Causes and countermeasures of Indian iron stent injury (2)

1. The steel used for the bracket is hard and does not deform at high temperatures of 220°C;
2. In the manufacture of brackets, it is required that the brackets should not be flat and that they cannot be deformed. When they are loaded with large chains, they cannot be deformed, distorted, and remain flat.
3. The surface requirements are smooth and can not be rough.
In actual use, the bracket of the LTG oven in Germany is more ideal and can generally meet the above quality requirements. Therefore, in the normal production process, as long as the operation and adjustment is reasonable, the occurrence of stent injury can be avoided. The domestic-made brackets such as Nantong drying room equipment, regardless of material quality or processing and manufacturing quality, have a certain gap compared with the advanced German LTG brackets. There are mainly poor materials, which are easily deformed under high temperature. The flatness of the stent is poor in processing and manufacturing, and it is easily deformed when mounted on large chains. In addition, there is a large gap between the surface finish and the LTG oven. This shows that the low quality of the stent itself is another important cause of stent injury. 
Third, other relevant factors
1. Influence of the recirculating wind system
Adjustment should be appropriate. Improper adjustment, excessive air volume, and excessive wind speed will cause the brackets with tinplate prints to vibrate, resulting in stent injuries. Especially in the constant temperature zone of the oven, the air volume at the air nozzle and the air return port is too large, which easily causes the bracket to shake and cause the occurrence of the bracket injury. When the thickness of tinplate stampings is between 0.15 and 0.20mm, the hot zone requires the reduction of the hot air circulation, and the requirements cannot be reduced. The oven manufacturer is specially designed to avoid scratches and other ills. 
2. The influence of tinplate
Tinplate is composed of steel base, tin plating, tin-iron metal, oxide film and oil film. Under normal circumstances, the phenomenon of melting of tin will not occur below 230°C. However, in the actual construction, due to uneven oven temperature, table temperature and furnace temperature and other reasons, it is also easy to produce stent injury. It has also been found in the production practice that tinplates of the same specifications have different severity due to different origins, and may be due to the different materials and processing techniques of the tin layer of the steel base. 
3. Effect of paint
Pig iron coating according to the use of different external coating and internal coating, external coating is color printing before and after the coating process, also includes non-printing of the outer wall coating. There are mainly primers, white paints, ink paints, transparent paints, etc. The inner paint is the inner wall paint after the product is formed, which has anti-corrosion effect on the contents, and at the same time has rust prevention and protection. The above coating mainly consists of a vinyl resin, a polyester resin, an acrylic resin, an epoxy novolac resin, and the like. Due to the different paint manufacturers, the quality is uneven. Take the food coating epoxy phenolic resin as an example. There are hundreds of manufacturers in the country. When choosing a product, we must do a lot of test work and select excellent quality products. In general, the better the adhesion, the higher the hardness of the surface after curing of the coating film, and the smaller the possibility of a stent injury, and vice versa. 
4. Others
Many printing iron manufacturers may also be using older ovens, which use long shaft drives. There are more than 20 bearings on the long axis. The wear of the bearings leads to unstable rotation of the long axis and affects the stability of the support. Therefore, it is very important to perform regular maintenance on the bearings. Many manufacturers' ovens have been changed to variable frequency synchronous drives, which is beneficial to the stability of the support. In addition, various manufacturers have taken effective measures to reduce or avoid stent injuries. Specific practices include:
1 Wrap the heat-resistant and wear-resistant rubber ring on the bracket to reduce the contact point between the bracket and the tinplate;
2 Use epoxy phenolic coatings with high hardness and wear resistance as much as possible (manufactured by different manufacturers, the quality gap is very large);
3 When the bracket is selected, high-quality steel or stainless steel material is used so that the bracket does not deform at high temperatures. In addition, in the reasonable arrangement of the construction process, in the installation of guide rails and large chains, the selection of graphite rollers has also taken a lot of brains.