Patent Publication Number: US-2019193190-A1

Title: Resistance-Welding Equipment

Description:
CROSS REFERENCE TO THE RELATED APPLICATION 
     This application is a continuation application, under 35 U.S.C.§111(a), of international application No. PCT/JP2017/031776, filed Sep. 4, 2017, which claims priority to Japanese patent application No. 2016-172957, filed Sep. 5, 2016, the disclosure of which are incorporated by reference in their entirety into this application. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to resistance-welding equipment that performs resistance welding on a workpiece while interposing and pressing the workpiece between a pair of welding electrodes 
     Description of Related Art 
     Hitherto, resistance-welding equipment that performs resistance welding by applying a current to a pair of welding electrodes while interposing and pressing a metallic workpiece between the welding electrodes, has been known. Generally, in the resistance welding, a large current is applied for a short time, and a nugget (alloy layer) is formed by using heat generation due to resistance of the metal, thereby achieving melt-joining Since the welding is carried out in a short time, the welding can be efficiently performed and can be less likely to thermally influence the material. 
     For example, during production of a battery in which battery components are housed in a tubular container, it is necessary to weld a terminal of each battery component and an inner bottom surface of the container that are workpieces. In this case, interposing an intermediate electrode extending in the up-down direction between a pair of upper and lower welding electrodes, inserting the intermediate electrode into the container, and welding the workpieces, are known (for example, Patent Document 1). 
     RELATED DOCUMENT 
     Patent Document 
     [Patent Document 1] JP Laid-open Patent Publication No. 2009-252350 
     SUMMARY OF THE INVENTION 
     In the above conventional apparatus, in some cases, application of a particularly large current such as 10000 amperes (A) of current is required, or increase in speed of a production line, continuous production, or the like is requested for improving the production efficiency. In such a case, due to the large current, the increase in speed, or the like, as shown in  FIG. 7 , heat is accumulated in the welding electrode or the intermediate electrode, whereby variations in welding performance occur, or the wear degree of the electrode is increased, causing deterioration of the electrode, in some cases. In addition, in the case where a workpiece is a metal such as aluminum, aluminum is melted and scattered to adhere to each electrode, whereby the wear degree of each electrode is further increased in some cases. 
     In such a case, the service life of each electrode is shortened, and thus the frequency of electrode replacement is increased, and time for the replacement is taken each time the replacement is performed. Therefore, there is a problem in that it is difficult to improve the production efficiency in resistance welding. Thus, resistance-welding equipment that is able to easily improve production efficiency by reducing the frequency of electrode replacement is desired. 
     An object of the present invention is to provide resistance-welding equipment that solves the above problem and that is able to easily improve production efficiency by reducing the frequency of electrode replacement even when application of a large current, increase in speed of a production line, or the like is required. 
     Resistance-welding equipment according to the present invention includes an equipment main body including: a pair of upper and lower welding electrodes provided so as to be movable up and down and configured to weld a workpiece interposed therebetween with a current applied thereto; and a pressing unit configured to press the workpiece via the upper and lower welding electrodes during the welding. 
     The equipment main body includes an intermediate electrode set disposed between the upper and lower welding electrodes and provided at at least one of the upper and lower welding electrode sides, in which the intermediate electrode set includes a plurality of intermediate units, each intermediate unit having an intermediate electrode set jig and an intermediate electrode attachable to and detachable from the intermediate electrode set jig, and is configured as a rotary type in which the plurality of intermediate units are provided so as to be rotatable in a circumferential direction such that the plurality of intermediate units sequentially stop at a welding position that is aligned with the upper and lower welding electrodes in an up-down direction. The intermediate electrode set is configured to resistance-weld the workpiece, while pressing the workpiece by the pressing unit, via the intermediate electrode of the intermediate unit at the welding position. 
     According to this configuration, a workpiece is subjected to resistance welding by sequentially using the plurality of intermediate electrodes. Thus, the use frequency of each intermediate electrode is reduced by the number of intermediate electrodes, whereby the frequency of electrode replacement can be reduced. In addition, since each intermediate electrode is attachable and detachable, the time for replacement of the intermediate electrode can be also shortened. Even in the case where application of a large current, increase in speed of a production line, or the like is required, the production efficiency can be easily improved. 
