阅读说明：本技术 用于以计算机辅助的方式优化工具对库空间的占用的方法和设备 (Method and apparatus for computer-aided optimization of tool occupancy of library space ) 是由 G·拜尔 L·胡普 C·罗耶 S·贝歇尔 于 2019-03-01 设计创作，主要内容包括：本发明涉及一种用于以计算机辅助的方式优化用于工具机的至少一个工具库(R)之内的工具对库空间(P)的占用的方法,其中借助由库设备在提供空间处提供的工具来制造一种或多种工件类型的一个或多个工件,所述方法具有以下步骤：a)检测要制造的工件的集合,b)检测至少一个工具库(R)中的库空间(P)的集合,c)检测工具的集合,d)检测每个工具的空间需求和必要时至少一个其他特性,e)检测每个工具的允许的库空间,其中允许的库空间取决于所述工具的空间需求和/或其他特性和/或所述库空间的所检测到的特性,f)检测允许的初始库占用,其中针对每个工具检测初始库空间,g)检测要由所述工具机在工件处执行的工作步骤的序列,其中针对该序列的工作步骤所设置的工具被用于制造所述工件,h)检测分别用于在所述工件处执行单个工作步骤所需的工作步骤时长,i)根据要执行的工作步骤的序列并且根据分别针对由库设备在所述提供空间处为后续的工作步骤提供工具所需的库占用,检测一个或多个提供时长,j)优化工具对所述库空间的占用,其中每个工具只能无冲突地占用允许的库空间,使得总等待时间被最小化,其中如果所检测到的提供持续时间与所检测到的工作步骤时长之间的差的值为正,则总等待时间由分别由所述差得出的各个等待时间组成,要不然各个等待时间采取零值,其特征在于,k)执行工具对所述库空间的占用的优化,使得所述工具无冲突地被放置在所述初始库占用的相同库空间上或在其以前占用的库空间附近的允许的库空间上。(The invention relates to a method for computer-assisted optimization of the occupation of a tool-specific library space (P) within at least one tool library (R) for a machine tool, wherein one or more workpieces of one or more workpiece types are produced by means of a tool provided by a library system at a provision space, comprising the following steps: a) detecting a set of workpieces to be produced, b) detecting a set of library spaces (P) in at least one tool library (R), c) detecting a set of tools, d) detecting a spatial requirement and optionally at least one further property of each tool, e) detecting an allowed library space of each tool, wherein the allowed library space depends on the spatial requirement and/or the further property of the tool and/or the detected property of the library space, f) detecting an allowed initial library occupancy, wherein an initial library space is detected for each tool, g) detecting a sequence of work steps to be performed by the machine tool at a workpiece, wherein the tools provided for the work steps of the sequence are used for producing the workpieces, h) detecting a work step duration required for performing a single work step at the workpiece in each case, i) according to the sequence of work steps to be performed and according to the provided space in each case by a library apparatus -detecting one or more offered durations for subsequent work steps, j) optimizing the occupation of the library space by tools, wherein each tool can only occupy the allowed library space without conflict, such that the total waiting time is minimized, wherein if the value of the difference between the detected offered duration and the detected work step duration is positive, the total waiting time consists of individual waiting times respectively derived from said difference, otherwise the individual waiting times assume zero values, characterized in that k) optimizing the occupation of the library space by tools is performed such that the tools are placed without conflict on the same library space occupied by the initial library or on allowed library spaces in the vicinity of the library space previously occupied by them.)

1. A method for computer-aided optimization of the occupation of a library space (P) by tools within at least one tool library (R) for a machine tool, wherein one or more workpieces of one or more workpiece types are produced by means of the tools provided by a library device at a provision space, having the following steps:

a) a set of workpieces to be manufactured is detected,

b) detecting a set of library spaces (P) in at least one tool library (R),

c) a collection of detection tools is provided that detect,

d) the spatial requirements and if necessary at least one other characteristic of each tool are detected,

e) detecting an allowed library space for each tool, wherein an allowed library space depends on the spatial requirements and/or other characteristics of the tool and/or the detected characteristics of the library space,

f) detecting an allowed initial library occupancy, wherein the initial library space is detected for each tool,

g) detecting a sequence of work steps to be performed by the machine tool at a workpiece, wherein a tool provided for a work step of the sequence is used for producing the workpiece,

h) detecting the work step durations required for performing individual work steps at the workpiece,

i) detecting one or more provision durations according to a sequence of work steps to be performed and according to a library occupation respectively required for providing a tool for a subsequent work step at the provision space by a library device,

j) optimizing the occupation of the library space by the tools, wherein each tool can only occupy the allowed library space without conflict, such that the total waiting time is minimized, wherein if the value of the difference between the detected provision duration and the detected work step duration is positive, the total waiting time consists of individual waiting times respectively derived from the difference, otherwise the individual waiting times assume zero values,

it is characterized in that the preparation method is characterized in that,

k) optimization of the occupancy of the library space by a tool is performed such that the tool is placed, without conflict, on the same library space occupied by the initial library or on an allowed library space near the library space it previously occupied.

