JPH10138102A - Production instructed quantity leveling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the manufacturing line in the appropriate operating condition in which the load of the manufacturing line is leveled and each kind can be produced with excellent balance by calculating the period until generation of the lot production request is predicted next, and performing the production in advance of a lot of the kind whose predictable period is shortest. SOLUTION: The period in which generation of the lot production request is predicted next in each kind belonging to the selected kind group is calculated based on the present inventory of the by-kind inventory table 11 and the information on the by-kind order-reception trend table 12, and one lot of the kind whose predictable period is shortest, is instructed through integration and selection by an in-advance production operating means 20. The production instructed quantity by the kind in the stage where the production instructed quantity to the line production capacity is in the prescribed range, is recorded by a determined production instructed quantity recording means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for leveling a production instruction amount for an assembly processing line for high-mix low-volume production, suppressing load fluctuations and maintaining proper operation.

[0002]

2. Description of the Related Art In the case of an assembly processing line for small-lot production of many kinds, when one kind is taken out, the net production demand per unit time greatly fluctuates. It is extremely difficult to level the load on the line in time series. As one of the methods of leveling the load of such a production line, the load is temporarily piled up based on the required amount of each kind, and the load is moved from a place with a large load to a place with a small load. It has been known.

[0003] That is, a fixed planning period is divided into a plurality of time buckets, the load of each type is added to each time bucket according to the delivery date of a request, and the time bucket with a large load is changed to a time bucket with a small load. The production instruction timing is shifted, and the load on each time bucket is leveled. Japanese Unexamined Patent Publication No. Hei 6-195345 discloses a method of selecting a part of target orders, moving only the target orders, and performing load calculation and adjustment in order to efficiently perform such load accumulation and landslide. Has been proposed.

[0004]

However, the leveling of the load by the above-mentioned method of stacking and crushing loads has the following problems. The first point is that if the load fluctuation range is to be reduced, the plan formulation period (period in which the production plan is fixed) becomes longer. As a result, the stock of the product type or its parts to be produced accompanying this increases. That is, even when a production instruction is assigned to the last time bucket in the planning period, a large amount of inventory must be held so that inventory is not exhausted.

[0005] The second problem is that even if the load is leveled, it is not considered in the above-mentioned load stacking / sloping method whether or not the leveled load level matches the production capacity. The present invention has been made in view of such a conventional problem, and it is possible to equalize the load on a production line, produce various types in a well-balanced manner, and maintain the production line in an appropriate operation state. It is intended to provide a production instruction leveling device.

[0006]

According to the present invention, there is provided a production amount leveling device comprising: a type-specific inventory recording means; a type-specific order tendency recording means; a type group recording means; a type group production target recording means; It has a recording means and a calculating means. The type-specific inventory recording means records the production lot size of each type and the current stock amount. And
The type-specific order tendency recording means records a trend of a time-series transition of a recent inventory amount of each type or a trend of a recent time-series order amount.

[0007] The type group recording means registers and records, as the same type group, a type group having a similar component configuration or a required load on a production line. And
The production target recording means for each product group registers and records an appropriate number of products (appropriate capacity) per time bucket for each product group. The line capacity recording means registers and records an appropriate production capacity per time bucket of the production line.

[0008] Then, the calculating means increases or decreases the advance production plan with respect to the net production demand for each product type in the predetermined time bucket, and calculates the production instruction amount for the time bucket as described below. That is, the arithmetic means has first arithmetic means, advanced product group selecting means, and advanced production arithmetic means, and the first arithmetic means carries forward the previous advanced production amount from the current production request amount to the previous production amount. The used amount is subtracted, and this is corrected for each lot to calculate the primary production instruction amount for each product type. Then, the advanced product group selecting means integrates the primary production instruction amount for each product group, and selects the product group whose integrated value deviates most from the appropriate production capacity of the product group.

[0009] The advanced production calculation means determines the time period until the next lot production request is predicted to occur in each of the types belonging to the selected type group, by comparing the current inventory with the type-specific order tendency recording means. The calculation is performed based on the information, and the production lot is instructed ahead of schedule for the kind of the product whose prediction period is the shortest. The prediction period is determined, for example, by predicting a period in which inventory is depleted due to a decrease in inventory, and calculating a production instruction time from the period and the manufacturing lead time of the product type.

