JPH11333594A - Method for joining shaft to be welded and backing tool used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for joining shafts to be welded capable of making a joining part into a smaller diameter. SOLUTION: A clearance 3 between shafts to be welded 2 held by having the clearance 3 is filled with melting metal M by using a backing tool 4 and the two shafts to be welded 2, 2 are joined. The backing tool 4 is composed of a flowing stopper metal 5 made of a narrow band shaped metal sheet which is curved along the outer circumferential surface of the shafts 2 to be welded leaving an inlet port 7 for a welding material, spread over the two shafts to be welded 2, 2 and moreover, is allowed to be penetrated into a melting metal M and of a heat radiating framework 6 which absorbs the heat transmitting from the melting metal M to the flow stopper metal 5 by bringing the framework 6 into contact with the flowing stopper metal 5 and being engaged with it. By filling up the clearance 3 with the melting metal M, a joining part in which the melting metal M, the end surfaces 2a of the shafts to be welded 2 and the flow stopper metal 5 are integrally welded is formed. After that, the heat radiating framework 6 of the backing tool 4 is removed from the joining part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining a shaft to be welded, which is suitable for joining a reinforcing bar or the like constituting a reinforced concrete structure, and a backing tool used therefor.

[0002]

2. Description of the Related Art When arranging reinforcing bars in a reinforced concrete structure, for example, it is often the case that butting and joining of reinforcing bars arranged with their axial centers aligned vertically and vertically. As one of such joining methods, for example, a gas or electric pressure welding method is used. However, in this method, each end of the two rebars is melted and pressed in the axial direction to be joined, so that there is a problem that the length of the rebar becomes short after joining.

In the pressure welding method, as shown in FIG.
The diameter dimension d of the joint part a of the joined reinforcing bars c, c becomes extremely large, and when the concrete is poured after forming the formwork, a space b where the concrete does not sufficiently spread below the joint part a is formed. For example, there is a problem that the so-called “cover” of the concrete deteriorates at the joint portion a, and the strength and durability of the structure are likely to be reduced. That is, in order to improve the cover of the concrete and to construct an excellent structure, it is required to minimize the diameter of the joint portion a of the reinforcing bar and to reduce the difference from the reinforcing bar diameter.

In view of such circumstances, in recent years, the patent No. 2
A joining method using arc welding as disclosed in Japanese Patent No. 691697 has been proposed. In this method, as shown in FIG. 10, a reinforcing bar c held with a gap between the end faces,
c, a backing tool e having a substantially U-shaped cross section as shown in FIG.
And a welding rod or the like for arc welding is inserted from the opening i side of the backing tool e to fill the gap f between the end faces with the molten metal g. Thereby, the backing tool e is
It is integrated with the two rebars c, c and the molten metal g to form a joint a. According to this method, it is possible to prevent the rebar from being shortened after joining and to improve the covering of the concrete, as compared with the above-described pressure welding method.

[0005] By the way, such a joint h is usually
Good quality cannot be obtained unless continuous welding is performed with a large current of 200 A or more. Therefore, the backing tool e withstands the large current during the arc welding, and the molten metal g is formed outside the gap f. It is necessary to set the plate thickness w to prevent the leakage. For example, for arc welding of rebar having an outer diameter of about 20 to 32 mm, the thickness w of the backing device e is required to be at least 4 mm or more.

[0006] As described above, in the joining method using the arc welding method, the diameter of the joint portion h can be reduced as compared with the pressure welding method. Since it protrudes only by the thickness of the sheet, there is a possibility that the covering of the concrete may still be impaired, and further reduction in the thickness of such a backing tool has been desired.

[0007] The width of the backing member e along the axial direction of the reinforcing bar is conventionally set to a relatively large size that is two to three times or more the void amount h. When the width of the backing device e is large as described above, when a load that bends around the joint portion a is applied, the reinforcing bar c bends and deforms so as to lean on the end of the backing device e. In addition to losing the flexibility of a, it is conceivable that a large breaking stress acts on the joint portion a of the reinforcing bar with the end of the backing device e as a fulcrum.

