Method for calculating the demand of a hull part container

Abstract

This invention provides a method for calculating the demand for containers for ship hull parts. It decomposes the entire production logistics process into eight key stages: work-in-process inventory in production, transshipment volume in the logistics transfer loop, storage volume in the storage area, secondary transfer and downstream usage in the usage stage, and recycling volume in the recycling stage. By calculating the container demand segment by segment, the total number of containers required by the system is finally obtained. Traditional methods rely on estimations based on management experience; this invention, through formulaic calculations, transforms demand forecasting into data-driven forecasting, reducing subjective bias. Furthermore, this invention's calculation method covers multiple departments, including production, warehousing, logistics, and recycling, promoting collaborative work among departments based on the same data standard. Based on the calculated values, targeted improvements can be implemented for high-percentage stages, such as reducing storage time and improving transfer efficiency, achieving cost reduction and efficiency improvement.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a method for calculating the demand for containers in ship hull parts. Background Technology

[0002] In the complex process of ship hull section production, various steel plates and profile parts, after being cut and processed, typically require centralized loading using specialized containers to achieve rapid, safe, and standardized hoisting and turnover. However, how to scientifically and accurately calculate the actual demand for these containers has long been a thorny problem in production site management. This issue is not simply a matter of quantity statistics, but is deeply related to the dynamic balance of the production system: on the one hand, it is directly constrained by the workshop's own capacity rhythm; on the other hand, it is closely linked to the inventory status of parts. In addition, the smooth progress of subsequent processes (such as section assembly), and whether there are any delays or waiting, will also adversely affect the release and return speed of containers, thus creating dynamic demand fluctuations.

[0003] Under traditional management models, container configuration often relies on experience-based estimations or excessive stockpiling, easily leading to two situations: either insufficient containers, causing parts to pile up on the ground and delaying transportation, affecting production continuity and on-site safety; or excessive idle containers, occupying a large amount of space and capital, and generating unnecessary maintenance and management costs. With the deepening of lean manufacturing concepts in the shipbuilding industry, the need for refined and data-driven management of the entire production process is becoming increasingly prominent. How to accurately match container resources to meet the needs of efficient production flow while minimizing waste and controlling costs has become one of the key aspects of improving the operational efficiency and effectiveness of shipyard workshops. Therefore, developing a container quantity calculation method that can comprehensively consider multiple variables and dynamically reflect actual needs is not only theoretically necessary but also has extremely urgent practical significance for the advancement of lean manufacturing. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for calculating the demand for hull parts containers, accurately calculating the demand for hull parts containers during production and circulation, and providing strong data support for lean production and efficient management.

[0005] To achieve the above and other related objectives, the present invention provides a method for calculating the demand for containers for ship hull parts, comprising the following steps:

[0006] S1: Calculation of average daily container demand; The average daily container demand is the average demand for containers for hull parts produced by daily cutting. Based on the annual production line schedule and monthly production plan, calculate the average number of monthly sections 'a'; determine the average number of containers required per section 'b' based on the designed hull pallet division; and calculate the average daily container output 'd' as the average daily container demand based on the average number of actual working days per month 'c'.

[0007]

[0008] S2: Calculation of Intrinsic Quantity for Part Cutting; The intrinsic quantity for part cutting is defined as the number of part containers required during the cutting production process. First, determine the daily cutting production time e, calculate the average production time f for part containers, determine the cutting production cycle g for all parts within the segment based on the production plan, calculate the average dwell time h for work-in-process part containers, determine the demand percentage y for part containers based on the designed hull pallet division, and calculate the intrinsic quantity j for part cutting.

[0009]

[0010]

[0011] j=d×h×y

[0012] Where g represents the average time from the start of cutting to completion of cutting all parts within the segment, h represents the average dwell time of the in-process parts container, and y represents the total time from the container entering the production line to leaving the production line.

[0013] Optionally, the following steps may also be included:

[0014] S3: Calculation of in-span to out-of-span transfer volume. In-span to out-of-span transfer volume is defined as the volume m of circulating containers transferred from the cutting production span to the outer storage area. The interval k from departure to return during the transfer of parts containers from in-span to out-of-span is calculated. It is set that each vehicle can only carry one container per transfer. Since the parts inside the containers are combined during transfer, the ratio of the number of containers before combination to the number of containers after combination is... , .

