JP2023147596A - Processing device, processing state monitoring method and cutting tool - Google Patents

Abstract

To provide a technique for monitoring a processing state by utilizing a principle of a tool-material to be cut thermocouple method.SOLUTION: A rotating mechanism 11 rotates a spindle 10 mounted with a cutting tool 20 or with a material 30 to be cut. A movement control part 102 controls relative movement of the cutting tool 20 with respect to the material 30 to be cut. A monitoring part 104 monitors a processing state, while using thermoelectromotive force generated at a plurality of contact points at which the cutting tool 20 contacts the material 30 to be cut, during rotation of the spindle.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a machining device, a machining state monitoring method, and a cutting tool.

The tool-workpiece thermocouple method is known as a method for measuring the temperature of the tool edge during cutting. The tool-workpiece thermocouple method uses the Seebeck effect, which occurs when a temperature difference occurs between the contacts of a loop made of two types of conductors, a thermoelectromotive force is generated between the contacts and current flows through the loop. The tool tip temperature (cutting temperature) is measured from the thermoelectromotive force generated between the tool and the workpiece. Since the thermoelectromotive force is determined by the temperatures of the two contact points and the materials of the two types of conductors, by measuring the thermoelectromotive force, the cutting temperature can be determined from a temperature calibration curve created in advance. Although the main component of the cutting tool material is generally nonmetallic, it often contains a conductive binder and the like, so thermoelectromotive force can be measured.

Non-Patent Document 1 discloses a structure for realizing the tool-workpiece material thermocouple method, which uses a mercury contact as an electrical contact between the rotating spindle and a stationary structure to prevent a short circuit between the tool and the workpiece material. A structure using insulating parts is disclosed. Furthermore, Non-Patent Document 2 discloses a structure for realizing the tool-workpiece material thermocouple method, in which a slip ring is used as an electrical contact point between the rotating spindle and a fixed structure, and an electrical The present invention discloses a structure using standard insulating parts.

Milton C. Shaw, “Metal Cutting Principles”, Claendon Press Oxford, 1984, p.252 Itaru Yamazaki, “Machining characteristics in interrupted cutting of high hardness materials”, Nachi Technical Report - Machining, Fujikoshi Co., Ltd., Oct 2011, Vol.23A2

In both of the techniques disclosed in Non-Patent Documents 1 and 2, an electric contact is provided on the rear end side of the rotating main shaft, so the rotating main shaft needs to be modified, which increases cost. Additionally, the use of mercury poses safety problems, and slip rings are difficult to use on spindles that rotate at high speeds. Therefore, there is a need for the development of a technology to easily monitor the machining status without modifying the rotating spindle or using mercury or slip rings.

The present disclosure has been made in view of these circumstances, and its purpose is to provide a technique for monitoring the state of machining using the principle of the tool-workpiece thermocouple method.

In order to solve the above problems, a processing device according to an aspect of the present disclosure includes a rotation mechanism that rotates a main shaft to which a cutting tool or a workpiece is attached, and a rotation mechanism that controls relative movement of the cutting tool with respect to the workpiece. It includes a movement control section and a monitoring section that monitors the machining state using thermoelectromotive force generated at a plurality of contact points where the cutting tool and the workpiece come into contact while the spindle is rotating.

A machining state monitoring method according to another aspect of the present disclosure includes a step of measuring a difference in thermoelectromotive force generated at a plurality of contact points where a cutting tool and a workpiece come into contact; and monitoring the machining state using the power difference.

A cutting tool according to still another aspect of the present disclosure includes a plurality of conductive contact members that contact a workpiece when processing the workpiece, a fixing member to which the plurality of contact members are fixed, and a plurality of contact members. and an electrically conductive member connected to at least one contact member.

Note that any combination of the above components and the expressions of the present disclosure converted between methods, devices, systems, etc. are also effective as aspects of the present disclosure.

FIG. 1 is a diagram showing a schematic configuration of a processing device according to an embodiment. It is a figure showing an example of a cutting tool. It is a figure which shows the experimental result showing the relationship between cutting temperature and cutting speed. It is a figure which shows the experimental result showing the relationship between cutting temperature and feed amount. It is a figure showing an example of a cutting tool. FIG. 2 is a diagram illustrating an example of a circuit that measures voltages at multiple contact points. It is a figure showing an example of a cutting tool. It is a figure showing an example of a cutting tool.

