Variable radius bowing press

A variable radius bowing press including a mandrel, a mandrel support and a subassembly. The subassembly comprises a housing, a wiper plate capable of pivoting with respect to the mandrel, and an actuator that exerts a force against the wiper plate, causing the wiper plate to pivot. An overbender capable of pivoting with respect to the mandrel may be connected to the wiper plate. An actuating device may be provided that exerts a force against the overbender and causes the over bender to pivot. The apparatus may include two substantially similar subassemblies capable of synchronized operation.

BACKGROUND OF THE INVENTION 
The present invention is concerned generally with a bowing press, and 
particularly with a bowing press capable of shaping articles into objects 
having various radii. 
It frequently is desirable to form substantially flat articles into a bowed 
shape for functional or decorative purposes. When the article to be shaped 
includes natural fibers, a risk exists that the bowing will damage the 
fibers, resulting in splintering or other undesirable conditions. 
Articles including natural fibers, such as hardwood splints, may be formed 
into a bowed shape manually. For example, the article may be wetted to 
increase its pliability, manually bent into conformance with a mold or 
other shaping device, secured in this conforming position, and allowed to 
dry. 
Manual bowing methods have numerous disadvantages. The manual bending of 
the article may be physically difficult to accomplish, particularly when 
this task is to be performed repeatedly. In addition to the physical 
difficulty of the manual forming and the risk of acute injury associated 
therewith, repetitive motions, such as those associated with manual bowing 
methods, may result in chronic injury in some individuals. 
Articles bowed by manual methods are susceptible to damage during the 
bowing process. The force necessary to conform an article to a shaping 
device may not be applied uniformly across the bowed portion, resulting in 
breakage of the fibers and splintering. The likelihood of fiber damage 
increases with the angle desired in the shaped object. The presence of 
irregularities or flaws, such as knots, in the articles to be bowed also 
increases the likelihood of fiber damage during bowing. Such fiber damage 
may adversely affect the strength or appearance of the bowed object, 
resulting in waste of both raw materials and labor. 
Manual bowing methods are also slow and imprecise. Generally, each article 
must be bowed individually. If the articles are not carefully and fully 
conformed to a shaping device, the resulting bowed objects may vary from 
one another in an unacceptable manner. 
In addition, manual bowing methods typically require that separate molds be 
formed for each particular bowed shape desired. Molds made of wood are 
susceptible to physical damage from the stresses of manual bowing as well 
as to deterioration over time when these molds are used to bend articles 
that must be wetted before bowing. 
The contents of applicant's parent application, U.S. patent application 
Ser. No. 08/322,915, is incorporated into the present disclosure by 
reference. 
An object of this invention is to provide an apparatus and method for 
bowing articles that reduces the physical demands associated with manual 
bowing methods. 
A second object of this invention is to provide an apparatus and method for 
bowing articles that is less labor intensive than manual bowing methods. 
A third object of this invention is to provide an apparatus and method for 
bowing articles that is faster than manual bowing methods. 
A fourth object of this invention is to provide an apparatus and method for 
bowing articles in which numerous objects may be bowed in a single 
operation. 
A fifth object of this invention is to provide an apparatus and method for 
bowing articles that results in consistent, uniformly shaped objects. 
A sixth object of this invention is to provide an apparatus and method for 
bowing articles that decreases damage to the articles during bowing, 
particularly when the articles include natural fibers. 
A seventh object of this invention is to provide an apparatus and method 
for bowing articles in which the articles to be bowed are supported upon a 
substrate during bending of the articles. 
An eighth object of this invention is to provide an apparatus and method in 
which the force exerted against the article to be bowed during bending is 
applied more uniformly. 
Another object of this invention is to provide an apparatus and method for 
bowing wooder articles that reduces the scrap rate associated with manual 
bowing methods. 
Yet another object of this invention is to provide an apparatus and method 
that requires fewer types of molds or shaping devices than conventional 
bowing methods, that provides more compact shaping supports for bowing an 
article, and that provides a shaping support for bowing an article that is 
more resistant to physical damage than conventional shaping supports. 
Still another object of this invention is to provide an apparatus and 
method in which the drying time of bowed objects formed from articles that 
require wetting before bowing is decreased. 
