JPH06104335B2 - Bending method of partition pipe - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of bending a partition pipe made of a thermoplastic synthetic resin in which a partition wall is integrally molded in the axial direction of the pipe, and more specifically to not only the peripheral wall but also the partition wall. The present invention also relates to a method of bending a partition tube that can be curved to a desired curvature without causing defects such as deformation and wrinkles on its surface.

[Prior Art] A partition pipe 1 made of thermoplastic synthetic resin as shown in Figs. 8 and 9 is used as a protective pipe for burying a covered electric wire. The partition tube 1 includes a tube body (hereinafter referred to as a tube peripheral wall portion) 1b and a tube peripheral wall portion 1b.
One or two or more partition walls 1a arranged along the tube axis direction are integrally formed inside.

As a method of bending the partition pipe 1 having such a shape,
The applicant has previously proposed JP-A-62-279919. The technology of this application is summarized as follows. That is, first, the entire partition tube 1 is immersed in a heating liquid to be softened by heating, a tubular rubber core is inserted into each partition chamber of the partition tube, and compressed air is introduced into the rubber core. The partition pipe 1 is housed in a split outer mold 2 as shown in FIG. 6, and the partition is formed in the curved shaping surfaces 2A and 2B formed on the convex mold 2a and the concave mold 2b constituting the split outer mold 2, respectively. The peripheral wall portion 1b of the attached tube 1 is curved along the peripheral wall portion 1b so as to have a desired curvature.

[Problems to be Solved by the Invention] By the way, when the partition pipe 1 is curved by the above means, it is often experienced that the partition wall 1a is deformed as shown in FIG. 7 (a). It was That is, the partition wall 1a is deformed so as to be compressed in the longitudinal direction of the tube axis on the side close to the bending center O, that is, on the ventral side of the curve with the tube axis (CL) as a boundary, and conversely, it is extended on the back side. The length of each tube in the axial direction is R _L ＞ R _CL ＞ R
It becomes the relationship of _M. However, in the ventral side portion of the partition wall 1a that has been softened by heating, the wrinkle W is generated by the above-mentioned compression deformation.
However, there is a problem in that the smoothness of the inner surface of the pipe is impaired.

Further, if there is a slight difference in the pressure inside the two pipe lines divided by the partition wall 1a inside the pipe, the partition wall is bent and hardened as it is as shown by the broken line portion 1a 'in FIG. 7 (b). There was also the problem of being lost.

Therefore, the present inventors have conducted research for the purpose of establishing a method of bending a partition tube that does not cause defects such as wrinkles W and bending on the partition wall 1a, and completed the method of the present invention.

[Means for Solving the Problems] In the present invention capable of achieving the above object, the first bending method is made of a thermoplastic synthetic resin in which a partition wall along the pipe axis direction is integrally formed inside the pipe body. In the method of bending the partition tube,
With a heat insulating material attached to the surface of the partition wall, by heating the powdered granules into the tube and heating the partitioned tube,
The gist of the present invention is to soften only the peripheral wall of the tubular body to a deformable state, store the curved partitioning tube in a split outer mold having a predetermined curvature, bend it, and then take it out by cooling.

A second bending method is characterized in that a heating fluid is used in place of the above-mentioned powder and granular material, and when the partition tube is housed in the split outer die, the pressure fluid is introduced into the tube body to bend it. Is.

The third bending method is to soften only the peripheral wall of the tubular body to a deformable state by heating the partition pipe with a heating fluid in a state where a heat insulating material is attached to the surface of the partition wall, After adsorbing the outer wall of the partition tube to the curve molding surface and bending the outer wall of the partition tube while accommodating the partition tube in the split outer mold having a predetermined bending and opening the vacuum suction passage at a proper position on the curve molding surface, The idea is to take out after cooling.

The fourth bending method is to heat the partition pipe to soften only the peripheral wall of the pipe body to a deformable state in a state where a heat insulating material is attached to the surface of the partition wall, so that pressure fluid or A vacuum evacuation passage provided on the curved molding surface while accommodating the partition tube in a split outer mold having a predetermined curvature while introducing a heated powder or granular material and maintaining the sectional shape of the partition tube. The gist of the invention is to bend the partition tube by adsorbing the outer wall of the partition tube to the curved molding surface thereof via, and then cooling and taking out after the curve.

