JPH06226507A - Cutting work device for forming cylindrical face on workpiece - Google Patents

Abstract

(57) [Abstract] [Purpose] To enable position adjustment of a cutting tool so as to form a desired accurate cylindrical machining surface in the axial direction and the circumferential direction. A tilt angle adjusting means for tilting the bite holder 4 is provided between a bite holder 4 to which a cutting bite 12 is attached and a supporting means 6 connecting the cutting bite 12. A stroke that detects the feed amount and rotation angle of the cutting tool 12.
The control pressure PS desired by the pressure adjusting means 20 to which the pressurized fluid is constantly supplied is supplied by the signal from the rotation angle detecting means 56.
Generate T. Applying it to the tilt angle adjusting means,
The cutting tool 12 is displaced by a unit of several μm. As a result, the cylindrical hole 18 formed in the work 16 and the outer surface of the rotating body can be precisely cut.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting device for forming a cylindrical surface on a work, and more specifically, to a cylinder for bearings, for example, inside a casing or a work similar thereto by a cutting tool. In a cutting device for forming a hole, a tilt angle adjusting means for inclining the tool holder is interposed between a tool holder to which the cutting tool is attached and a support means for connecting the tool holder, The present invention relates to a cutting working device in which an inclination angle adjusting means operates so as to follow a fluid pressure generated in a fluid pressure circuit.

[0002]

2. Description of the Related Art For example, an apparatus used for cutting a substantially cylindrical hole for mounting a bearing in a casing or a work object similar to the casing is disclosed in, for example, West German Laid-Open Patent Publication No. No. 3,726,276. The device is capable of precisely aligning a cutting tool mounted on a rotatable and radially adjustable tool head. In such a device, a tool correction system is adopted in order to ensure high dimensional accuracy. According to the correction system, the feed of the tool during cutting can be corrected within a range of several μm. A similar device is described in West German patent specification No. 1602962, and such a device is already known, but the device also has a function for suppressing a machining error on the system. In the above device, the position of the tool in the feed direction with respect to the work is displayed, and the outlet pressure of the pressure supply device that controls the adjusting device is changed accordingly. Therefore, according to this device, it is possible to reduce a machining error caused by a systematic mistake of the work machine or the machine tool. The deviation from the preset size is dealt with by the air pressure proportional to the magnitude of the error, which requires supplementary energy by compressed air. In addition, if the relationship between the feed path and the feed amount of the cutting tool in the direction perpendicular to it is linear, a spring or scale is used, and if it is not linear,
A measuring device using compressed air is used for scanning (scanning), and a guide device for measuring with the measuring nozzle is used.

[0003]

The known device described above is quite expensive but has a tolerance of 20 .mu.m to 3 .mu.m.
It can be suppressed to 0 μm or less. That is, for example, when a measurement nozzle body including a nozzle having a diameter of about 1 mm is used,
The error between the desired dimension and the machining dimension can be detected by the difference between the overhanging length of the measurement nozzle body and the machining hole diameter. However, the known system has a drawback that it is not possible to quickly detect a machining error and convert it into an appropriate correction pressure. Recently, a cutting machine having a hydraulic control adjustment system is also required to have high machining accuracy. Therefore, it is not uncommon to keep the permissible error of the machined hole to a few μm, and further, because of the increasing use of new cutting materials such as cemented carbide or polymerized crystal diamond, it is even more advanced. Cutting accuracy or processing speed has come to be required. Under these circumstances, there is a need for a precision machining device capable of finishing the axial and circumferential dimensions with an accuracy of μm when forming a cylindrical hole in a work. The precision machined surface produced in this manner is a mounting surface of a high load sliding bearing on which mechanical stress or thermal stress acts asymmetrically, for example, in a piston pin hole of an internal combustion engine. Required. West German Laid-Open Patent Publication No. 3,245,053 describes means for preventing an error in the axial direction and the circumferential direction when forming such a numerically accurate cylindrical hole, and has already been known. Has become. Of course, in this case a considerable amount of energy is required to change the position of the cutting tool. In one example, the tool holder is made of two different materials having different magnetostrictive properties, and the tool holder is bent via an electric coil connected to a frequency oscillator. In this case, there is a problem that it takes a long time to respond. In another example, although not described in detail, the bite holder held by the chuck has a non-uniform mass, and the mass is supported by the fluid bearing. Evenly arranged inlet openings are provided around the bite holder, through which fluids of different pressure levels are supplied. However, in this case, since the mass to be controlled is relatively large, there is a disadvantage that sufficient responsiveness cannot be obtained unless various improvements are made at high cost. The present invention has been made in view of the above problems, and an object thereof is to form a cylindrical hole or an outer surface of a rotating body on a workpiece that is extremely slightly deviated from a numerically accurate cylindrical shape in the axial direction and the circumferential direction. It is another object of the present invention to provide a cutting device capable of processing with a manufacturing error of several μm.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a cutting device for forming a cylindrical surface on a work by a cutting tool held by a cutting tool holding means. An inclination angle adjusting means for producing a relative angle between the bite holder and the supporting means is interposed between the supporting means for connecting the bite holder, and the inclination angle adjusting means applies the fluid pressure generated in the fluid pressure circuit. It is applied to a cutting work device that is designed to operate following each other. The feature is that, with reference to FIG. 1, the fluid pressure circuit 30 is connected with a pressure adjusting means 20 to which a fluid constantly pressurized from a fluid source 32 is supplied. On the other hand, a stroke / rotation angle detecting means 56 for detecting the feed amount and the rotation angle of the cutting tool 12 is installed.
Then, based on the detection signal from the stroke / rotation angle detecting means 56, the fluid supplied to the above-mentioned tilt angle adjusting means is changed to a desired control pressure by the pressure adjusting means 20. Stroke above
When outputting the detected feed amount and rotation angle of the cutting tool 12 from the rotation angle detecting means 56 as a digital signal, the control pressure P at the outlet of the pressure adjusting means 20.
A system controller 50 for controlling ST based on the output signal of the stroke / rotation angle detecting means 56 may be provided. Also, the stroke / rotation angle detection means 5
6 is compared with a preset value stored in advance in the computer means 52 of the system controller 50, and the difference value obtained by comparing the detected signal with the detected dimension value of the workpiece 16 produced immediately before. Then, the control pressure PST can be generated. The signal of the control pressure PST at the outlet of the pressure adjusting means 20 is fed back to the system controller 50 to control the pressure generating operation of the pressure adjusting means 20. As the pressure adjusting means, the overflow type valve mechanism 320 functioning as a variable throttle shown in FIG. 5 is adopted, and the fixed throttle 350 arranged upstream of the pressurized fluid from the fluid pressure circuit 30 (see FIG. 1) is used. Is supplied to the overflow type valve mechanism 320 via the overflow type valve mechanism 320.
Control pressure P caused by the position of the plunger 330 of the
ST is the stroke / rotation angle detection means 56 (see FIG. 1)
Can also be controlled according to the output signal of the. The outlet pressure of the overflow valve mechanism 320 is generated by the electrically controlled displacement of the plunger 330. The pressure adjusting means 20, 320 described above or 12 of FIG.
0 and the outlet pressure signal such as 220 in FIG.
The signal can be fed back to the signal processing means 54 including the D / A converter 74, the amplifier 76 and the A / D converter 78 in the system controller 50 shown in FIG.
The outlet pressure of the pressure adjusting means 20, 120, 220, 320 is transferred to the system controller 5 via the A / D converter 82.
It may be fed back to the computer means 52 at zero. The cutting tool holding means 2 has a base body 110 that is rotationally driven as shown in FIG. 7, and a displacement take-out body 1 that rotates together with the base body 110 to displace the cutting tool 12 in the radial direction.
It is possible to have the inclination angle adjusting means Bk1 composed of 11 and 11. The inclination angle adjusting means Bk1 includes a base body 110 including a thick plate portion 114 and a thin plate portion 113 elastically connected to the thick plate portion 114, and the base body 11 thereof.
It is constituted by a pressure motor DM1 having a displacement take-out body 111 capable of tilting by forming a fluid chamber 8 in a liquid-sealed state between the bite holder 4 and the displacement take-out body 111 at right angles. The length of the displacement extraction body 111 is set shorter than the length of the bite holder 4 so that the displacement amount of the displacement extraction body 111 that is firmly connected and tilted is smaller than the radial displacement of the cutting tool 12. It is good to do it. The fluid chamber 8 of the pressure motor DM1 is set to have a small volume, and the tilt angle adjusting means Bk1 is operated by supplying and discharging the pressurized fluid in an amount smaller than the volume of the fluid chamber 8 to move the displacement take-out body 111. It can be tilted. The displacement take-out body 111 has a disk shape which does not deform itself, and the center line 117 of the bite holder 4
This displacement take-out body 111 is provided through a thin plate portion 113 that is tiltable about an eccentric shaft 115 (see FIG. 8) that is displaced from the fulcrum, elastically deforms, and functions as a pressure-resistant wall.
Is firmly and liquid-tightly connected to the thick plate portion 114. The eccentric shaft 115 is an eccentric circular portion formed by an asymmetric ring concave portion 112 having an unequal width secured between the thin plate portion 113 and the thick plate portion 114 at a position eccentric from the center line 117 of the bite holder 4. It is good to put it.

