新闻资讯

Alignment of cylinder barrel and piston rod
1 Long cylinder bending and straightening machine
After bending of cylinder barrel and piston rod due to accident, it is generally necessary to straighten them on the press. However, the cylinder barrel or piston rod straightened on the press often rebounds after a period of time, that is, the cylinder barrel or piston rod restores its original shape to a certain extent. For this reason, some repair plants have developed long cylinder bending and straightening machines (see Figure 30). When using, put the bent cylinder barrel or piston rod into the straightening machine, press the pressing wheel, start the motor, roll back and forth, adjust the pressing wheel according to the situation, and then straighten the bent cylinder barrel or piston rod slowly. This is different from the straightening on the press. Straightening on the straightening machine can not only straighten the bent parts, but also release the internal stress caused by the bending of the cylinder barrel or piston rod under the repeated action of the upper and lower rollers to ensure that it will not rebound after straightening.
Fig. 30 Long cylinder bending and straightening machine
1 Base 2 Gantry (with guide rail inside) 3 Compacting straightening wheel 4 Compacting wheel 5 Adjusting screw 6 Handwheel 7 Driving wheel 8 Driven wheel 9 Driving pinion 10 Driven gear 11 Reducer 12 Motor
Before the cylinder barrel or piston rod enters the straightening machine, a certain amount of pre straightening shall be carried out to control the bending before it is put on the machine within a certain range (see Figure 31). As shown in Figure 31, there are two curved long cylinders, which are often encountered when straightening on the straightening machine. The large bending H allowed by the equipment is the large distance between the upper and lower rollers in Figure 30.
For hydraulic cylinders (L/d>15, such as crane boom telescopic cylinders, outrigger horizontal cylinders, etc.) with large length diameter ratio (i.e. the ratio of piston rod length L to piston rod diameter d), the piston rod is prone to instability and bending due to its large stroke, hinge at both ends, hydraulic cylinder dead weight and load eccentricity, and different methods should be used to straighten according to the size of the outer diameter of the piston rod.
After bending, the piston rod with smaller outer diameter (d ≤ 55, such as the piston rod of the outrigger horizontal cylinder) can be straightened with a jack, as shown in Figure 32. First, weld an inverted L-shaped steel frame 3 on the steel plate 1 (if necessary, weld the reinforcing rib), level the two ends of the piston rod with square wood, and place the jack between the steel frame 3 and the piston rod (note! A certain thickness of cotton yarn must be used to separate the piston rod and the jack). Then slowly extend the jack rod and press the bent piston rod. After visual inspection, press the jack rod tightly and hold it for about 15min, and then press it again. The second jacking shall make the piston rod axis slightly bend in the opposite direction of the original bending. After 20 min, open the jack check valve to relieve the pressure. If the piston rod axis is straight through visual inspection, then conduct straightness inspection to meet the requirements (1000:0.06).