SPOT GUN FOR A WELDER MACHINE

Abstract: A bearing is located at the front of a frame (1) and through use of this bearing (4) an electrode (6A) on one side and an electrode (6B) on another side can be positioned opposing each other on the horizontal axis central line, so that with the electrode part (2) on one side having an electrode (6A) bit at the front being movable forwards and backwards while connected with the bearing (4), an object to be welded can be gripped between the electrode (6A) bit on one side and the electrode (6B) bit on the other side; if the electrode on the other side which is provided with a bracket (8) having the other electrode bit at its tip, and which is attached externally to the bearing (4), is rotated around the electrode on one side, spot welding in many different positions, including upwards, downwards and sideways, can be easily achieved.

Description: This invention concerns a spot gun for a welder machine, and more specifically a hand-held spot gun used in connection with a variety of spot welding operations, which is manually operable. Description of Prior Art Hand-held spot guns constructed in accordance with the prior art (see Fig. 9) have had a pair of upper and lower protruding brackets 8 extending parallel with respect to each other at the front of the gun body 23, with a pair of electrode bits 6A, 6B attached in an opposing relationship at the end of each bracket 8. In addition these guns are constructed such that a throttle lever 11 is mounted at the back of the gun body 23 and a grip lever 12 is mounted at the side of the gun body 23, and the gun body 23 is connected to the ends of two cables 13 extending from the main welder machine (not shown); 5A and 5B are cable connectors. The device is employed by gripping the grip lever 12 in one hand to hold the main body and operating the throttle lever 11 with the other hand, thus moving the end of the upper bracket 8 so that the pair of electrode bits 6A, 6B are moved together to grip the object to be welded (not shown) between the electrode bits 6A, 6B and allowing electric current to flow to carry out spot welding. When hand-held spot welding guns of this prior art type were employed in welding of window frames where forward welding, backward welding or sideways welding was required, the whole spot gun had to be moved continually either forwards or backwards while connected to the thick cables 13. This was because the gun was constructed with the pair of upper and lower brackets 8 protruding at the front of the gun body 23, with the brackets 8 and the electrode bits 6A, 6B fixed in position. This type of welding in which the position of the gun had to be continually moved backwards and forwards or sideways when welding objects, such as window frames, gripped between a pair of upper and lower opposed electrode bits 6A, 6B, was extremely difficult, and hand-held welding work of this kind was performed inefficiently and with reduced ease of operation. FR-A-2 123 894 describes a spot welding apparatus for welding an overhanging horizontal flange comprising an upper electrode that can be moved downwardly along an axis and a lower electrode that can be moved upwardly along the same axis to clamp between them the flange to be welded. The two electrodes extend above the flange being welded and the lower electrode is mounted on a crook so that it can be brought up underneath the flange while the upper electrode engages the top of the flange. JP-60-96377 describes a welding apparatus having two opposed electrodes one of which is in the form of a crook so that it can extend on one side the object being welded while the other electrode is located on the opposed side of the object. Summary of the Invention This invention aims to provide a new type of spot welding gun which eliminates the above disadvantages of the prior art; the welding gun is defined in the accompanying claims. Brief Description of the Drawings The present invention will be described in further detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is an abbreviated sectional side view of one embodiment of the spot gun of this invention. Figure 2 is a plan view of the spot gun viewed along the line of arrow II in Figure 1. Figure 3 is a sectional side view taken along the lines III-III in the embodiment of Figure 1. Figure 4 is a sectional side view across the direction IV-IV in Figure 1. Figure 5 is a side view of a spot gun in accordance with a second embodiment of this invention. Figure 6 is an abbreviated sectional side view of the rotary position lock in accordance with another embodiment of this invention. Figure 7 is a side view along the lines VII-VII in Figure 6. Figure 8 is an abbreviated side view of a spot gun of a third embodiment of this invention. Fig. 9 is a side view of a spot gun constructed in accordance with the prior art. Description of the Preferred Embodiments Some example embodiments of this invention will now be described in detail. For the purposes of this discussion, where the words "upper and lower", "forwards and backwards", and "vertical and horizontal" are used