Abstract: A method for manufacturing a powder magnetic core, the method including: forming a soft magnetic powder (SMP) layer by putting an SMP having a surface on which an insulating coating film is formed into a space surrounded by a lower punch and a die; forming a pressed powder by compressing the SMP layer in the die by the lower punch and an upper punch; and causing the pressed powder and the die to slide relative to each other and then removing the pressed powder from the die is provided. In forming the SMP layer, a different powder different from the SMP is put into the space before and after the SMP is put into the space and a different powder layer having a spring back rate higher than that of the SMP layer by 0.6-1.1% is formed on upper and lower sides of the SMP layer.

Abstract: A method for manufacturing a powder magnetic core, the method including: forming a soft magnetic powder (SMP) layer by putting an SMP having a surface on which an insulating coating film is formed into a space surrounded by a lower punch and a die; forming a pressed powder by compressing the SMP layer in the die by the lower punch and an upper punch; and causing the pressed powder and the die to slide relative to each other and then removing the pressed powder from the die is provided. In forming the SMP layer, a different powder different from the SMP is put into the space before and after the SMP is put into the space and a different powder layer having a spring back rate higher than that of the SMP layer by 0.6-1.1% is formed on upper and lower sides of the SMP layer.

Abstract: In molding a compact having portions of an equal thickness on opposite sides of a through-hole, an advancing speed of a holder holding a powder material is adjusted before the holder is advanced and retracted over a die cavity of a die. Specifically, a first preparation of determining in advance a relation between the advancing speed of the holder and a packing density of the powder material packed in the die cavity at each of the portions to be of an equal thickness of the compact on opposite sides of the through-hole is made; and, based on the relation determined in the first preparation, the advancing speed of the holder is adjusted to a speed at which the packing density becomes uniform. Thus, the packing density of the powder material packed in the die cavity can be uniformized, so that the dimensional accuracy of the molded compact can be improved.

Abstract: A powder for molding is a mixture of first constituent particles, which are made up of first metal base particles, and second constituent particles, which are made up of second metal base particles. A first lubricant concentration that is a mass proportion of a first internal lubricant adhered to the surface of the first metal base particles with respect to the total of the first constituent particles, is greater than a second lubricant concentration that is a mass proportion of a second internal lubricant that is adhered to the surface of the second metal base particles with respect to the total of the second constituent particles.

Abstract: There is provided a method for controlling a powder compacting apparatus including: a die having a hollow; an upper punch and a floating lower punch; a first actuator that pushes down the upper punch; a second actuator that controls a floating load of the floating lower punch; and a stopper that defines a pressurization stop position of the floating lower punch. The powder compacting apparatus is configured such that the first actuator is operated to push down the upper punch to pressurize powder charged into the cavity, and the second actuator is controlled to pressurize the powder such that a load acting on the powder during pressurization becomes a prescribed floating load required to compact the powder. The method includes reducing the floating load in a stepwise manner after completion of the pressurization.

Abstract: In molding a compact having portions of an equal thickness on opposite sides of a through-hole, an advancing speed of a holder holding a powder material is adjusted before the holder is advanced and retracted over a die cavity of a die. Specifically, a first preparation of determining in advance a relation between the advancing speed of the holder and a packing density of the powder material packed in the die cavity at each of the portions to be of an equal thickness of the compact on opposite sides of the through-hole is made; and, based on the relation determined in the first preparation, the advancing speed of the holder is adjusted to a speed at which the packing density becomes uniform. Thus, the packing density of the powder material packed in the die cavity can be uniformized, so that the dimensional accuracy of the molded compact can be improved.

Abstract: There is provided a method for controlling a powder compacting apparatus including: a die having a hollow; an upper punch and a floating lower punch; a first actuator that pushes down the upper punch; a second actuator that controls a floating load of the floating lower punch; and a stopper that defines a pressurization stop position of the floating lower punch. The powder compacting apparatus is configured such that the first actuator is operated to push down the upper punch to pressurize powder charged into the cavity, and the second actuator is controlled to pressurize the powder such that a load acting on the powder during pressurization becomes a prescribed floating load required to compact the powder. The method includes reducing the floating load in a stepwise manner after completion of the pressurization.

Abstract: There is provided a method for controlling a powder compacting apparatus including: a die having a hollow; an upper punch; a floating lower punch; a first actuator that pushes down the upper punch; a second actuator that controls a floating load of the floating lower punch; and a stopper that defines a pressurization stop position of the floating lower punch. The powder compacting apparatus is configured such that the first actuator is operated to push down the upper punch to pressurize powder charged into the cavity, and the second actuator is controlled to pressurize the powder such that a load acting on the powder during pressurization becomes a prescribed floating load required to compact the powder. The method includes causing the first actuator to reduce a descending speed of the upper punch when the floating lower punch reaches a position at a prescribed distance from the stopper.

Abstract: A powder for molding is a mixture of first constituent particles, which are made up of first metal base particles, and second constituent particles, which are made up of second metal base particles. A first lubricant concentration that is a mass proportion of a first internal lubricant adhered to the surface of the first metal base particles with respect to the total of the first constituent particles, is greater than a second lubricant concentration that is a mass proportion of a second internal lubricant that is adhered to the surface of the second metal base particles with respect to the total of the second constituent particles.