Method for fastening a welding rod and welding device with a welding rod fastened vertically by the method

Abstract

A method for fastening a welding rod that can fix a welding rod perpendicular to a welding surface and reduce a spatter phenomenon in which metal particles scatter around a welded part due to an inconsistent welding angle during welding, and a welding device in which a welding rod is fastened perpendicularly by the method are disclosed. The method for fastening a welding rod is a method for fastening a welding rod to a welding rod fixing block having a welding rod accommodating hole formed therein, and includes the steps of (a) inserting the welding rod into the welding rod accommodating hole of the welding rod fixing block, and (b) fastening fixing screws into both sides of the welding rod accommodating hole to tighten the welding rod accommodating hole based on the welding rod, and is characterized in that the fixing screws fastened into both sides of the welding rod accommodating hole are fastened in opposite directions.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0137087 filed on October 15, 2021, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a method for fastening a welding rod and a welding device in which the welding rod is vertically fastened by the method, and more particularly to a method for fastening a welding rod that can fix the welding rod vertically to a welding surface and reduce a spatter phenomenon in which metal particles are scattered around the welded part due to an inaccurate welding angle during welding, and a welding device in which the welding rod is vertically fastened by the method. [Background technology]

[0003] As technological development and demand for mobile devices and automobiles has increased explosively, much research has been conducted on secondary batteries having high energy density, discharge voltage, and excellent output stability. Examples of such secondary batteries include lithium secondary batteries such as lithium-sulfur batteries, lithium ion batteries, and lithium ion polymer batteries. In addition, such secondary batteries can be classified into cylindrical, square, pouch, etc., depending on their shapes.

[0004] In addition, the secondary battery is formed by stacking electrode assemblies including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and is housed in a battery case together with an electrolyte. The electrode assemblies housed in the battery case can be specifically classified into a jelly-roll type in which a separator is interposed between a sheet-like positive electrode and a sheet-like negative electrode coated with an active material and the electrode assemblies are wound up, a stack type in which a number of positive electrodes and anodes are stacked in sequence with a separator interposed therebetween, and a stack / folding type in which a stack type unit cell is wound up around a long separator.

[0005] In addition, at one end of an electrode (positive electrode, negative electrode) of such a secondary battery (particularly, a secondary battery including a stack-type electrode assembly), an electrode tab connected to a lead portion that connects the electrode to an external terminal is provided so as to protrude from one side of the electrode assembly. At this time, the lead portion and the electrode tab are mainly connected by a welding method such as resistance welding (welding in which a joint is semi-melted by resistance heat generated by passing a large current through a joint of a base material and then pressure is applied to join the joint), laser welding, ultrasonic welding, etc.

[0006] In the case of a cylindrical secondary battery, the negative electrode tab is resistance-welded to a can, so that the can serves as a negative electrode terminal. FIG. 1 is a schematic side cross-sectional view of a typical cylindrical secondary battery. To explain the cylindrical secondary battery in more detail, as shown in FIG. 1, a cylindrical secondary battery 100 includes an electrode assembly 110 including a positive electrode 111, a negative electrode 113, and a separator, a can 120 that houses the electrode assembly 110 and has an opening at its upper end, and a cap assembly 130 that closes or closes the opening at the upper end of the can 120. A positive electrode tab 115 is connected to the positive electrode 111 of the electrode assembly 110, and the positive electrode tab 115 is connected to the cap assembly 130 by welding. A negative electrode tab 117 is connected to the negative electrode 113 of the electrode assembly 110, and the negative electrode tab 117 is connected to the bottom of the can 120 by resistance welding.

[0007] Fig. 2 is a schematic diagram of a state before the negative electrode tab of a conventional cylindrical secondary battery is resistance-welded to a can, and Fig. 3 is a schematic diagram of a state in which a welding rod is inserted into a conventional cylindrical secondary battery to weld the negative electrode tab to the can. As shown in Figs. 1 and 2, the negative electrode tab 117 of a conventional cylindrical secondary battery 100 is connected to the negative electrode and extends to the lower end of the electrode assembly 110. The negative electrode tab 117 is electrically connected to the bottom surface of the can 120 through resistance welding, as shown in Fig. 3.

