EP2008735A1 - Machine tool and method for moving the workpiece part from a support to a discharge position - Google Patents

Abstract

The tool has motion units, which speeds up a support in a region of a workpiece part (12) with acceleration from a support position (P) along a gravitational force direction, where the acceleration is greater than the acceleration of workpiece part along the gravitational force direction. The motion units move the accelerated support with a speed along an open position such that the support is situated outside the line of motion of the workpiece part and the workpiece part achieves a transportation position (W) outdoors. An independent claim is also included for a method for passing a part of a plate-like workpiece e.g. steel sheet, from a support position into a transportation position.

Description

The invention relates to a machine tool for cutting a preferably plate-like workpiece, in particular a sheet, comprising: at least one support, which in a support position at its top supports a workpiece part completely cut from the workpiece, wherein the machine tool for bringing the workpiece part in a below the Exposed discharge position has a movement unit to move the support from the support position down. The invention also relates to a method for bringing one of a preferably plate-like workpiece, in particular a sheet, completely cut workpiece part from a support position in which the workpiece part at the top of a support located in a support position supports, located in a location below the support discharge position.

Generic prior art is known from JP 7214359 known. There, a workpiece part stored in a support position on the upper side of two supporting rows of oscillating arms, which are mounted opposite one another, is moved, after being cut free, into a discharge position below the supports, by the two rows of oscillating arms being pivoted downwards. The workpiece part is then moved by means of an unloading conveyor (conveyor belt) from the discharge position into a receiving position for receiving workpiece parts. When moving the workpiece part from the Aulfageposition in the discharge position, the workpiece part can slide on rollers, which are attached to the swing arms.

Generic prior art is further from the JP10118879 known. There, a workpiece part positioned in a support position on the upper side of a support located in a working plane is likewise brought into a discharge position situated below the working plane. For this purpose, the support is lowered down and thereby pivoted about an axis of rotation, whereby the workpiece part along the support slidably reaches a discharge position laterally offset discharge position.

Object of the invention

It is the object of the present invention to further develop a machine tool and a method of the generic type such that the workpiece part can be reliably moved downwards out of the support position and can reach the discharge position more quickly

Subject of the invention

According to the invention, this object is achieved by the fact that the movement unit is designed to accelerate the support at least in the region of the resting workpiece part with an acceleration in the direction of gravity from the support position, which is greater than the acceleration of the workpiece part in the direction of gravity, and that the movement unit is designed , the accelerated circulation at such a speed in an out of the way move the workpiece part located opening position that the workpiece part in free fall reaches the discharge position.

According to the invention it is proposed to spend the workpiece part in free fall in the discharge position. This has the advantage over a sliding or sliding movement that a movement in free fall is usually the fastest possible way to spend the workpiece part to a discharge position outside the processing area. In order to enable a movement in free fall, the support from the support position is accelerated faster down than the workpiece part itself, so that this lifts in the support position of the edition. As a result, the process reliability is increased because the workpiece part can not be offset laterally and so snagging on the remainder of the workpiece can be avoided. Subsequently, the support is moved from the movement path of the workpiece part in a typically laterally located opening position, which prevents the workpiece part after lifting again meets the support and undisturbed can reach the discharge position.

In an advantageous embodiment, at least one, preferably each support is pivotally mounted about a preferably perpendicular to the direction of gravity axis of rotation. In the support position, the support in this case is usually oriented horizontally to store the workpiece part at the top. The support is pivoted about the axis of rotation down to spend the workpiece part to the discharge position. In order to allow a free fall of the workpiece part from the support position, the support area of the workpiece part is arranged eccentrically to the rotation axis, so that the support during pivoting about the axis of rotation with a greater linear acceleration than the workpiece part itself can be accelerated. The linear acceleration of the support from the support position out in the direction of gravity increases with the distance to the axis of rotation, so that the torque to accelerate the support can be chosen the lower the greater the distance of the support region from the axis of rotation.

In a preferred development, at least one, preferably each support is motion-coupled to the movement unit via a connecting piece, which acts on the support eccentrically to its axis of rotation, that is, the movement unit engages not directly on the axis of rotation of the edition. Lever action is achieved by the connecting piece and the synchronous pivoting of several supports is facilitated, as explained in more detail below.

