US3138048A

US3138048A - Classification of sheet material

Info

Publication number: US3138048A
Authority: US
Inventors: Gladden W Warren
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1963-09-24
Filing date: 1963-09-24
Publication date: 1964-06-23
Anticipated expiration: 1981-06-23

Description

June 23, 1964 G. w. WARREN CLASSIFICATION OF swam MATERIAL 3 Sheets-Sheet 1 Original Filed Feb.

N i L INVENTOR t SEES T 1 2m 553: NM! $5.253 :8 :35

WA RREN ATTORNEYS June 23, 1964 1 5. w. WARREN 3,138,048

CLASSIFICATION OF SHEET MATERIAL Y Original Filed Feb. 24, 1956 3 Sheets-Sheet 2 in 5g I .L 6/ T [in FIG 3 BY W ATTORNEYS J1me 1954 G. w. WARREN 3,138,048

-CLASSIFICATION OF SHEET MATERIAL VOL T 4 GE saunas INVENTOR 01.40;? ARREN BY MW 1 Q &- 5

ATTORNEYS United States Patent 3,138,048 CLASSIFICATION 0F SHEET MATERIAL Gladden W. Warren, Weirton, W. Va., assignor to National Steel Corporation, a corporation of Delaware Continuation of application Ser. No. 567,592, Feb. 24, 1956. This application Sept. 24, 1963, Ser. No. 315,734 19 Ciairns. (Ci. 83-406) This invention relates to improvements in classification of sheet material. More particularly the present invention relates to an improved apparatus for segregating prime sheets from defective sheets in an arrangement in which the sheets are sheared from continuous strip material.

Sheet material, such as light-gage steel sheets, are formed from continuous strip material fed to a shearing line which functions to cut the strip material into sheets of predetermined length. The strip material is ordinarily provided in the form of a coil supported by an uncoiling device operable to unwind the strip material and feed the strip into the input of the shearing line which includes a shear device for forming the sheets. Generally, a shear device of the rotating type is employed, and the length of the sheets produced is a function of the linear speed of the strip material and the speed of rotation of the shear device, the shear device usually being designed to produce one sheet per revolution. Conveyor means are located at the output of the shear device for receiving the sheets and for conducting the sheets to a suitable receiver. The conveyor means may be operated at a speed greater than the linear speed of the strip material to space. adjacent ends of the sheets leaving the shear device.

In practically every instance of production of sheet material, the sheets must meet certain standards. For example, in the production of sheets of light gage steel, the sheets must meet certain thickness requirements and must be free from pin holes, that is holes extending through the thickness of the sheets. Also, in cases of producing sheet material from coated strip, such as tinplated steel strip, the coating must be free from blemishes and other imperfections. The prior art includes numerous arrangements for detecting specific characteristics or imperfections of sheet material and for segregating prime sheets from those sheets which include imperfections or which do not meet certain physical requirements. It has not proven practical to scan the sheets leaving the shear device in order to segregate prime sheets from defective sheets, and in lines where sheet material is formed from continuous strip material the scanning or detection operation must necessarily take place upon the strip material on the input side of the shear device. This requirement presents a major problem of controllably delaying signals indicative of defects in subsequently formed sheets until sheets including defects reach a point in the line where the defective or non-prime sheets may be diverted by gate means from the normal path of the sheets and thereby segregated from the prime sheets. Since the gate means for diverting defective sheets from the normal path of the sheets must be operated in predetermined fixed time relation with respect to the leading edge of a defective sheet, and since a signal indication of a defective sheet may be located at any point along the length of a defective sheet, it is not possible to merely delay the detector signal in accordance with the strip speed and operate the gate means to singularly reject defective sheets.

The foregoing will be more fully understood by considering the specific problem of detecting pin holes in sheet metal material. In arrangements for accomplishing this operation, a photoelectric cell type of detector is 3,138,048 Patented June 23, 1964 Ice provided which produces a signal indicative of the presence of a pin hole. The detector is located ahead of the shear device and is positioned to scan strip material continuously fed into the shear line. When a portion of strip material including a pin hole passes the detector, a signal is generated indicative of such pin hole and the signal may be delayed for a time interval corresponding to the time required for the detected pin hole to reach the input of a deflector gate means. However, as the pin hole may be located at any point along the length of the sheet it is not possible to operate the gate means responsively to the time location of the pin hole and singularly reject defective sheets in high speed lines. In addition to the foregoing, arrangements provided by the prior art have the further disadvantage that they are not responsive to all pin holes or other defects in the strip material. This results from the fact that means provided for delaying the signals and operating the gate means requires a restoring time during which the arrangement is non-responsive to detected signals. It has been the practice in the past to solve these problems by operating the deflector gate means at a predetermined time interval following generation of a signal by the detector, and for maintaining the gate in an operative condition for a predetermined period of time to allow the defective sheet, the sheet preceding the defective sheet and the sheet following the defective sheet to pass through the deflector gate means. The pile of defective sheets are then visually examined and defective sheets are manually segregated from prime sheets. This inspection is not only time consuming and expensive but is undesirable since pin holes may be so small as not to be detected by visual inspection.

The present invention provides a novel arrangement operative responsively to detected signals, such as signals indicative of pin holes, for controlling a deflector gate in such a manner so that only sheets of material including imperfections, such as pin holes, are allowed to pass therethrough. Thus the present invention eliminates the necessity of rejecting two prime sheets for each defective sheet and the subsequent time consuming operation of visually inspecting and manually segregating prime sheets from defective sheets.

In accordance with the broad principles of the present invention, means are provided for converting a signal received from a detector, such as a pin hole detector, from a condition indicative of the relationship of the pin hole relative to the strip material to a condition in which the signal is indicative of a sheet portion of the strip material including the defect. The signal is then delayed for the proper period of time to cause deflector gate means to \operate in proper relationship with the leading edge of a sheet subsequently formed from the defective sheet portion to reject only the defective sheet.

The foregoing will be more fully understood from the following detailed description considered in connection with the accompanying drawings which disclose several embodiments of the invention. It is to be expressly understood, however, that the drawings are designed for purposes of illustration only and not as a definition of the lirm'ts of the invention, reference for this purpose being had to the appended claims.

