阅读说明：本技术 机床以及放电加工装置 (Machine tool and electric discharge machining device ) 是由 后藤广树 斧原圣史 今城胜治 铃木巨生 柳泽隆行 于 2019-09-17 设计创作，主要内容包括：机床具备对工件(3)的加工面(3a)供给切削油而对加工面(3a)进行加工的加工部(10),机床被构成为具备：光传感器主体部(22),将从扫频光源(31a)输出的光分为照射于工件(3)的照射光和参照光,将照射光照射于工件(3),并且检测作为被工件(3)反射的照射光的反射光与参照光的干涉光的峰值频率,基于峰值频率测定从机床至加工面(3a)的距离,其中该扫频光源(31a)输出频率周期性变化的光；以及形状计算部(75),基于由光传感器主体部(22)测定出的距离计算工件(3)的形状。(A machine tool is provided with a processing unit (10) that supplies cutting oil to a processing surface (3a) of a workpiece (3) and processes the processing surface (3a), and is configured to be provided with: an optical sensor main body (22) that divides light output from a sweep light source (31a) into irradiation light and reference light that are irradiated onto a workpiece (3), irradiates the workpiece (3) with the irradiation light, detects a peak frequency of interference light that is reflected light of the irradiation light reflected by the workpiece (3) and the reference light, and measures the distance from a machine tool to a processing surface (3a) on the basis of the peak frequency, wherein the sweep light source (31a) outputs light whose frequency changes periodically; and a shape calculation unit (75) that calculates the shape of the workpiece (3) on the basis of the distance measured by the optical sensor main body unit (22).)

1. A machine tool including a processing unit that supplies cutting oil to a processing surface of a workpiece to process the processing surface, the machine tool comprising:

an optical sensor unit that divides light output from a sweep light source that outputs light whose frequency changes periodically into irradiation light that irradiates the workpiece and reference light, irradiates the irradiation light onto the workpiece, detects a peak frequency of interference light that is reflected light of the irradiation light reflected by the workpiece and the reference light, and measures a distance from the machine tool to the processing surface based on the peak frequency; and

and a shape calculation unit that calculates the shape of the workpiece based on the distance measured by the optical sensor unit.

2. The machine tool of claim 1,

the interference light includes 1 st interference light and 2 nd interference light, the 1 st interference light is interference light of reflected light from the machining surface of the workpiece and the reference light, the 2 nd interference light is interference light of reflected light from the cutting oil and the reference light,

the optical sensor unit calculates a distance from the machine tool to the machining surface based on a peak frequency of the 1 st interference light and a peak frequency of the 2 nd interference light.

3. The machine tool of claim 2,

the photosensor section distinguishes a peak frequency of the 1 st interference light from a peak frequency of the 2 nd interference light based on a magnitude of a frequency.

4. The machine tool of claim 3,

the optical sensor unit measures a distance from the machine tool to the machining surface based on a distance from the machine tool to the cutting oil and a thickness of the cutting oil.

5. The machine tool of claim 1,

the processing unit includes:

a tool holding unit that holds a machining tool for machining the machining surface;

a head main body portion that holds the cutter holding portion; and

a head driving unit that changes a position of the head main body relative to a table on which the workpiece is placed,

wherein the shape calculating section calculates the shape of the workpiece based on the position of the head main body section changed by the head driving section and the distance measured by the optical sensor section.

6. The machine tool of claim 1,

the processing unit includes:

a tool holding unit that holds a machining tool for machining the machining surface; and

a head main body portion that holds the cutter holding portion,

wherein a part of the photosensor section is attached to the head main body section.

7. The machine tool of claim 6,

as a part of the optical sensor section, a sensor head section having a condensing optical element is attached to the head main body section.

8. The machine tool of claim 7,

comprises a table having a surface on which the workpiece is placed,

wherein the sensor head portion is attached to an outer peripheral surface of the plurality of outer peripheral surfaces of the head main body portion, the outer peripheral surface being opposed to a surface on which the workpiece is placed.

9. The machine tool of claim 1,

the processing unit includes:

a tool holding unit that holds a machining tool for machining the machining surface; and

a head main body portion that holds the cutter holding portion,

wherein a part of the optical sensor portion is held by the tool holding portion.

10. The machine tool of claim 9,

as a part of the optical sensor portion, a sensor head portion having a condensing optical element is held by the tool holding portion.

11. The machine tool of claim 1,

the machining unit includes a tool storage unit that stores a plurality of machining tools for machining the machining surface,

wherein a portion of the optical sensor part is stored in the tool storage part.

12. The machine tool of claim 1,

the processing unit includes:

a tool holding unit that holds a machining tool for machining the machining surface; and

a head main body portion that holds the cutter holding portion,

wherein the optical sensor portion is held by the tool holding portion.

13. The machine tool of claim 1,

the machining unit includes a tool storage unit that stores a plurality of machining tools for machining the machining surface,

wherein the optical sensor part is stored in the tool storage part.

14. The machine tool of claim 1,

the processing unit includes:

a tool holding unit that holds a machining tool for machining the machining surface; and

a head main body portion that holds the cutter holding portion,

wherein a communication cable for outputting information including the distance measured by the optical sensor unit to the outside is led out through the inside of the head main body unit.

15. The machine tool of claim 1,

the machining unit includes a cutting oil nozzle for supplying the cutting oil to the machining surface.

16. A machine tool including a processing unit that supplies machining oil to a machining surface of a workpiece to machine the machining surface, the machine tool comprising:

an optical sensor unit that divides light output from a swept frequency light source that outputs light whose frequency varies periodically in 1 frequency band into irradiation light that irradiates the workpiece and reference light, irradiates the irradiation light onto the workpiece, detects a peak frequency of interference light that is reflected light of the irradiation light reflected by the workpiece and the reference light, and measures a distance from the machine tool to the processing surface based on the peak frequency; and

and a shape calculation unit that calculates the shape of the workpiece based on the distance measured by the optical sensor unit.

17. An electric discharge machining apparatus including a machining unit that machines a machining surface of a workpiece immersed in machining oil, the electric discharge machining apparatus comprising:

an optical sensor unit that divides light output from a sweep light source that outputs light whose frequency varies periodically in 1 frequency band into irradiation light that irradiates the workpiece and reference light, irradiates the irradiation light onto the workpiece, detects a peak frequency of interference light that is reflected light of the irradiation light reflected by the workpiece and the reference light, and measures a distance from the electric discharge machining apparatus to the machining surface based on the peak frequency; and

and a shape calculation unit that calculates the shape of the workpiece based on the distance measured by the optical sensor unit.

