Switching calculation method and switching calculation device

Abstract

To provide a low-risk and low-cost transition date for switching from old parts to new parts. [Solution] The switching calculation device 10 includes a parts identification unit 19, a date calculation unit 17, and a display control unit 18. The parts identification unit 19 refers to parts management data that associates a parent part to be produced with one or more child parts used in the production of that parent part, and identifies the parent part that will use the child part specified in the switching instruction before the switching. The date calculation unit 17 reduces the inventory of child parts that are scheduled to be consumed according to the production plan of the parent part identified by the parts identification unit 19, and predicts the switching date when the inventory of those child parts will reach the target inventory number specified in the switching instruction. The display control unit 18 displays the switching date predicted by the date calculation unit 17.

Description

Technical Field

[0001] The present invention relates to a switching calculation method and a switching calculation device.

Background Art

[0002] In a production system that manufactures a product using one or more components, there are many situations where a component used in the product is redesigned from an old component to a new component that plays an equivalent role. Since the new component is generally superior to the old component in terms of lower cost or higher quality, producers want to actively switch from the old component before the design change to the new component after the design change. However, in a situation where a large amount of old components have already been secured as inventory, the old components can be monetized by switching to new components after using up the old components.

[0003] Therefore, Patent Document 1 describes a design change automation system having the following configuration. · An "item master" that holds component attribute information · A "BOM (Bill of Materials)" that arranges the components in the item master on a tree · A "change master" that has a 'change number' for managing design changes to the BOM by replacing the date with a name and an 'alternative date function' that allows the date to be changed · "MRP (Material Requirements Planning)" that performs a required quantity expansion to calculate when and how much each component is needed from the production plan · An "RC (Running Change) database" that manages the automatic switching from the inventory consumption prediction date including the plan to switch component A on a certain BOM to component B

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] Conventional technologies, such as those described in Patent Document 1, require that parts subject to design changes be managed in an RC database in advance in order to exclude them from new orders. Therefore, it is necessary to prepare an RC database and a new order exclusion system separately from MRP, which results in high costs. On the other hand, some production system managers have a need for a low-risk system that does not require integration with MRP ordering processes, and only needs to know the appropriate switchover date from old parts to new parts. A low-cost, simple system that meets this need has not been provided by conventional technologies such as Patent Document 1.

[0006] This invention was made in view of the above circumstances, and its main objective is to provide a low-risk and low-cost transition date for switching from old parts to new parts. [Means for solving the problem]

[0007] To solve the above problems, the switching calculation method of the present invention has the following features. The present invention provides a switching calculation device comprising a component identification unit, a date calculation unit, and a display control unit. The aforementioned part identification unit refers to part management data that associates the parent part to be produced with one or more sub-parts used in the production of that parent part, and identifies the parent part that uses the sub-part specified in the switching instruction before the switching. The date calculation unit reduces the inventory of child parts that are scheduled to be consumed according to the production plan of the parent parts identified by the part identification unit, and predicts the changeover date on which the inventory of those child parts will reach the target inventory number specified in the changeover instruction. The display control unit is characterized by displaying the switching date predicted by the date calculation unit. Other features will be described later. [Effects of the Invention]

[0008] According to the present invention, a transition date for switching from old parts to new parts can be provided with low risk and low cost. [Brief explanation of the drawing]

[0009] [Figure 1] This is an explanatory diagram showing the Bill of Materials (BOM) for product FG001 according to this embodiment, before and after component changeover. [Figure 2] This is an explanatory diagram showing the Bill of Materials (BOM) for product FG002 according to this embodiment, before and after component changeover. [Figure 3] This is a diagram illustrating the configuration of the production management system according to this embodiment. [Figure 4] This is a hardware configuration diagram of the switching computing device according to this embodiment. [Figure 5] This flowchart shows the processing of the switching calculation device according to this embodiment. [Figure 6] This is a table showing the item master for this embodiment. [Figure 7] This is a table showing the BOM master for this embodiment. [Figure 8] This is a table showing the change master related to this embodiment. [Figure 9] This is a table showing the BOM master for this embodiment. [Figure 10] This is a table showing the output data of the MRP related to this embodiment. [Figure 11] This is a screen diagram showing a first example of an input screen according to this embodiment. [Figure 12] This is a screen diagram showing a second example of the input screen according to this embodiment. [Figure 13] This flowchart shows the processing of the switching calculator, which is executed from terminal A in Figure 5, according to this embodiment. [Figure 14] This is a table showing the calculation process data of the date calculation unit according to this embodiment. [Figure 15] This is a flowchart showing the processing of the switching calculation device executed from terminal B in Figure 13 according to this embodiment. [Figure 16] It is a screen diagram showing a simulation result display screen related to this embodiment. [Figure 17] It is a table showing the calculation process data of the date calculation unit when the switching date is advanced due to the available number related to this embodiment becoming 0. [Figure 18] It is a table showing the calculation process data of the date calculation unit when the switching date is advanced due to the available number related to this embodiment becoming less than 0. [Figure 19] It is a table showing the calculation process data of the date calculation unit when the switching date is postponed due to the available number related to this embodiment exceeding 0 even after the initial switching date has passed. [Figure 20] It is a table showing the calculation process data of the date calculation unit when the available number increases after the switching date related to this embodiment has been determined. [Figure 21] It is a table showing the calculation process data of the date calculation unit related to this embodiment.

