EP1810761A1 - Sheet folding device - Google Patents

Abstract

Device for folding sheet metal comprises a lower part which can be adjusted together with a bending part (4) in the sheet metal support surface defined by the lower part at a right angle to the bending edge (3.1) of an upper part (3) in a Y-direction.

Description

The invention relates to a Blechabkantvorrichtung, with a lower cheek, an ascertainable in a Z-direction upper cheek, which has a bending edge with a radius R, and with a bending cheek, which is at least approximately coinciding with an edge of the lower cheek facing the bending edge, in an X-direction axis is pivotable via a drive.

Blechabkant- or sheet metal bending devices of the aforementioned type are known in numerous embodiments. Mostly they are hydraulically driven large machine tools with working widths up to several meters, which require a considerable footprint, are hydraulically driven, have a high electrical connection capacity and weigh several tons. The use of such large devices also for folding or bending the often required small sheet metal parts, whose dimensions go down to the millimeter range, is common practice, but very uneconomical. For folding usually the upper beam is moved to the plate thickness up to their working position, then moved to insert sheets further up and then lowered to clamp the sheet back in the direction of the lower beam in the working position. The bending cheek, more precisely their surface causing the folding, is usually moved downwards relative to the surface of the lower cheek, on which the sheet rests, around the sheet thickness and then pivoted about the predetermined bending angle. This design principle limits the use of such devices on the bending or bending of sheet metal parts in which a large tolerance range is permitted for the bending angle. A further disadvantage is that the hydraulic drives do not readily permit the scaling-down of such a device which is desirable for small sheet-metal parts.

The invention has for its object to provide a Blechabkantvorrichtung the introductory genus, which is suitable for folding or bending of particular small sheet metal parts with improved accuracy of the angle of the fold or the so-called. Bugs.

This object is achieved in that the lower beam is adjustable together with the bending beam in the defined by the lower cheek plate support plane perpendicular to the bending edge of the upper beam in a Y-direction by an adjustable dimension m.

The sheet support surfaces, on the one hand the lower beam, on the other hand, the bending beam in its initial position before pivoting, remain in the same (horizontal) plane.

One of the essential tool movements is thus carried out instead of in a vertical in a horizontal plane, wherein the working position of the upper beam and thus the position of the bending edge in relation to a base plate or a base frame of the device remains stationary. With this simplified construction of the upper beam, the overall height of the device can be reduced, so that in place of a "standing" a "lying" construction with compact dimensions, eg in the form of a device on a workbench, can occur. The adjustability of the lower cheek and the bending cheek in lying in a horizontal plane Y-direction leads to better bending results by a dependent on the strength of the sheet to be bent or abzukantenden adjustment. Furthermore, this construction allows for a large, perpendicular to the working width depth of the bearing surface of the sheet on the lower beam, which also benefits the quality of the executed folds.

worin

m

der Abstand der Schwenkachse der Biegewange von der Biegekante

R

der Radius der Biegekante

S

die Stärke (Dicke) des Blechteiles

α

der Schwenkwinkel der Biegewange

sind.Optimal work results, ie accurate and reproducible folds or bows, in particular also small sheet metal parts are achieved according to the invention, when the adjustment of the lower beam and the bending beam against the bending edge of the upper beam, the radius of the bending edge, the sheet thickness and the pivot angle of the bending beam are taken into account. This pivot angle of the bending cheek is known to be larger than the bending angle of the finished part to the springback angle of the sheet metal part. The best work result is achieved when the adjustable dimension m is given by the adjustment $$m=\frac{R+S}{\tan \left(\alpha /2\right)}-R;$$

wherein

m

the distance of the pivot axis of the bending beam from the bending edge

R

the radius of the bending edge

S

the thickness of the sheet metal part

α

the swing angle of the bending beam

are.

The adjustability of the lower cheek and the bending cheek against the bending edge can be achieved in particular by the fact that the lower cheek and the bending cheek are arranged on a carriage which is movable relative to the upper beam.

Preferably, the carriage is movable via two carriage drives arranged symmetrically with respect to the vertical center plane of the device containing the Y direction, each of which comprises a stepper motor with spindle nut and a threaded spindle engaging on the carriage. The drive of the carriage by means of the symmetrically arranged stepper motors in conjunction with digital displacement transducers has the advantage that the carriage is tilt-free and can be moved very accurately.

