JPS5890927A - Manufacture of closed hollow body - Google Patents

Abstract

PURPOSE:To manufacture a closed hollow body simply by a method wherein a parison with the bottom thereof closed is arranged between dies as separately opposed to each other and closed grasped with a peripheral projection so that it is formed into a cavity with a higher internal pressure as the dies are clamped. CONSTITUTION:A thermoplastic resin is fed hanging between dies 1a and 1b as separately opposed to each other from an extrusion dies 2 as a parison 3. Then, when the dies 1a and 1b begins to be clamped, the bottom of the parison 3 is closed. The parison 3 is preblown with air blown in from a hole formed in the extrusion die 2. As the dies are clamped, peripheral projections 5a and 5b are inserted into the dies so that the parison 3 is pressed in contact with die cavities 4a and 4b and molded along the cavities 4a and 4b with the pressure therein 3 going up above 1atom. Then, the molding is cooled to harden and the dies are opened. After the removal of excessive flash, a closed hollow body is obtained with the internal pressure exceeding 1atom. It is used for floats, buoys, packing cushions and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a closed hollow body such as a float that can determine the position of a liquid level or a buoy that can determine the position of a fishing net when it is set in the sea.

Conventionally, this type of sealed hollow body was made by placing extruded barisun between molds, blowing compressed air through a blow needle inserted into the parison, blow molding, and then closing the blow hole penetrated by the blow needle. It was being processed. As for this secondary processing, there are methods of closing the hole by melting the resin into the m-target, or by pouring molten resin that can be bonded to the resin of the hollow body molded into this hole. Ta. However, this type of secondary processing has poor work stability, poor finished appearance, and requires multiple manufacturing steps when exact dimensions are required, making it complicated. . Furthermore, using conventional methods, it has been difficult to manufacture a sealed hollow body with an internal pressure of 1 atmosphere or more.

゛ The manufacturing method of the present invention was created in view of this point, and its purpose is to eliminate the need for many processing rods to produce a closed hollow body. The purpose of this invention is to obtain a sealed hollow body in which the temperature is increased to one package or more.

Embodiments of the present invention will be described below with reference to page 1.

1a and 'Ib are split-type molds that are spaced apart from each other, and the molds 1a and ib have an interval that is at least large enough to prevent the burrs 3 extruded from the extrusion die 2 from coming into contact with the burrs 3 when the burrs 3 is fed downwardly. It is arranged as follows.

Further, 4, +, and 4b are cavities in the mold formed to correspond to the shape of the desired sealed hollow body. 5a.

5b is a peripheral protrusion that slides in the mold clamping direction, and the peripheral protrusions 5a, 5b are configured to surround the cavities 4a, 4b. In addition, in the willow portions of the peripheral protrusions 5a and 5h, the molds ja and jh protrude from the mold parting surface in an open state, and the mold 1a.

The springs (i a + (i
denotes a burr pinch portion that slides in the mold clamping direction, and the burr pinch portions 7a and 7h have a width sufficient to sufficiently pinch the lower part of the burr head 3. In addition, the pinch parts 7a and 7b
A spring 6a is inserted into the peripheral protrusions 5a and 5b.
, (with a mechanism similar to ib, springs aa, ablJ''-
It is inserted. In addition, when the molds 1a and 1b are open, the peripheral protrusions 5a and 5b are spaced apart from each other so that they do not come into contact with the ballisson 3 when it is supplied hanging down, and the pinch parts 7a and 7b are connected to the peripheral protrusion 5a. , 5b, the spacing is narrower by at least the outer diameter distance dimension of the burr head 3.

The present invention will be explained below according to the manufacturing process. Thermoplastic plastics such as polyethylene, polypropylene, polyamide, vinyl chloride, etc. are melt-kneaded in an extruder (not shown), and the extrusion die 2 produces a plasticized tubular varnish 3.
Extruded as

Then, the extruded barisno 3 is placed in a mold 1a which is spaced apart from each other.
, 1b. Next, mold clamping of mold ja, 1h is started. As the mold clamping progresses, the pre-pinch portion 7a
, 7h come into contact with the balustrade 3, and as shown in FIG. Gas such as air is blown into the Parimen 13 through a closed and clamped blowing hole (not shown) at the bottom of the Parimen 3, and the Varisno 3 is pre-blown.

