US3909928A - Method for manufacturing a shadow mask - Google Patents

Method for manufacturing a shadow mask Download PDF

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Publication number
US3909928A
US3909928A US444569A US44456974A US3909928A US 3909928 A US3909928 A US 3909928A US 444569 A US444569 A US 444569A US 44456974 A US44456974 A US 44456974A US 3909928 A US3909928 A US 3909928A
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United States
Prior art keywords
sheet steel
annealing
skin
holes
forming
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US444569A
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English (en)
Inventor
Kazuo Sato
Soji Takahashi
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Hitachi Ltd
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Hitachi Ltd
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Filing date
Publication date
Priority claimed from JP48020167A external-priority patent/JPS5244868B2/ja
Priority claimed from JP48075358A external-priority patent/JPS5023317A/ja
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
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Publication of US3909928A publication Critical patent/US3909928A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/14—Manufacture of electrodes or electrode systems of non-emitting electrodes
    • H01J9/142—Manufacture of electrodes or electrode systems of non-emitting electrodes of shadow-masks for colour television 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
    • 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
    • Y10T29/496—Multiperforated metal article making
    • 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
    • Y10T29/49995—Shaping one-piece blank by removing material
    • 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
    • Y10T29/49995—Shaping one-piece blank by removing material
    • Y10T29/49996—Successive distinct removal operations

