US3854920A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High temperature bending
Assignee: Pilkington Automotive Ltd
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Filing: 1973-10-11
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Granted: 1974-12-17
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Expires: 1993-10-11
Abstract
Abstract Bent glass sheets are produced with avoidance of ''''spring back'''' on cooling, by applying complementary bending surfaces to a heated flat glass sheet, which surfaces are at substantially the bending temperature of the glass, and maintaining the surfaces closed on the sheet for a time sufficient to permit decay of thermal inhomogeneities and bending stresses.
Inventors
- 👤 S Kay
- 👤 J Pickard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:05
CPC Classifications
C; C03; C03B; C03B23/00; C03B23/02; C03B23/023; C03B23/03; C03B23/031
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
172 words
A method of manufacturing a curved glass sheet which comprises the steps of: a. heating a glass sheet substantially to a selected temperature within the bending temperature range of the glass; b. heating complementary bending surfaces to said selected bending temperature; c. applying the bending surfaces while heated to the temperature of step (b) to the opposite side surfaces of the glass sheet heated to the temperature of step (a) to conform the sheet to the curvature of said bending surfaces; d. continuing step (c) for a time sufficient to consolidate the shape of the sheet at said curvature and to establish a thermal condition of the sheet at the temperature of said bending surfaces to assure close retention of said curvature on withdrawal of thE bending surfaces from both surfaces of the glass sheet; e. withdrawing said bending surfaces from both surfaces of the glass sheet at the end of said time, and then f. uniformly cooling both surfaces of the curved sheet from the thermal condition established by step (d).
Claim 2
Independent Claim
172 words
A method of manufacturing a curved glass sheet which comprises the steps of: a. heating a glass sheet substantially to a selected temperature within the bending temperature range of the glass; b. heating complementary bending surfaces to said selected bending temperature; c. applying the bending surfaces while heated to the temperature of step (b) to the opposite side surfaces of the glass sheet heated to the temperature of step (a) to conform the sheet to the curvature of said bending surfaces; d. continuing step (c) for a time sufficient to consolidate the shape of the sheet at said curvature and to establish a thermal condition of the sheet at the temperature of said bending surfaces to assure close retention of said curvature on withdrawal of thE bending surfaces from both surfaces of the glass sheet; e. withdrawing said bending surfaces from both surfaces of the glass sheet at the end of said time, and then f. uniformly cooling both surfaces of the curved sheet from the thermal condition established by step (d).
Claim 3
Dependent Claim
23 words
A method according to claim 1, including engaging at least one of the bending surfaces with marginal areas only of the glass sheet.
Claim 4
Dependent Claim
40 words
A method according to claim 1, including employing bending surfaces of which each bending surface has an arm projected on to the plane of the glass sheet which is at least equal to the surface area of said glass sheet.
Claim 5
Dependent Claim
28 words
A method according to claim 1, including maintaining the bending surfaces at said selected bending temperature by periodically heating respective bending dies on which said surfaces are provided.
Claim 6
Dependent Claim
22 words
A method according to claim 1, wherein the glass sheet is quenched in step (f) to provide a toughened, curved glass sheet.
Claim 7
Dependent Claim
325 words
Apparatus for bending glass sheets, comprising: a. furnace means including a first chamber for establishing an environment to heat a glass sheet passing therethrough to a selected temperature within the bending temperature range of the glass, said first chamber having entrance and exit openings; b. bending means including a second chamber aligned with said first chamber and cooling means aligned with said second chamber; c. conveyor means for moving a procession of glass sheets through said first chamber whereby each glass sheet emerges from said first chamber in a heated condition such that its average temperature is near said selected bending temperature; d. said bending means including a pair of bending dies housed within said second chamber and having complementary bending surfaces of the desired curvature to be imparted to each of said glass sheets, each bending die comprising a base of a castable refractory having a high content of silica or alumina, which base is coated with an organo-platinum paste which is fired and polished to present a smooth bending surface, and said second chamber having entrance and exit openings and being aligned with said exit opening of the first chamber to receive the emergent heated glass sheets in succession; e. means for maintaining said bending surfaces at said selected bending temperature; f. means for advancing and retracting both of said bending dies to engage opposite sides of each glass sheet and impart thereto said desired curvature and for maintaining said bending surfaces in contact with the opposite sides of a sheet for a time sufficient to consolidate the shape of the sheet at said curvature and to establish a thermal condition of the sheet at the temperature of said bending surfaces to assure close retention of said curvature on withdrawal of the bending surfaces from both surfaces of the glass sheet; and g. said cooling means including means for cooling both surfaces of each curved glass upon its emergence from said second chamber.
