JPH0363944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Background and Objects of the Invention] The present invention relates to a continuous manufacturing apparatus for heat-shrinkable resin tubes, which has an improved radial expansion structure when manufacturing resin pipes, generally called heat-shrinkable tubes.

A blowing line that continuously manufactures heat-shrinkable resin pipes is intended to expand and mold raw resin pipes (resin pipe material) only in the radial direction without stretching them in the axial direction. To expand and mold a raw resin tube in the molding section, the temperature of the resin tube must be above its softening point and below its melting point, although it varies depending on the material etc., but generally 100℃.
It is heated and molded to the appropriate molding temperature of ~140℃.
At this proper molding temperature, the raw resin tube is soft to a jelly state, and it is difficult to feed it to the molding section with zero elongation in the axial direction. The present applicant has already applied for a method in which the jelly-like raw resin tube is fed into the molding section in the above-mentioned blowing line with extremely low tension and elongation close to zero. Although this is effective and can be manufactured within certain tolerances, it does not allow for zero axial elongation. That is, when the raw resin tube is expanded and molded in the radial direction in the molding section, the raw resin tube expands in all directions, radial and axial, similar to when a rubber balloon is inflated. Various proposals have been proposed for this molding method, but
In both cases, the balloon state is expanded, so even if the elongation up to the molded part is zero, it is impossible to make the elongation in the axial direction zero. This, of course, is the case when the jelly-like raw resin tube is fed to the entrance of the molding section at an appropriate molding temperature at a constant temperature and under extremely low tension with almost no elongation. Therefore, in the conventional method, it has been difficult to reduce the axial elongation of the raw resin tube to zero during blow molding.

The present invention has been made in view of the above-mentioned circumstances, and provides a continuous heat-shrinkable resin pipe manufacturing device that can manufacture highly accurate heat-shrinkable resin pipes that contract only in the radial direction but not in the axial direction. It is intended for this purpose.

[Summary of the Invention] The continuous manufacturing apparatus for heat-shrinkable resin tubes of the present invention is configured such that a raw resin tube heated in a heating tank is fed, pressurized with compressed gas from the inside, evacuated the outside, and expanded into a finished resin tube. A vacuum chamber, a main cooling washing water tank into which the molded finished resin pipe is introduced and cooled, and a taking machine driven by a motor to take over the finished resin pipe pulled out from the main cooling washing water tank are provided. The finished resin is tightly fitted into the wall of the vacuum chamber on the side of the main cooling washing water tank, and a number of small holes are opened in the tube wall located in the vacuum chamber, and the compressed gas is introduced into the raw resin tube inside. The molded tube in which the tube is formed and the raw resin tube in the vacuum chamber have almost zero elongation in the axial direction and are expanded in the radial direction. A feed roll driven by a motor at high speed to feed the raw resin into the vacuum chamber, and an end position of the forming tube on the outside of the vacuum chamber are located between the vacuum chamber and the main cooling washing water tank, and the above-mentioned The finished resin pipe is loosely fitted to the inner periphery of the molded tube, and the end portion of the molded pipe and the outer periphery of the completed resin pipe are cooled and sealed with lubricating water, and the gap between the outer periphery of the finished resin pipe and the inner periphery of the molded pipe is sealed. A cooling water nozzle for supplying the cooling seal lubricating water jetted into the vacuum chamber from between the cooling water nozzles and the vacuum chamber is provided. That is, in order to synchronize the feed roll speed with respect to the take-up speed with the take-off machine so that it becomes faster by the amount of radial elongation when the raw resin pipe is expanded in the forming pipe, and to reduce elongation after forming. The outer periphery of the completed resin tube at the outlet end of the molded tube is sealed with cooling water, and the cooling water is flowed inside the vacuum chamber between the inner periphery of the molded tube and the outer periphery of the completed resin tube to perform cooling, lubrication, and vacuum sealing effects. It is something.

[Example] The continuous manufacturing apparatus for heat-shrinkable resin pipes of the present invention will be explained below using examples and drawings. The figure is an explanatory cross-sectional view. In the figure, 1 is a heating chamber, 2 is a heating tank, and 3
is a heating medium made of polyethylene glycol, 4
is the feed roll, 5 is the feed drive motor amplifier, 6
is the feed drive motor. 7 is a tachometer generator for the feed drive motor, 8 is a cooling pipe for forming, and 9 is a forming pipe. 10 is a vacuum chamber, 11 is a cooling water nozzle,
12 is cooling seal lubricating water, 13 is a main cooling cleaning water tank, 14 is an air wiper, 15 is a take-up machine, 16 is an amplifier for take-up drive motor, 17 is take-up drive motor, 18 is a tachometer generator for take-up drive motor,
19 is a synchronized speed setter, and 20 is a reference take-up speed setter. In addition, 21 is an original resin pipe, 22 is a finished resin pipe, 23 is a low constant temperature water tank, 24 is a circulation pump, 2
5 is a vacuum pressure gauge, 26 is a vacuum adjustment valve, 27 is a mist separator, 28 is a vacuum pump, 29 is a low pressure control valve, and 30 is an internal pressure gauge.

