Laser detection for high-quality body welding

The visual inspection station has high measuring speed and high precision, and can realize on-line real-time monitoring of the process of the body assembly and the subassembly, so that the status of the production line can be timely and effectively reflected, and the production equipment can be adjusted in time to reduce the occurrence of waste products, and eventually improve. product quality.

Welding is one of the important processes in the automobile manufacturing process, and it has a very high technical specification. Therefore, the welding quality must be well tested. The traditional detection method usually uses a coordinate measuring machine. However, this method is complicated to operate, has a slow speed, and has a long cycle, and can only perform spot inspection on a workpiece. As a new detection method, visual inspection has many advantages such as large range, non-contact, intuitive, rapid, and high precision, so it can be applied to the on-line detection of automobile body and timely feedback of product error information, which not only improves the qualified rate of products, At the same time, it provides a closed-loop feedback size control method for process improvement and error reduction, which is in line with modern manufacturing quality engineering requirements. Figure 1 shows a block diagram of a universal vision inspection system in which the vision probes are various types of vision sensors.

Laser vision inspection system

The key dimensions of the vehicle body are mainly the size of the windshield, the position of the edge of the door installation, the position of the positioning hole, and the positional relationship of the subassemblies. Therefore, the visual sensor is mainly distributed near these positions and measures the corresponding edges and holes. The spatial position and size of the surface are generally fixed measurement systems. A measuring station is designed on the production line. The positioned body is placed in a frame. The frame is composed of vertical and horizontal metal columns and rods. The visual sensor can be flexibly installed on the frame according to the need. The number of sensors is usually determined by the number of measured points. At the same time, according to the form of the measured points, the sensors are usually divided into binocular stereo vision sensors, contour sensors and other types.

1, working principle

In practical applications, usually a plurality of visual sensors form a visual inspection station. Each sensor first calculates the coordinates of the measured point in the current sensor coordinate system, and then converges all the visual sensor coordinate systems in the system coordinate system. To complete the measurement. The work of the system is mainly based on the camera model and the three-dimensional measurement model of the stereo vision sensor.

In order to obtain the coordinates of the measured point in the vehicle body positioning coordinate system, it is necessary to use the standard coordinate system as an intermediary to convert the coordinates of the measured point in the sensor coordinate system to the measured point in the body positioning coordinate system. This requires sensors. The coordinate system and the car body positioning coordinate system are together with the standard coordinate system and are called the intermediary coordinate unity method.

The above work is accomplished through a process of local calibration and global calibration. Local calibration uses the lens perspective principle to calibrate 12 external parameters from the world coordinate system to the sensor three-dimensional coordinate system; the global calibration adopts the intermediate coordinate system scheme (Figure 2). By using the target, the corresponding sensor for the measurement is obtained. Sensor coordinate system to theodolite coordinate system transformation matrix, complete the unity of the coordinate system.

2. Advanced digital control system

The laser vision detection system adopts advanced CBVM monitoring and control software, which can realize all the functions of the inspection station through the graphical operation interface. Even unskilled operators can use it conveniently. At the same time, the data management and analysis software is responsible for the management of measurement data and the completion of the query and analysis of measurement data by LAN users.

(1) Vehicle data query and analysis

The query of the entire vehicle data is based on the entire vehicle body and reflects the condition of the entire vehicle body.

The entire vehicle data query can be queried according to the production time of the vehicle body, and can also be queried according to the number of the vehicle body. The list of query data can be used in a variety of sorting ways: body number and point number, point number and body number, production time, and production shift. The data display uses three different background colors to reflect the measurement error of the measurement point.

(2) Functional Size Analysis

Functional size analysis is a comprehensive evaluation of multiple points of a vehicle body.

The body can be selected for a certain period of time for functional size evaluation, or a certain number of bodies within the body number segment can be selected for functional size evaluation. The evaluation table lists the body number, the production time, and the functional dimensions. The data in the table can be sorted according to the selected functional size item, or the graphical display (Figure 3) can be selected.

(3) Statistics function

The inspection data statistics for the product quality of the entire production line can be divided into monthly statistics and annual statistics: For monthly statistics of daily products, statistical conditions can be selected. For example, statistics for the month, unqualified quantity, etc., the form of the chart display can be The qualified rate can also be the daily output; the annual statistical quantity is based on the monthly statistical quantity, so after each month's data is counted, it will appear in the annual statistical form.

Application of laser vision inspection station

With the continuous improvement of the level of automobile manufacturing, laser vision inspection stations have gradually been applied. FAW-Volkswagen Automotive Co., Ltd. has adopted this system for dimensional control from each assembly. Parts with problems will be discovered, alarmed, and replaced in time. Repair area. This ensures that the components of each stage are assembled from lower-level assemblies that are qualified. Not only that, because the data is detected and stored in real time, when problems are discovered, the manufacturing department can quickly find out where the problem of fixtures is and adjust them in the shortest time (Figure 4).

Fig. 4 The application of visual inspection system in welding assembly

In addition, the laser vision inspection system is also widely used in welding production, such as door cover assembly, front-end cutting and welding, as well as the formation of the rear taillight positioning holes at the rear of the vehicle body.

In the traditional process, the lamp mounting holes are welded with a plurality of stamping parts (as shown in FIG. 5 ). The accumulated errors are relatively large and difficult to control, resulting in poor matching quality and dimensional instability after installation of the rear tail lamp. Using laser vision inspection technology, punching is performed after the fitting welding of various parts is completed. By using the laser on-line measurement, the left and right profile of the rear tail lamp is formed into a digital model, and compared with the digital model already stored in the controller. The best match size and adjust the robot to complete the punching process.

Figure 6 shows an example of laser in-line inspection technology applied to the white body door assembly. The robot-controlled pick-up and laser on-line detection system are controlled via the bus to form a closed-loop system. The real-time dynamic measurement of the lid assembly process through the laser on-line inspection system enables real-time measurement of measured data and standards in the processor. Digital-analog data comparison, given the deviation of the measured value and the theoretical value, real-time adjustment of the installation position of the pick-up to achieve a design of the best value, then the flatness and clearance of the door and side will reach a maximum Good value.

Conclusion

The application of advanced laser on-line inspection systems in various fields of automobile manufacturing has, to some extent, changed some of the traditional manufacturing processes in automobile manufacturing. It has important implications for promoting the development of the automobile manufacturing industry.

SLS-Selective Laser Sintering technology, using 3D Printing materials: PA Series Nylon 3D Printing Material: Abrasion Resistance, High Strength and Stiffness, Good Chemical Resistance, Excellent Long-term Invariant Behavior, High Selectivity and Detailed Analysis, Biocompatibility in accordance with EN ISO 10993-1 and USP, and in accordance with EU Plastics Directive approved for food contact. Typical applications of this material are the highest quality of fully functional plastic parts. But the surface is relatively rough. There are also PA3200GF nylon fiberglass materials for deep drawing dies or any other applications requiring specific stiffness, high thermal deformation temperature and low wear; typically used in aluminium-filled nylon materials for metallic appearance and thermal load parts. At present, desktop LS laser sintering PA12 nylon powder material is also an option. 

Selective Laser Sintering

Selective Laser Sintering,3D Printing Pa Material,Auto Door Accessories Parts,Selective Laser Sintering Prototype

Ningbo Expert Mould Plastic Co., Ltd. , https://www.prototypesmaker.com