FIG. 1 shows an example of a schematic configuration of a processing apparatus 1 according to an embodiment. The processing device 1 of the embodiment is a lathe that rotates a workpiece 30 attached to a main shaft 10 via a chuck 31 and causes a cutting edge of a cutting tool 20 to cut into the rotating workpiece 30. The cutting tool 20 includes a plurality of conductive shanks 24a and 24b, a plurality of conductive cutting edges 23a and 23b, and an insulating member 25 that insulates between the cutting edges 23a and 23b. The shank 24a, 24b is a fixing member that fixes a chip (blade portion) having a cutting edge, and the cutting edge 23a, 23b is fixed to the shank 24a, 24b, respectively. The shank 24a, 24b may be connected by an insulating member 25 and formed integrally, and the cutting tool 20 may include three or more cutting edges. In the embodiment, it is assumed that the cutting edges 23a, 23b of the cutting tool 20 and the workpiece 30 are made of different materials and are different types of conductors, and that the workpiece 30 has a plurality of Cutting is performed simultaneously by the cutting edges 23a and 23b.

The processing device 1 includes, on a bed 2, a spindle housing 12 and a feed mechanism 21 that moves a cutting tool 20 relative to a workpiece 30. The cutting tool 20 is fixed to a tool fixing part 22, and the tool fixing part 22 is movably supported by the feeding mechanism 21. In the processing apparatus 1 shown in FIG. 1, the feed mechanism 21 has a mechanism for moving the tool fixing part 22 in the X-axis, Y-axis, and Z-axis directions, and moves the cutting tool 20 relative to the workpiece 30. . The sending mechanism 21 may include a motor and a ball screw for each axis. Note that in another example of the processing device 1, the cutting tool 20 may be fixed to the main shaft 10, and the feed mechanism may move the workpiece 30 relative to the cutting tool 20.

The main shaft 10 is rotatably supported by a main shaft housing 12. Specifically, metal or ceramic bearings 13a and 13b fixed to the main shaft housing 12 rotatably support the main shaft 10. The rotation mechanism 11 includes a mechanism for rotating the main shaft 10, and has a motor and a transmission structure for transmitting the rotational power of the motor to the main shaft 10. The transmission structure may include a V-belt and gears that transmit the rotational power of the motor to the main shaft 10. Note that the rotation mechanism 11 may be a built-in motor built into the main shaft 10 and directly drive the main shaft 10.

The processing apparatus 1 of the embodiment has a function of monitoring the state of processing using thermoelectromotive force generated at a plurality of contact points where the cutting tool 20 and the workpiece 30 come into contact while the main shaft is rotating. In the embodiment, the plurality of cutting edges 23a, 23b are contact members that contact the workpiece 30 during machining, and simultaneously process the workpiece 30 at the plurality of contact points 50a, 50b. At this time, the temperature of the contact points 50a, 50b becomes high, and a thermoelectromotive force (voltage) is generated between each of the plurality of cutting edges 23a, 23b and the workpiece 30. In the cutting tool 20, the conductive member 42a electrically connects the cutting edge 23a and the measuring section 45, and the conductive member 42b electrically connects the cutting edge 23b and the measuring section 45. The conductive member 42a and the conductive member 42b may be conductive wires whose exteriors are coated with an insulator, and may be disposed inside the shank 24a and the shank 24b, respectively. The measurement unit 45 measures the difference between the thermoelectromotive force generated between the cutting edge 23a and the workpiece 30 and the thermoelectromotive force generated between the cutting edge 23b and the workpiece 30.

Although the measuring section 45 is shown as being provided outside the cutting tool 20 in FIG. is preferred. In this case, the cutting tool 20 has a built-in measurement unit 45 that measures the difference in thermoelectromotive force generated between the plurality of cutting edges 23a and 23b during machining. Note that the measuring unit 45 may be provided in the processing device 1; in this case, the cutting tool 20 is provided with terminals connected to the ends of the conductive members 42a, 42b, and when the cutting tool 20 is attached to the processing device 1, Then, a wire extending from a measuring section 45 in the processing device 1 is connected to the terminal, and the measuring section 45 in the processing device 1 measures the difference in thermoelectromotive force generated at the plurality of cutting edges 23a and 23b.

