JPS6365016B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-shrinkable tube, and more particularly to a heat-shrinkable tube manufacturing apparatus using an extruded tube as a raw material, and a method for manufacturing the same.

Various methods have been proposed and put into practical use as methods for producing heat-shrinkable tubes made from cross-linked extruded plastic tubes. However, while thin heat-shrinkable tubes are generally easily manufactured using a continuous manufacturing method, thick tubes with an expanded tube outer diameter of several centimeters or more are heat-shrinkable. The expansion and contraction in the length direction that occurs inside the tube poses a major problem in practice, and therefore, it has been manufactured in the form of a regular tube with a length of about 1 to 5 m.

The manufacturing method for this thick heat-shrinkable tube involves inserting multiple rods into a heated plastic tube, moving each rod in the radial direction to create a tube with a polygonal cross-section, and then shaping the tube to a predetermined external size. A mechanical stretching method in which the tube is placed over a repair pipe having a predetermined internal diameter and reheated to contract and form the tube tightly onto the repair pipe, and the heated tube is inserted into a guide pipe having a predetermined inner diameter size.
This method is broadly classified as a gas pressure expansion method in which one end of the tube is closed and gas is injected into the tube from the other end to bring the tube into close contact with the inner surface of the guide pipe. However, in the former case, three steps are required: creating a polygonal tube from the material tube and then shaping it into a predetermined heat-shrinkable tube shape, making the work between each step complicated. Furthermore, the lengthwise distortion of the tube is likely to occur due to the working time between each step, and deterioration of workability and quality deterioration of the completed heat-shrinkable tube cannot be avoided. Even in the latter case, although it is possible to form a heat-shrinkable tube in a substantially desired shape in one step, the expansion due to gas pressure not only stretches the tube in the radial direction but also in the longitudinal direction. Since expansion occurs in the tube, elongation in the length direction becomes uneven due to differences in heating temperature, injection gas pressure, changes in tube wall thickness, etc., making it extremely difficult to manufacture products with uniform properties. Ta. Furthermore, when conventional extruded tubes are used as raw material tubes, no treatment has been performed to remove residual strain in the raw material tubes.
Therefore, the product value as a heat-shrinkable tube was deteriorated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an apparatus and a method for manufacturing the same that can easily and reliably manufacture high-quality heat-shrinkable tubes by eliminating the drawbacks of the prior art as described above.

The gist of the present invention is to fill a material tube with a heated fluid or liquid for uniform heating of the tube, and after the tube has been uniformly heated, to expand its diameter using a mechanical stretching method. The object of the present invention is to manufacture a heat-shrinkable tube having a predetermined shape and characteristics by rotating this enlarged diameter tube in the circumferential direction.Embodiments according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the manufacturing apparatus according to the embodiment of the present invention has an external pipe 2 arranged above a base 1 in a spaced apart manner and parallel to each other. It is rotatably supported by a bearing 3. A gear 4 is fixed to the outer peripheral surface of the external pipe 2, and the external pipe 2 is rotatable in the circumferential direction by a motor 6 via a drive gear 5 and the gear 4. Both ends of the external pipe 2 are essentially sealed internally by a pair of sealing chucks 7a, 7b. One chuck 7 (in the illustrated case, the left chuck 7a) is rotatably supported on the base 1 by a chuck cart 8 that is movable in the pipe axis direction, and is removably sealed with the end of the corresponding external pipe 2. connected. In addition, one chuck 7 (in the case of illustration, the left chuck 7a) has a high temperature tank 9.
The liquid whose temperature has been appropriately raised to heat the material tube stored in the tank 10 and the expansion tube cooling liquid stored in the low temperature tank 10 are connected to the electromagnetic valve V ₁ and
Liquid supply pump 11 selectively supplied by V ₂
A flexible pipe 13 is provided between the chuck and the supply pipe 12, which is rotatable and movable in the axial direction, to inject heating liquid or cooling liquid into the pipe 2. A rotary coupling ring 14a is provided for the purpose. The other chuck 7 (as shown, the right chuck 7)
b) is preferably configured such that the heating or cooling liquid supplied in the pipe is recovered by means of a liquid recovery pump 15 into each corresponding tank 9 or 10 selectively connected by solenoid valves V ₃ and V ₄ ; Flexible tube 1 to accommodate the rotation of
The rotary coupling 14b is connected to the discharge pipe 17 via the rotary coupling 14b.

