DE112020000656T5 - Machining program converting apparatus, numerical control, machining program converting method and machine learning apparatus - Google Patents

Abstract

A machining program conversion apparatus (100) comprises: a curved path generation unit (104) that generates a curved path (TP) between a plurality of command points (P) on a tool path; an input unit for allowable dimensional tolerances (107), where values are inputted which define an allowable range for a distance (L) between an evaluation point (Q) on the curved path (TP) and a reference point (C); a curved path evaluation unit (108) that determines whether or not the distance (L) is within the allowable range; a tool path changing unit (109) that, when the distance (L) is out of the allowable range, shifts only the evaluation point deviating from the allowable range until the distance (L) is within the allowable range, and the evaluation point that is moved than sets a new command point (R) when changing the toolpath; and an output unit for the converted machining program (110) which converts the changed tool path into a program to be output to an external device.

Description

Area

The present disclosure relates to a machining program converting device that converts a machining program for numerical control, and it also relates to a numerical controller, a machining program converting method, and a machine learning device.

background

In order to machine a workpiece with a numerical control, a numerical control machining program (hereinafter referred to simply as “machining program”) is used. The machining program includes a description of movement commands for moving a workpiece or a tool attached to a machining tool controlled by the numerical controller (hereinafter referred to simply as “numerically controlled machining tool”) along a preset path. The machining program is generated, for example, by a commercially available system for computer-aided design (CAD) or for computer-aided production (CAM), and it is described in a predetermined character string format, such as G code or macro statements.

Machining a workpiece into a shape that has a freeform surface conventionally involves creating, virtually with the CAD / CAM system, an ideal path along which a tool is moved while it is in contact with a curved surface to be machined (hereinafter simply referred to as "machining curve surface"), is in the form of a sequence of command points using the machining program. The editing further includes creating an approximate path with small line segments, one between each command point, and then moving the tool along the tool path using the numerically controlled editing tool.

The tool path that is output by the CAD / CAM system is described in the machining program as the G-coded movement commands that can be interpreted by the numerical control. The machining program is entered into the numerical control of the numerically controlled machining tool. The numerical control reads and interprets the machining program and generates interpolation data from the movement commands after carrying out movement path interpolation during each interpolation period. Using the generated interpolation data, the numerical controller controls axes of the numerically controlled machining tool to move the tool to desired positions and thereby machine the workpiece.

When the tool path generated by the procedure described above is used in machining, machining is performed along linear interpolation paths represented by the small line segments, resulting in a decrease in machining quality. If such a case occurs, a fitted or adapted curve path is generated from the tool path, which subsequently runs through interpolations for processing. In this way, a smooth machining result can be expected.

For example, the tool path generation method disclosed in Patent Literature 1 includes a plurality of equally spaced target points on a tool path, calculating a fitted curve based on the plurality of target points, and generating a tool path along the fitted curve.

List of citations

Patent literature

Patent Literature 1: laid-open Japanese Patent Application No. 2011-96077

overview

Technical problem

In the tool path generating method and a tool path generating device described in Patent Literature 1, since the fitted curve path is generated from the tool path formed by small line segments, it does not ensure that the generated curve path is fitted to a desired machining curve surface, which, problematically leads to a machining result which is very different in terms of shape from the desired machining curve surface. Since additional machining is necessary when machining accuracy is undesirable, a process takes place in which the CAD / CAM system is returned to generate a tool path again and a machining program is reissued, which leads to a decrease in the work efficiency of a worker.

The present disclosure has been made in order to solve the above problems, and it is an object of the present disclosure to provide a machining program conversion device and a to provide numerical controls which enable improved machining accuracy for a result of machining a workpiece.

the solution of the problem

In order to solve the above problem and achieve the object, a machining program conversion apparatus according to the present disclosure includes: a curved path generation unit for generating a curved path between a plurality of command points based on a tool path generated by a machining program in which movement commands for a Tool are described, the plurality of command points being provided on the tool path in accordance with the move commands; an input unit for allowable dimensional tolerances, where values are entered which define an allowable range for a distance L between an evaluation point on the curve path and a reference point, the evaluation point being provided for determining whether or not a tool is moving along a machining curve surface, the corresponds to an end surface of the workpiece when following the curve path, the reference point being a point of contact between the tool and the machining curve surface; a curved path evaluation unit for determining whether or not the distance L is between the values defining the allowable range and inputted to the allowable dimensional tolerance input unit; and a tool path changing unit for, when the distance L is out of the allowable range, shifting the evaluation point deviating from the allowable range until the distance L is within the allowable range and an evaluation point that is displaced as one to set a new command point when changing the tool path.

Further, a numerical controller according to the present embodiment comprises: a curved path generating unit for generating a curved path between a plurality of command points based on a tool path generated by a machining program in which movement commands for a tool are described, the plurality of command points being the tool path is provided in accordance with the move commands; an input unit for allowable dimensional tolerances, where values are entered which define an allowable range for a distance L between an evaluation point on the curve path and a reference point, the evaluation point being provided for determining whether a tool is moving along a machining curve surface which is an end surface of the workpiece when following the cam path, the reference point being a point of contact between the tool and the machining cam surface; a curved path evaluation unit for determining whether or not the distance L is between the values defining the allowable range and inputted to the allowable dimensional tolerance input unit; and a tool path changing unit for, when the distance L is out of the allowable range, shifting the evaluation point deviating from the allowable range until the distance L is within the allowable range and an evaluation point that is displaced as one to set a new command point when changing the tool path.

Advantageous Effects of the Invention

The machining program converting device according to the present disclosure enables improved machining accuracy in a result of machining the workpiece by changing the tool path so that the distance between the evaluation point of the curve path and the reference point on the machining curve surface is within the allowable range.

The numerical control according to the present disclosure is able to perform numerical control in accordance with the changed tool path, which enables improved work efficiency.

