3 Fundamentals of press design

Press safety and certification
present, but comprises an index which makes reference to the various
sections by means of an identification number.
In the case of a hazard analysis, safety is monitored over each phase
of the machine’s life, from assembly through to commissioning, utilization,
repair and final scrapping. Protective measures must apply equally
to machine operators, set-up and maintenance staff. Depending on the
risk, safety must also be guaranteed in case of machine malfunctions. As,
for example, the failure of a brake valve and thus the unchecked movement
of the slide could lead to serious injury, dynamically monitored
press safety valves must be used unless it is possible to provide an equivalent
degree of safety by keeping safety devices closed. The monitored
valves are redundant (double valves) and, depending on the requirements
of their respective functions, they are self-monitoring. This
means that despite a brake valve failure, the “braking” function is still
performed, accompanied by a message indicating whether the two
valves have operated correctly or not. A positive “function OK” signal is
used for self-monitoring of the signalling module (cf. Sect. 3.5).
In analysing potential hazards, the manufacturer must also consider
“foreseeable unusual situations”, e.g. surprise situations of the type
previously mentioned. The operating instructions must accordingly
include a statement on machine utilization in accordance with the
intended purpose of the machine, and also prohibit any foreseeable cases
of violation, for example operation of the press while observers are
located behind the closed protective gear in order to observe the
machine operation. Indications of possible violation of operating regulations
are often only possible after observation of operating, set-up
and maintenance staff. The results of the hazard analysis are reflected
in the design of protective gear, remarks relating to residual risk at the
machine and in the operating instruction manual. Thus, they are made
known to the machine user.
3.6.5 Measures to be undertaken by the user
When purchasing a machine, the user must establish by means of a
contractual agreement the identity of the manufacturer as defined by
the ECMD and the position with regard to items of equipment provided
by the user. When purchasing machines, whether new or used, from
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
115