JPS5848336B2 - Hogokan oyuusuruhoon Kanno seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously manufacturing a thermal tube having a foamed plastic layer and a protective tube.

Conventionally, methods for continuously forming a foamed plastic layer around the outer periphery of steel pipes, steel pipes, aluminum pipes, and other pipes used for transporting fluids for the purpose of thermally coating them include:
A method disclosed in Japanese Patent Publication No. 46-18231 is already known.

In this method, thermoplastic plastic is extruded into a tube shape from a round die, and foamed plastic is injected between it and an inner tube that is transferred at the same speed to continuously manufacture heat-retaining tubes. has the following drawbacks:

In other words, it is essential that the speed at which the thermoplastic is extruded is the same as the transport speed of the inner tube;
When extruding thermoplastic tubes,
The wall thickness is as thin as 0.5~LOmrn and the outer diameter is 50
If the extrusion speed is higher than A large extruder is required, and the pressure resistance of the round die also needs to be increased.

On the other hand, if the wall thickness is as thick as 3 to 5 mm, cooling after extrusion becomes difficult, so the extrusion speed must be lowered.

Therefore, it is not possible to increase the production rate of heat-retaining tubes.

On the other hand, the foaming of foamable plastics is affected by temperature, and the thermal conductivity changes depending on the diameter and density of the bubbles.

In addition, since the process of extruding the thermoplastic plastic tube at high temperature and then cooling it and the injection foaming of the foamable plastic proceed at the same time, the foaming temperature of the foamable plastic can be adjusted to
It is difficult to arbitrarily and independently select the temperature of the thermoplastic tube serving as the protective tube, and as a result, the quality of the heat retention effect may become unstable.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for manufacturing heat-retaining tubes that solves all of these drawbacks, enables high-speed production, and has a beautiful appearance.

Next, the present invention will be explained in detail using illustrated examples.

1 to 5 show a first embodiment of the present invention, which includes an endless belt consisting of a large number of holding members 10 arranged at regular intervals and links 11 connecting each holding member 10. The linear forward running portions of the pair of belt conveyors 12 and 13 are arranged to extend in parallel in the vertical direction from a horizontal inner pipe transfer center line 14 extending in the axial direction of the inner pipe 6 at equal intervals. , and each holding member 10 in one of the belt conveyors 12 has a groove-shaped formwork 1 consisting of a semi-cylindrical formwork body 15 and a releasable inner layer member 16 fixed to its inner surface extending in the longitudinal direction of the belt. The belt conveyor 12 and each of the grooved forms 1 constitute a belt conveyor 3 with grooved forms.

In each holding member 10 of the other bell 1 and conveyor 13, a grooved formwork 2 consisting of a formwork main body 15 and an inner layer member 16 as described above is arranged so as to extend in the longitudinal direction of the belt, and is attached and detached by bolts. The belt conveyor 13 and each grooved formwork 2 constitute a belt conveyor 4 with a grooved formwork, and the belt conveyor 13 and each grooved formwork 2 constitute a belt conveyor 4 with a grooved formwork.
are synchronously driven in circulation at a constant speed.

The left and right ends and the front end of the inner layer member 16 in one channel formwork 1 protrude from the left and right ends and the front end of the form body 15, and the rear end of the inner layer member 16 is located in the form body. 15, and in the linear forward traveling portion of the belt conveyor 12, the inner surface of the rear end of the formwork body 15 in each adjacent groove-shaped formwork 1 and the outer surface of the front end of the inner layer member 16 is progressively polymerized.

The left and right ends and the rear end of the inner layer member 16 in the other groove-shaped formwork 2 are retracted from the left and right ends and the rear end of the form body 15, and the front end of the inner layer member 16 is retracted from the mold body 15. It protrudes from the front end of the frame body 15, and in the linear forward traveling portion of the belt conveyor 13, the inner surface of the rear end of the frame body 15 of each adjacent groove-shaped form 2 and the outer surface of the front end of the inner layer member 16. and are mutually polymerized.

