US3689829A

US3689829A - Orbital flaw detector with radially aligned fluid actuators with means to counteract centrifugal forces

Info

Publication number: US3689829A
Application number: US106217A
Authority: US
Inventors: John S Miller
Original assignee: WEAN IND Inc
Current assignee: WEAN IND Inc
Priority date: 1971-01-13
Filing date: 1971-01-13
Publication date: 1972-09-05
Anticipated expiration: 1989-09-05

Abstract

An orbital tester for detecting flaws in elongated, round metal workpieces, comprising a rotatable face plate having a central opening through which the workpiece passes in longitudinal manner, a pair of probe members having search coils engageable with opposed surfaces of the workpiece, a pair of diametrically opposed main fluid cylinders carried by the face plate and having connection with the probe members to press their search coils into engagement with workpiece surfaces, and further cylinders at the side of said main cylinders. The pistons of the main cylinders have rack and gear connection with the pistons of the side cylinders, the connections being so constructed and arranged that as the pistons in the side cylinders move in one direction, the pistons in the main cylinders move inthe opposite direction.

Description

United States Patent Miller [4s] Sept. 5, 1972 [54] ORBITAL FLAW DETECTOR WITH RADIALLY ALIGNED FLUID ACTUATORS WITH MEANS TO COUNTERACT CENTRIFUGAL FORCES [72] Inventor: John S. Miller, Poland, Ohio 3,281,667 10/ 1966 Dobbins et a1 ..324/40 Primary Examiner-Robert J. Corcoran Attorney-Michae1 Williams ABSTRACT An orbital tester for detecting flaws in elongated, round metal workpieces, comprising a rotatable face plate having a central opening through which the workpiece passes in longitudinal manner, a pair of probe members having search coils engageable with opposed surfaces of the workpiece, a pair of diametrically opposed main fluid cylinders carried by the face plate and having connection with the probe members to press their search coils into engagement with workpiece surfaces, and further cylinders at the side of said main cylinders. The pistons of the main cylinders have rack and gear connection with the pistons of the side cylinders, the connections being so constructed and arranged that as the pistons in the side cylinders move 10 Claims, 6 Drawing figures PATENTEDSEP 5 m2 sum 1 0F 2 INVENTOR. O 5\M\\ LER A T TORNEy ORBITAL FLAW DETECTOR WITH RADIALLY ALIGNED FLUID ACTUATORS WITH MEANS TO COUNTERACT CENTRIFUGAL FORCES BACKGROUND AND SUMMARY My invention provides an improved orbital testing device which is statically and dynamically balanced for most efficient operation. The testing device includes fluid cylinder means for pressing the search coils against the workpiece and means for opposing centrifugal force which tends to separate the search coils.

Heretofore, as far as I am aware, pivoted weights were utilized to counteract centrifugal force and such prior construction was cumbersome and required considerable operating area, and was difficult to maintain in balance.

In contrast, my invention provides a pair of diametrically opposed mechanisms, which are held to straight line movement. These mechanisms require less space, are easily maintained and provide a trim appearance.

DESCRIPTION OF THE DRAWINGS In the drawings accompanying this description and forming a part of this specification, there is shown, for purpose of illustration, an embodiment which my invention may assume, and in these drawings:

FIG. 1 is a front face view of an orbital testing device, illustrating a presently preferred embodiment of my invention,

FIG. 2 is a sectional view corresponding to the line 2-2 of FIG. 1,

FIGS 3 and 5 are fragmentary, enlarged sectional views corresponding respectively, to the lines 3-3, and 5-5 of FIG. 1,

FIG. 4 is a sectional view corresponding to the line 4-4 of FIG. 5, and

FIG. 6 is an enlarged sectional view corresponding to the line 6-6 of FIG. 3.

DESCRIPTION OF PREFERRED EMBODIMENT As seen in FIGS. 1 and 2, a circular face plate 10 is supported for rotation in any suitable manner, such as by means of a hub 11 secured to its rear face and supported in suitable bearings (not shown). The face plate has a central opening 12 through which an elongated cylindrical workpiece 14 may be moved in a direction transverse of the face plate. The workpiece 14 is the object to be tested for flaws, and may be supported in any suitable manner and fed longitudinally in a controlled manner while it is rotated about its longitudinal axis. Flaw detecting probe members 15-15 are adapted to be pressed against opposite surfaces of the member 14 and are electrically connected to mechanism, not shown but known in the prior art, to indicate flaws in the workpiece 14. The probe members 15 are also of known construction and per se form no part of my invention. It is therefore sufficient to state that each probe member comprises a housing 16 containing search coils 17 which are spring-pressed outwardly of the housing a limited amount. As shown in FIG. 2, the search coils 17 of each housing are in pairs in order to extend the longitudinal length of the workpiece 14 to be inspected.

