U.S. patent application number 11/368733 was filed with the patent office on 2007-09-06 for plastic composite deck screw.
Invention is credited to Daniel Onofrio.
Application Number | 20070204552 11/368733 |
Document ID | / |
Family ID | 38470260 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070204552 |
Kind Code |
A1 |
Onofrio; Daniel |
September 6, 2007 |
Plastic composite deck screw
Abstract
A deck screw for use with plastic and plastic composite deck
materials has a shank with a lower segment having a right hand
thread and an upper segment having a left hand thread. The upper
left hand threaded section has a major diameter which is the same
as or slightly less than the major diameter of the lower right hand
threaded section. The deck screw evacuates and eject loose material
cut out from the deck material as the screw penetrates the deck
material, preventing undesirable unsightly deformation of the deck
upper surface.
Inventors: |
Onofrio; Daniel; (East
Windsor, CT) |
Correspondence
Address: |
JAMES R. CYPHER
405 14TH STREET
SUITE 1607
OAKLAND
CA
94612
US
|
Family ID: |
38470260 |
Appl. No.: |
11/368733 |
Filed: |
March 6, 2006 |
Current U.S.
Class: |
52/698 |
Current CPC
Class: |
F16B 25/0057 20130101;
F16B 35/06 20130101; F16B 2033/025 20130101; F16B 5/0275 20130101;
F16B 25/0031 20130101 |
Class at
Publication: |
052/698 |
International
Class: |
E04B 1/38 20060101
E04B001/38 |
Claims
1. A deck screw for fastening a workpiece to a base member,
comprising: a shank having a lower segment having a right hand
thread and an upper segment having a left hand thread, said right
hand thread of said lower segment having a right hand thread major
diameter, said right hand thread and said left hand thread being
adjacent each other without a substantial gap therebetween, said
left hand thread of said upper segment having a left hand thread
major diameter, said left hand thread major diameter being equal to
or slightly less than said right hand thread major diameter; and a
head having means for engagement by a fastener driving tool.
2. The deck screw of claim 1 wherein said left hand thread major
diameter is slightly less than said right hand thread major
diameter.
3. The deck screw of claim 2 wherein said left hand thread major
diameter is 0.10 mm or less smaller than said right hand thread
major diameter.
4. The deck screw of claim 2 wherein said right hand thread of said
lower segment and said left hand thread of said upper segment are
adjacent each other and provide a length of the threaded portions
of the shank, and wherein said right hand thread of said lower
segment comprises from about 45 percent to about 80 percent of the
length of the threaded portions of the shank.
5. The deck screw of claim 4 wherein said right hand thread of said
lower segment and said left hand thread of said upper segment are
adjacent each other and provide a length of the threaded portions
of the shank, and wherein said right hand thread of said lower
segment comprises from about 60 percent to about 70 percent of the
length of the threaded portions of the shank.
6. The deck screw of claim 4 wherein said screw has a total length
of about 70 mm, and said left hand thread of said upper segment has
a length of between 15-17 mm, and said right hand thread of said
lower segment has a length of the between 43-46 mm.
7. The deck screw of claim 1 wherein said head has a lower surface
with an annular channel surrounding said shank.
8. The deck screw of claim 1 wherein said left hand thread has a
left hand thread angle and the right hand thread has a right hand
thread angle, and the left hand thread angle is greater than the
right hand thread angle.
9. The deck screw of claim 8 wherein said left hand thread has a
left hand thread angle of between about 30.degree. to about
45.degree. and said right hand thread has a right hand thread angle
of between about 25.degree. to about 40.degree..
10. The deck screw of claim 8 wherein said left hand thread has a
left hand thread angle of about 40.degree. and said right hand
thread has a right hand thread angle of about 30.degree..
11. The deck screw of claim 1 wherein said left hand thread has a
left hand thread pitch and the right hand thread has a right hand
thread pitch, and the right hand thread pitch is larger than the
right hand thread pitch.
