GB2305145A

GB2305145A - Pin brazing gun

Info

Publication number: GB2305145A
Application number: GB9619114A
Authority: GB
Inventors: Torsten Bavhammar
Original assignee: Safetrack Baavhammar AB
Current assignee: Safetrack Baavhammar AB
Priority date: 1995-09-12
Filing date: 1996-09-12
Publication date: 1997-04-02
Anticipated expiration: 2016-09-12
Also published as: SE9503160L; SE511193C2; SE9503160D0; GB9619114D0; GB2305145B

Abstract

A pin brazing gun has a body part, a brazing pin shaft 10 longitudinally displaceable in said body part and biased by a spring 12 outwardly from the body part. The brazing pin shaft 10 extends through an aperture in an angle locking washer 8 which is urged by a spring 19 into engagement with a fulcrum 18. A solenoid 1, 2 can be energised to pull, rearwardly, via a shaft 4, the side of the angle locking washer 8 remote from fulcrum 18, so as first to tilt washer 8 to grip shaft 10 and subsequently grip shaft 10 and pull it rearwardly, through a predetermined distance, in order to obtain in use, a predetermined lift of the brazing pin carried by the brazing pin shaft from a workpiece.

Description

DESCRIPTION OF INVENTION Title: "Pin Brazing Gun" THIS INVENTION relates to brazing guns, used in a process where a so-called brazing pin is applied to a metal workpiece by a process in which an electric arc is struck between the brazing pin and the workpiece to generate the heat required to melt the material of the brazing pin adjacent the workpiece after which the brazing pin is thrust against the workpiece to bond thereto. The process is similar to stud welding, save that the brazing pin and workpiece may be of dissimilar metals. However, the invention is also applicable to stud welding and references in this specification to "pin brazing" are also intended to extend to "stud welding" where the context permits.

It is among the objects of the invention to provide a method and arrangement whereby the weight, size and energy consumption of a brazing gun can be reduced, as compared with known brazing guns. It is also an object of the invention to provide a brazing gun having a selfadjusting predetermined height-of-lift, allowing better accuracy being achieved in pin brazing.

Pin brazing is used, inter alia, in connecting electrical conductors, such as cable shoes connected with electric cables, to the rails of electric railways. Such use may also involve the use of protective rings.

One method of achieving automatic height adjustment with a brazing gun is described in Swedish Patent No.

9003708-6 and corresponding GB-2252067. A disadvantage of this gun is the considerable weight and size required with this construction of brazing gun.

A considerable problem today in pin brazing is the adjustment of the height-of-lift, i.e. the spacing between the brazing pin in the extreme end of the gun and the workpiece whilst the electric arc is maintained, this being very important in respect of the final result of the pin brazing operation.

One of the reasons for difficulty in the adjustment of the height-of-lift is the use of different types of brazing pins, cable shoes and protective rings, with varying sizes, so that the adjustment has to be reset for each time a change takes place to different types. The cable shoes may have different heights and the brazing pin length varies. The protective rings adapted to the brazing pin sizes differ.

Another factor is that the length tolerances vary in manufacture and where, for example, the protective rings consist of ceramic material, the length tolerance may, for example, be + 0.3 mm. The length tolerance overall may be considerable if the tolerances are added for all three components (cable shoes, brazing pins and protective rings), and this gives rise to problems in connection with adjusting the height-of-lift. The height-of-lift should be 2 mm for correct brazing.

Excessive height-of-lift causes considerable problems in pin brazing. Excessive height will increase the time during brazing and the arc will be at an angle, for example, to the top of the cable shoe and circulate around the hole in the cable shoe and melt the solder. The result is apparently good melting of the solder, but in actual fact this is a cold brazing. There has been melting in the hole of the cable shoe and the melt lies like a cake on the top of the workpiece and flux and the melted solder has not been drawn between the workpiece and the cable shoe. The capillary force has not acted. Excessive height-of-lift therefore causes cold brazing, which of itself looks perfect but with the brazing pin and the cable shoe not fixed. The workpiece has never been sufficiently heated by the arc and could not therefore draw flux and melted solder by capillary action.This is the most dangerous type of incorrect brazing, since it looks good, but the brazing is not fixed but will gradually work loose.

