Spring loaded drive gun

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 06/192,866, filed Mar. 29, 2000.

[0003] The present invention relates generally to drive tools for installing fasteners, and relates more specifically to a drive tool which does not require any upper-body force from an operator to install a fastener.

[0004] Typically (and definitely with regard to self-drilling, self-tapping fasteners), when an operator uses a drive tool, such as a drill, to drive a fastener into a work piece, the operator must use his upper-body strength to apply an axial force to the drive tool. It is advantageous to reduce the amount of upper-body strength an operator must apply to a drive tool to effect the installation of a fastener because doing so reduces the fatigue and physical stress experienced by the operator. This is especially true because oftentimes a large number of fasteners must be installed to complete a job.

[0005] Some drive tools are configured such that, if an operator wishes to use the drive tool to install a fastener into a floor, the operator must get on the floor, on his or her knees, in order to use the drive tool to drive the fastener into the floor. Of course, getting on one's knees every time one installs a fastener in a floor can be uncomfortable and tedious. This is especially true in the case where a large number of fasteners must be installed over a large floor surface area.

[0006] Other drive tools, such as those which are disclosed in U.S. Pat. Nos. 3,960,191; 4,236,555; and 5,897,045 are configured such that an operator can remain standing while using the drive tool to install fasteners into a floor. Such drive tools are essentially extended tools connected to a power drill or to some other driving source. Typically, the drive tool is configured such that fasteners are automatically fed to the end of the drive tool. This provides that the operator can use the drive tool to install a plurality of fasteners without having to bend over each time to place a fastener at the end of the tool. Unfortunately, such drive tools are typically relatively heavy and the operator must apply substantial upper-body effort to apply the necessary axial force to the drive tool to install a fastener. Therefore, using such a drive tool, especially if an operator must use the drive tool everyday for extended periods of time, can be tiring.

[0007] Accordingly, it is an object of an embodiment of the present invention to provide a drive tool which does not require any upper-body force from an operator to install a fastener.

[0008] Another object of an embodiment of the present invention is to provide a drive tool configured such that an operator can easily use his or her own body weight to apply an axial load during a drilling operation.

[0009] Briefly, and in accordance with one or more of the foregoing objects, an embodiment of the present invention provides a drive tool having a top portion which is engageable with a drive source, such as a drill, and a lower portion which is engageable with a fastener. The drive tool includes springs which are configured to urge the lower portion and upper portion of the tool away from each other (i.e. relative movement) and provide that a generally axial force is applied to the fastener engaged with the lower portion of the tool. As a result, the operator does not need to apply any upper-body axial force to the drive tool to install the fastener.

[0010] Preferably, the lower portion of the drive tool includes one or more foot pads on which an operator may stand, and the spring(s) become compressed when the operator stands on the foot pad(s). As a result of the spring(s) trying to expand under compression, a generally axial force is applied to the fastener engaged with the lower portion of the tool, thereby reducing the amount of upper-body axial force an operator must apply to the drive tool to install the fastener. Hence, the operator can use his or her own body weight to apply an axial load during a drilling operation, and need not use any upper-body force.

[0011] The organization and manner of the structure and function of the invention, together with further objects and advantages thereof, may be understood by reference to the following description taken in connection with the accompanying drawings, wherein:

[0012] FIG. 1 is a perspective view of a drive tool in accordance with an embodiment of the present invention, showing (in phantom) a drill engaged with the drive tool;

[0013] FIG. 2 is a front elevational view of the drive tool illustrated in FIG. 1;

[0014] FIG. 3 is a front elevational view similar to FIG. 2, but omitting portions of the drive tool for clarity;

[0015] FIG. 4 is a side elevational view of the drive tool illustrated in FIGS. 1 and 2, showing (in phantom) the drill engaged with the drive tool;

[0016] FIG. 5 is a side elevational view similar to FIG. 4, but omitting portions of the drive tool for clarity;

[0017] FIG. 6 is a top plan view of a foot pad of the drive tool illustrated in FIGS. 1-5;

[0018] FIG. 7 is a cross-sectional view of the drive tool illustrated in FIGS. 1-5, taken along line 7—7 of FIG. 2, showing (in phantom) a drill engaged with the drive tool;

[0019] FIG. 8 is a cross-sectional view of the drive tool illustrated in FIGS. 1-5, taken along line 8—8 of FIG. 2;

[0020] FIG. 9 is a cross-sectional view of the drive tool illustrated in FIGS. 1-5, taken along line 9—9 of FIG. 2;

[0021] FIG. 10 is a cross-sectional view of the drive tool illustrated in FIGS. 1-5, taken along line 10—10 of FIG. 2;

[0022] FIG. 11 is a front elevational view of a drive tool in accordance with another embodiment of the present invention; and

[0023] FIG. 12 is a side elevational view of the drive tool illustrated in FIG. 11, showing (in phantom) a drill engaged with the drive tool.

