JP7094509B1 - Information processing equipment, control programs and information processing methods - Google Patents

Abstract

An object of the present invention is to efficiently grasp the degree of difficulty in generating chatter vibration in a holder. An information processing device (100) includes a compliance calculator (21) that calculates a third compliance for each of a plurality of candidate holders (2), and a maximum compliance gain using the third compliance. and an index calculation unit (22) that [Selection drawing] Fig. 2

Description

The present invention relates to an information processing device, a control program, and an information processing method for processing a series of information related to the resistance to chatter vibration for a holder for holding a tool.

Conventionally, a technique for cutting a work piece by moving a tool such as a square end mill based on NC (Numerical Control) data generated by CAM (Computer Aided Manufacturing) has been known. CAM is software that generates a tool movement path (tool path) based on a CAD (Computer Aided Design) model shape, which is a target shape, tool information of a tool, and machining conditions. NC data is a machining program that shows tool paths and the like.

In actual cutting, chatter vibration occurs depending on the processing conditions and the like. Chatter vibration is abnormal vibration generated during cutting. When chatter vibration occurs, the condition of the machined surface of the work piece may deteriorate and the tool may be abnormally damaged. In addition, when chatter vibration occurs, it is usually necessary to reduce the machining efficiency, which may increase the machining cost and machining time of the work piece. Here, in cutting, the tool is held by the holder. Therefore, if the degree of difficulty in chatter vibration can be efficiently grasped for each of the plurality of candidate holders used for cutting, it is only necessary to select a holder that is preferable in terms of avoiding chatter vibration. Can be processed efficiently with good processing accuracy.

As an example of the technique for grasping the characteristics of the holder such as the difficulty of chatter vibration, the techniques disclosed in Patent Documents 1 and 2 can be mentioned. The technique disclosed in Patent Document 1 uses the static rigidity of the holder / tool assembly, which is a combination of the holder, the tool, and the protrusion amount of the tool, in order to grasp the characteristics of the holder. The technique disclosed in Patent Document 2 uses the static rigidity of touring, which is a combination of a tool and a holder, for grasping the characteristics of the holder. Static rigidity is expressed by the relationship between the static force and the static displacement of the workpiece due to it. Specifically, the static stiffness is the static force divided by the static displacement of the workpiece. An action object is an object on which a static force acts. Static rigidity is usually expressed as the displacement of a place where a predetermined force acts on a work piece with respect to a predetermined force.

Japanese Unexamined Patent Publication No. 2005-161502 Japanese Unexamined Patent Publication No. 2014-73546

However, neither of the techniques disclosed in Patent Documents 1 and 2 grasps the degree of difficulty in causing chatter vibration in the holder. In addition, since these techniques use static rigidity to grasp the characteristics of the holder, the thickest and shortest holder is selected regardless of the shape and material of the tool as long as there is no interference with the work piece of the holder. It is likely to be used for processing. Here, the "tool shape" specifically means the diameter and length of the portion with the cutting edge, the diameter and length of the portion without the cutting edge (for example, the shank portion of the tool), and the tool from the end face of the holder. Refers to the shape of the entire tool, including the length to the tip (protruding length). Since the shape and material of the tool greatly affect the presence and degree of chatter vibration, depending on the shape and material of the tool used, an unfavorable holder is selected from the viewpoint of avoiding chatter vibration, and it is used for actual machining. May be used.

One aspect of the present invention has been made in view of the above-mentioned problems, and an object thereof is to efficiently grasp the degree of difficulty in causing chatter vibration depending on the shape and material of the tool in the holder.

In order to solve the above-mentioned problems, the information processing apparatus according to one aspect of the present invention acquires the first compliance information indicating the compliance of the tool for machining the work piece and holds the tool. A compliance calculation unit and a plurality of compliance calculation units that calculate the compliance of a touring having the holder holding the tool by acquiring the second compliance information indicating the compliance of the holder for each of the plurality of holders. For each of the holders, the compliance of the touring having the holder calculated by the compliance calculation unit is used to indicate the degree of difficulty in causing chatter vibration when the work piece is machined by the tool. It is equipped with an index calculation unit that calculates a stability index.

In order to solve the above-mentioned problems, the information processing method according to one aspect of the present invention is for acquiring the first compliance information indicating the compliance of the tool for machining the work piece and holding the tool. A compliance calculation step for calculating the compliance of a touring having the holder holding the tool for each of the plurality of holders by acquiring the second compliance information indicating the compliance of the holder for each of the plurality of holders, and a plurality of steps. For each of the holders, the degree of difficulty of chatter vibration generated during machining of the work piece by the tool is shown by using the compliance of the touring having the holder calculated in the compliance calculation step. Includes an index calculation step to calculate the chatter stability index.

According to one aspect of the present invention, it is possible to efficiently grasp the degree of difficulty in causing chatter vibration depending on the shape and material of the tool in the holder.

It is a schematic diagram of a work piece and a touring with a specific holder. It is a block diagram which shows an example of the functional structure of the information processing apparatus which concerns on 1st to 3rd Embodiment of this invention. It is a flowchart which shows an example of the specific processing by the information processing apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the model of the candidate holder used for the calculation of the 2nd compliance. It is a figure which shows the model of the rotary tool used for the calculation of the 1st compliance. It is a figure which shows the model of the touring used for the calculation of the 3rd compliance. It is a graph which shows an example of the relationship between a frequency and a compliance gain in the touring which concerns on 1st Embodiment of this invention. It is a graph which shows an example of the chattering stability limit diagram of a rotary tool. It is a graph which shows an example of the relationship between frequency and compliance in the touring which concerns on 1st Embodiment of this invention. It is a flowchart which shows an example of the specific processing of the information processing apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows an example of the feedback loop generated by the information processing apparatus which concerns on 2nd Embodiment in this invention. It is a graph which shows an example of a gain margin. It is a flowchart which shows an example of the specific processing of the information processing apparatus which concerns on 3rd Embodiment of this invention. It is a flowchart which shows an example of the calculation process of the processing error by the information processing apparatus which concerns on 3rd Embodiment of this invention. It is a graph which shows the compliance obtained by the vibration measurement of the 1st to 4th holder which concerns on 1st Example of this invention. It is a graph which shows the compliance of the round bar which imitated the rotary tool which concerns on 1st Embodiment of this invention. It is a graph which shows the estimated compliance of the 1st to 4th touring which concerns on 1st Embodiment of this invention. It is a figure which shows the simulation content of the side surface processing which concerns on 2nd Embodiment of this invention. It is a figure which shows the contour line processing of the inclined surface which concerns on 3rd Embodiment of this invention, and the cutting parameter thereof.

[First Embodiment]
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 1 to 9. In the present embodiment and the second and third embodiments described later, a stationary personal computer will be described as an example of the information processing device according to one aspect of the present invention. The information processing device according to one aspect of the present invention may be, for example, a control device (not shown) or a tablet terminal provided in the machine tool 3 described later.

<Application scene of information processing equipment>
An application scene of the information processing apparatus 100 according to the first embodiment of the present invention will be described with reference to FIG. The information processing apparatus 100 (see FIG. 2) is used when cutting the work piece W as shown in FIG. In the example of FIG. 1, the work piece W is cut by the rotary tool 1 (tool) attached to the machine tool 3. The rotary tool 1 is, for example, a square end mill, and the machine tool 3 is, for example, an NC 3-axis machine tool. The machine tool 3 may be, for example, an NC lathe. In this case, a non-rotating tool such as a cutting tool is attached to the machine tool 3 instead of the rotating tool 1. That is, the tool attached to the machine tool 3 may be either a rotating tool or a non-rotating tool.

Specifically, by attaching the specific holder 2-1 holding the rotary tool 1 to the machine tool 3, the rotation axis (tool axis) of the rotary tool 1 is oriented in the direction of the Z axis shown in FIG. , The rotary tool 1 is attached to the spindle (not shown) of the machine tool 3. The specific holder 2-1 is a holder actually used for cutting the work piece W by the rotary tool 1, and corresponds to the stable holder 2-2 described later. The holder is a part for holding the rotary tool in general, and is a link connecting the rotary tool in general and the spindle of the machine tool 3. The rotary tool 1 and the specific holder 2-1 attached to the machine tool 3 rotate at various rotation speeds by a drive unit (not shown) built in the machine tool 3.

