Quality improvement method for edge clearing defec

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Quality improvement methods for edge cleaning defects of float glass

various quality defects of float glass in the process of edge cleaning have always been a long-standing problem perplexing various float glass companies. Many appearance quality can no longer meet the growing quality needs of customers. At the same time, they will also receive quality complaints caused by edge cleaning defects, which has seriously affected the company's product image and brand image in the eyes of customers. Therefore, float glass companies should improve and improve the quality of edge cleaning, which can not only enhance the brand value of products, meet customer needs, but also reduce the workload of labor

(I) improvement of edge cleaning defects with conventional thickness (8mm~12mm)

1 Quality defects of conventional glass edge cleaning in a production line at present, the structure of automatic edge cleaning machine in the cold end production lines of major float glass companies in China is similar, and the mechanical principle is basically the same as the mechanical device. Therefore, the same problem generally exists. Due to the uneven stress distribution of glass during annealing, local deformation defects such as concave convex edges are caused at the edge cleaning part during the production of conventional glass. Small deformation customers have no impact without affecting the secondary cutting, but with the increase of glass thickness, this defect will become more and more obvious, and some customers' cutting ability is not high, so they cannot meet customer requirements

2. Improvement principle

there are two ways of thermal stress in glass, temporary stress and permanent stress. In the process of glass changing from hot to cold, when the glass completely reaches the room temperature of the microscope that inspects the surface (metallographic structure) of the metal sample with the incident light, in order to eliminate the internal temperature gradient and make the glass reach equilibrium, one part of the glass deforms and the other part forms the permanent stress of the glass. Where the temperature is high, the expansion is large, and where the temperature is relatively low, the expansion is small. In this way, the glass with lower temperature gives a compressive stress to the glass with higher temperature to prevent the expansion of the glass with higher temperature, while the glass with higher temperature gives an outward tension to the glass with lower temperature for expansion. We call this tension greatly improves the stability of the product, which is the tensile stress of the glass. In this state, the stress in the glass due to the temperature gradient will naturally disappear when the temperature of the glass plate reaches equilibrium. We call this kind of stress temporary stress. Cutting is to make full use of the characteristics of this temporary stress of glass for cutting

3. Improvement measures

after long-term observation and research, there are many reasons for defects. Under the normal condition of annealing at the hot end, due to the excessive impact of the upper pressing wheel when pressing down, the lower edge cleaning roller table is relatively hard, and the stress is not well released when the edge is separated along the cutting scar, resulting in the deformation of the glass, and the concave and convex defects will appear after on-site observation. For the reasons: first, change the point pressing mode of the upper pressing wheel to linear contact and overall pressing, and change the material from the original cast iron to nylon or hard rubber; Second, change the hardness of the roller table at the edge cleaning pressing wheel from the original iron to the outer hard rubber roller for the edge cleaning roller table

(II) edge cleaning quality improvement of ultra thick glass (15mm~19mm)

1 Cutting principle of glass plate

the micro cracks on the surface of glass will seriously affect the mechanical strength of glass. When the crack depth is 0.001mm, the strength of glass will be reduced to 1/100 of the original strength. The cutting scratches of glass make effective use of this feature. Because the thicker glass is easy to form uneven stress in the annealing process, and extremely small glass chips will be embedded in the very small cut, coupled with the removal of the compressive stress at the edge, the originally caused crack will not crack vertically according to the ideal state, resulting in the difficulty of clearing the edge of thick glass. Therefore, the thicker the glass, the more difficult it will be to clean and cut

2. At present, when a production line produces ultra thick glass (19mm), 90% of the automatic edge cleaning will cause quality defects such as multiple missing corners and concave convex edges, which seriously do not meet the quality standards and customer needs, so almost all of them use manual edge cleaning. In a production line 6002, according to the type of stress cycle, it can be divided into: constant amplitude fatigue test, frequency conversion fatigue test, program fatigue test, random fatigue test, etc; On the ton cold end production line, the prototype of the thick plate edge cleaning mechanism is improved, and the edge cleaning of ultra thick glass is effectively solved by using the method of edge rolling

3. Working principle of the edging mechanism

the lower roller adopts a nylon roller (diameter 100mm, length 100mm) with a slightly inclined cylinder, and the upper roller adopts a slightly elastic hard rubber roller (diameter 120mm, thickness 20mm). When the horizontally broken glass comes directly below the edging mechanism, the lower roller first lifts 2~5mm higher than the roller table, and at this time, the upper roller presses down, so as to just touch the upper surface of the glass, At this time, there are 9 impact tests on both sides of the cut mark, an upward jacking force and a downward pressure. In the good state of the knife mark, under the action of such a small bending force, the glass edges will be separated orderly along the knife mark, realizing high-quality edge cleaning effect

improvement effect and revenue

after the improvement, the edge quality of conventional thickness has been significantly improved, which can achieve the same section uniformity as horizontal breaking, and can meet the cutting needs of senior customers. After a series of successful transformations of the edge cleaning mechanism and the determination of the reasonable values of various process parameters, the defects caused by edge cleaning have been eliminated in the production of conventional thickness glass, ensuring the smooth quality of the edge, Fully meet the needs of downstream customers of various processing types. The complaint rate of ultra thick glass has been reduced by 90% on the basis of one edge quality complaint per month. The total investment cost of the transformation is no more than 3000 yuan (because it is the transformation of the original equipment of a production line, excluding the cost of inherent equipment such as steel structure and cylinders). After the transformation is successful, about 140 tons of qualified products are promoted for the company every year, with a total income of about 203000 yuan and a reduction of complaint compensation of about million yuan

with the improvement of the quality of domestic customers' products, their requirements for the quality of float glass are higher and higher, and they also put forward higher requirements for the cutting quality of float glass. I only hope that this article can provide some references for the same industry in the cutting of float glass

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