JP2007283348A - Welding method and ring gear member welded thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding method that improves strength in a weld zone and also to provide a ring gear member welded thereby. <P>SOLUTION: A ring gear hub 1 is welded and joined by a welding method comprising a step S3 that, after a ring gear 2 and a hub 3 are butt-welded, grinds a backing material 7 for the purpose of completely removing a notched part 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a welding method in the case of butt welding a plurality of members, and a ring gear member welded using the welding method.

  In recent years, in the manufacture of members used in machines, it has been generally performed to manufacture different members and join them by welding from the viewpoint of mechanical properties required for individual parts and economical efficiency in manufacture. Yes. For example, when a ring-shaped member in which the weld line is annular is abutted and welded, in order to align the two members to be welded, the two are processed so as to have an uneven shape, There are cases where a method is employed in which fitting is performed using a backing material and this portion is welded.

In Patent Document 1, a protrusion having a square cross section at the longitudinal end is provided on the inner peripheral surface side of one ring-shaped member, and the above-described protrusion is fitted on the other ring-shaped inner peripheral surface side. There is disclosed a welding method that has recesses that fit together and welds them by fitting them together.
Japanese Patent Laid-Open No. 11-90676 (published on April 6, 1999)

However, the conventional welding method has the following problems.
That is, in the fitting position of the two members, a place deviated from the penetration range at the time of welding, for example, in Patent Document 1, a concave portion inner surface 8a deviated from the penetration range 11 becomes a structural cutout. For this reason, when an external force is applied from the outside, stress concentration occurs in the notched portion, and there is a possibility that a crack may occur starting from this portion. Similarly, in the case of welding using a backing material frequently used in such a case, a notch is formed between the backing material and the base material. For this reason, when this welding method is used in a position where a strong impact or repeated load is applied to the welded part, for example, a welded part between a ring gear and a hub or a case part in a power train of a construction machine, The ring gear hub or ring gear case may be destroyed.

  The subject of this invention is providing the ring gear member welded by this and the welding method which improves the intensity | strength in a welding part.

  A welding method according to a first invention is a welding method for welding a groove portion formed by abutting a plurality of members, and includes first to third steps. A 1st process fits the unevenness | corrugation formed with a some member, and forms a groove part. In the second step, the groove portion formed in the first step is welded. A 3rd process removes the notch formed between the some members which were not eluted in the 2nd process.

Here, in a welding method for welding a groove portion formed by abutting a plurality of members, the method includes a step of removing notches formed between members that have not been eluted in the step of welding the groove portion. ing.
In addition, the notch part said here means the structural weak part formed by the discontinuous part by mechanical and material, for example, in the case of fitting and welding the uneven part of two members, It is a portion that did not elute from each other at the fitting position, and when two members are welded using a backing material, it means a portion that did not elute from each other at the fitting portion between the backing material and each member. .

  Conventionally, in the case where members are butted and welded, in order to facilitate the positioning of each member, for example, a method using a so-called inlay fitting or a backing material in which fitting is performed using the fitting tolerance of each member. Is generally done. However, in the case of welding using a spigot fitting, a notch is formed at a part of a portion where the members are fitted. Similarly, when welding is performed using a backing material, a notch is formed in a part of the abutting member, that is, a portion where the base material and the backing material are fitted. When an external force is applied to the notched portion, stress concentration occurs in that portion, and there is a possibility that the welded portion may be broken due to generation of a crack starting from the stress concentrated portion.

Therefore, in the welding method of the present invention, the notch portion formed between the members that did not elute is removed after the portions that have been abutted by positioning the concave and convex portions formed by a plurality of members are positioned and welded. The process to do is provided.
As a result, it is possible to prevent the occurrence of a crack starting from the notch due to the stress concentration, thereby improving the reliability against fracture.
As a result, it is possible to improve the strength at the weld.

The welding method according to the second invention is the welding method according to the first invention, and in the first step, the concave portion and the convex portion in the first member having the concave portion and the second member having the convex portion. To form a groove portion.
Here, the positioning in the first step is performed by fitting the concave portion of one member (third member) and the convex portion of the other member (fourth member).
As a result, for example, even when a ring-shaped member having an annular welding line is joined, it is possible to weld the groove portion after easily positioning so that the axes of the two members coincide. Become.

