Introduction of safety protection device for electric hoist crane

Hoist crane refers to the electric hoist lifting mechanism of the crane. Because of its simple structure, convenient operation and low cost, it has been widely used in machinery, chemical industry, light industry, railway and other industries. Because of the particularity of this kind of crane, the ground operator is often a person and several jobs, at the same time as the operation, the division, the command of the task, there are many unsafe hidden dangers in the operation.

In order to prevent such cranes from lifting injuries, GB6067-1985 "lifting machinery safety Regulations" and other relevant national standards have required that hoist cranes must have safety protection devices, such as stopper, end stop, buffer, safety brake device, etc. These safety protection devices have effectively improved the safety and reliability of the hoist crane, but due to design, manufacturing and production defects and other reasons, the hoist hoist safety protection measures are not perfect, According to the daily inspection experience, it is found that there are still defects or deficiencies in the wrong phase breaking phase protection, anti-breaking shaft protection, protection against electric hoist falling, buffer setting and so on.

A, wrong phase break phase protector. Because hoist crane uses three-phase asynchronous conical brake motor as a power device, and the direction of operation of three-phase asynchronous motor is related to the phase sequence of power supply, when the phase sequence of power supply changes, the motor's running direction is opposite to the original running direction, at this time press the "down" button, the spreader rises, and rises to the limit position restrictor does not work, It is easy to cause accidents. This kind of crane will occur every year due to the wrong phase caused by the collapse of the drum, the hook group extrusion deformation, steel wire rope broken accidents. At present, the CD, MD electric hoist produced and widely used in our country does not take wrong phase break phase protection measures (there is no requirement to install electric hoist). In order to prevent lifting injury accidents caused by misphase, a misphase and disphase protector is added to the electric control system of hoist crane.

When the power supply is out of phase or out of phase, the wrong phase out protection device works, so that the total power contactor is disconnected, and the crane can only continue to work after the power supply is restored to normal. In this way, it can not only prevent the crush of the drum caused by the wrong phase of the power supply, but also prevent the motor from being burned by the phase loss operation. Therefore, the function of phase fault protector is very necessary.

Two, anti-breaking shaft, derailment protection device. Electric hoist in the process of operation, due to the wheel rim and wheel tread wear, the gap between the wheel and the track gradually increases, at this time if you can not adjust the operating gap in time, electric hoist may fall off the track, causing lifting injury accident; At the same time, due to the particularity of wheel axle assembly, axle cracks are not easy to be found, cracks can not be effectively controlled, axle fracture may occur, resulting in falling accident. In order to prevent the resulting electric hoist falling accident, can be added in the appropriate position of the electric hoist to prevent breaking shaft, derailment protection device. When the electric hoist derailment or broken shaft occurs, the anti-broken shaft, derailment protection device can be effectively suspended on the track, so as to avoid the occurrence of lifting injury accidents.

Three, buffer. According to GB6o67-1985(lifting machinery safety regulations "provisions, in the electric hoist running terminal must be added buffer. Because of the installation position of the device is not clearly stipulated, the buffer of the electric hoist used in China is generally installed in the middle part of the I-beam. When the electric hoist running wheel and the buffer collision, the buffer plays the role of absorbing energy, but because of the particularity of the electric hoist structure, the running suspension wheel rim and the buffer collision, under the action of inertia, the suspension wheel rim makes the buffer wear is extremely serious. When the electric hoist runs for a period of time, the buffer will lose the original design function, so that the unsafe factors increase during the operation of the electric hoist, and the stability of the electric hoist operation drops sharply. In order to prevent the occurrence of this failure, the installation position of the buffer can be selected on the lower surface of the I-steel, using the buffer and the impact of the electric hoist hanging ear plate buffer, improve the safety and reliability, prolong the service life of the buffer.