Electrically activated flexible press for shaping heat softenable sheet material

The present invention provides a shaping mold for shaping heat softenable sheet material which includes a flexible rail having a sheet shaping surface to support a marginal edge portion of a sheet to be shaped and a plurality of controllable actuators secured to the rail and capable of deforming the rail to provide its surface with configurations each having a desired elevational contour. In one particular embodiment of the invention, the shaping rail is a shaping ring having a peripheral configuration which provides generally continuous support about the marginal edge portion of the sheet. A controller is used to control each actuator and deform the sheet shaping surface of the ring from a first configuration having a generally flat elevational contour to a second configuration having an elevational contour that generally corresponds to the final desired contour of the marginal edge portion of the sheet.

BACKGROUND OF THE INVENTION 
This invention relates to shaping heat softened sheet material, and in 
particular to shaping heat softened glass sheets between an upper mold and 
a lower flexible ring mold. 
Shaped and tempered glass sheets are widely used as windows in vehicles 
such as automobiles and the like. To fabricate these windows, flat glass 
sheets must be shaped to precisely defined curvatures dictated by the 
shape and outline of the window frame openings in the vehicle. It is 
important that the windows meet stringent optical requirements and be free 
of optical defects that would tend to interfere with clear viewing through 
the window. 
Commercial production of shaped glass sheets commonly includes the steps of 
serially conveying the glass sheets through a tunnel-type furnace where 
they are heated to their heat deformation temperature and thereafter 
conveying the heat softened sheets into a shaping station where they are 
shaped by pressing each sheet between a pair of vertically aligned, upper 
and lower shaping molds. After shaping, the molds separate with the shaped 
glass sheet remaining secured to the upper mold by vacuum. A transfer ring 
having an outline and shape conforming to the desired curvature of the 
glass sheet slightly inboard of its perimeter, moves beneath the upper 
mold which thereafter releases the vacuum and deposits the shaped glass 
sheet on the ring. The ring then transfers the shaped glass sheet into a 
cooling station for controlled cooling. 
The lower mold in such sheet shaping arrangement may include a rigid 
shaping ring as disclosed in U.S. Pat. No. 4,496,386 to Hymore et al. or a 
flexible shaping ring as disclosed in U.S. Pat. No. 4,830,650 to Kelly and 
5,401,286 to Goolsbay et al. During shaping, the lower mold moves upward 
from a position below the conveying surface of the conveying rolls to lift 
the glass sheet off the rolls and into engagement with the upper mold. 
Each of these shaping arrangements has certain shortcomings. When using a 
rigid ring, since the ring has an elevational configuration generally 
corresponding to the final desired peripheral shape of the glass sheet, 
the ring does not simultaneously contact the entire marginal edge of the 
glass sheet as it initially lifts the sheet off the conveyor rolls. 
Rather, the rigid ring progressively engages the marginal edge with the 
higher points of the ring contacting the ring first. As a result, the 
glass may slide along the sheet engaging surface of the ring as the glass 
is shaped. When using a flexible ring mold, the ring has a flat 
configuration when it initially engages the glass sheet so that the entire 
marginal edge of the sheet is contacted simultaneously by the ring as the 
ring lifts the sheet off the conveyor rolls. However, as the glass is 
pressed against the upper mold, the pressure applied by the flexible ring 
depends on the member used to maintain the ring in an undeformed 
configuration. For example, in a ring as disclosed in U.S. Pat. No. 
4,830,650, the pressing force depends on the spring constants of the 
springs which support the flexible ring. In addition, the deformation of 
the glass sheet is controlled by the pressing action of the flexible ring 
against the upper mold. 
It would be advantageous to provide an arrangement whereby the lower mold 
engages marginal edge portion of a glass sheet to be shaped along at least 
a portion of the periphery of the glass sheet and controllably deforms to 
shape and subsequently press the marginal edge of the sheet against an 
upper shaping mold to ensure that the configuration of the pressed 
marginal edge portion conforms to the shape of the upper mold. 
