JP6278867B2 - Appropriate inventory calculation device, appropriate inventory calculation method and program - Google Patents

Description

  The present invention relates to an appropriate inventory quantity calculation device, an appropriate inventory quantity calculation method, and a program for calculating an appropriate inventory quantity of components and the like.

  Technology for calculating the inventory level of parts, etc., technology that determines the amount of inventory based on specific conditions such as demand fluctuation and procurement lead time, technology that adds shortage to inventory from demand forecast and production plan, and procurement lead time is short For example, there is a technology that adds the difference quantity between ordering and delivery to the safety stock for the number of days of procurement.

  In Patent Document 1, assuming an increase in sales fluctuation that exceeds the initial sales fluctuation assumed at the beginning, the demand forecast in the remaining life cycle of the product is performed, and the number of lots ordered for dedicated parts, Simulates a supply chain model that includes the material unit price and delivery lead time based on the number of lots, and does not cause product shortages during expanded sales fluctuations, and minimizes the disposal loss of dedicated materials at the end of life (EOL). A supply chain efficiency support method for calculating the safety stock number and procurement conditions of dedicated materials is disclosed.

  Patent Document 2 discloses a safety stock quantity calculation method for calculating an appropriate safety stock quantity based on a demand forecast and demand safety coefficient calculated on the demand side, and a supply schedule and supply safety coefficient calculated on the supply side. Has been.

  In Patent Document 3, a production plan simulation is executed to generate production plan data including a production plan amount and a production shortage amount for each part number corresponding to the number of trials, and statistically process all the production shortage amounts as necessary inventory amounts. An appropriate inventory quantity calculation method for determining an appropriate inventory quantity for each product number based on a preset inventory management standard is disclosed.

  In Patent Document 4, a corrected safety stock quantity is calculated using an error rate, a demand forecast value, and a monetary band index that become negative when the order requirement amount increases, and the minimum safety stock quantity calculated using the demand forecast value In addition, an inventory management system that calculates a fixed safety stock amount by adding the calculated corrected safety stock amount is disclosed.

  In Patent Document 5, the actual number of arrivals with respect to the expected arrival number of products is stored for each day, and the difference value between the expected arrival number and the actual arrival number is calculated as a first difference value for each day within the evaluation period. The process of calculating the value obtained by adding the difference value for the number of procurement days as the first cumulative difference is executed for each day in the evaluation period, and the average value and the standard deviation value of the first cumulative difference for each day in the evaluation period And a safety stock quantity calculation system that calculates the safety stock quantity of a product with respect to arrival delay using the calculated average value and standard deviation value of the first cumulative difference.

JP 2009-301466 A JP 09-062941 A JP 2004-118429 A JP 2009-143660 A JP 2009-173435 A

  In the supply and demand of inventory, while it is necessary to prevent shortage and maintain supply and demand reliability for payout requests, optimization of inventory (reduction of inventory) is required.

  In particular, maintenance service parts and the like have become obsolete, supply reliability indicating the ratio of the number of parts delivered to the number of parts ordered for delivery is reduced, and the procurement lead time tends to be prolonged.

  In reality, there is no theory for calculating an appropriate safety stock quantity for such parts, and the stock quantity is determined based on the intuition and experience of the person in charge. As a result, parts could not be supplied due to shortage of inventory (out of stock), resulting in product delays and excessive inventory.

  In the techniques of Patent Documents 1 to 5, it is possible to calculate an appropriate inventory amount according to the supply reliability in the case of maintenance service parts (when the supply reliability of the delivery deadline is low and the delivery time is extended). Can not.

  The present invention has been made in view of the circumstances as described above, and it is possible to achieve both prevention of shortage of inventory and suppression of increase in inventory even for parts and the like that have low delivery reliability for delivery deadlines and have long delivery times. The purpose is to.

