US3156809A - Vapor deflector - Google Patents

Description

S'ILAHUH HUUWK.

Nov. 10, 1964 c. F. STEARNS VAPOR DEFLECTOR Filed April 9, 1962 mvszvron CHARLES E sum/vs av W0 0... l

AGENT United States Patent 3,156,809 VAPOR DEFLECTOR Charles F. Stearns, East 'Longmeadow, Mass., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed Apr. 9, 1962, Ser. No. 186,109 1 Claim. (Cl. 219--121) My invention relates to working materials with an intense beam of charged particles. More particularly, my invention relates to keeping the means through which the material being worked with such a beam is viewed from being rendered opaque by vapors released from the mate rial.

My invention has particular utility when used with an electron beam machine. Electron beam machines, as they are generally known, are devices which use the kinetic energy of an electron beam to work a material. U.S. Patent No. 2,793,281, issued May 21, 1957, to K. H. Steigerwald, discloses such a machine. These machines operate by generating a highly focused beam of electrons. The electron beam is a welding, cutting and machining tool which has practically no mass but has high kinetic energy because of the extremely high velocity imparted to the electrons. Transfer of this kinetic energy to the lattice electrons of the work pieces generates higher lattice vibrations which cause an increase in the temperature within the impingement area sufiicient to accomplish work. In fact, the temperature becomes so high that the material melts and even evaporates. This evaporation, in turn, permits deep penetration of the Work piece by the beam. That is, deep penetration can only be achieved by evaporation of a fine channel in the material.

In performing work with an electron beam, it is desirable to visually observe the material being worked. This may be accomplished by providing a leaded glass viewing port in the side of the electron beam machines vacuum chamber or, in machines where precision is desired, by providing an optical system including means for magnifying the image of the area being worked. US. Patent No. 2,944,172, issued July 5, 1960, to W. Opitz et al., discloses an electron beam machine having such an optical system including a microscope. Regardless of which approach to viewing is followed, a problem is presented by the condensation of the evaporated material on the window or protective glass of the viewing system. This deposit of vapor upon the surface of the viewing mechanism soon clouds this surface to an extent where it becomes impossible to observe the material being worked. This, in turn, necessitates a time consuming work stoppage for cleaning or replacing the clouded surface.

My invention overcomes the above stated problem by providing means for preventing vapors generated during an electron beam operation from condensing on the glass through which the work material is viewed.

It is, therefore, an object of my invention to prevent accumulation of deposits on the viewing surface of a machine which employes a beam of charged particles to work a material.

It is another object of my invention to eliminate the necessity for periodic cleaning of the means through which a material being worked with a beam of charged particles is viewed.

It is also an object of my invention to deflect vapors generated during a Welding operation away from a glass through which such operation is observed.

These and other objects of my invention are accomplished by placing an apparatus having a plurality of moving deflector blades between the material being worked and the means through which the work is observed. The apparatus of my invention is constructed so as to permit a beam of charged particles to pass through it in one ice direction to the material being worked while preventing vapors emanating from the work from passing through it in the opposite direction to the viewing means.

My invention may be better understood with reference to the accompanying drawing wherein like reference numerals refer to like elements in the different figures and in which:

FIGURE 1 is a cross-section view of an electron beam machine employing my invention.

FIGURE 2 is an enlarged sectional view of the embodiment of my invention utilized in FIGURE 1.

FIGURE 3 is a view along line 3-3 of the embodiment of my invention illustrated in FIGURE 2.

FIGURE 4 is an enlarged view of another embodiment of my invention which could be used with the machine shown schematically in FIGURE 1.

Referring now to FIGURE 1, an electron beam machine is shown having an electron gun chamber 10, a beam focusing column 12 and an evacuated work chamber 14. Inside electron gun chamber 10 there is a filament 16 for emitting electrons which are accelerated down column 12 by a difference in potential between filament 16 and anode 18. Surrounding filament 16 is a grid cup 20 which is biased at a voltage which is more negative than the voltage applied to filament 16. The magnitude of this bias controls the beam current while, due to the shape of the grid, also aiding in the focusing of the beam. The electrons which are accelerated down column 12 are focused into a narrow beam, indicated by reference numeral 22, by upper adjusting coil 24, lower adjusting coil 26, magnetic lens assembly 28 and upper and lower diaphragms 28 and 30. The beam 22 passes down a tube 31, which is suspended in column 12, into work chamber 14 where it impinges upon the work and consequently, gives up its kinetic energy in the form of heat. The material to be worked 30 may be moved beneath the beam by movable table 32 and the beam may be deflected over limited areas of the material by means of deflection coils 34. The material being worked is observed visually through an optical viewing system, part of which is not shown, comprising a viewing light 38 which is focused on the material by mirrors 40 and 42. The light path is shown as a dashed line 46. The image of the Work is transmitted back up the light path, reflected by mirrors 40 and 42, and transmitted via optical column 48 to a system including a microscope, not shown, wherein it is enlarged and viewed by an operator. Positioned between beam column 12 and optical column 48 is a piece of leaded glass 50 which protects the operator from X-rays generated during the electron beam operation.

