Apparatus For Heat Operating A Workpiece With The Aid Of An Optical Projection Of A Radiation Source

Abstract

An apparatus for the heating, melting, welding, brazing, cutting and the like of a workpiece with the aid of the optical projection of a radiation source. The radiation source is disposed within a radiation focusing chamber at one focal point thereof and the radiation therefrom exits the chamber through a radiation outlet to impinge on a second external working focal point. A pressurized gas, which may be a cooling gas, protective gas or reactive gas may be introduced into at least a portion of the chamber. The gas discharges through the radiation outlet and prevents entry into the chamber of damaging vapors which develop during use of the apparatus. The chamber may be divided by a radiation permeable partition into a pair of compartments; a first containing the radiation source and a second having the radiation outlet. The gas may be introduced into the first compartment to exit through an aperture in the partition into the second compartment for discharge through the outlet. Alternatively a first gas may be introduced into the first compartment and a second gas may be introduced into the second compartment whereby both gases, either mixed or unmixed are discharged through the outlet. In other embodiments, the first compartment may be sealed and the gas or gases introduced directly into the second compartment. The second compartment may include a narrow tube disposed substantially coaxial with an imaginary line interconnecting the foci for directing a concentrated stream of a gas toward the workpiece. A fiber optic rod may be mounted at the radiation outlet to provide a concentrated radiation at a point removed from the second focus. The rod may have a bore for passage of the pressurized gas from the chamber.

Description

The invention relates to an apparatus for the heating, melting, welding, brazing, cutting and the like, of a workpiece, with the aid of an optical projection of a radiation source, with the workpiece being placed in a focal point, and the light source being disposed within the radiation focusing chamber.

During working with apparatus of the aforesaid type, vapors develop which have a detrimental effect in that they penetrate into the chamber and precipitate on the internal surfaces of the chamber and hence impair the mirror effect of the chamber. After a short while, this renders the chamber useless.

Attempts have been made to ameliorate this condition by providing near the exit outlet of the chamber a protecting disc, for instance composed of quartz glass; but these attempts have not met with success, because the vapors precipitated on the protective disc, and impaired the radiation permeability thereof after only a short use. While it is possible to clean the protective disc with a suitable cleaning arrangement, the aggressive ingredients within the vapors often attack the material of the protective disc again impairing the radiation permeability thereof. It needs further to be considered that as the radiation permeability is impaired, the radiation absorption increases at the inverse ratio. Thus the protective disc may be heated sufficiently so that it will melt.

It is accordingly among the principal objects of the invention to avoid the above-noted disadvantages.

It is another object of the invention to provide an apparatus of the aforesaid type which is highly wear resistant and permits the continuous working over long periods of time without interruption.

Further objects and advantages of the invention will be set forth in part in the following specification and in part will be obvious therefrom without being specifically referred to, the same being realized and attained as pointed out in the claims hereof.

Generally speaking, these aims are achieved in accordance with the instant invention by the arrangement of a gas discharge at the chamber, which discharge is directed towards the workpiece.

The gas which is discharged, in accordance with an embodiment of the invention, from the chamber prevents due to its corresponding overpressure the entrance of vapors into the chamber.

It is also possible to conduct the gas on the exterior to the discharge outlet of the chamber and thus to block the entry into the chamber of the damaging vapors.

The exiting gas may, however, furthermore be used for cooling, for instance of the radiation source. Furthermore, the gas may be used for varying the temperature at the workpiece simply by varying the rate of flow of the gas; for instance, the gas that has been heated in the chamber may be used for heating the material where the material is synthetic resin to be welded.

The gas may furthermore be used as a protective gas, for instance during the welding of easily oxidizing material.

Where oxygen is used as the gas, it may be utilized for flame cutting in connection with the workpiece.

An apparatus of the above-described type usually is composed of the chamber, that is formed of two material parts, one of which has an ellipsoid shape and the other a spherical shape, and preferably has a conical discharge portion that serves as a radiation guide. The gas may be conducted directly into the chamber, or into the discharge portion thereof; if it is conducted into the discharge portion, it is advantageous to arrange a radiation permeable partition, such as a disc, or a lens, between the chamber and the discharge portion, and the partition may have an aperture for the passage of the gases.