  In order to achieve the above object, an appropriate inventory amount calculation apparatus according to the present invention includes an input unit, a storage unit, an acquisition unit, a first calculation unit, a second calculation unit, a third calculation unit, and a generation unit. And an output unit. The input unit obtains target value information indicating a target value of supply reliability indicating a ratio of the number of deliveries to the number of orders of the object. The storage unit stores delivery result information of parts delivered in the past. The acquisition unit acquires information indicating the production interval stock quantity and the safety stock quantity of the object. The first calculation unit calculates supply reliability before and after the delivery deadline of the object based on the delivery result information of the object. The second calculation unit calculates the number of days required to reach the target value indicated by the target value information based on the supply reliability calculated by the first calculation unit. The third calculation unit calculates the delay interval inventory amount and the delayed safety inventory amount using the number of days required to reach the target value calculated by the second calculation unit. The generation unit adds the delay interval stock amount and the delayed safety stock amount to the production interval stock amount and the safety stock amount, calculates an appropriate stock amount, and generates appropriate stock amount information indicating the appropriate stock amount. The output unit outputs appropriate inventory information.

  According to the present invention, by calculating an appropriate stock quantity according to the supply reliability, it is possible to prevent shortage of inventory and suppress increase in inventory even for parts with low delivery reliability due to delivery deadlines and longer delivery times. Can be compatible.

It is a figure which shows the structural example of the appropriate stock quantity calculation apparatus which concerns on embodiment of this invention. It is a figure which shows the example of the delivery performance information which concerns on embodiment. It is a figure showing the relationship between the difference days from the delivery deadline of the components which concern on embodiment, and supply reliability. It is a figure which shows the appropriate stock quantity which concerns on embodiment. It is a flowchart which shows an example of operation | movement of the appropriate stock quantity calculation process which concerns on embodiment. It is a block diagram which shows an example of the hardware constitutions of the appropriate stock quantity calculation apparatus which concerns on embodiment.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail with reference to drawings. In addition, the same code | symbol is attached | subjected to the part which is the same or it corresponds in a figure. In the present embodiment, a case will be described in which an appropriate inventory amount of parts is calculated.

  FIG. 1 is a diagram illustrating a configuration example of an appropriate inventory amount calculation apparatus according to an embodiment of the present invention. The appropriate inventory amount calculation device 1 includes an input unit 11, a storage unit 12, a calculation unit 13, and an output unit 14.

  The input unit 11 receives an input of a target value of supply reliability of the target part by the user, and acquires target value information indicating the input target value. Note that the input unit 11 may acquire target value information indicating the target value input by the user from the outside. The input unit 11 sends the acquired target value information to the calculation unit 13.

  The storage unit 12 stores delivery result information of parts delivered in the past.

  FIG. 2 is a diagram illustrating an example of delivery result information according to the embodiment. The delivery result information is stored for each part, and the example of FIG. 2 is the delivery result information in 2013 for the part having the part ID 0001 for identifying the part.

  The delivery record information indicates the “delivery date” indicating the delivery deadline, the “delivery date” indicating the actual delivery date, the “number of orders” indicating the number of orders, and the number of deliveries delivered on the delivery date. Includes item with "Number of deliveries".

  Based on the target value indicated by the target value information received from the input unit 11, the calculation unit 13 calculates an appropriate inventory amount from the delivery result information of the target part stored in the storage unit 12.

  Hereinafter, a method for calculating the appropriate inventory amount will be described.

  The calculation unit 13 calculates the production interval inventory expressed by the equation shown in Equation 1.

  O is the ordering cycle expressed in unit periods (for example, days), and D is the average number of goods issued per unit period. If the delivery date is constant and there is no change in the quantity issued, if the production interval stock quantity is ordered for each ordering cycle, the inventory for the quantity delivered last time is just before the order quantity (production interval inventory quantity) is delivered. 0.

  Based on this production interval stock quantity, an appropriate stock quantity is calculated by adding the amount satisfying the target supply reliability from the fluctuations in the number of deliveries, the delivery times of the ordered items, and the fluctuations in the number of deliveries.

The calculation unit 13 calculates the safety stock amount expressed by the equation shown in Equation 2. The safety stock quantity is an inventory quantity that has a probability that the stock cannot be delivered due to the stock being out of stock even if the number of shipments fluctuates. The safety factor is set so that the probability of delivery failure being below the standard.

  α is a safety factor, σ is the standard deviation of the number of issues, and T is the lead time.

  The calculation formula for calculating the production interval stock quantity and the safety stock quantity of the target part is not limited to this, and an existing calculation formula may be used. Moreover, the calculation part 13 may acquire the information which shows the production interval stock quantity and safety stock quantity of an object part from the outside, and the memory | storage part 12 may memorize | store beforehand.

