JPH01257547A - Rotary cutting machine - Google Patents

Abstract

PURPOSE:To suppress vibration by operating a cutter moving unit through a cutting condition modifying means and modifying the position of at least one cutter, thereafter advancing/retreating a movable cutter and performing small amount of cutting through a fixed cutter. CONSTITUTION:An AE sensor 54 fixed to an object 2 detects vibration during cutting work, then the vibration is processed through an AE processor 56 and a cutting condition setting computer 58 produces a necessary rotation coefficient and a feed speed coefficient based on the processed vibration. A macine com puter 60 obtains rotation and feed speed of a cutting tool 10 having fixed and movable cutters 22, 24 based on the rotation coefficient, feed speed coefficient and entire control information fed from a main computer 62, thus controlling spindle and X-axis motors 18, 20 and the like. At the same time, liquid pressure of a liquid pressure source 50 is switched, upon detection of vibration of the object 2, to retreat the movable cutter 24 and small amount of cutting is carried out only through the fixed cutter 22. By such arrangement, vibration can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary cutting device for cutting a workpiece using a rotary cutting tool, and particularly relates to a rotary cutting device equipped with a chatter vibration suppressing function. be.

Background of the Invention Some rotary cutting tools (hereinafter simply referred to as cutting tools) are equipped with a plurality of cutting edges. When cutting a workpiece using such a cutting tool, chatter vibration may occur due to elastic deformation of the cutting tool, the cutting device, or the workpiece. If cutting is performed under such conditions where chatter vibration is occurring, the cutting tool's cutting edge may suffer from minute chips, resulting in a shortened tool life or deterioration of the quality of the machined surface of the workpiece. occurs.

For this reason, the present applicant previously proposed a device for suppressing chatter vibration in Utility Model Application No. 193501/1983.

This device is configured to include chatter vibration detection means for detecting chatter vibration of a cutting tool, and cutting condition changing means for changing cutting conditions of the cutting tool based on a detection signal from the chatter vibration detection means. This changing means is adapted to change the rotational speed and feed rate of the cutting tool when chatter vibration is detected. Changing the rotation speed and feed rate changes the magnitude of cutting resistance acting on the cutting tool and its fluctuation period, reducing chatter vibration.
According to this device, the occurrence of chatter vibration can be automatically suppressed, and the occurrence of the above-mentioned problems due to chatter vibration can be avoided.

Problems to be Solved by the Invention It is an object of the present invention to provide a rotary cutting device having a function of effectively suppressing the occurrence of chatter vibration by changing cutting conditions by means different from the chatter vibration suppressing device described above. This was done as a challenge.

Means for Solving the Problems In order to solve the above problems, the present invention, as shown in FIG. b) a rotary drive device that rotates the cutting tool; (C) a feed device that moves the cutting tool and the workpiece relative to each other; and (d) chatter vibration detection means that detects chatter vibration that occurs during machining with the cutting tool. , (e
) A rotary cutting device comprising a cutting condition changing means for changing the cutting conditions of the cutting tool when chatter vibration is detected by the chatter vibration detecting means, in which at least one of the plurality of cutting edges of the cutting tool is formed. movable between a protruding position where at least one cutting edge performs cutting in the same manner as other cutting blades and a retracted position retreating from the protruding position, and moving the movable cutting edge forming part. A cutting blade moving device is provided, and the cutting condition changing means operates the cutting blade moving device to change the position of the at least one cutting blade.

A movable cutting blade, i.e. a movable cutting blade, can either not cut at all in the retracted position, or it can cut a smaller amount than another cutting blade which does not move, i.e. a stationary cutting blade. It is.

Actions and Effects If the movable cutting edge does not cut at all in the retracted position, it is the same as changing the number of cutting edges on the cutting tool, and the period of fluctuation of the cutting force acting on the cutting tool changes, or The fluctuating waveform becomes irregular, making it difficult for the cutting tool, cutting device, and workpiece to resonate, reducing chatter vibration. In a cutting tool having a plurality of cutting edges, the feed is sometimes expressed per cutting edge, and the feed per cutting edge is determined by the following equation (1).