     In the present invention, the intermediate electrode set may include a plurality of pairs of upper and lower intermediate units, and may be configured to resistance-weld, via the upper and lower intermediate electrodes at the welding position being supplied with electric power through the upper and lower welding electrodes, a workpiece interposed between the upper and lower intermediate electrodes. In this case, a workpiece is subjected to resistance welding via all the intermediate electrodes, and thus the production efficiency can be further improved. 
     In a state where the intermediate electrode of the intermediate unit is stopped at the welding position, one workpiece may be subjected to resistance welding or two or more workpieces may be continuously subjected to resistance welding. In this case, the use state of each intermediate electrode can be appropriately selected in accordance with deterioration of each intermediate electrode based on a welding state or the type of the workpieces. 
     In the present invention, the welding electrode may have an electrode portion configured to surface-contact a power supply surface of the intermediate electrode such that electric power is supplied from the welding electrode to the intermediate electrode, and dimensions of a diameter D of the power supply surface of each intermediate electrode and a height H of each intermediate electrode may satisfy D/H≥1/1.2. Therefore, even if the intermediate electrodes are set in a slightly tilted state, the intermediate electrodes are immediately corrected to a standing state. Thus, the intermediate electrodes are assuredly brought into surface contact with the welding electrodes, and time for replacement can be further shortened. 
     Preferably, in the intermediate electrode set, the intermediate electrode set jig that holds the intermediate electrodes is formed with a holding hole and the intermediate electrode has a portion to be held that is inserted into the holding hole, the holding hole and the portion to be held are formed in the same tapered shapes, such that centering adjustment of the intermediate electrode with respect to the intermediate electrode set jig is performed by the portion to be held of the intermediate electrode being inserted into the holding hole of the intermediate electrode set jig. In this case, each intermediate electrode is automatically centered, so that centering work becomes easy and time for replacing the intermediate electrode can be further shortened. As a result, the production efficiency can be improved. 
     Preferably, the resistance-welding equipment includes a cooling device configured to forcedly cool each intermediate electrode at at least a welding standby position that is not the welding position. Therefore, accumulation of heat in each intermediate electrode is prevented, so that variations in welding and deterioration of each intermediate electrode due to heat accumulation can be further suppressed. In addition, preferably, electrode portions of the intermediate electrodes are provided so as to be attachable and detachable. Therefore, when the electrode portion has been worn or when the electrode portion is changed to an electrode portion formed from another material, only the electrode portion can be easily replaced. 
     Any combination of at least two constructions, disclosed in the appended claims and/or the specification and/or the accompanying drawings should be construed as included within the scope of the present invention. In particular, any combination of two or more of the appended claims should be equally construed as included within the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In any event, the present invention will become more clearly understood from the following description of preferred embodiments thereof, when taken in conjunction with the accompanying drawings. However, the embodiments and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several views, and: 
         FIG. 1  is a front view showing resistance-welding equipment according to an embodiment of the present invention; 
         FIG. 2  is a side view showing the resistance-welding equipment in  FIG. 1 ; 
         FIG. 3A  is a partially enlarged view of the resistance-welding equipment of the present invention; 
         FIG. 3B  is a partially enlarged view of the resistance-welding equipment of the present invention; 
         FIG. 3C  is a partially enlarged view of the resistance-welding equipment of the present invention; 
         FIG. 4A  is a configuration diagram showing an intermediate electrode set jig and an intermediate electrode; 
         FIG. 4B  is a configuration diagram showing an intermediate electrode set jig and an intermediate electrode; 
         FIG. 5A  is a configuration diagram showing the intermediate electrode set jig and the intermediate electrode; 
         FIG. 5B  is a configuration diagram showing the intermediate electrode set jig and the intermediate electrode; 
         FIG. 5C  is a configuration diagram showing the intermediate electrode set jig and the intermediate electrode; 
         FIG. 6  is a configuration diagram showing a contact state of a welding electrode and the intermediate electrode; and 
         FIG. 7  is a diagram showing a heat generation state during welding. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings.  FIG. 1  is a schematic configuration diagram showing resistance-welding equipment  1  according to an embodiment of the present invention. The equipment  1  is suitable for resistance welding, for which application of a large current, increase in speed of a production line or the like is needed. The equipment  1  is particularly effective for, for example, the case where, as a result of application of a large current such as 10000 amperes (A) of current or increase in speed of a production line for improving production efficiency, variations in welding performance occur due to accumulation of heat in an electrode, or the wear degree of an electrode is increased or a workpiece such as aluminum is melted and scattered to adhere to an electrode, leading to deterioration of the electrode. 