12. The deck screw of claim 11 wherein said left hand thread pitch
has a left hand thread pitch of between about 1.8 mm to about 2.8
mm and said right hand thread has a right hand thread pitch of
between about 2.3 mm to about 3.2 mm.
13. The deck screw of claim 12 wherein said left hand thread pitch
has a left hand thread pitch of about 2.3 mm and said right hand
thread has a right hand thread pitch of about 2.8 mm.
14. A deck screw for fastening a workpiece to a base member,
comprising: a shank having a lower segment having a right hand
thread and an upper segment having a left hand thread, said right
hand thread of said lower segment having a right hand thread major
diameter, said right hand thread and said left hand thread being
positioned to form a continuous thread pattern, said left hand
thread of said upper segment having a left hand thread major
diameter, said left hand thread major diameter being slightly less
than said right hand thread major diameter; said right hand thread
of said lower segment and said left hand thread of said upper
segment provide a length of the threaded portions of the shank, and
wherein said right hand thread of said lower segment comprises from
about 45 percent to about 80 percent of the length of the threaded
portions of the shank; said left hand thread having a left hand
thread pitch and the right hand thread having a right hand thread
pitch, said right hand thread pitch being larger than said right
hand thread pitch; said left hand thread having a left hand thread
angle and the right hand thread having a right hand thread angle,
said left hand thread angle being greater than said right hand
thread angle; and a head having means for engagement by a fastener
driving tool having a lower surface with an annular channel
surrounding said shank.
15. The deck screw of claim 14 wherein said left hand thread major
diameter is 0.25 mm or less smaller than said right hand thread
major diameter.
16. The deck screw of claim 15 wherein said left hand thread major
diameter is 0.10 mm or less smaller than said right hand thread
major diameter.
17. The deck screw of claim 16 wherein said right hand thread of
said lower segment comprises from about 60 percent to about 70
percent of the length of the threaded portions of the shank.
18. The deck screw of claim 17 wherein said left hand thread pitch
has a left hand thread pitch of between about 1.8 mm to about 2.8
mm and said right hand thread has a right hand thread pitch of
between about 2.3 mm to about 3.2 mm.
19. The deck screw of claim 18 wherein said left hand thread pitch
has a left hand thread pitch of about 2.3 mm and said right hand
thread has a right hand thread pitch of about 2.8 mm.
20. The deck screw of claim 18 wherein said left hand thread has a
left hand thread angle of between about 30.degree. to about
45.degree. and said right hand thread has a right hand thread angle
of between about 25.degree. to about 40.degree..
21. The deck screw of claim 20 wherein said left hand thread has a
left hand thread angle of about 40.degree. and said right hand
thread has a right hand thread angle of about 30.degree..
22. The deck screw of claim 1 wherein said right hand thread and
said left hand thread are positioned to form a continuous thread
pattern.
23. A method of mounting a plastic or plastic composite board to a
base member, using a deck screw having a shank having a lower
segment having a right hand thread and an upper segment having a
left hand thread, said right hand thread of said lower segment
having a right hand thread major diameter, said right hand thread
and said left hand thread being adjacent each other without a
substantial gap therebetween, said left hand thread of said upper
segment having a left hand thread major diameter, said left hand
thread major diameter being equal to or slightly less than said
right hand thread major diameter, said screw having a head having
means for engagement by a fastener driving tool, comprising the
steps of: engaging said means for engagement with a fastener
driving tool; rotating said deck screw in a clockwise direction to
drive said deck screw into said board by engagement of said right
hand thread of said lower segment with said board and subsequently
with said base member, thereby forming loose material in said
board, said left hand thread of said upper section evacuating and
ejecting at least a portion of said loose material; and said screw
head being drawn down into and seated in said board until a screw
upper surface is substantially flush with an upper surface of said
board and said upper surface of said board is not substantially
deformed.
