End tab fixing method and end tab fixing jig

Abstract

To provide an end tab fixing method and an end tab fixing jig which stably fix and easily remove an end tab.SOLUTION: An abutting plate 11 is bridged between two welding objects (an upper column 1 and a lower column 2) as a plate member extending in a direction in which the welding objects are opposed, one side of an end tab 6 in a welding direction is abutted on one surface of the abutting plate 11, and the end tab 6 is gripped or the like using a gripping member (a middle clamp 14) from the other surface of the abutting plate 11 and a surface of the end tab 6 on an opposite side to the abutting plate 11, in order to attach the end tab 6 to the abutting plate 11 so that the end tab 6 is positioned between the welding objects.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and a fixture for fixing an end tab that is placed at a weld joint when welding a steel column using a welding robot. [Background technology]

[0002] Conventionally, when robotically welding steel columns such as square steel pipes, a ceramic stopper (end tab) is fixed to the weld joint to prevent the hot weld metal from flowing outside the weld joint. The end tabs must be securely fixed in place so that they do not move during the welding process, but must also be easily removable after welding. For this reason, magnetic clamps are often used to secure the end tabs (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-294797 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional magnetic clamps have problems such as insufficient spring force, which can cause the end tab to shift position due to contact with the welding nozzle or the arc, resulting in poor welding quality.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a method for fixing an end tab that stably fixes the end tab and allows for easy removal, and a jig used for fixing the end tab. [Means for solving the problem]

[0006] The present invention is a method for fixing an end tab to a welded joint between two workpieces held facing each other, characterized in that a plate member extending in the direction in which the workpieces face each other is placed between the two workpieces, and the end tab is fixed to the plate member so that it is positioned between the two workpieces. This allows the end tab to be stably fixed to the welded joint portion. Furthermore, one surface of the end tab in the welding direction is abutted against one surface of the plate member, and the other surface of the plate member and the surface of the end tab opposite the plate member are gripped with a gripping member, thereby fixing the end tab between the two workpieces. This allows the end tab to be stably fixed, and can be easily removed after welding.

[0007] The present invention also provides an end tab fixing jig that fixes an end tab to a welded joint between two workpieces held facing each other, comprising: a plate member that is bridged between the two workpieces and extends in the direction in which the workpieces face each other, with one surface abutting against one surface of the end tab; and fixing means that fixes the end tab to the plate member so that the end tab is positioned between the two workpieces. This allows the end tab to be stably fixed to the welded joint portion. Furthermore, the fixing means is a gripping means having one surface abutting against the other surface of the end tab and the other surface abutting against the other surface of the plate member, thereby gripping and fixing the end tab from both sides in the welding direction, so that the end tab can be stably fixed without shifting. Furthermore, since the end tab is gripped by the gripping member, it can be easily removed. Furthermore, a protrusion that protrudes between the two workpieces is provided at the position of the plate member where it abuts against the end tab, thereby increasing the contact area between the plate member and the end tab, thereby enabling the end tab to be securely gripped. Furthermore, if the shape of at least the portion of the protrusion that is inserted between the workpieces, as viewed in the thickness direction of the plate member, is made similar to the shape of the welded joint as viewed in the thickness direction of the plate member, the contact area between the plate member and the end tab at the welded joint can be increased, and the end tab can be gripped more stably. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are a front view and a plan view showing an embodiment of the present invention. [Figure 2] 1 is a perspective view showing an embodiment of the present invention. [Figure 3] 10A to 10C are diagrams showing a method for fixing an end tab according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1(a), (b), and 2 show this embodiment, with 1(a) being a front view, 1(b) being a plan view, and 2 being a perspective view of the main parts. In each figure, 1 is an upper column, 2 is a lower column, 3 is a backing metal, 4 is an erection piece, 5 is an erection adjustment jig, 6 is an end tab, and 10 is an end tab fixing jig according to the present invention. The end tab fixing jig 10 includes a contact plate 11, an upper clamp 12, a lower clamp 13, and a middle clamp 14. In order to make it easier to understand how the end tab 6 is held, the upper clamp 12 and the lower clamp 13 are omitted from Figure 1(b). In this example, an end tab 6 is fixed to the weld joint using an end tab fixing jig 10, and two workpieces, an upper column 1 and a lower column 2, which are held facing each other in the vertical direction, which is the vertical direction in Figure 1(a), are welded by a welding robot.

