机械毕业设计英文外文翻译金刚石刀具磨损的评价.docx

1、机械毕业设计英文外文翻译金刚石刀具磨损的评价Evaluation of diamond tool wearW.PoliniS.TurchettaReceived:28 May 2003/Accepted:9 January 2004/Published online:19 May 2004?Springer-Verlag London Limited 2004W.PoliniS.Turchetta(u)Dipartimento di Ingegneria Industriale,Universitdi Cassino,via G.di Biasio 43,03043 Cassino,Italy

2、 E-mail:turchettaunicas.it-0776-*AbstractThe present study proposes a test protocol regarding the wear of sintered diamond tools.A set of parameters which characterise the grade of wear,and its relationship with the cutting ability of the examined tools,are established.The proposed protocol establis

3、hes the procedure and the equipment for carrying out the tests,the features of the materials to use and the format of the report to present the results obtained.The developed test protocol indicates an universally applicable way for measurement of the wear of the diamond tool.It is an indispensable

4、instrument for correctly carrying out the wear tests and for reliably interpreting the results.The protocol developed so far mainly regards laboratory tests,considering the slowness and precision of the measurements involved.Given the total absence of norms,this protocol could be absorbed by nationa

5、l and international norm establishing organisations.This protocol has also been applied to two types of tools and the results obtained have appeared reliable and replicable.The test protocol proposed in this study makes it possible to overcome the difficulties connected to the scarcity of technical

6、data regarding the properties of the tool,which is typical in this field since the recipes for tool manufacturing are patented.Keywords Cutting toolDiamond sintered millMacro-geometric wear parametersTest protocolWear1 IntroductionThe increasing demand both in the industrial field and in urban furni

7、shing for elements in natural stone with increasingly complex geometry makes it necessary to use increasingly flexibleand automatic machines,such as numerically controlled machining centres.These centres make it possible to carry out large numbers of operations by means of diamond mills.No studies o

8、n optimisation of the cutting process have been carried out for these jobs.Therefore,until now,a sometimes imperfect solution has been accepted1,2.Optimisation means reducing machining costs and/or times and/or improving the quality of the products obtained by working on different factors,such as cu

9、tting strengths,tool properties,process temperatures and vibrations35.A critical point is the actual tool.Optimisation of the tool properties in relation to the wear process leads to optimisation of the whole process.The present study aims at understanding the diamond tool wear process.This behaviou

10、r has a direct influence on energy consumption and on tool life. In particular,diamond tool wear necessitates appropriate definitions and measurements.In other words,it is necessary to establish,in a clear and unequivocal way,the parameters that characterise the wear process and their measurement by

11、 means of a reliable and replicable procedure.The aim of the present study is to define a test protocol regarding wear of sintered diamond tools.The total absence of bibliographic references or norms regarding the procedures for conducting wear tests on sintered diamond tools has made it imperative

12、to prepare an adaptable test protocol that offers a universally valid mode for carrying out the macro-geometric wear test with the aim of obtaining replicable and comparable results.It is an indispensable instrument for correctly carrying out tests and for reliably interpreting the results.It offers

13、 stone machining companies the possibility of comparing tools that producers sell as being similar,but during machining present extremely differing performances.In fact,at the present state,diamond tools available on the market are characterised solely by the specification of the material they can p

14、rocess,while other technical features are subject to industrial patent and,therefore,are unknown to marble and granite machining firms.This protocol could be used by tool manufacturers to evaluate the performance of their tools compared to those of competitors and at the same time to equip their sup

15、- plies with information on the useful life of the tools offered.This last aspect represents a service that transformers are requesting with increasing insistence.The guide lines forming this protocol have been taken from existing norms for single-cut tools6.The protocol developed so far regards tes

16、ts to be carried out in the lab,given the precision and thus the slowness of the tests involved.The protocol has allowed the development of knowledge of the wear process of diamonds,which constitute tools for machining natural stones,which in turn constitutes the basis for machining optimisation.The

17、 following paragraphs describe the properties of diamond tools used in cutting natural stones and their relationship with wear.The test protocol and its application to two types of tools are described in the following sections.2 Wear of sintered diamond tools for machiningnatural stoneDiamond tools

