JPH01121101A - Cutting tool for ultrasonic vibration cutting device - Google Patents

Abstract

PURPOSE:To improve machining ability by forming a cutting tool fixing member whose thickness becomes thicker as approaching its tip at an end of a cutting tool holder clamped on a flexible vibrator by a clamping body, and locking a cutting tool whose specific gravity is greater than that of the tool holder and whose thickness becomes thicker as approaching its tip of the cutting tool fixing member. CONSTITUTION:When a flexible vibrator 2 is driven, a cutting tool holder 27 clamped by a clamping ring 4 resonantly vibrates vertically in the direction of the arrow centering around a node-position N1 of vibration. At this time, the cutting ability of a threading tool 28 depends on its equivalent mass and vibration amplitude. In this instance, since the thickness of the threading tool 28 of larger specific gravity becomes thicker as approaching its tip, the equivalent mass becomes larger so much, and thus the vibration amplitude also becomes greater. And the thickness of the cutting tool holder 27 becomes thicker as approaching the node N1-position having large vibrating stress, so that its mechanical strength against large vibration stresses is increased. The cutting and machining abilities of the tip 31 of the cutting tool 28 can therefore be greatly increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cutting tool for an ultrasonic vibration cutting device used in lathes, shapers, etc. that cut using ultrasonic vibrations.

BACKGROUND OF THE INVENTION Conventionally, ultrasonic vibrations have been utilized in cutting devices. For example, in a lathe, a cutting tool attached to the output end of a vibrating body that flexibly vibrates is vibrated ultrasonically in the tangential direction of the workpiece, which significantly reduces cutting resistance and improves machining accuracy. It is known that significant vibration cutting effects can be obtained, such as improved vibration.

As for the above-mentioned ultrasonic vibration cutting device, patent applications have been filed by the present applicant as "Japanese Patent Application No. 62-24047", "Japanese Patent Application No. 116187-1987", and "Japanese Patent Application No. 124-721-1984". ing. Therefore, the flexible vibrating body commonly used in these devices will be explained based on FIGS. 5 to 11.

The deflection vibrator 1 includes a deflection vibrator 2, a cutting tool 3, and a fastening ring 4 as a fastening body.

A metal material 5 is attached to the deflection vibrator 2 from both sides at the large diameter part.
, 6 and polarized in the thickness direction, the electrodes 9 and 10 divided into two are opposed to each other, and are provided with two electrode plates 11 and 12 interposed therebetween. It is being Further, an annular insulating tube 13 is inserted into the inner periphery of the electrostrictive elements 7 and 8, and a common electrode plate 14 is provided between the front electromotive strain element 8 and the metal material 6. Further, a right-handed thread 16 is formed at the tip of the output end 15 of the deflection vibrator 2. The deflection vibrator 2 constructed in this way is integrated by screwing and tightening a bolt 18 into a screw hole 17 formed in the end side surface of the metal material 5.

The cutting tool 3 includes a cutting tool holder 19 and a cutting tool 20. The tool holder 20 has the tool 20 fixed to one end with silver solder or the like, and a left-hand thread 21 is formed at the other end on the opposite side, and the left-hand thread 21 and the deflection vibration Output end 15 of child 2
The right-hand thread 16 formed in the vibration loop portion L□
By positioning it at and tightening it with the tightening ring 4,
It has an integrated structure as a deflection vibrator 1.

The flexible vibrating body 1 integrated in this way has conical recesses 22 and 23 formed on the side surfaces of the large diameter portion located at the vibration node portions N, , N, and is provided with sharp edges (not shown) from four locations on both sides. It is fixed by making strong contact with the tip bolt. In this state, with the common electrode plate 14 as a reference, driving voltages with opposite phases to each other are applied to the two electrode plates 11 and 12 to adjust the frequency to the flexural resonance frequency, and the flexural vibrator 1 moves to the sixth Resonant vibration is performed by drawing a trajectory of vibration amplitude as shown in Figure (b).

As a result, the cutting edge of the cutting tool 20 fixed to the tip of the cutting tool holder 19 strongly vibrates in a direction perpendicular to the axis of the flexible vibrating body 1, as shown by the arrow.
When the cutting edge of the blade is cut into a workpiece (not shown), cutting can be performed with the vibration cutting effect as described above.

