Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF PRODUCING AUTOMOTIVE BODY
SPECIFICATION
BACKGROUND OF THE INVEN~ION
The present invention relates to a method of the production
of a body of a motor vehicle. The production of an automobile
body is a highly automated procedure. The process of making a car
body can be summarized as a sequence of steps each of which steps
is well known in the art.
A number of metallic parts of the body of a car are welded ~ - -
together. During the welding, certain parts are placed in --
contact with each other ready for being welded to each other.
Before the welding, so-called ~hot melt strips" are placed
between the metallic parts. The two or more metal parts are then --~
welded to each other, e.g. by spot welding. The hot melt strips --
are plastic strips containing sealant. When the body is submitted ~ ~ -
to an elevated temperature, typically in an oven after the
application of paint, the "hot melt strips" are cured and in the
curing process, the sealant fills the selected void between the
two metal parts welded together. The purpose of this process i~
to secure waterproof quality of the respective section of the
body, e.g. the so-called fire wall separating the engine
25 compartment from the interior of the body. -
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In what is a subsequent or a simultaneous step, other parts
of the body are soldered to each other. This operation is usually
carried out on exterior part~ of the body. A good example is a - -
30 the soldering of a roof component to the columns of a car body. ;
The soldered parts are eventually welded to the rest of the metal
components of the body being produced. ;i
When the welding and soldering of the body component6 is
finished an intermediate produ¢t is obtained whiah is referred to
a~ a prefinished body portion. It is followed by mechanical
attachment of further components, suah as doors, to the
prefinished body portlon, to arrive at what is referred to as a
"metal finished body."
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The metal finished body i8 then passed through a phosphate
rinse or shower as a preparation for paint application and the
phosphate rinsed body is then submerged in a bath of primer. The
primer is so called E-coating. It is attracted to the metal body
5 by a very high voltage applied to the body. Typically the voltage
is in the range of 12,000 volts. The primer coated body is then
passed through an oven and thereafter provided with layers of
paint. Each application of paint is usually followed by another
oven. In the oven, the body is heated to a temperature of about
10 400 degrees Celsius or even more. One of the desired effects of --
the treatment in the oven is the curing of the sealant inserted
between adjacent metal parts at the outset of the production.
The use of hot melt sealant, its method of using and
15 application is well known in the art. Reference may be had, for
instance, to U.S. Patent 4,749,434 (Harrison), in which the
sealant, its use and production is described in detail. The heat
treatment of the coating applied is also known. See, for
instance, U.S. Patent 4,7871,728 which contains description of
20 treatment of the E-coat referred to above but also of a paint.
The pre-rinsing of the workpiece prior to being immersed in a
phosphatic or electro-painting solution is referred to for
instance, in U.S. Patent 4,600,491. Other patents describing
prior art relevant to the present invention include U.S. Patent
25 4,621,187 ~Petro, Jr.) and U.S. Patent 4,662,086 (Hennecke et
al.). --
one of the drawbacks of the known methods is that the high
voltage required to attract the E-coat (primer), causes undesired
30 release of small particles from the previously applied hot melt
i3trips. These are uncured synthetic material bits. They become
released into the bath of the primer and subsequently attached,
together with the primer, to the surface of the body submersed in
the bath.
Furthermore, the solder bakes out at the same stage giving
rise to still further defects of the same nature. These defects
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are normally disoovered only after the application of at least
the primer and often even after the sub~equent baking which
follows the application of the paint.
Despite the fact that these defects have long been
recognized, no effective solution has been found as yet. It is an
object of the present invention to alleviate the above problems.