Technical Field

The present invention relates to a machine tool and an electric discharge machining apparatus for machining a machined surface of a workpiece.

Background

Conventionally, the following machine tools are known: an object is machined and the surface shape of a machined surface of the machined object is measured (see patent document 1). In the machine tool described in patent document 1, the surface shape of the machined surface is measured from the change in the intensity of the reflected light.

In a state where cutting oil applied during machining adheres to a machined surface, the optical sensor cannot receive appropriate reflected light, and therefore, in the machine tool described in patent document 1, the cutting oil adhering to the machined surface is removed by purging before the shape is measured.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-36083

Disclosure of Invention

Technical problem to be solved by the invention

However, when it is desired to completely remove the cutting oil, it takes a long time to perform the purging. In order to shorten the measurement time of the shape, it is desirable to be able to measure the surface shape of the machined surface even in a state where the cutting oil remains on the machined surface.

The present invention has been made to solve the above-described technical problem, and an object of the present invention is to provide a machine tool capable of measuring the shape of a workpiece even when cutting oil remains on the machined surface of the workpiece.

Means for solving the problems

A machine tool according to the present invention includes a machining unit that supplies cutting oil to a machining surface of a workpiece to machine the machining surface, and includes: an optical sensor unit that separates light output from a sweep light source that outputs light whose frequency changes periodically into irradiation light that irradiates a workpiece and reference light, irradiates the workpiece with the irradiation light, detects a peak frequency of interference light that is interference light between reflected light of the irradiation light reflected by the workpiece and the reference light, and measures a distance from a machine tool to a processing surface based on the peak frequency; and a shape calculation unit that calculates the shape of the workpiece based on the distance measured by the optical sensor unit.

Effects of the invention

The machine tool of the present invention can measure the shape of a workpiece even when cutting oil remains on the machining surface of the workpiece.

Drawings

Fig. 1 is a configuration diagram showing a machine tool according to embodiment 1.

Fig. 2 is a configuration diagram showing the optical sensor unit 20 according to embodiment 1.

Fig. 3 is an explanatory diagram showing an example of the sweep light.

Fig. 4 is an explanatory view showing reflection of the irradiation light on the machining surface 3a and reflection of the irradiation light on the cutting oil.

Fig. 5 is a hardware configuration diagram showing a computer when the distance calculating unit 40 is implemented by software, firmware, or the like.

Fig. 6 is a configuration diagram showing a control unit 50 of a machine tool according to embodiment 1.

Fig. 7A shows an initial distance L, which is a distance from the distal end 21a of the sensor head 21 to the position of the machined surface 3a in a state where the machined surface 3a is not machined₀Fig. 7B is an explanatory view showing the distance L from the front end 21a of the sensor head 21 to the position of the machined surface 3a in the state where the machined surface 3a is machined.

Fig. 8 is a hardware configuration diagram showing hardware of a part of the control unit 50.

Fig. 9 is a hardware configuration diagram of a computer when a part of the control unit 50 is implemented by software, firmware, or the like.

Fig. 10 is a flowchart showing a flow of the machine tool when measuring the shape of the machining surface 3a of the workpiece 3.

Fig. 11 is a flowchart showing a process of calculating the distance in the sensor main body portion 22.

Fig. 12 is an explanatory diagram showing an example of a frequency domain signal.

Fig. 13 is a configuration diagram showing a machine tool according to embodiment 2.

Fig. 14 is a structural diagram showing a sensor head 21b according to embodiment 2.

Fig. 15 is a configuration diagram showing a machine tool according to embodiment 3.

Fig. 16 is a configuration diagram showing a machine tool according to embodiment 4.

Fig. 17 is a partially enlarged view showing a machine tool according to embodiment 4.

Fig. 18 is a configuration diagram showing a machine tool according to embodiment 5.

Reference numerals

1: a work table; 2. 2': a vise; 3: a workpiece; 3 a: processing the dough; 4: processing a tank; 5: discharging oil; 10: a processing section; 11: a machining head; 11 a: a head main body portion; 11 b: a spindle (tool holding section); 11 c: an outer peripheral surface; 12: processing a cutter; 13: a head driving section; 14: a cutting oil nozzle; 15: an electrode; 15 a: a front end portion; 20: a photosensor section; 21. 21 b: a sensor head; 21 a: a front end; 22: a sensor main body portion; 23: a light transmitting section; 25: a communication cable; 31: a sweep frequency light output section; 31 a: sweeping a light source; 32: a light splitting part; 33: an optical coupler; 34: a circulator (circulator); 35: a light-condensing optical element; 36: a light interference section; 37: an optical interferometer; 38: a photodetector; 39: an A/D converter; 40: a distance calculation unit; 50: a control unit; 61: a memory; 62: a processor; 71: an input section; 72: a storage device; 73: a coordinate setting unit; 74: a cutting oil supply section; 75: a shape calculating section; 76: an error calculation unit; 77: a display processing unit; 78: a three-dimensional data conversion unit; 79: a display; 81: a coordinate setting circuit; 82: a cutting oil supply circuit; 83: a shape calculation circuit; 84: an error calculation circuit; 85: a three-dimensional data conversion circuit; 91: a memory; 92: a processor; 100. 102: a tool storage section; 101: a tool changing section; 110: a housing; 111. 112, 112: an aspherical lens; 113: a mirror; 114: an installation part; 121. 122: an electrical connection portion.

Detailed Description

In the following, embodiments for carrying out the present invention will be described with reference to the accompanying drawings in order to explain the present invention in more detail.

Embodiment 1.

Fig. 1 is a configuration diagram showing a machine tool according to embodiment 1. In fig. 1, a table 1 is a base on which a workpiece 3 to be processed is placed. The vise 2 is a fixture for fixing the workpiece 3 without moving it when the workpiece 3 is machined. The workpiece 3 corresponds to a metal or the like to be processed by the processing portion 10 on the processing surface 3 a. In embodiment 1, for simplicity of explanation, the processing surface 3a before being processed by the processing target portion 10 is a flat surface.

The processing unit 10 includes: a machining head 11, a machining tool 12, a head driving section 13, and a cutting oil nozzle 14. The machining unit 10 supplies cutting oil to the machining surface 3a of the workpiece 3 to machine the machining surface 3 a.

