JP6509063B2 - Order number determination method, order number determination device and order number determination program - Google Patents

Description

  The present invention relates to a technology for leveling the order quantity of a product or parts constituting the product.

  As a method of inventory management, there are a fixed order point method and a regular order point method. In the fixed order point method, when the number of items in stock is reached, a fixed amount of orders is placed. In the regular order point method, it is possible to place an expected amount of orders at regular intervals.

  In Patent Document 1, items are divided into those with high demand and those with low demand, and for items with high demand, the required number calculated by MRP (Materials Requirements Planning) is the number of orders, and the demand is low It is described that the order is placed by the fixed order point system.

  Patent Document 2 describes that a lower limit and an upper limit are provided for the ordered amount, and the ordered amount is corrected when the ordered amount falls below the lower limit and when it exceeds the upper limit.

JP, 2005-29368, A Japanese Patent Application Laid-Open No. 08-96033

In the techniques described in Patent Documents 1 and 2, it is not considered to stabilize the load of the manufacturer, and the order amount fluctuates. Therefore, the load on the manufacturer may fluctuate, and as a result, the on-time delivery rate may decrease. In addition, the work of the manufacturer may be wasted and cost may be increased.
The object of the present invention is to equalize the ordered quantity while stabilizing the procurement and suppressing the excess inventory.

The method for determining the number of orders according to the present invention is
A leveling number calculation step of calculating the number of leveling orders by dividing the number of uses of the target item in the reference period by the number of times of procurement of the target item in the reference period;
An inventory storage step of storing a lower limit inventory number which is a lower limit value of the inventory of the target product and an upper limit inventory number which is an upper limit value;
If the expected stock quantity of the target product after the procurement period from the ordering of the target product to the delivery is equal to or higher than the lower limit stock and not higher than the upper limit stock stored in the stock storage step, the leveled number And an order number determination step of determining the leveling order number calculated in the calculation step as the number of orders of the target product.

  In the present invention, the upper limit and the lower limit are set in the stock, and when the expected stock count after the supply period is between the lower limit and the upper limit, it is assumed that the order count is constant. Therefore, the order quantity is equalized and the load on the manufacturer is stabilized. In addition, if the lower limit and the upper limit are appropriately set, it is possible to prevent shortage of stock and excess stock.

FIG. 1 is a block diagram of an order quantity determination system 1 according to a first embodiment. 6 is a flowchart showing leveling processing according to the first embodiment. Explanatory drawing of a lower limit inventory number and an upper limit inventory number. 6 is a flowchart showing an ordering process according to the first embodiment. Explanatory drawing of the number of orders of object goods. FIG. 2 is a diagram showing an example of a hardware configuration of an order quantity determination device 20 shown in the first embodiment.

Embodiment 1
FIG. 1 is a block diagram of the order quantity determination system 1 according to the first embodiment.
The order number determination system 1 includes a base system 10 and an order number determination device 20. The infrastructure system 10 and the order quantity determination device 20 are connected via a network.
The base system 10 is a system that manages manufacture, sales, and the like of products. The order number determination device 20 is a device that determines an order quantity for ordering an article such as a product and parts constituting the product from the manufacturer.

The base system 10 includes a usage record storage unit 11, a production plan storage unit 12, a sales plan storage unit 13, a BOM storage unit 14, a procurement cycle storage unit 15, and an MRP 16 (Materials Requirements Planning).
The usage record storage unit 11 is a storage device that stores the past usage records of articles. The production plan storage unit 12 is a storage device storing a production plan. The sales plan storage unit 13 is a storage device storing a sales plan. The BOM storage unit 14 is a storage device that stores information of an article such as a product and parts constituting the product. The procurement cycle storage unit 15 is a storage device that stores a procurement cycle for each item. The MRP 16 calculates the required amount of parts and the like from the production plan, and calculates the expected stock amount and the like from the production plan and the sales plan.

The order number determination device 20 includes a target item selection unit 21, an extraction pattern determination unit 22, a leveling number calculation unit 23, an inventory determination unit 24, an order number determination unit 25, and a storage device 26. The storage device 26 includes a target item storage unit 261, a target period storage unit 262, and an inventory storage unit 263.
About each part with which the number determination device 20 of orders is provided, it demonstrates with the process of the number determination device 20 of numbers. The processing of the order quantity determination device 20 is divided into leveling processing and order processing. Each process of the order quantity determination device 20 corresponds to each process of the order quantity determination method.

