Process and apparatus for determining the variation of tensile stresses in cold-rolled strip over the width thereof

Claim 2

A process of determining the variation of the tensile stresses in cold-rolled strip over the width thereof, which comprises pulling said strip over two parallel supports, which are spaced in and extend transversely to the longitudinal direction of the strip, exciting each of a plurality of longitudinal zones of said strip between said supports to vibrate at its natural frequency by means which are out of contact with the strip, detecting the vibration of each of said longitudinal zones at its natural frequency by means which are out of contact with said strip, and generating signals which are representative of the frequency of said detected vibration of each of said longitudinal zones as a measure of the tensile stress in said longitudinal zone.

Claim 3

A process as set forth in claim 1, in which each of said longitudinal zones is subjected to impulse excitation and is subsequently allowed to vibrate freely at its natural frequency.

Claim 4

A process as set forth in claim 1, in which each of said longitudinal zones is subjected to an excitation having a constant amplitude and a frequency which varies within a range that includes the natural frequency of each longitudinal zone, and an amplitude rise of the vibration in each of said longitudinal zones is detected as an indication that the frequency at which said longitudinal zone is then excited is its natural frequency.

Claim 5

A process as set forth in claim 1, which comprises detecting the vibration in each of said longitudianl zones of said strip and exciting each of said longitudinal zones to vibrate at the frequency of said detected vibration to build up the amplitude thereof.

Claim 6

A process as set forth in claim 1, in which each of three longitudinal zones, consisting of two edge zones and one central zone, of said strip is excited between said supports to vibrate at its natural frequency by means which are out of contact with the strip and in such a manner that said edge zones are excited in alternation with said central zone.

Claim 7

A process as set forth in claim 1, in which each of a plurality of longitudinal zones of said strip between said supports is excited to vibrate at its natural frequency by means which are out of contact with the strip and in such a manner that only alternate ones of said length portions are thus excited in a first length portion of said strip between said supports and the remaining length portions are thus excited in a successive second length portion of said strip between said supports.

Claim 8

A process as set forth in claim 1, in which all of said longitudinal zones of said strip between said supports are simultaneously excited to vibrate in such a manner that adjacent ones of said longitudinal zones are excited at different frequencies.

Claim 9

Apparatus for determining the variation of the tensile stresses in cold-rolled strip over the width thereof, while said strip is moved by being pulled in its longitudinal direction on a predetermined path, which apparatus comprises two parallel supports which are spaced along and extend transversely to said path and adapted to engage said strip when the same moves on said path, a plurality of vibration exciters, which are disposed one beside the other between said supports and closely spaced from said path, each of said exciters being operable to excite an associated longitudinal zone of said strip to vibrate at its natural freqUency when said exciter is out of contact with said strip, a plurality of vibration receivers, which are disposed one behind the other between said supports and closely spaced from said path, each of said receivers being aligned with one of said exciters in the longitudinal direction of said path and adapted to detect a vibration in the associated longitudinal zone of said strip at its natural frequency when said receiver is out of contact with said strip, and a plurality of signal generators, each of which is connected to one of said signal receivers and operable to generate signals which are representative of the frequency of said detected vibrations of the associated longitudinal zone as a measure of the tensile stress in said longitudinal zone.

Claim 10

Apparatus for determining the variation of the tensile stresses in cold-rolled strip over the width thereof, while said strip is moved by being pulled in its longitudinal direction on a predetermined path, which apparatus comprises two parallel supports which are spaced along and extend transversely to said path and adapted to engage said strip when the same moves on said path, a plurality of vibration exciters, which are disposed one beside the other between said supports and closely spaced from said path, each of said exciters being operable to excite an associated longitudinal zone of said strip to vibrate at its natural freqUency when said exciter is out of contact with said strip, a plurality of vibration receivers, which are disposed one behind the other between said supports and closely spaced from said path, each of said receivers being aligned with one of said exciters in the longitudinal direction of said path and adapted to detect a vibration in the associated longitudinal zone of said strip at its natural frequency when said receiver is out of contact with said strip, and a plurality of signal generators, each of which is connected to one of said signal receivers and operable to generate signals which are representative of the frequency of said detected vibrations of the associated longitudinal zone as a measure of the tensile stress in said longitudinal zone.

Claim 11

Apparatus as set forth in claim 8, in which said supports consist of rollers.

