JPS6216124A - Manufacutre of flanged pipe joint by blow molding - Google Patents

Abstract

PURPOSE:To enhance the quality of the socket part of a molded flanged pipe joint by a method wherein a supporting means to support a short tube is inserted in the tube body of the short tube as a core so as to result in making the thickness of the tube body part, into which the core is inserted, uniform. CONSTITUTION:Firstly, a short tube P is softened by supplying heating fluid under extremely low pressure through the nozzle hole 8 of a movable mounting plate 2 into the short tube P. Secondly, a movable core 6 is shifted in the direction indicated by the arrow and stopped when its end reaches an inner mold 4. Thirdly, the movable mounting plate 2 is made to approach the inner mold 4 and at the same time low pressure heating fluid is supplied to the nozzle hole 8. As a result, the short tube P swells radially while the axial distance between the movable mounting plate 2 and the inner mold 4 being gradually reduced. In addition, by stopping the supply of the heating fluid together with the approaching of the movable mounting plate 2 to the inner mold 4, the radially swollen short tube P is folded in two so as to form a flange by closely contacting with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improvement in the manufacturing method of a flanged pipe joint by blow molding.

[Conventional technology and its problems]

Conventionally, hard vinyl chloride flanged pipe fittings for general water use, etc., are mainly made of vinyl chloride polymer.
Manufactured by injection molding or extrusion method,
As for the types of joints, sockets, bends, S-bends, and collars are standardized as water pipe joints, and the standards for iron flanged joints are applied mutatis mutandis to other pipe joints. Therefore, flanged pipe fittings made of hard vinyl chloride manufactured according to these standards are sufficiently guaranteed in quality such as strength, and are instead used for low-pressure waterways, such as overflow pipes of water storage tanks. When used as a flanged pipe fitting, the product is of excessive quality and is therefore expensive.

In addition, especially for flanged pipe fittings manufactured by injection molding, the equipment costs required for the molding machine and mold are high, which also affects the product price.

On the other hand, an attempt has been made to manufacture such a flanged pipe joint by a blow molding method to provide an inexpensive product (Japanese Unexamined Patent Publication No. 117616/1983). That is,
According to this proposal, the molding equipment for blow molding is not very expensive, the working temperature is 150°C or less, and the pressure used is 10 kg/cd or less. Since a mold can be used, the product price is also relatively low. Therefore, a method for manufacturing a synthetic resin saddle joint using a so-called two-stage blow molding method has been introduced, which takes advantage of these advantages. In this manufacturing method by blow molding, a cavity for forming a socket blow and a flange blow of a flanged pipe joint is formed in a split mold for molding a joint, and nozzles are provided at both ends of the split mold. Fit the short tube across both nozzles and apply pressure from the nozzle! After introducing the fluid to soften the short tube, the internal pressure of the heated fluid is further increased to approximately 8 kg/cd.
The short tube is bulged out to a certain extent to conform to the shape of the cavity, and one nozzle is brought closer to the other nozzle to form a brim-like saddle.

However, in this manufacturing method, the internal pressure of the heated fluid is relatively high, about 8 kg/- or more, as described above, and when fixing the short tube to the nozzle, it is not only necessary to firmly fix it, but also to expand the short tube. When the pipe is drawn out, there is no means to uniformly control the pipe wall thickness at the socket portion of the molded joint, so there is a risk of uneven wall thickness.

In order to solve these inconveniences in the conventional blow molding method for manufacturing a flange body extending into a pipe body, the present inventors have attempted to remove the core that supports the short pipe to be formed using a heating pressurized fluid. After blowing into the short tube, a manufacturing method was created in which the tube was inserted into the short tube with a slight bulge.

However, in this manufacturing method, the short tube is bulged out in the radial direction in the middle, bent in half, and then tightly attached to each other to form a flange. In particular, if a large number of bolt insertion holes were drilled in the flange, the holes would communicate with the cough cavity in the finished product, and there was a risk that the fluid inside the pipe would leak from the cavity. .

[Means for solving problems]

Therefore, the present invention has been improved to further eliminate the disadvantages of the existing invention, and will be described in detail below based on equipment that uses the method of the present invention.

