Hand-held Electric Caulking Gun

Abstract

This invention relates generally to caulking apparatus and particularly to a hand-held electric caulking gun adapted for receiving therein a caulking cartridge and operable upon the closing of an electric trigger switch, to dispense the caulking from the cartridge with considerable force and in a continuous easy-to-control flow.

Description

Caulking guns are well known in the art and are designed primarily for dispensing caulking that comes prepackaged within a cylindrical-like container or cartridge having projecting therefrom a dispensing nozzle through which the caulking is forced during the caulking operation. These guns include a receptacle wherein is received the cartridge with means being provided for driving a piston-like member through the cartridge thusly forcing the caulking from the nozzle.

Generally the piston of such apparatus is driven by variously constructed hand operated leverage mechanisms which serve to multiply the force applied, to more easily urge the piston through the cartridge. It is well known, however, that even with the mechanical advantage offered by such force multiplying mechanisms the effort required to drive the piston is considerable and frequently beyond the gripping capability of many, particularly the aged or those crippled as with arthritis or the like. Yet in many instances the very livelihood of such individuals with trades such as painters, boatmen and general home repairmen depend upon operating such caulking guns.

It is the primary object of the present invention to provide an electric hand-held type caulking gun wherein the power required to drive the piston through the gun is applied by means of an electric motor which, by the closing of an electric switch, will enable even a child to dispense caulking of the most viscous composition and in a continuous, easy-to-control flow, and in a manner unobtainable with conventional hand operated apparatus of this type.

It is a further object to provide a caulking gun of the type herein described wherein upon emptying of the caulking cartridge or upon any other form of interrupted forward movement of the driven piston, a clutching mechanism disengages the driving mechanism from the piston thereby preventing damage to the driving train mechanism of the device.

Another object is to provide an electric caulking gun wherein reversing of the motor drive of the gun will withdraw the piston from the cartridge case to permit insertion of another filled cartridge within the gun.

A still further object is to provide an electric caulking gun wherein the electric drive includes a variable speed control that will allow fast or slow dispensing of the caulking from the caulking cartridge as desired.

A further object is to provide an electric caulking gun including quick disengagement of the drive linkage from the piston afer emptying of the cartridge thereby allowing the piston to be quickly retracted manually for insertion of another caulking cartridge within the gun.

Another object is to provide an electric caulking gun which, when in operation, dispenses the caulking from the gun with considerable force and in a manner to more positively penetrate such cracks and crevices into which the caulking is intended to flow and in a manner totally unobtainable by hand operated apparatus.

It is further desired to provide an electric hand-held caulking gun rugged in construction for professional use yet relatively inexpensive to produce .

Other objects and advantages will become more apparent when referring to accompanying description and drawings wherein:

FIG. 1 is a plan view partly cut-away of the assembled device of the invention.

FIG. 2 is a cross-sectional view through the gun receptacle and showing in elevation the gear housing cover of the device,

FIG. 3 is a fragmentary rear view of the caulking gun assembly.

FIG. 4 is a fragmentary view partly in elevation of the rear housing showing in elevation the clutching mechanism of the device.

FIG. 5 is a fragmentary view partly in elevation and partly in cross-section of the piston driving and releasing mechanism of the device.

FIG. 6 is a rear plan view of the segmented nut as assembled within the piston driving member of the device.

FIG. 7 is a fragmentary cross-sectional view of an alternate form of the rear housing cover plate.

FIG. 8 is a view in elevation of an alternate arrangement of the segmented nut of the assembly.

Referring now to FIG. 1, the device of the present invention is shown as comprised of a caulking cartridge receptacle 1 as mounted upon and secured by screws 2 to the piston driving portion of the device. The motor drive of the mechanism is contained within the housing 3 mounted conventionally to handle 4 with power being supplied to the motor by way of the supply cord 5. A trigger 6 operates an internal switch in the motor circuit which, when closed, puts the motor in operation. Operation of the motor drives the gear train of the device, a portion of which is shown as arranged within the front housing 7. The gear train reduces the motor speed to that desired to drive the piston 8 of the device through a caulking cartridge at a preferable rate of from 1 to 1-1/2 inches per minute. This rate of piston movement will dispense caulking from the cartridge at a continuous easy-to-control flow and at the necessary applying pressure. A conventional variable speed electronic control within the motor circuit, and as operated by the trigger 7, will greatly expand the versatility of the gun and its handling of caulking compounds of widely varying viscosities, however, a fixed speed drive will be found completely satisfactory.

