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The following article appeared in the February 2007 issue of Power Transmission Engineering. Product NewsHaydon Switch and Instrument Releases New Catalog of Leadscrew Assemblies The new leadscrew assemblies include an offering of acme leadscrews, advanced coatings and anti-backlash nuts. According to the company's press release, these patent-pending designs not only eliminate backlash between the screw and nut, they also maximize system stiffness and minimize lost motion. Haydon offers five different nut styles, ranging from freewheeling, non-anti-backlash nuts to a user-adjustable anti-backlash nut. Leadscrews are available in diameters ranging from 1/8" to 5/8", and leads as fine as 0.012" up to fast leads as high as 1.25". All Haydon leadscrews are rolled from precision-ground 303 stainless steel. Leadscrews are also available with Haydon's unique Black Ice coating, a specially developed PTFE coating process, which eliminates flaking that commonly occurs with other PTFE coatings in today's marketplace. Haydon's anti-backlash nuts are made from a self-lubricating, polyacetal thermoplastic. Haydon's high-strength, freewheeling nut is made from a glass-fiber-reinforced polyester that offers high load-carrying capability and very high mechanical strength. In addition to the standard nuts, custom designed nuts and flanges are available. For more information: PCB’s Pressure Sensors Certified for Harsh Environments Series 102 and 121 pressure sensors are suitable for monitoring the performance of compressors, pumps, and gas turbines because they measure dynamic pressure events such as surges, pulsations, and spikes. These sensors also detect wellhead acoustics to determine properties of mud and water. Sensors may be used with ICP signal conditioning and permit the use of a variety of two-wire cable systems. The low-impedance signal may be transmitted over long cable distances, and the sensors may be used in dirty environments with no signal degradation. For more information: Danaher’s New Electronic Indexer Delivers Increase in Throughput “The Danaher Motion rotary indexer product set provides unmatched operational performance and flexibility, allowing OEMs to build a better machine, faster, and end-users to precisely assemble even the smallest of parts faster with far less scrap and better yield, while actually lowering the cost of ownership over the life of the machine,” says Dennis Gallagher, vice president of systems for Danaher Motion. “This solution enables users to achieve software-selectable motion sequences that run circles around mechanical indexer capabilities. Precision technology allows for superior repeatability to +/-1.2 arc-sec, with no backlash and system accuracy to +/-26 arc-sec. In comparison, mechanical indexers typically provide best-case repeatability to +/- 33 arc-sec and accuracy to+/-66 arc-sec,” he says. According to the company's press release, Danaher Motion's rotary indexer product set is programmed to go in any direction, at any speed, and at any angle. This feature is important to system integrators that deal with multiple product designs, including custom machines, as they are able to use a single indexer solution to satisfy any number of requirements. Additionally, should the demands of the manufacturing process change, this flexibility would allow end users to update the motion sequence to satisfy their application needs. This indexer product set can rotate both clockwise and counter-clockwise to achieve the shortest cycle time and increased throughput. Index times are programmable and no honing is ever required, as absolute position feedback maintains position, even under power cycling. Users should benefit from a noticeable 20dB reduction in system noise when compared with mechanical indexers. For more information: Stock Drive Products Introduces New Series of Timing Belt Clamps
These compact, lightweight clamps made from polycarbonate resin offer a solution for space and inertia concerns. According to the company's press release, these clamps accommodate single- and double-sided MXL (A 6M16M...), XL (A 6M 3M...), GT2 - 2 mm (A 6M51M...),3 mm (A 6M53M...), 5 mm (A 6M55M...) and HTD-3 mm (A 6M563M...), 5 mm (A 6M55M...) timing belts and are supplied with stainless steel assembly hardware. For more information: Allegro’s Two New Motor Drivers Designed for One or Two DC Motors The A3995 drive is designed for applications that have two DC motors. The 6 x 5 x 0.9 mm QFN package is designed for applications where PC board space is at a premium. The A3989 drive is designed for applications that have one DC motor and one stepper motor. The company also introduced the A8286 and A8292 dual LNB supply control voltage regulators that utilize the company’s BCD process. The