JPH07115408B2 - Resin pipe branching method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a branching portion processing method for forming a branching portion on the wall of a resin pipe such as vinyl chloride.

[Prior Art] When forming a branch portion B as shown in FIG. 5 in a vinyl chloride pipe used for various water supply and sewer pipe lines, particularly in a small-quantity production site, a drawing process is performed by the following procedure. ing.

First, as shown in FIG. 6, a small hole 100 is formed at a position where a branch portion of the peripheral wall of the pipe P is formed. Then, the periphery of the small hole 100 is heated from the inner surface and the outer surface. When the resin becomes soft by heating, as shown in FIG. 7, the cylindrical (or spherical) mold 101 previously inserted inside the pipe P is inserted into the small hole 1
Position it directly below 00 and pull up the mold 101 from the small hole 100. Then, it is lifted up around the mold 101,
The resin on the periphery of the small hole 100 is dragged and rises. Then, by waiting for cooling in this state, the branch portion B is completed.

By the way, conventionally, when heating the inner surface and the outer surface of the resin pipe P, as shown in FIG. 6, the periphery of the small hole 100 is abraded by the flame of the LP gas burner 102.

[Problems to be Solved by the Invention] However, in the method of burning with the burner 102, it is not easy to uniformly heat the portion required for the drawing process, and a portion that is excessively burned or a portion that is insufficiently burned causes defective molding. There was an occasion. In addition, the range of exposure may be too wide or too narrow, which may cause defective molding.

Further, it is difficult to heat the inner and outer surfaces of the resin pipe P at the same time, which causes uneven heating on the inner and outer surfaces, and it takes a long time to heat, resulting in poor work efficiency.

In consideration of the above-mentioned circumstances, the present invention provides a branching portion processing method for accurately, uniformly and efficiently heating a portion required for drawing, thereby efficiently producing a branching portion having good formability. The purpose is to

[Means for Solving the Problem] In the branching portion processing method of the present invention, a small hole is made in the wall of a resin pipe, the periphery of the small hole is heated to soften the resin, and then the resin pipe is inserted. In the method of processing a branched portion of a resin pipe, in which a softened resin around the small hole is raised by pulling up the drawing die from the small hole and then cooled to obtain a branched portion. Using the device and the inner heating device having a planar heater,
At least one of the planar heaters is provided with a hole corresponding to the small hole, and after forming the small hole, an outer surface side heating device and an outer surface side heating device are provided on the inner surface and the outer surface of the resin pipe around the small hole, respectively. Characteristic is that the heater around the small hole is heated from the inner and outer surfaces by both heaters and the heaters of the inner heating device are brought into close contact with each other. After heating, the heater is retracted and the drawing process is performed by the drawing die in that state. I am trying.

[Operation] According to the processing method of the present invention, in heating the periphery of the small hole formed in the pipe wall of the resin pipe, the outer surface side heating device having the sheet heater and the inner surface heating device having the sheet heater. And a hole corresponding to the small hole is provided in at least one of the planar heaters, and after forming the small hole, the outer surface is formed on the inner surface and the outer surface of the resin pipe around the small hole. Since the surface heaters of the inner side heating device and the inner side heating device are brought into close contact with each other to heat the resin around the small holes from the inner and outer surfaces by both heaters, the resin around the small holes can be efficiently heated from the inside and outside, Accurate and uniform heating can be achieved without causing damage to the peripheral edge of the small hole due to heat being accumulated in the small hole, and the drawing process is performed under stable conditions.

[Embodiment] An embodiment of the branching portion processing method of the present invention will be described below with reference to the drawings.

First, the heating devices 10 and 20 shown in FIGS.
Will be described. The inner heating device 10 is shown in FIGS.
As shown in detail in the drawing, it has a substrate 1 curved in a semi-cylindrical shape to be inserted into a resin pipe P. This board 1
Is a semi-cylindrical bent stainless plate.
Since the perimeter of this substrate 1 is actually determined according to the size of the heating target portion, the concept of the “half cylinder” referred to here is that all of the cylinders partially cut away are included. Shall be included.

The substrate 1 of this embodiment is curved so that the central angle θ is about 300 degrees, and its diameter is set to be slightly smaller than the inner diameter of the resin pipe P to be heated. As the material of the substrate 1, a metal plate other than stainless steel, a reinforced plastic plate, or the like can be used. Further, the thickness is not particularly limited as long as it has a restoring property.

A planar heater 3 is attached to the outer peripheral surface of the substrate 1 with a heat insulating material 2 interposed therebetween. As the heat insulating material 2, any material having flexibility such as a foamed material such as plastic or rubber, or asbestos may be used. Further, as the planar heater 3, for example, a silicon rubber heater, a plate-type nichrome heater, or the like may be used as long as it has flexibility and generates heat when energized. When the substrate 1 is made of a material having a heat insulating property such as plastic, the heat insulating material 3 may be omitted.

In addition, between both ends 1A, 1B in the circumferential direction of the substrate 1, both ends 1A, 1B
A cylinder (expansion / contraction diameter means) 4 for expanding or contracting the diameter of the semi-cylindrical substrate 1 by expanding or narrowing the interval is connected. The cylinders 4 are attached to both ends of the substrate 1 in the axial direction in the same manner as shown in FIG. Further, arms 5A and 5B extending toward the center of curvature of the substrate 1 are integrally provided at both ends 1A and 1B of the substrate 1, and the tips of these arms 5A and 5B are located at the center of curvature of the substrate 1. It is rotatably connected to the through shaft 6.