Shaft 9, upon which is formed gear 10, delivers power from the power source and forward gear portion of the gear train, to gear 11 that is arranged to rotate freely about the piston 8. As shown in FIG. 5, an extension on gear 11 is so disposed as to journal within an annular guide 12 provided therefor within the inner face of the rear housing 13. Gear member 11 is formed preferably from plastic and so molded as to include a series of teeth 14, as shown to advantage in FIG. 4, that are arranged to mesh with similarily formed teeth provided within a similarily molded plastic drive member 15. These teeth are maintained in tightly meshing rotation by means of an annular corrigated spring washer 16 that presses the members 11 and 15 together in driving relation with respect to each other while pressing the assembly against shoulder 17 formed upon the inner face of the rear housing cover 18. This assembly will hereandafter be referred to as the clutching mechanism of the device.

Upon an overloading of the drive member 15 as by stopping of the piston during operation of the motor drive, the teeth on gear 11 are camed from those on the drive member 15 by compressing spring 16 sufficiently to allow slippage between the teeth of the clutch until such time as power to the drive train is interrupted or the piston freed. Within the device any suitable washer or arrangement of washers shall be provided between fixed and moving parts in accordance with good design practice. Since the gear 11 and drive member 15 are relatively slow moving parts, very little lubrication is required at their bearing surfaces.

Forced by clamp screw 20 within the drive member 15, is a conical like internally threaded segmented nut 21 having thereon extending flanges 22 that engage in driving relation similarly formed grooves provided therefor within the member 15 and as shown to advantage in FIG. 6. By reason of the tapered configeration of the nut 21, as it is forced by the clamp screw 20 into the drive member 15, the threaded segments of the nut are compressed about the threaded surface of the piston in a manner to drive the latter through the gun as member 15 is rotated by way of the drive train.

Interpositioned between the nut 21 and clamp screw 20 is a hardened washer 23 which, during operation of the gun, acts as a thrust-bearing and against which nut 21 bears after tightening of the clamp screw. Tightening of the clamp screw, forces the clutch assembly against spring 16 and slightly from its bearing contact against flange 17. Washer 23 includes an internal tab, not shown, that rides within the longitudinal groove 24 within the piston the tab serving to prevent rotation of the washer with the drive member 15 as the latter forces the piston through the gun. A relatively light spring 25 interposed between the washer 23 and the rear housing cover 18 maintains the washer positively positioned against the nut 21 after backing off of the clamp screw 20. Forward and backward movement of the clamp screw 20 is limited by the ring clamp 26 and the external knurled flange 27, however, here suitable shim washers may be provided about the clamp screw to more closely control axial movement of the screw.

Arranged within annular grooves provided about the segmented nut 21 as shown, are ring springs 28 that maintain the nut segments properly positioned axially with respect to each other while yieldably allowing separation of the nut segments from the piston threads as the nut is drawn backward with the piston after loosening of the clamp screw 20 as will hereafter be more fully described.

A set screw 30, threaded with the rear housing 13 as shown, is positioned to engage the longitudinal groove 24 within the piston to thereby prevent rotation of the piston as the latter is driven through the gun by rotation of the drive member 15.

FIG. 7 shows a variation of the rear housing cover 18 wherein an extending inner flange 31 serves to laterally support and thereby to provide an annular bearing surface for the drive member 15.

In FIG. 8 is shown an alternate arrangement of the segmented nut 21 wherein annular flat cut washers 32 are loosely arranged about the segments of the nut in a manner to closely bear against the sides of the grooves 33 in a manner to maintain the nut segments axially against thread misalignment while allowing relatively free movement of the nut segments radially. The clamp screw, washer and spring are as shown and previously described in FIG. 5.

To operate the gun as hereinbefore described, the clamp screw 20 is first backed off to allow manual withdrawal of the piston 8 from the cartridge receptacle 1. Retraction of the piston is done by means of the handle portion 36. As the piston is drawn backward through the receptacle, the threads of the piston, normally in mesh with the internal threads of nut 21, pulls the nut from its clamped position within the drive member 15 and outwardly against the retracted clamp screw 20. Upon movement of the nut sufficiently from its confines within the drive member and against the clamp screw the threads of the piston operate to cam the nut segments apart to allow slippage of the threads of the piston by the internal threads of the nut as the piston is in this manner quickly withdrawn from the cartridge receptacle portion of the gun. After insertion of a filled cartridge, the clamp screw 20 is again tightened to drive the nut 21 back into the drive member 15 and into thread meshing relation about the piston to again connect the piston with the drive train mechanism of the device. Any misalignment of the threads of the nut with those of the piston occurring at this time will be taken up by a shifting of the clutch assembly against spring 16. Subsequent rotation of the clutch assembly by the drive mechanism, will cause the threaded nut segments to snap again into meshing thread driving relation with the threaded surface of the piston.

As the piston dispenses caulking from the cartridge to ultimately reach its extreme forward position or is otherwise restrained from movement, the teeth of gear 11 are camed from those of the drive member 15 to allow slippage between the drive and the piston thusly preventing damage to the drive train of the device.

While the structure herein shown provides for quick manual withdrawal of the piston for insertion of a caulking cartridge, the motor of the drive is reversible to allow power withdrawal of the piston. However, it must be understood that the 5 to 6 minutes reverse running time of the motor drive, that is required to retract the piston, would be considered prohibitive to the average professional workman to whom time is a major factor.

