Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Consolidation of powder prior to sintering
Reexamination Certificate
2001-07-11
2003-11-18
Jenkins, Daniel J. (Department: 1742)
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Consolidation of powder prior to sintering
C425S078000
Reexamination Certificate
active
06649124
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a powder pressing apparatus and a powder pressing method. More specifically, the present invention relates to a powder pressing apparatus and a powder pressing method for manufacture of a compact to be made into a R—Fe—B magnet.
2. Description of the Related Art
FIG. 12
shows a primary portion of a powder pressing apparatus
1
for pressing a powder into a compact. According to the powder pressing apparatus
1
, hollow cylindrical compacts each having, for example, a height of 6.4 mm, an inner diameter of 1.8 mm and an outer diameter of 4 mm are formed.
Now, an operation of the powder pressing apparatus
1
will be described briefly.
First, a die
2
is raised to a predetermined position, whereupon a feeder box
3
is moved above the die
2
, allowing the powder contained in the feeder box
3
to fall into cavities
4
of the die
2
. The feeder box
3
is then withdrawn, with its lower edge wiping the powder. Thereafter, an upper punch (no illustrated) is lowered to press the powder into compacts in the cavities
4
. Then, the upper punch is raised whereas the die
2
is lowered, so that the compacts are out of the die. The compacts are then pushed by a front face
3
a
of the feeder box
3
, and slid on the die
2
and a base plate
5
off pressing area.
Since the compacts are soft, pushing by the feeder box
3
is a desirable method of taking out small compacts after the compacting. However, if a number of compacts are pushed as shown in
FIG. 12
, in a direction of the row of compacts, then the compacts can hit thereby chipping or breaking each other, and the probability increases with the number of compacts in the row. This has limited the number of compacts which can be formed per press, and has been a cause of low productivity.
Alternatively, the compact can be taken out by a robot which is movable in the sliding direction of the feeder box
3
. However, it is very difficult for the robot to grasp the small and fragile compact, in a short handling time such as a second or two.
The problem is even more serious in a compact used in manufacture of a Nd—Fe—B magnet, in which the compact is very soft and even more difficult to handle, because the compact is made into a low density for the sake of magnetic property, and a lubricant is added for improved orientation.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a powder pressing apparatus and a powder pressing method capable of improving yield and productivity.
According to an aspect of the present invention, there is provided a powder pressing apparatus which presses a powder into compacts in a plurality of cavities formed in a die, comprising: powder supply means which supplies the powder into the cavities; orienting means which orients the powder in the cavities; pressing means which presses the powder in the cavities into the compacts; and pushing means which pushes the compacts off the die; wherein none of the cavities overlap with another in a direction of pushing the compacts.
According to another aspect of the present invention, there is provided a powder pressing method for pressing a powder into compacts in a plurality of cavities formed in a die, comprising: a step of supplying the powder into the cavities; a step of orienting the powder in the cavities; a step of pressing the powder in the cavities into the compacts; and a step of pushing the compacts off the die, without allowing any of the compacts to contact another.
In this invention, none of the cavities overlap with another, in the pushing direction of the compacts. Therefore, each of the compacts can be taken out without making contact with another. Thus, yield is improved and productivity can be increased. Even if the compacts are oriented, taking can be performed favorably.
According to still another aspect of the present invention, there is provided a powder pressing apparatus which presses a powder into a compact in a cavity formed in a die, comprising: powder supply means which supplies the powder into the cavity; orienting means which orients the powder in the cavity; pressing means which presses the powder in the cavity into the compact; and pushing means which pushes the compact off the die; wherein the pushing means is provided by a flexible and elastic member.
According to still another aspect of the present invention, there is provided a powder pressing method for pressing a powder into a compact in a cavity formed in a die, comprising: a step of supplying the powder into the cavity; a step of orienting the powder in the cavity; a step of pressing the powder in the cavity into the compact; and a step of pushing the compact off the die, by using a flexible member.
In this invention, since the compact is pushed by the flexible member, pushing force can be applied gradually, instead of all at once, to the compact at the time of pushing. Therefore, even the soft compact can be pushed successfully, without being broken or tipped over.
According to still another aspect of the present invention, there is provided a powder pressing apparatus which presses a powder into a compact in a cavity formed in a die, comprising: powder supply means which supplies the powder into the cavity; orienting means which orients the powder in the cavity; pressing means which presses the powder in the cavity into the compact; pushing means which pushes the compact off the die; and an anti-wear layer provided in a region where the compact pushed by the pushing means slides.
According to still another aspect of the present invention, there is provided a powder pressing method for pressing a powder into a compact in a cavity formed in a die, comprising: a step of supplying the powder into the cavity; a step of orienting the powder in the cavity; a step of pressing the powder in the cavity into the compact; and a step of pushing thereby sliding the compact off the die, on an anti-ware layer.
In this invention, when being pushed, the compact is slid on the anti-wear layer that has a small surface roughness. Therefore, friction force associating with the sliding compact can be reduced, and the compact can be pushed without being broken.
According to still another aspect of the present invention, there is provided a powder pressing apparatus which presses a powder into a compact in a cavity formed in a die, comprising: powder supply means which supplies the powder into the cavity; orienting means which orients the powder in the cavity; pressing means which presses the powder in the cavity into the compact; and pushing means which pushes the compact off the die; and applying means which applies a die lubricant to the die (through-hole) but not to a region where the compact slides.
According to still another aspect of the present invention, there is provided a powder pressing method for pressing a powder into a compact in a cavity formed in a die, comprising: a step of applying a die lubricant to the die but not to a region where the compact slides; a step of supplying the powder into the cavity; a step of orienting the powder in the cavity; a step of pressing the powder in the cavity into the compact; and a step of pushing the compact off the die.
In this invention, since the die lubricant is not applied to the region where the compact is slid, the pushing operation of the compact is not influenced by the die lubricant, and can be performed smoothly.
According to still another aspect of the present invention, there is provided a powder pressing apparatus which presses a powder into a compact in a cavity formed in a die, comprising: powder supply means which supplies the powder into the cavity; orienting means which orients the powder in the cavity, including a pair of yokes sandwiching the die; pressing means which presses the powder in the cavity into the compact; demagnetizing means which demagnetizes the compact and the yokes; and pushing means which pushes the compact off the die.
According to still another aspect of the present invention, there is p
Harada Tsutomu
Kidowaki Shinji
Kohara Seiichi
Armstrong Westerman & Hattori, LLP.
Jenkins Daniel J.
Sumitomo Special Metals Co. Ltd.
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