In the drawings, in which similar reference characters denote similar elements throughout the several views:

FIG. 1 is a diagrammatic illustration of a novel sheet classifier embodying the principles of the present invention, the sheet classifier being shown in the environment of pin hole detection of continuous strip material subsequently sheared into sheets;

FIG. 1a is an end view of a portion of FIG. 1;

FIG. 2 is an enlarged fragmentary view, in cross-section, of a portion of the sheet classifier shown in FIG. la;

FIG. 3 is a diagrammatic showing of the novel electrical circuit included in the sheet classifier of FIG. 1;

FIG. 4 is an enlarged fragmentary view of a portion of the apparatus provided by the present invention; and

FIG. 5 is a diagrammatic illustration of another embodiment of the invention.

The present invention is disclosed in FIGURE 1 of the drawings in connection with a shear line for producing sheets from continuous strip material. A coil of strip material is located at the input of the shear line and is supported by suitable uncoiling mechanism of convenentional construction, not shown in the drawings. From the coil 10 the strip material 11 may pass through edging cutters 12 and roller levelers 13 to the input of a shear device 14 of the rotatable type. Suitable conveyor means, not shown, are provided for transferring the strip material from the coil to the shear device. The rotary shear device 14 is shown diagrammatically as including a pair of

rotary members

15 and 16, respectively, located above and below the path of the strip material 11. Each of the rotary members carries a cutting blade 17, and the cutting blades are angularly positioned so that upon rotation of the members at the same speed one sheet is cut upon each complete revolution. It is common practice to operate the shear device so that the cutting blades move at a speed corresponding substantially to the linear speed of the strip material, and also to drive the

rotary members

15 and 16 by means of elliptical gearing to obtain smoother operation.

Conveyors

18 and 19, which may be of the belt type, are located on the output side of the shear device. These conveyors may be operated at a speed greater than the linear speed of the strip material 11 to space the sheets 20 cut by the shear device, as shown. The conveyors are spaced from each other and a deflector or reject gate 21 is located therebetween. A container 22 for prime sheets is provided at the discharge end of the conveyor 19, and a container 23 for defective sheets is located beneath the deflector gate at the discharge end of the conveyor 18. With the deflector gate 21 in its position shown in FIGURE 1, sheets 20 are moved by the

conveyors

18 and 19 to the right, as viewed in the drawing, and are discharged into the prime sheet container 22. However, upon the deflector gate 21 being rotated upwardly, sheets leaving the conveyor 18 are di rected downwardly into the defective sheet container 23.

The present invention is disclosed in the environment of a system for detecting pin holes in continuous strip ma terial fed to a shear line and for segregating sheets having pin holes from prime sheets. It is to be expressly understood, however, that the present invention has utility in connection with other forms of systems, such as systems including gages for determining sheet thickness and means for segregating off-gage sheets from on-gage sheets, for example. As shown in FIGURE 1, a pin hole detector 25 of conventional construction is located at the input of the shear line for scanning strip material on its Way to the shear device. The pin hole detector includes a light source 26 located on one side of the path of the strip material and a photoelectric type sensing means 27 located on the other side of the path of the strip material. The photoelectric sensing means produces an output signal responsively to the presence of a pin hole in the strip material passing through the detector, and the output signal is fed to a conventional electronic amplifier 28. The signal from the amplifier 2.8 is fed to a novel signal converter and storage-time delay device 30. Aswill be described more fully below, the device 30 functions to convert successive signals indicative of pin holes in the strip material into signals representative of successive portions of the strip material corresponding to a later formed sheet including such pin holes, and to produce output signals therefrom in precise phase relationship with respective sheets and delayed to effect operation of the deflector gate 21 at the proper time and for the proper interval to reject only the defective sheets.- The output 4 signals from the device 30 are fed to a control circuit 31 which energizes a gate operating mechanism 32 connected to the deflector gate 21 through linkage 33.

The signal converterand storage-time delay device 30 includes a cylindrical drum 35 which may be formed of electrical insulating material. The drum is rotatably mounted by means of a shaft 36 secured to the drum in concentric relation with its longitudinal axis and supported in suitable bearings, not shown. One end of the shaft is connected through a gear reduction 37 and a variable coupler 38 to the rotating member 16 of the shear device 14. With this arrangement, the drum 35 rotates in synchronism with the shear device at an integral multiple of the speed of the shear device as determined by the gear reduction. In the arrangement illuustrated, the gear reduction provides a 10 to 1 ratio and the drum rotates at one-tenth the shear speed. The variable coupler 38 is provided to establish and maintain precise phase relationship between the drum 35 and the shear cutting knives 17. The variable coupler is especially useful in maintaining the required phase relationship in cases when the shear device is driven by elliptical gears.

The drum 35 is provided with a plurality of coplanar longitudinally spaced

circumferential grooves

40, 41, 42, 43 and 44, shown more clearly in FIGURE 2. The

grooves

40, 41 and 44 receive a series A of conductive segments 45, a series B of conductive segments 46, and a series C of conductive segments 47, respectively. The

conductive segments

45, 46 and 47 are of equal arcuate length and the conductive segments of each series are equally spaced from each other by blocks of insulating material 48, the blocks of insulating material in each of the series being of equal arcuate' length. The grooves 42 and 43 each receive a continuous

annular band

49 and 50, respectively, of conductive material. As will appear more fully below, the series A and B of spaced conductive segments and the continuous conductive band 49 aid in converting'signals from the detector 25 and for storing and delaying the converted signals and for feeding the output signals to the control circuit 31, while the series C of spaced conductive segments and the continuous conductive band 50 function to control the operating period of the deflector gate 21. Also, as will be described below, the number of conductive segments comprising each of the series A, B and C is equal to the ratio established by the gear reduction 37, and the ratio is at least equal to the nearest whole number obtained by dividing the distance between the detector 25 and the deflector gate 21 by the length of the sheet of smallest dimension to be produced by the shear line.

