Technical area

This invention concerns a method for monitoring of timber that is being dried in a drying arrangement where the method comprises detection of a change in dimension. The invention concerns also an arrangement for the monitoring of the drying process of timber in a drying arrangement where detection of a change in dimension takes place, and a drying arrangement comprising such an arrangement.

Background to the invention

When timber is dried in a drying arrangement, it is desired to monitor and control the drying process as much as possible, such that the dried timber obtains the properties that are desired, and such that the drying arrangement can be used in an efficient method and one that uses time optimally.

The drying of timber means that the water that is present in the timber is caused to leave the timber. It is desired to measure and control this expulsion of water, the drying process, in order to be able to adjust the drying arrangement and the drying process. It is a well-known phenomenon that something that is dried shrinks, as can be seen by considering how an apple becomes crinkled and shrunken as it dries.

The fixing of various pieces of measurement equipment to timber inside a drying chamber is previously known, as is the mechanical measurement of the shrinkage of at least one plank in the stack of timber that has been placed in the drying arrangement. Several measurements at several measurement points should be carried out in order to ensure the reliability of the measurement, something that requires many measurement arrangements. The fixing of many measurement arrangements is a time-consuming process. As the timber dries, and as shrinkage and other changes of shape take place, each measurement arrangement may be disturbed in its placement, and this reduces the reliability of the measured values obtained.

Description of the invention One purpose of this invention is to make it possible to detect a change in dimension of timber that is being dried in a drying arrangement in a cheap, safe and reliable manner.

This purpose is achieved with a method for monitoring of timber that is being dried in a drying arrangement where the method comprises detection of a change in dimension having the technical characteristics that are specified in claim 1 , with an arrangement for the monitoring of the drying process of timber in a drying arrangement where detection of a change in dimension takes place having the technical characteristics that are specified in claim 7, and with a drying arrangement according to claim 14.

Description of drawings

Figure 1 shows an embodiment of an arrangement according to the invention.

Figure 2 shows drawings of the timber at time T1 and at time T2, after a certain drying time.

Figure 3 shows a schematic drying arrangement according to the invention.

Description of embodiments of the invention

A method according to this invention for the monitoring of timber 1 that is being dried in a drying arrangement comprises the detection of a change in dimension. This invention is based upon the idea that monitoring of the timber 1 is to take place without contact, that no part of a measurement arrangement, a monitoring arrangement, requires being fixed on to the timber.

The method comprises a method in which the detection takes place through reproduction of the extent X of the timber in at least one direction represented by at least one of length, breadth and height, during the drying process at, at least, two different points in time T1 and T2, in order to obtain at least a first B1 and a second B2 reproduction that demonstrate the extents X1 and X2 of the timber in at least one direction at the two points in time. The method comprises the measurement of the extent X1 of the timber on the first reproduction and the measurement of the extent X2 of the timber on the second reproduction. See Figures 1 and 2.

A comparison of the two extents X1 and X2 at the two different points in time T1 and T2 is then carried out. The difference X1-X2 between the extent X1 of the timber on the first reproduction B1 and the extent X2 of the timber on the second reproduction B2 is then determined. This normally tales place through measurement and calculation, but it may also take place visually or using another comparative method that can detect a difference. Determination of a change in dimension is thus carried out. The method comprises also relating the change in dimension to the loss of moisture from the timber, the drying process of the timber, when the change in dimension demonstrates a reduced extent, shrinkage, of the timber.

Each reproduction takes place through photography of the timber 1 in order to obtain a photograph, a digital image, or another type of image. The term "photography" is here used to denote all possible forms of reproduction of the timber that produce a result that can be manipulated and that makes possible the further evaluation of changes in dimension of the timber. The reproduction, and thus the monitoring of the timber and the detection of changes in dimension, takes place through the photography without contact. It is not necessary to mount any arrangement onto the timber and the reproduction, the photography, can be automatically controlled, which means that it is not necessary for an operator to be present during the monitoring of the timber.

Since the timber 1 is usually stacked and the stack of timber may be large and difficult to reproduce in its entirety, the method comprises the selection or determination of a limited region A of the timber for the repeated reproduction and measurement processes required.

At least one of the height, length and breadth of the timber can be replaced by at least one of the height, length and breadth of a region of the stack of timber, or at least one of the height, length and breadth of an individual plank. At least one of the extents in height, length and breadth should demonstrate a change in dimension in this region during the drying process for the timber.

The selection and determination of a region A may be made clear by illumination of the region desired. The illumination makes the region clear purely visually and makes it easy to detect the region, and it makes it easy to record a change in extent between two different reproductions of the same region if the region that surrounds the illuminated timber is reproduced with a different, darker, colour on each reproduction. This usually arises naturally due to the formation of shadows in a stack of timber.

It thus becomes possible to record the shrinkage that takes place in the direction X of extent, at least one of the height, length and breadth of the timber, which is illuminated and demonstrates two edge sections a and b of the timber, the region of timber, or a plank that can be used to define limitations of extent. The extent X, the direction of extent, will be reduced as the timber 1 dries and shrinks.

The illumination of a region A takes place, which region has fixed limits in either the vertical direction or the horizontal direction. Figures 1 and 2 [sic, but I wonder if this is really the two parts of Figure 2] show two reproductions of timber before and after the drying process, or before drying at time T1 and after a certain time of drying at time T2. The extent X that is studied in the example shown lies in the vertical direction. The region A can be selected as a narrow region; the illuminated region can be interpreted more as a line.

