Occasionally, even clamping tools, which are usually employed in production, are used to fix parts. These exert clamping forces that are far too high for the surfaces with fine finishes. In an emergency, some inspection technicians resort to Plasticine or even chewing gum to hold parts in place. Clamping tools designed specifically for the measurement sector, such as those offered by dk, provide a far better alternative.
The south German company dk has, for more than 25 years successfully provided an extremely large, tried-and-tested clamping system for measuring technology under the brand names of SPANNFIX, QUADERFIX, SCHIENENFIX and MICROFIX.
High clamping forces are expected of clamping tools that are used in machining. As a rule, the closer the part being machined is to its final dimensions, the lower the clamping forces need to be to enable the part to attain the required level of precision. In particular, during inspection on the measuring machine, unnecessary clamping forces should be avoided to prevent any critical deformation of the part.
It is surprising how often one sees expensive measuring machines in the inspection departments, but the clamping tools required to clamp the parts correctly and hold distortion to a minimum are frequently missing. Often, unsuitable vices usually employed in manufacturing are used, or parts are held in place using Plasticine, adhesives or other makeshift solutions. Even self-made clamping equipment is used, despite the fact that the market has long responded to the needs of measuring technicians and now offers highly satisfactory solutions to many clamping tasks.
dk offers an extremely extensive modular system of elaborate clamping elements, comprising well-considered modules with a truly exciting array of options. Whether you need to clamp a piece of sheet metal from a car, hold a shaft in place, secure a circuit board, or apply a tiny force to a plastic part measuring just a few millimetres, the solutions from Reutlingen will win you over thanks to their professional and practice-oriented details.
This comes as no surprise, as these solutions are supported by over 25 years of developmental work, which is guided by user’s suggestions. The clamping systems were designed based on practical experience for practical applications. The modular system consists of almost 1000 parts, which allows even intricate pieces to be measured. Those who previously felt forced to improvise when clamping parts to take measurements now have four compatible product ranges – SPANNFIX, QUADERFIX, SCHIENENFIX and MICROFIX – available to them, which ensure a high level of flexibility when clamping parts onto measuring machines.
Reproducible clamping is therefore an immediate reality. Optical measuring machines are able to conduct automatic measurments part by part, as parts can now be inserted with a level of precision that enables the machine to correct the zero point independently. As with the machine tools, the dk modular system can clamp the parts to be measured away from the measuring machine while the machine is running. All you then have to do is simply insert the complete unit to measure the part, making it ideal for inspecting larger series.
Small-parts clamps are ideally suited to holding pieces of sheet metal which have already been trimmed. dk also offers these clamps in special designs.
To enable the measuring process to take place as smoothly as possible, the dk clamping system has an especially compact design in order to reduce the interference of edges to an absolute minimum. This means that it can be used on both optical and tactile measuring systems. The components used are primarily made of high-strength aluminium with an extremely hard, 50-micrometre-thick anodised coating which is applied with a hard-anodising method.
Aluminium parts are mainly anodised in black to prevent any confusion to the measuring electronics on optical measuring machines. The complete dk product range is characterised by details of this kind. For example, the stop teeth on the toothed rail are deliberately produced in their current design in order to clearly differentiate the rails from the workpiece, lightening the workload of the evaluation electronics on the measuring machine. Spring fingers only apply as much force to the workpiece as is necessary to hold it securely in place without deforming or scratching the surfaces. The supports are available in a flat, rounded or magnetic versions in order to meet the demands of any clamping task.
For parts produced on lathes or milling machines, dk offers clamping solutions that are just as sophisticated. For example, dk offers a small, modified chuck that can clamp on the ID of small tubes or rings. The MICROFIX product range is a particularly interesting option here, as it includes a tiny clamping tool similar to a vice, but which works without a clamping spindle. The clamping force is only applied through an inclined surface.
Clamping forces of varying amounts can be achieved by simply inserting weights into a specially designed pouch. Even extremely fragile, tiny plastic parts can be clamped securely without risking deformation. The micro tailstock belongs to the same series and was conceived to measure rotationally symmetrical parts. Three tiny springs apply the clamping force in this case.
The MICROFIX system has a sophisticated system for clamping extremely fragile parts. In this example, the clamping force can be increased by inserting balls.
The miniature vices are no less interesting, as they are equipped with reamed holes on the upper face into which dowels can be inserted. These dowels can be processed individually and used as a support for thin sheet metal which is clamped onto a casing or an opening, for example. It goes without saying that these vices can be combined with other modular elements. These include swivel units which allow you to orient the vice in any spatial position in order to ease measuring the parts clamped.
When you consider the jaws on offer, you may wonder why these ideas have not yet been seen in the product ranges of other manufacturers of vices for machining, as milling machine operators would surely be delighted to have prism jaws with a three-point contact. In any case, these jaws are an enormous help to inspection technicians when measuring round parts.
The NADELFIX is ideal for when parts with free-form surfaces need to be held absolutely securely. With its ingenious design, this system works with over 100 freely movable pins which adapt individually to the shape of the workpiece and can be clamped in this position. This means that the cast part is positioned securely and can be measured precisely. When the Nadelfix reaches its limits, the tensioning strap provides further assistance wherever possible. This system pulls the part into a pair of V-blocks in order to anchor it there to take a secure measurement.
The small-parts clamps resemble oversized tweezers. These components, which may at first glance appear rather unlikely, have a lot of potential. They make it easy to securely grasp a delicate piece of sheet metal which is trimmed in several places so that it can be measured precisely. dk also offers these clamps in special designs which enable even midget parts with an exotic shape to be clamped securely.
The QUADERFIX clamping system reliably grasps larger parts to perform tactile measurement on measuring machines.
dk offers the right starter set to suit every purpose so that parts can be ideally clamped right from the beginning.
Those using optical measuring machines should definitely take a close look at the SCHIENENFIX product. The rails made of high-strength aluminium form the framework for all additional modules on offer. Spring fingers are attached and dividing heads or the pallet system positioned. Units which are firmly screwed onto the rails, such as the prism support or the tailstock, can be adapted to new workpieces very quickly. Of particular interest is the fact that the tailstock hollow cup centres have a slot through which measurements can be made. This also makes it abundantly clear that the dk system was developed based on practical experience.
For light transmitted measurements of shafts, V-blocks can be supplied onto which the shafts are simply laid.
Measuring parts is particularly flexible when the clamping elements are on pallets. As already mentioned, this enables set-ups to take place while the machine is running. In addition, the measuring space remains clear and tidy as unnecessary equipment is removed every time.
Nevertheless, there are still parts that remain a challenge from a clamping point of view and that cannot be clamped satisfactorily with the aforementioned dk solutions. It is for this reason that dk offers Oktofix. This product enables suitable parts to be clamped by simple means and measured using the transmitted light method.
The world of clamping tools for measuring machines is therefore not exactly small. This makes it even more important to establish a thorough plan from the early stages to ensure that treading uncharted territory does not lead down a stony path. The experts at dk know of the difficulties faced and have therefore put together a variety of starter sets which enable you to work effectively. You can extend these basic modules with add-ons, which relieves the pressure involved from the very beginning.
Source: Welt der Fertigung | 3rd edition 2015