2. Method according to the preceding claim, characterized in that the weighting between steps j) and k) is performed.

3. The method of any preceding claim in which the detected characteristics for each allowed library space comprise a level in the hierarchical order for each tool dependent on the respective library space type such that the sum for the levels is optimised.

4. Method according to the preceding claim, characterized in that the weighting between steps j), k) of claim 1 and steps of claim 3 is performed.

5. The method of any one of the preceding claims, wherein the provision duration consists of a take duration comprising a duration for taking a tool from one respective library space allowed for the tool to the provision space by the library appliance, and of a put duration comprising a duration for putting a tool from the provision space back to one respective library space allowed for the tool by the library appliance, and of an idle stroke duration for an idle stroke of the library appliance from a first library space to another second library space.

6. Method according to any of the preceding claims, characterized in that the tool is relocated by a library device of the machine tool according to the optimized occupancy.

7. Method according to any of the preceding claims, characterized in that the mentioned optimization is performed by means of mixed integer linear optimization.

8. Method according to any of the preceding claims, characterized in that a set of library spaces is detected, which library spaces are each fixedly occupied by a tool.

9. Method according to any of the preceding claims, characterized in that the detected characteristic of each tool comprises a weight and that for each library column consisting of a set of library spaces a maximum load is predefined and/or can be predefined such that it is lower each time a tool in the library occupies a library space.

10. Method according to one of the preceding claims, characterized in that target magazine spaces are respectively allocated to critical tools according to the optimized occupation, for which critical tools the mentioned waiting times take values greater than zero, and in addition the set of transport durations respectively required for the journey of the magazine apparatus from one magazine space to another is detected,

a) wherein a set of vehicle transports is determined for which a predefined or predefined transport order can be specified, such that the critical vehicle or a subset thereof can be brought in this transport order from its occupied depot space to its target depot space without conflict with regard to its space requirement, and

b) wherein the transport order of the set of vehicle transports is optimized such that the sum of the transport time periods required for the vehicle transports is minimized.

11. Method according to any of the preceding claims, characterized in that at least one key tool from the set of detected tools is transported without conflict from the library space occupied by said key tool to another occupiable library space, in order to determine a subset of at least one single element of a tool transport according to step a) of claim 10 and to continue with step b) of claim 10.

12. Method according to any of the preceding claims 10 or 11, characterized in that at least one critical tool from the set of detected tools that stays at the library space occupied by it, but should be transported without collision to another occupiable library space, is placed on the library space in the vicinity of the library space calculated according to step k) of claim 1, wherein the set of tool transports can be determined according to step a) of claim 10 such that the total waiting time is minimized.

13. Method according to any of the preceding claims, characterized in that the transport of the tool is performed by means of the library device according to an optimized transport sequence.

14. A control device for computer-assisted optimization of the tool occupancy of a magazine space (P) within at least one tool magazine (R) for a machine tool, wherein one or more workpieces of one or more workpiece types are produced by means of tools provided by a magazine apparatus at a provision space, the control device having:

a) a first unit for detecting a set of workpieces to be manufactured,

b) the same or a second unit for detecting a set of library spaces (P) in at least one tool library (R),

c) the same or a third unit for detecting a set of tools,

d) the same or a fourth unit for detecting the spatial requirements and if necessary at least one further characteristic of each tool,

e) the same or a fifth unit for detecting an allowed library space for each tool, wherein an allowed library space depends on the spatial requirements and/or other characteristics of the tool and/or the detected characteristics of the library space,

f) the same or a sixth unit for detecting allowed initial library occupancy, wherein the initial library space is detected for each tool,

g) the same or a seventh unit for detecting a sequence of work steps to be performed by the machine tool at a workpiece, wherein a tool provided for a work step of the sequence is used for manufacturing the workpiece,

h) the same or an eighth unit for detecting the duration of the work steps respectively required for carrying out a single work step at the workpiece,

i) the same or a ninth unit for detecting one or more offered durations according to the sequence of work steps to be performed and according to an initial library occupation respectively required for the tool offered by the library apparatus for a subsequent work step at the offered space,

j) an optimization unit for optimizing the tool's occupation of the library space, wherein each tool can only occupy the allowed library space without conflict, such that the total latency is minimized, wherein if the value of the difference between the detected provision duration and the detected work step duration is positive, the total latency consists of individual latencies which are respectively derived from the difference, otherwise the individual latencies assume zero values,

it is characterized in that the preparation method is characterized in that,

k) executing another optimization unit for optimizing the occupation of the library space by the tool such that the tool is placed without conflict on the same library space occupied by the initial library or on an allowed library space near the library space it previously occupied.

