US2220910A - Method of producing cathode sleeves for thermionic valve - Google Patents

Description

Nov. 12, 1940. H; KERSHAW 2,220,910

METHOD OF PRODUCING CATHODE SLEEVES FOR THERMIONIC VALVES Originai Filed Jan. 25 1940 2 Sheets-Sheet 1 H. KERSHAW .Ndv. 12, 1946.

METHOD OF PRODUCING CATHODE SLEEVES FOR THERMIONIC VALVES Original Filed Jan. 23, 1940 2 Sheets-Sheet 2 -Patented Nov. 12, 1940 UNITED STATES LIETHOD OF PRODUCING CAT'HODE SLEEVES FOR THERMIONIO VALVES Henry Kershaw, Belleviile, N. J.

Original application January 23, 1940, Serial No.

315,250. Divided and this application February 2'7, 1940, Serial No. 321,125

13 Claims.

My invention relatesto a cathode sleeve for thermionic valves or vacuum tubes and to th method of producing the same.

In United States -Patent 2,029,482 a cathode 5 sleeve or cylinder is shown, formed from a strip of sheet metal, having its side edges interlocked, by providing oppositely facing bent tongues upon .the strip. These interlocking edges provide a seam of four layers of metal, and the seam is conl tinued beyond one end of thetub'e or cylinder to provide a tab, which is to be attached to a post. The tab is formed from spaced tab sections at one end of'the sheet and each of these tab sec-' tions is folded upon itself to provide a continuation of the interlocking tongues. Considerable difliculty is experienced, in producing this sleeve or cylinder with the tab, as shown in Patent 2,029,482, commercially, and the difficulty resides principally in the formation of the tab integral go with the sleeve or cylinder. As a result of this, these sleeves or cylinders rdinarily are produced without the tabs which are separate from the sleeve or cylinder and are subsequently welded to the sleeve or cylinder. This welding in place 25 of the tab is a separate operation and increases the cost of production of the product.

It has also been proposed to form the cathode sleeve or cylinder from an integral drawn tube and to provide a separate tab, which is subse- 30 quently welded to the drawn tube. This construction is shown in Patent 2,079,057. The drawn tube is expensive.

In accordance with my method, I form a sleeve having generally radially extending flanges, and 5 portions of these flanges contact but the flanges do not interlock, and these flanges are welded together. The sleeve may be accurately formed in the desired shape, such as circular, square, or other shape in cross-section, and the sleeve will not be distorted by the welding of the flanges. The welding of the flanges securely unite the side edges of the sleeve, and the welding may be effected rapidly and cheaply. This dispenses with the expensive practice of forming interlocking 45 tongues upon the side edges of the sleeve. In the practice of my method, the tab is formed of tab sections which are preferably in effect continuations of the flanges. Each tab section is singlelayer and portions of their faces contact but have 50 no interlocking engagement and are secured together by welding. The difiiculty experienced in shaping tab sections into interlocking tongues is therefore eliminated, and the tab may be readily produced integral with the sleeve or cylinder. I

55 may also bend over upon the sleeve or cylinder theoriginally generally radial welded flanges, providing a rib or seam. A portion of the welded flange may be left raised, for providing a shoulder. While it is preferred to bend down the welded flanges, the sleeve may be used without 5 doing this. A further advantage of my construction is that the rib or seam produced by the bentover welded flanges comprises but two layers of metal, thus effecting the maximum uniform distribution of heat. A further advantage of my construction is that the seam or rib may be arranged wholly upon the exterior of the sleeve, thus permitting of the close arrangement between the electrical heating unit and the sleeve, without liability of these elements contacting and scraping-off the insulationfrom the'.-heating....unit.

The present application is a continuation in part of my original application for Cathode sleeve for thermionic valves and method of producing the same, Serial No. 259,908, filed March 4, 1939, and my application for Cathode sleeve for thermionic valves, Serial No. 281,984, filed June 29, 1939, and which is a division of application 259,908. The present application is also a divi- On of application 315,250, filed Jan. 23, 1940 for Cathode sleeve for thermionic valves.

