JPH091640A - Blow molding method and device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a blow molding method and apparatus for adjusting a wall thickness by controlling a parison and obtaining a larger molded product from the parison in which the parison is incised and widened. . A parison 23 extruded from a discharge port 22 of a blow molding machine head 21 is continuously incised by a cutting means 24, and both ends of a tip 26c of the incised parison 23 are clamped and folded back in a U shape. At the same time, the U-shaped parison 23 is clamped with a blow molding die 30, and a gas body or the like is blown into the parison 23 for molding. As the device, a head 21 having a cutting means for cutting the parison 23 in the pushing direction, a pair of blow molding dies 30, and both ends of the incised parison 23 are clamped and opened to the plate-shaped body 26. The first clamping means 27a, the second clamping means 27b which clamps and opens both sides of the parison 23 near the head 21, and the molding die clamping parison 2
A blow molding device comprising a gas body blowing device 31 for applying an internal pressure to 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding method for a synthetic resin container or the like, and more particularly to a blow molding method and apparatus for cutting a parison into a plate-like body. .

[0002]

2. Description of the Related Art Conventionally, for example, as shown in FIG.
There is something like that shown in This is JP-A-55-101
This is described and disclosed in Japanese Patent No. 415.

In this blow molding method of synthetic resin,
As shown in FIG. 4 (a), one cutting blade fixed to the bar member 4 in order to cut and form the parison 3 into a plate-like body at the discharge port 2 between the mandrel 1 and the die 11 of the extruder. 5 is installed in the discharge port 2.

Therefore, as shown in FIG. 4 (b), the parison 3 is cut while being pushed out from the discharge port, and the plate-like body 3a is cut.
Then, the plate-like body 3a is pressed against the concave surface 8 of the mold 6 by immediately closing the mold with the mold 6 and blowing the air or gas body from the ventilation hole 7 to form the convex-shaped molded product 9. The law is disclosed.

Further, in this Japanese Laid-Open Patent Publication No. 55-101415, by cutting the parison 3 from two places, two plate-like bodies 3a can be obtained and at the same time two convex shaped articles 9 can be formed. A molding method is also disclosed at the same time.

[0006]

However, although the conventional synthetic resin molding method shown in FIG. 4 discloses that a molded product of the plate-like body 3a is produced, the incised parison is formed into a U-shape. There is no disclosure of folding back to double, and there is a drawback that a molded article of a hollow body cannot be produced.

Further, in the conventional one, the cutting blade 5 has the discharge port 2
It is not applicable to the so-called parison control type molding method in which the tapered mandrel for adjusting the wall thickness of the parison 3 is moved up and down to change the discharge port to change the parison wall thickness during molding.

Therefore, the intervals between the discharge ports 2 are always constant, and the wall thickness cannot be increased only where strength is required. Therefore, the weight is increased to thicken the whole, and conversely, it is desired to reduce the wall thickness. There was a problem that it was difficult to guarantee the quality of the molded product because the parison 3 became thin due to the drawdown of the parison 3 and insufficient strength often occurred.

Therefore, an object of the present invention is to provide a blow molding method and apparatus for adjusting the wall thickness by controlling the parison and obtaining a larger molded product from the parison in which the parison is cut and widened. .

[0010]

In order to achieve the above-mentioned object, the invention described in claim 1 continuously cuts a parison extruded from a discharge port of a blow molding machine head by a cutting means, Both ends of the incised parison are clamped and folded back into a U-shape, and this U-shaped parison is clamped with a blow molding die, and a gas body or the like is blown into the parison for molding. Blow molding method.

According to a second aspect of the present invention, in the blow molding method according to the first aspect, in the discharge port portion having the cutting means, the die and the mandrel have different taper toward the discharge port. The mandrel is vertically movable.

According to a third aspect of the present invention, in the blow molding method according to the first aspect, the U-shape of the parison is located at a position above the lower biting part in a state where the mold for blow molding is opened. It is characterized in that a folded portion is provided.

According to a fourth aspect of the present invention, a parison is pushed out from between the die and the mandrel, and a head having a cutting means for cutting the parison in the pushing direction to open the parison, and below the head is provided. A pair of opposed blow molding dies sandwiching the parison, first clamping means for clamping both sides of the tip end of the parison cut out in the mold open state of the blow molding dies to open into a plate-like body, and Second clamping means for clamping and opening both sides of the parison in the vicinity of the head so as to face the dissected parison in U-shape in cooperation with the clamping means,
And a gas body blowing device which applies an internal pressure to the parison when the molding die of the blow molding die is clamped.

