JPH08257896A - Manufacture of polishing article and vibration magnetic polishing work device - Google Patents

Abstract

PURPOSE: To high efficiently polish a polishing article by polishing a workpiece while applying an alternating magnetic field to a magnetic abrasive material. CONSTITUTION: A coil 2 is wound to a magnetic circuit 1, and a current superimposed with a bias current and an alternating current together, flows in this coil 2. A gap is provided partially in this magnetic circuit 1, here to insert a workpiece (for instance, cylindrical member) 3 rotated with its axis serving as the center. A magnetic abrasive material 4 is held between this workpiece 3 and a magnetic pole in an end face of the magnetic circuit 1. Crushing ferrite into powder is used in this magnetic abrasive material 4, and a ferrite-made transformer core is used in the magnetic circuit 1. A DC current, in a condition superimposed with an AC current of about 10Hz, is applied to this magnetic circuit 1, and by performing polishing work of the workpiece 3, a machining surface of about 0.2μm (Rmax) degree surface roughness is obtained in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an abrasive article made of a hard and brittle material, a metal material and the like and a vibration magnetic polishing apparatus.

[0002]

2. Description of the Related Art In the processing of metallic materials, a shape is created by cutting, and when higher shape accuracy is required, grinding or polishing is performed. When a particularly smooth surface or mirror surface is required, polishing is performed. Further, also in the processing of hard and brittle materials, a grinding process is performed after sintering to improve the surface roughness and dimensional accuracy, and then a method of further polishing to improve the surface roughness is generally performed. ing. Further, in the processing of glass, which is a kind of hard and brittle material, grinding is performed to create a shape, and particularly in processing of a lens that is an optical component, grinding (CG) is performed to create a shape. After that, polishing is usually performed to obtain a required shape accuracy and a glossy surface.

As described above, in the removal processing of metal materials and hard and brittle materials, for parts requiring high processing accuracy and surface roughness, it is preferable to perform shape processing by grinding and then finish processing by polishing. It is common. The polishing process includes a lapping process using free abrasive grains as well as a superfinishing process using fixed abrasive grains and a honing process. These processing methods are conventionally used generally.

Further, with the recent progress in processing technology,
Several attempts at new polishing methods have been proposed and put to practical use. One of them is a polishing method using magnetism. In this polishing method, a polishing agent (magnetic polishing agent) containing a magnetic material attracted to a magnet is held in contact with the surface of a workpiece by a magnetic force applied from the outside, so that the workpiece and the magnetic polishing agent are This is a method in which machining is performed by giving relative motion between them. Since the abrasive grains can be held by magnetic force,
It is known that the effect is particularly exerted on the inner peripheral processing of a pipe and the polishing processing of a workpiece having a complicated shape, which are difficult to perform by the conventional polishing processing.

[0005]

In the ordinary polishing process, the pressure between the work piece and the abrasive grains and the relative speed of the work piece and the abrasive grains are major factors that determine the processing amount. The relationship can be expressed as in equation (1). Therefore, if the relative moving speed is the same, the amount of processing is increased and the processing efficiency is improved by increasing the pressure between the work piece and the abrasive grains, and the pressure between the work piece and the abrasive grains is increased. If the value becomes lower, the processing amount decreases and the processing efficiency decreases. (Preston's law)

[0006]

[Equation 1]

In the magnetic polishing method described in the preceding paragraph, particles of the abrasive can be brought into relatively free contact with the work by placing the work in a magnetic field. Like polishing with grains or loose abrasive grains,
Since there is no physical means for fixing the abrasive grains and forcing them to the work piece, there is a problem that the working efficiency is low.

An object of the present invention is to solve this problem.

[0009]

[Means for Solving the Problems] In order to solve the above problems, as a result of earnest research, "a method for producing an abrasive article characterized by polishing an object to be processed while applying an alternating magnetic field to a magnetic abrasive" Or "a magnetic abrasive, a magnetic circuit forming means for holding the magnetic abrasive on the surface of the workpiece to be processed, and a magnetic field applying means for applying an alternating magnetic field to the magnetic abrasive. 3. An oscillating magnetic polishing apparatus according to claim 2, or "the magnetic circuit forming means is a direct current driven electromagnet, and the magnetic field applying means is the electromagnet driven by superimposing alternating current. 3. The vibration magnetic polishing apparatus "or" the vibration magnetic polishing apparatus according to claim 2, wherein the magnetic field applying means comprises an electromagnet for applying an alternating magnetic field in a direction perpendicular to the magnetic circuit. It found that can solve and accomplished the present invention.

