Bar companies have formed a consensus on building an intelligent production line through learning advanced technology and conducting technical exchanges. advanced questions. Summarized the experience of improving the operating efficiency of unmanned cranes, which can adapt to the refined production requirements of the industry, and built an industry-leading intelligent manufacturing platform.
1 The main problems in the bar production line
At present, the types of mechanical equipment in the bar production line are small and intelligent, and it is impossible to carry out remote centralized control. Intelligent centralized management is required. Specifically, the following issues need to be addressed:
(1) The steel billet has not passed the quality control before entering the furnace, and it is easy to mix in bad steel billets, thereby affecting the production and quality of the product; the surface detector for small and medium-sized bars can only be used for bars with low rolling speed. For material surface inspection, the instrument is backward, and the error of the inspection result is large.
(2) There are currently two types of ring bar and wire rolling, one is welded and the other is cast-rolled. The predecessor of headless welding technology — Italy Danieli has developed to the third generation, need to solve the problem of speed matching of heating furnace and grinding machine, peeling effect and stable operation of equipment; the latter includes steel production system and continuous casting which are difficult to realize.
(3) Although the device for controlled rolling and controlled cooling is used, the alloy is suitable for the controlled rolling and controlled cooling of the reduction of steel bars according to the new national standard, and the quantification needs to be further explored.
(4) Less investment in diameter measuring instruments, most of which are manual sample diameter measurements, which brings high safety risks and lags behind problem discovery and resolution, which often leads to product deviation.
(5) Various control rooms are scattered throughout the production line, occupying a large number of employees, and the control rooms must be connected to realize remote centralized control. The basic functions of the automation system need to be divided, and there is an urgent need to improve the accuracy of management. Big data production systems and advanced custom models are missing. The production line itself must be able to adapt, reducing product changeover times and responding to system tolerances.
(6) Cooling bearing equipment has low steering accuracy, slow braking, many accidents, and insufficient capacity. In addition, the cold shear capacity is very poor with the capacity of the cooler and the inspection table, resulting in low steel yield and reduced long-term rate.
(7) The intelligence level of the inspection table is relatively lacking, which leads to poor overall efficiency, increased error rate, and high labour costs because all work needs to be done manually. Moreover, the equipment of the collection device on the inspection table is always of poor quality and poor efficiency due to insufficient clamping force, and the current inventory robots and industrial robots are only in the initial stage of use, so it is necessary to increase the utilization rate. Further planning is required.
(8) The overall warehouse is in a chaotic state, the cranes are too old, and there are too many administrators and operators in the chaotic situation, resulting in a very chaotic stacking area, which is caused by poor management, Did not make a reasonable plan for the entire warehouse management. This leads to an increase in the rate of finding and damage of warehouse materials and products, as well as the rate of forgetting, resulting in the inability to make good use of resources. Therefore, if the above problems can be improved, the production progress can be greatly improved, a new intelligent steel rolling control system can be formed, and the pass rate of products can be increased by 1%.
2 Intelligent transformation plan of the bar production line
2.1 Overall Improvement Plan
Add necessary equipment and intelligently transform existing equipment. The production line management system is divided into two levels of computer management. The first layer can realize the corresponding control between equipment, production process control and data collection, the second layer can realize production plan management, air temperature monitoring, report generation technology and Internet detection technology are all included, which is to ensure the safety of products The quality and control platform is a great convenience. With the foundation laid by such technology, the problem of warehouse management chaos can be solved, a new era of intelligent warehouse management can be realized, the application of manual labour can be gradually reduced, and unattended operations can be included in the new agenda. The strict control of product accuracy, production volume and remote control requirements on the bar production line can be of great help, and a new intelligent warehouse management system will gradually form.
2.2 Selection and development of surface detectors
Surface defects can be detected by an infrared surface defect detection unit, but the maximum detection speed is only 1m/s. By connecting surface defect detection to the rolling mill production line, the surface defects of rolled products can be detected and removed or retained according to process requirements, thereby improving the internal quality of rolled products. The BKVision meter monitoring system from the Baker Institute of Technology can perform beam numbering, square automatic length measurement and automatic beam recognition of special shapes, and can also detect surface defects in rebar. The detection speed is 0m/s~20m/s, according to the different light reflection characteristics of different areas on the bar surface, a unique green light source is used to assist the industrial camera and scan the moving bar in the entire frame to extract, analyze and identify the characteristic image information, Identify the corruption and enter the system.
