Researches On The Mechanism In The Grinding Of The Grinding Wheel With An Abrasive Phyllotactic Pattern

The method of grinding has special characteristics and irreplaceable advantages.The grinding roughness of workpiece is lower than the workpiece processed by turning and milling.Its processing efficiency is higher and its cost is lower than non-traditional machining methods such as laser processing and electrolytic machining.Therefore,grinding is one of the most common precision machining technologies.However,grinding has some shortcomings that other machining methods haven't.Due to larger contact area between the grinding wheel and workpiece,the grinding heat is harder to come out.So the higher grinding temperature is its main shortcoming.Some negative effects on the surface integrity of workpieces and grinding wheels may occur due to its higher grinding temperature.In order to improve the performance of grinding,the surface structured grinding wheels were studied by researchers in recent years,and some research results have been obtained.In this paper,the concept of phyllotactic pattern in phytology was introduced into the design of grinding wheel with ordered grains which is one kind of the surface structured grinding wheels.Then,the grinding wheels with an abrasive phyllotactic pattern were manufacatured.Some studies and analysises of this kind of grinding wheel were conducted.The contents are as following:(1)Phyllotactic pattern is a result evoluted by natural selection through billions of years,so it must has some advantages that other patterns do not have.The uniformity of the phyllotactic pattern was studied from the aspects of circumferential direction and developed surface.The uniformity of the phyllotactic pattern was better.The essential requirement of the ordered grains on grinding wheel is to avoid too widely scattered or too concentrated,which is met by the phyllotactic pattern.In theory,the grinding wheel with an abrasive phyllotactic pattern should have good grinding performance.In order to verify the inference,the grinding wheels with an abrasive phyllotactic pattern were designed and manufacture using the lithography of masking technique and electroplate method.(2)The dynamic cutting points density of the grinding wheel with an abrasive phyllotactic pattern was studied.The dynamic cutting points density is an important parameter in grinding process,which is not only closely related to grinding surface quality of workpiece,but also has a great influence on the grinding processing.The model of dynamic cutting points density(Nd)using the grinding wheel with an abrasive phyllotactic pattern was established in this paper,which can be generalized to other engineered grinding wheels with orderly arrayed abrasive grains.The dynamic cutting points density over time of a grinding wheesl with ordered grains were figured out at different processing parameters using the established model.The mathematical expectation,amplitude and period of the dynamic cutting points density were analyzed and discussed in different conditions based on the model.The grinding wheel with the abrasive phyllotactic pattern has higher mathematical expectation,lower amplitude and no obvious change of period,which is expected in grinding.Finally,the influence of the phyllotactic coefficient on the dynamic cutting points density was analyzed based on the model.(3)Grinding surface roughness using the grinding wheel with an abrasive phyllotactic pattern was studied in the aspects of theory and experiment.One generally existing disadvantage of grinding wheel with ordered grains has been found by analyzing the related research status.Because of its lower grain density on account of its manufacture methods,its grinding surface roughness is lower than others machined by common grinding wheels.The model of grinding surface roughness using the grinding wheel with abrasive phyllotactic pattern was established,which is apply to other grinding wheels with ordered grains.Grinding surface roughness using the grinding wheel with an abrasive phyllotactic pattern is lower than others machined by other grinding wheels when they have same grain density.This is attributed to the better uniformity of the phyllotactic pattern.The relationship between the phylotactic coefficient and grinding surface roughness was also discussed and analyzed.(4)The study on wear of the grinding wheel with an abrasive phyllotactic pattern was conducted.Grinding wheel is one of the two main subjects in grinding process.The other is workpiece which has been studied in the aspect of grinding surface roughness.The working life of grinding wheel is influenced by the wear of grains directly.The wear images of grains were obtained by CCD camera and then were processed by computer program compiled by MATLAB.The wear areas of grains on grinding wheels after grinding canbe figured out using above processing method.The wear areas of different grinding wheels with same grain density were measured by this method.The grinding wheel with an abrasive phyllotactic pattern performed better than other grinding wheels in the aspect of grains wear.In order to analyze and explain this phenomenon,the finite element model of grinding fluid in grinding zone was built using CFD software.Finally,the relationship between the grains' wear and phylotactic coefficient was studied and analyzed.(5)The grinding force of the grinding wheel with an abrasive phyllotactic pattern was studied.The grinding force is a key parameter in grinding,which can reflect the energy consumption in grinding processing.The mathematical model of grinding force for grinding wheels with ordered grains was established based on the dynamic cutting points density,which was validated by the experiments.The grinding wheel with an abrasive phyllotactic pattern performed better in the contrastive simulations based on the established model and corresponding experiments in the aspect of grinding force.It means that this kind of grinding wheel can reduce consumption of energy in grinding.Then the relationship between phyllotactic coefficient and grinding force was studied through experiments and simulations.(6)The grinding temperature of the grinding wheel with an abrasive phyllotactic pattern was studied.The study of processing temperature is more important in grinding than other normal machining methods.That is because the grinding heat comes out hardly in grinding zone,which results in the increase of sensitivity for temprature.First,the grinding temperature theory of the grinding wheel with an abrasive phyllotactic pattern was analyzed and summarized.Then,the grinding temperature experiments of titanium alloy were studied contrastively using the measuring method of artificial thermocouple.The thermal conductivity of titanium alloy is low,so its grinding heat in grinding zone accumulates more than other material.According to its characteristics of generating less heat and dissipating more heat,this bionic grinding wheel performed better in the aspect of grinding temperature because of its lower grinding temperature in the comparative experiments between the grinding wheels with the same grain density.Then the change rule of the grinding temperature along with the phyllotactic coefficient was studied using experimental method.Finally,the conclutions were drawn from the studies and the suggestions of further studies were given based on this paper.