JP3984355B2 - Powder filling method and powder feeder feeder in powder molding press - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a raw material powder filling method and a powder feeding apparatus in a powder molding press mainly used in the fields of powder metallurgy, ceramics, etc., and particularly to a feeder thereof.
[0002]
[Prior art]
In general, a powder molding press is filled with raw material powder from a powder feeding device in a die cavity formed by a die 40 attached to a die plate 30 and a lower punch 50 fitted to the die, and the powder in the die is added to Compression molding is performed between the lower punches, and the powder feeding device is normally connected to a hopper 60 which is elevated and stores raw material powder and a box-like feeder 10 without a bottom by a flexible hose 61 as illustrated in FIG. It has a configuration. The feeder first advances from its standby position toward the die (to the left in the figure), reaches the top of the die 40, flows the raw material powder, and then flattens the upper surface of the powder deposited in the die at the lower edge of the feeder. Thus, it is moved back to the standby position while being scraped off to complete one cycle of filling. Reference numeral 11 in the figure denotes a drive rod that is connected to a drive device (not shown) such as a hydraulic cylinder to advance and retract the feeder.
[0003]
When filling powder into the die from the feeder, a drop-in method is generally used. As shown in FIG. 8 (a), the lower punch 50 is lowered to a predetermined filling depth in advance (or the die 40 is raised). A die cavity is formed, and the feeder is moved on the die cavity and filled by free fall of the powder. In this case, the feeder is often vibrated several times back and forth on the die to facilitate the fall of the powder.
[0004]
Another method is a suction filling method used when the die cavity is narrow or deep and sufficient filling cannot be achieved by dropping, and the feeder is moved over the die in advance as shown in FIG. Next, the lower punch 50 is lowered (or the die 40 is raised) to a predetermined filling depth, and the powder is sucked and filled from the feeder while forming the die cavity.
[0005]
[Problems to be solved by the invention]
Regardless of the powder filling method described above, when the die cavity is filled with powder, the state shown in FIG. When the feeder 10 is moved backward from this state, the feeder returns to the standby position while scraping the powder in the die 40 flatly at its front edge 12 as shown in FIG. At that time, the powder on the surface layer portion in the die is dragged by the movement of the feeder (and the powder therein) and moves in the backward direction of the feeder, that is, toward the standby position of the feeder.
[0006]
FIG. 6 schematically shows the situation with some emphasis, and in the powder filling state of (A), the powder in the surface layer portion is densely deposited on the inner wall of the die on the standby position side, and on the opposite side, It is away from the inner wall of the die. Therefore, when compression molding is performed in this state, as shown in (b), a green compact having a high density on the standby position side in the die and a low density on the opposite side (feeder advance direction) is formed. Such non-uniform density occurs more markedly when the packing depth is shallow and the resulting green compact is thin, resulting in warping and distortion during sintering, strength of the sintered product, etc. There was a problem of inhomogeneous mechanical properties, uneven center of gravity and various other defects. In addition, such a powder deviation phenomenon is more remarkable when the powder filling depth is extremely shallow. In the cavity in the forward direction of the feeder (the left side in the figure), the powder that has been filled is dragged back by the feeder and returned. It may not be filled.
[0007]
[Means for Solving the Problems]
The reason why the above-mentioned deviation occurs in the powder (on the surface layer) in the die when the feeder is retracted is considered to be abraded in a state where a large amount of powder in the feeder is loaded. As a result, if the powder deposited on the die is reduced prior to scraping at a predetermined filling depth and the load on the surface layer is reduced and then scraped, the powder accompanying the scraping is reduced. The deviation will be eliminated.
[0008]
The present invention has been made on the basis of such an idea. Conventionally, the front edge 12 which has been integrated with the feeder main body and is always in contact with the die plate 30 can be separated and moved up and down, and its lower end and the lower edge of the feeder. A scraper that has a structure that can arbitrarily set a gap with (the upper surface of the die plate 30) and that can arbitrarily adjust the gap between the lower edge of the feeder and the upper surface of the die plate. 21 is provided with a fraying device 20 having 21. The functions of the leading edge 12 and scraper 21 will be described later with reference to FIGS.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1) FIG. 1 shows an embodiment of a feeder according to the present invention. As shown in FIG. 1 (a), a front edge 12 that is conventionally integrated with a feeder body 10 is separated. The structure is configured to be freely movable up and down and to be fixed by arbitrarily setting a gap between the lower end thereof and the lower edge of the feeder (the upper end surface of the die plate 30). Accordingly, the lower portion of the front surface of the feeder is opened by the gap. A support frame 22 is provided on the front surface of the feeder, and two scrapers 21 are attached to the support frame so that the gap between the die plate and the die plate can be arbitrarily adjusted. In addition, (b) of the figure is a perspective view of the feeder main body 10 viewed from the front without the scraper plate 21 and the like, and the front edge 12 is fixed at a predetermined position by a set screw 13. The drive rod 11 is drawn to show the orientation of the feeder, but the flexible hose 61 is omitted.
