Safely speeding up the cycle

siemens.com/sidoor

Machine tools made by STAMA Maschinenbau in Schlierbach are renowned for their high quality and output. Their automatic door systems have now been redesigned in the course of a modernization strategy. Result: The new, distributed com-plete drive has advantages which pneumatic and standard servo systems struggle to match. And even the safety technology is incorpo-rated in this door system.

“At first glance it is just a door, but in the final analysis it is an important protective element that has to be harmoniously and isochronously integrated into the efficiency of the overall machine automation.” For Matthias Schwarz, head of control technology at STAMA Maschinenfabrik GmbH in Schlierbach, the recent change in technology is therefore a significant innovative step.

Because, in the high quality machining centers, the Sidoor drive and control system from Siemens now handles the sequence control for the automatic door movement. Schwarz describes the reason for this as follows, “This complete solution is a phenomenal unit, that technically and economically perfects the safe, synchronized open-ing and closing of doors.”The details show what he means by this: For example, Sidoor systems are some 20 percent cheaper than previ-ous, individually adapted, servomotor door drive solutions. The advantage is even greater when it comes to the commissioning, as the control expert emphasizes, “The commissioning time for the Sidoor solution is around 75 percent shorter than that for a conventional servo drive, and requires only one tenth of the time needed for commissioning a pneumatic door controller.”

Customer STAMA Maschinenfabrik GmbH

Town, countrySchlierbach, Germany

IndustryMachine building

ProjectRedesign of the

automatic door system

© Siemens AG 2017

Easily integrated, distributed, fail-safe complete driveBackground: The door system was also reviewed to a large extent during the redesign of the multi-spindle machin-ing centers for highly efficient, precise machining of workpieces. It is crucial that the sliding doors move quickly and safely – no matter whether in a robot-equipped cell, or during manual loading and unloading.

One great advantage of the Sidoor family is that the fail-safe system works fully autonomously and can be integrated into the existing control environment by means of various communication paths, such as Profinet or Profibus.

One further advantage is that the automatic, torque-controlled door drive requires only a short learning run, during which it optimizes all essential program parameters itself. This functions as follows: Under the enclosure cover that can be detached without the need for tools, there is a blue knob that has to be pressed. Alternatively, the command can be issued by the controller.

The Sidoor controller then runs through a defined commissioning profile within a few seconds, during which it also autonomously deter-mines the dynamic mass, friction and end positions in order to calculate the optimal drive curve automatically and in compliance with standards.

Schwarz sums up as follows: “The door drive is then ready for use, safely configured and documented as a fail-safe system with Performance Level d according to the standard EN 13849-1” and comments “Commis-sioning, including complete documen-tation, cannot be completed any quicker.” The certification of electrical safety according to UL61010 1/2 201 is also new, which also simplifies the export of machines to North America markets.

Flexible, safe solution for doors weighing up to 700 kgAfter the commissioning run, the door drive has the force values required for protective devices by the standard ISO 14129 (previously EN 953). “After the learn run, we verify the fact that it passes by using a load cell,” says the control expert. This is important because the trend is toward ever larger loading apertures, and thus to heavier doors. For example, the Sidoor MDG400 NMS drive from Siemens used by STAMA can move masses of up to 400 kg. But now there is a version that can move up to 700 kg, the Sidoor MDG700 NMS, which is suitable for large, heavy doors. There is also the Sidoor MDG180, a small version ca-pable of moving masses up to 180 kg.

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STAMA Maschinenfabrik GmbH in Schlierbach is converting the doors of its machine tools one by one to the new design. The drive for the doors is the “Sidoor” from Siemens – on account of its many advantages.

Dipl.-Ing. Matthias Schwarz, head of control technology at STAMA Maschinenfabrik GmbH, “This autonomous door drive with its certified torque monitoring is a genuine marvel in many respects.”

© Siemens AG 2017

The application in the MC 338 machin-ing center is interesting and demon-strates clearly the flexible use of the NMS version. In this case, two door leaves of different sizes move together to close the machine opening. The head of control technology knows that, “A pneumatic door control could only perform such a special task with with great difficulty, if at all.” But it is no problem with the complete solution from Siemens.

The reason is that drive motors are available not only with permanently mounted force transmission, but also with a neutral mechanical interface (NMS) for variable drive transmissions. The MC 338, which has a new door design, has a stroke of 724 mm for one leaf and 300 mm for the other leaf. Sabine Fietz from Siemens, who pro-vided STAMA with detailed advice for the redesign of the door systems, explains, “The individual selection of the belt wheels that are fixed on the motor shaft of NMS motors by feather keys enables even such asymmetrical door solutions to be easily adapted to meet requirements.” In this respect, users have a completely free choice of power transmission system, such as toothed belt, chain, toothed rack, etc.