As shown more particularly in FIGURE 3 of the drawings, the segments comprising the series of spaced con ductive segments A, B and C are positioned with corresponding segments of each series in exact phase relationship. In particular, each of the segments 45 of the series A are angularly positioned about the drum 35 in precisely the same manner as corresponding

segments

46 and 47 of the series B and C. Thus, the

segments

45, 46 or 47 of the series A, B and C are positioned so that the leading ends of the segments of one of the series and the leading ends of corresponding segments of the other series lie in common planes parallel to the longitudinal axis of the drum 35. Also, since the segments of each of the series are of equal arcuate length, the trailing ends of corresponding segments of each of the series lie in common planes parallel to the longitudinal axis of the drum. Furthermore, in accordance with the principles of the present invention, corresponding segments of the series are imprecise phase relationshisp with the cutting knives 17 of the shear device 14. In particular, with the

members

15 and 16 of the shear device rotated to locate the knives 17 in cutting position, the drum 35 is angularly positioned so that the leading edge of corresponding segments of the series A, B and C lie along an imaginary plane represented by line X'X of FIGURE 3,

70 at the time of occurrence of the signals. 'bodiment of the invention the unidirectional current de- Since the drum rotates at a fixed multiple of the shear speed, and since the number of segments of each series corresponds to such multiple, the arcuate lengths of the segments and spacers 48 are proportioned so that the leading ends of successive corresponding segments of the series will lie along the plane XX at the time the knives 17 of the shear device are in cutting position. The variable coupler 38 is operable to establish this synchronization. The required synchronization between the shear device and the drum may be obtained by aligning the leading edges of corresponding segments of the series with a mark on the shear member 16 identical with the position of the cutting knives when in shearing position. A longitudinal bore in the drum, in angular alignment with the leading edges of a set of corresponding segments of the series, may be provided as a means for sighting onto the mark on the shear member.

As shown in FIGURES 1, 2 and 3, the segments 45 of the series A are electrically connected to corresponding segments 46 of the series B through conductors each including a. unidirectional current device such as a rectifier 60, the rectifiers being connected in the circuit to allow current flow from the segments 45 to the corresponding segments 46. Also, the segments 46 of the series B are electrically connected to the conductive band 49 through energy storage devices, such as capacitances 61. The output of the amplifier 28 is applied across input brushes 70 and 71. The brush 70 is positioned to successively contact the segments 45 of the series A upon each complete revolution of the drum 35, and the brush 71 is mounted to continuously contact the conductive band 49. With this circuit arrangement, an output signal from the amplifier 28 is conducted through the brush 70, through one segment 45 of the series A then contacting the brush 70, through the rectifier 60 connected to the one segment 45 contacting the brush 70, and is stored in the condenser 61 connected to the corresponding segment 46 of the series B, the circuit being completed through the conductive band 49, and the brush 71 connected to ground potential. It is to be expressly understood that the output from the amplifier 23 occurring during the period the input brush 70 contacts one of the segments 45 of the series A, which may comprise one signal or a group of signals, will be fed to the storage capacitance 61 connected to the corresponding segment of the series B. Also, the output from the amplifier 28 occurring at a later time when the input brush 70 is in electrical contact with a succeeding segment of the series A, will be stored in the capacitance connected to the corresponding succeeding segment of the series B. As shown in FIGURE 3, the input brush 70 has a dimension in the direction of rotation of the segments 45 substantially equal to the arcuate dimension of the insulating spacers 48. Thus, the input brush will terminate electrical contact with one of the segments 45 of the series A and establish electrical contact with the next successive segment of the series A substantially instantaneously.

Therefore. a series of time spaced output signals from the amplifier 28 will be stored in one or more of the storage capacitances 61 depending upon the position of the segments 45 of the series A relative to the input brush In this emvices 6%) are provided to prevent discharge of the voltage stored in the capacitance connected to one segment of the series A into the capacitance connected to the succeeding segment of the series A during the period in which the input brush 7t terminates electrical contact with one segment and establishing electrical contact with the next succeeding segment.

Output brushes 72 and 73 are provided to remove energy stored in the capacitances 61. The brush 72 is positioned relative to the drum 35 to electrically contact successively the segments 46 of the series B, while the brush 73 is mounted to continuously contact electrically the conductive band 49. As shown more clearly in FIG- URE 3, the brush 72 may have a dimension in the direction of rotation of the drum 35 less than the arcuate dimension of the insulating spacers 48 so that the brush 72 substantially terminates electrical contact with one of the segments 46 before the brush 72 initiates electrical contact with the next successive segment. Whenever the leading end of one of the segments 46 moves into electrical contact with the brush 72 any voltage stored in the capacitance connected to that segment is instantaneously developed across the

brushes

72 and 73. The

brushes

72 and 73 are connected by conductors 74 and 75 in parallel with an actuating coil 76 of an electromagnetic switch 77 included in the control circuit 31. The switch 77 is connected in the grid circuit of a gaseous electron discharge device 78 having a control grid 79 normally biased negatively by means of a connection to a voltage divider 80. However, upon closing of the switch 77 the control grid 79 is biased positively and the discharge device 78 fires when supplied with the required plate potential. Plate voltage for the discharge device 78 is supplied from a source 81 under control of the series C of segments 47. Each of the segments 47 are directly connected to the conductive band 50 through conductors S2. A brush 83 is mounted relative to the drum 35 to successively electrically contact the segments 47 upon rotation of the drum. This brush is connected through a conductor 84 to the source of plate voltage 81. The brush 83, as shown more clearly in FIGURE 3, includes a dimension in the direction of rotation of the drum slightly less than the arcuate dimension of the insulating spacers 48 so that the brush 83 terminates electrical contact with one of the segmentss 47 before establishing electrical contact with the next succeeding segment. A brush 85 is positioned relative to the drum 35 to continuously contact electrically the conductive band 50. A conductor 86 leads the brush 85 to the plate 87 of the discharge device 78 in series with an actuating coil 88 of an electromagnetic switch 39. With this arrangement whenever the switch 77 closes responsively to a voltage being developed across the

brushes

72 and 73, the control grid '79 is positively biased and the discharge device 78 fires since plate voltage is at that time supplied from the source 81 due to the phase relationship of the

brushes

72 and 83 as described below. The period of conduction of the discharge device 79 is determined by the length of the segments 47 and the speed of rotation of the drum 35, the discharge device 78 being extinguished upon the plate voltage dropping to Zero during transition of the brush 33 from one segment 47 to the next succeeding segment of the series C.