to indicate direction, the direction indicated should be interpreted on the basis of the embodiment shown in Fig. 1. First, the first embodiment of this invention as indicated in Figs. 1 through 4 will be described. This spot welding gun has a frame 1 with a bearing 4 at the front (left hand side in Fig. 1) serving as a holder, with the frame being provided with a cable connector 5A below the bearing 4; a first electrode 2 with a projecting electrode bit 6A at the front thereof mounted retractably (retracting in the left/right direction in Fig. 1) on the bearing 4 of the frame 1, and with another cable connector 5B on the lower bottom edge thereof; and a second electrode 3 on the other side of the welding gap with an overhanging bracket 8 protruding from the top edge of a rotary base 7, with an opposing electrode bit 6B attached at its tip. The horizontal central axis 2X of electrode bit 6A of electrode 2 on one side of the welding gap and electrode bit 6B of the electrode 3 on the other side of the welding gap are aligned so as to oppose each other. At the rear (right hand side in Figure 1) of the frame 1 and at the rear of the first electrode 2 on one side of the welding gap, there is constructed a handle 9 which, in effect, includes a grip lever 11; the electrode 2 is movable backwards and forwards by the operation of a throttle lever 10, which is connected to the back of the electrode 2 and pivotally mounted with respect to grip lever 11. The spot gun is constructed such that if the spot gun is held in one hand by a grip handle 12 (see Figures 2 and 3) which projects from the side of frame 1, while at the same time the throttle lever 10 is operated with the other hand, the electrode bit 6A advances along the horizontal central axis 2X so as to permit the object to be welded to be gripped between electrode bits 6A and 6B, whereupon electricity is conducted through cables 13 to electrode bits 6A, 6B to permit spot welding. Describing the operation in more detail, the frame 1 is constructed to have an overall bow shape and is provided with the bearing 4 at the forward lower end which surrounds the horizontal central axis 2X, and the handle 9 for the grip lever 11 at the rear end thereof. The first electrode 2 is mounted retractably in the bearing 4 by means of an insulated part 14, and its electrode bit 6A projects forwardly, while to the rear the lever 10 is connected to the electrode 2 by means of another insulated part 14. This lever 10 is joined to the handle 9 by a link construction comprising multiple arms. The other electrode 3 has the base 7 mounted upon the bearing 4 so that it can rotate about axis 2X, and is also provided with the bracket 8 having an overhanging shape which hangs down vertically from the upper edge of the base 7 in front of the electrode 2. The other electrode bit 6B is mounted at the front lower part of the bracket 8. Bracket 8 can be rotated to any optional angle around the electrode bit 6A. Furthermore, the latter electrode 3 is provided with a rotary position lock 15, so that by rotating the electrode 3 to any one of a number of optional positions indicated by dotted lines 3A-3D in Figure 3, the rotary position can be set with one touch. In the example shown in Figure 3, there are sixteen optional positions. The rotary position lock 15 of this embodiment (see Figure 4) is constructed of a combination of a set of locking holes 16 defined upon the base 7 and arrayed concentrically with the bearing 4 and locking balls 17 spring-biassed outwardly from the frame part 1. When the base 7 is rotated by hand, the locking balls 17 fit into the locking holes 16, so that the rotation can be stopped at any desired rotary position 3A-3D. A "locking pin" may be substituted for each locking ball 17. In the drawing, 18 is a return spring which forces the electrode 2 to retract, while 19 is a bellows cover which covers the rear end of the electrode 2. Next, the spot gun of the second embodiment of this invention will be described with reference to Fig. 5. In the drawing, the spot gun of this embodiment is also constructed so as to comprise a frame 1, almost identical to that of the embodiment described in connection with Fig. 1, and an electrode 2 on one side of the welding gap and another electrode 3 on the other side of the welding gap. Electrode 3 is provided with a rotary position lock which can be stopped as required at any desired rotational position. The spot gun in Fig. 5 is constructed such that electrode 3 is formed with the electrode bit 6B disposed upon the lower end of a rod which projects downwardly from the left end of the bracket 8 which projects from the end of the base 7, so that the inner part of electrode bit 6B and the other electrode bit 6A are opposed with respect to each other. Electrode bit 6B is shorter in length than electrode bit 6A, and also smaller in size than its equivalent electrode in the spot gun embodiment in Fig. 1. Further, the embodiment of Fig. 5 is provided with an automatic actuator 20 consisting of a magnetic or air cylinder instead of the throttle lever 10. The action of this