GB2288145A

GB2288145A - Mould tool having grooved surface for venting of gases

Info

Publication number: GB2288145A
Application number: GB9507280A
Authority: GB
Inventors: Mie Sasaki; Yoshihisa Sato
Original assignee: Ikeda Bussan Co Ltd
Current assignee: Ikeda Corp
Priority date: 1994-04-07
Filing date: 1995-04-07
Publication date: 1995-10-11
Anticipated expiration: 2015-04-07
Also published as: GB9507280D0; JP2862790B2; GB2288145B; JPH07276375A

Abstract

A mold unit for molding a shaped object, e. g. a vehicle ceiling board, from a plastic-impregnated substrate comprises a shaping die 11A having a contoured recess 11A and a shaping die 11B having a mating contoured bulge, for compressing the substrate therebetween, the shaping surface 12 of at least one die (11A) has plurality of grooves 13, each terminating at opposed edges of the die to discharge gas released during molding. <IMAGE>

Description

MOLD UNIT The present invention relates in general to mold units for molding shaped objects, and more particularly to mold units of a type which comprises lower and upper shaping dies by which, for producing a shaped object, a plasticimpregnated preformed substrate is pressed with the application of heat. More specifically, the present invention is concerned with the mold unit for molding from the substrate a ceiling board for a motor vehicle or the like.

In order to clarify the task of the present invention, one conventional mold unit 1 for molding a ceiling board 10 as shown in Fig. 4 will be described with reference to Fig. 5.

As is seen from Fig. 5, the mold unit 1 comprises lower and upper shaping dies 1A and 1B.

The lower shaping die 1A is formed at its upper surface with a contoured recess lAa. Although not shown in the drawing, the upper shaping die 1B is formed at its lower surface with a contoured bulge which is shaped to mate with the contoured recess lAa of the lower shaping die 1A.

The lower and upper shaping dies 1A and 1B have each a heater embedded therein. The upper shaping die 1B is moved by a power mechanism (not shown), so that the upper shaping die 1B can be neatly put on and pressed against the lower shaping die 1A.

The lower shaping die 1A is formed with a plurality of gas discharging holes 2 each piercing through the die 1A from the shaping surface to the outer surface.

For production of the ceiling board 10, the heater in each shaping die 1A or 1B is energized to heat the die to a certain temperature. Then, a plastic-impregnated preformed substrate (not shown) is put on the upper surface of the lower shaping die IA. The substrate is a corrugated cardboard or a laminated felt board, which is impregnated with a thermosetting resin such as phenol resin or the like. One conventional corrugated cardboard comprises a corrugated base paper and a liner paper which are bonded by a hot melt adhesive. After the substrate is properly put on the lower shaping die lA, the upper shaping die 1B is moved down at a given speed and pressed against the lower shaping die 1A having the contoured bulge thrust into the contoured recess lAa,compressing the substrate therebetween. The upper shaping die 1B is kept pressed against the lower shaping die 1A by a given force for a given time. With this process, the substrate is molded to the shaped ceiling board 10.

During the molding process, any moisture and organic solvent in the substrate are vaporized or gasified due to the heat given by the heaters in the dies 1A and 1B. The gas thus produced is discharged to the outside through the gas discharging holes 2. With this gas discharging, undesired adhesive peel-off phenomenon in the substrate is suppressed.

However, forming the shaping die 1A with a plurality of gas discharging holes 2 not only needs a troublesome piercing technique but also affects or lowers the mechanical strength of the die 1A by a marked degree. In fact, if the number of the holes 2 is reduced with a view to maintain the mechanical strength of the die 1A, satisfac'-,ory gas discharging can not be expected.

It would therefore be desirable to be able to provide a mold unit which is free of the above-mentioned drawbacks.

The present invention, in one aspect, provides a mold unit for molding a shaped object from a

substrate The mold unit comprises a first or lower shaping die having a contoured recess over which the substitute is adapted be set; a second or upper shaping die having a contoured bulge which is shaped to mate with the contoured recess. The upper shaping die is movable down onto the lower shaping die, having the contoured bulge thrust into the contoured recess, compressing the

substrate therebetween. The contoured recess is formed at its shaping surface with a plurality of grooves each terminating at edges of the lower shaping die to open the outside.

Preerred-feature and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a schematic perspective view of a mold unit according to the present invention; Fig. 2 is a sectional view of the mold unit of the invention under a condition wherein a plastic-impregnated preformed substrate is pressed by the mold unit; Fig. 3 is an enlarged sectional view of one gas discharging groove formed on a shaping die of the mold unit; Fig. 4 is a perspectiveview of a shaped ceiling board for a motor vehicle; and Fig. 5 is a view similar to Fig. 1, but showing a conventional mold unit.

Referring to Figs. 1 to 3, particularly Fig. 1, there is shown a mold unit 11 according to the present invention.

As shown, the mold unit 11 comprises lower and upper shaping dies lIA and llB. The lower shaping die llA is mounted on a base body 14.

The lower shaping die llA is formed at its upper surface with a contoured recess llama. As can-be seen from figure 2 the upper shaping die 11B is formed at its lower surface with a contoured bulge which is shaped to mate with the contoured recess 11Aa of the lower shaping die llA. The lower and upper shaping dies llA and llB have each a heater embedded therein. The upper shaping die llB is moved by a power mechanism (not shown), so that the upper shaping die llB can be neatly put on and pressed against the lower shaping die llA in the same manner as in the case of the above-mentioned conventional mold unit 1.

