EP1893401B1 - Device for stamping and/or shaping sheet metal, wires and similar - Google Patents

Abstract

The invention relates to a device (10) for stamping and/or shaping sheet metal, wires or similar. Said device comprises a table (15) which is used to receive an interchangeable column structure (16) which comprises a lower part (17) and an upper part (19) which are guided in a displaceable manner in relation to each other and in a vertical manner, by means of several vertical guiding columns (18), in addition to a lower drive (20,.., 30) which is arranged below the table (15) and which is used in order to produce traction forces which are oriented in a downward direction, which are coupled to the upper part (19) of the column structure (16) by means of a plurality of traction rods (31, 32). The aim of the invention is to produce a more compact device with a simplified construction and at the same time increasing the quality of the processing steps such that the traction forces are coupled directly to the upper part (19) of the column structure (16).

Description

The present invention relates to the field of stamping and forming technology. It relates to a device for punching and / or forming of sheets, wires and the like. According to the preamble of claim 1.

STATE OF THE ART

For performing punching and / or forming of sheet metal, metal strips, wires or the like. Universal presses are often used, which have a table on which a guided in the vertical direction, motor or hydraulic driven ram can be lowered cyclically. Between the table and the plunger usually commercial, falling under the so-called Normalien column racks are used, each having an upper and lower part for receiving the actual tools. The upper and lower parts of the column frame are guided in vertical movement relative to each other by a plurality (e.g., 2, 3 or 4) of guide columns. The upper part of the pillar frame is firmly connected to the plunger of the press, the lower part fixed accordingly on the table.

For the drive of the ram, there are different configurations. One of these configurations includes an eccentric or crank drive located above the ram and usually equipped with a large flywheel gives the heavy ram a steady movement. Because in this configuration, large and moving masses are present above the column frame, the press must be made very stable beyond the table, so that the forces occurring during the punching process can be safely collected. At the same time, however, it must be taken into account that there is adequate access to the table in order to be able to feed the material to be processed into the work area and, if necessary, to be able to change tools or pillar racks. One possibility for this is provided by the so-called C-presses, whose frame has the shape of a C open on three sides. However, the one-sided design of the C-presses can lead to deformation when high pressing forces are exerted. Another possibility is a columnar structure in which the superstructure of the machine is carried by columns arranged at the corners of the generally rectangular table. If a flywheel is present, special measures must be taken to be able to stop the press in an emergency in the shortest possible time. These are - combined with brakes - usually used quick release clutch mechanisms, which are arranged between flywheel and ram, and are triggered in an emergency.

Another problem is the introduction of the pressing force in the plunger. If the force is introduced centrally, can - especially if the tools are not centrally located to the plunger - transverse forces arise, which adversely affect the work result. Therefore, proposals have already been made, by means of toggle units, to introduce the forces generated centrally by an eccentric drive into the same place at different points of the ram (see, for example, US Pat EP-B1-0 765 735 ).

Furthermore, proposals have long been known to arrange the drive of the plunger in such presses to save space below the table ("sub drive") and to transmit the forces generated there via tie rods on the above the table mounted plunger. Such presses are for example in the US-A-3,082,725 or the US-A-2,727,573 or the GB 786.695 or the WO-A1-99 / 02333 described.

When in the WO-A1-99 / 02333 In the disclosed press, the forces transmitted to the ram via the tie-rods are generated by a common frame movably disposed below the table, to which the tie-rods guided through the table are fastened. At the presses from the US-A-3,082,725 or the US-A-2,727,573 or the GB 786.695 The tie rods are added in the manner of a connecting rod individually via crank or eccentric drives in an up and down movement, which is transmitted to the plunger. In the case of a rectangular plunger, four tie rods expediently engage at the corners of the plunger. The tie rods are combined in pairs. The tie rods of both pairs rotate in opposite directions, so that lateral forces on the plunger are compensated.

