Hydraulics Online Application Articles

SmartBird is an ultralight but powerful flight model with excellent aerodynamic qualities and extreme agility. With SmartBird, Festo has succeeded in deciphering the flight of birds one of the oldest dreams of humankind.

This bionic technology-bearer, which is inspired by the herring gull, can start, fly and land autonomously with no additional drive mechanism. Its wings not only beat up and down, but also twist at specific angles. This is made possible by an active articulated torsional drive unit, which in combination with a complex control system attains an unprecedented level of efficiency in flight operation. Festo has thus succeeded for the first time in creating an energy-efficient technical adaptation of this model from nature.

New approaches in automation
The functional integration of coupled drive units yields significant ideas and insights that Festo can transfer to the development and optimisation of hybrid drive technology.

The minimal use of materials and the extremely lightweight construction pave the way for efficiency in resource and energy consumption.

Festo already today puts its expertise in the field of fluid dynamics to use in the development of the latest generations of cylinders and valves. By analysing SmartBird’s flow characteristics during the course of its development, Festo has acquired additional knowledge for the optimisation of its product solutions and has learned to design even more efficiently.

http://www.pneumaticsonline.ca/flash/Festo/7/

Wafers, cells, strings, glass, foils and modules Schmalz offers groundbreaking vacuum handling solutions for the entire photovoltaic production supply chain.

The task: optimum handling for complex processes
Manufacturing solar cells and photovoltaic modules involves a series of complex individual processes. The individual process steps are characterized by various environmental conditions such as heat, chemically aggressive substances, mechanical pressure, heat stress and plasma processes. Common to all manufacturing steps are the highly demands that are inherence to the processes that are placed on throughput speed, which in turn determine the production cycle and ultimately the output quantity.
But even more important than quantity is ensuring a reproducible quality and the highest possible light yield for minimum cost. For this reason, the handling of cells and modules is crucial for the economical production of PV modules.

It is not only the workpieces that are extremely sensitive in terms of damage during handling: The crystalline silicon wafers are only 120 to 180 micrometers thick, while foils are as thin as 20 to 100 micrometers and are partially coated.Despite high process dynamics and fast transport, it must be guaranteed that indentations, transportation marks and breakage are avoided while maintaining maximum process safety. Optimum handling plays an especially important role in the current climate, as state funding of solar/photovoltaic systems is to be cut drastically: Thanks to optimized production processes, greater efficiency and higher output with fewer breakages, the manufacturer can significantly reduce production, assembly and finishing costs, making investment in PV systems lucrative for the end consumer.

The solution: innovative vacuum technology
Unstacking, positioning, buffering, stacking, fixing, aligning vacuum technology specialist J. Schmalz GmbH recognized the value of parts handling in photovoltaic production at an early stage and we offer sophisticated solutions for PV production system expansions and upgrades.
Our product portfolio boasts not only a specific range of components for gentle handling that leaves no marks, but also complete gripping systems and solutions for manual handling. Schmalz offers the ideal handling solution for every process step: perfectly tailored to the workpiece and to the specific process and environmental conditions.

Vacuum grippers for gentle wafer and cell handling that leaves no marks
The handling technology found in the SWG (Schmalz Wafer Gripper) special gripper is found nowhere else in the world: As the first supplier, Schmalz provides a solution makes process-safe, slip-free and damage-free handling with cycle times of less than 1 second possible. The modular design allows for simple adaptation to a wide range of wafer formats and process requirements. Using additional modules, double-layer control, on the flyy breakage detection and position determination are possible, all of which enhances process safety.

Suction grippers from the SGPN range are distinguished by an elongated sealing lip and an inner support. The geometry prevents the workpiece from being pulledd into the suction gripper, while the especially soft, natural rubber material minimizes microstructural damage to the sensitive wafers and solar cells. Depending on the process step, Schmalz also offers various suction grippers made of HT1: They can withstand temperatures from -30 C to +170 C, are abrasion-proof and they ensure that no marks are left even on raw wafers made of pure silicon.

Vacuum gripper systems for automated glass and module handling
The vacuum specialist configures gripper systems from the range of standardized components based on process requirements: Suction grippers, mounting elements and vacuum generators result in a system that, when connected to a robot, makes efficient handling of glass sheets, foils or complete modules possible.

