US3568485A

US3568485A - Method and apparatus for straightening and testing workpieces

Info

Publication number: US3568485A
Application number: US751465A
Authority: US
Inventors: Joseph M Mandula Jr
Original assignee: Republic Steel Corp
Current assignee: Republic Steel Corp
Priority date: 1968-08-09
Filing date: 1968-08-09
Publication date: 1971-03-09
Anticipated expiration: 1988-03-09
Also published as: DE1940476A1; GB1283586A; FR2015382A1

Abstract

APPARATUS FOR STRAIGHTENING AND TESTING WORKPIECES INCLUDES A MACHINE FRAME SUPPORTING STRAIGHTENING ROLLERS. THE APPARATUS ALSO INCLUDES A WORKPIECE TESTING ASSEMBLY WHICH IS REMOVABLY SUPPORTED BY THE FRAME. THE TESTING ASSEMBLY INCLUDES A FLAW DETECTING ELEMENT AND A MARKER WHICH MARKS LOCATIONS OF FLAWS DETECTED BY THE SENSING ELEMENT. IN THE DISCLOSED EMBODIMENT A GUIDE ROLL ENGAGES THE WORKPIECE AS IT PASSES FROM THE APPARATUS.

Description

' Mai'ch 9, 1971 J. M. MANDULA, JR 3,568,485

METHOD AND APPARATUS FOR STRAIGHTENING AND TESTING WORKPIECES 4 Sheets-Sheet 1 Filed Aug. 9, 1968 FIG.|

mm am 00 N N A m M H P E S 0 v .0 H

BY ums l-{oWmannFishmli Hakka.

ATTOR NEYS.

March 9, 1971 J. M. MANDULA, JR 3,563,435

METHOD AND APPARATUS FOR STRAIGHTENING AND TESTING WORKPIECES Filed Aug. 9, 1968 v 4 Sheets-Sheet 2 INVENTOR. JQSEPH M. MANDULAJR Ufoiis, HoHmunnIFusMi Hu nVL ATTORNEYS.

March 9, 1971 MANDULA, JR 3,568,485

I METHOD AND APPARATUS FOR STRAIGHTENING AND TESTING WORKPIECES Filed Aug. 9, 1968 4 Sheets-Sheet 5 INVENTOR. JOSEPH M. MANDULAJK BY 11311115, HoHmQnnTHShUL$ Heinklb I ATTOR N EYS.

March 9, 1971 J. M. MANDULA, JR 3,568,485

METHOD AND APPARATUS FOR STRAIGHTENING AND TESTING WORKPIECES Filed Au 9, 1968 4 Sheets-Sheet 4 INVENTOR. JOSEPH M.MANDU'LA,JR

Waits ,Hofl monfirFiShlb$Hdnvz AT TQR N EYS.

3,568,485 METHOD AND APPARATUS FOR STRAEGHTEN- ING AND TESTING WORKPIECES Joseph M. Mandala, Jr., Seven Hills, Ohio, assignor to Republic Steel Corporation, ieveland, Ohio Filed Aug. 9, 1968, Ser. No. 751,465 Int. Cl. B216 3/04 US. Cl. 72-10 22 Claims ABSTRACT OF THE DISCLOSURE Apparatus for straightening and testing workpieces includes a machine frame supporting straightening rollers. The apparatus also includes a workpiece testing assembly which is removably supported by the frame. The testing assembly includes a flaw detecting element and a marker which marks locations of flaws detected by the sensing element. In the disclosed embodiment a guide roll engages the workpiece as it passes from the apparatus.

CROSS REFERENCES TO RELATED PATENTS AND APPLICATIONS US. Pat. No. 3,263,809, entitled Apparatus for Defect Analysis in Classification of Workpieces issued Aug. 2, 1966, to Mandula and Judd.

