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In Focus - Archives Décembre 2011
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During automatic loading of machine tools, the choice of the right clamping vise is important.
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01.12.2011 -
Efficient manufacturing means automated manufacturing. This particularly applies if large series are machined. This is when the clamping vises, which are the direct interface to the workpiece, playing an important role. In only a few seconds, they have to mount the components, safely and precisely align them, clamp them with-out deformation, and after machining they have to be reliably released. In view of the several million clamping cycles, which have to be carried out by many clamping vises being exposed to chips and coolant, process reliability is one of the decisive factors of success.
For clamping force blocks, automated mass production can be tricky. For example, the cycle times for machining pipe ends are a little under two seconds. In view to such a cycle rate, there is no time for compromises and half-hearted solutions. Those who want economic manufacture should seriously consider the following points when selecting a clamping vise:
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Concentrated: The TANDEM clamping force blocks from SCHUNK offer a high clamping force at narrow rooms.
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Clamping force:
Depending on the drive medium, modern clamping force blocks achieve clamping forces of more than 50,000 N. For some types of components and machines these high forces are sometimes not sufficient. Here the operators are well advised to purchase a particularly robust clamping force block because excessive hydraulic or pneumatic pressures aren’t a problem, and they can even achieve high clamping forces.
Stability/repeat accuracy:
The rigidity of a clamping force block plays an important role on the achievable precision at the workpiece. Due to their high rigidity, clamping vises with a one-pieced base body are perfect. If they are combined with precision kinematics, and long, ground jaw guidances, a repeat accuracy of up to 0.01 mm can be achieved. Ideally, special fitting screws ensure that the vises can be exchanged at a high repeat accuracy.
Stroke:
If components are clamped across interfering contours or around the entire circumference, long jaw strokes will pay off. When choosing the right clamping block, it has to be made sure that a long jaw stroke will not impair the clamping force.
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Pipe machining - Clamping force blocks should properly work even after several million cycles, as it is shown here during ma-chining of pipe ends.
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TANDEM rotating fixtures -
The more compact the clamping force block is, the more varied the range of possibilities in the machine.
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Interfering contour/design:
The more compact a system is, the more important compact clamping vises become. Ideally, the outside contours of the clamping blocks are optimized, leaving more space in the machine. Here again, it is important that the available space will not impair the clamping force. Even compact clamping vises should dispose of high clamping forces. Also in terms of process reliability the design plays an important role. The smaller the gap, less dust and chips that can penetrate into the clamping module, which reduces the error rate of the whole system.
Weight:
If clamping modules are moved in a rotary indexing machine at every cycle, their weight plays an important role. Heavy modules negatively influence the cycle rates and the energy efficiency of the system. Possible weight reductions shouldn’t impair the clamping force.
Flexibility:
Depending on the order, it can be important that the same clamping module can be used for I.D. and O.D. clamping. Not every clamping vise provides identical clamping forces for both types of clamping. There are often enormous differences, which highly reduce flexibility. Moreover, flexibility can increase, if the modules can be assembled in any possible position.
Maintenance:
For ensuring a consistently high clamping force of the clamping modules, the guiding surfaces have to be regularly lubricated. If the modules are closely positioned next to each other, maintenance work can be unnecessarily time-consuming. Because of this, some operators forego the maintenance works for the sake of convenience, but this will endanger the complete manufacturing process over the course of time. Modern solutions provide for several lubrication nipples, which can be used on option. Even in case of narrow machining areas, maintenance work can be easily and quickly done.
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TANDEM cross section
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NSA plus modules allow process reliable pallet change, and leave plenty of room in the machine.
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Scope of program:
In the past, different types of clamping modules were required, and many companies have an outright collection of various clamping modules. They have no influence on the operation, but in case of a crash this can cause a huge problem because spare parts of every module are rarely kept in stock. Modular systems are offering decisive advantages, where various variants are standardized. This particularly applies for drive variants. Ideally, the operators can choose between pneumatic, hydraulic, spring, or manually actuated modules according to their requirements. Pneumatic modules have the advantage that compressed air is available from many systems, and hydraulic power units are not required. In case of a leakage, no oil will run out. With hydraulic modules, the clamping force can be defined during machining if required, and can be comfortably monitored via the hydraulic pressure.
