Production system

Abstract

To provide a production system that can achieve optimum production by considering a tool cost and a labor cost.SOLUTION: A production system 1 comprises: production facilities 2 which process a workpiece W using a tool T under an operation or management of a worker; and a command device 6 which commands operation of the production facilities 2 to the production facilities 2. There is a relation that the higher machining efficiency of the tool T is, the shorter a tact time T_tact required for production of one workpiece W becomes. There is a relation that the higher the machining efficiency is, the higher a tool cost Ctool due to tool modification or tool replacement becomes. A labor cost Cperson is set depending on working hours of the worker. The command device 6 includes: a tact time determination unit 12 which determines the tact time T_tact so as to lower a total cost Ctotal including the tool cost Ctool and the labor cost Cperson; and a command unit 13 which commands production in the determined tact time T_tact to the production facilities 2.SELECTED DRAWING: Figure 11

Description

Technical Field

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[0001] The present invention relates to a production system.

Background Art

[0002] Patent Document 1 describes determining the processing assigned to a plurality of multi - task machine tools according to the operating time of the multi - task machine tools, the production quantity of the workpiece, and the processing time per unit quantity. By thus determining the processing assigned to a plurality of multi - task machine tools according to the situation, it is possible to cope with increases and decreases in the production quantity.

[0003] Patent Document 2 describes a cyber - physical production system having a production line that can be operated by autonomously correcting production command values so as to satisfy production conditions. This production system determines the operating conditions of the production line so that, for example, the cost obtained by summing the production costs generated by grinding processing, heat treatment, and inspection processing satisfies the reference cost. As a specific example, as the tool cost included in the production cost, there are mentioned the replacement cost and the regeneration cost of components of a grinding machine, a heat treatment furnace, and an inspection machine (for example, a grinding wheel carriage, a furnace, an inspection camera, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in addition to equipment costs, there are also labor costs for workers. Generally, when workpieces are processed at high efficiency in production equipment, the processing load on the tools increases, and the tools wear out faster. Therefore, processing workpieces at high efficiency increases tool costs. On the other hand, if the processing efficiency is low, the time required to process one workpiece increases. Therefore, it takes time to process the target production quantity of workpieces set in the production plan. As a result, depending on the worker's work style, the worker's working hours may increase, and labor costs may rise.

[0006] This invention has been made in view of the above problems, and aims to provide a production system that can achieve optimal production while taking into account tool costs and labor costs. [Means for solving the problem]

[0007] One aspect of the present invention is a production facility configured to process a workpiece using a tool through the operation or management of an operator, A command device that issues commands to the production equipment regarding the operation of the production equipment, Equipped with, The higher the machining efficiency of the tool, the shorter the cycle time required to produce one workpiece; the higher the machining efficiency, the higher the tool cost associated with tool modification or tool change; and the labor cost is set according to the working hours of the operator. The aforementioned cycle time is configured to be set within a range from a predetermined minimum time to a predetermined maximum time that satisfies the target quality of the workpiece. The command device is Based on the target production quantity of the workpiece and the target completion time for producing the target production quantity of the workpiece, a target cycle time is calculated, which is the target value of the cycle time required to produce the target production quantity of the workpiece by the target completion time. Based on the target cycle time, A cycle time determination unit that determines the cycle time in such a way as to reduce the total cost, including the tool cost and the labor cost, A control unit that instructs the production equipment to produce within the determined cycle time, It is part of a production system that includes these features. Another aspect of the present invention is a production facility configured to process a workpiece using tools through the operation or management of an operator, A command device that issues commands to the production equipment regarding the operation of the production equipment, Equipped with, The higher the machining efficiency of the tool, the shorter the cycle time required to produce one workpiece; the higher the machining efficiency, the higher the tool cost associated with tool modification or tool change; and the labor cost is set according to the working hours of the operator. Multiple production facilities perform machining processes, pre-machining processes, and post-machining processes, respectively. The production equipment that performs the machining process performs tool modification or tool change, and includes the unit machining time required for the machining process of one workpiece in the command data of the machining conditions. The command device is An acquisition unit that acquires the relationship between the cycle time and the unit processing time by actually or in simulation executing each process by the aforementioned production equipment, A cycle time determination unit that determines the cycle time in such a way as to reduce the total cost, including the tool cost and the labor cost, A command unit that commands the production equipment performing the machining to perform the machining, to produce within the determined cycle time, the cycle time corresponding to the determined cycle time, It is part of a production system that includes these features. Another aspect of the present invention is a production facility configured to process a workpiece using tools through the operation or management of an operator, A command device that issues commands to the production equipment regarding the operation of the production equipment, Equipped with, The cycle time required to produce one of the workpieces includes a first time required for machining the workpiece using the tool, and a second time required for tool adjustment or tool change. The higher the machining efficiency of the tool, the shorter the first time becomes, while the second time per workpiece produced becomes longer. Furthermore, the reduction in the first time due to the increase in processing efficiency is greater than the extension in the second time, so there is a relationship in which the higher the processing efficiency, the shorter the cycle time. The higher the machining efficiency, the higher the tool cost associated with tool modification or tool replacement, and the labor cost is set according to the worker's working hours. The command device is A cycle time determination unit that determines the cycle time in such a way as to reduce the total cost, including the tool cost and the labor cost, A control unit that instructs the production equipment to produce within the determined cycle time, It is part of a production system that includes these features.

Advantages of the Invention

[0008] According to the above aspect, when the machining efficiency is increased, the load on the tool increases, so the tool cost associated with tool correction or tool replacement increases. When the machining efficiency is increased, the tact time required for the production of one workpiece is shortened, so the working hours of the operator are shortened and the labor cost does not increase. On the other hand, when the machining efficiency is decreased, the tact time required for the production of one workpiece becomes longer, so the working hours of the operator become longer and the labor cost may increase. However, when the machining efficiency is decreased, the load on the tool decreases, so the tool cost associated with tool correction or tool replacement decreases. Thus, the tool cost and the labor cost have an inverse relationship with respect to the machining efficiency.

[0009] Therefore, the cycle time determination unit, which constitutes the control device, uses the total cost, including tool costs and labor costs, to determine a cycle time that minimizes the total cost. The control unit then instructs the production equipment to process the workpiece within the determined cycle time. Consequently, workpieces can be processed with a processing efficiency that minimizes the total cost, thereby achieving optimal production.

[0010] As described above, according to the above embodiment, it is possible to provide a production system that can achieve optimal production while taking into account tool costs and labor costs. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram showing the configuration of the production system in Embodiment 1. [Figure 2] This figure shows a grinding machine as an example of a processing device that makes up a production system. [Figure 3] This is a flowchart showing the machining process (grinding process) on a grinding machine. [Figure 4] This figure shows the change in the X-axis position of the grinding wheel during machining (grinding) in a grinding machine. [Figure 5] This is a diagram illustrating the tool adjustment interval for a machining device. [Figure 6] This diagram illustrates cycle time and unit processing time according to processing efficiency. [Figure 7] This figure shows the tool costs, labor costs, and total costs over time. [Figure 8] This diagram shows the processing performed by the command device that constitutes the production system. [Figure 9] This diagram shows the data used by the command device when generating command information. [Figure 10] This figure shows another example of the data used by the command device when generating command information. [Figure 11]This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 12] This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 13] This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 14] This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 15] This flowchart shows the processing performed by the command device that constitutes the production system in Embodiment 2. [Figure 16] This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 17] This diagram illustrates the determination of machining efficiency in Embodiment 3, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 18] This is a flowchart showing the processing performed by the command device that constitutes the production system in Embodiment 4. [Figure 19] This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 20] This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 21] This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Figure 22]This diagram illustrates the determination of machining efficiency, showing tool costs, labor costs, total costs, and the determined object as time progresses from the present. [Modes for carrying out the invention]

[0012] (Embodiment 1) 1. Configuration of Production System 1 The configuration of production system 1 will be explained with reference to Figure 1. Production system 1 comprises a plurality of production equipment 2, 3, and 4, a control device 5, and a command device 6. The plurality of production equipment 2, 3, and 4 are, for example, production equipment for producing workpieces W, and sequentially perform processing on workpieces W.

[0013] Production equipment 2 is a processing device that performs machining on a workpiece W. Production equipment 2 is a processing device (machine tool) that performs removal processing (cutting and grinding), such as a lathe, machining center, gear cutting device, or grinding machine. Therefore, production equipment 2, being a processing device, is configured to process the workpiece W using a tool T through the operation or management of an operator. The tool T is a cutting tool or a grinding wheel, etc.

