JPS6257494B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of molding a cup or other container by heating and softening a synthetic resin sheet, and using a male mold and a female mold by vacuum forming, pressure forming, or a combination of both. This is related to the improvement of.

In conventional thermoforming of synthetic resin sheets, that is, sheet molding, as shown in Fig. 1, a resin sheet n' is clamped onto the upper surface of a female mold 1' having a desired shape, and this is heated at a predetermined temperature. After softening, the male mold 2' was pushed into the female mold and the resin sheet was pressed to obtain a molded product.

However, in this molding method, as shown in the enlarged view of FIG. The corner periphery 1'a of the female mold 1' is not sufficiently press-filled. As a result, the bottom outer peripheral edge 5' of the container n after molding is formed between the bottom wall surface 3 and the side wall surface 4.
Since the synthetic resin does not intersect linearly to form an edge angle, and the synthetic resin shrinks on cooling, it is formed into a round arc shape in cross section. Although this does not occur when injection molding is used, it often occurs in sheet molding, especially when containers are molded from foamed resin sheets such as expanded polystyrene.

The biggest drawback of the bottom outer peripheral edge 5' of the containers being rounded is that when the containers n are inserted one after another and stacked in a stacker of an automatic filling device as shown in Figure 3, the outside of the bottom of the inserted containers n is The peripheral edge 5' does not accurately abut the locking step 6 provided on the inner surface of the lower container n into which it is inserted, and as shown in the enlarged view of FIG. It's easy to get caught up in it.

In this state, the container and the other containers following it are tilted with respect to their normal positions in the stacker, so the spacing (a) between the opening peripheries 7 of container n becomes unequal, and the guidance for container delivery becomes uneven. This prevents the normal operation of the claws, etc., and causes problems such as the inability to feed containers.

In addition to the above-mentioned container shape, the same drawback is that, as shown in FIG. Even when stacked containers are molded in contact with the opening periphery 10 of the lower container n, the same problem occurs because the lower outer periphery 9 is rounded.

In order to eliminate the above-mentioned drawbacks of the conventional container, the present invention aims to eliminate the need for the outer peripheral edge of the required lower surface of the container to have an arcuate cross-sectional shape, and instead the lower surface and the peripheral wall surface to intersect linearly and form an angular shape. The present invention provides a molding method that can be formed.

In order to achieve the above object, the present invention provides a method for pressure-molding a synthetic resin sheet, which is heated and softened by pushing a male mold into a female mold, into a container of a predetermined shape. Separate the female mold part from the female mold body to make it a movable mold that moves up and down, and always keep the outer peripheral edge of the molding surface of the movable mold adjacent to the lower end peripheral edge of the peripheral wall molding surface of the female mold at the same height. ,
The male mold is pushed into the female mold, and the synthetic resin sheet is pressed, and the movable mold is moved slightly upward, and the softened synthetic resin on the lower surface is pressurized, and the lower end of the peripheral wall molding surface of the female mold is pressed. It is characterized in that it is press-fitted into the periphery of the corner, and the outer periphery of the lower surface of the container is formed into a ridge.

In the present invention, the desired lower surface of the container is the lower surface that comes into contact with the locking part of the lower container when a large number of containers are inserted in order and stacked, and specifically, the lower surface of the bottom wall mentioned above. , and the lower surface of the enlarged diameter opening, the outer peripheral edges of which are formed into a ridge angle.

Figures 5 to 7 show an example in which the outer peripheral edge of the bottom of a container is formed into a ridge shape by the molding method of the present invention, and the present invention will be described below with reference to the drawings of this example. .

As shown in FIGS. 5 and 6, the female mold 1 used in the present invention has a bottom wall molding surface 3a with a side wall molding surface 4a.
The movable mold 12 is separated from a main body having a main body and connected to an air cylinder or the like (not shown) to move up and down. As shown in FIG. 5, in this movable mold 12, the outer peripheral edge of the bottom wall molding surface 3a is always placed adjacent to the lower end peripheral edge of the side wall molding surface 4a at the same height position, and the entire female mold 1 is In this part, a corner edge 1a similar to the conventional one is formed. Also, male type 2
has the same structure as the conventional one, but its bottom wall molding surface is made slightly higher in relation to the female mold 1, and the softening resin sheet on the bottom wall becomes slightly thicker when pressurized. .