Feed per l blade = feed speed/(rotation speed x number of teeth)・−・−・−・−(1)
For example, if you reduce the number of cutting edges, the feed per tooth will increase, and the cutting force per tooth will also increase, but since the number of cutting edges that receive the cutting force decreases, the force is applied to the entire cutting tool. The load will not be that high. Therefore, an increase in the feed per tooth due to a decrease in the number of cutting edges is sufficiently permissible, and even if the number of cutting edges is reduced, the feed per tooth can be adjusted to a size that is permissible by the cutting tool and rotary cutting device. There is no need to reduce the feed speed, and chatter vibration can be suppressed without reducing machining efficiency.

Even if the number of cutting edges is increased, the fluctuation cycle or fluctuation waveform of the cutting force acting on the cutting tool may change, and chatter vibration may be suppressed, but in this case, the feed per tooth becomes smaller. Since the cutting force per tooth is reduced, the overall load is as large as can be tolerated by the cutting tool and rotary cutting device, and there is no need to sacrifice machining efficiency by lowering the feed rate.

In addition, if the movable cutting blade performs a small amount of cutting even in the retracted position, the cutting resistance that the movable cutting blade receives decreases and the movable cutting blade does not perform cutting as described above. A phenomenon similar to occurs, and the occurrence of chatter vibration can be suppressed.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a diagram showing a rotary cutting device which is an embodiment of the present invention, and in the figure, 2 is a workpiece to be cut.

This workpiece 2 has a container shape with a deep hole 4,
It is fixed to a table 6 and the bottom of the deep hole 4 is cut by a cutting tool 10. The cutting tool 10 includes a hollow cylindrical tool body 12, and the axis of the tool body 12 extends in the vertical direction. The lower end of the tool body 12 is a large-diameter tip attachment part 14, while the upper end is gripped by a chuck 16. The chuck 16 is attached to a main shaft (not shown), and the main shaft is rotated by a main shaft motor 18 and a speed reduction device (not shown), thereby rotating the tool body 12. The main shaft motor 18 and the speed reduction device constitute a rotational drive device.

Further, the cutting tool 10 is moved in the X-axis direction, which is the left-right direction in FIG. It is moved in the Y-axis direction perpendicular to the X-axis direction in a horizontal plane by a feed screw device, and vertically moved by a Z-axis motor and feed screw device, which are also not shown. Feed is given by moving the cutting tool 10 in the X-axis direction or the Y-axis direction, and the X-axis motor 20 and the Y-axis motor and their corresponding feed screw devices each constitute a feed device. There is. Moreover, a depth of cut is provided by moving the cutting tool 10 in the Z-axis direction.

A plurality of chips are attached to the chip attaching portion 14. Some of these chips are fixed chips 22 fixed to the chip attachment part 14, and other chips are movable chips 24 movable in a direction parallel to the axis of the tool body 12. For example, when there are 8 chips in total, it is desirable to use 4 chips as movable chips, and when there are 9 chips in total, it is desirable to use 3 chips as movable chips. Third
As shown in the figure, a cavity 26 having a circular cross-sectional shape centered on the axis of the tool body 12 is formed in the tip mounting portion 14, and a circular piston 28 is inserted into the O-ring 2.
The piston 28 has hydraulic chambers 30 . 9 on both upper and lower sides of the piston 28 .
An atmospheric pressure chamber 32 is formed. A plurality of downwardly extending leg portions 36 (only one leg portion is shown in the figure) are provided on the outer circumference of the piston 28 at equal angular intervals.

A protrusion 38 is formed at the lower end of the leg 36 to project outward. The center side surface) is a plane parallel to the axis of the tool body 12, and the outer peripheral surface is a partial cylindrical surface having the same diameter as the outer peripheral surface of the piston 28. Further, the lower surface of the leg portion 36 is configured to be at the same height as the lower surface of the tip attachment portion 14 when the piston 28 is moved to the lower end position where it abuts the lower surface of the cavity 26. The leg portion 36 is formed to constitute a part of the tip attachment portion 14, and the movable tip 24 is fixed to the front side surface of the lower end portion in the cutting tool rotation direction.

A plurality of notches 40 are formed at equal angular intervals in the lower part of the tip attachment part 14 and open on the outer peripheral surface and the lower surface thereof and communicate with the cavity 26. A groove 42 (see FIG. 2) is formed in the front part. The three leg portions 36 are each fitted into the notch 40 so as to be slidable in the vertical direction. The leg portion 36 is in sliding contact with the inner circumferential surface of the cavity 26 on its outer circumferential surface, and has notches 40 on both side surfaces and the inner surface.
The piston 28 is guided in its vertical movement by sliding on the corresponding surfaces of the piston 28, thereby guiding the movement of the piston 28. Further, the protrusion 38 of the leg 36 is connected to the chip attachment portion 14.
The movable tip 24 is in a state facing the groove 42.

