JP2003256010A - Control method and control device of machine tool, program of causing computer to execute its control, and computer readable storage media storing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a tool from being damaged due to excessive burden, thereby extending the life of the tool in a machine tool which manufactures a product in a prescribed shape by cutting the work surface of work with the rotatable tool such as a ball end mill. <P>SOLUTION: This control method of the machine tool 4 comprises the steps of calculating the tool path of the tool to the work 2 based on work shape information, product shape information, and tool information, setting a first feed speed when the work 2 is cut by the tool, calculating the contact area of the tool against the work 2 based on the work shape information and the tool information, setting a second feed speed obtained by correcting the first feed speed based on the contact area of the tool against the work 2, and cutting the work 2 by the tool based on the tool path and the second feed speed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a machine tool for cutting a machined surface of a work by a rotating tool to form a product having a predetermined shape, a control device therefor, and a program for causing a computer to execute the control. And a computer-readable recording medium recording the same.

[0002]

2. Description of the Related Art Generally, cutting, for example, NC (numerical control) cutting is carried out by moving a cutting tool so as to follow a predetermined tool path on a work surface of a work (metal material). However, the state of the load applied to the tool may change during the cutting process. For example, in the machining of workpieces with many free-form surfaces such as metal molds for press-molding automobile bodies, ball end mills that enable three-dimensional cutting are mainly used, but the cutting load tends to change frequently. There is.

To solve this problem, conventionally, the load applied to the tool during cutting is detected, and the relative feed speed of the tool is controlled according to the fluctuation of the detected load, whereby the tool is overloaded. Things are being avoided. Further, in Japanese Unexamined Patent Publication No. 61-30355, when a tool is advanced toward a workpiece and contact with the workpiece is detected, adaptive control is started in response to this, and
By reducing the feed rate of the tool at the start,
It is disclosed to avoid damaging the cutting edge of the tool due to overload.

[0004]

By the way, for example, as shown in FIG. 15, a concave portion called a so-called pocket portion 8 is formed on the machined surface of the work 2, and the surface of the pocket portion 8 is formed by the tool 5 (ball end mill). ), The tool 5 moves downward from one open end of the pocket 8 to the bottom, and then moves upward from the bottom toward the other open end. At this time, if the feed rate of the tool 5 is constant,
It is known that the load applied to the tool 5 is larger when the tool 5 moves up as compared to when it moves down.
When the tool 5 is overloaded, the tool 5 is more likely to be damaged, which shortens the life of the tool.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a tool from being damaged by an excessive load applied to it in a machine tool for cutting a work surface of a work by a rotating tool such as a ball end mill to form a product having a predetermined shape. , Thereby extending tool life.

[0006]

SUMMARY OF THE INVENTION The present invention is based on the fact that the contact area of a tool with a work is deeply related to the load applied to the tool. The setting is based on.

Specifically, a machine tool control method of the present invention is for a machine tool that cuts a machined surface of a work with a rotating tool to form a product having a predetermined shape. Based on the shape information and tool information,
Calculating the tool path of the tool for the workpiece,
A step of setting a first feed rate when cutting the work with the tool; a step of calculating a contact area of the tool with the work based on the work shape information and the tool information; Setting a second feed rate that is a correction of the first feed rate based on the contact area of the tool; and cutting the work with the tool based on the tool path and the second feed rate. And are provided.

The contact area of the tool with the work and the load applied to the tool are in a substantially proportional relationship, and observing the contact area means indirectly viewing the load applied to the tool. Therefore, according to the above, the second feed speed, which is the correction of the first feed speed, is set based on the contact area of the tool with respect to the work. Therefore, when the contact area is wide, the first feed speed is By compensating for the lower second feed rate, it is possible to prevent the tool from being damaged by being overloaded, and by doing so, the tool life can be extended.

In the method for controlling a machine tool of the present invention, the second feed rate may be set slower as the contact area of the tool with respect to the work is wider.

With this configuration, the second feed rate corresponds to the contact area of the tool with the workpiece, so that the second feed rate is discontinuously changed and set based on the contact area of the tool. Compared with the above, the action of the present invention is performed more appropriately.

A method of controlling a machine tool according to the present invention is the first method described above.
The feed rate may be set so that the cutting amount per one rotation of one cutting edge of the tool is constant.

