Hot and cool air bonding apparatus

An apparatus and method is disclosed for bonding a fiber reinforced plastic automotive body member to a reinforcement member. An adhesive is located between mating surfaces of the body member and the reinforcement member. Pressurized heated and cool air is used to heat and facilitate the cooling of the adhesive. The apparatus includes a switchable heating and cooling system that first provides pressurized heated air about outer surfaces of the body member and the reinforcement member, and thereafter, the system provides pressurized cool air about the same outer surfaces.

BACKGROUND OF THE INVENTION 
1. Technical Field 
This invention relates to bonding apparatuses and techniques and, more 
particularly, to an apparatus and method for bonding automotive fiber 
reinforced plastic (FRP) members together. 
2. Discussion of the Related Art 
Various techniques are currently employed for bonding fiber reinforced 
plastic (FRP) members together for use in automotive body applications 
such as, but not limited to, hoods, doors, bumpers, and the like. There 
has been an outgrowth in the number of apparatuses and methods available 
for producing bonded FRP assemblies due to the growing trend in the 
automotive industry to replace heavier metal components with plastic 
assemblies. These assemblies are typically bonded by heating an adhesive 
placed between the mating surfaces of two FRP members to a temperature 
exceeding its curing temperature. 
FIGS. 1-3 illustrate in simplified manners, examples of well known bonding 
techniques that use heat to bond an FRP assembly consisting of FRP members 
10 and 12 with adhesive 14 placed therebetween. FIG. 1 illustrates 
dielectric heating apparatus 16 that produces radio frequency 
electrostatic fields between electrode 18 and block member 20. The 
electrostatic fields quickly heat adhesive 14 to a temperature above its 
curing temperature to thereby bond FRP members 10 and 12. Commonly 
assigned U.S. Pat. No. 4,941,936 to Wilkinson et al. and U.S. Pat. No. 
4,941,937 to Iseler et al. disclose examples of dielectric heating 
techniques which are hereby incorporated herein by reference. Dielectric 
heating techniques have the advantage of reducing cycle times along with 
the accompanying disadvantage of heating an FRP assembly in a manner that 
is difficult to control and maintain. 
FIG. 2 illustrates bonding apparatus 22 that utilizes cartridge heaters 28 
for heating metal block members 24 and 26. Block members 24 and 26 in turn 
heat the air flowing through air circuits 30, a portion of which, flows 
through openings 32 for heating adhesive 14 between FRP members 10 and 12. 
One disadvantage with this type of bonding technique is that it requires a 
large supply of compressed air to operate efficiently. 
FIG. 3 illustrates bonding apparatus 34 that utilizes heated steam and/or 
hot water flowing through passages 40 for heating metal block members 36 
and 38. Block members 36 and 38 in turn heat adhesive 14 between FRP 
members 10 and 12. This bonding technique has the disadvantage of 
requiring a high cycle time when compared to the bonding techniques 
illustrated in FIGS. 1 and 2. 
When bonded FRP assemblies are used in exterior automotive body 
applications, it is of the utmost importance that the bonding technique 
employed does not adversely effect the surface qualities of the exterior 
FRP members and that the technique provides even bonding not withstanding 
the size of the FRP members. 
Thus, it would be desirable to produce a bonding apparatus that improves 
the surface qualities of a resulting FRP assembly and that provides 
uniform bonding strength throughout the assembly. Further, it would be 
desirable to provide a bonding technique that expeditiously adheres a 
first FRP member to a reinforcement FRP member without affecting surface 
qualities or bonding strength characteristics. 
SUMMARY OF THE INVENTION 
Pursuant to the present invention, a bonding apparatus and method for 
expeditiously bonding automotive fiber reinforced plastic (FRP) members is 
disclosed. The apparatus provides the resulting bonded assembly with 
uniform bonding characteristics and improved surface qualities. While the 
present invention will be described in connection with the bonding of FRP 
members, it will be understood that other plastic materials or even metal 
may be used. 
In accordance with the teachings of one embodiment of this invention, an 
apparatus is provided for bonding a first member, typically an automotive 
outer skin member, to a reinforcement member. An uncured adhesive is 
located on the mating surface of the first member. First and second nest 
members are provided for receiving and supporting the first member and the 
reinforcement member in a spaced relationship. Relative movement of the 
nest members is controlled such that the mating surface of the first 
member engages a corresponding mating surface of the reinforcement member 
with the adhesive therebetween. Switchable heating and cooling assemblies 
first provide pressurized heated air to the nest members that in turn 
channel the heated air about portions of the outer surfaces of the first 
member and the reinforcement member. Thereafter, the switchable heating 
and cooling assemblies provide cool air to the nest members which in turn 
channel the cool air about the same portions of the outer surfaces of the 
first member and the reinforcement member. The pressurized heated air 
heats the adhesive to a temperature exceeding its curing temperature, and 
the pressurized cool air facilitates the cooling process for the resulting 
assembly. 