The present invention provides an apparatus and method that allows the 
bowing of articles having various radii, and that is faster, less labor 
intensive, and less physically-demanding than manual bowing methods. The 
apparatus and method of the invention permit the bowing of numerous 
articles in a single operation and yield consistent, uniformly shaped 
bowed objects. 
The present invention provides an apparatus and method in which pressure is 
exerted more uniformly upon the article to be bowed, thereby reducing 
damage to articles during bowing, and particularly to articles that 
include natural fibers. The present invention also provides an apparatus 
and method for bowing articles that decreases the scrap rate and permits 
bowed objects to be formed successfully from articles containing minor 
flaws or irregularities, such as knots, that would interfere with manual 
bowing methods. 
The apparatus and method of the present invention reduces the number of 
different shaping supports required to produce bowed objects having a 
variety of sizes and configurations when compared to manual bowing 
methods. The present invention also provides shaping supports that are 
less bulky and easier to store than conventional molds or shaping devices. 
The present invention also reduces the drying time of bowed objects formed 
from articles that require wetting before bowing to increase their 
pliability. 
SUMMARY OF THE INVENTION 
The foregoing objectives are achieved in a variable radius bowing press 
comprising a mandrel support, a mandrel which is removably connected to 
the support, a mandrel cam located within the mandrel support and in 
communication with the mandrel, and at least one subassembly. The 
subassembly includes a housing, a wiper plate connected to the housing and 
capable of pivoting with respect to the mandrel, and an actuator that 
exerts a force against the wiper plate, causing the wiper plate to pivot.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
In its preferred embodiment, the bowing press apparatus of the present 
invention incorporates two subassemblies that act in concert during a 
press cycle to form a material into a desired shape. One subassembly may 
also be remotely used to bend objects into alternative configurations. 
Each subassembly is substantially identical, with some exceptions noted 
herein. The following detailed description illustrates one subassembly and 
its composition, but is equally applicable to both subassemblies. It will 
be appreciated that minor changes may be made to the apparatus to 
facilitate molding various materials into different shapes. 
FIG. 1 shows a side view of subassembly 1 of the apparatus. The press 
incorporates two subassemblies that act together during a press cycle and 
rest upon a base frame. The housing includes at least two upwardly 
extending walls 9A, 9B that rest upon base frame 9C. Mandrel 7 is 
removably attached to horizontal mandrel support 8A. Mandrel support 8A is 
connected to vertical mandrel support 8B, which is fixed to base frame 9C. 
The mandrel's shape and associated radius is dependent on the shape of the 
article(s) to be bowed. The removability of the mandrel facilitates 
exchange of various mandrels having different configurations. 
The subassembly includes a gear rack assembly defined by gears 11 and 12, 
which are mounted on gear rack 13 and communicate with side rails 14A and 
14B, respectively. Side rails 14A and 14B connect subassembly 1 to 
subassembly 1' (shown in FIG. 2). In a preferred embodiment, a first end 
of side rail 14A is fixedly attached to housing 9B of subassembly 1 and a 
second end of side rail 14A is adjustably attached to housing 9B of 
subassembly 1'. Likewise, the first end of side rail 14B is fixedly 
attached to housing 9A of subassembly 1 and the second end of side rail 
14B is adjustably attached to housing 9A of subassembly 1'. Gear crank 15 
and locking mechanism 15A communicate with the gear rack assembly through 
housing wall 9A. The gear crank and gear rack assembly work in combination 
to allow movement of subassembly 1 transversely with respect to 
subassembly 1' to facilitate the bowing of differently sized articles or 
to allow for positioning of a mandrel having a different shape. Gear crank 
15, when rotated, engages the gear rack assembly causing the subassemblies 
to move transversely along base frame 9C. A flange wheel assembly, (not 
shown) located at the bottom of each subassembly communicates with the 
base frame to provide a low coefficient of friction between these 
components facilitate movability of each subassembly. Gear crank 15 also 
locks subassemblies 1 and 1' in position during press operation after a 
desired spacing of the subassemblies has been achieved. 
Cylinder 18 is fixedly connected to the housing by way of bottom cylinder 
support 10. Bending piston 19 protrudes upwardly from cylinder 18 and is 
connected to wiper plate support frame 6. The bending piston transmits a 
force exerted by cylinder 18 against the wiper plate/overbender 
combination as described hereinafter. Alignment guide 21, attached to 
bending piston 19, acts to prevent deflection of the force provided by 
cylinder 18. Accordingly, piston 19 must be composed of a material capable 
of withstanding and transmitting a force exerted by cylinder 18. By way of 
example, pneumatic cylinder 18 may have a six (6) inch bore and may be 
capable of exerting a force approximately equal to 4000 pounds per square 
inch. 
