US1812320A - Annealing - Google Patents

Description

June 30, 1931. F. G. c'ARRlNG-TON 1,812,320

A ANNEALING Filed Nov. 7, 1928 4 Sheets-Sheet l attenua* June 30, 1931- F. G. CARRINGTON 1,812,320

` ANNEALING Filed Nov. 7., 1928 4 Sheets-Sheet' 2 June 30, 1931. FQG, CARRlNGTQN 1,812,320

ANNEALING Filed Nom*v 7, 1928 4 Sheets-Sheet (5 June 30, 1931.

F. G. cARRlNGToN 1,812,320

ANNEALING Filed Nov. '7, 1928 4 Sheets-Sheet 4 Hai ///// Ziff /5 effects of the annealing temperatures.

Patented June 30, 1931 UNITED STATES. PATENT OFFICE FRANK G. CARRINGTON, OF A NNISTON, ALABAMA, ASSIG-NOR TO FERRIC ENGINEERING COMPANY, OF ANN'ISTON, ALABAMA, A CORPORATION OF DELAWARE ANNEALING Application led November 7, 1928. Serial No. 317,818.

This invention relates to annealing, and more particularly has reference to a process and app-aratus for annealing pipe.

' The annealing of pipe as heretofore prac- 5 ticed hasbeen attended by certain outstanding disadvantages. In the first place it has been directed largely to only the softening of the meta-l by reducing the combined carbon content of the pipe, and has disregarded all othe complete utilization of the heat treatment necessarily comprehends a regulation of the crystal size, internal stresses, oxidized coating, surface decarbonization, and blisters.

Failure to control the above factors has, perhaps, been a necessary consequence of the type of apparatus formerly employed for the annealing of pipe. The ovens used prior to this. time have been of a type that render any close regulation of temperature therein impossible.

' rllhe method of inserting and maintaining the pipe in the ovens has been undesirable in several respects. The process most frequently used is to rollthe pipe through the oven either by means of rollers, cams, or some other similar form of conveyor. This results in the establishment of heat transfen areas at those points Where the pipe contacts with the conveying means. 'A further irregularity in temperature along the pipes length is frequently produced Where the oven is heated from each side, which is the conventional practice.l The course ofthe combustion gases in an oven of this character issuch that the pipe lis heated to a greater extentat the center than at either end. The result of this I irregular heat distribution is that certain points along the pipes length are fixed for the desired temperature, and all other points are subjected to a temperature either below or .in excess of this temperature.

A further disadvantage in the annealing apparatus heretofore'used has been anjnability to lregulate the temperature of the oven along its length. Burners or other heating means are spaced on the sides along the length of the oven, and necessarilyl at so-me distance from the center of the pipe, and the heating effect of these media is usually graduated throughout the oven. In view of the fact that the heating means are spaced some distance'from the center of the oven, there 1s a consequent intermingling of the gas With that from the heating medium adjacent to it. It is, therefore, impossible to accurately con-A trol the temperature along the length of the oven. f

The foregoing relates to any type of pipe, and While my invention is adapted for use With a pipe cast by any of the conventional methods, it is particularly valuable for the treatment of pipes cast by the centrifugal process. lVith pipe that has been centrifugally cast the above disadvantages are accentuated, and in some particulars the prior methods of annealing have been found totally Wanting in the treatment of this kind of pipe.

The product of a centrifugal casting operation has several marked differences from that cast by other processes. The molds ernployed in a centrifugal casting apparatus are usually of metal construction, or sand reinforced by a metal jacket, for it has been found that molds made entirely of sand cannot Withstand the pressures generated in centrifugal casting. The presence of metal gives the mold more pronounced thermal conductivity propcrt-ies, and requires that the mold be artificially cooled. These properties result in a greatertendency. for the casting to be casechilled, and consequently increase the necessity for lan annealing process.

In addition, the centrifugal force generated by a rotary mold makes for a casting of considerably greater density than would be the oase if the casting Were made by a process -other than the centrifugal method. The granular structure of the casting iscloser, which, While resulting in a product of considerably greater strength, introduces into the annealing of the objects factors not ordinarily present.

To overcome the above and other` disadvantages inhering in the prior art is one of the objects of my invention.

