US2662345A

US2662345A - Apparatus and method for joining glass tubulations to glass bulbs

Info

Publication number: US2662345A
Application number: US212399A
Authority: US
Inventors: John V Ruggiero
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1951-02-23
Filing date: 1951-02-23
Publication date: 1953-12-15
Anticipated expiration: 1970-12-15

Description

Dec. 15, 1953 J v RUGGIERO 2,662,345

APPARATUS AND METHOD FOR JOINING GLASS TUBULATIONS TO GLASS BULBS Filed Feb. 25, 1951 INVENTOR .Jm-mY. RUEEIERB BY WM ATTORNEY Patented Dec. 15, 1953 UNITED STATES PATENT OFFICE APPARATUS AND METHOD FOR JOINING GLASS TUBULATIONS TO GLASS BULBS John V. Ruggiero, Jersey City, N. J., assignor to Radio Corporation of America, a corporation of Delaware 11 Claims.

The present invention relates to an apparatus and method for processing glass parts to form an assembly including a glass bulb and'a glass tubulation sealed to the bulb and communicating with the interior thereof for evacu-. ating the bulb. More particularly, the invention concerns an apparatus and method for properly orienting the tubulation with respect to the bulb and for urging the tubulation towards the bulb when the parts are joined to form the assembly.

One type of electron tube includes an envelope closed at one end by a stem through which leadins extend. The envelope is evacuated through an exhaust tubulation sealed to the end of the envelope remote from the stem. After the envelope is evacuated the exhaust tubulation is pinched off to seal the envelope.

During the manufacture of electron tubes of this type, it is advantageous to first form subassemblies of the parts making up the tubes, and subsequently to appropriately arrange and fix the sub-assemblies to form completed tubes. One sub-assembly for the type of electron tube under discussion comprises a tubular glass bulb open at one end and closed at the other and having sealed to it at its closed end an exhaust tubulation of relatively small diameter. The sub-assembly referred to is formed by positioning a glass bulb and exhaust tubulation in coaxial relation, heating the closed end of the bulb to soften the glass thereof, and urging the adjacent end of the tubulation against the softened closed end of the bulb. This causes the glass at said adjacent end of the tubulation to fuse with the softened glass of the bulb. While the glass at the closed end of the bulb is still soft, a relatively sharp flame is played thereon at a portion thereof in registry with the passageway through the tubulation and directed from the open end of the bulb to provide an opening in said closed end communicating with said passageway. An air jet at this time is usually directed into the tubulation from the end thereof remote from the bulb to aid formation of the opening referred to.

The steps referred to for forming the subassembly under consideration are usually carried out by a turret type machine having a plurality of heads for receiving and supporting glass bulbs and exhaust tubulations in coaxial relation.

One diillculty associated with this type of machine is involved in providing the necessary means for urging one end of the tubulation against the softened glass at the closed end of the bulb to which the tubulation is to be sealed. This difficulty is aggravated by the fact that it is impractical to cut exhaust tubulations exactly to the same length. Thus the urging means referred to requires automatic compensation to assure proper engagement between bulbs and tubulations during the sealing operation. Such automatic compensation has heretofore assumed complicated mechanical forms requiring clutches having automatic release features to avoid application of excessive force to the exhaust tubulation. Such clutches frequently go out of order and therefore require constant operator supervision.

Another difficulty is presented as a result of a partial collapse of the bulb when in the softened state. Thus, even though a tubulation were fed. so as to be initially in abutment with the closed end of the bulb, the partial collapse referred to will cause some displacement of the bulb from the tubulation.

The apparatus and method of the invention overcome these difficulties by supporting the exhaust tubulation in a readily releasable manner and relying on the weight of the tubulation to provide the necessary force for urging the tubulation into the softened glass of the bulb. The apparatus includes a tubulation gripper having two relatively movable parts for normally supporting the tubulation against movement with respect to the bulb. One of the movable parts is provided with a vane-like surface and responds in movement with respect to the other part when a jet of air is directed against the vane-like surface. This movement causes the gripper to release the tubulation so that it is free to drop -into abutment with the softened glass at the closed end of the bulb.

An important object of the invention is to provide an improved method and apparatus for joining parts capable of assuming a plastic form.

A further object is to provide an improved method and apparatus for joining a glass exhaust tubulation to a glass bulb to form a subassembly for an electron tube.

Another object is to effect a seal between glass parts, wherein the weight of one of the parts provides the required force for urging the parts together during a sealing operation.

