JPS62122733A - Preparation of plastic parts for trim of automobile - Google Patents

Abstract

PURPOSE:To prepare a plastic part covered with a fabric in a simple process by placing the fabric between the mold surface of a hollow mold and a parison, by pinching the excess parts of the parison and the fabric on the parting line and by cutting off the excess part of the parison and the excess part of fabrics adhered thereon. CONSTITUTION:A fabric 14 is placed between a molten parison 12 and the mold surface of a hollow mold 10 and the hollow mold is thereafter closed to pinch the excess parts of the parison and the fabric by the pinch-off part of the parting line. The parison 12 is expanded outside by blowing air and tightly adhered on the mold surface either through the fabric at the area where the fabric exists or directly at the area where no fabric exists to become a molten thermoplastic plastic layer 20 having a shape of the mold surface. The molten thermoplastic plastic and the fabric 14 become unitarily on the parting line 22. As the burr part has higher rigidity than the plastic alone, it can be easily cut off by means of knife and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing plastic parts for automobile interiors.

(Prior Art) Plastic products are often used for automobile interior parts due to their light weight and ease of molding. Among these, plastic products, such as console box lids, require a certain degree of thickness. It is said that a plastic hollow body is preferable from the viewpoint of achieving further weight reduction.

Conventionally, such a plastic hollow body is made of a cylindrical body called a parison made of thermoplastic plastic in a heated and molten state, or two sheets of sheet parison are sandwiched between blow molds, and air is injected into the parison. Blow into it,
It is manufactured by the so-called blow molding method, in which the parison is inflated and brought into close contact with the mold surface to form the shape of the mold surface.

By the way, due to the recent trend toward higher quality vehicle interior parts, those whose surfaces are covered with fabric to improve softness and decorativeness have come to be preferred. Therefore, the hollow body obtained by the previous blow molding is covered with a fabric in a post-processing process to form an interior part.

(Problems to be Solved by the Invention) However, the subsequent processing consists of adhesive application work, fabric covering work, etc., which complicates the manufacturing work and increases the overall number of man-hours. .

The present invention aims to solve the above problem and provides a method for manufacturing fabric-covered plastic parts with simple operations.

(Means for Solving the Problems) This invention involves sandwiching a parison made of thermoplastic plastic in a heated and molten state between hollow molds, and blowing air into the parison to inflate the parison and bring it into close contact with the mold surface. , in a method for manufacturing plastic parts with a mold surface shape, a fabric is placed between the mold surface of a hollow mold and a parison, the excess parison and excess fabric are sandwiched at a parting line, and the molding process is performed. After that, the excess fabric portion stuck to the excess parison is removed.

Further, it is preferable that the hollow mold is configured such that the pinch-off portion on the fabric side is located further inward than the pinch-off portion on the other side at the parting line.

(Function) The heated and molten parison expands in the direction of the mold surface of the hollow mold by blowing air. Then, the mold surface shape is formed through the fabric in the areas where the fabric is present and by directly contacting the mold surface in the areas without the fabric. At this time, since the parison is in a molten state, it is welded to the back surface of the fabric or penetrates into the weave or line of the fabric to become integrated with the fabric. and,
The subsequent cooling hardens the molten thermoplastic that formed the parison and fixes it in the shape of the mold surface. After demolding, the thermoplastic and fabric integrated product is deburred and made into a desired automobile interior plastic part.

The paris is formed by sandwiching a molten surplus parison and surplus fabric at the parting line of a blow molding die, and is an integral part of the thermoplastic plastic and the fabric. Therefore, Paris has more rigidity than fabric alone, and because of its rigidity, it does not twist or wrap when being cut with a knife or the like, making it easier to cut out. Furthermore, by providing the pinch-off portion of the parting line of the hollow mold at the inner end thereof, the base of the paring portion can be made thinner, making it easier to remove the paring portion.

In addition, the hollow mold is placed at its parting line,
If the pinch-offs on one side of the fabric are more inward than the pinch-offs on the other side, the resulting plastic part will have a fabric edge surface that is the same as the surface of the exposed thermoplastic plastic part that follows the edge. Or, it is located at a position deeper than the surface, making it difficult for the edges of the fabric to peel off during assembly and use.

(Example) The present invention will be explained below based on Examples.

FIGS. 1 and 2 are cross-sectional views showing the process of manufacturing a plastic part in an embodiment of the present invention.

In the figure, 10 is a hollow mold, 12 is a parison, and 14 is a fabric.

The hollow mold IO consists of a split mold, and the inner surface thereof is provided with a cavity having the outer shape of the desired plastic part, and the parting line surrounding the cavity is provided with a protruding edge-shaped pinch-off portion. Further, an air blowing port is provided at a predetermined position on the parting line.