Definitions

  • a sheet steel is annealed and is subjected to skin-pass rolling of a reduction of 0.515% before forming a desired pattern of small holes therein with an etching (i.e. photoetching) method, thereby to provide a sheet steel having no elongation of the yield point and being slow in aging and to decrease the thermal deformation of the shadow mask by applying the residual stress occurring therein due to the skin-pass rolling.
  • an etching i.e. photoetching
  • FIG. 1 ROLLING ANNEALING SKIN PAS @LING ETCHING R ESS FORMING TENSION 0 COMPRE55
  • This invention relates to improvements in a method for manufacturing a shadow mask, and more particularly to a method for manufacturing a shadow mask of a Braun tube for color TV.
  • a shadow mask has heretofore been manufactured by employing as a material a low carbon steel whose content of carbon is not greater than 0.1% and by rolling the material to athickness'of or below approximately 0.2 mm., thereafter forming holes in the steel sheet with photoetching (in, for example, the shadow mask of a color TV Braun tube, several hundred thousands of holes are arrayed under a predetermined pattern in case of the inch tube) and press-forming the steel sheet into the shadow mask.
  • photoetching in, for example, the shadow mask of a color TV Braun tube, several hundred thousands of holes are arrayed under a predetermined pattern in case of the inch tube
  • press-forming the steel sheet into the shadow mask in general, sheet steel subjected to a high degree of cold rolling down to the thickness of or below 0.2 mm. does not have enough ductility to withstand the press forming. Even if the forming is possible, the amount of spring-back after the forming is large on accountof a high flow stress.
  • the sheet steel is usually annealed. Since the annealed sheet steel has a yield point elongation of several percent, small wrinkles 'or lines termed the stretcher strain arise at the press-forming. In order to prevent the stretcher strain and to erase the wave in the sheet steel'caused by the annealing, the sheet steel after the annealing needs to be further treated by a'leveler. I i
  • a first object of this invention is to eliminate the above-mentioned disadvantages and to obtain a material which does not distort the pattern of the'holes in the mask surface and which is difficult to induce the shadow mask surface, the deformation of the sheet plane is small.
  • FIG. 1 is a process chart showing a method according to this invention for manufacturing a shadow mask
  • FIG. 2 shows stress strain diagrams in the respective steps of this invention
  • FIGS. 3a-3d are diagrams showing the residual stress distributions of a material in the respective steps of this invention.
  • FIG. 4 is a diagram showing the relationship between the skin-pass reduction in height and the yield point elongation of the material.
  • FIG. 5 is a diagram showing the relationship between the skin-pass reduction in height and the uniform elongation as well as the total elongation of the material.
  • FIG. 1 is a process ehartwhic'h shows the method according to this'invention for manufacturing a shadow mask. After the rolling and before the etching perforation, the material is annealed and is further subjected to the skin-pass rolling. Thus, the material having quite no yield point elongation and being slow in aging is obtained, and the working process as shown in this figure is made possible. It is also possible to decrease the amount of thermal deformation of the shadow mask by utilizing a residual stress within the material as attributed to the performance of the skin-pass rolling.
  • a working process for manufacturing a, mask of a sheet thickness of 0.150 mm. is taken as an example of this invention, and will be described in regular sequence.
  • FIG. 2 shows'the stress-strain diagrams of a material in the respective steps of this invention.
  • low carbon steel or mild steel (which may also be industrial pure iron) having a carbon content of 0.060.08%'by weight and being a starting material is subjected to a cold rolling operation, to obtain sheet steel which is 0.152 mm. thick.
  • the stress-strain diagram of the material in this state is illustrated at A in FIG. 2.
  • the property of the sheet steel in this state- is the same as that of sheet steel after the rolling opera tion in the prior art.
  • the sheet steel becomes a material which is large in elongation as shown at Bin FIG. 2.
  • an inert gas e.g. N or H
  • the material in theinvention isfree from the wave formation in the sheet plane and is good in flatness, but it has a large yield point elongation.
  • the material is subsequently formed with holes by etching in the general procedure conventionally used in the production of shadow masks.
  • the perforated material is press-formed as it is (although the technique known as cold forming is usually adopted to effect press-forming, the use of the technique known as hot forming is not objectionable).
  • the skin'pass rolling or temper rolling is highly effective in preventing the stretcher strain.
  • the shadow mask formed via the skin-pass rolling as in the foregoing example is lessened in the amount of thermal deformation even in the presence of a local temperature rise, for a reason stated below.
  • FIGS. 3a3d are diagrams showing the residual stress distributions of the material in the respective steps of this invention.
  • the steel in this state is especially suitable as the sheet steel for the shadow mask in comparison with the steel in the prior art shown in FIG. 3a.
  • the sheet steel after the skin-pass rolling as shown in FIG. 3b is further subjected to the etching operation by which, as has hitherto been performed, the holes are formed so as to be larger on one side (fluorescent screen side) than on the other side (electron gun side). Then, as shown in FIG. 30, the residual stresses change to a distribution which consists of a large compression on the smaller aperture side and zero compression and a tension over from thesurface to the central part on the larger aperture side.
  • the shadow mask with such bending moments exerted thereon is under the action of a force of suppressing expansion and therefore diminishes in the amount of thermaldeformation even at the application of the local temperature rise.
  • the etching rate on the larger aperture side is made greater than on the smaller aperture side at the post-etching after the forming as has hitherto been well known, the residual stress distribution is intensified, and hence, the effect of diminishing the thermal deformation is increased.
  • the range of the reduction (in height) of the skinpass rolling is prescribed by conditions in the working to be set forth hereunder.
  • the lower limit of the reduction is prescribed, depending on whether the yield point elongation can be decreased or not.
  • a reduction value of at least 0.5% (desirably, at least 1.0%) is considered to be suitable.
  • the appearance of the stretcher strain is preveritable.
  • the upper limit of the reduction is prescribed by the ductility of the material.
  • the relationship between the reduction and the uniform strain as well as the total strain is illustrated in FIG. 5. Since a ductility of several percent is required at the press-forming operation, the upper limit of the reduction is approximately 15%.
  • the temperature and'period of the annealing before the skin-pass rolling are not restricted to the values of 600C. and 20 minutes given the previous embodiment, the temperature need not be raised to 900C. which is the temperature shown by the prior art.
  • the annealing step is for the purpose of increasing the ducitlity of the material. It need be carried out to the extent that the crystal grain does not become large (larger than the ASTM grain size 7 or so) and that the unevenness of the sheet as caused by the annealing can be leveled by the skin-pass step.
  • the lower limit is to the extent of the recrystallization temperature. It is usually suitable to perform the annealing in a low temperature range of 550C. 650C.
  • the press-forming operation is done without di storting the pattern of the holes formed by the etching on account of the annealing and leveling steps, and hence, any non-conforming of the resultant article, due to the damage of the pattern does not arise at all. Further, since the deflection of the pattern is not caused, the production process of the color TV Braun tubes using these shadow masks is sharply improved.
  • the bending moments can be imparted to the sheet by making use of the distribution of the residual stresses generated by the skin-pass rolling, so that the color shading or deflection on the television picture frame as attributed to the thermal deformation of the shadow mask can be lessened.
  • the shadow mask to which this invention is directed is not restricted in the shape of the holes to being Circular, but the above effects are similarly achieved for a rectangular shape or any other shape.
  • acceptable yield point elongation, the ductility of the sheet steel and acceptable slow rate for aging for purposes of this invention are respectively 1% yield point and less, 15% ductility and more in total strain, and at least more slow rate of aging than that of leveling (at room temperature for 1.5 months to 1% strain).
  • the starting material of the sheet steel is a low carbon steel containing 0.1% or less by weight of carbon and that the thickness of the steel sheet is that suitable for forming shadow masks, i.e., from 0.1 to 0.3
  • a method for manufacturing a shadow mask comprising a first step of annealing a material of low-carbon sheet steel, a second step of thereafter subjecting the annealed sheet steel to skin-pass rolling for a reduction of 0.5 l5% in thickness thereby providing a predetermined thickness, a third step of thereafter forming holes in the sheet steel, and a fourth step of thereafter pressforming the sheet steel into a desired plane.
  • said first step comprises a step of annealing at a low temperature a material of low-carbon sheet steel subjected to cold rolling.
  • said second step comprises a step of subjecting said sheet steel to the skin-pass rolling of the reduction of 0.5 to bring the sheet steel into the predetermined thickness and to give rise to a residual stress distribution which consists of compressions at both surface layer parts of said sheet steel and a tension at a central layer part thereof.
  • said third step comprises a step of perforating said sheet steel by etching by Which the holes are so formed as to be larger on one surface side than on the other surface side, thereby giving rise to a residual stress distribution which consists of a great compression on the smaller hole side and null stress and a tension over from the surface on the larger hole side to said central layer part.
  • a method for manufacturing a shadow mask comprising the step of annealing at a low temperature a material of low-carbon sheet steel subjected to cold roll ing, the step of thereafter subjecting the sheet steel to skin-pass rolling of a reduction of 0.5 15% to thus bring it into a predetermined thickness and give rise to a residual stress distribution which consists of compressions at both surface layer parts of said sheet steel and a tension at a central layer part thereof, the step of thereafter forming holes in said sheet steel by etching wherein said holes are made larger on one surface side than on the other surface side of said sheet steel, thereby giving rise to a residual stress distribution which consists of a great compression on the smaller hole side and null stress and a tension over from the surface on the larger hole side to said central layer part, and the step of thereafter press-forming the sheet steel into a desired curved plane.
  • the sheet steel has a carbon content not more than 0.1% by weight and a thickness of from 0.1 to 0.3 mm.
  • annealing is conducted at 550C. to 650C. for a period of from 10 minutes to 8 hours under an inert gas.
  • the sheet steel has a carbon content of not more than 0.1% and an initial thickness ranging from 0.1 to 0.3 mm; the annealing is conducted from 550 650C. for a period of from 10 minutes to 8 hours under an inert gas; and the holes are formed in the sheet steel by etching.
  • the desired plane formed by press-forming said sheet steel is a curved plane having bending moments exerted thereon which suppress expansion.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US444569A 1973-02-21 1974-02-21 Method for manufacturing a shadow mask Expired - Lifetime US3909928A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP48020167A JPS5244868B2 (ko) 1973-02-21 1973-02-21
JP48075358A JPS5023317A (ko) 1973-07-04 1973-07-04

