JPS60116405A - Method of bending woody synthetic board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention involves bending an already formed wood composite board such as fiberboard or particle board to a small radius of curvature by applying high frequency and pressing it with relatively low pressure. It is about the method.

There have been various methods for bending wood composite boards such as wood fiberboard and particle board.
(hereinafter referred to as "board") has different properties from metals and plastics, so those that are bent are inferior in terms of mechanical strength and physical properties compared to those made into a flat plate. There were many things.

One way to make a bent board have almost the same mechanical strength and physical properties as a board made into a flat board is to apply appropriate treatment to the mantle in the previous process of the board to be made into a flat board. Instead, there is a method of forming curved boards, and various techniques are known, but this method requires a consistent production line for boards, so it lacks versatility, and it can also be molded into a variety of shapes. In order to manufacture curved plates of different dimensions, it is necessary to have molds of various shapes, which makes it extremely uneconomical and has hardly been realized.

Therefore, various methods have been tried for bending flat boards that have already been formed, but the conventional methods do not involve applying a large amount of moisture or softening/penetrating agents to the bent part of the board during bending. The surface smoothness of the board that has already been formed has been significantly damaged due to the addition of a solvent with added or heating at high temperatures for a long period of time along with these treatments, and the bent portion of the board has been significantly damaged. However, the mechanical and physical strength of the material is significantly reduced.

Of course, in order to minimize the decrease in surface smoothness and strength of curved surfaces, we reduced the amount of the above-mentioned solvent used.
Although it is possible to reduce high-temperature heating, this requires long-term and high-pressure clamping, which causes more damage to the board during bending and significantly reduces the yield of bending. was there.

By the way, when it comes to fiberboard, it is possible to reduce the internal bonding force by re-pressing the fiberboard with relatively low specific gravity (specific gravity of 0.15 to 0.4) to reduce the internal bonding force and increase the flexibility, and to create many scratch grooves and grooves on the surface. It is already known that micropores are created to lower the rigidity of the fiberboard to make it easier to bend, and then the fiberboard is bent. The disadvantage is that it requires the addition and application of an adhesive, etc., which significantly increases the manufacturing cost.

The present invention solves the above-mentioned drawbacks and problems and provides a method for bending an already formed flat board to a smaller radius of curvature. After inserting the board between the electrode plates and preheating it by applying high frequency without applying pressure, the board is lowered in rigidity by an appropriate suppressing means.
．． Apply high frequency to a non-conductive shape material that has the desired bending shape using a pressing force of about 5 to 3 kg/ca, and bend the board while applying high frequency. After the board is in close contact with the shape material, the same pressure force is used to bend the board. In this method, a high frequency is applied to the board and then pressing is continued to obtain a bent board with a relatively small radius of curvature.

The moisture content of this board may be kept at the equilibrium moisture content, but of course, the higher the moisture content, the shorter the high frequency application time.

Incidentally, after the bending process, while the board heated by high frequency is cooled to room temperature, it may be bent using a simple method.

The surface smoothness and mechanical and physical strength of the board subjected to bending in this manner were almost the same as those before bending.

Next, examples of the present invention will be shown together with figures.

The board to be bent has the following specifications.

Type: Medium specific gravity fiberboard.

Thickness: 7 cranes Dimensions: Length: 500 m, Width: 600 m++.

Specific gravity i 0.60 Moisture content: 10% Two electrode plates 2 and 3 for high frequency application made of copper thin plates or aluminum thin plates having slightly larger dimensions are placed on the upper and lower surfaces of the board 1 having the above specifications, and These are placed on a stainless steel pressing plate 5 via a suitable non-conductive cushioning material 4.

Next, output terminals 7 and 8 of a separately provided high frequency generator 6
The rigidity of the board 1 is reduced by connecting the electrode plates 2 and 3 and applying a high frequency to the board 1 and performing a preliminary treatment for about 1 to 5 minutes.

The applied high frequency oscillation frequency is 10MHz to 15MHz
It is 2.

Note that at this preheating stage, it is sufficient that the electrode plates 2 and 3 are in contact with the board 1, and there is no need to apply any pressure.

Next, the board 1 sandwiched between the electrode plates 2 and 3 is placed against a semicircular shaped material 10 with a radius of curvature of about 200 mm, which is fixed to the frame 9 and is made of a non-conductive material (hard water, hard plastic, etc.). is pressed by means described below.

This pressed state is indicated by a dotted line in the figure.

Clamping pressure during pressing is 0.5 kg/c ~ 3 kg/c
In this example, the mold material 1
The presser plate 5 on the side that does not come into contact with 0 is made of stainless steel N (thickness i
A chain or wire 11.11" is attached to each end of the chain or wire 11.11" as a chain or wire 11.11" (approximately 3.5"), and this chain or wire 11.11" is wound up and held down by a winder 12.12" provided on the top of the frame 9. The board 5 is raised together with the board 1, the electrode plates 2 and 3, and the cushion material 4, and the board 1 is pressed against the mold material 10.

It goes without saying that the two winders 12, 12'' are driven in a balanced manner by appropriate driving means (not shown).

This pressing time varies depending on the type and thickness of the board 1, but in this embodiment, it is 2 to 3 minutes.

The high frequency applied during this pressing is the same as that during the preliminary treatment, and the conditions are as follows.

Input power: AC200/220V High frequency output: 3Kw Oscillation frequency: 10MHz = 15MHz After the pressing time is over, cut off the high frequency of the electrode plates 2 and 3, then rewind the chain or wire 12 and 12 degrees and lower the presser plate 5. It is sufficient to take out the board 1 that has been bent.

