US3622140A

US3622140A - Continuous heat treating line

Info

Publication number: US3622140A
Application number: US7041A
Authority: US
Inventors: Crayton H Schwestka; Ronald W Scherer
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1970-01-30
Filing date: 1970-01-30
Publication date: 1971-11-23
Anticipated expiration: 1988-11-23
Also published as: CA956458A

Abstract

Continuous-strip annealing line includes a plurality of furnacetemperature sensors and a plurality of strip-temperature sensors spaced along the pass line. A device is also provided for sensing strip speed. The temperature and speed sensors are sequentially connected to recording means by a programmer, to produce side-byside profile records of furnace temperature, strip temperature, and strip speed. The profiles show the conditions undergone by an increment of strip as it traverses the furnace.

Description

United States Patent [72] Inventors Crlyton H. Schwestka Mlehlgan City; Ronald W. Scherer, La Porte. both oi Ind. Appl No. 7,041 Filed Jan. 30,1970 Patented Nov. 23, 1971 Assignee National Steel Corporation CONTINUOUS HEAT TREATING LINE [8 Claims, 3 Drawing Figs.

US. Cl 266/3 R, 73/34l, 73/3435, 346/33 R int. Cl C2 ld 9/56 Field of Search 266/3 R;

73/340, 34!, 342, 343.5, 355; 346/33 R. 33 TP, 34

{56] References Clted UNITED STATES PATENTS 3,065,466 I l/l962 Hickman 346/34 Primary Examiner-Gerald A. Dost Attorney-Shanley and ONeil ABSTRACT: Continuous-strip annealing line includes a plurality of furnace-temperature sensors and a plurality of striptemperature sensors spaced along the pass line. A device is also provided for sensing strip speed. The temperature and speed sensors are sequentially connected to recording means by a programmer, to produce side-by-side profile records of furnace temperature, strip temperature, and strip speed. The profiles show the conditions undergone by an increment of strip as it traverses the furnace.

PAIENTEBuuv 23 197i SHEET 1 OF 2 INVENTORS CRAYTON H SCHWESTKA RONALD W. SCHERER ATTORNEYS i s: @2551 ama;

GEBdS dlHlS PATENTEU B 23 ml 3,622,140

sum 2 or 2 CONTINUOUS HEAT TREATING LINE BACKGROUND OF THE INVENTION This invention pertains to metallurgical apparatus, and more particularly to continuous lines for annealing steel strip.

Continuous furnaces for heat-treating elongated metal workpieces, e.g. steel or other metal strip, must be operated with precision so that the heat-treated product will have the desired metallurgical properties. Hence, it is conventional to equip continuous annealing lines with a plurality of devices for recording furnace temperature and a plurality of devices which record strip temperature, for the plurality of heating zones within the furnace. Prior art control systems employing such a multiplicity of recording devices require that the furnace operators mentally correlate the individual fragments of information provided by the various sensing devices in order to comprehend the status of the overall heat-treating operation. This has not been successful, and primary reliance for determining whether annealing has been properly effected is on results of physical testing of the strip after heat treating is completed. Such after-the-fact testing is unsatisfactory because, if something has gone wrong in the annealing operation, it is not discovered until it is too late to take action to save the strip from being off-specification. Accordingly, a need exists for improved heat-treating lines which permit more rapid and effective control over the treating operation, and a main object of the invention is the fulfillment of this need.

Other objects of the invention will appear from the following detailed description, which, in connection with the accompanying drawings, discloses a preferred embodiment of the invention for purposes of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross-sectional view of a continuous annealing line embodying principles of the invention.

FIG. 2 schematically illustrates the recording system of the continuous line of FIG. 1.

