Process for preparing magnet made of resin

• US 5,145,614 A
• Filed: 02/14/1991
• Issued: 09/08/1992
• Est. Priority Date: 02/14/1990
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kuroda, Masaaki
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): EASTLEY, BRIAN
• Application Number:
  US07/655,142
• Time in Patent Office: 572 Days
• Field of Search: 264/24, 264/DIG. 58, 148/101, 148/302
• US Class Current: 264/429
• CPC Class Codes: B29C 45/0013 using fillers dispersed in the moulding material, e.g. metal particles
• CPC Class Codes: B29C 70/62 the filler being oriented during moulding for short fibres B29C70/14
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2995/0008 Magnetic or paramagnetic
• CPC Class Codes: H01F 41/028 Radial anisotropy for rotor or stator bodies H02K15/02
• CPC Class Codes: Y10S 264/58 Processes of forming magnets

Abstract

The process for preparing a multi-polar anisotropic resinous magnet by preparing a multi-polar anisotropic resinous magnet by injecting a liquid reaction curable resin containing a magnetic powder into a mold for molding and applying a magnetic field for multiple-pole orientation thereon; the reaction curable resin is injected into a mold for molding set between a large number of magnetic poles arranged at predetermined intervals including magnetic poles with freely convertible magnetism and back yokes opposed to these magnetic poles; a magnetic flux flows in one direction to the back yokes with the respective magnetic poles being made the same polarity, maintaining the resin under uncured state, to localize and orient the magnetic powder in the resin corresponding to the magnetic flux. The reaction curing of the resin is completed while applying a magnetic field obtained by converting the magnetism of the magnetic poles to the desired multi-polar anisotropy of the resinous magnet, thereby localizing and orienting the magnetic powder within the resin corresponding to the magnetic field.

Claims

1. A process for preparing a multi-polar anisotropic resinous magnet by injecting a liquid reaction curable resin containing magnetic powder into a mold for molding and applying a magnetic field for multiple-pole orientation thereon, comprising:

(a) injecting said reaction curable resin into a mold for molding provided between a large number of magnetic poles arranged at predetermined intervals including magnetic poles with freely convertible magnetism and back yokes opposed to these magnetic poles;

(b) permitting a magnetic flux to flow in one direction to the back yokes with the respective magnetic poles being made the same polarity, while maintaining the resin under uncured state injected in said magnetic flux, to localize and orient the magnetic powder in said resin corresponding to said magnetic flux; and

(c) after completion of the step (b), completing the reaction curing of the resin while applying a magnetic field obtained by converting the magnetism of said magnetic poles to the desired multi-polar anisotropy of the resinous magnet, thereby to magnetize the magnetic powder within the resin corresponding to said magnetic field.

5. Use of the molded magnet prepared according to the preparation process of claim 1 for an image forming device.

2. A process for preparing a magnet made of a resin comprising:

mixing a first material comprising magnetic material and a second material comprising a reaction curable agent;

preparing a mold for molding of a hollow cylindrical magnet, said mold having a cavity into which said materials are injected, said mold comprising a part of the cavity and comprising;

a magnetic circuit forming member for forming a first magnetic circuit which passes through the cavity;

a first coil for energizing said magnetic circuit forming member and

a second coil positioned in a position around said cavity and forming a second magnetic circuit for forming a magnetic pole of the molded magnet;

injecting said mixed materials into said cavity;

causing the magnetic material in the material injected into said cavity to form a partial aggregating state in said cavity by a magnetic force generated by said first magnetic circuit;

thereafter magnetizing and orienting by said second magnetic circuit the magnetic material in the partial aggregating state formed by said first magnetic circuit to form the magnetic pole of the magnet molded, wherein a portion in the aggregating state formed by said step is magnetized; and

removing the molded magnet from the cavity.

3. A preparation process according to claim 2, wherein the material injected into said cavity contains a nylon type main agent, an epoxy type reaction curing agent and a magnetic material, and the ratio of said magnetic material to the whole material injected is from 50-70% by weight.

4. A preparation process according to claim 3, wherein said hollow cylindrical cavity forms a magnet for motor.

6. A process for preparing a multi-polar anisotropic resinous magnet by injecting a liquid reaction curable resin containing magnetic powder into a mold for molding and applying a magnetic field from magnetic poles for multi-polar orientation comprising:

(a) injecting said reaction curable resin into a mold for molding provided between a large number of magnetic poles with freely convertible magnetism and back yokes opposed to these magnetic poles;

(b) applying a magnetic field from the magnetic poles with a pole number smaller than a desired pole number on uncured resin injected into the mold for molding, thereby localizing and orienting the magnetic powder in said resin to a magnetic force effective region corresponding to said magnetic field; and

(c) further completing reaction curing of the resin under a state where the magnetic field is applied from the desired pole number on the localized and oriented magnetic powder in the step (b) thereby obtaining a magnet comprising a multi-polar polar anisotropic cured resin with the magnetic powder localized and oriented in the magnetic force effective region corresponding to said magnetic field.

7. A process for preparing a magnet made of a resin comprising:

mixing a main agent material, a reaction curing agent and a magnetic material;

preparing a mold for molding of said magnet, wherein said mold has the following members, namely;

a first cylindrical member having a cavity for molding of the cylindrical magnet;

a second cylindrical member arranged concentrically with said first cylindrical member;

a plurality of magnet members for formation of a first magnetic circuit arranged radially between said first and second cylindrical members;

a yoke member for formation of the magnetic pathway arranged and between said first and second cylindrical members; and

a coil member wound around said yoke member for formation of a second magnetic circuit;

localizing the magnetic material by a magnetic force of the first magnetic circuit so that said magnetic material is aggregatively distributed at a peripheral portion of the cavity of the cylindrical member rather than a central portion;

thereafter magnetizing said aggregatively distributed portion by the second magnetic circuit; and

curing the injected marital within said cavity while maintaining the localized and magnetized state of the magnetic material.

8. A process according to claim 7, wherein said mold has further the following members:

a number n of said magnet members constituting said first magnetic circuit has the relationship relative to the number N of magnetic poles of the magnetic member of N=X·

n (where X is an integer).

9. Use of the molded pole prepared according to the preparation process of claim 7 for an image forming device.