  A welding method according to a third invention is the welding method according to the first invention, wherein, in the first step, a fifth member is formed in a recess formed in at least one of the third member and the fourth member. To form a groove portion.

Here, the positioning in the first step is performed by using another member (fifth member), a so-called backing, in the recess formed in at least one of the two members (third member / fourth member) serving as the base material. This is done by fitting the materials together.
Thereby, after positioning two members easily, it becomes possible to weld a groove part. Furthermore, when a backing material having a melting point lower than that of the two members serving as the base material is used, it is possible to secure the amount of penetration of the groove bottom and avoid poor fusion. As a result, the strength of the welded portion can be improved.

A welding method according to a fourth invention is the welding method according to any one of the first to third inventions, further comprising a fourth step of removing the weld bead formed in the second step. ing.
Here, there is further provided a step of removing the belt-like bulge formed in the welded portion, that is, the weld bead, and smoothing the toe portion which is a contact point between the weld bead and the base material.

Here, when an impact is applied directly above the weld bead, stress concentration occurs at the toe. At this time, cracks may occur starting from the stress concentration portion, and the welded portion may be destroyed.
Therefore, in the welding method of the present invention, the two members are butted and welded to remove the notch, and then the weld bead formed in the weld is removed to smooth the toe.
Thereby, since the generation | occurrence | production of the crack starting from the toe part by stress concentration can be prevented, the reliability with respect to a fracture | rupture can further be improved.
As a result, even a welded portion that receives a strong impact load or repetitive load on the surface of the member can ensure strength that can withstand destruction.

A welding method according to a fifth aspect is the welding method according to any one of the first to fourth aspects, wherein the second step is performed by arc welding.
Here, the welding in the second step is performed by arc welding.
Thereby, even if it is welding by arc welding, a high-quality welded part without a vulnerability can be provided by the welding method mentioned above. As a result, it is possible to weld and join with general equipment having high versatility, so that it is possible to perform welding at low cost while suppressing initial costs.

A ring gear member according to a sixth invention is a ring gear member used in a construction machine, and is welded and joined by the welding method according to any one of the first to fifth inventions.
Here, the ring gear member is formed by the above-described welding method.
The ring gear member referred to here includes a ring gear hub or a ring gear case obtained by joining a ring gear and a hub or case.

Here, the ring gear member is used, for example, in a final drive or a turning portion of a hydraulic excavator that is one of construction machines. And, for example, in the final drive of a hydraulic excavator, it transmits the rotational force from the shaft and directly receives the impact of rocks crushed during traveling from the outside, so it receives a very strong impact force and repeated load It is.
Thereby, even in a situation where a very strong impact force or repeated load is received, it is possible to avoid the occurrence of a strength problem by using the ring gear member welded and joined by the welding method according to the present invention. it can.

A ring gear member according to a seventh invention is a ring gear member according to the sixth invention, and is a welded structure of a steel member and a cast iron member.
Here, the ring gear member is a welded structure in which a steel member and a cast iron member are welded together by the above-described welding method.

  As a result, even in the welding and joining of steel members and cast iron members that are generally used in ring gear members, it is possible to avoid the occurrence of strength problems by welding and joining using the welding method according to the present invention. can do.

  According to the welding method according to the first invention, it is possible to improve the strength in the welded portion.

[First Embodiment]
A method for welding the ring gear hub (ring gear member) 1 according to the present embodiment will be described below with reference to FIGS.
[Configuration of Ring Gear Hub 1]
A ring gear hub 1 according to an embodiment of the present invention is used, for example, in a final drive (not shown) of a hydraulic excavator (not shown) which is a kind of construction machine. A third member 2 and a hub (fourth member) 3 are joined together by arc welding.

  The ring gear 2 is an annular member made of steel (S48C) as shown in FIG. 1 (a) and FIG. 1 (b), and has an inner peripheral surface side as shown in FIG. 2 (a). A recess 4 is provided on the tip end side (the side to be abutted with the hub 3). And the internal peripheral surface 4a of the part in which the recessed part 4 of the ring gear 2 is provided has an internal diameter larger than the internal peripheral surface 4b of the part in which the recessed part is not provided.

  The hub 3 is made of vermicular cast iron (FCV410) or spheroidal graphite cast iron (FCD450), and as shown in FIGS. This is a shape having a part and a disk part having a larger diameter than the above-mentioned annular part on the other side. Similarly to the ring gear 2, the hub 3 is also provided with a recess 5 on the tip side on the inner peripheral surface side (the side facing the ring gear 2), as shown in FIG. The inner peripheral surface 5a of the portion where the concave portion 5 is provided has a larger inner diameter than the inner peripheral surface 5b of the portion where the concave portion 5 is not provided.

