JPS5847337B2 - Blow molding method for bent products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of blow-molding a product having a bent shape such as a dogleg shape or an S shape using a split mold using a parison extruded downward from an extrusion die.

Conventionally, as a method for blow molding a dog-shaped product, for example,
While a pair of split molds having dogleg-shaped nests corresponding to the shape of the product are opened, the parison is pushed out and lowered, and the lower end of the parison is pinched by hand to bend the entire descending parison into a dogleg shape. A method is known in which the parison is bent into a dogleg shape to match the mold cavity, the two split molds are joined together, and then air is blown into the parison to perform blow molding.

However, with this conventional method, not only does it require a lot of skill to bend the parison into a dogleg shape that matches the mold cavity, but there is also the risk of serious injury if your hand gets caught in the split molds that join together. There was a demand for some new method to replace this.

The first aspect of the present invention is to provide a novel blow-molding method for bending products that can be safely operated without requiring any skill, in response to conventional demands.

The second and third inventions of the present application provide a blow molding method for a bent product that achieves substantially the same object as the first invention by using a method partially included in the first invention.

The present invention will be described in detail below with reference to the drawings.

First Invention A pair of split molds 1, 1 used in the present invention have a rectangular joining surface 7, 7, and a blown quarter face 2, 2 opening on the top surface of the split mold 1, as shown in the first figure. A dogleg-shaped nest half surface 3, 3 is formed which extends downward in a dogleg shape continuously with the blown quarter surface, and whose lower end is directed toward the lower corner of the joining surface 7, and the above blown quarter surface 2.
and a split mold upper part 4, 4 including the upper end of the mold cavity half surface 3, a split mold lower part 5, 5 including the lower end of the mold cavity half surface 3, and a split mold main part including the remaining bent mold cavity main part half surface 31. It is divided into 6,603 parts, of which a cooling jacket is installed in the split main part 6°6.

First, as shown in the second figure, the split mold main parts 6, 6 are attached to their joint surfaces γ.
, 7 are vertically oriented and attached to each other to form a mold cavity main part 8 with openings at both upper and lower ends inside.

Next, as shown in FIG. 3, the molten synthetic resin cylindrical parison 10 is extruded from the extrusion die 9 of the synthetic resin extruder and placed inside the mold cavity main part 8 of the split mold main part 6°6 which has been joined together. Then, the mold nest main part 8 is lowered by its own weight from the upper end of the opening, and a suction pipe 11 of a suction device is applied to the lower end opening of the mold nest main part 8 to apply a suction action to the outside inside the mold nest main part 8.

This suction action generates an airflow flowing from the upper end of the opening of the mold nest main part 8 to the lower end of the opening along the outer circumferential surface of the parison 10, whereby the descending parison 10 is guided by the airflow to the box-shaped nest main part 8. It is inserted into the portion 8 while being bent in a dogleg shape.

When the parison 10 passes vertically into the mold cavity main part 8 and the lower end of the parison protrudes from the lower end opening of the mold cavity main part by an appropriate length as shown in the fourth figure, the suction pipe 11 is removed and the parison 10
After stopping the extrusion, as shown in Figure 5,
and the lower parts 5, 5 are joined to the upper and lower parts of the joined split mold main parts 6, 6, respectively, thereby forming a pair of joined split molds 1, 1, with the desired complete shape inside. While forming a mold nest, the parison 10 is held between the air blowing pins 12 which hang down from the center of the extrusion die 9 by the blowing quarters 2, 2 of the split mold upper parts 4, 40 being joined together. Closed and parison 1 depending on the lower part of the split mold 5,50 pieces
Close the open lower end of 0 by pinching it.

Then, the air pin 12 blows air into the parison in the mold cavity to inflate the parison and perform the desired molding.

After molding, the parinon is cut from the extrusion die, and then the two split molds 1, 1 are opened to obtain a molded product W bent into a dogleg shape with a tab at both ends as shown in FIG.