  When the calculation unit 13 receives the target value information from the input unit 11, the calculation unit 13 calls the delivery result information of the target part stored in the storage unit 12. The calculation unit 13 calculates supply reliability before and after the delivery deadline of the target part from the called delivery result information.

  Supply reliability is calculated by the formula of number of deliveries / number of orders × 100 (%) for each difference days from the delivery deadline. For example, when calculated from the delivery record information for one year shown in FIG. 2, the supply reliability one day before the delivery deadline is 300/1200 × 100 = 25 (%). Supply reliability one day after the delivery deadline is 900/1200 × 100 = 75 (%).

  FIG. 3 is a diagram illustrating the relationship between the difference days from the delivery deadline of parts and the supply reliability according to the embodiment.

  In the example of FIG. 3, the calculation unit 13 calculates the supply reliability of the target parts from n−3 days to n + 8 days, where n is the delivery deadline. For example, when the target value indicated by the target value information has a supply reliability of 90%, since it has reached 90% in n + 5 days, the calculation unit 13 reaches the supply reliability of 90%, which is the target value. The number of days required for N = 5 is calculated.

  The calculating unit 13 calculates the delay interval stock quantity and the delayed safety stock quantity using the number of days N required to reach the target value.

  The calculation unit 13 calculates the delay interval stock quantity expressed by the equation shown in Equation 3.

  If there is no change in the delivery quantity, the delay interval stock quantity becomes 0 during the period N from the delivery deadline until the supply reliability reaches the target value.

The calculation unit 13 calculates the delayed safety stock amount expressed by the equation shown in Equation 4.

  Delayed safety stock is the amount of stock whose probability of being out of stock and unable to deliver during the period N from the delivery deadline until the supply reliability reaches the target value, even if the number of shipments fluctuates. is there.

  In Equation 4, the safety factor α is used as in the case of the safety stock quantity. However, the safety factor may be adjusted in consideration of the fluctuation of the number of days N, and a correction factor is further added to the safety factor α. You may multiply.

  The calculation unit 13 adds the delay interval stock amount and the delayed safety stock amount to the production interval stock amount and the safety stock amount, and calculates an appropriate stock amount of the target part.

  FIG. 4 is a diagram illustrating an appropriate inventory amount according to the embodiment. In the example of FIG. 4, the graph L with the vertical axis representing inventory quantity and the horizontal axis representing time represents the change in inventory quantity of the target part. When the target parts are delivered within the delivery deadline, the stock quantity increases by a certain amount (the number of orders) and gradually decreases as the target parts are supplied to the site.

  However, the delivery date is not always the delivery deadline. If the delivery date follows the normal distribution G as shown in the figure, when the target part is delivered after the delivery deadline, there is a risk that the production interval stock quantity and the safety stock quantity are used up and the target part cannot be supplied to the site. .

  Therefore, as described above, the delay interval stock amount and the delayed safety stock amount taking into account the supply reliability of the target part are calculated and added to the production interval stock amount and the safety stock amount to obtain an appropriate stock amount.

  Returning to FIG. 1, the calculation unit 13 of the appropriate inventory quantity calculation device 1 generates appropriate inventory quantity information indicating the calculated appropriate inventory quantity and sends it to the output unit 14. The output unit 14 outputs appropriate inventory information. The output method may be screen display, audio output, or email transmission to the user's terminal.

  FIG. 5 is a flowchart illustrating an example of the operation of the appropriate inventory amount calculation process according to the embodiment. The appropriate inventory quantity calculation process starts when the appropriate inventory quantity calculation device 1 is turned on.

  When the input unit 11 of the appropriate inventory quantity calculation device 1 does not acquire target value information (step S11; NO), step S11 is repeated to wait for acquisition of target value information.

  When the input unit 11 acquires target value information (step S11; YES), the target value information is sent to the calculation unit 13.

  The calculation unit 13 calculates the production interval stock quantity of the target part (step S12). The calculation unit 13 calculates the safety stock amount of the target part (step S13).

  The calculation unit 13 calculates the number of days N required to reach the target value based on the target value indicated by the target value information received from the input unit 11 (step S14).

  The calculation unit 13 calculates the delay interval inventory amount using the number of days N required to reach the target value (step S15). The calculation unit 13 calculates the delayed safety stock quantity using the number of days N required to reach the target value (step S16).

  The calculation unit 13 calculates an appropriate inventory quantity obtained by adding the delay interval inventory quantity and the delayed safety inventory quantity to the production interval inventory quantity and the safety inventory quantity (step S17).

