Quick removable fasteners in particular for furniture

A removable fastener (10, 110) for a part (25, 28, 122) such as a furniture accessory with a hole in a surface (24, 120) comprises a dowel anchor (11, 11', 111) with ribbing thereon (23, 112) for lateral engagement in the surface hole. The dowel anchor comprises a seat (13, 113) in which is received the end of an element (12, 12', 114) in turn constrained to the part and there being between the element and the seat a form of separable mutual constraint. The element is provided in the form of a dowel or pin (12, 12', 114) constrained to the part to be axially insertable in the seat (13, 113) in the dowel anchor and the constraint comprises elastically yielding elements (14, 15, 40, 41, 117) projecting toward the axis of the seat (13, 113) to engage the side wall of the dowel (12, 12', 114) upon its insertion in the seat.

BACKGROUND OF THE INVENTION 
The present invention relates to fasteners for snap fastening and in 
particular for fastening furniture hardware elements such as hinges, 
drawer slides, etc, There are known fasteners comprising dowel anchors to 
be engaged in holes in furniture panels while in said dowel anchors there 
being subsequently engageable fastening screws for hinges, slides, etc. 
In the furniture industry there is an ever growing requirement to reduce 
assembly time for the various components of the furnishings whether during 
assembly at the works or during final installation at the user's site. 
From this viewpoint screw assembly is quite unsatisfactory. There have 
also been proposed faster systems, e.g. with pressure assembly, but which 
are not easy to disassemble, and dovetail systems requiring dedicated 
tools for assembly and disassembly or requiring special handling to 
achieve engagement, which requires a certain skill from the assembler and 
does not permit great speed of assembly. In addition, dovetail systems are 
often relatively costly because of the structural complications they 
involve. 
SUMMARY OF THE INVENTION 
The general purpose of the present invention is to supply economical 
fasteners permitting fast assembly and allowing at the same time easy 
disassembly without the need of special tools or skills on the part of the 
installer. In view of said purpose it is sought to provide in accordance 
with the present invention a removable fastener for a part such as a 
furniture accessory with a surface hole comprising a dowel anchor with 
means of lateral engagement in the surface hole and the dowel anchor 
comprising a seat in which is received the end of a dowel in turn 
constrained to the part and between the element and the seat there being 
present separable mutual constraint means and characterized in that the 
element is provided in the form of a dowel constrained to the part to be 
axially insertable in the seat in the dowel anchor and the constraint 
means comprising elastic yielding elements projecting in the seat to 
engage on opposite sides of the dowel.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to the Figs., FIG. 1 shows a first fastener or joint in 
accordance with the present invention indicated generally by reference 
number 10. The joint 10 comprises a dowel anchor 11 made from relatively 
yielding material and in which engages a connecting dowel 12. As may be 
seen also in FIG. 2, the dowel 12 has a generally cylindrical form with 
one end bearing an enlarged handling head 21, e.g. provided with a 
screwdriver notch. Near the other end, the peripheral surface of the dowel 
has two diametrally opposed notches 26, 27 arranged in a mutually 
symmetrically manner. The insertion end of the dowel can advantageously 
have a taper 22 to facilitate insertion. As may be seen in FIGS. 1, 2 and 
3 the dowel anchor 11 has an axial hole 13 for reception with minimal side 
play of the dowel 12. Optionally the mouth 16 of the hole can have a 
flaring to facilitate insertion of the dowel. In the hole 13 projects a 
pair of facing tabs 14, 15 with free ends inclined toward each other and 
in the direction opposite the opening 16 for insertion of the dowel 12 in 
the bole 13. 
Level with the tabs there are two widened cavities or undercuts 17, 18 
extending at least behind the tabs to permit reciprocal elastic withdrawal 
movement of the tabs. Advantageously for reasons clarified below the end 
part of the dowel bearing the notches or cavities 17, 18 has a smaller 
diameter than the seat or hole 13. As may be seen in FIG. 3 between the 
undercuts 17, 18 there are made two steps 19, 20 with facing surfaces 
which receive with minimal side play the part of the cylindrical dowel 
with smaller diameter so that the dowel is supported for its entire 
length. 