Located in column 12 below mirrors 40 and 42 is a protective glass 44. The function of glass 44 is to prevent vapor emitted from the work piece from reaching the mirrors. Consequently, glass 44 will be the element which becomes coated and thus require cleaning or replacing unless my invention is used. Glass 44 must, of course, have a hole in its center to permit passage of the tube 31 therethrough. Positioned between glass 44 and the work material 30 is an apparatus, indicated generally by reference numeral 52, which prevents vapor from traveling up the beam column exteriorly of tube 31 to glass 44. This apparatus, which will be described below, is driven by a motor 54. The shaft of motor 54 passes into the vacuum chamber through a tubular member 56 which is supported from the top of the chamber by a web member 58.

Referring now to FIGURE 2 there is shown an enlarged view of the apparatus indicated generally by numeral 52 in FIGURE 1. Apparatus S2 is suspended at the lower end of beam column 12 by means of bolts 60. As illustrated in FIGURE 3, apparatus 52 comprises an outer ring 62 and an inner ring 64. A plurality of fan blades 66, 68, 70 and 72 are mounted between inner ring 64 and outer ring 62. As shown in FIGURE 2, the lower surface of outer ring 62 has gear teeth which form a bevel gear and which mesh with a gear 74 which is keyed to the end of shaft 76 of motor 54. Apparatus 52 also includes an outer, ring-shaped supporting member 78 which is held in fixed relationship to the beam column by bolts 60. The inner side of member 78 forms the outer race for ball bearings 80. Outer ring 62 forms the inner race for these bearings. The construction comprising rings 62 and 64 and the blades will rotate on these bearings when driven by motor 54 through gear 74. In the embodiment of FIGURES 2 and 3, the electron beam 22 passes down tube 31 and through inner ring 64 before impinging on 1 the material being worked. Any vapor passing up through inner ring 64 will travel up tube 31 and will, therefore, not collect on glass 44. Deflector blades 66, 68, 70 and 72 are slanted, as shown by the shading in FIGURES 2 and 3, and must be driven at a velocity such that any I 1 particle of vapor missing the trailing edge of one blade will hit somewhere between the leading and trailing edge of the next blade. The spaces between the blades will, however, allow passage of light and viewing of the work plece.

Referring now to FIGURE 4, there is shown an enlarged view of another embodiment of my invention which may be used with the machine shown schematically in FIGURE 1 when it is desired to work a material with a pulsed electron beam. The combination of rings and blades utilized with the embodiment of FIGURE 4 will be the same as that shown in FIGURE 3 with the exception that the various parts will be larger in diameter. In FIGURE 4, the speed of the rotating deflector blades is synchronized with the electron beam pulse, by means well known in the art, so that the beam may pass between the rotating blades. The vapor will be prevented from passing up to the beam column in the same manner as described above. To provide additional support for the larger assembly utilized in FIGURE 4, a bolt 82 is passed through inner ring 64 to the bottom of the electron beam column. Inner ring 64 rotates around bolt 82 on washers 84 and 86.

While preferred embodiments of my invention have been shown and described, various modifications and substitutions may be made without deviating from the scope and spirit of my invention. For example, the deflector blades of my invention might be located in the beam column directly below the protective glass. Also, my invention is equally advantageous when used to prevent clouding of a leaded glass viewing port in the side of the vacuum chamber. Thus, my invention is described by way of illustration rather than limitation and accordingly it is understood that my invention is to be limited only by the appended claim taken in view of the prior art.

I claim:

Apparatus for preventing metal vapor from clouding the means through which a welding operation being performed in a chamber is viewed comprising:

a ring shaped inner supporting member,

a ring shaped outer supporting member coaxial and coplanar with said inner member,

at least three deflector blades mounted between said inner and outer members, viewing means providing visual communication between the inside and outside of the chamber, means rotatably supporting said members and blades inside of the chamber between the articles being welded and said viewing means whereby the welding operation is viewed through the rotating blades,

gear means engaging said outer member for causing rotation of said members and blades about the common axis of said members, and

means sealably extending into the chamber for driving said gear means.

References Cited by the Examiner UNITED STATES PATENTS 2,514,990 7/50 Dewan 2l9l47 2,987,610 6/61 Steigerwald 2l9ll7 3,009,050 11/61 Steigerwald 2l969 RICHARD M. WOOD, Primary Examiner.

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