Another object is to devise a method of annealing pipe whereby the temperature of the pipe may be closely regulated at any moment 3o ence is made to the accompanying drawings support for pipe;

'in the oven;

while it is in the oven, and the heating along the length off the pipe may be exactly controlled.

A further. object of my invention is to devise a method of annealing pipe whereby the temperature of the interior of the pipe may be accurately controlled.

Yet another object of my invention is to devise an economical and eliicient annealing process for pipe.

A still further object of my invention is to provide an apparatus for annealing pipe in which the temperature at any point within the apparatusmay be closely controlled.

To accomplish the above, and other important objects, as will more fully appear herein, my invention in general comprises a process and apparatus for annealing pipe that are both inexpensive and efficient, in which the temperature to which both the interior and exterior of the pipe are subjected may be closely regulated along its length, and the time during which tle pipe is exposed to a given temperature may be accurately regulated.

In order to insure a complete comprehension ofpmy invention, but wishing it to be distinctly understood that various modifications may be made therein without departing from the true scope of the invention, referin which the same element is referred to by similar numerals:

Figure 1 is a top view of an annealing oven and associated track and power means;

Figure 2 is a side elevation view ofthe device shown in Figure 1;

Figure 3 is a front elevation view of the feeding end of the apparatus;

Figure 4 is asectional view along the line 4-4 of Figure 1, looking in the (direction of the arrows;

Figure 5 isa view along the line 5-5 of Figure 4, looking in the direction of the arrows' Figure 6 is a view along the line 6-6 o'f Figure 4, looking in the direction of the arrows v Figure 7 is a view along the line 7--7 of Figure 6, looking in the direction of the arrows' Figure 8 is a view along the line 8 of Figure 4, looking in the direction of the arrows;

Figure 9 is a detailed View of an opening Figure 10 is a sectional view of a modilied Figure 11 is a view in detail-of a reciprocating plate.

Referring in more particularity to the drawings, -and-especially to Figures 1 and 2, there vis shown an'oven 1, made of lire brick or other refractory material adapted to withstand, :and

conserve, the heat introduced into thein-v terior of the oven. A The walls and general the length .of the oven, and are positionednear the base of the oven as shown more particularly in .Figure 2. By providing these ports at close and regular intervals, it is pos-A sible to control the temperature along the length of the oven by regulating the heating means at each port. If, for instance, it were desired to heat the oven uniformly along its length, a uniform temperature at each of the ports would insure this, for the proximity of the ports prevents any areas of lag between them.

Mounted in each port 2 is a burner 125. Referring more particularly to Figure 6, it will be noted that these burners are similar to the conventional Bunsen burners, comprising a jet 126 which supports, by means of a spider or other suitable means, a casing 127. Adjacent the casing 127, a plate or disc 128 is mounted upon the jet 126, which serves to maintain a strong draft of air through the casing 127, and thus increase the combustion of the gas dispersed from the jet. The jet is fed with the gas by a supply line 129. Each burner is providedwith a regulating means (not shown) whereby the amount of gas supplied each burner may be controlled and consequently the flame issuing therefrom. In operation, a draft of air is set up in the oven, and fresh air entering through the ports 2 is heated by the fla-mes from the burners 125. This air rises. and passes out of the furnace as will be later described.

It is, of course, within the purview of my invention, to substitute other heating means for the burners here shown. For instance, the temperatures may be obtained by supplying the ports with heated air or an inert In Figures 1 and 2 I have shown diagrammatically doors 3 and 4 at the receiving and discharging ends of the oven respectively. These doors are adapted to retain the heat within the oven, and may be of a hinged or roller type, 'operated either mechanically or manually. In the usual operation, the door 3 is normally maintained closed, and is opened only when a pipe is inserted in the oven. The same applies with respect to door 4 when the pipe is discharged from the oven.

Spaced along both sides of the length of the oven are chimneys 5 for the emission of the heated air or gases after they have performed their function, and the heat emerging from these chimneys may be either dispersed into the atmosphere, or recycled and reheated to effect an economy. The exact positions and number of these chimneys are optional, depending upon various factors. They should, however, afford an adequate outlet for the heated air after passing over the pipe, and, if opening. into the atmosphere, should be of such vconstruction as' to produce sufficient draft tothe desired circulation within the oven. If the air is recycled, an appropriate pump or fan is installed in the system to insure the necessary draft, and it may be preferable to provide such mechanical means to force the air into the oven even if the chimneys open into the atmosphere.

