JP2003334700A - Powder compacting apparatus and powder compacting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder compacting method capable of compression- molding a powder compact having a plurality of pores in which the inside is partitioned by a thin partition wall, so soundly that a crack or other defects are prevented from occurring in sintering the compact. <P>SOLUTION: A powder compacting apparatus consists of a die 2 provided with a die hole 20, a fixed punch 3 to be inserted into the die hole 20 from the lower portion of the die 2, a floating punch 4 to be inserted into a punch hole of the punch 3 from the lower portion of the punch 3 and stopped by a stopper 8 so as not to descend, and an upper punch 3 to be inserted into the die hole 20 from the upper portion of the die 2. Also, the apparatus includes an elastic energizing means 5 fixed on the upper punch 3 so as to be pressed and moved downward, a depressing rod 6 connected to the means 5 to extend downward, and a holding rod 7 arranged so as to be fixed on the punch 4 so that its upper end can abut on the lower end of the rod 6. The timing of abutting of the rod 6 on the rod 7 is adjustable. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a powder molding apparatus and a molding method for molding a powder molded body, and in particular,
The present invention relates to a powder molding apparatus for a powder molded body having a gap and a thin wall portion inside and a molding method thereof.

[0002]

2. Description of the Related Art A powder molding apparatus for molding a powder molded body having a narrow gap inside and a thin wall portion between the gaps from a powder is known, for example, as shown in FIGS. An example thereof is shown in Fig. 1, in which the powder molding apparatus includes a die 2 having a die hole 20 forming a side surface of the powder molded body, and an upper punch 1 inserted in the die hole 20 above the die in a hydraulic machine. It is connected. The apparatus further includes, below the die 2, a fixed punch 3 which is inserted into the die hole 20 from below, and a floating punch 4 which is inserted into the punch hole of the fixed punch 3 from below the fixed punch. . The upper end surface 40 of the floating punch 4 has a predetermined shape for molding a part of the powder compact. The support member 41 of the floating punch 4 is elastically biased upward by a spring or an air cylinder, and the support member 41 is provided with a stopper 8 that abuts the lower surface of the support member and restricts its descending to stop. It is provided.

At the time of powder molding, as shown in FIG.
With the fixed punch 3 inserted in the die hole 20 and the floating punch 4 inserted in the punch hole, the upper punch 1 is retracted upward, and the powder 9a is filled in the die hole 20. Then, Fig. 8
As shown in (B), the upper punch 1 is inserted into the die hole 20, and the powder 9a is compressed while being pressed and lowered by the cylinder of the hydraulic machine. Since it remains fixed, as shown in FIG. 8C, when the floating punch 4 descends and comes into contact with the stopper 8 to stop the descending, the upper punch 1 is further pressed until it reaches the bottom dead point, and the desired result is obtained. The shaped molded body 9 is formed. After that, the powder is released from the mold and taken out from the powder molding device as a powder molded body.

[0004]

An example of the powder molded body 9 is shown in FIG. 4. The molded body has a rectangular parallelepiped outer shape, and in this example, there are five parallel rows of gaps. 9
3 is formed so as to penetrate vertically, and a thin wall 94 made of compressed powder is formed between the gaps. In this example, the gap 93 is tapered from one surface side to the other surface side of the molded body. Such a powder molded body was molded from the powder of the ceramic material in the above-described manner and fired to obtain a sintered body.

However, when a powder compact having the above-mentioned shape is manufactured by the above-mentioned conventional apparatus, a crack is often generated in the sintered body when firing, and the sintered body is sometimes broken. This is because in the case of compression molding, when the gap 93 is formed by the floating punch, the vicinity of the taper upper portion 92 of the gap is formed.
When the powder of a and the powder of the taper lower portion 92b have a density difference and such a molded body is fired, a difference in local shrinkage amount of the sintered body due to sintering causes a difference in the sintered body. This is because cracks occur in the. Further, even in the thin wall, a difference in the compression density of the powder occurs, and cracks may occur in the sintered thin wall.