The gate operating mechanism 32 includes an armature 90 mounted for movement within actuating coils 91 and 92 and being connected to the linkage 33 for controlling operation of the deflector gate 21. The actuating coils 91 and 92 are wound in opposition and are energized from voltage source E under control of an electromag netic switch 93 having sets of contacts 94 and 95. The switch 93 is normally biased in the position shown, by means of a spring not illustrated in the drawing, to close the contacts 94 and connect the voltage source across the actuating coil 92. Upon energization the actuating coil 92 produces an electromagnetic force which moves the armature 9t downwardly to close the gate 21. The switch 93 is provided with an actuating coil 96 energized from the voltage source B through a circuit including the electromagnetic switch 89 of the control circuit 31. Upon closing of the switch 89 responsively to firing of the discharge device 73, the actuating coil 93 is energized to open contacts 94 and close contacts 95. This action energizes the coil 91 which effects upward movement of the armature 90 and opening of the reject gate. The reject gate remains open so long as current flows through the plate circuit of the discharge device 78 as determined by the time required for a segment 47 to move past the brush 83.

As mentioned above, corresponding segments of each ofthe series A, B and C are located in precise phase relationship relative to each other and the drum shaft 36 is coupled to the shear device 14 in such a manner so that whenever the shear knives 17 are in cutting position the leading ends of correspondnig segments of each series lie in a common plane passing through the longitudinal axis of the drum. In FIGURE 3 this plane is represented by line XX. Since one sheet is out upon each revolution of the shear device, and since the number of segments in each series is equal to the ratio established by the gear reduction 37, each segment of the series A, B and C is representative of a sheet portion of the strip material and a sheet formed from such sheet portion irrespective of the linear speed of strip material and of the length of the sheet. The pin hole detector 26 is located a fixed distance ahead of the shear device 14 and the reject gate 21 is located a fixed distance beyond the shear device. The distances between shear device and the pin hole detector and between the shear device and the reject gate may be converted, after the length of sheet to be cut is established, into a function of a number of sheets. Thus, the input brush 70 is located a number of segments ahead of the plane XX corresponding to the number of sheets that may exist between the detector and the shear device, and the brush 72 is located a number of segments after the plane XX corresponding to the number of sheets between the shear device and the reject gate 21. Since the segments of the series A, B and C are of constant length but are representative of sheets of variable length, as determined by the speed of the strip material and the speed of rotation of the shear device, it is necessary to adjust the relative positions of the brush 70 and the

brushes

72 and 83 with respect to the plane XX for different lengths of sheets cut by the shear device.

A simplified structure for adjusting the

brushes

70, 72 and 83 is shown in FIGURE 1 of the drawings. The brush 70 is supported by a U-shaped member 100 having the free ends of its legs rotatably mounted about the drum supporting shaft 36, while a U-shaped member 101, rotatably supported on the shaft 36 in a similar manner, supports the

brushes

72 and 83. The

brushes

70, 72 and 83 are supported by respective U-shaped members in such a manner as to rotate with the supporting members and yet maintain proper electrical contact with the segments of the series A, B and C. In one type of construction the U-shaped members may comprise blocks of insulating material provided with a series of openings to receive the brushes, the blocks being rotatable about the axes of the drum shaft and mounted with their inside surfaces in close proximity with the exterior surface of the drum. The

brush supporting members

100 and 101 are rigidly connected to control

gears

102 and 103, and the control gears are connected through

gear trains

104 and 105 to a common gear 106 rotatable by a control knob 107. The gear trains 104 and 105 may be designed so that upon rotation of the control knob in a clockwise direction the

brush supporting members

100 and 101 are moved toward each other, and upon rotation of the control knob in a counterclockwise direction the brush supporting members are moved away from each other. This performance adjusts the device 30 for operation with the particular length of sheets produced by the shear line. The control knob 107 may be calibrated with respect to the length of sheets, and in order to obtain a linear adjustment of the brushes the control gears 102 and 103, the

gear trains

104 and 105 and the common gear 106 may comprise elliptical gearing. The brushes '72 and 83 are supported by the U-shaped member 101 8 members and 101, they may be supported by the

members

100 and 101 if desired.

In the example shown in FIGURE 3 the detector 25 and the reject gate 21 are positioned relative to the shear device 14 and the shear line is operating to produce sheets 20 of such a length equal so that four sheets may exist between the detector 26 and the shear device 14 and three sheets may exist between the shear device and the reject gate. The control knob 107 is then rotated to position the input brush 70 four segments ahead of the plane XX, and the output brush 72 three segments after the plane X-X, the gearing between the control knob and the brush supporting members being designed in accordance with the positions of the detector and the reject gate relative to the shear device to provide the proper proportional movement of the

brushes

70 and 72. When the control knob is adjusted in accordance with the length of sheets being produced, the novel apparatus operates in the following manner: As the leading end of one of the segments 45 (referred to as the first segment) of the series A contacts the input brush 70, the leading edge of a sheet portion of the strip material, that is, that portion of the strip material comprising a subsequently formed sheet, enters the detector 25, and as the first segment is rotated past the input brush 70 and leaves contact with the input brush the sheet portion will pass through and will be scanned by the detector. Should a pin hole exist in any part of the sheet portion, the resulting signal will be amplified and fed to the input brush 70 and passed through the first segment and its associated rectifier to charge the storage capacitance 61 connected to the corresponding first segment of the series B. Since the corresponding first segment of the series B is representative of the sheet portion the charge on the capacitance connected thereto is representative of the sheet portion including the pin hole and the signal from the detector indicative of a pin hole in the strip material is thereby converted into a signal representative of a sheet portion having a pin hole. As the sheet portion having the pin hole moves from the detector towards the shear device 14, where it is cut into a sheet including the pin hole, and as the defective sheet moves toward the reject gate, its representative segment, the first segment of series B, moves across the plane XX and approaches the output brush 72. At the instant the leading end of the first segment of the series B contacts the output brush 72, the capacitance connected to the first segment of the series B is discharged through the actuating coil 76 to close the switch 77 and unblock the discharge device 78, and at the same instant the leading end of the corresponding first segment of the series C contacts the brush 83 to provide plate voltage for the discharge device. The gaseous discharge device thus fires and the current flow in its plate circuit effects closing the switch 89 with the result that the gate operating mechanism 32 funcions to open the reject gate 21. Since the first segment of the series B is representative of the sheet including the pin hole, the output signal developed across the

