Human interaction is required for the alternating loading and unloading of a test system: once one of the two electronically driven feed units is fully extended, the operator removes the I.O.-tested door trim element and stacks it. With the other hand, he places the untested element in the pick-up device, scans the cable harnesses and connects them to the electrical contacts of the test station. Only when he has completely left the area does the 1.5 m/s feeding unit automatically enter the system. The test routine starts, and eleven seconds later the second material feeder moves out. Task steps that are constantly repeated.

With this test system, the system operator knows that the automated slide-in units will not start moving while they are being unloaded or loaded or while the system is in test mode. A monitor shows the progress of the process and signals when the operator must leave the safety zone or is no longer permitted to enter this area from outside. If he fails to do so, an acoustic signal warns him. If he ignores the warning, the system immediately moves to a safe stop.

Hidden Safety

The safety laser scanner PSENscan from Pilz ensures productive surface monitoring on the automated inspection system of the Brainware machine: the inspection process has been reduced by a third of the time.

© Brainware Solutions / Pilz

In terms of safety, however, the essentials are initially hidden from view: the compact system, measuring approximately 2 m x 4 m on the ground and 2 m in height, stands freely in the room, with no protective fences or enclosures of any kind. The only visible signs of room surveillance are two mirror columns, which form a rectangle at a distance of 2 m in extension of the loading front. However, light curtains alone do not provide protection from behind.

Zero ppm (parts per million) is not only synonymous with zero error tolerance in the automotive industry. The company's testing systems must not be allowed to miss any faults, and not only during the quality check of door panels - door panels have different colors, different cover materials and are equipped with various switches, lighting units, loudspeakers, cable sets and much more. Systems from Brainware Solutions use 16 cameras, some of them high-resolution, to check around 50 features for presence, completeness, correct design and more in a single test run. Over 100 inspection features have already been realized in comparable projects.

A fast and economical inspection system cannot work without an intelligent and convenient operating concept that does away with disruptive safety fences or other protective devices that tend to hinder and separate. The requirements on the part of Brainware Solutions were therefore clearly formulated: Operators should have unhindered access to both slide-in units, be able to load and unload them safely and not be within reach when they are being extended and retracted as scheduled.

Safety laser scanner protects processes

The implemented solution consists of a pair of safety light grids, whose transmitters and receivers are each installed at one of the front corners of the test system and form a rectangle with the two mirror columns in front of them. This area is defined as a safety zone with rear step protection. In addition, a 'PSENscan' safety laser scanner from Pilz is mounted centrally below the slide-in units, providing two-dimensional area monitoring with an opening angle of 275° and a protective field range of up to 5.5 m. The safety laser scanner is used for stationary and mobile area guarding as well as access monitoring and can be connected in series depending on requirements.

The safety laser scanner permanently scans the defined safety zone on the automatic testing machine. In conjunction with the safe small controller 'PNOZmulti 2' installed in the control cabinet, this safety solution not only detects the operating personnel, but also their direction of movement. If the safety light curtain detects that a person has passed through after leaving the so-called rear access area, the small controller knows that no one is still in the protective field - i.e. the safe zone. However, only when the operator has completely left not only the protective field but also the two warning fields in front of it (the warning zones) is an automatic acknowledgement process generated: the previously equipped slide-in unit retracts and the operator is definitely at a safe distance.

The author: Tobias Leska is a sales engineer at Pilz in Ostfildern.

© Mushroom

If the test process is in progress and the slide-in module to be tested is closed, the protective field remains deactivated. Operators can stand safely in front of the machine and change the door modules to be tested. If one of the two feed units is about to be extended, a monitor announces the activation of the protective field, which must then be left quickly if the system is not to be stopped.

The two upstream warning fields also serve to prevent access from outside into the activated safety area. In principle, extension is prevented as long as an operator remains in the safety zone.