Fully thought through
Schmalz complements the automated vacuum handling product range with handling solutions for ergonomic manual module handling:

The JumboErgo vacuum tube lifter with a built-in PSE swiveling unit allows modules with coated and structured glass to be lifted and transported ergonomically, process-safe and without leaving marks. Vacuum components, vacuum gripping systems, vacuum lifting units − Offering sophisticated solutions for all process steps in the handling of PV components is not the only way that Schmalz provides proof of its expertise.

Compressed air is one of the least efficient forms of energy that is used in modern manufacturing plants. It takes seven to eight times more electricity to produce one horsepower with compressed air than with an electric motor. Compressed air is often the largest end-use of electricity in a plant.

There are many actions a plant manager can take that will quickly and easily increase efficiency of their compressed air system and decrease compressed air energy usage by 20% or more. Here, I will discuss only one of these actions, that is, installation of a Dewpoint Demand Switching system for the heatless desiccant dryer (HDD). The HDD is typically a major use point of compressed air and some of these dryers will use up to 18% of the compressor capacity just to operate the dryer.

How does a desiccant dryer operate?

In order to understand how we can improve efficiency, we must first understand the basic operation of this type of dryer. The HDD operates to maintain the compressed air at a specified pressure dewpoint; usually 40˚ or 70˚C.

The dryer utilizes two vertical pressure vessels (sometimes called dual towerss) filled with a desiccant such as activated alumina, silica gel, or molecular sieve. The compressed air passes through the desiccant bed before being distributed to the plant.

As the air passes through the desiccant, water vapor is removed from the air through a process called adsorption. Adsorption is defined as the binding of molecules or particles to a surface. The binding to the surface is usually weak and reversible.

Regeneration consumes energy

As the compressed air is passing through one vessel where water vapor is being adsorbed, the desiccant in the other vessel is undergoing regeneration where the water vapor that was previously adsorbed is removed.

Regeneration is accomplished by extracting a portion of the dry air as it exits the active vessel, expanding this air to atmospheric pressure and passing it over the desiccant that is to be regenerated.

The air that is extracted as it exits the active vessel is called purge air. As the purge air is expanded to atmospheric pressure it becomes very dry and will easily separate the water vapor molecules from the desiccant beads causing the regeneration of the desiccant bed.

Purge air and the energy required to produce the extra compressed air to fulfill the regeneration requirement is the direct energy cost that is required to operate the heatless desiccant dryer.

A savvy plant manager can capitalize on energy savings by installing a Dewpoint Demand Switching system.

Switching based on worst case conditions

The cycle of the dryer refers to the time between switching from one tower to the other. A typical cycle time is some ten minutes. During this ten-minute cycle, the dryer will switch one time so that each tower is online for five minutes and regenerates for five minutes. The cycle time is determined by the manufacturer and will depend on the dewpoint that is specified and the amount of desiccant in the vessels. The cycle time and amount of desiccant is determined based on worst case conditions;
full rated air flow of the dryer, 35 C air temperature, 100% relative humidity, and 100 psig (7.9 bar) pressure. The dryer is constantly demanding purge air based on this design. For example, if a dryer is rated to provide a 40 C dewpoint at a maximum flow of 1000 cfm (28 m3/min) and requires 15% purge air, it means that the dryer will continuously consume 150 cfm (4 m3/min) of the output from the compressor, regardless of the actual conditions and actual compressed air flow. In this specific example, the purge air requirement is equivalent to running a 35 horsepower compressor just to
provide purge air to the dryer. With such a fixed cycle, the dryer will demand 150cfm (4 m3/min) purge air every minute of the day, regardless of the actual conditions and demand of the plant and regardless cassapaf the real capacity of the desiccant bed.

Dewpoint demand switching optimizes the cycle

As we know, it is rare that a plant operates in such a way that it requires 100% of the compressor/dryer capacity 24 hours a day, seven days a week. The demand for air will vary throughout the shift and from day-to-day, depending on shift and plant operation, etc. The inlet air conditions will also vary depending on the ambient temperature and relative humidity.