Then, the raw resin tube 21 discharged from the heating tank 2 in the heating chamber 1 is fed into the vacuum chamber 10 by the feed roll 4 built into the inlet of the forming tube 9, and the part of the forming tube 9 inside is fed into the vacuum chamber 10. While being expanded and stretched in the radial direction, it becomes a completed resin pipe 22 and the cooling seal lubricating water 1
2. It is designed to be taken up by a take-up machine 15 via a main cooling washing water tank 13 and an air wiper 14. In the heating tank 2, the raw resin pipe 21 is heated by the heating medium 3 to a constant temperature suitable for molding.
The heated raw resin tube 21 is sandwiched between feed rolls 4 so as not to slip, and is fed into the raw resin tube 21 from the end of the finished resin tube 22 behind the take-up machine 15 at the formed tube 9 section in the vacuum chamber 10. The molded material is expanded at once by the sum of the heated air (compressed air) introduced into the molded air and the vacuum pressure, and at the same time is molded while being cooled by the molding cooling pipe 8 and the cooling seal lubricating water 12. The cooling water from the cooling water nozzle 11 seals the end of the molded tube 9 on the outer periphery of the completed resin tube 22 and flows from the open end of the molded tube 9 toward the vacuum chamber 10 onto the inner wall of the molded tube 9 and the outer periphery of the completed resin tube 22. Since it is sucked in through the minute gap between the surface and the surface, it plays an important role in the forming operation by acting as a lubricant between the gaps, increasing the cooling effect, and performing a sealing action between the inside of the vacuum chamber 10 and the outside air. is fulfilled.

The reason why the open end of the molding tube 9 is not directly connected to the main cooling wash water tank 13 is to prevent a large amount of water from being sucked into the molding tube 9 at the start (the base resin tube 21 is thin before molding). This is for sealing.
Incidentally, even during operation, a very small amount of this cooling seal lubricating water 12 is sufficient, and by cooling the completed resin pipe 22 and providing sufficient lubrication even during cooling, axial elongation after cooling can be reduced. On the other hand, the essential problem is that when the raw resin tube 21 is inflated within the molding tube 9, it is expanded and molded in all directions, radially and axially, like a balloon. However, at this time, setting the elongation in the axial direction to zero means making the speed of the feed roll 4 faster than the speed of the take-up machine 15 by the proportion of elongation in the axial direction.
This can be achieved by controlling the synchronized speeds of the take-up drive motor 17 and feed drive motor 6, respectively.
In this example, the take-up speed is 5 m/min, and the feeding speed is 5 m/min.
At 5.5 m/min, the axial elongation of the completed resin pipe 22 became zero. Of course, the feed roll speed cannot be made faster than the take-up speed without limit. Although it depends on the material, temperature, speed, size, pressure, etc., in this example, the radial elongation was limited to 200%. At this time, the elongation in the axial direction is "negative" with respect to the elongation direction, that is, it becomes a shrinking phenomenon.

A portion of the molded tube 9 located within the vacuum chamber 10 has many thin holes and communicates with the inside of the vacuum chamber 10. Further, a molding cooling pipe 8 is wound around the molding tube 9, and cooling water is circulated from a low constant temperature water tank 23 via a lubricating pump 24. Water is also supplied from the circulation pump 24 to the cooling water nozzle 11 . The main cooling and cleaning water tank 13 completely cools the finished resin pipe 22 and cleans polyethylene glycol of the heating medium adhering to the surface of the finished resin pipe 22. Air for internal pressurization of the original resin pipe 21 is connected to the finished resin pipe 22 via a constant pressure control valve 29 . The vacuum pressure gauge 25 and the internal pressurization pressure gauge 30 indicate their respective pressures. The take-up machine 15 is driven by a speed control system drive unit composed of a take-up drive motor 17, a take-up drive motor tachometer generator 18, and a take-up drive motor amplifier 16. The feed roll 4 is driven by a drive unit including a feed drive motor 6, a tachometer generator 7 for the feed drive motor, and an amplifier 5 for the feed drive motor, and is operated in synchronization with the take-up machine 15 via a synchronized speed setting device 19. I'm starting to be able to do it. The take-off machine 15 is a speed reference, and the speed of the take-off machine 15 is given by a setting device 20.