15. A computer program product having program code means for performing the method according to any one of the preceding claims when the computer program product is run on a control device according to any one of the preceding control device claims or stored on a computer readable medium.

Technical Field

The invention relates to a method and a device for computer-assisted optimization of the tool-to-library space (Magazinpl ä tzen) occupation of at least one tool library for a machine tool, wherein one or more workpieces of a workpiece type are produced by means of a tool provided by the library device at a supply space.

Background

A machine tool is an automated production device with which a predefined shape is produced on a workpiece by means of one or more tools. Multiple tools may be associated with one tool type, e.g., milling. Another tool type may be, for example, drilling. The machine tool has a tool spindle in which a machining tool, also referred to as a spindle tool, is located during machining.

Tools that can be used by the machine tool to machine a workpiece are stored in a tool magazine. There are different types of tool libraries. A very frequently used form is a chain library, which is used, for example, in the automotive industry.

Another library type is a rack library R, such as that indicated in fig. 1, in which a very large number of different tools (up to 500 tools or possibly even more) can be placed. In which the tools are stored on a fixed magazine space P. Such a library may be comprised of a primary side and an opposing corresponding side.

A rack magazine has a device, in particular a magazine device, which is not shown in fig. 1 and with which tools can be stored on its magazine space P and taken. This library type is used in particular if a large variety of different tools, for which a large number of different tools are required, should be produced with the machine tool.

The machining of the workpiece, which determines the workpiece type, is carried out using a predefined tool sequence. A tool can be present here exactly several times in the sequence. The sequence is the same for all workpieces of a workpiece type, for example a car seat. The sequence may be different for workpieces of other workpiece types.

During a work step of machining a workpiece with the tool, spindle tool of the sequence, in the rack magazine the "predecessor tool" of the previous work step is returned or put back on its magazine space. Subsequently, an empty run of the library space of the "successor tool" to the subsequent work step is carried out. The successor tool is then picked up and transported to provide space. If the current working step, i.e., machining, with the current spindle tool is finished, the tool in the spindle is replaced (e.g., with a tool changer). If the machining with the spindle tool is finished, but a subsequent tool for a subsequent working step is not yet ready, a waiting time is generated in the case of spindle supply. Each waiting time reduces machine efficiency and increases production duration. These latencies should be avoided.

In the case of minimizing the waiting time in the case of a spindle feed during the production of a predefined or predefinable set of workpieces of one or more workpiece types, the following restrictions should be noted.

Due to technical limitations, the tools cannot be placed arbitrarily in the magazine, but rather have to be stored accordingly to their space requirement, for example to their tool radius and other requirements. Such a requirement may be, for example, the weight of the tool or the length of the tool due to the characteristic(s) of the tool. The property(s) of the library space, such as the maximum load or edge space, should match the properties of the tool. Finding the allowed space allocation for a tool in a complete large library is a complex task.

The tool has other features in addition to its actual tool characteristics. The tools differ, for example, in size and weight. Thus, rack libraries have different types of spaces in order to accommodate the respective tools. In addition, in rack stores, certain spaces may be blocked due to imperfections or structural features. Therefore, various conditions must be satisfied when allocating space.

Tools are typically not allowed to be placed at any library space, i.e., there are allowed library spaces and disallowed library spaces for the tool or allowed and disallowed tools for each library space.

The allowed library occupancy is the arrangement of tools in the library such that each tool is on the occupiable space and the space requirements of the tools do not overlap. The allowed library space depends on the current occupancy of the tool library.

The library space type of the tool and the library space type of the library or shelf space must be compatible. Thus, for example, a large tool is not allowed to be placed on a library space for a small tool, and vice versa, if necessary.

The tool is not allowed to protrude at the edge.

Tools are not allowed to sit on the blocked library space.

If the tool is too large, one or possibly even more adjacent library spaces must be freed.

Non-conflicting with respect to space requirements means in this context that the vehicle can be transported or placed onto the allowed library space.

The initial case is usually a rack library (which may also be very full) filled with tools. In order to be able to note the above mentioned limitations, a shift or reclassification of the tools in the rack magazine is performed. This cannot be performed at peak hours (i.e. during ongoing production) and thus leads to downtime of the machine tool. In this context, it is expedient to allocate as many tools as possible again to the old library space.

A method for computer-aided optimization of the occupation of the magazine space by tools within at least one tool magazine for a machine tool has already been proposed in patent application PCT/EP 2017/073206. However, the problem solution described in this patent application requires a powerful computer or computer unit in order to be able to solve the optimization procedure described there.

The calculation of the optimal space allocation of the tool in the library is often performed on a not so powerful industrial PC with small memory space, such as an edge box. To avoid downtime during production, it must be possible to compute space allocation very quickly on such an industrial PC with a small amount of storage space.

Disclosure of Invention

The object of the invention is to improve the method mentioned at the outset.

This object is achieved by the independent claims. Advantageous developments are the subject matter of the dependent claims.

