Hideharu Kato

Machining of Non-Axisymmetric Curved Surface by Lathe Turning

A new CNC lathe driven by a linear motor has been developed to realize the machining of complex non-axisymmetric curved surfaces with rotational axis such as eccentric and spiral cylindrical volume, conical cams and artificial femoral stem. These have been realized by milling and/or grinding machines. In this case, there is a serious problem. It takes a long time to machine by milling or grinding. Furthermore, the machining point between a curved surface and a milling tool or a grinding wheel can be regarded as a single point contact just as same as lathe turning. We propose a new turning method that improves the productivity remarkably by using a driven rotary tool with its unique tool layout. In this report, the machining result of the curved surface by the proposed turning method and the feasibility are also reported.Copyright

A Study on Driven-Type Rotary Cutting for Finish Turning of Carburized Hardened Steel

Recently, cutting has replaced grinding in the finish processing of hardened steel. However, tool damage is a major problem in high-efficiency operations that use high-speed cutting and high feed rate conditions instead of the present cutting conditions. Therefore, the examination of a new cutting technique that can realize high-efficiency cutting is desired. In this study, the effects and efficiency of driven rotary cutting are investigated in the finish turning of carburized hardened steel. Based on the results, flaking occurs at the cutting edge at a short cutting length of 0.2 km using single-point turning. On the other hand, even if the cutting length amounts to 1.5 km, the tool wear width without flaking is small in the case of a driven rotary tool. Additionally, the tool wear is uniformly distributed along the circumference of the cutting edge. Furthermore, based on an examination of high-efficiency processing by increasing the feed rate, it is clarified that a feed rate of 0.3 mm/rev is the optimum condition from the viewpoint of wear resistance and surface roughness. Additionally, even if the cutting length amounts to 5.0 km for this condition, the flank wear width is as small as 0.04 mm, and the tool wear progresses gradually.

Wear properties of coated ceramic tools in high speed machining of gray cast iron

The toughness of ceramic cutting tools made of silicon nitride (Si 3 N 4 ) is improving in recent years. The nose of tool, however, wears out when cutting is performed at high speed condition, and consequently the life of the tool comes to an end. In order to reduce nose wear, the effects of coating with hard materials on the resistance of the Si 3 N 4 ceramic tool to wear were investigated. Coating the Si 3 N 4 tool with TiN+TiC+Al (ON) using the chemical vapor deposition (CVD) method proved effective for reducing nose wear as compared to when it was not coated and coated with Al 2 O 3 . The nose wear of the TiN+TiC+Al (ON) -coated Si 3 N 4 tool was reduced most effectively when applied with 6-layer coating. The nose wear in the coated Si 3 N 4 tool was found to be determined by the coating in the tool land and wear end of tool. Based on the obtained knowledge described above, a novel coating method was developed in which 3-layer coating was applied to the land part of the tool, and 6-layer coating to the other part.