24. A method of mounting a plastic or plastic composite board to a
base member, using a deck screw having a shank having a lower
segment having a right hand thread and an upper segment having a
left hand thread, said right hand thread of said lower segment
having a right hand thread major diameter, said right hand thread
and said left hand thread being adjacent each other without a
substantial gap therebetween, said left hand thread of said upper
segment having a left hand thread major diameter, said left hand
thread major diameter being slightly less than said right hand
thread major diameter, said deck screw having a head having means
for engagement by a fastener driving tool, comprising the steps of:
engaging said means for engagement with a fastener driving tool;
rotating said deck screw in a clockwise direction to drive said
deck screw into said board by engagement of said right hand thread
of said lower segment with said board and subsequently with said
base member, thereby forming loose material in said board, said
left hand thread of said upper section evacuating and ejecting at
least a portion of said loose material; and an upper surface of
said board being not substantially deformed when said screw is
driven into said work member and seated in said board.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an plastic composite deck
screw for use with a powered screwdriver to secure a plastic and
composite decking materials to a joist structure.
BACKGROUND OF THE INVENTION
[0002] Plastic deck materials, and plastic composite deck materials
formed from wood products and other fillers mixed with polymer
blends have become popular as an outdoor decking material because
they are durable, and because they often replace treated lumber
that may be treated with environmentally undesirable chemicals such
as arsenic. Composite lumber is an attractive material choice for
decking material because it is substantially rot-free. Composite
lumber is often fabricated from blends of scrap and/or scrap
materials. The materials used include, but are not limited to:
plastic bags, plastic jugs (such as those used for milk and water),
plastic scraps, wood materials such as sawdust and ground-up wood
scraps. Higher quality composite lumber may be constructed of
virgin plastics such as polyethylene, polypropylene, and ground-up
wood scraps. The use of recycled materials adds to the
environmental appeal to the consumer. Examples of such composite
decking materials are Trex.RTM. (registered trademark of Trex
Company, Inc.), Monarch.RTM. (registered trademark of John A.
Biewer Co., Inc.), and TimberTech.RTM. (registered trademark of
Timbertech Limited Limited Partnership). Patents disclosing methods
of fabrication of such materials include U.S. Pat. Nos. 5,088,910,
5,759,680, 5,851,469 and 6,258,876 which are hereby incorporated by
reference. These plastic composite materials are typically formed
into decking materials in the form of planks that are attached to a
joist structure. The joist structure is usually built from wood,
though sometimes the joist structure is built from laminated wood
materials or plastic composite materials.
[0003] The plastic and plastic composite materials have properties
which are different from wood and so typical wood fasteners are not
always suitable to attach the plastic or plastic composite decking
material to the joist structure. Nails are not very suitable as
they may split or crack the decking material. Wood screws can be
used but these require pre-drilling of a hole in the decking
material and joist before the screw can be used. Generally however,
it is too time consuming and uneconomical for a contractor to use
ordinary wood screws to fasten decking to joists so this is not
typically used.
[0004] A "deck screw" is a typical screw used to mount wood deck
boards to underlying joists. A deck screw is a threaded fastener
with a flat head and shank of uniform diameter to which threading
with a steep thread pitch is applied along the lower portion of the
shank. Deck screws are typically driven into deck material with a
power tool without pre-drilling of a hole. However, these
conventional deck screws create problems when used with composite
and all-plastic deck materials. This is the problem known as
"mushrooming." The problem of "mushrooming" is best illustrated in
FIG. 8, which shows a typical deck screw which has been driven into
a plastic composite decking using a power screwdriver. As can be
seen, the material of the decking has deformed, leaving a raised
ring decking material around the head of the screw. The
"mushrooming" effect arises due to the plasticity of the plastic
and composite materials which allows the material to deform from
the heat created by the friction of the screw fastener as it
proceeds into the decking material, combined with the upward
pressure caused by the material displaced by the screw threads and
body as it enters in the decking material. To provide the proper
finished appearance, the "mushroomed" material must be hammered or
punched back into the board by use of the appropriate tool. While
this sometimes is effective, in other instances the appearance of
the hammered-down material is not attractive. Also, striking the
deck surface with a hammer may leave the impression of a hammer
head on the deck. Using a punch to do the job eliminates the hammer
mark problem, but like using a hammer, it is labor intensive.