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US3909928A true US3909928A (en) 1975-10-07

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US (1) US3909928A (ko)
DE (1) DE2408435C3 (ko)
FR (1) FR2218642B1 (ko)
GB (1) GB1464131A (ko)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4094678A (en) * 1976-12-07 1978-06-13 Zenith Radio Corporation Method of making curved color cathode ray tube shadow masks having interregistrable electron beam-passing aperture patterns
US4187443A (en) * 1978-09-08 1980-02-05 Rca Corporation Color picture tube having improved corrugated apertured mask and method of making same
DE2942046A1 (de) * 1978-10-18 1980-04-24 Dainippon Printing Co Ltd Verfahren zur herstellung von stahlstreifenmaterial zur verwendung bei der herstellung einer lochmaske einer braun'schen farbfernsehroehre
DE2945467A1 (de) * 1978-11-15 1980-05-22 Dainippon Printing Co Ltd Lochmaske fuer eine braunsche farbfernsehroehre sowie verfahren zur herstellung derselben
US4210843A (en) * 1979-04-03 1980-07-01 Zenith Radio Corporation Color CRT shadow mask and method of making same
US4528246A (en) * 1982-08-27 1985-07-09 Tokyo Shibaura Denki Kabushiki Kaisha Shadow mask
US4536226A (en) * 1983-04-27 1985-08-20 Kabushiki Kaisha Toshiba Method of manufacturing a shadow mask for a color cathode ray tube
US4616154A (en) * 1983-06-28 1986-10-07 U.S. Philips Corporation Cathode ray tube having an Fe-Co-Cr shadow mask and method of manufacturing such a shadow mask
US20040100638A1 (en) * 2002-11-27 2004-05-27 The Regents Of The University Of California. Correcting surface contour of a non-rigid object through control of surface residual stress

