US3708354A

US3708354A - Method and apparatus for measuring and controlling the continuous annealing of a long length of metal tubing

Info

Publication number: US3708354A
Application number: US00151257A
Authority: US
Inventors: D Rowell
Original assignee: Anaconda American Brass Co
Current assignee: American Brass Co
Priority date: 1971-06-09
Filing date: 1971-06-09
Publication date: 1973-01-02
Anticipated expiration: 1990-01-02

Abstract

METHOD AND APPARATUS FOR MEASURING AND CONTOLLING THE CONTINUOUS ANNEALING OF A LONG LENGTH OF METAL TUBING BY PASSING THE ANNEALED TUBING BETWEEN SENSING ROLLS TO APPLY PREDETERMINED FORCE URGING THE ROLLS TOWARD EACH OTHER TO CHANGE THE WALL SHAPE AS A WHOLE AS DISTINGUISHED FROM A LOCALIZED INDENTATION OR DEFORMATION. THE EXTENT OF NON-LOCALIZED CHANGE IN SHAPE OF THE TUBING WALL INCREASES WITH THE DEGREE OF ANNEAL, THEREBY PROVIDING A MEASUREMENT OF THE ANNEAL AND PRODUCING AN INDICATION FOR USE IN CONTROLLING THE ANNEALER HEAT. THE CHANGE OF THE TUBING SHAPE FROM GENERALLY CIRCYLAR TO OVAL IS MADE SUBSTANTIALLY PROPORTIONAL TO THE DEGREE OF ANNEAL THROUGHOUT THE RANGE OF OPERATION BY PROVIDING MEASURING ROLLS INCLUDING SECONDARY SUPPORT FOR THE TUBING BY PARTIALLY EMBRACING OPPOSITE SIDES OF THE TUBING WITH SHOULDERS SLOPING TANGENTIALLY AWAY FROM CONTACT. IN THE PREFERRED
ARRANGEMENT FOR PROVIDING UNIFORM ANNEAL ALONG A LENGTH OF COPPER TUBING, A LAVER SYSTEM TUBING, A LEVER SYSTEM WHICH APL ALSO SERVES TO MULTIPLY THE ROLL AXIS DISPLACEMENT AS INDICATED BY THE MULTIPLED MOVEMENT OCCURING AT THE OUTER END OF THE LEVER, AND THE HEAT ENERGY IS FED AT A HIGH RATE SUCH THAT THE DWELL TIME OF EACH INCREMENT OF TUBING IN THE ANNEALER IS A BRIEF PERIOD, THE HOT TUBE IS QUICKLY COOLED, THE SENSING OF THE ANNEAL OCCURS SOON AFTER COMPLETION OF ANNEAL FOR PROVIDING ACCURATE CONTOL OF THE ANNEALING AT A FAST PRODUCTION RATE, AND THE MAXIMUM CHANGE IS TUBING DIAMETER AT THE SENSING ROLL FACES IN THE DIRECTION OF THE APPLIED FORCE IS LESS THAN 25% FOR COPPER TUBING IN WHICH THE WALL THICKNESS IS LESS THAN ONE TENTH OF THE O.D.

