JPH1128732A - Method and mold for powder slush molding of skin material for instrument panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable precise formation of a local thick-wall part in a desired place of a skin material by making only a simple improvement in a mold structure. SOLUTION: Out of a plurality of heating medium temperature regulating pipes 1 provided in a state of contact on the rear side 2b of a mold main body 2, a pipe 1A provided at a place corresponding to a required part 5a of a skin material 5 for an instrument panel to be subjected to slush molding is made to have an inside diameter d1a larger than the inside diameters d1 of the other pipes 1 so that the flow rate and heat quantity of a heating medium in the pipe 1A having the larger diameter be larger than those in the other pipes 1, in this method for powder slush molding. By this constitution, the amount of resin powder sticking on a molding surface 2a of the mold main body 2 is made to differ in places and thereby the skin material 5 for the instrument panel of which the required part 5a is thick in wall locally is molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder slush molding method applied to, for example, molding a skin material for an airbag interior instrument panel for an automobile.
More specifically, the molding die body is heated by circulation of a heating medium such as oil, and a resin powder is adhered to the inner surface of the heated die body and melt-hardened to form a skin material for an instrument panel. The present invention relates to a method for forming a powder slash of a skin material for an instrument panel and a mold for forming the powder slush.

[0002]

2. Description of the Related Art In the case of a skin material for an instrument panel of this kind, for example, when it is a skin material for an automobile, the thickness of a portion which is liable to be thermally degraded due to heating by direct sunlight is made thicker than other portions. There is a demand to increase the heat resistance of the corresponding part by increasing the thickness. In particular, for the skin material for the instrument panel that houses the airbag, the wall thickness around the airbag interior part prevents the occurrence of the situation where the deployment performance of the airbag changes (deteriorates) due to thermal deterioration due to solar radiation or the like. It is strongly desired to locally increase the thickness to improve the heat resistance.

[0003] Such a demand, that is, a powder slush molding method for locally increasing the thickness of an instrument panel has conventionally been proposed in (A), for example, JP-A-6-23.
As disclosed in JP-A-8685, a resin box containing a resin powder and a molding die heated to a predetermined temperature and set to a state in which the opening end of the powder box is closed are rotated. When the powder material is adhered to the molding surface of the molding die and melted to form the skin material, during the rotation of the powder box and the molding die,
By temporarily stopping the rotation for a predetermined time when the portion corresponding to the required thick portion of the skin material is at the lower position,
A method of forming a thick portion on a skin material to be slush-molded,
(B) For example, as disclosed in Japanese Patent Application Laid-Open No. 4-288209, a local heating means such as a heater is buried in a part of a molding surface of a molding die, and a part of the die is A method of forming a thick portion on a part of a skin material by heating to a higher temperature than other portions via a local heating means, (c) disclosed in, for example, JP-A-6-039859. As described above, a plurality of heating medium circulation pipes are arranged in contact with the back surface of the molding die, and the circulation flow rate of the heating medium into the plurality of heating medium circulation pipes is controlled by controlling the opening and closing of valves. Thus, a method of forming a thick portion on a part of the skin material to be slush-formed is known.

[0004]

However, in the conventional powder slush molding method described above, in the method (a), it is difficult to form a part of the skin material in one direction in a thick portion over the entire width thereof. Even if possible, it is not possible to form a locally thick portion such as only around the airbag interior. In the method of (b), it is necessary to embed a local heating means such as a heater in a part of a molding die so as not to hinder predetermined slash molding.
There is a problem that not only the mold structure becomes complicated and expensive, but also its maintenance is difficult. Furthermore, (c)
The method requires a number of components such as a valve and a controller for controlling the opening and closing of the valve, which makes the structure complicated and expensive, and it is technically difficult to control the opening and closing of the valve. If there is an error, the flow rate of the heating medium greatly changes, and as a result, there is a problem that the thickness of the thick portion does not become constant, and the accuracy and heat resistance strength tend to vary from product to product.

The present invention has been made in view of the above circumstances, and a local thick portion can be accurately formed at a desired portion of a skin material only by making a simple improvement in a mold structure. An object of the present invention is to provide a powder slush molding method and a molding die for a skin material for an instrument panel.

