Bridge crane design (load capacity 8 tons, span 11 m)

Contents

Contents

Introduction

1. Overview of Existing Designs

2. Source Data

3. Calculation of cargo lifting mechanism

4. Calculation of trolley movement mechanism

5. Calculation of bridge crane movement mechanism

6. Calculation of crane reliability

7. Safety precautions

List of used literature

Introduction.

The purpose of this course project is the structural development of the bridge crane, as well as its mechanisms according to the specified parameters. Bridge crane mechanisms include cargo lifting mechanism, trolley movement mechanism and crane movement mechanism. During design, you must analyze existing designs and select a machine layout. After that perform basic kinematic and strength calculations. Then perform preliminary development of the general type of machine. After that, structural development of separate mechanisms and assemblies with strength and reliability calculations is carried out.

A bridge crane is a lifting machine that moves along rails at a distance from the ground (floor) and provides for the movement of cargo in three mutually perpendicular directions.

Bridge cranes are the main lifting equipment of production workshops, closed and open warehouses. As a load-gripping element of cranes are: hooks, grabbers, electromagnets (general-purpose bridge cranes), grips and other special devices (special bridge cranes). Moving along the tracks located above the ground, they do not occupy the useful area of ​ ​ the workshop or warehouse, while providing service, at any point.

The lifting capacity of bridge cranes reaches up to 500 tons, spans - 60 m., Lifting height - 50 m and in a special design - 600 m. (mine crane). Speed (m/s): bridge movements 0.5-2.5, trolley movements 0.1-1, cargo lifting to 1.

The bridge crane includes two main parts: a bridge and a trolley. The bridge consists of a metal structure covering the working span of the production room or warehouse, and a movement mechanism by which the crane moves along the crane track. The trolley consists of a frame, one or two load lifting mechanisms and a movement mechanism by which the trolley moves along the rails along the bridge. Bridge movement mechanisms are made with a separate drive (on each side of the bridge), for small spans - with a central drive. With large drive capacities, two movement mechanisms on each half of the bridge are provided in responsible cranes.

The movement mechanisms of freight trolleys are similar to the movement mechanisms of bridges.

The main parameters of the crane include: lifting capacity, span, base, hook lifting height, cargo lifting speed, crane and trolley speed, track, and trolley base, operating mode, crane and trolley weight.

Safety of cranes operation is provided by load limiters, height, lifting, crane and trolley movement, as well as buffer devices. The weight of the crane affects not only its cost, but also the amount of investment in the construction of a building or trestle due to the need to use building elements (columns, crane beams) of appropriate sizes. The vertical dimension of the crane determines the height and cost of the part of the building located above the crane tracks, and other dimensions and the distance from the hook raised to the upper position to the steel structure of the crane are the dimensions of the volume of the production room served by the crane.

In order to improve the safety of operation, cranes should be painted in colors that differ from the surrounding objects and attract attention.

Monitoring the work of cranes shows that over the past 20 years, the intensity of the use of cranes has increased by more than 2 times. At that time of mechanisms operation without load is equal to time of their operation with loads, and time spent for suspension of load and release of hook is from 30 to 50% of time of full cycle at manual slinging. Therefore, the number of cycles does not exceed 1520 per hour.