# Design description of welding equipment for investment casting process group of impeller blade

(1) The welder assembly of impeller blade assembly is composed of 6 parts: upper cover plate, lower cover plate, locating ring, fastening shaft rod and 2 backing plates.

(2) The outer diameter and height of the locating ring are the key dimensions in the design of the assembly welding fixture. In the design process, the shrinkage of zg1cr18ni9ti and the shrinkage of wax mold should be considered. Since it is a composite mold, it can be considered that the size of the wax mold obtained after pressing should be approximately equal to the size of the sand mold pattern, that is, the outer diameter of the locating ring is equal to the original size multiplied by (1)+ ε）。 The height of the locating ring is equal to the original height plus the machining allowance below and multiplied by (1+ ε），ε Is the shrinkage rate of sand casting alloy, taken as 2.2%.

(3) Outer diameter of locating ring = 416 × （1+2.2%）=425.15±0.25mm

(4) Height of locating ring = (130 + 3 + 5) × （1+2.2%=141.04≈141mm

(5) Outer diameter dimension of upper cover plate = 700 (outer diameter of impeller) + 2 × 30 (thickness of formwork) + 80 = 840mm

(6) Outer diameter dimension of lower cover plate = 700 (outer diameter of impeller) + 2 × 30 (thickness of formwork) + 2 × 100 (thickness of sand jacket) + 2 × 100 (width of sand ferrule) + 80 = 1240mm

(7) In order to strengthen the strength of the mold shell and the positioning between the mold shell and the sand mold, a layer of sodium silicate sand sleeve is reinforced around the mold shell after the mold shell is coated. The positioning problem during formwork reinforcement shall be considered in the design, and the diameter on the lower cover plate is Φ 973mm step is the outer diameter of sodium silicate sand sleeve, and its size = impeller outer diameter + 2 × Shell thickness + 2 × Thickness of sand sleeve. The outer diameter of sodium silicate sand sleeve is Φ 973mm, and the thickness of sand sleeve is about 100mm.

(8) Effective length of fastening shaft = height of locating ring + thickness of upper and lower cover plates + 2 × The thickness of the base plate is + 80 ≈ 318mm, and its diameter is Φ 30mm, a M30 nut is welded on each fastening rod and connected with the fastening shaft through the nut.

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