Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF TIIE INVENTION
This invention relates to splines that are inserted into
grooves. More particularly, this invention relates to splines that
are inserted into longitudinal grooves in wooden members to hide
and protect conduit recessed therein. (As used herein, the term
"conduit" means any wire, pipe, tube, rope, rod,or the like, for
example, electrical wire, pneumatic tubing, water pipes~ or control
rods, that may be recessed in such grooves~.
It is often desirable to hide conduit inside members, such
a~, poles, for aesthetic and protective reasons. For example, in
geographic areas where electricity is carried by underground
cables rather than by overhead lines, outdoor lamp posts sometimes
are hollow, metal poles having the electrical supply lines to the
fixtures inside. In many areas wooden poles are used for reasons
of economy. Since it is economically impractical to drill an
internal passageway for the wires in wood poles measuring twenty-
five feet or more, external longitudinal grooves have been used.
The groove is cut along the outer surface of the pole and the
electrical supply wires are recessed therein.
A continuing problem, however, has been how to seal the
mouth of the groove (the cut in the periphery or circumference of
the pole) in an aesthetically pleasing way and still protect the
wires in the groove over a period of time. Complicating this
pxoblem is the natural tendency of wood to expand and contract,
thereby changing the size and shape of the groove. Such expan-
sion and contraction are caused by changes in the woodls moisture
content due to environmental conditions, particularly, the weather
U.S. Patent No. 1,972,187 ~th? '18~ patent) discloses
forming a longitudinal dove-tailed groove in a wooden lamp post,
recessing electrical lines th~reîn and sealing the groove with two
strips of wood that form a dove-tailed wedge and are held in place
by screws. No adhesive is used.
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U.S. Patent No. 3,360,601 (the '601 patent) discloses a
; groove in a wooden light pol~, which groove has a rectangular or
triangular cross-section. The electrical supply wires to the
fixture are recessed in the groove, and the rectangular groove
is "closed by a suitable plugstrip," the nature of which is not
disclosed. The triangular groove is sealed by reinserting the
triangular strip cut out to form the groove. Adhesive is used
on both internal faces of the triangular (wedge-shaped) strip to
secure it in place.
' U.S. Patent No. 3,562,403 (the '403 patent) discloses
forming two longitudinal grooves in a wooden utility pole and
recessing electrical wires in one of the grooves. The stated
purpose of the other groove is to relieve internal stress. The
groove containing the wires is capped by a wood putty filler, and
several layers of polyester resin and glass fiber are applied
around the exterior of the pole. Optionally, the pole is wrapped
with cellophane or paper before the resin-fiber mixture is applied.
Neither the '187 nor the '601 patent re~ognizes the
~' problem of groove expansion. Such expansion may result in loss
of the spline inserted in the groove or decrease in the protection
of the hidden wire, or both. In any event, any crack formed be-
tween the spline and the side o~the groove makes the pole un-
sightly. The '403 patent, while not referring specifically to
groove expansion, acknowledges the related problems of checking
and splitting. To overcome them, the '403 patent discloses that
the poles should be encased in plasticg with optional cellophane --
or paper wrapping thereunder; however, this substantially in-
~ creases the cos~ and complexity o such poles.
; ' Thus, these patents fail to disclose aesthetically
pleasing, easily installed, relatively inexpensive, and durable
splines for protecting hidden conduit recessed in a groove in a
member subject to aircumferential expansion and contraction.
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SUMM~RY
It has now been discovered that conduit recessed in a
longitudinal groove in a member subject to circumferential ex-
pansion can be protected from the weather in a relatively i~expen-
sive, aesthetically pleasing manner. This is accomplished by
employing a spline comprising an outer face portion and an in~
sertion portion. The spline i~ attached to the member on only
one side of the groove.
The cross-section of the preferred spline is "T"- or
mushroom-shaped. The outer face of the spline, the top of the "T",
is wider than the mouth of the groove, which allows the spline to
continue to cover the groove ~and hide and protect the conduit
recessed therein) even when the groove becomes wicler ~ue to
natural circumferential expansion of the pole.