A particularly compact and space-saving, especially as a desktop device executable embodiment, therefore, for cost-effective bending or bending of small sheet metal parts with dimensions between a few millimeters and, for. 100 to 200 mm, is characterized by the fact that the drive of the bending cheek consists of one stepper motor with downstream gear on each side of the bending cheek. This is contrary to a design as Tischabkantvorrichtung, on the one hand, because the reduction of the usual hydraulic drive, in particular the bending beam limits are set, on the other hand, because the two-sided drive the bending beam both the motor torque to be generated as well as the twisting of the bending beam to their in the X direction extending pivot axis bisected. The latter has the advantage that the bending cheek and its bearings can be performed with the same angular accuracy of the fold correspondingly less massive than in a single-sided motor drive the bending cheek. The use of digital angle encoders ensures that the two stepper motors are controlled exactly synchronously.

Preferably, the upper beam is exchangeably received in a Oberwangenkassette which is pivotable about an axis extending in the X direction. The delivery of the upper beam in the direction of the lower beam for clamping the sheet is so realized by a pivoting movement of Oberwangenkassette. This feature also helps to keep the overall height of the device small relative to its working width.

Expediently engages for clamping the sheet between the lower cheek and the upper cheek on both sides of the upper cheek cartridge per an adjustable via an electric motor and an eccentric pull rod. The symmetrical arrangement of the electric motors in this case too, which need not be stepper motors in this case, has the same advantages as explained above in connection with the drive of the bending beam. The two electric motors can be arranged to save space in a plane between the base plate and the working or Blechauflageebene. This also favors a compact design.

With particular advantage, the upper cheek box can be arranged offset parallel to the lower cheek in the Y direction. This allows the use of upper cheeks, which have the shape of flat, in the direction of the bending edge wedge-shaped tapered plates. In addition to the advantage of the low overall height of the device thereby a large bending angle of, for example, more than 120 ° is made possible.

Preferably, an adjustable via an electric motor with spindle nut and a threaded spindle, interchangeable stop rule is arranged between the upper beam and the lower beam. If the electric motor is designed as a stepper motor, the leg length of abzukantenden or to be bent plate can be set exactly via the machine control.

Zweikmäßig the upper beam, apart from its deliverability, arranged on a base plate or a base frame.

The basic design principle of the device is that for all drives electric motors, mainly stepper motors, are used and that all drives are arranged symmetrically to the Y-direction containing, vertical center plane of the device. In addition to the advantages already mentioned in mechanical terms, it is also achieved that all working parameters and working movements of the device can be programmed, executed and monitored by means of a machine control.

Fig. 1

eine Teilansicht der Unterwange, der Oberwange und der Biegewange sowie ein Blechteil im Schnitt,

Fig. 1a

den Bereich im strichpunktierten Kreis in Fig. 1 in vergrößertem Maßstab,

Fig. 2

eine perspektivische Ansicht der gesamten Vorrichtung,

Fig. 3

die gleiche Ansicht nach Entfernung einer Seitenwange und an dieser befestigter Antriebsteile,

Fig. 4

eine perspektivische Aufsicht auf die Vorrichtung in Fig. 2,

Fig. 5

eine zu Fig. 3 korrespondierende Aufsicht auf die Vorrichtung.

In the drawing, an embodiment of a device according to the invention is shown. It shows:

Fig. 1

a partial view of the lower beam, the upper beam and the bending beam and a sheet metal part in section,

Fig. 1a

the region in the dot-dashed circle in Fig. 1 on an enlarged scale,

Fig. 2

a perspective view of the entire device,

Fig. 3

the same view after removal of a side wall and at this fixed drive parts,

Fig. 4

a perspective view of the device in Fig. 2,

Fig. 5

a corresponding to Fig. 3 supervision of the device.