[0006]

According to a first aspect of the present invention, there is provided a powder slush molding method for a skin material for an instrument panel according to the first aspect of the present invention. Heating the heating medium to a predetermined temperature by circulating the heating medium in the heating medium temperature control pipe, adheres resin powder to the molding surface of the molding die body, and melts and cures it to form the skin material for the instrument panel. A powder slush molding method for a skin material for an instrument panel, wherein an inner diameter of a pipe corresponding to a required portion of the skin material to be slush-molded among the plurality of heating medium temperature-regulated pipes has an inner diameter of another pipe. The heating medium is formed to be larger than the inside diameter, and the heating medium is circulated through each of the plurality of heating medium temperature control pipes to form the inside diameter of the mold body. By heating the portion where the large pipe is disposed to a higher temperature than the other portions, more resin powder is attached to the portion heated at the higher temperature than the other portions, and the thickness of the required portion is increased. It is characterized in that a skin material for a mental panel is formed.

According to a second aspect of the present invention, there is provided a powder slush molding mold for a skin material for an instrument panel, wherein a plurality of heating medium temperature control pipes are disposed in contact with the back surface. The mold body is heated to a predetermined temperature by circulating a heating medium into the pipe, and a resin powder is adhered to a molding surface of the heated mold body and melt-hardened to form a skin material for an instrument panel. A powder slush molding mold for an instrument panel skin material, wherein the plurality of heating medium temperature control pipes are made of the same material, and a portion corresponding to a required portion in the skin material to be slush molded. The inner diameter of the pipe is formed larger than the inner diameter of the other pipes, and the heating medium is circulated through all of the plurality of heating medium temperature control pipes. When in, it is characterized in that the flow rate in the inner diameter of the larger pipe is configured to be larger than the flow rate of the smaller inner diameter pipe.

According to the first and second aspects of the present invention, a local heating means such as a heater is buried in a part of a molding surface of a molding die or a plurality of heating means are provided. There is a difference in the inner diameter of multiple heating medium temperature control pipes without using extremely difficult means both structurally and technically, such as controlling the opening and closing amount of a valve connected to the medium temperature control pipe. By simply making a simple and inexpensive improvement in the mold structure, the difference between the flow rate and heat quantity of the heating medium flowing through the pipe with a large inside diameter and the flow rate and heat quantity within the pipe with a small inside diameter causes It is possible to always heat the part where the large pipe is disposed to a constant high temperature compared to other parts, so that the amount of resin powder attached to the high-temperature heated part becomes smaller than the amount of resin powder attached to the other part. than No longer forms accurately so as not variation in a thick local thick part of the wall thickness for each product than other portions on the required portion of the skin material to be slush molding,
The heat resistance of that portion can be improved as predetermined.

Further, in the powder slush molding die of the skin material for an instrument panel according to the second aspect of the present invention, the plurality of heating medium temperature control pipes have a difference in inner diameter. The flow rate from the heating medium distribution manifold to each pipe changes significantly more than the flow rate difference due to the inner diameter difference, that is, heating to the pipe side having the larger inner diameter compared to the pipes having the same inner diameter. The medium is drifted, and the thickness of the thick portion and the thin portion formed in the required portion of the skin material may not be as specified. Focusing on this point, in the invention according to claim 3, the plurality of heating medium temperature control pipes and the plurality of heating medium distribution manifolds are connected via flexible hoses having nipples at both ends. Yes, by adopting such a configuration, with a simple means of changing the diameter of the nipple, adjust the flow rate to each pipe so that it does not drift more than the flow rate difference due to the inner diameter difference, It is possible to accurately form a locally thick portion and a thin portion having a predetermined thickness.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional structural view of an entire molding die of a pipe heating system (modular method) applied to a powder slush molding method of a skin material for an instrument panel according to the present invention. In FIG. A commonly known nickel molding die body having a back surface 2b
A plurality of copper or steel pipes 1 through which a heating medium such as heating oil circulates are arranged at equal intervals. These pipes 1 are fixed to the mold body 1 by silver brazing or soldering in a state where a part of the peripheral surface thereof is in contact with the back surface 2 b of the mold body 2.

A powder box 4 containing a resin powder 3 is set on the molding surface 2a side of the mold body 2 so that an opening thereof is closed by the mold body 2. By circulating a heating medium in the plurality of pipes 1, the mold body 2 heated to a predetermined temperature, for example, 230 to 250 °, is given a motion such as rotation, so that the mold body 2 is accommodated in the powder box 4. The resin powder 3 is adhered to the molding surface 2a of the mold body 2 and melt-hardened to form the instrument panel skin material 5 having a shape corresponding to the shape of the molding surface 2a by slush molding.

