US2961800A - Apparatus for forming glass envelopes and mounting operative elements therein - Google Patents

Description

' Nov. 29, 1960 E. E. BATES APPARATUS FOR FORMING GLASS ENVELOPES AND MOUNTING OPERATIVE ELEMENTS THEREIN 4 Sheets-Sheet 1 Filed June 28, 1955 IN V EN TOR.

VRETT E. BATES 5w, ATTORNEY,

Nov. 29, 1960 E. E. BATES 2,951,800

APPARATUS FOR FORMING GLASS ENVELOPES AND MOUNTING OPERATIVE ELEMENTS THEREIN Filed June 28, 1955 4 Sheets-Sheet 2 Ins 8O 79 i 89 a7 l. i 5 5 63 6 I z 3 62 72 I V 49 I 50 V Am Ill 29 96 74 IN VEN TOR: EVERETT E. BATES 2 W EMA ATTORNEY,

E. E. BATE-s 2,961,800 APPARATUS FOR FORMING cuss ENVELOPES AND MOUNTING OPERATIVE ELEMENTS THEREIN Nov. 29, 1960 4 Sheets-Sheet 3 Filed June 28, 1955 INVENTORI EVERETT E. BATES BY W mm, A "r'ro /v EY' Nov. 29, 1960 Filed June 28, 1955 E E BATES APPARATUS FOR FQ'RMI'NG GLASS ENVELOPES AND MOUNTING OPERATIVE ELEMENTS THEREIN 4 Sheets-*Sheet 4 FIG. [4

INVENTOR: EVER TT E. BATES ATTORNEY,

APPARATUS FOR FORMING GLASS ENVELOPES AND MOUNTING OPERA'IIVE ELEMENTS THEREIN Everett E. Bates, Marblehead, Mass, assignor, by mesne assignments, to Sylvania Electric Products Inc., Wilmington, Del., a corporation of Delaware Filed June 28, 1955, S01. No. 518,558

2 Claims. c1. 49-2 This invention relates to glass envelopes and more particularly an apparatus for enclosing operative elementsof electrical and electronic devices within such envelopes.

Countless different devices commonly encountered in the electrical and electronic industries employ operative elements positioned within evacuated or gas filled glass envelopes. In the fabrication of one type, lead-in wires connected to the operative elements are united to one end of a tubular envelope from which they extend outwardly. The other end of the envelope provides a pre-constricted passage and integral tube adapted to being subsequently inserted into an exhaust machine for evacuating, filling with gas if necessary and final tipping or sealing off. This invention is primarily directed to methods and apparatus for the manufacture of this type envelope and more specifically in one aspect to the manufacture of fluorescent.

lamp glow starters employing heat-responsive bi-metal elements within a glass envelope.

Various processes have been employed in the fabrication of these devices but each of these methods has presented serious problems. One method, for example, makes use of two tubes of different sizes first sealed together in axial alignment. The internal elements are then sealed within the larger tube, the smaller tube is thereafter available for insertion into a vacuum chuck of an exhaust machine for evacuation prior to final sealing. In this construction the internal elements may project somewhat into the restriction thereby being retained by the glass against outward displacement. The restriction servies the additional purpose of facilitating final closure of the envelope.

Sealing of the tubes together presents real difficulties in this construction. In the first place, random variations in heat intensity or irregularities in the end of either tube may result in an imperfect, incomplete seal, which must be rejected. A second disadvantage is that the operation of molding together tubes of different sizes sets up strains in the glass which render it susceptible to Sttes Patent ice bers, the tube is heated in the area in which a restriction is desired and is then stretched to form the restriction.

Such a process presents a major difficulty by bringing glass in its plastic state close to the operative elements. Internal elements which are even slightly misaligned may be embedded in glass in drawing the restriction. If this happens, the glass renders the finished article inoperativeby interfering with any required motion of the internal elements or by partially insulating them from one another. In severe cases of misalignment the envelope often cracks upon cooling. A further objection to this method lies in the fact that the internal elements may be damaged' by exposure to excessive heat while the tube is being heated to form the restriction.

Another object of my invention is to enclose. operative: elements within a glass envelope without allowing them is readily adjustable for uniformity of product and to compensate for wear.

It is an advantage of my invention that my process of fabrication not only lends itself to performance on a single machine but my apparatus is adapted to automatic' loading of component glass tubes and unloading of as sembhes at the completion of the cycle thereby reducing machine requirements while increasing operator productivity.

An important feature of my invention is that the internal elements are not present within the tube while the cracking in the area around the mold when the glass is I reheated for sealing to internal elements or tipping off. Another disadvantage is that this method yields an abruptly constricted glass structure which may be shattered by a misaligned internal element during the subsequent insertion of these elements. Since this process is not adaptable to performance on a single machine, it thereby increases the cost of production in addition to being inherently wasteful because of the shrinkage from the various causes enumerated. In addition to high cost, a further disadvantage lies in the fact that it is not economically feasible to form a smooth seal between the tubes and that the resultant product has a rough, unfinished appearance.