SUMMARY OF THE INVENTION 
The present invention provides a shaping mold for shaping heat softenable 
sheet material which includes a flexible rail having a sheet shaping 
surface to support a marginal edge portion of a sheet to be shaped and a 
plurality of controllable actuators secured to the rail and capable of 
deforming the rail to provide its surface with configurations each having 
a desired elevational contour. In one particular embodiment of the 
invention, the shaping rail is a shaping ring having a peripheral 
configuration which provides generally continuous support about the 
marginal edge portion of said sheet. A controller is used to control each 
actuator and deform the sheet shaping surface of the ring from a first 
configuration having a generally flat elevational contour to a second 
configuration having an elevational contour that generally corresponds to 
the final desired contour of the marginal edge portion of the sheet. 
The present invention also provides an apparatus for shaping heat softened 
sheet material including an upper mold, lower mold, transfer arrangement 
and actuators. The upper mold has a sheet shaping surface generally 
corresponding to a final desired contour of a sheet to be shaped. The 
lower mold has shaping rail with a flexible sheet engaging surface 
vertically aligned below the upper mold. The transfer arrangement 
transfers the sheet onto the shaping rail such that the sheet engaging 
surface of the shaping rail supports selected marginal edge portions of 
the sheet. The actuators are connected to the shaping rail and vertically 
reciprocate portions of the rail to controllably deform the sheet engaging 
surface of the lower mold and press the selected marginal edge portions of 
the sheet against corresponding portions of the sheet shaping surface of 
the upper mold. In one particular embodiment of the invention, the shaping 
rail is a peripheral shaping ring vertically aligned below the upper mold. 
The ring has a sheet engaging surface that supports the sheet about its 
periphery. 
The present invention also provides a method of shaping heat softened sheet 
material which includes the steps of securing a plurality of actuators at 
selected positions along a shaping rail having a flexible sheet engaging 
surface, engaging selected marginal edge portions of a sheet to be shaped 
with the sheet engaging surface, moving the shaping rail and sheet toward 
an upper shaping mold having a contoured shaping surface generally 
corresponding to a final desired shape of the sheet, controlling the 
actuators to provide the sheet engaging surface of the rail with a 
generally flat configuration during the engaging step and alter the sheet 
engaging surface of the rail during at least a portion of the moving step 
from the flat configuration to a configuration having a curved elevational 
contour that generally conforms to a desired shape of the marginal edge 
portions of said sheet, and pressing the sheet against the upper mold 
sheet shaping surface. In one particular embodiment of the invention, the 
shaping rail is a shaping ring which extends around the periphery of the 
sheet to support and shape the entire marginal edge portion of the sheet.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention is taught in conjunction with its use in shaping heat 
softened glass sheets, but it is understood that the invention may be used 
in shaping any type of heat softened sheet material shaping arrangement. 
Referring to FIG. 1, an apparatus for heating and shaping sheets of heat 
softened materials, such as glass, includes a furnace 12 through which 
glass sheets G are serially conveyed from a loading station (not shown) to 
heat each sheet to its deformation temperature, a shaping station 14 to 
shape the glass sheets, a cooling station 16 for cooling the shaped 
sheets, and an unloading zone (not shown) beyond the cooling station 16. 
Although not limiting in the present invention, the loading and unloading 
zones, furnace 12, shaping station 14 and cooling station 16 are aligned 
in end-to-end relation. A sheet transfer means 18 located at the cooling 
station 16 transfers the shaped glass sheet G between the shaping station 
14 and cooling station 16. 
The furnace 12 includes a horizontal conveyor 20 with longitudinally 
spaced, transversely extending conveyor rolls 22 that define a path of 
travel which extends through the furnace 12. The rolls 22 are arranged in 
sections and their rotational speed is controlled through clutches (not 
shown) so that the speed of each conveyor section may be controlled and 
synchronized in any convenient manner. 
The shaping station 14 includes a series of spaced apart, donut shaped 
support rolls 24, an upper shaping mold 26 and a lower shaping mold 28, 
which is the subject of the present invention. Rolls 24 support the heat 
softened glass sheet G as it exits the furnace 12 and enters the shaping 
station 14. If desired, rolls 24 may be replaced with rolls that provide 
continuous transverse support of the sheet G within lower shaping mold 28. 
Although not limiting in the present invention, the upper mold 26 is a 
vacuum mold, e.g. as disclosed in U.S. Pat. No. 4,579,577. The shaping 
surface 30 of the mold 26 generally conforms to the final desired shape of 
the glass sheet G. If desired, surface 30 may be covered with a heat 
resistant fabric (not shown), e.g. fiber glass or stainless steel cloth. 
