Research On Hob Abrasion In High Speed Dry Hobbing 16MnCr5

With the development of modern industry and environmental consciousness,conventional wet hobbing with a cutting speed of up to 80 m / min compared to Up to 150 m / min to 320 m / min for high-speed dry hobbing,higher requirements of gear production are put forward,such as high efficiency,high quality,low energy consumption,green environmental protection.A high-speed dry processing of gear come into being.Hobbing can complete the production tasks stably only in the optimal combination of equipment,tools and processing parameters.Based on the high-speed dry hobbing 16MnCr5 processing,Wear and damage of tends was studied,as well as the extension of hobs life and the reduction of production costs.First of all,the characteristics of high speed dry gear hobbing are analyzed,and some key problems in high speed dry gear hobbing are summarized.Secondly,failure forms of hobs were analyzed and the measures to improve them were put forward.The main failure forms of hobs includes wear and breakage.Wear can be divided into tooth surface wear,cutting edge passivation and pitting.Tooth surface wear is divided into rake face wear and flank wear.The form of rake face wear is crescent depression generally in the condition of high-speed and dry processing.The main reasons for crescent depression are as the swarfs at a certain temperature and pressure,friction with the tool rake surface,the friction surface first produced a bonding wear,due to high temperature,also had a proliferation of wear and tear,and bond wear and diffusion wear along with each other flowing.The flank wear of the hob usually occurs at the crest angle.Flank wear both the role of mechanical friction,and cutting force and cutting heat under the combined effect.Breakage is divided into chipping and teeth broken.Hobbing process is interrupting cutting,which is easy caused the tool to damage.At early tool breakage is the tool effect by excessive mechanical impact,made that the stress exceeds the tool's strength limit;the late tool breakage is the tool after cutting a certain period of time,the tool under the mechanical stress and thermal stress impact,resulting in the tool crack instability expansion.Then aiming at the different failure modes of the hob,the improvement measures are put forward respectively.For the rake surface wear,This can be improved by increasing the coating thickness of the hob and improving the sharpening hobbing process.As the flank wear: the wear due to the cutting edge passivation caused by non-compliance,improved by improved sharpening process and edge passivation before coating;the wear due to too thick coating thickness,improve by improving the coating process;the wear due to pitting problems,through the retreat coating process to improve.As chipping,by choosing a reasonable amount of cutting,use a reasonable processing route.As well as improve the rigidity of the processing system to be improved.Finally,conducted a technical and economic analysis.Include two research directions,on the one hand to maintain the current theoretical lifetime expectancy,shorten the processing of the workpiece beats,increase work efficiency;on the other hand,maintain the current processing beats,increase hob lifetime per time,reduce time of change tool,saving tools cost.Practice has proved that improving the hob material is more effective than changing the processing parameters.