Misumi Now Offers Comprehensive Line Of Couplings
MISUMI Coupling types include high precision Single Disc and Double Disc Clamping models, many of which may be used with servomotors. Also offered are Oldham, Slit and N Couplings, as well as Jaw, Sleeved, Bellows, and Resin types, in a variety of sizes and configurations.
The SCXW is a Double Disc type precision disc clamping coupling with high torque but no backlash. Its torsional rigidity is up to 26% higher than conventional (standard) disc clamping couplings. It suits applications requiring fast positioning precision. All the bolts are trivalent chromate plated and suitable for use in clean environments.
The MFJGWK is available as a high rigid Oldham coupling, set screw type. The MFJCGWK is a high rigid Oldham coupling, clamping type. Both products feature an aluminum bronze spacer and have a keyed bore. These couplings have allowable torque 2X higher compared to resin spacers.
The SCOC is a short Oldham coupling, clamping/spacer type. This space-saving version works with miniature devices because it is 17% shorter than conventional types.
Most MISUMI Couplings ship in six days, with the exception of the new High Rigid Oldham Couplings, which ship in eight days. Some couplings offer optional express shipping for faster delivery.
MISUMI USA, Inc.
Http://us.misumi-ec.com
Servo Couplings Use Dampening Attributes For Vibrations
August 10, 2010 by CouplingTips
Filed under Servo
Specialist mechanical components supplier, Ondrives Ltd of Chesterfield, England have recently introduced a high quality range of servo-insert couplings into their extensive coupling range via their biggest ever catalogue, now that they have merged with sister company, Rino Industries Ltd.
Typically, they are used in applications where vibrations and crushes may appear. The dampening attributes of those couplings are caused by the spider element which is positioned between the two hubs. This spider element is available in different shore hardnesses. Depending on the requirements it is recommended customers use a spider element with low dampening properties for applications with low vibrations and crushes (higher torsional stiffness of the coupling) and to use a spider element with high dampening properties for application of high grades of vibrations or crushes (lower torsional stiffness of the coupling).
A further positive property of the servo insert couplings is that they are pluggable, so they can be assembled quickly and easily even under difficult assembly conditions. The many different varieties of the hub style include shaft fixing with set screws, with clamp hubs and with outer conical hubs. Customers will find that the most popular type, as always, is with the clamping hubs as they ensure the fastest assembly/disassembly without leaving marks on the shafts. Torque range varies from as low as 1.2Nm up to 940Nm on the largest sizes. Other advantages include an extremely compact design and minimum mass and inertia as standard. They offer high resistance against environmental influences and temperatures as well as being non-wearing and therefore maintenance free.
A misalignment of the shafts in axial, lateral and angular directions can be compensated by a servo insert coupling as well but it should only be a minimum of misalignment because relatively high reset forces are caused by the coupling which do negatively influence the lifetime of components such as bearings in this environment, the company states.
Typical applications include -
Stepping motors, servo drives, machine tools, CNC machines, wood working and packaging machines, factory automation machinery, printing machines, sheet metal forming machines, industrial robots, textile machines and control and feedback control systems.
GERWAH® Product Line
May 24, 2010 by llangnau
Filed under Bellows, Disk, Elastomer, Flexible, Industry News, Miniature, Safety, Servo, Torque Limiters
The GERWAH® line of products consists of magnetic couplings, metal bellows couplings, servo-insert couplings, line shafts, RING-flex® couplings and safety couplings. These couplings are available in a range of sizes and torque capacities to 3,800 lb-ft. The low mass of the lightweight construction helps increase machine performance and reduce energy costs.
Ringfeder Power Transmission USA Corporation markets a range of power transmission components and keyless shaft/hub technology. Other power transmission products include shock absorbing devices, flexible elastomeric couplings, flexible disc couplings and torque limiters along with other specialty and custom made products.
