JP5111093B2 - Parallel gap welding equipment - Google Patents

Description

  The present invention relates to a joining apparatus, and more particularly to a structure of a holding portion of a welding electrode in a parallel gap welding apparatus.

  Conventionally, for the purpose of connecting lead wires and wires to electrodes and the purpose of connecting a metal ribbon material to repair the wiring pattern of a printed wiring board in which disconnection has occurred, the pressing force can be relatively small. Parallel gap welding, which is an advantageous resistance welding method for welding a small area, is used. As an example of the welding work by this method, the state of welding in disconnection repair of a printed wiring board will be described with reference to FIG.

  In FIG. 7, 51 is a printed wiring board, 52 is a wiring pattern formed on the printed wiring board 51, 54 is a ribbon material which is a metal repair member, and 55 is an electrode assembly. Here, the printed wiring board 51 is placed on the stage 53 so as not to be displaced, and the stage 53 is placed in the X direction on the horizontal plane so that the welded part in the vicinity of the disconnection part 52A is located immediately below the electrode assembly 55. , Move in the Y direction to perform the positioning operation. Further, it rotates in the θ direction in order to set the posture on the horizontal plane to a predetermined angle.

After the positioning, the ribbon material 54 is applied to the disconnection location 52A, and the wiring pattern 52 and the ribbon material 54 on both sides of the disconnection location 52A are welded at positions 54A and 54B shown in FIG. In the electrode assembly 55, as shown in FIG. 7B, a pair of electrodes 55A and 55B are arranged with a gap 55C in between, and after pressing the ribbon material 54, which is a member to be joined, at the tips of both electrodes, A potential difference is applied to both electrodes by the power supply means that does not, and a current flows through the wiring pattern 52 and the ribbon material 54 due to this potential difference, and a nugget is formed by the Joule heat generated in this portion and welding is performed.

  Since it is such a welding method, it is not necessary to hold | pinch both the side surfaces of the overlapped to-be-joined member with a pair of electrodes like the spot welding method. Therefore, it can be said that the parallel gap welding method is a very advantageous welding method for the above-described disconnection repair on the printed wiring board and the connection of the lead wire to the electrode already formed on the electrical component. However, in this parallel gap welding method, the size of the gap between the pair of electrodes (hereinafter referred to as gap length) occupies a large specific gravity as a control factor for welding. In order to control the gap, there is a description that defines the setting range of the gap length.

  Here, when the control factor of this parallel gap welding method is compared with the spot welding method, in the case of the spot welding method, the load applied to the welding object by the electrode, the welding current, and the energization time are control factors. In parallel gap welding, in addition to these, the gap length and the equal contact resistance of both electrodes are said to affect the welding results. There are several types of such electrode holding methods of the parallel gap welding method, and as a commonly used configuration, an integrated type electrode 56 as shown in FIG. There is a form to use.

  The integral type electrode 56 is obtained by integrally fixing a pair of electrodes with an electrically insulating adhesive, and fixing this to the lower end of the pressurizing means 57. The pressurizing means 57 is for abutting the electrode with a predetermined load against the object to be welded, and is used by polishing the tip of the fixed electrode 56 horizontally. At this time, since the electrodes 56 are integrated, when the surface of the welding target is not a perfect plane, a difference occurs in the load on the welding target of both electrodes, and an equal contact resistance between the electrodes cannot be obtained. Needless to say, it is impossible to adjust the gap length.

  In addition, there is a form in which a split type electrode 58 as shown in FIG. 8B is used by being set on the pressurizing means 59, and in this case, a pair of pressurization provided independently at the lower end of the pressurizing means 59. One of the electrodes 58 is fixed to each of the shafts 59A and 59B. Even if the vertical positions of the lower ends of both electrodes are not aligned or the surface of the welding object is not a perfect plane, both electrodes follow this independently by the pressure shafts 59A and 59B, and the welding object There is no difference in load with respect to. However, the setting of the gap length can be adjusted only when the electrode 58 is fixed to the pressure shafts 59A and 59B, and is not variable.

As yet another embodiment, a parallel gap welding apparatus described in Patent Document 2 will be described with reference to FIG. In FIG. 9, (a) is a side view showing an electrode holding part of a conventional parallel gap welding apparatus. Further, (b) is a sectional view showing a section AA shown in (a). In (b), the cross section is only the pressure shaft 61. Next, (c) is a sectional view showing a section BB shown in (a).

