JPS6147641B2 - - Google Patents

Description

[Detailed description of the invention]

Cutting speeds have become increasingly faster in recent years. High-precision machining is becoming possible. However, although this high-speed cutting has the effect of improving machinability, the current situation is that it is very difficult to deal with continuous high-temperature chips. In addition, unmanned
Although the trend toward robotization is remarkable today,
In many cases, unmanned or robotic production processes have not been realized due to the lack of chip processing technology. The ideal method of chip disposal is to cut continuous chips into pieces and collect them using a dust collector or the like. It is also hoped that these shredded chips can be used to strengthen plastic materials. The present invention was invented to meet these expectations.In two-dimensional cutting, the cutting tool is vibrated ultrasonically in the direction of its back force, cutting is performed at a high cutting speed of 200 to 300 m/min or more, and the feed is adjusted to an amplitude. By cutting with sufficient cutting fluid at a minute feed rate of, for example, about 1/50 of (half amplitude), all industrial materials from plastic to carbon steel can be cut into acicular chips. This invention relates to an innovative chip cutting precision turning method that allows precision turning to be performed with conventional turning accuracy without adversely affecting shape accuracy such as roundness. Next, the present invention will be explained in detail with reference to the drawings. FIG. 1 shows a case where a plate-shaped workpiece 1 having a thickness t and a length l is two-dimensionally cut by applying a depth of cut S to a tool 2 at a cutting speed v. The chip shape at this time is generally continuous like chip 3. Therefore, in the past, tools were equipped with chip breakers, etc.
Attempts have been made to break up these continuous chips using methods such as vibration feed cutting. Although these seem to have been successful for some specific cutting conditions, they have not yet been put into general use. That is,
If the machining accuracy is not affected, the chips may not be divided enough, and if the chips are divided, the machining accuracy will deteriorate and the production efficiency will decrease.It is practical to satisfy both conditions. At present, no method has been developed yet. As shown in FIG. 2, move the tool 2 in the cutting direction 4,
That is, it has been found through long-term research on vibration cutting that the length of chips 3 becomes longer like chips 5 by cutting with vibration in the direction of the principal force component. In research on vibration cutting, it has been found that cutting by vibrating a tool in the direction of thrust force or in the direction of feed force is a method that cannot be put to practical use except in special cases. For example, in the back force direction, there is a phenomenon in which the cutting surface of the workpiece is impacted by the flank of the cutting tool, which damages the tool cutting edge and makes cutting impossible. It is said that this is not a common method. However, the inventors have discovered that the above phenomenon only occurs at low cutting speeds of 100 m/min or less, which have been conventionally performed. In other words, keeping the tool flank surface out of contact with the workpiece surface means that when the frequency f and amplitude a of the tool are constant, the cutting speed v has not been considered in the past.
200m/min, 300m/min, 400 over 100m/min
This can be achieved by cutting at a high cutting speed of m/min, and by cutting with the depth of cut S much smaller than the amplitude a, the chips are broken into pieces and the surface roughness of the cut surface is reduced by several degrees. μm
It was determined that precision turning can be performed as Rmax. In vibration cutting in the principal force direction, we have been too preoccupied with the fact that the cutting speed at which various effects can be obtained is approximately 50 to 60 m/min, and have long overlooked the challenge of cutting at an order of magnitude higher cutting speed. Recently, in vibration cutting in the principal force direction, excellent cutting effects can be obtained at low cutting speeds of about 50 to 60 m/min or less, but with the vibration cutting method of the present invention, it is possible to obtain excellent cutting effects at low cutting speeds of about 300 to 300 m/min.
We have investigated and discovered that this can be achieved at high cutting speeds of around 400m/min to 500m/min. That is,
The chips are finely shredded, and therefore the cutting force waveform becomes a pulsed cutting force waveform, and the cutting heat also becomes pulsed, so that an effect similar to the effect in the principal force direction can be obtained without increasing the cutting temperature. It was discovered that this method has an epoch-making effect that enables precision machining. In Fig. 3, the tool 2 is vibrated in the direction of the thrust force 12 at a frequency f and an amplitude a, and the cutting speed v is set to a high cutting speed of 200 m/min or more as described above, and the feed amount (depth of cut) is Two-dimensional cutting is performed by giving S. At this time, the clearance angle θ of the tool is determined by the frequency f, the amplitude a, and the cutting speed v, so that the tool clearance surface does not come into contact with the surface shape of the cutting surface approximated by a triangular waveform as shown in the figure. . When the present invention is carried out as shown in FIG. 3, in the conventional cutting method, the tool 2 advances at a constant speed v in the length direction of the workpiece as shown in FIGS. 1 and 2.
The cutting part 16, which has an elongated area l×S shown by diagonal lines, is cut all at once, resulting in long continuous chips 3 and 5.
If sin ωt, then the tool tip advances in a triangular waveform b', which is approximated by the motion locus of the cutting tool tip drawn by the combination of the vibration velocity of the cutting tool and the cutting speed v, expressed as aω cos ωt. A small rectangular block 6 with a small area indicated by diagonal lines in the figure,
7, 8...... will be cut. That is, in Figures 1 and 2, the length of the workpiece l
was the cutting length, but by implementing the present invention, it is in the form of a set of minute lengths divided into minute lengths as shown in FIG.

