US3390033A - Method of separating frit sealed parts of an electron tube - Google Patents

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Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
  • H01J9/26—Sealing together parts of vessels
  • H01J9/263—Sealing together parts of vessels specially adapted for cathode-ray tubes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/50—Repairing or regenerating used or defective discharge tubes or lamps
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2893/00—Discharge tubes and lamps
  • H01J2893/0072—Disassembly or repair of discharge tubes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/82—Recycling of waste of electrical or electronic equipment [WEEE]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/11—Methods of delaminating, per se; i.e., separating at bonding face
  • Y10T156/1153—Temperature change for delamination [e.g., heating during delaminating, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49815—Disassembling
  • Y10T29/49821—Disassembling by altering or destroying work part or connector

Definitions

• This invention relates to a method of separating glass bulb parts of an electron tube which are sealed together with a glass frit material.
• cathode ray tube bulb includes a shallow bowllike glass faceplate panel and a glass funnel memher.
• the sidewall of the panel is butt sealed to the large end of the funnel with a glass frit material. Because of the relatively high cost of the panel and funnel parts, it is desirable, in the case of a defective tube, that the parts be separated so that they can be salvaged for re-use.
• either the panel or funnel is heated so that it expands outwardly relative to the other. Such differential expansion produces a shearing stress on the seal and causes the seal to fracture.
• the entire bulb is heated both inside and out to weaken the frit seal. The bulb is then pressurized to force the two parts apart, thereby fracturing the seal.
• two parts of an electron tube bulb which are sealed together with a glass frit are thermally processed to create a temperature differential between the interior and exterior surfaces there of.
• a temperature differential produces a bending stress in the seal which causes the seal to fracture.
• the thermal processing is preferably performed cyclically such as by alternately and substantially uniformly heating and then immediately cooling the exterior surfaces so as to produce a back and forth bending fatigue in the seal.
• FIG. 1 is a partial longitudinal section of a cathode ray tube on which the invention may be practiced;
• FIGS. 2 and 3 are enlarged sections of a portion of the tube of FIG. 1 illustrating various steps of processing in accordance with the invention
• FIG. 4 is a partial longitudinal section of the tube of FIG. 1 with parts broken away illustrating another step in the process according to the invention.
• FIG. 5 is a graph illustrating temperature differentials produced in accordance with the processing of FIG. 4.
• a cathode ray tube in FIG. 1, includes a glass bulb comprising a faceplate panel 14 and a funnel member 16.
• the panel 14 includes a saucer-shaped faceplate 18 hav- 3,390,033 Patented June 25, 1968 ing a short peripheral sidewall 20 extending therefrom.
• the funnel 16 includes a frusto-conical portion 22 having a cylindrical neck portion 24 extending from the small end thereof. The open end of the panel sidewall 20 and the large end of the funnel 16 are butt sealed together with a glass frit seal 26.
• the tube 10 may be of the shadow mask type and include a mosaic phosphor screen 28, a. multiapertured shadow mask electrode 30, and a plural beam electron gun apparatus 32.
• frit seal 26 Various compositions of glass frit material may be used for making the frit seal 26.
• zinc-lead-borate devitrifiable frits such as those described in US. Patent 2,889,952, issued June 9, 1959, to S. A. Claypoole have been widely used and are preferred because of their devitrifiable properties.
• the frit seal 26 is made by applying a ring of frit (provided in a suspension of paste-like consistency) to the funnel 16 and allowing it to dry. The panel 14 is then set on top of the frit ring and the assembly heated to cause a fusion of the frit to both the panel and funnel.
• the seal 26 normally includes an external bead 34, and an internal bead 36 as shown in FIG. 2.
• an acid etch treatment When an acid etch treatment is employed, it may be performed as illustrated in FIG. 2. As there shown, a spray of acid 38 is directed onto the bead 34 from a suitable nozzle 40. A plurality of nozzles 40 may be positioned around the periphery of the tube 10 to spray the entire length of the bead 34. Alternatively, the external bead 34 of the seal 26 may be submerged in an acid bath. Best results have been obtained when the acid etch is such as to substantially completely remove the bead 34, but with as little as possible undercutting of the seal 26. Such a removal is illustrated in FIG. 3 which shows that the resulting seal surface 42 is substantially a continuation of the exterior funnel surface 43. It has been found that if the seal 26 is excessively undercut, e.g. greater than 20 percent of the seal distance, chipping of the bulb parts frequently occurs when the seal is subsequently fractured.
• a thermal processing of the panel 14 and the funnel 16 adjacent to the seal 26 is performed, e.g., as illustrated in F268. 4 and 5.
• both the exterior surface 43 of the funnel 16 and the exterior surface 44 of the panel 14 in the region of the seal 26 are simultaneously heated such as by application of hot water thereto.
• the water may be applied by sprays 46 from suitable nozzles 48 so as to flow over both the funnel surface 43 and the panel surface 44 as indicated by the numeral 49'.
• a plurality, e.g. six, of the nozzles 48 may be employed and positioned around the entire periphery of the cathode ray tube bulb 10.
• the initial heating of the exterior surfaces 43 and 44 is ceased and a cooling thereof is then immediately employed.
• the cooling step may be performed in a manner similar to the heating step, viz., by application of water sprays 46 from the nozzles 48.
• Such a simuitaneous cooling of the ex terior surfaces 43 and 44 produces a bending stress in the seal 26 which is of the opposite sense from that produced by the initial heating of the surfaces.
• the cycles of alternate heating and cooling of the exterior surfaces 43 and 44 are continued until the seal 26 is fractured as a result of the back and forth bending fatigue induced therein.
• the exterior temperatures of the two bulb parts 14 and 16 at points A and B are substantially equal at any given time.
• the exterior surfaces 43 and 44 are substantially uniformly heated and cooled by the water sprays 46.
• FIG. illustrates a preferred heating and cooling schedule which has been successfully used in separating frit sealed panel and funnel parts of a rectangular inch cathode ray tube bulb.
• temperature readings are plotted along the ordinate and elapsed time of the cyclical thermal processing along the abscissa.
• the temperature readings are those as recorded by four thermocouples, A, B, C, and D positioned as shown in FIG. 4 on the exterior panel surface 44, the exterior funnel surface 43, the interior funnel surface 50, and the interior panel surface 51, respectively.
• thermocouples A and B As indicated on the graph of FIG. 5, hot water at a temperature of about 52 C. is applied to both of the exterior surface 43 and 44 for a period of three minutes. During this time the temperature of the exterior surfaces 44 and 43, as indicated by thermocouples A and B, rises rapidly from room temperature to approximately 52 C. within one minute and then levels off at that temperature. At the same time, the temperature of the interior funnel surface 50, as indicated by thermocouple C, although lagging behind that of the exterior funnel surface 43, rises to slightly above 50 C. The temperature of the interior panel surface 51, as indicated by thermocouple D, lags even further behind, rising to approximately 45.
• a spray 46 of 21 C. cold water from the nozzles 48 is flowed over both of exterior surfaces 43 and 44 for a period of approximately three minutes. During this time the surface temperatures of the panel and funnel drop as indicated by their respective curves. Then after this three minute spray with cold water, both of the exterior surfaces 43 and 44 are again heated with a 52 C. hot water spray 46, which causes the surface temperatures of the panel and funnel to again rise, this time as shown by their respective curves beyond the six minute mark on the graph.
• a fracture of the frit seal 26 has consistently occurred after about 6 minutes of elapsed time.
• the exterior surfaces 43 and 44 are at a substantially higher temperature than the interior surfaces 50 and 51.
• Such a temperature differential establishes that the fracture is occurring, not because of a lateral shear induced in the seal, but rather because of a bending fatigue as hereinbefore described.
• the temperatures and durations of application of the heating and cooling media may be adjusted to produce seal fracture after two, three, or more cycles of thermal processing. While the three cycle (heat-cool-heat) process described with reference to FIG. 5 has been found preferable for one design of rectangular 25 inch bulb, a twocyclc process may be successfully used, and may, in fact, be preferred for some other bulb designs. Generally speaking, the more extreme the temperatures of the heating and cooling, the fewer the number of cycles that are required to produce seal fracture. On the other hand, the less extreme the temperatures, the greater the number of cycles required, and the less likely the chance of injury to the bulb parts.
• the liquids may be sprayed onto only the panel 14 and allowed to flow over both the funnel and panel surfaces 43 and 44.
• the spray itself may be directed onto both the panel 14 and the funnel is.
• thermal treatment by means other than liquid spray may be used.
• hot and/or cold gases e.g. air
• the desired portions of the panel and funnel i.e., those portions adjacent to the seal 26 may be submerged in hot and/or cold liquid baths.
• any of these or other thermal processing procedures may be used provided they are such as to produce the desired temperature differential between the exterior surfaces 43 and 44 and the interior surfaces 50 and 51, whereby to produce the seal-fracturing bending stress.
• the choice of means for performing the thermal processing may, to a large degree, depend upon the type of cathode ray tube involved and the already existing condition of the electrode parts therein. For example, in the case of a shadow mask cathode ray tube having a good shadow mask electrode 30 therein, it is undesirable to introduce into the tube any heating medium such as hot water which would be corrosive to the mask electrode. In such a case, it is preferable to apply the thermal processing to only the exterior surfaces 43 and 44, or to use a non-corrosive treating medium such as dry air in thermally treating the interior surfaces 59 and 51.
• an additional optional step which may be used involves the application of low air pressure to the inside of the bulb.
• the neck of the tube it may be closed with a stopper 52 and air pressure applied to within the tube by a hose 54 connected between the stopper 52 and a source of compressed air 56.
• a pressure of about one lb. per sq. inch or less relative to the pressure on the exterior of the bulb is adequate.
• Such a pressure may be applied throughout all or any terminal part of the thermal processing of the bulb parts. For example, it may be applied only during the last thermal cycle before seal fracture.
• the method of separatin two glass parts of an electron tube bulb sealed together with a glass frit seal comprising the steps of: alternately and substantially uniformly heating and cooling the exterior surfaces only of both said parts adjacent to said seal in immediate succession to produce bending stress of alternating sense in said seal to thereby cause bending fatigue and fracture of said seal the temperatures of both of said exterior surfaces being substantially the same during said method.
• the method of separating a faceplate panel part from a funnel part of a cathode ray tube bulb, which parts are butt sealed together by a frit seal and which have an exterior and an interior surface comprising the steps of (a) flowing hot water over said exterior surfaces only of said panel and said funnel in the region of said seal, then immediately (b) flowing cold water over said exterior surfaces only of said panel and said funnel in the region of said seal, and then immediately (c) flowing hot water over said exterior surfaces only of said panel and said funnel in the region of said seal, the temperatures of both of said exterior surfaces being substantially the same during said method.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)

Description

Priority Applications (6)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23537962

Family Applications (1)

Country Status (6)

Cited By (24)

Citations (2)

• 1964
  • 1964-08-13 US US38936564 patent/US3390033A/en not_active Expired - Lifetime
• 1965
  • 1965-07-12 GB GB2939965A patent/GB1116073A/en not_active Expired
  • 1965-08-10 BE BE668127A patent/BE668127A/xx unknown
  • 1965-08-12 SE SE1057165A patent/SE308011B/xx unknown
  • 1965-08-12 DE DE19651496025 patent/DE1496025B2/en active Pending
  • 1965-08-12 NL NL6510536A patent/NL142014B/en not_active IP Right Cessation

Patent Citations (2)

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