Our factory Shaanxi TY 640 type rotary rotary printing machine used only 4 years to make an abnormal situation: the impact noise of the gear box obviously increased. With a period of time, the machine operation is heavy, the vibration is great, and it is difficult to start after shutdown, the problem is very Seriously, it was once halted for six months.
We found in the examination of the gear box demolition that the outer end discs of the large double gears have broken two teeth, and several adjacent right tooth surfaces of each broken tooth have been severely worn and become pits; the second axis of the helical gear The discs and the adjacent small spur gears also have several teeth with different degrees of damage at the outer end and a tapered cone; the bearing seat supporting the inner end of the second shaft is out of control because the fastening bolts and the positioning pins are all loose. These damaged gears have one thing in common, that is, the damage part is at the outer tooth end (machine transmission side). For example, the inner end meshing teeth of the large double gear and small spur gear are intact.
From the above analysis, the cause of the gear box transmission gear damage is directly related to the out-of-control positioning of the second shaft inner end bearing seat. From the force analysis of the gears, we know that the gears meshing with the drive, the force between their teeth moves in the direction of the pressure line on the involute tooth surface, and this force constitutes two mutually perpendicular component forces: one is to promote The circumferential force of the rotating gear, which is cut in the pitch circle; one is the center of the wheel facing the two gears in the opposite direction, and has a radial force against the separation tendency. Therefore, because the second shaft end bearing seat is out of control, the inner end of the shaft must be affected by the force between the teeth, causing the two shafts to be in parallel, the teeth are not stressed uniformly, and the teeth are stressed. The tooth end is partially stressed, and the involute tooth form is abraded at the outer end at a tooth width of about 1.5 cm. The drive is unstable and noise occurs. As the large double gears pass through the double-crank linkage mechanism, the platen is accelerated at a certain speed ratio. In addition to the reciprocating movement, another double crank mechanism is driven to make the roller cooperating with the periodical variable speed rotation so that the helical gears and the spur gears on the second shaft are affected by the cyclic load of the double crank mechanism during the process of receiving or transmitting the power. , And produce strong bounce and shock vibration, so that the tooth gap of the meshing drive increases, and the gear item collides with the honing tooth surface, resulting in severe wear and deformation of the gears on the large double gear that are subject to large impact force, and finally due to bending of the gear teeth. Fatigue strength is not enough and it breaks.
For the treatment of large double gear tooth breakage, we consider from multiple factors, without disassembly, using the rooting surfacing method to repair, that is, drill holes in the appropriate position of each broken tooth surface with 8.5 two bottom holes, under attack M10 The silk mouth is one cone deep, the M10 ordinary snail is rooted tightly here, and is formed by spot welding of “a weld-cast 308” pure nickel cast iron electrode, and then slowly corrected with a trowel and other tools, and the tooth is measured by the lead cast tooth model. Shape, measure the length of the common normal to ensure accuracy, and other damage teeth are also repaired accordingly.
Before the assembly, loosely place the detached bearing housing on the housing. After the cabinets and other parts were installed in sequence, and after the disc brakes were checked for safety and reliability, under the lubrication conditions, the test machine had no abnormalities for 3 days, and it was put into normal production. It worked well for more than one year.
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