JPS5817019B2 - Netsukaso Seijyusipipe No Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermoplastic resin sheet for forming a relatively thick thermoplastic resin sheet into a cylindrical shape, and welding both end surfaces of the sheet to form a cylindrical body such as a heat insulating pipe. This invention relates to a method of manufacturing a pipe.

As a method for manufacturing such a thermoplastic resin pipe, a thermoplastic resin sheet made of, for example, foamed polyethylene, which has the property of returning to its original shape when external stress is released, is bent so that both sides thereof face each other, and these opposing faces are pressed against each other. The cross-sectional shape of the cylindrical body after heating and melting is changed by heating and melting the cylindrical body while applying a pressure of A method of manufacturing pipes by maintaining them in a flat shape so as to generate pressing stress on the surface was published in Japanese Patent Publication No. 47-464.
Seen in Publication No. 63.

When using this method, the area around the molten part is maintained flat while the molten surface cools, so the formed pipe is deformed into a flat shape, making it difficult to obtain a pipe with a predetermined circular cross section. In particular, since maintaining the flat shape is based on the property of returning to the original shape of the thermoplastic resin sheet, the pipe obtained by this method has a latent force of restoring to the original sheet shape. In pipe insulation work where the pipe wall of the formed pipe is notched in its length direction and the cut is placed over the piping, it is necessary to cut out the pipe wall of the formed pipe in the length direction and then bend the sheet-like open part into a cylindrical shape. It is necessary to wrap the sheet with adhesive tape or the like to prevent it from returning to its original sheet shape. 3. The present invention has been made with attention to these points, and the present invention has been made by focusing on the above-mentioned points, and it is necessary to restore the thermoplastic resin sheet to its original shape through a heating process that attenuates its quality, and a cooling process that maintains the desired shape. In addition, a forming process involving welding and joining of both edges is provided between the heating process and the cooling process, and the sheet joining shape in the forming process has a unique configuration. To provide a method for manufacturing a thermoplastic resin pipe, in which the molded pipe is molded and solidified into a predetermined shape, making it easy to carry out construction such as heat insulation for existing piping, and making it easy to obtain a molded pipe that is reliably formed into a predetermined shape. This is what we intend to provide.

Next, the embodiment of the method of the present invention will be described in detail based on illustrative drawings. 1 is a pipe forming device, and in front of this forming device 1, a guide pipe 2, a heating device 3, and a guide roll 4 are arranged in this order. At the rear of the forming apparatus 1, a pinch roll 5 and a fixed length cutter 6 are arranged in this order.

The forming device 1 sequentially forms a thermoplastic resin sheet 8, such as foamed polyethylene, which is relatively thick and has a property of returning to its original shape when an external stress is released and is wound around a roll 7 into a cylindrical shape. A forming tool 9 and a heating tool 10 for forming
, and subsequently a cooling section 11 forming a cooling zone A.
Above the inner surface of the forming tool 9, there is a flat portion 1.
2 is provided, and 1 is placed at an appropriate location on this flat portion 12.
A relatively thin plate-shaped heating tool 10 having a thickness of about 10 mm is provided so as to protrude inside the forming tool 9.

As shown in FIG.
Consisting of a cooling section 11 with an air-cooled structure,
Further, at the rear of the heating device 10, a cooling portion 14 having an air cooling configuration different from that of the cooling area A is provided.

As shown in FIG. 4, a rotary roll 15 is mounted on the inside of the guide pipe 2, and the thermoplastic resin sheet 8 fed out from the roll 15 is bent in advance into a semicircular shape. The pinch roll 5 has a concave shape in the center as shown in FIG.
It is configured to hold and guide a molded cylindrical body from above and below.

The above apparatus structure is an example of one used to carry out the method of the present invention, and next, a method for manufacturing a thermoplastic resin pipe using the above apparatus will be explained.

First, in the first manufacturing step, the thermoplastic resin sheet 8 wound around the roll 7 is forcibly fed out and moved relative to the molding device 1, and the surface of the fed sheet 8 is heated by the heating device 3.

This heating state is such that the thermoplastic resin sheet 8, which has the property of returning to its original shape when external stress is released, is heated to such an extent that the property of returning to its original shape when external stress is released is attenuated.

Next, this sheet 8 is sent into the guide pipe 2, but in this case, since the rotating roll 15 is adjusted completely horizontally, the opposing surfaces of both side edges of the sheet 8 are heated by the heating tool in the next step. It is bent into a semi-circular shape so as to securely abut both sides of 10.

In this configuration, it is convenient if the rotary roll 15 is mounted so that its angle can be changed so that the level can be adjusted as appropriate.

Then, the sheet 8 heated by the heating device 3 described above is sequentially made into a cylinder shape, and the sheet 8, which is bent into a semicircle with both end faces facing each other, is fed into the forming tool 9 and gradually formed. Opposing surfaces of both side edges abut against each other.

In this abutting state, due to the action of the flat portions 12, the sheet 8 is formed into a substantially semicircular cross-section with both end edges thereof becoming flat surfaces.

Both opposing surfaces of the sheet 8 are brought into contact with each other in a state parallel to each other, and immediately before these opposing surfaces come into contact with each other, both opposing surfaces are heated to a suitable temperature in advance using a heating tool 10. Since both side surfaces are in sliding contact and their surfaces are fused, the opposing surfaces are parallel to each other and completely abutted and welded over their entire surfaces.

After this welding, the welded area is immediately cooled by the air cooling effect of the cooling portion 14.

In the third step following the second step in which the opposing surfaces are welded together, the pipe formed into a cylindrical shape passes through the cooling zone A of the inner portion successively following the flat portion 12. To,
The inner surface of the pipe, which has been corrected into a predetermined shape due to its ability to return to its original shape and the true inner part, and which has been heated to some extent by the heating device 3 in the first step, is cooled, and as a result, this pipe is solidified into a predetermined shape.

