JP2005050255A - Working data preparing method and program, and recording medium with program recorded - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently execute highly precise working by applying this working data preparing method to metallic mold working or the like adopting, for example, a CAM (Computer Aided Manufacturing) method. <P>SOLUTION: This working data preparing method, working data preparing program, and recording medium for recording the working data preparing program are configured to execute a cutting working by fixing the engage angle of a tool. Thus, it is possible to almost fix cutting resistance even when fixing the feeding speed of the tool. Therefore, it is possible to smooth finish surface roughness, and to efficiently execute highly precise working. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a machining data creation method, a machining data creation program, and a recording medium on which the machining data creation program is recorded, and can be applied to, for example, die machining using a CAM (Computer Aided Manufacturing) technique. According to the present invention, by performing cutting with a constant engagement angle of the tool, the cutting resistance can be made substantially constant even if the feed speed of the tool is constant, and the finished surface roughness can be made smooth. It is possible to perform high-precision machining efficiently.

  Conventionally, in die machining, tool locus data is created by CAM to shorten and simplify the die creation process.

  In other words, the CAM in this mold processing is processed by a computer by receiving shape data created by CAD (Computer Aided Design) and by using shape data input based on a mold drawing or the like. Know the shape of the mold. Further, the CAM generates data for rough machining, finishing machining, and the like in the computer according to the shape, and supplies the generated data to the NC machine tool.

  When creating this data, the CAM computer sets cutting conditions according to the operator's designation in an interactive format, etc., and this makes it possible to set the gold according to the appropriate cutting conditions according to the materials, tools, and NC machine tools used for cutting. The mold can be processed.

  In relation to such a method for creating machining data, conventionally, various methods for creating a tool path have been proposed. For example, in Japanese Patent Application Laid-Open No. 7-20920, a shape to be machined is proposed. A method has been proposed in which data offset by the tool radius is created and the tool is moved along this data. According to this method, by moving the tool along the offset data, it is possible to easily perform die processing according to the tool to be used.

  By the way, in the die machining, there is one in which a tool trajectory is generated so as to draw a contour line along the z-axis, and the machining target is contoured by moving the tool along the tool trajectory. In this case, it is considered that by changing the feed rate of the tool according to the machining shape, a desired machining surface accuracy can be obtained with a constant cutting resistance as a load applied to the tool.

However, when the feed rate of the tool is changed according to the machining shape, there is a problem that the machining efficiency is lowered.
Japanese Patent Laid-Open No. 7-20920

  The present invention has been made in consideration of the above points, and it is possible to make the cutting resistance substantially constant even when the feed rate of the tool is constant, and a machining data creation method capable of efficiently performing high-precision machining. The present invention intends to propose a machining data creation program and a recording medium on which the machining data creation program is recorded.

  In order to solve such a problem, in the invention of claim 1, in the machining data creation method for creating the tool trajectory data of the cutting work that cuts the work object sequentially step by step and finally forms the target shape, at least the final A step of creating a previous tool trajectory so that the engagement angle of the tool moving along the tool trajectory related to the finishing is less than or equal to a predetermined value.

  According to a second aspect of the present invention, in the configuration of the first aspect, the step of creating the tool trajectory corrects a tool trajectory obtained by offsetting the tool trajectory related to the final finishing by a predetermined amount.

  According to a third aspect of the present invention, in the configuration of the first aspect, in the step of creating the tool path, the engagement angle is set while moving each point on the tool path in the previous stage by a predetermined amount in the normal direction. A correction position that is less than or equal to a predetermined value is obtained.

  According to a fourth aspect of the present invention, there is provided a program for causing a computer to execute a predetermined processing procedure, wherein the program sequentially cuts a machining target in a stepwise manner and finally forms a target shape. A machining data creation program for creating a tool trajectory in a previous stage so that an engagement angle of a tool moving along at least a tool trajectory related to final finishing is a predetermined value or less. To do.

  In the invention of claim 5, the machining data creation program according to claim 4 is recorded by applying the machining data creation program to the recording medium.

  According to the configuration of claim 1, the tool is applied to the machining data creation method, and the engagement angle with respect to the tool is always constant. The cutting force applied to the tool can be made constant. By making the cutting resistance constant in this way, a uniform machined surface can be obtained, and an error with respect to the machining target value can be reduced. Thus, it is possible to perform machining with high accuracy while keeping the feed rate of the tool constant, thereby increasing machining efficiency.