In view of the above problems, the present invention is capable of soundly compacting a powder compact having a plurality of gaps whose interior is divided by thin partition walls so as to prevent cracking and other defects during sintering. It is intended to provide a molding device. The present invention further provides a powder molding method capable of soundly compression molding a powder molded body having a plurality of gaps divided by a thin partition wall so that cracks and other defects do not occur during sintering. It is a thing.

[0007]

The powder molding apparatus of the present invention comprises a die having a die hole, a fixed punch inserted into the die hole from below the die, and a fixed punch in the punch hole of the fixed punch. It consists of a floating punch that is inserted from below the die and an upper punch that is inserted into the die hole from above the die.The feature is that the above device is fixed to the upper punch and pushed downward. An elastic urging means capable of advancing, a push-down rod connected to the elastic urging means and extending downward, and a holding rod arranged so that the lower end of the push-down rod can abut against the lower end of the floating punch. In addition, the floating punch is forcibly lowered by the contact between the push-down rod and the holding rod when the die is lowered.

The powder molding method of the present invention includes a method of molding a powder molded body by the above-mentioned apparatus, including a die having a die hole, a fixed punch inserted into the die hole from below the die, and the fixed die. Powder is molded by a floating punch that is inserted into the punch hole of the punch from below the fixed punch, and an upper punch that is inserted into the die hole from above the die. Place it in the die hole,
The step of filling powder in the die hole, the step of inserting the upper punch into the die hole and lowering it with the lifting device to pressurize the powder, and then the elastic fixed to the upper punch as the upper punch is pushed down. A step in which the push-down bar pressed by the biasing means abuts on a holding bar connected to the floating punch, and the floating punch is forcibly lowered via the holding bar; And then stopped, and then the powder is finally pressed into a powder compact having a predetermined shape by pressing down the upper punch.

The apparatus and method of the present invention can be applied particularly to a powder molded body having a plurality of gaps whose inside is divided by thin partition walls. With respect to such a powder molded body, in the apparatus and method of the present invention, since the timing of contact between the push-down bar and the holding bar when the die is lowered can be adjusted, the contact timing can be advanced. If the start of the forced lowering of the floating punch during the die lowering is accelerated, the compression density of the powder around the gap formed by the floating punch can be made relatively low, while the contact timing is delayed to lower the die. If the start of the forced lowering of the floating punch is delayed at times, the compression density of the powder around the gap formed by the floating punch can be made relatively high. The apparatus of the present invention utilizes this property to appropriately adjust the timing of this contact, thereby making the compression densities inside the powder compact and in the vicinity of the gap uniform.

In the present invention, as the floating punch, a floating punch having a predetermined shape for molding a plurality of gaps in the powder compact is formed on the upper end surface of the floating punch. Compressed density of powder by measuring the timing of contact between the pressing rod and the holding rod when lowering the upper punch of a powder molded body that has a plurality of narrow gaps partitioned by multiple thin walls inside Can be manufactured uniformly. In particular, if the protrusion has a tapered taper or trapezoidal shape, the compression density of the peripheral powder on the front side and the root side of the tapered or trapezoidal gap is made uniform by measuring the timing of contact. be able to.

The present invention preferably comprises a timing adjusting mechanism for adjusting the timing of contact between the push-down rod and the holding rod. For such a mechanism, it is adopted to include an adjusting screw engraved on the lower part of the holding rod connected to the floating punch, screwed and fixed to the support of the floating punch, and adjusting the height position of the upper end of the holding rod. it can. By adjusting the height position of the upper end of the holding rod via this adjusting screw, the timing at which the push-down rod contacts the holding rod can be adjusted, and this can change the timing at which the floating punch is forced to descend. it can.