[0014] Operator operations refer to actions such as operating the operation screen or buttons on production equipment 2. Operations may require individual operation of each workpiece W, or a single operation may suffice for a series of operations on multiple workpieces W. The latter is, for example, the operation of the button to start continuous production. Operator management includes confirming the normal operation of production equipment 2 and replenishing auxiliary materials. However, there is no need to specifically distinguish between operation and management, and "by operator operation or management" means "by the operator's involvement."

[0015] Production equipment 3 is equipment that performs pre-processing for production equipment 2, which is a processing device. In other words, production equipment 3 generates the material for the workpiece W of production equipment 2, which is a processing device. Production equipment 3 that performs pre-processing includes, for example, processing devices that perform removal processes such as lathes, machining centers, and gear cutting devices, processing devices that perform forging and casting, heat treatment equipment that performs heat treatment, surface treatment equipment, and laser processing equipment.

[0016] Production equipment 4 performs post-processing on the workpiece W processed by production equipment 2, which is a processing device. As post-processing, production equipment 4 performs, for example, finishing work, inspection, etc. Production equipment 2, 3, and 4 may each consist of one unit or multiple units. Production equipment 3 and 4 may be configured to operate through operator operation or management, or they may be configured to operate without operator operation or management.

[0017] Production equipment 2 to 4 are equipped with at least a drive unit and a detection unit, the drive unit is driven based on control data, and the detection unit obtains detection data. In addition, each of production equipment 2 to 4 may be equipped with a calculation unit that calculates the state of each production equipment 2 to 4 based on at least one of the control data of the drive unit, the drive data of the drive unit, and the detection data of the detection unit.

[0018] For example, the computing unit performs at least one of the following based on control data, drive data, and detection data: estimating the quality of the workpiece W, estimating the timing of tool adjustments and tool changes, generating operating status data for each of the production equipment 2-4, and estimating the cause of abnormalities for each of the production equipment 2-4. The calculations performed by the computing unit may be performed in real time for each production process of production equipment 2-4, or not in real time. The computing unit may also be an embedded system of production equipment 2-4, or a separate unit from production equipment 2-4, such as an edge computer or cloud computer. Production equipment 2-4 may also be omitted from the computing unit.

[0019] The control device 5 stores the production plan. The control device 5 may also have a function to generate the production plan. The production plan includes management data such as the production date (delivery date) for each workpiece W, process information for workpiece W, and the execution schedule for each process. The management data is entered into the control device 5 by the administrator.

[0020] The command device 6 issues commands to each of the production equipment 2 to 4 regarding their respective operations. Specifically, the command device 6 acquires equipment data from each of the production equipment 2 to 4. The equipment data is data related to the operation of the production equipment 2 to 4 and includes at least one of the following: control data, drive data, detection data, calculation data, and production completion data for individual workpieces W. Furthermore, the command device 6 acquires management data from the management device 5.

[0021] The command device 6 generates command data for the operating conditions of each of the production equipment 2-4 based on equipment data and management data, and outputs the command data to each of the production equipment 2-4. In particular, the command device 6 performs calculations in real time while production equipment 2-4 is operating and issues commands to production equipment 2-4 in real time. In other words, the command device 6 can function as a device for realizing processing in the virtual space in a cyber-physical production system (CPPS). In this case, the command device 6 can execute the operations of production equipment 2-4 in the real world in real time in the virtual space, and use the processing results to control the operations of production equipment 2-4 in the real world in real time. The command device 6 also generates aggregated data by aggregating the equipment data of production equipment 2-4 and outputs it to the management device 5.

[0022] The command device 6 includes an acquisition unit 11, a cycle time determination unit 12, a command unit 13, and a summary data output unit 14 to realize some of the above functions. The acquisition unit 11 acquires equipment data from each of the production equipment 2 to 4. The cycle time determination unit 12 determines the cycle time T_tact required to produce one workpiece W based on the equipment data acquired by the acquisition unit 11 and the management data acquired from the management device 5. In particular, in this embodiment, the cycle time determination unit 12 determines the cycle time T_tact by considering the total cost Ctotal, which includes tool costs Ctool and labor costs Cperson. In addition to tool costs Ctool and labor costs Cperson, the total cost Ctotal may also include equipment operating costs necessary for the operation of production equipment 2 to 4, such as electricity costs.

[0023] The command unit 13 commands the production equipment 2, which constitutes the processing apparatus, to produce the workpiece W at the takt time T_tact determined by the takt time determination unit 12. The aggregated data output unit 14 aggregates data related to the operation of production equipment 2 to 4 to generate aggregated data and outputs the aggregated data to the management device 5. The aggregated data includes, for example, at least one of the following as operational results: the start and end times of production of the workpiece W, equipment downtime, control data during production, drive data, detection data, the number of tool adjustments and tool changes, and the execution times of tool adjustments and tool changes.

[0024] 2. Configuration of Production Facility 2 An example of the configuration of the production equipment 2, which is a processing device, will be explained with reference to Figure 2. In this embodiment, the production equipment 2 is an example of a cylindrical grinding machine. In Figure 2, the production equipment 2 is an example of a grinding wheel traverse type cylindrical grinding machine, but a table traverse type cylindrical grinding machine can be used, or a grinding machine with a different configuration can be used.

[0025] The grinding machine, which is part of production equipment 2, comprises a bed 21, a workpiece support base 22, a traverse base 23, and a grinding wheel base 24. The workpiece support base 22 is provided on the upper surface of the bed 21 and consists, for example, a headstock that supports one end of an axial workpiece W and a tailstock that supports the other end. The headstock and tailstock that make up the workpiece support base 22 allow the workpiece W to rotate.

[0026] The traverse base 23 is configured to be movable on the upper surface of the bed 21 in a direction parallel to the axial direction of the workpiece W (Z-axis direction). The grinding wheel base 24 is configured to be movable on the upper surface of the traverse base 23 in a direction approaching or moving away from the workpiece W (X-axis direction). The grinding wheel base 24 also rotates the grinding wheel, which is the tool T. The grinding machine, as production equipment 2, grinds the workpiece W by moving the workpiece W and the grinding wheel (tool T) relative to each other.

[0027] 3. Processing at Production Facility 2 The machining process using the grinding machine, which is production equipment 2 shown in Figure 2, i.e., the grinding process, will be explained with reference to Figures 3 and 4. In Figure 4, (a) and (b) have different machining efficiencies in at least some of the machining processes. Machining efficiency corresponds to the volume of workpiece W removed per unit time.

[0028] Figure 4(a) shows the case where machining efficiency is high, and in particular, the moving speed of the grinding wheel, which is the tool T, in the rough grinding process S3 is fast. Figure 4(b) shows the case where machining efficiency is low, and in particular, the moving speed of the grinding wheel, which is the tool T, in the rough grinding process S3 is slow. In (a) and (b), the other processes are the same. In this embodiment, only the rough grinding process S3 is given as an example of a process that increases machining efficiency, but other processes can also be targeted for changing machining efficiency.

[0029] The machining process (grinding process) involves a rapid traverse advance process S1 (t0→t1) to bring the grinding wheel, which is the tool T, closer to the workpiece W. In the rapid traverse advance process S1, the X-axis position of the grinding wheel moves rapidly from X0 to X1. When the X-axis position of the grinding wheel reaches X1 in the rapid traverse advance process S1, the aerodynamic grinding process S2 is performed (t1→t2). In the aerodynamic grinding process S2, the movement speed of the grinding wheel is made slower than in the rapid traverse advance process S1, bringing the grinding wheel closer to the workpiece W.

[0030] Next, in the aerodynamic grinding process S2, when the workpiece W reaches a predetermined aerodynamic dimension (when the X-axis position of the grinding wheel reaches X2), the rough grinding process S3 is performed (t2→t3, t2→t13). In the rough grinding process S3, the movement speed of the grinding wheel is made slower than in the aerodynamic grinding process S2, and after the grinding wheel comes into contact with the workpiece W, rough grinding (also called rough machining) is performed. As shown in Figure 4(a), when the machining efficiency is high, the time of the rough grinding process S3 is shortened, and as shown in Figure 4(b), when the machining efficiency is low, the time of the rough grinding process S3 is lengthened.

[0031] Next, in the rough grinding process S3, when the workpiece W reaches a predetermined rough grinding dimension (when the X-axis position of the grinding wheel reaches X3), the fine grinding process S4 is performed (t3→t4, t13→t14). In the fine grinding process S4, the movement speed of the grinding wheel is made slower than in the rough grinding process S3, and fine grinding is performed as part of the finishing process.

[0032] Next, in the precision grinding process S4, when the workpiece W reaches a predetermined precision grinding dimension (when the X-axis position of the grinding wheel reaches X4), the micro-grinding process S5 is performed (t4→t5, t14→t15). In the micro-grinding process S5, the movement speed of the grinding wheel is made slower than in the precision grinding process S4, and micro-grinding is performed as an additional part of the finishing process.