Problems to be Solved by the Invention However, the cutting ability of the flexible vibrating body 1 as described above is determined by the magnitude of vibrational energy possessed by the cutting edge of the cutting tool 20.

Generally, when the mass of an object is m and its velocity is V, the kinetic energy E of the object is expressed as E=mv2/2 (1).

Further, when the vibration speed of the cutting edge of the cutting tool 2o vibrating under the conditions of equation (1) is V, the vibration frequency is f, and the vibration amplitude is a, the following relationship is established: v=2πfa (2).

Therefore, from these equations (1) and (2), the cutting ability of the cutting edge of the cutting tool 20, that is, the vibration cutting energy is:
Assuming that the vibration frequency is constant, it is determined by the magnitude of the mass m and the vibration amplitude a.

Therefore, in order to increase the cutting ability of the conventional bending vibrator 1, the following steps are taken. First, in order to increase the vibration amplitude a, the diameter ratio of the two step portions 24 and 25 of the flexible vibrating body 1 is further increased. This allows the vibration amplitude a to be greatly expanded, but in this case, increasing the diameter ratio also reduces the equivalent mass m of the cutting edge. As a result, there will naturally be a limit to the cutting ability of the cutting edge of the cutting tool 20.

Next, in order to increase the mass m of the cutting edge, the width W of the cutting tool 20 is made wider, as shown in FIG.

As a result, the equivalent mass m can be increased, but in this case, in the case of a tool with an acutely pointed cutting edge, such as a thread cutting tool (not shown), the equivalent mass m can be increased by increasing the width W. It is not expected that the mass m will increase much, and as a result, the effective cutting ability of the cutting edge of the cutting tool 20 will hardly increase.

In addition, as shown in FIG. 8, the wall thickness t1 of the cutting tool 20 made of carbide material with high specific gravity is increased, and the wall thickness t2 of the tool holder 19 at the fixed portion of the tool 20 is made thinner. However, in this case, conversely, the tool holder 1
This means that by reducing the thickness of 9, fatigue will occur due to vibration stress.

Means for Solving the Problems In order to solve these problems, a tool fixing part is attached to one end of the tool holder, which is fastened to the flexible vibrator by a clamping body, and the wall thickness becomes thinner as it approaches the tip. A cutting tool having a specific gravity larger than that of the cutting tool holder and increasing in thickness as it approaches the tip was fixed to this tool fixing part.

Effect: Therefore, the closer you get to the tip of the tool fixing part of the tool holder, the larger the proportion of the tool with higher specific gravity will be.
The equivalent mass of the cutting edge of the cutting tool for ultrasonic vibration increases,
In addition, since the wall thickness of the bit fixing part becomes thicker as it approaches the base on the opposite side from the tip, the mechanical strength of the bit fixing part against vibration stress increases. Cutting ability can be further improved.

Embodiment A first embodiment of the present invention is shown in FIGS. 1 and 2 (a) and (b).
). The flexible vibrator 1 is composed of a flexible vibrator 2, a cutting tool 26, and a fastening ring 4 as a fastening body. In addition, here, the cutting tool 2
6 will be mainly explained, and explanations of other parts that are the same as those of the prior art will be omitted.

The cutting tool 26 includes a cutting tool holder 27 and a thread cutting tool 28 as a cutting tool.

This cutting tool holder 27 is formed into a step shape with an R step part 29 at the vibration node portion N1, and a cutting tool fixing part 30 is formed at the tip thereof, which has a diagonal shape and becomes thinner as it approaches the tip. ing. In addition,
As the tool holder 27, tool steel such as SK steel or 80M steel is used in consideration of mechanical strength and fatigue limit against vibration stress.

The thread cutting tool 28 has a shape opposite to that of the tool fixing part 30, and the wall thickness becomes thicker as it approaches the tip. Further, a cutting edge 31 and a rake portion 32 are ground on the upper surface of the thread cutting tool 28. The thread cutting tool 28 is fixed to the tool holder 27 through the tool 1 to the fixing section 30 by silver soldering or the like.

