METHOD FOR COMPUTER-AID OPTIMIZATION OF TOOL TRANSPORTATION FOR AT LEAST ONE TOOL MAGAZINE WITH A NUMBER OF MAGAZINE PLACES

Description

[0001] The invention relates to a method and a device for computer-aided optimization of tool transport for at least one tool magazine having a number of magazine positions, which is used or can be used for a machine tool which is used for the production of one or more workpieces with the help of the tools provided by a magazine device at a staging station.

[0002] Modern machine tools enable the rapid production of various workpieces, closely aligned with customer demand. To ensure continuous production despite a wide variety of workpieces, these machine tools are equipped with large tool magazines.

[0003] When changing tools, the transport of the tools from the magazine to the spindle and back can lead to waiting times. To avoid such waiting times, the magazine capacity is adjusted. However, a magazine capacity that minimizes waiting time depends on the machine tool's program, i.e., the sequence and duration of use of the tools. If the program changes, for example, because a different product is to be produced, the magazine capacity must be adjusted.

[0004] According to DIN 69 651, a machine tool is a "mechanized and more or less automated manufacturing device that produces a predetermined shape on the workpiece or a change in a predetermined shape on a workpiece by means of relative movement between workpiece and tool" [ 6The machine tools considered in this context are preferably CNC lathes. These have a tool spindle in which the machining tool, also called the spindle tool, is located during machining. The tools that the machine can use to machine a workpiece are stored in a tool magazine. There are various types of tool magazines, such as chain or rack magazines. These magazines can hold a very large number of different tools; up to 500 tools or more.

[0005] In this context, we are considering shelf magazines. The tools are stored in fixed locations within them, from which they are retrieved and placed using a device (magazine handling unit). Unlike chain magazines, the access time to a tool is independent of the current magazine configuration. This type of magazine is therefore advantageous when a large variety of different workpieces are to be produced with a single machine, requiring a multitude of different tools.

[0006] In PCT / EP2018 / 074999, a tool reorganization within the magazine was already proposed, which requires a production shutdown. Figure 1 The figure, taken from the aforementioned patent application, shows a shelf magazine R with magazine locations or magazine positions P. A fictitious number of magazine positions is shown on the x-, y-, and z-axes.

[0007] A workpiece is machined using a predefined sequence of tools. A tool can appear multiple times in this sequence. While a workpiece is being machined with a tool in the sequence, the spindle tool, the preceding tool is returned to its position in the tool magazine and placed there. The spindle then moves to the location of the successor tool. This tool is then picked up and transported to the transfer point or staging area at the spindle. Once machining with the current spindle tool is complete, the tool is replaced in the spindle (e.g., using a tool changer). If machining with the spindle tool is finished but the successor tool is not yet available, a waiting time occurs for spindle replenishment, and the workpiece production time is extended.

[0008] The efficiency of a machine tool can be influenced by various factors. However, once the NC programs and the quantity of workpieces to be machined are fixed, machine efficiency is only affected by waiting times between successive machining steps (operations). These waiting times occur when, after machining with the spindle tool is complete, there is a delay because the next tool is not yet ready at the spindle transfer point. Therefore, magazine positions are assigned to the tools, which minimizes these waiting times.

[0009] Tools, in addition to their essential function as tools, have other characteristics and properties. They differ, for example, in size and weight. Therefore, shelf storage systems have different types of storage spaces to accommodate the corresponding tools. If tools are oversized, one or possibly even several adjacent storage spaces must be left empty. Furthermore, certain spaces in shelf storage systems may be blocked due to defects or structural features. A storage space can be occupied when it is free (not occupied by any tool) or becomes free; that is, a tool is moved to another storage space in that space so that it is free for the next tool.A permissible magazine configuration is an arrangement of tools in the magazine such that each tool occupies an available magazine position and the space requirements of adjacent tools do not overlap. Permissible magazine positions depend on the current occupancy of the tool magazine. Therefore, all permissible magazine positions are subject to additional restrictions: Only one tool may be placed in each magazine slot. The space required by the tool must not overlap with the space required by another, usually adjacent, tool in the magazine, nor may it protrude beyond the edge of the shelf magazine.

[0010] A minimum magazine load time depends on the workpieces to be produced and the associated NC programs. If production changes, the magazine load must be adjusted accordingly.

