JPH11156601A - Step vibration cutting method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting method and device for improving a tool life, and effective in cutting work for high-hard and cutting-difficult material, etc., by eliminating a collision to the addendum of a tool to suppress tipping, and also unnecessary rubbing of the addendum at the time of cutting, while displaying a working accuracy characteristic equal to a vibration cutting method. SOLUTION: By arranging a striking means or an exciting part 4 on the rear, with a clearance equal to or more amplitude provided, to a tool 1 or a holder 1a for holding the tool 1, to vibrate the striking means or the exciting part 4; the following is repeated: that the tool 1 or the holder 1a for holding the tool 1 is tappedly driven periodically in a cutting or feeding direction, to make cutting in only a vibration-progressing stroke having no clearance C; that the cutting is rested, with a tool addendum 2 left in a condition, where the tool addendum 2 is contacted intactly, to a cutting point in the vibration retreating stroke of the striking means or the exciting part 4; and that the cutting point is restruck to the tool 1 or the holder 1a for holding the tool 1 to be cut when the striking means or the exciting part 4 is altered to the vibration progressing stroke; thereby creating a steplike addendum locus to perform cutting intermittently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a step vibration cutting method and apparatus.

[0002]

2. Description of the Related Art A vibration cutting method (see Japanese Patent Publication No. 36-18897) is known as one of precision cutting methods. In this vibration cutting method, as shown in FIG. 1, a tool is regularly vibrated in a cutting direction at a constant cycle (for example, a sine waveform),
This is a method in which cutting is performed intermittently with the cutting speed Vw satisfying Vw <2πAF (A: amplitude, F: frequency).
That is, as shown in FIG. 2, the feature is that the cutting is performed only at the time of forward movement of the tool indicated by the bold line, and at the time of retreat, the cutting edge is separated from the cutting point of the workpiece. According to this prior art, it is said that a tool or a workpiece can be apparently made rigid in terms of vibration engineering, an effect of preventing elastic deformation can be obtained, and an effect of reducing generation and heat generation of a component edge can be obtained. ing. Specific methods of implementing this prior art include a method using a low-frequency vibration region and a method using vibration in an ultrasonic region. According to these methods, turning, planing, milling, tapping, broaching, and the like. It is said that precision processing is possible in various processing modes such as processing.

[0003] However, in this prior art, an active cutting edge which repeats forward-backward cutting is performed while vibrating in a cutting direction.
Since the trajectory of the cutting edge is an impactful intermittent cutting in which forward and backward repetitions are repeated every cycle T, a cutting mechanism in which the cutting edge collides with the workpiece is repeated. For this reason, there is a problem that chipping easily occurs on the cutting edge of the tool due to the impact. In addition, since the tool cutting edge rubs against the machined cutting surface during non-cutting shown by a thin line in FIG. 2, there is a problem that the cutting edge wear is promoted. Due to these causes, when cutting hard materials such as hardened steel and pre-hardened steel and SUS-based materials, Ni-based alloys, and cutting of difficult-to-cut materials with severe heat generation, such as Ni-based alloys and titanium-based alloys. The tool life tends to be extremely short, the cutting cost is extremely high, and the machining efficiency is deteriorated due to the trouble and time loss of tool replacement.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems. A first object of the present invention is to provide a machining accuracy characteristic comparable to a vibration cutting method. An object of the present invention is to provide a non-rolling type cutting method capable of suppressing chipping by eliminating collision of a tool with a cutting edge and suppressing unnecessary rubbing of the cutting edge during cutting, thereby improving tool life. A second object of the present invention is to provide a cutting device capable of achieving the above-mentioned effects with a relatively simple structure. A third object of the present invention is to provide a milling type cutting method capable of exhibiting machining accuracy characteristics comparable to the vibration cutting method, while eliminating collision with the cutting edge of the tool, suppressing chipping and improving tool life. Is to provide. A fourth object of the present invention is to provide a cutting device that can achieve the above-mentioned effects with a relatively simple structure.

The method of the present invention is extremely effective not only for machining a work piece of ordinary material but also for cutting a hard material or a difficult-to-cut material, and the cutting speed Vw is Vw <2πAF (A: amplitude, F: Frequency) or the feed rate fw satisfies fw <2πAF (A: amplitude, F: frequency), for example, in addition to planing and shaping, turning, drilling, end milling , Tapping,
It is applied to all cutting processes such as reaming and broaching. The vibration used in the method of the present invention has a vibration frequency of 1
２０００2000 Hz, low frequency vibration range of about 3 mm or less, vibration frequency of 10 to 500 KHz, amplitude of 50
An ultrasonic range of about μm or less will be applied.

[0006]

In order to achieve the first object, a step vibration cutting method according to the present invention uses a striking means or a vibrating portion for a tool or a holder holding the tool so that the clearance is equal to or greater than both amplitudes. The tool or the holder holding the tool is cut by setting the cutting speed Vw to Vw <2πAF (A: amplitude, F: frequency) while oscillating the striking means or the vibrating section in the cutting direction. The machine periodically taps in the direction to perform cutting only during the pre-vibration process where the clearance has been lost, and pauses the cutting while leaving the tool in contact with the cutting point during the retraction stroke of the striking means or the vibrating section. When the striking means or the vibrating section has turned to the pre-vibration advance position again, it is necessary to re-collide with the tool or the holder holding the tool to generate a step-like cutting edge trajectory for performing the cutting and perform intermittent cutting. It is set to.

In order to achieve the second object, a step vibration cutting apparatus according to the present invention comprises a tool held movably only in a cutting direction or a holder holding the tool, and a tool or a holder holding the tool. In contrast, the gist of the present invention is to include a striking means or a vibrating section arranged rearward with a clearance of both amplitudes or more in the cutting direction, and a means for applying vibration to the striking means or the vibrating section.

According to the present invention, in order to achieve the third object, when cutting is performed by a milling tool, the rear end of the holder holding the milling tool and the circumferential vibration applying means (or the milling tool) may be used. A clearance of at least both amplitudes is provided between the shank and the holder to which the circumferential vibration is transmitted, so that the rotation of the milling tool in the circumferential direction is allowed up to this clearance,
When the circumferential vibration imparting means (or holder) moves in the forward rotation direction in each vibration, cutting is performed with a rolling tool due to the loss of the clearance, and the circumferential vibration imparting means (or holder) moves in the reverse rotation direction. Occasionally, the cutting is paused by leaving the milling tool at the cutting point by the clearance, and when the circumferential vibration applying means (or the holder) starts to move in the forward direction again, the holder (or the shank) is turned off.
The point is that intermittent cutting is repeatedly performed by repeatedly generating a step-like tool edge trajectory for performing cutting with a rolling tool by recolliding with the cutting tool.