Note that, as the cutting tool, a carbide material having a higher specific gravity and greater hardness than the cutting tool holder 27 is used.

Further, while the tool steel used for the tool holder 27 has a specific gravity of 8, the specific gravity of the cemented carbide used for the thread cutting tool 28 is 12, which is about 1.5 times as large.

In such a configuration, when the deflection vibrator 2 is driven as explained in the prior art, the tool holder 27 tightened by the tightening ring 4 is moved as shown in FIG. 2(b).
Centering around the vibration node portion N□, resonance vibration occurs in the vertical direction as shown by the arrow.

At this time, it is known that the cutting ability of the cutting edge 31 of the thread cutting tool 28 is determined by the equivalent mass m and the vibration amplitude a from the above-mentioned equations (1) and (2).

In this case, since the wall thickness of the thread cutting tool 28, which has a higher specific gravity, increases toward the tip, its total equivalent mass m increases, and as a result, the vibration amplitude also increases.

In addition, the tool holder 27 is connected to the node N1, which has a large vibration stress.
Since the wall thickness becomes thicker as the position approaches , the mechanical strength increases against a large vibration stress as shown by the broken line in FIG. 2(b).

Therefore, the cutting ability of the cutting edge 31 of the thread cutting tool 28 is greatly increased by increasing the equivalent mass m and the vibration amplitude a.

Next, a second embodiment of the present invention is shown in FIGS. 3 and 4 (a).
) (b).

The cutting tool 33 includes a cutting tool holder 34 and a single-edged cutting tool 35 as a cutting tool.

The tool holder 34, like the tool holder 27,
The vibration node portion N1 is formed into a step shape with an R step portion 36, and a cutting tool fixing portion 37 whose wall thickness becomes thinner as it approaches the tip is formed.

The single-edged cutting tool 35 has a shape opposite to that of the cutting tool fixing part 37, and the wall thickness increases as it approaches the tip. Further, a cutting edge 38 and a rake portion 39 are ground on the upper surface of the single-edged cutting tool 35. The single-edged cutting tool 35 is fixed to the cutting tool fixing portion 37 of the cutting tool holder 34 by silver soldering or the like.

In such a configuration, the cutting ability of the cutting edge 38 of the single-edged cutting tool 35 is the same as that in the first embodiment, so a description thereof will be omitted here.

Next, a first experimental example will be explained. First, consider a case where a thread cutting tool is used as the conventional tool 20 as shown in FIG. Now, a diameter 18
Bit holder 19 with rounded step part with thickness of 8 mm
are tightly fastened with a fastening ring 4 to constitute a flexible vibrating body 1. In addition, as a thread cutting tool, carbide material KIO
, thickness 4 mm, length 13.5+n+n.

When such a flexible vibrating body 1 is connected to an ultrasonic oscillator and driven, the resonance frequency becomes 19.6 kHz and the amplitude becomes 15 μm when the input power is 12 W in the air. In this case, when the workpiece (not shown) was made of SK3 steel with a diameter of 40 mm and the workpiece was machined with a screw pitch of 1 mm, the workpiece was machined in four steps, and the maximum input power to the deflection oscillator at that time was 64W.

On the other hand, an experiment was conducted by replacing the tool holder 27 with a shape as shown in the first embodiment of the present invention as shown in FIG. The thread cutting tool 28 is made of carbide material KIO as in the conventional example.
The thickness was 5 mm at the thicker end, 2 mm at the thinner end, and 12.5 mm long, and the combined thickness with the bite holder 27 was 9 mm.

When such a flexible vibrating body 1 is connected to an ultrasonic oscillator and driven, the resonance frequency becomes 18.6kl (z, amplitude 18μm) when the input power is 10W in the air.In this case, the workpiece (not shown) When processing the above-mentioned SK3 steel with a thread pitch of 1+nm, it could be processed at least twice compared to the conventional example, and the input power to the deflection vibrator at this time was 105 W at maximum.

