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It is very important to understand and master the design steps of hydraulic cylinders when we design hydraulic cylinders, because knowing these steps can make the design orderly and better design hydraulic cylinders of good quality.
The design content of hydraulic cylinders of different types and structures is different. Since the parameters are often intrinsically related, there are no rigid regulations for the design steps of hydraulic cylinders.
In general, the design procedures and steps should be flexibly selected according to the various materials and conditions that have been mastered, and repeated consideration and verification should be carried out until the design principles are met and satisfactory results are obtained.
General design work can refer to the following steps:
Step 1: Master the original data and design basis, mainly including:
(1) The purpose and working conditions of the main machine;
(2) The structural characteristics, load conditions, stroke size and action requirements of the working mechanism;
(3) The working pressure and flow rate selected by the hydraulic system;
(4) The actual situation of materials, accessories and processing technology;
(5) Relevant national standards and technical specifications, etc.
Step 2: According to the motion requirements of the main machine in the design basis, perform a force analysis on the hydraulic cylinder and select the type of hydraulic cylinder and the structural form and installation method of each part.
Step 3: According to the external load force that the hydraulic cylinder can withstand (including gravity, external mechanism movement friction, inertia force and working load, etc.), determine the load change law of the hydraulic cylinder at each stage of the stroke and the power value that must be provided and other related technical data.
Step 4: Determine the piston end surface area and calculate the piston diameter (i.e., cylinder bore diameter) and cylinder outer diameter based on the hydraulic cylinder’s workload and the selected rated (working) pressure.
Step 5: Determine the diameter of the piston rod based on the ratio of cylinder diameter to movement speed or the working load and allowable stress of the material.
Step 6. Determine the pressure and flow of the hydraulic pump based on the movement speed, working output and piston diameter.
Step 7. Select the structural form of the cylinder head and calculate the thickness and connection strength between the cylinder head and the cylinder barrel.
Step 8: Determine the maximum working length of the hydraulic cylinder according to the working stroke requirements. Generally, the maximum working length should not be less than the diameter of the piston rod. Since the piston rod is slender, the longitudinal bending strength, stiffness verification and hydraulic cylinder stability calculation should be performed.
Step 9. Design guiding, sealing, dustproof, exhaust and buffering devices.
Step 10: Draw assembly drawings and parts drawings, and prepare technical documents
Step 11: Review all design calculation data and make modifications and additions.
The design content of the hydraulic cylinder is not static. Depending on the specific situation, some content can be omitted or added.
The design process may require repeated modifications to obtain a correct and reasonable design result.
The correct design and use of the hydraulic cylinder directly affects its performance. In this regard, problems such as improper installation of the hydraulic cylinder, eccentric load on the piston rod, drooping of the hydraulic cylinder or piston, and instability of the piston rod are often encountered.
Therefore, when designing a hydraulic cylinder, it is necessary to consider the type selection, parameter calculation, structural design and installation of the hydraulic cylinder to avoid the above problems as much as possible.