Second Invention The present invention has a structure in which air is blown from the lower end of the parinon, and the pair of split molds Ia and 1a used have a blow quarter surface 2a and an upper part 4a of the split mold, as shown in FIG. Instead, it is provided in the split mold lower part 4a so as to be continuous with the lower end of the mold cavity half surface 3a and open to the outside, and for sucking and inserting the parison 10a, as shown in FIG. Using an air device 13a in which a suction tube 11a having an inner diameter larger than the outer diameter is slidably fitted, this suction tube 1
With the tip of the air pin 1a in contact with the lower end opening of the mold cavity main part 8a and the tip of the air pin 12a brought close to the lower end opening, a suction action is exerted from the suction pipe 11a into the mold cavity main part 8a to mold the parison 10a. It is inserted into the nest main part 8a, and the open lower end of the parison 10a is fitted onto the outside of the air pin 12a, and then when the parison is inflated,
As shown in FIG. 9, the suction pipe 11a is retreated along the air pin 12a, and the split mold upper parts 4a, 4a and lower parts 5a, 5a are removed.
are bonded together, and blow molding is performed by blowing air into the parinon from the air pin 12a.Other configurations are substantially the same as the first invention.

According to the first and second inventions of the present application, it is possible to smoothly insert parinon into mold cavities of various bent shapes without requiring any skill, thereby safely and reliably mass producing bent products of good quality. It is possible to do so.

Third invention As shown in FIG. 10, the pair of split molds 1b, 1b used in the present invention have a rectangular joint surface 7b, 7b, and a blown quarter surface 2b, 2b, which is open to the upper surface. Forming mold cavity half surfaces 3b, 3b that extend downward in an L-shape continuously, and sucking quarter surfaces 14b, 14b continuous with the lower end of the mold cavity half surface 3b and opening at the lower side surface of the split mold 21, Split mold upper parts 4b, 4b including the upper end portions of the blow quarter ff12b and mold cavity half surface 3b, and the remaining split mold main parts 6b, 6b
The split mold main parts 6b and 6b are each divided into two parts.
is equipped with a cooling jacket.

First, the parison 10b is slightly extruded from the extrusion die 9b.
A pair of pinch plates 15b, as shown in FIG.
15b, and at the same time, the unnecessary parts are cut and separated.

Next, as shown in the twelfth figure, the split mold main portion 6b is formed.

6b are joined to each other with their joining ff17b and 7b facing vertically, thereby forming a mold cavity main part 8b with an open upper end and a closed lower end, and communicate with the lower end of the mold cavity main part 8b. A suction port 16b that opens to the outside is formed.

Next, as shown in Figure 13, the pinon 10b with its lower end closed is pushed out and lowered by its own weight into the mold nest main part 8b from its open upper end, and the suction pipe 11b of the suction device is applied to the suction port 16b. This applies a suction action to the outside within the mold cavity main portion 8b.

Due to this suction action, the parison 10b is inserted into the dogleg-shaped nest main portion 8b while being bent in a dogleg shape (as in the first invention).

When the lower end of the parison 10b reaches the lower end of the mold cavity main part 8b, remove the suction pipe 11b and stop extruding the parison 10b, and then move the split mold upper part 4b as shown in FIG.
, 4b are joined to the upper parts of the joined split mold main parts 6b, 6b, thereby forming a pair of joined split molds 1b, 1b to form a complete mold nest therein. Upper part 4b
, 4b clamps and closes the binon 10h while clamping the air pin 12b with its blown quarters 2b, 2b.

Next, air is blown into the parison in the mold cavity from the air pin 1.2b to inflate the parison and perform the desired molding.

The resulting molded product has no cracks at the lower end as shown in Figure 15.

According to the second invention of the present application, it is possible to obtain the same effects as the first invention and also to form a bent product without forming a burr at the lower end.

[Brief explanation of drawings]

1 to 6 show an embodiment of the first invention of the present application, FIG. 1 is a perspective view of a pair of split molds, FIG. 2 is a perspective view of the main parts of the split molds when joined together, and FIG. 3 is a perspective view of a parison. Figure 4 is a slope view when the suction insertion is completed, Figure 5 is a slope view when the split molds are joined together, Figure 6 is a slope view of the molded product, and Figures 7 to 9 are slope views. Fig. 7 shows a part of the second invention of the present application, Fig. 7 is a perspective view of the split mold, Fig. 8 is a cross-sectional view when the suction insertion of the parison is completed, showing the parison with imaginary lines, and Fig. 9 shows the parison with imaginary lines. Figures 10 to 15 show an embodiment of the third invention of the present application, Figure 10 is a slope view of a pair of split molds, and Figure 11 is a slope view when the lower end of the parinon is closed. , Fig. 12 is a perspective view of the main parts of the split molds when they are joined together, Fig. 13 is a perspective view of the parison when it is inserted by suction, Fig. 14 is a perspective view of the split molds that are joined together, and Fig. 15 is a perspective view of the molded product. It is a slope view. 1.1a, 1b... split mold, 2, 2 a, 2
b---Blow quarter side, 3, 3a, 3b...Katasu half side, 3.