Of the plurality of heating medium temperature control pipes 1, a required portion of the skin material 5 to be slush-molded, for example, the instrument panel skin material 5 for an automobile as shown in FIG. As shown in FIG. 6, a portion 5 a that is heated by being irradiated with direct sunlight through a window, or, as shown in FIG. 6, a portion 5 a around the interior portion of the airbag 6 when the instrument panel skin material 5 houses the airbag 6. When the diameter of the pipe 1A at the position corresponding to the above is formed larger than the diameter of the other pipes 1 and the heating medium is circulated through all the pipes 1 and 1A, the flow rate and the amount of heat in the pipe 1A on the large diameter side become It is configured to be larger than the flow rate and heat quantity in the pipe 1 on the small diameter side. Specifically, as clearly shown in FIG. 2, when the mold thickness t of the mold body 2 is set to 4 mm, the pipe 1A at a position corresponding to the required portion 5a of the skin material 5 has an inner diameter d1a of 13 mm.
The outer diameter d2a is 15 mm, and the other pipes 1
The inner diameter d1 is set to 7 mm, and the outer diameter d2 is set to 10 mm.

The plurality of heating medium temperature control pipes 1 and 1A
The heating medium distribution manifold 12 and the heating medium assembly connected to the heating medium supply elbow 8 and the heating medium discharge elbow 9 fixed to both ends of the frame 7 holding the mold body 2 by flexible hoses 10 and 11, respectively. The flexible manifolds 14 and 15 are connected to a plurality of portions of the use manifold 13, respectively. One end of each of the flexible metal hoses 14 and 15 is provided with a wire as shown in FIG.
As shown in FIG. 5, a nipple 17 which can be screwed to a socket 16 welded to a plurality of locations of the manifolds 12 and 13 is attached via a cap nut type joint 18, and
At the other end, as shown in FIG.
A threadable socket 20 is attached to a nipple 19 welded to the end of the pipe, whereby each of the pipes 1 and 1A and a plurality of locations of each of the manifolds 12 and 13 are
It is configured to be connected via flexible metal hoses 14 and 15 having nipples 17 and 19 at both ends.

Next, a method of molding the skin material 5 for an instrument panel using the above-described powder slush molding die will be described. First, a heating fluid such as heating oil is supplied and circulated through the supply elbow 8, the flexible hose 10, the distribution manifold 12, and the flexible metal hose 14 into the plurality of pipes 1 and 1A, thereby setting the mold body 2 to a predetermined position. Temperature, for example 230
Heat to ~ 250 °. Here, since the flow rate and the amount of heat of the heating medium flowing through the pipe 1A having the large inner diameter d1a are larger than the flow rate and the amount of heat of the heating medium flowing through the pipe 1 having the small inner diameter d1, the inner diameter d1 of the mold body 2 is large.
The portion where the pipe 1A having the larger a is disposed is always heated to a constant high temperature compared to other portions.

In this state, when a motion such as rotation is applied to the powder box 4 containing the mold body 2 and the resin powder 3, the resin powder 3 contained in the powder box 4 forms the mold body 2. The instrument panel skin material 5 having the shape corresponding to the shape of the molding surface 2a is slush-molded by being attached to the surface 2a and melt-hardened. A larger amount of the resin powder 3 is attached than the part, and the resin powder 3 is melt-hardened, so that the thickness of the required portion 5a of the skin material 5 to be slush-molded is larger than the thickness of the other portions 5b. The skin material 5 having a locally thickened portion and having such a locally thick portion 5a is manufactured.

In the instrument panel skin material 5 manufactured as described above, since the heat resistance of the thick portion 5a is improved, for example, an instrument for an automobile as shown in FIGS. When used as the panel skin material 5, even if it is irradiated with direct sunlight through the front window and heated, there is little thermal deterioration, and it is possible to maintain a predetermined performance even after long-term use.

The plurality of heating medium temperature control pipes 1 and 1A and a plurality of heating medium distribution and heating medium collecting manifolds 12 and 13 have nipples 1 at both ends.
Flexible metal hoses 14, 15 provided with 7, 19
Are connected via the nipples 17 and 19, so that the nipples 17 and 19 can be easily changed by simply changing their diameters.
It is possible to adjust the flow rate to the pipes 1 and 1A having different diameters so as not to be deviated more than the flow rate difference due to the inner diameter difference, and to provide the skin material 5 with a locally thick portion 5a and a thin portion 5b having a predetermined thickness.
Can be formed accurately.