Description

0 1973 o. w. ROWELL METHOD AND APPARATUS FOR MEASURING AND CONTROLLING THE CONTINUOUS ANNEALING OF A LONG LENGTH OF IETAL TUBING Filed June 9, 1971 INVENTOR. floag las W/zdmarz Howell United States Patent 01 Rice 3,708,354 Patented Jan. 2, 1973 US. Cl. 148-128 19 Claims ABSTRACT OF THE DISCLOSURE Method and apparatus for measuring and controlling the continuous annealing of a long length of metal tubing by passing the annealed tubing between sensing rolls to apply predetermined force urging the rolls toward each other to change the wall shape as a whole as distinguished from a localized indentation or deformation. The extent of non-localized change in shape of the tubing wall increases With the degree of anneal, thereby providing a measurement of the anneal and producing an indication for use in controlling the annealer heat. The change of the tubing shape from generally circular to oval is made substantially proportional to the degree of anneal throughout the range of operation by providing measuring rolls including secondary support for the tubing by partially embracing opposite sides of the tubing with shoulders sloping tangentially away from contact. In the preferred arrangement for providing uniform anneal along a length of copper tubing, a lever system which applies the force also serves to multiply the roll axis displacement as indicated by the multipled movement occurring at the outer end of the lever, and the heat energy is fed at a high rate such that the dwell time of each increment of tubing in the annealer is a brief period, the hot tube is quickly cooled, the sensing of the anneal occurs soon after completion of anneal for providing accurate control of the annealing at a fast production rate, and the maximum change in tubing diameter at the sensing roll faces in the direction of the applied force is less than 25% for copper tubing in which the wall thickness is less than onetenth of the OD.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a method and apparatus for measuring and controlling the continuous annealing of a long length of metal tubing, the illustrative embodiment of the invention being described in connection with the production of copper tubing. Sensing of the degree of anneal in the tubing is accomplished by passing the tubing between opposed sensing rolls to which a predetermined force is applied urging the rolls toward each other while also partially confining and supporting the tubing wall so as to produce non-localized change in shape of the tubing wall as a whole as it passes between the rolls. The relative movement of the roll axes toward each other is sensed to produce an indication for use in control of the heating action of the annealer.

The invention in its preferred form relates to a method enabling annealed welded copper tubing to be produced in long lengths with a substantially uniform degree of anneal along the length. Highly intensive heating action is applied in the annealer to quickly bring the tubing up to annealing temperature. The tubing is cooled in a liquid bath while avoiding liquid contact with the Welded seam, and almost immediately the degree of anneal is measured by partially confining sensing rolls actuated by a lever system. Thus, a fast acting and accurate control action is obtained which is easy to adjust and maintain and which quickly reaches equilibrium upon start up or in response to changes in the control signal.

DESCRIPTION OF THE PRIOR ART In the prior art there are complex systems disclosed for controlling the annealing of strip material. These involve complicated arrangements for determination of the annealed condition of the strip material and require complicated control systems for the intended control. These prior art systems impose localized indentation on the product and are expensive and difiicult to maintain.

In addition, the prior art often utilizes annealing ovens that are large and bulky such that their temperatures can be changed only over relatively long time cycles due to thermal lag. If the sensing systems in the prior art show that the condition of the annealed strip has departed from that specified, the inherent thermal lag causes a long delay before the oven can be brought to the corrective equilibrium temperature. The large thermal lag in the oven also requires a long period of warm up to reach equilibrium following shut down of the production line for any reason.

SUMMARY OF THE INVENTION The present invention relates to a method and apparatus for measuring and controlling the continuous annealing of a long length of metal tubing by passing the annealed tubing between sensing rolls while also partially confining it to change the tubing Wall shape as a Whole as distinguished from a localized indentation or deformation and using the relative displacement of the roll axes toward each other as an indication to be used to control the annealer station. The illustrative embodiment of the invention, as described, is being practised for annealing tubing containing copper or copper-based alloy, such tubing being generally referred to herein as copper tubing.

In accordance with the invention, the long length of annealed tubing soon after it has been annealed is passed between a pair of opposed sensing rolls. A predetermined force is applied urging the sensing rolls relatively toward each other while partially supporting the tubing wall to change the generally circular tubing shape into an oval configuration. The extent of change of the tubing shape as a whole between the sensing rolls increases with an increased degree of anneal in the tubing. A force multiplying lever provides a multiplication of the applied weight and also provides a multiplication of the extent of roll axis displacement as sensed, with the multiplied displacement being indicated at the outer end of the lever. The position of the lever is also used to provide a control signal for controlling the annealer heating action.

In the illustrative embodiment of the invention, the change of the tubing shape is caused to become substantially proportional to the degree of anneal throughout the range of operation by providing secondary supporting means for partially embracing the tubing wall so as to cause non-localized change in shape. This secondary supporting means in the illustrative example comprises sloping shoulders on the sensing rolls associated with a groove in the rolling surface of each of the opposed sensing rolls which partially embrace opposite sides of the tubing so as to partially support the tubing wall to produce distributed stress in the tubing as seen in cross section, as distinguished from a localized indentation stress. The rolling surfaces of the sensing rolls have such supporting shoulders sloping tangentially away from contact with the tubing surface to confine and guide the tubing during the change in shape. As used herein, the phrase generally circular shape, as applied to tubing, is intended to include tubing having regular polyhedral shape, as seen in cross section, and the phrase ovalled configuration is intended to include regular polyhedral shaped tubing after it has been changed in shape as a whole.