[0005]

[Operation] Tool holder 4 with cutting tool 12 attached
Is rotated and is fed to open the cylindrical hole 18, the stroke / rotation angle detecting means 56
The relative position between the work 16 and the cutting tool holding means 2, that is, the feed amount of the cutting tool 12 and the rotation angle at that time are detected one by one. On the other hand, the pressure adjusting means 20 is constantly supplied with pressurized fluid from the fluid source 32 of the fluid pressure circuit 30,
In the pressure adjusting means 20, the cutting tool 12 whose outlet pressure is detected by the stroke / rotation angle detecting means 56.
The control pressure PST for obtaining a desired processing dimension is generated based on the feed amount of the sheet and the rotation angle at that time. When this control pressure PST acts on the inclination angle adjusting means, a relative angle change occurs between the tool holder 4 that holds the cutting tool 12 and the support means 6 that elastically connects and supports the tool holder 4. . Tool holder 4 is supporting means 6
If inclined with respect to, the cutting tool 12 is displaced in the radial direction. Since the change in the angle of the cutting tool holder 4 is slight, the cutting tool 12 is displaced within a range of several μm. That is, the control so that the cutting tool 12 is displaced by about 1 μm to 2 μm is realized by the control pressure PST. In this case, the processing accuracy is determined by the operation sensitivity of the stroke / rotation angle detecting means 56, but the control pressure PST is generated in a short time. In this way, the pressure adjusting means 2
The control pressure PST generated at zero is realized with a small amount of energy, so that the responsiveness for generating the control pressure is significantly improved. For example, not only when the diameter of the hole to be cut does not change in the axial direction, but also when the cross-sectional shape of the hole changes in the axial direction, it is possible to easily punch with high accuracy. The stroke amount and the rotation angle of the cutting tool 12 detected by the stroke / rotation angle detecting means 56 are output as digital signals, and the system controller 50 causes the pressure adjusting means 20 to obtain a desired control pressure PST based on the output signals. The command signal is output so as to generate. With such a digital signal, the stroke
The detection accuracy of the rotation angle detection means 56 becomes high, and the control pressure PST is generated based on the command calculated with excellent resolution. Therefore, even when the machined surface is the cylindrical hole 18 that is linear in the axial direction, or when the hole cross-sectional shape changes in the range of, for example, 500 μm or less, the outer surface of the rotating body is Linear or 5
Even in the case of a shape that changes in the radial direction within a range of 00 μm or less, it is possible to cut with an error of 1 μm to 2 μm or less. The detection signal from the stroke / rotation angle detecting means 56 is compared with a set value stored in advance in the computer means 52 of the system controller 50, and the pressure adjusting means 20 sets the desired control pressure P based on the difference value.
Generate ST quickly. Therefore, the cutting tool 12
The delay in the operation of the tilt angle adjusting means that causes a relative angle change between the bite holder 4 for holding and the supporting means 6 for elastically connecting the bite holder 4 is significantly shortened. Also, the stroke / rotation angle detection means 5
It is also possible to generate the control pressure PST based on the difference value obtained by comparing the detection signal in 6 with the detection dimension value in the workpiece manufactured immediately before. Also in this case, the operation response of the tilt angle adjusting means is excellent. That is, the control of the computer means 52 performs a quick correction operation based on the already detected error signal, and corrects the control pressure PST in a short time. If such a correction system is provided, it is possible to check the malfunction of the system itself and the mistake in the program. The control pressure PST at the outlet of the pressure adjusting means 20 is detected,
When it is fed back to the system controller 50, the control pressure PST generated by the pressure adjusting means 20 becomes a desired pressure with higher accuracy. If the pressure adjusting means is the overflow valve mechanism 320 and the pressurized fluid from the fluid pressure circuit 30 is supplied to the overflow valve mechanism 320 via the fixed throttle 350 arranged on the upstream side, The control pressure PST generated by the position of the plunger 330 of the flow valve mechanism 320 can be controlled to a value corresponding to the output signal of the stroke / rotation angle detecting means 56 with the least possible signal processing. When the outlet pressure of the overflow valve mechanism 320 is generated by the displacement of the electrically controlled plunger 330, the control pressure PST can be generated with a sufficiently high responsiveness. The signal processing means 54 comprises a D / A converter 74, an amplifier 76 and an A / D converter 78, and when the outlet pressure signal of the pressure adjusting means 20 is fed back to the signal processing means 54, a desired control is performed. The pressure PST can be more reliably generated in a short time. The outlet pressure of the pressure adjusting means 20 is
By feeding back to the computer means 52 of the system controller 50 via the A / D converter 82, the generated outlet pressure can be immediately corrected to the desired control pressure PST by the system controller 50. A base body 110 that is rotationally driven by the cutting tool holding means 2
By forming an inclination angle adjusting means composed of a displacement take-out body 111 which rotates with the base body 110 and displaces the cutting tool 12 in the radial direction, the cutting tool holding means 2 is placed on the support of the machine tool. Or spindle 131
(See FIG. 1) and can be driven to rotate.
The inclination angle adjusting means Bk1 is provided in the thick plate portion 114 and the thick plate portion 1
A base body 110 composed of a thin plate portion 113 elastically connected to 14 and a displacement take-out body 111 capable of forming a fluid chamber 8 in a liquid-sealed state between the base body 110 and tilting. The displacement motor 111 is constituted by a pressure motor DM1, and the bite holder 4 is firmly connected to the displacement extraction body 111 at right angles, and the displacement amount of the edge of the tilted displacement extraction body 111 is smaller than the radial displacement of the cutting bite 12. Since the length of the displacement take-out body 111 is set shorter than the length of the bite holder 4, the displacement take-out body 111 is