FIG. 3 schematically depicts a profile record of the type produced by the system of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a steel strip is conducted through a continuous annealing furnace 12 by a plurality of rollers as at 14, 16. The rollers guide the strip along a pass line through furnace 12 in the direction of arrow 18. Furnace 12 has a plurality of heating zones generally indicated at 20, 22, 24, 26 and 28 respectively, in which the strip is successively preheated, soaked, slow-cooled, fast-cooled, and held at the various temperatures which make up an annealing cycle. In a typical annealing cycle the strip is preheated to l,200 F further heated to l,400 F. and held for at least 25 seconds, slow-cooled to l,200 F. in at least 60 seconds, then rapidly cooled to 850 F. and held for at least 20 seconds.

A plurality of furnace temperature sensors in the form of thermocouples are mounted in the furnace walls at locations spaced along the pass line. The thermocouples are indicated at 30, 32, 34, 36, 38, 42, 44, 50, 52, 54, 56, 58, 62, 66, and 70, respectively. Each thermocouple senses the temperature of the furnace at the location of the thermocouple. Also, a plurality of strip-temperature sensors in the form of radiation pyrometers are spaced along the pass line, interspersed with the thermocouples. Each pyrometer focuses on the strip through an aperture in the furnace wall, and senses the temperature of the strip at the location of the pyrometer. The

pyrometers are indicated at 40, 46, 48, 60, 64, 68, and 72,

of travel of the strip along the pass line. Strip speed sensing device 76 produces an electrical signal which is proportional to the speed of the strip.

A multiple-point electronic strip chart recorder 78, which can be of any suitable type, has recording elements including a print wheel 80 for producing a record of furnace temperature, a record of strip temperature, and a record of strip velocity. These records are graphically produced in response to the signals from the temperature and speed sensors by action of the print wheel upon a moving strip chart 82. The records are in the form of longitudinally compact profiles or graphs which outline in sharp relief the conditions undergone by an increment of strip as it passes through the furnace. The furnace temperature, strip temperature, and strip speed profiles are produced in vertically side-by-side relationship as shown in FIG. 3. In FIG. 3, the profiles extend generally from left to right and are side-by-side in a vertical direction, i.e., superposed as a result of having been produced on the same horizontal increment of strip chart 82. Chart 82 has separate scales for temperature and strip velocity as ordinates, and a time scale as abscissa.

In FIG. 3, print points of arbitrarily differing configuration are employed for the separate profiles. However, multicolor or numerical printing can be used to distinguish the print points for the separate profiles. In FIG. 3, print points indicated by the letter .r" indicate furnace temperature, and it can be seen that, as the strip moves through the furnace, it successively encounters regions of increasing temperature in the initial portion of the annealing cycle. The strip then enter: regions where the temperature holds constant for the soaking period, then decreases (first slowly and then rapidly), and then holds again at the terminal portion of the annealing cycle.

Print points indicated with small circles depict the temperature of the strip, and collectively define a profile which shows that the strip undergoes thennal changes which generally correspond to the thermal conditions successively encountered in the sequence of temperature zones. The print points which define the strip speed profile are indicated by dots, and it will be observed that the speed is illustrated as remaining constant throughout the passage of the increment of strip through the furnace, which is as preferred. In FIG. 3, solid, broken, and light chain lines have been used for purposes of this disclosure to connect the print points of the furnace temperature, strip temperature, and strip speed profiles respectively, to facilitate an understanding of the graph. Such lines can in fact be drawn on the strip chart if desired, but are not necessary in practice because, when sufficient print points are provided, the operators eye can visualize the respective profiles and their correlation to one another from the print points alone. More or fewer print points than illustrated can be employed. Fewer print preferred to sense the strip temperature only at selected, key

locations in the furnace. For example, in the illustrated embodiment, strip temperature is sensed once toward the end of the preheating portion of the cycle, twice during the soaking period, and again at the end of the slow cooling period. It is measured again during and at the end of the fast cooling period, and finally at the end of the terminal-holding portion of the cycle. If the strip temperature at the selected locations is correct for the particular cycle and, if the furnace temperature profile is correct for the cycle, the operator can be assured that annealing is being effected satisfactorily.

