JPS61230921A - Plastic bending process and its device - Google Patents

Abstract

PURPOSE:To enable die cost to be out and mass production to be performed continuously by molding a plastic resin between rolls while it is soft. CONSTITUTION:A synthetic resin material is thermally softened and the soften resin is continuously extruded from the dies 12 of an intrusion molder B by the required amount for each product and in the form of a prearranged cross section. This extruded material is fed into between a main molding roll which rotates at a speed synchronized to the feed speed and the second molding roll 5, 6 at the drain side of the main molding roll. An adjusting handle 8', 8' is slackened and the molding roll 5, 6 is separated from the main molding roll. Then the main molding roll and the molding roll 5, 6 are replaced respectively to enable different products to be produced. The intermediate product molded is cut by the operation of a cutter 10 and allowed to assume a stable form through cooling in a cooling tank 9. Thus many processing steps, precision dies and molding conditions requiring skill are no longer required.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method and apparatus for bending plastics made from thermoplastic synthetic resin and having any arbitrary curved shape, such as mudguards for bicycles, children's cars, etc. Regarding.

Conventionally, in order to form mudguards for bicycles, children's cars, etc., a thin metal plate was previously punched out using a press to a size roughly commensurate with the finished product, and then this was drawn and formed using multiple forming rolls. Regardless of the roll, the punched metal plate is used in a drawing die using another press, and is divided into several stages depending on the degree of deformation (depth of drawing, degree of bending), and is gradually brought closer to the shape of the finished product. A processing method was used.

Then, it was finished by polishing with a separate cloth, plating, or painting.

Therefore, the above method utilizes the plasticity of a thin metal sheet to form it, but there are many steps required to complete it, and the drawing depth and shape vary, requiring a burning process. In addition, there is a drawback that the product cannot be completed without going through a bending process.Furthermore, since the base metal is usually an easily available iron plate, it is necessary to apply anti-corrosion treatment.

Therefore, such roll and press molded products are often molded using synthetic resin because they require a large number of steps and are expensive in terms of labor and mold fees. The raw material is heated and softened and then injected into a mold using an extruder under high pressure, thereby molding the product in a shape that follows the mold all at once.

Therefore, with synthetic resin, the number of steps is fewer than when metal is rolled or press-formed, and there is no need for anti-corrosion treatment such as plating or painting, and productivity is much better than when using rolls or press-forming. On the other hand, when using synthetic resin molding, the production cost of the molding mold is high, and in addition, skill is required to maintain the mold and maintain the molding conditions.

<Problems to be Solved by the Invention> The present invention addresses the above-mentioned drawbacks of the conventional processing methods, and provides a processing method and its equipment that do not require many steps, precision molds, or molding conditions that require skill. The purpose is to provide the following information.

<Means for Solving the Problems> The present invention consists of a main molding roll that rotates at a constant speed, a main molding roll that rotates at a constant speed, and a first and second molding roll that rolls in opposition to the main molding roll, which rolls a thermoplastic synthetic resin raw material supplied in a softened state. After passing between both rolls, it is cut and rapidly cooled.

<Function> By pressurizing the softened synthetic resin extruded from the extrusion rock with the main molding roll and the first molding roll while it is still sufficiently plastic, the cross-sectional shape in the direction of travel is made into a predetermined shape, Furthermore, a curved shape is formed by the mold surface of the main forming roll and the 27th &-shaped roll, and the product is stabilized by cutting it to a required length and quickly cooling it without deformation.

<Examples> Hereinafter, the processing method and apparatus of the present invention will be explained in detail with reference to examples shown in the drawings.

First, the bending apparatus A shown in FIGS. 1 and 2 has a main forming roll 1 horizontally supported on a machine frame 2 by a sleeve 3, and a pulley 4 fitted on one end of the shaft 3 and an electric motor 19i11. A regulating band is provided between the output shaft end of the main forming roll 1 and the pulley at the end of the output shaft, and the main forming roll 1 is rotated at a constant speed via the controlling band by driving the electric motor 11. On the outer circumferential surface, that is, on the mold surface, a first molding roll 5 that defines the cross-sectional shape in the traveling direction and a second molding roll 6 that is curved in the traveling direction are circumscribed. A second forming roll 6 for forming a curve in the direction is rotatably pivoted by a pongee 7 to an adjusting device 8 mounted on the machine frame 2, and by rotating an adjusting handle 81 of the adjusting device 8, 1. The contact pressure between the second forming roll and the main forming roll 1 is adjusted.

A cutting device 10 (an air set operated by a solenoid valve or any other device may be used) is disposed on the concentric axis of the main forming roll 1 and facing the outer peripheral surface of the main forming roll 1.

), and the cutting device moves along the circumference of the main forming roll 1 at a synchronous speed only during the cutting operation, and returns to the initial position at the same time as the cutting is completed. I am trying to repeat it within a fixed range of .

Further, the main forming roll 1 has its substantially lower half submerged in a cold water tank 9 placed on the side surface of the machine frame 2, and the water in the cold water tank 9 is supplied to a cooler (not shown). It is made to circulate continuously through the process. Incidentally, in the above, a pre-cooling device of a shower set may be provided between the 27th & mold roll and the cutting device to prevent deformation during cutting.