With continued reference to FIG. 1, the upper vacuum mold 26, which 
communicates with a vacuum source (not shown) through an evacuation pipe 
32 and suitable valve means (not shown), is connected through upper 
vertical guide rods 34 to a support frame (not shown) and is vertically 
moveable relative to the frame via a piston arrangement 36. The evacuation 
pipe 32 may be connected through a suitable valve arrangement to a source 
of pressurized air (not shown) which may be used to help separate the 
shaped sheet G from the mold 26. 
The lower mold 28 includes a flexible shaping member 38 supported on a 
drive plate 40 by a plurality of actuators 42 which change its elevational 
contour. In the particular embodiment of the invention illustrated in 
FIGS. 1 and 2, the flexible member 38 is a deformable pressing ring having 
a peripheral outline that generally corresponds to the outline of the 
flat, heat softened glass sheet G prior to shaping. Unlike some bending 
rings which include fixed, rigid shaping surfaces that progressively 
contact a glass sheet to be shaped or rotate upward to engage and form the 
glass sheet, the sheet engaging surface 44 of the flexible ring 38 is 
altered by the actuators 42 during the sheet shaping operation to change 
the elevational contour from a first configuration to a second 
configuration. In particular, actuators 42 deform the ring 38 from a 
generally flat configuration when the ring 38 is positioned below the 
glass sheet G prior to shaping, to a curved configuration generally 
corresponding to the peripheral curvature of the upper mold 26 after the 
flexible ring 38 engages the marginal edge portion, 46 of a heat softened 
glass sheet G and presses the Sheet G against mold 26, as will be 
discussed later in more detail. In one particular embodiment of the 
invention, flexible ring 38 includes a flexible support 48 covered with a 
heat resistant cover 50. In the particular embodiment of the invention 
shown in FIG. 2, the heat resistant cover 50 is an insulating board 
secured to a flexible support 48 in a manner such that if required, as the 
ring 38 flexes during shaping, the support 48 and cover 50 may slide 
relative to each other. The combination of support 48 and cover 50 should 
be sufficiently rigid to support the heat softened glass sheet G as it is 
engaged by the lower mold 28, but also sufficiently flexible to deform and 
conform to the configuration of a corresponding portion of the upper is 
mold 26, as will be discussed later. In one particular embodiment of the 
invention, cover 50 is 0.125 inch (3.18 mm) thick Spauldite.RTM. ARK-2 
aramid laminate available from Spaulding Fibre Co., Inc., New York and 
support 48 is 0.030 inch (0.76 mm) thick spring steel. If desired, 
additional heat resistant materials, such as fiberglass or metal press 
cloth (not shown), may be used to cover the ring 38. As an alternative, 
the cover 50 may be replaced with an insulating fabric. For example, the 
flexible ring 38 of lower mold 28 may include a 0.040 inch (1.02 mm) thick 
spring steel as support 48 with a NOR-FAB 1200 series sleeving as cover 
50, available from Norfab Corp., Pennsylvania, secured to the upper 
surface of the support 48. 
Each actuator 42 is an electrically controlled motor 52 that vertically 
reciprocates a rod 54 through a drive arrangement (not shown) such as, but 
not limited to a worm gear or ballscrew drive arrangement. The rod 54 is 
coupled to the lower surface 56 of flexible ring 38 using a connector 
arrangement 58 of a type that preferably allows the ring 38 to change its 
orientation, i.e. pivot and rotate along its transverse and longitudinal 
axes, e.g. a clevis, spring, ball and socket, universal joint or other 
compliant connector, such that the ring 38 may generally conform to the 
curvature of a corresponding peripheral portion of the upper mold 26. 
Although not limiting in the present invention, the connector arrangement 
58 is preferably located outboard of the peripheral edge 60 of the glass 
sheet G, as shown in FIG. 2, so that as the glass sheet G is pressed 
against surface 30 of upper mold 26, as will be discussed later in more 
detail, and the force applied by the flexible ring 38 will be concentrated 
along the edge 60. In this manner, any marking of the glass sheet G along 
the marginal edge portion 46 due to contact with surface 44 of the 
flexible ring 38 will be minimized. In addition, although not limiting in 
the present invention, in the particular embodiment illustrated in FIGS. 