The grooved formworks 1, 2 attached to the linear forward running portions of each belt conveyor 12, 13 are joined together to constitute a tubular formwork 5, and in this case, one of the grooved formworks 1 The outer surfaces of the left and right end portions of the inner layer member 16 and the inner surface of the left and right end portions of the form body 15 in the other groove-shaped formwork 2 are overlapped with each other.

On the inner tube transfer center line 14 is an annular nozzle 17 for injecting the foamable composition 7 behind the tubular formwork 5.
The front end of the annular discharge slit 18 in the annular nozzle 17 is disposed at the rear part of the tubular formwork 5, and the annular lid 19 for backflow prevention d- is provided at the front end of the annular nozzle 17 and protrudes in the outer circumferential direction. is fixed, and a round die 8 of an extruder for extruding a tube of thermoplastic plastic is provided in front of the tubular form 5 on the inner tube transfer center line 14, and a bell I with each channel form is provided. - A mold cleaning/mold release agent application device 20 is provided opposite to the backward traveling portion of the conveyors 3 and 4.

An inner pipe 6 made of metal such as a steel pipe is continuously transferred forward in the direction of the arrow along the inner pipe transfer center line 14, and a foamable silk material 7 made of a system stock solution in which various components of foamed plastic are mixed and adjusted is The foamable composition 7 is injected from the annular discharge slit 18 in the annular nozzle 17 between the rear part of the tubular formwork 5 and the inner tube 6 and applied to the outer peripheral surface of the inner tube 6, and then the applied foamable composition 7 is Foaming occurs gradually between the tubular formwork 5 and the inner tube 6, and a foamed plastic layer 7' having a predetermined thickness and a predetermined external shape is formed on the outer surface of the inner tube 6.

After the foamed plastic layer 7' formed in this way is hardened, the thermoplastic housing 9 extruded from the annular slit 21 of the round die 8 is placed on the outer surface of the foamed plastic layer 7', and the plastic protective tube 9 ' is formed.

The inner diameter and length of the tubular formwork 5 made up of the channel formworks 1 and 2 are determined by the time required from application of the foamable composition 7 to completion of foaming and curing, and the expansion ratio.

In addition, each groove-shaped formwork 1, 2 is made to sufficiently withstand the reaction heat and pressure accompanying the foaming of the foamable composite material 7, and to be easily released from the mold without adhering to the foamed plastic layer 7'. need to be done.

For example, if the foamable composition 7 is a urethane resin or incyanurate resin and the inner tube 6 is a steel tube, the foamed plastic layer 7' will adhere well to the outer surface of the steel tube, which is a rather preferable property. However, it is desirable that the foamed plastic layer not adhere to the groove-shaped formworks 1 and 2, but rather be easily released from the mold.

Therefore, the inner layer member 16 in each channel formwork 1, 2 is made of a material that is difficult to adhere to the foamed plastic layer 7', such as polyethylene, polypropylene, or Teflon, and the formwork body 15 is made of a material such as steel or aluminum. Use metal or glass such as

A rubber belt may be used as the endless belt of the belt conveyor 12, 13, and the foamable composition 7 is injected into the tubular formwork 5 and the foaming pressure causes the channel formworks 1, 2 to be formed.
Since there is a possibility that the Foamachi Noh Kumihimono 7 may leak from the overlapping part, it is necessary to seal the overlapping part, for example, by rubbing together.

6 to 10 show a second embodiment of the present invention, in which a holding member 10 in a belt conveyor 12, 13 is provided with semi-annular end plates 22 extending in the belt width direction and at both left and right ends. semicircular channel formwork 1 with 23;
2 is removably attached, and a semicircular end plate 22 at one end of one channel formwork 1 has an inverted L [valve 24
An injection hole 25 is provided, and the belt conveyor 1
A large number of independent tubular forms 5 extending in the width direction of the conveyor are constituted by the respective groove forms 1 and 2 attached to the linearly forward traveling portion of the conveyor 213.

