For hydraulic cylinders with higher pressure, thicker cylinder wall and larger cylinder diameter (φ63mm ～ φ320mm), the end cover and cylinder are connected by internal snap type, which has light weight, small size, simple processing and disassembly Convenience and other advantages. For example, it is very convenient to repair the piston to replace the seal, repair the guide sleeve, etc. At the same time, the end cover has the characteristics of radial floating, which makes the piston rod difficult to be clamped.
1. Structural design
The elastic retaining ring 2 is used to prevent the end cover from moving into the cylinder; and in Fig. B, the pressure ring 2 and the screw 4 are used to prevent the end cover from moving into the cylinder. The structure is suitable for hydraulic cylinders with relatively low speed (that is, the diameter of the piston rod is relatively small). This structure has a stepped shape in the inner diameter of the cylinder and the outer diameter of the pressure ring. By controlling the relative dimensional tolerance of it with the height direction of the cylinder body, the pressure ring is supported on the cylinder body with the shoulder, and the cylinder head is tightened by the pretension bolt 4 To ensure that when the hydraulic cylinder is unloaded, the snap key and the key groove are brought into contact on the load side, eliminating the fit gap and forming preload, so that the end cover 1, the pressure ring 2, the snap key 3 and the cylinder body 5 form an organic whole .
2. Design and installation of card key
2.1 Principles for determining the structural parameters of the key
The piston chamber of the hydraulic cylinder is under the action of pressure oil, and the pressure of the liquid oil acts on the cylinder head and is transmitted to the cylinder wall of the cylinder through the key. Therefore, the key is subjected to squeezing force and shearing force, and at the same time, a torque is generated to the key so that the key is twisted and deformed. The torsional deformation of the snap key is related to the structural parameters of the snap key (height of the cross section of the snap key), d (inner diameter of the snap key), and d2 (outer diameter of the snap key). Therefore, reasonable design should be comprehensively considered based on the above two factors. The key height h is a key parameter that affects the torsional stiffness and contact stress of the key. Therefore, the key height h should be based on the shear strength of the key and the torsional deformation of the key should also be considered, so h The value can be appropriately larger.
The outer diameter d2 of the key affects the torsional stiffness and the outer diameter of the cylinder. The inner diameter d1 of the key is related to its torsional rigidity. In general, the center of the cross section of the key should be the same as the inner diameter of the cylinder.
2.2 Installation of card key
After the key is processed into a circular ring, cut into three equal parts at 120 °. When assembling, first put the cylinder head into the cylinder barrel, you can push it in a little more, and then put the three equal parts of the snap key into the annular key groove of the cylinder barrel, and then gently pull the cylinder head out By the side of the full card key. Finally, install the pressure ring (or collar) and tighten it with bolts.