[0010] The upper column 1 is a rectangular steel pipe with a square cross section, and at its lower end is formed a sloped portion 1n whose thickness becomes thinner as it goes downward. On the other hand, the lower column 2 is a rectangular steel pipe with the same cross section as the upper column 1, and its thickness is constant in the vertical direction. As will be described later, the upper column 1 and the lower column 2 are temporarily fixed so that they face each other with a predetermined distance between them. In this example, the lower column 2 is fixed to a foundation (not shown) or a steel frame placed on the foundation, and before temporary fixing, the upper column 1 is suspended above the lower column 2 by a rope or the like. The backing metal 3 is provided on the inside of the upper column 1 so that its outer periphery abuts against the upper column 1, and is a rectangular steel pipe with a square cross section that extends from the upper side of the sloped portion 1n of the upper column 1 to the inside of the lower column 2, with its upper end attached by welding to the upper column 1. The backing metal 3 may also be attached to the inside of the lower column 2. The erection piece 4 is a plate member that protrudes from the center of each outer peripheral surface of the upper column 1 and the lower column 2 in a direction perpendicular to the outer peripheral surface and extends in the vertical direction, and the erection piece provided on the upper column 1 (hereinafter referred to as the upper erection piece 4A) is welded to the upper column 1 so that its lower end is positioned above the sloped portion 1n, and the erection piece provided on the lower column 2 (hereinafter referred to as the lower erection piece 4B) is welded to the lower column 2 so that its upper end is positioned below the upper surface 2n of the lower column 2. A fall prevention bar 4n, which is a rod-shaped member that protrudes upward from the upper end, is provided at the upper end of the upper erection piece 4A on the side opposite to the upper column 1. Note that the fall prevention bar 4n is not an essential element, so it does not have to be provided.

[0011] The erection adjustment jig 5 includes a frame 51, a tilt adjustment means 52, misalignment adjustment bolts 53 and 54, a fall prevention bolt 55, and fixing bolts 56 and 57, and temporarily fixes the upper column 1 and the lower column 2 by connecting the upper erection piece 4A and the lower erection piece 4B. The frame 51 is a vertically elongated annular member having two vertical plates 51a, 51b arranged at a predetermined distance from each other and having plate surfaces parallel to the plate surfaces of the upper and lower erection pieces 4A, 4B, and upper and lower horizontal plates 51c, 51d that connect the two vertical plates 51a, 51b at their upper and lower ends, respectively, and has an upper part that receives the upper erection piece 4A and a lower part that receives the lower erection piece 4B. In the upper part, the distance between the two vertical plates 51a and 51b is approximately equal to the thickness dimension of the upper erection piece 4A. On the other hand, in the lower part, in order to adjust the positional deviation (misalignment adjustment) between the upper column 1 and the lower column 2 described later, the distance between the two vertical plates 51a and 51b is made larger than the thickness dimension of the upper erection piece 4A. The erection adjustment jig 5 is placed on the upper end of the upper erection piece 4A by placing the inside of the upper horizontal plate 51c of the frame 51 on the upper end of the upper erection piece 4A, and attaching it to the upper and lower erection pieces 4A, 4B with each bolt 53 to 57 while the surface of the upper horizontal plate 51c opposite the upper column 1 is abutted against the fall prevention bar 4n, thereby temporarily fixing the upper column 1 and the lower column 2. Note that in FIG. 1(a), the screw holes for screwing in the bolts 53 to 57 are omitted.