Even if the amount of tilting is extremely small, the cutting tool 12 mounted on the tip of the tool holder 4 can be displaced by a desired amount in the radial direction. The fluid chamber 8 of the pressure motor DM1 has a small volume, and the tilt angle adjusting means Bk can be provided by supplying and discharging the pressurized fluid in an amount smaller than the volume of the fluid chamber 8.
1, the pressure adjusting means 20 is operated.
When a predetermined control pressure PST is applied, the displacement take-out body 111 that tilts in response to the control pressure exhibits extremely good responsiveness that follows without substantially causing hysteresis. No large energy is required to generate the control pressure PST, and the response characteristics are improved, and even when the cross-sectional dimension of the machined surface changes in the axial direction,
It becomes possible to do the processing. The displacement take-out body 111 has a disk shape that does not deform itself, and is tiltable about an eccentric shaft 115 located at a position displaced from the center line 117 of the bite holder 4.
The displacement take-out body 111 is elastically deformed and the thick plate portion 11 is interposed via the thin plate portion 113 that functions as a pressure resistant wall.
4 is liquid-tightly and firmly connected, the natural frequency of the tilt angle adjusting means Bk1 is kept high. Therefore, the frequency of the control pressure of the supplied pressurized fluid is higher than the frequency, the resonance of the bite holder 4 is avoided, and the cutting accuracy is further improved. At the position where the eccentric shaft 115 is eccentric from the center line 117 of the bite holder 4, the thin plate portion 1 is
13 and the thick plate portion 114 are formed by the eccentric circular portion formed by the asymmetric ring concave portion 112 having a non-uniform width, the thin plate is formed when a predetermined control pressure acts on the fluid chamber 8. Deformation of the portion 113 on the wide side is facilitated, and reliable radial displacement of the cutting tool 12 can be realized even in the cutting tool holding means 2 having high rigidity.

[0006]

According to the present invention, the relative position between the work and the cutting tool holding means is adjusted by the control pressure at the outlet of the pressure adjusting means based on the detection signal of the stroke / rotation angle detecting means. This outlet pressure acts on the inclination angle adjusting means, and μ
A controlled feed of m units can be realized with sufficient responsiveness. In this case, the processing accuracy is determined by the operation accuracy of the stroke / rotation angle detecting means, but the pressure adjusting means is constantly supplied with pressurized fluid from the fluid pressure circuit, and the pressure adjusting means has an extremely small delay. It is possible to generate the control pressure that follows the output signal of the stroke / rotation angle detecting means. This makes it possible to obtain a cutting speed at which an expensive cutting material such as polymerized crystal diamond can be economically used even when the diameter of the cylindrical processed surface is small. A large amount of energy is not required to control the pressure adjusting means, and in that sense as well, the response characteristics of the tilt angle adjusting means can be improved. Of course, even when the cross-sectional dimension of the machined surface changes in the axial direction, the hole machining becomes easy. According to claim 2, the processing accuracy is further improved. This is because the stroke / rotation angle detecting means that outputs a digital signal has not only high detection accuracy but also high resolution. Therefore,
The inner surface of the cylinder or the outer surface of the cylinder that does not change in the axial direction, or the recessed hole or the outer surface of the rotating body that changes in the radial dimension within a range of not more than 500 μm, for example, is 1 μm to 2 μm.
It is possible to cut with an error of less than μm. According to the third aspect, the time delay between the detection by the stroke / rotation angle detecting means and the generation of the control pressure by the corresponding pressure adjusting means is significantly shortened. In this case, the detected error correction signal allows the program of the system controller to be automatically and appropriately corrected, and can also be notified. Therefore, it becomes possible to check the system mistake. According to the fourth aspect, the accuracy of the control pressure value generated by the pressure adjusting means is improved by feeding back the output signal of the pressure adjusting means. In claim 5 and claim 6,
Different configurations of the pressure adjusting means can be realized. The pressure adjusting means operates by direct electric control, and in particular, according to the structure of the overflow valve mechanism, the control pressure based on the output signal of the stroke / rotation angle detecting means is passed through as few signal converters as possible. Can be generated, and thus sufficient responsiveness can be obtained. Claims 7 and 8
In another example, according to, a feedback can be provided to the system controller from selected points in the pressure regulating means regarding signal flow. This improves the control accuracy as compared with the case where the control pressure is fed back in an analog manner. As in claim 9, when the cutting tool holding means is provided with an inclination angle adjusting means composed of a base body which is rotationally driven and a displacement take-out body which rotates together with the base body, the cutting tool holding means is provided in the machine tool. It can be driven to rotate by being mounted on a support or mounted on a spindle. According to the inclination angle adjusting means of the tenth to thirteenth aspects, the cutting tool can be made to follow the control pressure substantially without hysteresis. In this case, the natural frequency of the tilt angle adjusting means is obviously higher than the frequency of the control pressure supplied, resonance is suppressed, and accurate cutting operation is realized.

