JP2000348016A - Stock replenishing method by saffe stock rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for leveling total replenishment quantity and removing a replenishment requests exceeding supply capability as a stock replenishment system in a stock management business. SOLUTION: The ratio of safe stock quantity to demand quantity during a replenishing period is defined as a safe stock rate on hand. A safe stock rate calculation part 13 calculates the safe stock rate on hand on a plurality of items. A replenishment item decision part 14 arranges the items in the order of the smallest safe stock rate on hand and decides that the stock of the items whose total replenishment request quantity is within the range of a replenishment capability is replenished starting from the head item. A replenishment item output part 15 informs a supply part of the replenishment request quantity of the replenishment item in accordance with the replenishment decision of stock.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inventory management operation performed by using a computer, and more particularly to a method for determining an item to be restocked based on a safety stock ratio of an inventory item.

[0002]

2. Description of the Related Art Typical stock replenishment methods include a fixed quantity ordering method and a regular ordering method. The fixed-quantity ordering method is a method of requesting replenishment when inventory is paid out due to demand and the amount of inventory falls below the theoretically required amount of inventory. The regular ordering method is a method in which a replenishment interval is constant and a required amount of replenishment is requested based on demand forecast on a replenishment target date.

As a technique for determining the priority of inventory replenishment for a plurality of items, for example, Japanese Patent Application Laid-Open No. 7-98741
There is a technology disclosed in Japanese Unexamined Patent Publication (Kokai) No. H10-26095. According to this technology, the available inventory is divided by the demand speed to calculate the number of days on hand, the supply lead time is subtracted from the number of days on hand to determine the number of spare days, and the items are sorted in ascending order of the number of spare days, Request replenishment in order from the item with the smallest number.

[0004]

According to the conventional fixed-quantity ordering system, when replenishing a large number of products, the replenishment timing varies depending on the items, the total replenishment amount fluctuates, and the production plan on the supply side is reduced. There is a problem that it is difficult to stand.
In addition, according to the regular ordering method, when replenishing a large number of products, the replenishment timing becomes uniform for all items,
There is a problem that the total replenishment request temporarily exceeds the supply capacity.

Further, as a conventional stock replenishment method, a fixed quantity ordering method and a regular ordering method are separately provided, and it is difficult to use both methods depending on the item. For this reason, it is difficult to change the inventory replenishment method when the inventory management characteristics of the item change.

An object of the present invention is to level the total replenishment amount, eliminate replenishment requests exceeding supply capacity, and reduce the effective stock amount.

[0007]

According to the present invention, when the ratio of the safety stock to the demand in the replenishment period is defined as the on-hand safety stock ratio, the on-hand safety stock ratio is calculated for each of a plurality of items. The stock replenishment method is characterized by arranging the items in ascending order of the on-hand safety stock ratio, and deciding to restock the items whose total replenishment request amount falls within the range of the supply capacity frame in order from the first item.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a computer that performs inventory replenishment processing according to this embodiment. This computer is arranged between the production department and the distribution department, and is a computer that manages inventory of warehouses and the like. A plurality of computers / terminals 7 are connected to the processing device 1 of the computer via a storage device 2, a display device 3, an input device 4, a printer 5, and a network 6. The storage device 2 stores the respective tables from the stock table 31 to the replenishment information transmission table 38 constituting the database. The display device 3 is a device that displays a guidance screen or the like for data input. The input device 4 is a device for inputting data to be set in a table and inputting parameters for executing a program. The printer 5 is a device that outputs the created supplementary information transmission table and the like. The computer / terminal 7 is a server computer or terminal device installed in a warehouse, a production department, or the like, such as a terminal device for inputting data set in a table, a computer for receiving a supplementary information transmission table, and the like.

The memory of the processing unit 1 has a data input unit 1
1. Each program of a stock receipt / payout calculation unit 12, a safety stock ratio calculation unit 13, a replenishment item determination unit 14, a replenishment item output unit 15, and a database access unit 16 is stored and executed by the processing device 1.

