- Jun 11, 2013 -
First, a problem is put forward for the electrical automatic deviation system of the large span goliath crane.
One, the deviation is inevitable, that needs to do correction, as far as possible to minimize the deviation. A large deviation in the main span of Longmen crane: if the crane rail height and the parallel deviation caused by the running resistance of different wheel diameter deviation, deviation of the motor speed of the rigid and flexible legs after a period of operation will produce uneven phenomenon, usually when the error is close to span 3/1000, the crane should be automatic correction, the driver can also manually correcting according to the deviation indicator; when the deviation exceeds the 3/1000 span, deflection limiter can automatically disconnect the cart running control loop, the crane automatic parking.
Two, some commonly used electric automatic deviation methods:
It is necessary to analyze the causes and phenomena of the deviation, and then take corresponding corrective measures. There are usually the following methods of electrical automatic correction:
1, when the speed of motor on both sides of rigid leg and flexible leg is different, the average motor speed of the motor on the rigid side is faster than that of the motor on the side of the leg, which can be rectified by calculating the number of pulses of PLC input by the pulse coder.
2, the angle between the main beam and the soft leg is greater than or less than 90 degrees, which can be corrected by the angular displacement sensor mounted on the top of the flexible leg.
3, by comparing the first leg side cart wheel and a flexible leg side cart traveling wheel running line speed, which can be used in rubber friction wheel rotating encoder closed-loop control method to rectify;
4, directly install some induction points directly on the side rail of the rigid leg and the side of the flexible leg. The proximity switch is used to measure the actions of the proximity switch on the rigid leg side and the flexible leg side, and the input method is input to the PLC to rectify the deviation.
Three, the principle of electrical automatic deviation
1, basic programming and parameter setting method is calculated by pulse speed (soft) rigid leg side cart traveling wheel running distance using high performance proximity switch record crane rail plate number nut fixing bolts on the induction to determine the precise calculation (of course in the rigid and flexible leg side rail crane put some isometric electromagnetic induction point);
2, set up the first pulse sending side switch side, the actual operation speed is fast, this pulse signal will immediately enter the PLC input X17 (or X20), immediately record the speed and make automatic correction control.
3, automatic correction method is faster on the crane - such as the method of speed in the process of operation, soft leg fast, flexible leg side proximity switch induction to the first induction bolt nut on the flexible leg proximity switch control end by the normally open to closed, the attraction of a relay K510, PLC input X20 the input signal can be programmed to: LD X20, ANI X17, OUT Y17, then the control terminal of S9B soft legs inverter input speed control signal, 4 motor soft leg side immediately for deceleration, proximity switch when the rigid leg side also detected induction nut and bolt, can automatically break the input signal of S9B, the soft and rigid leg side motor and at the same time to speed and stable operation of the same;
4, such as crane during operation, just the leg side quickly, just the leg side close to switch to the first induction nut on the bolt, just close to the switch control end of the leg to normally open normally closed, the attraction of a relay K509, PLC input X17 input signal can be generated, program: LD X17, ANI X20 OUT, Y16, S9 just end when the control input inverter leg speed control signal, 4 motor just leg side immediately for speed, close to the switch when the flexible leg side also detected the nut on the bolt, will automatically disconnect the input signal S9, the rigid and flexible leg motor at the same time to speed and stable operation of the same;
There are many ways to correct the electrical deviation automatically for large span Longmen cranes, such as the global positioning system GPS, etc., but the cost of installation, debugging and maintenance is relatively high. The utility model has the advantages in simple circuit, sampling deviation components using 5-20mm and electromagnetic induction is the nut can work normally close to the switch, the switch protection level is more than IP67, there is no rotation, friction parts, long service life, installation and maintenance are very convenient.