JPH07156046A - Vibration grinder - Google Patents

Abstract

PURPOSE:To enable simple vibration grinding to be carried out by arranging a rotary member having a magnetized body which is at least partially piled on the end surface of a bar magnet and magnetized equivalently to the magnetic pole of the bar magnet. CONSTITUTION:A super magneto strictive alloy 1 is assembled in a rotary shaft 2 together with a magnet 11 for bias. A rotationally driving plate 4 for making rotational drive is installed on the end surface of this rotary shaft 2 and the rotary shaft 2 is rotatably driven by a motor and a pulley provided outside. The rotary shaft 2 is supported by bearings 5, 6 provided in a space toward a case P and especially, the movement of the rotary shaft 2 in an axial direction is not limited by the bearing 6 on a grinding wheel 7 side. A grinding wheel 7 is installed on the tip of the rotary shaft 2 and vibrates synchronizing with the rotation of the rotary shaft 2. A permanent magnet 3 is installed on the periphery of the super magneto-strictive alloy 1 and sandwiched by a magnetized body 12 from both end surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration grinding device for hard and brittle materials, metal materials, plastic materials, etc., or teeth used in dentistry.

[0002]

2. Description of the Related Art In the processing of metal materials, a shape is created by cutting, and grinding is performed when higher shape accuracy is required. Further, also in the processing of hard and brittle materials, grinding is performed after sintering to improve surface roughness and dimensional accuracy. Further, in the processing of glass, which is a kind of hard and brittle material, a grinding process is performed to create a shape, and particularly in the processing of a lens, a grinding process is used for the shape creation as a pre-polishing step. In this way, in the removal processing of metal materials and hard and brittle materials,
Most parts that require high accuracy are generally ground.

In the above-described grinding method, generally, a grindstone is rotated at a high speed, the peripheral speed is set to about 1800 m / min, and the grinding wheel is brought into contact with the surface of a workpiece and moved to continuously perform the removal processing. The cut amount at that time is from several μm to several tens μm. Further, since a tooth grinding machine is often held by a dentist and works in the mouth, it is a compact and lightweight grinding machine. In addition, since the workpiece is a tooth, a small-diameter grindstone is often used, and it is necessary to increase the rotational speed of the grindstone to obtain a sufficient grinding speed for that purpose. Drives the grindstone shaft and is used for treatment.

For the normal grinding process as described above,
Further, as an attempt to improve the processing performance, there is a vibration grinding method in which a grinding wheel is vibrated to perform processing. The vibration frequency when vibrating the grindstone ranges from low-frequency vibration of several tens of Hz to several tens of kHz.
Ultrasonic vibration has been tried, but the common effect of this processing method is that the processing efficiency is dramatically improved.

Generally, in the above vibration grinding, an electrostrictive or magnetostrictive ultrasonic vibrator is often used as a means for vibrating the grindstone in the ultrasonic range. Further, as a method of vibrating the grindstone at a low frequency, there are a method using an electric motor and an electromagnetic vibrator, a method using hydraulic pressure and the like. Furthermore, recently, a giant magnetostrictive alloy capable of taking out an extremely large strain has been commercialized. This alloy can generate a much larger strain than the conventional magnetostrictive material when a magnet is applied from the outside, so that the magnetic generation means by the supermagnetostrictive alloy 1 and the coil 13 having the structure shown in FIG. 4 is incorporated. A vibration grinding machine has also been proposed.

[0006]

In the grinding process, it is necessary to rotate the grindstone shaft at a high speed so that the grindstone has a certain peripheral speed. Therefore, when an ordinary electric motor is used, the number of revolutions and the output are limited, so that the diameter of the grindstone is restricted. In other words, in order to secure the peripheral speed of the grindstone necessary for the grinding process, a certain grindstone diameter is required unless the rotational speed of the grindstone can be significantly increased. Formula (1) shows the relationship between the diameter of the grindstone, the number of revolutions, and the grinding speed.

V = (πDN) / 1000 (1) N; number of revolutions of the grindstone (rpm) D; diameter of the grindstone (mm) V; peripheral speed of the grindstone (m / min) (grinding speed) For example If the diameter of the grindstone is 250 mm when trying to obtain a grinding speed of 1800 (m / min),
The required number of rotations of the spindle is about 2300 rpm, but at the same grinding speed, if the diameter of the grindstone is 3 mm, the number of rotations required for the spindle will be 190,000 or more.
Achieving this rotation speed as a main axis of a grinding machine using an ordinary electric motor requires a high level of technical skill, and the machine becomes large in scale, which cannot be easily realized.

