JP5449928B2 - Spot welding equipment - Google Patents

Description

  The present invention relates to a spot welding apparatus and a spot welding method.

  Conventionally, for example, spot welding is frequently used for assembling stainless steel vehicles. In spot welding, for example, a base material to be welded, such as a thin steel plate, is sandwiched between a pair of electrodes, and current is applied while pressing the base material with the electrodes. (See, for example, Patent Document 1).

Japanese Patent No. 2953354

  In the spot welding described above, the electrode bites into the base material due to the applied pressure, and the surface of the base material is dented, resulting in indentation. On the other hand, it is also conceivable to reduce the biting of the electrode into the base material by using a copper plate electrode or the like for one of the electrodes. However, when the base material is a thin plate, although the dent of the welded portion is reduced, the entire base material may be distorted due to lifting and deformation around the welded portion. When a stainless steel vehicle is manufactured using spot welding, since the stainless steel vehicle is generally unpainted, there is a problem in that the appearance of the appearance deteriorates if the indentation or distortion of the base material due to spot welding is noticeable.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a spot welding apparatus and a spot welding method capable of suppressing indentation in a welded portion and deformation of a base material around the welded portion. To do.

  In order to solve the above problems, a spot welding apparatus according to the present invention is a spot welding apparatus that sandwiches a laminated steel sheet with a pair of electrodes and energizes the sheet steel while pressing the sheet steel with the electrodes to form a welded portion. The electrode has a constricted part that reduces the current-carrying region by reducing the current-carrying region, and the welded part including the welded part passes the current constricted by the constricted part toward the thin steel plate. And a pressurizing part that pressurizes the liquid.

  In this spot welding device, the current-carrying region of the current is narrowed by the narrowed portion so that the nugget diameter of the welded portion is smaller than the electrode diameter and welding is performed while a sufficient area around the welded portion including the welded portion is pressurized by the pressure portion. The part can be formed. Therefore, the amount of indentation in the welded portion and the deformation of the base material around the welded portion can be suppressed at the same time. By using this spot welding device, for example, for welding an outer plate of a stainless steel vehicle, it becomes possible to manufacture a vehicle in which indentations and distortions are not noticeable.

  Moreover, it is preferable that a pressurization part is the same material as the main-body part of an electrode. In this case, since the cooling function around the welded portion by the pressurizing portion can be sufficiently ensured, a healthy nugget can be formed.

  Moreover, it is preferable that the aperture part is formed by an insulating plate provided with an opening having a smaller diameter than the electrode diameter. In this case, the aperture can be more reliably formed by the opening of the insulating plate.

  The insulating plate is preferably made of a phenol resin. In this case, the heat resistance and pressure resistance of the insulating plate can be sufficiently secured.

  The electrode body is provided with a recess having substantially the same diameter as the opening of the insulating plate, while the pressurizing portion is provided with a protrusion corresponding to the recess, and the electrode is provided with the opening of the insulating plate. It is preferable that the convex part of the pressurizing part through which is passed is engaged with the concave part of the main body part of the electrode. In this case, an electrode having a throttle part and a pressure part can be easily configured. In addition, since the insulating plate and the pressurizing portion can be freely attached to and detached from the main body portion of the electrode, the insulating plate and the pressurizing portion can be exchanged as necessary.

  Further, the spot welding method according to the present invention is a spot welding method in which a laminated steel sheet is sandwiched between a pair of electrodes, and the thin steel sheet is energized while being pressed with the electrodes to form a welded portion. It is characterized in that the welded portion is formed while pressurizing around the welded portion including the welded portion while reducing the nugget diameter of the welded portion smaller than the electrode diameter.

  In this spot welding method, the current-carrying region of the current is narrowed by the narrowed portion so that the nugget diameter of the welded portion is smaller than the electrode diameter, and a sufficient area around the welded portion including the welded portion is pressed by the pressurizing portion. The part can be formed. Therefore, the amount of indentation in the welded portion and the deformation of the base material around the welded portion can be suppressed at the same time. By using this spot welding method, for example, for welding an outer plate of a stainless steel vehicle, it becomes possible to manufacture a vehicle in which indentation and distortion are not noticeable.

  ADVANTAGE OF THE INVENTION According to this invention, the deformation | transformation of the indentation in a welding part and the base material around a welding part can be suppressed.