[Operations and Examples] Representative examples of the present invention will be described in detail below with reference to the drawings, but the present invention is not construed as being limited to these examples.

FIG. 1 is a perspective explanatory view showing a state in which the heat insulating plate 3 is detachably inserted into the partition tube 1, and the split outer mold 2 is also shown for convenience in the drawing. The heat insulating plate 3 is formed of an arbitrary heat insulating material, and is arranged so as to cover the surface of the partition wall 1a with both surfaces of the partition wall 1a sandwiched therebetween. It is preferable to use a deformable material such as synthetic rubber as the heat insulating material, but if it is composed of a heat insulating material that is difficult to deform such as foamed polymer or cooling copper plate, remove it just before bending as described later. Such a case is not excluded because a method of quickly and quickly completing the bending process can be adopted. Then, a heat medium, for example, hot air H is uniformly blown onto the outer and inner circumferences of the partition pipe 1, but since the partition wall 1a is protected by the heat insulating plate, only the pipe peripheral wall portion 1b is heated to a deformable temperature. To be done. Although the heating temperature does not limit the present invention, for example, in the case of a polyvinyl chloride resin partition pipe, the pipe peripheral wall portion
It is desirable to heat 1b to about 140 ° C. Although the temperature of the partition wall depends on the heat insulating capacity of the heat insulating material, it is desirable that it is slightly heated in consideration of the ease of bending, and in reality it will be somewhat due to the internal heat transfer of the synthetic resin pipe material itself. Is heated to, for example, 70 to 90 ° C. near the shaft core. In particular, as shown on the right side of FIG. 2, it is advantageous to form a temperature gradient T such that the temperature gradually increases as it approaches the tube peripheral wall portion 1b from the vicinity of the shaft core portion.

In addition to the method of heating the partition tube 1 by hot air, a method of filling powdered material such as heated sand into the pipeline 1A of the partition tube or heating the partition tube by immersing it in a high temperature liquid You may employ the method of doing.

Then, in the next step, the heated partition tube 1 is housed in the split outer mold 2, and the outer peripheral surface of the pipe peripheral wall portion 1b is curved along the curved shaping surfaces 2A and 2B of the outer mold to a predetermined curvature. Let At this time, the temperature of the partition wall 1a is not heated to the softening temperature, but since the temperature distribution as described above is exhibited and part of the temperature is increased to a deformable temperature, following the above-described bending process. It is curved and does not cause the wrinkles W and bending as described above. Since the heat insulating plate 3 is in contact with both surfaces of the partition wall 1a, it is expected that the contact will exert an action of preventing the generation of wrinkles W. Further next (a) ~
It is also possible to add any of the means of (C) to process the entire partition tube 1 smoothly.

That is, for the purpose of maintaining the cross-sectional shape in the pipe, (a) as shown in FIG. Or means for filling with heated sand or the like, or JP-A-62-279
Like No. 919, a tube-shaped rubber core is inserted into each hollow portion of the partition tube 1, and means for feeding compressed air into the rubber core is added.

For the purpose of improving the followability between the outer wall of the partition tube and the molding surface of the outer mold, (b) as shown in FIG. 5, a vacuum drawing passage 6 is formed in the outer molds 2a and 2b.
And means for sucking the outer peripheral surface of the tube peripheral wall portion 1b to the curved molding surfaces 2A, 2B through the vacuum evacuation hole 6a, the chamber 6b and the evacuation piping 6c.

(C) Use the methods of (a) and (b) above together.

The partitioning tube 1 curved by the split outer mold 2 is naturally cooled while being stored in the split outer mold, or the outer pipe 2
Of the partition tube 1 and / or the pipe 1A of the partition tube 1 to forcibly cool the partition tube 1 to cool and harden the partition tube 1 in a curved state, and then divide the outer mold 2 into curved tubes. Take out.