A large number of inner tube end fitting recesses 26 arranged at a constant pitch
The upper horizontal portion of the pair of left and right conveyor belt conveyors 27 is arranged so as to extend in the backward direction under the lateral force of both ends of each tubular form 5, and On one side, there is an injection device 2 for injecting the Foamachi Nohsho product.
8 are arranged opposite to each other and fixed at a fixed position, and the injection nozzle 29 of the injection device 28 is configured to be freely inserted into and removed from the injection hole 25 of the semi-annular end plate 22 into the tubular form 5. , and belt conveyors 3 and 4 with each channel formwork.
The conveyor belts 27 and 27 are driven intermittently in circulation at a constant speed over a distance corresponding to the pitch of the tubular forms 5, and the conveyors stop at these belts 1. During this process, the foamable composition 7 is poured into the rearmost tubular form 5.

The inner tube 6, which is supported at both ends by a conveyor belt conveyor 27 and is intermittently transferred forward, is attached to a tubular form 5 by each groove formwork 1, 2 at the rear of the belt conveyor 3, 4 with groove forms. When it is constructed, it is inserted between each channel formwork 1 and 2, that is, it is housed in the rearmost tubular formwork 5 consisting of each channel formwork 1 and 2, and in this state, each The operation of the belt conveyors is temporarily stopped and the required amount of foamable composition 7 is injected from the injection nozzle 29 of the injection device 28 between the tubular formwork 5 and the inner tube 6, and then each belt conveyor is It is moved forward by a distance corresponding to the pitch of the tubular formwork 5.

In this way, the structure of the tubular formwork containing the inner tube and the foaming 6
The injection of the foaming composition, the circulation and driving of each belt conveyor over a fixed distance are repeated, and the injected foamable composition 7 is transferred between the tubular formwork 5 and the inner tube 6 as it is transported forward. A foamed plastic layer 7' having a predetermined thickness and a predetermined outer shape is formed on the outer circumferential surface of the inner tube 6 by foaming gradually between the inner tube 6 and the foamed plastic layer 7' which hardens within the tubular formwork 5.

At the front end of the belt conveyor 3, 4 with grooved formwork, the tubular formwork 5 is divided into the grooved formworks 1, 2, and the foamed plastic cladding tube is taken out from the tubular formwork 5, and then the foamed plastic The cladding tube is transferred laterally and inserted into the round die 8 of the extruder, and the thermoplastic plastic 9 is extruded from the annular slit 21 of the round die 8.
is placed on the outer surface of the foamed plastic layer 7 to form a plastic protective tube 9'.

11 and 12 show a third embodiment of the present invention, in which each holding member 10 of a long lower belt conveyor 13 and a short upper belt conveyor 12 is shown.
Semicircular grooved forms 1 and 2 extending in the belt width direction and having semicircular end plates 22 and 23 at both left and right ends are attached to the belt, and the upper and lower grooved forms 1 and 2 are fitted together. A large number of independent tubular formworks 5 extending in the width direction of the conveyor are constructed, and furthermore, the groove-shaped formwork 2 located at the rear upper part of the lower belt conveyor 13 does not constitute a tubular formwork but opens upward.

A pair of left and right conveyor belt conveyors 27, which are equipped with recesses 26 that support and convey the ends of a large number of inner tubes 6 arranged at a constant pitch, are used to convey the foamable composition 7 before and after foaming. The material travels forward in a straight line until it is cured, and the belt conveyors 3 and 4 with grooved forms and the conveying belt conveyor 27 are continuously circulated and driven at the same speed.

The foamable composition 7 is injected from the injection nozzle 29 between the groove-shaped formwork 2 which is located at the rear upper part of the lower belt conveyor 13 and is open upward, and the inner tube 6 fitted thereto. At the same time, the injection nozzle 29 is traversed from one longitudinal end of the channel formwork 2 to the other end, and the injected foamable composition 7 is transferred to the upper belt conveyor 12 immediately before starting foaming. The groove-shaped formwork 1 attached to the lower groove-shaped formwork 2 is aligned with the lower groove-shaped formwork 2 to form a tubular formwork 5.

