US3676959A

US3676959A - Apparatus for repairing defects in metallic workpieces by automatic means

Info

Publication number: US3676959A
Application number: US50458A
Authority: US
Inventors: Freiderich M O Forster
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-09-13
Filing date: 1970-06-29
Publication date: 1972-07-18
Anticipated expiration: 1989-07-18
Also published as: FR2070644A5; DE1946510A1

Abstract

The present invention relates to means for repairing defects in metallic workpieces, such as billets, which means are controlled by stored defect responsive information provided during the nondestructive test process. The nondestructive test apparatus provides defect responsive signals which are recorded and stored by storage means and subsequently recalled from the storage means for actuating defect repair means, such as a grinding wheel, engaging the workpiece at the defect location.

Description

United States Patent Forster 51 July 18, 1972 [54] APPARATUS FOR REPAIRING 3,180,230 4/1965 Judd et a] ..324 37 x DEFECTS IN METALLIC WORKPIECES 3,262,123 7 1966 Crouch ..324/37 x BY AUTOMATIC MEANS 3,290,167 12/1966 Wood et al.

3,394,302 7/1968 Judd [72] Inventor: Freiderich M. 0. Forster, Grathwohl- 3 4 9 1 2 9 19 9 w fl ct strasse 4, Reuflmgem Germany 3,491,288 1 1970 Forster ..324 37 [22] FOREIGN PATENTS OR APPLICATIONS 21 I 1 App] 50 458 1,177,328 5 1968 Great Br1ta1n ..51 165 R Foreign Application Priority Data Sept. 13, 1969 Germany ..P 19 46 510.2

U.S.Cl ..51/165 R,5l/78,,90/11 R, 324/37 Int. Cl ..B24b 49/04 Field of Search ..51/165 R, 165.71, 165.72, 165.77, 51/74 R, 78; 324/37 References Cited UNITED STATES PATENTS 2/1971 Miller et a1. ..324/37 9/1958 B0ltz..... 8/1961 Lloyd ..324/37 Primary Examiner-Lester M. Swingle Atl0rneyErvir1 B. Steinberg [57] ABSTRACT The present invention relates to means for repairing defects in metallic workpieces, such as billets, which means are controlled by stored defect responsive information provided during the nondestructive test process. The nondestructive test apparatus provides defect responsive signals which are recorded and stored by storage means and subsequently recalled from the storage means for actuating defect repair means, such as a grinding wheel, engaging the workpiece at the defect location.

5 Claims, 6 Drawing Figures PATENTEDJUHBIQTZ 3.676959 SHEET 1 OF 5 FRIEDRICH M. O. FGRSTER INVENTOR.

PATENTEUJULIBIWZ 3.876359 SHEET 2 [1F 5 F l G 2 1 K 82 so 8 ]78 FRIEDRICH M. o. F'CSRSTER INVENTOR.

PATENTED JUL 1 8 I972 FIG. 30

SHEET 3 UF 5 FRIEDRICH M. o. Fb'RsTER INVENTOR.

PATENTEU JUU 8 B72 SHEET U [1F 5 FRIEDRICH M. o. FO'RsTER INVENTOR.

APPARATUS FOR REPAIRING DEFECTS IN METALLIC WORKPIECES BY AUTOMATIC MEANS This invention concerns an arrangement for repairing surface defects in a metallic workpiece for the purpose of preparing the workpiece for further processing and to produce therefrom an end product of high quality. As used in the context of this invention, the term defect" shall include, but not be limited to a crack, occlusion, inclusion, discontinuity and the like, the presence of which renders a workpiece unsuitable or less desirable for further processing, such as rolling or drawing, and which defect ultimately may result in a rejected end product, or one characterized by inferior quality. Moreover, the repair of defects shall include a means for operating on the location of a defect, and such repair being adapted to prevent, when the workpiece is processed further, a degradation of the quality or a defective end product due to a heretofore existing defect.

