US3318265A - Tablet punch assembly - Google Patents

Description

y 9, 1967 E. P. WINTERS ETAL 3,318,265

TABLET PUNCH AS SEMBLY 2 Sheets-Sheet 1 Filed March 16, 1964 5 m L 3 Z; 4 r {m W0; 8 N H| I 6 4 MW JW! 3% g g 1 .HH ff j M z w? M f 1. 1g l/ l| I, W T ow raw h w/ m i w, 3 WW w WHJFU H W fi H n 1 f i .I wfl w I j 1 y 1967 E. P. WINTERS EITAL 3,318,265

TABLET PUNCH ASSEMBLY Filed March 16, 1964 2 Sheets-Sheet 2 Robert 5. Brahman dfiwvzeg United States Patent Ofiice 3,318,265 Patented May 9, 1967 3,318,265 TABLET PUNCH ASSEMBLY Edward P. Winters, Waukegan, and Whitney L. Pearson, Lake Bluff, 111., assignors to Abbott Laboratories, North Chicago, 111., a corporation of Iilinois Filed Mar. 16, 1964, Ser. No. 352,012 1 Claim. (Cl. 107-17) This invention relates to an improvement in tabletting machines, and more specifically to a keyed upper punch and head construction whereby a keyed upper punch head may be quickly, easily and accurately rotatably adjusted.

Most conventional tabletting machines utilize upper tablet punches which are reciprocably, non-rotatably mounted in the head of the machine. Such tablet punches are maintained in fixed relationship to the head of the machine by virtue of a key machined in the punch which slides in an appropriate keyway in the machine head.

In adjusting a machine to produce differently-shaped non-circular tablets, it is necessary to adjust the relative position of the punch head with respect to the machine head. This relationship is critical in order to avoid tablet breakage and punch and die Wear. Adjustment of the relationship of the punch head with respect to the machine head has heretofore been accomplished by removal of the key and brazing a new key to the punch body in different positions until the proper position of the punch with respect to the machine head is located. This process of key removal and brazing is extremely time-consuming and therefore unsatisfactory and contributes considerably to the period of several days to weeks which may be expended in adjusting a multiple-punch machine. Damage to the punch sometimes occurs during this procedure. Since tabletting machines have an average of about twenty-seven punch sets, and since the upper punch of each set must be separately adjusted, the dis-economies of this prior art construction will be readily appreciated.

Applicants invention overcomes these objections and enables punch heads to be readily manually adjusted with respect to the machine head. In a preferred embodiment of the invention, each tablet punch is reciprocably, nonrotatably mounted in a bushing; each bushing is rotatably mounted in a corresponding bore in the machine head, and means are provided for manually fixing each bushing in any desired position of rotation.

It is therefore an object of this invention to provide a tablet punch and machine head construction whereby the tablet punch heads can be accurately and easily rotated to any desired position and subsequently locked with respect to the machine head.

A further object of this invention is to provide manually operable means for easily and accurately rotating a tablet punch head with respect to the machine head.

Yet another object of this invention is to provide an improved tabletting machine head and upper punch construction.

A concomitant object of this invention is to provide a tablet punch mounting which may be manually secured and released and rotated through any angle.

Further objects and attendant advantages of the present invention will be apparent from the following detailed description, reference being had to the accompanying drawings, wherein a preferred embodiment of the invention, and several alternative embodiments, are clearly shown.

In the drawings:

FIGURE 1 is a perspective view of a conventional tabletting machine embodying the instant invention;

FIGURE 2 is a partial sectional view of a preferred embodiment of the tablet punch assembly of this invention;

I FIGURE 3 is a sectional view taken along line 3.-3 of FIGURE 2;

FIGURE 4 is a partial sectional view of an alternative embodiment of this invention;

FIGURE 5 is a partial sectional view of another embodiment of this invention;

FIGURE 6 is a sectional view taken along line 66 of FIGURE 5; and

FIGURE 7 is a partial sectional view of yet another embodiment of this invention.

