US3340035A

US3340035A - Cathode-ray tube manufacturing apparatus

Info

Publication number: US3340035A
Application number: US399478A
Authority: US
Inventors: Thaddeus J Hajduk; Kowalski Fred
Original assignee: Rauland Borg Corp
Current assignee: Rauland Borg Corp
Priority date: 1964-09-28
Filing date: 1964-09-28
Publication date: 1967-09-05
Anticipated expiration: 1984-09-05

Description

Sept. 5, 1967 T. J. HAJDUK 3,340,035

CATHODE-RAY TUBE MANUFACTURING APPARATUS Filed Sept. 28, 1964 2 Sheets-Sheet l 2. T53 34 FIG.1

O O Q INVENTOR S Thaddeafirl 20 5 u 'Hd Kow Sept. 5, 1967 T. J. HAJDUK 3,340,035

CATHODERAY TUBE MANUFACTURING APPARATUS Filed Sept. 28, 1964 2 Sheets-Sheet 2 FIG. 3

VENTORS "if I 4 22 A 5 5o 7 THADDEU HAJDUK G| FRED :yALsm BY MMLA/ United States Patent 3,340,035 CATHODE-RAY TUBE MANUFACTURING APPARATUS Thaddeus J. Hajduk, Chicago, and Fred Kowalski, Park Ridge, [1]., assignors to The Rauland Corporation, Chicago, Ill., a corporation of Illinois Filed Sept. 28, 1964, Ser. No. 399,478 11 Claims. (Cl. 65-454) The present invention concerns an apparatus for making an electron gun assembly for a three-gun cathoderay tube such as currently used in color television receivers. The invention is directed, more particularly, to what is referred to as beading and comprises an improved apparatus for accomplishing this step in the manufacture of a multi-gun tube.

It is convenient to describe the invention in the environment of a cathode-ray tube in which the electron gun assembly includes cylindrical electrodes for controlling, forming and focusing into a beam electrons emitted by a heated cathode. It is common practice to provide each of the electrodes with mounting straps spaced on the external periphery of the electrode. If the electrode series of a gun is mounted on a suitable mandrel with interposed spacers, the electrodes may conveniently be arranged in a desired array and with chosen interelectrode spacings. Generally, the electrodes are rotatable on the mandrel to the end that their mounting straps may be aligned. If the straps are now embedded in elongated pillars of insulating material, referred to as beading elements, the electrode series will have been formed into an array with preselected interelectrode spacings.

This subassembly has been formed heretofore by depositing a beading element in a holder and heating an exposed surface thereof until it has softened. Thereafter, the electrode series supported on its mandrel is positioned over and in alignment with the beading element and the straps are then forced into its softened surface. After a suflicient cooling period, the bead sets and its affixation to the mounting straps of the electrodes is complete. Repeating this process puts a 'second bead on the other series of straps of the assembled electrodes and completes the subassembly. Although this practice is acceptable, it is time consuming and, accordingly, it has been proposed that both beads be applied at the same time. While such a procedure may be readily established for a single gun assembly, it presents formidable problems when attempted for a three-gun color tube assembly. In such an assembly, it is common practice to employ mechanical convergence so that the position of the electron guns relative to one another is most important and misaligning of the electrodes on their respective mandrels during the beading operation can easily lead to a reject assembly. And yet, it is highly desirable both to speed up the beading function and to perform it in a way which minimizes the possibility of impairing the electrode alignment. These objectives are satisfied through the apparatus to be described.

Accordingly, it is a principal object of the invention to provide an improved apparatus for performing the beading operation in the manufacture of a multi-gun assembly.

It is another and specific object of the invention to provide an apparatus for making the three-gun assembly of a color cathode-ray tube which minimizes the possibility of misaligning the gun elements relative to each other.

The three guns constituting the gun assembly of a tricolor cathode-ray tube individually include cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 on the external periphery thereof. The beading apparatus of the invention for assembling the three guns comprises a workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of the three guns to establish a preselected electrode array with predetermined interelectrode spacings and with the mounting straps of each of the guns in substantial alignment and in approximate parallel relation to straps of the remaining two guns. Three bead holders individually releasably hold an elongated beading element of insulating material for movement between a heating position and a beading position. Means are provided for heating one surface of each of the heading elements to a softened condition. There are further means for simultaneously displacing each of the bead holders from its heating position to its beading position to drive the straps of two of the guns into each one of the beading elements and for retracting each of the bead holders from its beading position after a predetermined cooling period.

The mechanism for displacing the bead holders preferably features a linkage system similar to that of an umbrella in that a sleeve, displaced along a vertical shaft, moves the three bead holders simultaneously. It is also preferred that the sleeve be crank driven to execute harmonic motion, moving slowly from the heating position, then accelerating to approach the beading position quickly and finally decelerating to be presented to the beading position with minimum impact.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIGURE 1 is an elevational view of the beading apparatus of the invention to be used in fabricating the gun assembly of a three-gun tri-color cathode-ray tube;

FIGURE 2 is a view, partially in section, taken along line 2-2 of FIGURE 1;

FIGURE 3 is an enlarged detailed view taken on line 33 of FIGURE 2; and

FIGURE 4 is an enlarged detailed view of the section designated by a line 4-4 of FIGURE 3.

The beading apparatus comprises a removable workholder or fixture 10. The use of a removable fixture is convenient in that it permits the components of the three guns to be assembled at one work station and then loaded into the beading machine to receive its beading elements. The workholder has a base 11 which supports three mandrels positioned at the apices of an equilateral triangle. As shown more clearly in FIGURE 3, base 11 has a central hub-like section 12 with three longitudinally extending apertures each of which receives one mandrel 13. The three mandrels, particularly a to the portions thereof which serve to support the gun electrodes during the beading ope-ration, are the same structurally with one portion of nearly the same dimension as the inner diameter of a cylindrical electrode G One end of electrode G has one or more orienting straps 16 to be received in slots 15 milled in the upper surface of hub section 12 of workholder 10. If electrode G is threaded over the mandrel with its tab 16 inserted into slot 15, this electrode is supported in a predetermined orientation and against rotation. The next element threaded over the mandrel is a spacer 17 which is followed by an electrode G One end of this electrode has a reduced diameter section and mandrel 13, likewise, has a reduced diameter section 18 which accommodates the smaller end of electrode G The next succeeding element of the stack is a spacer 19 followed by a' cylindrical electrode G One end of electrode G is closed but has a central aperture for admitting an electron beam. The mandrel is stepped down in dimension successively with a section 20 which corresponds to the opening provided in the reduced section of electrode G to a final section 21 which matches in diameter the aperture of electrode G and the beam aperture of a further electrode G which is spaced from G by a spacer 22.

The enlarged view of FIGURE 4 illustrates the location of the three mandrels at the apices of an equilateral gun triangle. This view also illustrates that the cylindrical electrodes are provided with mounting straps angularly spaced on their external periphery. More particularly, each electrode has a band 25 with a span of approximately 120 afiixed to its outer periphery and the free ends 26 of the band serve as the electrode mounting straps. Obviously, each mandrel 13 has a length sufficient to accommodate the electrode series and also to be received within its recess in hub section 12 as a support.

In the three-gun assembly, it is conventional practice to have the guns mechanically converged rather than being supported with their axes parallel to one another. This is done to ease the convergence problem of the color tube into which the gun assembly is to be incorporated. Since the guns are mechanically converged, it is helpful to arrange that at least two, if not all three, of mandrels 13 recede within hub 12 of fixture 10. Accordingly, the length of the mandrel is sufiicient to project through hub 12 and its lower extremity has a fitting 28 with a finger piece 28a that may be grasped by an operator to rotate the spindle about its own axis. There is also a locking flange 28b which may rest upon a stop 29 suspended from base 11. With this structure, the mandrel may be locked in the position shown in FIGURE 3 and retained in that position while the electrodes G G and

spacer elements

17, 19, 22 are threaded thereover. It is also retained in this position throughout the heading operation. When that operation has been completed and the subassembly is to be removed, finger piece 28a may be rotated to release the mandrel permitting it to descend within hub 12 and facilitating removal of the subassembly. The fixture is sufiiciently flexible if two of mandrels 13 are adjustable in the described fashion and a pair of such mandrels is illustrated in FIGURE 3. The third may or may not be permanently fixed in the beading position.

It will be observed in FIGURE 3 that a support post 30 extends vertically from hub 12 in parallel relation to an assigned mandrel 13 and the free end of each

spacer element

17, 19, 22 threads thereover. By variously shaping the cross section of this support post at different levels with a matching configuration at the terminal portions of the spacers, keying may be introduced to assist the operator in arranging the spacers only in their preferred order in the electrode stack. Of course, a similar support post is associated with each of the three mandrels.

A pressure pad 31 rests within electrode G It may be put under pressure to clamp the electrodes during a bead ing operation. To that end, the pad is carried at the free end of a clamp lever 32 which is pivoted at 33 to a stand 34 secured to base 11. A handle 36 is also pivoted to stand 34 at point 36a and is coupled to lever 32 by means of a link 37 pivoted at 37a to handle 36 and at 37b to lever 32. Link 37 also carries a pressure block 370 for engaging lever 32 acting as a stop. A compression spring 35 is interposed between pad 31 and lever 32. If handle 36 is rotated clockwise about its pivot 36a, lever 32 rotates in the same direction about its pivot 33 and pad 31 is moved clear of the axis of mandrel 13, freeing the mandrel for loading or unloading. When the mandrel has been loaded with electrodes 6 -6 and the interelectrode spacers, preparatory to a beading operation, handle 36 is rotated in a counterclockwise direction to the position shown in FIGURE 3. This moves lever 32 in the same direction and inserts pad 31 into electrode G Stop block 370 rests on lever 32 and all

pivots

36a, 37a and 37b are in substantial alignment locking lever 32 against upward movement until such time as handle 36 shall have been rotated in a clockwise direction. Consequently, the electrode stack supported by mandrel 13 is clamped under pressure during the beading operation.

As shown in the enlarged view of FIGURE 4, base 11 has three arms extending from hub 12 and spaced approximately 120 apart. A rod 40 extends downwardly from each of the radial arms of base 11 and collectively the three rods serve as legs upon which fixture 10 is able to rest while the electrode elements and spacers are threaded on the several mandrels, this of course being accomplished at a loading station and not with the fixture installed in the beading machine.

Again with particular reference to FIGURE 4, it is clear that in threading electrode elements over mandrels 13, bands 25 of all electrodes are positioned inwardly toward the center of the gun assembly. Additionally, the straps 26 are formed or shaped so that when the .electrodes are properly oriented about their individual mandrels, the electrode straps of each gun are in approximate parallel relation to electrode straps of the remaining two guns. This is illustrated in FIGURE 4 and the precise orientation is achieved by means of a spline gauge 43. The spline gauge has a web at the top and'three depending fingers 43a, one shown in FIGURE 3, which may be threaded down between the pairs of the parallel arranged straps 26 to establish the desired orientation of the various electrode series. Gauge 43 is retained in position throughout the beading process.

Workholder 10 is removably installed in a framework secured to the horizontal or table portion 45 of the beading machine. The frame has three elements 46 which are essentially Z-shaped and, as shown in FIGURE 3, a thin plate 47 extends from the under face of the top'free end of each such element to serve as a shelf .upon which one arm of fixture base 11 may rest. It is essential that workholder 10 not only be supported within the beading apparatus but it must also be properly oriented in order that the beading elements may be presented in a proper relation to electrode straps 26 to which they are to be attached. For that reason, one end 46a of each of the support elements 46 serves as a stop against which the arm of base 11 which it supports is to come to rest in determining the orientation of fixture 10 within the beading machine. As indicated in FIGURE 4, stop portion 46a may have a flange section under which an arm of base 11 is to slide so that once the fixture has been properly horned within the beading machine it must be rotated in a counterclockwise direction to be removed. This facilitates an interlock protection that will be described. One of the support elements 46 carries a clamp (FIGURE 2) which may be manually closed against one of the arms of base 11 of fixture 10 to retain the fiixture locked securely in position in the beading machine. The detail of FIGURE 4 shows the clamp 80a engaging an arm of base 11 in this locking function.

The interlock to which reference has been made is designated 52 in FIGURE 2. It is supported on horizontal shelf 45 of the heading machine and is a microswitch 52 with a switch operator 52a projecting radially inwardly toward the center of fixture 10 but beneath the'level of its base 11. In this position, it is in the path of a leg 40 of the fixture so that counterclockwise rotation of'the fixture required to release it from the beading machine actuates microswitch 52.

The beads to be attached to the electrode straps are made of glass or insulating ceramic material and are releasably held by three bead holders for movement between a heating position and a heading position. One of the three bead holders 51 is shown in detail in FIGURES 3 and 4. It comprises a block 51a with a slot 51b dimensioned to receive one of the beading elements 50.It is preferred that the slot be electro-polished to prevent the slot 51b by spring-pressed fingers or clamps 51c, 51d

a) pivoted to the body of holder 51 and urged in clamping positions by springs 51e. Each finger may engage an end of bead 50 releasably to retain the bead within slot 51b of holder 51.

It would be unproductive to perform a beading cycle unless each of the three holders 51 contained a beading element. Consequently, each holder 51 accommodates a microswitch 51 that may be actuated by a finger portion 51g of clamp 51c. With a beading element in position, microswitch 51 will have been actuated to permit the beading operation to be pe formed, whereas in the absence of a beading element, finger 51c assumes an extreme clockwise position and opens microswitch 51 to prevent a beading cycle. As illustrated in FIGURE 3, holder 51 is in a heading position presenting bead 50 to the aligned electrode mounting straps 26.

The heating position of the bead holder is that shown in FIGURES 1 and 2 where the means for heating one surface of each beading element 5! to a softened condition are heaters 53. There is associated with each heater a pair of starting electrodes 53a. These electrodes are energized when it is desired to ignite the heater in order to soften beads 50 in the heading cycle. The conduits 53b indicate gas lines which feed the heaters.

Movement of each holder 51 between its heating and beading positions is along a median line of the gun triangle. To that end, each bead holder 51 is pivoted at 51h to a sleeve 45a affixed to the frame of the machine and is moved by means of links 54 which connect at one end to the bead holder so that movement of link 54 may displace the bead holder about its pivot 51h. Preferably, an eccentric is employed as the pivot pin coupling link 54 to holder 51 in order to facilitate adjustment of the beading depth. Since the three-gun beading machine has three such holders there are three links 54 and a common actuator connects to their free ends in order that they may be displaced simultaneously. Preferably, the common actuator is a sleeve 54a (FIGURE 1) slidable upon a vertical post 54b which is disposed coaxially of the triangle including the gun mandrels. That is to say, the axis of post 54b extends through the center of the gun triangle. Sleeve 54a has three flanges 54c and a pin pivotally connects each flange to the lower end of a link 54. Post 54b is supported by sleeve 45a and a shelf 45b constituting a part of the stationary frame of the beading machine.

In order to accomplish a beading cycle, it is necessary to slide sleeve 54a first vertically upwardly and then downwardly of post 54b. This is accomplished by means of a driving motor 75 which is coupled through a speed re ducing arrangement 75a to a solenoid controlled halfrevolution clutch 75b. The clutch affords a coupling to a crank 750 which connects to one end of a pivoted lever 75d. The opposite end of that lever terminates in a fork 752 which engages pins 75 projecting from opposite sides of sleeve 54a. This completes a coupling frommotor 75, through the speed reduction arrangement 75a, clutch 75b, crank 75c and lever 75d to sleeve 54a.

A programming arrangement 62, not shown in detail because it is of conventional construction, controls the circuitry by which the machine is placed into operation to perform the heading cycle when a starting switch (not shown) has been actuated. The circuits programmed thereby include the control for the solenoid which permits clutch 75b to respond and institute a half revolution drive of the clutch at particular intervals in the beading cycle. It further includes an excitation circuit for ignition electrodes 53a to fire heaters 53 only during certain program intervals. And, its control circuits further include

microswitches

51f and 52 arranged so that beading cannot be accomplished unless each workholder 51 contains a bead ing element 50 and also preventing what is known as double beading.

In describing the operation of the beading apparatus, it will be assumed that fixture is initially removed from the beading machine and is to be loaded with the cylindrical electrode elements from which a three-gun assembly is to be fabricated. With fixture 10 in its loading station, finger portions 28a are manipulated to raise mandrels 13 and lock them in the position shown in FIGURE 3. It is assumed now that all three mandrels are elevated and in position to receive the electrode elements. The loading is the same for each mandrel.