Copending application Ser. No. 365,130, filed May 5, 1964 entitled Apparatus and Method for Inspecting and Propelling Elongated Workpieces.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to production and inspection of workpieces and more particularly relates to a method and apparatus for straightening and inspecting workpieces.

(2) The prior art Non-destructive defect detection systems used in conjunction with the production of bar stock, seam welded tubing etc. have been constructed. One such inspection system is disclosed in the referenced US Pat. 3,263,809.

The apparatus disclosed in that patent utilizes a sensing head which electrically detects the existence and severity of flaws in the workpiece and a marker for marking the flaws. For proper operation of the disclosed system it is necessary that the flaw detecting head of the apparatus be engaged with a periphery of the workpiece being inspected.

The referenced Pat. No. 3,623,809 and the referenced copending application Ser. No. 365,130, disclose a system for inspecting workpieces and classifying the workpieces into good, salvageable, or scrap. This system provides for automatically taking workpieces from a stock pile, propelling them past the inspection and marking apparatus and classifying them into one of the noted categories. The disclosed system permits complete inspection of the workpiece regardless of irregularities.

An inspection apparatus must be constructed to permit the sensing head to accommodate irregularities in the workpiece as the workpiece and sensing head are moved relatively. While the apparatus of the referenced patent has been highly successful and is far superior to visual inspection there are times when the sensing head and workpiece separate causing flaws to be partly or wholly missed. There are also times when irregularities of a workpiece are of such magnitude that the floating support of the sensing head cannot accommodate the irregularities and damage to the sensing head may result.

With workpieces which are classified by Mill standards as straight it ,is possible for the workpieces to have nited States Pate 3,568,485 Patented Mar. 9, i971 SUMMARY OF THE INVENTION The present invention provides a method and apparatus for detecting defects in rod-like articles regardless of irregularities in their shape wherein the workpiece is directed along a path of travel past a defect detecting location and wherein successive locations on the article are constrained for movement along a line past the detecting location regardless of irregularities in the workpiece tending to be laterally displaced from the line.

In one embodiment of the invention defect detecting and marking apparatus is integral with production machinery so that workpieces being produced can be inspected and suitably marked during the course of production. This minimizes the amount of visual inspection necessary. Additionally, defects which are generally not discoverable by visual inspection are detected and marked in accordance with the invention by apparatus requiring minimal floor space and relatively small capital outlay.

The present invention is illustrated and described in conjunction with the production of bar stock and more particularly in conjunction with a bar straightening machine having rollers which straighten a round bar while advancing and rotating the bar along a path of travel through the machine. The defect detecting apparatus includes a sensing head which is located along the path of travel immediately adjacent the last rollers. A workpiece is engaged by the detecting head just as it emerges from these rollers. This permits the sensing head to be positioned at locations which are relatively stable even if the portion of the bar that has not emerged from the rollers is cambered.

The sensing head is supported on the frame of the straightening machine and is associated with an actuator for moving the sensing head into and out of engagement with a workpiece. A workpiece marking assembly, or marker, is supported adjacent the sensing head. The marker and sensing head are associated through suitable control apparatus. Defects detected by the sensing head cause the control apparatus to actuate the marker to appropriately mark the defect.

Further in accordance with the present invention the sensing head is carried by a supporting assembly which permits removal of the head and marker during setting up of the machine. The supporting assembly also permits adjustment of the position of the sensing head to accommodate different sized stock.

The sensing head is gimbal mounted on a supporting arm and the arm itself is rotatable about the axis spaced from the head. Due to this mounting of the sensing head, it rides on the surface of the workpiece. The straightener of this invention limits the magnitude of irreglarities in the bar so that they are ineffective to disengage the sensing head from the surface of the bar. Whipping of the workpiece relative to the sensing head is minimal due to the close proximity of the rollers to the sensing head. Thus due to the mounting structure for the sensing head the straightening of the bar, and the prevention of whipping, the surface of the bar cannot move relative to the head in a direction transverse to the workpiece path of travel.