An appropriate number of grooves 44 (see FIG. 2) are formed between mutually adjacent notches 40 of the tip attachment portion 14, and the fixed tip is attached to the rear side surface of each groove 44 in the cutting tool rotation direction. 22 are fixed respectively. These fixed tips 22 are arranged around one circumference around the axis of the tool body 12.
The movable tip 24
is also −1 when the piston 28 is located at the lower end position.
- They are provided so as to be located around the circle. Note that although the chip mounting portion 14 is illustrated as an integral part,
In fact, Otoko is manufactured by being divided into multiple parts and then assembled as one.

[A liquid passage 46 communicating with the hydraulic pressure chamber 30 is formed in the Q main body 12. The liquid passage 46 is connected to a hydraulic pressure source 50 by a hose 48 (see FIG. 2), and by switching a directional control valve (not shown), the high pressure source 50 of the hydraulic source 50 is connected to the high pressure source 50.
and a low pressure port. Hydraulic pressure chamber 30
When the movable tip 24 is brought into communication with the high pressure port, the piston 28 is lowered and the movable tip 24 is moved together with the fixed tip 22 to an extended position for cutting the workpiece 2. As long as hydraulic pressure is supplied to the hydraulic pressure chamber 30, the movable tip 24 is maintained at the protruding position. Further, when the hydraulic chamber 30 is communicated with the low pressure port, the piston 28 is raised by the elastic force of the spring 52, and the movable tip 24 is moved away from the workpiece 2 to a retreated position where no cutting is performed. Piston 28. The hydraulic pressure source 50, spring 52, etc. constitute a cutting blade moving device.

An AE (acoustic emission) sensor 54 is attached to the workpiece 2 to detect chatter during cutting. The output signal of this AE sensor 54 is processed in an AE processor 56 and then output to a cutting condition setting computer 58. This computer 58 outputs to the machine computer 60 the rotation speed coefficient and feed speed coefficient necessary for setting the rotation speed and feed speed according to the cutting state. The machine computer 60 determines the rotation speed of the cutting tool 10 based on the above two types of coefficients supplied from the computer 58 and information from the main computer 62 that controls the entire processing line including the rotary cutting device.
Calculates the feed speed and performs control based on the calculation result.

The main computer 62 stores each cutting tool 1 along with control programs and various information necessary for cutting each workpiece 2.
A specific rotation speed command value and feed speed command value are stored in the machine computer 60, and commands corresponding to the types of the workpiece 2 and the cutting tool 10 are supplied to the machine computer 60. The machine computer 60 applies the cutting condition setting computer 58 to the supplied rotation speed command value and feed speed command value, respectively.
The rotation speed and feed speed are calculated by multiplying the rotation speed coefficient and feed speed coefficient supplied from the main shaft motor 18. Controls the rotation of the X-axis motor 20, etc.

Machine computer 60 also controls a directional valve that switches the supply of hydraulic pressure to hydraulic chamber 30.

These machine computers 60. main computer 6
2 is already known, so a detailed explanation will be omitted, and the cutting condition setting computer 58 will be explained below.

As shown in FIG. 4, the cutting condition setting combination 1-58 includes a CPU (central processing unit 1f) 66, a ROM (read-only, memory) 68. It includes a RAM (random access memory) 70 and a bus 72 that connects them. An input interface 74 is connected to the bus 72, to which the AE processor 56 is connected as well as a machine computer 60, and information supplied from the main computer 62 to the machine computer 60 is used to determine cutting conditions. The settings are supplied to the configuration computer 58 and configured as follows. Machine computer 60 is also connected to an output interface 76 which is connected to bus 72. Further, the RAM 70 is provided with a flag 78, and the ROM 68 contains a rotation speed specific to each cutting tool 10.

In addition to multiple stages of rotational speed coefficients and feedrate coefficients for calculating the upper and lower limits of feedrate and feedrate, the program for setting cutting conditions as shown in the flowchart in Figure 5 is stored. has been done.