In order to achieve a fourth object, the present invention provides a device for impacting provided on a circumferentially oscillating main shaft, a tongue portion provided at a rear portion of a holder for holding a milling tool, and a tongue portion provided on the impacting means. The clearance between the outside and the outside of the section is provided with a clearance of both amplitudes or more.

In order to achieve a fourth object, the present invention provides a device in which a rolling tool having a tongue portion at the rear is held by a holder on a circumferentially vibrating main shaft coupled to a means for applying low-frequency vibration. The holder is provided with a pair of striking means or a vibrating portion for providing a clearance of at least both amplitudes with the outer surface of the tongue portion.

In order to achieve the third object of the present invention, in performing cutting by a milling tool, a striking means or a vibrating portion is provided to the milling tool or a holder holding the same with a clearance equal to or greater than both amplitudes. Is provided at the rear side, and the milling tool or the tool is held by vibrating the striking means or the vibrating portion in the feed direction and setting the feed speed fw to fw <2πAF (A: amplitude, F: frequency). The holder is periodically beat-driven in the feed direction, cutting is performed only during the pre-vibration process where the clearance is lost, and the tool is kept in contact with the cutting point during the retreating process of the striking means or the vibrating section. Is stopped, and when the striking means or the vibrating section is turned to the pre-vibration advance again, a step-like cutting edge locus for performing the cutting by recolliding with the milling tool or the holder holding the same is generated and cut off. It is characterized by cutting.

In order to achieve the fourth object, the present invention provides a milling tool held movably only in the feed direction or a holder holding the same, and a tool or a holder holding the tool. It is characterized in that it comprises a striking means or a vibrating section arranged behind the feed direction with a clearance of both amplitudes or more, and a means for applying vibration to the striking means or the vibrating section.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 3A, 3B, 3C, 3D and 3E schematically show the mechanism of the step vibration cutting method according to the present invention. In FIG. 3, 1 is a tool, 2 is a cutting blade attached to the tip of the tool, and 3 is a workpiece. The tool 1 is a holder 1a
, And the holder 1a can freely move over a distance of both amplitudes 2A or more in the cutting direction via the guide means 1b. The workpiece 3 is moved relative to the tool 1 at a cutting speed Vw as shown by an arrow, and the cutting edge 2 cuts by coming into contact with the surface of the workpiece 3 to discharge chips lt. It is supposed to.

As shown in FIG. 3 (a), the present invention is connected to the output side of the vibration generating means 5 or transmitted to the rear of the tool 1 (in this example, the holder 1a), particularly in the cutting direction. A striking means or vibrating section 4 (hereinafter referred to as a striking means unless otherwise specified) is provided. The striking means 4 is not connected or coupled to the holder 1a of the tool 1, and in the initial state, the tip 4 of the striking means 4
0 is a hit portion of the tool 1 (an end face of the holder in this example) 10
It is made to confront 0 with a clearance C of both amplitudes 2A or more.

At the time of cutting, the vibration generating means 5 is driven to vibrate the striking means 4 in the cutting direction, whereby the holder 1a is impacted in the course of each vibration before the tool 1 integrated therewith. The cutter 1 is moved forward and cut by the cutting blade 2, and in a retreat stroke of each vibration, the tool 1 is moved along with the workpiece 3 to stop cutting. The cutting conditions at this time are as follows: When F is the frequency and A is the amplitude (single amplitude),
The cutting speed Vw needs to satisfy 2πAF> Vw. When 2πAF ≦ Vw, a pulse-like waveform, which is a feature of the present invention, cannot be created. The frequency is not particularly limited. In general, low frequency vibration of 1 to 2000 Hz or ultrasonic vibration of 10 to 500 KHz is used, although it depends on the type of the cutting method to be processed and the material of the workpiece.

FIG. 3B shows a forward process (cutting process) in one vibration cycle. When the tool 1 is retracted with the cutting edge 2 in contact with the workpiece 3, the vibration from the vibration generating means 5 is output. Since the striking means 4 advances and strikes the holder 1a in the cutting direction so that the clearance C is lost by the advance output, the holder 1a advances through the guide means 1b. (= 2πAF), the cutting edge 2 cuts the workpiece 3, and chips lt are generated. The vibration generating means 5 may be of any type, such as a mechanical type, a type utilizing a fluid pressure represented by a hydraulic cylinder, or a combination thereof, as will be described later. In this example, a rotating wheel having a crank is used. Assuming that the rotational angular velocity of the wheel is ω (2πF), the tool speed Vmax is Aω (= 2πAF). The cutting length of the chip lt for each cycle of the vibration amplitude is Vw / F.

Next, in the return stroke in one vibration cycle, the output of the vibration generating means 5 changes in the backward direction.
As shown in (c), the striking means 4 is separated from the holder 1a,
It confronts the hit surface 100 with the clearance C described above. Since the cutting edge 2 is in contact with the cutting point 30 of the workpiece 3, the tool 1 and the holder 1 a are retracted together with the workpiece 3 at a speed Vw of the tool 1 which is no longer subjected to the impact force. This period is a pause period during which cutting is not performed. That is, in the present invention, the cutting blade 2 is made to function not as an active cutting blade as in the vibration cutting method but as a passive cutting blade.

Then, in the next vibration cycle, when the output of the vibration generating means 5 changes to the forward side again and the clearance C between the striking means 4 and the holder 1a decreases, as shown in FIG. Of the cutting blade 2 starts cutting again. And FIG.
As shown in (e), the cutting is performed by the forward movement of the tool 1 in the subsequent impact stroke, and the next chip lt ₂ is generated. Hereinafter, step-like cutting without the return stroke of the tool 1 is performed by repeating FIGS. 3B to 3E.

FIG. 4 shows the displacement-time relationship of the cutting edge according to the present invention, wherein the edge draws a step-like trajectory.
At the time of tool advance indicated by a thick line by the impact means, cutting is performed by the same mechanism as the vibration cutting method, and the impact means is retracted (returned).
At times, the tool 1 does not retreat as in the case of vibration cutting, and the cutting edge of the tool is in a rest period in contact with the cutting point. With such a step cutting mechanism, a pulse cutting force waveform similar to that of the vibration cutting method can be obtained, so that the apparent rigidity effect and the processing accuracy improvement effect of the vibration cutting method can be obtained as they are. Moreover, since there is no relative speed between the cutting edge and the workpiece when cutting is stopped, unnecessary rubbing of the cutting edge does not occur, and harmful impact force from the workpiece 3 to the tool 1 does not directly act on the cutting edge. The load is reduced. Therefore, chipping hardly occurs, and the tool life can be improved as compared with the vibration cutting method.

