Abstract:
An object of this invention is to enable to appropriately carry out deposition due to a design change of an object. This invention comprises the steps of: calculating a difference between three dimensional data representing a form of an object before a design change and three dimensional data representing a form of the object after the design change; and generating deposition data for a shortage portion in the form of the object before the design change by using the calculated difference data, when cutting the object to make the form after the design change. Thus, it is possible to correctly grasp information concerning the deposition necessary to machine the object to make the form after the design change, and to avoid waste of deposition material and cutting work after the deposition. Moreover, this invention may further comprise a step of calculating a region for one or a plurality of deposition layers based on an attribute of a deposition material. Because the maximum thickness of one deposition layer or the like differs according to the attribute of the deposition material, it is useful in the deposition process to obtain regional information for each layer when the deposition is carried out by putting the deposition layers on top of each other.

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    This invention relates to information processing technology for deposition in machining.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the machining of an object such as a metal mold, once a design change occurs after the metal mold was made, it is general that the deposition is carried out for shortage portions of the material in the metal mold, and, by using Computer Aided Design (CAD) data after the design change, the machining is carried out for the changed portions by a Numerical Control (NC) machine or the like. Incidentally, because the material used for the deposition in the metal mold machining have high hardness, compared with the machining the base material such as cast, it takes time of several times to machine the portion at which the deposition was carried out.  
           [0003]    On the other hand, when the deposition was carried out, because it was not accurately known how much amount of deposition should be carried out to what portions, the deposition with a lot of margin including a cutting allowance (also called cutting margin), that is, the deposition with too large margin was carried out. Therefore, the waste of the deposition material and machining time after the deposition occurred.  
         SUMMARY OF THE INVENTION  
         [0004]    Therefore, an object of this invention is to provide information processing technology for carrying out the appropriate deposition.  
           [0005]    An information processing method according to this invention comprises a first step of calculating a difference between three dimensional data representing a form of an object before a design change and three dimensional data representing a form of the object after the design change; and a second step of generating deposition data for a shortage portion in the form of the object before the design change by using the calculated difference data, when machining (or cutting) the object to make the form after the design change.  
           [0006]    Thus, it is possible to correctly grasp information concerning the deposition necessary to machine the object to make the form after the design change, and to avoid waste of the deposition material and machining work after the deposition.  
           [0007]    In addition, the aforementioned second step may comprise a step of calculating a deposition region including a cutting allowance calculated based on the difference data. Thus, it becomes possible to set an appropriate amount of cutting allowance, and to avoid waste of the deposition material and machining work after the deposition.  
           [0008]    Moreover, the aforementioned second step may comprise a layer region calculating step of calculating a region of one or a plurality of deposition layers based on an attribute of a deposition material. Because the maximum thickness of one deposition layer or the like differs according to the attribute of the deposition material, it is useful in the deposition process to obtain regional information for each layer when the deposition is carried out by putting the deposition layers on top of each other.  
           [0009]    Furthermore, in the aforementioned layer region calculating step, the region of one or a plurality of deposition layers may be calculated according to a deposition method in which the deposition layers are put on top of each other from a surface of the object before the design change in the normal direction.  
           [0010]    Moreover, in the aforementioned layer region calculating step, the region of one or a plurality of deposition layers may be calculated according to a deposition method in which the deposition layers are put on top of each other in parallel to a specific reference plane.  
           [0011]    In addition, this invention may further comprise a step of generating data of a deposition instruction diagram based on the deposition data. Thus, a person in charge of the deposition work can appropriately carry out the deposition work according to the deposition instruction diagram.  
           [0012]    Moreover, this invention may further comprise a step of generating data for an automatic deposition machine based on the deposition data. Thus, the automatic deposition machine can appropriately carry out appropriate deposition processing based on the data for the automatic deposition machine.  
           [0013]    Furthermore, the aforementioned second step may further comprise a step of calculating deposition path data for the region of the deposition layer according to a deposition method in which the deposition is carried out in parallel by a predetermined deposition width. Thus, it is possible to deposit the region of the deposition layer in a stripe manner.  
           [0014]    In addition, the aforementioned second step may further comprise a step of calculating deposition path data for the region of the deposition layer according to a deposition method in which the deposition is carried out so as to form rings with a predetermined width. Thus, it is possible to deposit the region of the deposition layer so as to draw rings.  
