JPH02248211A - Control device of diameter of parison - Google Patents

Abstract

PURPOSE:To obtain a molding which is free from generation of flashes and possesses a uniform thickness, by a method wherein resin is extruded, a die and core of a head forming a parison running along a blow molding tool are controlled through a movement and the diameter of the parison is made variable. CONSTITUTION:Resin 3 is extruded through an extruding machine, passed through a space between a die 4 and core 5 and extruded. A thickness and form of the resin 3 to be extruded are varied through opening and closing of the die 4 and core 5 and an up-and-down movement of a rod 8 constituting an accumulator head 7. This variation control is performed by a parison controller 9. Since the variation in diameter of the parison is possible by making the die and core variable like this, generation of flashes and blow moldings having a nonuniform thickness can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a parison diameter control device, for example, a parison diameter control device for a parison for blow molding.

[Prior Art] Conventionally, apparatuses for blow molding plastic molded products have been disclosed, for example, in Japanese Utility Model Application Publication No. 62-111833. For example, when manufacturing a resin gasoline tank, a parison 2 of a certain shape is molded using a mold 1 as shown, and the parison 2 is inserted into the mold 1 to make a molded product for blowing. I'm trying to get it.

[Problems to be Solved by the Invention] However, in the conventional method for obtaining a blow-molded product, the part corresponding to the convex part of the tank body is pressed with a mold, and the part A of the parison 2 with a large expansion ratio is The thickness becomes thinner. At the same time, as shown in the sectional view of the tank in FIG. 14, burrs B are formed on the upper and lower portions of the tank body 17 and burrs C are formed on the recessed portions. For large molded products such as resin gasoline tanks, the diameter of the parison needs to be larger than the width of the mold in order to achieve a uniform thickness, but this creates the problem of a large amount of parison. .

In addition, Fig. 15 shows the relationship between the parison shape direction and thickness, and when molded into the drum shape shown in Fig. 15 (a), the upper and lower parts have a thinner flesh layer as shown in Fig. 15 (b). , the center becomes thicker. That is, there is a problem that the meat layer becomes non-uniform.

Therefore, the parison diameter control device of the present invention has been made in view of the above problems, and its purpose is to:
It is an object of the present invention to provide a parison diameter control device that can produce a parison necessary to obtain a molded product made of a resin without forming any flakes or the like and having a uniform flesh layer.

[Means and effects for solving the problem] In order to solve the above-mentioned problems and achieve the object, the parison diameter control device of the present invention has a head that forms a parison along a resin extrusion and blow molding die. A means for controlling the movement of the die and core constituting the head is provided to vary the diameter of the parison.

Preferably, the diameter of the parison is varied in a device that extrudes the resin and forms a parison along the blow-molded product, which is a pre-process for obtaining a resin molded product with a uniform flesh layer. .

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

FIG. 1 is an overall system diagram of a parison diameter control device according to a first embodiment. Moreover, FIG. 2 is a sectional view of a main part showing a blow molded product obtained by the blow molding die shown in FIG. Both figures show how a drum-shaped resin molded product 2 is molded with a uniform flesh layer using a blow mold 1.1', but in order to obtain such a resin molded product 2, Before blow molding, it is necessary to make a parison that fits the main mold. To explain the method of manufacturing a parison having such a shape, in FIG. 1, resin 3 is extruded from an extruder (not shown) and when passed between die 4 and core 5, Extrusion pressure is applied to the resin 3 by the hydraulic mechanism 6, and the resin is extracted.

In order to vary the thickness and shape of the resin 3 extracted at this time as shown in the figure, the die 4 and core 5 constituting the accumulator head 7 are opened and closed, and the rod 8 is moved up and down as shown by the arrows. By doing so, I am trying to change things. This change control is performed by the parison controller 9.
It's something you should do accordingly. For example, if the position of the die 4 and the piece 5 of the parison controller 9 is set to +10, the rod 8 is hydraulically moved up and down by the hydraulic unit 10 so that the diameter is the maximum, and the die 4 and the piece 5 are moved back and forth by operating the hydraulic cylinder 11. to open/close.

In this way, the diameter of the extruded parison 18 can be changed.

As a result, the parison extruded into a shape that conforms to the blow mold is molded by the mold 1.1'.

FIG. 3 is a sectional view showing the second embodiment. Further, FIG. 4 is a detailed view of FIG. 3. In FIGS. 3 and 4, an elastic body 12, such as rubber, is disposed near the lower end of the die 4. As shown in FIGS. The oil tank 14 is pressurized by the hydraulic cylinder 11 via the accumulator 13, and the elastic body 12
By expanding the resin in the circumferential direction and changing the relationship between the die 4 and the piece 5, the extrusion pressure of the resin 3, that is, the diameter of the parison 18 can be changed. In addition, the purpose can be achieved not only by hydraulic adjustment but also by pneumatic adjustment. Furthermore, the third
By moving the piece 5 up and down in the direction of the arrow shown in the figure, it is also possible to arbitrarily adjust the gap between the die and the piece to create an irregularly shaped parison.

