Fixture and method for fixing a plurality of plates

A decking plate is arranged on a cover plate over the open top of a U shaped channel, such that a through hole of the decking plate is positioned aligned over a cutout portion of the cover plate. A fixture is inserted through the through hole and the cutout portion. The fixture includes a head, a screw, a tube like portion and a protrusion. The cover plate and the decking plate are pinched and fixed together between the head and the protrusion of the feature. Thus, a positioned displacement of a attached plurality of plates can be prevented.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to fixtures and methods for fixing a 
plurality of plates, and more specifically, to a fixture and a method for 
fixing a plurality of plates each having a through hole in a stack. 
2. Description of the Background Art 
Conventionally, a U shaped groove, trough or channel 3 shown in FIG. 6 has 
been widely known for example as a drainage channel. A cover or a lid 2 is 
generally placed on the to of the U shaped groove or channel 3. When such 
a U shaped groove or channel 3 is arranged for example on a construction 
site, and vehicles are intended to pass thereover, a decking 1 is 
preferably placed on cover 2 for protection, as shown in FIG. 6. The 
provision of decking 1 ensures safety as a vehicle passes over U shaped 
groove 3. 
However, as shown in FIG. 6, the above mentioned, decking 1 is often 
displaced from its proper position on cover 2 because it is simply placed 
loosely onto cover 2. Thus, decking 1 cannot fully exhibit its function of 
protecting cover 2. In addition, when decking 1 is made for example of 
resin and light in weight, it may possibly be lifted or taken away. 
SUMMARY OF THE INVENTION 
The present invention is made to solve the aforementioned problem. An 
object of the present invention is to provide a fixture and a method for 
fixing a plurality of plates, so as to achieve full protection for a plate 
such as a cover for an by U shaped groove or channel and so as to reduce 
the possibility of lifting of the plates. 
The fixture for a plurality of plates according to the present invention 
fixes, onto a first plate having a first through hole, a second plate 
having a second through hole stacked on said first plate. The fixture 
includes a head, a screw, a tube like portion and a protrusion. The screw 
downwardly extends from the head and has a male screw threading on its 
outer surface. The tube like portion is provided with a female screw 
threading on its inner surface and the screw is received therein. The 
protrusion outwardly protrudes from the outer surface of the tube like 
portion. The fixture having the above mentioned structure pinches and 
fixes the first and second plates between the head and the protrusion, 
with the screw inserted into the first and second through holes. It is 
noted that the above mentioned first and second through holes encompass 
cutout portions which are provided at the ends of the first and second 
plates and pass therethrough in a direction of thickness. 
As described above, the fixture for a plurality of plates according to the 
present invention includes the head and the protrusion, and fixes and 
pinches the first and second plates therebetween. Thus, positioned 
displacement of the second plate on the first plate is prevented, so that 
the second plate can provide full protection for the first plate. In 
addition, if the first and second plates are fixed together using the 
above mentioned fixture, the first and second plates connected to each 
other are not easily carried away even if the plates are not secured to 
the U shaped channel, for example when the first plate is made of concrete 
and heavy in weight. Further, by connecting fixtures together, a number of 
first and second plates are connected, so that they are not easily carried 
away. This may serve as a theft deterrent. 
The above mentioned first and second through holes preferably have a first 
opening width and a second opening width which is smaller than the first 
opening width. Then, a sum of a protrusion length of the protrusion and a 
width of the tube like portion (a length corresponding to L1 in FIG. 3) is 
set smaller than the first opening width and larger than the second 
opening width. Here, the width of the tube like portion is determined 
adjacent to the protrusion, and corresponds to the width at the portion 
between protrusions 4d in FIG. 3. 