The elastic biasing means is fixed to the upper punch,
The upper punch that supports the push-down bar downward and elastically urges the holding bar downward when it abuts the upper end of the holding bar to push down the floating punch, and further lowers when the floating punch is stopped by the stopper. With respect to this, the push-down bar is displaced relative to the upper side to let it escape. A spring, for example, a coil spring can be used for such elastic biasing means. At this time, the coil spring is connected to the pressing rod. An air cylinder can also be used as the elastic biasing means, and at this time, the piston of the air cylinder is connected to the push-down rod.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In this embodiment, an example of an apparatus for molding a powder compact having a plurality of gaps partitioned by a partition wall, that is, a thin wall 94 inside, and a molding method by this apparatus is illustrated. 1 to 3 show. Powder molding equipment,
Die 2 with die hole 20 that forms the side of the powder compact
Is fixed to the device body. Below the die 2, a fixed punch 3 which is inserted into the die hole 20 from below and a floating punch 4 which is inserted into the punch hole of the fixed punch 3 from below the fixed punch 3 are arranged.

The lower portion of the fixed punch 3 is fixed to the main body of the apparatus, and the upper surface of the fixed punch 3 forms the lower surface of the powder compact. The fixed punch 3 has a through hole through which the front side of the floating punch 4 can be inserted. Is equipped with.

The floating punch 4 is fixed to a vertically movable floating punch support 41, and the lower portion thereof is supported by a hydraulic punch or other floating punch urging device (not shown) capable of elastically urging upwards, and the fixed punch 3 is fixed. The projection piece 44 of the tip end surface 40 of the floating punch 4 forms a gap 93 in the molded body 9 by being inserted into the through hole of the. Further, the apparatus main body is provided with a stopper 8 below the floating punch 4 for stopping the lowering of the floating punch 4 and defining the lower limit of the floating punch support body 41.

An upper punch 1 which is inserted into a die hole 20 is arranged above the die 2 of the powder molding apparatus, and the lower surface of the upper punch 1 molds the upper surface of the molded body and supports the upper punch. Via the upper punch support 12, a hydraulic device,
It is supported by a lifting device (not shown) that can be pressed downward.

The above-mentioned apparatus comprises, as the elastic biasing means, an air cylinder 5 fixed to the upper punch 1 and a downward pushing rod 6 connected to a piston 51 of the air cylinder 5, When the push-down bar 6 descends, the push-down bar 6 is arranged so as to be able to contact the fixing member fixed to the floating punch 4,
The relative distance between the upper punch 1 and the floating punch 4 is determined.
In one embodiment, the floating punch 4 includes a holding rod 7 which is arranged such that an upper end 70 is fixed to the lower end 60 of the push-down rod 6 such that the upper end 70 can abut.

More specifically, in this embodiment, the upper punch 1 fixes the air cylinder 5 to the upper punch support 12, and the air cylinder 5 has a downwardly extending push-down rod 6 connected to its piston 51. Have Air cylinder 5
An air pipe for pressurizing the cylinder empty chamber 5a on the upper side of the piston 51 is connected in the inside thereof, and constantly pressurizes the cylinder empty chamber 5a and presses the push-down bar 6 downward.

On the other floating punch 4, a holding rod 7 is erected upward from the floating punch support body 41 that supports the floating punch 4. The holding rod 7 has its upper end 70 at the above-mentioned push-down rod. It is arranged so as to contact the lower end 60 of the push-down rod 6 when the push-down rod 6 descends. In this way, when the upper punch 1 is lowered, the relative positions of the upper punch 1 and the floating punch 4 can be accurately determined by the contact between the ends of the upper and lower push-down rods 6 and the holding rod 7.

The advantage of providing the holding rods 7 is that by using the holding rods 7 having different lengths, when the upper punch 1 is lowered in the molding process, the upper and lower push-down rods 6 and the holding rods 7 come into contact with each other. It is possible to change the timing. For this purpose, as shown in FIGS. 1 to 3, an adjusting screw 71 for screwing the holding rod 7 into the floating punch support body 41 is provided.
It is preferable that the holding rod height can be changed by changing the screwing depth of the adjusting screw 71. It is preferable that two or more sets of the timing adjusting mechanism composed of the cylinder 5, the push-down rod 6 and the holding rod 7 are provided at symmetrical positions with respect to the die center axis, for example.

In powder molding, in FIG. 1, the upper punch 1 is retracted upward, and the fixed punch 3 and the floating punch 4 are moved.
Are placed in the die hole 20, the die hole 20 is scrubbed and filled with the powder 9a, and the upper punch 1 is inserted into the die hole 20 and lowered by an elevating device to press the powder.

