be ensured while the production efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of molds and relates to an extrusion die head structure for manufacturing axially hollow-walled polyethylene pipes. Background Technique

[0002] Polyethylene pipes, namely PE pipes, are very common pipes in current life, especially in the fields of water supply pipes and gas pipes. Nowadays, with the continuous development of technology, the types of polyethylene pipes are becoming more and more diverse. Among them, the polyethylene pipe with axially hollow walls is one of them. Briefly speaking, its specific structure includes an inner layer and an outer layer. In addition, it also includes a plurality of reinforcing ribs arranged axially between the inner layer and the outer layer.

[0003] In the prior art, for the manufacture of such polyethylene pipes, an extrusion die with a grid structure is used. The plastic melt is shunted, extruded, and bonded in the extrusion die to form the inner layer, reinforcing ribs, and outer layer of the pipe. After the pipe blank is extruded, it is cooled and formed by vacuum. The inner layer, outer layer, and reinforcing ribs are integrally formed, having the advantage of firm bonding of the structural walls.

[0004] However, from the actual production, due to the material characteristic that the polyethylene material itself has a slow cooling and shaping rate, and the structural particularity of the axially hollow-walled polyethylene pipe itself, the production efficiency of small-diameter axially hollow-walled polyolefin pipes with a diameter of less than 200 mm produced by the prior art is relatively low. For large-diameter pipes with a diameter of more than 200 mm, due to the large shrinkage rate of the polyethylene material and the structural particularity of the axially hollow-walled polyethylene pipe itself, the cooling rates of the inner layer, outer layer, and reinforcing ribs are different, and there will also be problems such as easy twisting and deformation of the reinforcing ribs and serious axial shrinkage marks on the inner wall, which cannot guarantee the product quality. Summary of the Invention

[0005] The purpose of the utility model is to address the above problems in the existing technology and propose an extrusion die head structure for manufacturing axially hollow-walled polyethylene pipes. The technical problem to be solved by the utility model is: how to ensure the finished product rate while improving the production efficiency.

[0006] The purpose of the utility model can be achieved by the following technical solutions: an extrusion die head structure for manufacturing axially hollow-walled polyethylene pipes, including a tubular die head and a mandrel inserted into the die head. An annular cavity is formed between the mandrel and the die head. The characteristic is that there are a plurality of strip-shaped grooves communicating with the cavity along the axial direction on the inner wall of the die head. Each of the strip-shaped grooves is arranged to communicate the feed end and the discharge end of the die head, and the plurality of strip-shaped grooves are arranged at intervals along the circumferential direction of the inner wall of the die head.

[0007] The working principle of the extrusion die head structure for manufacturing axially hollow-walled polyethylene pipes is as follows: The raw material is input through the feeding end of the die and output from the discharging end of the die. During this process, due to the presence of the mandrel in the die, the molten raw material is preliminarily shaped into a pipe blank in the cavity formed between the two during the flow process. On this basis, in this application, a number of strip-shaped grooves are provided on the inner wall of the die. These strip-shaped grooves are not only arranged along the axial direction of the die, but also arranged at intervals along the circumferential direction of the die. In addition, each strip-shaped groove also communicates with the feeding end and the discharging end of the die. That is to say, due to the existence of each strip-shaped groove, while extruding through the die and the mandrel to form a pipe blank (the formed pipe blank is regarded as the inner layer), due to the existence of the strip-shaped groove, a number of circumferentially spaced reinforcing ribs are directly formed on the outer peripheral wall of the pipe blank. It is worth mentioning that this application manufactures axially hollow-walled polyethylene pipes by a two-step method. Briefly speaking, it includes the first step: extruding and forming an inner layer with axially reinforcing ribs, and the second step: coating the outer wall of the inner layer to form an outer layer. This application mainly focuses on the production and processing of the inner layer with axially reinforcing ribs in the first step. Compared with the prior art, it can avoid the slow cooling caused by the structural reasons of this type of pipe, ensure the production efficiency. Secondly, for pipes with a diameter greater than 200 mm, it can ensure that the cooling rates of the inner layer and the reinforcing ribs tend to be consistent, effectively preventing problems such as the twisting and deformation of the reinforcing ribs and the shrinkage marks on the inner wall caused by the shrinkage and cooling of the material, and ensuring the yield rate of the pipes.

