Method for manufacturing a side rail for a vehicle frame assembly

A method for manufacturing a side rail in a vehicle frame assembly includes the initial step of roll forming flat stock to form a side rail having a C-shaped cross section defined by an upper flange corresponding to the top open side of the C-shape, a lower flange corresponding to the bottom or opposite open side of the C-shape, and a web corresponding to the back of the C shape and connecting the upper flange and the lower flange. The terminal edges of the upper flange and the lower flange define an edge plane that extends generally parallel to a vertical plane defined by the web. A portion of the lower flange is then stamped in a direction parallel to the vertical plane to form a kick-up in portion in the lower flange. The edge plane defined by the edges of the upper and lower flanges in the kick-up portion does not extend at the predetermined relationship relative to the plane defined by the web. Then, a portion of the lower flange in the kick-up portion is removed, such as by trimming with a cutting torch, such that the edge plane defined by the edges of the upper and lower flanges in the kick-up portion again extends at the predetermined relationship relative to the plane defined by the web.

BACKGROUND OF THE INVENTION 
This invention relates to methods for manufacturing vehicle frame 
components. More specifically, this invention relates to an improved 
method for manufacturing a side rail for use in a vehicle frame assembly. 
Most land vehicles in common use, such as cars and trucks, use a frame that 
serves as a platform upon which the remainder of the vehicle is built. 
Many vehicle frame structures are known in the art. Most known structures 
are formed from a number of individual metallic components that are 
permanently joined together. For example, a typical perimeter vehicle 
frame assembly is composed of a pair of longitudinally extending side 
rails that are joined together at the front and rear by a pair of 
transversely extending cross members. Additional connections between the 
side rails are made at intermediate locations using one or more 
intermediate or auxiliary cross members. The cross members not only 
connect the two side rails together, but also provide desirable lateral 
and torsional rigidity to the vehicle frame assembly. 
In some vehicle frame assemblies, the side rails and cross members are 
formed from open channel structural members, i.e. structural members that 
have a non-continuous cross sectional shape. A typical open channel 
structural member is C-shaped in cross section. In a frame assembly, such 
a structural member is positioned so that the open legs of the "C", called 
the upper and lower flanges, are essentially parallel to the ground. The 
upper and lower flanges are connected to each other by a web (the back of 
the "C"). The web forms a plane that is perpendicular to the ground. In an 
open channel structural member, the edges of the flanges define a plane 
that is parallel to the plane defined by the web. 
For certain vehicle applications, it is desirable to deform a portion of 
the side rail to provide a deformation or kick-up portion in one of the 
flanges. This kick-up portion provides clearance for vehicle components, 
such as a rear axle and drive train assembly. It is often desirable that 
the side rail have a kick-up in a portion of the lower flange only and the 
upper flange remain straight. 
To manufacture a C-shaped open channel structural member, an elongated flat 
steel stock is stamped to the desired shape. For example, it is known to 
form a C-shaped member as a structural component for vehicle frames 
including an upper flange that extends horizontally the length of the side 
rail, and a lower flange that extends horizontally the length of the rail, 
except for the kick-up portion. The edges of these flanges form a plane 
that is parallel to the plane defined by the web. 
In order to stamp C-shaped members of the required length, particularly for 
use in sport utility vehicles, vans, and trucks, relatively long dies that 
extend the total length of the side rail are required. Unfortunately, a 
large industrial press must be used to handle such long dies. And the 
formation of side rails of different configurations for different vehicles 
requires multiple dies. Although the technology of stamping using large 
dies and presses is well known, the scale makes the overall process 
expensive. Thus, it would be desirable to provide a method of 
manufacturing C-shaped structural members for use as side rails in vehicle 
frames that is less expensive than a large scale stamping operation. It 
would also be desirable to provide a method of manufacturing C-shaped 
structural members for use as side rails that is easily scalable to 
different vehicle sizes. 
