Motion Planning for a Conveyor System of a Servo Press Installation

Abstract

A method for motion planning for a conveyor system of a servo press installation, a motion controller for a conveyor system of a servo press installation, and to an associated computer program product, wherein an angular offset is optimized with respect to power peaks.

Claims

1. A method for motion planning for a conveyor system of a servo press installation including at least a first servo press and a second servo press, the conveyor system comprising at least one conveyor apparatus for movement of a product which is to be processed by the servo press installation, and motion of the at least one conveyor apparatus being controlled by a motion controller of the conveyor system, the method comprising: determining a motion segment, outside respective pressing workspaces of the at least one first servo press and the second servo press; defining a time interval for motion within said determined motion segment and motion from said at least one first servo press to the second servo press; calculating a motion curve for motion within the motion segment, with reference to the defined time interval.

2. The method as claimed in claim 1, wherein the motion segment is determined with reference to geometric data for the respective servo press and the conveyor apparatus, and, in particular, additionally for the product.

3. The method as claimed in claim 2, wherein the motion segment is additionally determined for the product.

4. The method as claimed in claim 1, wherein the time interval is defined by reference to data relating to an optimum offset between the at least one first servo press and the second servo press.

5. The method as claimed in claim 2, wherein the time interval is defined by reference to data relating to an optimum offset between the at least one first servo press and the second servo press.

6. The method as claimed in claim 3, wherein a minimum time interval is selected for the throughput of the product through the servo press installation as a first criterion for the optimum offset.

7. The method as claimed in claim 3, wherein a minimum overall peak power of the servo press installation is selected as a second criterion for the optimum offset.

8. The method as claimed in claim 6, wherein a minimum overall peak power of the servo press installation is selected as a second criterion for the optimum offset.

9. The method as claimed in claim 1, wherein a first position on a first margin of the motion segment at a starting time point of the time interval and a second position on a second margin of the motion segment at an end time point of the time interval are established as marginal conditions for the motion curve.

10. The method as claimed in claim 1, wherein the motion curve describes a translational motion.

11. The method as claimed in claim 1, wherein the motion curve describes a continuous motion.

12. The method as claimed in claim 1, wherein the motion curve is described via one of (i) polynomials, (ii) partially defined functions, (iii) point tables and (iv) non-linear scaled curve segments.

13. The method as claimed in claim 1, wherein the motion curve describes a constant-acceleration transition between the motion of the conveyor apparatus within the pressing workspace of the at least one first servo press and within the motion segment, and describes a constant-acceleration transition between the motion of the conveyor apparatus within the motion segment and within the pressing workspace of the second servo press.

14. A motion controller for a conveyor system of a servo press installation comprising at least a first servo press and a second servo press, the conveyor system comprising at least one conveyor apparatus for movement of a product which is to be processed by the servo press installation, the motion controller comprising: a storage unit for storing data on a motion segment outside respective pressing workspaces of the at least one first servo press and the second servo press; a delivery unit for delivering an instruction with respect to a time interval for motion within the motion segment and motion from the first servo press to the second servo press; and a calculation unit for calculating a motion curve for motion within the motion segment, with reference to the defined time interval.

15. The motion controller as claimed in claim 11, wherein the motion controller simultaneously controls a motion of at least one of (i) the at least one first and (ii) the second servo press.

16. A non-transitory computer-readable medium encoded with a computer program which, when executed by a processor of program-controlled device, causes motion planning for a conveyor system of a servo press installation including at least a first servo press and a second servo press, the conveyor system comprising at least one conveyor apparatus for movement of a product which is to be processed by the servo press installation, and motion of the at least one conveyor apparatus being controlled by a motion controller of the conveyor system, the computer program comprising: program code for determining a motion segment, outside respective pressing workspaces of the at least one first servo press and the second servo press; program code for defining a time interval for motion within said determined motion segment and motion from said at least one first servo press to the second servo press; and program code for calculating a motion curve for motion within the motion segment, with reference to the defined time interval.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The invention is described in greater detail hereinafter with respect to exemplary embodiments and with reference to the figures, in which:

