Display device for machine tool and display method in display device for machine tool

Abstract

To provide a display device for a machine tool and a display method in the display device for the machine tool that allow an operator to easily determine a combination of an amount of axial cut and an amount of radial cut that makes it possible to improve stability during machining and also improve operation efficiency.SOLUTION: By using machine information, tool information, material information, and model information, a plurality of types of stability limit diagrams, in which an amount of predetermined radial cut is set, are created with different values of the amount of radial cut; a combination of an amount of axial cut and the amount of radial cut, in which chatter vibration does not occur, is obtained based on the created stability limit diagrams; and an amount of power consumption in the obtained combination of the amount of axial cut and the amount of radial cut is calculated. Further, a graph showing a relation between the amount of axial cut and the amount of radial cut, which enables stable machining, is created; and the amount of power consumption for each combination of the amount of axial cut and the amount of radial cut is superimposed and displayed on the graph.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a display device provided in a machine tool such as a machining center, and a display method for the display device. [Background technology]

[0002] In recent years, manufacturers are being asked to be more environmentally conscious in order to solve global environmental problems. Therefore, not only is there a need to reduce costs and increase efficiency in machining workpieces using machine tools, but there is also a need to improve operational efficiency, such as by saving energy. Here, when considering the determination of machining conditions for cutting, for example, vibrations of machine tools and tools become an issue. Therefore, it is important to select machining conditions that can achieve both improved stability during machining, such as reduced vibrations, and improved operational efficiency, such as reduced energy consumption for the operation of the machine tool and longer tool life.

[0003] Therefore, for example, in the invention described in Patent Document 1, a stability limit diagram showing the correlation between the spindle rotational speed and the limit cutting depth of the tool at which regenerative chatter occurs is displayed superimposed on information related to the operating efficiency of the machine tool, such as the amount of energy consumed in operating the machine tool and the estimated tool life, thereby enabling the operator to easily grasp the machining conditions appropriate for achieving both of the above, i.e., the optimum rotational speed which is the appropriate spindle rotational speed, the axial cutting amount, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6802054 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the invention described in Patent Document 1, the operator must arbitrarily determine the radial depth of cut, which is one of the machining conditions. Therefore, in order to determine a combination of the axial depth of cut and the radial depth of cut that improves machining stability and also improves operation efficiency, there is a problem that a large number of trials must be repeated and the displayed information must be compared.

[0006] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a display device for a machine tool and a display method for the display device of a machine tool that enables an operator to easily determine a combination of axial and radial cutting amounts that improves stability during machining and also improves operating efficiency. [Means for solving the problem]

[0007] In order to achieve the above object, the invention described in claim 1 of the present invention is a display device that displays machining conditions for machining a workpiece in a machine tool that rotates a tool attached to a spindle to machine the workpiece, the display device comprising: a memory unit that stores tool information related to the tool and workpiece information related to the workpiece; a calculation unit that uses the tool information and the workpiece information to create multiple types of stability limit diagrams that show the correlation between the rotational speed of the spindle when a predetermined radial depth of cut is set and the axial depth of cut of the tool that generates chatter vibration, with different values ​​of the radial depth of cut, and determines a combination of the axial depth of cut and the radial depth of cut that does not generate chatter vibration based on the created stability limit diagrams, and calculates information related to operating efficiency for the determined combination; a display control unit that creates a display form in which the information related to the combination and the information related to the operating efficiency are superimposed; and a display unit that displays the created display form. The invention described in claim 2 is characterized in that, in the invention described in claim 1, the information relating to the operating efficiency is information related to the processing and includes at least one of information relating to the amount of power consumed in the processing, information relating to the processing time of the processing, and information relating to the life of the tool. The invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2, the axial cut-in amount determined based on the stability limit diagram is limited to a plurality of values ​​based on the machining dimensions of the workpiece or the dimensions of the tool, combinations of the limited axial cut-in amount and the radial cut-in amount are determined, and information related to the operating efficiency is divided into a plurality of stages according to the magnitude of the operating efficiency, and when creating the display mode, the information related to the operating efficiency corresponding to the information related to each of the combinations is displayed in a mode corresponding to the division into stages.