SUMMARY OF THE INVENTION 
This invention relates to a method for manufacturing a side rail in a 
vehicle frame assembly. Initially, flat stock is roll formed to form a 
side rail with a C-shaped cross section having an upper flange 
corresponding to the top open side of the C-shape, a lower flange 
corresponding to the bottom or opposite open side of the C-shape, and a 
web corresponding to the back of the C shape and connecting the upper 
flange and the lower flange. The outer edges of the upper flange and the 
lower flange define a plane that extends parallel to a vertical plane 
defined by the web. A portion of the lower flange is stamped in a 
direction parallel to the vertical plane to form a kick-up in the lower 
flange. The kick-up has a protruding edge extending beyond the edge plane. 
This protruding edge is then trimmed so as to extend flush with the plane 
defined by the outer edges of the upper flange and the lower flange as 
originally formed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The formation of a side rail for a vehicle frame assembly in accordance 
with this invention starts with a length of flat stock 10, as shown in 
FIG. 1. This flat stock 10 can be any material that can be roll formed and 
stamped that is suitable for a vehicle frame. For example, the flat stock 
10 can be formed from steel or steel alloys. The length of this flat stock 
10 preferably corresponds generally to the length of the side rail for the 
vehicle frame, but can be any convenient length. The flat stock 10 has a 
pair of longitudinal edge portions 12 and a longitudinally extending 
central portion 14. 
FIGS. 2 and 3 illustrate the next step in forming a side rail in accordance 
with this invention. First, as shown in FIG. 2, the edge portions 12 are 
bent or formed throughout the length of the flat stock 10 so as to extend 
at an angle with respect to the central portion 14. In the roll forming 
process illustrated in FIGS. 2 and 3, the flat stock 10 is fed through a 
series of spaced apart rollers 16 to accomplish this. Preferably, a series 
of opposed pairs of rollers 16 are positioned on opposed sides of the edge 
portions 12 of the flat stock 10. The pairs of rollers 16, adjacent to one 
another along the feed direction, are positioned at an offset 
relationship. When the flat stock 10 is fed through the series of rollers 
16, the edge portions 12 are forced to conform to the positioning of the 
rollers 16. The series of rollers 16 are positioned so that the initially 
flat length of stock 10 is progressively formed into an elongated 
channeled side rail 18 having a generally C-shaped cross section, as shown 
in FIG. 3. 
As shown in cross section in FIG. 3, the formed side rail 18 has a 
horizontally extending upper flange 20 and a horizontally extending lower 
flange 22 that are connected together by a vertically extending web 24. 
The upper and lower flanges 20 and 22 are formed from the edge portions 12 
of the stock 10, and the web 24 is formed from the central portion 14 of 
the stock. The upper and lower flanges 20 and 22 terminate in 
longitudinally extending edges 20a and 22a that define a vertical plane 26 
that extends parallel to the vertical plane defined by the web 24. Thus, 
the widths of the upper and lower flanges 20 and 22 are approximately 
equal along the length of the side rail 18. Preferably, the side rail 18 
is roll formed so that the upper and lower flanges 20 and 22 extend at 
right angles with respect to the web 24. 
After the C-shaped side rail 18 is formed, a kick-up portion 28 is formed 
in the lower flange 22 and a portion of the web 24 of the side rail 18, as 
shown in FIG. 4. The kick-up portion 28 is formed by stamping the side 
rail 18 in such a manner that the upper flange 20 continues to extend 
horizontally throughout the entire length of the side rail and the lower 
flange 22 extends horizontally the entire length of the side rail except 
for the kick-up portion 28, as shown in FIG. 6. The function of the 
kick-up portion 28 is to provide clearance for components, such as an axle 
32, positioned beneath the side rail 18 of the finished frame. 
To stamp the kick-up portion 28, only a localized area (indicated by the 
region "A" in FIG. 6) of the side rail 18 needs to be stamped. Thus, the 
die(s) required to form the kick-up portion, and the stamping press, can 
be relatively short compared to the total length of the side rail 18. 
