KR19990068371A - Device of manufacturing a heat shrinkable tubing - Google Patents

Abstract

The present invention relates to a heat shrink tube manufacturing apparatus.

According to the present invention, a polyolefin containing LDPE or LLDPE and containing some additives is extruded into a pipe of a desired size and crosslinked by irradiating with chemical crosslinking or high energy transmission radiation, and then heating and expanding the crosslinked pipe to heat-shrink the tube. In the manufacture of the present invention relates to a device for manufacturing the intermediate wall and rear wall heat shrink tube using the bag expansion method, there is no eccentricity, there is little shrinkage in the longitudinal direction during the shrinkage construction to produce a beautiful heat shrink tube.

Description

Device for manufacturing heat shrinkable tubing

TECHNICAL FIELD The present invention relates to an apparatus for manufacturing medium and heavy wall heat shrink tubes, and more particularly, to an apparatus for producing a heat shrink tube by expanding a crosslinked polyolefin pipe by bag expansion.

In general, thermoplastics consist of very long and very thin molecules arranged irregularly. The strength of these thermoplastics largely depends on the distance between the molecules and the crystallinity of the molecular structure. These thermoplastics, when heated, collapse the crystal structure (when it reaches a softening point) and can be shaped into any desired shape. Cooling after forming a certain shape recrystallizes and gives the material a significant strength. On the other hand, when the heat is applied again, the crystals disappear and melted and flowed out, and the original form cannot be maintained.

However, exposure to high-energy transmissive radiation such as X-rays, beta rays, and gamma rays to these thermoplastics with the discovery of atomic energy results in permanent bonding between adjacent molecules, commonly referred to as cross linking.

The crosslinked thermoplastic material does not melt or flow at temperatures above the softening point. When the crosslinked thermoplastic material is heated to the softening point, the crystals disappear as before the crosslinking, but the new bonding structure due to the crosslinking causes the elastomer to act like a string between the molecules. Therefore, it does not flow or deform anymore.

One of the products using the property that the cross-linked material is not deformed by heat is a heat shrink tube that is widely used in the industrial field, such as electricity, electronics, the manufacturing sequence of such a heat shrink tube.

(1) A pipe of various diameters is extruded using a polyolefin material to produce a pipe.

(2) The pipe manufactured as described above is crosslinked by crosslinking or light irradiation by a chemical method.

(3) The crosslinked pipe is heated to a temperature above the softening point.

(4) Inflate the heated pipe by the shrinkage calculated by the experiment.

(5) It cools in the expanded state as mentioned above.

(6) The cooled shrink pipe is separated from the production equipment, cut and packed to standard dimensions to complete the product.

Such heat shrink tubes are classified into ultra thin wall tubes, thin wall tubes, medium wall tubes, and heavy wall tubes according to the wall thickness t.

The conventional manufacturing method for the intermediate wall or the rear wall tube has been manufactured by using the manufacturing principle of the thin film tube as it is or by rotating a compression roller by sandwiching a cross-linked polyolefin heat shrink tube between two longitudinally long rollers.

However, when the heat shrink tube is manufactured by the roller compression manufacturing method as described above, the heat shrink tube is stretched not only in the radial direction (lateral direction) but also in the longitudinal direction (longitudinal direction), so that the shrinkage in the longitudinal direction during heat shrinkage is increased. It is so large that it is very inconvenient to use. That is, for example, when the heat shrink tube is to be contracted to cover a certain length, there is a problem in that the shrinkage ratio is calculated in advance to cut the length longer by the shrinkage rate.

In addition, the longitudinal shrinkage of the heat-shrink tube is usually required to be within 7%, the roller compression manufacturing method has a problem that the longitudinal stretching rate exceeds 7%.

In addition, the roller compression manufacturing method has a problem that it is difficult to rapidly cool after expanding the heat shrink tube to a desired dimension, and therefore, it is difficult to manufacture a uniform product due to natural shrinkage phenomenon after processing.

Another conventional apparatus for manufacturing a heat shrink tube is an apparatus for manufacturing a heat shrink tube by continuously passing an expansion tube. The apparatus has to blow compressed air from the inlet or outlet side of the tube to expand the crosslinked polyolefin tube, which is inconvenient to blow compressed air over the entire length of the tube and has a very low productivity due to the high failure rate. In addition, in order to pull out the tube, PET tape had to be adhered to the tube in advance and the drawer had to be drawn out.