  According to the configuration of claim 2, in the configuration of claim 1, the tool trajectory obtained by offsetting the tool trajectory related to the final finishing by a predetermined amount is corrected to thereby increase the engagement angle of the tool at the time of final finishing. Thus, it is possible to perform machining with high accuracy while keeping the feed rate of the tool constant in the final finishing.

  According to the configuration of claim 3, in the configuration of claim 1, a correction position where the engagement angle becomes a predetermined value or less is obtained while moving each point on the tool trajectory in the previous stage by a predetermined amount in the normal direction. Thus, an optimum correction value can be obtained with a simple process.

  According to the fourth aspect of the present invention, the cutting resistance can be made substantially constant even when the feed rate of the tool is made constant by being applied to the machining data creation program, and highly accurate machining can be performed efficiently. A machining data creation program can be obtained.

  According to the configuration of claim 5, by applying the machining data creation program to the recording medium and recording the machining data creation program of claim 4, high-precision machining can be efficiently performed compared to the conventional case. A recording medium on which a machining data creation program that can be performed is recorded can be obtained.

  According to the present invention, by performing the cutting process with a constant engagement angle of the tool, it is possible to make the cutting resistance substantially constant even if the feed speed of the tool is constant, and to perform highly accurate machining efficiently. Can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

(1) Configuration of Embodiment FIG. 2 is a block diagram showing a CAM system according to an embodiment of the present invention. This CAM system 1 is an arithmetic processing unit based on shape data D1 created by CAD via online, floppy (registered trademark) disk, or by shape data D1 input based on a mold drawing or the like. The machining data creation device 2 creates machining data D3 for mold machining.

  Here, the machining data D3 is formed by NC data, and the machining data creation device 2 supplies the machining data D3 to the NC machine tool online or by a floppy disk.

  In the machining data creation device 2, an internal central processing unit executes a processing program related to machining data creation processing provided by prior installation, so that a message or the like can be sent via the display device 3 as necessary. In addition to the display, the operator inputs the work size, material, tool used (end mill, etc.), etc. via the input device 4 such as a keyboard, mouse, etc., thereby accepting the machining conditions interactively. Furthermore, a tool trajectory is generated from the shape data D1 so that the tool engagement angle is constant according to the accepted machining conditions. In this processing program, it may be provided by a network such as a recording medium or the Internet in place of such provisional installation. Examples of such a recording medium include various optical disks, magnetic tapes, and the like. The recording medium can be widely applied.

  When the operator selects the contour cutting menu when setting the machining conditions, the machining data creation device 2 accepts input of parameters such as the z-axis pitch necessary for the contour cutting, and the z-axis coordinate value is a constant plane. A tool trajectory is generated every time (hereinafter referred to as an xy plane), and the generated tool trajectory is connected to generate an entire tool trajectory so that the amount of tool movement is shortened.

  In this case, a workpiece to be machined is sequentially cut stepwise to finally obtain a target shape, and each tool trajectory is obtained at each step. In the following description, each stage is referred to as a process.

  FIG. 1 is a flowchart showing a processing procedure related to processing data creation processing by a processing program. When the operator selects an execution menu, the processing data creation device 2 moves from step SP1 to step SP2 and is designated by the operator. A tool trajectory for contour cutting of a processing object is created by a reverse offset method using a tool, z coordinate pitch, or the like. The reverse offset method is a method of generating each tool trajectory of the preceding process by sequentially going back from the tool trajectory for obtaining the final machining shape.

  FIG. 3 is a schematic diagram showing a tool trajectory generated by the inverse offset method. In the inverse offset method, first, the coordinate value is offset by the tool radius in the normal direction of the final machining surface of the workpiece to be machined, and the tool locus P3 related to the final machining is generated by continuation of the offset coordinate values. . Further, the tool path P2 of the previous process offset by a predetermined amount in the normal direction with respect to the tool path P3 is generated, and the tool path P1 is generated in the same manner. For the tool trajectories P1, P2, and P3 generated in this way, the tool is sequentially moved in the order of P2 and P3 from the tool trajectory P1 having a large distance from the final machining surface, thereby cutting the workpiece sequentially by a predetermined amount. Finally, the final processed surface can be obtained. In addition, although this Example demonstrates the case where three tool locus | trajectories P1-P3 are produced | generated, the number of tool locus | trajectories is not restricted to this, In short, the several tool locus | trajectory which reaches the tool locus | trajectory P3 which concerns on final machining is produced | generated. You can do that.