The chamber itself may in this manner be closed hermetically, thereby reducing greatly the gas consumption.

The aperture in the disc or collective lens is particularly suitable where it is desired to conduct towards the chamber exit two different gases, for instance cutting oxygen and a protective gas to surround the oxygen. It is particularly suitable, in connection with this example, to conduct the cutting oxygen near the rearward end of the chamber, so that the oxygen may be heated in the chamber and at the same time will have a cooling effect on the chamber. In the aperture of the partition there may be arranged a small tube that conducts the oxygen directly towards the outlet opening of the discharge portion. The second gas, for instance, an inert gas, may be conducted to the discharge portion from the side. Upon exiting, the central oxygen will be concentrically surrounded by the inert protective gas.

The instant invention, as previously alluded to, is suitable for many different operations on the workpiece. Generally, however, it has been found suitable to place the workpiece within the free focal point of the chamber, as in the other focal point of the elliptical part of the chamber there is arranged the radiation source; this arrangement of the workpiece has the advantage to achieve the highest heat concentration in that position.

It is also possible to move the workpiece somewhat away from the free or working focal point, for instance in order to vary the magnitude of the heat transmitted to the workpiece. It is furthermore possible to relocate the effective position of the working focal point by the application of suitable radiation guides. In accordance with one embodiment of the instant invention, there is accordingly provided near the outlet of the chamber or of the discharge portion thereof, a fiber optic.

The utilization of such a fiber optic makes it possible to provide a concentrated radiation energy even at a greater distance from the radiation generator, such as the chamber. The apparatus which includes the fiber optic in accordance with the instant invention is particularly suitable for surgical operations, for instance for melting cells in brain surgery. This arrangement has the advantage to avoid the occurrence of disturbing electromagnetic stray fields, that had been experienced with apparatus of this type in the past.

As the heat radiation converges after the exit from the fiber optic, it is recommended to arrange near the exit surface of the fiber optic a collective lens.

The instant invention is furthermore useful for the welding of synthetic resins.

The instant invention also finds use in the glass industry. For instance, it may suitably be employed, for instance, for the closing by fusing of evacuated receptacles, ampuls and the like. The invention also provides for welding within the evacuated receptacles.

The fiber optic which is connected to the chamber structure may either be of the rigid or flexible type. Glass fiber rods, for instance, are composed of several thousand light guide fibers which are fused together throughout their entire lengths and form a rigid system. Also the use of a rigid or flexible fiber optic cross section adjuster is feasible. It includes a bundle of light guide fibers which is united at both ends to different cross sections. The concentration may in this manner be changed very simply and with but few losses. One-armed or multiple-armed flexible light guides may be utilized to propagate the radiation energy to any desired paths. Where multiple-armed light guides are used, they permit the distribution of the radiation energy onto several objects. Due to the flexibility of the individual arms, any relative motion between the radiation source and the radiation recipient may thus be met in a simple manner.

The fiber optic furthermore permits the guiding of a protective gas near the exit surface thereof. For instance, it is advantageous, in order to avoid the precipitation of damaging vapors at the frontal surface of the fiber optic, to provide in the fiber optic a central exit passage for the gas.

A further possibility, in accordance with the invention, for conducting the gas provides for a separate gas pipe on the exterior of the fiber optic. The fiber optic communicates interiorly with an annular shell that is located near the frontal surface of the fiber optic and has a central opening, so that the gas forms a shielding curtain for the frontal surface. This embodiment is particularly suitable where the fiber optic is formed in accordance with a bent rod.

A further modification provides that the gas conduit forms a sleeve that surrounds the fiber optic and defines therewith an annular space, and the gas emanates from that space in an annular stream.