On the other hand, the surface of the feeding roll 4 is roughened to the extent that it does not cause any damage to the raw resin tube 21 in order to prevent slipping. Since the feed roll 4 has many sizes of raw resin pipes 21,
In order to suit each size, both the upper and lower rolls can be set at the same distance from the center of the forming tube 9 in a steplessly variable manner, and must be connected to a drive motor in this variable state. For this reason, the connection between the feed roll 4 and the feed drive motor 6 cannot be made using a crank contact, etc. (spring couplings are not possible due to uneven angles), and a special coupling of Schmitt couplings ( (not shown) is attached. The molding inside the molding tube 9 is expanded by constant internal pressure (air in this example) into the expanded resin tube from the rear of the take-up machine 15 and external vacuum pressure at the molding section, but before the feeding roll. It is not expanded because there is no vacuum pressure. As for the forming conditions, it is necessary to set the feeding roll speed, take-up speed, resin tube temperature, cooling water temperature, and vacuum pressure as constant optimum conditions for each size and material of the resin tube.

In this way, the continuous heat-shrinkable resin tube manufacturing apparatus of this embodiment is equipped with a feed roll that is formed to be fed faster than the take-up speed by the amount that it extends in the radial direction, so that when inflating the raw resin tube, it is possible to It is expanded only in the radial direction with almost zero elongation, and is equipped with a cooling nozzle that uses cooling seal lubricating water to seal between the end of the formed tube and the outer periphery of the finished resin tube that is loosely fitted inside the formed tube. As a result, the cooling water is sucked into the vacuum chamber between the inner periphery of the molded tube and the outer periphery of the completed resin tube to create a seal, and also functions as a lubricating fluid to promote cooling of the completed resin tube. Therefore, it is possible to manufacture a highly accurate heat-shrinkable resin tube that contracts only in the radial direction and does not contract in the axial direction.

In the above embodiment, there is one set of feed rolls, but
They may be set in multiple sets or in both vertical and horizontal directions. Further, although the feed roll is set so as to extend to the inner surface of the forming tube at the inlet portion thereof, a structure in which the forming tube is disposed immediately after the feed roll may also be used. In the embodiment, the feed roll has a flat surface and a knurled surface, but for the purpose of centering, grooves are provided only in the center where the resin pipe passes, so that the resin pipe can be properly caught. It's okay.

[Effects of the Invention] As described above, the continuous manufacturing apparatus for heat-shrinkable resin pipes of the present invention has the effect of manufacturing highly accurate heat-shrinkable resin pipes that contract only in the radial direction and do not contract in the axial direction. It is.

[Brief explanation of drawings]

The figure is an explanatory cross-sectional view of an embodiment of the continuous manufacturing apparatus for heat-shrinkable resin pipes of the present invention. 2... Heating tank, 4... Feeding roll, 6... Feeding motor, 9... Forming tube, 10... Vacuum chamber, 11...
...Cooling water nozzle, 12...Cooling seal lubricating water, 1
3... Main cooling washing water tank, 15... Taking machine, 17...
...Take-up drive motor, 21... Raw resin pipe, 22...
Completed resin pipe.

Claims (1)

[Claims] 1. A vacuum chamber where the raw resin tube heated in the heating tank is fed, pressurized from the inside with compressed gas, evacuated the outside, and expanded into a finished resin tube, and the finished resin tube formed above is introduced and cooled. A main cooling washing water tank is provided, and a taking machine driven by a motor that takes over the finished resin pipe pulled out from the main cooling washing water tank is provided. A molded tube that is fitted into the tube and has a large number of small holes opened in the tube wall located in the vacuum chamber, and the compressed gas is introduced into the raw resin inside to form the finished resin tube, and The resin tube is driven by a motor at a speed higher than the raw resin pipe take-up speed of the take-up machine to feed the raw resin into the vacuum chamber by the amount of elongation that causes the resin tube to expand in the radial direction with almost zero elongation in the axial direction. The feed roll and the end position of the formed tube on the outside of the vacuum chamber are located between the vacuum chamber and the main cooling washing water tank, and the completed resin tube is loosely fitted to the inner periphery of the formed tube. Cooling seal lubricating water seals the end of the molded pipe and the outer periphery of the completed resin pipe in the state, and the cooling seal lubricating water is jetted into the vacuum chamber from between the gaps on the outer periphery of the finished resin pipe and the inner periphery of the molded pipe. A continuous manufacturing device for heat-shrinkable resin pipes, characterized in that it is equipped with a cooling water nozzle for supplying cooling water.