There are many reasons for the failure of the breaker, such as insufficient nitrogen pressure, insufficient load on the accumulator, and insufficient oil pressure, but internal leakage is mainly due to roughening of the piston or cylinder.
The main causes of piston pulling are described below.
As the core part of the breaker, the piston has extraordinary functions. However, there are many controversies caused by the longitudinal contusion of the imported piston. Therefore, the editor has sorted out some experiences and discussed the main reasons for the roughening of the piston, hoping to give some advice to customers. some reminders.
(1) The hydraulic oil is not clean
If the oil is mixed with sundries, as soon as such sundries are wedged into the gap between the piston and the cylinder, it can cause contusion. This kind of contusion has the following characteristics: usually there are grooves with a depth of more than 0.1mm, and the number is small , whose length is equivalent to the stroke of the piston.
(2) The gap between the piston and the cylinder is too small
This kind of thing usually occurs when the piston is replaced. If the gap is too small, the hydraulic breaker will work, and the gap will change with the rise of temperature. At this time, the piston and cylinder will easily cause contusion. Its characteristics are: the depth of the pull mark Shallow, large area, its length is equivalent to the piston stroke.
(3) The hardness value of the piston and cylinder is low
When the piston is moved by external force, due to the low hardness of the surface of the piston and cylinder, it is easy to cause contusion. Its characteristics are: shallow depth and large area.
(4) The drill rod guide sleeve fails
The guide sleeve is not well lubricated or because of the poor wear resistance of the guide sleeve, the wear of the guide sleeve is accelerated. The gap between the drill rod and the guide sleeve sometimes reaches more than 10 mm. At this time, the center line of the drill rod is easily deflected. When the piston moves to the drill rod At the tail, the reaction force received by the piston is an eccentric force, and a component force of this force produces a radial force acting on the piston. The piston is biased to one side under the action of the radial force, so that the original gap disappears and the oil film is destroyed. , produces dry friction, and quickly bruises the surface of the piston and cylinder. Its characteristics are that the bruise area is relatively large, about 1\/3 of the cylindrical area, and the bruise trace is short, which is equivalent to the displacement of the drill rod.
(5) The repair method is unreasonable
Not only can it cause contusion of the piston and cylinder, but it can even cause more serious consequences. When repairing the hydraulic breaker for a certain village, we found that in the stepped hole of the cylinder, the large hole near the end of the small hole has a very large taper. The average size of the cylinder is 0.28mm smaller, and the coaxiality deviation between the large hole and the small hole is more than 0.15mm. It is also known that the current user tried to repair the bruised cylinder by honing before sending it for repair, and prepared a New piston. After the test run, the piston stuck. After the disintegration, it was found that the piston and the cylinder had a large area of contusion. The reason was that the repair method was unreasonable. It is not recommended to use honing to repair the contusion or worn stepped inner hole , in view of the fact that the structure of the honing head is not suitable for grinding stepped holes, and because the honing head is relatively different from the product workpiece, honing processing is not suitable for repairing the cylinder block that has been bruised by the hydraulic hammer.