brushes

72 and 73, upon contact between the brush 72 and the leading end of the first segment of the series B, is in precise phase relation with the leading edge of the defective sheet irrespective of the location of the pin hole therein. Also, inasmuch as the input brush 70 and the output brush 72 are spaced from each other by a number of segments equal to the integral member of sheets that may exist between the detector and the reject gate, the output signal is developed across the

brushes

72 and 73 at the time the leading edge of the defective sheet approaches the reject gate. The reject gate remains open until the trailing end of the corresponding first segment of the series C leaves electrical contact with the brush 83 to terminate the supply of plate voltage and thereby extinguish the discharge device 78. When the discharge device 9. is extinguished, the switch 93 returns to its position shown in the drawing and the reject gate is moved to closed position. Since the corresponding first segment of the series C is also representative of the defective sheet, the reject gate will remain open for a suflicient interval to allow the defective sheet to pass therethrough, and will then move to closed position before the next sheet approaches the operating region of the reject gate. Inasmuch as the sheets 20 are spaced from each other delays in operation of the reject gate due to inertia of its moving parts does not interfere with its performance of singularly rejecting defective sheets. In some cases it may be desirable to cause the reject gate to open at a fixed interval ahead of the leading edge of a defective sheet. This adjustment may be accomplished by positioning the

brushes

72 and 83 slightly closer to the plane XX. In particular, in the example illustrated in FIGURE 3, instead of positioning the

brushes

72 and 83 three segments ahead of the plane XX, the brushes may be positioned two and one-half segments ahead of the plane XX to cause the reject gate to open one-half a sheet ahead of the defective sheet. The degree the reject gate is caused to operate ahead of the leading edge of the defective sheet may vary depending upon the type of reject gate employed and the one-half sheet lead is mentioned for exemplary purposes only.

After the first segment of the series A rotates past the input brush 70, the leading end of the next segment of the series A (referred to as the second segment) contacts the input brush at the time the leading edge of the next sheet portion enters the detector, and the second segment rotates past the input brush in synchronism with passing of the next sheet portion through the detector. Thereafter, successive segments of the series A will rotate past the input brush in synchronism with successive passing of respective sheet positions through the detector. Should a pin hole exist in the strip material, the indicative signal produced by the pin hole detector will be stored in the capacitance connected to the segment of the series B representative of the sheet portion including the pin hole to thereby convert the detector signal into a signal representative of the sheet portion including the pin hole. Since each of the series A, B and C include a number of segments at least equal to the maximum number of sheets that may exist in end-to-end relation between the detector and the reject gate (in the shear line for which the novel apparatus is designed for operation), the device 35 is operable to store all converted signals representative of sheet portions including pin holes until such converted signals are delayed for the time interval required to effect proper operation of the reject gate and reject their representative defective sheets. Furthermore, inasmuch as the input brush 70 is provided with a dimension in the direction of rotation of the segments 45 substantially equal to the arcuate dimension of the insulating spacers 48, the segments of each of the series A, B and C are effectively representative of the continuous strip material and the fact that the segments of each series are positioned in spaced end-to-end relationship does not create successive voids during which the apparatus would not be responsive to detected pin holes.

Pin holes that occur in light gage steel strip may be of microscopic size or may be quite large having dimensions along the length of the strip up to and exceeding A1, inch. Pin hole detectors presently available produce output signals which are substantially independent of the size of the pin hole detected, the signal being produced responsively to the leading portion of the pin hole. Therefore, in the event a substantially large pin hole, having a dimension along the length of the strip material equal to A inch, for example, is located in the strip material on both sides of a shear cutting line, part of the pin hole would be present in the trailing edge of one sheet portion and another part of the pin hole would be present in the leading edge of the succeeding sheet portion. In situations of this kind, the pin hole detector would produce a signal indicative of the part of the pin hole in the trailing edge of the first sheet portion and the resulting sheet would be deflected into the compartment 23 for defective sheets; however, the detector would not produce a signal indicative of the part of the pin hole in the leading edge of the succeeding sheet portion and the sheet formed from the succeeding sheet portion would pass into the container 22 for prime sheets. In order to overcome this problem the present invention provides a novel arrangement for automatically rejecting a defective sheet and the sheet succeeding the defective sheet when the detected pin hole is located in a predetermined marginal region of the trailing edge of the defective sheet. Such an arrangement insures rejection of all defective sheets irrespective of the size and location of the pin holes.

This feature of the invention, as shown in FIGURE 4, comprises a novel form of input brush including a pair of spaced contact elements 111 and 112 adapted to successively contact the segments 45 of the series A. The outside edges of the elements 111 and 112 are spaced from each other a distance greater than the arcuate dimension of the insulating spacers 48 so that the brush 110 simultaneously contacts the trailing edge of one segment and the leading edge of the succeeding segment as the segments 45 successively move past the brush 110. With this arrangement, when a signal from the detector occurs at a time when the brush 110 simultaneously contacts a pair of adjacent segments the capacitances connected to the corresponding segments of series B are charged with the result that the sheets formed from the sheet portions represented by the signals in the charged capacitances are caused to pass through the reject gate. The extent the outside edges of the elements 111 and 112 overlap the insulating spacers 48 determines the depth of the marginal edge at the trailing edge of the sheet portions in which the presence of a pin hole will automatically eifect rejection of the next succeeding sheet. Any desired depth of marginal edge may be established as required and the overlap provided by the brush 110 of FIGURE 4 is for the purpose of illustration only. The rectifiers 60 connected between the segments 45 of series A and corresponding segments 46 of the series B function to prevent discharge of previously charged capacitances into the capacitance connected to the next succeeding segment when the brush 110 simultaneously contacts adjacent segments.

With the segments 45 rotating in the direction indicated in the drawing, the outside edge of the element 111 comprises the trailing edge of the brush 110 and the brush 110 is positioned so that its trailing edge terminates electrical contact with the segments at the time the trail ing edge of sheet portions leave the detector. However, since the leading edge of the brush 110, i.e., the outside edge of the element 112, is spaced from the trailing edge of the brush a distance greater than the arcuate length of the insulating spacers 48, signals resulting from pin holes detected in the trailing marginal edge of the sheet portions will be passed to the capacitance representative of that sheet portion and also to the capacitance representative of the next succeeding sheet portion. Thus, the sheet formed from the sheet portion including the detected pin hole as well as the sheet formed from the succeeding sheet portion will pass through the reject gate providing the detected pin hole is located in the marginal trailing edge of the sheet portion as determined by the distance between the trailing and leading edges of the brush 110.