From ■ to ■ in FIG. 1 are cross-sectional views at each molding process in the equipment used in the present invention. 1 is a cylindrical outer mold, and the outer mold 1 is located on the center line of the It can be divided into two parts vertically. Reference numeral 2 designates a movable mounting plate having a recessed inner surface with a recess 3, the details of which are shown in FIG. It has become. Reference numeral 4 denotes a flat plate-shaped inner mold, which is fixed to approximately the center of the outer mold 1. A coin-shaped protrusion 5 is provided on the movable mounting plate 2 side of the inner mold 4 in a protruding manner. Reference numeral 6 denotes a movable core which is adapted to slide in the left-right direction in FIG. 1 within the cylindrical outer mold 1 using the outer periphery of its flange portion 7 as a sliding surface.

A nozzle hole 8 is bored in the movable mounting plate 2 and is open toward the movable core 6. A small diameter portion 10 extends from the inner end surface of the movable core 6 via a conical portion 9 having an inclination of approximately 45°. Further, a notch 11 having an approximately 45" slope is provided on the inner diameter surface of the inner mold 4, and the conical portion 9 and the notch 11 form a stopper 12 of the joint. 13 14 is a socket portion of a molded flanged pipe joint A, 14 is a flange, and 15 is a bolt hole.

Here, the details of the movable mounting plate 2 are shown in FIG. 2, and the movable mounting plate 2 has a support shaft 2
It is fixed to the tip of 0. The support shaft 20 is a base shaft 2
1. A piston shaft 22 that is screwed and directly connected to the base shaft 21;
It consists of a heated air joint shaft 23 screwed and connected to the piston 22, and a nozzle hole 8 is bored in these members 21, 22, 23.

The movable mounting plate 2 is fitted onto the tip of the base shaft 21, and a presser plate 25 is screwed so as to press and fix the movable number plate 2. Note that an annular groove is formed between the fitting hole 38 formed in the movable mounting plate 2 and the outer periphery of the holding plate 25, and the annular groove corresponds to the razor blade 3.

The piston shaft 22 has a piston portion 2 at its axial center.
A cylinder 27 is fitted into the piston part 26, and both end surfaces of the cylinder 27 are pressed by square flange parts 28 and 29. In other words, these flange parts 2
8.29 supports the cylinder 27 with a plurality of bolts 30. The bolts 30 pass through the flange portion 29 and are screwed into the base plate 35 via the collar 33. Therefore, the flange portion 28.29 , the collar 33 and the base plate 35 are integrated with bolts 30. A second pressurized air hole 31 is provided in one flange portion 28, and a first pressurized air hole 31 is provided in the other flange portion 29. Air holes 32 are bored.

The base plate 35 has as many rods 3 as there are bolt holes 15 in the flange 14 to the flanged pipe joint to be molded.
4 is protruded and retracted, and a needle 35 is provided at the tip of the cough rod body 34. The tip of the rod 34 slides within a sliding hole 36 formed in the transfer J mounting plate 2, and the needle 35 is configured to be freely retractable from the surface of the movable mounting plate 2.

A heated air pipe 37 communicating with the nozzle hole 8 is connected to the heated air joint shaft 23 .

In this embodiment, in the blow molding machine described above, the movable mounting plate 2 is removed from the cylindrical outer mold l, and a short pipe P made of hard vinyl chloride, which has been cut to a predetermined length, is moved. Insert it into the child 6 and attach it.

However, in this case, it may be connected to an extruder that molds the parison. Next, the movable mounting plate 2 is attached to the cylindrical outer mold 1 to complete preparations (built-in process).

This is shown in Figure 1 (■).

Next, heating fluid is supplied to the nozzle hole 8 of the movable mounting plate 2 at a very low pressure to soften the short pipe P.

Next, the movable core 6 is moved in the direction of the arrow as shown in FIG. 1, and stopped when its end reaches the inner mold 4. At this time, as the moving core 6 moves, the diameter of the short tube P expands slightly, and the moving core 6 is inserted into the short tube P (insertion stroke). This is shown in Figure 1 (■).

Next, attach the movable mounting plate 2 to the inner mold 4 as shown by the arrow in Figure 1.
At the same time, low pressure (3 to 4
kg/cII of heating fluid is supplied.

