JPS5930537B2 - Manufacturing method for painted molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a molded product with a beautiful end portion.

Conventionally, as described in Japanese Patent Publication No. 50-28975, a sheet with patterns, letters, etc. is molded onto a synthetic resin molded product by molding a sheet with a pattern, letters, etc. on the uneven surface of a mold and/or A method of preforming the sheet by vacuum or pressure forming so that it can fit into a curved surface, etc., and then attaching the sheet to a mold and vacuum suction, and Japanese Patent Publication No. 50-19132
As described in the above issue, after vacuum forming the painted sheet using a female mold for injection molding, using the sheet and mold as they are, placing a male mold for injection molding on the opposite side and injecting. A method of molding is known.

However, these methods have the following drawbacks.

That is, as shown in FIG.
Since the corner radius of the sheet is smaller than the corner radius of the parting part of the mold (illustrated as the corner radius of the stationary mold 1 in Fig. 1), the sheet is placed in the injection mold. When the sheet is installed and mold-clamped and held by the parting surface extending along the end surface of the cavity 3, the position of the end of the sheet tends to shift, and when the synthetic resin is press-fitted into the cavity 3, the end of the cavity Wrinkles may occur on the surface of the sheet, significantly damaging the appearance of the molded product.

Figure 2 shows a cross-section of a molded product molded with decoration using this method, with unnecessary edges of the sheet removed at the end. This results in further deterioration of the appearance of the product.

In order to solve these shortcomings, the
It is also possible to trim the preformed sheet into a predetermined molded product shape before installing it in the mold in method No. 5, but since it is necessary to cut a part of the side or corner of the three-dimensional sheet, There still remain problems such as automation using a punching press etc. being difficult and time consuming, and the precision of the trimming position being poor (missing portions of the sheet form at the ends of the molded product, spoiling the aesthetics).

The present inventors have arrived at the present invention as a result of intensive research into a method for obtaining a molded product with a beautiful end portion without wrinkles on the surface of the product.

That is, the present invention provides a method for decoratively molding a sheet having patterns, letters, etc. preformed into a shape having an uneven surface and/or a curved surface, in which all or part of the edges of the preformed sheet are placed in a cavity. A method for manufacturing a painted molded product, characterized in that the molded product is held by a parting surface of a stationary mold, a movable mold, or a slide core extending along the side wall.
And in the above manufacturing method, it is held not only by the parting surface of the stationary mold, the movable mold, or the slide core extending along the side wall of the cavity, but also by the parting surface that intersects with these parting surfaces. The present invention relates to a method for manufacturing a painted molded product characterized by holding the molded product.

To further explain the present invention in detail, the sheets used in the present invention include all thermoplastic synthetic resin sheets, films, or at least one layer made of these thermoplastic synthetic resins used in normal vacuum or pressure forming. Laminated sheets can be used.

Examples of these sheets include sheets of polyvinyl chloride and vinyl chloride copolymers, styrenic polymers such as polystyrene and ABS resins, polyolefins such as polyethylene and polypropylene, nylon, acrylic resins, etc., or laminates thereof. Alternatively, it is used after being preformed by pressure forming to have a desired uneven surface or curved surface.

The sheet may be preformed by conventional vacuum or pressure forming, or by a combination of these methods.

In addition, as a preforming method, it is possible to use the
It is also possible to use a female mold for injection molding.

The synthetic resins that are press-fitted into the mold cavity with the above-mentioned preformed sheet include all thermoplastic synthetic resins commonly used in injection molding, such as polyvinyl chloride and vinyl chloride copolymers, polystyrene, etc. Also used are styrene polymers such as ABS resins, polyolefins such as polyethylene and polypropylene, nylon, acrylic resins, blends thereof, or products in which foaming agents, glass fibers, fillers, etc. are added to these.

The combination of the above-mentioned sheet used in the present invention and the synthetic resin to be press-fitted is selected in consideration of the adhesive properties of both and the performance required of the product.

In the present invention, when the preformed sheet is mounted on a mold, there is no problem in using known techniques such as static electricity, vacuum suction, adhesive, etc. in combination.

Furthermore, the edges of the preformed sheet that are held by the parting surface of the stationary mold, movable mold, or slide core that extends along the side wall of the cavity do not necessarily need to be held in their entirety. It is also possible to retain only a portion of the molded product as long as it does not adversely affect the appearance of the molded product.