Referring to the drawings, FIGURES 1, 2 and 3 show a conventional rotary tabletting machine comprising a 'base 29, a circular die table 10, an upper head 11, a feed hopper 44 and a discharge chute 40. Drive means (not shown) rotate circular die table 10 through peripheral gear teeth 36 in the direction of arrows of FIGURE 1 during normal operation of the machine. As can be readily seen, a multiplicity of dies 12 are peripherally located in corresponding bores in the die table. A threaded bore 34 is associated with each die 12, and a set screw 33 is seated in each bore 34 to releasably frictionably engage the outer surface of each die 12 to hold the die in a fixed position. The center of each die has a vertically extending molding aperture 32 which, for purposes of the instant invention, would normally have a non-circular cross section.

Cam 30 is mounted on the upper face of base 29. Lower tablet punches 35 are seated on the upper face of base 29, there being one punch corresponding to each die. The tip of each lower tablet punch 35 has a crosssectional shape corresponding to that of aperture 32 and the distal end thereof is always at least partially extending into aperture 32. As the circular die table rotates, the proximal ends of the tablet punches 35 are acted upon by stationary cam 30 to raise the punches sequentially into the corresponding apertures in which they are seated, and subsequently to lower them from the aperture. At the apogee of its travel the distal end face of each punch 35 extends approximately to the upper face of die 12.

Referring now especially to FIGURE 2, upper head 11 has a multiplicity of vertically extending peripherally spaced bores 18 formed therein. The spacing between the bores 18 is equal to the spacing between dies 12, and bores '18 and dies 12 are in axial alignment. A cylindrical bushing 13 of approximately the same diameter as each bore 18 is located in the corresponding bore 18 and is adapted to rotate therein. A peripheral groove 17 is located on the outer face of each bushing 13. A threaded bore 15 corresponding to each bushing 13 extends from outer peripheral face 22 of upper head 11 to the respective bore 18, and the peripheral groove 17 is adapted to be aligned therewith. A set screw 14 having a head 16 is seated in each threaded bore 15 and is adapted to releasably frictionally engage a segment of a corresponding peripheral groove 17 of the corresponding bushing 13. A centrally located, vertically extending, circular bore 25 is located in each bushing 13, and a vertically extending keyway 26 communicates with each bore 25 and is coextensive therewith. An upper punch 19 having a body portion 20, a punch head 27, and a punch tip 21 has a key 23 locked or similarly secured to body portion 20. Body portion 2!),has a circular crosssectional shape of approximately the same dimensions as bore 25 and key 23 is normally seated in keyway 26 so that upper punch 19 will not rotate in bore 25, while it may readily be reciprocated by the action of cam 28.

Cover plates 42 and 43 are shown in FIGURE 1 as being swung away from the tabletting machine, but it is to be understood that in normal operation in the machine the cover plates would surround the tablet punching mechanism shown. A hopper 44 is mounted on the machine and is filled with granulated medicament P strike the take-01f plate at an improper angle.

which is adapted to be discharged in metered amounts into each aperture 32 as the respective die opening passes below the hopper discharge outlet. Cam 28 is of such shape that when this occurs, the upper punch 19 is completely withdrawn from aperture 32.

It is to be recalled that in normal operation of the machine, at least part of the head of tablet punch 35 is always extending into the aperture 32, so that the lower 'motion discharging the compressed tablet T on to the upper face of die 12, from which it is swept off by take-off plate 41,onto discharge chute 40. The tips of punches '19 and 35 and aperture 32 have approximately the same cross-sectional dimensions to produce a tablet of the desired shape.