[0011] In [3], a reorganization of tools in the magazine has already been proposed, which requires a suspension of production. Figure 1 The aforementioned patent application also shows a shelf magazine.

[0012] If a new magazine configuration and a technically feasible tool changeover or transport sequence are available, this new magazine configuration can be configured after the current program has finished and before the next program has started. This means that production is paused until the reorganization is complete. This reduces the efficiency of the machine tool. Under certain conditions, the magazine reorganization can be performed while the current program is running without generating additional waiting times.

[0013] It is assumed that the time required to change a tool in the machine tool is relatively long compared to the machining time with that tool. Otherwise, there would be no waiting times for spindle replenishment, and the magazine load would have no impact on the machine tool's efficiency. Furthermore, it is assumed that the machining times of the individual program steps vary, resulting in waiting times for the magazine handling unit as well.

[0014] JPH0929575 discloses a method for rearranging a tool magazine.

[0015] The object of the invention is to provide a method and a device which enables the integration of tool changeover into the waiting times of the magazine operating device.

[0016] This task is solved by independent claims. Advantageous further training is the subject of dependent claims.

[0017] The invention claims a method for computer-aided optimization of tool reordering during production in at least one tool magazine having a number of magazine positions (P), which is used or can be used for a machine tool which is used for machining one or more workpieces with the aid of tools provided by a magazine operating device at a staging station, comprising the following steps: a) Recording a set of tools, b) Recording the space requirement for each tool, c) Recording a set of available magazine locations for each tool, wherein at least a subset of these includes permissible magazine locations that depend on the respective space requirements of the tools and the tools adjacent to each other, d) Recording a set of movement durations, each comprising a movement of the magazine handling device from one magazine location to another, or from a magazine location to the staging location, or from the staging location to a magazine location, e) Recording a permissible output magazine occupancy, wherein one output magazine location is recorded for each tool, f) Recording a set of tool transports from one magazine location to another permissible magazine location, wherein a tool transport from this set requires a movement duration, and establishing precedences, i.e.a partial ordering of tool transports, which requires that certain tools be transported to their next magazine position before other tools; g) determining a set of at least one available time interval, where an available time interval is a waiting time at the magazine handling device during a machining step of the workpiece and between depositing the last tool and picking up the next required tool; h) assigning the tool transports from the set of f) to the time intervals from the set of g) under the condition that the movement time for the tool transport is less than or equal to the length of the time interval, wherein the assignment is carried out by means of mixed-integer linear optimization taking into account the partial ordering of the tool transports, wherein the partial ordering of the tool transports is transferred to an edge set E of a graph G, i.e.A matching is performed, where (i, r) is an edge of G if and only if the tool transport r is possible in time interval i, where a maximum precedence-completed matching corresponds to a maximum executable sequence of tool transports that can be performed during the waiting times of the magazine handling device, where the solution of the mixed-integer linear optimization is the maximum matching with edge precedence, i) Performing at least one tool transport while the machine tool is in operation for machining a workpiece in a standby state or in a machining state, as soon as the machine tool reaches an operating state that has been or is assigned to one of the time intervals determined in g) and assigned in h).

[0018] It is possible to repeat step i) once or multiple times.

[0019] A partial ordering of the set of tool transports (see f)) is defined such that a tool transport not yet executed can be carried out once all tool transports previously ordered in the partial order have been executed. The partial ordering influences the assignment of at least one tool transport to a time interval according to h). The temporal sequence of the assigned time intervals should be consistent with the partial ordering of the tool transports.

[0020] The partial order results in a priority for a first tool, which must be moved to another free or soon-to-be-free magazine slot before a second tool can be moved to its magazine slot. To avoid irresolvable cycles or potential jams in the tool transport sequence, jams can be resolved, for example, by the procedure described in the aforementioned patent application PCT / EP2018 / 074999.

[0021] The aforementioned allocation of one or more tool transports or conversions to a time interval is performed using mixed-integer linear optimization, which is explained in more detail in the following exemplary implementations. Partial order is taken into account in the mixed-integer linear optimization.

