U.S. patent application number 13/456494 was filed with the patent office on 2012-11-01 for sheet metal repair jig.
Invention is credited to Akio Hirane.
Application Number | 20120272705 13/456494 |
Document ID | / |
Family ID | 46084722 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120272705 |
Kind Code |
A1 |
Hirane; Akio |
November 1, 2012 |
SHEET METAL REPAIR JIG
Abstract
A sheet metal repair jig for smoothening a sheet metal by
heating and cooling a part of the sheet metal to be repaired
includes at least one roller having a cylindrical shape, the roller
being made of an electrically-conductive material and serving as a
heating means; a roller support shaft supporting the roller
pivotably about an axis of rotation of the cylindrical shape; a
support supporting the roller support shaft and having an electrode
electrically connected to the roller; and a cooling channel serving
as an air channel for discharging cooling air to a contact surface
between the part of the sheet metal to be repaired and the roller.
The cooling channel is formed inside the roller support shaft and
has a discharge port that discharges the cooling air to the contact
surface between the part of the sheet metal to be repaired and the
roller.
Inventors: |
Hirane; Akio; (Tokyo,
JP) |
Family ID: |
46084722 |
Appl. No.: |
13/456494 |
Filed: |
April 26, 2012 |
Current U.S.
Class: |
72/200 |
Current CPC
Class: |
B21D 1/06 20130101 |
Class at
Publication: |
72/200 |
International
Class: |
B21B 27/06 20060101
B21B027/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2011 |
JP |
2011-101763 |
Claims
1. A sheet metal repair jig for smoothening a sheet metal by
heating and cooling a part of the sheet metal to be repaired,
comprising: at least one roller having a cylindrical shape, the
roller being made of an electrically-conductive material and
serving as a heating means; a roller support shaft supporting the
roller pivotably about an axis of rotation of the cylindrical
shape; a support supporting the roller support shaft and having an
electrode electrically connected to the roller; and a cooling
channel serving as an air channel for discharging cooling air to a
contact surface between the part of the sheet metal to be repaired
and the roller, wherein the cooling channel is formed inside the
roller support shaft and has a discharge port that discharges the
cooling air to the contact surface between the part of the sheet
metal to be repaired and the roller.
2. The sheet metal repair jig according to claim 1, wherein the
sheet metal repair jig includes a plurality of rollers arranged
along the axis of rotation, and the discharge port is formed in a
gap between the plurality of rollers.
3. The sheet metal repair jig according to claim 2, wherein the
sheet metal repair jig includes two rollers of the same size and
shape arranged along the axis of rotation, and the discharge port
is formed in a gap between the two rollers.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Japanese Application
No. 2011-101763, filed Apr 28, 2011, which is hereby incorporated
by reference herein in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to a sheet metal repair jig
for repairing dents or distortions generated in a curved surface or
in a peripheral surface of a sheet metal used for vehicles or the
like.
BACKGROUND
[0003] In repairing dents or distortions in a sheet metal of, for
example, an automotive body which were caused by contact, crash,
etc., first, the location of a dent or distortion is identified,
accessories of a panel requiring repairs are detached, and coating
applied to the identified location of the dent or distortion is
removed. Next, with a puller or the like, the sheet metal having
the dent or distortion is roughly flattened out by pulling,
hammering, welding, etc. Then, the dent or distortion is heated and
cooled repeatedly so as to utilize expansion due to heating and
contraction due to cooling.
[0004] As a sheet metal repair jig for repairing dents or
distortions in a sheet metal, the following art has been proposed
(see JP Utility Model Appl. Publ. No. 3,154,968). This sheet metal
repair jig includes: a roller serving as a heating means; a roller
shaft for pivotably supporting the roller; and a U-shaped holding
frame serving as a bearing for the roller shaft. By using this
roller as a heat source and moving the roller at constant speed and
in contact with a part to be repaired, an uneven heat distribution
in the sheet metal is suppressed and repair works can be carried
out without producing scratches.
[0005] As mentioned above, works for repairing dents or distortions
in a sheet metal require heating and cooling to be repeated. In
this respect, in the aforementioned conventional art, the use of a
roller has facilitated the heating operation itself. However, to
cool a part of a sheet metal to be repaired, the operator had to
put a heating roller down and then pick up a separately-prepared
cooling device to perform a cooling operation. Therefore, the
operator needed to use the heating device and the cooling device
alternately in carrying out the repair work, which was troublesome
to the operator.