[0008] To explain this in more detail, first, the electrode assembly 110 is placed inside the can 120 through the top opening of the can 120 as shown in Fig. 2. Then, in order to weld the negative electrode tab 117 to the bottom of the can 120 as shown in Fig. 3, a welding rod 220 is inserted into a hollow formed in the center of the electrode assembly 110 through the top opening of the can 120, and then the negative electrode tab 117 and the bottom of the can 120 are welded and fixed by the welding rod 220 inserted inside the can 120 and the welding member 150 provided on the outside of the can 120.

[0009] However, when resistance welding the negative tab to the can as described above, if the welding angle is not correct, spattering can occur, in which molten metal particles scatter around the welded part, which can lead to low voltage defects. This is due to the influence of the perpendicularity of the welding rod. If the welding surface of the welding rod and the welded object (i.e., the negative tab and the can) is not perpendicular (i.e., if the perpendicularity is distorted), the contact area decreases, and spattering occurs due to overmelting caused by the increased heat generation.

[0010] FIG. 4 is a top perspective view of a conventional welding device equipped with a welding rod, and FIG. 5 is a plan view of the conventional welding device equipped with a welding rod. In the past, a welding device having the configuration shown in FIG. 4 and FIG. 5 has been used to weld a negative electrode tab of a cylindrical secondary battery to the bottom surface of a can. That is, the conventional welding device 200 shown in FIG. 4 and FIG. 5 is a device in which a welding rod 220 and a welding rod fixing block 240 for accommodating the welding rod 220 are fastened together, and the welding rod fixing block 240 has a welding rod accommodating hole 242 formed therein, and a fixing screw 244 for fastening the welding rod accommodating hole 242 is provided to support the welding rod 220 (reference numeral 260 in FIG. 4 is a stopper). In other words, the conventional welding rod fastening is performed by inserting the welding rod 220 into the welding rod accommodating hole 242 of the welding rod fixing block 240 and then fastening the welding rod accommodating hole 242 with a fixing screw 244.

[0011] That is, in the past, a negative electrode tab of a cylindrical secondary battery is welded to the bottom of a can using a welding device as shown in Figures 4 and 5. However, when a welding rod 220 is fastened by fastening a welding rod receiving hole 242 with a single fastening screw 244 as in the past, the welding rod fixing block 240 is distorted in the fastening direction due to the fastening force (i.e., the fastening force), causing a positional deformation. As a result, the welding rod 220 fastened to the welding rod fixing block 240 is also distorted, causing a problem of being positioned asymmetrically with respect to the ground. The phenomenon in which the welding rod fixing block 240 and the welding rod 220 are distorted at the intended position (vertical with respect to the ground) is caused by the fact that the fastening screw 244 is fastened in only one direction.

[0012] Fig. 6 is a diagram showing a state in which a welding rod inserted into a typical cylindrical secondary battery is not fixed perpendicular to the welding surface, causing metal particles to scatter around the welded part. As shown in Fig. 6, when the welding rod 220 is distorted, the welding surface between the welding rod 220 and the workpiece (i.e., the negative electrode tab 117 and the can) is not perpendicular, and the contact area is reduced, causing overmelting due to an increase in the amount of heat generated, resulting in a sputtering phenomenon in which metal particles scatter around the welded part.

[0013] Therefore, there is a need for a method of fastening a welding rod that can fix the welding rod perpendicular to the welding surface and reduce the occurrence of spatter during welding, and for a welding device in which the welding rod is fastened perpendicularly. Summary of the Invention [Problem to be solved by the invention]

[0014] Therefore, an object of the present invention is to provide a welding rod fastening method that can fix a welding rod perpendicular to a welding surface and reduce the spatter phenomenon in which metal particles are scattered around the welded part due to an inaccurate welding angle during welding, and a welding device in which a welding rod is fastened perpendicularly by the method. [Means for solving the problem]

[0015] In order to achieve the above object, the present invention provides a method for fastening a welding rod to a welding rod fixing block having a welding rod accommodating hole formed therein, the method comprising: (a) inserting the welding rod into the welding rod accommodating hole of the welding rod fixing block; and (b) fastening a fixing screw into each of the spaces on both sides of the welding rod accommodating hole based on the welding rod to tighten the welding rod accommodating hole, wherein the fixing screws fastened into each of the spaces on both sides of the welding rod accommodating hole are fastened in opposite directions to each other.

