Woodworking – Feeder or presser – Feed roll
Reexamination Certificate
1999-12-03
2001-02-20
Bray, W. Donald (Department: 3725)
Woodworking
Feeder or presser
Feed roll
C144S004100, C144S246100, C144S248400, C144S335000
Reexamination Certificate
active
06189585
ABSTRACT:
The present invention relates to a single-grip harvester head for felling and processing of trees, which comprises a frame, which is adapted to be mounted on a forestry machine and which defines a tree feeding path, two feeding roller arms arranged one on each side of this path, each of which is pivotable in relation to the frame about a pivot axis defined by a pivot pin, and two feeding rollers, each of which is supported by a feeding roller arm and is rotatable about a rotation axis parallel to the pivot axis of the respective arm, the feeding rollers being movable, by the pivoting of the feeding roller arms, towards or away from the tree feeding path in order to be able to grip and feed trees with various stem diameters along this path.
Single-grip harvester heads of this type are known in many different embodiments. In addition to the above-mentioned feeding rollers and feeding roller arms, the single-grip harvester heads also comprise two sets of limbing knives arranged at a distance from each other along the tree feeding path. Each set usually comprises three knives, of which one is fixed and two are movable and which jointly surround the tree stem.
The movable limbing knives, which are hydraulically driven, press the tree stem against the fixed limbing knife, the press power exerted by the movable limbing knives having to be greater the heavier the tree stem. To control this, the diameter of the tree stem is continually measured and the hydraulic pressure is controlled by means of control and computer equipment in such a way that the press power increases as the stem diameter increases. In this connection, it is essential that the press power should not become too great since an increased press power causes an increased friction between the limbing knives and the tree stem and, thus, an increase of the charge on the feeding rollers as the tree feeding power increases. For this reason, it is essential that it should be possible to measure the diameter in a precise way. A precise measuring of the diameter is also essential because the optimisation of the marking for cross-cutting calculated by the computer equipment is based on the stem diameter. While measuring the diameter in a precise manner, the tree stem must be correctly positioned in the nip between the limbing knives. Among other things it must properly engage the breast formed by, for instance, the fixed limbing knives. However, this is not always the case since the movable limbing knives sometimes tend to “bounce” back somewhat as a consequence of the weight of the tree stem. To remedy this, the feeding roller arms in some types of harvester heads are designed in such a way that the feeding rollers when pivoting towards a tree stem are slightly adjusted angularly to partly surround the tree stem and thereby relieve the movable limbing knives of the load. In these constructions, this angular adjustment is not only made about an axis parallel to the tree feeding path but also about an additional axis, which makes the feeding rollers strive to press the tree stem out from the breast when feeding the tree in one or the other direction.
A principal object of the present invention is to provide a single-grip harvester head, in which this drawback is obviated and which in a simple way permits a well adapted angular adjustment of the feeding rollers.
According to the invention this object is achieved with a single-grip harvester head of the type mentioned by way of introduction, characterised in that:
each feeding roller arm is formed as an angular lever having two lever legs, the feeding roller being supported at the free end of one of the legs and the pivot pin of the feeding roller arm being positioned in the angular area joining the legs;
the two pivot axes are located in a common plane perpendicular to the tree feeding path;
the pivot pin of each feeding roller arm at one of its ends is articulated to the frame by means of a joint about an axis perpendicular to said plane and at its other end is controlled by a control means fixedly connected to the frame, in such a way that the pivot axis is movable in said plane but fixed in a direction perpendicular to this plane; and
the other leg of each feeding roller arm is articulated to a slide by means of a universal joint, which slide is reciprocatable in relation to the frame in the direction of the tree feeding path to maintain a constant distance between the universal joints in the pivoting of the feeding roller arms.
In a preferred embodiment, each control means has an elongated guide groove, into which the pivot pin of the respective feeding roller arm extends with its said other end, the extent of the guide groove in a direction perpendicular to said plane being substantially equal to the diameter of the pivot pin and the guide groove extending perpendicular to this direction between two end limitations, between which the distance is substantially greater than the diameter of the pivot pin.
In this connection, the feeding roller arms are preferably pivotable back and forth between an initial position, in which said other end of each of the pivot pins is located at one end limitation of the respective guide groove and in which the feeding rollers are situated close to each other, and an outwardly located position, in which said other end of each of the pivot pins is located at said other end limitation of the respective guide groove and in which the feeding rollers are situated at a great distance from each other.
The feeding roller arms are advantageously pivotable beyond said outwardly located position to an extreme position, in which said other end of each of the pivot pins is located in a position between the end limitations of the respective guide groove and in which the feeding rollers are situated at a greater distance from each other than in the case where the feeding roller arms are in said outwardly located position, the components being so designed and dimensioned that in the pivoting of the feeding roller arms beyond said outwardly located position said other end of each of the pivot pins obtains a reverse direction of motion at said other end limitation of the guide groove when moving in the respective guide groove.
In a preferred embodiment, the frame has a linear guide groove extending in the direction of the tree feeding path, and the slide has a rib inserted into this groove to control the slide during its displacement in relation to the frame.
The feeding roller arms are preferably pivotable by means of a cylinder unit, whose cylinder is articulated to one of the feeding roller arms by means of a universal joint and whose piston rod is articulated to the other feeding roller arm by means of a universal joint.
The universal joints are advantageously ball joints.
REFERENCES:
patent: 455 283 (1988-07-01), None
patent: 463 591 (1990-12-01), None
patent: 93/19909 (1993-10-01), None
Bray W. Donald
SP-Maskiner AB
Vorys Sater Seymour and Pease LLP
LandOfFree
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