In the embodiment of the invention shown in FIGURE 5 of the drawings, strip material 120, supported by suitable conveyor means not shown, is passed through detector 121, such as a pin hole detector, to a shear device 122 whereby the strip material is formed into sheets, such as sheets 123.

Conveyors

124 and 125, spaced from each 11 other by a. stationary vane 126, provide a normal path for prime sheets. The conveyor 124 comprises an endless belt 127 supported by three rolls to present an inclined path 128 extending downwardly from the normal path toward the container 129 for defective sheets. A container 130 for prime sheets is located at the discharge end of the conveyor 125. A signal converter, storage and delay device includes a drum 131 rotatably supported on a shaft 132 driven by the shear device 122 through gear reduction, not shown, so that the drum rotates at an integral multiple of the shear speed in a manner similar to the arrangement of FIGURE 1. The drum 131 carries

similar series

133, 134, 135 and 136 of spaced conducting segments, the segments of each series being separated by insulating spacers 137. The drum 131 also carries a continuous conductive band 138. The conductive segments and the insulating spacers of each of the series 133, 134,

135 and 136 may be constructed in a manner similar to the series A, B and C shown in FIGURE 1. Corresponding segments of the series 135 and 136 are connected together through unidirectional current devices 139, and the segments of the series 136 are connected to the conductive band 138 through capacitors 141). Corresponding segments of the series 133 and 134 are interconnected by conductors 141. An input brush 142 is carried by a rotatable supporting member 143 and is positioned to successively contact the segments of the series 135 upon rotation of the drum 131. Output brushes 144 and 145 and reject gate control brushes 146 and 147 are carried by a rotatable supporting member 148 and are positioned to respectively contact the series of segments 136, the conductive band 138, the series of segments 133 and the series of segments 134. The

brush supporting members

143 and 148 may be adjustably rotated by a single control knob through gear trains in a manner similar to the arrangement of FIGURE 1.

The pin hole detector 121 includes a light source 151) positioned on one side of the path of the strip material and a photoelectric cell 151 positioned on the other side of the path of the strip material. When light impinges upon the photoelectric cell 151, due to the presence of a pin hole in the strip material passing through the detector 121, a positive pulse is transferred through resistor 152 to the control grid 153 of an electron discharge device 154 to overcome the normal blocking bias on the control grid and render the device conducting. The plate circuit of the device 154 is coupled through capacitance 155 to control grid 156 of a normally conducting electron discharge device 157. Thus, upon conduction of the device 154 a negative pulse is applied to the control grid 156 to block the discharge device 157. When the device 157 is rendered non-conducting, a positive pulse is applied through capacitance 158 and resistor 159 to control grid 160 of a gaseous discharge device 161, the gaseous discharge device being biased as to be ionized by the application of the positive pulse to its control grid. A coil 162 of an electromagnetic switch 163 and contact 164 of a normally closed electromagnetic switch 165 are serially connected in the plate circuit of the gaseous discharge device 161, and the plate of the gaseous discharge device is coupled through capacitance 166 to control grid 167 of a normally conducting electron discharge device 168, the plate circuit of the latter device including coil 169 of the electromagnetic switch 165. Upon firing of the gaseous discharge device 161, current flow in its plate circuit energizes the coil 162 to close contact 170 of the electromagnetic switch 163 and connect a source of relatively high voltage 171 to the input brush 142 by way of a conductor 172. Current flow in the plate circuit of the gaseous discharge device 161 also applies a negative pulse to the control grid 167 to block the discharge device 168 and efifect opening of the switch 165 and extinguishment of the gaseous discharge device 161 by terminating its plate voltage. The time constant of the capacitance 166 and the resistor 173 is selected to delay blocking of the discharge device 168 to allow adequate charging of the capacitance 141) connected in the circuit with the input brush 142.

When the drum 131 is rotated to move the leading end of a segment of'the series 136 into contact with the output brush 144, and if the capacitance connected to that segment is charged, a high voltage positive pulse will appear across the output brushes 144 and 145. This high voltage pulse is applied through a conductor 174 and a resistor 175 to control grid 176 of a gaseous electron discharge device 177. At the instant the output brush establishes contact with a segment of the series 136, the

brushes

146 and 147 make electrical contact with corresponding segments of the series 133 and 134 to thereby supply plate voltage to the gaseous discharge device 177 through a conductor 178 and a coil 179 of an electromagnetic switch 1181). Simultaneous supply of the plate voltage and application of the positive pulse to the control grid 176 fires the gaseous discharge device 177, and the resulting current flow in the plate circuit closes contact 181 of the electromagnetic switch 181). The switch 181) remains closed until the gaseous discharge device 177 is extinguished upon terminating its plate voltage. The latter action occurs when the corresponding segments of the series 133 and 134 lose contact with the

brushes

146 and 147. The electromagnetic switch 181) controls. operation of a high current switching device 182 provided for controlling the flow of current from source 183 to a magnetic reject gate 184. The current switching device 182 may comprise a pair of

gaseous discharge devices

185 and 186 which may be of the ignition type. The magnetic reject gate 184 includes a lower electromagnet 191) having a core 191 extending upwardly into close proximity with the normal path of the sheets and positioned forward of the stationary vane 126, and an upper electromagnet 192 having a downwardly depending core 193. The electromagnets are elongated and extend transversely of the path of the sheets between the end rolls of the conveyor 124. The electromagnet 192 is connected to the source 1 83 by way of conductors 188 and 194 and is continuously energized to produce an upward force on the sheets leaving the conveyor 124 which lifts the sheets upwardly so that they pass over the stationary vane 126. The electromagnet 191), when energized, produces a downward force on the sheets leaving the conveyor 124. The electromagnet 191) is designed to produce a downward force on the sheets greater than the continuous upward force produced by the electromagnet 192. With this arrangement, upon energization of the electromagnet 190, the sheets are moved downwardly to beneath the stationary vane 126 and onto the inclined conveyor 128. Energization of the electromagnet 191) is controlled by the high current switching device 182 responsively to the switch 181 The switching device 182 is connected between the source 183 and the electromagnet 191) by means of