Further, the outer surface side heating device 20 is exactly the same as the planar heater 3 of the inner surface side heating device 10, and has a small hole of the resin pipe P in the center.
A planar heater having holes 20a corresponding to 100 is used. Although the outer surface side heating device 20 is independent, the inner surface side heating device 10 is connected to the drawing die 30 at a constant interval H. Then, when the inner surface heating device 10 is moved, the drawing die 30 is also moved together with it. In addition,
Although the drawing die 30 is connected to the inner heating device 10, it can be freely moved in the drawing direction.

Here, the distance H between the drawing die 30 and the inner heating device 10 is
It is set to be almost equal to the formation interval of the branch portion B.

Next, a method for processing a branched portion using the above device will be described.

In this method, first, a small hole 100 is formed in the pipe wall portion of the resin pipe P where the branch portion B is to be formed. The size of the small hole 100 is about 1/2 of the diameter of the branch portion B. Then, the cylinder 4 of the inner heating device 10 is operated to reduce the diameter of the device 10, and in that state, the heating device 10 is inserted into the resin pipe P and placed on the inner surface of the pipe near the small hole 100. Then, the cylinder 4 is operated to expand the diameter of the device 10 to bring the planar heater 3 into close contact with the inner surface of the pipe P.

Around this, the outer surface side heating device 20 is covered on the outer surface of the tube around the small hole 100. Then, the resin around the small hole 100 is simultaneously heated from the inner and outer surfaces of the tube by both heating devices 10 and 20 arranged on the inner and outer surfaces of the tube P. When the resin is heated to a predetermined softness, both devices 10 and 20 are removed. Inner heating device 10
With regard to (3), the cylinder 4 is operated to reduce the diameter of the device 10 to retract the heater 3.

Then, subsequently, the drawing die 30 is positioned in the small hole 100 that has just been heated, and the drawing process is performed. In this case, the resin heating is performed from the inner and outer surfaces by the planar heater, and since the outer surface side heating device 20 has the hole 20a corresponding to the small hole 100 formed in the pipe wall portion of the resin pipe P, the heat from the inner and outer heaters is generated. Does not stay in the small hole 100, the peripheral portion of the small hole 100 is not overheated and damaged, and the size of the planar heater is set in advance to the size of the heating portion, so that it can be used for drawing. The required area is heated accurately and uniformly without excess or deficiency. Therefore, the drawing process can be performed smoothly under stable conditions, and the branch portion with good quality can be obtained. In addition, since heating is performed from the inner and outer surfaces at the same time, the heating efficiency is very good, and uneven heating on the inner and outer surfaces does not occur, which also improves the formability.

Further, in this embodiment, when the periphery of one of the small holes 100 is being drawn, the inner surface side heating device 10 and the outer surface side heating device 20 are moved and positioned around the adjacent small hole 100, The resin around the small holes 100 is heated at the same time. Then, by repeating this, it is possible to efficiently process the plurality of branch portions lined up at intervals.

Since the inner heating device 10 is connected to the position separated from the drawing die 30 by the distance H when forming the branched portions continuously as described above, the drawing die 30 is positioned in the front small hole 100. Then, the inner heating device 10 is automatically positioned around the next small hole 100, and part of the positioning work is omitted.

[Effects of the Invention] As described above, according to the branching portion processing method of the present invention, the size of each planar heater of the inner and outer surface heating devices arranged on the inner and outer surfaces of the resin pipe is set to the size of the heating target portion. In addition, since at least one of the planar heaters is provided with a hole corresponding to the small hole formed in the resin pipe, the small hole portion of the resin pipe is filled with heat and has a small hole. The heated portion can be heated accurately and uniformly without being damaged due to overheating of the peripheral portion of the. Further, since the drawing is carried out by heating from the inner and outer surfaces, the heating efficiency is good, the drawing can be carried out under favorable molding conditions, and a branched portion with stable quality can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a method for processing a branched portion of the present invention, FIG. 2 is a diagram showing an internal condition of the pipe P shown in FIG. 1, and FIG.
FIG. 4 is a front view of a tube heating apparatus used in the processing method of the embodiment, FIG. 4 is a side view of the apparatus, FIG. 5 is an external view showing an example of a tube having a branch portion, FIGS. 6 and 7. FIG. 6 is a view showing a method of forming a branch portion, FIG. 6 is an explanatory view of a conventional heating method, and FIG. 7 is a view showing a state where the branch portion is being drawn. P ... Pipe to be heated, B ... Branch, 10 ... Inner heating device, 20 ... Outer heating device, 30 ... Extraction type.

Claims (1)

[Claims] 1. A small hole is formed in the wall of a resin pipe by heating the periphery of the small hole to soften the resin and then pulling up a drawing die inserted inside the resin pipe from the small hole. In the method for processing a branched portion of a resin pipe, in which a softened resin is started up and a branched portion is obtained by cooling in that state, an outer surface side heating device having a planar heater and an inner surface side heating device having a planar heater At least one of the planar heaters is provided with a hole corresponding to the small hole, and after the small hole is formed, the small hole is formed on the inner surface and the outer surface of the resin pipe around the small hole. The heater and the hole are made to correspond to each other, and the sheet-like heaters of the outer surface side heating device and the inner surface side heating device are brought into close contact with each other to heat the resin around the small holes from the inner and outer surfaces by both heaters, and then the heater is retracted In that state, pull with a pulling die Bifurcation processing method of the resin tube which is characterized in that the came processing.