Because of the particularity of the mechanical structure and the position of the hydraulic actuator, hose is widely used in the pipeline design of the hydraulic system. Unlike metal pipes, hoses are flexible. So they are primarily used to allow relative movement between the parts connected to each end of the hose, and to simplify pipe placement and installation. It is much easier to arrange a hose to go around or through a series of obstacles than to bend and install a hard pipe. So what should be paid attention to when installing hydraulic hose pipe?
1) Determine the appropriate bending radius
Although many hose manufacturers are able to provide hoses that can be bent to a smaller radius than the recommended minimum curvature radius, it is important to avoid bending hoses that are less than the recommended minimum curvature radius to shorten their service life. Therefore, the tube layout must first provide sufficient bending radius. The bending radius of the hose after installation should not be less than 8~10 times of the outer diameter of the hose, the root of the joint at both ends of the hose is not allowed to bend, and a certain straight section should be retained, the length of which should not be less than 6 times of the outer diameter of the hose: in order to avoid sharp bending, the hose can be wrapped around the spring or support steel belt and other methods, so that the bending gentle.
2) Determine the hose length correctly
Since the hose is flexible, flexibility must be taken into account when determining the length of the hose. Depending on the type of hose, the hose can be lengthened by 2% or shortened by 4% when the pressure changes. This change in length can fatigue the hose wire layer and cause damage, especially at the junction of the hose connection. Therefore, to allow for the contraction of the hose, leave a little longer when shearing to compensate. If the length of the hose is not enough, two hoses can be lengthened by connecting them through the transition joint.
3) Avoid hose twisting
If the hose is bent in the same plane, when there is relative movement between the two connecting parts, it should be avoided to twist the hose, otherwise it will reduce the bearing capacity of the hose. The test results show that the service life of the high pressure hose can be reduced by 70% if the hose is twisted by 5°, and 90% if the hose is twisted by 70 °. To avoid distortion, draw a straight line parallel to the center line on the hose with chalk before assembly, so that it is easy to check whether the hose is twisted after installation.
4) The hose needs to be bent in multiple planes
Hose placement is usually carried out late in the design work, so finding the ideal path can be difficult. Multiple plane bends can often be avoided by reorienting the hose. If this does not work, a hose clip should be installed between the two bends, providing sufficient length on either side of the hose clip to release the tension in the hose wire layer. This length depends on the quality of the hose, the degree of bending and the wire layer of the hose, so it must be designed for different objects. Another alternative is to use a separate hose section for each bend in the plane, with a hose coupling and hose clamp between the two bends. However, this method is not only costly and takes a long time to install, but also increases the potential for leakage at the hose connection. So there is less adoption.
5) Provide protection
Hose manufacturers now offer a wide range of products with wear-resistant housings. About 80% of hose failures were found to be due to external physical damage, with wear proving to be the main cause. Wear is mainly caused by repeated friction of hoses against equipment surfaces or between hoses. To avoid wear, hose clips should be used to hold the hose in place so that it does not rub against adjacent surfaces. The clamp should be tight enough to prevent the hose from moving, but too tight may damage the hose. The hose on both sides of the clamp should leave a suitable margin to compensate for hose expansion. Further protection can be provided by a sleeve, a spring-like metal sleeve that protects the hose from being squeezed. The flexible casing prevents the hose from being worn out. Some types of casing must be installed along the hose starting at the unconnected end of the hose. Casing with openings along the length should be installed without disconnecting the hose ends. Both types of casing are capable of strapping multiple hoses together. The contact and friction between the hose and the machine or the driving shed should be avoided as far as possible to prevent the wear and tear of the outer adhesive layer and the wire braiding layer. In areas where mechanical friction with the outside world may occur, canvas tape or rubber hose should be wrapped for protection.
6) Adapt to exercise
In addition to torsion and wear, the hose is not properly adapted to the movement of the working device. That would also cause it to break down quickly. For example, when connected to a swinging hydraulic cylinder. Hose length and placement must be appropriate to avoid tangling or bending beyond the recommended minimum radius. When multiple lengths of hoses are lined up close to each other. A part of the tube will move linearly, and a hose conveyor should be used to keep the hose in order to avoid tangling, twisting and rubbing against each other. Some special types of hose conveyers also protect against possible external conditions such as falling objects, friction, chemicals, or high temperatures.