BRIEF DESCRIPTION OF T~E DRAWINGS
In order to more fully describe the present invention,
reference will be made to the accompanying drawings in which:
Figure 1 is a view of an outdoor lighting pole;
~ igure 2 is an enlarged cross-sectional view oE the pole
taken along line 2-2 of Figure l;
Figure 3 is an enlarged view of a portion of Figure ~;
~ igure 4 is an exploded view of Figure 3;
Figure 5 is a cross-sectional view of the pole and spline
of Figures 1 to 4 after the pole has cracked and the groove thereby
widened;
Figure 6 is a cross-sectional view showing another spline
of this invention;
Figure 7 is a cross-sectional view illustrating a key~ol~-
shaped groove;
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Figure 8 is a cross~sectional view of a pole and spline
in which the electrical wires are contained as a uni-t within the
insertion piece of the spline;
Figure 9 is a cro~s sectional v:iew of a pole and a spline
in which the wires are contained within a groove in the insertion
plece;
Figure 10 is a cross-sec-tional view of a pole in combina-
tion with an irregularly-shaped spline;
Figure 11 is a cross~sectional view of a pole and a
truncated triangularly-shaped spline; and
Figure 12 is a cross-sectional view of a spline inserted
in a pole having a rectangular cross-s~ction.
DETAILED DESCRIPTION OF THE INVENTION
The spline of this invention may be used in any member
subject to circumferential expansion and contraction having a
longitudinal groo~e. Such members may be of any size or shape.
For example, if the member is an outdoor lighting pole, its cross-
; sectional shape may be rectangular, circular, or triangular, the
length may be from just a few feet up to 25 feet or more, and
the cross-sectional area may be from a few square inches to several
sguare feet or more. Usually, the member is an outdoor lighting
pole having a circular cross~sectional area.
The long~tudinal groove in the member is as long as
circumstances require. For example, the groove in an outdoor lamp
post haviny a fixture at its top would require a groove running the
length of the pole. The depth and width of the groove must be
sufficient to accommodate the insertion piece of -the spline~ Addi-
tionally, if the conduit to be recessed in the groove is not part
of the insertion piece of the spline, then the groove must be
large enough ko contain it as well as the insertion piece.
Generally, the groo~e will be from 0.5 to 5 inches deep, prefer-
ably from 0.5 to 2 inches deep. The width may range from O.l to
2 inches, preferably from O.l to 1 inches.
Techniques for making the groove are well-known. ~ny
wood-working tool that can cut a groove along the pole may be
used. For example, a standard circular saw blade,with the cutting
edge appropriately modified, mounted in a portable or jig-type
p~wer head could be used.
The spline is roughly "T"-shaped in cross-section. It
can also be described as mushroom-shaped in cross-section. The
spline may be viewed as comprising two sections. The outer face
o the spline is the section that is visible after the spline has
been installed. The outer face is analogous to the top of the "T"
or the cap of the mushroom. The insertion piece of the spline is
the portion that is inserted into the groove in the longitudinal
member~ It is analogous to the base of the "T" or the stem of the
mushroom.
The spline may be manufactured using any known techni~ue,
such as, extrusion. The two portions of the spline may be made
separately and later joined or the spline may be made as a unit~
The spline may be made in standard lengths or in long segments
that could, for example, be wound on a spool.
~0 The spline may be composed of any material that is
chemioally inert, has good outdoor aging characteristics, excellent
electrical properties (for example, high resistivity), good abra- ,
sion resistance, and is hard, tough, light weight, and noninflam-
able.Generally, a plastic is used but other materials (e,g.,
metals or wood) may be used dependi~g on the particular service.
Preferably, the spline is compDsea of polyvinylchloride and is
~lexible. Cellulose b~utyrate may also b~ used~
The outer face of the spline is usually from 0.01 to 0.5
inches thick, preferably from 0.01 to 0.25 inches thick. The
outer face need not be of uniform thickness~ For example, the
ends of the ou~er ~ace may be of one thickn~ss and gradual:Ly
increase to a maximum thickness at the point where the outer face
; meets the insertion piece9
The outer Eace may be of any sh~pe. It is desirable,
however, that the shape not prevent the outer face oE the spline
from lying against the pèriphery of the member. This is for
aesthetic reasons as well as to prevent water ~rain, sleet, and
so forth) from entering the groove. Thus, if the spline is being
inserted into a member having a circular cross-section, the outer
face of the spline will generally have approximately the same
curvature as the member so that the outer face may lie flush
against the memberO If the spline is being used on a flat surface
10. of a member, the outer face will generally also be flat, for the
same reason.
The width of the outer face must be greater than the
width of the grooveO It is a feature of this invention that as
the sides of the groove move farther apart, due to the natural
circumerential movement of the member, the mouth of the groove
remains hidden by the outer face of the spline. Thus, the spline-
and-pole unit will remain aesthetically pleasing and the conduit
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will be protected even khough the groove enlarges. In contrast,
the splines of the prior. a~ do not cover the mouth of the groove. ~:
Thus, watar can enter the mouth of the groove and promoke cracking.