A further object is to provide an improved apparatus for supporting glass parts to be joined in a seal in predetermined space relation and having means for releasing the support of one of the parts to cause said parts to be in abutment relation.

. vide a Sub-assembly for an electron tube.

Another object is to provide an apparatus for sealing a glass exhaust tubulation to a glass bulb for an electron tube, having means for supporting the tubulation including a vane-like member on said means responsive to an air jet for releasing the tubulation.

Further objects and advantages of the invention will appear from a consideration of the following specification taken in connection with the appended drawing in which Figure 1 is an elevation partly in section along the line II of Figure 3, of an apparatus including the invention; 7

Figure 2 is a transverse view along the line 2-2 of Figure 1 and shows the gripper of the apparatus for releasingly supporting an exhaust tubulation to be sealed to a glass bulb;

Figure 3 is a transverse view along the line 3--3 of Figure 1 and shows the bulb supporting means of the apparatus; and

Figure 4 is a fragmentary elevation of the apparatus shown in Figure 1, and shows the tubulation gripper in position for releasing the tubulation.

Referring now in more detail to the drawing, there is shown in Figure 1 a head of a turret type machine for sealing an exhaust tubulation II], which may be of glass, to a glass bulb II, to pro- The head includes a bulb holding means and a tubulation holding means.

The bulb holding means The bulb holding means comprises a sleeve I2 having a central bore for receiving a bulb II. The head also includes a sleeve I3 having a flange I3a fixed to sleeve I2, and a central bore in registry with the bore in sleeve I2. To the lower end of sleeve I3 is fixed a spur gear I4, also having a central bore in registry with the bores in sleeves I2, I3. Sleeve I2 is provided with a plurality of slots I5, I6, I! shown in Figure 3, radially extending from the central bore in the sleeve. In each of the slots referred to is disposed a bulb engaging member I8 having a bulbengaging edge I9, and extended

side portions

20, 2| adapted to be received snugly in depressions in the side walls of the slots I7, and on which the member is adapted to pivot. Adjacent the, lower end of each of the members I8 is a pin 22 connected to one end of a spring 23. The other end of the spring is attached to a pin 24 fixed to the flange i3a. A stationary burner 25 is adapted to play a flame on the top portion of bulb II to which tubulation I is to be joined.

The bulb supporting assembly comprising the sleeves I2, I3 is rotatable in a recess or bore 26 provided in turret 21 adjacent its periphery. To impart rotation to the assembly a spur gear 28 is provided, in meshed relation with spur gear I4. Spur gear 28 is fixed to shaft 29 for rotation therewith. On the lower end of shaft 29 is fixed a sprocket wheel 30 adapted to engage sprocket chain 3I. The sprocket chain is connected to a prime mover, not shown, for rotating shaft 29 and spur gear 28. The rotation referred to is desirable for evenly distributing the flame from burner 25 on the bulb held by the assembly referred to.

Mounted adjacent the upper end of shaft 29 for rotation therewith is a cam 32, the function of which will become apparent as the description proceeds,

The tubulation holding means The means for supporting the exhaust tubulation In, includes a standard 33 fixed to sleeve I2 and having an arm 34 fixed at one end to the upper portion of standard 33 as viewed in Figure 1. The other end of the arm 34 is provided with a V-shaped slot 35 for receiving the exhaust tubulation I0. Pivotally mounted on the arm 34 is a flat vane-like arm 36 having

legs

37, 38 engaging pin 39 extending through arm 34, for pivotal movement thereon in a vertical plane as shown in Figures 1 and 4. Arm 36 is provided with a sharp edge 40 shown in Figure 2, which in combination with the V-slot 35 in arm 34, serves to support the tubulation I0 by frictionally engaging t ree. ides t The bottom of the V-shaped slot 35 in arm 34 extends across the arm 34 in a straight line as shown at 4| in Figure 1. Thus, a portion of tubulation ID of appreciable length is engaged by the walls of the slot referred to. The arm 36 is mounted on arm 34 in such a mannerthat the edge 40 thereof which is relatively sharp, engages a smaller portion of the tubulation than is engaged by the walls of slot 35. This smaller portion is intermediate the ends of the portion of the tubulation engaged by the slot referred to for a purpose to be described. The edge 40 is disposed adjacent the lower surface of arm 36 as viewed in Figure 1, to permit release of the tubulation II] in an advantageous manner to be described, when the arm referred to is rotated counterclockwise, and to frictionally engage the tubulation during normal rest position of the arm.

