Patent Application
20160236259
This disclosure is directed to a method and apparatus for punching openings in a tubular part in a hydro-forming tool and installing a nut or other threaded fastener inside the tubular part.
Tubular parts may be formed in a hydro-forming operation performed in a hydro-forming tool. A hydro-formed part may replace multiple conventionally stamped parts in a single part thereby reducing the number of separate parts and process steps required to make an assembly. In addition, hydro-formed parts may provide increased strength and may reduce the weight of a part.
One disadvantage of prior art hydro-formed parts is that fasteners, such as nuts and bolts, must be installed after the hydro-forming operation is complete and the tubular part is removed from the hydro-forming tool. Post hydro-forming operations also add to the cycle time for manufacturing a hydro-formed assembly. Post hydro-forming operations add to the capital equipment cost for making an assembly. Increased cycle times and capital equipment costs add to the cost of manufacturing a hydro-formed assembly.
In addition, attaching fasteners to a hydro-formed part may be a problem if the fasteners must be assembled to meet close tolerances. The hydro-formed part and fasteners may need to be manipulated multiple times to install a nut on or within a tubular part. Installing a nut inside a tubular part is problematic because of the difficulty in locating, retaining and securing the nut inside the tubular member.
This disclosure is directed to solving the above problems and other problems as summarized below.
According to one aspect of this disclosure, a method of making a hydro-formed assembly is provided that includes the following steps. In the first step, a first opening is punched in a first wall of a tubular part with an outer punch. In a second step, a nut is clinched to an inner surface of the second wall of the tubular part and a second opening is punched in a second wall of the tubular part with a clinching feature provided on the nut around a bolt receiving opening defined by the nut.
According to other aspects of the method, an additional step of hydro-forming the tubular part in a hydro-forming tool is performed before the first opening is punched in the first wall. The method may further comprise loading the nut onto a nut retainer disposed within the outer punch before punching the first opening in the first wall.
According to another aspect of this disclosure, a tool for hydro-forming a part is disclosed. The tool comprises a hydro-forming die retained in a hydro-forming tool and a dual action punch operated by the tool. The dual action punch includes an outer punch and a nut retainer disposed inside the outer punch. An annular recess is provided on the die on an opposite side of the part from the dual action punch to facilitate securing the nut to an inner surface of the part. The nut defines a fastener receiving opening and includes a clinching feature disposed around the fastener receiving opening that punches an opening in the part.
According to other aspects of this disclosure as it relates to a tool for hydro-forming a part, the outer punch may form a first opening in a first portion of a wall of the part and the clinching feature on the nut forms a second opening in a second portion of the wall of the part that is axially aligned with the first opening. The nut is retained by the nut retainer within the outer punch while the outer punch forms the first opening in the first portion of the wall. The nut retainer secures the nut to the inner surface of the part by clinching the nut to the inner surface.
The hydro-form tool and die include an opening through which a slug formed by the clinching feature on the nut is removed from the second opening. The hydro-forming die may also define a relief area around the opening that receives material from the part that is displaced when the nut is clinched to the inner surface of the part. Material from the part is also formed around the clinching feature on the nut to retain the nut on the part.
According to another aspect of this disclosure, a punch assembly is disclosed for attaching a nut to a part in a hydro-forming tool. The punch assembly comprises an outer punch for forming a first opening in the part and a nut retainer received within the outer punch for forming a second opening in the part when the nut is attached to the part. The nut has a clinching feature that has a smaller diameter than the outer punch. The receptacle for retaining the nut is coaxially received within the outer punch.
According to other aspects of this disclosure as it relates to the punch assembly, the nut retained by the receptacle may be clinched to the part around the second opening. The outer punch may form the first opening in a first portion of the part and the nut may form the second opening in a second portion of the part. The nut is secured to the second portion in alignment with the second opening. The nut retainer is moveable within the outer punch. The outer punch forms the first opening in the part. The nut held by the nut retainer forms the second opening in the part at a location spaced from the first opening with the first punch engaging the part around the second opening as the nut is clinched to the part.
The above aspects of this disclosure and other aspects are described below with reference to the attached drawings.
The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts.
Referring to
The dual action punch 16 includes an outer punch 18 and a nut retainer 20 that is concentrically received within the outer punch 18. A nut 26 is retained by the nut retainer 20 and includes a clinching feature 22. The clinching feature 22 is a part of the nut and includes a cutting edge that functions as a cutting edge to punch a slug from the part to form a second opening as will be described below. The nut 26 is disposed within a cup-shaped recess 28 defined by the outer punch 18. A shoulder 30 is part of the nut retainer 20 and engages the nut 26. The shoulder 30 exerts a compressive force on the nut 26 to secure the nut 26 to an inner surface of the tubular part 14 by coining or clinching.
The hydro-forming die 12 defines an annular recess, or relief area, at 34. The relief area 34 receives material displaced when the nut 26 is pressed onto the tubular part to retain the nut 26 on the tubular part 14 inner surface. The hydro-forming die 12 defines a slug removal hole 36.
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The nut 26, first opening 40 and second opening 44 are all coaxially aligned. At this point in the process, the tubular part 14 may be removed from the hydro-forming die 12 as a hydro-formed part assembly 48. After completion, the process may be repeated by loading another tubular part 14 into the hydro-forming die 12 and loading a new nut 26 into the dual action punch 16.
No post hydro-forming operations are required to assemble the nut to the tubular part 14. Because the openings 40 and 44 are both punched and the nut 26 is assembled in a single cycle of the dual action punch 16, close tolerances may be maintained as to the relative location of the holes and the nut.
The embodiments described above are specific examples that do not describe all possible forms of the disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and also includes modifications of the illustrated embodiments.
