SU112300A1 - Electromechanical boom crane capacity limiter - Google Patents

Description

The electromechanical limiters of the lifting capacity of the jib cranes, equipped with a spring mechanism, take up the load from the tangential component of the tension of the jib booms and transmit the displacement caused by this load to the next system controlling the actuator of the limiter, news.

Load limiters installed in the hoisting hoists cannot take into account the effects on the crane stability of the boom weight, wind loads, crane roll, as well as the inertia of the boom during cornering. These loads can take into account the load limiters installed in the boom hoists, however, the inconvenience of the value of the hoist when lifting and lowering the boom causes these limits to cause significant faults.

The magnitudes of the forces acting in the boom rods, c-pushojushchie to connect the free end of the boom with the movement of the chain pulley, do not depend on the value of the efficiency of the polyspast. The magnitude of these efforts is influenced by the weight of the boom, wind loads, and crane roll to the horizon.

The proposed limiter takes into account all the listed loads. A special feature of lero is that a Wheatstone bridge with lateral arms formed by resistors is used as a follower system, the slider of one of which moves through the hinge-lever system from the polyspath, the slider of the second from the spring mechanism, and an executive relay is included in the diagonal of the bridge. triggered at current values in the diagonal close to zero.

FIG. 1 shows a diagram of a boom of a crane with an electromechanical stopper of load-bearing capacity in two projections; in fig. 2-diagram limiter capacity.

For the operation of the limiter, two rheostats were used, connected according to the scheme of the Wheatstone bridge, using a relay that operates at a current of

№ 112300

diagonal, close to zero, and not making a reverse connection at a current opposite to the specified direction, but automatically turning on the control circuit Ui after the crane overload is removed.

The tared coil spring / restrictor (Fig. I) has a linear characteristic. The resistance resistor 2 is installed directly near the spring. The rheostat slider moves by an amount proportional to the amount of compression or spring expansion under the influence of a tangential force T. Rheostat (Resistance 3 is installed near the cantilever jib of the boom polyspast on the tower head or portal gantry, the rheostat slider moves the hinge-lever device 4 by an amount proportional to the maximum the allowable compression or tension of the spring when the maximum allowable force is applied to it for a given angle of inclination of the astrel ropes to the horizon. Relay 5 breaks the Ui controlling the mechanisms for lifting and moving the load when the coil is de-energized and when the current is inverse to the specified direction. The calculation and construction of the limiter is performed as follows: determine the tensions of the boom rods under the weight of the load methods. Based on the obtained tension value S, the maximum allowable value of the force acting on the spring Tdon-is determined. The calculation is carried out for several sorties. According to the received maximum Tdo „, the spring is selected or calculated and the value of its maximum draft is obtained. Draw a graph of spring sediment, depending on the angle p. This graph will be the graph of the movement of the gl engine (Fig. 2) of the rheostat 3 mounted on the head of the crane tower or the portal gantry.

In accordance with this, device 4 (ftlg-1) is performed, which ensures the displacement of the rheostat slider when the angle changes by the corresponding value. Moving the same engine rheostat 2 is associated with the draft of the spring /. The work limiter is as follows. When lifting a load, the weight of which is equal to the limiting one, established for operation on a given boom angle, the spring will be compressed by the maximum permissible value. In this case, the g slider moves along the rheostat by an amount equal to -dop. Thus, the bridge will be balanced and the potential difference between the slider g and gi will be equal to zero. Relay 5 is triggered and switches off the mechanisms for lifting the load and moving the crane. The re-activation of the crane mechanisms will be possible only after the load is lowered to the ground and the engine g is returned to its original position. The adjustment of the load limiter is made by lifting the load (10% larger than the nominal one) 10-15 cm from the ground, after which the screw sets the slider gi slider to the position at which relay 5 operates. When the operating conditions of the crane change (setting and removing the counter-load, changing the boom), the adjustment is repeated.

Subject invention

The electromechanical load limiter of the boom cranes with a spring mechanism that perceives the load of the tangential component of the tension of the stretch pulls and transfers the displacements caused by this load to the following system that controls the executive body of the limiter, characterized in that on cranes without their additional alteration, the Wheatrton Bridge with lateral arms formed by rheostats, the engine of one of