     The equipment  1  includes: an equipment main body  2  that is fixed on a mount  20 ; a control unit  3  that is disposed within the mount  20  and controls the entire equipment; and a welding power supply  4  that supplies, for example, DC power to the equipment main body  2 . A value of current to be applied to welding electrodes is set with the welding power supply  4 . 
     As shown in  FIG. 2 , the equipment main body  2  includes: a pair of upper and lower welding electrodes  5   a  and  5   b  that are provided so as to be movable up and down along a first axis Y 1  extending in the up-down direction and that weld a workpiece W interposed therebetween with a current applied thereto; upper and lower electrode holders  6   a  and  6   b  that hold the upper and lower welding electrodes  5   a  and  5   b,  respectively; and a pressing unit  7  that is disposed above the upper welding electrode  5   a  and presses the workpiece in the up-down direction via the upper and lower welding electrodes  5   a  and  5   b  during the welding. In addition, an operation panel  8  used for operating the equipment  1  is disposed at an upper portion of the equipment main body  2 . 
     An intermediate electrode set  10  is disposed between the upper and lower welding electrodes  5   a  and  5   b.  The intermediate electrode set  10  includes a plurality of pairs of upper and lower intermediate units  18   a  and  18   b  having intermediate electrode set jigs  11   a  and  11   b  and intermediate electrodes  12   a  and  12   b  that are attachable to and detachable from the intermediate electrode set jigs  11   a  and  11   b,  respectively. The plurality of intermediate units  18   a  and  18   b  are configured as a rotary type in which the intermediate units  18   a  and  18   b  are provided so as to be rotatable in the circumferential direction such that the intermediate units  18   a  and  18   b  sequentially stop at a welding position that is aligned with the upper and lower welding electrodes  5   a  and  5   b  in the up-down direction. The intermediate electrode set  10  is driven by a drive motor  9  to rotate about a second axis Y 2  that is spaced apart from the first axis Y 1  and extends parallel to the first axis Y 1  in the up-down direction. The upper and lower intermediate electrodes  12   a  and  12   b  receive a current applied from a connector  4   a  of the welding power supply  4  via the upper and lower electrode holders  6   a  and  6   b  through respective electrode portions of the upper and lower welding electrodes  5   a  and  5   b.    
     The control unit  3  performs not only control of the entire equipment but also pressing control of the pressing unit  7 , rotary control of the rotary-type intermediate electrode set  10 , etc. The operation panel  8  is provided with a switch portion, a setting portion, etc., related to operations and is also provided with a display device that displays operation content. 
     As shown in  FIG. 3B  and  FIG. 3C , the rotary-type intermediate electrode set  10  includes, for example, six upper or lower intermediate electrode set jigs  11   a  or  11   b  and six upper or lower intermediate electrodes  12   a  or  12   b,  at each of the upper and lower sides, and horizontally rotates about the second axis Y 2  in the direction indicated by the arrow as shown in  FIG. 3A . As shown in  FIG. 2 , one pair of the intermediate electrodes  12   a  and  12   b  of the plurality of the intermediate units  18   a  and  18   b  of which rotation is stopped at the welding position between the upper welding electrode  5   a  and the lower welding electrode  5   b,  and a workpiece interposed between the intermediate electrodes  12   a  and  12   b  is welded. 