When manufacturing wire, for example, an inclusion extending over a relatively short distance is increased during the drawing process to several times its original length. Thus, as a workpiece during drawing is subjected to high stress, a crack of considerable length may be produced and such a defect may very likely decrease the quality of the wire or render the particular wire portion not useable.

Apparatus have become known in which current is passed through a ferromagnetic workpiece, such as a steel billet. A defect along the longitudinal axis of the workpiece causes magnetic leakage flux at the location of such defect. The leakage flux is transferred to a magnetic recording belt .which is brought into contact with the surface of the workpiece under test. A sensing device responsive to the magnetic field is disposed for scanning the surface of the belt and provides a defect responsive electrical signal which can be displayed on the screen of a cathode ray tube. This described arrangement is known as the magnetographic test method.

An apparatus of this type may be operated in such a manner that the width of the billet to be tested is divided into several zones, for instance four zones, and that a respective marking device is provided for each zone. Upon the discovery of a defeet, the respective marking device causes a mark to be affixed to the workpiece at the location of the defect. Such marking may be accomplished, for instance, by a spray nozzle which is energized to produce a painted line whose length corresponds to the length ofthe defect.

Moreover, there are apparatus in which the workpiece is fed through a coil which is excited with alternating current of suitable frequency. The electrical field causes eddy currents in the workpiece. The existence of a defect manifests itself as a particular effect upon the coil and the existence and size of such a defect can be ascertained. It is known further that such an apparatus may be combined with a marking device for affixing at the location of the defect a mark of predetermined size and the extent ofsuch mark can be made to correspond to the defect.

Further arrangements have been disclosed which make use of eddy current sensing devices which rotate about a workpiece as eddy currents are generated within the workpiece. Again, a defect within the workpiece is sensed by the probes and a marking device is actuated in response to a defect being sensed.

With the above described arrangements it has been possible to distinguish between large and small defects and decide whether the marked workpiece should be rejected, or whether the defect can be repaired or remedied by localized treatment. Such repair may be carried out somewhat later but must be done before a finished end product is provided. A defect may be repaired, for instance, by grinding the workpiece with a portable grinding wheel. To date, the repair of defects, known generally as cleaning, has been carried out mostly manually.

The described method of repairing a defect is afflicted with several shortcomings. Firstly, such cleaning constitutes an additional operation during fabrication and, being a manual process, requires considerable amount of time. For instance,

when cleaning steel billets, it may be necessary to clean consecutively four different sides and it will be necessary, therefore, to rotate the billet each time. A further disadvantage resides in the fact that the grinding installation usually is not located along the production line where the workpiece is fabricated, hence transportation problems arise. Also, the repair of the defect depends to a considerable extent on the worker and his diligence whether or not all marked locations are properly repaired. In many cases the defect is not apparent by visual observation and considerable judgment on the part of the worker is required in deciding the depth to which the repair must be extended.

The present invention is an outgrowth of the need for overcoming the described shortcomings. According to the present invention, an apparatus is described for the repair of defects in metallic workpieces, The apparatus comprises a nondestructive test arrangement having one or more test channels, each associated with a predetermined zone of the workpiece. The test arrangement is adapted to provide a defect responsive impulse when and for the duration that the size of a defect exceeds a predetermined limit. Each channel is coupled to the storage device for temporarily storing a defect responsive signal, the location of the signal in the storage device being correlated with the defect in the workpiece. A defect repair means is associated with each of the channels and coupled to be responsive to the signal condition of the storage device. The storage device is cyclically interrogated and upon the existence of a defect responsive signal, the repair means is actated to cause in an automatic manner the repair of the defect present in the workpiece.

It is not important which type of storage means is used. In the simplest embodiment, as will be explained by an example, if the defect is marked by applying paint upon the workpiece, the workpiece itself may constitute the storage means. In all cases when signal storage is used, the defect responsive signal is stored in digital form and the presence or absence of such a signal is used to indicate whether or not a defect above a predetermined level exists. Similarly, the type of the repair means is immaterial and the present invention permits the use of a great variety of repair means which may be used advantageously.