2.3 Selection of Endless Rolling Technology
The company has developed infinite roll welding type technology (EWR) that can be adapted to various steel grades. Theoretically speaking, continuous casting and continuous rolling can basically be realized for steels where continuous casting is not a problem. EWR has the flexibility to stop at any time, so the requirements for roll line and modification are relatively loose. The problem of insufficient distance from the reheating furnace to the roughing mill can be solved by using the heating furnace for expansion and reformation, moving and adjusting the discharge groove of the discharge roll. This problem is suitable for the retrofitting of old factories. Continuous casting and continuous rolling technologies are more suitable for new production lines, especially for current capacity replacement and relocation projects, and priority should be given to production lines for short process bars. Endless rolling increases production capacity and enables companies to realize immediate economic benefits, saving energy and reducing emissions.
2.4 Intelligent selection of equipment for controlled rolling and controlled cooling
In the production of bearing steels, spring steels, unhardened and hardened steels, gear steels, engineering steels and other special types of steels that require controlled rolling and cooling, the use of thermomechanically controlled rolling and cooling can reduce off-line heat treatment of certain products craft. Controls grain size uniformity at the surface and core and improves overall length uniformity.
For example, rolling uses controlled rolling and cooling technology controlled by thermometers, infrared detectors and computer control systems to suppress high-temperature phase transformation and purify the structure, increasing the strength and ductility of steel. After direct rolling in existing processes, residual heat treatment can be achieved by rapid cooling. Take steel bars as an example: after intermediate rolling, the surface temperature of the rolled piece is 1000 ℃ ~ 1050 ℃, the temperature of the steel is cooled by a water cooling device, and then the final rolling and continuous rolling are carried out. After unit rolling, the surface temperature of the rolled piece will increase by 30°C to 60°C, reaching a range of 950°C to 1050°C. The rolled piece is then cooled by a water-cooling device to rapidly cool its surface. After the air-cooling phase, heat is transferred from the core of the rolled piece to the surface. Once the cooler turns red, the final cooling temperature of the rolled piece is about 600℃～750℃, which can improve the properties of the steel to achieve the purpose of organizational performance.
2.5 Selecting an online diameter measurement instrument
The use of online detection technology can improve the detection rate, solve the leak detection problem, reduce the detection rate, and bring potential safety hazards when manual sampling, which is very useful for improving product precision control. In-line detectors can be installed directly on the production line, using measurement technology to allow real-time detection and roll feedback and better direct process adjustments.
2.6 Add automation equipment to the checklist
Select an automatic counting device. Automatic rebar counters are generally suitable for products larger than 8 mm. Automatic counting and connection of steel bars can be done. Features include: high system reliability, robust interference protection including high-resolution images, and a complete counting process. The counting process can be automatically tracked by the data signal recording system. The main realization method of the technical function of the steel bar is through armature counting and segmentation. The system mainly uses visual technology to identify and locate the steel bar, then synthesizes the image, and finally completes the counting of the steel bar. Then, when there are a certain number of steel bars, software can be used to distinguish them, and then the steel bars can be automatically divided. It realizes normal counting and reduces the error rate to less than 1/10,000, which is well-received by users.
Choose from machines for weighing and binding rebar as well as systems for OEM and welding robots. The automatic rebar strapping system shall complete the collection of rebar from the inspection table into the strapping and transport it to the belt position using a roller conveyor. After the steel bars are first connected into a cylindrical shape, they are connected by a number of automatic control lines connected in series. The baler completes the full-length binding of the steel bars and transfers the cylindrical tendons through the roller table to the weighing area for re-checking and transfer to the work area for finished goods in stock. At present, most strapping machines use wires to complete automatic connection and automatic weighing, but label welding is still mostly manual. There are also steel belt balers that inject information about the steel belt through an inkjet machine, and double barcode identification is easy to track. Gradually, more steel mills use automatic welding and OEM robots. Depending on the process characteristics of the weld label in the finished area, the pre-printed label is welded and pressed to the end of the bar or to the surface of the bar. Image recognition software drives industrial robots to replace manual tasks, realize data storage of production line control systems and measurement systems, complete the entire welding process and OEM automation, and achieve the purpose of intelligent inventory.
In summary, the bar production line has been adjusted from 20m per second to 50m per second, forming a new type of intelligent steel rolling control system, which has qualitatively improved the production quality and output of bars. But even so, there are still problems such as insufficient processing of the fine processing system, instability of auxiliary equipment and connection quality, etc., which need to be transformed according to local conditions.