US1823629A - Process of annealing - Google Patents

Description

Sept. 15, 1931.

H. ROBERTSON PROCESS OF ANNEALING 22. 1927 3 Sheets-Sheet 2 Original Filed Oct.

fie. 5.

Sept. 15, 1931. H. M. ROBERTSON PROCESS OF ANNEALING 3 t w n 0 S a 6 h S n. 3 1 7 2 9 l a 2 C 0 d a e an 1, 1 F l a n i E .n o J I v 21 I MN hm W;

Patented Sept. 15, 1931 PATENT OFFICE HARRY M. ROBERTSON, OF CLEVELAND, OHIO PROCESS OF ANNEALING Original application filed October 22, 1927, Serial No. 228,082. Divided and this application filed January 31, 1930.

This invention relates to a process of heat treating or annealing bodies or castings, such as malleable iron castings and the like.

One object of the invention is to provide an improved process of annealing, whereby castings may be annealed in a relatively short period of time.

Another object of the invention is to provide an improved process of annealing in a nonoxidizing atmosphere.

Other objects of the invention will be apparent to those skilled in the art to which my invention relates from the following description taken in connection with the accom- 5 panying drawings, which show one apparatus capable of carrying out the steps of my process.

Fig. 1 is a top plan view of the apparatus, such View showing two apparatuses arranged side by side. 7

Fig. 2 is a side elevation.

Fig. 3 is a front elevation.

Fig. 4 is a section (enlarged) on the line 4-4 of Fig. 2.

Fig. 5 is a section on the line 5-5 of Fig. 4.

Fig. 6 is a section onthe line 6-6 of Fig. 4.

ln the drawings, 1 indicates a suitable bed of concrete having insulating coverings 2, 3, of suitable fire-resisting materials, the latter forming the flooring for the oven or chamber 4. In the accompanying drawings I have shown two chambers 4 arranged side by side upon a single bed 1, such arrangement being preferable since a single exhaust means or chimney (to be later referred to) may be utilized for both chambers and thus reduce the cost of installation.

Each chamber 4 is formed by an end wall 5 and side walls 6, 6a, each formed of suitable fire-resisting material or materials, such as fire brick 6 and an outer wall of brick 7 formed of suitable material such as diatomaceous earth. The inner side walls 6a of the two chambers are separated by a suitable insulation 8 which permits of expansion of these walls. Extending from the end wall 5, at an elevation above the bed 1, is a base 9 supported at its outer end by suitable uprights 10. The base 9 may comprise longitudinal and transverse channels or the like,

Serial No. 424,871.

other suitable material. The bed 11 co-operates with extended portions 60: of the side walls 6, 6a, to form a fire chamber 12. Each of the annealing chambers 4 and its fire chamber 12 are covered by a top or roof of fire brick 13 which'is covered with a suitable insulation, such as diatomaceous earth powder. The side walls 6m and top of the fire chamber preferably converge, and at their outer portions these walls and the bed 11 form. an opening 14 for a burner or other suitable means for supplying and efl'ecting combustion of fuel, for example, powdered coal supplied under pressure in any well known manner. That end of the chamber 4 opposite to the fire chamber 12 is open, as shown at 15, to permit the pots containing the castings to be annealed to be moved into the chamber 4-and removed therefrom by suitable apparatus, such as trucks. The opening 15 is closed by a door or wall 16 and the latter sealed when the apparatus is set in operation.

17 indicates a main flue formed in the upper portion of each side wall 6, 6a, and extending longitudinally thereof, and substantially from end to end of said wall, the side wall being thickened and extended upwardly above the top 13 to provide for the flue 17. 18 indicates flues formed in each of the side Walls 6,- 6a, connected at their upper ends with the adjacent main flue and leading downwardly (preferably vertically) to or below the flooring 3 and each connected with one or more exhaust ports 19, 19a, formed in and leading through the side walls adjacent the flooring 3. I preferably provide a pair of inlets or ports 19, 19a for each flue 18. The vertical flues 18 adjacent to the opening 15 are connected at their lower ends by a transverse flue 20 formed in the flooring 3 and bed 1, the top wall of this flue comprising a grating 1a of suitable construction disposed in the plane of the flooring 3, whereby any air which may leak into the chamber along the lower portion ofthe opening 15 may flow through the grating into the collecting flue 20 and be exhausted through the flues 18, 17 the grating permitting the air to flow through it and also providing a suitable wall or flooring for the trucks or other apparatus to run over. By the provision of this flue at that end of the chamber 4 remote from the heating means it insures a suflicient supply of the hot gases to this portion of the chamber 4. The pairs of exhaust ports 19, 19a, connected with the flues 18 are spaced from each other preferably uniformly from end to end of the chamber 4.