[0010]

The pressure between the magnetic abrasive and the work piece is proportional to the magnetic force passing through the magnetic circuit because the abrasive particles press the work piece. Therefore, by changing this magnetic force, the force of the abrasive particles pressing the work piece changes. Therefore, according to the method described in the preceding paragraph, an electric wire is wound around a member forming a magnetic circuit to form a coil, and a current in which an alternating current is superimposed on a bias current as shown in FIG. 5 is supplied thereto. As a result, as shown in FIG.
4 regularly generates a force in the direction of striking the surface of the workpiece. This is because, as shown in the ultrasonic machining method using loose abrasive grains, by applying a force in the direction of striking the surface of the workpiece through the abrasive grains, the removal rate of the workpiece becomes high and the machining efficiency increases. Is dramatically improved.

The relative velocity between the magnetic abrasive and the work piece that affects the removal rate of the work piece is determined by the relative motion of the abrasive particles and the work piece. Therefore, a magnetic circuit that generates a magnetic field that holds the magnetic abrasive and another magnetic circuit that is substantially orthogonal to the magnetic field are provided, and an alternating magnetic field is applied to change the magnetic poles to form abrasive particles made of permanent magnets. Movement in the direction of rotation can be achieved (Fig. 8). As a result, the relative speed between the magnetic abrasive and the work piece is improved, the removal rate of the work piece is increased according to Preston's law, and the processing efficiency is dramatically improved.

The alternating current applied to the electromagnet needs to be changed according to the particle size of the magnetic polishing agent, but the driving frequency is preferably several Hz to 100 kHz. 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.

[0013]

FIG. 1 is a schematic diagram of a first embodiment in which the vibration magnetic polishing apparatus according to the present invention is applied to the circumferential machining of a cylindrical member. The coil 2 is wound around the magnetic circuit 1, and the coil 2
A bias current and a current in which an alternating current is superimposed flow on the. A gap is provided in a part of the magnetic circuit 1, and the workpiece 3 is inserted therein and rotated about the axis of the cylinder. A magnetic polishing material 4 is held between the work piece 3 and the magnetic pole on the end surface of the magnetic circuit 1. In this embodiment, the magnetic abrasive material 4 is made by crushing ferrite into powder.
The magnetic circuit 1 uses a ferrite transformer core. Further, the frequency of the alternating current to be superimposed on the bias current is 10 to several tens of kHz, and is supplied to the coil 2 from the oscillator 5 provided outside. In this embodiment, the magnetic circuit 1 is applied with a direct current superimposed with an alternating current of 10 Hz, and a stainless steel material is polished to obtain a machined surface having a surface roughness of about 0.2 μm (Rmax) in a short time. I was able to.

FIG. 2 is a schematic diagram of a second embodiment in which the vibration magnetic polishing apparatus according to the present invention is applied to the processing of the glass lens 6. A coil 2 is wound around the magnetic circuit 1, and a current in which a bias current and an alternating current are superimposed flows through the coil 2. A gap is provided in a part of the magnetic circuit, and the glass lens 6 which is the work held by the employee 7 is inserted therein. The employee 7 is rotationally driven by a rotating means provided outside. A magnetic polishing material 4 is inserted into the end surface of the magnetic circuit 1 with respect to the processed portion of the glass lens 6. The shape of the end surface of the magnetic circuit needs to be changed according to the shape of the glass lens 6 to be processed.

FIG. 3 is a schematic view of a third embodiment in which the present invention is applied to a circular glass plate material. The plate glass 9, which is a workpiece, has its circumference held by three rollers 8 and is further driven to rotate. FIG. 4 is a side view of this embodiment. A part of the plate glass 9 is inserted into the gap of the magnetic circuit 1 via the magnetic polishing material 4 in the state shown in FIG. In the coil 2 wound around the magnetic circuit 1, a current in which a bias current and an alternating current similar to those in the above-described embodiment are superposed is flowed to perform processing. Further, the magnetic circuit 1 is periodically moved in the moving direction 10 as shown in FIG.
It may be processed.

