Abstract:
A technique that can make a flexible production plan adaptable to circumstances of a production request-issuing side. 
     A producible quantity calculation part performs Material Requirements Planning for obtaining a producible quantity and a possible production date, with respect to production request information that has at least one production request specifying a requested production quantity of a product, a requested production date, and a priority. If the producible quantity calculation part judges that a requested production quantity in one production request cannot be produced by the requested production date in that production request, then the producible quantity calculation part postpones the requested production date to a later date according to a plurality of methods, to obtain producible quantities and possible production dates. The producible quantity calculation part generates image data that display, in a table, the producible quantities and possible production dates obtained by the methods.

Description:
[0001]    The present application claims a priority from Japanese application no. 2007-038250 filed on Feb. 19, 2007, the content of which is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a technique associated with Material Requirements Planning for obtaining the producible quantity and the possible production date with respect to production request information. 
         [0003]    A technique is known that employs Material Requirements Planning (hereinafter, referred to as MRP) for calculating a producible quantity with respect to a requested production quantity, in order to make a production plan. 
         [0004]    For example, the technique described in Patent Document 1 calculates a producible quantity, and makes a production plan in which a shortage of a part does not occur since the requested production date is postponed to a later date (postponement processing) if there is a lack of a part in producing the requested quantity. 
         [0005]    Patent Document 1: Japanese Un-examined Patent Application Laid-Open No. 2002-244717 
         [0006]    The technique described in Patent Document 1 makes a production plan that does not cause a shortage of a part with respect to a production request. The producible quantity, however, is calculated on the basis of a specific method of postponement processing or a specific priority order, so that it is impossible to make a flexible production plan adaptable to the circumstances of the production request-issuing side. 
         [0007]    Thus, an object of the present invention is to provide a technique that can make a flexible production plan adaptable to the circumstances of the production request-issuing side. 
       SUMMARY OF THE INVENTION 
       [0008]    To solve the above problem, the present invention provides a technique that can calculate producible quantities by employing a plurality of methods of postponement processing or kinds of priority order to make a plurality of production plans, and output those production plans in a tabular form. 
         [0009]    For example, the present invention provides a calculation apparatus for performing Material Requirements Planning by receiving production request information that has at least one production request specifying a requested production quantity of a product, a requested production date and a priority, and by obtaining a producible quantity and a possible production date according to the priority, with respect to the production request information, wherein: the calculation apparatus comprises a control part that performs: postponement processing, in which a plurality of methods of postponing a requested production date to a later date are determined in advance in the Material Requirements Planning, each method being performed if it is judged that a requested production quantity in one production request cannot be produced by the requested production date in the one production request, and the Material Requirements Planning is performed with the requested production date changed to the later date in the one production request according to each of the plurality of methods, and processing of changing a requested production date in the one production request to a later date is repeated until all the requested production quantities in the one production request can be produced; and processing of generating image data that display, in a table, the producible quantities and the possible production dates calculated by the postponement processing for each of the methods with respect to the production request information. 
         [0010]    According to the present invention, producible quantities are calculated according to a plurality of postponing methods and kinds of priority order, and a plurality of production plans are outputted in a tabular form. Thus, a production request-issuing side can select a suitable production plan out of a plurality of production plans. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic diagram showing a calculation apparatus as a first embodiment of the present invention; 
           [0012]      FIG. 2  is a schematic diagram showing a part table; 
           [0013]      FIG. 3A  is a schematic diagrams showing makeup of products X and Y; 
           [0014]      FIG. 3B  is a schematic diagrams showing makeup of products X and Y; 
           [0015]      FIG. 4  is a schematic diagram showing a lead time table; 
           [0016]      FIG. 5  is a schematic diagram showing an initial stock table; 
           [0017]      FIG. 6  is a schematic diagram showing an incoming-stock table; 
           [0018]      FIG. 7  is a schematic diagram showing a production plan table; 
           [0019]      FIG. 8  is a schematic view showing a display image; 
           [0020]      FIG. 9  is a schematic diagram showing a production request table; 
           [0021]      FIG. 10  is a schematic diagram showing method information; 
           [0022]      FIG. 11A  is a schematic diagrams for explaining a postponing method  1 ; 
           [0023]      FIG. 11B  is a schematic diagrams for explaining a postponing method  1 ; 
           [0024]      FIG. 12A  is a schematic diagram for explaining a postponing method  2 ; 
           [0025]      FIG. 12B  is a schematic diagram for explaining a postponing method  2 ; 
           [0026]      FIG. 13  is a schematic block diagram showing a computer; 
           [0027]      FIG. 14  is a flowchart showing processing performed in the calculation apparatus; 
           [0028]      FIG. 15  is a schematic diagram showing a calculation apparatus as a second embodiment of the present invention; 
           [0029]      FIG. 16  is a schematic view showing a display image; 
           [0030]      FIG. 17  is a flowchart showing processing performed in the calculation apparatus; 
           [0031]      FIG. 18  is a schematic diagram showing a calculation apparatus as a third embodiment of the present invention; 
           [0032]      FIG. 19  is a schematic view showing a display image; 
           [0033]      FIG. 20  is a flowchart showing processing performed in the calculation apparatus; and 
           [0034]      FIG. 21  is a schematic block diagram showing a calculation system  400 . 
