Preparation method for tension-roller thermal-sprayed coating

[0016] The method for preparing the thermal spray coating of the tension roller of the present invention includes the following steps:

[0017] Step 1: Pre-treat the surface of the tension roller, heat it to remove residual oil stains and moisture on the surface, and perform sandblasting and texturing on the roller surface to achieve uniform surface roughness and no reflection;

[0018] Step two, thermal spraying treatment on the surface of the tension roller, the thermal spray coating powder material adopts one of WC-Co, WC-CoCr, WC-NiCr or WC-Ni, and the thermal spraying parameter is the oxygen flow rate of 850-950 liters /Min, kerosene flow rate is 0.28-0.35 liters/min, spraying distance is 300-500mm, powder supply speed is 50-100 g/min, and the coating thickness obtained is ≥0.2mm;

[0019] Step 3. Seal the surface coating of the tension roller, configure the epoxy resin and curing agent according to the mass ratio of 100:40, mix them evenly, apply directly with a brush or spray on the surface of the tension roller coating , After coating, leave it for 24 hours or dry it at 100-120℃ for 2-3h;

[0020] Step 4. Polish the coating surface of the tension roller, and polish the surface coating roughness of the tension roller coating to Ra0.5-1.5 by using stone or diamond belt;

[0021] Step 5: Texture the surface of the tension roller coating. According to the required roughness of the final tension roller, use sand grains of different particle sizes to texture the surface of the tension roller to obtain different roughnesses of the tension roller coating surface. The blasting pressure of the texturing treatment is 0.45-0.55MPa, and the blasting distance is 300-500mm. For roughness Ra2-3, 80# sand can be used; for roughness Ra3-4, 60# sand can be used, for roughness Ra4-5, 46# sand can be used, roughness Ra5-7 can be used, 36 #沙粒.

[0022] Further, the above-mentioned epoxy resin is diethylene glycol ether bisphenol A type epoxy resin, and the curing agent is polyglycol ether diamine.

[0023] Further, the aforementioned sand grains are brown corundum sand grains or white corundum sand grains.

[0024] This method firstly sprays a thermal spraying layer with a certain thickness on the surface of the tension roller, so that the surface of the tension roller has excellent wear resistance. Secondly, the surface coating of the tension roller is sealed, and the sealant penetrates into the internal pores of the coating. The coating forms a good combination, so that the coating will not peel off in the subsequent sandblasting and polishing treatment; polish the surface of the tension roller to Ra0.5-1.5 again to remove the peak morphology of the coating surface after spraying; Finally, the surface of the tension roller is sandblasted and textured to the required roughness requirements to form a new surface morphology. Compared with the original sprayed surface morphology, the new surface morphology has reduced the height difference of the wave peaks, and the sharp corners of the wave peaks are more rounded, but the roughness meets the requirements of the tension roller design.

[0025] If the pressure of the strip steel and the tension roller is P, the contact point per unit area is n. If the peak height difference is reduced, the distance between the peaks becomes more uniform, and the abrupt sharp points decrease, then the contact point per unit area n becomes larger, and then it is dispersed to The pressure P/n of each contact point becomes smaller, so the friction between the surface of the tension roller and the steel strip is reduced, and the adhesion is reduced. The sharp corners of the wave crests are more rounded and will also reduce surface scratches. The tension roller prepared by this method not only maintains the wear resistance characteristics of the original thermal spray coating, but also has a new surface morphology and is more resistant to foreign matter adhesion, so that the roughness retention is better, and the tape caused by foreign matter adhesion is reduced. Surface defects of steel. Moreover, the process operation and production using this method are very simple, and the process controllability is very good.

[0026] Hang the sample pieces on the edge of the tension roller, one of them is taken off directly after the thermal spray coating is finished (comparative case), and the other is taken off after processing according to this method (implementation case). Microhardness test, falling ball impact test (5g steel ball, 500 balls each time, 3m stroke), surface roughness Ra and other performance inspection tests; the comparison results are shown in the table below, and the surface appearance is as follows figure 1 with figure 2.

[0027] Serial number Case Coating hardness Impact resistance Ra Surface topography 1 Comparative case samples HV1000~1200 ≥20 3.5~4.5 difference 2 Implementation case sample HV1000~1200 ≥20 3.5~4.5 it is good

[0028] Judging from the evaluation results of the implementation case and the comparative case, the microhardness, impact performance and Ra value of the sample prepared by this method are equivalent to that of the pure thermal spray coating; but the Ra value is equivalent, from the surface morphology of the coating, The surface morphology of the sample using this method is obviously better than that of a pure thermal spray coating. From figure 1 with figure 2 It can be clearly seen that although the Ra values ​​of the two samples are basically the same, the coating morphology of the implementation case is relatively uniform, the peaks and valleys are alternately distributed, and the amplitude is relatively uniform, the peak height difference is small, and the spacing is uniform. From the surface morphology, when the strip 1 is in contact with the sample surface 2, then figure 1 Contact point of the comparison case in n 1 About 8, and figure 2 Contact point of the implementation case n 2 It is about 27; when the pressure P between the strip steel and the sample is fixed, it is obvious that the pressure applied to each contact point in the implementation case is much smaller than that in the comparison case. Therefore, when the surface coating of the tension roller is prepared by this method, the contact between the surface and the strip steel is more uniform, the surface scratches are reduced, the adhesion is reduced, and the thermal spray coating can effectively maintain the inherent good wear resistance properties of the thermal spray coating. In addition, the method can conveniently and effectively obtain various required roughness requirements.