JP3633337B2 - How to create NC data for seating surface processing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for creating NC (numerical control) data for seating surface machining used to machine each of a plurality of seating surfaces of a mold by a CAM (computer-aided machining) system.
[0002]
[Prior art]
In general, a mold used for press working or the like has a large number of mold structures such as a guide post GP, a wear plate WP, and a cam follower guide CG as shown in the perspective view of FIG. Therefore, at the time of manufacturing the mold, for example, as shown in the perspective view of FIG. 7 only for the lower die holder of FIG. 6, a large number of flat seating surfaces SP for mounting these mold structures are provided. It is necessary to perform processing.
[0003]
As a conventional method for creating NC data in order to process such a seating surface with an NC machine tool constituting a CAM system, for example, one disclosed in Japanese Patent Application Laid-Open No. Sho 62-239206 is known. In the method, the operator interacts with the computer while looking at the 3D mold shape model separately created by the CAD (Computer Aided Design) system on the screen of the NC data creation computer that also constitutes the CAM system. A part program constituting NC data is created by inputting the approach position of the tool and the tool trajectory at the time of machining for each seating surface according to the procedure shown in the flowchart of FIG.
[0004]
In the procedure shown in FIG. 8, first, in Step 1, the tool diameter, the tool length, the seat surface to be processed by the part program currently being created, and the interference object (other seat surfaces other than the target seat surface such as other surrounding seat surfaces). In step 2, select the tool approach position (approach point) to the target seating surface and enter it into the NC data creation computer. Automatically check the interference between the tool shape model and the die shape model at the approach position and the object seating surface, determine the approach position based on the result of the interference check, and use it for NC data creation Input to the computer.
[0005]
For example, in the example shown in the plan view of FIG. 9A, the two upper and lower positions on the left side of the target seating surface SP are input as the approach positions of the tool indicated by the tool model T. Since the interfering object IM exists in the upper left of the surface SP, the computer determines that the upper input position is NG (interference), determines that only the lower input position is OK, and displays the determination result on the screen. Thus, the operator determines the input position below the approach position.
[0006]
Next, in step 3 in FIG. 8, the operator sets a tool trajectory for machining the seating surface to be machined, and the tool model and die shape on the tool trajectory are set in the NC data creation computer. An interference check with a model interference object is automatically performed, a tool path is determined based on the result of the interference check, and this is input to the NC data creation computer.
[0007]
For example, in the example shown in the plan view of FIG. 9B, the tool trajectory CP is such that cutting points (tool passing points) PP are sequentially input and the cutting points PP are traced in the order of input, as indicated by x in the figure. The computer checks whether or not there is interference with the interference object while the tool model T moves along the tool path CP.
[0008]
Then, in the above procedure, finally, in step 4, the operator visually checks whether or not the target seating surface is left uncut by the movement of the tool that follows the tool locus on the screen.
[0009]
[Problems to be solved by the invention]
By the way, in the conventional method, as described above, the approach position of the tool and the tool trajectory at the time of machining are input to each seating surface in an interactive manner with the computer. As shown in (a), a machining allowance portion RP is provided on each seating surface SP of the mold shape model, and each portion of the tool model T including the arbor and the shank has an appropriate non-zero value corresponding to the portion. The margin C is set, and the computer is instructed to determine that there is no interference when each part of the tool model T is between the margin C separation at the approach position with respect to the allowance portion RP and other portions. Checking is done. Further, when the seat surface is processed, as shown in FIG. 10B, the allowance portion RP is not provided only on the target seat surface, and the margin C is set to zero on the bottom and side surfaces of the blade portion of the tool model T, and the tool trajectory is set. At each of the above positions, interference is judged with a margin of zero for the bottom and side surfaces of the blade, and interference is judged with a margin C of an appropriate value other than zero for the other parts of the tool model T. The computer is instructed to check for interference.