In some installations it may be necessary to provide a guide roll spaced along the path of travel of the U workpiece from the sensing head. The guide roll is effective to engage the workpiece and dampen any tendency of the workpiece to whip as the trailing end of the workpieces emerges from the straightening rolls adjacent the sensing head. Furthermore the guide roll prevents bars from damaging the head if a roll-out table adjacent the machine is not properly positioned.

Accordingly a principal object of the present invention is the provision of a new and improved method and apparatus for straightening and testing articles of manufacture wherein defects in a workpiece are sensed and marked during production.

Other objects and advantages of the present invention will become apparent from a consideration of the following detailed description thereof made with reference to the accompanying drawings which form a part of the specification.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of apparatus for straightening and testing workpieces embodying the present invention.

FIG. 10 is a schematic view of electrical and pneumatic circuits forming a part of the apparatus of FIG. 1;

FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1;

FIG. 3 is a view of a defeat detecting assembly forming part of the apparatus of FIG. 1;

FIG. 4 is a view of the assembly of FIG. 3 seen from the plane indicated by the line 44;

FIG. 5 is a view of a defect marking assembly forming part of the apparatus of FIG. 1; and,

FIG. 6 is a view of workpiece detecting elements seen from the plane indicated by the line 66 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates apparatus 10 for straightening and inspecting a workpiece W which moves along a path of travel P illustrated by the arrows in FIG. 1. The WOrkpiece W may be of any suitable form such as pipe, tubing etc., but is illustrated and described as cylindrical bar stock.

The apparatus 10 includes a frame F of heavy construction. The frame F supports drive rolls 11, 12 and a respectively associated idler rolls 13, 14. The roll pairs 11, 13; 12, 14 respectively, are disposed at spaced locations along the work path P. A pressure roll 15 is along the path and between the roll pairs.

The roll pairs 11, 13; and 12, 14, advance the workpiece W through the apparatus 10 and rotate the workpiece about its longitudinal axis while the work ad vances. The straightening roll 15 engages the workpiece W between the roll pairs to straighten the work as it is adavnced. The construction and configuration of the rolls themselves are conventional and accordingly are shown schematically.

When the workpiece W emerges from the rolls 12, 14 it passes through an inspection station S. The workpiece then passes under a guide roll Zea of a guide roll assembly 2d. The assembly 21 is connected at the discharge end of the apparatus. The assembly guides the work W onto a roll-out table 21 which moves the straightened work W away from the apparatus. The rollout table 21 is illustrated as including a plurality of driven rollers two of which 22, 23 are illustrated schomatically in FIG. 1.

It should be appreciated that the rolls 12, 14 guide successive locations on the workpiece W along a substantially straight line adjacent the location at which the workpiece emerges from them regardless of irregularities in the workpiece. More specifically the workpiece is engaged by the rolls and at locations adjacent the rolls the workpiece is constrained against movement laterally from the line of movement even though locations on the workpiece remote from the rolls may tend to move substantial distances laterally of the path of travel.

A defect detecting and marking system is shown schematically in FIG. 1 at the inspection station S. The system 25 detects and marks defects in the workpiece W as it passes through the apparatus. The system 25 includes a defect sensing head H, a marking assembly, or marker, M and control circuitry C governing operation of the system 25, FIG. la.

The defect sensing head H and marker M are each cosntructed for indexing movement relative to the path of travel of the workpiece W. Thus, a flaw detecting element of the sensing head H is brought into close proximity to the surface of the workpiece and is shifted away from the path of travel when a workpiece is not present. Similarly, a marking element of the marker M is moved into and away from its workpiece marking positions.

The assemblies including the head H and the marker M are described in considerable detail presently. These assemblies are pneumatically operated through solenoid controlled air valves V1, V2. Thus when the solenoid valve V1 is energizes the head H is indexed to a position wherein sensing of defects in the workpiece is possible and when a solenoid valve V2 is energized, the marker M is indexed to mark the workpiece.