[0007]

The present invention will be described in detail below with reference to schematic drawings showing some embodiments. FIG. 1 is a schematic principle diagram showing a cutting device for forming a cylindrical surface on a work and a flow of control signals during the cutting. Reference numeral 2 in the drawing denotes a cutting tool holding means, which is provided with a cutting tool holder 4 to which a cutting tool 12 for making a hole is attached, and this cutting tool holder 4 has a parallel elastic joint mechanism not shown in detail. It is connected to the supporting means 6 via. Therefore, the casing of the cutting bite holding means 2 has a tilt angle adjusting means, which forms the fluid chamber 8, described later, as a parallel elastic joint mechanism. The fluid chamber 8 of the inclination angle adjusting means is pressure-controlled by the pressurized fluid supplied through the fluid passage 10. Therefore, the bite holder 4
The cutting tool 12 is tilted and controlled by a controlled pressure.
Can be displaced radially, for example up to about 500 μm. Since the structure of the inclination angle adjusting means is shown in West German Patent Specification No. 2,228,553, it will not be described in detail here, but an alternative thereof is shown in FIG. 7 described later. Reference numeral 14 is a main shaft, which is moved by driving means (not shown) when feeding in the direction of arrow X. Reference numeral 16 denotes a work for machining, in which a cylindrical hole 18 is formed by precision machining. In the cylindrical hole 18, a dimensional deviation deviating from a numerically accurate desired shape occurs in the axial direction and the circumferential direction. The axial displacement is as shown in FIG. 1, and the circumferential displacement is as shown in FIG. These deviations may occur up to about 500 μm, but it is necessary to suppress the allowable error in forming the cylindrical hole 18 to only a few μm. In FIG. 2, the alternate long and short dash line is a circle with accurate dimensions, and the solid line is an exaggerated illustration of the opened cylindrical hole 18. The system described below is used to control the tilt angle adjusting means described above in order to accurately dimension the cylindrical hole 18.
A pressurized fluid having a control pressure PST is supplied to the support means 6 via the rotary joint 19 and the fluid passage 10. The control pressure PST is generated by the pressure adjusting means 20 connected to the fluid pressure circuit 30 which constantly supplies the pressurized fluid. The fluid pressure circuit 30 comprises a pump as a fluid source 32, which supplies pressurized fluid to a pump conduit 36 via a check valve 34.
An accumulator 38 is provided immediately after the fluid source 32,
Pressure pulsations in the pump conduit 36 are suppressed. A pressure control valve 40 for adjusting the pressure of the pressurized fluid from the fluid source 32 is connected between the pressure control valve 40 and the return conduit 42 to the tank 44. The pressure adjusting means 20 is a multidirectional pressure valve that is electrically controlled, and adjusts the control pressure PST applied to the control pressure conduit 21 according to the magnitude of the current value applied to the solenoid 22. The electric signal is an output signal from the system controller 50 described below and is transmitted via the signal line 58. The system controller 50 has a computer means 52, a signal processing means 54, and a stroke / rotation angle detecting means 56, and the output signal transmitted through the above-mentioned signal line 58 is generated as follows. The relative position of the cutting tool 12 with respect to the work 16 in the feed direction X and the circumferential direction Θ (see FIG. 2) is determined by the linear glass scale 62 attached to the outer surface of the spindle 14 and the outer surface of the supporting means 6. Stroke / rotation angle detection means 5 for detection via the protruding disk 64
6 is always detected. The rotation angle of the disk 64 with respect to the spindle 14 is read by a photographic scanning means 66 schematically shown on the inner surface of the spindle 14. Then, the detection signals of the feed amount and the rotation angle of the cutting tool 12 are converted into digital signals through the A / D converters 68 and 70 and input to the computer means 52 having a large number of keyboards and screens. There is. Computer means 52 as described above
Then, various data are input using the keyboard, and the deviation of the position and the angle between the set dimension value input to the storage unit and the cutting tool 12 due to the data is detected by the tool holder 4.
It is obtained by comparing the feed amount and the phase difference, that is, the rotation angle. When a signal for adjusting the deviation is output, the bite holder 4 is tilted as described later to correct the deviation. The output signal of the computer means 52 has a D / A converter 74, an amplifier 76 and an adder / subtractor 78 connected in series.
Is input to the signal processing means 54 having The D / A converter 74 converts the digital signal from the computer means 52 into an applied current, and the degree of excitation of the solenoid 22 of the pressure adjusting means 20 is determined based on the detection signal from the stroke / rotation angle detecting means 56. It will be. Control pressure P
ST is fed back to the signal processing means 54 from the A / D converter 82 connected to the branch conduit 80 connected to the control pressure conduit 21. With the closed circuit formed thereby, the control pressure PST desired by the pressure adjusting means 20 can be reliably generated in a short time. The conducting wire 84 branched from the closed circuit is connected to the computer means 52, and the pressure signal via the conducting wire 84 is also inputted as a digital signal for the correction operation in the computer means 52. At the same time, a control sensor 86 for detecting the operation of the solenoid 22 is also provided in order to prevent a malfunction of the pressure adjusting means 20. This control sensor 86
Is fed back to the adder / subtractor 78 via the lead wire 88, whereby the movement of the spool of the pressure adjusting means 20 or the valve switching position is adjusted.

