US2531338A - Static neutralizer for tablet presses - Google Patents

Description

Nov. 21, 1950 F- A. LOBLEY ET AL STATIC NEUTRALIZER FOR TABLET PRESSES TABLfT PRESS OPERAT/NG MECHHNUM CAM ROTATES 0/vc F01? EACH OPEHAT/UN 0F PUNCH INSZ/L/J 7/0/v 55 Filed June 15 1948 INVENTORE.

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Patented Nov. 21, 1950 STATIC NEUTRALIZEB FORTABLET PRESSESv Frederick- A. Lobley and James A. Eost e r, Ellrhart,

Ind., assignors telvliles Laboratories, 1110-, Elk.- hart, Ind a corporation of Indiana Application June 15, 1948 Serial No. 33,174

7 Claims.

Qur invention relates, generally, to static neutralizers and it has particular relation to apparatus and methods for dissipating electrostatic charges from tablets formed on a tablet press.

It is well known to manufacture various tablets from the ingredients in powdered form by compacting the same in a tablet press. These materials ordinarily are electrical insulators when dry. ,As the tablets are discharged from the press, they move over the bottom surface of a discharge chute or slide in passing to a stacker or into bottles. In so doing they acquire electrostatic charges which, in many instances, cause them to stick in the chute or slide. The tablets then pile up and do notgreach the stacker or bottle.

Accordingly, among the objects of our invention are: To prevent tablets from sticking in a discharge chute or slide as they move away from a tablet press used for forming the same; to dissipate the electrostatic charges acquired by the tab lets; to generate an ionized atmosphere in the vicinity of each tablet to provide an electrically conducting path along which the charges on the tablets can flow to ground; and to synchronize the creation of the ionized atmosphere with the operation of the press so that each tablet is subjected individually thereto.

Other objects of our invention will, in part, be obvious and in part appear hereinafter.

Accordingly, our invention is disclosed in the embodiment thereof shown in the accompanying drawing and it comprises the features of con,- .struction, combination of elements, arrangement of parts, and method of operation which will be set forth in the description hereinafter and the scope of the application of which will be indicated in the appended claims.

Now, in order to provide a more complete understanding of the nature and scope of our invention, reference may be had to the following detailed description, taken together with the accompanying drawing in which the single figure illustrates, diagrammatically, a preferred embodiment of our invention.

Referring now to the drawing, it will be observed that the reference character I0 designates, generally, a tablet press of conventional construction which includes a punch ll that; is arranged togbe reciprocated vertically by the tablet press operating mechanism which is indicated at 1 2. The punch I l is movable downwardly with respect to a mould carrying base l3 for cooperating therewith to form tablets M from suitable dry powdered ingredients that inherently are electrical insulators. The tablets 14 after they are formed by the punch l I are discharged over a slide or chute ii to a stacker I6 and thence for packaging to a bottle H:. The apparatus and mechanism thus. far described .are conventional and well known in the art. ,Obviouslythe tablets i243 may be, disposed of otherwise than. by moving tothe stacker t6 and bottle IT; as describfid.

Difiiculty has been encountered in the f ai1nre of the tablets: J14 to slide freely down the chute l5. under the influence ofgravity. As a result. of their movement over the surface of the slide or chute-1:5 they tend topick up electrostatic charges which cause them to stick to the surface of the slide or chute l5. As a result the tablets. l4: tend to pile up on the slide or chute 15 instead of sliding freely down the, same as is required for the proper operation of the discharge mechanism from the tablet press t0".

With a view to dissipating the electrostatic charges which are acquired by the tablets {IA as they begin to slide down the slide or chute l5, we. have providedmeans for generating an ionized atmosphere around each of the tablets 4.4 so that a conducting path is provided over which the electrostatic charges acquired thereby can flow .to ground. For this purpose a, spark plug, shown generally at. 20, may be employed which has electrodes 2i and 22., The spark plu 28. may h a conventional automobile park plug as white-understood readily. A high voltageis employed f r ener izin the ele trodes 21 nd :22 so as to pro..- vide a, spark discharge which is indicated at '23 that creates the ionized atmosphere just referred to. It will be noted that spark discharge 23 is generated, in the vicinity of each of the tablets I4 as it begins to move down the slide or chute IS. The spark plug 20 includes a conventional base '24 from which the electrode 21 extends. -T-he means can be employed for s pplying the highvoltage for energizing the electrodes 2| and 22. As shown in. the draw n they ay be o c d by conductors ZBand 21 for energizationto a high vo tage secondary winding 2 o a transformer that s shown, generally, at .28.. Transionner 29 may have a primary winding 30 which may be energized from a source 3| of alternating current such as a 60 cycle 110 volt source. The source 3| may be connected to the primary winding 30 of the transformer 29 by conductors 32 and 33.