Among the many advantages flowing from the invention are those resulting from the fact that it enables a long length of metal tubing to be produced having a substantially uniform degree of anneal along its length. Moreover, sensing, measuring and controlling the degree of anneal along the tubing are accomplished in an effective method which is accurate in response and provides for ease of adjustment and maintenance.

Another advantage provided by the illustrative embodiment of the invention is that coupled with the fast and accurate sensing, there is an annealer which provides fast response with respect to changing the temperature of the tubing being annealed, and the overall control system is quick to reach equilibrium following start up. Moreover, when an adjustment is made during production, the new equilibrium temperature is quickly reached. Thus, advantageously the degree of anneal produced along a long length of tubing is substantially uniform, because any changes called for by the sensing and control apparatus are quickly brought into equilibrium.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The various objects, aspects and advantages of this invention will become more fully understood from the following detailed description of a preferred mode of putting the invention into practice when considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevation of apparatus for measuring and controlling the continuous annealing of a long length of copper tubing;

FIG. 2 is an enlarged cross-sectional view, taken along line 2-2 of FIG. 1, showing the tubing stabilizing rolls;

FIG. 3 is an enlarged cross-sectional view, taken along line 3-3 of FIG. 1, showing the configuration of the pposed sensing rolls; and

FIG. 4 is a cross-sectional view, taken along line 44 of FIG. 1, through the cooler showing the liquid cooling bath and associated equipment.

The embodiment of the invention which is presently preferred by the inventor is described, but it is to be understood that the scope of the invention as claimed is broader in certain of its aspects than this particular embodiment.

A long length of copper tubing llll which has been formed by longitudinal welding is fed through an annealer station 12, which will be described in detail further below. In the annealer an intensive heating action is applied to the tubing to heat it up to the desired annealing temperature, the heating action being accomplished within a relatively few seconds. The tubing generall regularly polyhedral shaped, most preferably being circular, and hereafter for convenience it is referred to as circular.

From the annealer station 12, the heated tubing passes into a cooler station 14 containing a liquid bath, as will be described later, which quickly cools the annealed tubing down to suitable handling temperature. lust beyond the exit from the cooler, the tubing is passed between a pair of circularizing

calibrating rolls

16 and 18, which assure that the annealed tubing is calibrated to the desired generally circular configuration and it is then passed between the

sensing rolls

20 and 22.

The sensing rolls are relatively movable toward and away from each other, and a predetermined force is applied urging them against opposite sides of the tubing Elli, as shown on enlarged scale in FIG. 3. The lower sensing roll 22 has its axis fixed in position by stationary bearings 24, while the axis of the upper sensing roll '20 is mounted for movement by journaling its axle in bearings 26 carried by a lever system 30.

In this lever system 30, the lever member 32 is a lever of the second class having its fulcrum provided by a fixed pivot 34. The efiort of the lever system is applied by selected weights 36 removabiy placed upon a supporting l scale-type pan 33 held by a wire cable 40. At its upper end, the cable is attached to a clamp 42 which can be adjusted in position along the outer end 44 of the lever 32, so as to be clamped at the desired adjusted position.

It is to be noted that the effort arm of lever system 30 is the longer distance from the fulcrum 3 3 to the point at which the wire cable 40 is attached to the outer lever end 4-4; whereas the load arm is the shorter distance from the fulcrum to the axis of the bearings 26. Thus, the etfort being exerted by the weights 36 is advantageously multiplied several times in applying predetermined force F to the axis of the upper sensing roll 22, so as to urge the rolls 2?. and 2t) relatively toward each other, as indicated by the force arrows F (FIG. 3).

By changing the number and size of the weights 36 and also by adjusting the position of the clamp 42, so as to lengthen or shorten the effective length of the effort arm of the lever system 39, the operator can conveniently and precisely obtain the desired predetermined force F to be exerted upon the sensing roll 20 for the particular wall thickness and diameter of the tubing 10 being annealed. By virtue of the fact that the applied force F is generated by using gravitation acting through the lever system, the applied force remains precisely constant in spite of any other variables.

