Experience, tradition and passion

Experience, tradition and passion – these values ensure the five-star quality at the five-brother company Bühler Bedachungen und Bauspenglerei from Romanshorn in Switzerland, a business specializing in roofing and architectural sheet metal. Quality is the top priority for the family business – particularly when it comes to selecting its partners and suppliers. Among these is the Swiss company Jorns AG, which supplied the new double bending machine, model TP-150G-RH-UV-SL-1250-CP200-6.4-mp, including safety concept for the architectural sheet metal area as well as the manufacturer for optical sensors, which ensures the corresponding safety at work for man and machine, Leuze electronic.

Safety for man and machine
In addition to the Lausanne theater, the gondola station in Wildhaus, the elephant enclosure at the Rapperswil zoo and the tribune roof in St. Moritz for the Olympics, Chäserrugg is one of many renowned projects completed by Bühler Bedachungen und Bauspenglerei

Safety for man and machine is required not only by safety-relevant, international standards. Protecting man and machine from dangerous processes is a matter of course for the 35-person company. "If a new machine is used, such as the new TwinMatic-Pro 150 bending machine from Jorns here in our architectural sheet metal operations, it must satisfy the latest requirements on safety technology," says trained sheet metal worker Bruno Bühler. When selecting the safety concept, he relied on the consulting expertise of the manufacturer of this machine, Jorns AG from Lotzwil. Thanks to positive experiences with other projects, Jorns used the RSL 430 safety laser scanner from Leuze electronic, which optoelectronically safeguards access to the long, front side of the machine. The RSL 430 is centrally positioned under the bending basin, ensuring that the maximum radial range of the sensor can be used. The area in front of the machine can thereby be safeguarded with just one sensor.

Fully automated work process 

TwinMatic-Pro 150 is the name of the new bending machine from Jorns AG used in the architectural sheet metal area of the company, which replaced a nearly 20-year-old machine with similar functionalities here. The new machine enables the bending of a very wide range of types and thicknesses of sheet metals in a fully automated process: aluminum, zinc, copper, steel. Only when loading and removing the metal sheets does the machine need to be handled manually. As soon as the machine operator crosses the red line on the floor located approximately 80 cm from the bending machine, thereby entering the danger zone of the machine, his movement is detected by the RSL 430 safety laser scanner and the machine comes to an immediate standstill. Should this safety monitor fail, there is a "safety net" in the form of a step bar. If this bar is actuated by the operator’s foot, it presses against an EMERGENCY-OFF command switch that brings the machine to a standstill in a fraction of a second. "It’s good to have a double safety net – fortunately, we’ve never had to make use of it. The RSL 430 safety laser scanner works reliably and fault-free, making it the optimum solution for us," says sheet metal worker Bruno Bühler, who usually operates the bending machine himself.

The functionalities of the new safety laser scanner convince
Sheet metal worker and machine operator Bruno Bühler at the control panel

Due to its innovative capacity, the RSL 400 safety laser scanner – which is available in various models – convinced not only end users such as Bühler since being launched on the market at the end of 2015. It also convinced juries of experts, claiming multiple awards in 2016 – including the GIT Safety Award, the Industriepreis as well as the Handling Award. [Textflussumbruch]The safety laser scanner functions as follows: it transmits periodic light pulses via a rotating deflection unit. These are scattered in all directions by obstacles, such as persons entering the danger zone. A part of the light pulses is received again by the safety laser scanner and evaluated. The scanner calculates the precise position of the machine operator from the propagation time of the radiated light and the current angle of the deflection unit at that time. If this is located within the previously defined protective field, the safety laser scanner executes a safe switching function. "In our case, this happens as soon as the machine operator crosses the safety line marked on the floor with red signal color at the long, front side of the machine," says Pascal Guyot, director of control engineering at Jorns AG. Should this occur, the safety-related switching outputs are switched off. The required safety distance is calculated on the basis of safety-related standard DIN EN 999. Playing a role here are factors such as the approach speed relevant to safety and height of the protective field above the ground. Furthermore, the stopping time of the machine as well as additional distances, e.g., for system-related measurement errors, must also be taken into account.  

Monitoring from a bird’s eye view 

All-round protection from all machine sides is, however, not provided by a single safety laser scanner positioned centrally under the bending basin of the bending machine. Depending on how they are attached, at least two safety sensors would be needed to achieve this. With just one safety laser scanner, cutting in automatic mode would only be possible in inching mode. Obstructions could also occur if the sheet was to protrude far outside of the machine when bending sheet metal top-down. Bühler therefore decided to mount a second RSL 430 safety laser scanner to monitor the machine room from above, thereby reducing the depth of the danger field to 80 cm. The second scanner is attached to the ceiling with an iron chain and has an operating range of 8.25 meters with a resolution of 70 mm and a detection range of 270°. The position of the safety laser scanner is always based on the sensor that monitors the bending line. Note that the control panel is also detected as an object and must therefore be located outside of the danger zone while in automatic operation. "If the area of the control panel were to be removed from monitoring, blind zones would arise within the danger zone due to shadowing. In addition, blind spots would occur between the stands and behind the machine, which must absolutely be safeguarded," says Bojan Zmijanjac, Area Sales Manager at Leuze electronic Switzerland

A comprehensive safety concept that convinces
Bruno Bühler (Bühler - Bedachungen und Bauspenglerei) and Tobias Wüst (Leuze electronic) are convinced of the safety concept implemented at Bühler

With the positioning of two RSL 430 safety laser scanners, Jorns Bühler recommended an integrated, comprehensive safety concept for all-round machine protection that has been proven in practical use and that convinces. Tobias Wüst, managing director of the Swiss subsidiary of Leuze electronic in Fluringen, emphasizes the competence of the manufacturer and innovation leader in the area of optical sensors: "Safety sensors have a great deal to offer. Reliable safety laser scanners require many years of experience. With the RSL 400 safety laser scanner series, Leuze electronic has succeeded with a development that combines maximum reliability and performance with simple operation."

About the companies 

Jorns AG, Switzerland

The Swiss manufacturer of bending machines, double bending machines, compact strip cutting lines, gutter machines as well as accessory machines for processing thin sheet metal, Jorns AG, is a globally active family business specializing in the areas of architectural sheet metal processing, roofing and hall construction. Jorns AG has more than 40 years of experience and supports the success of its customers with application-oriented systems and services for processing thin sheet metal. Focus of the range of products is the process chain for the cutting and bending of long profiles

Bühler – Bedachungen und Bauspenglerei AG, Switzerland 

Since 1964, Bühler – Bedachungen und Bauspenglerei in Romanshorn, Switzerland, has stood for outstanding products and services in the areas of roofing, architectural sheet metal work, facade construction, photovoltaics, scaffold construction and mobile crane use. Long-standing customers value the technical competence, experience and tradition of the "five-brother-company" taken over from their father as well as the personal consulting, support and passion of the complete solution provider. 



Leuze electronic is one of the world's innovation leaders in optical sensors and is internationally known as a leading manufacturer and solution provider in electrical automation. Its main focus is on the areas of intralogistics, packaging industry, tool manufacturing and automotive industry as well as medical technology. The product range includes switching and measuring sensors, identification systems, solutions for image processing and data transmission and also occupational safety components and systems. Founded in 1963, the company, based in Owen (Germany), possesses specific application know-how as well as comprehensive industry knowledge. More than 1000 employees at 22 locations are involved in development, production, sales and service – supported by more than 40 sales partners around the world. Innovative product developments, tailor-made complete solutions and an extensive range of services stand for the "Smart Sensor Business 4.0" at Leuze electronic.