The generic US-A-5,566,373 discloses a press for powder metallurgy having on a table a press frame having a top over which a crossbar is disposed which are movable downwardly with two columns formed as tie rods to produce the pressing pressure on a metallurgical powder. The coupling of the tensile forces takes place directly on the transom.

The DE-A-3541387 discloses a press for making molded articles from powdered materials. Similar to the mentioned US-A-5,566,373 engages the force of tie rods primarily on a crossbar, which is connected via a press cylinder with an upper part of a column frame.

The JP-A-06170591 discloses a press with two tie rods. This is not suitable for punching. The SU-A-424735 discloses a press which also has two tie rods acting on a crossbar. The EP-A-1149688 discloses a drive for a press, a column rack is not provided.

The US-A-3,195,449 discloses a punch press having a movable head over a table which is guided on four pillars. The head is moved with an eccentric drive, which acts on two opposite narrow sides of the head.

• Der schwere Stössel stellt eine grosse bewegte Masse dar, die bei der zyklischen Bewegung erhebliche Erschütterungen verursacht, einen unruhigen Lauf der Maschine zur Folge hat und zu entsprechenden Schallemissionen führt.
• Der Stössel muss oberhalb des Tisches vertikal geführt werden, was nicht nur einen erheblichen konstruktiven Aufwand bedeutet, sondern auch Platz beansprucht und den Zugang zum Arbeitsraum der Presse erschwert.
• Wird innerhalb des Antriebs ein Schwungrad eingesetzt, müssen besondere Vorkehrungen für den schnellen Stillstand der Presse beim Not-Aus getroffen werden.
• Durch den Stössel ergibt sich eine vergleichsweise grosse Bauhöhe der Maschine, die bei Temperaturschwankungen zu deutlichen Veränderungen der Werkzeugendlage im unteren Totpunkt führen kann.
• Die Kräfte auf die Werkzeuge werden relativ weit oberhalb der Werkzeuge in den Stössel eingeleitet, was die Entstehung von störenden Querkräften begünstigt.

However, the known, working with a ram presses have several disadvantages:

• The heavy ram is a large moving mass that causes significant vibration during cyclic movement, resulting in a restless running of the machine and leads to corresponding noise emissions.
• The ram must be guided vertically above the table, which not only means a considerable design effort, but also claimed space and difficult access to the working space of the press.
• If a flywheel is used within the drive, special precautions must be taken for the rapid shutdown of the press during emergency stop.
• By the ram results in a comparatively large height of the machine, which can lead to significant changes in the tool end position at bottom dead center with temperature fluctuations.
• The forces on the tools are introduced relatively far above the tools in the plunger, which favors the formation of disturbing transverse forces.

PRESENTATION OF THE INVENTION

It is an object of the invention to provide a device for punching and / or forming of sheets, wires and the like., Which avoids the disadvantages of the known devices and in particular by a space-saving, highly simplified design, low vibration and noise emissions during operation, a simplified drive and in particular a high quality of the punching or forming process is characterized.

The object is solved by the entirety of the features of claim 1. An essential feature of the invention is that the device has a Sub-drive has, and that the coupling of the tensile forces via tie rods and without ram directly on the top of a column frame, in which the tools are housed. The device thus requires no longitudinal guides for the hub, since this task is taken over by the guide columns of the commercial pillar frame. All materials between column frame and actuator are only loaded under pressure; that is, even at high punching forces, the machine frame can be manufactured with minimum material costs. Due to the low overall height of the machine, temperature fluctuations have a very small influence on the tool end position at bottom dead center.

The sub-drive is preferably designed so that the tensile force is generated individually for each of the tie rods, and that the tensile force of each tie rod is generated by an associated eccentric or crank drive.

