JPS62140701A - Superposed vibration cutting method - Google Patents

Abstract

PURPOSE:To enable precise cutting, by making a cutting tool to vibrate with a high frequency of an ultrasonic wave band in a back component direction, superposing different frequencies, and performing high speed cutting, for instance, at 200-300m/min so as to produce needle-shaped chips for reducing cutting resistance. CONSTITUTION:A cutter is given a vibration of frequency (f) and amplitude (a) by an ultrasonic wave oscillator, vibrator and horn in a back component direction, and a high speed cutting is performed by giving a vibration of frequency F and amplitude A produced by driving of an electro-hydraulic equipment superposedly given. In case of a conventional cutting, OO' proceed by a distance of S during one turn, and the areas corresponding to areas OO'O1O1 are continuously and evenly cut, while, in case of a vibration cutting of F.A, the area is divided into intermittent areas AA'BB' and in case of a vibration cutting of (F.A+f.a) the area is finely divided into micro areas abcd and is cut. The cutting time tc of an intermittent cutting force wave form 23 becomes 1/2 of a cycle T and a precise cutting is enabled by drastic decreasing of the frictional resistance and also by the decreasing of the cutting force and displacement amount.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a superimposed vibration cutting method for cutting fine chips.

(Prior art) A cutting tool is vibrated in the cutting direction at a frequency f and an amplitude a, and
A vibration cutting method in which precise cutting is performed by cutting at a cutting speed V of 2πaf and using a pulsed cutting force waveform that produces continuous flow-shaped chips is invented by the present applicant and is well known.

Subsequently, the present applicant invented a superimposed vibration cutting method using an intermittent pulse cutting force waveform, in which the above-mentioned continuous pulse cutting force waveform was regularly thinned out, as a method to further reduce the cutting force and enable ultra-precision cutting. . This is done by vibrating the tool cutting edge in the same direction as the cutting direction at a low frequency F and amplitude @A in the audio range and a high frequency f and amplitude a in the ultrasonic range.
This system performs ultra-precision cutting by cutting at a relatively low cutting speed V of f and applying an intermittent pulse cutting force waveform.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional technology, it is not possible to sufficiently reduce the cutting force, and therefore high-speed cutting is not possible, cutting time becomes long, and cutting efficiency cannot be improved. There was a problem.

(Means for Solving the Problems) The present invention has been made by focusing on the relationship between the vibration speed and the cutting speed when the cutting tool is vibrated. I thought that all the methods had been investigated, devised, and exhausted, but subsequent research revealed that by selecting the vibration motion locus of the cutting edge of the cutting tool, it was possible to shred chips and generate a pulsed cutting force waveform for precision cutting. It was discovered that there is a cutting system that does this. In other words, the cutting edge of the cutting tool is moved in the direction of the thrust force at a high frequency f in the ultrasonic range.
By vibrating with amplitude a and cutting at a fast cutting speed of, for example, 200 to 300 m/+++in so that the flank surface of the cutting tool does not come into contact with the workpiece, the chips are finely shredded, and the pulsed cutting force waveform acts to cut the chips into precision pieces. It was invented that cutting can be realized. Now, in order to perform ultra-precision cutting, it is necessary to reduce the cutting force acting on the workpiece as much as possible.

The present invention was devised and devised to satisfy this condition by finely pulverizing the chips.

In other words, the cutting tool is vibrated in the direction of the thrust force at a high frequency f and amplitude a in the ultrasonic range, and the vibration state of the frequency F and the amplitude A where F<f is superimposed in the direction of the thrust force to determine the cutting speed. The inventors have invented a method and apparatus for superimposed vibration cutting by cutting at a high speed of, for example, 200 to 300 m/min, and crushing chips to be precisely cut using the intermittent pulse cutting force waveform. 200 to 300 m/m for the low cutting speed of 20 m/min or less and the continuous chips of the cutting type in the superimposed vibration cutting mentioned above.
This cutting method is characterized by a high cutting speed of 500 m/min to 500 m/min, and cutting by generating loose chips in the form of powder or needles.

