Research Motor Capabilities of the Executive Authority (MP) PKM When Making Cross Motion Angle
Authors:   Central Ukrainian National Technical University, Pavlenko Ivan , Hodunko Maksym ,   Central Ukrainian National Technical University, Kyslun Oleg ,   Central Ukrainian National Technical University
Published: January 2021

For the manufacture of parts of complex shapes, it becomes necessary to move the cutting tool along the line at a certain angle. For this, machines equipped with mechanisms of parallel structure are used. Only a study of the movable capabilities of these mechanisms makes it possible to introduce them into production. The studies focus on the transverse movement of the center of the moving platform of the parallel structure mechanism for a hexapod machine, as a material point moving along a line depending on the angle of contact of the tool and the perpendicular to the plane of the work surface (axis of symmetry of the mechanism). To determine the possible positions of the center of the moving platform, we consider a generalized scheme of the parallel structure mechanism. Given the restrictions on movement, the area of possible positions is divided into zones: Zrp - without a cutting tool; Zri - the zone of positions of the top of the instrument. The part that is being processed is installed on the technological device, which is placed on the basis of a parallel structure mechanism. Parameters of a machine with a parallel structure mechanism: a, b - distance between the supports of the stationary carrier system and the executive body, respectively; Lmax is the maximum length of the kinematic links; lmin is the minimum length of the kinematic links; li is the current length of the kinematic links; l is the magnitude of the transverse movement; φ is the angle of inclination of the executive body; hi is the current position of the executive body of the mechanism of the parallel structure in height. The assessment of motor capabilities is determined by the displacement index, which is the ratio of the actual displacement value l to the theoretically possible one (taken equal to the maximum rod length Lmax). From the above dependencies it is seen that the influence of the motor capabilities of the rods on the relative displacement provides an increase in the displacement index in the indicator section from 0.45 to 0.65, then the section that is affected by the slope of the displacement line, with a decrease in which the displacement in the area of0.8 up to 1 movement decreases again, this is due to the complex geometry of the service area ofthe working space of the machine with a parallel structure mechanism. On the effect of the ratio of the sizes of the movable to the fixed platform on the relative displacement, we have that with an increase in the indicator, the initial indicator of the relative displacement also increases, with a value of the exponent n starting from 0.6 its value decreases in all cases. The influence of the ratio of the maximum displacement of the rods to the size of the fixed platform, on the relative displacement has the opposite of the previous character. With an increase in the indicator m, the relative displacement indicator increases, with a further increase in the indicator m, it can be seen that significantly decreases the displacement indicator and with a value less than 0.6.