US3052040A

US3052040A - Industrial oven

Info

Publication number: US3052040A
Application number: US819772A
Authority: US
Inventors: Bruno J Falanga; Grenville B Gerrish
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1959-06-11
Filing date: 1959-06-11
Publication date: 1962-09-04
Anticipated expiration: 1979-09-04

Description

P 1962 B. J. FALANGA ETAL 3,052,040

INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 1 Sept. 4, 1962 .B. J. FALANGA ETAL 3,052,040

INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 2 E JF'gL, HNE'H EEE'E' QQ/SH 5 -43 E M/g5 Sept. 4, 1962 B. J. FALANGA ETAL 3,052,040

INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 3 Sept. 4, 1962 B. J. FALANGA ETAL 3,052,040

I INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 4 United 4.

3,052,040 INDUS OVEN Bruno J. Falanga, Lawrence, and Grenville B. Gerrish,

M elrose, Mass; said Falanga assignor to Western Electrrc Company, Incorporated, New York, N .Y., a corporation of New York Filed June 11, 1959, Ser. No. 819,772 2 Claims. (Cl. 34202) This invention relates to ovens, particularly industrial ovens, for heat treating materials at controlled elevated temperatures.

Various materials to be conditioned for use must be subjected to controlled elevated temperatures. When such treatments involve pyrolizing processes, toxic gases may 'be generated presenting the problem of removing the gases from the treating area while maintaining the area at the desired temperature.

The object of the present invention is an oven which, although simple in structure, is highly efiicient in providing a solution to this problem.

In accordance with the object, the invention comprises an oven having a material treating chamber mounted within a heated air circulating system which transfers heat through the chamber Wall to the heat treating area without contaminating the air so that it may be recirculated repeatedly through the heater. A portion of the heated circulating air is diverted to and through the chamber to an exhaust outlet to supply heat directly to the articles being treated and to carry away the toxic or other objectionable gases generated in the process.

In one oven, according to the invention, which is particularly adapted for pyrolizing anodes for tantalum capacitors, the treating chamber is an elongated tubular structure of heat conducting material closed at its ends and provided with a longitudinal opening for admitting articles to be treated. If desired, a cooling jacket may surround this opening to protect portions of the article from the heat of the chamber. A hot air circulating system with rows of inlet and outlet apertures in the treating chamber, as well as in the intermediate chamber which substantially surrounds the treating chamber, causes a continuous flow of hot air around the outside surface of the treating chamber to maintain it at the desired temperature.

Other ducts, connecting the heating chamber with the circulating system and with an exhaust, divert some of the heated air into the chamber where it transfers heat directly to the articles and produces suificient pressure to force out the generated gases. By proper regulation of the heater and control of the proportion of the air recirculated, the oven may be operated at high efliciency by minimizing the heat lost through the exhaust.

Other objects and advantages will be apparent from the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a vertical sectional view of the oven taken near the back of the oven;

FIG. 2 is a vertical sectional view taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of the portion of the oven including the treating chamber and the adjacent structure; and

FIG. 4 is an enlarged fragmentary isometric view of the oven structure.

The oven includes a base 10 supported on rollers 11. A main housing 12 mounted on the base 10 has a blower or fan 14 mounted therein. A shaft 15 of the fan '14 is journalled in suitable bearings 16 and has a pulley 17 mounted on its outer end. A motor 18 mounted on the base 10 has a pulley 19 mounted on its shaft 20 and connected to the pulley 17 by a belt 21. The circulating system, including the fan, has a tubular member 22 extending from an inlet 23 of the fan 14 to a vertical hollow portion 24.

A hollow receptacle 26 disposed in registration with an aperture 27 in the back Wall of the main housing 12, receives suitable filters 28. The aperture 27 is a makeup air inlet for the circulating system, the air passing through the filters 28 and through a tubular passageway 29 into the tubular member 22. The circulating system for the oven also includes a tubular member 31 extending from the outlet end 32 of the fan upwardly and then horizontally at 33 where it connects with a vertical portion 34, aligned with the portion 24, and with a portion 35. The portion 35 is separated for a portion of its length from the portion 33 by a partition 35, at the right end of which the portion 35 joins the portion 33 and the portion 34. The right one-third of the portion 33 and its connection with the vertical portion 34 may be defined as a by-pass 33' for a reason hereinafter described. A damper 36 pivotally supported at 37 is disposed in the horizontal portion 33 at the exit end of the by-pass 33'.