The usual injection molding method is used to press-fit the synthetic resin into the cavity of the mold fitted with the preformed sheet, and the type of injection molding machine, the sprue, runner, gate, and cavity size in the mold are used. There are no restrictions on arrangement, shape, etc.

According to the present invention, in a method of decoratively molding a sheet having patterns, letters, etc. preformed into a shape having an uneven surface and/or a curved surface, all or part of the edges of the preformed sheet are placed in a cavity. By holding the product with the parting surface of a stationary mold, a movable mold, or a slide core extending along the side wall, a molded product with no wrinkles on the product surface and a neatly decorated end portion can be obtained.

In addition, if the sheet is held on the parting surface of the stationary mold, movable mold, or slide core that extends along the side wall of the cavity, and also on the parting surface that intersects with these surfaces, the product surface will be A painted molded product with wrinkles and clean terminal parts that can be punched automatically can be obtained.

In the present invention, the edges of the preformed sheet are fixed side molds,
The depth h held by the parting surface of the movable mold or slide core is preferably 3 mm or more.

If the depth of the surface where the selvage of the preformed sheet is held is too small, the selvage of the sheet will not be held securely on the parting surface, and the press-fit synthetic resin is likely to be rolled into the sheet surface.

The upper limit of the depth of the surface of the preformed sheet where the selvage is held is not particularly defined, but is usually determined based on the range that allows deep drawing and the common mold thickness at the time of preforming the sheet.

The fixed side mold extends along the side wall of the cavity,
On the parting surface of the moving side mold or slide core,
Furthermore, in the method of holding with a parting surface that intersects with those parting surfaces (for example, Fig. 5 and 6
(Figure), the inner corner radius R where both parting surfaces intersect is preferably 1 to 10 mr/L.

If the corner radius R is less than 1 mvt, the sheet is likely to shift, and if it exceeds 10 mm, the dimensions of the sheet and the injection mold become unnecessarily thick (which is uneconomical).

Applications of products molded by the method of the present invention include:
Meter cases with heathered patterns or letters on uneven or curved surfaces, automobile interior parts such as console boxes, housings for radios, televisions, stereos, air conditioners, etc., light electrical parts such as fan stands, sideboards, fashion cases, etc. Furniture, etc., and is particularly suitable for applications that require added value in terms of appearance.

Hereinafter, the method of the present invention will be explained in detail with reference to the figures.
The method is not limited to more than 0 abstracts and less than 0 examples.

1 Example 1 PVC/ABS laminated sheet with a thickness of 0.7 mm.
The sheet with a heathered pattern printed on the side surface is in close contact with the fixed side mold surface, and the depth of the sheet after molding is 15 mm deeper than the depth of the product (and the corner radius of the bottom of the sheet is 5mm). It was vacuum formed using a wooden mold so that it would look like this.

Next, the vacuum-formed sheet is trimmed so that the depth h at which the sheet is held is 10 mm as shown in Figure 5a, and is mounted on the fixed side mold for injection molding, and then the mold is clamped and the third As shown in the figure, the lugs on the outer periphery of the sheet were held by the parting surfaces of the stationary mold and the movable mold, which extended along the side wall of the cavity.

ABS resin Clarastic MTA (manufactured by Sumitomo Naugatuck) was injected and press-fitted into the mold cavity in a conventional manner, cooled, and opened to obtain a painted molded product.

Furthermore, the unnecessary edge portion of the sheet (the portion held by the parting surface during injection molding) at the end of the molded product was trimmed to obtain the product shown in FIG. 4.

This product not only has no missing or wrinkled sheets on the side end part A, but also has an unnecessary cut surface of the sheet at the end face opening of the product, so the side of the product is completely covered with a painted sheet. It had the most favorable appearance.

Example 2 A sheet vacuum-formed in the same manner as in Example 1 was mounted as it was, with h = 15 mm and R = 5 mm, in the fixed side mold for injection molding as shown in Figure 5, and then the mold was clamped and the outer periphery of the seat was sealed. The parting surfaces of the stationary mold and the movable mold, in which the ears of the parts are extended along the side wall of the cavity, and the parting surface that intersects these parting surfaces (horizontal part in Figure 5) It was held at

Thereafter, a product was obtained in the same manner as in Example 1.

The resulting product, similar to Example 1, had the most favorable appearance.