A pressure source is connected to the various cylinders in the apparatus by 
way of flexible tubing. The placement of this tubing is conducive to both 
user safety and convenience and provides satisfactory pressure for 
initiating each cylinder. In the preferred embodiment, all of the 
cylinders are pneumatic. However, hydraulic cylinders or like devices 
capable of exerting a sufficient force in a specified direction may be 
used, in the present configuration, the noise factor was considered in 
selecting pneumatic cylinders because the device is typically used on a 
factory floor where loud noise is commonplace; thus, any reduction in 
noise without loss of performance is desirable. 
A pinch plate platform assembly located between subassemblies 1 and 1' 
(shown in FIG. 2) includes pinch plate platform 70, adjustable screw jacks 
71 and 72, screw jack mounting plate 73, platform mounting bracket (shown 
in FIG. 2), and air actuators 78 and 79. The air actuators communicate 
with the pinch plate platform and, upon press activation, force the 
platform linearly upward toward mandrel 7. Jack adjustment 74 varies the 
height of the pinch plate platform 70 in its inactive (or lowermost) 
position relative to mandrel 7 by way of a mounting bracket (not shown). 
The desired platform height is dependent on the radius of the mandrel and 
the size of the articles to be bowed. Accordingly, as the radius of the 
mandrel or the size of the articles increases, the screw jacks are 
retracted, lowering the pinch plate platform; as the radius of the mandrel 
or the size of the articles decreases, the screw jacks are lifted, raising 
the pinch plate platform. 
FIG. 2 illustrates a front view of the variable radius bowing press with 
the outer housing plate 9A removed. Wiper plate 16 and overbender 22 are 
both rigid members which have an inactive and an active station. In the 
inactive station, the wiper plate and overbender define a substantially 
horizontal plane, and the wiper plate and mandrel 7 define a space 
therebetween for insertion of a forming tray (as shown in FIGS. 3A, 3B and 
3C). One end of overbender 22 is positioned substantially adjacent to the 
outer longitudinal side of wiper plate 16. The wiper plate, which is 
pivotally attached at its other end to wiper plate support frame 6, is 
positioned partially beneath and extends longitudinally and substantially 
parallel to mandrel 7. The wiper plate has a smooth durable surface which 
provides low resistance to sliding movement of a tray. 
Screw jack 71 and platform mounting bracket 77 are adjusted proportionately 
to the radius of the mandrel and size of the tray. As the press is 
activated by a user, air actuator 78 (together with air actuator 79, not 
shown in FIG. 2) forces pinch plate platform 70 linearly upward toward 
mandrel 7. Wiper plate 16 and overbender 22 are initially displaced, as a 
unit, linearly upward toward mandrel 7 by way of cylinder 18, bending 
piston 19 and wiper plate support frame 6. As the tray overlaying the 
wiper plate and overbender comes into contact with the mandrel, the wiper 
plate ceases to move linearly and is displaced pivotally by way of 
cylinder 18, bending piston 19 and wiper plate support frame 6. The wiper 
plate and overbender pivot radially along angle .THETA. relative to the 
press's horizontal plane. Angle .THETA. may vary depending on the 
curvature desired in the material to be bowed. When the wiper plate 
reaches angle .THETA., its movement ceases and overbender 22 continues 
pivotally and radially along angle .THETA.' by way of an additional 
cylinder 23. This cylinder is connected to a "U" shaped bracket 24 
containing a trunnion plate which maintains a constant angle relative to 
overbender 22 and allows the cylinder to move with wiper plate 16 to angle 
.THETA., where cylinder 23 is activated. The "U" shaped bracket imparts 
the cylinder's force directly onto overbender 22, thereby minimizing 
deflection. The overbender continues its radial movement to a desired 
angle .THETA.'. Thus, the forces exerted against the tray induce it to 
bend around the axial radius of mandrel 7 which results in the desired 
shape of a tray's contents. 
