US3533360A - Upper punch socket seal for rotary tableting presses - Google Patents

Description

United States Patent I72] 1m entor Walter R. Kibhe 4655 & 57 Oakland St.. Philadelphia. Pennsylvania 19124 Y [21 1 Appl. No. 695,933 122] Filed Jan.5, 1968 {45] Patented Oct. 13. 1970 [54] UPPER PUNCH SOCKET SEAL FOR ROTARY TABLETING PRESSES 4 Claims, 5 Drawing Figs.

[$2] L'.S.Cl [07/17, 7 25/102. 18/20 1511 Int. Cl B301) 11/08 50] Field of Search 25/102;

18/2()(T):107/14.14.2.15,16.17;BIZ-13.2565

{56] References Cited UNITED STATES PATENTS 532.794 5/1897 Noyes 107/17 ref/8,486 2/1908 Crowcll 15/248 1 1186.676 2/1914 Linscott l5/248X 2.612.894 10 1952 Akins 15/248X 3.266.810 8 1966 Reeser 15/256.5X FOREIGN PATENTS 496.585 4/1930 Germany 107/140.)

Primary Examiner- Laverne D. Geiger Assistant Examiner-R0bert 1. Smith Atmmey- Charles R. Fay

ABSTRACT: A seal for the upper punch sockets of rotary tableting presses. the seal comprising two main parts. a punch drip cup which is attached to the moving punch. and an obsorptive sealing ring which is attached in fixed position to the underside of the upper turret in a position surrounding the punch for the purpose of preventing product dust. lubrication. etc. from contaminating the material being tableted. wherein the absorptive sealing ring wipes the entire exposed portion of the shank of the punch as the punch moves upwardly. the wiped material automatically being disposed in the-drip cup. the latter substantially enclosing the absorptive sealing ring at the uppermost point in the cycle of the punch.

The drip cup has a special formation which in the downwardmost position of the punch forces the puffing dust outward for pickup by the usual dust-collecting nozzle.

UPPER PUNCH SOCKET SEAL FOR ROTARY TA'BLETING masses BACKGROUND OF THE INVENTION In tableting pharmaceutical products and particularly withvery fine dry powder, etc., dark specks and dirt flake down from the upper punch sockets and contaminate the product. With the development 'of modern-day high-speed rotary presses, this defect has become more apparent sincethe high- 'speed'turret products more air turbulence, dust and static electricity. The product dust works into the upper punch sockets and becomes discolored with or even without the' punch lubricant, and then in the vertical reciprocation of the punches, flakes down onto the product.

This condition dictates a high frequency of cleaning tablet- DESCRIPTION OF THE PREFERRED EMBODIMENT'OF THE i vENr oN a tool or punch 24 at the'lower end thereof which on the coming presses and the punches and dies, with a downtime of from two to six hours. Sometimes a serious condition will develop in fifteen to thirty minutes and operators are reluctant to provide adequate lubrication for this reason. It will be seen that a very serious problem obtains in this specific situation, including damage to machines and tools.

It is the general object of the present invention to provide a new combined absorptive seal and new special drip cup obviating the above difficulties. With the present invention it has been found that the tableting machine can run from threeand-a-half to four weeks without extensive cleaning and without product contamination, and even after such extensive use it is found that the seals are not worn and there are no signs of dust in the punch sockets or any traces of upper punch lubricant on the outside of the seal.

There have been many efforts to overcome this condition including O-rings, bellows, etc. but these are not successful. Where a tight seal is used, the hard wiping action thereof causes discoloration of the product dust which clings to the exposed portion of the upper punch shank due to static electricity. and prior art standard upper punch dust or drip cups are of little or no value withmost products.

SUMMARY OF THE iNvENrioN In the present case, an absorptive seal such as for instance felt is secured to the under side of the upper turret and surrounding each punchsocket, the inside diameter of this sealing ring fitting snugly about the shank of the upper punch. wiping the same clean at each reciprocation.

This is provided in cooperation with a special new and improved upper punch drip cup which fits tightly on the punch part of the upper punch shank and moves with the upper punch.

During the operation of the machine the sealing ring wipes the exposed portion of the shank and disposes of the residue into the new upper punch drip cup. The cup also closes off the upper punch socket at the dusty feed frame areav BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in elevation with parts in section illustrating the invention as applied to an upper punch in the upper turret of a tableting machine, and showing the machine at the filling station and at the highest position of the upper punch;

FIG. 2 is a similar view showing the upper punch at the com pression part of the cycle thereof, i.e., in its lowermost position;

FIG. 3 is a section on line 3-3 of FIG. 2;

FIG. 4 is a top plan view of the drip cup, and

FIG. 5 is a view in elevation thereof, with parts in section.