  When the tool trajectories P1, P2, and P3 are generated for each xy plane in step SP2, the machining data creation device 2 moves to step SP3, and among the tool trajectories P1, P2, and P3 generated in step SP2, it is for final machining. The tool trajectories P1 and P2 of the previous process are corrected so that the engagement angle becomes constant in the cutting of the next process, except for the tool trajectory P3. The engagement angle refers to an angle (cutting participation angle) in the rotation direction of the tool when the cutting blade of the tool actually cuts the workpiece.

  That is, FIG. 4 is a schematic diagram showing the relationship between the previous machining surface left in the process immediately before the final machining and the tool moving the tool path P3 related to the final machining. The engagement angle is determined by three variables, that is, a tool trajectory along which the center of the tool moves (tool trajectory P3 related to final machining in FIG. 4), its pre-machined surface, and the tool radius. In this case, since the tool path P3 and the tool radius are fixed values, the shape of the pre-machined surface is controlled to set the engagement angle to a constant value α. That is, it is necessary to leave a pre-processed surface by cutting in the previous process so that the engagement angle becomes constant when the tool moves on the tool path P3 related to the final process. The tool locus P2 is corrected so that such a pre-machined surface remains. When the correction of the tool trajectory P2 is completed, the tool trajectory P1 in the previous process is similarly corrected so that the engagement angle becomes constant when the tool moves along the corrected tool trajectory P2.

  When the correction of the tool paths P1 and P2 generated for each xy plane is completed in this way, the machining data creation device 2 moves to step SP4 to perform the corrected tool paths P1 and P2 and the final machining. NC data (machining data D3) relating to the entire workpiece is created by connecting the tool trajectory P3 so that the amount of movement of the tool between the xy planes becomes shorter.

  Thus, when the machining data D3 is created, the machining data creation device 2 moves to step SP5 and ends this processing procedure.

  Next, a specific method for correcting the tool path for making the engagement angle α constant will be described. FIG. 5 is a schematic diagram showing a correction method for correcting the tool path P2 in the immediately preceding process so that the engagement angle of the tool (radius r) that moves the tool path P3 related to the final machining is set to a constant value α. It is.

  In this correction method, the tool trajectory P2 in the immediately preceding process of the tool trajectory P3 is set to o (i), and the tool trajectory o (i) is moved in the normal direction by a distance x (i). When the tool moving on the tool trajectory P3 cuts the pre-machined surface generated by moving the tool trajectory on the moved tool trajectory in the next cutting process (process related to final machining), the engagement angle is The distance x (i) is obtained so as to be the target value α (constant). Here, the engagement angle is expressed as f (x (i)) as a function of the distance x (i).

  A point Q (i) on the pre-machined surface that can be obtained at the moment when the tool passes the point P (i) obtained by moving (correcting) the tool locus o (i) by a distance x (i) in the normal direction to the tool locus. By obtaining, the engagement angle f (x (i)) in this case is obtained. A distance x (i) is determined such that f (x (i)) becomes the target value α.

  That is, since the engagement angle is a constant value α, f (x (i)) = α, which is e (x (i)) = 0 when e (x) = f (x) −α. Is equivalent to solving This equation is solved using Newton's method.

  First, f (x (i)) and e (x (i)) are obtained. In this case, x (i-1) is used as the initial value of x (i).

  Next, f (x (i) + dx) is calculated (dx << 1),

Thus, de / dx (x (i)) is obtained. Thereby, the change amount of the engagement angle f (x (i)) with respect to the change amount of the distance x (i) is obtained.

  This gives the following formula:

To update the distance x (i).

  Further, e (x (i)) is obtained again using the updated distance x (i), and when this result is equal to or less than a specified value, the distance x (i) at which the engagement angle becomes a constant value α is obtained. As a result, the calculation is terminated. On the other hand, if e (x (i)) is greater than or equal to the specified value, it means that the engagement angle has not yet become α, and again returns to the equation (1) to the distance x (i). An engagement angle f (x (i)) when the minute distance dx is added is obtained. Needless to say, in such correction processing of the tool path, it is determined whether or not overcutting is caused by the corrected tool path.

  In this way, while changing the distance x (i) by the minute distance dx, the distance at which the engagement angle f (x (i)) is α, that is, the distance at which e (x (i)) is equal to or less than the specified value is set. All point sequences o (i) (i = 1,..., N) of the locus P2 are obtained.