According to a fifth aspect of the present invention, in the blow molding apparatus according to the fourth aspect, the cutting means is mounted so that the cutter always crosses between the die and the mandrel. I am trying. According to a sixth aspect of the present invention, in the blow molding apparatus according to the fourth aspect, a guide separator is provided near a lower portion of the blow molding machine head to facilitate opening of the cut parison. It has a feature.

According to a seventh aspect of the present invention, in the blow molding apparatus according to the fourth aspect, the U-shaped parison sandwiching shutter is provided on at least one of the parting surfaces of the blow molding die. It is characterized by that.

The invention described in claim 8 is the blow molding apparatus according to claim 7, characterized in that a notch is provided in the parison holding surface of the shutter.

[0017]

According to the first aspect of the present invention, the parison is continuously incised by the cutting means, both ends of the parison are clamped, and the U-shaped parison is folded back into a U-shape. By molding with a mold and blowing a gas body or the like into this parison, it is possible to obtain a blow-molded product having a peripheral length about twice that of the conventional parison. Therefore, it is possible to mold a larger molded product with a small blow molding machine.

Further, since the parison can be incised while controlling the parison, it is possible to form a molded product having an appropriate wall thickness suitable for the strength.

According to a second aspect of the present invention, the die and the mandrel have different taper toward the discharge port, and the mandrel is provided so as to be movable up and down, so that the gap between the discharge ports is changed and the molding is performed. The wall thickness can be adjusted according to the strength of each part of the product.

According to a third aspect of the present invention, the U-shaped folded-back portion of the parison is arranged at a position above the lower cut-out portion in the opened state of the blow molding die. The material yield is improved without the generation of scraps due to cutting, and the strength can be improved as compared with the cut portion.

According to a fourth aspect of the present invention, the parison is pushed out from between the die and the mandrel which are the discharge ports, and the head has a cutting means for cutting the parison in the pushing direction, and the head, and the head. A pair of opposing molds for blow molding sandwiching the parison below, and first clamping means for clamping both ends of the parison cut in the mold open state of the blow mold to open the plate-shaped body. A second clamp means for clamping and opening both sides of the parison near the head in order to face the incised parison in a U-shape in cooperation with the first clamp means, and molding of the blow molding die. The device of the present invention is constituted by a gas body blowing device which applies an internal pressure to the parison during mold clamping.

In the invention described in claim 5, as the cutting means, the cutter is mounted so that it always crosses between the die and the mandrel, and the parison control is activated to adjust the wall thickness at all times. You can cut the parison.

According to the sixth aspect of the invention, a guide separator is provided near the lower part of the blow molding machine head to facilitate opening of the cut parison. The parison extruded while being incised into is greatly spread by the separator and surely becomes a plate-like body.

According to a seventh aspect of the present invention, the U-shaped parison holding shutter is provided on at least one of the parting surfaces of the blow molding die.
Since the periphery of the parison is sandwiched and a gas body or the like can be blown in without leaking, the U-shaped parison can be blow-molded without sticking to each other.

According to the eighth aspect of the present invention, when the mold is vacuumed and molded from the cavity side, since the notch is provided on the parison holding surface of the shutter, even if the parison is held by the shutter, the notch is formed. However, air can be drawn into the parison without adhering to each other, so that the U-shaped parison can be prevented from adhering to each other.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

1 to 3 show an embodiment of the present invention.

FIG. 1 is a perspective view showing the structure of the present invention. In the figure, reference numeral 21 is a blow molding machine head, and a discharge port 22 is provided at the bottom of the blow molding machine head 21. The discharge port 22 is provided with a gap between the die 22a and the mandrel 22b, which are substantially concentric when viewed from below. As shown in the sectional view of FIG. 2, the die 22a and the mandrel 22b respectively face the discharge port 22. The mandrel 22b is vertically movable.

The taper direction between the die 22a and the mandrel 22b is a so-called diverge type (shown in FIG. 2) in which the cross-section is divergent toward the end. May apply. In both of these, this mandrel 2
The gap between the discharge ports 22 is adjusted by operating the 2b up and down.

A cutter 24a as a cutting means 24 is provided at the discharge port 22 as a die 22a and a mandrel 22b.
It is mounted so as to cross between the spaces.

The cutter 2 which is the cutting means for the discharge port 22
The mounting structure of 4a will be described with reference to FIG.

