U.S. patent application number 10/195207 was filed with the patent office on 2004-01-15 for method and apparatus for attaching structural components with fasteners.
Invention is credited to Haytayan, Harry M..
Application Number | 20040006860 10/195207 |
Document ID | / |
Family ID | 30114933 |
Filed Date | 2004-01-15 |
United States Patent
Application |
20040006860 |
Kind Code |
A1 |
Haytayan, Harry M. |
January 15, 2004 |
Method and apparatus for attaching structural components with
fasteners
Abstract
A method and apparatus for fastening a first relatively soft
structural component such as a wood panel to a second relatively
hard structural component such as a steel angle iron using
fasteners each having a forward self-drilling portion, a rearward,
self-tapping portion, and an outwardly projecting head. The
fasteners are driven by a pneumatic rotary impact driver and the
method comprises rotatively driving each fastener so as to cause
its self-drilling portion to drill a first hole through the wood
panel and thereafter rotatively. driving and impacting that
fastener so as to cause its self-drilling portion to drill a second
hole in the angle iron and its self-tapping portion to form a screw
connection with the angle iron around the second hole.
Inventors: |
Haytayan, Harry M.; (Nashua,
NH) |
Correspondence
Address: |
Nicholas A. Pandiscio
Pandiscio & Pandiscio, P.C.
470 Totten Pond Road
Waltham
MA
02451-1914
US
|
Family ID: |
30114933 |
Appl. No.: |
10/195207 |
Filed: |
July 15, 2002 |
Current U.S.
Class: |
29/525.01 |
Current CPC
Class: |
Y10T 29/49963 20150115;
F16B 25/0031 20130101; B25B 21/023 20130101; B25B 23/045 20130101;
Y10T 29/49947 20150115; B25B 23/0035 20130101; F16B 27/00 20130101;
Y10T 29/49833 20150115; F16B 25/10 20130101; Y10T 29/53478
20150115; B25B 23/04 20130101; B25B 21/02 20130101; B25B 21/002
20130101; Y10T 29/53487 20150115; B25B 23/06 20130101 |
Class at
Publication: |
29/525.01 |
International
Class: |
B23P 011/00 |
Claims
What is claimed is:
1. Method of attaching a relatively soft structural member to an
underlying relatively hard structural member made of metal, said
method comprising the steps of: (a) providing fasteners comprising
a shank having a head at one end, a tapered point at the opposite
end, a drill portion that extends away from said tapered point for
a fixed distance, and a screw portion commencing from adjacent said
drill portion and extending toward said head; and (b) driving said
fasteners through said relatively soft structural member into said
relatively hard structural member by first rotating them to cause
said drill portion to penetrate said relatively soft structural
member in a drilling action and then, when said fasteners have
engaged said relatively hard structural member, repetitively
impacting said fasteners while simultaneously subjecting them to
rotational torque, whereby to cause said fasteners to penetrate
said relatively hard structural member and lock said relatively
soft structural member to said to relatively hard structural
member.
2. Method according to claim 1 wherein (1) said drill portion
drills aligned holes in said relatively soft structural member and
said relatively hard structural member, and (2) said screw portion
cuts a helical screw thread in and makes a screw connection with
said relatively hard structural member.
3. Method according to claim 2 wherein the diameter of said screw
portion exceeds the diameter of said drill portion.
4. Method according to claim 3 wherein said drill portion comprises
helical cutting flutes and said screw portion comprises a helical
screw thread.
5. Method according to claim 1 wherein said first structural member
is made of a hard wood material and said second structural member
is made of a metal.
6. Method according to claim 5 wherein said second structural
member is made of steel.
7. Method according to claim 5 wherein said second structural
member comprises a structural portion of a shipping container,
truck body or truck trailer body.
8. Method according to claim 1 wherein said fasteners are mounted
in a plastic strip that comprises a plurality of hollow cylindrical
carriers attached to one another in series, with each fastener
mounted in its own carrier, and further wherein step (b) involves
driving said fasteners out of said carriers without separating said
carriers from one another.
9. Method according to claim 1 wherein said carriers have top and
bottom end surfaces and said shanks of said fasteners are gripped
by said carriers with said fastener heads extending above said top
end surfaces of said carriers, and further wherein said fastener
heads have a maximum diameter not exceeding the inner diameter of
said hollow cylindrical carriers, whereby to facilitate expelling
said fasteners lengthwise out of said bottom ends of said carriers
responsive to rotational forces applied to said heads of said
fasteners.
10. Method according to claim 9 wherein each of said cylindrical
carriers has inwardly facing ribs that surround and grip the shank
of one of said fasteners.
11. Method according to claim 9 where the heads of said fasteners
are provided with cutting blades for cutting away said ribs as said
fasteners are rotatively driven in a direction to expel them from
said carriers.
12. Method according to claim 1 wherein said fasteners are driven
according to step (b) by means of a pneumatic rotary impact
driver.
13. Apparatus for use in attaching structural members to one
another using fasteners comprising: a rotary impact driver having
an output spindle, said driver being operable on command to rotate
said spindle and to repetitively impact said spindle when said
spindle encounters a predetermined level of resistance to rotation;
means connected to said spindle for supporting a tool bit in
coaxial relation with said spindle so that rotational and rotary
impact forces generated by said driver will be transmitted to said
tool bit; a positioning plate, said positioning plate having a top
end surface and a bottom end surface, a fastener drive bore
extending between and through said top and bottom surfaces, said
fastener drive bore being coaxial with said spindle; and
telescoping means coupling said positioning plate to said driver so
that said driver and said spindle can be moved toward and away from
said top end surface of said positioning plate; whereby when said
bottom end surface of said positioning-plate is positioned on a
first structural member that is to be attached to an underlying
second structural member, said telescoping means permits said
driver and spindle to be moved toward said first structural member
to bring a tool bit attached to said spindle into engagement with
the head of a fastener positioned in said fastener drive bore, so
that operation of said driver will cause said fastener to be driven
through said first structural member into said second structural
member under the rotational and impact forces transmitted to said
spindle by said driver.
14. Apparatus according to claim 13 further including biasing means
urging said telescoping means in a direction to move said driver
away from said top end surface of said positioning plate.
15. Apparatus according to claim 13 further including a tool bit
attached to said spindle and extending into said fastener drive
bore of said positioning plate.
16. Apparatus according to claim 15 wherein said tool bit is
attached to said spindle by a quick-release connection means.
17. Apparatus according to claim 13 further including a magazine
attached to said positioning plate having means for holding a strip
of fasteners arranged in single file and means for feeding those
fasteners into said fastener drive bore in position for driving
engagement by a tool bit attached to said drive shaft.
18. Apparatus according to claim 17 further including travel
limiting means for limiting the extent of movement of said driver
relative to said fastener positioning plate.
19. Apparatus according to claim 18 wherein said travel limiting
means includes a member movable with said driver and engageable
with said positioning plate, said member being adjustable to vary
the distance that said driver can move toward said positioning
plate.