Another processheretofore employed makes use of a 7 single tube and is suitableto being performed on one lead-in Wires. While still being held by pressing me1n.

restriction is being formed. Therefore, the possibility that the glass might adhere to the internal elements is completely eliminated.

Another important feature is that my apparatus and operatlng cycle are so designed that the internal elements are never placed m the path of flames or other source of" heat required for forming and sealing.

Still another advantage of my invention is that it permits insertion of the internal elements into a heated, funnel-shaped restriction having a smooth contour.

form of' the restriction aids in positioning the internal. elements and the heated state of the glass greatly reduces The its frangibility.

These and other objects of the invention are attained 1n one of its embodiments by first heating a selected portion of a glass tube to the plastic state, elongating the tube to form a passage of reduced dimension or restriction in the heated portion, then positioning a mount of internal elements Within the tube while it is still hot and finally uniting the end of the tube to the mount.

Other objects and novel featuresof my apparatus will be apparent from the description of the invention whic follows.

Figure l is afragmentary view in perspective of a glass sealing machine embodying the apparatus.

Figure 2 is a view in cross-section taken along line 22 of Figure l.

Figure 3 is a view in cross-section taken along line 3-3 of Figure 2 Figure 4 is a view in cross-section taken along line 4'f4 of Figure 2.

Figure 5 is a view in cross-section taken along line 5-5 '5 of .Figure 2.

Figures 6 through 10 are simplified yiews of the appa-i ratus showing component parts in different relative positions during one complete cycle.

Figure 11 is a front elevation of an operative head showing burners projecting flames upon a tube carried by the head.

Figure 12 is a front elevation of an operative head showing burners projecting flames upon a restriction being formed in a tube.

Figure 13 is a front elevation of an operative head showing burners projecting flames upon the lower end of a tube to seal the end of the tube to a mount of operative elements.

Figure 14 is a timing chart showing positions assumed by relatively moving parts of the apparatus during one complete cycle.

In the various views, my apparatus has been shown as it is used in the fabrication of glow starter sub-assemblies but it must be understood that this has been done for illustrative purposes only. The invention may be adapted to the manufacture of a great variety of electrical and electronic devices by those familiar with the art although slight modifications within the spirit of the invention may be required.

Before describing Figure 1 in detail, it should be noted that the operation of the apparatus and the component parts of the product may be understood generally by a brief consideration of Figures 61(). In arriving at subassembly A, a restriction is first formed in a glass tube T. Then internal elements in the form of mount M are sealed within restricted tube T. Mount M comprises heat-responsive bimetal elements B connected to depending leads L (seen in Figure positioned in glass bead G.

Turning now to Figure 1, it will be seen that, in the fabrication of sub-assembly A, my apparatus is used in conjunction with a sealing machine indicated at 21 of the type commonly encountered in the manufacture of miniature electric lamps. This machine has a substantially horizontal base 22, on which is mounted turret or carrier 23, rotatable in a clock-wise direction, about vertical shaft 24. Drive gear is revolved continuously in the same direction at a relatively slow speed by shaft 24 to which it is keyed in a manner not shown. Turret 23 is indexed from station to station by a standard drive not shown in the drawings. Gear 25 is provided with protective guards 26 and 27. Manifolds 28 and 29 are fixed on base 22 and furnish fuel gas to supply line 30 through adjustment valves 31 and 32.

Mounted at the periphery of turret 23 are sixteen heads designated generally by reference character 33. Each head is moved by turret 23 in turn to sixteen stations numbered 1 to 16 for convenience of reference, thereby cornpleting an operating cycle. The fragment of turret 23 shown in Fig. 1 includes stations 1416 and 1-5. As each head is moved through a complete cycle, it is operated by engagement of cam followers 34 and 35 with cam tracks 36 and 37 (Figs. 2, 7 and 8, respectively. Each head 33 is rotated by a pinion 38 in engagement with drive gear 25 but the rotation may be arrested during a portion of the operating cycle by head positioning track 39 as will be explained below.