In the accompanying drawings forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a side'elevation, principally diagrammatic, illustrating apparatus used in the practice of the method for producing the cathode sleeve,

Figure 1 is a transverse section, parts broken away, taken. on line I* i of Figure 1,

Figure 2 is a perspective view of a portion of the ribbon or strip after being bent in the V- shape, 1

Figure 3 is a side elevation of the forming roll- 40 ers which bend the flat strip into the V-shape and produce the row of raised portions at one longitudinal edge of the ribbon or strip,

Figure 4 is a perspective view of the V-shaped strip having the tab sections forming opening 5 stamped therein,

Figure 5 is a transverse section through the stamping punch, in the lowered position, as if taken on line 5- 5 of Figure 1,

Figure 6 is a perspective view of the strip trans- 60 versely cut to provide the section or unit to form the cathode sleeve,

Figure 7 is a transverse section taken on line I-l f Figure 1, showing the cutter,

Figure 8 is a central longitudinal vertical sec- 'tion through the lower bed of the stamping and .holding device,

Figure 9 is a perspective view of the strip bent upon its longitudinal axis to partly form the-cathode sleeve,

Figure 10 is a transverse section through the forming die and mandrel and knock-down die, the partsbeing shown in the starting position,

Figure 11 is a similar view showing the forming die raised, the mandrel forced down, and the to provide strip bent about its longitudinal axis upstanding sides,

Figure 12 is an enlarged perspective view of the sleeve, with its flanges and tabs welded together,

Figure 13 is an end elevation of the welding jaws, in the closed position, illustrating the welding step for producing the sleeve shown in Figure 12, k

Figure 12" is an end elevation of the sleeve with the flanges slightly spaced and the raised portions engaging oneflange,

Figure 13 is an end elevation of the sleeve, showing the flanges contacting and welded togetnzr and indicating the dimensions of the pa Figure 1.4 is a bottom plan view of the welding Jaws,

Figure 15 is a perspective view of the sleeve, showing the welded flanges bent down sleeve and slit to form a stop shoulder,

Figure 16 is a transverse section through the knock-down punch showing the formation of the stop shoulder, the section through the knockdown punch being taken on line 16-16 of Figure 1'7,

Figure 17 is a bottom down punch,

Figure 18 is a perspective view, in a vertical position of the completed cathode sleeve, and,

Figure 19 is a side elevation of the cathode sleeve shown in Figure 18, assembled with a grid and associated elements.

plan view of the knock- In Figures 15 and 18 I haveshown a cathode sleeve 20, which is cylindrlcal for the purpose of illustration. The sleeve 20 has single-layer flanges 2| and 22, which overlain-are welded together and bent over or down upon the sleeve, providing a seam of two layers and which serves to stifien the sleeve. Tab sections 23 and 24 are formed integral with the sleeve, are in alignment with the flanges 2| and 22 and form in effect continuations of the same. The tab sections are also welded together. -Theflanges and tab sections have no interlocking engagement and are secured together solely by welding. The flanges 2i and 22 are arranged upon the outer surface of the sleeve and are transversely slit at 25, affording an outwardly projecting stop shoulder I 28, which is generally radial.

of the flanges and tab sections is .020" (20 thousandths of an inch). These dimensions may vary somewhat either way. Cathode sleeves are made having an internal diameter as small as .020" (20 thousandths of an inch). The dimenupon the recited to show the inherent difliculties encounner. As the metal ribbon is unwound from the spool it is transversely flat.

The step-by-step feed of the metal ribbon may be effected-by any suitable means, and I contemplate using a block having a. flat recess 3|.

Arranged above the block 30 is a top 32 rigidly secured thereto and this top has a vertical opening 33, to receive a friction pin 34, forced down by a spring When the spring acts upon the friction pin 34 this friction pin engages the ribbon 21 and holds it to the block 30 so that the ribbon will move with the block when the block moves forwardly. When the. block moves rearwardly, the intermediate portion of the spring 35 is elevated, relieving the tension from the friction pin 34, and the block may thenslide' rearwardly withrelation to the ribbon, which is then held against rearward movement. The spring 35 is attached to the. top 32 and any suitable means may be employed to operate the spring and any suitable means may be employed to reciprocate the block 30. The block 30 is moved forwardly on each cycle of operation for a distance equal to the combined length of the completed sleeve and tab sections.

The lower block 30 carries a forming roller 35, having a concave periphery whichfis channeled or V-shaped in cross-section and the roller 36 coacts with an upper forming roller 31, carried by the top 32. The roller 31 is convex and has a periphery which is V-shaped in cross-section, corresponding to the cavity of the roller'36 and adapted to enter the same. The low point 38 of the roller v36 is to one side of the center 99 of this roller, providing a face 40 longer than the face 4|. The high point 42 of the roller 31 is to one side of the center 39 providing a face 43 longer than the face 44. The upper roller 31 is provided adjacent to one end of this periphery with an annular groove 45, to receive an annular set of drawing studs 46, carried by the roller 35.