The cutting amount per one rotation of the cutting blade of the tool and the cutting load applied to the cutting blade are in a substantially proportional relationship, and it is indirect to see the cutting amount per one rotation of the cutting blade. It means to see the cutting load on the cutting blade.
Therefore, if the cutting amount per one rotation of one cutting blade of the tool is made constant, even if the number of blades or the number of rotations of the tool is changed, the cutting load applied to the tool is not so different. According to the above, the first feed speed is set so that the cutting amount per one rotation of one cutting blade of the tool is constant, so that the cutting blade is set to each cutting blade regardless of the number of blades and the number of rotations. The tool life can be extended by preventing an excessive load from being applied, and the first feed speed becomes faster in a place where the cutting amount is small, for example, in a place where shallow cutting is performed, so that the cutting processing time becomes long as a whole. Can be avoided.

In the machine tool control method according to the present invention, the movement path of the tool from the time when the work comes into contact with the time when the work leaves the work is divided into a plurality of sections, and each is based on the work shape information and the tool information. Obtain the tool peripheral speed at the position of the longest contact length in the radial direction of rotation of the contact portion of the tool with respect to the work when the tool is rotated at a constant number of rotations in a section, and then determine a predetermined plurality of An average tool peripheral velocity that is the average of the tool peripheral velocities of the sections, and a contact high probability position that is the position in the rotational radial direction with the highest contact probability of the tool with respect to the work are obtained, and then the average at the contact high probability position. The method may further include a step of calculating the rotation speed of the tool at the first feed speed so as to obtain the tool peripheral speed.

With a tool such as a ball end mill, even if the tool is rotated at a constant rotational speed, the peripheral speed varies depending on the position in the radial direction of rotation, so the cutting state varies depending on the contact position of the tool with respect to the work. However, according to the above, the averaged rotation speed of the tool corresponding to the contact position of the tool with respect to the work is set, so that the cutting state can be made uniform.

In this case, in the machine tool control method of the present invention, it is preferable that the rotational speed of the tool at the first feed speed is set and changed when the tool is changed. When the rotational speed of the tool is changed during cutting, a step may occur on the processing surface. However, according to the above, the setting of the rotational speed of the tool is changed at the time of changing the tool, so that such a step is not formed on the processing surface.

A control device for a machine tool of the present invention capable of executing the above control method is a machine tool for cutting a machined surface of a work by a rotating tool to form a product having a predetermined shape. Based on the work shape information, the product shape information, and the tool information, a process path calculating means for calculating a tool path of the tool with respect to the work, and a first feed for setting a first feed speed when cutting the work with the tool. The speed setting means, the contact area calculating means for calculating the contact area of the tool with the work based on the work shape information and the tool information, and the first contact area based on the contact area of the tool with the work. Cutting the workpiece with the tool based on the second feed rate setting means for setting the second feed rate in which the feed rate is corrected, and the tool path and the second feed rate. Characterized in that it comprises a cutting execution means, a to.

Of the above control methods, a program for causing a computer to control the machine tool of the present invention for executing the setting of the second feed rate is a product having a predetermined shape by cutting a work surface of a work with a rotating tool. And a step of calculating a tool path of the tool with respect to the work based on the work shape information, the product shape information, and the tool information, and when cutting the work with the tool. Of setting the first feed speed of
Based on the work shape information and the tool information, a procedure for calculating the contact area of the tool to the work,
And a step of setting a second feed rate obtained by correcting the first feed rate based on a contact area of the tool with respect to the work.

A computer-readable recording medium of the present invention is characterized by recording the above program. Such a recording medium is, for example, a flexible disk or a CD-ROM.

[0019]

As described above, according to the present invention,
When the contact area of the tool with the work is large, by compensating the first feed speed with the second feed speed, it is possible to prevent the tool from being damaged due to excessive load, and also to improve the tool life. It can be postponed.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall construction of an NC machine tool 4 for cutting a machined surface of a work 2 to manufacture a die, which is a product, and its control device.

The control device comprises a CAD (computer-aided design) system 1 and a CAM (computer-aided production) system 3. CAD system 1
Is for creating shape data (work shape information, product shape information) from the model of the work 2 and the mold which is the product. The CAM (Computer Aided Manufacturing) system 3
The shape data created by the CAD system 1 is imported, the tool path is calculated, CL (cutter location) data is created, CL data is converted into NC data, and the tool feed speed F is based on the NC data and work material shape information. Settings, instruction sheet creation, process route calculation means,
The first feeding speed setting means, the contact area calculating means, the second feeding speed setting means, and the cutting executing means are configured.