FIGS. 5 and 6 show a first embodiment of a cutting method and apparatus in which the present invention is applied to a milling-type cutting process.
In the first mode, step vibration cutting is performed by imparting not a translational vibration but a circumferential vibration to a milling tool, that is, a tool having a cutting edge capable of cutting in the tool circumferential direction. Is the feature. 5 and 6 show a tapping as an example. The tapping is a machining method that is frequently used and has a large cutting resistance because it is a full-form tool, and is a machining method that easily causes troubles such as tool breakage. Reference numeral 1 denotes a cylindrical or cylindrical milling tool (in this example, a tap), which has a cutting edge 2 on the distal end peripheral surface and has a shank 1c in the axial direction. A tongue portion 10 having a reduced width serving as a hit portion is provided. 3 is a workpiece,
Although not shown, it is attached to a rotating main shaft or the like, and is rotated at a predetermined rotation speed N.

Reference numeral 1a denotes a step vibration holder, which is connected and integrated with a circumferential vibration main shaft 5 'as an output portion of the vibration generating means 5, and vibrates in a circumferential direction at a constant period integrally therewith. It has become. Circumferential oscillation main shaft 5 '
Is attached to the tool post using, for example, an NC lathe, thereby providing a predetermined feed f. In this example, the vibration generating means 5 is of a type that converts the rotation of the motor into vibration in the circumferential direction. That is, an eccentric angular axis 521 is provided at the lower end of the first axis 520 that receives the transmission of the rotational force from the rotary actuator, and this angular axis 521 is attached to the first axis 520.
A circumferential vibration is generated by fitting a bifurcated portion 523 of a lever 522 having a base end fixed to a circumferential vibration main shaft 5 ′ parallel to the main shaft 5 ′.

The holder 1a has a striking means 4 near the end. In this example, the striking means 4 is configured by providing a pair of notches 101, 101 in the holder 1a, and fixing the plate-like members 4a, 4a to the pair of notches 101, 101 in an opposed manner by screws or the like. And
A clearance C of both amplitudes 2A or more is provided between the plate-shaped members 4a, 4a and both surfaces 100, which are to be hit portions of the tongue portion 10, and the milling tool 1 is free in the circumferential direction up to the clearance C. You can move to. Naturally, it may be formed integrally with the holder without using a plate-shaped member.

FIG. 7 shows the principle of stepping screw tapping by such a device. When the circumferential oscillation main shaft 5 'rotates in the cutting direction indicated by the arrow (a), the holder 1a is rotated.
It moves with. For this reason, in the forward rotation process in one vibration cycle, the clearance C between the both surfaces 100, 100 of the tongue portion 10 and the plate-shaped members 4a, 4a is lost, and as shown in FIGS. Meanwhile, both surfaces 100, 100 of the tongue portion 10 move in the cutting direction (forward direction) due to collision with the plate-shaped members 4a, 4a. Therefore, the tongue portion 1
The cutting blade 2 connected to 0 performs cutting. The workpiece is rotating relative to the milling tool.

Next, when the vibration main shaft 5 'moves in the reverse direction in one vibration cycle, only the holder 1a moves in the reverse direction (negative direction) while the milling tool 1 is kept at the cutting point due to the clearance C. It moves, during which the milling tool 1 is returned along with the workpiece 3. Therefore, the cutting edge 2
No cutting is performed, and a pause period is set. (C) (d)
Indicates the end of this pause period.

Thereafter, when the next oscillation cycle starts and the oscillation main shaft 5 'turns again in the cutting direction, the both surfaces 1 of the tongue portion 10 are moved.
00, 100 collide with the plate-shaped members 4a, 4a, and from there, the holder 1a moves in the cutting direction with the rolling tool 1, so that the cutting is performed again as shown in (e) and (f), and
When the vibration main shaft 5 ′ rotates in the opposite direction, the milling tool 1 rotates together with the workpiece 3 as shown in (g) and (h), and the holder 1
Only a moves in the reverse direction to suspend cutting. By repeating such operations, step vibration cutting is performed in the circumferential direction. The operation of this method is the same as that of the above-described plane cutting. The vibration generating means 5 may be any type as described later.

In drilling and tapping, there is a cutting method using a step feed. However, this method merely intermittently feeds chips for the purpose of cutting off chips in order to improve chip dischargeability. Therefore, although the cutting force becomes intermittent, the maximum value of the cutting force becomes the same as that of the conventional cutting method, and does not become the pulse cutting force. It is definitely different in that it cannot be obtained. That is, according to the method of the present invention, since the impact cutting force (pulse cutting force) is applied by hitting the tool 1 and the cutting is completed within the transient response of the workpiece, the maximum value of the cutting resistance itself becomes low. A great effect of improving machinability can be obtained.

FIG. 8 shows a first example in which the present invention is applied to a non-rolling type cutting process, that is, a planing method and an apparatus, which are typical examples of the translational cutting. While the workpiece 3 is attached to the head 6, a guide means 1b is provided on a tool rest 7a on a table 7 facing the head 6, and the tool 1 held by the holder 1a is freely moved only in the cutting direction by the guide means 1b. Mounted as possible. A vibration generating means 5 having a striking means 4 is installed on the table 7 near the tool rest 7a. In this example, a vibration table 52 is attached to a table 7 via an abutment, and a motor 53 and a crank mechanism 54 for converting this rotation into reciprocating motion are provided on the same or another abutment.
Are connected to the vibration table 52.

The holder 1 is placed on the vibration table 52.
The block-shaped or rod-shaped striking means 4 facing the struck portion 100a is fixed so as to be adjustable in position with screws 4d so as to have a clearance C of both amplitudes 2A or more.

FIG. 9 shows a second embodiment in which the present invention is applied to a planing method and apparatus. The work 3 is mounted on a table 7 and moved in the cutting direction, while the head 6 is moved to the table 6 side. The holder 1a to which the tool 1 is attached is attached by the guide means 1b such that the holder 1a can be freely moved in the cutting direction over a distance of both amplitudes 2A or more. In this embodiment, a motor 53 and a slider-type crank mechanism 54 are used as the vibration generating means 5 having the striking means 4. That is, the crank 54 having the vibrating portion 40 at the tip and functioning as the striking means 4
a is pivotally supported by an abutment provided on the head 6 and a slider 54 which converts the rotation of the motor 53 into a linear reciprocating motion.
b is disposed in a window hole in the middle of the crank 54a, and a clearance C of both amplitudes 2A or more is set between the vibrating part 40 and the vibrated part 100 as a side end of the holder 1a. .