When the block 30 and associated elements are moved from the rear position, Figure 1, to the forward position, it will advance the ribbon 21, as explained. When the ribbon is thus advanced, the forward portion of the ribbon is clamped against rearward movement and the tension of the spring 95 is released from the pin 34 and the block 30 and associated elements are then moved rearwardly and returned to the rear position. The block 30 and the forming rollers 3| and 31 then travel rearwardly with relation to the then stationary ribbon 21,'and the peripheriesof the forming rollers 39 and 31 engaging with the ribbon 21 form or bend the same into a -V-shape, as shown. In this V-shape one side 41 is wider than the other side 48. At the same time, the drawing studs 46 produce a row of spaced raised portions 49 adjacent to one longitudinal edge of the ribbon. These raised portions or bumps 49 have their convex faces next to the upper face of the side 41, Figure 2. The

ribbon is formed or bent into the V-shapeand the raised portions 49 are formed when the block 30 and associated elements move rearwardly with respect to the ribbon. When the block 30 and associated elements move forwardly, they feed the ribbon forwardly, and that portion which is V-shaped is rendered thereby stiff so that it is fed forwardly by a pushing action, while that portion of the ribbon at the rear of the block is fed forwardly by a pulling action. If the forward portion of the ribbon were not stiffened by the V-shape, it would not be sufficiently stiff to be properly pushed forwardly.

When the V-shaped portion of the ribbon is pushed forwardly it is moved to a stamping position and is arranged within a V-shaped recess 50 of a stationary die 5|, having a vertical opening 52, to receive a punch 53, carried by a vertically reciprocatory head 54. The numeral 55 designates a stripper, having an opening 56 to receive the punch 53 and a groove 53 to receive the raised portions 49 and move downwardly by springs 51. The stripper 55 has its lower face v-shaped to conform to the shape of the recess 50. When the V-shaped portion of the ribbon 2'! is moved into the recess 50, the head 54 is shifted downwardly and the stripper 55 moves downwardly and clamps the V-s'haped portion of the ribbon within the recess 50, subsequent to which the punch 53 moves down below the stripper 55 and enters the opening 52 of the die and stamps out the opening 51. When the head 54 rises, the punch 53 moves upwardly with respect to the stripper 55 and the V-shaped portion of the ribbon will be separated from the punchby the stripper. When the head 54 is in the uppermost position both the stripper and punch are spaced from the V-shaped portion of the ribbon. When the stripper 55 is clamping the V-shaped portion of the ribbon in the recess 50, the ribbon is held against rearward movement, and during this time the block 30 and associated elements are shifted rearwardly. The formation of the opening 51 provides the tab sections 23 and 24, arranged adjacent to the longitudinal edges of the V-shapecl portion of the ribbon and extending longitudinally of such V-shaped portion beyond one end of the same.

When the block 30 and associated elements are again moved forwardly this V-shaped portion of the ribbon is advanced to the sleeve forming or bending position, and when the head 54 again moves downwardly, the cutter 50 is moved upwardly to sever the tab sections 23 and 24, at 59, whereby the leading V-shaped ribbon sec-tion is separated from the ribbon. This section is used to form the sleeve and tab of the cathode sleeve. Particular attention is called to the fact that the raised portions 49 extend throughout the entire length of the V-shaped portion and the entire length of the tab section 24. When the leading section is thus shifted to the bending position it is introduced into a V-shaped recess 60 of a vertically movable forming die 6|, then in the lowered position. The forming die also has a cylindrically curved recess 62, receiving the apex of the V-shaped section. The cylindrically curved recess 62 is preferably less than half of a cylinder whereby the sides 41 and 4B of the section, when further bent extend upwardly in a diverging relation. The center of the recess 62 is to one side of the longitudinal center 63 of the die 6|. The numeral 64 designates a horizontal mandrel or core which is cylindrically curved for coaction with the recess 62. The mandrel or core 64 is cylindrical except for an upper flat face 65, as

