PNEUMATICALLY CONTROLLED MECHANIZED APPLICATOR FOR DRYWALL MASTIC AND TAPE

Abstract: An automatic, powerized system delivers mastic and tape to a drywall during an installation thereof. In a delivery head (42) on the end of a wand (32), a plurality of pneumatic cylinders control the delivery of mastic and tape responsive to finger tip controls (34) on the wand. The entire system may be cleaned out by substituting a source of running water for a source of mastic.

Description: PNEUMATICALLY CONTROLLED MECHANIZED APPLICATOR FOR DRYWALL MASTIC AND TAPE This invention relates to tools for use during the installation or repair of wallboard or drywall and more particularly to pneumatically controlled, large volume, mechanized applicators for filling recesses in the wallboard or drywall with a mastic and for applying tape during the application of the mastic. The inventive tool is related to tools such as that shown and described in U.S. Patent 4,105,490. During the erection and installation of wallboard or drywall, there are many reasons why joints, holes, and other irregularities appear on the surface of a wallboard panel. For example, these panels are usually four feet wide, are installed in an edge to edge abutment, and held in place by nails or screws, which are set into the wallboard so that the nail or screw heads will not show on the finished wall. This form of installation leaves cracks, small holes, and sometimes, nicks or gouges. Regardless of how they got there, all such surface discontinuities must be filled with a suitable mastic (sometimes called "mud") to give a smooth plaster-like surface. If there are cracks or if the discontinuities are large enough, tape must be embedded in the mastic to give a greater degree of mechanical strength. Finishing drywall or wallboard surfaces under these conditions is basically a multi-step process, with a drying phase between each step. A bedding coat of joint compound or other mastic ills a crack or recess formed in the wallboard which may or may not be reinforced with a tape, depending upon the needs and the size of the crack or recess. After the mastic or compound is applied and while it is still set, excess compound should be wiped down. Compound or mastic shrinks as it dries, which results in slight depressions that are illed by * applying one or more topping or finishing coats of the mastic or compound. Regardless of how the tools for applying the mastic are used, it is necessary to load, unload, and clean them. A conventional hand tool has a box-like open area into which the mastic or compound is first loaded and then squeezed out and onto the wall. The tool must be filled and cleaned often. Some of the mastic dries relatively" fast so that, if it is not cleaned promptly, small hard bits will collect in and on the tool to prevent a smooth uniformity in the deposited material. Sometimes the drying mastic material may interfere with, obstruct, or perhaps even immobilize tool parts. Thus, it becomes necessary and desirable to reduce the time required to clean the tool and to eliminate nooks, crannies, and other configurations within the tool which may tend to collect debris that cannot be adequately cleaned. Another problem is that it has heretofore been necessary to cut tape to size, and fit it into the crack, as it is embedded in the mastic. Accordingly, there is a need for a large volume tool which does not have to be cleaned and refilled as often as was heretofore required. There is also a need for dispensing tape along with the mastic- Accordingly, an object of the invention is to provide new and improved tools for applying both tape and mastic and other compositions to wallboards or drywalls. In particularly, an object is to provide a large volume tool for applying mastic which eliminates much of the need for repeatedly cleaning the mastic from the tool. Here, an object is to provide a user friendly tool which requires no special training and which requires little maintenance and no user maintenance. Still another object is to provide a tool for applying and cutting off the tape, as it is required. Yet another object is to provide a power assisted tool for simultaneously applying tape and mastic. A further object of the invention is to provide a tool which is easy to guide or steer as it is moved over the wall, with lower operator fatigue. In keeping with an aspect of the invention, these and other objects are accomplished by a tool which has a large reservoir