According to this apparatus, at the time of cutting, the holder 1
When the tip of the crank 54a collides with the vibrator 40a, the cutting edge of the tool is cut by applying a pulse cutting force, and when the tip of the crank 54a moves in the return direction in one oscillation cycle, the tool A cycle is repeated in which the cutting edge is retracted together with the workpiece 3 in a state of contact with the workpiece 3 (at the time of non-cutting) and collides again with the tip of the crank 54a directed in the forward direction.

FIG. 10 shows an example in which the present invention is applied to a turning method and apparatus which are other typical examples of non-rolling type cutting (translational direction cutting). The workpiece 3 is mounted on a main shaft and rotated at a speed Vw, and a mechanism similar to the planing apparatus shown in FIG. 9 is provided on the table side. In order to avoid repetition of the description, the same portions are denoted by the same reference numerals, and the description is omitted. The operation is the same as that of the above-mentioned planing apparatus except that the workpiece 3 rotates instead of translate, and thus the description thereof is omitted.

FIGS. 11 to 13 show examples in which the present invention is applied to a machining method and an apparatus of a milling type and step vibration is generated in a cutting direction (circumferential direction). 11 shows an example of tapping to which the present invention is applied, FIG. 12 shows an example of drilling to which the present invention is applied, and FIG.
3 shows an example of an end mill to which the present invention is applied. Application to these can be performed by generating the above-described step vibration in the tool rotation direction. That is, the present invention can be realized by providing a special step vibration cutting mechanism on a spindle which applies rotation and rotational vibration to a milling tool or a holder holding the milling tool.

The vibration generating means 5 provided on a head such as a machining center is optional, but a preferable example is a pulse motor. Such pulse motors are
Compared with the mechanical vibration generation method, it has an advantage that the apparatus is compact and an advantage that the degree of freedom of frequency adjustment is increased. The main shaft housing 56 of the vibration generating means 5 (in this example, a pulse motor) has a built-in guide means 1b through which a step vibration holder 1a is fitted. On the other hand, the main shaft housing 56 has a vibration / rotation main shaft 5 ′ extending as an output unit. The vibration / rotation main shaft 5 'rotates while vibrating in the circumferential direction. The holder 1a has a tongue portion 1 having parallel surfaces 100, 100 at 180 degrees symmetrical positions at the upper end portion as in FIG.
0 'is provided on the vibration / rotation main shaft 5'.
As in the case of (1), a hitting means (hitting member) 4 'having a parallel surface acting as a vibrating portion is fitted at a 180-degree symmetrical position, and the parallel surface of the hitting means 4' and the parallel surface of the tongue portion 10 'are fitted. A clearance C having both amplitudes of 2A or more is provided between 100 and 100. In this example, the holder 1a and the striking means 4 '
In this point, a clearance is provided between the shank of the milling tool 1 and the holder which also serves as a striking means as shown in FIG. The milling tool 1 is fastened and fixed to the holder 1a by a collet chuck.

In this case, the pulse motor as the vibration generating means 5 is operated by giving an instruction to rotate while vibrating (forward-backward in the rotational direction) with a ratio of forward rotation: reverse rotation of 2: 1 by the controller. To do. As in the known apparatus, in FIGS. 11 and 12, a linear feed f in the direction approaching the workpiece is given to the milling tool 1 by moving the tool rest. In FIG.
It moves in the Y and Z directions to provide feed in each direction. The workpiece 3 is fixed so as not to rotate. The step vibration cutting operation shown in FIGS. 11 to 13 is the same as that of FIG. 7 described above, and will be briefly described. In the stroke in which the vibration / rotation main shaft 5 ′ moves in the cutting direction in the vibration cycle, the striking means 4 is used. 'And tongue part 1
Since the clearance C between 0 ′ is lost and the striking means 4 ′ collides with the tongue 10 ′, the vibration / rotation main shaft 5 ′ moves with the holder 1a for step vibration, and the rolling tool integrated with the holder 1a. 1 performs cutting. Next, in the stroke in which the vibration / rotation main shaft 5 'moves in the reverse direction in the vibration cycle, the vibration / rotation main shaft 5' and the striking means 4 remain with the step vibration holder 1a in that position due to the clearance C. Only 'reverse. During this time, cutting is stopped. Thereafter, the vibration / rotation main shaft 5 'rotates again in the cutting direction, and the striking means 4' collides with the tongue portion 10 'of the step vibration holder 1a, and from there, rotates with the step vibration holder 1a. The operation of cutting with the milling tool 1 is repeated again.

FIG. 14 and FIG. 15 show that the present invention is applied to the rolling process by a rolling tool represented by a drill, an end mill, a reamer, etc., and that a step vibration is generated in a feed direction instead of a cutting direction. An example of such a processing method and apparatus is shown. The embodiment of FIG. 14 is suitable for a case where the rolling tool 1 has both a rotary cutting edge (outer peripheral blade) and an axial cutting edge (chisel edge or bottom blade). FIG.
4 (a) shows a mode in which the rolling tool rotates and the workpiece does not rotate, and FIG. 4 (b) shows a mode in which the workpiece rotates without the rotating tool. In FIG. 14A, the workpiece 3 is fixed to the table 7 by an appropriate means. On the other hand, a rotating spindle 5 ′ is rotatably supported by a bearing 500 on a spindle housing 56 provided on a tool rest such as a machining center or a drilling machine.
The rotating main shaft 5 ′ has a cylindrical shape, and in a tip region in the cylinder,
A guide means 1b such as a slide guide or a ball guide is fitted inside, and a holder 1a for a step vibration having a shaft portion is attached to the guide means 1b so as to be relatively non-rotatable and movable in a feed direction (axial direction). The milling tool 1 is fastened and fixed to the holder 1a by a collet chuck. A vibration generating means 5 is provided on a rotating main shaft 5 ′ axially rearward of the holder 1 a. The vibration generating means 5 is optional, such as a crank mechanism. In this example, a hydraulic cylinder is used.
It is fixedly fitted inside the cylindrical portion of the rotating main shaft 5 '. The striking means 4h is a cylinder piston (piston rod) in this example.
The piston 4h extends into the guide means 1b, and its front end is provided with a clearance C of both amplitudes 2A or more, and is opposed to the struck portion 100 which is the rear end of the holder 1a.