As described above, when the outer wall is used to perform the bending process without completely softening the entire partition wall 1a, the partition wall 1a is contracted and stretched in the minimum necessary amount at an appropriate position. No defects such as wrinkles were generated on the surface of 1a, and it became possible to perform curved processing on a smooth surface. Further, since the partition wall 1a is not completely softened, the partition wall is not bent even if a slight pressure difference occurs between the two conduits.

INDUSTRIAL APPLICABILITY The present invention is applicable not only to the polyvinyl chloride two-pipe pipe shown in the above example, but also to all thermoplastic synthetic resin pipes such as polyethylene pipe and polypropylene pipe, and the partition pipe 1 It can also be applied to the 4-pipe pipe shown in FIG. 3 and other plural pipe pipes. At this time, the shape of the heat insulating plate 3 is made to match the arrangement shape of the partition wall 1a as shown in FIG.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, defects such as wrinkles and bends do not occur in the partition wall, and buckling of the pipe wall portion does not occur. The whole can be efficiently curved to a desired curvature.

[Brief description of drawings]

FIG. 1 is a perspective explanatory view showing a heating process of a partition pipe according to the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a cross section showing another example of the partition pipe. FIGS. 4 and 5 are cross-sectional explanatory views showing an example of bending processing by a split outer die, FIG. 6 is a perspective explanatory view showing an example of bending processing of a partition pipe by a conventional method, and FIG. 7 (a) is a conventional method. Fig. 7 (b) is a cross-sectional explanatory view showing an example of a defect in the conventional method, and Figs. 8 and 9 are perspective views of a partition pipe made of thermoplastic synthetic resin. . 1 ... partitioned pipe, 2 ... divided outer mold 3 ... insulation plate, 4 ... blocking lid 5 ... pressure fluid introduction lid, 6 ... vacuum drawing passage

Claims (4)

[Claims] 1. A method of bending a partition pipe made of a thermoplastic synthetic resin, which comprises integrally molding a partition wall along the pipe axis inside a pipe body, wherein a heat insulating material is attached to the surface of the partition wall. By heating the partition tube by filling a heated powder or granular material into the tube, only the tube peripheral wall of the tube body is softened to a deformable state, and the inside of the split outer die having a predetermined curvature is formed. A method of bending a partition tube, wherein the partition tube is housed, bent, cooled, and then taken out. 2. A method of bending a partition pipe made of a thermoplastic synthetic resin, which comprises integrally forming a partition wall along the pipe axial direction inside a pipe body, wherein a heat insulating material is attached to the surface of the partition wall. By heating the partition tube with a heating fluid, only the peripheral wall of the tubular body is softened to a deformable state, and the partition tube is housed in a split outer mold having a predetermined curvature. A method for bending a partitioned pipe, which comprises bending while introducing a pressure fluid into the pipe, then cooling and taking out. 3. A method for bending a partition pipe made of a thermoplastic synthetic resin, wherein a partition wall extending in the axial direction of the pipe is integrally molded inside the pipe body, wherein a heat insulating material is attached to the surface of the partition wall. By heating the partition tube with a heating fluid, only the peripheral wall of the tubular body is softened to a deformable state, and the vacuum drawing passage is opened at a proper position on the curved molding surface having a predetermined curvature. A method of bending a partition tube, wherein the partition tube is housed in a separate outer mold, the outer wall of the partition tube is adsorbed to the curved molding surface to be curved, and then cooled and taken out. 4. A method for bending a partition pipe made of a thermoplastic synthetic resin, wherein a partition wall extending in the axial direction of the pipe is integrally formed inside the pipe body, wherein a heat insulating material is attached to the surface of the partition wall. , By heating the partition tube to soften only the peripheral wall of the tube body to a deformable state, introducing a pressure fluid or heated powder or granular material into the tube body to change the sectional shape of the partition tube. While retaining the partition tube in a split outer mold having a predetermined curvature while maintaining the state, the outer wall of the partition tube is adsorbed to the curve molding surface via a vacuum passage provided in the curve molding surface. Thus, the method for bending a partition tube is characterized in that the partition tube is curved, and after the curve, the tube is cooled and taken out.