Mode for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, referring to FIGS. 1 and 2, the terms of this embodiment are defined.

[0011] FIG. 1 is an explanatory diagram showing the BOM before and after component switching for product FG001. First, component switching means switching from the component before design change to the component after design change as the component used in production. Also, the components to be switched are not limited to components designed by the same developer, and for example, it may be any switching between components, such as switching from a component supplied by Company A to a component of Company B independently designed from Company A's component.

[0012] The BOM is a data structure that summarizes the parts required to manufacture a product in a tree-like form. In the pre-switch BOM301, product FG001, semi-finished product SG001, and parts RM001 and RM002 are connected in order from the root of the tree structure. Therefore, the pre-switch BOM301 indicates that product FG001 is manufactured from semi-finished product SG001, and that semi-finished product SG001 is manufactured from parts RM001 and RM002. A "parent component" refers to an element that corresponds to the parent node in the BOM tree, and a "child component" refers to an element that corresponds to the child node in the BOM tree. For example, semi-finished product SG001 is the parent component for components RM001 and RM002, and components RM001 and RM002 are child components for semi-finished product SG001.

[0013] The pre-switch BOM301 shows the state before the design change, and the pre-switch BOM302 shows the state after the design change. Here, the "part RM001" in the pre-switch BOM301, which is highlighted in the diagram, is the "old part" before the design change (before the switch), and the "part RM011" in the pre-switch BOM302, which is also highlighted in the diagram, is the "new part" after the design change (after the switch). Furthermore, both the old part RM001 and the new part RM011 are sub-parts of the parent part "semi-finished product SG001". Therefore, part RM001 is designated as the "old sub-part" and part RM011 as the "new sub-part".

[0014] Figure 2 is an explanatory diagram showing the BOM (Bill of Materials) for product FG002 before and after component changeover. The pre-design change BOM311 indicates that product FG002 is produced from semi-finished product SG002, and semi-finished product SG002 is produced from parts RM001 and RM003. The pre-switch BOM312 after the design change indicates that product FG002 is produced from semi-finished product SG002, and semi-finished product SG002 is produced from parts RM011 and RM003. In other words, the sub-part of the parent part "semi-finished product SG002" will be redesigned from the old sub-part "part RM001" to the new sub-part "part RM011".

[0015] Next, we will explain the lifespan of each component. Each component has an individually set validity period, from its effective start date to its effective end date. During the validity period, the procurement (new orders) of the part, its storage as inventory, and the manufacture of parent parts that use the part as a sub-part are permitted. After the validity period, however, while the part can still be stored as inventory, efforts are made to minimize the procurement and consumption of the part. Therefore, the switchover date for a design change from an old sub-component to a new sub-component is the day after the expiration date of the old sub-component and the start date of the new sub-component's validity. This ensures that there is no overlap or gaps in the validity periods of the old and new sub-components.

[0016] Furthermore, similar to Patent Document 1, in this embodiment as well, by using up the old sub-parts inventory before starting to use new sub-parts, the old sub-parts can be monetized, and the long-term storage costs (warehouse costs) of the old sub-parts can be reduced. On the other hand, in this embodiment as well, instead of using up the old sub-parts inventory (= reducing the inventory to zero), it is also possible to maintain a certain amount of old sub-parts inventory (target inventory quantity) for maintenance purposes such as repair and replacement.

[0017] Next, I will explain the process for changing the switchover date. Changes in production conditions may cause the consumption of old sub-components to deviate from the initial production plan. For example, if more sub-components are consumed than planned (increasing production demand for parent components), the old sub-components may be used up earlier than the original switchover date. In such cases, it is desirable to bring forward the original switchover date and switch to the new components earlier than planned. On the other hand, if the production demand for the parent component is less than the production plan, the consumption of the old sub-component will also be low. Therefore, it is desirable to postpone the initial switchover date and switch to the new component later than planned.

[0018] Therefore, the switching calculation device 10 (Figure 3) of this embodiment supports both of the following methods. The "fixed calculation method" is a method in which the date on which the old parts reach the target inventory level is calculated once, and that calculated date is set as the fixed switchover date. The "running change method" is a method in which, if the previous changeover date deviates from the date when the target inventory level is reached due to changes in assumptions such as the demand for old parts and production plans, the current changeover date, which is an alternative date from the previous changeover date, is recalculated based on the new assumptions. The running change method allows for measures such as appropriately accelerating the transition date to reduce the need for additional orders of old parts, or appropriately delaying the transition date to reduce the surplus (dead stock) of old parts.

[0019] Figure 3 is a diagram showing the configuration of the production management system 100. The switching calculation device 10 includes a change master 11, a BOM master 12, an item master 13, a production planning system 14, an MRP 15, an inventory management unit 16, a date calculation unit 17, a display control unit 18, and a parts identification unit 19. The switching calculation device 10 is also connected to an input device 21 for inputting input data to the switching calculation device 10 and a display device 22 for displaying output data from the switching calculation device 10.