[0005] Furthermore, because decks using plastic or plastic
composite decking require more floor joists than decks built from
wood, there are a greater number of screws to install. Even a
modest deck requires hundreds of deck screws, making each
additional step very expensive in terms of added labor.
[0006] Several composite decking screw designs have been proposed,
including the screw disclosed in U.S. Pat. No. 6,966,737, and U.S.
Pat. Nos. 6,666,638 and 6,941,635. U.S. Pat. No. 6,966,737
discloses a screw having two thread sections having different
thread pitches and cross-sectional areas, in particular, the shaft
of the screw has a cross-sectional area along a cylindrical
threaded upper section which is greater than the cross-sectional
area along a cylindrical threaded lower section. The disclosed deck
screw is designed to capture loose material cut out from the deck
material and draw it back into the bore as the screw penetrates the
deck material. U.S. Pat. Nos. 6,666,638 and 6,941,635 disclose a
deck screw in which an upper threaded section has a major thread
diameter which is larger than the lower major thread diameter; and
the upper threaded section has a thread angle which is smaller than
the lower thread angle. This deck screw is designed to capture and
pack loose material cut out from the deck material back into the
bore as the screw penetrates the deck material. However, this
design is not effective because the packed material gathers at the
juncture between the deck board and the joist it is being fastened
to. The packed material can prevent proper seating and attachment
of the deck board and can force the deck boards of position. The
packed material can also cause indentations in the deck board and
the joist due to the pressure on the material generated when the
board is fastened to the joist.
SUMMARY OF THE INVENTION
[0007] It is an object of the invention to provide an improved
plastic composite deck screw for securing a workpiece, such as
plastic composite decking, to a base member, such as a floor joist,
which avoids the aforementioned problems.
[0008] It is an object of the invention to provide an improved
plastic composite deck screw which can be used with power tools
such as a power screwdriver or screw gun, without predrilling of a
pilot hole.
[0009] In accordance with one embodiment of the invention, a deck
screw for use with plastic and plastic composite deck materials has
a shank with a lower segment having a right hand thread and an
upper segment having a left hand thread. The upper left hand
threaded section has a major diameter which is the same as or
slightly less than the major diameter of the lower right hand
threaded section. Preferably, the thread angle of the right hand
thread of the lower section is less than the thread angle of the
left hand thread of the upper section and the thread pitch of the
right hand thread of the lower section is greater than the thread
pitch of the left hand thread of the upper section. The deck screw
evacuates and ejects loose material cut out from the deck material
as the screw penetrates the deck material, preventing undesirable
unsightly deformation of the deck upper surface.
[0010] Other objects, aspects and features of the present invention
in addition to those mentioned above will be pointed out in or will
be understood from the following detailed description provided in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a front elevation view of an embodiment of a
plastic composite deck screw in accordance with an embodiment of
the invention;
[0012] FIG. 2 is a cross-sectional view of the upper end and head
of the plastic composite deck screw of FIG. 1, along the line 2-2
of FIG. 3;
[0013] FIG. 3 is a top plan view of the cross-sectional view of the
head of the plastic composite deck screw of FIG. 1;
[0014] FIG. 4 is a detail view of the area 4-4 of the plastic
composite deck screw of FIG. 1;
[0015] FIG. 5 is a detail view of the area 5-5 of the plastic
composite deck screw of FIG. 1;
[0016] FIG. 6 is a front elevation view of the use of the plastic
composite deck screw of FIG. 1 as it is driven into a plastic
composite board material; and
[0017] FIG. 7 is a front elevation view of the plastic composite
deck screw of FIG. 6 after being driven into a plastic composite
board material.