FIG. 5 is a graph showing a coil drive current waveform. The coil drive current waveform 18 shown here is
The bias current 13 is not limited to the superimposed sine wave-shaped alternating current, and may be the superimposed rectangular wave. FIG. 7 is a fourth embodiment in which the vibrating magnetic polishing apparatus according to the present invention is applied to the processing of the end surface of a cylindrical member. Further, FIG. 8 is a schematic view showing the processing principle. A coil 2 is wound around a magnetic circuit 1 for holding a magnetic abrasive 4 made of a permanent magnet, and a direct current is passed through the coil 2 to hold the magnetic abrasive 4. A gap is provided in a part of the magnetic circuit 1, and the workpiece 3 is inserted therein and rotated about the axis of the cylinder. The magnetic polishing material 4 is held between the workpiece 3 and the magnetic pole on the end surface of the magnetic circuit 1. In this example, the magnetic abrasive used was a powder of a permanent magnet made of ferrite crushed and crushed. Further, another magnetic circuit 21 for generating a magnetic field in a direction substantially perpendicular to the magnetic field generated in the magnetic circuit 1 is provided and installed. By applying an alternating current to the magnetic circuit 21, an alternating magnetic field is generated.
The frequency of the alternating current is 10 to several tens of kHz, and the coil 12 wound around the magnetic circuit 21 from the oscillator 5 provided outside.
Is supplied to. Due to this alternating magnetic field, the magnetic abrasive 4 made of a permanent magnet held on the surface of the workpiece receives a couple 10 as shown in FIG. 8 and starts to move in the rotational direction. As a result, the end surface of the workpiece is efficiently polished.

FIG. 9 is a fifth embodiment in which the vibration magnetic polishing apparatus according to the present invention is applied to the processing of glass material. A coil 2 is wound around the magnetic circuit 1 to hold the magnetic polishing material 4, and a direct current flows there. A glass material 9 as a workpiece is inserted so as to cover a magnetic field line generated by providing a gap in a part of the magnetic circuit 1. The glass material 9 is rotationally driven by a rotating means provided outside. The magnetic polishing material 4 is provided on the end surface of the magnetic circuit 1 which corresponds to the processed portion of the glass material 9.
Has been inserted. Further, another magnetic circuit 21 for generating a magnetic field in a direction substantially perpendicular to the magnetic field generated in the magnetic circuit 1 is provided and installed. An alternating magnetic field is generated by applying an alternating current to the coil wound around this magnetic circuit. The frequency of the alternating current is 10 to several tens of kHz, and is supplied to the coil 12 wound around the magnetic circuit 21 from the oscillator 5 provided outside. In this embodiment, the coil 12
By applying an alternating current of 10 Hz and polishing the glass material using a magnetic abrasive 4 obtained by crushing ferrite, a machined surface having a surface roughness of about 0.1 μm (Ra) could be obtained in a short time. .

The coil drive current waveform may be a rectangular wave instead of a sine wave AC current.

[0019]

As described above, by performing the vibration magnetic polishing process by the method shown in the embodiment of the present invention, extremely high efficiency process can be realized.
In particular, a great effect was obtained for hard and brittle materials.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment in which the present invention is applied to machining a cylindrical member.

FIG. 2 is a schematic view of an example in which the present invention is applied to a glass lens.

FIG. 3 is a schematic view of an example in which the present invention is applied to the processing of sheet glass.

FIG. 4 is a side view of the embodiment shown in FIG.

FIG. 5 is a schematic diagram showing a drive current of the present invention.

FIG. 6 is a principle diagram showing the behavior of the abrasive grains of the present invention.

FIG. 7 is a schematic diagram in which the present invention is applied to end face processing of a cylindrical member.

FIG. 8 is a schematic diagram showing the processing principle of the present invention. .

FIG. 9 is a schematic view of an example in which the present invention is applied to glass processing.

[Explanation of symbols]

 1 ... Magnetic circuit 2 ... Coil 3 ... Workpiece 4 ... Magnetic polishing material 5 ... Oscillator 6 ... Glass lens (workpiece) 9 ... Flat glass (workpiece) ) 12 ... alternating magnetic field generating coil 13 ... bias current 14 ... magnetic abrasive (abrasive grain) 18 ... coil drive current waveform 19 ... bearing 21 ... orthogonal magnetic circuit

Claims (4)

[Claims] 1. A method of manufacturing an abrasive article, which comprises polishing an object to be processed while applying an alternating magnetic field to a magnetic abrasive. 2. A magnetic abrasive, a magnetic circuit forming means for holding the magnetic abrasive on a surface of a workpiece to be processed, and a magnetic field applying means for applying an alternating magnetic field to the magnetic abrasive. Characteristic vibration magnetic polishing device. 3. The vibrating magnetic polishing apparatus according to claim 2, wherein the magnetic circuit forming means is an electromagnet driven by direct current, and the magnetic field applying means is the electromagnet driven by superposing alternating current. . 4. The oscillating magnetic polishing apparatus according to claim 2, wherein the magnetic field applying means comprises an electromagnet that applies an alternating magnetic field in a direction perpendicular to the magnetic circuit.