JPS587156B2 - Obijiyoutanpanno Renzokukansouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for continuous drying of veneers in which a band-shaped veneer is unwound from a winding ball and transported as it is into a dryer for drying. The present invention relates to a continuous drying method for veneers in which a terminal end portion and a starting end portion of a veneer that is currently being rewound are conveyed one after the other into a dryer.

Typically, band-shaped veneers are obtained by continuously cutting a log from its sapwood to its heartwood using a rotary race.

The veneer cut by this rotary race is then sequentially wound into a bobbin by a reeling device starting from the portion corresponding to the sapwood, and further conveyed on a reel deck, and then reversely processed by the unreeling device to the portion corresponding to the heartwood. The film is sequentially rewound and dried using a dryer.

During this drying process, the unwinding of the rolled balls is performed continuously, and it is not recommended to wait until all the veneers that have already been rewound have been dried by the dryer before starting the unwinding of the next rolled ball. Do not do this as it will result in energy loss.

Therefore, in the dryer that continuously dries these veneers, there is a terminal portion corresponding to the sapwood of the previously rewound veneer,
The starting end portions corresponding to the core of the veneer that is currently being unwound may be simultaneously dried in the dryer one after the other.

The veneer part corresponding to sapwood and the veneer part corresponding to heartwood are conveyed at the same speed in front and back in this dryer.
There is a difference of several tens of factors in the moisture content of each type, which causes problems in the conventional continuous drying method for drums.

Conventionally, this continuous drying of veneers has been carried out using a dryer in which conveyors for carrying in and out of veneers, which can synchronize the veneer transport speed with the veneer drying speed, are placed at the inlet and outlet sides, respectively. The moisture content of the veneer after drying is measured with a moisture content meter, and based on the moisture content calculated from this, the initial moisture content of the veneer that is currently being carried into the dryer is assumed, and feedback is used to determine the moisture content of the veneer in the dryer. Do this by adjusting the drying speed.

With this method, when drying between the leading and trailing ends of a single strip-shaped veneer, the moisture content does not change rapidly, but only changes gradually from a portion corresponding to the heartwood at the beginning to a portion corresponding to the sapwood at the end. Therefore, it can be taken care of.

However, in the conventional method, the end sapwood part of the veneer that is first rewound and progresses inside the dryer, and the beginning end sapwood part of the veneer that is then rewound and progresses in the dryer in contact with this, are Until all of the end sapwood of the previously rewound veneer is taken out of the dryer and passed through the moisture content meter, the starting core wood of the next veneer remains at the end of the veneer that was rewound first. It is dried at a rate based on the moisture content in the wood section.

At this time, since the moisture content of the starting corewood portion of the veneer is relatively several tens of times lower than that of the terminal sapwood portion of the veneer, the subsequent veneer portion becomes overdry during this time.

Conventionally, when this over-dried area occurs, it can cause cracks on the surface of the veneer or variations in product quality, so after drying the strip of veneer, it is removed by cutting it with a clipper that cuts it to a fixed size, and it is not used for products. Not yet.

Therefore, the present invention is capable of continuously drying both the end portion of the previously unwound veneer and the start end portion of the veneer that is currently being rewound to a permissible moisture content, which are successively fed into the dryer. The purpose is to provide a simple method.

The initial moisture content of the veneer varies depending on the species of the raw wood, the transportation and storage conditions, etc., and the degree of drying required for the veneer varies depending on the product's use, such as construction, crafts, furniture, etc.
The drying speed of the veneer is determined by the drying temperature in the dryer.
It varies depending on the length of the dryer.

Therefore, the following description based on the illustrated embodiments is intended to show one example of embodying the present invention.

The veneer rolls 1 are sequentially unwound onto a veneer transport conveyor 3 by an unreeling device 2 at a speed synchronized with the veneer transport speed, starting from those cut from the core of the log.

The veneer to be rewound is sequentially conveyed into the dryer 4 by the conveyor 3 from its starting end.

The conveyance speed is adjusted by a conventional method until the starting end of the veneer enters the dryer and the end end enters the dryer.

That is, when inserting the starting end part, the drying speed is set appropriately in advance, and after the starting end part of the veneer is dried, it is carried out backward from the dryer 4 by the carrying out conveyor 5, and when it reaches the moisture content meter, it is continued. From the section to the end section entering the dryer, drying is performed at a rate controlled by feedback based on the assumed moisture content determined from the moisture content of the veneer sections that have already been dried.

Under normal conditions, the moisture content of the veneer from the area corresponding to the heartwood of the log is around 25-40%, and the moisture content of the veneer from the area corresponding to the sapwood that follows this is around 60-75%. It has a moisture content of

For example, in order to dry this strip-shaped veneer to a moisture content of about 7 to 10%, the length should be approximately 50 to 60 m, and the drying temperature should be 140 to 140 m.
Using a dryer at 170℃, the speed is 20m/min at the beginning of the veneer and 16m/min at the end of the veneer.
It is necessary to perform drying at each drying speed of min.

Assuming that a roll of strip-shaped veneer that is suitable for this example is to be dried, the veneer transport speed of the dryer is set in advance to 20 m/min when drying the starting end, and then the drying of the veneer section that follows is In this process, the drying speed is controlled to gradually slow down using feedback from measurements of the moisture content of the dried veneer as it is carried out from the dryer, so that the drying speed reaches 16 m/min in the sapwood portion near the end.

In controlling the drying speed of the dryer 4, the conveyors 3.5 disposed on the inlet and outlet sides of the dryer 4 are simultaneously controlled so that the veneer transport speed is synchronized with the speed of the drying conveyor inside the dryer.