  Thus, the tool path P2 is corrected, and the pre-machined surface formed when the tool is moved along the tool path P2 always has a constant engagement angle with respect to the tool moving along the tool path P3 related to the final machined surface. It becomes the processing surface that becomes.

  FIG. 6 is a schematic diagram showing the tool trajectory created in this way. With respect to the tool path P3 related to the final machining of the workpiece to be cut, the tool path P2 related to the previous process is corrected as indicated by a solid line, and the tool path P1 related to the previous process is further corrected. The

FIG. 7 is a cross-sectional view showing an experimental example in which the workpiece 12 is cut with a constant engagement angle by the end mill 11 having a diameter of 6 [mm]. In this case, an arc with a radius of 6 [mm] is 1
The shape that is continuous at a pitch of 2 [mm] is the final machining shape, and the cutting margin by linear cutting is used.
Control is performed so that the engagement angle is constant with reference to the engagement angle in the case of 0.2 mm. As a result, as shown in FIG. 8, as a result of the cutting process in the process immediately before the final machining, the machining margin for the final machining is 0.293 [mm] at the maximum at the convex part and the minimum at the concave part.
0.148 [mm].

  By moving the end mill 11 along the tool trajectory related to the final machining in a state where such a margin for cutting remains, the end mill 11 can perform the cutting with a constant engagement angle. FIG. 9A is a characteristic curve diagram showing a change with time of the cutting resistance Fxy applied to the end mill 11 when the engagement angle is constant, and FIG. 9B is a characteristic curve when the cutting margin is constant, that is, the engagement angle. It is a characteristic curve figure showing change with time of cutting resistance Fxy added to end mill 11 when changes. As shown in FIG. 9, the change in the cutting force Fxy applied to the end mill 11 when the engagement angle is constant (FIG. 9A) is sufficiently larger than that when the engagement angle is changed (FIG. 9B). Becomes smaller.

  FIG. 10 (A) is a characteristic curve diagram showing the relationship between the measured value on the xy plane and the design value when the engagement angle is fixed, and FIG. 10 (B) shows the cutting margin. It is a characteristic curve diagram showing the relationship between the measured value and the design value of the machined surface in the normal case where it is constant, that is, when the engagement angle changes. As shown in FIG. 10, when the engagement angle is constant, a machined surface accuracy closer to the design value can be obtained.

(2) Operation of Example In the above configuration, in this CAM system 1 (FIG. 2), shape data D1 representing the shape of a machining target such as a mold is supplied from a CAD system or the like, and calculation in machining data creation device 2 By processing, processing data D3 used for processing of the NC cutting device is created based on the shape data D1. In the CAM system 1, by driving the NC cutting device with the machining data D3, it is possible to create a die having an outer shape based on the shape data D1.

  In creating the machining data D3 in this way, in the CAM system 1, the tool trajectory P3 related to the final machining by the inverse offset method with respect to the machining target surface based on the shape data D1 first, and the tool related to the previous machining. Tool trajectories P1 to P3 are created in the order of the trajectory P2 and the tool trajectory P1 related to the immediately preceding machining.

  Among the created tool paths P1 to P3, the tool path P3 related to the final machining is used as NC data as it is, whereas the tool paths P2 and P1 related to the previous process are used for the respective tool paths. The machining surface obtained by moving the tool on P1 and P2 is corrected so that the engagement angle is constant with respect to the tool moving on the next tool path.

  Therefore, when the cutting is performed while the tool moves on the next tool path P2 on the machining surface obtained by moving the tool along the corrected tool path P1, the engagement angle with respect to this tool becomes constant, and this Since the tool path P2 is also corrected in the same manner, the machining surface obtained by moving the tool along the tool path P2 is obtained when the tool moves on the tool path P3 related to the next final machining. The engagement angle with respect to the tool is constant.

  Thus, when the engagement angle with respect to the tool is always constant, the cutting resistance applied to the tool during the movement of the tool is constant without changing the feed rate of the tool according to the machining shape. When the cutting resistance becomes constant, a uniform machined surface can be obtained, and an error with respect to the machining target value can be reduced. Thus, it is possible to perform machining with high accuracy while keeping the feed rate of the tool constant, thereby increasing machining efficiency.

(3) Advantages of the embodiment According to the above configuration, by performing the cutting process with the engagement angle being constant, the cutting resistance can be made substantially constant even if the feed rate of the tool is constant, High precision machining can be performed efficiently.