  The calculator 13 generates appropriate inventory information indicating the appropriate inventory (step S18) and sends it to the output unit 14. The output unit 14 outputs appropriate inventory information (step S19).

  If the power of the appropriate inventory amount calculation device 1 is not turned off (step S20; NO), the process returns to step S11, and steps S11 to S20 are repeated. If the power is turned off (step S20; YES), the process is terminated.

  As described above, according to the appropriate inventory amount calculation apparatus 1 of the present embodiment, by calculating the appropriate inventory amount according to the supply reliability, the supply reliability of the delivery deadline is low and the long delivery time is extended. Even with such parts, it is possible to achieve both prevention of inventory shortage and suppression of inventory increase. In addition, the appropriate inventory amount calculated according to the supply reliability can be used as a judgment criterion for inventory shortage or excess inventory.

  FIG. 6 is a block diagram illustrating an example of a hardware configuration of the appropriate inventory amount calculation apparatus according to the embodiment. As shown in FIG. 6, the appropriate inventory amount calculation apparatus 1 includes a control unit 51, a main storage unit 52, an external storage unit 53, an operation unit 54, a display unit 55, and a transmission / reception unit 56. The main storage unit 52, the external storage unit 53, the operation unit 54, the display unit 55, and the transmission / reception unit 56 are all connected to the control unit 51 via the internal bus 50.

  The control unit 51 includes a CPU (Central Processing Unit) and the like, and in accordance with a control program 59 stored in the external storage unit 53, each process of the input unit 11, the calculation unit 13, and the output unit 14 of the appropriate inventory amount calculation device 1 is performed. Execute.

  The main storage unit 52 is composed of a RAM (Random-Access Memory) or the like, loads a control program 59 stored in the external storage unit 53, and is used as a work area of the control unit 51.

  The external storage unit 53 includes a nonvolatile memory such as a flash memory, a hard disk, a DVD-RAM, and a DVD-RW, and stores in advance a program for causing the control unit 51 to perform the process of the appropriate inventory amount calculation device 1. Further, in accordance with an instruction from the control unit 51, the data stored in the program is supplied to the control unit 51, and the data supplied from the control unit 51 is stored. The storage unit 12 is configured in the external storage unit 53.

  The operation unit 54 includes a pointing device such as a keyboard and a mouse, and an interface device that connects the keyboard and the pointing device to the internal bus 50. The input information is supplied to the control unit 51 via the operation unit 54. The operation unit 54 functions as the input unit 11.

  The display unit 55 is composed of a CRT or LCD. When the appropriate inventory quantity calculation device 1 displays the appropriate inventory quantity information on the screen, the operation unit 54 functions as the output unit 14.

  The transmission / reception unit 56 includes a network termination device or wireless communication device connected to the network, and a serial interface or LAN (Local Area Network) interface connected to them. When the appropriate inventory amount calculation apparatus 1 acquires target value information from the outside, the transmission / reception unit 56 functions as the input unit 11. When the appropriate inventory quantity calculation device 1 transmits the appropriate inventory quantity information to the user's terminal by mail, the transmission / reception unit 56 functions as the output unit 14.

  The processing of the input unit 11, the storage unit 12, the calculation unit 13, and the output unit 14 of the appropriate inventory amount calculation apparatus 1 shown in FIG. 1 is performed by the control program 59, the control unit 51, the main storage unit 52, the external storage unit 53, and the operation. The processing is executed by using the unit 54, the display unit 55, the transmission / reception unit 56, and the like as resources.

  In addition, the hardware configuration and the flowchart described above are merely examples, and can be arbitrarily changed and modified.

  The central part that performs the processing of the appropriate inventory quantity calculation device 1 including the control unit 51, the main storage unit 52, the external storage unit 53, the operation unit 54, the display unit 55, the transmission / reception unit 56, the internal bus 50, It can be realized by using a normal computer system regardless of a dedicated system. For example, a computer program for executing the above operation is stored and distributed on a computer-readable recording medium (flexible disk, CD-ROM, DVD-ROM, etc.), and the computer program is installed in the computer. Accordingly, the appropriate inventory amount calculation apparatus 1 that executes the above-described processing may be configured. Further, the appropriate inventory amount calculation apparatus 1 may be configured by storing the computer program in a storage device included in a server device on a communication network such as the Internet and downloading the normal computer system.