As shown in Fig. 5, the upper ends of the vertical flues 18 are slightly smaller in width than the width of the flues 17. This permits the bottom of each flue 17 at opposite sides of the adjacent fine 18 to form a seat for a valve or damper 18, preferably comprising a relatively heavy plate which may be raised and lowered to close or open to any desired extent the adjacent flue 18, and thus control the exhaust of the products of combustion therethrough. The dampers 18 are operated in a manner to be later set forth. One end of each flue 17 (preferably that end adjacent the fire chamber 12) is extended upwardly, as shown at 21 and the latter is connected to a manifold 22 disposed transversely of and mounted on the top 13. The manifold may be suitably insulated on its inner surface to protect its metal shell. As shown, I provide one manifold 22 for the flues 1717, l7l7, formed in the side walls 6, 6a, for both chambers. The manifold 22 is connected by conduits 23, 23a, with a main conduit 24, which in turn is connected with the inlet of a suitable suction or exhaust mechanism 25, preferably comprising a casing and a fan mounted therein. The fan is connected to the shaft of a motor 26 and driven thereby to provide a forced draft to exhaust the products of combustion and gases from the chambers 4. The suction mechanism 25 and motor 26 are mounted on a suitable support 27 carried by an upright 28.

The outlet from the casing of the suction mechanism 25 is connected by a conduit 29 with a chimney or stack 30 through which the products of combustion drawn from the chamber or chambers 4 are forced and discharged into the atmosphere.

The top 13 is formed with one or more inlet openings 31, and these inlets have connected to them, supply flues 32, connected through a common supply flue 33 to the stack or chimney 30.

34 indicates a valve or slide damper arranged to control the flow of the products of combustion and heat through the conduit 24 under the influence of the suction fan.

35 indicates a valve or damper mounted in the stack 30 above the connection of the supply flue 33 therewith and 36 indicates a valve or damper mounted in the fine 33. The dampers 35 and 36 are preferably independently operated. In one method of operation the damper 36 is closed and the damper 3:) opened, so that the products of combustion tsaaeae and gases may be discharged into and through the stack 30; but when desired, for reasons to be later set forth, the damper 35 is closed and the damper 36 opened, in which event the products of combustion are returned under pressure to the chamber l to effect a nonoxidizing condition therein.

The dampers 18 may be operated by any desired means; but preferably each damper 18' has connected to it one end of a flexible member, such as a chain 37. The chain 3 leads upwardly through an opening in the top wall of the adjacent conduit 17 and leads over a sheave 38, then around a second sheave 39; from the-latter sheave the chain leads downwardly and around a third sheave 40 and then horizontally to an operating station at some convenient point, for example, one end of the a paratus (preferably that end adjacent the lire chamber); all of the chains for controlling the dampers for each chamber 4 leading to one operatingstation. At the operating station means are provided for securing each chain and iii-one of several predetermined positions, so that the damper connected to it may be closed, or held in full open position or a partially open position. By preference the dampers are heavy and therefore self closing under the influence of gravity, so that pull on any chain will lift the damper connected to its inner end to the desired position. The free end of the chain is connected to a bar or rod 41 preferably terminating in a handle and slides endwise through an opening 42 formed in a plate 43 suitably connected to the walls of the apparatus. The rod 41 is provided with a series of teeth or lugs one of which engages the face of the plate 42 to hold the rod a]. at any position to which it is pulled or slid, to raise the adjacent damper. By swinging the rod 41 in its guide opening 42, it may be released from the plate and allowed to slide inwardly due to the weight of the' adjacent damper when it is desired to close the latter. Each damper 18 may be raised and lowered any desired distance and by their control or adjustment the influence of the exhaust mechanism 25 is effective to insure adequate circulation of the products of combustion throughout the annealing during each annealing operation. I