Figure list

• 1 Fig. 13 shows a configuration of a machining program converting device according to a first and a second embodiment.
• 2 Fig. 13 is a flow chart showing the operation of the machining program converting device according to the first embodiment.
• 3 FIG. 13 shows an example of a tool path that the machining program converting device according to the first embodiment has read from a machining program.
• 4th Fig. 13 shows an example of a curved path generated in accordance with the curved path read from the machining program by the machining program converting device according to the first embodiment.
• 5 Fig. 13 shows an example of a tool moving along a tool path in the first embodiment, the second embodiment, and a third embodiment.
• 6th FIG. 13 shows an example of a final shape to be obtained by machining using the tool path of the machining program converting device according to the first embodiment.
• 7th Fig. 13 is a cross-sectional view showing a state in which the curved paths are arranged to correspond to the final shape in the machining program converting device according to the first embodiment.
• 8th Fig. 13 shows the tool removed from a machining curve surface in the machining program converting device according to the first embodiment, the tool in this example being a spherical mill.
• 9 Fig. 13 shows the tool in contact with the machining cam surface in the machining program converting device according to the first embodiment, the tool being the spherical mill in this example.
• 10 Fig. 13 shows the tool as it intersects with the machining cam surface in the machining program converting device according to the first embodiment, the tool being the spherical mill in this example.
• 11th Fig. 13 shows a tool removed from a machining cam surface in the machining program converting device according to the first embodiment, the tool being a disk milling cutter in this example.
• 12th Fig. 13 shows the tool in contact with the machining cam surface in the machining program converting device according to the first embodiment, the tool being the disk milling cutter in this example.
• 13th Fig. 13 shows the tool that intersects with the machining cam surface in the machining program converting device according to the first embodiment, the tool being the side milling cutter in this example.
• 14th Fig. 13 shows a tool removed from a machining curve surface in the machining program converting device according to the first embodiment, the tool being a corner radius mill in this example.
• 15th Fig. 13 shows the tool in contact with the machining cam surface in the machining program converting device according to the first embodiment, the tool being the corner radius cutter in this example.
• 16 Fig. 13 shows the tool as it intersects with the machining curve surface in the machining program converting device according to the first embodiment, the tool being the corner radius cutter in this example.
• 17th Fig. 13 shows an example of shifting an evaluation point to allow the tool to stay in contact with the machining curve surface for adding a new command point in the machining program converting device according to the first embodiment.
• 18th Fig. 13 shows a changed tool path obtained by adding the new command point in the machining program converting device according to the first embodiment.
• 19th Fig. 13 is a flow chart showing the operation of the machining program converting device according to the second embodiment.
• 20th Fig. 13 shows an example of a tool path of the machining program converting device according to the second embodiment as read by the machining program.
• 21 Fig. 13 shows an example of a curved path between two of three adjacent command points after deleting a central command point in the machining program converting device according to the second embodiment.
• 22nd Fig. 13 shows an example of a final shape to be obtained by machining using the tool path of the machining program converting device according to the second embodiment.
• 23 Fig. 13 is a sectional view showing a state in which the curved path is arranged to correspond to the final shape in the machining program converting device according to the second embodiment.
• 24 Fig. 13 shows the tool removed from a machining curve surface in the machining program converting device according to the second embodiment, the tool being the spherical mill in this example.
• 25th Fig. 13 shows the tool in contact with the machining cam surface in the machining program converting device according to the second embodiment, the tool being the spherical mill in this example.
• 26th shows the tool what happens to the machining curve surface for the The machining program converting device of the second embodiment overlaps, the tool being the spherical mill in this example.
• 27 Fig. 13 shows an example of a modified tool path obtained by deleting the command point from the tool path in the machining program converting device according to the second embodiment.
• 28 Fig. 13 shows a configuration of a numerical controller according to the third embodiment.
• 29 Fig. 13 is a flow chart showing an operation of the numerical controller according to the third embodiment.
• 30th FIG. 13 shows a configuration of an example of a machine learning apparatus according to a fourth embodiment.

Description of embodiments

Machining program conversion devices, a numerical controller, machining program conversion methods, and machine learning apparatus according to embodiments of the present disclosure will now be described with reference to the drawings. It should be noted that these embodiments are not restrictive.

First embodiment.

1 Fig. 13 shows a configuration example of a machining program converting device according to the first embodiment. The machining program conversion device 100 comprises: a machining program input unit 101 which a machining program entered from outside receives; a machining program analyzer 102 which analyzes the input machining program and determines a tool path; a tool path storage unit 103 which the machining program analyzer 102 saves specific toolpath; a curved path generation unit 104 which is in accordance with that in the tool path storage unit 103 saved toolpath creates a curve path; a tool data input unit 105 where tool data is entered; a shape data input unit 106 where data is entered on a shape to be obtained after machining a workpiece; an input unit for permissible dimensional tolerances 107 where an allowable range for a distance between a point on the curve path and a machining curve surface is entered, the point being provided for determining whether or not a tool moves along the machining curve surface on the workpiece; a curve path evaluation unit 108 which determines whether or not the distance between the point on the curve path and the machining curve surface is in the allowable range; a tool path changing unit 109 that changes the toolpath; and an output unit for the converted machining program 110 . The output unit for the converted machining program 110 converts the changed tool path into a machining program for output to a numerical control 111 around which is an external device. While the external device is described as the numerical controller in the present embodiment, the external device is not limited to the numerical controller and may be, for example, a program checking device or a tool path display device.

2 Fig. 13 is a flowchart showing an example of the operation of the machining program converting device 100 according to the first embodiment shows. With reference to 2 there will be described a machining procedure that the machining program converting device 100 for creating and modifying a toolpath.

The tool path creating operation of the machining program converting device 100 starts with the input of a machining program into the machining program converting device 100 (Step S101). For this purpose, the machining program input unit reads 101 the machining program conversion device 100 the machining program that controls a machining tool from outside. The machining program is a description of movement commands for moving a workpiece or a tool to be machined along a preset path.

The machining program is entered in step S101 when, for example, a file is read in in G code format that was output by a CAD / CAM system. Alternatively, the machining program is created by a worker who inputs necessary information using an input device such as a keyboard.

Then the machining program analyzer analyzes 102 the machining program conversion device 100 the machining program obtained in step S101 and determines a tool path described in the machining program (step S102). In particular, the machining program, which is described in, for example, G code, Toolpath information read. The read tool path is stored in the tool path storage unit 103 stored (step S103). 3 Fig. 10 shows an example of the tool path converted by the machining program. The toolpath in 3 includes command points P1 to P6 and straight lines with a straight line between each command point. The command points here designate points that are commanded in the machining program. The distance between the command points is predetermined in the machining program.

Then the curved path generating unit generates 104 Curve paths each lying between the adjacent command points in accordance with that in the tool path storage unit 103 stored tool path (step S104). 4th Fig. 10 shows an example of the curve paths created in accordance with the tool path containing the points P1 to P6 includes. In the 4th curve paths shown TP1 until TP6 are created so that the tool moves along these through the command points.

The curved paths that the machining program converter 100 generated need not be the same as curved lines with those of the numerical control device 111 works, ie curved lines that make it numerical control 111 allow to work out a shape from the workpiece to be machined. Therefore, the turning path generating method is preferably the same as a turning path generating method of the numerical control 111 into which the machining program converting device 100 entered machining program is finally entered. For example, a method of interpolating a spline curve passing through the command points is another example of the curve path generating method.

Tool data are entered in the tool data input unit 105 input from outside (step S105). The tool data is information defining a shape of the tool machining the workpiece, and it includes information representing a tool type and information representing a tool shape such as a tool diameter, a tool corner radius and a tool length. For example, if the tool has a tapered shape, the tool data input unit 105 Information can be supplied, such as an angle of inclination of a generating line at a tool outer edge with respect to a central axis of the tool. The tool data input unit 105 For example, information can be supplied to a tool that has an asymmetrical shape, such as a rotary tool. The input from the outside is done by a worker who inputs the data using the keyboard, for example, or by a method such as conversion from CAD data. The machining program converting device is based on this tool data 100 able to generate a tool model. 5 shows an example of the tool moving along the tool path. The tool T10 has the shape of a spherical mill and is generated based on the tool data.

