JPH02307677A - Automatic welding method for polygonal member - Google Patents

Abstract

PURPOSE:To set the bead height of a circular arc part to the same height as that of a linear part by allowing a polygonal member to be rotated with a positioner, and setting the welding speed at the time of welding the circular arc part with a welding robot to the specific speed. CONSTITUTION:A linear part 11a is welded at the welding speed VS, and from the start point B of a corner part 12a to an end point C, welding is executed by changing the speed to the welding speed VC shown by the expression. Where, (h) ri, and VfS, VfC in the expression denote the height of a welding bead, the inside peripheral radius of the welding bead of the i-th layer of a circular arc part, and the feeding speeds of an eldctrode wire at the time of welding the linear part and the circular arc part, respectively. While executing the welding, a joint core 30 is rotated by a 90 deg. positioner, and a welding torch 1 is moved by synchronizing it therewith. When the welding of the corner part 12a is ended, and the welding torch reaches the end point C, the welding speed is switched from VC to VS and the whole periphery is welded similarly. In such a manner, the bead height of the circular arc part can be set to the same height as that of the linear part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic welding method for rectangular members such as shikichi cores used for joints between columns and beams.

[Prior Art] Shiguchi cores in steel frame structures are used at joints between steel columns and steel beams such as H-beams, as shown in Figures 8 and 9. , 30 is a shikichi core, 34
36 is a steel column and 36 is a steel beam.

Such a shikichi core 30 is generally welded to a rectangular square column 31 and both upper and lower ends of this column 31, and is attached to a beam 36.
diaphragm 32 for transmitting stress from the diaphragm 32. The joint between the column 31 and the diaphragm 32 is usually a butt joint, and the shape of the groove 33 is 10th.
As shown in the figure, it is a rectangular shape or normal. Bevel like this 3
In step 3, multi-layer welding is performed to manufacture the shiiguchi core 30. In addition, in FIG. 10, 38 is a backing.

Then, a pillar 34 is attached to the surface of the diaphragm 32 of the shikichi core 30.
The steel shelving structure is constructed by welding the end faces of the beam 36 to the side of the diaphragm 32 and the surface of the column 31.

Although the above-mentioned Shiguchi core 30 has a relatively simple shape,
The weld line between the rectangular column 31 and the diaphragm 32 is a combination of a straight part corresponding to the side of the column 31 and a circular arc part corresponding to a part of the corner. Therefore, it is particularly difficult to weld a part of the corner, so conventionally, the straight part and part of the corner were separately welded by semi-automatic welding. However, welding the straight part and the corner part separately is not only inefficient, but also increases the number of weld bead joints, which may cause welding defects or cause defects in the bead shape. There was a problem. Therefore, automation of welding is required. For this reason, it may be possible to use a welding robot, etc., but even in such automatic welding, it is not only necessary to change the welding conditions (welding speed, current, etc.) for straight sections and some corners, but also for multi-layer welding. There is a problem in that it takes a lot of time and effort to create a welding program because it is a welding process. Furthermore, the accuracy of the column 31 is not always good, which makes it even more difficult to automate welding.

[Problem to be solved by the invention] The biggest problem with automatic welding in the shikichi core 30 is:
It is clear that part of the corner of column 31 is welded. One of these is optimizing the welding speed at some corners and smoothing the bead shape. In other words, when a weld line including a straight part and a circular arc part is placed in a vertical plane, if the welding speed at a part of the corner is inappropriate, not only will it not be possible to obtain the same bead height as the straight part, but even if the welding speed is Even if the center of gravity of the molten pool is located far back from the arc point, upward welding will occur in some corners, which tends to cause the cross-sectional shape of the bead to be convex, and the bead height may vary. The bead shape may become distorted and the smoothness of the bead shape may be impaired. Therefore, as a countermeasure to this problem, it is necessary to make the molten pool as small as possible, that is, to make the molten pool's center of gravity closer to the arc point.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an automatic welding method for automatically welding a rectangular member such as a joint core, which optimizes the welding speed particularly at a corner part and smoothes the bead shape.

