JPH06344433A - Vacuum molding method - Google Patents

Abstract

PURPOSE:To provide a product having an undercut by vacuum molding without using a movable mold. CONSTITUTION:A female mold 30 and a male mold 40 are clamped. Firstly vacuum suction is performed from the female mold 30 side. Thereby a sheet 13 is pressed and stuck to the internal face of the female mold 30. After vacuum suction performed from the female mold 30 side is stopped, the vacuum suction is performed from the male mold 40 side. Thereby, the sheet 13 is pressed and stuck to the downside part from the undercut part 4 of core material 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum forming method suitable for forming a product having an undercut portion such as an automobile interior product.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 7, an instrument panel A which is one of automobile interior parts is composed of a core material 1, a cushion material 2 and a skin 3 which are sequentially laminated. The core material 1 is for maintaining a constant shape of the entire instrument panel A, is made of a hard resin such as ABS resin, and is molded by, for example, an injection molding method. The cushion material 2 is made of a foam material such as polypropylene foam, and the skin 3 is made of, for example, a resin in which polyvinyl chloride and ABS resin are mixed, and both are integrated by laminating.
Then, the cushion material 2 is adhered to the core material 1 to integrate the core material 1, the cushion material 2 and the outer skin 3. The core material 1 has the instrument panel A.
A large number of small holes are formed penetratingly because it is necessary to circulate air when vacuum forming.

The instrument panel A is usually
It is manufactured by the vacuum forming method. In this case, since the instrument panel A has the convex undercut portion 4, it is vacuum formed as follows.

That is, reference numeral 10 in FIG. 8 is a vacuum molding die apparatus comprising a male die 11 and a female die 12, and when the instrument panel A is formed using the die apparatus 10. , The male mold 11 and the female mold 12 are separated from each other and opened, and the cushion material 2 is provided between them.
A sheet 13 composed of the skin and the skin 3 is stretched. Next, the core material 1 is set in the male mold 11. In this case, an adhesive is applied to the surface of the core material 1 in advance. Then, the male die 11 is moved closer to the female die 12, and the core material 1 and the sheet 13 are inserted into the female die 12. Then, the portion of the sheet 13 that should be above the undercut portion 4 of the instrument panel A is pressed into contact with the inner surface of the female die 12.

Next, the movable dies 12a and 12b of the female die 12 are moved to press the sheet 13 from the undercut portion 4 of the core material 1 to the portion corresponding to the lower side as shown by an imaginary line. Then, the female die 12 and the movable dies 12a, 12b
Vacuum suction from. As a result, the outer skin 3 is given a shape such as a diaphragm. After the vacuum forming, the movable molds 12a and 12b are retracted, and then the mold is opened to take out the molded product. And
The portion of the sheet 13 not adhered to the core material 1 is cut off.
Thereby, the instrument panel A is obtained.

[0006]

In the above-mentioned conventional vacuum forming method, there is a small gap between the female die 12 and the movable dies 12a, 12b for allowing the movable dies 12a, 12b to move. The sheet 13 is also vacuumed. Therefore, on the surface of the outer skin 3 of the manufactured instrument panel A, streaks along the gap are formed at the portions corresponding to the gap (portions indicated by reference characters a and b in FIG. 8), and the instrument panel There was a problem that spoiled A's aesthetics.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and when molding a product having a surface of a core material with an outer skin adhered, an adhesive is applied to the surface. The core material is set in the male mold, and the male mold is moved relatively to the female mold side so that the epidermis stretched between the male mold and the female mold is brought into contact with the core material and the inner surface of the female mold is In this state, vacuum suction is performed from the female mold side, and after vacuum suction from the female mold side is stopped, vacuum suction is performed from the male mold side. In this case, it is desirable to forcibly move the peripheral edge portion of the skin toward the core material side during vacuum suction from the male mold side.

[0008]

With the vacuum suction from the female mold side, the epidermis is pressed against and brought into contact with the inner surface of the female mold, so that the surface of the female mold has a shape such as a diaphragm formed on the inner surface of the female mold. When vacuum suction is performed from the male mold side after stopping vacuum suction from the female mold side,
Due to the suction force, a portion of the skin corresponding to the undercut portion is pressed into contact with the core material and fixed by an adhesive.