(Example) The principle of the present invention will be explained with reference to FIG. FIG. 1 shows a tool-workpiece vibration system in turning processing. Figure 1 shows the behavior of a workpiece that moves around due to thrust force, and by analyzing it, precision machining technology can be devised. In FIG. 1, if we assume that there is no need to consider spring k and dashpot C, the surface roughness will be 0. Ultra-precise cylindrical machining with a roundness of 09 and a cylindrical degree of 0 is achieved. Actual machine tools are assembled in such a way that k and C cannot be ignored. When turning using the lathe, P+psinω as shown in Fig. 2(a). When a cutting force waveform of t is applied, the displacement of the workpiece in the direction of the back force is
Ha, ω. ) When ω7, x=H, and there is no temporal variation of the workpiece, resulting in a static displacement when only the static load p acts, making precision machining possible. Conventional high-speed cutting is based on this concept. For this waveform in Fig. 2(a),
As shown in Fig. 2(b), action time tc, period T = 1/f
=-≦pulses ω When the cutting force P acts on the workpiece, the displacement X of the workpiece in the direction of the back force is ω) When ω7, z = −j−5−LT
', the workpiece no longer changes over time and becomes a static displacement, and the amount of displacement is drastically reduced to tc/T in Figure 2 (,), realizing precision machining.

This is vibration cutting.

Following this cutting method using the waveform of FIG. 2(b), we invented a cutting method using an intermittent pulse cutting force waveform in which the continuous pulse cutting force waveform is thinned out as shown in FIG. 2(e). This intermittent pulse cutting force can be generated by further dividing the pulse of action time tC shown in FIG. 2(b) into smaller parts as shown in FIG. ) is obtained by repeating the waveform obtained by thinning out the pulses after applying the pulses at period T". In Fig. 2(c), the isometric cutting force P' at this time is obtained by t'c
Then, P' = PXV =, and when the displacement of the workpiece in the direction of the thrust force ΔxFE and the period T' = E, ω'〉ω)
At ω7, ω′ tc t′cp Δz=(7x〒)×7. That is, Fig. 2(c)
By setting the waveform to , the displacement can be reduced to 7 of the displacement at t'c in FIG. 2(b).

The displacement ΔX exhibits a relationship parallel to the time axis as shown in FIG. 3(a), and the workpiece does not oscillate, making ultra-precision cutting possible.

FIG. 2(d) often occurs when ω' is smaller than ωn.

The behavior of the workpiece is as shown in Figure 3(b). Although the workpiece swings as shown, the cutting edge of the tool comes into contact with the workpiece only near the zero point, creating a cutting mechanism that generates chips in almost the same state as when the workpiece is stationary. At this time, since the cutting force of tc is p'-TxP, the amount of displacement is reduced to tc/T when vibration cutting is performed using only FA and p is directly applied, making ultra-precision machining possible.

A detailed explanation will be given below based on an embodiment shown in one figure. In Figures 4 and 5, the bite shank 1 vibrates longitudinally at an excitation frequency of 20Kl (z) by the vibrator 4 and horn 5, and is fixed using the nodes of the clamping fittings 11 and 12, and then tightened. It is fixed to the tool holder 1o with the bolt 13.The tool tip 2 attached to the tip of the tool holder 1o has a vibration frequency f in the direction of the arrow 3.
, ultrasonic vibration with amplitude a. Then, a mounting plate 6 for attaching to the cutting tool holder 10 is fixed to the notebook end surface of the horn 5, and this vertical vibration system cutting tool is fixed to the cutting tool holder. The bi 1-holder 10 can slide on a guide surface 8 mounted on a lathe carriage 7 with little friction using one ball or roller 9. Mounted on the lathe carriage is an electro-hydraulic system consisting of a servo valve 17 driven by a control device 18 and an actuator 16 driven by a hydraulic system 19. By connecting the cutting tool holder 10 and an electro-hydraulic device and driving the electro-hydraulic device, the tip of the cutting tool tip is set to a sinusoidal waveform with a frequency F of, for example, 1007, and an amplitude A of, for example, half amplitude of 0.
．． It can be vibrated in the direction of the arrow 20 by 1 mm. On the other hand, for the amplitude a of the frequency f=20KIIz, the maximum single amplitude of 30 μm is obtained by operating the ultrasonic oscillator 15. In this way, the bi-1 shank is vibrated superimposed in its axial direction so that the vibration state of the cutting edge becomes frequency f, amplitude a and frequency F, amplitude A, feed S22 is applied, and the lathe main shaft A workpiece 21 attached to a chuck and rotating at a high speed at a cutting speed V is subjected to vibration cutting.