As is clear from the above description, in the principle circuit of FIG. 1, the control pressure PST is generated according to each output signal of the stroke / rotation angle detecting means 56. First, the spindle 14 is driven to rotate by receiving the feed and rotation command signal Y from the computer means 52, and the cutting tool 12
The bite holder 4 attached with is rotated and fed. The stroke / rotation angle detection means 56 detects the relative position between the work 16 and the cutting tool holding means 2, that is, the feed amount of the cutting tool 12 and the rotation angle at that time. This detection signal is sent to the computer means 52.
Is compared with a preset value stored in advance, and the degree of excitation of the solenoid 22 of the pressure adjusting means 20 is determined based on the difference value. On the other hand, the fluid pressure circuit 30 is connected to the pressure adjusting means 20.
The pressurized fluid is constantly supplied from the fluid source 32, and the pressure adjusting means 20 adjusts the valve opening degree according to the excitation degree of the solenoid 22 to obtain the control pressure PST that can obtain a desired processing dimension. Is generated. This control pressure PST is
Via the rotary joint 19, it acts on the inclination angle adjusting means in the cutting tool holding means 2 and is relatively positioned between the tool holder 4 holding the cutting tool 12 and the supporting means 6 connecting the tool holder 4. Causes an angle change. Since the cutting tool 4 is tilted with respect to the supporting means 6, the cutting tool 12 is displaced in the desired radial direction. Since the tool holder 4 has a slight inclination angle, the cutting tool 12 is displaced within a range of several μm. That is, the control so that the cutting tool 12 is displaced to about 1 μm to 2 μm is realized by the control pressure PST.
The processing accuracy depends on the operation sensitivity of the stroke / rotation angle detecting means 56, but the control pressure PST is generated in a very short time. As will be described later, since the fluid chamber 8 of the tilt angle adjusting means has a small volume, the fluid in the fluid chamber 8 can be sensitively affected by the pressure change by the fluid pressure circuit 30 and the pressure adjusting means 20, The excellent responsiveness of the tilt angle adjusting means is exhibited. In this way, the control pressure PST generated by the pressure adjusting means 20 is realized with a small amount of energy, so that the responsiveness for generating the control pressure becomes significantly high. For example, even when the diameter of the hole to be cut is constant in the axial direction, or even when the cross-sectional shape of the hole changes in the axial direction, the hole can be easily drilled with high accuracy. In this way, the tilt angle adjusting means operates by following the signal of the stroke / rotation angle detecting means 56 with good sensitivity. Therefore, when machining the cylindrical hole 18 in the work 16, the non-circularity and radius of the hole are processed. The length of the direction can also be modified. By the way, the stroke / rotation angle detecting means 56 outputs the detected feed amount and rotation angle of the cutting tool 12 as a digital signal, and the control pressure PST at the outlet of the pressure adjusting means 20 is converted into the stroke / rotation angle detecting means 56.
It is controlled based on the output signal of. When the system controller described above performs analog processing, the detection signal of the stroke / rotation angle detecting means 56 may be an analog signal, but if it is converted into a digital signal and output, then the stroke / rotation angle detecting means 56 may be used. The detection accuracy at 56 is high, and the control pressure PST can be generated based on the command calculated with an excellent resolution. By this, even if the cutting surface is a cylindrical hole linear in the axial direction described above,
In addition, even when the cross-sectional shape of the hole changes in the range of 500 μm or less, or even when the outer surface of the rotating body is cut linearly or in the shape of changing in the range of 500 μm or less, the error of 1 μm to 2 μm It can be processed. The stroke / rotation angle detecting means 5
6 detects not only the feed amount of the cutting tool 12 but also the rotation angle, but when the work 16 is rotated and cut without rotating the tool holder 4,
Only the above feed amount needs to be detected. In this case, if it is necessary to detect the rotation angle of the work 16,
The detecting means may be separately installed in the device for rotating the. In this way, when detecting the rotation angle of the work 16, when the inner surface of the hole or the outer surface of the rotating body is cut, the radial distance of the cutting tool 12 reaches a desired rotation angle. The cross section can be cut into an arbitrary shape by changing with. By the way, when the same machining is performed one after another, it is advisable to store the detection value by the stroke / rotation angle detecting means 56 of the workpiece produced immediately before in the computer means 52. In this case, the control pressure is generated until the detection signal of the stroke / rotation angle detecting means 56 reaches the stored value. By doing so, the response of the tilt adjusting means can be made quick. Then, the computer means 52 performs a quick correction operation based on the already detected error signal to correct the control pressure PST in a short time. If such a correction system is provided, the program of the system controller 50 can be automatically and appropriately corrected, and the system controller 50 can be informed of it to check the malfunction of the system itself or the mistake in the program. In the above, the control pressure at the outlet of the pressure adjusting means 20 is detected, and the detection signal is A
It is D / D converted and fed back to the signal processing means 54 and the computer means 52 of the system controller 50. The desired control pressure PST is generated in a short time by the feedback to the signal processing means 54, and the generated outlet pressure is immediately corrected to the desired control pressure PST by the system controller 50 by the feedback to the computer means 52. It When the detection value of the control sensor 86 attached to the solenoid 22 is input to the signal processing means 54 as the feedback to the system controller 50, it is desired more quickly than when the pressure signal is fed back. The control pressure PST can be generated.
By the way, the cutting tool holding means 2 is, as described later,
Inclination angle adjusting means Bk including a base body 110 (see FIG. 7) that can be driven to rotate and a displacement take-out body 111 that rotates together with the base body 110 to displace the cutting tool 12 in the radial direction.
1, the cutting tool holding means 2 is attached to the spindle 131 in the spindle 14 as shown in FIG. 1 or, although not shown, on a support provided separately for the machine tool. It can be mounted on.
Therefore, the cutting tool holding means 2 can be rotationally driven, and the operation based on the above-described control can be performed. Although the cutting accuracy depends on the detection accuracy of the stroke / rotation angle detecting means 56, the pressure adjusting means 20 always applies the pressurized fluid to the fluid pressure circuit 3.
Since the pressure is supplied from 0, the pressure adjusting means 20 generates the control pressure PST according to the output signal of the stroke / rotation angle detecting means 56 with a slight time delay.
As a result, the inclination angle adjusting means Bk1 is controlled by the pressure frequency of about 50 Hz to 80 Hz, and even if the diameter of the cylindrical hole 18 is small, a new cutting material such as cemented carbide or polymer crystal diamond is economical. A cutting speed that can be used for is realized. Further, the fluid chamber 8 of the tilt angle adjusting means has a small volume, and the fluid inside thereof operates the tilt angle adjusting means by supplying and discharging the pressurized fluid in an amount smaller than the volume of the fluid chamber 8, and therefore, A large amount of energy is not required to generate the control pressure PST in the pressure adjusting means 20, and in that sense, the response characteristic of the tilt angle adjusting means can be improved. Of course, even if the cross-sectional dimension of the machined surface changes in the axial direction, the machining can be performed.