In this manufacturing method, the resin sheet n' is clamped on the upper surface of the female mold 1 as in the conventional method, heated and softened at a predetermined temperature, and the male mold 2 is pushed into the female mold 1 to form the resin sheet n'. Pressure is applied to form the entire container.
In this case, the portion of the resin sheet n' corresponding to the bottom outer periphery 5 of the container is not completely press-fitted into the corner periphery 1a of the female mold 1, as shown in FIG. ing.

Next, while maintaining this pressurized state, as shown in FIG. 7, when the movable mold 12 of the female mold 1 is moved upward in the direction of the male mold with a slight stroke, the thick softened resin on the bottom wall portion is pressurized. The annular corner edge 1a
It is pushed in and filled without any gaps. For this reason, the roundness of the bottom outer peripheral edge 5 disappears, and an angular line is formed at the boundary between both surfaces by the bottom wall molding surface 3a and the side wall molding surface 4a, which intersect linearly.

After this molding is completed, the male mold 2, the pressure mold 12
is returned to its original position, the molded container n is taken out by a conventional method, and burrs and the like formed on the outer peripheral edge 5 of the bottom part are removed.

FIG. 11 shows an example in which the present molding method was applied to the outer peripheral edge 9 of the lower surface of the enlarged diameter opening 8 of the container n. In this case, the lower molding surface 9a of the female mold 1 is separated to form a movable mold 12, and the molding method thereof is the same as in the example described above.

FIGS. 8 to 10 show the case where containers obtained by this molding method are sequentially inserted and stacked, and the required outer peripheral edge 5 of the bottom of container n,
Since the outer peripheral edge 9 of the lower surface is not rounded but formed at a ridge, the end surface of this lower surface reliably abuts against the upper surface of the locking step 6 and the opening peripheral edge 10 of the lower container n, and one side thereof slides in. I can't get into it any deeper. For this reason, the distance between the opening edges 7 and 10 of the container is
(a) is always kept constant, and the supply and delivery of the container by the guide needle etc. can be performed reliably, smoothly and stably.

As described above, according to the molding method of the present invention, the part of the female mold that molds the desired lower surface of the container is separated to form a movable mold, and a heat-softened resin sheet is pressure-molded by the male mold. In a pressurized state, the movable mold presses the softened resin into the corner periphery of the female mold, so that the outer periphery of the lower surface of the container can be formed into a ridged corner. This has the effect that even the outer periphery of the container can be reliably formed into an angular shape using a sheet.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional sheet molding die, Fig. 2 is a sectional view of its main parts, Fig. 3 is a partial sectional view of a stacked state of a conventional container, and Fig. 4 is a sectional view of its main parts. An enlarged cross-sectional view, Figure 5 is a cross-sectional view of the mold of this molding method,
FIG. 6 is a partial sectional view taken along the line A-A in FIG. Figure 9 is an enlarged sectional view of the main part, Figure 10 is a sectional view of a stacked state of containers of other shapes made by this molding method, and Figure 1
FIG. 1 is a sectional view for explaining the method of forming the container shown in FIG. 10. 1...female type, 1a...corner periphery, 2...male type,
5...Bottom outer periphery, 9...Bottom outer periphery, 12...
Movable type, n'...resin sheet, n...container.

Claims (1)

[Claims] 1 In a method of press-molding a synthetic resin sheet, which is heated and softened by pushing a male mold into a female mold, into a container of a predetermined shape, the part of the female mold that forms the desired lower surface of the container is separated from the female mold body. The mold is made into a movable mold that moves up and down by the movable mold, and the outer peripheral edge of the molding surface of the movable mold is always kept at the same height adjacent to the lower end peripheral edge of the peripheral wall molding surface of the female mold, and the male mold is pushed into the female mold. Then, with the synthetic resin sheet under pressure, the movable mold is moved slightly upward, and the softened synthetic resin on the lower surface is pressurized and press-fitted into the corner edge of the lower end of the peripheral wall molding surface of the female mold, and the lower surface of the container is pressed. A method for molding a synthetic resin sheet molded container, characterized in that the outer peripheral edge of the container is formed into a ridged edge.