On the other hand, it is also possible to form a joint having a small diameter while leaving only the molten metal by crushing the backing material after welding the rebar while forming the backing tool e of ceramics. Although it has been proposed, in this case, the backing device e is crushed every time the reinforcing steel is joined,
Material is wasted and resources cannot be used effectively.

The present invention has been devised in view of the above-mentioned circumstances, and a backing tool is provided in which a thin band-shaped thin metal plate curved along the outer peripheral surface of a shaft to be welded while leaving an insertion port for a welding material. And a heat-dissipating frame material into which the flow-stop fitting is fitted and absorbs heat transmitted to the flow-stop fitting, and the molten metal is filled in the gap to form a joint portion, and then the heat dissipation is performed. It is an object of the present invention to provide a joining method of a shaft to be welded, which is capable of further reducing the diameter of the joint portion on the basis of removing the frame material from the joint portion, and which can improve the covering of concrete, and a backing tool used therefor. And

[0010]

According to a first aspect of the present invention, a molten metal in which a welding material is melted is lined with the gap of a shaft to be welded held with a gap between end faces. A method of joining a shaft to be welded to join the shaft to be welded by filling with a tool, wherein the backing tool curves along the outer peripheral surface of the shaft to be welded, leaving an insertion port for a welding material. And a flow stop metal member formed of a thin band-shaped metal sheet straddling the two welded shafts, and a heat radiating frame for absorbing heat transmitted from the molten metal to the flow stop metal member when the flow stop metal member is fitted in contact with the flow stop metal member. And welding the flow stopper to the shaft to be welded and attaching a backing tool, and filling the gap with the molten metal formed by the arc of the welding material inserted into the gap, thereby forming the molten metal, The end face and the flow stopper are After forming the joint portion which is welded to the body, a bonding method of the welding shaft, characterized in that to remove the radiator frame member of said backing member from the joint portion.

According to a second aspect of the present invention, there is provided the heat dissipation frame member, wherein the cross-section is substantially semicircular or substantially U-shaped, and the flow-stopping metal member extends circumferentially along an inner peripheral surface thereof. 2. The method according to claim 1, wherein the fitting groove is formed, and the flow stopper is fitted flush or slightly with the inner peripheral surface.

According to a third aspect of the present invention, the flow stopper has a plate thickness of 0.5 to 2.3 mm and a gap amount h which is the axial length of the gap by 2 to 4 mm. 3. The method for joining shafts to be welded according to claim 1 or 2, wherein the joint has a large width and a total thickness of the fitted flow stopper and the heat radiation frame material is 4 mm or more.

According to a fourth aspect of the present invention, the heat radiating frame member is made of a material having a crush resistance, such as copper, brass or aluminum, which can be used repeatedly. 2. The method for joining shafts to be welded according to item 1.

According to a fifth aspect of the present invention, the flow stopper and the heat radiating frame have a hole formed concentrically at least on a side opposite to the insertion opening. The method according to any one of claims 1 to 4, wherein a diameter of the shaft is larger than a diameter of a hole of the flow stopper.

According to a sixth aspect of the present invention, there is provided a method for joining a shaft to be welded by filling the gap of the shaft to be welded held with a gap between end faces with a molten metal in which a welding material is melted. A backing device used for a method of joining welding shafts, wherein the narrow band shape is curved along the outer peripheral surface of the shaft to be welded while leaving an insertion port for a welding material and straddles the two shafts to be welded. The flow stopper made of a thin metal plate, and the heat transmitted from the molten metal to the flow stopper can be absorbed by being in contact with and fitted to the stopper, and the gap is filled with the molten metal to join the shaft to be welded. A backing tool comprising a heat radiation frame material which is later removed from the flow stopper.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings, taking as an example a reinforcing rod used in a reinforced concrete structure as a shaft to be welded. As shown in FIGS. 1 to 4, the joining method according to the present embodiment includes two rebars (welded shafts) 2 and 2 which are held with a gap 3 between the end faces 2 a and 2 a.
The gap 3 is filled with a molten metal M using a backing tool 4 to join the rebars 2 and 2.