20. Apparatus according to claim 13 further including pneumatic
means for applying a pneumatic force to said telescoping means so
as to cause said telescoping means to move said driver and said
spindle away from said top end surface of said positioning plate to
a limit position.
21. Apparatus according to claim 20 further including valve means
for controlling application of said pneumatic driving force to said
telescoping means, and manually operated means for operating said
valve means so as to terminate application of said pneumatic force
to said telescoping means.
22. Apparatus according to claim 21 wherein said driver is a
pneumatic driver, and further wherein control means also controls
operation of said pneumatic driver.
23. Apparatus for use in connecting structural members together by
means of fasteners, said apparatus comprising: a pneumatically
powered rotary impact driver having a housing and an output spindle
extending from said housing, said driver being adapted for
connection to a source of pressurized fluid for powering the driver
and being activatable, when connected to said source of pressurized
fluid, to rotatively drive said spindle and also to repetitively
impact said spindle when said spindle encounters a predetermined
level of resistance to rotation; a torque and impact transmitting
unit comprising an elongate barrel having first and second ends and
an axial bore, means at said first end of said barrel for securing
said barrel to said driver, and a drive shaft attached to and
coaxial with said spindle so as to form an extension of said
spindle, said drive shaft being disposed within said axial bore and
having an outer end remote from said spindle; a positioning plate,
said positioning plate having a top end surface and a bottom end
surface, and a fastener drive bore extending between and through
said top and bottom surfaces, said fastener drive bore being
coaxial with said axial bore; telescoping means coupling said
positioning plate to said barrel so that said barrel and said drive
shaft can be moved toward and away from said top end surface of
said positioning plate; pneumatic means for urging said telescoping
means to move in a direction to move said barrel and said drive
shaft away from said top end surface of said positioning plate when
said driver is coupled to a source of pressurized fluid; connection
means for coaxially attaching to said outer end of said drive shaft
a tool bit that is adapted to make a locking engagement with the
head of a fastener positioned in said fastener drive bore; and
means for deactivating said pneumatic means whereby to allow said
telescoping means to move in a direction to move said barrel and
said drive shaft toward said positioning plate, whereby when said
bottom end surface of said positioning plate is positioned on a
first structural member that is to be attached to a second
underlying structural member, said torque and impact transmitting
unit can be moved toward said member to bring a tool bit attached
to said drive shaft into engagement with the head of a fastener
positioned in said fastener drive bore, so that operation of said
driver will cause said fastener to be driven through said first
structural member into said second structural member under the
rotational and impact forces transmitted by said drive shaft and
said tool bit.
24. Apparatus according to claim 23 further including means for
introducing fasteners into said fastener drive bore in position for
driving engagement by a tool bit attached to said drive shaft.
25. Apparatus according to claim 23 wherein said barrel has a pair
of longitudinally extending slide bores, and said telescoping means
comprises a pair of slide rods slidably received in slide bores,
with said slide rods having outer ends attached to said positioning
plate.
26. Apparatus according to claim 25 wherein said slide rods have
inner ends disposed in said slide bores, and said pneumatic means
comprises means for injecting pressurized fluid into said slide
bores so as to pneumatically force said slide rods to move in said
slide bores toward said positioning plate.
27. Apparatus according to claim 23 further including adjustable
stop means for limiting movement of said barrel and said drive
shaft toward said positioning plate.
28. Apparatus according to claim 23 further including a tool bit
attached to said outer end of said drive shaft by said connection
means for engagement with a fastener positioned in said fastener
drive bore.
29. Apparatus according to claim 23 wherein said driver has a
handle, and further including an auxiliary handle attached to said
torque and impact transmitting unit adjacent to said driver,
whereby said apparatus may be held by an operator's two hands when
used to drive fasteners.
30. Apparatus according to claim 23 further including a magazine
attached to said positioning plate having means for holding a strip
of fasteners arranged in single file and means for feeding those
fasteners into said fastener drive bore in position for driving
engagement by a tool bit attached to said drive shaft.
31. Apparatus according to claim 30 wherein said magazine is
adapted to support a fastener clip comprising a plastic strip in
the form of a plurality of sleeves attached to one another in
series, and a plurality of fasteners disposed within and supported
by said sleeves.
32. Apparatus according to claim 30 wherein said magazine extends
laterally of said positioning plate.
33. Apparatus according to claim 23 further including a multi-port
control valve means for controlling application of pressurized
fluid to said pneumatic means and said driver, and further wherein
said means for deactivating said pneumatic means comprises
manually-operable means for controlling operation of said control
valve means.
34. Apparatus for use in connecting structural members to one
another by means of fasteners, said apparatus comprising: a rotary
impact driver having a housing and an output spindle extending from
said housing, said driver being operable on command to rotate said
spindle and to repetitively impact said spindle when said spindle
encounters a predetermined level of resistance to rotation; a
torque and impact transmitting unit coupled to said driver, said
unit comprising an elongate barrel having first and second ends and
an axial bore, an attachment means at said first end of said barrel
for securing said barrel to said driver, and a drive shaft attached
to and coaxial with said spindle so as to form an extension of said
spindle, said drive shaft being disposed within said axial bore and
having an outer end remote from said spindle; a positioning plate,
said positioning plate having a top end surface and a bottom end
surface, a fastener drive bore extending between and through said
top and bottom surfaces, said fastener drive bore being coaxial
with said drive shaft; telescoping means coupling said positioning
plate to said barrel so that said barrel and said drive shaft can
be moved toward and away from said top end surface of said
positioning plate; and means for coaxially attaching to said outer
end of said drive shaft a tool bit that is adapted to make a
locking engagement with the head of a fastener positioned in said
fastener drive bore, whereby when said bottom end surface of said
positioning plate is positioned on a member that is to be attached
to an underlying substrate, said torque and impact transmitting
unit can be moved toward said member to bring a tool bit attached
to said drive shaft into engagement with the head of a fastener
positioned in said fastener drive bore, so that operation of said
driver will cause said fastener to be driven through said member
into said substrate under the rotational and impact forces
transmitted by said drive shaft and said tool bit.
35. Apparatus according to claim 34 further including biasing means
for urging said telescoping means in a direction to move said
barrel and said drive shaft away from said top end surface of said
positioning plate.
36. Apparatus according to claim 35 wherein said biasing means
comprising mechanical spring means.
37. Apparatus according to claim 35 wherein said biasing means
comprises pneumatic means.
38. Apparatus according to claim 34 further including a magazine
attached to said positioning plate having means for holding a strip
of fasteners arranged in single file and means for feeding those
fasteners into said fastener drive bore in position for driving
engagement by a tool bit attached to said drive shaft.
39. Apparatus according to claim 34 wherein said driver is a
pneumatic rotary impact driver.
40. Apparatus according to claim 34 wherein said telescoping means
comprises a pair of longitudinally extending slide bores in said
barrel, and a pair of slide rods slidably received in slide
bores.
41. Apparatus according to claim 40 wherein said slide rods have
heads slidably disposed in said slide bores and said slide bores
and said heads form cylinder/piston arrangements, and further
wherein said biasing means comprises means for delivering a
pressurized fluid to and removing pressurized fluid from said slide
bores, whereby pneumatic forces may be applied to or removed from
said heads to vary the position of said slide rods in said slide
bores.