The machining head 11 includes a head main body 11a and a spindle 11b as a tool holder. The head body 11a is a metal structure for supporting the spindle 11 b. The spindle 11b is a metal shaft-like member that incorporates a chuck device, not shown, for detachably holding the machining tool 12 and is rotationally driven while holding the machining tool 12. A sensor head 21, which is a part of the optical sensor unit 20, is attached to the head body 11 a.

The machining tool 12 is a cutting tool for cutting the machining surface 3a of the workpiece 3 by a rotational operation, and is a cutting tool for metal machining such as a milling cutter, an end mill, a drill, or a tap.

The head driving unit 13 is a driving mechanism that relatively changes the position of the head main body 11a with respect to the processing surface 3a based on a control signal output from the control unit 50. The direction of change in the position of the head main body 11a by the head driving unit 13 is the x-axis direction, the y-axis direction, or the z-axis direction shown in fig. 1.

The cutting oil nozzle 14 is a nozzle for applying cutting oil to the machining surface 3a of the workpiece 3 when receiving a supply command of cutting oil from the control unit 50.

The optical sensor unit 20 includes a sensor head 21, a sensor body 22, and an optical transmission unit 23. The optical sensor unit 20 is a sensor for calculating a distance from the distal end 21a of the sensor head 21 to the processing surface 3a processed by the processing unit 10.

The sensor head portion 21 is attached to an outer peripheral surface 11c facing the table 1 among a plurality of outer peripheral surfaces of the head main body portion 11 a. The sensor head 21 irradiates the irradiation light output from the sensor body 22 toward the machined surface 3a, and receives reflected light including reflected light as the irradiation light reflected by the machined surface 3a and reflected light as the irradiation light reflected by the cutting oil. The sensor head portion 21 outputs the received reflected light to the sensor main body portion 22.

The sensor main body 22 calculates the distance from the front end 21a of the sensor head 21 to the processing surface 3a, and outputs distance information indicating the calculated distance to the control unit 50.

The light transmission unit 23 is a transmission path for light from the sensor main body 22 to the sensor head 21 and light from the sensor head 21 to the sensor main body 22, and is formed of an optical fiber. In addition, although the machine tool according to embodiment 1 is provided with the light transmission unit 23, the light transmission unit 23 is not necessarily provided. In the case where the light transmitting portion 23 is not provided, light can be transmitted through a space.

The control unit 50 outputs a control signal indicating the movement position of the head main body 11a to the head driving unit 13, and outputs a supply command of the cutting oil to the cutting oil nozzle 14. The control unit 50 calculates the shape of the processing surface 3a based on the position of the head body 11a changed by the head driving unit 13 and the distance indicated by the distance information output from the sensor body 22.

Next, the structure of the photosensor section 20 will be described with reference to fig. 2. Fig. 2 is a configuration diagram showing the optical sensor unit 20 according to embodiment 1. As shown in fig. 2, the optical sensor unit 20 includes a sweep light output unit 31, a spectroscopic unit 32, an optical interference unit 36, an analog-to-digital converter (hereinafter referred to as "a/D converter") 39, and a distance calculation unit 40.

In fig. 2, the sweep light output unit 31 includes a sweep light source 31a, and the sweep light source 31a outputs sweep light whose frequency changes with the passage of time in 1 band. 1 frequency band from the lowest frequency f_minTo the highest frequency f_maxIn the wavelength band of. The sweep light output unit 31 outputs the sweep light to the spectroscopic unit 32. Fig. 3 is an explanatory diagram showing an example of the swept-frequency light. Swept-frequency light is a frequency that goes from the lowest frequency f with time_minTo the highest frequency f_maxOf the signal of (1). When the frequency of the swept light reaches the maximum frequency f_maxWhile the frequency is temporarily returned to the lowest frequency f_minThen the frequency is again from the lowest frequency f_minTo the highest frequency f_max. The swept-frequency light is also sometimes referred to as chirp light.

The spectroscopic unit 32 includes an optical coupler 33 and a circulator 34. The optical coupler 33 is a spectroscopic element that separates the sweep light output from the sweep light output unit 31 into reference light and irradiation light. The optical coupler 33 outputs the reference light to the optical interferometer 37, and outputs the irradiation light to the circulator 34.

The circulator 34 outputs the irradiation light output from the optical coupler 33 to the condensing optical element 35 of the sensor head 21 via the light transmission unit 23. The circulator 34 outputs the reflected light output from the condensing optical element 35 to the optical interferometer 37.

The sensor head 21 has a light-collecting optical element 35. The condensing optical element 35 condenses the irradiation light output from the circulator 34 on the processing surface 3 a. Specifically, the condensing optical element 35 includes two aspherical lenses, and after the light output from the circulator 34 is made into parallel light by the aspherical lens of the previous stage, the light is condensed by the aspherical lens of the subsequent stage and irradiated on the processing surface 3 a.

Fig. 4 is an explanatory view showing reflection of the irradiation light on the machining surface 3a and reflection of the irradiation light on the cutting oil. As shown in fig. 4, the irradiation light output from the condensing optical element 35 is reflected not only by the processing surface 3a but also by the cutting oil.

Returning to fig. 2, the light-condensing optical element 35 receives reflected light including reflected light from the machining surface 3a and reflected light from the cutting oil. The condensing optical element 35 outputs the received reflected light to the circulator 34 via the light transmission section 23. The circulator 34 outputs the reflected light output from the condensing optical element 35 to the optical interferometer 37.

The optical interference unit 36 includes an optical interferometer 37 and a photodetector 38. The light interference unit 36 generates interference light of the reflected light received by the sensor head 21 and the reference light, converts the interference light into an electric signal, and outputs the electric signal to the a/D converter 39.

The reflected light output from the circulator 34 and the reference light output from the optical coupler 33 are incident on the optical interferometer 37. The optical interferometer 37 generates interference light of the reflected light and the reference light. As described above, since the reflected light from the workpiece includes the reflected light from the machining surface 3a and the reflected light from the cutting oil, the interference light generated by the optical interferometer 37 also includes the machining surface interference light (1 st interference light) which is the interference light between the reflected light from the machining surface 3a and the reference light, and the cutting oil interference light (2 nd interference light) which is the interference light between the reflected light from the cutting oil and the reference light.

The photodetector 38 detects interference light including the machining surface interference light and the cutting oil interference light, and converts the interference light into an electric signal. The photodetector 38 outputs the electrical signal to an a/D converter 39.

