JPH0479292B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blow molding head used for extruding molten resin into a pipe shape and molding various containers and the like.

[Conventional technology]

An example of a conventionally used blow molding head will be explained with reference to FIG. 6. A is a head body, and a molten resin inlet b is provided on the upper side surface of the head body, and a molten resin inlet b is provided at the lower end of the head body a. , nozzle c is attached. A mandrel d is attached to the center of the head body a, and a flow pin e is fitted to the upper outer periphery of the mandrel d. Head body a
A slit f is formed between the outer circumference of the flow pin e and the upper end of the slit f is the molten resin inlet b.
The lower end of the slit f is connected to a nozzle outlet slit g formed between the nozzle c and the lower end of the mandrel d. As shown in FIG. 7, the nozzle outlet slit g has a uniform width of a perfect circle.

The molten resin entering from the molten resin inlet b passes through the slit f and is extruded from the nozzle outlet slit g as a parison h. Since the pressure of the molten resin between the molten resin inlet b side of the slit f and the back side of the slit f shown in FIG. The thickness of the parison h extruded from the nozzle outlet slit g is not uniform, resulting in a parison h with uneven thickness as shown in FIG. In order to prevent the wall thickness from shifting to the shoulder, the nozzle exit slit g should not be a perfect circle with a uniform width.
Install the nozzle c eccentrically, or sharpen one or both of the nozzle c and the mandrel d to enlarge a part of the nozzle outlet slit g,
A parison h was extruded that had a uniform thickness throughout.

Also, depending on the shape of the molded product, it may be necessary to change the wall thickness distribution of the parison, so the nozzle i may be made into a flexible ring using the above-mentioned die shaving (DIE/SHAVING) or the nozzle i may be made into a flexible ring as shown in Figure 9. A force is applied to the nozzle i by the actuator i disposed on both sides of the mandrel d, thereby deforming the circular nozzle i into an elliptical nozzle i. A method has also been adopted in which the thickness of the parison h in the circumferential direction is adjusted by changing the exit slit g into nozzle exit slits g having different thicknesses.

[Problem that the invention seeks to solve]

In the above-mentioned blow molding head shown in Fig. 6, the method of adjusting the wall thickness of the parison h by cutting one or both of the nozzle c and the mandrel d is to try the wall thickness of the parison h several times. Moreover, the parison h had to be made thick from the beginning to the end, and it was impossible to adjust the wall thickness in the length direction.

In addition, in the blow molding head using the flexible ring nozzle i shown in Fig. 9, the nozzle i returns to its original shape when the external force from the actuator i is removed, so that the lengthwise direction of the parison h is This device is more advanced than the device shown in Figure 6 because the wall thickness can be adjusted, but it is necessary to make a nozzle that fits each type of molded product, and if it is not made of a special alloy, it will lack elasticity. The production costs are high and the number of man-hours is high, and since the molded product always has two symmetrical thick-walled parts, there are problems such as unnecessary thick-walled parts depending on the type of molded product.

The present invention allows the slit at the nozzle exit to be a perfect circle even if the shape of the molded product is different, and allows the wall thickness of the molded product to be adjusted in the circumferential direction and length direction. This allows molded products to be molded.

[Means for solving problems]

The present invention has a flow pin provided in the head body, a slit formed between the head body and the outer periphery of the flow pin, and a slit between the outer periphery of the flow pin incorporated in the head body. A blower comprising: a throttle outer cylinder having a groove, a piece fitted into the groove of the throttle outer cylinder, and an actuator that slides the piece along the groove to move the piece closer to or away from the flow pin. It is used as a molding head.

[Effect]

When the piece is slid along the groove, the narrowed part of the slit changes, making it possible to adjust the partial thickness of the parison in the circumferential and longitudinal directions.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, a molten resin inlet 2 is provided on the upper side of the head body 1.
A mantrell 3 is provided at the center of the mantle, and a flow pin 4 and a ring plunger 5 are fitted to the outer periphery of the mantle in this order. 6 is a vertical parison control cylinder for raising and lowering the mandrel 3, 7
is an injection cylinder for raising and lowering a ring plunger 5, and a slit 8 is formed between the head body 1 and the outer periphery of the flow pin 4, and the upper end of this slit 8 is connected to the molten resin inlet 2. A constriction outer cylinder 9, a lower head main body 10, and a nozzle 11 are attached to the lower side of the head main body 1 in this order.