[0006] Further, high tensile strength steel sheets or the like used
for recent automotive bodies are weak against heat, and thus needs
to be expanded by being heated at a low temperature. It is
important that the steel plate is cooled immediately after heating
in order to avoid an excessive temperature rise. However, in the
conventional sheet metal repair jig, since the operator each time
had to alternate between the heating means and the cooling means,
it was difficult to cool the sheet metal immediately after heating.
Further, when there was a time lag from heating to cooling, the
temperature of the heated part may become higher than the control
temperature of the heating means, depending on the degree of
contact between the heated part of the sheet metal and the
roller.
[0007] The present invention proposes to solve the aforementioned
problem of the conventional art, and it is an object of the present
invention to provide a sheet metal repair jig that can smoothly
heat and cool a part of a sheet metal to be repaired to enhance
precision of repair and to reduce the operator's workload.
SUMMARY
[0008] In order to solve the aforementioned problem, according an
aspect of the invention, a sheet metal repair jig for smoothening a
sheet metal by heating and cooling a part of the sheet metal to be
repaired, includes:
[0009] at least one roller having a cylindrical shape, the roller
being made of an electrically-conductive material and serving as a
heating means;
[0010] a roller support shaft supporting the roller pivotably about
an axis of rotation of the cylindrical shape;
[0011] a support supporting the roller support shaft and having an
electrode electrically connected to the roller; and
[0012] a cooling channel serving as an air channel for discharging
cooling air to a contact surface between the part of the sheet
metal to be repaired and the roller,
[0013] wherein the cooling channel is formed inside the roller
support shaft and has a discharge port that discharges the cooling
air to the contact area between the part of the sheet metal to be
repaired and the roller.
[0014] According to the above aspect, cooling air is discharged to
an area in the vicinity of the roller of the sheet metal repair jig
that is in contact with a part to be repaired. Therefore, it is
possible to cool the sheet metal immediately after heating with the
roller. Also, using this roller for heating allows not only a
drawing process but also smoothing of a surface to be repaired with
the roller, enabling a more precise repair.
[0015] Since a sheet metal used for automotive bodies or the like
is formed into a curved surface or the like, a residual internal
stress exists. In this case, after the heating, if the heated sheet
metal is subject to natural heat radiation or is left to let cool,
the shape etc. of the curved surface of the sheet metal is
distorted. Therefore, the sheet metal needs to be cooled
immediately after heating. In this respect, in the present aspect,
the sheet metal can be cooled immediately after heating, since
cooling air is discharged from a discharge port through a cooling
channel simultaneously with the heating by the roller.
[0016] According to this aspect of the invention, particularly, it
is possible to repair heat-sensitive materials, e.g., high tensile
strength steel sheets, at a low temperature, since the steel plate
can be prevented from reaching an unnecessarily high temperature
even when heated by the roller.
[0017] Conventionally, since the heating means and the cooling
means were separately provided, after a part of a sheet metal to be
repaired has been heated, the operator puts down a heating device
used for heating and then holds a cooling device to carry out
cooling. In this respect, according to the present aspect, both
heating and cooling can be performed with a single device, thereby
significantly eliminating the burden on the operator.
[0018] As a device for discharging gases in the vicinity of the
point of operation, such devices as those used for CO.sub.2 welding
or MAG welding are typically known. However, the discharge gas of
these devices serves as a shielding gas for preventing a metal
melted by arc welding from being exposed to air. Accordingly, this
discharge gas totally differs from the cooling air of the present
invention in terms of technical idea.
[0019] The temperature of the roller may increase above the control
temperature due to an increase and decrease in the resistance
depending on the extent of contact area or due to contact over a
long period of time. In this respect, in the present aspect, since
the sheet metal can be cooled by the cooling means immediately
after the roller has contacted the sheet metal, the temperature is
less influenced by both the contact area or the contact time. Thus,
in sheet metal repair works in which expert skills are ultimately
of importance, it is possible to provide a jig that eliminates the
difference in skill between the inexperienced operator and the
expert.
[0020] Preferably, the sheet metal repair jig includes a plurality
of rollers arranged along the axis of rotation, and the discharge
port is formed in a gap between the plurality of rollers.
[0021] With the sheet metal repair jig of the above configuration,
the sheet metal repair jig includes the plurality of rollers, and
the discharge port for discharging cooling air is formed in a gap
therebetween. Therefore, the cooling air can be supplied uniformly
in the width direction of the contact surface between a part of the
sheet metal to be repaired and the roller (in a direction of the
roller shaft).
