JP2006187793A - Powder molding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder molding device capable of molding a green compact having excellent height accuracy. <P>SOLUTION: In the powder molding device, a plurality of stays 9 to restrict a space between an upper punch supporting plate 4 and a lower punch supporting plate 2 when completing powder compression are provided between the upper punch supporting plate 4 and the lower punch supporting plate 2 through a die plate 1. In this case, one end of the stay 9 is fixed to the upper punch supporting plate or the lower punch supporting plate, and a position adjustment means 91 capable of changing the distance to restrict the upper punch supporting plate and the lower punch supporting plate is preferably provided on the stay or a part opposing the other end of the stay. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention particularly relates to a powder molding apparatus suitable for molding the height of a green compact with high accuracy.

  The press for powder molding includes a cam press, a crank press, a toggle press, a hydraulic press, and the like. Depending on the press mode, size, and shape of the molded body, various types of powder molding apparatuses are used. However, they are common in that the powder filled in the cavity is pressed by the relative movement of the die, the lower punch, and the upper punch. Among these powder forming apparatuses, for example, the structure of a whiz-dro apparatus is disclosed in Patent Document 1.

  FIG. 3 schematically shows an example of such a widow type apparatus. In this device structure, the base plate 2 is fixed to the bolster 10 of the press main body by bolts or the like. Below the base plate 2 is a lower ram (not shown), and the yoke plate 3 is connected to the lower ram. Above the base plate 2 is provided a die plate 1 in which a die forming a cavity is housed and fixed. The die plate 1 and the lower yoke plate 3 are connected by a plurality of guide rods 7 penetrating the base plate 2, and are simultaneously raised and lowered according to the driving of the lower ram. The lower punch 6 is fitted to a die hole provided in the die plate 1 while being fixedly supported by the lower punch presser 61 with respect to the base plate 2. Above the die plate 1, there is an upper punch plate 4, which can be raised and lowered by an upper ram (not shown). The upper punch plate 4 is provided with guide posts 8 that fit into the through holes of the die plate 1 so as to move up and down without inclination. The upper punch 5 is fixedly supported by the upper punch presser 51 with respect to the die plate 1.

  The green compact shown in FIG. 3 has a shape with no holes. However, in the aspect of forming a green compact with vertical holes, the upper and lower punches 5 and 6 are formed with vertical holes and are fitted in the vertical holes. A core rod is added. The core rod penetrates the base plate 2 and is fixed to the yoke plate 3 and is lifted and lowered together with the die plate 1 connected to the yoke plate 3 via the guide rod 7 (for example, Japanese Patent Laid-Open No. 2001-131606). Issue). In addition to the structure as shown in FIG. 3, the guide post 8 has a structure that is fixed to the base plate 2 as in Patent Document 1 or a structure that does not have the guide post 8.

In the above powder molding apparatus, when the die plate 1 is raised to a predetermined position, a cavity filled with powder is formed. The cavity is filled with powder by a powder feeder (not shown). Thereafter, the upper punch 5 enters the die hole, and the powder is compressed by the upper and lower punches 5 and 6 while the die plate 1 is lowered. The compression completion position is determined by the bottom dead center of the upper ram of the press, and the length of the green compact is determined. The green compact is released by raising the upper punch 5 and lowering the die plate 1.
Japanese Utility Model Publication No. 5-53794

  The green compact formed by using the conventional apparatus as described above usually has a height dimensional accuracy of about 0.1 to 0.15 mm, although it varies depending on the shape, cross-sectional area, compression pressure and the like of the green compact. Variations are possible. In terms of applications, there are some sintered products that do not interfere with the function even with this level of dimensional accuracy. For example, sintered products that are used in combination with other parts, those whose end faces slide, There are many sintered products that require a higher accuracy in terms of height, such as a plurality of laminated ones. In such a sintered product, post-processing such as cutting and grinding had to be added to the formed green compact. By the way, the height dimensional accuracy of the green compact cannot be obtained because the parallelism between the powder pressing surfaces of the upper punch and the lower punch deteriorates during the powder compression process even if a highly accurate die is used. It means that The cause is considered to be due to the accumulation of the inclination of the upper ram of the press machine, the deformation of the upper punch plate and the upper punch receiving plate (not shown), the inclination, the deflection, the inclination and deformation of the upper punch and the lower punch, and the like. In view of the above, the present invention has an object of improving the height dimension accuracy in particular, thereby enabling the post-processing to be omitted or simplified.

