US3035819A - Brazing or heat treating furnace - Google Patents

Description

y 1962 H. E. MESCHER ETAL 3,035,819

BRAZING OR HEAT TREATING FURNACE 4 Sheets-Sheet 1 Filed June 5, 1961 INVENTORS HAROLD E. MESCHER WALTER E. HEYER y 2, 1962 H. E. MESCHER EIAL 3,035,819

BRAZING OR HEAT TREATING FURNACE Filed June 5, 1961 4 Sheets-Sheet INVENTORS HAROLD E MESCHER WALTERE.HEYER BY #W W' ATTORNEY y 1962 H. E. MESCHER ETAL 3,035,819

BRAZING OR HEAT TREATING FURNACE Filed June 5, 1961 4 Sheets-Sheet 3 FIG.3 I5

INVENTORS HAROLD E. MESCHER WALTER E. HEYER ATTORNEY May 22, 1962 H E. MESCHER ETAL 3,035,819

BRAZING OR HEAT TREATING FURNACE Filed June 5, 1961 4 Sheets-Sheet 4 1 ill! I I I i t 1 2O HAROLD E. MESCHER WALTER E. HEYER A TORNEY United States Patent Ghtice 3,335,319 Patented May 22, 1962 3,035,319 BRAZING OR HEAT TREATING FURNACE Harold E. Mescher, Los Angeles County, and Walter E.

Heyer, Orange County, Calif., assignors to Pacific Scientific Company, Los Angeles, Calif., a corporation of California Filed June 5, 1961, Ser. No. 114,782 7 Claims. (Cl. 257-303) This invention relates generally to furnaces for brazing and/ or heat treating work and equipment, such as rocket motors, and the invention has reference more particularly to a novel furnace of the above character especially suitable for reliably brazing complicated equipment quickly and with great case.

One object of the present invention is to provide a novel furnace of the above character that employs a common base for both heating and cooling, such base being stationary and not requiring any handling of the work in passing from the heating to the cooling cycles.

Another object of the present invention is to provide a novel furnace of the above character so constructed and designed as to facilitate the convenient and rapid heating of Work or equipment to be brazed or heat treated, the maintenance of a desired operating temperature, and the rapid cooling of the treated equipment or work after the heating cycle is over, without the necessity of moving the work or equipment treated at any time during the complete cycle of operation.

Another object of the present invention is to provide a novel furnace of the above character that employs relatively movable mating shells or sections for effecting the heating and cooling of the equipment or work being treated.

A feature of the present invention is the provision of heating shells having unique low heat storage insulating wall surfaces for rapidly rising to and maintaining the desired temperature within the furnace during treatment and employing uniformly distributed effective flat-plane heaters for facilitating rapid heating of the same in use.

Another feature of the present invention is the provision of mating cooling shells or sections having cold walls which rapidly absorb heat due to radiation and high temperature differentials, the cold walls also absorbing great heat due to convection through the use of large air flow passing therewithin.

Still another feature of the present invention is the provision of novel sealing and locking means whereby, when the heating sections or shells are closed, the combustion within the shells can be controlled at will with- FIG. 1 is a perspective view of the novel furnace of this invention shown in open position and with treated equipment, such as a rocket motor enclosed Within a sealed retort about to be removed from the same;

FIG. 1A is a fragmentary view of a portion of the structure of FIG. 1 showing the sealing of the lower portion of a heating chamber section;

FIG. 2 is a view in side elevation of the cooling chamber with its shells in closed and locked position;

FIG. 3 is a view, similar to FIG. 2, of the heating chamber, showing its two shells or sections in closed, locked position;

PEG. 4- is an enlarged fragmentary view illustrating one form of the sealing and locking mechanism of the heating chamber;

FIG. 5 is a view taken along line 55 of FIG. 4 looking in the direction of the arrows;

FIG. 6 is a sectional view taken along the line 66 of P16. 5 looking in the direction of the arrows; and

FIG. 7 is a fragmentary view illustrating a modified form of sealing means.