In the preferred embodiment, after the pressurized heated air has been 
provided to the nest members, a bypass chilling system provides 
pressurized chilled air to the nest members which in turn channel the 
chilled air about portions of the outer surfaces of the first member and 
the reinforcement member, thereby decreasing the time required for the 
resulting assembly to cool.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The following description of the preferred embodiments is merely exemplary 
in nature and is in no way intended to limit the invention or its 
application or uses. 
The present invention is particularly concerned with bonding reinforced 
exterior automotive body assemblies such as, but not limited to, hoods, 
doors, and bumper assemblies. The invention provides an apparatus and 
expeditious method for bonding a first, typically exterior, fiber 
reinforced plastic (FRP) member to a second reinforcement member, which is 
also preferably manufactured of a FRP material although other plastic 
materials or even metal may be used. 
The invention is described in detail below with reference to the 
manufacture of an automotive hood assembly, however, it will be 
appreciated by those skilled in the art that the present invention, as 
defined by the appended claims, is clearly not limited to this particular 
application. Furthermore, the invention is described with reference to the 
hood assembly members being formed from FRP materials, however, it will be 
appreciated by those skilled in the art that the use of other plastic 
materials or metals is within the scope of the present invention. Hood 
assembly 42 is illustrated in the drawings and consists of a relatively 
thin (about 0.080 to 0.120 inch thick) outer skin member 44 and 
reinforcement member 46. Outer skin member 44 and reinforcement member 46 
are constructed of FRP material and are preferably made from thermosetting 
sheet molding compound (SMC) material which has been compression molded 
under vacuum. U.S. Pat. Nos. 4,488,862; 4,551,085; and 4,612,149 owned by 
the Budd Company of Troy, Mich., relate to such techniques and are hereby 
incorporated herein by reference. Outer skin member 44 includes outer 
surface 48 and inner mating surface 50. Similarly, reinforcement member 46 
includes outer surface 52 and inner mating surface 54. 
In order to bond outer skin member 44 to reinforcement member 46, a bead of 
adhesive 56 is laid on a mating portion of inner mating surface 50. The 
adhesive 56 is a thermosetting resin that exhibits a change in dielectric 
properties when cured. The adhesive 56 preferably contains a resin 
consisting of uncrossedlinked polymers and monomers, with a second part 
consisting of a hardener or catalyst. Epoxy resin adhesives are presently 
preferred, although polyurethanes should prove to be acceptable. These 
adhesives are to be distinguished from glues such as animal glues which do 
not rely upon a chemical change to effect their adhesive qualities. As 
will appear clear from the following discussion, the present invention 
utilizes this characteristic of certain adhesives to great advantage. By 
way of a specific, but nonlimiting example, adhesive 56 is a Lord 
380.backslash.382 epoxy adhesive available from Lord Corporation. 
As shown in a simplified manner in FIG. 5, reinforcement member 46 is 
preferably preheated in quartz heating apparatus 58 or any other suitable 
type of heating unit prior to being bonded with outer skin member 44. 
In FIG. 8, hot and cool air bonding apparatus 60 is shown in a partial 
cutaway perspective view and is in a closed position with the outer 
skin/adhesive/reinforcement member assembly 42 located therein. 
FIG. 7 is a cross-sectional view of hot and cool air bonding apparatus 60 
in an initial open position. With apparatus 60 in the open position, outer 
skin member 44 and reinforcement member 46 are carried into bonding 
apparatus 60 with reinforcement member 46 positioned within first nest 
member 62 and outer skin member 44 positioned within second nest member 
70. As will be apparent to those skilled in the art, this can be 
accomplished in a variety of manners. Reinforcement member 46 is secured 
by vacuum assemblies 64 that include vacuum cups 66. Locators 68 ensure 
that reinforcement member 46 is in a proper position prior to being 
bonding with outer skin member 44. In a similar fashion, outer skin member 
44 is secured by vacuum assemblies 72 that include vacuum cups 74. Vacuum 
assemblies 64 and 72 are connected to a standard vacuum source, not shown. 
Support members 76 support and position skin member 44 in a proper 
position prior to being bonding with reinforcement member 46. First nest 
member 62, locators 68, and vacuum assemblies 64 are all rigidly attached 
to base member 78 which in turn is coupled to hydraulic cylinders 80 as 
shown in FIG. 8. Similarly, second nest member 70, vacuum assemblies 72, 
and support members 76 are all rigidly secured to base member 82. 
