US3546414A - Gages for aligning workpieces in an electroerosive flaw-cutting machine - Google Patents

Description

I United States Patent 1 3,546,414

[72] Inventor William L. Zemberry [56] References Cited Swhmle Borough, Pennsylvania UNITED STATES PATENTS P 2,502,660 4/1950 McLean 33/21x c [221 1968 3,097,434 7/1963 Diamond 33/181 [451 fi 3,247,599 4/1966 O'Connor 33/185 [731 Awgn smlcmpmm" 3,335,255 8/1967 Ebersole m1. 2l9/69(V)UX a corporation of Delaware Primary Examiner--R. F. Staubly Attorney-Walter P. Wood ABSTRACT: A method and apparatus for aligning a cylindrical workpiece in a machine which electroerosively cuts GAGES FOR ALIGNING WORKPIECESINAN circumferential simulated flaws. workpiece forms a stand- ELECTROEROSWE FLAW'CUTTING MACHINE ard specimen to be used in calibrating a flaw-detection de- 3 Chhm16nnwin3 Figs vice. Longitudinal, horizontal and vertical diametrical guide [52] U.S.Cl. 219/69; lines are marked on the workpiece. Longitudinal and cir- 33/21 cumferential positioning gages are installed successively on [51] Int. Cl. 823p 1/08 and in alignment with the free end of a horizontally disposed [50] Field ofSeareh 219/68, and vertically swingable electrode arm, and the workpiece 69(E,M),69(F,V),69(G),6l; 33/2l(C), 181, 185 adjusted to position the guide lines on these gages.

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SHEET 2 BF 2 11v van ran. WILLIAM L. zzn asnnr A r ramey either on the outside surface or the GAGES FOR ALIGNING WORKPIECES IN AN ELECT ROEROSIVE FLAW-CU'I'IING MACHINE SPECIFICATION This invention relates to an improved method and gauges for aligning a round workpiece in a machine which cuts circumferential simulated flaws.

Certain types of metal products are inspected for internal discontinuities by ultrasonic, eddy-current, fringe-flux or analogous systems. Before actually inspecting the product, the inspector must adjust the test equipment to the desired sensitivity, using standard specimens which contain simulated flaws of known dimensions. Machines are available commercially for cutting extremely thin shallow simulated flaws in workpieces to form standard specimens. If the simulated flaw is to be cut circumferentially in a round workpiece, it is difficult to align the workpiece to obtain a flaw of the' necessary uniform depth concentric with the central axis.

An object of my invention is to provide an improved method and gauges for aligning a round workpiece in a simulated flaw-cutting machine to enable the machine to cut an accurate circumferential flaw.v

A further object is to provide a method and gauges of the foregoing type which align theworkpiece for cutting a flaw inside surface of a hollow workpiece, such as a pipe.

In the drawings:

FIG. 1 is a partly diagrammatic front elevational view of a flaw-cutting machine equipped with a gauge of my invention;

FIG. 2 is a vertical section on line II-II of FIG. 1;

FIG. 3 is a front elevational view on a larger scale and partly in section of the gauge shown in FIG. 1;

FIG. 4 is an elevational'view on line lV-IV of FIG. 3;

FIG. 5 is a view similar to FIG. 3, but showing a different form of gauge; and

FIG. 6 is a vertical section on line Vl-Vl of FIG. 5.

FIGS. 1 and 2 show diagrammatically a portion of a conventional flaw-cutting machine which includes a stationary face plate 12, and a feed arm 13 pivoted at its lower end to the face plate, as indicated at 14. An electrode arm 15 is rigidly fixed to the lower end of the feed arm near the pivot. The electrode arm extends approximately at right angles to the feed arm and is' electrically insulated therefrom. The end of the electrode arm carries a thin electrode shim l6, hereinafter described in more detail. The feed arm carries a terminal 17 for a power input lead to the electrode arm. The upper portion of the face plate carries a feed screw mechanism 18 and a spring feed mechanism 19 at opposite sides of the feed arm 13. A dial micrometer 25 is fixed to the face plate and connected to the feed arm. The machine as thus far described (apart from the electrode shim) is similar to'that shown in my application Ser. No. 455,858, filed May 14, 1965 (now U.S. Pat. No. 3,400,238). Hence I have abbreviated the description in the present application.

As FIG. 3 shows, the electrode arm 15 carries a transverse disc 26 preferably welded thereto and spaced from its free end. The disc carries an alignment pin 27 projecting from its face. The longitudinal axes of pin 27 and arm 15 lie accurately in the same vertical plane. The electrode shim 16 fits over the electrode arm 15 and pin 27, and is removably clamped in place by a clamping disc 28 and nut 29. As distinguished from my earlier application, the shim extends transversely of the electrode arm for cutting a circumferential flaw in either the outside or inside surface of a tubular workpiece S. The shim has holes which receive the electrode arm 15 and pin 27, the centers of the holes being on the vertical centerline of the shim. The shim is cut accurately so that it is symmetrical with respect to its vertical centerline. A shim with a concave lower edge is used for cutting a flaw' in the outside surface, while a shim with a convex lower edge is used for cutting a flaw in the inside surface. In either instance the shim projects a sufficient distance below the discs 26 and 28 to contact and penetrate the workpiece to the desired depth.