Similar characters of reference are used in the above figures to designate corresponding parts.

Referring now to the drawings, reference numeral 1 designates a stationary platform or base having the form of a grating of the novel furnace of this invention, upon which base is adapted to be placed a closed retort 2 containing work such as a rocket motor to be brazed or heat treated. In the drawings, the furnace is illustrated as receiving retort 2 which is of large size since the furnace is capable of being made in almost any size desired. Mounted upon a floor 1' are pairs of tracks 3 and 4 which are shown crossing each other at right angles, and the base or work area 1 is common or at the intersection of both pairs of tracks. Mounted upon the tracks 3 for movement therealong are wheeled carriages 5 and 5', the said carriages carrying similar and opposed complementary heating chamber sections or shells 6 and 6'. These sections 6 and 6, mounted upon the carriages 5 and 5, are adapted to traverse the tracks 3 so as to move toward or away from each other by means of electric motor drives 7 and 7, which drives are controlled in operation from a console 8 used in conjunction with control panel 9 under the control of an operator 10 who is sufficiently removed from the furnace to be protected from the great heat thereof, but, nevertheless, can see fully the operation of the furnace.

The shells or sections 6 and 6' are shown as of substantially semi-cylindrical shape and comprise metal exterior side and top walls having an interior lining 11 of lightweight, highly refractory insulating material that has an extremely low heat absorption coefficient, and hence is highly effective even though used in a relatively thin light layer: a suitable material for this purpose being Fiberfrax, a product of the Carborundum Company. This lightweight insulating material covers the inner side and top walls of sections 6 and 6. Distributed throughout the inner semi-cylindrical side wall surfaces of each of the heating sections 6 are flat-flame, high-heat release gas burners or heating elements 12, the distribution of these elements being such that, as illustrated in the figures, a substantially complete envelope of heat is provided all over the inner cylindrical wall surface of the heating chamber when the sections 6, 6' are brought together, as shown in FIG. 3, while in use. These uniformly distributed burners, acting in conjunction with the low heat storage refractory 11, produce an enclosure in use of almost uniform radiant heat release whereby the hot face of the high insulating low heat storage material 11 follows the heat source in temperature very closely and, in doing so, becomes a secondary source of heat by reradiating the heat from the base source inwardly toward the retort 2, effectively heating uniformly and rapidly all portions of the work contained therewithin, enabling the furnace to have a rapid heating cycle in use.

The side edges of the heating sections 6 and 6' are shown provided with I-beams 13 and 13' attached thereto and extending vertically, the beams 13 of shell 6 opposing the beams 13' of shell 6' when these shells are brought together. Attached to the opposed faces of the I-beams are shown strips of sealing material, such as treated asbestos 14 and 14', which strips abut each other in sealing relation when the shells are brought together in use, thereby preventing the escape of hot exhaust gases from the heating chamber and allowing the heating chamher to have a readily controlled temperature. In those bustion from the heating chamber.

sections 6 and 6' are brought together preparatory to a instances where the heating chamber is of large size this form of sealing means shown in FIG. 7 is preferred. In this form of the invention the sealing strips 36, as of graphited asbestos engaging one of the I-beams such as 13', are carried by leaf springs 37 mounted on the other I-beam, such as 13, which springs act to urge the strips 36 into uniform contact with the beam 13 all along its length, regardless of any distortion of this I-beam. Plates 39 cover adjoining portions of adjacent longitudinally arranged springs 37 to prevent the escape of hot gases from between adjacent springs 37.

The retort 2 is shown supported above base 1 by means of struts 35 so that furnace heat can pass readily under the retort 2 for uniform heating in use, as will further appear. A controlled atmosphere of desired pressure,

. such as argon, nitrogen and hydrogen, in any sequence desired can be maintained within closed retort 2 as by use of gas feed pipes 37 entering the bottom of this retort (see FIG. 1A).