To produce the profile records of FIG. 3, the recording elements of the recorder are operatively connected to respond to the sensors by an electrically conductive control system which includes an automatic programmer or sequencer 84 (FIG. 2) and electrical circuitry. Programmer 84 is an electromechanical device including a selsyn transmitter 86 having an axial shaft 88 which is mechanically connected through speedreducing gearing in a gearbox 90 to an axial shaft 92 of roller 16. By virtue of this arrangement, shaft 88 of selsyn transmitter 86 rotates at a speed which is proportional to that of the rotational speed of the roller and thus is proportional to the linear speed of travel of the strip.

Transmitter 86 is electrically connected through conductors 94 to a selsyn receiver 96 having an axial shaft 98. Shaft 98 rotates in synchronism with shaft 88 of transmitter 86. Selsyn

devices

86, 96 permit disposition of shaft 98 at a convenient location remote from roller 16, but assure rotation of shaft 98 at a speed proportional to that of the roller and thus to the linear speed of strip 10.

Fixed to shaft 98 along its length is a series of cams, including

cams

100, 102, 104, 106, and 108. The periphery of each cam includes a recess into which a follower contact can drop to close a switch in a circuit from one of the temperature sensors to recorder 78. It will be appreciated that in practice there is one cam for each temperature sensor along the pass line, but that only a selected number of cams is shown in the simplified diagram of FIG. 2 for clarity in illustration. Shaft 98 rotates in the direction of arrow 110, and the recesses in the cams are sequentially positioned in a circumferential direction around the shalt axis to close circuits from the temperature sensors to recorder 78 in a sequence according to the location of the sensors along the pass line as sequentially encountered by each increment of strip.

A cam-follower contact of a switch 112 is positioned to drop into the recess in cam 100 immediately upon rotation of shaft 98 through a small angular increment after energization of the selsyn devices to initiate a programming cycle. When the follower contact drops into the recess in cam 100, switch 1 12 is closed to close a circuit including conductors 114 from signal output transducer 116 of thermocouple 30 to the measuring circuit of recorder 78. The measuring circuit causes print wheel 80 of recorder 78 to move in accordance with magnitude of the signal along the ordinates of strip chart 82 to the proper location and the wheel then automatically produces a print point on the chart. The print point made in response to thermocouple 30 is indicated at 30' in FIG. 3. As the strip moves on and shaft 98 continues to rotate through its programming cycle, the follower contact is lifted from the recess in cam 100 and opens switch 112 to open the circuit from thermocouple 30 to recorder 78. Strip chart 82 in recorder 78 moves in the direction of arrow 118 at a constant rate as the strip moves on through the furnace.

At the time that action of cam 100 closed the circuit from thermocouple 30 to recorder 78, a particular increment of strip was at the location of the thermocouple. With respect to other cams on shaft 98, the angular positions of the cam recesses around the axis of the shaft are correlated with the distance between temperature sensors along the strip pass line so that, as the particular strip increment successively arrives at the locations of the remaining temperature sensors, circuits from the temperature sensors to recorder 78 are sequentially closed for the print wheel to produce the spaced-apart print points which collectively define the temperature profiles of FIG. 3. For example, as the strip increment sequentially arrives at the locations of

thermocouples

32, 34, 36, and 38 (FIG. 1), the print wheel respectively produces the print points indicated at 32', 34', 36', and 38' in FIG. 3. Then, as the strip increment arrives at the location of pyrometer 40 (FIGS. 1,2), the follower contact of a switch 120 (FIG. 2) drops into the recess in cam 102 to close the switch, thereby closing a circuit including conductors 122 from current output transducer 124 of pyrometer 40 to recorder 78. In response to the signal from pyrometer 40, print wheel 80 produces a print point indicated at 40' (FIG. 3). As the strip increment moves on, the strip increment successively encounters thermocouples 42 and 44 (FIG. 1,2) and the follower contacts of switches 126, 128 (FIG. 2) successively drop into recesses in

cams

104, 106 respectively and close the switches. Closure of switch 126 closes a circuit including conductors 130 from signal output transducer 132 of thermocouple 42 to recorder 78, and print wheel 80 moves to produce print point 42' (FIG. 3). When the strip increment arrives at thermocouple 44 (FIG. 2), closure of switch 128 closes a circuit including conductors 134 from output transducer 136 of thermocouple 44 to recorder 78, and the print wheel produces print point 44' (FIG. 3).

