БИБЛИОТЕКА
Increase of efficiency of
diamond grinding of hard alloys with electroerosive influence on a working surface
of a emery-wheel
Strelkov V. (masters work)
The modern machine industry shows high tolerance requirements, productivity and life expectancy of details of an article, which operation indexes to a great extent depend on quality of finishing operations. In this connection use of diamond wheels is one of the most effective ways of a finish machining intractable of materials.
The quality of a treated surface at diamond grinding depends not only on correct assignment of conditions of cutting, constructions of wheels, but also ways of their editing, and also quality metal ligament. If ligament strongly keeps diamonds - occurs greasing of a circle, poorly keeps - diamonds not executing operation, pass in a swaft.
The existing constructions of diamond circles consist of the aluminium case and diamond containing of a ring, that results in heightened expenditure of a material of the case of aluminum, as in tool pantries are a great many of circles which are not used in a production cycle.
The unproductive losses of diamonds can arise and while in service, when, for example, is carried out infeed grinding one circle of details of different length. In this case, at editing ledge, the diamonds which are not carrying out process of cutting are deleted. The marked deficiencies can be eliminated by application of modular wheels, and also electroerosive method of editing, as is considered in offered to operation, in which the questions of improvement of constructions of wheels and ways of their editing for increase of efficiency of diamond grinding difficult-to-cut of materials are decided.
In operation on a foundation of the carried out analysis of modern constructions of diamond wheels, their virtues and deficiencies are detected. With the purpose of liquidation of deficiencies the decision of manufacture of circles modular was accepted. The opportunity of manufacture of circles modular is justified by research of efforts in fast-rotating a ring - calculated efforts much below admissible.
With the purpose of development of an optimum construction of a circle the existing constructions of modular wheels are considered. All considered constructions are developed on mechanical faculty Donetsk state technical university. Their virtues and deficiencies are analysed. In result in a new construction, on not ё the patent application is sent, it was possible to remove the majority of deficiencies of the previous constructions. For the given circle the technique of definition of forces of fixing of a ring on the case is submitted, and also technique of definition of efforts in the case and ring by the account of forces of fixing (in the case of effort) are diminished by 1-2 %, in a ring are augmented by 1 %). The economic benefit of use of a modular wheel makes one dimention-type of a series 300 mm on height on 100 circles more than 2000 relative units.
The analysis of ways of editing has shown, that optimal a way of editing - electroerosive.
The modernizing of the existing machine tool 3V642 is from the point of view of an economic efficiency more favourable as contrasted to by acquisition of the new cost intensive equipment. The essence of modernizing consists in security of reliable isolation of the grinding head from nodes of the machine tool. Admission of a technological current in a cutting zone is carried out from a source of a technological current ИТТ-35. The mechanism of migration of an electrode along a surface of a circle ensures 10 double strokes in mines, the drive is checked on power, that speaks about serviceability of the mechanism.
With the purpose of reduction of expenditures of time by searching of optimum conditions of handling at grinding, the way in which is offered the dependence for definition of magnitude of an average current of electroerosive effects (request for the invention is shown: a way of grinding in the co-authorship with Matuha P.G., Poltavecs V.V. Griniov A.А.). At use of this method the complexity of definition of optimum conditions of grinding is diminished on 30-40 of %.
The handling can be carried out under two circuits: elastic and rigid.
The grinding under the elastic circuit has advantages, as allows to eliminate influence of a temperature component, and also influence of a wear of a circle.
For holding experiment by definition of influence of force of a hold-down tool of a circle on the size of platforms of a wear of diamond grains modernized planogrinding the machine tool of model 3G71, as a result of the carried out(spent) experiments is detected, that the influence of a run time on magnitude of platforms of contact of diamond grains can be circumscribed by the equation of an aspect, thus the magnitudes of platforms of a wear for different forces of a hold-down tool of a circle differ unsignificantly. At speckles 100/80 and 250/200 after 30 mines of handling the magnitude of platforms of a wear also varies unsignificantly.
Research infeed grinding of diamond grinding have shown, that use of electroerosive effect at grinding samples, which magnitude on length is less than height of a circle, augments probability of origin ledge. Accordingly for exception of this harmful influence it is necessary to use wheels with regulated height.
On a foundation as stated above it is possible to make an output, that the efficiency of grinding can be increased at the expense of manufacture of wheels modular, and also use of electroerosive editing.
In this connection in the further operation the following tasks should be decided(solved):
1. Manufacture of a pilot model of a new modular wheel, holding full-scale of trials, definition of required force of fixing, definition of efforts in fast-rotating a ring, and also development of strengthening of a ring on the case, for exception of a distortion at installation on the case, development of strengthening of the case of a circle on flanges.
2. Manufacture of the mechanism of editing, and holding of trials in real environment, definition of optimum conditions of editing of diamond circles with use of the given construction.