[0024] While the present invention may be susceptible to embodiment in different forms, there are shown in the drawings, and herein will be described in detail, embodiments of the invention with the understanding that the present description is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to that as illustrated and described herein.

[0025] Shown in the FIGURES are two drive tools 20aand 20beach of which is in accordance an embodiment with the present invention. Specifically, FIGS. 1, 2 and 4 illustrate a drive tool 20ain accordance with a first embodiment of the present invention, and FIGS. 11 and 12 illustrate a drive tool 20bin accordance with a second embodiment of the present invention. Each drive tool 20a, 20bis configured such that an operator can use the drive tool 20a, 20bto drive a fastener into a work piece without having to use a substantial amount of upper-body force.

[0026] The drive tool 20ashown in FIGS. 1, 2 and 4 will be described first, and then the drive tool 20bshown in FIGS. 11 and 12 will be described. In the following description, like reference numerals are used to identify like parts, and different alphabetic suffixes (i.e., “a” and “b”) are used for each of the different embodiments. At times, a detailed description of a part is omitted with the understanding that one may review the description relating to a corresponding part of the other embodiment.

[0027] The drive tool 20ashown in FIGS. 1, 2 and 4 includes an upper end 22awhich is configured for engagement with a drive source 24 (see FIGS. 1, 4 and 7, wherein the drive source 24 is shown in phantom), such as with a power drill, and includes a lower end 26awhich is configured to receive a fastener 28 (see FIG. 10). The drive tool 20aprovides that an operator can engage the drive source 24 with the upper end 22aof the drive tool 20a, and operate the drive source 24 to cause the drive tool 20ato drive the fastener 28 into a work piece, without the operator having to use a substantial amount of upper-body force.

[0028] As shown in FIGS. 1-5 and 10, the drive tool 20apreferably includes a foot pad 30aon which the operator can stand when operating the drive tool 20a(the foot pad 30ais shown generally isolated in FIG. 6). As a result, the operator can use his or her own body weight to apply an axial load to the fastener 28 while using the drive tool 20ato drive the fastener 28 into a work piece.

[0029] Preferably, the foot pad 30aextends from a bracket 32awhich is attached to the lower end 26aof the drive tool 20a, and the foot pad 30ais pivotable about an axis 34a(see FIG. 1). Preferably, the foot pad 30ais pivotable such that when an operator stands on the foot pad 30a, an outer edge 36aof the foot pad 30apivots downward (i.e., the foot pad 30apivots about axis 34a) and contacts the floor. Incidentally, the other edge 38aof the foot pad 30adrops down close to the floor, but preferably does not touch the floor. This arrangement of having the axis 34adown by the end 42aof the tool 20a, allows the tool 20ato have a fulcrum point close to the floor. This results in the tool 20ahaving, effectively, a maximum amount of freedom to pivot in any direction. Pivoting is important to allow the operator to accommodate an uneven floor surface or other obstruction. In addition, the foot pad 30aprovides that an operator can place both feet on the foot pad 30a, thereby maintaining his or her balance, and allows the operator to step one foot at a time on the foot pad 30a.

[0030] The foot pad 30amay also be configured such that the foot pad 30acan be pivoted upward into a non-operating position, and can be pivoted downward into an operating position (which is shown in the FIGURES). As will be described more fully later herein, preferably the foot pad 30ais spring-connected to a higher portion of the drive tool 20aso that the foot pad 30adoes not tend to drop down between installations.

[0031] Although not shown, the drive tool 20amay include handles extending outwardly from the upper end 22aof the drive tool 20a.The handles would allow an operator to readily grip the drive tool 20aduring use. The handles would also facilitate transportation of the drive tool 20a, such as the transportation of the drive tool 20aat a given job site, as well as the transportation of the drive tool 20afrom one job site to another.

[0032] Preferably, as shown in FIGS. 1, 2, 4 and 7-10, an automatic fastener feeding mechanism 40ais in communication with the lower end 26aof the drive tool 20a. The automatic fastener feeding mechanism 40ais preferably configured to automatically feed fasteners 28 to the end 42aof the drive tool 20aso that an operator need not bend over and engage a fastener with the end 42aof the drive tool 20aeach time the drive tool 20ais to be used to drive a fastener 28 into a work piece.