Also, the invention is not limited to a specific type of workpiece. For instance, the invention may be used advantageously for billets of rectangular, round or other cross-section.

The invention will be more clearly apparent by reference to the description in which:

FIG. 1 depicts an apparatus for the repair of defects in a billet using an electronic shift register as a storage means;

FIG. 2 depicts an apparatus for the repair of defects in a billet using a magnetic recording tape as a storage means;

FIGS. 3a and 3b depict an apparatus for the repair of defects in a billet using a magnetic recording tape as a storage means and enabling the repair of defects to be carried out sub- 7 sequently at a suitable time and place;

FIG. 4 depicts an apparatus for the repair of defects in a billet wherein the markings affixed to the billet are used as storage means, and

FIG. 5 depicts an apparatus for the repair of defects in a billet using a single grinding wheel for the removal of defects.

As shown in FIG. 1, the nondestructive test apparatus comprises a magnetographic device which is used for testing billets, see for instance U.S. Pat. No. 3,491,288 in the name of F. M. O. Forster, dated Jan. 20, 1970. A billet 2 to be tested is magnetized by electric current being passed therethroughlengthwise. Longitudinal cracks 4 within the billet 2 intersect the magnetic field 6 formed about the circumference of the billet and cause the existence of a magnetic stray field 8 at the tacted by the belt. In this manner there is provided a continuous recording of the defect responsive magnetic stray fields. As viewed in the direction of rotation of the magnetic belt 10, a scanning disk 16 is disposed to engage the entire width ofthe belt along the line 14 after the latters contact with the surface of the billet 2. A magnetic sensing means 18 for sensing the signals on the belt 10 is disposed on the periphery of the scanning disk 16 which is driven by a motor 17. An erasing means 34 is disposed so that signals stored on the rotating belt are erased prior to renewed contact of a belt portion with the surface of the billet, thus rendering the recording means suitable for recording the subsequent signals. The sensing means 18 is coupled via a contactless or rotating transformer 19 to a logic circuit 20 which amplifies the defect responsive signals, causes demodulation thereof and contains, moreover, in its output stage a trigger circuit which provides an output signal if the defect responsive signal exceeds a predetermined value. The output of the logic circuit 20 is coupled to the input of an electronic channel gate 21.

The scanning disk 16 is provided with four

permanent magnets

22, 23, 24 and 25 which cause a respective impulse to be generated by the stationary coil 27 as a respective magnet passes in front of the coil. The distance between the

magnets

22, 23, 24 and 25 is selected in such a manner that the distance between the respective magnets corresponds to the width of the

zones

30, 31, 32 and 33 into which the surface of the billet is divided. It is necessary, therefore, that the arrangement is such that the first permanent magnet 22 reaches the coil 27 at the very moment when the sensing means 18 is positioned adjacent the near edge of belt 10. This condition corresponds to the sensing ofa signal originating at the beginning of the zone and stored on the belt 10.

A signal generated by the coil 27 is amplified by the amplifier 28 and is used as a command signal coupled to the input 29 of the channel gate 21. The command signal 50 produced causes the channel gate to be positioned in such a condition that a signal received at the input 26 is coupled to the output 36.

If the sensing means 18 is positioned for receiving a signal from the belt 10 corresponding to the zone 31, the magnet 23 causes the coil 27 to receive a subsequent impulse, which signal after being amplified by the amplifier 28 causes actuation of the channel gate 21 and provides a circuit connection between the input 26 and the output 38.

Subsequent to the scanning of that portion of the recording belt 10 which corresponds to the last zone 33, at which time the input 26 of the channel gate 21 is coupled to the output 42, a new counting cycle is started so that the following impulse at the input 29 of the channel gate 21, signifying the start of a new scanning cycle, causes the input 26 to be coupled to the output 36.

In this manner the four

zones

30, 31, 32 and 33 are associated with the

outputs

36, 38, 40 and 42 of the channel gate 21 to form four test channels.

