The detection and design function of the characteristics of tension spring and compression spring spring:
1. The characteristics of the spring and its limit error
The characteristics of the tension spring and compression spring should be suitable: under the load of the specified height (or length), the spring deformation should be between 20% and 80% of the deformation under the test load. When the first level of precision is required, the spring should be specified The amount of deformation under high load should be above 4mm; when there is a special need to check the stiffness for characteristics, the amount of deformation should be between 30% and 70% of the amount of deformation under the test load.
Test load Fs When calibrating spring characteristics, the maximum load allowed on the spring is used as the test load.
Test stress τs: When calibrating spring characteristics, use the maximum allowable load on the spring as the test stress.
The limit error of the load F when the height is specified is defined in Table 1.
The limit error of the load F when the compression spring is at the specified height
When the number of useful turns of the extension spring is greater than 3, the limit error of the load F under the specified length is defined as follows:
±[(initial tension F0×α)+(load-initial tension F0×β at specified length]
in the style
Α–The limit error of initial tension F0, as defined in Table 5-18;
β-the limit error of the load F corresponding to the deformation amount, as defined in Table 2.
The initial tension of the tension spring and the limit error α and β value of the load F
The limit error of the stiffness of the tension spring and compression spring is defined according to the table.
Limit error of spring stiffness F
2. Spring load and stiffness test
The load of the tension spring and compression spring can be tested and measured with a spring tension and compression testing machine, and the large spring can be tested and measured by the captain of the material tension and compression testing machine.
Spring tension and compression load testing machines mostly use the principle of leverage to convert the load value into a displacement value and predict it on the numerical dial. The primary specification function of the tension and compression testing machine.
Spring tension and compression load testing machine
Spring tension and compression testing machine specifications and functions:
The maximum distance between two hooks in tensile test/mm
Maximum stroke of tensile and compression test/mm
Compression test two pressure plate diameter/mm
The maximum distance between two pressure plates in compression test/mm
shape size length × width × height
Mm mm mm
The test precision of the load is not only related to the precision of the load measurement of the testing machine, but also to the precision of the reading of the length (or the amount of deformation) of the compressed spring during loading. In the measurement of the small amount of deformation such as the injector spring, the precision is relatively small. When the spring is high, a dry submeter can be added to the testing machine to improve the precision of the deformation reading, thereby improving the precision of the load measurement.
When measuring the load, attention should be paid to adjusting the “0” position of the testing machine, and the weight of the spring itself should be deducted. For slender springs that are not easy to stand up, the mandrel can be added for testing. In this case, you should just stop or reduce the center. The friction between the shaft and the spring does not affect the accuracy of the load measurement.
Whether it is a compression spring or a tension spring, when measuring the load, the applied load should be placed on the spring axis line or perpendicular to the target of the spring axis line, so that the spring will not be twisted when it is deformed. If it is a deformation When the amount is large, when a relatively large relative displacement occurs between the end face of the compression spring and the support platform of the testing machine, a light buckle method can be used to relax the spring to reduce friction. It can also be placed on the pressure plate or support flat top. Thrust bearings are used to eliminate the distortion of large deformation.