In FIG. 14B, the workpiece 3 is NC
It is attached to a main shaft 8 such as a lathe by a chuck or the like, and is rotated at a predetermined rotation speed. On the other hand, a guide means 1b such as a slide guide or a ball guide is internally fitted in a tip region of a casing 5 "fixed to a tailstock such as an NC lathe or a turret tool rest, and a shaft portion is fitted thereto. Is mounted so as to be relatively non-rotatable and movable in the feed direction (axial direction).
The milling tool 1 is fastened and fixed to the holder 1a by a collet chuck. A vibration generating means 5 is provided in a casing 5 "axially rearward of the holder 1a. The vibration generating means 5 is optional such as a crank mechanism. In this example, a hydraulic cylinder is used. It is fixedly fitted inside the 5 "cylindrical portion. Hitting means 4h
Is a cylinder piston (piston rod) in this example. The piston 4h extends into the guide means 1b, and has a clearance C at both ends of which is equal to or more than 2A in amplitude, and is a struck portion 100 which is a rear end of the holder 1a. Is facing.

In each of FIGS. 14A and 14B,
The holder 1a is not rotatable relative to the guide means 1b, and is held so as not to fall out of the guide means 1b. FIGS. 15A, 15B, and 15C illustrate a structure for that purpose. In FIG. 15A, the guide unit 1b is connected to the striking unit 4h.
1b ₁ that guides the shaft and the shaft 1a ′ of the holder 1a.
Incorporating in series like them is divided into a second portion member 1b ₂ to guide by a spacer ring 1b ₃ a.
Then, attach the retaining ring 1c is in the vicinity of the end portion of the shaft portion 1a ', and so as to achieve a retained by abut the該止Me ring 1c on the end face of the second part body 1b _2, also, the shaft portion 1
The outer periphery of a 'is aimed detent by fitting the spline groove 111 to form a spline 110, to form it on the inner periphery of the second part body 1b ₂ as shown in FIG. (b). Figure 15 (c), the longitudinal grooves 112 formed in the vicinity of the end portion of the shaft portion 1a ', the second part body 1b ₂ wherein the longitudinal groove 112
Is inserted at right angles to the axis to prevent the holder 1a from coming off and from rotating. The length i.e. movable pin center distance C ₁ pin 1d longitudinal groove 112 is required to be larger than the clearance C. Note that FIG. 15 is merely an example, and the present invention is not limited to the illustrated structure.

In FIG. 14 (a), the turning spindle 5 'is rotated by a separate power source such as a motor and a transmission means so as to obtain a required cutting speed V, and the vibration generating means 5 performs the rolling. While the striking means 4h (in this example, a piston rod) is reciprocated, the main shaft housing 56 containing the rotary main shaft 5 'is moved in the axial direction to obtain the feed at the feed speed fw. This feed speed fw is fw <2πA
F (A: amplitude, F: frequency). As a result, the holder 1a holding the milling tool 1 is periodically driven in the feed direction by the striking means 4h to perform a step vibration cutting in which cutting is performed only at the time of hitting and paused at the time of non-hitting is repeated.
That is, in the extension (advance) stroke of the piston as the striking means 4h in one oscillation cycle, the clearance C is lost and the struck portion 100 at the rear end of the holder is struck. In the retraction (return) stroke of the piston, the milling tool 1 does not retreat only because the clearance C is recovered, and the tool remains in contact with the cutting point and cutting is stopped. And, again, the extension (forward) of the piston
By moving to the stroke, the struck portion 100 at the rear end of the holder
Is hit again and cutting is performed. fs is a feed for each vibration. In FIG. 14B, the workpiece 3 is rotated by the main shaft 8, and in this state, the housing 5 ″ is moved in the axial direction while the striking means 4h (in this example, a piston rod) is reciprocated by the vibration generating means 5. Go to
fw <2πAF (A: amplitude, F: frequency) is given. Thereby, the holder 1a holding the milling tool 1 is periodically driven in the feed direction by the hitting means 4h, and is driven.
By the same mechanism as in the above 14 (a), step vibration cutting in which cutting is performed only at the time of hitting and pause at the time of non-hitting is repeated is performed.

FIG. 16 shows an example in which the present invention is applied to a broaching method and apparatus as another example of non-rolling. In this example, a tip 1e of a broach as a tool 1 is supported by a lower guide 1f having an elastic body 1j, and
The rear end 1g having a zero is inserted into the guide means 1b so as to be movable in the cutting direction. In this example, a hydraulic cylinder is used as the vibration generating means 5, and the hitting portion 100 at the rear end 1g of the tool is opposed to the hydraulic cylinder piston 4h as a hitting means with a clearance C of both amplitudes 2A or more. I have. In this device, the hydraulic cylinder 5 reciprocates and oscillates the piston to periodically apply a forward and backward stroke. In this way, in the extension (forward) stroke of the piston 4h in one vibration cycle, the tool 1 is cut to strike the tool rear end 1g and push it into the lower guide 1f against the bias of the elastic body 1j. , Clearance C
The tool 1 does not retreat in the retreat (return) stroke of the piston 4h unlike the vibration cutting, so that the cutting edge is in a rest period while being in contact with the cutting point. Such an operation mechanism enables step vibration broaching.

The above description has described only some embodiments of the method and apparatus of the present invention, and the present invention is not limited thereto. 1) The impact is not only applied to the holder 1a but also to the tool 1
May be added directly. 2) The guide means 1b for moving the tool 1 in the cutting direction or the feed direction is not limited to a ball type, a metal type and other linear guides.
Static pressure guide, hydraulic guide, slide bearing,
A system such as elastic support by a leaf spring may be used. 3) The vibration generating means 5 is not limited to a mechanical type such as a motor and an eccentric disk-crank mechanism, a motor and a slider-crank mechanism, and a link mechanism.
Further, any other means such as electrostrictive means such as a piezo element or an ultrasonic vibrator, or driving by an electromagnet may be used. 4) In the case of machining with a milling tool, the relationship between the tool 1 and the workpiece 3 is not limited to the tool vibration-workpiece rotation method as shown in FIG. Rotation may be performed, and furthermore, tool rotation-workpiece vibration, workpiece rotation and vibration may be performed.