[0033] As shown, the automatic fastener feeding mechanism 40amay comprise a gravity feed tube 44athat includes a funnel end piece 46ato facilitate the deposit of fasteners 28 into the feed tube 44a. As such, the feed tube 44aessentially functions as a conduit between the standing operator and the end 42aof the drive tool 20a. Alternatively, the automatic fastener feeding mechanism 40amay comprise a magazine feed tube or a cartridge feeder.

[0034] As shown in FIGS. 1, 2, 4 and 7, the upper end 22aof the drive tool 20aincludes a housing 48a. The housing 48aincludes an opening 50aat an end 52athereof for receiving the drive source 24 (see FIGS. 1, 4 and 7), such as for receiving the driven, rotating portion of a power drill. The housing 48amay include an upper portion 54awhich provides the opening 50a, and a lower portion 56ato which the upper portion 54ais secured (said securement including adjustable clamp 58a—see FIGS. 1, 2 and 4). Alternatively, the housing 48acan be provided as a single piece, effectively incorporating upper portion 54aand lower portion 56a.

[0035] As shown in FIGS. 1, 2, 4 and 7, the lower portion 56aof the housing 48ais attached to an upper tube 60a(via securing members 62aand adjustable clamp 64a), and the upper tube 60aincludes a slot 66a(see FIGS. 1 and 8). As shown in FIG. 7, a collar 68ais secured to the lower portion 56aof the housing 48a(via securing members 62a) and engages an end 70aof a spring 72adisposed in the upper tube 60a. As shown in FIG. 8, collar and guide structure 74ais preferably disposed on the collar 68a, and the spring 72aextends through the upper tube 60aand engages a top surface 76aof a lower tube 80a. Specifically, 74A in FIG. 8 points to two different components. The upper component is a collar that is pressed onto the shaft 114a, and does not move. The lower component is a “guide” that slides along the shaft 114abut has threads on its outside diameter and is threaded onto the collar 68a. The spring 72aserves to return the drive tool 20ato its starting position in use.

[0036] As shown in FIGS. 1, 4 and 7, a stop bracket 82ais attached to the feed tube 44a(via wing nut 84a), and is secured to the lower tube 80aand a bottom tube cap 86a(via securing members 88a). Preferably, as shown in FIGS. 1 and 4, the feed tube 44ais also connected to the lower tube 80avia an adjustable bracket 90a. The adjustable bracket 90amay provide that the length of travel of the drive tool 20a(during operation) can be adjusted. Alternatively, a torque clutch (i.e., a slip clutch) can be provided.

[0037] As shown in FIGS. 1, 2, 4 and 10, the lower tube 80aextends from an opening 92ain the bottom end 94aof the upper tube 60asuch that the lower tube 80aessentially telescopes from the opening 92a. Specifically, the lower tube 80aextends from the opening 92ain the upper tube 60aand is moveable relative to the upper tube 60aduring a drilling operation. This will be described more fully herein.

[0038] As shown in FIG. 10, the foot pad bracket 32ais secured to the bottom of the lower tube 80avia securing member 96aand button head screw 98a. As shown in FIGS. 1, 4 and 10, a shuttle 100aeffectively connects the lower end of the gravity feed tube 44ato the lower tube 80a. Preferably, the button head screw 98aconnects to a nosepiece or end piece 104a, and provides that the end piece 104acan be relatively easily removed from the lower tube 80aand replaced. The end piece 104aultimately receives the fasteners from the feed tube 44a(see FIG. 10), and the fasteners 28 exit an opening 106ain the end 42aof the end piece 104awhen they are installed using the drive tool 20a. As shown (see, for example, FIGS. 1, 2 and 4), preferably the opening 106aincludes four slots 108awhich allow “chip relief” (i.e., allow chips to escape from under the drill tool 20aduring drilling).

[0039] As discussed above, the housing 48aat the top of the drive tool 20ahas an opening 50aconfigured for receiving a drive source 24, such as the rotating, driven end of a power drill. As shown in FIG. 7, the drive source 24 engages an adaptor 112ain the housing 48a, and the adaptor 112aengages a shaft 114athat extends along a substantial length of the drive tool 20a. The shaft 114aextends from the adaptor 112a, through the collar 68a, through the spring 72a, through the bottom tube cap 86a, and is engaged, at its end, with an extension 116a. As shown in FIGS. 9 and 10, the extension 116aengages a drive bit 164aor nut driver in the end piece 104a, and the drive bit 164aengages the fastener 28 to be installed using the drive tool 20a. Preferably, a retaining ring 166aand ball bearing 168aretain the drive bit 164awith the end of the shaft 114a. A pair of set screws may also be provided to retain the drive bit 164ato the end of the shaft 114a. Preferably, the engagement is such that the drive 164abit can be easily replaced. Although the shaft 114ais shown engaged with an extension 116a, the extension 116acould be omitted, in such case the shaft 114awould be longer than depicted in the FIGURES and would engage directly with the drive bit 164a.