As shown in Figures 4 and 6, the oven comprises `side walls 6 and a ceiling 7. The ceiling 7 is provided with a slot 8 centrally positioned and running longitudinally `of the oven. This slot 8 is of a'restricted width, and its function will be describedV hereinafter.

Serving as a support for boththe oven and alsofor a conveying mechanism are a series of buckstays 9 oppositely disposed on each side of the oven along its length. These buckstays comprise pairs of channel-bars, suitably imbedded in thefoundation. These buckstays are particularly desirable 'in vieuT of the fact that the slot 8v runs the entire length of the oven forming in effect overhanging projections on the side walls 6. Spanning each oppositely disposed buckstay 9, and at a suitable distance above the ceiling 7 is channelbar 11, which, of course, is properly secured to the supports 9.

The cross sectional view Aof the oven, set forth in Figure 6, shows the'ports 2 through whichI air is introducedv into the interior of Athe oven. These ports are connected ,to vertical lchannels' 12, which extend to substantially the ceiling'7 As indicated by the dotted lines in Figure 4, the channels 12 are preferably of the same width as the ports 2.

' Opening from each channel 12 into cham-.

ber 13 of the oven are ports 14. These ports, as will be .observed from Figure 6, are spaced at predetermined intervals along the helght of the lchannels 12. The intervals between.

the ports 14arepreferably uniform, so that when all of the ports are open, there will be 'an introduction of heat into the chamber 13 As the air passes through the ports 2, it`

enters the ochannels 12. From the cannel 12 it will passjout through the various ports 14 into the chamberl 18 according to the degree to which the ports 14 are opened.

The amount of gas entering the chamber 13 from any given port 14 may be controlled by means of blocks 15 positioned'in the ports 14, and which are shown in more detail in Figure 8. These blocks 15 are' substantially the height of the ports 14, and, while shown as not being anchored in the ports 14, may, nevertheless, be provided with a pivot about which they may swing. The position of these blocks 15 within the ports 14 may be varied as shown in Figure 8, and, depending upon the position of the blocks, the amount of gas introduced into the chamber 13 may be varied.

Running from the outside of the walls 6 to the channels 12 are openings 16. @ne of these openings is located opposite each of the ports 14. A rod or other suitable implement .suliicient size to totally cover the opening 16,

and is pivoted as at 18 to permit of a ready opening and closing of the'passage. A lip 19 is provided, which lits within a bracket 21 mounted on the side of the wall, which normally maintains the cover in a closed position, completely preventing'a passage of heat through the opening 16.

It will be readily seen that by means of the arrangement .of the ports 14 and the blocks 15, there may be a close regulation of. the heat at any point within the furnace. The proximity of the ports 14, not only to those above and below, but to those on either side, obviates any possibility of lags between different ports. The blocks 15 permit a nicety of control of the heat emitted from any given port.4 While ordinarily it is desirable that a uniform temperature exist along the ventire length of the pipe, under certain circumstances it may be desirable to Vary the heat along the length of the pipe, for instance the bell of the pipe, by reason of its greater thickness, may require a more intense heat treatment than is necessary for the barrel.

-This can be readily taken' care of by opening sitions of the blocks 15 will depend upon operating conditions, and can be readily ad;

justed accordingly.

Immediately adjacent the ceiling 7 and in above stated, the number and positions of the A chimneys 5 are optional, depending uponvarious conditions, and consequently the same considerations apply to the channels 24.

The channels 22, 23 and 24 conduct the heated air from the chamber 13 to the chimneys 5, from which latterthe air is either dispersed into the. atmosphere or recycled. By providing a channel 22 directly above each row of ports 14 the air from any given row of ports 14 rises within the chamber 13 and passes out of the oven through that chamber 22 which is above the inlet ports. This arrangement prevents any extended overlapping and intermingling of air from the different ports, and permits a close control -of the temperature within any given area.