The control unit 100 includes a spindle control unit 101 that controls rotation of the spindle 10 by the rotation mechanism 11, a movement control unit 102 that controls relative movement between the cutting tool 20 and the workpiece 30 by the feed mechanism 21, It includes an acquisition section 103 that acquires the voltage measured by the measurement section 45, and a monitoring section 104 that monitors the processing state using the voltage acquired by the acquisition section 103.

In general, most rotary tools have multiple cutting edges (called multi-edge tools), and fixed tools (typically turning tools) also have high efficiency and static/dynamic displacement reduction (also known as balance cutting, etc.). ), multi-edged tools are sometimes applied for chatter vibration stabilization. In the embodiment, a method is proposed in which the cutting edges of a multi-edged tool are insulated and the machining state is monitored from the difference in thermoelectromotive force generated at a plurality of contact points (cutting points) during machining.

Each element described as a functional block of the control unit 100 can be composed of a circuit block, a memory, another LSI, a CPU, etc. in terms of hardware, and can be composed of system software or a system loaded into memory. This is realized by an application program, etc. Therefore, those skilled in the art will understand that these functional blocks can be implemented in various ways using only hardware, only software, or a combination thereof, and are not limited to either.

The measurement unit 45 measures a thermoelectromotive force _VA generated due to the cutting temperature between the cutting edge 23a and the workpiece 30, and a thermoelectromotive force generated due to the cutting temperature between the cutting edge 23b and the workpiece 30. The difference V (=V _A −V _B ) in thermoelectromotive force V _B is measured. The acquisition unit 103 acquires the voltage V measured by the measurement unit 45, and the monitoring unit 104 uses the voltage V to monitor the cutting state.

FIG. 2(a) shows another example of the cutting tool 20. The cutting tool 20 shown in FIG. 2(a) is attached to the main shaft 10, and includes a conductive holder 26, a plurality of conductive cutting edges 23a and 23b, and an insulating member that insulates between the cutting edges 23a and 23b. 25. The holder 26 is a fixing member that fixes a tip (blade portion) having a cutting edge, and the cutting edges 23a and 23b are fixed to the holder 26. The cutting tool 20 shown in FIG. 2(a) is a boring multi-edge tool, and has two cutting edges 23a and 23b at positions with different diameters. When the cutting tool 20 has N cutting edges 23, it is preferable that adjacent cutting edges are arranged at rotational angle positions separated by (360°/N). In this example, the insulating member 25 is provided between the cutting edge 23a and the holder 26 to insulate the cutting edge 23a and the cutting edge 23b, but the insulating member 25 is provided between the cutting edge 23b and the holder 26. Good too.

The conductive member 42a electrically connects the cutting edge 23a and the measurement section 45, and the conductive member 42b electrically connects the cutting edge 23b and the measurement section 45. The conductive member 42a and the conductive member 42b may be conductive wires whose exteriors are coated with an insulator, and may be placed inside the holder 26, respectively. The measurement unit 45 measures the difference between the thermoelectromotive force generated between the cutting edge 23a and the workpiece 30 and the thermoelectromotive force generated between the cutting edge 23b and the workpiece 30. The measurement unit 45 may be provided inside the cutting tool 20 or may be provided outside the cutting tool 20.

FIG. 2(b) shows another example of the cutting tool 20. The cutting tool 20 shown in FIG. 2(b) is attached to the main shaft 10, and includes a conductive holder 26, a plurality of conductive cutting edges 23a and 23b, and an insulating member that insulates between the cutting edges 23a and 23b. 25. The holder 26 is a fixing member that fixes a tip (blade portion) having a cutting edge, and the cutting edges 23a and 23b are fixed to the holder 26. In the cutting tool 20 shown in FIG. 2(b), the cutting edge 23a is a countersinking edge, the cutting edge 23b is a drill, and a plurality of cutting edges 23a may be provided at different rotation angle positions. The insulating member 25 may be provided between the cutting edge 23a and the holder 26, but may also be provided between the cutting edge 23b and the holder 26.

The conductive member 42a electrically connects the cutting edge 23a and the measurement section 45, and the conductive member 42b electrically connects the cutting edge 23b and the measurement section 45. The conductive member 42a and the conductive member 42b may be conductive wires whose exteriors are coated with an insulator, and may be placed inside the holder 26, respectively. The measurement unit 45 measures the difference between the thermoelectromotive force generated between the cutting edge 23a and the workpiece 30 and the thermoelectromotive force generated between the cutting edge 23b and the workpiece 30. The measurement unit 45 may be provided inside the cutting tool 20 or may be provided outside the cutting tool 20.