[0015] Optionally, the following steps are also included: S4: Calculation of cutting stockpile volume, where the cutting stockpile volume is the amount of containers filled with parts stored in the parts warehouse after cutting is completed. First, the average dwell time n of the parts containers is calculated, and then the cutting stockpile volume is calculated. .

[0016] Optionally, the following steps are also included: S5: Calculation of the quantity from the cutting yard to the downstream process. The quantity from the cutting yard to the downstream process is defined as the number of parts containers transferred from the cutting yard to the downstream process. This is consistent with the calculation method for the quantity transferred from within the span to outside the span in S3. Based on the statistical interval p of the parts containers from departure to return during the transfer from the cutting yard to the downstream process, it is set that each vehicle can only carry one container during the transfer. Since the parts inside the containers are combined during the transfer, the ratio of the number of containers before merging to the number of containers after merging is... Calculate the amount of cutting the stockpile to the next stage. .

[0017] Optionally, the process also includes the following step: S6: Calculation of downstream usage, where downstream usage is defined as the number of parts containers in use in the downstream process. The downstream usage is calculated based on the statistically analyzed average pallet occupancy time r in the downstream process. .

[0018] Optionally, the following steps are also included: S7: Calculation of empty container recovery quantity. The empty container recovery quantity is defined as the quantity of empty containers recovered during the process after parts are unloaded. This is consistent with the calculation method of the transfer quantity from inside the span to outside the span in S3. The empty container recovery quantity is calculated based on the statistical interval t from departure to return during the parts container recovery and transfer. .

[0019] Optionally, the following steps may also be included:

[0020] S8: Calculation of total demand for parts containers. The total demand for parts containers is the sum of the demand calculated at each stage. The total demand for parts containers is w.

[0021]

[0022] Where x1=j, x2=m, x3=o, x4=q, x5=s, x6=v.

[0023] As described above, this invention provides a method for calculating the demand for containers for ship hull parts. It decomposes the entire production logistics process into eight key stages: work-in-process inventory in production, transshipment volume in the logistics transfer loop, storage volume in the storage stage, secondary transshipment and downstream usage in the usage stage, and recycling volume in the recycling stage. By calculating the container demand segment by segment, the total number of containers required by the system is finally obtained. Traditional methods rely on estimations based on management experience; this invention, through formulaic calculations, transforms demand forecasting into data-driven forecasting, reducing subjective bias. Furthermore, the calculation method of this invention covers multiple departments, including production, warehousing, logistics, and recycling, promoting collaborative work among departments based on the same data standard. Based on the calculated values, targeted improvements can be implemented for high-percentage stages, such as reducing storage time and improving transshipment efficiency, achieving cost reduction and efficiency improvement. Attached Figure Description

[0024] Figure 1 The diagram shown is a flowchart of the calculation method of the present invention.

[0025] Figure 2 The diagram shown illustrates the calculation principle of the transfer volume in this invention.

[0026] Figure 3 This diagram illustrates the calculation principle of the cutting stockpile volume in this invention. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0029] like Figure 1 As shown, the present invention provides a method for calculating the demand for containers for ship hull parts, comprising the following steps:

[0030] S1: Calculation of Daily Average Container Demand. The daily average container demand refers to the average demand for containers for hull parts generated daily during cutting. Based on the annual production line schedule and monthly production plan, the average monthly number of sections *a* (units) is calculated; based on the designed hull pallet division, the average number of containers required per section *b* (units) is determined; and based on the average monthly actual working days *c* (units), the average daily container (pallet) output *d* (units) is calculated.

[0031]

[0032] S2: Calculation of the internal quantity of parts cutting across the production span. The internal quantity of parts cutting across the production span refers to the number of parts containers required during the cutting process. First, determine the daily production time e (in minutes), calculate the average production time f (in minutes / unit) for parts containers, determine the production cycle g (in days) for all parts cutting within the segment based on the production plan, calculate the average downtime h (in days) for parts containers in production, determine the demand percentage y for parts containers based on the designed hull pallet division, and calculate the internal quantity j (in units) of parts cutting across the production span.

