MACHINE TOOL

Abstract

A frequency-swapped light emission unit (421) for emitting frequency-swapped light; a light splitting unit (422) for splitting the frequency-swapped light emitted by the frequency-swapped light emission unit (421) into reference light and irradiation light; a sensor head unit (41) for causing a machining surface (101) of a workpiece (10) to be irradiated with the irradiation light obtained by the light splitting unit (422) after machining, and for receiving reflected light from the machining surface (101); a light interference unit (423) for generating interference light of the reference light obtained by the light splitting unit (422) and the reflected light received by the sensor head unit (41) based on the reference light and the reflected light, and for converting the interference light into an electrical signal;The following are included: an analog-to-digital converter (424) to convert the electrical signal obtained from the light interference unit (423), which is an analog signal, into a digital signal; a distance information calculation unit (425) to calculate information about the distance from the front end of the sensor head unit (41) to the machining surface (101) of the workpiece (10) after machining, based on the digital signal obtained from the analog-to-digital converter (424); and a roughness determination unit (426) to determine the surface roughness of the machining surface (101) of the workpiece (10) after machining, based on a result of the calculation by the distance information calculation unit (425).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a machine tool for determining or measuring the surface roughness of a machining surface of a workpiece. BACKGROUND TO THE STATE OF THE ART

[0002] A conventional machine tool is known that can machine a target object and determine the surface condition of the target object's machining surface after machining (see, for example, Patent Literature 1). The machine tool disclosed in Patent Literature 1 determines the surface condition on the machine tool's surface using a touch probe. REFERENCE LISTPATENT LITERATURE

[0003] Patent Literature 1: JP 2018-36083 A SUMMARY OF THE INVENTIONTECHNICAL PROBLEM

[0004] Here, the contact-type probe scheme disclosed in Patent Literature 1 enables highly accurate on-machine measurement. However, according to this probe scheme, a workpiece surface is damaged, and the size of the R-chamfer at the front end of the probe is limited.

[0005] The present disclosure has been made to solve the problems explained above, and an object thereof is to provide a machine tool which makes it possible to determine the surface roughness of a workpiece in a non-contact manner at the machine of the machine tool. SOLUTION TO THE PROBLEM

[0006] A machine tool according to the present disclosure includes: a machining unit for performing machining on a machining surface of a workpiece; a light sensor unit for detecting a surface roughness of the machining surface of the workpiece after machining by the machining unit, the light sensor unit including: a frequency-swept light emitting unit for emitting frequency-swept light; a light splitting unit for splitting the frequency-swept light emitted by the frequency-swept light emitting unit into reference light and irradiation light; a sensor head unit for irradiating the machining surface of the workpiece after machining by the machining unit with the irradiation light obtained by the light splitting unit and receiving reflection light from the machining surface;a light interference unit for generating interference light of the reference light obtained by the light splitting unit and the reflection light received by the sensor head unit based on the reference light and the reflection light, and converting the interference light into an electrical signal; an analog-to-digital converter for converting the electrical signal obtained by the light interference unit, which is an analog signal, into a digital signal; a distance information calculation unit for calculating information about a distance from a front end of the sensor head unit to the processing surface of the workpiece after processing by the processing unit based on the digital signal obtained by the analog-to-digital converter;a roughness determination unit for determining the surface roughness of the machining surface of the workpiece after machining by the machining unit based on a result of calculation by the distance information calculation unit; ADVANTAGEOUS EFFECTS OF THE INVENTION

[0007] Since the present disclosure is conceived in the manner described above, it is possible to determine the surface roughness of a workpiece on the machine of a machine tool in a non-contact manner. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a figure illustrating a configuration example of a machine tool according to a first embodiment. Fig. 2 is a figure illustrating a configuration example of a light sensor unit in the first embodiment. Fig. 3 is a figure showing an example of frequency swept light used at the light sensor unit according to the first embodiment. Fig. 4 is a figure showing an example of reflected light of irradiation light irradiated to a workpiece in the machine tool according to the first embodiment. Fig. 5 is a figure illustrating a hardware configuration example of a control unit in the first embodiment. Fig. 6 is a figure illustrating an example of a reception spectrum used at a roughness determination unit in the first embodiment. Fig. 7 is a flowchart showing an example of work performed by the sensor body unit in the first embodiment. Fig. 8 is a figure illustrating a configuration example of a light sensor unit in a second embodiment. DESCRIPTION OF THE EMBODIMENTS

[0008] The embodiments will be described in detail below with reference to the drawings. First embodiment.