The invention relates to a method for computer-assisted optimization of the tool occupancy of a library space within at least one tool library for a machine tool, wherein one or more workpieces of one or more workpiece types are produced by means of a tool provided by a library system at a provision space, comprising the following steps:

a) a set of workpieces to be manufactured is detected,

b) detecting a set of library spaces in at least one tool library,

c) a collection of detection tools is provided that detect,

d) the spatial requirements and if necessary at least one other characteristic of each tool are detected,

e) detecting an allowed library space for each tool, wherein an allowed library space depends on the spatial requirements and/or other characteristics of the tool and/or the detected characteristics of the library space,

f) detecting an allowed initial library occupancy, wherein the initial library space is detected for each tool,

g) detecting a sequence of work steps to be performed by the machine tool at the workpiece, wherein the tool provided for the work steps of the sequence is used for manufacturing the workpiece,

h) the work step durations which are respectively required for carrying out individual work steps at the workpiece are detected,

i) according to the sequence of work steps to be performed and according to the respective required library occupation for the tool provision of the subsequent work step at the provision space by the library device, one or more provision durations are detected,

j) optimizing the occupation of the library space by the tools, wherein each tool can only occupy the allowed library space without conflict, such that the total waiting time is minimized, wherein if the value of the difference between the detected provision duration and the detected work step duration is positive, the total waiting time consists of individual waiting times respectively derived from said difference, otherwise the individual waiting times assume zero values,

it is characterized in that the preparation method is characterized in that,

k) optimization of the occupancy of library spaces by tools is performed such that the tools are placed, without conflict, on the same library space occupied by the initial library or on allowed library spaces in the vicinity of the library space they previously occupied.

The conflict-free occupation of the library space means: the space requirements of the tools are not allowed to overlap in step j). The duration of the minimized total waiting time should be maintained in the case of the execution of step k).

Placing near a previously occupied library space means that the duration of the transport from the previously occupied library space to the new library space is as small as possible.

Other characteristics may include weight and/or tool radius, which are considered separately in optimizing the tool's footprint of the library space.

The detected characteristic may comprise a weight for each tool, and for each bin column consisting of a set of bin spaces, the maximum load may be predefined and/or predeterminable such that the load is lower each time a tool in the bin occupies the bin space.

The detected characteristics for each allowed library space may also include a rank in a hierarchical order for each tool that depends on the corresponding library space type, such that the sum for the ranks is optimized. The sum of the levels is minimized or maximized according to the ordering (ascending or descending) of the order.

In this case, a higher level may imply a higher preference of the tool for the library space (Bevorzugung), such that the tool is placed on the preferred space with respect to its level.

The weighting between steps j) and k) and/or the above-mentioned steps should be done such that the duration of the total waiting time is minimized first.

The detected characteristic of the library space may be a determined space type, such as edge space, partial/half space, or maximum load weight. The maximum load weight can be a factor (roll) in considering the maximum load weight of a column or row of the library space.

The previously occupied library space may be the original library space and/or the predecessor library space.

The set of workpiece types and the number of pieces of workpieces to be manufactured for each workpiece type are detected and incorporated into the optimization of the tool's occupation of library space.

The invention has the advantages that:

shorter production time of o-machine tools

Shorter travel paths or provision durations for the library devices of the o-rack library, which ultimately lead to energy savings and longer durability.

The provision duration is composed of a removal duration, which includes a duration for removing a tool from a respective one of the available magazine spaces to the provision space by the magazine device, and of a removal duration, which includes a duration for removing a tool from the provision space to a respective one of the available magazine spaces by the magazine device, and of an idle travel duration, which is used for an idle travel of the magazine device from a first magazine space to a further second magazine space.

According to the above-mentioned optimized occupation, the tool can be replaced by the library device of the machine tool.

The mentioned optimization can be performed by means of mixed integer linear optimization.

A set of library spaces is detected, which are respectively fixedly occupied by the tools and which are not allowed to be occupied by other tools by optimization.

A further development of the invention provides that the target depot space is respectively allocated to critical tools for which the mentioned waiting times take values greater than zero, in accordance with the above-mentioned optimized occupation, and that furthermore a set of transport durations respectively required for the journey of the depot device from one depot space to another is detected,

a) wherein a set of vehicle transports is determined for which a predefinable or predefinable transport sequence is possible, such that the key vehicle or a subset thereof can be brought in this transport sequence without conflict with respect to its space requirement from its occupied library space (or initial library space) to its target library space, and

b) wherein the transport order of the set of vehicle transports is optimized such that the sum of the transport time periods required for the vehicle transports is minimized.

A further development of the invention provides that at least one key tool from the set of detected tools is transported without conflict from the library space occupied by said key tool onto another, occupiable library space, in order to determine a subset of at least one single element of the tool transport according to step a) above and to continue with step b) above.