[0040] As shown in FIG. 10, the shuttle 100aprovides a passageway 170aextending between the gravity feed tube 44aand the end piece 104a, and the passageway 170aprovides that a fastener 28 can travel from the gravity feed tube 44ato the end piece 104a. Preferably, a fastener retaining structure 172ais provided in the end piece 104afor engagement with the fastener 28 when the fastener 28 is disposed in the end piece 104a. Specifically, the fastener retaining structure 172amay comprise an o-ring 174aand steel ball 176a. Preferably, the fastener retaining structure 172aallows any unwanted fasteners in the end piece 104ato be easily removed.

[0041] As shown in FIGS. 1, 3, 4, 5, 9 and 10, the foot pad 30ais preferably spring-connected to the upper tube 60a. Specifically, preferably a ring 180ais connected to the foot pad 30a, and the ring 180aengaged with a removable ring 182athat is engaged with a spring 184a(the spring 184ais represented by a dashed line in FIGS. 3 and 6). The opposite end of the spring 184ais engaged with another removable ring 186athat is engaged with a ring 188athat is secured to an upper bracket 190aon the upper tube 60a. The upper bracket 190ais threaded to the upper tube 60aand is further retained thereon by a set screw 191a. Additionally, nut 192aeffectively retains the upper bracket 190aon the upper tube 60a. The fact that the foot pad 30ais spring-connected to the bracket 190aserves the purpose of generally preventing the foot pad 30afrom simply dropping down when the drill tool 20ais lifted as it is positioned for the next fastener. Otherwise, the drive tool 20awould be relatively difficult to maneuver between fastenings.

[0042] As shown in FIGS. 1 and 2, a lower bracket 194ais secured to the lower tube 80a, and a pair of rods 200a—one on each side of the drive tool 20a—are attached to the lower bracket 194a. The rods 200aare generally parallel to the upper and lower tubes, 60aand 80a, and extend upward, and through the upper bracket 190ato which the spring 184ais effectively attached. Preferably, each of the rods 200ais threaded or at least includes a threaded portion such that a nut 202aand washer 204aare engaged with each rod 200a. As shown in FIGS. 1-5, each rod 200acarries a spring 210a, and each spring 210ais disposed between the upper bracket 190aand the washer 204aon the rod 200a. Preferably, the nuts 202acan be adjusted along the lengths of the rods 200a, and this provides that the initial compression of the springs 210acan be adjusted.

[0043] Because the rods 200aare effectively attached to the lower tube 80a(via lower bracket 194a), when an operator places the end piece 104aof the drive tool 20aonto the floor and steps on the foot pad 30a, his or her body weight forces the rods 200ato travel downward. As the rods 200atravel downward, the washers 204acompress the springs 210a, and the springs 210aexert a force against the upper bracket 190a. Since the upper bracket 190ais secured to the upper tube 60a, this compression pushes the upper tube 60adownward and applies an end load to the fastener. Hence, an operator can install a fastener using his or her body weight (by applying same to the foot pad 30a) without having to employ a substantial amount of upper-body axial force.

[0044] Typically, a fastener will require a given end load in order to successfully drill through and form threads. Preferably, the load/deflection design of the springs 210ais such that the springs 210aexert the required amount of load generally uniformly throughout the length of travel needed for the drilling sequence. The springs 210athen preferably maintain sufficient load (albeit preferably somewhat less) after the drilling sequence to allow the thread forming sequence to occur.

[0045] Preferably, the drive tool 20ais configured such that the length of travel, during operation, of the drive tool 20ais adjustable to accommodate different length screws. This can be performed by changing the position of screws 212a(see, for example, FIG. 3) that go into the bracket 90asecured to the feed tube 44a. Preferably, the adjustment can be made in 0.5 inch increments. Additional fine tuning can be effected by turning nut 192ato which the upper bracket 190ais affixed. This additional fine tuning is needed in case it is required to manually disengage the socket from the head of the fastener.

[0046] To use the drive tool 20ato drive a fastener 28 into a work piece, an operator engages a drive source 24 with the end 52aof the housing 48a. Then, the operator drops one or more fasteners 28 into the gravity feed tube 44a. Preferably, the operator drops a fastener 28 having a flange thereon 220 as shown in FIG. 10. Specifically, the fastener 28 may be a self-drilling fastener, such as a fastener consistent with that which is shown and described in U.S. Pat. No. 5,605,423, which is incorporated herein in its entirety by reference.

