Wuxi Dongao Nonferrous Casting Co., Ltd.
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Elimination Of Large - Scale Valve Casting Shrinkage And Porosity Method
- May 26, 2017 -

In the production of large-scale valve castings, often encountered shrinkage, pores and other defects, welding volume and grinding volume is quite large, and the surface is not beautiful, and some found in the hole hole, test water when there is leakage Phenomenon and scrapped. Here are some solutions.

1, to switch to the local real water glass and curing agent, both local materials, reduce costs, but also improve the performance of sand, improve the quality of the mold to reduce the root causes of various defects.

2, to improve the design of the Valve Castings process, the original process of pouring system using refractory tee, molten steel in the bottom of the middle of the convergence of convergence, resulting in sand, coupled with exhaust flow, resulting in stomata, due to water glass sand cooling speed, So slag, sand, gas can not float to the riser, resulting in surface defects and more.

3, due to the box is not high, riser height does not meet the requirements, dedicated to pouring on the riser, hinder the exhaust, and cause slag, sand, gas reflux phenomenon, is also one of the root causes of defects, Improve the riser height and capacity, reduce the amount of molten steel is also corresponding to reduce the sand, slag, gas reflow caused by the phenomenon of defects.

4, to change the riser cover the species, the original use of the cover agent, although added to the riser can also heat insulation, but soon crust, not only affect the effect of filling, but also seriously affect the exhaust and slag, Homemade cover agent, both cheap and good.

5, pouring system changes. ① the original from the flange at both ends of the three-way refractory pipe casting method, switch to a small flange from one end with four pouring into the molten steel, so that cavity exhaust, slagging, row of sand to the riser, Smooth. ② increase the area of direct pouring, from the original qb50mm refractory tube to qb70mm refractory tube, increase the flow and improve the casting speed. ③ to cancel the original two ends connected to the fire pipe of the two large riser, switch to a small flange on the two open risers, easy to exhaust and fill, but also to improve the hot section is uneven, unfavorable sequence of cooling Claim. ④ often caused by iron sand, water glass chrome ore, eliminating the iron sand sand defects.

6, in strict accordance with the process requirements to control the temperature, pour the speed, the riser filled, and then fill the riser.

7, riser addition to height, increase the slope but also the use of heat insulation riser, not only save the molten steel, improve the riser effect, but also to prevent the water glass sand cooling speed, affecting the effect of contraction, to prevent The riser root and the Valve Castings are connected at the junction.