  First, in FIG. 9A, reference numeral 62 denotes an elevating unit that performs an elevating operation that approaches or separates a predetermined amount toward the welding target. Further, the pressure holding shaft 61 protruding downward from the bottom surface of the elevating part 62 has an electrode holding part 63 fixed in the vicinity of its tip, and a split type electrode 64 is held by the electrode holding part 63. Here, the pressure shaft 61 protrudes downward with respect to the elevating part 62 so as to be movable up and down, and after the elevating part 62 descends and the tip of the electrode 64 contacts the object to be welded, the tip of the electrode 64 is subjected to a predetermined load. Is held by the elevating part 62 so as to press the object to be welded.

  Further, as shown in FIG. 9B, the electrode holding portion 63 is divided into two blocks 63A and 63B for holding one 64A and the other 64B of the pair of electrodes 64, respectively. Further, each of the angle adjusting blocks 65A, 65B, Calibration is performed by electrode holding blocks 66A and 66B and leaf springs 67A, 67B, 67A 'and 67B'. The angle adjustment block 65A is assembled integrally with the electrode holding block 66A via the leaf springs 67A and 67A ', and the angle adjustment block 65B is also assembled integrally with the electrode holding block 66B via the leaf springs 67B and 67B'. Yes. The electrode holding blocks 66A and 66B have split-type electrodes 64A and 64B fixed thereto by electrode holders 68A and 68B. Here, a gap 69 is provided between the electrodes 64A and 64B, and a gap is also provided between the blocks 63A and 63B.

FIG. 9C is a cross-sectional view showing how the blocks 63 </ b> A and 63 </ b> B are fixed to the pressure shaft 61. The surface near the lower end of the pressure shaft 61 is electrically insulated, and a cylindrical nut 70 is fitted therein. Two screws 71A and 71B are threadedly engaged with the cylindrical nut 70 from the horizontal direction, and the pressure shaft 61 is clamped and fixed between the blocks 63A and 63B. Here, since the two screws 71A and 71B are insulated from the blocks 63A and 63B by the insulating washers 72A and 72B, there is no electrical continuity between the blocks 63A and 63B.

  Further, by turning the knob 80, the screw 73 pivotally attached to the knob 80 is rotated, and the interval between the angle adjusting block 65A and the angle adjusting block 65B on the knob 80 side changes. Here, the insulating washers 74 and 75 and the insulating cylinder 76 maintain the electrical insulation between the angle adjusting blocks 65A and 65B. The compression coil spring 77 generates a force in a direction to separate the angle adjustment blocks 65A and 65B when the interval between the electrodes 64 is widened, and removes backlash generated in the screwed portion of the screw 73. With such a structure, turning the knob 80 causes relative angle changes around the pressure shaft 61 in the angle adjustment blocks 65A and 65B, and the gap lengths of the electrodes 64A and 64B also change.

  Further, two leaf springs 67A and 67A 'and 67B and 67B' arranged in parallel in the pressing direction hold the electrodes 64A and 64B elastically in the pressing direction, respectively. Even when the positions of the tips of the fixed electrodes 64A and 64B in the vertical direction are not completely aligned, or when the upper surface of the object to be welded is not flat, both electrodes come into contact with the object to be welded with an equal load. It is to follow. Further, 67A ′ with respect to the leaf spring 67A and 67B ′ with respect to the 67B are arranged in parallel, so that when the deformation of the leaf spring is in a minute range, the tip of the electrode 64 is in the direction of pressing the pressure shaft 61. Move in parallel direction.

In addition, the angle adjusting blocks 65A and 65B and the electrode holding blocks 66A and 66B including the four leaf springs use a highly conductive material as a material, and are provided at the right end as viewed in FIGS. 9A and 9B. It is possible to connect a feeding cable (not shown) to the connecting terminals 78A and 78B, and supply the welding current to the tip of the electrode 64. Therefore, by providing such an electrode holding structure, each of the pair of electrodes independently has elasticity in the vertical direction, and the gap length can be easily adjusted for each kind of welding target or each welding condition. is there.