[0008] In addition, in order to achieve the above-mentioned object, the invention described in claim 4 of the present invention is a display method in a display device that displays machining conditions for machining a workpiece in a machine tool that rotates a tool attached to a spindle to machine the workpiece, the display method comprising the steps of: using tool information related to the tool and workpiece information related to the workpiece, creating multiple types of stability limit diagrams that show the correlation between the rotational speed of the spindle when a predetermined radial depth of cut is set and the axial depth of cut of the tool that causes chatter vibration, with different values ​​of the radial depth of cut; determining a combination of the axial depth of cut and the radial depth of cut that does not cause chatter vibration based on the created stability limit diagrams; and calculating information related to operating efficiency for the determined combination; creating a display form in which the information related to the combination and the information related to the operating efficiency are superimposed; and displaying the created display form, the display method comprising the steps of: The invention described in claim 5 is characterized in that, in the invention described in claim 4, the information relating to the operating efficiency is information related to the processing and includes at least one of information relating to the amount of power consumed in the processing, information relating to the processing time of the processing, and information relating to the life of the tool. The invention described in claim 6 is the invention described in claim 4 or 5, characterized in that in the first step, the axial cut-in amount determined based on the stability limit diagram is limited to a plurality of values ​​based on the machining dimensions of the workpiece or the dimensions of the tool, and a combination of the limited axial cut-in amount and the radial cut-in amount is determined, and in the second step, the information related to the operating efficiency is divided into a plurality of stages according to the magnitude of the operating efficiency, and the display mode is created so that the information related to the operating efficiency corresponding to the information related to each of the combinations is displayed in a manner corresponding to the division into stages. Effect of the Invention

[0009] According to the present invention, a plurality of types of stability limit diagrams showing the correlation between the rotation speed of the spindle and the axial depth of cut of the tool that generates chatter vibration when a predetermined radial depth of cut is used, with different values ​​of the radial depth of cut, a combination of the axial depth of cut and the radial depth of cut that does not generate chatter vibration is determined based on the created stability limit diagrams, information related to the operating efficiency of the determined combination is calculated, and a display mode is created in which the information related to the combination and the information related to the operating efficiency are superimposed, and the created display mode is displayed. Therefore, the operator can easily determine a combination of the axial depth of cut and the radial depth of cut that improves the stability during machining and also improves the operating efficiency. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is an explanatory diagram showing a workpiece before machining. [Diagram 2] FIG. 11 is an explanatory diagram showing the workpiece after machining. [Diagram 3] FIG. 2 is a schematic diagram showing a display device of a machining center. [Figure 4] FIG. 4 is a flowchart showing operational control relating to display on the display device. [Diagram 5] FIG. 1 is an explanatory diagram showing a tool shape when a general cutting tool and a holder are combined. [Figure 6] FIG. 6A is an explanatory diagram showing a table in which the natural frequency, the compliance at each natural frequency, and the damping rate are set as a vibration mode, and FIG. 6B is a graph showing the relationship between the natural frequency and the compliance obtained as a result of impulse vibration. [Figure 7] This is a stability limit diagram when the radial cutting depth is set to 1 / 6DC. [Figure 8] FIG. 2 is an explanatory diagram showing an example of a display mode on a display unit of a display device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A display device for a machining center and a display method for the display device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0012] Fig. 1 is an explanatory diagram showing a workpiece before machining, and Fig. 2 is an explanatory diagram showing the workpiece after machining. In this embodiment, a rectangular parallelepiped block-shaped workpiece having a left-right length L [mm], a front-to-back width W [mm], and a height H [mm] is cut to a left-to-right length L [mm] with a front-to-back width w [mm] and a depth h [mm] by cutting using an end mill 21 in a machining center.

