Design steps of constant torque spring

Constant torque spring is a constant force spring with special force moving between two spools. The spring is stored on the storage spool and wound reversely on the output spool. When released, torque is obtained from the output spool when the spring returns to its natural curvature on the storage spool.

The spring does not need to be connected to the storage spool. The spring can be installed in a cavity without storing the spool at all. However, friction will then be introduced and torque requirements will change. The torque generated by the constant torque spring will increase slightly after several revolutions. Constant torque, even negative torque, is also possible. Negative gradients of up to 50% can be achieved in some applications.

As for the design of constant torque spring, when considering the use of constant torque spring, it is strongly recommended that you talk with Qianye engineers and study various design parameters. Some initial design calculations can be carried out according to the following eight steps.

1. Select materials

Most of the springs we produce are made of type 301 stainless steel. This material is readily available and predictable. Thousands of industry engineers can assist in selecting standard sizes to speed up the process. We also use high carbon steel, Inconel and Elgiloy in various designs as needed.

2. Life expectancy

This is one of the most important considerations because the life of constant torque springs is very predictable. Practical is important because it is estimated that high life cycle requirements may lead to larger and more expensive designs. Of course, underestimating the life cycle can lead to premature failure.

3. Establish torque

When determining the correct torque for the spring, your design needs to consider many factors. Torque is only a measurable torsional force, which often leads to rotation.

4. Determine space

When looking at the charts in the design guide, it is clear that multiple thickness and width combinations can be used to produce the same torque. The inner diameter (ID) of the spring depends on the thickness, the life cycle and the required force. The outer diameter (OD) depends on the above, and the total length is taken as an additional consideration. The standard tolerance for ID and OD is ± 10%.

5. Calculate the total length

The total length of the constant torque spring shall take into account the actual number of turns of the spring on the output valve core plus at least enough material to maintain 1 / 2 turn on the spring when fully rotated. The formula for determining the length is as follows: l = π n (do + NT) + 10

6. Select end details

This end detail connects the spring to the output spool. We have many standard end details available. We have a complete tool and mold department that can create many designs that customers need.

7. Calculate the minimum spool spacing

The distance between the centers of the spool (dimension “s”) must be greater than the spring radius when completely wound on the storage spool, plus the spring radius when completely wound on the output spool.

8. Complete the design

Once the above criteria are reviewed and the constant torque projectile can be located or inferred from the design diagram.

Shenzhen Qianye Precision Metal Co., Ltd. was established in 2006 to supply high-quality stainless steel springs for many fields. Through continuous efforts, 19 patent certificates and 4 spring equipment software copyrights have been granted by the State Intellectual Property Office, and an enviable industry influence has been built. The company designs and manufactures a wide range of power springs, constant force springs, constant torsion springs, variable force springs and motor brush spring. Qianye works in close partnership with its customers in developing bespoke solutions to meet their individual needs. In order to offer better services, it has been continuously investing in production technology and supply chain. The company itself is a stainless steel raw material manufacturer. Because of the support of raw materials, it is not subject to material restrictions when making spring products; special material requirements can be developed and manufactured; furthermore, the delivery time is greatly shortened. Quality is of the utmost importance and Qianye are certified to ISO9001, ISO14001 and national high-tech enterprise with a big emphasis on the training of its employees. Its spirit is “treat people with sincerity and create things with sincerity” to ensure it strives for excellence.