automatic actuator 20 permits electrode 2 on one side of the welding gap to be moved forwards and backwards automatically. Other parts which are identical to those in the embodiment of Fig. 1 have been given the same reference number and their description has been omitted. Next, another embodiment of the rotary position lock 15 will be described with reference to Figs. 6 and 7. The lock 15 of this embodiment is constructed of adjacent parts of the bearing 4 and the base 7 of electrode 3, so that a spring-biased locking pin 17 disposed on the inside of the base 7 fits into the locking holes 16 defined on the circumference of the bearing 4. It is further constructed with a slit 22 defined at the bottom of the base 7, with a clamp handle 21 operatively associated with this slit 22 for permitting the rotary position of electrode 3 to be accurately fixed in position. Other parts which are identical to those in the first embodiment have been given the same reference numbers in Figs. 6 and 7 and their description has been omitted. Because the spot gun of the embodiments described above is constructed such that electrode 2 on one side of the welding gap is mounted on bearing 4 of the frame 1 and can be retractably moved backwards and forwards, and is provided with the pair of electrode bits 6A, 6B aligned with the horizontal central axis 2X, and furthermore because the second electrode 3 is a self-rotating device whose rotary position around the central electrode bit 6A can be set and changed as desired during welding of window frames and other similar structures, the rotary position of electrode 3 can be adjusted by means of a one-touch operation while maintaining the position of the frame 1 connected to the two cables 13 relatively fixed with respect to its original position. If any of the positions 3A-3D shown in Figure 3 are selected, the bracket 8 which is otherwise a hindrance can be moved from its original position; for example if moved to the position 3B of the Figure, side-welding is possible, while if the bracket is moved to 3D, welding in the upward direction can be achieved, while in positions 3A and 3C diagonal and sideways welding is possible. This construction therefore has the considerable advantage that welding can be carried out more conveniently and accurately in all directions with the frame 1 of the spot gun body and the electrode 2 maintained in position. In addition, this construction has the advantage of a simpler construction because there is only one bracket 8 holding the electrodes 6A, 6B. Further insertion of the electrodes into the location to be welded and the gripping of the object to be welded as well as overall handling of the spot gun are much easier than with the devices of the prior art because the electrodes need only be inserted onto the spot to be welded from a direction allowing access to that spot. The above has described the considerable advances made by the spot gun of this invention in terms of ease of spot gun operation and efficiency of use. A third embodiment of this invention will now be described with reference to Fig. 8. Parts which have an identical or similar construction to equivalent parts in Fig. 1 have been given the same reference number and duplicate description has been omitted. Designated by the reference number 30 is a cylinder which is a holder, mounted internally with a retractable piston rod 31. Electrode bit 6A is mounted at the tip of this piston rod 31, while at the rear of piston rod 31 there is mounted a piston 32. At the tip of the cylinder 30 a bearing 4 is constructed on an internal circumference of the insulator part 41, while on the outside circumference of the insulator part 41 there is positioned a covering tube 42 which is connected to the cable connector 5A, this tube 42 having an insulating gap 43 defined between itself and the piston rod 31, and at the same time being combined with a self-rotating rotary part 33 which sits astride the outer circumference thereof. This rotary part 33 is provided with a combined grip/handle 34, which when gripped and rotated by the operator can be used to rotate and alter the position of the bracket 8 by means of the rotary part 33. This rotary device is the same as the clamp handle previously described (see Fig. 7) and it can be clamped at a predetermined position. At the rear of cylinder 30 an air actuator 35 is provided. This air actuator 35 includes an air hose 36 connected to an air compressor not shown in the diagram, an air adjusting valve 37 which is operable to start or stop the air flow, an air introduction chamber 38 provided at the rear of the cylinder 30, and a switch lever 39 for electric operational control of the air flow. 40 is an electric switch while 41 and 44 are parts made of insulating material. In this embodiment, because the holder is cylindrical, it is easier for the operator to grasp; furthermore the electrode 6A can be easily advanced by means of the operation of the air actuator, and in addition the combined grip/handle 34 provided on the rotary part 33 makes it easy to alter the position of the bracket 8.