FIG. 3 shows an example of a different pressure adjusting means 120, and the other structure is the same as that of FIG. A known 4-port 3-position servo valve is adopted as the pressure adjusting means 120 in this example. The servo valve 120 comprises a connection port for the pump conduit 36, a first port for the control pressure conduit 121, a second port 124 for return fluid and a tank connection port 126. The solenoid 22 is connected to the signal line 58 and displaces the piston valve of the servo valve 120. The tilt angle adjusting means Bk1 of FIG. 7 described later is a single-acting cylinder type, but when it has two oppositely acting fluid chambers like a double-acting cylinder type, it will not be described in detail, but this servo valve 120 Thus, the adjustment speed when tilting the bite holder 4 can be changed according to the magnitude of the signal in the signal line 58.

FIG. 4 shows another example of the pressure adjusting means 220, in which a pressure adjusting valve is used to change the outlet pressure of the control pressure conduit 221 via the signal line 58. Its outlet pressure PST acts on the rear face of the piston, via the control conduit 222, against the regulated control pressure. The adjusted control pressure is generated by the excitation of the solenoid 228 connected to the signal line 58, and the other configurations are the same as in the case of FIG. Control pressure PST
Reaches a predetermined value through the signal line 58, the piston in the pressure adjusting means 220 is moved by a spring (not shown) or the like as shown by an arrow in balance with the outlet pressure acting on the back surface of the piston. , Pump conduit 36
To decrease the flow rate of the pressurized fluid flowing from the control pressure conduit 221 to finally close the valve port. In this way, a predetermined control pressure PST is generated for the signal level on signal line 58.

FIGS. 5 and 6 show a second example of the cutting apparatus, which is shown very schematically. In this example, only the conversion of the signal in the pressure adjusting means 320 will be described. However, the control pressure generated by the position of the plunger to be described later is adjusted so as to correspond to the output signal of the stroke / rotation angle detecting means, as in the above-mentioned example. The pressure adjusting means 320 is connected to the fluid pressure circuit as in the previous example, and supplies the pressurized fluid to the rotary joint 19. Illustration of the stroke / rotation angle detecting means and the computer means is omitted. The feedback from the pressure adjusting means 320 to the system controller is also the same as in the case of FIG. 1, and their description is omitted. In this example, an overflow valve mechanism is adopted as the pressure adjusting means 320, and this overflow valve mechanism receives a control signal via a signal line 322 connected to the signal processing means 324. There is. Fluid source 326
It is the actuation of the plunger 330 in the overflow valve mechanism 320 that supplies pressurized fluid to the throttled supply conduit 328 and reduces the supply pressure PV to generate the control pressure PST in the control pressure conduit 321. It is done with. This plunger 330 has a front surface 335 to control the pressure chamber 3
52 to define a rear end of the casing 338. A compression spring 336 is interposed between the end flange 332 and the casing 338, and the plunger 33
0 is always biased to the left. The force generated by the solenoid 334 that receives the signal from the signal line 322 acts in the direction opposite to the force of the compression spring 336. Therefore, if the excitability of the solenoid 334 is changed, the short pipe 340 that is inserted into the casing 338 and communicates with the tank 344.
The distance between the inner opening of the and the plunger 330 can be continuously changed. Pressurized fluid is supplied to the control pressure chamber 352 via a fixed throttle 350 arranged on the upstream side. Therefore, when the operational relationship is properly balanced, the plunger 3 that functions as a variable diaphragm
A substantially linear relationship is established between the distance between the pipe 30 and the short pipe 340 and the pressure in the control pressure chamber 352. Therefore, the degree of throttling is changed by the change in the signal level of the signal line 322, and the control pressure PST can be changed quickly. This is because the desired control pressure PST depends on the position of the front surface 335 due to the displacement of the plunger 330. Therefore, the plunger 330 has a function of self-regulating the control pressure and also has a function of indirectly measuring the pressure. In this way, the overflow valve mechanism 32
Considering the operation of the plunger 330 at zero, the feedback for obtaining the control pressure PST is not frequently needed, and the exchange of electrical control signals is reduced,
The responsiveness at the time of generating the control pressure PST according to the detection signal of the stroke / rotation angle detecting means 56 is improved. That is, the control pressure PST, which is determined by the position of the plunger 330 of the overflow valve mechanism 320, can be controlled to a value corresponding to the output signal of the stroke / rotation angle detecting means 56 with as little signal processing as possible. However, it is possible to obtain sufficient responsiveness. Note that the signal line 322
If the control current at the position increases and the plunger 330 moves to the right, the throttle area between the front surface 335 and the short tube 340 decreases. This allows the control pressure in the control pressure conduit 321 connected to the pressure motor described below to be increased.