[0009] Fig. 1 is a figure illustrating a configuration example of a machine tool according to a first embodiment.

[0010] The machine tool is a tool for performing machining on a machining surface 101 of a workpiece 10 and for determining the surface roughness of the machining surface 101 of the workpiece 10 after machining. Note that examples of the workpiece 10 include, for example, a metal or the like. Furthermore, for the convenience of explanation, in the first embodiment, it is assumed that the shape of the machining surface 101 is flat before machining by the machine tool.

[0011] As in Fig. 1, the machine tool comprises a table 1, a vice 2, a machining unit 3, a light sensor unit 4 and a control unit 5.

[0012] The table 1 is a table with a surface on which the workpiece 10, which is a machining target, is to be placed.

[0013] The vice 2 is a fixing element that is attached to the workpiece 10 placed on the table 1 and serves to fix the workpiece 10 in such a way that the workpiece 10 does not move.

[0014] The machining unit 3 is a section for supplying the workpiece 10 placed on the table 1 and fixed by the vice 2 with cutting oil and performs the machining on the machining surface 101.

[0015] As in Fig. 1, the machining unit 3 comprises a machining head 31, a machining tool 32, a head drive unit 33 and a cutting oil nozzle 34 (not shown).

[0016] As in Fig. 1, the machining head 31 comprises a head body unit 311 and a spindle (tool holding unit) 312.

[0017] The head body unit 311 is a metallic structure to support the spindle 312.

[0018] The spindle 312 is a portion for holding the machining tool 32. The spindle 312 is a metallic shaft-shaped part that has a built-in clamp (not shown) for removably holding the machining tool 32 and can drive the machining tool 32 held thereby to rotate.

[0019] It should be noted that a part (a sensor head part 41 explained later) of the light sensor unit 4 is attached to the head body unit 311.

[0020] The machining tool 32 is a cutting tool that is held by the spindle 312 and cuts / machines the machining surface 101 of the workpiece 10 by rotating with the spindle 312. Examples of the machining tool 32 include cutters for metalworking, such as a milling cutter, an end mill, a drill, or a tap.

[0021] The head drive unit 33 is a drive mechanism for relatively changing the position of the head body unit 311 with respect to the machining surface 101 in accordance with a control signal output from a control unit 5.

[0022] The direction in which the position of the head body unit 311 is changed by the head drive unit 33 is the x-axis direction, the y-axis direction, or the z-axis direction, as shown in Fig. 1 is shown.

[0023] It should be noted that after the head body unit 311 moves in accordance with a control signal from the control unit 5, the head drive unit 33 notifies a sensor body unit 42 that the movement has been completed.

[0024] The cutting oil nozzle 34 is a nozzle for applying the cutting oil to the machining surface 101 of the workpiece 10 according to a cutting oil supply command from the control unit 5.

[0025] The light sensor unit 4 is a section for detecting the surface roughness of the processing surface 101 of the workpiece 10 in a non-contact manner after processing by the processing unit 3. At this time, the light sensor unit 4 measures the surface roughness of the processing surface 101 by calculating the distance from a front end 41a of the sensor head unit 41 to the processing surface 101 of the workpiece 10 after processing by the processing unit 3.

[0026] As in Fig. 1, the light sensor unit 4 comprises the sensor head unit 41, the sensor body unit 42 and a light transmission unit 43.

[0027] The sensor head unit 41 is attached to an outer peripheral surface 311a, which is one of the outer peripheral surfaces of the head body unit 311 and which faces a surface of the table 1 on which the workpiece 10 is to be placed.

[0028] A sensor head unit 41 irradiates the processing surface 101 to be irradiated with the irradiation light emitted from the sensor body unit 42 and receives reflected light from the processing surface 101. The reflected light received by the sensor head unit 41 is emitted to the sensor body unit 42.

[0029] A configuration example of the sensor head unit 41 will be mentioned later.