Particularly favorable is the distribution of tensile forces, since according to the invention at least two pairs of tie rods are provided, which couple the tensile forces on opposite sides of the upper part. This in particular if according to an embodiment of the invention, the tie rods of a pull rod pair of eccentrics or cranks are driven, sitting on a common shaft, and in particular when two similar pairs of tie rods are provided, and the two tie rod pairs arranged and driven are that their movement is mirror-symmetrical to a vertical median plane, and provided within the column frame work space for receiving the Tools between the two tie rod pairs lies. The four tie rods distribute the force on the tool. Even with off-center power requirements, the tool closes absolutely parallel. Due to the opposing tie rods, the lateral forces are released on the guide system of the column frame. The direct introduction of force from the four tie rods on the tool eliminates the large mass of the ram. This achieves a very quiet running of the machine. As the four tie rods work in opposite directions, the moving masses of the tie rods are released in the horizontal axis.

Particularly simple is the sub-drive when the two pairs of drawbars are each driven by a common shaft when the two shafts are arranged parallel to each other when the two shafts by two meshing gears, each of which is rotatably mounted on one of the shafts , rotate in opposite directions and are synchronized with each other when one of the two shafts, in particular via a gear transmission, is driven by a drive motor, and when the drive motor is an electrically operated servomotor. The direct drive of the eccentric shafts eliminates the Flywheel. Further eliminates the clutch and brake, which require maintenance by the wear. By eliminating the flywheel can be at a very low speed (1 min ^-1 ), based on the eccentric shaft, worked. If the machine is driven by a servomotor and secured by sensor technology, it can be stopped within a few degrees of the eccentric in the fault or emergency stop area. The minimal use of momentum forces thus allows optimum protection for people and tools.

Preferably, the tie rods of a tie rod pair are connected to each other at the upper end by a horizontally extending pressure bar, which pressure bar is rotatably mounted with its ends respectively in one of the tie rods, wherein the pressure bar for coupling the tensile forces is screwed to the upper part of the column frame.

Due to the opposing drive of double eccentric shafts, mass balance in the horizontal plane is provided without further measures. The mass in the vertical plane, which results from the stroke is limited by the inventive concept to the minimum necessary. However, it can additionally be provided in the sub drive means for mass balance of up and down moving upper part of the column frame, which in particular include counterweights, which are mounted rotationally and unbalanced on the shafts.

The sub-drive is preferably housed in a sub-frame, and the table is arranged on top of the sub-frame. The sub-drive comprises a drive motor and a plurality of parallel shafts, wherein the sub-frame has two opposite side walls, and the drive motor and the shafts are mounted in the side walls.

A further embodiment of the invention is characterized in that the column frame is substantially rectangular, that within the column frame four guide columns are provided, which are placed in the area of the four corners of the column frame, and that the tensile forces are coupled respectively in the immediate vicinity of the guide columns in the upper part of the column frame.

The column frame can be driven in a particularly effective and reliable manner if the tensile forces are coupled into the upper part of the column frame close to the point where the forces for stamping or forming within the column frame are required.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

in einer vereinfachten Seitenansicht ein Ausführungsbeispiel einer Vorrichtung nach der Erfindung, wobei Teile des Unterantriebs der besseren Sichtbarkeit wegen durchgezogen gezeichnet sind, obgleich sie eigentlich verdeckt sind; und

Fig. 2

die Vorrichtung aus Fig. 2 in einer anderen Ansicht mit dem Blick ins Innere des Untergestells.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it

Fig. 1

in a simplified side view of an embodiment of a device according to the invention, wherein parts of the sub-drive drawn for better visibility because of drawn, although they are actually hidden; and

Fig. 2

the device off Fig. 2 in another view, looking into the interior of the undercarriage.