In an advantageous development, the movement unit has at least one guide displaceably guided in the direction of gravity, on which the connecting pieces are preferably guided linearly displaceable at right angles to the direction of gravity. By moving the guide in the direction of gravity by means of a common drive, the connecting pieces and thus the pads can be pivoted synchronously. The connectors are in this case forcibly guided on the guide and are preferably displaced in the horizontal direction during the displacement of the guide in the direction of gravity along the guide.

In a preferred embodiment of this embodiment, the connecting pieces are rotatably mounted on the supports and mounted non-rotatably on the common guide. This makes it possible that the connecting pieces are moved parallel to the pivoting of the pads and perform no rotational movement.

In a further advantageous development, a chute is provided on at least one of the connecting pieces, which protrudes at least in the opening position of the support in the movement path of the freely falling workpiece part. The provision of a chute on the connecting piece is advantageous because it is moved downward during pivoting of the support and laterally, whereby the chute can protrude into the movement path without additional aids in the opening position of the support. The provision of the chute is particularly advantageous if, in a partial region of the movement path, a structural unit such as, for a suction tube is mounted, which can be covered by the chute to prevent impact of the workpiece part on the assembly.

In a preferred embodiment, a fixed chute is provided for discharging the workpiece part from the discharge position. The fixed chute can in this case adjoin the chute attached to the connecting piece and both can together move the path of movement of the workpiece piece downwards limit, ie set the discharge position that reaches the workpiece part in free fall.

In a further advantageous embodiment, the or each support for accelerating from the support position in a linear movement in the direction of gravity can be lowered, wherein the linear movement is preferably over a distance of at most 5 mm, in particular of at most 2 mm. In this case, to accelerate the support, it is first moved parallel in the direction of gravity, whereby the workpiece part lifts off from the support. Subsequently, the support can be moved in different ways out of the movement path of the workpiece part in the direction of gravity, e.g. by the support is shifted at right angles to the direction of gravity. However, the above-described pivoting of the support about an axis of rotation preferably follows the linear movement in order to transfer the support into the opening position.

In a particularly advantageous embodiment, the or each support is biased in the support position by a biasing means in the direction of gravity. By biasing a large acceleration can be generated from the support position out. Preferably, the bias is generated by applying a force against the direction of gravity, which presses the pads against a force acting in the direction of gravity spring force or hydraulic force upwards.

In a further preferred embodiment, the movement unit has a common drive for the synchronous pivoting of the supports and preferably for the synchronous movement of the supports during the linear movement. By synchronous pivoting can be avoided that when accelerating the workpiece part from the support position out a lateral force is generated on the workpiece part, because the workpiece part of one of the pads stands out faster than the other. Furthermore, costs can be saved by the use of a common drive both for the pivoting and for the linear movement.

In a further preferred embodiment, the movement unit is designed to supply the or each support in the direction of gravity with an acceleration accelerate, which is greater than the gravitational acceleration and preferably at least two times, in particular at least three times the acceleration due to gravity. In general, the force acting on the workpiece part in the support position no additional force acting in the direction of gravity, so that the workpiece part is accelerated from the support position with the acceleration of gravity and lift the support to the workpiece part of the edition must be accelerated with slightly higher acceleration. However, it is favorable if, at least during the first movement phase, a high acceleration acts on the support, since it can subsequently be removed at a slower speed from the movement path of the workpiece part.

In a further advantageous embodiment, two supports are provided, which are mounted on opposite sides about preferably parallel, spaced-apart axes of rotation pivotably. The fall path of the workpiece part from the support position to the discharge position generally corresponds at least to the width of the support perpendicular to the axis of rotation, since this is usually pivoted by 80 ° or more in order to reach the opening position located outside the movement path. The width of the workpiece parts, which can be brought into the discharge position is limited by the width of the support. By providing two opposing supports, the width of the workpiece parts that can be moved to the discharge position can be increased without the fall path and thus the fall time being extended.

