JPS6246281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a vibration cutting method in which cutting is performed by vibrating a workpiece or a tool in the cutting direction.

(Prior art) Vibration cutting methods that reduce cutting force at low cutting speeds compared to conventional cutting and smooth surface roughness are conventionally known. It is common to strive for improvement.
Therefore, the cutting resistance becomes large. Therefore, it becomes necessary to drive the vibration cutting device with large vibration energy. As for the vibration driving device, a mechanical-electric type, an electro-hydraulic type, or a mechanical-hydraulic type can produce a larger output than a vibration driving method using a magnetostrictive vibrator or an electric strain vibrator.
Therefore, its frequency is a low frequency of 200Hz or less. After experimenting and putting it into practice, I believe that the highest frequency that satisfies the vibration cutting mechanism with current technology is approximately 100Hz.

The cutting length l _T in one cycle of tool vibration in vibration cutting is expressed by υ/f: cutting speed, f: tool vibration frequency. This l _T is an important factor that influences cutting resistance, surface roughness, etc. As is clear from this relational expression, l _T at a low frequency of about 100 Hz is longer than l _T at a high frequency of 200 KHz in the ultrasonic range. 100Hz vibration cutting and
Comparing with 20KHz vibration cutting, even if the principal force in two-dimensional cutting shows almost the same value, the thrust force in 20KHz vibration cutting is about 1/2 to 1/6 of that in 100Hz vibration cutting.

In Fig. 1, if the frequency of the cutting tool is increased to make the frequency f and the amplitude a in the ultrasonic range, ω _o ≪ ω (ω _o ;
Angular natural frequency of back force direction of workpiece, ω; 2πf)
At that time, thrust force p _t , cutting time t _c ,
Assuming that the period of the cutting tool is T and the spring constant of the workpiece in the direction of the thrust force is k, the displacement waveform of the workpiece becomes linear as shown in FIG. For example, p _t =2Kgf, f=
22KHz, t _c /T=1/7, k=4.55×10 ² Kgf/
mm, ω _o =2π×400rad/s, ν=0.10 (ν=C/Cc, C; viscous damping coefficient of workpiece, Cc;
(critical viscous damping coefficient), the displacement of the workpiece in the direction of the back force x = 0.66 μm.

In this way, when the cutting tool frequency is increased and a pulse cutting waveform is applied, there is no dynamic behavior of the workpiece, and static displacement can be achieved as shown in the figure. 20KHz vibration cutting that uses high vibration frequencies in the ultrasonic range has this feature, but when the energy of the magnetic and electric distortion oscillators is small and the cutting resistance is large, the vibration state of the cutting tool changes and extreme In this case, the amplitude of the cutting edge becomes zero. That is, the cutting time t _c of the pulse cutting force waveform becomes longer, the pulse cutting force waveform peculiar to vibration cutting gradually approaches the conventional cutting force waveform, and the vibration cutting effect disappears.

The deformation waveform of the workpiece in 100Hz vibration cutting that can increase the output is as shown by curve 8. If this curve 8 can be changed linearly as shown in FIG. 5, the cutting area can be increased by low-speed cutting, and precision cutting can be achieved even during heavy cutting. The only concrete way to do this is to reduce the absolute value of p _t itself and make the behavior of the workpiece due to p _t insensitive. Reduction of p _t is achieved by drastically reducing l _T . However, l
The length of _T is determined by cutting speed and vibration frequency. In conventional vibration cutting mechanisms, the cutting tool is vibrated at a single frequency, so l _T is determined in this way, so it has been treated as an unchanging value once the cutting conditions are determined.

It has been known that the cutting effect can be improved by reducing l _T , but in the past, l _T which increases during vibration cutting using low frequency vibrations was considered to be an unavoidable phenomenon.

