Woodworking – Process – Including monitoring of operation
Patent
1993-12-08
1995-06-06
Bray, W. Donald
Woodworking
Process
Including monitoring of operation
144 3R, 144 39, 144370, 144378, 144367, B27B 100, B27M 108
Patent
active
054213860
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for dividing logs, particularly curved logs.
The basic problem when sawing logs is that the logs are round and, in a first approximation, are conical, while boards are desired in rectilinear shape. The residual wood when sawing can be used in the pulp industry provided it can be divided into wood chips with long fibres. This has for many years been done with a so-called chipper, thus providing a log with large flat portions, and from the four sides there are then sawn side boards with wanes, which are sawed off in a following edge saw as laths. The remaining block is then sawed in an obvious manner in the desired dimensions.
In order to obviate the need to edge waned side boards, it has been suggested that from the log itself there be removed the wood corresponding to the wane laths, by means of two cuts for each lath, forming an inner corner, this being accomplished by milling/chipping, thus providing usable chips. The side boards can then be cut out later without any wane. One of the said cuts thus forms the board edge surface and it must be somewhat smooth, and this puts particular demands on the milling tool, see e.g. DE-A-3 114 843 or SE-A-7906747-6. Other tools are also conceivable for achieving the intended good surface, of a quality corresponding to a sawn surface.
Another problem in sawing is that the logs are seldom straight. In Scandinavia this problem has long been dealt with by sawing along a curved path with the saw cuts essentially parallel to the pith. The resulting boards and planks will be crooked to be sure but they can be dried while held straight in a pile and thereafter remain straight without inner stresses. Straight sawn lumber from a curved log will, despite being laid in piles, tend to be crooked and warped after drying. Such curved sawing is usually done by first orienting the curvature essentially in a vertical plane and planing and sawing off the side boards with vertical plane cuts. The log is then turned 90.degree. and the rest of the sawing is then done along a curved path by arranging steering means slightly in front of the saw itself, and the log is then passed through following its curved shape.
It is a general purpose of the invention to increase the economic yield when sawing logs, both in the form of boards of highest possible quality and good chips by optimizing the sawing both in regard to the truncated conical ideal shape of the log and to the curvature which is almost always present.
This is achieved according to the invention by virtue of a method of the type described by way of introduction which has the characterizing features disclosed in the characterizing clause of claim 1. A suitable device for carrying out the invention is disclosed in claim 6.
The solution suggested according to the invention can in short and schematically, without limitation, be described as follows: The log is placed with its curvature in a vertical plane and is planed in this position from the sides so that two parallel planes are obtained. It is imparted a polygon shape by cutting out "inner corners". First thereafter, the log is turned 90.degree. and the prepared boards are sawed out. The cutting out of the "inner corners" is done while following the curvature of the log, i.e. with a vertically displaceable chipping means, while the subsequent sawing is effected by the curved sawing method which is known per se.
The invention will be described on the basis of an example and with the aid of the figures.
FIG. 1A shows a log prepared for curvature sawing.
FIG. 1B shows a portion thereof indicating the placement of the cuts for taking out side boards.
FIG. 1C shows an alternative configuration of cuts.
FIG. 2 shows schematically a complete saw-mill line, where the logs enter from the left and are completely sawn.
FIG. 3 shows the latter portion of the line in FIG. 2 on a larger scale.
FIG. 4 shows a view from the front of a corner-milling tool.
FIG. 5 shows the same corner-milling tool from the side.
FIG. 6 shows the same corner-milling tool from
REFERENCES:
patent: 3934630 (1976-01-01), Cockle
patent: 4335767 (1982-06-01), Reuter
patent: 4548247 (1985-10-01), Eklund
patent: 4572256 (1986-02-01), Rautio
patent: 4711279 (1987-12-01), Reuter
patent: 4848427 (1989-07-01), Reuter
patent: 4881584 (1989-11-01), Wislocker et al.
patent: 5143127 (1992-09-01), Rautio
patent: 5320153 (1994-06-01), Knerr
Ari AB
Bray W. Donald
LandOfFree
Breakdown of logs does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Breakdown of logs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Breakdown of logs will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-980672