The illumination can take place of a complete stack of timber and it is possible to measure height, length or breadth of the complete stack of timber on two reproductions and to compare the changes, the modifications, that have taken place in these measurements. It should in this case be remembered that also the stacking laths that are used in the stacking of the timber contain moisture and undergo a drying process that involves a change in dimension. This change must be one parameter that is included in the calculation model that is used.

The illumination and the measurement may also be carried out on one or several individual planks. No compensation or adjustment for the stacking laths needs to be made in this case.

The change in dimension, the difference between the first extent X1 and the second extent X2, that is the result can be related to the time between the first and the second reproductions, in order to obtain a measure of the rate of drying.

The change in dimension can be related also to at least one of the temperature and the humidity in the drying arrangement at the two different times of reproduction. This information can be used to change at least one of the temperature and the humidity in the drying arrangement, and it is possible also to couple it to the rate of drying. This can result in either raising or lowering of the temperature, depending on the drying result that is desired.

An arrangement 2 according to the invention, see Figure 1 , for the monitoring of the drying of timber 1 in a drying arrangement in which detection of a change in dimension can be carried out, comprises an arrangement 3 that reproduces the extents X1 and X2 of the timber during the drying process at at least two different points in time T1 and T2 in order to obtain at least a first B1 and a second B2 reproduction that demonstrate the extents X1 and X2 of the timber in at least one direction. The arrangement 3 for the reproduction of the timber 1 concerns all types of arrangement that make possible the reproduction of the timber and that give a result that can be manipulated that makes possible the further evaluation of changes in dimension of the timber, something that also influences the selection of a suitable arrangement for the reproduction. The reproduction of the timber 1 results in a photograph, a digital image or another type of image or information that can be manipulated.

The reproduction arrangement 3 makes possible photography of the timber 1 and it is appropriate that it be of a digital nature. It is not necessary that the photography result in a physical image, nor is it necessary that a physical image be presented: the result can be limited to the information that is of interest for the determination of extent and for the determination of the change in dimension. The information that is present in the reproduction arrangement 3 may be manipulated solely digitally. The reproduction arrangement 3 may be a camera or another unit that reproduces information. The reproduction arrangement 3 is located in a suitable manner inside the drying arrangement; one suggestion is that it be located at a wall inside the drying arrangement, in its drying chamber. It may be located also on some form of support bracket or displaceable arrangement, depending on the type of drying arrangement, the number of stacks of timber, the direction from which the timber is to be monitored, etc. The number of reproduction arrangements 3 is not limited, and at least one reproduction, photography, arrangement may be arranged such that it possible also to displace it inside the drying arrangement.

The arrangement 2, the monitoring arrangement, according to the invention comprises an arrangement 4 that measures the extent X1 of the timber on the first reproduction B1, an arrangement 5 that measures the extent X2 of the timber on the second reproduction B2 and an arrangement 6 that determines the difference between the extent X1 of the timber on the first reproduction B1 and the extent X2 of the timber on the second reproduction B2, and determines in this way a change of dimension X1-X2. This normally tales place with the aid of an integrated arrangement that measures, calculates and compares, but it may also take place visually or using another comparative arrangement that can detect a difference.

The arrangement 2 according to the invention comprises further an arrangement 7 that relates the change in dimension X1-X2 to the loss of moisture from the timber 1, the drying process of the timber, when the change in dimension demonstrates a reduced extent, shrinkage, of the timber. The arrangement 2 comprises an arrangement 8 that makes clear the selected and determined limited region A of the timber for the desired repeated reproduction. This arrangement 8 for clarification comprises a light source 8.1 with which to illuminate the region. The light source 8.1 is a light source that can be limited and directed, such as a laser, for constant retention, determination, of the extent of the region in at least one direction.

The arrangement 8 for clarification, limitation, comprising the light source 8.1 is located in a suitable manner inside the drying arrangement, one suggestion is that it be located at a wall inside the drying arrangement, in its drying chamber. It may be located also on some form of support bracket or displaceable arrangement, depending on the type of drying arrangement, the number of stacks of timber, the direction from which the timber is to be monitored, etc. The number of light sources is not limited, and at least one light source can be arranged such that it can also be displaced inside the drying arrangement.

The arrangement comprises an arrangement 9 that makes possible a comparison of the change in dimension relative to the time elapsed between the first B1 and the second B2 reproductions.

The arrangement 2 further comprises an arrangement 10 that makes possible a comparison of the change in dimension relative to the time elapsed between the first B1 and the second B2 reproductions and an arrangement that makes possible comparison of the change in dimension relative to at least one of temperature and humidity.

The arrangements 4-7, 9 and 10 that are mentioned in this description may constitute free- standing arrangements or they may be components of the same unit C. The unit C may be located inside or outside of the drying arrangement. They may be integrated with each other in different ways, for example in control and monitoring units of various types that are often, in various conceivable manners, connected to a computer, different possibilities of display, or in another manner parts of a computer environment.

Figure 3 shows a drying arrangement 11 according to the invention and this may be both a batch dryer and a continuous dryer, and it comprises an arrangement of the type that has been described above. A drying arrangement according to the invention comprises also other component parts and arrangements that are required for the drying process.

The term "air" may correspond to another freely chosen drying agent suitable for use in a timber dryer. The reproduction of the region without contact makes it possible to place a stack of timber in a drying arrangement and subsequently to detect and record a change in dimension of the timber, shrinkage, without the precision or reliability of the measurement being placed at risk and without requiring time for the mounting of measurement equipment, since this is already arranged inside the drying arrangement.