As the strip increment moves along the pass line and encounters pyrometer 46 (FIG. 2), the follower contact of a switch 138 drops into a recess in cam 108 to close a circuit including conductors 140 from output transducer 142 of pyrometer 46 to recorder 78 so that the print wheel produces print point 46' (FIG. 3). As the strip increment moves on through the furnace, encountering successive temperature sensors, programmer 84 sequentially connects the sensors in the manner described hereinabove to the recorder so that the print wheel produces the remainder of the print points which, together with those already printed, collectively define the profiles of the furnace temperature and the strip temperature. The print points in FIG. 3 are indicated by primed reference numerals corresponding to the reference numerals of the sensor which caused them to be produced.

Shaft 98 (FIG. 2) also carries a cam 144 which includes a plurality of peripheral recesses. As the strip increment moves through the furnace and as shaft 98 rotates, periodically when the strip increment is between temperature sensing locations, the follower contact of a switch 146 drops into one of the recesses in cam 144 to close a circuit including conductors 148 from strip speed sensor 76 to recorder 78. Each time this circuit is closed, the print wheel produces a print point indicative of strip speed, as at 76' in FIG. 3, and the series of print points 76' thus produced collectively define the strip speed profile.

It will be appreciated that programmers or sequencers of types other than that described above can be used to sequentially connect the temperature and speed sensors to the recording elements of the recorder and, if desired, the programmer can in part be built into the recorder so that the sequential connections to the recording elements of the recorder are effected within the recorder structure.

Programmer 84 (FIG. 2) operates only when

selsyn devices

86, 96 are supplied with electrical power from a source 150 through conductors 152. Actuation of programmer 84 can be effected manually when desired by depression of a pushbutton switch 154 to energize the selsyn devices. Shaft 98 carries a control cam 156, and when shaft 98 rotates through a small angular increment, the follower contact of a switch 158 is lifted out of a recess in cam 156 to close the switch and thereby close a holding circuit including conductors 162 around pushbutton 154 so that the pushbutton can be released but the programmer remains energized ad proceeds through its cycle, which is completed upon one full revolution of shaft 98. At the end of the cycle, the follower contact of switch 158 again drops into the recess in cam 156, opening the switch and thereby opening the holding circuit to deenergize programmer 84 so that the programmer is automatically stopped at the end of its cycle.

Since it is desirable to have at least one profile record for each coil passed through the annealing line, provision is made for actuating programmer 84 upon entry of each new coil into the line. To this end, a photosensitive cell 164 is disposed at the entry end of the line, mounted over strip 10 in alignment with a light source 166 which is disposed below the strip and directs a beam of light upwardly toward cell 164. A hole 168 is provided in the leading end of each coil, adjacent the weld joint 170 between coils. The hole is produced by a suitable punch (not shown) included in the line front end equipment. When hole 168 arrives at photocell 164 and permits the light beam to pass from source 166 to photocell 164, the presence of the new coil is detected by the photocell. The photocell then closes a circuit from electrical source through conductors 167 to energize a solenoid 172, which responds by closing switch 174 and thereby closing the circuit to the selsyn devices to start a programming cycle.

For long coils, it may be desired to have a plurality of profile records made for the coil. Or, it may be desired to periodically check the operation of the annealing line. For either purpose, a timer 176 is provided for actuating programmer 841 at preselected time intervals. The time intervals desired are manually preselected on timer 176, and at expiration thereof, the timer closes a switch 178 to energize programmer 84 and start a programming cycle.

