JPS5934492B2 - Continuous molding method and device for plastic square tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and an apparatus for continuously molding a rectangular tube such as a rectangular container from a long plastic sheet.

These days, the bodies of square plastic containers that are widely used as simple packaging containers are individually molded from a single plastic sheet that has been cut to a predetermined size. Since most of the manufacturing process was done manually, not only was productivity low, but the precision of the product was also extremely low.

In view of these circumstances, the present invention first mechanically forms a long thermoplastic plastic sheet fed at a constant speed into a cylindrical shape, and then introduces the cylinder into a prismatic mandrel and heats it to form corners. By molding, the rectangular cylinders can be continuously molded, thereby solving the problems described above.

Hereinafter, the configuration of the present invention will be described in more detail based on one embodiment. In the figure, 1 is a cylindrical molding device, in which a long plastic sheet is continuously fed at a constant speed via a feed roller 2, etc. For the purpose of winding S into a cylindrical shape, for example, a large number of forming rollers 3a and a cylindrical mandrel 3 are used.
It consists of a bending part 3 consisting of a bending part 3, etc., and a bonding machine 4 connected to the tip of the bending part 3. ' can be sequentially joined by heat or glue, etc., so that a predetermined cylinder T can be obtained continuously.

Reference numeral 5 is a prismatic mandrel having an outer circumferential length that is approximately the same as the inner circumferential length of the cylinder T, the middle part of which is a heater zone 5a having a structure as shown in FIG. 2, and the tip end thereof having a certain taper. The introduction part 5b is a plane, and the latter half thereof is a cooling zone 5c, and 6 is a guide plate or a guide roller provided close to each outer surface of the heater zone 5a in the prismatic mandrel 5. This is the information department.

In FIG. 2, 7 is a heater embedded in each corner of the prismatic mandrel 5 via a heat insulating material 8, and 9 is a Teflon film constituting the outer peripheral surface of the mandrel including each heater 7 at the corner. show.

Therefore, the present invention sequentially feeds the plastic sheet S into the cylindrical forming device 1 to continuously form a predetermined cylinder T, and then feeds the cylinder T into the prismatic mandrel 5 via the introduction part 5b. The circumferential surface of the cylinder T is deformed along the outer shape of the prismatic mandrel 5, and at the same time, the corners of the sheet that soften while passing through each corner heated by the heater 7 are bent. Since the tube is cooled in the cooling zone 5c, the tube is sequentially fed by the feed roller 25 and passed through the prismatic mandrel 5, so that a predetermined prismatic tube B can be obtained continuously.

Therefore, by cutting these rectangular tubes B to a desired length using a separate cutter (not shown), it is possible to immediately form the body of the rectangular container.

In addition, in the process of forming the rectangular tube B of the present invention, the guide portion 6 such as the guide roll provided in the heater zone 5a of the rectangular column mandrel 5 presses each surface of the rectangular tube B passing through this portion against the mandrel. It has the function of removing distortion of the sheet and forming the rectangular tube better.

The rectangular cylinder B obtained by the present invention is not limited to the rectangular shape shown in the figure, but can be formed into any other polygonal, semicircular, fan-shaped, crescent-shaped, etc. shape by changing the shape of the mandrel. A rectangular tube of the form is obtained.

In summary, according to the method and apparatus of the present invention, the body of a square plastic container, which conventionally required a great deal of effort, can be continuously molded with much higher productivity and precision than a long sheet. It has a special effect.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of the device of the present invention, and FIG.
FIG. 3 is a cross-sectional view of the heater zone in the figure. In addition, in the figure 1... Cylindrical molding device, 2, 2'...
...Feed roller 3...Bending part, 4...
...Gluing machine, 5...Prismatic mandrel, 6...
...Information section, 7...Heater.

Claims (1)

[Scope of Claims] 1. A plastic made by winding a long thermoplastic plastic sheet fed at a constant speed into a cylindrical shape, gluing the overlapping parts, and shaping the cylinder into a rectangular cylinder shape. In the continuous forming method of a square cylinder, the cylinder is fitted onto a square cylinder mandrel through an introduction part, each corner of the cylinder is heated and shaped, and the outer periphery is pressed by a guide part to form a square cylinder shape. A continuous molding method for plastic square tubes. 2 A series of rectangular plastic cylinders that is equipped with a cylinder molding device that molds a long plastic sheet into a cylinder shape that is continuously fed at a constant speed, thereby shaping the molded cylinders into a rectangular cylinder shape. A molding device comprising: a prismatic mandrel having a pressure guiding portion on the outer periphery and a heater embedded in each corner; and a prismatic mandrel connected to the cylindrical molding device via an introduction portion. Continuous molding equipment.