The foamable composition 7 is foamed within the tubular form 5. hardens,
Next, at the front ends of the belt conveyors 3 and 4 with channel forms, the tubular form 5 is divided into the channel forms 1 and 2, and the foamed plastic cladding tube is taken out from the tubular form 5.

In this way, the foamable composition is gradually foamed between the tubular form 5 and the inner pipe 6 by the sequential traverse injection of the foamable composition, the grooves of the inner tube-accommodating tubular form, and the continuous driving of each belt conveyor. A foamed plastic layer 7' having a predetermined thickness and a predetermined outer diameter is formed on the outer peripheral surface of the inner tube 6.

Further, the injection nozzle 29 is transported forward by a predetermined stroke at the same speed as each belt conveyor while being traversed,
After the injection is completed, it is moved back to its original position.

13 to 15 show modified examples of the channel formworks 1 and 2, in which a semi-cylindrical formwork body 15 made of metal or glass is coated with an inner layer of polyethylene, polypropylene or Teflon on the inner and outer surfaces. The member 16 and the outer layer member 30 are fixed together, and the left and right side ends and front end of the form body 15 in one channel form 1 are connected to the inner layer member 1.
6 and the left and right ends and front end of the outer layer member 30, and the rear end of the form body 15 is connected to the inner layer member 1.
6 and the rear end of the outer layer member 30.

The left and right ends and the rear end of the form body 15 in the other channel formwork 2 are retracted from the left and right ends and the rear end of the inner layer member 16 and the outer layer member 30, and the form body 15 The front end protrudes from the front ends of the inner layer member 16 and the outer layer member 30, and the front and rear ends of the groove-shaped formworks 1 and 2 arranged in series fit into each other, further forming a tubular formwork. The left and right end portions of the groove-shaped formworks 1 and 2 facing each other are also configured to fit into each other.

Depending on the temperature of the fluid transported inside the inner tube 6, distortion may occur in the foamed plastic layer 7' and cracks may occur. It is preferable to provide an adhesive layer between the protection tube 7' and the protection tube 9' so that they can be well bonded and restrained to each other. In such a case, the adhesive application step may be adjusted.

In the case of the second embodiment as well, each channel formwork 1, 2 is
The laminated interlocking structure shown in FIGS. 5 and 5 or the laminated interlocking structure shown in FIGS. 14 and 15 may be adopted.

Next, examples of this invention will be shown.

(1) Inner pipe material: Steel pipe size: Outer diameter 80 mm x length 5.5 m Transfer speed: 10 m/min (2) Foamable assembly material: Hard polyurethane foam Output rate: 20 kg/min Required time for application and curing :28 seconds (3) Channel formwork (model of the first embodiment) Outer layer member: Steel plate Inner layer member: Teflon tubular formwork? (4) Conveyor length (distance between conveyor rotation axes)
: 5m (5) Thermoplastic composition: High-density polyethylene Discharge pressure: 1 5 okg/CI? L Film thickness: 1.01nr/L (6) Distance between conveyor and round die (distance between conveyor rotating shaft and round die 8): 150CrrL According to this invention, simply a belt conveyor with a pair of grooved formwork 3 and 4, it is possible to automatically configure the tubular form 5 for forming a foamed plastic layer that moves continuously while accommodating the inner tube 6, and to continuously manufacture a foamed plastic cladding tube. Then, by covering the outer surface of the foamed plastic cladding tube with a thermoplastic plastic 9 extruded from a round die 8 of an extruder, a heat insulating tube having a protective tube can be manufactured continuously, and the foamed plastic cladding tube can be continuously manufactured. The process of injecting the plastic composition and foaming and curing it and the process of extruding the thermoplastic plastic 9 to form the protective tube 9' are provided independently.
In the extrusion molding process, the foamed plastic layer 7' is already foamed. Since the thermoplastic protective tube 9' has been completely cured, there is no need for the protective tube 9' of thermoplastic plastic to serve as an external appearance to withstand the internal pressure of foaming and adjust its shape, as in the conventional method, and it is only used as a product to protect the foamed plastic layer 7'. The purpose of this method is different from that of the conventional method, as it serves as a protective tube to prevent damage and moisture absorption.