[0012] The tilt adjustment means 52 includes a shim plate 52a, a cam arm 52b arranged on the shim plate 52a, a seat plate 52c arranged on the cam arm 52b, and a tilt adjustment bolt 58. The shim plate 52a is a plate-shaped member arranged above the lower erection piece 4B and having a sloped portion on the lower erection piece 4B side that becomes thinner as it gets closer to the lower erection piece 4B. After the cam arm 52b and seat plate 52c are arranged between the upper erection piece 4A and the lower erection piece 4B, the shim plate 52a is inserted between the cam arm 52b and the lower erection piece 4B. The cam arm 52b is a member whose shape is an inverted L when viewed from the thickness direction of the upper and lower erection pieces 4A, 4B, and has one end 52b1 that contacts the seat plate 52c on the pillar side (here, the upper pillar 1 side), the other end 52b2 which is the end opposite the pillar side, and a starting point 52b3 that is located between the one end 52b1 and the other end 52b2 and is convex downward. The starting point 52b3 contacts the shim plate 52a. A screw hole 59 for screwing in the tilt adjustment bolt 58 is formed in the seat plate 52c. The screw hole 59 penetrates the seat plate 52c in the vertical direction. Therefore, when the tilt adjustment bolt 58 is rotated and moved downward, a downward force acts on the other end 52b2 of the cam arm 52b, so that one end 52b1 of the cam arm 52b moves upward, and as a result, a force acts obliquely upward on the upper erection piece 4A via the seat plate 52c, so that the angle (degree of tilt) of the axis of the upper column 1 relative to the axis of the lower column 2 can be changed. That is, the tilt adjustment means 52 adjusts the screw-in depth of the tilt adjustment bolt 58 to adjust the magnitude of the tilt (tilt adjustment).

[0013] The misalignment adjustment bolts 53, 54 are attached to the lower erection piece 4B side of the two vertical plates 51a, 51b of the frame 51 so as to face each other in the thickness direction, and adjust the positional deviation of the upper column 1 in the width direction relative to the lower column 2 (in the central frame 51 in FIG. 1(a), the positional deviation in the left and right direction in the same figure). Taking the above central frame 51 as an example, if the upper column 1 is misaligned to the right relative to the lower column 2, the misalignment adjustment bolt 53 attached to the right vertical plate 51a is pressed against the lower erection piece 4B to move the upper column 1 to the left and correct the misalignment between the upper column 1 and the lower column 2. Conversely, if the upper column 1 is misaligned to the left, the misalignment adjustment bolt 54 attached to the left vertical plate 51b is pressed against the lower erection piece 4B to correct the misalignment by moving the upper column 1 to the right. The fall prevention bolt 55 is screwed into a screw hole (not shown) provided in the lower horizontal plate 51d of the frame 51 and extending in the vertical direction, and is pressed against the lower erection piece 4B from below. That is, the fall prevention bolt 55 fixes the erection adjustment jig 5 to the lower erection piece 4B from below, thereby preventing the upper column 1 from falling and adjusting the vertical height of the upper column 1 relative to the lower column 2. The fixing bolts 56 and 57 are provided on the side surface opposite to the upper erection piece 4A side of one vertical plate (here, the vertical plate 51a) of the frame 51, and are screwed into screw holes (not shown) extending in the thickness direction of the vertical plate 51a, and are pressed against the upper erection piece 4A from the thickness direction of the upper erection piece 4A. In other words, the fixing bolts 56 and 57 have the function of fixing the erection adjustment jig 5 to the lower erection piece 4B from its thickness direction.

[0014] When temporarily fixing the upper erection piece 4A and the lower erection piece 4B using the erection adjustment jig 5, first, misalignment adjustment is performed using the misalignment adjustment bolts 53 and 54, level adjustment is performed using the fall prevention bolt 55, and tilt adjustment is performed using the tilt adjustment bolt 58. Then, the upper column 1 and the lower column 2 are temporarily fixed using the fixing bolts 56 and 57. As a result of this temporary fixation, as shown in Figure 2, a groove 7 is formed around the entire circumference between the upper column 1 and the lower column 2, surrounded by the sloped portion 1n of the upper column 1, the upper surface 2n of the lower column 2, and the backing metal 3, and whose cross-sectional shape when viewed from the circumferential direction of the upper column 1 or the lower column 2 (hereinafter referred to as the column circumferential direction). The groove 7 has a right-angled trapezoidal shape. Hereinafter, when there is no need to distinguish between the upper erection piece 4A and the lower erection piece 4B, the upper erection piece 4A and the lower erection piece 4B will be referred to as the erection piece 4.

