Trial production process As the roll requirements of ultra-probe detection and high and low test, to ensure that the trial to achieve the desired purpose, so that a successful trial roll. After repeated research, the following production process: electric furnace smelting ladle blowing argon pouring hot forging forging afterging heat treatment roughing inspection final heat treatment finishing.
Casting casting with 950mm roll casting casting semi-steel blank, electric heating riser, slab for the shaft shape, can improve the utilization of slab. After the hot out of the box, the preheating treatment (process such as rough) hot feed to the forging plant, slab normal. The actual production of ingredients.
Forging forging heating process such as forging before the use of low temperature for a long time heating diffusion, conducive to the composition of the homogenization. As the slab for the roll shape, the use of direct drawing process, forging ratio of not less than 2 <7>, a slab out of a blank, Impact bonding cookware press can improve the utilization of slab. Forging for the use of the flat, the next V-anvil forging (the anvil the older the better), effectively reduce the tensile stress and increase the compressive stress, to avoid the forging crack generation; should try to choose a small pressure reduction (80mm), cracks Timely clean up, fire generally should be two fire to complete. Final forging temperature of 900, forging air cooled to 450500 into the furnace heat treatment.
The forging heat treatment of the forged forged semi-steel roll is mainly to eliminate the residual stress during the forging process and to homogenize the structure so that the carbide is uniformly and finely precipitated from the austenite, and the grains are refined to obtain small particles Uniform spherical pearlite, and prepare for subsequent finishing. Forging heat treatment According to the normalizing + spheroidizing + hydrogenation annealing (such as), forging heat treatment of the microstructure (photos such as): nodular pearlite ten carbides, hardness of 220240HB, with good processing performance, see , For the follow-up heat treatment to do a good job of preparation. 1, 2, after the billet forging after stripping 2 qualified, 1 riser end journal failed, the analysis that the pressure control is not accurate enough, the actual forging when the spindle out of the roll there are surplus surplus material production roll Neck, resulting in excessive deformation of the roll neck.
According to the high and low times the report shows that from the edge of 90130mm there are two about 3mm crack, the central part of a number of cracks, the longest 4mm, slab residual shrinkage more, resulting in waste. Followed by the production of the third test qualified. The final heat treatment of the final heat treatment is to meet the roll hardness, organization, performance requirements, in order to achieve the use of wear resistance, anti-accident and other requirements.
Curve such as. After the final heat treatment, the roll body is fine pearlite + secondary carbide (photo such as). The factory hardness of 3842HS. After the final heat treatment of the various parts of the mechanical properties of the roll as shown in Table 4. Casting semi-steel 140CrNiMo tensile strength is generally 500700MPa. Can be seen from the table, the tensile strength of more than 800MPa, Pull strength has greatly improved, and much larger than the product requirements of 500MPa, to meet the product requirements.
Conclusion (1) the use of slab for the roll shape directly pull the long process, forging ratio of not less than 2, forging out the qualified forging semi-steel roll blank. (2) forging when used on the flat, under the V-anvil forging (the anvil the older the better), effectively reducing the tensile stress and increase the compressive stress, to avoid the forging crack generation. (3) Although there is a product after forging waste, after the skilled operation, strictly control the amount of reduction, to the detection requirements. (4) the final organization and performance of the product to meet user requirements, and to achieve a higher performance.
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