[0030] The sensor body unit 42 outputs the irradiation light to the sensor head unit 41 based on a control signal from the control unit 5. Note that the sensor body unit 42 receives a control signal from the control unit 5 (a signal representing a movement position of the head body unit 311), receives notification from the head drive unit 33 that movement of the head body unit 311 has been completed according to the control signal, and then starts outputting the irradiation light to the sensor head unit 41. The sensor body unit 42 receives the reflected light output from the sensor head unit 41.Then, the sensor body unit 42 measures the surface roughness of the machining surface 101 by calculating the distance from the front end 41a of the sensor head unit 41 to the machining surface 101 of the workpiece 10 after machining by the machining unit 3 based on the above-described irradiation light and the above-described reflected light. A signal representing a result of the detection by the sensor body unit 42 is output to the control unit 5.

[0031] A configuration example of the sensor body unit 42 will be mentioned later.

[0032] The light transmission unit 43 is a transmission path for light directed from the sensor body unit 42 to the sensor head unit 41 and for light directed from the sensor head unit 41 to the sensor body unit 42. The light transmission unit 43 is configured using an optical fiber.

[0033] It should be noted that the machine tool is designed according to the Fig. 1 is equipped with the light transmission unit 43. However, this is not the only example; the light transmission unit 43 is not an essential part of the machine tool, and the machine tool may not be equipped with the light transmission unit 43. In a case where the machine tool is not equipped with the light transmission unit 43, the light directed from the sensor body unit 42 to the sensor head unit 41 and the light directed from the sensor head unit 41 to the sensor body unit 42 are transmitted across a space.

[0034] The control unit 5 is a section for controlling the work performed by the machine tool.

[0035] The control unit 5 outputs a control signal representing a movement position of the head body unit 311 to the head drive unit 33 and the sensor body unit 42. Furthermore, the control unit 5 outputs the command to supply cutting oil to the cutting oil nozzle 34.

[0036] In addition, the control unit 5 calculates the shape of the machining surface 101 based on the relative position of the head body unit 311 with respect to the machining surface 101 based on the above-described control signal and the result of detection by the sensor body unit 42.

[0037] Next, configuration examples of the sensor head unit 41 and the sensor body unit 42 will be described with reference to Fig. 2 explained.

[0038] As in Fig. 2, the sensor head unit 41 has the condensing optical element 411.

[0039] Furthermore, as in Fig. 2, the sensor body unit 42 includes a frequency swept light emitting unit 421, a light splitting unit 422, a light interference unit 423, an analog-to-digital converter (hereinafter referred to as A / D converter) 424, a distance information calculating unit 425, and a roughness determining unit 426.

[0040] The frequency-swept light output unit 421 outputs frequency-swept light to the light splitting unit 422. The frequency-swept light is light whose frequency changes over time.

[0041] Note that the frequency swept light emitting unit 421 receives a control signal from the control unit 5 (a signal representing the moving position of the head body unit 311), receives a notification from the head driving unit 33 that the movement of the head body unit 311 has been completed according to the control signal, and then starts emitting the frequency swept light.

[0042] Fig. 3 is an explanatory diagram showing an example of the frequency-swept light emitted from the frequency-swept light emitting unit 421. In Fig. 3, a solid line waveform denoted by reference numeral 301 represents the frequency-swept light, and a dashed line waveform denoted by reference numeral 302 represents light generated from the frequency-swept light (irradiation light) by reflecting it on the processing surface 101. Furthermore, the frequency difference between the solid line waveform and the dashed line waveform denoted by reference numeral 303 represents interference light.

[0043] As in Fig. 3, the frequency swept light emitted by the frequency swept light emitting unit 421 is a signal having a frequency that changes over time from the lowest frequency f min to the highest frequency f max changes. When the frequency of the frequency-swept light reaches the highest frequency f max reached, the frequency temporarily returns to the lowest frequency f min back and then changes again from the lowest frequency f min into the highest frequency f max . It should be noted that in some cases, the frequency-swept light may also be referred to as chirped signal light.

[0044] The light splitting unit 422 splits the frequency-swept light outputted by the frequency-swept light outputting unit 421 into reference light and irradiation light. As shown in Fig. 2, the light splitting unit 422 includes a light coupler 4221 and a circulator 4222.

