JPS6049582B2 - Paper cup curl forming method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper cup curl forming method and apparatus for forming a curl on the mouth edge of a paper cup, and particularly to a paper cup curl forming method and apparatus for forming a curl on the mouth edge of a rectangular paper cup whose side wall has a small taper. The present invention relates to a paper cup curling method and apparatus suitable for use in the present invention.

Generally, in molding a paper cup, a storage recess 2 is formed in a mold body 1 as shown in FIG. 1, and a paper cup 3 is inserted into this storage recess 2.

The storage recess 2 is closed by an auxiliary mold 4, and the curl forming surface 1a of the mouth edge of the storage recess 2 cooperates with the curl molding surface 4a formed on the lower surface of the auxiliary mold 4. A curled portion 3a is formed at the edge of the paper cup 3. In molding such a paper cup, if the paper cup to be molded is a circular paper cup 5 as shown in FIG. Therefore, buckling does not occur in the side wall 5a at all.

However, in the square paper cup 6 as shown in FIG. 3, the force is concentrated on the corner 6a of the curled portion, so that the side wall corner portion 6b may buckle, resulting in poor molding.

Therefore, as shown in FIG. 4, a presser mold 7 is provided so as to be movable up and down through the auxiliary mold 4, and the side wall 6c of the cup 6 is pressed into the storage recess 2 with the inclined pressing surface 7a of the presser mold 7. By pressing against the side wall 2a, buckling of the side wall corner portion 6b is prevented.

However, when the taper angle θ of the side wall of the cup 6 is large, the corner portion 6 of the side wall is
Although the occurrence of buckling in b can be effectively prevented, when the taper angle θ becomes small (when the side wall of the cup becomes almost vertical), it is not possible to sufficiently suppress the occurrence of buckling.

This is due to the following reasons: FIGS. 5A and 5B show that the buckling suppressing force varies depending on the taper angle of the cup side wall 6c, and FIG. b is the case where the taper angle is θ2 (θ1>θ2). Now, if the descending forces of the presser die 7 are F and F, this descending force F can be divided into component forces Fla and Flb perpendicular to the side wall 2a of the storage recess 2 and component forces F2a+F2b parallel to the side wall 2a. . The component forces Fla and Flb act as suppressing forces that suppress buckling, and the component forces F2a and F2b act as buckling promoting forces that promote buckling. Here, because of the relationship θ2 × θ1, the component force Flb<Fla, and the cup side wall 6c
As the taper angle becomes smaller, the buckling suppressing force becomes smaller and buckling becomes more likely to occur. In addition, in order to increase the buckling suppressing force, it is sufficient to increase the descending force F, but as F increases, the buckling promoting force also increases, and it is not necessary to apply an excessively large descending force F. If the presser mold 7 slips and the cup side wall 6
It will cause damage to c.

In view of the above, the present invention provides curl forming of a paper cup that allows curling to be formed at the cut-off edge without causing buckling at the corner of the side wall even in a rectangular paper cup with a relatively small taper of the cup side wall. An object of the present invention is to provide a method and apparatus.

Hereinafter, one aspect of the present invention will be explained with reference to FIGS. 6 to 9. An example will be explained.

Note that the same parts as in FIG. 4 are given the same reference numerals.

In FIG. 6, an opening 4a is provided in the center of the auxiliary mold 4, and a cylindrical support member is inserted into the opening 4a. A shaft 10 passes through the support shaft 10 so as to be slidable up and down, and two support disks 11 and 12 are attached to the lower end of the support shaft 10 with an interval in between the support disks 11 and 12. The split presser mold 13 is housed so as to be slidable in the horizontal direction (direction perpendicular to the axis of the housing recess 2).

As shown in FIG. 8, the divided presser mold 13 is composed of four divided pieces 13a of the same shape, and the upper surface of the center side corner of the divided presser mold 13 of each divided piece 13a is notched in an arc shape, and from the upper surface. An inclined surface 13b is formed toward the lower surface.

A lower wedge portion 14a of the operating shaft 14, which is slidably housed within the support shaft 10, is engaged with these four inclined surfaces 13b. A guide hole 13c is formed along the diagonal line in a portion of each divided piece 13a located on a diagonal line of the divided presser mold 13, and the support disks 11 and 12 are connected within this guide hole 13c. A connecting portion 15 is inserted. A recess 13e is formed in the vertical middle of the holding surface 13d facing the side wall 2a of the four divided pieces 13a, and a presser spring 16 is housed in this 13e. The divided pieces 13a are pressed so that the entire divided presser mold 13 is reduced.

Next, the effect will be explained.