First grid G is placed on the mandrel and oriented by inserting tab 16 into slot 115. This is followed by stacking on the mandrel spacer 17, grid G spacer 19, grid G spacer 22 and finally grid G Each electrode is positioned with its band 25 facing toward the center of the gun triangle. When all of the mandrels have been threaded or loaded with these elements, spline gauge 43 is inserted between the aligned and approximately parallel pairs of straps 26 as indicated in FIGURE 4. The spline gauge orients electrodes G G from or with reference to electrode G which is held against rotation by its tab 16 which is nested within slot 15 of base 11. This establishes the electrodes of each gun in a preselected array on its mandrel with predetermined interelectrode spacings and with the mounting straps of each gun in alignment and in parallel relation to straps of the other two guns. Handle 36 is now rotated in a counterclockwise direction to bring clamp pad 31 into electrode G of one gun and to apply a clamping pressure to all the electrodes thereof. This clamping is similarly performed for each of the gun assemblies and fixture 10 is now loaded and ready to be installed in position in the beading machine.

It will be assumed that sleeve 54a is in its lowermost position (FIGURE 1) presenting all the bead holders 51 to the heating position. The frame 46 for receiving beading fixture -10 is now readily accessible and the fixture is inserted, resting upon shelves 47 and turned in a clockwise direction to home the arms of base 11 against stops 46a. Lock is now actuated releasably locking fixture 10 in the beading machine and with the appropriate orientation.

While holders 51 are in the heating position and heaters 53 are olf, an operator manually loads the heading elements 50 in each such holder. Loading of the bead in each holder actuates microswitches 51 which is necessary to condition timer 62 to control a beading cycle. When holders 51 have all been loaded and fixture 10 has been properly secured in position, the starting switch is actuated. It is distinctly preferred that the machine be provided with a pair of starting switches requiring the operator to use both hands to initiate the cycle. These switches are placed at the peripheral portion of the machine so that the operator must be away from the heaters before the starting switches may be actuated.

When the starting switch has been closed, timer 62 is energized and applies a potential for a very short interval to starting electrodes 53a of each heater. The timer also opens a valve (not shown) which supplies gas to the heaters which are now fired. The fires are trained on the exposed face of each bead 50 and after a suitable heating interval, usually three seconds, that surface of the beads becomes sufficiently soft that a mounting strap may readily be inserted into it. At this point, timer 62 shuts off the gas supply to the heaters.

After the heating interval has passed, timer 62 energizes the solenoid controlling clutch 75 to permit one half revolution. In this half-revolution of the clutch, crank 75c and lever 75d slide sleeve 5411: up post 54b. This simultaneously displaces each of bead holders 51 from its heating position of FIGURE 1 along a median line of one side of the gun triangle to its beading position of FIGURE 3. The softened surfaces of the beads are driven against electrode straps 26, each bead being driven against two aligned and parallel series of straps 26. Since the arrangement is symmetrical and the beads are applied simultaneously with the same force against the three alignments of mounting straps, the forces are symmetrical and balance out so that there is no net force tending to disturb the .alignment of the electrodes on their mandrels. Moreover, the halfrevolution clutch 75b causes the motion or action of bead holders 51- to be harmonic, that is to say, the action starts slowly and smoothly, accelerates rapidly and then terminates in a smooth, constant deceleration. This permits fast action of the bead holders to prevent chilling of the beads and yet presentation of the beads to straps 26 without a shock force that would tend to distort and disturb the alignment accuracy of the guns in the gun triangle. Holders 51'are retained in their beading position for a cooling period during which the beads set and become integrated with straps 26. An interval of 15 seconds is usually sufficient. After the cooling interval, program timer 62 again energizes clutch 75d and sleeve 54a is returned to the position of FIGURE 1, displacing holders 51 from the beading to the heating position. Inasmuch as each holder releasably supports a bead 50, the return of the holders to the heating positions strips the beads from the holders, leaving the beads in an integrated assembly with the electrode series of the three-gun assembly. At this juncture, timer 62 will have completed its cycle, a heading operation shall have been finished and the machine shut oil.

The operator may now remove fixture 10 from the machine. This is accomplished by rotating the fixture in a counterclockwise direction which actuates microswitch 52 and prepares timer 62 for the next succeeding beading operation. With the fixture removed from the heading machine, spline gauge 43 is removed from the gun assembly. This is accomplished by inserting a knock out pin in the center and at the bottom of the multi-gun assembly. Finger pieces 28 are again manipulated to withdraw mandrels 13 from the gun assemblies. The assembly may now be removed from the workholder and its spacer elements may, likewise, be withdrawn freeing the completed three-gun assembly. This is to say, completed insofar as the electrodes have been secured to insulating posts 50 to maintain the electrodes in a preselected array with a predetermined interelectrode spacing and with a predetermined electrode alignment.