As shown in FIG. 2, the throttle outer cylinder 9 is provided with a large number of radial grooves 12 centered around the flow pin 4, and a piece 13 is fitted into each groove 12. The inner surface of the bridge 13 is formed into an arc that is the same as the inner diameter of the throttle outer cylinder 9, and when the inner surface of the bridge 13 is aligned on the same circumference as the inner diameter of the throttle outer cylinder 9, the outer circumference of the flow pin 4 and the inner diameter of the aperture part outer cylinder 9 and the piece 1
3 A perfect circular slit 14 with a constant width is provided between the inner surface and the inner surface.
is beginning to form.

A ring 15 is provided on the outer periphery of the throttle outer cylinder 9, and an actuator 16 is attached to the ring 15. Actuator 16 is part of piece 1
3 (left and right pieces 13 in FIG. 2), and some of the pieces 13 can be slid along the groove 12 to bring them closer to or away from the flow pin 4. There is. actuator 1
The other pieces 13 (the upper and lower pieces 13 in FIG. 2) which are not connected to the diaphragm 6 are fixed to the diaphragm outer cylinder 9. The direction of the radial groove 12 can be changed as shown in FIG. 4 by changing the tightening of the mounting screw 17 to the head body 1 for assembling the throttle outer cylinder 9 to the lower side of the head body 1. It is becoming possible to do this.

The molten resin sent into the head body 1 from the molten resin inlet 2 shown in FIG. It is extruded from the exit slit 18 in the form of a parison.

During extrusion of the parison, when the piece 13 on the right side in Figure 2 is slid in the direction away from the flow pin 4, the slit 14 in this area becomes wider, the flow distribution of the molten resin increases in this area, and the elastic strain also increases. In this way, a parison 19 is formed which is thick only on the right side as shown in FIG. When piece 13 is returned to its original position, a parison with uniform thickness will be obtained.

In the case of the arrangement shown in Figure 4, the upper right and lower right pieces 1
3 in a direction away from the flow pin 4, a parison 20 with thicker walls at the upper right and lower right sides is formed as shown in FIG.

By moving the piece 13 closer to or away from the flow pin 4 in this way, thick-walled portions can be created at required positions in the circumferential direction and length direction of the molded product. Furthermore, by sliding the piece 13 gradually from the beginning to the end of extruding the parison, it is possible to create a wall thickness that varies over the entire length of the parison.

In the embodiments shown in FIGS. 2 and 4, the pieces 13 are arranged in four places and the actuators 16 are in two pieces, but these numbers can be increased or decreased as desired. Moreover, if the aperture part outer cylinder 9 is allowed to rotate freely during extrusion of the molded product, a parison having a spiral thick wall part can be produced. In the blow head, not only the accumulator head but also
It can also be applied to cross type, spider type, and extrusion heads.

〔Effect of the invention〕

The present invention has the effect that the wall thickness of any part of the parison can be changed by sliding the piece along the groove using an actuator, and there is no need for special machining of the nozzle.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, Fig. 2 is a cross-sectional view taken from - in Fig. 1, Fig. 3 A and B are cross-sectional views of a parison molded as shown in Fig. 2, and Fig. 4 The figure is a sectional view similar to FIG. 2 of another embodiment of the present invention, FIG. 5 is a sectional view of a parison molded as shown in FIG. 4, and FIG. 7th
The figures are a cross-sectional view taken from FIG. 6, FIG. 8 is a cross-sectional view taken from FIG. 6, and FIG. 9 is a cross-sectional view similar to FIG. 7 of the conventional device. In the figure, 1 is the head body, 4 is the flow pin, 8,
14 is a slit, 9 is an outer cylinder of the throttle part, 12 is a groove, 1
3 represents a piece, and 16 represents an actuator.

Claims (1)

[Claims] 1. A flow pin provided in the head body, a slit formed between the head body and the outer periphery of the flow pin, and a slit built in the head body and formed between the outer periphery of the flow pin, and a radial shape centered on the flow pin. A throttle part outer cylinder having a groove, a piece fitted into the groove of the throttle part outer cylinder, and an actuator that slides the piece along the groove to approach or move away from the flow pin. A blow molding head characterized by: