Abstract:
A mount assembly system provides repeatable net position of vehicle body mounts, enabling an automated body to frame marriage process. With the system, a body mount bracket is assembled to the vehicle&#39;s frame rail and the body mount is relocatably attached thereto. Prior to tightening the mount, a positioning fixture engages the mount, repositioning it to a desired location.

Description:
TECHNICAL FIELD 
     The present invention relates to a mount assembly system and more particularly, to a system for providing repeatable net position of body mounts, facilitating the automation of a vehicle body and frame marriage process. 
     BACKGROUND OF THE INVENTION 
     One of the most impressive operations in a vehicle assembly plant involves the marriage of a vehicle body structure to its chassis. Commonly used methodology involves a substantial reliance upon manual intervention to accomplish this complex task. Automating this type of vehicle assembly process is highly desirable due to the labor intensive and physically demanding operations involved. Automation is complicated by factors like the stack-up of build tolerances that occurs as components are assembled together. In the case of body on frame vehicles including medium and heavy duty trucks, a number of unique frame assemblies with different rail spacing widths or different frame rail material properties may be employed for various GVW applications. A desire to marry the resulting variants to a common body design further complicates automation. 
     During the marriage process, body mounts are commonly manually aligned to enable assembly of the bolts that secure the body to the frame. Attempts at automation of the marriage process have been made by using means such as “post-piercing” of the assembled frame before marriage. This is somewhat of a limited solution since it is rather costly and is not universally employable, especially in vehicles with large ladder-type frames. Accordingly, advances in component design that facilitate marriage automation in a cost-effective manner are needed. 
     SUMMARY OF THE INVENTION 
     Aspects of the invention reside in a generic mount assembly system that facilitates the automated marriage of a pair of mating components or assemblies through the interposed mount. Depending on the specific application involved, the intended advantages include: providing repeatable net positioning, avoiding part number proliferation, overcoming build-tolerance stack, and improving operator working conditions. The resultant aspects are achieved through employment of a mount alignment feature that operates to position the mount(s) during their assembly onto one of the to-be-mated components or assemblies. 
     With more specificity, a mount assembly system includes a first component or assembly with a mount fastened thereto in an initially repositionable manner, wherein the mount moves relative to the component or assembly in concert with a repositioning element. The repositioning element includes a positioning feature that is engageable by a positioning fixture to effect proper alignment to a repeatable net position selected for the later introduction of a second component or assembly that will arrive at a predetermined point in space coinciding with said repeatable net position for marriage of the first and second components or assemblies together. 
     A preferred exemplary embodiment of the present invention described here as an aid in readily conveying the nature of the invention, enables automated assembly of a truck body to its frame and includes a frame having a pair of brackets on opposed sides thereof. The brackets support the body on the frame, through an interposed body mount. During assembly, the frame and brackets accept a pair of body mounts in a repositionable manner whereupon, a positioning fixture engages the frame and engages repositioning elements of the mounts to align the body mounts, which are then fixed in place on the brackets relative to the frame. In this case the positioning fixture includes a pin as a repositioning effector that engages within positioning orifices that have previously been provided in a fixed position relative to the body mount. 
     The numbered claims found at the conclusion of this specification particularly and distinctly define the subject matter of the invention per se. As is typical, the claims are presented to cover a range of inventive breadth, and may have evolved through the give-and-take process of patent examination. The preceding summary of the invention is intended to be consistent therewith, and any inconsistencies are to be resolved by giving governing weight to the language of the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described by way of example, with reference to the accompanying drawings in which: 
     FIG. 1 is a fragmentary perspective view of a mount assembly system according to the present invention, shown partially exploded. 
     FIG. 2 is a fragmentary perspective view of a mount assembly system according to the present invention, shown partially exploded. 
     FIG. 3 is a fragmentary perspective view of a mount assembly system according to the present invention, shown partially exploded. 
