US3886793A

US3886793A - Projectile body testing machine

Info

Publication number: US3886793A
Application number: US432021A
Authority: US
Inventors: Henry E Cramer; James M Gerkin; Dale L Groh; Gale A Groh
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1974-01-09
Filing date: 1974-01-09
Publication date: 1975-06-03
Anticipated expiration: 1992-06-03

Abstract

A fully automatic machine for non-destructive testing of projectile bodies. The machine includes an eddy-current station for inspection for cracks or holes in the nose threads of a projectile body and an ultrasonic station for inspection for cracks or holes in the body of the projectile from the rotating band to the bottom edge of the nose threads. A material handling system is provided to transport the projectile bodies to and from the inspection station and a memory device is provided to record a projectile body that fails a test. A marking device is connected with the memory system to mark each projectile body that passes both tests.

Description

United States Patent Cramer et al.

PROJECTILE BODY TESTING MACHINE Inventors: Henry E. Cramer, Loogootee;

James M. Gerkin; Dale L. Groh, both of Bedford; Gale A. Groh, Mitchell, all of Ind.

The United States of America as represented by the Secretary of the Navy, Washington, DC.

Filed: Jan. 9, 1974 Appl. No.: 432,021

Assignee:

U.S. Cl. 73/167; 73/67.5 R Int. Cl. G0lm 3/16 Field of Search 73/67.5 R, 67.6, 67.7,

References Cited UNITED STATES PATENTS l/l971 Skubiak et al 73/67.8 S

3,575,042 4/1971 Lovelace 73/67.8 S

Primary ExaminerJerry W. Myracle Attorney, Agent, or FirmR. S. Sciascia; Paul S. Collignon [57] ABSTRACT A fully automatic machine for non-destructive testing of projectile bodies. The machine includes an eddycurrent station for inspection for cracks or holes in the nose threads of a projectile body and an ultrasonic station for inspection for cracks or holes in the body of the projectile from the rotating band to the bottom edge of the nose threads. A material handling system is provided to transport the projectile bodies to and from the inspection station and a memory device is provided to record a projectile body that fails a test. A marking device is connected with the memory system to mark each projectile body that passes both tests.

7 Claims, 6 Drawing Figures CONVEYOR .EDDY-CURRENT ULTRASONIC I MARKING CONVEYOR LOAD TEST TEST UNLOAD l2 [3 l l 74 16 17 MEMORY PATENTEDJUH 3 I975 SHEET PATEIHEBJUH 3 1975 SHEET Fig.6

PROJECTILE BODY TESTING MACHINE BACKGROUND OF THE INVENTION The present invention relates to a testing machine for projectile bodies. A large projectile, such as a inch 38 caliber shell or a 5 inch 54 caliber shell, will occasionally have an internal crack or hole which, if undetected, could create a hazardous condition to personnel.

Projectile bodies are normally forged or drawn from a cubical billet which. if not sound, could cause a defective projectile body. Also the necking down operation of the nose section sometimes causes cracks in the high carbon steel. These projectile bodies are loaded with dry power which is pressed under very high pressure which causes a crack to open and power to flow into the crack. Upon removal of the pressing force, the crack has a tendency to close and can cause a detonation thereby creating extreme hazard to an operator of the press. Accordingly, it is very important that projectile bodies having internal cracks be detected prior to filling with powder.

SUMMARY OF THE INVENTION The present invention relates to a fully automatic testing machine for non-destructive testing of projectile bodies. Projectile bodies are loaded at one end of the machine and travel through two inspection stations and are unloaded at the opposite end. The projectile bodies that pass both inspection stations are marked with a colored dye by a jet shot system. One inspection station is an eddy-current station wherein the projectile body is maintained stationary while an eddy-current inspection probe enters into the nose of the projectile to test the nose threads. The second inspection station is an ultrasonic test station wherein the projectile is rotated under water while an inspection probe travels the length of the projectile body.

It is therefore a general object of the present invention to provide a fully automatic non-destructive testing of projectile bodies providing an eddy-current test of nose threads and an ultrasonic test of the projectile body.

