US3388235A

US3388235A - Vortex pressure control device

Info

Publication number: US3388235A
Application number: US510910A
Authority: US
Inventors: Edward A Pinsley; Allan P Walch
Original assignee: United Aircraft Corp
Current assignee: RTX Corp
Priority date: 1965-12-01
Filing date: 1965-12-01
Publication date: 1968-06-11
Anticipated expiration: 1985-06-11

Description

219" 121 *1 mun uw June 11, 1968 E. A. PlNsLx-:Y ET AL 3,388,235

VORTEX PRESSURE CONTROL DEVICE Filed Deo. l, 1965 United States Patent Oce 3,333,235 Patented June 11, 1968 3,388,235 VORTEX PRESSURE CONTROL DEVICE Edward A. Pinsley, Glastonbury, and Allan P. Walch,

Manchester, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed Dec. 1, 1965, Ser. No. 510,910 8 Claims. (Cl. 219-121) This invention relates to pressure control devices such as can be used with workpiece out-of-vacuum electron beam welders in which it is desired to establish a low pressure region in the vicinity of an orifice or between an orifice and a surface.

More specifically, this invention relates to out-ofvacuum working or welding with electrons or charged particles wherein the electron beam itself must be generated in a vacuum or low pressure environment.

It is an object of this invention to provide a pressure control in the form of a gaseous barrier between the point of emission of charged particles used in working materials and the workpiece itself. One form of such a device is disclosed in Patent No. 3,156,811, issued November 10, 1964 to Frank W. Barry and entitled Gaseous Sealing Means in an Apparatus for Working Materials by a Beam of Charged Particles.

The above object and the means for achieving it will be readily apparent from the following description of the drawing in which:

FIGURE 1 is a schematic illustration of an electron beam gun and the vortex pressure control according to this invention.

FIGURE 2 is an enlarged detail illustration showing the beam emitting region of the apparatus.

FIGURE 3 is a modification of the FIGURE 2 arrangement.

FIGURE 4 is a transverse section of FIGURE 2 or 3 illustrating the vortex producing chamber.

Referring to FIGURE l, an evacuated beam generating chamber 10 is shown as having an electron gun 12 schematically and generally indicated therein. Any known electron beam or other charged particle generating devices may be utilized as is well known in the art. The electron beam travels along a path or axis shown at 14. The chamber 10 is defined by the Wall 16 which is spaced from another wall 18 thereby forming an intermediateV low pressure chamber 20.

The walls 16 of the chamber 10 terminate at their lower end in a tapered beam emitting exit 24 having an aperture 26. The beam exits through the aperture 26 and is .intended to impinge upon a workpiece 28.

In order to control the pressure in the region of the aperture 26, it is desirable t form some barrier between the atmospheric pressure in the region of the workpiece 28, the relative low pressure chamber 20 and the substantial vacuum in the beam penetrating chamber 10. To this end an annular manifold 30 is supplied with relatively high pressure fluid through the conduit 32 for emission through a plurality of

orifices

34 and 36. As seen in FIGURE 4, the

orifices

34 and 36 are positioned substantially tangential of the vortex region forming the secondary chamber 38. The multiplicity of orifices insures a uniform pressure distribution around the vortex and the electron beam axis such that a concentricity with respect to the beam is achieved. In other words, if the vortex were not properly centered, the lowest pressure core region would not coincide with the electron beam from its point of emission from the aperture 26 to the workpiece 28.

FIGURES 2 and 3 illustrate preferred embodiments of the invention. As seen in FIGURE 2, the beam aperture means 24 is surrounded by a collar or ramp 42 thereby forming a second aperture 44 surrounding the aperture means 24.

Since a high rate of diffusion is desired, the angle 0f the wall of the aperture means 24 may vary in the range of an included angle of more than 60 but less than Also, to obtain acceptable low density over the beam path 14, the minimum flow area formed by the walls 16 should be greater than 400 times the area of the beam orifice 36.

Of course this is speaking of the possible fiow being in a direction upstream of the beam since the beam generating chamber 10 has the lowest pressure of the device.

It should be noted that in the embodiment shown in FIGURE 2 the aperture 26 is located upstream along the beam axis relative to the lower lip 50 of the ramp 42. Tests have shown that although relatively more pumping is required via the chamber 20 in this configuration, a lower pressure is experienced at the aperture 26 even though the beam length to the workpiece is somewhat longer.

The modification shown in FIGURE 3 illustrates an arrangement whereby the aperture 26 is substantially coincident with the lip 50 of the ramp 42. In this configuration less pumping power is necessary as compared to the FIGURE 2 configuration. Also the external beam length is somewhat less that that shown in FIGURE 2.

As a result of this invention, it is apparent that a very simple but efficient mechanism has been provided whereby out-of-vacuum working can be produced with an electron beam device whereby the pressure between the workpiece and the point of emission of the electron beam can be suitably controlled. With a device of this nature a minimum of airflow can pass to the beam penetrating region to thereby maintain beam focusing and intensity. A vortex device of Vthis nature in combination with an electron beam emitting device maintains the beam emission aperture relatively clean of working contaminants.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described but may be used in other ways without departure from its spirit as defined by the following claims.