WAYS FOR CARRYING OUT THE INVENTION

In the Fig. 1 and Figure 2 shows various side views of a pressing device according to a preferred embodiment of the invention. The device 10 comprises a table 15 arranged on the upper side of a lower frame 11, on which a commercial pillar frame 16 is mounted. The base 11 consists essentially of a rectangular Base plate 12 and two parallel, opposite side walls 13 and 14 ( Fig. 2 ), which are mounted vertically standing on the base plate 12. The table 15 rests on the side walls 13, 14 on top and is supported by them. It goes without saying that, instead of a subframe screwed together or welded together from individual plates, it is also possible to use a subframe which is made in one piece, for example as a cast part. Under the base plate 12 can be provided at the corners height adjustable feet 41, 42, 42 'to compensate for unevenness of the floor when setting up the device.

Within the undercarriage 11, a lower drive is arranged, which comprises a drive motor 20 and a plurality of shafts 23, 27 and 28 having gear. About provided at the ends of the shafts 27 and 28 eccentric drives 29, 30 are four tie rods 31, 32, 32 'driven individually, the downward pulling forces (simple arrows in Fig. 2 ) directly into the column frame 16. The shafts 23, 27 and 28 are rotatably mounted in the side walls 13, 14 of the undercarriage 11 by means of suitable bearings 39, 40. Similarly, the drive motor 20 is mounted in the side walls 13, 14 and protrudes with its motor shaft 46 from the side wall 14 to the outside. On the motor shaft 46 is seated a first gear, which drives a toothed belt 21, a seated on the shaft 23 second gear 22. On the shaft 23, a third gear 26 is rotatably disposed in the interior of the undercarriage 11, which meshes with a fourth gear 25 on the shaft 27. In turn, the fourth gearwheel 25 meshes with an equally large fifth gearwheel 26 on the shaft 28, so that the shafts 27 and 28 rotate at the same speed but opposite. The gears 24, 25 and 26 are in the view of Fig. 1 hidden by the side wall 14, but are drawn for better visibility because of solid (in Fig. 2 the shaft 23 with the gears 22 and 24 is completely omitted, to release the view of the shaft 27).

At the outwardly projecting ends of the shafts 27 and 28 respectively eccentric 29, 30 are mounted on which the tie rods 31, 32, 32 'with their lower ends are rotatably supported by the bearings 37, 38, and cause a cyclical up and down movement of the tie rods 31, 32, 32 ', when the shafts 27, 28 - driven by the drive motor 20 - rotate. The length of the tie rods 31, 32, 32 'is such that they end shortly above the column frame 16. The pillar frame 16 comprises a lower part 17 and a top 19. With the flat underside of the lower part 17, the pillar frame 16 rests on the table 15 and is releasably secured on the table 15 by means of clamping claws or the like. Lower part 17 and upper part 19 are connected to each other by a plurality of columns 18. The columns 18 guide the upper part 19 precisely in the vertical direction when it is displaced relative to the lower part 17. In the present embodiment, upper part 19 and lower part 17 are rectangular and four columns 18 are provided, which are placed at the corners of the column frame 16. The pillar frame may also have another basic shape. Likewise, only two or three, or even more than four columns may be present to guide the upper and lower parts 19 and 17 of the pillar frame 16 relative to one another during the punching or forming process. Between the columns 18 of the pillar frame 16 is the actual working space 44, in which the attached to the upper and lower part 19, 17 tools are housed.

The inventive direct initiation of the tensile forces generated in the individual eccentric drives 29, 30 and transmitted by the tie rods 31, 32, 32 'into the column frame 16 takes place on top of the upper part 19. For this purpose, preferably two extending transversely over the upper part 19, on the upper side resting pressure bar 33, 34 are provided, which are screwed at several points with the upper part 19. The pressure bars 33, 34 protrude laterally beyond the upper part 19 at both ends with circular-cylindrical sections. At the circular cylindrical sections, the tie rods 31, 32, 32 'by means of bearings 35, 36 rotatably articulated. When the two shafts 27, 28 are driven by the drive motor 20 and rotate in opposite directions, the rotational movement is converted via the eccentric drives and tie rods 31, 32, 32 'in a cyclical up and down movement of the upper part 19 of the column frame 16 (double arrow in Fig. 2 ). The punching or forming process takes place in the downward movement of the upper part 19, wherein the forces required for this purpose are transmitted as tensile forces from the lower drive via the tie rods 31, 32, 32 '. When arranged in the working space 44 tools that required for punching or forming forces can occur at different points of the tool. In general, it is particularly favorable for the operation of the drive when the tensile forces are coupled in each case close to the point in the upper part 19 of the column frame 16, where the forces for punching or forming within the column frame 16 are required.

