Method for producing permanent magnet and sintered compact and production apparatus for making green compacts

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• preliminarily compacting a magnet powder to a density which is at least 1.2 times a natural filling density of the magnet powder;
• inserting the preliminary compact of the magnet powder in the rubber mold outside the die-press machine;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the magnet powder therein by a punch in the die-press machine under a magnetic field to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the magnet powder to fall under gravity from a powder pan into the rubber mold until the top of the magnet powder arrives at an upper frame which prevents the magnet powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density which is at least 1.2 times a natural filling density of the magnet powder, by means of vibration, pressing the magnet powder with pushing or both;
• covering an upper open part of the rubber mold with a cover;
• applying an instantaneous magnetic field or stronger magnetic field more than 8 kOe to the magnet powder in the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the magnet powder therein by a punch in the die-press machine without a magnetic field;
• wherein the natural filling density is obtained by allowing the magnet powder to fall under gravity from a powder pan into the rubber mold until the top of the magnet powder arrives at an upper frame which prevents the magnet powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press preliminarily compacting a magnet powder to a density which is at least 1.2 times a natural filling density of the magnet powder;
• inserting the prliminary compact of the magnet powder in the rubber mold outside the die-press machine;
• covering an upper open part of the rubber mold with a cover;
• applying an instantaneous magnetic field or stronger magnetic field than 8kOe to the magnet powder in the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the magnet powder therein by a punch in the die-press machine without a magnetic field or under a magnetic field to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the magnet powder to fall under gravity from a powder pan into the rubber mold until the top of the magnet powder arrives at an upper frame which prevents the magnet powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold.

A production method of a green magnet compact, characterized by repeatedly carrying out:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density at least 1.2 times a natural filling density of the magnet powder, by means of vibration, pressing the magnet powder with a pushing or both;
• covering an upper open portion of the rubber mold with a cover;
• applying instantaneous magnetic field or stronger static magnetic field than 8kOe to the magnet powder in the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the magnet powder therein by a punch in the die-press machine under a magnetic field or without a magnetic field to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the magnet powder to fall under gravity from a powder pan into the rubber mold until the top of the magnet powder arrives at an upper frame which prevents the magnet powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold.

A production method of a green magnet compact, comprising repeatedly carrying out:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• preliminarily compacting a magnet powder to a density at least 1.2 times a natural filling density of the magnet powder, by means of vibration, pressing the magnet powder with a pushing or both;
• inserting the preliminary compact of the magnet powder in the rubber mold outside the die-press machine;
• covering an upper open portion of the rubber mold with a cover;
• applying instantaneous magnetic field or stronger magnetic field than 8kO3 to the magnet powder in the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the magnet powder therein by a punch in the die-press machine under a magnetic field or without a magnetic field to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the magnet powder to fall under gravity from a powder pan into the rubber mold until the top of the magnet powder arrives at an upper frame which prevents the magnet powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold.

A production method of a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least side portion thereof and is open at a top thereof;
• filling a cavity of the rubber mold with a slurry containing maget powder and a solvent in the rubber mold in or outside a die-press machine is provided with an upper punch, a filter and a water suction channel formed in the upper punch;
• placing the filled rubber mold in the die-press machine;
• placing the filter between the upper punch and the open top of the rubber mold;
• compacting the filled rubber mold and the magnet powder therein, thereby sucking the solvent through the filter and the water-suction channel.

A production method of a sintered compact having a density of 90% or more, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a fine powder of material except for Magnet material having average particle diameter of 50 .mu.m or less and being essentially free of organic binder to a density which is at least 1.15 times a natural filling density of the fine powder, by means of vibration, pressing the fine powder with a pushing or both;
• placing the filled rubber mold in the die-press machine;
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the fine powder;
• and
• sintering the green compact;
• wherein the natural filling density is obtained by allowing the fine powder from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold.

A production method of a sintered compact having a density of 90% or more, comprising:

• preparing a rubber mold which comprises rubber at least in a side portion thereof;
• weighing fine powder of material except for magnet material, having average particle size of 50 m or less and being essentially free of organic binder, to provide a predetermined amount;
• filling a cavity of the rubber mold with the fine powder to a density at least 1.15 times a natural filling density, outside a die-press machine;
• placing the filled rubber mold in the die-press machine;
• compacting the rubber mold and the fine powder by a punch of the die-press machine thereby obtaining a green compact;
• withdrawing the green compact from the rubber mold;
• and
• sintering the green compact;
• wherein the rubber mold is mounted on a conveying means for circulating the same around and intermittently moving the same between positions where said filling, compacting and withdrawing are carried out, and, further wherein the natural filling density is obtained by allowing the fine powder to fall under gravity into the rubber mold from a powder pan until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing from the rubber mold, the distance between the bottom end of the powder pan and the bottom of the rubber mold is 3.7 times the depth of cavity of the rubber mold.

A production method of a sintered compact having a density of 90% or more, comprising:

• preparing a rubber mold which comprises rubber at least in a side portion thereof;
• weighing fine powder of material except for magnet material, having average particle size of 50 .mu.m or less and being essentially free of organic binder, to provide a predetermined amount;
• filling a cavity of the rubber mold with the fine powder to a density at least 1.15 times a natural filling density, outside a die-press machine;
• placing the filled rubber mold in the die-press machine;
• compacting the rubber mold and the fine powder by a punch of the die-press machine thereby obtaining a green compact;
• withdrawing the green compact from the rubber mold;
• and
• sintering the green compact;
• wherein the rubber mold is mounted on a conveying means for linearly and intermittently
• conveying the rubber molds between positions where said filling, compacting and withdrawing are carried out, and, further wherein the natural filling density is obtained by allowing the fine powder to fall under gravity into the rubber mold from a powder pan until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing from the rubber mold, the distance between the bottom end of the powder pan and the bottom of the rubber mold is 3.7 times the depth of cavity of the rubber mold.