       
    
    
     DETAILED DESCRIPTION 
       [0035]      FIG. 1  is a schematic diagram showing a calculation apparatus  100  as a first embodiment of the present invention. 
         [0036]    The calculation apparatus  100  comprises a storage part  110 , a control part  120 , an input part  130 , an output part  140  and a sending/receiving part  150 . 
         [0037]    The storage part  110  comprises a part information storage area  111 , a lead time information storage area  112 , an initial stock information storage area  113 , an incoming-stock information storage area  114 , a production plan information storage area  115  and a display information storage area  116 . 
         [0038]    The part information storage area  111  stores information that specifies a part (i.e. an intermediate product or member) as a component of a product or another part and its quantity required to construct one unit of that product or part. 
         [0039]    For example, the part information storage area  111  stores a part table  111   a  as shown in  FIG. 2  (a schematic diagram showing the part table  111   a ). 
         [0040]    The part table  111   a  has a parent item field  111   b , a child item field  111   c  and a number field  111   d.    
         [0041]    The parent item field  111   b  stores information specifying a product or part, of which the part specified in the child item field  111   c  is a component member. Here, the parent item field  111   b  stores identification information (a name or an ID) that identifies a product or a part. 
         [0042]    The child item field  111   c  stores information specifying a part (an intermediate product or member) that is a component member of the product or part specified in the parent item field  111   b . Here, the child item field  111   c  stores identification information (a name or an ID) that identifies a part. 
         [0043]    The number field  111   d  stores information specifying a required quantity of the part specified in the child item field  111   c  for constructing one unit of the product or part specified in the parent item field  111   b.    
         [0044]    For example, in the present embodiment, as shown in  FIG. 3  (a schematic diagram showing makeup of products X and Y), the product X is constructed by combining one intermediate product A and one intermediate product B. The intermediate product A is constructed by combining two members a, and one member b. Further, the intermediate product B is constructed by combining one member c, and one member d (see  FIG. 3A ). 
         [0045]    Further, the product Y is constructed by combining one intermediate product A and one member e. As stated above, the intermediate product A is constructed by combining two members a, and one member b. 
         [0046]    In the present embodiment, parts are intermediate products and members that constitute a product as the target of production. Each intermediate product is made by the producer of the product by combining members purchased from dealers, and used as a part of the final product. Further, each member is purchased by the producer of the product from a dealer and used as a part of the product or an intermediate product. 
         [0047]    In the present embodiment, when identification information identifying the product X is stored in the parent item field  111   b , then identification information identifying the intermediate product A or B is stored in the child item field  111   c  of the line corresponding to that parent item field  111   b . For each of the intermediate products A and B, the corresponding number field  111   d  stores “1”. 
         [0048]    Further, in cases where the identification information identifying the intermediate product A is stored in the parent item field  111   b , the child item field  111   c  corresponding to that parent item field  111   b  stores identification information identifying the member a or b. The number field  111   d  corresponding to the member a stores “2”, and the number field  111   d  corresponding to the member b stores “1”. 
         [0049]    Further, in cases where the identification information identifying the intermediate product B is stored in the parent item field  111   b , the child item field  111   c  corresponding to that parent item field  111   b  stores identification information identifying the member c or d. For each of the members c and d, the corresponding number field  111   d  stores “1”. 
         [0050]    Further, when identification information identifying the product Y is stored in the parent item field  111   b , then identification information identifying the intermediate product A or the member e is stored in the child item field  111   c  of the line corresponding to that parent item field  111   b . For each of the intermediate product B and the member e, the corresponding number field  111   d  stores “1”. 
         [0051]    The lead time information storage area  112  stores information that specifies a production lead time of a product or a part or a procurement lead time of a part. 
         [0052]    For example, the lead time information storage area  112  stores a lead time table  112   a  as shown in  FIG. 4  (a schematic diagram showing the lead time table  112   a ). 
         [0053]    The lead time table  112   a  has an item field  112   b , a workplace field  112   c  and a lead time field  112   d.    
         [0054]    The item field  112   b  stores identification information that identifies a product or a part. 
         [0055]    The workplace field  112   c  stores information that identifies a workplace in which the product or the part is produced in cases where the product or the part is produced, or a part maker from which the part is procured in cases where the part is procured from the outside. 
         [0056]    The lead time field  112   d  stores a production lead time (i.e. a period from input of parts to completion) in cases where the product or the part is produced, or a procurement lead time (i.e. a period from order of the part to procurement) in cases where the part is procured. This field is expressed in units of days, although this mode is not restrictive. 
         [0057]    The initial stock information storage area  113  stores information that specifies a quantity of a product or a part held in stock. In the present embodiment, this area  113  stores information indicating stock (initial stock) at the first date of a production plan calculated by the calculation apparatus  100 . 
         [0058]    For example, the initial stock information storage area  113  stores an initial stock table  113   a  as shown in  FIG. 5  (a schematic diagram showing the initial stock table  113   a ). 
         [0059]    The initial stock table  113   a  has an item field  113   b  and an initial stock field  113   c.    
         [0060]    The item field  113   b  stores identification information that identifies a product or a part. 
         [0061]    The initial stock field  113   c  stores information that specifies a stock quantity (a quantity of an initial stock at the first date of a production plan calculated by the calculation apparatus  100 ) of the product or part specified in the item field  113   b.    