If the peripheral portion of the skin is fixed during vacuum suction from the male side, the portion of the skin corresponding to the undercut portion is brought into contact with the core material by vacuum suction from the male side. It is greatly stretched. At this time, if the force required for stretching the epidermis is large, the contact pressure of the epidermis with respect to the core material due to vacuum suction is weakened accordingly, and there is a possibility that the fixing force is reduced. Further, by being stretched, the relevant portion becomes thinner than other portions. In this respect,
If the peripheral portion of the skin is forcibly moved to the core side, the skin will not be stretched or the amount of stretching will be reduced. Therefore, the fixing force does not decrease, or the epidermis does not become partly thin.

[0010]

Embodiments of the present invention will now be described with reference to FIGS.
Will be described with reference to. 1 to 3 show a mold apparatus 20 for carrying out the present invention, and the mold apparatus 20 is adapted to mold an instrument panel A shown in FIG. 7. First, the configuration of the mold device 20 will be described. The mold device 20 is arranged between the female mold 30 and the male mold 40 facing each other and the female mold 30 and the male mold 40, and the sheet 13 And a pair of holding frames 50, 50 for fixing the peripheral edge portion of the.

As shown in FIGS. 2 and 3, the female die 30 is provided with a rod 31 which is vertically moved by a driving means (not shown), and a lower end portion of the rod 31 is made of metal. The frame 32 of is fixed. The frame 32 has a hollow rectangular parallelepiped shape with an opening at the center of the lower end, and an upper die 33 is housed inside the frame 32.

A recess 34 is formed on the lower end surface of the upper mold 33. The width of the lower end opening of the recess 34 is approximately the same as the width W of the instrument panel A, and the length of the recess 34 is approximately the same as the length of the instrument panel A. Further, the upper bottom portion of the recess has the same sectional shape as the portion above the undercut portions 4, 4 of the instrument panel A. Furthermore, the recess 3
A desired pattern or the like to be applied to the skin 3 such as a diaphragm is formed on the inner surface of 4.

Here, the pattern is applied to the outer skin 3 by vacuum suction of the outer skin 3 so that the inner skin of the concave portion 34 is pressed and brought into close contact. 33 is formed of porous ceramics. Therefore, when the suction hole 35 penetrating the rod 31 and the frame 32 is connected to a vacuum suction means (not shown) such as a vacuum pump or a vacuum tank to perform vacuum suction, the skin 3
Are pressed and closely attached to the inner surface of the recess 34. Of course, the upper skin 33 can be vacuum-sucked by forming the upper mold 33 with resin or another material and opening a large number of small holes communicating with the suction holes 35 on the inner surface of the recess 34.

On both sides of the lower surface of the frame 32, the sandwiching pieces 3 are provided.
6 and 36 are the width direction of the frame body 32 (left and right direction in FIG. 2)
It is provided slidably to each. Each sandwiching piece 36
Are moved close to and away from each other by a cylinder mechanism 60 arranged and fixed on the end face of the frame body 32 in the longitudinal direction. The sandwiching piece 36 is positioned such that its side surface is flush with the side surface of the frame body 32 in the initial state.

The male die 40 has a rod 41 which can be moved in the vertical direction by a driving means. A substrate 42 is fixed to the upper end of the rod 41. The lower die 43 is fixed to the upper surface of the substrate 42. The width of the lower mold 43 is substantially the same as the narrowest width inside the core material 1 (width of the lower end portion in FIG. 7) so that the core material 2 fits in the upper end portion of the lower mold 43 without play. Its length is substantially the same as the inner length of the core material 1.

The lower mold 43 is made of a hard resin having excellent heat resistance, and the inside of the lower mold 43 penetrates the substrate 42 and the rod 41 and is connected to a vacuum suction means (not shown). The hole 44 is formed and the suction hole 4 is formed.
A large number of small holes (not shown) communicating with No. 4 are formed. Each small hole is opened substantially uniformly on the outer surface of the lower mold 43. The lower mold 43 may be made of porous ceramic. In that case, needless to say, it is not necessary to form a small hole in the lower mold 43.

On both sides of the upper surface of the substrate 42, sandwiching pieces 45, 45 are provided so as to be slidable toward and away from each other. The holding pieces 45 are the holding pieces 3 of the female die 30.
Similar to 6, it can be moved by a cylinder mechanism (not shown). Further, in the initial state, it is positioned so as to face the sandwiching piece 36 of the female die 30.

Next, a case where the instrument panel A is molded by the mold apparatus 20 having the above structure will be described. First, as shown in FIG. 2, the female die 30 and the male die 40 are separated from each other, and the core material 1 is attached to the upper end portion of the lower die 43 of the male die 40.
And the peripheral portions of the sheet 13 are fixed by the sandwiching frames 50, 50. In this case, an adhesive is applied to the surface of the core material 1 (the surface to which the cushion material 2 is bonded). As for the sheet 13, the skin 3 is replaced by the female mold 3.
Turn to the 0 side.

