To make low grade lumber into high-valued products, finger-jointing is a widely
used method in the timber industry. In certain situations, chip-out occurs degrading the
quality of the joint. To better understand the machining process, a beam-type
dynamometer based on strain gages was designed to analyze the dynamic cutting forces
parallel and vertical to the feeding direction. The test results indicate that the
dynamometer design was sensitive enough to measure small force changes at relatively
high frequencies during the cutting operation.
The test conditions were set as close as possible to that in industry. Cutting force
behavior of the rotating cutterhead was examined, and test samples with different fiber
angles were used for inspecting the influences on the chip-out occurrence and cutting
forces. The results show that cutting forces are determined by the density of the wood
and the maximum chip thickness. Slight differences in tool shape and the balance of the
cutterhead can vary the cutting force behavior. The occurrence of chip-out is dependent
on the fiber angle and the chip thickness. No relationship between chip-out and cutting
force was found, within the sensitivity of the dynamometer. Fiber angle has some effect
on the cutting force, and also influences the cutting surface quality.
A high speed video camera was also employed to visually observe the formation
of chip-out. Frame by frame analysis showed that the chip-out occured when a knife
passed through the trailing edge of the cut-block, and the failure developed in the sequel
cuts.
Cutting force and chip-out models were developed from the experiment results,
and can be used to reduce chip-out and increase recovery during finger-jointing in
ponderosa pine cut-stock operation. / Graduation date: 1993
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37237 |
| Date | 06 November 1992 |
| Creators | Liu, Yongsheng |
| Contributors | Calder, Clarence A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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