Hereinafter, setting of cutting conditions will be explained based on this flowchart. Note that, at the start of the cutting process, hydraulic pressure is supplied to the hydraulic pressure chamber 30, the movable tips 24 are in the protruding position, and all the tips are in a state where the process is performed.

Furthermore, at the start of machining, the main computer 62 supplies the machine computer 60 with a rotation speed command value 2 and a feed speed command value according to the type of the cutting tool 10, and the cutting condition setting computer 58 is supplied with the rotation speed command value 2 and the feed speed command value via the machine computer 60. Based on this tool information, an appropriate rotation speed coefficient and feed rate coefficient are selected and supplied to the machine computer 60. The machine computer 60 calculates the rotation speed and feed speed based on these command values and coefficients, and calculates the rotation speed and feed speed of the main shaft motor 1B, χ
Control the rotation of shaft motor 20, etc.? Do Il+. The following description will be made assuming that the feed is provided by the X-axis motor 20.

First, step Sl (hereinafter abbreviated as Sl).

The same goes for other steps. ), initial settings are performed, and processes such as resetting the flag 78 are performed. Then, in S2, it is determined whether or not the flag 78 is set, but the determination result is No, and the output signal of the AE processor 56 is read in S3. This signal represents the cutting shape 1-imaginary, and it is determined in S4 whether or not chatter vibration is occurring based on this signal. S4 if chatter vibration is occurring.
The determination result is YES, and it is determined in S5 whether the feed per tooth is an appropriate value when the number of chips is reduced. 1 before reducing the number of chips
As mentioned above, the feed per blade depends on the number of fixed tips 22,
It is calculated from the feed speed and rotation speed read from the machine computer 60, but if the number of blades is reduced, the calculated result will be larger. When one movable chip 24 is disposed between two fixed chips 22, the fixed chip 22 on the rear side of the movable chip 24 (in the rotational direction of each chip 22° 24) has one The feed per tooth is doubled, or tripled if two movable tips 24 are disposed between one fixed tip 220.

The feed per tooth affects the roughness of the cut surface, and the comparison with the standard value A determines whether the feed per tooth affects the roughness of the cut surface and whether a good cut surface can be obtained even when the number of teeth is reduced. This is done by Note that for rough machining, the feed per tooth may be large, so the reference value A is set to a large value, and for finishing machining, the reference value (iA) is set to a small value.

(2) If the feed per blade is appropriate, it is smaller than the reference value A, the determination result in S5 is YES, and the number of blades is reduced in S6. That is, information instructing a reduction in the number of blades is supplied to the machine computer 60, and based on the information, the machine computer 60 stops the rotary cutting device, or does not stop the rotary cutting device, and operates the directional control valve to increase the hydraulic pressure in the hydraulic chamber 30. The state is changed to communicate with the low pressure port of a50. As a result, the movable tip 24 is raised all at once by the elastic force of the spring 52 and no cutting is performed, and the number of teeth is reduced, and the cutting tool IO
The occurrence of chatter vibration is suppressed by changing the fluctuation cycle or fluctuation waveform of the cutting force applied to the cutting force.

For example, when cutting a strip-shaped area with the same width as the diameter of the cutting tool 10, the cutting tool 10 has eight chips, in which every other four chips are movable chips. For example, when the movable tip is in the extended position, the cutting force changes as shown by the solid line in Figure 6, whereas when the movable tip is retracted and the number of chips is reduced, the cutting force changes as shown by the dashed line. As shown, the fluctuation period is doubled.

As a result, the forced vibration given to the cutting tool 10 by the cutting resistance deviates from its natural frequency, and the occurrence of chatter vibration is suppressed.

Further, if the cutting tool 10 has three movable tips among the nine tips, the cutting resistance changes as shown by the solid line in FIG. 7 when the movable tips are in the protruding position. On the other hand, when the cutting force is moved backward, the fluctuating waveform of the cutting resistance becomes irregular as shown by the broken line, and the fluctuating cycle becomes three times as large, suppressing the occurrence of chatter vibration.

In addition, in S6, a command to reduce the number of blades is issued, and a signal indicating that the number of blades has been changed is waited for, and after receiving that signal, the flag 78 is set in S7, and the program is started. Execution returns to S2.