(Purpose) The present invention subdivides the cutting length to be cut during this cutting time _tc by superimposing 20KHz vibration cutting to sharply reduce the cutting resistance acting on the workpiece as an intermittent pulse cutting force waveform. The aim is to completely eliminate the dynamic behavior of the machine and perform precision machining. In other words, as shown in Figure 6, move the cutting tool in the cutting direction indicated by the arrow.
Ultrasonic vibration (f, a) is generated at a high frequency in the ultrasonic range of 20KHz or higher, and at the same time a low frequency vibration (F,
A), and the cutting speed υ at that time is related to the frequency F of the low frequency vibration and the maximum vibration speed of the amplitude A, and the cutting speed is lower than the maximum vibration speed of the cutting tool as υ < 2πAF. By performing vibration cutting by applying a pulsed cutting force waveform, it is possible to perform vibration cutting at l _T =ν/F without disturbing the vibration state of the cutting tool using a low frequency vibration drive device that can supply large output. , this is divided into small lengths l _T = ν/f by the ultrasonic vibration of the cutting tool, and an intermittent pulse cutting force waveform is applied. In areas where the shape is disturbed, a low-frequency vibration drive device is used to stabilize the vibration state of the cutting edge in the ultrasonic range while reinforcing the energy, reducing the cutting resistance by one order of magnitude, for example, in the case of 100Hz vibration cutting. ,
This dramatically reduces surface roughness to about 1/100 of conventional cutting, smoothes surface roughness, improves machining accuracy, reduces deviations in shape and dimensions after machining, and allows precision machining to be performed with fewer burrs. The purpose is

(Example) FIG. 1 shows a tool-workpiece vibration system in turning processing. Byte 1 according to this figure 1
For example, in the cutting direction, which is the tangential direction of the workpiece 2,
Low frequency F around 100Hz, amplitude A and 20KHz
It is vibrated in the 4 directions with a relatively high frequency f and amplitude a, and a cutting condition of υ<2πAF is given for the cutting speed υ3. The thrust force p _t 5 at that time is the second
The pulse cutting force waveform is as shown in the figure. In the figure, t _c is the cutting time during one cycle of the cutting tool, and T is one cycle of vibration of the cutting tool. In 100Hz vibration cutting, for the angular natural frequency ω _o of the workpiece in the direction of thrust force, ω _o > ω
(ω=2πF) is normal. Now υ = 0.3m/min, F = 100Hz, A = 0.20mm, depth of cut = 0.20mm, cutting width = 1.0mm, rake angle = 0
゜, ω=2πF=2π×100rad/s, ω _o =2π
×360rad/s, k=4.6×10 ² Kgf/mm, ν=
0.055, the dynamic behavior of the workpiece in the horizontal direction due to thrust force _pt in wet two-dimensional cutting of free-cutting brass is shown in Figure 3. The workpiece behaves as shown by the bold curve 8 in FIG. 3 during the t _c cutting time.

In precision cutting, the ideal displacement waveform for the workpiece is not the displacement waveform of curve 8 like this, but a straight line with respect to the horizontal time axis as shown in Figure 5, and in which the displacement x≒0. .

FIG. 9 shows an apparatus for machining cylinders for carrying out the method of the invention. The device body 1 is placed on the lathe carriage 12.
Fix 3. An electric motor 14 is attached to the main body of the apparatus, and a high-speed rotating shaft on which a slider 15 can be mounted eccentrically is rotated at 6000 rpm. This slider is rotated around the central axis 16 by the swinging arm 17 in the illustrated position, and the swinging arm 17 can vibrate around the central axis 16 with an amplitude equal to the eccentricity of the slider. Do it like this. A cutting tool holder 24 is fixed to this swinging arm 17 using a tightening bolt, and a vertical ultrasonic vibration system tool consisting of a longitudinal magnetic strain vibrator 18, an amplitude expansion horn 9, and a cutting tool is installed using its vibration nodes. Install it. When the magnetostriction vibrator 18 is caused to vibrate ultrasonically, the cutting edge of the cutting tool vibrates ultrasonically in the cutting direction indicated by the arrow 21 at a frequency f and an amplitude a having a single amplitude of 10 μm or more. The vibrating arm 1 is rotated by rotating the electric motor 14.
When the tool 7 is vibrated, the tip of the cutting tool vibrates at a low frequency in the cutting direction indicated by the arrow 22 at a frequency F and an amplitude A with a single amplitude of about 0.2 mm. In this way, the superimposed vibration cutting tool 20 is produced, and the present invention can be put into practice. The workpiece 24 is then rotated in the direction of the arrow 23 at a cutting speed υ. Select the cutting speed υ so that υ<2πAF. With such a device and cutting conditions, by applying horizontal feed in the direction of the arrow 26 to the cutting tool shown in the figure and cutting, two-dimensional cutting according to the present invention and vertical feeding can be applied to perform cylindrical machining. It can be carried out.

