JPS6157551B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for drying various thin wood boards, so-called veneer veneers (hereinafter simply referred to as veneers), which are cut with a wood peeling machine such as a veneer lace slicer. The purpose is to improve the quality and yield of extremely expensive decorative veneers or general plywood veneers that are handled in large quantities by preventing shrinkage cracks that occur as a result of drying.

Conventionally, there are various methods for drying these veneers, such as a well-known method of blowing hot air, a method of bringing a hot plate into contact with the veneer, and a method based on the principle of a microwave oven.
In any case, as the veneer shrinks as it dries, cracks occur at unexpected locations, leading to a decline in quality and yield.

That is, as is known, when a veneer is dried without being restrained, the veneer becomes noticeably wavy as it shrinks.
Since the quality would be extremely degraded and it would be almost impractical, it is customary to restrain and dry the veneer using the weight of the roll or the weight of the wire mesh, etc. The so-called ironing effect is used to flatten the veneer, but
On the other hand, when restrained in this way, frictional force is generated between the member and the veneer, inhibiting shrinkage, making it inevitable that cracks will occur, resulting in a decrease in quality and yield due to cracks. It has been extremely difficult to properly dry particularly soft decorative veneers.

The present invention makes it possible to arbitrarily limit the magnitude of the overall frictional force, including that caused by the weight of the veneer, with a simple configuration, thereby preventing the occurrence of cracks due to shrinkage, The purpose is to improve quality and yield, and the principle will first be explained based on illustrative drawings.

In the principle explanatory diagram illustrated in FIG. 1, 1 is a veneer, 2 and 2' are restraining members that restrain the veneer 1, and when the veneer 1 starts to shrink as it dries, the restraining members 2 and the dead weight of veneer 1, and veneer 1
In relation to the coefficient of friction between the veneer 1 and the restraint members 2, 2', a frictional force is naturally generated between the veneer 1 and the restraint members 2, 2', and stress is generated inside the veneer 1 as a reaction. , cracks occur in the veneer 1 due to stress concentrating on fragile parts, etc., but if, for example, the restraining members 2, 2' and the veneer 1 are allowed to fall freely as they are, geometrically Although the veneer 1 was restrained by the restraining members 2 and 2' in order to control the occurrence of waving, the veneer 1 floated in the air, like a person in an elevator whose rope had been cut. Due to the state of the force relationship, the source of frictional force is cut off, so that contraction is no longer inhibited, and as the contraction occurs, the stress is also eliminated.

The present invention periodically causes a change in the force relationship as described above, and specifically, applies vibration including motion having acceleration in the direction of gravity to all members that restrain the veneer, and By intermittently releasing or reducing the overall frictional force, including that caused by its own weight, we can reduce the stress that would eventually lead to cracking if it were to increase sequentially as before. It is used to intermittently consume the effect of shrinking the veneer to eliminate it, prevent its accumulation and concentration, and prevent the occurrence of cracks. The rate of contraction of the plate was surprising, and it was possible to release the stress each time by repeating the movement of free falling over a distance of just a few millimeters in a moderate cycle.

Of course, in view of the principle, it is best for the vibration to include motion (i.e., free fall) with an acceleration equivalent to the gravitational acceleration (9.8 m/Sec ² ) in the direction of gravity, but even if the vibration is less than the gravitational acceleration. It has been confirmed through experiments that it is possible to reduce the frictional force even when the motion involves motion with an acceleration of , or more, and is sufficient to reduce the occurrence of cracks.

Furthermore, as is well known, when the moisture content of veneer reaches approximately 30%, shrinkage tends to become noticeable. It has also been confirmed that it is sufficiently effective to start vibration or increase the vibration frequency from that time or location.

As described above, the drying method according to the present invention mechanically releases or relieves the restraint of the veneer, which is generally in a geometrically restrained state, at the appropriate time to prevent the occurrence of cracks. This structure is effective not only for drying general plywood veneers but also for drying soft decorative veneers, etc., which have been extremely difficult to dry properly in the past.

Hereinafter, the present invention will be described in detail along with an example of implementation illustrated in the drawings.

The single-stage hot press type drying apparatus illustrated in FIGS. 2 and 3 includes a restraining member 2 for restraining the veneer 1,
2' is a hot plate heated by a suitable heating means, and is supported by a connecting rod 3 connected to a shaft 4, which has a particularly excellent ironing effect.

For example, in a drying device configured as described above, a third
After carrying in the veneer 1 as shown in the figure, the shaft 4 is rotated at a constant speed or at an inconstant speed in the direction of the arrow shown in the figure as shown in FIG. If this is applied, the restraining member 2 and the veneer 1 are also vibrated, so the restraint due to vibration is released or relaxed, and the drying is effective while suppressing the occurrence of waving and preventing the occurrence of cracks. can be done.

