门式起重机的分类及特点

According to the structure of the door frame, it is divided into gantry crane and cantilever gantry crane

龙门起重机
1. Full gantry crane: the main girder has no overhang, and the trolley is carried within the main span.
2. Semi-gantry crane: The outriggers have a height difference, which can be determined according to the civil engineering requirements of the site.

Cantilever Gantry Crane
1. Double cantilever gantry crane: The most common structural form, the force of the structure and the effective use of the site area are reasonable.
2. Single cantilever gantry crane: This structural form is often selected due to site constraints.

According to the main beam form
1. Single girder gantry crane
The single main girder gantry crane is simple in structure, easy to manufacture and install, and its own weight is small. Most of the main girder is a partial rail box frame structure. Compared with the double girder gantry crane, the overall rigidity is weaker. Therefore, this form can be used when the lifting capacity Q≤50t and the span S≤35m. There are two types of L-shaped and C-shaped gantry legs for single girder gantry cranes. The L-type is easy to manufacture and install, has a good stress condition, and its own mass is small, but the space for hoisting goods through the outriggers is relatively small. The C-shaped leg is made into an inclined or curved shape, and the purpose is to have a larger lateral space so that the goods can pass through the leg smoothly.

2. Double girder gantry crane
The double main girder gantry crane has strong bearing capacity, large span, good overall stability and many varieties, but its own quality is larger than that of the single main girder gantry crane with the same lifting capacity, and the cost is also higher. According to the structure of the main girder, it can be divided into two forms: box girder and truss. At present, box-shaped structures are generally used.

According to the main beam structure

1. 桁架梁
采用角钢或工字钢焊接而成的结构形式具有成本低、自重轻、抗风性能好等优点，但由于焊接点多及桁架本身的缺陷，桁架梁也存在挠度大、刚度小、可靠性相对较低、焊接点检查频繁等缺点，适用于对安全性要求不高、起重能力较低的场地。

2. 箱梁
钢板焊接成箱形结构，具有安全性高、刚性大的特点，一般用于大吨位、超大吨位龙门起重机。如右图MGhz1200是国内最大的龙门起重机，起重量可达1200吨。主梁采用箱形梁结构。箱形梁也有成本高、自重大、抗风性差的缺点。

3.蜂窝梁
一般指“等腰三角形蜂窝梁”，主梁端面呈三角形，两边斜腹有蜂窝孔，上下有弦杆。蜂窝梁吸收了桁架梁和箱梁的特点，比桁架梁刚度大，挠度小，可靠性高。但由于采用钢板焊接，自重及成本较桁架梁略高。适用于使用频繁或有较大起重能力的场地或梁场。由于此梁型为专利产品，生产厂家较少。

by purpose
1. Ordinary gantry crane
This kind of crane mostly adopts box type and truss type structure, which is the most widely used. It can carry various pieces and bulk materials, with a lifting capacity of less than 100 tons and a span of 4 to 39 meters. Ordinary gantry cranes with grabs have a higher level of work. Ordinary gantry cranes mainly refer to hook, grab, electromagnetic, hoist gantry cranes, and also include semi-gantry cranes.

2. Gantry cranes for hydropower stations
It is mainly used for lifting and opening and closing gates, and can also be used for installation operations. The lifting capacity is 80-500 tons, the span is small, 8-16 meters; the lifting speed is low, 1-5 meters per minute. Although this kind of crane is not frequently lifted, once it is used, the work is very heavy, so the work level should be raised appropriately.

3. Shipbuilding gantry cranes
It is used to assemble the hull on the berth, and there are always two lifting trolleys: one has two main hooks, running on the track of the upper flange of the bridge; the other has a main hook and an auxiliary hook, which is on the lower flange of the bridge run on rails for flipping and hoisting large hull sections. The lifting capacity is generally 100-1500 tons; the span is up to 185 meters; the lifting speed is 2-15 meters per minute, and there is also a fretting speed of 0.1-0.5 meters per minute.

4. Container gantry crane
For container terminals. After the trailers transport the containers unloaded from the ship by the quay wall container carrier bridge to the yard or rear, they are stacked by the container gantry crane or directly loaded and transported away, which can speed up the turnover of the container carrier bridge or other cranes. The yard that can stack containers with a height of 3 to 4 layers and a width of 6 rows is generally of the tire type, but also of the rail type. Compared with the container straddle truck, the container gantry crane has a larger span and height on both sides of the portal frame. In order to meet the transportation needs of the port terminal, this kind of crane has a higher working level. The lifting speed is 8-10 meters per minute; the span is determined by the number of rows of containers that need to be crossed, and the maximum is about 60 meters, corresponding to the lifting capacity of 20 feet, 30 feet, and 40 feet long containers, which are about 20 tons and 25 tons respectively. and 30 tons.