JPS58191121A - Manufacture of heat shrinkable tube - Google Patents

Abstract

PURPOSE:To enlarge a stock tube to a predetermined diameter holding a uniform section, by attaching a weight to one end of a broad tape, winding another end around the stock tube inside a tubular member through its slit, making said end to be held by an outside winding roll, then rotating the roll and the tube stock and relaxing the broad tape, expanding the tube stock by a fluid pressure. CONSTITUTION:A broad tape member 1 is wound around the outer periphery of a stock tube 3 to be tightened slightly inside the member having a slit 2. Then, the stock tube 3 is heated above its softening point and is expanded in a radial direction by adding a gas or liquid fluid pressure to its inside. In this time a motor 13 is driven and the broad tape member 1 is moved forcibly to the arrow directions, the stock tube 3 is rotated and the radial expansion of the stock tube 3 is controlled by the broad tape member 1. The broad tape member is gradually relaxed, the stock tube 3 is enlarged to a predetermined diameter, cooled and solidified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat-shrinkable tube that shrinks when heated.

In the conventional method for manufacturing heat-shrinkable tubes, a tube made of thermoplastic resin is placed in a cylindrical mold with a predetermined diameter larger than the tube, and liquid or gas is injected into the tube while heating. The material was expanded by applying internal pressure by pushing it in, and when it came into close contact with the inner wall of the mold, it was cooled and solidified. This method is good when expanding at a low magnification, but when expanding at a high magnification, that is, 3 to 10 times the inner diameter of the tube, it expands significantly in the length direction, making it difficult to complete the manufacturing process. When heated and shrunk, the length direction was shrunk to about 2/3 to 1/4 of the length before heating. Heat-shrinkable tubes store items inside and are used for moisture-proofing, dust-proofing, insulation, packaging, etc. by shrinking and sealing the tubes by heating, so it is desirable that the shrinkage in the length direction be small, and the shrinkage in the length direction should be small. The 1/4-longitudinal shrinkage is a problem.

Another method is to insert two rods into a material tube and forcibly expand the material tube by widening the gap between the two rods while heating the rope material tube. This direction allows the production of products with low heat shrinkability in the length direction, but is not suitable for producing products with high magnification or long products in the diameter direction.

That is, the diameter of the two rods must be smaller than the diameter of the material tube, which poses a problem in terms of strength.
A book stick bends and its diameter varies depending on its position in the length direction. This tendency is particularly noticeable in the case of high magnification expansion or long products.

In view of the above points, the present applicant has previously proposed a method for manufacturing a heat-shrinkable tube that eliminates the above-mentioned drawbacks and has a small heat shrinkage in the longitudinal direction and a large shrinkage rate in the diametrical direction. (Special application 1972-
(Refer to No. 172263) This heats the material tube of the heat-shrinkable tube, which contracts when heated, above the softening point temperature, and applies fluid pressure inside the material tube to expand and expand the material tube in the diametrical direction. When the tube is expanded to a predetermined diameter and cooled and solidified to produce a heat-shrinkable tube, the process of expansion and expansion of the material tube in the diametrical direction is controlled through a control means in contact with the outer periphery. This is what I did.

This will be explained below with reference to FIG. Reference numeral 2 denotes a pipe-shaped slit-forming member, and a slit 5 into which the middle portion of the wide tape-like member 1 can be inserted doubly is formed in the axial direction of the material tube 3. One end of the wide tape-like member 1 is fixed to the edge of the slit 5 on the outer periphery of the slit forming member 2 via a wide tape presser 4, and the other end is fixed to the material tube 3 disposed inside the slit forming member 2. After being wound, it is pulled out from the slit forming member 2 through the slit 5.

In the case of manufacturing a heat-shrinkable tube, the wide tape-like member 1, one end of which is fixed to the edge of the slit 5 of the slit-forming member 2, is placed inside the slit-forming member 2 as described above. After winding it around the outer periphery of the tube 3 so as to lightly tighten it, it is taken out from the slit 5 and held on the outer periphery of the slit forming member 2. And material tube 3
is heated through a heating means (not shown) that heats the material of the material tube 3 to a temperature higher than the softening point temperature, and fluid pressure of gas or liquid is applied inside the heated material tube 3 to move the material tube 3 in the diametrical direction. The diameter of the material tube 3 is expanded through an expanding diameter expanding means (not shown).