According to the present invention, the chip shape is chip 9,1
It is divided into blocks with lengths proportional to l _T such as 0, 11, etc., and the blocks are further subdivided into shapes with lengths proportional to l _T in a regular manner. be discharged.

(Effects) The thrust force P _t ' in the method of the present invention is drastically reduced as shown in FIG. For example, stainless steel SUS304, width 1
mm, cutting speed υ=0.3m/min, depth of cut 0.2mm, F
=100Hz, A=0.15mm, f=20KHz, a=15μ
m, rake angle = 0°, the thrust force P _t = 1.8 Kg in the case of wet two-dimensional cutting and only 100Hz vibration cutting is almost zero due to the superimposed vibration cutting of the present invention P _t ′=
It will be 0.4Kg. Another noteworthy effect is that the principal force was drastically reduced from 6 kg in the case of only 100Hz vibration cutting to a value of P _c ′ = 0.6 kg.

Therefore, the displacement of the workpiece becomes a static displacement and the 8th
As shown in the figure, it shows a straight line with respect to the time axis. The amount of displacement x' is equal to or less than that of 20KHz vibration cutting.

By implementing the present invention, for example, the principal component force P _c '=0.4
It has become possible to perform cutting with a very small cutting force that is close to zero, ie, thrust force P _t '=0.1 kg. Furthermore, there was no occurrence of burrs on the end face, and the surface roughness could be reduced to 0.8 μm Rmax.

Next, the effects of the present invention will be explained by illustrating other machining methods and methods of applying the present invention to other tools. FIG. 10 shows a case in which the tool is applied to flat surface machining, in which the cutting tool is vibrated in the cutting direction at f·a and F·A, and the cutting speed υ is set as υ<2πAF to perform planar cutting. As the 100Hz vibration drive device, mechanical, electric-hydraulic, mechanical-hydraulic, pneumatic, and electric types can be used. As the 20KHz vibration drive device, vertical vibration or torsional vibration magnetic distortion, longitudinal vibration type cutting tools using electric distortion vibrators, bending vibration type cutting tools, and torsional vibration type cutting tools can be used. Using this method and device, it has become possible to perform precision flat machining of highly elastic workpieces such as rubber and carbon fiber reinforced plastics.

FIG. 11 shows a case in which the hacksaw blade 27 is vibrated in the cutting direction at f·a and F·A when applied to a hacksaw blade.
Cutting is performed by setting the cutting speed υ to υ<2πAF and applying a constant load p. During this machining, the workpiece may be vibrated at F.A, and the saw blade may be vibrated at f.A. And the same implementation effect can be obtained. Further, the workpiece may be vibrated at f.a., and the saw blade may be vibrated at f.a., F.A, to perform superimposed cutting. This method and apparatus allow precision cutting of ceramics.

By carrying out the present invention using this method and device, cutting time with a hacksaw blade can be shortened, the cut surface can be made smooth, and a cutting effect without burrs or chips can be obtained.

FIG. 12 shows the case where the broach 28 is applied. Up until now, research has been conducted on applying 20KHz vibration cutting alone and on broach cutting using 100Hz vibration cutting, but in the case of 20KHz vibration cutting, the effect is less due to the lack of vibration energy.
In the case of 100Hz vibration cutting, the surface roughness did not become smooth and satisfactory effects were not obtained. By implementing the present invention in broach cutting, the decisive effect in cutting where the principal force is almost zero and the effect of smoothing the surface roughness are simultaneously exhibited, and ideal broach cutting is achieved. It became possible.

FIG. 13 shows the case where it is applied to the file 29.
The file is also a surface brooch. There is an extremely large amount of manual work with files. And it is difficult to finish the inner surface of a deep hole in a hard material. When filing, you want to reduce cutting resistance and finish in a short time. By implementing the present invention, these problems up to now are solved and eliminated. File f・a and F・
The present invention is carried out by superimposing vibrations in the longitudinal direction of the file at A and setting the machining speed υ to υ<2πAF. The pressing force p is reduced, the working time is shortened, and the labor is also reduced, making the sanding work easier. If the present invention is applied to a scraper with a cutting edge at the tip instead of this file, scraping work can be done by superimposed vibration cutting, which will streamline the scraping work, improve the machining accuracy, and reduce the labor involved. available.