RINGFEDER
Low Inertia Aluminum Couplings Reduce Cycle Time
The aluminum CD® model is a low inertia, lightweight coupling with high torsional stiffness for servo motor applications. It is available in single and double flex versions.
“We surveyed design engineers to find out what was the most desirable feature when specifying couplings for servo motor applications,” reports Robert Mainz, Zero-Max sales manager. “Low inertia was the most important.” These engineers said they continually look for ways to reduce cycle time and improve system productivity. A lightweight yet high strength coupling design will let you increase the speed of the actuator. Lightweight couplings will also have an effect on the energy consumption in their designs.
The working part of the CD® coupling is made of a special composite material. The composite disc design withstands the stresses of a servomotor’s high acceleration rates and high torque capacity better than other coupling designs. This results in lower energy requirements, and longer life of the motor and other operating components while ensuring uninterrupted system operation.
Zero-Max CD couplings are available in single and double flex models with or without keyways. The double-flex version is for precision applications requiring misalignment capacity greater than the single flex design. The single flex models have a torque capacity range from 40 Nm to 1436 Nm and beyond with speed ratings from 4400 RPM to 17,000 RPM.
Zero-Max
www.zero-max.com
Six factors to remember about couplings in a motion system
Physical values such as torque, torsional rigidity, spring stiffness, moment of inertia, imbalance, and zero-backlash play a major role in coupling design. Here are a few facts to keep in mind when you design your motion system.
Torque (Nm): is the product of an acting force and the effective length of the acting force’s lever arm.
T = Fxr
T = Torque (Nm)
F = Force (N)
r = Lever arm (m)
With a force of 100 N and a 1 m long lever arm, you can generate a torque of 100 Nm. Or, you can generate a torque of 100 Nm with a force of 1000 N and a 0.1 m long lever arm. For couplings, a specific amount of torque can be achieved with a large outer diameter of the coupling and a correspondingly low acting force or with a small outer diameter and a correspondingly high acting force.
Torsional rigidity (Nm/rad): refers to the rigidity of a coupling when it is subjected to a torsional load. If the torque exceeds the maximum torsional value of the coupling, the coupling will no longer be strong enough to transmit the acting rotational force. Ex: If a coupling with a torsional rigidity of 10 000 Nm/rad is subjected to 10 Nm, the connection element will twist by 1/1000 rad. That is equal to an angle of twist of about 0.057 degrees (1 rad = 57°17’44.8”). For a torsionally rigid or vibration damping coupling, this angle of twist may still be within the admissible range. In practice, torsionally rigid couplings normally have a maximum angle of twist of less than 0.05 degrees and vibration damping couplings have a maximum angle of twist of less than 5 degrees.
Spring Stiffness (N/mm): is the counterforce exerted by the coupling in case of differentiated position of the axes in an axial, radial, and lateral direction. Ex: If the axial spring stiffness of a coupling is 30 N/mm, the coupling will exert a force of 30 N in the case of an axial displacement of 1 mm. These forces are important in a design with couplings, particularly when selecting bearings or other drive system components.
Moment of inertia: is the moment resistance when the rotational speed is changed. Normally, the lower the total weight and the smaller the outer diameter of the coupling body, the lower the moment of inertia. The reverse is also true, the higher the weight and larger the outer diameter, the higher the moment of inertia. This feature is important in highly dynamic applications because the drive has to generate sufficient torque to overcome a body’s moment of inertia to accelerate and decelerate.
Imbalance: in a drive system, imbalance should be as low as possible for smooth operation. Caused by asymmetries in the drive system where mass is distributed unevenly, it affects centrifugal forces on the entire drive system. It can be rectified by “balancing bores,” which are normally drilled directly into the location of the disproportionally high concentration of mass.
Zero backlash: is a lack of empty space or “play” when the rotational speed, direction of rotation, or torque changes. It does not mean that there is no angle of twist. Backlash is an important factor in predicting bearing life.