First, an intermediate product m (FIG. 6) made by pasting developed blanks into a cylindrical shape is inserted into the storage recess 2 of the mold body, and then the support shaft 10 is lowered to move the split presser mold 13 into the storage recess 2a. Install it at the specified location inside.

Next, by pushing down the operating shaft 14 by appropriate means, each divided piece 13a is pushed outward. Therefore, the holding surface 13d of each divided piece 13a firmly presses the side wall of the intermediate product m onto the side wall 2a of the storage recess. Thereafter, the auxiliary mold 4 is lowered to form a curled portion 6d at the upper end of the intermediate product m (FIG. 7). Note that by pressing down the operating shaft 14, each divided piece 13a
moves outward along the diagonal line of the entire divided presser die, and at this time, each divided piece 13a moves smoothly due to the engagement between the connecting portion 15 and the guide hole 13c. When all of the above steps are completed, the auxiliary mold 4 is moved upward and the support shaft 10 is lifted upward.

Then, due to the action of the presser spring 16, each divided piece 13 contracts toward the center of the presser die and returns to its original position. after that,
Take out the curled square paper cup. Said divided piece 1
The force relationship acting on the paper cup when the paper cup 3a presses the side wall 6c of the paper cup onto the side wall 2a of the storage recess is as shown in FIG.

Now, if the force (applied in the horizontal direction) applied to the side wall 6c of the paper cup by the dividing piece 13a is f, this force f is divided into a force component force f1 in a direction perpendicular to the side wall 2a and a force component force f1 along the side wall 2a. It is divided into an upward component force F2.

The component force f1 acts as a force that presses the paper cup against the side wall 2a, and the component force F2 acts as a buckling suppressing force that prevents the paper cup from buckling. In this way, if the paper cup is held down by the horizontal force of the dividing piece 13a without pressing down the paper cup on the side wall 2a by the descending force of the presser mold, the buckling promoting force as in the conventional method will not exist, and the splitting Even if the force for pushing the pieces 13a apart is small, a sufficient buckling suppressing force can be generated. Since the present invention is configured as described above, when forming a paper cup, the paper cup has a shape such as a square in which the force of the auxiliary mold during forming is concentrated on a part of the side wall, and the side wall tapers. Even if the corner is small and nearly vertical, it is possible to efficiently form a curled portion at the edge of the mouth without buckling the side wall.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view of a conventional circular paper cup forming device, Figure 2
The figure is a perspective view of a circular paper cup, Figure 3 is a perspective view of a square paper cup, Figure 4 is a vertical cross-sectional view of a conventional square paper cup forming device, and Figure 5a is the force exerted by the presser die when the taper angle of the paper cup side wall is large. Figure 5b is an explanatory diagram of the force relationship by the presser die when the taper angle of the paper cup side wall is small, Figure 6 is a longitudinal sectional view of the curl forming device according to the present invention, and Figure 7 is the operation of the split presser die. FIG. 8 is a longitudinal cross-sectional view of the curl forming device according to the present invention, FIG. 8 is a cross-sectional view taken along the line ■-■ in FIG. 7, and FIG. 9 is an explanatory diagram of the force relationship applied by the divided pieces. 1... Mold body, 2... Storage recess, 4... Auxiliary mold, 6... Square paper cup, 10... Support shaft, 11,
12...Support disc, 13...Divided presser mold, 13a...
・Divided piece, 14... Operating shaft, 16... Push.

Claims (1)

[Scope of Claims] 1. Insert the paper cup assembled by winding the developed blank into the paper cup storage recess formed in the mold main body, move the auxiliary mold toward and away from the mold main body, and close the storage recess opening of the mold main body. In the paper cup curl forming method, which forms a curled part on the mouth edge of the paper cup in cooperation with the edge, after inserting the paper cup into the storage recess, a divided presser mold consisting of a plurality of divided pieces is placed inside the paper cup. and moving each divided piece of the divided presser mold outward in a direction perpendicular to the axis of the storage recess so as to expand the entire divided presser mold within the paper cup, and press the paper cup side wall against the storage recess side wall, A method for curling a paper cup, characterized in that the auxiliary mold is then brought into contact with the mouth edge of the storage recess of the mold body to form a curled portion on the mouth edge of the paper cup. 2. A mold body equipped with a storage recess for receiving a paper cup, an auxiliary mold that is in contact with and separated from the mold body and cooperates with the mouth edge of the storage recess to form a curl on the mouth edge of the paper cup, and a It has a presser die which is inserted into the stored paper cup and presses the side wall of the paper cup against the sidewall of the storage space, and the presser die includes a plurality of divided pieces and each of these divided pieces is connected to the axis of the storage recess. A paper cup curling device comprising an operating member movable in orthogonal directions.