The a/D converter 39 converts the electric signal output from the photodetector 38 from an analog signal to a digital signal, and outputs the digital signal to the distance calculation unit 40.

The distance calculation unit 40 converts the digital signal output from the a/D converter 39 into a signal in the frequency domain, analyzes the frequency of the interference light generated by the light interference unit 36, and calculates the distance L from the front end 21a of the sensor head 21 to the processing surface 3a based on the analysis result of the frequency. Specifically, the distance calculation unit 40 distinguishes the frequency of the machining surface interference light from the frequency of the cutting oil interference light, and calculates the distance L from the distal end 21a of the sensor head 21 to the machining surface 3a based on the frequency of the machining surface interference light. The distance calculation unit 40 outputs distance information indicating the calculated distance L to the shape calculation unit 75 of the control unit 50.

The distance calculating unit 40 is realized by, for example, a distance calculating circuit not shown. The distance calculation Circuit corresponds to, for example, a single Circuit, a composite Circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

Note that, although the distance calculating unit 40 is realized by a distance calculating circuit as dedicated hardware, the present invention is not limited to this, and may be realized by software, firmware, or a combination of software and firmware. The software or firmware is stored as a program in the memory of the computer. The term "computer" means hardware for executing a program, and corresponds to, for example, a CPU (Central Processing Unit), a Central Processing Unit, a Processing Unit, an arithmetic Unit, a microprocessor, a microcomputer, a Processor, or a DSP (Digital Signal Processor). Fig. 5 is a hardware configuration diagram of a computer when the distance calculation unit 40 is implemented by software, firmware, or the like. When the distance calculating unit 40 is implemented by software, firmware, or the like, a program for causing a computer to execute the processing flow of the distance calculating unit 40 is stored in the memory 61. The processor 62 of the computer then executes the program stored in the memory 61.

Next, the configuration of the control unit 50 will be described with reference to fig. 6. Fig. 6 is a configuration diagram showing a control unit 50 of a machine tool according to embodiment 1.

The input unit 71 receives a supply instruction of cutting oil from a user, a machining instruction of the workpiece 3 from a user, a shape measurement instruction of the workpiece 3 from a user, and the like. The input unit 71 is implemented by a human-machine interface such as an operation button.

The storage device 72 stores shape data indicating the target shape of the processing surface 3 a. The shape data includes data indicating (x, y) coordinates of a plurality of points on the processing surface 3a and data indicating depth information d of the plurality of points. The depth information d is information indicating the depth of cut from the plane of the processing surface 3a in a state in which processing has not been performed. The target shape is a shape of the processed surface 3a after processing, and is, for example, a shape designed by a user. The storage device 72 is implemented by, for example, a hard disk.

When an instruction to machine the workpiece 3 or an instruction to measure the shape of the workpiece 3 is received by the input unit 71, the coordinate setting unit 73 acquires the shape data stored in the storage device 72. The coordinate setting unit 73 generates a control signal indicating the movement position of the head main body 11a based on the acquired shape data. The movement position of the head main body portion 11a is expressed by (x, y) coordinates.

When the input unit 71 receives the machining instruction for the workpiece 3, the control signal generated by the coordinate setting unit 73 includes depth information d of a point expressed by (x, y) coordinates. The head driving unit 13 moves the head main body 11a in the z-axis direction based on the depth information d after moving the head main body 11a to the movement position indicated by the control signal generated by the coordinate setting unit 73.

On the other hand, when the input section 71 receives the instruction to measure the shape of the workpiece 3, the control signal generated by the coordinate setting section 73 includes, for example, information to move the position of the head main body 11a in the z-axis direction to the reference position. The reference position is a position of the head main body 11a in the z-axis direction when the shape of the processing surface 3a is measured, and is known in the coordinate setting unit 73. As shown in fig. 7A, when the head body portion 11a is present at the reference position, the distance from the front end 21a of the sensor head portion 21 to the position of the processing surface 3a is L₀Hereinafter, L will be described₀Referred to as the initial distance. Initial distance L₀The coordinate setting unit 73 is also known. Fig. 7A shows an initial distance L, which is a distance from the distal end 21a of the sensor head 21 to the position of the machined surface 3a in a state where the machined surface 3a is not machined₀The description of the drawings. Fig. 7B is an explanatory diagram showing the distance L from the front end 21a of the sensor head 21 to the position of the machined surface 3a in a state where the machined surface 3a is machined.

Returning to fig. 6, the head driving unit 13 that has received the control signal moves the head main body 11a to the movement position indicated by the control signal generated by the coordinate setting unit 73, and then moves the head main body 11a in the z-axis direction so that the position of the head main body 11a in the z-axis direction is the reference position.

When the input unit 71 receives the instruction to measure the shape of the workpiece 3 and the control signal is transmitted to the head driving unit 13, the coordinate setting unit 73 transmits a synchronization signal, which is a trigger for emitting the sweep light from the sweep light source 31a, to the sensor main body 22. Further, when the input section 71 receives an instruction to measure the shape of the workpiece 3, the coordinate setting section 73 sets the shape data and the initial distance L₀Output to a shape meterThe calculation unit 75 and the error calculation unit 76.

When receiving the instruction to supply the cutting oil from the input unit 71, the cutting oil supply unit 74 outputs a cutting oil supply instruction to the cutting oil nozzle 14, the cutting oil supply instruction indicating that the cutting oil is applied to the machining surface 3 a.

The shape calculation unit 75 calculates the initial distance L output from the coordinate setting unit 73₀The difference from the distance L indicated by the distance information output from the distance calculation unit 40 is defined as the depth of cut Δ L (L-L) of the machined surface 3a₀). The shape calculation unit 75 outputs data including (x, y) coordinates indicating a plurality of points included in the shape data and data indicating the depth of cut Δ L to each of the error calculation unit 76 and the three-dimensional data conversion unit 78 as data (x, y, Δ L) indicating the shape of the machined surface 3 a.

The error calculation unit 76 calculates an error Δ d between the shape calculated by the shape calculation unit 75 and the target shape of the processing surface 3 a. The error calculation unit 76 compares the shape data (x, y, d) output from the coordinate setting unit 73 with the data (x, y, Δ L) indicating the shape output from the shape calculation unit 75, for example, and calculates an error Δ d (d- Δ L) in the z-axis direction at a plurality of points on the processing surface 3 a. The error calculation unit 76 outputs error information indicating the error Δ d in the z-axis direction of the plurality of points to the display 79.