[0047] The fastener 28 moves from the gravity feed tube 44a, through the passageway 170ain the shuttle 100a, and into the end piece 104a, to the position shown in FIG. 10. As shown, preferably the fastener 28 drops into a position such that the lower flange 220 on the fastener 28 contacts the steel ball 176ain the end piece 104a. The steel ball 176aprevents the fastener 28 from exiting prematurely from the opening 106aof the end piece 104a, and positions the fastener for engagement by the socket and prevents the fastener from sticking out of the nosepiece prematurely.

[0048] Thereafter, the operator manipulates the drive tool 20asuch that the end of the fastener 28 is disposed against the work piece, at the location at which the operator wants to install the fastener 28. Then, the operator steps on the foot pad 30aand operates the drive source 24 to cause the adaptor 112a, shaft 114aand drive bit 164ato rotate. When the operator stands on the foot pad 30a, the outer edge 36aof the foot pad 30apivots downward (i.e., the foot pad 30apivots about axis 34a) and contacts the floor. The other edge 38aof the foot pad 30apreferably drops down close to the floor, but preferably does not touch the floor. Because the rods 200aare effectively attached to the lower tube 80a(via lower bracket 194a), when an operator places the end piece 104aof the drive tool 20aonto the floor and steps on the foot pad 30a, his or her body weight forces the rods 200ato travel downward. As the rods 200atravel downward, the washers 204acompress the springs 210a, and the springs 210aexert a force against the upper bracket 190a. Since the upper bracket 190ais secured to the upper tube 60a, this compression pushes the upper tube 60adownward and the upper tube 60atelescopes downwardly over the lower tube 80a. The combination of the spring-loaded force and the operator force on the foot pad 30aof the drive tool 20acauses the drive tool 20ato apply an end load to the fastener, thereby forcing the fastener 28 beyond the steel ball 176ain the end piece 104a, and driving the fastener 28 into the work piece. Hence, an operator can use the drive tool 20ato install a fastener using his or her body weight (on the foot pad 30a), without having to employ a substantial amount of upper-body axial force.

[0049] While the fastener 28 is being driven into the work piece, the compression of the springs 210aimparts an axially directed force along the shaft 114a. Hence, the structure provides an axial load assist mechanism that effectively reduces the amount of upper-body axial force an operator must apply to the drive tool 20a. Hence, the operator can use the drive tool 20ato install fasteners more quickly and with less effort. Preferably, the springs 210acreate a generally constant axial spring load throughout the drilling and thread forming process. Additionally, during drilling and tapping, preferably a constant force is kept on the fastener. Preferably, the springs 210aapply a constant axial load resulting in fast drill and tapping times.

[0050] Once the fastener has been driven into the work piece, the operator can step off the foot pad 30aand the drive tool 20awill return to the starting position (due to the force of the spring 72a). At this point, another fastener 28 is fed to the end piece 104afrom the gravity feed tube 44a.

[0051] The drive tool 20bshown in FIGS. 11-12 is similar to the drive tool 20ashown in FIGS. 1, 2 and 4, and hence, like drive tool 20a, includes, among other parts, a foot pad 30b, an automatic fastener feeding mechanism 40b, a housing 48b, an upper tube 60b, a lower tube 80b, a shuttle 100b, an end piece 104band a spring 184b. In fact, the only major difference between the drive tool 20bshown in FIGS. 10-12 and the drive tool 20ashown in FIGS. 1, 2 and 4 is that instead of including springs on rods on each side of the drive tool, as is provided on drive tool 20a, the drive tool 20bshown in FIGS. 11-12 includes a single spring 240bwhich is retained on the lower tube 80b, between a ring 242band an adjustable nut 244b. Ring 242bis adjustable up or down, and serves as a stop for the spring 240b. Operation of the drive tool 20bis effectively the same as operation of the drive tool 20aalready described except that when an operator steps on the foot pad 30b, the single spring 240bcompresses between the ring 242band nut 244bto provide an axial assist mechanism that obviates the need for the operator to employ a substantial amount of upper-body force to effect a drilling operation. As shown, the drive tool 20bdoes include rods 200bon each side of the drive tool 20b, but, unlike the rods 200aof drive tool 20a, do not carry springs which compress when an operator steps on the foot pad 30b.

[0052] Although not shown in the FIGURES, either one of the drive tools 20a, 20bcan be provided with wheels for facilitating the transportation of the tool—both between fastenings at a given site and from one site to another.

[0053] While embodiments of the present invention are shown and described, it is envisioned that those skilled in the art may devise various modifications without departing from the spirit and scope of the appended claims.