The circulating system and substantially all of the structure within the main housing 12 is surrounded with a suitable insulating material 38. For the purpose of illustration only, FIG. 2 is shown with a portion of this insulating material removed in the area between tubular member 31, extending upwardly from the outlet 32 of the fan, and the recirculating portions 24- and 34 to illustrate in FIG. 2 the contours of the portions and a heating chamber 39 disposed therebetween.

The heating chamber 39 is widened to provide an in terior which, although substantially equal in depth is larger in cross-sectional area than the cross-sectional area of the tubular member 31 to allow the air to remain in the heating chamber a suflicient length of time, or to move therethrough at a greatly reduced rate of speed, to heat the air to the desired temperature, such as a maximum temperature of 1,000 F. The heating chamber 39 may be heated in any suitable manner such as by one or more heating coils 40. Furthermore, the areas or portions 24 and 34 are flared outwardly, respectively, to correspond with the width of the heating chamber 39 to allow the recirculated air to spread out and fill the heating chamber. The portion 24 retards movement of the large body of air leaving the heating unit and starting its next circuit.

With reference to FIG. 1, the arrows illustrate the travel of the heated air upon leaving the fan through a thermal coil 41 into an inlet 42 and out of an outlet 43. The thermal coil 41 is of a commercially known type connected to a variable control unit 44. The inlet 42 is connected to the portion 33 in advance of the damper 36 at the by-pass 33' and the outlet 43 is connected to the portion 35 as shown in FIGS. '1 and 2. The damper 36 disposed at the entrance end of the by-pass 33 controls the percentage of heated air directed through the inlet 42. If the damper is open wide or horizontal, almost all the air will be recirculated through the by-pass 33' with almost none of the air entering the inlet 42, whereas if the damper is closed (vertical) all of the air will be caused to move through the inlet '42. The unit 44 is also of a commercially known type and when set, it is adapted to maintain a predetermined selectively variable temperature in the heating chamber. The thermal coil 41 aiiected by the temperature changes in the vertical member 31 causes the unit 44 to close one or more circuits through the heating coils 40 when the temperature in the system, including the heating chamber, drops below a given value and holds the circuits closed until the temperature returns to the given value. The unit 44 is adjustably set to the desired given temperature. The circuits are represented by a cable 68, portions of which are shown in FIGS. 1 and 2.

The inlet 42 and the outlet 43 are shown in FIG. 3. In this figure it appears that the inlet 42 and the outlet 43- are vertically aligned but they are disposed in staggered relation as illustrated in FIG. 1.

FIGURE 3 illustrates a treating chamber 45 which is of sufficient length as somewhat illustrated in FIG. 4, to receive 32 articles 46 disposed upon leads 47 extending outwardly from their mountings 48 which are carried temporarily by a holder 49. The treating chamber 45 is formed of heat conducting material, such as stainless steel, and is closed at both ends but has a longitudinal opening 50 for receiving the row of spaced articles or material 46 to be treated. An intermediate or circulating chamber 51 surrounds the major portion of the treating chamber 45 and is disposed in between

outer chambers

52 and 53. Walls 54 of the circulating intermediate chamber, formed of simiiar heat conductive material, extend the full length of the treating chamber 45 and the

outer chambers

52 and 53 so as to be closed by the ends which close the treating chamber 45 and

outer chambers

52 and 53.

Longitudinal rows of apertures 55 in the bottom wall 54 of the intermediate chamber 51 serve as inlet ducts for forced air coming into the outer chamber 52 from the inlet 42. Other rows of apertures 56 in the upper wall 54 of the intermediate chamber 51 serve as outlet ducts for the air passing from the circulating intermediate chamber through the outer chamber 53 and through the outlet 43. The inlet ducts 55 and the outlet ducts 56 cause the circulating chamber 51 to be an air passageway which is under the control of the damper 36. The damper 36 is disposed in the system downstream of the inlet 42 and the inlet ducts 55 adjacent the entrance end of the by-pass 33. Therefore, the angular position of the damper 36 controls the flow of heated air through the circulating chamber 51 and about and through the treating chamber 45 via the

apertures

55, 57, and 59.