Claim 8
Dependent Claim
325 words
Apparatus for bending glass sheets, comprising: a. furnace means including a first chamber for establishing an environment to heat a glass sheet passing therethrough to a selected temperature within the bending temperature range of the glass, said first chamber having entrance and exit openings; b. bending means including a second chamber aligned with said first chamber and cooling means aligned with said second chamber; c. conveyor means for moving a procession of glass sheets through said first chamber whereby each glass sheet emerges from said first chamber in a heated condition such that its average temperature is near said selected bending temperature; d. said bending means including a pair of bending dies housed within said second chamber and having complementary bending surfaces of the desired curvature to be imparted to each of said glass sheets, each bending die comprising a base of a castable refractory having a high content of silica or alumina, which base is coated with an organo-platinum paste which is fired and polished to present a smooth bending surface, and said second chamber having entrance and exit openings and being aligned with said exit opening of the first chamber to receive the emergent heated glass sheets in succession; e. means for maintaining said bending surfaces at said selected bending temperature; f. means for advancing and retracting both of said bending dies to engage opposite sides of each glass sheet and impart thereto said desired curvature and for maintaining said bending surfaces in contact with the opposite sides of a sheet for a time sufficient to consolidate the shape of the sheet at said curvature and to establish a thermal condition of the sheet at the temperature of said bending surfaces to assure close retention of said curvature on withdrawal of the bending surfaces from both surfaces of the glass sheet; and g. said cooling means including means for cooling both surfaces of each curved glass upon its emergence from said second chamber.
Claim 9
Dependent Claim
29 words
Apparatus according to claim 6, in which the said means for maintaining the die surfaces at said selected bending temperature comprise heating means located internally of the respective dies.
Claim 10
Dependent Claim
36 words
Apparatus according to claim 6, in which the dies are horizontally acting, and in which sheet supporting means are provided for supporting a glass sheet to be bent in a substantially vertical plane between the dies.
Claim 11
Dependent Claim
16 words
Apparatus according to claim 6, in which said furnace means comprises a series of heating chambers.
Claim 12
Dependent Claim
37 words
Apparatus according to claim 6, wherein said bending means includes a further pair of complementary bending dies to perform an initial bending of each heated glass sheet prior to final bending by the first mentioned bending dies.
Claim 13
Dependent Claim
21 words
Apparatus according to claim 6, wherein said means for cooling consists of a quenching station for toughening each curved glass sheet.
Claim 14
Independent Claim
254 words
A method of manufacturing a curved glass sheet which comprises the steps of: a. heating a glass sheet at one location to an inherent thermally inhomogeneous condition in which its average temperature is a selected temperature within the bending temperature range of the glass, b. heating complementary bending surfaces at a second location to said selected temperature, c. removing the glass sheet from said one location to said second location and applying the bending surfaces while heated to the temperature of step (b) to the opposite side surfaces of the glass sheet heated to the condition of inherent thermal inhomogeneity of step (a) to conform the sheet to the curvature of said bending surfaces, d. continuing step (c) for a time sufficient to establish thermal homogeneity in the glass in which there is equality of the temperatures of the bending surfaces and the glass sheet being bent and the temperature of the glass sheet is within said selected bending temperature range throughout the thickness dimension of the glass sheet and of uniform temperature across both surfaces of the glass sheet, e. withdrawing said bending surfaces from both surfaces of the glass sheet when said thermal homogeneity in the glass sheet is established and removing the glass sheet from said second location while said condition of thermal homogeneity prevails for assuring close retention of said curvature imparted to the glass sheet by said bending surfaces, and f. uniformly cooling both surfaces of the curved sheet from the condition of thermal homogeneity established by step (d).