FIG. 6 is a diagram showing a cross section perpendicular to the rotation center axis of the cutting part at that time. As shown in the figure, the cut surface has minute irregularities. FIG. 7 is a plan view of this.

In the figure, the motion locus of the cutting edge during conventional cutting where A=0°a=O shows a straight line 00'. In the case of only F-A, curve ABCD is shown, and when the workpiece rotates once, the cutting edge advances by S, moves to curve A'B'C'D', and reaches the area AA'BB' shown by diagonal lines. The corresponding portion is generated as chips in a time period of 1/2 of the period 1/F of one cycle of vibration of the cutting tool. When cutting by superimposing f and a on this, the cutting mechanism becomes a cutting mechanism that subdivides the area AA'BB' into a group of minute areas abCd and generates them as chips. In other words, in conventional cutting, a straight line 010 parallel to 00' and a distance S
In contrast to continuous and uniform cutting of the area corresponding to the area 00'0□O machining' between (F-A)
+ In vibration cutting of (f-a), this area AA' BB
' is characterized by cutting by cutting the area abed by dividing it in small increments. The cutting time tc for the minute area abcd at this time is 1/2 of T=1/f. When the intermittent pulse cutting force waveform 23 in the present invention is illustrated with the pulse cutting force being P, it becomes as shown in FIG.

That is, each cutting time and period is t. :2o,o
ooXT(S), T=2oooo(S), t'c=-x
−(S)l T″=earth.The above-mentioned cut+00 2
100 cutting force P" becomes TP, and the displacement amount is reduced to 1/2 of that in vibration cutting with only F-A. At this time, the ultimate value of tc = - knee X - LS is 20.000 2 When cutting in small steps with a short cutting time, the pulse cutting force P
In reality, F
-The amount of displacement of the workpiece is drastically reduced to about 1/2 to 175 compared to when only A is used, making ultra-precision machining possible.

Another embodiment of the present invention will be described with reference to FIG. 9, in which a cutting system using a bending vibration type cutting tool is shown in place of the above-mentioned system using a longitudinal vibration type cutting tool.

The bite shank 25 is ultrasonically vibrated at an excitation frequency of 20 K Ilz by a longitudinal vibrator 29 and a horn 28 which are excited by an ultrasonic oscillator 33 .

The cutting tip 26 attached to the distal end face of the shank exhibiting a high-order bending vibration state vibrates ultrasonically in the direction of an arrow 38. This bending vibration cutting tool shank is fixed to the cutting tool holder 32 using a tightening bolt 31 with a U-shaped metal fitting 27 using two locations of a node group formed on the shank.

An electro-hydraulic system consisting of a servo valve 35 driven by a control device 37 and an actuator 34 driven by a hydraulic system 36 is connected to this tool holder. By attaching this device to the lathe carriage, it is possible to vibrate the tool cutting edge in the direction of the feed S30 with the frequency f and the amplitude A38 superimposed on the frequency F and the amplitude A39. The present invention can be carried out by a cutting system in which the workpiece 40 is chucked onto the main spindle of a lathe, rotated at a cutting speed v41, and then cut by the above-described apparatus.

Figure 10 shows a cross-sectional view at right angles to the cutting edge, and the cutting tool used in the present invention has a large clearance angle β as in Figure 6, and a negative rake angle α to prevent the mechanical strength of the cutting edge from decreasing accordingly. It is also a practical feature of the present invention to use a cutting tool with a cutting edge shape as shown in the figure.

The above has described the embodiment in the case of ω>ω' and ω'<ωn in FIG. 2(d), but next.

ω′〉ω, ω′)ω in Fig. 2(c). An example in the case will be described. The electrons of the cutting method at this time are
The purpose of cutting is to vibrate a cutting tool edge which vibrates ultrasonically at a certain frequency f and to vibrate it at a higher frequency f'. Specifically, as described above, there are methods in which the same tool is ultrasonically vibrated at f and f' for cutting, and a cutting tool is vibrated at f or f' and the workpiece is cut at f'.
Alternatively, there are two methods: cutting by ultrasonic vibration separately at f.