One of the pioneers for clamping systems for automated mass production is SCHUNK, the competence leader for clamping technology and gripping systems. With its TANDEM series, the innovative family-owned company is setting standards in the field of clamping force blocks. Concentrated clamping forces of up to 55 kN, and a repeat accuracy of up to 0.01 mm ensure exact and economic results. The powerhouses are also designed for challenging milling machining with a high metal removal rate, high number of cycles, and minimum tolerances. Due to the two inte-grated jaw interfaces, top jaws with tongue and groove as well as jaws with fine serration can be used. On option, the clamping force blocks are available with a standard stroke, long stroke, or as a console clamping block with fixed jaw in sizes between 64 to 250 mm. They can be actuated pneumatically, hydraulically, by spring, or manually. The unique SCHUNK modular system comprises 30 different standard clamping force blocks, and thus creates optimum conditions for economic mass production.
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Reliable pallet change
With the compact quick-change pallet module VERO-S NSA plus, SCHUNK also offers a suitable solution for the automated pallet change. The module is flat, which allows for enough space for workpiece and axis movement in the machine room. If required, it can be directly integrated in the machine table. During pallet change a forced air flow cleans the short taper from chips and dirt, and ensures chip-free surface contact of the workpiece. Then a low-wear centering ring takes over the reference-precise centering of the pallet. If the turbo function is actuated, the pull-down force of the VERO-S NSA plus amounts to 30,000 N, and the holding force
achieves 100,000 N. The module is locked via two clamping slides, and provides for a form-fit, self-locking fixation of the centering ring. Thereby the repeat accuracy amounts to less than 0.005 mm. By means of an air control system it can be monitored whether the pallet is precisely clamped. Process failures and errors in machining can be prevented right from the start. For removal, a pin lifts the pallet and thus facilitates the automatic change with a robot. The slim VERO-S NSR ro-bot coupling from SCHUNK thereby ensures a reliable handling and a safe hold.
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12.2011
Clamping solutions for automated mass production
Efficient manufacturing means automated manufacturing. This particularly applies if large series are machined. This is when the clamping vises, which are the direct interface to the workpiece, playing an important role. In only a few seconds, they have to mount the components, safely and precisely align them, clamp them with-out deformation, and after machining they have to be reliably released. In view of the several million clamping cycles, which have to be carried out by many clamping vises being exposed to chips and coolant, process reliability is one of the decisive factors of success.
 Pour en savoir plus…
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11.2011
Modularity the factor of success
When designing gripping systems for handling and assembly applications, standardized modular systems will play an increasingly important role in the future. They reduce the necessary time for project planning and commissioning, and lower the investment costs. Due to the standardization, they offer optimum preconditions for stable processes. Since modular designed units can be flexibly modified and enlarged, they can be re-configurated for any changes that come up in the future.
Pour en savoir plus…
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10.2011
Producing more efficient
For a number of years, everybody was talking about the energy efficiency issue. Increasing energy costs, a growing environmental awareness, and the political guidance were all triggers for many companies to highlight the energy consumption of machines and components in their communication with the public. Efficiency is much more than simple energy efficiency now, especially when considering the
time- and cost aspects in regards to efficiency. When all these factors have been considered in a holistic way, the full potentials for modern machining and production become visible. The modern clamping devices and gripping systems make it clear how complex the possibilities are.
Pour en savoir plus…
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09.2011
Welding demanding materials crack- and pore-free
Laser welding technology is second-to-none, regardless of whether you are dealing with gears and injection molds or delicate and challenging welding works. When conventional cw lasers and many Nd:YAG-lasers reach their limits, modern process strategies can help to machine demanding welding metallurgies, different types of materials, or micro components process reliably and efficiently. Laser welding is particularly used if components have to be joined at a high welding speed, because slim welding seams, and a low thermal distortion are required. Compared with other welding techniques, the energy during laser welding fully penetrates into the material.