           [0015]    Incidentally, it is also possible to create a program for carrying out a method according to this invention, and the program is stored in a storage medium or a storage device, for example, a flexible disk, a CD-ROM, a magneto-optical disk, a semiconductor memory, or a hard disk. Besides, there is also a case where the program is distributed as digital signals through a network. Incidentally, data under processing are temporarily stored in a memory of the computer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a functional block diagram in an embodiment of this invention;  
         [0017]    [0017]FIG. 2 is a diagram showing a processing flow in the embodiment of this invention;  
         [0018]    [0018]FIGS. 3A and 3B are diagrams showing examples of forms represented by CAD data;  
         [0019]    [0019]FIGS. 4A and 4B are diagrams showing deposition types;  
         [0020]    [0020]FIG. 5 is a conceptual diagram of a deposition region;  
         [0021]    [0021]FIGS. 6A and 6B are conceptual diagrams showing deposition types;  
         [0022]    [0022]FIGS. 7A and 7B are diagrams showing examples of deposition instruction diagrams;  
         [0023]    [0023]FIG. 8 is a diagram showing a processing flow of difference calculation between CAD data;  
         [0024]    [0024]FIG. 9 is a conceptual diagram showing an offset processing in the normal direction;  
         [0025]    [0025]FIG. 10 is a conceptual diagram showing a shift processing in the Z-axis direction;  
         [0026]    [0026]FIG. 11 is a diagram showing a processing flow of deposition layer specification;  
         [0027]    [0027]FIG. 12 is a conceptual diagram showing deposition layers in a first deposition type; and  
         [0028]    [0028]FIG. 13 is a conceptual diagram showing deposition layers in a second deposition type. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    [0029]FIG. 1 shows a functional block diagram of a deposition data generation apparatus  100  according to one embodiment of this invention. The deposition data generation apparatus  100  is a computer such as a personal computer or workstation, and includes a central processing unit, memory, file storage, and the like (not shown in FIG. 1). Moreover, the deposition data generation apparatus  100  includes a CAD data difference calculator  102 , cutting allowance addition processor  104 , deposition data generator  106 , deposition instruction diagram generator  108 , and automatic deposition data generator  110 .  
         [0030]    In addition, the deposition data generation apparatus  100  is connected to a display device  112 , output device  114  such as a printer or plotter, input device (not shown), CAD data storage  120 , maximum deposition amount data storage  122 , deposition type data storage  124 , deposition type data storage  126 , and automatic deposition data storage  128 . Incidentally, the CAD data storage  120  is managed by a CAD system (not shown) or the like, and is connected via a network such as a Local Area Network (LAN) with the deposition data generation apparatus  100 . Furthermore, the automatic deposition data storage  128  is also connected with an automatic deposition machine  130 .  
         [0031]    CAD data before and after the design change is stored in the CAD data storage  120 , and it is referenced by the CAD data difference calculator  102  in the deposition data generation apparatus  100 . The processing result of the CAD data difference calculator  102  is output to the cutting allowance addition processor  104 , and the processing result of the cutting allowance addition processor  104  is output to the deposition data generator  106 .  
         [0032]    Data concerning patterns to put deposition layers on top of each other is stored in the deposition type data storage  124 , and data concerning deposition methods for each deposition layer is stored in the deposition type data storage  126 . The details will be described later. And, data stored in the deposition type data storage  124  is referenced by the CAD data difference calculator  102  and deposition data generator  106 . In addition, data stored in the maximum deposition amount data storage  122  and data stored in the deposition type data storage are referenced by the deposition data generator  106 .  
         [0033]    The processing result of the deposition data generator  106  is output to the deposition instruction diagram generator  108  and automatic deposition data generator  110 . The processing result of the deposition instruction diagram generator  108  is transmitted to the output device  114 , and the processing result of the automatic deposition data generator  110  is stored in the automatic deposition data storage  128 . Then, data stored in the automatic deposition data storage  128  is referenced by the automatic deposition machine  130 . Incidentally, data used or generated in each processing step by the deposition data generation apparatus  100  may be properly displayed on the display device  112 .  
