JPS5810212B2 - Seizou Hohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a relatively large tank such as a toilet tank, water tank, or tank for chemical solutions using a thermoplastic resin.

In the case of relatively small containers such as soy sauce, it is easier to maintain a certain shape even when the resin material is heated to near its melting point, so use a resin that has a relatively wide molding temperature range, such as polyethylene. It is blow molded using
When it comes to relatively large items such as toilet tanks, water tanks, or chemical tanks, even if you try to blow mold them using a material that has a relatively wide molding temperature range, it will be difficult to blow mold them due to their large size. , it cannot be molded by conventional blow molding methods because when the material is heated close to its melting point, it no longer holds a constant shape.

Therefore, in the case of such a large tank, the resin is heated to a temperature range from the softening point to the pour point, and then blow molded (referred to as cold blowing).

Furthermore, in the case of resins that have a narrow molding temperature range, such as vinyl chloride resin, during the time required for molding large-sized products,
It is also technically extremely difficult to maintain it at a high temperature close to the pour point.

Therefore, in the conventional method, when molding a large tank using a thermoplastic resin or when blow molding a tank using a thermoplastic resin with a narrow molding temperature range, it is necessary to Cold blow molding was performed by heating to a temperature range of For example, from a place where the end cannot be closed,
As already known in No. 43, in the conventional method, both ends of a resin tube are once sealed and inflated into the desired shape, and then the seals are removed and the open end on the bottom side is sealed. The closure was then reattached using adhesive.

However, such a method requires extra man-hours, such as having to remove the seal plug sealing the open end of the resin tube after inflating it, and then fitting the sealing tool.

Therefore, the present inventor first proposed a method for manufacturing a tank using thermoplastic resin without using such an inconvenient method, by heating a thermoplastic resin pipe to a temperature range above the softening point and below the pour point. One open end of this resin tube was closed by squeezing it with a split mold for pinching, and the other open end was sealed with a seal to airtightly seal the openings at both ends. blowing high-pressure fluid through the seal plug;
It is made of thermoplastic resin, characterized in that it is bulge-molded into a desired shape, and the end of the tube to be pinched and closed by the split mold is bonded with an adhesive or heat welding means during or after the pinching. Developed a method for manufacturing tanks.

According to such a method, unlike a conventional tank manufacturing method using a cold blow molding method in which a thermoplastic resin pipe is heated to a temperature above the softening point and below the pour point,
This type of plastic resin tank does not require the trouble of removing the temporary frame after expansion molding the open tank bottom and then gluing a sealing device to it. This manufacturing method is not without its drawbacks; in this method, when the pipe end of the resin pipe is pinched and closed using a split mold for pinching, since the other pipe end is circular, the pinching pressure is reduced. As shown in Fig. 8, the edge a of the tube end of the tube is curved in the direction in which the pinching distance gradually decreases as it approaches the center of the tube, so give it a sufficiently thick pinching margin. Otherwise, there is a problem that it is difficult to securely pinch and close the tube end, and depending on the pinching operation of the split mold for pinching, the length of the end edge a of the tube end of the pinching part may be There was a drawback that there was a risk that the pattern would be uneven.

This invention improves these points as well, and its gist is to heat a thermoplastic resin pipe to a temperature range above the softening point and below the pour point, and to open one opening of the resin pipe. The end is once crushed into an oval shape, and both ends in the longitudinal direction are held by being pinched by split molds for clamping, and then moved in a direction to bring the split molds for clamping pressure relatively closer together. By doing so, the open end is compressed and closed in a cross shape, and the other open end is sealed with a seal to airtightly seal the openings at both ends, and high-pressure fluid is passed through the seal into the pipe. is blown into a desired shape, and the cross-shaped clamping closure part is adhered in a sealed state during or after clamping using a filler, filling adhesive, or heat welding means. A method of manufacturing a thermoplastic resin tank is provided.

Next, the method for manufacturing a thermoplastic resin tank according to the method of the present invention will be described in more detail with reference to the drawings and examples. Examples of the thermoplastic resin pipe that can be used in the present invention include polyethylene, Polypropylene, polycarbonate.

