US3119019A - Synchronous shutter for x-ray inspecting apparatus - Google Patents

Description

Jan. 21, 1964 E. B. HENRY, JR., ETAL 3,119,019

SYNCHRONOUS SHUTTER FOR X-RAY INSPECTING APPARATUS Filed Feb. 27, 1961 3 Sheets-Sheet l 650 65 J. K/RCHNER B, MflW Attorney Jan. 21, 1964 E. B. HENRY, JR., ETAL 3,119,019

SYNCHRONOUS'SHUTTER FOR X-RAY INSPECTING APPARATUS Filed Feb. 27, 1961 3 Sheets-Sheet 2 L LLB, M,

//v VEN TORS EDWIN a. HENRY Jn, GEORGE .1. K/RCHNER A/lorney Jan. 21, 1964 E. B. HENRY, JR., ETAL 3,119,019

SYNCHRONOUS SHUTTER FOR X-RAY INSPECTING APPARATUS Filed Feb. 27, 1961 3 Sheets-Sheet 5 //V VEN TORS DWI/V B. HEN/P) Jr.

Aflornay United States Patent Ofice 3,119,019 SYNCHRUNOUE SHUTTER FQR X-RAY INSPECTING APPARATUS Edwin B. Henry, .Ira, Mount Lebanon Township, Alle= gheny County, and George J. Kirchner, Whitehall Bore,

Pa, assignors to United States Steel Corporation, a

corporation of New Jersey Filed Feb. 27, 1961, Ser. No. 91,873 Claims. (Cl. 250-105) This invention relates to a shutter for a radiation apparatus.

Although our invention is not thus limited, our shutter is particularly useful as applied to an X-ray fluoroscopy pipe-inspecting apparatus. It is known to employ such apparatus for inspecting welds in large diameter electrically welded steel pipe. The apparatus includes a relatively long stationary horizontal boom and a conventional X-ray head mounted on the end of the boom. A cooperating movable carriage supports the pipe and carries it over the boom with the X-ray head focused on the weld. An inspector watches a fluoroscope situated outside the pipe and observes any impenfections which the X-rays reveal in the weld. For a more complete explanation of the construction and operation of this type of apparatus, reference may be made to a printed publication Pipe Line Industry, August 1959 issue.

One problem encountered in using such apparatus is that the end portions of a weld are not readily inspected. As the end of a continuously moving pipe passes the X-ray head, it exposes a portion of the fluoroscope directly to the X-ray head. If the head is energized at this time, intense radiation produces a brilliant glow on the fluoroscope so that the inspector cannot see any imperfections. Consequently the usual practice is to energize the X-ray head only after the pipe fully covers it and to cut off the X-rays just before the last quarter inch of pipe reaches it. Consequently the end portions of the weld can be fully inspected only if the carriage is stopped. conventionally the end portions are handwelded and more likely to contain imperfections than the remainder, which is machine-welded. Hence the inspection is ineffective for the most critical part of the Weld. Nevertheless it is apparent our invention may be used elsewhere for overcoming analogous problems.

An object of our invention is to provide a shutter which automatically moves in synchronism with relative movement of an article to cover a portion of a ray-directing means left exposed as the ends of an article pass thereover.

A further object is to provide, in combination with an X-ray pipe inspecting apparatus, an automatically operated shutter which enables the apparatus to be used for inspecting substantially the entire weld, including the end portions, while the pipe continues in motion.

A more specific object is to provide, in combination with an X-ray pipe inspecting apparatus, a shutter adapted to cover the X-ray head and a drive for automatically moving the shutter in synchrouism with the pipe, whereby the shutter prevents direct exposure of the fluoroscope to the head as either end of a pipe passes.

In accomplishing these and other objects of the invention, we have provided improved details of structure, a preferred form of which is shown in the accompanying drawings, in which:

FIGURE -1 is an end elevational view, with parts broken away, of an X-ray pipe-inspecting apparatus equipped with our shutter and a pipe positioned thereover;

FIGURE 2 is an end elevational view partly in section showing the X-ray head and shutter on a larger scale;

3 ,lls,tli9 Patented Jan. 21, 1964 FIGURE 3 is a side elevational view on line III-III of FIGURE 2; and

FIGURE 4 is a schematic wiring diagram.