The shape data become the shape data input unit 106 input from outside (step S105). The shape data is information that defines a shape that should be obtained after machining the workpiece. This information enables the creation of a final shape for which the workpiece is intended. The final shape includes a machining curve surface S1 which is a curved surface to be machined. The final shape is a shape of an ideal machined product that should result from the machining that the machining tool performs on the workpiece in accordance with the machining program. The processing tool processes the workpiece in such a way that fewer deviations remain between the final shape and the processed product. The external input is done by the worker entering the data using the keyboard, for example, or by a method such as conversion from CAD data.

6th Figure 13 is an example of the final shape to be obtained by machining using the tool path. In the 6th The final shape M1 shown is generated based on the shape data received from the shape data input unit 106 and includes the machining cam surface S1 .

7th Fig. 13 is a cross-sectional view showing a state in which the curve paths are arranged to correspond to the final shape M1, with evaluation points Q1 until Q5 on the curve path TP3 are set by way of example. Here, the evaluation points denote points that are provided on the curved path in order to determine whether or not the workpiece moves along the machining curve surface on the workpiece when it follows the curved path. The evaluation points are determined, for example, as selected points on the curve path so that curve parameters are evenly spaced, or by iteration that is performed until a maximum deviation between a line segment connecting adjacent evaluation points and the curve path becomes equal to or less than a predetermined value.

the 8th until 10 each show a relationship between the tool and the Machining curve surface S1 if the tool is a spherical mill (hereinafter referred to as “tool T10”). 8th shows the tool T10 away from the machining curve surface S1 . In 8th is a point on the machining curve surface S1 where there is a gap between the tool T10 and the machining curve surface S1 is the smallest, referred to as a reference point C1. The reference point C1 on the machining curve surface S1 also lies where there is a distance between the evaluation point Q that lies on the tool in step S106 (described below) and the machining curve surface S1 is the shortest. The distance between the evaluation point Q and the reference point C1 is referred to here as "distance L1 " Are defined.

9 shows the tool T10 in contact with the machining curve surface S1 . In 9 is a contact point between the tool T10 and the machining curve surface S1 as a reference point C2 Are defined. The reference point C2 is also a cutting point when machining via the machining curve surface S1 with the tool T10 . A distance L2 between the evaluation point Q and the reference point C2 is the ideal value when the workpiece is machined by the machining tool.

10 shows the tool T10 how about the machining curve surface S1 overlaps. In 10 is a point on the machining curve surface S1 where a distance between the evaluation point Q on the tool T10 and the machining curve surface S1 is shortest as a reference point C3 Are defined. If the tool intersects with the machining curve surface, as in this case, the tool is offset until the tool comes into contact with the machining curve surface, which results in a contact point between the displaced tool and the machining curve surface as the reference point C3 is determined. In 10 can be the reference point C3 also as the point of contact between the relocated tool T10 represented by a dashed line and the machining curve surface S1 are designated. The distance between the evaluation point Q and the reference point C3 is defined here as "distance L3".

An allowable range for the distance L will now be described when it is assumed that the distance L2 2.00 mm. If a dimensional tolerance for the machining curve surface on the workpiece is ± 0.05 mm compared to a standard tolerance, the result for the distance L1 is 2.0 mm <distance L1 2.05 mm and for the distance L3 1.95 mm ≤ distance L3 <2.0 mm. Therefore the permissible range for the distance L is 1.95 mm ≤ distance L ≤ 2.05 mm.

During the evaluation point Q on the tool T10 on a central axis of the tool T10 near a front end of the tool T10 in the 8th until 10 is arranged, the evaluation point may Q for example at the front end of the tool at a part or point on the tool T10 be located where the tool is being machined, or it can be at a point on the tool T10 be placed where the distance between the tool T10 and the machining curve surface S1 is the shortest. It should be noted, however, that after a certain position on the tool as the evaluation point Q is determined, the particular evaluation point Q which is where the distance L is evaluated.

The permissible range for the distance L is entered in the input unit for the permissible dimensional tolerances 107 is input (step S105). Values that define the allowable range are determined depending on the machining accuracy that is intended for the workpiece. When the shape data entered in the shape data input unit 106 are inputted contain information on a machining tolerance with respect to the machining cam surface on the workpiece, the values indicating the allowable range can be determined in accordance with the machining tolerance. In this case, the automatic ranging depending on the working area is enabled, resulting in improved working efficiency. The allowable range for the distance L can also be referred to as an allowable dimensional tolerance.

These values, those of the input unit for permissible dimensional tolerances 107 can define an allowable range for the shortest distance between the tool and the end face. For example, if the dimensional tolerance for a machining curve surface on a workpiece is ± 0.05 mm compared to a standard tolerance, the shortest distance between the tool and the machining curve surface of a final shape should be within 0.05 mm, so that the values are 0.05 mm if the permissible range is defined.

While the allowable range for the distance L in the present embodiment is entered into the allowable dimensional tolerance input unit 107 is input, values defining the allowable range for the distance L can be stored in an allowable dimensional tolerance storage unit (not shown) of the machining program converting device 100 be saved in advance.

the 11th until 13th each show a relationship between a tool and a Machining curve surface S2 if the tool is a side milling cutter (hereinafter referred to as “tool T11 "Labeled). 11th shows the tool T11 away from the machining curve surface S2 . In 11th is a point on the machining curve surface S2 where there is a gap between the tool T11 and the machining curve surface S2 is shortest as a reference point C2 Are defined. A distance between the evaluation point Q and the reference point C11 is called a "distance L11 " Are defined.

12th shows the tool T11 in contact with the machining curve surface S2 . In 12th is a point of contact between the tool T11 and the machining curve surface S2 as a reference point C12 Are defined. A distance L12 between the evaluation point Q and the reference point C12 is the ideal value when the workpiece is machined by the machining tool.

13th shows the tool T11 as is the case with the machining curve surface S2 overlaps. In 13th is a point on the machining curve surface S2 where a distance between the evaluation point Q on the tool T11 and the machining curve surface S2 is shortest as a reference point C13 Are defined. In the case of the tool that intersects with the machining curve surface, as can be seen in this case, the tool can be displaced inward until the tool comes into contact with the machining curve surface. In 13th can be the reference point C13 also as a contact point between the relocated tool T11 indicated by a dashed line and the machining curve surface S2 are designated. The distance between the evaluation point Q and the reference point C13 is defined as "Distance L13".