As shown in FIG. 1a the head H is electrically connected to the circuitry C. The head H provides input signals to the circuitry C in response to the presence of defects in workpieces. The signals from the head H are transmitted to an oscillator O which in turn transmits a strengthened signal to a control unit U. The control unit U includes circuitry for producing an output signal in response to defect signals from the oscillator O. The valve V2 is connected across an output circuit 24 of the control unit and the valve V2 is energized to cause marking of the workpiece when a defect signal is received by the unit U.

The circuitry in the control unit is connected to a suitable power supply through a control box B. The box B includes suitable switches for permitting manual and automatic operation of the system 25 as well as an on/off control switch for the system 25.

The details of construction of the box B can be of any suitable type and accordingly are not described in detail, The box B and oscillator O are disposed on the frame F of the apparatus -16 and the control unit is preferably positioned adjacent the apparatus 10 as illustrated in FIG. 1.

The head H is moved into engagement with the workpiece W only when a portion of the workpiece W is in the station S. Accordingly, the valve V1 is connected in series with switches S1, S2 the contacts of which are linked to paddle-like sensors 26a, 26b disposed along the path of travel of the workpiece, FIG. 6. When the workpiece emerges from the rollers 12, 14 and engages the sensors 26a, 26b the switches S1, S2 are closed to complete an energization circuit for the valve V1 and the sensing head H is brought into engagement with the workpiece.

In a preferred embodiment the box B contains switches (not shown) permitting manual control of the head H and marker M for setup of the apparatus. The manual control switch for the head H is associated with conductors 27a, 27b establishing an energizing circuit for the valve V1 when the switches S1, S2 are open. The control switch for the marker M is connected to the valve V2 through conductors 28a, 28b so that the marker M is indexible in the absence of an output signal from the unit U.

Referring now to FIG. 2, the head H and marker M are supported over the workpiece W by a support structure 30. The support structure 30 includes a body 31 which is fixed to the frame F by suitable fasteners. A spacer 31a of the shape of an inverted square U is fixed to an end of the body 31 which projects from the frame F toward the path of travel P.

A support 33 is clamped to the spacer 31a. The support 33 includes a clamp 34 and a support arm 35 extending parallel to the path P. The sensing head H and marker M are supported near the projecting end of the support arm 35. The spacer 31a is longer than the clamp 34 is wide to permit adjustment of the position of the clamp along the spacer. In the preferred embodiment the spacer is composed of Bakelite or similar material which is slightly resilient and resists wear.

The defect sensing head H includes a sensing coil or element 36 positionable adjacent the top of the workpiece W. The coil 36 is supported by a body 37 so that the coil is positioned adjacent the work W at a location on the path P which is immediately adjacent the location at which the workpiece W emerges from the rolls 12, 14. The coil 36 is supported by a hinged arm assembly 40 extending between the end of the support arm 35 and the element 36.

The valves V1, V2 are connected to the frame F a short distance from the path of travel P. In the preferred embodiment the valves V1, V2 form part of an assembly which includes a manual control valve V3 which is adjustable to provide a desired air pressure to the valves V1, V2. The electrical wiring and air hoses extending between the various elements of the system 25 are preferably flexible to permit removal of the support arm 35, head H and marker M from the body 31. For clarity, only end portions of some of the wiring and air hoses are illustrated in FIG. 2.

The head assembly H including the assembly 40 and element 36 is illustrated in FIGS. 3 and 4. The assembly 40 includes a sleeve bearing disposed about a cylindrical shaft portion 51 of the support arm 35. The bearing 50 is freely rotatable relative to the shaft 51. A pair of

arms

52, 53 connected to the bearing 50 to a gimbal assembly 54. The gimbal assembly 54 carries the body 37 and element 36.

