Machining condition determination assistance device for machine tool

Abstract

To provide a machining condition determination assistance device for a machine tool, which can shorten working time for calculating collet dynamic characteristics, improve workability, and easily and highly accurately perform stability limit analysis of the machine tool.SOLUTION: A machining condition determination assistance device 100 for a machine tool 1 comprises: a tool dynamic characteristic acquisition unit 101; a holder dynamic characteristic acquisition unit 103; and a tool spindle dynamic characteristic acquisition unit 105. The device further comprises a collet dynamic characteristic database 107 that stores at least a correlation among the shank diameter of a tool, the holder diameter of a holder, and collet dynamic characteristics, a collet dynamic characteristic calculation unit 108 that interpolates and calculates collet dynamic characteristics to be analyzed from the shank diameter, the holder diameter, and the correlation stored in the database 107 in the tool to be analyzed, and an analysis unit 120 that performs stability limit analysis of the machine tool 1 on the basis of the tool dynamic characteristics of the tool to be analyzed, the holder dynamic characteristics, the tool spindle dynamic characteristics, and the collet dynamic characteristics.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a machining condition determination support device for a machine tool. [Background technology]

[0002] In machine tools that machine workpieces with tools, suppressing chatter is important for improving the machining accuracy of the workpiece. Therefore, it is known to grasp the frequency response characteristics of the machine tool through hammering tests on the tools and then perform stability limit analysis of the machine tool. By determining machining conditions that fall within the stable region based on the results of the stability limit analysis, it is possible to suppress chatter.

[0003] Hammering tests and the like are performed with the tool spindle of the machine tool stationary, which is different from actual machining conditions. Patent Document 1 describes a configuration in which dynamic characteristics corresponding to a specified tool and tool holder are extracted from a dynamic characteristics database in which dynamic characteristics of a plurality of tools and tool holders are stored in advance using an appearance image of the analysis target captured by a photographing device, and stability limit analysis of the machine tool is performed based on the extracted dynamic characteristics. Patent Document 2 also describes a configuration in which stability limit analysis is performed using a pre-created analytical model of the tool and tool holder. Patent Document 3 describes a configuration in which a stability limit diagram is created taking into account the tool specifications and the material of the workpiece, and machining conditions under which forced chatter vibration does not occur are output. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-95069 [Patent Document 2] Japanese Patent Publication No. 2022-115435 [Patent Document 3] Japanese Patent Application Publication No. 2023-179109 Summary of the Invention [Problem to be solved by the invention]

[0005] However, a tool is gripped by a collet provided in a holder, and the collet dynamic characteristics of the collet change depending on the combination of the tool and the holder and the collet tightening torque. Therefore, in the configuration disclosed in Patent Document 1, in order to extract collet dynamic characteristics corresponding to a specified tool and holder with high accuracy using an external image captured by a photographing device, the amount of data in the dynamic characteristics database tends to increase, reducing workability and lengthening the extraction work time. Furthermore, the configurations disclosed in Patent Documents 2 and 3 do not take any specific measures to shorten the work time while extracting collet dynamic characteristics with high accuracy. Therefore, there is room for improvement in order to easily and accurately perform stability limit analysis of machine tools.

[0006] The present invention aims to provide a machine tool machining condition determination support device that can reduce the work time and improve workability required to calculate collet dynamic characteristics, and can easily and accurately analyze the stability limits of machine tools. [Means for solving the problem]

[0007] One aspect of the present invention is A machining condition determination support device for a machine tool in which a tool is attached to a tool spindle provided on a machine body of the machine tool via a holder having a collet that grips the tool, a tool dynamic characteristic acquisition unit that acquires a tool dynamic characteristic, which is a dynamic characteristic of vibration in the tool to be analyzed; a holder dynamic characteristic acquisition unit that acquires a holder dynamic characteristic, which is a dynamic characteristic of vibration in the holder to be analyzed; a tool spindle dynamic characteristic acquisition unit that acquires a tool spindle dynamic characteristic, which is a dynamic characteristic of vibration in the tool spindle to be analyzed; a collet dynamic characteristics database that stores a correspondence relationship between at least a shank diameter of the tool for database creation, a holder diameter of the holder for database creation, and a collet dynamic characteristics that are dynamic characteristics of vibration in the collet for database creation; a collet dynamic characteristic calculation unit that calculates the collet dynamic characteristic of the analysis target by interpolation from the shank diameter of the tool that is the analysis target, the holder diameter of the holder that is the analysis target, and the correspondence relationship stored in the collet dynamic characteristic database; an analysis unit that performs a stability limit analysis of the machine tool based on the tool dynamic characteristics of an analysis target, the holder dynamic characteristics of an analysis target, the tool spindle dynamic characteristics of an analysis target, and the collet dynamic characteristics of an analysis target; The present invention relates to a machining condition determination support device for a machine tool equipped with the above-mentioned. [Effects of the Invention]

[0008] The inventors of the present application discovered that, among the specifications of the tool and holder, at least the tool shank diameter and holder diameter have a high correlation with the collet dynamic characteristics. Based on this, in the above-described aspect, the correspondence relationship stored in the collet dynamic characteristics database is a correspondence relationship between the tool shank diameter, holder diameter, and collet dynamic characteristics that exhibits a high correlation with the collet dynamic characteristics, so that the collet dynamic characteristics can be obtained with high accuracy by using the tool shank diameter and holder diameter. Furthermore, even if the combination of the tool and holder is changed, there is no need to obtain actual measured values ​​by hammering measurement each time, thereby reducing work time.