Japanese Patent No. 28877883 (2nd page, FIG. 1) Japanese Examined Patent Publication No. 42-24972 (first page, FIG. 1)

  However, in the electrode holding structure described with reference to FIG. 9, the axis of the pressure shaft 61 that applies the pressing force to the welding target to the electrode holding part and the position of the tip of the electrode 64 that directly presses the welding target are offset. Yes. Therefore, for example, the following problem arises in order to cope with the miniaturization of a welding target represented by recent repair of a high-definition wiring pattern. FIG. 10A is a side view of the gap length variable electrode holding portion described with reference to FIG. Here, when a pressing force is applied to the electrode holding portion 63 from the pressure shaft 61 in the direction of arrow (A), the tip of the electrode 64 in contact with the object to be welded receives a reaction force in the direction of arrow (A).

  Then, since there is an offset between the vector (A) and the vector (A), a moment force is generated from the portion supporting the pressure shaft 61 inside the elevating part 62 to the tip of the electrode 64, and even if the rigid part is Even if the structure is firmly fixed, the tip of the electrode 64 is displaced in the direction of the arrow (c) by this action. Here, the electrode 64 is obliquely fixed to the electrode holding blocks 66A and 66B so that the joint portion can be observed from directly above with a microscope (not shown) provided separately. As shown in FIG. Even if 64 is fixed vertically, the offset still exists and the tip of the electrode 64 is displaced in the direction of the arrow (c).

  Therefore, for example, the pattern width of the above-described high-definition wiring pattern is not rarely several tens of μm in recent years. If the width of the ribbon material for welding and repairing at the broken portion is equal, the arrow ( Even if the displacement of the tip of the electrode 64 in the direction of c) is small, it greatly affects the welding quality. And it is extremely difficult to cope with such a problem of such a slight deviation in the arrow (c) direction by increasing the rigidity while maintaining the form of the conventional electrode holding portion.

  Also, as shown in FIGS. 9B and 9C, when the knob 80 is turned to adjust the gap length, the blocks 63A and 63B have a relative angle between them in the rotational direction around the pressure shaft 61. Therefore, the angle of the pair of contact surfaces with the welding target of the electrode 64 also changes relatively. For this reason, for example, the following phenomenon can be considered when the ribbon material is welded and repaired at the disconnection portion of the wiring pattern. Assuming that the gap length is reduced, the state of the contact surfaces 79 and 79 indicated by the oblique lines in FIG. 11A is inclined as shown in FIG. 11B by reducing the gap length. Change. As a property of the parallel gap welding method, since the current flowing through the welding target is biased to the closest part of the contact surfaces of both electrodes, the current i is biased toward one side of the welding target (ribbon material and wiring pattern in this case). This causes a problem that the position of the nugget also deviates from the desired position.

The present invention provides, as a first aspect, a parallel gap welding apparatus that uses a pair of electrodes attached to a single pressure shaft, and the mechanism that holds each of the pair of electrodes includes the pressure shaft. A first pair of leaf springs provided in parallel with a gap in a direction orthogonal to the pressing direction of the first and a second pair of leaf springs provided in parallel with a gap in the pressing direction of the pressure shaft A connecting portion that connects one end of the first pair of leaf springs and one end of the second pair of leaf springs, and the pressure shaft provided at the other end of the first pair of leaf springs And an electrode fixing portion provided at the other end of the second pair of leaf springs, and an interval adjusting portion for adjusting an interval between the two connecting portions corresponding to each of the pair of electrodes And a pair of electrodes are mounted on the electrode fixing portion. When digits, parallel, wherein a virtual straight line connecting the center of the contact surface to be welded of the pair of electrodes, disposing the electrode fixing unit so as to be positioned on the extension of the axis of the pressure shaft A gap welding apparatus is provided.

Further, as a second aspect of the present invention, the interval adjusting portion expands or contracts the interval between the two connecting portions by rotation of a screw that passes through one connecting portion and is screwed to the other connecting portion. The parallel gap welding apparatus according to the first aspect is provided in which the two first pair of leaf springs are deformed according to the above.

Furthermore, as a third aspect of the present invention, the gap adjusting portion is disposed in a gap between the second pair of leaf springs. The parallel gap according to any one of the first and second aspects, A welding apparatus is provided.

  According to the first aspect of the present invention, even when the vertical positions of the electrode tips are not completely aligned, or even when the surface of the welding target is not a perfect plane, the pair of electrodes can be welded with an equal load. The surface to be welded is elastically pressed independently so as to press. In addition to the structure that can easily adjust the distance between the pair of electrodes, the structure eliminates the offset between the tip of the electrode and the axis of the pressure shaft. No force other than that in the pressurizing direction is generated. Therefore, even if the electrode presses the object to be welded with a predetermined load, the positional deviation of the contact portion of the electrode tip does not occur.