shown. The mandrel 64 is concentric with respect to the recess 62. During the forming of the sleeve, with the V-shaped strip within the recess 60, the mandrel 64 is held stationary above the die 6! and the die is first raised sufi'iciently to clamp the V-shaped section between the mandrel and the die and the die is then stopped before the mandrel 64 has reached its lowermost position within the recess 62 and the die 6| is held stationary. A knock-down die 66 is now moved downwardly into engagement with the top of the mandrel 64 and forces it to the lowermost position within the recess 62 and the mandrel 64 and the recess 62 now bend the section to provide a lower cylindrically curved portion 61 carrying the upstanding upwardly diverging sides 4! and 48. The side 41 extends above the side 48, by virtue of the off-center arrangement of the recess 62 and the mandrel 64 and the Wider side 41 carries the raised portions 49. After this operation, the knock-down die 66 is elevated and separated from the mandrel 64. Horizontal reciprocatory electrical resistance welding jaws 68 and 69 are moved inwardly and engage the upstanding sides 41 and 48 and complete the forming or bending of the same about the mandrel 64 and form the flanges 2| and 22. These jaws 68 and 69 are insulated from parts 6| and 64. The welding jaw 68 moves inwardly beyond the center 10 of the mandrel 64 while the welding jaw 69 moves inwardly and terminates short of this center, whereby the flanges 2| and 22 are arranged adjacent to one longitudinal edge of the flat face 65 of the mandrel 64. The welding jaws 68 and 69 have Vertically inclined welding faces H, which are preferably free from notches although notches may be used if desired. The welding jaws extend for the entire combined length of the sleeve and the tab sections.

As the welding. jaws 68 and 69 move inwardly they first bring the convex ends of the raised portions 49 of the flange 22 and tab section 24 into contact with the flange 2| and tab section 23, and since these raised portions are convex, the minimum area is afforded at the instant of contact between the raised portions and the flange and tab section, thereby producing the maximum resistance at the points of contact. As soon as the jaws move inwardly sufliciently to effect the contact, as described, a welding current is supplied to the welding jaws 63 and 69, and the raised portions 49 and the contacting portions of the flange and tab section are rendered plastic, and during this welding period the jaws 68 and 69 continue to move inwardly until the flanges and tab sections are brought into flrm contact and the raised portions or bumps are flattened out. The inward pressure of the welding jaws 68 and 69 follow through during the entire welding period so that there can be no flashing and the flanges and tab sections are brought into firm contact after the raised portions are flattened, and the current is cut off when the jaws still exert the inward pressure. I use an alternating current of low voltage and high amperage. Satisfactory results are obtained by using an alternating current having a voltage of approximately three (3) Volts and an amperage of approximately 2,000 amperes. During the welding period, the current stays on for only a short time, and I have found that satisfactory results are obtained by having the current turned on for one-half /2) cycle. The invention is not restricted to the precise voltage and amperage and time recited, as these may be varied. The welding jaws also weld the tab sections 23 and 24 together in the same manner as the sides 2! and 22. The tab sections 23 and 24 are in alignment with the flanges 2| and 22 and are disposed in the planes of the same. The flanges and tab sections are arranged exteriorly of the sleeve, are inclined and are generally radial with relation to the sleeve and are disposed upon one side of the center of the sleeve. The mandrel or core 64 extends for the entire length of the sleeve and tab section.

During the welding operation the die 6| and the mandrel B t remain stationary, and they remain stationary during the next step of bending down the welded flanges and tab sections. After the jaws 68 and 69 are moved to the open position, the knock-down die 66 is again operated. This knock-down die 56 extends throughout the entire length of the sleeve and tab. The knockdown die has a cylindrically curved recess 12, having its center in alignment with the center of the recess 62. The flanges 2i and 22 which are inclined are ofi-set with respect to the center of the sleeve and the center of the recess 12. It is thus apparent that when the knock-down die 66 again descends it will engage the Welded flanges 2i and 22 and the tab sections 23 and 24 and bend them down over the flattened portion of the sleeve, and this bending down will occur throughout the entire length of the sleeve and the tab except for a short portion which provides the upstanding stop shoulder 26. The shoulder 26 is provided by forming the knock-down die 66, Figure 16, with a transverse slot 73 having a width corresponding to the length of the shoulder 26. A supporting element or hook 'M extends into the slot 73 and is adapted to engage behind the shoulder 26, to prevent the same being bent down. The hook i supports the shoulder 26 and the edges of the slot 13 serve to out or shear the 0 flanges 2! and 22 at the lines 25. The hook elesuitable means.

ment never moves downwardly sufliciently to engage the mandrel or sleeve thereon but does move downwardly sufflciently to engage behind the shoulder 26. The hook may be operated by any I have shown a spring 75 to raise the hook and an adjustable screw 16 carried by the knock-down die 60 to depress the hook. When the die 86 is raised the space between the screw !5 and the hook M is such that the face of the recess 12 of the die 66 will engage the sleeve upon the mandrel 64 before the hook it has moved downwardly to engage such sleeve.