In carrying out my process, either or both chambers are first charged with pots tilled with the castings to be annealed, the chamber closed and sealed, the damper 36 closed and the dampers 3d and 35 moved to full open position, and dampers 18' opened to the desired extent. Next the heating means are then ignited'and the motor 26 started to drive the exhaust fan. Since the inlet of the casing surrounding the fan is connected through the conduits 24, 23, 23a and manifold 22 with the fines 2l1718 and the latter ha e inlet openings or ports 1919a,

bodies.

leading from the annealing chamber 4, the products of combustion will be drawn or sucked through these ports and discharged from the fan casing through the stack to the outside atmosphere. In this etc of my process the temperature of the chamber 4 is raised to approximately 1600 or 1650 degrees F. (depending on the nature of the bodies being treated). Next, the supply of fuel is Feduced suificiently and the damper 3,4 partially closed to reduce the suction effect and rate of exhaust of the products of combustion to produce and maintain a soaking temperature within and throughout all portions of the chamber during the period required to effect annealing. Next, the supply of fuel to the heating means is reduced or cut-ofi' so as to effect a relatively slow cooling; finally the damper 34 is fully open and supply of fuel cut off (if not already cut off) to permit of rapid cooling of'the chamber' and In accordance with my improved process, and the preferred form of construction for carrying out the process, the exhaust ports are disposed at the lowest and most remote portions of the annealing chamber 4, that is, adjacent its flooring and at substantially uniformly spaced points along its opposite sides and across the fioor adjacent the receiving opening 15 at the farthest and lowest point from the heating means. In this form of construction, the products of combustion are caused to circulate to all portions as well as the lowestportion of the chamber and substantially uniformly over its entire area, with the result that heat is applied to and over and around all of the filled pots. In the use of my improved apparatus and the carrying out of the process therewith, I have been able to reduce the total period of time required for heating the chamber up to the desired degree of temperature (to-wit, substantially 1600 or 1650 degrees, F.) and the time required for treating or annealing the castings is reduced also materially as compared to apparatus of this character of which I have knowledge. By reducing the total period the apparatus is in use for'each charglng, a great saving of fuel results and the apparatus can be recharged and operated a great number of times in any predetermined period which has the effect of increasing the capacity for any given installation. It will be noted that in the use of my improved apparatus, since the circulation of the products of combustion is ef- .fected by a power operated suction or exhaust mechanism, the chamber 4 may be enlarged to increase the capacity without increasing the size of the fire chamber, which tends to reduce the cost of operation.

When it is desired to produce a non-oxidizi ing atmosphere in the chamber, I prevent air or oxygen or any substantial amount thereof from coming into contact with the pots .products of combustion into the upper porduring the period the chamber is being heated and during the period of annealing. To carry out these steps in this manner, I return the products of combustion, under pressure to the chamber 4, preferably at a level above theoutlet ports. This form of my method iseffected by adjusting the dampers 35, 36, as already set forth, so that the products will be forced through the supply fiues 33, and 32 and inlets 31 to the chamber4. In this latter method, deterioration of the pots is reduced or substantially eliminated and hence permits them to be mantained in use for an indefinite period. This application is a division of my application Ser. No. 228,- 082, Letters Patent N 0. 1,7 52,697, dated April 1, 1930.

To those skilled in the art to which my invention relates many changes in construction and widely differing embodimentsand applications of the invention will suggest themselves without departing from its spirit and I scope. My disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

What I claim is:

1. The herein disclosed process of annealing which consists in charging a chamber with filled pots, then in supplying heat and tion of said chamber and simultaneously exhausting the products of combustion from the lower portion of said chamber at a plurality of points disposed adjacent the bottom portion of said chamber and returning said products of combustion to and discharging them directly into the upper portion of said chamber. a

2. The herein disclosed process of annealing which consists in supplying heat to a charged chamber and simultaneously exhausting the products of combustion from the lower portions of the chamber at a plurality of. points by forced draft to raise the temperature of the chamber to the desired degree and conducting the products to and discharging them into the upper portion of the chamber to produce a non-oxidizing atmosphere therein, then in reducing the heat supply to the chamber and rate of exhaust therefrom to produce suitable soaking conditions in the chamber, and then slowly cooling the chamber.

In testimony whereof, I have hereunto subscribed my name.

Images