The article contains research of the dependence between the maximum elastic exertion of a scraper chain
pull in case of its jamming and the drive current value of the conveyor drive's electromagnetic slip coupling.
Multiple investigations of the scraper conveyors work have shown that the hydraulic start-preventing
coupling decreases its reliability. Expel-ling of the hydraulic couplings and usage of a regulated electric drive will not only
help to increase reliability of a flight conveyor but also get a few of other advantages like controlling speed and exertion of
the flight chain in different work modes.
A regulated conveyor drive based on electromagnetic slip couplings has been already created. Such drives
are reliable, easy to control and quite reasonably priced.
However, the flight chain jamming process is also followed by sys-tem overloading, just as it happens
when hydraulic couplings are used. This article contains research results on the influence of the drive currant volume in the
electromagnetic slip couplings on the maximum effort of elastic tension in case of a flight chain jamming.
Picture 1 - Dependence between a flight chain's speed, elastic exertion ef-fort and time parameter when chain is jammed
A mathematic model was worked out for this research. It is described by the following equations:
when w1 - shaft speed of a conveyor driving star wheel; F - rated effort of a drive; i - control current of a coupling field coil; Q - drag chain deflection rate; ΔL - chain jamming extension; m1 - stated mass of a conveyor's electric drive; Um - field coil voltage, a, b - constant coefficients.
Picture 2 - Correlation between the maximum elastic effort and decelera-tion time with different coupling field coil current volumes
So it is clear that elastic tension depends on the electromagnetic slip coupling drive current volume. If it is timely decreased, dynamic overload decrease will be reached up to 50% in 0,35 sec deceleration time and up to 25% in 0,2 sec.