US2043086A - Tablet compressing machine - Google Patents

Description

Jne 2, 1936. c. J. WESTIN ET Al. 2,043,086

TABLET coMPRsLN MACHINE Filed April 7, 1934` 4 Sheets-Sheet 1 I o A 27 l' f 6,4 /8 30 m l lo 0 'A' IU /2 I June 2, 1936. c. J. wEsTlN ET Ax. 2,043,086

TABLET COMPRESSING MACHINE Filed April '7, 1934 4 Sheets-Sheet 2 (s lr/Pmff June 2 1936- c. y.1. wEsnN ET Al. 2043,086

TABLET COMPRESS I NG MACHINE Filed April '7, 1934 4 Sheets-Sheet 3 g WVM/roes June 2, 1936. Q J, wEs-nN ET AL I 2,043,086

TABLET coMPREssING MACHINE Filed April 7,' 1934 4 Sheets-Sheet 4 S. t v @kwam/gy. k.

Patented June 2, 1936 PATENT oFFlcE TABLET COMPRESSING MACHINE Charles J. Westin and Albert Donaghy, Sr., Philadelphia, Pa., assignors to F. J. Stokes Machine Company, Philadelphia, Pa., a corporation oi' Pennsylvania Application April 7. 1934, Serial No. 719,508

6 Claims.

'I'he present invention relates to tablet-compressing machines which may be of the rotary type, and pertains particularly to new and useful improvements in the principles of construction which result in economy of manufacture,

greater convenience and `eiiiciency .of operation, and which materially increase the production rate of the machine.

Features of .our invention are new and improved means for holding and adjusting the powder feed frame or grid; new and improved means for adjusting the mold-fill or weight-adjuster; new and improved means and methods for the prevention of dirt around the machine and for dust removal, or for both; and other features relating to details of economies of construction and operation which will denitely appear from the description to follow.

In the drawings:

Fig. 1 is av perspective lview of our device with housing 28 omitted; Y

Fig.` 2 is a diagrammatic and schematic development showing parts of the machine and the way in which they operate, with parts shown in cross-section;

Fig. 3 is -a plan view of the grid, indicating the adjacent parts of the machine;

Fig. 4 is a side view of the grid and the moldiill or weight-adjuster cam, with parts in vertical cross-section; and

Fig. 5 is a view in side elevation of the upper part of our machine, with parts in vertical crosssection.

In that embodiment of our invention chosen for illustration in the drawings, there is shown a machine of this general type consisting of a frame I I provided with a base I2, a stationary table I3 with a central spindle I4 (Fig. 5) on which a rotating mold tableor head is mounted. The head I5 is rotated in the direction in dicated in Figs. 1 and 2 by the arrow A, as, for example, by a worm-gear I6 (Fig. 5) attached to head I5 and co-operating with a worm (not shown) mounted -on shaft I8, which is driven from any convenient source of power. As is best seen in Fig. 5, the head I5 is of such construction that a number of 'rings or annular disks are superimposed with smaller vrings or necks in between, forming a structure of several stories and of diameters to suit the co-acting mechanism.

A pluralityof apertures are spaced around the head and cut y clear through the several stories,-

to form bearings and seats for` the plurality of upper punches 20, .lowerpunches 2l and molds 22. The punches are caused to co-operate with grid 21 is mounted on housing 28. Grid 21 is yof the center line of 'molds 22.y At its oitake end, yor rear end in the direction of rotation of ta- (Cl. 10V-17) the mold 22 through cam tracks (best seen in Fig. 2); 23 for the upper, 24 for the lower; or through the upper compressing roll 25 and lower roll 26.

Fig. 2 shows step-by-step in sequence the functions of each set of punches for a complete revolution of 360 of the head I5.v The degrees marked along the top are arbitrarily chosen and merely serve the purpose of showing the synchronized action of the parts. At the 0 line, the lower punch 2| starts down, opening the mold cell and the powder iiows in, completing the lilling at about where the punch again rises, lifting some of the powder out of the mold, the excess being scraped'off at 140. -From this point the lower punch may travel straight or be lowered as the case may be, until it strikes the roller 2B at the same time, or approximately so, that the upper punch 20 strikes the roller 25 and the powder is compressed into a tablet at 270. At the 330 line, the tablet has been lifted out of the mold and rides of! the mold table 30 onto the discharge chute 31 (Fig. 3) at about 350.

Referring to Figs. 3 and 5, a feed frame or 25 stationary in respect to the rotating head I5 and the mold-table 30 thereon but extends in over the mold-table, so that the mold table forms the bottom of the grid and, as the head rotates, new molds are successively presented under the grid forA iilling. Grid 21 consists of a labyrinthian structure formed by walls |21, having openings |28 therein alternately spaced on opposite sides ble I5, grid 21 carriesa scraper I 29, which projects through al slot in the outer wall of grid v 21, and which is pressed by a spring |30 into contact with the surface of mold table 30.