Referring particularly to Figures 2 and 6,

the operation of the oven is readily discernible. For purposes ofeconomy it is usually desirable to heat the pipe as rapidly as possible to the maximum temperature and then control the cooling. 'The rapid heating saves time, which is essential in this operation, when the number-,of pipes to be treated is considered. Consequently, the burners 125 in those inlet ports 2 at the entrance end of the oven will be regulated to produce the greatest heat, and the iames of the burners in the other ports will be regulated according to the exigencies of operation. There will, therefore, be a close control of the temperature along the entire length of the oven. v

The next consideration then is a control of the air that entersthe chamber 13 from the ports 14. The arrangement shown in Figure 6 provides adequate means for this regulation. If it is desired to heat the pipe at the same rate along its length, the blocks 15 will be adjusted in the ports 14 substantially uniformly, making proper allowance, however, for the tendency of the heated air to rise to the 'top of the chamber 12,1ather than pass uniformly through the various ports 14. This regulation of the blocks 15 is effected by inserting a rod through the openings 16 and moving the blocks to their proper positions.

The gas discharged from any row of ports 14 is confined to that area of the oven, for

in the absence of unexpected drafts within the oveny it rises and passes out of the oven throughthe' channel 22 above the ports.

As above stated, the slot 8 in the ceiling of the oven is .of a restricted size, and very little of the hot gas escapes therethrough. As has also been heretofore described, the doors 3 and 4 are closed except for a moment when a pipe is insertedfor withdrawn from the oven. As indicated inlFigure 6, it will be noted that these doors are of a relatively small size, sucient, however, for the free passage of pipe therethrough, a large portion of the chamber 13 being closed by an end wall 2,6.

The pipe is passed through the oven and the various zones of temperature therein established by the heating means as above y described. The conveying mechanism for the pipe comprises a collar 27 of heat resistant metal, and is of slightly larger diameter than the barrel of the pipe. This collar may be readily slipped over the s igot ,end' of the pipe and passed along the gages the bell.

The pipe may therefore 4be suspended by its bell during its passage throughv the oven. f

arrel until it eny tire length of the pipe. Furthermore, this area is on the bell, which portion of the pipe is best able to withstand such'a condition. The increased thickness of the bell is suiiicient to insure .requisite strength, even in the presence of inadequate annealing. As above stated, the prior processes have set up heat conduction areas along the barrel of the pipe, which are detrimental, and are avoided herein.

As shown in Figures 4 and 6, the 'collar 27 is provided'with studs 28 oppositely disposed on its outer circumference. A 'stirrup 29, made of a heat resistant metal and having hooks 31 adapted' to engage the studs 28, supports the collar 27 and the pipe 32 contained therein. Thestirrup 29 is engaged by a hook 33 which extends upwardly through the slot 8 and is supported in a carriage designated generally 34. As above stated, the slot 8 is relatively narrow and of a size suiiicient only to receive the hook 33, with an allowance for sli ht displacement of the hook. y

-Vhen casting plain-end' pipe, a modified form of support such as shown in Figure 10 may be used. A straight shaft 131 is substituted for the hooky 33, which extends provided with suitable means (not shown)` for fixing them with respect to the shaft.

Spokes 135 and 136 extend from the hubs 134.

and support the converging walls 137.

As above stated, the prior annealing proc' esses have been undesirable in thatthepipe has been supported by-the barrel. This oontact on the exterior of the barrel sets up heat los transfer areas which render the casting inferior. The modified form of support shown in Figure 10, suspends the pipe with its eX- terior free from any contact whatsoever. The points of engagement between the support and the p-ipe are very limited and occur only at the ends of the interior of the pipe. By providing spokes 135 and 136, rather than solid plates, a free circulation of air through the pipe is permitted. Itis, of course, obvious that the modified form of support may be used with bell and spigot pipe as Well as with plain-end pipe.

Referring particularly to Figure 7, the carriage 34 is of cast iron or other suitable material and comprises a frame member 35 having a comparatively low front and a high rear, the purposes of which will be later discussed. Secured in the frame 35 is a pair of stationary axles .-36 on which are rotatably mounted grooved rollers 37 adapted to fit and roll upon a track made up of a pair of spaced tubes 38.

The frame 35 is provided with acircular recess 39 intermediate the two axles 36. A bearing 41 fits Within the recess, and is provided With a ball race adapted to receive a set of brass or nickel steel ball bearings 42. Another bearing 43, likewise provided With a ball race to correspond to the one in bearing 41, is also fitted Within the recess 39.

Securely fitting over the bearing-43, and adapted to rotate in' the recess 39, is a socket 44. The socket 44 and bearings 41 and 43 are preferably composed of machined steel.

