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In Focus - Archives Avril 2009
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When small components are assembled in medical technology, speed and reliability are required. An ideal area for microvalves.
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01.04.2009 -
Anyone who wants to handle or assemble small, light parts can really get a move on with electromagnetic microvalves. These energy-efficient valves are screwed directly onto the pneumatic actuator and thus eliminate the need for long wires. They make the tempo significantly faster and thus save compressed air, complicated wiring, and a lot of assembly time. These standardized pacesetters can even be quickly and easily integrated into existing systems.
The trend is unmistakable: Better performance, more compact, less expensive. From consumer electronics to industrial electronics, from medical technology to synthetics to watch-making: customers' requirements in this field are growing more and more, while the attainable prices are getting lower and lower. Therefore, short cycle times, low energy consumption, simple operation, and high reliability in assembly and handling are the decisive factors to be successfully competitive. The current developments at SCHUNK, the automation specialist from Lauffen, show that short paths bring immense advantages in speed and cost.
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Microvalves from SCHUNK's GAS system significantly shorten cycle times in the electronics industry.
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Cutting the cycle time in half
A system works more efficiently, the shorter the paths are and the more directly and quickly an energy impulse can have its effect. SCHUNK has taken this to heart with its automation components and has recently started offering short microvalves that the relevant actuator carries piggyback right next to itself. The youngest generation of electromagnetic microvalve from SCHUNK's GAS system speeds up the pulsing of pneumatic actuators by up to 100 percent and thus saves valuable compressed air and the troublesome assembly procedure. The electrically activated 3/2 pneumatic valves are screwed directly onto the actuator. Air flow-through and air connection threads are specified exactly for the relevant actuator, which guarantees simple assembly and installation. The miniaturized valves are completely maintenance-free, they take just seven milliseconds for a switch process, and they have an enormous life span of 900 million switching cycles.
Instead of many long, annoying pneumatic and electric lines, compact distributors are used for the pneumatic and electric supply of the valves, actuators, and sensors. One common compressed air and electric line each is all that's needed to supply almost any number of actuators quickly and energy-efficiently with the minimum of expense.
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In comparison to conventional pneumatic operation (right), microvalve technology assures low air consumption and short cycle times (left).
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The SCHUNK microvalves can be screwed directly to pneumatic grippers or rotary modules. This ensures a good tempo, eliminates cables that get in the way, and saves valuable compressed air.
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Valves put an end to performance-reducing supply cables
The hose connections between the valve and the actuator - up to now a necessary evil of pneumatic solutions - are completely unnecessary with the miniature valves. That reduces the interfering contours and the assembly expense, but it also significantly reduces the cycle times: instead of filling the supply cables first, which takes a relatively long time, the compressed air works directly on the actuator. This means even existing systems can be used much more efficiently.
"How great this effect is depends essentially on the air requirement of the actuator and on the air volume in the supply cables. The smaller the actuator, the more effective the use of microvalves is in general," explains Dipl.-Ing. (BA) Marcel Nagel, the product manager for automation components at SCHUNK. "For the pneumatic small-component parallel gripper MPG 50, which was previously supplied with compressed air by a valve terminal three meters away, the cycle time with microvalves has been reduced by about 50 percent. That means the gripper opens and closes twice as fast as before."
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Lifesaving cycle time buffer and a strong sales argument
for new systems and solutions
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For plant engineers and system integrators, the microvalves are doubly useful. Despite careful planning and construction, it frequently happens that new systems and solutions exceed the cycle times required by the customer shortly before acceptance. In these cases, the microvalves can be used as additional pacesetters. Alternatively, the higher system performance that can be obtained by means of microvalves can of coursed be included in planning in the first place and used as an effective sales argument with the customer of the plant engineer.
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The microvalves are especially effective on small actuators like the MPG small component grippers, which are also certified for class 5 clean rooms.
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Massively reduced air consumption
In view of continuously rising energy prices, SCHUNK microvalves are important for another reason: direct adaptation to the actuator massively reduces the air requirement, because in each cycle, only the piston chamber of the actuator has to be filled with compressed air, not the entire supply cable. Until now, each time the piston chamber was purged, the valuable compressed air in the cable was completely lost. In a supply hose three meters long and four millimeters in diameter, that was about ten times as much air loss per cycle as the MPG 50 connected to it, for example. Even a hose only 500 millimeters long would have created an energy consumption in this example that corresponds to that of the gripper. Using the economical and efficient microvalves in the operation of the compressors significantly reduces operating costs and investments in the performance of the entire compressed air system.
