JPS60199632A - Manufacture of flanged tube body by blow molding - Google Patents

Abstract

PURPOSE:To improve the quality of a poduct by adding a process of inserting a support means functioning as insert into the tube body to the production process of a flange integral with the tube body to uniformize the thickness of the tube body portion where the insert is put. CONSTITUTION:A short tube P made of a hard vinylchloride is mounted and a hot fluid is fed to a nozzle hole 8 of a mobile insert 6 at a very low pressure to soften the short tube P. The mobile insert 6 is moved and stopped at the position of an inner die 4. Then, a mobile mount plate 2 is brought close to the inner die 4 and a hot fluid is fed to the nozzle 8 at a low pressure (3-4kg/cm<2>) to bulge the short tube P radially. After the mobile mount plate 2 further approaches it, the supply of the hot fluid is stopped and the bulged portion is bent in two closely. Finally, the short tube P is taken out of the inner die 4 and a clamp part 16 is cut off to obtain a flanged tube joint.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a flanged pipe body by blow molding, and more particularly to a method for manufacturing a flanged pipe joint.

Conventionally, hard vinyl chloride pipe fittings for general water supply and the like are mainly made of vinyl chloride polymer and are manufactured by injection molding or extrusion molding. As for the types of joints, sockets, bends, S-bends, and collars are standardized as water pipe joints, and other pipe joints comply with the standards for iron flanged joints. Therefore, for example, flanged pipe joints made of hard vinyl chloride manufactured according to such standards are sufficiently guaranteed in quality such as strength.
On the other hand, when used as a flanged pipe joint for a low-pressure waterway, for example, an overflow pipe of a water storage tank, the product is of excessive quality and is therefore expensive.

Furthermore, flanged joints manufactured by injection molding require high equipment costs for the molding machine and mold, resulting in high product prices.

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,
Blow molding uses inexpensive molds made of cast iron or light alloy castings because the molding equipment is not very expensive, the working temperature is 150℃ or less, and the pressure used is 10kg/- or less. As a result, the product price can be kept relatively low. Therefore, a method of manufacturing a synthetic resin saddle joint using a so-called two-stage blow molding method has been proposed, which takes advantage of these advantages. In this manufacturing method, a cavity for forming the socket and flange of a flanged pipe joint is formed in a split mold for joint forming, a nozzle is provided at each end of the split mold, and a cavity is formed in each of the two nozzles. After fitting the straddling short tube and softening the short tube by introducing heating fluid through a nozzle, the internal pressure of the heating fluid is further increased to approximately 8 kg/cJ.
The short tube is bulged out to a greater extent to conform to the shape of the cavity, and one nozzle is moved closer to form a brim-shaped saddle.

In the case of such a manufacturing method, as mentioned above (the internal pressure of the heated fluid is relatively high, about 8 kg/d or more, when fixing the short tube to the nozzle, it is not only necessary to firmly fix it, but also to swell the short tube). When doing so, there was a risk that uneven thickness would occur because there was no means to uniformly control the pipe wall thickness at the socket portion of the molded joint.

Therefore, the present invention was created in an attempt to eliminate the inconveniences in the conventional blow molding method for manufacturing a flange body provided on a pipe body.Hereinafter, the present invention will be explained in detail based on the equipment used in the method of the present invention. do.

1 to 2 are cross-sectional views at each molding process. 1 is a cylindrical outer mold, which can be divided into two parts in the vertical direction in FIG. 1 at its center. Reference numeral 2 denotes a movable mounting plate having a razor blade 3 recessed in its inner surface, and is adapted to slide in the left-right direction in FIG. 1 within the cylindrical outer mold 1.

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 21u11 of the inner mold 4 in a protruding manner. Reference numeral 6 denotes a movable core, which slides from side to side 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 core 6 and opens toward the movable mounting plate 2. A small diameter portion 10 is provided on 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 inclined surface of about 45° 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 is the socket part of the flanged joint A, 14
indicates a flange, and 15 indicates a bolt hole.

In this embodiment, in the above-described blow molding machine, a short pipe P made of hard vinyl chloride, which has been cut to a predetermined length and a predetermined diameter, is removed from the outer mold 1 with the movable mounting plate 2. Then, it is inserted into the movable core 6 and installed.