It can be cut by dividing it into small pieces according to [Formula]. Since it is a combination of both speeds,
As shown in the figure, these small blocks 6, 7, 8... cannot be divided parallel to the direction of cutting speed v.
The minute areas that are subdivided in the cutting direction from the inside of the workpiece toward the workpiece surface for each cycle of tool vibration expressed by amplitude a, frequency f, and cutting speed v, which will be described later, are arranged so as to be inclined in the direction of cutting speed v. takes shape. Therefore, peaks and valleys occur, and the cut surface shape becomes an uneven surface. And in order to cut this,
The chips were perfectly shredded, and the chips were 13.1
4,15...... Depth of cut (feed amount) S from the cutting surface with an uneven surface shape having the top of the mountain and point a
When two-dimensional cutting is performed by giving , the peak of the peak moves to point b, and the difference between the peaks of the peak corresponds to the depth of cut (feed amount) S. Similarly, small blocks 9, 10, 11... are formed and chips are shredded. One of the features of the present invention is that this tool is provided with a relief angle θ, which will be described later. The cutting shown in FIG. 3 is performed by the method shown in FIG. That is, the pipe-shaped workpiece 1 is chucked to the main spindle of the lathe and rotated at high speed to increase the cutting speed v.
shall be. An ultrasonic vibrator 17 is glued and fixed to the tail of the bite shank 2, and the bite shank is vibrated longitudinally by ultrasonic waves with a frequency f and an amplitude a in the direction of the arrow 14, and a cutting tool tip is glued to the tip of the bite shank to create a two-dimensional structure. Form a cutting edge for cutting. Then, the end face of the pipe-shaped workpiece is two-dimensionally cut by applying a feed rate of Smm/rev. In other words, both ends of the cutting edge should not be in contact with the workpiece, and the two ends of the cutting edge should not be in contact with the workpiece.
Cutting is performed in a state where only component force acts. At this time, the feed Smm/rev is made smaller than the amplitude a of the bite. For example, a=16μm, S=0.3μ
m/rev to about 3 μm/rev. The motion locus of the cutting edge is synthesized by the curve represented by the displacement a sin (2πf)·t of the cutting tool and the cutting speed v, and is represented by a curve c as shown in FIG. 5A. At this time, since the cutting speed is fast, this can be approximated and considered as a triangular waveform d. It is expressed as =2a, ==v/2f, and is determined as tanθ=〓〓=4af/v. This θ is important, and the clearance angle θ' of the cutting tool needs to be larger than this θ. On the contrary, after setting the relief angle θ' of the cutting tool and forming the cutting tool, when the frequency f and the amplitude a are constant, the cutting speed v is increased, contrary to the case of vibration cutting in the principal force direction. By selecting in the direction of When cutting starts from the end face of the workpiece and each part of the end face reaches a constant feed rate Smm/rev, the cutting surface becomes a triangular wave shape ABCDEFG as shown in Fig. 5 (b).
Furthermore, as the workpiece rotates once, the cutting edge of the cutting tool advances by the feed S, and the part shown with diagonal lines,
BCIH, DEKJ in the next cycle of vibration, FGML in the next cycle of vibration, etc. are intermittently divided into pieces, and each small block is generated as chips and cut. The cutting direction forms an angle θ with respect to the direction of the cutting speed v, and is a direction from the inside of the workpiece toward the surface of the workpiece. The angle θ is smaller than the clearance angle θ' of the cutting tool and is expressed as tanθ=4af/v. Cutting length in one cycle of cutting tool

If a = 16 μm, since a ² = 0, it can be considered that Δl = v/2f. That is, in FIGS. 1 and 2, the cutting length was the length of the workpiece l, but in the present invention it is v/2f,

