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In Focus - Archive August 2010
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Confirmed by the precision measuring machine. Stefan Rothenaicher in Erkheim, Germany, shows that it is worthwhile to set on high-quality clamping systems.
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08-01-2010 -
For tool grinding the toolholder plays an essential role because microns will decide the quality of the manufactured tool edges. In view of small batch sizes and various tools, a multi-purpose toolholder is needed. The holder would have to be precise for exact cutting edge geometries and surfaces, slim to avoid interference between the grinding wheel, powerful for very short clamping depths, and have a high material removal rate as well. Flexibility is also required for covering many different shaft diameters. All of these requirements are persuading companies to use automated grinding machines in order to reduce their current costs. A comparison between popular toolholders will demonstrate the differences of the individual systems and will show which solution pays off in the end.
Precision, flexibility and cost-effectiveness, are three factors, which are decisive for production grinding of standard and special tools as well as for re-sharpening shank toolholders. All of them are significantly influenced by the toolholder, especially where automated machining solutions are concerned.
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The tools, which are clamped in the TRIBOS extensions, are automatically gripped from the rack and are exchanged on the machine.
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With its high repeat accuracy, the hydraulic expansion toolholder is ideal for tool-grinding.
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Collet chucks: Favorable in price but not that precise
Most favorable in price are the universal collet chucks, which are automatically actuated. For automatic loading, each tool is inserted in a collet chuck and is placed into the machine rack. Due to their design, the mountings dispose of a relatively imprecise run-out and repeat accuracy, which worsens over the course of time. During the grinding operation it often causes imbalance and makes it impossible to get precise grinding results. Collet chucks are also used for simple sharpening applications. If they are used for demanding applications though, they soon reach their limits due to the lack of precision. Dust particles can also affect the mountings extremely, they can stick and the whole process can be disturbed. Inferior quality, machine breakdowns, and a higher cleaning effort can be the consequence, which are risks that can no longer be tolerated.
Hydraulic expansion toolholders: precise and
effective
Users who want to be on the safe side, use precision mountings for tool sharpening. Although they are more expensive, they offer a permanently high run-out accuracy and are much more user-friendly. Therefore the power-actuated hydraulic expansion toolholders have proven themselves for automated grinding operations, since they have no dirt-prone openings or gaps and are maintenance-friendly. Their high run-out and repeat accuracy directly improve the geometry of the tool’s cutting edges. Users benefit from an even material removal and a high process reliability. The hydraulic system dampens the mountings during grinding against vibrations and thus provides excellent surface qualities. The high grinding results also increase the tool life by about 75%.
In the same way as collet chuck mountings, the tools are manually inserted into the intermediate sleeves of the hydraulic expansion toolholders, placed into racks and then the machine automatically exchanges it on the hydraulic expansion toolholder which is located on the machine spindle. SCHUNK also equips their mountings with a 25° chamfer at the chuck nose, which reduces the interfering contours by 40%.
The high quality of the hydraulic expansion toolholders does increase their price. The price of the mountings and intermediate sleeves also differentiate from the collet chuck mountings and the collet chucks.
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Polygonal clamping technology and hydraulic expansion toolholders are a perfect duo for tool-grinding.
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For deep grinding of a straight slotted solid carbide stepped driller the hydraulic expansion toolholder and the polygonal clamping toolholder show an ideal performance.
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The "slimming agent" for tool sharpening
A combination of precision mountings and precision extensions are also widely-used. Instead of inserting them into collet chucks or hydraulic expansion bushings, the tools are stored in toolholder extensions and are clamped in hydraulic expansion toolholders for sharpening purposes. Thereby the hydraulic expansion toolholder aligns the extension with the tool and dampens occurring vibrations. The extension also assures less interfering contours.
If TENDO hydraulic expansion toolholders and TRIBOS extensions are combined, the achievable run-out accuracy of normal tool lengths amounts to 0.003 to 0.006 mm, measured at the sharp cutting edge. This excellent run-out accuracy helps to achieve very precise tool geometries.
For tool clamping, the polygonal clamping technology uses a polygon-shaped cross section. For tool change, the toolholder is located in a clamping device and then actuated with a predefined force, which deforms the clamping bore within the permanently elastic range, and the tool shank can be then inserted into the circular bore. As soon as the force is released, the clamping bore re-establishes the initial state and the tool is clamped safely. This clamping operation can be repeated thousands of times, without causing symptoms of fatigue, or loss of the high run-out and repeat accuracy. The extensions are dirt-resistant sealing out even smallest dust particles. Due to the sealed design, they are absolutely maintenance-free. For automatic loading of the grinding machine, polygonal extensions are available, even with a gripper collar.