[0022] Linear optimization is a special case of optimization methods. It deals with the optimization of linear objective functions over a set constrained by linear equations and inequalities. It forms the basis of the solution methods of (mixed-)integer linear optimization. A solver is a collective term for specialized mathematical computer programs that can solve mathematical problems numerically. In the context of MILP (mixed-integer linear programming), standard solvers such as CPLEX [3], Scip, Gurobi, and Xpress can be used for IP programs (integer optimization models). Typically, an initial configuration is specified, which is iteratively optimized to a target result. A nearest-neighbor heuristic can be used to determine the initial configuration of the MILP model.

[0023] The movement time can include both the transport time, which encompasses the movement of the magazine handling unit with a tool, and the empty travel time, which refers to the movement of the magazine handling unit without a tool. The transport time also depends on characteristics such as the size and weight of the tool being transported.

[0024] The time intervals in which multiple tool transports are possible can be further subdivided into time intervals in which, if possible, only one tool transport is carried out.

[0025] Another aspect of the invention relates to a control device for computer-aided optimization of a reordering of tools during production in at least one tool magazine having a number of magazine positions (P), which is used or can be used for a machine tool which is used for machining one or more workpieces with the aid of the tools provided by a magazine operating device at a staging station, comprising at least one processing unit which is set up to carry out a method according to one of claims 1-6.

[0026] The units designed to perform such process steps can be implemented in hardware, firmware and / or software.

[0027] Another aspect of the invention is a computer program (product) with program code means for carrying out the method according to one of the method claims 1-6, if it runs on a control device of the type mentioned above or is stored on a computer-readable medium.

[0028] The computer program or product can be stored on a computer-readable medium. The computer program or product can be written in a common programming language (e.g., C++, Java). The processing equipment can comprise a standard computer or server with appropriate input, output, and storage capabilities. This processing equipment can be integrated into the control unit or its components.

[0029] The control unit and the computer program (product) can be further developed or trained analogously to the above-mentioned procedure and its further developments.

[0030] Further advantages, details and developments of the invention will become apparent from the following description of exemplary embodiments in conjunction with the drawings. Figure 1 For example, the aforementioned shelf magazine, Figure 2 Figure 1 schematically shows a flowchart for the inventive method with steps 1 to 4, which are repeatable.

[0031] In Figure 1A rack magazine is shown. A magazine operating device, the tools, and the use of a tool to manufacture a workpiece are not shown. A control device (not shown) is conceivable that controls the machine tool (also not shown) which uses the rack magazine. This control device is designed to execute the process steps described in more detail below, or to control the machine tool with the magazine accordingly so that it can execute these process steps.

[0032] According to Figure 2The input IN comprises the quantity of tools, the space requirement of each tool, and a permissible output magazine capacity. In step 1, a set of available time intervals is determined. Within each time interval, the movement time of one or more tool transports is limited to a maximum of the machining time during which the tool (spindle tool) provided at the staging station is used to machine a workpiece.

[0033] In step 2, one or more tool transports are assigned to a specific time interval, provided that the movement time for the tool transport is less than or equal to the length of the time interval. In step 3, one or more tool transports are carried out. This can occur while the machine tool is in operation, either in a standby state or in a machining state, preparing to process a workpiece.

[0034] In addition, a set of movement durations, each comprising a movement of the magazine operating device from one magazine location to another magazine location or from one magazine location to the staging location or from the staging location to a magazine location, as well as a set of tool transports from one magazine position or location to another permissible magazine position, whereby a tool transport from this set requires a movement duration, is recorded as input IN.

[0035] The tool transport system is designed to move each tool from its current magazine location to its next location without collisions, taking into account its space requirements. This involves establishing precedence rules that require certain tools to be transported to their next location before others. The definition of precedence rules is explained in more detail below.

[0036] The following section will first explain a basic heuristic and the steps of the procedure according to the invention in more detail: Basic Heuristic Notation:

[0037] To simplify the description of the procedure, the notation described below is used. Index sets

[0038] Number of available time intervals Number of tool conversions Number of permissible magazine positions parameter

[0039] T i s , T i f Start and end times of interval i ∈ L i s , L i f Possible start and end positions of an interval i ∈ W r t Implementation tool r ∈ W r s Previous magazine position of tool W r t for implementation r ∈ W r f New magazine position of tool W r t for implementation r ∈ moveTime l , l ′ t Travel time for implementing the tool t from position l in position l' moveTime l,l' Travel time of an empty run from position l to position l ' loc ( t ) Quantity of all magazine positions of tool t during the tool implementations l 0< Position of the transfer point to the spindle ρ Maximum time of a sequence of idle and tool repositioning cycles parameters, λ ≈ 2, for the definition of λ -lazy operations

