US2538411A - Vacuum tube sealing mechanism - Google Patents

Description

Jan. 16, 1951 Filed Sept. 16, 1949 E. D. CARTER VACUUM TUBE SEALING MECHANISM 5 Sheets-Sheet 1 I I I l Jan. 16, 1951 Fiied Sept. 16, 1949 E. o. CARTER 2,538,411 vAcuuu was SEALING uscamrsu 5 Sheets-Sheet 2 Jan. 16, 1951 E. D. CARTER VACUUM TUBE SEALING IIECHANISII 5 Sheets-Sheet 3 Filed Sept. 16, 1949 Jan. 16, 1951 E. o. CARTER VACUUM TUBE SEALING MECHANISM 5 Sheets-Sheet 4 Filed Sept. 16. 1949 Jan. 16, 1951 E. D. CARTER 2,533,411

VACUUM TUBE SEALING MECHANISM Filed Sept. 16, 1949 5 Sheets-Sheet 5 Patented Jan. 16, 1951 2,538,411 VACUUM TUBE SEALING MECHANISM Elmer 1). Carter,

notation of Illinois Chicago, llL, lllimr to National Video Corporation,

Chicago, Ill, a cor- Applicatlon September 18, 1949, Serial No. 110,.

(Cl. 31H!) 14 Claims.

The present invention relates to improvements in apparatus for exhausting and sealing vacuum has In the manufacture of certain classes of vacuum tubes, particularly cathode ray picture screen tubes and similar glass envelopes which assume large and unwieldy proportions, there are presented divers handling problems during assembly line progression having particular reference to the successive operations of bombardment heating drive ofl of surface absorption and oxidation, air exhaustion, and thereafter sealing-off to effect a preservation of the established conditions within the tube. These operations may be performed at fixed stations or in a continuously moving assembly line arrangement, the principal object to be accomplished being the utilization of emcient methods in sealing-oil the tubes during the optimum exhaust and heating conditions.

In the performance of the aforedescribed operations, the tubes are supported on cradles or saddles in a neck-down position with their large or flared sections uppermost. While the tubes are being heated, they are preferably confined in individual Jackets. The stem portions of the tubes through which the gas exhaustion is effected are connected through airtight coupling with mechanical and diilusion pump systems. When the mechanical pump which is first operated reaches a predetermined degree 01' exhaustion, the diffusion or aspirator attachment is initiated into operation and through its performance residual gas elements are conditioned so as to be more eifectively removed by the mechanical exhaustion.

When the optimum condition of exhaustion is attained, the tube being at this time also maintained at a high heat level, it is most appropriate to seal-oil and preserve the vacuum condition without further delay.

Since previous seal-oil operations have contemplated the mechanical lifting away of the tube from its stem. it has been the practice to wait until the tube has cooled substantially below the 350 Cent. temperature in order to facilitate handling. With the present invention, however. the seal-oil. operation is consummated by all mechanical apparatus and is permitted therefore to be performed during the optimum of conditions.

' In addition to the foregoing considerations, the prompt seal-oil operation is a contributing factor for more eiIiciently utilizing the exhaust apparatus and making it available for reloading so much sooner than where cool-oil time is permitted before the tube is sealed. This efllcieney is manifest in several respects not the least important of which is the investment in exhaust apparatus for a given quantity production line.

In accordance with the present invention, alternative methods have been devised for accomplishing this operation and for thereafter separating the tube from the ofl'al stem.

Since the tube is of considerable weight and is essentially an unwieldy device to be handled even when cold, it has been found an onerous and diffleult task to be performed by a single attendant in severing the seal-oil tube and thereafter separating the picture bottle from it. In accordance with the present invention, therefore. it is sought to obviate these diiliculties by the provision of a unique type or pump support structure and clamping chuck whereby following the seal-oi! operation the tube may be permitted to remain in its supporting cradle and, instead. the oil'al stem drawn away by the manipulation of a favorably baianced pump and chuck supporting structure that may be actuated by means oi a simple oil'set rod.