The foregoing and other objects of the invention will be best understood from the following description of exemplifications thereof, reference being had to the accompanying drawings, wherein:

FIG. 1 is a fragmentary schematic elevational view of an apparatus in accordance with an embodiment of the invention;

FIG. 2 is a large-scale elevational view, partly in section, of a projection chamber of the embodiment shown in FIG. 1;

FIG. 3 is a large-scale elevational view, partly in section, of the embodiment of FIG. 2;

FIG. 4 is a schematic sectional view of a chamber structure, embodying a modification;

FIG. 4a is a fragmentary schematic sectional view similar to a portion of FIG. 4 but embodying a modification.

FIG. 5 is a fragmentary schematic sectional view, similar to a portion of FIG. 4, but embodying a further modification;

FIG. 6 is a fragmentary sectional view similar to FIG. 5, but embodying a further modification;

FIG. 7 is a fragmentary sectional view, similar to FIG. 4 but embodying still a further modification;

FIG. 8 is a schematic sectional view, similar to FIGS. 4 and 7, but embodying another modification;

FIG. 9 is a schematic sectional view similar to FIG. 8, but showing a further modification; and

FIG. 10 is a fragmentary schematic sectional view, similar to a part of FIG. 9, but embodying still another modification.

The embodiment shown in FIGS. 1-3 may, at the choice of the operator, be used for either welding or flame cutting. It comprises a chamber structure 10 that is mounted on an arm 11 which is pivoted to a sleeve, the latter being movable on a column 12. A screw 13 serves to arrest the arm 11 in a selected position. The column 12 is mounted on a table 14 on which there is deposited a workpiece 15.

As best shown in FIGS. 2 and 3, the chamber of the chamber structure 10 comprises two parts, namely an ellipsoid part 16 that has a circular cross section, and a spherical part 17. The parts 16 and 17 are interconnected by means of flanges 18 and 19, respectively, which are held together by means of screws 20. The inner surfaces 21 and 22 of the parts 16 and 17 are lined with a mirror layer, preferably composed of gold. In one focal point of the ellipsoid part 21, there is mounted the radiation source 23 that delivers the energy for the operation to be performed on the workpiece 15. The focal point for the source 23 at the same time constitutes the center of the spherical portion 17.

The radiation source may be halogen-quartz lamp, or a gas-discharge lamp, or an arc lamp, or the like. The choice of the radiation source, and of the wave length of the radiation depends on the use to which the apparatus is put. For instance, the apparatus may be used to propagate radiation in the infrared portion of the spectrum, or within the ultraviolet portion of the spectrum.

The mounting of the radiation source 23 is indicated in FIG. 3, and includes mounting means 30. It is primarily composed of ceramic tubes that surround the current carrying conductors, and the ceramic tubes have a mirror surface to avoid the absorption of heat radiation. The ceramic tubes are mounted at the flange 18 by means of a clamp 32 and screws 33. To connect the radiation source to a source of current, there is provided a conductor 35 and a connector 36. The conductor 35 connects the connector 36 with a switching unit 34 which, in turn, is connected to an electric source. The voltage and voltage time may be adjusted by means of knobs 37 and 38, respectively.

The rays radiated by the radiation source 23 arrive, partly directly and partly indirectly by reflection from the internal surfaces 21, 22, at the second focal point 24 of the ellipsoid part 16. To illustrate the paths of the radiation more fully, three characteristic rays have been shown in FIG. 3. A first ray 66 proceeds directly from the source 23 to the focal point 24. A second ray 67 is reflected by the surface 21 and thence is reflected to the focal point 24. A third ray 68 is reflected back onto itself from the surface 22 of the spherical part 17, and proceeds back through the focal point of the source 23 to the face 21 from where it is reflected into the focal point 24.

The focal point 24 is disposed outside the chamber and constitutes the so-called working focal point. As the greatest heat concentration exists in the working focal point 24, the workpiece 15 is usually arranged there, as shown in FIG. 1.

The heat rays that are radiated by the source 23 are discharged through an outlet 25 of the chamber structure 10. A discharge portion 26 is provided for collecting in an exact manner the heat rays in the focal point 24. The discharge portion 26 is mounted on the part 17, by means of a flange 27 and screws 28. The discharge portion 26 has an external as well as an internal conical surface, and its internal conical surface 29 is lined with a strongly reflecting layer, similar to that of the internal surfaces 21 and 22 of the parts 16 and 17, respectively.