[Welding method of ring gear hub 1]
The welding connection between the ring gear 2 and the hub 3 in the ring gear hub 1 of the present embodiment is performed by a welding method according to the flowchart shown in FIG.
In step S1, the ring gear 2 and the hub 3 to be joined are positioned. Specifically, as shown in FIG. 2 (b), the hub 3 is fitted so that the backing material (fifth member) 7 is fitted into the recess 4 in the ring gear 2 and is fitted to the backing material 7. This is done by arranging the concave portion 5. As a result, the backing material 7 is fitted to the stepped portions having large inner diameters of the ring gear 2 and the hub 3, and the positions of the backing material 7 are fixed coaxially. In the welding joint of this embodiment, the backing material 7 employs a member having a melting point lower than that of the ring gear 2 and the hub 3. Thereby, the poor fusion in the backing material 7 can be avoided, and the strength of the welded portion 13 shown in FIG. 2 (d) can be improved.

  In step S2, the ring gear 2 in which the positioning is formed in step S1 and the hub 3 are welded. Specifically, as shown in FIG. 2B, a V-shaped groove portion 8 formed on the outer peripheral surface side of the position where the ring gear 2 and the hub 3 are abutted with each other is shown in FIG. As shown, the weld metal 9 is built up to join them together. A broken line around the groove portion 8 indicates a range in which the weld metal 9 is melted into the ring gear 2 and the hub 3 which are base materials.

  In step S3, the notch 10 where stress concentration occurs is removed. Here, the notch is a structural discontinuous portion in which the members do not elute and are not integrated, and in this embodiment, the weld metal 9 indicated by the broken line in FIG. This corresponds to the notch 10 (see FIG. 2C) generated at the boundary between the ring gear 2 and the backing material 7 and the hub 3 and the backing material 7 outside the range in which the metal melts. Specifically, the inner peripheral surface side welded portion 13a is formed by cutting a portion of the backing material 7 so that the cutout portion 10 is completely removed as shown in FIG. Thereby, generation | occurrence | production of the crack which started from the notch part 10 can be suppressed.

  In step S4, the weld bead 11 formed by the welding performed in step S2 is removed. Here, as shown in FIG. 2 (c), the weld bead 11 is a weld metal 9 welded to the groove portion 8 rather than the outer peripheral surface of the ring gear 2 and the hub 3 as a base material. A boundary portion between the surface of the base material 2 and 3 and the weld bead 11 is referred to as a toe portion 12. When a strong impact is applied directly above the weld bead 11, stress concentration occurs in the toe portion 12, and there is a possibility that a crack starting from the toe portion 12 may occur. Therefore, in step S4, as shown in FIG. 2 (d), the weld bead 11 is scraped off and smoothed so that there is no step at the toe portion 12 to form the outer peripheral surface side weld portion 13b. Thereby, generation | occurrence | production of the crack which started from the toe part 12 can be suppressed.

The ring gear hub 1 according to the present embodiment can perform welding joint with improved strength by removing the fragile portion where stress concentration occurs by performing the welding joint through the processes as described above.
[Example 1]
In order to confirm the effect of the process of removing the backing material 7 according to the present invention, as shown in FIG. 4, the vehicle body of the construction machine in which the ring gear hub 1 is mounted on the welded portion 13 immediately above the welded portion 13. An impact load test was repeated 100 times by adding an impact load of 59.9 t, which is 2.8 times the weight, with the test body with the backing material 7 left and the test body with the backing material 7 removed.

As a result, the maximum principal stress generated in the welded portion 13 is 35 kg / mm ² for the test body with the backing material 7 left, and 22 kg / mm ² for the test body with the backing material 7 removed. It was confirmed that a large stress was generated in the test body that remained as compared with the test body from which the backing material 7 was removed. Thus, it was confirmed that the removal of the backing material 7 is more advantageous for the strength against the impact load.

[Example 2]
In order to confirm the effect of the process of removing the backing material 7 according to the present invention, a fatigue test was further performed. As the fatigue strength of the ring gear hub 1 is mainly caused by torsional stress, in this embodiment, the torsional fatigue test is performed on the test body from which the backing material 7 is left and the test body from which the backing material 7 is removed. Went.