[0043] FIG. 1 shows a schematic representation of a conveyor system within a press line, for the illustration of a method for motion planning in accordance with a first exemplary embodiment of the invention;

[0044] FIG. 2 shows a schematic representation of a conveyor system, with an associated controller, within a servo press installation, for the illustration of a method for motion planning in accordance with a second exemplary embodiment of the invention;

[0045] FIG. 3 shows a schematic representation of a process sequence of a method for motion planning for a conveyor system of a servo press installation in accordance with a third exemplary embodiment of the invention; and

[0046] FIGS. 4a-4c show the adjustment of a transfer motion curve to an exact angular offset, based on a conventional transfer motion curve.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0047] In the figures, functionally identical elements are identified by the same reference symbols, unless indicated otherwise.

[0048] FIG. 1 shows a sketch of a servo press installation or press line or pressing line PL, in which a first servo press P1 and a second servo press P2 are located. In the interests of clarity, further servo presses have been omitted from this representation. Realistically, more than two servo presses are present in a conventional servo press installation. Moreover, a conveyor system TS is outlined, which incorporates a transfer apparatus T, also described as a transfer system. A transfer apparatus T of this type is configured with a geometry that is adapted to a servo press and incorporates, for example, a moveable part, which is arranged within the transfer apparatus T, and which is appropriate for the accommodation of a product M which is to be processed, such as a workpiece that is to be pressed. For example, a gripper, a gripper arm, a clamp or a sucker of the transfer apparatus T grips the product or the workpiece M, for the conveyance thereof from the first servo press P1 to the second servo press P2. Here, the workpiece, likewise via the transfer system T, is introduced into the pressing workspace of the second servo press P2, and in particular is deposited there or positioned in a mold. Spatially, at least parts of the transfer apparatus T are thus temporarily located within the respective pressing workspace, for the extraction of the workpiece M, for example, of the material to be pressed, from the open first press P1 and the subsequent transfer thereof to the open second press P2.

[0049] In a first exemplary embodiment of the invention, it is intended that the overall time required for the passage of a processing product M through a plurality of servo presses, particularly the first servo press P1 and the second servo press P2, and further subsequent servo presses that are not represented, should be minimized. This means that the overall press line PL should deliver a finished processing product M at the maximum possible cycle rate. Processing of a workpiece M is completed, as soon as the workpiece has been transferred from the first processing station, for example the first servo press P1 within the press installation PL, to the final processing station, such as a final servo press, and has been processed to a finished state in all the stations.

[0050] For a design of the overall servo press installation PL of this type, in addition to the optimization of the individual forming processes on the individual servo presses, or additionally to the temporal optimization thereof, optimization of the motion of the conveyor system TS is also required. The maximum speed at which a processing product M can be conveyed from one servo press to the next servo press, for example, from the first servo press P1 to the second servo press P2, dictates the minimum offset that should be provided between these two servo presses, for the optimization of the throughput time.

[0051] In a particularly simple illustrative scenario, all the forming processes of all the servo presses involved occupy the same length of time, and the offset is zero, such that the complete conveyance process can be executed within a single press cycle. This is possible if the transfer system T is sufficiently rapid to complete the execution of the transfer of the workpiece from the first servo press to the second, and the return thereof to the first press, within a single press cycle. In many cases, however, the execution of such a rapid transfer is not possible.

[0052] If an offset greater than zero is set between the first servo press and the second servo press, then the overall time available to the transfer system remains identical. However, the ratio of the conveyance time to the return time changes, i.e., the conveyance time required for the conveyance of the product from the first servo press P1 to the second servo press P2 is greater, whereas the return time for this purpose is shorter. This permits the optimization of the throughput time, even in the event of longer conveyance times of the transfer system T.

[0053] It is assumed that, on the grounds of optimization with respect to the overall power required within the press installation PL, an offset between a first servo press 1 and a second servo press 2 will need to be enlarged. The time available to the transfer system T for material handling, in order to position the processing product M in the second servo press P2, should continue to be maintained so as to be as short as possible. At the same time, however, on the grounds of the greater offset to the second servo press P2, the transfer system T should be able to make an adjustment to motion planning.