The heat concentration in the focal point 24 causes melting of the workpiece 15 which, in turn, generates vapors. These vapors have the tendency to enter into the chamber through the outlet 39 (see FIG. 4) of the discharge portion 26 and to precipitate on the inner mirror surfaces 21, 22 and 29. By this precipitation, these internal surfaces gradually would lose their reflecting capability, which would result in a relatively short time in a reduced efficiency and subsequent total uselessness of the apparatus.

To meet that danger, the invention provides for the supplying of gases. In accordance with an embodiment of the invention, gas is supplied to the interior of the chamber, and is discharged through the outlet 39 in the direction of the workpiece 15, and by this overpressure prevents the damaging vapors from entering into the interior of the chamber structure 10.

As best shown in FIG. 1, two conduits 40 and 41 are provided for the gas, that are connected to gas bottles 42 and 43, respectively. The gas may be an inert protective gas, and it is sufficient to conduct the inert gas into the discharge portion 26, by means of the gas conduit 40. For flame cutting, the gas will be oxygen. For oxygen, it is recommended to guide the gas directly into the interior of the chamber 16, 17; and the oxygen may be heated in the interior of the chamber, thereby greatly improving the efficiency of the subsequent flame cutting.

Where the gas is conducted into the discharge portion 26, the gas consumption may be held to a minimum by the provision of a partition between the chamber 16,17 and the discharge portion 26. A partition of this type may be a collective lens or a disc. Such a protective partition disc 44 is shown in FIG. 2. It needs to be to a large extent radiation permeable and hence suitably be composed of quartz glass. The partition 44 furthermore protects the interior surfaces of the parts 16,17 from any occurring sprays which cannot be prevented by the exiting gases from entering through the outlet 39. Furthermore, the chamber 16,17 may be closed by the partition 44 hermetically to such an extent that the chamber 16,17 may be evacuated so that radiation source, for instance a tungsten coil may be used without protective shield in the chamber 16,17.

The two gases, namely a protective gas and oxygen may, depending on the use to which the apparatus is put, be guided towards the chamber 16,17 selectively and alternatively. For certain purposes, however, it is most suitable to use both gases simultaneously. Furthermore, it is possible to provide for air cooling of the chamber 16,17, for instance as shown in FIG. 1, where cooled air is pressed into the chamber 16,17 by means of a blower 45 and exits through a discharge nozzle 46.

Simultaneous conducting of oxygen and a protective gas is shown in the modifications of FIGS. 4-7. In the exemplification of FIG. 4, the part 16 is provided near its rear with a connector for receiving oxygen. The oxygen flows through the chamber 16,17 and cools the interior thereof and at the same time is heated. Subsequently, the oxygen exits through an aperture 46 in the partition 47, and a little tube 48 is fitted into said aperture 46a for conducting the oxygen to the outlet 39 of the discharge portion 26. The discharge portion 26 has on its side a receiving connector 49 by means of which the protective gas is conducted into the interior of the discharge portion 26. At the outlet 39, the exiting oxygen will be surrounded by an annular stream of the protective gas. A modification of the apparatus of FIG. 4 is shown in FIG. 4a. In this modification, the partition is formed as a lens 47a having an aperture 46a in which a tube 48a is fixed. The gas is conducted through tube 48a and exits from outlet 39.

In a similar manner, the exiting of both gases will be accomplished with the modifications of FIGS. 5, 6 and 7.

In FIG. 5, the oxygen is not brought into the chamber 16,17, but is conducted into the discharge portion 26, by means of a connector 52 and a passage 53 that is formed in the partition 54 that communicates interiorly with a discharge tube 55 that leads the oxygen to the outlet 39 in a concentrated stream towards the workpiece 15.

In accordance with FIG. 6, the oxygen is also delivered directly into the interior of the discharge portion 26, by means of a connector 50 and a tube 51 that is bent at a right angle leading axially to the outlet 39 and discharges the oxygen in the direction towards the workpiece 15.