The dowel anchor 11 has advantageously a cylindrical form coaxial with the 
hole 13 and an external side surface with ribbing 23 constituting as 
clarified below means of engagement of the dowel anchor in a suitable hole 
in the assembly surface. For example, the ribbings 23 can be 
circumferential ribbings shaped like an arrow in the direction of 
insertion of the dowel in the anchor. As an alternative there can be 
conceived ribbings arranged helically to form an engagement threading or 
the like. In FIGS. 4 and 5 is shown a possible employment of the above 
described joint to fasten to a surface 24 a hardware element 25. The 
surface 24 can be e.g. a wood panel providing a shoulder or a drawer 
compartment of a furniture item and the hardware element can consequently 
be a guide for the drawers. 
The dowel anchor 11 is inserted, e.g. by pressure, in a complementary hole 
made in the surface 24. The retention means 23 prevent removal of the 
dowel anchor. In the dowel anchor can then be inserted by force the dowel 
12 after it has been passed through a fastening hole of the element 25. As 
may be seen in FIG. 4, by maintaining the notches 26, 27 aligned with the 
tabs, upon complete insertion of the dowel the yielding tabs 14, 15 snap 
out and project into the notches 26, 27. The free ends of the tabs engage 
against the striker surface formed by the wall of the notches and the 
arrow arrangement of the tabs blocks the dowel to prevent is removal. The 
presence of the dowel 12 in the hole 13 also makes the engagement between 
the dowel anchor and the panel 24 stronger while supplying a slight 
expansion of the dowel anchor which is compressed during insertion in the 
complementary hole in the panel. To disassemble the joint it suffices to 
rotate the dowel 12 90.degree. so as to bring its cylindrical surface in 
alignment with the tabs. As may be seen in FIG. 5, the tabs are thus 
pushed radially outward and disengage from the notches to permit easy 
withdrawal of the dowel from its seat in the anchor. Thanks to the smaller 
diameter of the dowel, in its end zone near the tabs the latter are not 
bent excessively outward, thus reducing stress on the material. 
Naturally the dowel head will be formed in accordance with the requirements 
of the piece to be fastened. For example, if it is required that the head 
remain flush with the surface of the fastened piece a dowel with a tapered 
head can be provided as shown in FIGS. 1 to 5. FIG. 6 shows a dowel 12' 
with projecting head, e.g. to fasten a known cup element 28 of a furniture 
hinge. 
As may be seen in FIG. 7 the dowel head has a radial projection 29 which 
interferes with two teeth 30, 31 projecting from the surface of the cup at 
the sides of the hole where the dowel passes. The size of the projection 
and the position of the teeth are such as to permit axial rotation of the 
dowel between an engagement position for the notches with the tabs and a 
disengagement position rotated 90.degree.. As may be seen in FIG. 6 the 
dowel 12' can advantageously have a circumferential groove 32 near the 
head so as to receive a bent edge 33 of the hole passing through the 
element 28 to be fastened. In this manner the dowel is free to rotate but 
remains axially constrained to the element to be fastened thus speeding up 
assembly. It is clear that the head of the dowel can also have different 
means of gripping for handling thereof and not necessarily a notch for a 
blade or cross screwdriver. For example, there can be provided an 
engagement for a hexagonal wrench or projections for manual handling 
without tools. 
As shown in FIG. 6 the dowel anchor can have an edge 37 projecting 
circumferentially to the insertion end of the dowel to prevent excessive 
penetration of the dowel anchor in the engagement surface. 
