OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 5 1 3 Methods The fi rst task to achieve this purpose is to develop a technique for synthesizing the machine shaft drive, which allows designing a mechanism that improves the quality of the processed mixture. Below are the components included in the technique in the order of its solution. The fi rst is the structural synthesis of the mechanism, which provides a variable angular velocity of the working shafts of the kneading machine. The synthesis was carried out in the following order: as the fi rst group, providing a variable velocity of the working shafts of the machine, a cam group with a fi xed cam 1, a roller 2, a two-arm lever 3 was adopted; as the second, a rocker group was adopted, carrying a collet 4, movably fi xed on the second arm of the lever 3 and placed in the groove of the rocker 5 (Fig. 1). Due to the fact that in the proposed design the cam is fi xed, and the axis of the two-arm lever moves around the circumference, the synthesis of such a mechanism presents a certain diffi culty. In this regard, for the synthesis of this mechanism, it is proposed to bring a new model, assuming that the cam is movable, and the two-arm lever freely rotates relative to the fi xed axis (Fig. 1). To check the existence of a mechanism, the degree of its mobility using the Chebyshev formula [11] is determined. The degree of mobility of this mechanism was W = 2, which indicates the correct choice of the block scheme (an additional degree of mobility appeared due to the rotation of the roller around its axis). Getting to the second task of synthesis, we will carry it out as a parametric one. It is thought that in order to move particles of a crumbly mass, the working shaft with blades should be able to dwell in the upper position to create favorable conditions when moving the product from the upper layers down. Since the mechanism consists of a number of elements of kinematic pairs, the dwell time should be evaluated by the last link – the link, which sets the working shafts in rotation. Therefore, taking as a basis its angle of rotation, as well as displacement, speed and acceleration, the rational option that will satisfy the goal, can be chosen. For the case under consideration, this means the presence of a dwell, smoothness and continuity of the kinematic characteristics of the machine working shaft. The choice of the scheme of the mechanism is due to some already known design solutions of the drive, for example: the design of the working shafts, the location of the gears, the position of the engine and the design of the system carriers. Due to the fact that the cam mechanism is the fi rst to the rocker group, let’s begin the synthesis with it. In accordance with the works [12–14, 21], it is possible to accept the displacement of the center of the roller along the cycloid with the pusher journey H = 25 mm; the length of the rocker equal to L = 60 mm; cycloid angle β = 180°. It was adopted on the assumption that the period of the variable angular rate of the kneading rolls should be equal to half of its full revolution. The minimum radius of the cam ρmin, center distance a = OO1; initial angle ψ0 are proposed to be determined as the desired parameters in the process of the synthesis. Then 1 2 sin , 2 H h (1) where h is the current value of displacement; H is the maximum value of displacement; φ is the current value of the angle of the cam rotation; β is the angle of the cam profi le equal to 180°. This issue is presented in more detail in [12]. Fig. 1. General block scheme of the mechanism
RkJQdWJsaXNoZXIy MTk0ODM1