In FIG. 7, the oxygen is conducted into the chamber 16,17 from the side, by means of a connector 56 and a right-angled tube 58 that leads to the outlet 39 for discharging the oxygen in a direction towards the workpiece near the focal point 24. The oxygen, though conducted through the chamber 16,17, is not permitted to expand in that chamber, but merely passes through the chamber within the tube 58.

In FIG. 8, there is shown a chamber 59 that has an ellipsoid part 60 and a spherical part 61. The ellipsoid part 60 is far larger than the spherical part 61. The chamber is so arranged that the aforesaid working focal point at 24 is disposed on the outermost point of the spherical part 61. To the outlet 62 of the chamber 59 there is connected a fiber optic that comprises a conically tapering glass fiber rod 63. The rod 63 is composed of a multitude of fibers, and serves the purpose to transfer the aforesaid working focal point 24 to the point at 24a. Thus the real focal point 24a is at the end of the rod 63. Such a transfer of the working focal point to a more remote position has the advantage to render accessible for the radiation projection certain locations which are otherwise difficult to reach. Hence the instant apparatus can be used for medical purposes, for instance for brain surgery.

In order to avoid the precipitation of damaging vapors on the front surface 64 of the rod 63, the rod is provided with an axial elongated passage 65 that serves for the conduction of the protective gas to the surface 64. The protective gas is conducted into the chamber 59 by means of a connector 66 and is discharged from the interior of the chamber 59 into the passage 65.

In accordance with the modification of FIG. 9, the glass fiber rod 69 is mounted at the outlet of the discharge portion 26. To illustrate the possibilities afforded by the use of fiber optics, the glass rod 69 is shown bent in FIG. 9. Where a straight rod is used, it will extend without bending, as shown in broken lines at 70.

Independently of its form, whether bent or straight, the working focal point is transferred by the glass fiber rod to the frontal surface 71 of the rod 69.

In order to avoid precipitation of damaging vapors on the frontal surface 71, a protective gas is conducted to said surface 71. In this embodiment, the protective gas is conducted in a pipe 72 externally of the glass fiber rod 69. The pipe 72 ends in an annular channel 73 that has a central bore 74 through which the gas finally exits.

In accordance with the modification of FIG. 10, the protective gas is conducted to the frontal surface 71 in a conduit that includes a sleeve 75 which surrounds the glass rod 69 and forms therewith an annular space. The gas thus constantly encircles the exterior surface of the glass rod 69. This promotes a cooling of the glass rod 69. Near the frontal surface 71 of the glass rod 69, the sleeve 75 forms an annular channel with an enlarged portion 77 and a subsequent reduced portion 78, in order to bundle sharply the exiting gas stream.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Claims

Having thus described the invention, what I claim as new and desire to be

1. An electric apparatus for heating, melting, welding, soldering and cutting work pieces by focusing reflected radiation from a source thereof towards a portion of the work piece, comprising a reflector chamber structure defining a pair of foci, one focus being located within said chamber and the other located at a point outside said chamber, a source of radiation disposed at said one focus within said chamber, means defining a radiation outlet for said chamber, and including a tapered reflective portion, for the projection of the reflected radiation toward said other focus to heat at least said portion of said work piece, and a gas nozzle including a narrow cylindrical tube disposed within said tapered portion and substantially coaxial with an imaginary line interconnecting said foci and being fed from a gas source and directing a concentrated stream of said gas towards the heated portion of said work

2. In an apparatus, as claimed in claim 24, and a conduit conducting said

3. In an apparatus, as claimed in claim 1, a radiation permeable partition

4. In an apparatus, as claimed in claim 3, said partition including a lens.

5. An electric apparatus, as claimed in claim 3, said gas nozzle including a tubular part upstream of said cylindrical tube and disposed within said

6. An electric apparatus, as claimed in claim 1, and a second nozzle operable to be fed from a second gas source and to feed said second gas into said tapered portion from where the second gas will be discharged

7. An electric apparatus, as claimed in claim 1, and gas supply means operable to deliver a second gas from a second source into said tapered

8. An electric apparatus, as claimed in claim 1, said gas supply means including a connector delivering said second gas near the outer region of said tapered portion, whereby said second gas will surround the stream of said first gas as it exits from said tube.