conductors

187 and 189. Thus, during periods of conduction of the gaseous discharge device 177, the

electromagnet is energized to pull sheets below the of the drawings operates in a manner similar to the arrangement shown in FIGURE 1 to convert signals from the detector indicative of pin holes in the strip material into signals representative of sheet portions including the pin holes and to store converted signals and to produce output signals responsively to converted signals in precise phase relationship with the leading edge of sheets formed from sheet portions, of which the converted signals are representative, and delayed a required time interval to operate the reject gate and deflect respective sheets from the normal path of sheets leaving the shear device. The embodiment shown in FIGURE 5, however, includes novel features, not present in the FIGURE I arrangement, which improve the overall response time of the apparatus and provides a sheet classification system having a maximum speed of operation only limited by the operating speed of the reject gate. These advantages are obtained by the provision of a pulse forming a network for charging the capacitances 140 responsively to signals from the detector. The pulse forming network includes electron discharge devices 161 and 168 which function, when triggered, to apply a short duration high voltage pulse to the circuit of the input brush 142. A trigger circuit including

electron discharge devices

154 and 157 is employed to trigger the pulse forming network responsively to signals from the detector. The circuit elements of the pulse forming network and the trigger circuit have short time constants so that the high voltage pulse is applied to the input brush circuit substantially instantaneously upon the presence of a signal from the detector, and the duration of the high voltage pulse is relatively short so that the pulse forming network is rapidly conditioned to respond to successive signals from the detector. The high voltage pulses stored in the capacitances are employed to directly trigger the gaseous discharge device 177 which controls the energizing circuit of the reject gate. With this arrangement the reject gate is energized substantially instantaneously upon generation of the output signals across the

brushes

144 and 145. In FIGURE the output brushes 146 and 147 each contact a series of spaced conductive segments 133 and 134, respectively. The use of two series of spaced conductive segments make it possible to more accurately control the operating period of the reject gate 184.

Although several embodiments of the invention have been disclosed and described above, it is to be expressly understood that various changes and substitutions may be made therein without departing from the spirit of the invention as well understood by those skilled in the art. For example, the

drum

35 or 131 need not comprise a block of insulating material as previously described but may be constructed of non-insulating material and provided with means for insulating the conductive segments of each series from each other and from the segments of the other series as well as from the conductive bands. Also, other forms of time control means may be employed for returning the gate to closed position instead of utilizing the arrangements shown in FIGURES l and 5 in which one or more series of spaced conductive segments carried by the

drum

35 or 131 are employed for this purpose. For example, the

gaseous discharge devices

78 and 177 may be normally connected to a source of plate voltage through a control circuit including a normally conducting electron discharge device having a control grid coupled to the plate of the gaseous discharge device through a time delay circuit adjusted so that the electron discharge device of the control circuit is momentarily blocked a predetermined period of time after the gaseous discharge device is fired to allow a defective sheet to pass through the reject gate. Furthermore, it is contemplated by the present invention to utilize the signal converting, storing and delaying devices of FIGURES l and 5 for handling signals produced by detectors in addition to pin hole detectors, such as output signals from a thickness gage, for example. Moreover, it is within the scope of the present invention to utilize the signal converting, storage and delay devices of FIGURES 1 and 5 in connection with a plurality of detectors for producing signals indicative of different defects of strip material and for controlling operation of a plurality of reject gates, one for each type of defect for example. This may be accomplished by charging the capacitances to different voltages or to voltages of opposite polarity responsively to signals indicative of different defects in the strip material. Also, in the arrangement of FIGURES 1 and 3, the brush 83 may be adjusted to lead the output brush 72 in order to control the operative period of the reject gate. Reference therefore will be had to the appended claims for a definition of the limits of the invention.

This application is a continuation of patent applica- 14 tion Serial No. 567,592, filed February 24, 1956, now abandoned.

What is claimed is:

1. In a shear line for continuous strip material including a shear for cutting successive sheet portions of continuous strip material into sheets of predetermined length and deflector means operable to direct sheets along a predetermined path, the combination comprising detector means for detecting defects in the strip material on its way to the shear and producing signals indicative of such defects, a series of isolated energy storage means each indicative of a single sheet portion of the continuous strip material, means for successively coupling the detector means to isolated energy storage means of the series in synchronism with successive movement of sheet portions of the strip material relative to the detector means whereby signals from the detector means indicative of defects in sheet portions of the strip material are stored in separate isolated energy storage means, means for successively removing signals from isolated energy storage means in phase with a predetermined point along the length of sheets formed from respective sheet portions of the strip material and delayed to coincide with the time respective sheets approach the deflector means, and means for operating the deflector means responsively to removed signals.

2. In a shear line for continuous strip material including a shear for cutting successive sheet portions of continuous strip material into sheets of predetermined length and deflector means operable to direct sheets along a predetermined path, the combination comprising detector means positioned relative to the path of the strip material on its way to the shear detecting defects in the strip material and producing signals indicative of such defects, a series of spaced conductive members each indicative of a single sheet portion of the continuous strip material, an input brush mounted to successively contact the conductive members of the series upon relative movement between the input brush and the series of conductive members, means for feeding signals produced by the detector means to the input brush, an energy storage element connected to each conductive member of the series of conductive members, means for synchronizing relative movement between the input brush and the series of conductive members and movement of sheet portions relative to the detector means so that the input brush successively moves relative to the conductive members in synchronism with movement of sheet portions relative to the detector means, means for adjusting the phase of the relative movement of the input brush and the series of spaced conductive members and the movement of sheet portions relative to the detector means so that electrical contact is established between the input brush and the leading end of a conductive member at the time the leading edge of a sheet portion enters the detector means, and means for removing signals from the storage elements in synchronism with sheets formed from respective sheet portions which are delayed to operate the deflector means at the proper time to deflect defective sheets along the predetermined path.

3. The combination defined in claim 2 in which unidirectional current means are provided in the connection between each of the conductive members and the storage element connected thereto.

4. The combination defined in claim 3 in which the input brush has a dimension in the direction of movement relative to the series of spaced conductive members greater than the space between the conductive members.

