Method and apparatus for shaping thermoplastic sheet material
AssigneeSaint-Gobain Industries
InventorsMaurice Nedelec, Claude Presta, Francois Vitoux
Life of this patent
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Abstract
A method and apparatus are described for bending sheets in the plastic state, such as sheets of glass at their softening temperature, in two directions. The apparatus comprises a first bed of arcuate rods which can be positioned to impart a transverse curvature to the sheet and a second bed of arcuate rods which can be positioned to impart a longitudinal curvature to the sheet. Advantageously the bending is performed in a heated enclosure at a temperature at least equal to that at which the sheet is later tempered.
Claims25
Apparatus for bending to a predetermined curvature a sheet of material in the plastic state, such as a sheet of glass brought to the softening temperature, comprising:
- means for conveying said sheet in a first direction;
- a forming bed comprising a plurality of curved forming rods, said rods having aligned end sections forming respective longitudinal axes and a curved center section extending away from said longitudinal axis;
- means for mounting at least some of said curved rods with their longitudinal axes generally transverse to said first direction and their curved sections inclined at an angle to said first direction, thereby defining a surface that is curved in the direction transverse to said first direction;
- means for mounting the forming rod nearest the upstream side of said forming bed so that an envelope defined by the forming rods is tangential to the surface of said sheet as it enters said forming bed;
- means for mounting said forming rods near the downstream side of said forming bed so that the envelope defined by said rods is curved in the longitudinal direction in which said sheet is moved;
- and
- means for adjusting the position of the rods which define said curved envelope so as to alter the radius of curvature of said envelope in the longitudinal direction, whereby the radius of curvature of said sheet in the longitudinal direction is also altered.
A method for bending and tempering sheets of material in the plastic state, such as a sheet of glass brought to the softening temperature, in which said sheets are heated, bent, and them tempered, said method comprising the steps of:
- heating the sheet to a temperature which is at least equal to the temperature at the start of the tempering step and maintaining said sheet at said temperature for an extended period;
- bending the sheet while the sheet is held at said temperature by moving said sheet through a forming bed comprising a plurality of curved forming rods, said rods having aligned end sections forming respective longitudinal axes and a curved center section, said rods being mounted with their longitudinal axes generally transverse to the direction of movement of said sheets, some of said rods being mounted with their curved sections inclined at an angle to said direction of movement of said sheets and said rods near the downstream end of said forming bed being mounted at different heights with respect to one another, whereby an envelope is defined having a transverse curvature profle and a longitudinal curvature profile that change progressively in the direction of advancement of the sheet;
- and
- tempering the sheet immediately after bending by subjecting it to a uniform blowing action.
Apparatus for bending to a predetermined transverse and longitudinal curvature a sheet of material in the plastic state, such as a sheet of glass brought to softening temperature, said apparatus comprising:
- a series of curved rods which can be positioned to form a curved bed for receiving said sheet, said rods having aligned end sections forming respective axes of rotation of the rods;
- means for holding some of said rods at different angles of inclination to the direction of movement of the sheet to provide a fixed bed having a transverse curvature profile which changes progressively in the direction of advancement of the sheet to a curvature corresponding to said predetermined transverse curvature;
- and
- means for holding said rods near the downstream end of said bed at an approximately constant angle of inclination to the direction of movement of the sheet but at different heights with respect to one another to provide a fixed bed having a longitudinal curvature profile corresponding to said predetermined longitudinal curvature.
Apparatus for bending to a predetermined curvature a sheet of material in the plastic state, such as a sheet of glass brought to the softening temperature, comprising:
- means for conveying said sheet in a first direction;
- a forming bed comprising a plurality of curved forming rods mounted in bearings for rotation about respective axes, each of said rods having a curved center section extending away from its axis of rotation;
- means for mounting some of said curved rods with their axes of rotation generally transverse to said first direction and their curved sections inclined at increasingly greater angles to said first direction, thereby defining an envelope that is curved in the direction transverse to said first direction and increases in curvature toward the downstream side of said forming bed;
- means for mounting the forming rod nearest the upstream side of said forming bed so that said envelope defined by the forming rods is tangential to the surface of said sheet as it enters said forming bed;
- means for mounting said forming rods near the downstream side of said forming bed so that the envelope defined by said rods is curved in the longitudinal direction in which said sheet is moved;
- and
- means for adjusting the position of the rods which define said curved envelope so as to alter the radius of curvature of said envelope in the longitudinal direction, whereby the radius of curvature of said sheet in the longitudinal direction is also altered.
A method for bending and tempering sheets of material in the plastic state, such as a sheet of glass brought to the softening temperature, in which said sheets are heated, bent, and then tempered, said method comprising the steps of:
- heating the sheet to a temperature which is at least equal to the temperature at the start of the tempering step and maintaining said sheet at said temperature for an extended period;
- simultaneously bending the sheet in two directions while the sheet is held at said temperature by moving said sheet through a forming bed comprising a plurality of curved forming rods, each of which is mounted in bearings for rotation about an axis and has a curved center section extending away from said axis of rotation, some of said rods being mounted with their curved sections inclined at an angle to said direction of movement of said sheets, whereby said sheets are curved in the direction transverse to their movement, and some of said rods being mounted at different heights with respect to one another, whereby said sheets are curved in the direction of their movement;
- and
- tempering the sheet immediately after bending by subjecting it to a uniform blowing action.
A method for bending and tempering sheets of material in the plastic state, such as a sheet of glass brought to the softening temperature, in which said sheets are heated, bent, and then tempered, said method comprising the steps of:
- heating the sheet to a temperature which is at least equal to the temperature at the start of the tempering step and maintaining said sheet at said temperature for an extended period;
- bending the sheet under its own weight in two directions while the sheet is held at said temperature by moving said sheet through a forming bed comprising a plurality of curved forming rods, each of which is mounted in bearings for rotation about an axis and has a curved center section extending away from said axis of rotation, some of said rods being mounted with their curved sections inclined at an angle to said direction of movement of said sheets, whereby said sheets are curved in the direction transverse to their movement, and some of said rods being mounted at different heights with respect to one another, whereby said sheets are curved in the direction of their movement;
- and
- tempering the sheet immediately after bending by subjecting it to a uniform blowing action.
A method for bending and tempering sheets of material in the plastic state, such as a sheet of glass brought to the softening temperature, in which said sheets are heated, bent, and then tempered, said method comprising the steps of:
- heating the sheet to a temperature which is at least equal to the temperature at the start of the tempering step and maintaining said sheet at said temperature for an extended period;
- bending the entire sheet simultaneously to increasingly greater curvature while the sheet is held at said temperature by moving said sheet through a forming bed comprising a plurality of curved forming rods, each of which is mounted in bearings for rotation about an axis and has a curved center section extending away from said axis of rotation, some of said rods being mounted with their curved sections inclined at an angle to said direction of movement of said sheets, whereby said sheets are curved in the direction transverse to their movement, and some of said rods being mounted at different heights with respect to one another, whereby said sheets are curved in the direction of their movement;
- and
- tempering the sheet immediately after bending by subjecting it to a uniform blowing action. PG,42
Dependencies are inferred from the claim text.