The reinforcing bars 2 and 2 are arranged so that they are aligned with each other with their axial centers aligned vertically. For example, bar bars for reinforced concrete specified in JIS are preferable. In this embodiment, round bars having a circular cross section are exemplified. However, as shown in FIG. 8, as shown in FIG. 8, a deformed steel bar having projections formed on the surface to improve the compatibility with concrete, particularly D19 (nominal diameter: 19.1 mm) to D51
(Nominal diameter 50.8 mm) can be preferably used for joining reinforcing bars.

The gap 3 of the reinforcing bar is also referred to as a root gap or a groove gap. In the present embodiment, each end face 2a of the reinforcing bar 2 is parallel to each other and has a gap amount h (see FIG. 2) which is the axial length of the gap. Shown) is, for example, 5 to 15 mm, more specifically, 5 to 8 mm for a rebar having a D25 (nominal diameter of 25.4 mm).
Various adjustments are made depending on the diameter of the reinforcing bar.

In this embodiment, the rebars 2 are held in a predetermined butted state by a gripping jig 20 as shown in FIG. 6, for example. The gripping jig 20 includes a pipe-shaped base cylinder 21, a first holding part 23 fixed to one end of the base cylinder 21 and having a chuck part 22 at a tip end capable of gripping one rebar 2. The second holding unit 2 having an inner tube 29 slidably inserted into the base tube 21 and having a chuck unit 24 capable of gripping the other reinforcing bar 2.
And 5.

A nut member 27 is fixed to the opening end of the base cylinder 21, and a thread groove in a direction opposite to that of the nut member 27 is formed on the inner peripheral surface of the inner cylinder 29. The gap amount h can be finely adjusted by screwing the one slide adjusting screw 26 having the reverse screw formed therein into and out. Although not shown, the second holding unit 25
It is provided so as to be able to swing by a small angle around the axis center of the base cylinder 21, and the eccentricity can be prevented by appropriately aligning the axis centers of the reinforcing bars 2, 2.

As shown in FIG. 3, the backing member 4 is, in this embodiment, a flow stopper metal 5 made of a thin plate.
And a heat radiating frame member 6 to which the flow stopper metal fitting 5 is fitted. Normally, when a thin plate is continuously welded using an arc welding machine through which a large current flows, it cannot withstand heat and cannot stop the flow of molten metal. As a result of the integration, as described below, only the thin flow stopper 5 can be welded to the joint of the reinforcing bar.

As shown in FIGS. 1 to 3, the flow stopper metal 5 is curved along the outer peripheral surface of the reinforcing bar 2 except for the insertion port 7 for the welding material. It is preferable to form a semi-circular shape or a substantially U-shaped shape.
The figure shows an example. In addition, the flow stopper 5
In this embodiment, the metal is formed from a thin metal plate and a narrow band which is allowed to be melted into the weld metal M, and has a width dimension so as to be able to be disposed over the two reinforcing bars 2 as shown in FIG. ha is determined.

For example, the thickness W1 of the flow stopper 5 is 4 mm.
Smaller, preferably 0.5 to 3.0 mm, more preferably 0.5 to 2.3 mm, and still more preferably 1.6 to 2.3 mm.
A thin plate of about mm is desirable. If the thickness of the flow stopper 5 is less than 0.5 mm, it may be completely melted even though the heat radiating frame member 6 described later is arranged.
If it exceeds mm, the difference in thickness from the conventional backing tool will be reduced, and a reduction in the diameter of the joint cannot be expected.

The width ha of the metal stopper 5 is, for example, smaller than twice the gap h of the reinforcing bars 2 and 2, preferably 2 to 4 mm larger than the gap h, more preferably 2 to 3 mm.
It is desirable to make the width larger by mm. If the width ha of the flow stopper metal 5 is not larger than the gap amount h by 2 mm or more, it becomes difficult to arrange the flow stopper metal member 5 over the reinforcing bars 2 and 2, and conversely, the gap amount h If it is more than twice, the width of the flow stopper 5 increases, and the flexibility of the joint tends to be impaired.

For such a flow stopper 5, for example, any metal material capable of arc welding can be used.
For example, general carbon steels such as mild steel, high-tensile steel, stainless steel, heat-resistant steel, aluminum, and titanium, and other metal materials suitable for various kinds of welding can be used. Is mild steel.