The display processing unit 77 includes a three-dimensional data conversion unit 78 and a display 79.

The three-dimensional data conversion unit 78 converts the data (x, y, Δ L) output from the shape calculation unit 75 into three-dimensional data, and causes the display 79 to three-dimensionally display the processing surface 3a in accordance with the three-dimensional data. The three-dimensional data is data for three-dimensional rendering.

The display 79 is realized by, for example, a liquid crystal display. The display 79 displays the three-dimensional representation of the processing surface 3a and also displays the error Δ d indicated by the error information output from the error calculation unit 76.

Fig. 8 is a hardware configuration diagram showing hardware of a part of the control unit 50. As shown in fig. 8, the coordinate setting unit 73 is realized by a coordinate setting circuit 81, the cutting oil supply unit 74 is realized by a cutting oil supply circuit 82, the shape calculation unit 75 is realized by a shape calculation circuit 83, the error calculation unit 76 is realized by an error calculation circuit 84, and the three-dimensional data conversion unit 78 is realized by a three-dimensional data conversion circuit 85.

It is assumed here that the coordinate setting unit 73, the cutting oil supply unit 74, the shape calculation unit 75, the error calculation unit 76, and the three-dimensional data conversion unit 78, which are part of the components of the control unit 50, are each implemented by dedicated hardware as shown in fig. 8. That is, a case where a part of the control unit 50 is realized by the coordinate setting circuit 81, the cutting oil supply circuit 82, the shape calculation circuit 83, the error calculation circuit 84, and the three-dimensional data conversion circuit 85 is shown. However, the present invention is not limited to this, and a part of the control unit 50 may be implemented by software, firmware, or a combination of software and firmware.

Fig. 9 is a hardware configuration diagram of a computer when a part of the control unit 50 is implemented by software, firmware, or the like. When a part of the control unit 50 is implemented by software, firmware, or the like, a program for causing a computer to execute the processing flow of the coordinate setting unit 73, the cutting oil supply unit 74, the shape calculation unit 75, the error calculation unit 76, and the three-dimensional data conversion unit 78 is stored in the memory 91. Then, the processor 92 of the computer executes the program stored in the memory 91.

Next, the operation of the machine tool according to embodiment 1 will be described. First, the operation of the machine tool in cutting the machining surface 3a of the workpiece 3 will be described. Since the operation of cutting the machined surface 3a is a known operation per se, the operation of cutting the machined surface 3a will be briefly described here.

The input unit 71 receives a supply instruction of cutting oil from a user. When the input section 71 receives the cutting oil supply instruction, the cutting oil supply section 74 outputs a cutting oil supply instruction to the cutting oil nozzle 14, the cutting oil supply instruction indicating that the cutting oil is to be applied to the machining surface 3 a. When receiving a cutting oil supply command from the cutting oil supply unit 74, the cutting oil nozzle 14 applies the cutting oil to the machining surface 3 a.

The input unit 71 receives a machining instruction of the workpiece 3 from a user. When the input unit 71 receives the processing instruction, the coordinate setting unit 73 acquires the shape data stored in the storage device 72.

The coordinate setting unit 73 generates a control signal indicating the movement position of the head main body 11a based on the shape data, and outputs the control signal to the head driving unit 13. Specifically, the coordinate setting unit 73 selects any 1 point from among a plurality of points on the processing surface 3a, generates a control signal of (x, y) coordinates for moving the head main body 11a to the selected 1 point, and outputs the control signal to the head driving unit 13. When the cutting process of the selected 1 point is completed, the coordinate setting unit 73 selects the 1 point at which the cutting process is not completed, generates a control signal of (x, y) coordinates for moving the head main body 11a to the selected 1 point, and outputs the control signal to the head driving unit 13. The coordinate setting unit 73 repeatedly generates the control signal for moving the head main body 11a until the cutting process is completed at all points of the processing surface 3 a.

Each time the control signal is received from the coordinate setting unit 73, the head driving unit 13 moves the head main body 11a to the movement position indicated by the control signal, and then moves the head main body 11a in the z-axis direction based on the depth information d included in the control signal. The machining tool 12 held by the head body 11a performs cutting of the machining surface 3a by, for example, the rotating operation of the spindle 11 b.

When the input section 71 receives a machining instruction from the user for the workpiece 3, the cutting oil supply section 74 outputs a cutting oil supply instruction to the cutting oil nozzle 14. However, this is merely an example, and the cutting oil supply unit 74 may output a supply command of the cutting oil to the cutting oil nozzle 14 at regular time intervals, for example. Further, the following may be provided: the cutting oil supply unit 74 outputs a supply command of the cutting oil to the cutting oil nozzle 14 when the sensor detects the absence of the cutting oil on the machining surface 3 a.

In this case, when the input unit 71 receives a machining instruction from the user for the workpiece 3, the coordinate setting unit 73 outputs a control signal to the head driving unit 13. However, this is only an example, and for example, it may be: when receiving an instruction to machine the workpiece 3 from the outside, the coordinate setting unit 73 outputs a control signal to the head driving unit 13. The coordinate setting unit 73 may output a control signal to the head driving unit 13 according to a program stored in an internal memory.

Next, the operation of the machine tool when measuring the shape of the machining surface 3a of the workpiece 3 will be described. Fig. 10 is a flowchart showing a flow of the machine tool when measuring the shape of the machining surface 3a of the workpiece 3.

The input unit 71 receives a shape measurement instruction of the workpiece 3 from a user. When the input unit 71 receives the shape measurement instruction, the coordinate setting unit 73 acquires the shape data stored in the storage device 72. The coordinate setting unit 73 generates a control signal indicating the movement position of the head main body 11a based on the shape data, and outputs the control signal to each of the head driving unit 13 and the sensor main body 22 (step ST 1). Specifically, the coordinate setting unit 73 selects any 1 point from among a plurality of points on the processing surface 3a, generates a control signal of (x, y) coordinates for moving the head main body 11a to the selected 1 point, and outputs the control signal to the head driving unit 13. The coordinate setting unit 73 outputs a synchronization signal to the sensor main body 22 (step ST 1).

When the measurement of the distance of the selected 1 point is completed, the coordinate setting unit 73 selects the 1 point whose measurement is not completed, generates a control signal of (x, y) coordinates for moving the head main body 11a to the selected 1 point, and outputs the control signal to each of the head driving unit 13 and the sensor main body 22. The coordinate setting unit 73 repeats the generation of the control signal for moving the head main body 11a until the distances of all the points on the processing surface 3a are measured.