[0033] Next, in the micro-grinding process S5, when the workpiece W reaches a predetermined micro-grinding dimension (when the X-axis position of the grinding wheel reaches X5), the spark-out process S6 is performed (t5→t6, t15→t16). In the spark-out process S6, the X-axis positions X5 and X6 of the grinding wheel coincide. After the spark-out process S6 is completed, the rapid traverse retraction process S7 is performed (t6→t7, t16→t17).

[0034] As shown in Figure 4(a), the higher the machining efficiency, the shorter the time required to machine a single workpiece W (t0→t7). On the other hand, as shown in Figure 4(b), the lower the machining efficiency, the longer the time required to machine a single workpiece W (t0→t17).

[0035] 4. Explanation regarding tool modification The grinding wheel, which is a tool T that makes up the grinding machine, production equipment 2 shown in Figure 2, becomes worn or rough on the surface of the grinding wheel due to repeated grinding of the workpiece W. Deterioration of the surface condition of the tool T, such as the grinding wheel, causes a decrease in the machining accuracy of the workpiece W, such as deterioration of the surface properties of the workpiece W and the formation of a processed altered layer on the workpiece W.

[0036] Therefore, in order to improve the surface condition of the grinding wheel, which is the tool T, truing and dressing are performed as modifications to the tool T. Truing is a reshaping process, in which the grinding wheel is reshaped to the desired form when it is worn down by grinding. Dressing is a sharpening process, in which the amount of abrasive grain protrusion is adjusted and the cutting edges of the abrasive grains are created. Dressing is a process to correct defects such as clogged or chipped grains. Note that truing and dressing are sometimes performed without any particular distinction.

[0037] The process related to tool correction will be explained with reference to Figure 5. Figure 5 shows the change in the tool correction index value with respect to the production quantity of workpiece W when the machining efficiency is set to three types: "high," "medium," and "low." The tool correction index value increases as machining of the workpiece W is performed and decreases to its minimum value when tool correction is performed. Tool correction is performed when the tool correction index value reaches Th.

[0038] The tool correction index value can be, for example, a value corresponding to the surface roughness of the workpiece W. Generally, in grinding operations using a grinding wheel with superabrasive grains such as CBN abrasive grains, the surface roughness of the workpiece W increases with increasing production quantity of the workpiece W. In this case, the tool correction index value can be the surface roughness itself. Also, in grinding operations using a conventional grinding wheel with alumina-based abrasive grains, the surface roughness of the workpiece W decreases with increasing production quantity of the workpiece W. In this case, the tool correction index value can be the reciprocal of the surface roughness. As described above, the tool correction index value can be set to any value according to the type of grinding operation. In this embodiment, the tool correction index value is set to increase with increasing production quantity of the workpiece W, but it can also be set to decrease with increasing production quantity of the workpiece W.

[0039] As explained in Figures 3 and 4, in machining equipment such as grinders, lathes, and machining centers that perform cutting or grinding operations on a workpiece W using a tool T, the machining efficiency can be changed. Machining efficiency, as mentioned above, corresponds to the volume of material removed from the workpiece W per unit time. In other words, the higher the machining efficiency, the shorter the machining time for the workpiece W, and the lower the machining efficiency, the longer the machining time for the workpiece W. Furthermore, the higher the machining efficiency, the worse the machining accuracy of the workpiece W, while the lower the machining efficiency, the better the machining accuracy of the workpiece W. Examples of machining accuracy include surface roughness.

[0040] As shown in Figure 5, when the machining efficiency, indicated by the dashed line, is "high," the frequency of tool adjustments is high relative to the production quantity of workpieces W. The interval for tool adjustments when the machining efficiency is "high" is ΔInt_hi. When the machining efficiency, indicated by the dashed line, is "low," the frequency of tool adjustments is low relative to the production quantity of workpieces W. The interval for tool adjustments when the machining efficiency is "low" is ΔInt_low. ΔInt_low is a longer time than ΔInt_hi.

[0041] When the machining efficiency, indicated by the dashed line, is "medium," the frequency of tool adjustments relative to the production quantity of workpiece W is lower than in the "high" case and higher than in the "low" case. The tool adjustment interval when the machining efficiency is "medium" is ΔInt_mid. ΔInt_mid is longer than ΔInt_hi and shorter than ΔInt_low. Thus, the tool adjustment interval is determined based on the machining efficiency.

[0042] Furthermore, for a tool T such as a grinding wheel, the number of times tool adjustments can be performed is set to a predetermined number. When a tool T has reached the predetermined number of adjustments, it becomes subject to tool replacement. Therefore, the shorter the interval between tool adjustments, the shorter the interval between tool replacements, and the longer the interval between tool adjustments, the longer the interval between tool replacements. In this way, the interval between tool replacements is determined based on machining efficiency.

[0043] 5. Explanation of tact time T_tact The cycle time T_tact is the time required to produce one workpiece W. More specifically, the cycle time T_tact is the total time required to produce n workpieces W divided by n. The total time required to produce n workpieces W includes (1) the time required for machining the n workpieces W, in addition to (2) the time required for loading and unloading the n workpieces W, (3) the time required for modifying and replacing tools T during the production of n workpieces W, and (4) the time during which production equipment 2-4 is stopped during the production of n workpieces W.

[0044] Furthermore, the higher the machining efficiency, the shorter the time required to machine one workpiece W, and the lower the machining efficiency, the longer the time required to machine one workpiece W. On the other hand, the higher the machining efficiency, the shorter the interval between tool adjustments and tool changes, resulting in a longer time required for tool adjustments and tool changes in the production of one workpiece W, and the lower the machining efficiency, the shorter the time required for tool adjustments and tool changes in the production of one workpiece W.

[0045] Generally, in the production of a single workpiece W, the time reduction required for machining due to increased machining efficiency is greater than the time increase required for tool modification or tool change due to increased machining efficiency. Therefore, there is a relationship where the cycle time T_tact decreases as machining efficiency increases, and conversely, the cycle time T_tact increases as machining efficiency decreases.

[0046] As shown in Figure 6, when the machining efficiency is "high," the cycle time T_tact becomes Ttact_min, for example, 80 seconds. When the machining efficiency is "medium," the cycle time T_tact becomes Ttact_mid, for example, 100 seconds. When the machining efficiency is "low," the cycle time T_tact becomes Ttact_max, for example, 120 seconds. In addition, the "unit machining time," which is the time required to machine one workpiece W in each of the "high," "medium," and "low" machining efficiency cases, is Tmc_min (for example, 40 seconds), Tmc_mid (for example, 60 seconds), and Tmc_max (for example, 80 seconds).

[0047] Note that the example times in Figure 6 assume that the time other than the unit machining time within the cycle time T_tact is the same, but in reality, it will vary. However, the variable factors include not only tool adjustments and tool changes, but also downtime of production equipment 2, and are very complex. Therefore, Figure 6 shows results obtained using methods such as actual measurements and simulations.

[0048] 6. Explanation of tool costs (Ctool), labor costs (Cperson), and total costs (Ctotal) The tool cost Ctool, labor cost Cperson, and total cost Ctotal will be explained with reference to Figure 7. The tool cost Ctool corresponds to the amount of tool wear associated with machining. The more frequent the tool adjustments and tool changes, the greater the tool wear. In other words, the tool cost Ctool is the cost associated with tool adjustments or tool changes. Specifically, as shown in Figure 7, the tool cost Ctool increases with the frequency of tool adjustments and tool changes during the continuous production of the workpiece W, and decreases with the frequency of tool adjustments and tool changes.

[0049] Furthermore, the timing of tool adjustments and tool changes varies depending on the machining efficiency. Therefore, the higher the machining efficiency, the higher the tool cost Ctool associated with tool adjustments or tool changes, and the lower the machining efficiency, the lower the tool cost Ctool associated with tool adjustments or tool changes. As shown in Figure 7, the rate of increase in tool cost Ctool over time is in the order of tool cost Ctool1 for high machining efficiency, tool cost Ctool2 for medium machining efficiency, and tool cost Ctool3 for low machining efficiency.

[0050] Furthermore, the labor cost Cperson is set according to the worker's working hours. For example, the worker shown by the solid line in Figure 7 is a worker whose working hours are fixed with a set start time Tw_start and a set end time Tw_fin (fixed time). The labor cost Cperson of this worker is constant from the set start time Tw_start to the set end time Tw_fin (fixed time) during working hours. However, for this worker, after the set end time Tw_fin during working hours, the labor cost Cperson increases as the overtime hours increase.

[0051] Furthermore, some workers have employment arrangements where the labor cost Cperson does not remain constant for extended periods, but rather increases with longer working hours. These workers are essentially part-time employees.