FIG. 2 is a flowchart showing the leveling process according to the first embodiment.
The leveling process is performed, for example, every long period such as every year, every period, every month. Also, it is executed at an arbitrary timing based on the user's instruction.

(S11: Target product selection process)
The target item selection unit 21 selects a target item for which the number of orders is to be equalized among a plurality of items. The target product selection unit 21 stores the identification information of the selected target product in the target product storage unit 261.

  The target item selection unit 21 selects an item having a large demand amount and having a small fluctuation in the number of uses from year to year, as a target item, based on the use results of each item stored by the use result storage unit 11. For example, the target item selection unit 21 selects an article for which the average number of uses for one year is equal to or greater than a predetermined first threshold and the variation in the number of uses for each year is equal to or less than a predetermined second threshold. Select as target product.

  The condition of the target product that the demand amount is high is because the leveling of the ordered amount of the high demand amount articles rather than the low demand amount articles has a large effect on the stability of the load of the manufacturer. is there. The condition that the variation in usage results is small is considered as the condition of the target product because, if the variation is large, it is necessary to have a large inventory to level the order quantity, which is inappropriate.

(S12: Extraction pattern determination processing)
The extraction pattern determination unit 22 determines, for each target item, an extraction pattern of data in which the variation in the number of usages for each year decreases. The extraction pattern determination unit 22 stores the determined extraction pattern in the target period storage unit 262.

For example, the extraction pattern determination unit 22 extracts the use number of 12 months from January to December, extracts the use number of 12 months from April to March of the next year, and The case where the number of use for 12 months until August of the following year is extracted, etc. are set as the extraction pattern of data. Then, the extraction pattern determination unit 22 selects, from the set extraction patterns, an extraction pattern that minimizes the variation in the number of times of use for each year.
The extraction pattern determination unit 22 calculates the variation index for the set extraction pattern according to Equation 1, and selects the extraction pattern having the smallest variation index, thereby minimizing the variation of the number of usages per year. It can be selected.
(Formula 1)
Fluctuation index = (((σ _n1 ) ² + (σ _{n 2} ) ² + (σ _{n 3} ) ² +... + (Σ _nm ) ² ) / m
Here, σ _nm is a standard deviation of the number of usages of the year n to the year m. That is, the value obtained by averaging the standard deviations for a plurality of years is the fluctuation index. Based on the additivity of the variance, Equation 1 holds.

(S13: Leveling number calculation process)
The leveling number calculation unit 23 calculates the number of leveling orders for each target product. The leveling number calculation unit 23 stores the calculated number of leveling orders in the procurement cycle storage unit 15.

The leveling number calculation unit 23 extracts, from the usage record storage unit 11, data of the number of uses of the target product for the past m years according to the extraction pattern of the target product determined in S12. The leveling number calculation unit 23 calculates the average of the number of uses in one year from the extracted data. Then, the leveling number calculation unit 23 divides the calculated average by the number of procurements in one year to calculate the number of leveling orders.
That is, the number of leveled orders is expressed by Equation 2.
(Formula 2)
Here, the number of procurements per year can be specified by referring to the procurement cycle storage unit 15 by referring to the procurement cycle storage unit 15.

(S14: Inventory determination processing, inventory storage processing)
The stock determination unit 24 calculates the lower limit inventory number and the upper limit inventory number for each target item. The inventory determination unit 24 stores the calculated lower limit inventory number and upper limit inventory number in the inventory storage unit 263.

For example, the inventory determination unit 24 calculates the lower limit inventory number and the upper limit inventory number by Equation 3.
(Equation 3)
Standard stock number = Leveling order number / 2 + safety factor × ((procurement period) × standard deviation Lower limit stock number = Leveling order number / 2 + lower limit safety factor × ((purchase period) × standard deviation Upper limit stock number = Leveling order Number / 2 + upper limit safety factor × ((procurement period) × standard deviation Here, "safety factor × √ (procurement period) × standard deviation" is generally called a safety stock. The lead time is the period from the time an object is ordered to the time it is delivered, and is expressed as a multiple of the unit period. For example, in the case where it takes 15 days to order and deliver the target product, if the unit period is one day, the lead time is represented as 15, and if the unit period is one month, the lead time is 0.5 It is expressed as The standard deviation is the standard deviation of the number of objects used in the unit period. Moreover, a safety factor is a value converted by a normal distribution table from a safety factor which is a probability that a shortage will not occur.