A production method for producing a sintered compact having a density of 90% or more, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a fine powder of a material other than a magnet material having an average particle diameter of 50 .mu.m or less to a density which is at least 1.15 times a natural filling density of the fine powder, by means of vibration, pressing the fine powder with pushing or both;
• placing the filled rubber mold in the die-press machine;
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the fine powder;
• and
• sintering the green compact;
• wherein the natural filling density is obtained by allowing the fine powder to fall from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold.

A production method for producing a sintered compact having a density of 90% or more, comprising:

• preparing a rubber mold which comprises rubber at least in a side portion thereof;
• weighing fine powder of a material other than a magnet material, having an average particle size of 50 .mu.m or less to provide a predetermined amount;
• filling a cavity of the rubber mold with the fine powder to a density at least 1.15 times a natural filling density, outside a die-press machine;
• placing the filled rubber mold in the die-press machine;
• compacting the rubber mold and the fine powder by a punch of the die-press machine thereby obtaining a green compact;
• withdrawing the green compact from the rubber mold;
• and
• sintering the green compact;
• wherein the rubber mold is mounted on a conveying means for circulating the same around and intermittently moving the same between positions wherein said filling, compacting and withdrawing are carried out, and, further wherein the natural filling density is obtained by allowing the fine powder to fall under gravity into the rubber mold from a powder pan until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing from the rubber mold, the distance between the bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of cavity of the rubber mold.

A production method for producing a sintered compact having a density of 90% or more, comprising:

• preparing a rubber mold which comprises rubber at least in a side portion thereof;
• weighing fine powder of a material other than a magnet material, having an average particle size of 50 .mu.m or less to provide a predetermined amount;
• filling a cavity of the rubber mold with the fine powder to a density at least 1.15 times a natural filling density, outside a die-press machine.
• placing the filled rubber mold in the die-press machine;
• compacting the rubber mold and the fine powder by a punch of the die-press machine thereby obtaining a green compact;
• withdrawing the green compact from the rubber mold;
• and
• sintering the green compact,
• wherein the rubber mold is mounted on a conveying means for linearly and intermittently conveying the rubber molds between positions where said filling, compacting and withdrawing are carried out, and, further wherein the natural filling density is obtained by allowing the fine powder to fall under gravity into the rubber mold from a powder pan until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing from the rubber mold, the distance between the bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of cavity of the rubber mold.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density which is at least 1.2 times a natural filling density of the fine powder, by means of stirring the magnet powder by a reciprocating blade mounted in a feeder box to fill the magnet powder into the rubber mold, said feeder box being located on the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the fine powder to fall from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold;
• and
• wherein a magnetic field is applied to the filled rubber mold containing the magnet powder before or during the compacting of the filled rubber mold and the fine powder therein by the punch in the die-press machine.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density which is at least 1.2 times a natural filling density of the fine powder, by means of vibrating the magnet powder by a vibrator mounted in a feeder box to fill the magnet powder into the rubber mold, said feeder box being located on the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the fine powder to fall from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold;
• and
• wherein a magnetic field is applied to the filled rubber mold containing the magnet powder before or during the compacting of the filled rubber mold and the fine powder therein by the punch in the die-press machine.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density which is at least 1.2 times a natural filling density of the fine powder, by means if imparting vibration to the magnet powder while the magnet powder is conveyed on a conveyor by a vibrator slidably attached to a lower side of the conveyor and then dropping the magnet powder into the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the fine powder to fall from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold;
• and
• wherein a magnetic field is applied to the filled rubber mold containing the magnet powder before or during the compacting of the filled rubber mold and the fine powder therein by the punch in the die-press machine.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density which is at least 1.2 times a natural filling density of the fine powder, by means of stirring the magnet powder with blades which are spirally secured around a screw rod coaxially mounted in a container and then dropping the magnet powder into the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the fine powder to fall from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold;
• and
• wherein a magnetic field is applied to the filled rubber mold containing the magnet powder before or during the compacting of the filled rubber mold and the fine powder therein by the punch in the die-press machine.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density which is at least 1.2 times a natural filling density of the fine powder, by densifying the magnet powder by rolls located on the sides of a conveyor on which the magnet powder is conveyed and dropping the densified magnet powder into the rubber mold;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the fine powder to fall from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold;
• and
• wherein a magnetic field is applied to the filled rubber mold containing the magnet powder before or during the compacting of the filled rubber mold and the fine powder therein by the punch in the die-press machine.

A production method for producing a green magnet compact, comprising:

• preparing a rubber mold which comprises rubber in at least a side portion thereof and which is located outside a die-press machine;
• filling a cavity in the rubber mold with a magnet powder to a density which is at least 1.2 times a natural filling density of the fine powder under gravity and a magnetic field;
• placing the filled rubber mold in the die-press machine;
• and
• compacting the filled rubber mold and the fine powder therein by a punch in the die-press machine to obtain a green compact of the magnet powder;
• wherein the natural filling density is obtained by allowing the fine powder to fall from a powder pan into the rubber mold until the top of the fine powder arrives at an upper frame which prevents the fine powder from overflowing the rubber mold, the distance between a bottom end of the powder pan and the bottom of the rubber mold being 3.7 times the depth of the cavity of the rubber mold;
• and
• wherein a magnetic field is applied to the filled rubber mold containing the magnet powder before or during the compacting of the filled rubber mold and the time powder therein by the punch in the die-press machine.