[Means for Solving the Problems] In order to achieve the above object, the automatic welding method for a square member according to the present invention provides a method for automatically welding a square member in which a welding line is placed in a vertical plane and includes a straight portion and a circular arc portion. In automatic welding, a welding robot and a positioner including a means for attaching a square member and rotating it by a predetermined angle are used to weld a groove, and in this case, the welding current value in the circular arc part is changed from that in the straight part. If welding is performed at a lower speed, and the welding speeds in the straight section and the arc section are v and v, respectively, and the feeding speeds of the electrode wire S are v and ■, respectively, the arc fs
The arcuate portion is welded by rotating the rectangular member in synchronization with the operation of the welding robot so that the welding speed V at the fc portion satisfies the following equation.

Here, h is the height of the weld bead, and r is the inner radius of the weld bead of the first layer of the arc portion.

[Operation] A welding robot welds a groove to a square member attached to a positioner. In this case, the weld line is placed in a vertical plane and includes a straight section and a circular arc section. Then, for the straight part, welding current value, wire feeding speed Vf
Weld at s and welding speed v8, and apply the above ■ to the arc part.
Lower welding current value ■, similarly slower wire feeding speed ■ than v, 8 above. and Welding speed V corrected by taking into account the change in wire feeding speed due to the reduction in welding current value for (8) above, specifically, welding speed /iv that satisfies the above formula (]) Weld. That is, if the welding current value is lower in the arc portion than in the straight portion, the molten pool becomes smaller and its center of gravity approaches the arc point, so that the upward welding condition can be quickly eliminated. However, if the welding current value is lowered, the wire feed speed will naturally become slower in the arc section, so in order to keep the bead height the same, it is necessary to correct the welding speed by taking into account the change in wire feed speed. There is. The bead height does not change even in this bundling and arcuate portion, and the smoothness of the bead shape can be maintained.

- By the way, when welding arc parts, the positioner operates in synchronization with the welding robot. Therefore, when the welding torch reaches the starting point of the circular arc part from the straight part, the square member is rotated by a predetermined angle by the positioner, the welding current value is simultaneously lowered, and the welding speed is relatively switched from the above-mentioned V to V.

S C Next, when the welding torch reaches the end point of its circular arc portion (during this time, the rotation of the square member has finished), at the same time the welding current value is increased and the welding speed is switched from the above ■ to V. Weld the next straight section at this speed S. Thereafter, by repeating the same operation, the square member can be continuously and automatically welded all around.

[Example code] Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(c) are explanatory views of the operation when automatically welding the welding line of the joint core continuously all around the circumference.

In this case, the weld line 10 is placed in a vertical plane, and the straight section 11
a, 1], b, ], 1c, lld and corner part 12 a
, 12 b, 12 c, and 12 d. The welding torch 1 is perpendicular to this welding line 10 and inclined at a certain angle backward or forward (in the direction of the front and back of the page), and at the above-mentioned part of the corner, its axis is directed toward the center of curvature of the part of the corner. The posture is controlled as follows. In addition,
The cross-sectional shape of the groove is uniform around the entire circumference.

In FIG. 1, the outline shape of the cross section of the joint core 30 is shown by a broken line, and the joint core 30 is placed in a positioner τj as will be described later, and is controlled to operate in synchronization with the welding robot. be done.

The welding operation will be explained based on FIG. First, a welding starting point A is set at an appropriate position on the horizontal straight section 11a (see FIG. 1(a)). This starting point A and connection points B and C between each straight section and a corner part.

The positions of D, . Further, the welding current value is changed and set corresponding to these straight portions and a portion of the corner. In other words, in some corners, a value I (usually S
C10-30% reduction). Furthermore, the feeding speed of the electrode wire 2 varies from Vfs in the straight section to ■ in the corner part. At the same time, as the welding current value decreases, the wire feeding speed also slows down, so the welding speed V at some corners is corrected by taking into account the change in the wire feeding speed according to equation (1) above. controlled like this. Therefore, from the welding start point A to the first corner part 12
Welding is performed at the previously set welding speed V up to the starting point B of point a. The welding current value at this time is I, and the wire feeding speed is vfs.

Next, from the starting point B to the ending point C of the first corner portion 12a, welding is performed by changing the welding speed V 2 to a welding speed V 2 that satisfies the above equation (1) (see FIG. 1(b)). The welding current value I at this time is lower than the welding current value I in the straight section, and accordingly, the wire feeding speed V. The wire feeding speed vfs is also slower than the wire feeding speed vfs in the straight section. Therefore, in order to obtain the same height as the straight part even in some corners,
Welding speed V. Therefore, it is necessary to make a correction that takes into account changes in the wire feeding speed. In addition, in the case of welding a part of the corner, as will be described later, the Shiguchi core 30 is welded at the same time.
Weld while rotating by 0°.