[0018] FIG. 8 is a perspective view of a prior art deck screw after
being drilled into a composite board.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The plastic composite deck screw of the present invention
uses a different design approach than previously used in connection
with composite deck screws. Instead of seeking to trap loose
material formed during drilling of the screw into composite
materials, the screw of the present invention is designed to
evacuate and eject loose material cut out from the deck material as
the screw drills into and penetrates the deck material. The plastic
composite deck screw is provided with a lower section which is
threaded with a self-drilling right hand thread which operates in
the conventional way to drill into and hold in the materials it is
driven into. The plastic composite deck screw is provided with an
upper section which is threaded with a left hand thread which
evacuates and ejects the loose materials formed by the penetration
of the right hand threaded section into the composite material. The
evacuation and ejection is accomplished because the upper left hand
threaded section has a major diameter, and thus a cross-sectional
area, which is the same as or slightly less than the major
diameter, and corresponding cross-sectional area, of the lower
right hand threaded section. In the preferred embodiment of the
invention as shown in the Figures, the major diameter of the
threaded upper section is slightly less (no more than 0.10 mm in
difference) than the major diameter of the threaded lower
section.
[0020] In the plastic composite deck screws deck screws of the
present invention, the thread angle of the right hand thread of the
lower section is less than the thread angle of the left hand thread
of the upper section. The thread pitch of the right hand thread of
the lower section is greater than the thread pitch of the left hand
thread of the upper section.
[0021] Referring now to FIGS. 1-7, where like numerals indicate
like elements in the drawings, an plastic composite deck screw 10
in accordance with one embodiment of the invention is shown.
Plastic composite deck screw 10 comprises a shank 20 and a head
50.
[0022] Shank 20 has a lower segment 22 and an upper segment 24.
Lower segment 22 is threaded with a right hand thread 26. Upper
segment 24 is threaded with a left hand thread 28. Threads 26 and
28 of the lower segment 22 and an upper segment 24 are preferably
located adjacent each other without any axial gap between them.
Most preferably, threads 26 and 28 are conjoined in a continuous
thread pattern as shown at 29 in order to slice away extruded
material formed during drilling the screw into a deck material.
[0023] The tip end 46 of the shank 20 is preferably provided with a
self-drilling tip, most preferably, a Type 17 self-drilling point
48. The self-drilling point preferably has a lead thread 47 at the
bottom of the point in order to start self-drilling of the screw
when used in harder materials.
[0024] The threaded lower segment 22 of the plastic composite deck
screw 10 comprises from about 45 percent to about 80 percent of the
length of the threaded portions of shank 20, and more preferably,
it is between about 60 percent to about 70 percent of the length of
the threaded portions of the shank 20. In the most preferred
embodiment, the threaded lower segment 22 comprises about
two-thirds of the length of the threaded portions of shank 20. The
threaded upper segment 24 of the plastic composite deck screw 10
comprises from about 20 percent to about 65 percent of the length
of the threaded portions of shank 20, and more preferably, it is
between about 30 percent to about 40 percent of the length of the
threaded portions of shank 20. In the most preferred embodiment,
the threaded upper segment 24 comprises about one-third of the
length of the threaded portions of shank 20. Thus for a screw in
the range of 70 mm in length, the length of the threaded upper
segment 24 will be between 15-17 mm and the length of the threaded
lower segment 22 will be between 43-46 mm.
[0025] Thread 26 on lower section 22 has a major diameter D.sub.1,
thread 28 on upper section 24 has a major diameter D.sub.2. D.sub.2
must never be greater than D.sub.1. D.sub.2 may be equal to
D.sub.1, however, the best results are obtained when D.sub.2 is
slightly less than D.sub.1. In this application, the definition
"slightly less" as used in describing the relationship between
D.sub.2 and D.sub.1 means that there is no more than 0.5 mm in
difference between D.sub.2 and D.sub.1, and preferably, no more
than 0.25 mm in difference between D.sub.2 and D.sub.1, and most
preferably, no more than 0.10 mm in difference between D.sub.2 and
D.sub.1.
[0026] As noted above, the function of the thread 28 is to evacuate
and eject the loose materials formed by the penetration of the
right hand threaded section into the composite material. The major
diameter D.sub.2 of thread 28 is selected to pack as little
material as possible. This is in sharp contrast to prior art screws
which used the upper thread to pack material into the penetration.
