Laser scanners ensuring safe human robot collaboration

With the help of
safety laser scanners from the microScan3 product family, as well as the Flexi
Soft safety controller, DESMA ensures the safe operation of a robot on an
injection moulding machine. The electro-sensitive protective devices allow a
person ergonomic access to the machine for
process-orientated material staging and removal. The robot automatically picks
up the raw material provided as soon as the safety perimeter is clear and
dispenses the processed silicone and rubber parts. At the same time, the safety
laser scanners are especially economical on
space and therefore, do not impede the process.

safety concept for the robot on the DESMA injection moulding machine was developed in close collaboration between
application consultation personnel at SICK and specialist departments at DESMA.
It combines a horizontal 275¡ protective field used to monitor the hazardous
area in front of the robot with vertical protective fields for hazardous point
protection in the work area. When a person approaches the robot, a horizontal
safety laser scanner detects this at an early stage, slowing down the robot in
a controlled manner to avert any danger
from its movement. It is now possible to significantly reduce the necessary
safety distance between the vertically monitoring microScan3 and the hazardous
movements of the robot, and therefore also minimise
the total space required for the machine and its safety technology.

further microScan3 monitors the robot’s delivery table. If the machine operator
needs to change a tool, for example, and in doing so stands on the table and inside
the monitored area, the safety laser scanner will detect this, and the robot will be prevented from starting. The entire safety-related application
can, therefore, be operated with automated restart without manual restart
interlock. Since the safety technology follows the workflows autonomously,
workers no longer perceive it as a nuisance since they are not required to interact with the machinery by pressing a restart
switch. The required logic for this and integration of other safety
components, such as the emergency switching off button, is provided in the
Flexi Soft safety controller. The collectively developed protection concept
offers the highest levels of performance and availability for machines processing
silicone and rubber at DESMA. This is largely
due to the innovative safeHDDM scanning technology of the microScan3.

DESMA: Experts in injection moulding

Desma Elastomertechnik GmbH in Fridingen is a premium system-based solution for
a whole host of industries, operating through individual turnkey systems for
the production of technical rubber and silicone moulded articles. The company
offers injection moulding technology, tool manufacturing, and automation
engineering from a single source, with the injection moulding machines fulfilling
customer and industry-specific requirements and enabling safe processes. This facilitates the highly profitable
production of rubber and silicone moulded parts used in vehicles, ships, power
supply plants, or medical devices.

Human-robot cooperation for
automated material transportation and removal

technologies are a key feature of DESMA injection moulding machines. This
outlook also applies to their production methods, which produce technically and
economically efficient rubber and silicone
processes. An area for improving productivity is the work environment where
humans and robots share space at different times. This human-robot
collaboration (HRC) enables highly optimised
workflows and improves plant availability, productivity and economic
efficiency. That’s why DESMA has developed this cooperative workspace for its
injection moulding machines, which sees a worker supply blanks and the robot
act as a production assistant by taking hold of them and inserting them into
the machine. Once the blanks have been machined,
the robot removes them, gives them to the operator to take away, and inserts
the next set of blanks. The process sequence highlights how important it is for
workers to have unrestricted access to the machines. Protective fences or other
mechanical devices around the HRC workspace will cease to exist at DESMA.

Horizontal and vertical protection
with microScan3 safety laser scanners

injection moulding machine manufacturer has found a solution for this robot
application through an electro-sensitive safety system, which eliminates the
risk of accidents for operators and grants them unrestricted access to the
machines. Connected to the Flexi Soft safety controller are a total of four
microScan3 safety laser scanners, two with horizontal and two with vertical
pairs of protective fields. Regarding
object resolution, these can be configured
in steps between 30 millimetres, hand detection, and 200 millimetres, body detection. This means that a single
microScan3 can work with several
protective fields in various resolutions. The integration of these compact and
reliable devices is incredibly simple. Mechanically, it involves a shock and
vibration-resistant mounting system, and electronically, the devices are installed via an eight-pin M12 standard
connector. The protective fields to be monitored have a scanning range of up to
5.5 metres and can be easily and directly defined in the machine layout
using the Safety Designer software and a laptop. This configuration via USB can
then be saved in the safety laser
scanner. While in operation, the microScan3 multi-colour display shows the operational
status of the system, and additional information can be called up as cleartext
by using the pushbuttons on the control panel.