The

outputs

36, 38, 40 and 42 of the channel gate are coupled to storage means such as the four

storage channels

44, 46, 48 and 50. Each channel comprises a stepping or shift register. The registers contain a series of n serially coupled stages or positions which are adapted to store signals in binary form and which signals, in this instance, denote defect or no defect.

Corresponding to the translating motion of the billet 2, the stored information is stepped or shifted from position to position. The output position of each storage means (shift register) is coupled to a respective repair means 52, 54, 56 and 58. As viewed in the direction of motion'of the billet, the means adapted to cause the repair ofa defect are staggered in the

respective zones

30, 31, 32 and 33 by a predetermined distance with respect to the test location 60.

For the sake of simplicity, it is assumed that the distance between the test location 60 and the line 14 along the belt 10 is so short compared to the distance .4 between the test loca tion 60 and the location of the rearmost defect repair means 74 that it can be neglected. Moreover, it will be assumed that the distance A is divided into n divisions. A roller 62 driven by the moving billet 2 is provided at its periphery with permanent magnets 64 whose spacing from each other corresponds to the length of such divisions A/n. Opposite the permanent magnets there is disposed a stationary induction coil 66 which produces a pulse signal responsive to the translation of the billet by a division 14/11. The output of the induction coil 66 is connected to the command signal input of each storage means 44, 46, 48 and 50. In this manner, as disclosed heretofore, the stored information is shifted from position to position in synchronism with the motion of the billet by a distance A/n. Therefore, the defect information is shifted in step with the motion of the billet, or expressed in other terms, the defect information is shifted together with the moving defect and arrives at the location where the repair can be made concurrently with the defect. A signal corresponding to a defect disposed in the output position of a particular storage means caused operation of the associated repair means and the repair means remains actuated as long as such a signal is present. If a crack has a certain length and such length extends over several distance divisions A/n, the repair means remains actuated until a defect-free distance or division appears. As illustrated, the means for repairing defects may comprise grinding

wheels

68, 70, 72 and 74, each disposed above a respective zone of the billet 2. Upon receipt of a defect responsive output signal from .the storage means, a respective grinding wheel is activated and lowered upon the billet for repairing the defect.

If further storage means are provided which are responsive to other defect information, eg information corresponding to the defect depth, it will be possible to provide operation of the grinding wheel corresponding to the depth of the defect. In practice it has been found that a single depth setting is suffcient for a majority of cases.

Owing to the large dimension of the grinding wheels it is not possible to dispose these wheels side by side at the location of defect repair, rather they must be staggered along the length of billet motion. Thus, only the rearmost grinding means 58 is coupled to the last or n'" position of the associated shift register. The next-preceding grinding wheel is distanced forwardly by a multiple integer a of the division A/n and, in order that this last-mentioned wheel receives its actuating signal at the proper moment, it must be connected to the (n-a) position of the associated storage means. A similar condition must prevail for all of the other serially disposed grinding means.

In certain instances, billets are tested simultaneously along all four sides. It is readily possible then to provide for the defect repair on all four sides. In this latter example it will be necessary, of course, to dispose grinding wheels along the four billet sides using the disclosed method. Such an arrangement has the major advantage that the billet passes through the test apparatus in a single path and leaves the apparatus fully cleaned.

Itshould be understood that the magnetographic test apparatus used in the heretofore described embodiment may be replaced by another nondestructive test device, for instance eddy current by stray flux test means using either a rotating probe for round material or a reciprocating probe for rectangular or flat stock.

The above described invention is not limited to the use of a storage device in the form of a shift register. It may be advantageous, for instance, to use a track on a magnetic recording tape 88, see FIG. 2, for each of the

test channels

36, 38, 40 and 42.