The lower roll 22 is in opposed relationship to the upper roll 20 and by its reaction to the applied force, the lower roll exerts an equal and opposite force F. As a result of the opposed forces F exerted against its opposite sides, the generally regular polyhedral shape 4-6 of the tubing 10, which is most preferably circular, is changed as a whole into an ovalled crosssectional configuration, as indicated by the dotted lines at 46' in FIG. 3. The maximum change in the initial outside diameter of the tubing in the direction of the applied forces F is less than 25% for copper tubing in which the wall thickness is less than one-tenth of the outside diameter of the tubing.

This ovalled change in the circular shape of the tubing permits a slight downward displacement or travel of the upper sensing roll 20, together with its axis. Moreover, the greater the degree of anneal of the tubing wall 46, the greater the extent of ovalling in the shape. This is an overall change in shape of the tubing wall as a. Whole, as distinguished from a localized indentation or deformation.

The inventor has discovered that the extent of displacement of the axis of the sensing roll 20 can be made substantially proportional to the degree of anneal of the tubing 10 over the full operating range by providing partial confinement and secondary support for the tubing wall 46 as it is being changed in shape. For accomplishing this, the rolling surfaces of the

sensing rolls

20 and 22 are each provided with grooves having curved concave tube-engaging portions 52 which partially embrace the perimeter of the tubing. In addition, secondary support means 54 are provided for supporting the tubing wall to cause it to be bent into an ovalled configuration by non-localized change in shape. This secondary support means 54 comprises sloping shoulders on the concave rolling surfaces. These sloping shoulders extend tangentially from the concave portions 52 shoulders 54 and converge toward the corresponding shoulders on the other sensing roller, as seen in FIG. 3. By this partial confinement provided by the saddle shaped rolling surfaces 52, and the secondary support 54, and by application of the predetermined force F, the shape of the tubing wall 46 is effectively changed by a generalized, i.e. non-localized bending by the applied stress which is distributed to produce a smoothly curved oval deflection without fiat spots.

The inventor has discovered that an attempt to use flat surface" sensing rolls (that is, ones having ungrooved cylindrical surfaces) without secondary support areas is not practical for application to production work. Flat sensing rolls must be relatively lightly loaded, otherwise they produce opposed flattened areas on the tubing, i.e. localized indentation. Even when lightly loaded, they tend to flatten the tubing at the softer end of the typical annealing ranges. In addition, the lightly-loaded flat sensing rolls respond to slight changes in tubing dimensions or localized wall thickness variations as occur within the tolerance ranges of production, thus giving false readings.

By virtue of producing an overall change in shape by utilizing the preferred concave surfaces sensing rolls having sloping shoulders 54, as shown, the sensing rolls 20 and 22 can be relatively more heavily loaded than in the case of flat rolls; that is, the forces F can be substantially greater. The concave surfaces and partial confinement serve to distribute the substantial applied forces F throughout the tubing wall. The advantageous result of these cooperating features is that the change in shape from round to oval is responsive to the amount of anneal in the tubing without significantly responding to any slight changes in tubing dimensions or localized wall thickness variations within normal tolerances of production.

In order to provide an advantageous multiplication of the slight downward travel or movement of the axis of roll 20 resulting from the oval deflection of the annealed tubing, the outer end 44 of the lever 32 is used as an indicator. A pointer 48 carried by the lever cooperates with an upright scale 50 having graduations which are calibrated to provide a measurement of the degree of anneal for a predetermined wall thickness and diameter of the tubing 10.

Following the sensing rolls 20 and 22, the tubing passes between another pair of circularizing rolls, one of which can be seen at 56 in FIG. 1. This second pair of circularizing rolls at 56 is similar in configuration to the first pair, as seen in FIG. 2, for changing the tubing shape back to circular.

In order to control the degree of anneal by regulating the input of energy into the annealer 12, a sensing gage or transducer 58 is mounted adjacent to the outer end 44 of the lever 32. This transducer may be any suitable electro-mechanical or pneumatic or fluid-actuated device for translating the movement of the lever end 44 into a control signal. The control signal may be provided by electrical current or pneumatic means or fluid pressure or fluid flow. In this example, the transducer 58 is a potentiometer having an actuator probe 60 in contact with the lever 32.