FIG. 3 is an explanatory view of the lower limit inventory number and the upper limit inventory number.
In FIG. 3, the vertical axis represents the number of stocks, and the horizontal axis represents time. Further, in FIG. 3, a thick line 33 indicates the number of stocks at each time.
The standard stock quantity is the sum of the number of leveled orders / 2 and the safety stock. Therefore, when the broken line 31 is drawn at a position where the number indicated by the symbol A and the number indicated by the symbol B are equal, the arrow 32 indicates the reference inventory number.
"Low limit safety factor × ((procurement period) × standard deviation" is referred to as the lower limit safety stock, and "upper limit safety factor × 調 達 (procure period) × standard deviation" is referred to as the upper limit safety stock. The lower limit safety factor is a value smaller than the safety factor, and the upper limit safety factor is a value larger than the safety factor. Therefore, the lower limit safety stock is less than the safety stock, and the upper limit safety stock is more than the safety stock. The lower limit inventory number is smaller than the reference inventory number, and the upper limit inventory number is larger than the reference inventory number.
Furthermore, here, when calculating the standard inventory quantity, the lower limit inventory quantity, and the upper limit inventory quantity, the number of leveling orders / 2, that is, 50% of the leveling orders, is used as the reference ratio of the leveling orders. . However, instead of the number of leveled orders / 2, another percentage of the number of leveled orders may be used as a reference percentage of the number of leveled orders. For example, when the triangle 35 (the hatched portion) formed by the thick line 33 representing the number of stocks and the line 34 representing the safety stock in FIG. 3 is divided into two by parallel lines of the horizontal axis, It is also possible to use the ratio indicated by the parallel line whose area is 1⁄2.

FIG. 4 is a flowchart showing the ordering process according to the first embodiment.
The ordering process is performed, for example, monthly, weekly, daily, etc., every short period. Also, it is executed at an arbitrary timing based on the user's instruction.
The ordering process is performed on each item in order.

(S21: Target determination process)
The order number determination unit 25 refers to the target item storage unit 261 to determine whether the item to be processed is a target item for which the number of orders is equalized or a stock replenishment item that is not the target item.
If it is a target product (target product in S21), the process proceeds to S22. On the other hand, if it is a stock replenishment product (stock replenishment product in S21), the process proceeds to S25.

(S22: stock determination process)
The order quantity determination unit 25 determines whether the expected stock quantity of the target product to be processed after the procurement period is equal to or more than the lower limit stock number of the target product and equal to or less than the upper limit stock number. The expected stock quantity of the target item after the lead time is calculated by MRP16.
If the expected stock quantity is equal to or more than the lower limit stock quantity and equal to or less than the upper limit stock quantity (YES in S22), the process proceeds to S23. On the other hand, if the expected inventory quantity is not less than the lower limit inventory quantity and not more than the upper limit inventory quantity (NO in S22), the process proceeds to S24.

(S23: Order number determination process (1))
The order number determination unit 25 determines the leveled order number of the target product to be processed as the number of orders.

(S24: Order number determination process (2))
The order number determination unit 25 corrects the leveling order number of the target product to be processed and determines it as the order number.
If the expected inventory quantity is less than the lower limit inventory quantity, the order quantity determination unit 25 adds the number obtained by subtracting the expected inventory quantity from the lower limit inventory quantity to the leveled order quantity to calculate the lower limit order quantity, and the lower limit Determine the number of orders as the number of orders for the target product. Further, when the expected stock quantity is larger than the upper limit stock quantity, the order quantity determination unit 25 calculates the upper limit order quantity by subtracting the number obtained by subtracting the upper limit stock quantity from the expected stock quantity from the leveled order quantity. Determine the maximum number of orders as the number of orders for the target item.

(S25: Order number determination process (3))
The number-of-orders determination unit 25 sets the required amount of the article to be processed in the period until the next order as the number of orders. The required amount is calculated by the MRP 16.