As mentioned above, by setting the sum of the protrusion length of the 
protrusion and the width of the tube like portion to be smaller than the 
first opening width, the screw with a tube like portion received thereon 
can be inserted into the first and second through holes from above so that 
the protrusion is positioned under the first plate. Thus, as the screw 
with the tube like portion received thereon needs only to be inserted into 
the first and second through holes from above, the insertion is 
accomplished quite easily. Thereafter, by rotating the protrusion, the 
protrusion can be positioned immediately below a portion of the first 
plate defining the second opening width of the first through hole. Then, 
the screw is rotated about its axis and moved in a direction in which the 
head comes closer to the protrusion with the protrusion abutting against 
the bottom surface of the first plate, so that the first and second plates 
are pinched between the bottom surface of the head and the upper surface 
of the protrusion. Thus, the first and second plates are fixed together 
simply by rotating the protrusion and the screw after inserting the screw 
with the tube like portion received thereon into the first and second 
through holes. Accordingly, the fixing operation for the first and second 
plates is extremely facilitated. 
In a method of fixing a plurality of plates according to the present 
invention, a second plate having a second through hole is stacked and 
fixed on a first plate having a first through hole for which the following 
fixture is used. The fixture includes a head, a screw downwardly extending 
from the head and having a male screw threading formed on its outer 
surface, a tube like portion having a female screw threading on its inner 
surface and receiving the screw, and a protrusion outwardly protruding 
from the outer surface of the tube like portion. The method of fixing a 
plurality of plates according to the present invention includes the 
following steps. The second plate is placed on the first plate such that 
the second through hole is positioned on the first through hole. By 
inserting the screw with the tube like portion received thereon into the 
first and second through holes from above, the protrusion is arranged 
below the first plate. The first and second plates are pinched and fixed 
between the protrusion and the head by rotating the protrusion and the 
screw. It is noted that the above mentioned first and second through holes 
have a first opening width allowing passage of the protrusion 
therethrough, and a second opening width which is smaller than the first 
opening width, i.e. each of the through holes has an elongated or slotted 
hole shape that is longer than it is wide. 
As in the foregoing, in the method of fixing a plurality of plates 
according to the present invention, by inserting the screw with the tube 
like portion received thereon into the first and second through holes from 
the position above the second plate, the protrusion is arranged below the 
first plate. As the screw with the tube like portion received thereon 
needs only to be inserted into the first and second through holes from the 
position above the second plate, the screw can be extremely readily 
inserted. It is noted that the inserting operation is made possible by the 
fact that the first and second through holes have the first opening width 
which allows passage of the protrusion therethrough. Subsequent to the 
insertion, the protrusion and the screw are rotated. The rotation of the 
protrusion is readily achieved, for example simply by manually rotating 
the screw about its axis. The rotation of the protrusion enables 
engagement between the protrusion and the first plate. This is because the 
first through hole has the second opening width which is smaller than the 
first opening width. The rotation of the screw by itself is accomplished 
for example simply by rotating the screw along with the head, while 
preventing rotation of the protrusion by abutting the upper surface of the 
protrusion against the back surface of the first plate. Thus, the screw is 
readily rotated by itself. By rotating the screw along with the head while 
preventing rotation of the protrusion, the head can be moved in a 
direction which comes closer to the tube like portion. Thus, the first and 
second plates can be pinched and fixed between the head and the 
protrusion. 
The foregoing and other objects, features, aspects and advantages of the 
present invention will become more apparent from the following detailed 
description of the present invention when taken in conjunction with the 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An embodiment of the present invention will now be described with reference 
to FIGS. 1 to 5. FIG. 1 is a partially sectional perspective view showing 
a cover 2 and a decking 1 for a U shaped groove or channel 3, which have 
been fixed using a fixture 4 according to the present invention. FIG. 2 is 
a cross sectional view showing an enlarged detail of the structure shown 
in FIG. 1. Note that the decking 1 is fixed to cover 2 by the fixture 4, 
but the cover 2 is not secured to the U shaped channel 3 but rather simply 
placed loosely thereon. 
Referring first to FIG. 1, cover 2 made of concrete has, at its one end, a 
cutout portion 2a passing through cover 2 in a direction of thickness. 
Cutout portion 2a has a first opening width W1 and a second opening width 
W2 which is smaller than first opening width W1. Placed on cover 2 is a 
decking 1, which is made of resin. Decking 1 has a through hole 1a in its 
middle portion. Through hole 1a has a first opening width W3 and a second 
opening width W4 which is smaller than the first opening width W3. 