[0041]

Next, examples of the present invention will be described. [Example 1] Step vibration planing was performed using the method and apparatus of the present invention. The apparatus shown in FIG. 8 is used as the apparatus, and the workpieces are aluminum (A2017), carbon steel S45C, Ni-based alloy (trade name: Inconel 718),
Pre-hardened steel (40HRC), hardened steel SK3 (60
HRC) and β titanium alloy were used. Carbide K10 was used as the cutting blade of the cutting tool, and the cutting tool was mounted on a linear guide provided on a milling table so that it could be freely moved only in the cutting direction. Behind the cutting tool, a rod-shaped striking tool is fixed as a striking means on a vibration table, and the rotation of the motor is converted into reciprocating motion by a crank mechanism to generate vibration in the vibration table, and the cutting tool is used to strike the cutting tool. I hit it. The clearance C between the tip of the impact tool and the rear end of the holder was set to 0.5 mm. The vibration conditions at this time were a vibration frequency of 50 Hz and both amplitudes of 0.4 mm, and the cutting conditions were a cutting depth of 0.1 mm and a cutting speed of 1.2 m / mi.
n.

For comparison, a conventional cutting method without vibration and a vibration cutting method were also performed. The vibration cutting method was performed by fixing a tool directly to the vibration table. Cutting conditions,
The vibration conditions were the same as above. FIG. 17 shows the results of cutting by the above three methods and measuring the cutting resistance.
As is clear from these results, the step vibration cutting method of the present invention has a cutting resistance of about 1/3 to 1/5 as compared with the conventional cutting method.
, Which is slightly higher than the vibration cutting method. However, it can be seen that the hardness of the hardened steel is lower than that of the vibration cutting method.

Further, as a result of measuring the cross-sectional curve in the cutting direction, a good mirror surface was obtained on the cut surface according to the method of the present invention without forming any cutting edge on the tool. And in the case of vibration cutting as well as vibration cycle per L _T (= Vw / F) cutting marks for each was observed. Next, the Ni-based alloy was cut by a dry method with a cutting distance of 830 mm by the above-mentioned three methods, and the cutting edge damage state (rake face) was examined. The results are shown in FIGS. 18 (a), (b) and (c). (A) is a conventional method, in which significant flank wear occurs. (B) shows the case of the vibration cutting method, in which chipping of 0.7 to 0.8 mm width occurred from the middle of the rake face. On the other hand, in the method of the present invention (c), chipping and flank wear did not occur at all. In addition, after cutting 30 workpieces, the flank wear state was observed. In the case of vibration cutting, the flank wear increased, whereas several micro chippings occurred on the cutting edge, In the case of step vibration cutting, a result was obtained in which flank wear chipping did not occur.

Example 2 Tapping was performed according to the present invention. As a device, a step vibration drive device was mounted on a tool post of an NC lathe as shown in FIG. 5, a workpiece was mounted on a spindle and rotated, and a feed was given to the tool post to perform tapping. As the step vibration generating device, a device that converts the rotation of the motor into a vibrating motion is used. A dedicated holder is attached to the circumferential vibration main shaft, and 0.1 mm is provided between the tongue portion of the tap and the plate member of the holder. A 6 mm clearance is provided so that the tap can move in the circumferential direction up to the clearance.

The frequency of the holder is 50 Hz, and the amplitude A is 0.
3 mm, tool rotation speed: 26 rpm, cutting method 1-stroke thread cutting, cutting oil JIS W1 class water-soluble is used, and the tap is a straight tap for pipes, that is, PF1
/ 4-SKH-homo treatment was used. As a work,
SUS304, thickness 20 mm, prepared hole 11 mm was used. For comparison, a conventional tapping method and a vibration tapping method were performed. The vibration tapping method was performed by attaching a tap to the vibration main shaft via a normal holder.

First, the result of measuring the tapping torque is shown in FIG. It can be seen that the method of the present invention is comparable to the vibration tapping method and is reduced to about 2/3 of the conventional tapping method. Next, when the surface processing accuracy was observed, the method of the present invention had gloss similar to that of the vibration tapping method and had a better surface than the conventional tapping method. Observation with a CCD camera (magnification: 5 times) shows that on the thread flank surface by the vibration tapping method, cutting marks for each period of vibration are observed approximately every calculated value L _T (= v / F) = 0.2 mm. Was. In the case of the step vibration tapping according to the present invention, the same cutting mark as that of the vibration tapping was observed, but it was thinner than that obtained by the vibration tapping. This is considered to be due to the fact that the cutting edge does not separate from the cutting point.

The shape precision was measured by screwing a thread gauge (JIS, Class A) to the machined screw and measuring the clearance between the thread gauge and the thread. The results show that the method of the present invention has a clearance of 80 μm equivalent to the vibration tapping method, and the clearance of the conventional tapping method is 11 μm.
It was found to be better than 0 μm. Screw depth 2
The abrasion state of the tap edge after ten tappings were performed at 0 mm was examined. The results are schematically shown in FIGS. In these figures, (a) is a flank and (b) is a rake face.
FIG. 23 shows the relationship between the flank and the rake face.

Regarding the flank, in the case of the conventional tapping method (FIG. 20), dripping is observed at the tip, and in the case of the vibration tapping method (FIG. 21), the wear is most severe. On the other hand, in the method of the present invention (FIG. 22), the degree of wear is very small, and the cutting edge is maintained in a sharp state. On the rake face, in the case of the conventional tapping method, adhesion of the work material occurs, and in the case of the vibration tapping method, minute chipping occurs. On the other hand, in the case of the method of the present invention, neither chipping nor adhesion occurred, and it was found that good wear prevention and chipping prevention effects were obtained, and the tap life could be improved.

[Embodiment 3] Step vibration drilling was performed by applying the present invention. An apparatus of the type shown in FIG. 14A was used. A hydraulic cylinder is used as the vibration generating means, the frequency F: 50 Hz, the amplitude A: 0.
An axial vibration of 1 mm was generated. A JIS standard type straight drill with a diameter of 3 mm and a tool length of 47 mm was used as the tool, which was fixed to the holder, and a clearance of 0.6 mm was provided between the axial rear end face of the holder and the tip of the piston rod of the hydraulic cylinder. The holder can be moved in the feed direction with the clearance as a limit. The workpiece used was a β titanium alloy (solution-treated material of Ti-15V-3Cr-3Sn-3Al) which is an extremely difficult-to-cut material. The processing conditions are as follows: Cutting speed V: 6.6 m /
min, feed speed fw: 0.03 mm / rev, hole depth: 15 mm. The cutting oil used was a water-insoluble cutting oil.

