Automatic fault diagnosis of the hottest automobil

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Auto welding equipment fault diagnosis and welding machine group control system

we designed and implemented a set of equipment fault diagnosis and welding machine group control system for the welding workshop of Shanghai Volkswagen No.2 plant, using SIMATIC products of Siemens. After several years of use, the system runs stably and reliably, and basically achieves the design purpose

I The welding workshop mainly produces the body of Santana 2000 car. The workshop feeds various stamping parts from the stamping workshop. After the welding production line, these various parts are welded and assembled into various body parts, such as the front wall, rear wall, front floor and other parts of the car, and then these parts are welded into an integral body through assembly. Finally, the final body in white is formed through repair welding and grinding, and is output to the paint workshop for painting. According to the welding process of stamping parts - components - General Assembly, the welding workshop has established six production lines, including front contour line, rear contour line, front bottom plate line, bottom plate line, general assembly line and repair welding line. The six production lines are rigidly connected with each other according to the production process. Each station on these production lines is mainly equipped with automatic equipment such as welding manipulator, welding robot, multi-point welding machine, pull rod transmission and air transport vehicle. 44 sets of PLC of Siemens company control various processing equipment on these production lines respectively to make them operate coordinately, continuously and automatically, so that the workshop can achieve the production beat of producing a BIW every 56 seconds

however, when the production line of the workshop is put into operation, there are two main problems:

1. When a fault occurs somewhere on the equipment, because it cannot be quickly eliminated, the whole production line is often shut down, or the whole workshop is shut down, which seriously affects the workshop output and production efficiency

2. the welding quality of some welding points will be unstable, which cannot guarantee the quality of BIW

after investigation and specific analysis, the main reasons for the above problems are:

1. There are many equipment on the production line, the equipment is relatively complex, and the production lines are rigidly connected. If a mechanical, hydraulic or electrical fault occurs at a certain part, it will cause a production line to stop. The maintenance personnel need to go through a certain period of analysis and search process to find the fault point and eliminate the fault. In the time of fault analysis, search and elimination, because there is no buffer between the production lines, the front production line will stop immediately, and the rear production line will cause empty stations. If this time is too long, it will also cause the rear production line to stop. The time of fault analysis and troubleshooting is mainly the time of analysis and troubleshooting

2. There are more than 2000 electric welding guns working at the same time in this workshop, which is easy to cause voltage fluctuation. If some electric welding guns are powered on and welded at the low voltage, it is easy to cause the welding spot to be improperly welded and of poor quality

therefore, in order to quickly analyze and find faults and ensure normal voltage power on welding, and solve the above two problems, we have established this set of equipment fault automatic diagnosis and welding machine group control system for the workshop

II The hardware and software structure of the system

1. The equipment layer

there are 44 PLCs in six production lines in the whole workshop, which are composed of Su, Su and su. These PLCs can provide the system with relevant information to analyze the operation status of the equipment and analyze the fault points. But these PLCs are decentralized and have no fault diagnosis ability. Therefore, our system has established two sections of PROFIBUS in the workshop to connect these PLCs respectively. The system can collect and summarize the equipment status information on the production line through the on-site PLC, and automatically analyze and diagnose the fault. The specific method of equipment merging is to insert PROFIBUS card cp5431 into each PLC and connect it to one of the field industrial buses. (see the attached figure)

2. The field engineer station

the field engineer station is set at the workshop site, which is composed of six industrial computers, corresponding to six production lines at the workshop site respectively. These six industrial computers are respectively inserted with PROFIBUS card cp5412, which is connected to PROFIBUS. The corresponding production line can be monitored through the on-site engineer station. (see the attached figure)

3. Information exchange center

generally, the information exchange center is composed of a Su, also known as the main PLC of the system. On the one hand, 44 PLCs on the production line are connected through the workshop field industrial bus PROFIBUS to collect, summarize and analyze the fault information of the equipment on the production line; On the other hand, connect with the management of the system through industrial Ethernet H1, which is not only connected to the Chinese market, and send the analysis and diagnosis results to the office computer spring testing machine for the detection of leaf springs. At the same time, send the analysis and diagnosis results back to the field engineer station through the workshop field industrial bus PROFIBUS. (see the attached figure)

4. The management of the management

system includes the computers in the workshop director's office and the maintenance office, which are connected through the industrial Ethernet H1 information exchange center, so that the management can obtain the current analysis results from the information exchange center in real time, classify and archive them, and form various reports. (see the attached figure)

5. The welding machine group control device

is equipped with a highly sensitive voltage monitor to monitor the change of power supply voltage during the operation of the welding machine in the workshop in real time, and send the results to the information exchange center. The welding machine group control information is processed through the s5-155u interrupt program, and the control signal is transmitted to the PLC on the production line at high speed through the prifibus DP mode, so that the power on operation of the corresponding welding machine can be controlled

In addition to a series of problems caused by components

6. The system configuration software

coros lsb/win is the main software of the system, which mainly runs on the computers of the management and field engineer stations, and is the main development platform of the system. Com5431 and com143 system software are used to manage Profibus and industrial Ethernet H1

III The main purpose of the system

1. Collect the equipment operation status information of six production lines in the whole workshop

because PROFIBUS is connected to the on-site PLC, the system can monitor and distinguish the current normal operation of each production equipment in real time

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