  In order to achieve the above object, the invention of claim 1 includes a die plate that can be moved up and down, a lower punch that is supported by a lower punch support plate and fits into a die hole of the die plate, and an upper punch support plate. An upper punch that can move up and down in a supported state, and compresses the powder filled in the cavity formed by the die hole and the lower punch by the relative movement of the die plate, the lower punch, and the upper punch. In the apparatus for forming a green compact, the upper punch is provided between the upper punch support plate and the lower punch support plate in a state of vertically passing through the die plate, and when the powder is compressed, the upper punch It is characterized by comprising a plurality of support columns for restricting the distance between the support plate and the lower punch support plate. Further, in this structure, as specified in claim 2, one end of the support post is fixed to the upper punch support plate or the lower punch support plate, and a portion facing one end of the support post or the other end of the support post ( (This portion indicates the lower punch support plate or the upper punch support plate side facing the other end of the support column), and the position where the distance between the upper punch support plate and the lower punch support plate can be changed An adjusting means is preferably provided.

  In the above invention apparatus, the interval between the upper punch support plate and the lower punch support plate is adjusted in parallel by a plurality of columns that restrain the interval between the upper punch support plate and the lower punch support plate at the time of completion of the powder compression. Therefore, the powder compression surfaces of the upper punch and the lower punch are also kept parallel, and as a result, a green compact with a uniform height can be formed.

  Hereinafter, an embodiment of the invention will be described with reference to FIG. 1 and FIG. This form is a withdrawal type powder molding apparatus similar to the conventional apparatus of FIG. 3, and the same reference numerals are given to the same constituent members as in the conventional apparatus. 1 and 2, the upper punch plate 4 corresponds to the upper punch support plate of the invention, and the base plate 2 corresponds to the lower punch support plate of the invention.

  This powder molding apparatus has the same skeleton structure as the conventional apparatus shown in FIG. That is, the base plate 2 is fixed to the bolster 10 on the press body side. Below the base plate 2 is a lower ram (not shown), and a yoke plate 3 is connected to the lower ram. Above the base plate 2, there is a die plate 1, and the die plate 1 and the lower yoke plate 3 are connected by a guide rod 7 that penetrates the through hole of the base plate 2, and can be moved up and down simultaneously according to the driving of the lower ram. ing. The lower punch 6 is fitted to a die hole provided in the die plate 1 while being fixedly supported by the lower punch presser 61 with respect to the base plate 2. Above the die plate 1, there is an upper punch plate 4, which can be raised and lowered by an upper ram (not shown). The upper punch plate 4 hangs down a guide post 8 fitted into the through hole of the die plate 1 so as to move up and down without inclination. The upper punch 5 is fixedly supported by the upper punch presser 51 with respect to the upper punch plate 4.

  The difference from the conventional apparatus is that it has a stopper rod (corresponding to the support column of the invention) 9 provided between the upper punch plate 4 and the base plate 2 in a state of penetrating the die plate 1 up and down. . A plurality of stopper rods 9 (3 or 4 in the embodiment) are provided around a die hole provided in the die plate 1. Of course, the position of the stopper rod 9 is set at a position that does not hinder the advancement / retraction of the powder feeder (not shown) and the removal of the powder compact (green compact). In this embodiment, the stopper rod 9 is fixed to the base plate 2, but may be fixed to the upper punch plate 4. The stopper rod 9 is made of a highly rigid alloy, more preferably a cemented carbide having a high Young's modulus. Further, structurally, it is preferable that the stopper rod 9 is supported by the through-hole 1a by using the through-hole 1a provided in the die plate 1 as a bearing hole, because the tilt of the die plate 1 is suppressed. Although it becomes an aspect, the structure which provided the clearance gap between the through-hole 1a and the stopper rod 9 may also be sufficient.

  The height of each stopper rod 9 is such that when the upper punch 5 is lowered and the compression is completed, the stopper rod 9 comes into contact with the upper punch plate 4 side and restrains the distance between the upper punch plate 4 and the base plate 2. Is set. In this case, a thin plate can be installed on the upper end surface of the stopper rod 9 so that the constraining distance can be variably adjusted, or an upper and lower adjustment plate provided on the upper punch plate facing the upper end surface of the stopper rod 9 is provided. It is preferable. In this embodiment, a position adjusting member 91 is provided on the lower surface of the upper punch plate 4. Although not shown, the position adjusting member 91 is provided with a male screw and is screwed into a female screw hole provided in the upper punch plate 4 so that the distance from the upper end surface of the stopper rod 9 can be adjusted. Further, the height of the position adjusting member 91 is increased, and the height of the stopper rod 9 fixed to the base plate 2 is the same as that of the upper surface of the die plate 1 when the die plate 1 is at the uppermost position (the cavity is deepest). With this structure, the powder feeder can advance and retreat the upper end surface of the stopper rod 9, which is suitable for a powder molding apparatus in which the mounting position of the stopper rod 9 is limited.

