V piece new sound of fixed position problem

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V piece it is one of fixed position cell that middling of machine tool clamping apparatus uses, with V model piece when fixed position, its fixed position is standard what be, still have difference at present. " mechanical engineer " 1996 the 3rd period, 1998 the 1st period all have this matter of article treat of, but viewpoint each different. Former think V piece fixed position is standard it is V model piece the osculatory generatrix with workpiece (next weighing that bus talks) , latter thinks to answer to regard fixed position as fiducial date receiving draft with the line of centre of turning circle of its workpiece 1998.


Say the center talks) below 07(. The author passes long-term education research, two kinds of viewpoints are narrated to all have inappropriate place before thinking, put forward oneself to be opposite now the new understanding of this problem, with colleague deliberate. 1 V piece the affirmatory V with standard fixed position piece it is a kind of more special fixed position component. Although it is component of an alone fixed position, but the structural element of its fixed position tool reference plane is not onefold however, have plane of two fixed position, the fixed position that will discuss this kind of form from some kind of meaning can regard the assorted fixed position that is two plane. Accordingly, its fixed position decides it is certain to cannot resemble analytic sheet fiducially a tool reference plane is simple in that way. The fixed position of component of most fixed position is standard it is the place that itself of fixed position tool reference plane perhaps forms by its, face, line, the central line that is like heart of onefold plane, ball, aperture and axis. According to this truth, the author thinks, v piece fixed position is fiducial and due two, it is two fixed position cross a line planarly firstly, another is the symmetrical median plane that forms by two plane, the fixed position that reachs a line to serve as perpendicular direction is standard; The fixed position that symmetrical median plane regards a level as direction is standard. According to the tradition (the center is talked) academic, v piece fixed position is standard should be to examine the center of arbor is high, examine namely arbor is in V piece on the central line when placing, actually this center line is in V piece inaccuracy cuts medium position, because its meeting examines size of arbor diameter error and change, accordingly, in the position error that introduces this center line to often be being met in knife error. If with V model piece the circle outside fixed position plane and workpiece contacts bus (bus is talked) for fixed position fiducial, because have the effect of common fixed position of tool reference plane of two fixed position, just make workpiece realizes correct fixed position, should make with the generatrix of that face so fiducial? Look this kind of method has not exact problem, this kind of viewpoint not only make the process of derivation of equation of fixed position error trival, complex, and formulary implication is not clear. As a result of V model piece the assorted fixed position that is two plane, cannot locate with what analyse the fixed position cell of onefold surface standard method will analyse its fixed position is standard. For example, workpiece with one side two aperture locate is component of commonly used fixed position is one side two annul, what two sold centers often regard the job as even the line is perpendicular the fixed position that asks even the position of heart line direction is standard, not be sell central line with some or outside round face makes his locate fiducial. The computation of the error of computational fixed position of error of 2 fixed position has synthetic law and ultimate position way commonly usedly two kinds of means, the author ever used formula of error of fixed position of function law derivation, the method is handier and practical. Ultimate position law and function law are when error of computational combination fixed position, having clear advantage. Graph 1 workpiece process chart     pursues 2 workpiece are in V piece on mill keyway still goes up to be a specification with cylinder workpiece here the derivation of formula of fixed position error (ask to be exemple) with upend direction size only. See a picture 1 workpiece process chart, keyway depth size can part with B1, B2, B3 3 kinds of means are tagged, cylinder diameter is set for D0dd. Graph 2 be in for workpiece V piece on the circumstance of fixed position, m is fixed position fiducial, o is cylinder center. Its locate error DB1, DB2, DB3 calculates as follows: Be opposite with ultimate position law B1 dimension, its working procedure is standard for A, fixed position is standard for M, accordingly, its error is the metabolic quantity of AM dimension namely, and so the α in DB1=dd/2[1/sin(a/2)-1] (1) type is AM=OM-OA={d/[2sin(a/2)]-(d/2)} V piece angle. Fiducial to the working procedure of B2 dimension for O, fixed position is standard for M, the working procedure of dimension of reason OM=d/[2sin(a/2)]dB2=dd/[2sin(a/2)] (2)B3 is standard for C, fixed position is standard for M, reason CM=OM+OC=(a/2)[1/sin(a/2)+1] criterion DB3=(a/2)[1/sin(a/2)+1] (3) uses function method the function form that this kind of method wants to build a requirement to assure dimension first namely, undertake differential next, cipher out machining error, among them one part is fixed position error. Pair of knife size should determine first when using this method, the fixed position of the person that traditional center is talked with workpiece is standard extremely knife piece regards pair of knives as dimension to the dimension of knife surface, the place before be like is narrated, this kind of method suffers as a result of central line position examine of arbor diameter error affect and do not decide, those who make its are broken is accurate, and two plane cross a line decide exclusively, reason is opposite with its D piece can be absolved to the knife to the dimension of knife surface examine the influence of arbor precision. Such function formula that we can establish B1, B2, B3 are as follows: The H in B1=BM-(OM-OA)=h-{d/[2sin(a/2)]-d/2}B2=BM-OM=h-d/[2sin(a/2)]B3=OM+OC-BM={d/[2sin(a/2)]+d/2}-h type is adjust (to the knife) dimension, these function type specifications fall in the condition that takes no account of other factor influence, depth size is right diameter of knife dimension, job, V piece the function of angle. We assume adjust an error for 0, v piece angle is absolutely precision, so keyway deepness is affected with respect to what get workpiece diameter bulk only, after differential, can reach conveniently (1) , (2) , (3) type. 3 conclusion are integrated afore-mentioned analysises, the author thinks V piece fixed position is standard choose two plane to make line and symmetrical median plane more reasonable, it can avoid to use already examine arbor and avoid to examine the diametical error to machining error influence of arbor, can undertake locating the analysis of the error is calculated conveniently again, undertake to clamping apparatus to use function method further the analysis lays next foundations machining precision. CNC Milling