The heat shrinking extensions can be used in a similar way. They are heated in a heat shrinking unit and the bore slightly expands. Then the tool shank can be inserted and the extension is cooled down again. Thereby the mounting shrinks to its original size and clamps the tool safely. However, in case of the heat shrinking mountings two risks can occur, that users burn at the mounting, and in the course of time, the mountings lose its primarily high repeat accuracy. Moreover, the heat shrinking units are more expensive than a hydraulic expansion device for polygonal clamping toolholders.
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Toolholders for automated tool sharpening play an important role.
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During the automatic clamping operation, the tool is precisely centrically clamped in the PRISMO.
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Clean oil avoids the penetration of dust particles into the prism toolholder.
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Universalspannfutter: Die Profiliga zum Werkzeugschärfen
Wer beim automatisierten Werkzeugschärfen möglichst flexibel sein will und zugleich auf eine hohe Präzision angewiesen ist, sollte den Einsatz von Universalspannfuttern in Erwägung ziehen. Ein einziges Futter deckt dabei ohne zusätzliche Spannzangen, Zwischenbüchsen oder Verlängerungen ein breites Spektrum an Schaftdurchmessern ab. Jüngstes Beispiel für ein solches Profi-Schärffutter ist das hochgenauen Prismenspannfutter PRISMO von SCHUNK. Es spannt sämtliche Schaftdurchmesser zwischen 5 und 20 Millimeter hochpräzise und sicher. Bei einer Ausspannlänge von 2,5 x D und einem Werkzeugdurchmesser von 20 mm gewährleistet das Schärffutter eine Spannwiederholgenauigkeit < 0,005 mm. Dabei verhindert es zugleich Taumelschlag. Mit seinem variablen Spanndurchmesser, einer dreifachen Prismenführung sowie ineinander verzahnte Spannbacken bietet die flexibel einsetzbare Aufnahme ideale Voraussetzungen für die automatisierte Fertigung kleiner Losgrößen.
Bei PRISMO wird jede der fünf hartstoffbeschichteten Spannbacken von einem erodierten Doppelprisma geführt. Ein drittes Prisma ist unmittelbar auf die Spannfläche erodiert, die direkt am Werkzeugschaft anliegt. So passt sich das Spannmittel exakt an den jeweiligen Werkzeugdurchmesser an - ein deutlicher Unterschied zu bisher am Markt erhältlichen Lösungen, bei denen die Spannfläche einfach nur rund geschliffen ist. Selbst Einlippenbohrer und Werkzeuge mit Drall können in dem Schärffutter von SCHUNK präzise bearbeitet werden. Aufgrund der diamantähnlichen Hartstoffbeschichtung halten die Spannbacken selbst extremen Beanspruchungen durch Hartmetallwerkzeuge auf Dauer stand.
The constructive set-up, the basic bushing as well as the robust design contribute to an extremely high rigidity of the toolholder. Moreover, the stable guidances ensure that the grinding wheels will not swing up. In order to avoid dirt and to maintain permanently the high precision, the mounting is washed with cleaned oil during the grinding operation. Independent from the tool diameter, the X-axis of the grinding toolholder stays unchanged. Every chuck jaw remains in the same axial position. Time-consuming additional programming and the risk of a crash due to an unconsidered off-set of the X-axis, is no longer to worry. For connecting the prism toolholder to the grinding machine, SCHUNK offers a matching flange for the interfaces of the most important manufacturers of tool-grinding machines, which aligns and adjusts the toolholder quickly and easily.
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Supplying independent from a system
SCHUNK offers an extremely broad spectrum of precise toolholder systems for tool-sharpening. With more than 1,800 employees, a nationwide network of area sales managers in Germany, 23 international subsidiaries, distributing partners in more than 50 countries as well as a world-wide operating service, SCHUNK promises that the user will be advised objectively and independent from any system and will receive the optimum solution for his clamping task.
