DE102018203061A1 - Method for finding a suitable holding position - Google Patents

Abstract

The invention relates to a method for finding at least one suitable holding position (HP) for at least one holding device (26) having a plurality of holding elements (34) relative to a by means of the holding device (26) to be moved on a workpiece support or one by means of Holding device (26) to be supported workpiece part (16), comprising: a) defining a holding position (HP) of the holding device (26) in which at least one holding element (34) at least partially overlaps with the workpiece part (16) to an effective holding element (34a) acting on the workpiece part (16); b) determining a resultant force exerted by the workpiece part (16) upon translation or wear on a respective effective support member (34a); c) evaluating the hold position (HP) as appropriate for the shifting or the carrying of the workpiece part (16), if for each effective holding elements (34 a) in each case on the workpiece to be moved il (16) in the displacement direction (Y) transmittable transverse force or a respectively on the workpiece to be supported part (16) transferable in a transport direction holding and / or transverse force meets a dependent of the resultant force evaluation criterion.

Description

The present invention relates to a method for finding at least one suitable holding position for at least one holding device, which has a plurality of holding elements, relative to a by means of the holding device on a workpiece support (side) or to be supported by the holding device, usually plate-shaped workpiece part. The invention also relates to a computer program product for carrying out such a method.

If a workpiece part separated from a plate-shaped workpiece is to be displaced laterally by means of a holding device alone or together with the surrounding residual grid on a workpiece support, the workpiece part can slip relative to the holding device and / or relative to the residual grid. Likewise, a displacement of the workpiece part relative to the residual grid may occur if, at the moment of free-cutting, forces (for example the force of an acting cutting gas during laser cutting) act on the workpiece part. A relative to the holding device or the skeleton displaced workpiece part may possibly be difficult or not automatically removed from the machine. When carrying or transporting a held by means of the holding device, for example sucked workpiece part to a storage location also occur centrifugal forces on the workpiece part, which may not exceed the holding force of the holding elements, for example in the form of suction pads.

To avoid a relative movement of the workpiece part, it is for example off DE102015223062B3 known to hold the workpiece part by means of a holding unit (eg vacuum unit) relative to the skeleton grid in a defined position during lateral displacement. For this purpose, the suckers are placed on the workpiece part to prevent movement of the workpiece part in and / or against the direction of gravity. A stronger fixation of the workpiece part can be done by suction of the workpiece part. Since the holding unit is not allowed to collide with a machining head for cutting the workpiece, the holding unit covers in the method according to FIG DE102015223062B3 usually the workpiece part is not complete.

Out DE19817213A1 It is known to calculate in a vacuum gripper depending on workpiece and process parameters (including material, dimensions, surface texture, transport direction, transport acceleration), whether a single suction pad is sufficient or if several suction pads for safe transport of the workpiece are required or at least advantageous.

In WO2007115633A1 It is proposed to adapt or optimize the acceleration and / or transport speed to the capabilities of a vacuum gripper with a process model stored in the control of a vacuum handling device. For example, it can be determined whether the suction gripper can generate a high holding force, so that a high speed can be driven.

Object of the invention

In contrast, the present invention has the object to provide a method by which a holding position can be found in which by means of a predetermined number and location of holding elements, in particular of suction pads, which act on the workpiece part, a reliable movement of the workpiece part on a Workpiece support and / or a safe carrying or transporting the held, in particular sucked workpiece part is possible. In this way, in spite of acting friction, weight and / or centrifugal force a secure hold of the workpiece part to the holding elements of the holding device can be achieved.

Subject of the invention

This object is achieved by a method of the type mentioned, comprising the steps of: a) setting a holding position of the holding device in which at least one holding element at least partially overlaps with the workpiece part to act on the workpiece part, b) determining one of c) evaluating the holding position as suitable for moving or carrying the workpiece part, if for each effective holding elements a transmittable respectively to the workpiece part to be displaced in a direction of displacement transverse force or a holding and / or transverse force which can be transmitted in each case to the workpiece part to be supported in a transport direction fulfills a weighting criterion dependent on the resultant force.

Depending on the geometry of the workpiece part, the material properties (type of material, thickness, size), the coefficient of friction of the material of the workpiece part on the workpiece support, as well as the position and number of effective holding elements, ie those holding elements, the overlap at least partially with the workpiece part, an evaluation criterion can be determined, which allows a statement about the strength of the fixation of the workpiece part on the holding device.

The basic idea of this method is that the forces acting on the holding device resulting (horizontal and possibly vertical) are distributed to the effective holding elements, taking into account the present geometric relationships. In other words, the forces that act on the holding device, not necessarily equally distributed to all effective holding elements. It is thus used an evaluation criterion that can make a statement for the selected holding position of the holding device and thus for each of the holding elements which act on the workpiece part, whether it is when moving or carrying the workpiece part to a relative movement between the workpiece part Holding device comes. With the aid of the evaluation criterion, a respective holding position of the holding device can therefore be assessed as suitable or unsuitable.

If the evaluation criterion for each individual effective holding element is met, the displacement or the carrying of the workpiece part can be carried out reliably. If the evaluation criterion is not met, i. If the load is too great, it is outputted as evaluation result or found that with the present holding position of the holding device or the holding elements no reliable displacement or no safe carrying of the workpiece part can take place.

In the simplest case, the evaluation criterion may be to check whether the transferable by the effective holding element transverse force or the transferable holding force is at least as large or larger than the resulting force or the proportion of the resultant force in the relevant spatial direction. Preferably, the evaluation criterion for this includes the amount of resultant force applied to the effective holding member multiplied by a safety factor. The evaluation criterion for the holding position of the holding device on the workpiece part, in the case of displacement of the workpiece, requires that the load or the resulting force on each individual holding element F _{res, i} smaller than the transmittable shear force _{Fq, i} against the displacement direction, so that no relative movement between the holding member and the workpiece part is formed, ie, it should apply: F _{Q, i} ≥ SF _{res, i} , where S denotes the safety factor, which is greater than 1, but if necessary also = 1 can be selected. In the case of carrying or transporting the workpiece, the above formula applies mutatis mutandis to the resulting force in the horizontal direction, ie parallel to the plate-shaped workpiece part (against the horizontal component of the transport direction). In addition, the evaluation criterion must also be for the holding force F _{H, i} in the vertical direction, ie, in the vertical direction, the following applies: F _{H, i} ≥ SF _{res, i} .

The evaluation criterion or the evaluation rule can basically be used for all processes in which a decision must be made as to whether the fixation of a (flat) workpiece part, which via a clamping or holding force and / or friction at discrete points (for example, suckers or grippers) must be moved in a spatial direction, can be carried out reliably or not, for example, in the above-described holding or transport of the plate-shaped or flat workpiece part.

For the purposes of this application, carrying the workpiece means lifting the workpiece part in the vertical direction, in which no movement of the workpiece part takes place in the horizontal direction, so that only the force of gravity and an acceleration force acting in the vertical direction act on the workpiece part. The carrying of the workpiece also includes a transport of the workpiece part, in which the workpiece part is not only raised but additionally also in at least one further spatial direction (horizontal) is moved. During transport of the workpiece part act on the workpiece part both in the horizontal direction and in the vertical direction acceleration forces, and in addition to gravity. For simplicity, it is assumed in all subsequent considerations that these forces act or act on the center of gravity of the workpiece part.