Claim 15
Independent Claim
254 words
A method of manufacturing a curved glass sheet which comprises the steps of: a. heating a glass sheet at one location to an inherent thermally inhomogeneous condition in which its average temperature is a selected temperature within the bending temperature range of the glass, b. heating complementary bending surfaces at a second location to said selected temperature, c. removing the glass sheet from said one location to said second location and applying the bending surfaces while heated to the temperature of step (b) to the opposite side surfaces of the glass sheet heated to the condition of inherent thermal inhomogeneity of step (a) to conform the sheet to the curvature of said bending surfaces, d. continuing step (c) for a time sufficient to establish thermal homogeneity in the glass in which there is equality of the temperatures of the bending surfaces and the glass sheet being bent and the temperature of the glass sheet is within said selected bending temperature range throughout the thickness dimension of the glass sheet and of uniform temperature across both surfaces of the glass sheet, e. withdrawing said bending surfaces from both surfaces of the glass sheet when said thermal homogeneity in the glass sheet is established and removing the glass sheet from said second location while said condition of thermal homogeneity prevails for assuring close retention of said curvature imparted to the glass sheet by said bending surfaces, and f. uniformly cooling both surfaces of the curved sheet from the condition of thermal homogeneity established by step (d).
Claim 16
Independent Claim
125 words
The method of eliminating spring back in any significant degree during the manufacture of curved glass sheets, which comprises the steps of: a. advancing a pair of complementary bending surfaces into engagement with the opposite surfaces of a heated glass sheet for conforming the heated glass sheet to the curvature of said bending surfaces; b. heating said bending surfaces for maintaining them at a temperature during step (a) which is the same as the temperature of the heated glass sheet; c. maintaining said bending surfaces against said opposite surfaces of the glass sheet for a time sufficient to eliminate spring back; and then d. retracting said bending surfaces simultaneously from the opposite surfaces of said glass sheet; and then e. uniformly cooling said glass sheet.
Claim 17
Independent Claim
125 words
The method of eliminating spring back in any significant degree during the manufacture of curved glass sheets, which comprises the steps of: a. advancing a pair of complementary bending surfaces into engagement with the opposite surfaces of a heated glass sheet for conforming the heated glass sheet to the curvature of said bending surfaces; b. heating said bending surfaces for maintaining them at a temperature during step (a) which is the same as the temperature of the heated glass sheet; c. maintaining said bending surfaces against said opposite surfaces of the glass sheet for a time sufficient to eliminate spring back; and then d. retracting said bending surfaces simultaneously from the opposite surfaces of said glass sheet; and then e. uniformly cooling said glass sheet.
Claim 18
Dependent Claim
25 words
The method as defined in claim 13 wherein the glass sheet is heated to a temperature in the lower region of the bending temperature range.
Claim 19
Independent Claim
132 words
The method of producing a curved glass sheet while eliminating spring back in any significant degree, the glass of said sheet having a bending temperature range lying between a lower limit and an upper limit, said method comprising the steps of: a. heating the glass sheet to a low temperature above but near said lower limit; b. heating complementary bending surfaces to the low temperature to which the glass sheet is heated in step (a); c. applying the bending surfaces to the opposite side surfaces of the heated glass sheet to conform the glass sheet to the curvature of said bending surfaces; d. maintaining said bending surfaces against said opposite side surfaces of the glass sheet for a time sufficient to eliminate spring back; and then e. uniformly cooling said glass sheet.
Claim 20
Independent Claim
132 words
The method of producing a curved glass sheet while eliminating spring back in any significant degree, the glass of said sheet having a bending temperature range lying between a lower limit and an upper limit, said method comprising the steps of: a. heating the glass sheet to a low temperature above but near said lower limit; b. heating complementary bending surfaces to the low temperature to which the glass sheet is heated in step (a); c. applying the bending surfaces to the opposite side surfaces of the heated glass sheet to conform the glass sheet to the curvature of said bending surfaces; d. maintaining said bending surfaces against said opposite side surfaces of the glass sheet for a time sufficient to eliminate spring back; and then e. uniformly cooling said glass sheet.