     FIG. 4 is a fragmentary cross sectional view of the mount assembly system of FIG.  2 . 
     FIG. 5 is a fragmentary cross sectional view of the mount assembly system of FIG. 2 with the positioning fixture in a pre-engagement location. 
     FIG. 6 is a fragmentary cross sectional view of the mount assembly system of FIG. 2 with the positioning fixture in an engagement location. 
     FIG. 7 is a fragmentary cross sectional view of the mount assembly system of FIG. 3 with an alternative positioning fixture shown in a pre-engagement location. 
     FIG. 8 is an alternative centering mechanism for the positioning fixtures of FIGS.  5 - 7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, FIG. 1 illustrates one side of a vehicle&#39;s mount assembly system  10 . The vehicle&#39;s frame rail  11  comprises an open-section channel having a substantially vertical wall  12  that supports a body mount bracket  14  through a plurality of fasteners  15 . Typically, the spacing width between the vehicle&#39;s left and right frame rails and the material thickness used in the rails will be provided in a number of variants chosen for different end uses of the vehicles. Body mount bracket  14  is a metal stamping having typical structural elements for added rigidity and includes a substantially horizontal platform  16  positioned slightly away from the frame rail  11 . A rib  19  is formed as one piece with the body mount bracket  14  and extends between the vertical leg  20  and the platform  16  leaving a sizable wedge-shaped void  21  between the body mount bracket  14  and the frame rail  11 . The void  21  facilitates the repositioning operation described below. The platform  16  includes a central opening  17  surrounded by a plurality of smaller satellite openings  18 , the congregation existing near the terminal end  22  and across the void  21  from the frame rail  11 . A notch  23  is formed in terminal end  22 , at a position that is outboard from the central opening  17 . 
     A resilient body mount  24  is constructed from metal and an elastomeric material of a specific durometer rating chosen for the application, and includes a generally cylindrically shaped core having a mounting hole  29  extending therethrough. The body mount  24  includes an integral plate  25  with a set of holes  26  spaced to align with the openings  18  of the bracket  14  and being elongated to allow repositioning of the body mount  24  relative to the bracket  14 . Additionally, a positioning orifice  27  extends through a lobe  28  of the plate  25  in a position chosen to align with notch  23  of bracket  14  and serves as the positioning feature of a repositioning element in this case. The positioning orifice  27  is optionally provided in a lobe of any substantially rigid component of the body mount  24 . The body mount  24  is configured to be fastened to the bracket  14  by a plurality of fasteners  30 , which can optionally be integrated into the plate  25 . Initially, the body mount  24  is loosely attached to the bracket  14 , so that it is movable, and once positioned relative to the outer surface of the rail  11 , the fasteners  30  are torqued. 
     Referring to FIG. 2, further details of the repositioning system are shown. The bracket  14  receives the core of the body mount  24  through the central opening  17  so that the plate  25  rests on the platform  16 . The central opening  17  is sized to allow movement of the body mount  24  in the direction of adjustment. The elongated holes  26  align with the openings  18 . Initially, the fasteners  30  are loosely threaded into the openings  18  and extend through the holes  26 . Positioning fixture  32  includes a repositioning effector in the form of pin  35 , and operates to position the body mount  24  before the fasteners  30  are tightened. The positioning fixture  32  includes a depending arm  33  that includes an outwardly tapering segment  34  that operates to help automatically center the fixture relative to the frame rail  11  as it is lowered into engagement therewith. As this occurs, the tapered tip of the pin  35  enters positioning orifice  27  and as the pin in inserted, the taper repositions the body mount  24  to the preferred position relative to the frame rail  11 . The arm  33  enters the void  21  formed between the vertical wall  12  and the rib  19 . The positioning orifice serves to later receive a drift pin (not shown) which locates the nutrunner when the body mount bolt is torqued, and also performs the final location of the body to the frame. 