Fig. 1 shows a simplified side view in a sectional view of a lower beam 2, a lowered to this for clamping a sheet metal part 30 upper beam 3 and a bending cheek 4, which has already carried out the bending of the sheet metal part 30 by an angle with the bisector w.

$$\frac{R+S}{\tan \left(\beta /2\right)}=R+m;$$

aus β = 180°-α folgt β/2 = 90°-α/2;
damit wird Gleichung (2) zu $$m=\frac{R+S}{\tan \left(90°-\alpha /2\right)}-R;$$

Fig. 1a illustrates the geometric relationships in the Abkantbereich. The sheet metal part 30 has a thickness or thickness S and is bent along an edge of a bend 3.1 with an inner radius which is equal to the radius R of the bending edge 3.1 of the upper beam 3, by an angle α. The angle α is shown to better illustrate the relationship developed below as a pivot angle between the not shown in the starting position of the bending beam 4 abutting surfaces of the lower beam 2 and the bending cheek 4. The swivel angle α is not to be confused with the later bending angle, which is usually smaller than the swivel angle α or larger than its opposite angle β, namely the amount of springback of the folded leg of the sheet metal part 30. The bisector w of the swivel angle α and accordingly Its opposite angle β also passes through the center of curvature with the radius R, which is the inner radius of the sheet metal part 30 in the bending area and at the same time the outer radius of the bending edge 3.1. From this, the optimum dimension m, by which the pivot axis A of the bending cheek 4 is spaced from the bending edge 3.1, can be determined as follows: $$\frac{R+S}{R+m}=\tan \left(\beta /2\right);$$

$$\frac{R+S}{\tan \left(\beta /2\right)}=R+m;$$

from β = 180 ° -α, β / 2 = 90 ° -α / 2;
thus equation (2) becomes $$m=\frac{R+S}{\tan \left(90°-\alpha /2\right)}-R;$$

The equation (3) provides as a measure m the distance that the pivot axis A of the bending beam 4 must have from the bending edge 3.1 depending on the bending radius, the sheet thickness and the swivel angle, so that against the lower surface of the sheet metal part 30 fitting surface of the bending beam 4 to At the end of the pivoting movement, it is flush with this surface of the sheet-metal part 30. This ensures optimal Abkantbedingungen and therefore compliance with a prescribed bending angle with close tolerance.

Fig. 2 shows an executed according to this principle table machine with a base plate 1, the upper beam 3 with the bending edge 3.1 and the bending cheek 4. The lower beam is hidden in this illustration by the upper beam 3 and the bending beam 4. The bending cheek 4 is rotatable between side cheeks 5a and 5b about the pivot axis A, which coincides with the bending edge 3.1 facing edge of the bending surface 4.1 of the bending cheek 4. For this purpose, pivot levers 4.2a and 4.2b (see Fig. 3), which are mounted in the side cheeks 5a and 5b and connected to the driven side of gears 6a and 6b, engage on the stepping motors 7a on both sides of the (preferably exchangeable) bending cheek 4 and 7b are flanged.

Fig. 3 shows the device after removal of the side cheek 5b, the transmission 6b and the stepping motor 7b and with removed upper cheek 3 and arranged underneath but also removed stop ruler 17, so that the lower cheek 2 and the pivot lever 4.2a, 4.2b are recognizable , The lower cheek 2 is attached to the side cheeks 5a and 5b. The latter form together with a cross bar 8 a slide, which is guided over rails 9a, 9b on the base plate 1 and against this by means of stepper motors 10a and 10b and on the cross bar 8 engaging threaded spindles and guide columns 11a and 11b in the Y direction is movable. About the synchronously controlled stepping motors 10a and 10b are the lower beam 2 and the bending beam 4 relative to the bending edge 3.1 in Fig. 2 by the respectively according to equation (3) determined dimension m, which may for example be between the zero position and 10 mm, jointly adjustable.

The upper beam 3 in Fig. 2 is interchangeable received in a cassette 12. The cassette 12 is pivotally mounted with double-sided bearing pin as 12b in Fig. 2 and 3 in two-sided bearing blocks 13a and 13b, which are fixedly connected to the base plate 1. For pivoting the upper cheek cartridge 12 on its receiving plate 12.1 on both sides of blocks 12.1a and 12.1b, where pull rods 14a and 14b attack, the other, lower ends with an eccentric gear as 15b in Fig. 3 are connected. The eccentric gears are actuated by electric gear motors 16a and 16b to lift the upper beam 3 for inserting a sheet metal part 30 in Fig. 1 of the lower beam 2 and deliver for clamping the sheet metal part back to the lower beam 2.