containing a mastic or composition which is fed through a hand held wand to the point of application on the drywall. Tape is also fed via the wand to the wall where it is embedded in the mastic as it is applied. All of these functions are controlled from finger tip controls which operate pneumatic cylinders that control the various functions. A preferred embodiment of the invention is shown in the attached drawings, wherein: Fig. 1 illustrates the inventive tool; Fig. 1A is an exploded view of a control head also shown in Fig. 1; Fig. 2 is an exploded view of the mastic applicator and tape applying head; Fig. 3 is a cross-section of a side elevation of the inventive tool showing how the parts of Fig. 2 are interconnected. The inventive machine (Fig. 1) includes a wheeled cart 20 having mounted thereon an electric air compressor, a hopper or reservoir 24 for mastic, and a reel 26 for receiving and paying out a hose. A wand 32 is connected between the mastic or mud hose 28/air line 30 combination and a mastic and tape applying head 42. The conduit 28 supplies the mastic and air line 30 supplies pressurized air for powering air cylinders in the head. Suitable finger tip controls are provided at control head 34. These controls (Fig. 1A) may be any suitable devices, such as plastic covered push buttons PBl, PB2, for example. Push button PBl operates a tape cutter in head 42. Push button PB2 controls the flow of mastic to the head 42. The collar 35 attaches to control head 34 in order to provide mechanical protection for the push buttons. A roll or magazine of tape 36 is mounted on the wand at a suitable location which places the center of gravity in an easy to manipulate position. The tap 38 is fed through head 42 responsive to an operation of a suitable control lever 40. At the top of the wand, head 42 includes a body 44 for advancing and delivering both the tape and the mastic to the wall. A tape advance mechanism includes a wheel 48 which rolls along the wall to support the tool, and a creaser 50 for pressing the tape into a desired position. A cutter block 52 cuts off the tape after it has been applied. An exploded view of the taping and mastic delivery head 42 is shown in Fig. 2. An assembled view of the same head is seen in Fig. 3. The various parts are supported in a housing formed from a cover plate 60 and two side plates 62, 64 which are joined by being bolted to two sets of cover supports bars 66, 68. These cover and side plates have a number of holes or openings formed therein to receive bolts, screws, rivets, etc. most of which are not shown, in order to avoid a cluttered drawing. A transition mount 70 is fastened to the rear edges of the cover and side plates 60-64 in order to provide a transition between the rectangular cross-section of the housing and the circular cross-section of the wand 32. A bracket 72 spreads and secures the lower opposed corners of side plates 62, 64 while securing the bottom of transition mount 70. The nozzle 74 for dispensing the mastic has a nozzle outlet or control valve 76 and a mastic inlet 78. Valve 76 sets in outlet 79. The flow of the mastic is responsive to valve 76, which in turn is controlled by components enclosed by a cover plate 110 attached to the outside of side plate 62. The components selectively rotate,the nozzle inlet valve 76 responsive to the operator's finger tip control, thus making it act as a stop-cock valve. The control structure comprises a valve actuator lever 112 mounted on a bearing 114 integrally formed on a shoulder screw 116. A driving gear 118 and a driven gear 120 are turned as the lever arm 112 rotates under an urging of an air or pneumatic cylinder 122 which is coupled to arm 112 via shaft 124, which is attached to an outer end of arm 112 by a bolt 126. The shaft 124 passes through an arcuate slot 128 in the side plate 62 so that it is free to move with and as air cylinder 122 extends or retracts. Thus, responsive to a finger tip control 34 (Fig. 1) , as air cylinder 122 extends its arm, shaft 124 moves arm 112 in one direction to rotate wheel 118 in one direction. This turns gear 120 and the mastic flow control stop-cock valve 76 to one position. When air cylinder 122 retracts its arm, the process is opposite in order to rotate the valve 76 to an opposite position. This opens and closes the mastic flow control valve 76 depending upon the position of the air cylinder arm. Two o-rings 130 seal the openings 131 at the ends of valve 76 to prevent