[0020] The item master 13 manages attribute information such as the order lot number for each part (see Figure 6 for details). As explained in Figures 1 and 2, the BOM master 12 is parts management data that arranges the relationships between each part in the item master 13 in a tree structure, and associates the parent part to be produced with one or more child parts used in the production of that parent part. Furthermore, the BOM master 12 associates the validity period of each part (see Figure 7 for details). The change master 11 manages the changeover date for parts in the BOM master 12 (see Figure 8 for details).

[0021] The production planning system 14 creates a production plan that determines the production volume and timing of products according to the demand forecast for the products to be produced. The MRP 15 receives the production plan from the production planning system 14 and performs requirements calculations that show when and in what quantities each component used in the production of the product is needed (see Figure 10 for details). In addition, the requirements calculation of the MRP 15 increases inventory levels based on future confirmed incoming shipments and decreases inventory levels based on future consumption plans. The inventory management department 16 manages the inventory quantity of each component at each point in time, based on the requirements calculation from the MRP 15.

[0022] The component identification unit 19 refers to the BOM master 12 to identify the parent component that uses the child component specified in the switching instruction before the switching. The date calculation unit 17, for the parent component identified by the component identification unit 19, reduces the inventory of child components that are scheduled to be consumed according to the requirements development in the MRP 15, which reflects the production plan of the parent component, and predicts the switchover date when the inventory of those child components reaches the target inventory level specified in the switchover instruction. Specifically, the date calculation unit 17 uses the current inventory level of the old component shown by the inventory management unit 16 as a starting point, and increases or decreases the future inventory level according to the requirements development in the MRP 15, and calculates the switchover date when the inventory level of the old component reaches the target inventory level (see Figure 14 for details). Furthermore, the date calculation unit 17 predicts the switchover date on which the inventory of sub-components will reach zero if the target inventory quantity specified in the switchover instruction is zero, thereby ensuring that the old components are used up.

[0023] The display control unit 18 displays on the display device 22 an input screen (see Figures 11 and 12 for details) that prompts the input device 21 to input data used in the calculations of the date calculation unit 17, and an output screen (see Figure 16 for details) that shows the calculation results of the date calculation unit 17. For example, the display control unit 18 displays the transition date predicted by the date calculation unit 17.

[0024] Figure 4 is a hardware configuration diagram of the switching computing device 10. Each switching computing device 10 is configured as a computer 900 having a CPU 901, RAM 902, ROM 903, HDD 904, communication I / F 905, input / output I / F 906, and media I / F 907. The communication interface 905 is connected to an external communication device 915. The input / output interface 906 is connected to the input / output device 916. The media interface 907 reads and writes data to the recording medium 917. Furthermore, the CPU 901 controls each processing unit by executing a program (also called an application or app) loaded into the RAM 902. This program can also be distributed via a communication line or by recording it on a recording medium 917 such as a CD-ROM.

[0025] Figure 5 is a flowchart showing the processing of the switching calculator 10. This flowchart can be run once, or it can be run again whenever the demand forecast or production plan changes.

[0026] First, the date calculation unit 17 prepares various masters (item master 13, BOM master 12) (S101). Figure 6 is Table 13A, which shows the item master 13. Table 13A associates the item type, estimated delivery days, order lot number, and production lead time with the part indicated by the item code. This detailed information is referenced not only when calculating the changeover date but also when ordering the part.

[0027] Figure 7 is Table 12A, which shows the BOM master 12. Table 12A shows detailed information about the BOM tree, such as the pre-switchover BOM301, as explained in Figure 1. Table 12A associates the item number of each parent component's BOM (item code) with the information of its child components (item code, quantity used, effective start date, effective end date). For example, the parent component "SG001" is manufactured using one of each of the two child components "RM001" and "RM002". Also, with the switch from the old child component "RM002" to the new child component "RM003", the parent component "SG002" is manufactured using one of each of the two child components "RM001" and "RM003".

[0028] Returning to Figure 5, when the date calculation unit 17 receives a business requirement for a design change that will result in a parts change, it registers the information to that effect as follows (S102). • Register the item code of the parent part that uses the child part of the design change in the Change Master 11 (Figure 8). Also, register the initial switchover date, which is the date the design change was implemented. • Register the sub-components of the design change in table 12B of BOM master 12 (Figure 9), separating them into before and after the change (in the "before change" and "after change" columns of the detail number).

[0029] Figure 8 shows tables 11A and 11B representing the change master 11. Tables 11A and 11B each associate the change date of a child part with the item code of one or more parent parts that use the child part being changed, for each change number. In S102, table 11A registers the initial change number "CH001" for the two parent parts with item codes "SG001" and "SG002". In table 11B, an additional change number "CH002" is registered for the item code "SG003" of one parent part. Thus, even when switching the same child part, different change numbers may be registered depending on the parent part.