         [0062]    The incoming-stock information storage area  114  stores information that specifies an acceptance date and an incoming-stock quantity of a part procured from the outside. 
         [0063]    For example, the incoming-stock information storage area  114  stores an incoming-stock table  114   a  as shown in  FIG. 6  (a schematic diagram showing the incoming-stock table  114   a ). 
         [0064]    The incoming-stock table  114   a  has a date field  114   b , an item field  114   c  and an incoming-stock quantity field  114   d.    
         [0065]    The date field  114   b  stores information that specifies an acceptance date of a part procured from the outside. In the present embodiment, information specifying year/month/day of receiving a new stock of a part is stored as the information specifying an acceptance date. 
         [0066]    The item field  114   c  stores identification information that identifies the part procured from the outside. 
         [0067]    The incoming-stock quantity field  114   d  stores an incoming-stock quantity of the part specified in the item field  114   c , which is stored at the date specified in the date field  114   b.    
         [0068]    The production plan information storage area  115  stores information that specifies a production plan generated by the below-described producible quantity calculation part  121 . Here, a production plan specifies the number of products that can be produced by a specific date at least for each product. 
         [0069]    For example, the production plan information storage area  115  stores a production plan table  115   a  as shown in  FIG. 7  (a schematic diagram showing the production plan table  115   a ) for each postponing method. 
         [0070]    The production plan table  115   a  has a product name field  115   b  and a production plan field  115   c.    
         [0071]    The product name field  115   b  stores identification information that specifies a product. In the present embodiment, the product name field  115   b  stores a name of a product. 
         [0072]    The production plan field  115   c  stores information that specifies dates and respective quantities producible at the dates for each product specified in the product name field  115   b.    
         [0073]    The display information storage area  116  stores display information generated in the below-described display information generation part  122 . Here, display information provides, in a table, information that specifies the requested production quantity for each date, which is specified in the below-described production request information, and production quantity that is judged to be producible according to a specific postponing method for each product. 
         [0074]    For example, the display information storage area  116  stores information that specifies a display image as shown in  FIG. 8  (a schematic view showing the display image  116   a ). 
         [0075]    The display image  116   a  has a product field  116   b , a type field  116   c  and a production plan field  116   d.    
         [0076]    The product field  116   b  stores identification information that identifies a product. Here, a name of a product is stored as identification information. 
         [0077]    The type field  116   c  stores identification information that identifies a production request or a postponing method. In the present embodiment, the type field  116   c  stores a character string “Production Request” in cases where the line concerned indicates requested production quantities. On the other hand, the type field  116   c  stores a character string “Method n” in cases where the line concerned indicates producible quantities calculated according to an n-th postponing method (n is a natural number, i.e. an identification number for identifying a postponing method). 
         [0078]    The production plan field  116   d  stores requested production quantities or producible quantities by respective dates. That is, in a line in which the type field  116   c  stores the character string “Production Request”, the production plan field  116   d  stores requested production quantities by respective dates. On the other hand, in a line in which the type field  116   c  stores a character string “Method n”, the production plan field  116   d  stores quantities producible by respective dates. 
         [0079]    Here, numbers in parentheses shown in the production plan field  116   d  indicate cumulative quantities. 
         [0080]    The control part  120  comprises a producible quantity calculation part  121  and a display information generation part  122 . 
         [0081]    The producible quantity calculation part  121  performs MRP processing on the basis of production request information acquired through the below-described input part  130  or sending/receiving part  150 . 
         [0082]    It is assumed that the production request information required for performing the MRP processing includes at least a date at which a product is required, a requested quantity, and priority. 
         [0083]    For example, in this regard, in the present embodiment, a production request table  121   a  as shown in  FIG. 9  (a schematic diagram showing the production request table  121   a ) is inputted to the producible quantity calculation part  121  through the input part  130  or the sending/receiving part  150 . 
         [0084]    The production request table  121   a  has a requested date field  121   b , a product field  121   c , a requested quantity field  121   d  and a priority field  121   e.    
         [0085]    The requested date field  121   b  stores information that specifies a date at which a product specified in the below-described product field  121   c  is required. In the present embodiment, this field stores a date expressed as “year/month/day”, although this mode is not restrictive. 
         [0086]    The product field  121   c  stores information that specifies identification information (a name or an ID) identifying a product whose production is requested. 
         [0087]    The requested quantity field  121   d  stores information that specifies a quantity required by the date specified in the requested date field  121   b  with respect to the product specified in the product field  121   c.    
         [0088]    The priority field  121   e  stores information that specifies the priority of the production request specified in the line concerned. In the present embodiment, the priority field  121   e  stores a natural number, i.e. a sequential number starting from “1”, as the information specifying the priority, although this mode is not restrictive. 
         [0089]    In the MRP processing performed by the producible quantity calculation part  121 , a product, a requested date and a requested quantity are specified in the order of priority, referring to the priority field  121   e  of the production request table  121   a.    
         [0090]    The producible quantity calculation part  121  confirms the stock quantity of a product specified in the production request table  121   a , referring to the initial stock table  113   a . If there is a stock, the necessary and maximum quantity of the stock is allocated to cover the requested quantity, and the quantity of the allocated stock is subtracted from the initial stock table  113   a . In cases where the requested quantity specified in the production request table  121   a  is all satisfied by the stock, the producible quantity calculation part  121  deals with the production request that is next in priority. 