[0010]
For convenience of explanation, when the scraper plate 211 is the tip of the feeder body and the scraper plates 212, 213... Between the leading edge 12 and the leading edge 12, the gap between the leading edge 12 and the die plate is larger than a predetermined filling depth. Also, the clearance between the scraping plate 21 and the die plate is adjusted to be equal to a predetermined filling depth in the tip scraping plate 211 and gradually increased in the intermediate scraping plates 212. That is, in this feeder, first, the front edge 12 is scraped off leaving a little more powder than the predetermined filling depth, and then the scraping plate 21 is scraped off so that the plate is scraped off with a scissors, for example. It finishes to the depth. Therefore, it is preferable that the lower end of the lower end is a knife edge and is inclined toward the feeder side (to the front edge 12 side) so as to be suitable for such purposes. Incidentally, the scraper 211 at the tip is indispensable, but the intermediate scraper 212 may be omitted, or two (two stages) or more may be required.
[0011]
(Embodiment 2) FIG. 2 shows a case where the feeder according to the present invention is applied to the drop-filling method. In FIG. 2 (a), the feeder 10 advanced from the standby position reaches the die 40 and reaches the die 40. The state filled with powder is shown. Since a predetermined gap is provided between the front edge 12 and the die plate 30, a part of the powder in the feeder leaks forward from this gap. If a plane parallel to the die plate 30 passing through the lower end of the leading edge 12 is assumed here, the powder above the virtual plane returns together with the feeder when the feeder is retracted, and the powder below the virtual plane is the same as the gap. A layer of thickness is left on the die and the effect of chafing by the leading edge 12 is received by this layer to prevent direct application to the powder in the die. On the other hand, since the intermediate scraper 212 can be reduced as the amount left in the scraping device 20 is smaller, it is preferable to set the size of the gap as small as possible within the range in which the above-described prevention effect is effective.
[0012]
When the feeder is retracted from the state shown in (a) in the figure, as shown in (b), the intermediate scraper 212 first scrapes off a part of the powder left on the front edge 12 on the die. The remaining powder is scraped off by the scraper 211 at the tip, but since the thickness is small, the powder in the die is not affected. Thus, precise fraying and filling is completed without causing the powder bias associated with fraying as in the prior art. Instead of individually adjusting the gaps of the scraping plates, the support frame 22 can be attached to the feeder with a hinge and adjusted at once by changing the angle.
[0013]
(Example 3) Next, FIG. 3 shows an example in which the feeder according to the present invention is applied to suction filling in the case of a molded product having a small thickness. (B) in the figure is the same as (b) in FIG. 8 for explaining the suction filling, in which the feeder 10 is advanced (strictly, its leading edge 12) to the front of the die 40 slightly before the die cavity is formed. Thus, the gap between the leading edge 12 and the die plate is set to be slightly larger than the predetermined filling depth. Further, in this example, the scraping device 20 is provided with two scrapers 21, but the gap between the scraper and the die plate is somewhat smaller than the gap of the front edge 12 at the intermediate scraper 212, The scraping plate 211 is adjusted to be equal to a predetermined filling depth.
[0014]
When the feeder is retracted from this state, as shown in (b), the powder in the feeder flows out from the gap between the front edges 12 in a layer slightly thicker than the predetermined filling depth. Subsequently, an intermediate scraper 212 is scraped off the surface of this layer, and finally the scraper 211 at the tip is scraped to a thickness equal to a predetermined filling depth. Thus, a powder layer having a predetermined thickness is formed on the die 40 and the die plate 30 before and after the die 40. This layer is formed by scraping step by step and is continuous. This partial bias does not occur. If the lower punch 50 is lowered (or the die 40 is raised), the powder on the lower punch moves as it is into the die as shown in (c), and suction filling with a uniform and predetermined filling depth is completed. To do. In this filling method, even when the thickness is small, uniform and precise filling is possible, so that it can be used for molding ceramic parts of semiconductor devices, for example.
[0015]
In the case of this method, the feeder is provided with an appropriate tilting means, for example, a means for adjusting the outer frame 14 fitted to the feeder 10 with an adjusting screw 15 as shown in FIG. As a result, a powder layer whose thickness is continuously changed is obtained. Therefore, if the product is sucked and filled as it is, a functionally graded product in which the density, the accompanying strength, the impregnation rate, and other properties are continuously changed can be obtained. Further, if the adjusting screw 15 is adjusted to incline the feeder forward, the gap between the leading edge 12 and the scraper plate 21 and the die plate can be reduced. Therefore, these gaps can be roughly set in advance and finely adjusted with the adjusting screw 15.