[0016] The present invention also provides a welding device used in the above-mentioned welding rod fastening method, comprising: a welding rod; a welding rod fixing block having a welding rod accommodating hole for accommodating the welding rod; and two fixing screws for fastening the welding rod accommodating hole, the two fixing screws being arranged so that their fastening directions are opposite to each other. Effect of the Invention

[0017] The welding rod fastening method according to the present invention and the welding device in which the welding rod is fastened vertically thereby have the advantage that the welding rod is fixed perpendicular to the welding surface, thereby reducing the spatter phenomenon in which metal particles are scattered around the welded area due to the welding angle being incorrect during welding. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of a side cross section of a typical cylindrical secondary battery. [Diagram 2] 1 is a schematic diagram of a negative electrode tab of a typical cylindrical secondary battery before resistance welding to a can. [Diagram 3] FIG. 1 is a schematic diagram showing how a welding rod is inserted into a typical cylindrical secondary battery to weld a negative electrode tab to a can. [Figure 4] FIG. 1 is a top perspective view of a conventional welding device equipped with a welding rod. [Diagram 5] FIG. 1 is a plan view of a typical welding device equipped with a welding rod. [Figure 6]1 is a diagram showing how a welding rod inserted into a typical cylindrical secondary battery is not fixed perpendicular to the welding surface, causing metal particles to scatter around the welded portion. FIG. [Figure 7] FIG. 2 is a top perspective view showing how two fixing screws are tightened in opposite directions to fasten a welding rod perpendicular to the ground in a welding device according to an embodiment of the present invention. [Figure 8] FIG. 2 is a top perspective view showing how two fixing screws are tightened in opposite directions to fasten a welding rod perpendicular to the ground in a welding device according to an embodiment of the present invention. [Figure 9] FIG. 9 is a front view showing a state in which two fixing screws are inserted into the welding rod fixing block according to FIG. 7 or FIG. 8, and the welding rod is fastened perpendicular to the ground reference. [Figure 10] FIG. 2 is a plan view showing a state in which a welding rod is fastened perpendicular to the ground. BEST MODE FOR CARRYING OUT THEINVENTION

[0019] The present invention will now be described in detail with reference to the accompanying drawings.

[0020] Fig. 7 and Fig. 8 are top perspective views showing how two fixing screws are tightened in opposite directions to fasten a welding rod vertically relative to the ground in a welding device according to an embodiment of the present invention, Fig. 7 corresponds to a state in which two fixing screws are tightened outward in one embodiment of the present invention, and Fig. 8 corresponds to a state in which two fixing screws are tightened inward in another embodiment of the present invention. Fig. 9 is a front view showing a state in which two fixing screws are inserted into the welding rod fixing block in Fig. 7 or Fig. 8 and the welding rod is fastened vertically relative to the ground, and Fig. 10 is a plan view looking down on the state in which the welding rod is fastened vertically relative to the ground.

[0021] 7 to 10, the method of fastening a welding rod according to the present invention is a method of fastening a welding rod 320 to a welding rod fixing block 340 having a welding rod accommodating hole 342 formed therein (in a direction perpendicular to the ground), and includes the steps of (a) inserting the welding rod 320 into the welding rod accommodating hole 342 of the welding rod fixing block 340, and (b) fastening fixing screws 344a, 344b in both side spaces of the welding rod accommodating hole 342 based on the welding rod 320 to tighten the welding rod accommodating hole 342, and is characterized in that the fixing screws 344a, 344b fastened in both side spaces of the welding rod accommodating hole 342 are fastened in opposite directions to each other.

[0022] Most secondary batteries require a process of welding electrode tabs, and in particular, in cylindrical secondary batteries, the negative tab is resistance-welded to the can so that the can serves as the negative terminal, and the welding process is important in the assembly process of secondary batteries. However, as shown in Figs. 4 and 5, if the welding rod 220 is fastened by only one fastening screw 244, the welding rod fixing block 240 and the welding rod 220 fastened thereto are distorted by the fastening force tightened in only one direction, and the welding rod 220 is located asymmetrically with respect to the ground as shown in Fig. 6. As a result of the welding rod 220 being distorted in this way, the welding surface of the welding rod 220 and the workpiece (i.e., the negative tab 117 and the can) is not perpendicular, and the contact area is reduced, and a spattering phenomenon occurs in which metal particles are scattered around the welded part due to overmelting caused by an increase in heat generation.