[0009] Furthermore, because the collet dynamic characteristics to be analyzed are calculated by interpolating the correspondence relationships stored in the collet dynamic characteristics database, they can be calculated with high accuracy without excessively increasing the data density of the correspondence relationships stored in the collet dynamic characteristics database. As a result, the effort required to create the collet dynamic characteristics database can be reduced, and the amount of data required for the collet dynamic characteristics database can be small, making it easier to handle the collet dynamic characteristics database and improving workability. Furthermore, by using the collet dynamic characteristics obtained in this manner, stability limit analysis of machine tools can be performed easily and with high accuracy.

[0010] As described above, according to the above aspect, it is possible to provide a machine tool machining condition determination support device that can reduce the work time required to calculate collet dynamic characteristics and improve workability, and can easily and accurately analyze the stability limits of machine tools. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of a machine tool according to a first embodiment. [Figure 2] 1A is an external side view of a tool according to a first embodiment, and FIG. 1B is an axial cross-sectional view of the tool. [Figure 3] FIG. 2 is a functional block diagram of the machining condition determination support device according to the first embodiment. [Figure 4] FIG. 4 is a conceptual diagram showing correspondence relationships stored in a collet dynamic characteristics database in the first embodiment. [Figure 5] (a) A diagram showing test results regarding collet dynamic characteristics and shank diameter in embodiment 1, (b) A diagram showing test results regarding collet dynamic characteristics and holder diameter, and (c) A diagram showing test results regarding collet dynamic characteristics and tool protrusion length / shank diameter. [Figure 6] (a) A first conceptual diagram illustrating the process of interpolating collet dynamic characteristics, (b) a second conceptual diagram illustrating the process of interpolating collet dynamic characteristics, and (c) a third conceptual diagram illustrating the process of interpolating collet dynamic characteristics in embodiment 1. [Figure 7] FIG. 4 is a conceptual diagram showing frequency characteristics of compliance of the entire device in the first embodiment. [Figure 8] FIG. 3 is a conceptual diagram of a stability limit diagram showing the relationship between the rotation speed of the spindle device and the depth of cut limit in the first embodiment. [Figure 9] 4 is a flowchart showing a processing condition quality determination process in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1. Overview of the machining condition determination support device 100 The machining condition determination support device 100 of the first embodiment is a device for supporting the determination of machining conditions for the machine tool 1 shown in Fig. 1. The machine tool 1, the tool unit, and the machining condition determination support device 100 will be described in detail below.

[0013] 2. Configuration of machine tool 1 The machine tool 1 is a device that processes the workpiece W by moving the tool unit T (mounting member) relative to the workpiece W. Here, the tool unit T is a unit that includes a tool and a holder that holds the tool, as will be described later. The target machine tool 1 is made up of multiple structures for moving the tool unit T relative to the workpiece W. The target machine tool 1 is a machine tool that performs cutting or grinding, such as a machining center, lathe, milling machine, gear processing device, grinding machine, etc.

[0014] An example of a machine tool 1 will be described with reference to FIG. 1. In this example, the machine tool 1 is exemplified as a machining center capable of tool exchange. A machining center serving as the machine tool 1 can perform basic metal cutting processes such as end milling, milling, boring, and drilling, as well as gear skiving and hobbing to machine a tooth profile into a workpiece W. Furthermore, the machining center serving as the machine tool 1 is basically configured as a horizontal machining center. Note that although the above configuration is exemplified for the machine tool 1, other configurations such as a vertical machining center can also be applied.

[0015] As shown in FIG. 1, the machine tool 1 has, for example, three mutually orthogonal linear axes (X-axis, Y-axis, and Z-axis) as drive axes. Here, the direction of the rotation axis of the tool unit T (equal to the rotation axis of the tool spindle) is defined as the Z-axis direction, and two axes perpendicular to the Z-axis direction are defined as the X-axis and Y-axis directions. In FIG. 1, the horizontal direction is defined as the X-axis direction, and the vertical direction is defined as the Y-axis direction. Furthermore, the machine tool 1 further has, as drive axes, two rotation axes (B-axis and Cw-axis) for changing the relative attitude of the tool unit T and the workpiece W. The machine tool 1 also has a Ct-axis as a rotation axis for rotating the tool unit T.

[0016] In other words, machine tool 1 is a five-axis machine (a six-axis machine when the tool spindle (Ct axis) is taken into account) capable of machining free-form surfaces. Here, machine tool 1 may be configured to have an A-axis (a rotation axis about the X-axis in the reference state) and a B-axis, or an A-axis and a Cw-axis, instead of a configuration having a B-axis (a rotation axis about the Y-axis in the reference state) and a Cw-axis. Also, machine tools having a different number of drive axes from that of a five-axis machine can be applied.