During the evaluation point Q on the tool T11 in a center of a leading edge of the tool T11 in the 11th until 13th is arranged, the evaluation point may Q for example at a part or a point on the tool T11 be arranged where the workpiece machining takes place, or at a point on the tool T11 where the distance between the tool T11 and the machining curve surface S2 is the shortest. It should be noted, however, that when a certain position on the tool as the evaluation point Q is set, the evaluation point Q the point is where the distance L is evaluated.

the 14th until 16 show a relationship between a tool and a machining curve surface S3 if the tool is a corner radius cutter (hereinafter referred to as “tool T12”). 14th shows the tool T12 away from the machining curve surface S3 . In 14th is a point on the machining curve surface S3 where there is a gap between the tool T12 and the machining curve surface S3 is shortest as a reference point C21 Are defined. A distance between the evaluation point Q and the reference point C21 is called "distance L21 " Are defined.

15th shows the tool T12 in contact with the machining curve surface S3 . In 15th is a contact point between the tool T12 and the machining curve surface S3 as a reference point C22 Are defined. A distance L22 between the evaluation point Q and the reference point C22 is the most ideal value when the workpiece is machined by the machining tool.

16 shows the tool T12 how about the machining curve surface S3 overlaps. In 16 is a point on the machining curve surface S3 where a distance between the evaluation point Q on the tool T12 and the machining curve surface S3 is shortest as a reference point C23 Are defined. If the workpiece intersects with the machining curve surface, as is the case here, the tool can be displaced inwards until the tool comes into contact with the machining curve surface. In 16 can be the reference point C23 also as a contact point between the relocated tool T12 indicated by a dashed line and the machining curve surface S3 are designated. The distance between the evaluation point Q and the reference point C23 is called "distance L23 " Are defined.

During the evaluation point Q on the tool T12 on the central axis of the tool T12 near the front end of the tool T12 in the 14th until 16 is arranged, the evaluation point may Q for example at a part or point on the tool T12 be arranged where the workpiece machining takes place, or at a point on the tool T10 where the distance between the tool T12 and the machining curve surface S3 is the shortest. It should be noted, however, that after a certain position on the tool as the evaluation point Q is set, the set evaluation point Q the point is where the distance L is evaluated.

Then the curve path evaluation unit evaluates 108 each of the curve paths TP made by the curved path generation unit 104 in accordance with the tool data, shape data and the values defining the allowable area and inputted to the allowable dimensional tolerance input unit (step S106). A multitude of evaluation points on the curve paths TP1 until TP6 is determined first. Then, as in the 8th until 16 based on the entered in step 5 Tool data generated tool arranged in such a way that it contains each of the specified evaluation points Q is equivalent to. Ideally, the tool should be when it is at the evaluation point Q is arranged to be in contact with the machining curve surface of the final shape.

The curve path evaluation unit 108 evaluated for the curve path TP whether a value of each distance L is in the allowable range. If one of the for the curve path TP certain distances L exceeds the permissible range for the distance L, the given curve path must TP are changed, and step S107 (described below) follows. If the for every curve path TP predetermined distances L are within the allowable range for the distance L, step S108 (described below) follows.

When one of the distance values L is the allowable range for the distance L in the curved path evaluation unit 108 exceeds, that is, if “NO” in step S106, the tool path is changed (step S107). With reference to 17th Here will be described a tool path changing operation taking, for example, a case where the tool T10 the ball end mill is in a state as shown in 10 it is shown where the tool meets the machining curve surface S1 overlaps.

17th shows an example of relocating the evaluation point around it to the tool T10 to allow in contact with the machining cam surface S1 to add a new command point. The toolpath change unit 109 first extracts from the evaluation points Q on the curve path TP to be changed and obtained in step S106 becomes the evaluation point Q which deviates most from the permissible range for the distance L. In 17th is the curve path TP3 to change, and from the evaluation point Q3 on the curve path TP3 it is believed to be most of the allowable range for the distance L3 deviates.

Then the evaluation point Q3 relocated so that the tool T10 in contact with the machining curve surface S1 got. The relocated evaluation point is used here as the new command point R1 set. The evaluation point Q3 can here along a tool axis, along a normal to the machining curve surface at the reference point on the machining curve surface at the evaluation point Q3 arranged tool or in any other direction.

Moving the evaluation point Q3 is such that the tool T10 in contact with the machining curve surface S1 is can by repeating a procedure of moving only a very small distance in a given direction and then calculating the distance L3 at the relocated evaluation point Q take place until the distance L3 within the allowable range for the distance L3 falls.

The toolpath change unit 109 adds to that in the toolpath storage unit 103 the relocated evaluation point stored in step S103 Q3 added that as the new command point R1 was put where the distance L3 within the allowable range for the distance L3 falls. The tool path is thus changed. This leads to an improved accuracy in the result of machining the workpiece.

The changed tool path is stored in the tool path storage unit 103 saved. 18th shows the changed toolpath created by adding the new command point R1 to the command points P1 to P6 has been obtained in step S107. After step S107 has been carried out, the system returns to step S104 and the process is repeated. In this case, the process shown in step S105 can be omitted.

When the toolpath change is complete, taking the distance L3 at each evaluation point Q within the allowable range for the distance L3 is in the process shown in step S106, the changed tool path is stored in the tool path storage unit 103 saved. Then the output unit generates for the converted machining program 110 a modified machining program from the one in the tool path storage unit 103 stored path in accordance with the predetermined conversion method, and after this conversion, outputs the changed machining program from the machining program converting device 100 off (step S108).

The process ends when the execution of step S108 ends. The converted machining program that has been output is entered into the numerical control 111 is entered and the workpiece is machined. While steps S106 to S108 have been described for the case in which the tool T10 than the spherical milling cutter with the machining curve surface S1 overlaps, the same applies to the other cases.

The above machining program converting device according to the first embodiment changes the tool path so that the distance L between the evaluation point and the reference point falls within the allowable range for the distance L, and thus enables the improved machining accuracy as a result of machining the workpiece.

Since the new command point is added as a result of the displacement of only the evaluation point where the distance L exceeds the allowable range for the distance L, the command points to be added can be reduced to a required amount. Therefore, slow processing due to an unnecessarily large amount of data in the program can be avoided.

Second embodiment.

A configuration of the machining program conversion device 100 according to the second embodiment is the configuration of the machining program converting device 100 according to the first embodiment are the same and therefore will not be described. The machining program conversion device 100 according to the second embodiment operates according to an in 19th flowchart shown.

Steps S201 to S203 are the same as steps S101 to S103 of the first embodiment in terms of processing. Compared to the first embodiment, the second embodiment has a different curve path generation method.

20th Fig. 13 shows an example of a tool path that the machining program converting device has read from a machining program. The in 20th toolpath shown includes command points P11 to P17 and straight lines each lying between command points. Among the command points generated in step S204 of the present (second) embodiment, there are first, second, and third command points and a curved path between the first command point and the third command point, which serve as end points. 21 shows a curve path TP11 which was generated as an example between P13 and P15, where the command points P13, P14 and P15 are the first command point, the second command point and the third command point, respectively. The tool data are then entered from outside into the tool data input unit 105 is input, and the shape data is entered into the shape data input unit from outside 106 is input (step S205).