[0054] The adjustment to motion planning is executed such that a motion segment between the first servo press P1 and the second servo press P2 is determined, during which the transfer system does not interact with the preceding transfer system or the subsequent transfer system, such that the time required for the complete loading and unloading process is not affected. This space is also dictated by geometrical factors of the servo press installation PL and the conveyor system TS. Additionally, this space is further limited by the quality of the product M to be processed, because only at the point in time at which the product to be unloaded can no longer delay the subsequent loading process that the overall time required for loading and unloading will not be extended.

[0055] It is thus ensured that a delay is only implemented if, for example, there is no resulting delay to the closure of a press, in particular as a result of a delay in a further conveyor system, which is also moved within the first pressing workspace, for the loading of the first servo press.

[0056] The segment of motion in the first servo press P1 is completed accordingly, can be executed exceptionally rapidly and, in this case, particularly remains unchanged. At the same time, the motion segment is completed, which the transfer system T is intended to execute exceptionally rapidly. Thereafter, the motion segment of the motion of the transfer system T commences, in which manipulation can be executed with no resulting disadvantage to the cycle rate of the servo presses, if the transfer system T can be driven at a correspondingly higher speed on the return path from the second servo press P2 to the first servo press P1, such that the delay can be recovered.

[0057] The overall performance of the press installation is thus maintained. The time required by the transfer system T for the motion from the first servo press P1 to the second servo press P2 is also described as the conveyance time, while that required for the return motion to the first servo press P1 is described as the return time. In particular, the conveyance time can also include the respective handling phase in the press, whether in whole or in part.

[0058] In an analogous manner, the motion segment of the second servo press P2 is delimited, because it terminates as soon as a delay in the transfer system, or in the workpiece to be processed, interacts with the subsequent transfer system for the unloading of the second servo press, such that there is a resulting extension of the overall time required for the loading and unloading process on the second servo press. For example, the motion segment of the second servo press can be constituted by the start of the pressing workspace of the second press, or by the point at which the workpieces, in consideration of their trajectory, cannot intersect at any time or, subject to trajectory, further into the interior of the press, provided that any collision on the grounds of the motion curve, and particularly in consideration of a rotation of the components, can be excluded. Here again, the subsequent motion described by the material handling system in the second servo press P2, in an advantageous manner, can continue to be executed at maximum speed. A temporal delay, of the type associated with the further offset between the first servo press P1 and the second servo press P2, only occurs, in an advantageous manner, within the motion segment determined.

[0059] The time interval is defined, in an exemplary manner, as follows: a minimum offset is initially determined with reference to a specific programming of the servo presses and the conveyor system. This minimum offset is defined by throughput time optimization. Additionally, an optimized offset is calculated with reference to energy management factors. The deviation of the optimized offset from a minimum offset is calculated therefrom, for example, as a correction angle. An extended conveyance time can be deduced therefrom and, from the latter, finally, the time interval for motion within the motion segment can be deduced.

[0060] Without affecting the times required by the transfer system T for the handling of material, the motion curve is thus adapted to the desired offset. In particular, motion curves are selected that ensure a jolt-free motion. C2-constant functions, for example, are suitable for this purpose, and are taken as the basis for a motion curve. With reference to marginal conditions, which are dictated by the motion profile of the transfer system during the unloading and loading on the first servo press or the second servo press, the appropriate motion curve can then be determined.

[0061] A second embodiment of the invention is described with reference to FIG. 2. A forward motion of the transfer system T, i.e., the motion of a product M that is to be processed within the servo press installation PL, is adjusted via a motion curve such that, in a quasi-deliberate manner, an offset is generated between the first servo press P1 and the second servo press P2. This offset effects an optimization of energy supply management, where an overall peak power of the servo press installation PL is reduced.

[0062] For example, between a plurality of servo presses within the servo press installation PL, and in particular between the first servo press P1 and the second servo press P2, the offset in the forming process motion can be set such that the overall performance of the servo press installation PL is no longer at a maximum, but instead the peak powers thereof, as associated with simultaneous or synchronously executed forming processes on a plurality of servo processes, are significantly reduced.