[0017] The tool unit T is a rotary tool used to machine the workpiece W. The tool unit T is detachably attached to the tool spindle 33b of the tool spindle device 33. The tool unit T is equipped with a tool 52, such as an end mill, a milling cutter, a boring cutter, a drill, a gear skiving cutter, or a hob cutter. The tool unit T includes a holder 51 attached to the spindle device and a tool 52 held by the holder 51.

[0018] In the machine tool 1, the configuration for relatively moving the tool unit T and the workpiece W can be selected as appropriate. In this example, the machine tool 1 allows the tool unit T to move linearly in the Y-axis and Z-axis directions, the workpiece W to move linearly in the X-axis direction, and the workpiece W to rotate about the B-axis and Cw-axis. In addition, the tool unit T can rotate about the Ct-axis.

[0019] The machine tool 1 includes a bed 10, a workpiece holding device 20, and a tool holding device 30. The bed 10 is formed in any shape, such as a substantially rectangular shape, and is installed on an installation surface. The workpiece holding device 20 allows the workpiece W to move linearly in the X-axis direction relative to the bed 10 and to rotate about the B-axis and Cw-axis. The workpiece holding device 20 mainly includes an X-axis moving table 21, a B-axis rotating table 22, and a workpiece spindle device 23.

[0020] The X-axis moving table 21 is provided so as to be movable in the X-axis direction relative to the bed 10. Specifically, a pair of X-axis guide rails extending in the X-axis direction (front-to-back direction in FIG. 1) are provided on the bed 10, and the X-axis moving table 21 is driven by a linear motor or a ball screw mechanism (not shown), so that it moves back and forth in the X-axis direction while being guided by the pair of X-axis guide rails.

[0021] The B-axis rotating table 22 is installed on the upper surface of the X-axis moving table 21, and moves back and forth in the X-axis direction integrally with the X-axis moving table 21. The B-axis rotating table 22 is also provided so as to be rotatable about the B-axis relative to the X-axis moving table 21. A rotary motor (not shown) is housed in the B-axis rotating table 22, and the B-axis rotating table 22 is rotatable about the B-axis when driven by the rotary motor.

[0022] The workpiece spindle device 23 is mounted on the B-axis rotary table 22 and rotates about the B-axis integrally with the B-axis rotary table 22. The workpiece spindle device 23 comprises a workpiece spindle base 23a, a workpiece spindle housing 23b, and a workpiece spindle 23c. The workpiece spindle base 23a is fixed to the upper surface of the B-axis rotary table 22.

[0023] The workpiece spindle housing 23b is fixed to the workpiece spindle base 23a and has a cylindrical inner peripheral surface centered on the Cw-axis centerline, which is perpendicular to the B-axis centerline. The workpiece spindle 23c is rotatably supported by the workpiece spindle housing 23b. The workpiece W is detachably held by the workpiece spindle 23c. In other words, the workpiece W is held by the workpiece spindle housing 23b rotatably about the Cw-axis, and rotates integrally with the workpiece W.

[0024] A rotary motor (not shown) for rotating the work spindle 23c and a detector (not shown) such as an encoder for detecting the rotation angle of the work spindle 23c are provided inside the work spindle housing 23b. In this manner, the work holding device 20 enables the workpiece W to move in the X-axis direction relative to the bed 10 and to rotate about the B-axis and the Cw-axis.

[0025] The tool holding device 30 mainly includes a column 31, a saddle 32, and a tool spindle device 33. The column 31 is provided so as to be movable in the Z-axis direction relative to the bed 10. Specifically, the bed 10 is provided with a pair of Z-axis guide rails extending in the Z-axis direction (left and right direction in FIG. 1), and the column 31 is driven by a linear motor or a ball screw mechanism (not shown), so that it moves back and forth in the Z-axis direction while being guided by the pair of Z-axis guide rails.

[0026] The saddle 32 is disposed on the side of the column 31 facing the workpiece W (the left side in FIG. 1), parallel to a plane perpendicular to the Z-axis direction. A pair of Y-axis guide rails extending in the Y-axis direction (the up-down direction in FIG. 1) are provided on the side of the column 31, and the saddle 32 is driven by a linear motor or a ball screw mechanism (not shown) to reciprocate in the Y-axis direction.

[0027] The tool spindle unit 33 is mounted on the saddle 32 and moves integrally with the saddle 32 in the Y-axis direction. The tool spindle unit 33 includes a tool spindle housing 33a and a tool spindle 33b. The tool spindle housing 33a is fixed to the saddle 32 and has a cylindrical inner circumferential surface centered on a Ct-axis center line parallel to the Z-axis. The tool spindle 33b is rotatably supported by the tool spindle housing 33a. A tool unit T is detachably held by the tool spindle 33b. In other words, the tool spindle 33b holds the tool unit T in the tool spindle housing 33a rotatably about the Ct-axis, and rotates integrally with the tool unit T.

[0028] A tool rotation motor (not shown) that rotates the tool spindle 33b and a detector (not shown) such as an encoder that detects the rotation angle of the tool spindle 33b are provided inside the tool spindle housing 33a. In this way, the tool holding device 30 holds the tool unit T so that it can move in the Y-axis direction and the Z-axis direction relative to the bed 10 and can rotate about the Ct axis.

