Constant force spring drum

Types of constant force spring drum

Constant force spring drums are usually categorized into types based on the shape of the spring and the materials from which the drum is built. Application differences also impact the type of design one can find.

Following are some of the common types, in no particular order:

Cylindrical Constant Force Spring Drums

This is the most common type of constant force spring drum. A cylindrical shape provides a uniform release of force as the spring unwinds. Such designs are thus perfect for long-term applications where a steady and consistent force is essential.

Flat Springs

Apart from cylindrical springs, flat constant force springs are also widely used. Such springs are usually made from flat metal strips. These are coiled onto a drum. As the spring unwinds, it provides a constant force.

Flat films are often used in applications where space is limited. Examples of such applications go into the making of Spring-Loaded Axles and Equipment Coves.

Conical Shape Drums

Unlike the commonly used cylindrical constant force spring drums, the conical constant force spring drums are tapered on either end or both ends. The force delivery pattern on these drums is different and not so linear. Also, it might not be as uniform as on cylindrical or flat drums. Nevertheless, conical shape drums provide a variable force.

This means that the spring tension increases or decreases as the spring is fully or partially unwound. Such a design is excellent for shock absorbers and other automotive applications where changing force is required.

Industrial applications of constant force spring drum

Automotive Systems

Constant force pressure springs find extensive usage in the automotive world. For example, one will find them in trunk lid dampers and seat reclining mechanisms. The springs control noise, vibration, and even inconsistency in the vehicle's operational critical drives.

Aerospace Engineering

Strength, reliability, and weight concerns are mandatory when dealing with components for the aerospace industry. Constant force spring drums offer all of this in their performance. Accordingly, they are used in cargo bay doors and even engine components. Their reliability in such extreme conditions makes them worth having in this industry.

Consumer Goods

One may come across these springs in everyday consumer products. Common examples are retractable tape rules and window shades. In these cases, the springs do enhance simple mechanisms. What is more, they ensure smooth and reliable operation at the end of the day.

Industrial Machinery

Constant force spring drums are used to control tension in belts and cables. This, after all, ensures machines run efficiently and smoothly without any problem. The most common places of usage of constant force spring drums in industrial machines include conveyors and robotic arms.

Medical Devices

The requirements of medical devices are the same as those of the aerospace industry. It also needs reliable and high-performance components. So, it is no surprise that constant force spring drums are found in surgical equipment, dosage pumps, and medical monitoring devices. They provide the required precision.

Defense and Military Equipment

In the defense and military industries, constant force spring drums are used in equipment like bulletproof vests, parachutes, and other rescue mechanisms. The springs, as seen above, not only improve efficiency but also ensure the safety and reliability of such critical components.

Product specifications and features of constant force spring drum

Technical Specifications Constant Force Spring Drum

• Material: Constant force spring drums are usually made of stainless steel, high-carbon steel, or titanium alloy, depending on the application. Stainless steel is corrosion-resistant and excellent for marine and medical equipment. High-carbon steel is for mechanical applications where wear resistance and long fatigue life are required. Titanium alloy goes for high-strength, low-weight applications. The aerospace and medical industries love it.
• Spring Width: The constant force spring width varies widely. It can go from 5 mm to 100 mm. The wider the spring, the greater the force exerted. The application in question usually determines the width.
• Spring Thickness: The thickness of the constant force spring varies widely too. It can go from 0.2 mm to 1.5 mm. The thicker the spring, the greater the load it can bear. Once again, this is only true when the tension is applied.

How to install constant force spring drum

• Tools Required: The tools needed for the installation will typically include a wrench set, screwdrivers, mounting brackets, measuring tape, and safety gear like gloves and goggles.
• Installation Steps: The first step of the installation process is, as it is always supposed to be, the preparation of the site. The mounting location of the constant force spring drum should be clean and free of any obstacles or debris.

Once the area has been cleared, the next step is to measure and align the drum. So, using the measuring tape, locate and mark the mounting points. The points have to be on the drum itself. Then, using the mounting brackets, secure the constant force spring drum in place.

With the constants force spring drum well secured in place, the next step is to attach the load or the application component to the spring. At one end of the spring, attach a load or the application component. Conversely, at the other end of the spring, attach a cable or hook.

Once everything is ready, the next step is to balance the spring tension. Do this by gradually applying load. This way, it ensures that the spring tension is evenly applied. It also does not allow one area to be overstressed.

Gradually pull on the spring until it is properly tensioned. This means that the load should be evenly distributed across the entire spring surface. Overstressing one area leads to premature wear or even damage to the constants force spring drum.

Finally, secure the system with appropriate hardware. Tighten all bolts, screws, and other fasteners to ensure the stability of the spring drum and load. Once installed, the constant force spring drum needs to be regularly inspected. Look for signs of wear and tear.

Maintenance and repair of constant force spring drum

• Maintenance Tips: Inspect the drum daily. Just take a look at it. Obtain an annual inspection checklist and inspect the spring core, force spring cable, rotating elements, and accessories and fasteners as often as required. In the case of a problem, just fix the drum.