' The body of the socket 44 is recessed as at 45 to receive a machined steel ball nut 46 on the end of the hook 33. The ball nut 46 and the recess 45 form a ball and socket joint for the hook 33. The frame 35, bearings 41 and 43 and the socket 44 are cut away in order to form a frusto-conical opening through Which the hook 33 extends. This permits of a limited movement of the hook 33 with respect to the carriage occasioned by jarring or swinging of the pipe.

The socket 44 is secured in its seat by means of a top plate 47 which has aA downwardly projecting annular flange 48 fitting Within a flange 49 on the socket 44. This prevents any displacement of the socket 44 and insures a tight -seating of the socket within the recess 39. The top plate 47 is secured to the body portion 35 by means of bolts 51 or other suitable fastening means.

As above stated, the front portion of the carriage 34 is lower than the rear, and the top plate 47 extends Ifor a certain distance to the rear of the front on aninclined plane as at 53, and thence on a plane parallel to the horizontal plane of the carriage to the elevated rear end of the carriage as at 54. It willhe observed that the top of the portion 54 is flush with the top of the rear end of the carriage. The back of the carriage near the-` the rotation of the socket 44, particularly when the hook 33 isvsupporting a pipe, Will effect rotation of the pipe.

As has been heretofore pointed out, the heat is introduced into the chamber 13 from the opposite side walls, and this provision for rotating the pipe during its passage through the oven insures that the pipe is subjected to a uniform heat treatment circumferentially. In Figure 5 the sockets 44 are shown provided With five fingers 57, which means that the pipe is rotated by fifths. The number of fingers may be varied, of course, although I have found that five is the preferable number.

lVhile I have shown a highly satisfactory form of carriage, it is, of course, obvious that other means for supporting the pipe While traversing the oven may be employed.

Bent around the axles of each carriage are rods or bands 58. These rods or bands depend from the axles and support a plate 59 composed of fire clay or other suitable refractory material. Hooks 61 are embedded in the block 59 and are appropriately linked to the rods 58. An aperture 62 is pro-vided in the block 59 through which extends the hook 33, or shaft 131. This aperture is of restricted size and permits only limited movement of the hook 33 With respect to the plate 59.

As is shown in Figure 6, the plate 59 is supported a short distance above the top of the ceiling 7, and is for the purpose of diverting any hot gas that might pass from the furnace through slot 8. As has been stated,

very little heat from the chamber 13 escapes through the slot 8, but the plate 59 protects the carriage 34 and associated mechanism from what heat does pass through the slot 8.

The tube rails 38 are supported by standards 63, and are secured to these standards by Welding, brazing or other appropriate fastening means. The standards 63 are provided With fianges 64 in which pockets 65 are formed for the reception of the rails. These standards are secured to the cross-bars 11 by means of bolts 66, although it is, of course, to be understood that rivets or other equivalent fastening means'may be employed.

A pair of spaced bearings 67 is provided on I-beamreciprocates, as `will be hereinafter pointed out. The flanges 69 on the .rollers 68 serve as guides for the I-beam and confine any movement of the I-beam to a reciprocation or longitudinal movement. f As shown more particularly in vFigure 7, s aced at intervals along the I-beam 71 are bracketsj 2 which are secured thereto by bolts,

rivets, brazing, welding or otherl appro riate securing means. One end of the brac et 72 is enlarged as at 73, providing a socket for a pivot pin 7 4. The pivot pin 74 passes through the end of an arm and permits an oscillation of the arm 75 about the pin 74 as a pivot. i As shown in Figure 7, the arm 75 is adapted to lit into the socket 56 on each carria e.