  As a result, an SN curve as shown in FIG. 5 is obtained, and fatigue failure occurs in the test body with the backing material 7 left with a smaller stress S than the test body with the backing material 7 removed. I was able to confirm. Further, it was confirmed that the fatigue limit at which the fracture did not occur even when the number of repetitions N was further increased was smaller in the test body in which the backing material 7 was left than in the test body in which the backing material 7 was removed. Thereby, it has confirmed that the direction which removed the backing material 7 was advantageous with respect to fatigue strength.

[Features of welding method of ring gear hub 1]
(1)
In the ring gear hub 1 welding method of the present embodiment, after the ring gear 2 and the hub 3 are abutted and welded together, a step S3 for cutting the backing material 7 to completely remove the notch 10 is provided. Yes.

Thereby, since the notch part 10 which stress concentration generate | occur | produces can be removed, generation | occurrence | production of the crack starting from the notch part 10 can be suppressed.
As a result, it is possible to improve the strength in the welded portion 13.
(2)
In the welding method of the ring gear hub 1 of the present embodiment, in the positioning step S1, the positioning of the ring gear 2 and the hub 3 to be joined is performed with respect to the concave portion 4 of the ring gear 2 as shown in FIG. This is done by fitting the backing material 7 and disposing the concave portion 5 of the hub 3 so as to fit the backing material 7.

Thereby, positioning with the ring gear 2 and the hub 3 can be performed easily.
(3)
The ring gear hub 1 welding method according to the present embodiment further includes a step 4 in which the weld bead 11 is scraped off and smoothed so that there is no step at the toe end 12.
Thereby, since the toe portion 12 where stress concentration occurs can be removed and the occurrence of cracks starting from the toe portion 12 can be prevented, the reliability against fracture can be further improved.

(4)
In the ring gear hub 1 welding method of the present embodiment, the ring gear 2 and the hub 3 are integrally joined by arc welding.
Thereby, even if it weld-joins with general equipment with high versatility, it becomes possible to improve the intensity | strength of a welding part. As a result, the initial cost can be reduced.

[Second Embodiment]
A method for welding a ring gear case (ring gear member) 21 according to another embodiment of the present invention will be described below with reference to FIGS. 3 and 6 and 7.
[Configuration of Ring Gear Case 21]
The ring gear case 21 according to the present embodiment is used for, for example, a final drive (not shown) of a hydraulic excavator (not shown) which is a kind of construction machine, as with the ring gear hub 1 of the first embodiment. A ring gear (first member) 22 and a case (second member) 23 shown below are integrally joined by arc welding.

  As shown in FIG. 6, the ring gear 22 is an annular member made of steel (S48C), and as shown in FIG. On the side), a recess 24 is provided. The inner peripheral surface 24a of the portion of the ring gear 22 where the concave portion 24 is provided has a larger inner diameter than the inner peripheral surface 24b of the portion where the concave portion 24 is not provided.

  The case 23 is made of vermicular cast iron (FCV410) or spheroidal graphite cast iron (FCD450), and as shown in FIG. 6, one is an annular part having the same diameter as the ring gear 22 and the other is the aforementioned annular part. It is a shape which has a larger diameter disk part. As shown in FIG. 7 (a), the case 23 is provided with a convex portion 25 at the inner peripheral surface side tip (side to be abutted against the ring gear 22), and as shown in FIG. 7 (b), The convex portion outer peripheral surface 25a and the concave portion inner peripheral surface 24a of the ring gear 22 are in contact with each other to form a fitting portion 26.

[Welding method of ring gear case 21]
The welding connection between the ring gear 22 and the case 23 in the ring gear case 21 of the present embodiment is performed by a welding method according to the flowchart shown in FIG. Since the removal of the weld bead 31 in step S4 is the same as that of the ring gear hub 1 in the first embodiment, the description thereof is omitted here.

In step S1, the ring gear 22 to be joined and the case 23 are positioned. Specifically, as shown in FIG. 7B, the convex portion 25 in the case 23 is fitted into the concave portion 24 in the ring gear 22.
In step S2, the ring gear 22 in which the positioning is formed in step S1 and the case 23 are welded. Specifically, as shown in FIG. 7B, the V-shaped groove portion 28 formed on the outer peripheral surface side at the position where the ring gear 22 and the case 23 are brought into contact with each other is shown in FIG. As shown, the weld metal 29 is built up to join them together. A broken line around the groove portion 28 indicates a range in which the weld metal 29 melts into the ring gear 22 and the case 23 which are base materials.