"without conflict" in this context means: if a tool is assigned a different library space than the initial library space, the tool must be shifted or reclassified in the tool library without conflict.

A further development of the invention provides that at least one critical tool from the detected set of tools which remains at the library space occupied by it, but which should be transported without conflict to another, occupiable library space, is placed on the library space in the vicinity of the library space calculated according to step k) above, wherein the set of tool transports can be determined according to step a) such that the total waiting time is minimized.

The vehicle transport can be performed by means of the library device according to the optimized transport sequence.

Another aspect of the invention provides a control device which is designed in particular to carry out a method according to the type mentioned above and its embodiments. The control device (not shown in fig. 1) can be a computer assigned to the machine tool and arranged offset as required or a control module integrated into the machine tool.

Control device for computer-assisted optimization of the tool-to-library space occupation within at least one tool library for a machine tool, wherein one or more workpieces of one or more workpiece types are produced by means of a tool provided by a library system at a provision space, having:

a) first unit for detecting a set of workpieces to be manufactured

b) The same or a second cell for detecting a set of library spaces in at least one tool library,

c) the same or a third unit for detecting a set of tools,

d) the same or a fourth unit for detecting the spatial requirements and if necessary at least one further characteristic of each tool,

e) the same or a fifth unit for detecting for each tool an allowed library space, wherein the allowed library space depends on the spatial requirements and/or other characteristics of the tool and/or the detected characteristics of the library space,

f) the same or a sixth unit for detecting allowed initial library occupancy, wherein the initial library space is detected for each tool,

g) the same or a seventh unit for detecting a sequence of work steps to be performed by the machine tool at the workpiece, wherein the tool provided for the work steps of the sequence is used for manufacturing the workpiece,

h) the same or an eighth unit for detecting the duration of the work steps respectively required for carrying out a single work step at the workpiece,

i) the same or a ninth unit for detecting one or more provision durations depending on the sequence of work steps to be performed and depending on an initial library occupation respectively required for providing a tool at a provision space for a subsequent work step by the library apparatus,

j) an optimization unit for optimizing the tool's occupation of the library space, wherein each tool can only occupy the allowed library space without conflict, such that the total latency is minimized, wherein if the value of the difference between the detected provision duration and the detected work step duration is positive, the total latency consists of individual latencies which are respectively derived from said difference, or else the individual latencies assume the value zero,

it is characterized in that the preparation method is characterized in that,

k) another optimization unit for optimizing the tool's occupation of library space is executed such that the tool is placed, without conflict, on the same library space occupied by the initial library or on an allowed library space near its previously occupied library space.

Here, the first, second, third, fourth, fifth, sixth, seventh, eighth or ninth detection unit may be integrated into one detection unit in any combination with the second, third, fourth, fifth etc.

Another aspect of the invention is a computer program (product) having program code means for performing a method according to any one of the preceding method claims, when the computer program (product) is run on a control device of the above-mentioned type or stored on a computer readable medium.

The computer program or product may be stored on a computer readable medium. The computer program or product may be created in a standard programming language (e.g., C + +, Java). The processing means may comprise a commercially available computer or server having corresponding input, output and storage means. The processing means may be integrated in the control means or in the means thereof.

The control device and the computer program (product) may be modified or constructed similarly to the above-mentioned method.

Drawings

Further advantages, details and improvements of the invention emerge from the following description of an embodiment with reference to the drawing.

In the drawings:

fig. 1 shows the space mentioned at the beginning in a rack-like storage, with the main side arranged on the right and the corresponding side on the left,

fig. 2 schematically shows a flow chart for an iterative method with a starting configuration, in which an integer linear optimization method is applied,

FIG. 3 schematically shows a flow chart for computing a tool transfer list, an

Fig. 4 schematically shows an overview of a Nearest neighbor (Nearest-neighbor) method used in step S11 of fig. 3.

Detailed Description

Minimizing the waiting time in the case of spindle supply by targeted placement of the tools in the magazine during the production of a predefined set of one or more types of workpieces is a fundamental optimization criterion.

The initial case-represented by step S1-is typically a rack library (which may also be very full) that is populated with tools. It is possible to apply a heuristic from the patent application "zuorrdnen von Werkzeugen zu Pl ä tzen in einem werkzeugmazin (allocating tools to spaces in the tool library)" with the same priority (Zeitrang) in order to obtain a first solution or target allocation allowed for the tools in the library.

The maximum duration of one cycle (pick or put, mid-stroke, and take) may be calculated. An operation or work step having a production/manufacturing time shorter than the maximum cycle time is said to be critical. Those tools that must be retrieved or taken in the rack magazine during critical operations are referred to as critical tools. The remaining tools are referred to as non-critical tools.

