【正文】 m), but P kind then is not good. In abrasion aspect, K kind of toughness better, the life is longer. The hob resharpens and renovates After the hob processing certain quantity work piece, its cutting edge failure, this time must resharpen. Sharpens the after hob to have to maintain the original geometry shape。 The cutting edge must be sharp。 The cutting tool golden phase structure cannot because rub truncates the heat but to destroy. Thus when sharpens the hard alloy hob should use one kind of oil base refrigerant, it does not get up to the chlorine and the sulfur the response. Regarding scrapes the hob, sharpens after the coating not likely to use in hob such which the entity semifinished materials hardly rolls being important again. After the hard alloy hob sharpens in front of the coating, suggested carries on the pretreatment to its cutting edge. The hob rewill sharpen can except the cutting surface original coating, this will be able to reduce the cutting tool life. The cutting tool is may again spread. Usually regarding the TiN coating, may spread 3 ~ 4。 Says regarding TiCN and the TiALN coating, because coating itself has the very big internal stress, therefore on cutting edge with difficulty again again coating. After several spreading TiN coating, can have the height nonuniformity condition, and influentials the tendency which the level falls off, therefore the original coating must remove. At present has two methods to be possible to remove the cutting tool coating: Chemistry draws back spreads draws back with physics spreads. Draws back with chemistry spreads removes on the hard alloy tools the coating is one kind of fine craft, requests the operator to have the suitable level of expertise. The excessively chemistry draws back spreads not only removes the coating, moreover also will dissolve washes the cobalt cement, the damage hard alloy material microscopic structure. The cutting edge microscopic damage will produce the zigzag surface. In addition, when draws back spreads must to the hob pillow block, in the hole and the sign carries on the protection, in order to avoid damages. But physics spreads, then must carry on by the original cutting tool factory, it involves to puts in order rerubs the hob tooth profile truncates. Although draws back chemistry spreads must be much more expensive than, but obtains is a new hob, the quality and the life all can obtain the guarantee. To gearhobbing machine request In order to fully displays the hard alloy and the coating craft merit, the gearhobbing machine should do correspondingly improves. At present all advanced gearhobbing machines all press high speed roll the tooth to carry on the design, its gearhobbing machine hob rotational speed surpasses 3000r/Min, usually is 5000r/Min, the work piece main axle rotational speed and the hob rotational speed match. In addition, the engine bed has very high moves the rigidity and the hot rigidity. The advanced gearhobbing machine some main design characteristics are: Uses the pound epoxy resin lathe bed, by improves the engine bed the tendency and the static characteristic。 Has the constant temperature installment the high speed hob headstock。 High speed work piece main axle。 May use does, the wet two kinds rolls truncates the craft。 Belt electrooptical sensor digital actuation system。 The straight line rolls the guide rail system。 High speed automatic highquality goods (2 ~ 3 seconds)。 The occupying a land area of is pact。 According to manmachine engineering design。 Services conveniently. Uses scrapes the craft Regardless of is the mechanical type the CNC gearhobbing machine all can carry on scrapes, but the condition is the engine bed must equip has the work piece to the cutting tool selsyn train system. This may cause to scrape the craft economically, to has on the automatic yummy treats system the engine bed very to be also important. The electronic non contact system depends on a simulation quantity sensor to send out the pulse to survey the cutting tool main axle, the work piece main axle and the gear position. The engine bed CNC controller carries on processing to these pulses, then is opposite to the work piece main axle in the cutting tool position carries on the adjustment, causes a work piece turn of tooth and the hob knife tooth relative position relations is correct. In scrapes in the craft to have very many merits with the refrigerant: In scrapes in the process, the refrigerant has provided the lubricating ability。 Because scrapes produces is not the normal scrap, the temperature control is extremely important. Blows the scrap small is thin, does not look like normal knife filings such to be possible to carry off many quantity of heats, therefore scrapes time uses the refrigerant to be possible to control the cutting tool, the work piece and the engine bed system temperature。 The refrigerant may washes away the scrap from the cutting tool and the work piece。 Improved the work piece surface fine roughness。 Enhanced the cutting tool life. Rolls in the green truncates in the craft, correctly chooses the tooth thick remainder is very important. The remendation choice down milling rolls the tooth, because it may obtain the thickest scrap, this is helpful to the control cutting process dynamic condition, enhances the cutting tool life. The experience proved that, the cutting speed may surpass 200m/Min, enters for the quantity choice is decided by the superficially attractive fineness which must achieve. The model enters for the scope is ~ (flees knife) the method very to be also important, because scrapes time only then the rough machining section partial cutting edges only then undergo the attrition. On the contrary, in the green cutting in the process, the cutting tool precision work has partially undertaken the main process load. This meant when scraping flees the knife quantity to be supposed to be bigger, when like the gear is 12 ~ 48DP, each time flees the knife