If, in step c) of the method according to the invention, the holding position is assessed as unsuitable for the reliable shifting or carrying of the workpiece part, steps a) to c) can be repeated with a changed number of effective holding elements and / or with a changed holding position until the stop position meets the evaluation criterion.

In the former case, for example, in a step d) those effective holding elements for which the evaluation criterion has not been met are neglected, and the calculation of the applied resultant force can be carried out again for the remaining effective holding elements. If the evaluation criterion for all remaining effective holding elements is fulfilled, then the (initial) holding position defined in step a) is evaluated as suitable. If this is not the case, then step d) can be repeated. If, after repeated repetition of step d) if necessary, no effective holding elements remain, the holding position must be changed and then steps b), c) and if necessary d) must be repeated.

The value required for the comparison in step c) for the transverse force or holding force transferable by a holding element, for example by a nipple or gripper, is dependent on the suction, clamping or contact force with respect to the workpiece part and the coefficient of friction between the nipple or gripper and the workpiece part, which depends on the material or on the surface condition of the workpiece part (eg dry or oiled etc.) as well as on the material and the surface condition of the suckers or grippers. The value for the transmittable shear force is either specified in the manufacturer's data sheets of the holding device, for example a vacuum cleaner manufacturer, or can be determined by means of displacement or with the aid of carrying tests. During the displacement of the workpiece part, the action of the holding device can be done by applying or pressing a surface suction or the effective suction or by additional generation of a vacuum. The applicable values for the transmittable shear force of a single nipple in these cases must typically be determined by test series.

In general, the method is completed when a suitable holding position or holding positions for the holding device (s) has been found (s). Optionally, the method may be further performed after finding a suitable holding position, i. E. The steps a) to c) can be repeated with changed holding positions until several process-safe holding positions are found. From the process-safe stop positions, it is then possible to select the one which best or optimally fulfills the evaluation criterion. In the event that two or more holding devices are used to move or carry one and the same workpiece part, the resulting force on a respective holding element of a holding device typically also depends on how many holding elements of the other holding devices act on the workpiece part and where they attack the workpiece part. For the following considerations, it is assumed for the sake of simplicity that only a single holding device is used for displacing or holding the workpiece part.

During the first execution of the method step a), an initial holding position of the holding device can be defined, in which a predetermined number of holding elements of the holding device completely or partially overlap with the workpiece part. A partial overlap is understood to mean that only a partial region of the effective surface of a holding element, for example a suction surface, overlaps the workpiece part. In other words, the edge contour of the workpiece part intersects the effective surface of the holding element.

The initial holding position can be determined by first defining a, in particular rectangular, enclosing contour surrounding the workpiece part to be removed. The initial definition of the holding position preferably takes place uniformly, i. the holding device has equal distances to the edges of the Umschließungskontur. If this is not possible due to collisions between the holding device and other components, for example a machining head, the holding device is designed taking into account a minimum distance to the components, e.g. to the machining head, placed at equal distances to the edges of the enclosing contour. When two or more holding devices are used to move or support one and the same workpiece part, their initial holding positions are typically also set such that the holding devices are arranged uniformly in relation to the enclosing contour, i. the holding devices have equal distances to the edges of the enclosing contour.

In one variant, the resultant force is determined as a vectorial sum of a first force component and a second force component, wherein the first force component results from a total force acting on the center of gravity of the workpiece part to be displaced or supported, and wherein the second force component is one Transverse force on a respective holding element due to a force acting on the center of gravity of all effective holding elements containing portion of the holding device torque results. The resulting force on a holding element is generally composed of the two force components described above. In the event that the center of gravity of the portion of the holding device coincides with the effective holding elements with the center of gravity of the workpiece part, eliminates the second force component, i. this has the value zero.

For the typically present case that the plate-shaped workpiece or the workpiece part cut free from this has a constant thickness and density, the center of gravity of the workpiece part coincides with the centroid of the workpiece part. Accordingly, the center of gravity of the portion of the holding device coincides with the centroid of the portion of the holding device, provided that the weight of the base or suction plate of the holding device is also distributed homogeneously.

In one variant, the first force component of the resulting force is determined by the acting on the center of gravity of the workpiece part to be moved or transferred total force is evenly divided between the effective holding elements. In this case, the first force component results from the total force by dividing the total force by the number of effective holding elements.

In a further development, the total force in the form of a frictional force acting counter to a displacement direction is determined for finding the holding position for moving the workpiece part, which is generated by a weight force of the workpiece part and a contact force of the effective holding elements on the workpiece part. During the displacement of the workpiece part with the holding device placed thereon, friction arises between the workpiece part and the workpiece support. This adhesive frictional force acts opposite to the direction of displacement and is subsequently referred to as a substitute force (combined force) F _R * designated. The frictional force acting counter to the direction of displacement F _R * becomes out of normal force F _N perpendicular to the workpiece support multiplied by the adhesion friction coefficient μ _R determined between the workpiece part and the workpiece support, that is: F _R * = F _N μ _R. The workpiece support can be, for example, support brushes, or the workpiece support can be formed of support brushes, which are for example mounted on strips. In the case where the workpiece rest is formed of casters, the adhesive friction coefficient is replaced by the sliding friction coefficient of the workpiece rest.

The normal force F _N has a first share F _N1 on, which is due to the weight of the workpiece part. The following applies: F _N1 = m _w g, where mw is the mass of the workpiece part and g is the gravitational acceleration ( 9 , 81 m / s ² ). The normal force F _N also has a second share F _N2 on, which is due to the pressure force of the holding elements on the workpiece part. The pressure force F _N2 varies, depending on whether a vacuum is applied to the holding elements, for example in the form of a suction cup or suction gripper, whether the holding device, on which the holding elements are mounted, rests with its own weight on the workpiece part or is additionally pressed onto the workpiece part. If the holding device, for example in the form of a surface vacuum cleaner, rests on the workpiece part with its own weight, then: F _N2 = gm _F n _WS / n _S , where m _F nws designate the number of effective holding elements and ns the total number of holding elements of the holding device. As described above, the frictional force acting against the direction of displacement is distributed F _R * uniformly on all effective holding elements or suckers, ie for a single holding element i is: F _{R, i} = F _R * / n _WS .

In an alternative variant, when the holding position for carrying the workpiece part is found, the total force is determined as the vectorial sum of an acceleration force acting counter to a transport direction in the center of gravity of the workpiece part and a weight force acting on the workpiece part in the center of gravity of the workpiece part. The transport direction is basically arbitrary, but often the workpiece part is first lifted in the vertical direction and subsequently transported or moved in a plane parallel to the workpiece support horizontal plane. It is understood that the transport direction and also the acceleration force can vary over time during the carrying of the workpiece part.

When comparing the resulting force with the evaluation criterion, this circumstance can be taken into account by the fact that a maximum value of the total force occurring during transport or a respective maximum value of a force component of the total force in one of the three spatial directions is included in the resulting force on which the evaluation criterion depends. In principle, the evaluation criterion dependent on the resultant force can not consist of a single value, for example dependent on the magnitude of the resultant force, but two or more force components of the resultant force acting in different spatial directions can form the evaluation criterion. For example, a force component of the total force acting in a space direction in a horizontal direction (or in a horizontal plane) such that the weight force of the workpiece part does not enter therein may be a first force component of the resultant force in a horizontal space direction that is compared to the transmittable shear force. Accordingly, a vertically acting portion of the first force component or the resultant force with the transferable in the vertical direction holding force can be compared. However, it may also be possible to use only the amount of the resulting force (without decomposition into the portions acting in different spatial directions) as the evaluation criterion.

