JPS6124108B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc welded joint in which two members are butt welded with or without a backing metal.

In arc welding, the metal base metals to be joined and the welding rod are melted together by arc heat, and the metal base metals are joined together. The suitability of the depth is an important factor that determines the quality of welding.

However, in actual welding work, it is generally difficult to confirm whether or not this penetration depth is an appropriate amount. For this reason,
Welding is performed so that a surplus is also generated on the back side of the welded part, and the welding conditions are adjusted while visually checking the surplus. However, in this case, the molten metal that has reached the back side of the welded part is likely to partially melt down at the weld line, creating a hole, especially when welding the entire circumference of an annular member, at the start and end of the weld. Since the parts are wrapped to some extent, the burn-through is more likely to occur in the wrapped parts.

In order to solve this problem, it is conceivable to switch the welding conditions at the lapped portion and perform welding under more relaxed conditions. However, in this case, a device is required to switch and control such conditions, which complicates the welding equipment, resulting in increased equipment and maintenance costs, and the failure rate is correspondingly high.
A problem arises in which the device operating rate decreases.

Separately, controlling the welding conditions can be made easier to some extent by using a device that performs arc welding using pulsed current, but even in this case, the same problems as with the above-mentioned devices arise, such as the device being complicated and expensive. .

Furthermore, the base material is likely to be melted and welded to a depth greater than the desired value, which consumes additional welding power and becomes a factor in increasing processing costs.

The present invention was developed against the background of the above circumstances, and its purpose is to facilitate the setting and control of optimal welding conditions, enable inspection and confirmation of welding quality, and provide a simple method. An object of the present invention is to provide an arc welding method that can be performed using a welding device.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

1 to 4 show an arc welded joint that is arc welded by the method of the present invention, in which a first member 10 is in the form of a flat plate, and a second member 12 is also in the form of a flat plate and has the same thickness. A third member 14 which is abutted at one end and bent into a substantially L-shape is welded in close contact with the back side of the abutting portion of the first and second members 10 and 12 (however, as shown in FIGS. In Figure 4, the welded portion is shown in a state before welding for convenience of explanation of the welding procedure). First member 1
0 and the second member 12 have end surfaces to be joined that are perpendicular to both the front and back surfaces (that is, are not beveled), and are butted in close contact at these end surfaces. Furthermore, shallow rectangular notches 16 are provided at regular intervals in the abutting end of the second member 12, which extends along the abutting end surface in a state before welding.

A third member 14 located on the back side of the first member 10 and the second member 12 is connected to the first member 10 and the second member 1.
It acts as a backing metal at the butt joint with the first part, and is bent at a predetermined part, and the plate-like part at the end of the bend is attached and fixed to a member whose position is fixed. , second members 10, 12
It is a member that holds.

Next, the procedure for forming the above-mentioned welded joint will be explained.

First, the first member 10 and the second member 12 are prepared. Notches 1 are formed at regular intervals on the end surface of the second member 12.
6 is formed, and the second member 12 is butted against the first member 10 at the end face where this notch 16 is formed. Then, with the third member 14 in close contact with the back surfaces of these, the welding electrode rod is connected to the first,
From the surface side of the second members 10 and 12 (upper side in FIGS. 3 and 4), these joining lines (boundary line between both members)
A stick is moved along the line from one end to the other. At this time, welding conditions such as the moving speed of the welding rod and the welding current are the same for the region where the notch 16 is formed and the region where the notch 16 is not formed. As a result, the first and second members 10 and 12 are melted by the arc heat generated between these members and the electrode rod, and are melted together with the melted portion of the tip of the electrode rod or other filler material. Weld. At this time, the first
The third member on the back side of the second members 10 and 12 also has a first,
Arc heat is transferred via the second members 10 and 12. Whether or not the third member 14 is also melted by this heat depends on the plate thicknesses of the first and second members 10 and 12, welding conditions, etc.;
Conditions are set so that the member 14 melts in the vicinity of the joining line.

By the way, in the region where the notches 16 are provided at predetermined intervals along the joining line,
The first and second members 10 and 12 are melted by arc heat in the same manner as described above, and the third member 1
4 is heated directly by the arc heat in this part, so there is a large amount of melting, and therefore notch 1
The penetration depth is also deeper compared to the part without 6. Therefore, depending on the selection of welding conditions, the penetration depth of the third member 14 can be made to reach the back surface side only in the region where the notch 16 is located.
In other words, it is possible to cause the bead to appear on the back side and to generate extra welding, and under such welding conditions, each member can be joined with sufficient strength at any location.