Next, the sheet 13 is heated by a heater (not shown). After heating, the female die 30 is moved downward and the male die 40 is moved upward. The female die 30 is stopped when the sandwiching piece 36 contacts the sheet 13. If the female die 30 is arranged close to or in contact with the sheet 13 from the beginning, the female die 30 may not be moved.

On the other hand, with respect to the male die 40, even after the core material 1 has come into contact with the sheet 13, the male die 40 is further moved upward so that the central portion of the sheet 13 is pushed into the concave portion 34 of the female die 30. Then, the sheet 13 comes into pressure contact with the upper bottom portion of the recess 34, or immediately before that, the male die 40 is stopped.
At this time, the holding piece 36 of the female die 30 and the holding piece 4 of the male die 40
5 and the sheet 13 are pressed into contact with each other to be clamped,
As a result, the inside of the recess 34 is sealed.

Next, the vacuum suction means is activated and the sheet 1
3 is vacuumed from the female mold 30 side. Then, FIG. 1 (A)
As shown in FIG. 5, the sheet 13 is pressed and closely attached to the inner surface of the recess 34. As a result, the sheet 13 is formed into a desired shape, and the pattern such as a diaphragm formed on the inner surface of the concave portion 34 is transferred to the surface skin 3 of the sheet 13. When the time required for forming the shape and transferring the pattern elapses, the vacuum suction from the female mold 30 side is stopped.

Immediately after the vacuum suction from the female die 30 side is stopped, vacuum suction from the male die 40 side is performed. Then, since a large number of small holes are formed in the core material 1, the sheet 13 is vacuum-sucked through the small holes. As a result, as shown in FIG. 1 (B), the sheet 13 is pressed and brought into close contact with the core material 1. in this case,
Of course, the portion of the seat 13 corresponding to the portion above the undercut portion 4 of the instrument panel A is pressed and brought into close contact with the core material 1, and the portion corresponding to the portion below the undercut portion 4 is Then, the core material 1 is pressed and brought into close contact by vacuum suction from the male die 30 side. Of course, the sheet 13 also press-contacts the lower mold 43.

During the vacuum suction from the male die 40 side, compressed air is supplied to the female die 30 through the suction holes 35 so that the female die 30
A positive pressure may be applied to the sheet 13 from the side. Similarly, a positive pressure may be applied to the sheet 13 from the male die 40 side during vacuum suction from the female die 30 side.

At the time of vacuum suction from the male die 40 side, at the same time, the cylinder mechanism 60 installed in the female die 30 and the cylinder mechanism installed in the male die 40 are activated, and the clamping piece 3
6, 45 are moved so as to approach the lower mold 43 while maintaining the state in which the sheet 13 is clamped. The reason for this point will be described later. When the holding pieces 36, 45 are moved, the holding frames 50, 50 may hold the sheet 13 in between, but the holding frames 50, 50 are moved away from each other and the sheet 1 is moved.
It is desirable that the peripheral portion of 3 be free to move.

When the molding is completed, the female die 30 and the male die 4 are formed.
0 is moved apart, and so-called mold opening is performed. Then, the molded product is taken out of the male mold 40, and the core material 1 of the sheet 13 is taken out.
Cut off the part that is not in close contact with. Thereby, the instrument panel A is obtained.

As described above, in the vacuum forming method of the present invention, the sheet 13 is vacuum sucked from the female mold 30 side to form the concave portion 34.
After applying the desired shape and pattern to the outer skin 3 by pressing it to the inner surface, the vacuum suction from the female die 30 side is stopped, while the vacuum suction from the male die 40 side is performed. When molding the instrument panel A which it has, it is not necessary to use a movable mold. Therefore, it is possible to reliably prevent the occurrence of stripes on the skin 3.

Further, in this embodiment, the sandwiching pieces 36, 45 are provided.
Is moved to the lower die 43 side so that the peripheral edge of the sheet 13 is moved closer to the core material 1, so that the sheet 13 is reliably pressed and contacted from the undercut portion 4 to the lower core material 1. Can be made.

That is, assuming that the sheet 13 is vacuum-sucked from the male die 40 side with the sandwiching pieces 36 and 45 fixed in position, the sheet 13 is a portion below the undercut portion 4 of the core material 1. In order to make close contact with, the portion between the portion corresponding to the undercut portion 4 and the portion sandwiched by the sandwiching pieces 36, 45 needs to greatly expand, and a large tensile stress acts on the sheet 13. Therefore, the sheet 13 may not be pressed and adhered to the core material 1. Further, the portion that is largely stretched becomes thinner than the other portion (the portion above the undercut portion 4).