The control signal generated by the coordinate setting unit 73 includes information for moving the position of the head main body 11a in the z-axis direction to the reference position. Upon receiving the control signal from the coordinate setting unit 73, the head driving unit 13 moves the head main body 11a to the movement position indicated by the control signal, and thereafter moves the position of the head main body 11a in the z-axis direction to the reference position (step ST 2).

When the synchronization signal is received from the coordinate setting unit 73 and the notification of the completion of the movement is received from the head driving unit 13, the sensor main body 22 starts the distance measurement process and calculates the distance L from the front end 21a of the sensor head 21 to the processing surface 3a (step ST 3).

The following describes the distance calculation process in the sensor main body 22 with reference to fig. 11. Fig. 11 is a flowchart showing a process of calculating the distance in the sensor main body portion 22.

Upon receiving the synchronization signal from the coordinate setting unit 73 and then receiving the notification of the completion of the movement from the head driving unit 13, the sweep light output unit 31 outputs the sweep light whose frequency changes with the passage of time to the optical coupler 33 (step ST 31).

The sweep light is divided into reference light and irradiation light by the optical coupler 33, the irradiation light is output to the circulator 34, and the reference light is output to the optical interferometer 37. The irradiation light enters the condensing optical element 35 through the circulator 34 and the light transmission unit 23, and is condensed on the processing surface 3a by the condensing optical element 35.

The reflected light enters the optical interferometer 37 via the condensing optical element 35, the optical transmission unit 23, and the circulator 34. The reflected light output from the circulator 34 and the reference light output from the optical coupler 33 interfere with each other at the optical interferometer 37, and the interference light is output to the photodetector 38.

The photodetector 38 detects the interference light output from the optical interferometer 37 (step ST 32). The photodetector 38 converts the interference light into an electric signal, and outputs the electric signal to the a/D converter 39.

Upon receiving the electric signal from the photodetector 38, the a/D converter 39 converts the electric signal from an analog signal to a digital signal (step ST33), and outputs the digital signal to the distance calculating unit 40.

Upon receiving the digital signal from the a/D converter 39, the distance calculating unit 40 converts the digital signal into a signal in the frequency domain as shown in fig. 12, for example, by using FFT (Fast Fourier Transform) for the digital signal. Fig. 12 is an explanatory diagram showing an example of a signal in the frequency domain.

The distance calculation unit 40 compares the amplitude of the frequency domain signal with the threshold Th, and detects a frequency having an amplitude larger than the threshold Th as a peak frequency in the frequency domain signal. As described above, since the interference light detected by the photodetector 38 includes the machining surface interference light and the cutting oil interference light, the peak frequency f corresponding to the machining surface interference light is detected₁And with cutting oilPeak frequency f corresponding to interference light₂. The threshold Th is stored in the internal memory of the distance calculation unit 40. The threshold Th may be supplied to the distance calculating unit 40 from the outside.

Here, the distance from the tip 21a of the sensor head 21 to the cutting oil is shorter than the distance from the tip 21a of the sensor head 21 to the machined surface 3a, and therefore the peak frequency f₂Less than peak frequency f₁。f₁＞f₂。

When the peak frequency f is detected₁And peak frequency f₂When the peak frequency f is detected, the distance calculating unit 40 recognizes that the peak frequency f is zero₁And peak frequency f₂The larger peak frequency in the middle is the frequency of the machining surface interference light, and the smaller peak frequency is the frequency of the cutting oil interference light.

The distance calculating unit 40 calculates the peak frequency f based on the frequency of the interference light on the machining surface₁And frequency f of interference light of cutting oil₂The distance L (═ L) from the tip 21a of the sensor head 21 to the processing surface 3a is calculated_oil+L_Depth) (step ST 34).

Using peak frequency f₂Calculating the distance L from the sensor head 21 to the cutting oil_oilThe treatment (2) is represented by the formula (1). In the equation (1), c represents the speed of light, Δ τ represents the scanning time of the swept-frequency light source 31a, Δ v represents the scanning wavelength band, and L represents the known distance from the sensor head 21₀The frequency of the time is set as a reference frequency f₀。

Further, the thickness L of the cutting oil was calculated_DepthAccording to the peak frequency f₁With peak frequency f₂The difference (c), the refractive index n of the cutting oil, the light velocity c, the scanning time Δ τ and the scanning wavelength band Δ v of the swept-frequency light source 31a are expressed by formula (2).

The distance calculating unit 40 outputs distance information indicating the distance L to the shape calculating unit 75 of the control unit 50 (step ST 35).

Returning to fig. 10, as shown in the following expression (3), the shape calculation unit 75 calculates the initial distance L output from the coordinate setting unit 73₀The difference from the distance L indicated by the distance information output from the distance calculating unit 40 is defined as the depth of cut Δ L (see fig. 7B) of the machined surface 3a (step ST 4).

ΔL＝L－L₀ (3)

The shape calculating unit 75 extracts data indicating (x, y) coordinates of a plurality of points on the processing surface 3a from the shape data (x, y, d) indicating the target shape output from the coordinate setting unit 73.

The shape calculation unit 75 outputs data including the extracted (x, y) coordinates representing the plurality of points and the extracted data of the cutting depth Δ L to each of the error calculation unit 76 and the three-dimensional data conversion unit 78 as data (x, y, Δ L) representing the shape of the machined surface 3 a.

The error calculation unit 76 acquires shape data (x, y, d) indicating the target shape output from the coordinate setting unit 73 and shape data (x, y, Δ L) indicating the shape output from the shape calculation unit 75. The error calculation unit 76 compares the shape data (x, y, d) indicating the target shape with the data (x, y, Δ L) and calculates an error Δ d in the z-axis direction at a plurality of points on the processing surface 3a as shown in the following equation (4) (step ST 5). The error Δ d is an error between the cutting depth of the target-shaped machined surface 3a and the cutting depth of the machined surface 3 a.

Δd＝d－ΔL (4)

The error calculation unit 76 outputs error information indicating the error Δ d in the z-axis direction of the plurality of points to the display 79.

When receiving the data (x, y, Δ L) indicating the shape from the shape calculating unit 75, the three-dimensional data converting unit 78 accumulates the data (x, y, Δ L). The three-dimensional data conversion unit 78 accumulates data (x, y, Δ L) at all points on the machining surface 3 a.