Other objects, advantages and novel features of the invention will become apparent from the following de tailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow-diagram showing the basic operations of a preferred embodiment of the present invention;

FIG. 2 is a perspective view of a preferred embodiment of the present invention;

FIG. 3 is a partial side view showing the two inspection stations of the preferred embodiment;

FIG. 4 is an end view showing a projectile body at the eddy-current inspection station;

FIG. 5 is a view similar to FIG. 4, only showing an eddy-current probe in position to enter the nose section of a projectile body; and

FIG. 6 is an end view showing a projectile at the ultrasonic test station.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 1 and 2 of the drawings, projectile bodies 11 are loaded onto a conveyor at station 12 and then travel to station 13 for an eddy-current test. When the first projectile body reaches the eddycurrent test station, the conveyor stops and the projectile is raised from its conveyor cradle and positioned to receive an eddy-current probe which moves into the nose thread section. After the probe is withdrawn from the nose thread section of the projectile body, the projectile body is lowered back into its conveyor cradle and the conveyor then moves the projectile body to the ultrasonic test station 14. During the ultrasonic test, the projectile body is immersed in water and rotated while the test probe moves longitudinally with respect to the projectile body. During this ultrasonic test, another projectile body can be tested at eddy-current test station 13. In the event that a projectile body does not pass either the eddy-current test or the ultrasonic test, this failure will be noted by the memory 15 and when the failed projectile body reaches marking station 16, the marking unit will not be energized and a dye mark will not be placed on the projectile body. After passing through marking station 16, the projectile bodies are unloaded from the conveyor at station 17 and the faulty projectile bodies can be removed from those projectile bodies that passed both tests and received a dye mark.

Referring particularly to FIG. 2 of the drawing, a projectile body 11 is shown in a loading position immediately prior to being moved into a cradle on conveyor 18. The projectile body 11 is supported on inclined support rails 19 and held-back by gate 21. When an empty cradle arrives to receive a projectile body 11, gate 21 is pivoted to allow a projectile body to rolldown support rails 19. When there is another projectile body 11 adjacent or behind the one being loaded, gate 21 prevents the next or adjacent projectile body from loading so that only a single projectile body can roll down support rails 19 into a cradle 18.

When a projectile body 11 reaches eddy-current station 13, the projectile body 11 trips a switch which initiates an electrical control system to perform an eddycurrent test. As best shown in FIGS. 2, 3, and 4 of the drawings, when projectile body 11 reaches station 13, conveyor 18 stops and support frame 22 is raised by air cylinder 30. A pair of V-shaped blocks 23 mounted on frame 22 raises projectile body 11 above cradle 24 so that body 11 is at an exact height to receive eddycurrent probe 25. Using an eddy-current test technique, a beryllium copper probe with embedded coils enters the nose of projectile body 11 and, if a crack or other defect is present, an unbalanced condition will exist and electronic instrumentation 26 will display the abnormality on cathode ray tube 27. The eddy-current probe and associated electronic instrumentation can be purchased commercially and one source of supply is Automation Industries, Inc., Danbury. Conn. 06810. The probe and associated instrumentation are calibrated by using a sound empty projectile body into which a notch of predetermined size has been machined in the nose threads. As probe 25 is rotated during advancement into the nose thread area of projectile body 11, probe 25 scans in a helical pattern. As best shown in FIG. 5 of the drawings, probe 25 and its associated equipment 28 are mounted on table 29 which, in turn, is slidably mounted on

rails

31 and 32. A ball screw 33 is provided and connects with threads in table 29 so that rotation of ball screw 33 by motor 34 through an appropriate gear reducer will advance table 29 so that probe 25 can enter into projectile body 11.

A reversal of motor 34 will retract table 29 thereby withdrawing probe 25.

Upon completion of the eddy-current test at station 13, conveyor 18 is again started and projectile body 11 is moved to station 14 where projectile body I I is given an ultrasonic test while immersed in water. Projectile body 11 is again raised above cradle 14 and is held by two pair of rollers 35 which are rotated by a chain drive 36, so that projectile body 11 is rotated during the ultrasonic test. In the ultrasonic test, projectile body 11 is scanned circumferentially so as to cover the entire wall thickness around the circumference between the projectile nose guard and the rotating band seat. Projectile body 11 is rotated while submerged in water which acts to couple the ultrasonic energy between a transducer 37 and projectile body 11. Using a pulseecho ultrasonic test technique, a pulsed sound wave is transmitted from transducer 37 by water coupling to projectile body 11. The resulting shear wave in the metal is refracted within the steel body. Transducer 37 acts in the receive mode during the pulse-off time, as established by the pulse rate of the ultrasonic instrument. If a crack or other defect is present, a reflection is transmitted back through the metal and to the transducer 37. The echo signal appears on cathode ray tube 38 in ultrasonic instrument cabinet 39 and the height of the signal is representative of the approximate size of the crack. The ultrasonic instrument is calibrated by using a sound empty projectile body into which notches of predetermined size have been machined.