Another conventional manufacturing apparatus is a tube manufacturing apparatus by the vacuum method, which expands the tube by the vacuum suction force, there is a fear that eccentricity occurs because the vacuum is not uniformly applied to the tube to be processed, the quality This is uneven and has the disadvantage of being unsuitable for high to high expansion rates of two to one or more.

Therefore, the present invention was devised to solve the above problems, and drilled several air holes in a metal pipe of a predetermined length with one end closed, and made an air bag with a coated special fabric, and then the metal pipe. After fixing to both ends, the object is to provide an apparatus for manufacturing a heat shrink tube to inflate air into the open inlet of the pipe to expand the air bag to expand and shape the polyolefin tube.

The above object according to the invention is achieved by the apparatus for producing heat shrinkable tubes by the air bag expansion method of the present invention, which is closed at one end and equipped with an air hose coupling at the other end and air outlet holes over the entire surface. A metal pipe which is perforated and movable left and right by a sliding mechanism; It is formed to have a certain diameter and is made of a special fabric with a special coating to prevent the air injected into the surface. Both ends are fixed to both ends of the metal pipe, and when air is injected into the pipe, the air expands to a certain diameter. Expansion bags; The expansion bag has a diameter to enter (lower inner diameter up to 12mm) and has an inner surface in contact with the heat shrink tube inserted into the expansion bag and to prevent the generation of bubbles in contact with the heat shrink tube and the inner surface An internal expansion tube having a plurality of holes perforated and having an air channel attached to the outside by welding or the like for inducing air discharge from the holes; Achievable by the heat shrink tube manufacturing apparatus of the present invention having a cooling tube having a cooling water inlet and an outlet through which cooling water is introduced and discharged at upper and lower portions, which are fixed by both end covers and form a water jacket at a predetermined distance from the inner expansion tube. do.

1 is a view showing a pre-compression state of a roller compression manufacturing method of a heat shrink tube according to the prior art.

Figure 2 is a view showing a state after the compression of the roller compression manufacturing method of the heat shrink tube according to the prior art.

Figure 3 is a view showing a small diameter heat shrink tube manufacturing apparatus passing through the expansion tube in accordance with the prior art.

Figure 4 is a view showing a large diameter heat shrink tube manufacturing apparatus passing through the expansion tube in a continuous manner according to the prior art.

5 is a view showing a vacuum heat shrink tube manufacturing apparatus according to the prior art.

6 is a view showing a metal pipe used in the heat shrink tube manufacturing apparatus according to the present invention.

7 is a view showing an expanded state in which the air expansion bag is attached to the metal pipe according to the present invention.

8 shows an internal expansion tube according to the invention.

9 is a view illustrating a coupling relationship between an internal expansion tube and a cooling tube.

10 is a side view of the device according to the invention.

11 is a cross-sectional view showing a heat shrink tube device according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10 metal pipe 11: air hose coupling

12, 15: air hole 13: air expansion bag

14 internal expansion tube 16 air channel

17: fastening bolt 18: end cap

20: cooling tube 21: cooling water outlet

22: cooling water inlet

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 is a view showing a heat shrink tube manufacturing apparatus by roller compaction according to the prior art.

First, referring to FIG. 1, a crosslinked polyolefin tube 3 is sandwiched between two adjacent coarse and thin pairs of rollers 1, 2. As shown in FIG. 1, the polyolefin tube 3 having a thick wall and a short length is rotated while pressing the two rollers 1 and 2 with each other, and as shown in FIG. 2, the polyolefin tube 4 is shown. As the wall thickness of the thinner is thinned, it is produced in the desired diameter while being stretched in the longitudinal (longitudinal) and radial (lateral) directions.

The completed heat shrink tube stretched in both directions as described above is contracted by the length stretched at the time of contraction, and in particular, the contraction in the longitudinal direction is a problem because the excessive shrinkage in the application of the heat shrink tube is difficult, rapid cooling is difficult .