l movement of the I-beam to the right, as shown in Figure 7, therefore pushes the carriage 34 in the same direction. When the I-beam 71 is moved to the left,'the -arm 75 slides along the top of the succeeding4 carriage 34 and fits into its socket 56. Th1s carriage then may be moved to the position occupied by the immediately preceding car# riage. It will, therefore be seen that reciprocationof the I-beam 7l results in a passage ofthe carriages from left to right the length of the oven. When no carriages 34 are in the oven, the arm 75 swings vertically from :the bracket 72, .but the rst carriage to enter the oven readily raises the arm 75 in position for operation. The top plate 47 of the carriage 34 is inclined as at 53 in order to permit a proper engagement of the arm 75 in the socket 56 of the receding carriage. n Reciprocation of the I-geam 71 is effected by the mechanism shown in Figures 1 and 2. This comprises a rod 76 pivoted to a bracket 77 mounted on the I-beam 71. The o posite end of the shaft 76 is pivoted to a Eracket 78 integral with or secured to an eccentric strap 79. The vstrap 79 fits upon an eccentric 81 which is mounted upon a shaft 82. The shaft 82 is supported in standards 83 mounted upon a suitable base 84. l Rotation of the shaft 82 therefore imparts a reciprocatory motion to the I-beam. The base 84 must be of such a height' as to place the eccentricl in an operative position for the I-beam 71. A gear 85 is keyed on the shaft 82, and meshes with a gear 86 on a motor 8,7 or other suitable driving means.

The `I-beam 71 is -therefore recip'rocated when the motor 87 is running. This reciprocation of the I-beam causes the arm 75 to engage one of the carriages 34 and move it the' length of the stroke of the I-beam 71. On the return stroke the arm 75 passes over the succeeding carriage and engages `its socket. The succeeding carriage is then moved to the position formerly occupied by the preceding carriage, which in turn has been moved one stroke further on.

Referring again to Figure 6, there is shown a pipe 88, which passes through the side wall 6 of the oven. rlhis pipe is providedV spigot end'of the pipe and the top of the section 90, although provision should be made for any possible irregularity in the position of the pipe.

rlhe pipe 88 Ais joined to a feeder 91, which runs the length of the oven and conveys a heated air or gas to the various pipes 88 positioned along the oven. The particular pipe 88 shown in Figure 6 is enthreaded in a fourway joint 92. A section 92 is threaded in the oint 92 opposite the pipe 88, and its other end ,connects with a valve 93 for regulating the admission of the heating mediumfinto the feeder. 91. Tapped into the-joint, and perpendicular to the pipes 88 and 92 is the feeder 91. The valve 93 receives the heating medium from a pipe 94, which is connected to a suitable source of hot gas or air. This may lbe an independentsupply, or may be drawn off from the chimneys 5 and reheated.

The yvalve 93 is provided with a control stem 93 which, wh-en'rotated in one direction, opens the valve and when rotated -to a position in the opposite direction, closes the valve. Connected to the stem 93 by a'suitable cou- .pling 95 is a shaft 96 journaled in bearings 97, which are mounted upon a buckstay 9. Thrust bearings 98 are also provided -inaddition to the bearings 97 in orderto prevent any axial movement of the shaft 96. This shaft'may be bent as shown in Figure 6 to form a lever 99, or an independent lever 99 may be provided and suitably secured to the shaft 96.

Mounted on the free end of the lever 99 is a sleeve 101, which telescopes over a rod 102. The rod 102 is bent as at 103, andthe bent portion fits within a slot in a plate 104,

mounted on the I-beam 71.

Referring to Figure 11, the slot 105 in the plate 104 is of a length to permit reciproca- 'tion of the plate for substantially the length lis then either opened or closed. The sleeve 101 permits the rod 102 to telescope within it, and thus compensates for the change in length completion of the return stroke to the left,L

forthe slot 105 and the plate 104 provide a means for free movement of the I-beam 71 during the major part of itsstroke, without a corresponding movement of the rod 102. Just prior to the completion of the stroke to the left the plate 104 contacts with the rod.

' 102 and forces the rod along with it. This in turn closes the valve, and the valve remains closed during substantially all that time. when the carriages 34 are in motion.

It will, therefore, be seen that this arrangement provides for an emission of the hot gas or air from the section 90 during that period when a pipe 32 is above it. The section 90 disperses the gas inside of the pipe (there being little oportunity for an escape lof the gas around the outside) and provides j gas is directed upon lthe a' means of vclosely regulating the heat condition of the interior of the pipe as well as the exterior.- Of course, without this arrangement the interior would be subjected t0 the more or less same degree of heat treatment as the exterior, but various factors enter4 which -frequently result in a different treatment inisde of the pipe from that obtained on the outside. This, of course, is particularly true in the case of an annealing process similar to my invention, forI the hot ipe from either side, and consequently the inside of the pipe gets only an incidental heat treatment. The provision which I have made enables an operator to regulate the interior temperature of the pipe to conform exactly to that on the outside, or at any desired ratio.

lIt is, of course, to be'noted that other means may be employed to synchronize the discharge of the gas from'pipe 90 with the positioning of the pipe 32. This might comprise a chain of gears connected with the eccentric 81, or other appropriate mea-ns.

