|Publication number||US3384035 A|
|Publication date||May 21, 1968|
|Filing date||Jun 2, 1965|
|Priority date||Jun 2, 1965|
|Also published as||DE1577251A1|
|Publication number||US 3384035 A, US 3384035A, US-A-3384035, US3384035 A, US3384035A|
|Inventors||Alexander Jr John M, Hamilton William H, Harry Gabriel|
|Original Assignee||Pennsalt Chemicals Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (6), Classifications (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
May 21, 1968 GABRIEL ET AL. 3,384,035
INDUSTRIAL PROCESS AND APPARATUS Filed June 2, 1965 INVENTORS. HARRY GABRIEL JOHN M. ALEXANDER,JR.
B M AM H. AMILTON a! II M ATTORNEY United States Patent 3,384,035 INDUSTRIAL PROCESS AND APPARATUS Harry Gabriel, Churchville, and John M. Alexander, Jr.,
and William H. Hamilton, Philadelphia, Pa., assignors to Pennsalt Chemicals Corporation, Philadelphia, Pa.,
a corporation of Pennsylvania Filed June 2, 1965, Ser. No. 460,779 Claims. (Cl. 107-17) ABSTRACT OF THE DISCLOSURE In a rotary tabletting machine the means for adjusting the vertical position of the pull-down cam while the machine is in operation correspondingly adjusts the level of the lower tablet punch in its lowermost position during the die-filling operation.
This invention relates to means for moving the punches of rotary tabletting machines. More specifically the invention relates to means for controlling the lowering of the lower punches of such machines during the die-filling operation.
In the rotary tabletting machines of the prior art a rotary table has presented dies spaced uniformly about it and has carried over the dies and under the dies a series of aligned cooperating vertically reciprocable punches. Material has been deposited onto the table, the lower punches have been lowered successively to a lower extreme or initial fill position and material has been scraped into the associated dies. The lower punches have been then raised to adjust accurately the volume and hence weight of the material in each die, and overfill material has been scraped off the top of the die. The upper and lower punches have been brought together into the die under great pressure by appropriate cams or rolls. Subsequently the lower punch has been raised to eject the finished tablet out of-the die and the finished tablet has been moved off the table.
The drawing of the lower punch down to a low initial fill position before raising it to the weight adjusting level has assured that the die is totally filled when the lower punch is raised to the weight adjuster position.
In prior art machines the weight adjuster cam has been movable up or down while the machine is running to adjust the weight of material in the tablet products, If, for instance, the bulk density of one batch of material to be tabletted is relatively low, the cam may be set lower to accept more volume of material than in a second batch which is of higher bulk density. In this fashion the weight of the tablets in the two batches will be uniform.
The adjustment of the weight adjuster cam to a high level has brought the problem, especially in large diameter tablets, of flooding the tabletting machine with an excess of overfill scrapings. This rejected material has accumulated in excess on the die table and has spilt over the feed frame back into the die cavities causing varying tablet weight. Excess material has also worked out into the dies causing varying tablet weights and has been thrown off of the table altogether to result in sloppy operation and much wastage. Free loose powder has in this manner worked its way into the finished tablet receptacle. A separate problem has arisen in instances in which the overfill has been high: the scrape-off operation has sometimes left a concavity in the top of the fill in the die causing an underweight tablet.
To avoid the wide difference between the extreme low point or initial fill position and the high settings of the weight adjuster cam and its consequent problems, filler plates and lesser drop pull down cams have been selectively installed in the machine to raise the low point. The selective replacement of these cams and filler plates, however, has been unsatisfactory since it has required a stoppage of the machine and a partial disassembly. It has also required the expense and storage of multiple extra sets of filler plates and cams.
In accordance with the present invention there is provided means to adjust the position of the pull-down cam while the tabletting machine is in operation. The distance between the initial fill position and the weight adjuster cam can thus be kept constant as the position of the weight adjusting cam is changed.