We claim:

1. A charged particle working device having a beam generating chamber, means in said chamber for generating a beam of charged particles, means for substantially evacuating said generating chamber to reduce the gaseous content thereof, aperture means in said chamber from which said beam may exit to a higher pressure region, aperture means including a diffuser section having its smaller area at the chamber exit and its larger area upstream of the generated beam, said larger area being greater than 400 times the area of said smaller area, said chamber surrounding said aperture means and tapering away therefrom, wall means surrounding said ramp and extending downwardly away from said chamber beyond said aperture means, said wall means forming a second chamber outside said beam generating chamber and exposed on one side to the atmosphere, and means for introducing a fluid into said second chamber and substantially tangentially of said wall to produce a vortex substantially surrounding said aperture means.

2. A device according to claim 1 wherein said second aperture is substantially aligned along the beam with respect to said aperture means and concentric therewith.

.3. A device according to claim 2 wherein the means for introducing fluid into said second chamber includes a plurality of passages in said wall means to insure uniformity of fiow distribution in said second chamber and concentricity of the core of said vortex with respect to the beam.

4. A device according to claim 3 wherein said ramp means includes a second aperture surrounding said aperture means.

5. A device according to claim 4 wherein said second aperture is connected to a relatively low pressure region below atmospheric.

6. A device according to claim 4 wherein said second aperture is spaced downstream along said beam with respect t said aperture means.

7. A device having a vacuum chamber, means for sub stantially evacuating said chamber to reduce the gaseous content thereof, aperture means in said chamber which exits to a higher pressure region, wall means radially spaced from and surrounding said aperture and extending downwardly away from said chamber beyond said aperture means, said wall means forming a second chamber outside said vacuum chamber, and means for intro` ducing a uid into said second chamber to produce a vortex substantially surrounding said aperture means.

8. A charged particle working device having a beam generating chamber, means in said chamber for generating a beam of charged particles, means for substantially evacuating said generating chamber to reduce the gaseous content thereof, aperture means in said chamber from which said beam may exit to a higher pressure region,

aperture means including a diffuser section having its smaller area at the chamber eXit and its larger area upstream of the generated beam, a ramp outside said chamber surrounding said aperture means and tapering away therefrom, wall means surrounding said ramp and eX- tending downwardly away from said chamber beyond said aperture means, said wall means forming a second chamber outside said beam generating chamber and exposed on one side to the atmosphere, and means for introducing a fluid into said second chamber and substantially tangentially of said wall to produce a vortex substantially surrounding said aperture means.

References Cited UNITED STATES PATENTS 1,638,336 8/1927 Himes.

3,156,811 11/1964 Barry 219-121 3,162,749 12/1964 Peracchio 2l9-121 3,171,943 3/1965 Niedzielski 219-121 3,175,073 3/1965 Niedzielski et al. 219-121 3,217,135 11/1965 Eklund 219-121 RICHARD M. l/VOOD, Primary Examiner'.

W. D. BROOKS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE O "atent No. 3,388 ,235 y June 11, 1965? Edward A. Pnsley et a1 It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as` shown below:

Column 2, line 63, claim reference numeral "1" shoul 1 :gi-CORRECTION t 4 line 66, claim reference numeral "Z" should @ad s m.

Signed and sealed ti's-r'l4th day of November 1969.

SEAL) Lttest:

ldward M. Fletcher, Jr.

Lttesting Officer WILLIAM E. SCHUTLER,- f

Commissioner of Pa v

Claims

1. A CHARGED PARTICLE WORKING DEVICE HAVING A BEAM GENERATING CHAMBER, MEANS IN SAID CHAMBER FOR GENERATING A BEAM OF CHARGED PARTICLES, MEANS FOR SUBSTANTIALLY EVACUATING SAID GENERATING CHAMBER T REDUCE THE GASEOUS CONTENT THEREOF, APERURE MEANS IN SAID CHAMBER FROM WHICH SAID BEAM MAY EXIT TO A HIGHER PRESSURE REGION, APERTURE MEANS INCLUDING A DIFFUSER SECTION HAVING ITS SMALLER AREA AT THE CHAMBER EXIT AND ITS LARGER AREA UPSTREAM OF THE GENERATED BEAM, SAID LARGER AREA BEING GREATER THAN 400 TIMES THE AREA OF SAID SMALLER AREA, SAID CHAMBER SURROUNDING SAID APERTURE MEANS AND TAPERING AWAY THEREFROM, WALL MEANS SURROUNDING SAID RAMP AND EXTENDING DOWNWARDLY AWAY FROM SAID CHAMBER BEYOND SAID APERTURE MEANS, SAID WALL MEANS FORMING A SECOND CHAMBER OUTSIDE SAID BEAM GENERATING CHAMBER AND EXPOSED ON ONE SIDE TO THE ATMOSPHERE, AND MEANS FOR INTRODUCING A FLUID INTO SAID SECOND CHAMBER AND SUBSTANTIALLY TANGENTIALLY OF SAID WALL TO PRODUCE A VORTEX SUBSTANTIALLY SURROUNDING SAID APERTURE MEANS.