[0016]
The embodiment shown in FIGS. 1 to 4 is an embodiment in which the gap between the leading edge 12 and the scraping plate 21 is adjusted by moving the leading edge 12 and the scraping plate 21 up and down. It is also possible to provide a shaft, attach this shaft to the side wall of the feeder or support frame 20 so as to be swingable, incline so that the gap with the die plate has a predetermined size, and fix with a nut or the like. Moreover, although the scraper 21 showed the Example of the aspect attached to the support frame 20 provided ahead of the feeder 10, the front edge was removed from the conventional feeder, and it corresponds to the front edge 12 of an Example in it. A scraper and scrapers 211, 212,... May be arranged.
[0017]
【The invention's effect】
As described in detail above, according to the present invention, the deviation of the powder in the die due to the fraying of the feeder is eliminated, and uniform and precise molding with no bias even when the product is thick or thin Goods can be obtained.
[Brief description of the drawings]
FIG. 1 is a drawing for explaining an embodiment of a feeder according to the present invention.
FIG. 2 is a diagram for explaining a usage mode of a feeder in Embodiment 2 of the present invention.
FIG. 3 is a view for explaining a use mode of a feeder in Embodiment 2 of the present invention.
FIG. 4 is a diagram illustrating a mode in which a feeder is tilted left and right.
FIG. 5 is a diagram for explaining problems of a conventional feeder.
FIG. 6 is a schematic diagram for explaining a state in which the powder in the die is offset by a conventional feeder and a state in which the powder is compression-molded.
FIG. 7 is a diagram illustrating a general configuration of a powder feeding apparatus in a powder molding press.
FIG. 8 is a diagram for explaining a dropping method and a sucking method in powder filling.
[Explanation of symbols]
10 ... Feeder, 11 ... Drive rod, 12 ... Lead edge, 30 ... Die plate,
40 ... Die, 50 ... Lower punch, 60 ... Hopper, 61 ... Flexible hose,
13 ... set screw, 20 ... scraping device, 21 ... scraper, 22 ... support frame,
14 ... outer frame, 15 ... adjusting screw, 70 ... upper punch.

Claims (8)

  At least two stages of powder scraping when retreating by a bottomless box-shaped feeder that advances and retreats on the die plate of a powder forming press, and the powder supplied on the die in the first stage is slightly thicker than a predetermined filling depth A powder molding press characterized in that it is leaked out of the feeder so as to remain, and is scraped off, and the remaining powder is scraped to a predetermined filling depth in the second stage or the final stage, so that the powder is uniformly filled in the die. Powder filling method.   The lower punch 50 is raised to the surface of the die plate in advance, a powder layer having a thickness equal to a predetermined filling depth is formed on the die plate and the lower punch, and then the lower punch 50 is lowered and placed thereon. The powder filling method according to claim 1, wherein the deposited powder is transferred into a die.   In a box-shaped feeder having a bottom where the front edge 12 advances and retreats from the standby position to the other side of the die 40 on the die plate of the powder molding press, the front edge 12 is separated from the feeder body and freely movable up and down. And a structure in which the gap between the die plate and the die plate can be arbitrarily set, a scraping plate 21 is provided in front of the front edge 12, and the gap between the front edge 12 and the die plate is set slightly thicker than a predetermined filling depth A feeder for a powder feeder in a powder molding press, wherein a gap between the scraper plate 21 and the die plate is adjusted to a predetermined filling depth.   The scraper plate 21 is composed of one tip scraper plate 211 and at least one intermediate scraper plate 212. The gap between the intermediate scraper plate 212 and the die plate is intermediate between the leading edge 12 and the tip scraper plate 211. The feeder of the powder feeding apparatus of Claim 3 adjusted to the magnitude | size.   The feeder of the powder feeding apparatus of Claim 3 or Claim 4 in which the lower end of the scraper plate has a knife edge shape and is inclined toward the feeder side.   The feeder of the powder feeding apparatus according to claim 3, wherein the front edge 12 and the scraper plate 21 of the feeder can variably set the gap between each lower end and the die plate to an arbitrary size.   The variable means of the gap between the front edge 12 of the feeder and the die plate of the scraper plate 21 moves the front edge 12 and the scraper plate 21 up and down or swings with each upper end as a rotation axis. Feeder for powder feeder.   The feeder of the powder feeding apparatus according to claim 3, further comprising means for inclining the feeder in its advancing / retreating direction or laterally.

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