Then, as the upper punch 1 is pushed down,
As shown in FIG. 2, the push-down rod 6 pressed by the air cylinder 5 contacts the holding rod 7, and the floating punch 4 is forcibly lowered via the holding rod 7. Then, as shown in FIG. 3, in the floating punch 4, the floating punch support 41 has a stopper 8
Even after being abutted against and stopped, the powder 9a is finally pressed by pressing down the upper punch 1 to form a powder compact 9b (9) having a predetermined size and shape. In the final pressurization process, the holding rod 7 stops and the vacant chamber 5a of the cylinder contracts, so that the push-down rod 6 can be displaced upward and escape.

By the powder molding apparatus and the powder molding method of this embodiment, as shown in FIGS. 4 to 6, a plurality of tapered gaps 93 vertically penetrating the powder compact 9 and a thin wall 94 partitioning the gaps are formed. The molded body 9 can be molded.
In this case, the push-down rod 6 and the holding rod 7 are the same as the upper punch 1
When the compression density of the powder on the taper upper portion 92a is still low during the descending process of the floating punch 4a, the floating punch 4 is adjusted.
If the timing of the forced lowering is measured, the compression densities of the powder in the taper upper portion 92a and the taper lower portion 92b can be made uniform in the powder near the gap in the cross-sectional views shown in FIGS. This is because the taper upper part 92a is the floating punch 4
And the taper lower portion 92b is forced to descend and the powder raw material of the thin wall 94 flows in and is filled in the taper lower portion 92b, and the taper lower portion 92b stops like the taper upper portion 92a. , Because the density becomes a predetermined value.

On the other hand, in the above powder compact, the pressing rod 6 and the holding rod 7 are brought into contact with each other when the compression density of the powder in the taper upper portion 92a becomes high during the lowering process of the upper punch 1. By adjusting and delaying the timing of the forced lowering, the compression density of the powder in the thin walls 94, 94 between the gaps 93, 93 can be increased. The reason is that the powder raw material on the thin wall 94 is compression molded without escaping in the direction of the taper upper part 92a and the taper lower part 92b.

In this way, the timing of the forced lowering of the floating punch 4 is adjusted by adjusting the timing of contact between the push-down rod 6 and the holding rod 7 to provide a uniform and dense gap. Powder compacts can be made.

The powder molding apparatus and powder molding method of the present invention are
It can be widely applied to powder compacts having a plurality of gaps inside the compact and thin walls between the gaps. Such a powder molded body is used, for example, as a flow path component that allows a fluid such as ink to flow in the gap, or a component such as an electrode spacer or an electrode support component that buries and fixes the electrode in the gap. Further, the raw material of the powder to be molded, the powder of ceramic raw material such as alumina, aluminum nitride, silicon nitride, silicon carbide, mullite, steatite, forsterite,
Metal and alloy powders are included.

[0027]

EXAMPLE A powder compact shown in FIG. 4 to FIG.
0 to 150 μm Molded from alumina powder having a distribution of The outer shape of the powder compact is 20 x 30 x 50 mm.
The inside of the rectangular parallelepiped has a gap 93 arranged in five layers partitioned by thin walls 94. The gap 93 penetrates in the thickness direction of the rectangular parallelepiped of the molded body 99, and the length of the lower opening 93b is 12 mm, and the upper opening is 93 mm. The length of 93a is 2 mm, and the thickness 93c of the gap is tapered to 0.400 mm. The thin wall 94 for partitioning the gap has a thin wall thickness 94c of 0.600.
It was set to mm.

The powder molding apparatus used in this embodiment has the above-described structure shown in FIG. 1, and the upper end surface 40 of the floating punch 4 is
Corresponding to the shape of the gap 93 of the above five layers of the powder molded body, 5
It is provided with a trapezoidal protruding piece 44 having a protruding layer. Holding rod 7
Is adjusted by adjusting screw 71 on the lower end side and screwed into a screw hole 42 provided in the floating punch support body 41 to adjust the height of the holding rod 7 to lower the upper punch. so,
The timing of contact between the lower end 60 of the push-down rod 6 and the upper end 70 of the holding rod 7 was adjusted.