In a particularly advantageous embodiment, a suction opening is provided in the support for sucking off gases and / or rejects produced during the cutting process. The suction opening is usually arranged in a processing position of the machine tool, for example, below a laser processing head, and serves for discharging rejects as well as gases generated in the laser processing on the workpiece. For this purpose, the suction opening is usually connected to a suction device via a suction tube arranged under the support. When moving the support in the open position, the suction tube in the way and can be moved, for example by means of the drive described above down. The chute attached to the connecting piece can in this case be dimensioned such that it defines the pipe opening covers the suction tube when the support is in the open position.

In a further preferred embodiment, at least one sensor, preferably at least one light barrier, is provided for detecting the reaching of the discharge position by the workpiece part. Once the reaching of the discharge position has been detected, the support or pads can be moved from the open position back to the support position and the workpiece processing can be continued. As a result, the service life of the machine tool is reduced and at the same time the process reliability is increased, since the absence of the detection signal generates an error signal and the further processing can be initially set to avoid damage. Preferably, a series of light barriers arranged side by side is used which form a light grid for monitoring a surface area at the discharge position.

In a further preferred embodiment, the support in the support position at least partially closes an opening in a processing table of the machine tool. The support here is usually aligned horizontally in the support position and arranged at the height of the editing table. Optionally, however, the support position may also be defined at a position below the work table, e.g. if initially a slow lowering of the support should be done with the workpiece part mounted on the top.

In a further advantageous embodiment, at least one support is attached to a displacement device for displacing the support along the processing table. In this case, at least one further, the movable support opposite support is usually mounted on the machining table. The movable support can be moved out of a position in which it adjoins the additional support and together with this closes the opening in the processing table, be moved by means of the displacement device of the further support away, so that a gap arises between them. This is favorable if workpiece parts are to be brought into the discharge position, which have a greater width in the direction of displacement than the sum of the widths of the two supports. In this case, the movable support is moved until the workpiece part only at its opposite ends on the two pads and not on rests on the working table. Once the slidable flap has reached such a position, the pads are accelerated out of the support position as described above.

According to the invention, the object is achieved by a method with the following steps: accelerating the support from the support position at least in the region of the resting workpiece part in the direction of gravity with an acceleration that is greater than an acceleration of the workpiece part in the direction of gravity, and moving the accelerated support with a such speed in an opening position located outside the movement path of the workpiece part that the workpiece part reaches the discharge position in free fall. The inventive method makes it possible to spend the workpiece part quickly and safely to the discharge position.

For this purpose, the or each support for accelerating from the support position is preferably lowered in a linear movement in the direction of gravity, wherein the linear movement is preferably over a distance of at most 5 mm, in particular of at most 2 mm. By the linear movement and workpiece parts can be lifted from the top of the support, which are arranged at the top of the support in the vicinity of the axis of rotation, which would require a very high acceleration in a pure rotary motion.

In a particularly advantageous variant, one, preferably each support is pivoted about a preferably perpendicular to the direction of gravity axis of rotation to accelerate the support at least in the region of the resting workpiece part and / or to move the accelerated support in an out of the movement path of the workpiece part opening position. Particularly advantageous is a combination of a linear movement in which the workpiece part is lifted from the support and a subsequent rotational movement to move the support out of the movement path of the workpiece part.

Further advantages of the invention will become apparent from the description and the drawings. Likewise, the features mentioned above and those listed in more detail may be used individually or in any combination Find. The embodiments shown and described are not meant to be conclusive but rather have exemplary character.

Fig. 1

eine schematische Darstellung einer Ausführungsform einer erfindungsgemäßen Werkzeugmaschine mit zwei Auflagen,

Fign. 2a-c

schematische Darstellungen von Ablaufschritten einer Variante des erfindungsgemäßen Verfahrens zum Verbringen eines Werkstückteils aus einer Auflageposition in eine Abfuhrposition,

Fign. 3a,b

schematische Darstellungen von Teilansichten der Werkzeugmaschine von Fig. 1 mit den zwei Auflagen in einer Auflageposition, und

Fig. 4

eine schematische Darstellung einer Teilansicht der Werkzeugmaschine von Fig. 1 mit den zwei Auflagen in einer Öffnungsposition.