Similar mechanisms

18 and 19 are carried by the front face of the plate 10 and are so constructed and arranged that the latter is statically and dynamically balanced and provides support for the detecting probe members 15 so that the latter accurately track the workpiece 14 at all times.

Each

mechanism

18 and 19 includes a cluster of three fluid cylinders, with main cylinders 20 arranged in diametrically opposed relation, as seen in FIG. 1, and with similar side cylinders 21-21 arranged parallel to and on opposite sides of the main cylinders. Each cylinder 20 and its side cylinders 21 are transversely arranged in triangular fashion, as seen in FIG. 5, in order to provide for operating mechanism to be described. Each cylinder 20 comprises a barrel 22 which has its end remote from the center of the face plate closed by a cap 23. The cap is formed with an opening 124 for fluid under pressure from a suitable source. Each side cylinder 21 comprises a barrel 24 which has its end remote from the center of the face plate closed by a cap 25. This cap is also formed with an opening 26 for fluid under pressure from a source. The inner end of each barrel 24 is closed by a cap 27.

Each cluster of cylinders 20 and 21-21 is supported by a pair of

brackets

30,31 which are bolted to the front face of the plate 10. The barrels 22 and 24-24 extend through openings in the brackets and may be secured therein in any suitable manner, such as by welding.

A piston 32 is slidable within each barrel 22 and is provided with a packing 33 on its end remote from the center of the face plate 10. The opposite end of the piston has a rod 34 extending therefrom to a swivel connection 35 with a respective probe housing 16. Parts of the piston 32 and rod 34 are recessed to closely receive a gear rack 36, the latter being held in position by machine screws 37. The rack 37 meshes with a gear 38 keyed to the central portion of a shaft 39'(see especially FIG. 6).

A piston 40 is slidable within each of the side barrels 24-24 and is provided with a packing 41 on its end remote from the center of the face plate 10. Each piston is recessed to closely receive a gear rack 42, the latter being held in position by machine screws 43. Each gear rack 42 meshes with a respective one of a pair of gears 44 keyed to end portions of the shaft 39. Each bracket 30 forms a housing for a respective shaft 39 and gears 38 and 44-44 keyed thereto. End portions of the shaft 39 are supported in needle bearings 45 which in turn are supported by sleeves 46 having end caps 47 which are bolted to opposite sides of the bracket 30. Thus, the assembly just described may be inserted from either end of the opening 48 in the bracket 30.

From the foregoing, it will be appreciated that the rack and gear connections will connect the piston 32 with the side pistons 40-40 so that when the pistons 40-40 are moved toward the center of the face plate 10, as when fluid under pressure is admitted through the openings 26 in end caps 25, the piston 32 will simultaneously be moved in a direction away from the center of the face plate 10, so that the probes 15-15 may be separated for insertion of a workpiece 14 therebetween. In the illustrated embodiment, the gear 38 is twice the diameter of the side gears 44-44 so that the piston 32 travels twice the amount of the pistons 40-40.

As seen in FIG. 1 and 2, the housing 16 of each probe member 15 has a pair of struts 50 connected thereto, as by welding, and extending therefrom in diverging manner. The ends of the struts 50 are connected, as by welding, to respective barrels of ball bushings 51, and the latter move longitudinally along respective rods 52, supported at one end in brackets 53 bolted to the face plate 10, and at their other ends in a central bracket 54 which is also bolted to the face plate. Thus, the respective probe members 15 are accurately guided along a diametrical line, while the connections 35 permit limited alignment for the rods 34 of the cylinders 20.

In operation, fluid under pressure is admitted to the barrels 2424 through openings 26 in the end caps 25 to drive the pistons 40 in a direction toward the center of the face plate 10. This causes the pistons 32 to move in the opposite direction to separate the probe members 15-15 and permit a workpiece 14 to be inserted therebetween. Thereafter, fluid under pressure may be admitted to the barrels 22 through the openings 124 in end caps 23 while fluid is exhausted from the barrels 2424, to drive the pistons 32 toward the center of the face plate. The fluid pressure in the barrels 22 may be regulated in any suitable manner so that the search coils are pressed into engagement with the workpiece with sufficient pressure to compress their backing springs.