Then, on the side of the bending device A configured as described above, an extruder IIB for heating and softening the synthetic resin raw material and extruding the material a is installed, and from the die 12 attached to the extrusion opening. The material a is continuously extruded in the amount required for each product and in a predetermined cross-sectional shape. In the main forming roll 1 and the first . It is supplied between the second forming rolls 5 and 6 and is formed when moving from the first forming roll 5 to the next second forming roll 6. Then, the mold surface of the main molding roll 1 and the first molding roll 1 are connected to each other.
The shapes of the mold surfaces of the second molding rolls 5 and 6 generally differ depending on the shape of each product, but in this case,
Loosen the adjustment handles 8' and 8° and adjust the 1st. The second forming rolls are separated from the main forming roll, respectively, and the main forming rolls (large and small) and the first forming roll are separated from each other. Different products can be obtained by changing the attachment of the second forming rolls 5 and 6, respectively.

As an example, as shown in FIGS. 3(1) and 3(2), a convex portion 1 with a semicircular cross-sectional shape. a main forming roll 1 having a shape and a first forming roll 1 having a semicircular recess 51; A product is formed by the second forming roll 5.6, and the main forming roll 1 has a trapezoidal convex portion 12 in cross-section and the first forming roll 1 has a flat-bottomed concave portion 52.
A product b2 is formed with the second forming rolls 5 and 6, and as shown in FIG. The intermediate product thus formed further moves together with the main molding roll 1 and is cut by the operation of a cutting device 10 that operates at every predetermined rotation angle of the main molding roll 1. It is immersed in water and cools down to stabilize its shape.

Furthermore, although one example of the bending device has been shown above, as shown in FIG. , a movable type 1. having a semicircular or other arbitrary curved shape is placed on the chain band 14 stretched across the sprocket wheel 13.13. ．． 1
．． . . . are arranged at equal intervals, and a forming roll 5 circumscribing the movable die is disposed opposite to the movable die at the upward folded end of the chain band 14 by a moving mechanism 15.

The material a extruded from the die 12 of the extrusion IB may be supplied between the forming roll 5 and a movable die in contact therewith. In this case as well, the softened material supplied between the movable die 11 and the forming roll 5 is connected to the movable die which moves in the direction of the arrow;
It is pressure-formed into a predetermined cross-sectional shape with the forming roll 5, is located in the middle of the circulation path of the chain band 14, moves at a speed synchronized with the chain band 14 only during the cutting operation, and returns at the same time as the cutting is completed. A stable product can be obtained by providing a cutting device that operates intermittently, disconnecting from the supply side, and dropping and immersing the product into the cold water tank 9 located below.

In addition, in the above two embodiments, a cold water tank was used as a means for cooling the product, but this pond cold water may be sprayed as a shower, or cold air may be sprayed. Therefore, there is no need for a large water tank, and especially when a chain belt circulation system is used as in the latter embodiment, it is effective without taking up much space.

<Effects of the Invention> The processing method and apparatus of the present invention are as described above, and break down the conventional fixed concept that molding is possible only by enclosing the material in an airtight mold. Since the molding is performed between rolls, there is no need for elaborate and complicated plastic molding molds, so the number of molds can be greatly reduced.

In addition, it can be continuously molded, has good workability, and is suitable for mass production. Moreover, since the configuration is simple, maintenance and management are significantly easier than previous ones.

Furthermore, unlike the conventional method of drawing metal using a press, such as mudguards for bicycles and children's errands, the number of processes is small, the production cost is low, and the main forming roll and two forming rolls are easy to manufacture. It has many excellent effects, such as being able to obtain various products other than the products shown in the example, which have different cross-sectional shapes and curved shapes, just by doing this.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of the processing apparatus of the present invention, Fig. 2 is a sectional view taken along the line XX in Fig. 1, and Fig. 3 <1) and (2) show the different cross-sectional shapes of forming rolls. FIG. 4 is a front view showing an example of a mudguard, and FIG. 5 is a partially cutaway front view showing an example of a pond device.

Claims (1)

[Claims] 1. A continuously supplied softened plastic material having approximately the cross-sectional shape of a product is formed into a predetermined bent shape before hardening, then cut into a specified length, and immediately cooled. A plastic bending method characterized by: 2. A main forming roll that rotates at a constant speed, and at least two forming rolls that roll in circumscribed contact with the mold surface of the main forming roll;
It consists of a cutting device installed opposite to the circumferential side of the main forming roll and a cooling device for cooling the molded product, and between the main forming roll and the forming roll, the softened material extruded from the die of the extrusion device is placed between the main forming roll and the forming roll. 1. A plastic bending apparatus, characterized in that a plastic material is guided and shaped by the rolls while uncured, then cut and immediately cooled. 3. The plastic bending apparatus according to claim 2, characterized in that the main forming rolls having a curved surface shape are constituted by a movable type in which a plurality of main forming rolls are arranged at equal intervals on an endless band. 4. The plastic bending apparatus according to claim 2, characterized in that a cold water tank is used as the cooling device. 5. The plastic bending apparatus according to claim 2, wherein a cold water or cold air injection device is used as the cooling device.