When cutting the work piece W, the work piece W is fixed to the table 7 and the cutting edge 6 of the rotary tool 1 is positioned. Specifically, the vise 5 is installed on the upper surface of the table 7, and the work piece W is fixed to the table 7 by sandwiching the work piece W with the vise 5. The vise 5 is a jig for fixing a work such as a work piece W to the table 7. The positioning of the cutting edge 6 is performed by NC control for the three XYZ orthogonal axes shown in FIG. 1 based on the NC data generated by the CAM installed in the information processing apparatus 100. The NC data includes the movement path information (coordinate values) of the rotary tool 1. By moving the rotary tool 1 based on the NC data, the work piece W is cut by the rotary tool 1.

<Functional configuration of information processing equipment>
The functional configuration of the information processing apparatus 100 will be described with reference to FIG. The information processing device 100 is a device that calculates a chatter stability index described later for each of a plurality of holders prepared in advance. By grasping the chatter stability index, the user of the information processing apparatus 100 can select a holder that is relatively unlikely to cause chatter vibration as the specific holder 2-1 from a plurality of holders prepared in advance. .. Hereinafter, the plurality of holders prepared in advance will be referred to as "plurality of candidate holders 2 (see FIG. 4)". The specific holder 2-1 corresponds to one of a plurality of candidate holders 2. As shown in FIG. 2, the information processing apparatus 100 includes a display unit 11, an operation input unit 12, a storage unit 13, and a control unit 14.

The display unit 11 displays various images generated due to the execution of various functions (application software) included in the information processing apparatus 100 under the control of the control unit 14. The operation input unit 12 acquires the input user operation. If the information processing device 100 is, for example, a tablet terminal, the information processing device 100 may include a touch panel in which the display unit 11 and the operation input unit 12 are integrated. Further, the information processing apparatus 100 does not have to include the display unit 11 and the operation input unit 12. If the information processing device 100 is, for example, a control device provided in the machine tool 3, the operation panel or the like with a display screen in the machine tool 3 has a configuration corresponding to the display unit 11 and the operation input unit 12.

The storage unit 13 stores, for example, various control programs executed by the control unit 14. Further, the storage unit 13 stores, for example, various input data based on the user operation acquired by the operation input unit 12, calculation results of the compliance calculation unit 21 and the index calculation unit 22, which will be described later. The control unit 14 comprehensively controls each unit of the information processing apparatus 100. The control unit 14 includes a compliance calculation unit 21 and an index calculation unit 22.

The compliance calculation unit 21 calculates the first compliance information and acquires the second compliance information. The first compliance information is information indicating the first compliance, which is the compliance of the rotary tool 1. The second compliance is information indicating the second compliance, which is the compliance of the candidate holder 2. Compliance is a transfer function that indicates the vibration characteristics of a structure, and is a frequency response function that is represented by a complex number. Compliance is also the reciprocal of the dynamic stiffness of the structure. The compliance calculation unit 21 acquires the second compliance information for each of the plurality of candidate holders 2. Details of the first and second compliance information will be described later.

The compliance calculation unit 21 calculates the third compliance, which is the compliance of the touring 4, by using the first and second compliance information. The details of the third compliance will be described later. The touring 4 is a structure composed of the rotary tool 1, the candidate holder 2, and the machine tool 3 in a state where the candidate holder 2 holding the rotary tool 1 is attached to the machine tool 3. For example, as shown in FIG. 1, a structure composed of a rotary tool 1, a specific holder 2-1 and a machine tool 3 in a state where the specific holder 2-1 holding the rotary tool 1 is attached to the machine tool 3. Also, it becomes touring 4. By configuring the touring 4 for each candidate holder 2, the compliance calculation unit 21 calculates the third compliance for each of the plurality of candidate holders 2.

The index calculation unit 22 calculates a chatter stability index for each of the plurality of candidate holders 2 by using the third compliance calculated by the compliance calculation unit 21. The chatter stability index is an index showing the degree of difficulty in occurrence of chatter vibration generated during cutting of the work piece W by the rotary tool 1. In the present embodiment, the index calculation unit 22 calculates the maximum value of the compliance gain of the third compliance as the chatter stability index. Compliance gain is the magnitude (amplitude) of compliance.

In the present embodiment, as the chatter vibration that is the target of the chatter stability index, self-excited chatter vibration generated due to the machining process of the work piece W and the vibration characteristics of the touring 4 and the like is assumed. Self-oscillation vibrations are mainly caused by regeneration effects or mode coupling. However, it is also possible to target forced chatter vibration generated by force disturbance or displacement disturbance caused by some kind of forced vibration source, such as intermittent cutting by the rotary tool 1, as the target of the chatter stability index.

<Specific processing of information processing equipment>
An example of specific processing of the information processing apparatus 100 will be described with reference to FIGS. 3 to 9. The series of processes of steps S11 to S15 described below corresponds to the information processing method according to one aspect of the present invention. As shown in FIG. 3, in step S11, the compliance calculation unit 21 acquires the tool information of the rotary tool 1 via the operation input unit 12. The tool information includes information on the diameter of the rotary tool 1, the protrusion length from the tip 2b (details will be described later) of the candidate holder 2, the number of blades, the twist angle, the material, and the like.

When considering the difference in rigidity between the portion with the cutting edge 6 and the portion without the cutting edge 6 (hereinafter, “shank portion”), the diameter and length of the portion with the cutting edge 6 and the diameter of the shank portion. And the shape information of the entire rotary tool 1 such as the length is also included in the tool information. Further, when the portion having the cutting edge 6 and the shank portion have a tapered shape, the information is also included in the tool information.

The compliance calculation unit 21 may acquire the tool information from the operation input unit 12 in which the tool information is input, or may acquire the tool information from the server in which the tool information is stored or the storage unit 13. When the tool information is stored in the server, the information processing apparatus 100 performs wireless (or wired) communication with the server, so that the compliance calculation unit 21 acquires the tool information from the server. When the tool information is stored in the storage unit 13, the compliance calculation unit 21 reads the tool information from the storage unit 13, so that the compliance calculation unit 21 acquires the tool information.

Further, in step S11, the compliance calculation unit 21 acquires the second compliance information for each of the plurality of candidate holders 2. In the present embodiment, the second compliance information is generated in advance, and the second compliance information of the plurality of candidate holders 2 is stored as a holder list in, for example, the server or the storage unit 13. The holder list is a data table in which the candidate holder 2 and the second compliance are associated with each of the plurality of candidate holders 2. The point that the compliance calculation unit 21 may acquire the holder list from the operation input unit 12, the server, or the storage unit 13 is the same as the acquisition of the tool information.

In the present embodiment, the second compliance obtained by vibrating and measuring the candidate holder 2 becomes the second compliance information. The vibration measurement of the candidate holder 2 is performed as follows. First, the candidate holder 2 is attached to the machine tool 3 in a single state (a state in which the rotary tool 1 is not held), and then the candidate holder 2 is vibrated by, for example, an impulse hammer. Then, the response (vibration) of the candidate holder 2 due to the vibration is measured by an acceleration sensor, a laser Doppler vibrometer, or the like. The target for attaching the candidate holder 2 is not limited to the machine tool 3, and for example, a jig for vibration measurement to which the candidate holder 2 can be attached may be used. However, in order to measure the vibration of the candidate holder 2 with high accuracy, it is desirable that the jig for vibration measurement has the same compliance as that of the machine tool 3.

The compliance calculation unit 21 calculates the compliance matrix R _2b2b represented by the following equation (1) as the second compliance by using the measurement result of the vibration measurement. The compliance matrix R _2b2b is a compliance matrix of the candidate holder 2 shown in FIG.

The compliance matrix R _xy represents the response (deflection (displacement) or deflection angle) of the position of x when an input (force or moment) is applied to the position of y. Each component of the compliance matrix R _xy is a transfer function that is a function of frequency (ie, has a different value for each frequency). Specifically, the 1st row / 1st column component of the compliance matrix R _xy is the deflection / force, the 1st row / 2nd column component is the deflection angle / force, the 2nd row / 1st column component is the deflection / moment, and the 2nd row / 2nd column component is. The deflection angle / moment is shown respectively. The 1-row 1-column component is h _2b2b in the above-mentioned formula (1), the 1-row 2-column component is l _2b2b in the above-mentioned formula (1), and the 2-row 1-column component is in the above-mentioned formula (1). The two-row, two-column component corresponds to n _2b2b , respectively, and corresponds to p _2b2b in the above equation (1). The "moment" is a bending moment given to a predetermined position (position of y) of the candidate holder 2. The "deflection angle" is a bending angle when the candidate holder 2 is bent.

