JPH0623708A - Method for molding wood sheet - Google Patents

Abstract

PURPOSE:To easily mold a thin wood sheet like veneer into an arbitrary shape within a short time. CONSTITUTION:A wood sheet 16 preliminarily increased in water content to be heated is pressed by a hot press device mounted through perforated molds 5,6 and a vacuum suction plate 11 and, thereafter, the molds are evacuated through the vacuum suction plate 11 to dry the pressed product up to predetermined water content under vacuum. The perforated molds are produced from a metal or ceramic sintered member obtained by sintering a powder molded member formed by a slip casting method wherein the moisture of slip is absorbed into a gypsum mold. Therefore, a wood sheet molded product having an arbitrary shape is produced with high productivity using an inexpensively and easily produced mold and laminated to a surface to produce a grain like part for car or household electric product having a high-grade feeling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a wood sheet generally called a veneer and having a thickness of about 0.2 to 1 mm, and more particularly to this press forming method.

[0002]

2. Description of the Related Art Conventionally, decorative plywood having a veneer made of beautiful wood such as teak, karin, wall nut, taro and the like has been widely used for furniture and building materials.

Recently, however, wood-grained parts have been used in the fields other than furniture and building materials such as automobiles and home appliances such as automobiles, home appliances, etc. I'm getting more and more feeling.

As wood grain parts have come to be used in a wide variety of fields in this way, veneer plates can be used not only for flat plate-like products such as conventional decorative plywood but also for various shapes with curved surfaces. I have to put it.

When sticking a veneer on a curved surface and the degree of curvature is small, it is sufficient to fix the flat veneer while deforming it following the curved surface and then fixing it in that state. If the degree of is large, the veneer plate will be cracked, so the veneer plate must be formed in advance into the same shape as the pasting surface by press molding and then pasted.

[0006] In the conventional press forming of a veneer, a water content of about 15 to 25% is used to facilitate deformation and then 100 to 100%.
First, the veneer is made to have plasticity by heating to about 150 ° C.

Next, the veneer plate having this plasticity
It is attached to a mold preheated to about 0 ° C, press-molded, cooled to room temperature, taken out of the mold, and dried in a drying chamber at about 60 to 70 ° C to a water content of about 10 to 12%. Obtain a molded product.

[0008]

However, in the conventional molding method, it takes a very long time to dry, and
Since the drying has to be performed using a jig for preventing deformation, the productivity is poor and it is not suitable for mass production.

That is, in the conventional method, when a press-molded molded product is taken out of the mold and dried, if it is put in the drying chamber as it is, it will be deformed. Therefore, it is necessary to first attach it to the jig and then put it in the drying chamber. It was

Therefore, in the case of mass production, a large number of jigs must be prepared, which is costly and requires a lot of man-hours for mounting.

Next, when the water is evaporated rapidly by drying to evaporate the water, cracks are formed in the curved surface.
Moisture content of 1 over 3 days at relatively low temperature
From 5 to 25% to 10 to 12%,
It takes a very long time.

The present invention solves the above-mentioned drawbacks of the prior art, and provides a method for molding a wood sheet suitable for mass production, which enables to obtain a molded product of good quality with high productivity. To aim.

[0013]

That is, according to the present invention, a porous press die in which a heater and a cooling pipe are embedded is attached to a press device through a vacuum suction plate, and a plastic material is preheated to a molding temperature with a high water content. The given wood sheet was attached to the above-mentioned press machine and hot-pressed, the molded product was cooled to room temperature while being held in the mold, and then heated again to the drying temperature, and at the same time, the mold was evacuated and dried, and the drying was completed. A molding method of a wood sheet, which is characterized in that the molded product is cooled to room temperature and then taken out from the mold, and further, the porous press mold is a plaster mold in which the product shape is modeled, and metal and / or ceramic powder sludge. Manufactured from a metal and / or ceramic sinter that is formed by sintering a powder compact by the slip casting method in which water in the slurry is poured and dehydrated in a plaster mold. A method of forming a timber sheet characterized by being molded on the basis of the above-described process.

[0014]

The present invention is constructed as described above, and uses a porous mold as a mold for molding, and since this mold is mounted on the press device through a vacuum suction plate, a press molded product is obtained. Vacuum drying can be performed while holding it in the mold.

