JPH06360B2 - Blow molding equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a blow molding apparatus for molding a hollow product.

[Prior Art] Conventionally, as a device for molding a hollow product, there is a blow-molding device for a ring plunger type head as shown in FIGS. 8 and 9.

In such a blow molding device of a ring plunger type head, a cylindrical parison is injected, and the upper and lower parts of the parison are pinched by a mold a and then blow molding is performed.

Furthermore, as another device (not shown) for molding a flat blow-molded product, two plate-shaped parisons are faced to each other and injected, and the two parisons are blow-molded by pinching the entire circumference with a mold. There is something.

[Problems to be solved by the invention] However, in the former device, (I) when the upper end of the mold a is brought close to the lower end of the nozzle b, the parison c is cut off from the nozzle b before being pinched. Therefore, the distance S between the upper end of the die a and the lower surface of the nozzle b needs to be 1/2 or more of the diameter D of the nozzle b, and pinch wrinkles occur.

(II) When the parison c has a large diameter, the lower end of the parison c after being pinched is curved, so it is necessary to make the part L longer to allow it. The L portion and the interval S both became burrs and reduced the yield.

(III) When making a flat shape with a ring plunger type head, it was difficult to obtain a flat shape at a uniform circumferential extrusion speed.

There were problems such as.

In the latter device, the intervals S and L shown in FIG. 9 can be shortened, but a pinch portion is formed over the entire circumference, and a sufficient connection cannot be obtained, and the thickness of the pinch portion is thin and strength is high. There is a problem that the appearance is not sufficient and the appearance is not good.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems of the prior art, and is a parallel two unit facing the parison head body.
A flat hole was formed by connecting the surfaces with a semi-cylindrical curved surface, a plunger was slidably fitted in the flat hole, and a mandrel was slidably penetrated through the plunger, and the mandrel lower end and the lower surface of the parison head body were provided. An injection slit similar to the flat hole shape is formed by a nozzle, and the plunger is connected to the injection cylinder.

[Operation] When the space defined by the parison head body and the mandrel is filled with resin, the flat cylinder parison is ejected from the injection slit when the plunger is pushed by the injection cylinder.

[Examples] Examples of the present invention will be described below with reference to the drawings.

A flat hole 2 is formed by connecting two parallel surfaces facing the parison head body 1 with a cylindrical curved surface, and the flat hole 2 has a plunger 3
A mandrel 4 is slidably fitted by slidably fitting the mandrel 4 and a hole similar to the flat hole 2 in the plunger 3. The tip of the mandrel 4 is gradually expanded downward in a skirt shape, and its outer shape is similar to the flat hole 2. A flat ring-shaped injection slit 5 is formed between the lower end of the parison head body 1 and the tip of the mandrel as shown in FIG.
The nozzle 6 for forming the is fixed.

A substrate 8 is attached to the upper surface of the parison head body 1 via a guide rod 7, and a slide plate 9 is attached to the guide rod 7.
Is slidably provided, and the slide plate 9 and the plunger 3 are connected by a tie rod 10. The injection cylinder 11 and the parison control cylinder 12 are attached to the substrate 8, the rod of the injection cylinder 11 is fixed to the slide plate 13, and the rod of the parison control cylinder 12 allows the slide plate 13 to loosen and the lower end thereof is fixed to the mandrel 4.

When injecting a parison, the injection cylinder 11 is set free, the space formed by the head body 1 and the mandrel 4 is filled with resin while pushing up the plunger 3, and then the plunger 3 is pushed down by the injection cylinder 11 to produce an injection slit. A flat cylindrical parison is ejected from 5.

The parison thickness accuracy is controlled by moving the mandrel 14 up and down by the parison control cylinder 12 to adjust the clearance of the injection slit 5.

Then, if the parison is pinched from the minor axis direction by a die, S shown in FIG. 6 can be remarkably shortened and a flat one can be pinched, so that the lower end is less curved and the L portion can be shortened and pinched wrinkles. Is almost gone. Therefore, in the conventional example, the burr occupies about 30% of the total length of the parison, but in this embodiment, it can be reduced to 5% or less. Further, the appearance is improved by eliminating pinch wrinkles, and the parison is not distorted at the time of pinch pinching, so the wall thickness accuracy is improved.

Further, in this embodiment, there is no pinch portion in the parison injection direction, the appearance is good and the strength is increased.

Next, referring to FIGS. 5 to 7, the flat cylindrical plunger is shown.
An example of the manufacturing method of 3 will be described.

First, the plunger 3 is constructed by combining a pair of flat portions 15 and 16 and a pair of semi-cylindrical portions 17 and 18 divided into four parts.
This united structure makes it extremely easy to form the flat hole 2 through which the mandrel 4 is inserted. The pair of flat portions 15 and 16 and the semi-cylindrical portions 17 and 18 are fastened with bolts 19, and the semi-cylindrical portions 17 and 18 are connected.
Make a hole so that the head of the bolt 19 is completely immersed from the surface. After screwing the bolts 19 into the holes 20 and place the hard solder (eg silver solder) 21
Fill the surface with and smooth the surface. At this time, the filled hard wax
A groove 22 or a protrusion (not shown) is provided on the inner surface of the hole 20 to prevent the hole 21 from falling off.

The smooth finish of the hole 20 described above may be only the lower end of the plunger 3 that affects the injection of the parison.

Further, the method of manufacturing the plunger is not limited to the above method.

[Effects of the Invention] As described above, according to the present invention, (i) the mold can be brought closer to the nozzle and the amount of projection below the mold can be reduced, so that burrs are significantly reduced and the yield is improved. (Ii) The appearance of the parison is improved by eliminating the bending, pinch wrinkles and the pinch part on the entire circumference. (Iii) The pinch part is only the upper and lower ends, so the strength is improved and the product reliability is also improved. It exhibits excellent effects such as increase.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment according to the present invention, and FIG.
FIG. 3 is a bottom view of the embodiment, FIG. 4 is a perspective view of the plunger, and FIGS. 5 to 7 show a method of manufacturing the plunger. FIG. Explanatory drawing, FIG. 6 is the fifth
FIG. 7 is an enlarged view of a C portion, FIG. 8 is a side view of a conventional example, and FIG. 9 is a front sectional view of the same. 1 is parison head body, 2 is flat hole, 3 is plunger, 4
Is a mandrel, 5 is an injection slit, and 11 is an injection cylinder.

Claims (1)

[Claims] 1. A flat hole in which two parallel surfaces facing the parison head body are connected by a semi-cylindrical curved surface is bored, a plunger is slidably fitted in the flat hole, and a mandrel is slid on the plunger. A blow molding apparatus, characterized in that an injection slit similar to the flat hole shape is formed by a nozzle provided at the lower end of a mandrel and a lower surface of a parison head main body, and a plunger is connected to an injection cylinder.