The calculation method of the compliance matrix R _2b2b using the measurement result of the vibration measurement is as follows. As shown in FIG. 4, first, the position U _2b on the tip 2b of the candidate holder 2 and the position U ₃ separated from the tip 2b of the candidate holder 2 by a straight line distance S are vibrated. The linear distance S is the shortest distance between the tip 2b and the plane parallel to the tip 2b and including the position U ₃ , and coincides with the shortest distance between the position U _2b and the position U ₃ .

Next, the response (displacement) of the candidate holder 2 due to the input (vibration) at the position U _2b and the response of the candidate holder 2 due to the input at the position U ₃ are measured at the position Q _2b on the tip 2b. As a result, compliance (h _2b2b , h _2b3 ) is obtained. The length of the straight line connecting the position U _2b and the position Q _2b coincides with the outer diameter of the candidate holder 2. Alternatively, compliance is achieved by inputting only to the position U _2b and measuring the response of the candidate holder 2 by the input at the position U _2b at the position Q _2b and the position Q ₃ separated from the tip 2 b by a straight line distance S. (H _2b2b , h _32b ) is obtained. The shortest distance between the position Q _2b and the position Q ₃ coincides with the straight line distance S. The compliance h _2b2b is a component of the compliance matrix R _2b2b as shown in the above equation (1).

Next, by substituting either compliance (h _2b2b , h _2b3 ) or (h _2b2b , h _32b ) into the following equation (2), compliance (l _2b2b , n _2b2b ) which is a component of the compliance matrix R _2b2b ) Is calculated. Then, by substituting the compliance (h _2b2b , n _2b2b ) into the following equation (3), the compliance p _2b2b , which is a component of the compliance matrix R _2b2b , is calculated. In this way, the compliance matrix R _2b2b is calculated.

The method for calculating the compliance matrix R _2b2b is not limited to the above example. For example, the compliance matrix R _2b2b may be calculated by inputting to three places including the position U _2b in the candidate holder 2. Further, for example, the compliance matrix R _2b2b may be calculated by a method of calculating by combining beam models or by CAE (Computer Aided Engineering) analysis such as FEM (Finite Element Method). When the method of calculating the compliance matrix R _2b2b without performing the vibration measurement as described above is adopted, for example, the compliance calculation unit 21 may calculate the compliance matrix R _2b2b .

Further, the timing at which the compliance calculation unit 21 acquires the second compliance information is not limited to the case of step S11, and may be acquired at any timing of step S12 or S13 described later, for example. That is, the compliance calculation unit 21 may acquire the second compliance information at an arbitrary timing before executing the third compliance calculation process.

In step S12, the compliance calculation unit 21 calculates the first compliance using the tool information. Specifically, the compliance calculation unit 21 calculates the compliance matrix _Ra represented by the following equation (4) as the first compliance. In the present embodiment, the compliance matrix _Ra calculated by the compliance calculation unit 21 is the first compliance information.

The compliance matrix R _a is a compliance matrix of the free ends 1 a on both sides of the rotary tool 1 shown in FIG. The compliance matrix R _a is composed of four compliance matrices R _XY (X = Y = 1, 2) obtained by the combination of the inputs U ₁ and U ₂ and the responses Q ₁ and Q ₂ at the free ends 1 a on both sides. do.

In the present embodiment, the compliance calculation unit 21 uses the vibration equation of BE (Bernoulli-Euler) represented by the following equation (5) in addition to the above equation (4) to obtain the compliance matrix R. Calculate _a . That is, the compliance calculation unit 21 calculates the coefficients c1 to c7 shown in Table 1 below by solving the following equation (5) for the boundary condition (x = 0, x = L).

The element x of the boundary condition is the length in the tool axis direction from the end face of the free end 1a in the rotary tool 1, and x = L is the protrusion length from the tip 2b of the candidate holder 2. The value of the protrusion length L is included in the tool information. Actually, one of the free ends 1a on both sides is a fixed end (fixed by the candidate holder 2), but when calculating the compliance matrix Ra, it is calculated as _a free end. Then, the compliance calculation unit 21 substitutes the obtained coefficients c1 to c7 into the equations shown in Table 1 below to calculate the compliance (H _XY , N _XY , L _XY , P _XY ), thereby performing the compliance. Calculate the matrix R _a .

It is not essential to use the vibration equation of BE in the calculation of the compliance matrix _Ra , and instead, for example, Timoshenko beam theory may be used. Further, the compliance calculation unit 21 does not have to calculate the first compliance such as the compliance matrix _Ra . In this case, the compliance calculation unit 21 may acquire the first compliance information from the operation input unit 12, the server, or the storage unit 13.

In step S13, the compliance calculation unit 21 calculates the third compliance using the first and second compliance information for each of the plurality of candidate holders 2. The series of processing steps of steps S11 to S13 correspond to the compliance calculation step according to one aspect of the present invention. Specifically, the compliance calculation unit 21 calculates the compliance matrix G ₁₁ for the candidate holders 2 arbitrarily extracted from the plurality of candidate holders 2 by using the following equation (6), so that the compliance H ₁₁ To get.

The compliance matrix G ₁₁ is a compliance matrix at the tip of the touring 4 shown in FIG. The tip of the touring 4 corresponds to one of the free ends 1a of the rotary tool 1 shown in FIG. 5 (the side that comes into contact with the work piece W during cutting). In the present embodiment, the compliance calculation unit 21 calculates the compliance matrix G ₁₁ by combining the compliance matrix _{Ra representing the first compliance and the compliance matrix R 2b2b representing} the second compliance. In other words, the above-mentioned equation (6) representing the compliance matrix G ₁₁ is calculated from the above-mentioned equation (4) representing the compliance matrix R _a and the above-mentioned equation (1) representing the compliance matrix R _2b2b . ..

The above-mentioned equation (6) is an equation when the joint portion 411 between the rotary tool 1 and the candidate holder 2 in the touring 4 is assumed to be a rigid body. The coupling portion 411 is a boundary between the exposed portion of the rotary tool 1 and the candidate holder 2 in the touring 4. Here, for example, by modeling and incorporating a spring element or a damping element into the coupling portion 411, the above equation (6) takes into account the elasticity or damping of the coupling portion 411.

Next, the compliance calculation unit 21 sets the compliance H ₁₁ obtained by calculating the compliance matrix G ₁₁ as the third compliance. The compliance H ₁₁ is a component of the compliance matrix G ₁₁ and is a compliance representing a displacement with respect to a force at the tip of the touring 4 (one of the free ends 1a of the rotary tool 1). The compliance calculation unit 21 outputs the calculated third compliance (specifically, compliance H ₁₁ ) to the index calculation unit 22.

The touring 4 to be calculated for the third compliance does not have to include the machine tool 3 as a component. For example, in the vibration measurement of the candidate holder 2 which is the premise of the calculation of the compliance matrix R _2b2b , when the candidate holder 2 is attached to the vibration measurement jig, the jig is replaced with the machine tool 3 in the touring 4. Become an element. That is, the touring to be calculated for the third compliance is not limited to the touring 4 including the machine tool 3 as a component, and may include at least the rotary tool 1 and the candidate holder 2 as components.

Further, the third compliance is not limited to the compliance representing the displacement of the touring 4 with respect to the force. As the third compliance, the compliance calculation unit 21 may calculate, for example, the compliance representing the displacement of the touring 4 with respect to the moment.

In step S14, the index calculation unit 22 calculates the maximum value of the compliance gain (hereinafter, abbreviated as “compliance gain”) of the third compliance acquired from the compliance calculation unit 21. Step S14 corresponds to the index calculation step according to one aspect of the present invention. Specifically, the index calculation unit 22 calculates the compliance gain for each frequency using the following equations (7) and (8), and then identifies the one with the largest value from these compliance gains. .. The third compliance is expressed by the following formula (7), and the compliance gain is calculated from the following formula (8).

An example of the calculation result of the index calculation unit 22 is shown in the graph of FIG. Further, FIG. 8 shows an example of the chattering stability limit diagram of the rotary tool 1. The chatter stability limit diagram shows a boundary line (stability limit) that is a boundary of the presence or absence of chatter vibration in a two-dimensional map composed of a rotation speed and a depth of cut. The chatter stability limit diagram shown in FIG. 8 assumes that the radial depth of cut of the rotary tool 1 is constant, and the depth of cut in the tool axial direction (“axial depth of cut” in FIG. 8). The limit depth of cut in is shown as the above-mentioned boundary line. The minimum value of the limit cut amount is called the unconditional stable limit cut amount.

