JPS6036873B2 - gas welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas welding method, and particularly to a gas welding (or compression) method using oxygen-acetylene gas.

In this type of gas welding method, objects such as a pair of reinforcing bars to be welded are joined together, and a nozzle for spouting a mixed gas of acetylene and oxygen is arranged around this joint (part to be welded). Generally, the above-mentioned mixed gas is sprayed onto the part to be welded from this nozzle.

In this case, the following problems arise.

In other words, if the above-mentioned joint is insufficient and there is even a small gap, welding will be performed with oxygen in the atmosphere penetrating this gap, so the resulting welded part will be welded without oxygen. If the welded parts are taken in (oxidized), the pair of objects may not be welded at all, or the strength of the welded part may be so weak that it may easily break when stress is applied. For this reason,
Even in the early stages of welding, it is necessary to apply a considerable amount of force to the workpiece to eliminate the gap at the joint, but even with pressure applied in this way, it is impossible to completely eliminate the gap.
It is not possible to prevent the formation of an oxide film at the weld. Also,
Another problem is that the surface of the object to be welded is often already oxidized by atmospheric oxygen (this is especially true when the object is fused and then welded again at the fused location). be.

), before welding, the oxide film on the surface of the object must be sufficiently removed by polishing means such as a sander. On the other hand, a nozzle is provided with a spout for the mixed gas and a spout for only acetylene gas side by side, and the acetylene gas from the latter spout forms a reducing flame sphere for the part to be welded;
Devices that attempt to prevent oxidation as described above are conceivable.

However, in this case, simply spraying acetylene gas will easily mix with the mixed gas, so it will be the same as spraying a mixed gas containing too much acetylene, and will not solve the problem. As a result of intensive study, the inventor has found that
In particular, by skillfully devising the gas ejection method, we have discovered a method that can effectively eliminate all of the above problems.
This has led to the present invention.

That is, the gas welding method according to the present invention applies a mixed gas of a fuel gas (for example, acetylene gas) and an oxidizing gas (for example, oxygen gas) to a welding position of an object to be gas-welded (for example, a pair of reinforcing bars). At the same time as spraying, a gas consisting essentially only of the fuel gas is directly sprayed onto a position to be welded that is different from the spraying position, and at this time, this gas is not substantially mixed with the mixed gas. It is characterized in that it is sprayed after being prepared.

Therefore, according to the method of the present invention, since the gas mainly consisting of fuel gas is sprayed at a different position from the above-mentioned mixed gas without mixing, the reducing flame sphere caused by this gas is sufficiently generated in the part to be welded. This effectively blocks the influence of oxygen and completely prevents the formation of oxide films or oxides that may occur during welding.

As a result, not only can a welded part with sufficient strength be formed, but even if there is a gap between the objects during welding, this gap is filled with the reducing flame, so no problem occurs. Therefore, there is no need to apply initial pressure to the object during welding, and work efficiency is greatly improved. In addition, even if an oxide film already exists on the surface of the object before welding, this oxide film is reduced by the reducing flame caused by the fuel gas and disappears, so the removal work of the oxide film can be omitted, and this can also be done during welding. This contributes to improved workability and pacing. DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples in which the present invention is applied to oxygen-acetylene gas welding or pressing will be described in detail below with reference to the drawings.

First, with reference to FIGS. 1 to 7, the overall configuration of a gas welding apparatus used in the gas welding method according to this example will be explained.

This device consists of a blowpipe part 1 and a nozzle part (or burner part) 2, and an oxygen gas introduction pipe 3 and an acetylene gas introduction pipe 4 are provided at the tip of the blowpipe part 1, and each gas from these introduction pipes is are mixed with each other in the merging pipe section 5 to form the blowpipe 6.
from there to the nozzle section 2. The acetylene gas from the inlet pipe 4 is branched in the grip part 36 of this device, one part is mixed with the oxygen gas, and the other part is led to the nozzle part 2 through another blowpipe 7.

In addition, 8 in the figure is a control valve (nut) for acetylene gas, 9 is a control valve (nut) for oxygen gas, and 1 is a control valve (nut) for oxygen-acetylene mixed gas.
Both are configured as well-known screw-in valves. The blowpipe 6 for mixed gas is further branched into U-shaped branch pipes 11 and 12 of the nozzle section 2, respectively, and communicated with nozzles 13 and 14, and 15 and 16, which are integrated with each branch pipe. On the other hand, the acetylene gas blowpipe 7 is branched into small pipes 17 and 18 before the nozzle part 2, and after passing through the side walls of the branch pipes 11 and 12, respectively,
5 and is guided to its tip. The nozzle portion 2 can be removed from the blowpipe 7, 6 by loosening the nuts 38, 39, and can be replaced with a nozzle suitable for the size of the object. Here, it is important that the nozzle section 2 is constructed as shown in FIGS. 8 to 10.