[0013] 3 is a schematic diagram showing a display device 31 of the machining center. The display device 31 includes a storage unit 33 that stores machine information, tool information, material information, and model information as setting information 32, a calculation unit 34 that calculates a stability limit diagram, an axial cut amount, a radial cut amount, an optimum rotation speed corresponding to a combination of the axial cut amount and the radial cut amount, processing-related information, and the like, a display control unit 35 that creates a graph based on the calculation result in the calculation unit 34, and a display unit 36 ​​that displays the graph created by the display control unit 35.

[0014] A display method in the display device 31 will be described with reference to the flow chart shown in FIG. 4. FIG. 5 is an explanatory diagram showing a tool shape when a general cutting tool 51 and a holder 52 are combined. FIG. 6A is an explanatory diagram showing a table in which the natural frequency ω [rad / sec], the compliance G [μm / N] at each natural frequency, and the damping rate ζ are set as vibration modes, and FIG. 6B is a graph showing the relationship between the natural frequency ω [rad / sec] and the compliance G [μm / N] obtained by impulse vibration. FIG. 7 is a stability limit diagram when the radial cutting amount ae [mm] is set to 1 / 6 DC [mm]. FIG. 8 is an explanatory diagram showing an example of a display mode on the display unit 36 ​​of the display device 31.

[0015] First, in S-0, machine information, material information, and model information are set. Specifically, the motor rated power P [kW] and mechanical efficiency η of the auxiliary machine are set as machine information, the workpiece material type A which is the material type of the workpiece and the material shape which is the shape of the workpiece before machining are set as material information, and the after-cut shape which is the shape of the workpiece after machining and the machined surface roughness Rz are set as model information. Next, in S-1, tool information is set. Specifically, the tool diameter DC [mm], the number of blades z [pieces], and the blade length TL [mm] are set. In addition, it is desirable to set other information as the tool information, such as the tool material type, the coating material type, the holder material type, and some or all of the information on the tool shape when the blade 51 and the holder 52 are combined as shown in Fig. 5. In this embodiment, the blade length TL [mm] is longer than the depth h [mm], and the tool diameter DC [mm] is smaller than the front-rear width w [mm].

[0016] Next, in S-2, the dynamic characteristics of the machine tool and the tool to be used are set. The dynamic characteristics set here are the natural frequency ω [rad / sec], the compliance G [μm / N] at each natural frequency, and the damping factor ζ. In addition, a plurality of vibration modes are stored for the combination of the natural frequency ω [rad / sec], the compliance G [μm / N] at each natural frequency, and the damping factor ζ as shown in FIG. 6A. The natural frequency ω [rad / sec], the compliance G [μm / N], and the damping factor ζ in each vibration mode may be actual measured values ​​obtained by impulse excitation as shown in FIG. 6B. However, since the vibration mode is changed according to the type of tool or holder, it is preferable to configure it so that it is determined based on values ​​calculated from a simple physical model such as FEM calculation or beam vibration theory based on the tool information set in S-1. As another method, the vibration of cutting may be measured when performing trial cutting or product processing, and the dynamic characteristics of the machine tool and the tool may be calculated based on the measured values, and the values ​​may be set. The calculation and setting of the dynamic characteristics may be automatic or manual. Furthermore, the number of vibration modes stored in advance may be changed depending on the machining form, the type of machine tool, the tools used in machining, and the like.