In the touring 4 whose calculation result is illustrated in FIG. 7, the compliance gain becomes maximum when the frequency is about 2800 Hz. Further, in the example of FIG. 8, the unconditional stability limit depth of cut of the rotary tool 1 is about 6 mm. Here, the maximum value of the compliance gain greatly affects the unconditional stability limit depth of cut of the rotary tool 1. Specifically, the smaller the maximum value of the compliance gain, the larger the unconditional stability limit depth of cut of the rotary tool 1. This means that the smaller the maximum value of the compliance gain, the less likely it is that chatter vibration will occur. For example, if the maximum value of the compliance gain of one touring is half that of another touring, the other touring will cause chatter vibration at the stage where the cut amount that causes chatter vibration in one touring is approximately doubled. ..

From this, by calculating the maximum value of the compliance gain for each of the plurality of candidate holders 2 and comparing the magnitudes of those values, the candidates from among the plurality of candidate holders 2 are relatively unlikely to generate chatter vibration. Holder 2 can be selected as the specific holder 2-1.

It should be noted that, for example, standard constant cutting conditions are set for each diameter of the rotary tool 1 or for each machining pattern (roughing, intermediate finishing, finishing; hereinafter abbreviated as "machining pattern") of the diameter of the rotary tool 1. Suppose. In this case, a reference value for determining whether or not a certain candidate holder 2 corresponds to the specific holder 2-1 can be set for each diameter of the rotary tool 1 or for each machining pattern. This reference value is the minimum value when the maximum value of compliance indicates a value at which the degree of resistance to chatter vibration is equal to or higher than the permissible level.

Therefore, for example, a database in which the cutting conditions and the above-mentioned reference values are associated with each diameter or machining pattern of the rotary tool 1 is stored in the server or the storage unit 13, and the control unit 14 acquires the database. It becomes possible to select a specific holder 2-1. Specifically, the operation input unit 12 and the like receive the machining pattern, and the control unit 14 reads out the reference value associated with the corresponding machining pattern from the database. Then, if the maximum value of compliance calculated by the index calculation unit 22 is equal to or greater than the read reference value, the control unit 14 selects the candidate holder 2 to be calculated by the index calculation unit 22 as the specific holder 2-1. ..

In step S15, the index calculation unit 22 determines whether or not the maximum value of compliance has been calculated for all of the plurality of candidate holders 2. If Yes in step S15, the series of processes of steps S11 to S15 by the information processing apparatus 100 is completed. The calculation result of the compliance calculation unit 21 and the calculation result of the index calculation unit 22 at the time when the series of processing by the information processing apparatus 100 is completed are stored in the server or the storage unit 13 in a state of being incorporated in the holder list, for example. You may. Further, for example, these calculation results may be displayed on the display unit 11. On the other hand, if No in step S15, the information processing apparatus 100 executes the processes of steps S13 to S15 again.

<Modification example>
The index calculation unit 22 may calculate the minimum value of the real part or the minimum value of the imaginary part in the third compliance as the chatter stability index. The real part of the third compliance (hereinafter, abbreviated as “real part”) corresponds to “Real” in the above-mentioned equations (7) and (8). The imaginary part of the third compliance (hereinafter, abbreviated as "imaginary part") corresponds to "Imag" in these formulas.

An example of the calculation result when the index calculation unit 22 calculates the minimum value of the real part and the minimum value of the imaginary part as the chatter stability index is shown in the graph of FIG. In the touring 4 whose calculation result is illustrated in FIG. 9, the real part becomes the minimum (negative value) when the frequency of chatter vibration is about 2850 Hz. Further, when the frequency of chatter vibration is about 2800 Hz, the imaginary portion becomes the minimum (negative value).

The closer the minimum value of the real part is to 0, in other words, the smaller the absolute value of the minimum value of the real part, the more likely that the candidate holder 2 to be calculated corresponds to a holder in which chatter vibration is relatively unlikely to occur. Is high. When chatter vibration occurs in one direction, such as when the depth of cut in the radial direction is small, it is effective to use the minimum value of the real part as the chatter stability index. The closer the minimum value of the imaginary part is to 0, in other words, the smaller the absolute value of the minimum value of the imaginary part, the more likely that the candidate holder 2 to be calculated corresponds to a holder in which chatter vibration is relatively unlikely to occur. Is high. When the compliance in both XY directions is the same as in an end mill and the depth of cut in the radial direction is large, it is effective to use the minimum value of the imaginary portion as a chattering stability index.

<Summary>
By acquiring the first and second compliance information, the information processing apparatus 100 calculates the stability index (the maximum value of the compliance gain in the present embodiment) in consideration of the third compliance. Therefore, for example, when the information processing apparatus 100 displays the chatter stability index of the plurality of candidate holders 2 on the display unit 11, the plurality of candidate holders 2 are less likely to cause chatter vibration based on the display contents of the display unit 11. It can be ranked in descending order of degree. As a result, the candidate holder 2 that is relatively unlikely to cause chatter vibration can be easily selected.

The information processing apparatus 100 calculates the maximum value of the compliance gain as a chatter stability index. Here, as described above, it has been found that the smaller the maximum value of the compliance gain is, the less likely the chatter vibration is to occur. Therefore, by selecting the candidate holder 2 having the smaller maximum value of the compliance gain from the plurality of candidate holders 2, the candidate holder 2 that is relatively unlikely to cause chatter vibration can be selected without calculating the stability limit. ..

The touring 4 to be calculated for the third compliance has a machine tool 3 as a component, and has the same touring configuration as when the work piece W is actually cut. As a result, the information processing apparatus 100 can calculate the third compliance that is closer to the actually measured value, and can calculate the maximum value of the compliance gain with high accuracy.

[Second Embodiment]
A second embodiment of the present invention will be described below. For convenience of explanation, the same reference numerals are given to the members having the same functions as the members described in the first embodiment, and the description thereof will not be repeated. This also applies to the third embodiment described later. The information processing apparatus 200 according to the second embodiment of the present invention is different from the information processing apparatus 100 according to the first embodiment of the present invention in that the control unit 14 includes the holder selection unit 23 shown in FIG. .. The information processing device 200 is also different from the information processing device 100 in that the index calculation unit 22 calculates the chatter stability as a chatter stability index.

<Specific processing of information processing equipment>
An example of specific processing of the information processing apparatus 200 will be described with reference to FIGS. 10 to 12. Each process of steps S21 to S23 in the flowchart of FIG. 10 is the same as each process of steps S11 to S13 in the flowchart of FIG.

As shown in FIG. 10, in step S24, the index calculation unit 22 acquires cutting parameters (machining parameters) constituting the cutting conditions. The cutting parameters include (i) rotation speed of the work piece W, (ii) radial and tool axial depth of cut, (i) in the case of rotary tool 1 or turning (working in which the work piece W rotates). iii) Feed speed, cutting force coefficient, NC data, etc. can be mentioned. The cutting force coefficient, also called specific cutting resistance, indicates the relationship between the cutting thickness of the cutting edge 6 (see FIG. 1) of the rotary tool 1 and the cutting force (details will be described later). The index calculation unit 22 may acquire these cutting parameters from the operation input unit 12, or may acquire them from the server or the storage unit 13.

Next, the index calculation unit 22 calculates the process gain 31 shown in FIG. 11 for the candidate holders 2 arbitrarily extracted from the plurality of candidate holders 2 using the cutting parameters. The process gain 31 represents the relationship between the vibration displacement ( _Δx , _Δy ) of the rotary tool 1 and the amount of change in the cutting force (Fx, Fy) generated by the vibration displacement, and specifically, the unit vibration displacement. It is the amount of change in the cutting force per hit. The vibration displacement is the difference between the current vibration displacement (x (t), y (t)) and the vibration displacement one blade before (x (tT), y (tT)).

Next, the index calculation unit 22 generates the feedback loop 30 shown in FIG. 11 for the candidate holder 2 for which the process gain 31 has been calculated, using the third compliance calculated by the compliance calculation unit 21 in step S23. Here, _Gxx in FIG. 11 is the third compliance indicating the response in the x direction when inputting in the x direction, and G _yy in FIG. 11 indicates the response in the y direction when inputting in the y direction. The third compliance. Each of G _xx and G _yy may be calculated, and when the rotary tool 1 is a cylindrical isotropic tool such as an end mill, only one direction (for example, G _yy in the Y direction) is calculated, and G _xx is simply calculated. = G _y may be set. It should be noted that each of G _xy and G _yx may be calculated, or G _xy = G _yx = 0 may be simply set.

