Straightening method of pump shaft

 This method can be used when the shaft diameter is small and the bending is larger. The shaft on the triangular notch block within the frame, or on the machine by the thimble against the ends of the shaft, and the shaft bending convex vertex at. Use of screw press and hold the convex vertex, down pressure, until the axis until the alignment. 

 Larger diameter and bending of the shaft can be used in this method. This method is the use of concave bending twist rod to beat the cold shaft, the shaft extension and more straight here at the surface. The twisting rod is made of a material that is lower than the hardness of the pump shaft, or a copper sleeve on the material with high hardness, and the edge of the twisting rod must have a corner of the garden. 

 In the straight axis, the axis of the concave upward, and supports the largest living curved convex vertex. With downward pressure, then the use of 1-2 kg hammer twist rod, so that the concave axis material and extension by beating. Twisting, starting from the lowest concave central beat, gradually moved to the sides, and along the circle of the arc on Wednesday, but the central tap density should be greater. 

 Volume axis alignment with the beat frequency is usually in direct proportion. Note the initial beating, shaft alignment faster, slower after. Should pay attention to grasp the beat, do not damage the surface of the shaft. 

 When the small amount of bending (for axial length less than 1%), can be in a cold state with straight screw jack. In straightening, taking into account the axis of the rebound, to have some, in order to ensure the correct axis after the comparison of integrity. The accuracy of this method can reach 0.05-0.15 mm per meter. 

The convex curved upward, wrapped with asbestos cloth around, and then use a blowtorch or hot gas welding urgency. About material temperature low critical temperature of 100 degrees celsius. Hot, because the metal plastic deformation, so that the surface is shortened after cooling has been stretched, but has been unable to restore the original state, resulting in bending and original bending opposite, the convex surface is flat and straight shaft to achieve. As in the concave heating fire their thermal elongation, the better. 

Heating method, should be uniform, isometric (about 20 mm from the axis), from the center outward, and then by the outward center to keep the temperature. 

The heating area and the shape are heated by the axial opening (axial length and the radial short) method, so that the radial direction temperature is uniform, so that the shaft is not easy to distort. While the radial opening (radial long and short axis) method is used for heating, the effect of the straight shaft is obvious. 

When the first shaft straightening, flat on the two support, the bending part convex upward, and the maximum bend axis with a wet stone cotton bandage. This stone cotton axial opening of 0.15d * 0.2d or 0.35d * 0.2d radial opening (D is the diameter of the shaft) of the rectangular opening, and then in the opening with oxygen acetylene flame heating 3-5 minutes (the strength of welding torch, and the oxygen pressure 4-5 to atmospheric pressure), the temperature reaches 500-600, with a dry asbestos cloth covering the heat at last, heat 10-15 minutes, with compressed air, make rapid cooling. The variation of bending shaft by the dial indicator. Repeat, a straightening straightening shaft can not, should be carried out in the low temperature annealing heating, heating the shaft to rotate and slow to 300-350 DEG C and maintained at this temperature for more than an hour, and then wrapped with asbestos cloth heating, it slowly cooled to 50-70 DEG C, so that we can eliminate internal stress. 

Changes in the process of straightening shaft and shaft of the material for a performance. When the heating is heated, the bending deflection of the shaft end is gradually increased to the maximum, which is due to the expansion of the metal after the convex part is heated. After cooling, the bending deflection of the shaft end is gradually reduced to the minimum, which is the result of the rapid cooling of the metal fiber. 

The principle is because the metal material has relaxation properties, i.e. parts under high temperature stress decreased at the same time, parts of the elastic deformation and plastic deformation to reduce the proportion of the amount of increase, if coupled with a certain direction of the load, it can control the direction of deformation and size. When the load is lifted, it is mainly due to plastic deformation, so few rebound, so as to achieve the purpose of straight. Heating tool with multiple induction coil, the straight shaft should be carried out after the annealing. This method is applied to the large axis. 

The shaft is fixed in advance, the convex upward, and then use the load will bend under axial pressure, the convex surface caused by compressive stress, and then at the concave heating, can also direct axis. This method is only applicable to the axis with smaller bending degree.