FIG. 2 is a diagram showing the structure of the database stored in the storage device 2, showing the contents of each table from the stock table 31 to the replenishment information transmission table 38 and the links provided between the tables. is there. Inventory table 3
Reference numeral 1 denotes stock information for the day of processing, which has a table for each item code. The on-hand inventory amount A is the actual inventory amount of the actual product. The remaining order B is the quantity of stock items that have been requested to be replenished to the supplier but have not been actually delivered. On-hand inventory A and remaining order B
Is called the effective stock amount AB. The theoretical safety stock ratio Rh and the on-hand safety stock ratio Rs are the results of the safety stock ratio calculation. The safety stock ratio refers to the ratio of the safety stock amount occupying in the replenishment period. The case where the safety stock amount is based on the theoretical value is called the theoretical value safety stock ratio Rh, and the case where the safety stock amount is based on the on-hand stock amount is the on-hand safety stock ratio Rs. Call.

The delivery table 32 is delivery information and has a table for each item code and each demand day. Demand volume Ou
t is the amount paid out from the on-hand inventory amount in the inventory table 31. A situation where the on-hand inventory is less than the demand and cannot be paid out is called out of stock or out of stock. Receiving table 3
Reference numeral 3 denotes storage information, which has a table for each item code and each supply date. The supply amount In is a storage amount to be added to the on-hand inventory amount in the inventory table 31. The demand condition table 34 is provided for each item code, and sets an average demand Qd, a standard deviation σ of the average demand, and a safety coefficient k. The average demand is the demand per unit period. The safety coefficient k is a safety stock coefficient for setting a service rate, and a general value is 1.0.
Use ~ 6.0. If the service rate is 95%, k =
1.96.

The supply condition table 35 is provided for each item code and each supply source, and sets a replenishment lot size Qs, a supply lead time Ls, an interval flag, a fixed point flag, and a replenishment interval T. The replenishment lot size Qs is an economic lot size in the case of quantitative replenishment, and is 1 or more.
The supply lead time Ls is the number of days required for supply from the request for replenishment of the item to the receipt of the item as the supply amount In in the receipt table 33, and is a value of 1 or more. The interval flag is turned on when replenishing the item in the regular order method. The fixed point flag is turned on when replenishing the item, particularly in the quantitative ordering method. Refill interval T
Is effective when the interval flag is ON, and is the number of days between replenishment intervals. Both the interval flag and the fixed point flag are set to off or one of them is set to on. The regular order method does not sell well and is suitable for items with a long supply lead time. The fixed order method is suitable for items that sell well and have a short supply lead time. The supply source table 36 stores a supply capacity frame Es and a total replenishment request amount Qt for each supply source code. E
Both s and Qt indicate the supply capacity amount and the total amount of replenishment requests independent of the item.

The replenishment item determination table 37 includes items for each item,
It is a table provided for each supplier and determining whether or not to replenish the item from the supplier. The theoretical value safety stock rate Rh and the on-hand safety stock rate Rs are data acquired from the stock table 31 of the corresponding item. The supply lead time Ls, the interval flag, and the fixed point flag are data acquired from the supply condition table 35 of the corresponding item and the supply source. The required replenishment amount Qr is a required replenishment amount of the item calculated based on the interval flag, the fixed point flag, and the replenishment interval T of the corresponding supply condition table 35. The arrangement order P is the order of the replenishment item determination table 37 within the same supply source when the replenishment item determination table 37 is classified in ascending order of the on-hand safety stock ratio Rs for each supply source. The replenishment determination flag is a flag indicating whether the item is to be refilled (ON) or not (OFF).

The replenishment information transmission table 38 is a table for transmitting the items determined to be replenished to the supply source, and sets a supply source code, an item code, a supply date, a replenishment request amount Qr, and an arrangement order P. The requested replenishment amount Qr and the arrangement order P are values set in the corresponding replenishment item determination table 37.