The feedback loop 30 is generated for the machining process of the work piece W by the rotary tool 1, and has a process gain 31 and a third compliance (specifically, compliance H ₁₁ : see the above equation (6)) and time. It is composed of a delay element 32. The time delay element 32 is an element representing a state immediately before the state currently being machined (for example, one rotation before and one blade before). In the equation e- ^iωT of the time delay element 32 shown in FIG. 11, ω is an angular frequency. T is the time difference between the state currently being machined and the state one blade before, and is calculated from the rotation speed and the number of blades of the rotary tool 1.

In the present embodiment, the index calculation unit 22 calculates the one-round transfer function D represented by the following equation (9) in order to evaluate the stability of the feedback loop 30 as shown in FIG. In the following formula (9), a is the axial depth of cut of the work piece W by the rotary tool 1. K _t is a coefficient in the main component direction of the cutting force coefficient. a _XX is a matrix of cutting forces, and is calculated from the radial depth of cut of the work piece W by the rotary tool 1. See also the literature "Y. Altıntas: MANUFACTURING AUTOMATION (2012), 159" for these.

The index calculation unit 22 may calculate the state transition matrix D'represented by the following equation (10) in order to evaluate the stability of the feedback loop 30. In equation (10) below, P and R are 4 × 4 matrices calculated from modal parameters and process gain 31. The modal parameter is a value (M: mass, C: damping, K: spring constant) calculated by curve-fitting the third compliance. Further, in the following equation (10), w _a and w _b are weighting coefficients. For details of the calculation method of the state transition matrix D', refer to Patent No. 6316997, which is the patent document of the present applicant.

In step S25, the index calculation unit 22 calculates the chatter stability using the feedback loop 30 (one-round transfer function D). The chatter stability is an index showing the stability of the feedback loop 30 against chatter vibration. Here, "stability of the feedback loop 30 against chatter vibration" refers to the stability limit depth of cut of the work piece W by the rotary tool 1, the cutting force, and the amplitude due to the chatter vibration of the rotary tool 1 (hereinafter, "vibration amplitude"). It can be evaluated from the three viewpoints of. The stability limit cut amount is a limit cut amount indicating when the cut amount in the tool axis direction of the rotary tool 1 reaches the stability limit.

"High stability of the feedback loop 30 against chatter vibration" refers to a case where the cutting force and the vibration amplitude are attenuated. In such a case, once the chatter vibration occurs, it is attenuated in the feedback loop 30 and then converges. "The chatter vibration is attenuated in the feedback loop 30" means that the chatter vibration (or cutting force) after one loop turns becomes smaller than the chatter vibration (or cutting force) before that. On the other hand, "the stability of the feedback loop 30 against chatter vibration is low" refers to the case where the cutting force and the vibration amplitude are amplified. In such a case, once it occurs, the chatter vibration diverges in the feedback loop 30, and the vibration becomes large. "The chatter vibration diverges in the feedback loop 30" means that the chatter vibration (or cutting force) after one loop turns becomes larger than the chatter vibration (or cutting force) before that.

In the present embodiment, the index calculation unit 22 first calculates an eigenvalue (complex number) of the round-trip transfer function D. Next, the index calculation unit 22 substitutes the reciprocal of the eigenvalue (complex number) of the one-round transfer function D into the following equation (11) to obtain a gain margin gm as chatter stability. In the following equation (11), Λ _R represents the real part of the reciprocal of the eigenvalues of the round transfer function D, and Λ _I represents the imaginary part of the reciprocal of the eigenvalues of the round transfer function D. For these, also refer to the document "E. Shamoto: Analytical prophecy of chatter stability in ball end milling with tool inclination (2009), 353".

The gain margin gm is an index showing the margin of the process gain 31, and indicates how many times the process gain 31 is increased from the current state to reach the stability limit. Specifically, gm <1 is unstable (chatter vibration occurs), gm = 1 is the stability limit, and gm> 1 is stable (chatter vibration does not occur). For example, in the example of FIG. 12, gm> 1 regardless of the rotation speed of the rotary tool 1. Therefore, it can be said that the candidate holder 2 having the gain margin gm exemplified in FIG. 12 is a holder in which chatter vibration does not occur under the conditions of the input parameters.

When the state transition matrix D'is calculated as the feedback loop 30, the index calculation unit 22 may calculate the attenuation degree C _s represented by the following equation (12) as the chatter stability. The degree of damping C _s is an index showing how much the chatter vibration is damped after one rotation of the rotary tool 1. In the following equation (12), λ _max is the maximum value of the eigenvalues of the state transition matrix D'. z is the number of blades of the rotary tool 1. The damping degree _Cs in this case is based on the premise that the rotary tool 1 is an equal pitch tool.

Specifically, when the degree of damping C _s > 1, the larger the value is, the larger the chatter vibration is damped after the rotary tool 1 is rotated. On the other hand, when the degree of attenuation C _s <1, the smaller the value is, the greater the chatter vibration after the rotary tool 1 is rotated. For details of the degree of attenuation Cs, refer to Patent No. _6316997 , which is the patent document of the present applicant. Further, for example, the index calculation unit 22 may calculate the stability limit cut amount as the chatter stability (see FIG. 8). The index calculation unit 22 outputs the calculated gain margin gm to the holder selection unit 23.

The index calculation unit 22 inputs a plurality of values within a predetermined numerical range (lower limit value: minimum rotation speed, upper limit value: maximum rotation speed) instead of one value (rotation speed) as the rotation speed of the cutting parameter. Then, a plurality of chattering stability may be calculated. In this case, the index calculation unit 22 may set the chatter stability having the maximum value or the chatter stability having the minimum value from the plurality of calculated chatter stability as a typical gain margin gm. When the chattering stability with the minimum value is set as a typical gain margin gm, it is possible to evaluate the chattering stability on the safety side in consideration of variations in calculation and vibration measurement. On the other hand, when the chattering stability with the maximum value is set as a typical gain margin gm, the rotation speed at which the chattering stability value is maximized and the gain margin gm are displayed together on the display unit 11. , The user can also know the number of revolutions at which the chatter stability becomes high.

Further, the index calculation unit 22 may input NC data as a cutting parameter to calculate the chatter stability. In this case, the index calculation unit 22 calculates the gain margin gm or the attenuation degree _Cs as the chatter stability for all the paths (tool paths) of the NC data. Then, the index calculation unit 22 may select the one having the smallest value from the calculated gain margin _gm or the attenuation degree Cs and output it to the holder selection unit 23.

In step S26, the index calculation unit 22 determines whether or not the gain margin gm has been calculated for all of the plurality of candidate holders 2. If Yes in step S26, the information processing apparatus 100 shifts to the process of step S27. On the other hand, if No in step S26, the information processing apparatus 100 executes each process of steps S23 to S25 again.

In step S27, the holder selection unit 23 uses the gain margin gm of the plurality of candidate holders 2 acquired from the index calculation unit 22 to make stable holders 2-2 (see FIG. 1) for each of the plurality of candidate holders 2. Decide whether or not. The holder selection unit 23 selects a stable holder 2-2 from a plurality of candidate holders 2, and is provided in the control unit 14 (see FIG. 2). The stable holder 2-2 is a candidate holder 2 in which the degree of resistance to chatter vibration is equal to or higher than the permissible level in the gain margin gm.

In the present embodiment, the holder selection unit 23 compares the gain margin gm with the permissible level value. Then, when the gain margin gm is equal to or greater than the allowable level value, the holder selection unit 23 sets the candidate holder 2 for which the gain margin gm is calculated as the stable holder 2-2. The permissible level value is a value of a gain margin gm in which the degree of difficulty in causing chatter vibration indicates the permissible level. The allowable level value can be set arbitrarily as long as it exceeds 1, but it is preferable to set a value of 2 or more in consideration of modeling error and the like. The holder selection unit 23 executes such a comparison process for all of the plurality of candidate holders 2.