The liquid supply coupling 14a is equipped with a vacuum pump 18 for creating a substantially vacuum state inside the external pipe 2 so as to facilitate the injection of liquid into the external pipe 2.
are connected in parallel with the supply pump 11 by a suction pipe 19, and the supply pipe 12 of the supply pump 11 and the suction pipe 19 of the vacuum pump 18 are respectively connected to solenoid valves V ₅ and V ₆ to control fluid movement between them. Be prepared. A solenoid valve is installed between the liquid discharge coupling 14b and the recovery pump for similar flow control.
Equipped with _V7 .

Inside the external pipe 2, as shown in FIG. Each claw 7 of a pair of chucks 7a and 7b is provided and is movable in the radial direction.
c and 7d, respectively. Here, it should be noted that each end of the extension bar 20 on the side corresponding to the chuck 7a, which is movable in the axial direction, is removably engaged with the claw 7c of the chuck. As shown in the figure, the engagement between the claw of the chuck and the distraction bar, which is drilled at one end, is achieved by a removable fitting means, and the other side is connected by a fixing means such as a screw. (See Figure 3).

As shown in FIG. 4, one set of stretching bars 20 is formed by a plurality of them (four in the case shown) to constitute one rotating shaft during tube stretching processing, which will be described later. The stretching bar 20 also has a screw thread shape and a screw thread shape on the general axis of rotation at positions corresponding to both ends of the material tube so as to restrict changes in the length direction of the material tube inserted thereon during the stretching process described later. /or protruding stopper 21a, 21b
(See Figure 3).

To create a heat-shrinkable tube using the apparatus according to the present invention configured as described above, first, the movable chuck 7a is moved to open the inside of the external pipe 2, and the claw 7d of the fixed chuck 7b is rotated to a minimum. The material tube 23 is inserted onto the extension bar 20 held at the shaft diameter, the movable chuck 7a is returned to its original position, and each claw 7c of the chuck 7a is
and the extension bar 20 and are coupled to the corresponding end of the pipe so as to seal the inside of the external pipe 2. Here, as shown in FIG. 2, the external pipe 2 is formed to have a suitably larger diameter than the predetermined tube extension diameter, has an outer circumferential surface in contact with the inner circumferential surface of the external pipe 2, and Spacer pipe 22 having an inner peripheral surface corresponding to the expanded diameter
It is preferable to insert the tube into the external pipe 2. This makes it possible to control the final diameter at the time of expansion, which will be described later, and to easily take out the tube at the end of the expansion process.

When the inside of external pipe 2 is sealed, the valve
V ₆ is opened, vacuum pump 18 is started to create a substantial vacuum in pipe 2, valve V ₆ is closed and pump 18 is stopped. Then valve V ₁
After V ₅ is opened and the supply pump 11 is activated to fill the pipe 2 with the heating liquid stored in the high temperature tank 9, the valves V ₁ and V ₅ are closed and the pump 11 is stopped.

When the heating liquid fills the external pipe 2,
The motor 6 is started at a relatively low speed and gradually rotates the external pipe 2 and a pair of chucks 7a and 7b connected to both ends of the external pipe 2 via the gears 5 and 4, and the extension bar rotates together with the external pipe 2. 20 and the material tube 23 inserted thereon are rotated to uniformly heat the tube 23 and eliminate distortions in the material tube remaining due to extrusion molding. When the material tube 23 is heated uniformly and residual strain is removed, the motor 6 is stopped to stop the rotation of the pipe, etc., and each extension bar 20 has a pair of chucks engaged at both ends thereof. By simultaneously gradually moving the claws 7c, 7c radially outwardly by suitable driving means (not shown), the material tube 23 is expanded to a polygonal cross-sectional shape, and the bar 20 and the spacer pipe 22 are When a suitably adjacent position is reached, the movement is stopped (see Figure 5). At this time, the length direction of the tube being expanded is bar 2.
Stopper 21a, 2 provided at the required location of 0
It should be noted that the expansion/contraction change is restricted by 1b, and substantially only the circumferential direction is expanded.

The elongated tube 23 has a polygonal cross-sectional shape,
Valves V ₇ and V ₃ are opened to start the recovery pump 15 and the heating liquid in the pipe 2 is transferred to the high temperature tank 9.
Then, the motor 6 is started to rotate the pipe 2 and the bar 20 at a relatively high speed, thereby causing the liquid in the pipe 2 to flow in a hollow spiral shape, and the centrifugal force caused by this causes the spacer It is formed into a tube having a circular cross-section that contacts the entire inner surface of the pipe 22.

While this rotational movement continues, valves V ₇ and V ₃ are opened and all of the heating liquid in pipe 2 is recovered to high temperature tank 9 by recovery pump 15, and then the recovery flow path is closed and valves V ₂ and V ₅ is opened and the supply pump 11 is activated to rapidly supply the cooling liquid in the cryogenic tank 10 into the pipe 2, thereby cooling and solidifying the expansion heating tube while maintaining its circular cross-sectional shape.

