Woodworking – Slicer – Cylindrical cutter
Reexamination Certificate
2001-07-26
2003-04-29
Bray, W. Donald (Department: 3725)
Woodworking
Slicer
Cylindrical cutter
C144S042000, C144S162100, C144S174000
Reexamination Certificate
active
06554032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for slicing fibrous feed material, in particular, trunk wood. The apparatus comprises a slicing device which rotates about an axis and is, for example, in the form of a blade ring, a blade shaft, or a blade disk, wherein the slicing device comprises slicing tools each comprising a blade carrier and a blade unit. The cutting blade edge of the blade units define a common cutting blade edge circle or a common cutting blade edge plane. The feed material is supplied in working cycles in the direction of its longitudinal axis to the blade units. Slicing is carried out in a direction parallel to the fiber orientation by producing a relative movement transverse to the fiber orientation between the feed material and the blade units. On the end face of the slicing tools, respectively, a cutting element acting transverse to the fiber orientation is arranged for producing a separating cut in a separating plane between two slicing cycles.
2. Description of the Related Art
In the utilization of wood as a basic construction material, structural parts which are comprised of glued wood chips or strands are becoming more and more import as a result of their greater and more constant strength across their length as well as their shape stability. These structural parts include, for example, OSB (oriented strand board) products. These structural parts furthermore have the advantage that high-quality products can be produced from recycled wood or trunk wood of lesser quality, wherein an almost complete utilization of the starting material is possible.
For producing the strands or flakes as the starting material for such structural parts, it is known to employ slicing devices comprising blade rings, blade shafts and blade disks comprising slicing blades. These devices have in common that the cutting edges of the slicing blades are arranged on a common cutting edge circle or a cutting edge plane which the cutting edges describe when the device is rotated. By performing a relative movement between the feed material and the slicing device, the cutting blade edges are brought into engagement with the feed material such that the cutting blade edges are parallel to the fiber orientation of the feed material.
It is conventional in connection with feed material having substantially only a longitudinal extension, such as, for example, trunk wood, to perform the slicing operation in cycles. In this connection, the trunks are combined to a bundle with parallel fiber orientation and are fed with their end facing the slicing device in the axial direction into the slicing space while being supported at the opposite end outside of the slicing space. By generating a relative movement between the trunk wood and the slicing tools, the slicing action takes place and the length of the trunk wood is shortened by the depth of the slicing space. The next portion of the wood bundle is then fed into the slicing space, and a new working cycle begins.
The quality and the properties of the final product are greatly affected by the geometry of the flakes or strands used in their manufacture. In order to ensure constant material properties, it is necessary to employ strands of uniform dimensions with boundary surfaces that are as smooth as possible. The slicing geometry is determined by the amount of radial projection of the cutting edge into the slicing space, which determines the strand thickness, as well as the spacing of the cutting edges relative to the strand breaking strip which is recessed relative to the cutting edge and which determines the width of the strand.
The determination of the length of the strand is realized by providing so-called scoring members which carry out a leading cut transverse to the fiber orientation with their radially acting cutting edges before the strand is lifted off by the subsequent slicing blade. The scoring members are arranged in the immediate area of the blade carriers and the slicing blades and are positioned circumferentially in radial planes which are staggered in the direction of the depth of the slicing space, wherein the axial spacing of two radial planes determines the length of the strand.
Problems when using such scoring members are caused by the more-than-average great loading during operation of the slicing apparatus in combination with the requirement to embody the scoring members as narrow as possible in order to maintain the flank pressure in the area of the cutting edge of the scoring member as small as possible. In order to provide a satisfactory solution in this connection, it is known to design the scoring members as thin as possible and to arrange them in precisely fitting slots within the blade carrier so that only the cutting edges project past the slot. The positive-locking securing action on both sides results in a rigid clamping action of the scoring member which protects the scoring member from being overloaded in a direction transverse to its plane. This arrangement of the scoring member however is possible only over the length of the slicing blade or the blade carrier, but is not possible on the end faces of a slicing blade because, as a result of the construction, support on both sides of the scoring member is not possible.
Experiments have shown that the known scoring members, when arranged at the end face of a slicing blade, cannot withstand the load acting thereon so that they will bend or even break off. The broken-off scoring members can enter in certain situations the slicing space and carry therefore the considerable risk of damaging the slicing apparatus.
For this reason, known slicing devices, in general, are not provided with scoring members at the end faces of the slicing blade. Instead, one relies upon the fibers at the end faces of the strand to be torn off during slicing in the separating plane between two working cycles. However, this results in frayed end faces and different lengths of the strands thus produced with disadvantageous effects on maintaining a predetermined strand geometry and thus strand quality. Further disadvantageous after effects are the unsteady running of the apparatus and increased energy consumption.
For the purpose of eliminating these disadvantages, slicing blades whose end faces are provided with an auxiliary blade have already been used. The purpose and object of such an auxiliary blade is to cut off the final strand of a slicing cycle. Even though with this measure the afore described problems could be decreased, the problems could not be solved entirely.
SUMMARY OF THE INVENTION
It is an object of the present invention to generate a clean separating cut in the separating plane between two working cycles.
In accordance with the present invention, this is achieved in that the slicing tools have a spacial receptacle or recess for the cutting element, wherein the receptacle or recess is arranged parallel to the plane of the end face of the slicing tools.
Preferably, the cutting element has a thickness of at least 4 mm, preferably 5 mm, with a flank slant angle relative to the longitudinal axis of 20°-30°.
Moreover, the blade unit is characterized in that at the end face of the blade unit a recess is arranged for the cutting element which acts perpendicularly to the slicing blade of the blade unit.
By providing a cutting element according to the invention on the end face of the blade unit, the invention overcomes the prejudice of the prior art configurations that scoring members can be arranged only across the length of the slicing blade but not permanently on its end face. Positioning of the scoring members on the end faces in accordance with the invention has the advantage that the strands to be manufactured can also be cut in the separating plane between two working cycles. This results in an improvement of the strand quality because all the boundary surfaces have a smooth surface so that strands with a uniform geometry can be produced.
The slicing action which is realized completely by means of cutting ensures moreover a more
Bray W. Donald
Kueffner Friedrich
Pallmann Maschinenfabrik GmbH & Co. KG
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