JPS5850176B2 - How to make plastic containers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing plastic containers, particularly blow molded plastic containers having an outwardly facing flange at the mouth.

When this type of container is used for food packaging, in order to prevent foreign matter from entering the container between forming and filling, or to prevent bacteria from propagating within the container,
As shown in Fig. 1, a cylindrical bulge having the same diameter as the desired flange a is provided at the tip of the mouth, and the air blow hole during blow molding is closed to seal it, and this is placed immediately before filling. Means is taken to cut the opening at a desired location, for example, along the line A--A.

However, since the above-mentioned opening was conventionally cut by machining using a cutting blade C, the shape of the flange end face after cutting was likely to be inclined as shown in A and H in FIG.
The incidence of defects due to so-called "diagonal cuts" was high.

This is due to the fact that the container is an elastic body made of plastic and that it is difficult to fix the cut portion.

On the other hand, the above problem can be solved by rotating the cutting blade C relatively along the cutting surface, but rotating the cutting blade or the container is more difficult than fixing the container and the manufacturing cost is high. Become.

The present invention has been made in consideration of the above-mentioned problems, and is designed to make the opening of the plastic container perpendicular to the axis, without generating cutting waste, and to make the cut edges smooth. It is an object of the present invention to provide a method for manufacturing a plastic container that can be cut.

The embodiment will be described below based on the embodiment shown in FIG. 3 and below.

In the figure, 1 is a plastic container, and 2 is its mouth.This part has an annular bulge having a substantially V-shaped cross section in the direction perpendicular to the axis. A protruding portion 3 and a cylindrical head portion 4 disposed on the distal side of the protruding portion 3 are blow molded.

The tip portion 3a of the annular bulge 3 is thinner than the base portion due to the nature of blow molding.

Then, the heating plate 5 is brought into contact with the circumferential outer surface of the annular bulging portion 4 of the mouth portion 2 formed as described above.

As shown in FIG. 4, the heating plate 5 has a ring shape and is disposed so as to be freely movable in the axial direction. It is formed into a widened tapered shape.

In addition, as shown in FIG. 6, this heating plate 5' is divided into a plurality of parts so that it can be expanded and contracted in the axial angle direction of the mouth part 2, and when it is contracted, it surrounds the annular bulge part 4 and the tip part of this part is expanded and contracted. It may be made to abut on the outer circumferential surface of.

Note that FIG. 6 shows a case where the shapes of the mouth and the cylindrical head are different from those of the above embodiment.

When the heating plates 5, 5' come into contact with the circumferential outer surface of the annular bulge 3, this portion melts and the cylindrical heads 4, 4' are instantly separated by the annular bulge 3, forming the openings 2, 7. A plastic container 1,1' is obtained which has an outwardly directed flange 6.6'.

Note that the thermal cutting in the above embodiment is not limited to simply bringing the heating plate 5° 5' into contact with the outer circumferential surface of the tip 3a of the annular bulging portion 3, but may also be carried out by blowing flame or heated gas. It's okay.

Furthermore, if the heating and fusing is carried out in a state where the annular bulging portion 3 is pressed in the axial direction and tension is applied to the outer circumferential surface of the bent tip, the fusing time can be shortened.

As described above, the present invention manufactures a plastic container in which the head part is sealed and blow molded, and then the head part is cut in a direction perpendicular to the axis to form a mouth part having an outward flange. In method 1, during the blow molding, an annular bulge 3 having a substantially V-shaped cross section and approximately the same diameter as the outward flange is formed on the outside of the head 4, and its tip 3a is After that, the entire outer circumferential surface of the tip 3a of the annular bulge 3 is heated and this part is heated and melted. After blow-molding a plastic container that has an outward flange, the mouth is formed so that the flange shape of the mouth is perpendicular to the axis and the cut edge is smooth. Moreover, it can be cut in an extremely short time.

Further, according to the present invention, the mouth can be formed in one step of heating the entire outer circumferential surface of the tip 3a of the annular bulge 3, and the mouth can be formed using plastic having an outward flange at the mouth. Post-processing required for forming the mouth portion after blow molding the container can be extremely reduced.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing a plastic container made by the conventional method, FIGS. 2A and B are enlarged cross-sectional views of main parts showing defective cutting conditions made by the conventional method, and FIG. 3 is a partially cutaway front view showing a plastic container made by the conventional method. FIG. 4 is a partially cutaway front view showing the head being cut off, FIG. 5 is a partially cutaway front view showing the state after cutting, and FIG. 6 is a partially cutaway front view showing the other side of the plastic container with a different shape. FIG. 3 is a partially cutaway front view showing a state in which the head is cut off. 1 is a plastic container, 3 is an annular bulge, 4 is a cylindrical head, and 5 is a heating plate.

Claims (1)

[Claims] 1. A method for manufacturing a plastic container in which the head is sealed and blow molded, and then the head is cut in a direction perpendicular to the axis to form a mouth having an outward flange, during the blow molding, On the outside of the head 4, an annular bulge 3 having a substantially V-shaped cross section and approximately the same diameter as the outward flange is bulge-molded with its tip 3a being thinner than other parts, and then A method for manufacturing a plastic container, characterized in that the entire outer circumferential surface of the tip 3a of the annular bulge 3 is heated so that this portion is cut by heating.