US1971666A

US1971666A - Apparatus for heat treating strip metal

Info

Publication number: US1971666A
Application number: US625570A
Authority: US
Inventors: William R Webster
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-07-29
Filing date: 1932-07-29
Publication date: 1934-08-28
Anticipated expiration: 1951-08-28

Description

Aug. 28, 1934- w. R. WEBSTER \PPARATUS FOR'HEAT TREATING STRIP METAL Filed July 29, 1932 2 Sheets-Sheet l Aug. 28, 192.4. R;WEB T ER 1,971,666

APPARATUS FOR HEAT TREATING STRIP METAL Filed July 29, 1952 2 Sheets-Sheet 2 Patented Aug. 28 1934 PATENT OFFICE.

APPARATUS FOR HEAT TREATING STRIP METAL William R. Webster, Bridgeport, Conn.

Application July 29, 1932, Serial No. 625,570

17 Claims. (01. 263 -3) This invention relates to an apparatus forheat treating metal, and more particularly for heating metal in strip form for annealing and similar purposes.

In the art of making brass and other cold rolled metal in strips, it is necessary that the strip be heated at intermediate stages and also as a final operation for the purpose of annealing it. In order to meet the requirements of the trade, it is essential that the metal be heated within very close temperature ranges in order to give it the required properties.

. mately 100 pounds. According to present practice,

such coils are placed on a sheet, of steel approxi-.

mately 5 feet wide by 12 feet long, and these sheets are positioned upon the hearth of a furnace, the interior of which is heated by oil, gas, coal or electricity. It is intended to maintain the temperature of the furnace chamber at such a ,7 point .that the strip will be given the desired properties, but it is extremely difficult to achieve a satisfactory result by this practice. Forone thing, it is a matter of great difficulty or practically impossible to so distribute the heat that the coils will attain the required temperature throughout their bodies. This is particularly true if certain of the coils are of different dimensions from others, as frequently happens. Moreover, present practice calls for a heavier coil than the heretofore standard 100 pound coil, and the size of the coil would be much increased if it were possibleto solve the annealing problem, but it is impossible to handle large coils in a satisfactory way in the annealing furnaces such as now commonly used.

One of the objects of my invention is to overcome the above-mentioned disadvantages.

Another object of my invention is to provide I a method by which all portions of a metal strip can be uniformly heated in a convenient manner tory form of apparatus for carrying out the annealing of strip metal.

To these and other ends, the invention consists in the novel features and steps hereinafter described and claimed.

In the accompanying drawings:

Fig. 1 is a side elevation of annealing apparatus constructed in accordance with my invention;

Fig. 2 is a top plan view of the apparatus shown in Fig. 1;

Figs. 3, 4 and 5 are detail views showing means for regulating the heating of the drum about which the strip passes;

Fig. 6 is a diagrammatic view of form of heating apparatus;

Fig. 7 is a somewhat diagrammatic view of a device for adjusting a burner nozzle laterally relatively to the heating drum;

Fig. '7 is a further fragmentary view of certain parts shown in Fig. 7 and Fig. 8 is a view of the heating drum.

In the practice of my improved method, I heat the strip to a uniform temperature by heating the wall of a rotary drum about the periphery of which the strip is passed, so that the strip lies in contact with'the heated surface of the drum and moves along with it as the drum is revolved. The drum is heated from the inside and the heat passes from its inner surface to its exterior surface and by controlling the temperature of the exterior surface, with which thestrip contacts, and the speed at which the strip travels through its path or orbit, it is possible to obtain a nicer control of the metal temperature than has been possible heretofore, and it is also possible to heat all portions of the strip uniformly and in a manner which is convenient for the operator.

Referring particularly to Figs. 1 and 2 of the drawings,- A is acylindrical drum of heat-resisting material such as nichrome which has a flanged portion B at one side by means of which it is mounted on a shaft C, the shaft being fixed to the drum and adapted to rotate on suitable bearings D, D, which are preferably of the ball or roller type. Supported in the interior of the drum is a burner H. This burner may be of a modified "any suitable kind, but in the present instance it may be assumed that it is a gas burner supplied with gas and air through pipes L and K, respectively. Closely contiguous to the drum A are two rollers E and E, respectively, which are arranged close together and whose axes are parallel to that of drum A. The coil of metal N to be annealed is mounted on a suitable support 0, and the strip from the coil is passed around the roller E, thence around the drum A, and thence around the roller E, from which it passes to a pair of pinch rolls F driven by a variable speed motor G which is preferably an electric motor. From the pinch rolls F the strip passes to a winding device or blocker I which is preferably driven by an electric motor J.