[0045] The light coupler 4221 is a light splitting element that splits the frequency-swept light output by the frequency-swept light output unit 421 into the reference light and the irradiation light. The reference light obtained by the light coupler 4221 is output to the light interference unit 423 (a light interferometer 4231 mentioned later), and the irradiation light obtained by the light coupler 4221 is output to the circulator 4222.

[0046] The circulator 4222 outputs the irradiation light obtained with the light coupler 4221 to the sensor head unit 41 (condensing optical element 411) via the light transmission unit 43.

[0047] Furthermore, the circulator 4222 outputs the reflected light (condensing optical element 411) emitted from the sensor head unit 41 to the light interference unit 423 (light interferometer 4231).

[0048] The condensing optical element 411 condenses the irradiation light emitted from the sensor body unit 42 (circulator 4222) onto the processing surface 101 of the workpiece 10.

[0049] Specifically, the condensing optical element 411 includes two aspherical lenses. The condensing optical element 411 collimates the irradiation light emitted from the sensor body unit 42 (circulator 4222) with the upstream aspherical lens, then condenses the collimated light with the downstream aspherical lens, and irradiates the processing surface 101 of the workpiece 10 with the condensed light.

[0050] Fig. 4 is an explanatory diagram showing an example of the reflected light generated from the reference light with which the condensing optical element 411 irradiates the processing surface 101.

[0051] The irradiation light emitted by the condensing optical element 411 forms a light spot or beam spot with a certain area, as shown in Fig. 4. Then, the irradiation light is reflected from each of the concavities and convexities on the processing surface 101 in the beam spot region.

[0052] Then, the condensing optical element 411 receives the reflected light from the processing surface 101. The reflected light received by the condensing optical element 411 is output to the light interference unit 423 (light interferometer 4231) via the light transmission unit 43 and the circulator 4222.

[0053] It should be noted that in Fig. 4 the reference numerals 401a to 401n denote the irradiation light, the reference numerals 402a to 402n denote the reflection light and the reference numeral 403 denotes the beam spot.

[0054] The light interference unit 423 generates the interference light of the reference light emitted by the light splitting unit 422 and the reflection light (the reflection light received by the sensor head unit 41) based on the reference light and the reflection light. The light interference unit 423 then converts the generated interference light into an electrical signal. As shown in Fig. 2, the light interference unit 423 comprises the light interferometer 4231 and a light detector 4232.

[0055] The light interferometer 4231 receives the input of the reference light obtained by the light coupler 4221 and the reflected light emitted by the circulator 4222, and generates the interference light of the reference light and the reflected light. The interference light generated by the light interferometer 4231 is output to the light detector 4232.

[0056] The light detector 4232 detects the interference light generated by the light interferometer 4231 and converts the interference light into an electrical signal. The electrical signal obtained by the light detector 4232 is output to the A / D converter 424.

[0057] The A / D converter 424 converts the electrical signal obtained by the light detector 4232 into a digital signal. The digital signal obtained by the A / D converter 424 is output to the distance information calculation unit 425.

[0058] The distance information calculation unit 425 calculates information about the distance from the front end 41a of the sensor head unit 41 to the processing surface 101 of the workpiece 10 after processing by the processing unit 3 based on the digital signal obtained from the A / D converter 424. At this time, the distance information calculation unit 425 analyzes the frequency of the interference light generated by the light interference unit 423 by converting the digital signal obtained from the A / D converter 424 into a frequency domain signal, and obtains a reception spectrum, which is frequency information about the interference light of the processing surface, as the distance information described above.That is, the light sensor unit 4 can acquire information of different frequencies due to distance differences caused by the concavities and convexities on the processing surface 101 in the beam spot of the irradiation light irradiating the processing surface 101. With this in mind, the distance information calculation unit 425 calculates the reception spectrum as the distance information. A signal representing the distance information (reception spectrum) calculated by the distance information calculation unit 425 is output to the roughness determination unit 426.

[0059] Note that the distance information calculation unit 425 is implemented, for example, by a distance information calculation circuit, which is not shown. The distance information calculation circuit is, for example, a single circuit, a compound circuit, a programmable processor, a parallel programmable processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (PFGA), or a combination of these circuits.