The curve path evaluation unit 108 evaluates the distance L at each of a plurality of evaluation points on the curve path TP11 in accordance with the tool data, the shape data and the values indicating an allowable range and inputted to the allowable dimensional tolerance input unit (step S206). In other words, the evaluation is made as to whether the distance L is within or exceeds the allowable range for the distance L. When each distance L1 is within the allowable range for the distance L, it becomes the command point P14 here from the one in the toolpath storage unit 103 stored tool path is deleted (step S207). Since the curve path is to be changed in this case, the curve path becomes TP11 a curved path area which is finally converted and output (step S208).

22nd Figure 13 is an example of a final shape to be obtained by editing using the tool path. In the 22nd The final shape M2 shown is generated based on the shape data inputted by the shape data input unit 106 have been entered, and includes a machining curve surface S4.

A concrete description of step S206 will be given with reference to FIG 23 until 25th . 23 Fig. 13 is a sectional view showing a state in which the curved path is arranged to correspond to the final shape M2, with evaluation points Q11 to Q14 on the curved path as an example TP11 are set. 24 Fig. 13 shows a tool that is in contact with the machining cam surface S4 when the tool is the spherical mill T10 is. In 24 is a contact point between the tool T10 and the machining curve surface S4 is defined as a reference point C31. In 24 is the tool at the evaluation point Q12 on the curve path TP11 arranged, being between the evaluation point Q12 and the reference point C31 is a distance L32.

the 24 until 26th each show a relationship between the tool T10 , which is the spherical milling cutter (hereinafter referred to as “tool T10”), and the machining curve surface S4. The tool TP10 is at the evaluation point Q12 on the curve path TP11 arranged. 24 shows the tool T10 away from the machining curve surface S4. In 24 is a point on the machining curve surface S4 where there is a distance between the tool T10 and the machining curve surface S4 is shortest is defined as a reference point C31. A distance between the evaluation point Q12 and the reference point C31 is defined here as “distance L31”.

25th shows the tool T10 in contact with the machining curve surface S4. In 25th the reference point C32 is the contact point between the tool T10 and the machining curve surface S4. The distance L32 between the evaluation point Q12 and the reference point C32 is the best value when the workpiece is machined by the machining tool.

26th shows the tool T10 as it overlaps with the machining curve surface S4. In 26th is a point on the Machining curve surface S4 where a distance between the evaluation point Q12 on the tool T10 and the machining curve surface S4 is shortest is defined as a reference point C31. When the tool intersects with the machining curve surface, as can be seen in this case, the tool can be displaced until the tool comes into contact with the machining curve surface. In 26th The reference point C31 can also be used as a contact point between the displaced tool T10 represented by a broken line and the machining curve surface S4. The distance between the evaluation point Q12 and the reference point C33 is defined here as a “distance L33”.

When each distance L (each of the distances L31 to L33) is within the allowable range for the distance L in the curved path evaluation unit 108 becomes the command point P14 which is the second command point from that in the tool path storage unit 103 stored tool path is deleted (step S207). Since the curve path is to be changed in this case, the curve path becomes TP11 the tool path area that will eventually be converted and output (step S208). 27 Fig. 13 is an example of a final shape of the tool path changed in the present (second) embodiment.

Even if there is only one evaluation point out of the plurality of evaluation points Q there that on the curve path TP11 are set where the distance L is the allowable range for the distance L in the curved path evaluation unit 108 exceeds the command point P14 not deleted, and a curve path is created between the command points P13 and P14 and a curved path between P14 and P15 is generated (step S209).

Then the curve path evaluation unit evaluates 108 as in the process between steps S106 to S108 of the first embodiment, each of the by the curved path generation unit 104 generated curve paths in which it is determined whether a value of each distance L is within the allowable range in accordance with the tool data, the shape data and the values defining the allowable range and entered via the input unit for allowable dimensional tolerances (step S210). When one of the distance values L is the allowable range for the distance L in the curved path evaluation unit 108 exceeds, that is, if “NO” in step S210, the tool path is changed (step S211). The path change operation here is the same as in the first embodiment.

When the toolpath change is complete, so the distance L at each of the evaluation points Q is within the allowable range for the distance L in the process shown in step S210, the changed tool path is stored in the tool path storage unit 103 saved. Then the output unit generates for the converted machining program 110 a modified machining program from the one in the tool path storage unit 103 stored tool path in accordance with a predetermined conversion method, and after this conversion, gives the changed machining program from the machining program converting device 100 off (step S208).

The above machining program converting device according to the second embodiment deletes the existing central command point, which is one of the three adjacent command points, from the tool path when the distance L between each reference point and the corresponding evaluation point provided on the curve path between the two end points is within of the allowable range for the distance L. Therefore, the machining program can have a reduced amount of data, and improved work efficiency is provided. Furthermore, a result of machining a workpiece can achieve desired machining accuracy.

Third embodiment.

A numerical controller according to the third embodiment will now be described with reference to the drawings. It should be noted that this embodiment is not restrictive.

The numerical control device 200 comprises: a machining program input unit 201 that receives a machining program from outside, a machining program analyzer 202 which analyzes the input machining program and determines a tool path; a tool path storage unit 203 which the machining program analyzer 202 saves specific toolpath; a curved path generation unit 204 showing a curve path in correspondence with that in the tool path storage unit 203 saved toolpath generated; a tool data input unit 205 where tool data is entered; a shape data input unit 206 where data is entered on a shape to be obtained after machining a workpiece; an input unit for permissible dimensional tolerances 207 where an allowable range is entered for a distance between a point on the curve path and a machining curve surface, the point being for determining whether a workpiece is moving along the machining curve surface on the workpiece; one Curve path evaluation unit 208 that determines whether or not the distance between the point on the curve path and the machining curve surface is within the allowable range; a tool path changing unit 209 that changes the toolpath; and a curve path interpolator 210 . When a machining program is entered from outside, the numerical control analyzes 200 According to the present embodiment, the machining program and generates a tool path and outputs the tool path to a motor drive unit 211.

A procedure is described that complies with the 28 numerical control device shown 200 according to the third embodiment for generating a tool path. 29 Fig. 13 is a flowchart showing an example of the operation of the numerical controller 200 according to the third embodiment. The flowchart of the 29 is a machining procedure that the numerical control 200 to generate the toolpath. The procedure between step S301 and step S307 in FIG 29 is the same as the processing procedure between step S101 and step S107 of the first embodiment.

When the distances L at the respective evaluation points Q are within the allowable range for the distance L in step S306, the curved path generation unit outputs 204 these generated curve paths to the curve path interpolator 210 further.