[0010]
However, in the above conventional method, since there are a plurality of seating surfaces, there should be a seating surface that has already been processed in the routing and should not cause interference. Since the machining allowance portion RP is provided, there is a case where the computer performs an interference check with extra restrictions on the approach position and the tool path, and the automatic machining rate of the mold is unnecessarily reduced. is there. In addition, since the operator gives the above instructions to the computer for each seating surface, the manpower of the operator increases, and even if the margin allowance instruction is incorrect, the computer should not cause interference. Causes an interference check mistake such as determining that there is interference, which places extra constraints on the choice of approach position and tool trajectory by the operator, which also unnecessarily reduces the automatic machining rate of the mold. May end up.
[0011]
[Means for solving the problems and their functions and effects]
An object of the present invention is to provide a method of creating NC data that advantageously solves the above-described problems. The method of creating NC data for seating surface processing according to the present invention includes a plurality of molds using a CAM system. When creating NC data used for machining each of the seating surfaces, the order of the plurality of seating surfaces is determined in advance, and when determining the tool approach position and the tool trajectory for each target seating surface, The machining allowance portion is not set for the seat surface to be processed earlier than the target seat surface in the order, and the allowance portion is set only for the target seat surface and the seat surface to be machined after that. The system is characterized in that an interference check is performed by a computer for creating NC data of the system.
[0012]
According to such a method, since no allowance is set for the seating surface to be processed before the target seating surface in the routing, there is no interference when checking the interference with the tool approach position or tool path. Therefore, the NC data creation computer does not erroneously determine that interference will occur with respect to the seating surface to be processed earlier, so that the automatic machining rate of the mold can be improved.
[0013]
Furthermore , in the method for creating the NC data for machining the seating surface of the present invention, the margin of the tool is set in advance for interference check for the tool approach position and for interference check for the tool path, When the computer for NC data creation of the CAM system performs the interference check for the tool approach position and the interference check for the tool trajectory, the corresponding one of the two margins is automatically switched and used . According to such a method, there is no possibility that the computer erroneously determines that interference occurs due to an error in setting the margin allowance even though there is no actual interference, and therefore the automatic machining rate of the mold can be further improved. it can.
[0014]
In the method for creating the NC data for seating surface machining according to the present invention, among the plurality of types of tool trajectories that have been confirmed to cause no interference with the NC data creation computer of the CAM system when the tool trajectory is determined. Therefore, it is possible to select the one having the smallest number of break points, and in this way, the processing time can be shortened and the quality of the processed surface can be improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing a procedure for carrying out an embodiment of a method of creating NC data for seating surface processing according to the present invention. The method of this embodiment is used for creating NC data constituting a normal CAM system. It is implemented by modifying the computer operating program.
[0016]
That is, in the method of this embodiment, first, in step 1 in FIG. 1, the data of the three-dimensional mold shape model separately created by the CAD system is read and the attributes of each part of the mold shape model are examined. All the seating surfaces are extracted, and the routing is set for those seating surfaces. Among those seating surfaces, the current processing of the seating surfaces for which the tool path has not yet been registered in step 16 described later. If one bearing surface (target bearing surface) that is the target of the part program that is being created is searched and there is no remaining bearing surface that does not have a registered tool path, the following step 2 follows. 1 is terminated, but if there is still a bearing surface for which no tool path has been registered, the above-described set process is selected from the bearing surfaces for which the tool path has not been registered in step 2 above. One in order The loci surface proceeds to step 3 after selecting the.
[0017]
In Step 3, a tool table indicating a list of tools included in the NC machine tool constituting the CAM system is read from the storage area of the computer. In Step 4, a tool to be used suitable for processing the target seating surface is obtained. Choose a thicker and shorter one with priority. If there are no more tools that can be selected, data indicating that there is no tool for the target seating surface is registered in step 5, and then the process returns to step 1 to search for the next target seating surface. On the other hand, if there is a tool that can be selected as a tool to be used, the process proceeds to step 6 after selecting the tool as a tool to be used in step 5 above.
[0018]
In the method of this embodiment, a three-dimensional tool model is created in advance with the CAD system for each tool on the tool table, and as shown in FIG. 2A, for checking the interference at the approach position. An appropriate non-zero margin C corresponding to each part of the tool model T including the arbor, shank, and blade part is set, and as shown in FIG. For the interference check of the tool model T, the margin is set to zero for the bottom surface of the blade CT of the tool model T and the side surface of the blade CT other than the upper end, and the other parts of the tool model T are not the previous zero. An appropriate margin C is set and read by the computer.