42. Apparatus according to claim 40 wherein said biasing means
includes means for causing automatic delivery of pressurized fluid
to said slide bores when said barrel and said drive shaft have
moved a predetermined distance toward said positioning plate.
43. Apparatus according to claim 40 further including manually
operated means for terminating application of pressurized fluid to
said slide bores.
44. Apparatus according to claim 40 wherein said biasing means
comprises springs disposed in said slide bores and acting on said
slide rods.
45. Apparatus according to claim 17 wherein each of said fasteners
has a head with a conically shaped side surface, and a plurality of
mutually spaced cutting blades protruding from said side surface
for cutting a countersink for said head in a structural member when
said each fastener is rotatively driven through said structural
member.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to attaching
structural elements with fasteners, and more particularly to a
novel method and apparatus for fastening structural elements
together with fasteners.
BACKGROUND OF THE INVENTION
[0002] It is well known to use screws and nails, or similar
pin-type fasteners, for securing floor, wall and ceiling panels to
supporting structures in buildings and vehicle cargo container
bodies. In the case of truck trailer bodies, hard wood floors are
attached to a metal frame or substrate. The typical truck trailer
body has a steel frame, and the hardwood flooring is secured to the
steel frame with metal fasteners. One common technology for
securing floors to truck trailer bodies requires pre-drilling holes
in both the wood flooring and the underlying metal frame, e.g.,
steel angle irons and/or I-beams, and applying self-tapping screws
through those holes to anchor the flooring to the frame. In some
cases, vehicle cargo bodies or personnel-containing structures,
e.g., mobile homes, may use aluminum framing. Since aluminum frame
members are more easily penetrated than steel frame members of the
same thickness, wood flooring and wall and ceiling panels may be
attached to aluminum framing by means of nail-type pins with spiral
grooves disposed along a portion of their length, with those pins
being driven through the flooring and into aluminum frame members
by means of a pneumatic high impact driver, e.g., a driver as
disclosed in my U.S. Pat. No. 5,645,208, issued Jul. 8, 1997 and
U.S. Pat. No. 4,040,554, issued Aug. 9, 1977. However, applying
such pins with a pneumatic high impact driver has limitations with
respect to attaching hard wood flooring to steel framing. For one
thing, the high impact produced by such a driver tends to split the
hardwood flooring. Also, some steel framing members are not readily
penetrated by the pins under the force exerted by the high impact
driver, particularly when the steel frame members have a thickness
of 1/8 inch or greater. Moreover, since it is strictly an impact
driving procedure, when a fastener is driven through the flooring
member into an underlying steel frame member, the fastener may not
be driven in far enough to force the flooring member into a tight
fit with the frame, resulting in it not passing inspection
requirements. Consequently the procedure using predrilled holes and
self-tapping screws has become standard industry practice, even
though it is slow due to the need to pre-drill the members to be
secured together. Nevertheless, in an attempt to avoid the
necessity of pre-drilling the underlying frame members,
driver/fastening systems have been conceived whereby special high
carbon steel self-drilling wing screws are applied using a high
speed screw-driving tool. One such system is made by Muro
Corporation of Tokyo, Japan and comprises its model FLVL41
pneumatic power screwdriver and its Super Wing screws. Those
products can be viewed at the web-site "muro.com". The
self-drilling wing screws comprise a forward drill portion, a
rearward screw portion, and usually a pair of laterally-projecting
wings between the drill and screw portions that serve to form
oversize holes in the wood flooring, thereby assuring that the
panels will not lift away from the underlying steel frame as a
reaction to the rapidly rotating screw portion. The wings break off
when they encounter the underlying metal frame members. Such
systems are suitable for penetrating mild steel frame members in
thicknesses up to about {fraction (3/16)} inch. However, an
impedance to exclusive use of such high speed screw-driving systems
using self-drilling wing screws is that trailer body manufacturers
are now preferring to use a high tensile strength steel having a
tensile strength of 80,000 psi and a yield strength of
approximately 50,000-65,000 psi. It is difficult to reliably
penetrate that kind of steel in a thickness of 1/8" using the
self-drilling wing screws and a high speed screw-driver. A
particular problem is that the fast rotating screws tend to burn
due to the heat buildup. Similarly, slow rotating screws do not
develop enough torque to penetrate the steel substrate. Therefore,
there exists a need for an improved fastening method and apparatus
which can reliably attach wood flooring to high tensile strength
steel substrates having a thickness in the order of 1/8" or
greater.
OBJECTS AND SUMMARY OF THE INVENTION
[0003] The primary object of this invention is to overcome the
limitations of the prior art with respect to attaching hardwood
flooring to steel substrates, notably in the attachment of flooring
to trailer truck bodies, large shipping containers and similar
structures.
[0004] A more specific object of the invention is to provide a
method of attaching fasteners that combines the driving force of a
pneumatic rotary impact driver with the economies of self-drilling
screws.
[0005] A more specific object of the invention is to provide a
method of applying fasteners wherein (a) drilling penetration and
(b) self-tapping screw attachment of the fasteners are achieved by
sequential application of a rotational driving force and a
rotational impact driving force.
[0006] Another object of the invention is to provide an apparatus
for attaching wood structural members to metal substrates wherein
the apparatus comprises drive means for rotatively driving
self-drilling, self-tapping fasteners through the wood structural
members and also rotatively impacting the fasteners to facilitate
penetration of and attachment to the metal substrates.
[0007] Still another object is to provide a means of attaching wood
flooring to steel substrates using self-drilling screw fasteners
that do not require wings to prevent the flooring from lifting up
as the fasteners are driven into the steel substrates.
[0008] These and other objects are achieved by providing a tool
that comprises means for supporting a self-drilling, self-tapping
screw fastener in position to be driven, drive means for rotatively
driving the fastener through a first relatively soft structural
element until it encounters a second relatively hard structural
element made of metal that presents a predetermined level of
resistance to penetration of the fastener, and then simultaneously
rotatively impacting the fastener to overcome the resistance to
penetration, whereby the fastener penetrates the second structural
element by drilling a hole and tapping it to form a screw
connection. A magazine feeds fasteners into position to be driven.
Other features and advantages of the invention are described or
rendered obvious by the following detailed specification.
THE DRAWINGS
[0009] FIG. 1 is a side view in elevation of one embodiment of the
invention;
[0010] FIG. 2 is a front view in elevation of the same tool;
[0011] FIG. 3 is a fragmentary longitudinal center sectional view
of the same tool;
[0012] FIG. 4 is a fragmentary longitudinal center sectional view
taken at a right angle to FIG. 3;
[0013] FIG. 5 is a fragmentary longitudinal center sectional view
that forms an extension of FIG. 4;
[0014] FIG. 6 is a fragmentary longitudinal center sectional view
that forms an extension of FIG. 3;
[0015] FIG. 7 is an enlargement of a portion of FIG. 6;
[0016] FIG. 8 is a rear view in elevation of the face plate that
serves as a guide for fasteners and their supporting strip;
[0017] FIG. 9 is a sectional view taken along line 9-9 of FIG.