Then the curve path interpolator performs 210 the numerical control 200 Curve path interpolations (step S308). In particular, the curve path interpolator determines 210 a tool moving distance per interpolation period, which is a unit of time, and interpolates interpolation points on those from the curved path generation unit 204 obtained curve paths. The curve paths that the interpolations have traversed in step S308 form the final curve path. When the generation of the interpolation points is finished, the curve path interpolator gives 210 the interpolation points to the external motor drive unit 211.

With the above machining procedure, the numerical control generates 200 according to the third embodiment the tool path.

The numerical control according to the third embodiment is capable of numerical control in accordance with the changed tool path, so that a machining program does not even need to be converted and then output. Furthermore, the machined workpiece can achieve the desired machining accuracy, so that no post-machining takes place and improved work efficiency is provided.

Fourth embodiment.

A machine learning apparatus according to the fourth embodiment will now be described in detail with reference to the drawings. It should be noted that this embodiment is not restrictive.

30th FIG. 13 shows a configuration example of the machine learning apparatus according to the fourth embodiment. An in 30th shown machining tool 401 machines a workpiece under the control of the numerical control 111 the first embodiment. The numerical control 111 and the editing tool 401 form a numerically controlled machining tool. As in the first embodiment, a converted machining program generated by the machining program converting device 100 is output to the numerical control 111 entered.

The machine learning device 410 According to the present embodiment, uses information indicative of machining accuracy on a result of machining by the machining tool 401 and information obtained from the machining program conversion device 100 are obtained for learning an allowable dimensional tolerance that enables a result of the machining by the machining tool 401 achieved the desired machining accuracy. The allowable dimensional tolerance is an allowable range for the distance L. As described in the first embodiment, the distance L is a distance between an evaluation point on a curved path and a reference point. The reference point is a contact point between a tool and a machining curve surface that corresponds to a final shape of the workpiece. The evaluation point is for determining whether the tool is moving along the machining curve surface when following the curve path that follows between a plurality of command points on a tool path. The result of editing by the editing tool 401 is a result of machining based on the machining program whose tool path has been changed so that the distance L is within the allowable dimensional tolerance.

The machining program conversion device 100 In the present embodiment, the machining curve surface that corresponds to the final shape for the workpiece gives the tool path created by the machining program is determined, in which movement commands for the tool are described, and tool data to the device for machine learning 410 out. The machining program conversion device 100 received from the machine learning device 410 also an allowable dimensional tolerance determined by inference using a learned model generated by machine learning (described below), and the curved path evaluation unit 108 makes determinations using the obtained allowable dimensional tolerance as input. The machining program conversion device 100 is thus in the input and output in connection with the machine learning device 410 of the present embodiment, otherwise this machining program converting device operates 100 like the machining program converting device 100 according to the first embodiment. Constituent elements having the same functions as in the first embodiment have the same reference numerals as in the first embodiment and are not described in order to avoid redundancy. The following description is mainly focused on the differences from the first embodiment.

The machine learning device 410 learns the permissible dimensional tolerance that enables the desired machining accuracy to be achieved. Here, learning the allowable dimensional tolerance that enables the desired accuracy to be achieved means generating the learned model for inferring the allowable dimensional tolerance that enables the desired machining accuracy to be achieved. The machine learning device 410 can use any learning algorithm. An example using reinforcement learning is described below. Reinforcement learning takes place in such a way that an agent (subject of actions) observes a current state in a certain environment and determines an action to be taken. In reinforcement learning, the agent chooses the action and receives a reward from the environment. Through a series of actions, the agent learns a strategy that will maximize the reward. For example, in Q-learning, a general update equation (action value table) is used for an action value function Q (s, a) expressed by the formula (1) below.

$$\text{Q}\left(s_t,a_t\right)\leftarrow Q\left(s_t,a_t\right)+\alpha \left(r_{t+1}+\gamma maxQ\left(s_{t+\mathrm{1,}a}\right)-Q\left(s_t,a_t\right)\right)$$

In the formula (1), t represents an environment at time t, and a _t represents an action at time t. The action a _t causes an environment s _{t + 1 to be moved} . r _{t + 1} represents a reward obtained as a result of shifting this environment, γ represents a discount factor, and α represents a learning rate. For γ, 0 <γ≤1 applies. For α, 0 <α≤1 applies. When Q learning is used in the present embodiment, the action a _{t is} related to the allowable dimensional tolerance that is entered.

The update equation expressed by the formula (1) increases the action value Q when an action value of the best action a is larger than an action value at a time t + 1 Q of the action a, which is taken at time t, and lowers the action value Q if the opposite is true. The action value function Q In other words, (s, a) is updated so that the action value Q of action a at time t approximates the action with the best value at time t + 1. This enables the value of the best action in a given environment to be propagated in turn to action values in previous environments.

As in 30th shown comprises the machine learning apparatus 410 according to the present embodiment, a state observation unit 411 , a learning unit 412 and an inference unit 413 . The condition observation unit 411 is a data acquisition unit that receives a data record including a state variable indicating a state of machining by the numerically controlled machining tool. The condition monitoring unit gives in a learning phase 411 the data record to the learning unit 412 out. The state observation unit gives in an inference phase 411 the data set to the inference unit 413 further. The learning unit 412 generates the learned model by learning, using the data set, the allowable dimensional tolerance that enables the desired machining accuracy to be achieved, and it outputs the learned model to the inference unit 413 further. The inference unit 413 inputs the state variable and other state variables into the learned model, thus inferring the permissible dimensional tolerance that enables the machining accuracy to be achieved. The inferred dimensional allowable tolerance is set in the machining program converting device 100 entered.

In particular, information indicating the final shape for the workpiece and thereby serving as the state variable is provided by the state observation unit 411 from the shape data input unit 106 the machining program conversion device 100 receive. As described in the first embodiment, it is the shape data input unit 106 where the information that the creation of the final shape that the workpiece is to achieve is entered, and the final shape includes the Machining curve surface, which is a curved surface to be machined. This means that information indicating the machining curve surface is included in the information indicating the final shape.

By serving as a state variable, the tool path becomes through the state observer 411 from the tool path storage unit 103 the machining program conversion device 100 receive. As described in the first embodiment, the tool path is determined by the machining program where the movement commands for the tool are described. The condition observation unit 411 also receives the tool data from the tool data input unit 105 the machining program conversion device 100 .

The condition observation unit 411 maintains the machining accuracy in the workpiece produced by the machining tool 401 under the control of the numerical control 111 is elaborated as the state variable based on the converted machining program, which means that the machining accuracy in the result of machining is based on the converted machining program. For example, a value for the machining accuracy measured by an apparatus such as a coordinate measuring machine, a surface roughness measuring machine, or an image size measuring machine can be used. Such a measuring device is for the machining tool 410 in 30th provided, but can also be separate from the machining tool 401 be provided.

In the learning phase, the condition monitoring unit receives 411 from the input unit for the permissible dimensional tolerances 107 the machining program conversion device 100 the allowable dimensional tolerance, which relates to the action in reinforcement learning, and gives this allowable dimensional tolerance to the learning unit 412 further.