It is desirable to cause the spark discharge 23 to occur only during a brief interval, such as a fractional part of a second, as the tablets l4 start to move down the slide or chute [5, there being a spark discharge 23 individual to each of the tablets M. For this purpose a switch, shown generally at 34, is interposed in the conductor 32 as shown. The switch 34 includes a stationary contact 35 and a movable contact or arm 36. Normally the contact or arm 36 is biased by a coil compression spring 31 out of engagement with the stationary contact 35 so that the circuit to the primary winding 30 of the transformer 29 is opened. In order to close this circuit a cam 38 is provided which, as shown, is arranged to engage the movable contact or arm 36 and move it into engagement with the stationary contact 35. When the circuit is completed in the manner .just described, the primary winding 30 is energized and a high voltage is generated in the secondary high vo tage winding 28 which is applied across the electrodes 21 and 22; the air gap therebetween is broken down and the spark discharge 23 takes place.

As indicated hereinbefore, it is desirable that the spark discharge 23 be synchronized with the movement of the tablets l4 so that the ionized atmosphere will be created for each of the tablets l4. Accordingly the cam 38 may be driven, as indicated by the broken line 39, by the tablet press operating mechanism l2. It will be understood that the cam 38 rotates once for each operation of the punch H so that the spark discharge 23 is caused as each tablet (4 moves past the air gap between the electrodes 2| and 22.

The generation of the ionized atmosphere by the spark discharge 23 provides a conducting path to ground so that the electrostatic charges which have been acquired by the tablets M can fiow over this path and be dissipated.

It has been found that a static charge frequently is induced into the tablets l4 during the compression of the material forming the same. This charge is dissipated by the ionized atmosphere that is created in the manner described.

If desired, the electrode 21 can be omitted. In such case the spark discharge 23 is between the center electrode 22 and the base 24. The spark discharge 23 may then be from inch to inch long and may occur between the electrode 22 and any point around the base 24m thus extending the ionized space over a larger area and effecting more complete neutralization.

Since certain changes can be made in the foregoing construction and different embodiments of the invention can be made without departing from the spirit and scope thereof as well as somewhat different method steps can be followed, it is intended that all matter shown in the accompanying drawing and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In combination, a tablet press having mechanism for forming tablets and a slide down which the tablets move after being formed for packaging in a container or the like and along which they are likely to stick as a result of their acquiring an electrostatic charge, electrode means in insulated spaced relation providing an air gap adjacent said slide at a location where each tablet starts to move down the same, circuit means for connecting said electrode means for energization to a source of high voltage to cause an electrical discharge across said air gap and thereby dissipate said electrostatic charge from the adjacent tablet whereupon it moves freely down saidslide, switch means interposed in said circuit means, and mechanism operatively interconnecting said tablet forming mechanism and said switch means for operating the latter to cause said electrical discharge each time that a tablet is formed.

2. In combination, a tablet press having mechanism for forming tablets and a slide down which the tablets move after bein formed for packaging in a container or the like and along which they'are likely to stick as a result of their acquiring an electrostatic charge, electrode means in insulated spaced relation providing an air gap adjacent said slide at a location where each tablet starts to move down the same, circuit means for connecting said electrode means for energization to a source of high voltage to cause an electrical discharge across said air gap and thereby dissipate said electrostatic charge from the adjacent tablet "hereupon it moves freely down said slide, normally open switch means interposed in said circuit means, and a cam operatively related to said switch means for closing the same, said cam being driven by said tablet forming mechanism to close said switch means each time that a tablet is formed.

3. In apparatus of the character described, a tablet press and discharge means therefor, means providing a spark gap at said discharge means, and circuit means operated in timed relation to the operation of said press and connected to said spark gap means effective for causing sparking across said gap when a tablet is discharged from said press.

l. In apparatus of the character described, a tablet press and discharge means therefor; insulated electrodes providing a spark gap at said discharge means, and circuit means operated in timed relation to the operation of said press and connected to said electrodes effective for causing sparking across said gap when a tablet is discharged from said press.

5. In apparatus of the character described, a tablet press and discharge means therefor, insulated electrodes providing a spark gap at said discharge means, circuit means connected to said electrodes eilective to cause a spark to jump across said gap, normally open switch means interposed in said circuit means, and operating connections between said switch means and press effective for closing said switch means when a tablet is discharged from said press.

6. In apparatus of the character described, a tablet press and discharge means therefor, means provir'ing a spark gap adjacent the point of discharge of the tablets efiective for creating an ionized atmosphere about the respective tablets as they are discharged from the press, and means controlled by said press efiective for causing discharge of a spark across said gap responsive to discharge of a tablet from the press.

'7. In apparatus of the character described, a tablet press and discharge means therefor comprising an inclined slide down which the tablets are delivered, means providing a spark gap adia- 2,581,838 5 6 cent the upper end of said slide effective for cre- REFERENCES CITED ating an ionized atmosphere about the respective The following references are of record m the tablets as they enter upon the slide, and means me of this patent: controlled by said press effective for causing discharge of a spark across said gap responsive to 5 UNITED STATES PATENTS discharge of a tablet from the press. Number Name Date 1,262,173 Chapman Apr. 9, 1918 FREDERICK A. LOBLEY. 1,394,064 Chapman Oct. 18, 1921 JAMES A. FOSTER. 1,678,869 Morrison July 31, 1928

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