In step S28, the holder selection unit 23 ranks one or more stable holders 2-2 determined in step S27 in descending order of the degree of resistance to chatter vibration. Specifically, the holder selection unit 23 ranks one or more stable holders 2-2 in descending order of the value of the gain margin gm. If only one stable holder 2-2 is selected, the holder selection unit 23 immediately places the selected stable holder 2-2 in the first order.

The ranking of the stable holder 2-2 by the holder selection unit 23 is not limited to the above-described embodiment. The holder selection unit 23 may rank one or more stable holders 2-2 in ascending order of difficulty in causing chatter vibration (in ascending order of gain margin value). That is, the holder selection unit 23 can flexibly rank one or more stable holders 2-2 according to the degree of difficulty in causing chatter vibration. Further, for example, the holder selection unit 23 does not have to rank one or more stable holders 2-2. In this case, the holder selection unit 23 may select the stable holder 2-2 having the largest gain margin gm from one or more stable holders 2-2 as the specific holder 2-1. Alternatively, the holder selection unit 23 may simply display the model numbers and the like of one or more stable holders 2-2 on the display unit 11 together with the gain margin gm.

The calculation result of the index calculation unit 22, the selection result of the holder selection unit 23, and the ranking result may be stored in the server or the storage unit 13 in a state of being incorporated in the holder list, for example. Further, for example, these calculation results may be displayed on the display unit 11. When the process of step S28 is completed, a series of processes by the information processing apparatus 200 is completed.

<Summary>
The information processing apparatus 200 calculates chatter stability (gain margin gm in this embodiment), which is a chatter stability index, in consideration of the cutting conditions of the work piece W. Therefore, by grasping the chattering stability of the plurality of candidate holders 2, it is possible to accurately select the candidate holder 2 from the plurality of candidate holders 2 in which chatter vibration is unlikely to occur. Further, the information processing apparatus 200 includes a holder selection unit 23 that selects a stable holder 2-2 from a plurality of candidate holders 2. Therefore, the candidate holder 2 that is less likely to cause chatter vibration can be easily selected only by grasping the selection result of the holder selection unit 23.

[Third Embodiment]
A third embodiment of the present invention will be described below. The information processing apparatus 300 according to the third embodiment of the present invention is different from the information processing apparatus 100 according to the first embodiment of the present invention in that the control unit 14 includes the holder selection unit 23 shown in FIG. .. The information processing device 300 is also different from the information processing device 100 in that the index calculation unit 22 calculates the gain margin gm as a chatter stability index. Further, the information processing apparatus 300 has a cutting force calculation unit 231, a deflection amount calculation unit 232, and a machining error calculation unit 233, and information processing is performed in that the holder selection unit 23 calculates the machining error of the work piece W. It is different from the device 100 and the information processing device 200 according to the second embodiment of the present invention.

<Functional configuration of information processing equipment>
The functional configuration of the information processing apparatus 300 will be described with reference to FIG. When the holder selection unit 23 of the information processing apparatus 300 has two or more stable holders 2-2 in the plurality of candidate holders 2, the holder selection unit 23 of the two or more touring 4 having the stable holder 2-2 as a component is For each, the machining error of the work piece W is calculated. Hereinafter, the touring 4 having the stable holder 2-2 as a component is referred to as "stable touring". As shown in FIG. 2, the holder selection unit 23 of the information processing apparatus 300 includes a cutting force calculation unit 231, a deflection amount calculation unit 232, a machining error calculation unit 233, and a selection unit 234.

When there are two or more stable holders 2-2 in the plurality of candidate holders 2, the cutting force calculation unit 231 calculates the cutting force acting on the rotary tool 1 for each of the two or more stable touring. The deflection amount calculation unit 232 uses the cutting force and the third compliance of the stable touring for each of the two or more stable tourings, and the amount of the deflection during machining in the rotary tool 1 in the state of being attached to the stable touring (hereinafter referred to as “the amount of deflection”). , Abbreviated as "deflection amount"). The machining error calculation unit 233 calculates the machining error of the work piece W based on the amount of deflection for each of the two or more stable touring. The machining error of the work piece W calculated by the machining error calculation unit 233 is a machining error caused by the action of the cutting force on the rotary tool 1. The selection unit 234 selects a specific holder 2-1 from two or more stable holders 2-2 based on the calculation result of the machining error calculation unit 233.

<Specific processing of information processing equipment>
An example of specific processing of the information processing apparatus 300 will be described with reference to FIGS. 13 and 14. Each process of steps S31 to S37 in the flowchart of FIG. 13 is the same as each process of steps S21 to S27 in the flowchart of FIG. However, the process of step S37 corresponding to the process of step S27 is executed by the cutting force calculation unit 231.

As shown in FIG. 13, when the cutting force calculation unit 231 determines two or more stable holders 2-2 in step S37 (Yes in step S38), the cutting force calculation unit 231 shifts to the process of step S39. In step S39, each of the cutting force calculation unit 231, the deflection amount calculation unit 232, the machining error calculation unit 233, and the selection unit 234 executes a predetermined process to specify from among two or more stable holders 2-2. Holder 2-1 is selected. When the process of step S39 is completed, a series of processes by the information processing apparatus 300 is completed.

On the other hand, when only one stable holder 2-2 is determined in step S27 (No in step S38), the cutting force calculation unit 231 shifts to the process of step S40. In step S40, the cutting force calculation unit 231 sets one determined stable holder 2-2 as the specific holder 2-1. When the process of step S40 is completed, a series of processes by the information processing apparatus 300 is completed.

The details of the process of step S39, in other words, the selection process by the holder selection unit 23 of the information processing apparatus 300 will be described below. As shown in FIG. 14, in step S391, the cutting force calculation unit 231 calculates the cutting force for each of the two or more stable touring. Specifically, the cutting force calculation unit 231 first acquires cutting parameters from the index calculation unit 22. The cutting force calculation unit 231 may acquire cutting parameters from the operation input unit 12 or may acquire cutting parameters from the server or the storage unit 13.

Next, for the stable touring arbitrarily extracted from two or more stable tourings, the cutting force calculation unit 231 first virtually converts the cutting edge 6 of the rotary tool 1 into a plurality of minute cutting edges (not shown). To divide. Next, the cutting force calculation unit 231 calculates the cutting thickness of each of the plurality of minute cutting edges from the cutting parameters. Next, the cutting force calculation unit 231 substitutes each value of the calculated cutting thickness and the cutting force coefficient included in the cutting parameter into the relational expression between the cutting thickness and the cutting force coefficient, thereby cutting the cutting force in three directions. Is calculated. The cutting force in the three directions is composed of a main component force, a back component force, and a component force in a direction orthogonal to these. Then, the cutting force calculation unit 231 converts the coordinates of each of the cutting forces in the three directions into the XYZ directions, calculates the cutting force in the X direction, the Y direction, and the Z direction, and outputs the calculation result to the deflection amount calculation unit 232. ..

In step S392, the deflection amount calculation unit 232 calculates the deflection amount for each of the two or more stable touring. Specifically, the deflection amount calculation unit 232 first acquires the third compliance of stable touring, which is the target of calculation of the cutting force, from the compliance calculation unit 21. Next, the deflection amount calculation unit 232 calculates the deflection amount by solving the equation of motion using the third compliance acquired from the compliance calculation unit 21 and the cutting force acquired from the cutting force calculation unit 231. The deflection amount calculation unit 232 outputs the calculation result to the machining error calculation unit 233.

Here, as a method for solving the equation of motion, a known method such as a frequency domain analysis method or a time domain analysis method can be adopted. When solving the equation of motion using the frequency region analysis method, for example, by adopting a method of repeating the calculation of both until each value of the cutting force and the amount of bending converges, the bending of the rotary tool 1 becomes the cutting force. The amount of deflection considering the effect can be calculated. For details of this method, refer to Patent No. 6176617, which is the patent document of the applicant.

In step S393, the machining error calculation unit 233 calculates the machining error of the work piece W based on the deflection amount acquired from the deflection amount calculation unit 232. Specifically, the machining error calculation unit 233 calculates the cutting edge position of the cutting edge 6 in consideration of the amount of bending. Next, the machining error calculation unit 233 sets the ideal machined surface (not shown) of the work piece W, calculates the distance between the cutting edge position of the cutting edge 6 and the ideal machined surface, and obtains the calculated distance. It is a processing error of the shaving W. For details of this method, refer to Patent No. 6176617, which is the patent document of the applicant. Of course, the method of calculating the processing error of the work piece W is not limited to the above-mentioned method. The processing error calculation unit 233 outputs the calculation result to the selection unit 234.