3 and 4 below show the results of an experiment in which the effects of cutting speed and cutting thickness on cutting temperature were measured.
FIG. 3(a) shows the relationship between cutting temperature and tool angle when cutting at a plurality of cutting speeds. The cutting conditions for this experiment are as follows.
・Cutting style: Down cut, dry processing ・Work material: S45C
・Tool material: Cemented carbide ・Helix angle: 0 degrees ・Tool diameter: 20mm
・Feed amount: 0.1mm/blade/axial depth of cut: 6mm
・Radial depth of cut Rd: 0.5mm
When the angle at which the cutting edge is closest to the workpiece in down cutting is 360 degrees, the angle range at which the cutting edge processes the workpiece (tool angle range) is approximately 340 degrees to approximately 360 degrees. .
The experimental results in FIG. 3(a) show that the higher the cutting speed, the higher the cutting temperature.

FIG. 3(b) shows the relationship between cutting temperature and cutting speed when cutting with a plurality of radial depths of cut. As shown in FIG. 3(b), the relationship between cutting temperature and cutting speed follows a power law.

FIG. 4(a) shows the relationship between cutting temperature and tool angle when cutting with a plurality of feed rates. The feed rate is correlated with the cut thickness; as the feed rate increases, the cut thickness increases, and as the feed rate decreases, the cut thickness also decreases.
The cutting conditions for this experiment are as follows.
・Cutting style: Down cut, dry processing ・Work material: S45C
・Tool material: Cemented carbide ・Helix angle: 0 degrees ・Tool diameter: 20mm
・Cutting speed: 314.2m/min ・Axial depth of cut: 6mm
・Radial depth of cut Rd: 0.5mm
The experimental results shown in FIG. 4(a) show that the larger the feed rate, which is correlated with the cutting thickness, the higher the cutting temperature.

FIG. 4(b) shows the relationship between cutting temperature and feed rate. As shown in FIG. 4(b), it can be seen that the relationship between cutting temperature and feed amount follows a power law, and the relationship between cutting temperature and cutting thickness also follows a power law.

From the experimental results shown in FIGS. 3 and 4 above, it is confirmed that the cutting temperature is proportional to the power of the cutting speed and proportional to the power of the cutting thickness. In the machining process shown in FIG. 1, when the cutting speeds at the contact point 50a and the contact point 50b are compared, the cutting speed at the contact point 50a is faster because the contact point 50a is located on the outer side in the radial direction than the contact point 50b. . Further, since the cutting thickness depends on the shape of the cutting edge, the radial cutting depth, etc., the cutting thickness at the contact point 50a and the contact point 50b is generally different. Therefore, in the machining process shown in FIG. 1, the cutting temperature at the contact point 50a and the cutting temperature at the contact point 50b are different, and the measurement unit 45 measures the temperature difference.

In the cutting tool 20 shown in FIG. 1, when the cutting edge 23b vibrates and the cutting thickness increases or decreases, the cutting temperature also increases or decreases accordingly. The measurement unit 45 measures the difference between the thermoelectromotive force caused by the cutting temperature between the cutting edge 23a and the workpiece 30 and the thermoelectromotive force caused by the cutting temperature between the cutting edge 23b and the workpiece 30. Therefore, the measured voltage V oscillates due to an increase or decrease in the cutting temperature between the cutting edge 23b and the workpiece 30. When the monitoring unit 104 detects that the measured voltage V is vibrating based on the temporal change in the measured voltage V, it determines that at least one of the cutting edge 23a and the cutting edge 23b is vibrating.

Further, in the cutting tool 20 shown in FIG. 2A, when vibration occurs between the holder 26 and the workpiece 30, the cutting thickness by the cutting edge 23a and the cutting thickness by the cutting edge 23b each increase or decrease. At this time, since the rotation angle positions at which the cutting edge 23a and the cutting edge 23b are attached are different, the phases of the cutting thickness variation due to the cutting edge 23a and the cutting thickness variation due to the cutting edge 23b are different, and as a result, the contact point 50a The amplitude of the difference in cutting temperature at the contact point 50b increases. The monitoring unit 104 determines from the vibrating voltage V that at least one of the cutting edge 23a and the cutting edge 23b is vibrating with respect to the workpiece 30. Note that a predetermined threshold value Ath is set for the vibration amplitude of the voltage V (the absolute value of the difference between the maximum value and the minimum value), and the monitoring unit 104 determines that if the vibration amplitude of the voltage V is equal to or greater than the predetermined threshold value Ath, It may be determined that the cutting edge 23a and the cutting edge 23b are vibrating relative to the workpiece 30, that is, that a vibration problem is occurring.
As described above, the monitoring unit 104 determines whether at least one of the plurality of cutting edges 23 is against the workpiece 30 based on the time change of the difference in thermoelectromotive force (measured voltage V) generated at a plurality of contact points. It can be determined that it is vibrating.