For rotating the arm 36 in a counterclockwise direction means are provided comprising a conduit 42 connected to an appropriate source, not shown, of air under pressure, a conduit 43, terminating in a nozzle 44 and a valve 45 for selectively controlling air flow in conduit 43. The valve 45 is provided with a valve stem 46 urged outwardly from the valve by spring 41 to close the valve. The free end of stem 46 engages cam 32 and follows its surface.

Operation of the apparatus During operation of the apparatus the turret 21 is caused to rotate intermittently by means, not shown, through a plurality of Processing stations. The initial stations include means, not shown, for feeding the bulb II upwardly from the lower end of the bores in spur gear I4 and sleeves I2, I3, a predetermined distance. Dur ing the feeding operation referred to the bulb I I spreads the bulb engaging members I8 against the tension of springs 23. When the feeding operation terminates, the members I8 are urged against the sides of the bulb to effectively restrain it from movement with respect to the sleeves I2, I3. At a succeeding station a tubulation It! is fed to the tubulation gripper or support member comprising the

arms

34, 36. During this operation, the arm 36 is rotated counterclockwise as viewed in Figure 1 through a limited arc to enlarge the passageway provided by the V-slot in arm 34 and the edge 40 of arm 36 to permit receipt thereby of a tubulation I0. The duration of the counterclockwise movement referred to is short enough to no more than barely permit the lower end of thetubulation to reach the upper dome portion of the bulb I I. This is for the reason that the impact resulting from an unrestrained dropping of the tubulation on the bulb,

might crack or otherwise damage the tubulation and/or the bulb.

At a further station, the dome portion of the bulb is heated as by a flame to initiate fusion of the glass at this portion. At this station the tubulation is fully supported by the

gripper

34, 36.

At a further advanced station as shown in Figure 1, the dome of the bulb H is rendered sufficiently plastic for sealing to the lower end of the tubulation [6. To accomplish the seal, it is necessary that the tubulation be urged downwardly. These are several reasons for this requirement. One resides in the fact that tubulations are characterized by appreciable tolerances as to length. It is impractical to cut the tubulations to exactly the same length. Therefore, during the operation of feeding the tubulation to the apparatus, shorter ones of the tubulations may be appreciably spaced from the bulb H, as shown in Figure l. A further reason for the step of urging the tubulation downwardly is that a softening of the dome of the bulb weakens it so that to some extent it loses its ability to maintain its shape. This results in some, although slight, inward collapse of the dome. Therefore, even though a precisely cut tubulation were used that initially abutted against the dome during the feeding operation, the slight collapse of the dome, would displace it from the tubulation.

Therefore, at this further advanced station shown in Figure 1, rotation of the bulb by the sleeves l2, l3, spur gears Hi, 28 and chain St, for uniform application of the flame to the dome of the bulb, also results in rotation of cam 32. Such rotation of cam 32 causes the valve stem 45 to be successively moved in and out resulting in successively opening and closing the valve 45. The opening and closing of valve 45 causes an air jet to be intermittently directed by nozzle 45 to the underside of vane-like arm 36. The force of the air jet causes the arm 36 to rotate counterclockwise to a sufficient degree to intermittently release the tubulation Ill.

The intermittent release of the tubulation H3 causes it to abut against the softened dome of the bulb l l. The force of the abutment is determined solely by the weight of the tubulation Ill. The abutment relation is attained as a result of a downward drop of the tubulation. This downward drop is rectilinear as a consequence of the structure of the tubulation-engaging surfaces of the gripper arms 34, 3E. The structure of the V shaped end of arm 34 permits engagement with an appreciable longitudinal portion of the tubulation. This aids in guiding the downward drop of the tubulation in a straight line. The relatively sharp edge fill of arm 36 engages an opposite and relatively small part of the longitudinal portion referred to. The forces of the V shaped slot and the sharp edge referred to are therefore applied in such a manner as to support the tubulation at right angles with respect to the

gripper arms

34, 36 and in desired axial relation with respect to the bulb l I.

This desired axial relation is not disturbed when the tubulation is released and drops on to the bulb H. This is for the reason that the release is effected by a complete movement of the edge 40 of arm 36 away from the tubulation. This complete movement of edge 40 is possible because of the disposition of this edge adjacent the lower surface of the arm 36. This disposition of the edge displaces it vertically from the horizontal plane of pin 39 on which the arm 36 pivots. Consequently, the edge 40 travels in an arcuate path away from tubulation when the arm 36 is rotated by the force of the air jet from nozzle 44.