When the machining error calculation unit 233 calculates the machining error of the work piece W for all of the two or more stable touring (Yes in step S394), the process proceeds to the process of step S395. On the other hand, when some of the two or more stable tourings have not completed the calculation of the machining error of the work piece W (No in step S394), the information processing apparatus 300 again performs steps S391 to S393. Execute each process.

In step S395, the selection unit 234 identifies the stable touring having the smallest processing error value by mutually comparing the magnitude of the processing error of the work piece W acquired from the processing error calculation unit 233. do. Then, the selection unit 234 selects the stable holder 2-2 constituting the specified stable touring as the specific holder 2-1.

The holder selection unit 23 of the information processing apparatus 300 does not have to select the specific holder 2-1 from the two or more stable holders 2-2. In other words, the holder selection unit 23 of the information processing apparatus 300 does not have to include the selection unit 234. In this case, the holder selection unit 23 of the information processing apparatus 300 may display, for example, the calculation result of the processing error calculation unit 233 on the display unit 11 together with the gain margin gm. Alternatively, the machining error calculation unit 233 may rank two or more stable holders 2-2 in ascending order of machining error, or may rank them in descending order of machining error.

The calculation results of the cutting force calculation unit 231 and the deflection amount calculation unit 232 and the machining error calculation unit 233 may be stored in the server or the storage unit 13 in a state of being incorporated in the holder list, for example. Further, for example, these calculation results and the selection result of the selection unit 234 may be displayed on the display unit 11. When the process of step S395 is completed, the selection process (process of step S39) by the holder selection unit 23 of the information processing apparatus 300 is completed.

<Summary>
The information processing apparatus 300 calculates the machining error of the work piece W for each of the two or more stable touring. Therefore, even if there are two or more stable holders 2-2 in the plurality of candidate holders 2, by grasping the machining error of the work piece W, the degree of resistance to chatter vibration is above the permissible level. You can select the stable holder 2-2, which has high processing accuracy. Further, the information processing apparatus 300 includes a selection unit 234. Therefore, by grasping the selection result of the selection unit 234, the degree of resistance to chatter vibration is equal to or higher than the permissible level among the two or more stable holders 2-2, and the stable holder having the highest processing accuracy. 2-2 can be selected as the specific holder 2-1.

[Example of implementation by software]
The functions of the information processing devices 100 to 300 (hereinafter referred to as "devices") are programs for operating a computer as the device, and as each control block of the device (particularly, each part included in the control unit 14). It can be realized by a program for operating a computer.

In this case, the above-mentioned device includes a computer having at least one control device (for example, a processor) and at least one storage device (for example, a memory) as hardware for executing the above-mentioned program. By executing the above-mentioned program by the control device and the storage device, each function described in the first to third embodiments is realized.

The above-mentioned program may be recorded on one or more computer-readable recording media rather than temporarily. This recording medium may or may not be provided by the above-mentioned device. In the latter case, the aforementioned program may be supplied to the aforementioned device via any wired or wireless transmission medium.

Further, some or all of the functions of the above-mentioned control blocks can be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each of the above-mentioned control blocks is formed is also included in the category of the present invention. In addition to this, it is also possible to realize the functions of the above-mentioned control blocks by, for example, a quantum computer.

[Additional notes]
The present invention is not limited to the first to third embodiments described above, and various modifications can be made within the scope of the claims, and the technical means disclosed in the different embodiments may be appropriately combined. The obtained embodiments are also included in the technical scope of the present invention.

〔Example〕
Hereinafter, examples of the present invention (first to third embodiments) will be described with reference to FIGS. 15 to 19. In the second embodiment, a four-flute carbide square end mill (hereinafter abbreviated as "square end mill") having a diameter of 8 mm and a protrusion length of 48 mm was used as the rotary tool 1. In the first and third embodiments, as the rotary tool 1, a carbide ball end mill having a diameter of 8 mm and a protrusion length of 48 mm and two blades (hereinafter, abbreviated as “ball end mill”) was used. Further, in this embodiment, as a plurality of candidate holders 2, four types of holders having the same diameter but different lengths in the tool axis direction (Mega New Baby Chuck Series 13N-60, 13N-90, 13N-120, 13N- 165: Daishowa Seiki Co., Ltd.) was used. Hereinafter, the holder (13N-60) is referred to as the "first holder", the holder (13N-90) is referred to as the "second holder", the holder (13N-120) is referred to as the "third holder", and the holder (13N-165) is referred to as the "first holder". It is called "4 holder".

In this embodiment, MU-400VA (Okuma 5-axis machining center) was used as the machine tool 3. Then, each of the first to fourth holders holding the square end mill or the ball end mill was attached to the machine tool 3 to form the first to fourth touring. In this embodiment, a work having a substantially cubic shape (hereinafter, abbreviated as “SKD61”) using a die steel SKD61 having a Rockwell hardness of 45 as a forming material was used as the work piece W.

In this embodiment, a stationary personal computer (hereinafter referred to as “PC”) having the same configuration as that of the information processing apparatus 300 is used. Then, the NC optimization systems "HiSimDynaOpt_Chat" and "HiSimDynaBase_Chat" developed by the inventors were installed on the PC to simulate the cutting process of SKD61 by each of the first to fourth touring. Further, in this embodiment, in the above-mentioned simulation, the gain margin gm of each of the first to fourth touring was analyzed. That is, the NC simulator was made to play the roles of the compliance calculation unit 21 and the index calculation unit 22 of the PC.

<First Example>
First, the first embodiment of the present invention will be described with reference to FIGS. 15 to 17. In the first embodiment, holder selection using the maximum value of the compliance gain as the chatter stability index will be described. Specifically, by attaching only the first to fourth holders to the machine tool 3 and performing vibration measurement by the method described in [First Embodiment], the compliance matrix R _2b2b of the above-mentioned equation (1) (1) Second compliance) was calculated. Of the compliance matrices R _2b2b of each of the first to fourth holders, the compliance h _2b2b is shown in FIG.

Next, the compliance matrix _Ra (first compliance) of the above-mentioned equation (4) was calculated by the method described in [First Embodiment]. Of the compliance matrix _Ra , the 1-by-1 component (deflection / force) is shown in FIG. Next, the compliance matrix G ₁₁ was calculated using the compliance matrix R _a , the compliance matrix R _2b2b , and the above equation (6). The compliance H ₁₁ (third compliance) in the compliance matrix G ₁₁ is shown in FIG. Specifically, the graph of the broken line shown by "estimation" in FIG. 17 is the compliance H11 calculated by using the equation ( ₆ ). In addition, FIG. 17 is a graph of compliance H ₁₁ when the ball end mill is vibrated and measured with each of the first to fourth holders holding the ball end mill attached to the machine tool 3 (“Measurement” in the figure. ") Is also shown in the figure. "A state in which each of the first to fourth holders holding the ball end mill is attached to the machine tool 3" is, in other words, a state in which the first to fourth touring are configured.

As shown in FIG. ₁₇ , the “estimated” graph of compliance H11 generally matched the “measurement” graph. From this, it was confirmed that the actual compliance of the touring can be estimated by the calculation of the compliance _H11 by the method described in [1st embodiment], that is, the calculation of the 3rd compliance. The calculated maximum value of the compliance gain of the first to fourth touring is shown in Table 2 below. As shown in Table 2 below, it was the maximum (15.51 μm / N) in the first touring and the minimum (3.249 μm / N) in the third touring. Based on this result, it can be said that it is most preferable to select the third holder.

In the conventional holder selection method, since the static rigidity of the first to fourth holders is simply compared, the first holder having a larger diameter and a shorter length in the tool axis direction is selected as the specific holder 2-1. Will be done. On the other hand, according to the method described in [First Embodiment], the third holder is selected as the specific holder 2-1. Here, it is estimated that the unconditional stability limit depth of cut of the third holder is about four times or more that of the first holder from the results in Table 2 described above. From these facts, according to the method described in [1st Embodiment], it is possible to process with a processing efficiency of about 4 times or more (that is, a processing time of about 1/4) as compared with the conventional holder selection method. Was estimated. Further, in the first embodiment, it was found that a holder that is less likely to cause chatter vibration can be selected without using cutting parameters.