[0022] Preferably, the sheet metal repair jig includes two rollers
of the same size and shape, and the discharge port is formed in a
gap between the two rollers.
[0023] With the sheet metal repair jig of the above configuration,
the sheet metal repair jig includes two rollers, and a port for
discharging cooling air is formed in a gap situated centrally
between the rollers. By discharging the cooling air from the
discharge port toward a contact surface between the roller and the
sheet metal, the cooling air can be supplied uniformly across the
entire contact surface between the roller and a part of the sheet
metal to be repaired.
[0024] According to the aforementioned present invention, it is
possible to provide a sheet metal repair jig that can smoothly heat
and cool a part of a sheet metal to be repaired to enhance
precision of repair and to reduce the operator's workload.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a perspective view illustrating an overall
constitution of a sheet metal repair jig according to an embodiment
of the present invention.
[0026] FIG. 2 is a plan view illustrating an overall constitution
of a sheet metal repair jig according to an embodiment of the
present invention.
[0027] FIG. 3 is a schematic side view illustrating an operation of
a sheet metal repair jig according to an embodiment of the present
invention.
[0028] FIG. 4 is a plan view illustrating an overall constitution
of a sheet metal repair jig according to another embodiment of the
present invention.
[0029] FIG. 5 is a perspective view illustrating an overall
constitution of a sheet metal repair jig according to another
embodiment of the present invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0030] Hereinafter, the present invention will be described with
reference to the drawings illustrating embodiments thereof
1. Present Embodiment
[0031] A sheet metal repair jig 1 according to an embodiment
(hereinafter the present embodiment) is a jig configured to repair
a sheet metal made of, for example, a general steel plate, an
aluminum sheet metal, a stainless-steel sheet metal or a high
tensile strength steel sheet by smoothening a part of the sheet
metal to be repaired by heating and cooling. As shown in FIGS. 1
and 2, the sheet metal repair jig 1 includes: a roller 2 having a
cylindrical shape and made of an electrically-conductive material;
a roller support shaft 3 supporting the roller 2 pivotably about an
axis of rotation of the cylinder; a support 4 supporting the roller
support shaft 3; an electrode 5 disposed at one end of the support
4 and electrically connected to the roller 2; and a cooling channel
6 serving as a channel for discharging cooling air to a contact
surface of the roller 2.
[0032] The roller 2 is a heating means which produces resistive
heat when an electric current is passed through. The roller 2 has a
cylindrical shape and is made of an electrically-conductive
material such as copper or ferrite. In the present embodiment,
sheet metal repair jig includes two rollers of the same size and
shape, or, the roller 2 includes two portions (rollers 2a, 2b) of
the same size and shape. A gap between the two rollers 2a, 2b is
preferably as small as possible as long as the function of the
discharge port 6b is achieved, although it depends on a size of a
discharge port 6b to be described later.
[0033] Here, the roller 2 is made of copper or ferrite, and not of
carbon as disclosed in JP Utility Model Appl. Publ. No. 3,154,968,
which is mentioned above. This is due to the following reasons. In
JP Utility Model Appl. Publ. No. 3,154,968, heat generation
performance is maintained without generating an arc. However, as
pointed out in JP Utility Model Appl. Publ. No. 3,154,968, carbon
is less wear-resistant than copper and wears down at a higher rate.
Therefore, when used for a roller, there were cases where a part of
a sheet metal to be repaired could not be flattened out
appropriately due to worn away unsmooth carbon. In the present
embodiment, this disadvantage of carbon is eliminated by adjusting
a current flowing into the roller, as well as by providing a
cooling means described below and using copper or ferrite which is
more wear-resistant.
[0034] The roller support shaft 3 is a rod-shaped object which
pivotably supports the two rollers 2a, 2b. The roller support shaft
3 has a hollow section extending from one end to an intermediate
position, i.e., an almost central position in the width direction,
forming a cooling channel 6 to be described hereinafter. Further,
the discharge port 6b described below is formed in a gap part
between the two rollers 2a, 2b.
[0035] The support 4 is U-shaped in a plan view and is configured
to support the roller support shaft 3 at both end portions. In the
present embodiment, as shown in FIG. 1, the roller support shaft 3
is internally-threaded at both end portions and is secured to the
support 4 with nuts N such that the support 4 is sandwiched
therebetween. It is to be noted that the method of securing the
support shaft 3 to the support 4 is not limited to this securing
manner, but any publicly-known various securing methods may be
employed as long as the roller support shaft 3 is secured to the
support 4.
