Patent Application
20140103089
This invention relates to fastening tools and has particular application for fastening floorboards to a subfloor.
Floorboards for hardwood floors are generally milled as lengths of several feet and widths of a few inches. Typically the boards are from a half to one inch in thickness with one edge formed with a tongue and the other edge formed with a matching groove. The boards are laid edge to edge with the tongue of one board inserted into the groove of the next adjacent board. The boards are laid successively from one wall of the room being covered. For a neat appearance and to avoid the presence of grooves between adjacent boards where detritus can gather, a board being nailed is pressed tightly against the previously laid board before it is fastened.
Generally boards are fastened using nails or staples so that the fastener is not visible in the finished floor. One way of doing this is to drive the fastener diagonally into the side of the board so that the fastener penetrates the edge of the board at an entry position spaced from the top face of the board. The fastener is driven through a lower part of the board, exits the bottom face of the board and enters the subfloor. The fastener is driven some way into the subfloor and the frictional grip between the leading part of the nail or staple and the subfloor material such as plywood retains the fastened board in position against the subfloor and against its neighbouring board. The boards are laid in sequence so that the grooved edges face the starting wall and fasteners are driven through the tongued edges. The fastener is driven into the tongued edge at 45 degrees to the vertical at the corner junction between the top edge portion of the board and the top face of the tongue. In this way, the fastener does not protrude in such a way as might adversely affect the fitting of the next board to be fastened against the board previously fastened. The successive fastening in this way means that an essentially integral floor structure is obtained with each fastening of a board contributing through the tightly interlocking of the tongue and groove arrangement to the clamping in place of its neighbouring boards.
The angled drive applied to a fastener has two mechanical effects. Firstly, the horizontal component of the applied angled drive presses a board to be fastened laterally against the previously laid board so that the respective tongue and groove are locked and the adjacent edges of the two boards are pressed tightly together. Secondly, the vertical component of the applied angled drive presses the board being fastened firmly against the subfloor so that there is no gap between the board and the subfloor after the fastening operation is complete. The two mechanical effects overlap during the driving operation so that the lateral pressure is applied to the board as it is fixed to the subfloor.
A conventional fastening tool has a cartridge of fasteners such as staples or nails, a multiple charge of fasteners being spring mounted in the cartridge so as to bias a leading fastener into a position ready for its being driven. The tool has a rebated shoe which is used to locate the tool next to a board in the proper position for executing a fastening operation. The rebate is dimensioned so that its top face sits on top of the board to be fastened, its vertical face fits against the tongued end of that board, and an adjacent heel section of the shoe rests on the subfloor. The shoe has a launch aperture through which the readied fastener is driven in an operation as previously described. Once the fastener is driven into the board, the next adjacent fastener in the cartridge is spring biased into the ready position and the tool is lifted away from the board and located against another section of the board edge in preparation for driving another fastener.
In order that the fastener is effectively driven through the board and into the subfloor, a drive must be applied longitudinally to the fastener; i.e. along the line of the shank in the case of a nail and along the line of the two penetrating spikes in the case of the staple which is generally of the form of an inverted U. The drive applied is a percussive drive rather than the application of a high, non-percussive force. This, in turn, means that a hammer element such as a hammer head or a piston must gain momentum before it strikes the readied fastener to drive it through an edge portion of a board and into the subfloor. In a mechanical version of the flooring tool, a piston is spring mounted for reciprocation in a tool barrel. The piston has a leading edge adapted to strike the readied fastener and a strike head at the other end of the piston which is hammered to effect piston movement against the spring mounting to drive the leading edge against the fastener. In the case where such a tool uses an adjunct power source, there is usually a two-phase drive. Typically, such an adjunct power source is compressed air, although power sources, such as electromagnetism, flammable expanding gases (e.g. propane), or a small explosive charge may alternatively be used. It is understood that although compressed air is the favoured and effectively the most used fluid for fastener driving tools, other suitable compressible fluids or other power adjuncts could be used without departing from the scope of the present invention. For a compressed air powered driving tool, a top piston is first hammered against a spring bias to initiate drive of the top piston along a barrel. At a certain distance along its travel, the top piston clears an aperture in a wall of the barrel allowing fluid communication with a source of compressed air. Compressed air is then injected into the barrel to force a bottom piston against the readied fastener.
One issue with known board fastening tools is that a finite travel of the piston (or pistons in the case of the compressed air tool) in the barrel is needed to generate the required momentum for the fastener to be driven into the board and subfloor from its readied position. In addition, a swing of the hammer is required that further lengthens the drive room needed. Because swinging the hammer and driving the piston along the inclined barrel occur in the direction that the boards are being laid—i.e. away from the starting wall—this means that as illustrated by
According to one aspect of the invention, there is provided a board fastening tool comprising a tool body and a driver, the driver having a percussion head drivable in a first direction upon receiving a first percussion drive from a hammer member, a fastener head to apply a second percussion drive in a second direction to a fastener lodged in a strike position in the fastening tool, and a transmission element between the percussion head and the fastener head for transforming the first percussion drive into the second percussion drive.
Preferably, the transmission element includes an elongate flexible member mounted in and reciprocably movable along a curved track, the elongate flexible member conformable to the curvature of the track on movement of the elongate member along the track. The elongate flexible member can be a spring steel member elastically conformable to the curvature of the track upon movement of the spring steel member along the track.
The curved track is preferably contiguous with a first passage, the fastener head mounted for reciprocal, linear movement along the first passage, with the fastener head being reciprocally movable along the first passage on an axis inclined at an angle between 30 and 60 degrees to the horizontal when the fastening tool is in an operational position.
