Manufacture of constant-force springs
A spiral spring with uniform coiling diameter
Constant force springs are spiral springs with a uniform coiling diameter that deliver an almost constant force across the entire working range. This property contrasts with that of standard helicoidal springs, which follow Hooke's law and feature a linear increase in force with displacement. Constant-force springs offer low hysteresis and high fatigue resistance.
Specific features of constant-force springs
Push-pull and rotary movements
Constant-force springs are made from a pre-stressed metal strip that is wound into contiguous coils. They unwind without significant variation in force over the entire unwound length. Constant-force springs can be used for traction, return, or push-pull action, as well as to generate linear or rotary movement. CGR manufactures constant-force springs from strips ranging in width from 2 to 200 mm and in thickness from 0.05 to 0.60 mm. These strips are made from textured carbon steel, stainless steel, and special alloys. Springs can be greased, pre-tensioned, marked, assembled automatically, and mounted in plastic casings.
A most versatile spring design
Automotive, household and electric applications
Constant-force springs are ideally suited for linear motion applications, such as vehicle roof roller blinds. Combined with a damper, they enable smooth, constant-speed motion for cup holders, ashtrays, and storage compartments. For higher force requirements, multiple springs can be used. Constant-force springs are also found in push trays in retail displays and in the lifting and height adjustment of screens and medical equipment. They are also used in electric motors to ensure constant pressure of the carbon brush on the commutator.
CGR relies on its STRAIN advanced research laboratory to develop specific technical solutions for the complex problems of sizing and manufacturing spiral springs.