8;
[0018] FIG. 10 is a front view of the same face plate;
[0019] FIG. 11 is a plan view, with a portion shown in section, of
the same face plate;
[0020] FIG. 12 is a longitudinal center line section in side
elevation of the fastener clip magazine;
[0021] FIG. 13 is a front end view in elevation of the fastener
clip magazine;
[0022] FIG. 14 is a cross-sectional view of a fastener clip;
[0023] FIG. 15 is a bottom view of a portion of the
fastener-holding strip;
[0024] FIG. 16 is a plan view of the head of a fastener;
[0025] FIG. 17 is a plan view of the head of an alternative
fastener;
[0026] FIG. 18 is a side view in elevation of a preferred
embodiment of the invention;
[0027] FIG. 19 is a front view in elevation of the apparatus shown
in FIG. 18;
[0028] FIG. 20 is a fragmentary sectional view of the apparatus
shown in FIGS. 18 and 19;
[0029] FIG. 21 is a fragmentary sectional view that forms an
extension of FIG. 20;
[0030] FIG. 22 is a fragmentary sectional view taken at a right
angle to FIG. 20;
[0031] FIG. 23 is a fragmentary sectional view that forms an
extension of FIG. 22; and
[0032] FIG. 24 is a schematic view of the pneumatic system embodied
in the apparatus of FIGS. 18-23.
[0033] In the drawings, like parts are identified by like
numerals.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Referring to FIGS. 1 and 2, the illustrated apparatus
includes and utilizes a conventional pneumatically-powered rotary
impact driver 2 that preferably, but not necessarily, is adapted to
operate in both forward and reverse directions. Such tools,
commonly known as rotary impact wrenches, are made and sold by
numerous companies and their construction is exemplified by the
devices shown in the following U.S. Pat. No. 2,463,656, issued Mar.
8, 1949 to F. H. Thomas; U.S. Pat. No. 3,428,137, issued Feb. 18,
1969 to R. J. Schaedler et al; U.S. Pat. No. 4,347,902, issued Sep.
7, 1982 to W. K. Wallace; U.S. Pat. No. 4,951,756, issued Aug. 28,
1990 to R. J. Everett et al; U.S. Pat. No. 5,083,619, issued Jan.
28, 1992 to D. A. Giardino; U.S. Pat. No. 5,320,187, issued Jun.
14, 1994 to J. Pressley; U.S. Pat. No. 5,622,230, issued Apr. 22,
1997 to D. A. Giardino; and U.S. Pat. No. 5,906,244, issued May 25,
1999 to S. C. Thompson. However, for the purposes of this
invention, the tool must be of the type that has two operating
modes, a rotary driving mode and an impact rotary driving mode,
with the tool automatically shifting to its impact rotary driving
mode when the resistance to rotation of the fastener being driven
by the tool attains a predetermined value. One such commercial
impact driver that is usable to practice the present invention is
the Model IR 2131 made by Ingersoll-Rand Co. of 200 Chestnut Ridge
Road, Woodcliff Lake, N.J. 07675.
[0035] Still referring to FIGS. 1 and 2, the driver 2 is attached
to a torque and impact transmitting unit 4 to which is attached a
magazine 6 that carries a supply of fasteners 8 (FIG. 6), as
hereinafter described. Driver 2 has a housing 10 and a handle 12
that is provided with a hose connector 14 for attaching the driver
to a source of high pressure air (not shown) via a flexible hose
line (also not shown). The tool has a trigger 16 that controls its
operation. When the trigger is depressed, high pressure air is
delivered to the operating mechanism of the impact driver.
Referring to FIG. 3, the tool has an output shaft or spindle 18
which is driven by the operating mechanism when trigger 16 is
squeezed to allow high pressure air to enter the tool.
[0036] The torque and impact transmitting unit 4 comprises a hollow
housing 20 (FIG. 3) having a counterbore 22 in one end in which
driver housing 10 is received. The driver is secured to the housing
20 by means of one or more set screws 24, or other suitable
fastening means. Use of set screws facilitates removal of the
torque driver for repair and replacement. An elongate bar 28 has
one end secured by screws 30 to housing 20 in diametrically aligned
relation with driver handle 12, and attached to the other end of
bar 28 is an auxiliary handle 32 that permits two-handed gripping
of the apparatus when it is used to drive fasteners.
[0037] A hollow barrel 34 is attached to the forward end of housing
20. In this connection, housing 20 has a center bore 36 (FIG. 3),
and a counterbore 38 between bore 36 and counterbore 22. As shown
in FIG. 4, two holes 40 having counterbores 42 are provided on
opposite sides of center bore 36. Barrel 34 is secured to housing 4
by machine bolts 44 that are received in holes 40 and counterbores
42 and are screwed into tapped holes 46 in the rear end of barrel
34.
[0038] Referring now to FIGS. 3-6, barrel 34 has a central bore 50
and two additional bores 52 and 53 in diametric alignment with bore
50. Bore 50 accommodates a drive shaft 54 that is attached to the
spindle 18 via a coupling 56. The latter make take various forms,
and preferably it is of a type that readily permits the operator to
disconnect it from spindle 18. The forward (outer) end of bore 50
is slightly enlarged in diameter so as to form a shoulder that acts
as a stop for the outer race of a ball bearing unit 58. The outer
race of the ball bearing unit is held in place against that stop by
a retainer ring 60 received in a groove in the surrounding
cylindrical surface that defines bore 50. The inner race of bearing
unit 58 is engaged by a shoulder or drive shaft. The ball bearing
functions to provide radial support for drive shaft 54 while
facilitating its rotation under the influence of driver 2.
[0039] Bores 52 and 53 contain compression springs 62 and 63. Also
mounted within the bores 52 and 53 are two slide rods 66 and 67
respectively. Outer end portions 52A and 53A of bores 52 and 53
have a slightly reduced diameter so as to form shoulders 68 (FIG.
5) that act as stops for enlarged heads or flanges 70 formed on the
inner ends of the slide rods. Heads 70 are sized to make a close
fit in the bores 52 and 53. The springs 62 and 63 have one end
engaged with the forward end face of housing 20 and the opposite
end engaged with the heads 70 of the two slide rods. The springs
constantly urge rods 66 and 67 to telescope forwardly, i.e.,
outwardly of barrel 34.
[0040] Referring now to FIGS. 5-7, the forward end of drive shaft
54 is provided with connector means, identified generally by
numeral 74 in FIG. 5, for attaching a tool bit 76. The connector
means may take various forms, but preferably it is of the quick
disconnect type. The outer end of barrel 34 is cut away through an
angle of about 140.degree. so as to form an open section 80 that
permits access to connector means 74.