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 outer mold l,
Complete preparation (built-in process). This is shown in ■ in Figure 1.

Next, heating fluid is supplied to the nozzle hole 8 of the moving core 6 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 movable core 6 moves, the tower of the short tube P slightly expands, and the movable core 6 is inserted into the short tube P (insertion stroke). This is shown in Figure 1 (■).

Next, move the movable mounting plate 2 toward the inner mold 4 as shown by the arrow in the figure, and apply a low pressure (3 to 4 kg/c) to the nozzle 8.
j) Supply the heating fluid of A). As a result, the short tube P expands in the radial direction and contracts in the axial direction between the movable mounting plate 2 and the inner mold 4 (expansion stroke).

This is shown in ■ and ■ in FIG.

Furthermore, when the movable mounting plate 2 is brought closer to each other and the supply of heating fluid is stopped, the short tubes at the bulging portions are bent in two and brought into close contact with each other. Here, the protrusion 5 provided on the inner mold 4 allows for closer contact locally (
close contact process). Later, bolt holes for the pipe joint will be cut in this localized area.

Finally, when the movable mounting plate 2 and movable core 6 are removed from the outer mold 1, the formed short tube P remains in the inner mold 4, and if the outer mold 1 is further divided, it will become as shown in Figure 1 ■. , the inner mold 4 and the molded short tube P can be taken out. Here, since the protrusion 5 and the notch 11 form an undercut, the protrusion 5 is retracted by an appropriate means and the short tube P is taken out from the inner mold 4. This is shown by ■ in FIG. Also, by cutting off the clamp portion 16 inserted into the razor blade 3, a flanged pipe joint as shown in Fig. 2 can be manufactured.

The above explanation describes the method for manufacturing a flanged pipe joint, but the method for manufacturing a flanged pipe body by the blow molding method of the present invention may also be used for the manufacturing method for a pipe joint with a skirt portion. If the product has a flange integrated into the pipe,
In addition, in the built-in process, the insertion process, the expansion process, and the 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. .

In summary, the present invention includes a step of incorporating a short tube so as to support at least both ends in a mold, and blowing pressurized fluid into the short tube from a nozzle hole provided in the support means to transform the short tube into a bulging short tube. In the method for manufacturing a flanged short tube, which includes a step of moving the support means closer to bring the bulging short tube into close contact with the short tube, the method includes adding a step of inserting at least one of the support means as a core into the short tube. This method of manufacturing a flanged tube body made of synthetic resin by blow molding is characterized by the following effects.

In other words, the step of inserting the support means that functions as a core into the tube body is added to the process of manufacturing the flange body that is integrated with the tube body by the blow molding method, so that the tube body with the core inserted is The wall thickness of the part is regulated by the acid core and becomes uniform, improving the quality of the molded product. In addition, since the acid core is inserted, the volume within the tube is reduced and the amount of insufflation fluid can be reduced, which in turn allows the use of low-pressure insufflation fluids, thereby reducing the volume of the tube and supporting members. The clamping state of the tube may be loose, making it easy to incorporate or remove the tube body, and as a result, productivity is improved.

[Brief explanation of the drawing]

■ to ■ in Figure 1 are cross-sectional views of each step in the embodiment of the present invention, Figure 2 (A) is a cross-sectional view of a flange-flange joint manufactured according to the embodiment of the present invention, and Figure 2 (B) is A front view of a half-illustration of the same joint is shown. 1... Outer mold, 2... Moving mounting plate, 6... Moving core, 8... Nozzle hole, P... Short managing agent Yoshihiko Okabe, Patent attorney, Figure 1, Figure 1 Figure 1

Claims (1)

[Claims] a step of incorporating a short tube so as to support at least both ends within the mold, and a step of blowing pressurized fluid into the short tube from a nozzle hole provided in the support means to make the short tube into a bulging short tube; In the method for manufacturing a flanged tube body, which comprises a step of moving the support means closer to bring the bulging short tube into close contact with the short tube, the method further includes adding a step of inserting at least one of the support means as a core into the short tube. Manufacturing method for synthetic resin flanged pipes using the characteristic blow molding method