[0019]
In step 6, as shown in FIG. 3A, from the position of the target seating surface SP separated from the corner portion excluding the recess by a distance corresponding to the tool radius, in the extending direction of the side of the target seating surface SP. As an approach, one approach position is selected from a plurality of approach positions (only the positions AP1 to AP4 are shown in the figure) that satisfy the condition, and in step 7 that follows, the operator surrounds the target seating surface SP. One or a plurality of mold-shaped parts that are supposed to cause interference with the tool on the approach position and the tool trajectory are input as interference objects (interference objects IM1 and IM2 in the illustrated example), and FIG. As shown in Fig. 5, the tool model T at the approach position selected above is applied to the tool model T of the tool selected previously by applying the allowance for interference check at the approach position. Performing a three-dimensional interference check the fine locus plane SP itself.
[0020]
In the interference check at this approach position, as shown in FIG. 4, for example, the working order is the seating surface SP1, the seating surface SP2, and the seating surface SP3, and the seating surface SP2 of these seating surfaces is currently selected. The seating surface SP1 as the interference object positioned before the seating surface SP2 in the routing is not provided with the machining allowance portion RP, and the seating surface SP2 that is the subject seating surface of the current processing. In addition, an allowance portion RP is provided on the seating surface SP3 as an interferer positioned later in the work order to perform an interference check.
[0021]
Then, as shown in the approach positions AP1 to AP3 in FIG. 3B, interference between the interference object (interference object IM1 or IM2 in the illustrated example) and the tool model T occurs at the selected approach position (less than the allowance from the tool model). If the interfering object is located at a distance of (5), the process returns to step 6 via step 8, and the next approach position is selected from the approach positions satisfying the above conditions. On the other hand, if there is no interference between the interfering object IM1 or IM2 and the tool model T at the selected approach position, the process proceeds to step 9 through step 8.
[0022]
In step 9, as shown in FIGS. 5 (a) and 5 (b), the tool path CP from the selected approach position is automatically created in a scanning line, for example, with the tool radius of the selected tool used as the pitch, In the subsequent step 10, it is confirmed that there is no uncut area by calculating the uncut area when the target seating surface is machined by moving the tool along the tool path CP. Applying a margin for interference check on the tool path to the tool model T of the tool, the tool model T on the tool path CP, the interference object, and the target seat surface on the entire tool path CP Check for interference with itself.
[0023]
In the interference check on the tool path, as in the interference check at the previous approach position, for example, when the seating surface SP2 is the current target seating surface, the interference positioned before the seating surface SP2 in the work order. The seating surface SP1 as an object is not provided with a machining allowance portion RP, but a seating surface SP2 which is a target seating surface of the current processing and a seating surface SP3 which is an interference object positioned later in the routing are taken into account. An interference check is performed by providing a part RP. However, with respect to the target seating surface, the area where the blade part of the tool model T exists at the current position where the interference check of the tool model T on the tool trajectory is performed and the position before that is already cut off. Therefore, the interference check is performed without providing the allowance portion RP. If interference occurs, the process returns to step 4 through step 12 to select the next tool to be used that is suitable for processing the target seating surface. On the other hand, if no interference occurs, the process proceeds to step 13 where the created tool path is provisionally registered.
[0024]
In the next step 14, it is determined whether or not there is no approach position for which the tool path is not temporarily registered among one or a plurality of approach positions that satisfy the condition in step 6. Returning to 6, one more approach position is selected from the remaining ones, and if there is no approach position for which the tool path is not temporarily registered, the process proceeds to step 15.
[0025]
In step 15, the number of breakage points of the tool path, that is, the cutting path, the direction of the tool path changes more than a predetermined angle before and after the number of cutting points in the temporarily registered tool path, and the tool must be decelerated (FIG. 5). In the example shown in FIG. 5, since the direction of the tool trajectory changes by 90 degrees at each cutting point PP, the tool trajectory having the smallest number of cutting points PP except for the approach point and the retract point is selected. Therefore, in the two types of tool trajectory CP for the same seating surface SP shown in FIGS. 5A and 5B, the tool trajectory shown in FIG. Since the tool trajectory CP shown in b) has four break points, the tool trajectory CP shown in FIG. 5B has fewer break points, so the tool trajectory CP shown in FIG. Will choose. Usually, the number of break points is smaller when the approach direction is set to the longitudinal direction of the seating surface.