In a further variant, the second force component is determined by means of a torque which is exerted on the center of gravity of the portion containing the effective holding elements when the workpiece part is displaced in a displacement direction or when the workpiece part is carried in a transport direction by the workpiece part. When moving the workpiece part, the torsional or torsional moment acts only horizontally, ie in a plane parallel to Workpiece support or to a plane in which the effective holding elements are arranged. In the event that the workpiece part is carried and transported only in the vertical direction, in addition acts a torsional moment on the center of gravity of the portion, wherein the torsional moment is generated by the weight of the workpiece part. In the event that the transport direction also has a proportion which acts in a horizontal direction, in addition acts a torsional or torsional moment in the horizontal direction.

In a further development, the torque exerted on the center of gravity of the partial region is determined from a frictional force of the workpiece part on the workpiece support and a distance between the center of gravity of the partial area and a center of gravity of the workpiece part perpendicular to the displacement direction when finding the holding position for the displacement of the workpiece part. The torque T _z calculated from the frictional force F _R of the workpiece part multiplied by the distance L _{R, x} perpendicular to the direction of displacement between the (area) center of gravity of the workpiece part and the (area) center of gravity of the portion with the effective holding elements. For the calculation of the friction force F _R Only the weight of the workpiece part is taken into account, since the normal force, which is applied by the holding device or by the effective holding elements, is located in the pivot point or in the center of gravity of the portion. For the friction force: F _R = m _W g μ _B , for the torque follows: T _z = FR * LR, x.

The moment T _z calls on a single holding element a lateral force F _{Tz, i} perpendicular to the distance vector between the holding element and the center of gravity of the subregion with the effective holding elements. The amount of lateral force F _{Tz, i} behaves proportionally to the length of the distance vector. For the case of shifting the workpiece part considered here, the resulting force Fres results on a holding element by a vectorial addition of the first force component in the form of the frictional force F _{R, i} (see above) and the second force component F _Tzi in the form of the transverse force resulting from the torque.

In an alternative variant, which relates to finding the holding position for supporting the workpiece part, the resulting force is compared with the lateral force in the horizontal direction and the holding force in the vertical direction individually. As described above, the non-positive connection between the effective holding elements and the workpiece part must exceed the load or the resultant force on the holding elements, if the workpiece part is not to move relative to the holding device. In order to make a statement about the reliable carrying of the workpiece part, for each holding element, for example, for each sucker, the proportion of the resultant force in the horizontal direction with the transmittable by the sucker, acting in the horizontal direction transverse force and the proportion of the resultant force in the vertical direction compared with the holding force of a respective holding element acting in the vertical direction. Alternatively, a comparison of the resulting force, which has not been broken down into its proportions in different spatial directions, can be made with a vectorial sum of the transmittable shear force and the transmittable holding force of a respective holding element.

In a further variant, with a partial overlapping of effective holding elements with the workpiece part, the transversal force transferable by these holding elements to the workpiece part to be displaced or the holding and / or transverse force transmitted to the workpiece part is reduced by a predetermined factor. The partial area with the effective holding elements may contain both holding elements which rest completely (i.e., with the entire holding or suction surface) on the workpiece part, as well as holding elements with a partial covering. A reduced transmittable transverse force (and carrying capacity or holding force) is assigned to these holding elements, which only partially cover the workpiece part. For example, the value of the transferable to the workpiece part transverse force for the workpiece part only partially covering effective holding elements with a factor less than 1, for example 0.5, are multiplied. Also, the holding force transferable to the workpiece part by a holding element can be reduced by a factor of e.g. 0.5 multiplied.

Another aspect of the invention relates to a computer program product which is designed to carry out all the steps of the method as described above, when the computer program runs on a data processing system. The data processing system can in particular be a programming system, ie a computer for programming the control programs for a numerical control device of a device for moving and / or supporting a workpiece part or a mechanical arrangement with such a device. If the computer program is running in the programming system, a processing program is generated, which includes a sequence of (control) commands for taking a suitable for moving or supporting the workpiece workpiece holding position by the device for moving and / or carrying the Workpiece part has. On the basis of the comparison with the evaluation criterion described above, a placement or arrangement of the holding device is evaluated at a specific stop position and, if necessary, iteratively adjusted until the Evaluation criterion for all effective holding elements is met. The processing program generated in this way can then be carried out by a control device of the device or a mechanical arrangement containing this device.

Further advantages of the invention will become apparent from the description and the drawings. Likewise, the features mentioned above and the features listed further can be used individually or in combination in any combination. The embodiments shown and described are not to be understood as exhaustive enumeration, but rather have exemplary character for the description of the invention.

• 1a eine schematische Darstellung eines Beispiels einer maschinellen Anordnung mit einer Laserschneidmaschine und mit einer Vorrichtung zum Verschieben und zum Tragen eines von einem Restgitter freigetrennten Werkstückteils,
• 1b eine Darstellung einer Halteeinrichtung der Vorrichtung von 1a in Form eines (Vakuum-)Flächensaugers, dessen Halteelemente in Form von Saugern auf dem Werkstückteil und dem Restgitter aufliegen, um das Werkstückteil bei einer Verschiebung relativ zum Restgitter zu fixieren,
• 2a,b Darstellungen einer Saugerplatte des Flächensaugers, die einen Teilbereich aufweist, in dem sich wirksame Sauger mit dem Werkstückteil überschneiden, sowie von einer auf den Schwerpunkt des Teilbereichs wirkenden Gesamt-Kraft bzw. eines auf den Schwerpunkt des Teilbereichs wirkenden Moments,
• 3 eine Darstellung des Teilbereichs der Saugerplatte des Flächensaugers mit den wirksamen Saugern sowie der resultierenden Kraft auf einen der wirksamen Sauger, die eine vektorielle Summe einer ersten und zweiten Kraftkomponente bildet,
• 4 eine Darstellung der maschinellen Anordnung von 1a, bei welcher das entlang der Werkstückauflage verschobene Werkstückteil mit Hilfe von zwei Flächensaugern angehoben und transportiert wird, sowie
• 5a,b Darstellungen des Werkstückteils und eines Flächensaugers von 4 in einer Draufsicht und einer Seitenansicht mit den auf den Schwerpunkt des Werkstückteils wirkenden Kräften sowie mit den auf den Schwerpunkt eines Teilbereichs des Flächensaugers wirkenden (Torsions-)Momenten.

