Radiant Heat Gun

Abstract

A portable light weight heat unit for delivering instantaneous heat to a local heating area as in brazing, welding and joining operations, comprising a housing having a handle and a reflector provided with means for supporting heat lamps located in the reflector and a trigger switch arrangement for turning the electric power on and off from the lamps and provision for blowing air through the handle and out past the lamps and out of the reflector.

Description

This invention relates to heating devices and more particularly to heat units capable of applying localized heat for periods of time.

An object of the invention is to provide substantially instantaneous local heat to an article to be heated such as in brazing, welding, soldering, or softening operations.

A related object is to provide a heating unit or gun which is light weight and compact and can be hand held and triggered to produce instant local heat for times as short as a few seconds.

In plumbing, welding and brazing operations such as the joining of piping, tubing and fittings and the like it is often desired to concentrate immediate heat on the area to be joined or softened and also to hold and operate the heat unit with one hand while doing this.

In accordance with the present invention there is provided a heat unit comprising a heat lamp holder and reflector and a handle which supports the reflector, and a switching means at the handle by which the electrical power can be turned on and off of the heat lamp means.

A feature of the arrangement resides in the provision of an opening in the reflector into which the article which is to be heated can be inserted. A related feature resides in an arrangement of the reflecting means to concentrate the heat from the lamp means on the area being heated.

A further desirable feature resides in means for injecting cooling air into the handle of the gun in a manner to keep cool the parts of the unit held in the hand and also to provide cooling around the heat lamps. A related feature is to eject air from the reflector and work area to carry away gases which may be generated during the operation.

The foregoing and other features will be better understood from the following detailed description and the accompanying drawing of which:

FIG. 1 is a side view of a heat gun according to this invention;

FIG. 2 is an exploded isometric view showing details of the heat gun of FIG. 1.

Referring to the drawing the heat gun comprises a housing 10, the front end 11 of which is a heat reflector and the rear end 12 of which constitutes a handle. The handle contains a support for the sockets of heat lamps which extend into the reflector 11. The cable 14 is an electrical power line extending into the handle for applying electrical power which can be turned on by a trigger 15 to heat the lamps. The reflector 11 is bifurcated at its forward end to form an upper reflector part 11a and a lower reflector part 11b with a space 16 between the upper and lower reflector parts. A pair of heat lamps extend from the handle, respectively into these upper and lower reflector parts so that the heat from the lamps is reflected from the reflector surfaces and concentrated into the area 16 where the workpiece to be heated is placed when the heat gun is in use.

The various parts and the internal elements of the heat gun are shown in FIG. 2. The handle member is split into a right part containing part 12a and a left part, which mates with the right part, containing part 12b. Internal equipment for the heat gun is placed within the mated parts 12a and 12b, which are held together by screws. There is placed at the forward end of part 12 an insert 13 of a suitable rigid electrical insulating material such as fiber into which there are fixed an upper and a lower socket 18 and 19 respectively, properly threaded internally to receive the threaded ends 20 and 21 of elongated heat lamps 22 and 23, ordinarily of the quartz type, an insulating and heat resisting gasket 24 being placed between insert 13 and the envelopes of the lamps. Suitable openings 25 and 26 are formed through the member 24 to permit the threaded lamp ends to protrude through.

The bottom end of the handle is provided with a pair of openings 27 and 28. There is fitted into opening 28 a bushing 29 into which there is threaded a plug or cap 30 adapted to have fitted to it a hose 31 which carries air under pressure. The other opening 27 is adapted to have fastened into it a fitting 32 which holds an electric cable 33 carrying individual conductors 34, 35 and 36, the conductor 36 being a ground lead for attachment to the housing by a screw for grounding purposes, and the conductors 34 and 35 connecting with a switch box 37 within the handle, in a conventional manner, the switch of which is operated by a trigger lever 38 which protrudes forwardly through a slot 39 formed in the forward depending part of the handle. Conductors 40 and 41 connect with conducting terminal members 42 and 43 respectively which make contact with the terminals of the lamp sockets 18 and 19, so that the lamps will be activated when the trigger switch 38 is actuated to the "on" position.

There are fitted within the handle a pair of vanes or baffles 44 and 45 somewhat separated from each other which extend from the region of the bushing 29 up to the region of the insert 13. Air sent through the bushing from a source of compressed air (not shown) through an air tube 31 is confined between these baffles so that air pressure is built up back of the insert 13, allowing some of the air to pass out through the slot 39 and around the trigger 38 of the switch, while other portions of the air pass through the insert 13 at spaces formed around the sockets 18 and 19 and also through central holes 46 in the insert 13 and 47 in the shield member 24.

To assemble the handle with its contents, the above described parts to be held within the handle are placed in their respective positions as appears from the exploded view, FIG. 2, in one of the handle parts, for example part 12a, and held in place by bringing the other handle part 12b into engagement with part 12a, the two handle parts then being held together by screws.