Lubricate the spring at least weekly. Proper lubrication reduces friction and extends drum life. Just don't apply too much of it.

Clean the spring and the drum once every two weeks. Clear all debris and dirt from the work station. This reduces potential hazards for workers.

Check the tension of the constant force spring used at least once a month. Ensure it's within the required standard.

Examine the fasteners, anchors, and hardware at least once a month. Repair them as needed. Always replace broken hardware and equipment.

Replace worn dollies, rollers, and wheels once a quarter. It is for the best interest of all.

Repairs. No repairs should be attempted during maintenance. It is a no-go area. Repairs include making all the necessary adjustments, including readjusting the nip, which is a repair procedure. Don't forget to do it.

Worn-out drums shouldn't be used. If the drum is damaged or worn out, don't use it again. Get a new one.

Use safety devices or lanyards when necessary. Safety devices support or hold the spring drum in place. Always lanyard springs that have the potential to rise. Don't replace your safety devices with makeshifts or items that were never meant to serve as safety devices.

How to choose constant force spring drum

Several factors go into choosing the right constant force spring drum for any application. These factors include load capacity, mounting orientation, operational environment, and drum material.

• Load Capacity: First buyers need to choose a spring drum with load capacity equal to or greater than the required load weight of the application in which the spring drum will go. This load weight goes without saying, as it is always better to go for one with higher load capacities. Such drums will have lower stress and, therefore, greater longevity.
• Drum Size: The size of the constant force spring drum varies widely. It can range from a few centimeters to over a meter in diameter. The larger the drum, the more cable or ribbon it can store. Store a larger drum, and it will have lower tension. Basically, bigger springs are meant for bigger applications.
• Spring Material: Different materials have different tensile strengths and fatigue lives. The most common materials from which the drums are made are stainless steel, high-carbon steel, and titanium alloy.
• Operating Conditions: Operating conditions refer to the environment in which the spring will be working. These conditions can change with time. They can change subtly or drastically, and they affect the choice of the drum. For instance, if the working environment is humid, it is better to go for a stainless-steel drum. Stainless steel is corrosion-resistant, after all. Similarly, if there is a chance of frequent temperature changes, choose a materials drum that can withstand thermal shocks.
• Mounting Configuration: Different applications require different mounting configurations. Some applications require lateral mounting, while others require axial mounting. Understanding the application in question helps a lot in making the right decision.
• Spring Design: The design of the spring determines how much energy will be stored in the spring. Different force spring designs provide different energy storage capacities. Constant force spring design goes for longer life cycles. For example, a cylindrical spring provides a uniform release of energy all through its unwinding process.

Q & A

What is a Constant Force Spring Drum?

A constant force spring drum is a mechanical device used to store and release a constant amount of energy over time through a spring mechanism. Depending on their design, they smooth the motion as they release a constant force. This makes loads carried by the springs constant. By using them, mechanical shock is greatly reduced.

What are the Common Uses of a Constant Force Spring Drum?

The common uses of a constant force spring drum constantly release force to achieve the same result. Common examples of places where they can be found include automatic window shutters, measuring tapes, clutch plates, and projectiles.

Which Materials are Usually Used to Make Spring Drums?

Various materials are used to make constant force spring drums. Each material has its unique characteristic and advantage.

• For instance, high-carbon steels have high tensile strength and hardness. They also give the spring a better shape, something low carbon steel cannot do due to their composition. The high tensile and hardness allow the use of practical shapes that can carry more current without losing all its functionality.
• Unfortunately, high carbon steel has one major drawback. It is susceptible to corrosion. To overcome this drawback, manufacturers now coat the high-carbon steel with other non-corrosive materials. These materials include brass or chrome.
• Other manufacturers use titanium to make the constant force spring drum. Titanium is excellent when it comes to strength-to-weight ratio. It is also resistant to corrosion. Thus, it is used in all kinds of aerospace, military, and medical applications. You do not want to use titanium on your constant force spring drum because of its high cost.
• Some manufacturers even use alloys in making the constant force spring drum. Also, they use non-ferrous materials like copper or bronze. Alloys and non-ferrous materials are used for electromagnetic applications. They are also used around electrical devices. They will not interfere with the devices, after all.

What factors to consider when choosing a Constant Force Spring Drum?

Many buyers consider factors like load capacity, operating temperature, and environment when choosing a constant force spring drum. They also consider the corrosion resistance of the materials used to make the drum.

They will normally select a spring and housing material that is compatible with the working conditions, especially if there is a risk of the drums coming into contact with chemicals. They will also select the correct spring width and thickness. These two should be compatible with each other.

More importantly, the drum and the load should never be in contact with each other at any time. So, it is important to select a constant force spring that has a similar thickness to that of the load. Lastly, they consider the install space constraints. If the space is limited, they go for flat constant force springs.