Next, a second experimental example will be explained. First, consider the case where a single-edged cutting tool is used as the conventional cutting tool 20 as shown in FIG. As in the first experimental example, a tool holder 19 having an rounded step with a diameter of 18 m+++ and a thickness of 8 mm is tightly fastened to the output end of the flexible vibrator 2 with a diameter of 45 mm by the tightening ring 4, and the bending vibration is generated. constitutes body 1. Also, as a single-edged tool, 10. Thickness 4mm,
The length shall be 7.5 mm.

When such a flexible vibrator 1 is driven by an ultrasonic oscillator, the resonance frequency is 19.2 with an input power of 10 W in the air.
The frequency was kHz and the amplitude was 15 μm. In this case, when cutting the outer circumference of SK3 steel as a workpiece, when the feed was set to 0.09 mm/rev, vibration cutting could be performed well up to a depth of cut of 1.6 mm.

The input power to the flexural oscillator at that time was 64W.

On the other hand, an experiment was conducted by replacing the tool holder 34 with a shape shown in the second embodiment of the present invention as shown in FIG. The single-edged cutting tool 35 is made of carbide material KIO as in the conventional example, and has a thickness of 611II at the thick tip, 2 mm at the other thin end, and 8.2 mm in length.

When such a flexible vibrator 1 is connected to an ultrasonic oscillator and driven, the resonance frequency becomes 18.3 kl (z, amplitude 17 μm) when the input power is 10 W in the air. In this case,
Cutting the outer circumference of 5K3fi as a workpiece 0,09
When I used mm/rev feed, it was 2,4 mm.
Vibration cutting could be performed satisfactorily with a depth of cut up to 86 W.

As described above, in all of the experimental examples, the cutting tool 28,35 of the present invention had a larger vibration amplitude due to an increase in equivalent mass and a significantly larger maximum cutting depth than the conventional cutting tool 20.

Effects of the Invention The present invention forms a cutting tool fixing part whose wall thickness becomes thinner as it approaches the tip at one end of a cutting tool holder that is fastened to a deflection vibrator by a fastening body, and the cutting tool fixing part is provided with a part that is thinner than the cutting tool holder. Since we have fixed a tool that has a large specific gravity and becomes thicker as it approaches the tip, the percentage of the tool that has a larger specific gravity increases as you get closer to the tip of the tool fixing part of the tool holder. As the equivalent mass increases and the wall thickness of the tool fixing part increases as it approaches the base opposite to the tip, the mechanical strength of the tool fixing part against vibration stress increases. Therefore, the cutting ability of the cutting edge of the cutting tool can be further improved.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the first embodiment of the present invention, Fig. 2 is a side view showing its vibration amplitude and vibration stress, and Fig. 3 is a side view showing the first embodiment of the present invention.
Figure 4 is a plan view showing the second embodiment of the present invention, Figure 4 is a side view showing its vibration amplitude and vibration stress, Figure 5 is a perspective view showing the conventional example, and Figure 6 is its vibration amplitude. Fig. 7 is a plan view of the tool holder part wider than Fig. 5, Fig. 8 is a side view of the tool holder part shown in Fig. 7, and Fig. 9 is a plan view of the tool holder part shown in Fig. A perspective view of the tool holder part,
FIG. 10 is a perspective view of the electrostrictive element, and FIG. 11 is a perspective view of the electrode plate. 2... Flexural vibrator, 4... Clamping ring (clamping body)
, 27...Bite holder, 28...Bite, 30.
...Bite fixing part, 34...Bite holder, 35...
・Part-time job, 37...Part-time job fixed department application Person: Taga Electric Co., Ltd. Tadaku L! Σ Zu I2x
Door-＼0”ko＋＋＋／
N1〆zu -○ 店 -Q 61'' wO diagram JJA diagram A!

Claims (1)

[Claims] A cutting tool fixing part is formed at one end of the cutting tool holder which is fastened to the deflection vibrator by a fastening body, and the wall thickness becomes thinner as it approaches the tip, and this cutting tool fixing part has a larger specific gravity than the cutting tool holder and approaches the tip. A cutting tool for an ultrasonic vibration cutting device, which is characterized by a fixed cutting tool whose wall thickness increases as the wall thickness increases.