[0052] As shown in Figure 7, the rate of increase in tool costs Ctool1, Ctool2, and Ctool3 over time is greater than the rate of increase in labor costs Cperson over time, within the worker's working hours before the prescribed end time Tw_fin. Furthermore, even after the prescribed end time Tw_fin, within the worker's working hours, the rate of increase in tool costs Ctool1, Ctool2, and Ctool3 over time is greater than the rate of increase in labor costs Cperson over time.

[0053] The total cost Ctotal includes at least the tool cost Ctool and the labor cost Cperson. As shown in Figure 7, the longer the operating time of production equipment 2, the higher the total cost Ctotal. The higher the processing efficiency, the higher the total cost Ctotal. In other words, the time increase rates of the total cost Ctotal, in descending order, are Ctotal1 for high processing efficiency, Ctotal2 for medium processing efficiency, and Ctotal3 for low processing efficiency. Furthermore, after the specified end time Tw_fin, the time increase rates of total costs Ctotal1, Ctotal2, and Ctotal3 are higher than before the specified end time Tw_fin. As mentioned above, the total costs Ctotal, Ctotal1, Ctotal2, and Ctotal3 may also include equipment operating costs necessary for the operation of production equipment 2 to 4, such as electricity costs, in addition to the tool cost Ctool and the labor cost Cperson.

[0054] 7. Processing by the command device 6 The processing of the command device 6 will be explained with reference to Figures 8 and 9. Here, the processing of the command device 6 by a worker from the start to the end of workday will be described. However, the period covered by the processing of the command device 6 may be any period, regardless of the worker's start and end times. For example, the period may include multiple days, such as one week, several weeks, one month, or several months, or it may be a time period from 0:00 to 24:00, or any time period in the morning or afternoon. For example, if workers are on a shift system and production equipment 2 to 4 are operated continuously, the period may be any predetermined period as described above.

[0055] The takt time determination unit 12 of the command device 6 first obtains the target production quantity Ntar of the workpiece W from the control device 5 (S11). The target production quantity Ntar is, for example, the quantity of workpiece W to be produced from the start to the end of work in one day. Next, the takt time determination unit 12 of the command device 6 obtains the prescribed end time Tw_fin from the control device 5, which is one of the target completion times for producing workpiece W of the target production quantity Ntar (S12). The prescribed end time Tw_fin is the prescribed end time of work set for the worker's work style.

[0056] Next, the takt time determination unit 12 of the command device 6 calculates the target takt time Ttar_tact, which is the target value of the takt time T_tact required to produce workpieces W of the target production quantity Ntar by the target completion time, based on the target production quantity Ntar and the target completion time (S13). In this embodiment, since the target completion time is the specified end time Tw_fin, the takt time determination unit 12 of the command device 6 calculates the target takt time Ttar_tact required to produce workpieces W of the target production quantity Ntar by the specified end time Tw_fin. The target takt time Ttar_tact can be obtained, for example, by subtracting the current time Tnow from the specified end time Tw_fin and dividing the subtracted value (Tw_fin-Tnow) by the target production quantity Ntar.

[0057] Next, the takt time determination unit 12 of the command device 6 determines the takt time T_tact based on the target takt time Ttar_tact (S14). Refer to Figure 9 for the determination of the takt time T_tact.

[0058] Here, the cycle time T_tact is configured to be configurable within a range from a predetermined minimum time Ttact_min to a predetermined maximum time Ttact_max. The configurable range of the cycle time T_tact is defined as the range that satisfies the target quality of the workpiece W.

[0059] In this configuration, the cycle time T_tact is selected from three types: a predetermined minimum time Ttact_min, a predetermined maximum time Ttact_max, and a predetermined intermediate time Ttact_mid. As explained in Figure 6, the predetermined minimum time Ttact_min, predetermined maximum time Ttact_max, and predetermined intermediate time Ttact_mid correspond to the cycle time T_tact corresponding to "high," "medium," and "low" machining efficiency, respectively. However, the cycle time T_tact may be set to any number.

[0060] As shown in Figure 9, the takt time determination unit 12 of the command device 6 determines the takt time T_tact in such a way that the total cost Ctotal is lowered if the production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin. The production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin if the target takt time Ttar_tact is equal to or greater than the predetermined shortest time Ttact_min.

[0061] In detail, if the calculated target cycle time Ttar_tact is greater than or equal to the predetermined maximum time Ttact_max, the cycle time T_tact is set to the predetermined maximum time Ttact_max. In this case, the processing efficiency corresponds to "low". Also, if the calculated target cycle time Ttar_tact is shorter than the predetermined maximum time Ttact_max and greater than or equal to the predetermined intermediate time Ttact_mid, the cycle time T_tact is set to the predetermined intermediate time Ttact_mid. In this case, the processing efficiency corresponds to "medium". Also, if the calculated target cycle time Ttar_tact is shorter than the predetermined intermediate time Ttact_mid and greater than or equal to the predetermined minimum time Ttact_min, the cycle time T_tact is set to the predetermined minimum time Ttact_min. In this case, the processing efficiency corresponds to "high".

[0062] Furthermore, the takt time determination unit 12 of the command device 6 determines the takt time T_tact so that production of workpiece W with a target production quantity Ntar cannot be completed after the specified end time Tw_fin. Production of workpiece W with a target production quantity Ntar cannot be completed before the specified end time Tw_fin if the target takt time Ttar_tact is shorter than the predetermined shortest time Ttact_min.

[0063] In detail, if the calculated target cycle time Ttar_tact is shorter than the predetermined shortest time Ttact_min, the cycle time T_tact is set to the predetermined shortest time Ttact_min. In this case, the processing efficiency corresponds to "high".

[0064] As shown in Figure 8, after the takt time determination unit 12 of the command device 6 determines the takt time T_tact (S14), the command unit 13 of the command device 6 issues a command to the production equipment 2 to produce at the determined takt time T_tact (S15). Here, the production equipment 2 is set to include the processing efficiency in the command data of the processing conditions. Therefore, the command information from the command unit 13 is, for example, information such as "high," "medium," or "low," which are processing efficiency, as shown in Figure 9. When the production equipment 2 receives a command from the command unit 13 of the command device 6 regarding the processing efficiency, it produces the workpiece W at the commanded processing efficiency.

[0065] Next, the acquisition unit 11 of the command device 6 acquires processing result information for each workpiece W from the production equipment 2 (S16). The processing result information includes various information from the production equipment 2 regarding the processing of the workpiece W. The processing result information includes, for example, at least one of the following: that one workpiece W has been processed, the estimated quality of the processed workpiece W, the estimated timing of tool correction or tool change, the operating status data of the production equipment 2, and the estimated cause of the abnormality of the production equipment 2. The processing result information may also include control data, drive data, detection data itself, etc., obtained from the production equipment 2.

[0066] Next, the command device 6 determines whether or not production of workpiece W with a target production quantity Ntar has been completed (S17). If production has not been completed (S17: No), the command device 6 repeats the process from S11. In other words, the command device 6 performs the processes S11 to S16 for each workpiece W. Accordingly, the takt time determination unit 12 of the command device 6 sequentially acquires the current target production quantity Ntar and the specified end time Tw_fin as the target completion time each time a workpiece W is processed, and recalculates the target takt time Ttar_tact. For example, if the target production quantity Ntar is changed due to a change in the production plan, the target takt time Ttar_tact is recalculated based on the changed target production quantity Ntar. Then, the takt time determination unit 12 re-determines the takt time T_tact in real time based on the recalculated target takt time Ttar_tact.

[0067] On the other hand, if production of workpiece W with a target production quantity Ntar is completed (S17: Yes), the aggregated data output unit 14 of the command device 6 aggregates data related to multiple workpieces W and outputs the aggregated data to the management device 5 (S18). The aggregated data includes information acquired by the acquisition unit 11, and may also include the takt time T_tact determined by the takt time determination unit 12 and the command information issued by the command unit 13 to the production equipment 2.

[0068] In the above, the command information that the command unit 13 of the command device 6 commands to the production equipment 2 is the processing efficiency. Alternatively, as shown in Figure 10, the command information may also be the unit processing time Tmc_max, Tmc_mid, Tmc_min. In this case, the production equipment 2 includes the unit processing time Tmc_max, Tmc_mid, Tmc_min in the command data for processing conditions. Furthermore, as shown in Figure 6, the command device 6 obtains the relationship between the cycle time Ttact_max, Ttact_mid, Ttact_min and the unit processing time Tmc_max, Tmc_mid, Tmc_min by actually executing each process by the production equipment 2 to 4 or by simulation. The relationship between the cycle time Ttact_max, Ttact_mid, Ttact_min and the unit processing time Tmc_max, Tmc_mid, Tmc_min is as shown in Figure 10. These relationships are the same as in Figure 6.