The heat dissipating frame member 6 serves to absorb heat transferred from the molten metal M to the flow stopper 5 when the stopper 5 is fitted in contact therewith. Therefore,
As the flow stopper 5, a thin plate having a thickness W1 smaller than 4 mm can be used.

In this embodiment, the heat radiation frame member 6 has a substantially semicircular or substantially U-shaped cross section, and the flow stopper metal member 5 extending in the circumferential direction along the inner peripheral surface 6a thereof is in close contact with the heat radiation frame member 6. The figure shows an example in which a mounting groove 7 to be fitted is formed.
In this embodiment, the flow stopper 5 is fitted into the mounting groove 7 of the heat radiating frame member 6 in a fitted state, thereby being substantially flush with the inner peripheral surface 6a and integrated with the heat radiating frame member 7. FIG. In addition, to be substantially flush
This means that the difference is within 1 mm.
May be disposed so as to protrude from the inner peripheral surface 6a of the heat radiation frame member 6 by a small distance of 1 mm or more.

The heat radiating frame 6 is made of, for example,
It is desirable to use a material that has better thermal conductivity and is less likely to fuse with the flow stopper 5. For example, when the flow stopper metal 5 is made of mild steel, copper, brass, aluminum, etc. are particularly desirable, and since these materials have crushing resistance that can be used repeatedly as compared with ceramics, etc. Can be prevented, and it is particularly preferable economically. However, this does not preclude the use of other materials such as ceramics for the heat dissipation frame material.

The backing member 4 has a total thickness W2 (shown in FIG. 1) of the flow stopper metal member 5 and the heat radiation frame member 6 fitted into the mounting groove 7 of the heat radiation frame member 6 of 4 mm or more. Is desirable. If the total thickness W2 is less than 4 mm, the effect of absorbing heat transmitted to the flow stopper 5 tends to decrease. Preferably it is 4.0 to 8.0 mm, more preferably 4.0 to 8.0 mm.
It is desirable to set it to about 6.0 mm.

In this embodiment, the flow stopper 5 and the heat radiating frame 6 have holes 9a and 9b formed concentrically at least on the side opposite to the insertion opening 7 as shown in FIG. In the illustrated example, the diameter of the hole 9b of the heat radiating frame member 6 is larger than the diameter of the hole 9a of the stopper metal 5.
The holes 9a and 9b are provided with a flow stopper 5, a heat radiation frame 6
In addition to helping to dissipate heat, and helping to remove oxides during welding, it also helps to visually inspect the weld. Further, as described above, the diameter of the hole portion is different between the flow stopper metal member 5 and the heat radiation frame member 6 so that the molten metal M partially swelling from the flow stopper metal member 5 adheres to the heat radiation frame member 6. Thus, the heat radiation frame member 6 can be prevented from being fixed together with the flow stopper 5, and the detachability thereof can be enhanced.

It is desirable that the diameter of the hole 9a of the stopper metal 5 is, for example, about 3 to 6 mm so that the molten metal M does not leak. Further, the number thereof is desirably a small number in consideration of the fact that the flow stopper metal 5 is made of a small width and a thin plate.
It is preferable to arrange four or less, preferably three or less, mm pitches. In addition, such a hole part can be omitted naturally.

The backing fitting 5 is inserted into the mounting groove 7 of the heat radiating frame member 6 to form the backing member 4, and as shown in FIG. The backing material 4 is formed by the temporary fixing portion 12 in which the edge is straddled over the two reinforcing bars 2 and 2 and the flow stopper metal 5 and the reinforcing bar 2 are partially welded by, for example, manual welding. , Attached to 2. The axial overlap L between the flow stopper 5 and the reinforcing bar 2 is preferably 1 to 2 mm.

Next, in this embodiment, as shown in FIG.
The welding wire 13 of the welding torch T is inserted into the gap 3 between the end faces of the reinforcing bars 2 and 2, and the molten metal M melted by the arc of the wire 13 fills the gap 3. In this embodiment, one of the reinforcing bars 2 is grounded, and the two reinforcing bars 2 and 2 have the same ground potential via the connecting jig 20. The hardware 5 also has the ground potential.

