JPH0428528A - Continuous production device for heat-shrinkable resin pipe - Google Patents

Abstract

PURPOSE:To prevent the stretching of an original pipe in the longitudinal direction extremely because the original pipe is stretched, and to expand the diameter of the original pipe only in the radial direction by installing a conveyor belt holding the original pipe and being driven at the same speed as that of a delivery caterpillar belt into a heating tank. CONSTITUTION:A conveyor belt 1 mounted into a heating tank B holes an original pipe A fed into the heating tank B and is driven at the same speed as a delivery caterpillar belt D. Support pieces 2 are fitted to each surface of the upper and lower opposed belts 1 at proper intervals in the conveyor belt 1, semicircular sectional support grooves 3 formed to said pieces 2 are abutted against the outer surface of the original pipe A, and the original pipe A is held without being slid. The conveyor belt 1 is driven at the same speed such as 5m/min as the delivery caterpillar belt D.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention involves continuous manufacturing by expanding in the radial direction a tube that is the base of a heat-shrinkable resin tube (hereinafter referred to as the base tube), which is generally called a heat-shrinkable tube. This relates to improvements in equipment.

(Prior art) Conventionally, in order to manufacture a heat-shrinkable resin tube, as shown in Fig. 3, pressurized gas is fed into the resin tube A to maintain the internal pressure of the tube A at a predetermined level. Then, the raw tube A is heated by the heating liquid W in the heating tank B to a temperature above its softening point and below its melting point (generally the appropriate temperature for forming is 100°C to 140°C, depending on the material, etc.), and the raw tube A is made into a jelly-like state. This raw tube A is sent to the tube expansion molding section C by a feeding caterpillar belt D, and by reducing the pressure in the vacuum chamber F in the tube expansion molding section C, the resin tube A is expanded by the differential pressure with the internal pressure. The original tube A was molded into a desired shape while controlling its expansion through a cooling die G provided with a cooling pipe (not shown). The heat-shrinkable resin pipe E thus obtained is, for example,
It is pulled out by the bowed caterpillar belt] 1 shown in the figure.

(Problem to be Solved by the Invention) However, the heat-shrinkable resin tube E expanded by a conventional continuous manufacturing device has a length of 5 to 20% in the longitudinal direction compared to the original length of the original tube A. The heat-shrinkable resin pipe E has been stretched to a certain extent, and the distortion and internal stress remain in the completed heat-shrinkable resin pipe E without being removed.
When thermally shrinking, the shrinkage rate in the longitudinal direction becomes large, which may cause the conductor to be exposed when used in, for example, a connector part. This tendency is particularly strong in the case of the heat-shrinkable resin pipe E having a small diameter, and there is a problem in that its uses are limited.
(Objective of the Invention) An object of the present invention is to provide a continuous manufacturing apparatus for heat-shrinkable resin pipes, which prevents the original pipe from being stretched in the longitudinal direction as much as possible, and expands the diameter only in the radial direction.

(Means for Solving the Problems) As shown in Fig. 1, the continuous heat-shrinkable resin tube manufacturing apparatus of the present invention includes a heating tank B for heating a resin raw tube A, and a heating tank B for heating a resin raw tube A, and an expansion tube for expanding the heated raw tube A. Delivery caterpillar belt D feeding into forming section C
In the heat-shrink resin pipe continuous manufacturing apparatus, a conveyor belt 1 is provided in the heating tank B, which clamps the raw pipe A and drives at the same speed as the delivery caterpillar belt D. It is characterized by:

(Function) When the jelly-like resin base tube heated above its softening point is expanded and molded by introducing pressurized gas, the internal pressure inside the heating tank inflates it like a rubber balloon. Although it extends in all directions including the radial direction and the longitudinal direction, in the continuous heat-shrinkable resin pipe manufacturing apparatus of the present invention, the original pipe A is sandwiched and conveyed by the conveyor belt l provided in the heating tank B. There is almost no elongation of the raw tube A due to the internal pressure in the heating tank B, and since the conveyor belt I is driven at the same speed as the delivery caterpillar belt D, there is no running tension on the raw tube A in the heating tank B. This makes it difficult for the resin pipe A to be stretched in the longitudinal direction.

(Example) FIGS. 1 and 2 show an example of the continuous manufacturing apparatus for heat-shrinkable resin pipes of the present invention.