This is where a savvy plant manager can capitalize on energy savings by installing a Dewpoint Demand Switching (DDS) system. With a DDS system installed, rather than the towers switching every five minutes and demanding constant purge air, the towers switch based on the dewpoint temperature as measured at the outlet from the dryer. Savings can be made because the towers will not switch back and begin using purge air until the hygrometer senses a degrading dewpoint temperature.

The DDS system ensures the full use of the desiccant bed, increasing efficiency and thus reducing the use of purge air, which in turn reduces the use of electricity.

A DDS system consists of a hygrometer that can reliably measure the dewpoint of the compressed air as it exits the active tower, and which is also able to generate an output signal that can be detected by the dryer operating system.

Retrofit your dryer for DDS

Is it possible for an existing dryer to be retrofitted with a Dewpoint Demand Switching system? The answer is yes, as long as the dryer operating system allows for controlled tower switching. If you are not sure, consult the dryer manufacturer or read the operating manual.

Retrofitting a dryer with this type of system is relatively easy. The first step is to confirm that the dryer will accept a signal and operate the switching process based on that signal. The second step is to find the correct type of hygrometer that will operate accurately, provide a suitable output signal, is easy to install, offers low maintenance and is resistant to contamination. There are several different types on the market, each with different pros and cons, and it is important to know what questions to ask the manufacturer to ensure that you reap rewards and not headaches from installing a Dewpoint Demand Switching system.

Vaisala DRYCAP Dewpoint Transmitter technology is the reliable choice. The DMT142 and DMT242 transmitters are compact and rugged. The DMT340 series transmitters, with a variety of options, provide the user with a complete solution, and the hand-held DM70 is a practical tool for spot measurements.

###

This Article is Courtesy of Vaisala

Vaisala Inc.
10-D Gill Street
Woburn, MA 01801, USA
Phone:1-888-VAISALA (824-7252)
+1 781 933 4500 International Calls
Fax:+1 781 933 8029

Very thin objects such as solar cells or wafers pose the most stringent requirements when it comes to handling technology. Such substrates are very fragile and, with diameters of up to 300 mm, they have a thickness of merely 0.6 to 0.8 mm. The thickness of thin wafers can even be less than 100 m. Extremely sensitive objects can nevertheless be securely handled, as SCHUNK demonstrated at Automatica 2008 with a machine from its partner Zimmermann&Schilp Handhabungstechnik GmbH that was especially designed for trade show exhibitions. This involves a robot handling solar cells using a non-contact gripper. It picks up the eight-inch large, 160 m thick cells from a depositing unit and places them on the linear transfer unit where they can be further transported without any mechanical contact.

The working principle of the ultrasonic gripper used here is based on so-called “near-field levitation”. This involves an ultrasonic generator being moved close to the workpiece and creating a pressure as a result of the cyclic compression and decompression of a thin film of air between the ultrasonic generator and the workpiece. The pressure protects the workpiece from direct mechanical contact.

To apply this reaction to the construction of grippers, air is simultaneously extracted through holes on the gripper face to create a vacuum. While the vacuum is holding the workpiece, the pressure created by ultrasonic waves in the layer of air prevents the workpiece from coming into contact with the gripper face. Equilibrium is created between the weight of the workpiece, the suction force of the vacuum, and the back pressure of the film of air, in which even the thinnest substrate can be safely held. The workpiece is gripped without friction, and yet securely, without the need for compressed air. The distance between the ultrasonic gripper and workpiece can be between 0.05 and 0.5 mm, and since there is neither friction nor particle contamination, the process is also suitable for use under clean-room conditions.

When the shape of the gripper corresponds to the shape of the component, a fluid-mechanical effect generates a centering force in the case of small components. This force makes it possible to have fast accelerations or to turn the gripper together with the component. When larger parts are to be handled, there are lateral stops that prevent the workpiece from slipping when the gripper moves. Since these stops are only in position to absorb lateral acceleration, there is only minimal mechanical clamping required for the component.

This process, which is generally suitable for all reverberant workpieces made from metal, plastics, or ceramics, can be used for constructing universal grippers and transfer tracks as well as for the non-contact stabilizing of workpieces with unstable forms. Such ultrasonic components are easily integrated into existing machines and can have different sensors added to them. By avoiding mechanical contact between component and workpiece, non-contact gripping reduces losses due to handling damage and leads to an increase in profits.