For matching the full scale deflection of this transducer 58 relative to the full range of movement of the lever 32, the transducer can be moved along its mounting 61 so as to be closer to or further from the outer lever end 44. When the desired position is determined for the transducer 58, it is clamped in place on its mounting 61.

Accordingly, the movement of the lever end 44 is translated into an electrical control signal. This signal is fed by the control lines 62 to a control unit 64 adjacent to the annealer station 12 for controlling the heat energy being fed into the annealer station in response to the control signal.

In this system, the annealer station 12 includes a closed housing 66 having a bushing 68 at its entrance for excluding entry of air. A reducing atmosphere is maintained within the housing by feeding in a reducing gas such as hydrogen through a supply line 70. Within the housing 66 is an induction heating coil 72 surrounding the continuously moving tubing 10, providing an active heating zone for the tubing.

The heating action applied by the coil 72 is intensive, such that if the copper tubing 10 were stopped accidentally for too long a period, it would quickly become melted. By virtue of this intensive heating action, the residence time in the active heating zone can be reduced to a very short time period of less than twelve seconds. Thus advantageously the apparatus, as shown, quickly reaches equilibrium upon start-up or whenever the sensing, measuring and control apparatus calls for a change in annealing heating.

The control unit 64 also includes a manual control knob 73, so that the operator by observing the position of the pointer 48 relative to the scale 50 can manually control or regulate the annealing operation.

The fast and accurate sensing, measuring and control apparatus provided by the sensing rolls 20, 22 acting through the multiplication lever system 30, and the transducer 58, coupled together with the intensive heating action of the annealer and short residence time therein, provide a substantially uniform degree of anneal along a long length of the tubing 10. The overall time cycle of the apparatus, as shown, is such that the sensing of the anneal of each increment of the tubing 10 occurs within thirty seconds of the time when such increment was annealed in the annealer 12, thereby providing close control of the degree of anneal.

From the annealer 66 the tubing passes through an opening in a partition 74 into the cooler housing 76 which also has a reducing atmosphere provided by gas supplied through a supply line 78. In the cooler, there is a liquid bath 80 (FIG. 4) of suitable cooling liquid, such as water. The water is recirculated so as to avoid absorption of atmospheric oxygen by a pump 82 connected through pipes 84 to liquid-agitating nozzles 86 (FIG. 4) directed into a tank 88 holding the bath 80.

In order to avoid contact of the liquid 80 with the longitudinal Weld region in the tubing 10, the tubing is oriented such that the weld is positioned above the surface of the liquid bath and preferably within 10 of the top center position, and the tubing is only half submerged in the bath 80. The reason to avoid contact of the liquid with the weld region is to avoid any possibility of liquid entry into the tubing, in case of a gap in the weld. To accomplish this semi-submersion, the ends of the tank 88 have semi-circular recesses 90 forming weirs through which the tubing passes. Liquid flowing out through the weirs drains along the inclined bottom of the housing 76 and then down through a recirculation pipe 92 back to the pump 82. There are several bafiles 94 suspended into the tank by adjustable mounts 96, with bushings 98 in the baflies to prevent the tubing 10 from deviating from a straight line. There are cut-out regions 99 in the bottom of each baffle to permit circulation of the liquid bath.

At the exit from the housing 76, there is another bush ing 100 to exclude the atmosphere.

The stabilizing rolls 16 and 18 each has a semi-circular groove 102 (FIG. 2) which precisely fits the tubing 10. The depth of these grooves 102 is nearly a semi-diameter such that the roll flanges almost touch, as seen in FIG. 2. Thus, the circular shape and position of the tubing is precisely controlled before the tubing enters the sensing rolls 20 and 22.

Among the advantages of the uniform degree of anneal provided is that a uniformly structured tubing product is produced having uniform ductility and uniform mechanical properties when finished. The annealing relieves stress in the tubing wall. Moreover, the annealing reduces the amount of pull required in any subsequent drawing operation which may be applied to the tubing. Also, the degree of anneal can be controlled accurately over a wide range, depending upon the final characteristics desired.