A feature of the invention involves means to assure that as the pull-down cam is lowered its inclined portion remains in constant relative position with respect to the horizontal. This results in even and uniform contact of the cam and the punches and avoids binding and excessive wear of the punches against the cam.
Other features of the invention will be apparent from the following specification including the drawings wherem:
FIGURE 1 represents a fragmentary top view of an apparatus embodying the invention and taken above the pull-down cam;
FIGURE 2 is a fragmentary sectional view on line 22 of FIGURE 1 showing the pull-down cam and the weight adjuster cam with the upper punches shown in phantom; and
FIGURE 3 is an enlarged sectional view taken on line 3-3 of FIGURE 2.
Briefly, in a rotary tabletting machine, the invention comprises means for adjusting the vertical position of the pull-down cam while the machine is in operation to correspondingly affect the level of the lowermost position of the lower tablet punch during the die-filling operation.
Referring more specifically to the drawings, an apparatus embodying the invention is shown in FIGURE 2. It comprises a rotary table 12 which mounts a plurality of dies 14. Lower punches 16 are mounted in the table in openings under the dies 14 while upper punches 18 (shown in phantom) are mounted in another portion of the rotary table (not shown) and are adapted to cooperate with the lower punches 16 to compress tablet material in the dies 14. Each of the punches is formed with a head 16a by which the vertical movement of the punch is adapted to be restrictively controlled.
Mounted on frameztl under the table 12 is a stationary pull-down carnsection 22. This section comprises a pair of inwardly directed spaced tracks 24 which engage successively the top bevel portions of the heads 16a of the lower punches. As shown in FIGURE 1 the stationary section of the pull-down cam is formed with a longitudinal recess 26.
Positioned above the frame 20 adjacent the cam section 22 is movable pull-down cam section 28. This section is provided with a floor 30 and, like the section 22,
is provided with inwardly directed spaced tracks 32 to engage each punch head 16a. The movable section 2.8 of the cam is provided with a tongue element 34 which extends into the recess 26 to make a continuous limit for the lowermost position of the head 16a, should the punch fall under gravity.
To the left of the movable section 34 of the pull-down cam as shown in FIGURE 2 is the weight adjuster cam 36. As shown in FIGURE 1 the weight adjuster cam 36 is adapted to engage the head 16a as the punch moves in the rotation of the table 12.
It will be understood that as the table 12 rotates in the direction of the arrow (FIG. 2) the lower punches first engage the pull-down cam 22, 28 and are drawn down to an extreme low point. They subsequently are engaged by the 3 weight adjuster cam 36 and are raised to the accurate weight fill level as indicated by the punch 16'. Overfill material rejected above the die 14 is leveled off by a fixed scraper or doctor (not shown). The lower punch then may fall to the dwell cam 37 before the pressure means brings the punches together in the die.
The weight adjuster cam 36 is supported on a shaft 38. The lower end of the shaft is reduced and threaded at 40 and receives a bevel gear 42, the central opening of which is correspondingly threaded. The shaft 38 is vertically movable, but is held against rotation by being secured to the cam 36 which itself is confined by set screws 39 in the cam 37. Journaled \in the gear box frame 44 is a crank shaft 46 which fixedly mounts a second bevel gear 48. With this arrangement the turning of the crank 50 will adjust the vertical position of the weight adjuster cam 36.
The movable section 28 of the pull-down cam is supported on 'a pair of studs 52 and 54 which extend through openings in the frame 20. Mounted on the underside of the frame is the drive sleeve housing 56 which is formed with openings to receive respectively the internally threaded sleeves 58 and 60'. The sleeves carry outward flanges about their upper ends which are supportingly engaged by the housing 56. The sleeves are free to rotate in the housing.