[0017] Next, in S-3, the range of the spindle speed is calculated and set based on the material information and tool information set in S-1 and S-2. -1 ] is calculated using formula (1) using tool diameter DC [mm] and cutting speed VC [m / min]. Spindle speed S [min -1 ] = 1000 × V C / (π × D C ) (1) The range of cutting speed VC [m / min] is determined by the combination of the tool material, coating type, and workpiece material A used, and the allowable spindle speed S [min -1] is set. In this embodiment, a standard cutting speed VC is determined based on the above combination, and the spindle speed calculated by formula (1) is set as SMIN, which is the lower limit of the range of spindle speeds, while the spindle speed obtained by multiplying SMIN by 1.5 is set as SMAX, which is the upper limit of the range of spindle speeds. It is also possible to set the range of spindle speeds without setting a lower limit, and set the maximum rotation speed allowable by the tool as the upper limit, so that the entire range below the maximum rotation speed is included in the range. In addition, when it is not necessary to set an upper limit of the range of spindle speeds based on the combination of the workpiece material type A and the tool, it is also possible to set the maximum value of the spindle speed determined by the specifications of the motor of the machine tool as the upper limit of the range of spindle speeds, and how the range of spindle speeds is set can be changed as appropriate.

[0018] Next, in S-4, a stability limit diagram is created for a predetermined radial depth of cut ae [mm] in the range SMIN to SMAX of the spindle speed set in S-3 using the number of teeth z [pieces] of the tool information set in S-1 and the dynamic characteristics set in S-2. As the radial depth of cut ae [mm], the tool diameter DC [mm] and a value obtained by multiplying the tool diameter DC [mm] by a fraction of a positive integer less than 1, for example, 1 / 6DC [mm], 1 / 3DC [mm], 2 / 3DC [mm], 5 / 6DC [mm], etc. are adopted. In addition, the stability limit diagram is not created one by one, but is created for each radial depth of cut ae [mm] with a different value. Then, for example, as a stability limit diagram when the radial depth of cut ae [mm] is set to 1 / 6DC [mm], a stability limit diagram as shown in FIG. 7 is created. Note that, as described in Patent Document 1, there are several disclosures of a method for creating a stability limit diagram, and it is only necessary to adopt one of the conventionally known creation methods. Furthermore, there is no problem if the calculation is simplified by a method such as setting the information to be used to a constant value.

[0019] Next, in S-5, the optimal spindle speed S [min -1] and the axial cutting depth ap [mm] are calculated. In the stability limit diagram shown in FIG. 7, the spindle rotation speed corresponding to the axial cutting depth ap1 [mm] at which the axial cutting depth reaches its peak is the optimal rotation speed S1 [min -1 However, in this embodiment, taking into consideration the cutting depth h [mm], the axial cutting depth ap [mm] is limited to values ​​obtained by equally dividing h [mm] by a predetermined natural number, for example, h [mm], 1 / 2h [mm], 1 / 3h [mm], 1 / 4h [mm], etc., and the optimum rotation speed S [min -1 ] is calculated. It is of course possible to use the axial cutting depth ap1 [mm] as it is as the axial cutting depth ap [mm]. Also, due to the nature of the stability limit diagram, the peak of the axial cutting depth ap [mm] changes due to factors such as changes in the machine tool state, heat generation state, and tool wear, so a value obtained by adding a safety factor to the axial cutting depth ap1 [mm], specifically, a value obtained by multiplying the axial cutting depth ap1 [mm] by 0.8, may be used.

[0020] Next, in S-6, the power consumption [kW] is calculated for each combination of the axial cutting depth ap [mm] and radial cutting depth ae [mm] corresponding to the optimal rotation speed S calculated in S-5. In this embodiment, the power consumption [kW] is calculated from the cutting power [kW] that changes due to the axial cutting depth ap [mm] and radial cutting depth ae [mm] calculated in S-4 and S-5, and the motor rated power P [kW] of the auxiliary equipment set in S-0. The cutting power [kW] can be calculated by the following formula (2), where the cutting resistance is K [MPa]. Cutting power [kW] = Feed rate Vf × (ap × ae × K) / (60 × 10^6 × η) (2) Here, the feed rate Vf [mm / min] can be calculated by the following formula (3) using the machined surface roughness Rz set in S-0. Feed rate Vf [mm / min] = ((Rz x 8 x (DC / 2))^(1 / 2) x z x S (3) The power consumption [kW] can be calculated using the following formula (4). Power consumption [kW] = cutting power + auxiliary motor rated power P (4) The cutting resistance K [MPa] may be stored in advance as a table in association with the combination of the tool and the workpiece material type set as the material information or the tool information, and may be determined from the table. The power consumption [kW] may be calculated by taking into consideration the power consumption due to the movement of the machine axis and the change in power consumption due to the acceleration and deceleration of the machine movement.