2-6, each actuator 42 is secured to the drive plate 40 via a pinned 
connection 62 that allows the actuator 42 to rotate during the pressing 
and shaping operation, as will be discussed later in more detail. The 
length of the rod 54 for each actuator 42 depends on the final desired 
shape of the glass sheet G. In particular, the greater the bend in the 
glass sheet G, the more the actuator 42 must lift the marginal edge 
portion 46 of the glass sheet G to engage the surface 30 of upper mold 26. 
It should be appreciated that actuators 42 having different stroke lengths 
may be used at various positions along the flexible ring 38. 
Each of the actuators 42 is connected to a controller 64 which controls the 
stroke, i.e. the amount of vertical movement, of each rod 54 via motors 
52, the speed of the stroke and the pressure applied by each actuator 42 
to shape the glass in a desired sequence, as will be discussed later in 
more detail. Since each actuator 42 is individually controlled by 
controller 64, stroke speed and distance and the applied pressure may be 
varied from actuator to actuator as well as varied for a particular 
actuator during the shaping and pressing operation. Although not limiting 
in the present invention, it is expected that each actuator 42 will be 
capable of vertically reciprocating rod 54 at a speed of at least about 5 
inches per second (12.7 cm per second), preferably at least about 10 
inches per second (25.4 cm per second), and applying a force of at least 
about 10 pounds (44.5 Newtons). One type of actuator 42 that may be used 
is an electrically driven linear actuator available from Parker Hannifin 
Corp., Rohnert Park, Calif., which includes a Parker Actuator 
ETB50-B021 -CCA100-A Ballscrew driven actuator, a Parker Compumotor 
BLHX75BN servo drive and a Parker Compumotor ML3450B-10 motor. 
The number and spacing of the actuators 42 depend on the final desired 
configuration of the sheet to be shaped and the amount of control over the 
deformation of the flexible ring 38 that is required. It is expected that 
the flexible ring 38 would be sufficiently rigid between adjacent 
actuators 42 so that any sag in the flexible ring 38 between adjacent 
actuators 42 would be minimal. However, if desired, additional deformable 
supports, for example as disclosed in U.S. Pat. No. 4,830,650, may be 
positioned between actuators 42 to provide any supplemental support to the 
ring 38. 
It should be appreciated that although the preferred actuator includes an 
electrically controlled linear actuator, other types of drive systems may 
be used, e.g. pneumatic or hydraulic cylinders. However, these later types 
of systems are not as responsive as an electric drive arrangement. In 
particular, an electrically driven linear actuator provides superior speed 
and more precise control over the movement of the rods 54. 
Drive plate 40 is secured to an elevator means, which is shown in FIG. 1 as 
lifting cylinder 66, to vertically reciprocate lower mold 28 from an 
initial position, wherein the flexible ring 38 is positioned below the 
support rolls 24 (shown only in FIG. 1) in the shaping station 14 as shown 
in FIG. 3, to a position above the support rolls 24 wherein the glass 
sheet G is lifted off the rolls 24 by flexible ring 38 as shown in FIG. 4, 
as will be discussed later in more detail. Although not required, it is 
preferred that when positioned below rolls 24, flexible ring 38 has a 
generally flat configuration. Depending on the mode of operation, cylinder 
66 may raise drive plate 40 to lift the glass sheet G to a position in 
close proximity to the shaping surface 30 of upper mold 26 or may lift the 
sheet G such that portions of the sheet G which are unsupported by the 
flexible ring 38 contact the surface 30, as will be discussed later in 
more detail. 
If desired, to prevent the ring 38 from deforming during its initial upward 
movement, such as rotation of the ring 38 as it engages and lifts the 
glass sheet G, lower mold 28 may be provided with an assembly (not shown) 
as disclosed in U.S. Pat. No. 5,401,286, which includes a plurality of 
posts which support ring 38 during the initial lifting of the glass sheet 
G and prevent undesired deformation. 