The length of the workpiece l is expressed by the set of lengths Δl of the small blocks that have been shredded, and the fine chip shredding cutting that generates chips from these divided small blocks is It becomes a mechanism. The depth of cut (feed) at this time is expressed as 2S cosθ, and the depth of cut (feed) in the cases of Figures 1 and 2
It is approximately 1.5 times larger than . The acting time of the cutting force at this time is 1/2 of one cycle of vibration of the cutting tool, and the cutting force waveform is a pulse-like cutting force waveform. By implementing the present invention, as a cutting mechanism that generates shredded chips, an epoch-making effect can be obtained in which a pulsed cutting force waveform with a short period and a short action time, which is ideal in a cutting force waveform, can be applied to a workpiece. It will be done. In addition to this, turning work includes cylindrical turning as shown in Figure 6.
There is a face turning process of the end face shown in Fig. 7, a boring process shown in Fig. 8, and a parting process shown in Fig. 9. Each figure shows a basic implementation method when implementing the present invention in each of these operations. In the case of the parting shown in FIG. 9, as can be easily understood from FIG. 4, the direction of vibration of the cutting blade is from the outer periphery of the workpiece toward the center of the workpiece, that is, in the radial direction. At this time, if the parting length is long as shown in the left diagram of FIG. 9, a back taper is provided from the tip of the cutting blade to prevent abnormal friction on the side surface of the cutting blade. In the case of cutting off a pipe as shown in the right diagram of FIG. 9, it is possible to cut off the pipe without providing a back tape. In order to smoothly carry out the present invention and to achieve the ideal effect, it is important to select the relief angle of the cutting edge that participates in chip formation, as described above. The explanation for cylindrical machining using a cutting tool with a nose angle of 90° in Figure 6 lies in the selection of the side clearance angle of the side cutting edge. Then, in a horizontal section including the tip of the tool cutting edge and the center axis of rotation of the workpiece, the transverse blade has a frequency f and an amplitude a in a direction that is at an angle with the tool feed direction from the outer periphery of the workpiece toward the center of the workpiece. to generate ultrasonic vibration. At this time, consideration must be given to prevent the front flank of the front cutting edge of the tool from acting. In other words, it is important to position the front cutting edge in the same position as the vibration direction or to give it a relief angle γ, that is, to make the nose angle smaller than 90° so that the front cutting edge does not come into contact with the workpiece at all. . In the case of a round tip cutting tool, the side relief angle and front relief angle are the same, so three-dimensional cutting is performed so that the feed direction and vibration direction are not the same. Another feature of the present invention is that the clearance angle is specified, and the clearance angle is larger than the 7-8° angle of conventional tools. As a result, the mechanical strength of the cutting edge decreases, so the rake face is reinforced by giving a negative rake angle (+α) according to the strength of the workpiece. The front cutting shown in FIG. 7 and the boring shown in FIG. 8 are carried out in the same manner as shown in FIG. 6. As can be seen from these figures, the present invention can be applied to all types of turning processing including thread processing. In the figure, the case of a vertical ultrasonic vibration type bite shank is explained, but the same procedure can be applied to a bending vibration type bite shank or a torsional vibration type bite shank. As described above, the cutting length is subdivided into lengths of approximately v/2f. Next, we will consider how to further divide this into extremely fine pieces. As can be seen from the formula v/2f, it is no longer possible to devise a method for this by manipulating only v and f. It becomes necessary to add a separate method. If this cutting length is divided into smaller sections, the surface roughness can naturally be made smoother. A method suitable for this purpose is devised as shown in FIG.
FIG. 10 shows the case of high-speed two-dimensional cutting. In other words, as mentioned above, the tool 2 has a frequency f,
Vibrate in the direction of arrow 18 with amplitude a, cutting speed v
The uneven surface obtained by cutting with ABCDEFG…………
The triangle 19 of the protruding peak is cut using an ordinary cutting tool 21 fixed to a tool post at a distance a little behind the vibrating tool 2. The point where the cutting edge X of this tool 21 is located is the amplitude 2a of the tool 2
Within. In the case of FIG. 10, the tool 2 is located at the same position where the vibration is stopped, that is, at the midpoint of 2a shown in the figure. When cutting in this way, tool 21 deletes part of the triangular area 19 where area DEKJ would be cut using tool 2 only, so the area is smaller than area DEKJ.
D′E′K′J′ will be cut. That is, the cutting length can be shortened. The length of the cut made by the tool 21 is also short and the cut is interrupted, so the chips become fragmented and even thinner. The present invention is carried out by the method shown in FIG. cutting surface in phase with
It also occurs when cutting A ₁ B ₁ C ₁ D ₁ E ₁ F ₁ G ₁ . The chips in this case are continuous. However, the phase gradually shifts and shredded chips are generated again. This tends to occur when the feed is relatively large and close to the amplitude. Therefore, the chip shape is a mixture of finely chopped chips and continuous chips here and there. The position of the cutting edge of the tool 21 in FIG. 11 is a feed amount S from each peak A, C, E, G of the uneven surface ABCDEFG formed by the amplitude 2a of the tool 2. By using the tool 21 installed at such a cutting edge position, a small area corresponding to a part of the triangle 23 in the continuous area 22 is intermittently deleted when the tool 2 alone is used, and this is removed by the vibrating tool 21. Chips can be shredded by cutting 24 portions of the area of the glyph to facilitate full implementation of the chip shredding of the present invention. That is,
This is a case where the cutting edge of the tool 21 is placed near the peaks of an uneven surface such as an ACEG on the cutting surface that is formed when the tool 2 vibrates and moves away from the workpiece 1. At this time, since no large cutting force acts on the tool 21, no mechanical consideration is required for the tool 21, but it is of no use in improving the surface roughness. Therefore, within the _{amplitude 2a} of the tool 2, the _uneven surface is It is conceivable to install the tool 21 near the valley. With this arrangement, the area to be cut by the vibrating tool 2 becomes smaller and smaller (area 26), and the length of the chips becomes shorter and shorter. The surface roughness is shown in Figure 11.