Referring particularly to FIG. 6 of the drawings, transducer 37 is moved across the prescribed length of projectile body 11 by a drive screw 41 which is rotated by motor 42 through gear box 43. The height of transducer 37 is controlled by guide bar 44 which is contoured to the configuration of projectile body 11 so that transducer 37 tracks or follows closely to projectile body 11. Chain drive 36, which rotates the four rollers 35 that support and rotate projectile body 11, is driven by motor 45 and gear box 46 through belt 47. Support frame 48 for rollers 35 is attached to frame 49 which is raised and lowered by air cylinder 51. Upon raising frame 49, rollers 35 lift projectile body 11 from its cradle 24 and, upon lowering of frame 49, projectile body 11 is returned to cradle 24. Transducer 37 and its associated electronic gear in cabinet 39 can be purchased commercially, and one source of supply is Automation Industries, Inc., Danbury, Conn. 06810.

As best shown in'FIGS. 2 and 3 of the drawings, water is contained in tank 52 and a water recirculation system is employed to provide a controlled environment for the ultrasonic inspection. A tank 53 contains make-up water and a recirculating pump 54 is employed to circulate water through a filtering system, into make-up tank 53 and back to tank 52. Although not shown, a float can be provided to maintain the proper level of water in tank 52 and a heater can be provided to maintain the water at a desired temperature. After a projectile body 11 leaves tank 52 it is dried by compressed air which is directed by a nozzle into the interior of projectile body 11.

A memory device is provided to retain information that a particular projectile body did not pass either or both the eddy-current test and the ultrasonic test. Memory devices are commercially available and one source of supply is Ebbert Engineering Co., Troy, Michigan, which makes a ball memory system. In this ball memory device, three drums are provided, each having a plurality of holes for receiving steel balls. The first drum receives a ball for each projecting body 11 moving through the machinev The second drum receives a ball for a particular projectile body 11 that fails the eddy-current test and the third drum receives a ball for a particular projectile body 11 that fails the ultra- SOTIIC {681.

As best shown in FIGS. 2 and 3 of the drawings, a marking device 16 is provided to mark each projectile body 11 that passes both the eddy-current test and the ultrasonic test. A jet shot marker 55 receives dye from reservoir 56 and jet shot marker 55 is programmed and pneumatically operated to mark each projectile body 11 that passes. Memory 16, however sends a signal to prevent marking those projectile bodies 11 that have failed either the eddy-current test or the ultrasonic test. After passing the marking station, projectile bodies 11 are carried onto two parallel rails 58 that separate projectile bodies 11 from their cradles.

As various switches, relays, valves and the like are required for automatic operation of the test machine described herein, a control console 57. is provided for conveniently mounting in one place, all the switches and knobs required to operate the test machine.

OPERATION In operation, projectile bodies 11 are loaded onto the machine at station 12 and gate 21 assures that one projectile body is loaded in a cradle 24. Conveyor 18 then moves cradles 24 until a cradle containing a projectile body 11 reaches the eddy-current test station whereupon conveyor 18 stops. Support frame 22 is raised by air cylinder 30 and V-blocks 23 raise projectile body 11 from its cradle so that the projectile body 11 is aligned to receive eddy-current probe 25. Probe 25 is rotated as it advances into the nose section of projectile body 11 so that it scans in a helical pattern. If a crack or other defect is present in the nose section of the projectile body 11, an unbalanced condition will exist in the coils in the eddy-current probe and the electronic instrumentation associated with the probe will display the abnormality on cathode ray tube 27. Also a failure of a projectile body 11 to pass the eddy-current test will be noted by memory 15 so that the defective projectile body 11 will not be marked when it reaches marking station 16. After eddy-current probe 25 is retracted from projectile body 11, support frame 22 is lowered and projectile body 11 is returned to cradle 24.