However, the mentioned heuristics are only optimized with respect to latency. In this case, no later reclassification of the tools is considered. However, non-critical tools should be placed as far as possible onto their initial space in order to minimize reclassification sort times. The remaining tools to be placed are therefore inserted into the library meaningfully by means of a method from the patent application "Verfahren zur recohnergestltzten Optimiering Bellegung von Magazinpl ä tzen mit Werkzeugen (method for computer-aided optimization of the occupation of the library space by the tools)" with the same priority. This results in an allowed, but not necessarily optimal solution or target assignment of the tool, which takes into account the waiting time on the one hand and the subsequent reclassification on the other hand.

The calculation of the optimal solution or target assignment is performed in step S2. Another optimization criterion, according to the present invention, is to place as many tools as possible on or near the "old" or previously occupied library space. Furthermore, the optimization should be carried out such that the preferred space is selected as much as possible according to the spatial hierarchy.

Thus, optimization of the tool's occupation of library space should be performed such that the tool is placed on library space that is near the library space previously occupied by the tool, and spatial hierarchy is considered herein. In other words, the permissible space allocation for all tools should be determined such that the total waiting time in the case of spindle supply during production is minimized and the tools are placed as far as possible on a preferred space which is located in the vicinity of the original space or the predecessor library space of the tools.

Thereafter, in step S3, the tool is shifted or reclassified in the rack magazine. This cannot be performed during peak hours (i.e. during ongoing production) and thus leads to downtime of the machine tool.

A special case of the optimization method is linear optimization. The linear optimization involves optimizing a linear objective function over a set bounded by linear equations and inequalities. Which is the basis of a solution approach to (mixed) integer linear optimization. The so-called Solver (Solver) is a general term for a specific data computer program that can solve mathematical problems digitally. In connection with MILP (mixed integer linear programming or mixed integer linear programming), standard solvers such as CPLEX, Scip, Gurobi, Xpress can be used for IP programs (integer optimization models).

An example is described below in which the tool-to-library space occupation within at least one tool library for a machine tool is optimized in a computer-aided manner by means of a MILP model (mixed integer linear programming), with the tool-to-library space occupation making it possible to produce one or more workpieces of one workpiece type.

The following designations apply in the MILP expression method (Formulierung):

inputting parameters:

Lset of all library spaces

TSet of all tools

T _l Set of allowed tools for space l

When the tool t is located on the space l, the spaceAndthe coverage ratio of the space in between,。

Wcollection of workpieces

Op _w The sequence of operations or work steps to be performed by the machine tool in the case of the workpiece type w, i.e.。

quantity _w Number of pieces to be produced of workpiece w

prodTime ⁱ _w Opⁱ _wDuration of (2)

t ⁱ _w Opⁱ _wIn the tool

CritOp _w Set of operations in the case of a workpiece w, after which a waiting time (critical operation) may occur

CSet of predecessor/successor tools (t, t') for an operation, after which a latency (critical tool) may occur.

putTime _t,l Time for retrieving tool t from providing space to space l

getTime _t,l Time for taking tool t from space l to providing space

moveTime _ll, For passing from space l₁To the space l₂The time of the idle stroke.

toolMoveTime ^t _l1,l2 For removing tool t from space l₁Is transported to the space l₂Time of (d).

PreferenceToolLocation _t,l A positive number describing a preference or rating for placing tool t on space i. A small value indicates a low preference and a large value indicates a high preference.

weightWaitingTimeThe weight of the waiting time in the objective function or in the optimization case.

weightNearestLocationWeighting of priorities in an objective function or in an optimized case such that non-critical tools are placed near their original space

weightNearestLocationCriticalToolsThe weighting of the priorities in the objective function or in the optimization case, so that the critical tool is placed near its original space.

weightHierarchyThe weighting of the priorities in the objective function or in the case of optimization, is such that the tool is placed on the preferred space (with respect to a given hierarchy).

Variables are as follows:

setup _t,l space assignment of tool t to space l (value 1 if the tool is assigned to the space, otherwise 0.)

waitingTime ⁱ _w Non-negative waiting times occurring after operation i in the case of workpieces w

h _t1,t2,l1,l2 Auxiliary variables, if tool t₁Is located in space l₁Upper and lower tools t₂Is located in space l₂And if so, the auxiliary variable takes the value 1. Otherwise, the variable is set to a value of 0.

The problem can be expressed as the following integer linear program using this notation.

Minimization function:

multiple objective criteria can be optimized simultaneously by an objective function consisting of multiple weight components. These target criteria are controlled by weight parameters provided as inputs or inputs. The main criterion, which can be weighted via the parameter weightWaitingTime ≧ 0, is still the minimization of latency.