As a result of the upper cheek cartridge 12, which is set back far opposite the bending edge 3.1 in FIG. 2, the exchangeable upper cheek 3 can consist of the illustrated, flat plate, which tapers in a wedge shape in the direction of the bending edge 3.1. Therefore, the bending cheek 4 can have a large tilting angle, e.g. more than 120 °, before the bent leg of the sheet metal part collides with the upper beam 3.

For exact determination of the clamping depth of the sheet metal part, the abovementioned stop rule 17 is arranged between the upper beam 3 in Fig. 2 and the lower beam 2 in Fig. 3. The stop rule 17 is interchangeable on a support 18, which in turn is adjustable via a spindle 19 and a stepper motor 20 with a spindle nut in the Y direction. The stepper motor 20 has a support block 21, which with the Base plate 1 is screwed and also receives sliding bushes for the guide columns 11 a and 11 b.

All motors are connected to a control, not shown, which simultaneously receives the actual positions of the moving parts of the device of known per se and therefore not shown path and angle sensors, so that the device can be operated completely programmatically.

FIGS. 4 and 5 show, for the sake of greater clarity, other views of the device described, namely, FIG. 4 a front view obliquely from above, and FIG. 5 a plan view.

Claims (10)

Blechabkantvorrichtung, with a lower cheek (2), one of these deliverable in a Z-direction upper cheek (3) which has a bending edge (3.1) with a radius R, and with a bending cheek (4) which is one with the bending edge ( 3.1) facing edge of the lower cheek at least approximately coincident, extending in an X direction mechanical axis via a drive is pivotable, characterized in that the lower cheek (2) together with the bending cheek (4) in the plane defined by the lower cheek (2) sheet support plane at right angles to the bending edge (3.1) of the upper beam (3) in a Y-direction by an adjustable amount m is adjustable. Apparatus according to claim 1, characterized in that the adjustable dimension m of the adjustment is given by $$m=\frac{\left(R+S\right)}{\tan \left(\alpha /2\right)}-R;$$

wherein m the distance of the pivot axis of the bending beam (4) from the bending edge (3.1) R the radius of the bending edge (3.1) S the thickness of the sheet metal part (30) α the swing angle of the bending beam (4) are. Apparatus according to claim 1 or 2, characterized in that the lower cheek (2) and the bending cheek (4) on a carriage (5a, 5b, 8, 11a, 11b) are arranged, which is opposite the upper beam (3) movable. Apparatus according to claim 3, characterized in that the carriage (5a, 5b, 8, 11a, 11b) is movable over two carriage drives arranged symmetrically to the median plane of the device containing the Y-direction, each of which has a stepping motor (10a, 10b). comprising a spindle nut and an engaging on the carriage threaded spindle. Device according to one of claims 1 to 4, characterized in that the drive of the bending cheek (4) consists of a respective stepper motor (7a, 7b) with downstream transmission (6a, 6b) on each side of the bending cheek (4). Device according to one of claims 1 to 5, characterized in that the upper cheek (3) is interchangeably accommodated in a top cheek cartridge (12) for clamping the sheet metal part (30) against the lower cheek (2) about an axis extending in the X direction is pivotable. Apparatus according to claim 6, characterized in that for clamping the sheet metal part (30) between the lower beam (2) and the upper beam (3) on each side of the Oberwangenkassette (12) via an electric motor (10a, 10b) and an eccentric (15b ) adjustable pull rod attacks. Apparatus according to claim 6 or 7, characterized in that the upper cheeks cassette (12) opposite the lower cheek (2) is arranged offset in parallel in the Y direction. Device according to one of claims 1 to 8, characterized in that between the upper beam (3) and the lower beam (2) via an electric motor (20) with a spindle nut and a threaded spindle (19) adjustable, replaceable stop rule (17) is arranged. Device according to one of claims 1 to 9, characterized in that the upper cheek (3) apart from a deliverability for clamping of the sheet metal part (30), fixed on a base plate (1) is arranged.

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