The three-dimensional data conversion unit 78 converts the data (x, y, Δ L) at all points on the processing surface 3a into three-dimensional data, and causes the display 79 to display the processing surface 3a three-dimensionally in accordance with the three-dimensional data. The three-dimensional data is data for three-dimensional rendering.

The display 79 displays the three-dimensional representation of the processing surface 3a and also displays the error Δ d indicated by the error information output from the error calculation unit 76 (step ST 6). The error Δ d is displayed on the display 79, so that the user can confirm whether or not the machining of the workpiece 3 by the machine tool is properly performed, for example.

Here, when the input unit 71 receives a shape measurement instruction of the workpiece 3 from the user, the coordinate setting unit 73 outputs a control signal to each unit of the head driving unit 13 and the sensor main body 22. However, this is merely an example, and the coordinate setting unit 73 may output a control signal to each unit of the head driving unit 13 and the sensor main body unit 22 when a shape measurement instruction of the workpiece 3 is received from the outside, for example. The coordinate setting unit 73 may output control signals to the head driving unit 13 and the sensor main body 22 according to a program stored in an internal memory.

In embodiment 1 described above, the machine tool includes the machining unit 10 that supplies the cutting oil to the machining surface 3a of the workpiece 3 to machine the machining surface 3a, and the machine tool includes: an optical sensor unit 20 that separates light output from a sweep light source 31a into irradiation light to be irradiated to the workpiece 3 and reference light, irradiates the irradiation light to the workpiece 3, detects a peak frequency of interference light, which is reflection light of the irradiation light reflected by the workpiece 3 and the reference light, and measures a distance from the machine tool to the processing surface 3a based on the peak frequency, wherein the sweep light source 31a outputs light whose frequency changes periodically; and a shape calculation unit 75 for calculating the shape of the workpiece 3 based on the distance measured by the optical sensor unit 20. Therefore, the machine tool can measure the shape of the workpiece 3 even when the cutting oil remains on the machining surface 3a of the workpiece 3.

Embodiment 2.

In the machine tool according to embodiment 1, the sensor head portion 21 of the optical sensor portion 20 is attached to the head main body portion 11 a. In contrast, in embodiment 2, the machine tool is configured such that the sensor head 21b is attached to the spindle 11 b. Fig. 13 is a configuration diagram showing a machine tool according to embodiment 2. In fig. 13, the same reference numerals as in fig. 1 denote the same or corresponding parts, and thus, the description thereof will be omitted.

In fig. 13, the spindle 11b of the machining head 11 detachably holds the machining tool 12 or the sensor head 21 b. Specifically, when the workpiece 3 is machined, the machining tool 12 is held by the spindle 11b, and when the shape of the workpiece 3 is measured, the sensor head 21b is held by the spindle 11b as shown in fig. 13.

Fig. 14 is a structural diagram showing a sensor head 21b according to embodiment 2. In fig. 14, the sensor head 21b includes a cylindrical case 110. The sensor head 21b includes two aspherical lenses 111 and 112 as the condensing optical element 35, and a mirror 113 for changing the angle of light emitted from the aspherical lens 111 at the front stage toward the aspherical lens 112 at the rear stage. A mounting portion 114 for mounting the optical fiber as the optical transmission portion 23 is provided on a side surface of the housing 110.

Since the mounting portion 114 is provided on the side surface of the housing 110 as described above, even in a state where the sensor head 21b is fixed to the spindle 11b, the irradiation light can be guided to the aspherical lenses 111 and 112 as the condensing optical elements. Further, since the mirror 113 is provided, the irradiation light incident from the side surface can be irradiated to the workpiece 3 in a direction parallel to the central axis of the head main body 11 a.

In embodiment 2 described above, the machine tool is configured such that the sensor head 21b is attached to the spindle 11 b. Therefore, the machine tool can hold the sensor head 21b by using the chuck device provided in the spindle 11 b. Therefore, it is not necessary to provide a separate holding mechanism to attach the sensor head 21b to the machining head 11, and the machine tool can be manufactured at low cost.

Embodiment 3.

In embodiment 3, the machine tool includes a tool storage unit 100, and the tool storage unit 100 stores a plurality of machining tools 12 for machining a machining surface 3 a. The tool storage unit 100 also stores a sensor head 21. Thus, during machining, the spindle 11b detachably holds any 1 of the plurality of machining tools 12 stored in the tool storage unit 100. The spindle 11b holds the sensor head 21b stored in the tool storage unit 100 when measuring the shape.

Fig. 15 is a configuration diagram showing a machine tool according to embodiment 3. In fig. 15, the same reference numerals as those in fig. 13 denote the same or corresponding parts, and thus, the description thereof will be omitted. The tool storage unit 100 is a machine frame that stores a plurality of machining tools 12 and sensor heads 21b for machining the machining surface 3 a.

The tool changer 101 has a mechanism for changing the machining tool 12 held by the spindle 11 b. During machining, the tool changer 101 selects any 1 of the plurality of machining tools 12 stored in the tool storage 100, and holds the selected machining tool 12 on the spindle 11 b. On the other hand, when measuring the shape, the tool changer 101 selects the sensor head 21b stored in the tool storage 100, and holds the selected sensor head 21b on the spindle 11 b. Note that, since the mechanism for replacing the machining tool 12 and the sensor head 21b is a known mechanism per se, detailed description thereof is omitted.

In embodiment 3 described above, the machine tool is configured such that the sensor head 21b is stored in the tool storage unit 100 that stores the machining tool 12. Therefore, the machine tool can be manufactured at low cost without separately providing a storage section for storing the sensor head 21 b.

Further, since the sensor head 21b stored in the tool storage unit 100 is held by the spindle 11b, the sensor head 21b can be operated in the same manner as the machining tool 12. Therefore, it is not necessary to provide a separate holding mechanism to attach the sensor head 21b to the spindle 11b, and the machine tool can be manufactured at low cost.

Embodiment 4.

In embodiment 3, the machine tool is configured such that the spindle 11b holds the sensor head 21b during shape measurement. In contrast, in embodiment 4, the spindle 11b holds the optical sensor unit 20 during shape measurement.

Fig. 16 is a configuration diagram showing a machine tool according to embodiment 4. As shown in fig. 16, the optical sensor section 20 includes a sensor head section 21 and a sensor body section 22. The electrical connection between the optical sensor unit 20 and the machining head 11 will be described with reference to fig. 17. Fig. 17 is a partially enlarged view showing a machine tool according to embodiment 4. As shown in fig. 17, the photosensor section 20 and the spindle 11b have electrical connection sections 121 and 122, respectively. The electrical connection portions 121 and 122 are connection portions defined by an interface Standard of RS-232(Recommended Standard) 232, for example.