Show it:

• 1a a schematic representation of an example of a mechanical arrangement with a laser cutting machine and with a device for moving and supporting a freed from a skeleton workpiece part,
• 1b a representation of a holding device of the device of 1a in the form of a (vacuum) surface vacuum, the holding elements rest in the form of suckers on the workpiece part and the skeleton grid to fix the workpiece part in a shift relative to the skeleton grid,
• 2a, b Illustrations of a suction plate of the surface vacuum cleaner, which has a partial region in which effective suckers overlap with the workpiece part, and of a total force acting on the center of gravity of the partial region or of a moment acting on the center of gravity of the partial region,
• 3 a representation of the portion of the suction plate of the surface sucker with the effective suckers and the resulting force on one of the effective sucker, which forms a vectorial sum of a first and second force component,
• 4 a representation of the mechanical arrangement of 1a in which the workpiece part displaced along the workpiece support is lifted and transported by means of two surface vacuums, as well as
• 5a, b Representations of the workpiece part and a surface suction of 4 in a plan view and a side view with the forces acting on the center of gravity of the workpiece part and with the forces acting on the center of gravity of a portion of the surface suction (Torsions-) moments.

In the following description of the drawings, identical reference numerals are used for identical or functionally identical components.

1a shows a machine arrangement 1 that a laser cutting machine 2 and a device for displacing and supporting a workpiece part comprising an unloading station 3 the laser cutting machine 2 forms. Alternatively, the mechanical arrangement 1 also as mechanical separating device, eg punching machine, as punching laser combination machine, as plasma cutting machine, water jet cutting machine or similar. be executed. The laser cutting machine shown here by way of example 2 has a non-illustrated guide structure with a portal cross member 4 along which there is a movement unit 5 with a laser cutting head 6 perpendicular to the plane of 1a procedure, ie in X Direction of a XYZ Coordinate system. In addition, the laser cutting head 6 relative to the portal cross member 4 Movements in the vertical direction ( Z Direction).

The portal crossbeam 4 spans a workpiece support 7 , which is occupied at its top in a conventional manner with brushes. The workpiece support 7 includes a machining side support table 8th and a discharge-side support table aligned therewith in the horizontal direction 9 , The machining side support table 8th and the discharge side support table 9 are by a pad gap 10 Separate (gap) in which a suction device is located and / or one or more workpiece support slide 11 in X Direction can be arranged to be movable perpendicular to the plane of the drawing.

On the machining side support table 8th is an in X Direction, ie perpendicular to the plane, extending crossbar 12 by means of a movement device indicated by a double arrow 13 in positive and in negative Y Direction guided by a motor. The crossbar 12 is with several in the longitudinal direction of the cross rail 12 mutually offset clamping claws 14 Provided. The clamps 14 hold a plate-like workpiece 15 before and during the cutting process by means of the laser cutting head 6 , wherein the cutting machining of the workpiece 15 in a working area of the laser cutting machine 2 between the two support tables 8th . 9 he follows. Like this in 1b is shown holding the clamps 14 after machining the workpiece 15 and the associated removal of a workpiece part created as a workpiece cutout 16 a while processing the workpiece 15 in addition to the workpiece part 16 produced and as a skeleton 17 present residual workpiece.

The unloading station 3 includes a frame eighteen on which a horizontal beam 19 is stored raised and lowered. cantilevers 20 , which are perpendicular to the plane of the drawing, are along the horizontal support 19 traversable. The cantilevers 20 store a guide rail 21 during movements of the guide rail 21 perpendicular to the drawing plane, ie in X -Direction. Along the guide rail 21 can have three fixtures 22 . 23 . 24 by means of a movement device indicated by a double arrow 25 in positive and negative Y Direction over the workpiece support 7 to be moved.

The first holding device 22 has a first holding device in the form of a first surface suction 26 on. Accordingly, the second holding device also has 23 a second holding device in the form of a second surface suction 27 and the third holding device 24 has a third holding device in the form of a third surface suction 28 on. The three holding devices or the surface suction cups 26 . 27 . 28 are identical and can with the help of acting as actuators pneumatic piston-cylinder units 29 . 30 . 31 moved in the vertical direction (Z direction) and delivered.

The in 1b illustrated first surface vacuum 26 has a housing 32 with a suction plate 33 on, which is provided with a plurality of holes not illustrated. The holes are used to hold suckers 34 each of which has a bellows-like folded sucker sleeve 35 having. The sucker sleeves 35 stand at the in 1b illustrated initial state of the surface suction 26 opposite the suction plate 33 of the housing 32 in front and are perpendicular to the suction plate 33 elastically deformable. The suckers 34 can be designed as active or passive vacuum cleaner. A suction chamber inside each sucker sleeve 35 can be switched to a vacuum generator, not shown, so that the vacuum generator via the suction chambers of the sucker 34 Suck in air and either on all suckers 34 simultaneously or controlled on selected suckers can generate a vacuum or a negative pressure to the workpiece part 16 or the skeleton grid 17 to suck.

An in 1a schematically illustrated programmable numerical control device 40 controls all essential functions both on the laser cutting machine 2 as well as at the unloading station 3 the machine arrangement 1 , From the numerical control device 40 In particular, the motor drive acting as workpiece drive and as residual workpiece drive is controlled 13 for the cross rail 12 at the laser cutting machine 2 who in 1a indicated by a double arrow, as well as in 1a also indicated by a double arrow motorized movement device 25 for the three holders 22 . 23 . 24 , In addition to the workpiece drive 13 and the movement device 25 for the three holders 22 . 23 . 24 are among other things for the sake of clarity, not shown further motor drives provided by means of which the lifting movements of the horizontal support 19 as well as the horizontal movements of the cantilevers 20 and the guide rail 21 are executed and their control also the numerical control device 40 the machine arrangement 1 is being used. Other than described above, the numerical control device 40 a part of the unloading station 3 form or it can for the numerical control of the laser cutting machine 2 and the unloading station 3 two separate numerical control devices may be provided. The control programs for the programmable numerical control device 40 are usually generated using a programming system that runs on a separate computer. By means of the programming system, the orientation of the workpiece parts 16 within the workpiece 15 (Nesting), the machining parameters for the cutting machining and the positioning of other machine components such as the holding devices 22 . 23 . 24 set during and after processing.

In the presentation of 1b has the laser cutting head 6 in the work area, between the two support tables 8th . 9 the workpiece support 7 is formed, carried out the final separation cut and thereby from the in 1a shown workpiece 15 this in 1b shown workpiece part 16 separated and in addition as residual workpiece the skeleton 17 generated. The horizontal carrier 19 got on the frame eighteen the unloading station 3 moved so far down that one or more of the extended piston rods of the pneumatic piston-cylinder units 29 . 30 . 31 attached holding devices in the form of surface suction 26 . 27 . 28 More specifically, the sucker sleeves 35 the sucker 34 , with its underside at the top of the workpiece part 16 issue.

Based on the conditions according to 1b is from the controller 40 the movement device 25 for moving the holding devices 22 . 23 . 24 activated to the workpiece part 16 by means of one or more of the surface suckers 26 . 27 . 28 from the cutting area of the laser cutting machine 2 to the side in the direction of the discharge side support table 9 to move and possibly subsequently upwards from the discharge side support table 9 refer to. The number of surface vacuums used for moving 26 . 27 . 28 depends on the size and shape of the workpiece part 16 , If the workpiece part 16 unlike in 1b shown by the skeleton 17 surround is, the skeleton can 17 parallel to the movement of the surface vacuum 26 . 27 . 28 with the help of the cross rail 12 and the movement device 13 be moved to the side. Relative movements between the skeleton 17 and the workpiece part 16 as well as relative movements between the workpiece part 16 and the surface suckers 26 . 27 . 28 should be avoided as completely as possible.