     FIG. 3 shows an alternative embodiment of the invention wherein the plate arrives as a separate element from the body mount  37 . In this assembly, the openings  38  are elongated and the fasteners  39  extend through openings  40  in the body mount  37 , openings  38  in bracket  41 , and into openings  42  of plate  36 . Elongation of the openings  38  and the central opening  17  permits repositioning of the body mount  40  relative to the frame rail  43 . Initially, the body mount is loosely connected to the bracket  41  along with the plate  36  by the fasteners  39 . Subsequently, the body mount  37  is repositioned by the positioning fixture  44  by engagement of the pin  45  in the positioning orifice  46 . The body mount is subsequently positioned by virtue of a tightly toleranced fit to the plate  36 . After the body mount  37  is properly located, the fasteners  39  are tightened. 
     FIG. 4 illustrates the system of FIG. 1 in an assembled state. The body mount  24  is positioned and fixed to the bracket  14  by the fasteners  30 . The vehicle body  50  is attached to the mount  24  by a bolt  51  that extends through the body mount  24  and is threaded into the body  51  by a nutrunner  52 . The plate  25  remains a part of the final assembly. A drift pin  47  is also shown, which extends through the opening  46  and into the body  50 , locating the body relative to the frame. 
     FIG. 5 shows the positioning fixture  32  in greater detail and discloses that the mounts  24 ,  24 ′ on both sides of the frame are positioned simultaneously. The locating pins  35 ,  35 ′ are carried by the positioning fixture at a fixed distance apart from one another, that is selected to effect the placement of the mounts  24 ,  24 ′ to a position corresponding to the spacing of the mounting holes  49  in the body  50  (as shown in FIG.  4 ). The pins  35 ,  35 ′ and as a result, the body mounts  24 ,  24 ′, are centered relative to the frame rails  11 ,  11  ′ by the centering mechanism  54  of the positioning fixture  32 . Centering mechanism  54  includes a pair of arms  33 ,  33 ′ that are movable in opposing directions and in concert with racks  57  and  57 ′ which are engaged through a pinion  58  of a shaft  59  that is journaled at a fixed point in positioning fixture  32 . The shaft  59  includes a rotating mechanism, in this case a hand crank  60 . As shown in FIG. 6, when the positioning fixture  32  is lowered onto the rails  11 ,  11 ′, the pins  35 ,  35 ′ extend through the positioning orifices  27 ,  27 ′. As the shaft  59  is rotated, the arms  33 ,  33 ′ pull tight against the vertical walls  12 ,  12 ′ centering the positioning fixture  32  relative to the frame rails  11 ,  11  ′ and positioning the mounts  24 ,  24 ′. After positioning, the fasteners are tightened to fix the mounts  24 ,  24 ′ in position and the positioning fixture  32  is retracted to allow for marriage of the body to the frame. 
     FIG. 7 shows an alternative embodiment of the positioning fixture designated  62 , wherein the shaft  69  is rotated by a drive unit  70  that is responsive to electronic control for centering the positioning fixture  62 . This illustration also shows assembly of the mounts  37 ,  37 ′ of FIG. 3, to the frame. FIG. 8 shows an alternative device for relocating the arms  33 ,  33 ′ and includes a crank mechanism operated by shaft  69  to center the positioning fixture. The specific mechanism used and the drive means therefor, may be varied widely within the context of the present invention. 
     Thus, the invention has been described in a typical manner by referencing at least one specific embodiment of the many that are possible for providing repeatable net positioning of body mounts while avoiding part number proliferation, overcoming build-tolerance stack, and improving operator working conditions. The system of mount alignment operates to position the mount(s) onto the vehicle frame prior to the body to frame marriage operation of a vehicle assembly process and is applicable to the alignment of many types of mounts prior to assembly of two components that are mated through a mount. Bearing in mind that it has often been stated, and is generally recognized, that the claims of a patent constitute part of one of the most difficult legal instruments to draw with accuracy; the following claims define the invention and all of its possible embodiments.