  According to the second aspect of the present invention, the first pair of leaf springs interposed between the attaching portion to the pressure shaft and the connecting portion are deformed, so that the two connecting portions are rotated by the rotation of the screw. It moves parallel to each other to expand or contract the interval. Accordingly, the tip of the electrode fixed to the connecting portion via the second pair of leaf springs and the electrode fixing portion, that is, the contact portion with the welding target also moves in parallel with each other, and the pair of contact portions Even if the interval is enlarged or reduced, the change in the mutual posture as shown in FIG. 11B does not occur.

  Furthermore, according to the third aspect of the present invention, since the mechanism for expanding and reducing the distance between the two connecting portions is formed using the space between the second pair of leaf springs, the electrode holding mechanism can be reduced in size. Therefore, a parallel gap welding apparatus suitable for fine welding objects can be configured.

  Next, an embodiment of a parallel gap welding apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a front view showing an embodiment of a parallel gap welding apparatus according to the present invention, and FIG. 2 is a side view thereof. 1 and 2, reference numeral 1 denotes an elevating part, 2 denotes a pressure shaft, 3 denotes an electrode holding mechanism, and 4 denotes an electrode. The electrode 4 is the same as that described in the prior art, and is fixed to the electrode holding mechanism 3 with a gap between the pair of electrodes 4A and 4B. Welding is performed by passing an electric current through the welding object in contact. In the present embodiment, a power supply cable (not shown) is connected to connection terminals 5A and 5B provided on the upper part of the electrode holding mechanism 3, and power is supplied from a power supply (not shown). As this power source, a pulse heat power source is used that instantly raises the voltage and follows up with a quick response according to a profile input in advance.

  Moreover, the raising / lowering part 1 performs the operation | movement of approach and separation | spacing with respect to the welding object. In reality, in the case of all welding apparatuses, the movement is not necessarily up and down. However, in this document, on the assumption that the movement is close to and away from the welding target placed on a stage (not shown), that is, up and down movement, It describes. And when this raising / lowering part 1 descend | falls predetermined distance and the contact surface of the electrode 4 contact | abuts to welding object, after that, the pressurization shaft 2 will sink toward the inside of the raising / lowering part 1 by the reaction force. Here, the pressurizing shaft 2 is elastically urged toward the welding target in the elevating unit 1, and the urging stress increases in accordance with the amount of sinking into the elevating unit 1. When the biasing stress matches the preset stress, the welding current from the power source is supplied to the electrode 4.

  In FIG. 1, reference numeral (d) indicates the axial center of the pressure shaft 2. The downward extension line passes through the gap between the pair of electrodes 4A and 4B and is positioned between the contact surfaces of both electrodes. Also in FIG. 2, the axis of the pressurizing shaft 2 is indicated by a symbol (D), and the downward extension line is located at the center of the contact surface of the electrode 4. Although the side surface of the electrode 4B is shown in FIG. 2, the extension line of the axis (d) is set so as to coincide with a straight line connecting the centers of the contact surfaces of the pair of electrodes.

  Next, details of the electrode holding mechanism 3 shown in FIG. 1 will be described with reference to FIGS. 3 is a front view of the electrode holding mechanism 3, and FIG. 4 is a side view thereof. In FIG. 3, reference numerals 6 </ b> A and 6 </ b> A ′ denote a first pair of leaf springs provided to hold one electrode 4 </ b> A of the electrode 4, with a gap in a direction perpendicular to the pressing direction of the pressure shaft 2. And provided in parallel. Reference numerals 6B and 6B ′ denote a first pair of leaf springs provided to hold the other electrode 4B of the electrode 4, and are parallel to each other with a gap perpendicular to the pressing direction of the pressing shaft 2. Is provided.

  The upper ends of the first pair of leaf springs 6A and 6A 'are connected to the attachment portion 7A, and the upper ends of the first pair of leaf springs 6B and 6B' are connected to the attachment portion 7B. These attachment portions 7A and 7B are fixed by two screws 8 and 9 so as to sandwich the vicinity 2A of the lower end of the pressure shaft 2 whose surface is electrically insulated. The front and rear positions of the screws 8 and 9 are shown in FIG. The electrode holding mechanism 3 holding the electrode 4 by this fixing is connected to the pressure shaft 2 and performs a welding operation.