In this respect, in the above embodiment, the male type 4
Since the peripheral edge of the sheet 13 is moved so as to approach the core material 1 during vacuum suction from the 0 side, during vacuum suction from the male die 40 side, a portion below the undercut portion 4 of the sheet 13 is removed. The amount of elongation can be reduced. Therefore, the portion of the sheet 13 can be surely pressed and brought into close contact with the core material 1. Moreover, since the amount of elongation is small, it is possible to prevent the relevant portion from becoming larger and thinner than other portions.

Next, another embodiment of the present invention will be described.
The embodiment shown in FIG. 4 is for the case where the amount of protrusion of the undercut portion 4 is relatively small, and in this embodiment,
Rollers 37, 4 instead of the sandwiching pieces 36, 45 of the above embodiment.
6 is arranged so that the sheet 13 is movably held by these rollers 37 and 46. In this embodiment, when vacuum suction is performed from the male die 40 side, the suction force pulls the sheet 13 and the peripheral portion of the sheet 13 automatically moves. Note that reference numeral 38 is a seal material made of rubber or the like for ensuring airtightness between the frame body 32 and the roller 37 by contacting the roller 37, and reference numeral 47 is also the same seal material.

The embodiment shown in FIGS. 5 and 6 is for molding a product having a concave undercut portion. As shown in FIG.
After vacuum suction from the side of the male mold 40 to bring it into close contact with the inner surface of the recess 34, the vacuum suction from the female mold 30 side is stopped and the male mold 40
Vacuum suction from the side. Then, as shown in FIG. 6, the sheet 13 is formed in the recess 1a of the core material 1 corresponding to the undercut portion.
Stick to each other.

The present invention is not limited to the above embodiments, but can be modified as appropriate without departing from the scope of the invention. For example, according to the present invention, in addition to the instrument panel A described above, interior parts for vehicles such as door trims, or products other than those for vehicles can be molded. In this case, the cushion material 2 may or may not be provided between the core material 1 and the skin 3.

[0033]

As described above, according to the vacuum forming method of the present invention, since the vacuum suction from the female mold side is stopped and then the vacuum suction is performed from the male mold side, it has an undercut portion. The product can be molded without using a movable mold. Therefore, it is possible to reliably prevent the generation of streaks due to the use of the movable type.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mold device for carrying out the method of the present invention in a mold-clamped state, and FIG. 1 (A) is a drawing showing a vacuum suction state from a female mold side, FIG. FIG. 9B is a diagram showing a state in which vacuum suction from the female mold side is stopped and vacuum suction is performed from the male mold side.

FIG. 2 is a cross-sectional view showing the mold apparatus with the mold opened.

FIG. 3 is a perspective view showing a female mold of the mold device.

FIG. 4 is a cross-sectional view showing a part of another example of a mold device for carrying out the method of the present invention.

FIG. 5 is a cross-sectional view showing still another example of the mold device for carrying out the method of the present invention in a state where the mold is clamped and vacuum suction is performed from the female mold side.

[FIG. 6] Stopping vacuum suction from the female mold side of the same mold device,
It is a cross-sectional view showing a state in which vacuum suction is performed from the male mold side.

FIG. 7 is a sectional view showing an instrument panel molded by the method of the present invention.

FIG. 8 is a cross-sectional view showing a mold device for carrying out a conventional vacuum forming method.

[Explanation of symbols]

 A Instrument panel 1 Core material 3 Skin 4 Undercut part 13 Sheet 20 Mold device 30 Female mold 34 Recessed part 36 Clamping piece 37 Roller 40 Female type 45 Clamping piece 46 Roller

Claims (2)

[Claims] 1. When molding a product in which a skin is adhered to the surface of a core material, the core material having the surface coated with an adhesive is set in a male mold, and the male mold is relatively moved to the female mold side. By doing so, the epidermis stretched between the male mold and the female mold is brought into contact with the core material and along the inner surface of the female mold, and in this state, vacuum suction is performed from the female mold side, and then the female mold side The vacuum forming method is characterized in that the vacuum suction from the male mold side is performed after the vacuum suction from is stopped. 2. The vacuum forming method according to claim 1, wherein the peripheral edge portion of the skin is forcibly moved toward the core material side during vacuum suction from the male mold side.