To achieve this, transfers in the example shown, the first surface vacuum 26 with those suckers 34 , The suction surfaces are at least partially with the workpiece part 16 overlap (hereinafter referred to as effective suckers 34a referred to), in the direction of displacement Y acting lateral force _{FQ, i} on the workpiece part 16 , as described below by means of 2a, b as well as by 3 will be described in more detail. In 2a, b was simplified to the representation of the residual grid 17 as well as on the representation of the second surface vacuum 27 waived. In addition, for the sake of simplification of the following calculations, the presence of the second surface vacuum was made 27 not considered, ie it was assumed that only the first surface vacuum 26 Forces on the workpiece part 16 transfers and from the workpiece part 16 Absorbs forces.

Those of the effective suckers 34a of the first surface vacuum 26 in the direction of displacement Y on the workpiece part 16 transmittable shear force _{FQ, i} (see. 3 ) is effective for all suckers 34 of the first surface vacuum 26 same size. The transmittable shear force _{FQ, i} an effective nipple 34a depends on the contact pressure of the effective vacuum cleaner 34a or the first surface vacuum 26 on the workpiece part 16 and the coefficient of friction between the respective effective sucker 34a and the workpiece part 16 , among other things, the surface texture of the workpiece part 16 is dependent. The effect of the first surface vacuum 26 or the individual effective sucker 34a can by laying or pressing the surface suction 26 or by additionally generating a vacuum by means of the vacuum generator of the surface vacuum cleaner 26 respectively. The applicable values for the transmittable shear force in these cases _{FQ, i} a respective effective sucker 34a are typically determined in advance empirically by series of experiments, ie the transmittable shear force _{FQ, i} is known in advance.

To achieve that the workpiece part 16 during the displacement along the workpiece support 7 not relative to the skeletal grid 17 It is necessary, in the programming system in the generation of the control program for the control device 40 a stop position HP of the first surface vacuum 26 relative to the workpiece part 16 find, in which for every single effective sucker 34a the transmittable shear force _{FQ, i} meets an evaluation criterion. Under a holding position HP of the first surface vacuum 26 becomes a position relative to the workpiece part 16 understood, in which at least one of the suckers 34a More precisely, at least one suction surface, at least partially with the workpiece part 16 overlaps.

At the in 2a, b shown holding position HP a number of nws of twelve effective suckers overlap 34a with their respective circular suction surfaces completely with the workpiece part 16 , An in 2a, b by a dashed border limited, rectangular portion 36 of the first surface vacuum 26 , more specifically, the sucker plate 33 , contains all effective suckers 34a , in the example shown on the sucker plate 33 are arranged uniformly distributed. The width B of the subarea 36 corresponds to the width of the suction plate 33 and the length L of the subarea 36 corresponds to one in 1b illustrated overlap length L , along which the first surface sucker 26 with the workpiece part 16 overlaps.

wobei S einen Sicherheitsfaktor (>1) und i den i-ten Sauger 34a bezeichnet (i = 1, ... nws). Erfüllt die Halteposition HP das obige Bewertungskriterium, so kann das Werkstückteil 16 auf der Werkstückauflage 7 prozesssicher verschoben werden, ohne dass es zu einer unerwünschten Bewegung des Werkstückteils 16 relativ zum Restgitter 17 kommt.In the following considerations, an evaluation criterion is used in which that of a respective sucker 34a in the direction of displacement Y on the workpiece part 16 transmittable shear force _{FQ, i} with one on a respective sucker 34a against the direction of displacement Y acting resulting force F _{res, i, y} is compared, ie it is checked whether for all twelve effective suckers 34a applies: $${\text{F}}_{\text{Q}.\text{i}}\ge {\text{S F}}_{\text{res}.\text{i}.\text{y}}.$$

where S is a safety factor (> 1) and i is the i-th sucker 34a denotes (i = 1, ... nws). Meets the stop position HP the above evaluation criterion, so the workpiece part 16 on the workpiece support 7 be moved reliably, without causing unwanted movement of the workpiece part 16 relative to the skeleton 17 comes.

For the determination of against the direction of displacement Y effective share F _{res, i, y} in the displacement of the workpiece part 16 on a respective sucker 34a exerted resulting force F _{res, i} First, the resulting force F _{res, i} on a respective effective sucker 34a certainly. The resulting force F _{res, i} is the vectorial sum of a first force component F _{R, i} and a second force component F _{Tz, i} together:

wobei F_N die in 1b dargestellte Normalkraft auf das Werkstückteil 16, vereinfacht auf den Schwerpunkt Sw des Werkstückteils 16, und µ_B den Reibungskoeffizienten zwischen dem Werkstückteil 16 und den Auflagebürsten der Werkstückauflage 7 bezeichnen. Die Normalkraft F_N variiert, je nachdem ob an den Saugern 34a ein Vakuum anliegt, ob der erste Flächensauger 26 mit seinem Eigengewicht aufliegt oder auf das Werkstückteil 16 gedrückt wird.The first force component F _{R, i} results from a (simplified considered) on the center of gravity Sw of the workpiece part 16 acting total force F _R * (here: frictional force), which in the example shown counter to the direction of displacement Y acts and on the static friction between the workpiece part 16 and the Pad brushes of the workpiece support 7 is due. For the friction force F _R * on the focus sw of the workpiece part 16 applies: $${\text{F}}_{\text{R}}{}^{*}={\text{F}}_{\text{N}}{\mu }_{\text{B}}.$$

in which F _N in the 1b illustrated normal force on the workpiece part 16 , simplified to the center of gravity Sw of the workpiece part 16 , and μ _{B is} the coefficient of friction between the workpiece part 16 and the support brushes of the workpiece support 7 describe. The normal force F _N varies, depending on whether at the suckers 34a a vacuum is applied, whether the first surface vacuum 26 rests with its own weight or on the workpiece part 16 is pressed.

wobei m_w die Masse des Werkstückteils 16, m_F das Eigengewicht des Flächensaugers 26, g die Schwerebeschleunigung (9,81 m/s²) und ns die Gesamtzahl der Sauger 34 des ersten Flächensaugers 26 (im gezeigten Beispiel ns = 44) bezeichnen.Below it is assumed that the first surface sucker 26 rests with its own weight. In this case applies to the frictional force F _R * : $${\text{F}}_{\text{R}}{}^{*}=\left({\text{m}}_{\text{W}}+{\text{m}}_{\text{F}}*\left({\text{n}}_{\text{WS}}/{\text{n}}_{\text{S}}\right)\right)*\text{G}*{\mu }_{\text{B}},$$

in which m _w the mass of the workpiece part 16 . m _F the weight of the vacuum cleaner 26 , g the gravitational acceleration (9,81 m / s ² ) and ns the total number of suckers 34 of the first surface vacuum 26 (ns = 44 in the example shown).

