Akio KUBO’s research while affiliated with Kyushu Sangyo University and other places

In recent hobbing, the technologies of dry cutting have been developed in an attempt to improve the working environmental and prevent global environmental pollution. In this study, we investigated wear behavior (tool life), crater wear and finished surface roughness of various coated cutting tools when hardness of work material was changed by heat treatment in dry hobbing. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. The results helped clarify the following points: (1) When the hardness of workpiece material SCM415 was changed to HB131, HB144 and HB161, the tool life obtained with all of the four kinds of coated cutting tools used in this experiment in the cases of cutting HB131 (annealing) and HB161 (as rolled) work materials is longer than the case of cutting HB144 (normalizing) work material. Especially AlCrSiN-coated tool is effective. (2) For various coated tools, the crater wear tends to decrease in the order of cutting HB144, HB131 and HB161 work materials, and when cutting HB161 work material with AlCrSiN-coated tool, the crater wear is small. (3) Even if the hardness of the workpiece is changed, the finished surface roughness is as small as 1 μm when cutting with the AlCrSiN-coated tool compared to other coated tools. (4) From the viewpoints of tool life, crater wearand finished surface roughness comprehensively, AlCrSiN-coated tool is effective when the hardness of the work material is changed.

The present paper describes the influence of water-miscible cutting fluids on tool life (flank wear) and crater wear of various coated cutting tools and finished surface roughness, as compared with the cases of dry cutting and wet cutting using cutting oil in hobbing in an attempt to improve the working environment. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. The following results were obtained. (1) In the case of an uncoated tool, cutting oil was more effective than dry cutting in reducing flank wear. Cutting oil and water-miscible cutting fluids were more effective in reducing flank wear than dry cutting using TiN- and TiAlN-coated tools. The use of water-miscible cutting fluids in conjunction with TiSiN- and AlCrSiN-coated tools prolongs tool life. (2) For all coated tools, the use of cutting oil or water-miscible cutting fluids were effective in reducing crater wear. Especially, water-miscible cutting fluids were effective for TiSiN- and AlCrSiN-coated tools. (3) Regarding the finished surface roughness, in the case of dry cutting, the finished surface roughness was similar for various types of coating films. When using cutting oil or a water-miscible cutting fluid, the finished surface roughness improved compared with dry cutting, independent of the type of coating film applied. The finished surface roughness obtained using water-miscible cutting fluid was approximately the same as or smaller than that obtained using cutting oil. (4) With respect to flank wear, crater wear, and finished surface roughness, the water-miscible cutting fluid of emulsion type containing a large amount of synthetic lubricating additives was suitable for the AlCrSiN-coated tool.

This paper presents the result of a systematic dry hobbing experiment to examine the influence of cutting speed on the tool life and machining performance for a TiN-coated HSS hob. The hobbing experiments were performed under different cutting speeds from 100 m/min to 300 m/min. Some important machining items related to the tool life, for example, the influence of instantaneous cutting temperature, the characteristics of hob wear, the chip deformation and the effect of chip crush behavior are discussed in detail. The importance of the cutting speed employed in a dry hobbing process is verified, i.e. an appropriate speed not only leads to the small deformation and better fluidity of the chips and thus reduces the occurrence of chip crushing action, but also effectively control the oxidation progress of coat material. Based on the experiment results, a suitable cutting speed range due to the tested hobbing conditions is confirmed.

This paper deals with hobbing and finish-hobbing that considers the machine environment when using various hard hob materials. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. The results are summarized as follows. (1) Under the condition of hobbing with TiN-coated tools in dry cutting and with a minimal quantity of lubricant (MQL) system, P20 and P30 hob materials as the substrate show stable cutting and do not cause tool failure. The flank wear obtained with P30 is less than that obtained with P10 and P20 in the case of the coated TiAlN film tool. The MQL system shows flank wear reduction compared with dry cutting. (2) Under the condition of finish-hobbing, when using the TiN-coated tool, the flank wear obtained with dry cutting is smaller than that obtained with the MQL system. The flank wear increases in the order of P10, P20 and P30 hob materials, and the P10 hob material is effective. The TiAlN-coated P30 tool decreases flank wear and is suitable for finish-hobbing in dry cutting and with the MQL system. (3) Under the condition of hobbing, the finished surface roughness obtained with the MQL system when using TiN-and TiAlN-coated tools is smaller than that obtained by dry cutting. (4) Under the condition of finish-hobbing, the finished surface roughness obtained with TiN-and TiAlN-coated P30 is small in dry cutting and with the MQL system.

