摘 要

现代社会迅猛发展,我国随着社经济的不断发展,科学研究的不断开拓，使得如今市场竞争更加激烈，起重机也由于自动化技术越来越先进，技术变革与日俱进，使得其运用更加广泛，规模也更加宏大因此起重机生产企业都希望改进生产技术，提高生产效果和效率，制造行业也对起重机的要求更高，性能方面也趋于全面。

本设计为桥式起重机的小车运行机构的设计，所谓起重小车是指沿着小车轨道行驶，其吊钩做垂直升降运动的工具。它的工作范围是在行驶范围内所形成的长方体领域，起重机在车间的工作应用很广泛。起重机小车有四个行走轮，在布置其上的零部件时，应使机构重心接近小车架的纵向中心线，这可以使得最后拥有均匀的轮压。

在最开始，确定小车运行机构为闭式齿轮传动的传动方案，减速器与电动机直接相连，减速器在在小车中间的运行机构；其次：通过对小车运行机构部分的总体设计计算，以及车轮、联轴器、制动器、减速器、缓冲器、电动机等的选用和计算；完成小车运行机构的设计。通过一系列的设计，满足起重量达到40T 的要求。

关键词：起重小车，设计，联轴器, 运行机构

Abstract

With the rapid development of modern society, with the continuous development of social economy in our country and the continuous development of scientific research, today's market competition has become more fierce, and cranes have become more widely used due to advanced automation technology and technological advances. The scale is also more ambitious. As a result, crane production companies all hope to improve production technology and improve production efficiency. The manufacturing industry also has higher requirements for cranes and more comprehensive performance.

This design is about the trolley running mechanism of the bridge crane. The so-called lifting trolley is a vehicle that runs along the trolley track and whose hooks perform the vertical lifting movement. Its scope of work is in the field of cuboids formed by driving, and its application in the workshop is extensive. The crane trolley has four running wheels. When arranging the components on it, the center of gravity of the mechanism should be close to the longitudinal centerline of the small frame, which can result in a uniform wheel pressure.

At the very beginning, it is determined that the trolley running mechanism is a transmission scheme with a closed gear transmission. The speed reducer is directly connected with the motor, and the speed reducer is in the middle of the trolley. Secondly, through the overall design calculation of the trolley running mechanism part, and Selection and calculation of axes, brakes, buffers, motors, etc. verification calculations, structural designs and design calculations of parts of the reducer of the operating mechanism, the design of the trolley running mechanism is accomplished through a series of designs to meet the weight requirements up to 40T.

Keywords: lifting trolley, design, reducer, operating mechanism

Contents

Statement of Originality i

Copyright Letter of Authorization to The Dissertation i

Abstract iv

Chapter 1 Introduction 1

1.1 Preface 1

1.2 Research Status at Home and Abroad 1

1.3 Future research directions 2

Chapter 2 Introduction of Bridge Cranes 4

2.1 Composition and Features of Bridge Cranes 4

2.2 Development Trends of Bridge Cranes at Home and Abroad 5

2.3 Bridge crane trolley 6

2.4 Bridge crane trolley operating mechanism 10

Chapter 3 Trolley running mechanism design 11

3.1 Requirements for Designing a Trolley 11

3.2 Trolley running mechanism transmission scheme 13

3.2.1 With open gear transmission scheme 13

3.2.2 Closed gear transmission scheme 14

3.3 Select wheels and tracks and check their strength 17

3.3.1 Choose wheel 17

3.3.2 Intensity Check 17

3.3.3 Calculation of operational resistance 19

3.3.4 Select The Motor 21

3.3.5 check the heating condition of the motor. 22

3.3.6 Selection of speed reducers 22

3.3.7 Validation of operational speed and actual power requirements 23

3.3.9 Checking the power of the reducer according to the starting condition. 25

3.3.10 Checking the starting non-slip condition. 25

3.3.11 select the brake. 27

3.3.12 select high-speed shaft coupling and brake wheel. 27

3.3.13 select low speed shaft coupling. 28

3.3.14 Test for low speed floating shaft strength 29

Chapter 4. Selection of trolley frame 31

4.1 To determine the type of trolley frame 31

4.2 To determine the structure of the trolley frame. 31

5.1 Summary 33

5.2 Deficiency 33

References 35

Appendix………………………………………………………………………………………...36

Acknowledgement……………………………………………………………………………….39

Chapter 1 Introduction

1.1 Preface

40T bridge crane sure has a lot of advantages: 1. When the crane is working, each mechanism is usually in the alternate working state of starting, braking and forward and reverse. 2. Can improve the work efficiency of the organization, and the load capacity is also very strong. 3. The work is stable, has information control technology, and has strong control ability.