Next, the determination of the welding speed V 2 of the above-mentioned corner part will be explained with reference to FIG. 2. First, it is assumed that the cross-sectional shape of the groove is uniform in both the straight portion and the corner portion.

The amount of welding W when a part of the corner of the inner curvature radius r is moved at the welding speed V to obtain the bead height h in the straight section, and
The welding speed V to obtain the same bead height h at the corner part and the welding amount W when moving a part of the coat with the radius of curvature r are expressed as follows.

In addition, when moving a part of the corner with the radius of curvature r at a speed of 1 wire feeding speed V, welding amount Wit, C
S x -'' knee W8 vo vrS Therefore, the above equation (1) can be obtained.

Now, if the wire feeding speed is the same for both the straight part and the corner part, and only the welding speed is changed, the welding speed V of the corner part will be O. Therefore, if the wire feed rate is constant, (
By controlling the welding speed of a part of the corner according to equation 2), the bead height h of the part of the corner can be made the same as that of the straight part. However, the welding of a part of the corner is generally upward welding. This will be explained with reference to FIGS. 3 and 4.

In arc welding, the arc point 3 and the center of gravity G of the molten pool 4 do not coincide as shown in FIG. 3, and there is some heat toward the rear. This distance Ω is mainly related to the welding current value, and is about ρ-5 to 6+nm when the welding current value 1=250A.

Therefore, if the shikichi core 30 starts rotating when the arc point 3 reaches the R end of a part of a certain corner (the connection point between the straight part and the part of the corner), as shown in FIG. 4(a), , the tangent line 5 at the center of gravity G of the melt pool 4 is not horizontal, and there is an inclination angle α('', Q /r
,)have.

Further, the inclination angle α at a part of the corner is illustrated as shown in FIG. 4(b). In the figure, ■ is the welding speed of the adjacent straight section.

In this way, the center of gravity of the molten pool 4 is always exposed to an upward slope in a part of the corner, which results in a state similar to upward welding, and the cross-sectional shape of the bead 7 becomes convex as shown in FIG. 5(a). Moreover, the bead height 1] may be distorted to the same height as the straight portion, as shown in FIG.

Therefore, by lowering the welding current value in a part of the corner, the molten pool 4 is made as small as possible, thereby bringing the center of gravity G of the molten pool 4 closer to the arc point 3. Further, by doing so, the inclination angle α becomes close to zero and becomes close to horizontal, so that the upward welding state can be almost eliminated. As a result, the above-mentioned defects in bead shape do not occur, and the bead becomes smooth.

Of course, the bead height does not change.

Therefore, in the present invention, the welding current value is lowered in a part of the corner, and the welding speed V is set according to the above formula (1), taking into account the change in wire feeding speed caused by this.

Returning to FIG. 1 again, the rotation of the joint core 30 will be explained. When the welding core 30 reaches the point B, the positioner rotates it 90 degrees around the 0 point. at the same time,
Welding 1.--chi.1 is moved in synchronization with this rotational movement (see FIG. 1(b)). It goes without saying that the welding current value and wire feeding speed are also changed to values I and C V, which are smaller than those for the straight section, respectively, as described above.

Also, during the rotation operation of the joint core 30, the first corner portion 12a
The welding speed V is controlled so as to satisfy the above equation (1). By the way, the motion trajectory of point B B-B-81 (15)
is known, the locus of motion of 1. The rotation speed (known) can be controlled so as to relatively satisfy the above equation (1).

To explain the means for realizing the welding speed V at the arc portion of any one corner, in Fig. 6, Ll: Length of the vertical side of the weld line L2: Length of the horizontal side of the weld line R: Curvature of the arc portion If the rotation radius of the center is r and the radius of the arc part, then the length of the arc part of one corner = πr / 2 The distance the robot moves when welding that arc part - πR / 2 When L1 = L2, R = ,,/-d (L/2-r), therefore, the robot movement speed V to realize the welding speed V. (Rob) is as follows. Therefore, when the torch reaches a part of the corner, the positioner starts rotating, and the robot only needs to move on an arc of radius R at a speed R/rX v .