     As shown in  FIG. 4A  and  FIG. 4B , the intermediate electrode set jigs  11   a  and  11   b,  which hold the intermediate electrodes  12   a  and  12   b,  respectively, has respective center portions formed with holding holes  11   d  and  11   e , which have tapered inner surfaces T 1  and T 2 , and the upper and lower intermediate electrodes  12   a  and  12   b  each have: a power supply electrode plate  15  having a power supply surface  13  and a jig attachment portion  14 ; and an electrode portion  16 . As shown in  FIG. 4A , the upper intermediate electrode  12   a  has a surface T 1  formed on a lower portion of the jig attachment portion  14  in the same tapered shape as the inner surface T 1 . The intermediate electrode  12   a  is fixed by being guided by and fitted into the tapered holding hole  11   d  in the center portion of the intermediate electrode set jig  11   a.  The intermediate electrode  12   a  is detachable from the intermediate electrode set jig  11   a  in the upward direction. 
     As shown in  FIG. 4B , the lower intermediate electrode  12   b  also has a tapered surface T 2  formed on the jig attachment portion  14 , and is fixed by being fitted into the holding hole  11   e  having the same tapered shape as the inner surface T 2  in the center portion of the intermediate electrode set jig  11   a.  The intermediate electrode  12   a  is detachable from the intermediate electrode set jig  11   a  in the upward direction. The upper and lower intermediate electrodes  12   a  and  12   b  are easily detached as described above, the intermediate electrode set  10  can be positioned by merely fitting the upper and lower intermediate electrodes  12   a  and  12   b  to the intermediate electrode set jigs  11   a  and  11   b,  and the upper and lower intermediate electrodes  12   a  and  12   b  are assuredly brought into surface contact with the upper and lower welding electrodes  5   a  and  5   b.  Thus, time for replacement can be further shortened. In this example, the intermediate electrode set  10  is positioned with the tapered holes, but a positioning pin that is not shown may be used instead of the tapered holes. 
       FIG. 5A  to  FIG. 5C  are configuration diagrams showing respective contact states of the welding electrode and the intermediate electrode. As shown in  FIG. 5A , the electrode portions of the upper and lower welding electrodes  5   a  and  5   b  are brought into surface contact with the power supply surfaces  13  of the upper and lower intermediate electrodes  12   a  and  12   b.  In the case where the diameters D of the power supply surfaces  13  of the upper and lower intermediate electrodes  12   a  and  12   b  are large and the heights H thereof are short as shown in  FIG. 5B , even in a state where the upper and lower intermediate electrodes  12   a  and  12   b  are slightly tilted, if the welding electrode  5  and the power supply surface  13  are brought into contact with each other at a point a during pressing, the upper and lower intermediate electrodes  12   a  and  12   b  are each brought into a standing state, and correction force that brings the entire power supply surface  13  into contact with the welding electrode  5  becomes large between the point α and a fulcrum β. On the other hand, in the case where the diameter D of each power supply surface  13  is small and the height H is long as shown in  FIG. 5C , the correction force becomes small. In each of the intermediate electrodes  12   a  and  12   b,  the diameter D of the power supply surface  13  and the height H preferably satisfy D/H≥1/1.2, and more preferably satisfy D/H≥1. Accordingly, the upper and lower welding electrodes  5   a  and  5   b  and the upper and lower intermediate electrodes  12   a  and  12   b  can be assuredly brought into surface contact with each other, and the diameter D of each power supply surface  13  is large, and thus it is also possible to apply a large current. 
     As shown in  FIG. 6 , the electrode portion  16  of the upper intermediate electrode  12   a  is fitted into a hole  15   a  of the power supply electrode plate  15  and fixed by a fixing screw  17 . The electrode portion  16  is positioned with the hole  15   a  of the power supply electrode plate  15 . The lower intermediate electrode  12   b  also has the same configuration. Accordingly, when the electrode portion  16  has been worn or when the electrode portion  16  is changed to an electrode portion  16  formed from another material, only the electrode portion  16  can be easily replaced. 