The new tool occupation calculated by optimization must be physically generated in the machine by retrofitting. During this time, the machine may stop. The improvement is therefore that the tool t is placed as far as possible in the old or original space l by optimization^old _tNearby. As a distance measure, a method for transforming a tool t from an original space l may be used^old _tTime of transportation to new space l. Due to the key toolLatency may be incurred, so reductions in latency are prioritized for critical tools before placement near the original space. The non-critical tools should be placed as close as possible to their original space in order to minimize the refitting time in the case of immediate refitting. This can be via parametersweightNearestLocationCriticalTools≧ 0 for key tool or viaweightNearestLocation≧ 0 is controlled for non-critical tools. In general, the weights areweightNearestLocationIs selected to be significantly greater than the weightweightNearestLocationCriticalT ools. Furthermore, the tool should be placed as much as possible on the space for which it is preferred (with respect to its level in the spatial hierarchy). The weights in the objective function may be via parametersweightHierarchyIs controlled to be more than or equal to 0.

Constraint conditions are as follows:

(1) each tool must be assigned a library space.

(2) No library space is allowed to be allocated multiple times.

(3) No tools are allowed on a library space that are not allowed for that space.

(4) For tool pairIf t is₁At l₁Upper and t₂At l₂In the above, thenExactly 1.

(5) If operation Opⁱ _wThe waiting time is shorter than the duration required for the retrieval of the magazine for the preceding tool, the intermediate travel to the next tool and the provision of the next tool.

For allWhereinThe method is applicable to:

for allWhereinThe method is applicable to:

(6) the space covered by one tool is not allowed to be occupied by the tool and two tools are not allowed to collide.

(7) The limit of the variable is set by the variable,

variable h_t1,t2,l1,l2≧ 0 is a binary variable. This additional information may be handed over to a Solver (Solver). However, it is advantageous to set this additional information as a continuous variable.

And (3) model reduction:

the set of constraints (6) for taking into account the space requirements of the tool comprises a number of redundant inequalities. For many library space pairsThese inequalities are always satisfied because the two library spaces are far apart. It is sufficient to consider a space pair in which there is a tool pair that can be stored on the space and conflict. If no such tool pair exists, the inequality has no limiting feature and may be omitted.

Maximum load weight or load per stock column:

furthermore, the maximum load weight per bank column can be taken into account by adding additional constraintsmaxWeightMag(i)Is more than or equal to 0. Furthermore, M is the number of columns of the library andMag(i)is a collection of library spaces in column i,i=1,…,M. For each toolAnd in addition to providing its weighttoolweight(t). Thus, the limitation can be expressed as follows:

the controller of the machine tool provides different types of management of the rack magazine. A possible type is a partial spatial model, for example in a Sinumerik controller. The partial space model enables partial occupation of library space by the tool. One particular form of partial space model is a half space model.

One feature of the half-space model is that the tool need not be symmetrical. A tool requires two half-spaces up and down or left and left, respectively (depending on the manner of viewing). While another tool requires two half-spaces upwards and three half-spaces downwards or to the left and right (depending on the way of viewing). Both tools overlap the adjacent space, however no conflict occurs there, since they only cover the top or bottom or left or right half-space, respectively.

In optimizing the occupancy of the library space, partial/half space may be considered, with the goal that no partial/half space is covered by multiple tools.

The result from steps S1 and S2 is an optimized occupation of library space by the tool, wherein the duration of the entire wait time is minimized.

In a next step S3, the goal is to determine a transfer list WL with which the critical tool can be moved to its target space or at least to the library space, which improves the total waiting time in case of spindle supply. Non-critical tools should remain as long as possible in their old space.

The determination of the transition list is performed in a number of steps:

in step S11 in fig. 3, the nearest neighbor method is first invoked, which attempts to perform a tool transfer with a critical tool. If necessary, the disturbing tool in the target space or its neighboring space is moved to the spare space. The tool transfer whose current library space has the minimum free travel time to the last accessed library space is selected as the next tool transfer.

It may not be possible that all critical tools can be moved onto their target space. Therefore, an attempt is made to move these critical tools onto another library space, respectively, in step S12, so that the total latency is further reduced.

In step S11, a method is first needed to be able to implement a single tool transfer of a critical tool onto a target space that may be occupied, the single tool transfer taking into account space limitations. The tool that should be moved is referred to as transfer tool in the following. The function Werkzeugtransfer (Transferwerkzeug, Zielplatz) checks: whether a given transfer tool can be moved to its target library space. It may be necessary to first clear other tools for this purpose in order to empty the target library space. The set of tools to be cleaned is denoted by w (zielplatz).

Direct transfer finds free space for a transfer tool that can be transported directly onto the space without violating space constraints and without having to move other tools in the library. If this is possible, the transfer is performed immediately. Otherwise, an indirect transfer is attempted. Here, a library space is sought that can be emptied for the tool by direct transfer of one or more tools in the library. The direct transfer of the other tools is performed first, after which the transfer tool is moved. If neither direct nor indirect transfer is possible, then no transfer is performed for the tool. Fig. 4 provides an overview of the nearest neighbor method into which the function werkzeugfer (Zielplatz) is embedded.