[0063] For example, this case occurs where the installation incorporates transfer systems between presses that have no facility for the compensation of a longer conveyance time by a shorter return time or waiting time within the return motion.

[0064] Configurations are also conceivable in which individual transfer systems and the offset with respect to associated presses in the installation are also optimized in consideration of the overall peak power, namely where, via the transfer systems, notwithstanding an extension of the conveyance time, no reduction in performance occurs, and individual transfer systems and the offset thereof with respect to the associated presses are only optimized with respect to the throughput time.

[0065] An analysis of the overall servo press installation PL, in which an optimum offset is determined, can advantageously precede motion planning. As soon as an offset between two servo presses is established, the method for motion planning for the conveyor system can be initiated. In the preceding determination of an optimum offset, an enlargement of an individual offset between two servo presses is generally undertaken, commencing from a minimum possible offset dictated by the capabilities of presses and transfer apparatuses.

[0066] FIG. 2 shows a schematic representation of a motion controller C for a conveyor system TS. In accordance with the second exemplary embodiment of the invention, the motion controller C is configured as a separate motion controller for the conveyor system TS, in addition to a further controller for the servo presses P1 and P2, which is not illustrated. The motion segment, which defines the region outside respective pressing workspaces, for each transfer apparatus T within a servo press installation PL, i.e., between the respective servo presses, can be individual or different in each case. In this regard, firstly, the geometry of the two servo presses involved, and secondly the geometry of the transfer apparatus, play a significant role. For example, the dimensions of the transfer apparatus T itself, for example, the length of the transfer apparatus T, or the dimensions, for example, in consideration of a gripper element, which are provided on the transfer apparatus T, are each different.

[0067] Additionally, even in the event of an identical geometry of the presses and transfer apparatuses involved, the motion segment, outside respective pressing workspaces, can vary within the press installation PL, because the product M to be processed by a sequential forming process within the servo press installation PL has differing dimensions. For example, a workpiece, further to a forming process, occupies more space on the transfer apparatus T, and the motion segment that describes the region outside respective pressing workspaces, or the region within which the motion of the transfer apparatus T executes a motion of the totality formed by the transfer apparatus T and the product M to be processed outside respective pressing workspaces, is correspondingly smaller.

[0068] For each transfer apparatus, the motion controller C of a conveyor system TS that comprises a plurality of transfer apparatuses holds the corresponding data for the associated motion segment. For example, data are stored in a storage unit 10. Advantageously, in the routine operation of a servo press installation PL, these data do not vary, or vary only slightly. The motion segment is to be determined separately for each transfer system T and, correspondingly, an associated data set for each transfer system T is to be stored in the storage unit 10. Retrieval can be executed, for example, upon the entry into service of the servo press installation PL.

[0069] The instruction regarding a time interval for motion within the motion segment is determined with reference to the issue of the offset. On the motion controller 10, for example, a delivery unit 20 is provided, which holds the instruction for the time interval. For example, an offset is communicated to the delivery unit 20 or the motion controller 10 via an input mask, with reference to which the delivery unit 20, in consideration of the times required for material handling, determines the time interval.

[0070] Finally, a calculation unit 30 is responsible for the calculation of an appropriate motion curve for motion within the motion segment. To this end, in particular, the interval is considered which, in the second exemplary embodiment of the invention, results in a desired enlarged offset for the minimization of power peaks. Moreover, the marginal conditions to be met, as in particular dictated by the material handling motion, are taken into consideration.

[0071] FIG. 3 shows a schematic illustration of a process sequence, which describes the method for motion planning for a conveyor system in accordance with a third exemplary embodiment of the invention. A first step S1 involves the determination of an appropriate motion segment, outside respective pressing workspaces of the first servo press and the second servo press. A second step S2 involves the definition of a time interval for motion within the motion segment, and from the first servo press to the second servo press.