         [0091]    On the other hand, in cases where the requested quantity specified in the production request table  121   a  is not satisfied by the stock, the producible quantity calculation part  121  specifies the lead time of the product in question from the lead time table  112   a . When the period from the current date to the requested date is longer than or equal to the lead time, parts of the product in question are specified from the part table  111   a . On the other hand, when the period from the current date to the requested date is shorter than the lead time, the quantity that is not covered by the stock is specified. 
         [0092]    Then, in cases where the period from the current date to the requested date is longer than or equal to the lead time, the producible quantity calculation part  121  allocates the stock of the parts specified in the part table  111   a  or the quantities of incoming-stocks of parts specified in the incoming-stock table  114   a    
         [0093]    For example, in cases where the period from the current date and the requested date is longer than or equal to the lead time, the producible quantity calculation part  121  specifies the stock of the parts (which are specified in the part table  111   a ) by the initial stock table  113   a , and allocates the required quantities, and subtracts the allocated quantities from the initial stock table  113   a . Here, in cases where all the stock concerned satisfy the quantities required for assembling the product, the producible quantity calculation part  121  deals with the production request that is next in priority. 
         [0094]    On the other hand, in cases where not all the stock concerned satisfies the quantities required for assembling the product, the producible quantity calculation part  121  specifies whether the part in question is an intermediate product or a member by means of the part table  111   a . When the part in question is a member, the producible quantity calculation part  121  specifies the acceptance date of the member in question by means of the incoming-stock table  114   a . When the period from the acceptance date to the requested date is longer than (or equal to) the lead time of the product, the producible quantity calculation part  121  allocates the necessary and maximum quantity of the part in question and subtracts the allocated quantity from the incoming-stock table  114   a . Here, in cases where all the incoming-stock quantities concerned satisfy the quantities required for assembling the product, the producible quantity calculation part  121  deals with the production request that is next in priority. 
         [0095]    On the other hand, in cases where not all the incoming-stock quantities concerned satisfy the quantities required for assembling the product, the producible quantity calculation part  121  specifies the lead time of the member in question by means of the lead time table  112   a . When the period from the current date to the requested date is longer than or equal to the lead time of the member, the producible quantity calculation part  121  deals with the production request that is next in priority. 
         [0096]    On the other hand, in cases where the period from the current date to the requested date is shorter than the lead time of the member, the producible quantity calculation part  121  specifies the non-producible quantity of the product. 
         [0097]    Further, in cases where not all the stock concerned satisfies the quantities required for assembling the product and the part in question (i.e. the part whose stock is deficient) is an intermediate product, then the producible quantity calculation part  121  specifies the lead time of the intermediate product in question from the lead time table  112   a . When the period from the current date to the requested date is longer than (or equal to) the lead time of the intermediate product, the producible quantity calculation part  121  specifies the parts of the intermediate product in question from the part table  111   a . On the other hand, when the period from the current date to the requested date is shorter than the lead time of the intermediate product, the producible quantity calculation part  121  specifies the non-producible quantity of the product. 
         [0098]    Then, when the period from the current date to the requested date is longer than (or equal to) the lead time of the intermediate product, the producible quantity calculation part  121  specifies, from the initial stock table  113   a , the stock of the parts specified by the part table  111   a , and allocates the necessary and maximum quantities of the stock in question. The producible quantity calculation part  121  subtracts the allocated quantities from the initial stock table  113   a . Here, in cases where all the stock concerned satisfies the quantities required for assembling the intermediate product, the producible quantity calculation part  121  deals with the production request that is next in priority. 
         [0099]    On the other hand, in cases where not all the stock concerned satisfies the quantities required for assembling the intermediate product, the producible quantity calculation part  121  specifies whether the part in question is an intermediate product or a member, by means of the part table  111   a , and repeats processing similar to the above-described processing. 
         [0100]    In the above-described MRP processing, when there is a quantity that cannot be produced by the date specified by the production request information among the quantities specified by the production request information, the producible quantity calculation part  121  performs postponement processing according to a predetermined postponing method. 
         [0101]    In the present embodiment, input of method information specifying a postponing method is received through the below-described input part  130  or sending/receiving part  150 , and postponement processing according to the postponing method corresponding to the received method information is performed. 
         [0102]    For example, in the present embodiment, as the method information received through the below-described input part  130  or sending/receiving part  150 , method information  122   a  as shown in  FIG. 10  (a schematic diagram showing the method information  122   a ) is inputted. 
         [0103]    The method information  122   a  stores information that specifies identification information (a name or an ID) for identifying each postponing method. 
         [0104]    As the postponing method, the present embodiment employs, for example, a method  1  or a method  2  described in the following. 
         [0105]      FIG. 11  is a schematic diagram for explaining a postponing method  1 . 
         [0106]    Here, the postponing method  1  generates a new production request that is next in priority to the production request that has been judged to be non-producible. At that level of priority, the requested date for the requested quantity that has been judged to be non-producible is postponed step by step until the requested quantity becomes producible. 
         [0107]    For example, with respect to the production request of priority “2” in the production request information shown in FIG.  11 A, if the producible quantity calculation part  121  judges that only “17” can be produced out of the requested quantity “20”, then the producible quantity calculation part  121  generates a new production request that is next in priority (here, priority “3”) to the production request that has been judged to be non-producible, such that a new requested date is the date (here, “2006/04/02”) next to the requested date of the production request that has been judged to be non-producible, and a new requested quantity (here, “3”) is the original requested quantity that was judged to be non-producible, as in the production request information shown in  FIG. 11B . Further, the priorities of the production requests that have lower priorities than the priority of the production request that has been judged to be non-producible, are each lowered by one. 