A row of apertures or bypassing ducts 57 allow a percentage of the heated air to be forced to travel through a vertical passageway or feeding line 58 and through spaced rows of inlet ducts 59 to enter the treating chamber 45. The inlet ducts 59 are staggered or disposed in two rows, as illustrated in FIG. 4, but both rows are positioned back of a baflie-plate 60 so that all air entering the treating chamber will be directed away from the article or material46. Rows of exhaust or outlet ducts 61, which are larger than the inlet ducts 59, permit air and gases mixed therewith to pass from the treating chamber 45 through an exhaust line 62. The inlet ducts 59, in the present instance, are substantially one-half the diameter of the outlet ducts 61.

A cooling jacket or shield 63 has an elongated aperture 64 therein through which the articles 46 on their leads 47 and their supports 48 may extend, to protect the supports against the heat of the treating chamber and cool the air escaping from the treating chamber. The

holder 49 with the supports 48 therein closes the opening 50. The cooling jacket 63 is hollow as at 65 for the circulation of coolant such as water through an inlet 66 from a supply, not shown, through the cooling jacket 63 and through an outlet 67 back to the supply.

Operation The oven may be readied for operation in advance of the insertion of the material or articles to be treated by energizing the heating coils 40 to bring the temperature in the heating unit 39 to that desired. The unit 44 is set to maintain the temperature in advance of the treating chamber 45 at a given level. The motor 18 may be energized and the group of articles 46 in their holder 49 may be inserted in the oven to locate the portions to be treated in the treating chamber 45.

The articles will remain in the heating chamber a predetermined length of time during which there is a continuous recirculation of air at a predetermined elevated temperature through the oven. A predetermined portion of this circulating air is directed into the treating chamber in a path directed away from the articles but caused to fill the treating chamber to cause an internal heating of the chamber through a continuous passing of air through the chamber.

An important purpose of this small percentage of the total air, circulated and recirculated, which in the present instance is 30%, is to remove gases resulting from the treatment of the materials from the treating chamber. At the same time, the major portion of the heated air is recirculated in such a manner that it is caused to flow about the heat conducting material of the treating chamber, applying an external heat to the treating chamber constantly to retain the predetermined temperature within the treating chamber. The recirculated portion, or in the present instance, the 70% of the heated air is recirculated through the heating unit where it is reheated, for example, to a temperature in excess of that required for the treating chamber, so that the pulling in of an additional 30% of air at room temperature through the filters 28 and mixed with the super heated recirculating air, will result in air flowing into and around the treating chamber at a temperature desired for treating the material or articles 46.

The temperature of the air is controlled through the unit 44 and the percentage of recirculation of the air is controlled partially through the sizes of the apertures 59 and 61 and also by the damper 36.

It is to be understood that the above described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. An oven for heat treating a material, carried by a support of a given size which material expels a gas when subjected to a predetermined temperature comprising a treating chamber substantially circular in crosssection and having a material receiving opening adapted to be closed by the support for the material, the treating chamber being formed of heat conducting material and having an inlet duct adjacent one side of the opening and an outlet duct 'adjacent the opposing side of the opening, an air circulating system including a circulating chamber defining an air passage partially surrounding the treating chamber and having inlet and outlet openings disposed at opposing sides of the treating chamber so that heated air passing through the circulating chamber from the inlet to the outlet openings will have to move about and externally heat the treating chamber, a feeding line open to the inlet duot, an exhaust line open from the outlet duct to the atmosphere, a by-passing duct connected to the feeding line to direct 'a given percentage of the heated air through the inlet duct into and through the treating chamber to internally heat the treating chamber and cause exhausting of gases expelled from the material to pass through the outlet duct and the exhaust line, an air heating unit in the air circulating system to heat the air therein to a predetermined elevated temperature, and means to cause the heated air to flow continuously through the system with :a given percentage of the heated air to flow through the circulating chamber to externally heat the treating chamber and the remaining percentage of the heated air to flow through the by passing duct.

2. An even according to claim 1 in which a bafile is mounted adjacent the opening in the treating chamber and extends between the inlet duct and the material to deflect the heated air away from the material and cause it to circulate through the treating chamber in a path away from :the material to the outlet duct.

References Cited in the file of this patent UNITED STATES PATENTS 1,902,575 Nichols Mar. 21, 1933 2,029,117 Otis Jan. 28, 1936 2,365,890 McBean Dec. 26, 1944 2,627,838 Huggins Feb. 10, 1953 FOREIGN PATENTS 461,813 Italy Feb. 15, 1951 1,063,054 France Apr. 29, 1954