CA1053183A - Dispensing and wiping device for stencil gasketing - Google Patents

Abstract

A B S T R A C T

A hand-held, manually-operated device for dispensing a viscous liquid in conjunction with a wiping action. Downward pressure on a handle causes expression of viscous material through one or more perforations or orifices in a flexible seal which is in abutting relationship with a surface to which the material is to be applied.
As the device is slid across such surface the flexible seal pro-vides both a sealing and a wiping action.

Description

~5~L83 BACKGROUND OF THE I~ ENTION
n recent years stenciled-on gaskets have reallzed increasing acceptance, replacing the previous d;e-cut gaskets. This new form of gasketing has been made possible largely through the availability of improved ~;
chemical sealant formulations which are capable o~ being pressed through a stencil to form an appropriate gasket pattern on a surface to be sealed, and are then curable to effect a satisfactory seal. Development of stencil gasketing has been delayed, however, by the unavailability of fully suitable application devices Accordîng to typical prior art procedures an excess of gasketing material is applied to the stencil and is then squeegeed in order to press it through the stencil and deposit it ;, . .
in gasket form on the surface to be sealed. This has ~-resulted in excessive use of material, with attendant loss of economy, and has also required a ~eparate wiping or ~;
squeegee operation. The present invention provides a device which simultaneously dispenses an appropriate amount~of gasketing material,~presses it through a ~-stencil, and wipes the stencil essentially clean without significant waste of material.
SUMMARY OF THE INVENTION
According to the invention there is provided a device .
for dispensing viscous material comprising a hollow tubular cGntainer containing the material to be dispensed;
a hollow kubular sleeve mounted slidably over the container' a ~eeding means mounted at one end of the sleeve and adapted to engage the container at one end and extend increasingly thereinto to cause the viscous material to be exuded from the containerr and an ~ .
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application means mounted on the end of the container remote from the feeding means to dispense the viscous material onto an abutting surface and wlpe said surface, ~:
said application means comprising an applicator head adapted to sealingly f it the end of the container and having a flexible lower surface with one or more perforations therethrough which communicate with the - interior of the container, and the flexible surface being :~
adapted to simultaneously seal against and wipe an -~ 10 abutting surface. The flexible surface may be fitted into ; or over the applicator head or may be integral with the applicator head, as in a unitary molding.
More specifically, there is provided a devi~e for dispensing viscou~ material comprising a hollow tubular ~, .
container containing the material to be dispensed; a `
hollow tubular sleeve fitting slidably over the container, on one end of which is mounted an advancing plunger~
assembly, the plunger of which engages the container at ~ ;
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~ one end and advances thereinto; an application means which .. ~;
fits sealingly on the other end of the container and comprises a unitary structure having a flexible lower surface with a central hole therethrough which communicates with the interior of the container, the flexible surface adapted to simul~aneously seal against and wipe an abutting surface According to the inventi~n there is also provided a . . , process for stencil gasketing comprising contacting the applicator head of the above devices with a stencil in abutting relationship with a surface to be gasketed, 30 depressing th~ handle, i.e., the sleeve, of the devices ;`~
and sliding ~he devices over the stencil, where~y

- 2 -Il ~0~3~83 viscous gaske1-ing Eluid is dispensed from the devices pressed through the stencil, and the stencil is simultaneously wiped.
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RIEF DESCRIPTION OF THE FIGURE

Figures 1 and 2 are assembly views of two possible embodi-ments.

I DETAILED DESCRIPTION OF THE INVENTION ¦

¦ The following description reers to Figure l. The material ¦17 to be dispensed is contained in a hollow, cylindrical tube or 'j ;
cartridge 2, having an inside diameter D2, which acts as a con-tainèr for the material. Slldably mounted over this container is a hollow, cylindrical sleeve 1 which also funotions as a handle ~ ~ ;
having a hand rest 19 and at one end of which sleeve is mounted a feeding mechanism comprising, typically, a plunger 5 and rod 3 assembly which is capabie of advancing under the action o~ a feeding ratchet 4. At~the end of the cor.tainer opposite~the feeding mechanism the;container engages a seal ring 7, having a~
shoulder 18,~ which prevents~leakage~o~ the material when extruding ~orce~;is applied to it and also~serves as a mounting member to I , support an appliaator head 8~on which is fixed a flexible seal 11 typically having a cixcular~configuration, and at least one per-foration preferably in its center. The single per~oration shown in~igure~l has a diameter Dl The applioator head is mounted ~to the seal~ring in~a;s;lidable manner b~ means of~a series of shou1der screws 9 on some~or all of which are mounted compression springs lG.~ The~applicator head and seal ring are designed so li ;;
~hat the applicator head can slide over the seal ring, bu~ the parts are designed such that when~-there is no compression force on !the~: spring, a small~gap I3 exists between facing surfaaes of the

