Safety without the need for protective fences

Aug 24, 2017

With the help of safety laser scanners from the microScan3 product family as well as a Flexi Soft safety controller, DESMA guarantees the safe operation of a robot on an injection molding machine. The electro-sensitive protective devices allow ergonomic access to the machine for the purposes of 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.  


The safety concept for the robot on the DESMA injection molding machine was developed in close collaboration between application consultation personnel at SICK and the responsible 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 of 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 so as to avert any possible danger from its movement. As a result, it has been possible to significantly reduce the necessary safety distance between the vertically monitoring microScan3 and the hazardous movements of the robot - and therefore also to minimize the total space required for the machine and its safety technology. A further microScan3 monitors the robot's delivery table. If the machine operator needs to change a tool, 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, i.e., without manual restart interlock. Since the safety technology follows the workflows entirely autonomously, workers no longer perceive it as a nuisance. The required logic for this as well as the 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 - thanks in no small part to the innovative safeHDDM™ scanning technology of the microScan3 - the highest levels of performance and availability for the machines processing silicone and rubber at DESMA.


Human-robot cooperation for automated material transportation and removal

Premium system-based solutions for a whole host of industries - Klöckner Desma Elastomertechnik GmbH in Fridingen realizes this ambition through individual turnkey system solutions for the production of technical rubber and silicone molded articles.

Forward-thinking technologies are a key feature of DESMA injection molding machines. The same applies to production methods for technically and economically efficient rubber and silicone processing.  

One option for improving productivity are work scenarios in which humans and automated machines share the same workspace but work at different times. This human-robot collaboration enables highly optimized workflows and improves plant availability and productivity as well as economic efficiency.

Desma_absicherung_boden Horizontal and vertical protection with microScan3 safety laser scanners.

That is why DESMA has developed this cooperative workspace for its injection molding 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 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 workspace will cease to exist at DESMA.


Horizontal and vertical protection with microScan3 safety laser scanners

The injection molding machine manufacturer has found a solution for this robot application with 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 - two with horizontal and two with vertical pairs of protective fields. In terms of object resolution, these can be configured in steps between 30 millimeters, hand detection, and 200 millimeters, body detection - this means that a single microScan3 is able to 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 meters 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-color display shows the operational status of the system - additional information can be called up as cleartext by using the pushbuttons on the control panel.  

The 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, which sends out more than 100 times as many laser pulses as other time-of-flight measurement systems, offers a number of benefits, especially insofar as the protection of HRC scenarios, as seen on the DESMA injection molding machine, are concerned.  


Unrivaled and stable measured values for enhanced productivity

The multi-pulse process in connection with special, digitalized 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 interference

The laser pulse time coding of each individual safety laser scanner is particularly crucial if - as in the case of DESMA - many devices are being operated at the same time and within close proximity of one another. In order to protect the robot on the injection molding machine, a total of four microScan3 are installed at the robot table at a height of around 200 millimeters. 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 - and their sequence is additionally modified by an integrated random generator. 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


The microScan3 safety laser scanners as an HRC monitoring solution for the DESMA injection molding machine must be able to cope with the anticipated ambient conditions. With their safeHDDM™ scanning technology, they achieve an unrivaled level of ambient light immunity of up to 40,000 lux. They are therefore very robust against dazzling – no matter 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 the reliability of the detection and protective functions whilst being very robust against dust particles in the environment or deposit formation on the optics cover. 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. This also increases the immunity to dust and deposit formation and the availability of the robot on the injection molding machine.