First, each nozzle 13 to 16 is connected to an object 19 to be welded.
The parts to be welded 20' (for example, reinforcing bars) are arranged radially symmetrically in all directions, and each tip has a part to be welded 20'.
at least two mixed gas outlets 21 along the circumferential direction of the
and 22, 23 and 24, 25 and 26, 27 and 28
are formed obliquely from the center axis of the nozzle. The mixed gas 29 from each of these jetting ports is evenly sprayed at eight locations on the part to be welded 201, so that heating by the gas flame can be uniformly performed. In addition, during gas welding, each nozzle is arranged so that the center of the object 19 is located at the intersection point P of the central axes of the nozzles 13 to 16, and a perpendicular line from the center and an extension line of the blowpipe 6 are It is preferable to define the relationship between each layer so that they intersect orthogonally to each other. In other words,
This is because it is possible to ensure uniform distribution of the mixed gas during welding. In addition to the above-mentioned nozzle arrangement, a notable configuration is that the above-mentioned small tubes 17 and 18 are mutually 18
The mixed gas is guided through the nozzles 14 and 15 facing each other at an angle of 0 degrees to their tips, and the mixed gas jet ports 23 and 2 of each nozzle
4, 25, and 26 are closed as acetylene gas jet ports 30 and 31, respectively. These jet ports 30 and 31 are therefore capable of spraying the acetylene gas 32 onto the object 19 in directions opposite to each other in the direction of its distortion. FIGS. 9 and 10 show each of the above-mentioned jet ports in more detail. Note that FIG. 11 schematically shows the gas flow path in the blowpipe. Next, a method of welding using the gas welding (or press) apparatus configured as described above will be explained.

First, as shown in FIG. 12, welding parts 20 of objects to be welded together, for example, a pair of reinforcing bars 19a and 19b.
beard.

At this time, since the two parts to be welded are cut diagonally in order to improve the heating efficiency during melting, a certain interval 33 exists there. The existence of this gap 33 poses no problem for reasons explained in detail later, and it is completely unnecessary to apply initial pressure. What is particularly noteworthy in the state before the start of welding as shown in FIG.
, 19b (particularly the surface to be welded) already has an oxide film, it is not necessary to remove it in advance with a sander or the like as in the conventional case. 13A and 13
As shown in Figure B, a pair of reinforcing bars 19a, 19 are inserted by each nozzle.
It is set so as to surround the welded part (or joint part) 20 of b, and an appropriate amount of acetylene gas 32 is ejected from each nozzle together with oxygen-acetylene mixed gas 29.

When the temperature of the welded part 20 increases due to the gas flame, the reinforcing bar 1
9a and 19b are compressed by, for example, hydraulic drive, and welding is performed in this state, so that a welded part 35 that rises uniformly around the entire circumference is created as shown in Fig. 14, and both reinforcing bars are completely welded. be able to. During this welding,
As clearly shown in FIGS. 13A and 13B, the mixed gas 29 is sprayed almost evenly around the entire circumference of the object, and at the same time, the acetylene gas 32 is sprayed at a position different from this spraying position.
It is extremely important to spray the acetylene gas directly and to prevent this acetylene gas from mixing with the mixed gas 29 during spraying. Therefore, the acetylene gas 32 is
This results in sufficient contact with the gap 33 and its vicinity. Furthermore, as clearly shown in FIG. 13B, since the mixed gas 29 from each nozzle is sprayed at the angle relationship shown in the figure, the mixed gas flows mix with each other after colliding with the circumferential surface of the object, creating a turbulent flow. 34 is generated, and the mixed gas flow due to this turbulence spreads along with the reducing gas in the direction along the axis of the object as shown by the dashed line in FIG. 13A. This is an effective phenomenon in shielding the part to be welded from atmospheric oxygen. After welding is performed in this manner, the welded portion 35 is polished or the like as required to flatten the surface of the product 37 as shown in FIG. 15.

As can be understood from the above, according to the welding method (gas pressure bushing method) of this embodiment, during welding work, the reinforcing bar 19
As described above, the mixed gas 29 is evenly applied to the two parts to be welded between a and 19b, so that uniform heating can be performed.

Furthermore, even if there is a gap between the joints of both reinforcing bars 19a and 19b, the area of the reducing flame that spans the two parts to be welded will be sufficiently expanded by the jetting of acetylene gas from the jetting ports 30 and 31. As a result, the part to be welded 2
The oxidation reaction at 0 is inhibited, and the formation of an oxide film or oxide can be effectively prevented. This anti-oxidation effect is extremely good because the acetylene gas is ejected at a position different from the ejecting position of the mixed gas and is ejected from the nozzles 14 and 15 in opposite directions. The effect of ejecting the above acetylene gas in opposite directions is that a kind of turbulent flow occurs evenly due to the collision of the acetylene gases, which prevents localization of the gas flame and reduces the gas flame. Contributes to expanding the flame area. Therefore, in the above method, there is no need to apply initial pressure during welding (i.e.,
Even if the gap 33 exists, there is no problem and the welding workability will be improved.