SCHUNK Inc.
211 Kitty Hawk Drive
Morrisville, NC 27560

Phone: 919.572.2705 or
800.772.4865
Fax: 919.572.2818
www.schunk.com
[email protected]

Short cycle times and reliable, high repeatability are top requirements of manufacturers of plastics processing machines. Bosch Rexroth meets this requirement with the SY.DFE, an electro-hydraulic closed-loop control system with 100,000 units installed worldwide. The SY.DFE uses a variable displacement axial piston pump for controlling pressure, displacement and power without throttling losses in the power branch.

The SY.DFE provides the ultimate in hydraulic energy efficiency, electronically controlling both flow and pressure with exceptional speed and precision. A proven combination of a variable displacement axial piston pump of swashplate design and innovative proportional control electronics, the SY.DFE provides efficient, reliable controlling of the pump.

The SY.DFE was launched at the plastics processing trade fair in DDsseldorf in 1989, and with 100,000 units installed, it demonstrates the exceptional value it has provided in multiple plastics processing applications since its debut. Primarily used in injection molding machines, the system is based on a Rexroth A10VSO or A4VSO axial piston pump. By adjusting the pumpps swashplate, flow and pressure can be infinitely varied, and the required flow and pressure can be generated fast and accurately for specific machine functions.

In addition, functional sequences in an injection-molding machine can be precisely controlled with the help of the SY.DFE. The flow control works without pressure losses in the power branch, which significantly increases the hydraulic efficiency within the machine. Moreover, the total efficiency of the machine is increased due to the high repeatability of the control.

Rexroth offers this system in three versions: SYDFE1 with external closed-loop control electronics, the SYDFEE, with analog, integrated functions, and the SYDFEC, which offers integrated, digital closed-loop control electronics and the optional field bus controlling via CAN, so that users in the plastics processing industry can benefit from a proven plug-and-play system.

Bosch Rexroth Canada is the Canadian partner company of Bosch Rexroth AG, the worldwide leader in Drive & Controll. Under the brand name of Rexroth the company supplies more than 500,000 customers with tailored solutions for driving, controlling and moving machinery used in industrial and factory automation as well as in mobile applications. As The Drive & Control Company, Bosch Rexroth develops, produces and sells components and systems in more than 80 countries. In 2006 the company of the Bosch Group achieved sales of approximately 4.9 billion Euro with more than 29,800 employees.

Company Information:
Bosch Rexroth Canada
Ontario, CANADA
www.boschrexroth.ca
[email protected]

Ken Davis, Business Development Manager, Advanced Machine & Engineering Co.

The Europeans have the answer to safeguarding hydraulic and pneumatic presses from catastrophic failure. The good news: now itts available here in the U.S.

An ounce of prevention is worth a pound of cureethe old adage rings especially true for the thousands of press operators today trying to reduce their production costs and stay competitive with higher speeds, smaller batches and keep your fingers crossed greater machine uptime. The cost today for a catastrophic press failure? On the low end, certainly thousands of dollars in lost production time and die replacement costs. On the high end, the loss of a key operator due to injury or a customer that takes his business elsewhere rather than run the risk of falling behind schedule again.

Sure, todays most modern hydraulic and pneumatic presses have a variety of OSHA mandated protection systems in place to ensure operator safety. Guards, interlocks, electro-sensitive and opto-electronic devices, emergency stop devices and other redundant systems have helped make presses safer in recent years. But when it comes to safeguarding the presses themselves from expensive damage to the press or dies, standards in the U.S. fall well short of their European CEN counterpart, which states in prEN 693 Machine tools Safety Hydraulic Presses: Where there is a riskkfrom a gravity fall of the slide /ram a mechanical restraint device, e.g. a scotch, shall be provided to be inserted in the presssOn presses with an opening stroke length of more than 500 mm and a depth of table of more than 800 mm, the device shall be permanently fixed and integrated with the press. A similar CSA Standard (Z142-02) exists in Canada