Excessive height-of-lift can also prevent the electric arc from striking properly. A so-called "blind ignition" is then obtained, in which only the brazing pin capsule (its end) melts and the flux runs out. No brazing is achieved and the brazing pin is usually lost. The workpiece then has to be cleaned and the process restarted with a new brazing pin.

Also, excessive height-of-lift may involve a borderline case between cold brazing and blind ignition if the arc develops normally but the excessive height-of-lift causes the brazing time to be much too long, with the likely result that the working material, e.g. the cable shoe, melts and too much energy is supplied to the workpiece, and this may cause undesirable changes in the workpiece such as the formation of martensite or the like.

Too short a height-of-lift only lifts the brazing pin slightly and not the requisite 2 mm, and this results in too short a time during the brazing process to achieve its proper operation. The brazing solder requires a certain time to be drawn, for example, beneath a cable shoe and too short a height-of-lift gives a process with too short a time. The melted solder has partly deposited on the workpiece, but the solder has not melted to its full extent. This also causes poor brazing, but unlike the previous case it is possible here to see that the brazing is poor. The error can thus be counteracted by removing the poor brazing and making a fresh one. Usually both the brazing pin, cable shoe and protective ring are lost.

Another disadvantage with modern guns is that work is frequently carried out horizontally and there is difficulty in controlling the height-of-lift in this working position due to the fact that the rails are situated on the ground and work is frequently carried out in the dark and poor weather with rain, snow and wind, so it is very difficult to check and adjust the height-oflift.

Another disadvantage of guns on the market today is the relatively considerable power consumption required to lift the brazing pin, and this can be 15 amps and since pin brazing is usually carried out on railways or pipelines and the power source comprises batteries, it is a disadvantage with considerable power consumption per brazing, so that it is not possible to carry out so many brazing operations per battery charge.

Another disadvantage of a heavy brazing gun is that after a number of brazing operations the arms of personnel using such guns become tired and there is an increased risk of faulty brazing operations due to inaccurate angular positioning of the gun with respect to the workpiece.

Considerable weight and size of a pin brazing gun is a clear disadvantage if the equipment frequently has to be transported long distances manually for pin brazing operations. The modern construction of brazing guns consisting of a continuous direct shaft with a long stroke length requires a large heavy electro-magnet to effect the necessary lifting of the brazing pin holder.

Another disadvantage of modern brazing guns is that each brazing operation must be preceded by a check and adjustment of the height-of-lift due to the different sizes and manufacturing tolerances of the brazing pins, protective rings and cable shoes.

There has long been a demand for a gun of smaller size and lower weight, resulting in greater reliability in pin brazing without the need for adjustment and checking on each brazing operation.

One object of this invention, is to eliminate the need to check and adjust the height-of-lift between the workpiece and the brazing pin due to different types of brazing pins, protective rings and cable shoes or manufacturing tolerances when carrying out pin brazing with a pin brazing gun.

Another purpose of the present invention is to provide a gun with a freely movable brazing pin shaft, which is not connected to the working shaft and thus results in a brazing gun with a self-adjusting predetermined height-of-lift.

Another object of the invention is to rigidly connect the brazing pin shaft to the height-of-lift shaft by means of a locking device and for the height-of-lift shaft subsequently to be rigidly connected to the working shaft, the resulting construction requiring a reduced power source. As a result, it is possible to utilise, for example, an electromagnet or solenoid, with a falling characteristic curve and reduced stroke length, giving increased power, for a given energisation, which means that it is possible drastically to reduce the weight and size of the such electromagnet or solenoid.

Another object of the invention is to achieve a brazing gun which is economic in terms of current consumption, for example which only requires a current of 4 amperes, compared with modern guns requiring 15 amperes.

This makes it possible for a greater number of brazing operations to be carried out per battery charge.

According to one aspect of the invention, there is provided a method of obtaining a self-adjusting predetermined height-of-lift in a pin brazing gun, characterised in that a brazing pin shaft is disposed to be freely movable in relation to a working shaft and in that only the brazing pin shaft moves the distance required for adjustment of the height-of-lift between a workpiece and a brazing pin fixed in the brazing pin shaft, and in that the brazing pin shaft is indirectly connected to the working shaft.

