Sealed Two-Finger Parallel Gripper
March 25, 2010 by Larry Boulden
Filed under Actuators, Grippers
The successful DPGplus series of sealed 2-finger parallel grippers has been extended with sizes 240 and 300. The pneumatic drive with oval pistons and the multi-tooth guides ensure precise and reliable gripping. This ensures a high level of machine up time and high returns from production and assembly applications.
The DPGplus sealed 2-finger parallel gripper is an expert at handling rough or dirty workpieces. It is suited for loading and unloading in harsh environments, like grinding machines, lathes, and milling machines. It is also suitable for use in painting systems, powder coating systems, or underwater.
The sealed grippers of the DPG-plus series feature sealing class IP 67 for the highest sealing in its class, with moments between 30 Nm and 160 Nm, (22 Ft-lb-118 Ft-lb) depending on the direction of load and size of the unit and grip forces up to 11,700 N (2,630 lbf). The high sealing class and performance are made possible by combining a multi-tooth guide with a round sealing surface of the base jaws toward the outside.
SCHUNK Inc.
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DUAL SENSOR FOR C-GROOVE CYLINDERS
March 25, 2010 by Larry Boulden
Filed under Actuators, Cylinders, Positioning sensors, Uncategorized
TURCK’s BIM-UNR line of compact magnetic cylinder position sensors now includes a dual sensor designed for detecting short and long stroke C-groove cylinders. BIM-UNR dual sensors provide a distinct advantage by combining two sensors through one cable connection to speed installation, as well as lessen wire costs and connection points. This design makes the sensor particularly beneficial in areas where multiple cylinders are used, as it only requires a single cable. With dimensions of 2.9 x 4.6 x 18 mm, Delivering reliable performance and high EMC immunity, thisl sensor provides an exceptional alternative to ordinary cylinder position sensors. The sensor mounts within C-groove cylinders with no accessories required. Plus, it can be inserted into a C-groove from the top rather than from the side, further simplifying installation. On the sensor’s side is a built-in tab that keeps the sensor in place to facilitate one-handed mounting. As the mounting screw is located near the cable exit, the sensor remains fastened even if the cable is pulled. TURCK |
Solenoid Valves Are No Match For Jet Valves
Festo is launching a new series of jet valves that are said to provide exceptionally rapid switching times of less than 1ms – an order of magnitude faster than standard pneumatic solenoid valves. Based on a new design featuring just one moving part, the new MHJ series jet valves also provide very high switching time repetition accuracies, and are claimed to have an industry-leading service life of 10billion switching cycles. The jet valves are suitable for diverse high-volume sorting applications, especially in the food processing and waste recycling industries.
Festo’s MHJ series jet valves are designed for use with standard 40um filtered compressed air supplies and accommodate a wide range of operating pressures from 0.5 to 6bar. They offer a choice of three 2/2-way fast-switching models, with nominal flow rates of 50, 100 and 150 litres per minute. The valves employ a special short-stroke solenoid and patented damping plate developed using extensive CAE modelling of the magnetic, temperature and flow characteristics to optimise the switching characteristics. To switch at this speed and provide such a long life, the novel design dispenses with dynamic seals and lubrication. The design of the solenoid and damped flat plate also enables the valve to deliver the consistent switching repetition of less than 0.1ms required throughout the operating life of specialist sorting machines.
MHJ series jet valves have a trigger signal voltage range of 3 to 30V DC, enabling them to accommodate standard 5V PLC-level signals without any need for voltage conversion. The valves have a power consumption of 7W, which can be reduced to 2W after the initial turn-on period by use of a holding current control feature, which can be supplied by Festo either integrated into the coil assemblies or incorporated into the application control board.
Festo’s MHJ series jet valves are available as individual units with integrated push-in fittings and can also be supplied with sub-bases for manifold mounting. Festo also produces customised manifolds that enable groups of valves to share the same air supply; these can be fitted with integral jet nozzles, if required.
Hydrogen Hybrid Bus Running On Canadian Streets
March 18, 2010 by Larry Boulden
Filed under Air Preparation, Pressure Sensing, Tubing, Vacuums, Valves
An innovative application for pneumatics helps power a unique vehicle. The Hydrogen Hybrid Bus (HHB), was built by Golden, CO-based Proterra with funding from the U.S. Federal Transit Administration (FTA) as part of the National Fuel Cell Bus Program, and is managed by the Center for Transportation and the Environment (CTE).