Grid 21 receives the material from hopper 20' 40 and, because of its labyrinth-like'construction (Fig. 3) and the co-operating effects between the labyrinth and the rotation of the mold-table 30 underneath, the material moves back-and-forth over the molds v22, and, as the punch 2l recedes 45 down from the ejecting position opening the mold-cell to its full capacity, the material iiows into this cell land iills it. The grid always maintains a surplus amount of material (indicated at B in Fig. 4) above the mold and the action of 50 punch 2I is such that the mold-cell will receive more material than is needed for the tablet to be compressed but the surplus in the grid, together with the excess powder placed in the grid, is scraped 01T by scraper |29 as the punch 2| 55 have the supporting means so arranged that the grid 21 may quickly be removed from the machine or detached from the support 38 on housing 28 without disturbing the adjustment. This can readily be done with the arrangement of.

parts as shown. Heretofore, using a plain stud or screw rigidly attached to lug 36 on housing 28, it would cause a very undesirable mess and alot of wasted material when opening or removing housing 28 in order to get in to gear I6 and punches 2|, which frequently is a necessary op-l eration. With the novel arrangement of the double threaded cap or thimble 35 supporting the bolt 82, which is clamped to thelug 83 of grid 21, it is possible to adjust and set the grid at the desired level and, when necessary, to unfasten it from 88 and open housing 28 withoutdisturbing the powder on mold-table 80. The bolt 82 is therefore made of such a length that it does net reach down to the support 36 but has a sufficiently free, but threaded, space 32a above cap 88, so that the cap 85 may be screwed-up on 82 when unscrewing 88 from 88 to clear the top of 28. This is accomplished by having the two threads, that is, the thread 82a, on bolt 82 and 88a on cap 38, so arranged that they will cooperate properly. Both threads must be cut the same hand, either left-hand or right-hand, and may be of the same pitch, for example, I3 threads per inch, but we prefer to make 82a of a finer pitch than 88a; for example, I8 threads per inch. while 88a is cut with I'threads per inch. This 4 is so that, in unscrewing cap 85, it will slightly lift the grid 21 away from the mold-table 30, instead of pulling the grid 21 down and clamping it against the mold-table 80, thus jamming the cap 85 and making it impossible to unscrew it, which vwould be the case if the relative arrangements of the threads were reversed. The grid 21 is adjusted and set by nrst tightening cap 85 and, with lock-nut 34 loose,.the support 82 can be adjusted to hold the grid at the desired level. Then clamp the lock-nut 34 tightly and, when the cap 85 is unscrewed to release the grid 21, itwill return to exactly the same original position when again tightened in 38.

Referring to Fig. 4, our invention embodies some new kand. useful improvements in the construction and operation of the weight-adjusting mechanism or cam. The cam 48 has a long and gentle slope, providing an easy and gradual rise for punch 2| as it is lifted'to form the proper cell depth, regardless of the height to which the punch 2| may be lifted within the range of the machine. Cam 48 has a face 48a in the shape of a ring sector, as seen in plan view, Fig. 3,'on a radius conforming to the radius ofthe punch centers, as seen in plan view. and cam. is adjustable in a slot or recess 44 of the stationary table I8 and support 48. The cam 48 is provided ing or lowering cam 48 and is held in the desiredv position by screw 41 because of the collar 48, on the one side, and hand-wheel 5| on the other side of the support 48. A spring 52 may be usedV as a lock to prevent the screw from turning accidentally. 5 Heretofore, instead of the long ring sector 40a. which provides a gentle slope covering the complete range of adjustment for the weight-adjustment, a plug or disk was used, which necessarily was limited in diameter and, therefore, 10 only had a short and abrupt cam surface, usually requiringa series of auxiliary cams or wedges in front and back in order to cover the complete range of adjustment. In addition to the above inconvenience of having to change wedges, it l5 was necessary, when operatiim at maximum production speeds, to provide a hold-down for the punch to prevent the punch from jumping oif the cam as it reachedthe apex, which jumping would cause uneven weight of tablets and necessitate 20 operating at reduced speeds. By the use of our invention, all the above diillculties are eliminated.

We have also found it desirable to'provide a bridge 43 closely following the inside outline of 25 cam 40 and fastened to the top of table I8, to prevent the punch from dropping down below the top of table I3 in case the slot 44 should happen to be wider than the diameter of the punch heads. It will be noticed that the cam is 30 comparatively narrow, so that the punch head extends about one-third over the edge of the cam. Slot 44 may, of course, be machined to a nice flt with cam 48, in which case the table would Y support the punch, but for the sake of 35 economy in manufacture slot 44 is cored at the time of casting the table and can, therefore, not be held to such close dimensions that it will furnish lsuflicient side support for the punch when the low points of cam 48 areI below the table top. 40

The bridge 43 nicely serves the purpose of cooperating with cam 48 in forming a continuous support for the punch.