[0030] Figure 9 is Table 12B, which shows the BOM master 12. Table 12A in Figure 7 and Table 12B in Figure 9 share the same column items: "BOM, Item Number, Item Code, Quantity Used, Effective Start Date, Effective End Date." Furthermore, Table 12B has additional columns for the change number and the next change number to correspond to the change number in the change master 11 (Figure 8). For example, the parent part "SG001" will use child parts "RM001, RM002" until July 1, 2024, as the switchover date, and will use child parts "RM001, RM102" after the switchover date (as indicated by the "before change" line number). Also, the "next change number" in Table 12B indicates the change number assigned to the old child part, and the "change number" in Table 12B indicates the change number assigned to the new child part. The parts will be switched when the change numbers in both tables match.

[0031] The date calculation unit 17 calculates the quantity and date based on the increase / decrease events of each component (S103) by executing MRP 15 (Figure 10). Specifically, the date calculation unit 17 calculates the required number of products (parent components), the required number of their subordinate components (child components), and the required date. In the calculation of the required date, the date calculation unit 17 refers to table 13A in Figure 6 and works backward from the required date of the parent component, calculating the date on which the child component needs to be procured, based on the production lead time and the scheduled delivery date. Furthermore, in the calculation of the required quantity, the date calculation unit 17 refers to table 12A in Figure 7 and calculates (production quantity of parent component) × (number of child component used) = (required number of child component), and the order quantity takes into account the order lot.

[0032] Figure 10 is Table 15A, which shows the output data of MRP15. Table 15A manages the changes in the quantity of each part over time. Therefore, for each date, Table 15A associates the MRP element, which is an event at that date, with the inventory quantity change events corresponding to the MRP element (planned procurement, planned consumption), and the resulting inventory quantity reflecting those change events.

[0033] Then, the date calculation unit 17 runs a simulation using the results of MRP 15, which are based on the initial switching date registered in S102. As a result, the date calculation unit 17 updates the initial switching date to a highly accurate switching date that reflects the simulation results. Therefore, the date calculation unit 17 prompts the user to input various items via an input screen for simulating the calculation of the switching date (S110).

[0034] Figure 11 is a screen diagram showing the first example of an input screen. The input screen 210 has a simulation mode selection field 211 and a search condition input field 212. The simulation mode selection field 211 has radio buttons that allow the user to select one of the following two simulation modes in order to specify the calculation target for the switching date. • Specifying conditions by change number. This option is selected on input screen 210. This condition specification is primarily intended for cases where the user links design changes for the same project to a single change number. • Specifying conditions for the parts after the switch. This condition specification is primarily intended for cases where the user links design changes for the same project to multiple change numbers.

[0035] The search criteria input field 212 has text boxes for entering the following four search criteria, corresponding to the "Specify conditions by change number" selected in the simulation mode selection field 211. • "Plant" is the identifier of the BOM master 12 to be searched. • "Previous component" indicates the item code of the old sub-component that is being redesigned. • The "change number" is an identifier for the design change specified in the change master 11. Using the combination of the pre-switchover part and the change number as search criteria, the parent part subject to the calculation of the switchover date is searched from the BOM master 12. • The "target inventory quantity" is the target number of old sub-parts to be stored after the switchover date.

[0036] Figure 12 is a screenshot showing a second example of the input screen. The input screen 220 has a simulation mode selection field 221 and a search condition input field 222. The simulation mode selection field 221 has the same content as the simulation mode selection field 211, but "Specify conditions for the switched component" is selected. The search criteria input field 222 has text boxes for entering four search criteria corresponding to the "Specify conditions for parts after switching" selected in the simulation mode selection field 221. The plant, parts before switching, and target inventory quantity are as described in the search criteria input field 212. "Parts after changeover" indicates the item code of the new sub-part that will undergo a design change. Using the combination of parts before and after the changeover as search criteria, the parent part and change number subject to the calculation of the changeover date are retrieved from BOM Master 12.

[0037] Returning to Figure 5, the component identification unit 19 branches based on the simulation mode (condition specification) described in the simulation mode selection field 211 in Figure 11, which was entered in S110 (S111). First, if the change number specification is selected from the input device 21 in S111, the part identification unit 19 accepts the input of search conditions including the change number from the search condition input field 212 in the input screen 210 of Figure 11 (S112).

[0038] The part identification unit 19 obtains the parent part and the part data after the change (new child part) from the change number entered in S112 using the following [Procedure 1A] and [Procedure 2A] (S113). [Procedure 1A] From Table 12B of BOM Master 12 (Figure 9), search for rows of the old sub-components (before modification) using the following search conditions (AND condition). • Search criteria for S112: "Parts before switching" = "Item code" in Table 12B • The search condition "Change Number" in S112 = "Next Change Number" in Table 12B The search results row contains the "BOM" column (parent part) and the "item number" column.

[0039] [Procedure 2A] From Table 12B, search for rows of the new sub-part (after modification) using the following search conditions (AND condition). • The "Change Number" in the search criteria for S112 = the "Change Number" in Table 12B • The "BOM" obtained in step 1A = the "BOM" in table 12B • The "item number" obtained in step 1A = the "item number" in table 12B The "Item Code" column (new sub-parts) can be obtained from the rows of the search results.