Claims: A spot gun for a welder machine, comprising: first electrode means (2) retractably mounted upon said gun and comprising a part (6A) extending along a welding axis (2X); second electrode means (3) comprising a bracket (8) and an electrode part (6B) that is carried by the bracket (8) and that extends along said welding axis (2X) in a coaxially, oppositely disposed, manner with respect to said first electrode means (2), so as to define with said first electrode means a welding gap therebetween within which a component to be welded is to be disposed, the second electrode means (3) being so mounted upon said gun that it is rotatable with respect to said first electrode means (2) and about said welding axis (2X) so as to be selectively disposed at any one of a plurality of predetermined circumferentially spaced positions (3A to 3D) with respect to said welding axis (2X) so as to improve the accessibility of said spot gun to said component to be welded during a welding operation; characterised in that the gun further comprises means (15) for positively locking said second electrode means (3) at said any one of said plurality of predetermined circumferentially spaced positions (3A to 3D). A spot gun as set forth in claim 1, wherein said gun further comprises: frame means (1) for supporting said first electrode means (2); and wherein the second electrode means (3) includes a rotary support means (7,33) for rotatably mounting said second electrode means (3) upon said frame means (1). A spot gun as set forth in claim 2, wherein said means (15) for positively locking said second electrode means (3) comprises: a plurality of locking holes (16) defined within the rotary support means (7) and arranged in a circular array about said welding axis (2X); and at least one locking ball or locking pin (17) mounted upon said frame means (1) for mating engagement within at least one of said plurality of locking holes (16). A spot gun as set forth in claim 2, wherein said means (15) for positively locking said second electrode means (3) comprises: a plurality of locking holes (16) defined within said frame means (1) and arranged in a circumferential array about said welding axis (2X); at least one locking pin (17) mounted upon said rotary support means (7) for mating engagement within at least one of said plurality of locking holes (16) defined within said frame means (1). A spot gun as set forth in claim 3, wherein: a plurality of locking balls or pins (17) are provided and are respectively disposed within a corresponding number of locking holes (16). A spot gun as set forth in claim 2, further comprising: means (4) mounting said first electrode means (2) for axial retracting movement along said welding axis (2X); and throttle lever means (11) interconnecting said first electrode means (2) and said frame means (1) for controlling retracting movement of said first electrode means along said welding axis (2X). A spot gun as set forth in claim 6, further comprising: spring biasing means (18) mounted upon said first electrode means (2) for biasing said first electrode means away from said second electrode means (3) along said welding axis (2X). A spot gun as set forth in claim 7, further comprising: bellows-type cover means (19) for covering said spring-biasing means (18) operatively biasing said first electrode means (2). A spot gun as set forth in claim 1, further comprising: means (4) mounting said first electrode means (2) for axial retracting movement along said welding axis (2X); and magnetic actuator means (20) connected to said first electrode means (2) for controlling said axial retracting movement of said first electrode means (2) along said welding axis (2X). A spot gun as set forth in claim 1, further comprising: means (4) mounting said first electrode means (2) for axial retracting movement along said welding axis (2X); and air cylinder means (20, 31, 32) connected to said first electrode means (2) for controlling said axial retracting movement of said first electrode means along said welding axis (2X). A spot gun as set forth in claim 2, further comprising: operative handle means (34), fixedly mounted upon said second electrode (3) for rotating said second electrode to any one of said predetermined circumferentially spaced positions (3A to 3D). A spot gun as set forth in claim 2, further comprising: first handle means (9) integrally formed with said frame means (1) for holding said spot gun within one hand of a welding operator and extending substantially parallel to said welding axis (2X); and second handle means (12) fixedly secured to said frame means (1), and extending substantially perpendicular to said welding axis (2X), for holding said spot gun within the other hand of said welding operator. A spot gun as set forth in claim 2, wherein; said frame means (1) comprises a cylindrical housing (30) within which said first electrode means (2) is coaxially disposed. A spot gun as set forth in claim 13, wherein: said frame means (1) further comprises a piston (31, 32) reciprocably mounted within said cylindrical housing. A spot gun as set forth in claim 14, further comprising: air actuating means (35) operatively connected to said cylindrical housing means (30) and said piston (31, 32) for controlling the movement of said piston within said cylindrical housing.

Inventors: NAKAHIGASI, ISAMU, SUZUKI, YOSHIO
Applicants: SHINANO PNEUMATIC INDUSTRIES INC.
Application year: 1988
Main classification: B23K11
IPC codes: B23K11