[0041] As shown in FIG. 7, the forward end of drive shaft 54 is
provided with a blind hole in the form of a short coaxial bore 82
of circular cross-section, and also with a radially extending round
hole 84 that intersects axial bore 82. A spherical ball 86 resides
in hole 84, and the inner end of hole 84 has a reduced diameter so
as to prevent ball 86 from fully entering bore 82. The outer
surface of the forward end of shaft 54 has a circular
configuration, and a socket member 90 having a relatively large
circular hole 92 surrounds the forward end of shaft 54 and is
locked thereto by a set screw 94 that is received in a blind hole
in shaft 54. The opposite end of socket member 90 has a square
opening 96 that is sized to receive tool bit 76, the latter also
having a square cross-sectional shape sized to make a close fit in
opening 96, whereby the tool bit is locked against rotation
relative to the socket member. Preferably tool bit 76 is made so
that it is reversible, with each of its opposite ends being adapted
for driving engagement with a fastener having a square socket hole
in it head. More specifically, each end of tool bit 76 is formed
with a fastener-engaging end section 98 that is shaped to fit into
and mate with a recess in the head of fastener 8, as hereinafter
described. By way of example, the two ends of the tool bit may have
a square or cross-sectional shape. Additionally adjacent each of
its opposite ends tool bit 76 has a peripheral circular groove 100
that is coaxial with the tool bit. Grooves 100 have a circular
curvature in cross-section, with the radius of curvature being
sized so as to permit a close fit with ball 86.
[0042] Still referring to FIG. 7, connector means 74 comprises a
lock ring 102 that surrounds the forward end of drive shaft 54.
Lock ring 102 is urged away from bearing 58 by a compression spring
104 that is held against the lock ring by a retaining ring 106
seated in a peripheral groove in shaft 54. A second retaining ring
108 is seated in a second peripheral groove in shaft 54 in position
to limit forward movement of ring 102, i.e., movement away from
retaining ring 106. Lock ring 102 is sized to make a close sliding
fit on shaft 54. However, its inner surface is provided with a
longitudinally-extending slot that is stepped so as to have a first
surface section 112 that lies closest shaft 54, a second surface
section 116 that lies furthest from shaft 54, and a sloping
transition surface section 114. Surface sections 112, 114 and 116
may be flat, but preferably they have a circular curvature in
horizontal cross-section taken from the perspective of FIG. 7. If
those surfaces are curved, their radius of curvature is the same
as, or slightly greater than, the radius of ball 86. The width of
the slot is limited so that its engagement with ball 86 prevents
rotation of lock ring 102 relative to drive shaft 54.
[0043] The tool bit 76 extends into the blind bore 82 of shaft 54
far enough for its groove 100 to be engaged by ball 86. When lock
ring 102 is forced back toward retaining ring 106 far enough to
align its surface section 116 with ball 86, enough clearance is
provided to permit ball 86 to be cammed outwardly clear of the tool
bit when a pulling force is applied to the tool bit to separate it
from the drive shaft. When it is desired to insert the tool bit in
shaft 54, the lock ring 102 is forced manually backward away from
retaining ring 108 far enough to align surface section 116 with
ball 86, thereby allowing the ball to be forced out of the way by
the inwardly moving tool bit. When the groove 100 is again
realigned with ball 86, lock ring 102 is released, whereupon spring
104 returns it to the ball locking position shown in FIG. 7, with
the sloping transition surface section 114 acting to cam the ball
into groove 100. When ball 86 is in groove 100 and engaged by
surface section 112, the ball serves to lock the tool bit against
removal from drive shaft 54. It should be noted that ball 86 does
not bear or transmit any of the torque load when the tool bit is
rotated by drive shaft 54 since the torque transmission is
performed by socket member 90, which is locked to shaft 54 by set
screw 94 and is locked to the tool bit by virtue of having a square
hole 96 that mates with the square cross section of the tool bit
shaft. As is believed obvious, the connector means just described
and illustrated is a quick disconnect locking device.
[0044] In addition to the foregoing, force-transmitting unit 4 also
carries a screw bolt 120 which is received in a threaded opening
121 in the forward end of barrel 34. A lock nut 122 is screwed onto
bolt 120 in position to engage the end face 35 of barrel 34,
whereby to lock bolt 120 in a selected position. The head of bolt
120 functions as a stroke limiter acting in conjunction with a stop
member 124 carried by a face or positioning plate 130 described
below. Bolt 120 is extended or retracted as required to assure that
the fasteners 8 are fully seated in the wood/steel substrate.
[0045] Referring now to FIGS. 5, 6 and 8-11, the outer ends of
slide rods 66 and 67 are secured in blind holes 132 in face plate
130, preferably by lock pins 133. Face plate 130 has a round bore
134 that extends parallel to holes 128 and is sized to receive tool
bit 76 in a close fit. Bore 134 extends for only part of the length
(the vertical dimension as seen in FIGS. 6 and 9) of the face
plate, the inner end of bore 134 merging with an enlarged opening
136 that extends through the outer (bottom) end surface 138 of the
face plate and serves as an exit passageway through which fasteners
are driven into a workpiece, e.g., a wood flooring panel overlying
a metal substrate in the form of an I-beam or a U-shaped-channel
member. Face plate 130 has a rear surface 140 and a front surface
142. Rear surface 140 is formed with an opening 144 that is of
equal width throughout its length except for a wider section 146
near its top end. The minimum width of opening 144 is large enough
to accommodate fasteners 8 (FIGS. 6, 12 and 14) described
hereinafter and the width of its wider section 146 is made slightly
larger, preferably about 0.015 inch greater, than the width of the
plastic strip 250 that supports fasteners 8. Front surface 142 is
formed with a T-shaped opening 148 that has a wider upper section
150 with a width that is slightly greater than the width (lateral
dimension) of the plastic fastener-supporting strip 250. Opening
148 is aligned with opening 144 and its upper section 150 is
aligned vertically and horizontally with the wide section 146 of
opening 144, whereby its upper section 150 can serve as an exit
path for successive fastener-retaining sleeve sections of plastic
strip 250. Preferably all of the edge surfaces of openings 144 and
the sides of the upper section 150 of opening 148 are chamfered
(beveled) as indicated at 160 and 162.
[0046] Referring to FIGS. 6, 12 and 13, the magazine 6 comprises
opposite end plates 170 and 172 and two parallel and mutually
spaced side plates 174 (only one of which is shown) that are joined
to and extend between the two end plates. The magazine is attached
to face plate 130 by four bolts 178 (FIG. 2) that pass through
aligned holes 182 and 184 in face plate 130 and end plate 172
respectively (FIGS. 8, 13). The spacing between the mutually
confronting inner surfaces 186 of side plates 174 is slightly
greater than the width of strip 250. The inner surfaces 186 are
provided with longitudinally extending ribs 188 that serve as
supporting rails for fastener-supporting strip 250. A pusher member
190 disposed between side plates 174 engages the rear end of strip
250 and pushes it (with its associated fasteners 8) toward end
plate 172. Each side of pusher member 190 has a long rib 191 and a
short rib 193 that overlap the upper and lower sides of the
adjacent rail 188, thereby slidably interlocking the pusher member
to side plates 174 so that the pusher is restricted to straight
line movement toward and away from end plate 172. The pusher member
is urged toward end plate 172 by a constant force coil spring 192
which is rotatably mounted to the pusher member and has its free
end attached by a stud 194 to one of the side plates 174 adjacent
to end plate 172.