Show it:

Fig. 1

1 is a schematic representation of an embodiment of a machine tool according to the invention with two supports,

FIGS. 2a-c

schematic representations of operational steps of a variant of the inventive method for moving a workpiece part from a support position to a discharge position,

FIGS. 3a, b

schematic representations of partial views of the machine tool of Fig. 1 with the two pads in a pad position, and

Fig. 4

a schematic representation of a partial view of the machine tool of Fig. 1 with the two pads in an open position.

Fig. 1 shows a trained as a laser punch press machine tool 1 , which has a conventional punching device 3 and a laser processing head 4 as tools for processing a sheet serving as a workpiece 2 . The workpiece 2 to be machined supports on a processing table 5 during workpiece machining. By means of a conventional holding device 6 , which has clamps 7 for holding the workpiece 2, the workpiece 2 can be displaced relative to the stationary punching device 3 and the laser processing head 4 in the X direction of the sheet plane (XY plane of an XYZ coordinate system). In the Y-direction of the sheet plane, the workpiece 2 can be moved by displacing the machining table 5 together with the holding device 6 relative to a base 8 on which the working table 5 is supported by means of a conventional coordinate guide (not shown).

The workpiece 2 can thus be moved in the X and Y directions relative to the punching device 3 and the laser processing head 4, so that each to machining area of the workpiece 2 in a stationary processing area 9 of the punching device 3 and a limited by a substantially circular suction opening 10 in the processing table 5 processing area 11 of the laser processing head 4 can be spent. The suction opening 10 serves for the extraction of gases generated during workpiece machining by the laser processing head 4 and of reject parts. The portion of the workpiece table 5 in the X direction, on which the processing areas 9, 11 are formed, is stationary and is not displaced in the Y direction relative to the base 8, so that the suction opening 10 is always positioned below the laser processing head 4.

After a region of the workpiece 2 to be processed has been brought into the processing region 11 of the laser processing head 4, as shown above, the latter is activated in order to completely cut out, for example, a rectangular workpiece part 12 from the workpiece 2. After the free cutting, the workpiece part 12 rests in the sheet plane on two adjacent, positioned in the sheet metal supports 13a, 13b in the form of flaps. The first support 13 a is arranged directly below the laser processing head 4 and has the suction opening 10 defining the processing region 11.

To bring the workpiece part 12 out of the plane of the sheet into a discharge position (not shown) located below the sheet plane, the supports 13a, 13b can be pivoted on opposite sides 14a, 14b about two parallel axes of rotation 15a, 15b . The axes of rotation 15a, 15b are in this case arranged at a distance which is twice the width (2 b ) of the two supports 13a, 13b in the Y direction. Workpiece parts which are dimensioned larger in the Y-direction than this distance can be used for the in Fig. 1 shown positioning of the pads 13a, 13b are not spent in the discharge position.

In order to spend larger sized workpiece parts in the discharge position, the second support 13b is attached to a displacement device 16 in the form of a sliding table and can be moved together with this in the Y direction in the sheet plane. This increases the distance between the two axes of rotation 15a, 15b in the Y direction and between the two supports 13a, 13b, an opening (not shown) is formed in the processing table 5. The second edition 13b is in this case postponed until the workpiece part rests only at its opposite ends on the upper sides of the two supports 13a, 13b and no longer on the workpiece table 5 itself.

The movement of the workpiece part 12 from a support position P into an underlying discharge position W will be described below with reference to FIG FIGS. 2a -c , which schematically show process steps of the movement of the pads 13a, 13b in this process, the second flap 13b in the Y direction as in FIG Fig. 1 is shown positioned. In Fig. 2a are the supports 13a, 13b at the support position P in the sheet metal plane of the machining table 5 and the workpiece part 12 is mounted on the upper sides. To spend the workpiece part 12 in free fall to the discharge position W, the two supports 13a, 13b from the support position P out with an acceleration a _A in gravitational force 17 (corresponding to the negative Z direction) linearly accelerated downwards, which is three times the force acting on the workpiece part 12 gravitational acceleration a _G corresponds. Due to the linear movement of the supports 13a, 13b down over a distance d of about 3 mm, the workpiece part 12 is lifted from the supports 13a, 13b, as in Fig. 2b is shown. Subsequently, the two supports 13a, 13b pivoted about their respective axes of rotation 15a, 15b, as indicated by arrows in Fig. 2b indicated, and thereby moves into an out of movement path 18 of the workpiece part 12 located opening position O, the in Fig. 2c is shown. In this way, the workpiece part 12 can reach its discharge position W in free fall, from which the workpiece part 12 can subsequently be removed from the machine tool 1.

