Ground turnover of objects
In production, due to the needs of processing technology and assembly technology, bridge crane drivers often encounter the operation of load turning objects 90 ° or 180 ° in the workpiece. There are two most common forms of overturning: one is ground overturning, and the other is air overturning. The ground turning is generally carried out with a single hook, and the air turning is carried out with the cooperation of double hooks.
1. Object rollover operation
Somersault is also called bottom somersault. This operation is applicable to some cast and forged rough parts that are not afraid of collision. The key points of its turning operation are:
(1) The hanging method of the overturned object shall be correct, and the rope shall be hung at the bottom or lower part of the overturned object. Generally, the locking point of the dead loop buckle is placed at the lower part of the overturned object away from the center of gravity.
(2) After fastening, push the handle of the lifting controller to gradually lift the hook. With the gradual inclination of the object with point a as the fulcrum, the position of the crane (or trolley) shall be corrected at the same time to ensure that the hook and the steel wire rope remain vertical at all times.
(3) When the overturned object tilts to a certain extent and its center of gravity exceeds the ground fulcrum a, the gravity overturning moment of the object causes the object to overturn by itself. At this time, quickly pull the controller handle to the first gear to lower the hook, so that the hook will drop the hook at the fastest speed. If the hook continues to lift at this time, it will cause the shaking of the object and impact on the vehicle body. This will not only hinder the overturning work, but also be very dangerous, so the hook must be dropped quickly in time.
When some machined parts are overturned by overturning, auxiliary ropes can be hung to prevent collision. The auxiliary rope shall be tied to the upper part of the object to be turned over, and the length shall be appropriate. Before the object is turned over, the auxiliary rope shall be in a relaxed state. When the object lifted by the hook is inclined gradually, the relaxation degree of the auxiliary rope decreases gradually. When the center of gravity of the object exceeds the support point a of the ground and the object can turn over by itself, the auxiliary rope is just tensioned and stressed. At this time, continue to lift, and the overturned object can be raised slightly to make it leave the ground. Then drop the hook. When the lower corner of the lifted object contacts the ground, continue to drop the hook to make the object turn over and fall to the ground gradually.
2. Object turnover operation
It is mainly suitable for the overturning and lifting of some disk-shaped or flat workpieces that are not afraid of collision damage. The operation essentials are as follows: according to the size and shape of the overturned object, first lift the overturned object that has been hung stably to a little off the ground, quickly start the cart or trolley, and manually start the lifting mechanism at the moment when the suspended object starts to swing to the maximum swing angle, so as to quickly lower the object at the fastest descent speed. When the lower corner of the overturned object contacts the ground, the hook continues to fall, and the object will turn over automatically under its own gravity. Stop falling immediately when the slack of the steel wire rope is enough, and quickly start the crane or trolley back to adjust the position of the vehicle body, so that the steel wire rope is in the vertical position after the overturned object is overturned. When swimming, prevent objects from colliding with surrounding equipment, grasp the turning time, and move quickly and accurately.
3. Overturning operation of objects
For some objects that are afraid of collision, such as processed gears, hydraulic control panels and other precision parts, the belt turning operation is generally used to turn over. During the turning operation, first lift the overturned object off the ground, and then stand up and slowly lower it. When the overturned object just comes into contact with the ground, quickly start the cart or trolley, and make the object turn around with the fulcrum a as the center through the horizontal component of the inclined and tensioned steel wire rope. When the center of gravity of the suspended object exceeds the fulcrum a, the object will dump itself under the action of heavy torque. When the overturned object dumps by itself, start the lifting mechanism to drop the hook, control its lowering speed and keep the hook vertical.
The belt turning operation is actually carried out by using the cable-stayed operation method of the operating mechanism. Such cable-stayed operation during turning is a normal operation and necessary for the process. However, the angle of oblique pulling during turning should not be too large. If it is too large to carry out turning operation, sleepers can be placed under the turned object to change the center of gravity of the lifted object.
The objects with overturning operation must be flat or disc-shaped objects. The center of gravity after lifting must be higher and the base surface at the bottom must be narrow. In addition, the hook must be kept vertical during operation, and the winch is not allowed to be lifted after the belt is turned over and the steel wire rope is tensioned at a certain angle, so as to prevent the steel wire rope from winding disorderly or falling off from the drum and being twisted and broken on the rotating shaft. Finally, when the object is overturned, the lateral movement of the vehicle body and the rapid descent of the hook should be coordinated.
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