JPH0796266B2 - Method for manufacturing deformed pipe joint made of synthetic resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a synthetic resin deformed pipe joint used for connecting pipe materials having different diameters in a piping operation.

(Prior Art) Conventionally, as a method for manufacturing a deformed joint of this type, a method called a welding method as shown in FIGS. 7 to 10 has been known. 7 and 8 show a general method for manufacturing a deformed pipe joint in which the pipe axes of the large diameter portion and the small diameter portion are the same, and FIGS. 9 and 10 show the large diameter portion and the small diameter portion. 6A and 6B are half cross-sectional views respectively showing a manufacturing method of an eccentric variant pipe joint in which a step between and is almost eliminated.

In any of the above-mentioned deformed pipe joints, this welding method first processes three short pipes and forms them into respective parts of a large diameter portion a, a tapered portion b, and a small diameter portion c (Figs. 7 and 9). Then, these parts a, b, c are joined by welding d ... And processed into a deformed pipe joint.

In addition to such a manufacturing method, an injection molding method is known in which a desired shape is formed at once.

(Problems to be Solved by the Invention) However, in the above-described conventional welding method, it is necessary to previously form three parts of the large diameter portion a, the tapered portion b, and the small diameter portion c, and Since each of these parts must be joined one by one, there is a problem in that manufacturing takes time and labor. Further, since the three parts are joined by welding, the resulting deformed pipe joint has a long overall length, which makes it difficult to connect the pipe material during piping, and is also inferior in mechanical strength and dimensional accuracy. There was also.

On the other hand, the injection molding method does not have the above-mentioned problems of the welding processing method, but on the other hand, the cost of the mold required for the molding is high, and the deformed pipe joint is generally produced in a large variety and in a small quantity. There is a problem that the manufacturing cost per unit becomes very high.

(Means for Solving the Problem) A method for manufacturing a synthetic resin deformed pipe joint according to the present invention is one end portion of an original pipe made of synthetic resin having the same diameter as the larger diameter of the deformed pipe joint to be manufactured. While softening by heating, a cylindrical mold having an inner surface shape substantially the same as the outer surface shape of the modified pipe joint to be manufactured is heated to a temperature equal to or higher than the softening temperature of the raw pipe, The original pipe is forcibly inserted from the softened portion thereof, and the softened portion of the original pipe is reduced in diameter to be molded into a deformed pipe joint.

(Operation) When the original pipe is forcibly inserted into the mold from its softened part, the original pipe enters while rubbing against the inner wall surface of the mold, and the softened part follows the inner surface shape of the mold. After being deformed and reduced in diameter, the tapered portion and the small diameter portion are molded in one step.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 are process drawings, FIG. 5 and FIG. 6 showing an embodiment of a method for manufacturing a synthetic resin deformed pipe joint according to the present invention.
The figure is a cross-sectional view showing a mold used in the manufacturing method of the present invention.

The raw pipe 1 is a short pipe made of synthetic resin having the same diameter as the larger diameter of the deformed pipe joint 6 to be manufactured. Examples of the synthetic resin include hard vinyl chloride resin and heat-resistant vinyl chloride resin. A thermoplastic synthetic resin is preferably used.

On the other hand, the die 2 is a tubular shape having an inner surface shape that is substantially the same as the outer surface shape of the modified pipe joint 6 to be manufactured. Fifth
The mold shown in the figure is a mold used for manufacturing a general deformed pipe joint in which the pipe axes of the large diameter part 21 and the small diameter part 23 are the same, and the mold shown in FIG. It is a mold used for manufacturing an eccentric deformed pipe joint used when the retention of fluid in the pipe joint is disliked. The angle (angle of inclination of the inner surface of the taper portion 22 with respect to the inner surface of the large diameter portion 21) θ of the taper portion 22 of these molds 2 is preferably in the range of about 15 degrees to 20 degrees. If this angle θ is smaller than 15 degrees, the total length of the pipe joint becomes unnecessarily long, which is not preferable, and if it is larger than 20 degrees, the softened portion 11 of the raw pipe 1 buckles during molding. It is to be noted that the mold 2 thus configured has only to have its inner surface molded into the above-described shape.

Next, the manufacturing method of the present invention will be described.

First, as shown in FIG. 1, the lower end of the raw tube 1 is placed in a heating medium 3 (for example, glycerin) 4 heated in a heating tank 3 to a temperature sufficient to soften the synthetic resin of the raw tube 1. Soak part for a certain period of time and heat. The submerged range l ₁ is a range corresponding to the small diameter portion 63 of the odd-shaped pipe joint 6 to be manufactured.

When the above fixed time has elapsed, as shown in FIG.
The raw tube 1 is further submerged in the heating medium 4, and heating is continued for a certain period of time again. The submerged range l _{2 in} this case is a range corresponding to the tapered portion 62 of the modified pipe joint 6 to be manufactured.