The burner in the drum presents a plurality of corner nozzles directed axially of the drum and. located near its circumference at a number of points. Four of such nozzles are shown in the present instance. It is, of course, understood that this burner structure is stationary, and that the drum A having the thin cylindrical wallabout which the strip is passed rotates about the burner structure, and that the burner structure by send ing flames outward against or into close proximity to the inner circumferenceof the cylindrical strip-contacting wall, heats said wall to a uniform degree throughout the periphery of the drum.

By controlling the temperature of the exterior surface of the drum and the speed at which the pinch rolls or pulling rolls F are driven (and by means of which the drum is rotated), the temperature of the metal can be maintained within very close limits, and the softness of the metal as measured by the crystal size thereof controlled within exceedingly close limits, which is a highly desirable result in this art. After having been placed in position about the drum in the manner shown in Fig. 1, and after initiating the drive of pinch rolls F and the drive of the blocker I at a suitable slow speed, the strip can be passed over a large part of the round hollow heating structure, preferably with the strip pulling along the drum so that a given point on the strip surface maintains contact with a given point on the drum surface until the strip portion in question passes to roll E. In a specific instance, the drum having been heated so that its exterior surface was at a temperaturev of approximately 750 0., a strip of metal .015 inches thick was traversed through the apparatus at the rate of 4.4; feet per minute, the diameter of the drum being substantially 12 inches and the arrangement of the rolls E, E being substantially as shown in Fig. 1, with the result that a crystal diameter of .066 millimeters was obtained. Other conditions being the same but the speed being increased to 10.7 feet per minute, a crystal diameter of .044 millimeters was obtained. At 22.5 feet per minute a crystal size of .030 millimeters was obtained, and at 47 feet per'minute a crystal size of .019 millimeters.

It is a very convenient practice to maintain the exterior surface of the drum at a constant temperature and vary the speed of the strip in order to vary the size of the crystals or in order to vary the amount of heat imparted to the strip. By proceedings as above described, the speed of the strip is made the only variable factor and this can be nicely controlled to give the desired results. I

In order to maintain a uniform degree of contact between the strip and the surface of the drum, a tension device Q of any well-known form is employed which is capable of being adjusted by means of a screw or wedge (not shown); so that the precise degree of tension applied by the pinch rolls F can be maintained. Strip metal of the character in question sometimes contains a certain amount of oil, the burnt products of which are apt to build up on the surface of the drum so as to reduce the transmission ofheat between the drum and the strip. In order to prevent this, a block of suitable abrasive material R is maintained in contact with the surface of the drum so that the burnt products are continuously scraped off and the contact heat resistance between the drum and the strip maintained at a constant point.

In order to maintain the operation continuously, a duplicate of the support 0 and a duplicate of the winding device I are provided, and as the inner end of the coil is reached, the outer end of the succeeding coil is attached thereto by wellknown means. As the joint between the two coils reaches the winding device I, the two coils are separated by a shearing device, and the end of the second coil is wound on the duplicate winding device. 1

By preference, the maintenance of the exterior surface of the drum at a predetermined temperature at all times is effected by automatic means. Provisions are-made whereby a variation in the surface temperature in the drum, or tendency to variation, causes an automatic adjustment of the heating burner so that the tendency to temperature variation is overcome. In Figs. 3, a and 5 of the drawings,'I have shown a burner control suitable for the purpose. In this particular instance, a hole 10 is bored into the peripheral wall of the drum A in an axial direction. A pyrometer couple ll of well-known form is inserted into this hole and surrounded by suitable insulating material 12. Preferably, the exterior of this hole is at the end of the drum opposite to that into which -the burner structure is inserted. Contact rings l3, l4. separated by suitable insulating material 15, are supported so that they lie in a plane at right angles to the axis of the drum, and the exterior ends of the thermo couple 11, which are indicated at l6, 17 are arranged so as to make sliding contact with these contact rings. These contact rings are connected by

wires

18, 19 to an automatic burner control apparatus 20 of wellknown type, which is diagrammatically shown in Fig. 3. This apparatus so controls the supply of air and gas to the gas burner as to maintain the temperature of the exterior surface of the drum at the required point.