[0023] Therefore, the applicant has invented a method for fastening a welding rod that can fix the welding rod perpendicular to the welding surface and reduce the occurrence of spatter during welding, and a welding device in which the welding rod is fastened perpendicularly using this method.

[0024] Referring again to Figs. 7 to 10, the method for fastening a welding rod according to the present invention will be described. The method for fastening a welding rod according to the present invention is a method for fastening a welding rod 320 to a welding rod fixing block 340 having a welding rod accommodating hole 342 formed therein in a direction perpendicular to the plane of the drawing, and is characterized in that, unlike ordinary welding equipment, two or more fixing screws are used for fastening the welding rod instead of one.

[0025] In order to fasten the welding rod according to the present invention, first, the welding rod 320 is inserted into the welding rod receiving hole 342 of the welding rod fixing block 340 to position the welding rod 320 in a vertical direction based on the ground (step a). This is a process that is similarly applied to the conventional method of fastening a welding rod, so a detailed description will be omitted. The shape and material of the welding rod 320 and the welding rod fixing block 340 may be the same as those of the conventional method. In addition, it will be apparent that the stopper 360 provided to enclose the welding rod 320 at the lower part of the welding rod fixing block 340 after the welding rod 320 is inserted into the welding rod receiving hole 342 of the welding rod fixing block 340 is also the same as that of the conventional method. For reference, the stopper 360 may play a role of lightly holding the welding rod 320 while the welding rod 320 is fastened to the welding rod fixing block 340.

[0026] After inserting the welding rod 320 into the welding rod receiving hole 342 of the welding rod fixing block 340 and positioning the welding rod 320 in a vertical direction relative to the ground, a process of fastening the welding rod receiving hole 342 by fastening fixing screws 344a and 344b into both sides of the welding rod receiving hole 342 based on the welding rod 320 on one side of the welding rod fixing block 340 is performed (step b). The process of inserting fixing screws into the side of the welding rod fixing block to fasten the welding rod receiving hole is the same as that of the conventional process.

[0027] However, unlike the conventional welding rod fastening method in which the welding rod is fastened using only one fastening screw, the present invention uses two or more fastening screws (at least two fastening screws 344a, 344b). And, the present invention inserts the same number of fastening screws into each of the spaces on both sides of the welding rod receiving hole 342 based on the welding rod 320, at least one fastening screw. That is, in order to apply the same fastening force on both sides based on the welding rod 320, the same number of fastening screws must be inserted into each of the spaces on both sides of the welding rod receiving hole 342 based on the welding rod 320. From the viewpoint of process simplification and efficiency, as shown in Figs. 7 to 10, it is preferable to insert one fastening screw into each of the spaces on both sides of the welding rod receiving hole 342 based on the welding rod 320, but if a stronger fastening force is required, additional fastening screws can be inserted. However, in this case, it is of course necessary to insert the same number of fastening screws into each of the spaces on both sides based on the welding rod 320.

[0028] 9, in the present invention, an even number of fixing screws are inserted and positioned on the same line perpendicular to the central axis of the welding rod 320. Also, the fixing screws 344a, 344b fastened to both sides of the welding rod 320 should be positioned at the same distance from the central axis of the welding rod 320. In particular, the fixing screws 344a, 344b inserted into the spaces on both sides of the welding rod receiving hole 342 based on the welding rod 320 should be tightened in opposite directions.

[0029] That is, the fixing screws 344a, 344b inserted on both sides of the welding rod 320 can be inserted and fastened by tightening them inward as shown in Fig. 7, or can be inserted and fastened by tightening them inward as shown in Fig. 8. In other words, if one of the two fixing screws 344a, 344b is tightened in the outward direction and the other is tightened in the inward direction, the two fixing screws 344a, 344b end up rotating in the same direction, so that the welding rod 320 and the welding rod fixing block 340 cannot be perpendicular to the ground, which causes the same problem as in the conventional welding rod fastening method. Therefore, the fixing screws 344a, 344b fastened on both sides of the welding rod 320 must be inserted and fastened to the welding rod fixing block 340 by tightening them in opposite directions. In addition, according to this method, the welding rod 320 is maintained vertical to the ground even while the two fixing screws 344a and 344b are being tightened or after they are tightened and inserted. Even if not, the distortion of the welding rod 320 due to the tightening of the fixing screws 344a and 344b is minimized.

