JPH0822569B2 - Extrusion molding method and soft molding - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an extrusion molding method for molding a curved long product using a thermoplastic resin, and a curved soft molding as a mold material molded using this method.

[Prior art]

Conventionally, the extrusion molding method has been used to mold a thermoplastic resin into a rod shape or a tubular shape, or to mold it as a mold material having a uniform cross-sectional shape in the longitudinal direction. This mold material is used for various purposes, but it may be used as a soft molding for attaching to a thin metal plate, for example, by sandwiching its edge with a forked attachment portion.

[Problems to be Solved by the Invention]

By the way, a long product molded by an extrusion molding method is generally linear, and it is very difficult to mold it as a curved product. Therefore, when attaching a straight molding to a curved part such as the edge of a disk-shaped member, the inner peripheral length and outer peripheral length of the molding do not match There was a deviation from the surface of the member. Therefore, there is a defect that the appearance after mounting is poor and the molding easily comes off. Therefore, the technical problem to be solved by the present invention is to allow a flexible elongated molding to be preliminarily provided with a bending tendency along the shape of the edge of a member to be attached by enabling the formation of a curved long product in an extrusion molding method. is there.

[Means, actions and effects for solving the problems]

The extrusion molding method according to the present invention is configured as follows in order to solve the above technical problems. That is, it consists of a step of extruding a heat-melted thermoplastic resin from a die, a step of cooling the resin extruded from the die along the circumference of the drum, and a step of winding the cooled resin, and the die in the extrusion step. The resin extruded from is shaped as a mold material with a hollow cross section and a substantial wall thickness that is constant or gradually decreases from one side to the other side. It is characterized in that the substantial wall thickness (dimension in the width direction of the drum) is set to be constant or gradually reduced from the outside to the outside. In this method, the resin extruded from the die is cooled while curving around the drum, so that a product having a bending tendency in advance can be obtained as a product. Also,
In the extrusion molding method, the cross-sectional shape as a mold material can be variously set, but if the substantial wall thickness of the resin is set to be constant or gradually reduced outward in the radial direction of the drum in this way, The outer peripheral side is more likely to be curved, and a good product can be obtained. Further, since the resin has a hollow cross-sectional shape, sink marks or the like are less likely to occur during molding, so that the quality of the product is further improved.
In addition, if the hollow portion is provided, the resin thickness is set to be gradually reduced outward in the radial direction of the drum even if the outer side of the curve is wider outwardly. Since it is easy, the degree of freedom of the outer shape of the obtained mold material is increased. Then, according to this extrusion molding method, a curved soft molding made of a thermoplastic resin, having a bifurcated attachment portion inside the curve and a hollow decorative portion outside the curve, from the inside of the curve It is possible to obtain a soft molding that is set such that the substantial wall thickness of the resin is uniform or gradually decreases toward the outside. Since the soft molding molded by this method has been given a bending tendency in advance, even when it is attached to the edge of a disc-shaped member, the outer peripheral side part may be displaced from the surface of the attached member. , The mounting part does not come off easily.

【Example】

The extrusion molding method according to one embodiment of the present invention shown in FIGS. 1 to 4 will be described in detail below. FIG. 1 shows a part of a manufacturing line for molding a molding for filling a gap between a periphery of a wheel cap of an automobile and a tire. A gap is provided between the wheel cap and the tire to prevent the wheel cap from falling off or being damaged by the deformation when the tire is punctured and deformed.
The reason why the molding is attached to that part is that there is a problem in terms of design and air resistance if there is a gap. Also, since the wheel cap should not come off when the tire is punctured due to the addition of the molding, the molding should be easily deformed, and conversely, the molding should not vibrate due to wind pressure during normal running of the car. Therefore, there must be some rigidity. In the figure, reference numeral 1 denotes a die, and a raw material resin supplied to an extruder (not shown) is extruded through the die 1 to be molded as a molding 2 having a desired sectional shape. In the conventional extrusion molding method, the extruded molding 2 is pulled straight in the water tank by the take-up machine to be cooled, but in this method, the drum 4 having an appropriate diameter is provided in the water tank 3. And the drum 2 from the molding 2 through the roll 5
Cooling is performed while pulling along with a predetermined speed. As shown in FIG. 2 which is a sectional view taken along line II-II of FIG.
The drum 4 includes side walls 4a and 4b and a protrusion 4c located therebetween.
And are used as sizing portions for regulating the cross-sectional shape. As shown in the drawing, the molding 2 is a mounting portion 2a formed in a bifurcated manner so as to sandwich the edge of the wheel cap.
And a decorative portion 2b that is connected to the mounting portion 2a, and is extruded from the die 1. A hollow portion 2c is formed in the decorative portion 2b. And this mall 2
The substantial thickness of the resin forming the is set so as to decrease toward the outside in the radial direction of the drum 4.
By setting the cross-sectional shape of the molding 2 in this way,
The occurrence of sink marks during cooling is suppressed and the surface becomes smooth. Further, since the side walls 4a and 4b are located on the sides of the molding 2, the outer peripheral edge of the molding 2 is prevented from being displaced from the surface of the drum 4 during cooling. FIG. 3 shows a state in which the molding 2 molded by this method is mounted on the wheel cap 8 of an automobile. In the figure, 6 is a wheel and 7 is a tire. If this molding 2 is used, its outer peripheral portion does not shift from the side surface of the wheel cap 8, so that problems such as deterioration of appearance do not occur. Further, the molding is generally required to have the contradictory performance that it must be easily deformed when the tire is punctured as described above, and must not vibrate due to wind pressure during normal running. In the molded mall 2, when the tire 7 is punctured and deformed as shown by the phantom line in FIG. 4 by forming the decorative portion 2b in a hollow shape, compared with a solid one having the same outer shape. Since it is easily deformed, it is possible to reliably prevent the wheel cap 8 from falling off or being damaged without transmitting the deformation of the tire 7 to the wheel cap 8. At the same time, the decorative portion 2b has a closed structure and has a certain degree of rigidity. Therefore, it does not vibrate due to wind pressure during normal traveling.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a part of a production line for carrying out an extrusion molding method according to an embodiment of the present invention, and FIG. 2 shows II of FIG.
-II line enlarged sectional view, FIG. 3 is a sectional view of an essential part in a state in which a molding molded by this method is mounted on a wheel cap of an automobile, and FIG. 4 is an enlarged sectional view of a mounting portion of this molding. 1 ... Die, 2 ... Resin molding, 2a ... Mounting part, 2b ...
… Decoration part, 2c …… hollow part, 3 …… water tank, 4 …… drum,
4a, 4b ... Side wall, 4c ... Projection, 5 ... Roll, 6 ...
Wheel, 7 ... Tire, 8 ... Wheel cap

Claims (2)

[Claims] 1. A die (1) for heating and melting a thermoplastic resin.
And a step of cooling the resin (2) extruded from the die (1) along the circumference of the drum (4), and a step of winding the cooled resin (2). In the extrusion step, the resin (2) extruded from the die (1) is shaped as a mold material having a hollow cross section and a substantial wall thickness that is constant or gradually reduced from one side to the other side, and in the cooling step, the drum ( The extrusion molding method is characterized in that the resin along 4) is set in a direction in which the substantial wall thickness is constant or gradually decreases from the inside in the radial direction of the drum (4) to the outside. 2. A curved soft molding made of a thermoplastic resin (2), which has a bifurcated mounting portion (2a) on the inside of the curve and a hollow decorative portion (2b) on the outside of the curve.
A soft molding characterized in that the substantial wall thickness of the resin is set to be constant or gradually reduced from the inside to the outside of the curve.