Here, the latter method will be explained.

The bite shank 1 includes an ultrasonic oscillator 15 and a longitudinal vibrator 4
and horn 5 cause ultrasonic vibration at a high frequency in the ultrasonic range. The cutting blade tip 2 attached to its tip vibrates ultrasonically in the direction of the arrow 3 with a frequency f and an amplitude a. The tool holder 10 with the vertical vibration system tool shank attached thereto is mounted on a lathe carriage as shown in the figure. The workpiece 42 is attached to the tip of an amplitude enlarging horn 43, which is also a workpiece attachment jig driven by an ultrasonic oscillator 49 and a vertical vibrator 44. A high frequency f' in the ultrasonic range is generated using the ultrasonic oscillator 49 installed separately on this workpiece.
and ultrasonic vibration in the direction of arrow 45 with amplitude a'.

Then, this longitudinal vibration workpiece is fixed to the cylindrical mounting jig 46 using the node of the amplitude amplifying horn 43. Chuck 4 with this cylindrical mounting jig 46 attached to the lathe main shaft
The present invention can be carried out by chucking the blade at 7, rotating it at high speed in the direction of arrow 48, and cutting at cutting speed V and feed S.

The locus of movement of the cutting edge at this time is similar to that shown in FIG. 7th
In the figure, v/F becomes v/f, and v/f becomes v/f'.

Then, P' = - Agency - P valve - LP, and the workpiece T'
2 displacement in the direction of thrust force x=2'T''G=÷・row.f
ω4 = 2πX (300~toooo) of the workpiece vibration system attached to the spindle according to the present invention, which utilizes high vibration frequencies in the ultrasonic range of ' = 60 KHz and F = 20 KI'tz.
is generally low, so it always satisfies the condition ω (=2πf) >> ω1, and even in high-speed cutting of 200 to 300 m/min, it generates finely chopped fine chips and generates pulsed cutting force, allowing precision cutting. It becomes possible. At this time, t, 'c
= - 1 - In reality, the amount of displacement of the workpiece is drastically reduced to about 1/2 to 115 when vibration cutting is performed using only the frequency f and the amplitude a, making ultra-precision machining possible.

The present invention has been described in detail using examples of machining a cylindrical surface using a cutting tool and examples of end face processing. However, the present invention also includes internal processing using a cutting tool, and its cutting edge configuration is based on the continuity of the cutting edge configuration of the cutting tool. It is also applicable to hole drilling using drills, reamers, and end mills. That is, a cutting tool such as a drill, reamer, or end mill can be superimposed with ultrasonic vibration, low-frequency vibration, or vibrating a workpiece in the axial direction of the tool shank, and the main shaft can be rotated at high speed to perform superimposed vibration high-speed cutting.

Furthermore, the present invention can be applied and implemented in the same manner to a grinding tool using fixed abrasive grains formed by fixing natural diamond abrasive grains, artificial diamond abrasive grains, or borazone abrasive grains to the end face and surface of a cylindrical shank. can. To implement the present invention in planar machining, the present invention is carried out by superimposing ultrasonic vibrations or low frequency vibrations on a rotating cutting/grinding tool in the direction of its back force.

(Effect) In the case of Fig. 4, a bite shank with a carbide tip of α=30' and β=45' at the tip is vibrated in the axial direction of the bite shank at a frequency f = 21.7KI (z, amplitude a= 16μm
Ultrasonic vertical vibration is applied to the stainless steel L SUS 30.
4. Rotate a workpiece with a diameter of 40 m++ and a length of 100 m at a lathe spindle rotation speed of 150 Or, p, m, and align the cutting edge with the center bite so that the ultrasonic vibration occurs in the direction of the back force. Install it as shown in the figure and use an electro-hydraulic device to generate a vibration frequency F = 50Hz and amplitude A = 0.2m.
Feed a stainless steel workpiece rotating at a cutting speed of 200 m/min with low frequency vibration at 0.05n+n+/re.
v, depth of cut 0, 5 rm.

