Wood-chipping machines

Details Wood-chipping machines Wood-chipping machines

1999-09-17

2001-07-10

Rosenbaum, Mark (Department: 3725)

Solid material comminution or disintegration

Apparatus

Comminuting surface provided with openings to permit...

C241S296000

Reexamination Certificate

active

06257511

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to machines for making chips from brushwood and the like. These are used by tree surgeons, contractors, and public authorities, to clear waste timber and turn it into a particulate material useful for mulching, compost production, and possibly as a material for making wood-based products such as chip-board.
The industry standard machine has a feed roller or rollers provided with teeth to grip and embed in the branches, small diameter logs, twigs and the like, and feed these through a throat to meet a flywheel generally at a radial position relative to its center. The flywheel is massive because of the requirements, and carries cutter blades on one face at a plurality of radial locations, typically three, each of which is a straight blade which has its cutting edge extending parallel to an individual radius of the flywheel and of a length corresponding to a particular dimension of the throat. One edge of the throat provides a second cutting edge. As each blade moves over the throat and across the second cutting edge, the end of the fed material, which projects beyond that edge, is impacted by the blade and chopped off Because of the nature of the material with a grain structure, a large area, as of a log, is fractured into a large number of chips. Small cross-sectional areas such as twigs may form only a single chip with each cutting stroke.
The flywheel may rotate at a high speed on the order of hundreds or thousands of RPM, and there is considerable noise from the cutters operation as well as from the driving source. The blade life is relatively short between each re-sharpening operation or replacement, due to ordinary wear and tear, and to foreign bodies which tend to be fed in, e.g., stones or grit. In ordinary operations, a chipper run more-or-less continuously during working shifts may need sharpening every 15-30 hours, and can be re-sharpened a limited number of times.
The object of the invention is to provide improvements, particularly in shortening down-time when sharpening is called for, in reducing cost of re-sharpening, and in reducing the cost of replacement blades. Supplementary objects include reducing noise and power requirements.
SUMMARY OF THE INVENTION
According to the invention, a chip-making machine has blades at a plurality of generally radial positions on a flywheel, and is characterized by each blade consisting of one or more individual cutters arranged so as to be angularly adjustable whereby different positions of the periphery of each cutter may be successively moved into operative position.
Preferably a series of circular cutters is arranged along a line containing the axis of all of the plurality, possibly, but not essentially, with all of the cutters in point-to-point contact one with the next. However, square or other polygonal cutters could be used in similar manner, preferably adjusted so that their combined operative edges do not form a straight line.
The present inventor has discovered that the industry standard machine has the effect of displacing the fed material laterally of the throat in the direction from the center of the disc to the periphery. This results in increased wear at the outer end of each of the straight-edge cutter blades used in this prior art, and perhaps increased power requirement because of less favorable mechanical advantage.
In contrast, the invention may use blades having their axes distributed along the length of an arc (i.e., the line containing the axes is not straight), which may include the flywheel center, but which has the effect of displacing the fed material inwardly towards the axis of the flywheel. This important feature of the invention is believed to result in reduced power requirements because of improved mechanical advantage. An experimental machine according to the invention is substantially less noisy than existing prior art machines, possibly due to the same feature.
A saving in blade sharpening is possible, using a plurality of cutters to correspond to each of the straight cutter blades in the prior art, because the cutter nearest the flywheel axis which performs most of the cutting, due to the feature explained above, can be re-sharpened, or if necessary, replaced without it being necessary to replace or resharpen the others. The same effect was not true in the prior art because the single blade had to be removed, and because sharpening had to be done in a jig, the whole of the length of the cutting edge had to be treated even if damage was limited to one end section.
However, it is preferred to arrange circular cutters so that each has a minor portion of its periphery exposed for cutting. Using three circular cutters in each group, i.e., to constitute the equivalent of each single straight cutter blade in the prior art (although not, or not necessarily having their axes on a straight line) effectively 120 degrees of each circular cutter may be effective. Hence, each cutter has three portions which can be used in turn, before any re-sharpening is necessary.
The cutters may each be made integral with a large diameter hub, received in a corresponding mounting socket on the flywheel, so that stresses are taken by the hub/socket engagement. Each blade may be held in position by a corresponding bolt. When blade edge replacement is necessary, the cutters may be loosened, and turned angularly to present a fresh portion of the cutting edge for use; it will be appreciated that re-sharpening is only necessary after the whole periphery has become worn. Moreover, if one cutter wears more rapidly, it may be adjusted or replaced without having to adjust or replace the unworn ones. It is believed that this feature will substantially reduce down-time, and sharpening and blade replacement costs.
Another aspect of the use of a plurality of circular cutting blades, which together form a group for moving as one over the throat of the machine, is that they combine to provide an edge which may be sinuous, instead of a straight line, and moreover which can be effectively continuous (if the discs touch each other), or discontinuous (if spaced further apart), and it is thought that these factors contribute to produce a slicing action rather than a chopping action; this has some effect on power requirement, noise, and perhaps also on blade wear.
The machine according to the present invention may be conventional in all respects except that of using the novel cutter blade arrangement.


REFERENCES:
patent: 4463907 (1984-08-01), Biersack
patent: 5961057 (1999-10-01), Turner

Affiliated with

Also associated with

Rating

Wood-chipping machines does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Wood-chipping machines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wood-chipping machines will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2515518