After the bending down operation the knockdown die is raised, the hook l4 rises and the 55 forming die 61 is lowered and the mandrel 66 is moved horizontally through a strip-per ll which strips the completed sleeve from the mandrel. This completes the cycle of operation of the method. The various instrumentalities employed in the practice of the method will be moved in properly timed order, and they may be moved manually or automatically.

The sleeve shown in Figure 18 is thereby produced, and the bent-down flanges 2i and 22 provide a seam of two layers, forming three layers with the adjacent part of the sleeve, and the shoulder 26 is at or in this bent-down seam. In Figure 19 I have shown the cathode sleeve 20 of Figure 18 assembled with a grid 18 and anode 1c, in a manner somewhat similar to the arrangement shown in Figure 4 of Patent 2,079,057. In Figure 19 the numeral designates an upper mica disk and 8! designates a lower mica disk, supported by posts 82. The sleeve 20 contains the usual resistance element or heater including lead-in wires 83 and the sleeve is coated at 84 with barium or strontium carbonate, corresponding to the coating I! of Patent 2,079,057. This coating when raised to the proper temperature becomes a good emitter of electrons. The tab 22 formed by the tab sections 23 and 24 may be bent slightly so that it can be attached or welded to one of the posts 49. The shoulder 23 rests upon the top of the disk 8!, and supports the sleeve, the ends of which are inserted within openings 85.

It is to be understood that the form of my invention herewith shown and described is to be taken as a. preferred example of the same and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, what I claim is:

l. The method of producing a cathode sleeve for a thermionic valve, comprising stamping an opening in one end of a metal strip to provide longitudinally extending tab sections formed integral with the strip near its longitudinal edges, bending the strip carrying the tab sections about its longitudinal axis, applying pressure to the outer sides of the strip near its longitudinal edges to complete the bending for forming a sleeve having laterally and outwardly extending flanges with the tab sections constituting continuations of the flanges, each flange and each tab section consisting of a single layer, and welding the flanges together and the tab sections together while maintaining each flange and each tab section in the single-layer condition.

2. The method of producing a cathode sleeve for a thermionic valve, comprising forming longitudinally extending single-layer tab sections integral with and upon one end of a strip of sheet metal adjacent to the longitudinal edges of the strip, bending the strip about its longitudinal axis to produce the sleeve and forming longitudinal single-layer flanges at the side edges of the sleeve, the tab sections constituting extensions of the flanges, and welding the flanges together and the tab sections together while maintaining each flange and each tab section in the single-layer condition.

3. The method of producing a cathode sleeve for a thermionic valve, comprising forming an opening in a metallic sheet for providing a body portion and spaced single-layer tab sections extending longitudinally beyond one end of the body portion, bending the body portion about its longitudinal axis for forming a sleeve and singlelayer longitudinal flanges projecting laterally of the sleeve, and welding the flanges together and the tab sections together while maintaining each flange and each tab section in the single-layer condition.

4. The method of producing a cathode sleeve for a thermionic valve, comprising forming an opening in a. metallic sheet to provide a body portion and spaced single-layer tab sections adjacent to the longitudinal edges of the body portion and extending beyond the end of the body portion, bending the body portion about its longitudinal axis for forming a sleeve and single-layer longitudinal flanges projecting laterally beyond the outer surface of the sleeve while causing the tab sections to substantially align with the flanges, bringing the flanges in opposed substantially parallel close relation while bringing the tab sections in opposed substantially parallel close relation, and welding the flanges together and the portion having longitudinal edges and longitudinally extending spaced single-layer tab .sections adjacent to the longitudinal edges, bending the body portion about its longitudinal axis for forming a sleeve and single-layer longitudinal flanges projecting laterally uponthe outer side of the sleeve, bringing the flanges in opposed close relation and bringing the tab sections in opposed close relation, and welding the flanges together and welding the tab sections together while maintaining each flange and each tab section in the single-layer condition. y

6. The method of producing a cathode sleeve for a thermionic valve, comprising forming an opening in a metallic sheet to provide a body portion andspaced single-layer tab sections extending beyond the end of the body portion, bending the body portion about its longitudinal axis for forming a sleeveand single-layer longitudinal flanges projecting laterally upon the outer surface of the sleeve, arranging the flanges in overlapping relation and welding them together and arranging the tab sections in overlapping relation and welding them together while maintain- ,mg each flange and each tab section in the singlelayer condition, and bending down a portion of the welded together flanges to lie in close relation upon the outer surface of the sleeve.