[0069] Then, the command unit 13 of the command device 6 commands the production equipment 2 to determine the unit processing times Tmc_max, Tmc_mid, and Tmc_min corresponding to the takt time T_tact determined by the takt time determination unit 12. When the production equipment 2 receives a command from the command unit 13 of the command device 6 regarding the unit processing times Tmc_max, Tmc_mid, and Tmc_min, it produces the workpiece W using the commanded unit processing times Tmc_max, Tmc_mid, and Tmc_min.

[0070] 8. Specific processing of the cycle time determination unit 12 The specific processing of the cycle time determination unit 12, that is, the processing of S14 in Figure 8, will be explained with reference to Figures 11 to 14.

[0071] The first example will be explained with reference to Figure 11. The first example is when the production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin, and the target cycle time Ttar_tact is longer than the specified maximum time Ttact_max.

[0072] The white circles in Figure 11 indicate the timing at which production of workpiece W with a target production quantity Ntar is completed on the lines representing tool costs Ctool1, Ctool2, and Ctool3. When machining efficiency is "high," production is completed with ample time remaining until the specified end time Tw_fin. On the other hand, when machining efficiency is "low," production is completed before the specified end time Tw_fin, but very close to it. The white circles on the lines representing tool costs Ctool1, Ctool2, and Ctool3 indicate that machining efficiency increases in the order of "low," "medium," and "high."

[0073] Similarly, on the lines showing the total costs Ctotal1, Ctotal2, and Ctotal3, white circles indicate the timing at which production of workpiece W with a target production quantity Ntar is completed. At each white circle on the lines showing the total costs Ctotal1, Ctotal2, and Ctotal3, the lowest cost is achieved when the processing efficiency is "low". Therefore, by setting the processing efficiency to "low", production of workpiece W with a target production quantity Ntar can be completed before the prescribed end time Tw_fin, and the total cost Ctotal can be reduced. In this case, as shown by the arrow in Figure 11, the cycle time T_tact is determined to the predetermined longest time Ttact_max, which corresponds to a "low" processing efficiency.

[0074] The second example will be explained with reference to Figure 12. The second example is when the production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin, and the target cycle time Ttar_tact is shorter than the specified maximum time Ttact_max and longer than the specified intermediate time Ttact_mid.

[0075] In Figure 12, the white squares indicate the timing at which production of workpiece W with a target production quantity Ntar is completed on the lines representing tool costs Ctool1, Ctool2, and Ctool3. When the machining efficiency is "high" or "medium," production is completed before the specified end time Tw_fin. On the other hand, when the machining efficiency is "low," production is not completed before the specified end time Tw_fin. However, the white circles on the lines representing tool costs Ctool1, Ctool2, and Ctool3 indicate that the machining efficiency increases in the order of "low," "medium," and "high."

[0076] Similarly, on the lines showing the total costs Ctotal1, Ctotal2, and Ctotal3, white squares indicate the timing at which production of workpiece W with a target production quantity Ntar is completed. At each white square on the lines showing the total costs Ctotal1, Ctotal2, and Ctotal3, the lowest cost is achieved when the processing efficiency is "medium" among those where production is completed before the prescribed end time Tw_fin. Therefore, by setting the processing efficiency to "medium," it is possible to complete the production of workpiece W with a target production quantity Ntar before the prescribed end time Tw_fin, and the total cost Ctotal can be reduced. In this case, as shown by the arrow in Figure 12, the cycle time T_tact is determined to the predetermined intermediate time Ttact_mid, which corresponds to the processing efficiency of "medium." By completing production before the prescribed end time Tw_fin, it is possible to prevent the occurrence of overtime pay for employees.

[0077] The third example will be explained with reference to Figure 13. The third example is when the production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin, and the target cycle time Ttar_tact is shorter than the specified intermediate time Ttact_mid and longer than the specified minimum time Ttact_min.

[0078] In Figure 13, the white triangles indicate the timing at which production of workpiece W with a target production quantity Ntar is completed on the lines representing tool costs Ctool1, Ctool2, and Ctool3. When machining efficiency is "high," production is completed by the specified end time Tw_fin. On the other hand, when machining efficiency is "medium" or "low," production is not completed before the specified end time Tw_fin. However, the white circles on the lines representing tool costs Ctool1, Ctool2, and Ctool3 indicate that the cost increases in the order of "low," "medium," and "high" machining efficiency.

[0079] Similarly, on the lines representing total costs Ctotal1, Ctotal2, and Ctotal3, white triangles indicate the timing at which production of workpiece W with a target production quantity Ntar is completed. At each white triangle on the lines representing total costs Ctotal1, Ctotal2, and Ctotal3, the only cases where production is completed before the prescribed end time Tw_fin are those with a processing efficiency of "high". Therefore, by setting the processing efficiency to "high", it is possible to complete the production of workpiece W with a target production quantity Ntar before the prescribed end time Tw_fin, and the total cost Ctotal can be reduced. In this case, as shown by the arrow in Figure 13, the cycle time T_tact is determined to the predetermined shortest time Ttact_min corresponding to a processing efficiency of "high". By completing production before the prescribed end time Tw_fin, it is possible to prevent the occurrence of overtime pay for employees.

[0080] The fourth example will be explained with reference to Figure 14. The fourth example is the case where the production of workpiece W with a target production quantity Ntar does not finish before the specified end time Tw_fin. Therefore, this is the case where the target cycle time Ttar_tact is shorter than the specified shortest time Ttact_min.

[0081] The black circles in Figure 14 indicate the timing at which production of workpiece W with a target production quantity Ntar is completed on the lines representing tool costs Ctool1, Ctool2, and Ctool3. Regardless of whether the machining efficiency is "high," "medium," or "low," production cannot be completed before the specified end time Tw_fin. The black circles on the lines representing tool costs Ctool1, Ctool2, and Ctool3 indicate that the machining efficiency increases in the order of "low," "medium," and "high."

[0082] Similarly, on the lines showing total costs Ctotal1, Ctotal2, and Ctotal3, black circles indicate the timing at which production of workpiece W with a target production quantity Ntar is completed. At each black circle on the lines showing total costs Ctotal1, Ctotal2, and Ctotal3, the case where production can be completed as quickly as possible, even after the prescribed end time Tw_fin, is when the processing efficiency is set to "high". Therefore, by setting the processing efficiency to "high", the extension time can be minimized even after the prescribed end time Tw_fin. In this case, as shown by the arrow in Figure 14, the cycle time T_tact is determined to the predetermined shortest time Ttact_min corresponding to the processing efficiency being "high". Overtime pay for employees will be incurred because it is after the prescribed end time Tw_fin, but overtime pay can be kept to a minimum.

[0083] 9. Effects The production system 1 of this configuration, as shown in Figure 1, comprises a production facility 2 configured to process a workpiece W using a tool T through the operation or management of an operator, and a command device 6 that commands the production facility 2 regarding its operation. Here, the higher the processing efficiency of the tool T, the shorter the cycle time T_tact required to produce one workpiece W, and the higher the processing efficiency, the higher the tool cost Ctool associated with tool modification or tool change, and the labor cost Cperson is set according to the worker's working hours. The command device 6, as shown in Figures 11 to 13, comprises a cycle time determination unit 12 that determines the cycle time in such a way as to lower the total cost Ctotal, which includes the tool cost Ctool and the labor cost Cperson, and a command unit 13 that commands the production facility 2 to produce within the determined cycle time T_tact.

[0084] In other words, as shown in Figure 5, increasing machining efficiency increases the load on the tool T, thus increasing the tool cost Ctool associated with tool modification or tool change. Also, increasing machining efficiency shortens the cycle time T_tact required to produce one workpiece W, thus reducing the worker's working time and preventing an increase in labor cost Cperson. On the other hand, decreasing machining efficiency increases the cycle time T_tact required to produce one workpiece W, potentially increasing the worker's working time and thus the labor cost Cperson. However, decreasing machining efficiency reduces the load on the tool T, thus lowering the tool cost Ctool associated with tool modification or tool change. Thus, tool cost Ctool and labor cost Cperson have an inverse relationship with respect to machining efficiency.

[0085] As shown in Figures 11 to 13, the takt time determination unit 12, which constitutes the command device 6, uses the total cost Ctotal, which includes the tool cost Ctool and the labor cost Cperson, to determine a takt time T_tact that minimizes the total cost Ctotal. Then, the command unit 13, which also constitutes the command device 6, commands the production equipment 2 to perform machining at the determined takt time T_tact. Consequently, the workpiece W can be machined with a machining efficiency that minimizes the total cost Ctotal, thereby achieving optimal production. In this way, the production system 1 can achieve optimal production by considering the tool cost Ctool and the labor cost Cperson.

