a. Gas cutting process parameters
The gas cutting equipment of impeller investment casting sand casting pouring and riser adopts g01-300 cutting torch gas cutting (No. 4 annular cutting nozzle), oxygen cylinder and acetylene cylinder. See table for process parameters.
| Amplitude H / mm | Swing frequency / (times / min) | Preheating temperature | Flame properties | Cutting oxygen pressure / MPa | Acetylene pressure / MPa |
| 10-15 | About 80 | Preheat to surface melting | Neutral flame | 0.8-1 | 0.05-0.1 |
b. Operation process and Essentials
(1) After the water glass sand mold and sand sleeve are cleaned, g01-300 cutting torch is used for gas cutting. The preheating flame is larger and more concentrated than the general carbon steel cutting flame. Neutral flame is used. The oxygen pressure needs to be increased by 15% ~ 20% to 1MPa. If necessary, another cutting torch can be added for preheating.
(2) During gas cutting, heat from the edge of the cutting part first. When it is in the molten state, open the cutting oxygen valve and raise the cutting torch a little, then the slag can flow out of the incision. At this time, the cutting torch swings back and forth and up and down to a certain extent. The vibrating cutting oxygen flow breaks through the high melting point chromium oxide produced at the incision, so that the iron continues to burn, and the slag can be washed away through the up and down, front and back impact grinding of the oxygen flow, so as to realize continuous cutting.
(3) The amplitude h of vibration gas cutting is 10mm ~ 15mm, and the amplitude before and after vibration gas cutting should be larger. The frequency is about 80 times per minute. Maintain a certain caster angle of the nozzle during cutting.
(4) The vibration gas cutting process is adopted for the pouring and riser of impeller investment casting sand casting, which has the advantages of simple equipment, easy to master, and large cutting thickness. When plasma arc cutting conditions are not available or plasma arc cutting is inconvenient, vibration cutting has its practicability. It can cut stainless steel plates with a thickness of more than 300mm.
Using this process, the minimum cutting residual length of the pouring riser of impeller investment casting sand casting can reach 10mm. Although the notch is not smooth enough and the precision is low, it can fully meet the requirements of impeller investment casting sand casting. When cutting, one worker can cut three impellers in investment casting sand casting system in only 4h, consuming one bottle of acetylene and two bottles of oxygen, which saves labor and time and reduces the cost.