Woodworking – Special-work machine – Tree felling
Reexamination Certificate
1999-11-19
2001-02-06
Bray, W. Donald (Department: 3725)
Woodworking
Special-work machine
Tree felling
C030S123400, C083S072000, C083S169000
Reexamination Certificate
active
06182722
ABSTRACT:
The present invention relates to a saw assembly for a grip-harvester, comprising a stand; a bar; a saw chain running around the bar and a chain sprocket; a bar holder pivotably journalled on the stand; a saw motor driving the chain sprocket; and a feeding-out and feeding-in device for feeding the bar out and in to perform a sawing operation, said feeding-out and feeding-in device comprising a hydraulic cylinder mounted on the stand and having a piston rod, and connection means to transmit the movements of the piston rod to the pivotable bar holder; a saw box in which the bar is mounted for feeding out of said box; and a liquid supply device for supplying at least one functional marking liquid to a cut surface produced during a sawing operation, which liquid supply device comprises at least one nozzle mounted with a holder and so directed that a liquid jet encounters an opposing side surface of the bar at an acute angle a and is deflected in towards the cut surface via a space between the bar and the cut surface.
Grip-harvesters are used to a great extent for mechanised felling of trees, and are equipped with hydraulically operated chain saws, generally designated saw assemblies. To achieve satisfactory operating results when using such saw assemblies it is particularly important that functions for chain tightening and lubrication of the saw chain are well developed and that certain other additional functions, such as tree marking and bar control, are also included in or in the vicinity of the saw assembly.
A grip-harvester is an implement with which a tree can be felled, the limbs removed and the felled tree cut into smaller pieces, the lengths of which are dependent on the purpose to which the sawn log shall be put. The grip-harvester comprises several main components, such as a rotator, a link system, a gripping unit with knives for cutting off limbs, a trunk-feeding device, a stand, a saw box and a saw assembly. The grip-harvester is preferably freely suspended via its rotator and link system from the tip of a forest crane which is in turn mounted on a vehicle designed for being driven in forest land and other rough terrain. The vehicle with crane and grip-harvester is used both for felling trees and at the same time removing the limbs and cutting the tree into shorter pieces. A method of operating known grip-harvesters with known equipment can be described as follows. The operator places the grip-harvester against the standing tree and manipulates the gripping claws to encompass the tree. The operator then activates the saw assembly so that the bar with saw chain swings out and cuts the tree at its lowermost part. During this phase and when the tree falls to the ground a urea liquid or the equivalent shall be applied to the upper surface of the remaining stump as efficiently as possible, without the cut surface of the cut tree being touched by the liquid.
When the tree has been felled, the operator applies the grip-harvester on the root end of the felled tree and initiates the feed function, whereupon the tree is fed towards the de-limbing knives so that the limbs around the trunk are cut off and removed from the trunk. While the tree is being fed along the operator also initiates feeding out the bar so that, when a suitable length of the trunk has been fed along, the bar will swing out and cut off the length of de-limbed trunk that has been fed along. The operator determines what is a suitable length depending on the desired use to which the log shall be put, e.g. if it is to be used as timber (sawn timber), pulp wood or for some other purpose. To enable the operator of a following machine, called a forwarder, to correctly sort the wood into timber, pulp and other types of cut pieces of wood when loading it, the operator of the grip-harvester must mark the surface of the logs with a colour stripe as they are cut from the original tree, different colours being used for the various types of logs cut, one colour for timber, another for pulp, etc.
The colour-marking liquid is applied to the cut surface of the cut log via a tank system on the grip-harvester or its carrier. One of the most usual methods of supplying the liquid is to spray it towards the cut surface of the cut log through a nozzle on the grip-harvester's stand. It is extremely important that the nozzle is aimed at the log in such a way that the liquid is sprayed on the middle of the cut surface and that the jet can be concentrated to produce a colour stripe across the surface. However, this entails considerable difficulty and the method is therefore not considered to be sufficiently efficient. Another known method of supplying the liquid is to spray it out through specially arranged channels in the bar, separate channels being arranged for each colour required. This method is more efficient since the liquid can be sprayed onto the surface of the cut log in the right place and also automatically forms a colour stripe since the supply of colour can start when the bar is applied against the tree to be felled and can be discontinued when the bar has sawn off the log. However, the method entails a great increase in cost for the bar in comparison with a standard bar, as a result of the arrangement of the channels inside the bar. This method is therefore not appreciated by the users.
In all the methods of supplying liquid described above, start and stop signals for the supply of liquid are obtained with the aid of electronic signals from the electronic sensor system.
In mechanised felling and processing of trees in which grip-harvesters of the type described above are preferably used, it is necessary to be able to spray out various types of functional liquids on to the cut surface of the de-limbed and cut tree trunk at the time of sawing, in an automatic but reliable manner. When the tree has been felled it must be graded and processed. This marking, i.e. dividing into lengths, is performed with the aid of a marking computer in the harvester. Each log shall be marked by marking liquid being sprayed onto the cut surface of each individual log. Separate colours are used for the different grades or assortments to be separated. The equipment consists of a tank for the various coloured liquids, a pump and a spreader. The spreader on a harvester consists either of a special bar with pre-drilled channels for each colour and corresponding holes, or of a nozzle. In both cases the composition is sprayed over the end of the tree during the separation phase. The drawback of the special bar is that it is more expensive than standard bars, while the use of nozzles means that it may be difficult to obtain efficient marking since it may be difficult to set the correct spraying angle.
There is therefore a great need for some form of arrangement that enables efficient colour marking of logs, while still using standard bars.
The object of the present invention is to provide a device in a saw assembly of the type described in the introduction, which enables efficient supply of marking liquids for logs, using standard bars and eliminating current drawbacks with the use of nozzles.
The saw assembly according to the invention is characterized in that the nozzle with its holder is mounted inside the saw box, so that it is held at a fixed predetermined distance from the tree, measured at the start of the saw cut to be executed, when gripping claws are arranged to encompass the tree and press this against a free edge of a top plate of the saw box, and in that the saw assembly comprises a control means arranged to initiate supply of a liquid jet when the bar has been inserted a predetermined distance into the tree.
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patent: 3720247 (1973-03-01), Lindblom
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patent: 4250935 (1981-02-01), Helgesson et al.
patent: 5097881 (1992-03-01), Mack
patent: 5143131 (1992-09-01), Seigneur et al.
patent: 5564484 (1996-10-01), Ketonen
patent: 5845402 (1998-12-01), Leini
patent: WO 93/23218 (1993-11-01), None
patent: WO 95/27599 (1995-10-01), None
Bray W. Donald
Hultdin System AB
Nixon & Vanderhye P.C.
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