[0060] Furthermore, although the distance information calculation unit 425 is illustrated here as being implemented by the distance information calculation circuit, which is dedicated hardware, this is not the only example, and the distance information calculation unit 425 may be implemented by software, firmware, or a combination of software and firmware. The software or firmware is stored in a computer memory as a program. The computer represents hardware for executing the program and is equivalent to, for example, a central processing unit (CPU), a central processor, a processing unit, a computing device, a microprocessor, a microcomputer, a processor, or a digital signal processor (DSP). Fig. 5 is a hardware configuration diagram of the computer in a case where the distance information calculation unit 425 is implemented by software, firmware, or the like. In a case where the distance information calculation unit 425 is implemented by software, firmware, or the like, a program that causes the computer to execute a processing operation performed in the distance information calculation unit 425 is stored in a memory 201. Then, a processor 202 of the computer executes the program stored in the memory 201.

[0061] The roughness determination unit 426 determines the surface roughness of the processing surface 101 of the workpiece 10 after processing by the processing unit 3 based on a calculation result by the distance information calculation unit 425. At this time, the roughness determination unit 426 determines the surface roughness of the processing surface 101 of the workpiece 10 after processing by the processing unit 3 by determining the surface roughness of the processing surface 101 in the beam spot based on the broadening (spectral width) of the reception spectrum obtained by the distance information calculation unit 425. A signal representing a determination result by the roughness determination unit 426 is output to the control unit 5.

[0062] Fig. 6 is an explanatory diagram showing an example of the reception spectrum used in the roughness detecting unit 426.

[0063] Since the reflected light at different frequencies is observed in the beam spot due to the concavities and convexities on the processing surface 101, the received spectrum exhibits a broadening depending on the roughness of the concavities and convexities. From the broadening of the received spectrum, the roughness determination unit 426 can therefore determine the surface roughness of the processing surface 101.

[0064] It should be noted that in Fig. 6, a waveform represented by a solid line represents a case of RZ 3.2, and a waveform represented by a dashed line represents a case of RZ 10. RZ is an index indicating the maximum roughness. RZ 3.2 means that the maximum value of the surface roughness is 3.2 μm, and RZ 10 means that the maximum value of the surface roughness is 10 μm. Fig. 6 it can be seen that the width of the reception spectrum increases with increasing surface roughness of the machining surface 101.

[0065] It should be noted that the lower portion of the reception spectrum obtained by the distance information calculation unit 425 has low signal intensity and is not suitable for signal analysis. Therefore, the distance information calculation unit 425 may calculate the reception spectra multiple times, and the roughness determination unit 426 may integrate the intensities of the reception spectra and determine the surface roughness of the processing surface 101 of the workpiece 10 after processing by the processing unit 3 based on the integration result. This makes it easier for the roughness determination unit 426 to analyze the lower portions of the reception spectra.

[0066] Next, an example of work performed by the sensor body unit 42 in the Fig. 2 illustrated first embodiment, with reference to Fig. 7 explained.

[0067] In the example of the work performed by the sensor body unit 42 in the Fig. 2 shown first embodiment is carried out as in Fig. As shown in Figure 7, first, the frequency-swept light output unit 421 outputs the frequency-swept light with a frequency that changes over time to the light coupler 4221 (step ST701). Note that the frequency-swept light output unit 421 receives a control signal from the control unit 5 (the signal representing the movement position of the head body unit 311), receives notification from the head drive unit 33 that the movement of the head body unit 311 has been completed according to the control signal, and then starts outputting the frequency-swept light.

[0068] The frequency-swept light is split into reference light and irradiation light by the light coupler 4221. The irradiation light is then delivered to the circulator 4222, and the reference light is delivered to the light interferometer 4231.

[0069] Then, the irradiation light is delivered to the condensing optical element 411 via the circulator 4222 and the light transmission unit 43, and the condensing optical element 411 irradiates the processing surface 101 with the irradiation light. The irradiation light is then reflected on the processing surface 101, and the reflected light is received by the condensing optical element 411.

[0070] Thereafter, the reflected light is transmitted to the light interferometer 4231 via the condensing optical element 411, the light transmission unit 43 and the circulator 4222.