'pression stroke as shown in FIG. Z'enters the passage I8 in which are the usual dies in which the tablet is formed by the punches. I

As so far described, this machine is old and well known, the upper. and lower pressure rolls as at 26 and 28 causing the punches to approach each other from their extreme separated position, FIG. I. to their most extreme compressive position,

FIG. 2, the tablet being formed in the area which is indicated in FIG. 2 at 30, in the usual die, not shown, but well understood in the art.

As indicated above, production of these machines is greatly .limited by the fact that the powder which is tableted, and especially the finer powders, tend to be scattered to a small extent in the atmosphere and are attracted to the upper punch shank both by static electricity and by the small amount of lubrication necessary for the continued smooth operation, and the present invention provides means for obviating this difficulty.

An absorptive member 32 which is conveniently made of felt in the form of an annular ring, see FIG. 3, is adhesively or otherwise secured to the underneath surface 34 of the upper turret which is indicated at 36, the lower turret being indicated at 38. This seal is in effect in fixed position and snugly fits the punch shank 22, and as the'shank reciprocates in its socket 40 on its upward stroke for instance, any detritus on the shank is wiped off by this sealing'ring.

A large portion of the punch shank is exposed as shown in FIG. 2 and the product dust tends to cling to this area. As the upper punch is moved upwardly to its highest position above the feed frame or at the fill station, and the new sealing ring wipes the entire exposed portion of the shank, the detritus drops into the novelupper punch drip cup, the latter being generally indicated by the reference numeral 42. The machine can thus be operated for long periods of time, it only being necessary to clean the cup 42 which takes a minute or two, avoiding the prior art downtime of several hours as explained above.

At its uppermost position, see-FIG. I, the drip cup closes off the upper punch socket 40 which reciprocates at the dusty feed frame area, thus enhancing the beneficial effects of the construction by keeping dust out of the socket.

The drip cups ofthe present invention are of relatively large diameter and flat-bottomed, see particularly FIG. 5, and are fixedly secured to the respective punch at the area shown, so that the punch 24 is exposed for disposition in the die, see FIG. 2, but at the same time the cup completely surrounds the same and the lower portion of the shank portion 40.

Due to the flat bottom and the extra large diameter of the novel drip cup, any puffing dust compression is forced outwardly for pickup by the usual dust collecting nozzle, not shown; whereas conventional small diameter and rounded bottom drip cups tend to force the puffing dust upward rather than outward for even greater accumulation on theupper punch shank and the upper punch sockets. The new drip cup has a central opening, 44 surrounded by a gasket 46 which dust which has been found to improve the sealing action due I to the fact that the rings are absorbent. These rings are of course very inexpensive and are easily replaced. e.g. upon change over to another product. Y

The dual function of keeping necessary punch lubricant in the upper punch sockets while keeping the dust out of the punch sockets, insures smoother machine performance for extended operating periods without product contamination. and the operator then sees that sufficient lubrication is applied to keep the machine running smoothly.

l claim:

1. ln a rotary tableting press having an upper turret. a series of sockets in the turret. a reciprocal punch in each socket, a filling station in generally fixed position. the punches passing the filling station seriatim in the operation of the press, the press including a die table and a lower punch.

that improvement which comprises wiping means on the upper turret substantially surrounding each upper punch socket at the under side surface of the upper turret. said wiping means being in wiping engagement with the respective upper punches wiping detritus from the punches during the motion thereof with respect to the upper turret. and a drip cup on each upper punch and moving therewith, each cup being in a position to receive the detritus wiped from its punch.

Y 2. The rotary tableting press recited in claim I wherein the wiping means comprises sealing rings.

3. The rotary tableting press recited in claim I. wherein the wiping means comprises sealing rings and each drip cup has a diameter greater than its sealing ring.

4. The rotary tableting press recited in claim 1. wherein the wiping means comprises sealing rings and each drip cup has a diameter greater than its sealing ring. and in the upwardmost position ofthe punches substantially enclosing each respective sealing ring and thereby closing off the respective upper punch socket to prevent the entrance of circumambient contamination.

1 FORM Po-mso (10-59) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. Dated dot. 13, 1970 Walter R. Kibbe Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, after the name and address of the inventor, the following should appear:

Assignor to Sterling Drug Inc., New York, New York, a corporation of the State of Delaware slam min MALE!) Aneat:

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