[0029] 3. Tool unit T configuration Examples of the tool unit T will be described with reference to FIGS. 2(a) and 2(b). A first example of the tool unit T is an end mill having a large-diameter tool 52. As shown in FIG. 2(a), the tool unit T includes a holder 51 and a tool 52. The holder 51 may be a BT shank, a BBT shank, an HSK shank, a CAPTO shank, or the like. The holder 51 in this example is a BT shank or a BBT shank.

[0030] As shown in Fig. 2(b), the holder 51 includes a holder body 51a and a collet 51b as an elastic support member. As shown in Figs. 2(a) and 2(b), the holder body 51a includes a tapered portion 51a1 attached to the tool spindle 33b, an ATC locking portion 51a2 held by an arm of a tool changer (not shown), and a tool holding portion 51a3 that holds a tool 52. Here, in the holder bodies 51a of the multiple tool units T held by the machine tool 1, the tapered portions 51a1 are formed in the same shape.

[0031] In this embodiment, the shape of the holder body 51a is not limited, and for example, the holder diameter D1, which is the outer diameter of the tool holding portion 51a3, and the holder length L1, which is the axial length of the tool holding portion 51a3, can be set to any desired values. Furthermore, in the holder body 51a, the outer shape of the tool holding portion 51a3 can be, for example, cylindrical, tapered, or with a tapered angle.

[0032] Collet 51b is located inside tool holding portion 51a3 of holder body 51a and is interposed between the inner peripheral surface of tool holding portion 51a3 and the outer peripheral surface of tool 52. Collet 51b is configured to be elastically deformable and elastically supports tool 52 relative to tool holding portion 51a3. Collet 51b has a shape that corresponds to holder diameter D1 of holder body 51a and shank diameter D2 of tool 52. Furthermore, collet 51b has a shape that corresponds to the outer shape of tool holding portion 51a3. In other words, the collet type of collet 51b can be determined, for example, by the outer shape of tool holding portion 51a3.

[0033] The tool 52 constituting the tool unit T is an end mill, a milling cutter, a boring cutter, a drill, a gear skiving cutter, a hob cutter, or the like. The tool 52 includes a tool shank portion 52a held by the collet 51b, and a tool protrusion portion 52b that protrudes outward from the collet 51b when the tool 52 is held by the collet 51b. The tool protrusion portion 52b comes into contact with the workpiece W to machine the workpiece W. The length L2 of the tool protrusion portion 52b in the protruding direction can be set as appropriate.

[0034] 4. Configuration of the machining condition determination support device 100 The configuration of a machining condition determination support device 100 of this embodiment will be described with reference to Fig. 3 to Fig. 9. As shown in Fig. 3, the machining condition determination support device 100 (hereinafter referred to as the "support device") includes a tool dynamic characteristic acquisition unit 101, a tool model storage unit 102, a holder dynamic characteristic acquisition unit 103, a holder model storage unit 104, a tool spindle dynamic characteristic acquisition unit 105, a tool spindle model storage unit 106, a collet dynamic characteristic database 107, a collet dynamic characteristic calculation unit 108, a collet type acquisition unit 109, a shank diameter acquisition unit 110, a holder diameter acquisition unit 111, an L2 / D2 acquisition unit 112, an analysis unit 120, and a machining condition acceptability determination unit 130. The support device 100 includes a calculation unit capable of executing predetermined programs and a storage unit capable of storing various information.

[0035] 4-1. Tool dynamic characteristics acquisition section 101 3 acquires tool dynamic characteristics, which are dynamic characteristics of vibrations in the tool 52 to be analyzed. The method of acquiring the tool dynamic characteristics is not limited, and the tool dynamic characteristics may be acquired by performing a hammering test on the tool 52 alone, or a tool model in which the tool 52 is modeled in advance may be created and the dynamic characteristics of the tool 52 may be acquired from the tool model. In this embodiment, a tool model in which the tool 52 is modeled in advance is created and stored in the tool model storage unit 102. Then, the tool dynamic characteristics acquisition unit 101 calls the tool model stored in the tool model storage unit 102 to acquire the tool dynamic characteristics of the tool to be analyzed.

[0036] 4-2. Holder dynamic characteristics acquisition unit 103 The holder dynamic characteristic acquisition unit 103 shown in Fig. 3 acquires holder dynamic characteristics, which are the dynamic characteristics of vibration in the holder 51 to be analyzed. The method for acquiring the holder dynamic characteristics is not limited, and the holder dynamic characteristics may be acquired by performing a hammering test on the holder 51 alone, or a holder model that models the holder 51 in advance may be created and the dynamic characteristics of the holder 51 may be acquired from the holder model. In this embodiment, a holder model that models the holder 51 in advance is created and stored in the holder model storage unit 104. Then, the holder dynamic characteristic acquisition unit 103 calls the holder model stored in the holder model storage unit 104 to acquire the holder dynamic characteristics of the analysis target.