[0071] Then, the reflected light emitted from the circulator 4222 and the reference light emitted from the light coupler 4221 interfere at the light interferometer 4231, and the interference light therefrom is emitted to the light detector 4232.

[0072] Next, the light detector 4232 detects the interference light generated by the light interferometer 4231 (step ST702). The light detector 4232 then converts the interference light into an electrical signal. The electrical signal obtained by the light detector 4232 is output to the A / D converter 424.

[0073] Next, after receiving the electrical signal from the light detector 4232, the A / D converter 424 converts the electrical signal, which is an analog signal, into a digital signal (step ST703). The digital signal obtained by the A / D converter 424 is output to the distance information calculation unit 425.

[0074] After receiving the digital signal from the A / D converter 424, the distance information calculation unit 425 obtains a reception spectrum as shown in Fig. 6, by converting the digital signal into a frequency-domain signal (step ST704). At this time, for example, the distance information calculation unit 425 converts the above-described digital signal into a frequency-domain signal using Fast Fourier Transform (FFT). A signal representing the reception spectrum obtained by the distance information calculation unit 425 is output to the roughness determination unit 426.

[0075] After receiving the signal representing the reception spectrum from the distance information calculation unit 425, the roughness determination unit 426 determines the surface roughness of the machining surface 101 in the beam spot of the irradiated light by analyzing the broadening of the reception spectrum (step ST705). A signal representing a result of the determination by the roughness determination unit 426 is output to the control unit 5.

[0076] Furthermore, the control unit 5 calculates the shape of the machining surface 101 based on the relative position of the head body unit 311 with respect to the machining surface 101 based on the control signal and a result of detection by the roughness detection unit 426.

[0077] As mentioned above, the machine tool according to the first embodiment includes: the machining unit 3 for performing machining on the machining surface 101 of the workpiece 10; and the light sensor unit 4 for detecting the surface roughness of the machining surface 101 of the workpiece 10 after machining by the machining unit 3. The light sensor unit 4 includes: the frequency-swept light output unit 421 for outputting the frequency-swept light; the light splitting unit 422 for splitting the frequency-swept light output from the frequency-swept light output unit 421 into the reference light and the irradiation light; the sensor head unit 41 for causing the processing surface 101 of the workpiece 10 after processing by the processing unit 3 to be irradiated with the irradiation light obtained from the light splitting unit 422, and for receiving the reflection light from the processing surface 101;The light interference unit 423 generates the interference light of the reference light obtained by the light splitting unit 422 and the reflection light received by the sensor head unit 41 based on the reference light and the reflection light, and converts the interference light into the electrical signal; an A / D converter 424 converts the electrical signal obtained by the light interference unit 423, which is an analog signal, into a digital signal; a distance information calculation unit 425 calculates information about the distance from the front end 41a of the sensor head unit 41 to the processing surface 101 of the workpiece 10 after processing by the processing unit 3 based on the digital signal obtained by the A / D converter 424.and a roughness determination unit 426 for determining the surface roughness of the machining surface 101 of the workpiece 10 after machining by the machining unit 3 based on the result of the calculation by the distance information calculation unit 425. The machine tool according to the first embodiment enables the surface roughness of the workpiece 10 to be determined in a non-contact manner on the machine of the machining unit 3. Second embodiment.

[0078] Fig. Fig. 8 is a figure showing a configuration example of a light sensor unit 4 in a second embodiment. In the light sensor unit 4 of the Fig. In the second embodiment shown in Fig. 8, a polarization rotation unit 427 is added to the light sensor unit 4 of the Fig. 2. Incidentally, the configuration example of the light sensor unit 4 in the second embodiment shown in Fig. 8, the configuration example of the light sensor unit 4 in the first embodiment shown in Fig. 2, identical reference numerals are assigned, and only the differences are explained.

[0079] The polarization rotation unit 427 rotates the polarization of the frequency-swept light output from a frequency-swept light output unit 421. The polarization rotation unit 427 reduces the detection errors dependent on the polarization of the frequency-swept light by scrambling the polarization at a certain constant speed using a polarization scrambler or the like. The frequency-swept light, after the polarization rotation by the polarization rotation unit 427, is output to a light splitting unit 422.