[0040] Be t 1 and t 2 two tools used during the operation o to be exchanged at the handover point. The time for returning the tool. t 1 to its magazine position, the empty run of the magazine operating device to the position of the following tool t 2 The transport of this tool to the transfer point is called the cycle time. It is determined by the magazine positions of the two tools. t 1 and t 2 dependent and generally takes a few seconds. Is the processing time of the operation o If the cycle time is shorter than the maximum cycle time of the magazine handling device, then o critical It's called an operation. o is called λ -lazy if the processing time of o larger than the λ -times the maximum cycle time, λ > 1. The tool pair ( t 1 , t 2 ) is analogous as critical or λ -lazy Tuples are defined as... λ = 2 Is the waiting time, for example, long enough to allow for any tool change during the processing of o to carry out. Determining the available time intervals:

[0041] To rearrange tools during production without causing additional downtime, waiting times are necessary at the magazine handling unit. This waiting time, between depositing the last tool and picking up the next required tool, is available for further operations of the magazine handling unit.

[0042] Be λ ≈ 2 and oi , i = 1, ... n, the amount of λ Lazy operations sorted in ascending order by their start time. Spindle tools before and after operation. oi be t i s and t i f That is, the tools t i s and t i f will be during the operation oi exchanged at the handover point. The number of available time intervals. be J = 1 , … , n where the possible start and end positions or times for time interval i are given by: L i s = loc t i s L i f = loc t i f T i s = Startzeit von o i + max moveTime t i s l 0 , l l ∈ L i s T i f = Endzeit von o i − max moveTime t i f l 0 , l l ∈ L i f Tool relocation sequence: Once the current and desired subsequent tool assignments to magazine positions are defined, the relocation sequence must be determined. It is assumed that each tool is relocated directly from its current magazine position to the next magazine position. By fixing the initial and target magazine assignments, the following two scenarios are possible: 1. Some tools must first be moved from their original magazine slot before another tool can be placed on it. 2. There are cyclical dependencies; that is, a tool must be moved from its original magazine slot in order to be moved itself.

[0043] In the first case, precedences are defined between the tool implementations; that is, the tool implementations are partially ordered. The implementation r 'is smaller than r , r ' ≺ r , if r' mandatory before r must be implemented. Are r' and r not comparable, i.e., neither applies r ' ≺ r still r ≺ r', This allows the implementation of r and r ' can be carried out in both sequences.

[0044] In the second case, it may not be possible to achieve the desired assignment simply by rearranging tools, for example, with shelf storage systems that have few free spaces and tools that require more than one storage space. If cyclical dependencies occur, they should be eliminated.

[0045] Removal of Transport Cycles: Transport cycles can be removed in various ways. Direct removal is achieved by adjusting the target magazine allocation. This approach can be taken from the aforementioned patent application and applied in this context as well. Potential transport cycles can be efficiently located using a depth-first search with polynomial runtime. All tools within a cycle are not transferred but remain in their positions. Likewise, all tools that previously required the transfer of a tool from a cycle are not transferred and remain in their positions. The resulting modified subsequent assignment of tools to magazine positions no longer contains any cyclic dependencies, and the tool transfers are partially ordered.

[0046] Alternatively, the restriction that each tool is transported directly from its current magazine position to its final magazine position can be lifted. A tool can thus be moved multiple times, and this additional freedom generally makes it possible to find a cycle-free set of tool moves. In the corresponding partial order, all tool moves for one and the same tool are totally ordered. However, in magazines with very few free spaces and many tools that require more than one shelf space, it may still be necessary to remove tools from the magazine to create the desired subsequent magazine layout.

