NC Hard-cutting Of GCr15 Roll And Its Application

GCr15 hardened steel is widely used to fabricate various components of roller of high hardness and high resistance to wear which are usually finished machining by grinding process. With the development of fabrication technology, especially of cutter material and machining process, to use ceramic or PCBN cutting tool to numerical control hard-cut is a good process of both environmental benefit and economic benefit, In this text, GCr15 hardened steel welding pipe roller was selected as turning object to systematically and experimentally research on numerical control lathe using ceramic or PCBN cutting tool, requirement of GCr15 hardened steel roller on machine, cooling, lubricating and process system when numerical control hard-cut was analyzed, and processing course of GCr15 hardened steel roller when numerical control hard-cut, reasonably selection of cutter, the design of the tongs, effect of cutting parameter on roller surface quality and process program were discussed. Results showed as follows.When GCr15 hardened steel roller was hard-cut, lathe and process system should have favorable rigidity. High rigidity can make hard-cutting more stable, process quality better, and can improve cutter life. Another important sign of roller numerical control hard-cut is to ensure series machining stable. While during the course of make-and-break cutting, dry-cutting should be selected.When roller groove was numerical control hard-cut, PCBN cutting tool was mainly used to finish machining, ceramic tool was used to both rough machining and finish machining. Backing bite is an important factor to affect buffeting. When roller groove was roughly machined, ladder shape feed course is a good method of restraining buffeting, and can notably improve productivity. While roller groove was finished machined, feed course along outline reduces productivity, but doesn't produce buffeting, and improves machining surface quality. The effect of amount of feed on surface roughness is most, that of cutting rapidity takes second place, and that of backing bite is least.GCr15 hardened steel roller can be machined by automatic program, also by manual program. Automatic program is convenient, when roughly machined, ladder shape feed course is used, while finished machined, feed course along outline is used, machining time is short, but program is long and not easy to examine. When manual program is used, while roughly and finishly machined, feed course along outline is used, machining time is long, and numerical value calculation is bothering and easy to make mistakes, but surface precision after finish machining is high, and cutter impact is little. Thus according to the cutter life and machining precision, manual program is good when roller is numerical control hard-cut; while according to the efficiency and convenience, automatic program is good.