technological highlight of the microScan3 safety laser scanners, which meets
performance Level D in accordance with
EN ISO 13849 and SIL2 in accordance
with IEC 62061 is their safeHDDM scanning technology (short for
high definition distance measurement). This high-resolution digital process for
safety-related time and distance measurement
sends out more than 100 times as many laser pulses as other time-of-flight
measurement systems.

Unrivalled and stable measured
values for enhanced productivity

multi-pulse process in conjunction with focused, digitalised evaluation enables much more stable measured values to be generated and also reliably detects
predefined minimum remission values of 1.8 percent, without them being masked by interference signals. The
reliable evaluation methods of this scanning technology guarantee maximum
availability in the presence of dazzle, dust, or other environmental
influences, for example.

Codified pulses prevent mutual

laser pulse time coding of each safety
laser scanner is particularly crucial if many devices are being operated at the
same time and within proximity of one
another. To protect the robot on the injection moulding
machine, a total of four microScan3 safety laser scanners are installed at the robot table at a height of around 200 millimetres. Two
of these generate vertical protective fields, which meet at a 90¡ angle to
provide access protection; the third and fourth safety laser scanners are installed horizontally, on and in front of
the robot table, to provide area protection. Although the safety laser scanners
could be subject to mutual interference, this issue does not arise for the
microScan3. The laser pulses of each device are
coded by a time delay of a few nanoseconds while an integrated random generator additionally modifies their sequence.
Therefore, the occurrence of two identically encoded scanner sequences – and
with it, the danger of mutual
interference – is about as likely as a jackpot win on the lottery.Other sensors and sensor systems that use laser LEDs
as light sources do not impair the safety function and availability of this new
scanner generation.

Increased immunity to dazzle, dust, and deposit formation

HRC applications are used in standard production, mounting, and
logistics environments. The microScan3 safety laser scanners as the HRC
monitoring solution for the DESMA injection moulding machine must be able to cope with the anticipated ambient
conditions. With their safeHDDM scanning technology, they achieve an unrivalled
level of ambient light immunity of up to 40,000 lux. They are therefore
practically immune to dazzle, regardless of whether it is from bright sunlight,
high-frequency, artificial ambient lighting or light sources, or reflections
shining directly into the optics. What’s more, the evaluation by safeHDDM
ensures that the reliability of the detection and protective functions are not impaired
either by dust particles in the environment or by deposit formation on the
optical interface of the sensors. Furthermore, the microScan3 safety laser scanner features a parabolically curved front screen. This deflects reflections that arrive outside of the optical path of the laser pulses and their remissions into an optical trap, away from the receiver element in the device. It also increases the immunity to dust and deposit formation and
the mobility of the robot on the injection moulding machine.

Extensive expertise in designing safe robot applications

The microScan3 product family
has brought about a change in the active scanning
safety laser scanner market, delivering benefits concerning safe and highly available human-robot interaction in particular.
The microScan3, as well as the Flexi Soft safety controller belong to a range
of sensors and controllers that has developed along with the requirements of
safe robot applications over the decades. Safety solutions based on various
technologies are becoming more and more intelligent and are constantly making
possible new HRC applications with increasingly demanding requirements. When it
came to choosing SICK as its implementation partner for this HRC application,
the decisive factor for DESMA was SICK’s broad portfolio of product and system
solutions. SICK was also able to offer a high level of consultation expertise
in the field of safety technology, as well as comprehensive services with respect to safety concepts, according to
Heiko Wolters, Team Leader in Hardware Development at DESMA.

Written by Michael Sanchez, Field Sales, SICK Vertriebs-GmbH, Düsseldorf

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