Since the tie rods 31, 32, 32 'move in pairs in a common mode and the pairs of rods 27, 28 driven Zugstangenpaare mirror images move to a vertical center plane 44 through the working space, compensate any lateral forces largely. Since only the comparatively small mass of the upper part 19 and of the upper tool is moved during the punching or forming process, comparatively low vibrations and a comparatively low noise development result. Furthermore, no large flywheel masses are necessary for the operation. This has the advantage that when using a servo motor as a drive motor in the case of emergency stop the device can be stopped with appropriate control directly by stopping the engine in a very short time. Instead of a servo motor but also a simple electric motor with additional braking device (brake motor) can be used as a drive motor. In order to compensate for the movement of the upper part 19 in terms of mass, counterweights 43 can be attached to the shafts 27, 28 in a torque-proof and unbalanced manner.

• Die für den Stanzvorgang benötigten Kräfte werden möglichst nahe bei den Werkzeugen aufgebracht.
• Die Presse benötigt keine Längsführungen für den Hub, da diese Aufgabe durch die Führungssäulen des handelsüblichen Säulengestelles übernommen wird.
• Durch die zwei Doppelexzenter, welche die 4 Zugstangen antreiben, ist die Parallelität der Kräfte, die auf das Säulengestell bzw. auf das Werkzeug wirken, jederzeit gewährleistet. Vier Zugstangen verteilen die Kraft auf das Werkzeug. Auch bei aussermittigem Kraftbedarf schliesst das Werkzeug absolut parallel.
• Alle Materialen zwischen Säulengestell und Antrieb werden nur auf Druck belastet; d.h. auch bei hohen Stanzkräften kann das Maschinengestell mit minimalstem Materialaufwand hergestellt werden.
• Durch die geringe Bauhöhe der Maschine haben Temperaturschwankungen einen sehr geringen Einfluss auf die Werkzeugendlage am unteren Totpunkt.
• Durch den gegenläufigen Antrieb dar Doppelexzenterwellen ist ein Massenausgleich in horizontaler Ebene ohne weitere Massnahmen gegeben. Durch die gegenläufigen Zugstangen werden die Querkräfte auf das Führungssystem des Säulengestelles aufgehoben.
• Die Masse in der vertikalen Ebene, die durch den Hub entsteht, wird durch dieses Konzept auf das minimal Nötigste beschränkt.
• Beide vorgenannten Bedingungen gewähren einen möglichst vibrationsfreien Lauf auch ohne komplexen Massenausgleich. Dies auch bei hohen Arbeitsleistungen.
• Durch die sehr kompakte Bauweise werden die Schallemissionen, die im wesentlichen noch durch den Stanzvorgang verursacht werden, von möglichst wenigen metallischen Teilen übernommen.
• Durch diese Antriebsart kann die Maschine sehr kompakt gebaut werden. Die kompakte Bauweise gestattet es, die Maschinen in einem schall- und vibrationsdämmenden Gehäuse unterzubringen, womit die Belastungen für Mensch und Umwelt auf ein absolutes Minimum reduziert werden.
• Wird die Maschine mittels Servomotor angetrieben und durch Sensortechnik abgesichert, kann sie im Störungs- oder Not-Aus-Bereich innert wenigen Graden der Exzenter gestoppt werden. Der minimale Einsatz von Schwungkräften gestattet damit einen optimalen Schutz für Mensch und Werkzeuge.
• Direktantrieb der Exzenterwellen, dadurch entfällt die Schwungmasse. Weiter entfallen Kupplung und Bremse, welche durch den Verschleiss Wartungsarbeit benötigen.
• Durch Wegfall der Schwungmasse kann auch mit sehr kleiner Drehzahl (1 min^-1) bezogen auf die Exzenterwelle gearbeitet werden.
• Durch die direkte Krafteinleitung der vier Zugstangen auf das Werkzeug entfällt die grosse Masse des Stössels. Dadurch wird ein sehr ruhiger Lauf der Maschine erreicht.
• Die vier Zugstangen arbeiten gegenläufig, dadurch werden die bewegten Massen der Zugstangen in der horizontalen Achse aufgehoben.
• Durch den Wegfall der grossen Masse beim Stössel kann die Maschine in sehr kurzer Zeit gestoppt werden.

