Design and manufacture of ultimate recovery force miniature piston return spring

2020-02-04 13:07:27

1. Piston 2. Limit cylindrical pin 3. Cylinder block 4. Sealing ring 5. Oil inlet 6. Oil output 7. Cylindrical pin 8. Design of cylindrical compression spring for return spring ultimate restoring force In order to make full use of cylindrical compression spring The ultimate allowable stress of the material, according to the working conditions of the cylindrical compression spring, the diameter of the primary spring wire

1. Calculate the working limit load of the spring.

The ruler is the curvature coefficient of the spring, considering the coefficient of the influence of the curvature of the spring wire on the shear stress. According to the derivation calculation and practice, the winding ratio or the spring index is the working limit shear stress, and is activated when working on the type 1 load spring. The load, when damaged, will cause the failure of the whole mechanism or the number of times the load is applied. The number of times of the spring or the variable load that is uniformly increased by the static load or load during the operation of the load spring is 52l.67ãƒ¬. In 5 times and the spring 1.26 subjected to the impact load, the spring of the type 1 load spring is not important or the number of times the load is subjected to a variable load of 103 or less. 21.12. The allowable shear stress of the spring material. In order to maximize the allowable shear stress of the spring material, the design is manufactured using a strong pressure treatment. The spring after the strong pressure treatment can increase the allowable shear stress of the spring, and the maximum can be increased by about 25. In the case of strong pressure treatment, the free height of the cylindrical compression spring is made larger than the free height piece of the cylindrical compression spring after forming. The spring is pre-compressed beyond the yield limit of the material and unloaded for a fixed period of time before being shaped. Its role is to produce a spring load bearing capacity opposite to the stress on the spring wire surface. After the strong pressure treatment, the allowable shearing force of the spring wire can take the limit load. 2. The effective number of cycles of the cylindrical compression spring is determined according to the working limit load 6 and the maximum compression displacement of the cylindrical compression spring required by the working conditions. When designing the circle, it requires a few 2. If 20, it is rounded to the whole circle, 20, and rounded to 12 turns. For safety, when rounding, turn to the large modern workmanship lungs in the direction of the 2,026.

In order to reduce the size of the cylindrical compression spring, thereby reducing the volume of the cylindrical compression spring, and ensuring that the shear stress of the spring spring wire does not exceed the allowable ultimate shear stress when the working limit load is exceeded, the design can be used. At the maximum ultimate load, the spring coils of the springs are basically tight, and the pitch of the spring is the final determination of the free height of the cylindrical compression spring. When the ends of the ring are tight and smooth, take 341 or 54 turns at each end. Support ring. A column compression spring that satisfies the requirements of the outer diameter of the outer diameter, the maximum working load, and the minimum free height is obtained.

The spring parameters calculated by the above method are as follows: diameter of the spring wire = 1.6; medium diameter, 2 = 10; material 65 elbow 1 strong pressure treatment; working limit load, = 140 maximum compression displacement 2 = 15; effective number of turns = 7 turns , pitch = 3.74; both ends of the circle and close the number of flat turns, = 2; free height is good. =28.6; initial compression displacement 1 ultimate compression force of the cylindrical compression spring manufacturing with ultimate restoring force The key to the manufacture of the miniature piston return spring is the use of strong pressure treatment, which is to improve the bearing capacity of the compression spring. An important means. After the spring is subjected to the strong pressure treatment, the elastic limit yield limit of the material can be increased, and the surface of the spring can generate residual stress opposite to the working stress.

The basic principle of the strong pressure treatment is to prefabricate the spring to a higher degree of freedom than required, and then compress the spring to tightness so that the stress exceeds the elastic limit of the spring material. When the stressed spring is reloaded, its allowable elastic limit is much higher than before the strong pressure treatment. Therefore, the spring treated with high pressure can be used with higher design stress. The strong pressure treatment method uses a long time and strong pressure, and the holding time is 481! . The high pressure treated cylindrical compression return spring has the characteristics of small volume, light weight and large restoring force, and can meet the requirements of cylindrical compression return spring in portable electric or manual hydraulic and pneumatic tools or other miniature hydropneumatic components.

Due to the strong pressure treatment, the spring will be permanently deformed. The compression spring often makes the free height of the spring higher than the free height required for the work. The rule of the spring free height that reserves the amount of compression deformation is called pre-system. The factors that affect permanent deformation are complex, so accurate calculation of prefabrication height is very difficult and can only be estimated empirically.

The author estimates the prefabricated height Dan of the first piece as follows.

The free height of the finished spring product, ie the free height required for the work.

For example, the spring manufactured by the calculation of the value obtained by the formula 8 can not meet the tolerance requirements of the load or the free height after the strong pressure, and the design and manufacturing method of the micro-piston returning cylindrical compression spring with the built-in structure of the compression spring can be adjusted proportionally. It is widely used in the design and manufacture of piston return cylindrical compression springs in portable electric or manual hydraulic and pneumatic tools or other micro hydro-pneumatic components.

1 Lin Guozhong, Sheng Dongchu. Hydraulic drive and control. Beijing Beijing Institute of Technology Press, 1986 2 Sun Yu'an. The application of hydraulic technology in engineering is elbow. Nanjing Jiangsu Science and Technology Press, 1986 3 Pang Zhenji, Zhang Shuguang. Instrument parts and institutional brothers. Tianjin Tianjin University came out with 4 Luo Hui. Mechanical spring manufacturing technology 1 cubit. Beijing Machinery Industry Press, 1987 Received 20020205 Modern Engineering Project 20026

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