In the cutting tool 20 shown in FIG. 1, when the cutting edge 23a is an R-bit, when the depth of cut decreases, the average cutting thickness decreases. Therefore, if the outer diameter of the workpiece 30 is smaller than the ideal value (planned value), the cutting temperature at the cutting edge 23a (the thermoelectromotive force between the tool and the workpiece is the average temperature of the contact area between them). ) is lower than the originally planned temperature. The monitoring unit 104 holds a reference value Vref that should be measured when cutting is performed on the ideally shaped workpiece 30, and the absolute value of (measured voltage V - reference value Vref) is If the predetermined value is exceeded, it may be determined that the error in the outer diameter of the workpiece 30 is larger than the allowable value. Alternatively, the monitoring unit 104 determines that the outer diameter of the workpiece 30 is larger than the upper limit of the allowable range when (measured voltage V - reference value Vref) exceeds the first predetermined value, and falls below the second predetermined value. It may be determined that the outer diameter of the workpiece 30 is smaller than the lower limit of the allowable range (at this time, the reference value Vref>0, the first predetermined value is a positive threshold, and the second predetermined value is a negative threshold). ). Note that when the outer diameter of the workpiece 30 is eccentric, the cutting thickness, which correlates to the depth of cut of the cutting edge 23a, increases or decreases in synchronization with the rotation of the main shaft. It may be determined from the vibration component that the outer diameter is eccentric.

In the cutting tool 20 shown in FIG. 2(b), if the cutting edge 23a is damaged or has greater wear than the cutting edge 23b, the sharpness of the cutting edge 23a has deteriorated. The cutting temperature at increases. In this case, the monitoring unit 104 can determine that an abnormality has occurred in the cutting edge 23a by detecting that the measured voltage V has increased. In particular, regarding defects, the monitoring unit 104 detects that the measured voltage V during monitoring drops momentarily (due to a temporary decrease in the cutting thickness due to the defect) and then increases immediately thereafter, so that the monitoring unit 104 It may be assumed that a defect has occurred.

FIG. 5 shows another example of the cutting tool 20. A cutting tool 20 shown in FIG. 5 is attached to a main shaft 10, and an insulating member insulates a conductive holder 26, a plurality of conductive cutting edges 23a, 23b, 23c, and the cutting edges 23a, 23b, 23c from each other. 25a and 25b. The holder 26 is a fixing member that fixes a tip (blade portion) having a cutting edge, and the cutting edges 23a, 23b, and 23c are fixed to the holder 26. The cutting tool 20 shown in FIG. 5 is a face milling tool, and a plurality of cutting edges 23a, 23b, 23c are provided at the same radial position but at different rotation angle positions. In this example, the insulating member 25a is provided between the cutting edge 23a and the holder 26, and the insulating member 25b is provided between the cutting edge 23b and the holder 26. It may be provided between.

The conductive member 42a electrically connects the cutting edge 23a and the measuring section 45a, and the conductive member 42b electrically connects the cutting edge 23c and the measuring section 45a. The measurement unit 45a measures the difference between the thermoelectromotive force generated between the cutting edge 23a and the workpiece 30 and the thermoelectromotive force generated between the cutting edge 23c and the workpiece 30. The conductive member 42c electrically connects the cutting edge 23c and the measuring section 45b, and the conductive member 42d electrically connects the cutting edge 23b and the measuring section 45b. The measurement unit 45b measures the difference between the thermoelectromotive force generated between the cutting edge 23c and the workpiece 30 and the thermoelectromotive force generated between the cutting edge 23b and the workpiece 30. The conductive members 42a, 42b, 42c, and 42d may be conductive wires whose exteriors are coated with an insulator, and may be arranged inside the holder 26, respectively. Note that even if another measurement unit 45 measures the difference between the thermoelectromotive force generated between the cutting edge 23a and the workpiece 30 and the thermoelectromotive force generated between the cutting edge 23b and the workpiece 30, good. Further, another cutting edge 23 may be provided at a position shifted by 180 degrees from the cutting edge 23c.