[0033]

[0034]

[0035] =d×h×y

[0036] Wherein, the average production time f represents how many minutes it takes to produce one container, that is, the time required to produce all the parts in one container; g represents the average time from the start of cutting to completion of all parts in the segment; the average dwell time h of the in-process parts containers represents the total time from the container entering the production line to leaving the production line; g / b is the average dwell time of each container on the production line; the demand ratio y of parts containers represents the proportion of parts that need to be contained in containers, because not all parts need containers, only some need them; d×h represents the number of containers produced on the production line within the average dwell time h (specifically, how many days). For example, if there is a one-day dwell time, d containers are needed; if there is a two-day dwell time, 2d containers are needed.

[0037] S3: Calculation of in-span to out-of-span transfer volume. This in-span to out-of-span transfer volume refers to the volume of circulating containers transferred from the cutting production span to the outer storage area. It is necessary to calculate the interval k (minutes / container) from departure to return during the in-span to out-of-span transfer of parts containers. It is assumed that each vehicle can only carry one container per transfer. Since the parts inside the containers are combined during transfer, the ratio of the number of containers before combination to the number of containers after combination is... This represents the container's capacity for consolidation and expansion. During transportation, parts from multiple containers may be combined into fewer containers for transport, reducing transportation costs. This can be understood as a merging factor for container capacity. Then, the in-span to out-of-span transfer volume m (in units) is calculated based on the Milk-Run calculation model (see...). Figure 2 ):

[0038]

[0039] Where k represents the cycle time of the transfer container, i.e., the time interval from departure to return, and f represents the time required for the production line to produce all the parts in one container. To meet the production rhythm, the produced containers need to be transferred immediately. k / f gives the number of parallel transfers required. For example, when the container production time is 1 day and the transfer time is 2 days, then 2 parallel transfers are needed to meet the immediate transfer requirement; then divide by... The combined number of transfers is obtained; the reason for multiplying by 2 at the end is to consider the worst-case scenario requiring two cycles: when the container is just empty, if the vehicle has just left, it needs to wait for a full cycle before the vehicle returns to pick up the empty container. Then, it needs to wait another cycle before the vehicle can return with the full container. Therefore, sufficient redundancy needs to be designed to meet the container capacity required for two two-transport cycles.

[0040] S4: Calculation of cutting stockpile volume. The cutting stockpile volume refers to the amount of containers filled with parts stored in the parts warehouse after cutting is completed. First, calculate the average storage period n (in days) of the parts containers. Then, according to Little's Law (see...),... Figure 3 Cutting stockpile quantity o (units):

[0041]

[0042] S5: Calculation of the quantity from the cutting yard to the downstream process. This quantity refers to the number of parts containers transferred from the cutting yard to the downstream process. The calculation method is consistent with S3, which calculates the quantity from within the span to outside the span. The Milk-Run calculation model is used, based on the statistically calculated interval p (minutes / container) between the departure and return of parts containers from the cutting yard to the downstream process. It is set that each vehicle can only carry one container during transfer. Since the parts inside the containers are combined during transfer, the ratio of the number of containers before combination to the number of containers after combination is... Calculate the quantity q (units) of cutting stockpile to downstream processing:

[0043]

[0044] Similar to the calculation formula for m above, this requires meeting the production cycle time and having sufficient redundancy.

[0045] S6: Calculation of downstream usage, where downstream usage refers to the number of parts containers in use in the downstream process, based on the statistical average pallet occupancy time r (per day) and downstream usage s (per unit):

[0046]

[0047] S7: Calculation of empty container recovery volume. The empty container recovery volume refers to the number of empty containers recovered during the part unloading process. This calculation method is consistent with that used in S3 for the in-span to out-of-span transfer volume. Using the Milk-Run calculation model, based on the statistical interval t (minutes / container) during part container recovery and transfer from departure to return, and assuming that each vehicle can only carry one container per transfer, the empty container recovery volume v (unit: container) is calculated.

[0048]

[0049] Since the containers here are empty, there is no need to consider the issue of merging and loading parts; it is sufficient to ensure that the recycled empty containers meet the production cycle time.

