The drive wheel is an important part of a large crawler agricultural tractor. The material grade of nodular cast iron is GGG60-DIN1693. See the table for the mechanical properties of the material. The overall dimensions are ϕ 916 mm × 526 mm, 260 kg mass,structure, 19 teeth evenly distributed along the circumference, and the root of the teeth are isolated hot spots; Since the track is placed between the two teeth, the tooth is not allowed to have a mold angle; The internal quality of castings is required to be level 2 for radiographic inspection, and the anatomical verification standard is 38.1 mm × The range of 38.1mm is allowed to be less than ϕ 12.7 mm shrinkage. The surface quality is required to be 38.1mm × Within the range of 38.1 mm, no more than 2 mm in diameter and no more than 5 pores are allowed. The parts are as shown in the figure.
|Performance||Tensile strength/MPa||Yield strength/MPa||Elongation (%)||Hardness (HBW)|
|Standard requirements||≥ 600||≥ 370||≥ 3%||187~269|
(1) The use of core assembly design can eliminate the angle of mold lifting in specific areas, and the seam of ductile iron castings is small.
(2) Multiple isolated hot spots use riser technology to effectively solve the defects of shrinkage porosity and shrinkage cavity in ductile iron castings, and the use of cold iron at the place far away from the riser to reduce the hot spot can effectively extend the feeding distance of the riser.
(3) The drying process of coated sand core can effectively reduce the gas generation of sand core and reduce the porosity defect.