[0021] Next, in S-7, the power consumption [kWh] for each combination of the axial cutting depth ap [mm] and the radial cutting depth ae [mm] is calculated based on the power consumption [kW] calculated in S-6. In this embodiment, the power consumption [kWh] is the product of the power consumption [kW] and the power usage time [hours], and the power usage time [hours] is the machining time [hours]. The machining time [hours] can be calculated from the left-right length L [mm] shown in FIG. 2, the feed rate Vf [mm / min] calculated in S-6, and the number of cuttings [times] required to cut the machining area shown in FIG. 2, and the number of cuttings [times] can be calculated by the following formula (5). Number of cuts [times] = (h / ap) × (w / ae) (5) In addition, the number of cutting times [times] calculated using formula (5) can be used to calculate the processing time [hours] using the following formula (6). Machining time [hours] = (L / Vf) × 60 × number of cuts (6) Furthermore, using the processing time [hours] calculated using equation (6), the power consumption [kWh] can be calculated using the following equation (7). Power consumption [kWh] = power consumption x machining time (7) In addition, there is no problem in calculating the power usage time [hours] by taking into account not only the processing time [hours] but also time when no processing is being performed, such as time required to move to the next processing step.

[0022] Next, in S-8, a graph is created showing the relationship between the axial cutting depth ap [mm] and the radial cutting depth ae [mm] that allows stable machining. In this embodiment, since the axial cutting depth ap [mm] is limited as described above, a graph like that shown in FIG. 8 is created.

[0023] Next, in S-9, the power consumption [kWh] for each combination of the axial cutting depth ap [mm] and the radial cutting depth ae [mm] is displayed superimposed on the graph created in S-8. For this display, the power consumption [kWh] calculated in S-7 is divided into five stages, and the power consumption [kWh] is displayed in ascending order of power consumption [kWh] with the symbols ◎, ○, △, □, and ×, as shown in Fig. 8. Note that the method of displaying the power consumption [kWh] in stages may be a display using a color map, a display using shading, a bubble chart, a 3D graph, or any other method other than the display using the above symbols. Next, in S-10, the combination of the axial cutting depth ap [mm] and radial cutting depth ae [mm] that results in the smallest power consumption [kWh] is displayed on the graph created in S-8. In Figure 8, the combination of the axial cutting depth ap [mm] and radial cutting depth ae [mm] that results in the smallest power consumption [kWh] is displayed with a star symbol.

[0024] Finally, in S-11, the axial cutting depth ap [mm], radial cutting depth ae [mm], and optimal rotation speed S [min -1 ] are displayed on a graph. Optimum rotation speed S[min -1] is the value at which chatter vibration does not occur for the axial depth of cut ap [mm] and power consumption is the smallest in the stability limit diagram for the radial depth of cut ae [mm]. In Fig. 8, the combination with the smallest power consumption is indicated with a star symbol, and the cutting conditions for the axial depth of cut ap: h [mm], radial depth of cut ae: 1 / 6DC [mm], and recommended rotation speed: S1 [min -1 ] and power consumption: P1 [kWh] are shown as the first candidate on the graph. In addition, the axial cutting depth ap [mm], radial cutting depth ae [mm], and optimal rotation speed S [min -1 ], as well as the axial cutting depth ap [mm], radial cutting depth ae [mm], and optimal rotation speed S [min -1 ] and power consumption [kWh] may be displayed side by side. That is, as shown in FIG. 8, the second candidate is the axial cutting depth ap: 1 / 3h [mm], the radial cutting depth ae: 1 / 2DC [mm], the recommended rotation speed: S3 [min -1 ], power consumption: P3 [kWh] may also be displayed.