an escape of the mastic from the nozzle 74 into the interior of head 42. The tape control and advance mechanism begins with two rubber pinch rollers 132, 134 mounted on hub units 136, 138, respectively. Hub 136 is mounted on shaft 140 while hub 138 is mounted on shaft 142. These shafts and hubs are rotatably supported by suitable bearings and related equipment. The tape passes between pinch rollers 132, 134 and through tape guides 148, 150 which have two confronting guide slots 152, 154 for the tape to pass through. The tape issuing from slots 152, 154 passes through a slot 156 in an inlet block of metal. A guillotine cutter blade 160 is mounted on a cutter blade holder 162 having a pair of upstanding ears 164, 166 which are coupled to a cutter actuator arm 168 by a pin 170. The actuator arm 168 is controlled by a pneumatic or air cylinder 175 which is secured in place by a pair of brackets 172, 174. An anvil 176 is positioned to shear the tape when the guillotine cutter blade 160 moves up and then down. A leaf spring 178 keeps the pressure upon the anvil which insures the shearing action by a movement of the blade 160. Normally, the air cylinder 175 holds the cutter blade 160 in an elevated position. When a finger tip push button is pressed at 34 (Fig. 1) , the air or pneumatic cylinder 175 moves actuator arm 168 which, in turn, lowers blade 160 and cuts the tape. Thereafter cylinder 175 returns the blade to its starting position. The cutter assembly is completed by a cover 171 and base 173. Plate 175 is a tape guide. Two rollers 177, 179 assist in guiding the tape. The control an advance of the tap 38 (Fig. 1) , a rack and pinion 184 (Fig. 2) is actuated by an air or pneumatic cylinder 186 responsive to control lever 40 (Fig. 1). Two hubs 188, 190 are supported on a tape wheel shaft 192 which also receives a creaser arm 194 carrying a creaser wheel 196 that is especially useful when tape is applied to an inside corner of the drywall. The movement of creaser arm 94 is controlled by a creaser cable 198 and return spring 200. As the creaser arm and wheel press the center of the tape while it is being applied to the wall, spring 173 provides enough give to apply a predetermined amount of pressure to the tape. Outside of the hubs 188, 190 are two tape wheels 202, 204 which press the edges of the tape into place. Two tape wheel hub assemblies 206, 208 hold the wheels in place on shaft 192. The operation of the tool should now be apparent. The compressor 22 (Fig. 1) is started and pressurized mastic is forced through hose 28 and wand 32. At the push of a finger tip push button at 34, air cylinder 122 operates to rotate mastic flow control valve 76, and thereby enable mastic to flow out of outlet 79 and on the wall. The tape is deposited on the drywall and is embedded in the mastic as rack and pinion 184 respond to air cylinder 186. As air cylinder 186 operates rack and pinion 184, the pinch roller wheels 132, 134 rotate and deliver the tape from their nip toward the wall. The worker moves wand 32 to distribute the mastic and tape over the wall in order to fill a crack, for example. When the worker reaches an. end of a crack, he pushes a suitable push button (not shown) at 34 (Fig. 1) . Air cylinder 122 rotates valve 76 to cut off the flow of mastic. At the same time, air cylinder 175 moves the guillotine cutter blade 160 to shear the tape. This tool provides many advantages over other tools which have been known in the past. 1. There are longer operating times between loadings. The tool system holds up to ten gallons of joint compound in its hopper/pump combination cart. 2. There is lower operator fatigue. The taper is lighter in weight. Its controls are finger- operated air valves requiring little effort. 3. All mechanical functions (tape advance, tape cutting, and compound flow control) are carried out by an operation of the air cylinders. 4. There are no user-replaceable parts. Tape cutting and advance mechanisms are factory set and maintained. 5. No special training is required on behalf of the operators. They need only to learn the location of the controls. 6. Maintenance by the user is limited to connecting the tool to a water hose and flushing out the system at the end of the day. Those who are skilled in the art will readily perceive how to modify the invention.. Therefore, the appended claims are to be construed to cover all equivalent structures which fall within the true scope and spirit of the invention.