FIG. 5 is an explanatory diagram of the number of orders of target products.
If the expected inventory quantity is equal to or higher than the lower limit inventory quantity and lower than the upper limit inventory quantity (in the case of the standard), the order quantity is equal to the equalized order quantity. That is, as long as the expected stock quantity falls within the lower limit stock quantity and the upper limit stock quantity, the order quantity is constant.
If the forecasted inventory quantity is less than the lower limit inventory quantity, the difference X between the estimated inventory quantity and the lower limit inventory quantity is larger than the leveled order quantity. In other words, order to increase production gradually. On the other hand, if the expected stock number is larger than the upper limit stock, the difference Y between the expected stock number and the upper limit stock number is smaller than the leveling order number. In other words, order to reduce production gradually.

As described above, in the order quantity determination apparatus 20 according to the first embodiment, when the expected stock quantity after the procurement period for the target item is between the lower limit and the upper limit, it is assumed that the order quantity is constant. Therefore, the order quantity is equalized and the load on the manufacturer is stabilized.
In addition, production is gradually increased or decreased as much as filling the difference between the lower limit or the upper limit when the expected stock quantity is less than the lower limit or greater than the upper limit. Therefore, the load on the manufacturer does not greatly change.

  For stock replenishment products other than target products, the number of orders fluctuates because the required quantity is directly used as the number of orders. However, since the number of orders for the target product is stable, even if the number of stock replenishment orders changes, the load on the manufacturer is stabilized to some extent. In particular, the load on the manufacturer is likely to be stable, since articles in high demand are targeted.

  In the above description, one year is used as a reference period. And we made the condition of the target product that the demand fluctuation by year is small. This is because, for example, when one month or a half is used as a reference period, the demand fluctuates in many cases due to the influence of seasons and the like, and in many cases, the product can not be the object of leveling. However, taking such effects into consideration, the reference period may be another period such as one month or a half.

FIG. 6 is a diagram showing an example of the hardware configuration of the order quantity determination device 20 shown in the first embodiment.
The order number determination device 20 is a computer. Each element of the order quantity determination device 20 can be realized by a program.
As a hardware configuration of the order quantity determination device 20, an arithmetic device 901, an external storage device 902, a main storage device 903, a communication device 904, and an input / output device 905 are connected to a bus.

The arithmetic device 901 is a CPU (Central Processing Unit) or the like that executes a program. The external storage device 902 is, for example, a ROM (Read Only).
Memory, a flash memory, a hard disk drive, etc. The external storage device 902 is an example of the storage device 26. The main storage device 903 is, for example, a random access memory (RAM). The communication device 904 is, for example, a communication board or the like. The input / output device 905 is, for example, a mouse, a keyboard, a display device, or the like.

The program is usually stored in the external storage device 902, loaded in the main storage device 903 and sequentially read in and executed by the computing device 901.
The program is a program that implements the functions described as the target item selection unit 21, the extraction pattern determination unit 22, the leveling number calculation unit 23, the stock determination unit 24, and the order number determination unit 25.
Furthermore, an operating system (OS) is also stored in the external storage device 902, at least a part of the OS is loaded into the main storage device 903 and the computing device 901 executes the above program while executing the OS.
In the description of the above embodiment, the target item selection unit 21, the extraction pattern determination unit 22, the leveling number calculation unit 23, the stock determination unit 24, and the order number determination unit 25 select, determine, calculate, etc. The information described above is stored as a file in the main storage device 903.

  The configuration of FIG. 6 merely shows an example of the hardware configuration of the number-of-orders determination device 20, and the hardware configuration of the number-of-orders determination device 20 is not limited to the configuration shown in FIG. It may be.

  DESCRIPTION OF SYMBOLS 10 base system, 11 use record memory | storage part, 12 production plan memory | storage part, 13 sales plan memory | storage part, 14 BOM memory | storage part, 15 procurement cycle memory | storage part, 16 MRP, 20 order number determination apparatus, 21 target item selection part, 22 extraction Pattern determination unit, 23 leveling number calculation unit, 24 stock determination unit, 25 order number determination unit, 26 storage devices, 261 target item storage unit, 262 target period storage unit, 263 inventory storage unit.

