JPH0246319B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel powder compression device that produces compression molded products with no difference in compression pressure when compressing powder using a powder compression device in the fields of pharmaceuticals, foods, agricultural chemicals, fertilizers, etc. . One of the major drawbacks of the powder compaction equipment commonly used in the past is that it uses a pressing force of 1 to 10 tons to compress lactose, ceramic powder, antibiotics, antioxidants, etc. at the roller compression site. % or less, the compression pressure of about 300 kg/cm or more is not uniformly applied across the width of the roller. Because the compression pressure is not uniformly applied, it has been the case that only compression molded products with different molding hardnesses, densities, etc. of the powder can be produced. Therefore, when the degree of compaction affects product properties, for example in the compression molding of pharmaceuticals, the stability, disintegration (solubility), strength, etc. of the compression-molded drug differ depending on the compressed part, so the product quality may be affected. At present, this is causing major problems such as not being able to maintain a constant temperature and resulting in a decrease in yield. Generally, the purpose of compressing and solidifying powder is to obtain a lump of powder and to create a flake-like powder solidified product. (Flake-like solidified powder can be crushed with a crusher to obtain granules.) In this case, when handling powder with a small friction coefficient between the powder and the surface of the compression roller, This makes it easier for the powder to slip, and more so-called uncompressed powder passes between the compression rollers without being compressed and solidified. In particular, seal plates are provided at both ends of the compression roller to prevent powder from leaking, which acts as a brake on the movement of powder between the compression rollers. The amount of uncompacted powder increases. When there is a large amount of uncompressed powder, it is necessary to separate it from the compressed and solidified material and re-compress and solidify it, which reduces production efficiency and may cause quality deterioration due to double compression. In order to reduce the amount of uncompressed powder and to make the compression distribution uniform across the width of the roller,
In order to better trap the powder in the compression roller,
Previously, the roller surface was corrugated, narrow grooves were formed on the roller surface, and a forming roller with a concave surface was combined with a forming roller with a concave surface. With rollers, there is a problem with the interlocking between the rollers, making it difficult to produce flakes with a uniform thickness.Additionally, it is easy to create thin grooves on the roller surface if the roller surface is smooth, but the shape of the roller surface is complicated. Compression molding using a combination of concave rollers and convex rollers can compress and solidify most powders with uniform compression force distribution, but the friction between the powder and the roller surface When handling a small portion of powder, there was a particularly large amount of uncompressed powder near the side seal plate placed at the end of the roller, and in some cases, the powder was not sufficiently compressed and solidified even in the center of the roller. The present inventors used a powder compression device in which a narrow groove was formed in the center of a combination of concave rollers and convex rollers in order to be able to handle powders with as wide a variety of physical properties as possible. For some kinds of powders with good fluidity, the uncompacted powder near both ends of the roller reached about 30% of the powder throughput, making it unsuitable for practical use. In addition, in such a powder compression device, the shape of the roller periphery is relatively difficult, so processing to improve the frictional characteristics of the roller surface is difficult, and therefore it is difficult to improve compaction and solidification properties. . The inventors of the present invention have conducted various studies on a practical uniform compression device that can overcome these various difficulties, and as a result, they have devised a method to sandwich the powder between a pair of compression rollers consisting of a concave roller and a convex roller. , in a powder compression device that rotates a compression roller and compresses and solidifies the powder by passing the powder between the compression rollers, the both end wall portions of the groove of the concave compression roller and the both end wall portions of the convex portion of the convex compression roller are connected to each other. In addition to having an inclined surface that fits, the angle of inclination is 20 to 85 degrees, and
The depth of the groove and the height of the convex part are 0.5 to 10 mm,
and at least 1/20 of the width of the compression roller on the surface of the compression roller inwardly from both ends of the compression roller.
It was discovered that the powder can be compressed uniformly when a hardened uneven surface with an average depth of 50 μm or more is provided on the above portion by powder injection molding, and based on this, the present invention was completed. That is, the present inventors
We found that the frictional characteristics between the powder and the solid surface change significantly when the solid surface is roughened with an average depth of 50 μm or more.As a result of various studies on the workability of compression rollers, we found that We have discovered that a good friction coefficient and wear resistance can be obtained by applying a Blasting Peening process to create unevenness or a powder spraying process (Thermo Spray process). Furthermore, both end walls of the concave compression roller and the convex compression roller that fit into each other are sloped at an angle of 20 to 85 degrees, and the depth of the groove and the height of the convex portion are adjusted.
It has been found that by setting the thickness to 0.5 to 10 mm, both end walls do not act as a brake on the movement of powder, and the generation of uncompacted powder near both ends of the roller can be almost eliminated. Therefore, the present invention provides a powder compression device for compressing and solidifying powder by rotating a compression roller so as to sandwich the powder between a pair of compression rollers. It makes it easier to pinch, compresses and solidifies the powder uniformly over the entire surface of the compression roller, and greatly improves its so-called compression and solidification properties.At the same time, it increases the abrasion resistance of the compression roller and improves its durability. The present invention provides a new powder compaction device. To explain the present invention with reference to the drawings, FIG. 1 shows a schematic side view of a powder compression device using the rollers of the present invention, in which 1 is a fixed roller, 2 is a movable roller, 3 is a supply hopper, and 4 is a screw. , 5 is a powder, 6 is a motor, 7 is a molded product, and the arrow indicates the rotation direction. FIG. 2 shows a cross-sectional view in a plane including the tangents of both rollers 1 and 2 and the center of rotation of both rollers. The groove on one of the rollers, which is provided at the end of the part where both rollers contact each other as shown in FIG. ~8mm. Note that the angles of the grooves and the protrusions have an appropriate radius, and the slopes of the grooves and the protrusions may not necessarily be straight lines, but the inclination angle in this case is an average value. The average thickness of the ditch bank should be at least as thick as it can withstand in terms of strength, and is usually 5 to 10 mm.
The above is used. The width of the bottom surface of the groove is usually up to about twice the diameter of the roller, but there is no particular restriction as long as a suitable molded product can be obtained. Also,
The surface of the roller at the embankment of the groove does not necessarily have to be parallel to the bottom surface, and a plurality of shallow grooves such as knurling grooves may be provided on the bottom surface of the roller. A pair of compression rollers 1 and 2 having the above shape
In the powder compression device, the screw 4 is rotated by a motor 6 so as to sandwich the powder supplied from the hopper 3 between the rollers 1 and 2, and the powder is compressed and solidified by passing the powder between the rollers 1 and 2. The average depth obtained by applying powder injection molding processing such as satin finishing or powder spraying processing to the surface of 2, inwardly from both ends of the roller, and at least 1/20 or more of the roller width.
An uneven surface 8 of 50 μm or more is provided. The above roller 1,
No. 2 is made of iron or an iron alloy, and the satin finish, which is a powder injection molding process applied to the surface of the iron, produces a relatively glossy finish, as is well known, by blowing glass beads onto the surface of a roller used as an abrasive material for blasting. A satin finish is generated and a hardened uneven surface 8 having an average depth of 50 μm or more can be obtained. In powder spraying, which is an alternative to satin finish, the surface of the roller is heated, and then iron or iron alloy powder or particles are sprayed by thermospray to weld a large number of them onto the surface, which hardens the surface. An uneven surface 8 having an average depth of 50 μm or more can be obtained. The powder injection molding process applied to the surface of the roller may be performed on the entire surface of the roller as shown in FIGS.
It may also be applied to a portion of the roller as shown in (b) and (d). When performing powder injection molding on a portion of the roller surface, the effect will be small if the powder injection molding is performed only on a small area of at least 1/20 or less of the width of the compression roller on both sides of the roller. That is, the inventor used an uneven roller with a roller diameter of 100φ as shown in FIG. When the uncompressed rate of the powder that is compressed and solidified by incorporating it into a powder compression device that has been finished with a satin finish only on the distance part, it is found that the fifth
As shown in the figure, it was found that unless the ratio of the machining distance from the roller end to the total width of the roller was 1/20 or more, the uncompressed ratio of the powder to be formed would exceed 20%, making it impossible to put it into practical use. did. In other words, in this type of powder compression equipment, the powder is usually not sandwiched between the rollers near the side seals of the compression rollers, resulting in a large amount of uncompressed powder. Powder injection processing was applied. As the molding rollers used, a pair of rollers each having a concave surface and a convex surface were used, and compression and solidification were performed for each roller by varying the distance from the end surface of the roller to the portion to be processed. As shown in Figure 5, by performing powder injection processing on a portion of 1/20 or more from the end face of the roller, it was possible to significantly reduce the amount of uncompressed powder. Incidentally, when the surface of the compression roller is subjected to powder injection processing, the coefficient of friction can be increased as shown in Table 1, and at the same time, the wear resistance can be decreased, and the life of the roller can be extended.

