METHOD FOR CHECKING PRESSING OF CORE OF ELECTRIC MOTOR STATOR Russian patent published in 1998 - IPC

FIELD: electrical engineering. SUBSTANCE: method for pressing core of electric motor stator which has slots for winding and is made from steel sheets which are bound by means of pressing plates and clamping members involves detection of processing pressure by means of sequential mechanical pulse excitation in several sections along core length, measurement of current values of natural frequencies in these sections, measurement of average temperature of core and clamping members, calculation of processing pressure P in corresponding sections of corresponding using equation P = (f²/f2o

)P_o+α_c(t_c-t_oc)E_c-α_cm(t_cm-t_ocm)E_c, E_c, where f is first natural frequency of stator core, f0 is first natural frequency of stator core during first measurement, P0 is pressure which affects core during first measurement, α_c is index of core thermal expansion, α_cm is index of clamping members thermal expansion, t_c is current core temperature, t_co is temperature of core during first measurement, t_c is current temperature of clamping members, t_ocm is temperature of clamping members during first measurement, E_c is modulus of core elasticity which is calculated using equation E_c= (f²/f2o)E_co, E_co= 2πM(R₂+R₁)f2o/(R₂+R₁)², i.e. E_c= 2πM(R₂+R₁)•f²/(R₂-R₁)², where E_co is modulus of core elasticity during first measurement, M is weight of core back edge (in kg), R₁ is radius of stator core along slot bottom, R₂ is radius of stator core along back edge. EFFECT: increased reliability of assessment of density of bladed core, increased functional capabilities, increased efficiency of operations, simplified design. 3 dwg