  In FIG. 3, reference numerals 10 </ b> A and 10 </ b> A ′ denote a second pair of leaf springs provided to hold one electrode 4 </ b> A of the electrode 4, and are provided in parallel with a gap in the pressing direction of the pressure shaft 2. ing. Reference numerals 10B and 10B 'denote a second pair of leaf springs provided to hold the other electrode 4B of the electrode 4, and are provided in parallel with a gap in the pressing direction of the pressure shaft 2. . As shown in FIG. 4, the second pair of leaf springs 10B and 10B 'has one end on the back side screwed to the connecting portion 11B by a screw 12, and one end on the front side is an electrode fixing portion 13B. Are screwed to each other by screws 12.

Although not shown in FIG. 4, the second pair of leaf springs 10A and 10A 'also has one end on the back side screwed to the connecting portion 11A and one end on the front side screwed to the electrode fixing portion 13A. It is worn. As shown in FIG. 4, the lower ends of the first pair of leaf springs 6B and 6B 'described above are connected to the connecting portion 11B, which is not shown, but the first pair of leaf springs. 6A and 6A 'are also connected to the connecting portion 11A. The structural relationship between the two first pairs of leaf springs 6A, 6A ', 6B, 6B' and the mounting portions 7A, 7B and the connecting portions 11A, 11B is a view of the cross section of the electrode holding mechanism 3 as seen from the front. This is clearly shown in FIG.

  Further, as shown in FIG. 3, a pair of electrodes 4A and 4B are fixed to the electrode fixing portions 13A and 13B by electrode pressers 14A and 14B. The electrode fixing portions 13A and 13B are provided with positioning grooves, and the electrodes 4A and 4B are fixed so as to be sandwiched between the electrode pressers 14A and 14B while being fitted in the grooves. However, the positions of the electrodes 4A and 4B can be adjusted by loosening the fixing screws of the electrode holders 14A and 14B. In the present embodiment, the first pair of leaf springs 6A, 6A ′, 6B, 6B ′ are integrally formed with the mounting portions 7A, 7B and the connecting portions 11A, 11B by cutting, and the second pair of plates. The springs 10A, 10A ', 10B, and 10B' are screwed at both ends to the connecting portions 11A and 11B and the electrode fixing portions 13A and 13B, but this connection structure may be any method or the action of the springs. Other methods such as welding may be used as long as they are not freely connected in the direction.

  Next, a structure for adjusting the distance between the pair of electrodes 4A and 4B will be described with reference to FIG. FIG. 5 shows the electrode holding mechanism 3 as viewed from the front. The electrode 4, the electrode retainers 14 </ b> A and 14 </ b> B, and the electrode fixing portions 13 </ b> A and 13 </ b> B are not shown, and the second pair of leaf springs 10 </ b> A, 10 </ b> A ′, 10 </ b> B, 10B ′ and a cross section of the connecting portions 11A and 11B. In the structure of the present embodiment, the distance (e) between the connecting portions 11A and 11B is changed by turning the knob 15. The structure of the screw connected to the knob 15 and its surroundings, that is, the structure of the interval adjusting portion is the same as the structure described with reference to FIG. 9C in the prior art. Omitted. However, in this embodiment, the same structure as that described with reference to FIG. 9C is adopted, but the first pair of leaf springs 6A, 6A ′, 6B, 6B ′ has a repulsive force against deformation. Therefore, the compression coil spring for obtaining the force in the direction of separating the connecting portions 11A and 11B and the force for removing the backlash may be excluded from the components.

  Here, when the interval (e) is changed by turning the knob 15, the first pair of leaf springs 6A, 6A ', 6B, 6B' is deformed into a substantially S-shape. However, since the pair of leaf springs 6A and 6A ', 6B and 6B' are provided in parallel to the direction orthogonal to the pressing direction of the pressing shaft 2, the connecting portions 11A and 11B connected to their lower ends are provided. Is also translated in a direction orthogonal to the pressing direction of the pressure shaft 2 (approximately when the movement distance is small). Accordingly, the second pair of leaf springs 10A, 10A ', 10B, 10B' (see FIG. 4) screwed to the connecting portions 11A, 11B on the back side of the connecting portions 11A, 11B also move in parallel in the same direction. The electrode fixing portions 13A and 13B and the pair of electrodes 4A and 4B screwed on the side also translate in a direction perpendicular to the pressing direction of the pressure shaft 2.

