Obviousness — US Patent 11885358

Obviousness Analysis under 35 U.S.C. § 103 for US Patent 11885358

This analysis considers combinations of prior art references that would render the independent claims of US Patent 11885358 obvious to a person having ordinary skill in the art (POSA). The primary goal of US11885358 is to provide a blind fastener and installation method that reduces installation forces and increases corrosion resistance, specifically by utilizing a mandrel that does not fracture during installation. [cite: US11885358 Description, paragraph 0038]

Independent Claim 1: Blind Fastener

Claim 1 describes a blind fastener comprising:

A sleeve with first and second ends and a cavity.
A mandrel at least partially received by the cavity, comprising:
- A first mandrel end adjacent to the first sleeve end, having an enlarged portion with a diameter greater than the cavity's diameter.
- A second mandrel end with a pull region.
- A shank region intermediate the first and second mandrel ends.
A crucial limitation: the pull region comprises an axial length no greater than 4 times a diameter of the shank region and is configured to be engaged by an installation tool.

Combination of Prior Art: US7293339B2 in view of general knowledge in the art of blind fastener design.

Primary Reference: US7293339B2 (Huck International, Inc.)
US7293339B2, titled "Low swage load fastening system and method," discloses a two-piece blind rivet comprising a pin (mandrel) and a sleeve that are permanently interlocked without requiring the pin to break off. [cite: US7293339B2 Abstract] This directly addresses the stated objective of US11885358 regarding a non-frangible mandrel and the associated benefits of reduced installation shock and forces ("low swage forces"). [cite: US7293339B2 Abstract]

Let's break down how US7293339B2 teaches the elements of Claim 1:

Blind fastener comprising a sleeve and a mandrel: US7293339B2 explicitly describes a "two-piece blind rivet having a pin and a sleeve." [cite: US7293339B2 Abstract] The sleeve (20) has a bore (28) acting as a cavity, and the pin (10) serves as the mandrel. [cite: US7293339B2 Figure 1]
Sleeve with first and second ends and a cavity: The sleeve (20) has a head (22) and a blind end (24) (which would correspond to the second and first sleeve ends, respectively, based on the installation described). A cavity (bore 28) extends through it. [cite: US7293339B2 Figure 1]
Mandrel at least partially received by the cavity: The pin (10) is clearly shown received within the bore (28) of the sleeve (20). [cite: US7293339B2 Figure 1]
First mandrel end adjacent to the first sleeve end, having an enlarged portion with a diameter greater than the cavity's diameter: The pin (10) has a pull-up section (14) which functions as an enlarged portion, disposed adjacent to the blind end (24) of the sleeve (the first sleeve end in the context of installation). This pull-up section (14) has a diameter greater than the cavity's diameter (bore 28). [cite: US7293339B2 Figure 1, column 3, lines 17-20]
Second mandrel end with a pull region: The pin (10) includes a pull portion (12) with pull grooves (16) at its second end, configured to be engaged by an installation tool. [cite: US7293339B2 Figure 1, column 3, lines 17-20]
Shank region intermediate the first and second mandrel ends: The pin (10) has a shank (18) extending between the pull-up section (14) and the pull portion (12). [cite: US7293339B2 Figure 1, column 3, lines 17-20]

Missing Element: The explicit limitation that the pull region comprises an axial length no greater than 4 times a diameter of the shank region.

Motivation for a POSA to Combine/Modify:
A person of ordinary skill in the art (POSA) designing blind fasteners, and specifically aiming for the "low swage forces" and non-break-off characteristic taught by US7293339B2, would be motivated to optimize the dimensions of the pull region. The length of the pull region is a known design parameter that affects material usage, gripping effectiveness of the installation tool, and the overall force required during installation.

The specification of US11885358 itself describes the pull region's axial length as "no greater than 4 times a diameter of the shank region, such as, for example, no greater than 3.8 times... or no greater than 1 times the diameter." [cite: US11885358 Description, paragraph 0056] This wide range suggests that various lengths within this limit are contemplated and represent routine design choices. A POSA, seeking to further reduce material costs, improve tool compatibility, or finely tune the installation forces of the fastener described in US7293339B2, would find it obvious to adjust the axial length of the pull portion (12) to be no greater than 4 times the diameter of the shank (18). This would be a predictable modification based on known engineering principles and without requiring inventive ingenuity, especially when the underlying goals of reduced force and an intact mandrel are already present in US7293339B2.

Obviousness of Dependent Claims of Claim 1:

Claims 2 & 3 (shorter axial lengths): These claims specify narrower ranges for the pull region's axial length (no greater than 3.8 or 2 times the shank diameter). As discussed, choosing a specific length within a known effective range, particularly for material savings or further force optimization, constitutes a routine design choice for a POSA.
Claim 4 (taper): The pull region comprising a taper or reverse taper is a common feature in blind fasteners to facilitate the engagement and disengagement of an installation tool's collet. A POSA would be motivated to incorporate such a taper into the pull region of US7293339B2 to enhance the efficiency and smoothness of the installation process, consistent with the objective of achieving "low swage forces."
Claim 5 (no breakneck groove): This feature is explicitly taught by US7293339B2, which states the pin is "permanently interlocked to each other without requiring a break-off of the pin." [cite: US7293339B2 Abstract]
Claims 6 & 7 (Rockwell hardness): Specifying a particular Rockwell hardness for the mandrel is a material selection choice, routinely made by a POSA based on the desired strength and performance requirements of the fastener for a given application. US7293339B2 indicates that the pin can be made of steel, a material commonly heat-treated to achieve various hardness levels.
Claims 8 & 9 (features on shank/pull region): US7293339B2 shows pull grooves (16). [cite: US7293339B2 Figure 1] Other features such as threaded regions or annular shoulders on the shank or pull region are common in various fastener designs for purposes like grip range, vibration resistance, or specialized tool engagement, and would be obvious alternatives or additions for a POSA.
Claims 10 & 11 (cylindrical shapes, materials): The generally cylindrical shapes of the sleeve and mandrel, and the use of metal, metal alloys, or composite materials, are inherent and widely known aspects of blind fastener construction, as taught by US7293339B2 (e.g., steel pin and sleeve) and general prior art.
Claims 12-15 (installation in a bore, deformation, swaging, application): These claims relate to the functional aspects and application of a blind fastener. US7293339B2 describes the installation in a workpiece (structure) and the deformation (forming a blind head) and swaging processes. [cite: US7293339B2 Abstract, column 4, lines 1-10] The applications (aerospace, automotive, etc.) are standard uses for such fasteners.

Independent Claim 16: Method for Fastening

Claim 16 describes a method for fastening using a blind fastener (as defined in Claim 1), comprising the steps of:

Inserting a first mandrel end of the blind fastener into a bore in a structure.
Engaging a collet of the installation tool with the pull region.
Forcibly contacting the second sleeve end with an anvil of the installation tool and moving the pull region distal from the second sleeve end.
Deforming the sleeve on a first side of the structure and swaging the second sleeve end onto the shank region on an oppositely disposed second side of the structure, thereby securing the fastener.

Combination of Prior Art: US7293339B2 in view of general knowledge of blind fastener installation methods.

Primary Reference: US7293339B2 (Huck International, Inc.)
US7293339B2 teaches a method of installing its blind rivet where the pin (mandrel) is pulled relative to the sleeve to form a blind head and swage the sleeve. [cite: US7293339B2 Abstract, column 4, lines 1-10] The "low swage load fastening system and method" inherently encompasses the goal of reduced installation forces. [cite: US7293339B2 Abstract]

Let's evaluate the method steps against US7293339B2:

Inserting a first mandrel end of a blind fastener into a bore in a structure: This is the fundamental first step for installing any blind fastener, including that described in US7293339B2. The pin (mandrel) would be inserted through the workpiece (structure) bore.
Engaging a collet of the installation tool with the pull region: The pull portion (12) of the pin (10) in US7293339B2 is described as having "pull grooves 16 formed thereon so that an installation tool may grip the pin 10" [cite: US7293339B2 column 3, lines 18-20]. The use of a collet for gripping the pull region of a blind fastener is standard and well-known in the art of blind fastener installation.
Forcibly contacting the second sleeve end with an anvil of the installation tool and moving the pull region distal from the second sleeve end: This is the conventional mechanism for installing pull-type blind fasteners. The anvil of the installation tool typically reacts against the head of the sleeve (second sleeve end), while the collet pulls the mandrel (pull region) away. This process is implicitly described and understood from the mechanism of blind rivet installation in US7293339B2 to achieve the stated "low swage load."
Deforming the sleeve on a first side of the structure and swaging the second sleeve end onto the shank region on an oppositely disposed second side of the structure, thereby securing the fastener: US7293339B2 explicitly describes the pin (mandrel) pulling its enlarged portion into the sleeve to expand it into gripping engagement, thereby forming a blind head (deformation on the blind side). It also describes a collar on the sleeve being "simultaneously swaged into the stem of the pin" against the outer surface of the workpiece. [cite: US7293339B2 Abstract, column 4, lines 1-10] These actions directly correspond to the deforming and swaging steps of Claim 16, securing the fastener in the structure.

Missing Elements: The specific axial length limitation of the pull region (no greater than 4 times a diameter of the shank region) as an explicit step in the method.

Motivation for a POSA to Combine/Modify:
The method steps described in Claim 16 are standard and inherent to the installation of a blind fastener that achieves permanent interlock without mandrel break-off, as taught by US7293339B2. A POSA would routinely use an installation tool comprising a collet and an anvil to perform the pulling and reacting forces necessary for such a fastener. The specific dimensions of the pull region, as discussed for Claim 1, would be optimized design choices within the context of this known installation method to achieve the desired "low swage load" and efficient tool operation. The selection of a pull region length no greater than 4 times the shank diameter would be an obvious choice for a POSA, given the benefits already inherent in the US7293339B2 system.

Obviousness of Dependent Claims of Claim 16:

Claims 17-20: These dependent claims incorporate features of the blind fastener itself (e.g., pull region length, taper, no breakneck groove, materials). As argued above, these features are either explicitly taught by US7293339B2 or are obvious design choices and modifications that a POSA would apply to the fastener used in the method of US7293339B2.

Conclusion

Both independent claims (Claim 1 and Claim 16) of US11885358 would likely be considered obvious under 35 U.S.C. § 103 over US7293339B2 in combination with the general knowledge of a person having ordinary skill in the art of blind fastener design and installation. US7293339B2 teaches the core inventive concept of a blind fastener system with a non-frangible mandrel and reduced installation forces. The specific axial length limitation of the pull region, the presence of a taper, and other details are routine design optimizations or common elements in the art that a POSA would be motivated to incorporate to enhance the performance and manufacturing efficiency of the fastener described in US7293339B2.