|Abssac Newsletter : October 2013|
A solution looking for a challenge
Many engineers come across the familiar problem of shaft misalignments within driven shaft applications. In some cases the parallel offset of the shafts are above and beyond the capabilities of standard shaft couplings and can often result in punitive drive shaft length, or elaborate mechanical solutions to move driver and driven shafts in unison, to overcome the offset.
The Schmidt-Kupplung is a compact, torsionally stiff performance shaft coupling that compensates for variable parallel shaft offset without side loads during operation. The extreme shaft offset capability combined with a small D.B.S.E. (distance between shaft ends) makes the Schmidt-Kupplung quite unique. Interestingly, its modular construction allows both torque transmission and radial offset capacity to be optimized for each application. For example it is possible to accommodate a parallel shaft offset of 275mm in an overall shaft coupling length of 284mm! (Offset Plus V3300 series). No other shaft coupling design can provide the parallel shaft offset to overall length ratio.
Transmitting torque ranges from 35 Nm to 6610 Nm through needle bearings with internal lubrication, the well-balanced design reliably transmits torque and has been successfully utilised in applications such as woodworking machines, roll forming machines, high quality printing machines, packaging machines and paper manufacturing machines.
In fact the unique design can be utilised in any transmission design where high torque, high shaft offset and small DBSE is present.
Peter Wright, the Schmidt Kupplung sales engineer at ABSSAC says “Engineers needn’t reinvent the wheel with their transmission challenges. There are even 2D and 3D CAD format drawings available for all model types.”
Abssac LEAD's the way....
As one of the only suppliers on the market to truly offer a miniature lead screw product, Abssac overcomes significant technical obstacles and once again manages to supply what other lead screw manufacturers cannot.
With well over 30 years' experience a recent application used a 3mm and 2mm diameter stainless steel trapezoidal thread form, both with a 1mm lead. The precision drives also included bespoke nut designs which accurately translated rotary to linear motion. The nuts were machined from Turcite and incorporated unique attachment tangs. Turcite was suggested as the nut material for its self-lubricating characteristics. The final parts measured 30mm and 20mm in length and were supplied complete with machined end journals for motor and bearing connection. Abssac was able to supply the parts on budget and have exceeded reliability and performance demands set by the customer.
Abssac has expanded its lead screw ranges to incorporate the machining facility to supply any type of thread form that you may require. In fact Abssac can supply screws up to 120mm diameter and up to 5 meters long can also be supplied. Combine this with the ability to offer further journal end machining, gun drilling, screw hardening and special coating treatments, gives Abssac the competitive edge.
Combined Compression and
The spring unit should compress and extend 2mm but deliver an accurate spring rate over a set life time. The current wire wound spring was not providing an accurate spring rate over time and each spring had to be rate tested and certified before fitting. Normal rate accuracies were ranging from +/-15% and were not linear in rate.
As the name suggests, the machined spring is machined from a single piece of material. This not only allows one, two, three or more spring elements to be machined into the single part but due to the geometry of the coil, the spring rate is totally linear. In fact spring rate tolerance can be as good as +/- 1% if required with the machined spring.
After the preliminary discussion between the customer and our application engineer, a drawing of the concept spring was forwarded to be reviewed. A few minor changes were then needed, as the customers engineer looked into incorporating attachment designs into the single piece stainless steel spring. All other dynamic parameters could be improved on over the wire wound spring
being used and a final configuration was then proposed.
Two test samples were sent to verify the installation and complete life testing. The machined spring supplied improved efficiency of the application, reduced parts inventory and each spring supplied was certified on rate so could be fitted straight into the application.
Solving this project has led to several other spring applications of the same physical configurations, but with varying spring rates and materials.
For further information on our unique machine spring product why not give Chris Cattle a call on 01386 421005 and ask for our free demonstration box.
ETP Hub Shaft connections improves productivity in rotary PET bottle stretch blow moulding machine
The ETP shaft connection solution is designed to allow the user to tighten or loosen a single cap screw to allow the quick and easy mounting and dismantling and if necessary incremental repositioning of the hub on a shaft.
An excellent example of this products placement is in the production of PET bottles. This highly competitive business uses the stretch blow moulding process, which depending on the type of machine can have from 4 up to 36 blow moulds per machine; thus the output of the machine can range from 8,000 up to 72,000 bottles per hour.
Preforms of the bottles are inserted into the blow moulding machine via a conveying system. The machine consists of a linear heating module or preform heating and a blow-moulding module in which the heated preforms are blow-moulded into bottles.
The preforms initially pass though the heater to achieve elasticity. Next step is the transfer of the preforms into the blow moulds. To fasten and centre the transfer wheel an ETP-EXPRESS is used. The single screw design enables quick and easy mounting and adjustment which is a key benefit
The rotary blow mould machines are often recognised within the filling and packaging industry for their unmatched efficiency, and in key applications ETP is increasingly forming an important part of the design.
Magic Carpet fix
Another shaft coupling connection challenge was successfully solved by the Heli-Cal flexible beam product available through Abssac Limited.
Abssac's customer had an application where a precision encoder was being connected to a carpet manufacturing machine output shaft. The machines are used to manufacture man-made fibre twisted loop pile carpets for domestic use.
If the vibration and movement present at the output shaft was transmitted to the encoder, it would cause signal errors and ultimately prematurely destroy the encoder. Ultimately this would lead to below standard carpet being produced due to loom operational irregularities. Whilst very little torque was required in the application, torsional stiffness and zero backlash were important design parameters. The customer also wanted a low maintenance solution.