The insertion piece may be o any shape so long as it
possesses a suitable surface for bonding to one of the faces of
the groove, assuming adhesive is to be.used to attach the in-
sertion piece to the member. In that case, if the groove is sub-
stantially triangular in cross-sec~ion, the insertion piece will
also have at least one side forming a corresponding angle with
the outer face, and usually a triangular insertion piece ~ill be
used. If the groove i5 substantially rectangular, the i~sertion
piece will also be generally rectangular. Naturally, the spline
; 30 need not touch the back wall of the groove or conform to the shape
of the back portion of khe groove. For example, a rectangular
insertion piec~ can be used with a keyhole-shaped groove. The
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insertion piece need not be solid and, in fact, the conduit may becompletely encased within the insertion piece.
Generally, the insertion piece meets the outer face mid-
way between the two edges of the outer face. Howeverl the inser-
tion piece may also meet the outer face at other points~ For
example, the insertion piece could meet the outer face near one
of the tw~ edges of the outer face, in which case the cross-section
o~ the spline would resemble an "L".
A~other essential feature of the present invention is
that the spline is attached to the member on only one side of the
groove. If the spline were attached to the member on both sides
of the groove, circ'umferential expansion of the member and con-
sequential widening of the groove would cause failure of the
spline, of the means for attaching the spline to the member, or
of both. For example, if adhesive were used on both sides of the ~'
~ groove and the groove widened, the spllne might not remain ad-
'~ hered to the same side of the groove along the entire length of
the member. In that case, the spline would appear to snake along
the member. It is also possible that the spline could fall out
2'0 of the member. By attaching the spline to the member~on only ~ne
of the two sides of the groove, the possibility of such tensive
forces is eliminated.
' Any means may be used to attach the spline to the member
and the point of attachment may vary. E'or exa~ple, nails, staples,
or the like may be used without ~dhesive to attach the outer face
to the periphery of the member. A'lternatively, adhesive may be
usea between the insertion piece a~d the corresponding inner
surface of the groove and one side of the outer face nailed to the
; periphery of the member. Another possibility is that adhesive
alon~ is used, between the insertion piece and the inner surface
of the groove, between the member and the outer face of the spline,
or in both places. Preferably, the attaching means is aclhesive and
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it is used both between the member and the outer face and between
the insertion piece and the inner surface of the groove. In any
case, it is essential that the spline be attached to the member
on only one side of groove.
The procedure for installing the spline is as follows.
First the groove is formed using any suitable technique. Then,
if the conduit is separate from the spline, the conduit is placed
into the groove. Adhesive, staples, or the like may be used to
secure the conduit in the groove. If adhesive is to be used to
attach the spline to the member, the adhesive is applied to the
member on one side of the groove or to the spline or to both and `
the insertion piece is inserted into the groove. If means such
as staples are to be used, the spline is inserted and the outer
face stapled to the member.
If adhesive is used it should be weather-resistant.
Desirably, the adhesive should be able to withstand direct weathering
for approximately 7 years or more. Because the mem~er may expand
and contract at or near the side of the groove to which the spline
is adhered, the adhesive must possess sufficient dry elasticity
to prevent such expansion and contraction from breaking that ad-
hesive bond. Thus, desirably, the adhesive should have 300% to
500% shrink and stretch capability. Also, the adhesive should
cure sufficiently in a relatively short period of time to allow
handling. Such curing should not be affected by compounds normally
present in the member. For a wood member these compounds include
water, wood oils and resins, and preservatives. Additionally, the
compounds present should have minimal effect on the properties
of the cured adhesive.
A preferred group of adhesives is tha-t disclosed
in United States Patent No. 3,372,083. These adhesives
are made from an isocyanate-terminated prepolymer and
an isocyanate adduct of an unmodified tar. The
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prepolymer is a polyurethane-type made from polyols and isocyanates
having at least two reactive isocyanato yroups. The adduct is made
by reacting a bituminous substance with an isocyanate having one or
more reactive isocyanato groups. Vulchem 116 adhesive, manufactured
by Mameco International of Cleveland, Ohio ~nd which, according to
Mameco, is covered by the aforesaid patent, ha,s been found es-
pecially useful.
Turning now to the Figures, Fig. 1 depicts an outdoor
street light 10 employing the present invention. The street light
10 comprises wooden member 12, spline 30, and fixture 14.