As described above, one end portion of the raw pipe 1 is heated in two stages to be softened, while the mold 2 is heated to the softening temperature of the synthetic resin of the raw pipe 1 or higher. By raising the temperature of the mold 2 in this way, when the raw pipe 1 is fitted into the mold 2, the softened part of the raw pipe 1 is cooled and the fitting cannot be prevented.

Then, the raw tube 1 is taken out from the heating tank 3 and is placed on the plate body 5 with the softened portion 11 facing up. Then, the original pipe 1 is covered with the mold 2 from the large diameter portion 21 thereof, an inclusion (not shown) is applied to the upper end of the mold 2, and an impact load is repeatedly applied from above the original pipe 1, The tube 1 is forcibly inserted into the mold 2 (see FIG. 3).

As described above, the original pipe 1 is fitted into the mold 2 by a predetermined size,
After cooling in that state, the original pipe 1 is pulled out from the mold 2, and the whole process is completed. The deformed pipe joint 6 molded in this way is shown in FIG. If the mold 2 shown in FIG. 6 is used instead of the mold 2 in the above process, an eccentric variant pipe joint can be molded.

By the way, in the above-mentioned embodiment, an impact load is applied to the mold 2 to insert the raw pipe 1 into the mold 2, but this causes a great frictional resistance between the mold 2 and the raw pipe 1. Since the original pipe 1 is large and the amount of deformation of the original pipe 1 is large (the diameter is reduced and the thickness is increased at the same time), the softened portion 11 of the original pipe 1 will be buckled by simply pressing the mold 2. is there. In addition, raw tube 1
The one end part of the pipe joint 6 is divided into two parts, that is, the part l ₁ which becomes the small diameter part 63 of the pipe joint 6 and the part l ₂ which becomes the taper part 62. Also, since it is necessary for the raw pipe 1 to have a high hardness so that the raw pipe 1 does not bend or bulge at the inlet of the mold 2 due to frictional resistance with the mold 2, one end portion of the raw pipe 1 is simply Small diameter part 63 that has the largest amount of deformation by only softening 63
This is because it becomes difficult to mold the portion l ₁ that becomes.

Next, in carrying out the production method of the present invention, specific examples of molding conditions when a hard vinyl chloride resin is used as the synthetic resin of the raw pipe 1 are shown in Table 1, and when a heat-resistant vinyl chloride resin is used. Table 2 shows specific examples of molding conditions.

In Tables 1 and 2, the immersion time is
ranges immersion time of l ₁ and the total time of the immersion time in the range of l _2, preferably approximately equal to the immersion time in the range of immersion time and l ₂ in the range of l _1. That is, for example, in the case of a hard vinyl chloride resin, for a raw pipe having a nominal diameter of 50 mm, the immersion time in the range of l ₁ is 50 seconds and the immersion time in the range of l ₂ is 50 seconds.
Seconds.

Next, the tensile strength, the bending strength, and the Charpy impact value of the deformed pipe joint manufactured by the manufacturing method according to the present invention and the deformed pipe joint manufactured by the conventional welding method were measured. The results are shown in Table 3.

From the above results, the deformed pipe joint manufactured by the manufacturing method of the present invention is superior in all respects of tensile strength, bending strength and Charpy impact value to those manufactured by the conventional welding processing method. You can see that

(Effects of the Invention) As described above, according to the method for manufacturing a synthetic resin deformed pipe joint according to the present invention, since it is possible to manufacture from a single raw pipe, it is possible to significantly increase compared with the conventional welding process. In addition, the time and labor required for processing can be shortened, and the length of the pipe joint does not become unnecessarily long, so that the pipe joint convenient for pipe connection work can be obtained. Further, since the large diameter portion, the tapered portion, and the small diameter portion are integrally molded, it is possible to obtain a deformed pipe joint excellent in mechanical strength and dimensional accuracy. Furthermore, since the mold has a simpler structure than the mold used in the conventional injection molding method, the mold becomes cheaper and the manufacturing cost can be suppressed.

[Brief description of drawings]

1 to 6 show an embodiment of a method for producing a synthetic resin deformed pipe joint according to the present invention. FIGS. 1 to 4 are process drawings, and FIGS. 5 and 6 are molds, respectively. Cross section showing
7 to 10 are half sectional views showing a conventional welding method. 1 …… Original pipe 11 …… Softened part 2 …… Mold 6 …… Deformed pipe joint

Claims (1)

[Claims] Claim: What is claimed is: 1. One end portion of a synthetic resin raw pipe having the same diameter as the larger diameter of the modified pipe joint to be manufactured is heated and softened, while the outer surface shape of the modified pipe joint is to be manufactured. A cylindrical mold having substantially the same inner surface shape is heated to a temperature equal to or higher than the softening temperature of the raw pipe, and the raw pipe is forcibly fitted into the mold from the softened portion thereof, A method for manufacturing a synthetic resin deformed pipe joint, characterized in that the softened portion of the is deformed to form a deformed pipe joint.