The opposite to the direction of displacement Y acting friction force F _R * spreads evenly on all effective suckers 34a ie for the ith effective sucker 34a (see. 3 ) applies: $${\text{F}}_{\text{R}\text{i}}={\text{F}}_{\text{R}}*/{\text{n}}_{\text{WS}}\left({\text{here: n}}_{\text{WS}}=12\right),$$

The second force component F _{Tz, i} that is on an effective sucker 34a acts, results from one on the center of gravity ss of the subarea 36 with the effective suckers 34a acting moment T _z (see. 2 B) that of the workpiece part 16 during the displacement along the direction of displacement Y is produced. The moment T _z calculated from the frictional force F _R of the workpiece part 16 multiplied by the distance L _{R, x} between the (area) center of gravity Sw of the workpiece part 16 and the (area) center of gravity ss of the subarea 36 with the effective suckers 34a in X Direction, ie perpendicular to the direction of displacement Y , For the calculation of the normal force F _N that is in the frictional force F _R enters, in this case, only the weight of the workpiece part 16 taken into account as the proportion of normal force passing through the first surface sucker 26 is introduced, is in the fulcrum, ie it applies: $${\text{F}}_{\text{R}}={\text{m}}_{\text{W}}\text{G}{\mu }_{\text{B}}{\text{and T.}}_{\text{z}}={\text{F}}_{\text{R}}*{\text{L}}_{\text{R}\text{, x}},$$

wobei r_i den Betrag des Abstandsvektors ${\overrightarrow{r}}_l$

zwischen dem Schwerpunkt Ss des Teilbereichs 36 der Saugerplatte 33 und der Position des hier betrachteten, i-ten wirksamen Saugers 34a, sowie r_i,x die X-Komponente und r_i,y die Y-Komponente des Abstandsvektors ${\overrightarrow{r}}_l$

bezeichnen.For the moment T _z to the center of gravity Ss of the subarea 36 resulting power F _{Tz, i} on the i-th effective sucker 34a applies: $$F_{Tz.i}=\frac{T_z*r_i}{{\displaystyle {\Sigma }_{i=1}^{n_{WS}}{r}_i^2}}=\frac{F_R*L_{R.x}*\sqrt{\left(r_{i.x}^2+r_{i.y}^2\right)}}{{\displaystyle {\Sigma }_{i=1}^{n_{W\mathrm{<figure-callout\; id="2"\; label="S\; r\; i"\; filenames="DE102018203061A1\_0023.png,DE102018203061A1\_0025.png"\; state="\{\{state\}\}">S\; </figure-callout>}}}{r}_i^{}{}_2^{}}}.$$

where r _{i is} the magnitude of the distance vector ${\overrightarrow{r}}_l$

between the center of gravity Ss of the subarea 36 the suction plate 33 and the position of the i-th effective nipple considered here 34a , such as r _{i, x} the X Component and r _{i, y} the Y Component of the distance vector ${\overrightarrow{r}}_l$

describe.

$$F_{res,i,y}=F_{R,i}+F_{Tz,i}\ast \frac{r_{i,x}}{r_i}=\frac{F_R^{\ast }}{n_{WS}}+\frac{F_R\ast L_{R,x}\ast r_{i,x}}{{\displaystyle {\sum }_{i=1}^{n_{WS}}{r}_i^2}},$$

wobei F_res,i den Betrag der resultierenden Kraft $\overrightarrow{F_{res,l}}$

bezeichnet, d.h. $$F_{res,i}=\sqrt{F_{res,i,x}^2+F_{res,i,y}^2}.$$

For those from the first force component F _{R, i} and from the second force component F _{Tz, i} resulting power F _{res, i} more precisely for theirs X -Component F _{res, i, x} or for their Y -Component F _{res, i, y} applies: $$F_{res.i.x}=-F_{Tz.i}*\frac{r_{i.y}}{r_i}=\frac{F_R*L_{R.x}*r_{i.y}}{{\displaystyle {\Sigma }_{i=1}^{n_{W\mathrm{<figure-callout\; id="2"\; label="S\; r\; i"\; filenames="DE102018203061A1\_0023.png,DE102018203061A1\_0025.png"\; state="\{\{state\}\}">S\; </figure-callout>}}}{r}_i^{}{}_2^{}}}.$$

$$F_{res.i.y}=F_{R.i}+F_{Tz.i}*\frac{r_{i.x}}{r_i}=\frac{F_R^{*}}{n_{WS}}+\frac{F_R*L_{R.x}*r_{i.x}}{{\displaystyle {\Sigma }_{i=1}^{n_{W\mathrm{<figure-callout\; id="2"\; label="S\; r\; i"\; filenames="DE102018203061A1\_0023.png,DE102018203061A1\_0025.png"\; state="\{\{state\}\}">S\; </figure-callout>}}}{r}_i^{}{}_2^{}}}.$$

in which F _{res, i} the amount of the resulting force $\overrightarrow{F_{res.l}}$

designated, ie $$F_{res.i}=\sqrt{F_{res.i.x}^2+F_{res.i.y}^2},$$

für den Vergleich herangezogen wird.As described above, for comparison with the transmittable shear force _{FQ, i} in the present case, where the shift in Y Direction takes place Y -Component F _{res, i, y} the resulting force F _{res, i} with the transmittable shear force _{FQ, i} compared. It is understood that when shifting along a shift direction that is not in Y Direction runs, according to the above procedure of acting counter to the direction of displacement proportion of the resultant force $\overrightarrow{F_{res.l}}$

is used for the comparison.

At the in 2a, b and 3 described example, the condition F _{Q, i} ≥ S F _{res, i, y} for all effective suckers 34a fulfilled, ie the (initial) holding position HP is considered as for moving the workpiece part 16 suitably rated. Will be a suitable stop position in the evaluation performed in the manner described above HP found, this is stored in the instruction set for numerical control. During the Machining of the workpiece part 16 or after its free cut controls the numerical control unit 40 the movement device 13 on, the first surface vacuum cleaner 26 to the in 2a, b shown holding position HP relative to the workpiece part 16 to move and this with the effective suckers 34a on the workpiece part 16 sit up to the workpiece part 16 along the workpiece support 7 to move.

In the event that not all effective suckers 34a in which is with the workpiece part 16 overlapping subarea 36 of the first surface vacuum 26 at the (initial) stop position HP meet the evaluation criterion, the evaluation of the holding position HP be repeated by calculating the effective suckers 34a transmitted forces those suckers 34a for which the evaluation criterion was not met in the first step. Under these changed (tightened) conditions, the evaluation criterion for all remaining effective suckers 34a fulfilled, then the stop position HP rated as suitable.

Can no suitable holding position can be found in this way, so in the programming system, the holding position HP of the surface suction 26 relative to the workpiece part 16 changed. For example, this may be the number of effective suckers 34a or the overlapping subarea 36 be enlarged. Also, it can be tried while maintaining the number of effective suckers 34a by a change in the positioning of the surface vacuum 26 relative to the workpiece part 16 to achieve that the evaluation criterion is met.

In all these cases, a stop position suitable for shifting becomes HP determined iteratively, ie the holding position used for the comparison with the evaluation criterion HP is changed until a suitable stop position HP is found or until a termination criterion is reached. In the simplest case, the termination criterion corresponds to a predetermined number of iterations. In the event that no suitable stop position HP a warning message may be issued indicating that there may be an increased risk of tilting during the shift. Alternatively, in the programming system, the orientation of the workpiece part 16 within the workpiece 15 to be changed. When the holding devices 22 . 23 . 24 are designed with variably positionable suction pads instead of a surface suction, a change in the suction arrangement is possible.

