JPH0420011Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a parison wall thickness control device in a blow molding machine.

[Prior Art] In order to make the wall thickness of a blow-molded product uniform, an axial wall thickness control device for a parison has conventionally been used.

[Problems to be solved by the invention] However, in order to make the wall thickness of the molded product ideal, it is necessary to locally control the wall thickness in the circumferential direction of the parison. However, it was not possible to reliably control the wall thickness of a portion of a molded product without any problems.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention was developed to provide a wall thickness adjusting device that can reliably control the wall thickness locally in the circumferential direction of the parison without any hindrance. ,
In a blow molding machine that injection-forms a parison from a slit formed between a mandrel disposed at the center of the lower end of the parison head body and a die provided on the outer periphery of the mandrel, a part of the slit surface of the die is formed by injection molding. At least one arcuate groove is provided in a required range, and a pair of arcuate wall thickness adjustment segments are provided in the groove so as to be rotatable by a pin. A rod of a pushing device is connected to the pusher by penetrating the die from one side, and further extends to the lower surface of the die, circumferentially covering the lower part of the arcuate wall thickness adjustment segment and the lower part of the slit surface of the die, and connecting the rod with the mandrel. This invention relates to a wall thickness control device for a parison in a blow molding machine, characterized in that a fixed nozzle is constructed by attaching an annular plate that forms a slit continuous with the slit.

[Function] Partial wall thickness control of the parison is performed by the wall thickness adjustment segment provided in the middle of the slit formed by the die and mandrel, and the fixed nozzle located downstream of the wall thickness adjustment segment controls the thickness of the parison. The flow velocity is corrected to be uniform and the shape of the outer peripheral surface is finished smoothly.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

Figure 1 shows a parison head in a blow molding machine. 1 is the head body, 2 is a die provided at the lower end of the head body, and 3 is a die provided at the center of the die 2, and a parison 4 is inserted between the die 2 and the parison head. A mandrel for forming the slit 5 to be injected, 6 a rod for raising and lowering the mandrel 3 to adjust the thickness of the slit 5, 7 a piston for injecting the parison 4, and 8 an injection cylinder.

In such a parison head, as shown in FIGS. 2 and 3, an arcuate groove 9 is partially provided in the circumferential direction in the middle of the slit 5 surface of the die 2, and a slit is inserted into the groove 9. Adjustment segments 10 and 11 are provided for adjusting the 5-distance interval.

The details of the adjustment segments 10, 11 are as shown in FIG. That is, the segments 10 and 11 have a substantially symmetrical arc shape, and the outer end portion 10 of each segment is substantially symmetrical.
a and 11a are formed into curved shapes and are slidably fitted into both ends of the groove 9, and bracket portions 10b and 11b are protruded from the inner ends of the stepped pins 12 to accommodate the small diameter of the stepped pin 12. The parison 4 is pivotally connected in a telescopic manner at the slit 5 side, and is configured to be able to bulge outward around the pin 12 due to the injection pressure of the parison 4 from the slit 5 side. Furthermore, a rod 14 of a push device 13 for pressing the segments 10 and 11 toward the slit 5 is slidably connected to the outer surface of the large diameter portion of the pin 12 through a pin 15 passing through the die 2.

Note that the lower end of the die 2 functions as a fixed nozzle 16, and the fixed nozzle 16 has adjustment segments 10 and 11 provided at the lower end of the die 2, and the adjustment segments 10 and 11 have a lower end. It may also be formed by attaching the ring plate 17 to.

If it is desired to partially increase the thickness of the parison 4 ejected from the slit 5, this is done by shrinking the rod 14 of the pusher 13 by the required amount. That is, when the rod 14 is retracted, since the rod 14 and the pin 12 are slidably connected by the pin 15, only the rod 14 moves to the right in FIG. When the parison 4 is ejected from the slit 5 in this state, the segments 10 and 11 move to bulge to the position of the imaginary line due to the pressure, and stop when the pin 12 abuts against the rod 14. As a result, the distance between the slits 5 is increased in the segments 10 and 11, and the thickness of the parison 4 to be injected can therefore be increased. In this case, segment 1
0 and 11 move so as to bulge outward, a slight gap is formed between their outer ends 10a and 11a and both ends of the groove 9 in the die 2, and when the parison 4 is extruded in this state, the parison Since an axial protrusion is formed on the outer wall of the die 2, in the present invention, the die 2 is designed to completely cover this gap superficially.
A fixed nozzle 16 is provided at the lower part of the parison 4, and the fixed nozzle 16 scrapes off the protrusions formed from the gap, thereby finishing the outer wall of the parison 4 smoothly.