Claim 12

Apparatus as set forth in claim 8, in which said vibration exciters are disposed approximately midway between said supports.

Claim 13

Apparatus as set forth in claim 8, in which at least one of said supports is adjustable along said path.

Claim 14

Apparatus as set forth in claim 8, in which said exciters are aligned transversely to said path, said receivers are aligned transversely to said path, and said exciters and receivers are mounted on a common measuring table.

Claim 15

Apparatus as set forth in claim 8, in which each of said exciters and each of said receivers is adjustable transversely to said path.

Claim 16

Apparatus as set forth in claim 8 for use with electrically conducting strip, in which each of said vibration exciters consist of an a.c. solenoid having pole pieces directed toward said path.

Claim 17

Apparatus as set forth in claim 8 for use with electrically conducting, non-ferromagnetic strip, in which each of said exciters comprises an a.c. solenoid having pole pieces directed toward said path, a d.c. source is provided, and said supports consist of rollers comprising electrically conducting means connected to said d.c. source and adapted to contact a strip moving on said path, said electrically conducting means comprising slip rings.

Claim 18

Apparatus as set forth in claim 15 in which each of said exciters comprises a pair of registering a.c. solenoids which are electrically connected in parallel and disposed on opposite sides of said path and have pole pieces directed toward said path, and those of said solenoids which are disposed on one side of said path are adapted to be moved further away from said path.

Claim 19

Apparatus as set forth in claim 8, which is operable to subject each of said longitudinal zones to impulse excitation and then to allow each zone to vibrate freely at its natural frequency, in which apparatus said supports consist of rollers comprising electrically conducting means adapted to contact a strip moving on said path, said electrically conducting means comprising slip rings, each of said exciters consists of a conducting bar which extends along said path approximately midway between said rollers, and a pulse generator is electrically connected to said conducting bars and to said slip rings.

Claim 20

Apparatus as set forth in claim 15, in which said electrically conducting means comprise a plurality of copper rings, which are spaced apart along said roller and electrically connected to said slip rings and adapted to contact said strip moving on said path, and each of said copper rings is aligned with one of said exciters in the longitudinal direction of said path.

Claim 21

Apparatus as set forth in claim 8, in which each of said exciters consists of a compressed-air nozzle comprising modulating means for modulating a stream of air flowing through the nozzle.

Claim 22

Apparatus as set forth in claim 19, in which said modulating means comprise vibratable diaphragms.

Claim 23

Apparatus as set forth in claim 8, in which said receivers are inductive receivers.

Claim 24

Apparatus as set forth in claim 8, in which said receivers are capacitive receivers.

Claim 25

Apparatus as set forth in claim 8, in which said receivers comprise microphones.

Claim 26

Apparatus as set forth in claim 8, in which each of said receivers comprises a photodetector and light-transmitting means are provided which are operable to direct a plurality of light beams onto respective ones of said longitudinal zones of said strip between said supports for reflection onto respective ones of said photodetectors.

Claim 27

Apparatus as set forth in claim 8, in which each of said exciters is preceded by an amplifier adapted to drive said exciter, and each of said receivers has an output connected by an amplitude limiter to the input of one of said amplifiers.

Claim 28

Apparatus as set forth in claim 25, in which a filter is connected between each amplitude limiter and the amplifier associated therewith.

Claim 29

Apparatus as set forth in claim 25, for use with electrically conducting strip, in which each of said exciters consists of a solenoid having pole pieces directed toward said path and provided with an a.c. winding and with a d.c. winding.

Claim 30

Apparatus as set forth in claim 8, in which a frequency generator is provided, which is operable at a frequency which varies within a range that includes the natural frequencies of all said longitudinal zones, said exciters are frequency-controlled by said frequency generator and operable to subject said longitudinal zones of said strip to an excitation having a constant amplitude, each of said receivers is succeeded by a signal generator which is arranged to generate a signal in response to a rise of the amplitude of the vibration of the associated longitudinal zone above a predetermined value, and a storage device is provided, which is adapted to receive said signal and in response thereto to store in association with the respective longitudinal zone an indication of the frequency at which the frequency generator is then operated.

Claim 31

Apparatus as set forth in claim 28, in which a filter is connected between each of said receivers and the succeeding signal generator.

Claim 32

Apparatus as set forth in claim 28, in which said signal generators are adjustable to vary said predetermined value.