  Next, a structure in which the pair of electrodes 4A and 4B independently follow the unevenness of the surface to be welded will be described with reference to FIG. FIG. 6 is a side view of the electrode holding mechanism 3, and the surface of the electrode 4B that is in contact with the other electrode 4B is higher than the surface of the electrode 4A that is in contact with the electrode 4A. It is drawn assuming the case. Actually, this height (f) is assumed to be a minute height in units of μm, but in FIG. 6, the distance is exaggerated. In addition, the second pair of leaf springs 10A and 10A ′ supporting one electrode 4A is depicted as not deformed.

  Here, if unevenness exists on the surface of the welding object, the second pair of leaf springs 10A, 10A ', 10B, 10B' is independently deformed into a substantially S shape, and the pair of electrodes 4A is elastically deformed. 4B is loaded. Since the pair of leaf springs 10A and 10A ', 10B and 10B' are provided in parallel with the pressing direction of the pressure shaft 2, the pair of electrodes 4A and 4B supported by them are also provided on the pressure shaft 2. The welding object is pressed without changing the posture with respect to the pressing direction. Further, in this explanation, the case where unevenness exists in the welding target has been described, but the same effect is also obtained when there is no unevenness in the welding target and the vertical positions of both electrode tips are not aligned. Needless to say to play.

  As described above, by using the parallel gap welding apparatus of the present embodiment, there is no offset between the extension line of the axial center of the pressure shaft 2 and the position of the contact surface of the electrode 4 on the welding target (see FIG. 2). In addition, since the first pair of leaf springs are arranged in parallel with a gap in the direction orthogonal to the pressing direction of the pressure shaft 2, the two contact surfaces of the electrode 4 have their postures (in the horizontal plane). Increase or decrease the interval without changing the angle. In addition, since the electrode interval adjusting portion is disposed in the gap between the second pair of leaf springs, the electrode holding mechanism can be reduced in size.

Front view showing an embodiment of the present invention Side view showing an embodiment of the present invention The principal part detail front view which shows embodiment of this invention The principal part detailed side view which shows embodiment of this invention FIG. 2 is a detailed cross-sectional view showing a main part of the embodiment of the present invention. The principal part detailed side view which shows embodiment of this invention Perspective view and side view showing conventional technology Side view showing conventional technology Side view and sectional view showing conventional technology Side view showing conventional technology Plan view showing conventional technology

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lifting part 2 Pressure shaft 3 Electrode holding mechanism 4 Electrode 5A, 5B Connection terminal 6A, 6A ', 6B, 6B' 1st pair of leaf | plate springs 7A, 7B Attachment part 8, 9, 12 Screw 10A, 10A ', 10B, 10B 'Second pair of leaf springs 11A, 11B Connecting portion 13A, 13B Electrode fixing portion 14A, 14B Electrode retainer 15 Knob

Claims (3)

A parallel gap welding apparatus that uses a pair of electrodes attached to a single pressure shaft, wherein the mechanism for holding each of the pair of electrodes has a gap in a direction perpendicular to the pressing direction of the pressure shaft. A first pair of leaf springs provided in parallel with each other, a second pair of leaf springs provided in parallel with a gap in the pressing direction of the pressure shaft, and the first pair of plates A connecting portion that connects one end of the spring and one end of the second pair of leaf springs, an attachment portion to the pressure shaft provided at the other end of the first pair of leaf springs, and the second An electrode fixing portion provided at the other end of the pair of leaf springs, and an interval adjusting portion for adjusting an interval between the two connecting portions corresponding to each of the pair of electrodes. When a pair of electrodes is attached, Virtual straight line connecting the centers of the contact surface to the subject, a parallel gap welding apparatus characterized by disposing the electrode fixing unit so as to be positioned on the extension of the axis of the pressure shaft. The interval adjusting portion expands or contracts the interval between the two connecting portions by rotation of a screw that passes through one connecting portion and is screwed into the other connecting portion. 2. The parallel gap welding apparatus according to claim 1, wherein the plate spring is deformed. 3. The parallel gap welding apparatus according to claim 1, wherein the interval adjusting portion is disposed in a gap between the second pair of leaf springs.

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