An oxy-fuel system for supplying a torch with a fuel gas stored under pressure in a container includes the following components: (a) an upstream fuel gas supply line between the container and the torch; (b) a demand valve arranged in the upstream fuel gas supply line; (c) the torch connected to an oxygen supply line. The torch includes a venturi nozzle adapted to generate in the upstream fuel gas supply line a negative pressure P.sub.negative of at least 0.3 bar relative to atmospheric pressure in operating condition, and the demand valve is vacuum-controlled and configured to have a pressure setpoint to open the demand valve, the pressure setpoint being negative relative to atmospheric pressure and equal or less negative than P.sub.negative.

A method for producing workpiece parts from a plate-shaped workpiece in a processing machine or laser processing machine includes positioning and holding the workpiece on a workpiece support by clamping devices. A plurality of workpiece parts are cut out of the workpiece with a process beam. The process beam is moved relative to the workpiece support by a processing head and/or the workpiece is moved relative to the workpiece support by the clamping devices. A cutting process for processing the workpiece to produce the workpiece parts is interrupted at least once by a relaxation step for the workpiece. During the relaxation step at least one clamping device is released to relax the workpiece. The at least one clamping device is closed following the relaxation and before continuing the cutting process. A data processing program and a processing machine for producing the workpiece parts are also provided.

A laser working machine includes a first slot provided at another end portion of a first body. In the first slot, either one of a first shielding plate and a first light transmissive plate is selectively insertable in a sealed manner. The first shielding plate is configured to block a first optical path. The first light transmissive plate has a first optical path hole through which the first optical path and a second optical path are connectable. The laser working machine includes a second slot provided at a second body end portion of a second body. In the second slot, either one of a second shielding plate and a second light transmissive plate is selectively insertable in a sealed manner. The second shielding plate is configured to block the second optical path. The second light transmissive plate has a second optical path hole.

A laser working machine includes a first slot provided at another end portion of a first body. In the first slot, either one of a first shielding plate and a first light transmissive plate is selectively insertable in a sealed manner. The first shielding plate is configured to block a first optical path. The first light transmissive plate has a first optical path hole through which the first optical path and a second optical path are connectable. The laser working machine includes a second slot provided at a second body end portion of a second body. In the second slot, either one of a second shielding plate and a second light transmissive plate is selectively insertable in a sealed manner. The second shielding plate is configured to block the second optical path. The second light transmissive plate has a second optical path hole.