With this configuration, even if the cross-sectional view of the parison is elliptical, it can be easily manufactured without problems with the joints because an elastic body is used. Additionally, since it can be controlled by hydraulic pressure, fine adjustments can be made continuously. Furthermore, by using fluorine-based rubber or resin on the surface of the elastic body 12, the problem of friction with the resin can be solved.

Next, FIGS. 5 to 8 are sectional views showing a third embodiment of the present invention. Of these, FIG. 5 is a cross-sectional view showing the shape of the die and the core, and there are a plurality of flaps 1 near the lower end of the die 4.
5 is arranged. This flap (feather)
is supported by a coil spring or an elastic body, and can be moved by external force. Therefore, when extruding the resin, the degree of opening and closing of the flap is changed by changing the resin pressure.

This allows the parison diameter to be made variable. Furthermore, FIG. 6 is a sectional view showing the flap opening/closing mechanism in detail. Moreover, FIGS. 7 and 8 are cross-sectional views showing the operating state of the flap, and in the case of FIG. 7, the core 4 is lowered in order to uniformize the parison thickness by operating when the parison diameter is large. It is used in the same condition.

FIG. 8 shows the operating state when the parison diameter is small, and shows the clip 15 in a state where the coil spring 16 acts thickly. In this way, the clip uses the elastic body of the coil spring, and the diameter of the parison can be continuously adjusted using only the resin pressure without the need for a separate driving source.

Note that, as in the above embodiment, even when the cross-sectional shape of the parison is elliptical, there is no problem with the joints and the parison can be easily manufactured. That is, by opening and closing the flap on the goo side, an irregularly shaped parison can be formed. Further, since the die is circular, the flaps can be attached as shown in FIG. 6 to prevent resin leakage between the flaps.

9 to 12 are cross-sectional views showing a fourth embodiment of the present invention. That is, as shown in FIG. 9, the die 4 has an elliptical shape and is movable in the longitudinal direction by a hydraulic cylinder 1i. The core 5 is also elliptical, so that the cross-sectional shape in the major axis direction and the minor axis direction can be gradually changed. That is, the die is moved in the longitudinal direction using a hydraulic or pneumatic cylinder, and at the same time the core 5 is moved in the vertical direction, thereby making it possible to vary the diameter of the parison.

Furthermore, FIG. 10 is a cross section taken along line AA' in FIG.
Figure 1 is a cross section taken along line BB' in Figure 9.

Further, FIG. 12 is a diagram showing the operating state of the die shown in FIG. 9, in which the extensible portion of the die is configured to be slidable by a hydraulic cylinder 11. Such a configuration requires only a part of the conventional equipment to be modified, and moreover, it is possible to provide equipment that can continuously vary the parison diameter with relatively high reliability.

[Effects of the Invention] As described above, in the present invention, by changing the die and core, it is possible to change the parison diameter, which eliminates the occurrence of parison and uneven wall thickness in conventional blow molding. The aim is to completely eliminate the problems that frequently occurred with blow molded products, and to provide products with extremely uniform wall thickness and no flaking.

[Brief explanation of drawings]

Fig. 1 is an overall system diagram of the first embodiment, Fig. 2 is a sectional view showing a blow molded product, Figs. 3 and 4 are sectional views showing the second embodiment, and Figs.
FIG. 8 is a sectional view showing the third embodiment, FIGS. 9 to 12 are sectional views showing the fourth embodiment, and FIGS. 13 to 15 are explanatory diagrams showing the prior art. 1.1'...Blow mold, 2...Resin molded product, 3.
...Resin, 4...Gui, 5...Core, 6...Hydraulic mechanism, 7...Accumulator head, 8...Rod, 9...Parison controller 10...Hydraulic unit, DESCRIPTION OF SYMBOLS 11... Hydraulic cylinder 12... Elastic body, 13... Accumulator 14... Oil tank, 15... Clip, 16... Coil spring, 17...
...tank body, 18... parison. Figure 6 Figure 7 Figure 8 Figure 9 Figure 12 (A) 0 units) Figure 15

Claims (4)

[Claims] (1) A head for extruding resin to form a parison along a blow molding die, characterized by being provided with movement control means for moving the die and core that make up the head, thereby making the diameter of the parison variable. parison diameter control device. (2) A head that extrudes resin to form a parison along the blow molding die, and has an elastic body near the bottom end of the die and moves the core up and down to arbitrarily adjust the gap between the die and the core. 2. The parison diameter control device according to claim 1, wherein the parison diameter control device is capable of controlling a parison diameter. (3) A head that extrudes resin to form a parison along the blow molding die, and has multiple flaps near the bottom end of the die that are directed by elastic bodies such as coil springs, and moves the core up and down to connect to the die. 2. The parison diameter control device according to claim 1, wherein the gap between the cores can be arbitrarily adjusted. (4) A head that extrudes resin to form a parison along the blow mold.The die is elliptical and movable in the major axis direction, and the core is also elliptical, and the major axis and minor axes are movable. 2. The parison diameter control device according to claim 1, wherein the parison diameter control device is capable of arbitrarily adjusting the gap between the die and the core by moving it in the vertical direction to gradually change the cross-sectional shape in the direction.