The temperature of each of the plurality of heating zones in the furnace is regulated by an automatic controller. For example, the temperature of the furnace zone in which lies thermocouple 30 is regulated by a controller 180. Similarly,

controllers

182, 184, 186 and 188 are provided for the zones at which are located pyrometer 40,

thermocouples

42, 44, and pyrometer 46, respectively. Each controller is operatively connected in a conventional manner to the heating elements of the furnace in the respective zone to maintain the temperature of the associated zone at a desired value which is manually set on the controller. The temperature sensors are respectively operatively connected to continuously send the signal indicative of the thermal conditions actually prevailing in the furnace to the controllers. For example, output transducer 116 of thermocouple 30 sends its control signal through a connection 181 to controller 180. Each controller includes a switch for closing a circuit from electrical source 189 through conductors 190 to a solenoid 192, the switches of the controllers being in parallel circuit relationship with one another. When any controller detects any substantial deviation of the actual temperature conditions in its zone from the controller setpoint temperature, the controller energizes solenoid 192 which closes a switch 194 to actuate programmer 84 to perform a programming cycle. For example, if controller 180 detects any substantial difference between the temperature which it is set to maintain and the temperature sensed by thermocouple 30, the controller closes switch 196 to energize solenoid 192 and initiate a profile cycle.

Strip speed sensor 76 is operatively connected to a controller 198 having a switch 200 connected in parallel with the switches in the temperature controllers. The controller is set to monitor for a desired strip speed, and whenever the actual strip speed as detected by speed sensor 76 deviates from the setpoint of controller 198, the controller closes switch 200 and energizes solenoid 192 to actuate programmer 84.

It will be observed that whenever a malfunction occurs in the line -to produce a deviation of furnace or strip temperature or strip speed from setpoint, programmer 84 is automatically actuated to produce a record which will immediately show the nature, extent and location of the malfunction.

Switches

154, 174, 178 and 194 are of the momentary-contact type, and are in parallel circuit relation with each other and with holding circuit switch 158. Hence, the holding circuit maintains programmer 84 energized for complete performance of a cycle irrespective of the source of energization of the programmer, and then automatically stops the programmer when the cycle is complete. This arrangement of the respective cycle-initiating switches provides automatic protective interlocking, because once a program cycle is initiated by any one of the switches, there can be no interference with the cycle by closure of any of the other switches.

Recorder 78 is energized with energization of the selsyn devices, and can be provided with time-and-date printing indicia for identifying the strip chart at the initiation of each cycle. As an altemative, if desired, recorder 78 can be connected to speed sensor 76 to provide a continuous record of strip speed at times when programmer 84 is not operating. Also, if it is desired to produce a profile record of a part of the annealing cycle instead of the entire cycle, this can be effected by provision of temperature sensors only at the furnace zones corresponding to the portions of the cycle desired to be recorded. For example, it may not be desired to record the early stages of the preheating portion of the annealing cycle, and in this event the temperature sensorsfirst encountered by the strip may be omitted.

A summary of the operation of the system is as follows: Programmer 84 is energized automatically by closure of switch 174 upon entry of a new coil into the line, by closure of switch 178 upon expiration of a preset time interval, or by closure of switch 194 upon detection of a deviation from setpoint of furnace temperature, strip temperature, or strip speed. Or, programmer 84 may be actuated manually by closure of pushbutton switch 154. Upon energization of the programmer, shaft 98 begins to rotate, closing holding circuit switch 158. The follower contact of switch 112 drops into the recess in cam 100, closing switch 112 to close the circuit between thermocouple 30 and recorder 78 to produce print point 30'. As the strip increment which was at the location of thennocouple 30 when print point 30' was made moves on through the furnace, shaft 98 continues to rotate in synchronism therewith. As the strip increment successively encounters the remaining temperature sensors, the sensors are sequentially connected by operation of the cams on shaft 98 and cooperating switch contacts to the recorder to cause the remaining print points to be made. Periodically, speed sensor 76 is connected to the recorder to provide a record of strip speed. The last print point 72' is made as the strip increment completes passage through the annealing cycle. After the last point is printed, shaft 98 completes rotation through 360 and returns to its starting position, when cam 156 opens holding circuit switch 158 to deenergize the programmer.