[0086] Furthermore, as shown in Figure 8, the cycle time determination unit 12 calculates a target cycle time Ttar_tact, which is the target value of the cycle time T_tact required to produce workpieces W of the target production quantity Ntar by the target completion time (in this embodiment, for example, the specified end time Tw_fin), based on the target production quantity Ntar of workpieces W and the target completion time for producing workpieces W of the target production quantity Ntar (in this embodiment, for example, the specified end time Tw_fin). Based on this target cycle time Ttar_tact, the cycle time T_tact is determined. In this way, the cycle time T_tact can be appropriately set by using the target cycle time Ttar_tact calculated based on the target production quantity Ntar and the target completion time.

[0087] Furthermore, in this configuration, as shown in Figure 7, the worker is a person whose work schedule has a predetermined end time Tw_fin. The target completion time is also the predetermined end time Tw_fin. Therefore, the target cycle time Ttar_tact is calculated so that the production of workpieces with a target production quantity Ntar is completed before the predetermined end time Tw_fin. As a result, the cycle time T_tact can be set to an appropriate time that takes the predetermined end time Tw_fin into consideration.

[0088] Furthermore, as shown in Figure 7, the time increase rate of tool cost Ctool is greater than the time increase rate of labor cost Cperson within the worker's working hours before the prescribed end time Tw_fin. As shown in Figures 9 and 10, the cycle time T_tact is configured to be set within a range from a predetermined minimum time Ttact_min to a predetermined maximum time Ttact_max. As shown in Figures 9 and 10, if the calculated target cycle time Ttar_tact is longer than the predetermined maximum time Ttact_max, the cycle time determination unit 12 determines the cycle time T_tact to the predetermined maximum time Ttact_max.

[0089] Since the calculated cycle time T_tact is longer than the predetermined maximum time Ttact_max, production of the target production quantity Ntar can be completed by the predetermined end time Tw_fin. In this case, since the cycle time T_tact is set to the predetermined maximum time Ttact_max, the machining efficiency is set to the lowest possible value within the settable range. Therefore, the tool cost Ctool can be minimized. Furthermore, as shown in Figure 7, before the predetermined end time Tw_fin, the rate of increase in tool cost Ctool over time is higher than the rate of increase in labor cost Cperson over time. Therefore, before the predetermined end time Tw_fin, the total cost Ctotal can also be minimized.

[0090] Furthermore, as shown in Figures 9 and 10, the cycle time determination unit 12 determines the cycle time T_tact to the predetermined shortest time Ttact_min if the calculated target cycle time Ttar_tact is shorter than the predetermined shortest time Ttact_min. Since the calculated target cycle time Ttar_tact is shorter than the predetermined shortest time Ttact_min, it becomes impossible to complete the production of the target production quantity Ntar by the predetermined end time Tw_fin. In this case, since the cycle time T_tact is determined to the predetermined shortest time Ttact_min, the processing efficiency is set to the highest possible value within the settable range. Therefore, the extension time from the predetermined end time Tw_fin for the worker's working hours can be reduced. Additional costs associated with the extension of the worker's working hours can be suppressed.

[0091] Furthermore, as shown in Figure 8, the cycle time determination unit 12 acquires the current target production quantity Ntar and a specified end time Tw_fin, which is one of the target completion times, each time one or a predetermined quantity of workpieces W are processed. In other words, the cycle time T_tact is determined based on the new information acquired each time one or a predetermined quantity of workpieces W are processed. Therefore, even if the situation changes due to various circumstances, production can be achieved with a cycle time T_tact that appropriately responds to the changed situation.

[0092] Furthermore, the cycle time T_tact is configured to be set within a range from a predetermined minimum time Ttact_min to a predetermined maximum time Ttact_max, which is required to meet the target quality of the workpiece W. Therefore, by setting the cycle time T_tact within the above range, the quality of the workpiece W can be set to the desired target quality.

[0093] Furthermore, as shown in Figure 5, the interval for tool modification or tool change is determined based on machining efficiency. Therefore, the tool cost Ctool associated with tool modification or tool change will be proportional to the machining efficiency.

[0094] Furthermore, as shown in Figure 2, in this embodiment, production equipment 2 is a grinding machine that grinds the workpiece W using a grinding wheel as the tool T. Then, as shown in Figure 5, the interval for tool correction or tool change of the grinding wheel is determined based on the machining efficiency. When the tool T is the grinding wheel of the grinding machine, it is evident that the tool cost Ctool associated with tool correction and tool change is in line with the machining efficiency.

[0095] Furthermore, as shown in Figure 9, the command unit 13 may also command the production equipment 2 to set a processing efficiency corresponding to the determined cycle time T_tact. Alternatively, as shown in Figure 10, the command unit 13 may also command the production equipment 2 to set unit processing times Tmc_min, Tmc_mid, and Tmc_max corresponding to the determined cycle times Ttact_min, Ttact_mid, and Ttact_max.

[0096] In particular, in the latter case, this system is adopted when the production system 1 is configured as follows: Multiple production equipment 2 to 4 each perform machining, pre-machining, and post-machining processes. Production equipment 2, which performs machining, performs tool correction or tool change and includes the unit machining time required for machining one workpiece W in the command data for machining conditions. Then, as shown in Figure 6, the command device 6 obtains the relationship between the cycle times Ttact_min, Ttact_mid, Ttact_max and the unit machining times Tmc_min, Tmc_mid, Tmc_max by actually or simulating each process performed by production equipment 2 to 4. Then, as described above, the command unit 13 commands production equipment 2 to perform the unit machining times Tmc_min, Tmc_mid, Tmc_max corresponding to the determined cycle times Ttact_min, Ttact_mid, Ttact_max.

[0097] In this way, by actually executing or simulating each process using production equipment 2-4, the unit processing times Tmc_min, Tmc_mid, and Tmc_max are determined while taking into account the other production equipment 3 and 4. Therefore, the unit processing times Tmc_min, Tmc_mid, and Tmc_max can be set to include the various factors in production equipment 2-4. As a result, optimal production can be achieved.

[0098] Furthermore, as shown in Figure 8, the command device 6 performs the processes S11 to S16 for each workpiece W. Here, the target production quantity Ntar may change depending on the production situation. For example, the target production quantity Ntar may change due to delays or advances in the arrival of raw materials, or the need for processing of urgent items. In such cases, the production system 1 initially calculates the target cycle time Ttar_tact based on the initial production plan, which includes the initial target production quantity Ntar and the initial target completion time. Then, it starts production with the calculated target cycle time Ttar_tact.

[0099] The command device 6 then sequentially acquires the current target production quantity Ntar and the current target completion time, which is the specified end time Tw_fin, each time production is in progress based on the initial plan. If at least one of the acquired current target production quantity Ntar and target completion time Tw_fin is changed, the command device 6 recalculates the target takt time Ttar_tact based on the revised production plan that includes the changed target production quantity Ntar and target completion time Tw_fin. The command device 6 then re-determines the takt time T_tact in real time based on the recalculated target takt time Ttar_tact. Thus, optimal production can be achieved in response to changes in the production status.

[0100] (Embodiment 2) The processing of the production system 1 in Embodiment 2 will be described with reference to Figures 15 and 16. In Embodiment 1 described above, the specified end time Tw_fin was used as an example of the target completion time. In addition, in Embodiment 2, the target completion time can also be set to the start time of the next production by production equipment 2, Ts_next, in the production plan.

[0101] For example, if the start time Ts_next for the next production arrives before the prescribed end time Tw_fin at the current time Tnow, then the workpiece W currently being produced must be completed before the start time Ts_next for the next production. Furthermore, the next production cannot start until the start time Ts_next. In this case, if the current production is finished too early, the worker's labor may cease to exist. Therefore, production system 1 processes as follows:

[0102] As shown in Figure 15, the takt time determination unit 12 of the command device 6 first obtains the target production quantity Ntar of the workpiece W from the management device 5 (S21). Next, the takt time determination unit 12 of the command device 6 obtains from the management device 5 the earlier of two target completion times for producing workpiece W of target production quantity Ntar: the specified end time Tw_fin and the other target start time Ts_next for the next production (S22). If the specified end time Tw_fin is earlier than the start time Ts_next for the next production, the process is the same as in Embodiment 1. Therefore, in this embodiment, we will explain assuming that the start time Ts_next for the next production is earlier than the specified end time Tw_fin.

