Wire reel for use in a binding machine

A wire reel (3) for winding a binding wire thereround includes, on the outside surface of at least one of two frame plates, a recessed portion (15) consisting of a peripheral wall portion (14) having its center at the axis of the reel and a bottom wall portion (12). An optical sensor detection mark (17) is provided in the recessed portion (15) such that the mark (17) is disposed eccentric from the axis of the reel. The peripheral wall portion (14) of the recessed portion (15) is formed as a rotary shaft portion which is rotatably supported by the reel support portion of a binding tool. Since the recessed portion (15) is completely covered by the reel support portion of the binding tool, the optical sensor detection mark (17) provided in the recessed portion (15) is completely free from the influences of the external environment. Thus, even if the weather and indoor or outdoor operation sites using the binding tool and the like vary, the rotation of the wire reel (3) can be detected accurately to thereby effectively prevent operation errors.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a reel for holding binding wire. The reel 
with the binding wire is mounted to a binding tool which is used to bind 
objects of interest. Specifically, the wire contained on the reel is fed 
to the binding tool which cuts and twists the wire around architectural 
reinforcing bars. 
2. Description of the Related Art 
In reels of this type, the connection of the terminal end of the wire held 
on the reel is used to control the rotation of the reel. Thus, if the 
terminal end of the wire held on the reel is not directly connected to the 
reel, the reel cannot be rotated, In this method, the ability of the reel 
to rotate is used to determine whether or not all the wire on the reel has 
been used in the binding operations. Thus, when the reel can no longer be 
rotated, the wire supply on the reel has been exhausted. When the wire 
supply has been exhausted, the binding process is then brought to a stop. 
In order to simplify the process for determining when the supply of wire 
has been exhausted and for bringing the binding operation to a stop, an 
optical sensor system may be used. Reflected light through a detection 
mark formed on the side surface of the reel may be detected by an optical 
sensor. The optical sensor system consists of a light emitting element and 
a light receiving element respectively disposed opposite each other in the 
reel support portion of the binding tool. 
However, because tools such as a binding tool and the like are used in a 
variety of lighting conditions, detection errors with the optical sensor 
system caused by the differences in the light intensities in different 
environments cannot be avoided. For example, differences in light 
intensities between the outdoors and various lighting conditions indoors 
frequently result in erroneous readings in the optical sensor system 
attached to such binding tools. Such erroneous readings can interfere with 
the operation of the binding tool and thereby prevent the stable operation 
of the binding process. 
SUMMARY OF THE INVENTION 
It is in an object of the present invention to provide a wire reel which 
allows the rotation of the reel to be detected with certainty without the 
influence of variable environmental lighting conditions on the binding 
process. 
In attaining the above object, according to the present invention, there is 
provided a wire reel for use in a binding tool for binding reinforcing 
bars and the like by use of a binding wire to be wound round the wire 
reel, in which a recessed portion, consisting of a peripheral wall portion 
and a bottom wall portion and having its center on the central axis of 
said reel, is formed on the outside surface of at least one of two frame 
plates provided in the wire reel, an optical sensor detection mark is 
provided eccentrically from the axis of the reel on the bottom wall 
portion surface of the recessed portion, and the peripheral wall portions 
of the recessed portion are formed as a rotary shaft portion to be 
supported rotatably in the reel support portion of the binding tool for 
binding reinforcing bars and the like. 
According to the above-mentioned structure, since the wire reel includes 
the recessed portion serving as the rotary shaft, by providing a cover 
portion for the opening of the recessed portion and an optical sensor in 
the reel 10 support portion of the binding tool, the interior of the 
recessed portion can be shielded completely from the outside by the 
recessed portion itself and the cover portion of the reel support portion 
of the binding tool. This shielding completely eliminates the influence of 
external environmental lighting conditions on the optical sensor detection 
system. Therefore, even if the weather and/or outdoor or indoor operation 
sites using the binding tool and the like vary, the rotation of the wire 
reel can be detected with accuracy to thereby effectively eliminate or 
prevent the occurrence of operational errors.

