China Machine Tool Industry Association Quality Bulletin
Plate rolling is a process of continuous three-point bending of sheet metal using a plate rolling machine. The equipment puts the sheet material between the upper and lower work rolls when rolling. The upper roller is raised and lowered vertically, and the two lower rollers rotate and move horizontally relative to the axis of the upper roller. When the upper roll descends, the plate is plastically deformed and bent between the upper and lower work rolls. The continuous rotation of the bottom roller drives the steel plate to advance and retreat through the friction between the plate and the roller to complete the coiling. Rolling Machine,Three-Roller Bending Machine,Four-Roller Bending Machine,Roll Forming Machine Rugao Yaou Import & Export Trade Co., Ltd , https://www.ntyaous.com
1. Milling bed, drilling machine product quality national supervision and spot check results This time, 38 kinds of 38 enterprises produced in Liaoning, Jilin, Heilongjiang, Shanghai, Jiangsu, Zhejiang, Anhui, Fujian, Jiangxi, Shandong and Guangxi, 11 provinces, autonomous regions and municipalities directly under the Central Government Milling and drilling machine products were supervised and spot-checked. The spot check is based on GB15760-2004 "General Technical Requirements for Safety of Metal Cutting Machine Tools" and GB5226.1-2002 "Mechanical Safety Mechanical Electrical Equipment Part 1: General Technical Conditions" and other standards, leakage and geometric accuracy of milling machine and drilling machine products. , winding and entangling hazard, limit device, mechanical overload protection, anti-loose device, interlock device, clamping device, guard device, start, stop, emergency stop, noise, splash, motion reliability, power switch, protective ground 22 safety and important performance items such as insulation test, circuit overcurrent protection, motor overload protection, electric shock protection and control transformer were tested. Seven products were unqualified in the spot check, and the main quality problems were:
1 There are 4 kinds of products whose geometric accuracy is unqualified, which will affect the processing performance of the machine tool. 2 There are 2 kinds of products that are entangled and involved in dangerous items. In some products, the handwheel of the longitudinal feed axis does not adopt the automatic disengagement device when maneuvering, and the handwheels at both ends are in high-speed rotation state, which is prone to danger; some longitudinal radial arm drilling products are not closed in the longitudinal transmission shaft. There is a risk of entanglement during work. 3 There is one type of product that is not covered by electric shock protection. The dangerous voltage metal terminal in the electric cabinet is bare, and there is no protective partition and electric shock warning sign. 4 There is a product emergency stop device that does not meet the safety requirements, the mushroom button does not have self-locking and manual unlocking functions. 5 If there is a product whose power switch is unqualified, the switch does not lock the mechanism in the disconnected position, and it is prone to illegal operation. 6 There are 2 kinds of products to control the transformer failure, mainly for the transformer does not provide appropriate protection.
2. National Supervision and Inspection Results of Grinding Wheel Product Quality This year, we conducted supervision and spot checks on 200 kinds of grinding wheel products produced by 197 enterprises in 11 provinces including Hebei, Liaoning, Jiangsu, Zhejiang, Anhui, Fujian, Jiangxi, Shandong, Henan, Hubei and Guangdong. . The spot check is based on the mandatory national standard GB2494-2003 "General Abrasives Safety Rules", the recommended national standard GB/T2485-2008 "Consolidated Abrasives Technical Conditions" and the industry standard JB/T6353-2006 "Consolidated Abrasives and Rubber sheet grinding wheel, JB/T3715-2006 "Consolidation grinding wheel grinding wheel", JB4175-2006 "Consolidated abrasive fiber reinforced resin cutting wheel" and other standards, appearance defects, dimensions of the grinding wheel product, Seven items including shape and position tolerance, hardness, static imbalance, swing test and sign were tested. In the spot check, 30 products were found to be unqualified, and the main quality problems existed:
1 The fixed abrasive fiber reinforced resin cutting wheel rotating project produced by a factory was unqualified. The 10 pieces of fiber reinforced resin cutting wheel that were inspected all showed turning and breaking when the requirements of the inspection speed were not met, which was a serious quality problem. 2 There are 17 types of grinding wheel for grinding, fiber reinforced resin cutting wheel, ceramic flat grinding wheel and resin flat grinding wheel. Large or small diameters of the grinding wheel can cause the grinding wheel to rupture during use. 3 There are 4 kinds of ceramic flat grinding wheel products with unqualified hardness.
Second, the quality of enterprise products must be strictly managed. Not long ago, the Minister of Industry and Information Technology Li Yizhong said at the 16th China Quality Forum: "Strengthening product quality is an important measure to promote industrial economic development. The Party Central Committee and the State Council attached great importance to product quality work. On November 11, last year, General Secretary Hu Jintao made a lengthy remark on the quality issue, emphasizing that strengthening product quality is not only to meet the current needs of the international financial crisis, but also to adjust the industrial structure and transform the development mode. To improve China's international competitiveness, a long-term strategic task must conscientiously implement relevant laws and regulations, persevere, strict management, and constantly unremitting."
Although the state's supervision and inspection results on the product quality of the machine tool industry only check the quality problems of some enterprise products, it also reflects from one aspect that although the overall quality level of the industry is constantly improving, there are still many product quality problems, and some even There are serious quality problems with the product. Therefore, we must enhance the quality awareness, strengthen the main responsibility of the enterprise, and profoundly understand that quality is the life and reputation of the enterprise, and it is the concentrated expression of market competitiveness.
The quality construction of an enterprise should focus on the quality of the varieties, and establish a full-person, whole-process, all-round quality management system and quality credit system. In order to grasp the development of varieties, we should do a good job in market segmentation, find the right position, and produce products that meet market demand and marketability. To improve the quality of products, it is necessary to improve the safety, reliability and practicability of products by improving the physical quality of products. To grasp the brand building, we must strive to create high-quality brands and brand-name products, and enhance the social recognition of the brand. To improve service, we must be responsible to the users, and do a good job in pre-sales, after-sales service and sincere performance.
As 2009 is about to pass, our machine tool industry enterprises should continue to implement the decision-making arrangements of the Party Central Committee and the State Council on improving product quality on the basis of earnestly summarizing the quality construction work of the past year, and focus on the production capacity and growth of the enterprise from the past. The rate has shifted to the quality, efficiency and sustainability of production growth, to optimize product structure, improve independent innovation capability and strengthen product quality construction, and upgrade the quality of industry products to a new level.
1. Pre-bending. When the plate is rolled, there is a length at both ends of the plate that does not bend because it does not touch the upper roller. It is called the remaining straight edge. In the process, the minimum force arm at which the plate starts to bend is called the theoretical remaining straight edge. The bending form (symmetrical bending, asymmetrical bending) is related.
2. Centering. The purpose of centering is to make the generatrix of the workpiece parallel to the roller axis to prevent skew.
3. Roll round. Rolling is the main process of product forming, which is divided into two types: one-time feed and multiple feeds. Multiple feeds are commonly used for rolling thick plates. The number of feeds depends on the technological constraints (such as the maximum allowable deformation during cold rolling) and equipment constraints (such as non-slip conditions and power conditions). When the rebound of the cold coil is significant, a certain amount of overcoiling must be added.
4. Straightening round. The purpose of rounding is to make the curvature of the entire circle as uniform as possible to ensure product quality. The general rounding process is divided into three steps:
(1) Load: According to experience or calculation, adjust the work roll to the position of the required maximum correction curvature.
(2) Rounding: Roll the roller 1 to 2 turns under the corrected curvature to make the entire curling rate uniform.
(3) Unloading: gradually unload the load, so that the workpiece is rolled several times under the gradually reduced correction load.