low-noise block converter regulators (LNBRs) are monolithic linear/switching voltage regulators, specifically designed to provide power and interface signals to an LNB downconverter via a coaxial cable. The integrated boost switch has been optimized to minimize both switching and static losses. Voltage drop across the regulator has also been minimized. For more information: Rexroth’s New Drive System Contains Drive, Motion Control and Logic Control Mounted on the Motor The motor casing serves as the heat sink for the servo/control system, which is attached to the long axis of the motor, adding only a small amount to the cross sectional profile. According to the company's press release, this results in up to 30% less area required, compared to other integrated systems where the electronics are fitted behind the motor, and more than 50% less total space compared to a traditional servo system with separate motor and drive packages. Overall, this reduces the required space and air conditioning requirements of the control cabinet. In addition, a single cable carries both power and SERCOS communications. When several IndraDrive Mi systems are connected in series, the wiring costs are reduced even further. Instead of two cables running from the control cabinet for each axis, only one cable now is required. Each additional axis is daisy-chained to the preceding axis with pre-fabricated connectors. All connections, as well as the IndraDrive Mi itself, are rated to protection class IP65. The new IndraDrive Mi combines top power density with total functionality and is fully compatible with the IndraDrive range. As with all IndraDrives, these servo drives have over 100 technology functions, including the integrated Motion Logic system conforming to IEC 61131-3. The integrated concept of IndraDrive Mi eliminates the need to replace wearing parts such as fans, electrolytic capacitors and relays. Specialized electronics are designed to handle extreme temperature ranges, while providing more rated power than competitive solutions. For more information: Steinmeyer Miniaturizes Ball Bearings According to the company's press release, the new ultra-miniature ball screws are available in stainless steel with diameters as small as 3 mm and a choice of two pitches—1 mm or 0.5 mm. Steinmeyer now offers a range of miniature screws in stainless steel, from 16 mm diameter (with up to 30 mm pitch), down to 3 mm diameter. The products are manufactured especially for demanding applications in clean room, high-vacuum or corrosive environments. The screws are equipped with one of four types of ball nuts, with or without preload. By using Steinmeyer's internal ball deflector returns instead of external tubes, the nuts offer smooth, low-noise operation. Several standard lengths are included in the production program, complete with finished ends. Screws are manufactured from a 400 series stainless steel, hardened and then precision-ground to meet ISO tolerances from T0 to T5. All parts of the ball screw unit are manufactured from corrosion-resistant stainless steel including the shaft, nut, ball deflectors and balls For application flexibility, the miniature screws are offered with a choice of four nut types: • Series 1112—a cylindrical single nut with convenient attaching thread, available with play or preloaded using over-sized balls. • Series 1214—a compact, cylindrical single nut with fitting key, available with play or preloaded using over-sized balls. • Series 1412— a single nut with flange, available with play or preloaded using oversize balls. • Series 1510— a spring preloaded double nut, that effectively compensates for torque variations due to inaccuracies in the ground thread. The result is extremely smooth motion with near-constant idling torque—a critical requirement in many scanning applications. Applications for stainless steel miniature ball screws include semiconductor production machines and medical devices, including surgical robots and aerospace mechanisms. For more information: PowerJacks Offer More Precise Movement with Spring Coil Limiter A mechanical linear actuator or screw jack is frequently used for this type of application. Conventionally, these are best suited to lowering applications, as a simple elongated slot in an actuator's ram or clevis end allows the cover to be lowered into position and mate under its own weight by driving the actuator until the lifting pins are midway in the clevis slot. However, this method cannot be used to push a cover into position. Spooner Industries asked Power Jacks to solve this problem for one of their dryer hoods. For this particular application, a screw jack was the optimum solution. To push the cover into position precisely, Power Jacks designed a special coil spring load limiter for the end of the jack’s