The results when a ball end mill having a different protrusion length from the ball end mill of the first embodiment is used are shown in Table 3 below. As shown in Table 3 below, for example, when the ball end mill is D8L56 (diameter 8 mm, protrusion length 56 mm), the maximum value of the compliance gain of the fourth holder is the minimum (6.73 μm / N). Then, the fourth holder was selected as the holder in which chatter vibration is unlikely to occur. As described above, according to the method described in [First Embodiment], it has been found that a holder that is less likely to cause chatter vibration can be selected according to the shape of the rotary tool 1.

For 8 types of touring consisting of a combination of 2 types of ball end mills and 4 types of holders shown in Table 3 above, when the compliance of each is obtained by vibration measurement, it is measured including the setup of vibration measurement. It takes about an hour to finish. The vibration measurement in this case is premised on attaching the first to fourth holders holding the D8L56 or D8L64 to the machine tool 3. Further, the machine tool 3 cannot be used for the production of the product during the vibration measurement.

In that respect, according to the method described in [First Embodiment], the compliance of the candidate holder 2 (the first to fourth holders in the first embodiment) can be measured in advance. Therefore, it is only necessary to calculate the difference in the tool shape such as the protrusion length and the difference in the material, and the time for selecting the holder can be significantly shortened. In the first embodiment, it was possible to select a holder (the fourth holder in the case of D8L56 and the third holder in the case of D8L64) in which chatter vibration is unlikely to occur in about several seconds.

<Second Example>
Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, as shown in FIG. 18, the side surface machining of the SKD 61 was simulated under the same cutting conditions for each of the first to fourth touring. Then, in this simulation, the gain margin gm of each of the first to fourth touring was analyzed. In the second embodiment, the conditions shown in Table 4 below are set as cutting parameters (cutting conditions).

The analysis results of the PC are shown in Table 5 below. As shown in Table 5 below, when the cutting amount in the tool axis direction (“Z cutting amount” in FIG. 18: the same applies hereinafter) is 0.5 mm, the gain margin gm in all of the first to fourth touring. Was greater than 1, and it was predicted that chatter vibration would not occur. Further, when the depth of cut in the tool axis direction was 1.0 mm, the gain margin gm was smaller than 1 (0.592) only in the fourth touring, and it was predicted that chatter vibration would occur. Further, when the depth of cut in the tool axis direction was 1.5 mm, the gain margin gm was larger than 1 (3.004) only in the third touring, and it was predicted that chatter vibration would not occur.

Since the value of the gain margin gm is a value indicating how many times the process gain can be increased, in other words, how many times the depth of cut in the tool axis direction can be increased, the third holder cuts in the tool axis direction. It can be seen that the filling amount can be increased to about 4.5 mm. That is, the gain margin gm is about 1 when the depth of cut in the tool axis direction is 4.5 mm. In the second embodiment, the gain margin gm is calculated from the three types of tool axial depth of cut, but to what extent is the gain margin gm calculated from one type of tool axial depth of cut? It is possible to know whether the cutting amount can be increased (stability limit cutting amount). Further, when the third holder is compared with the first holder selected by the conventional holder selection method, the third holder has a depth of cut about 4.5 times larger in the tool axis direction than the first holder. It was confirmed that it is possible to improve the processing efficiency by about 4.5 times.

As described above, by setting the cutting parameters (cutting conditions) from the results of the second embodiment, it is possible not only to know a suitable holder in terms of avoiding chatter vibration, but also to know the cutting conditions in which chatter vibration does not occur. It turned out that it is possible to know (the amount of cut in the tool axis direction). From this, it can be said that the chattering stability such as the gain margin gm is a particularly effective index in the roughing process that contributes to the improvement of the machining efficiency.

<Third Example>
Next, a third embodiment of the present invention will be described with reference to FIG. Also in the third embodiment, as shown in FIG. 19, for each of the first to fourth touring, the gain margin gm in the contour line machining of the side portion (specifically, the inclined surface of the side portion) of the SKD 61 is cut in the same manner. Simulated under the conditions. In the third embodiment, the inclination angle of the inclined surface was set to 85 °. The inclination angle of the inclined surface is an inclination angle when the bottom surface of the work piece W is set as a reference surface (0 °). Further, in the third embodiment, the conditions shown in Table 6 below are set as the cutting conditions.

Under the cutting conditions shown in Table 6 above, the gain margin gm is sufficiently larger than 1 in all of the 1st to 4th touring (see Table 7 below), and chatter vibration occurs in all of the 1st to 4th holders. It was predicted that it would be a stable holder that would not occur. Therefore, the NC simulator was made to calculate the machining error of each of the first to fourth touring, and the specific holder 2-1 was selected from the first to fourth holders. That is, the NC simulator was made to play the role of the processing error calculation unit 233 and the selection unit 234 of the PC. The calculation results of the processing error are shown in Table 7 below.

As shown in Table 7 above, it was predicted that the machining error would be smaller in the order of "first holder, fourth holder, second holder, third holder". Then, from this result, the first holder was selected as the specific holder 2-1.

In the finishing process, it is required that the processing error is small in addition to the absence of chatter vibration. Here, each value of the cut amount in the normal direction of the machined surface and the pick feed (cut amount in the inclined surface direction) in the finishing process is often set according to the required surface roughness and the like, and the second It is not necessary to take a large value as in the embodiment. In that respect, in the third embodiment, by selecting a holder having a small machining error from the first to fourth holders having a sufficiently large gain margin gm (for example, 2 or more), chatter vibration does not occur and machining error is also small. It turned out to be possible.

From the results of the third embodiment, by considering not only the chattering stability such as the gain margin gm but also the machining error, chatter vibration is less likely to occur and the machining accuracy is the highest depending on the shape and cutting conditions of the rotary tool 1. It was presumed that the higher holder could be selected as the specific holder 2-1.

1 Rotating tool (tool)
2 Candidate holder (holder)
2-2 Stable holder 3 Machine tool 4 Tooling 21 Compliance calculation unit 22 Index calculation unit 23 Holder selection unit 30 Feedback loop 31 Process gain 100, 200, 300 Information processing device W Work piece

Claims (8)

By acquiring the first compliance information indicating the compliance of the tool for machining the work piece and the second compliance information indicating the compliance of the holder for holding the tool for each of the plurality of holders. , A compliance calculation unit that calculates the compliance of a touring having the holder holding the tool for each of the plurality of holders.
For each of the plurality of holders, the degree of resistance to chatter vibration generated during machining of the work piece by the tool is shown by using the compliance of the touring having the holder calculated by the compliance calculation unit. An information processing device equipped with an index calculation unit that calculates a chatter stability index. The touring has a machine tool and
The information processing apparatus according to claim 1, wherein the holder holding the tool constituting the touring is attached to the machine tool. The information processing apparatus according to claim 1 or 2, wherein the index calculation unit calculates the maximum value of the compliance gain, which is the magnitude of the compliance, as the chatter stability index. The index calculation unit
For the machining process of the work piece, a feedback loop composed of the process gain calculated by using the machining parameters constituting the machining conditions of the work piece and the compliance of the touring is generated.
The information processing apparatus according to claim 1 or 2, wherein the chatter stability indicating the stability of the feedback loop against the chatter vibration is calculated as the chatter stability index. Claims 1 to 4 further include a holder selection unit for selecting a stable holder whose degree of difficulty in chatter vibration is equal to or higher than an allowable level in the chatter stability index from the plurality of holders. The information processing apparatus according to any one of the following items. When there are two or more stable holders in the plurality of holders, the holder selection unit has the stable holder that acquires the machining parameters constituting the machining conditions of the work piece and holds the tool. For each of the two or more tourings
(I) Calculate the cutting force acting on the tool,
(Ii) Using the cutting force and the compliance of the touring calculated by the compliance calculation unit, the amount of deflection of the tool is calculated.
(Iii) The information processing apparatus according to claim 5, which calculates a machining error of the work piece due to the action of the cutting force on the tool based on the amount of the deflection. The control program for operating a computer as the information processing apparatus according to claim 1, wherein the computer functions as the compliance calculation unit and the index calculation unit. By acquiring the first compliance information indicating the compliance of the tool for machining the work piece and the second compliance information indicating the compliance of the holder for holding the tool for each of the plurality of holders. , A compliance calculation step for calculating the compliance of a touring having the holder holding the tool for each of the plurality of holders.
For each of the plurality of holders, the degree of resistance to chatter vibration generated during machining of the work piece by the tool is determined by using the compliance of the touring having the holder calculated in the compliance calculation step. An information processing method, including an index calculation step for calculating the chatter stability index to be shown.

Images