  In step S3, the notch 30 where stress concentration occurs is removed. In the present embodiment, a notch 30 (see FIG. 7C) is generated at the boundary between the ring gear 22 and the case 23 outside the range in which the weld metal 29 indicated by the broken line in FIG. Specifically, the inner peripheral surface side welded portion 33a is formed by cutting so as to include the fitting portion 26 so that the cutout portion 30 is completely removed as shown in FIG. 7 (d). is doing. Thereby, generation | occurrence | production of the crack which started from the notch part 30 can be suppressed.

The ring gear case 21 of the present embodiment can perform welding joint with improved strength by removing the fragile portion where stress concentration occurs by performing the various processes as described above.
[Features of welding method of ring gear case 21]
(1)
In the welding method of the ring gear case 21 of this embodiment, after the ring gear 22 and the case 23 are abutted and welded together, a step S3 for cutting the fitting portion 26 to completely remove the notch portion 30 is provided. Yes.

Thereby, since the notch part 30 in which stress concentration occurs can be removed, the generation of cracks starting from the notch part 30 can be suppressed.
As a result, similarly to the ring gear hub 1 in the first embodiment, the strength in the welded portion 33 can be improved.
(2)
In the welding method of the ring gear case 21 of the present embodiment, in the positioning step S1, the positioning of the ring gear 22 and the case 23 to be joined is performed with respect to the concave portion 24 of the ring gear 22 as shown in FIG. This is done by fitting the convex portion 25 of the case.

Thereby, like the welding method of the ring gear hub 1 in 1st Embodiment, positioning with the ring gear 22 and the case 23 can be performed easily.
(3)
The method for welding the ring gear case 21 of the present embodiment further includes step 4 in which the weld bead 31 is scraped and smoothed so that there is no step at the toe portion 32 to form the outer peripheral surface side welded portion 33b.

Thereby, like the welding method of the ring gear hub 1 in the first embodiment, it is possible to remove the toe portion 32 where stress concentration occurs and to prevent the occurrence of cracks starting from the toe portion 32. Therefore, the reliability against destruction can be further improved.
(4)
In the welding method of the ring gear case 21 of the present embodiment, the ring gear 22 and the case 23 are integrally joined by arc welding.

Thereby, similarly to the welding method of the ring gear hub 1 in the first embodiment, it is possible to improve the strength of the welded portion even if welding is performed with general equipment having high versatility. As a result, the initial cost can be reduced.
[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

(A)
In the welding method of the ring gear hub 1 and the ring gear case 21 of the above-described embodiment, the example in which step S4 for removing the weld beads 11 and 31 is performed has been described. However, the present invention is not limited to this.
Even if the weld bead is not removed, the same effect as in the first and second embodiments can be obtained in that the strength is improved because the notch in the weld is removed.

However, when the ring gear hub and ring gear case used in locations where a strong impact is applied directly above the weld bead, the weld bead must be removed to prevent stress concentration at the toe. It is desirable to do.
(B)
In the method for welding the ring gear case 21 of the above-described embodiment, the example in which the concave portion 24 of the ring gear 22 and the convex portion 25 of the case 23 are fitted and positioned in the positioning step S1 has been described. However, the present invention is not limited to this.

For example, it is possible to weld and join both the ring gear with the convex portion and the case with the concave portion. Also in this case, an effect similar to that of the second embodiment, in which the ring gear and the case can be easily positioned, can be obtained.
In addition, when an impact load test was performed on a joint portion between the two (the ring gear has a concave portion and the case has a convex portion and the ring gear has a convex portion and the case has a concave portion), the maximum principal stress is 22 kg / From the results similar to those of Example 1 of mm ^2, the same effects as those of the second embodiment can be obtained with respect to strength.

(C)
In the welding method of the ring gear case 21 of the above embodiment, the convex outer peripheral surface 25a of the case 23 and the concave inner peripheral surface 24a of the ring gear 22 are in contact with each other in the positioning step S1, as shown in FIG. An example of such a fitting shape has been described. However, the present invention is not limited to this.

