JPS6299062A - Vibration working - Google Patents

Abstract

PURPOSE:To replace the tools having different shape and length by driving a vibration system with the frequency less than the characteristic frequency, in the working method in which a tool which is vibrated in the vertical direction by driving an electric strain vibrator is pressed onto the surface of a workpiece. CONSTITUTION:A vibration system 6 is constituted by integrally jointing a coupling 2 and an electric strain vibrator 3, and a tool 1 is jointed with the coupling 2 in replaceable ways through screw fastening. When the driving frequency less than the characteristic frequency of the vibration system 6 is applied onto the electric strain vibrator 3, any tool vibrates, following to the applied driving frequency, even if the weight of the tool varies, and the amplitude sufficient for the actual use can be obtained. When the vibration system 6 and the tool 1 are prevented from resonate as a whole, as described in the above, a variety of tools can be replaced in a wide range according to the properties of a workpiece and the purpose of working.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibration machining method for machining a workpiece by driving an electrostrictive vibrator to press a vertically vibrating tool against the surface of the workpiece.

[Conventional technology]

Ultrasonic machining is generally known as this type of vibration machining method. Ultrasonic machining is a processing method in which a tool is attached to an amplitude-expanding horn coupled with a vibrator, and the tool is pressed against the workpiece while causing longitudinal vibration resonance as a whole.It is used for drilling, cutting, polishing, engraving, threading, etc. is used to do.

[Problem that the invention seeks to solve]

However, ultrasonic machining has the drawback of severe restrictions on tool exchangeability. The reason for this is that, as mentioned above, ultrasonic machining involves attaching a horn coupled with a vibrator and causing the whole to resonate.In order to obtain such resonance, the tool must be determined by its density and modulus of longitudinal elasticity. Therefore, if the tool is replaced with a tool having a different shape and length than the resonant frequency, resonance will not be obtained and machining will not be possible.

For this reason, only a limited number of types of tools can be used in ultrasonic machining, and when the workpiece has a complex shape, such as a mold, a variety of tools that can handle each part of the shape are required. It is difficult to use, so until now only relatively simple shaped workpieces have been machined with a few tools, with the problem remaining unsolved.

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to eliminate the above-mentioned drawbacks and to provide a vibration machining method that allows the use of various tools depending on the nature of the workpiece and the purpose of machining.

[Means for solving problems]

The present invention uses a vibration machining means comprising a vibration system in which a joint is integrally coupled to an electrostrictive vibrator and a tool exchangeably coupled to the joint, and drives the vibration system at a drive frequency lower than its natural frequency. The present invention relates to a vibration machining method characterized in that a workpiece is machined by vibrating a tool in the vertical direction and pressing the tool against the surface of the workpiece.

If machining is performed in this way, the vibration system is driven at a drive frequency lower than its natural frequency to prevent the vibration system and the tool from resonating as a whole, so different shapes,
The length of the tool can be changed over a wide range depending on the output of the electrostrictive vibrator.

In the present invention, by using a laminated type electrostrictive vibrator, a high vibration frequency and a large amplitude can be obtained, which reduces the load and increases the processing speed, and the amplitude is attenuated by the load. Moreover, it is advantageous because a constant amplitude is obtained regardless of load fluctuations. These effects are due to the multilayer piezoelectric displacement element having a structure in which a plurality of piezoelectric bodies are stacked and displacement is extracted as the sum of the amplitudes of each piezoelectric body.

〔Example 〕

Next, examples of the present invention will be described.

The tools used in this vibration machining method are of various shapes, such as a shank, file, knife, and lap bar, depending on the nature of the workpiece and the purpose of machining. The following will explain the grinding wheel as a representative example. The tool 1 is exchangeably connected to a joint 2 by tightening a screw, and the joint 2 is integrally connected to an electrostrictive vibrator 3, and one end of the electrostrictive vibrator 3 is attached to the inner bottom of a cylindrical protective cover 4 for hand-held use. A small hole 5 that is combined and provided at the tip of the protective cover 4
serves as a guide for the joint 2 inserted therethrough, and the joint 2 and the electrostrictive vibrator 3 constitute a vibration system 6. Reference numeral 7 denotes an oscillator that provides a driving frequency to the electrostrictive vibrator 3.

