JPS6147642B2 - - Google Patents

Description

[Detailed description of the invention]

Recent lathes have improved in structure and function, and are now capable of high-speed cutting. This high-speed cutting is extremely effective for improving machinability and cutting efficiency. However, on the other hand, the current situation is that it is very difficult to deal with continuous high-temperature chips. There is a desire to divide these continuous chips to make them easier to process, and the present invention
The purpose is to meet this demand. In order to achieve the above object, the present inventor made a separate invention and filed an application on the same date as the present application. The invention of this separate application vibrates ultrasonically the cutting edge of a cutting tool with a clearance angle condition in the direction of its back force.
Plastics can be cut by cutting at a high cutting speed of m/min or higher, by setting the feed (depth of cut) to a very small feed rate of about 1/50 of the amplitude (half amplitude), and by applying sufficient cutting fluid. All industrial materials, from wood to carbon steel and even inorganic materials, can be shredded into needle-shaped chips using conventional turning processing without adversely affecting shape accuracy such as roundness. It can be precisely turned with precision. The invention of the separate application involves ultrasonic vibration of the cutting tool, but it is clear that the same result can be obtained even if the workpiece is ultrasonically vibrated. In addition, there is no need to attach an ultrasonic excitation device to each cutting tool. The present invention is based on the above idea, and devises a method for applying ultrasonic vibration to a workpiece. The invention of the separate application is based on the direction in which the distance between the cutting tool and the workpiece changes (backward force direction).
Since the cutting tool is vibrated ultrasonically, in order to apply the same relative vibration to the workpiece, the workpiece must be vibrated in the direction toward the cutting tool. but,
This is not an easy task since the workpiece is chucked at one end and is rotating. In order to achieve this, it is not possible to obtain the desired vibration even if the ultrasonic vibrator is directly attached to the workpiece, and even if it becomes possible in the future, the vibrator can be attached and detached one by one to the workpiece. Therefore, it is not suitable for mass production processing. The present invention solves the above problems and is characterized in that ultrasonic vibrations are applied to a rotating workpiece from a fixed portion via cutting oil. Next, the present invention will be explained in detail with reference to illustrated embodiments. The workpiece 1 is chucked to the chuck 2, and the tip face of the amplitude amplifying horn 4, which amplifies the amplitude of the ultrasonic longitudinal vibrator 3, has the maximum amplitude on the cutting part as shown in FIGS. 1 and 2. and place them close together and facing each other. A large amount of cutting oil 6 is supplied from a cutting oil supply pipe 5 to the space between the workpiece 1 and the tip of the horn 4. When the ultrasonic longitudinal vibrator 3 is excited, the horn 4
The tip vibrates ultrasonically in the direction of arrow 10 with frequency f and amplitude a. The vibration energy is then transmitted to the workpiece 1 via the cutting fluid 6. The workpiece 1 is checked in a state where it bends and vibrates with a frequency f and a bending ultrasonic vibration mode of first order, . . . n order. FIG. 1 shows a case in which the device vibrates in a first-order bending vibration mode with one end fixed and the other end free, and its natural frequency is f. According to the present invention, the workpiece can be rotated in the direction of the arrow 11 while being subjected to bending vibration. This workpiece is cut at high speed by applying a cross feed S in the direction of an arrow 13 to a cutting tool 7 fixed to a lathe tool rest 8 with a bolt 9. By doing this, a group of shredded chips 12 as shown in FIG.
is generated. In order to rotate the workpiece 1 at a high rotational speed of 1000 rpm or more, the cutting fluid 6 is easily dispersed, so when the rotational direction of the workpiece 1 is as shown in FIG. Supply oil at a sufficient flow rate. The cutting point position P where the workpiece 1 and the cutting edge of the cutting tool 7 are in contact changes with a sinusoidal waveform depending on the vibration speed due to the frequency f and amplitude a of the workpiece 1 and the cutting speed v. FIG. 3 shows the cutting surface when this sine waveform is approximated and considered as a triangular waveform. In other words, consider it as a triangular waveform surface abcdefg... When the workpiece rotates once and the cutting tool tip p advances at the feed rate Smm, the cutting surface becomes a triangular waveform surface a′b′c′d′e′f′g′
……
becomes. Then, with the rake face of the cutting tool 7, each of the small blocks bcc'b', dee'd', fgg'f'... indicated by diagonal lines are cut intermittently and the cutting process is continued while generating fragmented chips. . This cutting tool 7 is given a clearance angle θ which is larger than the inclination angle H of the triangular waveform surface shown in the figure. By providing this clearance angle θ, it is possible to perform smooth chip-shredding high-speed vibration cutting without the cutting tool flank surface coming into contact with the triangular waveform surface abcdefg. That is, in triangle h′j′d′