FIGURES 1, 2 and 3 show an X-ray pipe-inspecting apparatus which includes a tubular horizontal boom 10 fixed at one end to a suitable support, not shown, a shelf 12 fixed to the free end of the boom for angular adjust ment about the boom axis, a table 13 mounted on the shelf for sliding adjustment transversely of the boom axis, and an adjusting screw 14- journaled to the shelf and threadedly engaged with the table. A conventional X- ray head 15 is fixed to table 13, as with clamps 16, and has an opening 17 through which it emits rays. An electric cable 18 extends through boom 10 to conduct current to electrically operated mechanism mounted on the boom, such as the X-ray head. A cooperating carriage 26) carries a pipe P over the boom and X-ray head. The carriage runs along rails 21 and is propelled through a motor-driven pinion 22 which meshes with a gear rack 23 intermediate the rails. The carriage includes a cradle 24 on which pipe P actually rests. The pipe has a longitudinal Weld W, and of course is positioned for X-rays emitted through opening 17 to be directed through this weld. An inspector observes the weld through a conventional fluoroscope unit 25 outside the pipe opposite the X-ray head. The structure thus far described is known and not of our invention; hence no more detailed description is deemed necessary.

In accordance with our invention, a bracket 28 is fixed to the edge of table 13 and extends under the X-ray head 15 (FIGURE 3). A shutter 29' is pivoted to the bracket on an axis which intersects the transverse center line of opening 17. The shutter includes a hub 30 journaled to a stub shaft 31 fixed to the lower edge of the bracket, radial arms 32 fixed to the hub, an arcuate frame 33 fixed to the ends of these arms, and spaced arcuate lead shields 34 and 34a fixed to the frame. The space between the two shields forms a window 3-5. Shutter 29 has a first position in which its shield '34- covers opening 17 in the X-ray head 15, a second position in which its window 35 exposes this opening, and a third position in which its other shield 34a covers the opening. The shutter is driven from a Selsyn motor 36 mounted on bracket 28. Motor 36 is connected to the shutter via a speed reducer 37, a spur gear 38, and a gear segment 39 fixed to hub 30 and meshing with the spur gear.

We energize the Selsyn motor 36 from a transmitter 40 mounted on carriage 20 beneath cradle 24 (FIGURE 1). We drive this transmitter from the shaft on which the drive pinion 22 is mounted through a chain and sprocket connection 41 and an electric brake and clutch device 42. Normally the brake of the latter device is set and the clutch disengaged, whereby the transmitter 49 and motor 36 do not operate and shutter 29 remains stationary. When the brake is released and the clutch engaged, as hereinafter explained, the transmitter moves proportionally to the carriage, both as to magnitude and direction. Motor 36 undergoes similar movement, whereby it drives the shutter at the same speed and in the same direction as pipe P is traveling.

We employ photoelectric means for controlling our brake and clutch device 42 and thus controlling operation of our Selsyn transmitter 49 and movement of our shutter. As shown in FIGURE 3, we mount first and second light sources 43 and 43a on the X-ray head 15 approximately in line with the respective side edges of opening 17. The mounting means includes a circular clamp 4 fixed to the X-ray head, and an elongated bracket 45 fixed to the upper edge of the clamp. Bracket 45 has slots 46 and 46a in which the respective light sources 43 and 43:: are mounted for horizontal adjustment to regulate the exact points at which the shutter operates. The light sources direct light beams at first and second photocells 47 and 47a respectively located outside the pipe (shown only in the schematic diagram of FIG- URE 4).

FIGURE 4 shows schematically our preferred control circuit. This circuit includes lines 5% and 51 connected to a suitable power source, brake and clutch coils 52 and 53 embodied in the brake and clutch device 42, and relays A, B and C. Relay A has back and front contacts A and A and its coil is connected to the first photocell 47, whereby the relay picks up when the photocell is exposed to light from the light source 43 but otherwise drops out. Relay B has back and front contacts B and B and its coil is connected in a similar relation to the second photocell 47a. Relay C has back contacts C connected in series with the brake coil 52 across lines 53 and 51, and front contacts C connected in series with the clutch coil 53 across these lines. Thus the brake coil 52 remains energized and the Selsyn transmitter 40 does not operate as long as relay C is not energized and its back contacts C remain closed. When relay C picks up and its front contacts C close, the clutch coil 53 is energized and the Selsyn transmitter operates.

The coil of relay C is connected in series with the back contacts A and the front contacts B across lines 59 and 51, and also in series with front contacts A and back contacts B whereby relay C can be energized via either set of contacts. As long as pipe P breaks neither light beam, both relays A and B are energized, their back contacts A and B are open, and relay C is deenergized. When the leading end of pipe P, moving from right to left as viewed in FIGURE 3, breaks the beam to photocell 47, relay A drops out, its back contacts A close, and relay C picks up via contacts A and B When the leading end breaks the beam to photocell 47a, relay B drops out, its front contacts B open and relay C drops out. Also the back contacts B close to condition the other current path to the coil of relay C. When the trailing end of the pipe exposes photocell 47, relay A again picks up, its front contacts A close, and relay C picks up via contacts A and 13;. When the trailing end exposes photocell 47a, relay B again picks up, its back contacts B open and relay C drops out. Relays A and B act in the reverse sequence when the pipe travels in the opposite direction on its return.