[0047] In the following, it is assumed that a partially ordered set of tool implementations without cyclic dependencies is given. Modeling the tool implementation:

[0048] Be G = ( ∪ , E ) a bipartite graph with the node partitions and and the set of edges E . Where ( i , r ) exactly then edge of G is when the implementation of tool W r t in the time interval i is possible in terms of time, i.e., tool W r t is in the time interval i not a spindle tool and the following inequality is satisfied: max moveTime l , W r s l ∈ L i s + moveTime W r s , W r f W r t + max moveTime W r f , l l ∈ L i f ≤ T i f − T i s

[0049] The partial order of will be applied to the edge set E of the graph G transferred. For two edges ( i , r ), ( i ', r ') ∈ E applies: i ′ , r ′ ≺ i r ↔ T i ′ f < T i s ∧ r ′ ≺ r

[0050] A matching M of the graph G is closed with respect to <- if for all edges ( i,r ) ∈ M applies: r ′ ≺ r → ∃ i ′ , r ′ ∈ M : i ′ , r ′ ≺ i r

[0051] Each completed matching M defines an executable sequence of tool implementations = { r | ( i,r ) ∈ M}.A maximum <-completed matching thus corresponds to a maximum executable sequence of tool conversions that can be performed during the magazine handling unit's waiting times. This maximum is valid under the assumptions that only one conversion occurs during a waiting time and that the interval i Tools exchanged at the staging or handover point should remain in their original places in the magazine. Modeling as MIP

[0052] Determining a matching with edge precedence can be modeled as an integer linear program (MIP). Based on the notation introduced above, the following variables are defined: variables x ( i,r ) Indicator variable, whether edge ( i,r ) ∈ E in the matching process

[0053] A maximum matching with edge precedence is the solution of the integer linear program with the objective function max ∑ i r ∈ E x i r taking into account the following constraints: ∑ r ∈ R : i r ∈ E x i r ≤ 1 , i ∈ J ∑ i ∈ J : i r ∈ E x i r ≤ 1 , r ∈ R x i r ≤ ∑ i ′ ∈ J : i ′ , r ′ ∈ E i ′ , r ′ ≺ i r x i ′ , r ′ , i r ∈ E , r ′ ≺ r x i r ∈ 0 1 , i r ∈ E

[0054] For a permissible solution x be M x = {( i,r ) | x ( i,r ) = 1} ⊂ E The set of edges whose indicator variable x equals 1. Inequalities (6) and (7) guarantee that no two edges from M x an interval i or a tool implementation r be assigned, i.e. M x is a matching. The inequalities (8) ensure that the matching M x regarding <abgeschlossen ist. Somit ist an executable sequence of tool implementations that is ultimately consistent with the aforementioned partial order.

[0055] There are commercial and freely available solvers for solving mixed-integer linear programs [2,3]. That is, these solvers can compute a solution for the integer linear program described above for given coefficient values ​​and without further user intervention. Thus, maximum sequences of tool transfers can be calculated that are executed during the waiting times of the magazine handling device. Extensions of the heuristic Taking program progress into account:

[0056] A maximum <-completed matching corresponds to an executable sequence of tool transfers. However, these transfers can begin at the start of the currently running program. This alters the minimum magazine occupancy determined for this program and can lead to waiting times during production that were originally intended to be avoided. To prevent this undesirable effect, the objective function is modified. In other words, tool transfers are given increasing weight over time when performing a single tool transfer, provided that the cumulative waiting time for the magazine handling device decreases over time due to the tool being reassigned to a new magazine position after the tool transfer. Index sets T Set of tools contained in a critical tuple ( t ) Number of tool end-of-use dates t in a critical tuple

[0057] Be w : J × R → ℝ a weight function on the edges E of the graph G . The values ​​of w are defined as follows: w i r = − 1 falls W r t ∈ T ∧ T i f < max F t 1 falls W r t ∈ T ∧ T i f ≥ max F t 0 sonst

[0058] Using the weight function w The above objective function (5) of the integer program can be reformulated: max ∑ i r ∈ E w i r x i r

[0059] This creates a matching edge. ( i,r ) It only has a positive impact on the objective function if the associated tool implementation r only after the last use of the tool W r t is completed in a critical tuple. However, if the tool W r t even after the end of the implementation interval T i f still used in a critical tuple, the matching edge carries ( i,r ) negatively impacts the weight of the matching. Weighted consideration of program progress:

[0060] The objective function (11) weights all time points before (after) the last use of a tool from a critical tuple equally. This does not take into account that a single short waiting time before the program ends is less relevant.