Incidentally, if a one-way clutch or the like is interposed between the drive source of the shaft (not shown) and the shaft, free falling motion can be easily obtained, but as a mechanism for imparting vibration, the above-mentioned mechanism It is not limited to this, for example, it is possible to apply vibrations using a cam mechanism using a plate cam, a structural cam, etc., and in short, a mechanism that can apply the desired vibration to all the members that restrain the veneer. If so, there is no problem.

In addition, the mode of vibration, for example, the period of vibration, the magnitude of acceleration, the duration of acceleration movement, etc., can be set appropriately depending on the conditions of the veneer. For example, if the number of vibrations is small, shrinkage cracks will occur. However, it is sufficient to narrowly limit the spread of cracks, so it does not pose much of a problem depending on the use of the veneer. However, the drying process of the veneer usually depends on the thickness, material, etc. of the veneer. Since it changes in various ways depending on the initial moisture content, etc., it is not necessary to limit the vibration mode fixedly, and the vibration mode can be varied based on mechanical or electrical control means. It is most convenient to configure it as follows.

Although not shown in the drawings, the drying apparatus was modified to be a so-called multi-stage hot press type drying apparatus, in which hot plates were stacked in multiple stages and, if necessary, an automatic veneer loading mechanism was added. Therefore, even if the hot plate is vibrated in the same way as in the above embodiment, the effect of releasing or relaxing the restraint due to the vibration is effective regardless of the number of stages of the hot plate, and is effective.・Even if a restraining force other than the weight of the hot plate is applied to the veneer through air pressure, etc., the vibration will effectively act on the weight of the hot plate and the veneer, so the result will be However, in any case, with such hot plate type drying equipment, ensuring sufficient contact with the veneer is advantageous in shortening the drying time. Needless to say, it is a good idea to make at least one of the hot plates that restrain the veneer somewhat flexible by aggregating a large number of small planes to improve contact with the veneer. is beneficial.

On the other hand, the drying device illustrated in FIG. 4 is a mobile type heating device consisting of a slat conveyor, a caterpillar conveyor, etc., in which one of the restraining members for restraining the veneer is made to travel via drive members 6, 6'. A plate 5 (heated to high temperature by an appropriate heating means) and a hot plate 8 supported by a cam 7 are used to improve the ease of loading and unloading the veneer 1.
Even in the drying device having such a configuration, by rotating the cam 7 in the direction of the arrow shown in the figure and vibrating the hot plate 8, effective drying can be performed while preventing the occurrence of cracks.

Also in the above embodiment, as the movable hot plate 5 and the veneer 1 vibrate with the vibration of the hot plate 8, friction due to the weight of the movable hot plate 5 and the veneer 1 is caused. Since the generation of force is eliminated or reduced, there is no need to vibrate the entire device including the bed 9 that holds each member. Furthermore, as is clear from this, the effect of vibration is the source of frictional force generated by the veneer's own weight, regardless of whether there is a member restraining the veneer from above. Even without this, it is clear that it is sufficiently effective to apply vibration to the member that restrains the veneer from below.

In addition to the drying apparatus of each of the above embodiments, the drying method according to the present invention can be applied, for example, to a (veneer veneer drying apparatus) (Japanese Patent Publication No. 49-35121) or a "continuous plywood manufacturing apparatus" ( It is possible and effective to implement the heating device of the type disclosed in Japanese Patent Publication No. 49-32051 (Japanese Patent Publication No. 49-32051), as well as well-known roll dryers, net dryers, etc.; Vibration that includes free-falling motion is effective, and it is also equally effective to start vibration or increase the frequency from the time or location when the moisture content of the veneer reaches around 30%. It is clearly stated that this is as stated in the explanation of the principle above.

[Brief explanation of the drawing]

The drawings are for explaining the present invention, and FIG. 1 is a principle explanatory diagram for explaining the drying method according to the present invention, and FIG. 2 is a diagram showing the drying apparatus used to carry out the drying method according to the present invention. 3 is an explanatory side view of the drying apparatus illustrated in FIG. 2, and FIG. 4 is an explanatory front view of another drying apparatus used for carrying out the drying method according to the present invention. DESCRIPTION OF SYMBOLS 1...Single plate, 2, 2'...Restriction member, 3...Connecting rod, 4...Shaft, 5...Movable hot plate, 6, 6'...Driving member, 7...Cam, 8 ……
Hot plate, 9... bed.

Claims (1)

[Scope of Claims] 1. A method for drying a veneer veneer, characterized in that drying is performed while applying vibrations including motion having acceleration in the direction of gravity to all members that restrain the veneer veneer. 2. The method for drying a veneer veneer according to claim 1, which comprises vibration including free-falling motion. 3. The method for drying a veneer veneer according to claim 1 or 2, which comprises starting vibration or increasing the frequency of vibration when the veneer reaches a moisture content of approximately 30 percent.