When the molded product is dried while being held in the molding die, there is no need to prepare a drying jig or attach or detach the molded product to or from the jig. At the same time as being absorbed by the porous mold, it is evacuated and removed to enable drying in a very short time of about several tens of minutes.

Further, the mold used for molding can be easily manufactured at a low cost by molding the surface shape of the master model of the product shape by the slip casting method using the slurry of the metal and / or ceramic powder, and the metal and / or Since it is made of a ceramic sintered body, it has sufficient porosity for vacuum-drying a molded product, and also has excellent heat resistance and durability.

[0017]

EXAMPLE An example of the present invention will now be described with reference to the drawings. FIG. 1 shows a molding state of a wood sheet based on the molding method of the present invention, and 1 is a press device having a hydraulic device 4, 2 is the upper platen for mounting the fixed mold, 3
Is a lower platen for mounting a movable die which is vertically driven by the hydraulic device 4.

A heater 5 is made of, for example, a stainless sintered body.
And an upper die (punch) in which the cooling pipe 8 is embedded, and 6 is a lower die (die) in which the heater 7 and the cooling pipe 8 are embedded, which are also made of a stainless sintered body. Although not shown, of course, a temperature sensor for controlling the mold temperature is also embedded.

The above-mentioned upper and lower molds 5 and 6 are mounted on the upper and lower platens 2 and 3 via a rear heat insulating sheet 10 and a vacuum suction plate 11 which are fitted in an aluminum alloy frame 9 for sealing the side surfaces.

As shown in FIG. 3, the vacuum suction plate 11 is a metal whose surface is provided with a continuous vacuum suction groove 12 having a predetermined depth and whose side surface is provided with a vacuum suction hole 13 connected to the vacuum suction groove 12. It is a plate.

Reference numeral 14 is a vacuum suction pipe having one end connected to the vacuum suction hole 13 of the vacuum suction plate 11 and the other end connected to the vacuum pump 15.

16 is a wood sheet to be molded, and for example, a plate with a teak material having a thickness of 0.3 mm is first used for 25 to 30
After setting the water content to% k, for example, with a microwave heating device,
It was previously heated to 0 to 140 ° C.

As described above, heating the wood sheet to a high water content before forming is performed by lignin, which is the main component of wood,
This is because when hemicellulose is heated to about 70 to 140 ° C. in a wet state, it has increased plasticity and is easy to mold.

The above-mentioned wood sheet 16 which has been raised in water content and heated to the forming temperature in advance is placed on the lower mold 6 of the press machine 1 which is preheated to 100 to 120 ° C. by the heater 7 in which the upper and lower molds 5 and 6 are embedded. Put.

After that, the lower die 6 is moved upward by driving the hydraulic device 4 and sandwiched between the upper and lower dies 5 and 6 of the wood sheet 16, and press-molding while maintaining a pressure of 15 to 30 kgf per square cm for about 5 minutes. Then, the following operation is carried out while holding the molded product under this pressure.

First, the heater 7 in which the upper and lower molds 5 and 6 are embedded is turned off, and cooling water is flown through the cooling pipe 8 to about 30.degree.
It is cooled to 10 minutes, and this state is maintained for 10 minutes to form a complete molded product that does not return to its original shape.

After that, the cooling water is stopped from flowing through the cooling pipe 8 in which the upper and lower molds 5 and 6 are buried, and the heater 7 heats it again to about 100 ° C., and in this state, the vacuum pump 4 is operated to perform vacuum suction. The mold is evacuated through the plate 11 and the molded product is vacuum dried.

This vacuum drying is carried out until the water content reaches about 10%, and the time required for this is determined in advance by experiments.
Usually, it takes about 10 to 30 minutes.

As described above, the reason why drying is possible in a short time is because the molded product is held under pressure in a porous mold and vacuum-dried, so that the moisture in the molded product is absorbed by the porous mold. At the same time, it is evacuated so that it can be removed very quickly.Moreover, even if such a rapid drying is performed, the molded product is still held in the mold so that it does not deform and only the surface is quickly removed. Does not dry and crack.

When the drying is completed, the upper and lower molds 5 and 6 are cut off by turning off the heater 7 and the cooling water is flown again through the cooling pipe 8 to cool it to 50 ° C. or lower.
Is operated to move the lower mold 6 downward to open the mold and take out a molded product 17 having a greatly curved concave portion 18 as shown in FIG.