FIG. 14 shows the application to a thread cutting tool 30. The cutting area in this thread cutting is wider than the cutting area in normal cylindrical machining. Therefore, cutting resistance increases. Conventionally, when thread cutting, 20KHz vibration cutting has been used with emphasis on the precision of the cut surface. Therefore, vibration cutting has been performed under cutting conditions that do not disturb the vibrational state of the cutting tool tip by dividing the cutting area into smaller sections to reduce the cutting resistance acting on the cutting tool tip. Cutting threads into hardened steel and other materials required quite a long processing time. By carrying out the present invention, the machining time is shortened, and it becomes possible to mass-produce highly accurate screws.

In addition, when processing general reamers and center reamers, the reamer is vibrated by ultrasonic torsion in the circumferential direction using a torsional vibrator, and at the same time, mechanical, pneumatic, hydraulic, electric, or electro-hydraulic methods are used. The present invention is carried out by applying circumferential vibration and rotational motion, and a superimposed vibration reaming effect is obtained, allowing ultra-precision machining of holes.

If applied to a drill instead of a reamer, a superimposed vibration drilling effect can be obtained, allowing precision drilling of holes.

In addition, when milling with a milling machine, the milling cutter or end mill is vibrated by ultrasonic torsion in the circumferential direction using a torsional vibrator, and at the same time, vibration is generated in the circumferential direction by mechanical, pneumatic, hydraulic, electric, or electro-hydraulic methods. The present invention is carried out by applying rotational motion, and the effect of superimposed vibration milling or superimposed end milling can be obtained to perform ultra-precision flat processing.

Figure 15 shows the burr that appears on the end face of a punched and plastic-worked workpiece, and a cutting tool used when mass-producing a thin plate material into a cross-sectional shape that cannot be processed by punching by sending the cutting tool in a direction perpendicular to the punching direction. This is a case where it is applied to

The cutting edge shape at this time is a general cutting tool cutting edge shape as shown in the figure, and the cutting area 32 thereof is generally wide. Therefore, cutting resistance increases. Furthermore, since it is necessary to completely eliminate the generation of burrs, it is necessary to perform cutting with almost zero cutting resistance, which is closely related to burrs. By implementing the present invention, these problems can be solved at once.

SUS304, plate thickness 0.3mm, υ = 300mm/min, cutting area 0.5mm ² , F = 100Hz, A = 0.15mm, f = 20KHz,
The side surface of a hole punched under the cutting condition of a = 15 μm is subjected to superimposed vibration cutting according to the present invention, and the workpiece is mass-produced and punched into a curved surface as shown in the figure. The workpiece is precisely machined without the occurrence of burrs. It was very successful.

FIG. 16 shows a case where the present invention is applied to a cutting blade 33. In this case as well, the blade 33 is vibrated in the cutting direction at a frequency F and amplitude A of about 100 Hz and a frequency f and amplitude a of 20 KHz or more, and the cutting speed υ is changed to υ
Superimposed vibration cutting is performed as <2πAF. By implementing the present invention, even when cutting a thick plate, most of the cross section can be cut by shearing,
We succeeded in processing the cut surface with a smooth cross section.

FIG. 17 shows a case in which the present invention is applied to a punch when punching is performed using a punch and a die. Conventionally, vibratory punching has been attempted by adding ultrasonic vibrations of 20 KHz or higher to a punch, but the ultrasonic vibrations of the punch tend to stop due to insufficient vibration energy, and the processed surface is rough, making the effect of adding ultrasonic vibrations difficult. could hardly be said to be sufficient. Until now, we have longed for the creation of an ultrasonic transducer with high output, but no transducer has yet been completed that can meet those expectations. However, according to the present invention, it has been possible to punch punches weighing several tons using a new energy utilization method that combines a conventional vibrator and a low-frequency vibration drive device. This paved the way for application to processing.