[0015] The end tab 6 is a plate-shaped member with a plate surface perpendicular to the column circumferential direction, which is the thickness direction of the erection piece 4, and is made by adding a binder to a metal oxide containing silicon dioxide and molding (sintering). The end tab 6 is placed in the groove 7 formed between the upper column 1 and the lower column 2, which is the welded joint between the objects to be welded, so that the plate surface is perpendicular to the welding direction. As shown in Figure 2, in this example, the shape of the plate surface of the end tab 6 on the contact plate 11 side and the shape of the plate surface on the opposite side from the contact plate 11 are both rectangular, with the tip side (the side inserted into the groove 7) having the same shape as the groove 7. The end tabs 6 are arranged as follows: In FIG. 1(b), the left side of the drawing is the right side, the right side is the left side, the lower side is the front side, and the upper side is the rear side, and the front erection piece is the front piece 41, the left erection piece is the left piece 42, the rear erection piece is the rear piece 43, and the right erection piece is the right piece 44. Pieces 41 to 44 refer to the erection pieces 4 of the upper column 1 and the lower column 2. In this example, the upper column 1 and the lower column 2 are welded together in two steps. In the first step, the area between piece 41 and piece 42, indicated by R11 in the figure, and the area between piece 43 and piece 44, indicated by R12 in the figure, are welded. In the second step, the area between piece 42 and piece 43, indicated by R21 in the figure, and the area between piece 41 and piece 44, indicated by R22 in the figure, are welded. At the time of the second welding, the upper column 1 and the lower column 2 are connected by the first welding, so the second welding is performed after recovering the end tab 6, removing the erection adjustment jig 5, and melting and removing the erection piece 4. As such, the end tabs 6 are used only during the first welding, and are therefore placed at both ends of the areas R11 and R12 where the first welding is performed (the left side of the front piece 41, the front side of the left piece 42, the right side of the rear piece 43, and the rear side of the right piece 44), and are withdrawn after the first welding.

[0016] The end tab fixing jig 10 is a jig for gripping the end tab 6 from both sides in the circumferential direction of the upper pillar 1 and the lower pillar 2 to be welded, which is the extension direction of the groove 7, and fixing it to the weld joint, and as described above, is equipped with the abutment plate 11, the upper clamp 12, the lower clamp 13, and the middle clamp 14. The abutment plate 11 has a long plate body 11a that is hung between the upper column 1 and the lower column 2 and extends in the vertical direction, and a protruding portion 11b that protrudes in the width direction of the plate body 11a from approximately the center of the plate body 11a, and is fixed to the erection piece 4 with one plate surface abutting against the erection piece 4 and the tip side of the protruding portion 11 facing the groove 7 direction. The abutment plate 11 is fixed at its upper end to the erection piece 4 on the upper column 1 side by an upper clamp 12, and at its lower end to the erection piece 4 on the lower column 2 side by a lower clamp 13. In this example, well-known C-clamps are used as the upper clamp 12 to the middle clamp 14. Taking the middle clamp 14 as an example, as shown in the upper right diagram of Figure 2, a C-clamp has a U-shaped clamp body 14a, a screw 14b, and a handle 14c. By turning the handle 14c and moving the screw threaded into one of the opposing sides of the U-shape (screw side piece 14p) to the other opposing side of the U-shape (contact piece 14q), the spacing of opening 14s, which is the space between the end of contact piece 14q, which is the tip of screw 14b, and contact piece 14q, is narrowed, and the object can be firmly gripped by the jig that grips the object at opening 14s, and the object can be easily removed by rotating screw 14b in the opposite direction to widen the spacing of the opening.