Claims (1)

[Scope of Claims] 1 A pair of split molds each having a blown quarter surface opening at the upper end of the joining surface and a curved mold nest half surface continuous with the blown quarter surface, each split mold having the above blown quarter surface. It was divided into three parts: an upper part of the split mold including the upper end of the quarter surface and the upper end of the half of the mold nest, a lower part of the split mold including the lower end of the half of the mold cavity, and a main part of the split mold including the remaining half of the main part of the bent mold cavity. Using a mold, a pair of split main parts of the molds are joined together with their joining surfaces substantially perpendicular to form a mold cavity main part with openings at both ends at the top, and a parison. is inserted downwardly into the mold cavity main part from the upper end of the opening, and a suction action is applied to the outside from the opening lower end of the mold cavity main part, whereby the parison is inserted into the bent mold cavity main part; When the lower end protrudes appropriately from the lower end of the opening of the main part of the mold cavity, the upper and lower parts of the pair of split molds are joined together and the upper and lower ends of the parinon are clamped and closed. A bent product comprising the following steps: holding an air blowing pin between a pair of blow quarters at the top of the split mold, and blowing air into the parison from the air blowing pin to blow mold it. blow molding method. 2 A pair of split molds each having a mold cavity half surface bent at the joining surface and a blown quarter surface opening to the outside continuously from the lower end of the mold cavity half surface, each split mold having an upper end of the mold cavity half surface A mold is used which is divided into three parts: an upper part of the mold containing the above-mentioned blown quarter surface and the lower end of the half surface of the mold cavity, and a main part of the divided mold including the remaining half surface of the main part of the bent mold cavity. , A pair of split mold main parts of the molds are joined together with their joining surfaces substantially perpendicular, and a mold cavity main part with openings at both ends is formed inside, and Parinon is attached to the mold cavity main part The parison is inserted downwardly into the mold cavity from the upper end of the opening, and a suction action is applied to the outside from the opening lower end of the mold cavity main part, whereby the parison is inserted into the bent mold cavity main part, and the lower end of the parison is inserted into the mold cavity main part. When it protrudes appropriately from the lower end of the opening of the main part of the nest, the upper and lower parts of the pair of split molds are joined together to clamp and close the upper and lower ends of the parison, and the lower parts of the pair of split molds are held together. A blow-molding method for a bent product, which comprises: holding an air blowing pin between a pair of blowing quarters; blowing air into the parison from the air blowing pin and blow-molding it. . 3 The bonding surface has a blown quarter surface that opens to the outside at its upper end, a bent mold cavity half surface that is continuous with the blown quarter surface, and a sucking quarter surface that is continuous with the lower end of the mold cavity half surface and opens to the outside. A pair of split molds, each split mold having an upper part of the split mold including the upper end of the blown quarter face and the upper end of the mold nest half face, and a split mold main part including the remaining curved mold nest main part half face and the blown quarter face. Using a mold divided into two parts, the lower end of the parison is closed, and the main parts of the pair of split molds are joined with their joining surfaces almost perpendicular, and the upper end is placed inside. forming an open mold cavity main part and a suction port; lowering and inserting the parison with the lower end closed into the mold cavity main part from the upper end of the opening; and creating a suction action from the suction mouth to the outside in the mold cavity main part. In addition, the above-mentioned parison is thereby inserted into the bent mold cavity main part, and when the lower end of the above-mentioned parison reaches the lower end of the mold cavity main part, the pair of split mold upper parts are joined together, and the upper end of the parison is a pair of blown quarters and a pair of blown quarters to sandwich and close an air blowing pin, and blowing air into the parison from the air blowing pin to blow-form the parison. Blow molding method for bent products.