Apparatus according to the invention is highly advantageous. The apparatus automatically produces a record of furnace zone temperatures as a compact profile showing with respect to time and location the zone temperatures encountered by an increment of strip as it traverses the furnace. Also, an automatic record of strip temperature is produced, showing the temperatures attained by the strip increment at the various zones. These records, combined in one document as described in the foregoing, are valuable process control tools in themselves, and are even more advantageous when produced in combination with the record of strip velocity. The three records are in a compact form that can readily be interpreted as to zone or strip temperature at any point, traverse period between points, correlation of strip and zone temperatures with each other and with traverse periods, and influence of strip speed on the operation. The records show the conditions of the heat-treating operation in a graphic form which is susceptible of rapid interpretation. The profile records permit more rapid and effective control over the heat-treating operation than is possible with prior art systems. The records also aid in development of heat-treating cycles, and provide permanent reference data for reviewing the history of a given workpiece.

Although the invention has been described in connection with a preferred embodiment, modifications thereof can be made without departing from the principles of the invention. For example, the electromechanical print control system described above can be replaced by a computerized electronic system in which the temperature sensors are sequentially connected to the recorder measuring circuit by a programmer or sequencer in the form of a stepping switch which is built into the recorder. The measuring circuit positions the print wheel along the temperature scale in accordance with the temperature signals, as in the system described above. The electronic computer determines time increments between print points in response to input data from the strip speed sensor and to information indicative of the distances between temperature sensors. The distance information can be provided by poten tiometers which are adjusted to produce in the computer signals which are proportional to distances between successive temperature sensors. Such potentiometers are successively switched into the computer by the programmer as the programmer successively switches the corresponding temperature sensors into the recorder measuring circuit. The computer output signal is used to energize the print wheel to produce a print point at the proper location along the time scale of the moving chart, and then advance the programmer to the next position. The computer output signal can be passed through an integrator to produce a contact closure which energizes the print wheel at the proper time to produce the print point.

ln such a modified system, a record of strip speed can be produced by an event marker pen which draws a continuous line near the edge of the temperature profile chart. The pen is movable to either of two locations which are spaced-apart in a direction transverse to the time scale. The location of the pen depends upon whether its actuating solenoid is energized or deenergized. To operate the pen, the signal from the speed sensor is also transmitted to another integrator which produces a number of contact closures per unit time varying as a function of the strip speed signal. The contacts are connected to alternately energize and deenergize the event marker pen, thereby producing a series of pips in the continuous line. The frequency or number of pips from point to point along the time scale is indicative of strip speed, it being only necessary to multiply such number of pips by a constant to obtain the speed of the strip. The value of the constant depends upon the function of the strip speed signal for which the integrator is adjusted.

The foregoing and other modifications within the scope of the appended claims are within the contemplation of the invention. I

I claim:

1. Metallurgical apparatus, comprising a continuous heat-treating furnace,

means for conducting an elongated workpiece along a pass line through the furnace,

a plurality of fumace-temperature sensing means for sensing the furnace temperature at each of a plurality of locations spaced along the pass line,

a plurality of workpiece-temperature sensing means for sensing the workpiece temperature at each of a plurality of locations spaced along the pass line,

recording means for recording furnace temperature and workpiece temperature profiles in side-by-side relationship, and

connecting means for operatively connecting the furnacetemperature and workpiece-temperature sensing means to the recording means,

the connecting means including programming means for sequentially connecting each of the fumace-temperature and workpiece-temperature sensing means to the recording means.