[0103] Next, the takt time determination unit 12 of the command device 6 calculates the target takt time Ttar_tact, which is the target value of the takt time T_tact required to produce the workpiece W of the target production quantity Ntar by the start time Ts_next of the next production, based on the target production quantity Ntar and the start time Ts_next, which is the target completion time (S23). Subsequently, the takt time determination unit 12 of the command device 6 determines the takt time T_tact based on the target takt time Ttar_tact (S24). The determination of the takt time T_tact is the same as in Embodiment 1.

[0104] After the takt time determination unit 12 of the command device 6 determines the takt time T_tact (S24), the command unit 13 of the command device 6 issues a command to the production equipment 2 to produce at the determined takt time T_tact (S25). Subsequently, the acquisition unit 11 of the command device 6 acquires processing result information for each workpiece W from the production equipment 2 (S26).

[0105] Next, the command device 6 determines whether or not production of workpiece W with a target production quantity Ntar has been completed (S27). If production has not been completed (S27: No), the command device 6 repeats the process from S21. In other words, the command device 6 performs the processes S21 to S26 for each workpiece W. Accordingly, each time a workpiece W is processed, the takt time determination unit 12 of the command device 6 sequentially acquires the current target production quantity Ntar and the start time of the next production as the target completion time Ts_next or the specified end time Tw_fin, and recalculates the target takt time Ttar_tact. Then, based on the recalculated target takt time Ttar_tact, the takt time determination unit 12 re-determines the takt time T_tact in real time.

[0106] On the other hand, if production of workpiece W with a target production quantity Ntar is completed (S27: Yes), the aggregated data output unit 14 of the command device 6 aggregates data related to multiple workpieces W and outputs the aggregated data to the management device 5 (S28).

[0107] In the first example, as shown by the white circles in Figure 16, regardless of whether the processing efficiency is "high," "medium," or "low," the current production is completed before the start time Ts_next of the next production. In this case, the cycle time T_tact is determined to be the predetermined longest time Ttact_max, which corresponds to the "low" processing efficiency that results in the lowest total cost Ctotal. In the second example, as shown by the white squares in Figure 16, the current production is completed before the start time Ts_next of the next production when the processing efficiency is "high" or "medium." In this case, the cycle time T_tact is determined to be the predetermined intermediate time Ttact_mid, which corresponds to the "medium" processing efficiency that results in the lowest total cost Ctotal among the "high" and "medium" processing efficiencys. In the third example, as shown by the white triangles in Figure 16, the current production is completed before the start time Ts_next of the next production only when the processing efficiency is "high." In this case, the cycle time T_tact is determined to be the predetermined shortest time Ttact_min, which corresponds to a "high" machining efficiency.

[0108] The target production quantity Ntar and the start time of the next production run Ts_next may change depending on the production situation. For example, delays or early arrivals of raw material deliveries, or the need for processing of urgent items, may cause changes in the target production quantity Ntar or the start time of the next production run Ts_next. In such cases, production system 1 initially calculates the target cycle time Ttar_tact based on the initial production plan, which includes the initial target production quantity Ntar and the initial target completion time. Then, it starts production at the calculated target cycle time Ttar_tact.

[0109] The command device 6 then sequentially acquires the current target production quantity Ntar and the current target completion time Ts_next,Tw_fin each time production is in progress based on the initial plan. If at least one of the acquired current target production quantity Ntar and target completion time Ts_next,Tw_fin is changed, the command device 6 recalculates the target cycle time Ttar_tact based on the revised production plan that includes the changed target production quantity Ntar and target completion time Ts_next,Tw_fin. The command device 6 then re-determines the cycle time T_tact in real time based on the recalculated target cycle time Ttar_tact. Thus, optimal production can be achieved in response to changes in the production status.

[0110] This description focuses on employees in a work arrangement where working hours are defined as a set start time Tw_start and a set end time Tw_fin (fixed time). It can also be applied to production arrangements that are not dependent on individual workers, such as 24-hour continuous production in a three-shift system.

[0111] (Embodiment 3) The processing of production system 1 in Embodiment 3 will be explained with reference to Figure 17. In Embodiments 1 and 2, the labor cost Cperson was constant from the prescribed start time Tw_start to the prescribed end time Tw_fin (fixed time) during working hours. In this embodiment, as shown by the thick solid line in Figure 17, the target is a work arrangement in which the labor cost Cperson increases as the working hours increase, such as part-time work arrangements, from the prescribed start time Tw_start to the prescribed end time Tw_fin during working hours.

[0112] As shown in Figure 17, the time increase rate of tool costs Ctool1, Ctool2, and Ctool3 is assumed to be greater than the time increase rate of labor cost Cperson within the worker's working hours, prior to the prescribed end time Tw_fin. Furthermore, the worker's working hours are assumed to end at the prescribed end time Tw_fin, and there are no working hours after the prescribed end time Tw_fin.

[0113] In this embodiment, the production system 1 performs essentially the same processing as in the first to third examples, referring to Figures 11 to 13 in Embodiment 1. In Figure 17, the first example is indicated by a white circle, the second example by a white square, and the third example by a white triangle. In the first example, the takt time determination unit 12 of the command device 6 determines the takt time T_tact to a predetermined maximum time Ttact_max, which corresponds to a "low" processing efficiency. In the second example, the takt time determination unit 12 of the command device 6 determines the takt time T_tact to a predetermined intermediate time Ttact_mid, which corresponds to a "medium" processing efficiency. In the third example, the takt time determination unit 12 of the command device 6 determines the takt time T_tact to a predetermined minimum time Ttact_min, which corresponds to a "high" processing efficiency. In this case as well, the same effects as in Embodiment 1 are achieved.

[0114] (Embodiment 4) The processing of the production system 1 in Embodiment 4 will be explained with reference to Figures 18 to 22. In Embodiment 1, the target completion time was set to the predetermined end time Tw_fin. In this embodiment, the target completion time is set to the target production completion time Ttar_fin for completing the production of workpiece W with a target production quantity Ntar.

[0115] Furthermore, in this embodiment, as shown by the thick solid lines in Figures 19 to 22, the worker is a person whose work schedule has a predetermined end time Tw_fin. And, similar to Embodiment 1, the time increase rate of tool costs Ctool1 to Ctool3 is greater than the time increase rate of labor cost Cperson during the worker's working hours before the predetermined end time Tw_fin. On the other hand, unlike Embodiment 1, the time increase rate of tool costs Ctool1 to Ctool3 is less than the time increase rate of labor cost Cperson during the worker's working hours after the predetermined end time Tw_fin.

[0116] The processing of the command device 6 will be explained with reference to Figure 18. Here, we will explain the processing performed by the worker from the start to the end of their workday using the command device 6.

[0117] The takt time determination unit 12 of the command device 6 first obtains the target production quantity Ntar of the workpiece W from the control device 5 (S31). Next, the takt time determination unit 12 of the command device 6 obtains the target production completion time Ttar_fin from the control device 5, which is one of the target completion times for producing workpiece W of the target production quantity Ntar (S32). Subsequently, the takt time determination unit 12 of the command device 6 calculates the target takt time Ttar_tact, which is the target value of the takt time T_tact for producing workpiece W of the target production quantity Ntar by the target production completion time Ttar_fin, based on the target production quantity Ntar and the target production completion time Ttar_fin (S33).

[0118] Next, the takt time determination unit 12 of the command device 6 determines the takt time T_tact within the target takt time Ttar_tact such that the total cost Ctotal is low (S34). Subsequently, the command unit 13 of the command device 6 issues a command to the production equipment 2 to start production at the determined takt time T_tact (S35).

[0119] Next, the acquisition unit 11 of the command device 6 acquires processing result information for each workpiece W from the production equipment 2 (S36). Subsequently, the command device 6 determines whether or not production of workpiece W with a target production quantity Ntar has been completed (S37). If production has not been completed (S37: No), the command device 6 repeats the process from S31. On the other hand, if production of workpiece W with a target production quantity Ntar has been completed (S37: Yes), the aggregated data output unit 14 of the command device 6 aggregates data related to multiple workpieces W and outputs the aggregated data to the management device 5 (S38).

[0120] The specific processing of the takt time determination unit 12, that is, the processing of S34 in Figure 18, will be explained with reference to Figures 19 to 22. In the first example, as shown in Figure 19, the production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin, regardless of whether the processing efficiency is "high," "medium," or "low." In this case, similar to the first example of Embodiment 1 (Figure 9), as indicated by the arrow in Figure 19, the takt time T_tact is determined to the predetermined longest time Ttact_max, which corresponds to the processing efficiency of "low" that results in a low total cost Ctotal.