Hydraulic cylinders 80 and guide posts 150, provided at the four corners 
of apparatus 60, control the movement of apparatus 60 between the open and 
closed positions. Cylinders 80 cause base member 78 to move in the 
direction of base member 82 until inner mating surface 54 of reinforcement 
member 46 contacts adhesive 56 located on inner mating surface 50 of outer 
skin member 44. 
As best shown in FIG. 6, which is a plan view of second nest member 70 with 
outer skin member 44 removed, second nest member 70 has a modular design 
and is formed from a series of individual block members 84. Each of block 
members 84 is individually secured to base member 82 by bolts 86. Block 
members 84 are preferably made from aluminum but can be made from any 
other metal or suitable material. As is apparent, the series of block 
members 84 form a closed loop that substantially corresponds to the shape 
of the outer periphery of outer skin member 44. Block members 84 include 
top surfaces 88 that have contours respectively corresponding to the 
contours of outer surface 48 of outer skin member 44. 
As is best shown in FIG. 9 which is a partial cross-sectional view 
illustrating apparatus 60 in the closed position, slots 90 are formed 
within each of top surfaces 88 of block members 84. Returning to FIG. 6, 
when the series of block members 84 are secured to base member 82, slots 
90 are aligned and form a single slot extending around the closed loop 
formed by block members 84. Bonding manifold 92 is positioned within slots 
90 and includes apertures 94 that are formed in the direction towards 
outer skin member 44. Bonding manifold 92 is preferably made out of 
stainless steel tubing. Connector tubes 96, also preferably made out of 
stainless steel tubing couple bonding manifold 92 to main manifold 98 that 
is located on the outer periphery of second nest member 70. Main manifold 
98 is also preferably formed from stainless steel tubing. 
Returning to FIG. 7, first nest member 62 is also modular in design and is 
formed from a series of block members 100 that are individually secured to 
base member 78 by bolts 102. Block members 100 are also preferably made 
from aluminum but can be made from any other metal or suitable material. 
As with second nest member 70, block members 100 are positioned in series 
and form a closed loop that is a mirror image of the closed loop formed by 
second nest member 70. It should be noted that the modular designs of 
first and second nest members 62 and 70 allows block members 84 and 100 to 
be individually interchanged and/or replaced to reflect changes in the 
configuration of the members being bonded. As most clearly shown in FIG. 
9, block members 100 include top surfaces 104 that have contours 
respectively corresponding to the contours of the outer surface 52 of 
reinforcement member 46. As with block members 84, slots 106 are formed 
within each of surfaces 104. When the series of block members 100 are 
secured to base member 78, slots 106 are aligned and form a single slot 
extending around the closed loop formed by block members 100. Bonding 
manifold 108, preferably made out of stainless steel tubing, is positioned 
within slots 106 and includes apertures 110 that are formed in a direction 
towards reinforcement member 46. Connector tubes 112, also preferably made 
out of stainless steel tubing, couple bonding manifold 108 to main 
manifold 114 that is located on the outer periphery of first nest member 
62. Main manifold 114 is also preferably formed from stainless steel 
tubing. It should be noted that the shape and diameters of bonding 
manifolds 92 and 108, connector tubes 96 and 112, and main manifolds 98 
and 114 are used by way of example and other shapes and diameters are 
within the scope of the invention. Additionally, stainless steel is used 
by way of example and other suitable materials are within the scope of the 
present invention. 
As is shown in FIG. 8, bonding apparatus 60 includes two switchable heating 
and cooling assemblies 116 and 118. Assembly 116 provides pressurized air 
to main manifold 98 that in turn directs the air through connector tubes 
96 to bonding manifold 92. The air is then forced through apertures 94 in 
the direction of outer surface 48 of outer skin member 44. In a similar 
fashion, assembly 118 provides pressurized air to main manifold 114 that 
in turn directs the air through connector tubes 112 to bonding manifold 
108. The air is then forced through apertures 110 in the direction of 
outer surfaces 52 of reinforcement member 46. 100 and 84 of nest members 
62 and 70 cooperate in a manner such that slots 106 and 90 respectively 
form channels above reinforcement member 46 and below outer skin member 
44. The forced air that is expelled through apertures 94 and 110 enters 
these channels and exerts substantially equal pressure on outer surfaces 
48 and 52, thereby improving bonding characteristics of the resulting 
assembly 42. In order to facilitate the flow of the forced air through 
slots 106 and 90, apertures 134 and 136, extending from within slots 106 
and 90 through block members 100 and 84 to the surrounding atmosphere, 
allow a portion of the forced air to exit slots 106 and 90. 