The parison 12 is formed into a cylindrical shape by extruding thermoplastic plastic such as polypropylene or hard vinyl chloride resin from an extruder 16. Note that, instead of this cylindrical parison 12, two sheet parisons made of thermoplastic plastic may be used as appropriate.

This parison 12 is heated and molten between the mold surfaces of the hollow molds 10 and 10.

The fabric 14 enhances the decorativeness and soft feel of the surface of the plastic parts, and can be made of various materials, but one with high extensibility is preferred.

This fabric 14 is transferred to the fabric 1 in the molten state.
2 and the mold surface of the hollow mold 10, the hollow mold is closed, and air is blown into the parison 12 by an air blowing nozzle 18 to perform so-called blow molding.

Incidentally, when closing the mold, the parison and the excess portion of the fabric are pinched at the pinch-off portion of the parting line.

The blowing of air causes the parison 12 within the mold to bulge outward. The molten thermoplastic plastic layer 20 forms a mold surface shape through the fabric in the areas where the fabric 14 is present, and directly on the mold surface in the areas without the fabric. At this time, the molten thermoplastic layer 20 adheres to the back side of the fabric 14 or penetrates into the weave of the fabric 14 and is integrally bonded to the fabric 14. Also, the parting line 22 of the hollow mold
In this case, the molten surplus parison 12 and the surplus fabric 14 are sandwiched together as described above, so that the molten thermoplastic plastic and the fabric 14 are integrated. This part is commonly known as Paris.

Then, by subsequent cooling, the molten thermoplastic is hardened to form an integral body of thermoplastic and fabric fixed in the shape of the mold surface, and the integral body is demolded and the above-mentioned pars removal is performed. As a result, the plastic part shown in FIG. 3 is obtained. 24 indicates a thermoplastic part.

As described above, the snap portion is made of an integral piece of fabric and thermoplastic, and has more rigidity than fabric alone, so it can be easily cut out with a knife or the like. By making the so-called pinch-off portions 10a, 10a at the inner end of the parting line of the hollow mold 10 into an edge shape as shown in FIG. 4, the thickness of the root of the pari is reduced, making it easier to remove the pari. becomes.

FIG. 5 is a sectional view of a main part of a plastic part obtained in another example. As shown in FIG. 6, this plastic part is manufactured using a hollow mold 10, with the pinch-off part 11a on the fabric side being slightly inward than the pinch-off part 11b on the other side at the parting line, in other words, from the center of the mold surface. It was constructed as described above and manufactured as described above. As a result, this plastic part is constructed such that the surface of the fabric end 14a is the same as or one of the surfaces of the thermoplastic exposed portion 14b that follows that end 14a.
Since the position is recessed from the surface of the fabric 4b, the fabric end 14a is less likely to be caught during assembly or use, reducing the risk of it turning outward and peeling off.

(Effects of the Invention) This invention produces a plastic part in which the fabric and thermoplastic plastic are integrated by placing a fabric between the parison and the mold surface of a blow mold and performing blow molding. . Therefore, according to the present invention, when a parison or the like is blow-molded into a plastic part shape, the surface can be covered with fabric at the same time without performing post-processing as in the past, and the manufacturing work is greatly reduced compared to the past. It is simplified as follows.

In addition, since Paris is a combination of fabric and thermoplastic, it is more rigid than fabric alone, and can be easily removed because it does not twist or wrap when cut with a knife, etc. It becomes possible. Furthermore, by forming the pinch-off portion of the hollow mold into an edge shape, the root of the pari can be made thinner, making it even easier to remove the pari.

Furthermore, by configuring the hollow mold so that the pinch-off part on the fabric side is located more inward than the other pinch-off part, it is possible to make it difficult to peel off the fabric end on the surface of the resulting plastic part.

[Brief explanation of drawings]

The drawings relate to embodiments of the invention, and FIGS. 1 and 2 are cross-sectional views showing the process of manufacturing plastic parts, FIG. 3 is a cross-sectional view of the plastic parts, and FIG. 4 shows a hollow mold for facilitating the removal of pars. FIG. 5 is a cross-sectional view of a main part of a plastic part in which peeling of the fabric is prevented, and FIG. 6 is a cross-sectional view of a main part showing a hollow mold for obtaining the previous plastic part.

Claims (2)

[Claims] (1) A method for manufacturing plastic parts in which a parison made of thermoplastic plastic in a heated molten state is sandwiched between hollow molds, air is blown into the parison, the parison is inflated and brought into close contact with the mold surface, and the mold surface shape is obtained. , Place fabric between the mold surface of the hollow mold and the parison, sandwich the excess parison and excess fabric at the parting line, and cut off the surplus fabric that is stuck to the excess parison after molding. A method for manufacturing plastic parts for automobile interiors, characterized by: (2) The method for manufacturing plastic parts for automobile interiors according to claim 1, wherein the pinch-off portion on the fabric side is located inside the pinch-off portion on the other side at the parting line of the blow mold.