In the preferred operating range for copper tubing in which the wall thickness is less than one-tenth (10%) of the outside diameter (O.D.), there is used a line speed between 10 feet per minute and feet per minute, and then the maximum change in tubing diameter at the sensing roll faces in the direction of the applied forces F may be adjusted to be less than 25%. As a specific example within the preferred range, the following values have been found to be advantageous:

Tubing size: 0.640 of an inch O.D.

Wall thickness: 0.023 of an inch gage, being less than 4% of the 0D.

Alloy: Deoxidized low phosphorus copper Line speed: 40 feet per minute Temperature of tubing leaving annealing station: 500 C. Hardness before anneal (Rockwell UT):

(1) At weld area: 75 (2) Balance of tubing: 71 Hardness after anneal (Rockwell IST):

(1) At weld area: 62 (2) Balance of tubing: 63 Amount of deflection from zero setting at the temper before annealing to the temper occurring after annealing: 0.030 of an inch.

1 claim:

1. The method of measuring and controlling the con tinuous annealing of a long length of metal tubing having a generally circular shape as seen in cross section comprising the steps of passing the tubing longitudinally through an annealer heating station for heating it to produce an annealing thereof,

passing the heated tubing longitudinally through a cooling station to reduce its temperature, passing the annealed and cooled tubing longitudinally between opposed sensing rolls which are relatively movable toward and away from each other,

applying a predetermined force urging the sensing rolls toward each other to produce non-localized change in the shape of the tubing wall from its initial generally circular shape into ovalled configuration as seen in cross section with the extent of overall change in shape of the tubing wall between the rolls increasing with an increased degree of anneal in the tubing,

sensing the extent of relative movement of the rolls toward each other resulting from change in shape of the tubing as a whole to measure the degree of the anneal of the tubing, and

controlling the heating of the annealer station in response to the sensed movement of the rolls to provide a uniformly annealed tubing product.

2. The method of measuring and controlling the con tinuous annealing of a long length of metal tubing as claimed in claim 1, including the steps of making the extent of overall change in shape of the tubing wall into ovalled configuration substantially proportional to the degree of anneal throughout the range of operation by,

partially confining and supporting the wall of the tubing as it is being changed into an oval configuration by, providing sensing rolls having rolling surfaces which as seen in cross section are each concave for partially embracing the opposite sides of the tubing, and

providing shoulders on each measuring roll sloping toward similar shoulders on the opposed sensing roll, said shoulders sloping away tangentially from contact with the tubing.

3. The method of measuring and controlling the continuous annealing of a long length of metal tubing as claimed in claim 2, in which the tubing is copper having a wall thickness less than one-tenth the initial outside diameter of the tubing, and

the maximum change in the initial diameter of the tubing in the direction of the applied force in changing from circular to ovalled configuration is less than 25%.

4. The method of measuring and controlling the continuous annealing of a long length of metal tubing as claimed in claim 2, including the steps of passing the cooled tubing between circularizing calibrating rolls having grooves which are circular in configuration embracing substantially the entire perimeter of the tubing for assuring that it is uniformly circular before pasing the sensing rolls.

5. The method of measuring and controlling the continuous annealing of a long length of metal tubing as claimed in claim 1, wherein the tubing has a welded seam extending longitudinally therealong, including the steps of orienting the longitudinally travelling tubing with the welded seam within 10 of the top center position and passing the heated tubing through the cooling station with the welded seam within 10 of the top center position, and

cooling the heated tubing by quenching submerging only the lower half portion of the travelling tubing in a liquid bath in the cooling station to avoid entry of the liquid into the tubing through any defects in the welded seam.

6. The method of measuring and controlling the continuous annealing of a long length of metal tubing as claimed in claim 1, in which the tubing has an initial general rectangular polyhedral shape, and wherein the perimeter of the tubing is partially confined during said change in shape by secondary supporting surfaces to produce an overall change in the shape thereof.