FIG. 10 is an illustration of the air flow through switchable heating and 
cooling assembly 118. It will be apparent that the air flow through 
assembly 116 is accomplished in a similar fashion. It should be noted that 
assemblies 116 and 118 have the same features and are described below with 
reference to assembly 118. In accordance with the preferred embodiment, 
blower unit 120, which is driven by electric motor 122, draws air from the 
environment surrounding apparatus 60 through air filter 124, cooling unit 
126, and muffler 128. During the heating phase of the bonding process, 
cooling unit 126 is disabled and valve 152 is set such that the blower 
unit 120 forces the air through heater 130. The air is quickly heated to a 
specified temperature and forced through main manifold 114 and connector 
tubes 112 to bonding manifold 108. The heated air then exits through 
apertures 110 into slots 106 in the direction of outer surface 52. 
Insulation 132 and 144 is respectively located between bonding manifolds 
108 and 92 and block members 100 and 84. Insulation 132 and 144 minimizes 
the transfer of heat between bonding manifold 108 and block members 100 
and between bonding manifold 92 and block members 84. This reduction in 
the transfer of heat in turn reduces temperature changeover times for 
bonding manifolds 108 and 92. 
After assembly 118 has provided heated pressurized air for a predetermined 
time period, heater 130 is disabled, cooling unit 126 is activated, and 
valve 152 is reversed such that an air passage to bypass duct 142 is open. 
Blower unit 120 draws air through activated cooling unit 126 such that the 
air is chilled and forces the chilled air through bypass duct 142 to main 
manifold 114. The chilled air is then forced through connector tubes 112 
to bonding manifold 108. The chilled air then exits through apertures 110 
into slots 106 in the direction of outer surface 52. The application of 
the chilled air to assembly 42 reduces the time required for assembly 42 
to cool down. It will be apparent to one skilled in the art that 
assemblies 116 and 118 may be constructed without cooling unit 126, valve 
15, and bypass duct 142. In such an embodiment, during the cooling phase 
of the bonding process, heater 130 is disabled and blower unit 120 
continues to draw air through air filter 124 and muffler 128. The air is 
forced through heater 130 in such a manner that heater 130 is quickly 
cooled down. This air is then directed to main manifold 114 and eventually 
to bonding manifold 108. This air exiting bonding manifold 108 through 
apertures 110 is at a sharply reduced temperature when compared to the air 
that was flowing prior to heater 130 being disabled. 
In order to precisely control the amount of forced air entering bonding 
manifolds 92 and 108, connecting tubes 96 and 112 are provided with valves 
138. In addition, as shown in FIG. 8A, in order to monitor the approximate 
temperature of the forced air exiting bonding manifolds 92 and 108, 
thermocouples 140 are provided in close proximity to apertures 134 and 136 
within block members 100 and 84. 
In accordance with the method of bonding in accordance with the present 
invention, bonding apparatus 60 is initially in an open position as shown 
in FIG. 7. Reinforcement member 46 and outer skin member 44, with adhesive 
56 on mating surface 50, are positioned within nest members 62 and 70 in a 
spaced relationship. Next, hydraulic cylinders 80 cause base member 78 to 
move in a direction towards base member 82 until mating surfaces 50 and 54 
are engaged with adhesive 56 therebetween. Next, during the heating phase 
of the bonding process, switchable heating and cooling assembles 116 and 
118 supply heated air to bonding manifolds 92 and 108 and ultimately hood 
assembly 42 as previously described above. This heated air is supplied at 
a pressure within the range of 0.5 to 8 pounds per square inch at a 
temperature of approximately 550.degree. F. This heated air is supplied 
for approximately 15 seconds. Thereafter, assemblies 116 and 118 provide 
cooler temperature air, as previously described above, to bonding 
manifolds 92 and 108 and hood assembly 42 for approximately 45 seconds at 
a pressure within the range of 0.5 to 8 pounds per square inch. It will be 
apparent to one skilled in the art, that when the pressurized heated air 
is provided within slots 90 and 106, the adhesive between outer skin 
member 44 and 46 is heated to a temperature above its curing temperature 
such that outer skin member 44 and reinforcement member 46 are evenly 
bonded. As will be apparent to one skilled in the art, the pressure, 
temperature, and time period at which the hot and cool air is provided to 
slots 90 and 106 is used by way of example, and other operating parameters 
are within the scope of the present invention. 
From the foregoing it can be seen that use of the hot and cool air bonding 
apparatus improves the surface qualities of a resulting FRP assembly and 
provides uniform bonding strength throughout the assembly. Further, 
compared to the prior art bonding techniques, the hot and cool air bonding 
apparatus expeditiously bonds the FRP assembly without adversely affecting 
surface qualities or bonding strength characteristics. 
The foregoing discloses and describes merely exemplary embodiments of the 
present invention. One skilled in the art will readily recognize from such 
discussion, and from the accompanying drawings and claims, that various 
changes, modifications, and variations can be made therein without the 
departing from the spirit and scope of the present invention as defined by 
the following claims.