         [0034]    Next, a processing flow of the deposition data generation apparatus  100  shown in FIG. 1 will be explained by using FIG. 2. For example, in the metal mold machining, once the design change occurs after the metal mold has been made, the deposition data generation apparatus  100  accepts inputs of data (for example, codes) concerning the deposition material for the deposition due to the design change, deposition type, and automatic deposition type via the input device (not shown) or the like, and stores them into the storage device (step S 1 ).  
         [0035]    Then, the deposition data generation apparatus  100  obtains CAD data before the design change for the metal mold from the CAD data storage  120 , and stores it into the storage device (step S 3 ). In addition, the deposition data generation apparatus  100  obtains CAD data after the design change for the metal mold from the CAD data storage  120 , and stores it into the storage device (step S 5 ). It is also possible to designate the CAD data before and after the design change by using the input device or the like.  
         [0036]    [0036]FIGS. 3A and 3B show cross section examples of forms represented by the CAD data. In the figures used in the subsequent explanation, two-dimensional examples (e.g. cross sections) are shown to simplify the explanation. However, three-dimensional data is actually used to carry out the same processings.  
         [0037]    [0037]FIG. 3A shows an example of the CAD data before the design change. In this example, a form is shown in which there is the highest portion like a hill on the slightly left side from the center of this figure, and the height is lowered stepwise toward the right side.  
         [0038]    Moreover, FIG. 3B shows an example of the CAD data after the design change. In this example, a form is shown in which there is the highest portion like a hill on the slightly right side from the center of this figure. Though the details will be explained later, compared with FIGS. 3A and 3B, it can be understood that the deposition should be carried out for a portion in which the contour of the form shown in FIG. 3B, which is represented by the geometric data after the design change, is higher than that shown in FIG. 3A, that is, a portion on the right side from the center of the figure.  
         [0039]    Returning to the processing flow in FIG. 2, the CAD data difference calculator  102  of the deposition data generation apparatus  100  retrieves the deposition type data storage  124  by using a code of the deposition type, which is accepted at the step S 1 , and specifies data of the deposition type (step S 7 ). In this embodiment, there are two deposition types, and either of the deposition types is specified.  
         [0040]    [0040]FIGS. 4A and 4B show conceptual figures to explain the deposition types, which can be designated in this embodiment. FIGS. 4A and 4B show a cross section of a deposition region. In both figures, a portion surrounded by a dotted line representing a surface of the metal mold before the design change and a solid line representing a surface of the metal mold after the design change is a region in which the deposition is carried out. In addition, boundaries between the deposition layers are indicated by chain lines.  
         [0041]    [0041]FIG. 4A shows a first deposition layer  41 , second deposition layer  42 , third deposition layer  43 , and fourth deposition layer  44 . In the actual deposition work, the deposition is carried out from the first deposition layer  41  so as to put layers on top of each other. That is, FIG. 4A shows an example of the first deposition type in which the deposition layers are put on top of each other in the normal direction from the surface of the metal mold before the design change.  
         [0042]    [0042]FIG. 4B shows a first deposition layer  45 , second deposition layer  46 , third deposition layer  47 , fourth deposition layer  48 , and fifth deposition layer  49 . In the actual deposition work, the deposition is carried out from the first layer  45  so as to put layers on top of each other. That is, FIG. 4B shows an example of the second deposition type in which the deposition layers are put on top of each other horizontally.  
         [0043]    Thus, even when the deposition is carried out for the same region, attributes such as a shape and size of each deposition layer differ according to the deposition type.  
         [0044]    Returning to the explanation of FIG. 2, the CAD data difference calculator  102  calculates a difference between the CAD data after the design change and the CAD data before the design change based on the deposition type data (step S 9 ). Because a difference calculation method is selected based on the deposition type, the deposition type data is used in the difference calculation. Though the details of the difference calculation method will be explained later, a difference model of the CAD data is specified as the calculation result.  
         [0045]    Next, the cutting allowance addition processor  104  adds data for the cutting allowance (also called cutting margin) to the difference model, which is the processing result of the CAD data difference calculator  102 , to generate data for the deposition region (step S 11 ).  
         [0046]    [0046]FIG. 5 shows a conceptual figure of the deposition region. FIG. 5 is a figure (i.e. cross section) that shows a state overlapping the forms represented by the CAD data before and after the design change (See FIGS. 3A and 3B). In FIG. 5, the surface of the metal mold before the design change is indicated by a dotted line  52 , the surface of the metal mold after the design change is indicated by a solid line  50 , and the difference model is indicated by a portion surrounded by the solid line  50  and dotted line  52  (i.e. a region indicated by chain lines).  
