JP3199396B2 - Processing method of branch pipe joint and surface contact heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a branch pipe joint of a synthetic resin pipe and a surface contact heater used for the method.

[0002]

2. Description of the Related Art For example, in a sewer pipe or the like, a branch pipe joint used for branching a branch pipe from a main pipe made of a synthetic resin has conventionally used a predetermined length of a main pipe material as a raw pipe.
The branching method is as follows: 1) a method in which a perforated branch is softened by heating using a gas converter or the like, and is drawn using a predetermined drawing die. 2) A saddle is bonded to the perforated branch to branch. 3). Various methods such as welding a branch pipe and reinforcing the surroundings with, for example, FRP coating, 4) or heat-softening the entire raw pipe with a gas burner or the like and performing blow molding using a predetermined outer mold are performed. .

[0003] Among these various methods, due to their man-hours, cost, watertightness (waterproofness), flexibility and other reasons, 1)
And the blow molding method of 4) are often used.

[0004]

However, in this type of conventional blow molding, the heating is
This is a method in which the entire raw tube is heated by a gas burner or the like from the outside.
It is inevitable that the temperature distribution and the heating range become non-uniform, and a local thinning phenomenon may occur at the time of molding in the next step.

Further, even if a method of locally heating only a necessary portion is adopted, it takes a long time for heating due to external heating by a burner or the like, and uneven temperature cannot be avoided. The same applies to the case of the drawing method.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional method, and heats only a required minimum portion of a branch portion from the inner and outer surfaces of a raw pipe in a locally uniform manner. An object of the present invention is to provide a processing method for obtaining a high-quality branch joint and a plate-shaped surface contact heater used for the same, while shortening the time from softening to the next step forming.

[0007]

For this reason, according to the present invention, in the branching process of a synthetic resin branch pipe joint, plate-shaped electric heaters are provided which respectively contact the inner and outer surfaces of a local pipe to be branched. After setting and heating and softening,
The object is achieved by adopting a method of performing the following molding step.

Each of the heaters on the inner and outer surfaces of the tube is configured such that a plate-like heater on which electric heater wires are wired is coated with a heat-resistant resin or rubber-based material, and that a plurality of or a single opening is provided between the wires. By doing so, the next molding step is to be facilitated.

[0009]

According to the above-described heating and softening method using the surface contact heater, the minimum necessary branch portion is evenly heated from the inner and outer surfaces of the pipe, so that the time required for the heating is short, and high-quality branch processing can be obtained. , Productivity also improves. In addition, a single opening provided in each plate heater enables
Can occur if there is no opening on the hole for the branch of the original pipe
This prevents the heater in this part from overheating ,
In the case of the blow molding method, the inner heater can be formed by applying the internal pressure without damaging the heater by using a plurality of openings provided in each plate-like heater in a case of the blow molding method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a process explanatory view of one embodiment of the blow molding method according to the present invention. (A) is a cross-sectional view of a state where a plate heater is mounted on the outside / inside of the original tube, (b) is an end view for explaining how to mount the plate heater, and (c) to (e) show the subsequent process sequence. 2 (a) and 2 (b) are plan views of two examples of this type of heater.

Reference numeral 1 denotes an original tube of a predetermined length made of a synthetic resin for making a branch joint, and 2/3 each abut the outer / inner surface of the straight tube 1 to locally heat only the branch portion. It is a plate-shaped (panel-shaped) outer / inner heater. Each heater 2,
3 is basically the same structure, and as shown in FIG. 2, the upper and lower portions of the electric resistance heating wires wired in parallel at a fine pitch in a planar shape are each made of a heat-resistant resin-based or heat-resistant rubber-based insulating material ( For example, in FIG. 3A, a plurality of openings 11 are equally provided
(B) shows one relatively large opening 11a at the center.
Are drilled. As described below (a) the figure for blow molding, (b) figure shows a pultrusion.

These heaters 2 and 3 are respectively shown in FIG.
The outer tube 1 is attached in close contact with the outer / inner surface of the original tube 1 by the method shown in FIG. That is, the outer heater 2
The steel coil spring 4 or a band or the like is attached to each side of the circumferential surface, and is attached and fixed by the fixture 4a so as to surround the outer periphery of the original tube 1. On the other hand, the inner heaters 3 are connected to each other by, for example, a stainless steel plate 5 having a length in which both ends in the circumferential direction are united with the heater 3 and in close contact with the circumferential surface of the original tube 1. A knob 5a is fixed to the portion (that is, the diameter-facing portion of the heater 3), and a pair of axial hinge portions 5b is provided on both circumferential sides thereof.
When the knob 5a is pulled toward the center of the raw tube 1, the arc-shaped steel plate portion up to the hinge portions 5b on both sides is elastically buckled and deformed inward to reduce the total straight diameter. In this state, the position of the heater 3 is adjusted.
By pressing the knob 5a against the tube wall, the heater 3 can be mounted in close contact with the inner diameter.