[0037] 4-3. Tool spindle dynamic characteristics acquisition section 105 The tool spindle dynamic characteristic acquisition unit 105 shown in Fig. 3 acquires the tool spindle dynamic characteristic, which is the dynamic characteristic of vibration in the tool spindle 33b. The method of acquiring the tool spindle dynamic characteristic is not limited, and the tool spindle dynamic characteristic may be acquired by performing a hammering test on the tool spindle 33b alone, or a tool spindle model in which the tool spindle 33b is modeled in advance may be created, and the dynamic characteristic of the tool spindle 33b may be acquired from the tool spindle model. In this embodiment, a tool spindle model in which the tool spindle 33b is modeled in advance is created and stored in the tool spindle model storage unit 106. The tool spindle dynamic characteristic acquisition unit 105 then calls the tool model stored in the tool spindle model storage unit 106 to acquire the tool spindle dynamic characteristic of the analysis target.

[0038] 4-4. Collet Dynamic Characteristics Database 107 3 stores correspondence relationships between at least the shank diameter D2 of the database creation tool 52, the holder diameter D1 of the database creation holder 51, and collet dynamic characteristics, which are the dynamic characteristics of vibration in the database creation collet 51b. In this embodiment, the correspondence relationships include, in addition to the shank diameter D2 and the holder diameter D1, L2 / D2, where L2 is the extension length of the database creation tool 52 and D2 is the database creation shank diameter. In other words, the collet dynamic characteristics database 107 stores correspondence relationships between the holder diameter D1, the shank diameter D2, and L2 / D2 and the collet dynamic characteristics.

[0039] The method for acquiring the collet dynamic characteristics of the collet 51b for database creation is not limited, but is carried out as follows in this embodiment. First, the tool 52 for database creation is attached to the tool spindle 33b for database creation via the holder 51 for database creation. Then, the tip of the tool 52 is hammered on the machine tool 1 in this attached state to acquire the machine tool dynamic characteristics, which are the dynamic characteristics of vibration in the machine tool 1. Thereafter, the tool dynamic characteristics, holder dynamic characteristics, tool spindle dynamic characteristics, and machine body dynamic characteristics, which are the vibration characteristics of the machine body, for database creation are subtracted from the acquired machine tool dynamic characteristics, and the collet dynamic characteristics of the collet 51b for database creation are calculated. Note that in creating the database, the tool dynamic characteristics, holder dynamic characteristics, tool spindle dynamic characteristics, and machine body dynamic characteristics may be acquired from each model, or may be acquired by conducting a hammering test.

[0040] Furthermore, in this embodiment, the collet dynamic characteristics database 107 stores multiple correspondence relationships for each collet type, which is the shape of the collet 51b. The collet type is not limited and can be set appropriately by the user, but it is preferable to set multiple collet types that are common to multiple holders on the market. The collet type can be acquired from the holder to be analyzed by the collet type acquisition unit 109.

[0041] As an example of the correspondence relationships of collet dynamic characteristics stored in collet dynamic characteristic database 107 in this embodiment, collet dynamic characteristics for database creation corresponding to a three-dimensional coordinate space of shank diameter D2, holder diameter D1, and L2 / D2 can be plotted as shown in Fig. 4. A plurality of correspondence relationships, such as a first correspondence relationship, a second correspondence relationship, a third correspondence relationship, etc., are stored as the correspondence relationships according to the collet type.

[0042] 4-5. Collet dynamic characteristics calculation unit 108 3 calculates the collet dynamic characteristics of the analysis target by interpolating the shank diameter D2 of the tool 52 to be analyzed, the holder diameter D1 of the holder 51 to be analyzed, and the correspondence relationships stored in the collet dynamic characteristics database 107. Furthermore, in this embodiment, as the correspondence relationship for calculating the collet dynamic characteristics of the analysis target, a correspondence relationship according to the collet type of the holder 51 to be analyzed, acquired by the collet type acquisition unit 109, is extracted.

[0043] Here, we conducted confirmation tests on the relationship between the collet dynamic characteristics and the shank diameter D2, holder diameter D1, and L2 / D2, and confirmed that there is a positive linear relationship between the collet dynamic characteristics and the shank diameter D2, as shown in Figure 5(a), a positive linear relationship between the collet dynamic characteristics and the holder diameter D1, as shown in Figure 5(b), and a positive linear relationship between the collet dynamic characteristics and L2 / D2, as shown in Figure 5(c).

[0044] Based on this linear relationship, the collet dynamic characteristic calculation unit 108 performs interpolation processing to calculate the collet dynamic characteristic of the analysis target as follows: First, the shank diameter acquisition unit 110 acquires the shank diameter D2 of the tool 52 to be analyzed, the holder diameter acquisition unit 111 acquires the holder diameter D1 of the holder 51 to be analyzed, and the L2 / D2 acquisition unit 112 acquires the L2 / D2 of the tool 52 to be analyzed.

[0045] Then, if two of the acquired shank diameter D2, holder diameter D1 and L2 / D2 of the object to be analyzed match the respective values ​​for database creation that constitute the correspondence stored in the collet dynamic characteristics database 107, as shown in Figure 6(a), a point PX is plotted on the straight line PLa that shares the matching values, and two points P1 and P2 on either side of the point PX are extracted, and the value linearly interpolated between the two points is output as the collet dynamic characteristics of the object to be analyzed.