According to another aspect of the invention, there is provided a pin brazing gun, as herein defined, comprising a body part, a brazing pin shaft longitudinally displaceable in said body part and resiliently biased outwardly from said body part, said brazing pin shaft extending through an aperture in an angle locking washer or plate which is likewise mounted for movement in said body part in the longitudinal direction of said brazing pin shaft and extends transversely to the axis of said brazing pin shaft, said angle locking plate or washer being biased resiliently into engagement with a fulcrum spaced from the axis of said brazing pin shaft and being displaceable, against resilient bias, away from said fulcrum in a direction corresponding to the direction of inward movement of said brazing pin shaft relative to said body part, and displacing means for engaging and displacing, in said direction, a portion of said angle locking washer remote from said fulcrum, so as to cause initially an increasing angular deviation of the angle locking washer with respect to a plane perpendicular to the axis of said brazing pin shaft, and subsequently, after locking of the angle washer on the brazing pin shaft, bodily displacement of the locking washer and the brazing pin shaft, in said direction, through a predetermined distance, in order to obtain in use, a predetermined lift of any brazing pin carried by the brazing pin shaft from a workpiece.

An embodiment of the invention will now be described in detail with reference to the accompanying drawings, in which: FIGURE 1 is a view in longitudinal section which shows a pin brazing gun embodying the invention in the position of rest, i.e. when not in use, FIGURE 2 shows the pin brazing gun of Figure 1 after the end of the gun, loaded with a brazing pin, has been pressed against a workpiece and before the pin has been lifted from the workpiece to establish an electric arc of the desired length, FIGURE 3 shows the gun after the arc has been struck and the pin has been lifted, FIGURE 4 shows a variant gun with a rotating magnet as the driving means for the pin holder, and FIGURE 5 shows a further variant with pneumatic operation as the driving means.

Figure 1 shows a pin brazing gun in the position of rest.

The gun comprises, in common with known brazing guns, a hollow body part including a handle, with an operating trigger. Mounted within the hollow body part is a driving means (also referred to herein as a power source) for lifting a brazing pin shaft 10 carrying a brazing pin 24, from a workpiece to establish an electric arc. The brazing pin shaft 10 is slidable longitudinally in the body part. In the embodiment of Figures 1 to 3 the driving means or power source comprises an electro-magnet or solenoid 1 with an armature 2. The electro-magnet 1 is disposed in the rear part of the gun and its armature 2 is secured by a fixing means 3 to the rear end of a height-oflift shaft 4 which extends parallel with the brazing pin shaft 10 through a compression spring 5 and through a carrier sleeve 7. A lock nut 6 on shaft 4 provides an abutment for the forward end of sleeve 7.At its forward end, shaft 4 abuts against an adjusting screw 17. An angle locking washer 8 within the hollow body has a central aperture receiving the brazing pin shaft 10 which extends freely through said central aperture in the washer 8 in the "at rest" position of the gun shown in Figure 1. The shaft 4 extends through a further aperture in washer 8, as a free fit. The spring 5 bears at one end against the plate 8 and at its other end against the armature attachment which is fixed to the armature 2 and is fixed at 3 to shaft 4.

The brazing pin shaft 10 is hollow and an electrically conductive rod 11 extends co-axially within the shaft 10 but is spaced radially therefrom and is electrically insulated from the shaft by insulating sleeves at the front and rear of the shaft, these sleeves having flanges 14. The rod 11 projects forwardly and rearwardly from the shaft 10 and at its rear end carries a power supply cable connector 9 secured by a nut and connected with a flexible cable (not shown) connected with a source of current for the electric arc. At the forward end of shaft 10, at the front of the gun, a brazing pin holder 22 is secured to the front end of rod 12.

The shaft 10 extends through a bore in a front wall of the body part of the gun, being slidably received in a bearing sleeve 13 fitted in said bore, this bearing sleeve having a flange engaging the rear surface of said front wall. A hollow, tubular ceramic ring holder 23, coaxial with shaft 10, extends from the front wall of the body part and surrounds the holder 22 but is spaced radially therefrom. The holder 23 holds, at its front end, a ceramic ring 25 shown surrounding a brazing pin 24 held by holder 22.

