Sizing sleeve for manufacturing polyolefin pipe with axial hollow wall

Abstract

The utility model provides a sizing sleeve for manufacturing an axial hollow wall polyolefin pipe, and belongs to the technical field of molds. The problem of how to improve the production efficiency and yield of pipes is solved. The sizing sleeve for manufacturing the polyolefin pipe with the axial hollow wall comprises a body with a feeding end and a discharging end and a cooling water jacket fixed outside the feeding end of the body in the circumferential direction, a plurality of cooling water holes arranged at intervals are formed in the outer wall of the feeding end of the body in the circumferential direction, and a plurality of strip-shaped grooves are formed in the body in the length direction. The multiple strip-shaped grooves penetrate through the feeding end and the discharging end of the body, and the multiple strip-shaped grooves are formed in the circumferential direction of the inner wall of the body at intervals. The sizing sleeve for manufacturing the polyolefin pipe with the axial hollow wall can improve the production efficiency and the yield of the pipe.

Description

Technical Field

[0001] The utility model belongs to the technical field of molds and relates to a sizing sleeve for manufacturing an axially hollow-walled polyolefin pipe. Background Art

[0002] Polyethylene pipes are very common pipes in current life and are indispensable pipes in the current water supply and drainage as well as gas fields.

[0003] Nowadays, with the continuous development of technology, the types of polyethylene pipes are becoming more and more diverse. Among them, the polyethylene pipe with an axially hollow wall is one of them. Simply speaking, its specific structure includes an inner layer and an outer layer. In addition, it also includes a number of reinforcing ribs arranged axially between the inner layer and the outer layer.

[0004] 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, so that the inner layer, outer layer, and reinforcing ribs are formed into one body.

[0005] However, from the actual production, due to the material characteristics of slow cooling and setting of the polyethylene material itself, combined with the special structure 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 special structure 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

[0006] The purpose of the utility model is to propose a sizing sleeve for manufacturing an axially hollow-walled polyolefin pipe in view of the above problems existing in the prior art. The technical problem to be solved by the utility model is: how to improve the production efficiency and the finished product rate of the pipe.

[0007] The purpose of the utility model can be achieved by the following technical solutions: A sizing sleeve for manufacturing an axially hollow-walled polyolefin pipe includes a body having a feed end and a discharge end and a cooling water jacket fixedly arranged outside the feed end of the body along the circumferential direction. It is characterized in that a number of cooling water holes are arranged at intervals along the circumferential direction on the outer wall of the feed end of the body, and a number of strip-shaped grooves are arranged along the length direction in the body. A number of the strip-shaped grooves all penetrate through the feed end and the discharge end of the body, and a number of the strip-shaped grooves are arranged at intervals along the circumferential direction of the inner wall of the body.

[0008] The working principle of the sizing sleeve for manufacturing axially hollow-wall polyolefin pipes is as follows: When the raw materials are extruded through the die of the extruder, the molten raw materials are preliminarily shaped into a pipe blank, and at this time, several reinforcing ribs integrally formed by extrusion are provided on the outer wall of the formed pipe blank. After the pipe blank is extruded from the die, it can directly enter the cavity of the main body through the feeding end of the main body. Due to the existence of several strip-shaped grooves provided on the inner wall of the main body, after the cooled pipe blank enters through the feeding end of the main body, it is ensured that each reinforcing rib can be correspondingly embedded in each strip-shaped groove. The existence of each strip-shaped groove can not only prevent the pipe blank from rotating during the extrusion process, but also play a role in shaping and maintaining each reinforcing rib, preventing the deformation of the reinforcing ribs during the transition of the pipe blank from the die to the sizing sleeve. Under this premise, the extruder can input cooling water into the cooling water jacket through an external pipeline, and the cooling water jacket inputs cooling water into the inner cavity of the main body through the cooling water holes opened on the side wall of the main body, so as to quickly cool the pipe blank and each reinforcing rib at the same cooling rate through heat exchange until the pipe blank is extruded from the sizing sleeve. It is worth mentioning that the above-mentioned pipe blank with reinforcing ribs can be regarded as the inner layer in the prior art. This application manufactures axially hollow-wall 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 deformation of the reinforcing ribs and shrinkage marks on the inner wall caused by the shrinkage and cooling problems of the material, and ensuring the yield rate of the pipes.

[0009] In the above-mentioned sizing sleeve for manufacturing axially hollow-wall polyolefin pipes, several rib strips are arranged along the length direction in the main body, and several of the rib strips are arranged at intervals along the circumferential direction of the inner wall of the main body, and a strip-shaped groove is formed between every two adjacent rib strips. To ensure that several strip-shaped grooves are formed in the main body while avoiding the influence of the opening of the strip-shaped grooves on the wall thickness of the main body and ensuring the structural strength of the main body.