The monitoring unit 104 monitors the processing state based on the measurement voltage Va measured by the measurement unit 45a and the measurement voltage Vb measured by the measurement unit 45b. In the cutting tool 20 shown in FIG. 5, if the shapes of the plurality of cutting edges 23a, 23b, 23c are the same, and the radial positions of the plurality of cutting edges 23a, 23b, 23c are the same, each cutting edge is the same. Since machining is performed under these conditions, the cutting temperatures are the same. Therefore, if the measured voltage Va is not approximately zero, the monitoring unit 104 determines that an abnormality has occurred in either the cutting edge 23a or the cutting edge 23c, and if the measured voltage Vb is not approximately zero, the monitoring unit 104 determines that an abnormality has occurred in the cutting edge 23c. Alternatively, it may be determined that an abnormality has occurred in any of the cutting edges 23b. In this way, the monitoring unit 104 may monitor the processing state based on the magnitude of the difference in thermoelectromotive force generated at a plurality of contact points.

In the milling process shown in FIG. 5, the cutting thickness actually differs due to installation errors and shape errors of each cutting edge, and a temperature difference occurs between the contact points. Therefore, the monitoring unit 104 may determine that the cutting edge is eccentric by monitoring the measured voltages Va and Vb. At this time, the monitoring unit 104 estimates the difference in cutting thickness from the difference in thermoelectromotive force between adjacent cutting edges, and integrates the estimated value of the difference in cutting thickness between cutting edges arranged in the circumferential direction. By doing this, it is possible to estimate the comings and goings (each amount of eccentricity) of each cutting edge arranged in the circumferential direction.

Note that the boring tool shown in FIG. 2(a) may be provided with cutting edges 23 at three or more different radial positions. The monitoring unit 104 may use one cutting edge 23 as a reference edge and monitor the difference in thermoelectromotive force with other cutting edges 23, or monitor the difference in thermoelectromotive force between any two cutting edges 23, for example. may be monitored. The monitoring unit 104 may monitor the difference in thermoelectromotive force of different combinations of cutting edges 23 simultaneously, or may monitor them one by one by switching over time using a multiplexer or the like.

FIG. 6 shows an example of a circuit that measures voltages at five contact points. Note that the number of contact points is an example, and may be a number other than five. In this example, the thermoelectromotive force generated at each contact point and the series circuit of the resistance are connected in parallel, the five contact points are divided into two groups, and the weighted averages of the thermoelectromotive force in each group are V ₁ and V Measure the difference between _{the two} . In the example shown in FIG. 6, the voltage E _A is the thermoelectromotive force at the contact point A, the voltage E _B is the thermoelectromotive force at the contact point B, the voltage E _C is the thermoelectromotive force at the contact point C, and the voltage E _M is the thermoelectromotive force at the contact point M. Thermoelectromotive force and voltage E _N indicate the thermoelectromotive force at contact point N, and contact points A, B, and C are divided into a first group, and contact points M and N are divided into a second group.

第２グループにおける熱起電力の重み付き平均Ｖ_２は、以下の式２により導出される。

測定部４５は、差分の電圧Ｖ（＝Ｖ_１－Ｖ_２）を測定し、監視部１０４は、電圧Ｖを監視して、加工の状態を判定する。 The weighted average V ₁ of the thermoelectromotive force in the first group is derived by Equation 1 below.

The weighted average V ₂ of the thermoelectromotive force in the second group is derived by Equation 2 below.

The measuring unit 45 measures the voltage difference V (=V ₁ −V ₂₎ , and the monitoring unit 104 monitors the voltage V to determine the state of machining.

For example, if there is one cutting edge with high importance in machining among multiple cutting edges, the first group is made up of only that cutting edge, and the second group is made up of other plurality of cutting edges. This makes it possible for the monitoring unit 104 to monitor with high accuracy whether or not an abnormality has occurred at an important cutting edge.

