1 The present invention relates to an impregnation tank for wood preferably consisting of a cylinder-shaped pressure container with feeding and draining-off openings for an impregnation fluid. 5

Impregnation of wood usually takes place in one of the two following ways. By simple impregnation the wood is lowered into a vessel with impregnation fluid, and then the wood is raised again after a certain period of trea - o ent. The surplus impregnation fluid is allowed to drain off a short time before the wood is drying. By pressure Impregnation the wood is placed in a pressure container which is filled with impregnation fluid and then set under pressure. After finishing the pressure treatment 5 the impregnation fluid is drained off, whereafter the wood is removed and placed for drying. These two impreg¬ nation methods have the serious drawback that the surplus impregnation fluid at the end of the treatment leaves discoloured ^' stripes on the wood. At the pressure impreg- o nation the pressure container has further to be totally emptied of the impregnation fluid, before the wood can be removed. This draining off and subsequent filling before a new treatment requires much time and consequent¬ ly makes the Impregnation more expensive. As it is further- 5 more often insufficient to let the wood drain off, because part of the surplus impregnation fluid remains on the horizontal surfaces of the wood, it is necessary to wipe off the wood which again makes the impregnation more expensive on account of increased working costs and waste o of salvaging impregnation fluid. In order to avoid this drawback the tank may be arranged tiltable around a transverse or longitudinal horizontal axis. It will then be easier for the surolus fluid to drain off the wood

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as the surfaces are now sloping. Howeyer, the stripes wil still be visible. On account of the heavy weight o.f the pressure container strong and expensive tilting bearings are .required as well as a strong mechanism to tilt the container.

It is the object of the present invention to indicate an impregnation tank by which it is possible to impregnate wood without the above mentioned drawbacks. o

This object is achieved when means for holding the wood are placed in the container which means as well as the wood can be brought in rotation around the longitudinal axis of the container. By this is firstly achieved that 5 the surplus impregnation fluid will not leave disfigured stripes on the wood as the fluid during the draining-off will be distributed evenly on the surface on account of the rotation of the wood. Secondly time and energy is saved as the pressure container does not have to be o totally filled with impregnation fluid. It is sufficient if the impregnation fluid covers a smaller part of the wood because the surplus impregnation fluid from the part of the wood which have just been lowered into the vessel at the rotation will be distributed to the parts of the 5 wood which are not lowered directly Into the fluid. Thus it is not necessary to fill the tank with impregnation fluid up to the rotation axis. It has been proved in practice that the necessary fluid only makes out lo-15# of the volumen of the pressure container. o

According to claim 2 the impregnation tank may be charac¬ terized in that the means for holding the wood consist of a frame with a quadrangular cross section through which the impregnation fluid may flow, and that the means 5 may be provided with devices for fastening the wood to one or more sides of the frame. The υlacing of the wood

1 in such a frame is particularly advantageous as the fastening of the wood is thereby simplified. The impreg¬ nation takes place efficiently and evenly even if the wood is gathered in large stacks and fastened with heavy

5 force, as the individual wood pieces in spite of the fastening will move in relation to each other during the rotation and thus make it possible for the impregnation fluid to flow into the middle of the stack of wood pieces

o According to claim the impregnation tank may be charac¬ terized in that the frame is provided with wheels which can roll on the inner side of the pressure container during the rotation of the frame. This embodiment is particularly advantageous on account of the simple con- 5 struction.

According to claim the impregnation tank may further be characterized in that the frame is provided with a suitable number of openings for the impregnation fluid. o The frame is to be provided with so many openings that the impregnation fluid can flow rather freely in and out of the frame.

The invention will be described more detailed with re- 5 ference to the drawing, in which

fig. 1 shows an impregnation tank according to the invention seen in a section through the longitudinal axis of the tank and o fig. 2 shows a section along the line II-II in fig. 1.

A cylinder-shaped pressure container 1 is provided with a cover 2 and a supply pipe 3 and draining pipes and 5. 5 A frame 6 with a quadrangular cross section is embedded in two sets of plates 7, and 9,lo with a circular outer

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circumference and an inner circumference corresponding to the cross section of the frame 6. The frame 6 is supported by small wheels 11, which are embedded in the two sets of plates 7,8 and 9,lo. The wheels 11 are arran in pairs between the individual plates 7,B and 9,lo, the angle distance between each pair of wheels 11 being 90 During rotation of the frame 6 the wheels 11 roll toward the inner side of the pressure container. The frame 6 is perforated in order to let an impregnation fluid 12 flow in and out. The wood 13, which is to be impregnated, is placed in the frame 6 and is holded by means of mechanic or hydraulic pistons 14. The container is filled with impregnation fluid 12 in a way that the lower part of the frame 6 is covered with fluid.

The frame 6 is in the shown embodiment made out of per¬ forated plates, but itmay also be made out of a wire scree distended over a frame.

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