mould oscillation is achieved through electro-hydraulic means in modern casters.
in the casters at my present work, these oscillator can have a frequency range of 25-300 CPM (Cycles Per Minute). the total stroke the cylinder piston is 50mm while during normal casting the range required is 8mm to 15mm maximum.
it is an easy logic that the oscillation should start at exact middle of the entire stroke; and target stroke should be distributed equally to the up and down side of this offset position of the cylinder.
it shall further be noted this offset position can be changed but should lie at the right position so that whatever oscillation is achieved should stay in line with the radius of the machine. this is necessary to avoid any external stress that may be exerted on the tender, weak shell inside the mould that may easily rupture.
these pics show a damaged valve stand that drives the cylinder up and down.
the first pic shows the LVDT placed inside the actuator piston of the hydraulic cylinder on top portion of the entire mechanism in the top of the image. the hoses below carry mould (inlet&outlet) and spray water of zone-1. the bob like structure positioned at an angle in the mechanism is an oil accumulator that helps in fast response to compensate for pressure drop inside valve or cylinder.
in the casters at my present work, these oscillator can have a frequency range of 25-300 CPM (Cycles Per Minute). the total stroke the cylinder piston is 50mm while during normal casting the range required is 8mm to 15mm maximum.
it is an easy logic that the oscillation should start at exact middle of the entire stroke; and target stroke should be distributed equally to the up and down side of this offset position of the cylinder.
it shall further be noted this offset position can be changed but should lie at the right position so that whatever oscillation is achieved should stay in line with the radius of the machine. this is necessary to avoid any external stress that may be exerted on the tender, weak shell inside the mould that may easily rupture.
these pics show a damaged valve stand that drives the cylinder up and down.
the first pic shows the LVDT placed inside the actuator piston of the hydraulic cylinder on top portion of the entire mechanism in the top of the image. the hoses below carry mould (inlet&outlet) and spray water of zone-1. the bob like structure positioned at an angle in the mechanism is an oil accumulator that helps in fast response to compensate for pressure drop inside valve or cylinder.
in the following image, cable that is from the LVDT (temposonic) is shown inside that round protection housing. the other two blocks of the mechanism just below that round housing show the actual valve (middleblock) and below that lies the moog controller block.
following closer image shows the same, but one can easily see the damaged valve block. this damaged was caused by excessive insertion of bottom-fed-dummybar. it travelled excessively up into the mould because of tracking failure from slipping withdrawal module motor-roll. the tracking is done using a rotary encoder attached to the motor.
it can be seen from the pics, the valve block has damaged along the ON-OFF valve connector on the left side while the right side ON-OFF valve stays intact. just above them at the middle lies one of the two pressure gauges that track the pressure built on the top side of the cylinder during oscillation. moog block makes this entire setup a SERVO VALVE whereby error tracking and correction in input command to the valve spool is done through inbuilt electronic circuitry to ensure the desired positions are achieved.
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