Woodworking – Rotary cutter
Patent
1992-01-30
1993-04-13
Bray, W. Donald
Woodworking
Rotary cutter
144230, 144231, 144241, 407 35, 407113, B27G 1308, B26D 100
Patent
active
052013529
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a rotatable blade for clearing units being arranged on a long, articulated parallel moving tool-carrying boom on a forestry vehicle or similar, said blade being provided with a plurality of dismountable and replacable teeth spaced around the periphery of the blade, each one of said teeth being symmetrically integrally shaped in the form of a disc with several cutting edges along its periphery.
These kind of blades are largely used when woods are cleared by means of clearing units mounted on a long, articulated, tool-carrying boom with a parallel motion mounted on a forestry vehicle or similar. The blades wear comparatively fast and, additionally are exposed to the risk of being destroyed entirely if the blade comes into contact with a stone or similar during the clearing. On the one hand this means comparatively large costs solely for the replacement of the blade, on the other hand this may also entail comparatively long periods of standstill for the machine. In connection with conventional blades the entire part of the clearing unit which holds the blade, and which is attached by means of at least eight bolts, normally must be dismounted. There also may be difficulties with the stock-keeping, and with the concomitant risks for a standstill if several blades are destroyed in an early phase. The blades are furthermore heavy and difficult to handle, especially when they are to be moved manually on location in the wood for replacement and mounting. Conventional blades may have a diameter of 70-80 cm and may weigh 75 kg or more. In this connection there are also great risks for injuries since the saw-teeth of the blade are very sharp. These risks for injuries may certainly be alleviated by means of different kinds of protective devices, but these may result in a further deterioration of the handling.
The object of the invention is to achieve a rotatable blade having a design which to a high degree alleviates the problems described above. This object is achieved in that the blade comprises a main part receiving the blade teeth in locking recesses and a pressure plate having substantially the same diameter as said main part and being arranged on top thereof an attached thereto, for instance by means of bolts, to lock the teeth in the recesses, and in that each locking recess corresponds to the periphery of each tooth and is open towards the pressure plate and the perifery of the main part so that only one of the cutting edges of the tooth projects from the blade, the remaining cutting edges being located in the recess, whereby the tooth can be removed from the recess, rotated in its own plane and replaced in the recess, so that another cutting edge projects from said blade.
In a preferred embodiment the basic form of the tooth essentially has the shape of an equilaretal triangle and is thus provided with three cutting edges.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention is described in the attached drawings wherein:
FIG. 1 illustrates a preferred embodiment of a tooth having a triangular basic shape,
FIG. 2 illustrates the tooth in FIG. 1 as seen from the side,
FIG. 3 illustrates the blade with the hub part in a horizontal plan,
FIG. 4 illustrates a section along the line IV--IV in FIG. 3,
FIG. 5 illustrates the pressure plate mounted on the upper side of the blade in order to hold the teeth in their recesses,
FIG. 6 illustrates the pressure plate sectioned along the line VI--VI in FIG. 5,
FIG. 7 illustrates the blade in a mounted condition as seen from the side,
FIG. 8 is a horizontal plan of the blade in a mounted condition with part of the pressure plate broken away in order to illustrate the arrangement of a tooth in the recess corresponding to the tooth,
FIG. 9 illustrates an alternative embodiment of a tooth with its associated recess and,
FIG. 10 illustrates another alternative embodiment of a tooth with its associated recess.
Best Mode for Carrying Out the Invention
The tooth 1 shown in FIG. 1 essentially has a triangular shape, as can be seen by
REFERENCES:
patent: 1946069 (1934-02-01), Miller
patent: 3017912 (1962-01-01), Sybertz et al.
patent: 4169690 (1979-10-01), Kendra
patent: 4271882 (1981-06-01), Valo
patent: 4462725 (1984-07-01), Satran et al.
patent: 4932813 (1990-06-01), Qvart
Bray W. Donald
FMG Timberjack AB
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