New Safety Concept Through Clamping

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-05-24 11:12

Safety first: Legislators require a minimum standard for the safety of people who work directly with machines. A whole range of safety measures can be taken to comply with the Machinery Directive. EN ISO 12100 specifies this requirement in a three-step process: First, a safe construction must always be selected; if this is not possible, technical protective measures must be taken. Only if these measures are also not feasible must user information be provided in the form of instructions.

Determine the performance level exactly

For a safe construction, the Ratio-Clamp from Hänchen as a holding system can secure the load in the event of an accident. For example, a load must never lead to a movement that is dangerous to life and limb. The exact requirements are determined on the basis of the performance level (PLr). With it, the machine manufacturer has to work out the danger that a machine can pose. The PLr describes which contribution to risk reduction is made by the safe control parts.

To enable the customer to use the RC as a relevant component for the calculation of his PLr, Hänchen has carried out long-term tests with the Ratio-Clamp. The components were loaded around the clock over several months. The result: Now Hänchen can give its customers a realistic B10D value for the construction instead of the very low standard values recommended in EN ISO 13849. The newly determined, significantly higher B10D values depend on the component size.

Seminar tip

The seminar "Basic knowledge of the Machinery Directive" gives manufacturers and operators the necessary basic knowledge about current developments and requirements in product safety.

The manufacturer of a safety component such as the clamping unit can only specify a B10D value. It can now be used to calculate the associated MTTF value (Mean Time To Failure) depending on the number of cycles. On this basis, the PL is calculated, for example, by the DGUV calculation software. The DGUV Test (German Statutory Accident Insurance) mark is a voluntary test mark. This confirms that the product meets the defined health and safety requirements. Through the redundant use of different systems, the security level can be adapted to the given requirements.

The Ratio-Clamp can be used as part of the machine functionality to hold loads safely in axes under gravity. The decisive factor is the design principle, by which a rod is held for an unlimited period of time in a de-energized state. The RC works mechanically according to the principle of frictional engagement: the force stored in the screw disc springs is deflected via a cone and clamps the rod by means of friction. If the release pressure drops, the force stored in the springs is released and clamps the rod. This secures the load and the ratio clamp can take over the load. Due to the hydraulic release pressure, the locking piston is moved against the spring force and thus unlocks the clamping unit. The bar can now be moved in both directions again.

The Ratio-Clamp type RCH with the DGUV Test certification can be used as a safety component for vertical loads. For this, the DGUV prescribes safety factor two. The nominal holding force of the RCH is therefore twice as high as the permissible load that it can carry. Of course, this type is also provided with a CE conformity certificate as a safety component.

Machine safety user meeting

Machine safety is an important issue: the correct standards must be taken into account and the requirements of the Machinery Directive must be complied with. The machine safety user meeting supports developers and designers to ensure the functional safety of machines and systems.

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