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The microvalve technology is suitable also when several actuators are used simultaneously.
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When are microvalves worthwhile?
As a rule of thumb, microvalves are generally most sensible when short cycle times are desired and the air volume in the actuator is less than the air volume in the supply hoses. To supply the two valves of an actuator, it is enough to branch the compressed air line directly ahead of the valves with a T-piece and connect the two valves. But if several actuators are to be connected, a distributor block may be preferred. Using a common compressed air line, almost any number of actuators can be supplied with the minimum of expense.
And the microvalves can offer valuable services in troubleshooting too. An LED on the microvalve shows continuously whether the valve is working properly. The adaptation of the valve on the actuator now makes this optical control possible directly on the actuator and thus significantly reduces troubleshooting time.
The possibilities that microvalves also offer in combination with other components are shown by two current examples:
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The ABV add-on valve consists of an electrical distributor box and two 3/2 microvalves, which are screwed directly to the corresponding actuator.
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Combination with an electric distributor
With SCHUNK's comfortable add-on valve ABV, both the valves and the optionally available sensors are equipped with 30 cm long prefabricated cables. These are then simply connected to a distributor box with a three-pin M8 plug.
The ABV add-on valve allows the user to remain fully flexible both in the pneumatic control of the actuator and for position monitoring. For swivel units or quick-change systems with a limited number of integrated electric and fluidic feed-throughs, the add-on valve ABV offers the opportunity to control and power several actuators separately via a central connection for compressed air and a central connection for electricity. For quick-change heads, SCHUNK now offers adapter plates with up to 14 integrated microvalves for actuating up to seven pneumatic double-acting actuators.
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Six microvalves are integrated into the SCHUNK quick-change system SWS-I-011. When there are frequent set-up processes, the system saves time and money.
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Integration in quick-change system
Another example of use is the SCHUNK quick-change system SWS-I-011, into which six of the quick-reaction microvalves are integrated and that thus replaces a complete valve terminal. This solution benefits users who, for example, frequently have to convert between grippers for products with many variants. With the innovative quick-change system, the conversion procedure now takes only a fraction of the former time, because there is no more need for the complicated re-laying of hoses for the actuators.
Instead of a bundle of cables and lines, the quick-change system now needs just one line for compressed air supply and one line for the power supply. The grippers and other tools are activated directly via the integrated valves and no longer have to be connected with hoses separately. The two supply cables can be laid inside the arm by Scara robots and led even through center bores only twelve millimeters in diameter.
Two of the six 3/2 pneumatic valves in the SWS-I-011 are required for locking and unlocking the change adapter; the other four are freely available and can be used, for example, to activate two grippers via one adapter. Electricity is supplied via a contact plate with six free contacts that have a current carrying capacity of one amp each. For example, you can supply power to up to four proximity switches and return your signals to the control unit. The practically maintenance-free system was designed for robots with a maximum payload of 16 kilograms. The life span of the poppet valves used is more than 50 million switching cycles.
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Description of function: In rest position, the lower valve seat is closed by the spring. This purges the working connection A via the outlet R. Operating the magnet closes the upper valve seat, while the lower one is opened. Working connection A is connected to supply port P in this position.
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Optional exhaust throttling protects actuators
The SCHUNK microvalves MV consist of three basic components: First, a swivel fitting with a hose connection, which is screwed into the actuator, is rotatable, and enables hose guiding without drilling. Second, the valve cartridge, where the electromagnetically operated valve sits. And third, the valve cover, via which the electric control line is connected and which enables the bleeding of the piston chamber through a bore. In addition, other accessories such as throttles or sound absorber can be placed on the valve cover with a thread. Possible exhaust throttling ensures non-impacting, gentle movements of the actuator and thus contributes considerably to a longer life span of the components.
Three sizes with standard threads allow a variety of uses
The microvalves from SCHUNK's GAS system are available in the nominal widths 1.5 mm, 2.5 mm, and 3.0 mm. At a pressure of six bar, they achieve a nominal flow rate of 45, 135, and 175 standard liters per minute respectively.