SUMMARY OF THE I NVENTI ON
In accordance with the present invention the problems
associated with the release of the particles of the sealant from
the hot melt strips and the solder can be substantially reduced
and even entirely avoided by an extremely simple and therefore
even more surprising solution: the introduction of an additional -
oven through which the body is passed before the stage of the
phosphate rinsing. This has the result that the sealant which is ~ -
the essential material of the hot melt strips wilI become cured ~
and that the solder will bake out before the body is phoæphate -
rinsed metal finishing is carried out. The defects can be
relatively easily spotted eliminated and during the subsequent
treatment in the phosphate rinse and E-coat bath the possibility -~
is eliminated of uncured particles and there sticking to the
surface since all of the material had already been cured during
the passage through the additional oven.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is diagrammatically shown in the enclosed
drawings, wherein
Figure 1 is a block diagram of a typical known method of
producing an automobile body;
Figure 2 is a block diagram similar to that,of Figure 1 but
showing a first embodiment of the method of the present
invention; and
Figure 3 is a block diagram similar to that of Figure 1 but
showlng a second embodiment of the method of the pre~ent
invention. ~ '
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DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS
Turning firstly to Figure 1 and referring to the preceding
description, reference number 10 designates the step of welding
the respective metallic components of a car body to each other.
While a large number of components is involved, for the sake of
clarity, reference may be had to "at least two" such components.
The step 10 also includes the placement of hot melt strips
mentioned above, between the respective two or more components
welded together.
The block 11 shows the step of soldering as outlined above
and the subsequent step 12 is the final part of concluding what
is referred to as metal finishing stage of the body by attaching
to it components such as doors, bumpers etc. The metal finished
body is then passed through a phosphate rinsing stage 13 which is
a part of an intense cleaning of the body prior to the
application of paint. In the next step 14, the electrodepositio.n
described above takes place. This stage is commonly referred to
as E-coat or E-dip. The body emergi~g from the E-coat stags is
referred to as a primer "covered" body. If desired, it may be
passed through an oven 15 and from there a number of paint layers
is applied in paint application steps 16, each usually followed
by a paint baking oven and 17. The number of stages 16 and 17 is
optional. It is not neaessary that each be followed by an oven.
Nor is it vital that the E-coating stage 14 be followed by an
oven. It i5 important to note, however, that the purpose of the
first oven following the E-coating stage 14 (in the example
shown, the oven 15) is not only to bake th0 deposited primer but -
also to cure the plastic sealant inserted at the step 10.
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Thus, the prior art method depicted in Fig. 1 can be
described, in a very simplified summary, as follows: welding -.
soldering - metal finishing - phosphate treatment - E-coat -
paint - baklng.
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Turning now to Fig. 2, it will be seen that the same
exemplary basic steps 10 - 17 are included in the first
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embodiment of the inventive method. They are referred to with the
same reference numbers. However, the method of the present
invention includes a heat treatment in an oven 18 placed, in the
embodiment shown, between the metal finishing stage 12 and the
phosphate rinsing stage 13.
The oven 18 is of a type well known in the art and
described in a vast number of prior art references, some of which
have been mentioned above. The structure of the oven itself i8
not a part of the present invention. It will suffice to say that
the purpose of placement of oven 18 at the position shown is to --
subject the body to heat treatment which is sufficient to cure
the hot melt strip applied in step 10 and, if necessary, the -
solder applied in step 11. A typical temperature, as mentioned, -~
for instance, in the aforesaid U. S. Patent 4,749,434 is 240-F to
about 300 F. The temperature used may differ from the above
depending on the type of hot melt sealant used. The purpose of -
the oven 18 is to subject the body to heat treatment which
results not only in the curing mentioned but also in release of
small particles of the hot melt sealant and solder. However,
since the body is dry, the released particles do not stick to
its surface and even if they do, they can be eaæily removed, for
instance by vacuuming or some other method. As a consequence,
there is not further release of the particles during the
application of the E-coat at stage 14 with a substantially
improved finish at the end of the process.
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Figure 3 is intended to show that the placement of the
additional oven 18 does not necessarily have to follow the step -
12 of metal finishing but may precede such step. In Figure 3, the
oven 18 follows immediately after the welding an soldering 10,
11.
The actual se~uence of the entire method is not important as ~:
long as there is the step of heat treatment following the welding
and soldering but preceding the step of pho~phate treatment and
preferably preceding the step of metal finishing.
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It will thus be appreciated that many other embodiments of
the present invention may exist whioh may differ in detail from
the sequence described and shown in the drawings, without
departing from the scope of the present invention. Accordingly, I
wish to secure by letters patent document i~sued on this
application all such embodiments as properly fall within the
scope of my contribution to the art.