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seal ring '~ and applicator head 14, respectively. The assembled combination of the seal ring and applicatox head comprise the ' "application means" of this embodiment.
In operation, rod 3 is advanced, whereby plunger 5 engages ~ ' ;~ seal 6 in the end of container 2 and ratchet mechanism 4 is en-gaged to prevent further motion of the rod. However, the plunger ~'~'` ' is not advanced to such an'extent that the material i~ driven ~rom the opposite end of the container and through the perforation or hole in the ~lexible seal 11~ ~he device is grasped by sleeve O or han~le 1 and held in flat, abutting relationship against a ¦ ' stenci} 12. Downward force! i.e., toward the stencil, is then ~ ' -applied manually to the slee~e or handle, which exerts sufficient compressive force on the material in the container to cause it to j ';
be exuded through the hole in the flexi~le seal. Thç downward I i ~ force also exerts compressi~e force on shoul~er 18, which force j ' ;
i compresses flexible seal 11 causing it to seal against stencil i2.
1' As material is exuded through the perforation the device is slid j ;~
or~ wiped across the stencil~, by~which action material is ~orced ~ ~hrough the perforations in the stencil, therehy forming a gasket 3 ~:
'~2Q ~ corresponding to the perforations in the stencil. The stencil is thereafter removed. The flexible seal acts as a wiper or a squeegee, thereby controlling ~he flow of the ma~erial and prevent-ing it from leaking and simultaneously wiping the stencil surface~
¦clean.'~Pressure on the handle overrides the effect o springs 10 '~
25 ~ ~ ~therèby compressing them and closing gap 13. When the device has ! ~`
been slid over the entire stencil surface, downward pressure on the handle is released at least partially~ and sufficiently to ' ~; p~rmit the springs to expand,'thereby~ restoring gap 13.~ ~his '~ ~ action permits the viscous material~to expand slightly which tends ~30 to relieve the exuding forces in the material thereby terminating ., :................................................ ~

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~05~1~3 !the expression of material through the per~orations in flexible !!
seal 11. Even after the partial release of pressure on the handle, there is sufficient pressure to maintain the flexible seal in flat abutting relationship with the stencil, whereby the i wiping and sealing action of the flexlble seal is maintained and ,the stencil surface is thereby kept clean and free of excess material.
As has been described, downward ~force on the sleeve on handle causes material to be e~pressed. In order to reset the handle for ~the next downward stroke, it is moved upward on the rod under the ¦
¦action of the ratchet. This manipulation does not change the position of the plunger in the container, so that seal 6 is left in contact with the material and ready for the next downstroke.
The size of gap 13 will be a function of the compressive ~15 forces generated in the material in the container, which stresses in turn will be a ~unction o~ such parametexs as the viscosity of ~ ~
¦ the material~ the inside diameter D2 Of the container and the ~ ;
¦diameter Dl of the perforation in the flexible seal. The thick'- ' ¦ness of gap 13 can be readily determined by simple experimentation. ~ ' However, as a general rule it is suggested that this gap be ' ¦ approximately 1/16 to 3/16 inch, preferably about 1/8 inch.
¦ Xn oxder to insure that the flexible seal properly seals to prevent material leakage, it is highly desirable that the flexible j seal contact the stencil or other surface be~ore material begins ~¦to be expressed. In order to accomplish this, the surface of the flexible seal should be raised slightly in the area surrounding the perforation or perforations in the ~lexible seal. While not I absolutely essentla1, sealing will be more efficiently accomplished if'the raised area is immediately adjacent to the perforation. j i 30 ¦ An alternative embodiment is illustrated in Figure 2. Like :~: I ! ~
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numerals correspond to like parts and functions as in Figure l.
The diference, however, is that in Figure ~ the seal riny, appli-cator head and flexible seal are eliminated as separate parts and instead are combined into a unitary molded application means 23 ¦ which fits snugly and sealingly over the end of aontainer 2. The 1exible seal against a stencil or other surface is provided by ¦lip 20 which is raised oVer surface 61. Edge ?2 is broken with ¦¦a radius. Angle A is preferably approximately 45. Because vf the elimination of mechanical parts, the application means of ¦-¦Figure 2 is more economical and preferred over that of Figure l; , ;~
~ ¦however, because of the elimination of the gap/spri.ng configura- ~ ;
.`: tion, the ormer is slightly more difficult to use with complete ~ efficiency~ It has been found, however, that the natural tenden~y ' i; of lip 20 to resume its raised position after downwaxd pressure L5 !on it is released~ tends to provide a similar expansion effect as ¦does the gap/spring Conriguration of ~igure ]. It has been found j ~ ;
~1 ~that With a little~practice, completely satisfactory results can , ,! ,~
;-1 : : be obtained with the embodiment of Figure 2. '~
; ~ The~flexible seal~ll or ~unitary seal 23 can be fabricated from any material which is flexible enough to provide an e~fective .~ seal and will not be chemically attacked by the material in the ¦
`~ container. Typical of suitable materials are butyl rubber, : silicone rubber and neoprene, silicone rubber being preferred.

