Curved Milling Paths for Higher Side Board Yield in Sawn Timber
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Solution Overview
Problem
Existing methods for producing sawn timber from tree trunks do not fully optimize the yield of side boards, particularly when dealing with the natural curvature of the trunk, leading to inefficiencies in the use of the available wood material.
Innovation Solution
The method involves adjusting milling tools to follow the curvature of the tree trunk during the milling-out of corner regions, allowing for side product boards with a crooked shape that can be straightened later, and specifying a tolerance range for the crook to enhance yield, while using a device with controllers to guide the milling and sawing processes accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If milling tools are moved in a straight line during corner region removal, then the processing is simple and fast, but the yield of side product boards is reduced due to not accommodating trunk curvature
Solution Approach 1:
The milling tools are adjusted to follow a predefined arc during the feed movement of the tree trunk, transforming the static straight-line movement into a dynamic curved path that adapts to the natural curvature of the trunk. This dynamic adjustment allows the milling tools to accommodate the trunk's curvature while maintaining efficient processing.
Solution Approach 2:
The milling tools are moved along a predefined arc rather than a straight line, introducing curvature to the tool path. This curved movement pattern matches the natural curvature of the tree trunk, enabling better utilization of the corner regions and increasing the yield of side product boards.
2Quantity of substance
If side product boards are cut with strict straightness requirements, then the quality is high, but the yield is reduced due to discarding crooked boards
Solution Approach 1:
The tolerance range for the crook of side product boards is specified and relaxed, changing the precision parameter from strict straightness to an acceptable range. This allows crooked boards to be utilized as rough sawn side product, significantly increasing the yield while maintaining adequate quality for the intended application.
Solution Approach 2:
Different quality requirements are applied to different parts of the side product boards. The crook tolerance is specified for the overall board, allowing local deviations from straightness while maintaining adequate quality for rough sawn applications. This differentiated quality approach maximizes material utilization.
3Quantity of substance
If the milling tools are adjusted to follow the trunk curvature, then the yield of side product boards increases, but the processing time and complexity increase
Solution Approach 1:
The arc along which the milling tools are moved is predefined on the basis of a measurement of the tree trunk before the milling operation. This preliminary measurement and arc definition allows the milling process to follow the trunk's curvature without real-time complex adjustments, reducing processing time while maintaining high material utilization.
Solution Approach 2:
The arc for milling tool movement is determined based on measurement data of the tree trunk's curvature. This feedback from measurement to process planning ensures that the milling operation is optimized for the specific trunk being processed, maximizing yield without requiring excessive processing time.
Data Source
AI summary
In order to increase the obtainable sawn timber volume in the side board region during the production of sawn timber from a tree trunk, in a method in which the tree trunk is canted at at least two sides, preferably four sides, a remaining wane region is milled out at at least two mutually opposite corner regions by milling tools, and a side product board is cut off by a saw cut along a plane bounded by the corner regions, it is provided that, to mill out the corner regions, the milling tools are moved relative to the tree trunk in an arc, predefined on the basis of a measurement of the tree trunk, by virtue of the fact that, during a feed movement of the tree trunk relative to the milling tools, said milling tools are adjusted so as to follow the arc.