The technical field of this disclosure is punches used to form clinch joints in sheet metal parts.
Assembly operations for joining aluminum parts and mixed metal parts are being developed to maximize the use of lightweight parts and improve fuel economy. Currently, self-piercing rivets are used to join aluminum and mixed metal part assemblies because they can provide a strong joint between adjacent parts. Self-piercing rivets add weight to the assembly and also add cost that is added to the final product.
Clinch joints are used in some applications but are not as strong as self-piercing rivet joints, particularly in the coach peel orientation. Clinch joints are lighter weight and less expensive than self-piercing rivet joints because they do not require a rivet Clinch joints are not as strong or robust as self-piercing rivets because they are limited by the extent of mechanical interlock that can be achieved between the joined panels.
The above problems and challenges and others are addressed by this disclosure as summarized below.
This disclosure provides a new clinch joint punch and a new method of forming a clinch joint that increases the extent of mechanical interlock for clinch joints. Increasing the mechanical interlock results in higher joint strength. The total number of clinch joints in an assembly having multiple clinch joints may be reduced because the strength of each clinch joint is increased.
According to one aspect of this disclosure, a clinch punch is disclosed for joining multiple panels with a clinch joint. The punch comprises a core having a first cam surface and an sleeve defining an opening. The sleeve has a plurality of teeth that each includes a second cam surface. An actuator drives the core and sleeve into a plurality of panels. The core is moved within the sleeve by the actuator with the first cam surface engaging the second cam surfaces to move the teeth outwardly to join the panels together.
According to other aspects of the punch, a spring may operatively engage the core and the sleeve to bias the core away from the panels and disengage the first cam surface from the second cam surfaces to move the teeth inwardly to retract the punch from the panels. The core may have a head on a first end that is engaged by the actuator and the spring may be disposed between the sleeve and the head with the spring being compressed as the teeth are moved outwardly and expanded as the teeth are moved inwardly.
The core may be a cylindrical member having a leading end that includes a partially conical surface and the second cam surfaces on the teeth may each have a contact surface that is disposed at a complementary angle to the first cam surface.
Alternatively, the sleeve may include a plurality of separate jaws that are retained on the core by a connector that secures the jaws to the core. The connector may be attached to the core with a lost motion connection that allows the core to move to a limited extent relative to the jaws. The connector may be a fastener and the jaws may each define an opening that receives the fastener and the core may define a slot that is elongated in a direction that the core is moved by the actuator.
The punch may further comprise a spring operatively engaging the jaws to bias the jaws toward the core, and wherein the jaws are driven apart by the first cam surface engaging the second cam surfaces. The spring may be a first spring attached to a first end of the fastener and a second spring attached to a second end of the fastener. The first and second springs bias the teeth toward the core with the first cam surface engaging the second cam surface to move the teeth away from the core.
According to another aspect of this disclosure a method is disclosed for forming a clinch joint in a plurality of panels. The method comprises driving a punch assembly including a core and an sleeve having a plurality of teeth into the panels to form a depression in the panels. The teeth are shifted outwardly within the depression in the panels to mechanically interlock the panels.
According to other aspects of the method, the core may have a first cam surface and the sleeve may have a second cam surface and the method may further comprise engaging the first cam surface and the second cam surface to shift the teeth outwardly. The teeth may be projections that extend in a longitudinal direction from the sleeve. The second cam surface may further comprise a plurality of second cam surfaces that are each provided on one of the teeth.
According to an alternative embodiment of the method, the sleeve may further comprise a plurality of jaws that each includes at least one of the plurality of teeth and one of the second cam surfaces.
The method may further comprise shifting the teeth inwardly after mechanically interlocking the panels, and retracting the punch assembly from the depression in the panels. The core may have a first cam surface and the sleeve may have a second cam surface. The method may further comprise engaging the first cam surface and the second cam surface to shift the teeth outwardly, and withdrawing the first cam surface from the second cam surface to shift the teeth inwardly.
The above aspects of this disclosure and other aspects are described in greater detail below with reference to the attached drawings.
A detailed description of the illustrated embodiments of the present invention is provided below. The disclosed embodiments are examples of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale. Some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed in this application are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art how to practice the invention.
Referring to
Referring to
The head 28 is provided on an inner end 30 of the core 22. The inner end 30 is received and retained in a clinch joint tool (not shown). A cam surface 32 that is a frusto-conical surface is provided at a distal end 34 of the core 22.
The sleeve 24 includes a plurality of fingers 36 that are provided at a leading end 38 of the sleeve 24. A plurality of cam surfaces 40 are provided on each of the fingers 36. The cam surfaces 40 are disposed at a complementary angle to the cam surface 32 of the core 22. Forming surfaces 42 are provided on an outer surface of the fingers 36. The forming surfaces 42 engage the clinch joint 10 in the final stages of forming the clinch joint.
Referring to
Referring to
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The head 72 of the core 52 receives the actuation force A1 and drives the core downwardly, as illustrated. A driving cam surface 74 provided on the core 52 engages the driven cam surface 76 that is provided on the first jaw 54 and second jaw 56.
Referring to
While two jaws 54 and 56 are shown, it is anticipated that four or more jaws could be provided with suitable modifications of the clinch punch 50.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosure. The words used in the specification are words of description rather than limitation. Changes may be made to the illustrated embodiments without departing from the spirit and scope of the disclosure as claimed. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts.
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Number | Date | Country | |
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20150101170 A1 | Apr 2015 | US |