[0040] For example, if the search conditions in S112 are given as "Part before switching = RM001" and "Change number = CH001", then in [Procedure 1A] of S113, the BOM of the parent part "SG001, SG002, SG004" will be found. Then, in [Procedure 1A] of S113, the new child parts corresponding to the parent parts BOM "SG001, SG002, SG004" are found to be new child parts "RM101" for parent parts "SG001, SG002" and new child part "RM102" for parent part "SG004". In this case, if multiple types of new child part "RM102" are found, the part identification unit 19 may display an error. Alternatively, the part identification unit 19 may narrow down the new child parts to one (for example, new child part "RM101" used for two parent parts) according to some rule (for example, majority vote).

[0041] Based on the above steps [1A] and [2A], the part identification unit 19 identifies the parent part and the child part after the switch from the BOM master 12 (parts management data) based on the child part before the switch and the change number specified in the switch instruction. Therefore, the change number is associated with the child part before and after the switch in the parts management data (Figure 9).

[0042] On the other hand, if the specified part after the switch is selected from the input device 21 in S111, the part identification unit 19 accepts the input of search conditions including the switched part from the search condition input field 222 in the input screen 220 of Figure 12 (S114). The part identification unit 19 obtains the parent part and change number from the switched part entered in S114 by following the steps [1B] and [2B] below (S115). [Procedure 1B] Search for rows of the old sub-components (before modification) in Table 12B using the following search criteria. • Search criteria for S114: "Parts before switching" = "Item code" in Table 12B (You may also add the simulation execution date to the search criteria.) The search results row contains the "BOM" column (parent part), the "item number" column, and the "next change number" column.

[0043] [Procedure 2B] From Table 12B, search for rows of the new sub-part (after modification) using the following search conditions (AND condition). • Search criteria for S114: "Parts after replacement" = "Item code" in Table 12B • The "BOM" obtained in step 1B = the "BOM" in table 12B • The "item number" obtained in step 1B = the "item number" in table 12B • The "next change number" obtained in step 1B = the "change number" in table 12B

[0044] For example, if the search conditions in S114 are given as "Part before switching = RM001" and "Part after switching = RM101", then in [Step 1B] of S115, the BOM of the parent part "SG001,SG002,SG003,SG004" will be found. Then, in [Step 2B] of S115, as the new child part corresponding to the parent part BOM "SG001,SG002,SG003,SG004" and "Item code = RM101", the new child part "RM101" will be found for the parent parts "SG001,SG002,SG003". Based on the above steps [1B] and [2B], the component identification unit 19 identifies the parent component from the component management data based on the child component before the switch specified in the switch instruction, and also identifies the child component after the switch instruction.

[0045] Here, during processing in S113 or S115, the part identification unit 19 determines in one of the following steps (S116): [Step 1A], [Step 2A], [Step 1B], or [Step 2B], whether or not data matching the search criteria exists in table 12B. If the result in S116 is No, the display control unit 18 displays an error message such as "No data matching the search criteria was found" (S117) and terminates the process. On the other hand, if the answer in S116 is Yes, the component identification unit 19 proceeds with processing from terminal A to Figure 13.

[0046] Figure 13 is a flowchart showing the processing performed by the switching calculation device 10, which is executed from terminal A in Figure 5. The date calculation unit 17 calculates the current number of available old sub-parts up to the target inventory level (S131) ​​based on the current inventory level (as of the flowchart execution date in Figure 13) and the confirmed future inventory levels for the old sub-parts. The available number of old sub-parts is the inventory level that can be consumed by the switchover date. Specifically, the date calculation unit 17 executes the following [Step 1C], [Step 2C], and [Step 3C]. [Procedure 1C] Obtain the current inventory quantity of the old sub-components from the inventory management unit 16.

[0047] [Procedure 2C] Obtain the future confirmed inventory quantity of the old sub-components from MRP15. The future confirmed inventory quantity is the number of units that have already been ordered from the supplier and are confirmed to become inventory. The date on which the future confirmed inventory will be received is also kept. If there are multiple dates on which the confirmed inventory will be received, the most recent date is kept. In the case of Figure 10, "200 units from the purchase order on 2024 / 6 / 15" (planned procurement) is included in the future confirmed inventory quantity (inventory), but "200 units from the purchase plan on 2024 / 6 / 22 (not yet ordered)" (planned procurement) is not included in the future confirmed inventory quantity (inventory).

[0048] [Step 3C] The calculation is performed as follows: (Current inventory quantity from [Step 1C]) + (Future confirmed incoming quantity from [Step 2C]) - (Target inventory quantity entered on input screen 210 in Figure 11 or input screen 220 in Figure 12) = (Available quantity of old sub-parts). By adding the future confirmed incoming quantity from [Step 2C], the date calculation unit 17 increases the inventory quantity of sub-parts according to the procurement plan for sub-parts.

[0049] Figure 14 is Table 17A, which shows the calculation process data (details of S131) ​​of the date calculation unit 17. Table 17A manages the changes in the quantity of each old sub-component over time. In Tables 15A and 17A, the MRP elements and planned consumption have the same meaning. The inventory quantity in Table 15A is replaced by the available quantity in Table 17A. The inventory quantity in Table 15A shows the inventory quantity at the present time (the corresponding date). On the other hand, the available quantity in Table 17A is (the current inventory quantity in [Step 1C]) + (the future confirmed incoming quantity in [Step 2C]). Therefore, in Table 17A, the events to be procured from the records in Table 15A are pre-assigned in the "Available Quantity" column, so only the remaining events to be consumed are listed.