Although materials compressed into tablets are supposed to be granular, they usually contain a 45 certain percentage of fines as well as dust and, while the grid 21 is constructed so as to confine as far as possible all the material and prevent any of it from escaping,l we find that in machines of this type, where large quantities constantly 50 are in motion, considerable dust is produced and will accumulate around the working parts of the machine. 'I'his dust mixes with 'the lubricant used on the moving parts, creating avery dirty and undesirable condition. With some materials, 55 the dust has a tendency to absorb the oil in the lubricant, thereby quickly drying the surfaces which results in excessive friction, causing the punches to bind in their bearings, the gearing to wear out, and, in general, is a source of serious ou trouble and expense. Our invention overcomes 4these difficulties by the novel arrangement of making head I5 and housing 28 co-operate to the extent of 4preventing dust from accumulating on mold-table 88 and-punch bearings 8l, and 65 keeping dust out of the gearing and the other parts within the housing. It will be noticed that v the head I5 is constructed so that mold-table 38 isof a larger diameter thaxnpunch bearings 8| and, therefore, extends out over the punch bear- 70 ings, and any granulated material dropping oif table 30 will fall on the incline 82 of housing 28 and slide .down into the gutter away from the rotating head l5. Furthermore, bearings 8| are provided with a shelf which extends out over the edge 83 of housing 28. Dust and dirt scraped oi this shelf 8| will, therefore, drop onto the incline 82 and also slide down the gutter, where all of it can be collected and conveniently removed wit-hout interfering with the operation of the machine. v

Most of the dust is created at the ycompression point, where a. puff of dust is carried up out of the mold 22, as well as down through the mold, by the air expelled in the process of compressing the tablet. These puis of dust would iloat around and settle all over the machine, as well as all over the room, unless removed at the source. By providing an effective suction system mounted on the frame of the machine or on the housing 28, as shown, we have eliminated this source of trouble. The suction system may consist of two nozzles. and 85 connected to a. suction fan or dust-collecting system, or the two nozzles may be combined into a double nozzle, asshovm in Fig. 5, and piped to thev exhausting arrangement (not shown). When expensive material is being compressed, a considerable saving is effected by collecting the dust and mixing it with virgin materiai for re-use.

By the suitable arrangement of protruding shelves on the head I5, in combination with a properly constructed housing 28 and effectively placed suction nozzles, the machine is .kept clean, avoiding the losses otherwise caused by frequent shut-downs for cleaning and repairs.

We do not intend to be limited save as the,

scope of the prior patents and of the attached claims may require.

We claim:

l. In a tablet machine, a stationary table, first means for conveying a plurality of molds and a plurality of punches for co-operation with said molds, second means for compressing material between pairs of said punches, a grid mounted adjacent said molds so that said molds are movable relative thereto, a hopper mounted to feed material to said grid, bolts forming supports for said grid, caps having screw-threaded engagement with said bolts and having screw-threaded engagement' with said table, a cam projecting through an opening in said table for co-operation' with the llower ones of said plurality of punches, said cam-having a face in the shape in plan of a' ring sector on a radius conforming to the radius of the punch centers, and located so as to raise the lower ones of -said plurality of punches and to adjust the amount of material received by said molds, and means mounted on said table adjacent said second means at the point of compression of said punches ior-removing dust from around said molds and said punches.

2. In a tablet machine, a stationary table.-a mold' table mounted for movement on said stationary table and carrying therein a plurality of molds and a plurality of punches for co-operation with said molds, a grid mounted on said stationary table above that portion of said mold table carrying said plurality of molds, bolts forming supports for said grid, and caps having screwthreaded engagement with said bolts and having screw-threaded engagement withsaid stationary table, whereby said grid may be disengaged from said stationary table by unscrewing said caps.

3. In a tablet machine, a stationary table, a mold table mounted for movement on said stationary table and having a plurality of molds and a plurality of punches for co-operation with said molds therein, a housing mounted on said stationary table and encircling and underlying portions of said mold table, a. grid mounted above that portion of said mold table having the molds,

bolts forming supports for said grid, and caps having screw-threaded engagement with said bolts and having screw-threaded engagement with said housing so that said grid may be rejacent said mold table, caps having screw-thread- I ed engagement with said bolts and forming supports therefor, and a housing having screwthreaded engagement with said caps, the screwthreads between said caps and said bolts being of no greater pitch than the screw-threads between said caps and said housing, said housing forming -a support for said caps and for said bolts and said grid thereon.

5. In a tablet machine, a stationary table. a mold table having a plurality of molds and a plurality of upper and lower punches therein, a cam extending through a perforation-,fin said stationary table and having a face in the shape in plan of a ring sector on a radius conforming to the'radius of the centers oi said punches, a

support for said cam, andl screw-threaded means interposed between said cam and said support for adjusting the height of said cam.

6. In a tablet machine, a stationary table, al

mold table having a plurality of molds and a 13.

plurality of upper and lower punches therein, a cam projecting through a perforation in said stationary table for co-'operating with said lower punches, said cam having a face thereon which conforms in plan to the path of movement of

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