  Further, when the function of the appropriate inventory amount calculation device 1 is realized by sharing of an OS (operating system) and an application program, or by cooperation between the OS and the application program, only the application program portion is recorded on a recording medium or a storage device. May be stored.

  It is also possible to superimpose a computer program on a carrier wave and provide it via a communication network. For example, the computer program may be posted on a bulletin board (BBS, Bulletin Board System) on a communication network, and the computer program may be provided via the network. The computer program may be started and executed in the same manner as other application programs under the control of the OS, so that the above-described processing may be executed.

  DESCRIPTION OF SYMBOLS 1 Appropriate inventory calculation apparatus, 11 Input part, 12 Storage part, 13 Calculation part, 14 Output part, 50 Internal bus, 51 Control part, 52 Main storage part, 53 External storage part, 54 Operation part, 55 Display part, 56 Transmitter / receiver, 59 control program.

Claims (4)

An input unit for acquiring target value information indicating a target value of supply reliability indicating the ratio of the number of deliveries to the number of orders of the object;
A storage unit for storing the delivery result information of parts delivered in the past;
An acquisition unit for acquiring information indicating a production interval stock quantity and a safety stock quantity of the object;
A first calculation unit that calculates the supply reliability before and after the delivery deadline of the object based on the delivery result information of the object;
A second calculator that calculates the number of days required to reach the target value indicated by the target value information based on the supply reliability calculated by the first calculator;
A third calculation unit that calculates a delay interval inventory amount and a delayed safety stock amount using the number of days required to reach the target value calculated by the second calculation unit;
A generation unit that calculates an appropriate inventory quantity by adding the delayed interval inventory quantity and the delayed safety inventory quantity to the production interval inventory quantity and the safety inventory quantity, and generates appropriate inventory quantity information indicating the appropriate inventory quantity;
An output unit for outputting the appropriate inventory amount information;
An appropriate inventory amount calculation device.   The third calculation unit calculates the delay interval inventory quantity based on the number of days required to reach the target value and the average delivery quantity of the object, and the delayed safety inventory quantity is calculated based on the safety of the object. The appropriate inventory amount calculation device according to claim 1, wherein calculation is performed based on a coefficient, a standard deviation of the number of issues of the object, and a number of days required to reach the target value. An input step for obtaining target value information indicating a target value of supply reliability indicating a ratio of the number of deliveries with respect to the number of orders of the object, which is executed by an appropriate inventory quantity calculation device that stores delivery result information of parts delivered in the past; ,
An acquisition step of acquiring information indicating a production interval stock quantity and a safety stock quantity of the object;
A first calculation step of calculating the supply reliability before and after the delivery deadline of the object based on the delivery result information of the object;
A second calculation step for calculating the number of days required to reach the target value indicated by the target value information based on the supply reliability calculated in the first calculation step;
A third calculation step of calculating a delay interval stock quantity and a delayed safety stock quantity using the number of days required to reach the target value calculated in the second calculation step;
Generating the appropriate inventory quantity by calculating the appropriate inventory quantity by adding the delayed interval inventory quantity and the delayed safety inventory quantity to the production interval inventory quantity and the safety inventory quantity; and generating the appropriate inventory quantity information indicating the appropriate inventory quantity;
An output step of outputting the appropriate inventory quantity information;
An appropriate inventory amount calculation method comprising: An input step for obtaining target value information indicating a target value of supply reliability indicating a ratio of the number of deliveries with respect to the number of orders of an object to a computer;
An obtaining step for obtaining information indicating a production interval stock quantity and a safety stock quantity of the object;
A first calculation step of calculating the supply reliability before and after the delivery deadline of the object based on the delivery result information of the object delivered in the past;
A second calculation step of calculating the number of days required to reach the target value indicated by the target value information based on the supply reliability calculated in the first calculation step;
A third calculation step for calculating a delay interval stock quantity and a delayed safety stock quantity using the number of days required to reach the target value calculated in the second calculation step;
Generating the proper inventory quantity by calculating the appropriate inventory quantity by adding the delayed interval inventory quantity and the delayed safety inventory quantity to the production interval inventory quantity and the safety inventory quantity, and generating the appropriate inventory quantity information indicating the appropriate inventory quantity, and ,
An output step of outputting the appropriate inventory amount information;
A program that executes

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