[0050] Returning to Figure 13, the date calculation unit 17 determines whether the number of available items calculated in S131 is less than 0 (S132). If the answer in S132 is Yes, the display control unit 18 displays an error such as "Insufficient old sub-components" on the display device 22 (S133). If the answer in S132 is No, the date calculation unit 17 extracts the planned consumption of old sub-components obtained from MRP 15 and executes a loop to select the extracted results in chronological order (oldest first) (S141~S145). The date calculation unit 17 subtracts the planned consumption selected in the loop from the number of available old sub-components (S142). The date calculation unit 17 determines whether the number of available old child components as a result of the subtraction in S142 is 0 or less (S143). If the answer in S143 is Yes, the date calculation unit 17 sets the switchover date from the current scheduled consumption date selected in the loop as follows (S144). If (the number of available sub-parts from the old inventory) = 0, the switchover date is the day after the planned consumption date. In other words, the date calculation unit 17 sets the switchover date to the day after the expected date when the inventory of sub-parts will equal the target inventory. If (the number of available sub-components from the old system) < 0, the switchover date is the planned consumption date for the current system. In other words, the date calculation unit 17 sets the switchover date to the expected date on which the inventory of sub-components transitions from a state where it exceeds the target inventory to a state where it falls below the target inventory.

[0051] If S144 is not executed at the end of the loop in S145, it means that there are still surplus old sub-parts even after the initial switchover date has passed. In that case, as shown in S151 to S155 below, the old sub-parts are used as substitutes to reduce the inventory of old sub-parts. The date calculation unit 17 extracts the planned consumption of new components obtained from the MRP 15 and executes a loop to select the extracted results in chronological order (oldest first) (S151~S155).

[0052] The date calculation unit 17 subtracts the planned consumption of the new sub-components selected in the loop of S151 from the number of available old sub-components (S152). The date calculation unit 17 determines whether the number of available old child components, which is the result of the subtraction in S152, is 0 or less (S153). If the answer in S153 is Yes, the date calculation unit 17 sets the switchover date from the current scheduled consumption date selected in the loop in S151 as follows (S154). • If (Number of available old sub-components) = 0, the switchover date = the day after the scheduled consumption date. • If (number of available old sub-components) < 0, the switchover date = the planned consumption date for this time. As a result, the date calculation unit 17 reduces the inventory of sub-components by, up to the initial scheduled switchover date, reducing the inventory of sub-components before the switchover according to the planned consumption of the sub-components before the switchover (S141-S145). Furthermore, after the initial scheduled switchover date, the date calculation unit 17 reduces the inventory of sub-components before the switchover according to the planned consumption of the sub-components after the switchover (S151-S155).

[0053] Furthermore, if S154 is not executed at the end of the S155 loop, then even after taking into account the planned consumption of new sub-components after the initial switchover date, there will still be a surplus of old sub-components. In that case, the date calculation unit 17 sets the planned consumption date of the new sub-component last selected in the loop of S151 (i.e., the latest planned consumption date of the new sub-component) as the provisional switchover date (S161). Then, the date calculation unit 17 proceeds with processing from terminal B to Figure 15.

[0054] Figure 15 is a flowchart showing the processing performed by the switching calculation device 10, which is executed from terminal B in Figure 13. The date calculation unit 17 determines whether or not an event related to the procurement of the old sub-component will occur after the switching date set in S144, S154, or S161 (S171). If the answer to S171 is Yes, the display control unit 18 displays an error message such as "There is an excess inventory of old sub-components after the switchover" on the display device 22 (S173). If the answer to S171 is No, the date calculation unit 17 displays the date of the calculation result and its calculation process (table 17A) on the screen, as shown in the output screen 230 of Figure 16 (S172).

[0055] Figure 16 is a screenshot showing the simulation results display screen. The output screen 230 displayed in S172 includes a search criteria display field 231, a display field 232 for the calculated switching date, and a display table 233 for the calculation process of the switching date. The search criteria display field 231 displays the data entered in the search criteria input field 212 or the data entered in the search criteria input field 222 as is. The display field 232 for the switching date shows the switching date, which is the result of the date calculation unit 17's calculation based on the input data displayed in the search criteria display field 231. The display table 233 associates the item code of the old sub-part that is being redesigned with events indicating changes in the inventory quantity of the old sub-part (required date, procurement / consumption, details, and quantity), as part of the calculation process of the date calculation unit 17, and the available quantity reflecting those events.

[0056] For example, we will explain how to switch from the old sub-part's item code "RM001" to the new sub-part's item code "RM101" according to the search criteria display field 231. As of May 27, 2024, the inventory of old sub-parts is 180 units (target inventory "80" + available quantity "100"). In other words, the available quantity is the current inventory minus the target inventory, and the first day the available quantity falls below 0 will be considered the switchover date. Subsequently, events that consume old sub-parts will occur on June 3, 2024, June 20, 2024, July 12, 2024, and July 15, 2024.