[0047] End plate 172 has a through slot 196 that has its width and
height sized to allow passage therethrough of the shanks 212 of
fasteners 8. The upper end of slot 196 has two enlarged sections
198 and 200. Section 198 serves to provide clearance for the short
ribs 193 of pusher member 190. Section 200 is rectangular and has
its width and height sized to allow passage therethrough of strip
250 and the heads of fasteners 8. The inwardly extending ribs 201
defining the upper side of section 200 act to limit vertical
movement of the nail supporting strip 250 while providing clearance
for the upper portion of pusher member 190. Slot 196 is aligned
with opening 144 so that strip 250 and the associated fasteners 8
can pass cleanly through slot 196 and opening 144 into opening 136.
In this connection, it should be noted that when a strip 250
carrying fasteners 8 is supported on rails 188, the heads 214 of
the fasteners will be above the level of the upper edge 151 of the
upper section 150 of opening 148; however, the strip 250 will be
aligned with the upper opening section 150 so that the upper side
strip 250 is slightly below the upper edge 151 of upper opening
section 150. Consequently, (a) when the strip 250 is urged toward
face plate 130 by pusher member 190, it will be stopped as a result
of surface 200 (FIG. 9) of face plate 130 intercepting the head of
the lead (first) fastener carried by the plastic strip, and (b)
after the lead fastener is driven out of the plastic strip by the
tool bit in the manner hereinafter described and the tool bit
withdrawn from opening 134 of face plate 130, the leading (now
empty) fastener-retaining section of the plastic strip will be
forced through the opening 150 until the head of the next-in-line
fastener is intercepted by surface 200.
[0048] Referring to FIGS. 12 and 14, the illustrated fasteners 8
comprises a shank or shaft 212, a head 214 and a pointed tip 216.
Preferably the tip has an apex angle .O slashed. in the range of
about 110.degree. to about 120.degree. so as to facilitate piercing
steel or other metal as hereinafter described. Shaft 212 comprises
a forward self-drilling section that consists of two helical
cutting flutes 218A and 218B that are in diametrically-opposed
relation to one another. Flutes 218A and 218B commence at pointed
tip 216 and extend backwards for a predetermined distance. One side
of each flute terminates in a sharp helical cutting edge 220. Shaft
212 also comprises a rearward self-tapping portion that is
characterized by a screw thread 222 that commences at the rearward
end of cutting flutes 218A, 218B and preferably extends to where
the head 214 joins the shaft. However, it is contemplated that
screw thread may terminate short of the fastener head. Preferably
screw thread 222 has a triangular shape in cross-section, so that
the thread has a sharp cutting edge, and also its maximum diameter
exceeds the maximum diameter of the forward self-drilling section
comprising flutes 218A and 218B. This design allows the fastener to
cut a mating screw thread in the hole formed in a metal substrate
by the drilling flutes. Preferably the thread has a pitch angle in
the range of about 57.degree. to about 63.degree. and a flat
root.
[0049] At the point where screw thread 222 meets the trailing end
of the two cutting flutes, it is provided with longitudinally
extending slot 224. The latter is cut so that one side of the slot
has a flat radially-extending and longitudinally-extending surface
226 that intersects the screw thread in that region of the shaft
and forms a longitudinally extending cutting edge for the leading
portion of the screw thread 222. That cutting edge enables the
leading end of screw thread 222 to cut into a work surface, thereby
enabling the fastener to function as a self-tapping screw.
[0050] The head 214 is formed with a flat top surface 230 and a
tapered side surface 234. Top surface 230 is formed with a suitable
recess for interlocking with a driver tool bit. As illustrated in
FIG. 16, the upper surface 230 preferably is provided with a square
recess 236 for receiving the square end of tool bit 76. Of course,
the recess in surface 30 may have a different shape to accommodate
a tool bit with a different end configuration. Thus, as shown in
FIG. 17, for example, the fastener head may have a multi-lobe
recess 236A, with the lobes 237 being beveled so as to slope
inwardly and downwardly from the surrounding portions of top
surface 230 to facilitate insertion of a Torx.RTM.-style tool bit
of like multi-lobe shape. Additionally, the tapered side surface
234 is formed with a plurality of cutting ribs 240 (a total of
eight ribs is preferred but not essential) which are spaced
uniformly from one another about the circumference of tapered
surface 234. Preferably ribs 240 have a square or rectangular
cross-sectional shape, with the outwardly extending opposite sides
242A and 242B of each rib extending on opposite sides of and
parallel to an imaginary diametrically-extending plane, i.e., a
plane that includes the center axis of the fastener and is equally
spaced from 242A and 242B. The forward edges of flat sides 242A and
242B, i.e., more specifically, the corners formed by those sides
with the outer side of the rib, function as cutting blade edges
depending on the direction of rotation of the fastener.
Alternatively the ribs could be formed with a triangular
cross-sectional shape, with each rib having a first side that
extends outwardly like side 242A or 242B and a second side that
forms the hypotenuse of the triangle and extends from surface 234
to the outer edge of its first side. The corner formed by the
intersection of the outer end of the first side with the second
hypotenuse side serves as a cutting blade edge.
[0051] Referring to FIGS. 12, 14 and 15, the fasteners 8 are
preferably mounted in a plastic mounting strip 250 that comprises a
plurality of cylindrical sleeves 252 which are connected to one
another in series. The strip is formed by injection molding and
sleeves 252 are joined to one another by web portions 254.
Preferably web portions 254 are made as short as is possible within
the limits of injection molding technology. The interior surfaces
256 of sleeves 252 have a constant diameter, except for the
presence of a plurality of radially-extending fastener-retaining
ribs 258. Two of the fastener-retaining ribs of each sleeve,
identified as ribs 258A and 258B, are disposed in line with one
another along the longitudinal axis of the strip. In this
connection it is to be noted that the force exerted by pusher
member 190 tends to compress sleeves 252 along the length of strip
250. Having ribs 258A and 258B aligned with one another offers
resistance to such deformation. Preferably, as shown in FIG. 14,
the bottom ends of ribs 258 are flush with the bottom edge surfaces
260 of the sleeves, but the bottom edge surfaces of the ribs may be
recessed slightly, e.g., about {fraction (1/16)} inch, above the
level of the bottom surfaces 260 without affecting operation of the
invention. Ribs 258 extend for only a small portion of the height
of each sleeve, preferably no more than about one-half of the
height of the sleeves as seen in FIG. 14. Ribs 258 have
substantially identical radial dimensions, with their inner ends
being curved and tangent to a circle having a diameter which is
slightly smaller than the maximum diameter of the threaded portion
of the fasteners, whereby to tightly grip the fasteners. The
fasteners are mounted in the sleeves so that their heads 214 do not
engage the upper end surfaces 262 of the sleeves. In this
connection it is to be noted that the maximum outside diameter of
each head 214 is less than the diameter of the inner surface 256 of
the sleeve in which it is mounted. Ribs 258 grip the threaded
portion of the fasteners and hold them in the sleeves 252.