The NC machine tool 4 receives an instruction from the CAM system 3 and cuts the work 2 with a ball end mill.

FIG. 2 shows a processing flow in the CAM system 3.

In step S1 after the start, CAD data is fetched and the tool path of the tool is calculated.

In the following step S2, the tool paths for roughing, finishing and small diameter tool are edited by the editing means.

In the following step S3, the tools for roughing, finishing and small diameter are moved on the screen of the display,
Check the presence or absence of interference of each spindle and edit the edited data again.

In the subsequent step S4, the edited data is converted into a format suitable for the control device and the NC machine tool 4 to create the NC data. Note that step S
As the pre-processing of 4, for example, the approach to the machining position of each tool is set, the cutting order of the tool path of the tool is set (a tool with a short tool length has priority, and a place where the same tool can be used has priority). Set the machining conditions and pick feed (a tool path between the machining areas, and no cutting is performed) height, cut so as not to do unnecessary movement of the tool, from the CL file The number of tools to be used is calculated by looking at the cutting distance, the tool replacement position is set, and the information necessary for creating the instruction sheet is listed from the CL file.

In the following step S5, the tool feed speed F is set by simulation based on the NC data and the work material shape information. And information about the tool to be used, information such as cutting order, etc.
And an instruction sheet is created based on the information after the NC data conversion.

Tool feed rate F in the control of step S5
Is set by using a data processing program that performs the following processing in the CAM system 3.
The processing program is provided by being recorded in a computer-readable recording medium (flexible disk, CD-ROM, etc.). The contents of the processing program will be described in detail below with reference to the flowcharts shown in FIGS.

In step A1 after the start, the NC data file is opened and NC data (tool information such as the standard rotation speed S of the tool) is extracted.

In the following step A2, the material of the predetermined reference, the cutting amount VB per cutting edge in the L / D (tool protruding length / diameter) of the tool to be used is compared with the work 2 Material, coefficient V1 for hardness and L / D of tool
With respect to the coefficient V2 corresponding to the tool to be used among the several kinds of coefficients determined stepwise, the cutting amount V (= VB × V1 × V2) per rotation of one cutting edge of the tool, hereinafter, designated volume or setting 1 Calculate the blade volume V). The predetermined cutting amount VB and the coefficients V1 and V2 are set to optimal values from the viewpoint of tool life and machining time.

At the following step A3, the NC data file is opened to read all the NC data, and the process proceeds to the following step A4.

At step A4, a designated code indicating that the read NC data is coordinate data (for example, straight line approximation code G1, circular interpolation codes G2, G3, NUR).
It is determined whether or not it is the BS interpolation code G6.2),
If it is NC data such as a comment that is not the designated code, it is written as it is (step A32 described later), only the coordinate data that is the designated code is extracted, and the process proceeds to step A5. Here, the NC data, which is the designated code, is the coordinate data of the constituent points (● in the same figure) illustrated in FIG. 5, and one pair of mutually adjacent one constituent points constitutes one tool path. In the figure, a ball end mill having a plurality of cutting blades 6 is shown as the tool 5.

In step A5, each tool path constituted by one constituent point is divided into a plurality of sections, so that the tool path from the contact of the tool with the work 2 to the separation thereof is divided into a plurality of sections.

In the following step A6, the tool circumference at the position of the longest contact length in the radial direction of rotation of the contact portion between the tool and the work 2 when the tool is rotated at the standard rotation speed S at each division point. Calculate speed. In particular,
As shown in FIG. 6, in the Z map coordinate system in which the rotation axis of the tool is the Z axis, the peripheral speed at the position of the most Z coordinate value in the contact portion of the tool with the work 2 is the tool peripheral speed.

In the subsequent step A7, the tool peripheral velocity is added to, ie, integrated with, the one up to the previous section point, and the contact length at each position in the radial direction of rotation of the contact portion between the tool and the workpiece 2 is increased. Is also integrated, and the number of division points is counted.

At the subsequent step A8, it is judged whether or not the tool peripheral speeds at all the division points have been calculated. If the calculation at all the division points has not been completed, the procedure returns to step A6 and the tool at the next division point is determined. The peripheral velocity is calculated, and when the calculation at all the division points is completed, the process proceeds to the subsequent step A9.