In this example the defect responsive signal of each

test channel

36, 38, 40 or 42 is coupled to a

respective head

71, 73, 75 or 77 for recording the respective signals on a track of the magnetic tape 88. The tape 88 has a speed governed by the translational speed of the billet 2. The recording tape transport and the billet motion provided by roller 86 may be coupled to each other via entirely mechanical means. However, a Selsyn drive may be found suitable also. In both cases, it will not be necessary that the speed of the billet and that of the recording tape be identical, the only requirement being that they are in proportion. Assuming the h denotes a given distance of the billet, s denotes the corresponding distance along the recording tape, v denotes the speed of the billet, and v, the speed of the recording tape, then h'v, s'v,. A distance S separates the signal retrieving means or pickup heads 78, 80, 82 and 84 from the recording heads 71, 73, 75 and 77 associated with the tape 88. The pickup heads sense the recorded defect signals and actuate in response thereto the defect repair means 52, 54, 56 and 58. The distance S, is dependent upon the distance A which denotes the distance between the defect sensing location and the repair means. From the above formula it follows that S, A'v /v An interesting modification involving the use of a recording tape in conjunction with the present invention is shown in FIGS. 3a and 3b. This modification concerns the read-out of the defect responsive signals recorded on tape 88 at a selected time and place. To this end, the billet 2 and the tape 88 are transported together to another location, such as a cleaning installation, where the defects are repaired fully automatically. In order to proceed in accordance with this modification it will be necessary to provide a means for transporting the billet (not illustrated), a tape transport means 89 for the tape 88, pickup heads 78, 80, 82 and 84, and defect repair means 52, 54, S6 and 58. As described hereinabove, the speed of the tape over the roller 86 is controlled by the translational speed of the billet. The location of the defect repair means is governed by the above stated formula in an analogous manner.

Another interesting modification of the present invention is shown in FIG. 4 and uses the billet itself as the means for recording and storing the information. Similarly as above, the defects may then be repaired at a selected time and location. This modification obviates the need for a separate storage means. It is assumed that during the nondestructive testing process of the billet paint marking is applied to the billet in response to defects sensed. The paint marks denote the location of the defect and indicate that a defect exceeds a predetermined minimum value. Testing and marking may be carried out using a plurality of channels, for instance four channels corresponding to

zones

30, 31, 32 and 33 of the billet. The object tested, for example, may be once again the side 12 of the steel billet 2. Four light sensitive means, such as

photodiodes

90, 92, 94 and 96, are disposed along the direction of motion of the billet 2 above the side 12 of the billet to be cleaned, and one diode is associated with each

respective zone

30, 31, 32 or 33. A source of light 98 illuminates the surface portion-of the billet disposed opposite the photodiodes. If a paint mark is present, the respective photodiode receives the reflected light and provides an output signal. in order to exclude spurious light, the photodiodes may be provided with filters which preferably pass only reflected light originating from a paint mark. The output signals from the diodes are passed to

respective amplifiers

91, 93, 95 or 97, one amplifier for each diode, which in turn are connected to the means for providing for the repair of defects, the grinding wheel means 52, 54, S6 and 58. If a paint mark 100 appears underneath the photodiode 92, a short time delay is provided which corresponds to the transit time of the defect from the photodiode 92 to the grinding wheel 70 before the grinding wheel is activated. The grinding wheel remains energized so long as a paint mark is sensed underneath the photodiode.

Often there is a desire that the paint be not visible with the naked eye. In this case it will be possible to provide instead of a normally used paint an organic liquid of high volatility having dispersed therein fluorescent particles. An ultraviolet lamp is used then in place of the conventional lightsource 98. Moreover, spurious light may be excluded even further by using photosensitive means which have maximum spectral sensitivity in the ultraviolet energy spectrum..Additionally, ultraviolet light filters may be used in front of the photodiodes. The above description has dealt largely with the use of grinding means for repairing defects. However, the repair or cleaning may be accomplished also by other means, such as chiselling or milling. Heating of the defect location using a torch as known in welding is another method which may be used advantageously. In this example, the output of the storage means controls the gas flow and ignition. A very fast action is possible for repairing with a high degree of success even small defects despite a relatively rapid billet motion.

Plasma heating may be substituted for chemically fueled flames in order to obtain localized melting.