[0010] The arithmetic means further includes control means, and the control means repeatedly operates the above means until the production instruction amount with respect to the line production capacity falls within a predetermined range. The calculation means has a fixed production instruction amount recording means, and records the production instruction amount for each type when the production instruction amount for the line production capacity falls within a predetermined range. As described above, the calculation means sets the production instruction amount in each time bucket within a certain range with respect to the line production capacity, and at the same time, levelizes the load on the line so that it does not vary for each time bucket. be able to. As a result, the production line can stably maintain an appropriate load, and the line can be operated efficiently.

[0011] In addition, the kind group to be produced ahead of time is selected in order from the kind group in which the production instruction amount deviates most from the appropriate production capacity of the kind group, so that the target value of the production instruction amount for each kind group is determined. Variance is minimized, and each variety group can be produced in a well-balanced manner. Further, the types of products to be produced ahead of schedule are sequentially specified in order from the ones expected to produce the production requests in the shortest time. Therefore, the inventory due to the advance production is consumed within the shortest time, and the waste of inventory is reduced.

According to the second aspect of the present invention, there is provided a method for selecting an advanced variety group in which one lot of a variety having a shortest period until a production request is predicted to occur next among the types belonging to the variety group. It is preferable to adopt a method of selecting a kind group having the lowest ratio of the production instruction amount to the production target amount when the production is advanced. This is because the suppression of the deviation of the production instruction amount from the target production amount
It is preferable that the evaluation is made based on the result at the determined production instruction amount. On the other hand, since the lot size of the variety varies depending on the variety, it is appropriate to compare the degree of deviation from the target amount based on the production amount on the assumption that the production is performed ahead of schedule.

Further, each component (means) of the arithmetic means is provided.
Can be configured by an information processing device such as a general-purpose computer or a microprocessor, and an application program. Similarly, other components except for the arithmetic unit can be easily formed as an information table in the information processing device.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 This example is directed to a production instruction quantity for leveling production instruction quantities for production lines α, β,... For prospectively producing a plurality of types a1, a2, b1, b2,. This is a leveling device 1 (FIG. 1). The device 1 is, as shown in FIG.
Type-specific inventory table 11 for recording the lot size of each type a1, a2, b1, b2,.
, An order-by-type tendency table 12 for recording the trend of inventory transition or order of each type a1, a2, b1, b2,..., And a type group (a1, a2, a2), (b1, b2, b3)
.. Are registered as the same type group A, B,.
B,..., A production capacity table 14 for each product type for registering an appropriate number of products per different time bucket, and a capacity per line for registering an appropriate production capacity per time bucket for the production lines α, β,. Table 15 and varieties a1, a2, b1, b2
··· Operation means 20 for calculating a production instruction amount for the time bucket by increasing / decreasing a forward production plan for each required production amount.

As shown in FIG. 2, the calculating means 20 subtracts the carry-over amount Pf of the preceding advanced production from the current net production request amount (order amount S), and corrects this value Po in lot units. First calculating means (steps 601 and 602) for calculating the primary production instruction amount P1 for each product type;
The next production instruction amount P1 is integrated for each product type group, and the integrated value Ps is set to a product type group M (M = A, B...) That is the shortest with respect to the appropriate production target of the product type group. Group selection means (steps 603, 6
05) and the time period T until the next lot production request is predicted to occur for each of the selected product types belonging to the product type group M, based on the current inventory in the product type inventory table 11 and the Calculated based on information
Advance production calculation means (steps 606, 60) for instructing the production of one lot of the product k with the shortest prediction period.
7) and control means (step 6) for repeatedly operating the above means until the line production instruction amount PL (L = α, β,...) With respect to the line production capacity falls within a predetermined range.
04) and the production instruction amount PL for the above-mentioned line production capacity
Is a predetermined production instruction amount recording means (Table 22 in FIG. 1) for recording the production instruction amount for each product type when the value falls within a predetermined range.
To 24).

The following is a supplementary explanation for each. The production instruction leveling device 1 of this example is composed of stored program-type computer hardware and an application program. As shown in FIG. Based on the command input from the means (keyboard) 41, the production instruction amount is determined for each product type. The data such as the determined production instruction amount is displayed on the display device 4.
3 can be displayed.

The varieties a1, a2, b1, b2
.., The product groups A, B,... And the product groups (a1, a2), (b1, b2, b3),. Constituent group A. .., As shown in Table 1,
This is recorded in the type group table 13.