[0008] In the above extrusion die head structure for manufacturing axially hollow-walled polyethylene pipes, a number of ribs are axially arranged on the inner wall of the die. The aforenamed ribs are circumferentially spaced on the inner wall of the die, and a strip-shaped groove is formed between every two adjacent ribs. Through the arrangement of a number of ribs, a strip-shaped groove is formed between every two ribs in the die, which can avoid affecting the wall thickness of the die and ensure the structural strength of the die itself while ensuring the formation of the strip-shaped groove structure.

[0009] In the above extrusion die head structure for manufacturing axially hollow-walled polyethylene pipes, the cross-sectional profile of the aforenamed ribs along the radial section of the die is rectangular. Thus, the cross-section of the strip-shaped groove formed between every two ribs is also rectangular. On this basis, it can also ensure that the outer end face of the reinforcing rib integrally formed with the pipe blank is flat, ensuring sufficient contact area when extruding and coating to form the outer layer, and further ensuring higher structural strength of the produced axially hollow-walled polyethylene pipe.

[0010] In the above-mentioned extruder die head structure for manufacturing axially hollow-wall polyethylene pipes, the feeding end of the die has a flared material guiding part along the circumferential direction, and one end of the strip-shaped groove communicating with the feeding end of the die penetrates through the material guiding part. This enables the raw material to be depressurized before entering the cavity, ensuring that part of the raw material can smoothly enter the cavity and another part can smoothly enter each strip-shaped groove, guaranteeing that the quality of the formed pipe blank meets the standards.

[0011] In the above-mentioned extruder die head structure for manufacturing axially hollow-wall polyethylene pipes, each of the ribs includes a guiding section formed on the surface of the material guiding part, and each of the guiding sections is inclined outward along the radial direction of the die. The guiding section can guide the raw material entering the cavity, and at the same time, because it is inclined outward along the radial direction of the die, it can also achieve the effect of depressurization before the raw material enters the cavity, thereby ensuring the quality of the pipe blank formed by injection molding.

[0012] Compared with the prior art, the extruder die head structure for manufacturing axially hollow-wall polyethylene pipes of the present invention has the following advantages:

[0013] By circumferentially arranging a number of strip-shaped grooves in the die that communicate the feeding end and the discharging end of the die, a number of reinforcing ribs can be formed outside the pipe blank while extruding and forming the pipe blank. After forming the inner layer with reinforcing ribs, an outer layer is formed outside the several reinforcing ribs of the inner layer by means of extrusion coating, avoiding slow cooling and setting while preventing problems such as distortion of the reinforcing ribs and shrinkage marks on the inner wall caused by inconsistent shrinkage and cooling rates of the material, and ensuring the finished product rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram of the extruder die head structure for manufacturing axially hollow-wall polyethylene pipes of the present invention.

[0015] Figure 2 is a front view of the extruder die head structure for manufacturing axially hollow-wall polyethylene pipes of the present invention.

[0016] Figure 3 is Figure 2 a cross-sectional view taken along the direction of A - A.

