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Process of rolling mill side brick groove casted by LFC

Jun. 11, 2019

I. Product Overview

The brick groove on the side of the machine has an outer contour length of 1100mm, a width of 580mm, a height of 360mm and a minimum wall thickness of 20mm. The internal space is large and it is easy to deform. In the early stage, the sand mold casting process is adopted. In the production process, the the process of core setting and box closing is tedious. The casting defects like flash and burr may appear easily, and the surface quality of the product is not good. LFC process can greatly reduces the process of core setting box closing, etc., which greatly improves the surface quality of the product.


II. White Area

The structure of the white model needed to produce the brick groove on site is relatively simple and the size is relatively diverse, so the method of cutting and gluing the white model is adopted to form. During gluing, the gluing of the pouring gate and hot melt glue, there can’t be lacune at the gluing place, preventing the painting into the lacune and the defects of slag inclusion after pouring.

Because the size of the sand box is 1400mm*1200mm*1200mm, horizontal single pouring is adopted. The sprue is 40mm*40mm. The runner is 40mm*40mm. The runner gate is 40mm*20mm. Micro venting and slag accretion riser is set at the top of the casting. The support is added between the wings to prevent casting deformation. The gating system is spliced after the third time of coating.

Process of rolling mill side brick groove casted by LFC

III. Yellow Area

1. When brush the coating for the first time, the paint and water are mixed in a ratio of 1:0.6. Pour the measured water into the blender bucket and start the blender. With the blender under working condition, pour the coating in slowly(with the whole bag in) and stir for more than 2 hours. Stir well without hard lumps. Measure the coating density(baume degree 60-65). After qualified, pour the coating into the brushing slot. Let it sit for 5 minutes and then that can be used. Brush the coating for the first time, don’t make the coating too thick to avoid surface cracking when drying, which affects the casting quality. Because the casting size is large, adopt brushing method.

Put the coated model into the drying room after grouped and uniformly brushed. The space between two models is more than 150mm. The drying room adopts electric heating method. The temperature in the drying room is controlled at about 45℃. The temperature needs not to be too high, or there maybe cracks at the corner angle. The humidity is lower than 15%. The coated model should not be blown directly by the drying heater, or there maybe cracks at the corner angle because of too high heat. Under the environment of this condition, dry for about 8 hours and the coating thickness is 0.4—0.6mm.

Process of rolling mill side brick groove casted by LFC

2. When brush the coating for the second time, the density is high than that for the first time(baume degree 68-70).Brush the dried model according to the way brush for the first time. The coating thickness is 1.0-1.5mm after dried. After that, move the model to the drying room, keeping separated from the models that are painted for the first time. The drying time for the second time is 12 hours.

Process of rolling mill side brick groove casted by LFC

3. Brush for the third time according to the brush way for the second time. After the three times, the model is coated evenly with no lack of painting, no flowing or no air bubbles. The drying time must be more than 24 hours.

Process of rolling mill side brick groove casted by LFC

IV. Black Area

1. Filling sand and moulding:

Use 30-40 mesh ceramsite. The thickness of the bottom sand is 300mm. Vibrate the sand for 50-60 seconds and then put the model at a 15° degree. With the pouring gate slightly upward, vibrate for the second time for 30-40 seconds for full vibration. The vibration time doesn’t need to be long to avoid model cracks. After the second vibration, fill sand to the top surface of the pouring pouring cup and then vibrate for the third time. Then cover with plastic film and add sand. To avoid the melt iron from flushing the sand around the pouring cup into the casting when pouring, apply alcohol coating around the sprue.

Process of rolling mill side brick groove casted by LFC

2. Pouring

The tapping temperature is controlled from 1500℃ to 1530℃. The pouring temperature is from 1390℃ to 1420℃. The negative pressure is -0.05MP. The pouring speed is 8-10 kg/s. The negative pressure of -0.02MP is maintained for 7 minutes. Keep heat for 3 hours and then turn over the box. Clean the casting after shot blasting.