[0018]

[Table 1]

Each type a1, a2, b1, b2,.
The lot size and the current stock amount are recorded in the stock table 11 for each product type as shown in Table 2. In addition,
As shown in Table 2, the inventory amount is separately recorded for the inventory amount corresponding to the lot produced earlier and the regular inventory amount corresponding to the normal inventory not produced earlier. For example, in Table 2, in the case of the product b1, the remaining amount corresponding to the regular stock is zero because all of the remaining amount has been consumed, and 4 lots have been paid out of the lot 12 produced ahead of schedule, and 8 pieces have been left in the forward inventory. I have.

[0020]

[Table 2]

Further, as shown in Table 3, the production capacity (target) table 14 for each type group includes
B, C..., The planned number of production units for the current month and the number of operating days of the current month, and the target production unit per day obtained by dividing the planned number of production units of the month by the number of operating days of the current month. In this example, the time bucket for determining the production plan is 0.25
Days, the target production volume per time bucket Pso
Is a value obtained by dividing the target production number per day by 4. That is, the target production quantity Pso per time bucket
The type group A has 31.25 units, the type group B has 83.75 units, and the type group C has 20.0 units.

[0022]

[Table 3]

As shown in Table 4, the production capacity table 15 for each line α, β, γ..., The number of working days in this month, and the production plan quantity for this month are shown in Table 4. Is divided by the number of operating days of the current month, and the line production capacity per day is recorded. In this example, since the time bucket for determining the production plan is 0.25 days, the line production capacity PLo per time bucket is:
This is a value obtained by dividing the line production capacity per day by 4. For example, the line production capacity per time bucket is 115 units for the line α and 52 units for the line β.

[0024]

[Table 4]

As shown in Table 5, the order tendency table 12 for each product type includes n days from the last three days to (n-2).
.., And a moving average of the three-day values is shown as an index indicating a recent order tendency.

[0026]

[Table 5]

The production demand S for the nearest time bucket simply calculated based on the order received until the previous day is:
It can be known from the order receiving table 16 (FIG. 1) having the contents shown in Table 6.

[0028]

[Table 6]

Then, as shown in FIG. 2, first, in step 601, the calculating means 20 calculates the carry-over stock amount P corresponding to the lot produced earlier from the production request amount S.
f, the O-th order production order Po (a1), P
o (a2), Po (b1)... are calculated. This is because only the carried inventory amount Pf of the required production amount S can be used for this inventory without production. For example, as shown in Table 2, the type b1 has eight forward-moving stocks Pf, so the primary production instruction amount Po (b1) is
There are 72 units (the forward inventory Pf is zero and Po = S for the types a1, a2, and b2).

Then, in step 602, the fraction of the O-th order production amount Po is cut and the next process is performed, the production order amount is set to an integral multiple of the lot, and the first production order amount P1 is determined. . For example, since the lot size is 12 for the product type a1, the O-th production instruction amount Po = 2
4 (= 12 × 2) becomes the primary production instruction amount P1 as it is, and the lot size is 12 for the product b1,
The O-th order production instruction amount Po = 72 becomes the first-order production instruction amount P1 = 72 (= 12 × 6) as it is, and the lot size is 8 for the type b2. = 8 is the primary production instruction amount P1 = 8 (= 8
× 1). On the other hand, in the varieties a2 and b3, the Po is 4 units and 6 units, both of which are smaller than the 8 units and 12 units of the lot size. Therefore, the primary production instruction amount P1 is zero.

In the following step 603, the primary production instruction amount P1 of the type to which the type belongs is integrated, and the type group A,
B, C... Are calculated, and the production instruction amounts Ps of the product groups to which they belong are integrated to calculate the production instruction amounts PL for the production lines α, β, γ. For example, the production instruction amount Ps of the kind group A is the kind a1, a
2 and the primary production instruction amount P1 is added to 24 units,
The production instruction amount Ps of the type group B is 80 units by adding the primary production instruction amount P1 of the types b1 to b3. In the production line α, the production instruction amounts Ps of the product groups A and B are integrated or the primary production instruction amounts P1 of the target products a1, a2, b1 to b3 are integrated, and the total is 104 units.