It is understood that as an alternative to the above-described movement of the supports 13a, 13b, which is composed of a linear movement and a pivoting, the same result can be achieved only by pivoting the supports 13a, 13b. In this case, the acceleration required to lift the workpiece part 12 off the supports 13a, 13b without sliding along the supports 13a, 13b depends on its distance from the respective axes of rotation 15a, 15b. The smaller the distance of the workpiece part 12 from the axes of rotation 15a, 15b, the greater the acceleration in the pivoting must be selected.

Further alternatively to in connection with Fig. 2 described motion sequence, the workpiece part 12 initially on the upper side of the pads 13a, 13b stored by means of a linear movement by a distance of eg a few millimeters are moved to a support position below the sheet metal plane to avoid entanglement of the workpiece part (not shown) remaining workpiece , From this lowered position out of the above movement can then be performed. It is understood that, alternatively to the pivoting of the supports 13a, 13b, they can also be moved in another way out of the movement path 18 of the workpiece part 12, eg in a linear movement perpendicular to the direction of gravity 17.

The following is based on the FIGS. 3a , b and Fig. 4 which each detail views of a lower part of the machine tool 1 of Fig. 1 show how the in FIGS. 2a-c described sequence of movements can be realized structurally. For this purpose, in the machine tool 1, an in Fig. 3a shown movement unit, which has an electric motor drive 19 which is coupled via a toothed belt 20 with a guided in an overload-proof bearing 21 threaded spindle 22 . The threaded spindle 22 of the movement unit has a spindle nut 23 , which can be moved in and against the direction of gravity 17. The spindle nut 23 is attached to a guide 24 , which in turn is guided in a longitudinal plate 25 in and against the direction of gravity 17 linearly displaceable.

As in Fig. 3b shown, the guide 24 has a horizontally extending guide rail 27 , in which two connecting pieces 28a, 28b are guided linearly displaceable. The connecting pieces 28a, 28b respectively engage the supports 13a, 13b in an eccentric manner relative to the axes of rotation 15a, 15b and are rotatably mounted on them while they are guided non-rotatably along the guide rail 27. If the spindle nut 23 is moved downward by means of the drive 19, the guide 24 is lowered and the connecting pieces 28a, 28b guided on the guide rail 27 are entrained. During this movement, the connecting pieces 28a, 28b are displaced horizontally along the guide rail 27 due to the non-rotatable mounting. Due to the eccentric to the axes of rotation 15 a, 15b attacking connectors 28a, 28b, the pads 13a, 13b are pivoted downward from its horizontal position during this movement.

In addition to the pivoting movement, the linear movement in the first part of in FIGS. 2a-c To realize the sequence of movements shown, it is necessary to move the axes of rotation 15a, 15b in or against the direction of gravity 17. This is accomplished by moving the connectors 28a, 28b further upwardly than would be required for the horizontal alignment of the pads 13a, 13b. The supports 13a, 13b are in this case pressed against a (not shown) stop, which prevents pivoting of the pads 13a, 13b from the horizontal position upwards. In this case, a force is exerted on the supports 13a, 13b and thus also on the bearings of the axes of rotation 15a, 15b.

As in Fig. 3a shown, the axis of rotation 15a is rotatably mounted on a support plate 29 extending in a vertical, ie in the direction of gravity 17. The support plate 29 is guided on a further, also in the direction of gravity 17 extending plate 30 of a (not shown) transverse frame and under application of a force against the direction of gravity 17 by means of a Anschageinheit 31 prestressed, which (not shown) spring unit as a shock absorber and a (not shown) has hydraulic piston. The support plate 29 and thus the bearing of the axis of rotation 15a is pressed by the force applied by the connecting pieces 28a, 28b against the direction of gravity 17 force against the force acting in the direction of gravity 17 spring or hydraulic force upwards, typically with a stroke of approx. 3-5 mm.