         [0108]    With respect to the new production request information generated as described above, the producible quantity calculation part  121  performs the MRP processing again, to judge whether the newly-generated production request is producible. In cases where the new production request is producible, the producible quantity calculation part  121  proceeds to the production request that is next in priority. Otherwise, the producible quantity calculation part  121  postpones the requested date of the newly-generated production request further, to the next date. 
         [0109]    The postponing method  1  repeats the above processing until all the production requests become producible. 
         [0110]      FIG. 12  is a schematic diagram for explaining a postponing method  2 . 
         [0111]    Here, the postponing method  2  generates a new production request such that its priority is highest among the production requests having the requested date next to the production request that has been judged to be non-producible, to produce the quantity which has been judged to be non-producible. If the new production request is judged to be non-producible at its requested date, a new production request is generated, having the highest priority among the production requests having the date next to that requested date. 
         [0112]    For example, with respect to the production request of priority “2” in the production request information shown in  FIG. 12A , if it is judged in the MRP processing that only “17” can be produced out of the requested quantity “20”, then the producible quantity calculation part  121  generates a new production request whose requested quantity is the quantity (here, “3”) that was originally judged to be non-producible, such that the priority of the new production request is highest among the production requests of the date (here, “2006/04/02”) next to the date of the original production request that has been judged to be non-producible, as in the production request information shown in  FIG. 12B . Further, the priorities of the production requests that have lower priorities than the priority of the newly-generated production request, are each lowered by one. 
         [0113]    With respect to the new production request information generated as described above, the producible quantity calculation part  121  performs the MRP processing again, to judge whether the newly-generated production request is producible. In cases where the newly-generated production request is non-producible, the producible quantity calculation part  121  repeatedly postpones the requested date by generating a new production request whose requested date is next to that date. 
         [0114]    The postponing method  2  repeats the above processing until all the production requests become producible. 
         [0115]    The postponing method is not limited to the above-described two methods. For example, it is possible that the method  1  is performed for a specific number of days and thereafter the method  2  is performed. 
         [0116]    Information that specifies the producible quantities calculated by the postponement according to the method  1  or  2  is tabulated as in the production plan table  115   a  shown in  FIG. 7  for each method, and stored in the production plan information storage area  115 . 
         [0117]    The display information generation part  122  generates a display image  116   a  as shown in  FIG. 8  from the production request information and the production plan table  115   a  (stored in the production plan information storage area  115 ) generated by the producible quantity calculation part  121  based on the production request information. The generated display image  116   a  is stored in the display information storage area  116 . 
         [0118]    The display information generation part  122  also performs processing of outputting the generated display image  116   a  to the output part  140  in response to a request from the operator of the calculation apparatus  100 , for example. Further, the display information generation part  122  also performs processing of sending the display image  116   a  through the sending/receiving part  150 , for example. 
         [0119]    The input part  130  is an input unit for inputting information. 
         [0120]    The output part  140  is an output unit for outputting information. 
         [0121]    The sending/receiving part  150  is a unit that sends and receives information through a network. 
         [0122]    The above-described calculation apparatus  100  can be implemented by a computer  170  as shown in  FIG. 13  (a schematic block diagram showing the computer  170 ). 
         [0123]    The computer  170  comprises a CPU  171 , a memory  172 , an external storage  173  such as an HDD or the like, a reader  175  for reading out information from a portable storage medium  174  such as a CD-ROM, a DVD-ROM or the like, an input unit  176  such as a keyboard and a mouse, an output unit  177  such as a display, and a communication unit  178  such as a Network Interface Card (NIC) for connecting to a communication network. 
         [0124]    For example, the storage part  110  can be implemented by the external storage  173 . The control part  120  can be implemented when a prescribed program stored in the external storage  173  is loaded to the memory  172  and executed by the CPU  171 . The sending/receiving part  150  can be implemented by the communication unit  178 . 
         [0125]    The prescribed program may be downloaded from the storage medium  174  though the reader  175  or from the network through the communication unit  178  into the external storage  173 , and then loaded into the memory  172  and executed by the CPU  171 . Alternatively, the prescribed program may be directly loaded from the network into the memory  172  though the communication unit  178 , to be executed by the CPU  171 . 
         [0126]    Processing performed by the calculation apparatus  100  of the above configuration will be described referring to the flowchart shown in  FIG. 14 . 
         [0127]    First, the calculation apparatus  100  acquires the production request information and the method information through the input part  130  (S 10 ). 
         [0128]    Next, the producible quantity calculation part  121  of the calculation apparatus  100  selects one postponing method from the postponing method information acquired in step S 10  (S 11 ). 
         [0129]    Next, the producible quantity calculation part  121  of the calculation apparatus  100  specifies one production request that has the highest priority among unprocessed production requests, from the production request information acquired in step S 10  (S 12 ). 
         [0130]    The producible quantity calculation part  121  of the calculation apparatus  100  performs the MRP processing on the production request specified in step S 12  (S 13 ). If the specified requested quantity of the product cannot be produced by the designated requested date (S 14 ), the processing flow goes to step S 15 . Otherwise, the processing flow goes to step S 16 . 