FIG. 24 shows the hole diameter accuracy obtained by drilling under these conditions in comparison with a conventional drilling method that does not give vibration. From FIG. 24, it can be seen that when step vibration drilling is performed by applying the present invention, the hole diameter enlargement ratio is small, and hole drilling with high accuracy closer to the used drill diameter is performed. Next, FIG. 25 shows the result of measuring the burr height on the exit side of the hole formed by the above two types of processing methods. A feature of the β titanium alloy is that burrs are very easily generated at the time of drilling. However, in the case of the present invention, it is possible to significantly reduce the burr, and it can be seen that workability is also good in this aspect.

[Embodiment 4] The present invention was applied to drill an inclined hole. The slant hole drilling is a small-diameter slant hole drilling having a diameter of about 1 mm or less used for, for example, a pilot hole of an injector part, and is one of difficult processing forms. An apparatus of the type shown in FIG. 14A was used. A hydraulic cylinder was used as the vibration generating means, and an axial vibration having a frequency F: 50 Hz and an amplitude A: 0.1 mm was generated. 1m in diameter as a tool
A JIS standard type straight drill having a tool length of 20 mm and a tool length of 20 mm was used, and was fixed to the holder.
The holder was allowed to move in the feed direction with the clearance as a limit. The workpiece used was SCM435. The processing conditions were as follows: cutting speed V: 7.9 m / min, feed speed fw: 0.00
86 mm / rev, hole depth: 10 mm, hole inclination angle 0 to 2
0 °. The cutting oil used was a water-insoluble cutting oil.

FIG. 26 shows the results of machining under these conditions in comparison with the conventional drilling method that does not apply vibration and the axial vibration drilling method. As is clear from FIG.
The hole position accuracy is almost as good as the axial vibration drilling method. This is because the drill biting property at the time of processing the oblique hole is improved. In addition, as a result of observing the state of the tip of the drill, it was found that in the axial vibration drilling, chipping was likely to occur on the cutting edge near the drill chisel, but in the step vibration processing of the present invention, the cutting edge was not chipped. This is because in the axial vibration drilling, biting and detachment are repeated, while in step vibration machining, biting and stopping are repeated, and there is no detachment process.

[0053]

According to the first aspect of the present invention described above, the striking means is vibrated in a state in which the tool or the holder for holding the striking means is positioned with a clearance larger than the amplitude of both vibrations in the cutting direction. The cutting is performed while maintaining the state where the cutting edge is in contact with the cutting point with each vibration (vibration without return stroke). In addition to performing precision cutting, harmful impact force does not directly act on the cutting edge, so the load on the cutting edge is reduced, preventing chipping of the tool cutting edge in machining hard materials and difficult-to-cut materials. An excellent effect that a long life can be ensured can be obtained. According to the second aspect, an excellent effect that the effect of the first aspect can be realized with a simple structure is obtained.

According to the third aspect, in rotary cutting using a rolling tool, good precision cutting can be performed similarly to the vibration cutting method, and harmful impact force does not directly act on the cutting edge. As a result, the load on the cutting edge is reduced, and the excellent effect of preventing wear and chipping of the tool cutting edge and ensuring a long service life in tapping, drilling, and end milling of hard or difficult-to-cut materials is obtained. Can be According to the fourth and fifth aspects, an excellent effect that the feature of the third aspect can be realized with a simple structure is obtained.

According to the sixth and seventh aspects, in the rotary cutting using the milling tool, the vibration generating device is vibrated in the feed direction in the presence of a clearance having both amplitudes or more, and the milling tool or the milling tool is vibrated. By hitting the holder that holds the workpiece, step vibration cutting is performed only when hitting and paused when not hitting, so that the rotary cutting edge (outer peripheral cutting edge) such as a drill or end mill and the axial cutting edge (chisel edge or When using a milling tool that has both a bottom edge and a bottom edge, it is possible to achieve good precision cutting, such as reduction of burrs and improvement of shape accuracy, especially for the axial cutting edge. Since the force does not act directly on the cutting edge, the load on the cutting edge is reduced, and difficult processing such as drilling and finishing of high-hardness materials and difficult-to-cut materials, or processing of small diameter deep holes and oblique holes In form Excellent effect that the wear and chipping of the cutting edge can be secured to a high tool life prevention can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing the principle of a vibration cutting method.

FIG. 2 is a diagram showing a cutting displacement curve in the vibration cutting method.

FIGS. 3A and 3B are explanatory diagrams schematically showing a cutting state when the step vibration cutting method according to the present invention is applied to translational cutting, wherein FIG. 3A is an initial state, FIG. 3B is a cutting stroke, and FIG. The rest step, (d) shows the cutting start step, and (e) shows the cutting step.

FIG. 4 is a diagram showing a relationship between cutting edge displacement and time in the step vibration cutting method according to the present invention.

FIG. 5 is a cross-sectional view showing an example of an apparatus when the step vibration cutting method according to the present invention is applied to circumferential cutting.

FIG. 6 is a sectional view taken along line XX of FIG. 5;

7A and 7B are explanatory views schematically showing a cutting mechanism when the step vibration cutting method according to the present invention is applied to circumferential cutting, and FIG. 7A is a sectional view taken along the line YY-Y of FIG.
FIG. 5B also shows a cross section taken along the line XX of FIG. 5 at that time. (C) shows a section taken along the line YYY in FIG.
(D) also shows a cross section of FIG. 5XX at that time. FIG. 5E shows a cutting process in the next vibration cycle.
FIG. 5F also shows a section taken along the line X-X in FIG. (G) shows a section taken along the line YY in FIG. 5 in a resting stroke in the next oscillation cycle, and (h) shows a section taken along the line 5XX in FIG.

FIG. 8 is a side view showing an example in which the present invention is applied to a planing step vibration cutting device.

FIG. 9 is a side view showing another example in which the present invention is applied to a stepping vibration cutting device for planing.

FIG. 10 is a side view showing an example in which the present invention is applied to a step vibration cutting device for turning.

FIG. 11 is a cross-sectional view illustrating an example in which the present invention is applied to a stepping vibration cutting device for tapping.

FIG. 12 is a side view showing an example in which the present invention is applied to a step vibration cutting device for drilling.

FIG. 13 is a side view showing an example in which the present invention is applied to a step vibration cutting device for end milling.

14A is a cross-sectional view showing an example in which the present invention is applied to a cutting device for tool rotation and non-rotation of a workpiece, and FIG. 14B is a cross-sectional view of the same for non-rotation of tool and rotation of a workpiece. It is sectional drawing which shows an example applied to the apparatus.