The test was carried out using the same floating punch, and the adjustment of the timing at which the push-down rod 6 abuts the holding rod 7 was adjusted immediately after the upper punch 1 was inserted into the die hole (timing A). Abutting at an intermediate position after the upper punch 1 is inserted into the die hole until the bottom dead center (timing B), and the upper punch 1
Are three levels of contact (timing C) at the position just above the bottom dead center,
I did.

The molded sample was preheated at 1400 ° C.
The sintered body was calcined for 12 hours to obtain a sintered body, and the gap thickness and the thin wall thickness of the sintered body were measured at the lower opening of the gap, and the average value was obtained. Further, after the color check liquid was applied to the sintered body and penetrated, cracks in the thin wall were visually observed. The test results are summarized in Table 1.

As a comparative example, molding was carried out under the same conditions as in Example except that the push-down rod and the holding rod were not used.
Similarly, after firing, the sample was subjected to dimension measurement and crack observation.

[0032]

[Table 1]

The results of the test are shown in Table 1. In the molding of the powder compact having the above-mentioned gap size, the gap thickness and the thinness can be reduced by setting the contact timing at the intermediate position between the die hole entrance and the bottom dead center at the timing B. The wall thickness also showed the closest value to the set value, and no cracks occurred. Therefore, by adjusting the timing of the start of the floating punch descent, the powder compact was almost uniform, especially in the upper taper part and the lower taper part. It can be seen that it was possible to realize a uniform compressed density distribution and also to achieve uniformized compressed density distribution in the thin wall portion.

[0034]

According to the powder molding apparatus of the present invention, the elastic urging means for supporting the upper punch, the downwardly extending push-down rod connected to the elastic urging means, and the lower end of the push-down rod contact the upper end. Including a holding rod that is fixed to the floating punch so that it can touch, the timing of contact between the push rod and the holding rod when the die is lowered can be adjusted, so it can be used to lower the upper punch. It is possible to regulate the compression density of the powder around the gap to be formed by the floating punch by specifying the timing for forcibly lowering the floating punch, and to make a powder compact having a uniform density distribution. it can.

In the powder molding method of the present invention, the fixed punch and the floating punch are arranged in the die hole, the step of filling the die hole with powder and the step of inserting the upper punch into the die hole and lowering them by the elevating device. After the step of pressurizing the powder by pressing the powder, the pressing rod pressed by the elastic biasing means fixed to the upper punch comes into contact with the holding rod connected to the floating punch as the upper punch is pressed down, The floating punch is forcibly lowered via the holding rod, and after the floating punch is stopped by the floating punch support body contacting the stopper, the powder is finally applied to the powder compact of a predetermined shape by pushing down the upper punch. Since the pressure is applied, the timing or timing for forcibly lowering the floating punch in response to the lowering of the upper punch during powder molding is specified to adjust the compression density of the powder around the gap to be formed by the floating punch. Plan Bets can be, it is possible to make a powder molded body having a uniform density distribution.

According to the apparatus and the manufacturing method of the present invention, if the floating punch has, on the upper end surface of the floating punch, a protrusion having a predetermined shape for molding a plurality of gaps in the powder molded body, It is possible to produce a powder molded body in which the compression density of the powder in the peripheral portion is made uniform.

If the holding rod includes an adjusting screw that is screwed and fixed to the support of the floating punch and that adjusts the height position of the upper end of the holding rod, the timing for starting the forced lowering of the floating punch can be adjusted. It is possible to adjust the optimum timing for starting the forced lowering of the floating punch each time the particle attributes such as the shape of the powder compact, the material / type of powder, and the particle size distribution of powder are changed.

If the elastic biasing means is an air cylinder and the piston of the air cylinder is connected to the push-down rod, the downward load of the floating punch and the pressure thereof as the upper punch descends. Adjustment is easy, and after the floating punch is stopped by the stopper, the final pressurization by the upper punch to the bottom dead center can be surely performed on the molded body.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a powder molding apparatus according to an embodiment of the present invention, showing an arrangement immediately after filling powder in a die hole in a powder molding process.

