# Several problems in the design of hardware springs

1. What is the characteristic curve of a spring? What does it have to do with the stiffness of the spring? What is the difference between the characteristic curve of a constant stiffness spring and a variable stiffness spring?
The relationship curve between the spring load and its deformation is called the spring characteristic curve. The slope value of this characteristic curve reflects the stiffness of the spring. The characteristic curve of a constant stiffness spring is a straight line, and the characteristic curve of a variable stiffness spring is a curve.
2. What is the purpose of spring strength calculation and stiffness calculation? What are the main factors affecting the strength and stiffness of cylindrical spiral compression (tension) springs?
The purpose of spring strength calculation is to ensure that the spring does not appear plastic deformation and fatigue failure during operation. The purpose of spring stiffness calculation is to ensure that the spring has the required elasticity.
3. Knowing that the external load of the cylindrical spiral compression (tension) spring is F, the test analysis only increases the spring wire diameter d, the effective number of turns n, and the middle diameter D. Does the spring deformation increase or decrease?
Under the action of F, when only increasing d, the deformation decreases; when only increasing n, the deformation increases; when only increasing D, the deformation increases.
4. There are two cylindrical spiral tension springs. If their materials, spring wire diameter, spring middle diameter, end structure, etc. are exactly the same, only the effective number of turns is different, try to analyze their strength and stiffness.
The strength of the spring has nothing to do with the effective number of turns n, and the stiffness of the spring is inversely proportional to the effective number of turns n.