The arm 52 includes a sleeve member 55 attached to the bearing 50 and a member 56 which is telescopically received in the sleeve 55, The member 56 includes a plurality of openings (not shown) spaced longitudinally along its length. The sleeve 55 includes an opening (not shown) which is alignable with a selected opening in the 'member 56. A fastener 57 extends through the aligned openings to fix the sleeve 55 and member 56 together. Thus, the length of the arm 52 can be adjusted to change the position of the element 36 relative to the support arm 35.

The opposite end of the member 56 includes a platelike portion 60 having a pair of depending tabs 6001 on opposite sides of the arm 53. A pivot pin 61 extends through openings in the tabs 60a and arm 53 so that the arm 53 is rotatable relative to the plate 60. A compression spring 62 is disposed between the plate 60 and member 53. The spring 62 normally urges the member 53 in a counterclockwise direction about the pivot pin 61 (as viewed in FIG. 3).

The gimbal assembly 54 includes a U-shaped bracket 65 connected to the arm 53. Each leg of the bracket receives a pivot pin 66. The pivot pins 66 rotatably support a generally open rectangular member 67, so that the member 67 is rotatable about an axis X, FIG. 4. The rectangular member 67 supports pivot pins 70 which are fixed to the sensing element 36 and rotatable with respect to the member 67. Thus the sensing element 36 is rotatable about a Y axis with respect to the rectangular member 67.

The defect sensing element 36 is freely rotatable about the X and Y axes. The arm 53 and gimbal assembly 54 are rotatable about the axis Z of the pivot pin 61. Accordingly, the sensing element 36 is universally movable and can ride on the workpiece W regardless of normal surface irregularities or lateral movements of the workpiece.

The assembly 40 is movable toward and away from the periphery of the workpiece by operation of a sensor actuator in the form of a double acting air cylinder which is connected to a source of compressed air through the valve V1. The actuator 75 includes a piston rod 76 fixed to an car 77 attached to the bearing 50. When the valve V1 is energized compressed air is introduced into the sensor actuator and the piston 75A is moved to the left, as viewed in FIG. 3. The ear 77 and the sensing head assembly H are rotated counterclockwise as seen in FIG. 3 so that the element 36 is moved into engagement with the workpiece W.

A stop screw 80 carried on the ear 77 engages a stop surface '81 on the support arm 35 to limit movement of the sensing element 36 toward the workpiece. The stop screw 80 is adjusted so that the force urging the assembly 40 and the element 36 into engagement with the workpiece W is sufiicient to produce light compression of the spring 62. With the spring lightly compressed the body 37 is maintained in engagement with the workpiece W even if the workpiece should include a bend which would move the surface of the workpiece downwardly from the element 36.

When the valve V1 is deenergized compressed air is directed to the actuator 75 to move the piston 75A to the right (FIG. 3). The sensing element 36 is thus shifted away from the workpiece. The air lines to the actuator 75 include

adjustable throttling valves

82, 83 which control the rate of movement of the head H toward and away from the'workpiece.

The sensing head assembly H is adjustable to cooperate with workpieces having various diameters. As noted previously the clamp 34 can be shifted along the spacer 31a. Additionally by loosening the screw 57 and telescoping the member 56 into or out of the sleeve 55 the extent of the support arm 52 can be varied. The stop screw 80 is also adjustable relative to the ear 77 to accommodate differences in the diameter of workpieces.

The marking assembly M is illustrated in FIG. 5, and includes a motor 84. A clamp ring 85 is carried by the motor 84. The ring 85 includes trunnions 86 extending outwardly at diametrically opposed locations. The trunnions 86 engage supports 87 which are fixed to the support arm 35. The trunnions, ring, and supports 87 are constructed so that the motor 84 is rotatable about the axis of the trunnions 86.

The motor has an output shaft 90 having a cutter 92 fixed to its end. The upper halves of the shaft and

cutter

90, 92 are shielded from view in FIG. 5 by a semi-circular housing extension 91. The motor 84 is continuously operated during operation of the system 25 and when the motor is rotated counterclockwise as seen in FIG. 5 about the trunnions 86 the cutter 92 engages and marks the workpiece.