2. The apparatus of claim 1,

the recording means including a strip chart, and

means for graphically depicting the furnace temperature and workpiece temperature profiles on the strip chart.

3. The apparatus of claim 1, including controller means operatively connected to at least one of the furnace-temperature sensing means for detecting furnace temperature deviation from a setpoint, and

means responsive to the controller means for actuating the programming means.

4. The apparatus of claim 3, including second controller means operatively connected to at least one of the workpiece-temperature sensing means for detecting workpiece temperature deviation from a setpoint, and

means responsive to the second controller means for actuating the programming means.

5. The apparatus of claim 1, including controller means operatively connected to at least one of the workpiece-temperature sensing means for detecting workpiece temperature deviation from a setpoint, and

means responsive to the controller means for actuating the programming means.

6. The apparatus of claim 1, including means for actuating the programming means at preselected time intervals.

7. The apparatus of claim 1, including manually operable means for actuating the programming means.

8. The apparatus of claim 1, including detector means for detecting entry of a workpiece into the furnace, and

means responsive to the detector means for actuating the programming means.

9. The apparatus of claim 1, including speed-sensing means for sensing speed of workpiece travel along the pass line,

the recording means being operatively connected to the speed-sensing means and operable for recording a workpiece speed profile in side-by-side relationship with the furnace temperature and workpiece temperature profiles,

the programming means including means for periodically connecting the speed-sensing means to the recording means in sequence with the fumace-temperature and workpiece-temperature sensing means.

10. The apparatus of claim 9,

the recording means including a strip chart, and

means for graphically depicting the furnace temperature, workpiece temperature and workpiece speed profiles on the strip chart.

11. The apparatus of claim 9, including controller means operatively connected to the speedsensing means for detecting workpiece speed deviation from a setpoint, and

means responsive to the controller means for actuating the programming means.

12. The apparatus of claim 1 1, including second controller means operatively connected to at least one of the workpiece-temperature sensing means for detecting workpiece temperature deviation from a setpoint,

means responsive to the second controller means for actuating the programming means,

third controller means operatively connected to at least one of the furnace-temperature sensing means for detecting furnace temperature deviation from a setpoint, and

means responsive to the third controller means for actuating the programming means.

13. The apparatus of claim 12, including means for actuating the programming means at preselected time intervals.

14. The apparatus of claim 12, including manually operable means for actuating the programming means.

15. The apparatus of claim 12, including detector means for detecting entry of a workpiece into the furnace, and

means responsive to the detector means for actuating the programming means.

16. The apparatus of claim 9,

the recording means including a strip chart movable in a first direction, and

printing means for graphically depicting the furnace temperature, workpiece temperature and workpiece speed profiles on the strip chart,

the printing means being movable in a second direction transverse to the first direction and operable to produce a sequence of print points spaced along the first direction and defining the furnace temperature, workpiece temperature and workpiece speed profiles,

the programming means including means for connecting the fumace-temperature and workpiece-temperature sensing means to the recording means in a sequence corresponding to the sequence of location of the fumace-temperature and workpiece-temperature sensing means along the pass line,

the print points for the furnace temperature, workpiece temperature and workpiece speed profiles having differing visual characteristics,

the profiles extending in a first direction and being superposed in the second direction.

17. The apparatus of claim 1,

the recording means including a chart, and

printing means for graphically depicting the furnace temperature and workpiece temperature profiles on the chart,

temperature sensing means being interspersed along the pass line,

the programming means including means for connecting the fumace-temperature and workpiece-temperature sensing means to the recording means in a sequence corresponding to the sequence of location of the fumace-temperature and workpiece-temperature sensing means along the pass line.

t t l I II

Claims

1. MetallurgIcal apparatus, comprising a continuous heat-treating furnace, means for conducting an elongated workpiece along a pass line through the furnace, a plurality of furnace-temperature sensing means for sensing the furnace temperature at each of a plurality of locations spaced along the pass line, a plurality of workpiece-temperature sensing means for sensing the workpiece temperature at each of a plurality of locations spaced along the pass line, recording means for recording furnace temperature and workpiece temperature profiles in side-by-side relationship, and connecting means for operatively connecting the furnacetemperature and workpiece-temperature sensing means to the recording means, the connecting means including programming means for sequentially connecting each of the furnace-temperature and workpiece-temperature sensing means to the recording means.