Claims (11)

A leveling number calculation step of calculating the number of leveling orders by dividing the number of usage of the target product in the reference period by the number of times of procurement of the target product in the reference period ;
The lower limit stock whose predicted stock quantity of the target item after the procurement period from the time the order quantity determination unit orders the target item to the delivery is the lower limit value of the stock of the target item stored in the storage device If the number of equalizing orders calculated in the leveling number calculating step is determined as the number of orders of the target item if the number is equal to or more than the upper limit and is not more than the upper limit inventory number which is the upper limit value. How to determine the number of orders. The number-of-orders determining step is a lower limit number of orders obtained by adding the number obtained by subtracting the expected number of stocks from the lower limit number of stocks to the number of leveled orders, when the estimated number of stocks is less than the lower limit number of stocks. The upper limit order determined by subtracting the upper limit inventory number from the expected inventory number, which is determined as the number of orders for the target item and the expected inventory number is greater than the upper limit inventory number. The method for determining the number of orders according to claim 1, wherein the number is determined as the number of orders for the target item. The order number determination method further includes
The stock determination unit adds a reference number, which is the number of reference proportions of the number of leveled orders, to the lower limit safety stock, which is the product of the standard deviation of usage per unit period and the square root of the lead time and the lower limit safety factor. The upper limit stock is calculated by adding the reference number to the upper limit safety stock which is the product of the standard deviation of the amount used per unit period, the square root of the lead time and the upper limit safety factor. Have an inventory determination process to calculate the number,
Wherein the storage device, the order number determining method according to claim 1 or 2 wherein the lower inventory quantity and the upper limit inventory determined in inventory determination process is characterized Rukoto stored. The order number determination method further includes
For the plurality of articles , the article selection unit uses, as the article , an article in which the number of uses in the reference period is the first threshold or more and the variation in the number of uses in each of the reference periods is the second threshold or less The method for determining the number of orders according to any one of claims 1 to 3, further comprising a target item selection step to be selected. 5. The order number determination method according to claim 4, wherein the order number determination step determines, as the number of orders, the required number required for the next order placement for an item other than the target item. A leveling number calculation unit that calculates the number of leveling orders by dividing the number of uses of the target item in the reference period by the number of times of procurement of the target item in the reference period;
An inventory storage unit that stores a lower limit inventory number, which is a lower limit value of the inventory of the target product, and an upper limit inventory number, which is an upper limit value;
If the expected stock quantity of the target article after the procurement period from the ordering of the target article to the delivery is equal to or greater than the lower limit inventory quantity and equal to or lower than the upper limit inventory quantity stored in the inventory storage unit, the leveling And an order number determination unit that determines the leveling order number calculated by the optimization number calculation unit as the order number of the target product. The number-of-orders determining unit, when the predicted inventory number is less than the lower limit inventory number, adds the number obtained by subtracting the predicted inventory number from the lower limit inventory number to the leveled order number, The upper limit order determined by subtracting the upper limit inventory number from the expected inventory number, which is determined as the number of orders for the target item and the expected inventory number is greater than the upper limit inventory number. 7. The order quantity determination device according to claim 6, wherein the number is determined as the order quantity of the target item. The order number determination device further includes:
The lower limit stock by adding the reference number which is the number of the reference ratio of the number of leveled orders to the lower limit safety stock which is the product of the standard deviation of usage per unit period and the square root of the lead time and the lower limit safety factor. Calculate the upper limit stock number by adding the standard number to the upper limit safety stock which is the product of the standard deviation of usage per unit period and the square root of the lead time and the upper limit safety factor while calculating the number Equipped with a decision unit,
The order number determination apparatus according to claim 6 or 7, wherein the inventory storage unit stores the lower limit inventory number and the upper limit inventory number determined by the inventory determination unit. The order number determination device further includes:
For a plurality of articles, a target item selection unit that selects an article having the number of uses in the reference period is equal to or greater than a first threshold and the variation in the number of uses in each of the reference periods is equal to or less than a second threshold The order number determination apparatus according to any one of claims 6 to 8, comprising: 10. The order number determination device according to claim 9, wherein the order number determination unit determines, as the number of orders, the required number of items required until the next order for an item other than the target item. Leveling number calculation processing for calculating the number of leveling orders by dividing the number of uses of the target item in the reference period by the number of times of procurement of the target item in the reference period ;
Before SL forecast inventory of the target product after procurement period until the delivery after ordering the target products, lower inventory or more and the upper limit value is a lower limit value of the inventory of stored the target product in a storage device If the number is equal to or less than the upper limit inventory number, the computer is caused to execute an order number determination process of determining the leveling order number calculated in the leveling number calculation process as the number of orders of the target product. Order number determination program.

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