[0072] The first step S1 and the second step S2 can be executed in any preferred sequence. For example, the determination S1 of a motion segment is executed only once whereas, conversely, the definition of a time interval S2 is executed regularly, or at specific intervals. Alternatively, both steps S1 and S2 can be executed with equal frequency.

[0073] The first step S1 of determining a motion segment can incorporate sub-steps, which comprise a measurement, particularly a survey of geometrical factors. Moreover, this determination can be executed purely on the basis of calculation using available geometric data or trajectory data. The definition of the time interval, as the second step S2, can incorporate a sub-step, which comprises a manual determination of an appropriate offset, for example, with reference to in-service tests conducted on the servo press installation. Moreover, the calculation of an optimum offset can be executed with reference to an algorithm, such that the definition of a time interval incorporates the processing of the result of such a calculation step.

[0074] The method described for motion planning for a conveyor system of a servo press installation is generally preceded by an optimization method, which determines the control of the servo presses at maximum speed of the conveyor system. For example, the operation of the servo press installation is optimized such that the highest possible performance is achieved where, in particular, the transfer apparatuses are operated as rapidly as possible such that, in particular, the loading and unloading processes occupy the least amount of time possible.

[0075] In an optimization of this type, for example, a motion curve for the transfer system is plotted, as represented in FIG. 4a. The time t is plotted on the horizontal axis, while the position x of the transfer system is plotted on the vertical axis. A time interval T0 for the transfer motion is thereby selected so as to be as short as possible.

[0076] On the basis of this optimization, in which, for example, only a uniform positioning set for a transfer apparatus can be assumed, the method for motion planning for a conveyor system is executed in an advantageous manner in accordance with the third exemplary embodiment of the invention, particularly in consideration of a specified and established time interval for motion within the motion segment, outside the respective pressing workspaces from a first servo press to a second servo press.

[0077] FIG. 4b illustrates this step where, for the motion of the transfer system, positions are determined that delimit or define the motion segment. To this end, for example, a first position x1 is determined, in which the workpiece is located immediately outside the first servo press or leaves the first pressing workspace. Moreover, a second position is determined, for example, in which the workpiece is not yet located in the second servo press, or is on the point of entering the second pressing workspace.

[0078] Accordingly, as illustrated in FIG. 4c, the motion curve is then adjusted to an optimally determined angular offset, where the motion curve is adjusted within the first position x1 and the second position x2. In this segment, motion is delayed, and assumes a second time interval T2 in place of a first time interval T1 that was previously required for the motion segment. The motion curve, for example, is adjusted to a curve with a constant speed and acceleration between the motion segments of the respective unloading and loading motion. As can be seen in FIG. 4c, the motion curve within the respective pressing workspaces remains unaffected, and is thus not subject to any delay.

[0079] Advantageously, in the application of the proposed method, an offset or angular offset between servo presses within a servo press installation is optimized in a targeted manner, without reducing a maximum achievable machine speed. To this end, in particular, the loading and unloading process on a servo press remains unaffected, and is executed with the maximum dynamics. Any offset that is additionally set via optimization can be compensated by a reduction in the waiting time in the return motion, or by the more rapid execution of the return motion. A deliberate delay outside the geometric pressing workspace particularly permits a conveyance of processing products between servo presses of a servo press installation that is optimized with respect to the energy management of the press.

[0080] In particular, by the determination of an optimum offset between two servo presses, power peaks in the presses are evened out, such that power peaks that are dictated per se by the motion profiles of the servo presses, such as braking or acceleration, or by the forming power, are not disadvantageously accumulated. Energy supply systems for the servo press installation can be optimized accordingly. For example, the input power or the size of the energy management system of the machine can be reduced to the greatest possible extent.

[0081] In sum, the disclosed embodiments of the invention relate to motion planning for a conveyor system of a servo press installation, a motion controller for a conveyor system of a servo press installation, and to an associated computer program product, in consideration of an angular offset that is optimized with respect to power peaks.

[0082] Although the invention has been illustrated and described in greater detail by means of exemplary embodiments, the invention is not limited by the examples disclosed, and further variations and combinations can be inferred by a person skilled in the art, without departing from the scope of protection of the invention.

[0083] Thus, while there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.