Classificazione e caratteristiche delle gru a portale

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

Gru a portale
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. Trave reticolare
La forma strutturale saldata con acciaio angolare o trave a I presenta i vantaggi di basso costo, leggerezza e buona resistenza al vento. Tuttavia, a causa dei numerosi punti di saldatura e dei difetti della trave reticolare stessa, la trave reticolare presenta anche gli svantaggi di una grande deflessione, bassa rigidità, affidabilità relativamente bassa e frequente ispezione dei punti di saldatura. È adatto a siti con requisiti di sicurezza inferiori e capacità di sollevamento inferiore.

2. Trave scatolare
La piastra in acciaio è saldata in una struttura scatolare, che ha le caratteristiche di elevata sicurezza ed elevata rigidità. Viene generalmente utilizzato per gru a portale di grande e super-grande tonnellaggio. Come mostrato nell'immagine a destra, MGhz1200 è la più grande gru a portale in Cina con una capacità di sollevamento di 1.200 tonnellate. La trave principale adotta una struttura a trave scatolare. La trave scatolare presenta anche gli svantaggi di costi elevati, peso elevato e scarsa resistenza al vento.

3. Trave a nido d'ape
Generalmente si riferisce alla "trave a nido d'ape triangolare isoscele", la faccia terminale della trave principale è triangolare, ci sono fori a nido d'ape sulla pancia obliqua su entrambi i lati e ci sono corde sulle parti superiore e inferiore. La trave a nido d'ape assorbe le caratteristiche della trave reticolare e della trave scatolare e ha maggiore rigidità, deflessione minore e maggiore affidabilità rispetto alla trave reticolare. Tuttavia, a causa della saldatura delle piastre di acciaio, il peso proprio e il costo sono leggermente superiori a quelli delle travi reticolari. È adatto per siti o depositi di travi utilizzati frequentemente o con capacità di sollevamento pesante. Poiché questo tipo di trave è un prodotto brevettato, esistono meno produttori.

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.