In this process of expanding the diameter of the material tube 3, the expansion of the diameter of the material tube 3 is controlled by the wide tape-like member 1, that is, the outer diameter is tightened by the wide tape-like member 1, the shape is regulated, and the material tube 3 is gradually slit. It is enlarged by loosening the wide slit-like member inside the forming member 2. Then, when the material tube 3 has been expanded to a predetermined diameter dimension, which is the inner diameter of the slit forming member 2, the material tube 3 is cooled and solidified to complete the manufacturing process. However, the slit forming member 2
It may be cooled and solidified at a predetermined diameter that does not reach the inner periphery. Then, the material Chicove 3 is processed so that the diameter is expanded and expanded while the outer diameter portion is controlled so that the material does not expand in the axial direction at the time of expansion M.

The material for the material tube 2 is not particularly limited, and may include synthetic resins such as polyvinyl chloride, polyethylene, fluorine-based polymers, mixtures or crosslinked materials thereof, polychloroprene, chlorinated polyethylene rubber, and ethylene. Use vulcanized rubber such as propylene rubber.

The wide tape-like member 1 used to wrap the material tube 3 and adjust the expansion rate may be made of any material as long as it has flexibility, heat resistance, and a wide shape. For example, cloth such as cotton cloth, glass cloth, or synthetic fiber, or a cloth treated with rubber or plastic coating, a net made of rope or stainless steel wire, a plastic sheet, a rubber sheet, etc. are used.

The method for producing heat-shrinkable tubes disclosed in Japanese Patent Application No. 54-172263 involves heating a material tube to a temperature higher than its softening point and filling the inside with pressurized fluid to expand and expand the material tube only in a radial direction. Since the outer periphery of the process is controlled through the control means, it is possible to manufacture a heat-shrinkable tube with less heat shrinkage in the length direction and a large shrinkage in the diametrical direction.

However, it has been found that the manufacturing method disclosed in Japanese Patent Application No. 54-172263 has a problem in that the material tube 3 tends to have uneven thickness at the portion 3' of the slit 5 (the thickness tends to increase). This is because the material tube 3 is exposed to the outside air in the section 3- of the slot 5, so the I
i! This occurs because the degree of swelling is small.

An object of the present invention is to provide a method for manufacturing a heat-shrinkable tube that eliminates the drawbacks of the above-mentioned Japanese Patent Application No. 172263/1982 and that can manufacture a heat-shrinkable tube with uniform thickness without uneven thickness throughout. It is in.

That is, the gist of the present invention is to heat a heat-shrinkable tube that shrinks when heated to a temperature higher than the softening point of the material tube, and apply fluid pressure inside the material tube to expand and expand the material tube. In a method for manufacturing a heat-shrinkable tube that is cooled and solidified when expanded to a predetermined diameter, a slit is formed parallel to the axial direction of the material tube to allow the process of expanding the material tube to the diameter direction. On the outside of the tubular slit forming member, a weight for maintaining tension is provided at one end, and the other end is wound around the outer periphery of the material tube placed inside the slit forming member, and then pulled out to the outside of the slit forming member and used as a driving source. This is accomplished while rotating in the circumferential direction by a wide tape-like member held by a winding roll connected to the winding roll.

The above-mentioned wide tape-like member is essentially the same as that in the above-mentioned Japanese Patent Application No. 172263/1982, but considering that it suppresses the elongation of the material tube in the axial direction, the surface It is preferable to use a material with high friction, such as cloth or rubberized material.

Next, the present invention will be explained in detail with reference to FIG. 2 of the accompanying drawings, but it goes without saying that the present invention is not limited to this embodiment. For example, it is not within the scope of the present invention to appropriately increase or decrease the number of tubular slit forming members, etc. used.

In the figure, 2 is a pipe-shaped slit forming member, and a slit 5 into which the middle portion of the wide tape-like member 1 can be inserted doubly is formed in the axial direction of the material tube 3.

Each slit forming member 2 is connected to a tubular matrix 6 at a predetermined interval.
ranged around the circumference of A weight 7 for maintaining tension is provided at one end of the wide tape-like member 1 on the outside of the slit-forming member 2, and the other end is wound around a material tube 3 disposed inside the slit-forming member 2. After being pulled out from the rear slit 5 to the outside of the slit forming member 2, it is connected to a winding roll 11 consisting of a drive roll 8, an idler roll 9, and a follower roll 10.

The drive roll 8 of the winding roll 11 is connected to a drive motor 13 by a chain 12.