When the tube was cooled and solidified, the supply of cooling liquid was stopped, valves V ₇ and V ₄ were opened, recovery pump 15 was started, and all of the cooling liquid in pipe 2 was recovered into cryogenic tank 10. Afterwards, the motor 6 is stopped to stop the rotation of the pipe 2 and the extension bar 20. Next, after shrinking the extension bar 20 to its original position, the movable chuck 7a is attached to the external pipe 2.
By removing the spacer pipe 22 from the external pipe 2 together with the expanded tube, and extracting the tube from the spacer pipe 22, an expansion tube as a product is manufactured.

Each cross-section of the set of stretching bars 20, which is rotated to expand the polygonal cross-section tube described above to a circular cross-section, is capable of mechanically stretching and fluidically expanding the heated material tube described above, and Any shape can be used as long as it can be configured as the rotation axis of a book, but for example, in the case of a fan-shaped cross-section as shown in Fig. 4, there is a risk that the flow of liquid will be disturbed. Then, as illustrated in the sixth example, a window 20 is provided in the rotation axis side portion of each extension bar 20.
It is also possible to form a hole so as not to impede the flow of liquid.

As described above, according to the present invention, a material tube into which a plurality of stretching bars are inserted is held in a sealed external pipe, and the material tube is first heated with high-temperature fluid supplied into the external pipe. This ensures uniform heating of the material tube and release of residual strain in the material tube during extrusion molding, and prevents unnecessary deformation during the subsequent expansion process. Also,
The diameter of the material tube is expanded efficiently by moving the expansion bar to expand the diameter, and then the tube is shaped with the centrifugal force of the fluid generated by the rotation of the external pipe, making it possible to easily and reliably manufacture tubes of specified dimensions. It is something. Furthermore, since the entire process from the raw material tube to the required heat-shrinkable tube formation can be performed virtually inside the external pipe, almost all manufacturing operations can be automated, and high-quality heat-shrinkable tubes can be produced in a short time. It has great industrial advantages, such as mass production of high-quality heat-shrinkable tubes and cost reduction.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing an outline of a manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view showing a portion of the external pipe of the device shown in FIG. Figure 3 is the second
The figure which shows an example of the engagement relationship of the extension bar and the claw of the chuck shown in the figure. FIG. 4 is an end view along the line of FIG. 2. FIG. 5 is a sectional view similar to FIG. 4 showing the material tube during mechanical stretching. FIG. 6 is a sectional view showing a modification of the extension bar shown in FIG. 4. 2...External pipe, 6...Motor, 7, 7a, 7
b...chuck, 7c, 7d...(chuck's) claw,
9...High temperature tank, 10...Low temperature tank, 11...Liquid supply pump, 15...Liquid recovery pump, 18...Vacuum pump, 20...Tube extension bar, 22...Spacer pipe, 23...Material tube.

Claims (1)

[Scope of Claims] 1. A tube extension bar that is made up of a plurality of tubes that collectively constitute one rotating shaft, an external pipe that concentrically encloses the extension bar in the same axial direction, and an interior of the external pipe. and a pair of chucks provided at both ends of the external pipe to seal and engage each of the extension bars to move them in the radial direction of the center of rotation, and the extension bars, the external pipes, and the chucks are connected to a drive means. The outer pipe is rotatable in the circumferential direction by the chucks and is sealed by the pair of chucks, and the inside thereof includes a heating fluid supply path for uniformly heating at least the tube to be processed, and a heating fluid supply path for uniformly heating the tube to be processed. A cooling fluid supply path for cooling and solidifying the tube and a flow path for selectively injecting the tube as necessary, and at least the heating or cooling fluid injected into the inside of the external pipe as necessary. 1. A heat shrink tube manufacturing device, characterized in that a heat shrink tube is provided with a flow path for discharging the heat. 2. A material tube is inserted onto a single rotating shaft consisting of a plurality of bodies contained in a closed space, and heating fluid is injected into the space to substantially uniformly heat the material tube, The material tube is mechanically stretched by expanding the overall rotation axis diameter in the radial direction, and the sealed space is rotated around the overall diameter expansion rotation axis to shape the mechanically stretched tube into a predetermined size shape. A heat-shrinkable tube characterized in that after the tube is expanded, a cooling fluid is injected into the closed space in place of the heating fluid to cool and solidify the tube having a predetermined expanded size. manufacturing method.