The method described above for finding a suitable holding position HP can be analogously applied to the case that the workpiece part 16 not along the workpiece support 7 is moved, but with the help of the first surface sucker 26 is carried or transported without the workpiece part 16 in this case by the workpiece support 7 is supported. Such a transport of the workpiece part 3 can also with the help of the unloading station 3 the machine arrangement 1 be carried out as described below by means of 4 is shown. After removal of the workpiece part 16 From the discharge side up table is this of one or more surface vacuum, in the example shown by the first and second surface suction 26 . 27 , held. To simplify the calculations, as in the case described above, consider an example below in which the workpiece part only from the first surface suction 26 is held.

For the first surface vacuum 26 arise in the 5b shown relationships. At the in 5b shown holding position HP of the surface sucker 26 are all suckers 34 effective, ie they overlap with the workpiece part 16 , The subarea 36 with the effective suckers 34a thus corresponds to the entire surface of the suction plate 33 , Will the workpiece part 16 of several surface vacuums 26 . 27 . 28 held, so form the effective suckers 34a the surface vacuum 26 . 27 . 28 together the subarea 36 ,

When holding or transporting the workpiece part 16 in the vertical direction Z act on the center of gravity Sw of the workpiece part 16 and thus to the center of gravity Ss of the suction plate 33 the weight F _G = m _w g and possibly an acceleration force in the Z direction F _Z = ± a _z m _W. The total force F _R * in the Z-direction during the movement of the workpiece part 16 is thus F _R * = F _G + F _Z. As described above, the total force F _R * is uniform on the effective sucker 34a divided, ie it applies to the i-th sucker: $${\text{F}}_{\text{R}\text{, for}\text{i}}={\text{F}}_{\text{R}}{}^{*}/{\text{n}}_{\text{WS}}\left({\text{here: n}}_{\text{WS}}=\mathrm{8th}\right),$$

zwischen dem Schwerpunkt Ss der Saugerplatte 33 und der Position des i-ten wirksamen Saugers 34a abhängig.In addition to the total force F _R * affects the focus ss the suction plate 33 also a moment T _{g, z} , which analogously to the case described above to a in Z Direction acting (transverse) force F _{g, z, i} on the i-th effective sucker 34a leads. The power F _{g, z, i} is analogous to the case of the distance vector described above ${\overrightarrow{r}}_l$

between the center of gravity Ss of the sucker plate 33 and the position of the ith effective nipple 34a dependent.

The Z Component of the resulting force F _{res, i, z} is composed of the two force components described above, ie: F _{res, i, z} = F _{R, i, z} + F _{g, i, z} . For the secure holding of the workpiece part 16 on the surface vacuum 26 must the holding power F _{H, i} of the i-th teat 34a fulfill the following condition: $${\text{F}}_{\text{H}\text{i}}\ge {\text{S F}}_{\text{res}\text{i}\text{such}},$$

In the event that the workpiece part 16 additionally along a transport direction in the horizontal direction, ie in one of the X - direction and the Y Direction-containing plane parallel to the workpiece support 7 moved or transported, the above apply to the Z Direction specified equations continue. In addition, a resulting force acts F _{res, i, xy} in the plane parallel to the workpiece support, consisting of an in X Direction acting share F _{res, i, x} and one in Y Direction acting share F _{res, i, y} composed. The resulting force force F _{res, i, xy} in the horizontal direction becomes analogous to the resulting force F _{res, i} determined in the Z direction, ie, the equations given above can be applied analogously, only the weight F _G is not taken into account, as these are perpendicular to XY Level works.

$${\text{F}}_{\text{R}\text{,y}\text{,i}}=\pm {\text{a}}_{\text{y}}{\text{ m}}_{\text{W}}/{\text{n}}_{\text{WS}}.$$

For the in 5a described ratios thus applies to the proportion of the first force component in X Direction or in Y -Direction: $${\text{F}}_{\text{R}\text{, x}\text{i}}=\pm {\text{a}}_{\text{x}}{\text{m}}_{\text{W}}/{\text{n}}_{\text{WS}}\text{or},$$

$${\text{F}}_{\text{R}\text{, y}\text{i}}=\pm {\text{a}}_{\text{y}}{\text{m}}_{\text{W}}/{\text{n}}_{\text{WS}},$$

$${\text{F}}_{\text{res}\text{,i}\text{,y}}={\text{F}}_{\text{R}\text{,i}\text{,y}}+{\text{F}}_{\text{T}\text{,y}\text{,i}}$$

Accordingly, a moment leads T _x or. T _y on the center of gravity Ss of the suction plate 33 analogous to the case described above to a in X Direction or in Y Direction acting (transverse) force F _{Tx, i} or. F _{Ty, i} on the i-th sucker 34a , The two parts F _{res, i, x} or. F _{res, i, y} the resulting force F _{res, i, xy} in X - or in Y Direction in the plane parallel to the workpiece support 7 are composed of the two force components, ie it applies: $${\text{F}}_{\text{res}\text{i}\text{, x}}={\text{F}}_{\text{R}\text{i}\text{, x}}+{\text{F}}_{\text{Tx}\text{i}}\text{or},$$

$${\text{F}}_{\text{res}\text{i}\text{, y}}={\text{F}}_{\text{R}\text{i}\text{, y}}+{\text{F}}_{\text{T}\text{, y}\text{i}}$$

For comparison with that in the horizontal direction or in the ( XY -) level on a single sucker 34a transmittable shear force _{FQ, i} will typically be the amount of resultant force _{Fres, xy, i} determined, for which applies: $$F_{res.i.xy}=\sqrt{F_{res.i.x}^2+F_{res.i.y}^2},$$

For the evaluation criterion applies analogously to the case of shifting described above, that the amount of lateral force _{FQ, i} on a respective sucker 34a the amount of the resulting force F _{res, i, xy} must exceed, being typically a safety factor S is taken into account, ie: $${\text{F}}_{\text{Q}\text{i}}\ge {\text{S F}}_{\text{res}\text{i}\text{, xy}},$$

As described above, the stop position becomes HP as suitable for carrying or for transporting the workpiece part 16 rated if the evaluation criteria for holding power F _{H, i} as well as for the lateral force _{FQ, i} for all effective suckers 34a is satisfied. Because the acceleration forces a _x . a _y . a _z during transport of the workpiece part 16 if necessary change over time, the maximum values of the acceleration that occur during transport can be used for the comparison a _{x, max} . _{ay, max} . a _{z, max} be used.

In the method described above, the number and arrangement of the suckers 34 on the suction plate 33 basically arbitrary. As a rule, however, a larger number of suckers 34 used as shown in the figures. For example, a sucker plate may have a number of 42 x 11 (passive) suckers 34. The diameter of the teat area of a respective teat 34 may for example be in the order of about 10 mm. Depending on the geometry of the workpiece part 16 may not be guaranteed that all effective suckers 34 with their (usually round) teat surfaces completely with the workpiece part 16 overlap.