By way of example, wood splints may be placed in a tray to form round 
basket handles 34 of a shape illustrated in FIG. 3C. The tray containing a 
plurality of wood splints is placed in the press and rests upon wiper 
plate 16 and overbender 22. Upon activation, cylinder 18 applies a force 
which displaces the tray linearly upward toward mandrel 7 until the wood 
splints come into contact with the mandrel. Air actuators 78 and 79 force 
pinch plate platform 70 upwardly which assists in the linear upward 
movement of the tray's and the securing of the tray contents against the 
mandrel. Wiper plate 16 and overbender 22 are displaced by cylinder 18, 
rotatably along angle .THETA.. To achieve the handle shape in FIG. 3C, 
.THETA. is within the range of approximately 35 to 45 degrees. Upon 
reaching angle .THETA., cylinder 23 is actuated, thereby displacing 
overbender 22 along angle .THETA.'. For the handle shape in FIG. 3C, 
.THETA.' is within the range of approximately 80 to 90 degrees. These 
angle measurements are dependent on the size of the tray, the thickness of 
the articles to be bowed, and the radius of the mandrel. It should be 
noted that mandrels having different radii can be used, thereby allowing 
the tray's contents to be pressed in a particular configuration. Various 
cylinders may be used which are capable of imparting forces that bend more 
rigid material than wood splints. The space between each subassembly may 
also be changed to achieve a desired configuration in the article to be 
bowed. 
Returning to FIG. 2, as wiper plate 16 reaches angle .THETA., and as 
overbender 22 reaches angle .THETA. downward forces are exerted against a 
tray at the points where the tray rests on pinch plate platform 70. The 
pinch plate opposes the downward force exerted against the tray during 
bending, thereby assisting in preventing excessive or undesirable crowning 
of the center portion of the tray's contents during a press cycle. The 
thickness of the inner surface of the mandrel may be increased at 
predetermined locations to provide greater resistance to the force exerted 
against the tray, which also may assist in preventing crowning. The 
operation described above is performed substantially simultaneously with 
respect to subassembly 1'. 
Synchronizer bars 75 are attached at one end to wiper plate support frame 6 
and communicate perpendicularly with lower member 77' of pinch plate 
platform mounting bracket 77. The air actuators used in the present 
embodiment retract by operation of gravity. Thus, as a press cycle is 
completed and the pinch plate platform retracts to its inactive state, the 
synchronizer bars restrict the downward movement of the platform as it 
comes into contact with lower member 77' of platform mounting bracket 77. 
As discussed earlier, when a mandrel having a larger radius is employed, 
the pinch plate platform as well as the wiper plate/overbender combination 
must be lowered with respect to the mandrel. The synchronizer bars 
facilitate the retraction of these components as a unit. As adjustable 
screw jacks 71 and 72 are retracted, lower platform mounting bracket 
member 77' and synchronizer bar 75 are lowered, thereby lowering wiper 
plate support 6. Accordingly, the synchronizer bars act as a wedge to 
limit the downward movement of the pinch plate platform as well as the 
wiper plate/overbender combination. 
FIG. 3A is a side view of forming tray 30 which includes a tray body 33 
having an upper surface 36. The tray body is formed from a flexible but 
durable composition, such as stainless steel. Preferably, the tray is 
resistant to liquids and is capable of withstanding temperatures at least 
as high as 160.degree. F. FIG. 3B is a top view of a tray 30 having a 
substantially rectangular shape, but other configurations may also be 
used. An eye 37 or other fastener-receiving device may be provided on 
opposing sides of tray 30 for use in securing the ends of the bowed tray 
to one another. Preferably, the eyes 37 project transversely from the tray 
surface. 
Retainers 31 are arranged parallel to left and right edges of the tray body 
33 and are maintained at a desired distance above the tray body 33 by 
spacers 35. The retainers 31 overhang the spacers 35. 
The height of the spacers 35 corresponds to the thickness of the articles 
to be bowed so that the ends of the article may be inserted into the slots 
35A defined by the retainers 31 and the tray body 33. Although a 
particular spacer height may accommodate articles that vary slightly in 
thickness, a differently-sized spacer may be required to accommodate large 
variations in thickness. 
A retainer 31 may be movably connected to a spacer 35 by a fastener 32. 