That is, the punch 33 is vibrated in the punching direction at an ultrasonic frequency f and an amplitude a using a magnetic or electric flexure vibrator, and this is vibrated at a low frequency F and an amplitude A of about 100 Hz using an electro-hydraulic system. The present invention is carried out by vibrating and punching. The vibration mode of the punch during processing is vibrated without being disturbed, and the above-mentioned vibration cutting mechanism repeats shear deformation in small increments, making it possible to punch out the entire processed cross section with uniform shear deformation. .

The above describes the specific effects of the present invention based on the ultrasonic frequency.
20KHz, and the low frequency vibration frequency is 100Hz, but if the device is improved in the future and the low frequency frequency is increased to 500Hz or 1000Hz, the present invention will be implemented at higher speed cutting, and the effect of implementing the present invention will be improved. is obtained.

On the other hand, in carrying out the present invention, the explanation has been made based on a method in which ultrasonic vibration energy and low-frequency vibration energy are separately installed and used in a superimposed and combined manner. In the case of grinding/plastic working resistance, the shape of the input waveform of the ultrasonic vibration energy applied to the ultrasonic vibrator using only ultrasonic vibration energy does not have the steady waveform as described above, but instead uses the low-frequency vibration described above. 100Hz, which is several F.
Alternatively, the present invention can be implemented and the implementation effect obtained by providing a modulated waveform with half amplitude 2a of 500 Hz and 1000 Hz and cutting under the condition of υ<2π(2a)f. It should be noted that all of these are included in the present invention.

[Brief explanation of the drawing]

Figure 1 shows a model of the tool-workpiece vibration system in turning processing, and is a diagram explaining the direction of vibration of the tool, and Figure 2 shows the relative effects during one cycle of vibration of the tool in 100Hz vibration cutting F.A. time t
_Figure 3 shows the curved dynamic behavior waveform of the workpiece in the direction of the thrust force when the pulsed thrust force waveform in Figure 2 acts on the workpiece. Figure 4 is a diagram showing an extremely short pulsed thrust force waveform with an extremely short action time t _c during one cycle of vibration of the cutting tool in 20KHz vibration cutting f・a, and Figure 5 is a diagram showing the pulsed thrust force waveform of Figure 4. FIG. 6 is a perspective view showing a chip shear cross section obtained by the method of the present invention; FIG. 8 is a diagram showing the drastically reduced pulsed thrust force obtained by the method of the present invention, and FIG. 8 is a straight line in the direction of the drastically reduced thrust force when the pulsed thrust force waveform of FIG. 7 acts on the workpiece. FIG. 9 is a front view of an embodiment of an apparatus for carrying out the method of the present invention, FIG. 10 is a diagram showing the planing method according to the method of the present invention, and FIG. 11 is a diagram showing the planing method according to the method of the present invention. Figure 12 is a diagram showing a cutting method using a saw blade, Figure 12 is a diagram showing a broaching method using a broach according to the present invention, Figure 13 is a diagram showing a file finishing method using a file according to the present invention, and Figure 14 is a diagram showing a method according to the present invention. FIG. 15 is a diagram showing a method for cutting a thread using a thread cutting tool according to the method of the present invention; FIG.
FIG. 16 is a diagram showing a cutting method using a punch according to the method of the present invention, and FIG. 17 is a diagram showing a punching method using a punch according to the method of the present invention. 1... Bit, 2... Workpiece, 3... Cutting speed, 4... Vibration direction, 21... Ultrasonic vibration direction,
22...Low frequency vibration direction, 27...Gravity vibration cutting saw blade, 28...Gravity vibration cutting broach, 29
... Weight vibration cutting file, 30 ... Weight vibration cutting thread cutting tool, 31 ... Weight vibration cutting general tool tool, 32 ... Weight vibration cutting punch.

Claims (1)

[Claims] 1 The workpiece or tool is vibrated in the cutting direction by superimposing low-frequency vibrations with a low frequency frequency F and amplitude A and ultrasonic vibrations with an ultrasonic frequency f and amplitude A, and the cutting speed υ
A superimposed vibration cutting method characterized by performing vibration cutting at a speed lower than the maximum vibration speed of low-frequency vibration, and cutting by applying an intermittent pulse cutting force waveform to the workpiece.