A principal object of the present invention, therefore, is one of providing a novel type of vacu um tube exhausting apparatus in which the exhausting pump and its associated elements are rendered mobile so as to be quickly and conveniently drawn away from the tube.

Another object of the present invention is to provide a counterpoised pump and exhaust structure for vacuum tube sealing apparatus which may be manipulated by the administration of but small physical effort and which may be so counterbalanced as to draw way from the seal-oil stub at precisely the correct acceleration which will attenuate the stem so as to properly produce the seal-01!.

Further and additional objects of the present invention are such as will be evident during the course of the following detailed description and such as will be better understood during an explanation of the operation as will follow hereinafter. Accordingly, attention is now directed to the accompanying drawings and to the following detailed specification in both of which like reference numerals designate corresponding parts throughout, and in which:

Fig. l is a side elevational view of a battery frame structure in which a plurality of heat treating air exhausting and sealing-01f apparatuses may be incorporated in close proximity to one another. In this figure various stations are illustrated in ditferent positions.

Fig. 2 is an enlarged transverse sectional view of a portion 0! the apparatus illustrated in Fig. 1

observed from a real-most vantage point and feaurlng the exhaustin pump apparatus and its related subtable structure;

Fig. 3 is an enlarged detail sectional view of the apparatus which is located adiacent the seal-off tube including the coupling chuck, its backing gland and the bombardment coil in fragmentary section;

Fig. 4 is an enlarged transverse sectional detail view taken approximately on line H of Fig. 3;

Fig. 5 is an enlarged fragmentary sectional view taken approximately on line 5-4 of Fig. 3;

Figs. 6. 7, 8 and 9 are a succession of enlarged detailed elevational views of the seal-off operation in progressive stages of advancement;

Fig. 10 is a fragmentary detail view of the counterbalancing structure featuring the manner of securing the counterpoised springs to the floating pump support framework;

Fig. 11 is an enlarged transverse sectional view of the improved apparatus featured in Figs. 2 and 10; and

Fig. 12 is a transverse sectional view taken approximately on line "-42 of Fig. 2.

In the drawings. the reference numeral ii designates an overhead channel framework within which are journalled a plurality of sheave wheels I! to accommodate the overhead svstems including the furnace Jackets l8 and their counterbalancing weights II.

The furnace jackets is. see also Fig. 2, are essentially cylindrical enclosures of double thicknesses of metal between which an intervening space is filled with heat insulating material It. The Jackets are confined to parallel vertical movement by having guide projections is which straddle flange or guide elements H at convenient locations of the adjacent framework.

A plurality of vertical support channels i8 riveted to the cross channel members is give support to the overhead beams ll. while at table level there are provided skirting angle irons as at Ii upon which there rests a thickness of fireresistant table covering such as the asbestos sheet 22. The upright channels I! extend down to the floor where they rest on transverse channel members 28 preferably on cushioning blocks 2|. By engaging the handles 25 on each of the furnace jackets II they may be raised and lowered to assume the various positions illustrated in Fig. 1.

when the jackets are in their raised positions. there may be instal ed upon or removed from the supporting yokes 28 the picture tube bottles 21 which theretofore have already undergone various stages of manufacturing assembly. including the installation of the gun structure into the neck 28 of the tube and thereafter the burningof! of the skirting flange as a bond is established between the neck portion I! of the tube and the glass end wafer through which the terminal wires of the gun element protrude.

The tubes are proportioned so that they will rest with their converging or funnel shaped intermediate sections seated between the opposed arcuate segments 29 of the yoke members 25, which segments may be encased with a heat resistant and yet resilient material. While in this position. the tubes are practically centered and held at such elevation as to permit a significant length of the sealing-off stern II to intervene between the chuck nut I2 and the wafer generally designated by the reference numeral 33. which is the region whereat the neck II has been cut off by heat bonding with the wafer element ll, see particularly Fig. 3.