In Fig. 6 of the drawings, I have shown in a somewhat diagrammatic manner, a modified form of the apparatus in which two drums A and A are employed, it being understood that each of these drums has its interior heater. The rollers which hold the strip in contact with the surface of the drums are shown at E and E. It is apparent that the strip first passes around idler E", then around drum A and then around drum A to idler roller FE, and thence to the pinch rolls (not shown). By using such an apparatus, it is evident that the strip will be heated first from one face thereof and then from the opposite face thereof so that after treatment both faces of the strip will have been held in contact with the exterior surface of the hollow cylindrical heating device. Such an arrangement is particularly desirable where the strip is relatively thick, in fact so thick that it is difficult to bring it to a uniform heat by passing heat into the same at one side only.

In the operation of apparatus of this characterthere is considerable variation in the width of the strips being annealed and in order to avoid the necessity of heating a greater area of the drum surface than is actually required, and in order to center the burner nozzle relatively to the strip being annealed, I may employ an adjustable burner mounting such as indicated, for example, in Figs. 7 and 7 In this case, the burner nozzles 21 project at right angles to the wall of the drum and each is adapted to emit a series of narrow flames -in the direction of the drum circumference. The fuel pipe 22, leading to the burner nozzles, is slidably mounted in

supports

23 and 24. An arm 25 is adjustably attached to the burner pipe 22 and held in any required position by set screw 26. Pivoted to arm 25 is a link 27, the out ward end of which engages with a crank arm 28, to which it is adjustably'secured by stud 29 and nut 30.1 Crank arm 28 is mounted on a shaft 31 rotated by any suitable means. Air and

gas supply pipes

32 and 33, respectively, are coupled to the sources of air and

gas supply

34 and 35, respectively, by

flexible pipe connections

36 and 37; respectively. By suitable adjustment of the arm 25 to the effective radius of the crank arm 28, the

burner maybe caused to heat uniformly any particular width of the drum, and the burner can be centered relatively to the strip being annealed. It will be understood that preferably a plurality of radial burner nozzles are all adapted to be adjusted together in a direction lengthwise of the drum. It is apparent, however, that various means can be employed for heating the drum interiorly; for example, an electrical heater could be employed, or one using oil as a fuel.

It will be seen that it is possible by my invention to heat treat coils of large size in a very satisfactory manner. The degree of uniformity to which the strip is heated is much greater than that which can be obtained with the use of previous heat treating apparatus. The cost of the apparatus is relatively small and this is a considerable advantage. If necessary, the apparatus can be surrounded by a suitable envelope into which a suitable gas atmosphere can be introduced for the purpose of preventing or greatly reducing the oxidation of the surface of the metal beingtreated.

By my improvements, it is possible to obtain a very nice control of the crystal diameter of the metal strip, and it is also possible to secure uniform heating of all parts of a coil of strip metal. Furthermore, it is possible by the employment of relatively inexpensive apparatus to obtain uniformheating of all parts of large coils having many convolutions, and this is a result greatly desired by rolling mill operators at the present time.

My new method is not confined to the treat ment of strip metal and can be used for the Lil treatment of wire and other materials.

Various changes can be made in the details of the method and apparatus without departing- -metal will vary with the speed at which the strip travels.

2. A device for heat treating a coil of metal strip comprising means for unwinding and rewinding the strip, a rotatably mounted body, means for directing said strip over and in contact with the surface of said body in its passage to the rewinding means, interior means for heating said body, and means for varying the point of application of heat to said body laterally in respect to the strip.

3. A device for heat treating strip metal comprising means for supporting a coil strip, means for drawing said strip from the coil, a rotatable drum mounted between said first-named means,

surface of said drum, means for heating said drum from the interior thereof, automatic means for controlling the temperature of the drum, and means for varying the point of application of heat thereto.