     In the above resistance-welding equipment  1 , the respective intermediate electrodes  12  are sequentially stopped at the welding position, for example, for the first to third times at I to III in  FIG. 3A , and different objects to be welded are welded at each time. For example, in the case of performing 1000 shots with one intermediate electrode  12 , 6000 shots can be performed with six intermediate electrodes  12  in total. In this case, the use frequency of one intermediate electrode  12  is reduced in proportion to the number of intermediate electrodes  12 , so that continuous production corresponding to the number of intermediate electrodes  12  is enabled. As a result, the replacement frequency of each intermediate electrode  12  is reduced, so that the production efficiency can be improved. 
     In a state where the intermediate electrodes  12  of the intermediate unit  18  is stopped at the welding position, one workpiece may be subjected to resistance welding or two or more workpieces may be continuously subjected to resistance welding. Alternatively, each intermediate electrode  12  may be intermittently stopped at the welding position in such a manner that one or more intermediate electrodes are skipped. In this manner, the use state of each intermediate electrode can be appropriately selected in accordance with deterioration of each intermediate electrode based on a welding state or the type of the workpieces. 
     A welding interval is increased by the number of intermediate electrodes  12 , heat of the intermediate electrodes that are not used for welding during the welding interval is dissipated, and accumulation of heat in each welding electrode (intermediate electrode) is suppressed. Thus, even with natural cooling, it is possible to suppress variations in welding performance and deterioration of the welding electrode due to heat thereof 
     Furthermore, a cooling device such as a fan that is not shown may be provided, and the intermediate electrodes  12  at welding standby positions that are not the welding positions may be forcedly cooled, or the intermediate electrodes  12  that are detached may be cooled in this state. Accordingly, deterioration due to heat can be suppressed, resulting in further reduction in frequency of electrode replacement. 
     As described above, in the present invention, since the rotary-type intermediate electrode set  10  in which the plurality of intermediate electrodes  12  are rotatable in the circumferential direction is provided, workpieces are subjected to resistance welding using the plurality of intermediate electrodes  12 . Thus, the use frequency of each intermediate electrode  12  is reduced by the number of intermediate electrodes  12 , whereby the frequency of electrode replacement can be reduced. In addition, since each intermediate electrode  12  is attachable and detachable, the time for replacement of the intermediate electrode  12  can be also shortened. Even in the case where application of a large current, increase in speed of a production line or the like is required, the production efficiency can be easily improved. 
     In this embodiment, as shown in  FIG. 3A ,  FIG. 3B ,  FIG. 4A , and  FIG. 4B , six intermediate units  18   a  and six intermediate units  18   b  are provided between the upper and lower welding electrodes  5   a  and  5   b  at the upper and lower sides, respectively. However, each of the numbers of intermediate units  18   a  and  18   b  is not limited to this number and may be less than 6 or may be 7 or more. In addition, the upper intermediate units  18   a  may be provided only at the upper welding electrode  5   a  side, and no lower intermediate units  18   b  may be provided, or the lower intermediate units  18   b  may be provided only at the lower welding electrode  5   b  side, and no intermediate units  18   a  may be provided. Between these cases, in the former case, a workpiece is welded between the upper intermediate electrode  12   a  of the upper intermediate unit  18   a  and the lower welding electrode  5   b,  and in the latter case, a workpiece is welded between the upper welding electrode  5   a  and the lower intermediate electrode  12   b  of the lower intermediate unit  18   b.    
     Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings which are used only for the purpose of illustration, those skilled in the art will readily conceive numerous changes and modifications within the framework of obviousness upon the reading of the specification herein presented of the present invention. Accordingly, such changes and modifications are, unless they depart from the scope of the present invention as delivered from the claims annexed hereto, to be construed as included therein. 
     REFERENCE NUMERALS 
       1  . . . Rotary-type resistance-welding equipment 
       2  . . . Equipment main body 
       3  . . . Control unit 
       4  . . . Welding power supply 
       5   a,    5   b  . . . Welding electrode (upper, lower) 
       7  . . . Pressing unit 
       10  . . . Intermediate electrode set 
       11  ( 11   a,    11   b ) . . . Intermediate electrode set jig (upper, lower) 
       12  ( 12   a,    12   b ) . . . Intermediate electrode (upper, lower) 
       18  ( 18   a,    18   b ) . . . Intermediate unit (upper, lower) 
     W . . . Workpiece