[0080] Note that in the second embodiment, the light splitting unit 422 splits the frequency-swept light into reference light and irradiation light after the polarization rotation by the polarization rotation unit 427. That is, a light coupler 4221 splits the frequency-swept light into reference light and irradiation light after the polarization rotation by the polarization rotation unit 427.

[0081] As mentioned above, the machine tool according to the second embodiment includes the polarization rotation unit 427 for rotating the polarization of the frequency-swept light output from the frequency-swept light output unit 421, and the light splitting unit 422 splits the frequency-swept light into the reference light and the irradiation light after the polarization rotation by the polarization rotation unit 427. Therefore, the machine tool according to the second embodiment enables a reduction in detection errors depending on the polarization of the frequency-swept light compared to the machine tool according to the first embodiment.

[0082] It should be noted that a combination of the embodiments, a modification of any components of the embodiments, or omission of any components in each of the embodiments are possible. INDUSTRIAL APPLICABILITY

[0083] The machine tool according to the present disclosure enables contactless determination of the surface roughness of a workpiece on the machine of the machining unit and is suitable for use for a machine tool or the like for determining the surface roughness of a machining surface of a workpiece. LIST OF REFERENCE SYMBOLS

[0084] 1: Table, 2: Vice, 3: Machining unit, 4: Light sensor unit, 5: Control unit, 10: Workpiece, 31: Machining head, 32: Machining tool, 33: Head drive unit, 34: Cutting oil nozzle, 41: Sensor head unit, 41a: Front end, 42: Sensor body unit, 43: Light transmission unit, 101: Machining surface, 201: Memory, 202: Processor, 311: Head body unit, 311a: Outer peripheral surface, 312: Spindle, 411: Condensing optical element, 421: Frequency swept light emitting unit, 422: Light splitting unit, 423: Light interference unit, 424: A / D converter, 425: Distance information calculating unit, 426: Roughness detection unit, 427: Polarization rotation unit, 4221: Light coupler, 4222: Circulator, 4231: Light interferometer, 4232: Light detector QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2018-36083 A

[0003]

Claims

[1] Machine tool, comprising: a machining unit for performing machining on a machining surface of a workpiece; and a light sensor unit for determining a surface roughness of the machining surface of the workpiece after machining by the machining unit, wherein the light sensor unit has: a frequency swept light emitting unit for emitting frequency swept light; a light splitting unit for splitting the frequency swept light outputted from the frequency swept light outputting unit into reference light and irradiation light; a sensor head unit for causing the processing surface of the workpiece after processing by the processing unit to be irradiated with the irradiation light obtained by the light splitting unit and for receiving reflection light from the processing surface; a light interference unit for generating interference light of the reference light obtained by the light splitting unit and the reflection light received by the sensor head unit based on the reference light and the reflection light, and converting the interference light into an electrical signal; an analog-to-digital converter for converting the electrical signal obtained by the light interference unit, which is an analog signal, into a digital signal; a distance information calculation unit for calculating information about a distance from a front end of the sensor head unit to the machining surface of the workpiece after machining by the machining unit based on the digital signal obtained by the analog-to-digital converter; and a roughness determination unit for determining the surface roughness of the machining surface of the workpiece after machining by the machining unit based on a result of calculation by the distance information calculation unit. [2] Machine tool according to claim 1, wherein the machining unit comprises: a tool holding unit for holding a machining tool to be used for machining on the machining surface of the workpiece; and a head body unit for holding the tool holding unit; and part of the light sensor unit is attached to the head body unit. [3] A machine tool according to claim 2, wherein the sensor head unit is attached to the head body unit. [4] A machine tool according to claim 3, comprising a table having a surface on which the workpiece is to be placed, wherein the sensor head unit is attached to an outer peripheral surface which is one of the outer peripheral surfaces of the head body unit and which faces the surface of the table on which the workpiece is to be placed. [5] The machine tool according to claim 1, comprising a polarization rotation unit for rotating polarization of the frequency swept light output from the frequency swept light output unit, wherein the light splitting unit splits the frequency swept light into the reference light and the irradiation light after the rotation of the polarization by the polarization rotation unit.

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