It is a figure which shows one Embodiment of the spot welding apparatus and spot welding method which concern on this invention. It is a disassembled perspective view which shows the structure of the electrode of the spot welding apparatus shown in FIG. It is a figure which shows the state of the welding part at the time of using the conventional spot welding apparatus, and a base material.

  Hereinafter, preferred embodiments of a spot welding apparatus and a spot welding method according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of a spot welding apparatus and a spot welding method according to the present invention. As shown in the figure, the spot welding apparatus 1 sandwiches the overlapped thin steel plates with a pair of electrodes 2 and 3 and energizes the thin steel plates with pressure by these electrodes 2 and 3 to form a welded portion W. Device. In this embodiment, the outer plates 4 and 5 having a thickness of about 1.5 mm used for forming a stainless steel vehicle are illustrated as thin steel plates to be welded.

  The electrodes 2 and 3 of the spot welding apparatus 1 have a cylindrical shape with a diameter of about 30 mm as a whole. As shown in FIGS. 1 and 2, the electrode 2 includes a main body portion 11, a pressurizing portion 12 provided at the tip of the main body portion 11, and an insulating plate disposed between the main body portion 11 and the pressurizing portion 12. 13. The main body 11 is made of, for example, chrome copper, and a cylindrical recess 11b having an inner diameter of about 5 mm is provided at the center of the front end surface 11a of the main body 11. A screw groove is formed on the inner wall surface of the recess 11b.

  The pressurizing unit 12 is formed of, for example, chrome copper, like the main body unit 11. The thickness of the pressurizing unit 12 is, for example, about 5 mm, and the central part of the base end surface 12a of the pressurizing unit 12 has a columnar shape with an outer diameter of about 5 mm corresponding to the recess 11b of the main body unit 11. The convex portion 12b is provided. The outer wall surface of the convex portion 12b is provided with a thread groove corresponding to the thread groove of the concave portion 11b. By pressing the convex portion 12b into the concave portion 11b, the pressurizing portion 12 is attached to the main body portion 11. It can be installed.

  The insulating plate 13 is formed of, for example, a phenol resin that is excellent in heat resistance and pressure resistance. The thickness of the insulating plate 13 is, for example, about 2 mm, and a circular opening 13 a having a diameter of about 5 mm is provided in the central portion of the insulating plate 13. A screw groove is formed on the inner wall surface of the opening 13a, and the insulating plate 13 can be attached to the pressurizing part 12 by screwing the convex part 12b into the opening 13a.

  As shown in FIG. 1, the electrode 2 is formed by screwing the convex portion of the pressurizing portion 12 to which the insulating plate 13 is attached into the concave portion 11 b of the main body portion 11. Therefore, a narrowed portion 14 is formed at the distal end portion of the electrode 2 so as to restrict a current-carrying region of the current passing through the main body portion 11 by interposing the insulating plate 13 between the main body portion 11 and the pressure portion 12. The nugget diameter L1 at W can be made smaller than the electrode diameter L2. In addition, it is preferable that the material of the electrode 3 facing the electrode 2 with the outer plates 4 and 5 interposed therebetween is chrome copper like the main body portion 11 of the electrode 2.

  When welding the outer plates 4 and 5 using the spot welding apparatus 1 having the above configuration, first, the stacked outer plates 4 and 5 are held with a jig or the like. As shown in FIG. 1, the welded portion W is formed by sandwiching the welding portion between the electrodes 2 and 3 and energizing while applying a constant pressure to the outer plates 4 and 5.

  Here, in the case of using the conventional spot welding apparatus, as shown in FIG. 3A, the electrodes 21 and 22 bite into the outer plates 4 and 5 due to the applied pressure, and the surface of the outer plates 4 and 5 is welded. As a result, the indentation of the welded portion V is easily noticeable. In order to solve this problem, as shown in FIG. 3B, one electrode may be a copper plate electrode 23 to reduce the biting of the electrodes 21 and 23 into the outer plates 4 and 5.

  However, when the base material is a thin plate like the outer plates 4 and 5, although the indentation of the welded portion V itself is small, there is a fear that the entire base material may be distorted by rising around the welded portion V and causing deformation. In this case, the base material may be convex with the welded portion V as the center, and the indentation may be noticeable instead.

  On the other hand, when the spot welding apparatus 1 is used, since the above-described throttle portion 14 is provided on the electrode 2, the current-carrying region is narrowed by the throttle portion 14, and the nugget diameter L1 of the weld portion W is , Smaller than the electrode diameter L2. The size of the nugget diameter L1 can be generally controlled by the diameter of the opening 13a of the insulating plate 13 and the thickness of the pressure unit 12. In the present embodiment, the nugget diameter L1 is about 6 mm to 7 mm with respect to the electrode diameter L2 of about 30 mm.