As a result, the short pipe P expands in the radial direction and gradually reduces the distance in the axial direction between the movable attachment Fi2 and the inner mold 4 (expansion stroke). This is shown in ■ and ■ in FIG.

Furthermore, when the movable mounting plate 2 is moved closer to the inner mold 4 and the supply of heating fluid is stopped, the short pipes P are bulged in the radial direction and are bent in two and come into close contact with each other. At this time, the protrusions 5 provided on the inner mold 4 cause closer contact locally (adhesion process). Later, a bolt hole for a pipe joint will be drilled in this local contact area.

Here, to explain the operation of the movable mounting plate 2 in detail, in FIG. When pressurized air is supplied to the air hole 32, since the movable mounting plate 2 and the support shaft 20 are in a stationary state, the cylinder 27 moves to the right in FIG. do. Since the cylinder 27 is integrated with the base plate 35 on which the rod 34 is attached, the needle 35 moves forward and to the right as shown by the two-dot chain line in the figure).
is bulged out in the radial direction of the short pipe P and rushes into the closely contacted part. Next, when pressurized air is supplied to the second pressurized air hole 31, the cylinder 27 moves to the left in the figure.
The needle 35 moves backward and leaves. At this time, the air and gas remaining in the joint that bulges out in the radial direction and is in close contact with each other (adhesive is applied to the joint, and the gas caused by the adhesive) is blown out. , eliminate the cavity.

Finally, when the movable mounting plate 2 and the movable core 6 are removed from the outer mold 1, the molded flanged pipe fitting A is removed from the inner mold 4.
By further dividing the cylindrical outer mold l, the inner mold 4 and the molded flanged pipe fitting A can be taken out, as shown in FIG.

Here, since the projection 5 and the notch 11 form an undercut, the projection 5 is retracted by an appropriate means and the flanged pipe joint A is taken out from the inner mold 4. Next, by cutting off the clamp portion 16 inserted into the scissors 3, the flanged pipe joint A can be formed.

In addition, in the built-in process, insertion process, expansion process, and close contact process in the present invention, for example, the insertion process may be performed simultaneously with the expansion process, and the order of these processes is not particularly limited.

〔Effect of the invention〕

In summary, since the present invention employs the structure described in the claims, the following effects are achieved.

In the process of forming the flange, which is integrated with the tube by blow molding, we added the step of inserting the support means for supporting the short tube as a core into the tube, so the portion of the tube into which the core is inserted is The wall thickness is regulated by the core and becomes uniform,
The quality of the socket part of the molded flanged pipe joint is improved. In addition, since the cough core is inserted, the volume inside the tube is reduced and the amount of blow fluid used is small, so the tube and support member only need to be clamped loosely, making it easier to hold the tube. It becomes easier to incorporate or remove the device, and as a result, productivity is improved.

Moreover, by inserting and removing the needle into the part corresponding to the bolt hole for the flange of the tightly fitted part, a cavity will not be created in the tightly fitted part of the flange of the pipe joint to be formed, and of course, the bolt hole will be removed. Because the needle is drilled, no needle hole remains.

[Brief explanation of the drawing]

1 to 2 are sectional views of each step in the implementation of the present invention, and FIG. 2 is a partially sectional side view of an apparatus using the present invention. DESCRIPTION OF SYMBOLS 1... Outer mold, 2... Moving mounting plate, 6... Moving core, 8... Nozzle hole, 35... Needle, P... Short tube.

Claims (2)

[Claims] (1) A step in which the short tube is built into the mold so that it supports at least both ends, and a pressurized fluid is blown into the short tube from a nozzle hole provided in the support means to radially move a part of the short tube. A method for manufacturing a flanged pipe joint comprising a step of bulging, and a step of bringing one of the support means supported at both ends close to the other to bring the bulged portion into close contact, wherein the bulged portion is A method for producing a flanged pipe joint made of synthetic resin by blow molding, which comprises adding a step of inserting and withdrawing a needle into a portion corresponding to a plurality of flange bolt holes of the closely-attached portion after the step of bringing the parts into close contact with each other. (2) A flanged pipe joint made by blow molding according to claim (1), which includes a step of inserting at least one of the supporting means as a core into a short pipe while slightly expanding the pipe. Manufacturing method.