The following references numbers are used throughout the figures: 
1 Main body portion of binding tool, 
2 Guide portion of the binding tool, 
3 Wire reel, 
3a Disk-shaped frame plate of reel, 
3b First cylinder portion of wire reel, 
4 Wire, 
5 Wire guide hole of binding tool, 
6 Feed mechanism of binding tool, 
7 Cutting mechanism of binding tool, 
8 Twisting mechanism of binding tool, 
9 Hook, 
10 Wire reel mounting arm of binding tool, 
11 Wire reel mounting arm of binding tool, 
12 Bottom wall portion of wire reel, 
13 Second cylinder portion of reel, 
14 Peripheral wall portion of reel, 
14a Inner peripheral wall portion, 
14b Outer peripheral wall portion, 
15 Recessed portion of reel, 
16 Radially extending ribs, 
17 Optical sensor detection mark, 
18 Support shaft of binding tool, 
18a Enlarged head portion of shaft, 
19 Spring, 
21 Annular projection, 
22 Optical sensor, 
23 Control board for the optical sensor, 
24 Control part, 
30 Object to be bound and 
40 Space portion. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a binding tool, in which reference character 1 designates the 
main body portion of the binding tool, 2 represents a guide portion of the 
binding tool and 3 represents a reel around which a binding wire 4 is 
wound. The main body portion 1 of the binding tool includes a wire guide 
hole 5 through which the binding wire 4 is extended longitudinally, and 
also includes a feed mechanism 6 for extruding the wire 4 from the wire 
reel 3 and feeding the wire 4 to the guide portion 2, a cutting mechanism 
7 for cutting the feed wire 4 at the front end guide outlet of the wire 
guide hole 5, and a twisting mechanism 8 for hitching a hook 9 round the 
wire 4 wound around an object 30 to be bound, such as a reinforcing bar 
and the like, by the guide portion 2 and twisting of the hook 9. 
In FIG. 2, a pair of wire reel mounting arms 10 and 11 are provided 
projectingly on and from the main body portion 1 of the binding tool, and 
the wire reel 3 with the binding wire 4 wound thereround is removably and 
rotatably supported between the arms 10 and 11. 
The wire reel 3 is comprised of a pair of disk-shaped frame plates 3a and a 
first cylinder portion 3b connecting the two frame plates 3a. A bottom 
wall partition 12 is formed within the cylinder portion 3b of the reel in 
the middle of the cylinder portion 3b. A second cylinder portion 13 having 
a diameter smaller than that of the first cylinder portion 3b is connected 
to one of the frame plates 3a. A recessed portion 15 of the reel is formed 
by a wall portion defined by a bottom partition wall 12 and a peripheral 
wall portion 14. The recessed portion 15 has its center at or on the 
central axis of the reel 3. Radially extending ribs 16 are provided on and 
from the bottom wall portion 12, and an optical sensor detection mark 17 
is provided on the leading end face of one of the ribs 16 in such a manner 
that it is eccentric from the central axis of the reel 3. The peripheral 
wall portion 14 comprises two parts, that is, an inner peripheral wall 
portion 14a having a small diameter and an outer peripheral wall portion 
14b having a larger diameter. 
Next, the small diameter second cylinder portion 13 provided on the one 
frame plate 3a of the bottom wall partition 12 of the wire reel 3 and the 
peripheral wall portion 14 formed on the other frame plate of the 
partition wall 12 are respectively arranged as a rotary shaft portion with 
respect to the binding tool. 
That is, inside the leading end of arm 10 projecting backwardly of the main 
body portion 1 of the binding tool, there is provided a support shaft 18 
as a wire reel support portion which is projected toward wire reel 
mounting arm 11 and is movable in the axial direction. The wire reel 
support shaft 18 is energized in the projecting direction thereof by a 
spring 19 and is also arranged such that the enlarged head portion 18a 
provided in the leading end thereof can be fitted with the small diameter 
second cylinder portion 13 of the wire reel 3 to support the wire reel 3 
rotatably. 
On the other hand, inside the leading end of wire reel mounting arm 11, 
there is provided a an annular projection 21 having a recess-shaped 
section as a wire reel support portion. The annular projection 21 is 
fitted within the interior of the large diameter outer peripheral wall 
portion 14b of the wire reel 3 to support the wire reel rotatably. 
The annular projection 21 covers the opening of the recessed portion 15 of 
the wire reel 3. Therefore, by means of the peripheral wall portion 14 and 
bottom wall portion 12 forming the recessed portion 15 and the annular 
projection 21 of the reel support portion, there is formed in the interior 
of the recessed portion 15, a space portion 40 which is completely covered 
from the outside. 
To mount the wire reel 3 onto the main body portion 1 of the binding tool, 
the reel 3 is inserted between the wire reel support portions of the main 
body portion 1 of the binding tool, i.e., between support shaft 18 and 
annular projection 21. The wire reel support shaft 18 is drawn in against 
the energizing force of the spring 19, the wire reel 3 is inserted between 
the two arms 10 and 11 and the annular projection 21 is fitted into the 
large diameter peripheral wall portion 14 of the wire reel 3. The wire 
reel support shaft 18 is then projected out by the spring 19 and is fitted 
within the small diameter second cylinder portion 13 of the wire reel 3. 
