JPH0367855B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a blow product with protrusions molded from a thermoplastic resin.

Generally, when there is compression along the parting line of a blown product or when protrusions are integrally molded, the width of the parison is required to extend to the protrusions, etc., and the closing of the mold is used to close the parison. The part is cut out, and a protrusion etc. is formed by the cut.

The disadvantages of this conventional method are that burrs are generated because the sides of the parison are cut off to form protrusions, and the parting line including the protrusions is cut off, resulting in large material loss. Finishing is required because the cut marks remain, and even if finishing is done well, it is difficult to completely remove the cut marks.

Particularly, in a blow molded product in which protrusions 2, 2 are integrally molded on both sides of a cylindrical hollow body 1 with a part of the hollow body 1 as shown in FIG. appears as if it were seam 3, which often impairs the appearance of the product.

This invention was devised in order to solve the above-mentioned conventional problems, and its purpose is to easily and reliably form protrusions on the side of a molded body, and to achieve the desired shape as shown in FIG. , hollow body 11
To provide a new method for producing a blow-molded product capable of obtaining a blow-molded product without cut marks on the side surface of a hollow body 11 even though projections 12, 12 are integrally molded with a part of the hollow body 11. It is in.

Furthermore, as long as the protrusions, etc. are located on the barting line of the blow-molded product, the protrusions, etc. can be molded with a part of the main body, regardless of the product shape. To provide a method for manufacturing a blown product with protrusions, which can have the same width as a parison when molding the product and has extremely little material loss.

A further object of the present invention is to provide a method for manufacturing a blow product with projections, in which the projections, etc. to be molded can be formed into hollow shapes, and, if necessary, required holes can be made in the projections, etc. during molding. .

A feature of the present invention for the above-mentioned purpose is a method for manufacturing a hollow molded product having a protrusion on the side surface, which comprises two pairs of split molds for forming the main body disposed above and below the protrusion, and a cutter protruding from the mold surface. A blow mold consisting of a protrusion split mold in which a notch corresponding to the protrusion is formed and which is sandwiched between the main body split molds so as to be openable and closable at right angles to the flow direction of the parison is used. The parison extruded or injected into a mold is temporarily blown with air by closing only the split mold for the main body, and the part of the parison located in the split mold for protrusions is bulged out between the split molds for protrusions by the air blow. The mold is closed, and the swollen part is flattened by the mold surface, and the extra length protruding from the notch is cut by the cutter to form a protrusion of the desired shape, and air blowing is performed. The objective is to complete the product.

This invention will be explained in more detail below with reference to embodiments shown in FIGS. 3 to 6.

In the figure, reference numeral 21 denotes a blow mold, and between two pairs of split molds 22, 22 for molding the main body of the hollow body 11 shown in FIG. 2, a pair of split molds 23, 23 for molding the projections 12, 12 on both sides. It consists of something that incorporates.

These protrusion split molds 23, 23 are the main body split mold 2.
2, 22 are connected to plungers 26, 26 of air or hydraulically actuated cylinders 25, 25 fixed to mounting plates 24, 24.
25, the upper and lower main body split molds 22, 22
As a guide, they slide at right angles to the flow direction of the parison in the blow mold, opening and closing each other.

Further, one mold closing surface of the protrusion split molds 23, 23 is formed flat, but the other mold closing surface has a cutter 27 that forms the outline of the protrusions 12, 12, as shown in FIG. , 27 and guide pins 28, 28 on the outside thereof protrude, and a notch corresponding to the protrusion 12 is formed by the cutter 27.

In this embodiment, the sliding movement of the protrusion split mold 23 is performed using the cylinder 25, but this sliding movement can also be performed using mechanical means such as a spring member. In such cases, the mold thickness can be made smaller than when using a cylinder device.

Further, in the case of drilling a hole in the protrusion 12, although not shown in the drawing, a drilling pin may be placed protrudingly in the notch.

Next, the manufacturing method of the present invention will be explained.

First, the main body split molds 22, 22 and the protrusion split molds 23,
23 is opened, the parison 29 is injected or extruded into the cavity of the blow mold 21 in the same manner as in normal blow molding.

In this case, the protrusion split molds 23, 23 are replaced by the main body split molds 22, 23, as shown in FIGS. 3 and 5.
Leave it open even further.