The operation of each head 33 will be understood from a more detailed description with particular reference to Figure 2. The whole head assembly is journaled for rotation as a unit in bearings 45 pressed into bore 46 in depending boss 47 of turret 23. Outer sleeve 48 is engaged by friction shoes 50, slidable in radial holes 49 in hub 51 of pinion 38 and urged inwardly against the periphery of sleeve 48 by garter spring 52. As has already been seen pinion 38 is revolved continuously by engagement with drive gear 25. The under side of flange 53 integral with sleeve 48 rests on the upper end of hub 51. Pinion 38 rotates on spacer 54 which is free around outer sleeve 48.- An anti-friction thrust bearing comprising washers 55, balls 56 and retainer 57 is provided at the lower end of sleeve 48. Yoke 58, fast on sleeve 48 by means of set screw 59 retains sleeve 48 against axial motion. At stations where it is desired to halt the rotation of the head as for loading component parts and unloading a subassembly, a head positioning track 39 engages roller 60 rotatably mounted on pin 61 in yoke 58. An alternative construction would be to key yoke 58 to inner sleeve 48 which would be threaded at its lower end to receive a lock nut. Inner sleeve 62 is slidably mounted in outer sleeve 48, being retained against rotation relative to the latter by plate 63 aflixed to flange 64 by screw 65. Plate 63 has a slot 66 at one end which engages post 67 as inner sleeve 62 is reciprocated and a second slot 68 at the other end to retain rod 69 against rotation as it is moved up and down. Header 70 is retained on pilot 71 of rod 69 by thread 72. Slot 73 in pilot 71 provides a nest for lead-in wires L. Orientation of slot 73 is maintained by flats 74 on header 70 which is provided with head 75 to limit the downward motion of rod 60. Bolt 76 is threaded into flange 64 and locked by nut 77 so that its head 40 acts as an adjustable stop for the downward travel of inner sleeve 62. Post 67 supports an upper clamp indicated at 110, while a lower clamp indicated at 115 is mounted on post 78 which is integral with plate 63. The upper clamp 110 (Figure 5) consists in a fixed jaw 79 secured to post 67 by means of screw 80 and a movable jaw 81 pivoted on the post and biased into contact with fixed jaw 79 by spring 82. Similarly the lower clamp 115 (Figure 4) consists in a fixed jaw 83 retained on post 78 by screw 84 and movable jaw 85 pivotally mounted on post 78 and biased into contact with fixed jaw 83 by spring 86.- Heel members 87 and 88 and toe members 89 and 90 of fixed jaws 79 and 83 form a vertical cradle to position tube T in axial alignment with rod 69.

In order to form a restriction in tube T, it is first gripped in clamps and and carried to a number of burner stations where it is heated. After it has reached a plastic state the tube is stretched by a downward motion of the lower clamp 115. At a later station, rod 69 is elevated to position mount M within the lower end of restricted tube T prior to sealing. Motions of lower clamp 115 and rod 69 are controlled by cam tracks 36 and 37. Cam follower 34, threaded in tapped hole 91 of rod 69 and locked by washer 92 and nut 93, is biased into engagement with cam track 36 by compression spring 94. Similarly cam follower 35 is adjustably fixed to inner sleeve 62 by threads 95 and locked in position by nut 96. Spring 97 maintains follower 35 in engagement with cam track 37. It should be noted that the position of rod 39 relative to inner sleeve 62 shown in Figure 2 has been arbitrarily chosen to illustrate the function of cam tracks 36 and 37. Actually, as will be seen later, followers 34 and 35 are never simultaneously in engagement with their respective cam tracks. The true relative positions assumed at various points of an operating cycle will best be seen in Figures 6 through 10.

A number of pieces of angle iron 98 secured to each cam track 37, as by welding for example, are used to fasten this track to base 22 by means of screws 99. In order to secure adjustability in the height of track 36, it is welded to a number of leveling screws 101, each retained at the required elevation above base 22 by a pair of opposed lock nuts 102, only one of which is shown in Figure 2. Head positioning track 39 is welded to brackets 103 each held in place on base 22 by a screw 104.

The mode of operation of my apparatus will be understood from a description of one complete cycle of one head 33 with particular reference to Figure 14 which is a typical timing chart. It will be seen that the level of upper clamp 110, represented by the top line on the chart, remains constant through the cycle. On the other hand the lower clamp 115 ascends to an upper level between stations 2 and 3 where it remains through station 7. At this point it starts descending to a lower level which is reae fil at station 8 and maintained through the remainder of the cycle. These motions of lower clamp 115 are accomplished by the engagement of cam follower 35 with cam track 37 as each head 33 is moved to successive stations. Head positioning track 39 halts the rotation of head 33 at a point before station 16 is reached and maintains the angular orientation of the clamps 110 and 115 until an intermediate point is reached between stations 3 and 4 where roller 60 (Figure 2) moves out of engagement with track 39. Except for the interval between stations 1% and 14 and when rod 69 is moved upwardly by the action of cam track 36 on follower 34, head 75 overlies plates 63 (Figs. 640) and its movements up and down coincide with those of lower clamp 115 and the contour of cam track 37.