         [0047]    In addition, a portion surrounded by a part of the surface of the difference model, which is indicated by the solid line  50 , and a two-dot chain line  54 , which is placed apart from the surface of the difference model by a predetermined width in the normal direction, represents the cutting allowance. That is, the cutting allowance is set by offsetting the difference model outside by a predetermined distance along the normal direction of the surface of the difference model. Then, the portion surrounded by the chain double-dashed line  54  and dotted line  52  represents the deposition region including the cutting allowance. Thus, by adding the cutting allowance to the difference model, the deposition region is specified.  
         [0048]    Returning to the processing flow of FIG. 2, the deposition data generator  106  carries out a processing to specify the deposition layers by using the data of the deposition region (step S 13 ). Though the details of the processing to specify the deposition layers will be later, as the processing result, data concerning each deposition layer is specified.  
         [0049]    Next, the deposition data generator  106  judges whether or not the deposition is carried out automatically (step S 15 ). Data used in this judgment may be preset or accepted at the step S 1  as the input data.  
         [0050]    If it is judged that it is automatically carried out (step S 15 : Yes route), the deposition data generator  106  outputs the data concerning each deposition layer to the automatic deposition data generator  110 . Then, the automatic deposition data generator  110  retrieves the deposition type data storage  126  by using a code of the deposition type, which was accepted at the step S 1 , and specify the data of the deposition type (step S 17 ). In this embodiment, there are two deposition types, and either of the deposition types is specified.  
         [0051]    [0051]FIGS. 6A and 6B show conceptual figures of the deposition types, which can be designated in this embodiment. FIGS. 6A and 6B show a top view of one deposition layer. FIG. 6A shows an area  60  of one deposition layer, and deposition lines  62  represented by dotted lines. In addition, the boundaries between deposition stripes are represented by solid lines, and the distance between two adjacent solid lines means a deposition width. One or plural deposition lines  62  are set at predetermined deposition intervals (i.e. deposition pitch) in parallel, and in the actual deposition work, the deposition is carried out so as to put the center of the deposition width (i.e. interval) on the deposition line  62 . That is, FIG. 6A shows an example of a first deposition type in which the deposition is carried out for the area  60  of one deposition layer in a stripe manner.  
         [0052]    [0052]FIG. 6B shows an area  64  of one deposition layer, and deposition lines  66  represented by dotted lines. Boundaries between deposition rings are represented by solid lines and are set from the outside of the area  64  of one deposition layer, which is represented by the chain double-dashed line, toward the inside in a manner of rings having the same intervals. The distance between two adjacent boundaries means the deposition width. Moreover, the deposition lines  66  are set between the deposition boundaries in a ring manner. In the actual deposition work, the deposition is carried out so as to put the center of the deposition width on the deposition line  66 . That is, FIG. 6B shows an example of a second deposition type in which the deposition is carried out for the area  64  of one deposition layer so as to draw rings having a predetermined width (i.e. deposition pitch or interval).  
         [0053]    Thus, even when the deposition is carried out to the same area, either of different deposition types can be selected to carry out the deposition. Incidentally, according to the automatic deposition machine  130  to be used, the deposition type may be determined.  
         [0054]    Returning to the processing flow of FIG. 2, the automatic deposition data generator  110  generates data to control the automatic deposition machine  130 , such as data concerning the deposition lines (i.e. path), which includes position data, by using the data concerning each deposition layer and data of the automatic deposition type, and stores it into the automatic deposition data storage  128  (step S 19 ). The automatic deposition machine  130  carries out a deposition processing using the data stored in the automatic deposition data storage  128 .  
         [0055]    On the other hand, at the step S 15 , if it is judged that it is not the automatic deposition (step S 15 : No route), the deposition data generator  106  outputs the data concerning each deposition layer to the deposition instruction diagram generator  108 . The deposition instruction diagram generator  108  generates data for the deposition instruction diagram by using the data concerning each deposition layer to the output device  114 . Then, the output device  114  outputs the deposition instruction diagram on a paper, for example, by using the data for the deposition instruction diagram, which was received from the deposition instruction diagram generator  108  (step S 21 ). Incidentally, the deposition instruction diagram may be displayed on the display device  112 .  