The motor is rotated about the trunnions by a motor actuator 93. The motor actuator 93 is connected to a motor arm 94 which extends from the support arm 35 generally parallel to the motor shaft 90 The motor arm 94 is connected to the support arm 35 by a pivot 95. The motor arm 94 maintains the motor actuator 93 in a position for engagement with the housing extension 91.

A spring assembly 96 extends between the housing extension 91 and the motor arm 94 to provide a biasing force urging the housing extension toward the motor actuator 93. The spring assembly includes a helical compression spring 100 and connecting rod 101. The connecting rod 101 extends from a clevice 102 on the housing extension 91 and through an opening in the motor arm 94. Nut fasteners 103 at the end of the rod 101 maintain the spring 100 in compression against the arm 94 so that the motor 84 and housing extension 91 are biased upwardly to their FIG. 5 positions.

When the valve V2 is energized, the motor actuator 93 7 is supplied with compressed air and piston 93a of the actuator moves the cutter 92, motor, and housing, about the trunnions 86. The cutter 92 engages the workpiece W and marks the surface.

In the preferred embodiment the housing extension 91 is provided with a mass of shock absorbing material 91a shown in broken lines in FIG. 5. The material 91a engages the piston 93a so that undesirable shock loadings on the cutter are avoided. The acutator 93 is constructed so that as soon as the valve V2 is deenergized the spring assembly 96 returns the motor, cutter, and housing to the FIG. position.

The marking assembly M is adjustable to accommodate workpieces of differing diameters. The assembly M includes a linkage 110 for changing the angularity of the support 94 with respect to the support arm 35. The linkage 110 includes an adjusting screw 111 which is supported in a pillow block 112 connected to the support arm 35. A threaded sleeve 113 surrounds the screw 111. A connecting linkage 114 is fixed to the motor arm 94 at one end and to the sleeve 113 at its other end by a suitable bearing 116 of the rod-end type. A knob 117 is connected to the screw 111. As the knob 117 is manually rotated the screw 111 moves the sleeve 113 changing the distance between the pillow block 112 and the bearing 116. Thus, the motor arm 94 is adjustably rotated about the pivot 95. In order to accommodate the adjusting movement the opening in the motor arm 95 which receives the rod 101 extends longitudinally of the motor arm 94.

OPERATION Operation of the apparatus for straightening and testing articles is as follows:

The straightening rolls 1115 are appropriately adjusted to advance and simultaneously straighten a workpiece of given diametrical size. Preferably, during the setup and initial few passes the clamp 34 is loosened and the support arm 35 including the head H and marker M are moved away from the intended path of travel P. This is done because the path of travel of the workpiece is not predictable and damage to the system might otherwise occur.

The assembly H and the marking assembly M are then positioned on the frame F and adjusted relative to the path of travel. The circuitry C is also adjusted if neces sary, to synchronize operation of the marker M with the sensing head H.

The workpiece is introduced into the throat of the straightening rolls and is driven through the machine by the rolls. When the leading end of the workpiece emerges from the rolls 12, 14 the workpiece successively engages the sensors 26a, 26b of the switches S1, S2 to close the switches. Activation of both of the switches S1, S2 energizes the valve V1 causing compressed air to be delivered to the sensor actuator 74. The sensing head is then indexed into engagement with the periphery of the workpiece.

In the preferred construction each sensor 26a, 26b carries a cam 121 which rotates with it. Roller followers 122 are engaged with each cam and are associated with the switches S1, S2 respectively. The sensors, cams and followers are supported by switch housings mounted adjacent the path of travel P. When the sensors are in their broken line positions, FIG. 6, the cams and followers are positioned so that the switches S1, S2 are open. The workpiece engages the sensors and moves them to their solid line positions to effect closing of the switches 51, S2 by the cams and followers. The switch housings .123 are preferably connected to a structural supporting member F1 which is integral with the frame F, FIGS. 2 and 6.

