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Automated screwdriving with cobots

| Screwdriving technology

DEPRAG presents lightweight SFM for lightweight robots

The increasing diversity of products, smaller batch numbers and shorter product life cycles all present new challenges for assembly. Automated processing steps are often uneconomical for small or medium-sized companies as they involve high costs. However, with the development of cobots over the last few years, hopes have been raised. Manual assembly tasks can now be technically supported at a reasonable cost, thus utilising previously inaccessible automation potentials.

Entirely new possibilities have opened up for assembly through the use of cobots. Low investment costs enable the fast, economical implementation of applications: Robots with a low load capacity are significantly more affordable and the total size of the system or machine is substantially reduced when using smaller robots. Applications of this kind require assembly tools of an equivalently light weight. DEPRAG SCHULZ GMBH u. CO. KG, renowned for their decades of experience in screwdriving technology, have developed an innovative lightweight Screwdriving Function Module which fulfils all the specifications for integration with a cobot. It is irrelevant for the screwdriver which manufacturer the robot is from. The DEPRAG screwdriver can be attached to a Kuka, Universal Robots (UR), Stäubli, ABB, Fanuc, Yaskawa and other common robots.


Screwdriving function module in and for lightweight construction

The lightweight SFM scores particularly highly with its low weight of just approx. 1.5 kg with a maximum torque of 4.2 Nm. This already includes mouthpiece and nosepiece ensuring reliable assembly of the screw. The use of lightweight materials is indispensable in attaining this low weight. Whether components are made of composite materials such as carbon, aluminium parts from a 3D printer or light synthetic parts – each gram counts.

Additive production processes can even be used, for example, to cost-effectively manufacture the required screwdriver adaptor using aluminium, or the mouthpiece using hardened tool steel. Carbon fibre tubes or sheets are lightweight but can bear heavy loads. Integrated robot-specific attachments are also an option: Consisting of an aluminium body combined with a carbon fibre sheet – they eliminate the need for an additional adaptor.

Even in the construction of the Screwdriving Function Module, fasteners made from aluminium and bonded components are used to reduce weight even further. With all these weight-optimised elements, the DEPRAG lightweight SFM is highly suitable for robots with low load capacities and is also designed to withstand the highest loads. Cobot and screwdriver form a perfect assembly unit. In practice, the term HRC screwdriver is often used.

Cobot and screwdriver - an unbeatable combination

If the function module is equipped with DEPRAG spindle screwdrivers, a wide range of possibilities is opened up with seamless processing data acquisition and the creation of up to 1000 screwdriving programs. This clears the path for production which takes all elements of reliable screwdriving assembly into consideration – even for safety-related fasteners. In combination with a DEPRAG screw feeding system, this single source solution supplies a comprehensively tested screwdriving unit. Cobots with screwdrivers are an unbeatable combination.

The lightweight SFM can be used in conjunction with any DEPRAG feeding system: They efficiently and accurately supply fasteners in the desired cycle time. Precisely timed supply is an essential element for the productivity and reliability of assembly processes. Integration is particularly simple and convenient. The range includes step feeders, sword feeders, vibratory spiral feeders, as well as screw presenters. Fasteners either with or without a head can be assembled using the lightweight SFM.


Process reliability thanks to optional additional functions

The Screwdriving Function Module itself can also be equipped with optional additional features. A screw depth sensor, for example, can be used as a shut-off parameter for assembly to depth with adjustment screws. This results in greater process reliability for the relevant production step.

Process reliability is further increased by utilising the most appropriate tightening procedure. Direct screw assemblies often result in fluctuations, for example due to varying screw or hole geometries, the structure of the component material, altering surface qualities, spring-loaded elements or seating conditions. According to the application needs and changing framework conditions, the most ideal procedure for the application can be realised with the screwdriving system: Choose from torque controlled or angle controlled screw procedures, friction value procedures or Clamp Force Control to detect seating point and therefore improve constancy of the pre-load force.

The lightweight SFM also provides a universal, flexible concept in regards to Industry 4.0 and system communications. The smart tool is supported by the software solution DEPRAG Cockpit and is particularly suited for use in the networked, digital factory. The software collates all assembly-related production data and presents it in a structured, user-friendly format. All screwdriving tasks can be parameterised, visualised, documented, analysed and optimised. The goal: huge cost and time savings in assembly.

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