In deenergized condition, the 3/2-directional control valves are closed and can switch both overpressure and underpressure. In rest position, the lower valve seat is closed by a spring so that the working connection is purged via the bore in the valve cover. If the valve is energized, the upper valve seat closes while the lower seat opens. The working connection is the connected to the supply port and the compressed air can flow into the piston chamber.
Depending on their size, the valves are screwed in with threads of dimensions M5, 1/8" or 1/4" so that they can be integrated directly into most SCHUNK actuators as well as those of other manufacturers. The connection voltage is 24 volts, and the power consumption is 0.1 to 0.2 amps.
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11.2009
Straightaway micron-precise
In addition to a high repeat accuracy, in modern machine tools, positioning-, measuring- and handling the accuracy of the axial movement is now playing an important role. In this way, precise parts for the production or electronic industry, can be designed with a micron-precise guidance along the complete axis.
 Pour en savoir plus…
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10.2009
How Machines Can Learn To See
More and more industries tap the full potential of machine vision systems. Whether in the supermarket, on the highway, at the airport, or in the factory; pictures are being taken by a camera system and are evaluated with a computer, in order to make a fully-automatic, quick and safe decision.
Pour en savoir plus…
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09.2009
Hydraulic expansion technology for workpiece clamping
Hydraulic expansion toolholders for tool clamping (milling cutter, drills, taps and reamers) are known on the market for a long time and are appreciated for their technical advantages. They combine powerful, centric clamping with a high internal dampening. The result is an excellent surface at high machining speeds.
Pour en savoir plus…
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08.2009
Gripping - checking - measuring - preventing from damage
Intelligent sensors transform actuators to sensitive helpers in automation
Sensors used in automation are essential organs of machines and plants. While gripping modules and other actuators performed pre-defined tasks in the past, today, they are intelligent and flexible helpers in the manufacturing process due to the use of intelligent sensors. They provide the plant with important information on the process, products or components as well as plant functions. This increases flexibility, shortens manufacturing time, ensures product quality, avoids plant failures, and prevents the automation systems from damage.
Pour en savoir plus…
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07.2009
The trend towards precision toolholders
For many years, collet chucks have been popular because of their low pricing and have been the established toolholders for many machining applications. Unfortunately, the same scenario happens in many companies: Because of worry over loose tools, many machine operators are tightening the coolant tube nut of the collet mountings with oversized extensions.
Pour en savoir plus…
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06.2009
Always up-to-date with the standards - The new machinery directive in the EC
The safety of products and systems traditionally tops the priority list at SCHUNK. Since we want to partner with our customers, we are exclusively offering top-of-the-line products in quality and safety.
Pour en savoir plus…
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05.2009
Highly economical due to performance in toolholding and workholding
5-axis machines offer an enormous potential for efficiency in modern production. With sturdy machine kinematics, high axis accelerations, short chip-to-chip times, fast tool magazines and finely tuned controllers, you have all kinds of production power in a very small space.
Pour en savoir plus…
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04.2009
Microvalve Technology
- Small component handling and assembly
Anyone who wants to handle or assemble small, light parts can really get a move on with electromagnetic microvalves. These energy-efficient valves are screwed directly onto the pneumatic actuator and thus eliminate the need for long wires. They make the tempo significantly faster and thus save compressed air, complicated wiring, and a lot of assembly time.
Pour en savoir plus…
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03.2009
Reliable precision for the most well-hidden corners
Regardless of their design sophistication, it is sometimes impossible to avoid cre-ating hard-to-reach points on workpieces. All of these cases require slim toolholder systems with minimized interference contours. They have to penetrate into the most well-hidden corners, transmit sufficient torque and guarantee high precision at the same time.
Pour en savoir plus…
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02.2009
The foundry sector: a red-hot key industry
With 87,000 employees and sales of around €14 billion in 2007, the foundry sector is one of German industry's smaller branches. Its economic significance is large.
Pour en savoir plus…
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In Focus - 2013
In Focus - Archives 2012
In Focus - Archives 2011
In Focus - Archives 2010
In Focus - Archives 2009
In Focus - Archives 2008
In Focus - Archives 2007
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