If the connecting pieces 28a, 28b are moved downwards in the supporting position by the drive 19, the rotational axes 15a, 15b move downwards synchronously due to the pretension, so that the supports 13a, 13b are parallel in a linear movement over the distance of the pretensioning move to the plate plane. By further moving the connecting pieces 28a, 28b downwards, the above-described pivoting of the supports 13a, 13b directly follows the linear movement. The speed of pivoting is in this case matched to the previous linear movement, that the workpiece part after lifting can no longer impinge on the supports 13a, 13b.

Fig. 4 shows the pads 13a, 13b after completion of the above movement in an open position in which they have been completely pivoted and enclose an angle of approximately 80 ° with the plane of the sheet. To a workpiece part after the in FIGS. 2a-c shown to dissipate free falling movement of the work area of the machine tool 1, a chute 32 is attached to the first connector 28 a, as well as in Fig. 3b can be seen more clearly. By the parallel displacement of the connecting piece 28a, the chute 32 is taken down and protrudes in the opening position of the supports 13a, 13b in the (not shown) movement path of the workpiece part. At the connection piece 28a mounted chute 32 includes in the opening position of the supports 13a, 13b directly to a solid chute 33 at. A free-falling workpiece part thus meets at its discharge position either on the fixed chute 33 or on the first connector 28 a fixed, hereinafter referred to as movable chute 32 and can be removed in a sliding movement of the working area of the machine tool 1.

The movable chute 32 provided in addition to the fixed chute 33 is required to cover a suction pipe 34 which in the supporting position communicates with the suction opening 10 of the first support 13a. The suction pipe 34 is located at the in Fig. 3a attached spindle nut 23 is fixed and is taken along with their displacement in the direction of gravity 17 down. An end piece 35 of the suction tube 34 is attached to the first support 13a and is pivoted therewith, as in FIG Fig. 4 is shown. In the suction tube 34, a (not shown) beam catcher is provided at the lower end to intercept the laser beam passing through the suction opening 10 laser beam.

The reaching of the discharge position of a workpiece part is detected by a light grid 36 , which is formed in the horizontal direction at the level of the transition between the fixed chute 33 and the movable chute 32 by a series of light barriers. The light barriers each consist of a light source 37 and an associated sensor 38 . It is understood that the discharge position at which the workpiece part in free fall impinges on the chutes 32, 33, depends on the dimensioning of the workpiece part, ie, the workpiece part may optionally First completely impinge on the moving chute 32 and only pass the light grid 36 when sliding down on the solid chute. Although the pads 13a, 13b should be moved back to the starting position as soon as possible after detecting the workpiece part at the discharge position in order to resume workpiece machining as quickly as possible, but can be prevented by the arrangement of the light grid 36 below the movable chute 32 that the support 13a is pivoted upwards too early and if necessary entrains a workpiece part still resting on it.

It is understood that the movement described above can be found not only for the removal of workpiece parts from the processing area 11 of the laser processing head 4, but also for discharging workpiece parts from the processing area 9 of the punching device 3 use. Furthermore, a discharge in the manner described above can also be used advantageously on other machine tools, for example on stamping and bending machines, in which the workpiece parts are still bent after the free cutting, before they are moved out of the support position into the discharge position.

Claims (19)