The brazing pin shaft 10 extends through a helical compression spring 12 which at its forward end abuts a locking ring (Seeger securing) 16 fixed to shaft 10, and at its rear end abuts a bulkhead wall of the body part, the shaft 10 extending slidably through this bulkhead wall through a further bearing bush 13 having at its front end a flange engaged by spring 12. In the rest position illustrated, the locking ring 16 abuts the flange of the front bearing bush 13. The height-of-lift shaft 4 and its sleeve 7 pass slidably through a bearing bush 15 recessed in a bore in said bulkhead wall. The position of the height-of-lift shaft 4 can be adjusted manually by the adjusting screw 17 and the position of the angle locking washer 8 can be adjusted by an adjusting screw 18 which provides a fulcrum for the washer 8, both screws being adjustable from outside the gun.A tension spring 19 is secured at one end to the washer 8 and at its forward end to the front wall of the body part. At the rear of the gun is a knob 20 adjustable for setting different heights-oflift since certain brazing pins require special different height-of-lift adjustments such as 1.5 mm and 2.5 mm. A damping means 21 is also provided for the armature 2.

Figure 2 shows the pin brazing gun with a brazing pin fitted to the holder 22 after the forward end of the gun, with the brazing pin, has been pushed against a workpiece 27 to which a cable shoe 26 is to be attached, so that the shaft 10, holder 22, and brazing pin have been pushed rearwardly relative to the body part whilst the shoe 26 is held against the workpiece by the ceramic ring 25.

The brazing pin 24, in the position shown is still in contact with the workpiece. This is the position of the apparatus just before the brazing pin is lifted from the workpiece to establish the desired electric arc between the pin and the workpiece. Thus, in Figure 2 it can be seen that at the very front the ceramic ring 25 abuts a cable shoe 26 and the brazing pin 24 abuts the workpiece 27. The gun has been pressed down against the workpiece 27, as mentioned above and as a result the brazing pin shaft 10 has been pushed rearwardly into the gun through the washer 8 in which, in this position, the shaft 10 is freely movable. The springs 5 and 19 prevent the washer 8 from following the brazing pin shaft 10 rearwardly when the electro-magnet is not actuated. The compression spring 12 opposes the pressing in of the brazing pin shaft 10.Thus, as a result of the action of the compression spring 5 and spring 19 only the brazing pin shaft 10 moves rearwardly in the gun at this stage.

Figure 3 shows the pin brazing gun after the brazing pin has been lifted from the workpiece and the arc ignited, i.e. when the trigger has been actuated and current supplied to the current cable connection 9 and the lead 11 at the same time as a control or energising current is fed to the electro-magnet 1 and the working armature 2 is thereby pulled rearwardly. The height-of-lift shaft 4, which is fixed at 3 to the armature 2 is likewise pulled rearwardly causing the carrier sleeve 7, backed by nut 6 on shaft 4, to urge the part of washer 8 through which the shaft 4 passes, rearwardly.Since the washer 8 is held at its opposite side against fulcrum 18 by spring 19 initially, the washer 8 is initially caused to tilt about this fulcrum so as to increase the angle A between the washer 8 and the axis of the brazing pin shaft 10 until the edges of the central aperture in the washer 8 engage the brazing pin shaft 10 thus effectively fixing the washer on the shaft 10. The firmness of engagement of washer 8 with shaft 10 depends partly on the central hole diameter of the washer 8 as compared with the outside diameter of the brazing pin shaft 10, and partly on the size and quality of the material of the washer 8.

After such engagement of washer 8 with shaft 10, during continued rearward movement of armature 2, the armature, the height-of-lift shaft 4, the washer 8 and the brazing pin shaft 10 now continue to move rearwardly as a unit in the gun until a rearward projection of the armature 2, extending rearwardly from the electro-magnet coil, abuts the damping means 21 which in turn abuts the adjustment knob 20. In the meantime the arc between the brazing pin 24 and the workpiece 27 has ignited and the brazing process continues. (The adjustment knob 20 comprises a face cam which provides an adjustable end stop for the armature).

When the predetermined quantity of energy has been delivered and thus the brazing time has elapsed, the driving unit breaks the current both to the magnet 1 and the lead 11, so that the arc is extinguished. The electromagnetic force on the armature 2 disappears and the force in the tension spring 19 together with the compression force in the compression spring 12 causes the shafts 10 and 4 and the washer 8 to move forwardly in the gun. The washer 8 abuts adjustable fulcrum screw 18, which causes the angle A between the washer 8 and the brazing pin shaft 10 to reduce as shaft 4 and sleeve 7 move further forwards and thus causes the engagement of the washer with the brazing pin shaft 10 to cease. The forward end of the height-of-lift shaft 4 is now intercepted by the adjusting screw 17 and only the brazing pin shaft 10 continues forwardly under the action of spring 12.The forward movement of shaft 10 causes the remaining parts of the brazing pin 24 to be pressed down into the melt at the brazing site. Forward movement of shaft 10 is stopped when the locking ring 16 meets the flange of the forward bearing bush 13. This completes the brazing pin gun brazing process.