Conveyor 18 is started and projectile body 11 moves to the ultrasonic test station, where the conveyor is again stopped. Projectile body 11 is again raised from cradle 24 and is supported by four rollers 35 which are rotated so that projectile body 11 is rotated during the test. Transducer 37 moves longitudinally, near the periphery of projectile body 11, and thus a helical scan pattern is made. The test is conducted under water and a pulse sound wave is transmitted from the transducer by water coupling to the projectile body. The resulting shear wave in the metal is refracted within the steel body of the projectile, and the transducer acts in the receive mode during the pulse-off time. If a crack or other defect is present in the projectile body, a reflection is transmitted back through the metal and to the transducer 37. The echo signal height on the ultrasonic instrument cathode ray tube 38 is representative of the size of a crack and if the crack exceeds a certain size,

the projectile body is considered a reject and this is noted by memory so that the defective projectile body will not be marked when it reaches marking station 16.

AS projectile bodies 11 reaches the marking station 16, sound bodies are given a shot of dye by jet short marker 55 and those projectile bodies that failed either the eddy-current test or the ultrasonic test are not marked. When the projectile bodies 11 reach unloading station 17, the projectile bodies 11 move onto parallel rails 58 and cradles 24 travel in a continuous pattern.

lt can thus be seen that the present invention provides a fully automatic machine for non-destructive testing of projectile bodies. Obviously many modifications and variations of the present invention are possi ble in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

We claim:

1. A machine for non-destructive testing of projectile bodies comprising,

a plurality of cradles each adaptable for holding one projectile body to be tested,

conveyor means for moving said plurality of cradles,

first means for raising a projectile body above its cradle for an eddy-current inspection test,

an eddy-current probe for applying an eddy-current test to said projectile bodies,

means for moving said eddy-current probe into a cavity in said raised projectile while said probe is rotating whereby said probe is moved in a helical pattern into and out of said cavity,

second means for raising a projectile body above its cradle and rotating said projectile body for an ultrasonic test,

an ultrasonic transducer for applying an ultrasonic test to a projectile body raised by said second means, means for moving said transducer along the longitudinal axis of a projectile body raised by said second means, memory means for indicating projectile bodies that are determined to be defective by said eddycurrent inspection test and said ultrasonic test, and

means for marking projectile bodies that have been tested and determined to be sound.

2. A machine for non-destructive testing of projectile bodies as set forth in claim 1 having gate means for loading one projectile body into each cradle.

3. A machine for non-destructive testing of projectile bodies as set forth in claim 1 wherein said first means for raising a projectile body above its cradle includes a hydraulically operated frame having a pair of V blocks thereon adaptable for holding a projectile body.

4. A machine for non-destructive testing of projectile bodies as set forth in claim I having a water tank with water therein with said second means for raising a projectile body being immersed in 'water which acts to couple ultrasonic energy between said transducer and a projectile body raised by said second means.

5. A machine for non-destructive testing of projectile bodies as set forth in claim 1 wherein said means for moving said transducer includes means for causing said transducer to follow the contour of a projectile body being tested.

6. A machine for non-destructive testing of projectile bodies as set forth in claim 1 wherein said means for marking projectile bodies includes a jet shot marker programmed to mark with dye each projectile body and connected with said memory means so as to be deactivated for projectile bodies that did not pass either the eddy-current test or the ultrasonic test.

7. A machine for non-destructive testing of projectile bodies as set forth in claim 1 having means for unloading projectile bodies from said cradles.

Claims

1. A machine for non-destructive testing of projectile bodies comprising, a plurality of cradles each adaptable for holding one projectile body to be tested, conveyor means for moving said plurality of cradles, first means for raising a projectile body above its cradle for an eddy-current inspection test, an eddy-current probe for applying an eddy-current test to said projectile bodies, means for moving said eddy-current probe into a cavity in said raised projectile while said probe is rotating whereby said probe is moved in a helical pattern into and out of said cavity, second means for raising a projectile body above its cradle and rotating said projectile body for an ultrasonic test, an ultrasonic transducer for applying an ultrasonic test to a projectile body raised by said second means, means for moving said transducer along the longitudinal axis of a projectile body raised by said second means, memory means for indicating projectile bodies that are determined to be defective by said eddy-current inspection test and said ultrasonic test, and means for marking projectile bodies that have been tested and determined to be sound.

3. A machine for non-destructive testing of projectile bodies as set forth in claim 1 wherein said first means for raising a projectile body above its cradle includes a hydraulically operated frame having a pair of V-blocks thereon adaptable for holding a projectile body.

4. A machine for non-destructive testing of projectile bodies as set forth in claim 1 having a water tank with water therein with said second means for raising a projectile body being immersed in water which acts to couple ultrasonic energy between said transducer and a projectile body raised by said second means.