FIG. 2 is a cross-sectional view of the powder molding apparatus according to the embodiment of the present invention, showing the arrangement at the time when the upper punch starts compressing the powder in the powder molding step and the floating punch subsequently starts to descend.

FIG. 3 is a cross-sectional view of a powder molding apparatus according to an embodiment of the present invention, showing an arrangement in which a floating punch is stopped by a stopper and a top punch reaches a bottom dead center for final pressing in a powder molding process. .

FIG. 4 shows a perspective view of a powder compact molded according to an embodiment of the present invention.

FIG. 5 shows a cross-sectional view of a powder compact molded according to an embodiment of the present invention.

FIG. 6 shows a cross-sectional view of a powder compact molded according to an embodiment of the present invention.

FIG. 7 shows a perspective view of an upper end surface of a floating punch used in the powder molding apparatus of the present invention.

FIG. 8 is a cross-sectional view of a conventional powder molding apparatus, in which (A) is a powder filling process, (B) is an initial pressing process by the upper punch, and (C) is a final pressing process by the upper punch. The arrangement is shown respectively.

[Explanation of symbols]

1 upper punch Two dies 20 die holes 3 fixed punch 4 floating punch 41 Floating punch support 5 Air cylinder 6 push rod 7 holding rod 8 stopper 9a powder 9 powder compacts 93 gap 94 thin wall

Claims (9)

[Claims] 1. A die having a die hole, a fixed punch inserted into the die hole from below the die, a floating punch inserted into the punch hole of the fixed punch from below the fixed punch and stopped descending by a stopper. A powder molding apparatus comprising a punch and an upper punch that is inserted into the die hole from above the die, wherein the above-mentioned apparatus is fixed to the upper punch and is elastically urged downward, and the elastic biasing means is provided. A push-down rod connected to the biasing means and extending downward; and a holding rod fixed to the floating punch so that the upper end can abut the lower end of the push-down rod. A powder molding apparatus characterized in that a floating punch is forcibly lowered by contact with a holding rod. 2. The powder molding apparatus according to claim 1, wherein the floating punch is provided with a protrusion having a predetermined shape for molding a plurality of gaps in the powder molded body on an upper end surface of the floating punch. 3. A timing adjusting mechanism for adjusting the timing of contact between the push-down rod and the holding rod.
The powder molding apparatus according to 1. 4. The powder molding apparatus according to claim 3, wherein the timing adjusting mechanism includes an adjusting screw for screwing and fixing the holding rod to the support of the floating punch and adjusting the height position of the upper end of the holding rod. 5. The powder molding apparatus according to claim 1, wherein the elastic biasing means is an air cylinder, and a piston of the air cylinder is connected to the push-down rod. 6. A die having a die hole, a fixed punch inserted into the die hole from below the die, a fixed punch inserted into the punch hole of the fixed punch from below the fixed punch, and stopped descending by a stopper. A method of molding powder by a floating punch and an upper punch that is inserted into the die hole from above the die, wherein a fixed punch and a floating punch are arranged in the die hole, and the die hole is filled with the powder. And the step of inserting the upper punch into the die hole and lowering it by the elevating device so that the upper punch pressurizes the powder. Then, as the upper punch is pushed down, the elastic biasing means fixed to the upper punch applies the force. The pressed down rod abuts the holding rod connected to the floating punch, and through the holding rod,
A step of forcibly lowering the floating punch, and a step of finally pressing the powder into a powder compact of a predetermined shape by pushing down the upper punch after the floating punch is stopped by contact with the stopper of the floating punch support. A powder molding method comprising: 7. The powder molding method according to claim 6, wherein the floating punch is provided with a protrusion having a predetermined shape for molding a plurality of gaps in the powder molded body on the upper end surface of the floating punch. 8. A timing adjusting mechanism for adjusting the timing of contact between the push-down rod and the holding rod.
The powder molding method according to. 9. The powder molding method according to claim 6, wherein the elastic biasing means is an air cylinder, and a piston of the air cylinder is connected to the push-down rod.