Finally, a further modification of the present invention is possible. In this modification a single defect repair means, such as a grinding wheel, is useable in conjunction with the defect responsive signals provided by a plurality of test channels. As seen for example by reference to FIG. 5, the defect information provided by a nondestructive testing apparatus having a plurality of test channels is available in the form of zoned paint markings associated with the respective channels, there being four zones on the face of the billet 2 as described previously. The defect repair means comprises a grinding wheel 102 which may be moved in a transverse direction across the billet to a respective test zone which corresponds with the width of the respective test channel. Furthermore, the grinding wheel may be reciprocated lengthwise along billet 2 to provide for the repair of defects located in a particular zone. The arrangement includes a carriage 126, a motive means 117 for moving the carriage along the billet, a set of four illuminating

means

112, 114, 116 and 118, one illuminating means for illuminating a

respective zone

30, 31, 32 and 33, four associated

photodiodes

104, 106, 108 and 110, all mounted to the carriage and disposed above the billet face. The lengthwise motion of the carriage is limited by a pair of

light gates

120 and 122 which are connected to an electronic control circuit 124 for controlling the motion of the motive means 117. The grinding wheel 102 is also mounted upon the carriage and is adapted to be moved across the face of the billet to the different z'ones responsive to the motion of the motive means 119 which is controlled by the control circuit 124 to which the illuminating means and photodiodes are coupled for controlling the position and actuation of the grinding wheel. When the motive means 117 controlling'the lengthwise motion of the carriage 126 is started, the grinding wheel 102 is disposed in the outermost left zone. The grinding wheel is coupled via the control circuit 124 to the diode associated with that respective zone, specifically in this case with the photodiode 104. When encountering the defect marking 128, the grinding wheel is actuated and cleans the defect location. As the carriage passes to the light gate 120, the longitudinal carriage motion is terminated, the transverse grinding wheel motion is initiated, and the carriage return motion prepared. The defect information received by the

photodiodes

106, 108 and 110 during the preceding longitudinal carriage motion is stored by the control circuit. Zones in which no defect was present are skipped during the transverse motion of the grinding wheel so that after the grinding wheel is positioned in a new zone and the carriage is returned in response to such positioning, only the next zone exhibiting a defect marking is being worked. When the carriage reaches the opposite end of its longitudinal travel the described procedure is repeated until all defects marked by paint on the respective billet face are repaired.

It will be apparent that there exist still further embodiments of this invention which have not been described. The above examples are merely illustrative of the advance achieved in the art by combining the nondestructive test method carried out on billets with automatic defect repair means.

What is claimed is:

1. An apparatus for repairing defects in a billet comprising:

A. means for subjecting a billet to translating motion and passing it sequentially past a magnetographic test device and a repair station spaced a predetermined distance from one another;

B. said magnetographic test device including:

1. magnetic recording means having an endless belt;

2. means for rolling said belt longitudinally along the surface of the billet as the billet is translated past said test device, said means for rolling causing a portion of said belt to be in contact with said surface, whereby magnetic stray fields responsive to defects in the billet manifest at said surface are recorded upon said belt;

. a rotatable scanning disk disposed to engage the width of said belt along a line transverse to the motion of the billet between said device and said station, said scanning disk being disposed to be in contact with a portion of said belt after such portion has been in contact with said surface;

4. motive means coupled for rotating said disk about its center; I

5. a sensing means disposed at the periphery of said disk for receiving signals responsive to the recorded stray fields on said belt as said sensing means passes over said belt;

C. means disposed for erasing the recordings on said belt after said belt has been scanned by said sensing means;

D. a shift register which includes an input means, an output means and a plurality ofserially coupled stages connected therebetween;

E. means coupling said sensing means to said input means of said shift register;

F. repair means adapted to operate, when actuated, on the billet disposed at said repair station and coupled to said output means, and

G. means responsive to the translational motion of the billet coupled to said shift register for providing a control signal which causes said stages to shift a received signal from said input means to said output means in step with the motion of a defect in the billet from said test device to said repair station for causing actuation of said repair means when such defect is disposed at said repair station.