The face plate is then rotated by any suitable drive and the work piece 14 is fed longitudinally and rotated axially. The search coils 17 induce a magnetic flux in the workpiece and flaws therein will effect this flux and may be recorded in any suitable manner. The face plate 10 may carry marking means (not shown but of conventional construction) to visibly mark the workpiece at the flaws.

l-leretofore, as the face plate rotated, centrifugal force would tend to lift the search coils from the surface of the workpiece and thus result in unreliable flaw detection. In the present invention, as the masses represented by the opposed pistons 32-3 2, and parts carried thereby, tend to move away from the center of the face plate due to centrifugal force, the mass represented by pairs of side pistons 4040 also tends to move out by centifugal force and, through the rack and gear connections, thereby oppose outward movement of the pistons 32 and therefore holds the search coils in proper engagement with the workpiece surfaces.

The mass of the pairs of pistons 40-40 may be made equal to the mass of the pairs of pistons 32 and parts carried thereby, so that an equal opposition to centrifugal force on the pistons 32 is effected. In some cases it may be desirable to maintain a certain amount of fluid under pressure in the cylinders 21-21, in addition to fluid pressure in the cylinders 20, to accurately control the amount of force applied to the probe members -15 to hold their search coils in engagement with the work surface.

I claim:

1. Apparatus for inspecting elongated cylindrical metal workpieces for flaws therein, comprising a rotatable face plate having a central opening through which a workpiece may be longitudinally moved in a direction transverse of said face plate, a pair of diametrically opposed detecting probe members adapted to engage opposed sides of said workpiece, a pair of diametrically opposed fluid cylinders carried by said face plate each cylinder having a fluid opening in that end which is remote from the center of said face plate to admit fluid under pressure into said outer end and thereby drive pistons in respective cylinders toward said face plate center, each piston having connection with a respective probe member for urging the latter into engagement with opposed surfaces of said workpiece when said pistons are moved toward the center of said face plate, and a pair of means connected to respective pistons and opposing movement of the latter in a direction away from said face plate center when the latter is influenced by centrifugal force established during rotation of said face plate said means being disposed in diametrically opposed relation to each other and each being slidably carried by said face plate for parallel movement with a respective piston.

2. The construction according to claim 1 wherein the connection between said last named means and said pistons causes relative movement between the same to vbe in opposite directions.

3. The construction according to claim 1 wherein said last named means comprises a pair of weight members.

4. The construction according to claim 3 wherein each of said weight members is a piston within a fluid cylinder.

5. The construction according to claim 4 wherein each weight member piston has gear connection with the respective piston of the first named fluid cylinders.

6. The construction according to claim 5 wherein said gear connection is a rack and pinion connection so constructed and arranged that the weight member pistons and the associated piston of the first named fluid cylinders are caused to move in opposite directions.

7. The construction according to claim 3 wherein each of said weight members comprises a pair of pistons movable in cylinders whichare disposed on laterally opposite sides of respective ones of said first named fluid cylinders.

8. Apparatus for inspecting elongated cylindrical metal workpieces for flaws therein, comprising a rotatable circular face plate having a central opening through which a workpiece may be longitudinally moved in a direction transverse of said face plate, a pair of diametrically opposed detecting probe members adapted to engage opposed sides of said workpiece, and a pair of diametrically opposed similar mechanisms carried by said face plate, each mechanism including a main fluid cylinder and a pair of fluid cylinders similar to each other and disposed in parallel relation to and on opposite sides of said main cylinder, pistons in each of said cylinders and each piston having a gear rack attached thereto, a shaft carrying gears meshing with respective racks, and so constructed and arranged that as the piston in said main cylinder moves toward the center of said face plate, the pistons in said similar cylinders move away from said center and vice versa, each piston of said main cylinder having connection with a respective probe member to move the same toward and away from the workpiece to be inspected.

9. The construction according to claim 8 wherein said main and similar fluid cylinders each has an opening in its end remote from the center of said face plate, and means for selectively admitting or exhausting fluid under pressure through said openings.

10. The construction according to claim 8 wherein said similar mechanisms are statically and dynamically 5 balanced.

Claims

2. The construction according to claim 1 wherein the connection between said last named means and said pistons causes relative movement between the same to be in opposite directions.

7. The construction according to claim 3 wherein each of said weight members comprises a pair of pistons movable in cylinders which are disposed on laterally opposite sides of respective ones of said first named fluid cylinders.

10. The construction according to claim 8 wherein said similar mechanisms are statically and dynamically balanced.