JPH0733061B2 - Different diameter pipe joint manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a different-diameter pipe joint used for connecting different-diameter pipes to each other in piping work.

(Prior Art) Conventionally, as a method for manufacturing this kind of different-diameter pipe joint, a method called a welding method as shown in, for example, FIGS. 5 and 6 is known.

In this welding method, first, three short pipes are processed into respective parts of a large diameter part a, a tapered part b, and a small diameter part c, and then these parts a, b, c are joined by welding d. Then, it is processed into a different diameter pipe joint.

Further, in order to reinforce the welded portion of the one thus formed and processed, an uncured fiber reinforced synthetic resin (FRP) layer is formed on the outer peripheral surface of a certain dimensional range with the welded portion at the center. A method of heating and curing is also known.

On the other hand, in addition to the above-described manufacturing method, an injection molding method of molding a desired shape at once is also known.

(Problems to be Solved by the Invention) However, in the above-described conventional welding method, it is necessary to shape three parts of the large diameter part a, the tapered part b, and the small diameter part c in advance, and these parts are Since they have to be joined one by one, there is a problem in that it takes time and labor to manufacture. Moreover, since the three parts are joined by welding, the total length of the different diameter pipe joint obtained is long, and it is difficult to connect with the pipe material during piping, and mechanical strength and dimensional accuracy There is also a problem that it is inferior, and the strength of the welded part is inferior, and if it is applied from the outside of the FRP for reinforcement, the weight increases and the manufacturing cost becomes high.

On the other hand, the injection molding method does not have the above-mentioned problems that the welding method has, but the cost of the mold required for molding is high, and the different diameter pipe joints are generally produced in a large variety of products in small quantities. For external products, this tendency is strong, and there is a problem that the manufacturing cost per unit becomes extremely high.

The present invention has been made for the purpose of solving the above-mentioned drawbacks and providing a method for manufacturing a different diameter pipe joint in which a lightweight and excellent strength product can be easily and inexpensively manufactured.

(Means for Solving the Problem) The gist of the present invention is to heat and soften the end portion of the pipe body to shape the large-diameter portion of the pipe joint and the tapered portion formed of the funnel-shaped inclined surface. After being forcibly inserted into the first outer mold having a mold surface, the tube is taken out and the end portion thereof is reheated (or not reheated) to have a shape substantially similar to the outer surface shape of the pipe joint. A different feature characterized in that it is inserted into a second outer die having the same inner surface shape, and then an inner die having an outer surface shape substantially the same as the inner surface shape of the pipe joint is forcibly inserted into the pipe body. It exists in the manufacturing method of the pipe joint.

In the production method of the present invention, as a means for heating and softening the end of the tube, for example, glycerin is used as a heating medium, and the end of the tube is immersed in a heating tank filled with this heated glycerin for a certain period of time. It is better to heat.

In the manufacturing method of the present invention, it is preferable that the taper portion formed of the first outer mold funnel-shaped inclined surface has an inclination angle of 10 to 20 degrees, and more preferably 13 to 20 degrees. This tilt angle
If it is less than 10 degrees, the total length of the pipe joint becomes longer than necessary,
If it is more than 20 degrees, the softened portion tends to buckle during molding.

In the manufacturing method of the present invention, the operation of forcibly inserting the tubular body into the first outer die or inserting the tubular body into the second outer die and then inserting the inner die For example, as shown in FIGS. 1 to 3, it may be performed in a state in which the large-diameter portion forming die surface of the forming die is erected on the plate body 5 in an upright state.

In the manufacturing method of the present invention, when the end portion of the heated tube body is inserted into the first outer mold until the tip end abuts against the upper surface of the plate body, the reduced tip end portion has an annular shape. Instead, a part may be recessed inward in the radial direction and have a wavy shape.

In the manufacturing method of the present invention, first, the large diameter portion and the tapered portion of the pipe joint are shaped by the first outer die, and then the small diameter portion is shaped by the second outer die and the inner die. Is the standard method, but first
With the outer mold, the large diameter part and the tapered part are preformed to a size smaller than the desired size of the pipe joint, and the next step, that is, the pipe having the inner surface shape substantially the same as the outer surface shape of the pipe joint When the inner mold having the outer surface shape substantially the same as the inner surface shape of the pipe joint is inserted into the outer tube of the pipe and then the tip of the taper portion whose diameter is once reduced to the funnel shape is moved outward. In addition to expanding to form a small diameter portion, the tubular portion on the front side, that is, the large diameter portion or the tapered portion may be expanded from the original shape and shaped to the final size.
By doing this, for example, the ratio of the large diameter portion and the small diameter portion is 2: 1.
It can be done to a certain degree.

(Operation) In the manufacturing method of the present invention, a mold surface capable of shaping the large diameter portion of the pipe joint and the taper portion formed by the funnel-shaped inclined surface is formed by heating and softening the end portion of the pipe body. Since it is forcibly inserted into the first outer mold, the end of the tubular body fits into the inner wall surface of the first outer mold while rubbing against it, and the softened portion follows the inner surface shape of the first outer mold. Thus, the large diameter portion and the tapered portion are shaped by being deformed and reduced in diameter.