The welding wire 13 as a welding material is inserted from the insertion opening 7 into the flow stopper 5, and, for example, by radiating an arc to the flow stopper 5, an arc is formed from the inner surface of the flow stopper 5. Welding can be started, void 3
It is useful to fill the molten metal M without any gap. In this example, a semi-automatic carbon dioxide arc welding machine for manually running the welding torch T is used, and the welding wire 13 is automatically sent out by a feeder (not shown) at a speed corresponding to the melting speed.

The molten metal M obtained by melting the molten wire 13
Are inserted from the inner surface side of the flow stopper metal 5 in the gap 3 into the insertion port 7.
As shown in FIG. 7, which is a radial cross section of the gap 3, for example, the gap is filled with the molten metal M so that the molten metal M and the end face 2 a of the rebar 2 are filled. In addition, a joint portion 10 in which the flow stopper metal 5 is integrally welded is formed, and in this example, after such a joint portion 10 is formed, the heat radiation frame member 6 of the backing device 4 is connected to the joint portion. It is one of the features that it is detached without being crushed.

As a result, only the narrow band-shaped flow stopper metal 5 remains in the joint portion 10 as shown in FIG. 5 in this example, so that the joint portion 10 can be made smaller in diameter than the conventional one. Thus, for example, the covering of concrete can be further improved. In addition, the flow stopper metal 5 remaining in the joint portion 10 can maintain the flexibility of the joint portion 10 when the width is small, especially when the width is only 2 to 4 mm larger than the gap amount h,
Good bending performance can be exhibited.

Further, since the heat radiating frame member 6 is made of a material having crushing resistance that can be used repeatedly, the radiating frame member 6 can be easily separated from the flow stopper metal member 5 by being hit with a tree or the like without being crushed at the time of removal like ceramics. The heat dissipating frame member 6 can be repeatedly used, and can be economically joined. By setting the width of the flow stopper metal to be 2 to 4 mm larger than the gap amount h,
In this case, since the molten metal does not swing directly, damage to the heat radiation frame member 6 can be effectively prevented.

Further, by using a material having a larger coefficient of thermal expansion than the flow-stopping metal 5 for the heat-radiating frame 6, for example, by forming the flow-stopping metal 5 with mild steel and the heat-radiating frame 6 with copper, after welding, Due to the difference in expansion, the width of the mounting groove 7 of the heat radiating frame member 6 becomes larger than the width of the flow stopper,
It is particularly preferable because it can be easily removed.

As described above, the embodiments of the present invention have been described in various ways. For example, the flow stopper metal 5 may be bent to a U-shape or semicircle by a finger and attached to the heat radiating frame member 6 immediately before construction on a reinforcing bar. it can. Further, the shaft to be welded is not limited to the reinforcing bar. In addition, the flow stopper 5 and the heat radiation frame 6
Can be used together, and the present invention can be modified into various modes.

[0040]

As described above, claims 1, 2 and 6
In the described invention, as a backing tool when filling the gap between the end faces of the shaft to be welded with the molten metal, the flow stopper is formed by contacting and fitting the flow stopper made of a thin band-shaped metal sheet. A heat radiating frame material that absorbs the heat of the stopper is used.

Accordingly, the flow stopper of the backing device prevents the molten metal from leaking out of the gap while releasing the heat transmitted from the molten metal to the heat radiating frame member, and thus prevents the molten metal and the shaft to be welded. Together with the end faces, these can form a joint part welded together.

After the joint portion is formed, the heat radiating frame material of the backing device is removed from the joint portion, so that a small band-shaped flow stopper metal remains at the joint portion, thereby reducing the diameter of the joint portion. Concrete covering can be further improved. In addition, since the flow stopper metal remaining at the joint makes a small width,
Smooth bending of the joint can be ensured, so that flexibility can be maintained.

According to the third aspect of the present invention, the thickness of the flow stopper metal of the backing material or the total thickness of the heat radiating frame member and the flow stopper metal is limited, so that the reinforcement for the reinforced concrete structure is provided. And it is possible to effectively prevent damage to the heat radiating frame member.

According to the fourth aspect of the present invention, the heat-radiating frame member is made of a material having crush resistance, such as copper, brass, or aluminum, which can be used repeatedly, thereby economically joining the shaft to be welded. I can do it.