FIG. 3 is a diagram showing a schematic procedure of the stock replenishment process of the present embodiment. The database access unit 16
From the storage device 2, an inventory table 31, an outgoing table 32,
The storage table 33, the demand condition table 34, the supply condition table 35, and the supply source table 36 are read (step 41). Next, the data input unit 11 stores the data input from the input device 4 or the computer / terminal 7 in the inventory table 31, the demand condition table 34, the supply condition table 35, and the supply source table 36 (Step 42). Next, the data input unit 11 stores input data relating to stock receipt / payment in the outgoing table 32 and the incoming table 33 (step 43). Next, the inventory receipt / payment calculation unit 12 calculates the inventory table 31, the outgoing table 32, and the incoming table 33.
Is calculated using the data of (1), and the result is stored in the inventory table 31 (step 44). Next, the safety stock ratio calculation unit 13 calculates the safety stock ratio using the stock table 31 and the demand condition table 34, and stores the result in the stock table 31 (step 45). Next, the replenishment item determination unit 14 creates a replenishment item determination table 37 from the stock table 31 and the supply condition table 35, determines an item to be replenished using the supply source table 36, and determines a result of the replenishment item determination. It is stored in the table 37 (step 46). Next, the replenishment item output unit 15 creates a replenishment information transmission table 38 from the replenishment item determination table 37 to be replenished, and transmits it to the computer / terminal 7 of each supply source via the network 6 (step 47). Finally, the database access unit 16 stores the created tables from the stock table 31 to the supplementary information transmission table 38 in the storage device 2 (step 48).

FIG. 4 is a PAD diagram showing a detailed processing flow of step 42. The data input unit 11 stores the item code of each inventory item input from the computer / terminal 7 via the input device 4 or the network 6 in the inventory table 31 (step 51). Next, the input demand condition of each item is stored in the demand condition table 34 (step 5).
2). Next, the input supply condition of each item is stored in the supply condition table 35 (step 53). Next, the input data relating to the supply source is stored in the supply source table 36 (step 54).

FIG. 5 is a PAD diagram showing a detailed processing flow of step 43. The data input unit 11 stores the receipt data of each item input from the computer / terminal 7 via the input device 4 or the network 6 in the receipt table 33 (Step 61). Next, the input retrieval data of each item is stored in the retrieval table 32 (step 62).

FIG. 6 is a PAD diagram showing a detailed processing flow of step 44. The stock receipt / payment calculation unit 12 repeats the following processing for the data of each item code in the receipt table 33 corresponding to the supply date (step 71). First, the supply amount In is stored in the inventory table 31 for the same item code.
(Step 72). Next, the same supply amount In of the receiving table 33 is subtracted from the remaining order B of the stock table 31 of the same item code (step 7).
3). When the processing for the supply amount in the storage table 33 is completed, the following processing is repeated for the data of each item code in the storage table 32 corresponding to the demand date (step 74). First, stock table 3 for the same item code
It is determined whether or not the on-hand inventory amount A is smaller than the demand amount Out of the delivery table 32 (step 75). If the stock on hand is smaller than the demand, the out-of-stock is transmitted to the demanding computer / terminal 7 via the network 6 and the outgoing process for the item is skipped (step 76). If the on-hand inventory is equal to or more than the demand, the demand Out of the delivery table 32 is subtracted from the on-hand inventory A of the stock table 31 (step 77).

FIG. 7 is a PAD diagram showing a detailed processing flow of step 45. The safety stock ratio calculator 13 repeats the following processing for the data of each item code in the stock table 31 (step 81). First, the average demand Qd, the average demand standard deviation σ, and the safety coefficient k in the demand condition table 34 having the same item code in the inventory data 31 are read (step 82). Next, the supply lead time Ls of the supply condition table 35 having the same item code is read (step 83). Next, the theoretical value safety stock ratio Rh is calculated according to the formula 1 and stored in the stock table 31 (step 8).
4). Rh = (k · sqrt (Ls) · σ) / (Qd · Ls) (Equation 1) Next, the on-hand safety stock ratio Rs is calculated according to Equation 2 and stored in the stock table 31 (step 85). Rs = ((A + B) −Qd · Ls) / (Qd · Ls) (Equation 2) Here, A + B is the effective stock amount AB, and Qd · Ls is the demand amount for the replenishment period, so (A + B) − Qd
Ls is the safety stock amount, and Rs is the ratio of the safety stock amount to the demand amount required during the replenishment period. It can be said that the smaller the value of Rs, the easier the stock-out occurs.

FIGS. 8A and 8B are PAD diagrams showing the detailed processing flow of step 46. FIG. The replenishment item determination unit 14 repeats the following processing for the data of each item code in the inventory table 31 (step 91). That is, the supply condition table 35 corresponding to the stock table 31 of each item code is referred to, and the replenishment item determination table 37 is generated from both tables (step 92). As the supply source code of the replenishment item determination table 37, the supply source code of the supply condition table 35 is transcribed. The values in the stock table 31 are transcribed for the theoretical value safety stock rate Rh and the on-hand safety stock rate Rs.
As the required replenishment amount Qr, the replenishment lot size Qs in the supply condition table 35 is transcribed, and Qr = Qs. The values of the supply condition table 35 are transcribed for the supply lead time Ls, the interval flag, and the fixed point flag.

