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Life Analysis of Cast Iron Plate

2019/6/23 18:38:47 Viewers:
Measurement of Scraping Depth and Scraping Contact Spot Area and Life Analysis of Plate

The results of wear investigation on 20 plates are as follows: 2 Hebei Botou cast iron plates, one of which has been used for more than five years, are still in normal use; the other conductor has been used for more than five years, and the corrosion caused by poor storage has been repaired. The remaining 18 cast iron slabs scraped and polished by other provinces and municipalities have been used for one year. After verification, 10 of them are seriously worn out and need to be repaired. Eight of them can still be used, but some of them have been spotted and patched. The average scraping depth is 37.36 micron for No. 1 plate and 9.06 micron for No. 2 plate. The difference between them is more than three times. According to the relationship between friction curve loss and friction time, the plate is always in the initial wear stage, the curve is linear, and the wear amount is proportional to the friction time. As a result of the investigation of plate wear, the service life of Hebei Botou plate is five times as long as that of Wafangdian plate. Obviously, the influence of scraping depth on the service life of flat plate can not be ignored. JJG 117-91 plate verification regulation does not stipulate scraping depth, which is undoubtedly a defect. From the above test results, it can be seen that the contact spots are approximately the same, but the contact areas measured are 20% and 10%, respectively. The difference is very large. From the point of view of use, the service life of the flat plate can be improved by increasing the contact area as much as possible without causing the workpiece to lap into the flat plate. JJG 117-91 Plate Verification Regulation also does not appropriately restrict this item.

In order to improve the service life of the plate and ensure its working accuracy, it is suggested that the scraping depth should be controlled at or above 0.02 mm, so as to ensure a longer service life and verification period of the plate. According to the introduction of scraping depth and the measured data of scraping depth, the processing requirements of this process can be achieved. For the control of contact speckle area, the UK Standard Specification for Plate and Platform stipulates that the proportion of supporting area for AA (equivalent to JJG 117-91 specification 0), A (equivalent to JJG 117-91 specification 1) and B (equivalent to JG 117-91 specification 2) is not less than 20% and 10% respectively. Highlights should be evenly distributed, and the proportion of supporting area should not be high enough to cause adhesion of the workpiece. This regulation not only guarantees the accuracy of the plate, but also takes into account the service life of the plate, which can be used for reference.

Notice in cast iron plate casting: The control of casting grinding process and the properties of moulding sand will directly affect the quality of measuring tool castings. Therefore, moulding sand should have good permeability, wet strength, fluidity, plasticity and yielding. Strictly according to the order of feeding: old sand - new sand - clay - coal powder - water. The mixing time is set at 6-7 minutes, and the mixing time is about 5 hours. After leveling, sieving, loosening and reusing can make the moulding sand loose, so as to improve the permeability and fluidity. Control of casting process. The casting water should be inoculated and slag removed before pouring. In the process of pouring, it is necessary to flow continuously and smoothly so as to avoid sand scouring and formation of sand holes. In order to reduce the defects of cold insulation and insufficient pouring, it is necessary to plug the part of lost casting water and make up for the casting water in time when running out of fire. The control of casting cleaning process is that the measuring tool castings are cleaned from the casting mould after cooling in order to obtain the surface defect-free measuring tool castings.

Reasonable process: Operators should operate strictly according to the process. Calculating the structure of the measuring tool castings can make the pattern manufacturing simple and convenient, make the number of parting surfaces less, have the inclination of drawing die, the number of sand cores less, have reasonable wall thickness, and have transition at the joint. Reasonable gating system is selected to solidify the measuring tool castings sequentially so as to obtain the measuring tool castings with uniform structure.

Closing the box: Closing the box is an important link that can not be ignored. The floating sand on the surface of the casting mould should be cleaned up, combined according to the seal, and pay attention to the wrong box quantity. It is an important means to reduce the bias box of measuring tools and castings.

Core setting: When core setting, it should be smooth and clear floating sand. The position of sand core should be well placed to prevent the deviation of core. Drying: For the drying process of the dry mould, the operation should be carried out according to the operating rules. The drying time is more than 8 hours, in order to prevent sand, stomata and other defects caused by the impermeability of drying. Attention should be paid to the EPC coating of cast iron slab.

(1): Coatings requirements: use water-based graphite paint, its Baume of 60-70, painting in the greenhouse, before drying, strictly prohibit removal, in order to prevent deformation.

(2) Brushing requirements: uniform mixing of paint, strict whiteness when brushing.

(3) Coating drying: Coatings should have enough strength after drying, drying for 24 hours at 50-60 C.