Therefore, in a grinding apparatus used for teeth which has a low grinding resistance and does not require a large amount of power, a method of increasing the rotational speed of a grindstone using an air turbine is generally used. However, since the grindstone is rotated at a high speed for machining, the grindstone is clogged, and when the sharpness is poor, heat is likely to be generated in the machined part.

On the other hand, in the vibration grinding process described in the preceding paragraph, since the high grinding performance is exhibited even in the region where the grinding speed is relatively low, the grinding can be performed without increasing the rotational speed of the grindstone. Therefore, less heat is generated during processing. Further, the clogging of the grindstone is unlikely to occur. However, there is a problem in that a mechanism for vibrating while rotating the grindstone attached to the rotary shaft is required, and the device becomes large-scale.

Further, in the vibration grinding method using the giant magnetostriction described in the preceding paragraph, the magnetic coil for driving the giant magnetostriction is required, and the oscillator for driving this coil and the code for transmitting the drive current are required. In addition, there was also the problem of fever. The object of the present invention is to solve these problems.

[0011]

[Means for Solving the Problem] In order to solve the above-mentioned problems, as a result of intensive research, "in a vibration grinding machine having a grindstone attached to the tip of the rotating shaft A: a rotating shaft having a super magnetostrictive alloy incorporated therein, B: A magnetic circuit in which two or more bar magnets are arranged in parallel with the rotary shaft and around the rotary shaft so that the magnetic poles of the adjacent bar magnets are opposite to each other, and C: the magnetic circuit is sandwiched from the axial direction. A rotary member attached to the rotary shaft, the rotary member having at least two magnetized bodies at least partially overlapping the end surface of the bar magnet and having a magnetism corresponding to the magnetic poles of the bar magnet; It has been found that the above problems can be solved by providing a vibration grinding device characterized by having a rotating means for rotating the rotary shaft.

[0012]

In order to realize the vibration grinding, it is necessary to vibrate the abrasive grains on the surface of the grindstone in the radial direction, the axial direction, and the rotating direction (the state in which the rotation of the shaft and the displacement caused by the vibration are superimposed) with respect to the rotating shaft. . By the way, currently available giant magnetostrictive alloys generate strain in the longitudinal direction with respect to an external magnetic field, so by incorporating this giant magnetostrictive alloy, vibrations in the axial direction with respect to the grindstone rotating shaft are generated. It is possible to configure a vibration grinding device that generates the vibration.

Further, in order to vibrate the grindstone in the longitudinal direction of the rotating shaft, it is necessary to apply an alternating magnetic field to the giant magnetostrictive alloy. Therefore, a rod-shaped permanent magnet is provided in a position parallel and symmetrical to the giant magnetostrictive alloy, and a magnetized body that moves together with the rotating shaft is provided at a position corresponding to the end face of the permanent magnet so that the rotating shaft rotates in synchronization with it. As a result, the grindstone attached to the tip of the rotary shaft vibrates in the axial direction.

The vibration amplitude of the grindstone depends on the type of giant magnetostrictive alloy and the strength of the magnetic field generated by an external permanent magnet.
The frequency of the grindstone depends on the number of permanent magnets installed outside. Expression (2) shows the relationship between the number of permanent magnets, the rotational speed of the grindstone shaft, and the vibration frequency of the grindstone.

F = (Nn) / 60 (2) N: Number of revolutions of the grindstone shaft (rpm) n; Number of sets of permanent magnets of opposite polarity (set) F; Vibration frequency of the whetstone (Hz) ( If N = 300 (rpm) and n = 4 (set) from the equation (2), the vibration frequency F of the grindstone becomes F = 20 (Hz).