The goal of this approach is to integrate T the set of critical tools, if possible_transferTransfer to a predetermined target space. This method is the nearest neighbor method, which attempts to always carry out a transfer in the respective next step for which the empty travel time of the library appliance from the current space to the library space as the next vehicle to be transported is minimal.

The input IN of the method is the set of key tools, their associated target spaces and the last accessed space of the library operating device.

From T_transferIs sorted in step S21 according to the rising empty travel time from the last accessed space of the library device to the corresponding library space of the tool. In step S22, an attempt is made to use the function werkzeugrifer (Zielplatz) for the resulting transfer list (T)_transfer) The first possible tool of (1) performs a tool transfer. If this is not possible, the method ends, denoted by E. Otherwise, the tool to be transferred is fixed on its target space and sorted from the list T in step S23_transferIs deleted. If the tool is fixed on its target space, the tool is no longer allowed to be removed from the space during the method. Now, the library device is on the target space of the tool being migrated, and the list T is realigned_transferSort and try the transfer tool again until the list T can no longer be transferred_transferTool or T in_transferIs empty. In the latter case, the entire method terminates, also denoted E, because all critical tools can be transported to their target library space. If T is_transferNot empty, then an attempt is made in a subsequent step S12 of FIG. 3 to move the key tool that has not yet been transferred onto the library space, which further improves the overall latency as compared to the current library space footprint.

Step S12 proceeds similarly to step S11. The input is a collection of all key tools and has not been transferred yetThe key tools of the associated target space, and the last accessed space of the library device. Further, the current bank occupation after step S11 is required. From T_transferAgain according to the rising empty travel time from the last accessed space to the tool's corresponding library space. The first tools are extracted from the list (and deleted from the list), respectively. Attempts are made to move tools onto the library space by means of the function Werkzeugtransfer (Zielplatz), which further reduces the total latency compared to the current library footprint. To this end, the potential target library spaces for the tools to be transferred are ordered according to a rising improvement in total latency. To calculate the improvement in the total waiting time, all critical tools (except the tool to be transferred) are fixed for a short time. Only the possible target library space for which no critical tool has to be shifted is therefore considered for the transfer tool. The move of the transfer tool to one of the library spaces in the list is attempted in sequence by means of the function Werkzeugtransfer (Zielplatz). If this is not possible for any library space or if the list of possible library spaces is empty, then Slave Liste (T)_transfer) The next tool is extracted. The transfer is performed for the first possible space from the ordered list of library spaces, thereby improving overall latency as compared to current library occupancy. The library occupancy is updated and the migration tool is fixed on its new space. Then, Liste (T) is newly paired_transfer) And (6) sorting. The method terminates when the list of key tools is empty.

The method described above can additionally be combined with the method already proposed in patent application PCT/EP 2018/074999. As described in this patent application, a portion of the critical tool may be transferred to its target space in advance. From the start and target allocation, a set of tool transfers to be executed, which are each composed of a tool and a target space, and their priority relationships are first determined. In order to calculate the optimal sequence of tool transfers without (preferential) loops, an asymmetric TSP (traveling salesman problem) is described, which is solved by means of the mixed integer linear program described therein. The critical tools in the priority loop can then be transferred immediately using the method according to the invention. The calculation time can be reduced.

Although the invention is further illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variants can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

The implementation of the processes or method flows described above can be performed according to instructions that are present on a computer-readable storage medium or in a volatile computer memory (hereinafter generally referred to as computer-readable memory). The computer-readable memory is, for example, volatile memory, such as buffers, buffers or RAM, and non-volatile memory, such as a removable data carrier, a hard disk, etc.

The functions or steps described above may be present herein in/on the computer readable memory in the form of at least one set of instructions. The functions or steps are not bound to any particular instruction set or to any particular form of instruction set or to any particular storage medium or to any particular processor or to any particular implementation, but may be implemented by software, firmware, microcode, hardware, processors, integrated circuits, etc., operating alone or in any combination. Here, different processing strategies may be used, such as serial processing by a single processor or multi-processing or multi-tasking or parallel processing, etc.

The instructions may reside in local memory, but it is also possible to reside on a remote system and access the remote system via a network.

Within the context of the present invention, "computer-assisted" is understood to mean, for example, the implementation of a method, in which, in particular, a processor implements at least one method step of the method.

The terms "processor", "central signal processing", "control unit" or "data evaluation device" as used herein include the broadest processing device, i.e., for example, a server, general purpose processor, graphics processor, digital signal processor, Application Specific Integrated Circuit (ASIC), programmable logic circuitry, such as an FPGA, discrete analog or digital circuitry, and any combination thereof, including all other processing devices known to those skilled in the art or developed in the future. A processor may here be made up of one or more devices or apparatuses or units. If the processor is comprised of multiple devices, the devices may be designed or configured to process or execute instructions in parallel or sequentially. Within the context of the present invention, a "Memory unit" may be understood, for example, as a Memory in the form of a working Memory (Random-Access Memory, RAM) or a hard disk.