Toggle press

Demonstration model of a toggle press for rapid embossing: The crank mechanism at the bottom acts on the central yellow tension rod, which is guided on two vertical slide rods at the top and is connected there with two blue compression rods. These in turn push the two knees formed from the yellow and white bars outwards, which lifts the green press plate.

The toggle press is a lever press with a toggle lever designed by Diedrich Uhlhorn in Grevenbroich in 1817 for minting coins and medals . One or two levers resembling a human knee give this type of press its name.

Layout and function

Knee lever fruit press: After filling in the fruit mixture (B), the press plate (P) is moved downwards by operating the handwheel (a). Then, by turning the handwheel (b) and the spindle (c), the side toggle levers (d and d ¹ ) are pulled together, which press the pressure plate (P) downwards with great force.

Knee lever presses use the so-called toggle lever effect: the further the knee lever is stretched, the slower but more powerful the movement of the press becomes. At the beginning the ram is brought up to the material to be pressed relatively quickly, but the achievable pressing force is still low. The closer the toggle levers get closer to one another, the slower the movement of the press ram becomes while the pressing force increases, since the translation of the leverage force changes continuously. When turning the lever from 0 ° (bent knee) to 90 ° or π / 2 (stretched knee), the path covered by the press plate increases more and more slowly in proportion to the sine . Thus the force increases proportionally to the negative coscan . Toggle presses can be driven electrically , electromechanically , hydraulically , pneumatically or by hand .

The toggle-lever fruit press (picture on the right) has a so-called helmet (H) and an abutment (W). The pressing plate (P) presses a wooden plate onto the material to be pressed, which is also poured into the wooden tub (B), and receives its pressure through the double toggle lever (d; d ¹ ), which is operated by the handwheel (b) via the left-hand spindle (c ) is driven.

At the beginning of the pressing the entire lever apparatus is moved downwards by the turnstile (a) with nut along the spindle axis (D) provided with a thread in the upper part. The toggle device is only used when a greater pressing force is required. The surrounding plate rim (T) of the abutment (W) serves to catch the liquid.

application

Toggle presses are used in various manufacturing processes.

Examples from the metal and plastics processing industry:

• Injection molding
• Die casting
• Shape
• Deep drawing

Examples from the printing industry and graphic arts :

• Letterpress process
• Gravure printing
• Lithograph

Many jacks also work with toggle levers.

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  Toggle press in the printing industry

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  Toggle press for the bookbinding trade

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  Toggle press as a hand press for stone printing

See also

• Hand press

literature

• Kurt Lange: Forming Technology: Basics . Springer Verlag, 2002, ISBN 3-540-43686-3 , ( limited preview in Google book search).
• Eckart Doege, Bernd-Arno Behrens: Handbook Forming Technology: Fundamentals, Technologies, Machines . Springer Verlag, 2010, ISBN 978-3-642-04248-5 , Chapter 5.3.2.2 Knee lever presses, pp. 751 ff ( limited preview in the Google book search).
• Rühlmann, Moritz: Contribution to the history of the oil mills. In: Polytechnisches Journal . 178, 1865, pp. 258-277. (Inventors: the English Sudds, Barker and Atkins)
• G. Lutz, O. Heller, Felix Kassler: Technology of fats and oils. Handbook of the extraction and processing of fats, oils and waxes of the plant and animal kingdom . Volume 1, page 247 ( limited preview in Google Book search).
• Pressing (in technology) . In: Brockhaus Konversations-Lexikon 1894–1896, Volume 13, p. 376. The inventor was the Russian I. Nevedomsky, who in 1811 in St. Petersburg for minting coins

Web links

• Hand presses (replica of the Gutenberg press, toggle press, Boston platen press)