After a long period of use, wear may occur in the actual locking mechanism. This can be counteracted by means of the adjusting screw 17 and the adjusting screw 18.

The purpose of adjusting screw 17 is to adjust the angle A between the washer 8 and the centre of the brazing pin shaft 10 so that the washer 8 engages when the height-oflift shaft 4 moves rearwardly. The adjusting screw 18 is used to adjust the height-of-lift, which is normally required to be 2 mm when the adjusting knob 20 is in the zero position.

Figure 4 shows a variant pin brazing gun using an electromagnet 28 with an armature 29 which is rotatable about the axis of shaft 10 instead of being movable along that axis as in Figures 1 to 3. In this variant, the armature 29 has a peripheral flange or cam extending helically about said axis and which engages in a lateral slot in the height-of-lift shaft 32 so that rotation of armature 29 in one direction causes the shaft 4 to be drawn rearwardly. Counter-rotation, for example under the action of a torsion spring (not shown) conversely produces forward movement of shaft 4. Otherwise the structure and functions are the same for the gun described with reference to the previous Figures.

Figure 5 shows a further variant pin brazing gun with a pneumatic actuator for lifting the brazing pin shaft. The actuator comprises a pneumatic cylinder 30 which acts on a piston rod 31 connected by an arm with shaft 4. This type of gun is the most energy-saving model.

Here again the structure and functions are otherwise the same as described above with reference to Figures 1 to 3.

It will be understood that other driving means apart from the solenoids or pneumatic actuator referred to above may be used for lifting the brazing pin shaft in other embodiments.

The preferred embodiments of the present invention therefore provide a pin brazing gun with a freely moving brazing pin shaft 10 which is not rigidly connected to the armature 2 or its equivalent and adjustment takes place when the brazing pin shaft 10 is pressed down against a workpiece. A locking means 8 rigidly connects the brazing pin shaft 10 to the height-of-lift shaft 4, which is already rigidly connected to the armature 2, and when current is fed to the electro-magnet 1 and its armature 2 is pulled in, the height-of-lift shaft 4 will press on the washer 8 which then follows the movement of the height-oflift shaft 4 rearwardly and the tension spring 19 will then counteract the movement of the washer 8 and increase the angle A between the brazing pin shaft 10 and the washer 8 until the washer 8 engages around the brazing pin shaft 10 with a lever effect.The armature 2, height-of-lift shaft 4 and the brazing pin shaft 10 now operate as a single unit. When the predetermined quantity of energy has been delivered, the current supply to the magnet is interrupted, the armature and shafts 4 and 10 move forwardly, the washer 8 being intercepted by the adjusting screw 18 so that the angle A between the brazing pin shaft 10 and the washer 8 is reduced and the engagement around the brazing pin shaft 10 ceases. The height-of-lift shaft 4 is intercepted by the adjusting screw 17 and then only the brazing pin shaft 10 moves forward until the locking ring 16 meets the flange of the forward bearing bush 13. The remaining part of the brazing pin is now pressed down into the melt at the welding site.

The above principle with a freely moving brazing pin shaft allows a brazing pin gun construction with a smaller electro-magnet which with a reduced stroke length gives an increased force. The result is a pin brazing gun of reduced size and weight, which is energy-saving and has a self-adjusting predetermined height-of-lift.

Claims

1. A method of obtaining a self-adjusting predetermined height-of-lift in a pin brazing gun, characterised in that a brazing pin shaft is disposed to be freely movable in relation to a working shaft and in that only the brazing pin shaft moves the distance required for adjustment of the height-of-lift between a workpiece and a brazing pin fixed in the brazing pin shaft, and in that the brazing pin shaft is indirectly connected to the working shaft.

2. A method according to claim 1, characterised in that by the action of a locking means between the brazing pin shaft and the height-of-lift shaft the same are controlled to move simultaneously together with the working shaft during its working time and in that the working shaft is rigidly connected to the height-of-lift shaft.