The HHB is operating on existing bus routes through the Victoria, BC adding hilly, cold weather operations to the ongoing evaluation of the bus. The bus received significant positive exposure by operating throughout the Winter Olympic Games and was featured as part of a formal demonstration and media event on March 11, sponsored by the Southern Hydrogen & Fuel Cell Coalition (SHFCC).
The bus is powered by lithium titanate batteries and two 16 kw hydrogen fuel cells, producing clean electric power in a lighter, quieter, and more aerodynamic design that is better suited for today’s transportation demands. The only emission is water vapor. Although the bus was certified for use in the U.S., it successfully underwent additional testing and safety inspections in order to be driven in Canada. With more than twice the energy efficiency of other hybrid buses and four times that of conventional diesel buses, Proterra buses combine tremendous environmental benefits with substantial cost savings to the operator.
Hydrogen Hybrid Bus Details:
- The HHB is an electric hybrid bus that was purpose built for an electric drive train and can be configured with a wide variety of ‘engines’ or as battery electric only. This version uses clean fuel cells as the ‘engine’.
- The HHB carries 29 kilograms of hydrogen on board and can achieve up to a 480 km range.
- The use of composite materials for the body makes it much lighter – and stronger – than conventional buses.
- Initial BC Transit evaluation has determined that the fuel economy for this bus in shadow service is approximately 70% better than typical diesel buses.
- South Carolina and the University of South Carolina were selected as the primary site for the bus demonstration and evaluation because of their prominence in fuel cell and hydrogen research.
- The HHB meets Buy America Requirements while utilizing fuel cells provided by Hydrogenics (headquartered in Mississauga, Canada) representing a great US/Canadian partnership for technology development and job creation.
The Hydrogen Hybrid Bus was deployed in August 2009 and is engaged in a two-year demonstration and evaluation project to prove the feasibility of advanced hydrogen-fuel-cell technology applications for mass transit. The demonstration and evaluation project will be conducted in three cities; Columbia, SC, Austin, TX, and Victoria, B.C. Upon completion of the BC Transit demonstration, the bus will return to Columbia to continue its evaluation as part of the University of South Carolina shuttle fleet.
Fire Safe Fusible Link Shut-Off Valves
BI-TORQ® Valve Automation has received Factory Mutual (FM) approval on its fusible link assemblies used in systems requiring automatic shut-off in case of a fire. These state-of-the-art assemblies prevent the spread of fire by containing flammable liquids or gasses once the API 607 (American Petroleum Institute) fire-safe certified valve automatically closes based on thermal release of a fusible link.
FM approval means that BI-TORQ® Valve Automation fire safe fusible link valve assemblies can help reduce insurance costs and allow factories to meet facility-wide safety certifications. With torque outputs ranging from 55 to 21,000, FM-approved fusible link assemblies can be used with fire safe ball or butterfly valves from ½” through 24″ line sizes. BI-TORQ® Valve Automation’s unique design allows for manual operation of most units even when the unit is armed, reducing the need for secondary valves.
API 607 fire safe approved valves can be customer-specified or provided by BI-TORQ® Valve Automation in carbon or stainless steel construction with NPT, socket weld or 150# ANSI flanged end connections. With valve seat choices in TFE®, RTFE®, TFM, PEEK and Delrin, BI-TORQ® Valve Automation’s fire safe valves are suitable for a wide variety of industries. Applications for these automatic shut-off assemblies include tank farms, petrochem, airport and truck refueling stations, paint and toxic chemicals, and biofuel operations.
Actuator Improves Plant Safety & Valve Control
Oil and water don’t mix. Neither do oil leaks and EPA regulations. At Florida’s City of Cocoa Charles H. Dyal Water Treatment Facility, this posed a problem. The accumulator system used for the hydraulic actuators contained more than 100 gallons of hydraulic fluid which frequently leaked.
The plant had been in the process of replacing the electrical actuators on its butterfly valves with Rexa electrohydraulic (Electraulic) actuators from Koso America. Carrying out a similar replacement on the ball valves resolved the leakage issues as well as improved reliability.
The city of Cocoa on Florida’s Atlantic coast provides potable water to all of central Brevard County, including its own 16,000 residents as well as those in nine other cities, the Kennedy Space Center and all the cruise ships sailing out of Port Canaveral. The water comes from a mix of surface and ground sources.
The butterfly valves at the Dyal plant had been designed to use electromechanical actuators, but over time these had turned into a maintenance nightmare.