The learning unit 412 received from the condition monitoring unit 411 the state variable generated by the state observation unit 411 namely, the machining curve surface corresponding to the final shape of the workpiece, the tool path determined by the machining program, the tool data and the machining accuracy in the result of machining based on the converted machining program. The learning unit learns in accordance with the data set generated based on the state variables 412 the best allowable dimensional tolerance that allows the machining accuracy to be achieved. In the present (fourth) embodiment, the best allowable dimensional tolerance that enables the machining accuracy to be achieved is learned as an example; however, this permissible dimensional tolerance is not restrictive. An allowable dimensional tolerance to be learned can be what a user desires.

As in 30th shown includes the learning unit 412 a reward calculation unit 421 and a function update unit 422 . The reward calculation unit 421 calculates the reward based on the state variable. The reward r is determined by the reward calculating unit 421 calculated based on the machining accuracy in the result of machining based on the converted machining program. The reward calculation unit 421 increases the reward r when, for example, the machining accuracy in the result of machining based on the converted machining program is better than the desired machining accuracy. For example, there is the reward calculation unit 421 “1” as a reward when the machining accuracy in the result of machining based on the converted machining program is better than the desired machining accuracy. On the other hand, when the machining accuracy in the result of machining based on the converted machining program is inferior to the desired machining accuracy, the reward r is lowered. For example, there is the reward calculation unit 421 “-1” as a reward when the machining accuracy in the result of machining based on the converted machining program is worse than the desired machining accuracy. The machining accuracy in the result of machining based on the converted machining program is extracted in accordance with a known method. For example, the machining accuracy in the result of machining can be calculated based on a design value of the workpiece and the value determined by measuring the machined workpiece using the device such as the coordinate measuring machine, the surface roughness measuring device, or the image size measuring device.

In accordance with that provided by the reward calculation unit 421 The function update unit updates the calculated reward 422 the function of determining the allowable dimensional tolerance that enables the result of the machining based on the converted machining program to reach the machining accuracy. In Q-learning, for example, the action value function Q (s _t , a _t ) expressed by the formula (1) as the function for Calculating the allowable dimensional tolerance that enables the machining to achieve the machining accuracy based on the converted machining program is used. In the learning phase, the reward calculation is carried out by the reward calculation unit 421 and the function update by the function update unit 422 performed repeatedly to the learned model, namely the function having a value of Q for s _t and a _t indicates to generate.

The inference unit 413 uses the learned model developed by the functional update unit 422 was generated, and the state variables that were generated by the state observation unit 411 were observed to determine the action a _t for which the action value function Q (s _t , a _t ) increases, namely the allowable dimensional tolerance. The learning unit 412 can learn at the same time to which the inference unit 413 inferred. The learning model can also be used when machining a workpiece of a similar shape. This enables an allowable dimensional tolerance to be determined, which enables a result of the machining of the similar shape to achieve the machining accuracy in a shorter learning period.

The present embodiment has been described using reinforcement learning for the learning algorithm implemented by the learning unit 412 is used; however, this learning is not limiting. As an alternative to reinforcement learning, supervised learning, unsupervised learning or semi-supervised learning can be used for the learning algorithm. For example, when the supervised learning is used, a data set including input data and correct answer data are used as teacher data for creating a learning model. The input data include the above-mentioned information indicating the final shape for the workpiece, the tool path, the tool data and the information indicating whether or not the machining result has achieved the desired machining accuracy. The correct answer data is the allowable dimensional tolerance that is entered. Then, by entering the information indicating the final shape of the workpiece, the tool path, the tool data and the result, which determines that the machining result meets the desired machining accuracy, in the learning model, the permissible dimensional tolerance can be determined, which enables that the desired machining accuracy is achieved.

The learning algorithm described above can also use deep learning, which learns to extract a feature quantity itself, or machine learning can be carried out in accordance with another known method such as a neural network, genetic programming, functional logic programming, or support Vector machine.

The machine learning device 410 can from the machining program conversion device 100 be provided separately, as shown in 30th or it may be in the machining program converting device 100 be included. Another alternative is that the machine learning device 410 in numerical control 111 is included. The machine learning device 410 can be implemented by one or more computers, or it can reside on a cloud server.

The machine learning device 410 may learn the allowable dimensional tolerance that enables the desired machining accuracy to be achieved based on data sets including state variables and actions generated by a plurality of machining program conversion devices 100 can be obtained. The machine learning device 410 can learn the allowable dimensional tolerance that enables the desired machining accuracy to be achieved by using data sets from a variety of machining program conversion devices 100 which are used in a same place or by collecting records from a plurality of machining program converting devices 100 and a plurality of processing devices 401 who work independently in different locations. The machining program conversion device 100 from which the data set is to be collected can be added or, vice versa, removed in the middle of a process. The learned model that the machine learning device 410 by learning for the machining program converting device 100 has generated the allowable dimensional tolerance that enables the desired machining accuracy to be achieved in another machine learning device 410 that of another machining program converting device 100 corresponds to it of the other machine learning device 410 to enable the learned model to be updated by re-learning (relearning) using the newly obtained data set.

In the example described above, the machine learning device receives 410 the data record from the machining program converting device 100 according to the first embodiment; however, the record from the Machining program conversion device 100 according to the second embodiment or the numerical control 200 can be obtained according to the third embodiment. The machine learning device 410 can in numerical control 200 be included according to the third embodiment.

In the fourth embodiment described above, the machining accuracy is determined in the result of machining based on the converted machining program as the state variable by the state observation unit 411 the machine learning device 410 receive. However, the machining accuracy does not have to be the machining accuracy in the result of machining based on the converted machining program. For example, the machining accuracy can be used in a result of machining based on a machining program before conversion. Assume that the machining accuracy is a result of machining a workpiece with the machining tool 401 is, a data set can be generated using this machining accuracy, in combination with the machining curve surface, tool path and tool data described above. This enables the generation of a learning model that can be used for the inference of an allowable dimensional tolerance that enables the desired machining accuracy to be achieved.

The present embodiment described above enables the allowable dimensional tolerance to be automatically determined, which enables the result of the machining to achieve the desired machining accuracy based on the converted machining program. Since the allowable dimensional tolerance is determined in a shortened time as compared with the case where, for example, a worker calculates an appropriate allowable dimensional tolerance, improved work efficiency is provided.

