Ming Tai presents some Engineer’s Tips of Variable Force Springs and Variable Torque Spring.
Variable force spring and variable torque spring can be unfolded negative gradient, positive gradient compounded in a spring. It breaks through the influence of the traditional spring that is affected by Hooke's law, so that the stroke and the force are no longer proportionally increased, but along with various elastic force-displacement combinations, such as negative slope. So, stepped constant force can be achieved.
Here we make some examples which show relations between load (force or torque) and stroke, these can be used on specific occasion for engineering reference.
Pen Type Drug Injector Application
The spring exerts constant force to keep the drug flow fixed, preventing the patient from feeling uncomfortable when applying it. It features stretch force in end of the stroke to ensure all drug can be injected entirely. (See Example-1).
Fireplace up-down Slide Door
Variable force spring can be applied to up-down slide door of fire place.
When the door is closed, the spring force is less than the weight of door; while the door in middle stroke, the spring force is equal to the door weight. When fully open, the spring exerts force greater than the door weight to secure the door does not slide down. (See example-2)
Point of Purchase Display
Variable force spring can be applied to point of purchase display. The spring export variable force to match the quantity of display items. While the large force can ensure push large quantity display item smooth, the small force push small quality items availably and avoid flattening the display items. (See Example-3).
The variable torque spring can be applied to cordless shade, it makes user to adjust curtain up and down easily. The spring exerts smaller torque step by step, which generate balance of gravity to allow the curtain to stop at any height. (See example-4).
Engineers are welcome to contact Ming Tai for more application tips in the design phase.