Next, a method of forming a metal and / or ceramic sintered body mold as a porous mold used for the above-mentioned molding will be described.

First, the surface shape of a master model of a product shape formed of a material such as plastic or wood that is easy to process is used to mold a surface of the master model 20 as shown in FIG. Prepare a plaster mold 19 to hold.

On the other hand, a metal and / or ceramic powder forming a mold and a dispersant are mixed with water, for example, 35% by weight of SUS304 powder having an average particle size of 40 to 100 μm,
A slurry 21 containing 2% by weight of ammonium alginate and the balance of water is prepared.

Next, as shown in FIG. 4, the above-mentioned sludge 21 is poured into the cavity 20 of the gypsum mold 19 and then left for about one day and night to allow the gypsum mold 19 to absorb the water in the sludge 21 to form a molded body. obtain.

In this case, the gypsum mold 19 needs to have a volume capable of completely absorbing the water in the slurry 20, and the cavity 20 has a cooling pipe and a heater embedded in the mold formed therein. Needless to say, deploying.

Once the water is removed from the slurry 21 into the plaster mold 19 to obtain a molded product having the shape of the cavity 20, the molded product is extracted from the gypsum mold 19 and the molded product is a dispersant. Since the SUS powder is bound by ammonium alginate as described above, it does not disintegrate.

Thereafter, the molded body taken out is left to stand at room temperature for several days to be naturally dried, or forcedly dried at 40 ° C. for about 6 hours, depending on its shape and size.

The dried molded body is placed in a vacuum furnace and
Sintering was performed at 350 ° C. for 8 hours to obtain a stainless sintered body having a porosity of about 7.5%, and the sintered body was machined as necessary such as planing the bottom surface, and the heater 23 as shown in FIG. Further, the press die 22 made of a stainless sintered body in which the cooling pipe 24 is embedded and the temperature sensor hole 25 is provided is obtained.

The porosity of the press die 22 described above can be easily changed by adjusting the particle size and mixing ratio of the stainless powder of the slurry.

Although the mold is made of stainless steel powder in the above-mentioned embodiments, other metal powder, ceramic powder, or a mixed powder of both may be used if necessary.

[0041]

Industrial Applicability The present invention has the above-described structure and operation, and the wood sheet can be molded in a short time by continuously performing hot press molding and vacuum drying in a state where it is mounted in the press machine.

As a result, it becomes possible to mold a veneer of beautiful wood with a high productivity into an arbitrary shape, and to mount parts of various industrial products such as automobiles, home appliances and the like, which are mass produced, on the surface of the molded product. By sticking it, you can easily give it a high-quality grainy look.

Further, the porous press die used for this molding is easily and inexpensively produced as a metal and / or ceramic sintered body having an arbitrary porosity by the slip casting method and excellent heat resistance and mechanical properties. Can be made with.

[Brief description of drawings]

[Figure 1] Molded state,

[Fig. 2] Vacuum suction plate,

[Figure 3] Molded product,

[Fig. 4] Mold manufacturing state,

FIG. 5 Mold.

[Explanation of symbols]

 1 Pressing Device 2 Upper Platen 3 Lower Platen 4 Hydraulic Device 5 Porous Upper Mold 6 Porous Lower Mold 7 Heater 8 Cooling Pipe 9 Metal Frame 10 Heat Insulating Material 11 Vacuum Suction Plate 15 Vacuum Pump 16 Wood Sheet 17 Molded Product 18 Recess 19 Gypsum Mold 21 Sludge 22 Porous press mold

Claims (2)

[Claims] 1. A porous press die, in which a heater and a cooling pipe are embedded, is attached to a pressing device via a vacuum suction plate, and a wood sheet which has been heated to a forming temperature in advance with a high water content to give plasticity to the pressing device. After mounting, heat pressing, cooling the molded product to room temperature while holding it in the mold, then heating it again to the drying temperature, vacuum evacuation of the mold to dry, and cooling the dried molded product to room temperature. A method for forming a wood sheet, which is characterized in that the wood sheet is taken out of the container. 2. A powder compact by a slip casting method in which the porous press die injects metal and / or ceramic powder sludge into a gypsum die having a product shape, and dehydrates water in the sludge with the gypsum die. The method for forming a wood sheet according to claim 1, wherein the wood sheet is manufactured based on a metal and / or a ceramic sintered body formed by sintering.