Note that the rotational speed of the positioner is /IQt since the torch only needs to rotate by 90 degrees during (1) while moving on the arc of a part of one corner, and the rotational angular speed of the positioner is as follows.

When the welding torch 1 reaches the end point C of 2a], the welding speed is switched from the above V to V8, and the welding current value and wire feeding speed are also changed from the above 1 to the higher I. , vfcS to faster vfS, and weld the next second straight section], 1b at this welding speed v8 (see Fig. 1 (C)). Thereafter, in the same manner as above, the second corner part 12b and the third corner part 12b
Straight section 11C1 3rd corner part 12C1 4th straight section] 1
d, and the fourth corner portion 12d, and then return to the welding start point A of the first straight portion 11a and go around. From the second layer onwards, the two-legged action will be repeated. In this way, the joint core 30 can be continuously and automatically welded all around.

Next, FIG. 7 is a perspective view of a welding device that performs the above-mentioned automatic welding. It is composed of.

The positioner 24 has a rotary table 25 on which the shikichi core 30 is horizontally cantilevered.
5, the joint core 30 is rotated by a predetermined angle. This operation is performed in synchronization with the operation of the welding hole I/20 as described above.

As is clear from the above description, the welding line]0 is not limited to a square shape, but can be similarly applied to a polygonal shape, such as a triangle, pentagon, or hexagon.

[Effects of the Invention] As described above, according to the present invention, a welding robot and a positioner are used to continuously weld the entire circumference of a rectangular part where the weld line is placed in a vertical plane and includes a straight part and a circular arc part. Automatic welding is possible, the welding current value in the circular arc section is lower than that in the straight section, and the welding speed V is lower than the welding speed V in the straight section.
Since we decided to weld the circular arc part by switching the switch so that formula (1) above is satisfied, the molten pool in the circular arc part becomes smaller and its center of gravity approaches the arc point, so upward welding is performed. As a result, the bead height can be the same as that of the straight portion, and the bead shape can be made smooth.

[Brief explanation of drawings]

Figures 1 (a) to (c) are explanatory diagrams of the operation of the automatic welding method for square parts according to the present invention, Figure 2 is an explanatory diagram for determining the welding speed of a part of a corner (arc part), and Figure 3 The figure shows the relationship between the distance ρ between the arc point and the center of gravity of the molten pool, and Figure 4 (a
) and (b) are diagrams published by Kakugaibu that show the state in which the tangent at the center of gravity of the melt pool during rotation shows an inclination angle and the state in which the inclination angle changes. A diagram showing the bead shape of a part of the corner when the pool is large, Figure 6 is a diagram used as a means to realize the welding speed V at a circular arc part, and Figure 7 is a diagram of the welding device used in the automatic welding method of the present invention. FIG. 8 is a perspective view showing the state of use of the Shiguchi core, FIG. 9 is a perspective view of the Shiguchi core, and FIG. 10 is a sectional view of the groove in the Shiguchi core. 1... Welding torch 2... Electrode wire 3, Arc point 4... Molten pool 10... Welding line 11a-lld... Straight section 12a-12d, Corner part (circular arc section) 20... Welding robot 24・bojinyona 25・rotary table 30・shiguchi core 33・bevel

Claims (1)

[Claims] Automatic welding of a rectangular member in which the welding line is placed in a vertical plane and includes a straight portion and a circular arc portion, the method comprising: a welding robot; and means for attaching the rectangular member and rotating it by a predetermined angle. The groove is welded using a positioner, and in this case, the welding current value is lower in the arc part of the weld line than in the straight part, and the welding speed in the straight part and the arc part is set to v_s, respectively. v_c, and the electrode wire feeding speeds are V_f_s and V_f_s, respectively.
When _f_c, welding speed v_c at the arc portion
A method for automatically welding a square member, characterized in that the square member is rotated in synchronization with the operation of the welding robot so that the following formula is satisfied, and the circular arc portion is welded. v_c=v_s×(2r_i/2r_i+h)×(v_
f_c/v_f_s) However, h: Height of the weld bead r_i: Inner circumferential radius of the weld bead of the i-th layer of the arc portion