FIG. 7 shows another example of the cutting tool 20. The cutting tool 20 shown in FIG. 7 is attached to the main shaft 10, and includes a conductive holder 26, a conductive cutting edge 23a, a conductive guide pad 27, and an insulation between the cutting edge 23a and the guide pad 27. member 25. The holder 26 is a fixing member that fixes a tip (blade portion) having a cutting edge, and the cutting edge 23a is fixed to the holder 26. The guide pad 27 is provided for the purpose of increasing straightness during deep hole machining, and scrapes the machined surface processed by the cutting edge 23a. In this example, the cutting edge 23a and the guide pad 27 are contact members that contact the workpiece 30 during machining, and contact the workpiece 30 at the same time. The insulating member 25 is provided between the guide pad 27 and the holder 26 to insulate the cutting edge 23a and the guide pad 27, but may be provided between the cutting edge 23a and the holder 26.

The conductive member 42a electrically connects the cutting edge 23a and the measuring section 45, and the conductive member 42b electrically connects the guide pad 27 and the measuring section 45. The conductive member 42a and the conductive member 42b may be conductive wires whose exteriors are coated with an insulator, and may be placed inside the holder 26, respectively. The measurement unit 45 measures thermal electromotive force caused by the cutting temperature at the cutting point where the cutting edge 23a cuts the workpiece 30, and thermal electromotive force caused by the friction temperature at the friction point where the guide pad 27 rubs the workpiece 30. Measure the power difference. The measurement unit 45 may be provided inside the cutting tool 20 or may be provided outside the cutting tool 20.

FIG. 8 shows another example of the cutting tool 20. The cutting tool 20 shown in FIG. 8 is attached to the main shaft 10, and includes a conductive holder 26, a conductive cutting edge 23a, a conductive brush 28, and an insulating member 25 that insulates between the cutting edge 23a and the brush 28. Equipped with. The holder 26 is a fixing member that fixes a tip (blade portion) having a cutting edge, and the cutting edge 23a is fixed to the holder 26. The brush 28 rubs the machined surface processed by the cutting edge 23a. In this example, the cutting edge 23a and the brush 28 are contact members that contact the workpiece 30 during machining, and contact the workpiece 30 at the same time. The insulating member 25 is provided between the brush 28 and the holder 26 to insulate the cutting edge 23a and the brush 28, but may be provided between the cutting edge 23a and the holder 26.

The conductive member 42a electrically connects the cutting edge 23a and the measuring section 45, and the conductive member 42b electrically connects the brush 28 and the measuring section 45. The conductive member 42a and the conductive member 42b may be conductive wires whose exteriors are coated with an insulator, and may be placed inside the holder 26, respectively. The measurement unit 45 measures a thermoelectromotive force caused by the cutting temperature at the cutting point where the cutting edge 23a cuts the workpiece 30, and a thermoelectromotive force caused by the friction temperature at the friction point where the brush 28 scrapes the workpiece 30. Measure the difference between. It is known that the rubbing temperature is determined mainly by the rubbing speed and the width in the rubbing direction, does not change significantly during cutting, and is generally much lower than the cutting temperature. Therefore, the measurement unit 45 can substantially measure the cutting temperature at the cutting edge 23a by measuring the difference between the thermoelectromotive force caused by the cutting temperature and the thermoelectromotive force caused by the abrasion temperature.

In the embodiment, when the holder 26 that fixes the cutting edge 23 rotates, the holder 26 may include a transmitting section that transmits the voltage measured by the measuring section 45 to the processing device 1. The transmitting unit may have a wireless communication function using a communication protocol such as the Bluetooth (registered trademark) protocol or the IEEE802.11 protocol, and converts the voltage measured by the measuring unit 45 from AD to the processing device 1 in real time. You may send it to Further, before AD conversion, an amplification section and an anti-aliasing filter section may be provided, and a power supply section (for example, a battery, a wireless power supply device) for these sections may be provided. Note that the holder 26 has a memory that stores the voltage measured by the measurement unit 45 together with time information, and the voltage and time information may be read from the memory after processing is completed.

The present disclosure has been described above based on the embodiments. Those skilled in the art will understand that this embodiment is merely an example, and that various modifications are possible to the combinations of these components and processing processes, and that such modifications are also within the scope of the present disclosure. .

A summary of aspects of the disclosure is as follows.
A processing device according to an aspect of the present disclosure includes: a rotation mechanism that rotates a main shaft to which a cutting tool or a workpiece is attached; a movement control unit that controls relative movement of the cutting tool with respect to the workpiece; The apparatus further includes a monitoring unit that monitors the state of machining using thermoelectromotive force generated at a plurality of contact points where the cutting tool and the workpiece come into contact.