Then, in step 604, the production lines α, β, γ... Based on the primary production instruction amount P1
Whether or not the integrated production instruction amount PL for each time is a value close to the line production capacity PLo per time bucket;
It is determined whether or not the value becomes closer to the target value when a lot is added. For example, the PL of the production line α is 10
Since the number is four, which is not a value close to the production capacity PLo, but becomes closer to the target value when one lot is added, the process proceeds to the next step 605.

In step 605, the production lines α,
Among the product groups A, B,... belonging to β, γ,..., the product group having the lowest fulfillment rate for the target production number Pso per time bucket of the product group with the product instruction amount Ps of the product group is selected. I do. For example, in the case of the production line α, the filling rate of the product group A (24/3
Since 1) is smaller than the filling rate (80/84) of the type group B, the type group A is selected here.

Next, in step 606, the types a1, a1 belonging to the type group A selected in step 605 are selected.
Among the items a2, a variety k that is predicted to be issued at the nearest time is selected. This selection depends on the current inventory status (data of the inventory table 11 by type shown in Table 2),
The determination is made based on the order status (data of the type-specific order tendency table 12 shown in Table 5).

This selection criterion is based on a change in inventory due to an order as shown in FIG. 3, and a period T (= t1) from the current time to until a time t1 when it is predicted that the inventory will decrease and a production instruction will be issued. −to) is a method of selecting the kind k having the smallest value. In the figure, the stock curve from the present time “to” is obtained by extending the recent trend of orders. (A) and (b) show an example of an inventory curve in a case where advance production is not performed, and FIG.
Shows an example of an inventory curve in a case where advanced production is performed at time t2.

The prediction period T in which a production instruction is issued is:
Since it is the same as the stock ratio σ for each product type defined by the following equation, the product type k having the lowest value σ is selected. Inventory ratio σ = (regular inventory + advanced inventory) ÷ (average order quantity) Table 7 shows data relating to this inventory ratio σ and, as shown in FIG. It is held in the calculating means 20. As can be seen from Table 7, the type a1 is selected from the type group A in this example because the stock ratio σ (predicted period T) of the type a1 is smaller than the type a2.

[0037]

[Table 7]

Next, in step 607, step 6
06, the primary production instruction amount P1 (a
1) is added for only one lot (8 units). As a result, the primary production instruction amount P1 (a1) of the product type a1 is corrected from 0 to 8 units. Next, returning to step 603, the new first
Product group A based on the next production instruction amount P1 (a1)
Production instruction amount Ps and integrated production instruction amount P of the production line α
Update L. As a result, the production instruction amount Ps of the product type group A is updated from 24 units to 32 units, and the integrated production instruction amount PL of the production line α is changed from 104 units to 112 units.

Then, in step 604, again
Total production instruction amount PL for each production line α, β, γ ...
Is the line production capacity PLo per time bucket
It is determined whether the value is closer to the target value and whether the value is closer to the target value when one lot is added. The updated production instruction amount PL (= 112 units) of the production line α is:
The line production capacity PLo per time bucket (=
115), the result of step 604 is inevitable, and in step 610, the determined production instruction amount is determined as the production-specific table 2 shown in FIG.
2. The contents shown in Tables 8 to 10 are recorded in the production table 23 for each product group and the production table 24 for each line.

[0040]

[Table 8]

[0041]

[Table 9]

[0042]

[Table 10]

As described above, according to the production instruction leveling device 1 of this embodiment, the load on the production line is maintained within a certain range with respect to the production capacity by appropriately executing the advance production instruction. As a result, the load of each time bucket can be leveled and an appropriate operation rate can be maintained, so that the line can be made more efficient. At the same time, a type group to be moved forward is selected so that the level of the production instruction amount with respect to the target production number for each type group has the smallest variation (step 605). Further, since the type of the product for which the advance production is instructed is sequentially specified from the one in which the production request is predicted to be issued closest (step 606), the inventory by the advance production is consumed in the shortest time, and the inventory is reduced. Less waste.

Embodiment 2 This embodiment is another embodiment of the first embodiment in which the selection criteria for the kind group to be produced ahead of schedule are changed to the kind group load ratio ρ described below. That is, in the first embodiment, the type group in which the satisfaction rate of the production instruction amount Ps of the type group with respect to the target production number Pso is the lowest is selected. In this example, the type to be produced ahead of schedule is determined by the type group load ratio ρ shown below. Select a group.