Next, the entire replenishment item determination table 37 is classified by supply source code, and the on-hand safety stock ratio Rs for the replenishment item determination table 37 having the same supply source code.
(Step 93). Next, the following processing is repeated for each supply source code in the replenishment item determination table 37 (step 94). First, the arrangement order numbers 1, 2,.
Is set to the order P of the table (step 9)
5). Next, the replenishment determination flags are turned on for all the items of the same supply source code (step 96). Next, the total replenishment request amount Q of the supply source table 36 corresponding to the supply source code
t is cleared to zero (step 97).

8B, the following processing is repeated for each supply source code and each item code in the replenishment item determination table 37 (step 98). First, if the interval flag is turned on in the replenishment item determination table 37 (step 99 YES), the supply date table is referred to the replenishment interval T with reference to the supply condition table 35 corresponding to the item code and the supply source code. It is determined whether this is the case (step 100). The processing date is represented by the serial date of the year. If the remainder of the serial date / T is 0, the replenishment date is not used. If the date corresponds to the target date for replenishment, the required replenishment amount Qr is calculated according to Equation 3 and set as the required replenishment amount Qr (step 101). Qr = (Qd · (Ls + T) + k · sqrt (Ls + T) · σ) −A (Equation 3) Here, Qd, k and σ refer to the demand condition table 34 corresponding to the item code. T is the number of days between refills. The on-hand stock amount A refers to the stock table 31 corresponding to the item code. Further, Qr indicates the difference between the required stock amount of the theoretical regular ordering system and the stock amount on hand A. If the processing day does not correspond to the target date for replenishment (step 100 NO), the replenishment determination flag is turned off (step 102).

If the fixed point flag is ON in the replenishment item determination table 37 (step 103 YES), it is determined whether or not the on-hand safety stock rate Rs is smaller than the theoretical value safety stock rate Rh (step 104). Rs corresponds to the current stock amount, and Rh corresponds to the required stock amount. If Rs <Rh, the replenishment request amount Qr is the already set Qs.
If Rs ≧ Rh, the replenishment determination flag is turned off (step 105).

Next, if the replenishment decision flag is on in the replenishment item decision table 37 (step 106YE).
S), the supplier table 36 corresponding to the supplier code
The replenishment request amount Qr is added to the replenishment request total amount Qt, and Qr is accumulated (step 107). Next, it is determined whether or not the total replenishment request amount Qt in the supply source table 36 exceeds the supply capacity frame Es (step 108). If Qt> Es, the replenishment decision flag in the replenishment item decision table 37 is turned off (step 109).

According to the processing of the replenishment item determination unit 14 described above, the replenishment item determination table 37 for the same supply source
Are arranged in ascending order of the on-hand safety stock ratio Rs, and the replenishment item determination table 37 of the upper item code in the range in which the replenishment request total amount Qt, which is the total value of the replenishment request amount Qr, does not exceed the supply capacity frame Es. It is determined, and the replenishment item determination table 37 of the remaining item code is rejected for replenishment. At this time, if the interval flag is set to ON, the replenishment request amount Qr is calculated according to the periodic order method if the replenishment date is on the replenishment date, and if the replenishment date is not on the replenishment request date, it is excluded. For items for which the fixed-point flag is set to ON, the required replenishment amount Qr is determined in accordance with the fixed-quantity ordering method, and is excluded from replenishment when the possibility of running out of stock is low (Rs ≧ Rh).

The replenishment request total amount Qt does not depend on the item, but the change for each item is standardized by the replenishment lot size Qs of each item except for the case where the regular order method is taken into account. Further, the processing of the replenishment item determination unit 14 assumes that inventory of one item is replenished from one supply source. If the stock of one type of item can be replenished from a plurality of suppliers, the replenishment item determination table 37 having an overlapping item code is set in step 95 before setting the arrangement order P of the replenishment item determination table 37. It is advisable to leave one but exclude the others.