By cutting under cutting conditions that use a water-soluble cutting fluid, the cutting force is drastically reduced to approximately 115 to 1/10 of that of normal cutting, and in normal cutting, continuous chips are broken into needle-like discrete chips. There is no oxidative discoloration because the material is not heated to high temperatures, and there is less burr, making it easier to dispose of chips. On the other hand, the tool life is more than doubled, and the cutting depth is exactly as set, making it perfectly round. The company succeeded in achieving the ground-breaking effect of improving the degree of rotation and cylindricity, significantly shortening machining time, and making ultra-precision cylindrical machining possible.

On the other hand, it also has the revolutionary effect of making it possible to precisely machine cylindrical materials such as reinforced plastics and ceramics, which are difficult-to-cut materials using recent new materials.

Next, in the case of Fig. 11, the outer diameter is 20 on and the wall thickness is 3 mm.

A silicon nitride ceramic with a length of 10 mm was subjected to ultrasonic longitudinal vibration at a frequency of f' = 60 KHz and an amplitude of a' = 8 prn, which was attached to a main shaft using an air bearing and driven by a belt using a DC motor at a speed of 200 m/min. A cutting tool was rotated at a high cutting speed of
Ultrasonic longitudinal vibration at 6μm, feed rate 0.02mm/re
By carrying out the superimposed vibration high-speed cutting of the present invention using a water-soluble cutting fluid as V, the cutting resistance can be drastically reduced to about 115 compared to the case of only the frequency f and amplitude a or the frequency f' and amplitude a'. , the tool life was extended by eliminating chipping and breakage of the diamond cutting blade, and the cutting time was reduced to about 115 times compared to conventional vibration cutting.

As explained above, compared to conventional vibration cutting which cannot perform high-speed cutting due to the limitation of cutting speed v < 2πaf, the present invention can cut at a cutting speed of 200 m/min to 300 m/min.
This has the effect of enabling high-speed cutting of 500 m/min, enabling precision cutting by applying a pulsed cutting force waveform, shortening cutting time, and improving cutting efficiency.

[Brief explanation of drawings]

Fig. 1 is a model diagram of the tool-workpiece vibration system in turning processing, and Fig. 2 shows the cutting force waveform in normal cutting, the continuous pulse cutting force waveform in conventional vibration cutting, and the two types generated by implementing the present invention. Figure 3 shows the intermittent pulse cutting force waveform of
The figure shows the displacement of a workpiece when an intermittent pulse cutting force waveform is applied, Figure 4 is a top view of the device when the present invention is applied to turning, and Figure 5 is a cross section of the device in the direction of the bite shank. 6 is a cross-sectional view in the direction perpendicular to the axis of the workpiece including the cutting blade during cutting by implementing the present invention, and FIG. 7 shows the locus of motion of the cutting blade by implementing the present invention. The material is cut into small pieces and the chips are shredded into fine powder.
Fig. 8 is a diagram showing the intermittent pulse cutting force waveform at that time, and Fig. 9 is a bending vibration type cutting tool according to the present invention. FIG. 10 is a cross-sectional view taken in a direction perpendicular to the cutting edge to explain the state of the cutting surface at that time, and FIG. 11 is a diagram showing another embodiment of the present invention. FIG. 2 is a top view of an apparatus for performing superimposed vibration high-speed cutting by vertically ultrasonically vibrating a workpiece, rotating it at high speed, and ultrasonically vibrating a cutting tool in the longitudinal direction of the cutting tool shank in the direction of the back force. 1...Longitudinal ultrasonic vibration system part-time tool 3...Ultrasonic vibration in the vertical force direction f, a 15...20k) Ultrasonic oscillator 20...Low frequency vibration in the vertical force direction F, A23. ... Intermittent pulse cutting force waveform 25 ... Bending vibration system cutting tool 33 ... 60 and seven ultrasonic oscillators 41 ... High cutting speed

Claims (1)

[Claims] A superimposed vibration cutting method in which a tool or workpiece is ultrasonically vibrated in a direction perpendicular to the cutting direction, and the tool or workpiece is cut by applying different vibrations in the cutting direction to fragment and finely cut chips.