Also, the same die may be used for forming the kick-up in side rails for 
vehicles using similarly sized axles regardless of the length of the side 
rail 18 for an obvious cost advantage. 
In the area of the kick-up portion 28, the edges 20a and 22a generally 
define a plane 30 that is angled relative to the vertical plane defined by 
the web 24, as shown in FIG. 7. Because of the degree of height in the 
side rail 18 in the area of the kick-up portion 28, the stamping process 
displaces material and forms a protrusion 34 in the lower flange 22. This 
protrusion 34 extends along the length of the edge 22a of the lower flange 
22 adjacent to the kick-up portion 28 as best seen in FIGS. 4, 5, and 7. 
It is generally desirable to have a side rail 18 having an upper edge 20a 
and a lower edge 22a (of the upper flange 20 and the lower flange 22, 
respectively) define a plane that is uniformly parallel along the length 
of the side rail 18 to the plane defined by the web 24, as shown in FIG. 8 
and FIG. 9 (referred to herein as an edge plane). This can be accomplished 
by removing the protrusion 34 by any suitable method, such as with a 
cutting torch. 
It is understood that the C-shape of the invention encompasses a variety of 
open end shapes. Although the upper edge 20a and the lower edge 22a are 
illustrated as being flat planes that join the web at right angles, the 
upper edge 20a, the lower edge 22a, and the web 24 may be somewhat curved 
and define angles other than right angles. Further, the planes defined by 
the web, and the upper edge and lower edge, as discussed above as well as 
the horizontal surfaces of the upper and lower edges are illustrated as 
exactly conforming to their defining surface. In fact, the invention is 
intended to include planes and the horizontal surfaces that are only 
approximations of their defining part. Also, although the edge planes 26 
and 36 defined by the outer edges of the upper and lower flanges 20a and 
22a at the beginning and end of the method extend generally parallel to 
the vertical plane defined by the web 24, it will be appreciated that such 
edge planes 26 and 36 may extend at any desired relationship, parallel or 
non-parallel, relative to the plane defined by the web 24. 
The method of the present invention results in a side rail for a vehicle 
frame that is generally C-shaped defined by a lower flange on the 
underside of the frame and an upper flange on the top side of the frame. 
Both the lower flange and the upper flange extend horizontally the length 
of the side rail. A web, extending as a vertical plane the length of the 
side rail, connects the lower and upper flanges. The lower flange and the 
upper flange each have a longitudinally extending edge, and together these 
edges define an edge plane that is parallel to the vertical plane of the 
web. The upper flange extends horizontally the entire length of the side 
rail. The lower flange extends horizontally the entire length of the side 
rail except for the kick-up portion. As used herein, the term "kick-up" 
refers to any depression in the side rail to accommodate vehicle 
components. This kick-up can be of any size, shape, or configuration 
necessary. 
In summary, the starting material of the invention is a length of stock 
material appropriately sized. This stock is roll formed to create a 
C-shaped piece having a lower flange and an upper flange as described 
above. After this roll formation, both the lower flange and the upper 
flange extend horizontally the entire length of the piece. This piece is 
then stamped to create a kick-up in the lower flange. As a result of the 
material displaced in the stamping, the longitudinal edge of the lower 
flange extends beyond the longitudinal edge of the upper flange. The plane 
thus formed by the longitudinal edge of the lower flange and the 
longitudinal edge of the upper flange intersects the vertical plane formed 
by the web. In order to align the longitudinal edges of the lower and 
upper flanges, the extension of the edge of the lower flange is trimmed so 
that the edge plane formed by the longitudinal edges of the lower and 
upper flanges are aligned with the web. 
In view of the above description, it is obvious that various alternative 
embodiments are possible using variations of the method described above 
without departing from the spirit and scope of the present invention. It 
is intended that the drawings, descriptions, and discussion contained in 
this specification illustrate the present invention rather than limit it. 
It is the following claims, including all equivalents, that define the 
scope of the invention.