It is smoother than in Figure 10. However, tool 2
The area at 1 is like the area 25 shown in the figure, and the area at 1
The tool 21 has a larger area than the area 23 in FIG. 1 and the area 19 in FIG. The installation position of the tool 21 with respect to the tool 2 within the amplitude 2a as described above is a feature of the present invention. These positions are selected depending on the cutting condition. Then, cutting can be carried out under optimal chip cutting conditions and cutting conditions that provide a smooth surface roughness. FIG. 13 shows the relationship between the mounting positions of the tool 2 and the tool 21 in the case of cutting the end face of the pipe-shaped workpiece 1. The workpiece 1 is rotated at a constant rotation speed n and the cutting speed v
As explained in Fig. 5, an ultrasonic vibration cutting device that causes the tool cutting edge to vibrate ultrasonically at frequency f and amplitude a in the direction shown by the arrow is mounted on the tool post on the lathe carriage, and the tool 21, for example, on the tool post opposite the carriage, with the rake face facing the lathe bed surface in the opposite direction from the rake face of the tool 2, so that the cutting edge position is at the position explained in Fig. 10. The present invention is carried out by adjusting the following. Since tool 21 does not vibrate like tool 2,
There are no restrictions and the clearance angle is set to about 7 to 8 degrees. A method of implementing the present invention for general turning processing is shown in FIGS. 14 to 17. Fig. 14 shows the case of cylindrical turning, Fig. 15 shows the case of face turning of the end face, Fig. 16 shows the case of boring, and Fig. 17 shows the case of parting. In this case, the manner in which various angles are given to the tool 2 and the direction of vibration are the same as in the case of FIGS. 6 to 9 described above. As shown in each figure, the cutting edge of tool 21 is given the cutting depth t or the feed from the outer circumference of the workpiece so that the cutting edge of tool 21 is the same distance from the center of rotation of the workpiece as shown in each figure. Perform boring, face turning, and parting. Now, as mentioned above, in the present invention, which is characterized by cutting chips and smoothing the surface roughness, one further improvement is made to the tool 21. That is, as has been conventionally done, a wiper edge is added to the front cutting edge as shown in FIG. 15. By doing so, the surface roughness is further smoothed, and a cut surface with a smooth surface roughness of about 1 to 2 μm can be obtained. FIG. 18 shows a specific embodiment of the present invention. A workpiece 1 made of carbon tool steel with a diameter of 54 mm and a length of 100 mm is chucked onto the lathe main shaft and rotated at 2200 rpm. Rake angle α=0, side relief angle 25°, nose angle 90
A cutting tool shank 2 in which a cutting edge with a pre-acting cutting edge angle of 20° and a cross cutting edge angle of 70° is glued to the tip of an amplitude expansion horn provided at one end of a vertical ultrasonic electrophoresis transducer 17 with a natural frequency of 21.7 kHz. It is made to vibrate in the direction of arrow 18 at a frequency of 21.7 kHz and a single amplitude of 16 μm. Then, the tightening fitting 2 is placed at two of the vibration nodes that occur in the bite shank 2.
7 to attach this vertical vibration system cutting tool to the tool post 28. Furthermore, the attachment of the heavy vibrator to the tool rest is reinforced by the reinforcing jig 29 by utilizing the vibration node of the amplitude-enlarging horn. In this way, it is possible to obtain a vibrating state in which the cutting edge exhibits regular and stable f and a. Prepare to lubricate this cutting edge with sufficient cutting oil, with a depth of cut of 1 mm and a feed rate of S of 2 μm/rev. Then, a tool rest 30 facing the same carriage is provided, and the tool rest has the same side edge angle,
In this case, a cutting tool 21 having a wiper blade 31 with a length of about 0.5 mm is attached for the purpose of smoothing the surface roughness. And the same cut t
Adjust the blade edge position so that In the examples, the case of carbon tool steel was shown, but the present invention can be applied not only to organic synthetic resin materials such as Teflon and nylon, but also to soft materials such as aluminum alloys and joint alloys as non-ferrous metal materials, and further to carbon steel of iron alloys. The present invention covers not only stainless steel materials and hard materials obtained by hardening them, but also workpiece materials including inorganic materials, which are recent industrial materials. When the workpiece material is hard and brittle, careful attention must be paid to the tool clearance angle. That is, the relief angle is not the relief angle in the triangular waveform approximated in FIG. 5, but the angle H obtained by combining the vibration speed and the cutting speed. When workpiece diameter D, rotation speed n, half amplitude a, and frequency f, H=tan ^-1 2af/D
・The clearance angle is calculated by n. This H is 7 to 10 degrees larger than θ obtained from the approximated triangular waveform.
The mechanical strength of the cutting edge, which is reduced due to this large relief angle, is reinforced by providing a negative rake angle. As described above, the present invention applies vibrations in the ultrasonic range to the cutting tool so that the distance between the workpiece and the cutting tool changes, and cutting is performed intermittently, making chips finer and easier to dispose of. Become. Since cutting is performed intermittently, the temperature rise of the workpiece and the cutting tool can be reduced. This has been proven by the fact that when cutting carbon tool steel as a workpiece, the chips remain white-gray and do not change color due to high temperatures. Furthermore, since the frequency of vibration is extremely high even though it is an intermittent cutting, a sufficient surface roughness can be maintained, and as an example, a surface roughness of 3 to 4 .mu.m and a roundness of 1.5 to 2 .mu.m can be obtained. and,
Since the cutting speed is set above the limit determined by the clearance angle, swing width, and frequency of the cutting tool, the flank surface of the cutting tool does not come into contact with the workpiece. Furthermore, by using a non-vibrating cutting tool in combination with the vibrating cutting tool to intermittently cut the convex portions of the cut surface having irregularities immediately after being formed, it is possible to obtain an even smoother cutting surface. , it is possible to reduce the burden of the vibrating tool.