FIG. 15A is a partial cross-sectional view showing an example of a mechanism for preventing rotation of a holder and a retaining mechanism in the apparatus of FIG. 14;
FIG. 1B is a cross-sectional view taken along the line Z-Z in FIG. 1A, and FIG.
FIG. 13 is a partial cross-sectional view showing another example of a mechanism for preventing rotation and removal of the holder in the device of No. 4;

FIG. 16 is a side view showing an example in which the present invention is applied to a step vibration cutting device for broaching.

FIG. 17 is a diagram showing measurement results of cutting resistance when the present invention and a conventional cutting method and a vibration cutting method are applied to planing.

FIG. 18 is an enlarged sectional view showing a tool rake face damage state of the present invention, a conventional cutting method and a vibration cutting method, wherein (a) is a case of a conventional cutting method, (b) is a case of a vibration cutting method, and (c) ) Shows the case of the method of the present invention.

FIG. 19 is a diagram showing a relationship between a cutting torque and a tap feed amount when the present invention and a conventional cutting method and a vibration cutting method are applied to tapping.

FIG. 20 (a) is an enlarged cross-sectional view showing a state of a flank of a tip blade when a conventional cutting method is applied to tapping;
(B) is an enlarged sectional view showing the state of the rake face of the tap end edge when the conventional cutting method is applied to tapping.

FIG. 21 (a) is an enlarged cross-sectional view showing a state of a flank surface of a tap end edge when a vibration cutting method is applied to tapping;
(B) is an enlarged sectional view showing the state of the salvage surface of the tip blade when the vibration cutting method is applied to tapping.

FIG. 22 (a) is an enlarged cross-sectional view showing a state of a flank surface of a tap end edge when the method of the present invention is applied to a tapping stand.
(B) is an enlarged sectional view showing a state of a salvage surface of a tap tip blade when the method of the present invention is applied to a tap stand.

FIG. 23 is an explanatory view showing a flank and a rake face of a tap whose wear state is to be observed in the example.

FIG. 24 is a diagram showing the relationship between the number of drilled holes and the drilled hole diameter in an example in which the present invention is applied to drilling, in comparison with the case of conventional drilling.

FIG. 25 is a diagram showing a relationship between the number of processing holes and the height of an outlet burr in an example in which the present invention is applied to drilling, in comparison with the case of conventional drilling.

FIG. 26 is a diagram showing a relationship between a hole inclination angle and a positional accuracy in an embodiment in which the present invention is applied to inclined hole processing, in comparison with a conventional method and an axial vibration method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tool 1a Holder 2 Cutting blade 3 Workpiece 4 Hitting means or vibrating part 5 Vibration generating means 5 'Rotating main shaft 5 "Casing 10 Tongue part C Clearance A Amplitude (single amplitude) 2A Both amplitudes

Claims (7)

[Claims] 1. A striking means or a vibrating section is provided behind a tool or a holder for holding the same with a clearance equal to or greater than both amplitudes, and the striking means or the vibrating section is vibrated in a cutting direction. When the cutting speed Vw is Vw <2πAF (A:
Amplitude or F: frequency), the tool or the holder holding the tool is periodically hit and driven in the cutting direction, and the cutting is performed only during the pre-vibration step where the clearance is lost, and the vibration means of the striking means or the vibrating portion is retracted. In the stroke, the cutting edge is paused with the tool edge kept in contact with the cutting point, and when the striking means or the vibrating unit is turned to the pre-vibration advance again, the tool again collides with the tool or the holder holding the tool. A step vibration cutting method characterized by generating a step-like cutting edge locus for cutting and performing intermittent cutting. 2. A tool held movably only in a cutting direction or a holder holding the tool, and a rearwardly extending tool or a holder holding the tool with a clearance of at least both amplitudes in the cutting direction. A step vibration cutting device, comprising: a striking means or a vibrating section provided; and means for applying vibration to the striking means or the vibrating section. 3. In cutting by a milling tool, between a rear end portion of a holder holding the milling tool and circumferential vibration applying means, or between a shank of the milling tool and a holder to which circumferential vibration is transmitted. In addition, a clearance of both amplitudes or more is provided to allow the rotation of the milling tool in the circumferential direction up to this limit, and at the time of movement of the circumferential vibration applying means or the holder in the normal rotation direction in each vibration, Due to the loss of clearance, cutting is performed with the milling tool, and when the circumferential vibration applying means or the holder is moved in the reverse rotation direction, cutting is paused while the milling tool is kept at the cutting point by the clearance, and then circumferentially again. When the vibration imparting means or the holder starts to move in the normal rotation direction, it repeatedly collides with the holder or the shank and repeats the step-like tool edge trajectory for cutting with the milling tool. Step vibration cutting method characterized by intermittent cutting form. 4. A striking means is provided on the circumferentially oscillating main shaft, a tongue portion is provided at a rear portion of a holder for holding a milling tool, and the striking means is provided with a circumferentially extending portion between an outer surface of the tongue portion. A step vibration cutting device, wherein a clearance C having an amplitude or more is provided. 5. A milling tool having a tongue portion on the rear side of a circumferential vibration main shaft coupled to a means for applying low frequency vibration is held by a holder, wherein the holder has a circumferential surface between the tool and an outer surface of the tongue portion. A step vibration cutting device comprising a pair of striking means or a vibrating portion for providing a clearance having both amplitudes in both directions. 6. A cutting means or a vibrating portion provided behind a milling tool or a holder for holding the milling tool with a clearance equal to or greater than both amplitudes is provided for cutting with the milling tool. While oscillating the means or the vibrating section in the feed direction, the feed speed fw is set to fw <2πAF (A: amplitude, F:
Frequency) by periodically hitting and driving the milling tool or the holder holding it in the feed direction, and cutting only during the pre-vibration process in which clearance has been lost. The cutting is paused with the tool kept in contact with the cutting point, and when the striking means or the vibrating unit has turned to the pre-vibration advance again, the cutting tool re-collides with the cutting tool or the holder holding the same, and the cutting is performed. A step vibration cutting method characterized by generating a step-like cutting edge trajectory for performing intermittent cutting. 7. A milling tool held movably only in the feed direction or a holder holding the milling tool, and a milling tool or a holder holding the milling tool is provided with a clearance of at least both amplitudes in the feeding direction. A step vibration cutting device comprising: a striking means or a vibrating section disposed rearward; and means for applying vibration to the striking means or the vibrating section.