Looking for a long-term solution to these maintenance issues, the plant installed an Electraulic actuator on one valve as a trial in 2005. These self-contained actuators incorporate hydraulic, electronic and mechanical technologies. There are two main components – the Electraulic power module and a control enclosure. They do not require an external hydraulic pump or tubing, but operate by moving hydraulic fluid from one side of a double-acting cylinder to another.
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| The self-contained actuators incorporate hydraulic, electronic and mechanical technologies. There are two main components – the Electraulic power module and a control enclosure. |
The power module contains a brushless DC motor, gear pump, flow match valve, and thermal expansion reservoir. Upon receipt of a control signal, the pump delivers oil at a nominal 2000 psi to one side or the other of a hydraulic cylinder, causing motion in the desired direction. Buyers can pick from four different sizes of motors depending on the pumping volume and maximum stroking speed desired. The two smaller units come with stepper motors, while the larger units use servo motors with faster frequency response. The hydraulic cylinders come in either linear or a rack and pinion rotary design. A position sensor is mounted within or adjacent to the cylinders and provides position feedback to the control electronics.
Within the control sub-assembly enclosure are the Central Processing Unit (CPU), power supply, and motor drivers. On the outside of the box (or inside it when conditions require) is a two-line display giving actuator status and a five button keypad used for set up and calibration of the actuator. The motor driver receives commands from the CPU and sends control signals to the motor – DC step pulses for a stepper motor or Pulse Width Modulated (PWM) DC voltage for a servo motor.
In operation, the CPU converts an incoming control signal to a target position and compares this with the current position as reported by the feedback assembly on the actuator. If the difference is outside the range preprogrammed by the user, the CPU will send a signal to start the motor. The motor then drives the reversible hydraulic pump to pressurize one side of the cylinder or the other, moving the piston in the desired direction. Once the desired position is reached, the pump shuts down and check valves close, locking the hydraulic fluid in the cylinder and maintaining the actuator position without having to keep the motor running.
Koso America makes a wide range of Electraulic actuators. The linear actuators come in sizes from 2000 lb thrust (8,896 N) to 600,000 lbs (2,668,933 N) with stroke lengths of .75″ to 120″ (2 to 305 cm). Rotary and drive actuators range from 600 lb/in torque (68 Nm) up to 800,000 lb/in (90,387 Nm).
Moving to a Standard Design
The City of Cocoa’s maintenance team installed the actuator, provided power and hooked it into the plant’s Intellution iFIX SCADA system. Bill Grabe, a sales engineer for Pro-Co, Inc. of Winter Springs, Florida, then came out to do the startup and calibration.
The Electraulic actuator passed its initial tests for performance and reliability, so the city decided to standardize on this design, installing new actuators on the rest of its butterfly valves, about 40 total, ranging in size from 16 inches to 36 inches.
Staff started replacing the actuators in 2008 and are now down to the last few small units. Some are two-position actuators while others are modulating. In most cases they were just installed on the existing valves. But, as can be expected at a 30-year-old plant, some valves needed replacement.
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| Rexa electrohydraulic (Electraulic) actuators from Koso America were installed at the City of Cocoa starting with a trial installation in 2005. |
Eliminating Oil Leaks
With the butterfly valves under control, Childers next started looking at the ball valves on the high-service pumps. The city has four of the master pumps and normally only one operates at a time. The four pumps, however, shared a single hydraulic pump and accumulator system (HPU) operating four shut-off ball valves (one for at the outlet of each pump), so a failure would shut them all down. In addition, it would create a reportable environmental incident, such as in early 2009 when gallons of hydraulic fluid leaked into the room and into the plant’s drain system.
The existing 24″ Pratt ball valves had been in service for the last 25 years and the controls associated with the master pumps were fairly elaborate and outdated. It was crucial, therefore, to replace these actuators without affecting the existing controls. It was decided that, rather than replace the scotch yoke actuators with rotary actuators, a linear unit would be sized to replace the existing linear hydraulic cylinder. This allowed the plant to leave untouched all the existing switches and controls.
An accumulator system with food grade oil (Envirologic 3100) was provided for each Rexa linear unit (Model X2L20000-22-C-A) so that even if there is a leak it does not pose an environmental problem. Each unit only requires 1.5 gallons of oil or a total of 6 gallons for all 4 units, a significant reduction over the older 100 gallon system. Additionally, since the actuators use a sealed closed loop system, the oil does not degrade like it does in conventional systems. This eliminates the need for filters and oil changes, resulting in considerable savings in maintenance expense and oil disposal fees.
In August, the first of the four actuators was installed with the rest completed over the next few months. Like the actuators on the butterfly valves, these are performing as expected, Childers said.