The slush molding resin powder contains a vinyl chloride resin as a main component, a plasticizer,
Even if a resin powder obtained by mixing stabilizers and other additives in appropriate amounts is used, besides this, a resin powder mainly composed of a thermoplastic elastomer such as an olefin-based thermoplastic elastomer or a styrene-based thermoplastic elastomer is used. It may be used, and in this case, the lightness and cleanness of the skin material can be improved.

[0019]

As described above, claims 1 and 2 are as described above.
According to the invention described in (1), the local heating means such as a heater is embedded in a part of the molding surface of the molding die, or the opening / closing amount of a valve connected to a plurality of heating medium temperature control pipes is controlled. Rather than using extremely difficult means, both structurally and technically, it is only possible to make simple and inexpensive improvements to the mold structure, such as making the inner diameters of multiple heating medium temperature control pipes different. A part of the mold body is always heated to a certain temperature higher than other parts, and the slush-molded skin is formed by the difference between the amount of resin powder attached to the high-temperature heated part and the amount of resin powder attached to the other part. A locally thick part, which is thicker than other parts, can be formed accurately in the required part of the material so that there is no variation between products, and the heat resistance of the thick part is improved as specified It has the effect that it can be done.

According to the third aspect of the present invention, in addition to the above-described effects, the heating medium is deviated more than the flow rate difference due to the inner diameter difference of each pipe by a simple means such as changing the diameter of the nipple. Thus, a skin material having a locally thick portion and a thin portion having a predetermined thickness can be accurately manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional structural view of an entire molding die of a piping heating method (modular method) applied to a powder slush molding method of a skin material for an instrument panel according to the present invention.

FIG. 2 is an enlarged sectional view taken along line XX of FIG.

FIG. 3 is a plan view of a main part of the molding die shown in FIG.

FIG. 4 is an enlarged view of a portion A in FIG. 1;

FIG. 5 is a perspective view of a main part when a skin material manufactured by the method of the present invention is used as a skin material for an instrument panel in an automobile.

FIG. 6 is a perspective view of a main part when a skin material manufactured by the method of the present invention is used as a skin material for an airbag interior instrument panel in an automobile.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating medium temperature control pipe (small diameter) 1A Heating medium temperature control pipe (large diameter) 2 Mold main body 2a Molding surface 2b Back surface 3 Resin powder 5 Skin material 5a Required part (thick part) 12,13 Manifold 14,15 Flexible Metal hose 17, 19 Nipple

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 31:58

Claims (3)

[Claims] 1. A resin powder is applied to a molding surface of a molding die body heated to a predetermined temperature by circulating a heating medium through a plurality of heating medium temperature control pipes disposed in contact with the back surface. A powder slush molding method of an instrument panel skin material for forming an instrument panel skin material by attaching and melting and curing the skin material, wherein the skin material is slush-molded among the plurality of heating medium temperature control pipes. The inner diameter of the pipe at a location corresponding to the required part is formed larger than the inner diameters of the other pipes, and a heating medium is circulated through each of the plurality of heating medium temperature control pipes to form an inner diameter of the mold body. By heating the portion where the large pipe is disposed to a higher temperature than the other portions, the portion heated at the high temperature has more resin powder than the other portions. Deposited allowed by powder slush molding method of the instrument panel skin material, which comprises forming a wall thickness greater instrument panel skin material of the required portions. 2. A molding die main body having a plurality of heating medium temperature control pipes disposed on a back surface thereof in contact with each other is heated to a predetermined temperature by circulating a heating medium into the pipes. A powder slush molding mold for an instrument panel skin material for forming a skin material for an instrument panel by adhering a resin powder to a molding surface of a mold body and melting and curing the resin powder. The temperature control pipe is made of the same material, and the inner diameter of the pipe corresponding to a required portion of the skin material to be slush-formed is formed to be larger than the inner diameters of the other pipes. When the heating medium is circulated all over the temperature control pipe, the flow rate in the pipe with a large inside diameter is configured to be larger than the flow rate in the pipe with a small inside diameter. Powder slush molding die of the instrument panel skin material, characterized in that there. 3. The instrument panel according to claim 2, wherein the plurality of heating medium temperature control pipes and a plurality of heating medium distribution manifolds are connected via flexible hoses having nipples at both ends. Powder slush molding die for skin material.