| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1991: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1990: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
As a tool is repeatedly used to cut wood, the cutting edge abrades in such a way that the tip of the edge becomes round. This research was carried out to develop a self-sharpening woodworking tool, such self-sharpening being realized by coating the back surface of the tool with very thin VC(vanadium carbide). This VC coating restrains abrasion on the back surface, and also maintains sharpness of the cutting edge due to the progressive abrasion mainly from the uncoated face side.
First, a low speed orthogonal cutting test, was carried out on the air-dried woods of various species. The VC-coated tool showed a fine self-sharpening characteristic like the Cr-(chromium)coated tool with all wood species used, including Melapi containing silica.
Next, a high speed peripheral up-milling test was carried out. With all kinds of substrates used in cutting Melapi, VC-coated tools showed the self-sharpening characteristic. In such cutting, the smaller the abrasion-resistant of the substrate, the shor
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ter-was the tool life. The only substrates which showed tool life long enough to be of practical use were ASP60 and HAP72 of the most powerful powder high speed steel. On the contrary, SKS3, SX105V, and SKD61 of the most fragile alloy tool steel showed a fine self-sharpening characteristic that was of practical use, in cutting of Spruce. Furthermore, the coated tools of ASP60 and HAP72 did not show the self-sharpening characteristic in cutting of Spruce. However, their abrasion resistances were considerably improved by VC. They also seemed to have sufficient practicality for use of cutting Spruce.
Next, attention was given to the thickness of a coating layer in relation to the speed of self-sharpening. The tools with VC coating on SKH51 that showed intermediate abrasion resistance in the above experiment were tested. The effective range of coating thickness for self-sharpening was found to be between 10 mum and 25 mum in cutting Melapi by the tool with SKH51 substrate. However in the cutting of Spruce using the tool with SKS3 substrate, the effective range of coating thickness for self-sharpening, was found to be between 1 mum and 6 mum. Less
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