Faulty vs. failsafee. For most American press operators, however, a ratchet bar, locking bolt or latch is all thatts standing between them and a catastrophic crash should hydraulic or pneumatic pressure be lost suddenly or the lifting mechanism experience a mechanical breakage. When functioning properly, the ratchet system — usually running the length of the press stroke– does an adequate job of arresting the fall of the ram and preventing a catastrophic crash. A spring latch will automatically extend to engage the teeth of the ratchet at some point before a crash can occur. Unfortunately, the ratchet is a wear part that after hundreds, even thousands of press cycles can begin to exhibit signs of wear that are difficult to detect visually, and probably cannt be heard, by even the most experienced operator. Over time, the ratchet teeth, spring and latch typically begin to wear, since the spring latch makes contact with the teeth (but doesnnt engage) on the upstroke of the ram every time the ram is raised for the next part. The ratchet, and even the end of the spring latch, can wear to the point where a fall cannt be prevented.

In addition, locking bolts and latches often operate only at the top of the stroke, and ratchet bars at fixed interval positions. Consequently, the ram must often be retracted to its full stroke position each and every part, despite the fact that the part requires only a short opening stroke. This can add considerable, and very expensive, non-productive time to the cycle.

But in Europe, Canada and elsewhere in the world, most presses are equipped with a SITEMA Safety Catcher, which satisfies the requirements of CEN and CSA safety standards, foolproofs presses from a catastrophic crash, and allows the operator to optimize the stroke for any size part. The SITEMA Safety Catcher works a little like the Chinese Finger Trapp you probably played with as a child. You could easily put your finger in one end of the paper cylinder, but it was very difficult to retract it. In fact, the harder you pulled the more clamping power the simple paper cylinder seemed to exert on your finger. The SITEMA Safety Catcher works in similar fashion. If hydraulic or pneumatic system pressure fails, or if a rope, chain, belt or toothed drive breaks, the SITEMA Safety Catcher prevents the load from crashing down at any position of the descent. Better yet, the system is self-intensifyingg, so that as downward force increases, so too does the Safety Catcherrs clamping force.

Herees how it works (see Fig. 2 and 3):

1) A cylinder rod is mounted to the top of the platen extending through the press crown and the Sitema safety catcher housing (Figure 2). The safety catcher housing is securely fixed to the machine crown / frame and surrounds the rod which is free to move during normal operation. Wedge shaped clamping jaws inside the housing are held with hydraulic or pneumatic pressure to keep the wedges in position so that the rod can move freely.

2) This Safety Catcher instantly becomes effective when hydraulic or pneumatic pressure is lost or released. A spring causes the clamping jaws to firmly contact the rod. As a result, any downward movement of the rod initiates the self-intensificationn feature securing the load.

3) Significantly, the energy of the falling or sinking load is used to apply additional clamping force if needed. In other words, self-intensifyingg friction created between the clamping jaws and the cylinder rod draws the jaws into their maximum clamping position after only a few millimeters of movement.

4) If the load continues to increase, the Safety Catcher will continue to hold the rod in a fixed position until a pre-determined static holding force limit is exceeded (approximately 3-4 times the retain force). Beyond that point, the Safety Catcher continues to safely hold the rod, with a braking action dissipating the kinetic energy of the falling mass while it continues to resist the downward movement of the platen.

5) Only when hydraulic or pneumatic pressure is restored in conjuction with the equivalent reverse movement of the rod are the clamping wedges released, making the SITEMA Safety Catcher inherently failsafe.

SITEMA is catching onn everywhere. From presses to large hydraulic elevators to stack loaders to machine tools in almost any application where a large load is traveling and the potential for a catastrophic mechanical failure exists SITEMA Safety Catchers have been applied successfully and in increasing numbers, as safety standards toughen around the world. They are available in a variety of sizes to meet most common press sizes, including the very largest. Most importantly, they are readily available today in the United States through Advanced Machine and Engineering Co.

About AME

AME is a global manufacturer and distributor of precision machine components, fluid power components, fixturing/workholding, power drawbar and spindle interface components, and saw machines and blades. The company also designs and builds special machines for a variety of industries, and provides machine rebuilding, retrofitting and contract manufacturing services. AME has partners and customers around the world and across the U.S. To learn more, visit www.ame.com.