As shown in FIG. 1, decking 1 is placed on cover 2 such that through hole 
1a is positioned on cutout portion 2a. Fixture 4 is mounted to extend from 
through hole 1a to cutout portion 2a. Fixture 4 includes a head 4a having 
a generally disk-like shape, a screw 4b extending downwardly from head 4a 
and having a male screw threading on its outer surface, a tube like 
portion 4c having a female screw threading on its inner surface and 
receiving screw 4b, and a protrusion 4d outwardly protruding from the 
outer surface of tube like portion 4c. 
As shown in FIG. 2, by pinching cover 2 and decking 1 between head 4a and 
protrusion 4d, cover 2 and decking 1 are fixed to each other. Thus, 
decking 1 cannot be displaced from cover 2, thereby ensuring that decking 
1 provides protection for cover 2. As a result, safety when a vehicle or 
the like passes over cover 2 is improved. It is noted that a concave 
portion (not shown) for receiving protrusion 4d may be provided on the 
back surface of cover 2. This prevents rotation of protrusion 4d while 
mounting fixture 4 or after cover 2 and decking 1 are fixed together. 
Therefore, efficient mounting operation for fixture 4 as well as 
improvement in reliability after cover 2 and decking 1 are fixed together 
are achieved. 
Referring now to FIG. 3, the structure of fixture 4 will be described in 
detail. A pair of holes 5 are formed in head 4a. Holes 5 are formed for 
rotating screw 4b along with head 4a. Holes 5 may or may not pass through 
head 4a. The provision of holes 5 allows rotation of screw 4b along with 
head 4a using a jig having for example a pair of convex portions which can 
be fit into holes 5. Thus, rotation of screw 4b is accomplished both 
readily and efficiently. It is noted that a concave or convex element 
other than the above mentioned holes 5 may be provided for head 4a, as 
long as it is useful for rotation of head 4a. 
Diameter D of head 4a is set larger than second opening widths W2 and W4. 
Thus, the bottom surface of head 4a and the upper surface of decking 1 are 
made engageable. It is noted that, while a planar shape of head 4a shown 
for example in FIG. 3 is round, it may have any other shape, such as a 
triangle or a square. 
The above mentioned head 4a and screw 4b are integrated together, with 
screw 4b having a straight shape. Tube like portion 4c receiving screw 4b 
extending therethrough has a cylindrical shape. Tube like portion 4c can, 
however, have a shape other than the cylindrical shape. For example, it 
may be a square pole. A pair of protrusions 4d are formed outwardly 
protruding from the outer surface of tube like portion 4c. The pair of 
protrusions 4d extend in opposite directions in the example shown in FIG. 
3. 
A sum L1 of the protrusion length of the above mentioned pair of 
protrusions 4d and the width of tube like portion 4c in a portion which is 
adjacent to protrusion 4d is set smaller than first opening width W1 or W3 
and larger than second opening width W2 or W4. In addition, a maximum 
value of the width for tube like portion 4c and a width L2 of protrusion 
4d are set smaller than second opening widths W2 and W4. As the above 
mentioned sum L1 and width L2 are respectively smaller than first opening 
width W1 or W3 and second opening width W2 or W4, screw 4b with tube like 
portion 4c screwed thereon can be inserted into and through first through 
hole 1a and cutout portion 2a. Further, as the above mentioned sum L1 is 
larger than second opening width W2, protrusion 4d can be rotated and 
engaged with cover 2. Thus, cover 2 and decking 1 are pinched between head 
4a and protrusion 4d. 