Overall, the invention provides a device for punching and / or forming, which is characterized by the following advantages:

• The forces required for the punching process are applied as close as possible to the tools.
• The press does not require longitudinal guides for the stroke, as this task is taken over by the guide columns of the commercial pillar frame.
• Due to the two double eccentric, which drive the 4 tie rods, the parallelism of the forces acting on the column frame or on the tool, at any time guaranteed. Four tie rods distribute the force on the tool. Even with off-center power requirements, the tool closes absolutely parallel.
• All materials between column frame and actuator are only loaded under pressure; that is, even at high punching forces, the machine frame can be manufactured with minimum material costs.
• Due to the low overall height of the machine, temperature fluctuations have a very small influence on the tool end position at bottom dead center.
• Due to the opposing drive of double eccentric shafts, mass balance in the horizontal plane is provided without further measures. Due to the opposing tie rods, the lateral forces are released on the guide system of the column frame.
• The mass in the vertical plane created by the stroke is limited by this concept to the minimum necessary.
• Both of the above conditions ensure vibration-free running even without complex mass balance. This also at high work rates.
• Due to the very compact design, the noise emissions, which are still caused by the punching process, are taken over by as few metal parts as possible.
• Due to this type of drive, the machine can be built very compact. The compact design allows the machines to be housed in a sound- and vibration-isolating housing, thus reducing the strain on people and the environment to an absolute minimum.
• If the machine is driven by a servomotor and secured by sensor technology, it can operate in the fault or emergency stop area be stopped within a few degrees of the eccentric. The minimal use of momentum forces thus allows optimum protection for people and tools.
• Direct drive of the eccentric shafts, this eliminates the flywheel. Further eliminates the clutch and brake, which require maintenance by the wear.
• By eliminating the flywheel can be worked with a very small speed (1 min ^-1 ) relative to the eccentric shaft.
• The direct introduction of force from the four tie rods on the tool eliminates the large mass of the ram. This achieves a very quiet running of the machine.
• The four drawbars work in opposite directions, thereby lifting the moving masses of the drawbars in the horizontal axis.
• By eliminating the large mass at the plunger, the machine can be stopped in a very short time.

LIST OF REFERENCE NUMBERS

10

Punching and / or forming device

11

undercarriage

12

baseplate

13.14

Side wall

15

table

16

column frame

17

lower part

18

guide column

19

top

20

Drive motor (servomotor)

21

toothed belt

22.24 to 26

gear

23,27,28

wave

29.30

eccentric

31,32,32 '

pull bar

33.34

pressure beam

35-40

camp

41,42,42 '

Foot (adjustable)

43

counterweight

44

working space

45

midplane

46

motor shaft

Claims (14)