7 to 9 show an example of an inclination angle adjusting means Bk1 for inclining the bite holder 4 in accordance with the fluid pressure generated in the fluid pressure circuit. The pressure motor DM1 serving as the tilt angle adjusting means Bk1 converts the control pressure PST at the outlet of the pressure adjusting means into the radial displacement of the cutting tool 12 without time delay. The base body 110 in the figure constitutes the above-mentioned supporting means 6, and is a disc-shaped displacement take-out body 1 that functions as if to take out power.
11 is firmly attached orthogonally to the bite holder 4. The base body 110 is a flat rotary drive part having a circular cross section, and is divided into two parts, that is, a thin plate part 113 and a thick plate part 114 by a ring recess 112 in a region cut along a line VIII-VIII. . These plate portions 113 and 114 are connected by an eccentric circular portion 115 (see FIG. 8) which is an eccentric shaft that functions as a fulcrum for tilting described later. The thin plate portion 113 formed in the upper portion of the base body 110 by the asymmetric ring concave portion 112 having a non-uniform width has a shape like a closed sickle (see FIG. 9), and is different from the thick plate portion 114 below. It has a nice elastic connection. Then, the elastically deformable thin plate portion 113 also functions as a pressure resistant wall for the pressure motor DM1. As shown in FIG. 8, the wide part of the trimmed sickle is on the right and the narrow part is on the left. As shown in FIG. 7, the thin plate portion 113 includes a cylindrical protrusion 116 on the side opposite to the thick plate portion 114. The cylindrical protrusion 116 is provided concentrically with the center line 117 of the bite holder 4 and constitutes a part of the pressure motor DM1.
The base body 110 also functions as a fixing base for the pressure motor DM1 described below. The displacement take-out body 111 is integrated so as to hold the bite holder 4 provided at the center thereof, and a piston-like projection 123 is provided at the central portion on the opposite side of the bite holder 4. The piston-like protrusion 123 is fitted on the above-mentioned cylinder-like protrusion 116. Displacement extractor 111
Is firmly and liquid-tightly connected to the base body 110 by a screw 125 and an O-ring 127 provided between the cylindrical protrusion 116 and the piston-shaped protrusion 123. A fluid chamber 8 is defined between the piston-like protrusion 123 and the cylinder-like protrusion 116. The height is selected to be as small as possible in order not to cause an undesired effect such as the fluid inside being compressed. As described above, the volume of the fluid chamber 8 of the pressure motor DM1 is small, but the volume of the pressurized fluid supplied to tilt the displacement take-out body 111 is smaller than that volume. The cylinder-shaped protrusion 116 and the piston-shaped protrusion 123 constitute the pressure motor DM1. In this case, the thin plate portion 113 of the base body 110 has the displacement extraction body 111 and the screw 125 of the pressure motor DM1 as described above. It is firmly fixed by. The base body 110 has a hole 128 for fixing the base body 110 to the spindle 131 (see FIG. 1) and a positioning flange surface 129 near the outer edge thereof. The base body 110 has a fluid supply hole 130 that opens at the center of the flat disk-shaped fluid chamber 8 and has the fluid passage 10 shown in FIG.
It is provided so as to be continuous with. The displacement take-out body 111 of the pressure motor DM1 tilts with respect to the base body 110, which is a base for fixing, when the pressure changes. Fixed base 110
And the displacement extraction body 111 define a fluid chamber 8, and the fluid chamber 8 communicates with a fluid supply hole 130. As described above, the fluid chamber 8 is provided with the O-ring 127 for maintaining the liquid-sealed state despite the inclination of the displacement extraction body 111. That is, the inclination angle adjusting means Bk1 is in a liquid-sealed state between the base body 110 including the thick plate portion 114 and the thin plate portion 113 elastically connected to the thick plate portion 114, and the base body 110. And a displacement take-out body 111 capable of forming and tilting the fluid chamber 8 and the pressure motor DM1. The bite holder 4 is firmly connected to the displacement take-out body 111 at right angles so that the displacement amount of the edge of the tilted displacement take-out body 111 is smaller than the radial displacement of the cutting bite 12. Is shorter than the length of the bite holder 4.

The operation of the tilt angle adjusting means Bk1 described above is as follows. When the pressure of the pressurized fluid rises, the fluid flowing into the fluid chamber 8 tends to occupy a larger volume. In this case, the asymmetric ring recesses 1 of unequal width
The right portion in FIG. 9 of the thin plate portion 113, which is largely notched and easily deformed by 12, deforms more than the left portion. Therefore, the displacement extractor 111 is
With the eccentric shaft 115, which is eccentric to the center line 117 of the pressure motor DM1, as a fulcrum, it slightly tilts clockwise in FIG. This tilts the bite holder 4,
The cutting tool 12 is displaced in the radial direction. When the pressure of the pressurized fluid returns to the initial pressure, the thin plate portion 113 returns to its initial position by its own elasticity, and the bite holder 4 also returns to the initial position. The rigidity of this inclination angle adjusting means Bk1 depends on the size of its constituent parts, especially the thin plate part 113. As can be seen from the above, the displacement amount at the edge of the displacement extraction body 111 of the pressure motor DM1 is small,
The radial displacement of the cutting tool 12 attached to the tip of the inclined tool holder 4 is larger than that.
At this time, since the fluid chamber 8 has a small volume and the volume of the supplied fluid is also extremely small, the displacement take-out body 111 that tilts in response to the control pressure follows the movement substantially without causing hysteresis. Good response characteristics are exhibited. The displacement take-out body 111 has a disk shape that does not deform itself, and the center line 117 of the bite holder 4
The eccentric shaft 115 located at a position deviated from the eccentric shaft can be tilted. Since this displacement take-out body 111 is liquid-tightly connected to the thick plate portion 114 through the thin plate portion 113 that elastically deforms and functions as a pressure resistant wall, the natural frequency of the inclination angle adjusting means Bk1 is high. Maintained. This is because the pressure motor has a parallel elastic joint mechanism at the time of feeding the cutting tool 12, and has a tool holder that is displaced parallel to the center line 117, for example, in West German Patent Specification 2,034,601A2. Greater than the natural frequency in the described device and therefore the natural frequency of the tilt angle adjusting means Bk1 is higher than the frequency of the control pressure of the supplied pressurized fluid, resonance of the bite holder 4 is avoided, Cutting accuracy is further improved.

Incidentally, the bite holder 4 described above.
Instead of a firm connection between the displacement pick-up body 111 and the displacement pick-up body 111, it is also possible to connect the bite holder to the displacement pick-up body 111 by means of a tool change system with known construction. In addition,
In most of the above-described embodiments, a control pressure PST that effectively acts on the tilt angle adjusting means is provided by using a program for manually inputting a set value.
However, the control pressure PST may be generated based on the difference value obtained by comparing the detected dimension value and the set value in the workpiece manufactured immediately before.
Already mentioned above. Unlike the examples shown above, the cutting tool holding means can also be applied to tool holding devices such as milling cutters, precision drills and other blades. The cutting tool holding means according to the present invention is particularly useful in a machine tool having multi-axis CNC control.
In this case, a CNC control computer can be used to process the output signal of the stroke / rotation angle detecting means. Further, instead of the above-mentioned glass scale, a stroke / rotation angle detecting device which enables similar accurate measurement can be used. What makes this possible is a measuring system which acts electrically, optoelectronically or magnetically.

[Brief description of drawings]

FIG. 1 is a schematic principle view showing a cutting device and a signal transmission thereto in the first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a configuration diagram of different pressure adjusting means in the first embodiment.

FIG. 4 is a configuration diagram of another different pressure adjusting means of the first embodiment.

FIG. 5 is a schematic diagram of the principle of the second embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view of arrow VI in FIG.