At this time, as shown in FIG. 3, if protrusion 4d extends in a direction 
which is orthogonal to the axial direction of tube like portion 4c and has 
a planar upper surface, contact area between protrusion 4d and the back 
surface of cover 2 can be increased. Thus, rotation of protrusion 4d while 
mounting fixture 4 is effectively prevented, so that cover 2 is tightly 
fixed against decking 1 by fixture 4. It is noted that the upper surface 
of protrusion 4d can be provided with fine irregularities for preventing 
its rotation with respect to the back surface of cover 2. When the back 
surface of cover 2 is structured as a horizontal plane as shown for 
example in FIG. 2, protrusion 4d can extend in the direction which is 
orthogonal to the axial direction of tube like portion 4c as mentioned 
above. On the other hand, when the back surface of cover 2 is structured 
as an inclined plane or the like, it is preferable to extend protrusion 4d 
along the back surface of cover 2 or to form the upper surface of 
protrusion 4d in a shape which fits the shape of the back surface of cover 
2. Thus, the contact area between the upper surface of protrusion 4d and 
the back surface of cover 2 can surely be increased. 
With reference now to FIGS. 4 and 5, a method of fixing a plurality of 
plates using a fixture 4 according to the present invention will be 
described. FIGS. 4 and 5 are partially sectional perspective views showing 
characteristic first and second steps of the method of fixing a plurality 
of plates according to the present invention. 
Referring to FIG. 4, a decking 1 is placed on a cover 2 such that a through 
hole 1a is positioned on a cutout portion 2a. Then, fixture 4 is inserted 
into through hole 1a and cutout portion 2a from above decking 1. More 
specifically, a screw 4b with a tube like portion 4c screwed thereon is 
inserted into and through the through hole 1a and cutout portion 2a from 
the side of protrusion 4d. The inserting operation can be extremely 
readily accomplished as fixture 4 needs only be inserted into through hole 
1a and cutout portion 2a from above decking 1. 
Referring now to FIG. 5, by inserting screw 4b into through hole 1a and 
cutout portion 2a, protrusion 4d is arranged below the bottom surface of 
cover 2. Thereafter, protrusion 4d is rotated in a direction indicated by 
an arrow shown in FIG. 5. Rotation of protrusion 4d can be readily 
achieved for example by manually rotating screw 4b along with head 4a. 
Alternatively, only protrusion 4d may be rotated below cover 2 using a jig 
such as a bar. 
Then, screw 4b is rotated along with head 4a in the direction indicated by 
the arrow shown in FIG. 5. At this time, screw 4b can be rotated while 
forcing the upper surface of protrusion 4d against the bottom surface of 
cover 2 so as to prevent rotation of protrusion 4d. Screw 4b may also be 
rotated while preventing rotation of protrusion 4d using the above 
mentioned jig such as a bar. The aforementioned specific jig is preferably 
used for rotating screw 4b. By rotating screw 4b using such a jig, 
rotation of screw 4b can be accomplished in a much more simple and 
efficient manner as compared with the case in which screw 4b is manually 
rotated. 
As in the foregoing, by separately rotating screw 4b and protrusion 4d 
after inserting screw 4b into through hole 1a and cutout portion 2a, 
protrusion 4d and the bottom surface of cover 2 can be engaged and head 4a 
is moved in a direction which comes closer to tube like portion 4c. 
Therefore, cover 2 and decking 1 can be pinched and fixed between the 
bottom surface of head 4a and the upper surface of protrusion 4d. 
It is noted that in the above described embodiment, a stacked structure of 
cover 2 made of concrete and decking 1 is fixed using fixture 4. The 
present invention is also applicable to any plate other than that 
mentioned above, as long as a plurality of such plates are provided in a 
stack. In addition, while cutout portion 2a is formed at the end of cover 
2 in the above described embodiment, the present invention is also 
applicable even when a through hole passing through cover 2 in a direction 
of thickness is provided. Further, as for the shape of protrusion 4d, the 
shape other than that shown in FIGS. 1 to 5 may be used as long as it 
allows passage thereof through the first through hole 1a and cutout 
portion 2a and engagement with the bottom surface of cover 2 by rotation 
thereafter. 
Although the present invention has been described and illustrated in 
detail, it is clearly understood that the same is by way of illustration 
and example only and is not to be taken by way of limitation, the spirit 
and scope of the present invention being limited only by the terms of the 
appended claims.