18、used for natural stone machining can be classified in cutting tools,such as wires,blades,disks and mills, and tools for machining surfaces,such as grinders and mills of different shapes and profiles.In both cases the tool consists of a support,a super-abrasive grit and a bound.The support is the par

19、t of the tool upon which the abrasive grit is fixed.It gives the tool the appropriate form,transmits kinetic energy from the machine rollers to the abrasive grit and absorbs the strengths created during the machining process.The super-abrasive grit has the task of removing the material.Its propertie

20、s are granulometry,shape and bound matrix concentration.The granulometry expresses the measurement of the super-abrasive grit size.Theform of the grit may be regular or irregular according to the quality of the actual grain.Concentration is the quantity,in weight,of the diamond grit for sector unit

21、volume.The bound is that alloy which blocks the super-abrasive to the tool support so that it can carry out the cutting,milling,sharpening,smoothing and profiling economically and in a technically correct manner.The bound must guarantee two contrasting requisites:cutting capacity and long tool life.

22、Finally,the bound must have wear resistance suited to the type of tool super-abrasive,such as allowing the correct protrusion in relation to the process to be carried out and the features of the material being machined,but above all it must allow the loss of worn grit to encourage replacement by new

23、 grit existing within the matrix.The metals making up the bound mixture are iron,copper,tungsten,cobalt and nickel.The diamond tool wear is the result of the wear progression of both diamond grit and tool binding.It is characterised by a sequence of steps7,8. Firstly,there is a progressive increase

24、of grit protrusion with respect to binding surface,due to binding erosion,that makes the grit come into contact with the workpiece.An emergent crystal appears on the tool surface:its cutting ability is scarce because of its small height of protrusion.A binding that is too hard would make the abrasiv

25、e grit exposition so difficult the tool sector results polished before the diamond grits are completely emerged by binding.The progressive erosion of the binding makes the whole crystal appear on the surface of the tool sector.A whole crystal is a diamond grit that has a large height of protrusion a

26、nd a minimum surface damage.It has the best cutting performances.Once the workpiece is contacted,the grit is rounded off so much that a plateau is generated on the grit top.It generates mechanical friction and thermal effects that polish the diamond grits.An high percentage of polished grits makes t

27、he surface of the tool sector so vitreous,to cause a less efficient cutting ability.The intermittent contact with the workpiece,caused by the tool rotation,leads to a cyclic load on the diamond grit,which dete- riorates the grit ability to contrast the cutting forces and,finally, the grit breakage.T

28、his phenomenon is enlarged by the heterogeneous nature of the workpiece and by the machining vibrations. The diamond grits result is characterised by microfractures and microcracks that increase the number of cut edges on the grit surface,even if they reduce the penetration depth.Wear progression le

29、ads to a completely fragmentary particle or to a worn matrix in such a way that the diamond grit is released.The pull-out is the phenomenon due to the release of a diamond grit from binding, and to the consequent formation of a cleavage.It may accelerate tool wear,when a diamond grit is removed from

30、 the metallic binding before its useful life is completed.In this case the resulting cleavage will be very big and it will involve a considerable binding wear before a new abrasive grit emerges.Conversely, if the grit is removed from the metallic binding after its useful life is consumed,the cleavag

31、e will be less deep and less volume of binding will be consumed in order to remove a new grit.The pull-out is due to an increase either of the cutting efforts or of the cohesion power to keep fixed diamonds.New grits will emerge on the tool cutting surface and the wear cycle will begin again.The pro

32、gression of diamond tool wear consumes the diamond and the binding constituting the tool.This implies the decrease of both the weight and the diameter of the whole tool and the change of the cylindrical shape of the diamond tool.The tool moves away from its original cylindrical boundary surface.We h

33、ave evaluated the consumption of a diamond mill by means of four variables that depend on the whole tool:the decrease of the tool weight,the decrease of the tool diameter,the variation in the cylindricity of the tool shape and the grinding ratio.Cylindricity is a condition of a surface of revolution where all the points of the surfac