In step A9, the average tool peripheral speed which is the average of the tool peripheral speeds of all the division points from the contact of the tool to the work 2 to the separation thereof, and the turning radius with the highest contact probability of the tool with the work 2. The maximum probability contact position (the maximum position of the integrated value of the contact position between the tool and the workpiece 2) that is the position in the direction is calculated, and the rotation speed S of the tool when the average tool peripheral speed is reached at the highest probability contact position is calculated. It is calculated as in the first feed speed F of the tool, which will be described later, and the standard rotation speed of the tool is replaced with it. The rotational speed S of the tool is changed and set when the tool is changed, and thus is constant during cutting with the same tool.

In steps A10 to A29, the tool feed speed F is set for each tool path formed between a pair of component points.

In step A10, the tool path is the work 2
It is determined whether or not the tool is vertical to the machining surface and is forward-fed, and if it is the vertical movement section, the process proceeds to step A11 to set the division length for vertical movement, If it is not the vertical movement section, the process proceeds to step A12 and the division length other than the vertical movement is set.

In the following step A13, the tool path is divided into the set lengths. That is, as illustrated in FIG. 7, in the vertical movement section, a short division length is set and P1 is set.
→ P12-1 → P12-2 →… → P2 is divided, and a longer division length is set for sections other than vertical movement, and P1 → P12-1 → P
Divide into two. In the vertical movement section, the number of divisions is increased in order to reduce the feed speed F of the tool.

At steps A14 to A28, the tool feed speed F is set for each of the divided sections of each tool path formed between a pair of constituent points.

At step A14, the shape data of the required range is read from the shape data. Specifically, it is determined whether or not the range (XY coordinates) of the shape data used for calculation exceeds the used memory. If it is over, unnecessary shape data is written out, and as shown in FIG. 8, the shape data of the work material shape is read only as the range of the shape data necessary for calculation. Due to the limitation of the shape data range, it becomes easy to add the element map information to the memory in addition to the header information, and the Z coordinate value can be efficiently extracted.

In the following step A15, an arc or NUR
It is determined whether or not BS (Non-Uniform Rational B-Spline) processing is required, that is, whether it is a section of circular arc interpolation or NURBS interpolation, and if processing of circular arc or NURBS is necessary, proceed to step A16 and specify tolerance. A value divides the interval further. That is, the curve section is approximated by a polygonal line section in which division points are connected by a straight line, and a set of a plurality of straight line sections is obtained to facilitate volume (cutting amount) calculation.

In the following step A17, the machining volume (required cutting amount) X of the divided one section is calculated based on the tool path and the shape data of the material shape. As shown in FIG. 9, in an inclined section where there is a difference in height between the start point and the end point, as shown in FIG. 10, this is divided into steps, and the Z coordinate value of the material shape of each step 7 and the Z coordinate after processing are processed. The difference from the value may be multiplied by the plane area of each step 7, and the sum of them may approximate the machining volume X.

At step A18, the NC data is replaced with the processed shape data. The replaced shape data becomes data for setting the feed rate when the tool path is cut with another tool.

In the subsequent step A19, as shown in FIG. 4, the feed rate (first feed rate) F of the tool is determined so that one cutting edge of the tool has the designated volume V. That is, the calculation formula is F = V × S × E × L / X.

F: Tool feed speed (mm / min) V: Set 1 blade volume (mm ³ ) S: Tool rotation speed (rpm) E: Number of tool blades L: Section length (mm) X: Section Machining volume (mm ³ ) In the subsequent step A20, the contact area of the tool with the work 2 at the start point (configuration point or division point) of the section is calculated, and the feed rate F is corrected based on the contact area (first 2 Feed speed) Replace with F. Here, the correction of the feed speed F is performed by multiplying by a coefficient. As shown in FIG. 11, the coefficient is constant at 1.0 in a predetermined range where the contact area is small, then linearly decreases as the contact area increases, and is about 0.3 in a predetermined range where the contact area is large. It is constant.

In the following step A21, the contact position of the tool with respect to the work 2 at the start point (configuration point or division point) of the section is obtained, and the feed speed F is corrected based on the contact position (third feed speed). Replace with F. Here, the correction of the feed speed F is performed by multiplying by a coefficient. As shown in FIG. 12, the coefficient is 1.0 when the down-cut processing is performed, and is 0.7 to 0.8 when the upper-cut processing is performed, for example. The load applied to the tool is higher in the upper cut processing than in the down cut processing, but this reduces the load applied to the tool during the upper cut processing.