[Formula] That is, H= tan ^-1 gives a clearance angle of 4af/v or more. In addition, if the workpiece is made of a hard material, it is possible to give a clearance angle that is greater than the maximum inclination angle H' of the sinusoidal waveform that is a composite of the velocities drawn by the motion locus of the cutting point position of the workpiece, so that the cutting tool flank surface can be cut even momentarily. It is important to cut the material so that it does not come into contact with the cutting surface. Furthermore, the ultrasonic longitudinal transducer 3 fixed on the lathe carriage by the chuck method as shown in FIG.
and the amplitude amplifying horn 4, the ultrasonic vibration energy is applied to the rotating workpiece 1,
The workpiece 1 can be cut by uniformly ultrasonically vibrating each point of the workpiece in the same phase in the radial direction. In other words, the workpiece 1 is set to the natural frequency f of the vibrator 3.
A chuck is applied to the chuck 2 via the elastic body 15 so that the natural frequency _fo is lower than that of the chuck 2. In this way, the workpiece 1 undergoes ultrasonic vibration in the direction of the arrow 11 with the frequency f and the amplitude a due to the ultrasonic vibration energy given through the cutting oil 6 supplied in large quantities from the oil supply pipe 5. do. This workpiece 1
is rotated at high speed, and the cutting tool 7 fixed to the tool rest 8 with bolts 9 is fed vertically to perform turning on the cylindrical surface. At this time, the cutting tool used has a nose radius R
Use a round-tipped cutting tool. The side relief angle and the front relief angle of this round tip cutting tool 7 are finished to be the same. This clearance angle H or H' is given by the calculation method described above. The workpiece vibration system at this time is modeled and expressed as shown in FIG.
Considered as a one-degree-of-freedom oscillating system with a spring constant k and a dart pot c, the regular a sin
The workpiece 1 vibrates in its radial direction with a vibration state of (2πf·t). Then, the cutting mechanism shown in FIG. 3 is satisfied, chips are shredded, the cutting force also becomes a pulsed cutting force waveform, and the cutting force acting on the workpiece and the cutting tool is reduced. In the present invention, it is necessary to perform cutting under cutting conditions that provide cutting energy smaller than the applied vibration energy. Therefore, light cutting is generally performed. Next, an example of implementation data of the present invention will be shown. A stainless steel workpiece with a diameter of 10 mm and a length of 10 mm was checked on the lathe main shaft through a hard rubber collector chuck with an overhang of 5 mm, and this was carried out at 6800 rpm.
Rotate with high speed rotation, horn tip diameter 10
mm horns are set with a gap of approximately 1 mm, and the ultrasonic vibrator is vibrated ultrasonically at a frequency of 21.7 kHz and a high output of 2 kW, and a large amount of mixed oil of spindle oil and machine oil is supplied. At the same time, using a carbide cutting tool with a relief angle of 20° and a tip nose radius of 0.5 mm,
As a result of vibration cutting the outer circumference of the cylinder at a cutting speed of 214 m/min under the cutting conditions of feed rate 0.3 μm/rev and depth of cut 0.2 mm,
Finely shreds chips with roundness of 1 to 1.5μ
Turning was successfully performed with a surface roughness of 1 to 1.5 μm Rmax. As described above, the present invention vibrates the workpiece ultrasonically and cuts intermittently at that frequency, making the chips finer and easier to dispose of. Since this discontinuation is performed at extremely high speed, the surface roughness of the finished surface will not be deteriorated. Furthermore, since the workpiece is vibrated, even when switching cutting tools, only one ultrasonic excitation device needs to be installed, and the vibrations are transmitted to the workpiece via cutting oil. , the ultrasonic excitation device can be fixedly arranged.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of an apparatus for implementing the method of the present invention, FIG. 2 is a front view of the same, and FIG. 3 is an enlarged front view of a cutting surface. FIG. 4 is a plan view of another apparatus for carrying out the method of the present invention, and FIG. 5 is a front view of the same. 1...Workpiece, 2...Chuck, 3...Ultrasonic longitudinal vibrator, 4...Horn, 6...Cutting oil, 7...
Bit, 12...Chip, 15...Elastic body, θ
...Escape angle.

Claims (1)

[Scope of Claims] 1. A method for cutting a workpiece that is chucked at one end and that rotates at high speed with a cutting tool that is pressed against the workpiece so as to generate at least a component force in the radial direction of the rotation. An ultrasonic excitation device is fixed to a fixed part, which is placed facing the workpiece in a radial direction with a gap therebetween, and cutting oil is supplied to the gap, so that ultrasonic vibrations are transmitted to the workpiece through the cutting oil. A precision high-speed vibration turning method characterized in that the cutting is performed intermittently by the ultrasonic vibration. 2. The precision high-speed vibration turning method according to claim 1, characterized in that the natural frequency of the chucked workpiece is caused to resonate with the vibration of an ultrasonic excitation device. 3. The precision high-speed vibration turning method according to claim 1, characterized in that the chuck is performed via a fixture so that the natural frequency of the chucked workpiece is lower than the frequency of the ultrasonic excitation device. . 4 Claims 1 to 3, characterized in that the relief angle of the cutting tool is tan ^-1 4af/v or more (where a is the amplitude, f is the frequency, and v is the cutting speed) Precision high speed vibration turning method described.