FIG. 9 is a PAD diagram showing a detailed processing flow of step 47. The replenishment item output unit 15 repeats the following processing for each supply source code and for each item code in the replenishment item determination table 37 (step 121). If the replenishment determination flag of the replenishment item determination table 37 is ON (YES in step 122), the replenishment information transmission table 3
8 is transferred to the replenishment information transmission table 38 that has generated the supply source code, the item code, the replenishment request amount Qr, and the arrangement order P of the replenishment item determination table 37 (step 123). Next, the supply date of the supplementary information transmission table 38 is calculated according to the formula 4, and stored in the supplementary information transmission table 38 (step 124). Supply date = processing day date + Ls (Equation 4) Next, the replenishment request amount Qr of the replenishment information transmission table 38 is added to the remaining order B of the stock table 31 of the item (step 125).

When the above processing is completed for all the replenishment item determination tables 37, the replenishment information transmission table 38
Is output on the printer 5 (step 126).
Further, the supplementary information transmission table 38 is transmitted to each computer / terminal 7 for each supply source (step 127). The arrangement order P of the supplementary information transmission table 38 is information indicating the priority of supplementation.

The supply capacity frame Es, the demand data and the period were set, and the time series changes of the total replenishment amount and the effective stock amount AB were obtained by the simulation of the method of the present invention. In addition, a simulation was also performed for the conventional quantitative ordering method and the regular ordering method for the same demand data and period without any limitation on the supply capacity frame, and compared with the simulation results of the method of the present invention. As a result, the system of the present invention has obtained a simulation result that the total replenishment amount is leveled and the effective stock amount AB is further reduced as compared with the conventional fixed-quantity ordering system and the regular ordering system. It is considered that the method of the present invention in which items to be replenished are selected in ascending order of the safety stock ratio on hand contributes to the reduction of the effective stock amount.

[0031]

As described above, according to the present invention, in replenishing a large number of items, the items are arranged in ascending order of the safety stock ratio on hand, and the total replenishment request amount is calculated in order from the top item. Is selected to replenish the stock, so that the total replenishment amount can be leveled, replenishment requests exceeding the supply capacity can be eliminated, and the effective stock amount can be reduced. Further, it is easy to take into account the conditions of the fixed-quantity ordering method or the regular ordering method according to the change in the inventory management characteristics of the item.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a computer that performs inventory replenishment processing according to an embodiment.

FIG. 2 is a diagram illustrating a configuration of a database according to the embodiment.

FIG. 3 is a diagram showing a schematic procedure of a stock replenishment process of the embodiment.

FIG. 4 is a PAD diagram showing a flow of processing of a data input unit 11 of the embodiment.

FIG. 5 is a PAD diagram showing a flow of a stock receipt / payment data input process of the embodiment.

FIG. 6 is a PAD diagram showing a flow of processing of a stock receipt / payout calculation unit 12 of the embodiment.

FIG. 7 is a PAD diagram showing a flow of processing of a safety stock ratio calculation unit 13 of the embodiment.

FIG. 8A is a PAD illustrating a flow of a process performed by a replenishment item determining unit 14 according to the embodiment.

FIG. 8B is a PAD (continued) illustrating a processing flow of the replenishment item determining unit 14 according to the embodiment.

FIG. 9 is a PAD diagram showing a flow of processing of a supplementary item output unit 15 of the embodiment.

[Explanation of symbols]

13: safety stock ratio calculation unit, 14: replenishment item determination unit, 1
5: replenishment item output unit, 31: stock table, 32: outgoing table, 33: incoming table, 34: demand condition table, 35: supply condition table, 36: supply source table,
37: supplementary item determination table, 38: supplementary information transmission table

Claims (3)

[Claims] In a method of calculating a stock replenishment amount using a computer, when a ratio of a safety stock amount to a demand amount in a replenishment period is a hand-held safety stock ratio, each of a plurality of items is held. Calculates the safety stock rate, arranges the items in ascending order of the safety stock rate, and determines to replenish the stock of the items whose total replenishment request amount falls within the supply capacity frame in order from the top item. Inventory replenishment method by safety stock ratio. 2. The method according to claim 1, wherein items whose safety stock ratio on hand is larger than a theoretical safety stock ratio are excluded from items to be stocked. 3. The stock replenishment method according to claim 1, wherein items having a predetermined replenishment interval are excluded from the items to be restocked, which do not correspond to the replenishment target date.