[0052] The fasteners 8 and the plastic fastener supporting strip
250 are made in accordance with the invention disclosed in my
copending application Ser. No. ______, filed on even date herewith
for "Self-drilling, Self-tapping Screws" (Attorney Docket No.
HMH-91). To the extent necessary, the disclosure of that copending
application is incorporated herein by reference.
[0053] As noted above, the cutting flutes of the forward section of
the shank of each fastener provide the fastener with a
self-drilling capability, while the screw thread that follows the
cutting flutes provides the fastener with a self-tapping and screw
fastening capability. With that combination capability in mind, the
above described apparatus makes it possible to utilize those
fasteners to secure together two structural components without need
for pre-drilling holes in either component.
[0054] Operation of the above described apparatus and the method of
the present invention are now described in relation to applying
fasteners to attach hard wood floor panels to a high tensile
strength steel substrate. Assuming that the apparatus is at rest in
a vertical position, springs 52 and 53 act to hold driver 2 and
tool bit 76 in an elevated standby position (FIGS. 5 and 6) wherein
the tool bit is spaced above the level of the fasteners supplied by
magazine 6 to positioning plate 140. With the driver 2 connected to
a source of pressurized air, and the magazine 6 loaded with a strip
of fasteners 8, the operator places the tool on top of the wood
paneling, depresses trigger 16, and pushes down on handles 12 and
32 to compress springs 62 and 63 enough to bring the rotating tool
bit into engagement with the head of the leading fastener 8 located
in opening 136 of the face plate. The end of the rotating tool bit
will enter the recess 236 (in the case of a square end on the tool
bit) or the recess 236A (in the case of a multi-lobe end on the
tool bit) and then will operate to drive the fastener into the
workpiece. More particularly, with the fastener being driven by the
axially-biased, power-driven rotating tool bit, the cutting flutes
218A and 218B will drill through the wood panel and then drill a
hole in the metal substrate, and when the forward portion of the
screw thread 222 characterized by the slot 224 encounters the hole
in the metal substrate formed by the cutting flutes, the sharp
outer edge of slot surface 226 will cause the leading turns of the
screw thread 222 to commence a screw-tapping operation, whereby
continued rotation of the fastener under the influence of the
downward force exerted by the operator will cause the screw thread
222 to form a mating screw thread in the surrounding metal surface
that defines the hole formed by cutting flutes 218A and 218B, with
the formed screw thread in the metal substrate making a screw
connection with the fastener, whereby the wood panel is secured to
the metal substrate.
[0055] As noted above, heretofore self-drilling, self-tapping
screws could not be driven through hard wood panels into high
tensile strength steel using a powered screwdriver without any
pre-drilling of holes, and that problem has been overcome by using
the pneumatically powered impact torque wrench-type driver 2 to
drive the fasteners. According to this invention, during the time
that the fastener 8 is drilling through the hard wood panel, the
driver 2 is operating as a simple rotating drill/screwdriver.
However, when the tool bit tip 76 encounters increased resistance
from the appreciably harder steel substrate, the driver
automatically shifts to its impact driving mode, and that mode has
the effect of causing the fastener to penetrate the metal
substrate. If the apparatus of this invention is used to drive
fasteners 8 into substrates made of mild steel, the driver may be
able cause the fasteners to penetrate the substrates while
operating in a simple rotational screwdriver mode, but if not it
will automatically shift to its impact driving mode achieve the
desired penetration and tapping action. Of course, in the case
where the metal substrate is aluminum, the driver 2 will operate in
a simple rotational mode to drive the fasteners to the desired
depth.
[0056] An important aspect of the invention is how the fasteners 8
are separated from the supporting plastic strip 250. The axial and
rotational forces exerted on the leading (first-in-line) fastener
in the strip by the torque driver device 2 and tool bit 76 will
cause cutting ribs 240 to rapidly chew away the plastic retainer
ribs 258 of the sleeve 252 that surrounds that fastener. The
removed pieces of ribs 258 and the fastener will pass out of the
bottom of the sleeve as the fastener is driven out of the strip
through the wood panel into the hard metal substrate. Having the
fasteners positioned with their heads elevated above the upper side
of the plastic strip is advantageous in that it allows the
fasteners to achieve a relatively high rotational speed before
their cutting ribs 240 engage the plastic retaining ribs 258,
thereby facilitating rapid cutting away of ribs 258. Also as each
fastener is driven through a hard wood flooring panel into an
underlying metal substrate, the cutting ribs 240 act to cut away
portions of the flooring panel and form a countersink shaped to
accommodate the head of the driven fastener, thereby permitting the
upper surface of the fastener head to be flush with or below the
upper surface of the flooring panel. Once the lead fastener has
been driven, the operator first releases trigger 16 to driver 2 and
then stops pressing down on handles 12 and 32, whereupon springs 62
and 63 push driver 2 upwardly to withdraw the tool bit from face
plate 130. Removal of the tool bit from face plate 130 allows the
pusher to move the plastic strip forward so as to move the now
empty sleeve 252 through opening 150 and position the next-in-line
fastener in bore 136. This action avoids the possibility of
portions of the plastic strip 250 being captivated between the
fastener head and the wood panel.
[0057] Referring now to FIGS. 18-24, the preferred embodiment of
the invention is like the embodiment shown in FIGS. 1-16 in most
respects but differs primarily in that (1) the springs 62 and 63
are replaced by pneumatic means for extending the slide rods 66 and
67 to a position like that shown in FIG. 5, and (2) a different
form of means is used for limiting the extent to which those slide
rods are retracted in the course of a fastener-applying
operation.
[0058] In this preferred embodiment the heads 70 on the inner ends
of slide rods 66 and 67 function as pistons and bores 52 and 53
serve as cylinders. Heads 70 are modified to function as pistons by
the addition of two O-rings 264 that are seated in peripheral
grooves in heads 70 and make a sliding engagement with the
surrounding wall that defines cylinder bores 52 and 53. O-rings 264
serve to prevent air from passing out of bores 52 and 53 via their
smaller diameter sections 52A and 53A. To further assure against
loss of air pressure, additional O-rings 268 are located in grooves
surrounding the outer ends of bores 52 and 53, with the additional
O-rings being sandwiched between barrel 34A and housing 20A. In
this connection it should be noted that housing 20A is essentially
the same as housing 20, except as otherwise described hereinafter.
Housing 20A has two short bores 270 and 271 that are aligned with
and form extensions of bores 52 and 53 respectively. Bores 270 and
52 form one pneumatic cylinder and bores 271 and 53 form a second
pneumatic cylinder. Bores 270 and 271 are provided with side
openings in which are mounted like hose connectors 274 and 275 that
are adapted to be connected to flexible air hoses or tubing and
function as ports through which pressurized air can move into and
out of the two pneumatic cylinders.