Preferably, the fastener 32 is inserted through a slot or bore (not shown 
in the drawings) provided in the retainer 31 and extends into the spacer 
35 such that the retainer 31 is capable of moving from a first position to 
a second position relative to the tray body 33. When a slot is arranged 
perpendicular to or diagonally with respect to the retainer's longitudinal 
dimension, the retainer is capable of sliding from an inward position 
suitable for securing articles within the tray to an outward position 
suitable for releasing the objects from the tray. Alternatively, the 
retainer may slide vertically along the shaft of fastener 32 from a lower 
position suitable for securing articles within the tray to an upper 
position suitable for releasing articles from the tray. The retainer may 
also be hingedly connected to the tray having an active and an inactive 
position. In its active position, the retainer engages the tray's 
contents; in its inactive position, the retainer is displaced radially 
away from the tray's contents to allow removal of the contents 
Upon completion of a press cycle, the tray 30 and its contents 34 are bent 
about the mandrel as illustrated in FIG. 3C. The tray bracket 41 is 
fastened between the eyes 37 to secure the opposing ends of the tray 30 to 
one another while the tray is in the bent position. After the tray bracket 
41 is inserted, the tray 30 may be removed from the press. However, 
tension between the tray, the mandrel, the pinch plate platform and the 
overbender/wiper plate assembly prevents removal of the tray. Thus, a 
mechanism must be employed to release this tension before the tray can be 
removed. 
FIG. 4 is a perspective view of mandrel 7, horizontal mandrel support 8A 
and vertical mandrel support 8B. Although the mandrel is shown in two 
sections, 7A and 7B, which are removably attached to horizontal mandrel 
support 8A by way of mandrel bores 102, 103 and 104, a one-piece mandrel 
may also be employed. Mandrel cam 105 is located within horizontal mandrel 
support lumen 106 and extends substantially the longitudinal dimension of 
horizontal mandrel support 8A. The diameter of cam 105 is sufficiently 
less than the diameter of lumen 106 to allow for controlled movement 
therebetween. Cylinder 101 is attached to the horizontal mandrel support 
and is capable of exerting a force against mandrel cam 105 to facilitate 
movement of the mandrel cam within the mandrel cavity. 
The mandrel cam has an inactive and an active station as illustrated in 
FIGS. 4A and 4B respectively. FIGS. 4A and 4B are cut-away cross-sectional 
views of the mandrel and related members. Mandrel cam 105 communicates 
with pins 107, 108 and 109 located in bores 102, 103 and 104, 
respectively. Mandrel cam 105 communicates with pins 107, 108 and 109, 
which may be received within bores 102, 103 and 104, respectively. Pin 107 
communicates with cam 105 by way of bore 102. In its inactive station, as 
shown in FIG. 4A, pins 107 and 107' communicate with the indented portion 
of cam 105, which allows mandrels 7A and 7B to be in substantially flush 
contact with mandrel support 8A. The cam has an indented shape at each 
corresponding pin location. Upon activation of a press cycle, cylinder 101 
drives mandrel cam 105 into its active station whereby the cam is 
displaced (in direction "N") within mandrel lumen 106. This forces pin 107 
(and associated pins 108, 109) to ride the inclined portion of cam 105 and 
protrude transversely relative to mandrel support 8A. The protrusion of 
the pins displaces mandrel 7A and 7B transversely from horizontal mandrel 
support 8A, as illustrated in FIG. 4B (displacement distance referenced by 
200). The mandrel cam remains in its active station while the press cycle 
continues and a tray is bowed around the axial radius of the mandrel. Upon 
completion of the cycle, cylinder 101 is deactivated and the mandrel cam 
and pins return to their inactive stations. This relieves the tension on 
the tray and facilitates easy tray removal. 
The apparatus of the present invention may be used as described below. This 
description assumes that more than one article will be bowed in a single 
operation. However, the apparatus and method of the present invention may 
also be used to bow a single article, provided the width of the article is 
slightly less than the width of the forming tray and the length of the 
article is no more than slightly longer than the length of the forming 
tray. 
Before loading the articles to be bowed into a forming tray, the articles 
may be wetted to increase their pliability. The wetting may be 
accomplished by immersing the articles, such as wood splints, in water or 
another suitable softening medium. The immersion time and water 
temperature may be adjusted depending on such factors as the type, 
condition and thickness of the article to be bowed, the bowing angle 
desired, and whether discoloration of the resulting bowed object is 
undesirable in a particular application. Preferably, wetted objects will 
be loaded into the forming trays as soon as possible after they are 
removed from the water. If the articles to be bowed are sufficiently 
pliable, however, wetting may not be required. 