This paper deals with the influence of water-miscible cutting fluid on tool life (flank wear) compared with that with dry cutting and water-insoluble cutting oil in hobbing. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. The following results were clarified. (1) The water-miscible cutting fluid used in the test prolongs the tool life for TiN-, TiAlN-, TiSiN- and AlCrSiN-coated tools in comparison with that obtained by dry cutting and water-insoluble cutting oil. (2) It was presumed that the tool wear decreases and the tool life is improved by the lubrication effect of the synthetic lubrication additive, mineral oil and sulfuric EP additive contained in the water-miscible cutting fluid, and also by the cooling effect.

This paper presents tool life (flank wear) and crater wear of four kinds of coated high-speed steel tools and finished surface roughness in hobbing under the conditions of considering environment. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. As a consequence, the following results were obtained. (1) Under the condition of 1-thread hob, TiN- and AlCrSiN-coated tools showed the longest tool life among the four kinds of coated tools in dry and with MQL system. Under the condition of 3-thread hob, TiSiN-coated tool is effective in dry, and TiAlN- and AlCrSiN-coated tools are suitable with MQL system. (2) The crater wear of TiN-coated tool is smallest in other coated tools tested both in dry and with MQL system under the condition of 1-thread hob. TiAlN-, TiSiN- and AlCrSiN-coated tools are effective, and it was suggested that the crater wear is protected by the deposited metal under the condition of 3-thread hob. (3) The finished surface roughness, which was obtained with almost of coated tools tested at the end of cutting with MQL system both under the conditions of 1- and 3-thead hobs, is smaller than that obtained by dry. (4) From the viewpoints of tool life, crater wear and finished surface roughness, AlCrSiN-coated tool is suitable for hobbing with MQL system.

This paper deals with the influence of water-soluble cutting fluid on tool life (flank wear) of various coated cutting tools and finished surface roughness compared with dry cutting and water-insoluble cutting oil in hobbing. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. The following results were clarified. (1) In the conditions of 1-thread and 3-thread hobs, the water-soluble cutting fluid used in the tests prolongs the tool life of TiSiN- and AlCrSiN-coated tools compared with that obtained with dry cutting and the water-insoluble cutting oil. (2) The water-soluble cutting fluid used in the tests is effective for all of various coated tools in the term of finished surface roughness. (3) From the viewpoints of tool life and finished surface roughness, the water-soluble cutting fluid is suitable for TiSiN- and AlCrSiN-coated tools.

This paper presents the results of a systematic dry hobbing experiment performed on a general mechanical transmission type of hobbing machine. All four types of coated HSS hobs demonstrate satisfactory cutting performance applicable enough to practical production. Some related details such as the characteristics of hob wear, the effect of chip crush behavior and cutting speed are also discussed based on the experiment results.

This paper deals with the effect of minimal quantity lubrication (MQL) on tool life (flank wear), crater wear of various coated high-speed steel tools and finished surface roughness in hobbing. Experiments were conducted by simulation hobbing by fly tool cutting on a milling machine. The results are summarized as follows. (1) When changing the kinds of coating films, a TiAlN-coated tool showed the longest tool life. Tool lives of almost of the tested coated tools obtained with MQL system are longer than those obtained by dry cutting, and the wear reduction effect by MQL was recognized. Especially, an AlCrSiN-coated tool showed the tool life more than twice compared with dry cutting. (2) It is assumed that the crater wear is caused by the delamination of the coting film, and the crater wear in the case of MQL occurs earlier than that in dry cutting. Both in dry cutting and MQL, the crater wear does not appear on the AlCrSiN-coated tool, which is effective for the crater wear. (3) In all of tested coated tools, the finished surface roughness obtained with MQL is smaller than that obtained by dry cutting. When using TiAlN- and AlCrSiN-coated tools, the surface roughness reduction effect by MQL is large. The TiAlN-coated tool showed the smallest surface roughness of the four kinds of coated tools. (4) From the viewpoints of tool life, crater wear and finished surface roughness, TiAlN- and AlCrSiN-coated tools are suitable for MQL system.

This paper deals with the influence of various coating films of high-speed steel tool on tool life (flank wear) in hobbing with dry cutting and minimal quantity lubrication (MQL) system when changing the hob feed. Experiments were conducted by simulating hobbing by fly tool cutting on a milling machine. The results are summarized as follows. (1) In the case of hob feed of 1.5 mm/rev, TiN-coated tool is effective for dry cutting and AlCrSiN-coated tool is effective for MQL system. (2) With 4.0 mm/rev, TiSiN-coated tool is suitable for dry cutting and TiAlN and AlCrSiN-coated tools are suitable for MQL system. Especially, an AlCrSiN-coated tool showed the tool life obtained with MQL system more than twelve times compared with dry cutting.