  In the powder molding, first, the die plate 1 and the upper punch plate 4 are raised to predetermined positions, and the powder is filled into the cavity formed by the die hole and the lower punch. While moving the upper punch 5 into the die hole and lowering the die plate 1, the amount of operation of the upper ram is adjusted so that the height of the molded body (green compact) becomes a predetermined dimension. Compress the powder. The green compact is released by raising the upper punch 5 and lowering the die plate 1, and one cycle is completed.

  By the way, at the time of manufacture, prior to powder molding as described above, the position adjusting member 91 is screwed into the upper punch plate 4 so that the upper end portion of the stopper rod 9 does not contact the position adjusting member 91 when compression is completed. Try to make. And as evaluation of the molded green compact, the height dimension of each part of the green compact corresponding to the right and left front and back of the die cavity is measured. The dimensional variation is usually about 0.1 to 0.15 mm. A portion having a short height means that the opposing surfaces of the upper punch 5 and the lower punch 6 are close to each other during compression.

  Next, in the ascending / descending cycle of the upper punch 5, the distance (a) from the position at which the lower surface of the upper punch 5 is located at the uppermost position to the position at the lowest position, and the upper punch plate 4 at which the lower surface of the upper punch 5 is located at the uppermost position. The position adjustment member 91 is adjusted and fixed so that the distance (b) between the upper end surface of each stopper rod 9 and the lower surface of the position adjustment member 91 facing each other is substantially equal. When this adjustment is performed, it is preferable to make the distance b slightly larger than the distance a, perform trial molding, and sequentially reduce the mutual distance. This is because both the upper punch plate 4 and the base plate 2 bend during compression, and the distance a increases, and as a result, the pressure applied to the stopper rod 9 may increase more than expected. When the powder is compressed as shown in FIG. 2 by the powder molding apparatus adjusted in this way, a plurality of stopper rods 9 of the same height standing from the base plate 2 at the time of maximum compression restrain the upper punch plate 4, Since the base plate 2 and the upper punch plate 4 are kept parallel, the upper and lower punches 5 and 6 are guided by the die holes to keep the compressed surface parallel, and the powder is compressed, so that there is little variation in height dimension. The body is obtained. From the comparative test using the apparatus of FIG. 1 and FIG. 3, the dimensional variation could be suppressed to 1/5 to 1/10 of the conventional structure by the inventive structure.

  Even after the position adjustment member 91 is adjusted as described above, the advance / retreat of the position adjustment member 91 corresponding to each stopper rod 9 is finely adjusted based on the setting where the distance a and the distance b are equal. Thus, it was also confirmed that the variation in height dimension in one obtained green compact could be reduced.

It is a longitudinal cross-sectional view which shows the apparatus of the invention form example in the state with which the powder was filled in the cavity. It is a longitudinal cross-sectional view which shows the apparatus of FIG. 1 in the state which compressed the powder from the powder filling state. It is a longitudinal cross-sectional view which shows an example of the conventional powder shaping | molding apparatus of a wids dral type.

Explanation of symbols

1: Die plate 2: Base plate 3: Yoke plate 4: Upper punch plate 5: Upper punch 6: Lower punch 7: Guide rod 8: Guide post 9: Stopper rod (support)
10: Bolster 91: Position adjustment member (position adjustment means)

Claims (2)

A die plate that can be moved up and down, a lower punch that is supported by a lower punch support plate and fits into a die hole of the die plate, and an upper punch that can be moved up and down while being supported by the upper punch support plate, In the apparatus for compressing the powder filled in the cavity formed by the die hole and the lower punch by the relative movement of the die plate, the lower punch and the upper punch, and molding the green compact,
Provided between the upper punch support plate and the lower punch support plate in a state of vertically passing through the die plate, and when the powder is compressed, the upper punch support plate and the lower punch support plate A powder molding apparatus comprising a plurality of support columns for restraining the interval. One end of the support column is fixed to the upper punch support plate or the lower punch support plate, and is disposed between the upper punch support plate and the lower punch support plate at a portion facing one end of the support column or the other end of the support column. The powder molding apparatus according to claim 1, further comprising position adjusting means capable of changing the distance of the powder.

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