Use hoses to understand hoses. Due to the variety of hydraulic hoses and the variety of construction, combined with different operating conditions, the service life of hydraulic hoses depends not only on the quality but also on the correct use and maintenance.
The reasons for the failure of the hose are: improper installation and use, unreasonable system design, and unqualified hose production quality. How to judge the quality of the hose? The following methods of initial judgment are provided:
One, outer rubber layer failure
1, the appearance of cracks in the appearance of the hose: in the cold environment, the appearance of cracks in the hose will cause the hose to be bent. If you find a crack on the surface of the hose, you should observe whether the glue in the hose is cracked, and decide whether you need to replace the hose immediately.
2. Blisters appear on the appearance of the hose: Blisters appear on the appearance of the hose because the quality of the hose is unqualified or improperly used.
1 If bubbling occurs in the middle section of the hose, which is mostly a problem with the production quality of the hose, a qualified hose should be replaced in time;
2 If the bubbling occurs within the range of 15mm-20mm between the hose and the joint, it is probably due to improper installation of the joint.
3, the hose is not broken but there is a lot of oil seepage: This phenomenon is due to the fact that when the hose passes through the high-pressure liquid flow, the inner rubber is filled and scratched, and the large-scale leakage of the paper results in a lot of oil leakage. This phenomenon usually occurs at the bend of the pipe. Check the replacement hose and ensure that the bend radius of the hose meets the technical requirements in use.
4. The outer rubber layer of the hose is seriously degraded and micro cracking occurs on the surface: This is due to the natural aging of the hose for a long time. Due to ageing and deterioration, the outer layer is continuously oxidized to embrittle the surface layer, and the embrittlement layer is deepened when it is aged. In use, minor cracks can cause minute cracks. In this case, the hose should be replaced in time.
Second, the inner layer failure
1. The rubber layer in the hose is hard and cracked: This phenomenon is generally caused by the impure plastic material. If only the internal rubber under the broken hole of the hose is hard and the top is well maintained, this indicates that the hose rupture is over-squeezed. , Bending too fast or torsion, etc. will cause the fluid to heat up and accelerate oxidation, which will cause the glue to harden.
2. The rubber layer in the hose is seriously degenerate and swell: This phenomenon is due to the hydraulic oil used in the time of the expiration or oxidation degradation of the dirt present in the hydraulic system, the hose is subject to chemical changes and deterioration, will find broken rubber at the return port sheet. If this happens, check the physical and chemical indicators of the hydraulic oil and check the compatibility of the system oil and the inner rubber material and the operating temperature to meet the standard.
Third, the enhancement layer failure
1. The hose is broken and the braided steel wire near the breakage is rusted: When the outer rubber layer is peeled off, it is found that the weaving and winding of the steel wire are rusted near the breakage, which is mainly due to the wet or corrosive substances in the outer layer. This situation is generally accompanied by outer layer fractures, scratches, or severe deterioration. The outer rubber layer loses its protective effect on the reinforcing layer; if the break occurs within 200 mm of the joint crimping location, the reason is that the joint is mostly unqualified. Causes cracking.
2. The hose is enhanced to become rusted, but the phenomenon of irregular broken wire occurs: The main reason for this phenomenon is that the hose is subjected to high-frequency impact force. There are many intersections between the steel wire and the steel wire of the reinforcement layer. When the pressure in the hose changes greatly, these cross points will also rub along with each other due to changes in the pipe diameter, resulting in wire breakage. For the pipe that is often subjected to high frequency impact, the steel wire winding skeleton should be used as the reinforcing layer.
Fourth, break the fault
1. The hose is broken at one or more points and the gap is neat: Generally, the pressure of the system exceeds the pressure resistance of the hose.
2. Torsion at the rupture of the hose: Mainly due to excessive twisting of the hose during installation or use. Excessive torsion will lead to changes in the structure of the reinforcing layer and reduce the pressure resistance of the hose. The hose is easily broken under high pressure. Therefore, the axis of the joints on both ends should be set on the same plane.
3. The wire loops appear at the break of the hose and there is a noticeable tightening phenomenon: The main reason is that the hose is excessively stretched and the separation of the layers reduces the pressure resistance. In general, the amount of expansion and contraction under high pressure is normally 2%-4%.
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