14 is a guide roll, and 15 is a guide stand. In the case of manufacturing a heat-shrinkable tube, the wide tape-like member 1 is wound around the outer periphery of the material tube 3 arranged inside the slit forming member 2 so as to be lightly tightened, and then the material tube 3 is wrapped around the material tube 3. Diameter expansion in which the material tube 3 is heated through a heating means (not shown) that heats the material above its softening point temperature, and fluid pressure of gas or liquid is applied inside the heated material tube 3 to expand the material tube 3 in the diametrical direction. Material Chicove 3 via means (not shown)
At the same time, the diameter of the drive motor 13 is expanded.
, the wide tape-like member 1 is forcibly moved in the direction of the arrow, and the material tube 3 is rotated approximately 715 to 415 times.

In the process of expanding the diameter of the material tube 3, the expansion of the diameter of the material tube 3 is controlled by the wide tape-like member 1, that is, the outer diameter is tightened by the wide tape-like member 1, the shape is regulated, and the slit is gradually formed. The material tube 3 is enlarged by loosening the wide tape-like member inside the forming member 2, and at the same time, by forcibly moving the wide tape-like member 1 along the circumferential direction of the material tube 3, the material tube 3 is expanded into a circular shape. Rotated in the circumferential direction. Then, when the material tube 3 is expanded to a predetermined diameter dimension, which is the inner diameter of the slit forming member 2, the material tube 3 is cooled and solidified.

After the material tube 3 has solidified, it is removed from the wide tape-like member 1 and, if necessary, transferred to a cutting device (not shown) for the next step, where it is cut into a desired length to complete the production.

In this way, the method for manufacturing the heat-shrinkable tube of this example is as follows:
The material tube is heated to a temperature higher than its softening point, and the inside of the material tube is filled with pressurized fluid to cause the material tube to expand and expand only in the radial direction, and the outer periphery of this expansion process is controlled by a control means while rotating in the circumferential direction. This makes it possible to manufacture a heat-shrinkable tube that has less heat shrinkage in the length direction, a larger shrinkage in the diametrical direction, and has no uneven thickness around the entire circumference.

Further, in the case of this embodiment, a plurality of heat-shrinkable tubes are simultaneously manufactured using a multi-tube manufacturing apparatus, which is a preferable measure from the viewpoint of mass production.

In the case of this embodiment, the material tube 3 was heated after being placed in the slit forming member 2, but in other embodiments, the material tube 3 cut into an arbitrary length may be heated in an arbitrary manner. After placing the material in a furnace (not shown) and heating it above the softening point temperature, one end of the material tube 3 is sealed, and a fluid pressure sealing stopper (not shown) is attached to the other end. It is also conceivable that this tape is then transferred into the wide tape member 1 within the slit forming member 2 using a feeding device (not shown).

As described above, according to the method for manufacturing a heat-shrinkable tube of the present invention, it is possible to efficiently produce a heat-shrinkable tube that has a small heat shrinkage in the length direction, a large shrinkage rate in the diametrical direction, and has no uneven thickness around the entire circumference. This has the advantage of being easy to manufacture.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of an apparatus for carrying out a conventional method for producing a heat-shrinkable tube, and FIG. 2 is a cross-sectional view of a main part of an apparatus for carrying out a method for producing a heat-shrinkable tube according to the present invention. 1: wide tape-like member, 2 slit forming member, 3: material tube, 4: wide tape holder, 5 slit, 6:
Tubular base body, 7: weight for maintaining tension, 8: drive roll, 9: floating roll. 10: Slave roll, 11: Winding roll, 12: Chain, 13: Drive motor, 14 2nd guide roll, 15 2nd guide stand. Agent Patent Attorney Fujio Sato

Claims (1)

[Claims] When the material tube of a heat-shrinkable tube that shrinks when heated is heated to a temperature higher than the softening point of the material tube, fluid pressure is applied inside the material tube to expand and expand the material tube, and the material tube is expanded to a predetermined diameter. In a method for manufacturing a heat-shrinkable tube that is cooled and solidified, the process of expanding and expanding the material tube in the diametrical direction is performed by applying tension to one end of the outside of a tubular slit-forming member in which slits are formed parallel to the axial direction of the material tube. A holding weight is provided, and the other end is wound around the outer periphery of the material tube placed inside the slit forming member, and then pulled out to the outside of the slit forming member and held by a winding roll connected to a drive source. A method for manufacturing a heat-shrinkable tube, characterized in that this is carried out by rotating a tape-shaped member in a circumferential direction.