7. The method of measuring and controlling the continuous annealing of a long length of metal tubing comprising the steps of passing the tubing longitudinally through an annealing station, for heating the tubing to anneal it, feeding heat energy into the tubing as it is passing through the annealing station at high heating rate such that the residence time of the tubing in the annealing station is less than twelve seconds,

thereafter immediately passing the heated annealed tubing longitudinally through a cooling station for cooling the tubing,

passing the annealed and cooled tubing between sensing rolls which are relatively movable toward and away from each other,

applying a predetermined force urging the sensing rolls toward each other, at the same time partially embracing the perimeter of the tubing to produce non-localized change in the shape of the tubing from a generally circular shape into an ovalled configuration as seen in cross section,

with the extent of the change of the diameter of the tubing as produced by the sensing rolls in the direction of the applied force being in proportion to the degree of anneal thereof,

sensing the extent of movement of the sensing rolls towards each other to measure the degree of anneal, and

utilizing the sensed movement to control the heating rate to thereby control the annealing of the tubing to provide a tubing product which has a substantially uniform degree of anneal along its length.

8. The method of measuring and controlling the continuous annealing of a long length of metal tubing as claimed in claim 7, in which almost immediately after leaving the cooling station the tubing is passed between circularizing calibrating rollers confining substantially the entire perimeter of the tubing, and

almost immediately after passing between the circularizing calibrating rollers the tubing is passed between said sensing rolls,

by virtue of which the measuring of the degree of anneal occurs shortly after the fast annealing has taken place to maintain a uniform degree of anneal along the length of the tubing product.

'9. The method of measuring and controlling the continuous annealing of a long length of metal tubing as claimed in claim 8-, wherein the tubing has been fabricated by longitudinally welding metal strip, including the additional steps of orienting the tubing with the longitudinal weld region positioned with 10 of the top center of the tubing, semi-submerging the tubing in a liquid bath in the cooling station for rapidly cooling the tubing while avoiding liquid contact wth the welded seam region, and

within less than thirty seconds after the passage of the tubing from the annealing station passing the respective increments of the tubing between the sensing rolls for providing fast and accurate sensing of the degree of anneal.

10. The method of measuring and controlling the continuous annealing of a long length of metal tubing comprising the steps of passing the tubing longitudinally through an active heating zone for heating the tubing to anneal it, feeding heat energy into the tubing as it is passing through the active heating zone at high heating rate such that the total residence time of the tubing in the active heating zone is less than twelve seconds,

passing the annealed and cooled tubing between sensing rolls one of which is movable toward and away from the other, said sensing rolls having concave rolling surfaces partially embracing the opposite sides of the tubing,

applying a predetermined force uring the movable sensing roll toward the other to slightly change the shape of the tubing as seen in cross section from a circular configuration into an oval configuration between the sensing rolls in proportion to the degree of anneal thereof,

utilizing a movement multiplying pivoted lever to provide a multiplication of the extent of movement of the axis of the movable roll as occasioned by the oval deflection of the tubing,

sensing the multiplied movement occurring at the outer end of the lever system to measure the degree of anneal, and

controlling the heating rate in the active heating zone to thereby control the annealing of the tubing to provide a tubing product which has a substantially uniform degree of anneal along its length.

11. Apparatus for measuring the degree of anneal of a long length of metal tubing being continuously annealed comprising stabilizing rolls defining a substantially circular opening adapted to have the tubing passed therethrough for precisely controlling the circular configuration of the tubing,

a pair of opposed sensing rolls relatively movable toward and away from each other and adapted to have the annealed tubing passed longitudinally between them after passing between the stabilizing rolls,

means for applying a predetermined force urging the sensing rolls toward each other for deflecting the Wall of the tubing into an oval configuration with the extent of deflection of the tubing wall from its initial circular configuration to oval configuration increasing with the degree of anneal,

a movable lever system connected to the sensing rolls and responsive to deflection by multiplying the relative travel of the roll axes with respect to each other, and

a graduated scale in cooperative association with the movable lever system for providing a measurement of the degree of anneal of the metal tubing as it passes between the sensing rolls.

12. Apparatus for measuring the degree of anneal of a long length of metal tubing being continuously annealed, as claimed in claim 11, in which:

one of the sensing rolls (preferably the lower one) has its axis fixed in position,

the other sensing rolls (the upper one) is carried by the movable lever system such that travel of the upper roll toward or away from the lower roll produces a multiplied travel of the lever system.