The top walls 15 and 15' of the casing 6 and 6' are shown provided with complementary flue openings 16 and 16' to enable the regulated escape of the products of combustion. Also, flues 38 connect with the lower portions of the heating chamber sections 6 and 6' to allow the regulated escape of combustion products in use.

Mounted on the I-beams 13 in mutually vertically spaced relation are a series of pneumatic cylinders 17 (see also FIG. 4) which have piston movable plungers 18 projecting therefrom, the outer ends of which plungers are enlarged to form cylindrical locking heads 19 having outer tapered portions 20. The heads 19 are adapted I 21 have lower reduced portions 24, the peripheries of which are adapted to engage the undersurface of heads A 19 when the slide bars 22 are moved upwardly by means of rods 25 driven by pistons within pneumatic cylinders 26 mounted on heating section 6'.

Thus, when the two shells 6 and 6' are initially brought together, the rods 25 will hold the slide bars 22 in their lower positions, as shown in FIG. 5, so that the locking heads 19 will pass through apertures 21. Thereafter, the cylinders 26 are excited to force rods 25 upwardly, and hence slide bars 22 upwardly, to cause the narrow portions 24 of apertures 21 to engage behind the locking heads 19. The cylinders 17 can then be energized to hold the heads 19 firmly against the slide bars 22 to firmly compress the sealing material 14 and 14' between I- beams 13 and 13', or in the case of FIG. 7, to hold the sealing material 36 firmly against I-beam 13', thereby tightly sealing the two sections or shells 6 together and preventing the undesired escape of the products of corn- After the heating 7 pending knife blades for engaging in the sand seals and 41. Thus, gases of combustion cannot escape around the periphery of the base 1, so that a desired temperature can be maintained within the combustion chamber in use.

Thus, with the heating sections closed, the retort 2 and its contained work can be raised in a very short time to a brazing temperature through use of the effective flatflame burners 12 which surround the retort. In practice, a rocket motor weighing approximately six tons and standing many feet high can be brought up to brazing temperature in one hour in a desired atmosphere, brazed for a period of thirty minutes and cooled to 400 F. within a short time thereafter, so that the entire heating cycle of a large piece of work of this nature takes but a short time. Since the atmosphere within the retort 2 can be closely controlled and no oxidation takes place, the parts remain bright and clean brazing takes place. The same highly efiicient operation can take place if a heat treatment operation is desired.

The cooling is effected by moving the shells 6 and 6 apart from each other through operation of the motors 7 and 7 from the console 8, and the cooling shells or sections 28 and 28' are brought together into closed position as shown in FIG. 2. These cooling sections are also shown of semi-cylindrical shape but open at their upper and lower ends so that air can be driven upwardly through the same, as by means of a blower 29 located beneath the base (see FIG. 3). The cooling shells 28 and 28' are also supported upon movable carriages 30 and 36' similar to carriages 5 and 5, the carriages 3i} and 3t) riding on track 4. The shells 28 and 2.8 have water supply lines 34, 34 for supplying cooling water to water conducting spray tubes 33 and 33' at their upper ends for spraying cooling water on the outer wall surfaces of these shells so that in use the cooling water sprayed on the walls of shells 28 and 28 together with the air blast from blower 29 and auxiliary blowers 31 mounted on the carriages 30 and 30' produces a terrific swirling of air within the closed cooling chamber sections, resulting in rapid cooling of the retort and the work therein. This rapid cooling is desirable in order to initially set the braze rapidly and to quickly pass through the critical range of alloys used so as to prevent weld cracks, and it must be borne in mind that the cold wall chamber sections 28 and 28 readily absorb heat radiated from the work and carry this heat away through the circulating water. Rapid circulation of air within the cooling sections or shells 28 and 28' in use also effects rapid cooling. These shells may be held together when the cooling chambers are being used by use of pneumatic cylinders 17 and locking heads 19 as described in connection with the heating chamber sections.

