Crane, also known as crane, aerial crane, crane. Is a commonly used lifting equipment. This article mainly tells you about the operating mechanism and driving mode of the crane.
1. Operating mechanism of crane
Crane operating mechanisms generally only use four driving and driven wheels. If the lifting weight is large, the method of increasing wheels is often used to reduce wheel pressure. When there are more than four wheels, a hinged equalizing frame device must be used to evenly distribute the load of the crane on each wheel.
The metal structure of the bridge consists of main beams and end beams, which are divided into single main beam bridge and double beam bridge. The single main beam bridge consists of a single main beam and end beams located on both sides of the span, and the double beam bridge consists of two main beams and end beams.
The main beam is rigidly connected with the end beam, and wheels are installed at both ends of the end beam to support the bridge to run on the elevated frame. Rails are welded on the main beam for the operation of the lifting trolley. There are many types of bridge girder structure, the typical ones are box structure, four-truss structure and open-web truss structure.
The box-shaped structure can be divided into two types: normal rail box-shaped double beam, off-track box-shaped double beam, off-track box-shaped single main beam, etc. The box rail double beam is a basic form widely used. The main beam is composed of upper and lower flange plates and vertical webs on both sides. The trolley rail is arranged on the center line of the upper flange plate. Its structure is simple. It is easy to manufacture and suitable for batch production, but its weight is large.
The cross section of the offset box double beam and the offset box single main beam are composed of upper and lower flange plates and main and auxiliary webs of unequal thickness. The trolley rails are arranged above the main web, and the short stiffening in the box body The slab can be omitted, in which the deviated box-shaped single main beam is replaced by a wide-flanged box-shaped main beam, and the self-weight is smaller, but the manufacturing is more complicated. The four-truss structure is composed of four flat truss into a closed space structure. The upper horizontal truss is generally covered with a walking platform, which has light weight and high rigidity. However, compared with other structures, the outer size is large, the manufacturing is more complicated, and fatigue The intensity is lower and production has been less.
The open-web truss structure is similar to a deviated box-shaped main beam, which is composed of four steel plates to form a closed structure. Except that the main web is a solid-web I-beam, the remaining three steel plates are cut into many windows according to the design requirements to form a non-inclined rod The hollow web truss is covered with walking decks on the upper and lower horizontal truss surfaces. The crane operating mechanism and electrical equipment are installed inside the bridge frame. The self-weight is light and the overall rigidity is large. This is a type widely used in China.
Ordinary bridge cranes are mainly driven by electric power, which is generally operated in the driver's cab and also controlled from a distance. The lifting weight can reach 500 tons and the span can reach 60 meters.
The simple beam bridge crane is also called the beam crane, and its structural composition is similar to that of the ordinary bridge crane, with a small lifting weight, span and working speed. The main beam of the bridge frame is a simple cross-section beam composed of I-beam or other section steel and sheet steel. The hand-held hoist or electric hoist is equipped with a simple trolley as a lifting trolley. The trolley generally runs on the lower flange of the I-beam. The bridge can run along the track on the elevated, or along the track suspended under the elevated, this crane is called a suspended beam crane.
Metallurgical bridge cranes can participate in specific technological operations in the steel production process. The basic structure is similar to ordinary bridge cranes, but special working mechanisms or devices are also installed on the lifting trolley. The working characteristics of this crane are frequent use, harsh conditions, and high working level. There are five main types.
Simple beam bridge crane type casting crane: for lifting molten iron into a mixed iron furnace, steel making furnace and lifting molten steel into a continuous ingot casting equipment or steel ingot mold. The main trolley lifts the bucket and the auxiliary trolley flips the bucket and other auxiliary work.
Clamp crane: use the clamp to vertically transport the high-temperature steel ingot into the deep pit soaking furnace, or take it out and put it on the ingot truck.
Ingot crane: used to force the ingot out of the steel ingot mold. There is a special debonding device on the trolley, and the debonding method is determined according to the shape of the ingot mold: some of the ingot cranes use the bar to press the steel ingot and lift the ingot mold with large tongs; some use the tongs to press the ingot mold, use Small pliers lift the steel ingot.
Feeding crane: used to add the charge to the open hearth furnace. The lower end of the column of the main trolley is equipped with a pick lever, which is used to stir the material box and send it into the furnace. The main column can rotate around the vertical axis, and the pick lever can swing up and down. The auxiliary trolley is used for auxiliary operations such as furnace repair.
Forging crane: used to forge large workpieces with the hydraulic press. A special feeder is hung on the hook of the main trolley to support and turn over the workpiece; the auxiliary trolley is used to lift the workpiece.
Second, the driving method of the crane
It can be divided into two categories: one is centralized driving, that is, one motor drives a long transmission shaft to drive the active wheels on both sides; the other is separately driving, that is, the active wheels on each side are driven by one motor. Medium and small bridge cranes mostly use the "three-in-one" drive method in which brakes, speed reducers and motors are integrated. For large bridge cranes with common lifting capacity, universal couplings are often used for the drive device. .
