Abstract: A method for cross-cutting trees, where a trunk to be cross-cut is advanced relative to a lopping means for cutting off branches on the trunk. A signal representing the lopping force required is generated and is combined with a signal representing advanced length of the trunk, so that a knot signal representing the presence of knots on the stem is obtained. Said knot signal is used for automatic control of the cutting of the trunk as a function of the presence of knots on the trunk. There is also provided an equipment for performing the method.

Abstract: A method and apparatus is provided for measuring the ratio between web tension and web substance by causing the web to vibrate at its resonance frequency, measuring the pressure variations or the signal causing the web vibration to produce a first signal, measuring a signal in phase and representative of the vibration of the web and to produce a second signal, comparing the phase difference of the first and second signals so that a deviation from a predetermined phase difference produces an output signal, and controlling the frequency of the signal or pressure variations causing the web to vibrate in response to the output signal so that the predetermined phase difference is maintained.

Abstract: A synthetic resin product which may be used for gluing wood products and the like comprises a lignin and a low molecular weight liquid which is capable of penetrating, swelling and reacting with the lignin to form a hardened product. The low molecular weight liquid may be a solution consisting essentially of formaldehyde and phenol and may also contain an acid or alkaline hardener. Examples of acid hardeners include ammonium chloride, paratoluene sulphonic acid and the like, whereas examples of an alkaline hardener include sodium carbonate, sodium hydroxide, ammonium hydroxide and the like. The formed resin product is very suitable as an adhesive and utilizes lignin not ordinarily suitable as an adhesive and generally regarded as a waste material.

Abstract: Hard and medium density board made of lignocellulosic fibers having a central layer with substantially higher concentration of set resin than both the outer layers of said board have as good strength properties as a corresponding board having said higher concentration of said resin throughout the thickness of the board. Said board is produced by introducing a thermosetting resin solution or a high resin content pulp into and evenly across the width of the central layer of the pulp or the wet lap to be pressed and heat treated, the pressing period being shortened as well as the press cycle. Said process can be carried out with an apparatus including a member to be inserted in the pulp slurry flow in the headbox of a board machine or in the flow on the moving continuous wire screen of the board machine comprising an element having nozzles or slits through which a thermosetting resin solution or a high resin content slurry can be brought to flow.

Abstract: A tension in a paper or foil web is measured by subjecting an area of the web between points of support to transverse oscillations. The impedance of an oscillation generating means located adjacent the web changes with the oscillation and impedance is measured with the transverse oscillation at a frequency approaching the expected fundamental resonant frequency for the web tension under consideration. The damping effect of the transverse oscillations by the web is a function of the web tension.

Abstract: The percentage of suspended substances in a flowing medium is indicated by illuminating said medium with light perpendicularly to the direction of flow. The light intensity is held mainly constant at a predetermined value. Detection is made by a first light detector of light radiated from the medium in a predetermined direction and the electrical signal obtained is led to a device squaring the effective value of the portion of said signal lying within a predetermined frequency range. The percentage of the suspended substance is obtained from said square of the effective value.

Abstract: This invention relates to improvements in measuring the concentration of suspended substances in a liquid, the substances consisting of components of different geometrical size. The liquid is flowing in a pipe and is illuminated transverse to its flow direction by one or more light sources. A detecting means is arranged to detect light spread by the suspended substances in the liquid in another direction than that of the illuminating incident radiation. This detecting means delivers two electrical signals, the first of which represents a D.C. level measured during a predetermined time and corresponding to a detected level of luminous intensity. The second signal represents the number of times during the same said predetermined time that the detected level of luminous intensity has exceeded a definite discriminator level.

Abstract: A device for determining by means of light the average thickness of a layer, permeable to said light, arranged on a surface having properties different from those of the layer with respect to the light used, and also adapted to be used to provide a measure of the topography of a surface substantially opaque to the light used, includes an opaque shield that bears substantially perpendicularly with one edge against the layer when thickness is being determined or against the surface when surface topography is being measured. At least one light indicator shielded from direct incident light is arranged on the side of the shield opposite to the side on which the light source is located.

Abstract: A method of producing cellulose pulp from a starting material containing lignin and cellulose, particularly from wood, wherein the starting material is treated with an organism capable of forming lignin-decomposing enzymes under conditions such that the lignin is substantially decomposed without appreciably affecting the cellulose.

Abstract: A package or container made of paper or like material having a number of planar panels which are reinforced solely in narrow zones extending along the panel edges by a thermoset resin impregnating the material. A package forming method of locally impregnating a package blank in load carrying areas with a thermosetting resin.

Abstract: Increased pulp yields are obtained by alkaline digestion of cellulosic material until a pulp yield of not above 65% is obtained, lowering the pH of the digestion liquid is lowered to allow 11 causing organic substances to precipitate from the digestion liquor and then continuing digestion in the presence of the pulp until at least 5% of the organic substances which have been precipitated out are absorbed by the pulp.