[0036] The electrode 5 is formed at a bottom part of the U-shape of
the support 4 having a U-shaped configuration in a planar view and
is disposed in a direction perpendicular to the roller support
shaft 3. The electrode 5 serves as a connecting portion to be
electrically connected to an external current supply unit, which is
not shown. As such a current supply unit, a publicly-known device
such as the one disclosed as a sheet metal repair jig body in JP
Utility Model Appl. Publ. No. 3,154,968 is used.
[0037] The roller 2, the roller support shaft 3, the support 4 and
the electrode 5 are each comprised of an electrically-conductive
member. An electric current which is input into the electrode 5 via
the external current supply unit, which is not shown, flows into
the roller 2 through the support 4 and the roller support shaft
3.
[0038] The cooling channel 6 is a cooling air conveying path that
is formed in a hollow in the roller support shaft 3. At one end
portion of the cooling channel 6, an air intake port 6a for
introducing air from an external blower (publicly-known), which is
not shown, is provided. At the other end portion thereof, the
discharge port 6b that discharges the introduced air is provided. A
flow channel 6c is formed between the air intake port 6a and the
discharge port 6b.
[0039] The air intake port 6a is formed at one end portion at which
the support 4 pivotably supports the roller support shaft 3, and
when an air-blast nozzle of the blower is connected to the air
intake port 6a, the air intake port 6a becomes a port for
introducing cooling air. The discharge port 6b in a gap between the
two rollers 2 is formed at an axially central portion of the roller
support shaft 3.
[0040] The discharge port 6b is formed by a nozzle 6n. With this
nozzle 6n, a discharge direction of the discharge port 6b is
directed towards a direction of a contact surface in which the
roller 2 contacts the sheet metal, i.e., a direction perpendicular
to a direction of a plane in the plan view of FIG. 2. A setting
angle of the discharge direction is determined based on the reason
described below. When using the sheet metal repair jig 1 in repair
work, a connecting portion of a current supply unit, which is not
shown, is connected to the electrode 5. The connecting portion of
the current supply unit is exteriorly provided with a handle made
of an insulating material. The operator grips the handle and moves
the repair jig with the U-shaped plane surface of the support 4
being substantially aligned with the plane surface of the sheet
metal (see FIG. 3). Therefore, with a discharge port being provided
in a direction of the U-shaped planar surface of the support 4, the
discharge port 6b can supply cooling air in the vicinity of the
contact surfaces between the two rollers 2a, 2b and the sheet
metal. As described above, the discharge direction of the discharge
port 6b set by the nozzle 6n is directed toward the contact surface
between the roller 2 and the sheet metal. However, the direction of
the discharge port 6b can be varied appropriately, depending on an
angular relationship between the electrode 5 or the operator handle
and a surface of the sheet metal to be repaired. Preferably, the
direction of the discharge port 6b is set in a direction in which
cooling air directly hits a surface of the sheet metal to be
repaired.
[0041] In the present embodiment, any type of gas, e.g., air and
nitrogen, as well as carbonic acid gas (CO.sub.2), can be used as
air to be discharged from the discharge port 6b, as long as a part
of the sheet metal to be repaired can be cooled.
[0042] The sheet metal repair jig 1 of the present embodiment
constituted in the foregoing manner operates in the following
manner. First, the electrode 5 of the sheet metal repair jig 1 is
connected to an external current supply unit (publicly-known device
is used), which is not shown. In turn, an air-blast nozzle of a
blower (publicly-known), which is not shown, is connected to the
air intake port 6a provided at one end of the roller support shaft
3 so as to define an air flow path of cooling air.
[0043] Next, the operator grips the handle provided at the
connecting portion of the external current supply unit connected to
the electrode 5 and starts operation. At this time, the current
value of the external current supply unit is controlled to control
the temperature at which the sheet metal repair jig 1 contacts the
sheet metal.
[0044] Then, while gripping the handle, the operator makes the
roller 2 contact a part of the sheet metal to be repaired and rolls
the roller 2 with respect to the surface to be repaired. At this
time, a predetermined electricity flows into the roller 2 from the
external current supply unit via the electrode 5, the support 4 and
the roller support shaft 3 and a resistive heat is produced in the
contact surface between the roller 2 and the sheet metal, and
thereby a part of the sheet metal to be repaired is heated.
Simultaneously, cooling air is supplied from the external blower.
The cooling air passes through the air intake port 6a and the
cooling channel 6 and is discharged from the discharge port 6b.