2. The apparatus of claim 1, the recording means including a strip chart, and means for graphically depicting the furnace temperature and workpiece temperature profiles on the strip chart.

3. The apparatus of claim 1, including controller means operatively connected to at least one of the furnace-temperature sensing means for detecting furnace temperature deviation from a setpoint, and means responsive to the controller means for actuating the programming means.

4. The apparatus of claim 3, including second controller means operatively connected to at least one of the workpiece-temperature sensing means for detecting workpiece temperature deviation from a setpoint, and means responsive to the second controller means for actuating the programming means.

5. The apparatus of claim 1, including controller means operatively connected to at least one of the workpiece-temperature sensing means for detecting workpiece temperature deviation from a setpoint, and means responsive to the controller means for actuating the programming means.

8. The apparatus of claim 1, including detector means for detecting entry of a workpiece into the furnace, and means responsive to the detector means for actuating the programming means.

9. The apparatus of claim 1, including speed-sensing means for sensing speed of workpiece travel along the pass line, the recording means being operatively connected to the speed-sensing means and operable for recording a workpiece speed profile in side-by-side relationship with the furnace temperature and workpiece temperature profiles, the programming means including means for periodically connecting the speed-sensing means to the recording means in sequence with the furnace-temperature and workpiece-temperature sensing means.

10. The apparatus of claim 9, the recording means including a strip chart, and means for graphically depicting the furnace temperature, workpiece temperature and workpiece speed profiles on the strip chart.

11. The apparatus of claim 9, including controller means operatively connected to the speed-sensing means for detecting workpiece speed deviation from a setpoint, and means responsive to the controller means for actuating the programming means.

12. The apparatus of claim 11, including second controller means operatively connected to at least one of the workpiece-temperature sensing means for detecting workpiece temperature deviation from a setpoint, means responsive to the second controller means for actuating the programming means, third controller means operatively connected to at least one of the furnace-temperature sensing means for detecting furnace temperature deviation from a setpoint, and means responsive to the third controller means for actuating the programming means.

15. The apparatus of claim 12, including detector means for detecting entry of a workpiece into the furnace, and means responsive to the detector means for actuating the programming means.

16. The apparatus of claim 9, the recording means including a strip chart movable in a first direction, and printing means for graphically depicting the furnace temperature, workpiece temperature and workpiece speed profiles on the strip chart, the printing means being movable in a second direction transverse to the first direction and operable to produce a sequence of print points spaced along the first direction and defining the furnace temperature, workpiece temperature and workpiece speed profiles, the programming means including means for connecting the furnace-temperature and workpiece-temperature sensing means to the recording means in a sequence corresponding to the sequence of location of the furnace-temperature and workpiece-temperature sensing means along the pass line, the print points for the furnace temperature, workpiece temperature and workpiece speed profiles having differing visual characteristics, the profiles extending in a first direction and being superposed in the second direction.

17. The apparatus of claim 1, the recording means including a chart, and printing means for graphically depicting the furnace temperature and workpiece temperature profiles on the chart, the printing means being operable to produce a sequence of print points spaced along a first direction on the chart and defining the furnace temperature and workpiece temperature profiles, the profiles extending in the first direction and being superposed in a second direction transverse to the first direction on the chart.

18. The apparatus of claim 1, the furnace-temperature sensing means and the workpiece-temperature sensing means being interspersed along the pass line, the programming means including means for connecting the furnace-temperature and workpiece-temperature sensing means to the recording means in a sequence corresponding to the sequence of location of the furnace-temperature and workpiece-temperature sensing means along the pass line.