Type group load ratio ρ = (production instruction amount +
This ratio ρ indicates the load ratio for each type group when one lot of forward production is added, and the ratio ρ indicates the load ratio of each type group when one lot of advanced production is added. Since the production level is relatively compared with the target, it is possible to further reduce the variation in the production level for each product group after the advanced production.

In the above description, the candidate type k is the type k which is expected to have a production request at the closest time among the types belonging to the type group as described above. Therefore, in this example, as shown in FIG. 4, steps 621 to 623 are performed instead of steps 605 and 606 in FIG. That is, in step 621 following step 604, similarly to the above, among the varieties belonging to the varieties group, the varieties whose production request is predicted to be issued at the closest time are previously selected as candidate varieties k.

In step 622, the kind group load ratio ρ is calculated according to the above equation. Table 11
Indicates the kind group load ratio ρ based on the primary production instruction amount P1 before the production instruction amount is determined. That is, in the product group A, the product type a1 becomes the candidate product type k and the lot size is eight, so that the load ratio ρ is 1.
07, in the product group B, the product b1 becomes the candidate product k, and its lot size is 12, so the load ratio ρ is 1.10.

[0048]

[Table 11]

Then, in step 623, a product type group having the minimum product type group load ratio ρ is selected.
That is, based on Table 11, the product group load ratio ρ
Is finally selected as a kind group to be brought forward as in the first embodiment.

Other steps are described in the first embodiment.
As a result, as shown in Table 12, the same production instruction amount as in the first embodiment is determined. The right column of Table 12 shows the value of the product group load ratio ρ in the case where the forward production is further performed on the confirmed production instruction amount, and is not the load ratio for the confirmed production instruction amount. Others are the same as the first embodiment.

[0051]

[Table 12]

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a production instruction amount leveling device according to a first embodiment.

FIG. 2 is a flowchart showing a processing flow of the production instruction amount leveling device of the first embodiment.

FIG. 3 is a diagram showing a relationship between a change in stock of a product type and a predicted stock change, and an order prediction time according to the first embodiment.

FIG. 4 is a flowchart illustrating a flow of processing of a production instruction amount leveling device according to a second embodiment.

[Explanation of symbols]

11. . . 11. Type-specific inventory recording means (table), . . 12. Order trend recording means (table) by product type; . . 13. Type group recording means (table); . . 14. Production target recording means (table) for each product group, . . 20. Capability recording means (table) for each line, . . Arithmetic means,

Claims (2)

[Claims] 1. A production instruction leveling device for leveling a production instruction amount for a production line for prospectively producing a plurality of types in lot units, wherein a lot size of each type and a current inventory amount are determined. Type-specific inventory recording means for recording, type-specific order trend recording means for recording the trend of inventory changes or order trends for each type, and a type group with similar requirements for parts configuration or manufacturing line registered as the same type group Type group recording means for registering, proper type production target recording means for registering an appropriate number of production per time bucket for each type group, and line capacity recording for registering an appropriate production capacity per time bucket of the production line Means and the production schedule for the time bucket by increasing or decreasing the advance production plan for the production demand for each product type in the current time bucket. Calculating means for calculating the indicated quantity, wherein the calculating means subtracts the carry-over amount of the previously advanced production carried out from the current required production amount, corrects this in lot units, and corrects the primary production amount for each type. A first calculating means for calculating a production instruction amount, and integrating the primary production instruction amount for each type group, and selecting a type group in which the integrated value deviates most from an appropriate production target of the type group; Means for selecting a forwarded product type group, and a period until a lot production request is predicted to occur next for each product type belonging to the selected product type group based on the current inventory and the information of the product type order tendency recording means. Advancing production operation means for advancing the production of one lot of the type having the shortest prediction period and instructing production, and the above means until the production instruction amount for the line production capacity falls within a predetermined range. Control means for reversing the operation, and fixed production instruction amount recording means for recording the production instruction amount for each product type when the production instruction amount for the line production capacity is within a predetermined range. Characterized production instruction quantity leveling device. 2. The method according to claim 1, wherein the forwarded product group selecting means includes, for each product group, one lot of a product having a shortest period until a production request is predicted to occur next among products belonging to the product group. A production instruction leveling device characterized in that, in the case where the production instruction quantity is brought forward, a type group having the lowest ratio of the production instruction quantity to the production target quantity is selected.