FIG. 7 is a sectional view including a partial outer surface of a rotating cutting tool holding means.

8 is a sectional view taken along the line VIII-VIII of FIG.

9 is a sectional view taken along line IX-IX of FIG.

[Explanation of symbols]

2 ... Cutting tool holding means, 4 ... Tool holder, 6 ... Supporting means, 8 ... Fluid chamber, 12 ... Cutting tool, 16 ... Workpiece, 20 ... Pressure adjusting means (multidirectional pressure valve), 30 ... Fluid pressure circuit, 32 ... fluid source (pump), 50 ... system controller, 52 ... computer means, 54 ... signal processing means, 56 ... stroke / rotation angle detecting means, 74 ... D / A
Converter, 76 ... Amplifier, 78 ... Adder / subtractor, 82 ... A / D
Transducer, 110 ... Base body (rotational drive unit, fixing base), 111 ... Displacement extraction body, 112 ... Asymmetric ring recess, 113 ... Thin plate portion, 114 ... Thick plate portion, 115 ... Eccentric circular portion (eccentric shaft), 117 ... Center line, 120 ... Pressure adjusting means (4 port 3-position servo valve), 220 ... Pressure adjusting means (pressure adjusting valve), 320 ... Pressure adjusting means (overflow type valve mechanism), 324 ... Signal processing means, 326 … Fluid source, 330
... Plunger, 350 ... Fixed throttle, PST ... Control pressure, Bk1 ... Inclination angle adjusting means, DM1 ... Pressure motor.

 ─────────────────────────────────────────────────── ————————————————————————————————————— Inventor Hartmut Hirth Germany 6240 Königstein Steinbeek 14

Claims (13)

[Claims] 1. A cutting device for forming a cylindrical surface on a work by a cutting tool held by a cutting tool holding means, comprising: a tool holder having the cutting tool attached thereto; and a supporting means for connecting the tool holder. A tilt angle adjusting means for generating a relative angle between the bite holder and the supporting means is interposed between the two, and the tilt angle adjusting means operates so as to follow the fluid pressure generated in the fluid pressure circuit. In the cutting working device, the fluid pressure circuit is connected to a pressure adjusting means to which a fluid constantly pressurized from the fluid source is connected, and a stroke for detecting the feed amount and the rotation angle of the cutting tool. A rotation angle detecting means is provided, and the fluid supplied to the tilt angle adjusting means is adjusted to the above-mentioned pressure adjustment based on a detection signal from the stroke / rotation angle detecting means. A cutting device for forming a cylindrical surface on a workpiece, characterized in that the control pressure is changed by a node means. 2. The stroke / rotation angle detecting means outputs the detected feed amount and rotation angle of the cutting tool as a digital signal, and the control pressure at the outlet of the pressure adjusting means is the stroke / rotation thereof. The cutting apparatus for forming a cylindrical surface on a workpiece according to claim 1, further comprising a system controller which controls the output signal of the angle detecting means. 3. The detection signal from the stroke / rotation angle detecting means is compared with a preset value stored in advance in the computer means of the system controller, and the comb signal is compared with a detected dimension value of a work piece produced immediately before. The cutting apparatus for forming a cylindrical surface on a work according to claim 1 or 2, wherein the control pressure is generated based on a difference value obtained by the above. 4. The control pressure signal at the outlet of the pressure adjusting means is fed back to the system controller, whereby the pressure generating operation of the pressure adjusting means is controlled. A cutting device for forming a cylindrical surface on the work according to any one of claims 1 to 3. 5. The pressure adjusting means is an overflow valve mechanism functioning as a variable throttle, and the pressurized fluid from the fluid pressure circuit is transferred to the overflow valve mechanism via a fixed throttle arranged on the upstream side. The control pressure supplied, which is caused by the position of the plunger of the overflow valve mechanism, is controlled according to the output signal of the stroke / rotation angle detecting means. Item 5. A cutting device for forming a cylindrical surface on the work according to any one of Items 4. 6. The cutting for forming a cylindrical surface on a work according to claim 5, wherein the outlet pressure of the overflow valve mechanism is generated by an electrically controlled displacement of a plunger. Processing equipment. 7. The outlet pressure signal of the pressure adjusting means is
The cylindrical surface is provided on the workpiece according to any one of claims 4 to 6, which is fed back to a signal processing means including a D / A converter, an amplifier and an A / D converter in the system controller. Cutting processing equipment to form. 8. The outlet pressure of the pressure adjusting means is A / D
8. The cutting device for forming a cylindrical surface on a work according to claim 7, wherein the machining is fed back to a computer means in the system controller via a converter. 9. The cutting tool holding means includes tilt angle adjusting means composed of a base body that is rotationally driven and a displacement take-out body that rotates together with the base body and radially displaces the cutting tool. Claim 1 to claim 8
A cutting device for forming a cylindrical surface on the work described in any one of 1. 10. A fluid body in a liquid-sealed state between a base body including a thick plate portion and a thin plate portion elastically connected to the thick plate portion, and the base body. It is composed of a pressure motor having a displacement take-out body that forms a chamber and can be tilted, and a bite holder is firmly connected orthogonally to the displacement take-out body, and the edge displacement amount of the tilted displacement take-out body is cut. The work according to any one of claims 1 to 9, wherein the length of the displacement take-out body is set shorter than the length of the bite holder so as to be smaller than the radial displacement of the bite. A cutting device that forms a cylindrical surface on the. 11. A fluid chamber of the pressure motor has a small volume, and the inclination angle adjusting means is operated by supplying / discharging a pressurized fluid in an amount smaller than the volume of the fluid chamber, and the displacement take-out body. The cutting apparatus for forming a cylindrical surface on a work according to claim 10, wherein the cutting work can be tilted. 12. The displacement take-out body has a disk shape that does not deform itself, and is tiltable around an eccentric shaft that is displaced from the center line of the bite holder as a fulcrum. 12. The cylindrical surface is attached to the work piece according to claim 10 or 11, wherein the displacement take-out body is firmly connected to the thick plate portion in a liquid-tight manner via a thin plate portion that functions as a member. Cutting processing equipment to form. 13. The eccentric shaft is formed at a position eccentric from the center line of the bite holder, and is formed by an asymmetric ring concave portion 112 having an unequal width secured between the thin plate portion and the thick plate portion. The cutting device for forming a cylindrical surface on a work according to claim 12, wherein the cutting work is configured by a portion.