In Fig. 1, A is the resin raw tube, B is the heating tank, C is the tube expansion molding section, D is the delivery caterpillar belt, E is the heat-shrinkable resin tube, F
is a vacuum chamber, G is a cooling die, and Fl is a drawer caterpillar belt, and these may be the same as conventional ones. W is a heating liquid, and in this example polyethylene glycol is used.

Reference numeral 1 shown in FIGS. 1 and 2 is a conveyor belt provided in the heating tank B. This conveyor belt is
It clamps the raw tube A fed into the heating tank B and drives it at the same speed as the delivery caterpillar belt D.

As clearly shown in FIG. 2, the conveyor belt 1 of this embodiment has support pieces 2 attached at appropriate intervals to each surface of the belt 1 facing upward and downward, and support grooves each having a semicircular cross section formed in the thoracotomy 2. 3 is in contact with the outer surface of the master tube A, so that the master tube A can be clamped without slipping. The conveyor belt 1 of this embodiment is driven at the same speed as the delivery caterpillar belt D, for example, 5 m/mjn. Note that the clamping means for the original tube A of the conveyor belt 1 may be other than the one described above.

Reference numeral 10 shown in FIG. 1 is a heat-retaining liquid nozzle that delivers the heat-retaining liquid, and 11 is a discharge pipe through which the heat-retaining liquid is discharged. This heat-retaining liquid is for keeping the raw tube A between the heating tank B and the tube expansion molding section C warm.

Reference numeral 12 shown in FIG. 1 is a sealing liquid nozzle that delivers sealing liquid into the tube expansion molding section C. This sealing liquid is the original tube A
The outer periphery of the tube and the inlet 14 and outlet 15 of the tube expansion molding section C are sealed to seal the inside of the tube expansion molding section C to maintain a depressurizing effect in the vacuum chamber F, and the tube is sent into the empty chamber F on the same page. It is also a lubricant between the outer surface of prototube A and the inner surface of prototube 14,
Furthermore, it also acts as a lubricant between the cooling die G and the expanded heat-shrinkable resin tube E, and thereby the heat-shrinkable resin tube E after cooling.
It plays an important role in reducing the tension applied to the steel and suppressing its longitudinal elongation.

A very small amount of this sealing liquid is sufficient during continuous operation of the device.

Note that the heating liquid W may be used as the heat retaining liquid and the sealing liquid.

Incidentally, the speeds of the feed-out caterpillar belt D and the pull-out caterpillar belt H must be the same, and if the speed of the draw-out caterpillar belt H is faster than the speed of the feed-out caterpillar belt D, the heat-shrinkable resin Tension is applied to the tube E, causing the heat-shrinkable resin tube E to stretch in the longitudinal direction, and conversely, if the speed of the pull-out caterpillar belt [1] is slower than the speed of the feed-out caterpillar belt D, the artificial part of the tube expansion molding section This causes the original tube A to become slack.

(Effects of the Invention) The continuous heat-shrinkable resin pipe manufacturing apparatus of the present invention has the following effects.

■The conveyor belt installed inside the heating tank allows
The elongation of the raw tube A due to the internal pressure when pressurized gas is supplied in the reheating tank B is suppressed, and since the raw tube A has almost no running tension and is difficult to stretch in the longitudinal direction, the completed heat-shrinkable resin The elongation of tube E in the longitudinal direction is significantly reduced,
A high-quality heat-shrinkable resin pipe E can be provided.

[Brief explanation of the drawing]

Fig. 1 is an overall structural diagram showing one embodiment of the continuous manufacturing apparatus for heat-shrinkable resin pipes of the present invention, Fig. 2 is a detailed view of a conveyor belt used in the same manufacturing apparatus, and Fig. a is a side view. 3 is a front view, and FIG. 3 is an overall structural diagram showing a conventional heat-shrinkable resin pipe continuous manufacturing apparatus. 1 is the conveyor belt A is the raw pipe B is the heating tank C is the tube expansion forming section is the delivery caterpillar belt E is the heat collection w3FM fat pipe W is the heated liquid

Claims (1)

[Claims] A heating tank B that heats the resin raw tube A, and a delivery caterpillar belt D that feeds the heated raw tube A to the tube expansion forming section C.
In the heat-shrink resin pipe continuous manufacturing apparatus, a conveyor belt 1 is provided in the heating tank B, which clamps the raw pipe A and drives at the same speed as the delivery caterpillar belt D. A continuous manufacturing device for heat-shrinkable resin pipes.