[0057] Then, since the number of available slots will become less than 0 from 2024 / 7 / 15, the date calculation unit 17 outputs 2024 / 7 / 15 as the transition date in the transition date display field 232. Note that the required dates "2024 / 7 / 12" and "2024 / 7 / 15" in display table 233 have the corresponding item code as the new sub-part item code "RM101". This display is because the system switch date (at the time of execution) before recalculation using the running change method was 2024 / 6 / 30, and the item code remained switched to the new sub-part from the following day onward.

[0058] The following examples illustrate the calculation process data of the date calculation unit 17 in various cases, referring to Figures 17 to 21. These examples assume the following: • Original switchover date = 2024 / 7 / 1 • Initial stock quantity (as of May 1, 2024) = 300 • Target inventory = 50 (Figures 17-20) or Target inventory = 450 (Figure 21) • Inventory (as of the date) = Available quantity + 50

[0059] Figure 17 is Table 401, which shows the calculation process data of the date calculation unit 17 when the switchover date is brought forward due to the number of available slots becoming 0. In Table 401, the number of available items as of 2024 / 5 / 1 is 250, which becomes 0 on 2024 / 6 / 20 (Yes in S143). Therefore, as explained in S144, the switchover date is the day after the current planned consumption date, so the date calculation unit 17 sets 2024 / 6 / 21 as the new switchover date. This allows us to use up the old components while maintaining the target inventory level. Furthermore, the new components can be introduced into production earlier than the initially planned switchover date.

[0060] Figure 18 is Table 402, which shows the calculation process data of the date calculation unit 17 when the switchover date is brought forward due to the number of available slots falling below 0. In Table 402, the number of available items as of 2024 / 5 / 1 is 250, which will become less than 0 on 2024 / 6 / 15 (Yes in S143). Therefore, as explained in S144, the switchover date is the same day as the planned consumption date, so the date calculation unit 17 sets 2024 / 6 / 15 as the new switchover date. This allows us to use up the old components while maintaining the target inventory level. Furthermore, the new components can be introduced into production earlier than the initially planned switchover date.

[0061] Figure 19 is Table 403, which shows the calculation process data of the date calculation unit 17 when the switchover date is postponed because the number of available slots exceeds 0 even after the initial switchover date has passed. Table 403 shows that the number of available old sub-parts "RM001" as of 2024 / 5 / 1 was 250, but even after the initial switchover date of 2024 / 7 / 1, it was still 100, meaning it was in a state of exceeding 0. In this case, as explained in S151~S155, the date calculation unit 17 reduces the inventory of old sub-parts by having the old sub-parts "RM001" consumed as a substitute for the new sub-parts "RM101" which are scheduled to be consumed on 2024 / 7 / 3, 2024 / 7, 2024 / 8. As a result, the number of available slots as of 7 / 1 / 2024 = 50 becomes less than 0 on 7 / 8 / 2024 (Yes in S153). Therefore, as explained in S154, the switchover date is the same day as the planned consumption date, so the date calculation unit 17 sets 7 / 8 / 2024 as the new switchover date. This allows the planned consumption of new sub-components to be used in calculating the switchover date for old sub-components, enabling the old sub-components to be used up while maintaining the target inventory level.

[0062] Figure 20 is Table 404, which shows the calculation process data of the date calculation unit 17 when the number of available slots increases after the switchover date has been determined. In Table 404, the number of available items as of 2024 / 5 / 1 is 250, which will become less than 0 on 2024 / 6 / 1 (Yes in S143). Therefore, as explained in S144, the switchover date is the same day as the planned consumption date, so the date calculation unit 17 sets 2024 / 6 / 1 as the new switchover date. However, due to the subsequent procurement schedule for June 15, 2024 (+100) (Yes in S171), the number of available parts has increased retrospectively, and since this is after the switchover date, further consumption of the old sub-components is not expected. In this case, the display control unit 18 displays an error message on the display device 22 such as, "Due to the procurement schedule (+100) for June 15, 2024, following the switchover on June 1, 2024, there is an excess inventory of the old sub-components. We recommend canceling this procurement schedule (+100) or doing it before June 1, 2024." (S173). In other words, if the inventory of sub-components increases according to the procurement plan for sub-components that is later than the predicted switchover date, the date calculation unit 17 displays an error from the display control unit 18 indicating that the inventory is excessive.

[0063] Figure 21 is Table 405, which shows the calculation process data of the date calculation unit 17. In Figures 17-20, the target inventory quantity was set to 50, but in Figure 21, the target inventory quantity is set to 450. In this case, with an initial inventory quantity of 300 in Table 405, the target inventory quantity has not been secured as of the current date (May 1, 2024), so the available quantity is less than 0 (Yes in S132). Therefore, the display control unit 18 displays an error message on the display device 22, such as "There is a shortage of old sub-components. We recommend procuring additional old sub-components until the inventory reaches the target inventory level." (S133). In other words, if the target inventory quantity of sub-components exceeds the actual inventory quantity of sub-components from the outset, the date calculation unit 17 displays an error from the display control unit 18 indicating that there is a shortage of sub-components.