From a coupling design aspect, the application required large axial motion and parallel misalignment because of the assembly tolerances. The customer was originally using a multi-part bellows shaft coupling, but the required angular and axial movements lead to premature failure. Additionally, under certain operating conditions, the bellows coupling allowed too much vibration to reach the encoder.
The solution was found using an adapted Heli-Cal flexible beam shaft coupling. A low inertia Aluminium part was created using two flexible beam elements in the single piece design. Two integral clamps held the shafts, each flexible element allowed for the maximum angular and axial offsets set by the customer but also maintained a high degree of torsional stiffness. A “no charge” working sample was then sent for test and evaluation. Testing proved very successful and verified the new Helical coupling design provided better isolation of the encoder from the motor and better performance. Subsequent machines are now being fitted with the low cost, long term solution.
If you have a shaft coupling parameter that is outside of the normal standard shaft coupling capability Abssac may have the solution you require.
Specifying the right flexible shaft coupling for an application can be a technical challenge for the engineer, particularly as there are also so many designs on the market. Shaft size, torque capability, angular and parallel shaft misalignment, not to mention material and attachment, all add to the myriad of parameters that narrow down choice.
At Abssac, we pride ourselves on our experience in the specification of shaft couplings whether they are miniature or
Industrial. We have a 30 year plus supply chain behind us, to ensure correct product specification. Whether a retrofit part or a new application, our engineers can help you ensure the product choice is right. In many cases our engineers have worked closely with customer engineers to optimise shaft coupling designs.
Perhaps the next time you have a rotary shaft coupling application or just reviewing your current suppliers why not give Abssac a call.
90mm diameter screws delivered to water filtration plant
Using an existing damaged screw for dimensional information, Abssac replicated 14 screws which were a massive 90mm diameter by 2 metres long. Weighing over 100kg each and using a basic trapezoidal thread form satisfies another Abssac customer.
A toothpaste factory had a problem. They sometimes shipped empty boxes without the tube of toothpaste inside. This challenged their perceived quality with the buyers and distributors.
Understanding how important the relationship with them was, the CEO of the company assembled all of his top people. They decided to hire an external engineering company to solve their empty boxes problem. The project followed the usual process: budget and project sponsor allocated, RFP, and third-parties selected.
Six months (and £60,000) later they had a fantastic solution - on time, on budget and high quality.
Everyone in the project was pleased. They solved the problem by using a high-tech precision scale that would sound a bell and flash lights whenever a toothpaste box weighed less than it should. The line would stop, someone would walk over, remove the defective box, and then press another button to re-start the line. As a result of the new package monitoring process, no empty boxes were being shipped out of the factory.
With no more customer complaints, the CEO felt the £60,000 was well spent. At the end of the first month, he reviewed the line statistics report and discovered the number of empty boxes picked up by the scale in the first week was consistent with projections, however, the next three weeks were zero! The estimated rate should have been at least a dozen boxes a day. He had the engineers check the equipment and they verified the report as accurate.
Puzzled, the CEO travelled down to the factory, viewed the part of the line where the precision scale was installed, and observed that just ahead of the new £60,000 pounds solution sat a £20 desk fan blowing the empty boxes off the belt and into a bin. He asked the line supervisor what that was about.
“Oh, that,” the supervisor replied, “Bert, the kid from maintenance, put it there because he was tired of walking over, removing the box and re-starting the line every time the bell rang.”
Jaw dropping prices.....
The Jaw style shaft couplings from Abssac are a low cost, no fuss flexible shaft connection...
The curved jaw coupling design consists of an elastic 'spider' and two hubs. The spider utilises advanced polyurethane materials to provide reliable torque transmission as well as dampening of impulse loads. With a selection of spiders to choose from allows the user to customise the jaw coupling's performance. Selecting a soft spider material will give the jaw coupling the greatest dampening characteristics, whilst a hard spider will
provide the greatest torque capacity.
Hubs are available in cast Iron or Aluminium and all hub sizes are stocked with bore and keyways to suit shaft sizes from 6mm to 60mm (Or pilot bored). The Jaw couplings are rated from 10Nm up to 665Nm and are a direct replacement to other industrial jaw couplings.
Larger sizes are available on request. Why not give Stacey a call to ensure correct product selection.
Enterprising Lead Screw Supplier
Are you looking for a lead screw supplier that can produce exactly what you want? Or perhaps you have an old acme screw that needs replacing but have no technical drawing specifications to work from. Abssac can help.
The company has expanded its lead screw ranges further incorporating the machining facility to supply any type of thread form that you may require. Most common thread forms are the acme or trapezoidal but Abssac can now supply multi-start or special threads profile requirements.
The image opposite shows a 1000cm length of 40mm diameter by 7mm pitch 316 Stainless Steel, trapezoidal thread form. Unusually, the screw had both a left and right hand thread matched to a high degree of linear accuracy on the same shaft. The final assembly was supplied complete with bespoke flange mount bronze nuts for marine use.
Abssac has well over 30 years' experience and can also supply auger mixing screws and self reversing screw formats. In addition to the range of lead screws a complete range of plastic, steel or bronze nuts are available, which are tapped and matched to the screw supplied. The leadscrews can be supplied in a machined, rolled or whirled format, using steel, stainless steel or in some cases aluminium or bronze.
Combine this with the ability to offer further journal end machining, gun drilling, screw hardening and special coating treatments give Abssac the competitive edge.