As in 5a can be seen, the two right outer teat overlap 34a the suction plate 36 only partially with the workpiece part 16 , Accordingly, the two suckers 34a not the entire lateral force _{FQ, i} or the entire holding force F _{H, i} on the workpiece part 16 transferred, as with a complete overlap of the suckers 34a with the workpiece part 16 the case would be. To take this circumstance into account, the value of the two outer suckers 34a on the workpiece part 16 transmittable shear force _{FQ, i} or holding force F _{H, i} multiplied by a factor f (<1) for the comparison with the evaluation criterion, for example with a factor f = 0.5. Because the evaluation criterion for all effective suckers 34a must be met, the use of only partially overlapping effective suckers aggravates 34a the requirements for finding a suitable holding position HP ,

The evaluation rule described above can basically be used for all processes in which it must be decided whether the fixation of a (planar) part, for example a workpiece part, via a holding force and / or friction at discrete points or positions (here: sucker 34 ) in a Space direction must be moved, can be done reliably or not.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102015223062 B3 [0003]
• DE 19817213 A1 [0004]
• WO 2007115633 A1 [0005]

Claims (13)

Method for finding at least one suitable holding position (HP) for at least one holding device (26, 27, 28) which has a plurality of holding elements (34) relative to a holding device (26, 27, 28) on a workpiece support (7 ) to be displaced or a workpiece part (16) to be supported by means of the holding device (26, 27, 28), comprising: a) fixing a holding position (HP) of the holding device (26, 27, 28) in which at least one holding element (34 ) at least partially intersects with the workpiece part (16) to act as an effective holding member (34a) on the workpiece part (16), b) determining one of the workpiece part (16) when displaced or carried on a respective effective holding member (34a) exerted resulting force (F _{res, i;} F _{res, i, z,} F _{res, i, x, y),} c) evaluating the holding position (HP) to be suitable for moving or wearing of the workpiece part (16) when effective for all Holding elements (34 a) a in each case by the effective holding element (34a) on the workpiece part to be displaced (16) in the displacement direction (Y) transmittable transverse force F _{Q, i} or each on the workpiece to be supported part (16) in a transport direction (Z, X, Y) transferable holding force F. _{H, i} and / or lateral force F _{Q, i} a of the resultant force (F _{res, i} ; F _{res, i, z} , F _{res, i, xy} ). Method according to Claim 1 in which the evaluation criterion is determined by the magnitude of the resulting force F _{res, i, y} ; F _{res, i, z} ; F _{res, i, xy} against the direction of displacement (Y) or against the transport direction (Z, X, Y) multiplied by a safety factor S is formed and is satisfied, if: F _{Q, i} ≥ SF _{res, i, y} and / or F _{H, i} ≥ SF _{res, i, z} and / or F _{Q, i} ≥ SF _{res, i, xy} , where S ≥ 1. Method according to Claim 1 or 2 in which, in the event that in step c) the holding position (HP) is judged to be unsuitable for displacing or supporting the workpiece part (16), steps a) to c) continue with an altered number of effective holding elements (34a) and / or repeated holding position (HP) until the predetermined stop position (HP) meets the evaluation criterion. Method according to one of the preceding claims, in which the resultant force (F _{res, i} ; F _{res, i, z} , F _{res, i, x y} ) is expressed as a vectorial sum of a first force component (F _{R, i} ; F _{R, i , z} , F _{R, i, x} , F _{R, i, Y} ) and a second force component (F _{Tz, i} ; F _{Tx, i} , F _{Ty, i} ) is determined, the first force component (F _{R, i} ; F _{R, i, z} , F _{R, i, x} , F _{R, i, y} ) results from a total force (F _R *) acting on the center of gravity (Sw) of the workpiece part (16) to be displaced or supported, and wherein the second force component (F _{Tz, i} ; F _{Tx, i} , F _{Ty, i} ) is a lateral force (F _{Tz, i} ) on a respective effective holding element (34a) which due to a center of gravity (Ss) of one effective holding elements (34a) containing portion (36) of the holding device (26, 27, 28) acting torque (T _Z , T _{g, z} , T _X , T _y ) results. Method according to Claim 4 in which the first force component (F _{R, i} ) of the resultant force (F _{res, i} ) is determined by the total force acting on the center of gravity (Ss) of the workpiece part (16) to be displaced or carried (F _R * ) is evenly divided on the effective holding elements (34 a). Method according to Claim 4 or 5 in which, for locating the holding position (HP) for displacing the workpiece part (16), the total force (F _R *) is determined in the form of a frictional force acting counter to a displacement direction (Y), which is determined by a weight force (gm _w ) of the Workpiece part (16) on the workpiece support (7) and a compressive force (gm _F n _WS / n _S )) of the effective holding elements (34 a) on the workpiece part (16) is generated. Method according to Claim 4 or 5 in which, for finding the holding position (HP) for supporting the workpiece part (16), the total force (F _R *) is calculated as the vectorial sum of an acceleration force (m _w a _Z ; m _w a _x ; m _w a _y ) in the center of gravity (S _W ) of the workpiece part (16) and a counter to a transport direction (Z) on the workpiece part (16) acting weight force (mw g) in the center of gravity (Sw) of the workpiece part (16 ) is determined. Method according to one of Claims 4 to 7 in which the second force component (F _{Tz, i} ; F _{Tx, i} , F _{Ty, i} ) is determined on the basis of a torque (T _Z , T _{g, z} , T _X , T _y ) which is determined when the workpiece part (16 ) in a direction of displacement (Y) or during transport of the workpiece part (16) in a transport direction (Z, X, Y) of the workpiece part (16) on the center of gravity (Ss) of the effective holding elements (34a) containing portion (36) exerted becomes. Method according to Claim 8 in which, for locating the holding position (HP) for displacing the workpiece part (16), the torque (Tz) exerted on the center of gravity (Ss) of the subregion (36) consists of a frictional force (F _R ) of the workpiece part (16) on the workpiece support (7) and a distance (L _{R, x} , L _z , L _x , L _y ) between the center of gravity (S _S ) of the portion (36) and a center of gravity (S _W ) of the workpiece part (16) along the displacement direction (Y ; Z, X, Y) is determined. Method according to Claim 8 in which, for finding the holding position (HP) for carrying the workpiece part (16), the torque (T _{g, z} ) exerted on the center of gravity (S _S ) of the subregion (36) T _X , T _y ) from the total force acting on the center of gravity (Sw) of the workpiece part (16) to be supported (F _R ) and a distance (L _z , L _x , L _Y ) between the center of gravity (S _W ) of to be supported workpiece part (16) and the center of gravity (S _S ) of the portion (36) is determined. Method according to one of the preceding claims, wherein for finding the holding position (HP) for supporting the workpiece part (16) the comparison of the resulting force (F _{res, i} ; F _{res, i, xy} , F _{res, i, z} ) with the transverse force (F _{Q, i} ) in the horizontal direction (X, Y) and the comparison of the resulting force (F _{res, i, xy} , F _{res, i, z} ) with the holding force (F _{H, i} ) in the vertical direction ( Z) individually. Method according to one of the preceding claims, wherein at a partial overlap of effective holding elements (34a) with the workpiece part (16) by the effective holding elements (34a) on the workpiece to be displaced part (16) transferable transverse force (F _{Q, i} ) or on the workpiece to be transported workpiece (16) transferable holding and / or transverse force (F _{H, i} , F _{Q, i} ) is reduced by a predetermined factor. Computer program product, which is designed to carry out all steps of the method according to one of the preceding claims, when the computer program runs on a data processing system.

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