When ballscrews develop super strength

The ability to use our hands is hugely important. They are involved in practically everything we do – from brushing our teeth in the morning and exhausting work during the day to putting our tired children to bed at night. Impaired hand function can therefore have serious consequences at work as well as at home. The mission of an enthusiastic technology and development company from Sweden is to manufacture bionic, power-generating products for people with reduced muscle strength or for additional strength requirements. The goal of finding the latest revolutionary innovation for the perfect drive solution has led Bioservo Technologies AB to Eichenberger.

Ironhand® combines medical know-how, robotics and computer technology. The Swiss thread specialist now breathes life into this magical hand with a lot of passion for the perfect movement.

Listening is the path to success

For the thread expert from Burg, Switzerland, exotic materials and dimensions or thread shapes outside the norm are welcome challenges. Eichenberger’s designers listen to customers and take note of their requests. An advisory, solution-orientated dialogue follows, during which answers are sought and found. The customers’ competitive and successful innovations and the inspired discussions associated with these are Eichenberger’s driving force for new developments. According to the motto: Quality begins with focus on our customers and ends with their satisfaction.

Quality of life, thanks to Ironhand
Weak hands can result in numerous challenges for people working on tasks that require a lot of gripping. Pain or lack of strength can lead to sickness-related absences. In critical situations, tasks may even have to be re-defined (re-training). This may affect the overall company as well as the physical and mental health of the individual. By providing tools, people can master their daily tasks again and/or return to their work. This means companies lose fewer qualified employees with key competencies, and individuals remain integrated in the world of work.

Ironhand is based on Soft Extra Muscle technology and was launched in 2019. The modular system consists of a glove covering five fingers, and a drive system. Pressure sensors integrated in the power hand control servomotors in the device. This provides the wearer with particularly strong grip.

One step ahead with the right technology partner
Eichenberger Gewinde AG boldly uses exotic materials, thread shapes and dimensions outside the norm. Unusual geometries, the company’s own interfaces, special materials and hardening procedures offer impressive extras. Where would you get a ballscrew with the measurements of 9.3 x 2.125 mm, for example? Only from Eichenberger! The tools required for this are made by the company itself. In this way, the thread specialist guarantees short time-to-market for application-optimised products with top precision and cost-effectiveness. In co-operation with Bioservo, Eichenberger has developed the perfect thread drive solution for Ironhand. Bioservo is a globally leading company in the area of soft exoskeletons and motor support focusing on the hand and other upper body extremities. The Bioservo team had the idea of developing a glove contributing to the prevention of stress-related injuries, to rehabilitation and to supporting people with their daily tasks at home or at work.

Super strength made easy thanks to ballscrews

Ironhand consists of a lightweight glove with a wearable control unit that is carried as a backpack. It is able to increase the user’s gripping strength by up to 80 N within milliseconds. The key components of this kit are five electrically powered, cold-rolled ballscrews by Eichenberger. It is these ballscrews that convert the rotational movements of the small servomotors into linear motion. Impressive efficiency of more than 94% guarantees perfect drive power.
The function of Ironhand is similar to that of our hands. A hand movement is usually initiated by the muscles in the forearm. Those muscles pull on the tendons that are attached to the five fingers. Ironhand works in the same way: The pressure-sensitive sensors in the fingertips of the glove recognise when the user grasps an object. A microcomputer calculates the required power. Servomotors drive five intricate ballscrews of 5 x 2 mm (Ø 5 mm, pitch 2 mm). They are connected with the fingers of the glove by thin wires. These fine connections move the fingers, and the additional strength is created by the slimline glove. The higher the pressure on the sensors, the more power the glove delivers. So Ironhand recognises how the user grasps an object and intuitively and automatically adapts the gripping movement.

Ironhand consists of a lightweight glove with a wearable control unit that is carried as a backpack.

Standard ballscrew or would you like a little extra?

Restricted assembly space with heavy loads is a frequent challenge. Silent movements within limited space are required. This is how Bioservo describes the requirements for the mechanical drive elements in the specifications. High positioning accuracies must be accomplished when trying to achieve the smallest lifts and high dynamics, when in constant use. We focus on safety and reliability. Maintenance intervals, service life and, not least, cost also play important roles.
Products with similar dimensions or quality perform better than expected at Eichenberger Gewinde AG. Using individual designs or special manufacturing processes, the thread specialist adapts its products to the application in question and makes the impossible possible. This is how products that bring customers’ innovations to the forefront of the market are created. The cold-formed, inductively hardened Ironhand ballscrews, with the dimensions of 5 x 2 mm, combine speed, precision and minimum spatial conditions. Additionally, the perfect pitch ratio of the screw increases movement efficiency. “The five Swiss heroes”, with three clever single-thread returns integrated in the nut, stand out with their low weight and increase the cost-effectiveness of the overall solution.

Highest carrying capacity, power density and extreme dynamics

Designers are regularly faced with the challenge of finding the right drive solution to implement linear movements. The complexity of systems is increased by technological advances. Ballscrews are one of the most commonly used drive systems in many areas. Rolled thread drives have become established in the field of linear motion: there is no alternative to cold-formed screws. The advantages of this drive system are its high level of effectiveness and energy efficiency. Eichenberger’s screw technology, thread rolling (cold-forming of the surface of round components), combines the highest carrying capacity and power density with extreme dynamics and remarkable precision with maximum performance. There is huge potential in industrial automation, robotics and medical technology. Unexpected development options can also be found in a wide range of industry as well as research applications for semiconductors, photovoltaic systems, vacuum valves etc. This is how Eichenberger Gewinde AG covers a wide industry spectrum from mechanical engineering, medical equipment, electrical engineering and automotive to space travel. The various fields of application are very different but there are still many similarities. All areas are characterised by the constantly increasing quality requirements, the trend towards higher intelligence and the search for cost-effective overall solutions.

Eichenberger’s screw technology, thread rolling (cold-forming of the surface of round components), combines the highest carrying capacity and power density with extreme dynamics and remarkable precision with maximum performance.

What makes the ballscrew Carry so resilient and the ideal functional element for this application? Thread rolling creates very precise geometries with a high surface quality. During the usual manufacturing processes for threads, such as milling and turning, the material is cut. This has the disadvantage that they interrupt the grain orientation of the steel. On the other hand, there is thread rolling. In this non-cutting process longitudinal fibres are not cut but diverted. At the same time, the surface profile is hardened. This “smooth-rolled surface” offers almost no scope for contamination. This is critical for a long service life and it also enables quiet rolling of the balls. This cold forming also leads to very good roughness values (~ Rz 1.0) on the edges of the threads and in the base radius.

SEM technology

The patented SEM technology concept exceeds the state-of-the-art. To support the wearer, data is collected and analysed to identify and assess grip-intensive application cases with a high ergonomic risk. The implemented “Intent Detection Logic” only activates support if the wearer initiates the movement with natural and intuitive force. This is achieved using sensors that capture the user’s action. The motors are actuated automatically and increase the wearer’s power. The drives respond immediately and in a natural way to make the intended movement easier. This means that Ironhand calculates how the user grasps an object. The more difficult the gripping movement, the more power is provided.