Slewing mechanism

Abstract

The invention relates to a slewing mechanism and particularly relates to a slewing mechanism for the fields of tower cranes. The invention provides the slewing mechanism which is simple in structure and low in cost, and is capable of realizing stepless speed adjustment, stably starting and braking and reducing impacts to a crane boom and a tower body. The slewing mechanism comprises an alternative current (AC) motor, a slewing speed reducer, an electromagnetic eddy clutch, an electromagnetic eddy brake, a middle electric pivot, an electric control system and an operation platform. During starting, the middle electric pivot is smoothly started by virtue of the comprehensive actions of the electromagnetic eddy clutch and the electromagnetic eddy brake; the inertial impact during starting is avoided; during braking of the slewing mechanism, the brake time of the slewing mechanism is prolonged by virtue of the electromagnetic eddy clutch and the electromagnetic eddy brake; the stable transition of the slewing mechanism from a motion state to a motion state is realized and the impacts to the crane boom and the tower body during braking are reduced.

Description

technical field [0001] The invention relates to a slewing mechanism, in particular to a slewing mechanism applied in the field of tower cranes. Background technique [0002] The slewing mechanism of the tower crane has the following characteristics: the slewing mechanism is the most direct transmission mechanism affected by the inertial impact of the tower crane. The longer the boom, the greater the end hoisting load, the greater the moment of inertia, and the greater the inertial impact. Since the slewing mechanism of the tower crane is a whole that drags the upper part of the tower crane, it is generally required to run at full speed in about 7 seconds during work, and to stop stably in about 7 seconds. During mid-stop, although the slewing motor loses power and stops running, the forearm and rear arm of the tower crane still continue to decelerate and slew under the action of huge slewing inertia, causing the hanging object to slide past the destination in a short time an...

AI Technical Summary

Problems solved by technology

Since the slewing mechanism of the tower crane is a whole that drags the upper part of the tower crane, it is generally required to run at full speed in about 7 seconds during work, and to stop stably in about 7 seconds. During mid-stop, although the slewing motor loses power and stops running, the forearm and rear arm of the tower crane still continue to decelerate and slew under the action of huge slewing inertia, causing the hanging object to slide past the destination in a short time and cannot fall accurately. The operator of the tower crane should jog and stop a certain distance in advance according to experience, and even reverse the car to get in place

[0003] In the prior art, the start of the slewing mechanism is controlled by a stepped speed control mechanism and a hydraulic coupler, resulting in a large torsional impact of the whole machine, a long time for the boom to slide after the motor is powered off, it is difficult to position, and the slewing reducer is easily damaged

Moreover, the slewing mechanism of the tower crane has the following technical problems: the output shaft of the gearbox is often twisted and broken, which seriously affects the normal operation of the equipment and increases the maintenance cost and number of maintenance; The impact is large, which seriously threatens the operation safety of the steel structure and reduces the service life of the equipment itself; the tower body twists seriously when parking, and is accompanied by shaking, which makes the tower crane driver obviously feel that the operation is not stable, unsafe and reliable; although Frequency conversion control can solve the above problems, but the cost is high, the control is complicated, and the technical level is high.

Therefore, in the prior art, there is no slewing mechanism with a smooth starting and braking process, which can reduce the impact on the boom and the tower body, and has a simple structure and low cost.

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