Outstandingly harmonious door kinematicsMachine tool doors take about 4.5 seconds to open. Matthias Schwarz described the outstanding feature in comparison to pneumatic solutions as follows, “There are no jerky move-ments with Sidoor controllers, and

users even tell us how exceptionally harmoniously the door kinematics function in our machines.” Beauty is one thing, cycle time another, and that is what counts. Here again, the distrib-uted complete drive is proving to be the optimal solution, because the system parameterizes itself during the learn run.

It is also advantageous that the control can distinguish between manual loading and enclosed robot equip-ment, which works significantly more quickly. Sabine Fietz emphasizes that

“the drive always makes ramp move-ments that is gentle on the material, so here again there is a noticeable difference to pneumatic drives.” Mat-thias Schwarz adds, “Furthermore, after the learn run, the Sidoor drive is perfectly adjusted to the weight and torque distribution of the door systems and the driving profiles remain pre-cisely reproducible for the user, where-as pneumatically based solutions always run the risk of the door kine-matics changing if the pressure level changes during everyday operation.”

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The independent “Sidoor” controller can meet all necessary standards relevant to door and gate drives safely and without additional effort.

The new NMS (neutral, mechanical interface) drive motors give users the freedom to use their own solutions for transmitting force, such as belts, chains, toothed rack etc.

Sabine Fietz, Machine Tools Systems Sales at Siemens, “Even asymmetric door solutions can be easily realized by the individual selection of drive wheels, which, in NMS motors, are fastened to the motor shaft by feather keys.”

© Siemens AG 2017

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Quickly integrated into the control and safety technologySchwarz regards the extremely short development time as another im-mense advantage of the new solution. Sabine Fietz provided him and his colleagues with a test kit, with which all capabilities of the door drive could be experienced to some extent “off-line” in the office. Result: The new control solution was fully adapted to the STAMA machine tools within two or three days and could then be copied into the machine control system.

The safety technology was completely verified in just one day. Matthias Schwarz described the greatest advan-tage as follows: “The distributed door drive is regarded as a self-sufficient safety system that monitors itself up to Performance Level d and is corre-spondingly certified. Therefore no changes need to be made to the fail-safe machine program.”

Simplified engineering through certified torque monitoringCommunication with the machine controller takes place via Profinet, Profibus or USS, which allows great flexibility in the selection of controller. For commissioning, only the appropri-ate data block is imported into the controller, the door drive then takes

over the entire control itself. If an unsafe state occurs with the door drive – through deficiencies in the internal plausibility and function tests or on account of outside influences – the door controller switches to a safe state and reports this to the safety section of the machine control system. In this way, the required safety is achieved in every situation.

If the Sidoor controller detects an obstacle, it reverses totally or partially, depending on the setting of the door, and notes the position of the obstacle. On renewed closing or opening, the door moves carefully just before it passes the position of resistance encountered during the previous movement. If the obstacle is still there, it is only touched at a lower speed. If the way is clear, the door is acceler-ated again to keep the lost time as short as possible. The machining process does not start until the door is completely closed.

In conclusion, Schwarz says, “Addi-tional, fail-safe door sensor technology is not required on account of the certified torque monitoring, which saves us from further engineering effort.” Only a two-channel, moni-tored, mechanical locking switch reports proper closing of the doors to the higher-level machine control system. This additional safety derives

from the European Machinery Direc-tive, according to Schwarz.

The distributed complete solution is the optimal alternative to previous door systems.Machining centers from STAMA Maschinenbau are also subject to the basic requirements of short cycle times, high availability and reliable production output. The doors to the machining compartment are also subjected to extensive tests to see whether they still meet the require-ments of modern machining manufac-turing. During the redesign of a door system, those responsible decided against individual pneumatic and servo motor solutions.

The reason is that there are modern, efficient alternatives, such as the complete Sidoor distributed solution from Siemens. This door and gate drive contains everything that a powerful, safe closing system requires. It works autonomously, is fail-safe up to Performance Level d according to EN 13849 1, and moves torque-con-trolled doors up to a dynamic mass of 700 kg. For Matthias Schwarz there is no doubt: “This enables us to make the cycles of our automatic door systems faster, safer and more harmonious than any other previous solution.”

The editorial version was published at MM Maschinenmarkt, edition KW36 2017.

© Siemens AG 2017

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