[Table] Furthermore, when performing a satin finish on the surface of a roller, a flat roller with a roller diameter of 100φ is used to spray glass beads onto the surface of the roller. When the powder was compressed and solidified using a processed roller using beads, beads with a larger particle size range than glass bead number FGB-150 (particle size approximately 125 to 105μ) were used, as shown in Figure 4. In some cases, we were able to reduce the uncompressed ratio. Not only is the processing cost of matte finish lower than that of groove processing, it can be easily processed even with a forming roller of a complicated shape, and it is also possible to process only the necessary parts. In particular, in a powder compression device that uses two compression rollers with concave and convex roller surfaces, the part near the roller end has a complicated shape and is difficult to groove. Machining of such parts is also easy. As described in detail in the above embodiment, in the powder compression apparatus, the compression rollers are rotated so as to sandwich the powder between the pair of compression rollers, and the powder is compressed and solidified by passing the powder between the compression rollers. With a simple structure, an uneven surface with an average depth of 50 μm or more, which is hardened by powder injection molding, is provided on the surface of the compression roller inwardly from both ends, at least in a portion of at least 1/20 of the width of the compression roller. , the friction coefficient of the roller is increased to improve compaction and solidification of powder, while at the same time improving its abrasion resistance so that it can withstand long-term use. Its practical value is great because the body development is reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a powder compaction device using the rollers of the present invention, FIG. 2 is a sectional view of a pair of rollers used in the device of FIG. 1, and FIGS. Fig. 4 is a diagram showing the relationship between the glass bead number and the uncompressed ratio of the granules when the roller is subjected to satin finishing.
The figure is a diagram showing the relationship between the processing distance from the end of the roller and the uncompressed rate of the granules when the roller is subjected to a satin finish. 1, 2...roller, 8...part with uneven pattern.

Claims (1)

[Scope of Claims] 1. A powder compression device that rotates a compression roller so as to sandwich the powder between the pair of compression rollers, and compresses and solidifies the powder by passing the powder between the compression rollers, comprising: One of the rollers is formed with a groove on its outer circumferential surface that has both ends protruding and a concave central portion to form a concave roller, while the other roller has a convex portion that fits in the groove on its outer circumferential surface. Both end walls of the groove of the concave roller and both side walls of the convex part of the convex roller are sloped surfaces of 20 to 85 degrees, and the groove depth and the height of the convex part are 0.5.
~10mm, and the surfaces of the concave and convex compression rollers are subjected to powder injection molding on a portion of at least 1/20 of the width of the compression roller inside from both ends of each compression roller to harden and harden the average. A powder compression device characterized by having an uneven surface with a depth of 50 μm or more.