The communication cable 25 for transmitting and receiving the distance information, the control signal, the synchronization signal, and other information is connected to the electrical connection portion 122 provided in the main shaft 11 b. The communication cable 25 is led out from the head body 11a through the insides of the spindle 11b and the head body 11a, and is connected to the controller 50. Therefore, the machine tool of embodiment 4 can send and receive signals between the control section 50 and the optical sensor section 20 by connecting the electrical connection section 122 of the spindle 11b and the electrical connection section 121 of the optical sensor section 20.

Returning to fig. 16, the tool storage unit 102 is a rack that stores a plurality of machining tools 12 and the optical sensor unit 20 for machining the machining surface 3 a. The tool changer 101 has a mechanism for changing the machining tool 12 held by the spindle 11 b. During machining, the tool changer 101 selects any 1 of the plurality of machining tools 12 stored in the tool storage 102, and holds the selected machining tool 12 on the spindle 11 b. On the other hand, when measuring the shape, the tool changer 101 selects the optical sensor unit 20 stored in the tool storage 102, and holds the selected optical sensor unit 20 on the spindle 11 b.

In fig. 16 and 17, the same reference numerals as in fig. 15 denote the same or corresponding parts.

In embodiment 4 described above, the machine tool is configured such that the optical sensor unit 20 is stored in the tool storage unit 102 that stores the machining tool 12. Therefore, the machine tool can be manufactured at low cost without separately providing a storage unit for storing the optical sensor unit 20.

Further, since the optical sensor unit 20 stored in the tool storage unit 102 is held by the spindle 11b, the optical sensor unit 20 can be operated in the same manner as the machining tool 12. Therefore, it is not necessary to provide a separate holding mechanism to attach the photosensor section 20 to the spindle 11b, and the machine tool can be manufactured at low cost.

Further, since the communication cable 25 between the control unit 50 and the optical sensor unit 20 is configured to pass through the head main body 11a, it is possible to prevent the communication cable 25 from being disconnected when the machining head 11 is moved.

In the machine tools according to embodiments 1 to 4, the machining unit 19 supplies the cutting oil to the machining surface 3a of the workpiece 3.

However, the oil supplied to the machining surface 3a by the machining portion 19 is not limited to the cutting oil as long as it is a liquid used for the main purpose of preventing wear of the tool accompanying metal machining or preventing an increase in temperature of the tool accompanying metal machining. The liquid used for these main purposes is called a machining oil, and the cutting oil is included in the machining oil. The processing oil also includes discharge oil and the like to be described later.

Embodiment 5.

In embodiments 1 to 4, a machine tool having the photosensor section 20 is described.

In embodiment 5, an electric discharge machine having the photosensor section 20 will be described.

Fig. 18 is a configuration diagram illustrating an electric discharge machining apparatus according to embodiment 5. In fig. 18, the same reference numerals as in fig. 1 denote the same or corresponding parts, and thus, the description thereof will be omitted.

The electric discharge machining apparatus shown in fig. 18 measures the distance from the electric discharge machining apparatus to the machining surface 3a using the electrode 15 attached to the machining head 11, and calculates the shape of the workpiece 3 based on the measured distance.

The vise 2' is a fixture for fixing the workpiece 3 without moving it when the workpiece 3 is machined.

The processing tank 4 is a container for storing electric discharge oil 5 as processing oil. The table 1 and the workpiece 3 are each accommodated in the machining tank 4 so that the entire surface thereof is immersed in the discharge oil 5.

The electrode 15 is attached to an outer peripheral surface 11c facing the table 1 among a plurality of outer peripheral surfaces of the head main body portion 11 a. The electrode 15 has a front end portion 15a that emits electrons. By applying a voltage between the distal end portion 15a and the machining surface 3a of the workpiece 3, the electrode 15 causes a spark due to the electric discharge to be generated. Since the machined surface 3a is shaved by the spark generation, the workpiece 3 can be machined. As the electrode 15, a material having high conductivity such as copper or graphite is used.

In the electric discharge machine shown in fig. 18, as in the machine tool shown in fig. 1, the optical sensor section 20 calculates the distance from the tip 21a of the sensor head 21 to the machining surface 3a of the workpiece 3, and calculates the shape of the workpiece 3 based on the calculated distance.

When the optical sensor unit 20 calculates the distance, the sensor head 21 irradiates the irradiation light output from the sensor body 22 toward the processing surface 3a, as in embodiment 1. The sensor head 21 receives reflected light including reflected light as the irradiation light reflected by the machined surface 3a and reflected light as the irradiation light reflected by the discharge oil 5. The sensor head portion 21 outputs the received reflected light to the sensor main body portion 22.

When the machining portion 10 machines the machining surface 3a, the entire workpiece 3 needs to be immersed in the electric discharge oil 5. On the other hand, when the optical sensor unit 20 calculates the distance, the machining surface 3a of the workpiece 3 may be immersed in the discharge oil 5 or may not be immersed in the discharge oil 5. Therefore, the optical sensor unit 20 may calculate the distance in a state where the machining surface 3a of the workpiece 3 is not immersed in the discharge oil 5 by moving the table 1 in the-z-axis direction using an actuator or the like, not shown.

In embodiment 5 described above, the electric discharge machining apparatus includes the machining portion 10 that machines the machining surface 3a of the workpiece 3 immersed in the machining oil, and is configured to include: an optical sensor unit 20 that separates light output from a sweep light source 31a, which outputs light whose frequency varies periodically in 1 frequency band, into irradiation light and reference light that irradiate a workpiece 3, irradiates the workpiece 3 with the irradiation light, detects a peak frequency of interference light, which is interference light between reflected light of the irradiation light reflected by the workpiece 3 and the reference light, and measures a distance from the electric discharge machining apparatus to a machining surface 3a based on the peak frequency; and a shape calculation unit 75 for calculating the shape of the workpiece 3 based on the distance measured by the optical sensor unit 20. Therefore, the electric discharge machining apparatus can measure the shape of the workpiece 3 even when the machining oil remains on the machining surface 3a of the workpiece 3.

In the present invention, any of the components of the embodiments may be freely combined, modified, or omitted within the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a machine tool and an electric discharge machining apparatus for machining a machining surface of a workpiece.