At the subsequent step A22, it is determined whether or not the feed speed F exceeds a predetermined MAX value (maximum value), and if it exceeds, the routine proceeds to step A23, where the feed speed F is replaced with the MAX value. This is the durability of the tool or NC
The feed rate F is limited from the viewpoint of the specifications of the machine tool 4.

In the following step A24, if the section is a vertical movement section, a process of lowering the feed speed F by a predetermined speed is performed. Therefore, in the vertical movement section, the feed speed F is decelerated and corrected at each of the above-mentioned divided positions, so that the feed speed F gradually decreases, so that the tool vertically pierces the machined surface of the workpiece 2 at a high speed. It is possible to avoid damage.

In the following step A25, it is determined whether or not the feed speed F is lower than a predetermined MIN value (minimum value), and if it is lower, the flow proceeds to step A26 to advance the feed speed F.
Is replaced with the MIN value. This is because if the feed speed F is too slow, the NC machine tool 4 may vibrate.

At the subsequent step A27, the feed speed F is corrected and replaced according to the relation with the feed speed F given to the immediately preceding section. That is, as shown in FIG. 13, when the feed rate given to the immediately preceding section P0 → P1 is F0 and the feed rate calculated for the section P1 → P2 is FC, the change rate K = ΔF01 / F0. When (ΔF01 = | F0−FC |) is equal to or greater than the predetermined value Ko, the calculated value FC is given as the feed speed F1 of the section, but when it is smaller than the predetermined value Ko, the feed rate F1 of the section is given. The feed speed F0 of the preceding section is given. This makes the feed rate control complicated,
It is possible to carry out stable processing while avoiding awkward movements of the machine. The predetermined value Ko is increased as the feed speed F0 given for the immediately preceding section P0 → P1 increases. As a result, at a portion with a high feed speed F (a portion with a low cutting load), even if the feed speed F is slightly different from the calculated value, the cutting load does not change so much, so this is ignored, and the feed is rather changed. The fluctuation of the speed F is prevented, which is advantageous for ensuring the stability of processing. On the other hand, at a portion where the feed speed F is low (a portion where the cutting load is high), the feed speed F is finely controlled in accordance with the change in the feed speed F calculated, so that the cutting blade becomes excessively large. The load can be avoided.

In the subsequent step A28, the number of sections is counted to determine whether or not the tool feed speed F has been set in all sections. If the setting in all sections has not been completed, the process returns to step A14, When the tool feed speed F in the section is set and the calculation in all the sections is completed, the process proceeds to the following step A29.

In step A29, as illustrated in FIGS. 14A and 14B, the tool feed speed F set in each section between the pair of constituent points is rounded. In the example illustrated in FIG. 14, the feed rate F1000 mm /
min (hereinafter, unit omitted), 125 at the end point
0, 5 division points in between, from the start point side in order 1040,
1090, 1120, 1150, and 1175 are rounded, and these are rounded so that the feed rate F1000 is at the starting point, the end point is 1250, and the third dividing point from the starting point is 1120. Is set. This prevents a rapid change in the tool feed speed F and controls the tool to operate smoothly.

At step A30, the feed speed F between the pair of constituent points obtained as described above is stored in the memory.

In the following step A31, the number of constituent points is counted to determine whether or not the feed rate F of the tool has been set between all the constituent points. If the setting among all the constituent points has not been completed, the step A31 is executed. Returning to A10, the tool feed speed F between the next constituent points is set, and when the setting between all constituent points is completed, the process proceeds to the following step A32.

In the following step A32, G is added between the constituent points.
A code is added, and NC data including data of the tool feed speed F is written for each G code. At this time, NC data other than the coordinate data from step A4 is also written out.

In the following step A33, the shape data after cutting is written.

In the following step A34, the NC data file is closed, and then the process ends.

With the control method of the NC machine tool 4 as described above, it is possible to perform cutting of a die used for casting a cylinder head of an automobile engine, for example.