         [0131]    In step S 15 , the allocation for the production request judged to be non-producible is cancelled. The producible quantity calculation part  121  of the calculation apparatus  100  performs the postponement processing according to the postponing method selected in step S 11  (S 15 ). 
         [0132]    The producible quantity calculation part  121  of the control part  120  checks whether the processing of all the production requests in the production request information acquired in step S 10  has been finished or not (S 16 ). If the processing of all the production requests has not been finished, the processing flow returns to step S 12  to repeat the processing. 
         [0133]    If it is judged, in step S 16 , that the processing of all the production requests has been finished, then the producible quantity calculation part  121  of the control part  120  tabulates the results of the postponement processing into the production plan table  115   a , and stores the production plan table  115   a  in the production plan information storage area  115  (S 17 ). 
         [0134]    The producible quantity calculation part  121  of the control part  120  judges whether there is an unselected postponing method among the postponing methods specified by the postponing method information acquired in step S 10  (S 18 ). 
         [0135]    When it is judged, in step S 18 , that an unselected postponing method exists, then the processing flow returns to step S 11  to repeat the processing. On the other hand, when it is judged that no unselected postponing method exists, then the display information generation part  122  of the control part  120  generates a display image  116   a  from the production request information acquired in step S 10  and the production plan tables  115   a , and stores the generated display image  116   a  in the display information storage area  116  (S 19 ). 
         [0136]    The display image  116   a  stored in this way can be outputted to the output part  140  or sent to another apparatus through the sending/receiving part, so that the display image  116   a  can be seen, for example, through a display or the like. 
         [0137]    Since the display image  116   a  specifies production plans (producible quantities) according to a plurality of methods, it is possible to perform production according to a suitable production plan. 
         [0138]      FIG. 15  is a schematic diagram showing a calculation apparatus  200  as a second embodiment of the present invention. 
         [0139]    As shown in the figure, the calculation apparatus  200  comprises a storage part  210 , a control part, an input part  230 , an output part  140  and a sending/receiving part  150 . Since the storage part  210 , the control part  220  and the input part  230  are different from the ones in the first embodiment, these differences will be described below. 
         [0140]    The storage part  210  in the present embodiment comprises a part information storage area  111 , a lead time information storage area  112 , an initial stock information storage area  113 , an incoming-stock information storage area  114 , a production plan information storage area  215  and a display information storage area  216 . The part information storage area  111 , the lead time information storage area  112 , the initial stock information storage area  113  and the incoming-stock information storage area are the same as in the first embodiment, and their explanation is omitted here. 
         [0141]    The production plan information storage area  215  in the present embodiment also stores information that specifies a production plan generated by the below-described producible quantity calculation part  221 . In the first embodiment, a production plan table  115   a  is generated for each postponing method and stored in the production plan information storage area  215 . In the present embodiment, a production plan table  115   a  is generated for each piece of production request information and stored in the production plan information storage area  215 . 
         [0142]    Also in the present embodiment, the form of each production plan table  115   a  is similar to the one of the first embodiment, and its description is omitted. 
         [0143]    The display information storage area  216  in the present embodiment also stores display information generated by the below-described display information generation part  222 . Here, the display information displays, in a table, information that specifies the producible quantities calculated for each product according to pieces of production request information described below. 
         [0144]    For example, the display information storage area  216  in the present embodiment stores information that specifies a display image  216   a  as shown in  FIG. 16  (a schematic view showing the display image  216   a ). 
         [0145]    Similarly to the first embodiment, a display image  216   a  in the present embodiment has a product field  216   b , a type field  216   c  and a production plan field  216   d.    
         [0146]    The product field  216   b  stores identification information that identifies a product. Here, a name of a product is stored as the identification information. 
         [0147]    The type field  216   c  stores identification information that identifies a production request or a postponing method. In the present embodiment, a character string “Production Request n” is stored for the n-th piece of production request information (n is a natural number as an identification number for identifying a piece of production request information) among pieces of production request information. 
         [0148]    The production plan field  216   d  stores quantities producible by respective dates. Numbers in parentheses shown in the production plan field  216   d  indicate cumulative quantities. 
         [0149]    The control part  220  comprises a producible quantity calculation part  221  and a display information generation part  222 . 
         [0150]    The producible quantity calculation part  221  performs MRP processing or postponement processing on the basis of production request information acquired through the below-described input part  130  or the sending/receiving part  150 . 
         [0151]    In the present embodiment, MRP processing or postponement processing is performed for each piece of production request information. Particularly, in the present embodiment, when the priority order is changed with each piece of production request information, it is possible to refer to production plans for various kinds of priority order. 
         [0152]    Each method of the MRP processing or postponement processing is similar to the first embodiment, and its description is omitted. In the present embodiment, however, the postponement processing is performed according to one predetermined method. 
         [0153]    The display information generation part  222  generates a display image  216   a  as shown in  FIG. 16  from a production plan table  115   a  (stored in the production plan information storage area  215 ) generated by the producible quantity calculation part  121  on the basis of each piece of production request information. The generated display image  216   a  is stored in the display information storage area  216 . 