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3519869A (en) * 1967-04-11 1970-07-07 Victor Company Of Japan Shadow mask having apertures progressively tapered from center to periphery
US3676914A (en) * 1970-05-01 1972-07-18 Zenith Radio Corp Manufacture of shadow mask color picture tube
US3707640A (en) * 1970-06-18 1972-12-26 Zenith Radio Corp Shadow mask having double-sized apertures
US3808071A (en) * 1972-04-14 1974-04-30 Zenith Radio Corp Etch-back process
US3809945A (en) * 1973-03-02 1974-05-07 Zenith Radio Corp Shadow mask for color cathode ray tube and method of manufacture thereof

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3376451A (en) * 1966-09-12 1968-04-02 Buckbee Mears Co Shadow mask and magnetic shield unitary construction for color tv picture tubes
US3479546A (en) * 1968-06-11 1969-11-18 Buckbee Mears Co Self-supporting shadow mask for colored tv picture tubes
US3663997A (en) * 1970-09-30 1972-05-23 Rca Corp Method for making a kinescope comprising production and treatment of a temporary mask

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3519869A (en) * 1967-04-11 1970-07-07 Victor Company Of Japan Shadow mask having apertures progressively tapered from center to periphery
US3676914A (en) * 1970-05-01 1972-07-18 Zenith Radio Corp Manufacture of shadow mask color picture tube
US3707640A (en) * 1970-06-18 1972-12-26 Zenith Radio Corp Shadow mask having double-sized apertures
US3808071A (en) * 1972-04-14 1974-04-30 Zenith Radio Corp Etch-back process
US3809945A (en) * 1973-03-02 1974-05-07 Zenith Radio Corp Shadow mask for color cathode ray tube and method of manufacture thereof

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4094678A (en) * 1976-12-07 1978-06-13 Zenith Radio Corporation Method of making curved color cathode ray tube shadow masks having interregistrable electron beam-passing aperture patterns
US4187443A (en) * 1978-09-08 1980-02-05 Rca Corporation Color picture tube having improved corrugated apertured mask and method of making same
DE2942046A1 (de) * 1978-10-18 1980-04-24 Dainippon Printing Co Ltd Verfahren zur herstellung von stahlstreifenmaterial zur verwendung bei der herstellung einer lochmaske einer braun'schen farbfernsehroehre
US4309886A (en) * 1978-10-18 1982-01-12 Nisshin Steel Co., Ltd. Process for producing steel strip material for use in manufacture of shadow mask of Braun tube for color TV
DE2945467A1 (de) * 1978-11-15 1980-05-22 Dainippon Printing Co Ltd Lochmaske fuer eine braunsche farbfernsehroehre sowie verfahren zur herstellung derselben
US4306172A (en) * 1978-11-15 1981-12-15 Nisshin Steel Co., Ltd. Shadow mask of braun tube for color TV and process for manufacturing the same
US4210843A (en) * 1979-04-03 1980-07-01 Zenith Radio Corporation Color CRT shadow mask and method of making same
US4528246A (en) * 1982-08-27 1985-07-09 Tokyo Shibaura Denki Kabushiki Kaisha Shadow mask
US4536226A (en) * 1983-04-27 1985-08-20 Kabushiki Kaisha Toshiba Method of manufacturing a shadow mask for a color cathode ray tube
US4616154A (en) * 1983-06-28 1986-10-07 U.S. Philips Corporation Cathode ray tube having an Fe-Co-Cr shadow mask and method of manufacturing such a shadow mask
US20040100638A1 (en) * 2002-11-27 2004-05-27 The Regents Of The University Of California. Correcting surface contour of a non-rigid object through control of surface residual stress

Also Published As

Publication number Publication date
DE2408435C3 (de) 1982-03-04
GB1464131A (en) 1977-02-09
DE2408435A1 (de) 1974-09-12
DE2408435B2 (de) 1981-07-02
FR2218642A1 (ko) 1974-09-13
FR2218642B1 (ko) 1976-11-26

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