[Brief explanation of the drawing]

Figures 1 and 2 are side views showing the conventional method;
FIG. 3 is a side view showing the state of cutting by the method of the present invention. Fig. 4 is a side view showing an example of an apparatus for carrying out the method of the present invention, Fig. 5 is an enlarged view showing the cross-sectional shape of the cutting surface, and Figs. 6 to 9 are plan views showing various cutting modes. be. FIGS. 10 to 12 are enlarged sectional views showing cutting conditions when a non-vibrating cutting tool is used, and FIGS. 13 to 18 are plan views showing each embodiment of the present invention. 1... Workpiece, 2... (Vibrating) bite, 1
7... Ultrasonic vibrator, 19, 23, 25... Convex portion, 21... (non-vibrating) bite.

Claims (1)

[Claims] 1. So that the distance between the workpiece and the cutting tool changes,
Apply vibrations in the ultrasonic range to the cutting tool, make the cutting depth (feed amount) of the tooling tool sufficiently smaller than the amplitude of the vibration, and set the cutting speed to the minimum speed determined by the clearance angle, frequency, and amplitude of the tooling tool. A precision high-speed vibration turning method characterized by making the cutting tool larger so that the flank surface of the cutting tool does not come into contact with the workpiece, and cutting intermittently. 2. As the distance between the workpiece and the cutting tool changes,
Apply vibrations in the ultrasonic range to the cutting tool, make the cutting depth (feed amount) of the tooling tool sufficiently smaller than the amplitude of the vibration, and set the cutting speed to the minimum speed determined by the clearance angle, frequency, and amplitude of the tooling tool. The cutting tool is made larger so that the flank surface of the cutting tool does not come into contact with the workpiece, and cutting is performed intermittently. A precision high-speed vibration turning method characterized by intermittently cutting convex portions of a cut surface having minute irregularities immediately after the cutting.