[0030] However, even if the fixing screws 344a, 344b inserted on both sides of the welding rod 320 are tightened in opposite directions as described above, if only one of the fixing screws 344a, 344b is tightened first, the welding rod 320 and the welding rod fixing block 340 will not be perpendicular to the ground, and in this case, the same problems as those in the conventional welding rod tightening method may occur. Therefore, it is preferable to tighten the fixing screws 344a, 344b inserted on both sides of the welding rod 320 at the same time.

[0031] As described above, when the welding rod 320 is fixed perpendicular to the ground or the welding surface, welding is performed toward the object to be welded. Meanwhile, the above description is limited to the application of welding the negative electrode tab of a cylindrical secondary battery to the bottom surface of a can, but it is of course useful for welding the lead part and electrode tab of a stacked electrode assembly. In addition, it is of course applicable to all fields where welding (especially resistance welding) is required, and in particular where it is difficult to maintain the perpendicularity of the welding rod, spattering occurs, and this causes problems in product quality, etc.

[0032] Next, a welding device according to the present invention will be described. Referring again to Fig. 7 to Fig. 10, the welding device 300 according to the present invention is a welding device used in the above-described welding rod fastening method (or a welding device in which a welding rod 320 and a welding rod fixing block 340 are fastened by the welding rod fastening method), and is characterized in that it includes a welding rod 320 (positioned to be fixed vertically relative to the ground), a welding rod receiving hole 342 for receiving the welding rod 320, and a welding rod fixing block 340 having two fixing screws 344a and 344b for fastening the welding rod receiving hole 342, and the two fixing screws 344a and 344b are provided so that their fastening directions are opposite to each other.

[0033] The welding rod 320 is screwed and accommodated in the welding rod accommodation hole 342 of the welding rod fixing block 340. Although the upper end of the welding rod 320 is shown to protrude above the top cross section of the welding rod fixing block 340 in Figs. 7 to 9, it is not necessarily accommodated in the welding rod fixing block 340 in such a structure. That is, it is sufficient that the upper end of the welding rod 320 is only above the fixing screws 344a and 344b. This is because the welding rod 320 only needs to be fixed through the fixing screws 344a and 344b. And, since the lower end of the welding rod 320 is used to weld between the objects to be welded, it is preferable to provide it as close to the objects to be welded as possible even if the welding rod 320 is perpendicular to the ground or the welding surface.

[0034] The welding rod fixing block 340 is formed with a welding rod accommodating hole 342 for accommodating the welding rod 320 and two screw grooves into which two fixing screws 344a and 344b for fastening the welding rod accommodating hole 342 can be inserted. As shown in Figs. 7, 8 and 10, the welding rod accommodating hole 342 may be formed to open at one end of a side surface of the welding rod fixing block 340. Here, the side surface of the welding rod fixing block 340 may be a surface connected to a side surface of the welding rod fixing block 340 into which the fixing screws 344a and 344b are inserted, i.e., any surface that does not face the side surface of the welding rod fixing block 340 into which the fixing screws 344a and 344b are inserted.

[0035] Also, the welding rod receiving hole 342 may be formed to open at one end of a side surface of the welding rod fixing block 340 and drilled up and down to the inside so that the welding rod 320 can be inserted and screwed to the inside of the welding rod fixing block 340. At this time, the distance from one end of a side surface of the welding rod fixing block 340 to the inside may vary depending on the position where the welding rod 320 is positioned and the positions where the two fixing screws 344a and 344b are inserted, but must be at least large enough to allow both of the two fixing screws 344a and 344b to be inserted.

[0036] That is, the welding rod receiving hole 342 must be formed to the inside of the position of the fixing screw (344a in FIG. 10) inserted most inwardly based on the side opening where the welding rod receiving hole 342 is formed. However, this is merely an example, and there is no special limitation on the shape of the welding rod receiving hole 342 as long as the welding rod 320 can be received and fastened and fixed by two fixing screws 344a and 344b. There is no. Also, the welding rod receiving hole 342 may be formed with a welding rod fixing groove 343 from the upper end to the lower end so that the welding rod 320 is stably fixed without moving left and right in the welding rod receiving hole 342 as shown in FIG.