List of reference symbols

100

Machining program conversion device;

101, 201

Machining program input unit;

102, 202

Machining program analyzer;

103, 203

Tool path storage unit;

104, 204

Curve path generation unit;

105, 205

Tool data input unit;

106, 206

Shape data input unit;

107, 207

Input unit for permissible dimensional tolerances;

108, 208

Curve path evaluation unit;

109, 209

Tool path changing unit;

110

Output unit for converted machining program;

111, 200

numerical control;

210

Curve path interpolator;

401

Machining tool;

410

Machine learning device;

411

Condition monitoring unit;

412

Learning unit;

413

Inference unit;

421

Reward calculation unit;

422

Function update unit;

P1 to P6, P11 to P17, R1

Command point;

Q1 to Q

Evaluation point;

C1 to C3, C11 to C13, C21 to C23

Reference point;

L1 to L3, L11 to L13, L21 to L23

Distance;

S1 to S3

Machining curve surface;

T10 to T12

Tool;

TP1 to TP

Curve path.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• JP 2011096077 [0007]

Claims (15)

A machining program conversion apparatus comprising: a curved path generating unit for generating a curved path between a plurality of command points based on a tool path determined from a machining program, movement commands for a tool being described in the machining program, the plurality of command points being provided on the tool path in accordance with the movement commands; an input unit for allowable dimensional tolerances, where values are entered which define an allowable range for a distance L between an evaluation point on the curve path and a reference point, the evaluation point being provided for determining whether a tool is along a machining curve surface which is a final shape for a workpiece corresponds, moves or not, as it follows the cam path, the reference point being a contact point between the tool and the machining cam surface; a curved path evaluation unit for determining whether or not the distance L is between the values defining the allowable range and inputted to the allowable dimensional tolerance input unit; and a tool path changing unit for, when the distance L is out of the allowable range, shifting the evaluation point deviating from the allowable range until the distance L is within the allowable range, and an evaluation point that is moved as a new command point when changing the tool path. The machining program conversion apparatus according to Claim 1 , wherein the curve path generating unit generates a curve path from a first, a second and a third command point which are provided successively, which connects the first command point and the third command point, and wherein the tool path changing unit deletes the second command point when a tool is within the permissible range lying distance L moves along the curved path that connects the first command point and the third command point. The machining program conversion apparatus according to Claim 1 or 2 , further comprising: a tool data input unit where data defining the tool is input; and a shape data input unit where shape data defining the machining curve surface on the workpiece is inputted. The machining program conversion apparatus according to Claim 3 wherein the shape data includes a machining tolerance with respect to the machining curve surface, and the allowable range is determined in accordance with the machining tolerance with respect to the machining curve surface. Numerical control, including: a curved path generating unit for generating a curved path between a plurality of command points based on a tool path determined from a machining program, movement commands for a tool being described in the machining program, the plurality of command points being provided on the tool path in accordance with the movement commands; an input unit for allowable dimensional tolerances, where values are entered which define an allowable range for a distance L between an evaluation point on the curve path and a reference point, the evaluation point being provided for determining whether a tool is along a machining curve surface which is a final shape for a workpiece corresponds to moved when following the cam path, the reference point being a contact point between the tool and the machining cam surface; a curved path evaluation unit for determining whether or not the distance L is between the values defining the allowable range and inputted to the allowable dimensional tolerance input unit; and a tool path changing unit for, when the distance L is out of the allowable range, shifting the evaluation point deviating from the allowable range until the distance L is within the allowable range, and an evaluation point that is moved as a new command point when changing the tool path. Numerical control according to Claim 5 , further comprising a curved path interpolator to determine a tool movement distance per interpolation period and to interpolate an interpolation point on the curved path generated by the curved path generation unit, the interpolation period being a specific period of time. Numerical control according to Claim 5 or 6th wherein the evaluation point deviating from the allowable range for the distance L is shifted by the tool path changing unit until the distance L is within the allowable range and added as a new command point after it is moved. Numerical control according to Claim 5 , wherein the curved path generating unit generates a curved path from a first, a second, and a third command point provided successively, connecting the first command point and the third command point, and wherein the tool path changing unit deletes the second command point when a tool is within the allowable Moved area lying distance L along the curved path that connects the first command point and the third command point. Numerical control according to one of the Claims 5 until 8th , further comprising: a tool data input unit where data defining the tool is input; and a shape data input unit where shape data defining the machining curve surface on the workpiece is inputted. Numerical control according to Claim 9 wherein the shape data includes a machining tolerance with respect to the machining curve surface, and the allowable range is determined in accordance with the machining tolerance with respect to the machining curve surface. A machining program converting method to be executed by a machining program converting device or a numerical controller, the machining program converting method comprising: a step of generating a curved path between a plurality of command points based on a tool path determined from a machining program, movement commands for a tool being described in the machining program, the plurality of command points being provided on the tool path in accordance with the movement commands; a step of inputting values defining a permissible range for a distance L between an evaluation point on the curve path and a reference point, the evaluation point being provided for determining whether a tool is along a machining curve surface which corresponds to a final shape for a workpiece, moves as it follows the curve path, the reference point being a point of contact between the tool and the machining curve surface; a step of determining whether or not the distance L is between the values defining the allowable range and inputted; a step of shifting only the evaluation point that deviates from the allowable range until the distance L is within the allowable range when the distance L is out of the allowable range, and setting an evaluation point that is moved as a new command point at Change the tool path to set; and a step of converting the tool path changed in the step of changing the tool path into a program to be output to an external unit. A machining program converting device according to any one of Claims 1 until 4th further comprising: a data acquisition unit for obtaining a data set containing the machining curve surface, the tool path, tool data defining the tool, and machining accuracy in a result of machining based on a machining program with the tool path changed by the tool path changing unit; and a learning unit for generating, using the data set, a learning model to be used for inference of an allowable range for the distance L that enables the result of machining to achieve a desired machining accuracy. Numerical control according to one of the Claims 5 until 10 further comprising: a data acquisition unit for obtaining a data set containing the machining curve surface, the tool path, tool data defining the tool, and machining accuracy in a result of machining based on a machining program with the tool path changed by the tool path changing unit; and a learning unit for generating, using the data set, a learning model to be used for inference of an allowable range for the distance L that enables the result of machining to achieve a desired machining accuracy. A machine learning apparatus comprising: a data acquisition unit to obtain a data set which corresponds to a machining curve surface which corresponds to a final shape of a workpiece, a tool path which is determined from a machining program in which movement commands for a tool are described, tool data defining the tool and a machining accuracy in a result of the Machining the workpiece comprises; a learning unit for generating, using the data set, a learned model to be used for inference of an allowable range for a distance that enables the result of the machining to achieve a desired machining accuracy. Machine learning apparatus according to Claim 14 , wherein the machining accuracy is the result of machining based on a machining program having the tool path changed so that a distance L between an evaluation point and a reference point is within the allowable dimensional tolerance when the distance L is out of the allowable dimensional tolerance, namely after determining whether or not the distance L is within the allowable dimensional tolerance, the determination being made to see whether the tool is moving along the machining curve surface when following a curve path that is between a plurality of command points on the tool path is generated, the evaluation point being provided on the curve path, the reference point being a contact point between the tool and the machining curve surface, the permissible dimensional tolerance specifying a permissible range for the distance L.

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