When the molding of the parison 29 is completed, the main body split molds 22, 22 are closed, the parison 29 is housed in the cavity, and the lower end is closed to prevent air from being pulled out, although not shown.

In this state, the main body split molds 22, 22 are closed by touching the parting line, but the protrusion split molds 23,
23 is open. Next, the parison 29 is blown with air, but since the purpose of this air blow is to partially expand the parison, the air pressure may be low. The parts located at 22, 22 expand to the mold surface, but the parts located at 23, 2 for protrusions
The portion 29a located at 3 is the protrusion split mold 23, 2
Since the mold surface of No. 3 is at a position farther back than the mold surfaces of the main body split molds 22, 22, the cutter 27 expands greatly beyond the position of the cutter 27 between the protruding split molds.

Then, when the protrusion split molds 23, 23 are closed, the bulging portions 29b, 29b are removed from the protrusion split molds 23, 23, respectively.
It is crushed flat by the mold surface 23, and at the same time, the extra length is cut off by the cutters 27, 27, and rectangular protrusions 12, 12 as shown in FIG. 2 are formed in the cutouts.

Once the formation of the projections 12, 12 is completed,
Air blowing is performed again to blow mold the parison 29 into the hollow body 11 shown in FIG.

In addition, although the above example is a case in which protrusions are integrally formed on both sides of a cylindrical blow product, the shape of the blow product is not limited to the cylindrical shape, and the protrusions can also be formed on blow products with a complex external shape by the same means. can be formed. Moreover, if necessary, the protrusion 12 can be formed hollow.

As described above, this invention includes a protrusion split mold that is slidably incorporated into a split mold for molding the main body, and when the protrusion mold is opened, the parison is partially bulged out at the required location in the blow mold. Also, by closing the mold, the bulging part is formed into a flat shape, and the extra length protruding from the cutter position is cut by the cutter to form a protrusion of the desired shape, and the protrusion is integrated into the side of the blown product. Therefore, there is no need to make the width of the parison particularly large in order to form the protrusions. In addition, the parison expands uniformly around the entire circumference, and the protrusion is formed by closing only the split mold for the protrusion, so protrusions with uniform thickness distribution can be formed without the need for large mold closing force. Since the parison is not cut away by the blow mold, that is, the parting line of the pair of split molds, there is almost no burr generation and almost no finishing work is required.

Moreover, the split mold for the protrusion can be removed from the split mold for the main body and replaced with another one, so even if the shape of the protrusion changes, the main body can be used as is, and there is no material loss, making it highly economical. It has many advantages over conventional methods, such as the appearance of the product is good because there are no cut marks, and it is not limited to the external shape of the molded product.

Furthermore, as can be seen from FIGS. 5 and 6, since the entire protrusion mold moves, the thickness of the main body does not become uneven due to protrusion molding, and a molded body having a uniform thickness can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a blown product with protrusions manufactured using the conventional method, FIG. 2 is a perspective view of a blown product with protrusions manufactured using the present invention, and FIGS. 3 to 6 are manufactured using the present invention. 3 is a schematic vertical sectional view of the blow mold when the split mold is closed, FIG. 4 is a front view of one of the split molds and the protrusion split mold, and FIG. A sectional view taken along the line V-V, and FIG. 6 is a sectional view of the same mold when air blowing is completed when the split mold for protrusions is closed. 11...Hollow body, 12...Protrusion, 21...Blow mold, 22...Split mold for main body, 23...Split mold for protrusion, 27...Cutter, 29...Parison, 29
a... Swelling part, 29b... Swelling part.

Claims (1)

[Claims] 1. A method for manufacturing a hollow molded product having a protrusion on the side surface, comprising: two pairs of split molds for molding the main body placed above and below the protrusion, and a cutter protruding from the mold surface to form a notch corresponding to the protrusion. A parison extruded or injected into the blow mold using a blow mold consisting of a protrusion split mold which is sandwiched between the main body split molds so as to be openable and closable at right angles to the flow direction of the parison. Close only the split mold for the main body and temporarily blow with air, and the air blow causes the part of the parison located in the split mold for protrusions to bulge out between the split molds for protrusions, and then close the mold and close the mold surface. The bulging part is formed into a flat shape, and the extra length protruding from the notch is cut with the cutter to form a protrusion of the desired shape, and the product is completed by air blowing. A manufacturing method for blow products with characteristic protrusions.