Figure 2 is a cross-sectional view of wooden member 12 `
and spline 30 taken along line 2-2 of Fig. 1. A longitucLinal,
rectangular shaped groove in wooden member 12 is defined by left-
side wall 16, ri~ht-side wall 18, and rear wall 20. Wire 4~ is
recessed in the groove and is hidden from view by spline 10, which
has the preferred "T"-shaped cross-section.
In Figure 3, an enlarged view of the area surrounding
spline 30, it is seen that adhesive layer 22 bonds wire 40 and
spline 30 to the member. The outer face of the spline is bonded
to the periphery of the member and the insertion piece and wire are
bonded to the left inner surface of the groove. Thus, the spline is
attached to the member on the left side of the groove by means of
'IL" shaped glue line 22. Spline 30 is fully inserted into the
gxoove so that the outer face lies against the periphery (or cir-
cumference) of member 12.
Figure 4 is an exploded view of Fig. 3. Wire 40 actually
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contains three wires 42. Insertion piece 34 and outer face 32 are
seen to comprise spline 30.
Figure 5 is a view of Fig. 2 later in time after a
~ 30 longitudinal crack has developed in w~oden member 12. Right
; gxoove wall 18 has moved away from wire 40 and insertion piece 34.
~ However, this crack is not visible from the outside because outer
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face 32 o~ spline 30 is wide enough to hide the crack, Further-
more, outer face 32 has remained in close contact with the periphery
of wooden member 12, thus pro~ecting wire 40 from environmental
factors, such as, the weather.
In Figure 6, walls 116, 118, and 120 define a longitudinal,
rectangular groove in member 112. A layer of adhesive 122 secures
wire 140 and spline 130 to the member on the left side of the
groo~e. Spline 130 comprises outer face 132 and insertion piece
134. In this case, spline 130 has been fabricated such that in-
sertion piece 134 meets outer face 132 near one edge of the outer
face. Such an asymmetrical spline may be used, for example, when
it is anticipated that the groove expansion will occur primarily
on one side of the groove. Here, expansion is expected primarily
on the side of wall 118.
In Figure 7, member 212 contains a keyhole-shaped yroove
defined by left wall 216, right wall 218, and rear circular wall
220. Wire 240 is recessed in the circular portion 220 of the
groove. Spline 230 is attached to the member on the left side of
*he groove by means of nails 236. Outer face 232 lies against the
perimeter of member 212.
In Figure 8, walls 316, 318, and 320 define a rectangular
groove in member 312. Wires 342 are contained within insertion
piece 334 of spline 330~ Adhesive layer 322 bonds insertion
piece 334 to wall 316 of the groove and outer face 332 lies
against the periphery of member 312. There is no adhesive be-
tween the outer face of the spline and the memberO
In Figure 9, walls 416, 418, and 420 define a rectangular
groove in member 412. Spline 430 compris~s outer face 432 and
insertion piece 434. The insertion piec~ is open at the back and
~30 wires 442 have been recessed thexein. A layer of adhesive 422
bonds the spline to the member on the left side of the groove.
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In Fi~ure 10, walls 516, 518, and 520 define a rectangular
groove in member 512. Spline 530 comprises outer face 532 and
insertion piece 534. The as~mmetrical insertion piece 534 com-
prises a triangular portion and a rectangular portion and is
bonded to wall 516 by glue line 522. Wires 542 lie in the space
between insertion piece 534 and right wall 518.
In Figure 11, walls 616 and 618 define a triangular
groove in member 612. Wires 6g2 are recessed at the back of the
groove and are held in place by spline 630. Spline 630 comprises
outer face 632 and insertion piece 634, the latter having a
truncated triangular ~or trapezoidal) shape. A layer of adhesive
622 bonds insertion piece 634 to wall 616. Note that the left
side of insertion piece 634 conforms to wall 616. It is not
necessary that the right side of insertion piece 634 conform to
wall 618 because they are not being adhesively joined.
In Figure 12, member 712 having a rectangular cross-
section is shown. Walls 716, 718, and 720 define a groove into
which wires 742 and spline 730 are inserted. Adhesive layer i22
bonds insertion piece 734 to wall 716. Outer face~732 of spline
730 is flat rather than curved so that it can lie flush against
the outer wall of the member. Wires 742 are not glued or other-
wise bonded in place, but are held in place by the spline.
It should be understood that -the various embodiments
shown in the figures are fox illustrative purposes only. Other
modifications and variations will be apparent to those skilled in
the art and the claims are intended to cover all such modifications
and variations.
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