As FIGS. 1 and 2 show, the workpiece S is clamped to a table 30 which is adjustable with respect to arm 15 along three mutually perpendicular axes X, Y and Z. The mechanism for supporting and moving the table is not illustrated, since such mechanism is well known and not part of my invention. Each clamp for holding the workpiece on the table includes a block 31 attached to the table with T-bolts 32, the heads of which are received in a lengthwise groove 33 in the table top. The upper face of block 31 has a V-groove 34 which receives the workpiece. The block also carries an upwardly extending arm 35 which overhangs the workpiece and has a clamp screw 36 engageable with the top of the workpiece.

Before cutting a circumferential flaw in the outside surface of the workpiece S, I mark a longitudinal guideline 37 along its upper surface parallel with the central axis, and diametric horizontal and vertical guidelines on its end face. The vertical guideline, indicated at 38 in FIGS. 4 and 6, intersects the longitudinal guideline. Even though the flaw is to be cut in the inside surface, I mark the longitudinal guideline on the outside surface. To obtain a concentric circumferential flaw of uniform depth, it is critical that the flaw is symmetrical with respect to the longitudinal guideline 37. This necessitates aligning the workpiece accurately with respect to the electrode arm 15 both longitudinally and circumferentially.

In accordance with my invention, the electrode arm 15 carries a mandrel 39 extending from its free end. I install a longitudinal positioning gauge 40 on this mandrel. Gauge 40 includes an elongated body. 41 and two parallel pointers 42 depending from the body radially with respect thereto. The end face of body 41 has a socket 43 which receives mandrel 39. I fix the gauge on the mandrel with a lock pin 44 which extends through aligned vertical openings in the gauge body and mandrel. I clamp the workpiece S loosely in the block 31 with the vertical guideline 37 approximately vertical, adjust the table 30 in the direction of the Z axis (that is, horizontally and transversely of the electrode arm 15) to position the longitudinal guideline 37 exactly under the two pointers 42, and remove the gauge 40.

After I align the workpiece in this fashion, the vertical guideline 38 may still be slightly off a true vertical position. Next in accordance with my invention, I install a circumferential positioning gauge 45 on mandrel 39. Gauge 45 includes a body 46 which has a pointer 47 at its free end. The other end of body 46 has a socket 48 which receives mandrel 39. I adjust the table 30 in the X and Y directions to a position in which the guideline 38 at the bottom of the pipe is approximately aligned with the pointer 47. If the pointer does not meet this guideline, I adjust the workpiece in its clamps to a position in which it does meet. I then repeat the operation with the longitudinal positioning gauge 40, and continue such operations until both gauges indicate the workpiece is aligned accurately. If the flaw is to be cut on the inside surface of a pipe, I follow the same procedure, since the inside and outside surfaces are concentric within close tolerances.

Thereafter 1 tighten the clamp screw 36, and adjust the table in the X and Y directionsto place the shim 16 across the longitudinal guideline. I operate the machine in the usual way to cut a simulated flaw in the workpiece. Since the shim itself is constructed and mounted accurately to be symmetrical with respect to the longitudinal axis of the electrode arm, the cut is concentric and of uniform depth. I may follow a procedure similar to that shown and claimed in my aforementioned patent to measure and control the flaw depth, except that the gauge wire extends in a direction perpendicular to that shown in the patent.

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

Iclaim:

1. The combination, with a machine for cutting circumferential simulated flaws in the surface of an elongated cylindrical workpiece, said machine including an electrode arm movable up and down, a transverse disc carried by said am, a pin extending from said disc having its longitudinal axis in the same vertical plane as said arm, a symmetrical electrode shim mounted on said arm and pin and having an arcuate cutting edge, a table adjustable with respect to said arm along three mutually perpendicular axes, and means on said table for clamping a workpiece thereon with its longitudinal axis disposed horizontally, said workpiece having straight intersecting longitudinal and vertical guidelines marked thereon, of longitudinal and circumferential positioning gauges to be mounted successively on said arm for aligning said workpiece with respect to said arm, said longitudinal positioning gauge including a body extending parallel with the axis of said arm and a pair of parallel pointers depending radially from said body to lie exactly on said longitudinal guideline, and a circumferential positioning gauge including a body extending parallel with the axis of said arm and a pointer on the end of said last-named body to meet said vertical guideline.

guideline. a

2. A combination as defined in claim '1' in which said electrode arm has a mandrel extending from its end, and said gauges have sockets in their ends to receivesaid mandrel.

3. A combination as defined in claim 2in which said longitudinal positioning gauge is fixed to said mandrel with a radi ally extending lock pin.

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