~ The preferred~hardness of the flexible sea].ing material will be '25~ about 45 to 65 Durometer/ more preferably about 50 to 60 Durometer.
Below about 45 the flexible material tends to be pressed into the per~forations in the stencil, and above about 65 its sealing an~
wiping ability are reduced. : ~ :~

The materlal which~may be effectively dispensed by this device Will have a viscosity Varying from about~50~000 centipoises ,~' ~ ~ ~ - 6 - ~ `
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1(~531~3 to about lQ,000,000 cen~ipoises or more, preferably about 900,000 to about 8,000,000 centipoises. A particularly use~ul material is the anaerobic formulation taught by U. S. P~ 3,547,851.
It will, of course, be understood by those skilled in the ; art that substantial departures from the specific details of the figures can be made without departing from the scope and intent of this invention. For instance, a mechanism could be conceived whereby springs 10 axe placed in tension rather than in compression.
One could also visualize a device in which handle 1 is advanced L~ under pneumatic force continuousl~ rather than incrementally by !
hand. Similarly, flexible seal 11 could be stretched over appli cator head 8 rather than being recessed therein, as shown.
SLmilarly, the leng h of sleeve 1 and container 2 may be as long or short as d~sired.
It will be appreciated that the present device involves the balancing of a num~er of parameters in achieving its beneficial result of exuding viscous material and si~ultaneously sealing against its radial outward flow under the same downward force. ,~
, The optimum design in any particular instance will be arrived ~0 at by ~experimentO
The rat~io of D2 to Dl will affect the ability of the device to provide sufficient force to the seal area, e.g., lip 20. For most applications the ratio of D2 to Dl will be between about 1.1 and about 1.6, preferably between about 1.25 and about 1.45, and ! ~
more preferably between about 1.30 and about 1.40. The viscosity I I
of the material will affect the amount of dow~ward force needed for exudation and therefore the amount of force available for ~ ;
sealing. For instance, an especially low viscosity will require - ¦ I
~ ~ relatively little force, so that an eifective seal might not be formed. However, this~efect can be counteracted to a certain : ~ ,. ~: ~ '~
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extent by xeducing Dl, which tends to concentrate the sealing force available. Similarly, the hardness and configuration o l 1Ithe flexible seal will affect its ability to seal. rrhe hardness !
¦¦has already been discussed. I,ip 20 ma~ be raised from about 0.020 i1to about 0.070 inch or more, preferably from about 0.035 to about ¦~0.60 inch. It has been found that an improved seal capability jjwill bè obtained if edge 22 is hroken sliyhtly, as by, say, a ~radius of approximately 0.030 inch. q~he thickness of the flexible jseal or membran~ will vary depending primarily upon the material chosen for its fabrication and the design of the sealing area, i.e., the area surrounding the perforations. qlhe important con-siderations are that the membrane be suficiently thick to provide he necessary structural integrity but not so thick as to inter- j ere with flexibility. In general, the thickness in the area of ~;5 the per~orations may be a~out~l/16 to about 3/16 inch, preferably about 1/8 inch. ~ ; ~ ;
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Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A device for dispensing viscous material com-prising a hollow tubular container containing the material to be dispensed; a hollow tubular sleeve mounted slidably over the container; a feeding means mounted at one end of the sleeve and adapted to engage the container at one end and extend increasingly thereinto to cause the viscous material to be exuded from the container; and an application means mounted on the end of the container remote from the feeding means to dispense the viscous material onto an abutting surface and wipe said surface, said application means comprising an applicator head adapted to sealingly fit the end of the container and having a flexible lower surface with one or more perforations therethrough which communicate with the interior of the container, and the flexible surface being adapted to simultaneously seal against and wipe an abutting surface.

2. The device of claim 1 wherein the feeding means is an advancing plunger.

3. The device of claim 1 wherein the applicator head is spring-mounted thereby creating a gap when downward pressure on the sleeve is at least partially released.

4. The device of claim 1 wherein the flexible surface of the applicator head comprises a rubber.

5. The device of claim 4 wherein the area immediately surrounding a perforation is raised.

6. The device of claim 1 wherein the ratio of the inside diameter of the container to the diameter of the per-foration in the flexible surface is from about 1.1 to about 1.6.