FI58399C - FOERFARANDE FOER AUTOMATISK STYRNING AV TORKNINGEN - Google Patents

Description

• 3r * \ M (11) KUU.LUTUS, UL * A, SU ςβτ, οο IMa '' UTLÄGG N I NGSSKRI FT DOopy

Parent rr.C'Jdi? iat ^ - * - '(51) K ».ik? /int,g.3 G 01 N 5 / 04- // F 26 B 25/22 ENGLISH —FINLAND (21) Ptt * nttlh» k * mui - Pit * nttn «eknlng 773318 (22) H» k * ml * pllvt - AM & knlngtdag 07-11-77 (23) AlkuplM —Gllttghattdag 07-11-77 (41) Tullut JulklMk *! - Bltvlt offmtllg 08.05.79

PutmttU and the National Board of Registration Nihavtiuipwoe. month | u.w «, n date. -

Patent- o «h registerstyrelsen 'Antekw utitgd oeh uti. * KrifUn pubiicand 30.09.80 (32) (33) (31) Pyydttty atuolkaut — Bugird prlorltet (71) Plan-Sell Oy, Mannerheimintie 25 A 29, Helsinki, Finland-Finland (Fl) (72) Olli Heikinheimo, Helsinki, Finland-Finland (Fl) (5 * 0 Method for automatic control of drying - Förfarande för automatisk styming av torkningen

The invention relates to a method for automatically controlling drying when drying sawn timber, in which case the timber is preferably mechanically stacked on drying trolleys in a stripping machine.

When drying lumber in an artificial dryer, it is known to adjust the drying e.g. so that one or more test pieces are placed according to the drying load. By monitoring the drying of these specimens, the drying of the entire drying load can be assessed. The drying of the test pieces is examined by weighing them from time to time. When the weight of the test pieces corresponds to the desired final moisture, the drying is stopped and the the trolley is driven out of the dryer.

The drying process itself is monitored in practice, e.g. with various time relays, hydrostats and thermostats.-

However, the known drying methods have several drawbacks. The aim is to select the test pieces very carefully so that they correspond as closely as possible to the average of the entire batch of timber to be dried, both in terms of moisture and drying properties. However, in practice, this 2,58399 only materializes. This results in over-drying. Over-drying wastes electrical and thermal energy unnecessarily.

The main advantage of the method according to the invention is that it is used to determine the prevailing moisture of each batch of timber to be dried, and it is therefore not necessary to guess the moisture on the basis of laboratory tests of any test piece. This avoids over-drying, which means significant cost savings. The advantage of the method according to the invention can also be considered its easy automation.

In this case, a satisfactory result is also achieved from the point of view of occupational safety, because the removal of the drying wagons from the drying room can take place without the presence of any employee. As is well known, current occupational safety guidelines require the presence of at least two employees at each shift, as it is very dangerous to move dry wagons alone. The weight of the drying wagon containing wet timber is even more than 30 t.

In order to obtain the above-mentioned advantages, the method according to the invention is characterized by what is set forth in the characterizing part of claim 1.

In the following, the invention and other advantages obtained by it will be explained in detail with reference to the accompanying drawing. The drawing schematically shows a drying arrangement in which the method according to the invention has been applied. As shown in the drawing, the stacking of the drying wagons is performed in the stripping machine 1. The stripping machine has a drying load 2 just being loaded. The length data is entered into a computer 3 or equivalent monitoring equipment.

When the dryer load is completed, it is transferred along the rails to the dryer. Prior to drying, each load can be weighed to determine the initial moisture content of the timber by weight.

Inside the dryer there are one or more full dryer loads 7, 8, 9. Of these, the load 9 has been in the dryer for the longest time and has moved next to the outlet door 10. At this point, a balance 3 of 58399 is placed in the dryer. The balance 11 immediately informs the computer 3 of the weight of the carriage 9. The computer has calculated the volume of the timber package 9 and a certain reference weight for the weight of the package. This reference weight is the weight weighed by a completely dry timber package, the volume of which has been calculated on the basis of the information of the stripping machine.

1 As soon as the scale 11 gives a certain weight reading, the computer compares it with the weight it calculated in advance. If the weight indicated by the balance is less than or equal to the value calculated by the computer, the computer gives a control pulse to the dryer outlet door 10, which opens. The trolley 9 is then automatically removed from the dryer and the door is closed. The other carriages 7, 8 move one step forward and a new wet timber package enters from the front door 5.

The apparatus according to the invention thus adjusts the drying time for each packet separately and automatically removes the dry packet. The weighing, if any, before the dryer provides information on the weight of the timber to be dried before drying. This can be used to calculate the density of wet timber. When the scale in the dryer gives the weight of the dry timber, the amount of water removed is directly seen as the difference between the weights.

The invention has been described above with reference to only one preferred embodiment. However, the invention is not intended to be limited to the example described above, but many modifications are possible while still remaining within the scope of the inventive idea set forth in the claims. Thus, the method can be applied without weighing the timber before the dryer. The dryer itself may be of another type, for example a chamber dryer. Likewise, several scales can be placed in the dryer or other general arrangements can be made, which will be obvious to a person skilled in the art.

j