That is, the third member 14 is melted and welded to the first and second members 10 and 12 over the entire thickness direction in the region where the notch 16 is present, and
Due to the existence of the gap formed by the notch 16, the first and second members 10 and 12 are welded uniformly and sufficiently at each end face over the entire thickness direction, and also due to the existence of the notch 16. Even in the parts that do not
If welding is carried out under the same conditions as those under which a bead appears on the back side of the part where the notch 16 is present, the melting has sufficiently progressed to the third member, so
This ensures that the third member is joined to the first and second members 10 and 12 with the required strength.

In this example, the case where the plate thickness is relatively thin and the welding work is completed by the first rod operation is explained as an example; however, if the plate thickness is even thicker, Even when the number of rods, that is, the number of passes is complicated, the above welding conditions can be set.

Now, the above-mentioned welding conditions are such that excess build-up is generated on the back side of the third member 14 in the part where the notch 16 is present, but excess build-up is not generated on the back side of the third member in the part where the notch 16 is not present. , it is possible to monitor and control not only insufficient heat input but also excessive heat input.
Compared to the conventional method of providing a certain gap between the members 10 and 12, it is easier to perform the welding work without causing burn-through, and therefore, the occurrence of perforation caused by this burn-through is avoided. effectively avoided. Furthermore, since the base material is not melted in excess of the desired amount, the consumption of welding power is greatly reduced, contributing to a reduction in processing costs. Moreover, the gap formed between the first and second members due to the presence of the notch 16 can be maintained accurately and precisely by simply bringing the first and second members 10, 12 into contact in the portion where the notch 16 is not present. Therefore, there is no need to take special measures to keep the gap constant as in the past.

Furthermore, by visually checking the bead appearing on the back side of the third member 14, it is possible to work while checking whether or not the welding conditions are properly maintained.
Alternatively, since it is possible to individually check for each joint whether or not the base materials have been sufficiently fused and welded, the defective rate can be reduced and quality control can be facilitated.

Furthermore, in this joint, the penetration depth in the third member 14 does not reach the back surface side at the part where the notch 16 is not formed during welding, so when welding the entire circumference of an annular member,
If a portion without such a notch 16 is selected for the lap portion between the start and end points of the electrode rod movement, the above-mentioned burn-through will not occur in this lap portion, and therefore, such melting will not occur, especially in the case of full-circumference welding. There is no need for a complicated and expensive device for switching welding conditions at the lap portion, which is required to prevent falling. Therefore, there are fewer failures of the welding equipment, which increases the equipment operating rate and contributes to reducing processing costs.

FIGS. 5 to 7 show experiments conducted to test the practicality of the joint of the above embodiment. Fifth
In the figure, an annular first member (plate thickness 2.0 mm) 1
8 and a second member 20 (plate thickness 1.5 mm) which is also annular and has a slightly thinner plate are abutted on each end surface, and a third member having an L-shaped cross section is abutted against each other at one end surface.
The member (plate thickness 1.5 mm) 22 is the first member, the second member 18,
20, and the welding procedure is the same as that described above. Note that the second member 20 has a trapezoidal notch 2 as shown in FIG. 6 before welding.
4 are provided at four locations at regular intervals.

FIG. 7 shows the penetration depth of the third member 22 in the joint formed as described above by welding a member without a notch using a pulse welding device or a welding device with switching control for switching the welding conditions. This is shown in comparison with the case where
The vertical axis in the figure shows the penetration depth (h in Fig. 5) in the third member 22, and A, B, C, and D indicate the penetration depth under each welding condition below, the width of the measured value and the average value (black circle ). Among these, A is when a pulse MIG welding device is used, B is when a MIG welding device with a switching control device is used, and C is a case where the dimensions at the notch 24 are 13 mm for a, 15 mm for b, and 1.0 mm for t in Fig. 6. In the case of mm, D indicates the case where the values of a and b are the same and the notch depth t is 1.5 mm. However, for C, only the penetration depth of the part where the notch 24 is located, and for D, the part where the notch 24 is located (indicated by D-B in the figure), and the part where it is not located (indicated by D-A in the figure).
The penetration depth of each is shown. Also, B
In order to prevent the burn-through mentioned above, welding conditions have to be weakened to some extent, so in order to ensure welding strength, welding is carried out around the entire circumference of the joint as a pre-process.
This shows the results when TFG welding is applied.