  Then, by making the nugget diameter L1 of the welded portion W smaller than the electrode diameter L2, in the spot welding apparatus 1, a sufficient area around the welded portion W including the welded portion W is added by the pressurizing unit 12 during energization. The weld W can be formed while pressing. Therefore, when the welding part W is formed using this spot welding apparatus 1, the amount of indentation in the welding part W and the deformation of the outer plates 4 and 5 around the welding part W can be suppressed at the same time. In the stainless steel vehicle using the joined body of the outer plates 4 and 5, the impression and distortion are not noticeable, and the appearance is good.

  For example, the smoothness of the indentation of the welded portion W when using a conventional spot welding apparatus as shown in FIG. 3B is about 0.02 mm to 0.05 mm. On the other hand, the smoothness of the indentation of the welded portion W when the spot welding apparatus 1 is used is about 0.005 mm, and the smoothness can be improved by about one digit.

  Moreover, in the spot welding apparatus 1, since the pressurization part 12 is formed with the chrome copper of the same material as the main-body part 11 of the electrode 2, the cooling function around the welding part W by the pressurization part 12 is fully ensured, A healthy nugget can be formed. Furthermore, since the aperture 14 is formed by the insulating plate 13 having the aperture 13a having a diameter smaller than the electrode diameter L2, the aperture 14 can be more reliably formed by the aperture 13a.

  In addition, the body portion 11 of the electrode 2 is provided with a concave portion 11b having substantially the same diameter as the opening portion 13a of the insulating plate 13, while the pressurizing portion 12 is provided with a convex portion 12b corresponding to the concave portion 11b. The electrode 2 is formed by screwing the convex portion 12 b of the pressurizing portion 12 through which the opening portion 13 a of the insulating plate 13 is passed into the concave portion 11 b of the main body portion 11 of the electrode 2. Thereby, the electrode 2 which has the aperture | diaphragm | squeeze part 14 and the pressurization part 12 can be comprised easily. Moreover, since the insulating plate 13 and the pressurization part 12 are detachable with respect to the main-body part 11 of the electrode 2, it becomes possible to replace the insulation plate 13 and the pressurization part 12 as needed.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the diameter of the opening 13a of the insulating plate 13 and the thickness of the pressure unit 12 are set so that the nugget diameter L1 is about 6 mm to 7 mm with respect to the electrode diameter L2 of about 30 mm. However, the ratio of the nugget diameter L1 to the electrode diameter L2 can be appropriately set according to the thickness of the outer plates 4 and 5, for example. In addition to the above-described chromium copper, alumina-dispersed copper, silver tungsten, beryllium alloy, or the like can be used as the material for the electrodes 2 and 3.

  DESCRIPTION OF SYMBOLS 1 ... Spot welding apparatus, 2, 3 ... Electrode, 4, 5 ... Outer plate (thin steel plate), 11 ... Main body part, 11b ... Recessed part, 12 ... Pressurizing part, 12b ... Convex part, 13 ... Insulating plate, 13a ... Opening part, 14 ... throttle part, L1 ... nugget diameter, L2 ... electrode diameter, W ... welded part.

Claims (3)

It is a spot welding apparatus that sandwiches a laminated steel sheet with a pair of electrodes and forms a weld by energizing the sheet steel with the electrode while applying pressure,
The electrode includes a narrowed portion that reduces a current-carrying region to a nugget diameter smaller than the electrode diameter, and passes the current narrowed by the narrowed portion toward the thin steel plate and the welded portion. And a pressurizing part that pressurizes around the welded part,
The narrowed portion is formed by an insulating plate provided with an opening having a smaller diameter than the electrode diameter,
The body portion of the electrode is provided with a recess having substantially the same diameter as the opening of the insulating plate, while the pressurizing portion is provided with a protrusion corresponding to the recess,
The electrode is formed by engaging the convex portion of the pressurizing portion through which the opening of the insulating plate is passed with the concave portion of the main body portion of the electrode .   The spot welding apparatus according to claim 1, wherein the pressurizing portion is made of the same material as the main body portion of the electrode. Wherein the insulating plate is spot welding apparatus according to claim 1 or 2, characterized in that phenol resin.

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