The splints or other articles to be bowed may be loaded onto the forming 
tray 30 in substantially abutting parallel relationship, as shown in FIG. 
3B. The opposing ends of the articles are inserted into the slots 35A 
defined by the retainers 31 and the tray body 33. When a desired number of 
objects has been loaded into the tray 30, the tray may be inserted into 
the bowing press. 
FIG. 5 is a perspective view of the press in its inactive station. The 
loaded tray is placed on the press in space 17, whereby mandrel 7 acts as 
a fulcrum point around which the tray is bent. To facilitate proper tray 
placement, tray stopper 50 is connected to the upper surface of an 
overbender 22 at a specified distance from the pinch plate platform 70. A 
tray end abuts the tray stopper, assuring a user that the tray is 
positioned correctly. As different sized trays are used, the tray stopper 
may be adjusted accordingly on overbender 22. A rear tray stopper may also 
be provided, for example, on wiper plate 16, 16' or overbender 22, 22', to 
guide placement of the rear of a tray. 
Upon press activation, as illustrated in FIG. 6, pinch plate platform 70 
and wiper plate support frame 6 force tray 30 linearly upward toward 
mandrel 7A, 7B. Mandrel cam 105 is initiated into its active station 
whereby pins 107, 108, and 109 are displaced transversely outward with 
respect to mandrel support 8A. The pins force mandrel 7A and 7B to expand 
outward from the horizontal mandrel support. Wiper plate 16 bends tray 30 
along angle .THETA. and overbender 22 continues radially along angle 
.THETA.' by way of cylinder 23 and "U" shaped bracket 24. Upon reaching 
the desired bowing angles, brackets 41 are placed in eyes 37 of tray 30 to 
retain the tray in its bent configuration (as shown in FIG. 3C). After the 
bending of the tray and placement of the brackets is complete, mandrel cam 
105 returns to its inactive station, releasing the tension exerted on tray 
30. Likewise, wiper plate 16 and overbender 22 return to their respective 
inactive stations and the bowed tray is removed from the press. 
The tray and its contents are set aside to rest and, if the splints have 
been wetted, to dry. If the splints have been wetted, the bowed tray may 
be inverted during drying so that the tray edges rest on the supporting 
surface to assist in draining water away from the tray contents. The 
optimum time and temperature for curing and drying may vary with the 
composition and thickness of the bowed objects. If the bowed objects are 
not permitted sufficient curing or drying time after bowing, the objects 
will not retain the desired shape after they are removed from the forming 
tray, but instead will tend to open up into a less bowed shape. This 
tendency may be obvious immediately after the objects are released from 
the tray. If the bowed objects remain within the trays for an extended 
period after the bowing process, the risk of damage to the bowed objects 
during removal from the tray increases. 
Returning to FIG. 3C, the bowed objects may be released from the tray as 
follows. Tray bracket 41 is removed from the tray eyes 37 shown in FIG. 
3C. The fasteners 32 that extend through the retainers 31 and into the 
spacers 35 may be loosened along one edge of the tray 30 as shown in FIG. 
3A. When these fasteners 32 are loosened, the retainer 31 may be moved 
away from the tray body 33, freeing an end of the bowed objects from the 
slot 35A between the retainer 31 and the tray surface 33. The other end of 
the bowed objects then may be moved out of the slot 35A on the other edge 
of tray 30. 
By way of example, the apparatus and method of the present invention may be 
used to bow hardwood splints to form basket handles. Thin maple splints in 
the range of approximately 3/16th-inch thick are immersed for a minimum of 
about 10 to 15 minutes in water, preferably maintained at a temperature of 
about 140 to about 160.degree. F. Immersion for periods of more than about 
25 minutes is likely to result in discoloration of the splints. 
FIG. 3C is an end view of a bowed tray of splints 34 that have been formed 
into a configuration desirable for round basket handles. Trays holding 
bowed handles formed from wetted maple splints typically are dried in an 
area having adequate air circulation and a temperature of up to about 
160.degree. F. for approximately 7 hours. When the resulting bowed object 
remains in a forming tray for more than about 12-14 hours, the risk of 
splint cracking increases. Although a specific embodiment of the invention 
has been described herein in detail, it is understood that variations may 
be made thereto by those skilled in the art without departing from the 
spirit of the invention or the scope of the appended claims.