In the one shown in FIG. 2A, the cutter 24a has a mandrel 22 from the side of the die 22a by a spring 24b and the like.
It is provided so as to be pressed against b. The sectional view on the left side shows the die 22a and the mandrel 22b in the normal position, and the right figure shows the position where the mandrel 22b is lowered by the parison control and the gap of the discharge port 22 is widened.

The one shown in FIG. 2B corresponds to the one shown in FIG.
Contrary to (a), it is provided so as to be pressed against the die 22a from the mandrel 22b side by the spring 24b. The left figure shows the normal position of the mandrel 22b, and the right figure shows the position where the ejection port 22 is widened by parison control.

Further, what is shown in FIG. 2 (c) is a die 2
The cutter 24a fixed to the mandrel 2b slides through the slit of the cutter 24a provided on the mandrel 22b.
It is provided so as to always cross the discharge port 22 even if 2b is vertically movable. The left figure shows the normal position of the mandrel 22b, and the right figure shows the position where the ejection port 22 is widened by parison control.

The cutting means 24 shown by the dotted line shows the case where the cutter 24a is mounted on the mandrel 22b, and has the same operation as when the cutter 24a is mounted on the die 22a.

Further, the parison 23 having the separator 25 mounted in the vicinity of the lower portion of the discharge port 22 is spread to the left and right through the mounting portion provided on the blow molding machine head 21. Subsequently, the first clamping means 27 for clamping both sides of the tip 26c of the parison 23 which has become the plate-like body 26.
a and a second clamp means 27b for clamping both sides of the folded back end of the parison are provided.

Molds 30 are provided on both sides of the U-shaped parison 23, respectively. At least one mold 30 of the left and right molds 30 is provided with a sandwiching shutter 30e protruding from the parting surface 30d. A plurality of springs 30f are embedded on the back side of the shutter so as to push up the shutter 30e.

Further, a gas body blowing device 31 is provided near the lower portion of the U-shaped folded portion 26b. The gas body blowing device 31 is mainly composed of an air cylinder 31a and an air pin 31b, and the air pin 31b is vertically movable.

Incidentally, it goes without saying that the installation position of the gas body blowing device 31 can be selected not only in the lower part of FIG. 1 but also in the upper position or the lateral position according to the shape of the molded product.

Next, a blow molding method having such a structure will be described.

As shown in FIG. 1, the blow molding machine head 2
The parison 23 extruded to a proper thickness by continuously moving the mandrel 22b from the discharge port 22 of No. 1 is continuously cut by the cutting means 24, and the cut parison 23 is further spread by the separator 25. At the same time, the both ends of the plate-like body 26 are clamped by the first clamping means 27a to push out the parison 23 having the set amount of resin, and the plate-like body 26 is hung down and folded back to form a U-shape. Blow molding machine head 21
The vicinity of the lower part is further clamped from the left and right by the second clamp means 27b.

Then, while closing the mold 30, the shutter 30e provided on the mold 30 first holds the double plate-like body 26 and blows a low-pressure gas body or the like, or sucks vacuum from the cavity side of the mold. After preventing the adhesion of the plate-shaped bodies 26 on both sides, the air pin 31b of the gas-body blowing device 31 is advanced between the double plate-shaped bodies 26 while completely clamping the mold to blow the gas body and the like, It is molded by applying molding pressure.

When the double plate-shaped body is sandwiched by the shutter and sucked from the cavity side of the mold, the cutout provided on the holding surface of the shutter is bent by being sucked into the cutout 30h. It will form a hole to attract air and prevent adhesion.

Further, by controlling the parison during extrusion of the parison 23, the mandrel 22b is lowered where the molded product partially needs strength, and the discharge port 22 is widened to have a thicker wall. The thickness of the parison 23 can be changed according to the required strength of the molded product, for example, by raising 22b to narrow the discharge port 22 to make it thinner.

The main molding steps of this blow molding method are as shown in FIGS. 3 (a), (b), (c) and (d): (1) First step (FIG. 3 (a)): blow molding machine Head 2
A step of disposing the parison 23 extruded from the discharge port 22 of No. 1 and placing the double plate-like body 26 between the left and right molds 30 by hanging and folding back the parison 23, (2) Second step (FIG. 3B): A shutter 30e in which the double plate-shaped body 26 is provided on the parting surface 30d of the mold 30.
(3) Third step (FIG. 3 (c)): step of clamping the mold and blowing in a gas body having a molding pressure, and the like. 4) Fourth step (FIG. 3 (d)): a step in which the mold 30 is fully expanded and molded, and then cooled, and the molding is completed by opening the mold and demolding. .

