Home > Blog > Common problem > Design of constant force springs

Design of constant force springs

source:Qianye Precision time:2022-9-14
 A constant force spring is a spring that exerts a constant force over its range of motion. That is, it does not obey Hooke’s law. Typically, a constant force spring is constructed as a coiled band of spring steel so that the spring relaxes when fully coiled. When it is unrolled, the restoring force comes mainly from the portion of the belt that is close to the roll. Since the geometry of this region remains nearly constant as the spring unfolds, the resultant force is nearly constant.
      By creating a spring with a variable pitch, you can make a push-shape spring with a constant velocity. Placing a larger pitch in a larger outer diameter coil and a smaller pitch in a smaller outer diameter coil will force the single spring to fold all coils at the same rate when compressed.
      Design of Constant Force Springs: A constant force spring is a coil of prestressed tape that exerts a nearly constant restraining force against unwinding (Figures 1 and 2). The force is constant because the change in the radius of curvature is constant. This is the case if the change in coil diameter due to buildup is not taken into account. Long reach, constant torque and virtually no friction have led many designers to specify constant force springs in applications such as sliding doors and windows and height adjustment of computer monitors and fans, store display shelves or motor carbon brush motors . Constant force motor springs are also used to drive mechanisms for timers, movie cameras and cable retractors.

      Tension type constant force tension springs are supplied in coils with a natural radius of curvature R (Fig. 3). If such a spring is installed on the drum, the drum diameter should be 10% to 20% larger than its natural diameter. There should be one and a half turns on the reel. The active portion of the material is approximately equal to 1.25 times the diameter D. Therefore, the spring will not reach its rated load until the elongation is greater than 1.25D (Figure 1). The radius of curvature of the active part goes from R to infinity and a clearance is required. The recommended distance from the center of the drum to the straight section is 0.8 times the diameter D (Figure 3). Strips can become unstable when stretched for extended periods of time and should be guided to prevent twisting or kinking during recoil. The diameter of the idler must be larger than the natural diameter and must not be used to reverse the natural radius of curvature (Figure 4).

Depending on your application, a constant force spring may be ideal. Consultation with the spring manufacturer for constant force springs is recommended at the design stage. Qianye Precision specializes in the production and manufacture of high-precision clockwork springs, which are widely used in various electronic devices, household appliances, small toys, office supplies, communication equipment, medical machinery, electronic computers, windows, doors, vehicles, etc. The imported raw materials and domestic raw materials will continue to meet your requirements. The company has more than 20 years of experience in product development, production and manufacturing, and has become a well-known brand distributor in China.

Latest News

 Unbreakable: The Power of Stainless Steel Springs
Unbreakable: The Power of Stainless Steel Springs

Time:2023-7-6

Stainless steel springs, renowned for their durability and strength, have emerged as a force to be reckoned with in various industries. From automotive and aerospace to medical and construction, these unbreakable springs have proven their worth time and again. In this article, we will delve into the history, properties, and applications of stainless steel springs, exploring why they have become...

 Applications of Constant Force Springs
Applications of Constant Force Springs

Time:2023-8-29

Constant force springs, also known as clock springs or spiral springs, are mechanical devices that store and release energy in a controlled manner. They are widely used in various industries due to their unique properties and capabilities. In this article, we will explore the applications of constant force springs and their benefits. One of the major applications of constant force...

 The Benefits of Using a Constant Force Spring
The Benefits of Using a Constant Force Spring

Time:2023-4-22

Constant force springs, also known as flat springs or clock springs, are mechanical components that can provide a constant force over a wide range of deflections. They are widely used in various industries, such as aerospace, automotive, medical, and electronics, due to their unique benefits. In this article, we will explore the advantages of using a constant force spring. 1....

 High-efficiency choice: carbon brush holder springs help motor upgrade
High-efficiency choice: carbon brush holder springs help motor upgrade

Time:2024-4-12

On the road to motor upgrades, high efficiency, stability and durability have always been the core goals pursued. With its excellent performance and unique advantages, carbon brush holder springs are becoming a high-efficiency choice for motor upgrades. As a key component inside the motor, carbon brush holder springs not only optimize current transmission and improve motor efficiency, but also play...

 Optimizing Your Design: Elevating Your Product’s Potential
Optimizing Your Design: Elevating Your Product’s Potential

Time:2023-5-4

Design is an essential aspect of any product or service. Whether it's a physical product or digital service, the design is what sets it apart and makes it attractive to consumers. However, design is not just about aesthetics; it's also about functionality and usability. Therefore, optimizing your design is crucial to elevating your product's potential. One of the first steps...

 Spiral Torsion Spring: A Comprehensive Guide to Design and Applications
Spiral Torsion Spring: A Comprehensive Guide to Design and Applications

Time:2023-6-8

Spiral torsion springs are a type of spring that is commonly used in various applications such as automotive, aerospace, medical, and industrial machinery. These springs are designed to store and release energy when they are twisted around their axis. In this guide, we will provide a comprehensive overview of spiral torsion springs, including their design, materials, and applications. Design of...

Product