5. Means for controlling the movement of sheet material between first and second paths comprising conveyor means for conducting the sheet material toward the first and second paths, a stationary member positioned in the region between the conveyor means and the first and second paths, continuously energized first electromagentic means positioned in the region of the forward end of the stationary member and spaced above the stationary member to apply an upward force on sheet material leaving the conveyor means and lift the sheet material to above the stationary member, a secondelectromagnetic means located in the region of the forward end of the stationary member and spaced below the stationary member operable when energized to apply a downward force on sheet material leaving the conveyor means and pull the sheet material to below the stationary member, and means for energizing the second electromagnetic means, the second electromagnetic means when energized producing a downward force on sheet material greater than the upward force continuously produced by the first electromagnetic means.

6. Means for controlling movement of sheet material between first and second paths comprising conveyor means for conducting the sheet material toward the first and second paths, the conveyor means and the first path lying in a substantially common plane, a stationary vane member positioned in the region between the conveyor means and the first and second paths, the vane member lying in the common plane and above the second path, continuously energized first electromagnetic means positioned in the region of the forward end of the stationary vane member and spaced above the stationary vane member to apply an upward force on sheet material leaving the conveyor means and lift the sheet material to above the stationary vane member, a second electromagnetic means located in the region of the forward end of the stationary vane member and spaced below the stationary vane member operable when energized to apply a downward force on sheet material leaving the conveyor means and pull the sheet material to below the stationary vane member, and means for energizing the second electromagnetic means, the second electromagnetic means when. energized producing a downward force on sheet material greater than the upward force continuously produced by the first electromagnetic means.

7. In a shear line for continuous strip material including a shear for cutting successive sheet portions of continuous strip material into sheets of predetermined length and deflector means operable to direct sheets along a predetermined path, the combination comprising means for detecting defects in the strip material on its way to the shear and producing signals indicative of such defects, a series of isolated energy storage elements each indicative of a single sheet portion of the continuous strip material, coupling means for successively connecting the output of the detector means to isolated energy storage elements of the series at a frequency corresponding to the frequency at which sheet portions pass the detector means, means for synchronizing the coupling means so that the output of the detector means is connected to a storage element at the time the leading edge of a sheet portion approaches the detecor means whereby signals from the detector means indicative of defects in the sheet portions of the strip material are stored in separate isolated energy storage elements, means for removing signals from the series of isolated energy storage elements at a rate corre sponding to the rate defective portions move relative to the detector means in synchronism with sheets formed from respective sheet portions, and means for operating the deflector means responsively to the removed signals, the removed signals being delayed to operate the deflector means at the proper time to direct defective sheets along the predetermined path.

8. In a shear line for continuous material including a shear for cutting successive sheet portions of continuous material into sheets of predetermined length and deflector means operable to direct sheets along a predetermined path, comprising detector means for detecting a defect in the continuous material and producing a signal indicative of said defect, energy storage means, means for passing said signal indicative of said defect to the energy storage means, means including the energy storage means for producing a signal indicative of a single sheet portion of the continuous material having said defect in response to passing to the energy storage means of said signal indicative of said defect, and means for operating the deflector means responsively to the signal indicative of a single sheet portion of the continuous material having said defect to direct a sheet having said defect along the predetermined path.

9. Apparatus for inspecting and shearing successive sheet portions of continuous material into sheets and classifying the sheets in accordance with a characteristic of the material determined while the material is in continuous form including a shear for forming sheets from sheet portions of the continuous material, guide means for guiding the continuous material to the shear, means for conveying sheets formed from the continuous material away from the shear, and deflecting means located in the path of travel of shets conveyed away from the shear for deflecting sheets along a predetermined path in accordance with a characteristic of the sheets determined when the material is in continuous form, comprising detecting means located along the guide means in advance of the shear for producing an output signal in response to a characteristic of the material in continuous form, means responsive to the output signal of the detecting means for determining the sheet portion of the continuous material including said characteristic, means synchronized with the shear for following movement of said sheet portion along the guide means to the shear, means responsive to the last-named means for producing a control signal indicative of the sheet formed from said sheet portion, and means responsive to the control signal for operating the deflecting means to deflect said sheet along the predetermined path.

10. Apparatus for inspecting and shearing successive sheet portions of continuous material into sheets and classifying the sheets in accordance with a characteristic of the material determined while the material is in continuous form including a shear for forming sheets from sheet portions of the continuous material, guide means for guiding the material in continuous form to the shear, means for conveying sheets formed from the continuous material away from the shear, and deflecting means located in the path of travel of sheets conveyed away from the shear for deflecting sheets along a predetermined path in accordance with a characteristic of the sheets determined when the material is in continuous form, comprising detecting means located along the guide means in advance of the shear for producing an output signal in response to a characteristic of the material in continuous form, means responsive to the output signal of the detecting means for producing a signal indicative of the sheet portion of the continuous material including said characteristic, means for advancing in time a signal indicative of said sheet portion including said characteristic in synchronism with movement of said sheet portion along the guide means from the detecting means to the shear, means responsive to the advanced signal for producing a control signal indicative of the sheet formed from said sheet portion, and means operative responsively to the control signal for operating the deflecting means to direct said sheet along the predetermined path.

No references cited

Claims

1. IN A SHEAR LINE FOR CONTINUOUS STRIP MATERIAL INCLUDING A SHEAR FOR CUTTING SUCCESSIVE SHEET PORTIONS OF CONTINUOUS STRIP MATERIAL INTO SHEETS OF PREDETERMINED LENGTH AND DEFLECTOR MEANS OPERABLE TO DIRECT SHEETS ALONG A PREDETERMINED PATH, THE COMBINATION COMPRISING DETECTOR MEANS FOR DETECTING DEFECTS IN THE STRIP MATERIAL ON ITS WAY TO THE SHEAR AND PRODUCING SIGNALS INDICATIVE OF SUCH DEFECTS, A SERIES OF ISOLATED ENERGY STORAGE MEANS EACH INDICATIVE OF A SINGLE SHEET PORTION OF THE CONTINUOUS STRIP MATERIAL, MEANS FOR SUCCESSIVELY COUPLING THE DETECTOR MEANS TO ISOLATED ENERGY STORAGE MEANS OF THE SERIES IN SYNCHRONISM WITH SUCCESSIVE MOVEMENT OF SHEET PORTIONS