[0061] Be ω ( i , r ) an estimate of the additional waiting time in the current program if the tool W r t currently T i s is implemented. Let Ω be a scaling parameter and the weight function. w ˜ : J × R → ℝ on the edges E of the graph G defined as follows: w ˜ i r = 1 − w i r Ω

[0062] If Ω is chosen to be approximately the size of the average waiting time savings per tool from a critical tuple, then ( i,r ) a negative weight w̃ ( i , r ), if an implementation of W r t currently T i s The estimated additional waiting time required during the currently running program is greater than the average savings per tool achieved through implementation. The estimates do not need to be precise; the important thing is to understand the relative ratios between different tool implementations. r and r ' and the decrease corresponds to the program progress. Therefore, with a suitable choice of the scaling parameter Ω, the objective function (5) of the integer program from section 4.5 are replaced by the following objective function (12). max ∑ i r ∈ E w ˜ i r x i r Multiple intervals:

[0063] The above model allows for a maximum of one tool change during the magazine operator's waiting time per operation. If the program includes longer operations and thus longer magazine operator waiting times, solutions with only one change can be very inefficient. In this case, the model can be extended.

[0064] When determining the time intervals, each λ-lazy operation is assigned an interval. Very long time intervals, which may include several tool transfers, are subsequently divided into several smaller time intervals, in which, if possible, only one tool transfer or transport is performed.

[0065] Be ρ the maximum travel time of an empty run and a tool relocation run, i.e. ρ = max moveTime l , W r s + moveTime W r s , W r f W r t r ∈ R , l ∈ L

[0066] A time interval i ∈ is called long time interval, if for a k = 2,3,... applies T i f − T i s ≥ kρ + max moveTime l , l ′ l , l ′ ∈ L

[0067] Be i a long time interval and k maximum, so that inequality (14) holds. The interval i will be in k Intervals with a length of ρ and ρ + moveTime l,l' subdivided. The start time (possible starting positions) of the first and the end time (possible ending positions) of the last new interval are T i s L i s or T i f L i f . The intermediate times and positions depend on the tool change selected for the preceding time interval. Since all intervals are at least the length ρ Any sequence of a travel and a tool repositioning can be performed within the interval. In the last time interval, an additional travel to any position can be performed. L i f This partitioning is performed for each long time interval. The resulting interval set is then... '.

[0068] The bipartite graph is displayed on 'extended. Since every tool implementation is possible in the newly created sub-intervals, the following applies to these intervals. i ' all edges ( i' ,r ) in the graphs G inserted for the W r t not the spindle tool, during the time interval i is. For the unchanged time intervals i and tool implementations r The above criterion (2) continues to be applied. This extended bipartite graph also has the property that each <-completed matching corresponds to an executable sequence of tool implementations.

[0069] The implementation of the processes or procedures described above can be carried out using instructions stored on computer-readable storage media or in volatile computer memory (hereinafter collectively referred to as computer-readable memory). Examples of computer-readable memory include volatile memory such as caches, buffers, or RAM, as well as non-volatile memory such as removable media, hard drives, etc.

[0070] The functions or steps described above can be represented in the form of at least one instruction set in / on computer-readable memory. These functions or steps are not bound to a specific instruction set, a specific form of instruction sets, a specific storage medium, a specific processor, or specific execution schemes, and can be executed by software, firmware, microcode, hardware, processors, integrated circuits, etc., either independently or in any combination. Various processing strategies can be employed, such as serial processing by a single processor, multiprocessing, multitasking, or parallel processing, etc.

[0071] The instructions can be stored in local memory, but it is also possible to store the instructions on a remote system and access them via a network.

[0072] In the context of the invention, "computer-aided" can, for example, be understood to mean an implementation of the method in which, in particular, a processor performs at least one process step of the method.

[0073] The terms "processor," "central signal processing," "control unit," or "data processing device," as used herein, encompass processing devices in the broadest sense, including, for example, servers, general-purpose processors, graphics processors, digital signal processors, application-specific integrated circuits (ASICs), programmable logic circuits such as FPGAs, discrete analog or digital circuits, and any combination thereof, including all other processing devices known to those skilled in the art or which may be developed in the future. Processors may consist of one or more devices, units, or components. If a processor consists of several devices, these may be designed or configured for parallel or sequential processing or execution of instructions. In the context of the invention, a "memory unit" may, for example, refer to a memory in the form of main memory (RAM).Random-Access Memory (RAM) or a hard drive. References:

[0074] 1. PCT / EP2018 / 074999 2. The SCIP Optimization Suite 5.0; Ambros Gleixner, Leon Eifler, Tristan Gally, Gerald Gamrath, Patrick Gemander, Robert Lion Gottwald, Gregor Hendel, Christopher Hojny, Thorsten Koch, Matthias Miltenberger, Benjamin Müller, Marc E. Pfetsch, Christian Puchert, Daniel Rehfeldt, Franziska Schlösser, Felipe Serrano, Yuji Shinano, Jan Merlin Viernickel, Stefan Vigerske, Dieter Weninger, Jonas T. Witt, Jakob Witzig, ZIB-Report 17-61, Zuse Institute Berlin, December 2017; http: / / scip.zib .de 3. IBM ILOG CPLEX MIP Optimizer; https: / / www.ibm.com. 4. Andreas Hirsch; Machine Tools: Fundamentals, Design, Examples, 2nd ed., Springer Vieweg | Springer Fachmedien Wiesbaden 2012, p. 2; https: / / doi.org / 10.1007 / 978-3-8348-2364-9.

Claims

1. Method for the computer-aided optimization of a re-sorting of tools during production in at least one tool magazine having a number of magazine locations (P), which is used or is usable for a machine tool that is employed for the processing of one or more workpieces with the aid of the tools provided by a magazine operating apparatus at a provision location, having the following steps: a) recording a set of tools, b) recording the space requirement for each tool, c) recording a set of occupiable magazine locations for each tool, at least one subset thereof comprising allowed magazine locations which are dependent on the respective space requirement of the tools and of the tools respectively neighbouring one another, d) recording a set of movement time durations which respectively comprises a trip of the magazine operating apparatus from one magazine location to another magazine location or from a magazine location to the provision location or from the provision location to a magazine location, e) recording an allowed initial magazine occupancy, an initial magazine location for each tool being recorded, f) recording a set of tool transports from one magazine position to another allowed magazine position, a tool transport from this set requiring a movement time duration, and defining precedences, that is to say a partial order of the tool transports that requires particular tools to be transported before other tools to their next magazine location, g) determining a set of at least one available time interval, an available time interval being a waiting time in the magazine operating apparatus during a step of processing the workpiece and between depositing the last tool and taking up the next tool, h) allocating the tool transports from the set of f) to the time intervals from the set of g) under the condition that the movement time duration for the tool transport is less than or equal to the length of the time interval, the allocation being carried out by means of mixed integer linear optimization, taking into account the partial order of the tool transports, the partial order of the tool transports being applied to an edge set E of a graph G, that is to say a matching is carried out, where (i, r) is the edge of G precisely when the tool transport r is chronologically possible in the time interval i, where a maximum matching that is bounded with respect to the precedence corresponds to a maximum performable sequence of tool transports that can be carried out during the waiting times of the magazine operating apparatus, the solution to the mixed integer linear optimization being the maximum matching with edge precedences, i) carrying out the at least one tool transport while the machine tool for the processing of a workpiece is in operation in a ready state or in a processing state, as soon as the machine tool reaches an operating state which has been assigned or is assigned to one of the time intervals determined in g) and allocated in h).

2. Method according to Claim 1, characterized in that the partial order of the set of tool transports is specified such that a tool transport that has not yet been performed may be performed when all tool transports previously arranged in the partial order have been performed.

3. Method according to Claim 1 or 2, characterized in that the chronological succession of the allocated time intervals is consistent with the partial order of the tool transports.

4. Method according to one of the preceding claims, characterized in that a movement time duration includes both a transport time duration, which comprises a trip of the magazine operating apparatus with a tool, and an empty trip time duration, which comprises a trip of the magazine operating apparatus without a tool.

5. Method according to the preceding claim, characterized in that the transport time duration additionally depends on properties of the tool to be transported.

6. Method according to one of the preceding claims, characterized in that the time intervals in which a plurality of tool transports are possible are subdivided into further time intervals in which, if possible, only one tool transport is carried out.

7. Control instrument for the computer-aided optimization of a re-sorting of tools during production in at least one tool magazine having a number of magazine locations (P), which is used or is usable for a machine tool that is employed for the processing of one or more workpieces with the aid of the tools provided by a magazine operating apparatus at a provision location, having at least one processing unit which is designed to perform a method according to one of the preceding claims.

8. Computer program product having program code for carrying out the method according to one of the preceding Method Claims 1-6 when it runs on a control instrument according to Claim 7 or is stored on a computer-readable medium.