13. Apparatus for measuring the degree of anneal of a long length of metal tubing being continuously annealed, as claimed in claim 12, in which:

said lever system includes a lever member of the second class, said lever member having a fulcrum pivot fixed in position with one end of the lever member mounted upon said fulcrum pivot,

the upper sensing roll being mounted upon said lever member at an intermediate position along its length,

the outer end of the lever member opposite from said fulcrum pivot being free to move with a multiplied travel of the travel of the upper sensing roll toward and away from the lower sensing roll, and

a pointer on the outer end of the lever member in cooperating association with said graduated scale for measuring the degree of anneal of the tubing as it passes between the upper and lower sensing rolls.

14. Apparatus for measuring the degree of anneal of a long length of metal tubing being continuously annealed, as claimed in claim 13, in which:

weight means are included in the means for applying the predetermined force to the sensing rolls, and

adjustable means for attaching the weight means to the outer end of the lever member are provided adjustable in position along the length of the lever,

whereby the effect exerted by the weight means on the lever member is multiplied in providing the predetermined force applied to the sensing rolls and the predetermined force can conveniently be adjusted.

15. Apparatus for measuring the degree of anneal of a long length of metal tubing being continuously annealed, as claimed in claim 11, in which:

the rolling surfaces of each of said sensing rolls. are

concave as seen in cross section for partially embracing the opposite sides of the tubing,

whereby the extent of deflection of the tubing wall from circular configuration to oval configuration is made substantially directly proportional to the degree of anneal throughout the range of operation.

16. Apparatus for measuring the degree of anneal of a long length of metal tubing being continuously annealed, as claimed in claim 15, in which: the concave rolling surface of each sensing roll as seen in cross section is saddle shaped as defined by a generally circular bottom are with shoulders sloping tangentially away from opposite sides of the bottom are, these sloping shoulders each converging toward the corresponding shoulders on the other sensing roll.

17. Apparatus for measuring and controlling the continuous annealing of a long length of metal tubing comprising an annealer station for heating the tubing as it is passed longitudinally through the station,

control means for controlling the heat energy being supplied to the annealer station,

a cooler station for reducing the temperature of the heated tubing,

a pair of opposed sensing rolls relatively movable toward and away from each other adapted to have the annealed and cooled tubing passed longitudinally between them,

means for applying a predetermined force urging the sensing rolls toward each other for deflecting the wall of the tubing into an oval configuration by an amount of deflection which increases with the increasing degree of anneal of the tubing wall,

a movable lever system connected to the sensing rolls, said lever system moving in accordance with the extent of relative displacement of the roll axes toward and away from each other and provides a muiltiplied movement of said relative displacement, an

transducer means responsive to the multiplied movement of the lever system for producing a control signal in accordance thereto, said transducer means being connected to said control means for controlling lit the annealing in response to the degree of anneal in the tubing wall being sensed as it passes between said sensing rolls. 18. Apparatus for measuring and controlling the continuous annealing of a long length of metal tubing, as claimed in claim 17, in which:

said lever system includes a lever member movable about a fulcrum pivot, and having an outer end which is at a distance from said fulcrum pivot,

one of said sensing rolls has its axis fixed in position,

the other of said sensing rolls is mounted upon said lever member at a position such that the distance from the fulcrum pivot to the axis of said other sensing roll is less than the distance from the fulcrum pivot to said outer end of the lever member,

whereby said outer end of the lever provides the multiplied movement of the relative displacement of the axis of said other sensing roll,

said transducer means being responsive to the movement of said outer end, and

an adjustable mounting for said transducer means for adjusting the position of the transducer means relative to the outer end of the lever for matching the deflection of the transducer to the full range of movement of the lever member.

19. Apparatus for measuring and controlling the continuous annealing of a long length of metal tubing, as claimed in claim 18, in which:

said means for applying a predetermined force urging the sensing rolls toward each other comprises weight means, and

adjustable means for securing said weight means to the outer end of said lever member at a position which is adjustable along the length of said lever member.

References Cited UNITED STATES PATENTS CHARLES N. LOVELL, Primary Examiner US. Cl. X.R.