[0050] S8: Calculation of total demand for parts containers. The total demand for parts containers is the sum of the demand for parts containers calculated at each stage. The total demand for parts containers is w (units):

[0051]

[0052] In the formula, x1=j, x2=m, x3=o, x4=q, x5=s, x6=v.

[0053] The calculation process of each step is described in detail below through specific embodiments.

[0054] Example 1

[0055] According to the method for calculating the demand for ship hull parts containers provided by the present invention, the following eight steps are performed: 1. Daily average container demand, 2. Manufacturing quantity within the cutting span of the parts, 3. Transfer quantity from within the span to outside the span, 4. Cutting stockpile quantity, 5. Quantity from the cutting stockpile to the downstream process, 6. Quantity in use in the downstream process, 7. Quantity of empty containers recycled, 8. Total demand for parts containers.

[0056] S1: Average daily demand for containers.

[0057] The average daily container demand, i.e., the average demand for containers for hull parts produced daily, is calculated as follows: based on the annual production line schedule and monthly production plan, the average monthly number of sections, a, is 216 (units); based on the designed hull pallet division, the average number of containers required per section, b, is determined to be 33 (units); and based on the average monthly actual working days, c, is 26 (units), the average daily pallet output, d (units), is calculated.

[0058]

[0059] S2: Part cutting spans internal quantity.

[0060] The part cutting spans the internal quantity, that is, the number of part containers required in the cutting production process. First, determine the daily cutting production time e as 960 (units of minutes), and calculate the average production time f (units of minutes / piece) for part containers.

[0061]

[0062] Based on the production plan, the production cycle g for cutting all parts within the segment is determined to be 6.41 (per day). Calculate the average dwell time h (per day) for the work-in-process parts containers.

[0063]

[0064] Based on the design of the hull pallet division, the required proportion of parts containers (y) is determined to be 56.9%. Calculate the internal quantity (j, per unit) of parts within the cutting span.

[0065]

[0066] S3: Intra-span to inter-span transfer volume, which refers to the flow of parts transferred from the cutting production span to the outer storage area. The interval time k for part container transfer needs to be calculated as 2.4 (minutes / piece), with a consolidation coefficient. Given a value of 1.5, calculate the transshipment volume m (units) from within the span to outside the span, based on the Milk-Run calculation model (see...). Figure 2 ):

[0067]

[0068] S4: Cutting stockpile quantity, which refers to the quantity of containers filled with parts stored in the parts warehouse after cutting. First, calculate the average storage period n of the parts containers as 9 (in days). Then, according to Little's Law (see...),... Figure 3 Cutting stockpile quantity o (units):

[0069]

[0070] S5: Quantity from cutting yard to downstream processing. This quantity refers to the number of parts containers transferred from the cutting yard to the downstream processing stage. The calculation method is consistent with S3, which calculates the quantity transferred from within the span to outside the span. The Milk-Run calculation model is used, and the interval time p for the statistically analyzed parts container transfer is 2.8 (minutes / container). A consolidation coefficient is applied. Given a value of 1.5, calculate the quantity q (units) of cutting the stockpile to the downstream stage:

[0071]

[0072] S6: Downstream usage, which refers to the number of parts containers in use in the downstream process. Based on the statistical average pallet occupancy time r in the downstream process is 0.3 (per day), the downstream usage quantity s (per unit):

[0073]

[0074] S7: Empty container recovery quantity. The empty container recovery quantity refers to the number of empty containers recovered during the process after all parts have been unloaded. This is calculated using the same method as S3, which calculates the in-span to out-of-span transfer quantity. The Milk-Run calculation model is used, and based on the statistically calculated interval t for part container transfer as 2.8 minutes per container, the empty container recovery quantity v is calculated to be 1.6 units.

[0075]

[0076] S8: Total demand for parts containers, which is the sum of the demand for parts containers calculated at each stage, and the total demand for parts containers w (in units):

[0077]

[0078] In the formula, x1=j, x2=m, x3=o, x4=q, x5=s, x6=v.