2. An apparatus for repairing defects in a billet as set forth in claim I, said billet having at least one flat surface, said endless belt being in contact with said flat surface, and said repair means disposed to engage said flat surface.

3. An apparatus for repairing a defect in the surface of an elongate billet, said surface being divided into a plurality of parallel longitudinal zones comprising:

A. means for subjecting the billet to continuing translating motion for passing it sequentially past a magnetographic test device and a repair station spaced a predetermined distance from one another;

B. said magnetographic test device including:

1. magnetic recording means having an endless belt;

2. means for rolling said belt longitudinally along said surface of the billet as the billet is translated past said test device, said means for rolling causing a portion of said belt to be in contact with a transverse portion of said surface spanning said zones, whereby magnetic stray fields responsive to defects in the billet manifest at said surface portion are recorded upon said belt portion;

4. motive means coupled for rotating said disk about its center;

5. a sensing means disposed at the periphery of said disk for producing signals responsive to the recorded stray fields on said belt as said sensing means passes over said belt;

C. means disposed in proximity to said belt for erasing the recordings on said belt after said belt has been scanned by said sensing means;

D. a shift register which includes a plurality of channels corresponding to the quantity of zones, each channel being associated with a respective zone and havingan input means, an output means and a plurality of serially coupled stages connected between the respective input means and output means;

E. a gate means coupled to said shift register input means;

F. means coupling said sensing means to said gate means;

G. control means associated with said disk and coupled to said gate means to cause during rotation of said disk signals produced by said sensing means to be transferred to the respective channel which is associated with the zone having the defect which causes the existence ofsuch signal;

H. said repair station including a plurality of independently operable repair means, one for each of said zones, and each such repair means including means for actuating the associated repair means to cause the respective repair means to operate upon the surface portion of the billet of the associated zone;

1. means coupling each of said means for actuating to the output means of the associated channel, and

.1. further control means disposed for engaging the billet and coupled to each of said channels for providing a cyclic control signal corresponding to the translational motion of the billet for causing said stages to shift a received signal from the respective input means through the associated stages to the output means in step with the translating motion of the billet, to cause actuation of the respective repair means when a defect disposed in the respective zone of the billet as originally recorded by said belt is disposed for repair by such respective repair means.

4. An apparatus for repairing defects in a billet as set forth in claim 3, said repair means comprising grinding means, said grinding means being disposed in a staggered array in the respective zones, the longitudinal distance between two adjacent grinding means being the ratio ofa-A/n wherein:

a is a multiple integer of the ratio A/n; 1

A equals the distance between said belt and billet surface and the position of the rearmost grinding means;

n is the quantity of serially coupled stages of the register channel associated with the rearmost positioned grinding means and is equal also to a selected quantity of longitudinal distance increments of the billet into which the distance A is divided; and means causing said further control means to provide said cyclic control signal whenever the billet has moved by a distance increment A/n.

5. An apparatus for repairing defects in a billet as set forth in claim 3, and amplifier means including means coupled in circuit with said sensing means and said gate means for providing a signal to said gate means when a signal produced by said sensing means exceeds a predetermined value.

Claims

1. An apparatus for repairing defects in a billet comprising: A. means for subjecting a billet to translating motion and passing it sequentially past a magnetographic test device and a repair station spaced a predetermined distance from one another; B. said magnetographic test device including: 1. magnetic recording means having an endless belt; 2. means for rolling said belt longitudinally along the surface of the billet as the billet is translated past said test device, said means for rolling causing a portion of said belt to be in contact with said surface, whereby magnetic stray fields responsive to defects in the billet manifest at said surface are recorded upon said belt; 3. a rotatable scanning disk disposed to engage the width of said belt along a line transverse to the motion of the billet between said device and said station, said scanning disk being disposed to be in contact with a portion of said belt after such portion has been in contact with said surface; 4. motive means coupled for rotating said disk about its centEr; 5. a sensing means disposed at the periphery of said disk for receiving signals responsive to the recorded stray fields on said belt as said sensing means passes over said belt; C. means disposed for erasing the recordings on said belt after said belt has been scanned by said sensing means; D. a shift register which includes an input means, an output means and a plurality of serially coupled stages connected therebetween; E. means coupling said sensing means to said input means of said shift register; F. repair means adapted to operate, when actuated, on the billet disposed at said repair station and coupled to said output means, and G. means responsive to the translational motion of the billet coupled to said shift register for providing a control signal which causes said stages to shift a received signal from said input means to said output means in step with the motion of a defect in the billet from said test device to said repair station for causing actuation of said repair means when such defect is disposed at said repair station.