In addition, the temperature of the area where the adjusting segments 10 and 11 are provided is low and the temperature distribution in the circumferential direction is different from that of the die 2, so the flow of the parison 4 tends to be uneven. Due to the presence of fixed nozzles 16 with uniform temperature distribution, non-uniformity in the flow of the parison 4 is corrected.

Furthermore, the fixed nozzle 16 is connected to the adjustment segment 1.
It is thought that by being located downstream of the adjustment segments 10 and 11, the effect of increasing the partial thickness of the parison 4 by the adjustment segments 10 and 11 is reduced.
The parison 4, whose wall thickness has been partially increased by the adjustment segments 10 and 11, passes through the fixed nozzle 16 and is once narrowed down, but after passing through, the wall thickness returns to some extent and becomes thick again, so there is almost no problem. do not have. Since the adjustment segments 10 and 11 are provided in the middle of the slit 5, it is possible to have a larger stroke than when provided at the lowest end of the slit 5. Therefore, by controlling the wall thickness to be thicker in advance, the length of the fixed nozzle 16 can be increased. Equalizing effects can be addressed.

On the other hand, in order to make the thickness of the parison 4 uniform in the circumferential direction from the above state, simply press the pusher 13.
All you need to do is to extend the rod 14 to a predetermined position.
As a result, the segments 10 and 11 return to the positions indicated by solid lines in FIG. 2, and the intervals between the slits 5 become uniform in the circumferential direction. At this time, segments 10 and 11
The parison 4 that has entered the gap between the outer ends 10a, 11a of the groove 9 and both ends of the groove 9 is automatically pushed out from this gap.

Incidentally, in the above embodiment, the segments 10,
11 is provided at only one place in the circumferential direction of the die 2, the number can be arbitrarily selected, the pin 12 and the rod 14 may be fixed together, and any push device 13 can be used. Of course, various other changes may be made without departing from the gist of the present invention.

[Effects of the invention] As described above, according to the invention, the thickness of the parison can be partially adjusted in the circumferential direction by the adjustment segment provided at the lower end of the die, and the adjustment segment is located downstream of the die. However, the fixed nozzle part that extends circumferentially to cover the lower part of the arc-shaped wall thickness adjustment segment and the lower part of the slit surface of the die can equalize the flow velocity of the parison, so the wall thickness of the molded product can be made ideal. Furthermore, the fixed nozzle portion provides an excellent effect in that the outer circumferential surface of the parison can be smoothly finished.

[Brief explanation of the drawing]

Fig. 1 is a schematic cutaway side view of a parison head equipped with the wall thickness control device of the present invention, Fig. 2 is an enlarged view in the - direction of Fig. 1, and Fig. 3 is an enlarged view in the - direction of Fig. 1. , FIG. 4 is an explanatory diagram of the adjustment segment. 2 is die, 3 is mandrel, 5 is slit, 9
is a concave groove, 10 and 11 are segments, 10a and 11
a is the outer end, 12 is the pin, 13 is the push device,
16 indicates a fixed nozzle.

Claims (1)

[Scope of utility model registration request] In a blow molding machine that injection-forms a parison from a slit formed between a mandrel disposed at the center of the lower end of the parison head body and a die provided on the outer periphery of the mandrel, a part of the slit surface of the die is formed by injection molding. At least one arcuate groove is provided in the required range, and within the groove,
a pair of arc-shaped wall thickness adjustment segments are arranged so as to be rotatable by pins, and a rod of a pushing device is connected to the pins by penetrating the die from the outside of the die;
Furthermore, by attaching an annular plate to the lower surface of the die, the ring plate extends circumferentially to cover the lower part of the arcuate wall thickness adjustment segment and the lower part of the slit surface of the die, and forms a slit that is continuous with the slit between the mandrel and the mandrel. A parison wall thickness control device for a blow molding machine, characterized by comprising a fixed nozzle.