Before carriage moves a pipe P toward the left over the X-ray head 15, the X-ray head and the light sources 43 and 43a are energized. Shutter 29 occupies its first position in which its shield 34 fully covers opening 17. When the leading end of the pipe commences to cover opening 17, it also breaks the light beam to photocell 47, whereupon the shutter automatically moves counterclockwise in synchronism with the leading end of the pipe and progressively exposes the end portion of weld W to X-rays emitted through opening 17. As the shutter reaches its second posiiton in which its window 35 fully exposes opening 17, the leading end of the pipe breaks the light beam to photocell 47a, whereupon the shutter stops. As the trailing end of the pipe subsequently exposes photocell 47, the shutter automatically moves counterclockwise in synchronism with the trailing end, and its shield 34a progressively covers opening 17 as the trailing end exposes it. As the shutter reaches its third position in which its shield 34a fully covers opening 17, the trailing end exposes photocell 47a, whereupon the shutter stops. The reverse action takes place as the pipe moves back from left to right. Thus the inspector is able to observe both end portions of the weld while the shields 34- and 34a eliminate glare as the ends of the pipe pass opening 17. Normally we adjust the positions of the light sources 43 and 43a in bracket 45 so that the shields have a lap of about /2 inch over the pipe ends, since the ends are cropped to this extent. Nevertheless we can adjust the parts to avoid any lap and inspect the entire weld.

From the foregoing description it is seen that our invention affords a simple shutter, and an operating mechanism which automatically moves the shutter in synchronism with an article as the ends of the article pass a ray-directing means. As applied to a pipe inspecting apparatus, our invention enables a weld to be inspected throughout its length while the pipe continues in motion. Our shutter is readily installed on existing equipment, and it enables the equipment to perform a more rigid inspection and to include the most critical portions of a weld.

While we have shown and described only a single embodiment of the invention, it is apparent that modifications may arise. Therefore, we do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

We claim:

1. in an apparatus which includes means for directing rays on an article traveling relatively thereto, the combination therewith of a shutter mounted for movement to different positions in which it covers or exposes said raydirecting means, and a drive mechanism operatively connected with said shutter for moving the shutter in synchronism with the relative movement of the article at the same speed and in the same direction for covering the portion of said ray-directing means left exposed as at least one end of the article passes thereover.

2. In an apparatus which includes means for directing rays on an article traveling relatively thereto, the combination therewith of a movable shutter, which in the absence of an article normally covers said ray-directing means and in the presence of an article normally exposes said ray-directing means, and a drive mechanism operatively connected with said shutter for moving the shutter in synchronism with the relative movement of the article at the same speed and in the same direction for covering the portion of said ray-directing means left exposed as the ends of the article pass thereover.

3. In an X-ray pipe-inspecting apparatus which includes a support, an X-ray head mounted on said support, and means for relatively moving a pipe over said head, the combination with said head of a shutter movably mounted on said support, and a drive mechanism operatively connected with said shutter for moving the shutter in synchronism with the relative movement of the pipe for partially covering said head as at least one end of the pipe passes thereover.

4. In an X-ray pipeinspecting apparatus which includes a support, an X-ray head mounted on said support, and means for relatively moving a pipe over said head, the combination with said head of a shutter mounted on said support for movement to different positions in which it covers or exposes said head, and a drive mechanism operatively connected with said shutter for moving the shutter in synchronism with the relative movement of the pipe for covering the portion of said head left exposed as at least one end of the pipe passes thereover.

5. In an X-ray pipe-inspecting apparatus which includes a support, an X-ray head mounted on said support, and means for relatively moving a pipe over said head, the combination with said head of a shutter movably mounted on said support, said shutter in the absence of a pipe normally covering said head and in the presence of a pipe normally exposing said head, and a drive mechanism mounted on said support and operatively connected with said shutter for moving the shutter in synchronism with the relative movement of the pipe for covering the portion of said head left exposed as the ends of the pipe pass thereover.