[0064] The production management system 100 of this embodiment, as described above, has the following main features. The input device 21 specifies the design change to be calculated on the input screen 210 in Figure 11 or the input screen 220 in Figure 12. Two patterns of specification methods are available (specified change number or part code after switching). The date calculation unit 17 refers to the inventory requirements information (Table 15A in Figure 10), which is the result of the MRP 15's deployment at the time of execution, and simulates the switchover date based on the inventory and planned consumption at each date (Table 17A in Figure 14). The display control unit 18 provides the user with information about the date of the switch from the old sub-component to the new sub-component by displaying the output screen 230 of Figure 16 on the display device 22.

[0065] Furthermore, the present invention is not limited to the embodiments described above, and it goes without saying that various other applications and modifications can be taken as long as they do not depart from the gist of the invention as described in the claims. For example, the embodiments described above describe the configuration of the production management system 100 in detail and specifically in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those that include all the components described. Also, it is possible to replace a part of the configuration of one embodiment with a component of another embodiment. It is also possible to add a component of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, replace, or delete other components for a part of the configuration of each embodiment.

[0066] Furthermore, some or all of the above configurations, functions, and processing units may be implemented in hardware, for example, by designing them as integrated circuits. Broadly defined processor devices such as FPGAs (Field Programmable Gate Arrays) and ASICs (Application Specific Integrated Circuits) may be used as hardware. Furthermore, each component of the production management system 100 according to the above-described embodiment may be implemented on any hardware, as long as the respective hardware can send and receive information from each other via a network. Also, the processing performed by a certain processing unit may be implemented by a single piece of hardware, or by distributed processing using multiple pieces of hardware. [Explanation of Symbols]

[0067] 10 Switching Calculation Device 11 Change Master 12. BOM Master (Parts Management Data) 13 Item Master 14. Production Planning System 15 MRP 16. Inventory Management Department 17 Date Calculation Unit 18 Display Control Unit 19. Part Identification Section 22 Display device 21 Input device 100 Production Management Systems

Claims

1. The switching calculation device has a component identification unit, a date calculation unit, and a display control unit. The aforementioned part identification unit refers to part management data that associates the parent part to be produced with one or more child parts used in the production of that parent part, and identifies the parent part that uses the child part specified in the switching instruction before the switching. The date calculation unit reduces the inventory of child parts that are scheduled to be consumed according to the production plan of the parent parts identified by the part identification unit, and predicts the changeover date on which the inventory of those child parts will reach the target inventory number specified in the changeover instruction. The display control unit is characterized by displaying the switching date predicted by the date calculation unit. Switching calculation method.

2. The date calculation unit is characterized in that, when the target inventory quantity specified in the switching instruction is 0, it predicts the switching date on which the inventory quantity of sub-components will become 0. The switching calculation method according to claim 1.

3. The date calculation unit is characterized by increasing the inventory of sub-components in accordance with the procurement plan for sub-components. The switching calculation method according to claim 1.

4. The aforementioned parts management data associates change numbers with the sub-components before and after the changeover. The component identification unit is characterized by identifying the parent component and the child component after the switch from the component management data based on the child component before the switch and the change number specified in the switch instruction. The switching calculation method according to claim 1.

5. The component identification unit is characterized by identifying the parent component from the component management data based on the child component before the switch specified in the switch instruction, and identifying the child component after the switch in response to the switch instruction. The switching calculation method according to claim 1.

6. The date calculation unit is characterized in that it sets the day following the expected date on which the inventory of sub-components becomes equal to the target inventory as the changeover date. The switching calculation method according to claim 1.

7. The date calculation unit is characterized in that the expected date on which the inventory of sub-components transitions from a state where the inventory exceeds the target inventory to a state where the inventory falls below the target inventory is set as the transition date. The switching calculation method according to claim 1.

8. The date calculation unit is characterized in that, as a process for reducing the inventory of sub-components, it reduces the inventory of sub-components before the switchover in accordance with the planned consumption of sub-components before the switchover until before the initial scheduled switchover date, and after the initial scheduled switchover date, it reduces the inventory of sub-components before the switchover in accordance with the planned consumption of sub-components after the switchover. The switching calculation method according to claim 1.

9. The date calculation unit is characterized in that, if the inventory of sub-components increases according to the procurement plan for sub-components that is later than the predicted switchover date, the display control unit will display an error indicating that the inventory is excessive. The switching calculation method according to claim 3.

10. The date calculation unit is characterized in that, if the target inventory quantity of sub-components exceeds the actual inventory quantity of sub-components from the outset, the display control unit displays an error indicating a shortage of sub-components. The switching calculation method according to claim 1.

11. A parts identification unit identifies a parent part that uses a pre-switching child part specified in a switchover instruction by referring to parts management data that associates a parent part to be produced with one or more child parts used in the production of that parent part, A date calculation unit reduces the inventory of child parts that are scheduled to be consumed according to the production plan of the parent parts identified by the aforementioned parts identification unit, and predicts the switching date on which the inventory of those child parts will reach the target inventory number specified in the switching instruction. The system is characterized by having a display control unit that displays the switching date predicted by the date calculation unit. Switching calculator.

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