In accordance with an adaptation of packing gland illustrated in Fig. 3, the chuck nut 32 is drawn down upon a nipple section at. and by so doing. there is applied a compression onto the resilient gland washer 36. This establishes an airtight seal between the internal chamber 3! of the water cooled sleeve 88 and the sealing-off stem 8| which is now to become separated by 10- calized heating and attenuation treatment after a manner of practice generally resembling the heretofore known procedure.

It is to be understood that all the operations which are requisite to be performed before the sealing-oil are consummated in the usual manner and that it is presumed that the next step of procedure is to effect the disjunction of the stem II in the sealing-0d operation to permanently enclose the evacuated space within the tube proper. The space within the tube now communicates through the stem Ii with the exhaust conduit 39 which passes through a diffusion pump generally designated ll. Thereafter this communication continues out of the diffusion pump through a rigid tube 42. thence a flexible connecting tube 43 with the exhaust orifice of a mechanical pump mechanism generally indicated 44 driven by an electric motor ll.

In Fig. 2 it will be readily observed that the motor and mechanical pump are a combined unit carried by a base 45 which is rigid in the foundation structure 41. Through the flexible linkage tube It the exhaust communication is extended through the floating aspirator or diffusion pump I l. the supporting structure of which will now be explained.

Pump ll consists essentially of a vapor generating base structure 49 which is made effective by heating, and a self-contained electric heating element serviced through the wires H. The pump and all of its super-structure is carried upon a strap element or ball 52 and confined against rotation by having a pair of straddling guide rollers Iii at each side between which there passes an upstanding uide element 54 or 55. On the lower surface of the supporting strap 5! there is secured a downwardly extending rod 88 which passes through an opening in the flange l1 and cross-strap l8 and to this fulcrum rod N there may be secured as by welding at 59 the manipulator rod 60 which extends sidewardly and then upwardly to be capped by a convenient knob 6| suitable for manipulation. The raising and lowering of the assembly which includes the diffusion pump. the chuck nut and its cooling Jacket 38, as well as the other members carried upon the base 92. is an operation which is carefully guided so as to maintain concentric alignment with the stem If. This guidance is safeguarded not only by the rollers 83 and their guide rods 54 and 55, but also there are provided three equally spaced guide rollers Ill around the outermost sleeve 38 iournaled on horizontal axes whereby the upper end of the described assembly is securely confined against any effects or forces tending towards distortion.

It will be observed that the downwardly extending rod 56 is loosely fitted after the manner of a fulcrum seating in the center of a crossbeam 62 at whose ends there are connected the lower extremities 63 of a pair of counterpoise springs. preferably of the coil type whose upper extremities 64 are carried by the adjustment eyebolts Ii! through which tension may be regulated. The

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physical characteristics of the oounterbalancing springs are calculated to be marginally inadequate to sustain the full weight ofthe aspirator pumps and the additional superstructure which is balanced on the fulcrum rods II and which is carried by the cross-member If on the indicated arrangement of weight distribution between the two springs. In this way it becomes necessary during the attachment of the chuck nut and gland 81-80 to the stem 8! for an-operatorto first lift the knob CI to its full height, which is the condition shown in Fig. 2. so that the nut 12 maybedisposedtoengmthestemli atashigh a point as possible leaving the maximum dimension to be utilized in the attenuation when the glass of the stem becomes softened.

The heat which is applied to the stem requires to have suilicient calorific intensity to raise the temperature of the glass to its flowing point in order to achieve the condition which has been portrayed by the successive stages of Figs. 6 to 9, inclusive. Under one mode of operation a manually held gas burner jet with two forked burner elements opposing each other has been utilized in'order to first temper and then concentrate in the attainments of localized heating collapse in the wall of the stem 8|. illustrated in Fig. 9 in which the two frames address one another eiiecting a maximum heat cone at a common vortex or at slightly spaced ilame cone centers. In carrying on the operation with the gas flame method of treatment, close attendance is usually a prerequisite since the socalled tempering treatment requires that the adlacent areas to the collapse zone of the stem be moderately heat conditioned in order to avoid setting up severe stresses, such as are consequent from the characteristic poor heat conductivity of glass.