[0025] According to the display device 31 and the display method thereof having the above-mentioned configuration, a plurality of types of stability limit diagrams showing the correlation between the rotation speed of the spindle and the axial cutting amount ap [mm] of the tool that generates chatter vibration when a predetermined radial cutting amount ae [mm] is set are created by varying the value of the radial cutting amount ae [mm] using the tool information, material information (workpiece information), and model information (workpiece information), and a combination of the axial cutting amount ap [mm] and the radial cutting amount ae [mm] that does not generate chatter vibration is obtained based on the created stability limit diagram, and the power consumption [kWh] for the obtained combination of the axial cutting amount ap [mm] and the radial cutting amount ae [mm] is calculated. Furthermore, a graph showing the relationship between the axial cutting amount ap [mm] and the radial cutting amount ae [mm] that allows stable machining is created, and the power consumption [kWh] for each combination of the axial cutting amount ap [mm] and the radial cutting amount ae [mm] is displayed superimposed on the graph. Therefore, the operator can easily determine a combination of the axial cutting depth ap [mm] and the radial cutting depth ae [mm] that improves stability during processing and also improves operating efficiency.

[0026] In addition, the axial cutting depth ap [mm] is limited to a value obtained by equally dividing h [mm] by a predetermined natural number, for example, h [mm], 1 / 2h [mm], 1 / 3h [mm], 1 / 4h [mm], etc., and the optimal rotation speed S [min -1 ] is calculated, and a combination of the axial cutting amount ap [mm] and the radial cutting amount ae [mm] is obtained, and the power consumption [kWh] for each combination of the axial cutting amount ap [mm] and the radial cutting amount ae [mm] is displayed, so that even in a case where an optimal combination of the axial cutting amount ap [mm] and the radial cutting amount ae [mm] cannot be selected due to machining limitations such as interference between the tool and the workpiece or jig, the operator can easily grasp the most effective machining conditions within the limitations. Therefore, the display device 31 and the display method in the display device 31 can be made even more user-friendly.

[0027] Furthermore, the axial cutting depth ap [mm], radial cutting depth ae [mm], and optimal rotation speed S [min -1 ], as well as the axial cutting depth ap [mm], radial cutting depth ae [mm], and optimal rotation speed S [min -1 ] and power consumption [kWh] are also displayed side by side. Here, in the case where the front-rear width w [mm] during machining is larger than the tool diameter DC [mm] as in this embodiment, if the front-rear width w = 4 / 3DC [mm], if the power consumption [kWh] is not displayed, it is a general idea to select the axial cutting amount 1 / 2h [mm] and the radial cutting amount 1 / 3DC [mm] and set the number of cuttings to 8 [times]. However, it is more advantageous in terms of power consumption [kWh] to select the axial cutting amount 1 / 3h [mm] and the radial cutting amount 1 / 2DC [mm], although the number of cuttings is 9 [times]. In this way, depending on the conditions such as the machining dimensions, there may be a combination of the axial cutting amount ap [mm] and the radial cutting amount ae [mm] that is more effective in terms of power consumption [kWh] even if the number of cuttings [times] increases. Therefore, as described above, the axial cutting amount ap [mm], radial cutting amount ae [mm], and optimal rotation speed S [min -1 By also displaying the values ​​of the time spent on the job [kWh] and the amount of power consumed [kWh], it is possible to provide the operator with information that can be advantageous to him / her, making the display device 31 and the display method on the display device 31 extremely easy to use.

[0028] The configuration of the display device of the machine tool of the present invention and the display method in the display device are not limited to the above-described embodiments, and the configuration of the entire machine tool, as well as the specific contents of the configuration of the display device and the display method, can be appropriately modified as necessary without departing from the spirit of the present invention.