Claims: WHAT IS CLAIMED IS; 1. A large-volume, pneumatically-controlled drywall mastic and tape applicator comprising a wand having a taping and mastic delivery head, means attached at one end, power driven means in said head for substantially simultaneously applying tape and mastic to a point of application on wallboard or drywall surfaces, and finger tip operated means on said wand for pneumatically controlling the power driven means in the delivery head of said applicator. 2. The applicator of claim 2, and means for delivering said mastic under pressure to said taping and mastic delivery head, a nozzle valve for controlling a flow of said pressurized mastic out of said head, and means responsive to a pneumatic cylinder for controlling the operation of said valve to regulate the flow of the mastic. 3. The applicator of claim 1, and a tape control and advance mechanism in the taping and mastic delivery head, a pair of pinch rollers for delivering the tape into a desired position, a pneumatic cylinder for turning said pinch rollers in order to deliver said tape from said head, and cutter means for cutting the tape once it has been applied to the wallboard or drywall surfaces. 4. The applicator of claim 3, wherein said pinch roller comprises a pair of rubber rollers mounted on hub units with said tape passing through a nip between said pinch rollers, and said tape control and advance mechanism comprises a rack and pinion driven by a pneumatic cylinder for turning said pinch rollers and controlling the advance of the tape. 5. The applicator of claim 3, wherein said delivery head further comprises a creaser wheel mounted on a spring biased arm for pressing said tape into a corner, and tape wheels for pressing the edges of the tape into place on said wall. 6. The applicator of claim 3, wherein said cutter means comprises a guillotine cutter blade, a cutter controlling pneumatic cylinder, and means responsive to said cutter controlling pneumatic cylinder for controlling the upward and downward movement of said guillotine cutter blade. 7. The applicator of claims 1-6 wherein the pneumatic controlling means comprise a plurality of pneumatic cylinders for individually controlling the functions of said applicator in response to said finger tip controls on said wand. 8. The applicator of claim 1, further comprising a hose consisting of a conduit for pressurized mastic and an air line for supplying pressurizing air for powering a plurality of pneumatic cylinders in said delivery head, said conduit and air line being connected to an opposite end of said wand which is opposite to the end onto which said delivery head is connected. 9. The applicator of claim 8 and a stop-cock valve, one of said pneumatic cylinders being a part of means for controlling a rotation of said stop-cock valve to regulate a flow of the mastic onto the wall. 10. The applicator of claim 8, and a pair of pinch wheels, a rack and pinion coupled to rotate said pinch wheels and control the advance of the tape, one of said pneumatic cylinders being part of means for actuating said rack and pinion. 11. The applicator of claim 8, and a guillotine cutter, one of said pneumatic cylinders being part of a control means for effectuating upward and downward movements of said guillotine cutter blade for cutting said tape. 12. A drywall installation tool system comprising supply means for supplying a large volume of drywall mastic and pressurized air, a wand having a tape and mastic delivery head attached to one end thereof, means for conveying said pressurized mastic and air from said supply means to said delivery head via said wand, a supply of tape mounted on said wand for delivery to said delivery head, a plurality of air cylinders in said head for controlling a flow of mastic and a delivery of tape to a drywall, and control means on said wand for individually controlling said air cylinders. 13. The drywall tool of claim 12 further comprising: a valve means in said head for controlling the flow of mastic to said wall, a rack and pinion set of pinch rollers for delivering said tape, and a guillotine cutter for cutting said tape; said plurality of air cylinders being individually associated with said valve means, said rack and pinion, and said cutters; and means on said wand for individually controlling said air cylinders. 14. The drywall tool of claim 13 and means for disconnecting said drywall mastic supply means from said wand and for connecting a source of pressurized water in place of said mastic supply means whereby said wand and delivery head may be cleaned out by running water from said pressurized water source through said wand and delivery head.

Inventors: SAGASTEGUI JAVIER, SAGASTEGUI, JAVIER
Applicants: AXIA INC, AXIA INCORPORATED
Application year: 1992
Main classification: B44C3
IPC codes: B44C7, E04F21