Information courtesy of R+W America
ServoClass® Couplings deliver high torsional stiffness
March 25, 2010 by llangnau
Filed under Featured, Industry News, Servo
ServoClass® Couplings suit applications using ac and dc servomotors that need precise positioning and the ability to handle high reverse loads. These couplings have zero-backlash and low hysteresis.
Three new sizes have been added to the ServoClass coupling line. They handle bore diameters from 0.875 in. (20 mm) to 1.378 in. (35 mm) and operating torque from 3937 to 9843 lb-in., (100 to 250 Nm). Additional sizes are available starting with the smallest bore size 0.157 in. (4 mm) and larger.
All ServoClass couplings are manufactured of RoHS compliant materials. They are lightweight and designed with 304 stainless steel disc packs and 7075-T6 aluminum hubs and center members. They are available in single and double flex models in inch and metric sizes. All models and sizes feature clamp style hubs with corrosion resistant socket head cap screws.
“ServoClass couplings provide a better option compared to beam or bellow style couplings,” reports Robert Mainz, Zero-Max sales manager. “As the cycle becomes faster, they outperform beam couplings, which experience harmful windup. Their robust design also outperforms the fragile design of bellows couplings.”
Zero-Max
www.zero-max.com
How to Properly Choose Servo Couplings
November 2, 2009 by CouplingTips
Filed under Servo
R+W Coupling Technology recently proposed a system on how to properly select your servo couplings. They state that servo systems require mechanical components with high torsional stiffness in order to perform properly in applications requiring rapid acceleration and deceleration of high inertia loads. Flexible couplings usually have the lowest torsional stiffness of any component in a motion system. Couplings are often selected based on factors other than torsional stiffness, often to the detriment of system performance. Proper servo coupling selection can pay off when considering the overall picture.
R+W also say engineers go to great lengths to ensure that inertia mismatch between the load and the servo motor is compensated for. Motors and gearheads must be selected in order to ensure the ability of the drive to be able to accelerate the load with ease. The mechanical connection between the drive and the load can however unvaryingly compromise the efforts of the drive system. The most compliant component in the mechanical system (e.g. the coupling) will be twisted back and forth by the settling motion of the load at any major velocity change. The formula provided by R+W for calculating torsional deflection based on load and stiffness is as follows:
 |
f | = | torsional deflection (degrees) |
| TAS | = | peak torque (Nm) | |
| CT | = | torsional stiffness of coupling (Nm/rad) |
Depending on the inertia of the load and its effect on peak torque, this can happen to varying degrees. In any case, more power is required in order to accelerate the load at the desired rate when a less rigid component is installed between the drive and the load. According to R+W, this may or may not pose a concern depending on the application, and tends to be of higher importance in cases with a high inertia load that must be rapidly indexed.
When tuning servo drives, R+W claims that velocity and position feedback loops must be set to a low enough frequency so as not to excite the most torsionally compliant component in the system by reaching its natural frequency. Higher coupling stiffness leads to a higher natural frequency of the entire system, which means that feedback loops can be set to a higher frequency. This leads to a faster moving, more accurate machine, and ultimately higher throughput and higher quality.
A commonly used calculation by R+W for determining required coupling stiffness, and / or maximum drive frequency, utilizes what is called the “two-mass system.” In practice, if the calculation is carried out based on coupling stiffness alone, the calculated resonant frequency of the load has to be at least twice as high as the excitation frequency of the drive.
 |
fe | = | Resonant frequency of the system (Hz) |
| CT | = | torsional stiffness of coupling (Nm/rad) | |
| JL | = | Moment of inertia, load (kgm^2) | |
| JA | = | Moment of inertia, drive (kgm^2) |
Bellows couplings quite simply posses the highest torsional stiffness of commercially available flexible couplings, and are considered by many to be the standard for servo applications. Hydroformed from a continuous tube of stainless steel, bellows can easily flex laterally, angularly, and axially with only very gentle restoring forces, while remaining highly rigid in rotation. This, paired with a low moment of inertia, according to R+W, makes bellows couplings appropriate for almost any application requiring optimum efficiency and performance in acceleration and positioning.