On the other hand, if the feed per tooth is larger than the standard value A when the number of teeth is reduced, reducing the number of teeth to suppress chatter vibration may result in problems such as not being able to obtain an appropriate surface roughness. means undesirable. In that case, the determination result in S5 is No and the number of blades cannot be reduced, and S8, 3
9 is executed in the same manner as 33° S4. Since chatter vibration is currently occurring, the determination result in S9 is YES, and a rotation speed coefficient for reducing the rotation speed of the cutting tool 10 is selected in SIO. If the rotational speed of the rotary cutting tool 10 is reduced, the period of fluctuation of the cutting resistance corresponding to the rotational speed changes, and chatter vibration can be suppressed. Next, in 311, the feed per tooth is determined from the rotation speed obtained from the rotation speed coefficient selected by SlO, the feed rate set in the machine computer 60, and the number of teeth (in this case, the number of all chips). , is larger than the maximum allowable value. If the rotation speed is decreased, the feed per tooth increases, so it is compared with the allowable maximum value. If it is smaller than the allowable maximum value, the judgment result is NO and step 312 is executed, and the machine computer 60 is informed of the SIO The selected rotational speed coefficient is output. The machine computer 60 calculates the rotation speed based on this rotation speed coefficient, and controls the rotation of the main shaft motor 18 based on the rotation speed. In S12, after the rotation speed coefficient is output, the rotation speed of the spindle motor 18 is waited for to be controlled, and after receiving a control completion signal, the program execution returns to S2.

If the feed per tooth is larger than the maximum allowable value, the determination result in step 311 is YES, and a feed rate coefficient for reducing the feed rate is selected in S13. If the feed per tooth obtained by reducing the rotation speed is greater than the maximum allowable value, the feed rate is reduced to an appropriate value smaller than the maximum allowable value, and this feed rate coefficient is output to the machine computer 60 at 312 along with the rotation speed coefficient. The machine computer 60 calculates the rotation speed and feed speed from these rotation speed coefficients and feed speed coefficients, and based on the calculation results, the main shaft motor 18. Controls the X-axis motor 20. S1
2, after outputting the coefficient, the main shaft motor 18. The program waits for the control of the X-axis motor 20 to be completed, and after the control is completed, the program execution returns to S2.

If chatter vibration is not occurring, the determination result in S4 or S9 is NO, and in 314 it is determined whether the rotational speed of the rotary cutting tool 10 is at the upper limit value. If it is the upper limit value, it means that machining is being performed in a highly efficient state, and the program execution returns to S2 without any processing being performed. Further, if the rotation speed is not the upper limit value, the determination result in S14 is No. In this case, it means that the cutting efficiency is kept low even though chatter vibration is not occurring, and a rotation speed coefficient for increasing the rotation speed is selected in S15. 31
In step 6, 1 is calculated from the rotation speed obtained from the rotation speed coefficient selected in S15, the feed rate set in the machine computer 60, and the number of blades (the total number of chips).
The feed per tooth is determined, and it is determined whether it is smaller than the minimum allowable value. If the number of revolutions is increased, the feed per tooth becomes smaller, so it is compared with the allowable minimum value, and if it is an appropriate value, the judgment result in S16 is NO, and the feed value selected in S12 is 315. The rotation speed coefficient is output to machine computer 60.

In this case as well, in S12, after the coefficient is output, a change in the rotational speed is waited for, and after the change, the program execution returns to S2.

If the feed per time is too small, the determination result in S16 is YES, and a feed rate coefficient for increasing the feed rate is selected in S17. The feed rate coefficient as well as the rotation speed coefficient selected at 315 are output to machine computer 60 at S12. The machine computer 60 to which the rotational speed coefficient or rotational speed coefficient and feed rate coefficient are supplied performs calculations as described above to control the rotation or rotation and feed of the rotary cutting tool 10 so that cutting can be performed efficiently. Make it. In addition, S
At step 12, the program execution returns to step S2 after waiting for a change in the feed rate per revolution based on the output of the coefficient.

When chatter vibration is suppressed by reducing the number of blades, the next time step 82 is executed, the determination result is YES, so S3 to S5 are bypassed, and steps S8 and subsequent steps are executed. If the occurrence of chatter vibration cannot be suppressed by reducing the number of blades, the chatter vibration is suppressed by reducing the number of rotations. In addition, if chatter vibration still occurs after changing the rotation speed,
10-513 is executed to further change the rotation speed and suppress the occurrence of chatter vibration.