Pour en savoir plus…
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08.2011
More than a "Stopgap":
Intermediate sleeves ensure safe clamping and precision
They appear to be unimposing - but they are located at a decisive interface in the chain of the metal cutting process. Between toolholder and workpiece, the intermediate sleeves influence reliability and precision of the clamping operation. The thin-walled, mostly slotted precision sleeves cover the difference between the clamping diameter of the toolholder, and the workpiece which has to be clamped. Functioning like reduction inserts, they multiply the fields of application of the toolholders or arbors, compensate tolerances, and ensure safe and gentle clamping of gear wheels. The newest sleeve design can do even more. Intermediate sleeves with nozzle effect extend the tool service life and increase the volume machining.
Pour en savoir plus…
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07.2011
Changing, machining, compensating -
current trends in robot accessories
In dealing with industrial robot efficiency cycle rate and process reliabilty largely depend on their front ends, the grippers and other tools, but also from the effectors’ interfaces to the robot arm. Robot accessories have a great influence on the robot’s performance, flexibility and fields of application. Latest developments of quick-change systems, driven tools, compensation units, and power sensors show that the potentials of modern accessory components are enormous. Experts assume that their importance for handling, assembly and manufacturing will continuously increase.
Pour en savoir plus…
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06.2011
Deformation-free clamping:
From the plastic chuck jaw to the hybrid chuck
In case of rings, housings and other workpieces which are highly deformable dur-ing processing, conventional 3-jaw chucks quickly reach their limits. If the clamping forces are too low, there is no secure hold. If they are increased, workpieces de-form, and precision is reduced. A comparison shows the alternatives, the differ-ence between them, and how users can achieve an optimum result.
Pour en savoir plus…
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05.2011
Service robotics is the future key market
Insiders are convinced that golden times lie ahead for service robotics. Around the world companies and institutes have recognized the potential of robots as helpers for humans, and are working on everyday solutions. All different kinds of businesses are interested in service robotics, from large companies, to innovative startups, and also conventional manufacturers of industrial robots, electronic and automation components.
Pour en savoir plus…
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04.2011
Having set-up times under control
You cannot earn money with a turned off machine. However, in many companies the workpieces are still set-up in a complicated and time-consuming way on a grooved table while the plant is turned off. But solutions exist, which optimize the machine tool load. Modern quick-change pallet systems demonstrably accelerate the machining process, and at the same time, ramp up the precision and process reliability score. This leads to a reduction of set-up costs of up to 90%.
Pour en savoir plus…
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03.2011
Toolholders for micro cutting
Clamping tools used for micro cutting have their own rules. The subtle tools, the high spindle speeds, and the extreme precision requirements are a challenge for every tool manufacturer and user. Those who want to achieve continuously precise results, need mountings with a high run-out accuracy and balancing grade. Moreover, they should be as slim as possible and resistant to dirt. Furthermore, they have to assure that even small tools can be precisely adjusted and exchanged.
Pour en savoir plus…
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02.2011
Leight-weight design increases efficiency of Gripping Systems
Light-weight modules are now playing an increasing role in the area of gripping systems. Integrated into the system, they are saving energy at the same efficiency, or achieve a considerably higher efficiency at the indentical energy consumption. In both cases, the efficiency of the whole system is increasing. This is why the lightweights are so interesting for plant manufacturers, system integrators, and users. Since light-weight solutions had the reputation of being overly expensive in the past, recent developments now show that efficiency and cost control can go hand-in-hand. Modern designs, materials and techniques are paving the way to lighter solutions, which are rigid and robust, too. This also offer many more advantages.
Pour en savoir plus…
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In Focus - 2013
In Focus - Archives 2012
In Focus - Archives 2011
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