Machine tool (1) for cutting a preferably plate-like workpiece (2), in particular a sheet, comprising: at least one support (13a, 13b) which supports a workpiece part (12) which is completely cut free from the workpiece (2) in a support position (P) on its upper side, wherein the machine tool (1) for moving the workpiece part (12) into a discharge position (W) located below the support (13a, 13b) has a movement unit (19 to 24) for moving the support (13a, 13b) from the support position (P ) to move down, characterized, in that the movement unit (19 to 24) is designed to accelerate the support (13a, 13b) at least in the region of the resting workpiece part (12) with an acceleration (a _A ) in the direction of gravity (17) from the support position (P) is as the acceleration (a _G ) of the workpiece part (12) in the direction of gravity (17), and that the movement unit is adapted (19 to 24), the accelerated support (13a, 13b) located at such a rate into an out of the path of movement (18) of the workpiece part (12) opening position to move (O), that the workpiece part (12) in free fall reaches the discharge position (W). Machine tool according to claim 1, wherein at least one, preferably each support (13a, 13b) about a preferably perpendicular to the direction of gravity (17) extending axis of rotation (15a, 15b) is pivotally mounted. Machine tool according to Claim 2, in which at least one, preferably each support (13a, 13b) is motion-coupled to the movement unit (19 to 24) via a connecting piece (28a, 28b) which bears on the support (13a, 13b). 13b) acts eccentrically to the axis of rotation (15a, 15b). Machine tool according to claim 3, wherein the movement unit (19 to 24) at least one in the direction of gravity (17) slidably guided guide (24) on which the connecting pieces (28a, 28b) are preferably guided linearly displaceable perpendicular to the direction of gravity (17). Machine tool according to claim 4, wherein the connecting pieces (28a, 28b) on the supports (13a, 13b) are rotatably mounted and non-rotatably on the common guide (24). Machine tool according to one of claims 3 to 5, wherein at least one of the connecting pieces (28a) a chute (32) is provided, which at least in the opening position (O) of the support (13a) in the movement path (18) of the free-falling workpiece part (12) protrudes. Machine tool according to one of the preceding claims, wherein a fixed chute (33) is provided for discharging the workpiece part (12) from the discharge position (W). Machine tool according to one of the preceding claims, wherein the or each support (13a, 13b) for accelerating from the support position (P) in a linear movement in the direction of gravity (17) can be lowered, wherein the linear movement preferably over a distance of at most 5 mm, in particular of at most 2 mm. Machine tool according to one of the preceding claims, wherein the or each support (13a, 13b) in the support position (P) by a biasing means (31) in the direction of gravity (17) is biased. Machine tool according to one of the preceding claims, in which the movement unit (19 to 24) has a common drive (19) for synchronously pivoting the supports (13a, 13b) and preferably for synchronously moving the supports (13a, 13b) during the linear movement. Machine tool according to one of the preceding claims, wherein the movement unit (19 to 24) are adapted to accelerate the or each support (13a, 13b) in the direction of gravity (17) with an acceleration which is greater than the gravitational acceleration and preferably at least that Twofold, in particular at least three times the acceleration due to gravity. Machine tool according to one of the preceding claims, in which two supports (13a, 13b) are provided, which are mounted on opposite sides (14a, 14b) pivotable about preferably parallel, spaced apart rotational axes (15a, 15b). Machine tool according to one of the preceding claims, wherein in the support (13a) is provided a suction opening (10) for sucking off gases and / or rejects produced during the cutting process. Machine tool according to one of the preceding claims, wherein for detecting the reaching of the discharge position (W) of the workpiece part (12) at least one sensor, preferably at least one light barrier (37, 38) is provided. Machine tool according to one of the preceding claims, wherein the support (13a, 13b) in the support position (P) at least partially closes an opening in a processing table (5) of the machine tool (1). Machine tool according to claim 15, wherein at least one support (13b) on a displacement device (16) for moving the support (13b) along the processing table (5) is attached. Method of transferring a workpiece part (12) which has been completely cut free from a preferably plate-like workpiece (2), in particular a metal sheet, from a support position (P) in which the workpiece part (12) bears on the upper side of at least one support (13a, 13b), in a below the support (13a, 13b) located discharge position (W), comprising the steps: Accelerating the support (13a, 13b) from the support position (P) at least in the region of the resting workpiece part (12) in the direction of gravity (17) with an acceleration (a _AF ) which is greater than an acceleration (a _w ) of the workpiece part (12 ) in the direction of gravity (17), and Moving the accelerated support (13a, 13b) at such a speed into an opening position (O) located outside the movement path (18) of the workpiece part (12) that the workpiece part (12) reaches the discharge position (W) in free fall. Method according to Claim 17, in which the or each support (13a, 13b) is lowered for acceleration from the support position (P) in a linear movement in the direction of gravity (17), the linear movement preferably over a distance of at most 5 mm, in particular of 2 mm at the most. A method according to claim 17 or 18, wherein one, preferably each support (13a, 13b) is pivoted about a preferably perpendicular to the direction of gravity (17) extending axis of rotation (15a, 15b) to the support (13a, 13b) at least in the region of to accelerate resting workpiece part (12) and / or the accelerated support (13a, 13b) in an out of the movement path (18) of the workpiece part (12) located to move opening position (O).

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