The exception lies, says R+W, in cases where neither a high level of dynamic positioning accuracy, nor the ability to optimize servo loop gains is critical. A vibration damping coupling can be a very dependable and a low cost alternative in these cases. When pushing the limits of efficiency, accuracy, and speed, the most torsionally rigid coupling possible should be used in order to design the best servo system possible.
http://www.rw-america.com/index.php
High Torque Servo Couplings
July 6, 2009 by CouplingTips
Filed under Servo
Heavy duty torque ratings and high strength conical clamping hubs make BK3 couplings the choice for high torque servo gearboxes. Manufactured with a double-walled stainless steel bellows to absorb parallel, angular and axial shaft misalignment, the BK3 has an extremely high torsional stiffness to complement its relatively very low moment of inertia – allowing it to handle rapidly indexing and reversing servo applications.
These unique couplings are manufactured with a tapered conical clamping element, which results in the highest shaft clamping forces, without keys, compared to any other hub design. The BK3 coupling also incorporates unique disassembly screws to aid the mechanic in tight spaces.
The clamping sleeves are custom bored on each side for shaft diameters from 10 to 80 mm ( 0.39 to 3.13 in.). Sizes are available for torque capacities ranging from 15 to 10,000 Nm (133 to 88,500 in. lbs.).
R+W America
www.rw-america.com
Low-Cost EKC Servo Couplings from GAM
June 16, 2009 by CouplingTips
Filed under Servo
Mount Prospect, IL, USA – GAM introduces a complete range of low-cost elastomer couplings, the EKC Series, that combine high precision and custom configurability with an economical price. Starting at $34, these couplings contain all the features you would expect with other precision couplings from GAM.
The EKC Series is engineered to minimize space requirements as well as design and installation time. Key features of the EKC Coupling include a single bolt radial clamping hub, star-shaped elastomer element with involute tooth profile, and high shore hardness to ensure zero backlash over the life of product. Utilizing the EKC provides compensation for small shaft misalignments and oscillation resonance is dampened. The couplings are both cast and machined and offer same day delivery.
GAM
www.gamweb.com
Hydraulic Pumps Benefit From Zero-Max CD® Couplings
February 27, 2009 by R. Nelson Parrish
Filed under Servo
Plymouth, Minnesota: New CD Couplings® from Zero-Max are an ideal choice for use with fixed displacement hydraulic pumps driven by servo motors. CD Couplings provide the ideal combination of high dynamic load capacity and high torsional stiffness to ensure reliable system operation.
“This new pump drive technology has become increasingly popular because of dramatic improvements in their energy efficiency and noise reduction”, reports Robert Mainz, Zero-Max sales manager. “These pump systems utilize the power and precision that only a servo motor can provide. The system pressure is controlled by modulating the output volume of a fixed displacement pump. This is made possible utilizing a high performance control system and the high performance qualities of a CD shaft coupling.”
CD couplings have unique design qualities that are robust to ensure that these hydraulic pump applications are reliable and productive. CD Couplings are designed so that the working part is made of a composite material. The composite disc design withstands the punishment and stress of a servo motor, “everything a variable speed pump drive system can dish out,” report OEM designers. They also report that CD couplings enable these systems to not only perform well in test lab environments, but more importantly, on the production floor.
CD Couplings are available in single and double flex aluminum hub models with or without keyways. The single flex models have a torque capacity range from 40 Nm to 1436 Nm and beyond with speed ratings from 4400 RPM to 17,000 RPM.
All CD couplings are environmentally friendly and are manufactured of RoHS compliant materials.
For more information, call 1-800-533-1731 for FREE brochure. Outside US and Canada, call 763-546-4300.