         [0056]    [0056]FIGS. 7A and 7B show examples of the deposition instruction diagrams. FIG. 7A shows a first deposition layer  71 , second deposition layer  72 , third deposition layer  73 , and fourth deposition layer  74 . In the actual deposition work, the deposition is carried out from the first deposition layer  71  so as to put layers on top of each other in turn. That is, FIG. 7A shows an example of the deposition instruction diagram corresponding to the first deposition type (See FIG. 4A) in which the deposition layers are put on top of each other from the surface of the metal mold before the design change in the normal direction.  
         [0057]    [0057]FIG. 7B shows a first deposition layer  75 , second deposition layer  76 , third deposition layer  77 , fourth deposition layer  78 , and fifth deposition layer  79 . In the actual deposition work, the deposition is carried out from the first deposition layer  75  so as to put layers on top of each other in turn. That is, FIG. 7B shows an example of the deposition instruction diagram corresponding to the second deposition type (See FIG. 4B) in which the deposition layers are put on top of each other horizontally.  
         [0058]    Thus, even when the deposition is carried out for the same region, the deposition instruction diagram that enables a user to easily and appropriately grasp the deposition region according to the deposition type is output. Then, a person in charge of the deposition work carries out the deposition work according to the deposition instruction diagram.  
         [0059]    According to this embodiment, it becomes possible to appropriately perform the deposition work caused by the design change of the object such as the metal mold.  
         [0060]    Next, a processing to calculate the difference between the CAD data at the step S 9  in FIG. 2 will be explained by using FIG. 8. First, the CAD data difference calculator  102  judges whether the deposition type indicated by the data (e.g. code) of the deposition type obtained at the step S 1  of FIG. 2 represents the first deposition type (step S 31  in FIG. 8). If it is judged that it represents the first deposition type (step S 31 : Yes route), the CAD data difference calculator  102  shifts (so called “offsets”) the surface of the form represented by the CAD data before or after the design change, in the normal direction of the surface of the form represented by the reference CAD data, by a predetermined distance, in a scene in which the forms represented by the CAD data before and after the design change are superposed (step S 33 ).  
         [0061]    [0061]FIG. 9 shows a conceptual figure of the offsetting in the normal direction. FIG. 9 shows a figure (i.e. cross section) that shows a state overlapping the forms represented by the CAD data before and after the design change. In an example of FIG. 9, the surface of the metal mold before the design change is indicated by a solid line  90 , the surface of the metal mold after the design change is indicated by a dotted line  92 , and a portion surrounded by the solid line  90  and the dotted line  92  represents a difference due to the design change. Incidentally, a portion in which the solid line  90  is higher than the dotted line  92  is a subject of the cutting, and is not a subject of a processing for obtaining the difference model for the deposition in this embodiment.  
         [0062]    Moreover, in the example of FIG. 9, the CAD data before the design change is reference CAD data, and the CAD data after the design change is counterpart CAD data. Therefore, a chain line  94  indicates a form in which the form represented by the CAD data before the design change, which is shown by the solid line  90 , is offset in the normal direction of the surface of the form by a predetermined width. The forms after the offsetting, which are indicated by the chain lines  94 , are generated from the lower level toward the upper level of this figure in turn in this embodiment. Incidentally, the offset width is set to a value, which is the same as or smaller than an allowable error in the form.  
         [0063]    Returning to the processing flow of FIG. 8, for example, in a case where the CAD data before the design change is reference CAD data, the CAD data difference calculator  102  judges whether a portion exists in which the surface of the form after the design change, which is represented by the counterpart CAD data, is higher than the surface of the form after the offsetting, that is, whether a cross point between the chain line  94  representing the surface of the form after the offsetting in the example of FIG. 9 and the dotted line  92  representing the surface of the form after the design change exists (step S 35 ). If it is judged that the cross point exists, the CAD data difference calculator  102  temporarily stores the cross point and the form data after the offsetting into the storage device (step S 37 ). Then, the processing returns to the step S 33 , and the CAD data difference calculator  102  further offsets the surface of the form represented by the reference CAD data along the normal direction.  
