Gear pump wear parts how to repair?

(1) gear wear repair

The wear parts of the gear are mainly the meshing of the teeth, the involute face and the two ends of the gear. Slight wear, the tooth surface can be whetstone grinding, both ends of the flat grinding on the flat light. Serious wear gear teeth should be replaced with new gear, if only the ends of the gear wear, grinding grinding in the surface grinder. After changing the gear mapping, the modulus m = 3, the number of teeth z = 12, the tooth angle α = 20 °, the tooth top height coefficient f0 = 1, the tooth positive displacement coefficient x1 = x2 = 0.5, The dimensions are calculated as follows.

Diameter circle: d = mz = 3X 12 = 36 (mm)

Tip height: ha = m (f0 + x) = 3X (l + 0.5) = 4.5 (mm)

Dedendum height: hf [= m (f0 + cx) = 3X (l +0.25-0.5) = 2.25 (mm)

Tooth full height: h = ha + hf = 4. 5 + 2. 25 = 6. 75 (mm)

Tip diameter: Da = d + 2ha = 36 + 2X4.5 = 45 (mm)

Fixed chord thickness: Sxn = m (Ï€ / 2 * cos2a + xsin2 a) = 3 X (1.387 +0.6428X0.5) = 5.125 (mm)

Fixed chord thickness measurement tooth height: hxn = m (Ï€ / 8 * sin2a + xsin2 a) = 3X (0.7476X0 117X0.5) = 2.42 (mm)

Modulus m3 displacement coefficient x0

Tooth angle o20 ° fixed chord thickness Sxn5

Tooth fixed high coefficient f1 fixed tooth thickness measured the highest tooth height hxn2

Number of teeth z12

(2) shaft wear repair

Gear pump shaft wear is mainly due to friction between the ends of the shaft and the support needle roller wear, so that smaller shaft diameter. If it is slightly worn, the shaft can be enlarged by plating a hard chrome to make the shaft repaired. If the shaft wear serious, 45 steel or 40Cr steel should be re-manufactured, shaft rough rough, fine car, the bearing parts to be heat treated, the hardness of HRC60-65, and then grinding, the bearing surface roughness Ra with parts Greater than 0.32μm; shaft roundness and cylindrical tolerance of 0.005mm; with the gear with the H7 / h6, the surface roughness Ra should not exceed 0.63μm.

(3) pump body wear and tear after repair

Pump body surface wear is mainly arc-shaped section of the suction section.If there is a slight wear, grinding stone can be used after burr deburring. The pump body is made of cast iron casting blank, severe wear and tear should be replaced when the new pieces. If both ends of the gear in the pump are repaired by grinding, the width of the pump should be changed to the same size as that of the two ends of the gear. The two ends of the pump after reworking should meet the technical requirements as shown in Fig.3.

(4) After the two end cover wear and tear repair

Gear pump end cover made of cast iron, there wear phenomenon, the slight grinding flat on the flat grinding, wear more serious grind on a flat grinder. After grinding the end cap and the pump body with the connection plane contact should not be less than 85% flatness tolerance, the end of the hole centerline vertical tolerance, the tolerance of the parallelism of both ends and the center of the two axis hole Line parallel tolerance are O.Olmm. After grinding the surface roughness Ra should not be greater than 1. 25μm.

(5) pump needle roller bearings repair and replacement

After the pump parts repair, the needle roller bearings should be replaced. Needle on the needle is: the size of the needle roller diameter error should not exceed 0.003mm, the length tolerance of 0.1mm, and the shaft with the gap should be around O.Olmm; needle roller assembly according to the number of requirements filled bearing shell, Needle roller to be arranged parallel to each other.