"We have been relying on Neugart and its gearboxes for years because of the excellent application advice, the high product quality and the optimally coordinated product range. In the case of our servo-clinch machine, we could not have used a better planetary gearbox."
B.Eng. (DH) Florian Unger | Head of Development | Eckold GmbH & Co. KG
Clinching — the joining technology of the future
Florian Unger is the Head of Development at Eckold GmbH & Co. KG in St. Andreasberg in the Harz region of Germany. He has been relying on Neugart gearbox technology for years. Mr. Unger explains, “The entire package is easy to adjust with this gearbox manufacturer. The diverse product range provides the right gearbox for every application. We have found the perfect gearbox for us here - compact, powerful, maintenance-free and at a fair price.”
Eckold GmbH & Co KG is a medium-sized company with a history going back over 80 years. As a manufacturer of special-purpose machines, the company specializes in joining and forming technology. The main focus is on clinching, stamping and semi-tubular punch riveting technology. Clinching in particular is close to the heart of the people from the Harz region. It was company owner Gerd-Jürgen Eckold who brought clinching technology onto the market nationwide in the 1980s. Today, clinching has become indispensable in the automobile industry, household appliances and air conditioning and ventilation technology, not to mention spot welding and riveting technology. This method is almost the only alternative when different materials such as sheets of steel and aluminum need to be joined together without ancillary parts.
Eckold started retrofitting and enhancing its pneumo-hydraulic clinching machines on electro-mechanical systems years ago. Both technologies now co-exist. However, there is also a clear trend towards electro-mechanical systems in this area.
For components with different individual or total thicknesses, it is almost always necessary to adjust the base thickness in order to positively influence the undercut and stem thickness formation. A complicated matrix change is needed when using pneumo-hydraulic systems because of the fixed cylinder stroke.
With an electro-mechanical system, due to the variability of the drive stroke the user is often no longer reliant on a matrix change, which is therefore more flexibly positioned in the electro-mechanical system. Other advantages clearly lie in automation and the implemented continuous quality monitoring, which can be controlled in the program.
In automotive applications, for example, the clinching pliers are mounted as a complete unit on an articulated robot and operate autonomously in the production lines. Confined spaces are the rule when doing this. It is all the more important to have a compact clinching unit in order reach areas of the body that are difficult to access.
With the parallel design of the gearbox and the planetary roller screw, Eckold's machines were extremely compact right from the start. A servo motor drives the planetary gearbox directly.
This is connected to the planetary roller screw via a belt, and generates an axial movement with a high degree of pressing force. The radial force resulting from the pre-tensioning of the belt must be absorbed by the bearing technology of the planetary gearbox that is used. The requirement of the OEM’s for more compact units and the need to reduce cycle times prompted Eckold to look for alternatives on the market.
A new gearbox undergoes a strict testing procedure at Eckold during qualification. Testing with 10 million strokes takes place in-house. If this test is passed, the clinching units are delivered to the OEM’s for field testing. In steps of 2.5 million strokes, the devices are returned to the factory and analyzed in detail. Only the components which pass this process 100% have a chance of making the short list.
Finally, after all tests had been completed a Neugart gearbox was chosen. The arguments for using this gearbox are noteworthy, and offer countless benefits compared to previously used gearbox technology. The Neugart gearbox has extremely high efficiency of around 98%. It is about 10mm shorter, lighter and reaches a performance data that is 5 to 10% higher. This gives the clinching machine two advantages: the weight reduction increases the controllability of the articulated robot and therefore also reduces the process times. On the other hand, the smart unit is even more compact. The Eckold clinching machine is therefore unrivaled on the market in this area.
It was just as important to the Eckold engineers for the gearbox not to have to be re-greased during the machine cycle, even though the components were operated on a robot arm in any spatial coordinates. The customer therefore receives a drive train which can generate an axial clinching force of up to 100 kN. In addition to the technical advantages, Neugart gearboxes are a more cost-effective solution in comparison to the previously used gearbox.
Proof of DIN ISO 9001 certification and listing with well-known OEM’s was the prerequisite for being validated as a supplier to Eckold.
No problems or failures have been registered since the implementation of the Neugart gearbox in the clinching systems. In fact, Eckold uses the outstanding application knowledge of the Neugart contacts in order to detect and remedy irregularities in the overall system. Last but not least, this is supported by the Neugart NCP layout software which is available free of charge to Neugart customers.
Each new application at Eckold is designed with this program and subsequently used as part of the technical documentation. After designing, the developers use the Neugart Tec Data Finder to automatically download their specific gearbox as a configured CAD model.
Even in the reforming and punching technology area, hydraulic and pneumo-hydraulic drives are being replaced with electromechanical drive trains. Eckold supports this market shift with their latest machine types. One challenge for the future will be the option of joining a wide range of new materials using clinching elements. Maintaining machinery with long service lives will continue to be an important criterion for gearbox selection within the industry. All this presents new challenges for the components that are used. Because of the positive experience the company has had, Eckold is highly motivated to strengthen its collaboration with Neugart.
Clinching, also known as press-joining, is an innovative and proven technique for joining metal sheets and profiles. The permanent joints are exclusively created on the basis of local cold reforming, without additional or ancillary joining components. The main feature of this joining method is that the form-fitting joint is created from the material of the sheets that are being connected.
Because of this, the parts that being joined together can have either the same or different sheet thicknesses and even be made from the same or different materials.