The ends of the bars often have burrs or other irregularities which can damage the head H. In the illustrated form of the invention the sensors 26a, 26b are located so that the leading end of the bar is just past the head H when the head is indexed to a position for detecting de fects. Similarly, the head H is indexed away from a bar just before the trailing end passes the head. Thus, short sections at the ends of bars are not inspected in order to protect the head H against damage from the ends of the bars. Since defects immediately adjacent ends of bars are generally not of great importance, the system 25 is constructed so that the possibility of damage to the system is minimized yet the bars are substantially inspected.

As previously noted the apparatus 10 rotates the workpiece while advancing the workpiece along the path of travel P. Thus, the element 36 scans a helical path along the workpiece. In the event a defect is detected by the element 36, a signal is provided to the circuitry C which in turn energizes the solenoid valve V2 after an appropriate interval. Because of the motion of the workpiece and spacing between the head H and the marker M the circuitry C includes elements for delaying energization of the valve V2 until the sensed defect is adjacent the marker.

Energization of the valve V2 introduces compressed air to the actuator 93 and the cutter 92 is moved into engagement with the workpiece to mark the defect. When an output signal from the unit U is no longer present, the valve V2 is deenergized and the cutter is moved away from the workpiece W by the spring assembly 96.

The leading end of the workpiece proceeds from the apparatus 10 toward the roll-out table 21 and engages the guide roll 20a as it is advanced from the apparatus 10. The guide roll 20a is rotatably supported in a frame-like bracket 125 connected to the frame F of the apparatus FIG. 2. The axis of rotation of the guide roll 20a lies in a horizontal plane and the bracket 125 is constructed to permit vertical adjustment of this roll axis. Additionally the roll 20a is movable horizontally along its axis of rotation to accommodate any irregular motion of bars.

Oftentimes when a roll-out table is not properly aligned with the apparatus 10 the leading end of the bar may be elevated above the table. When the trailing end of the bar is released from the rollers in the apparatus the leading end of the bar tends to fall to the table causing the trailing end of the bar to whip upwardly. The guide roll 20a inhibits this whipping action thereby preventing a trailing end of a bar from damaging the head H and marker M in such circumstances. Additionally the roll 20a stabilizes the bar against whipping movement as the bar advances.

Although 'a preferred embodiment of the invention has been described with a certain degree of particularity. it is understood that the present disclosure of these preferred forms have been made only by way of example and that numerous changes in details of construction and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim:

1. Apparatus for detecting flaws in an elongate workpiece comprising:

(a) a stationary frame structure;

(b) a plurality of rotatable members rigidly supported by said frame structure and disposed along a path of travel of a workpiece;

(c) said members engageable with a workpiece moving along said path to engage and direct successive locations on said workpiece along a helical line and restraining said locations against lateral movement relative to said frame;

(d) defect detecting means including a defect sensing element disposed along said line immediately adjacent said members and proximate said locations; and,

(e) defects in said workpiece being detected by said sensing element at a location where said workpiece is restrained from moving toward and away from said element.

2. Apparatus as defined in claim 1 further including support structure for said element, said support structure including a first member movable toward and away from said line and an actuator for moving said member.

3. Apparatus as defined in claim 2 wherein said support structure further includes a second member rotatably supported by said first member and a pivot construction connecting said element to said second member so that said element is movable to accommodate irregularities in said workpiece.

4. Apparatus as defined in claim 3 wherein said pivot construction is defined at least in part by a gimbal assembly.

5. Apparatus as defined in claim 3 and further including biasing means urging said element toward a defect sensing position with respect to the path of travel.

6. Apparatus as defined in claim 1 and further including defect marking means disposed along said path of travel, said marking means elfective to mark the locations of defects detected by said detecting means.