According to the control method of the NC machine tool 4 described above, the second feed speed F obtained by correcting the first feed speed F set based on the cutting amount based on the contact area of the tool with the work 2 is corrected. Is set, the feed speed F is reduced when the contact area is large, and it is possible to prevent the tool from being damaged by being overloaded, and to extend the life of the tool. Moreover, in the predetermined range, the feed speed F is set to be slower as the contact area of the tool with the work 2 is wider, so the feed speed F corresponds to the contact area of the tool with the work 2, and the contact of the tool Compared with the case where the feed rate F is discontinuously changed based on the area, the above-mentioned action is properly performed.

Further, the cutting amount per one rotation of the cutting blade of the tool and the cutting load applied to the cutting blade are in a substantially proportional relationship, and it is indirect to see the cutting amount per one rotation of the cutting blade. It means that the cutting load applied to one cutting edge is observed, but according to the above control method, the first amount of the tool before correction is adjusted so that the cutting amount per one rotation of one cutting edge of the tool becomes constant. Since the feed speed F is set, it is possible to prevent the cutting blade from being overloaded regardless of the number of blades and the number of revolutions S, thereby prolonging the tool life, and further, in a place where the cutting amount is small, For example, since the feed speed F becomes faster in a place where the cutting is performed shallowly, it is possible to prevent the cutting processing time from becoming long as a whole.

Further, in the case of a tool such as a ball end mill, even if the tool is rotated at a constant number of revolutions, the peripheral speed varies depending on the position from the rotation axis, so the cutting state varies depending on the contact position of the tool. In the above control method, the rotation speed S of the tool corresponding to the contact position of the tool with respect to the work 2 is set, so that the cutting state can be made uniform.

When the rotational speed S of the tool is changed during cutting, a step may occur on the machining surface. However, in the above control method, the rotational speed S of the tool at the feed speed F is set when the tool is changed. Since it is changed, such a step is not formed on the processed surface.

In the above embodiment, the ball end mill is exemplified as the tool, but the present invention can be applied to other engine mills and other milling or rotating tools.

An experiment conducted for investigating how the load applied to the tool differs depending on the control method of the machine tool will be described below.

(Experimental Method) <Experiment 1> As shown in FIG.
A 0 mm 2-flute ball end mill is used as the tool 5, and the feed speed is controlled to be constant, and a metal work 2 (having a pocket portion 8) having a width of 55 mm and a thickness of 30 mm.
Was cut. The cut amount is 0.5 to 1.0 m
m, and the rotation speed of the tool was 7100 rpm.

<Experiment 2> The work was cut by controlling the feed rate of the tool so that the cutting amount per one rotation of one cutting edge of the tool was constant.

<Experiment 3> The work is cut by controlling the feed rate of the tool so that the cutting amount per one rotation of one cutting edge of the tool is constant and correcting the feed rate based on the contact area of the tool with the work. processed.

(Experimental Results) FIGS. 16 (a) to 16 (c) show the relationship between the time of Experiments 1 to 3 and the cutting force, that is, the load applied to the tool.

According to these figures, when the feed rate of the tool is controlled to be constant, the load applied to the tool is up to 600 N corresponding to the upward movement of the pocket portion. It can be seen that when the cutting amount per revolution of one cutting blade is controlled to be constant, it is reduced to about 300 N or more. This is one of the tools
This is considered to be because the cutting blade is prevented from being overloaded by setting the feed rate of the tool so that the cutting amount per one rotation of the cutting blade is constant.

When the feed rate of the tool is controlled so that the cutting amount per revolution of one cutting edge of the tool is constant, the load applied to the tool becomes a little over 300N in correspondence with the upward movement of the pocket portion. If the feed rate of the tool is controlled so that the cutting amount per one rotation of one cutting edge of the tool is constant and is corrected based on the contact area of the tool with the work, it is about 300 N or less. You can see that it has been reduced to. This is 1 of 1 cutting edge of tool
This is because it is possible to more effectively prevent an excessive load from being applied to the cutting edge by performing correction based on the contact area of the tool with the work in addition to the control that makes the cutting amount per rotation constant. it is conceivable that.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a machine tool control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of processing in the CAM system of the same embodiment.

FIG. 3 is a flowchart showing a part of a processing flow for setting a tool feed speed according to the same embodiment.

FIG. 4 is a flowchart showing the rest of the flow of processing for setting the tool feed speed in the same embodiment.

FIG. 5 is an explanatory diagram showing tools and NC data configuration points of the same embodiment.

FIG. 6 is an explanatory view showing a contact portion of the tool with respect to the work according to the embodiment.