In this way, in the rotary cutting device of this embodiment, chatter vibration can be suppressed without reducing the machining efficiency by reducing the number of teeth. By reducing this, chatter vibration can be suppressed while obtaining a good finished surface, and various problems caused by chatter vibration can be avoided.

As is clear from the above explanation, in this example,
The AE sensor 54 constitutes chatter vibration detection means, and the ROM
6 The part that stores 86 of B, 36, 31 of cpU66
The part that executes 0 constitutes the cutting condition changing means.

In the above embodiment, the movable dip 24 can be moved to two positions, the protruding position and the retracted position, in a direction parallel to the rotation center line of the cutting tool.
Like the movable tip 80 shown in the figure, the tip may be provided so as to be adjustable between a protruding position and a retracted position in the radial direction of the cutting tool. A plurality of notches 86 are formed in the tip attaching portion 84 of the tool body 82, extending in the axial direction and opening on the outer circumferential surface and the lower surface of the tip attaching portion 84. A groove (not shown) is formed in the portion. These notches 8
A chip holding member 88 is fitted into each of the tips 6 and fixed thereto. The tip holding member 88 has a longitudinal shape 1, and its upper part is fixed to the depth mounting part 84 by bolts 90, and its lower part is movable in the radial direction of the tip mounting part 84 by elastic deformation. A movable chip 80 is fixed to the front side surface. A groove 92 with a T-shaped cross section is provided in the longitudinally intermediate portion of the tip holding member 88 to facilitate movement of the lower portion thereof, and is open on the inner surface and both side surfaces facing in the circumferential direction of the tip mounting portion 84. It is being

Inside the tip mounting portion 84, the cross-sectional shape is a tool body 82.
A bottomed hole 94 is formed in a circular shape centered on the axis of the chip mounting portion 84 and opens at the lower surface of the chip mounting portion 84, and a portion of the peripheral wall of the bottomed hole 94 corresponding to the notch 86 has a radius. A through hole 96 extending in the direction is formed. A protruding member 98 is fitted into each through hole 96 so as to be slidable in the axial direction. This protruding member 98 has a through hole 96
An inclined surface 100 directed toward the center of the lower bottom hole 94 is formed at the end of the bottom hole 94 . In addition, a container-shaped piston 10 is provided in the bottomed hole 94.
2 is slidably fitted with its opening facing downward and kept liquid-tight by an O-ring 104. As a result, a hydraulic chamber 1 is formed between the piston 102 and the bottomed hole 94.
06 is formed, and the piston 102 is lowered by supplying hydraulic pressure from the liquid passage 108. At a portion of the lower end of this piston 102 corresponding to the protruding member 98, an inclined surface 110 having an inclined surface corresponding to the inclined surface 100 is provided.
is formed and engaged with the inclined surface 100.

On the other hand, the opening of the bottomed hole 94 is closed by a stepped spring receiver 112 screwed together, and a disc spring 116 is disposed between the large diameter portion 114 and the piston 102 to raise the piston 102. It is biased in the direction of Hydraulic pressure chamber 106
When the piston 102 is in communication with a low-pressure port of a hydraulic pressure source (not shown), the piston 102 is biased by the disc spring 116 and is at the rising end position in contact with the bottom surface of the bottomed hole 94, and the protruding member 98 is in contact with the tip mounting portion. Through hole 96 from the outer peripheral surface of 84
It is in a retracted position where it is retracted inward and does not engage with the chip holding member 88. Further, as shown by the solid line, the movable tip 80 is located closer to the axis of the tool body 82 than the fixed tip 118 shown by the two-dot chain line, and is in a retracted position where no cutting is performed. From this state, when the hydraulic chamber 106 is brought into communication with the high pressure port of the hydraulic pressure source and the piston 102 is lowered, the protruding member 98 is pushed out of the tip attachment part 84 from the through hole 96 by the action of the slope, and the tip Push retaining member 88 outward. As a result, the lower part of the tip holding member 88 is moved outward, and the movable tip 80 is moved outward from the fixed tip 11.
Similarly to 8, it is moved to the protruding position where cutting is performed. Projecting member 98. The piston 1023, disc spring 116, etc. constitute a cutting blade moving device.