Claim 21
Dependent Claim
103 words
A method according to claim 1, wherein the step of applying heated bending surfaces to the opposite side surfaces of the glass sheet includes enforcing movement of the bending surfaces from a position of first contact with the surfaces of the glass sheet to a position of complete application of the surfaces against the glass sheet surfaces in a time period related to glass thickness and longer for thicker glass than for thinner glass, such that residual bending stresses in the glass at the end of that period subsequently relax during the time of continuing application of the bending surfaces to the sheet.
Claim 22
Independent Claim
188 words
The method of producing a curved sheet of soda-lime-silica glass while eliminating spRing back to any significant degree, the glass sheet having a bending temperature range lying between a lower limit of 550*C and an upper limit of 680*C, said method comprising the steps of: a. heating the glass sheet to a low temperature above but near said lower limit of 550*C; b. heating complementary bending surfaces to the low temperature to which the glass sheet is heated in step (a); c. enforcing movement of the bending surfaces from a position of first contact with the surfaces of the glass sheet to a position of complete application of the surfaces against the glass sheet surfaces now curved to the curvature of said bending surfaces in a time period so related to glass thickness as to minimise residual bending stresses in the glass at the end of that period. d. maintaining said bending surfaces against said glass sheet surfaces for a time sufficient to eliminate spring-back; e. withdrawing said bending surfaces from the opposite surfaces of the curved glass sheet; and then f. uniformly cooling said curved glass sheet.
Claim 23
Independent Claim
188 words
The method of producing a curved sheet of soda-lime-silica glass while eliminating spRing back to any significant degree, the glass sheet having a bending temperature range lying between a lower limit of 550*C and an upper limit of 680*C, said method comprising the steps of: a. heating the glass sheet to a low temperature above but near said lower limit of 550*C; b. heating complementary bending surfaces to the low temperature to which the glass sheet is heated in step (a); c. enforcing movement of the bending surfaces from a position of first contact with the surfaces of the glass sheet to a position of complete application of the surfaces against the glass sheet surfaces now curved to the curvature of said bending surfaces in a time period so related to glass thickness as to minimise residual bending stresses in the glass at the end of that period. d. maintaining said bending surfaces against said glass sheet surfaces for a time sufficient to eliminate spring-back; e. withdrawing said bending surfaces from the opposite surfaces of the curved glass sheet; and then f. uniformly cooling said curved glass sheet.
Claim 24
Independent Claim
181 words
A method of producing a curved sheet of soda-lime-silica glass while eliminating spring back to any significant degree, the glass sheet having a bending temperature range lying between a lower limit of 570*C and an upper limit of 600*C, said method comprising the steps of: a. heating the glass sheet to a temperature in that range; b. heating complementary bending surfaces to the temperature to which the glass sheet is heated in step (a); c. enforcing movement of the bending surfaces from a position of first contact with the surfaces of the glass sheet to a position of complete application of the surfaces against the glass sheet surfaces now curved to the curvature of said bending surfaces in a time period so related to glass thickness as to minimise residual bending stresses in the glass at the end of that period; d. maintaining said bending surfaces against said glass sheet surfaces for a time sufficient to eliminate spring-back; e. withdrawing said bending surfaces from the opposite surfaces of the curved glass sheet; and then f. uniformly cooling said curved glass sheet.
Claim 25
Independent Claim
181 words
A method of producing a curved sheet of soda-lime-silica glass while eliminating spring back to any significant degree, the glass sheet having a bending temperature range lying between a lower limit of 570*C and an upper limit of 600*C, said method comprising the steps of: a. heating the glass sheet to a temperature in that range; b. heating complementary bending surfaces to the temperature to which the glass sheet is heated in step (a); c. enforcing movement of the bending surfaces from a position of first contact with the surfaces of the glass sheet to a position of complete application of the surfaces against the glass sheet surfaces now curved to the curvature of said bending surfaces in a time period so related to glass thickness as to minimise residual bending stresses in the glass at the end of that period; d. maintaining said bending surfaces against said glass sheet surfaces for a time sufficient to eliminate spring-back; e. withdrawing said bending surfaces from the opposite surfaces of the curved glass sheet; and then f. uniformly cooling said curved glass sheet.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-16 | 1978-06-17 | 1978-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-16 | 1982-06-17 | 1982-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-16 | 1986-06-17 | 1986-12-17 | $7700.00 | Window Closed / Lapsed |