1.2 Research Status at Home and Abroad

As China is the largest developing country in the world and a major manufacturing country, the scale of industry is continuously expanding, production efficiency is highly increasing, work intensity is high, working conditions are strict, and energy consumption and reliability are high. China's manufacturing industry is prosperous. China has now become the largest exporter of small-tonnage crane products on the basis of having already owned the world's largest crane market. In the case of exporting small tonnage cranes, China is already superior. However, in the case of oversized tonnage cranes, China’s competitive advantage is insufficient. Technical breakthroughs related to oversized tonnages are currently the crux of the problem.

Another problem is that when the crane removes the payload from the ground, the payload may slip or swing. This motion occurs when the load is not directly under the lifting point of the hoisting cable. Considering that the cable suspension point can be several hundred feet above the payload, it is difficult for the crane operator to know if the sling is vertical so that the payload can be lifted from the ground.

With the dramatic increase of China's economy, cranes have performed very well in industrial production. At present, there are more than 3,500 hoisting machinery equipment manufacturers in China, of which 1,898 have more advanced manufacturing capabilities, including during the "Twelfth Five-Year Plan" period. The gross industrial production value and sales revenue of heavy machinery products increase by an average of 30% each year, but there is still a big gap between the overall performance of products and foreign countries. Hoisting machinery in China since the early 50 s to create, has formed a certain scale of production, has the certain technical level, and basically formed a relatively complete system of design, production, sales, can basically meet the demand of national economy of the device. At present the country continue to implement fiscal policy, drives the rapid development of infrastructure construction in our country, and lifting equipment as the important infrastructure of national economy is widely applied in the economic construction in all path of life, such as metallurgy, coal, chemical industry, electric power, transportation and manufacturing industries. With the rapid development of modern science and technology, the expansion of industrial production and to increase the degree of automation, crane is more and more widely used in the process of modern production, the effect will also become more and more larger and it is also beneficial to the requirement of crane production. The lifting machinery is developing in the direction of large scale, high speed, humanization, environmental protection, miniaturization of general products, modularization and diversification of components and safety supervision.

 The cranes follow the modular design. Currently, the U.S., Japan, Germany, the UK, and France all adopt crane modular design solutions, and they are effective in this area. For example, German Demag has reduced the cost by nearly 50% due to its modular design. The economic benefits are very considerable and there is a trend of rapid development. On the basis of modularization, it also follows simplification, light weight, and a wide range of crane applications. Some areas do not require very large loads, so organizations should be streamlined to achieve maximum economic benefits; the current trend of cranes is also developing like intelligence and automation. Advanced computer technology has brought new directions to the electrical control and transmission of cranes. New programmable controllers and digital drives can be used to form new electrical control devices. The cranes will also be developed systematically, centrally controlled, coordinated with production systems, and integrated with production equipment.

1.3 Future research directions

From the perspective of the overall industry, foreign countries are leading for more than 10 years but, less than 20 years. The speed of economic development in foreign countries is now slowing down and becoming stable. In the future, cranes will develop into smart, high-performance, more flexible, multi-functional, more adaptable, and develop in the direction of large tonnage. Basically, no more than 30 tons of cranes will be produced. For example, Liebherr's cranes can no longer continue to compete in the market. Currently, the minimum tonnage of cranes that dominate the market is 32 tons, and many are even 70 tons and 150 tons. In addition, there are many differences between the industry support and the domestic market. The vehicle is basically a diesel engine with a power of 300 kW or more, which is matched with a hydraulic torque converter, an automatic shift transmission, and a 12-ton steering axle; Slewing bearing and high torque hoisting mechanism, high-strength material; Suspension system valve, balance valve, variable motor, hydraulic cylinder and pipe standard fittings, hydraulic system selection variable pump, solenoid reversing pilot valve and main valve, hydraulic pressure Lock; intelligent control system using memory communication, single-cylinder sequential telescopic automatic control and force limiter display control. Such as Bellinger's balance valve, pilot valve, main valve; Rexroth's valve, lifting, pump motor, traveling mechanism, rotary, pilot valve; PAT's force limiter Hawe's main valve, balancing valve; Caselan's Bridge; ZF transfer case, gearbox, etc.

Chapter 2 Introduction of Bridge Cranes

2.1 Composition and Features of Bridge Cranes

A crane is a multi-action lifting appliance that vertically lifts and horizontally lifts heavy objects within a certain range. Also known as cranes and aerial cranes. The crane is one of 7 types (cars, passenger cars, trucks, tractors, special vehicles, dump trucks, and off-road vehicles) classified according to the use of automobiles.

There are many kinds of cranes. From the perspective of structure and performance, there are four types: bridge type cranes, cable cranes, light and small lifting equipment, and boom type cranes. It can also be subdivided into bridge type, arm type, self-propelled type, tower type, cable type, and so on. From the lifting point of view, the crane can be divided into three types: tower cranes, mobile cranes, and mast cranes.From the drive point of view, can also be divided into separate drive and centralized drive, the so-called separate drive means that the active wheels on both sides are each driven by a motor, and centralized drive is to use a motor to drive long drive. The shaft drives the active wheels on both sides. It can be seen that the crane has a wide range of applications and a large application area.