During the operation of sealing the tubulation I I] to the bulb l l a gas burner 48 shown in phantom may be employed to direct a sharp flame to the region of the seal to further soften the glass of the bulb and to force an opening in the bulb communicating with the interior of the tubulation.

It will be appreciated from the foregoing that a relatively simple and effective apparatus and method are provided for joining members capable of assuming a plastic state in response to heat. The apparatus and method of the invention are particularly advantageous in sealing a glass exhaust tubulation to a glass bulb to form a sub-assembly for an electron tube.

What is claimed is:

1. Apparatus for joining parts capable of becoming plastic in response to heat, comprising means for supporting one of said parts, means for heating a selected portion of said one of said parts to render it plastic, a holder for releasingly supporting another of said parts coaxially with and above said one of said parts, said holder having a vane, said vane being mounted at one end thereof for pivotal movement on a horizontal axis and having a mass for pinchingly engaging said another of said parts by the weight of said mass, said vane having a fiat undersurface, and means acting on said vane for releasing said holder, said last-named means comprising an air nozzle adjacent said under-surface and adapted to direct an air jet to said under surface for pivotally moving said vane against the weight of said mass thereof, for releasing said another of said parts, whereby said another of said parts falls by gravity to said selected portion for fusion therewith.

2. Apparatus for joining parts capable of becoming plastic in response to heat, comprising means for supporting one of said parts, means for heating a predetermined portion of said one of said parts to render it plastic, means for releasably supporting another of said parts above said one of said parts and in registry with said predetermined portion, said means including elements relatively movable for releasing said another of said parts, said elements including a pivoted member having a fiat face, and means for causing relative movement between said elements, said last-named means comprising a nozzle adjacent said flat face for causing said member to pivot out of engagement with said another of said parts, whereby said another of said parts is released and drops into abutment with said predetermined portion for joining said another of said parts to said portion.

3. Apparatus for joining glass parts, comprislng means for supporting said parts in a vertical array, means for heating an upper portion of the lower of said parts to render it plastic, and release means for releasing the support of the upper of said parts for causing said upper of said parts to drop onto the plastic upper portion of the lower of said parts for joining said parts, said release means including a pneumatic system comprising a conduit for gas under pressure, a valve across said conduit, a cam for intermittently opening and closing said valve, said support means including a releasable element for releasing the upper of said parts, said element having a flat surface, said conduit having a nozzle adjacent 7 said flat surface, whereby an air jet is directed against said fiat surface for releasing said upper .of saidparts.

4. Apparatus for fixing one end of a glass exhaust tubulation to the dome of a bulb for an electron tube, comprising means for supporting said .bulb with the dome thereof extending upwardly, additional means for supporting said tubulation in coaxial relation with respect to said bulb, and with one end of said tubulation adjacent said dome, means for heating said dome to a plastic state, said additional means including a vane having an edge supporting said tubulation, said vane being pivotally mounted for rotation on a horizontal axis for displacing said edge from said tubulation, and means for rotating said vane, said last named means comprising a pneumatic system including a nozzle adjacent said vane, whereby said tubulation is released from support by said additional means and is free to fall downwardly into abutment with said dome, for fusing said one end of said tubulation to said dome.

5. Apparatus for sealing a glass exhaust tubulation to the dome of an electron tube bulb, comprising means for supporting said tubulation axially of and above said bulb and with one end thereof adjacent said dome, said means includ-- ing a member having a V shaped end for embracing a portion of said tubulation, and a second member pivoted to said member and having an edge movable into and out of engagement with said portion of the tubulation in response to pivotal movement of said second member, said second member having a mass for normally maintaining said edge in contact with said portion in response to gravity, means for rotating said second member to displace said edge from said tubulation, said last named means comprising a nozzle for directing air under pressure to a surface of said second member, whereby said tubulation falls into abutment with said dome, and .means for heating said dome for sealing said tubulation thereto.

6. Apparatus for sealing a glass exhaust tubulation to a glass bulb having a closed end, comprising means for supporting said tubulation axially of and above said bulb, said means including a pivoted arm having a flat face and having an edge for frictionally engaging said tubulation in response to the weight of said arm and for releasing said tubulation in response to pivotal movement of said arm, and means for causing pivotal movement of said arm, said means comprising a nozzle adjacent said fiat face for directing an air stream to said fiat face, whereby said tubulation is free to fall downwardly into engagement with said plastic closed end of said bulb, for sealing said tubulation to said bulb.