lifting screw. The load limiter consists of a helical coil wire spring, with squared ends held in place between two mounting plates. One plate is a restraining plate and the other a moving plate that is bolted to the cover structure. The spring is preloaded between the two plates so that the spring will not compress under normal working load when the cover is not in contact with its dead stops. When the screw jack drives the cover against a dead stop, the spring compresses over a normal working distance of 10mm. Within this “10mm window,” a limit switch is positioned to signal the machine’s control system to stop the screw jack as a positive stop position is reached. As the rate of compression of the spring is critical to the operation, each spring is custom designed for each application's specific requirements. In addition, for the device to work correctly, the spring assembly must remain stationary in its fixture. The screw jack was therefore fitted with a keyed lifting screw to prevent rotation. Two extra features were included on the screw jack to address safety concerns: 1. A rotation monitor to detect a jamming condition, consisting of a proximity sensor creating a train of pulses from a target ring that rotates with the gear wheel in the screw jack. The machine's control system can then compare pulse rates to determine a moving or stopped condition. 2. A secondary holding device for the lifting screw was provided by fitting a safety nut in series with the worm gear. This safety nut is not normally in contact with the lifting screw threads and is only engaged in the unlikely event that the trapezoidal screw thread on the gear wheel fails. To complete the unit for system installation, the screw jack’s lifting screw was fitted with a bellows boot cover, and a special flange-mount Neeter Drive bevel gearbox was used to connect the drive system to the screw jack at right angles. Since installation, the unit has worked successfully for Spooner Industries, which has now used several variations and models of the design up to 100kN screw jack capacity rating. For more information: R + W America’s New Couplings Designed for Power Transmission and Pump Drive Applications According to the company's press release, the plastic-to-metal interface between the coupling hub and the shafting allows for quieter operation than with metallic couplings. The hub material is a glass-fiber-reinforced polyamide developed for rigidity and corrosion resistance. Accelerated life testing involved 40 million load reversals at the coupling's rated torque. No change to the integrity of the coupling keyway was discovered, as the steel key itself was the more brittle and compliant of the two materials. R+W America says the thermal stability of the material is also critical, as an H7 shaft-fit tolerance for the hub must be maintained, regardless of the environments in which the couplings will be used. R+W TX couplings have an elastomer element that is press-fit between the two precision-molded coupling halves, resulting in zero backlash and guaranteed concentricity. The elastomer insert is available in several shore hardness values, allowing the designer to choose the level of damping effect. The TX1 series coupling is designed for a pure keyway connection and is molded or bored to customer shaft specifications. Shaft mounting is achieved via a keyway and a set screw. Sizes are available for torque capacities ranging from 2Nm (17.7 lbs/in) to 660Nm (5841 lbs/in), and bore diameters from 8 to 45mm and .375-1.75" with standard or metric keyways. For more information: |       | ||||
PCB Piezotronics introduced a series of dynamic, ICP pressure sensors that have been certified under ATEX and CSA for use in hazardous environments.
Danaher Motion introduces the rotary indexer product set. This fully programmable, direct-drive solution provides electronic indexing in a package that delivers increased throughput comparable to mechanical indexers and is maintenance-free over the entire life of the system.
Stock Drive Products introduced a new series of 16 timing belt clamps for long-span reciprocating synchronous drives.
Allegro Microsystems recently released three new products to the marketplace.
The IndraDrive Mi from Rexroth is a new motion control design concept.
The newest innovation from PowerJacks addresses an industrial machine's need to move a cover or lid onto a dead stop or sealing face. The movement must be precise, with contact on all dead stops or over the complete sealing face.
R +W America's new ECOLIGHT-TX1 series of molded thermoplastic insert couplings offer a reduced mass and moment of inertia, accompanied by a high level of chemical compatibility and tolerance for heat. The TX couplings are suitable for pump drives and other power transmission applications.