[0010] In the above-mentioned sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe, a part of the cooling water holes are in one-to-one correspondence with the positions of the respective strip-shaped grooves, and another part of the cooling water holes are in one-to-one correspondence with the positions of the respective ribs. An annular groove is circumferentially formed on the inner wall of the feed end of the body, and the annular groove communicates with each of the cooling water holes. This is to achieve a uniform circumferential distribution of a number of cooling water holes along the inner wall of the body, and to connect a number of cooling water holes in series through the annular groove, so that the cooling water introduced into the cooling water jacket from the outside enters the body through each cooling water hole, and after contacting the outer surface of the pipe blank along the annular groove for heat exchange, it is discharged to the outside, thereby ensuring the cooling and shaping effect on the pipe blank.

[0011] In the above-mentioned sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe, the cooling water holes are provided in several groups, and several groups of the cooling water holes are arranged at intervals along the length direction of the body. The annular grooves are provided in several numbers and are arranged at intervals along the length direction of the body, and several of the annular grooves are in one-to-one correspondence with several groups of the cooling water holes. Through the cooperation of several annular grooves and several groups of cooling water holes, the contact area between the cooling water and the pipe blank at the feed end of the body can be increased, and the cooling and shaping effect on the pipe blank can be further improved.

[0012] In the above-mentioned sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe, a number of long strip-shaped vacuum suction holes are formed on the body behind the cooling water jacket, and several of the vacuum suction holes are arranged at intervals along the circumference of the body. After the cooling and shaping of the pipe blank is completed, actually the pipe blank is not completely hardened and shaped at this time. Under the action of the extrusion pressure of the pipe blank, it passes through the cooling water jacket, and through the vacuum action generated in the body by each vacuum suction hole, the outer wall of the pipe blank is completely attached to the inner wall of the body, so as to ensure that the roundness of the pipe blank meets the requirements during the subsequent continuous cooling and shaping process.

[0013] In the above-mentioned sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe, the vacuum suction holes are provided in several groups, and several groups of the vacuum suction holes are arranged at intervals along the length direction of the body. On the basis of the above, the arrangement of several groups of vacuum suction holes is adopted to ensure that the vacuum suction effect on the body is more obvious, and further ensure the fitting state between the outer wall of the pipe blank and the inner wall of the body when the pipe blank passes through, so as to further improve the roundness of the extruded pipe.

[0014] In the above-mentioned sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe, every two adjacent groups of the vacuum suction holes are arranged in a circumferential dislocation along the body. Through this arrangement, it is ensured that during the passing process of the pipe blank, the generated vacuum action alternates circumferentially around the pipe blank, thereby preventing the situation of partial deformation of the pipe blank.

[0015] Compared with the prior art, the sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe of the present invention has the following advantages:

[0016] 1. Through the cooperation of cooling water holes and a number of strip grooves, it is realized that a number of reinforcing ribs on the outer wall of the extruded tube blank can be correspondingly embedded in each strip groove one by one. The groove walls of the strip grooves are used to shape and hold the reinforcing ribs, and then cooling water is introduced through the cooling water channels in cooperation with the cooling water holes. By means of heat exchange, the effect of quickly cooling and shaping the tube blank is achieved, and further the purpose of directly forming the reinforcing ribs outside the tube blank is achieved. In this way, while ensuring the structural strength, the processing steps are reduced, and the production efficiency of the pipe is guaranteed.

[0017] 2. Ensure that the cooling rates of the formed tube blank and each reinforcing rib tend to be consistent, prevent problems such as easy distortion and deformation of the reinforcing ribs and serious axial shrinkage marks on the inner wall. Subsequently, only the outer layer needs to be extruded and coated outside a number of reinforcing ribs to ensure the finished product rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural view of a sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe.

[0019] Figure 2 is a top view of a sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe.

[0020] Figure 3 is Figure 2 a cross-sectional view taken along the A-A direction and its partial enlarged view.

[0021] Figure 4 is Figure 2 a cross-sectional view taken along the B-B direction and its partial enlarged view.

[0022] In the figure, 1. Body; 11. Feed end; 12. Discharge end; 13. Cooling water hole; 14. Strip groove; 15. Rib; 16. Vacuum suction hole; 17. Annular groove; 2. Cooling water jacket. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following are specific embodiments of the present invention in combination with the drawings, and the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0024] As Figure 1 shown in Figure 2 the sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe includes a tubular body 1. One end of the body 1 is a feed end 11 for connecting to the die of an extruder, and the other end is a discharge end 12 for outputting the formed pipe. It should be noted that the pipe formed by this sizing sleeve in this application is equivalent to the inner layer in the prior art.