3. A method according to claims 1 and 2, characterised in that with the brazing pin shaft freely movable in relation to the working shaft a power source, e.g. a magnet, is used which has a reduced length of stroke to give greater power, so that the weight, size and current consumption are greatly reduced.

4. A method according to claims 1 to 3, characterised in that the power source comprises a rotating magnet or pneumatic operation.

5. A pin brazing gun (as herein defined) with a selfadjusting predetermined height-of-lift, characterised in that a brazing pin shaft (10) is pressed against a workpiece (27), only the brazing pin shaft (10) being guided into the brazing pin gun and the height-of-lift between the brazing pin (24) and the workpiece (27) is recorded and in that when the control current actuates a magnet (1) a working shaft (2) is pulled into the magnet housing (1), a height-of-lift shaft (4) axially rigidly connected by a fixing means (3) to the working shaft (2) actuating an angle locking washer (8) to follow the movement of the height-of-lift shaft (4) rearwardly in the pin brazing gun, a tension spring (19) counteracting the rearward movement and an angle (A) between the angle locking washer (8) and the brazing pin shaft (10) increasing until the angle locking washer (8) engages around the brazing pin shaft (10) with a lever effect, the working shaft (2), height-of-lift shaft (4) and brazing pin shaft (10) continuing as a single unit rearwardly in the pin brazing gun until the working shaft (2) abuts the damping means (21) and the adjustment knob (20) and when the predetermined quantity of energy has been delivered to the brazing site and the brazing time has expired the current to the magnet (1) is broken and the force on the working shaft (2) disappears, whereafter the tension spring (19) and the compression spring (12) act on all the shafts (2, 4, 10) and the angle locking washer (8) to move forward in the pin brazing gun, the washer (8) being intercepted by the adjusting screw (18), resulting in the angle (A) between the washer (8) and the brazing pin shaft (10) reducing and the engagement around the brazing pin shaft (10) ceasing. The height-of-lift shaft (4) is intercepted by the adjusting screw (17) and the brazing pin shaft (10) continues forwardly until a locking ring (16) meets the flange on a bearing bush (13) and the remaining part of the brazing pin (24) is pressed down into the melt at the brazing site.

6. A pin brazing gun according to claim 5, characterised in that the driving source in the gun is a rotating magnet (28) with a rotating working shaft (29) which acts on a height-of-lift shaft (32).

7. A pin brazing gun according to claim 5, characterised in that the driving source in the gun is the pneumatic cylinder (30) which acts on a piston rod (31) and the latter is connected to a height-of-lift shaft (4).

8. A pin brazing gun, as herein defined, comprising a body part, a brazing pin shaft longitudinally displaceable in said body part and resiliently biased outwardly from said body part, said brazing pin shaft extending through an aperture in an angle locking washer or plate which is likewise mounted for movement in said body part in the longitudinal direction of said brazing pin shaft and extends transversely to the axis of said brazing pin shaft, said angle locking plate or washer being biased resiliently into engagement with a fulcrum spaced from the axis of said brazing pin shaft and being displaceable, against resilient bias, away from said fulcrum in a direction corresponding to the direction of inward movement of said brazing pin shaft relative to said body part, and displacing means for engaging and displacing, in said direction, a portion of said angle locking washer remote from said fulcrum, so as to cause initially an increasing angular deviation of the angle locking washer with respect to a plane perpendicular to the axis of said brazing pin shaft, and subsequently, after locking of the angle washer on the brazing pin shaft, bodily displacement of the locking washer and the brazing pin shaft, in said direction, through a predetermined distance, in order to obtain in use, a predetermined lift of any brazing pin carried by the brazing pin shaft from a workpiece.

9. A pin brazing gun according to claim 8 wherein the starting position relative to said body part, of said displacing means is adjustable.

10. A pin brazing gun according to claim 8 or claim 9 wherein the position of said fulcrum is adjustable.

11. A pin brazing gun according to any of claims 8 to 10 wherein the finishing position of said displacing means relative to said body part is adjustable.

12. A pin brazing gun substantially as hereinbefore described with reference to and as shown in Figures 1 to 3 of the accompanying drawings.

13. A pin brazing gun substantially as hereinbefore described with reference to and as shown in Figure 4 of the accompanying drawings.

14. A pin brazing gun substantially as hereinbefore described with reference to and as shown in Figure 5 of the accompanying drawings.

15. Any novel feature or combination of features disclosed herein.