[0037] Also, the two fixing screws 344a, 344b should be disposed on both sides of the welding rod 320, respectively, and should be disposed so as to cross both sides of the space of the welding rod receiving hole 342, respectively, based on the welding rod 320. Preferably, the two fixing screws 344a, 344b are disposed so as to cross the welding rod receiving hole 342 in a direction perpendicular to the central axis of the welding rod 320, and are disposed on the same line perpendicular to the central axis of the welding rod 320, as shown in Fig. 9. In other words, the two fixing screws 344a, 344b are disposed so as to be fastened on the outer circumferential surface of the welding rod fixing block 340, and as described above, the two fixing screws 344a, 344b pass through one side wall of the welding rod receiving hole 342 and are fixed to the other side wall by screw coupling.

[0038] In addition, the two fixing screws 344a, 344b are located at the same distance from the central axis of the welding rod 320, and are tightened in opposite directions. For example, the fixing screws 344a, 344b may be tightened outwardly as shown in FIG. 7, or may be tightened inwardly as shown in FIG. 8. In addition, a stopper 360 may be disposed at the lower part of the welding rod fixing block 340, surrounding the welding rod 320. As described above, the stopper 360 may play a role of lightly supporting the welding rod 320 while the welding rod 320 is being fastened to the welding rod fixing block 340.

[0039] Although the present invention has been described above through preferred embodiments, it will be readily understood by those skilled in the art to which the present invention pertains that the present invention is not limited thereto, and various modifications and variations are possible without departing from the concept and scope of the claims set forth below. [Explanation of symbols]

[0040] 100: cylindrical secondary battery (110: electrode assembly, 111: positive electrode, 113: negative electrode, 115: positive electrode tab, 117: negative electrode tab, 120: can, 130: cap assembly, 150: welding member) 200, 300: Welding equipment 220, 320: welding rod 240, 340: Welding rod fixing block 242, 342: Welding rod storage hall 343: Welding rod fixing groove 244, 344: Fixing screw 260, 360: Stopper

Claims

1. A method for fastening a welding rod to a welding rod fixing block having a welding rod receiving hole, comprising: (a) inserting the welding rod into the welding rod receiving hole of the welding rod fixing block; and (b) fastening the welding rod receiving hole by fastening a fixing screw into each of the spaces on both sides of the welding rod receiving hole based on the welding rod; Including, The method for fastening a welding rod, comprising the steps of: fastening the fixing screws fastened to the spaces on both sides of the welding rod receiving hole in such a manner that the fastening directions are opposite to each other.

2. 2. The method of claim 1, wherein the fixing screws are fastened to both sides of the welding rod at the same time to fix the welding rod.

3. 3. The method for fastening a welding rod according to claim 1, wherein the fixing screws fastened on both sides of the welding rod are positioned at the same distance from a central axis of the welding rod.

4. 2. The method of claim 1, wherein distortion of the welding rod is minimized by tightening the fixing screw.

5. 2. The method of claim 1, wherein the method is used to weld a negative electrode tab of a cylindrical secondary battery to a bottom surface of a can.

6. A welding device used in the welding rod fastening method of claim 1, Welding rods, and a welding rod fixing block including a welding rod receiving hole for receiving the welding rod and two fixing screws for fastening the welding rod receiving hole; Including, The welding device is characterized in that the two fixing screws are provided so that their tightening directions are opposite to each other.

7. The welding device according to claim 6, wherein the two fixing screws are provided to cross both sides of the welding rod receiving hole with respect to the welding rod.

8. The welding device according to claim 7, wherein the two fixing screws are provided to cross the welding rod receiving hole in a direction perpendicular to the central axis of the welding rod and are positioned on the same line perpendicular to the central axis of the welding rod.

9. The welding device according to any one of claims 6 to 8, wherein the two fixing screws are positioned at the same distance from a central axis of the welding rod.

10. 7. The welding device according to claim 6, wherein the welding rod receiving hole is formed by opening at one end of a side surface of the welding rod fixing block and drilling vertically to an inside.

11. 11. The welding device according to claim 10, wherein the welding rod receiving hole is formed to a position inside a point where an innermost fixing screw is located based on a side opening in which the welding rod receiving hole is formed.

12. The welding device according to claim 10, wherein the welding rod receiving hole has a welding rod fixing groove formed from an upper end to a lower end.

13. 7. The welding device according to claim 6, wherein the two fixing screws pass through one side wall of the welding rod receiving hole and are fixed to the other side wall by screw connection.

14. 7. The welding device according to claim 6, wherein the two fixing screws are provided so as to be tightenable on an outer circumferential surface of the welding rod fixing block.

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