The curved portion of the track can be contiguous with a second passage, the percussion head including an elongate driver member mounted for reciprocal, linear movement along the second passage, with the second passage extending generally vertically when the board fastening tool is in an operational position.
For use with a fastener having a contact end, the board fastening tool, the fastener head have a leading tip with a shape generally matching the shape of the fastener contact end.
The board fastening tool can further comprise an adjunct power unit operable in response to the first percussion drive to apply power for the second percussion drive. The percussion head can include a reciprocally drivable anvil for receiving the percussion drive from the hammer member, the anvil linked to a power actuator for triggering generation of a power pulse from the adjunct power unit to drive the elongate driver member along the second passage upon downward movement of the anvil. The power source can be any convenient adjunct power but is preferably compressed air.
The elongate flexible member can be constrained to move along the curved track by a track wall confining the elongate member to a preset curvature. The elongate flexible member can include a plurality of elements, adjacent elements linked to each other along the length of the flexible member by a respective articulated linkage. Alternatively, elongate flexible member is a longitudinally incompressible cable.
The transmission element can include a rotatable member rotatable about an axis, the rotatable member having a first contact element drivable by the percussion head on movement of the percussion head in the first direction to turn the rotatable member about the axis, and a second contact element forming a part of the rotatable member for driving the fastener head in the second direction upon turning of the rotatable member about the axis.
According to another aspect of the invention, there is provided a method of fastening a floor board using a fastening tool having a tool body and a driver, the driver having a percussion head and a fastener head and a transmission element linking the percussion head and the fastener head, the method comprising applying a first percussion drive to the percussion head to drive the percussion head in a first direction, transforming the first percussion drive into a second percussion drive at the transmission train, applying the second percussion drive to the fastener head to drive the fastener head in a second direction to strike a fastener lodged in a strike position in the fastening tool.
For simplicity and clarity of illustration, elements illustrated in the following figures are not drawn to common scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Advantages, features and characteristics of the present invention, as well as methods, operation and functions of related elements of structure, and the combinations of parts and economies of manufacture, will become apparent upon consideration of the following description and claims with reference to the accompanying drawings, all of which form a part of the specification, wherein like reference numerals designate corresponding parts in the various figures, and wherein:
Shown in sectional view in
A driver member 72 is attached to the lower end of piston 58 and is vertically drivable into and out of a straight vertical track section 74 in shoe 14 (
Referring to
The spring steel member 86 is of the order of 0.25 inches in thickness and a half inch in width. It is welded at one end to the rigid driver member 72 and at the other to the blade tip 84 by a tungsten inert gas welding process. As shown in the embodiment of
In use, the fastener driving tool 10 is in a resting position as shown in
When a hammer blow is applied to anvil 40, actuator 48 is driven downwardly in chamber 32 as shown in
As shown by
It can be seen that the vertical reciprocation of the member 72 results in the blade tip driving a staple fastener 21 diagonally into the floorboard 16 as shown in
The blow to anvil 40 only temporarily shifts the pressure balance in the tool main body 12. The pressure balance quickly returns to its initial condition after the hammer blow has been effected and the lead fastener has been driven into a floorboard 16. At this point, poppet valve 48 returns to its resting position owing to the greater pressure applied by the compressed air on the bottom of the actuator 46 than on the top of the poppet valve 48. The poppet valve member 48 sealingly engages the seat 34 once again under the bias of the upwardly moving actuator 46. The compressed air in the chamber 30 above disc 62 flows through holes 66 into piston channel 64, through poppet channel 50 (above sleeve 60) and out of tool 10 through exhaust holes 68 and 70. Once the pressure in lower chamber 30 above disc 62 nears atmospheric pressure, the upward pressure applied by the compressed air against sleeve 60 drive piston 58 upwardly in poppet channel 50 back to its initial upper limit position as shown in
The fastening tool has some tendency to lift slightly from the flooring when a fastener is expelled due to the outcoming fastener hitting the hard floor, which may result in the fastener not being properly driven into the board and subfloor. Because the hammer blow applied to the anvil 40 is downwardly directed, this helps to prevent the tool from this slight upward reaction.
The function of the spring steel member 86 housed within the curved track is to convert the downward motion of the anvil to the diagonal motion of the blade tip. Although the spring steel member (or members) 86 is preferred, the transformation in drive direction can be effected with alternative mechanical devices. In one alternative, as shown in
In a further embodiment as shown in
In yet another embodiment, the transformation from vertical hammer direction to diagonal drive bit direction might be achieved using a rotary member having a first lug positioned in the path of the driver member in the fastener ready position to enable the rotary member to be turned as the first lug is truck by the downwardly moving driver member. The rotary member can have a second lug position so that as the rotary member rotates, the second lug collides with the drive bit to drive the drive bit against a readied fastener.
It will be appreciated that in each of the foregoing embodiments, the blade tip is driven by the spring steel driver to eject the readied fastener out of the fastening tool and into the floorboard to be fastened generally at the corner between the bottom edge of the board and the upwardly orientated face of the tongue. The force applied to the fastener is diagonally directed and so one component of this acts to drive the board being fastened against the previously laid board to squeeze the two boards together at the moment of impact.
While the specific embodiments described above relate to a board fastening tool for fastening a floor board to an underlying structure such as a subfloor, it will be appreciated that the principles of the invention can be used on other fastening tools such as trim guns and framing guns where space in relation to a “finishing” wall or other limiting surface or object means that the actuating room for the tool is limited. Tools of a range of sizes, both manually operated and power assisted can use the principles of the invention.
Other variations and modifications will be apparent to those skilled in the art. The embodiments of the invention described and illustrated are not intended to be limiting. The principles of the invention contemplate many alternatives having advantages and properties evident in the exemplary embodiments.