         [0064]    Thus, the processing at the step S 33  and S 37  is repeated until it is judged that any cross point does not exist at the step S 35 . Then, if it is judged that any cross point does not exist at the step S 35  (step S 35 : Yes route), the CAD data difference calculator  102  generates the difference model data by using the intersections and the form data after the shifting, which are stored in the storage device at the step S 37  (step S 45 ).  
         [0065]    On the other hand, if it is judged at the step S 31  that it does not represent the first deposition type (step S 31 : No route), the CAD data difference calculator  102  shifts the surface of the form represented by the CAD data before or after the design change, which is treated as reference CAD data, in the Z-axis direction (i.e. vertically upper direction against the reference plane, which is a horizontal plane, for example), by a predetermined distance in a scene in which the forms represented by the CAD data before and after the design change are superposed (step S 39 ).  
         [0066]    [0066]FIG. 10 shows a conceptual figure of the shifting in the Z-axis direction. FIG. 10 shows a figure (i.e. cross section) that represents a state overlapping the forms represented by the CAD data before and after the design change. In an example of FIG. 10, the surface of the metal mold before the design change is indicated by a solid line  10 , the surface of the metal mold after the design change is indicated by a dotted line  12 , and a portion surrounded by the solid line  10  and dotted line  12  represents a difference due to the design change. Incidentally, a portion in which the solid line  10  is higher than the dotted line  12  is a subject of the cutting, and is not a subject of a processing for obtaining the difference model for the deposition in this embodiment.  
         [0067]    Moreover, in the example of FIG. 10, the CAD data before the design change is reference CAD data, and the CAD data after the design change is counterpart CAD data. Therefore, a dashed line  14  shows a form in which the surface of the form represented by the CAD data before the design change, which is indicated by the solid line  10 , is shifted in the Z-axis direction by a predetermined width. The forms after the shifting, which are indicated by the chain lines  14 , are generated from the lower level toward the upper level of this figure in turn in this embodiment. Incidentally, the shifting width is set to a value, which is the same as or smaller than an allowable error in the form.  
         [0068]    Returning to the processing flow of FIG. 8, for example, in a case where the CAD data before the design change is reference CAD data, the CAD data difference calculator  102  judges whether a portion exists in which the surface of the form after the design change, which is represented by the counterpart CAD data, is higher than the surface of the reference form after the shifting, that is, whether an intersection between the chain line  94  representing the form after the shifting in the example of FIG.  10  and the dotted line  92  representing the form after the design change exists (step S 41 ). If it is judged that the intersection exists (step S 41 : No route), the CAD data difference calculator  102  temporarily stores the intersection and the form data after the shifting into the storage device (step S 43 ). Then, the processing returns to the step S 39 , and the CAD data difference calculator  102  further shifts the surface of the form represented by the reference CAD data along the Z-axis direction.  
         [0069]    Thus, the processing at the step S 39  and S 43  is repeated until it is judged that any intersection does not exist at the step S 41 . Then, if it is judged at the step S 41  that any cross point does not exist (step S 41 : Yes route), the CAD data difference calculator  102  generates the difference model data by using the cross points and the form data after the shifting, which are stored in the storage device at the step S 43  (step S 45 ).  
         [0070]    As described above, for example, according to either of the two methods, the calculation processing of the difference between the CAD data is carried out. Incidentally, the generated difference model data is output to the cutting allowance addition processor  104  as the processing result of the CAD data difference calculator  102 .  
         [0071]    Next, a processing to specify the deposition layer at the step S 13  of FIG. 2 will be explained using FIG. 11. First, the deposition data generator  106  retrieves the maximum deposition amount data storage  122  by using the material data obtained at the step S 1  of FIG. 2, and specifies the maximum deposition amount of one deposition in a case where the designated deposition material is used (step S 51  in FIG. 11).  
         [0072]    Then, the deposition data generator  106  judges whether data (e.g. a code) of the deposition type obtained at the step S 1  of FIG. 2 represents the first deposition type (step S 53 ). If it is judged that it represents the first deposition type (step S 53 : Yes route), the deposition data generator  106  generates data concerning the area of the deposition layer, which has a form in which the difference model with the cutting allowance is sliced by the maximum deposition amount (i.e. thickness) specified at the step S 51  (step S 55 ). Here, since it represents the first deposition type, the difference model (See FIG. 9) that was generated by the offsetting in the normal direction, which was explained at the step S 33  of FIG. 8, and to which the cutting allowance is added, is used as a form to be sliced. Then, by using a method for slicing the difference model with the cutting allowance by a thickness based on the amount of one deposition according to the forms offset in the normal direction as explained at the step S 33  of FIG. 8, it is divided into one or plural deposition layers.  