         [0154]    The display information generation part  222  also performs processing of outputting the generated display image  216   a  to the output part  140  in response to a request of the operator of the calculation apparatus  200  for example. Further, the display information generation part  222  also performs processing of sending the display image  216   a  through the sending/receiving part  150  for example. 
         [0155]    The input part  230  is an input unit for inputting information. In the first embodiment, the production request information and the method information are inputted. In the present embodiment, pieces of production request information are inputted. Particularly, when priority order of production requests is changed with each piece of production request, it is possible to refer to production plans for various kinds of priority order. 
         [0156]    Processing performed by the calculation apparatus  200  of the above-described configuration will be explained referring to the flowchart shown in  FIG. 17 . 
         [0157]    First, the calculation apparatus  200  acquires pieces of production request information through the input part  230  (S 20 ). 
         [0158]    Next, the producible quantity calculation part  221  of the calculation apparatus  200  selects one piece of unprocessed production information out of the pieces of production request information acquired in step S 20  (S 21 ). 
         [0159]    Next, the producible quantity calculation part  221  of the calculation apparatus  200  specifies one production request having the highest priority among unprocessed production requests from the production request information selected in step S 21  (S 22 ). 
         [0160]    The producible quantity calculation part  221  of the calculation apparatus  200  performs the MRP processing on the production request specified in step S 22  (S 23 ). If the designated requested quantity of the product cannot be produced by the designated requested date (S 24 ), the processing flow proceeds to step S 25 . If the production request is judged to be producible, the processing flow proceeds to step S 26 . 
         [0161]    In step S 25 , the allocation for the production request judged to be non-producible is cancelled. The producible quantity calculation part  221  of the calculation apparatus  200  performs the postponement processing according to the predetermined postponing method (S 25 ). 
         [0162]    In step S 26 , the producible quantity calculation part  221  of the control part  220  checks whether the processing of all the production requests in the production request information selected in step S 21  has been finished or not. If the processing of all the production requests has not been finished, the processing flow returns to step S 22  to repeat the processing. 
         [0163]    If it is judged, in step S 26 , that the processing of all the production requests has been finished, then the producible quantity calculation part  221  of the control part  220  tabulates the calculated production plan into the production plan table  115   a , and stores the production plan table  115   a  in the production plan information storage area  215  (S 27 ). 
         [0164]    The producible quantity calculation part  221  of the control part  220  judges whether there is an unselected piece among the pieces of production request information acquired in step S 20  (S 28 ). 
         [0165]    When it is judged, in step S 28 , that an unselected piece of production request information exists, then the processing flow returns to step S 21  to repeat the processing. On the other hand, when it is judged that no unselected piece of production request information exists, then the display information generation part  222  of the control part  220  generates a display image  216   a  from the production plan table  115   a , and stores the generated display image  216   a  in the display information storage area  216  (S 29 ). 
         [0166]    The display image  216   a  stored in this way can be outputted to the output part  140  or sent to another apparatus through the sending/receiving part  150 , so that the display image  216   a  can be seen, for example, through a display or the like. 
         [0167]    Since the display image  216   a  specifies production plans (producible quantities) according to pieces of production request information (priority order), it is possible to perform production according to a suitable production plan. 
         [0168]    In the second embodiment, particularly the priority order is changed with each piece of production request information, so that it is possible to perform production according to a suitable production plan. This mode, however, is not restrictive. For example, in the first embodiment, the priority order specified in the production request information can be changed randomly or according to a specific rule (for example, exchange of adjacent production requests) in order that various production plans can be referred to. 
         [0169]      FIG. 18  is a schematic diagram showing a calculation apparatus  300  as a third embodiment of the present invention. 
         [0170]    As shown in the figure, the calculation apparatus  300  comprises a storage part  310 , a control part  320 , an input part  330 , an output part  140  and a sending/receiving part  150 . In comparison with the first embodiment, since the storage part  310 , the control part  320  and the input part  330  are different, these differences will be described below. 
         [0171]    The storage part  310  of the present embodiment comprises a part information storage area  111 , a lead time information storage area  112 , an initial stock information storage area  113 , an incoming-stock information storage area  114 , a production plan information storage area  315  and a display information storage area  316 . The part information storage area  111 , the lead time information storage area  112 , the initial stock information storage area  113  and the incoming-stock information storage area  114  are similar to the first embodiment, and their description is omitted. 
         [0172]    The production plan information storage area  315  of the present embodiment also stores information that specifies a production plan generated by the below-described producible quantity calculation part  321 . In the first embodiment, a production plan table  115   a  is generated for each postponing method and stored in the production plan information storage area  215 . In the present embodiment, a production plan table  115   a  is generated for each method and for each piece of production request information, and stored in the production plan information storage area  315 . 
         [0173]    Also in the present embodiment, the form of each production plan table  115   a  is similar to the one of the first embodiment, and its description is omitted. 
         [0174]    The display information storage area  316  in the present embodiment also stores display information generated by the below-described display information generation part  322 . Here, the display information displays, in a table, information that specifies the producible quantities calculated for each product according to pieces of production request information described below. 
         [0175]    For example, the display information storage area  316  in the present embodiment stores information that specifies a display image  316   a  as shown in  FIG. 19  (a schematic view showing the display image  316   a ). 
         [0176]    The display image  316   a  in the present embodiment has a product field  316   b , a type field  316   c  and a production plan field  316   d , for each production request. Information stored in each field is similar to the first embodiment, and its description is omitted. 
