Andrejus Henrikas Marcinkevičius

Analysis of Influence of Different Kinds of Drills on Production Results

There at machining of parts on machining centers, different kinds of drills can be used for the same purpose. The best of them cannot be selected without necessary analysis. For that reason, different drills and their possibilities at machining of different length holes in parts are explored and their influence on machining results is showed in the paper. Because not only kind of a drill, but also the possibilities of a machine tool influence the final results, interaction of these components is analyzed.

Analysis of Optimization of Selection of the Tools for Turning

It was shown that selection of a tool and cutting rates has strong influence on machining cost. Influences of different expense components in a machining company are analyzed and it is shown how all of them influence of production cost and the smallest cost is searched. It is shown that adequate selection of tools for machining and rates of cutting can markedly decrease the machining costs.

Automatic Control of Loading Forces in a Tilting Pad Journal Bearing

Hydrodynamic three-tilting-pad journal bearing is analyzed. It is shown that a carrying force, stiffness of the bearing, and heat generated at journal rotation highly depend on a clearance between the journal and pads. The clearance can be controlled by measurement and control of hydrodynamic force at journal rotation. The bearing with such possibilities is described in the paper. Control of the hydrodynamic force prevents overheating of the bearing at large frequency of journal rotation, keeps necessary stiffness at small frequency of rotation, enables controlling forces loading the journal. Such a bearing is more versatile than being not controlled. Analysis and calculations are presented in the paper.

Theoretical Analysis of Vibrations of a Mass Connected with a Support through a Chain of Elastic Elements

Vibrations of a mass are analyzed when the mass is connected with the support in succession of two elastic elements characterized by stiffness and damping coefficients. It is demonstrated that upon harmonic excitation of the mass and considering different values of stiffness and damping coefficients the system can respond differently in comparison to the case when the mass is connected to the support by means of single elastic element. Reduction of stiffness and damping coefficients of a pair of elements to a single one (as it is proposed in calculations of considered systems) can lead to incorrect results. This is confirmed by presented calculations and dependences.

Research of Vibrations of a System with in Series Connected Elastic Elements Joining a Mass with a Support

Theoretical analysis of vibrations of a system in which the mass is connected with the support in series of more than one elastic element had shown that there is possibility to provoke additional resonances. Condition of it is change of damping values of the system near the supposed resonance frequency defined calculations. Feed mechanism of cylindrical grinding machine of older design was researched from that point of view. The mechanism consists of chain of elastic elements in series connecting the wheelhead with the bed of machine. Large friction forces exist in the chains of elements and in the wheelhead ways. Analysis results are presented in the paper.

A Computer Program Design for Optimization of a Cylindrical Traverse Grinding Operations

Traverse cylindrical grinding productivity and accuracy depend on many factors of rough, fine and spark out grinding. Evaluation of all these factors at manual calculation of the process plan is impossible, for that reason the engineer technologist selects the cutting rates approximately, and they are far from optimal. We have deduced equations for calculation of optimal cutting rates for that purpose. Because of task complexity the computer program was designed for calculations which is described in this paper.

Analysis of Work Accuracy Dependencies on Design of a Device for Control of Workpiece Dimensions and Compliance at Machining

Work accuracy dependencies of a new scheme device for automatic dimension control and follow rest at machining of multi step shaft are analyzed. The device can automatically reset from control and the support of one step of a shaft to the other and can be used on programmed cylindrical grinders or lathes. Errors connected with the kinematics scheme and showing in static and uprising at working of a device are analyzed and ways of their decreasing are shown.

Device for an Active Dimension and Deflection Control of Shafts at Machining

When using programmed machine tools many steps of a shaft are machined in one operation. Many shafts are not rigid enough and for the purpose of achieving high accuracy and productivity it is necessary to use an automatic follow rest and dimension control. The problem is complicated by necessity of an automatic reset in an operation from one step of a shaft to the other. The new scheme of a device is proposed in the paper that enables simultaneously to support the shaft being machined and control its dimensions. The work principle of a device is that the shaft is supported in a radial direction by a movable slider. Diameter of the shaft neck is measured by two levers turning round their axes driven by the movable slider with patterns. The main idea is that at motion of the slider equal to change of the shaft neck diameter measuring surfaces of levers are constantly tangent to diametrical surface of the workpiece while the slider is supporting the workpiece in radial direction, opposite to the cutting force. Dimension of a shaft neck is evaluated as a sum of motion value of a slider and deviation from tangent of lever measuring surfaces. Theoretical background of principle schemes and the work scheme of a device are presented in the paper.

Robotic grippers with accuracy centering fingers

A new design scheme of a robotic gripper for rotational family parts is presented and analyzed in the paper. The third or first class lever type of coupled fingers located from contrary sides of common longitudinal axis of symmetry of the gripper are used so that no less than two fingers from each side of the symmetry axis create an artificial centering prism. Distance of a centerline of the prisms, so the centerline of the part being handled, from the basic surface of the gripper is kept constant at changing diameter of the parts. Fingers are driven by a motion of sliders assembled inside of carriageways inclined to some angle to the symmetry axis of a gripper hand. It is shown that by keeping some rates of dimensions of mechanism elements straight lined finger surfaces will be kept tangent to the cylindrical surface of handled parts. Mathematical equations defining these rates are derived.