3 and 4 is a view showing a small diameter and large diameter heat shrink tube manufacturing apparatus continuously passing through the expansion tube according to the prior art. Reference numerals to the same parts will be described using the same numbers throughout the two figures.

The crosslinked polyolefin tube (3) is passed through the heating bath (5) while the tube is heat-softened to the middle portion and thereafter expanded by compressed air flowing from the outlet end side of the tube to increase its diameter. The expanded tube is then cooled by a cooling medium while passing through the cooling bath 6 to maintain and maintain the diameter of the cooling tube. At this time, the PET tape 8 is attached to the outer circumferential surface of the tube and drawn out by the four rollers 7 for pulling out the cooled tube. This continuous expansion tube tube manufacturing apparatus has to blow the compressed air in the direction of the arrow from the inlet or outlet side of the tube, it is inconvenient to blow the compressed air over the entire length of the tube and the productivity is very low due to the high failure rate. In addition, in order to pull out the tube, the PET tape 8 has to be adhered to the tube 3 in advance and has to be drawn out to the roller 7.

5 is a view showing a vacuum tube manufacturing apparatus according to the prior art. From the right side of the device, the tube 3 enters the heating bath 5, gradually heats up and softens, and reaches the vacuum expansion tube 9, under negative pressure from a vacuum source connected from the outside, thereby expanding the tube and expanding the tube. 6) it is cooled and discharged by extrusion of the pair of rollers 7. However, the drawback of the vacuum method as described above is that since the vacuum is not uniformly applied to the tube, an eccentricity occurs and the quality is uneven, and it is unsuitable for high rate expansion.

6 shows a metal pipe 10 according to the invention. The metal pipe 10 is preferably composed of a metal such as aluminum. One end of the metal pipe 10 is closed so that air does not leak. The other end of the metal pipe 10 is equipped with an air hose coupling 11. The air hose coupling 11 is connected to an air source such as an air pump. The front surface of the metal pipe 10 is perforated with air holes 12 at regular intervals or randomly. Although not shown in the drawing, the air hose coupling 11 is provided with a slide mechanism that can move horizontally from side to side.

FIG. 7 shows the expanded state of the air expansion bag 13 according to the invention which is fixed to both ends of the metal pipe 10 shown in FIG. 6. The air expansion bag 13 is fixed to a portion adjacent to both ends of the metal pipe 10 by using a tightening mechanism such as a hose clamp. The air expansion bag 13 is made of a special fabric with a special coating to prevent the leakage of air. Special fabrics are cut into squares, folded and sewn to make cylindrical shapes. In such a case, since there may be a leak of air in the seam portion, after making two air bags, the seam may be arranged so that they do not overlap. In addition, it is better to use a cylindrical weaving in order to eliminate the sewing line portion when weaving a special fabric. In such a case, one or two layers may be used.

8 shows an internal expansion tube 14 according to the invention. A plurality of holes 15 are drilled in the internal expansion pipe 14, and a plurality of U-shaped air channels 16 covering these holes 15 are attached by welding or the like. The air channel 16 is for preventing air bubbles formed between the inner wall of the expansion tube 14 when the air expansion bag 9 is expanded by air injection to expand the heat shrink tube. If bubbles are generated, the surface of the heat shrink tube becomes rugged to prevent this. The air channel 16 is for preventing the cooling water in the cooling tube 14 from entering. A plurality of fastening bolts 17 (only one of which is shown for brevity) is fixed to the end of the internal cooling tube 14. The inner diameter of the inner expansion tube 14 should be determined so as to have a diameter plus the natural shrinkage of the heat shrink tube to be completed.

9 is a view showing a state in which the fastening bolt 17 of the internal expansion pipe 14 pipe is screwed by the end cap 18 and fixed to the cooling pipe 20. A predetermined number of fastening bolts 17 are attached to the internal expansion pipe 14, and the same number of fastening bolt through-holes are formed in the end cap 18, and fastened tightly by fastening the nuts. A plurality of air holes 15 are perforated in the inner expansion pipe 14 and covered by the air channels 16. Although there are a plurality of air channels 16 installed, only one of them is shown in the drawing.