The bases of the heat lamps are threaded into their respective sockets, and sleeves 50 and 51 are placed over the respective lamps. The ends of the sleeves are slotted at 52 to fit with mating plugs on insert 13. In the case of heat lamps having quartz envelopes, the sleeves 50 and 51 should likewise be of quartz to allow ready radiation of the infra red rays from within the lamps.

Reflector 11 is of unitary construction, having a hub 54 which mates with the open forward end of the handle and is provided with openings 55 and 56 through which the respective lamps and sleeves extend into the reflector cavity. The reflector is divided into an upper and a lower part 57 and 58, respectively, having inner surfaces with a curvature which curves around the respective lamps to reflect and concentrate the heat within the area 16.

To hold the reflector in position, a bolt 59 is passed through a rear opening 60 of the handle and through aligned openings of the insert 13 and the heat shields 24 and into the threads of a block 61 of the reflector; after first tightening up a nut 62 on the bolt to hold the shield 24 against insert 13, which will thus be held securely in place against stops 63 and 64 within the handle.

For the highest efficiency, the upper and lower reflector surfaces should be treated for high reflectability as by use of gold-fired reflectors. The heat lamps can be of the tungsten filament quartz envelope type capable of temperatures up to about 1,350.degree. F. The wattage of each lamp can satisfactorily be 750 to 1,000 watts or more.

The operation of the heat gun should be apparent from the foregoing description thereof. It will be recognized that the article or element to be heated will be inserted within the area 16 whereupon the trigger will be pressed by the operator to heat the lamps for as long as it takes to complete the heating operation, ordinarily only a few seconds.

This heat gun is capable of instantaneous trigger controlled heat on such articles as tubing over a considerable range of diameters, for example one-eighth inch to about 1 inch or more outside diameter. The operation will be fume-free particularly in view of the flow of compressed air through the device and out of the reflector during its operation.

The use of the heat gun is not limited to tubing as many other articles may be joined in only a matter of seconds, such as fittings and other metal joints. The heat gun can likewise be used for such operations as softening plastic to permit easy bending, and to loosen "frozen" threads and the like.

The gun is useful for heating operations on various metals including copper, silver, stainless steel, copper-nickel, as well as other ferrous and non ferrous materials, and is equally useful for bi-metallic brazing.

Claims

1. A heat gun comprising a housing having means for holding a heat lamp means, a handle supporting the lamp holding means and a heat reflecting portion attached to and in front of the handle, so that a heat lamp means attached at the lamp holding means extends into the reflector, the reflector having a curvature which reflects the radiant lamp heat and concentrates it at a work station partially enclosed within the reflector, the reflector having opening means permitting entry into the work station of an object to be heated, the handle containing an electric circuit for energizing the lamp means and a switch therefor, said lamp holding means comprising a support for holding two heat lamps so that they extend into the reflector at opposite sides of the work station whereby the heat from both lamps is concentrated within the work station and means to provide a flow of cooling fluid between said handle and the work station of said

2. The heat gun of claim 1 and means to provide a flow of cooling fluid between said handle and said

3. The heat gun of claim 2 wherein said reflector is bifurcated into a portion above and a portion below the work station and wherein said lamps are supported by said holding means so as to extend into said

4. The heat gun of claim 3 and

5. The heat gun of claim 2 wherein said fluid flow means comprises an arrangement of vanes for channeling the

6. A heat gun comprising a housing including a pistol grip handle and a forwardly-facing upper end spaced forwardly of and above the pistol grip handle; a heat reflector attached to and supported by the housing in front of the handle, said reflector being deeply bifurcated into a first forwardly-extending portion spaced above a second forwardly-extending portion with an open work station located between the two portions and having a rearwardly-facing hub which fits about the forwardly-facing upper end of the housing with a vertically-disposed interior wall preceding the bifurcation and closing off the forward end of said hub, said interior wall having a first lamp-passage hole spaced above a second lamp-passage hole; a lamp holding means disposed within the housing means and comprising a support for holding two heat lamps; two heat lamps, disposed one above the other and carried by the lamp holding means, said heat lamps extending respectively through the two holes of the interior wall of the hub into the lower and upper portions of the reflector; an electric circuit for energizing the two lamps; and a finger-actuated trigger protruding forwardly from the pistol grip handle, said trigger serving to actuate switching means for operating the lamps on

7. A heat gun comprising a housing including a pistol grip handle; a heat reflector attached to and supported by the housing in front of the handle, said reflector being bifurcated into a first portion spaced above a second portion with an open work station located between the two portions; a lamp holding means disposed within the housing means and comprising a support for holding two heat lamps; two heat lamps, disposed one above the other and carried by the lamp holding means, said heat lamps extending respectively into the lower and upper portions of the reflector; an electric circuit for energizing the two lamps; a finger-actuated trigger protruding forwardly from the pistol grip handle, said trigger serving to actuate switching means for operating the lamps on and off; and means for cooling the handle with a gas stream.