Therefore, for the thermoplastic plastic 9, it is possible to employ a method that facilitates extrusion molding.

In the case of the conventional method, the extrusion speed from the round die 8 and the molding speed were the same, so the productivity was low, but the method of the present invention has the disadvantage that the extrusion speed from the round die 8 In some cases, the production speed can be increased by increasing the wall thickness and diameter, making the molding speed higher than the extrusion speed, and increasing the drawdown rate. Belt conveyor with formwork 3, 4
The production speed can be further increased by increasing the rotational speed of.

In addition, in the case of this invention, the diameter of the annular slit 18 of the round die 8 can be made larger than the diameter of the molded product, so the pressure loss and shear rate are small, so an extruder with low extrusion pressure can be used and moldability is also improved. Are better.

Furthermore, foamable composition 7 is applied and foamed as described above. Since the curing process and the process of extruding the thermoplastic plastic 9 to form the storage tube 9' are independent, the process of injecting and applying the foaming composition to foaming and curing is performed at the most preferable temperature. Since it can be set as follows, it is possible to obtain effects such as being able to mold a foamed plastic layer with a low quality of directionality.

[Brief explanation of drawings]

1 to 5 show a first embodiment of the present invention, in which FIG. 1 is a partially longitudinal side view showing a state in which a heat insulating tube is manufactured, and FIG. 2 is an A-A 3 is an enlarged side view of a part of the belt conveyor with groove-shaped formwork, FIG. 4 is a sectional view taken along line B-B, and FIG. 5 is C in FIG. 4.
-C line sectional view. 6 to 10 show a second embodiment of the present invention, in which FIG. 6 is a schematic plan view showing a state in which a heat insulating tube is manufactured, and FIG. 7 shows a foamed plastic layer forming section. FIG. 8 is a sectional view taken along the line D-D, FIG. 9 is an enlarged longitudinal front view showing the foamable composition injection part, and FIG.
The figure is an enlarged longitudinal sectional side view showing the protective tube covering part. 11 and 12 show a third embodiment of the present invention, in which FIG. 11 is a partially vertical side view showing a state in which a heat-retaining tube is manufactured, and FIG. FIG. FIG. 13 is a side view showing a modified example of the belt conveyor with grooved formwork, FIG. 14 is a cross-sectional view taken along the line E--E, and FIG. 15 is a cross-sectional view taken along the line F--F in FIG. 14. In the figure, 1 and 2 are channel formworks, 3 and 4 are belt conveyors with channel formworks, 5 is a tubular formwork, 6 is an inner tube, and 7
7' is a foamed plastic layer, 8 is a round die, 9 is a thermoplastic, 9' is a plastic protection tube, 12 and 13 are belt conveyors, 15 is a form body, and 16 is a mold release property. Inner layer member 17 is an annular nozzle, 18 is an annular discharge slit, 25 is an injection hole, 27 is a conveying belt conveyor, 28 is an injection device, and 29 is an injection nozzle.

Claims (1)

[Claims] 1 A pair of belt conveyors 3 and 4 with grooved formworks each having a large number of grooved formworks 1 and 2 are configured to move the tubular formwork 5 forward by the grooved formworks 1 and 2 in the linearly forward traveling portion. A foamable composition 7 is injected between the tubular form 5 and the inner pipe 6 housed therein, and the foamable composition 7 is injected into the foamable composition 7.
is foamed between the tubular formwork 5 and the inner tube 6. By curing, a foamed plastic layer 7' is formed on the outer surface of the inner tube 6, and then a thermoplastic plastic layer 7' is formed on the outer surface of the foamed plastic layer 7' by the thermoplastic plastic 9 extruded from the round die 8 of the extruder. A method for manufacturing a heat-retaining tube having a protective tube, characterized in that a protective tube 9' is formed.