Although not limiting in the present invention, in the particular 
embodiment illustrated in FIG. 1, sheet transfer means 18 includes a 
tempering ring 68 to transfer the shaped glass sheet G between the shaping 
station 14 and cooling station 16. It should be appreciated that other 
sheet transfer arrangements well known in the art may be used to remove 
the shaped sheet from the shaping station 14 and into the cooling station 
16, e.g. as disclosed in U.S. Pat. No. 5,286,271 to Rueter et al. 
Referring to FIGS. 3-6, in operation the glass sheet G is conveyed through 
the furnace 12 to heat the sheet G to its heat softening temperature. 
Sensor 70 senses the position of the glass sheet G and sends this 
information to controller 64 which controls the sheet shaping operation by 
initially controlling the conveying rates of rolls 22 in furnace 12 and 
rolls 24 in shaping station 14. It should be appreciated that if desired, 
a separate controller (not shown) may be used to control the conveying 
rates of rolls 22 and 24. As the glass sheet G exits the furnace 12 and is 
conveyed to shaping station 14, the flexible ring 38 of the lower mold 28 
is positioned below the upper conveying surface of support rolls 24 so 
that the glass sheet G may be conveyed into the shaping station 14 on the 
rolls 24 without interference. Furthermore, actuators 42 are adjusted so 
that flexible ring 38 has a flat configuration when positioned below rolls 
24. When the glass sheet G is in proper position between the upper mold 26 
and the lower mold 28, the glass sheet G is transferred from the rolls 24 
to the lower mold 28. In the particular embodiment of the invention 
illustrated in FIGS. 3-6, this transfer is accomplished by activating 
cylinder 66 (shown only in FIG. 1) to move lower mold 28 upward from its 
initial position below rolls 24, as shown in FIG. 3, to a raised position 
to contact the marginal edge portion 46 of the glass sheet G with flexible 
ring 38 and lift the glass sheet G off rolls 24, as shown in FIG. 4. Since 
actuators 42 shape the ring 38 to initially provide a flat sheet engaging 
surface 44, the ring 38 will simultaneously engage the entire marginal 
edge portion 46 of the sheet G. It should be appreciated that this 
transfer may also be accomplished by lowering rolls 24 to a position below 
ring 38, in any convenient manner known in the art, to deposit the glass 
sheet onto the lower mold 28. 
After lifting the glass sheet G, cylinder 66 continues to move mold 28 
upward to position the sheet G in close proximity to but spaced from the 
sheet shaping surface 30 of the upper mold 26, as shown in FIG. 4. Next, 
actuators 42 are individually energized by controller 64 to raise and 
press marginal edge portions 46 of the sheet G against corresponding 
portions of shaping surface 30. More specifically, in a predetermined 
sequence, actuators 42 drive rods 54 upward to alter the elevational 
contour of sheet engaging surface 44 by progressively deforming 
corresponding portions of the flexible ring 38. For example, as 
illustrated in the particular embodiment shown in FIGS. 5 and 6, all the 
actuators 42 lift the marginal edge portion 46 of the sheet G, with the 
actuators 42 supporting the central marginal edge portions of the sheet G, 
i.e. the actuators furthest to the left in FIG. 5, pressing the supported 
marginal edge portion 46 against surface 30 of upper mold 26. The 
remaining actuators 42 continue to lift the sheet G so that the marginal 
edge portion 46 is progressively pressed against the surface 30 (from left 
to right as viewed in FIGS. 5 and 6) to shape the sheet G. Connectors 58 
at the ends of rods 54 of the actuators 42 and pinned lower connections 62 
of the actuators 42 allow each actuator 42 to rotate as required and the 
flexible ring 38 to pivot and deform so that the sheet engaging surface 44 
may conform to a configuration that generally compliments the 
corresponding peripheral portion of the mold 26. Vacuum is drawn along 
surface 30 during the pressing operation to further shape the interior 
portions of the glass sheet G and hold the sheet G against the mold 26 
after shaping. If desired, an alignment arrangement, e.g. a post and 
receiver system (not shown) or other system known in the art, may be used 
in the shaping station 14 to ensure proper vertical alignment between the 
upper mold 26 and flexible ring 38. 