Next, the tubular body shaped as described above is taken out and loaded into a second outer mold having an inner surface shape substantially the same as the outer surface shape of the pipe joint, and then the pipe body Since the inner die having an outer surface shape substantially the same as the inner surface shape is forcibly inserted and fitted, the most reduced diameter tip portion is smoothly expanded to form a small diameter portion, and not only the small diameter portion, Both the large diameter part and the tapered part are precisely finished to the desired size and shape.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

1 to 3 are sectional views showing an embodiment of the present invention divided into its molding steps.

Reference numeral 1 denotes a taper molding surface 12 having a cylindrical large diameter molding surface 11 having an inner diameter of 222 mm and a funnel-shaped inclined surface having a tilt angle of 13 degrees at its lower end.
1 is a first outer die having a diameter of 147 mm at the lower end of a taper portion molding die surface 22 formed of a funnel-shaped inclined surface having the same inclination angle as the large diameter portion molding die surface 21 having the same diameter as the outer die 1. Small-diameter molding surface 2
A second outer mold 3 having an inner surface shape that is substantially the same as the outer surface shape of the pipe joint consisting of 3, and 3 has the same shape as the second outer mold 2, but at the corresponding portions 31, 32, 33, respectively. It is an inner mold that has a small diameter of 22 mm and an outer surface shape that is almost the same as the inner surface shape of the pipe joint. In addition, 5 is the upper surface of the plate body on which these molds are placed.

Next, in order to carry out the manufacturing method of the present invention using the three types of molds, first, the tip of the heated rigid polyvinyl chloride pipe body 4 having a diameter of 200 mm is placed inside the first outer mold 1. As shown in FIG. 1, the taper portion 41 is formed by forcibly inserting it into the upper surface 5 of the plate until it abuts against it. As shown in FIG. 4, the cross-sectional shape of the tip portion of the taper portion 41 has a wavy shape in which a part is recessed inward in the radial direction.

Next, the tubular body 4 is taken out from the first outer mold 1 and loaded inside the second outer mold 2 to obtain the state shown in FIG. Further subsequently, the inner mold 3 is forcibly inserted into the inside of the tube body 4, and the tip end of the taper portion 41 is expanded outward as shown in FIG.
By forming the small diameter portion 42 and also finishing the inner surface of the pipe body 4, the different diameter pipe joint is completed together with the large diameter portion 43.

(Effects of the Invention) Since the method for manufacturing the different diameter pipe joint of the present invention is configured as described above, an integrated configuration can be obtained from one pipe body, and the conventional welding method can be used. In comparison, the labor and time required for processing can be significantly reduced, and the length of the pipe joint does not become longer than necessary, and a pipe joint convenient for pipe connection work can be obtained. Also, large diameter part, taper part,
Since each part of the small diameter part is integrally molded, it is possible to obtain a part having excellent mechanical strength. In addition, since the inner and outer molds are used, a product with excellent dimensional accuracy can be obtained, and since the shaping of the taper portion and the small diameter portion is performed in separate steps, it is easy to expand the diameter of the small diameter portion. It is also possible to obtain a material having a large reduction ratio between the small diameter portion and the small diameter portion, so that the application range is expanded.

[Brief description of drawings]

1 to 3 are cross-sectional views showing an embodiment of the present invention divided into molding steps thereof, and FIG. 1 is a view showing a state in which a tubular body is inserted into a first outer mold, FIG. 2 is a view showing a state in which the tubular body is taken out from the first outer die and loaded in the second outer die, and FIG. 3 is a view showing a state in which the inner die is further inserted and fitted in the same, FIG.
1 is a cross-sectional view showing the cross-sectional shape of the tip of the taper portion in FIG. 1, and FIGS. 5 and 6 are half cross-sectional views showing a welding method of the prior art. 1 ... First outer mold, 2 ... Second outer mold, 3 ... Inner mold, 4 ... Tube body, 11, 21, 31 ... Large diameter part molding die surface, 12, 22, 32 ... … Tapered molding surface, 23, 33 …… Small diameter molding surface, 41 …… Tapered portion, 42 …… Small diameter portion, 43 …… Large diameter portion.

Claims (1)

[Claims] Claim: What is claimed is: 1. A first outer mold having a mold surface capable of shaping the large diameter part of the pipe joint and the tapered part having a funnel-shaped inclined surface by heating and softening the end part of the pipe body. After forcibly inserting into
The tube is removed and its end is reheated (or not reheated) and loaded into a second outer mold having an inner surface profile substantially the same as the outer surface profile of the pipe fitting, and then A method for manufacturing a different-diameter pipe joint, characterized in that an inner die having an outer surface shape substantially the same as the inner surface shape of the pipe joint is forcibly inserted into the pipe body.