A notch 120 is formed in a portion of the outer peripheral surface of the piston 102 on the opposite side of the O-ring 104 from the hydraulic pressure chamber 106, and a sensor 122 is embedded in a portion of the tip mounting portion 84 adjacent to the notch 120. has been done. The sensor 122 detects the outer peripheral surface of the piston 102, and the notch 1
20, the magnitude of the detection signal changes as the piston 102 moves, and the position of the piston 102 can be detected. Thereby, the position of the movable tip 80 that is moved based on the movement of the piston 102 can be detected, and based on the detection result, the position of the movable tip 80 can be detected.
By controlling the supply and discharge of hydraulic fluid to 6,
The movable tip 80 can be positioned at any position between the extended position and the retracted position. Therefore, the cutting amount of the movable tip 80° can be made smaller than the cutting amount of the fixed tip 118 to suppress the occurrence of chatter vibration, or the cutting amount of the movable tip 80 can be selected depending on the degree of chatter vibration.
By changing the cutting amount of the movable tip 80 in stages,
The occurrence of chatter vibration can be suppressed only by changing the position of the movable chip 80.

In addition, in each of the above embodiments, the movable tip 24.80
Although the movable chips were designed to move all at once, they may be provided so as to be movable individually, and a moving device as shown in FIG. 8 may be provided for each movable chip so that the movable chips can be moved individually.

Moreover, the movable tip 24 was supposed to move in the axial direction of the cutting tool 10, and the movable tip 80 was supposed to move in the radial direction, but by moving in a direction inclined with respect to the axial center, the movable tip 24 can be moved to the protruding position and the retreating position. You may also move it to .

Furthermore, in the above embodiment, the tips 22, 24, 80, 118 separate from the tool body 12.82 constitute the cutting blades, but a plurality of cutting blades are provided in a part of the tool body 12.82. The parts forming at least one of the parts may be moved.

Furthermore, in the above embodiment, chatter vibration was suppressed by reducing the number of blades, but chatter vibration may be suppressed by increasing the number of blades, and The chatter vibration may be suppressed only by moving the movable cutting blade without changing the above.

Furthermore, the present invention can be applied to a rotary cutting device that processes a workpiece by moving a cutting tool in the axial direction.

Although not illustrated in detail, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the configuration of the present invention. FIG. 2 is a system diagram showing a rotary cutting device which is an embodiment of the present invention. FIG. 3 is a front sectional view showing the main parts of the cutting tool of the rotary cutting device. FIG. 4 is a block diagram showing a cutting condition setting computer of the rotary cutting device. FIG. 5 is a flowchart showing the program stored in the ROM of the computer. FIG. 6 is a graph showing the cutting resistance when the movable chips are at the protruding position and when the movable chips are at the retracted position, respectively, when every other movable chip is used as a movable chip. FIG. 7 is a graph showing the cutting resistance when the movable tip is at the protruding position and when the movable tip is at the retracted position, when one out of three tips is a movable tip. FIG. 8 is a front sectional view showing a main part of a cutting tool of a rotary cutting device according to another embodiment of the present invention. 2: Workpiece 10: Cutting tool 18; Main shaft motor 20: χ-axis motor 22: Fixed tip 24
: Movable balance 28: Piston 30: Hydraulic pressure chamber 50: Hydraulic pressure source 54: AE sensor 80: Movable tip 9th: Protruding member 102: Piston
116: Belleville spring 118: Fixed chip 120: Notch 122; Sensor

Claims (1)

[Claims] A rotary cutting tool that includes a plurality of cutting blades and is rotatable around a single axis, a rotary drive device that rotates the rotary cutting tool, and a relative movement between the rotary cutting tool and a workpiece. a feeding device; a chatter vibration detection means for detecting chatter vibration occurring during machining by the rotary cutting tool; and a cutting condition changing means for changing cutting conditions for the rotary cutting tool when chatter vibration is detected by the chatter vibration detection means. A rotary cutting device comprising: a protrusion in which the at least one cutting blade cuts a portion forming at least one of the plurality of cutting blades of the rotary cutting tool in the same manner as the other cutting blades; and a retracted position that is retracted from the protruding position, and a cutting blade moving device that moves the movable cutting blade forming portion, and the cutting condition changing means is configured to include the cutting blade moving device. A rotary cutting device characterized in that the rotary cutting device is operated to change the position of the at least one cutting edge.