FIG. 7 is an explanatory diagram showing a division mode of a vertical movement section and another movement section of the same embodiment.

FIG. 8 is a diagram showing a part of an area map of the same embodiment.

FIG. 9 is a diagram showing a part of the shape data of the same embodiment.

FIG. 10 is an explanatory diagram of a method of calculating a processing volume (required cutting amount) of the inclined portion of the same embodiment.

FIG. 11 is a graph showing a relationship between a contact area and a coefficient according to the same embodiment.

FIG. 12 is an explanatory diagram showing correction of the feed rate according to the contact position of the tool with respect to the work according to the embodiment.

FIG. 13 is an explanatory diagram of correction of a feed speed F according to the same embodiment.

FIG. 14 is an explanatory diagram showing a process of rounding the feed rate according to the embodiment.

FIG. 15 is an explanatory diagram showing an experimental method in an example and cutting of a work by a conventional tool.

FIG. 16 is a graph showing the experimental results in the examples.

[Explanation of symbols]

1 CAD system 2 work 3 CAM system 4 machine tools 5 tools 6 cutting blades 7 steps 8 pockets

Continued front page    (72) Inventor Yukio Izutsu             3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda             Within the corporation (72) Inventor Mitsuyoshi Nishimoto             3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda             Within the corporation F-term (reference) 5H269 AB01 AB37 BB12 EE01 NN07

Claims (8)

[Claims] 1. A method of controlling a machine tool, wherein a machined surface of a work is cut by a rotating tool to form a product having a predetermined shape, which is based on the work shape information, the product shape information, and the tool information. Calculating the tool path of the tool, setting the first feed rate when cutting the work with the tool, and contacting the tool with the work based on the work shape information and the tool information Based on the tool path and the second feed speed; a step of calculating an area; a step of setting a second feed speed that is a correction of the first feed speed based on a contact area of the tool with respect to the work; And a step of cutting the work with the tool, the method of controlling a machine tool. 2. The method of controlling a machine tool according to claim 1, wherein the second feed speed is set slower as the contact area of the tool with the work is wider. 3. The method for controlling a machine tool according to claim 1, wherein the first feed speed is set so that a cutting amount per one rotation of one cutting blade of the tool is constant. A method for controlling a machine tool characterized by. 4. The method of controlling a machine tool according to claim 1, wherein a moving path of the tool from contacting the work to leaving the work is divided into a plurality of sections. Based on the shape information and the tool information, at the position of the longest contact length in the radial direction of rotation of the contact portion of the tool with respect to the workpiece when the tool is rotated at a constant rotation speed in each section. Obtaining the tool peripheral speed, then an average tool peripheral speed which is an average of the tool peripheral speeds of a plurality of predetermined sections, and a contact high probability position which is a position in the rotation radius direction where the tool has the highest contact probability with respect to the work. And then calculating the rotational speed of the tool at the first feed speed so that the average tool peripheral speed is obtained at the contact high probability position. Method of controlling a work machine. 5. The method of controlling a machine tool according to claim 4, wherein the rotational speed of the tool at the first feed speed is set and changed when the tool is changed. 6. A machine tool control device for cutting a machined surface of a work by a rotating tool to form a product having a predetermined shape, which is based on the work shape information, the product shape information, and the tool information. Based on the process path calculation means for calculating the tool path of the tool, the first feed speed setting means for setting the first feed speed when cutting the work with the tool, and the work shape information and the tool information A contact area calculating means for calculating a contact area of the tool with respect to the work; and a second feed speed for correcting the first feed speed based on a contact area of the tool with respect to the work.
A machine tool control device comprising: a feed speed setting unit; and a cutting execution unit that cuts the workpiece with the tool based on the tool path and the second feed speed. 7. A program for causing a computer to control a machine tool for cutting a machined surface of a work by a rotating tool to form a product having a predetermined shape, the computer including the work shape information, the product shape information, and the tool. Based on the information, the procedure of calculating the tool path of the tool with respect to the work, the procedure of setting the first feed speed when cutting the work with the tool, based on the work shape information and the tool information A step of calculating a contact area of the tool with respect to the work, and a step of setting a second feed rate obtained by correcting the first feed rate based on a contact area of the tool with respect to the work. Characteristic program. 8. A computer-readable recording medium in which the program according to claim 7 is recorded.