In this state, as shown in FIG. 3 (c), each end plate 6 is pressed against both ends of the original tube 1 by, for example, an oil pressure or the like to be sealed. An electric wire 7 for the inside heater 3 is hermetically penetrated through one end plate 6, and is provided with a pressure air introduction pipe 8 for blow molding. The outer heater 2 is independently connected to a power supply wire (not shown). In this state, the branch portion is locally uniformly heated and softened by the outer / inner heaters 2/3, and then the outer heater 2 is removed as shown in FIG. When the outer mold 9 is mounted / fixed to the outside and pressurized air is introduced from the air introducing pipe 8, the branch portion of the softened raw tube 1 is pressurized through each opening 11 of the inner heater 3, and the branch portion is formed by the outer mold. 9 expands and deforms, and when the outer mold is removed, the branch portion receiving port 1a is formed as shown in FIG. After curing, the end plate 6, the inner heater 3 and the like are removed to complete the branching process. The branch portion formed in a disk shape can be opened using, for example, a hole saw or the like, and can be used as a receiving portion.

(Other Embodiment) FIG. 3 is an explanatory view in which this type of blow molding method is applied to a pipe branch header.
(A) is a cross-sectional view of a case having a two-branch portion, and (b) is a cross-sectional view of a case having a three-branch portion immediately after completion of molding.
(C) The figure shows each end view, and
2, the same (corresponding) components as those in FIG.
Duplicate description is omitted. In the drawing, reference numerals 9a and 9b denote mounting members and fixing bolts of the outer mold 9, respectively. Also, 12,12
a is each spacer, and by using a spacer of an appropriate length, a desired branch pipe interval l ₁ , l _2, etc. can be obtained.

[0015] FIG. 4, the case of the pultrusion process in place of the blow molding of the embodiment, the outer / inner heater 2/3, having a single aperture 11a that shown in FIG. 2 (b) Here is an example of using. In this case, since a relatively large-diameter hole 1b for a branch pipe is formed in the original pipe 1 in advance, the presence of the openings 11a of the heaters 2 and 3 may cause this portion if the openings 11a do not exist. Phenomenon such as overheating of the heater can be prevented. In the case of this drawing method, after heating / softening, the heater is removed from both the upper and lower two-thirds and then passed through a drawing die (not shown) in the direction of arrow 13 to branch pipe portion 1a.
Is molded.

The electric heaters used in each of the above embodiments are not necessarily limited to the processing of this type of branch pipe joint, but can be applied to other similar processing methods.

[0017]

As described above, when forming a branch portion in a synthetic resin raw tube, the necessary minimum portion is evenly heated from the inner and outer surfaces of the tube, so that the heating time is short and high. High quality branching is obtained and productivity is improved. In addition, a single opening provided in the plate-shaped heater allows
In the case where there is no opening on the hole for the branch of the original pipe
In this case, it is possible to prevent the heater in this portion from being overheated, and to form a plurality of openings provided in each plate heater, in the case of the blow molding method , so that the blow molding can be performed while the inner heater is left. .

[Brief description of the drawings]

FIG. 1 is a process explanatory view of one embodiment of a blow molding method.

FIG. 2 is a plan view of two embodiments of a plate heater.

FIG. 3 is an explanatory view of another embodiment of FIG. 1;

FIG. 4 is a process explanatory view of one embodiment of a blanking forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original tube 2/3 Outside / inside plate heater 10 Heater wiring 11, 11a Opening

Claims (3)

(57) [Claims] In a branching process of a synthetic resin branch pipe joint, plate-shaped electric heaters are provided to abut on inner and outer surfaces of a local pipe to be branched, and are heated and softened. A method for processing a branch pipe joint, comprising performing a forming step. 2. A heat-resistant resin-based or heat-resistant rubber-based material is coated on the upper and lower surfaces of an electric heater wire wired in a plate shape so as to abut against the inner and outer surfaces of a local portion of the synthetic resin tube to be softened. A surface contact heater comprising a plurality of openings. 3. A branch pipe provided beforehand in a synthetic resin pipe.
Abuts the inner and outer surfaces of the local pipe to be softened around the hole
Heat-resistant resin above and below the electric heater wiring
And heat-resistant rubber-based material, and
Surface characterized by having a single opening in the corresponding part
Contact heater.