For example, even if the groove shape of both members as shown in FIG. 8 (a), the mutual positioning can be easily performed as shown in FIG. 8 (b), and the same effect as in the second embodiment described above. Can be obtained.
(D)
In the welding method of the ring gear hub 1 of the above embodiment, the example in which the backing material 7 is a member having a melting point lower than that of the ring gear 2 and the hub 3 as the base material has been described in the positioning step S1. However, the present invention is not limited to this.

Even if the backing material is not a member whose melting point is lower than that of the ring gear and the hub as the base material, the backing material can be easily positioned by being fitted to the base material. Similar effects can be obtained.
However, it is desirable to use a backing material having a melting point lower than that of the base material because it has the effect of avoiding poor fusion and improving the strength of the weld.

(E)
In the method for welding the ring gear hub 1 and the ring gear case 21 of the above embodiment, an example in which both annular members are welded and joined has been described. However, the present invention is not limited to this.
For example, even when the welding method according to the present invention is applied in the welding and joining of steel plates, the same effect as the above embodiment can be obtained.

  According to the present invention, since the strength in the welded portion can be improved, the present welding method can be widely applied when reliability such as fracture is required for the welded portion.

(A) and (b) are the external views of the ring gear hub weld-joined by the welding method which concerns on one Embodiment of this invention. (A) is sectional drawing which showed the groove shape of the ring gear and hub of FIG. (B) is sectional drawing which showed the state which fitted the backing material to the ring gear and hub of FIG. (C) is sectional drawing which showed the state which piled up the weld metal in the groove part of FIG.2 (b). (D) is sectional drawing which showed the state which removed the notch part and welding bead shown in FIG.2 (c). The flowchart which shows the welding method of the ring gear hub and ring gear case which concern on one Embodiment of this invention. The schematic diagram of the impact load test done in order to confirm the effect concerning the present invention. The graph which showed the result of the torsional fatigue test done in order to confirm the effect which concerns on this invention. The external view of the ring gear case weld-joined by the welding method which concerns on other embodiment of this invention. (A) is sectional drawing which showed the groove shape of the ring gear and case of FIG. (B) is sectional drawing which showed the fitting state of the ring gear and case of FIG. (C) is sectional drawing which showed the state which piled up the weld metal in the groove part of FIG.7 (b). (D) is sectional drawing which showed the state which removed the notch part and welding bead shown in FIG.7 (c). (A) is sectional drawing which showed the groove shape of the base material in other embodiment. (B) is sectional drawing which showed the fitting state of both the members shown to Fig.8 (a).

Explanation of symbols

1 Ring gear hub (ring gear member)
2 Ring gear (third member)
3 Hub (fourth member)
4 recessed part 4a inner peripheral surface 4b inner peripheral surface 5 recessed part 5a recessed part inner peripheral surface 5b recessed part outer peripheral surface 7 backing material (fifth member)
8 Groove part 9 Weld metal 10 Notch part 11 Weld bead 12 Toe part 13 Weld part 13a Inner peripheral surface side weld part 13b Outer peripheral surface side weld part 21 Ring gear case (ring gear member)
22 Ring gear (first member)
23 Case (second member)
24 concave portion 24a inner peripheral surface 24b inner peripheral surface 25 convex portion 25a convex outer peripheral surface 26 fitting portion 28 groove portion 29 weld metal 30 notch portion 31 weld bead 32 toe portion 33 weld portion 33a inner peripheral surface side weld portion 33b Outer peripheral surface side welded portion S Step

Claims (7)

A welding method for welding a groove formed by abutting a plurality of members,
A first step of fitting the irregularities formed by the plurality of members to form the groove portion;
A second step of welding the groove portion formed in the first step;
A third step of removing notches formed between the plurality of members that did not dissolve in the second step;
Welding method with. In the first step, the groove portion is formed by abutting the concave portion and the convex portion in the first member having the concave portion and the second member having the convex portion,
The welding method according to claim 1. In the first step, the groove portion is formed by fitting a fifth member into a recess formed in at least one of the third member and the fourth member.
The welding method according to claim 1. A fourth step of removing the weld bead formed in the second step;
The welding method according to any one of claims 1 to 3. The second step is performed by arc welding.
The welding method according to any one of claims 1 to 4.   The ring gear member used with the construction machine weld-joined by the welding method of any one of Claim 1 to 5. A welded structure of a steel member and a cast iron member.
The ring gear member according to claim 6.

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