[0025] Combined with Figure 3 and Figure 4, a cooling water jacket 2 is fixedly mounted on the outer circumference of the feeding end 11 of the body 1 through bolts. A plurality of connectors for water inlet and outlet are arranged on the outer peripheral wall of the cooling water jacket 2, and a water-containing cavity is formed between the outer wall of the cooling water jacket 2 and the feeding end 11 of the body 1. A plurality of ribs 15 are integrally formed on the inner wall of the body 1 along the length direction. The plurality of ribs 15 are arranged at intervals along the inner circumference of the body 1, and a strip-shaped groove 14 in the shape of a long strip is formed between every two adjacent ribs 15 in cooperation with the inner wall of the body 1. A plurality of groups of cooling water holes 13 penetrating through the inner wall of the body 1 are formed in the outer wall of the body 1 near the feeding end 11. The plurality of groups of cooling water holes 13 are arranged at intervals along the length direction of the body 1. Each group of cooling water holes 13 has a plurality of holes and is arranged at intervals along the circumference of the body 1. Among them, some of the cooling water holes 13 in the same group penetrate through the bottom wall of each strip-shaped groove 14 in one-to-one correspondence, and the other part of the cooling water holes 13 penetrate through the outer wall of each rib 15 in one-to-one correspondence. Moreover, a plurality of annular grooves 17 are formed on the inner wall of the body 1 near the feeding end 11 along the circumference. The annular grooves 17 and each group of cooling water holes 13 are in one-to-one correspondence in terms of displacement. That is to say, a plurality of cooling water holes 13 in the same group are connected through an annular groove 17.

[0026] A plurality of groups of strip-shaped vacuum suction holes 16 are formed on the outer wall of the body 1 behind the cooling water jacket 2 along the length direction. The plurality of groups of vacuum suction holes 16 are arranged at intervals along the length direction of the body 1. Each group of vacuum suction holes 16 has a plurality of holes and is arranged at intervals along the circumference of the body 1. In addition, it is worth mentioning that any two adjacent groups of vacuum suction holes 16 are arranged in a circumferential dislocation manner along the body 1.

[0027] Working principle: The pipe blank extruded and formed through the die enters from the feeding end 11 of the body 1, and a plurality of reinforcing ribs formed on the outer surface of the pipe blank are embedded in the strip-shaped grooves 14 formed in the body 1 in one-to-one correspondence. At the same time, cooling water is introduced into the cooling water jacket 2 through an external pipeline and then introduced into the body 1 through each group of cooling water holes 13. The cooling water entering through each group of cooling water holes 13 flows around the circumference of the pipe blank in each annular groove 17, so as to achieve the effect of heat exchange and realize the rapid cooling of the pipe blank. After the pipe blank passes through the cooling water jacket 2, the vacuum pumping device in the extruder sucks outwards through each group of vacuum suction holes 16, so that the outer circumferential wall of the pipe blank fits against the inner wall of the body 1 under the cooperation of each group of vacuum suction holes 16, thereby ensuring the roundness of the formed pipe blank. And with the subsequent extrusion force, the cooled and shaped pipe blank is pushed out of the discharging end 12 of the body 1.

[0028] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0029] Although terms such as body 1, feed end 11, discharge end 12, cooling water holes 13, strip grooves 14, ribs 15, vacuum suction holes 16, annular grooves 17, and cooling water jacket 2 are used more frequently in this article, the possibility of using other terms is not excluded. The use of these terms is only for more convenient description and explanation of the essence of the present utility model; interpreting them as any additional limitation is contrary to the spirit of the present utility model.

Claims

1. A sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe, comprising a body (1) having a feed end (11) and a discharge end (12), and a cooling water jacket (2) circumferentially fixed outside the feed end (11) of the body (1), characterized in that, On the outer wall of the feeding end (11) of the body (1), a plurality of cooling water holes (13) are circumferentially formed at intervals. Inside the body (1), there are a plurality of strip-shaped grooves (14) along the length direction. The plurality of strip-shaped grooves (14) all penetrate through the feeding end (11) and the discharging end (12) of the body (1), and the plurality of strip-shaped grooves (14) are circumferentially spaced along the inner wall of the body (1).

2. The sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe according to claim 1, characterized in that, Inside the body (1), there are a plurality of rib strips (15) arranged along the length direction. The plurality of rib strips (15) are circumferentially spaced along the inner wall of the body (1), and a strip-shaped groove (14) is formed between every two adjacent rib strips (15).

3. The sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe according to claim 2, characterized in that, A part of the cooling water holes (13) are in one-to-one correspondence with the positions of the strip-shaped grooves (14), and another part of the cooling water holes (13) are in one-to-one correspondence with the positions of the rib strips (15). On the inner wall of the feeding end (11) of the body (1), a circular groove (17) is circumferentially formed, and the circular groove (17) is communicated with each of the cooling water holes (13).

4. The sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe according to claim 3, characterized in that, The cooling water holes (13) have several groups, and the several groups of cooling water holes (13) are spaced along the length direction of the body (1). The circular grooves (17) have several and are spaced along the length direction of the body (1), and the several circular grooves (17) are in one-to-one correspondence with the several groups of cooling water holes (13).

5. The sizing sleeve for manufacturing an axially hollow-walled polyolefin pipe according to claim 4, characterized in that, On the body (1) behind the cooling water jacket (2), several long strip-shaped vacuum suction holes (16) are formed, and the several vacuum suction holes (16) are circumferentially spaced along the body (1).

6. The sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe according to claim 5, characterized in that, The vacuum suction holes (16) have several groups, and the several groups of vacuum suction holes (16) are spaced along the length direction of the body (1).

7. The sizing sleeve for manufacturing an axially hollow-wall polyolefin pipe according to claim 6, characterized in that, Every two adjacent groups of vacuum suction holes (16) are arranged in a circumferential dislocation along the body (1).

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