JPS6126325Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a powder feeding device for a powder compacting machine used for manufacturing sintered machine parts. When molding sintered machine parts, it is necessary to mold the compact so that the green density of each part of the molded body is as uniform as possible. However, a typical powder molding machine pours raw material powder into a cavity formed by a die and a lower punch, fills it with scrapes, and then compresses it between the upper and lower punches.
There is almost no lateral movement during the compression process. Therefore, in order to mold each part to have a uniform density, it is necessary to fill the raw material powder so that the compression ratio (filling depth/height of the molded body) of each part is uniform. For this reason, it is easiest to form the upper punch when its upper end surface is a horizontal plane, that is, when it has a flat plate shape with uniform thickness. Further, even if a certain longitudinal cross section has irregularities, it is possible to mold the shape if it extends straight in a direction perpendicular to the cross section, such as a gutter. In this case, the longitudinal direction and the reciprocating direction of the feed shoe should match, and the required unevenness should be provided on the upper surface of the die and die plate, and on the lower edge of the feed shoe, so that the powder inside the die can be filled by scraping along the unevenness of the lower edge. That's a good translation. However, in the case of a shape that has unevenness on both of its two vertical cross-sections that are perpendicular to each other, for example, a disk shape with a concave center (also called a bowl shape) as shown in Figure 1, , cannot be filled using the method described above. This is because even if a necessary convex portion is provided on the lower edge of the shoe, the shoe itself only moves in one dimension along the upper surface of the die plate. Therefore, conventionally, as shown in Fig. 2, the lower punch 3, which has a concave surface of the desired shape on its upper end, is divided into a plurality of punches by the cut surface of a concentric cylinder, although normally only one punch is required. When filling powder, the inner punch is slightly raised to make the filling depth almost uniform as shown in the diagram, and during molding, the inner punch is returned to its original position and the concave surface at the tip of each punch is fixed in a continuous state. After that, the upper punch 2 is lowered to perform compression molding. However, in this conventional method, not only does the mold become expensive because the lower punch is divided, but it is also necessary to provide the molding machine with a complicated mechanism for individually operating the plurality of lower punches. In addition, it is unavoidable to some extent that some level differences occur at the joints of each punch during molding, which not only impairs the performance or aesthetics of the product, but also causes local distortion in the mold and can lead to mold destruction. There are also problems such as triggering. This invention aims to avoid the above-mentioned problems by enabling uniform forming with a single lower punch.
This goal was achieved by improving the powder feeding device. In other words, the gist of this invention is that instead of providing the necessary convex portion on the lower edge of the feed shoe as described above in the case of a gutter-shaped molded body, the function is separated as a scraper plate, and this scraper plate is placed in front of the feed shoe. It can be raised and lowered freely into the scraping chamber provided in the section.
Alternatively, it is mounted so as to be rotatable within a predetermined angular range by a horizontal rotating shaft, and the powder in the die can be selectively scraped out by two-dimensional movement of the scraping plate. Hereinafter, two embodiments of this invention will be described in detail with reference to the drawings. The molded bodies each had the shape shown in Fig. 1, a diameter of 30 mm, a thickness of 10 mm, and both the upper concave surface and the lower convex surface were spherical with a radius of curvature of 25 mm. First, FIGS. 3 and 4 are examples of a method in which the scraping plate rotates, and the feed shaker 8 reciprocates between the standby position on the left side of the figure and the die 4, and a scraping chamber 9 is provided at the front end of the feed shaker 8. It is different from the conventional one in the following points. A rotating shaft 5 is supported in the chamber 9 in parallel at a height of 21 mm from the die plate in a direction perpendicular to the reciprocating direction of the shoe, and is driven by a rotating device 7. The scraping plate 6 is fixed to the shaft 5, and its lower edge has a radius of curvature of 25