7. The method of producing a cathode sleeve for a thermionic valve, comprising forming an opening in a metallic sheet to provide a body portion and spaced single-layer tab sections extending beyond one end of the body portion, bending the body portion about its longitudinal axis for forming a sleeve and single-layer longitudinal flanges projecting laterally upon the outer surface of the sleeve, arranging the flanges in overlapping relation and the tab sectionsin overlapping relation, welding the flanges together and the tab sections together, bending down a portion of the welded flanges upon the outer surface of the sleeve, and forming a stop shoulder upon the flanges.

8. The method of producing a cathode sleeve for a thermionic valve, comprising stamping an opening in one end of a metal strip to provide longitudinally extending tab sections formed integral with the strip near its longitudinal edges,

.forming raised portions along one longitudinal edge and one tab section, bending the strip carrying the tab sections about its longitudinal axis andapplying pressure in an inward direction to the strip adjacent,to its longitudinal edges and the tab sections, for forming a sleeve having outwardly extending flanges, each flange and each tab section consisting of a. single layer, and welding the flanges together-and the tab sections to-.

gether while maintaining each flange and each tab section in the single-layer condition.

9. The method of producing a cathode sleeve for a thermionic valve, comprising forming longitudinaily extending tab sections integral with and upon one end 0! a. sheet metal strip adjacent to the longitudinal edges of the strip, forming a group of raised portions upon the strip whichgroup extends longitudinally of one longitudinal edge and one tab section, bending the strip about its longitudinal axis to produce the sleeve and forming longitudinal single-layer flanges, and

welding the flanges together and the tab sections together while maintaining each flange and each tab section in the single-layer condition. a 10. The method of producing a cathode sleeve for a thermionic valve, comprising forming a group of raised portions adjacent to and extending longitudinally of one longitudinal edge of an elongated strip, stamping an opening in one end of the strip to provide single-layer tab sections with the raised portions upon one tab section, bending the strip about its longitudinal axis into a sleeve having single-layer flanges at the longitudinal edges, and bringing the flanges and tab sections into close relation and welding the same together while maintaining the tab sections and the flanges in the single-layer condition and securing them together solely by the welding.

11. The method of producing a cathode sleeve for a thermionic valve, comprising bending a flat elongated metallic strip into a. V-shape and forming a group of raised portions adjacent to one longitudinal edge of the strip and extending longitudinally of the edge, formlngan opening in one end of the strip to provide longitudinal singlelayer tab sections with the raised portions extending longitudinally upon one tab section, bendingthe V-shaped strip about its longitudinal axis to form a sleeve to provide overlapping singlelayer portions and for causing the tab sections to overlap, and welding the overlapping portions and the overlapping tab sections together while maintaining the tab sections and the overlapping portions in the single-layer position and securing them together solely by the welding.

12. The method of producing a cathode sleeve for a thermionic valve, comprising forming an opening in a metal strip to provide longitudinally extending single-layer tab sections formed integral with the strip near its longitudinal edges, bending the strip about its lo'ngitudinalaxis for forming asleeve and generally radial outwardly extending single-layer flanges and inclining the flanges, welding the flanges together and the tab sections together while maintaining the flanges and tab sections in the single-layer condition and thereby securing the same together solely by the welding, and applying pressure to the inclined flanges in a direction toward the sleeve to benddown the inclined flanges.

13. The method of producing a cathode sleeve for a thermionic valve, comprisingiorming single layer tab sections integral with a. metal strip adjacent to the longitudinal edges of the metal strip, bending the strip about its longitudinal axis to produce the sleeve and forming longitudinal single-layer flanges at the side edges of the sleeve, the tab sections extending beyond the sleeve from points adjacent to the flanges, and welding the flanges together and the tab sections together while maintaining each flange and eachtab section in the single-layer condition.

HENRY masrmw.

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