10 is a side view of the device according to the invention. An end cap 18 is installed on the side of the device, and two rows of through holes 19 are formed at regular intervals on the periphery of the end cap 18. The holes in the outer row are the holes for the cooling tube 20. The holes are holes for the internal expansion tube 14. A cooling water outlet 21 is attached to the top of the apparatus, and a cooling water inlet 22 is attached to the bottom of the apparatus.

11 is a cross-sectional view of a device according to the present invention, wherein the cooling tube 20 is formed to form a water jacket larger than the diameter of the inner expansion tube 14 shown in FIG. 8 and having a predetermined distance from the inner expansion tube 14. ). Cooling water discharge pipe 21 is coupled to the upper portion of the cooling tube 20, the cooling water inlet 22 is formed at the lower portion. Cooling water is introduced through the cooling water inlet 22 located at the lower portion of the cooling pipe 20 to cool the heat shrink tube through the water jacket, and then is discharged to the outside through the cooling water outlet 21 formed at the upper portion.

Referring to Figure 11 looks at the operation sequence of the heat shrink tube of the present invention.

The internal expansion pipe 14 is a fastening bolt 17 through the cooling inlet 22 in the state in which the cooling pipe 20 is fastened and assembled by the end cap 18 through the outlet 21 through the outlet 21 Discharged. At this time, after the heated polyolefin tube is inserted into the air expansion bag 13, the metal pipe 10 is pushed into the internal expansion pipe 14 through the slide mechanism. Then, when air is injected through the air hose clamp 11, the air expansion bag 13 is expanded by the injection air to expand the polyolefin tube. The expanded polyolefin tube is in close contact with the inner wall of the inner expansion tube 14, wherein air remaining inside the inner expansion tube 14 is discharged through the air hole 15 and is discharged to the outside through the air channel 16. . As the polyolefin tube is expanded as described above, the polyolefin tube is cooled by cooling water to determine the inner diameter of the heat shrink tube by the air expansion bag 13, and the outer diameter of the heat shrink tube is determined by the inner diameter of the inner expansion tube 14. When the cooling is confirmed that the air pipes are slightly lowered and the metal pipe 10 is pulled out from the internal expansion pipe 14 to separate the heat shrink tube from the air expansion bag 13. The separated heat-shrink tubing is cut and packaged to specification and the manufacture is complete.

The apparatus for manufacturing a heat shrink tube according to the present invention configured as described above has the following effects.

-A heat shrink tube having a relatively small elongation in the longitudinal direction (longitudinal direction) can be manufactured, which satisfies a 7% longitudinal elongation tolerance.

-When using heat shrink tube, it can be used without having to calculate the longitudinal shrinkage.

In the roller compression manufacturing method, rapid cooling is difficult, but the present invention has an effect of cooling the tube at about the same time as the tube expansion.

In the roller compression manufacturing method, the heat shrink tube tends to be bent irregularly due to the natural shrinkage phenomenon, the present invention can be produced a uniform product.

Claims (3)

One end is closed, the other end is equipped with an air hose coupling 11, the air hole 12 is perforated at regular intervals or randomly over the entire surface, and the metal pipe 10 which can be moved left and right by a slide mechanism )Wow; It is formed to have a certain diameter and is made of a special fabric with a special coating to prevent the air injected into the surface, and both ends are fixed to both ends of the metal pipe 10, and when air is injected into the pipe, An inflated air bag (13); Have an inner surface in contact with the cross-linked polyolefin tube inserted into the air expansion bag 13 and having a diameter in which the air expansion bag 13 can enter and to prevent generation of bubbles upon contact with the polyolefin tube and the inner surface An internal expansion tube (14) having a plurality of holes (15) for drilling and having a plurality of air channels (16) attached to the outside by welding or the like for inducing air discharge from the holes (15); Cooling pipe having a cooling water inlet 22 and an outlet 21 fixed by both end caps 18 and having a predetermined distance from the internal expansion pipe 14 to form a water jacket, and having coolant flowing in and out of the upper and lower portions thereof. A heat shrink tube manufacturing apparatus characterized by having a (20). 2. The apparatus of claim 1, wherein the air expansion bag (13) has a seam or is woven into a tub. The apparatus for manufacturing a heat shrink tube according to claim 1, wherein when the air expansion bag (13) is formed by sewing, the sewing line is overlapped with one or two layers.