Patent Application
20080023105
To increase productivity in a sawmill wood must be cut faster and with less gap between pieces. Speed has reached a limiting threshold as we are close to the maximum cutting abilities of saws and chip heads. Therefore the only remaining avenue left to increase throughput is to reduce gaps between pieces. Gaps are required to reset the cutting tools between pieces to some preferred positions as dictated by an optimizer. The ability to move the cutting tools quickly is dependent on the force available, the mass to be moved and the friction of the sliding members. Of these the most significant is the mass.
Canter or chipping heads are driven by an electric motor through a drive system of sheaves and belts to a rotating arbor, on the other end of which is the chipping head. This whole assembly is mounted on a structural base resting on slideways and moved by a linear positioner. This unit typically may weigh eight thousand to ten thousand pounds.
In order to reduce this mass and achieve faster set times, this invention has altered this configuration. The motor, drive and supporting base are now fixed and only the chip head, its supporting arbor and bearings and a frame containing slideway bushings move. Drive to the chip head is by a truck type drive line with a slip joint. The set distance of the chip head is accommodated by the slip joint travel. The weight of this part has now been reduced to two thousand pounds which allows for faster set times.
In one embodiment employing two one hundred fifty horsepower, 1800 RPM TEFC™ motors driving a corresponding pair of chipping heads in a canter head section, the motors and drive to jack shafts are fixedly mounted, that is, they do not move with the movement of the chipping heads. The sets, that is, the movements of the chipping heads are accomplished by a slip joint in each drive line.
It has been found that, for example; approximately one and one half inches of translation of each chipping head may be accommodated by the corresponding slip joint in the drive line, which thus allows the corresponding motors to be mounted stationary. The processed piece rate is thereby improved. However, it is not intended that the present invention be limited to only 1½ inches of slip in the slip joint, or that the slip joint necessarily be of the kind found in the prior art as used for example in the rear drive of trucks to allow for movement of the suspension. The present invention is broader than that and is intended to encompass other forms of drive lines and joints which allow for relative translation of the chipping heads relative to their motors, and that the translation of each chipping may exceed one and one half inches of travel while allowing the motors to remain stationary.
Thus as seen in the plan view of
In alternative embodiments reducing heads such as chipping heads 14 may be replaced with saws 26 (also shown by way of example in dotted outline) to provide for active edging for example, in which case carriage 22 may also advantageously be articulated or otherwise translated not only transversely but also angularly about exemplary axis of rotation C.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
This application claims priority from U.S. Provisional Patent Application No. 60/833,275 filed Jul. 26, 2006 entitled Canter Chipping Heads Having Drive Line Slip Joints.
| Number | Date | Country | |
|---|---|---|---|
| 60833275 | Jul 2006 | US |