Moreover, even if an oxide film exists on the surface of the reinforcing steel before welding, this oxide film will be reduced during welding by the effective supply of acetylene gas 32, and will not remain in the welded part 35. For this reason, there is no need to remove the oxide film in advance. In the welded parts obtained based on the above-described method, no surface properties or appearance peculiar to oxides were observed, and it was confirmed that carbon was present or adhered everywhere.

This means that the acetylene-oxygen weldability is sufficient while the above-mentioned reducing atmosphere acts effectively during welding. It was also confirmed that the welded portion had sufficient strength and did not pose any problems in tensile tests and bending tests. Note that the positions of the acetylene gas jet ports 30 and 31 are very important from the above-mentioned point of view, but according to this embodiment, since they are formed integrally with the nozzles 14 and 15 themselves, their position accuracy cannot be improved. Easy to take out. In other words, the nozzle 14,
15, and then fixed to the tip surfaces of the nozzles 14, 15, or even if the tips 34 are integrated with the nozzles 14, 15, Machining is easy and precise. In addition, the nozzle structure used in this example allows for clear visual inspection of the welded part of the object by appropriately arranging each nozzle (e.g., an acetylene gas outlet is integrated into the nozzle). This makes it possible to perform welding with good workability and safety.

Furthermore, since this welding device can achieve a uniform heating effect,
It is not necessary to perform operations such as rotating the object to equalize the heating temperature, which also greatly contributes to improving work efficiency.

FIGS. 16 and 17 show modifications of the nozzle structure described above.

In this example, the small tubes 17, 18 for the acetylene gas mentioned above are
is guided along the outer surface of each branch pipe 11, 12 of the nozzle portion 2 to the tips of the nozzles 14, 15.

Even with this configuration, the same oxidation prevention effect as in the first embodiment described above can be obtained by directing the jet ports of the small tubes 17 and 18 at the nozzle tips toward the welded part. Further, since each of the small tubes 17 and 18 is integrated with the nozzle, the object can be easily observed during welding, and does not interfere with the work. FIG. 18 shows yet another welding device, which differs from the above-mentioned example in that the grip portion 6 is provided in the same direction as the blowpipe 6 (that is, it is not bent). . This linear welding device may be appropriately selected and used depending on the place where it is used. Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the number of each nozzle mentioned above, the number of mixed gas and acetylene gas jetting ports, and the positions can be variously changed. Further, the type of gas to be used is not limited to those described above as long as it can be used for gas welding or compression. Further, the object to which the present invention is applied may be other than the above-mentioned longitudinal material such as reinforcing steel, and the ejection method of each gas, the structure of the nozzle, etc. can be changed as appropriate depending on the type of object.

[Brief explanation of the drawing]

The drawings show the implementation of the present invention, and FIG. 1 is a plan view of the gas welding device, FIG. 2 is a back view of the same device, FIG. 3 is a front view of the same device, and FIG. 4 is a plan view of the same device. The rear view of the device, FIG. 5 is a right side view of the device, FIG. 6 is a left side view of the device, FIG. 7 is a perspective view of the device, and FIG. 8 is a part of the nozzle part (burner part). 9 is a sectional view of the nozzle, FIG. 10 is a front view of the tip of the nozzle, FIG. 11 is a schematic flow path diagram of gas in the blowpipe, FIGS. 12, 13A, and 13B. , 14th
15 is a diagram showing each stage of welding work, FIG. 16 is a plan view of a part of a nozzle part (burner part) according to another example, and FIG. 17 is a front view of the nozzle tip of the same nozzle part, 1st
FIG. 8 is a front view of a gas welding device according to yet another example. In addition, in the symbols shown in the drawings, 1... blowpipe part, 2... nozzle part (burner part), 6, 7...
...Blowpipe, 11, 12... Branch pipe, 13,
14, 15, 16... Nozzle, 17, 18... Small tube, 1
9...Object, 20...Part to be welded, 2
1-28... Mixed gas outlet, 29... Mixed gas, 30, 31. ．． ...・Acetylene gas outlet, 3
2...Acetylene gas, 33...Gap, 3
4...Turbulent gas, 35... ··welded part. It is. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13A Figure 13B Figure 14 Figure 15 Figure 16 Figure 17 Figure 18

Claims (1)

[Claims] 1. Spraying a mixed gas of fuel gas and oxidizing gas to a welding position of the object to be gas welded, and at the same time spraying substantially only the fuel gas to a welding position other than this spraying position. A gas welding method characterized in that a gas consisting of: is directly sprayed, and the gas is sprayed in a state in which the gas is not substantially mixed with the mixed gas.