There are pipes made of resins such as ABC resin, methacrylic resin, polystyrene, and polyvinyl chloride, but in the following examples, we will explain the case where vinyl chloride resin pipes are used.
d is one end of the hard vinyl chloride resin pipe 2 brought to the position shown by the chain line in FIGS. The clamping split mold 1a is fixedly installed at the position shown in the figure, and the clamping split molds 1b and 1d are respectively attached to the split molds 1b and 1d. The split mold 1c for clamping is provided so as to be movable forward and backward in the direction of the mold 1a (the horizontal and vertical directions in FIG. 2).
and 1d direction (up-down direction and left-right direction in FIG. 2) so that the clamping split molds 1a and
1b, 1c, and 1d, in the open state where these are kept in the positions shown in Figures 1 and 2, respectively, the vinyl chloride resin pipe 2 is brought to the position shown by the chain line, and the split molds 1b and 1c for clamping are first placed. When displaced to the left in the top of Figure 2, each split mold 1
With a, 1b and 1d, 1c, both longitudinal ends of the tube end 2a, which have been crushed into an oval shape as described above, can be compressed from the left and right sides, and then, while maintaining this state, the clamping When the split molds 1d and 1c are displaced in the direction of the split molds 1a and 1b (in the vertical direction in FIG. 2), the unsqueezed portion of the tube end 2a is temporarily moved in the horizontal direction in the top of FIG. 3, as shown in FIG. After expanding, the tube end 2a is compressed between the split molds 1a and 1d and between the molds 1b and 10, and finally the tube end 2a is compressed in a cross shape from all sides as shown in FIG. It has become.

Reference numeral 3 denotes a seal plug positioned so as to be able to fit into the other open end of the tube 2 brought to the position shown in FIG. for example, a compressed air supply source (not shown), and
is a split mold for blow molding to shape the tube 2 when it is blown up.

Next, the method of the present invention using such a molding device,
Describing the process step by step, in the method of the present invention, first, the molding molds 5 and 6 opened in the state shown in Figs. Then, a vinyl chloride resin pipe 2, which has been heated in advance to a temperature below its softening point and above pouring point using an appropriate heating device, is pressed into an oval shape by any means with one pipe end 2a, and the pipe is An adhesive is applied to the inner circumferential surface of the end 2a, and the tube end 2a is crushed into an oval shape.Both ends in the longitudinal direction of the tube end 2a, that is, when the length of the outer circumference of the tube is l, are 1/1/2 of each end. A portion corresponding to the length of 41 is split into clamping molds 1a, 1b, and 41 which are opened as shown in Figs.
Of the split molds 1c and 1d, the split molds 1b and 1c are displaced to the left in FIG.
By displacing the tube end 2a in the direction b (vertical direction in FIG. 2), the remaining central portion of the tube end 2a is compressed so as to be crushed from the front and back directions, and the inner circumferential surface of the tube end 2a is
The radial direction of the cross shape is sealed with adhesive in an airtight manner.

Next, the seal plug 3 is inserted into the other open end, and then the molding molds 5 and 6 are closed, and the outer surface of the vinyl chloride resin pipe 2 is positioned within the molding molds 5 and 6. Blow hole 4
Compressed air is blown into the tube 2.

In this way, the vinyl chloride resin pipe 2 blown with compressed air expands and is shaped to match the inner surface shape of the molding molds 5 and 6.

Next, the supply of compressed air is stopped, the seal plug 3 is removed from the tube end, and cooling air is blown into the tube 2 to cool the shaped vinyl chloride resin tube 2. When the pressing split molds 1b, 1C, and 1d are returned to their original states (FIGS. 1 and 2), a product 2' as shown in FIG. 6 is obtained.

In the above embodiment, adhesive is applied to the inner circumferential surface of the tube end 2a of the vinyl chloride resin pipe 2 which has been softened by heating, and the core portion is then pinched, thereby reducing the pinching pressure and the pressure at the time of squeezing. At the same time, an example has been shown in which the tube end 2a is glued in a closed state, but in other embodiments, the tube end is pinched with the split mold for pinching without using such an adhesive, and then Welding only the part to be compressed by partial heat welding means such as heat welding means using ultrasonic waves, for example,
Alternatively, the core may be adhered in a closed state by later filling the gap between the pressed and closed portions with a filler adhesive.