6. In an X-ray pipe-inspecting apparatus which includes a support, an X-ray head mounted on said support, and means for relatively moving a pipe over said head, the combination with said head of a shutter movably mounted on said support, said shutter in the absence of a pipe normally covering said head and in the presence of a pipe normally exposing said head, a drive mechanism mounted on said support and operatively connected with said shutter for moving the shutter in synchronism with the relative movement of the pipe to expose and cover said head, and photoelectric means for actuating said drive mechanism as the ends of a relatively moving pipe reach and later clear said head, whereby said shutter covers the portion of said head left exposed by the pipe as its ends pass thereover.

7. In an X-ray pipe-inspecting apparatus which includes a support, an X-ray head mounted on said support, and means for relatively moving a pipe over said head, the combination with said head of a shutter movably mounted on said support and having a pair of spaced apart shields and a window between said shields, said shutter in the absence of a pipe normally occupying a position in which one of said shields covers said head and in the presence of a pipe a position in which said window exposes said head, a drive mechanism mounted on said support and operatively connected with said shutter for moving the shutter in synchronism with the relative movement of the pipe to expose and cover said head, and means for actuating said drive mechanism as the ends of a relatively moving pipe reach and later clear said head, whereby one of said shields moves in advance of the leading end of the pipe and the other shield moves behind the trailing end to cover the portion of said head left exposed by the pipe as its ends pass thereover.

8. In an X-ray pipe-inspecting apparatus which includes a support, an X-ray head mounted on said support, and a cooperating carriage for moving a pipe over said head, the combination with said head of a shutter movably mounted on said support and having a pair of spaced apart shields and a window between said shields, said shutter in the absence of a pipe normally occupying a position in which one of said shields covers said head and in the presence of a pipe a position in which said window exposes said head, a motor mounted on said support for driving said shutter, a transmitter mounted on said carriage and operatively connected thereto for energizing said motor and thus moving said shutter in synchronism with the pipe to expose and cover said head, and means for actuating said transmitter as the ends of a pipe reach and later clear said head, whereby one of said shields moves in advance of the leading end of the pipe and the other shield moves behind the trailing end to cover the portion of said head left exposed by the pipe as its ends pass thereover.

9. In an X-ray pipe-inspecting apparatus which includes a support, an X-ray head mounted on said support, and a cooperating carriage for moving a pipe over said head, the combination with said head of a shutter pivotally mounted on said support and having a pair of spaced apart shields and a window between said shields, said shutter in the absence of a pipe normally occupying a position in which one of said shields covers said head and in the presence of a pipe a position in which said window exposes said head, a motor mounted on said support and connected to said shutter for swinging the shutter to its different positions, a transmitter mounted on said carriage and operatively connected thereto for energizing said motor and thus swinging said shutter in synchronsim with movement of the pipe to expose and cover said head, and photoelectric means for actuating said transmitter as the ends of a pipe reach and later clear said head, whereby one of said shields moves in advance of the leading end of the pipe and the other shield moves behind the trailing end to cover the portion of said head left exposed by the pipe as its ends pass thereover.

10. A combination as defined in claim 9 in which said photoelectric means include a pair of spaced apart light sources carried by said head and a pair of corresponding photocells outside the pipe, whereby passing of the ends of the pipe controls said photocells.

References Cited in the file of this patent UNITED STATES PATENTS 2,360,036 Boucher Oct. 10, 1944 2,370,163 Hare Feb. 27, 1945 2,788,896 Coleman Apr. 16, 1957 2,856,539 Orthuber Oct. 14, 1958 2,858,450 Holben Oct. 28, 1958 2,894,140 Schneeman July 7, 1959 2,951,159 Mariner Aug. 30, 1960 2,965,758 Malick Dec. 20, 1960 2,981,845 Larew et al Apr. 25, 1961

Claims (1)

1. IN AN APPARATUS WHICH INCLUDES MEANS FOR DIRECTING RAYS ON AN ARTICLE TRAVELING RELATIVELY THERETO, THE COMBINATION THEREWITH OF A SHUTTER MOUNTED FOR MOVEMENT TO DIFFERENT POSITIONS IN WHICH IT COVERS OR EXPOSES SAID RAYDIRECTING MEANS, AND A DRIVE MECHANISM OPERATIVELY CONNECTED WITH SAID SHUTTER FOR MOVING THE SHUTTER IN SYNCHRONISM WITH THE RELATIVE MOVEMENT OF THE ARTICLE AT THE SAME SPEED AND IN THE SAME DIRECTION FOR COVERING THE PORTION OF SAID RAY-DIRECTING MEANS LEFT EXPOSED AS AT LEAST ONE END OF THE ARTICLE PASSES THEREOVER.

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