         [0177]    The control part  320  comprises a producible quantity calculation part  321  and a display information generation part  322 . 
         [0178]    The producible quantity calculation part  321  performs MRP processing or postponement processing on the basis of pieces of production request information and method information acquired through the below-described input part  330  or sending/receiving part  150 . 
         [0179]    Each method of the MRP processing or postponement processing is similar to the first embodiment, and its description is omitted. In the present embodiment, however, postponement processing is performed with respect to pieces of production request information according to a plurality of postponing methods designated in the method information. 
         [0180]    The display information generation part  222  generates display images  316   a  as shown in  FIG. 19  from a production plan table  115   a  (stored in the production plan information storage area  315 ) generated by the producible quantity calculation part  121  on the basis of each piece of production request information, and stores the generated display images  316   a  in the display information storage area  316 . 
         [0181]    The display information generation part  222  also performs processing of outputting the display images  316   a  to the output part  140  in response to a request of the operator of the calculation apparatus  300  for example. Further, the display information generation part  222  also performs processing of sending the display images  316   a  through the sending/receiving part  150  for example. 
         [0182]    The input part  330  is an input unit for inputting information. In the present embodiment, pieces of production request information and method information are inputted. 
         [0183]    Processing performed by the calculation apparatus  300  of the above-described configuration will be explained referring to the flowchart shown in  FIG. 20 . 
         [0184]    First, the calculation apparatus  300  acquires pieces of production request information and method information through the input part  330  (S 30 ). 
         [0185]    Next, the producible quantity calculation part  321  of the calculation apparatus  300  selects one unselected postponing method among the postponing methods included in the method information acquired in step S 30  (S 31 ). 
         [0186]    Further, the producible quantity calculation part  321  of the calculation apparatus  300  selects one unprocessed piece of production request information among the pieces of production request information acquired in step S 30  (S 32 ). 
         [0187]    Next, the producible quantity calculation part  321  of the calculation apparatus  300  specifies one unprocessed production request having the highest priority among the unprocessed production requests on the basis of the piece of production request information selected in step S 32  (S 33 ). 
         [0188]    The producible quantity calculation part  321  of the calculation apparatus  300  performs the MRP processing on the production request specified in step S 33  (S 34 ). If the designated requested quantity of a product cannot be produced by the designated requested date (S 35 ), the processing flow proceeds to step S 36 . If the production request is judged to be producible, the processing flow proceeds to step S 37 . 
         [0189]    In step S 36 , the allocation for the production request judged to be non-producible is cancelled. The producible quantity calculation part  321  of the calculation apparatus  300  performs the postponement processing according to the postponing method selected in step S 31  (S 36 ). 
         [0190]    In step S 37 , the producible quantity calculation part  321  of the control part  320  checks whether the processing of all the production requests in the piece of production request information selected in step S 32  has been finished or not. If the processing of all the production requests has not been finished, the processing flow returns to step S 33  to repeat the processing. 
         [0191]    If it is judged, in step S 37 , that the processing of all the production requests has been finished, the processing flow proceeds to step S 38 . 
         [0192]    In step S 38 , the producible quantity calculation part  321  of the control part  320  checks whether the processing of all the pieces of production request information acquired in step S 30  has been finished or not. If the processing of all the pieces of production request information has not been finished, the processing flow returns to step S 32  to repeat the processing. 
         [0193]    If it is judged, in step S 38 , that the processing of all the pieces of production request information has been finished, then the processing flow proceeds to step S 39 . 
         [0194]    In step S 39 , the producible quantity calculation part  321  of the control part  320  tabulates the calculated production plans into the production plan tables  115   a , and stores the production plan tables  115   a  in the production plan information storage area  315 . 
         [0195]    The producible quantity calculation part  321  of the control part  320  judges whether there is an unselected method among the postponing methods included in the method information acquired in step S 20  (S 40 ). 
         [0196]    When it is judged, in step S 40 , that an unselected postponing method exists, then the processing flow returns to step S 31  to repeat the processing. On the other hand, when it is judged that no unselected postponing method exists, then the display information generation part  322  of the control part  320  generates the display images  316   a  from the production plan tables  115   a , and stores the generated display images  316   a  in the display information storage area  316  (S 41 ). 
         [0197]    The display images  316   a  stored in this way can be outputted to the output part  140  or sent to another apparatus through the sending/receiving part  150 , so that the display images  316   a  can be seen through a display or the like for example. 
         [0198]    Since the display images  316   a  specify production plans (producible quantities) according to pieces of production request information and a plurality of methods, it is possible to perform production according to a suitable production plan. 
         [0199]    Each of the calculation apparatuses  100 ,  200  and  300  of the above-described configurations can be used in a calculation system  400  shown in  FIG. 21  (a schematic block diagram showing the calculation system  400 ). 
         [0200]    The calculation system  400  comprises a calculation apparatus  100 - 300  and a client terminal  180 . The calculation apparatus  100 - 300  and the client terminal  180  can send and receive information to and from each other through a network  181 . 
         [0201]    In the calculation system of this configuration, the client terminal  180  can send production request information and method information to the calculation apparatus  100 - 300 . The calculation apparatus  100 - 300  can calculate producible quantities and return a generated display image to the client terminal  180 . 
         [0202]    The client terminal  180  also can be implemented by a computer  170  as shown in  FIG. 13 .