In this way, one continuous roll of strip-shaped veneer is rewound by the unrolling device 2, and when the next spool is unwound, a certain amount of pressure is applied from the rear end of the previously rewound veneer. Dimension l
A mark is applied to the surface of the veneer at the far end using a marking device 6 using, for example, colored ink or chalk.

And the rear end portion 1a of the veneer with this mark attached,
The starting end portion 1b of the veneer that is currently being rewound is moved forward and backward toward each other and is continuously conveyed into the dryer 4.

At this time, the rear end of the veneer, which has a moisture content of about 60 to 75%, and the start end of the veneer, which has a moisture content of about 25 to 40%, are both conveyed into the dryer. The drying speed of the dryer is 16 m/win, which is enough to dry the veneer from 60 to 75% moisture content to about 7 to 10%.

These veneers having different moisture contents are dried at a speed of 16 m/min relative to the previous veneer portion having a higher moisture content.

When the rear end portion of the previously rewound veneer is carried out of the dryer 4 by a certain distance l' by the carry-out conveyor 5 after drying, the mark previously made on the surface of the veneer is marked with, for example, a phototube or a limit switch. It is detected by a detection device 7 such as.

In response to this detection signal, the starting end of the veneer that is currently being rewound is automatically or manually controlled from a speed of 16 m/min for drying the rear end of the veneer that has been rewound. The drying speed of the dryer 4 is controlled to a drying speed of 20 m/min.

Then, when the starting end of the veneer processed at this drying speed is taken out of the dryer and measured by a moisture content meter, the drying speed of the subsequent veneer section is controlled using the conventional method. do.

In this way, the point in time when the veneer drying speed of the dryer 4 is controlled is when the mark made on the surface of the veneer ahead of the end portion of the previously rewound veneer is detected by the detection device 7, and the end of the veneer is detected by the detection device 7. The point in time is set such that a portion of the end portion remains in the dryer 4, and this remaining end portion is dried to the maximum allowable moisture content when it is subsequently carried out of the dryer.

For this purpose, the marking device 6 and the detection device 7 are positioned.

The permissible moisture content of this veneer is generally up to a maximum of 15%.

Therefore, in this specific example, when the part of the previously rewound veneer remaining in the dryer is transported out of the dryer, the dryer unit is dried at a position where its moisture content is reduced to 15%. Adjustments can be made to increase the board drying speed.

In this position, the veneer with a moisture content of 60 to 75% is
60m, drying temperature 140-170℃, drying speed 16m/
This is when the dryer is dried to 20% with a dryer at 100 m/min. From this point on, if the dryer's drying speed is changed to 20 m/min, the remaining veneer can be dried to a moisture content of 15%.

If the marking device 6 and the detecting device 7 are positioned based on this relationship, for example, when the marking device 6 is positioned at a position equal to the dryer length l from the rear end of the veneer that has already been rewound, the dryer exit of the detecting device 7 The distance l' from the end of the veneer remaining in the dryer is the length l' to the dryer outlet where the end portion of the veneer remaining in the dryer is dried to a moisture content of 20%. l').

Until the drying speed is switched, the starting end portion of the veneer that is currently being rewound subsequently is dried at the drying speed of the end portion of the veneer that was rewound earlier.

During this time, the starting end of the veneer will be overdried than usual, but thereafter the transport speed will be switched to a preset high speed to undergo the drying process and will be dried to within the permissible moisture content.

In addition, in the embodiment, the mark position by the marking device 6 is shown as the length l of the dryer from the end of the veneer that is the sapwood, but this mark position may be set in advance, and l It is better if it is longer than ``.

Thus, according to the method of the present invention, even if veneers with extremely different moisture contents are continuously conveyed in the dryer with the front and back adjacent to each other, the appropriate moisture content can be determined from the moisture content differences. By switching the veneer drying speed of the dryer at the desired position,
Any of these veneers can be dried to within the permissible moisture content, and the productivity and product quality of the veneer can be improved.

[Brief explanation of drawings]

The drawing shows an example of a series of veneer drying treatment systems for carrying out the method according to the invention. Explanation of symbols: 1: Winding ball of band-shaped veneer, 1a: End portion of previously rewound veneer, 1b: Starting end of veneer that is currently being rewound, 3: Veneer transport conveyor, 4: Dryer , 5:
Veneer unloading conveyor, 6: Stamping device that marks the surface of the veneer, 7: Detection device that detects the mark made on the surface of the veneer, l: A certain distance ahead from the rear end of the veneer that was previously rewound. 1-1': position for detecting a mark carried out by a certain length from the outlet side end of the dryer.

Claims (1)

[Claims] 1 Veneer transport and unloading conveyors capable of synchronizing the veneer transport speed with the veneer drying speed are installed at the entrance and exit sides of the dryer. A method of continuously drying these veneers by adjusting the veneer drying speed of the dryer when the starting end portion of the veneer being returned is continuously conveyed in contact with the starting end of the veneer back and forth, the method comprising: Before drying, a mark is made in advance on the veneer surface a certain distance ahead from the rear end of the veneer by an appropriate means, and after drying, the mark made on the veneer surface is located at the exit of the dryer. When the veneer is unwound beyond a certain dimension from the side edge, this mark is detected by an appropriate means, and the drying speed of the veneer in the dryer is determined from the drying speed of the veneer at the end of the veneer that was rewound earlier. The drying speed is changed to the starting edge of the veneer that is being dried.
This switching is permissible if a portion of the end portion of the veneer with the mark still remains in the dryer at the time of detection of the mark, and this remaining end portion is subsequently carried out of the dryer. A continuous drying method for strip-shaped veneer, characterized in that the drying method is set at a point when the moisture content reaches the highest value.