[0121] In the second example, Figure 20 shows that when the machining efficiency is "high" or "medium," the production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin. Furthermore, production is completed before the target production completion time Ttar_fin for all three machining efficiency levels: "high," "medium," and "low." In this case, the total cost Ctotal is lowest when the machining efficiency is "medium." Therefore, as indicated by the arrow in Figure 20, the cycle time T_tact is determined to be the predetermined intermediate time Ttact_mid, which corresponds to the machining efficiency of "medium" that results in the lowest total cost Ctotal.

[0122] In the third example, Figure 21 shows that production of workpiece W with a target production quantity Ntar is completed before the specified end time Tw_fin only when the processing efficiency is "high". Also, production is completed before the target production completion time Ttar_fin for all processing efficiency levels: "high", "medium", and "low". In this case, the total cost Ctotal is lowest when the processing efficiency is "high". Therefore, as shown by the arrow in Figure 21, the cycle time T_tact is determined to be the predetermined shortest time Ttact_min corresponding to the processing efficiency of "high" which results in the lowest total cost Ctotal.

[0123] In the fourth example, Figure 22 shows that, regardless of whether the processing efficiency is "high," "medium," or "low," the production of workpiece W with a target production quantity Ntar does not finish before the specified end time Tw_fin. However, production is completed before the target production completion time Ttar_fin regardless of whether the processing efficiency is "high," "medium," or "low." In this case, the total cost Ctotal is lowest when the processing efficiency is "high." Therefore, as shown by the arrow in Figure 22, the cycle time T_tact is determined to be the predetermined shortest time Ttact_min corresponding to the processing efficiency of "high" which results in the lowest total cost Ctotal.

[0124] In the first to fourth examples, if production is completed before the target production completion time Ttar_fin, the cycle time T_tact is determined such that the total cost Ctotal, including tool costs Ctool and labor costs Cperson, is low, regardless of whether it is before or after the worker's prescribed end time Tw_fin. [Explanation of Symbols]

[0125] 1. Production System 2,3,4 Production equipment 6 Command device 12. Tact Time Determination Unit 13 Command Department T-tool W Workpiece T_tact Tact Time Ctool, Ctool1, Ctool2, Ctool3 Tool Costs Cperson labor costs Total cost: Ctotal, Ctotal1, Ctotal2, Ctotal3

Claims

1. Production equipment configured to process workpieces using tools through the operation or management of an operator, A control device that issues commands to the production equipment regarding the operation of the production equipment, Equipped with, The higher the machining efficiency of the tool, the shorter the cycle time required to produce one workpiece; the higher the machining efficiency, the higher the tool cost associated with tool modification or tool change; and the labor cost is set according to the working hours of the operator. The aforementioned cycle time is configured to be set within a range from a predetermined minimum time to a predetermined maximum time that satisfies the target quality of the workpiece. The command device is A takt time determination unit calculates a target takt time, which is a target value of the takt time required to produce the target quantity of workpieces by the target completion time, based on the target production quantity of the workpieces and the target completion time for producing the workpieces in the target production quantity, and determines the takt time based on the target takt time in order to reduce the total cost, including the tool cost and the labor cost. A control unit that instructs the production equipment to produce within the determined cycle time, A production system equipped with these features.

2. Production equipment configured to process workpieces using tools through the operation or management of an operator, A control device that issues commands to the production equipment regarding the operation of the production equipment, Equipped with, The higher the machining efficiency of the tool, the shorter the cycle time required to produce one workpiece; the higher the machining efficiency, the higher the tool cost associated with tool modification or tool change; and the labor cost is set according to the working hours of the operator. Multiple production facilities perform machining processes, pre-machining processes, and post-machining processes, respectively. The production equipment that performs the machining process performs tool modification or tool change, and includes the unit machining time required for the machining process of one workpiece in the command data of the machining conditions. The command device is An acquisition unit that acquires the relationship between the cycle time and the unit processing time by actually or in simulation executing each process by the aforementioned production equipment, A cycle time determination unit that determines the cycle time in such a way as to reduce the total cost, including the tool cost and the labor cost, A command unit that commands the production equipment performing the machining to perform the machining, so as to produce within the determined cycle time, the cycle time corresponding to the determined cycle time, A production system equipped with these features.

3. Production equipment configured to process workpieces using tools through the operation or management of an operator, A control device that issues commands to the production equipment regarding the operation of the production equipment, Equipped with, The cycle time required to produce one of the aforementioned workpieces includes a first time required for machining the workpiece using the aforementioned tool, and a second time required for tool modification or tool change. The higher the machining efficiency of the tool, the shorter the first time becomes, while the second time per workpiece produced becomes longer. Furthermore, the reduction in the first time due to the increase in processing efficiency is greater than the extension in the second time, so there is a relationship in which the higher the processing efficiency, the shorter the cycle time. The higher the machining efficiency, the higher the tool cost associated with tool modification or tool replacement, and the labor cost is set according to the worker's working hours. The command device is A cycle time determination unit that determines the cycle time in such a way as to reduce the total cost, including the tool cost and the labor cost, A control unit that instructs the production equipment to produce within the determined cycle time, A production system equipped with these features.

4. The cycle time required to produce one of the workpieces includes a first time required for machining the workpiece using the tool, and a second time required for tool modification or tool change. The higher the machining efficiency of the tool, the shorter the first time becomes, while the second time per workpiece produced becomes longer. Furthermore, the production system according to claim 1 or 2, wherein the reduction in the first time due to the increase in processing efficiency is greater than the extension in the second time, so that the higher the processing efficiency, the shorter the cycle time.

5. The aforementioned cycle time determination unit, Based on the target production quantity of the workpiece and the target completion time for producing the target production quantity of the workpiece, a target cycle time is calculated, which is the target value of the cycle time required to produce the target production quantity of the workpiece by the target completion time. The production system according to claim 2 or 3, wherein the cycle time is determined based on the target cycle time.

6. The aforementioned worker is a person whose work schedule includes a set end time for working hours. The production system according to claim 1, wherein the target completion time is the prescribed end time.

7. If, during the worker's working hours, prior to the prescribed end time, the rate of increase in tool costs over time is greater than the rate of increase in labor costs over time, The aforementioned cycle time is configured to be set within a range from a predetermined minimum time to a predetermined maximum time. The production system according to claim 6, wherein the cycle time determination unit determines the cycle time to the predetermined maximum time if the calculated target cycle time is longer than the predetermined maximum time.

8. The production system according to claim 7, wherein the cycle time determination unit determines the cycle time to the predetermined shortest time if the calculated target cycle time is shorter than the predetermined shortest time.

9. The aforementioned worker is a person whose work schedule includes a set end time for working hours. If, during the worker's working hours, prior to the prescribed end time, the rate of increase in tool costs over time is greater than the rate of increase in labor costs over time, During the worker's working hours, after the prescribed end time, the rate of increase in tool costs over time is smaller than the rate of increase in labor costs over time. The production system according to any one of claims 1 to 3, wherein the cycle time determination unit determines the cycle time such that the total cost, including the tool cost and the labor cost, is low, both before and after the prescribed end time.

10. The production system according to claim 1, wherein the target completion time is the start time of the next production by the production equipment in the production plan.

11. The aforementioned cycle time determination unit, Based on the initial production plan including the target production quantity and the target completion time, the target cycle time is calculated. The current target production quantity and target completion time are acquired sequentially. If at least one of the acquired current target production quantity and target completion time is changed, the target cycle time is recalculated based on the revised production plan which includes the changed target production quantity and target completion time. The production system according to claim 1, wherein the cycle time is re-determined in real time based on the recalculated target cycle time.

12. The production system according to claim 11, wherein the cycle time determination unit obtains the current target production quantity and the target completion time each time one or a predetermined number of workpieces are processed.

13. The production system according to claim 2 or 3, wherein the cycle time is configured to be set within a range from a predetermined minimum time to a predetermined maximum time that satisfies the target quality of the workpiece.

14. The production system according to any one of claims 1 to 3, wherein the interval for tool modification or tool change is determined based on the machining efficiency.

15. The aforementioned production equipment is a grinding machine that grinds the workpiece using a grinding wheel as a tool, The production system according to claim 14, wherein the interval for tool modification or tool change is determined based on the machining efficiency of the grinding wheel.

16. The production system according to any one of claims 1 to 3, wherein the command unit commands the production equipment to perform the processing according to the determined cycle time.

17. Multiple production facilities perform machining processes, pre-machining processes, and post-machining processes, respectively. The production equipment that performs the aforementioned machining is Perform the aforementioned tool modification or tool replacement, The command data for machining conditions includes the unit machining time required for the machining process of one of the workpieces. The command device obtains the relationship between the cycle time and the unit processing time by actually or in simulation executing each process by the production equipment. The production system according to any one of claims 1 to 3, wherein the command unit commands the production equipment that performs the machining to perform the machining, the unit machining time corresponding to the determined takt time.

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