         [0073]    Then, the deposition data generator  106  maps area data of each deposition layer to the CAD data before the design change, and specifies position data of the area to be actually deposited and the like (step S 57 ).  
         [0074]    [0074]FIG. 12 shows a conceptual figure of the deposition layers in the first deposition type. FIG. 12 is a figure (i.e. cross section) that shows a state overlaying the form represented by the CAD data before the design change and the forms represented by the area data of the deposition layers. The surface of the metal mold before the design change is indicated by a chain double-dashed line  1210 , and a portion surrounded by a solid line  1200  represents the difference mode with the cutting allowance (see FIG. 9). Then, boundaries between layers generated by slicing the difference model, that is, sections are indicated by chain lines  1220 . Thus, in case of the first deposition type, the slicing processing is carried out by using the data of the offsetting in the normal direction, which is included in the difference model.  
         [0075]    Returning to the processing flow in FIG. 11, the deposition data generator  106  temporarily stores the data concerning each deposition layer into the storage device (step S 63 ).  
         [0076]    On the other hand, if it is judged at the step S 53  that it does not represent the first deposition type, the deposition data generator  106  maps the difference model with the cutting allowance to the CAD data after the design change, and specifies position data of the area to be deposited and the like (step S 59 ). Here, since it represents the second deposition type, the difference model (See FIG. 10) that is generated by the shifting in the Z-axis direction, and to which the cutting allowance is added, is used as a form to be mapped.  
         [0077]    Then, the deposition data generator  106  generates data concerning the area of the deposition layer, which has a form sliced by the maximum deposition amount (i.e. thickness) specified at the step S 51  (step S 61 ). That is, by using a method for slicing the difference model with the cutting allowance by a thickness based on the amount of one deposition in parallel to the reference plane, which is a horizontal plane, for example, it is divided into one or plural deposition layers.  
         [0078]    [0078]FIG. 13 shows a conceptual figure of the deposition layers in the second deposition type. FIG. 13 is a figure (i.e. cross section) that shows a state superposing the form represented by the CAD data after the difference model and the difference model (See FIG. 10) generated by the shifting in the Z-axis direction. The surface of the metal mold after the design change is indicated by a chain double-dashed line  1310 , and the difference model with the cutting allowance is represented by a portion surrounded by the solid line  1300 . Then, boundaries between layers generated by slicing the difference model, that is, sections are indicated by dashed lines  1320 . Thus, in case of the second deposition type, the slicing processing is carried out in parallel to the reference plane such as the horizontal plane.  
         [0079]    The difference model generated by the shifting in the Z-axis direction is used, since the necessary computational volume is smaller, compared with a case in which the difference model is generated by the offsetting in the normal direction. Therefore, the difference model generated by the offsetting in the normal direction may be sliced in parallel to the reference plane such as the horizontal plane.  
         [0080]    Returning to the processing flow of FIG. 11, the deposition data generator  106  temporarily stores the data concerning each deposition layer (step S 63 ).  
         [0081]    Thus, the data concerning each deposition layer is specified. Incidentally, the specified data concerning each deposition layer is output to the deposition instruction diagram generator  108  or automatic deposition data generator  110  as the processing result of the deposition data generator  106 .  
         [0082]    Though one embodiment of this invention was explained, this invention is not limited to this embodiment. For example, the functional block diagram of the deposition data generation apparatus  100  shown in FIG. 1 is one example, and the program modules corresponding to the functional blocks may not be created. In addition, the deposition data generation apparatus  100  is configured by not only one computer, but also a plurality of computers. Similarly, a plurality of display devices  112 , output devices  114  and automatic deposition machines  130  may exist.  
         [0083]    Incidentally, in the aforementioned embodiment, an example of the metal mold machining was explained, but the application of this invention is not limited to the metal mold, and the technology of this invention is applicable to the machining of other objects for which the deposition due to the design change may occur.  
         [0084]    Although the present invention has been described with respect to a specific preferred embodiment thereof, various change and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes and modifications as fall within the scope of the appended claims.