After the cooling cycle is over, the sections 28 and 28' can be readily moved apart through operation of motors 32 and 32 from console 8, whereupon the work can be lifted away as by use of a crane preparatory to the insertion of new work into the furnace.

Thus, it will be seen that the novel furnace of the present invention provides for the rapid, efiicient heating of the work, the maintenance of uniform temperature within the heating chamber 6, 6' and controlled atmosphere within the retort 2, obtaining uniform brazing or heat treating as the case may be, the quick separation of the two sections or casing halves 6 and 6' upon the completion of the heating cycle, the rapid closure of the cooling sections 28 and 28', and then the tremendously rapid cooling afforded by the chilled wall areas of these casings and by the tremendous blast of air which circulates within the same during the cooling cycle. Thus, the novel furnace of the present invention provides an exceedingly efficient cycle of operations enabling a rapid cycle with thorough heat treatment or brazing of work of any size and eliminating any handling of the work during the entire cycle of operations, resulting in a uniform product. Since all operations take place by remote control from the console 8, injury to personnel in operating the furnace is eliminated.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A furnace of the character described comprising a stationary base for receiving a retort containing work to be treated, pairs of tracks intersecting at the periphery of said base, complementary carriage-supported heating chamber sections movable over one pair of said tracks, motor means for moving said heating chamber sections toward each other to enclose the work upon said base, heating elements carried by said heating chamber sections for effecting the heating of the retort and contained work to the desired temperature within said closed sections and the maintenance of the work at such temperature until the work has been treated, said motor means serving to move said heating chamber sections away from each other and from the Work after the heating operation, complementary carriage-supported cooling chamber sections movable over another pair of said tracks, additional motor means for moving said cooling chamber sections toward each other to enclose the work after the operating cycle to quickly cool the same, said additional motor means serving to move said cooling chamber sections away from each other and away from the Work after the cooling operation, whereupon the work may be removed from said base.

2. A furnace as defined in claim 1 wherein said heating chamber sections are interiorly covered with a lightweight, highly insulating, low-heat absorbing lining, said heating elements comprising flat-plane burners distributed over the interior surfaces of said heating chamber sections and acting to substantially uniformly heat said lining, whereby the latter acts as a radiant heater to effectively and uniformly heat the retort and contained work.

3. A furnace as defined in claim 2 wherein said heating chamber sections are of substantially semi-cylindrical shape and are provided with sealing material at their meeting edges whereby the products of combustion are prevented from escaping from said sections when they are in closed abutting position.

4. A furnace as defined in claim 3 wherein leaf springs are provided along the meeting edges of said heating chamber sections for pressing the sealing material uniformly against at least one of said sections to obtain a tight seal.

5. A furnace as defined in claim 3 wherein remotely controlled locking means are provided for locking said heating chamber sections together when in closed position.

6. A furnace as defined in claim 1 wherein said cooling chamber sections are of substantially semi-cylindrical shape and are water-cooled to provide an effective radiant heat sink, and means for circulating cooling fluid within said closed cooling chamber sections and outwardly thereof to effect rapid convection cooling of the work.

7. A furnace having cruciform tracks enclosing a heating area adapted to receive work to be treated, complementary heat insulated heating shells movable over one of said tracks for enclosing the work, heating elements within said shells to quickly heat the work to the desired operating temperature and to maintain the same at such temperature during the heating operation, and complementary cooling shells movable over the other of said tracks for enclosing the work, said cooling shells having cooling fluid circulating over the walls thereof, and throughout the interior thereof to absorb heat from the Work by convection and radiant absorption, to thereby rapidly cool the work whereupon said cooling shells are movable apart to allow the work to be removed.

Albert Oct. 28, 1952 Grunewald et a1. Oct. 25, 1955

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