In this example, a laminated piezoelectric displacement element is used as the electrostrictive vibrator 3, and the tool 1 is vibrated at a frequency of about 50 to 20,000 H2, preferably about 1,000 to 20,000 Hz, and an amplitude of about 5 to 50 microns. It is designed to be granted. Various types of laminated piezoelectric displacement elements can be used, and a typical example is Laminated Piezoelectric Actuator (trade name, manufactured by NEC Corporation). This laminated piezoelectric displacement element was driven by applying a voltage of 100 V DC at Hz, which will be described later.

This drive is performed at a drive frequency lower than the natural frequency of the vibration system 6. The natural frequency of the vibration system 6 can be determined by lightly tapping the entire vibration system 6 with the tool 1 removed in the axial direction and measuring the frequency of minute displacement produced. The natural frequency of the drive system 6 thus determined was 30 KHz.

The weight is 5g due to the displacement operation of the laminated piezoelectric displacement element.
The tool 1 was vibrated in the vertical direction. FIG. 2 shows the respective amplitudes when the driving frequency is different. As shown in Figure 2, the driving frequency is 50.100.300.5
At 00 and 1000Hz, the respective amplitudes are 30.
30, 29, 28 and 25 microns. Even when the driving frequency was changed in this way, the tools 1 vibrated in accordance with the driving frequency, and the amplitude of the tool 1 did not change much.

Next, tools of various weights determined by different shapes and lengths were replaced, and the vibration system 6 was changed to a voltage of 1000H2 DC 130V.
It was driven by The respective amplitudes when the tool has different weights are shown in FIG. As shown in Figure 3, the tool weight is 5.
At 20.35 and 50g, the respective amplitudes are 30.
27.25 and 23 microns. Even when the tool weight changed in this manner, all tools 1 vibrated well following the applied driving frequency, and an amplitude sufficient for practical use was obtained. Then, as shown in Figure 1, the tool 1
When the workpiece was machined by pressing it against the workpiece surface 8, the workpiece could be machined at a satisfactory machining speed in all cases.

Note that when driving with a drive frequency that matches the natural frequency of the vibration system 6, only the vibration system 6 and the tool 1 with the same natural frequency resonate and vibrate, so the vibration system Tool 1, which had a natural frequency different from the natural frequency of tool 6, could not be vibrated. However, according to the above example, since the vibration system is driven at a drive frequency lower than its natural frequency, there are no restrictions on the length or shape of the tool.
A wide range of tools can be used as long as the range corresponds to the output of the laminated piezoelectric displacement element.

〔Effect of the invention 〕

According to the present invention, since the vibration system is driven at a drive frequency lower than its natural frequency to prevent the vibration system and the tool from resonating as a whole, tools of different shapes and lengths can be exchanged over a wide range. be able to. Furthermore, since the displacement of the electrostrictive vibrator can be directly converted into the displacement of the tool, there is an additional effect that the energy transmission efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the vibration machining means used in the method of the present invention, FIG. 2 is a diagram showing the relationship between amplitude and driving frequency, and FIG. 3 is a diagram showing the relationship between amplitude and tool weight. Also, in the symbols used in the drawings, 1 is a tool, 2 is a tool, and 2 is a tool.
is a joint, 3 is an electrostrictive vibrator, 4 is a protective cover, 5 is a small hole,
6 is a vibration system, 7 is an oscillator, and 8 is a workpiece surface. Patent applicant Pilot Mannen Pen Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] Using a vibration machining means comprising a vibration system in which a joint is integrally coupled to an electrostrictive vibrator and a tool exchangeably coupled to the joint, the vibration system is driven at a drive frequency lower than its natural frequency, and the tool is A vibration machining method characterized by machining a workpiece by vibrating the tool in the vertical direction and pressing the tool against the workpiece surface.