JPS6223727A - Manufacture of heat-shrinkable tubing - Google Patents

Abstract

PURPOSE:To obtain the heat-shrinkable tubing with low cost by a method wherein one end of a continuous plastic tube is sealed and gas pressure is applied from the other end of the same while the tube is introduced into a diameter expanding device from one end thereof to expand the diameter thereof and cool it sequentially in every given length. CONSTITUTION:The plastic tube 2a is would around a reel la and one end thereof is sealed while gas pressure is being applied from the other end thereof. The plastic tube 2a is introduced into the diameter expanding device 3 and a metallic tube 4 as well as the metallic tube 5 for jacket are conducted to heat them simultaneously, then a pressure is applied to the inside of the tube to expand the diameter of the tube while cooling medium is introduced into the jacket to cool it after finishing expansion of diameter, then, the tube is advanced by a length, for which the cooling is finished, and this operation is repeated sequentially. Thus, the plastic tube 2b, whose diameter is expanded already, is reeled around a take-up reel 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) This invention relates to a heat-shrinkable tube that can be conveniently used for connecting tWR cables, plastic pipes, and the like.

(Prior art) (Problems to be solved) Conventionally, when manufacturing this type of heat-shrinkable tube, for example, a method has been proposed that involves full extrusion of plastic and then putting it in a diameter expanding device to expand the diameter. It is suitable for manufacturing items with a diameter of about 10 to 20 m, but it is suitable for manufacturing items with a diameter of about 100 W,
Furthermore, it is not necessarily an efficient method, especially in the case of cross-linked plastics.

Based on this provision, if a normal plastic tube can be manufactured in advance by extrusion and the diameter enlarged to give it heat shrinkability can be carried out efficiently, it is still not clear whether it is a preferable manufacturing method other than extrusion. Preferred means have not yet been created.

(Means for Solving the Problems) The present invention was developed as a result of various studies in order to solve all the above-mentioned problems. is sealed, gas pressure is applied from the other end, and one end is led into a diameter expanding device, and within this diameter expanding device, expansion and diameter expansion and cooling are performed sequentially for each foot length.

This diameter expanding device has a double groove structure consisting of an inner metal tube that determines the outside diameter of the plastic tube and an outer metal tube for the jacket that is coaxially provided on the outside of the inner metal tube. This device is capable of heating and cooling at the same time by passing a cooling medium between the inner and outer metal tubes during cooling.

(Example) To explain the invention with reference to the drawings, as shown in FIG. 1, a normal plastic tube 2a manufactured by extrusion is wound around a reel 1a.

One end is sealed and gas pressure is applied to the other end. and such plastic tube 28 full diameter expansion device 3
Within 4 @ 710 heat expansion, advance by 9 to finish cooling, and repeat the same operation in sequence. In this way, the plastic tube 2b, which has been expanded and expanded in diameter every reel lbt, is wound up on the take-off side.

The details of the diameter expanding device are as shown in Fig. M2, and the metal tube 4 for forming and the metal tube 5 for jacketing are coaxially constructed so that both can be electrically heated at the same time. In addition, 6 is an insulating member, 7 a # 7 b is a front and rear seal part, 8 is a passage for the cooling medium to the metal tube for the jacket, 9 is drained with a bell mouth, and the plastic tube is expanded as shown by the imaginary line from the English spelling. Weigh the processed metal.

When processing using this device, if the pressure on the outside of the plastic tube is P1% above the pressure on the inside, then @initially P1≧P! Then, when expanding the diameter, PI<P2 is maintained and maintained. During this diameter expansion, the plastic tube is heated by the heat generated by the double tube, so heating is more uniform and efficient than in the case of a single tube.Furthermore, once the diameter expansion is complete, a cooling medium such as cooling water is completely passed through the jacket. It is possible to cool efficiently by just using

In the first stage of the actual expanding tube expansion process, as shown in Figure 3, the end s'fr of the tube is pulled out from the metal tube 4 of the expanding device 3, and then the end s'fr is pulled out for engraving. ,
Although the front seal part 7b' is required, it will be easily understood that for the next part onward, the seal part 7b can be removed and the same operation repeated as shown in FIG. 4.

In the application of the present invention, it is preferable to heat crosslinked plastics to a temperature above the melting point, and non-crosslinked plastics to a temperature below the melting point but above the softening point.

(Effects of the Invention) As the diameter of the present invention can be expanded using a simple method as described above, shrinkable tubes can be produced at low cost, and by selecting the heating temperature, plastic particles and crosslinking can be avoided.
Regardless of K\, it is possible to produce a whole tube with uniform absorbency ft.

[Brief explanation of drawings]

Fig. 1 is a detailed explanatory diagram of the present invention, Fig. 2 is a longitudinal cross-sectional view showing an example of the diameter expanding device used in the present invention, and Fig. 3 is a diagram showing the initial machining process of the diameter expanding tube. Longitudinal cross-sectional view, culvert 4
The figure is a partial vertical cross-sectional view showing the processing state from the second time onwards. 2a... Original tube 2b... Product tube 3゛... Diameter expansion device 4... Metal tube for forming 5... Metal tube for jacket 8... Cooling medium passage agent Patent attorney Bamboo Uchi no kami figure 1

Claims (1)

[Claims] In a method for continuously manufacturing heat-shrinkable tubes, one end of a long plastic tube is sealed, gas pressure is applied from the other end, the tube is introduced into a diameter expanding device, and the length of the tube is expanded and expanded and cooled one by one. , consists of a double structure: an inner metal tube that determines the outer diameter of the plastic tube as a diameter expansion device, and an outer metal tube for a jacket installed coaxially on the outside of the inner metal tube.
A method for manufacturing a heat-shrinkable tube, characterized by using a device that can perform heating and cooling alternately by applying electricity to both metal tubes during heating and passing a cooling medium between the inner and outer metal tubes during cooling.