[0079]

[0080] In summary, this invention provides a method for calculating the demand for containers for ship hull parts. It decomposes the entire production logistics process into eight key stages: work-in-process inventory in production, transshipment volume in the logistics transfer loop, storage volume in the storage area, secondary transshipment and downstream usage in the usage stage, and recycling volume in the recycling stage. By calculating container demand segment by segment, the total number of containers required by the system is finally obtained. Traditional methods rely on estimations based on management experience; this invention, through formulaic calculations, transforms demand forecasting into data-driven forecasting, reducing subjective bias. Furthermore, the calculation method of this invention covers multiple departments, including production, warehousing, logistics, and recycling, promoting collaborative work among departments based on the same data standard. Based on the calculated values, targeted improvements can be implemented for high-percentage stages, such as reducing storage time and improving transshipment efficiency, achieving cost reduction and efficiency improvement.

[0081] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for calculating the demand for containers in ship hull parts, characterized in that, Includes the following steps: S1: Calculation of average daily container demand; The average daily container demand is the average demand for containers for hull parts produced by daily cutting. Based on the annual production line schedule and monthly production plan, calculate the average number of monthly sections 'a'; determine the average number of containers required per section 'b' based on the designed hull pallet division; and calculate the average daily container output 'd' as the average daily container demand based on the average number of actual working days per month 'c'. S2: Calculation of Intrinsic Quantity for Part Cutting; The intrinsic quantity for part cutting is defined as the number of part containers required during the cutting production process. First, determine the daily cutting production time e, calculate the average production time f for part containers, determine the cutting production cycle g for all parts within the segment based on the production plan, calculate the average dwell time h for work-in-process part containers, determine the demand percentage y for part containers based on the designed hull pallet division, and calculate the intrinsic quantity j for part cutting. =d×h×y Where g represents the average time from the start of cutting to completion of cutting all parts within the segment, h represents the average dwell time of the in-process parts container, and y represents the total time from the container entering the production line to leaving the production line.

2. The method for calculating the demand for ship hull component containers according to claim 1, characterized in that, It also includes the following steps: S3: Calculation of in-span to out-of-span transfer volume. In-span to out-of-span transfer volume is defined as the volume m of circulating containers transferred from the cutting production span to the outer storage area. The interval k from departure to return during the transfer of parts containers from in-span to out-of-span is calculated. It is set that each vehicle can only carry one container per transfer. Since the parts inside the containers are combined during transfer, the ratio of the number of containers before combination to the number of containers after combination is... , .

3. The method for calculating the demand for ship hull component containers according to claim 1, characterized in that, It also includes the following steps: S4: Calculation of cutting stockpile volume. The cutting stockpile volume is the amount of containers filled with parts stored in the parts warehouse after cutting is completed. First, calculate the average dwell time n of the parts containers, then calculate the cutting stockpile volume. .

4. The method for calculating the demand for ship hull component containers according to claim 1, characterized in that, It also includes the following steps: S5: Calculation of the quantity from the cutting yard to the downstream process. This quantity is defined as the number of parts containers transferred from the cutting yard to the downstream process. The calculation method is consistent with S3's calculation of the quantity transferred from within the span to outside the span. Based on the statistically recorded interval 'p' between departure and return of parts containers from the cutting yard to the downstream process, it is set that each vehicle can only carry one container during transfer. Since the parts inside the containers are combined during transfer, the ratio of the number of containers before combination to the number of containers after combination is... Calculate the amount of cutting the stockpile to the next stage. .

5. The method for calculating the demand for ship hull component containers according to claim 1, characterized in that, It also includes the following steps: S6: Calculation of downstream usage. Downstream usage is defined as the number of parts containers in use during downstream processes. It is calculated based on the average pallet occupancy time (r) during downstream processes. .

6. The method for calculating the demand for ship hull component containers according to claim 1, characterized in that, It also includes the following steps: S7: Calculation of empty container recovery volume. The empty container recovery volume is defined as the number of empty containers recovered after parts are unloaded. This calculation method is consistent with S3's calculation of the volume transferred from within the span to outside the span. The empty container recovery volume is calculated based on the statistically recorded interval t from departure to return during the parts container recovery and transfer process. .

7. The method for calculating the demand for ship hull component containers according to claim 1, characterized in that, It also includes the following steps: S8: Calculation of total demand for parts containers. The total demand for parts containers is the sum of the demand calculated at each stage. The total demand for parts containers is w. Where x1=j, x2=m, x3=o, x4=q, x5=s, x6=v.

Images