(4) Other Embodiments In the above-described embodiments, the case where a two-dimensional free shape is machined by a straight end mill has been described. However, the present invention is not limited to this, and the present invention is applied to a case where contour finishing is performed by a ball end mill. Even in this case, the same effect as described above can be obtained.

  Further, in the above-described embodiment, the case where the engagement angle is made constant when performing machining on each xy plane with respect to the tool trajectory of contour cutting is described. However, the present invention is not limited to this, and is in xyz space. In the case of obtaining the tool trajectory, the same effect can be obtained if the engagement angle is controlled to be constant based on the feed direction of the tool.

  Further, in the above-described embodiment, a case has been described in which tool trajectories are generated for all xy planes, and then these tool trajectories are corrected so that the engagement angle is constant. However, the present invention is not limited to this, and xy Tool trajectory creation and correction may be performed for each plane.

  In the above-described embodiment, the case where the engagement angle is made constant for the final processing and the processing before that is described. However, the present invention is not limited to this, and only the final processing is performed so that the engagement angle is constant. However, the same effect can be obtained.

  In the above-described embodiments, the case where the tool path is corrected so that the engagement angle is constant has been described. However, the present invention is not limited to this, and the engagement angle may be corrected so as to be equal to or less than a predetermined value. .

  In the above-described embodiments, the case where the tool path once created is corrected has been described. However, the present invention is not limited to this, and the tool path may be created so that the engagement angle is constant in the stage of creating the tool path. .

  In the above-described embodiment, the case where the present invention is applied when generating NC data to be supplied to the NC machine tool as the machining data D3 has been described. However, the present invention is not limited thereto, and the calculation unit of the NC machine tool is described. Then, the processing may be performed while correcting the supplied NC data so that the engagement angle becomes constant.

  In the above-described embodiments, the present invention is applied when performing contour line processing. However, the present invention is not limited to this and can be widely applied to other processing.

  Further, in the above-described embodiments, the case where the present invention is applied when creating a mold has been described. However, the present invention is not limited thereto, and various metal products can be used as products when creating mock-up products. The present invention can be widely applied to a case where a cutting material is cut with a shape represented by shape data as a processing target, such as when processing.

  The present invention relates to a machining data creation method, a machining data creation program, and a recording medium on which the machining data creation program is recorded, and can be applied to, for example, a CAM system.

It is a flowchart which shows the process data creation process procedure which concerns on the Example of this invention. It is a block diagram which shows the CAM system which performs the process data creation process of FIG. It is a basic diagram which shows the production | generation method of the tool locus | trajectory by a reverse offset method. It is a basic diagram with which it uses for description of the element which determines an engagement angle. It is an approximate line figure used for explanation of a correction method of a tool locus. It is a basic diagram which shows the tool locus | trajectory after correction. It is sectional drawing which shows the end mill and process shape by a predetermined process condition. It is sectional drawing which shows the cutting margin which remains when a tool is moved along the tool locus after correction. It is a characteristic curve figure which shows the cutting resistance F before and behind correction. It is a characteristic curve figure which shows the processing shape before and behind correction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... CAM system, 2 ... Machining data creation device, 3 ... Display device, 4 ... Input device, D1 ... Shape data, D3 ... Machining data, P1-P3 ... Tool locus

Claims (5)

In the machining data creation method for creating tool trajectory data for cutting that sequentially cuts the machining target step by step and finally forms the target shape,
A machining data creation method, comprising: creating a previous tool path so that an engagement angle of a tool moving along at least a tool path related to final finishing is a predetermined value or less. The step of creating the tool path includes
The machining data creation method according to claim 1, wherein a tool path formed by offsetting a tool path related to the final finishing by a predetermined amount is corrected. The step of creating the tool path includes
The machining data creation method according to claim 1, wherein a correction position at which the engagement angle becomes a predetermined value or less is obtained while moving each point on the tool trajectory in the previous stage by a predetermined amount in the normal direction. In a program for causing a computer to execute a predetermined processing procedure,
The program is
A machining data creation program for creating tool trajectory data for cutting that sequentially cuts a processing target step by step and finally forms a target shape,
A machining data creation program comprising: a step of creating a previous tool trajectory so that an engagement angle of a tool moving along at least a tool trajectory relating to final finishing is a predetermined value or less. The recording medium which recorded the process data creation program of Claim 4.

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