In FIG. 3, within the annular projection 21 of the wire reel support 
portion of the wire reel mounting arm, there is disposed an optical sensor 
22 consisting of a light emitting element and a light receiving element in 
such a manner that it can correspond to the moving locus of the optical 
sensor detection mark 17 of the wire reel 3. Reference character 23 
designates a control board for the optical sensor 22. The control board 23 
controls the optical sensor 22 such that the optical sensor 22 can operate 
only while the feed mechanism 6 of the binding wire 4 is operating, and 
also outputs a pulse signal to a control part 24 in the main body portion 
1 of the binding tool when the optical sensor 22 detects light reflected 
from the optical sensor detection mark 17 of the wire reel 3. 
The control part 24 controls the operations of the feed mechanism 6, 
cutting mechanism 7 and twisting mechanism 8. Specifically, as shown in 
the timing chart in FIG. 4, the control part 24 at first operates the feed 
mechanism 6 for a given period of time to allow the guide portion 2 to 
guide and wrap around the wire 4 into a loop shape and wind the loop wire 
4 around the object 30 to be bound, such as a reinforcing bar and the 
like. The control part 24 the operates the cutting mechanism 7 to cut the 
wire 4 and the twisting mechanism 8 to strongly bind the object 30 to be 
bound. In addition to this, when a pulse signal from the optical sensor 22 
is sent to the control part 24, the control part 24 operates the 
respective drive mechanisms continuously and, when any pulse signal is not 
received during the operation time of the feed mechanism 6, then the 
control part 24 immediately stops the operation of the cutting mechanism 
following the feed mechanism 6. 
According to the above description, in a normal wire binding operation, 
wire 4 is extruded from the wire reel 3 when the feed mechanism 6 is being 
operated. Thus, wire reel 3 is rotated around the axis of the 
above-mentioned rotary shaft portions (13, 14). In this case, since the 
optical sensor detection mark 17 of the wire reel 3 is sure to face the 
optical sensor 22 within the operation time of the feed mechanism 6, the 
optical sensor 22 will detect the reflected light from the optical sensor 
detection mark 17. Therefore, following the operation of the feed 
mechanism 6, the cutting mechanism 7 and twisting mechanism 8 are 
operated, so that the object 30 to be bound will be bound. 
On the other hand, when the amount of wire 4 on the wire reel 3 is 
depleted, exhausted or used up, the wire reel 3 ceases to rotate and at 
the same time the optical sensor detection mark 17 also stops rotating. In 
this case, since the 10 optical sensor detection mark 17 does not move to 
a position facing the optical sensor 22, the optical sensor 22 cannot 
detect the reflected light from the optical sensor detection mark 17 and 
thus no pulse signal is emitted or sent out. If no pulse signal from the 
optical sensor 22 is received by the control part 24, then the cutting 
mechanism 7 following the feed mechanism 6 is forced to stop. Therefore, 
an operator is able to know that the supply of wire 4 has been depleted 
and at the same time the last piece of binding wire 4 is not cut but 
remains as it is moved out from the front portion of the binding tool. 
Thus, if the wire 4 is pulled out from the front portion, then the wire 4 
within the wire guide hole 5 of the binding tool can be removed. 
Also, because the recessed portion 15 of the wire reel 3 is covered 
completely from outside by the cover portion (annular projection 21) of 
the reel support portion of the binding tool, the optical sensor detection 
mark 17 within the recessed portion 15 is completely free from the 
influences of the external environment. For this reason, even if the 
weather and indoor or outdoor operation sites using the binding tool and 
the like vary, the rotation of the wire reel 3 can be detected accurately 
to thereby effectively prevent occurrences of operation errors. 
It is also expected that the optical sensor detection mark 17 of the wire 
reel 3 can stop at a position facing the optical sensor 22. Accordingly, 
it is preferable that the optical sensor 22 is set not to output the pulse 
signal in this case as well. 
The number of the optical sensor detection marks 17 is not limited to 1. 
Two or more optical sensor detection marks 17 can be used, or they may be 
located on both sides of the wire reel 3. Also, the annular projection 21 
of the reel support portion of the binding tool may be arranged such that 
it can be fitted with the outside of the peripheral wall portion 14 of the 
recessed portion 15 of the wire reel 3. 
While the invention has been described in connection with what is presently 
considered to be the most practical and preferred embodiment, it is to be 
understood that the invention is not to be limited to the disclosed 
embodiment, but on the contrary is intended to cover various modifications 
and equivalent arrangements included within the spirit and scope of the 
appended claims. 
Thus, it is to be understood that variations in the particular shape and 
configuration of the disclosed wire reel can be made without departing 
from the novel aspects of this invention as defined in the claims.