1. Apparatus (10) for stamping and/or forming metal sheets, wires and the like, having a table (15) for receiving an exchangeable column frame (16) which has a bottom part (17) and a top part (19) which are guided in a displaceable manner in relation to one another in the vertical direction by means of a plurality of vertical guide columns (18), and also having a bottom drive (20, ..., 30), arranged underneath the table (15), for generating downwardly directed tensile forces which are introduced into the top part (19) of the column frame (16) by means of a plurality of pull rods (31, 32, 32'), characterized in that the tensile forces are introduced directly at the top part (19) of the column frame (16) and in that there are provided two pairs of pull rods (32, 32') which introduce the tensile forces at opposite sides of the top part (19), in that the pull rods (32, 32') of a pair of pull rods are connected together at the top end in each case by a horizontally extending pressure bar (33, 34) which is mounted in a rotatable manner by way of its ends in each case in one of the pull rods (32, 32'), and in that the pressure bar (33, 34) is screwed to the top part (19) of the column frame (16) in order to introduce the tensile forces.
2. Apparatus according to Claim 1, characterized in that the bottom drive (20, .., 30) is designed such that the tensile force for each of the pull rods (31, 32, 32') is generated separately.
3. Apparatus according to Claim 2, characterized in that the tensile force of each pull rod (31, 32, 32') is generated by an associated eccentric or crank drive (27, 28, 29, 30).
4. Apparatus according to Claim 1, characterized in that the pull rods (32, 32') of a pair of pull rods are driven by eccentrics (29, 30) or cranks which are seated on a common shaft (27, 28).
5. Apparatus according to Claim 1 or 4, characterized in that two identical pairs of pull rods (31, 32, 32'). are provided, and in that the two pairs of pull rods (31, 32, 32') are arranged and driven such that their movement runs in a mirror-symmetrical manner to a vertical centre plane (45), and in that a working chamber (44), which is provided inside the column frame (16), for holding the tools is located between the two pairs of pull rods (31, 32, 32').
6. Apparatus according to Claim 5, characterized in that the two pairs of pull rods (31, 32, 32') are each driven by a common shaft (27, 28), in that the two shafts (27, 28) are arranged parallel to one another, and in that, by way of two gearwheels (25, 26), which are in engagement with one another and are each mounted in a rotationally fixed manner on one of the shafts (27, 28), the two shafts (27, 28) rotate in opposite directions and are synchronized with one another
7. Apparatus according to Claim 6, characterized in that one of the two shafts (27, 28) is driven by a drive motor (20), in particular via a gear mechanism (21, 22, 24, 25).
8. Apparatus according to Claim 7, characterized in that the derive motor (20) is an electrically operated servo motor or brake motor.
9. Apparatus according to either of Claims 5 and 6, characterized in that means (43) for mass balancing the upwardly and downwardly moving top part (19) of the column frame (16) are provided in the bottom drive (20, ..., 30).
10. Apparatus according to Claim 9, characterized in that the mass balancing means comprise counterweights (43) which are fitted on the shafts (27, 28) in a rotationally fixed and unbalanced manner.
11. Apparatus according to one of Claims 1 to 10, characterized in that the bottom drive (20, ..., 30) is accommodated in a subframe (11), and in that the table (15) is arranged on the top side of the subframe (11).
12. Apparatus according to Claim 11, characterized in that the bottom drive (20, ..., 30) comprises a drive motor (20) and a plurality of parallel shafts (23, 27, 28), in that the subframe (11) has two opposite side walls (13, 14), and in that the drive motor (20) and the shafts (23, 27, 28) are mounted in the side walls.
13. Apparatus according to one of Claims 1 to 12, characterized in that the column frame (16) is substantially rectangular, in that four guide columns (18) are provided inside the column frame (16) and are positioned in the region of the four corners of the column frame (16), and in that the tensile forces are introduced into the top part (19) of the column frame (16) in each case in the immediate vicinity of the guide columns (18).
14. Apparatus according to one of Claims 1 to 12, characterized in that the tensile forces are introduced into the top part (19) of the column frame (16) in each case close to that point at which the forces for stamping or forming are required within the column frame (16).

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