[0046]

As described above, according to the invention described in claims 1 to 3, the parison is continuously incised by the cutting means and further spread by the separator. Both ends of the plate-like body of the parison are expanded. Is clamped and folded back into a U-shape, the mold is clamped with a blow molding die, and a gas body or the like is blown into this double plate-shaped body for molding.

Therefore, it is possible to obtain a blow molded product having a peripheral length about twice that of a conventional parison which is not cut.

Further, by using the parison control which has been impossible in the past, it is possible to freely manufacture a molded product having an appropriate wall thickness suitable for strength. Therefore, a lightweight molded product having appropriate strength can be obtained.

Furthermore, by disposing the U-shaped folded portion at a position above the lower cutting portion of the blow molding die,
The material yield is improved without the generation of scraps due to bite cutting.
There is no reduction in strength due to biting.

In the invention described in claims 4 to 8, a head having a cutting means for cutting the parison, a pair of opposed blow molding dies sandwiching the parison, and a plate-like body for clamping both sides of the front end of the parison. The first compact opening means, the second clamping means for opening both sides of the parison near the head, and the gas blowing means for applying an internal pressure to the parison. The blow molding machine has been used to make a device for molding larger molded products. Therefore, it is an energy-saving device capable of molding a larger product with a small machine.

Further, in this apparatus, the cutter cuts the parison, and the separator subsequently expands, so that the parison surely becomes a plate-like member, which can be sandwiched by the shutter and expanded. Also, when suction molding is performed from the cavity side of the mold, the cutout portion of the shutter pulls in a part of the plate-like body,
This is a device that can prevent air from adhering to the plate-like body from the position where it is drawn in and prevent adhesion, thus ensuring reliable molding.

[Brief description of the drawings]

FIG. 1 is a perspective view of a blow molding method showing an embodiment of the present invention.

2 (a) to (c) is a sectional view showing the cutting means of the same FIG. 1A part of the same embodiment of the present invention.

FIG. 3 (a) to (d) are main cross-sectional views showing a blow molding process of the same example of the present invention.

4 (a) and 4 (b) are plan views showing a method of forming a plate-shaped body of a conventional example.

[Explanation of symbols]

 21 ... Blow molding machine head 22 ... Discharge port 23 ... Parison 24 ... Cutting means 25 ... Separator 26 ... Plate-like body 26b ... U-shaped folded-back part, 26c ... Tip part 27 ... Clamp part 27a, 27b ... First, second Clamping means, 30 ... Blow molding die 30d ... Parting surface, 30e ... Shutter 30h ... Notch portion 31 ... Gas body blowing device

Claims (8)

[Claims] 1. A parison extruded from a discharge port of a blow molding machine head is continuously incised by a cutting means, both ends of the incised parison are clamped, and the parison is folded back in a U-shape. A blow molding method characterized by clamping a character-shaped parison with a blow molding die and blowing a gas body or the like into the parison. 2. The discharge port portion having the cutting means, wherein the die and the mandrel have different taper toward the discharge port, and the mandrel is vertically movable. The blow molding method described. 3. The blow according to claim 1, wherein a U-shaped folded-back portion of the parison is arranged at a position above the lower cutting portion in the opened state of the blow molding die. Molding method. 4. A head having a cutting means for pushing a parison between the die and the mandrel and cutting the parison in the pushing direction to cut the parison, and a pair of opposing blows sandwiching the parison below the head. A molding die, a first clamp means for clamping both sides of a parison cut in the opened state of the blow molding die to open a plate-like body, and an incision in cooperation with the first clamp means. U parison
Second clamping means for clamping and opening both sides of the parison in the vicinity of the head so as to face each other in a letter shape, and a gas body blowing device for applying an internal pressure to the parison when the mold for the blow molding die is clamped. A blow molding device comprising: 5. The blow molding apparatus according to claim 4, wherein the cutting means is mounted so that a cutter always crosses between the die and the mandrel. 6. Near the lower part of the blow molding machine head,
The blow molding apparatus according to claim 4, wherein a guide separator is provided to facilitate opening of the cut parison. 7. The blow molding apparatus according to claim 4, wherein the U-shaped parison sandwiching shutter is provided on at least one of the parting surfaces of the blow molding die. 8. The blow molding apparatus according to claim 7, wherein the parison holding surface of the shutter is provided with a cutout portion.