[0059] Referring to FIGS. 18, 22 and 23, barrel 34A differs from
barrel 34 previously described in that it is provided with a bore
278 that replaces threaded opening 121. Bore 278 extends for the
full length of barrel 34A and serves to slidably accommodate a push
rod 280. The end of rod 280 that projects out of housing 20A has an
external screw thread and is screwed into a hollow screw 282 that
is screwed into a threaded hole in the upper end of face plate 130.
Screw 282 has a knurled external flange 284 that serves as a
gripping section whereby screw 282 can be rotated, whereby to set
the effective length of rod 280 relative to bore 278. Flange 284
also serves as a fail-safe stop by intercepting the end surface 35
of band 34A. A check nut 285 is screwed onto push rod 280.
[0060] Referring to FIGS. 22 and 24, housing 20A is notched to
provide a recess 286 adjacent to barrel 34A, and mounted to housing
20A in that recess is a conventional pneumatic switch 290 having
two ports 292, 293 and an actuating member represented
schematically at 294 that is aligned with and located proximate to
bore 278 in position to be engaged and depressed by push rod 280. A
second conventional pneumatic switch 296 having ports 298, 299 is
mounted to auxiliary handle 32 (FIG. 20). Switch 296 is mounted so
that its actuating member 300 can be depressed by a finger of an
operator's hand. Pneumatic switches 290 and 296 are normally open,
so that air can flow from between ports 292 and 293 and between 298
and 299 only when their actuating members are depressed by push rod
280 and the operator respectively.
[0061] A four-way pneumatic valve 302 is attached to an outside
surface of housing 20A. Like switches 290 and 296, valve 302 is of
conventional construction. By way of example but not limitation,
switches 290 and 296 may be like the Model PXC-M121 switches sold
by Parker Hannifin of Des Plaines, Ill., and valve 302 may be like
the Model No. PVDC 3422297 four-way power valve sold by Parker
Hannifin. More specifically, as represented schematically in FIG.
24, valve 302 comprises an inlet port 304 adapted for connection to
a source of compressed air at a selected pressure, e.g., 90 psig, a
flow-through port 305 connected to inlet port 304, four exit ports
306, 307, 308 and 309, and two control signal valve ports 310 and
311, respectively. The valve is arranged for shifting air flow from
one to the other of exit ports 306 or 307, and from one to the
other of ports 308 and 309, depending on the air pressure levels at
control signal ports 310 and 311. Valve ports 306 and 309 are open
to the atmosphere and serve as exhaust ports. Valve port 307 is
connected via a suitable flexible hose or plastic tubing (not
shown) to the inlet fitting 14 of pneumatic driver 12. Valve port
308 is connected by similar hose lines or plastic tubing to hose
connectors 274 and 275 for cylinder bores 52/270 and 53/271,
respectively. Valve port 305 is connected by similar conduit means
to port 292 of switch 290 and port 298 of switch 296. Port 293 of
switch 290 and port 299 of switch 296 are similarly connected to
control signal valve ports 310 and 311 respectively.
[0062] Operation of this preferred embodiment is now described in
relation to the apparatus being in a vertical position with
positioning plate 130 and magazine 6 resting on the top surface of
a hard wood panel embodying a high tensile strength steel
substrate. Upon connecting inlet port 304 to a regulated compressed
air supply, e.g., a portable air compressor unit, valve 302 assumes
a first state in which port 307 is connected to exhaust port 306
and port 308 is connected to inlet port 304, whereupon pressurized
air is conveyed to the two cylinders comprising bores 52 and 270
and bore 53 and 271, thereby exerting a pneumatic force on piston
heads 70 which causes slide rods 66 and 67 to be forced outwardly
of barrel 34A. This outwardly extending movement of the slide rods
relative to housing 20A and barrel 34A has the effect of raising
tool 2 and tool bit 76 to a standby position wherein the tool bit
is spaced above the fasteners that are delivered to face plate 130
by magazine 6, essentially the same position as illustrated in
FIGS. 5 and 6. Upon closing of switch 296 by the operator,
compressed air will flow out through port 299 to valve port 311,
whereupon the increased pressure at port 311 will cause the valve
to change states, with port 308 now connected to exhaust port 309
and port 307 now connected to inlet port 304. This results in
exhaustion of pressurized air from the two cylinder bores (52/270
and 53/271), allowing slide rods 66 and 67 to move inwardly of
barrel 34A and thereby allowing the tool to drop down under the
pull of gravity to bring the tool bit into engagement with the
recessed head of the fastener located inside of position plate 130.
When trigger 16 of pneumatic driver 12 is depressed, it allows
compressed air supplied via valve port 307 to operate the driver
causing the tool bit to rotate to drive the fastener with which it
is engaged in the manner previously described.
[0063] As with the embodiment first described herein, trigger 16 of
driver 2 may be depressed to operate the driver, before or after
the tool bit has contacted the lead fastener 8 located within
positioning plate 130. Push rod 280 is set so that it engages and
depresses the actuating member 300 of switch 290 just as the
fastener becomes fully seated in the top layer of the wood/metal
substrate, whereupon switch 290 changes state, causing its port 292
to be connected to its port 293 and thereby allowing high pressure
air to be sent as a signal to valve port 310. The application of
high pressure air at port 310 causes valve 302 to reverse states so
that port 307 is again connected to exhaust port 306 and port 308
is again connected to inlet 304, whereupon (a) pressurized air is
reapplied to cylinder bores 270, 52 and 271, 53 to raise tool bit
76 to its original standby position and (b) flow of pressurized air
to the driver is terminated causing the driver to stop rotating the
tool bit even though trigger 16 is still depressed.
[0064] The primary advantage of the preferred embodiment is that,
unlike the other embodiment shown in FIGS. 1-17, no downward
pressure needs to be exerted by the operator to bring the tool bit
into engagement with the fastener to be driven, thereby reducing
operator fatigue. A second advantage of the preferred embodiment
over the embodiment of FIGS. 1-17 is that the driver stops driving
the fastener automatically when the fastener has been driven to the
desired depth, thereby preventing premature wearing or shearing of
the tool bit (a time and cost savings) and assuring consistent
depth of penetration of the fasteners into the wood/metal
substrate.
[0065] A further important advantage of the method of this
invention is that it may be practiced without using telescoping
torque and impact transmitting unit 4 and the magazine 6. More
specifically and by way of example, the method of the invention may
be practiced by using a pneumatic rotary impact driver of the type
described having a tool chuck and a tool bit mounted in the tool
chuck, and using that driver/tool bit apparatus to drive fasteners
that are positioned on the wood/metal substrate manually or by some
convenient fastener-supporting means. Of course, the invention is
not limited to attaching wood floor and wall panels to metal
substrates but may be used to attach other structural components to
one another. Still another advantage of this invention is that the
fasteners may be removed by the simple expedient of engaging the
heads of the fasteners with the appropriate tool bit attached to a
reversible pneumatic driver, and operating that driver in reverse.
This is important in the case of repairs to trailer bodies that
involve removal of hard wood floor or wall paneling.
[0066] Other advantages and modifications of the invention will be
obvious to persons skilled in the art from the foregoing
description and the attached drawings.
* * * * *