|Abssac Newsletter : October 2012|
The scientist Blaise Pascal formulated the principle of pressure propagation in liquids many years ago: Pascal's law or the principle of transmission of fluid-pressure states that , “pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure ratio (initial difference) remains the same”. The ETP product utilises the many positive qualities of this principle and has continued to develop it further so that it can be utilised reliably and accurately within industrial applications.
All ETP products consist of a double-walled hardened steel (in some cases stainless steel) sleeve, filled with a pressure medium. In the product flange there are one or more screws and a piston with seals for the pressure setting. When the pressure screw is tightened an even and moderately high surface pressure is created against the shaft and hub, causing the locking effect. The self-contained product allows this procedure to be repeated many times.
Whether the hubs are to be removed or repositioned, mounting and dismantling is done in less than a few seconds. The hydraulic principle gives immediate advantages for today´s modern machines. The compact designs also ensure better concentricity and balance at increased machine speeds, shorter downtime for service and increased precision. The ETP products now available through Abssac Limited are chosen for more and more mechanical designs.
Where we win……
• The Quick and Easy clamping of shafts
Machined torsion springs can provide very precise, linear deflection rates because virtually all-residual stresses are eliminated. The stress found in machined torsion springs is dominantly a pure bending stress providing a more reliable and accurate part.
Most wound torsion springs can achieve a rate of around 15%, the machined alternative can easily achieve 10% on rate and can be tuned to +/-2% for the more demanding applications..
We like to think of it as ....Precision Elasticity...
The most common machined torsion spring configuration is the single start spring, which consists of a single continuous coil element, which starts at one end and terminates at the other end, much like its wire wound counterpart. We can supply both unwind and wind up torsion springs and in both cases the spring rates achieved are as linear as the geometry will permit.
However, it is not only the accuracy of rate which is an advantage, since the part is machined, we can incorporate any form of end attachment into the torsion spring. It is important to remember that we can supply an attachment integral to the machined spring that allows the PURE MOMENT to be resolved.
In the wound torsion spring format, tangs are produced by bending the last portion of wire into a set position. These tangs are bent inward or outward upon which a force can be applied.
This not only limits the actual attachment designs available but induces high stress into this attachment area. In the machined torsion spring the tang is integral and without stress making it a far more rugged and reliable attachment.
Why not call Chris Cattle with your machined spring questions…
Cold rolled formed lead screws are proving to be a superb economical solution for linear applications requiring repeatable accuracy and reliability. Using a comprehensive range of screw diameters from 3mm through to 24mm, Abssac can match performance and function by offering the capability to supply custom thread forms and combining them with a range of proven anti-backlash or standard nuts designs. The nut designs are then enhanced to incorporate bespoke attachments, in many cases amalgamating parts of the traversing mechanism into the final design.
Whether it is a fine or coarse pitch thread, the end result is a high integrity lead screw and nut product that is ready to be fitted directly into the application.
Phil Jones at Abssac states “We like to pride ourselves at Abssac on our excellent product knowledge for precision miniature motion designs, which are not only excellent quality but also competitively priced”.
Shaft couplings for the printing industry are required to work with absolute precision to guarantee a register pressure and therefore ensure a high print quality. The high precision requirement starts in the actual printing mechanism and continues through the refinement process to quality assurance on the final product. To maintain the precision movement the Schmidt-Kupplung range of shaft couplings are utilised in many areas of the printing processes. For example, in the drives for printing mechanisms the shaft couplings can be found driving ink rollers and duct rollers or in the drives for rotary die cutting machines and cutting rollers they can be found where guaranteed precise stamping or cutting processes are performed. Driven equipment is also commonly required to be axially displaced during operation and it is this displacement that can be disproportionate to the DBSE (distance between shaft ends) in the printing machines.
Other designs of shaft couplings simply cannot accept such large parallel shaft offsets, without requiring a much longer DBSE. In addition, other coupling designs may suffer from a degradation of torque capacity and increased backlash during operation when required to accommodate such a high degree of parallel offset. The Schmidt-Kupplung allows for this exceptional axial movement whilst reliably transmitting backlash free torque. Most importantly, the Schmidt-Kupplung delivers all these advantages in an extremely compact design. For example it is possible to have a parallel shaft offset of 275mm in an overall length of 284mm ! (Offset Plus V3300 series)
Another unique advantage of the Schmidt-Kupplung is that during the printing operation, individual rollers may also need to be adjusted, replaced or even removed from the machine. Ease of connection and the unique properties of the Schmidt Kupplung design allow for the axial displacement of roller holders up and away from the press so that maintenance or roller change can be carried out. There is no need to stop the printing machines at this time.
The use of precision couplings from the Semiflex range are employed where very high output and productivity are required. High torque and high speed are easily catered for with the Semiflex range of shaft couplings. At Abssac we can also offer customer-specific couplings from the Semiflex range in areas such as the axially guided cutting rollers.
Another perfect use of the Semiflex coupling is during offset printing. The printed sheet is subject to a continuous visual check via Densitometric sensing which allows for the quantitative measurement of optical density in light-sensitive materials, such as paper. The antibacklash features of precision drive coupling ensure that the individual measuring points are exactly achieved. Shaft couplings from the Controlflex range are utilised in a typical drive for a travelling sensor head where less torque but high torsional stiffness and zero-backlash rotation is required.
For further details please contact our sales office who will be more than happy to discuss your applications.
As the name suggests, the range is aimed at the more industrial type application with dynamic load capacities from 900 to 13449 kgf being catered for. Utilising the recirculating ball bearing nut technology as the base of the product, the Industrial class ball screws encompass screw diameters from 16mm up to 80mm as standard. In many cases multiple ball circuits, per ball nut, are employed to achieve greater load capacities making the product suitable for many types of application. Whatever the load, it will be delivered with both high efficiency and low drive torque. Stocked screw lengths of up to 4500mm are available up to 32mm diameter and screw lengths up to 5600mm long for screws above 40mm in diameter on request. Offering the Industrial ball screw range converts rotary input into precise linear movement. All industrial ball screws can be delivered cut to length and if required, machined ready to fit into the required support bearing mounts.
Put simply, the rolling process forms a thread for less cost than a ground one. Available in diameters from 4mm to 14mm with various leads. Ball screws that have been cold rolled formed are ideal for applications that do not require the absolute finite accuracy of the ground ball screw equivalents. However they do reliably transmit a linear load with a high degree of accuracy. Accuracies of C7-20 (That's 52microns per 300mm of cumulative lead accuracy of 20 microns of axial backlash) can be faithfully delivered.
Whether your requirement is for a precision rolled or ground ball screw, Abssac can assist you in specifying the right part for the application.
Our knowledgeable staff are always available to help you choose the correct ball nut and the diameter and lead of the ball screw that best suits the application. Where necessary we can also deliver a very cost effective end journal machining facility allowing the parts to be delivered ready to fit into the application. This solution can eliminate your potential scrap rates. At Abssac, we welcome the opportunity to develop linear solutions within tight cost budgets.
Stocked pre bored from 6mm to 60mm. Complete with standard keyways. Stocked solid hubs versions. Rated from 10Nm up to 665Nm. Choice of spider elements dependant on torque requirement. Larger sizes available on request.
Engineers from both ETP Transmission and Schmidt Kupplung will be in attendance to discuss products and applications with you.