[0017] Figure 4 is Figure 3 a partial enlarged view of A in

[0018] In the figure, 1, die; 11, strip-shaped groove; 12, rib; 121, guiding section; 122, forming section; 13, material guiding part; 2, mandrel; 3, cavity. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0020] like Figures 1-3 As shown, the die head structure of the extruder for manufacturing a circumferential hollow wall polyethylene pipe comprises a tubular die 1 and a core rod 2 inserted into the die 1, and an annular cavity 3 is formed between the outer circumferential wall of the core rod 2 and the inner circumferential wall of the die 1, one end of the die 1 is a feed end connected to the inlet of the cavity 3, and the other end is a discharge end connected to the outlet of the cavity 3, Figure 4 The inner wall of the die 1 is provided with a plurality of long strip-shaped ribs 12 along the circumferential direction, and each rib 12 is arranged along the axial direction of the die 1, so that a strip groove 11 arranged along the axial direction of the die 1 is formed between every two adjacent ribs 12, and the two ends of each strip groove are arranged through the feed end and the discharge end of the die, and the cross-sectional profile of each rib 12 cut along the radial direction of the die 1 is rectangular. The feed end of the die 1 is provided with a flared guide portion 13 along the circumferential direction, and each rib 12 includes a guide section 121 and a molding section 122 along the length direction, wherein the guide section 121 is molded on the guide section 13 of the die 1 and is arranged to be inclined outward along the radial direction of the die 1.

[0021] Working principle: The plastic melt is input into the cavity 3 from the feed end of the die 1 and output from the discharge end of the die 1. During the raw material input process, due to the flared shape of the feed end of the die 1 and the existence of the guide section 121 of each rib 12, the molten raw material is fully buffered and depressurized, and enters the cavity 3 in a relatively gentle state for shaping. In this process, due to the existence of each strip groove 11, a plurality of reinforcing ribs are extruded and integrally formed on the outer circumferential wall of the tube blank while forming the tube blank. Compared with the prior art, the present application can quickly prepare an inner layer with a plurality of reinforcing ribs on the outer wall through this means, which is beneficial to the cooling and shaping of the reinforcing ribs and the inner layer of the pipe. Subsequently, it is only necessary to extrude and coat the outer layer of the plurality of reinforcing ribs so that the outer layer and the reinforcing ribs are hot-melted into one.

[0022] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0023] Although the terms such as die 1, strip groove 11, rib 12, guide section 121, forming section 122, core rod 2, and cavity 3 are frequently used in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the utility model; interpreting them as any additional restrictions is contrary to the spirit of the utility model.

Claims

1. An extrusion die head structure for manufacturing an axially hollow-wall polyethylene pipe, comprising a tubular die orifice (1) and a mandrel (2) inserted into the die orifice (1). An annular cavity (3) is formed between the mandrel (2) and the die orifice (1), characterized in that, On the inner wall of the die (1), there are a number of strip-shaped grooves (11) axially communicating with the cavity (3). Each of the strip-shaped grooves (11) is arranged to communicate the feed end and the discharge end of the die (1), and the number of the strip-shaped grooves (11) is arranged at intervals along the circumferential direction of the inner wall of the die (1).

2. The extruder die structure for manufacturing an axially hollow-wall polyethylene pipe according to claim 1, characterized in that, On the inner wall of the die (1), there are a number of ribs (12) axially. The number of the ribs (12) is arranged at intervals along the circumferential direction of the inner wall of the die (1), and the strip-shaped groove (11) is formed between every two adjacent ribs (12).

3. The die head structure of the extruder for manufacturing axially hollow-wall polyethylene pipes according to claim 2, characterized in that, The cross-sectional profile of the number of the ribs (12) cut along the radial direction of the die (1) is rectangular.

4. The extruder die structure for manufacturing an axially hollow-wall polyethylene pipe according to claim 2 or 3, characterized in that, The feed end of the die (1) has a flared material guiding part (13) along the circumferential direction. One end of the strip-shaped groove (11) communicating with the feed end of the die (1) penetrates through the material guiding part (13).

5. The extruder die structure for manufacturing an axially hollow-wall polyethylene pipe according to claim 4, characterized in that, Each of the ribs (12) includes a guiding section (121) formed on the surface of the material guiding part (13), and each of the guiding sections (121) is inclined outward along the radial direction of the die (1).

Images