7. Apparatus as defined in claim 1 wherein said detecting means is operative to provide a signal in response to the presence of a defect in a workpiece and further including signal processing means and defect marking means, said signal processing means operatively associated with said marking means and said detecting means and effective to render said marking means effective in response to a signal from said detecting means.

8. Apparatus as defined in claim 1 wherein said defect detecting means is indexible from a first position remote from said path of travel to a second defect detecting position adjacent said path, and further including an actuator for moving said detecting means between said positions.

9. Apparatus as defined in claim 8 and further including control apparatus for effecting operation of said actuator to index said detecting means from said first to said second positions in response to the presence of a workpiece at a predetermined location on said path.

10. Apparatus as defined in claim 9 wherein said control apparatus includes a workpiece detecting member controlling operation of actuating means in response to position of a workpiece on said path.

11. Apparatus as defined in claim 1 including a workpiece guide connected to said frame at a location spaced from said members, said guide engaging the workpiece at said location and maintaining said workpiece generally on said path after it has passed said members.

12. A bar testing apparatus comprising:

(a) a bar straightener having a frame;

(b) a plurality of straightener rolls supported by said frame and disposed along a path of travel of bars;

() said rolls engageable with bars moving along said path to rotate and straighten a bar while advancing the bar;

(d) at least one of said rolls engaging a bar and constraining locations on the bar immediately adjacent said one roll against lateral movement away from said path;

(e) defect detecting means supported on said frame including a defect sensing element supported at a location near said path of travel and immediately adjacent a location of engagement between said at least one roll and a bar; and,

(f) support structure for said element including an actuator for indexing said element from a first position spaced from said path to a second defect sensing position adjacent said path of travel.

13. Apparatus as defined in claim 12 and further including bar position sensing apparatus controlling operation of said actuator, said actuator indexing said element to said second position in response to the presence of a bar at a predetermined location on said path.

14. Apparatus as defined in claim 13 wherein said bar position sensing apparatus effects operation of said actuator to index said sensing element to said first position when a trailing end of the bar reaches a predetermined position on said path.

15. Apparatus as defined in claim 12 and further including a bar engaging element spaced from said at least one roll in the direction of travel of bars, said bar engaging member etfective to stabilize movement of a trailing end of said bar as said bar is moved from said apparatus.

16. Apparatus as defined in claim 12 and further including defect marking means adjacent said defect detecting means and control apparatus effecting operation of said marking means in response to detection of defects by said sensing means.

17. Apparatus as defined in claim 16 wherein said marking means includes actuating structure and workpiece marking apparatus, said actuating structure operating said marking apparatus to mark the workpiece at locations at which defects are detected.

18. A method of inspecting a curved bar including the steps of:

(a) moving a bar along a path of travel;

(b) rigidly supporting said bar at at least two fixed locations along said path while moving said bar;

(c) restraining said bar against lateral movement at at least one of said locations; and

(d) inspecting said bar for defects adjacent said one of said locations while moving said bar.

19. A method of inspecting a bar as defined in claim 18 wherein said inspecting step includes the steps of sensing defects in a bar at said one location and marking the locations of sensed defects.

20. A method of inspecting a bar as defined in claim 18 and further including the step of sensing the presence of a bar at said one location, and indexing an inspecting element toward said path.

21. A method as defined in claim 20 and further including the step of indexing said inspecting element away from said path when a bar advances past said one location.

22. A method as defined in claim 18 wherein said supporting step includes straightening the bar as it moves along said path and said inspecting step is performed upon straightened portions of the bar.

References Cited UNITED STATES PATENTS 236,245 1/ 1881 Nuttall 72-99 3,263,809 8/1966 Mandnla, Jr. et al. 20973 3,349,611 10/1967 Benjamin et a1. 33-147 3,391,463 7/1968 Ambers et a1. 33l49 MILTON S. MEHR, Primary Examiner US. Cl. X.R.