Standing and Permanent Deformation Test of Cylindrical Spiral Spring

Standing is the basic requirement for the cylindrical spiral spring. The finished spring must be standing, so as to avoid the permanent deformation of the spring and affect the performance and normal work of the mechanical equipment or parts. As a leading spring manufacturer, let Cailong explain to you how to do the standing and permanent deformation test.

The method of inspecting the spring standing is to check the residual deformation of the spring. Generally, the compression spring is pressed together, or the load of the tension spring and torsion spring is added to the test load or the load specified in the drawing, and then loaded and unloaded repeatedly. After loading, the permanent deformation (residual deformation) of the spring without standing treatment is the largest for the first time, and then decreases gradually, and its geometric dimension remains unchanged after several times. Standing test is usually repeated three times. However, it should be pointed out that the free length (angle) of the spring before and after loading should be within the tolerance of the drawing.

The measuring tools used for permanent deformation detection include: vernier card with accuracy not less than 0.02mm or vernier height ruler with the same accuracy, steel tape, three-level accuracy plate, spring load testing machine, tool microscope or projector.

The detection procedure of compression spring is generally as follows: measure the free height H0 of spring, calculate the test height Hs, and the compression height Hb; if Hs>Hb, compress the spring to Hs for three times; if Hs≤Hb, compress the spring to Hb for three times, but the maximum load applied to compress the spring to be parallel tight shall not exceed 1.5 times of the theoretical parallel tight load; measure the free height H0'after three times of compression; obtain the permanent deformation Δ= H0-H0'.

The testing procedure of tension spring and torsion spring without initial tension can refer to the testing procedure of compression spring.

For the tension spring with initial tension, the free length of the spring remains unchanged after standing test, but the initial tension decreases step by step, and the corresponding initial deformation also decreases step by step. Because the change of the initial deformation cannot be reflected in the free length, the inspection method is not to measure the length, but to measure the load.