Switch 72 must be actuated before a second beading cycle is initiated and actuation of this switch is accomplished by removing workholder 10 from the machine. Accordingly, double beading or a multiplicity of beading cycles cannot be performed on a single assembly of electrode elements.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broader aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of said guns to establish therfor a preselected electrode array with predetermined interelectrode spacings and with said mounting straps of each of said guns in substantial alignment and in approximate'parallel relation to straps of the remaining two guns;

three bead holders for individually releasably holding an elongated beading element of insulating material for movement between a heating position and a beading position;

means for heating one surface of each of said beading elements to a softened condition;

and means for simultaneously displacing each of said head holders from its heating position to its beading position to drive said straps of two of said guns into each of said beading elements and for retracting each of said bead holders from its beading position after a predetermined cooling period. 2. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of said guns to establish therefor a preselected electrode array with predetermined interelectrode spacings and with said mounting straps of each of said guns in substantial alignment and in approximate parallel relation to straps of the remaining two guns;

and means for simultaneously displacing each of said head holders from its heating position to its beading position to drive said straps of two of said guns into each of said beading elements and for retracting each of said bead holders from its beading position after a predetermined cooling period, said displacing means moving said bead holders with equal force along median lines of said triangle to exert balanced pressures against said guns.

3. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

.a workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of said guns to establish therefor a preselected electrode array with predetermined interelectrode spacings and with said mounting straps of each of said guns in substantial alignment and in approximate parallel relation to straps of the remain ing two guns;

three bead holders for individually releasably holding an elongated beading element of insulating material and individually mounted for pivotal movement along a median line of said triangle between a heating position and a beading position;

means for heating one surface of each of said beading elements to a softenedcondition;

and means for simultaneously displacing each of said bead holders from its heating position to its beading position to drive said straps of two of said guns into each of said beading elements and for retracting each of said bead holders from its beading position after a predetermined cooling period said displacing means comprising a mechanism for efiecting harmonic motion of said bead holders between its aforesaid positions.

4. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of said guns to establish therefor a preselected electrode array with predetermined interelectrode spacings'and with said mounting straps of each of said guns in substantial alignment and in approximate parallel relation to straps of the remaining two guns;

a link for each of said bead holders connected at one end to its associated bead holder for effecting pivotal displacement thereof between a heating position and a heading position;

a common actuator connected to the other end of each -of said links and displaceable to move said three bead holders simultaneously;

and a timer for displacing said actuator to move said bead holders to said beading position after said beading elements have been softened and to return said bead holders to said heating position after a given cooling period.

5. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

three bead holders for individually releasably holding an elongated beading element of insulating material and individually mounted for movement along a median line of said triangle between a heating position and a heading position;

a link for each of said bead holders connected at one end to its associated bead holder for effecting displacement thereof between a heating position and a heading position;

a vertical support extending coaxially of said triangle;

a sleeve slidable on said vertical support and connected to the other end of each of said links to move said three bead holders simultaneously;

and means for displacing said sleeve along said vertical support.

6. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

three bead holders for individually releasably holding an elongated beading element of insulating material and individually mounted for movement along a median line of said triangle between a heating position and a beading position;

a link for each of said head holders connected at one end to its associated bead holders for eifecting displacement thereof between a heating position and a beading position; a vertical support extending coaxially of said triangle; a sleeve slidable on said vertical support and connected to the other end of each of said links to move said three bead holders simultaneously; and means including a drive motor, a half-revolution clutch, and a crank connected to said sleeve for displacing said sleeve along said vertical support. 7. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately degrees on the external periphery thereof, said apparatus comprising:

clamps included in said workholder and individually associated with one of said mandrels for maintaining the electrode array of each of said mandrels under a predetermined clamping pressure during the beading operation;

and means for simultaneously displacing each of said bead holders from its heating position to its beading position to drive said straps of two of said guns into each of said beading elements and for retracting each of said bead holders from its beading position after a predetermined cooling period.

8. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of said guns to establish therefor a preselected electrode array with predetermined interelectrode spacings and with said mounting straps -of each of said guns in substantial alignment and in approximate parallel relation to straps of the remaining two guns;

each of said head holders including a pair of spring pressed clamps for engaging the opposite ends of one of said beading elements;

and means for simultaneously displacing each of said bead holders from its heating position to its beading position to drive said straps of two of said guns into each of said beading elements and for retracting each of said head holders from its beading position after a predetermined cooling period.

9. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

a workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of said guns to establish therefor a preselected electrode array with predetermined interelectrode spacings and with said mounting straps of each of said guns in substantial'alignrnent and in approximate parallel relation to straps of the remaining two guns;

means for simultaneously displacing each of said head holders from its heating position to its beading position to drive said straps of two of said guns into each of said beading elements and for retracting each of said bead holders from its beading position after a predetermined cooling period;

and a program timer for firing said heating means for a given interval at the start of a heading cycle, and for controlling said displacing means to move said bead holders to said beading position after said given interval and to displace said bead holders from said beading position to said heating position after a given cooling period.

10. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

a removable workholder including three mandrels positioned at the apices of an equilateral triangle for individually supporting the electrodes and interposed spacing elements of each of said guns to establish therefor a preselected electrode array with predetermined interelectrode spacings and with said mounting straps of each of said guns in substantial alignment and in approximate parallel relation to straps of the remaining two guns;

a program timer for firing said heating means for a given interval at the start of a beading cycle, and for controlling said displacing means to move said bead holders to said beading position after said given interval and to displace said bead holders from said beading position to said heating position after a given cooling period;

and an interlock actuated by removal of said workholder for conditioning said program timer for controlling a heading cycle.

11. Apparatus for making a three-gun assembly for a cathode-ray tube individually including cylindrical electrodes each of which has a pair of mounting straps angularly spaced approximately 120 degrees on the external periphery thereof, said apparatus comprising:

means for simultaneously displacing each of said bead holders from its heating position to its beading position to drive said straps of two of said guns into each of said beading elements and for retracting each of said bead holders from its beading position after a predetermined cooling period;

and interlocks actuated in response to the positioning of said beading elements in said head holders for preparing said apparatus to initiate a heading cycle.

References Cited UNITED STATES PATENTS 2,600,076 6/1952 Schelling 65l55 XR 2,707,848 5/1955 'Pityo 65-155 XR 2,950,568 8/1960 Kissinger et a1. 65l54 DONALL H. SYLVESTER, Primary Examiner.

F. W. MIGA, Assistant Examiner.

Claims

1. APPARATUS FOR MAKING A THREE-GUN ASSEMBLY FOR A CATHODE-RAY TUBE INDIVIDUALLY INCLUDING CYLINDRICAL ELECTRODES EACH OF WHICH HAS A PAIR OF MOUNTING STRAPS ANGULARLY SPACED APPROXIMATELY 120 DEGREES ON THE EXTERNAL PERIPHERY THEREOF, SAID APPARATUS COMPRISING: A WORKHOLDER INCLUDING THREE MANDRELS POSITIONED AT THE APICES OF AN EQUILATERAL TRIANGLE FOR INDIVIDUALLY SUPPORTING THE ELECTRODES AND INTERPOSED SPACING ELEMENTS OF EACH OF SAID GUNS TO ESTABLISH THERFOR A PRESELECTED ELECTRODE ARRAY WITH PREDETERMINED INTERELECTRODE SPACINGS AND WITH SAID MOUNTING STRAPS OF EACH OF SAID GUNS IN SUBSTANTIAL ALIGMENT AND IN APPROXIMATE PARALLEL RELATION TO STRAPS OF THE REMAINING TWO GUNS; THREE BEAD HOLDERS FOR INDIVIDUALLY RELEASABLY HOLDING AN ELONGATED BEADING ELEMENT OF INSULATING MATERIAL FOR MOVEMENT BETWEEN A HEATING POSITION AND A BEADING POSITION; MEANS FOR HEATING ONE SURFACE OF EACH OF SAID BEADING ELEMENTS TO A SOFTENED CONDITION; AND MEANS FOR SIMULTANEOUSLY DISPLACING EACH OF SAID BEAD HOLDERS FROM ITS HEATING POSITION TO ITS BEADING POSITION TO DRIVE SAID STRAPS OF TWO OF SAID GUNS INTO EACH OF SAID BEADING ELEMENTS AND FOR RETRACTING EACH OF SAID BEAD HOLDERS FROM ITS BEADING POSITION AFTER A PREDETERMINED COOLING PERIOD.