Thus the major diameter D.sub.2 of thread 28 should be no larger
than the major diameter D.sub.1 of thread 26, and of the same or
slightly smaller size. If D.sub.2 is significantly less than
D.sub.1 the upper section 24 will not be effective in evacuating
and ejecting loose material formed during driving of the screw, so
close attention to these tolerances are required.
[0027] Referring now particularly to FIGS. 4 and 5, the thread
angle A.sub.1 of the right hand thread 26 of the lower section 22
is less than the thread angle A.sub.2 of the left hand thread 28 of
the upper section 24. In one preferred embodiment of the invention,
the thread angle A.sub.1 of the right hand thread 26 of the lower
section 22 is between about 25.degree. to about 40.degree., most
preferably 30.degree., and the thread angle A.sub.2 of the left
hand thread 28 of the upper section 24 is between about 30.degree.
to about 45.degree., most preferably 40.degree.. The use of a
higher thread angle A.sub.2 for the left hand thread 28 of the
upper section 24 improves the evacuation of material in the
area.
[0028] Again, with reference to FIGS. 4 and 5, the thread pitch
X.sub.1, which is the distance between threads for the right hand
thread 26 of the lower section 22 is greater than X.sub.2, which is
the distance between threads for the left hand thread 28 of the
upper section 24. In the preferred embodiment of the invention, the
thread pitch of the right hand thread 26 of the lower section 22 is
between about 2.3 mm to about 3.2 mm, most preferably, about 2.8
mm, and the thread pitch of the left hand thread 28 of the upper
section 24 is between about 1.8 mm to about 2.8 mm, most preferably
about 2.3 mm.
[0029] Head 50 of deck screw 10 includes an upper surface 58 having
a means for engagement 52 by a fastener driving tool such as a
power screwdriver, screw gun, or drill with appropriate bit. The
means for engagement 52 can comprise a Robertson square recess as
shown in the figures, or a hexagonal recess, a Phillips head
recess, a TORX.RTM. recess, or it may comprise any other head
designs, including straight slot recess, hexagonal head, square
head, etc. Head 50 further is provided with an annular channel 54
on the lower surface 56 of head 50 surrounding the shank 20.
[0030] The plastic composite deck screw 10 is preferably formed of
steel wire by conventional cold forming processes, and it may be
anodized or plated as desired with appropriate protective
coatings.
[0031] The use of plastic composite deck screw 10 is shown in FIGS.
6 and 7. When the plastic composite deck screw 10 is rotated by a
power tool, the lower section 22 self-drills into the deck material
62, and continues on into joist 60. In this process, a small amount
of deformation 64 is caused in the upper surface of the deck
material 62 around the shaft 20 of deck screw 10. As the deck screw
10 continues to drill down, the upper section 24 of the deck screw
enters into the deck material 62 and subsequently into the joist
60. Upper section 24 captures and ejects loose material 63 formed
by the passage of lower section 22 through deck material 62,
releasing the upward pressure causing the deformation 64. As this
pressure is relieved, the head of screw 10 is able to be drawn down
with counterboring or countersinking into the deck material 62
until the head 50 is seated flush into the board 62, leaving a
finished deck material 62 with an upper surface 68 which is not
substantially deformed, and an installed deck screw 10 with an
upper surface 58 which is substantially flush with the upper
surface 68 of the deck material 62. The "mushroom" effect caused by
prior art screws which is illustrated in FIG. 8 is eliminated. A
small ring 66 of loose material 63 surrounds head 50 and is easily
swept away.
[0032] The effectiveness of my new deck screw design is the result
of a group of elements which work in combination to provide an
effective deck screw for use with plastic and plastic composite
materials.
[0033] It is to be appreciated that the foregoing is illustrative
and not limiting of the invention, and that various changes and
modifications to the preferred embodiments described above will be
apparent to those skilled in the art. Such changes and
modifications can be made without departing from the spirit and
scope of the present invention, and it is therefore intended that
such changes and modifications be covered by the following
claims.
* * * * *