In the present invention, the following measure is further employed, which can eliminate the above-mentioned drawbacks of the conventional mold unit 1.

That is, as is seen from Fig. 1, the shaping surface 12 of the contoured recess 11Aa of the lower shaping die lIA is formed with a plurality of parallel grooves 13 each extending to lateral sides of the die llA, as shown. These grooves 13 serve as the gas discharging means. The width "W" (see Fig. 3) of each groove 13 is about 2 mm, and the depth "D" of the groove 13 is about 1 mm.

The grooves 13 are arranged at equally spaced intervals "L", preferably, of about 150 mm to about 200 mm.

For production of the ceiling board 10 of Fig. 4 from a plastic-impregnated- corrugated cardboard 10a, the heaters in the shaping dies 11A and 11B are energized to heat the dies to a given temperature, for example about 130 C.

Then, the corrugated cardboard 10a is put on the upper surface of the lower shaping die 11A.

Then, the upper shaping die 11B is moved down and pressed against the lower shaping die 11A, compressing the corrugated cardboard 10a therebetween. The upper shaping die 11B is kept pressed against the lower shaping die llA for a given time in such a manner as is seen from Fig.

2. After the given time, the upper shaping die 11B is moved upward, releasing the lower shaping die 11A. Then, the product, that is, the shaped ceiling board 10, is removed from the mold unit 11.

During the molding process, any moisture and organic solvent in the substrate 10a are vaporized or gasified due to the heat applied thereto from the heaters in the dies llA and 11B.

However, the gas thus produced is smoothly discharged to the outside of the mold unit 11 through the gas discharging grooves 13.

In order to find out the best construction of the mold unit 11, the inventors have carried out many tests. According to these tests, the inventors have found that when the depth "D" of each groove 13 is 1 mm and the width "W" of the groove 13 is smaller than 1 mm, an undesired adhesive peel-off phenomenon tends to occur, and when, with the same depth, the width 'I "W" is greater than 6 mm, the substrate 10a may not be subjected to a uniform pressure by the mold unit 11. According to the tests, the inventors have further found that when the width 11W of each groove is 2 mm and the depth "D" is at least 1 m.., the gas discharging is smoothly carried out.

Thus, it is preferable for each groove 13 to have the width "W" ranging from 1 mm to 5 mm and to have the depth "D" greater than 1 mm, preferably ranging from 1 mm to 3 mm when considering the mechanical strength of the mold unit 11.

In the following, advantages of the mold unit 11 described above will be described.

First, the grooves 13 can be machined easily as compared with the holes 2 of the abovementioned conventional mold unit 1. That is, the mold unit 11 of the invention can be produced economically.

Second, since each groove 13 extends continuously on the shaping surface 12 from one lateral side of the die 11A to the other lateral side, any gas produced from the substrate 10a can be easily or instantly trapped by the groove 13, which induces smooth gas discharging to the outside of the mold unit 11.

Third, since the gas discharging grooves 13 are formed on only the shaping surface 12 of the die llA, the mechanical strength of the die 11A is not substantially affected.

In the following, modifications of the abovedescribed unit will be described.

If desired, in addition to the grooves 13, another group of grooves may be formed on the same shaping surface 12, which extend perpendicular to the grooves 13 to cross the same.

If desired, beside the lower shaping die 11A, the upper shaping die TiB may be formed on the bulged shaping surface with a plurality of gas discharging grooves like the grooves 13.

Claims

CLAIMS: -

1. A mold unit for molding a shaped object from a substrate, comprising: a first shaping die having a shaping surface with a contoured recess over which the substrate is to be placed, and a second shaping die having a shaping surface with a contoured bulge which is shaped to mate with the contoured recess, the shaping dies being relatively movable towards each other so that the contoured bulge is thrust into the contoured recess, for compressing the substrate therebetween, the shaping surface of one shaping die having a plurality of grooves, each terminating at edges of the shaping die open to the outside.

2. A mold unit as claimed in claim 1, in which the said grooves are parallel with one another.

3. A mold unit as claimed in claim 2, in which the parallel grooves are arranged at equally spaced intervals.

4. A mold unit as claimed in claim 3, in which the parallel grooves are arranged at intervals of about 150 mm to about 200 mm.

5. A mold unit as claimed in any preceding claim1 in which each groove has the width of about 1 mm to about 5 mm and has the depth of about 1 mm to about 3 mm.

6. A mold unit as claimed in any preceding claim, in which the shaping surface has two groups of grooves which cross each other.

7. A mould unit as claimed in any preceding claim, in which the said grooves are provided in the first shaping disc.

8. A mold unit as claimed in claim 7, in which the shaping surface of the second shaping die also has a plurality of grooves, each terminating at edges of the second shaping die open to the outside.

9. A mold unit as claimed in any preceding claim, in which at least one of the shaping dies has a heater embedded therein.

10. A mold unit as claimed in any preceding claim, in which the first shaping die is a lower shaping die and the second shaping die is an upper shaping die.

11. A mold unit substantially as described with reference to, and as shown in, figures 1 to 3 of the accompanying drawings.