Crawler crane is a mobile crane for material lifting, transportation, loading and unloading, etc. It is one of the most important main cranes in loading and unloading equipment. This crane has the advantages of large lifting capacity, low ground specific pressure, multiple combinations of booms, and carrying with load. It is widely used in large-scale construction projects such as water conservancy, electric power, petrochemicals, ports and bridges.
In order to achieve large lifting weights, we need to design and produce very large crawler cranes. In order to give full play to the boom performance of large crawler cranes, an extra lifting device can be added to the existing crane. This can expand the scope of use of the crane and improve the utilization rate of the crane.
1 Type of super lifting device
Super lift is a boom-type super mast installed between the mast (herringbone) and the boom to improve the geometric relationship between the boom and the cable. At the same time, the super mast is connected to the super lifting weight, which increases the whole machine. Stability, thereby improving crane performance. There are two commonly used forms of super-lifting devices: one is a trailer-type super-lifting device, which replays all the super-lifting devices on a counterweight trolley. The stability of the whole machine is always in the best state, and changes in working conditions are simple to implement. , The counterweight trolley can walk or revolve synchronously with the host on the ground; the other is a suspension type super lifting device, the superlift counterweight must be off the ground during the operation, otherwise the host cannot perform walking and revolving operations. In general, the trailer type super lifting device has high requirements on the ground. It needs to be able to meet the weight of the trolley. It is suitable for operation on a good ground in a shipyard. Of course, the trailer type super lifting device can also be used as a suspension type. . Suspension type super-lifting device only requires that the flatness and strength of the ground where the super-lifting weight is parked can be satisfied. However, using the suspension type super lifting device, the lifting weight and working range must match the super lifting counterweight weight and the super lifting counterweight range so that the counterweight can be guaranteed to leave the ground for walking and turning operations.
2 Super lifting device operation process
The super-lift counterweight trolley of the trailer type super-lifting device has its own function, so the matching relationship between the lifting weight and the super-lift counterweight need not be as strict as the suspension type. Even if all the super-lift counterweights are installed, the crane can not be used in the lifting range. Restricted lifting, luffing, walking and turning, simple operation.
´ó²¿·Ö Most domestic cranes are configured as suspension type super-lifting devices. There are various forms of luffing and lifting of super-lifting counterweights, each with its own characteristics.
According to the operation process of the super lifting operation, the installation of the non-cylinder type super lifting device is simple and quick, but there are many precautions during use, and the operation technology is difficult; the horizontal + vertical cylinder type super lifting device has a complicated structure, high cost, and time-consuming assembly, but Easy to use, flexible operation, and can realize stepless luffing of super-lifting counterweight; horizontal cylinder type is simpler to install and lower cost than the former, but its performance is similar to that of non-cylinder type, but it can be stepless after the super-lifting counterweight is off the ground Luffing; the vertical oil cylinder type super lifting device is relatively horizontal and vertical oil cylinder type with simple structure, low cost, almost assembling time and convenient use.
Through the analysis of the operation process of the super-lift operation, the following points need to be done in the design process of the crane super-lift device:
1) The fretting performance of the crane is better, and the minimum stable speed of single rope is not more than 2m / min;
2) The maximum amplitude and minimum amplitude of the main horn are limited. Force sensors can be installed on the horn rope or the main horn pull plate;
3) The super lifting device with vertical oil cylinder needs to be equipped with a pressure sensor to detect whether the forces on the two pull plates are balanced, and the force situation of the two is displayed on the display screen. The user can choose to operate the two oil cylinders synchronously or adjust them separately;
4) An angle sensor needs to be installed on the super mast, and its amplitude is used to calculate the amplitude of the super mast;
5) If the horizontal cylinder type can be steplessly changed, a length sensor needs to be installed, otherwise a positioning pin can be used at a certain range to ensure the width of the super-lifted counterweight.
The high cost performance of Langzhong's large tonnage cranes equipped with super lifting devices can greatly improve crane performance. At present, China has just begun to manufacture large-tonnage crawler cranes, and the design of the super lifting device is still in the exploration stage. Analysis and research on the super lifting device and operation of foreign large tonnage crawler cranes will be very helpful to our design and development.