'7. Apparatus for joining a glass exhaust tubulation to a glass bulb to form a sub-assembly for an electron tube, comprising a sealing station for fusing an end of said tubulation to said bulb, said station comprising means for heating said "bulb to soften a predetermined portion thereof,

a support for said tubulation, said support including a vane pivotally mounted and having an edge in engagement with said tubulation in response to the weight of said vane, said edge being movable out of said engagement in response to pivotal movement of said vane, and means at said sealing station for causing said pivotal movement, said means comprising a pneumatic system including a conduit for air under pressure having a nozzle against said vane for directing an air jet thereto, a valve across said conduit, and

ill

, a cam for opening said valve, whereby said tubulation is released, said support supporting said tubulation above said predetermined portion of the bulb, whereby said tubulation falls by gravity into abutment with said portion for fusing said tubulation to said portion.

8. Apparatus for sealing a glass exhaust tubulation to a glass bulb having a closed end to provide a sub-assembly for an electron tube, comprising means for supporting said bulb in an axially vertical position with said closed and extending upwardly, means for supporting said tubulation above said bulb and in axial relation therewith, said last named means including two members having edges for engaging different sides of said tubulation in a frictional grip, said members being relatively movable by gravity to grip said sides, means for causing relative movement of said members against the force of gravity thereon to release their grip on said tubulation, said last named means including a nozzle for directing an air jet against one of said members, whereby said tubulation falls by gravity into abutment relation with said closed end of the bulb, and means for heating said closed end to a plastic state for fusing an end of said tubulation to said closed end of the bulb for providing said sub-assembly.

9. Apparatus for joining by fusion one end of a glass exhaust tubulation to the closed end of a cup-shaped glass bulb, comprising means for supporting said bulb in an upright position with said closed end thereof extending upwardly, means for supporting said tubulation above said closed end and in coaxial relation with respect to said bulb, said last means including a movable member for releasing said tubulation in response to a force of predetermined magnitude and a fixed member for guiding said tubulation in a path coaxial with respect to said bulb when released by said movable member, means including a nozzle adjacent said movable member for directing an air jet having a force of said predetermined magnitude against said movable member, whereby said tubulation falls axially to abut a central portion of said closed end, and means for heating said central portion to a plastic state for fusing said tubulation to said closed end of said bulb.

10. Method of joining a glass exhaust tubulation to the closed end of a cup shaped bulb, comprising the steps of (1) supporting said bulb against rectilinear axial movement with the axis thereof extending vertically and with saidiclosed and extending upwardly, (2) releasingly supporting said tubulation in spaced relation above said closed end and coaxially with respect to said bulb, (3) axially rotating said bulb and tubulation in a plurality of cycles of rotation, (4) simultaneously releasin said tubulation for free fall during a relatively small portion of each of said cycles of rotation and guiding the tubulation in said fall in a path coaxial with respect to said bulb, whereby said tubulation is caused to move solely in response to gravity in a series of relatively short distance falls to a central portion of said closed end and in abutment relation therewith with reduced impact shock, (5) and heating said central portion to fuse said tubulation to saidclosed end of the bulb.

11. Apparatus for joining heat plasticizable parts, comprising supporting means for supporting one of said parts in a predetermined position, whereby a selected portion thereof extends upwardly, means for heating saidselected portion 9 to plastic form, a releasable holder mounted on said supporting means for supporting another of said parts above and in vertical registry with said selected portion, said holder including a member mounted at one end thereof for pivotal movement on a horizontal axis, said member including a relatively long portion extending to the other end thereof and having a flat face lying in the plane of said axis, means for rotating said supporting means on a vertical axis, whereby said flat face of said member is caused to move cyclically in a predetermined horizontal path, and means including an air nozzle adjacent and below said path for directing an air stream upwardly and across said predetermined path, whereby said air stream cyclically strikes said flat face during rotation of said supporting means for intermittently releasing said another of said parts.

JOHN V. RUGGIERO.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,626,683 Madden May 3, 1927 1,628,410 Koning May 10, 1927 1,789,011 Mailey et al Jan. 13, 1931 1,793,320 Horn Feb. 17, 1931 2,272,927 stager Feb. 10, 1942 2,553,135 Eisler May 15, 1951