This paper briefly introduces the design method of the die strong spring, and points out the main problems affecting the development of the strong spring.

In recent years, with the development of die and mould industry, the application quantity and variety of die spring, especially the special section steel wire die spring, are increasing day by day. The special section die spring has the characteristics of high rigidity, long service life, small volume and so on. But its design theory is slow. At present, the design method of square cross-section spring is relatively mature, the other section design method of strong spring, basic is according to the specific section through the test, to find out the design formula of correction coefficient of the cross section, we give a brief introduction to the characteristics and design of spring.

The problem is that the use of this spring is very concerned about the problem must also be clear. The following is a comparison of the square cross section and the circular section helical spring.

In the same space, the bearing capacity of the steel wire spring with square section is higher than that of the circular section spring 43 - - 48%. It is obvious that the rectangular spring is larger than 50%.

The main reason for the failure of the spring is that the use of stress is too large. Under the same conditions, the service life of the steel wire spring with the special section steel is increased by 13 - 14%.

Special section steel wire spring can produce large deformation.

The weight of profiled wire spring.

The linearity is better than that of the circular section spring, that is, the stiffness tends to be constant. In particular, a spring with a long edge parallel to the axis.

The scope of application is subject to certain restrictions: from the analysis can be seen, the special-shaped section of the material, such as the spring can not be fully applied to its advantages, it will not produce economic benefits, under what circumstances the use of good?

(1) the design load is less than that of circular section material.

(2) substituted circular section composite spring.

(3) when the spring is not able to reach the required deformation.

(4) where the spring is small.

(5) where the spring characteristics are strict.

Two, mold spring design principles

1 spring material allowable stress [R] choice should be to ensure that the fatigue life of the spring as the main consideration. The dynamic life of springs is generally divided into three categories:

Class I: the number of alternating load is 106;

Class II: alternating load for the number 10 - 105 fand;

Class III: alternating load is less than 10 fand;

2 material thickness ratio (a/b) should not be too large, and the spring that should not be too small.

3 design of special-shaped spring rectangular, must be derived and plotted in different rotation ratio, different thickness ratio and deformation correction coefficient (tau) and shear stress correction coefficient (beta) curve or formula.

4 according to the given conditions and constraints, the choice of calculation is simple and the design method of parameter selection is reasonable.

Three remaining problems

1 the low degree of standardization of the mold design, limiting the development of standardized mold spring.

2 die spring low degree of standardization, in addition to the current automobile industry developed standard QC7111 - 7113 external no domestic official use of the national standards or industry standards I, mold design standard optional is a problem to be solved urgently.

3 the design theory is not perfect, the more mature is the rectangular section spiral spring, but there is no conclusion about its tolerance selection. The spiral spring of the special section is based on the rectangular cross section and is modified by experiment.

4 do not have the production of special-shaped cross-section of the fixed-point plant, in particular, there is no such material of oil quenching and tempering steel suppliers. By the spring factory of its own restructuring of the material, the quality is not stable, high cost, the impact of such a spring to promote the application of.

5 no special spring coiling equipment for producing such spring. Die with spiral spring winding ratio is generally less than 4, while domestic spring coiling machine for winding up