On the other hand, it is proposed that as an alternative treatment a heat induction coil of the high frequency p or of any other radial heat type, be employed in which the tempering operation of a battery of stations may be regulated under a single supervision and brought up to collapse temperatures gradually enough to avoid shock stresses. This type of heating coil designated ii maybe supported in any suitable manner from adjacent conducting buses, or it may be made to perform as a disappearing cell after the manner of the bombardment helix I! which will be discussed later.

After the temperature of the glass has been raised to the softening point, an initial manifestation of collapse, such as that shown in Fig. 7, will occur due in part to the attenuation of the tube by reason of the preponderance of weight which is designed in accordance with the characteristic of the balancing springs and partially to the air pressure differences between the outer and inner spaces.

When the attenuation has reached its maximum effects, such as that illustrated in Figs. 8 and 9, an intense localised heat device such as the gas frame apparatus is may be employed to effect the final parting of the two sections of the tube. Thereafter, the operator may re-establish momentary contact between the two disjoined and attenuated portions of the tube II to effect a closure of the remaining fissure after the glass tubing has been parted by raising the control knob Ii.

Attention will now be given to an additional operation which is performed earlier in sequence to the aforedescribed cut-off operation, but

This type of burner is which concerns an adiunct apparatus designed to make the procedure more expeditious to perform and more precise in its results. The socaiied gun structure generally designated Ii in Fig. 3 consists of a metallic assembly, including the cathode element as well as one or more anodio accelerators in concentric alignment. According to conventional practice, with this gun assembly there is also made accessory an expendable oxidation cartridge known as a "getter" which is designed to be ilred for the purpose of removing gases which are given off particularly by the oxide coated cathode when that element becomes heated during the normal operation of the tube.

Before the sealing-oil operation, as above described, is completed, it is considered preferred practice to raise the temperature of the entire gun structure to a measured maximum de ree such that there will be driven off from all metallic surfaces foreign adherence and oxidation, but this so-calied bombarding temperature must be carefully regulated so that it does not approach the degree of intensity requisite to firing the aforede'scribed getter. Towards these ends there is provided the already mentioned induction heating coil or helix II, the diameter of whose convolutions are so proportioned that they may encompass the neck 28 of the tube, while yet be small enough to be received within the dimensions afforded by an opening I! circumscribed with an upstanding sleeve 83.

Since the so-called bombarding operations are practices which require for their successful com" summation merely well engineered electrical regulation, a series of such bombardment operations can be accurately and effectively carried on simultaneously through the efforts of a single attendant. With this in mind, the table structure 22 has been so designed as to afford the disappearing recess 8! through which the coil I! may be made to recede and the several coils for batteries of such installations may receive their high frequency power communication in parallel or over individual cables ll carried by a common channel member which is capable of being lifted in parallelism, safeguarded by the guide rode it and the guide sleeves 81 through which they pass.

The making of the induction coils if to be so manifestly convenient in their simultaneous function as well as in their simultaneous withdrawal from the fields in which subsequent operations are intended to be consummated is an achievement which has been observed to materially reduce spoilage hazards as well as to maintain consistency under high production factory processes.

While the present invention has been explained and described with reference to certain arbitrary chosen embodiments and exemplary illustrations, it will be understood, nevertheless, that numerous modifications may be incorporated without departing from the essential spirit or scope thereof. Accordingly, it is intended not to be limited by the particulars of the accompanying drawings nor by the language chosen in the foregoing description, except as indicated in the hereunto appended claims.

The invention claimed is:

1. In a tube exhausting and sealing apparatus, a fixture for supporting a tube to be evacuated in vertical position with its exhaust communieating stem downward, a carriage supporting a system of exhaust pumps and a coupling chuck in assasu" concentric alignment with the stem of said tube, roller guides for confining said carriage and its system of pumps to vertical movement in axial alignment with said tube, counterpoise elements for supporting the weight of said carriage and its pumps, a manual lift implement for raising and,

lowering said carriage through a limited range of movements, and a heating element encircling said exhausting stem for raising the temperature oi said stem thereat to the melting point after said tube has been exhausted or its air content by said system of pumps.