In normal operation of tabletting machines of this type, whenv producing tablets of non-circular cross-sectional" shape, the relative position of the punches, the die and take-off plate 41 is critical. Because of the force of cam 28 upon upper punch 19, it is apparent that each upper punch must be accurately located with respect to the corresponding mold opening to prevent any. contact between the bottom face of the upper punch tip and the top face of the die. Should the upper punch tip and the diebe slightly misaligned, the resulting forces when the punch is driven down into the die would result in chipping or breaking of the punch tip, necessitating replacement thereof. Since tablet punches are rather expensive, this is obviously an undesirable result. Furthermore, since the compressed tablet is a rather fragile article, theangle at which each tablet impinges upon the take-off plate is important, since tablets will crack and-be wasted if they Proper angular location of the punch tips can only be determined by trial and error for specific tabletfshapes, and consequently, each punch and die set must be independently adjusted. The die is adjusted by manually loosening set.

screw 33 and rotating the die 12.

Upper punches-have theretofore been adjusted by re- 1 moving the key 23, brazing itat a different angularlocation on'bodyportion 20 and repeatedly removing and remounting the key 23 until the appropriate relationships are determined. Since the machine accuracy in forming dies and punches is not perfect, the relative positionof a one punch and .die. set may'not apply for another punch and die set designedto produce the same shape of tablets.

In the instant invention, set screw 14 is loosened so that bushing .13 may .be rotated to adjust the relative position of upper punch tip 21 with respect to the upper head 11 of the tablet machine. The head 16 of the set screw 14 frictionally engages a segment of peripheral groove 17, so that bushing 13 is securely held in place. Tightening and loosening of set screw 14 thereby permits rotation of the tablet punch to any desired position.

To facilitate adjustment ofeach individual punchand to provide a guide for adjusting other punches of the machine, the upper face of the upper head 11 of the machine may be provided with numbered graduations 38 peripherally surrounding each bore 18," and each bushing 13 may be provided with a groove 39 to permit measuring of the angular position of the punch. If the bore 25 of a given bushing 13 wears excessively, the bushing may be replaced without necessitating replacement of the head 11.

A further embodiment of the invention is illustrated in FIGURES 5 and 6 wherein bushing 13" is provided with a non-circular bore 25" such as the square bore illustrated in FIGURE 6, and the body portion 20" of upper tablet punch 19" has a corresponding square cross-sectional shape, thereby eliminating the need for a key fastened to the punch body and a keyway formed in the bushing.

A further modification of the invention is illustrated in FIGURE 4 wherein the function of the bushing is replaced by having a bore 53 formed in the lower face portion of the body of upper punch 19. The punch 19' has a separate punch tip 21 which has a peripheral groove 50 formed proximate the upper end thereof. A threaded bore 52 is formed in the punch body communicating the bore 53 with the peripheral face of the punch body. A set screw 51 is seated in threaded bore 52 and the head of the set screw is adapted to frictionally engage a portion of peripheral groove 50 to rigidly secure tip 21' in bore 53. The angular position of tip 21" may thereby be adjusted by loosening set screw 51 and rotating the tip 21.

A further embodiment of the invention is shown in FIGURE 7 wherein upper tablet punch 19" comprises over neck portion 57 and set screw 56 is seated in.

threaded bore 62 of the collar; the head of the set screw 56 is adapted to frictionally engage a segment of peripheral groove 58. The relative position of punch tip 21 with respect to head 11' is accomplished by removing the tablet punch 19", loosening set screw 56, and rotating punch body portion 60 with respect to collar 55.

It will be appreciated that various modifications of the disclosed embodiments can beeflected without departing from the spirit and scope of the invention.

Having thus described-our invention, what is claimed is:

A rotary tabletting machine comprising an upper head, a bore defined by said upper head extending vertically therethrough and including a keyway, a tablet punch including a punch body, a neck, and a punch tip, a peripheral groove defined by said neck, a key member including a 'key seated in said keyway and a collar encompassing said neck and means mounted on said collar in engagement with a portion of said peripheral groove and rotatably adjustably mounting said neck in said collar.

References Cited by the Examiner BILLY I. WILHITE, Primary Examiner.

WALTER A. SCI-IEEL, Examiner,

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