[0046] Furthermore, if one of the acquired shank diameter D2, holder diameter D1, and L2 / D2 of the object to be analyzed matches a value for database creation that constitutes a correspondence stored in the collet dynamic characteristics database 107, as shown in Figure 6(b), point PX is plotted on plane PLb that shares the matching value, and four points P1, P2, P3, and P4 that constitute a rectangle including point PX are extracted, and the value linearly interpolated between the four points is output as the collet dynamic characteristics of the object to be analyzed.

[0047] Furthermore, if none of the acquired shank diameter D2, holder diameter D1, and L2 / D2 of the object to be analyzed match the values ​​for database creation that form the correspondence stored in the collet dynamic characteristics database 107, as shown in Figure 6(c), the shank diameter D2, holder diameter D1, and L2 / D2 of the object to be analyzed are plotted as point PX in a coordinate space that shows the correspondence, and eight points P1 to P8 that form a lattice including point PX are extracted, and a value linearly interpolated between the eight points is output as the collet dynamic characteristics of the object to be analyzed.

[0048] Furthermore, if all three of the acquired shank diameter D2, holder diameter D1, and L2 / D2 match the values ​​used for database creation that constitute the correspondence stored in the collet dynamic characteristics database 107, the collet dynamic characteristics corresponding to the shank diameter D2, holder diameter D1, and L2 / D2 in the correspondence are extracted without the need for interpolation processing, and the collet dynamic characteristics are output as the calculation results.

[0049] Alternatively, it is also possible to obtain only the shank diameter D2 and holder diameter D1 to be analyzed, set L2 / D2 to a predetermined fixed value, and perform linear interpolation of the above two points or linear interpolation of the above four points.

[0050] 4-6.Analysis Department 120 3 performs a stability limit analysis of the machine tool 1 based on the tool dynamic characteristics of the analysis target, the holder dynamic characteristics of the analysis target, the tool spindle dynamic characteristics of the analysis target, and the collet dynamic characteristics of the analysis target. The tool dynamic characteristics, holder dynamic characteristics, and tool spindle dynamic characteristics of the analysis target are acquired by the above-mentioned tool dynamic characteristics acquisition unit 101, holder dynamic characteristics acquisition unit 103, and tool spindle dynamic characteristics acquisition unit 105. The collet dynamic characteristics of the analysis target are calculated by the collet dynamic characteristics calculation unit 108.

[0051] The stability limit analysis in analysis unit 120 can be performed by the receptance coupling method. That is, the tool dynamic characteristics, holder dynamic characteristics, tool spindle dynamic characteristics, and collet dynamic characteristics of the analysis target are individually acquired, and these are combined to calculate the dynamic stiffness of vibration in the entire machine tool 1, and a stability limit diagram is created based on this overall dynamic stiffness, thereby performing the stability limit analysis.

[0052] As a result of the analysis by the analysis unit 120, for example, the frequency response characteristics of the vibration compliance of the entire machine tool 1 shown in Fig. 7 are obtained, and the stability limit diagram shown in Fig. 8 is also obtained. The stability limit diagram shown in Fig. 8 is a diagram that shows the relationship between the rotational speed of the tool spindle 33b (equal to the rotational speed of the tool unit T) and the depth of cut limit. In the stability limit diagram, the upper side of the depth of cut limit is an unstable region where chatter vibration occurs, and the lower side is a stable region where chatter vibration does not occur. In the stable region, the closer to the stability limit line Q, the better the machining efficiency.

[0053] 4-7. Machining condition quality determination unit 130 The machining condition good / bad judgment unit 130 shown in Fig. 3 judges the good / bad of the machining conditions by the machine tool 1 based on the result of the stability limit analysis by the analysis unit 120. For example, in the stability limit diagram shown in Fig. 8 created by the analysis unit 120, the machining condition good / bad judgment unit 130 can judge that the machining conditions satisfy the stability conditions when the analysis result based on the machining conditions is in a stable region, and can judge that the machining conditions do not satisfy the stability conditions when the analysis result is in an unstable region.

[0054] The processing by the machining condition quality determining unit 130 will be described with reference to Fig. 9. The machining condition quality determining unit 130 inputs the machining conditions to be evaluated (step S1). The machining conditions include at least the rotation speed and cutting depth of the tool spindle 33b. Next, the machining condition quality determining unit 130 determines whether the input machining conditions satisfy the stability conditions using the results of the stability limit analysis by the analysis unit 120 (step S2). That is, it determines whether the machining conditions to be evaluated are included in the lower stable region in the stability limit diagram shown in Fig. 8.

[0055] If the stability conditions are not satisfied (S2: No), it is determined that the machining conditions should be reconsidered (Step S3). On the other hand, if the stability conditions are satisfied (S2: Yes), it is then determined whether or not to consider improving the conditions (Step S4). For example, if the machining conditions to be evaluated have a sufficient margin up to the stability limit in the stability limit diagram, it is determined that improving the conditions should be considered, such as by further increasing the cutting amount.