4. In a device for heat treating strip metal, a hollow body, variable speed means for drawing the strip to be treated over and in contact with the periphery of said hollow body, heating means within said hollow body, automatic means associated with said heating means and with the periphery of said hollow body for maintaining the peripheral portion of said body at a constant temperature, and means for maintaining the surface contact condition between the strip and body against substantial variation.

5. In a device for heat treating strip metal, an interiorly heated body, variable speed means including pinch rolls and an electric driving motor therefor whereby the strip is drawn over said body at any of a number of different speeds, and automatic means for maintaining the temperature of the peripheral portion of said body substantially constant.

6. In a device for heat treating strip metal, an interiorly heated body, variable speed means for drawing the strip to be treated over and in immediate conductive'contact with said body, means for maintaining the surface contact pressure of the strip against the body substantially constant, and automatic means for maintaining the periphery of said body at a sub stantially constant temperature.

'7. In a device for heat treating strip metal, a cylindrical body, means within said body for heating the peripheral portion of the same, means including a variable speed electric motor for drawing a strip over and in contact with the periphery of said body, means for preventing variations of temperature in the peripheral portion of the body, and conditioning means for maintaining a clean surface of contact between the'strip and the body.

8. In a device for heat treating strip metal, an interiorly heated body, variable speed means for drawing the strip to be heated over and in contact with said body, a tension device acting on the strip, means engaging the periphery of said body for maintaining: free of deposits, and means for controlling the temperature of the peripheral portion of said body automatically. A v 9. In a device for heat treating strip metal, a rotatable hollow body, heating means for'said body located within the same, variable speed means including pinch rolls and a driving electric motor therefor whereby the strip to be treated is drawn over and in contact with said body, a tension device for the strip, means engaging the periphery of the body to keep it clear of deposits, and automatic means for maintaining the peripheral portion of said body at a substantially constant temperature.

10. In a device for heat treating strip metal, an interiorly heated rotary body, means for directing a strip in immediate conductive contact with the exterior of said body, pinch rolls for body, variable speed means for drawing the strip to be treated over and in contact with the periphery of said body, and automatic means associated with said burner andhaving an element located at the peripheral portion of said body for maintaining the temperature of the peripheral portion of said body where the same is contacted by said strip substantially constant.

12. In a device for heat treating strip metal, a hollow rotary body, a device located interiorly of said body for heating the peripheral portion of the same, and means for adjusting said device axially of said body to vary the heating efiect upon the peripheral portion of said body.

13. In a device for heat treating strip metal, an interiorly heated body mounted to rotate on its axis, automatic means for controliing the temperature of said body at the periphery thereof so that it remains substantially constant, means for directing the strip into contact with and over the peripheral portion of said body so that the body may rotate as the strip passes over it, and means for drawing the strip over the body at any of a number of different speeds so that the crystal size of the metal will vary as the speed of the strip varies.

l t. In a device for heat treating strip metal, an interiorly heated round body adapted to rotate about its axis, said body having a smooth periphery, means for maintaining the periphery of said body at a substantially constant temperature, means for directing the metal strip into contact with and over said body so that the body will be rotated at substantially the same speed as the strip moves when the strip is drawn over the body, and means for drawing the strip over the body at any of a number of diiferent speeds.

15. In a device for heat treating strip metal, an interiorly heated round body adapted to rotate about its axis, said body having a smooth periphery, means for maintaining the periphery of said body at a substantially constant temperature, means for directing the metal strip into contact with and over said body so that the body will be rotated at substantially the same speed as the strip moves when the strip is drawn over the body, and means for drawing the strip over the body at any of a number of different speeds, said last-named means comprising a variable speed electric motor. I,

16. In a device for heat treating strip metal, an interiorly heated body, variable speed means for drawing the strip to be treated over and in immediate conductive contact with said body, conditioning means for maintaining the exterior surface of said body contracted by said strip free of deposits, and automatic means for maintaining said surface at a substantially constant temperature.

17. In a device for heat treating coiled strip metal, an interiorly heated substantially cylindri-= cal body adapted to rotate about its axis and hav-