The pipe formed in this manner is sent to the fixed length cutter 6 via the pinch rolls 5 and cut into an appropriate length.

The thermoplastic resin pipe obtained by this manufacturing method is
Because it is solidified into a predetermined shape, even if you cut out the pipe wall along its length when using this pipe as a heat insulator to insulate existing piping, it will still remain in its original sheet-like shape. Since the remaining restoring force that tries to return to normal is small, the cross-sectional shape is approximately circular or C-shaped. It is something that can be held and held by the power of form,
This makes insulation work extremely easy.

Note that in the form of an apparatus for carrying out the method of the present invention, heating tool 1
0 has a relatively thin plate-like structure, but this is because if the heating tool 10 is made thick, the heated opposing surfaces will come into contact with the outside air for a long time before they collide, resulting in poor thermal efficiency. Because the material is heated and melted deep, a larger cooling area is required, and this problem is solved.

Further, the flat portion 12 of the forming tool 9 may be substantially flat or elliptical as long as the inner surfaces of the pipe are not in contact with each other.

Furthermore, the cooling region portion may be formed into a substantially perfect circular shape. FIG. 7 shows another cooling area structure, in which the cooling air jetting pipe 16 is inserted into the pipe from the guide pipe 2 side, and the air jetting structure is arranged so that the jetting air does not go around to the heating tool 10 side. It is configured to face the cutter side, and is configured to cool the sheet heating section by the heating device 3 directly from its heating surface.

In this case, the cooling structure formed by the holes 13 formed in the forming tool 9 may be omitted.

Further, as shown in FIG. 6, a flexible sheet 17 is attached to the formed pipe obtained by the above method, and an adhesive tape 1 is further attached.
This shows a pipe with release paper 19 attached to part of 8.
This figure shows the form of a product configured to allow adhesive tape 18 from which the release paper 19 has been peeled off to adhere to a local part of the pipe cut out in the length direction when the pipe is attached to an existing pipe.

In the above apparatus, the pipe is actively cooled to solidify into a predetermined shape after the sheet edges are welded together, but there is no need to cool it with a special cooling device, and natural cooling may be used instead.

Further, in line with the formation of the cooling section, the cooling section may be formed by appropriately cutting out the circumferential portion of the pipe to reduce the frictional resistance with the pipe passing between the sections.
The inner surface of the sheet through which the sheet passes may be treated with a resin or the like having good lubricity, or the forming tool 9 and the cooling section 11 may be made of a material having good lubricity.

Furthermore, these may be constructed of a porous material such as sintered metal to eject gas or liquid onto the contact surface with the sheet to reduce frictional resistance.

In summary, one of the features of the present invention is that it solidifies the molded pipe into a predetermined shape by attenuating the property of the thermoplastic resin sheet to return to its original shape.Based on this idea,
A thermoplastic resin sheet 8 that is relatively thick and has the property of returning to its original shape when external stress is released is continuously formed into a pipe, and first, it has the property of returning to its original shape when external stress is released. Heat to a degree that attenuates, then.

While sequentially forming the sheet 8 under heating into a cylindrical shape,
With both end faces facing each other, the opposing faces are welded together, and after heat welding, the cylindrical shape is corrected into a predetermined shape while cooling and solidifying into the predetermined shape, making it extremely easy to install onto existing pipes. It can be used to form good pipes.
This has led to the provision of a manufacturing method that is extremely effective in manufacturing thermoplastic resin pipes.

Furthermore, the present invention has a second feature in that, when the end surfaces of the sheet 8 collide in the forming process, the entire sheet 8 is formed into a cylindrical body (having a substantially semicircular cross section) and the end surfaces of the sheet are joined together. As a result, both end surfaces of the sheet 8 can be positioned facing each other in a substantially parallel state, and the welding can be performed uniformly and reliably over the entire area of both end surfaces. An appropriate space is formed between the positions of both end faces and the inner surface of the semicircular cylinder formed by the sheet 8 located at the opposing position. Molten resin is prevented from adhering to the inner surface of the semicircular cylindrical body, and the pipe is molded; it is easy to obtain a pipe of a predetermined shape without causing any shape change due to adhesion of resin to the inner surface of the pipe.

[Brief explanation of drawings]

The drawings illustrate an embodiment of an apparatus for carrying out the method for manufacturing a thermoplastic resin pipe according to the present invention, and FIG. 1 is a side view of the molding apparatus;
Fig. 2 is a vertical sectional front view of the main part, Fig. 3 is a cross-sectional bottom view of the main part, Figs. 4 and 5 are longitudinal sectional front views of the main part, and Fig. 6 is a perspective view showing one form of the product. FIG. 7 is a cross-sectional bottom and side view of another structure corresponding to FIG. 3. 8...Thermoplastic resin sheet.

Claims (1)

[Claims] 1. A method for manufacturing a thermoplastic resin pipe, which comprises combining the following steps. (1) A thermoplastic resin sheet 8 that is relatively thick and has the property of returning to its original shape when external stress is released is continuously formed into a pipe, and first, when the external stress is released, it returns to its original shape. The first step is heating to an extent that attenuates the restoring properties. (2) Next, the heated sheet 8 is sequentially deformed into a cylindrical shape, and both end edges of the heated sheet 8 are formed into a cylindrical body having a substantially semicircular cross section, and the flat surface is A second step of welding the opposite end surfaces of the sheets 8 together. (3) After heating and welding, the cylindrical shape is straightened into a predetermined shape, and then cooled and solidified into a predetermined shape.