As described above, in the vibration grinding apparatus according to the present invention, by combining the giant magnetostrictive alloy and the permanent magnet, the vibration grinding processing can be realized with an extremely simple apparatus. Hereinafter, the present invention will be described more specifically by way of examples with reference to the drawings, but the present invention is not limited thereto.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a vibration grinding apparatus according to the present invention. The giant magnetostrictive alloy 1 is incorporated in the rotating shaft 2 together with the bias magnet 11. A rotary drive pulley 4 for rotationally driving the rotary shaft 2 is provided on the end surface of the rotary shaft 2.
The rotating shaft 2 is rotationally driven by an electric motor and a pulley provided outside. The rotating shaft is a bearing 5 provided between the rotating shaft and the case 9,
It is supported by 6 and in particular the bearing 6 on the grinding wheel side does not limit the axial movement of the rotary shaft 2. A grindstone 7 is attached to the tip of the rotary shaft 2 and vibrates (vibration direction 8) in synchronization with the rotation of the rotary shaft 2. The permanent magnet 3 is installed on the outer periphery of the giant magnetostrictive alloy 1 and is sandwiched by the magnetized body 12 from both end surfaces.

FIG. 2 is an enlarged view of the permanent magnet portion.
In the embodiment, the permanent magnet 3 is a cylindrical magnet in which S and N are alternately arranged. FIG. 3 is a principle view seen from the end face direction of the permanent magnet for explaining that in the embodiment, it was possible to apply an SN alternating magnetic field to the giant magnetostrictive alloy by rotating the rotating shaft. is there. A magnetized body 12 is provided on a portion of the rotary shaft 2 corresponding to the end face of the permanent magnet 3. The width of the magnetized body is substantially equal to the width of the magnetic pole of the permanent magnet 3, and the rotation of the rotating shaft 2 causes the magnetized body 1 to rotate.
2 alternately passes through the S poles and the N poles of the end face of the permanent magnet 3, thereby applying an alternating magnetic field to the giant magnetostrictive alloy.

In this embodiment, the giant magnetostrictive alloy that can generate strain in the longitudinal direction is used. However, the same driving method can be performed by using a giant magnetostrictive alloy that generates strain in the rotational direction and the bending direction. Is.

[0020]

By performing the vibration grinding process by the method shown in the embodiment of the present invention, the vibration grinding process can be realized by an extremely simple method. As a result, compared to conventional grinding, it prevents clogging of the whetstone, reduces the number of times the whetstone is dressed, and does not require high-speed rotation, so there is no need to be nervous about the dynamic balance of the whetstone, and work efficiency is improved. Is improved. Further, the grindability is improved, and the heat generated during processing is reduced.

Further, when it is used for teeth, the heat generated during processing is reduced and the burden on the patient is reduced. Further, in the embodiment, there is no electric supply from the outside (only the rotating force from the outside is supplied from the rotating pulley), so there is no danger of electric shock even if the device is put in the mouth, and it is safe. Is.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a vibration grinding apparatus using a giant magnetostrictive alloy according to an embodiment of the present invention.

2 is a partially enlarged view of the apparatus shown in FIG.

FIG. 3 is a schematic diagram showing the principle of the present invention.

FIG. 4 is a schematic diagram of a conventional vibration grinding apparatus using a giant magnetostrictive alloy.

[Explanation of Codes] 1 ・ ・ ・ Giant magnetostrictive alloy 2 ・ ・ ・ Rotary shaft 3 ・ ・ ・ Permanent magnet (bar magnet) 4 ・ ・ ・ Rotation drive pulley 5 ・ ・ ・ Bearing 6 ・ ・ ・ Bearing 7 ・ ・ ・Grinding stone 8 ・ ・ ・ Vibration direction 9 ・ ・ ・ Case 11 ・ ・ ・ Bias magnet 12 ・ ・ ・ Magnetic body 13 ・ ・ ・ Coil

Claims (1)

[Claims] 1. A vibration grinding apparatus having a grindstone attached to the tip of a rotating shaft, wherein A: a rotating shaft having a giant magnetostrictive alloy incorporated therein, and B: two or more bar magnets parallel to and adjacent to the rotating shaft. A magnetic circuit arranged around the rotating shaft so that the magnetic poles are opposite to the bar magnet; C: a rotating member attached to the rotating shaft so as to sandwich the magnetic circuit from the axial direction, A rotary member having at least two magnetized bodies which at least partially overlap with the end face of the bar magnet and have a magnetism corresponding to the magnetic poles of the bar magnet; and D: a rotating means for rotating the rotary shaft. Vibration grinding equipment.