Further, it is understood that a suitable gear-bipass arrangement could be included within the device whereby when connected a portion of the speed reducing drive could be bipassed to facilitate the power withdrawal of the piston, however, such an arrangement would complicate the device and considerably increase its cost. The split nut as herein provided is by far the better arrangement for quick withdrawal of the piston.

The clutch mechanism as shown between members 11 and 15 may be of any other suitable type and located anywhere within the drive train. It is understood that even an electric overload circuit breaker within the motor supply circuitry will suffice, however, with the gear reducing ratio required of the device, binding or damage to the drive train could occur before such a breaker could have time to operate.

While herein is shown one version of the device that has been found satisfactory, it is understood that many variations and modifications may be made therein without departing from the spirit and scope of the invention as shown.

Claims

What I therefore claim and desire to cover by letters patent is:

1. A hand-held caulking gun including in combination a receptacle for receiving a caulking cartridge having a caulking dispensing nozzle thereon, a threaded piston movable when driven through said cartridge to force the caulking within said cartridge from said nozzle, drive means for said piston including a threaded nut disposed about said piston and operative when rotated to drive said piston through said cartridge, a power source, a speed reducing drive train connecting said power source with said nut and operative when actuated by said power source to effect rotation of said nut, fixed means engaging said piston and operative upon rotation of said nut by said power source to prevent rotation of said piston with said nut, and clutch means interposed in said speed reducing drive train between said power source and said nut, and operative to interrupt rotation of said nut upon a predetermined arrested movement of said piston.

2. A caulking gun as claimed in claim 1 wherein the threaded nut is segmented with the segments of said nut being releasably clamped about the threads of said piston in driving relation therewith.

3. A caulking gun as claimed in claim 2 wherein upon release of said segmented nut by said clamping means the segments of said nut may separate from the threads of said piston to allow manual movement of said piston.

4. A caulking gun as claimed in claim 1 wherein said power source is an electric motor.

5. A caulking gun as claimed in claim 2 wherein said segmented nut includes at least three segments.

6. A caulking gun as claimed in claim 5 wherein said segmented nut is conical in configuration and clamped about said piston by being driven into a similarly conical recess included as a part of said speed reducing drive train.

7. A caulking gun as claimed in claim 6 wherein between said conically formed nut and said recess are interlocking drive communicating means.

8. A hand-held electric caulking gun including in combination a receptacle for receiving therein a caulking filled cartridge having thereon a dispensing nozzle, a piston movable when driven through said cartridge to force the caulking within said cartridge from said nozzle, driving means for said piston including an electric motor, a speed reducing drive train connecting said motor with said piston and operable by said motor to effect movement of said piston through said cartridge, and clutch means interposed in said drive train to disengage drivably said motor from said piston upon a predetermined arrested movement of said piston.

9. A caulking gun as claimed in claim 8 wherein movement of said piston is effected by rotation of a nut threadedly engaging a threaded surface upon said piston.

10. A caulking gun as claimed in claim 9 wherein said nut is segmented with the segments of said nut being releasably clamped about the threads upon said piston and operable upon release of said clamping means to threadidly separate from said piston to allow manual movement of said piston.

11. A caulking gun as claimed in claim 8 wherein said drive train includes clutching means operative upon a predetermined arrested movement of said piston to interrupt movement between said electric motor and said piston.

12. A caulking gun as claimed in claim 11 wherein said electric motor is reversible in operation.

13. A caulking gun as claimed in claim 10 wherein said nut is segmented into at least three segments.

14. A hand-held electric caulking gun including in combination a receptacle for receiving a caulking filled cartridge, a piston movable when driven through said cartridge to force the calking from said cartridge, drive means for said piston including a threaded segmented nut, means for releasably clamping the segments of said nut about the threads of said piston, said nut being operative when rotated to effect movement of said piston through said cartridge, an electric motor, a drive train connecting said motor with said nut and operative upon operation of said motor to effect rotation of said nut and clutch means interposed in said drive train and operable upon a predetermined arrested movement of said piston during operation of said motor to stop rotation of said nut.

15. A caulking gun as claimed in claim 14 wherein upon release of said nut clamping means the segments of said nut may separate from the threads of said piston to allow manual movement of said piston through said caulking cartridge.

16. A caulking gun as claimed in claim 14 wherein said segmented nut is conical in configuration and clamped about said piston by being driven by said clamping means into a similarly conical recess included as a part of said driving train.

17. A caulking gun as claimed in claim 16 wherein between said conically formed nut and recess are interlocking drive communicating surfaces.

18. A caulking gun as claimed in claim 14 wherein said electric motor for driving said driving train is reversible.

19. A caulking gun as claimed in claim 14 wherein said segmented nut is comprised of at least three segments.