The sleeves 58 and 60 extend downward and terminate in reduced shafts 62 and 64 respectively. These shafts are appropriately journaled in bushings in the pull-down cam gear box 66 and are coupled for rotation by sprockets 68 and 70 over which is trained a chain 72. By this means sleeves 58 and 56 are made to rotate in unison and since the threads in the sleeves are matching, the studs 52 and 54 rise and fall in unison assuring that the movable section 28 of the pull-down cam remains in constant position with respect to the horizontal.
To drive the shafts 62 and 64 a bevel gear is fixedly mounted on the shaft 62. Engaging this bevel gear 74 is a second bevel gear 76 which is mounted on a drive shaft 78 journaled in the gear box frame 66. Rotatably linking the crank shaft 46 and drive shaft 78 are a pair of sprockets 80 and 82 over which is trained the chain 84.
By means of the arrangement shown when the crank 50 is turned, the weight adjuster cam and the movable section 28 is raised or lowered. The threads on the stud shafts, the ratios of the sets of bevel gears, and the relative sizes of the chain sprockets are such that the movement of the weight adjuster cam will be met by a similar movement of the movable section 28.
For independent movement of the weight adjuster cam without corresponding movement of the movable section 28 as is desired in setting the overfill distance, sprocket 82 may be disengaged from the shaft 78 and the shaft turned. When the section 28 has reached the desired relationship to cam 36, sprocket 82 is -re-engaged. A variation of the structure involves two separate hand cranks, one for shaft 46 and one for shaft 78, eliminating the sprockets 80 and 82 and the chain 84 and providing totally independent control for the two cams. Since for most operations the overfill may remain constant, independent control is usually neither desirable or necessary.
As shown in FIGURE 2 a fixed section 22 of the pulldown cam will assuredly lower the lower punch 16 so that the head 16a is at a level just below the point A. The movable section 28 of the pull-down cam will assure that the head 16a is further lowered to a point at which the head 16a is immediately below the movable point B. Point B can be raised or lowered. The floor of the movable section 28 limits downward movement of the head 16a should the punch fall down and not need to be drawn down by the tracks 32. While there is considerable distance between the tracks 32 and the floor 30 adjacent the stationary section 22 of the pull-down cam, at the point B the distance closes down so that control over the position of the head 16a is exact to afford precise posi- .4 tion'ing of the punch at its lowermost point whether the punch 16 falls or is pulled downwardly.
As a result of the structure disclosed and other embodiments of the invention, it is possible to control accurately and adjust the lowermost position of the lower punch prior to the weight adjuster station. This affords means for controlling the amount of material loose on the die table with consequent indicated advantages. A special advantage of the embodiment shown is the constant angle maintained by the cam incline as the section 28 is raised or lowered. This avoids excessive wear and binding of the punches and cam.
The invention may be practiced with any kind of means including a cam for limiting the downward travel of the lower punches, whether they are the so-called pull-down cams or those wherein cams function merely to limit the downward travel of the lower punches which normally or occasionally fall under gravity.
The present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof and, accordingly, reference should be made to the appended claims rather than the foregoing specification as indicating the scope of the invention.
1. A tabletting machine comprising a stationary frame, arotary table supported on the frame, dies and cooperating upper and lower punches mounted on the table, means including a first cam for limiting the downward travel of the lower punches and a weight adjuster second cam disposed under the table and adapted respectively to engage the lower punches successively to lower them to a low initial fill position and then raise them to a position for accurate weighted fill, and means on the frame adjustably supporting the two cams whereby the cams may be adjusted in vertical disposition either independently or in unison while the table is rotating for controlling the extent of overfill during the initial filling of the dies as well as for accurately controlling the weight of the fill.
2. A tabletting machine as described in claim 1 wherein the means for adjustably supporting the first cam comprises a pair of spaced supports and means adapted to move the supports in unison to maintain the first cam in constant relation to the horizontal.
3. A tabletting machine as described in claim 2 wherein the means to move the supports in unison comprise rotatable threaded elements rotatably linked together.