[0029] For example, in the above embodiment, the amount of power consumption is displayed as information related to operating efficiency, but instead of the amount of power consumption, the processing time, tool life, etc. may be calculated for each combination of axial cutting amount and radial cutting amount as information related to operating efficiency, and displayed superimposed on a graph showing the relationship between the axial cutting amount and the radial cutting amount. In addition, although the above embodiment is directed to a display device for a machining center, the display device can also be suitably adopted for a machine tool other than a machining center, so long as the machine tool rotates a tool attached to a spindle to machine a workpiece. For example, the display device can be applied to a lathe with a rotating tool attached to a turret, a multi-tasking machine with a turning spindle and a rotating tool spindle, a cutting processing system with a rotating tool spindle attached to a robot hand, etc. [Explanation of symbols]

[0030] 31 display device, 32 setting information, 33 storage unit, 34 calculation unit, 35 display control unit, 36 display unit.

Claims

1. A display device that displays machining conditions for machining a workpiece in a machine tool that rotates a tool attached to a spindle, comprising: A storage unit that stores tool information related to the tool and workpiece information related to the workpiece; a calculation unit that uses the tool information and the workpiece information to create a plurality of types of stability limit diagrams showing a correlation between the rotation speed of the spindle and the axial cut-in amount of the tool at which chatter vibration occurs when a predetermined radial cut-in amount is set, by varying the value of the radial cut-in amount, determines a combination of the axial cut-in amount and the radial cut-in amount at which chatter vibration does not occur based on the created stability limit diagrams, and calculates information related to operation efficiency for the determined combination; a display control unit that creates a display mode in which the information related to the combination and the information related to the operating efficiency are superimposed; A display device for a machine tool, comprising: a display unit for displaying the created display mode.

2. The display device for a machine tool as described in claim 1, characterized in that the information relating to the operating efficiency is information related to the machining and includes at least one of information relating to the amount of power consumed in the machining, information relating to the machining time of the machining, and information relating to the life of the tool.

3. The axial cutting amount calculated based on the stability limit diagram is limited to a plurality of values ​​based on the machining dimensions of the workpiece or the dimensions of the tool, and a combination of the limited axial cutting amount and the radial cutting amount is calculated; The display device according to claim 1 or 2, characterized in that the information relating to the operating efficiency is divided into a plurality of stages according to the magnitude of the operating efficiency, and when creating the display mode, the information relating to the operating efficiency corresponding to the information relating to each of the combinations is displayed in a mode corresponding to the division into stages.

4. A display method for a display device that displays machining conditions for machining a workpiece in a machine tool that rotates a tool attached to a spindle, comprising the steps of: a first step of creating a plurality of types of stability limit diagrams, each showing a correlation between a rotation speed of the spindle and an axial depth of cut of the tool at which chatter vibration occurs when a predetermined radial depth of cut is set, by varying the value of the radial depth of cut, using tool information related to the tool and workpiece information related to the workpiece, determining a combination of the axial depth of cut and the radial depth of cut at which chatter vibration does not occur based on the created stability limit diagrams, and calculating information related to operating efficiency for the determined combination; a second step of creating a display form in which the information related to the combination and the information related to the operating efficiency are superimposed; and a third step of displaying the created display mode.

5. A display method on a display device of a machine tool as described in claim 4, characterized in that the information relating to the operating efficiency is information related to the machining and includes at least one of information relating to the amount of power consumed in the machining, information relating to the machining time of the machining, and information relating to the life of the tool.

6. In the first step, the axial cutting amount calculated based on the stability limit diagram is limited to a plurality of values ​​based on a machining dimension of the workpiece or a dimension of the tool, and a combination of the limited axial cutting amount and the radial cutting amount is calculated; A display method for a display device of a machine tool as described in claim 4 or 5, characterized in that in the second step, the information relating to the operating efficiency is divided into a plurality of stages according to the magnitude of the operating efficiency, and the display mode is created so that the information relating to the operating efficiency corresponding to the information relating to each of the combinations is displayed in a mode corresponding to the division into stages.

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