It is shaped like a mm arc. Note that 4 is a die with an inner diameter of 30 mm,
Reference numeral 3 denotes a single lower punch which is slidably fitted with this, and its upper end is a concave spherical surface with a radius of curvature of 25 mm corresponding to the molded body. To describe the operation of this device, first, the scraping plate 6 is held at a position 61 shown by a dotted line, and the shoe 8 is advanced from its standby position to fill the die with powder. At this time, the chamber 9 is located further to the right than in FIG. Next, by retracting the shoe 8 to the position shown in the figure and rotating the scraping plate 6 from position 61 to position 62, the excess powder in the die is scraped out.
A mortar-shaped depression is formed in its wake. The subsequent steps are the same as the normal molding process, and the scraped out powder once retreats together with the shoe and is used for filling in the next cycle. Next, Figure 5 shows an example of the method in which the scraping board moves up and down.
This differs from the above-described rotation method in that a ram 52 that can be raised and lowered is provided in the scraping chamber 9, and a scraping plate 6 is attached to this ram. The means for raising and lowering the ram 52 may be electric, hydraulic, pneumatic, or other arbitrary means, but in this example, a surface cam 53 is provided on the die plate along the reciprocating direction of the shoe.
A method was used in which the ram was engaged with a round shaft 51 extending from the lower end of the ram to the outside of the chamber 9 to mechanically synchronize the forward and backward movement of the shoe and the elevation and descent of the ram. That is, the top surface of the surface cam 53 is designed to maintain a height that does not interfere with the scraping plate 6 while it is on the die plate, and to descend along a predetermined arc only when passing over the die hole. ing. In addition, in order to accurately follow the cam surface,
The scraping board 6 is always pushed downward by a spring. Regarding the operation of this device, the situation in which the shoe 8 advances from the standby position and fills the powder into the die 4 is the same as in the above example. However, during this time,
The scraper moves in and out of the unfilled die, but since there are no obstacles therein, no problem occurs. Next, when the shoe 8 is moved backward, as the chamber 9 passes over the die, the scraping plate 6 moves in and out of the die in a predetermined arc as shown in the figure, leaving a mortar in the place where the excess powder was scraped out. A shaped depression is formed. The subsequent steps and treatment of the scraped-out powder are the same as in the above example, so their explanation will be omitted. Next, using atomized iron powder with a particle size of 100 mesh or less as raw material, setting the filling depth to 25 mm (compression ratio 2.5), and forming a molded body in the shape shown in Figure 1 using each of the above two methods, the molded body Measure the overall density, the partial density of the center and the periphery, and apply the results to the first
Shown in the table. For reference, we tried molding without using a scraping board, but molding was impossible because the compression ratios of each part were significantly different.

[Table] As can be seen from this table, in terms of uniformity of the partial density of the compact, the rake plate rotation method showed better results, but this is due to the influence of the angle at which the rake plate is finally scraped. Conceivable. 〓〓〓〓
However, in terms of forming efficiency, the raising and lowering method of the scraping board is superior, and the latter method is considered to be the only method when the scraping board requires complicated movements other than circular arcs.

[Brief explanation of the drawing]

Fig. 1 is a drawing illustrating the shape of the molded object that is the object of this invention, Fig. 2 is a drawing illustrating a conventional method for molding it, and Figs. 3 and 4 are drawings illustrating an embodiment of this invention. , FIG. 5 is a drawing showing another embodiment. 2... Upper punch, 3... Lower punch, 4... Die, 6... Scraping board, 7... Scraping board rotation device, 8
...Feeder, 9...Scraping room, 53...Scraping board lifting device. 〓〓〓〓

Claims (1)

[Scope of utility model registration request] A bottomless scraping chamber 9 is provided at the front of the feed shoe 8, and within this chamber a scraping plate 6 whose lower edge is formed into a desired shape can be raised and lowered or rotated within a predetermined angle range using a horizontal rotating shaft. A powder feeding device for a powder molding machine characterized by being freely attached.