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2010-12
Clamping large turned parts safely
Launched from the energy technology, machining of large parts on lathes has become more important in the past few years. This causes a lot of pressure which has to be absorbed by the clamping device. This factor makes it all the more surprising that many users still use traditional clamping solutions, which are costly to set-up, clean and maintain. Modern clamping devices do more than assuring safe clamping, they increase precision of the workpiece, reduce set-up times, and minimize maintenance efforts. This also applies for chucks and jaw boxes.
 more...
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2010-10
Grippers with additional benefits
The figures speak for themselves: SCHUNK, the leading expert for clamping technology and gripping systems has sold thousands of sensors for handling applications. While the status of the actuator has been monitored in the past, modern sensors transform the grippers into intelligent helpers, which can measure, inspect, sort and accelerate the whole process simultaneously. The question on their efficiency potential is answered with an overview of the current sensor systems for handling applications.
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2010-09
Gripping Technology for Industrial Robots
Industrial robots work quickly, reliably and never stop. The achieved output and quality significantly depends on the individual periphery, particlularly of the gripping sytems. In the hunt of the optimum gripper, engineers and users have to consider a large variety of influencing factors. In addition to efficiency and process-reliability, sustainability of the gripping systems playes an increasing role.
more...
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2010-08
Efficient toolholders for automated tool grinding
For tool grinding the toolholder plays an essential role because microns will decide the quality of the manufactured tool edges. In view of small batch sizes and various tools, a multi-purpose toolholder is needed. The holder would have to be precise for exact cutting edge geometries and surfaces, slim to avoid interference between the grinding wheel, powerful for very short clamping depths, and have a high material removal rate as well. Flexibility is also required for covering many different shaft diameters. All of these requirements are persuading companies to use automated grinding machines in order to reduce their current costs.
more...
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2010-07
Pick & Place Solutions in Comparison
In order to assemble components fast and precisely, operators can choose between many different Pick & Place solutions. The performance features of the systems vary from each other. To find the best solution, the advantages and disadvantages of each system should be compared.
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2010-06
Energy efficient gripping
In the best of case scenario, energy-efficient automation modules should reduce energy consumption of the handling system and increase cycle times and output. It helps conserve the environment and saves money if you focus both measures.
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2010-05
Factor of Success Engineering -
With virtual simulations to the optimum clamping solution
How does a component deform during the clamping process and machining? Which clamping solution assures that the workpiece has the exact dimensions? How can an existing clamping device be ideally used? Virtual simulations are giving valuable answers to these and simular questions. By means of the Finite Elements Method (FEM) deformations and component payloads can be calculated, which allows a comparison of the individual clamping options and how to optimize them. In turn, process and investment reliability are increased, development times shorten, the selection of the suitable clamping device is easier and costs are lowered.
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2010-04
Magnetic Clamping Technology - efficient at a variety of tasks
Magnetism is one of the most fascinating and influential force of our universe. Engineers and technicians use this same force in order to clamp workpieces, or to reliably lift components. Magnetic clamping technology is well-established in various areas, such as grinding, milling, turning, mobile lifting units in production, and for huge crane constructions. Most engineers now know that magnetic clamping solutions reduce set-up times by about 80 percent, that workpieces are clamped without any deformation, and even coils can be reliably transported.
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2010-03
EU-funded project pushes on the service robots
Experts predict an increase in the pursuit of service robotics. This is no surprise: Modern robot applications offer an enormous potential to the economy and society. Pilot applications already show how robots might become more and more the intelligent helpers of humans. In addition to universities and other research institutes, industrial enterprises should focus on development in this sector, and make it a reality. Therefore the European Union has decided to subsidize the transfer of knowledge between research institutes and industry financially support this pursuit as well.
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2010-02
Flexible packing and palletizing
Adaptive handling systems provide dynamics and profitability if comprehensive ranges and frequent changes in assortment are given.
Every week a new product generation replaces the previous one. These products, which provide new impulses in trade, are a real challenge for the packing process. Faster, process reliable, and flexible automated solutions are in constant demand. They help to keep the handling costs under control, even at an increasing product variety.
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2010-01
How operators "play it safe" during turning operation
If a workpiece loosens from the chuck on a lathe, it can be dangerous to those working in the manufacturing hall. Because of this, the Employer’s Liability Insurance Associations, Standards and Safety Commitees, do everything in their power, to avoid accidents.
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In Focus - 2013
In Focus - Archive 2012
In Focus - Archive 2011
In Focus - Archive 2010
In Focus - Archive 2009
In Focus - Archive 2008
In Focus - Archive 2007
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