The board heated by high frequency waves may be stamped in a predetermined cent shape (any simple shape may be used) before being cooled down to room temperature.

The board l bent as described above was heated to 40°C - 8°C.
It was allowed to absorb moisture with 0% til+ for 5 hours, then left to stand naturally for 19 hours, and then dehumidified and dried at 40℃-40% R11 for 5 hours, but the length of the arc chord changed only by about 1% before and after the experiment. But it wasn't.

Further, no deformation such as cracks, fluff, wrinkles, etc. was observed on the back surface, which is the inner peripheral surface, or the outer peripheral surface of the bent surface.

The method of the present invention is not limited to the above-described embodiment in which the board 1 is a medium-specific gravity fiberboard, but can also be applied to particleboards, but since particleboards generally have greater rigidity than fiberboards, the radius of curvature during bending may be somewhat smaller. It has to be bigger.

Furthermore, the shape to be bent is not limited to a semicircle, but can be made into various shapes by changing the shape material 10, as illustrated in FIG.

However, the minimum radius of curvature of the curved surface part to be bent is 100
tm (for fiberboard with a thickness of 5.5 mm).

Furthermore, although this example shows an example in which one board is bent, two or more boards can be bonded using vinyl acetate/urea resin adhesive or phenol resin adhesive adjusted with a curing retardant as appropriate. If the board is laminated with a pretreatment agent and then pressed against the shape material, the dimensional stability after bending will be significantly improved compared to when bending a single board. The clamping force at 3 to 5 kg/
Since it is necessary to make the bending process as high as cJ, it is necessary to make the bending device more robust.

It should be noted that the device according to the embodiment of the present invention is only one means of pressing for bending, and any device that uniformly generates the clamping pressure during pressing defined by the present invention on the surface of the board may be used. Any method is fine.

Next, we prepared a medium-density fiberboard flat plate, which is the same board as in the above-mentioned example, with a veneer attached and a PVC sheet attached in advance, and a decorative groove with several parallel grooves cut on one side of the flat plate. The board was bent in the same manner as in the above example.

In all cases, no deformation such as cracks, fluff, wrinkles, etc. was observed on the bent surfaces of the veneer panel, the PVC sheet panel, and the parallel grooved surface.

Moreover, the dimensional stability after bending was similar to that of a medium-density fiberboard which was not subjected to any secondary processing such as pasting with a veneer or grooving when it was flattened.

The method of the present invention described above does not reduce the surface performance of the flat board that has already been formed, that is, there is no occurrence of cracks, fluff, wrinkles, etc. on the bent surface, and of course the mechanical strength is also improved. This makes it possible to bend boards with a small radius of curvature without reducing the radius of curvature.

Furthermore, the bending method using the low pressing force of the present invention allows flat boards that have been subjected to secondary processing to be grooved or have veneers attached to them to be bent without damaging the surface of the secondary processing. This has the extremely advantageous industrial advantage of being able to do so.

1. In other words, conventionally, secondary processing of bent boards was extremely difficult and therefore very expensive, but the method of the present invention allows secondary processing to be performed using inexpensive flat secondary processing boards. Bending boards can now be obtained at low cost.

Furthermore, since the method of the present invention enables bending with a low pressing force, the yield loss in the thickness direction, which tends to occur with boards made of wood composite boards, has become extremely small, and the double-sided mold necessary for high-pressure clamping has been made possible. The method of the present invention has excellent effects, such as eliminating the need for bending of various shapes and dimensions and making it possible to handle bending processes of various shapes and sizes at an extremely low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the method of the present invention,
1 is a board to be bent (-wood composite board), 2.
3 is an electrode plate, 4 is a cushioning material, 5 is a holding plate, 6 is a high frequency generator, 7 and 8 are high frequency output terminals of the high frequency generator, 9 is a frame, 10 is a shape material for bending the board, 11. 11゛2 is a chain or wire, 12.12゛ is a chain or wire winding machine. (A), (B), (C), and (D) of FIG. 2 are cross-sectional views of boards (=wood composite boards) bent by the method of the present invention. Applicant for the above patents: Sakae Yamaguchi, representative director of Mikaita Co., Ltd. 3 (a) (0) (c) (d) Figure 12

Claims (1)

[Claims] 1. When bending a wooden composite board such as fiberboard or particle board that has already been formed into a flat plate while keeping its equilibrium moisture content, two First, a high frequency is applied using two electrode plates to perform a preliminary treatment, and then a high frequency is applied to a pre-prepared molded material having a curved surface of the desired shape.
A method for bending a wood composite board, which is characterized by pressing at a relatively low pressure of kg/cd to obtain a wood composite board with a curved surface. 2. A wooden composite board formed into a flat plate is pasted with a veneer or a decorative sheet in advance. 3. Surface grooves are processed, or relief patterns are processed, etc., after which secondary processing is performed. First, a high frequency is applied to the wooden composite board using two electrode plates placed on the front and back of the board to perform a preliminary treatment, and then a high frequency is applied to a pre-prepared molded material having a curved surface of the desired shape. A method for bending a wood composite board, which is characterized by pressing at a relatively low pressure of 5 to 5 kg/c+a to obtain a wood composite board having a curved surface. 3. When pressing the wood composite board against the mold material while applying high frequency, a non-conductive cushioning material is provided on the outside of the electrode plate placed on the surface of the wood composite board that is not in contact with the mold material. Claims 1 and 2, characterized in that a flexible stainless steel holding plate is used.
Bending method for wood composite board as described in section.