Next, as the mold clamping progresses, the peripheral protrusions 5a and 5b come into contact with the upper and lower parts or the entire circumferential surface of the barino 3, and the barino 3 protrudes around the mold cavities 4a and 4b as shown in Fig. 2. The peripheral protrusions 5a, 51)K are clamped, and the burr head 3 is sealed. By further proceeding with mold clamping, the peripheral protrusion 5a.

5b is inserted into the mold, the mold cavity 3 contacts and presses the mold cavities 4a and 4b, and the pressure inside the mold cavity 3 is increased to 1 atm or more as the mold clamping progresses. As shown in the figure, the barisno 3 is formed along the cavities 4a, 4b by the increased pressure within the parymen 3,
Mold clamping is completed. Next, the molded product that was molded along the cavities 4a and 4b and maintained an internal pressure of 1 atm or more was cooled and solidified, and then the molds 1a and 1b were opened (and as the molds opened, the molded product was inserted into the mold. Peripheral protrusion 5a,
5b and the pre-pinch parts 7a and 7b are folding springs $
The repulsive forces of a, 13b and 8a, 8b cause the molded product to protrude from the mold parting surface and move into the cavity 4a.

After taking it out at a distance of 4 hours, excess paris is removed to obtain a sealed hollow body having an internal pressure of 1 atmosphere or more.

In the above embodiment, the pre-blow of the burr member 3 has a smaller inner volume of the mold cavities 4a, 4h closed than the inner volume of the burr member 3 sealed by the peripheral protrusions 5a, 5b, and the pressure inside the burr member 3 is smaller. It is not necessarily necessary if the pressure can be increased to 1 atm or more as mold clamping progresses. In addition to using the pre-pinch portions 7a and 7b in the mold 3 as a means for closing the lower part of the burr head 3, other known means may be used to form the burr head 3 into a bottomed shape. Furthermore, the sliding mechanism of the pre-pinch parts 7a, 7b with the peripheral protrusions 5a, 5bf can be constructed simply and inexpensively by using the repulsive force of a spring, but in other cases, the sliding mechanism can be constructed by using pneumatic pressure or hydraulic pressure. It can also be configured.

The closed hollow body obtained by the manufacturing method of the present invention is a float,
These include marine buoys, cushioning bodies for packaging, hollow balls for heat and insulation that float on the liquid surface of industrial liquid tanks, and other vessels and containers. Further, the structure of the sealed hollow body is not limited in any way, and can be configured to suit the purpose. For example, when manufacturing a shock absorber for equipment consisting of a plurality of hermetically sealed hollow members connected together by one or more hinges, the ballisne pressure Ji that protrudes into the mold cavity is
It is also possible to provide a part a, and compress and thin the part corresponding to the hinge part of the ballison using the compressed part to form a bendable hinge part and mold it along the cavity shape to integrally mold the sealed hollow member. can.

As described above, according to the manufacturing method of the present invention, it is possible to easily manufacture a sealed hollow body without requiring a large number of processing culms as in the conventional method, and it is possible to easily manufacture a sealed hollow body with an internal pressure increased to one pressure or more. Hollow bodies can be obtained. In addition, since the peripheral protrusion is slidable, when the molded product is taken out of the mold, the peripheral protrusion protrudes and allows easy release from the mold, which is particularly effective for releasing resins that tend to adhere to metals. In addition, by using the sliding mechanism of the peripheral protrusion, the timing of mold release can be freely selected.
For example, an automatic take-out device can be installed in the process of taking out the molded product. Furthermore, according to the present invention, since a blowing needle is not used when molding the ballison into a cavity shape, it is possible to omit the blowing process, which is the most likely cause of defects in conventional blow molding, resulting in stable molding. play.

[Brief explanation of drawings]

1191, FIG. 2, and FIG. 3 are diagrams showing the steps of an embodiment of the present invention. la, lb...mold, 2...extrusion die, 3...parison, 4a, 4b...cavity, 5a, 5b...
・Peripheral protrusion, 6a, 6b...Spring, 7a, 7
b... Pre-pinch part for lower pinch of Balisun, 8a, 8
b... Spring patent applicant Hiroyoshi Nagase, representative of Kyoraku Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] The mold is clamped with the barisnow with its lower part closed between opposing molds, and the barisnow is clamped by the peripheral protrusion protruding around the mold cavity. As it progresses, the peripheral protrusion fits into the mold, bringing the ballisson into contact with the mold cavity, increasing the pressure inside the ballisne to 1 atm or more, and molding the ballisson into the cavity shape by the pressure. A method for manufacturing a sealed hollow body.