[0045] Here, as shown in a schematic side view of FIG. 3, when the
sheet metal repair jig 1 is in use, the nozzle provided on the
discharge port 6b of the cooling channel 6 is provided so as to be
almost opposite a surface of the sheet metal to be repaired A.
Therefore, cooling air to be discharged from the nozzle is
discharged from a region between the two rollers 2a, 2b, hits the
surface of the sheet metal to be repaired, spreads to right and
left, and further spreads out across the contact surfaces between
the rollers 2a, 2b and the sheet metal.
[0046] In the sheet metal repair jig 1 of the present embodiment
described above, since the cooling air is discharged to an area in
the vicinity of the roller 2 which is in contact with a part to be
repaired, the heated part can be immediately cooled after the
heating with the roller 2. Also, with the heating by such a roller,
smoothing of the surface to be repaired with the roller as well as
a drawing process is possible and a more precise repair is
enabled.
[0047] Since a sheet metal used for automotive bodies or the like
is formed into a curved surface or the like, a residual internal
stress exists. In this case, after the heating, if the heated sheet
metal is subjected to natural heat radiation or is left to let
cool, the shape of the curved surface etc. of the sheet metal is
distorted due to the residual stress. Therefore, the sheet metal
needs to be cooled immediately after heating. In this respect, with
the sheet metal repair jig 1 of the present embodiment, the sheet
metal can be cooled immediately after heating, since cooling air is
discharged from the discharge port 6b through the cooling channel 6
simultaneously with the heating by the roller 2. Particularly, it
is possible to repair heat-sensitive materials, e.g., high tensile
strength steel sheets, at a low temperature since the steel sheet
can be prevented from reaching an unnecessarily high temperature by
being heated with the roller 2.
[0048] Conventionally, since the heating means and the cooling
means were separately provided, after a part of a sheet metal to be
repaired has been heated, the operator puts down the sheet metal
repair jig 1 used for the heating and then holds a cooling device
to carry out cooling. In this respect, with the sheet metal repair
jig 1 according to the present embodiment, both heating and cooling
can be performed with a single device, thereby significantly
eliminating the burden on the operator.
[0049] As a device for discharging gases in the vicinity of the
point of operation, such devices as those used for CO.sub.2 welding
or MAG welding are typically known. However, the discharge gas of
these devices serves as a shielding gas for preventing a metal
melted by arc welding from being exposed to air. Accordingly, this
discharge gas totally differs from the cooling air of the sheet
metal repair jig according to the present invention in terms of the
technical idea.
[0050] The temperature of the roller 2 may increase above the
control temperature due to an increase or decrease in the
resistance depending on the extent of contact area, or due to
contact over a long period of time. In this respect, with the sheet
metal repair jig 1 of the present embodiment, since the sheet metal
can be immediately cooled by the cooling means after the roller has
contacted the sheet metal, the temperature is less influenced by
the contact area or the contact time. Thus, in sheet metal repair
works in which expert skills are ultimately of importance, it is
possible to provide a jig that eliminates the difference in skill
between the inexperienced operator and the expert.
[0051] Also, a plurality of rollers 2 are arranged along the axis
of rotation, or, the roller 2 is divided into portions (in this
case, into two), and the discharge port 6b for discharging cooling
air is formed in a gap therebetween. Therefore, as shown in FIG. 3,
the cooling air can be supplied uniformly in the width direction of
the contact surface between a part of the sheet metal to be
repaired and the roller (in direction of the roller shaft).
Particularly, in the present embodiment, two rollers are arranged
along the axis of rotation, or, the roller is divided into two
sections, and a port for discharging cooling air is formed in a gap
situated centrally between the rollers. By discharging the cooling
air from the discharge port formed opposite the contact surface
between the roller and the sheet metal, the cooling air can be
supplied uniformly across the entire contact surface between the
roller and a part of the sheet metal to be repaired.
2. Other Embodiment
[0052] The present invention is not limited to the aforementioned
embodiment but may include the embodiment described below.
Specifically, although in the present embodiment, two rollers 2 are
arranged along the axis of rotation, or, the roller 2 is divided
into two sections, and the discharge port 6b is formed in the
support shaft 3 centrally between the two rollers, the present
invention is not limited to this embodiment, and three or four, or
more rollers may be provided, or, the roller may be divided into
three or four, or more sections.
[0053] For example, like a sheet metal repair jig 10 shown in FIG.