In addition, in the above embodiment, the clamping split molds 1a, 1b, 1
Among c and 1d, the other split mold 1b is placed in the direction of the fixed mold 1a.
・Although an example has been shown in which the tube end 2a is pinched and closed by relatively displacing the pipes 1c and 1d, in other embodiments, as shown in FIG. 1'a・1
'b, 1'c and 1'd are configured to be openable and closable, respectively, and both ends of the tube end 2a crushed into an oval shape are formed into split molds 1'a and 1'd.
1'b, 1'c, 1'd are pinched by rotating them respectively, and then the split molds 1'a, 1'b and 1'c, 1
Even if the central part of the tube end 2a is also pinched from the left and right by displacing 'd relatively toward the center, the tube end 2a is similarly pinched in an airtight state in the cross-shaped radial direction and closed with adhesive. It is a vine.

Above, the method for manufacturing a thermoplastic resin tank according to the present invention has been explained with reference to Examples, but in the method of the present invention,
The resin tube that has been heated and softened as described above is sealed only at one end, which will be the opening of the product, and the open end, which will be the bottom of the product, is closed with pressure to make the inside of the tube airtight. None, because this is blown up, unlike the conventional tank manufacturing method using cold blow molding, which involves heating a thermoplastic resin pipe to a temperature above its softening point and below its pour point, it is formed into an open state. Needless to say, the present invention does not require the trouble of removing the temporary frame and gluing the sealant to the tank bottom after expansion and shaping. By crushing the tube end into an oval shape in advance, first compressing both ends in the longitudinal direction, and then displacing both ends toward the center in that state, the tube end is Since the center part is pinched and the pipe ends are pinched and closed in a cross shape, when the pipe is pinched, there is no escape like the example shown in Figure 8, which is small. With the pinching allowance, it is possible to give a uniform pinching allowance to the bottom of the tank, and the length of the part pressed in a cross shape is not uneven, and it can be pinched in a good appearance. It is something that

Furthermore, according to the method of the present invention, it is of course possible to obtain a tank at a lower cost with fewer man-hours.

[Brief explanation of the drawing]

Figures 1-5 show an embodiment of the method for manufacturing a tank made of thermoplastic resin according to the present invention, and Figure 1 is a front view of the split mold for clamping and the split mold for molding opened; Fig. 2 is a cross-sectional plan view of the same (the cross section is taken along the line ■-U in Fig. 1), Fig. 3 is a cross-sectional plan view of the clamping split mold partially closed from the state shown in Fig. 2, and Fig. 4 is A vertical sectional front view of the thermoplastic resin tube placed in the bislit mold and closed (the cross section is taken along line IV-IV in Figure 5), Figure 5 is a bottom view of the same, and Figure 6 is the product. front view of,
FIG. 7 is a cross-sectional plan view similar to FIG. 2 showing another embodiment, and FIG. 8 is a perspective view of a tank bottom formed by another method. 1a, 1b, 1C, 1d, 1'a, 1'b, 1'c, 1
'd...Split mold for squeezing, 2...Thermoplastic resin pipe, 3...Seal plug, 5, 6...Split mold for molding.

Claims (1)

[Claims] 1 A thermoplastic resin pipe is heated to a temperature range from the softening point to the pour point, and one open end of the resin pipe is crushed into an oval shape, and then both longitudinal ends are pinched. The opening end is clamped and held in a cross-shaped manner by pressing and holding it with the pressing split mold, and then moving the pressing split mold in a direction that brings it closer to each other. After sealing the openings at both ends airtightly, a high-pressure fluid is blown into the tube through the seals to expand it into a desired shape, and the cross-shaped clamping closure is performed. by adhesive or filling adhesive or heat welding means,
A method for manufacturing a thermoplastic resin tank, characterized by adhering the tank in a sealed state during or after pressing.