[0056] If there is no need to consider improved conditions (S4: No), the machining conditions to be evaluated are determined to be good, and the tool unit T to be used for machining and the stability limit diagram are output, and the process ends (step S5). On the other hand, if the stability conditions are met but improved conditions are to be considered (S4: Yes), it is determined that additional consideration will be made so that machining conditions that increase the cutting amount will satisfy the stability conditions (step S6). Then, the process ends.

[0057] 5.Effects In the support device 100 of this embodiment, the correspondence relationship stored in the collet dynamic characteristic database is the correspondence relationship between the shank diameter D2 and holder diameter D1 of the tool 52, which exhibits a high correlation with the collet dynamic characteristic, and the collet dynamic characteristic, so the collet dynamic characteristic can be obtained with high precision by using the shank diameter D2 and holder diameter D1 of the tool 52. Furthermore, even if the combination of the tool 52 and the holder 51 changes, there is no need to obtain actual measured values ​​by hammering measurement each time, which reduces the working time.

[0058] Furthermore, because the collet dynamic characteristics to be analyzed are calculated by interpolating the correspondence relationships stored in collet dynamic characteristics database 107, they can be calculated with high accuracy without excessively increasing the data density of the correspondence relationships stored in collet dynamic characteristics database 107. As a result, the effort required to create collet dynamic characteristics database 107 can be reduced, and the amount of data required for collet dynamic characteristics database 107 is small, making it easier to handle collet dynamic characteristics database 107 and improving workability. Then, by using the collet dynamic characteristics obtained in this manner, stability limit analysis of machine tool 1 can be performed easily and with high accuracy.

[0059] Furthermore, in the first embodiment, the collet dynamic characteristic database 107 stores, as the correspondence relationship, the correspondence relationship between the shank diameter D2 of the tool 52 for database creation, the holder diameter D1 of the holder 51 for database creation, L2 / D2 of the tool 52 for database creation, and the collet dynamic characteristic for database creation. By using the correspondence relationship stored in the collet dynamic characteristic database 107, the collet dynamic characteristic can be calculated with higher accuracy.

[0060] Furthermore, in the first embodiment, when the values ​​of the shank diameter D2 and holder diameter D1 of the analysis target do not match the values ​​of the shank diameter D2 and holder diameter D1 for database creation that constitute the correspondence relationship, the collet dynamic characteristic calculation unit 108 calculates the collet dynamic characteristic of the analysis target by linearly interpolating a plurality of collet dynamic characteristics for database creation that are calculated from the values ​​of the shank diameter D2 and holder diameter D1 for database creation that are close to the shank diameter D2 and holder diameter D1 of the analysis target in the correspondence relationship. This makes it possible to improve the calculation accuracy of the collet dynamic characteristic without excessively increasing the amount of data in the collet dynamic characteristic database 107.

[0061] Furthermore, in the first embodiment, the collet dynamic characteristics for database creation in the correspondence relationships stored in the collet dynamic characteristics database 107 are calculated by subtracting the tool dynamic characteristics for database creation, the holder dynamic characteristics for database creation, the tool spindle dynamic characteristics for database creation, and the machine body dynamic characteristics, which are the vibration characteristics of the machine body, from the machine tool dynamic characteristics, which are the dynamic characteristics of vibration in the machine tool 1, obtained by hammering the tool 52 for database creation in the machine tool 1 in a state where the tool 52 for database creation is attached to the tool spindle 33b for database creation via the holder 51 for database creation. This makes it possible to improve the accuracy of the correspondence relationships stored in the collet dynamic characteristics database 107 while reducing the work required to acquire the collet dynamic characteristics for database creation.

[0062] Furthermore, in the first embodiment, the tool dynamic characteristic acquisition unit 101 acquires the tool dynamic characteristics of the analysis target based on a tool model formed by modeling the tool 52 in advance, the holder dynamic characteristic acquisition unit 103 acquires the holder dynamic characteristics of the analysis target based on a holder model formed by modeling the holder 51 in advance, and the tool spindle dynamic characteristic acquisition unit 105 acquires the tool spindle dynamic characteristics of the analysis target based on a tool spindle model formed by modeling the tool spindle 33b in advance. This makes it possible to improve the accuracy of the correspondence relationships stored in the collet dynamic characteristic database 107 while reducing the work required to acquire the collet dynamic characteristics for database creation.

[0063] Furthermore, in the first embodiment, the correspondence relationship in the collet dynamic characteristic database 107 is created for each collet type, which is the form of the collet 51b, and a collet type acquisition unit 109 is provided that acquires the collet type of the collet 51b to be analyzed. Then, a collet dynamic characteristic calculation unit 108 extracts the correspondence relationship corresponding to the collet type from the collet dynamic characteristic database 107, and calculates the collet dynamic characteristic of the analysis target by interpolating it from the shank diameter D2 of the analysis target, the holder diameter D1 of the analysis target, and the extracted correspondence relationship.

[0064] Furthermore, in the first embodiment, a machining condition quality determination unit 130 is provided that determines whether the machining conditions for the machine tool 1 are good or bad based on the results of the stability limit analysis by the analysis unit 120. This makes it possible to provide support for determining optimal machining conditions.