4, three rollers 20 are arranged along the axis of rotation, or,
the roller 20 is divided into three, and two air intake ports 60a
are provided at both ends of the rollers 20 so that the discharge
ports 60b are formed in the two gaps between the rollers 20. In
this embodiment, as shown in FIG. 4, the constitution can be
employed as follows. Flow channels 60c are formed by the hollow
sections of a roller support shaft 30, the flow channels 60c
extending from both ends of the roller support shaft 30,
respectively, to the first discharge ports 60b situated in the
one-third positions in the width direction so that two cooling
channels 60 beginning from both ends are formed, and two discharge
ports 60b are formed accordingly. Also, as a variant, although not
shown, another constitution may be employed wherein a hollow
section is formed to extend from one end of the roller support
shaft to the two-thirds position in the width direction so that a
flow channel is provided, and discharge ports are provided in the
middle and end portions.
[0054] In this embodiment, the discharge direction of the nozzle 6n
comprised of the discharge port 6b is directed in a direction
perpendicular to the direction of the plane in the plan view of
FIG. 2. However, the present invention is not limited to this
embodiment, but for example, the discharge direction of the nozzle
6n can be directed in the same direction as the axis of the
electrode 5, i.e., in a directly downward direction in a
perspective view of FIG. 1 or in a schematic view of FIG. 3.
Alternatively, the discharge direction of the nozzle 6b may be
directed in an oblique direction, which is an intermediate
direction between the direction perpendicular to the direction of
the plane of the plan view of FIG. 2 and a direction which is the
same as the direction of the axis of the electrode 5. In other
words, depending on the angle at which the roller 2 contacts a part
of the sheet metal to be repaired, the discharge direction of the
nozzle 6n is preferably directed in the same direction as the
direction in which the roller contacts the sheet metal. It is also
possible to employ another constitution wherein, for example, the
nozzle 6n is pivotably attached to the support shaft 3 so that the
discharge direction of the discharge port 6b for cooling air with
the nozzle 6n is variable.
[0055] As a variant of the embodiment shown in FIG. 1, in addition
to the embodiment in which cooling air is introduced from the end
portion of the support shaft 3, an embodiment shown in FIG. 5 is
possible. FIG. 5 is a schematic plan view of a sheet metal repair
jig 20 according to the variant. In FIG. 5, for the sake of
convenience of explanation, the support 4 is cut out above the
roller 2 and illustrated in cross section.
[0056] As with the sheet metal repair jig 20 shown in FIG. 5,
another constitution may be employed wherein a cooling channel 61
is formed perpendicular to the support shaft 3 in a gap between the
rollers 2a, 2b and an air intake port 61a for cooling air is formed
in an end portion of the cooling channel 61. In order to supply
air, a hose (shown by a phantom line in the drawing) extending from
an external blower, which is not shown, is attached to the air
intake port 61a of the cooling channel 61. Also, in this case, a
discharge port 61b is formed on the straight line of the
introduction path of the cooling channel 61. The manner of using
the sheet metal repair jig 20 is the same as the embodiment shown
in FIG. 3.
[0057] Also, in this embodiment, as shown in FIG. 5, it is also
conceivable to provide a constitution in which, in a portion of the
support shaft 3 covered with the roller 2, the cooling channel 61
situated centrally between the rollers 2a, 2b diverges horizontally
inside the support shaft 3 and penetrate into end portion positions
of the support shaft 3, and the ventilation holes 61d which
communicate the cooling channel 61 inside the support shaft 3 with
the rollers 2a, 2b and, are provided at central portions of the
rollers 2a, 2b.
[0058] In this way, by providing the ventilation holes 61d in a
portion of the support shaft 3 covered with the rollers 2a, 2b, a
flow of air discharged from the ventilation holes 61d is produced
within small clearances between the support shaft 3 and the
backside of the rollers 2a, 2b, as indicated by the arrows in FIG.
5. This enables the rollers 2a, 2b to be cooled by the cooling air.
Thus, it is possible to carry out repair treatment while the
rollers 2a, 2b are kept at a low temperature to some extent.
[0059] The ventilation hole 61d may be of a circular or rectangular
shape. Also, the ventilation hole 61d may be a single hole or a
plurality of holes provided in each roller. Further, in FIG. 5,
from a design point of view, the cooling channel 61 penetrates
through the support shaft 3, and both ends are closed with the nuts
N with caps. However, there are no functional problems as long as
both end portions of the cooling channel 61 extend from the central
portion in which the air intake port 61a and the discharge port 61b
are formed to the positions of both ventilation holes 61d.
* * * * *