After shaping, cylinder 66 moves the flexible ring 38 of lower mold 28 away 
from the shaped sheet G to a position below the rolls 24 and the actuators 
42 return the flexible ring 38 to its flat configuration. As the flexible 
ring 38 is lowered, the shaped glass sheet G is held against the upper 
mold 26 by vacuum. Tempering ring 68 is then positioned beneath the upper 
vacuum mold 26 to receive the shaped glass sheet G. The vacuum is then 
terminated and the glass sheet G is deposited on the tempering ring 68 
which thereafter conveys the shaped glass sheet G to the cooling station 
16 where the glass sheet G is controllably cooled to a temperature below 
its strain point temperature to temper the glass. 
As an alternative to the above shaping and pressing sequence, the cylinder 
66 and actuators 42 may be coordinated to lift the sheet G and 
preliminarily shape the sheet G before it is pressed against surface 30 of 
upper mold 26. More specifically, after cylinder 66 has lifted the sheet G 
off rolls 24 and positioned it in close proximity to the surface 30, the 
actuators 42 which support those portions of the marginal edge portion 46 
that require the greatest amount of vertical movement in order to contact 
surface 30, are energized. For example, to preliminarily shape a sheet G 
to a configuration as shown in FIGS. 3-6, the initially energized actuator 
42 would be the actuator furthest to the right in FIG. 3. Actuators 42 
would then be sequentially energized from right to left as viewed in FIG. 
3 to progressively deform and preliminarily shape the glass sheet G so 
that at least the marginal edge portion 46 of the glass sheet G has a 
shaped configuration that approximates the final desired shape for that 
portion of the sheet. After the sheet G is preliminarily shaped, the 
actuators 42 continue to move the deformed flexible ring 38 upward until 
the heat softened sheet G is engaged by the shaping surface 30 of upper 
mold 26 and the marginal edge portion 46 of the sheet G is pressed against 
surface 30 by the lower mold 28. As an alternative, further deformation of 
ring 38 by actuators 42 may be terminated and cylinder 66 may be used to 
lift the ring 38 and finally press the preliminarily shaped sheet G 
against upper mold surface 30. 
It should be appreciated that the movement of the lower mold 28 via 
cylinder 66 may be coordinated by controller 64 with the activation of the 
actuators 42 to shape the glass sheet G using sequences other than those 
discussed above. In particular, the actuators 42 may be energized and/or 
de-energized at any time prior to, during or after the movement of the 
flexible ring 38 by the cylinder 66 to perform any desired shaping and 
pressing sequence. For example, as discussed earlier, cylinder 66 may lift 
the flexible ring 38 so that it lifts the heat softened glass sheet G off 
the rolls 24 and into partial contact with surface 30 of the upper mold 
26. The actuators 42 would thereafter deform the flexible ring 38 and 
press the marginal edge portion 46 of the sheet G against a corresponding 
portion of surface 30 of upper mold 26. As another example, selected 
actuators 42 may be energized during cylinder 66's lifting of the ring 38 
and sheet G so that the sheet is being preliminarily shaped while it is 
still being lifted by the cylinder. 
Although the lower mold 28 of the invention as discussed utilizes a 
flexible ring 38 that supports the marginal edge portion of the sheet G 
about its entire periphery, the ring 38 may be modified so that it is 
sectionalized into separate, spaced apart flexible shaping rails which 
engage only selected marginal edge portions of the sheet G. For example, 
the flexible ring 38 may be limited to engage and press only the outermost 
wing portions of a heat softened glass sheet, i.e. the portions of the 
sheet G furthest to the right in FIGS. 3-6. The remaining marginal edge 
portions may be lifted and pressed against upper mold 26 by a rigid 
shaping rail (not shown) having a fixed shape, or those remaining portions 
may remain unsupported and lifted into engagement with surface 30 of the 
upper mold 26 as the sheet G is raised by the flexible rails but they 
would not be positively pressed against the surface 30 as would be the 
wing portions. 
It is also contemplated in the present invention that the need for lifting 
cylinder 66 may be eliminated. In particular, if the length of the stroke 
of actuator rods 54 is long enough, the actuator 42 may be used to 
initially lift the sheet G off the rolls 24 and preliminarily shape and/or 
press the sheet G against surface 30 of upper mold 26, using any desired 
operating sequence, such as but not limited to the operating sequences 
discussed above. 
Other variations as would be known to those skilled in the art based on the 
disclosure herein may be resorted to without departing from the scope of 
the invention as defined by the claims that follow.