According to the fifth aspect of the present invention, the flow stopper and the heat radiating frame are formed such that a hole is formed concentrically at least on a side opposite to the welding material insertion port, and a hole of the heat radiating frame is formed. Is larger than the diameter of the hole of the flow stopper, it is possible to preferably prevent the molten metal from adhering to the heat radiating frame material while improving the heat radiating property, and improve the detachability of the heat radiating frame material. sell.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a front view thereof.

FIG. 3 is an exploded perspective view of the backing device.

FIG. 4 is a side view illustrating a welding operation.

FIG. 5 is a side view of a joint obtained according to the present invention.

FIG. 6 is a side view showing an embodiment of a connecting jig.

FIG. 7 is a cross-sectional view of a gap parallel to an end face of a reinforcing bar.

FIG. 8 is a side view of a case where deformed reinforcing bars are joined according to the present invention.

FIG. 9 is a side view illustrating the covering of the concrete at the joint portion by the pressure welding method.

FIG. 10 is a side view illustrating a joint according to a conventional method.

FIG. 11 is a perspective view showing a conventional backing device.

FIG. 12 is a cross-sectional view illustrating the covering of the concrete.

[Explanation of symbols]

 2 Reinforcing Bar (Material to be Welded) 3 Air Gap 4 Backing Tool 5 Flow Stop Metal 6 Heat Dissipating Frame Material 6a Inner Peripheral Surface of Heat Dissipating Frame Material 7 Mounting Grooves 9a, 9b Hole 10 Joint

Claims (6)

[Claims] 1. A welded joint which joins the welded shaft by filling a gap of the welded shaft held with a gap between the end faces with a molten metal in which a welding material is melted using a backing tool. A method of joining shafts, wherein the backing tool has a narrow band shape that curves along the outer peripheral surface of the shaft to be welded while leaving an insertion port for a welding material and straddles the two shafts to be welded. A flow-stop fitting made of a thin metal plate, and a radiating frame material that absorbs heat transmitted from the molten metal to the flow-stop fitting by being fitted in contact with the flow-stop fitting, and welding the flow-stop fitting to a shaft to be welded. By attaching a backing tool and filling the gap with the molten metal by an arc of a welding material inserted into the gap, a joint portion in which the molten metal, the end face and the flow stopper are integrally welded is formed. After that, the backing Joining method of the welding shaft, characterized in that to remove the heat dissipation frame member from the joint portion. 2. The heat-radiating frame member has a substantially semicircular or substantially U-shaped cross section, and has an inner peripheral surface formed with a mounting groove for receiving the flow stopper fitting extending circumferentially. The method according to claim 1, wherein the flow stopper is fitted so as to substantially protrude or slightly protrude from the inner peripheral surface. 3. The flow stopper has a plate thickness of 0.5 to 0.5.
2.3 mm and has a width that is 2 to 4 mm larger than the gap amount h that is the axial length of the gap, and the total thickness of the fitted flow stopper and the heat dissipation frame material is 4 mm or more. The method according to claim 1 or 2, wherein: 4. The shaft to be welded according to claim 1, wherein said heat radiating frame member is made of a material having crush resistance, such as copper, brass or aluminum, which can be used repeatedly. Joining method. 5. The flow stopper and the heat radiating frame material,
A hole is formed concentrically at least on the opposite side to the insertion port, and the diameter of the hole of the heat radiating frame member is larger than the diameter of the hole of the flow stopper. 5. The method for joining a shaft to be welded according to any one of 4. 6. A method for joining a shaft to be welded by joining the shaft to be welded by filling the gap of the shaft to be welded held with a gap between the end faces with a molten metal in which a welding material is melted. A flow stopper comprising a narrow band-shaped metal sheet curved along the outer peripheral surface of the shaft to be welded and leaving the insertion port of a welding material, and straddling the two shafts to be welded. The metal, and the flow stopper can be fitted in contact with each other to absorb the heat transmitted from the molten metal to the flow stopper, and filled with the molten metal in the gap to join the shaft to be welded, and then the flow stopper is connected to the metal. A backing device comprising a heat-dissipating frame material to be removed.