2. A production line tube exhausting and seal ing apparatus comprising, a fixture for supporting a tube in vertical stem-down position, a system of exhaust pumps carried by a floating carriage in concentric alignment with the stem of said tube. a coupling chuck communicating with said system of pumps in axial alignment and said stem, guides for confining said carriage and its system of pumps in vertical movement, coil springs for supporting the weight of said carriage and its pumps, a manipulator for raising and lowering said carriage and its carried pumps, and a heating element disposable at a horizontal level transverse of said exhausting stem for thereat raising the temperature of said stem to the melting point, whereby the preponderance of weight of said carriage and pumps is utilized to alternate said stem at its level of melting point.

3. In a tube exhausting and sealing apparatus, a supporting fixture for maintaining a picture tube having a neck portion in stem-down position, apparatus to evacuate the air content of said tube while in this position, a cylindrical enclosure Jacket movable vertically between tube covering and tube exposure positions, a platform at a horizontal table level having a well portion in concentric alignment with the stem of the tube, a heat radial helix of a diameter to encircle the neck portion of a tube and to be recedable into said well portion of said platform, and a second heat radial helix of a diameter adapted to encircle the stem of the tube, said first mentioned helix being adaptable to raise the temperature within the neck of the tube to a sumcient degree to efi'ect heat bombardment of the contents within said tube neck portion and said second helix being electrically stimulated to raise the temperature of the stem p rtion of said tube to its melting point.

4. In a picture tube exhausting and sealing apparatus, a support for maintaining a picture tube in upright position with its exhaust stem downward, a floating assembly including an aspirator. pump, and a coupling chuck in axial alignment with the stem of said picture tube resting in said support, spring means counterbalancing the weight of said floating assembly, and a manipulator integrally associated with said assembly and extending upwardly in a vertical direction offset from the axial center of said tube and chuck alignment, for raising and lowering said assembly towards and away from said tube stem.

5. In a tube exhausting and sealing apparatus, a supporting fixture for nesting a picture tube in stem-down position, a horizontal platform at table level beneath the stem of said tube, having a well portion in concentric alignment with the tube, a bombardment coil heater adapted to encircle the neck portion of a tube and to recede into said well portion of said platform, and a radiant heater of a diameter adapted to encircle the stem of a tube, said bombardment coil heater being to raise the temperature within the neck of the tube to a suiilcient degree to eil'ect molecular dispersion of surface absorbed gases from mechanism within the tube and said radiant heater being stimulated to raise the temperature of the stem portion of said tube to its softening point.

6. In combination, a support for maintaining picture tubes in upright position with the exhausting stems thereof downward in vertical alignment, a floating carriage assembly including a system of exhaust apparatus and a couplin chuck in axial alignment with the stem of a picture tube resting in said support, spring means counterbalancing the weight of said carriage assembly, means for raising and lowering said carrlage assembly towards and away from said tube stems, and a counterbalance for a portion of the weight of said carriage assembly so that said assembly will be permitted to descend under gravitation of a portion only of its weight when the exhaust stem to which it is coupled at said chuck becomes softened.

7. In a vacuum tube exhausting apparatus, means for holding a tube envelope to be evacuated in vertical alignment with its exhaust and seal-oil stem downward, a platform at table level having a well aperture in axial alignment with the stem of the tube, a system of exhaust pumps communicating with a chuck in vertical axial alignment with said stem and carried by a floating support, means for guiding said support in vertical parallel movement, a manipulator integrally associated with said support and extending sidewardly and upwardly through said platform, tension adjustable counterbalancing elements for sustaining a portion of the weight of said support and its carried elements, and an electrically controlled heater encircling to the stem of said tube between said chuck and the neck of said tube for raising the temperature of said stem to its softening point whereby the preponderance of the weight of said support and its elements will attenuate said stem as its melting point is approached.