In addition, in the case of this example, since there is no need to trim the edges of the side surface of the vacuum-formed sheet as in Example 1, the operation is easy and mass production is excellent.

Comparative Example The same sheet as in Example 1 was used, the heathered pattern was in close contact with the fixed side mold surface, and the depth of the sheet after molding was the same as the depth of the product.
Vacuum forming was performed using a wooden mold so that the corner radius at the bottom of the seat was made as small as possible.

Next, this vacuum-formed sheet was attached to a stationary mold for injection molding, and the mold was clamped to extend the selvage on the outer periphery of the sheet along the normal, i.e., end surface of the cavity, as shown in Figure 1. The parting surfaces of the stationary mold and the movable mold (first
(Horizontal part in the figure).

Hereinafter, a product shown in FIG. 2 was obtained in the same manner as in Example 1, but the product had wrinkles on the sheet surface at the side end portion A, and the unnecessary cut surface of the edge portion of the sheet, i.e. Since the part without the heathered pattern was located at the terminal part A on the side of the product, the appearance was significantly impaired.

Example 3 ABS resin sheet printed with a heathered pattern with a thickness of 0.3 mm (Clarastic-254 manufactured by Sumitomo Naugatuck Co., Ltd.)
0〃calendar sheet) so that the heathered pattern is in close contact with the moving side mold surface, and the depth of the sheet after molding is 1 degree lower than the depth of the product.
Vacuum forming was performed using a wooden mold so that the corner radius at the bottom of the sheet was 0 mm deep and 3 mm.

Next, after installing this vacuum-formed sheet into the movable side mold for injection molding, the slide core and the movable side mold are closed and clamped, and the ears on the outer periphery of the sheet are extended along the side wall of the cavity. The parting surface of the movable side mold and the slide core, which also intersect with these parting surfaces (horizontal part in Figures 5 and 6)
It was held at

A product was obtained in the same manner as in Example 1.

The obtained product had a picture painted on the inner wall surface of the molded product, and was excellent in both appearance and operability as in Example 2.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of the mold when a preformed sheet is attached to the stationary mold and held by a conventional method. FIG. 2 is a partial cross-sectional view of a painted molded product obtained by a conventional method. FIG. 3 and FIG. 5a are partial sectional views of the molds when the preformed sheet is held by the parting surfaces of the stationary mold and the movable mold extending along the side wall of the cavity. FIG. 4 is a partial sectional view of a decorated molded product obtained by the method of the present invention. Figure 5 shows that the preformed sheet was held by the parting surfaces of the stationary mold and movable mold extending along the side wall of the cavity, and also by the parting surfaces intersecting these parting surfaces. A partial cross-sectional view of the mold at the time. Figure 6 shows the state in which the preformed sheet is held at the parting surfaces of the moving mold and slide core extending along the side wall of the cavity, and also by the parting surfaces intersecting these parting surfaces. A partial cross-sectional view of the mold. 1... Fixed side mold, 2... Moving side die, 3... Cavity, 4... Preformed sheet, 5... ...Press-fitted synthetic resin, 6
...Slide core.

Claims (1)

[Scope of Claims] 1. In a method of decoratively molding a sheet having patterns, letters, etc. preformed into a shape having an uneven surface and/or a curved surface, all or part of the edges of the preformed sheet are formed into cavities. A method for manufacturing a decorated molded product, characterized in that the molded product is held by a parting surface of a stationary mold, a movable mold, or a slide core extending along the side wall of the molded product. 2 The depth of the surface of the preformed sheet where the ears are held is 3.
The method for manufacturing a painted molded article according to claim 1, wherein the diameter is 1 mm or more. . 3. In a method of decoratively molding a sheet having patterns, letters, etc., preformed into a shape with uneven surfaces and/or curved surfaces, etc., all or part of the edges of the preformed sheet are molded along the side wall of the cavity. A method for manufacturing a painted molded product, which comprises holding the molded product by a parting surface of an extended stationary mold, a movable mold, or a slide core, and further by a parting surface that intersects with the parting surface. 4 The depth of the surface where the ears of the preformed sheet are held is 3
The method for producing a painted molded article according to claim 3, wherein the diameter is 3 mm or more. 5 The inner corner radius where the parting surfaces intersect is 1
5. The method for producing a painted molded article according to claim 4, which has a thickness of 10 mm.