Electromagnetically driven presses are efficient in processing mineral raw materials (mica, sheet mica, etc.), making briquettes and tablets, as well as in engineering. Optimized design of this equipment and determination of optimum operation regimes requires analysis and calculation of the dynamic characteristics of the force-pulse system consisting of the electromagnetic drive and the load. We will first consider a system using a cylindrical electromagnet with two running clearances (Fig. 1). The dynamic processes in the system are described by nonlinear differential equations:where E is the emf of the source; R, winding resistance; i, current; ~b a, magnetic flux linkage; h a, depth of armature in the winding; Fea, traction force of the electromagnet; Fsa, string force opposing the pulling of the armature into the winding; Ffa, force of friction; ga, free-all acceleration; Foa, external opposing force; t a, 9 time; m = mar + m0, mass of moving elements where mar is the armature mass is the m 0 is the moving mass of the rigging.The subscript a indicates absolute values. Subsequently, it will be possible to distinguish these values from the corresponding relative values. Since in electromagnetic presses the armature and the yoke of the electromagnet are made with maximum clearances, the effects of eddy currents are disregarded. The validity of this assumption is confirmed by experimental data.In order to determine the current, the magnetic flux linkage, and the traction force as functions of the position of the armature and the core saturation, a prelimInary calculation of the magnetic circuit of the press drive is necessary (Fig. 1). The magnetic system is represented as a complex of two serially coupled magnetic lines of the lengths l I and 12 with distributed parameters which are separated neutrally (the cross section A-A) and the area of the corresponding clearance 6 located inside the winding. The solution of magnetic llne equations given in [1] has the form:(21 where @x and V x are the relative magnetic flux and voltage in the cross section M at the distance x from the neutral; F, relative magnetomotlve force per unit length of the winding; r = r2/r i, ratio of the outer and inner radius of the winding; @, H, relative values of the functions for x = 0; H = H t + H', relative intensity of the magnetic field on the neutral equal to the sum of the intensities of the yoke and armature fields.For the baseline values we choose x b = r i ;where B b = 1T is the basal value of induction; Saratov Polytechnic Institute.