8. An assembly line machine comprising, a table level platform, a plurality of supports on said platform for holding picture tube bottles stem-down for gas evacuation, said platform having well openings in axial alignment with the stems of said bottles when held on said supports, a plurality of radiant heating coils of a diameter which will marginally encompass the necks of picture tubes and yet be submersible in said platform well openings, and a rack traversing a plurality of said supports having electrical connections with and affording physical support for said plurality of radiant heating coils so that pluralities of picture tubes may be thereby heat treated concurrently.

9. In an apparatus for exhausting vacuum tubes the combination including, a fixture for supporting a vacuum tube in a position with its exhaust stem downward, an exhaust pump assembly for extracting the gas content of a tube thus supported, comprising a carriage supported on springs and movable through a limited distance vertically towards and away from said tube, guide rollers for confining said assembly to vertical parallel movement, and a manipulator for raising and lowering said assembly in consort with or in opposition to the eflect of its springs.

10. In an apparatus for conditioning and exhausting vacuum tubes the combination including, a saddle for supporting a vacuum tube in a vertical position with their exhaust stems downward, an exhaust pump assembly comprising mechanical and aspirator devices for extracting the gaseous content of a tube thus supported, a central fulcrum projection extending downwardly from said assembly, a balancing beam for supporting said fulcrum projection, spring means at opposite ends of asid balancing beam having a distended lift tension approximating but not surpassing the weight of said beam fulcrum rod and said exhaust pump assembly at predetermined level, guide rollers for confining said assembly to vertical parallel movement, a manipulator including a handle for raising and lowering said assembly in consort with or in opposition to the effect of said spring means, and limit devices for determining the movement in a vertical direction of said assembly.

11. In a vacuum tube sealing machine, a fixture for maintaining a vacuum tube envelope in a vertical position with its exhaust communication port directed downward, a carriage supporting a coupling element for connection with said port portion and a system of exhaust pump elements confined in guide apparatus below said fixture so as to be movable in a vertical direction toward and away from a tube port of a tube restin in said fixture, weight counter-balancing means for sustaining a portion of the weight of said carriage and its supported elements, and a heating implement for softening the communication port portion of the tube whereby the preponderance of weight of said carriage and its elements may function to attenuate said port portion.

12. A production line machine for treating cathode ray picture tubes which comprises, a supporting cradle for holding a picture tube envelope in neck-down position, a system 01' exhaust devices for coupling to an exhaust tube extending from the neck of said picture tube. a heat implement for softening the exhaust tube, and apparatus for separating said supporting cradle from said exhaust devices when said exhausting tube has reached its softening temperature.

13. A method of manufacturing vacuum tubes of cathode ray picture screen magnitudes which comprises supporting a tube envelope which is in readiness for exhausting and sealing with its exhausting stem downward, supporting an evacuating and exhausting system in a vertically movable confinement space beneath the envelope communicative with said st m, counterpoising the weight of said evacuating and exhausting system to resolve a marginal preponderance to said system, heating the exhausting stem to melting point after the envelope gases have been exhausted and evacuated, and structure-sealing said stem by the attenuation effect produced by the descent of said system weight preponderance.

14. A method of structure-sealing glass stem vacuum tube envelopes which comprises the steps of supporting a horizontal alignment of vacuum tube envelopes with their glass tabulation stems downward at a gas elimination station of an assembly line, connecting to each stem a gas evacuating system of apparatus which is confined for limited vertical movement and whose gross weight is partially counterpoised, heating an intermediate portion of each stem until it achieves melting temperature, and collapsing said stem portion under evacuation pressure as the weight preponderance of the system attenuated said portion to sealing structure.

EIMER D. CARTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,219,891 Geiger et a1. Oct. 29, 1940 2,324,559 Cooke A July 20, 1943 2,398,340 Wilder Apr. 9, 1946

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