PRODUCTS BEARINGS & LINEAR MOTION WASTEWATER
PUMP BEARINGS Bearings have been supplied by SKF for a pumping system serving London’s Lee Tunnel. The 54-ton pumps will redirect as much as 2.9 million gallons of water per hour into the tunnel to protect the 150-year-old Victorian sewer network. They will be essential in preventing 39 million tons of sewage and storm water from overflowing into the River Thames every year. SKF spherical roller thrust bearings (29468 E) were used to support main thrust loads, with tapered roller bearings (32256 J2) supporting radial loads at the drive end of the shaft as well as any reverse thrust loads. Spherical roller bearings (24080) support radial loads at the impeller end of the shaft. The bearings help the pumps to
handle the loads and reliability demands of the application, the company states.
SKF
www.skf.co.uk Enter 220
MOTION SOLUTION WITHSTANDS THE AGGRESSIVE STONE CUTTING ENVIRONMENT
Based in Maidstone, Medway Marble manufactures and fits stone worktops, fireplaces and hearths. In the late 1990s, the company wanted to invest in a saw, but due to high costs decided to construct its own stone cutting machine. Looking around for a suitable linear motion system, owner Nick Browne realised the benefits of the vee bearing and track design of HepcoMotion products. The table-type stone
cutting saw was used for processing granite slabs up to 13
/4” thick using a
600mm diameter wheel. It featured two horizontal rails that facilitated a back and forth stroke of 2000mm. The only drawback was that airborne grinding dust would mix with coolant water from the cutting
heavy duty linear guide systems – used to move both the cutting head and sliding table. The vee guide systems are
tolerant of this as they have a self-cleaning action, which means
LINEAR PIEZO NANOPOSITIONING STAGES
With the travel and feedback options available, Aerotech’s QNP-L series linear piezo nanopositioning stages are suitable for applications ranging from microscopy to optics alignment. The stages are guided by precision flexures optimized using FEA to ensure high-stiffness and long life, offering stiffness and resonant frequency for high process throughput and fast closed-loop response. The design also provides unparalleled geometric performance while minimizing overall stage package size. The stages offer closed-loop feedback using a
capacitive sensor design that yields sub-nanometer positioning resolution and high-positioning accuracy (linearity). The sensor measures the output of the
positioning carriage, enabling superior linearity and positioning repeatability when compared to indirect feedback metrology techniques such as strain-gauge feedback. When coupled with Aerotech’s Q-series controllers
and drives, QNP-L stages demonstrate sub- nanometer positioning resolution and in-position stability (jitter), and high-positioning bandwidth.
Aerotech
www.aerotech.com
Enter 222 SRBS SUIT FOOD INDUSTRY DEMANDS
When investigating the most recent bearing failure on its spinach slicing machine, D’Arta found that over-greasing and water contamination of the existing plummer block bearing assemblies were to blame. During a meeting with Revolvo in which the SRB split plummer block bearings were demonstrated, it was clear that the design would reduce the time to change a bearing, while also allowing for greater heat expansion and a higher degree of axial movement. The solution saw the installation of four
complete bearing assemblies, suitable for the 100mm shaft diameter of the slicing machine, complete with a Walker sprung garter-seal arrangement to prevent the ingress of water. The compact SRB split plummer block bearings are interchangeable with standard SNL/SN/SD/SAF series plummer blocks. In addition, the ability to easily remove the upper section of the bearing makes for rapid
28 SEPTEMBER 2014 | DESIGN SOLUTIONS
visual inspection. Combined with the ability to compensate for a significant degree of shaft misalignment, the design can reduce maintenance time and help improve reliability. The performance of the new SRB
bearings at D’Arta resulted in evidence of a payback period of under eight months, along with improved reliability, which ensured that additional units
would be installed in other areas of the production facility. As part of the project, Revolvo also carried out on-site training for the maintenance engineers to demonstrate the ease of assembly and maintenance, as
well as assisting with the installation of the bearings and realignment of the motor and gearbox.
Revolvo
www.revolvo.com Enter 223
BLDC BG45 motor with integrated 4Q-servo controller, and can be easily programmed with multiple positions, speed and force. To ensure maximum application flexibility, the mounting of the linear drive can be selected for horizontal, vertical or overhead positioning with travel up to 1m available as standard in increments of 200mm – although longer stroke distances are available on request. It is suited to industrial and medical
automation applications which require fast, precise and smooth positioning.
Dunkermotoren Linear Systems
www.dunkermotoren.de
Enter 224 / DESIGNSOLUTIONS
wheel to form an abrasive paste, which would subsequently descend on the mechanics below. These included HepcoMotion GV3 linear motion/actuator and HDS2
that any contamination is wiped away by the vee bearings as they run along the rail. Similarly, any dirt that lands on the vee rail will eventually get wiped away. Of additional benefit, once the rail starts to show signs of wear it can be adjusted quickly to remove any play and restore the running quality back to its original condition, thus costing nothing in replacement parts. “The machine lasted for
more than 12 years, cutting granite every day, with only a little adjustment for wear and a re-grease every eight months or so,” said Browne. “I estimate that the machine cost around £7000 to make and
we recently sold it for £5000 after all those years.”
HepcoMotion
www.HepcoMotion.com Enter 221
LINEAR ACTUATION
Now available from Dunkermotoren Linear Systems is the LPA08 linear positioning actuator. This features a lightweight yet robust, ball-bearing mounted lead screw, and is powered by a compact brushless DC motor with integrated positioning controller. The feed movement, which is designed for loads up to 20kg, maximum axial forces up to 150N and adjustment speeds of up to 0.6m per second, is driven by a Dunkermotoren
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