Referring particularly to Figures 1 and 2, it will be observed that the track 38 is continuous. After it passes the discharge end ofthe oven it curves as at 106 and then proceeds in a straight direction as at 107vfor a short distance. From approximately the discharge end of the oven the track slopes downwardly andthe carriages by gravity proceed of their own accord. This grade continues around another curve 108 and thence down the straightaway 109. Appropriate standards 111 from which depend brackets 112 similar to brackets 63 are provided to support the track.

At some place along this track provision may be made for removing the pipe from the carriage, preferably by disengaging the stirrup 29 from the hook 33. This may be done manually or by mechanical means. At the end of the straightaway 109 the track curves as at 113 and thence proceeds in a'horizontal plane for a short distance as at 114.

An upwardly inclined section' 115 serves to raise the carriages 34 to slightly above the level of the track 38. A more or less graduated downward slope 116 provides a meansv The carriages 34 are forced up lthe incline 115 by means of a belt 117. This belt is frictionally mounted upon rotatable members 118, 119 and 120, one at leastl of which is actuated by appropriate means not shown. A supporting bracket 121, held b means vof standards 122 serves to rotatab y support the members 118, '119 and 120. The belt 117 is provided with blocks 123 which engage the rear ends lof the carriages 34 and push them up the incline 115.

It will therefore be seen that this annealing process is a continuous operation, and, as far as the passage of the pipe through the oven is concerned, requires supervision only to the extent of loading the pipe,upon the carriages 34 and removing them therefrom. These two operations might well be carried on at approximately the same location, preferably along the stretch of track 114.

Referring to Figure 4 in particular, it will be observed that a series of fingers 124 are spaced along the I-beam 71, preferably adj acent the several lates 72, and extending downwardly a su cient distance to engage the rotatable fingers 57 of the socket 44. On each return stroke the arm 124 engages a finger on the succeeding carriage, which results in a partial rotation of the pipe prior to each step throughvthe oven. This insures a uniform circumferential,y heat treatment of the pipe.

From the foregoing, the operation of my invention is apparent. At the beginning of the annealing process the motor 87 and the driving means for the belt 1174 are started. Collars 27 are slipped over pipes until they engage the bells thereof, and the stirrups 29 are fastened around the studs 28. The pipe above stated, this operation is preferably carried out along that section of the track 114. As the carriages are loaded they may be I moved until they are engaged by one of the blocks 123. and hoisted to the track 116.

maybe regulated quite independently of those in the other ports 2, and thus effect thel gradient in temperature along the length of the oven. As the first carriage 34 is ready for the oven the door 3 is opened only long enough to permit its entrance, and immediately closed until the following carriage is ready for entrance. As soon as the carriage enters the oven, it is picked up by the leftmost arm and carried along with the forward stroke of the I-beam 71. On the return stroke the next arm 7 5 picks it up and moves it one stroke further, and so it progresses through the oven.

When the rst carriage enters the oven, the heating medium is introduced into the pipe 94, and as each pipe is standing still and waiting for the next arm 75 to engage it, its interior is subjected to a heat treatment by thel gases emitted from the section of pipe 90. Also, at the time that the ipe 32 is stationary, on the return stroke o the I-beam 71, it is subjected to the full force of the heat emerging from the ports 14, for it is then directly opposite the row of ports.

As has been heretofore pointed out, the design of my invention is such that the temperature within a given zone of the chamber 13 may be very closely regulated. The `provisions made for regulating the tem erature of the incoming gas, and the furt er provision for the control of that gas when it has once been introduoedinto the chamber 13, and until its passage therefrom through the channel 22, make this close regulation possible,

By 'reason of the nicety of control o f the heat within the chamber 13 it is possible to control the various properties of the casting which are affected by heat treatment. There is also the time factor in any annealing yprocess, and this, of course, can be suitably regulated by controlling the speed of the motor 85.

While the pipe is traveling through the oven, it is rotated about its longitudinal axis, and consequently each portion of its vcircumference is subjected to the same heat treatment. There are no areas of conduction along the length of the pipe, except that portion ,of the bell contacting with the collar 27.