[0026]
In the subsequent step 16, the tool path selected in step 15 is registered. And then retrieves the next target seat returns to step 1, the repetition of such processing, when the approach position and the tool path for all the seating surface except the seating surface tool is not causing no interference is determined, In step 2, the target seating surface disappears, and this process ends.
[0027]
Therefore, according to the method of this embodiment, the machining allowance portion is not set in the seating surface to be machined before the target seating surface in the routing, so that interference is checked during the interference check on the tool approach position and the tool path. Therefore, there is no possibility that the NC data creation computer erroneously determines the interference with the seating surface to be machined first, and the automatic machining rate of the mold can be improved.
[0028]
In addition, according to the method of this embodiment, the margin of the tool is set in advance for the interference check for the tool approach position and for the interference check for the tool trajectory. When performing an interference check and an interference check on the tool path, the corresponding one of the two allowances is automatically switched and used. Thus, it is possible to prevent the computer from erroneously determining that interference occurs, and therefore, the automatic machining rate of the mold can be further improved.
[0029]
Furthermore, according to the method of this embodiment, when determining the tool trajectory, it is possible to select a tool trajectory with the smallest number of breakpoints from a plurality of types of tool trajectories that have been confirmed to cause no interference with the computer. Can be shortened and the quality of the machined surface can be improved.
[0030]
Although the present invention has been described based on the illustrated example, the present invention is not limited to the above-described example. For example, the creation of NC data based on the method of the present invention is a computer other than the CAM system, for example, a computer constituting a CAD system. It is also possible to do this.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a procedure for carrying out an embodiment of a method for creating NC data for seating surface processing according to the present invention.
FIG. 2 is a longitudinal sectional view showing how to make allowances and allowances for interference checking in the method of the embodiment.
FIG. 3 is an explanatory diagram showing, in plan view, a method for determining a tool approach position in the method of the embodiment.
FIG. 4 is an explanatory view showing, in a perspective view, how to provide a margin for interference check by the method of the embodiment.
FIG. 5 is an explanatory diagram showing a method for determining a tool path in the method of the embodiment in a plan view.
FIG. 6 is a perspective view illustrating a lower mold of a mold.
7 is a perspective view showing only the lower die holder shown in FIG. 6. FIG.
FIG. 8 is a flowchart showing a conventional method of creating NC data.
FIG. 9 is an explanatory diagram showing an interference check method according to the conventional method.
FIG. 10 is an explanatory view showing, in a vertical cross-sectional view, how to make allowances and how to make allowances in the conventional interference check.
[Explanation of symbols]
AP, AP1 to AP4 Approach position C Margin CG Cam follower guide CP Tool locus CT Blade part GP Guide post IM Interference object PP Cutting point RP Cutting allowance SP, SP1 to SP3 Seat surface T Tool model WP Wear plate

Claims (2)

In creating NC data used for machining each of the plurality of seating surfaces of the mold by the CAM system,
The route of the plurality of bearing surfaces is determined in advance,
When determining the tool approach position and tool trajectory for each target seating surface, do not set a machining allowance for the seating surface to be processed before the target seating surface in the routing, Set the allowance part only on the seat surface to be processed later, and let the computer for NC data creation of the CAM system perform an interference check ,
Two types of tool margins are set in advance, one for checking the interference for the tool approach position and the other for checking the interference for the tool path.
Rukoto automatically is switched using those corresponding from among the two types of margin when interference check and causes the interference check for the tool path for the tool approach position to the NC data creation computer of the CAM system A method of creating NC data for seating surface processing characterized by the above. When determining the tool trajectory, the NC data creation computer of the CAM system is selected from a plurality of types of tool trajectories that have been confirmed to cause no interference and having the smallest number of break points. The method of creating NC data for seating surface processing according to claim 1.

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