2. An apparatus for repairing defects in a billet as set forth in claim 1, said billet having at least one flat surface, said endless belt being in contact with said flat surface, and said repair means disposed to engage said flat surface.

3. An apparatus for repairing a defect in the surface of an elongate billet, said surface being divided into a plurality of parallel longitudinal zones comprising: A. means for subjecting the billet to continuing translating motion for passing it sequentially past a magnetographic test device and a repair station spaced a predetermined distance from one another; B. said magnetographic test device including:

3. a rotatable scanning disk disposed to engage the width of said belt along a line transverse to the motion of the billet between said device and said station, said scanning disk being disposed to be in contact with a portion of said belt after such portion has been in contact with said surface;

4. motive means coupled for rotating said disk about its centEr;

4. motive means coupled for rotating said disk about its center;

4. An apparatus for repairing defects in a billet as set forth in claim 3, said repair means comprising grinding means, said grinding means being disposed in a staggered array in the respective zones, the longitudinal distance between two adjacent grinding means being the ratio of a.A/n wherein: a is a multiple integer of the ratio A/n; A equals the distance between said belt and billet surface and the position of the rearmost grinding means; n is the quantity of serially coupled stages of the register channel associated with the rearmost positioned grinding means and is equal also to a selected quantity of longitudinal distance increments of the billet into which the distance A is divided; and means causing said further control means to provide said cyclic control signal whenever the billet has moved by a distance increment A/n.

5. a sensing means disposed at the periphery of said disk for producing signals responsive to the recorded stray fields on said belt as said sensing means passes over said belt; C. means disposed in proximity to said belt for erasing the recordings on said belt after said belt has been scanned by said sensing means; D. a shift register which includes a plurality of channels corresponding to the quantity of zones, each channel being associated with a respective zone and having an input means, an output means and a plurality of serially coupled stages connected between the respective input means and output means; E. a gate means coupled to said shift register input means; F. means coupling said sensing means to said gate means; G. control means associated with said disk and coupled to said gate means to cause during rotation of said disk signals produced by said sensing means to be transferred to the respective channel which is associated with the zone having the defect which causes the existence of such signal; H. said repair station including a plurality of independently operable repair means, one for each of said zones, and each such repair means including means for actuating the associated repair means to cause the respective repair means to operate upon the surface portion of the billet of the associated zone; I. means coupliNg each of said means for actuating to the output means of the associated channel, and J. further control means disposed for engaging the billet and coupled to each of said channels for providing a cyclic control signal corresponding to the translational motion of the billet for causing said stages to shift a received signal from the respective input means through the associated stages to the output means in step with the translating motion of the billet, to cause actuation of the respective repair means when a defect disposed in the respective zone of the billet as originally recorded by said belt is disposed for repair by such respective repair means.

5. a sensing means disposed at the periphery of said disk for receiving signals responsive to the recorded stray fields on said belt as said sensing means passes over said belt; C. means disposed for erasing the recordings on said belt after said belt has been scanned by said sensing means; D. a shift register which includes an input means, an output means and a plurality of serially coupled stages connected therebetween; E. means coupling said sensing means to said input means of said shift register; F. repair means adapted to operate, when actuated, on the billet disposed at said repair station and coupled to said output means, and G. means responsive to the translational motion of the billet coupled to said shift register for providing a control signal which causes said stages to shift a received signal from said input means to said output means in step with the motion of a defect in the billet from said test device to said repair station for causing actuation of said repair means when such defect is disposed at said repair station.