The pipe is, therefore, subjected to a unirsiaeae form temperature both along substantially its entire length, and alsoabout its circumference. This obviates any flaws in the pipe resulting from a non-uniform heat treatment. y

When a pipe is about to emerge from the oven the door 4 is opened and immediately reclosed after the exit, thus lretaining the heat within the chamber 13 and also preventing drafts within the chamber. The carriage then ro-lls down the inclined track and the pipe is removed.

The advantages of my invention are apparent. rIhe economical and eliicient apparatus and process, as herein set forth, requires a minimum of labor for the operation thereof. It is to be noted that I have provided an apparatus in which there is a minimum of wear and need for replacement, as well as being economical in initial construction. The arrangement herein insures in the first place,

al uniform heat treatment of the barrel of they conception of my invention is not confined to the details hereinbefore described, and that various modifications may be made therein without departing from the true scope and spirit of the invention.

I claim: v j

1. An annealing apparatus comprising a tunnel-like chamber, means for moving articles to be annealed lthrough said chamber, a plurality of vertical flues positioned in the .walls of said chamber, a plurality of vertically spaced vducts placing each of said flues in communication with said chamber at a plurality of points, a source of heat for each of said lues and means for selectively regulating the amount of heat passing from each of said flues through the several ducts.

2. In an annealing process for bell-ended' pipe comprising passlng a pipe in a horizontal path while vertically suspended from its bell end with its bore open at both ends and progressively subjecting the pipe to zones of different temperatures.

3.' In an annealing process for bell-ended pipe comprising passing the pipe while suended vertically from its bell end with its here open at both ends through successive zones of diiferent temperatures, and rotating the pipe about its axis while passing through the zones. f

4. In lan annealing process for pipe com-l iso a horizontal ath, progressively subjecting the exterior o the pipe to zones of different rtemperatures and progressively subjecting the interior of the pipe to other zones of different temperatures.

5. An annealing apparatus for pipe comprising an oven, heating means spaced longitudinally of the oven for providing zones ofl dilerent temperature within the oven, means f associated with the heating means for controlling the temperature vertically 'of the oven, a support tor suspending a pipe vertically within the oven, and means for progressively moving the support through the` oven to expose the pipe to the different temperature zones.

7 An annealing apparatus for pipe comprising an oven, heating means spaced longitudinally of the oven for providing zones of diiierent temperature within 'the oven, means associated with the heating means for controlling the temperature vertically of the oven, a support for suspending a pipe vertically within the oven, means for progressively moving the support through the oven to expose the pipe to different temperature zones, and means for rotating the support.-

8. An annealing apparatusv for pipe com# prising anl elongated oven, means for heating the oven, means for passing a vertically suspended pipe through the oven, and means located below the path of travel of the pipe for vheating the interior of the pipe.

' 9. An annealin apparatus for pipe coml prising an oven, eating means spaced longitudinally of the oven, a vertical support within-the oven so constructed and arranged to engage an'enlargement upon the circumference of the pipe without materially obstructing the bore of the pipe, and means for movin the support through the oven.

10. n annealing apparatiis for bell-ended pipe comprising an oven, heatingA means spaced lon -tudinally of the oven,'a carriage mounted a ove the oven, means carried by the carriage and extending into thev oven and engaging the bell end only of the pipe without materially obstructing the bore oftheI pipe, and means for moving the carriage.

11. An annealing apparatus for pipe comprising an elongated oven, a series of vertical 12. An annealing apparatus for pi comrising an oven, a support within t e oven or sustaining a pipe in a vertical position but a'ording a continuous passa e for heated gas throughout the interior o the pipe, and means for moving the support through the oven. I

13. An annealing apparatus for pipe comprising an oven, a support within thetoven for sustaining a pipe in a vertical position but affording a continuous passage for heated as throughout the interior of the pipe, means or moving the support through the oven, and heating means within the oven located belo the lower end of the pipe.

In testimony whereofv I aix my signature.

FRANK G. CARRINGTON.

burners mounted within and spaced adjacent the bottom of said oven, asupport for suspending a pipe vertically within the oven, and means for imparting a step-bystep movement to said support to sequentially dispose the pipe over successive burners.

iso

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