At station 1, head 75 and lower clamp 115 being at their lower levels, as seen in Figure 6, a mount M is manually loaded into its nest in the upper portion of rod 69. Between stations 2 and 3 lower clamp 115 moves to its upper level to receive a component glass tube T at station 3 in the manner shown in Figure 7. The glass tube T is inserted into the clamps 110 and 115 by an automatic tube loading mechanism not shown which positions the lower end of the tube relative to lower clamp 115. As head 33 is carried to stations 4 through 7, the level of the lower gripping members is maintained and the section of tube T between upper and lower gripping members is heated at each station by flames from a pair of burners 100, seen in Figure 11. In Figure 14, pairs of burners 106 are denoted as circles at each of stations 4 through 8. Each pair of burners 100 and burners 105 shown in views 11-13 are supported by piping 30* through which they are supplied with fuel gas from manifolds 28 and 2.9 as shown in Figure 1. At station 7 tube T has been heated sufficiently to render it plastic. Between stations 7 and 8, lower clamp 115 descends to its lower level following the downward turn of cam track 37 with which follower 35 is in contact. This increase in the distance between clamps 116 and 115 forms a restriction in tube T. Another pair of burners 100, shown in Figure 12, is provided at station 8 to relieve any possible strains set up in tube T during formation of the restriction. Between stations 8 and 10 tube T is allowed to solidify. Then at station 10 the operation of sealing mount M to tube T starts as flames from a pair of burners 105 are directed to the lower end of tube T. Between stations 10 and 11 cam follower 34 on the lower end of rod 69 engages cam track 36, thereby inserting mount M into the lower end of tube T. In Figure 8 head 33 is shown at an intermediate position between stations 10 and 11 through which rod 69 is moved by the engagement of follower 34 with cam track 36. The upper level of rod 69 is reached at station 11 and maintained through station 13 as shown in Figure 9. At each of stations 10 through 14, flames from pair of burners 105 are directed to the lower end of tube T to form a seal between the tube and mount T as inner sleeve 48 is rotated continuously. Between stations 13 and 14 rod 69 is allowed to return to its lower level but heating is continued at station 14. Cooling is provided at station 15 and the rotation of sleeve 62 is stopped by head positioning track 39 to permit unloading at station 16. Although sub-assembly A may be taken ofi manually, it is generally removed by an automatic transfer arm and inserted into a vacuum chuck of an exhaust turret which is mounted on a common base adjacent to the sealing turret. On the exhaust turret, the envelope is evacuated, filled with a gas such as neon and E tipped or sealed off in a normal manner. The transfer and exhaust apparatus not shown in these drawings may be any one of a great variety common in the art.

Having thus disclosed my invention, many variations within its spirit will be readily apparent to those of ordinary skill in the art. For example, the number of burner stations required either for the restricting or the sealing operation may be increased or decreased. Again my method may be practiced and my apparatus used on a sealing machine turret having a greater or lesser number of stations. Therefore, it will be understood that the invention is not to be limited to the specific construction and arrangement of parts shown, but that they may be widely modified within the scope of my invention as defined by the appended claims.

What I claim is:

l. A machine for forming glass envelopes and mounting operative elements therein attached to lead-in wires comprising: a movable carrier mounted on a base, means for moving said carrier relative to said base, a plurality of fabricating heads mounted on said carrier, a first and second set of burners and a first and second cam track, each of said heads comprising means for gripping a glass tube including two clamps mounted in spaced relationship so that a selected portion between said clamps is moved in heat receiving relation with said first set of burners, one of said clamps being operatively coupled to said first cam track to increase the spacing between said clamps during a portion of the travel of said heads whereby a passage of reduced cross-section is formed in said selected portion, and a support means actuated by said second cam track for carrying said operative elements from a remote position to a sealing position within one end of said tube in the path of flames from said second set of burners whereby the glass of said end is rendered plastic and urged into sealing relationship with said leadin wires.

2. A machine for forming glass envelopes and mounting operative elements therein attached to lead-in wires comprising a movable carrier mounted on a substantially horizontal base, means for moving said carrier relative to said base, a plurality of fabricating heads mounted on said carrier, a first and second set of burners and a first and second cam track. each of said heads comprising an upper and a lower clamp mounted in spaced relationship for holding one of said glass tubes in an upright position so that a selected portion between said clamps is moved in heat receiving relation with said first set of burners, one of said clamps being operatively coupled to said first cam track to increase the spacing between said clamps during a portion of the travel of said heads, whereby a passage of reduced cross-section is formed in said selected portion, and a support means for carrying operative elements co-axial with said tube, said support means being slidable by engagement with said second cam track between a position substantially below said tube to an upper level in abutting relationship with the lower end of said tube in the path of flames from said second set of burners whereby the glass of said lower end is rendered plastic and urged into sealing relation with said lead-in wires.

References Cited in the file of this patent UNITED STATES PATENTS

Images