4. A tabletting machine as described in claim 1 wherein the first cam has inwardly directed tracks and the lower end of the lower punches have enlarged heads and are adapted to be engaged on the heads by the said tracks.
5. A tabletting machine as described in claim 4 wherein the first cam is formed with a floor spaced below and intermediate the tracks, said floor being adapted to engage the lower surface of the punch, and the vertical distance between the tracks and the floor decreases as the weight adjuster cam is approached.
6. In a tabletting machine comprising a frame, a horizontally disposed rotary table mounted on the frame and carrying a plurality of dies, a plurality of upper and lower punches mounted in the table above and below the dies respectively for movement toward and away from the dies, means including a first cam for limiting the downward travel of the lower punches being disposed below the table and adapted to engage a lower portion of the lower punches successively as the table rotates to lower the punches to a low initial fill position, and a weight adjuster second cam adjustably mounted on the frame adjacent the first cam to subsequently raise the lower punches to a desired fill position, the improvement wherein at least a portion of the first cam proximate the weight adjuster second cam is supported on the frame by adjustable support means, said cams being also capable of relative adjustment.
7. A tablet-ting machine as described in claim 6 wherein the means for adjustably supporting the first cam portion 5 comprises a pair of spaced supports and means adapted to move the supports in unison to maintain the first cam portion in constant relation to the horizontal.
8. A tabletting machine as described in claim 7 wherein the means to move the supports in unison comprise rotatable threaded elements rotatably linked together.
9. A tabletting machine as described in claim 6 wherein a second portion of the first cam is disposed on the opposite side of the first portion from the weight adjuster cam, and the second portion is formed with a longitudinal recess and the first portion is formed with a tongue extending into the recess to provide a continuous lower limit for the lower punches.
10. A tabletting machine as described in claim 6 including means to operate the first cam portion and the weight adjuster cam in unison.
References Cited UNITED STATES PATENTS 2,043,085 6/1936 Westin et a1 107-17 2,218,913 10/ 1940 Hughes et al. 15-77 2,321,179 6/1943 Boyer 15-77 2,997,741 8/ 1961 Crossley 10717 X 3,029,752 4/1962 Frank 107-17 WALTER A. SCHEEL, Primary Examiner.
A. O. HENDERSON, Assistant Examiner.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2043085 *||Mar 7, 1934||Jun 2, 1936||Stokes Machine Co||Tablet machine|
|US2218913 *||Jan 18, 1938||Oct 22, 1940||Hughes John M||Apparatus for scrubbing and polishing strip metal|
|US2321179 *||Feb 25, 1941||Jun 8, 1943||Blaw Knox Co||Sheet-cleaning apparatus|
|US2997741 *||Jan 20, 1959||Aug 29, 1961||John Holroyd & Company Ltd||Rotary compacting machines|
|US3029752 *||Jul 20, 1959||Apr 17, 1962||Stokes F J Corp||Tablet making machine|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3924996 *||Nov 19, 1973||Dec 9, 1975||Jursakov Anatoly Illarionovich||Rotary tablet-making machine|
|US5211964 *||May 20, 1991||May 18, 1993||Westinghouse Electric Corp.||Press machine with means to adjust punching force|
|US5213818 *||May 17, 1991||May 25, 1993||I.M.A. Industria Machine Automatiche S.P.A.||Device for taking and conveying tablets coming out of a rotary tabletting machine|
|US5762978 *||Jul 31, 1995||Jun 9, 1998||I.M.A. Industria Macchine Automatiche S.P.A.||Batching device for tablets making compression machine|
|US7360483 *||Apr 12, 2007||Apr 22, 2008||Fette Gmbh||Device for the guidance of lower rams|
|US20070257411 *||Apr 12, 2007||Nov 8, 2007||Fette Gmbh||Device for the guidance of lower rams|
|U.S. Classification||425/345, 425/355, 425/350|
|International Classification||B30B11/02, B30B11/08|