[0017] Next, a method for fixing the end tab 6 will be described. First, an end tab fixing jig 10 including a contact plate 11, an upper clamp 12, a lower clamp 13, and a middle clamp 14 as shown in FIG. 3(a) is prepared. Next, as shown in FIG. 3(b), the plate surface of the plate body 11a of the abutment plate 11 is brought into close contact with the erection piece 4 of the upper column 1 and the erection piece 4 of the lower column 2, and the lower end of the protruding portion 11b of the abutment plate 11 is placed on the upper surface of the lower column 2 of the groove 7. The upper end of the plate body 11a is attached to the erection piece 4 of the upper column 1 using the upper clamp 12, and the lower end is attached to the erection piece 4 of the lower column 2 using the lower clamp 13. Next, as shown in Figure 3(c), the end tab 6 is placed in the groove 7 with one of its plate surfaces abutting against the abutment plate 11, and then the end tab 6 is fixed in place by the middle clamp 14. Specifically, as shown in Figure 2, the side of the end tab 6 opposite the abutment plate 11 is abutted against the abutment piece 14q of the main body 14a of the middle clamp 14, and the plate surface of the abutment plate 11 opposite the end tab 6 is abutted against the screw 14b, and the screw 14b is tightened to fix the end tab 6 in abutment against the abutment plate 11. This allows the end tab 6 to be firmly and stably fixed to the welded joint. Furthermore, when removing the end tab 6, the screw 14b of the middle clamp 14 is loosened and the middle clamp 14 is removed, so that the end tab 6 can be easily removed. After the first welding, the end tab 6 and the end tab fixing jig 10 are removed, the erection adjustment jig 5 is removed, the erection piece 4 is melted, and then the second welding is performed.

[0018] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0019] For example, in the above embodiment, the end tabs 6 are fixed to the abutment plate 11 using the middle clamps 14, which are gripping members, but they may also be fixed to the abutment plate 11 using double-sided tape. Also, the end tabs 6 may be fixed to the abutment plate 11 using other fixing means, such as using an adhesive. Alternatively, the end tab 6 may be fixed to the abutment plate 11 by forming a pin hole of a predetermined depth in the end tab 6 and a through hole in the abutment plate 11, and joining the end tab 6 and the abutment plate 11 with a pin. It is preferable to use two or more pins. In addition, in the above embodiment, the abutment plate 11 was attached to the erection piece 4 of the upper column 1 and the erection piece 4 of the lower column 2 using the upper clamp 12 and the lower clamp 13, but bolts and nuts may be used instead of clamps. In addition, in the above embodiment, the upper column 1 and the lower column 2 are made of square steel pipes, but they may also be made of other steel columns such as round steel pipes or box columns. In addition, in the above embodiment, the abutment plate 11 is attached to the erection piece 4, but if there is no erection piece 4 on the upper column 1 or the lower column 2, the abutment plate 11 can be attached directly to the upper column 1 and the lower column 2 using a magnet or a magnetic clamp, etc. [Explanation of symbols]

[0020] 1 upper column, 1n slope, 2 lower column, 2n upper surface of lower column, 3 backing metal, 4, 4A, 4B Erection piece, 4n Fall prevention bar, 5 Erection adjustment jig, 6 end tab, 7 groove, 10 end tab fixing jig, 11 abutment plate, 11a plate body, 11b protrusion, 12 upper clamp, 13 lower clamp, 14 Medium clamp.

Claims

1. 1. A method for securing an end tab to a weld joint between two workpieces held opposite each other, comprising: a plate member extending in a direction in which the workpieces face each other is placed between the two workpieces, and the end tab is fixed to the plate member so that the end tab is positioned between the two workpieces.

2. 2. The method for fixing an end tab according to claim 1, wherein one surface of the end tab in the welding direction is brought into contact with one surface of the plate member, and the other surface of the plate member and a surface of the end tab opposite the plate member are gripped with a gripping member, thereby fixing the end tab between the two workpieces to be welded.

3. An end tab fixing jig for fixing an end tab to a welded joint between two workpieces held facing each other, a plate member that is bridged between the two workpieces and extends in a direction in which the workpieces face each other, one surface of which abuts against one surface of the end tab; and a fixing means for fixing the end tab to the plate member so that the end tab is positioned between the two workpieces.

4. the fastening means comprises a gripping member for gripping the end tab; The gripping member is 4. The end tab fixing jig according to claim 3, wherein one surface abuts against the other surface of the end tab and the other surface abuts against the other surface of the plate member, thereby gripping and fixing the end tab from both sides in the welding direction.

5. 5. The end tab fixing jig according to claim 4, wherein a protrusion is provided on the plate member at a position where the plate member abuts against the end tab, the protrusion protruding between the two workpieces.

6. 6. The end tab fixing jig according to claim 5, wherein the shape of at least the portion of the protrusion that is inserted between the workpieces, as viewed in the thickness direction of the plate members, is similar to the shape of the welded joint as viewed in the thickness direction of the plate members.

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