[0065] As described above, according to this embodiment, it is possible to provide a machining condition determination support device 100 for a machine tool 1 that can reduce the work time required to calculate collet dynamic characteristics and improve workability, and can easily and accurately analyze the stability limits of the machine tool 1. [Explanation of symbols]

[0066] 1 Machine tools 33b Tool spindle 51 Holder 51b Colette 52 Tools 100 Processing condition determination support device 101 Tool dynamic characteristics acquisition section 103 Holder dynamic characteristics acquisition unit 105 Tool spindle dynamic characteristics acquisition section 107 Collet Dynamic Characteristics Database 108 Collet dynamic characteristics calculation unit 109 Collet type acquisition part 120 Analysis Department 130 Machining condition quality judgment section

Claims

1. A machining condition determination support device for a machine tool in which a tool is attached to a tool spindle provided on a machine body of the machine tool via a holder having a collet that grips the tool, a tool dynamic characteristic acquisition unit that acquires a tool dynamic characteristic, which is a dynamic characteristic of vibration in the tool to be analyzed; a holder dynamic characteristic acquisition unit that acquires a holder dynamic characteristic, which is a dynamic characteristic of vibration in the holder to be analyzed; a tool spindle dynamic characteristic acquisition unit that acquires a tool spindle dynamic characteristic, which is a dynamic characteristic of vibration in the tool spindle to be analyzed; a collet dynamic characteristics database that stores a correspondence relationship between at least a shank diameter of the tool for database creation, a holder diameter of the holder for database creation, and a collet dynamic characteristics that are dynamic characteristics of vibration in the collet for database creation; a collet dynamic characteristic calculation unit that calculates the collet dynamic characteristic of the analysis target by interpolation from the shank diameter of the tool that is the analysis target, the holder diameter of the holder that is the analysis target, and the correspondence relationship stored in the collet dynamic characteristic database; an analysis unit that performs a stability limit analysis of the machine tool based on the tool dynamic characteristics of an analysis target, the holder dynamic characteristics of an analysis target, the tool spindle dynamic characteristics of an analysis target, and the collet dynamic characteristics of an analysis target; A machining condition determination support device for a machine tool.

2. The collet dynamic characteristics database contains the following correspondence relationships: A shank diameter of the tool for creating a database; a holder diameter of the holder for creating a database; L2 / D2, where L2 is the protrusion length of the tool protruding from the holder for database creation, and D2 is the shank diameter for database creation; The collet dynamic characteristics for database creation; 2. The machining condition determination support device for a machine tool according to claim 1, wherein the correspondence relationship between the machining conditions is stored.

3. 3. The machining condition determination support device for a machine tool according to claim 1 or 2, wherein, when the values ​​of the shank diameter and the holder diameter of the object to be analyzed do not match the values ​​of the shank diameter and the holder diameter for database creation that constitute the correspondence relationship, the collet dynamic characteristic calculation unit calculates the collet dynamic characteristic of the object to be analyzed by linearly interpolating a plurality of collet dynamic characteristics for database creation calculated from the values ​​of the shank diameter and the holder diameter for database creation that are close to the shank diameter and the holder diameter of the object to be analyzed in the correspondence relationship.

4. 3. The machining condition determination support device for a machine tool according to claim 1 or 2, wherein the collet dynamic characteristics for database creation in the correspondence relationship stored in the collet dynamic characteristic database are calculated by subtracting the tool dynamic characteristics for database creation, the holder dynamic characteristics for database creation, the tool spindle dynamic characteristics for database creation, and machine body dynamic characteristics which are characteristics of vibration in the machine body from machine tool dynamic characteristics which are dynamic characteristics of vibration in the machine tool obtained by hammering the tool for database creation in the machine tool in a state where the tool for database creation is attached to the tool spindle for database creation via the holder for database creation.

5. the tool dynamic characteristic acquisition unit acquires the tool dynamic characteristic of the analysis target based on a tool model formed by modeling the tool in advance, the holder dynamic characteristic acquisition unit acquires the holder dynamic characteristic of the analysis target based on a holder model formed by modeling the holder in advance; the tool spindle dynamic characteristic acquisition unit acquires the tool spindle dynamic characteristic of the analysis target based on a tool spindle model formed in advance by modeling the tool spindle.

3. The machining condition determination support device for a machine tool according to claim 1 or 2.

6. the correspondence relationship in the collet dynamic characteristic database is created for each collet type, which is the form of the collet, a collet type acquisition unit that acquires the collet type of the collet to be analyzed, 3. The machining condition determination support device for a machine tool according to claim 1, wherein the collet dynamic characteristic calculation unit extracts the correspondence corresponding to the collet type from the collet dynamic characteristic database, and calculates the collet dynamic characteristic of the analysis target by interpolating the shank diameter of the analysis target, the holder diameter of the analysis target, and the extracted correspondence.

7. 3. The machining condition determination support device for a machine tool according to claim 1, further comprising a machining condition quality determination unit that determines whether the machining conditions for the machine tool are good or bad based on a result of the stability limit analysis by the analysis unit.

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