According to this aspect, it is possible to monitor the machining state without providing a contact structure on the main shaft.

The monitoring unit may monitor the processing state using the difference in thermoelectromotive force generated at a plurality of contact points. At this time, the monitoring unit may monitor the processing state based on the time change of the difference in thermoelectromotive force generated at the plurality of contact points. Further, the monitoring unit may monitor the processing state based on the magnitude of the difference in thermoelectromotive force generated at a plurality of contact points.

A machining state monitoring method according to another aspect of the present disclosure includes a step of measuring a difference in thermoelectromotive force generated at a plurality of contact points where a cutting tool and a workpiece come into contact; and monitoring the machining state using the power difference.

According to this aspect, it becomes possible to monitor the processing state by using thermoelectromotive force generated at a plurality of contact points.

A cutting tool according to another aspect of the present disclosure includes a plurality of conductive contact members that come into contact with a workpiece when processing the workpiece, a fixing member to which the plurality of contact members are fixed, and a plurality of contact members that are connected to each other. The contact member includes an insulating member that insulates the contact member, and a conductive member that connects to at least one contact member.

By using the cutting tool of this aspect, the processing device can easily monitor the processing state using thermoelectromotive force generated at multiple contact points where the cutting tool contacts the workpiece. .

The cutting tool may include a measuring section that is connected to the conductive member and measures the difference in thermoelectromotive force generated in the plurality of contact members during machining. The cutting tool may include a transmitter that transmits the measured thermoelectromotive force difference. Note that the measuring section and/or the transmitting section may be provided in the holder or shank of the cutting tool.

The cutting tool may include a terminal connected to the conductive member and connected to a voltage measuring section in the processing device when the cutting tool is attached to the processing device. Further, the conductive member may be provided inside the fixing member.

DESCRIPTION OF SYMBOLS 1... Processing device, 10... Main spindle, 11... Rotating mechanism, 20... Cutting tool, 21... Feeding mechanism, 23a, 23b, 23c... Cutting edge, 24a, 24b... -Shank, 25, 25a, 25b... Insulating member, 26... Holder, 27... Guide pad, 28... Brush, 30... Work material, 31... Chuck, 42a, 42b , 42c, 42d... Conductive member, 45, 45a, 45b... Measuring section, 50a, 50b... Contact point, 100... Control section, 101... Spindle control section, 102... Movement Control unit, 103... acquisition unit, 104... monitoring unit.

Claims (10)

a rotation mechanism that rotates a main shaft to which a cutting tool or a workpiece is attached;
a movement control unit that controls relative movement of the cutting tool with respect to the workpiece;
a monitoring unit that monitors the machining state using thermoelectromotive force generated at multiple contact points where the cutting tool and the workpiece come into contact while the spindle is rotating;
A processing device equipped with. The monitoring unit monitors the processing state using a difference in thermoelectromotive force generated at a plurality of contact points.
The processing apparatus according to claim 1, characterized in that: The monitoring unit monitors the processing state based on a time change in a difference in thermoelectromotive force generated at a plurality of contact points.
The processing apparatus according to claim 2, characterized in that: The monitoring unit monitors the processing state based on the magnitude of the difference in thermoelectromotive force generated at the plurality of contact points.
The processing apparatus according to claim 2, characterized in that: A method for monitoring processing conditions, the method comprising:
measuring the difference in thermoelectromotive force generated at a plurality of contact points where the cutting tool and the workpiece come into contact;
monitoring the processing state using the difference in thermoelectromotive force generated at multiple contact points;
A method for monitoring machining conditions, comprising: A cutting tool,
a plurality of conductive contact members that come into contact with the workpiece when processing the workpiece;
a fixing member to which a plurality of contact members are fixed;
an insulating member that insulates between the plurality of contact members;
a conductive member connected to at least one contact member;
A cutting tool characterized by comprising: The cutting tool according to claim 6, further comprising a measuring section connected to the conductive member to measure a difference in thermoelectromotive force generated in a plurality of contact members during machining. The cutting tool according to claim 7, further comprising a transmitter that transmits the difference in the measured thermoelectromotive force. The cutting tool according to claim 6, further comprising a terminal connected to the conductive member, the terminal being connected to a voltage measuring section in the processing device when the cutting tool is attached to the processing device. . The conductive member is provided inside the fixing member,
The cutting tool according to any one of claims 6 to 9.

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