From FIG. 7, a notch 24 is provided in the second member 20,
Regarding the joint welded so that excess buildup is generated on the back side of the part where the notch 24 exists, the penetration depth (D-A in Fig. 7) is controlled by switching even in the part of the third member 22 where the notch 24 does not exist. It is understood that this value has reached the same level as the value B of the installation using a welding device with an attached welding device.

In addition, in D-RO in Fig. 7, the penetration depth
The part extending upward from the 1.5 mm line corresponds to the thickness of the extra layer formed on the back side, and from the value of C in the same figure, if the notch depth t is shallow, the extra layer will be thicker under the same welding conditions. It turns out that this does not occur. In other words, the shape, dimensions, etc. of the notch 24 should be selected appropriately in relation to the welding conditions, the thickness of the base material, the presence or absence of beveling, the shape of the bevel, the required welding quality, etc. be. Therefore, such a notch can have various shapes other than the shape described above. Figures 8 and 9 show specific examples.
In the figure, E indicates a rectangular shape with rounded corners, F indicates a substantially semi-elliptical shape, and G indicates a triangular shape. Further, FIG. 9 shows an example in which a rectangular notch 28 is provided in the second member 26 whose abutting ends are processed so that the groove shape is in a V-shape. In addition, in the figure, 30 is abutted against the second member 26, and the first member 32
is the backing money.

Furthermore, the number of such notches may be one depending on the case, and they may be provided on either side of a pair of members to be butt welded. Also, the backing metal placed on the back side of both these parts is omitted,
It is also possible to apply the present invention to a butt joint in which a pair of members are butt welded.

As described in detail above, the arc welding method according to the present invention involves forming at least one notch in one butt end face of two members to be butt welded, and welding them with or without a backing metal. Welding conditions in which two members are butted together, the part where there is a notch and the part where there is no notch are the same, and where the part where the notch exists, there is excess buildup on the back side, but where there is no notch, there is no extra buildup on the back side. This method is characterized by arc welding.

In this way, it is possible to confirm that the penetration depth is sufficient by showing the reinforcement on the back side in the part where the notch exists, while the reinforcement is visible on the back side in the part where the notch does not exist. By checking that the penetration depth is not excessive, it is possible to confirm that the penetration depth is not excessive, and thereby the welding conditions can be set within an appropriate range that is neither insufficient nor excessive.

Therefore, each joint base material is welded with sufficient penetration depth, and each joint can be easily and easily inspected, preventing burn-through and perforation during welding, and improving product quality. At the same time, wasteful power consumption is avoided.
Various excellent effects are produced, such as requiring only a simple welding device.

[Brief explanation of the drawing]

1 and 2 are a perspective view and a plan view, respectively, of a welded joint formed by the arc welding method of the present invention. FIG. 3 is a cross-sectional view of FIG. 2. FIG. 4 is a sectional view of FIG. 2.
FIG. 5 is a sectional view of a joint manufactured as a prototype to test the practicality of the arc welding method of the present invention. 6th
This figure is a plan view of the main part of the second member in FIG. 5 in a state before welding. FIG. 7 is a diagram showing the penetration depth of the third member in FIG. 5. FIGS. 8E to 8G and FIG. 9 are a plan view and a perspective view, respectively, showing other embodiments of the notch provided in the joining metal base material in carrying out the method of the present invention. 10, 18, 30: first member, 12, 20, 2
6: Second member, 14, 22: Third member, 16, 2
4, 28: Notch, 32: Backing metal.

Claims (1)

[Claims] 1. A method of butting and welding two members, in which at least one notch is formed in one butt end surface of the two members, the two members are butted together with or without a backing metal, and the notch is welded by butting the two members together. Perform arc welding under welding conditions that are the same in areas where there is and where there is not, and where excess build-up occurs on the back surface in areas where there is a notch, but no excess build-up occurs on the back surface in areas where there is no notch. An arc welding method characterized by: