液压与气压传动Chapter_4 (2).ppt

2. Makeups Cylinders can be further divided into cylinder block assembly, piston assembly, sealing device, cushion device and venting device. （1）Cylinder block assembly Fig. 4-15Cylinder barrel and cylinder cover connection a)Flange type b) Semi-ring type c) Thread type d) Pull-rod type e) Welding type 1-Cylinder cover 2-Cylinder barrel 3-Press plate 4-Semi-ring 5-Stopping nut 6-Pull （2） Piston assembly Fig. 4-16 Pistons and rods connection 1-Piston rod 2-Piston 3-Seal 4-Against looseness gasket 5-Nut 6-Clip key 7-Ring set 8- Spring collar （3）Cushion devices Fig. 4-17 Cylinder cushion device Circular cylindrical void b) Circular cone void c) Variable throttle groove d) Adjustable throttle orifice （4） Venting devices Fig. 4-18 Exhaust elements a) Type of valve b) Type of plug 4.2.3 Main dimension calculation The cylinder structure dimension has a direct relationship with the working mechanism of the mainframe. 1. Problems for attention (1) On the precondition of proper speed and suitable thrust, each part of the cylinder must be designed according to related standards. The cylinders should be as compact as possible and convenient to machine, install and maintain. (2)The piston rod is in tension under the heaviest load. If the piston rod is in compression, it should possess a good longitudinal stability. When long stroke piston rod extends out, auxiliary support is needed to prevent the piston rod from drooping. (3) Only one end of the cylinder can be fixed for position for installation or fastness to ensure non-obstruction for cylinder’s expanding with heat and contracting with cold. (4)Whether the cylinder system needs cushions, venting and dustproof devices or not must be determined based on the concrete working conditions. 2. Main dimension calculation （1）Inner diameter D of the cylinder tube （2）The diameter d of the piston rod （3）Cylinder tube