US 5,056,953 · Granted 1991-10-15
The Bayonet Lock That Turned Flat-Pack Furniture Into a Global Industry
Imagine furniture that snaps together like building blocks without needing tools or screws. This patent covers a clever locking mechanism with two metal pieces that twist together inside hollow frame bars, gripping panels automatically as they rotate. It's the engineering trick that makes IKEA-style modular furniture actually work.
The plain-English version
What it protects
The claim covers an assembly device consisting of two insertable bodies that fit inside hollow framework bars. Each body has a central locking portion shaped like a sloping ramp (a bayonet coupling) that can penetrate through a hole in a panel. When the two bodies rotate relative to each other, they deform outward and lock automatically against the panel faces. What's protected here is specifically this radial-deformation locking mechanism and the geometry of the sloping ramp coupling that enables it.
Why it matters
This patent represents a fundamental engineering solution to the flat-pack furniture problem: how do you assemble complex modular pieces without fasteners, tools, or expert labor? By removing the need for bolts, screws, or welding, this mechanism enabled mass production of affordable, shippable furniture kits. The simplicity and reliability of the design made it commercially valuable for manufacturers seeking to reduce assembly time and cost while maintaining structural integrity.
Real-world use
Every time you assemble a modular bookshelf, desk, or wall unit from a furniture kit, you're likely using a variation of this locking principle—metal connectors inside the frame bars that grip panels as pieces twist together.
Original USPTO abstract
The invention relates to an assembly device for elements of the type comprising a framework and at least one spacer or panel extending transversely to said framework. In accordance with the invention, the device comprises two assembly bodies (100, 200) insertable in respective hollow bars constituting a portion of the framework, each assembly body having a central locking portion (101, 201) capable of penetrating into a hole in a panel to be supported, together with a peripheral portion (102, 202) capable of bearing against one of the faces of said panel; the central locking portions (101, 201) constitute a sloping ramp bayonet coupling, thereby enabling said bodies to be deformed radially outwards by relative rotation between the two assembly bodies, thus locking them automatically in the associated hollow bars. The invention is applicable, in particular, to pieces of furniture for provision in kit form, and for various types of element and/or hollow bar.
Patent details
- Publication number
- US 5,056,953
- Filing date
- 1989-05-09
- Grant date
- 1991-10-15
- Assignee
- Societe De Design Et D'agencement
- Inventor(s)
- MAROT; JACQUES, BOUE; JEAN-CLAUDE
- CPC class
- A47B87/0246
Want to file your own patent?
If you're designing a new modular furniture concept, search our database to see how existing assembly patents map your space before you prototype your first joint.
Free patentability scan