There can of course be imagined other means of constraining the engagement 
dowels with the piece to be fastened. For example, FIG. 8 shows an 
engagement pin 12" provided in two parts. A first part 34 has a form 
similar to that of the legs of the dowels described above while a second 
part 35 consists of a screw which screws into a threaded hole axial with 
the stem 34. It is thus easy to place between the screw and the stem an 
element 36 to be fastened. The thread of the screw can be provided of a 
length such as to permit mutual locking between the screw and the stem 
without preventing their rotation in the passing hole in the element. 36. 
Naturally the above description of an embodiment applying the innovative 
principles of the present invention is given merely by way of example and 
therefore is not to be taken as a limitation of the patent right claimed 
here. For example, the radial elastic engagement means of the dowel anchor 
can be provided in a different manner from elastic tabs 14, 15 in a single 
piece with the dowel anchor. For example, FIGS. 9, 10 and 11 show a 
possible variation in which the dowel anchor 11' has two notches 38, 39 
parallel to each other and arranged to intersect the passing hole of the 
dowel on both sides of its symmetry axis. Two flexible laminations 40, 41 
are provided with free ends bent back and are inserted in the two passages 
38, 39 so as to pass with their central part in the dowel hole clear 
space. 
Upon insertion of the dowel 42 the two laminations engage elastically in 
the notches of the latter and prevent its withdrawal. Bending back of the 
ends of the laminations has the result that on their exterior side remains 
a free opening which allows elastic bending thereof in opposite directions 
as shown in FIG. 11 upon rotation of the dowel so as to permits its 
withdrawal merely by 90.degree. rotation. With this embodiment the dowel 
anchor need not be of elastic material. Clearly the lamination means 40, 
41 need not consist of a flat lamination but can be in the form of a piano 
wire with round section. 
As another embodiment variation in FIG. 9 the dowel 42 is shown with the 
stem longer than the seat in the dowel anchor to permit e.g. fastening of 
elements which are thick or furnish a side surface like a cam for known 
closing mechanisms. 
FIG. 12 shows a further dowel anchor joint element made in accordance with 
the present invention and indicated generically by reference number 110, 
and which comprises a dowel anchor body 111 provided in relatively 
yielding material, e.g. plastic. The dowel anchor 111 has a substantially 
cylindrical shape with circumferential ribbings 112 of generally 
triangular cross section and tapered in the direction of insertion of the 
dowel anchor in a hole or reception seat. The dowel anchor 111 has an 
axial hole for reception of a dowel 114 with widened head. The bottom of 
the hole 113 terminates in a widened seat 115 in which is inserted an 
elastic washer 116. As may be seen also in FIG. 13 the washer 116 is 
shaped with a plurality of teeth or tabs 117 directed radially toward the 
axis of the hole 113 and appropriately inclined in the direction of 
insertion of the dowel 114 in the hole 113. The teeth delimit with their 
ends a passage with dimensions slightly less than the diameter of the 
dowel. 
As shown in FIG. 14, when in use the dowel anchor 111 is inserted by 
pressure inside a hole made in the fastening surface 120, e.g. a wall or a 
door of a furniture item. The stem of the dowel 114 is passed through a 
hole provided for that purpose in the hardware element or part 122 which 
it is wished to constrain to the surface 120 and then engaged by force in 
the hole 113. When inserting the dowel in the hole 113 the slight forcing 
of the dowel on the edges of the washer teeth 117 cause the teeth to bend 
slightly without exerting excessive resistance to complete introduction of 
the dowel. Axial withdrawal of the dowel is prevented by the digging 
effect resulting from the angle formed by the teeth with the axis of the 
dowel. 
It is clear that such a dowel anchor fastener does not require particularly 
close axial positioning tolerances. Furthermore its assembly is very fast 
and requires no assembly tools, 
If it is desired to provided a disassemblable system in order to permit 
withdrawal of the dowel it is possible, for example as illustrated by the 
threads shown on the shanks of the dowels 114 in FIGS. 12 and 14, to 
provide the dowel with a light helical cut or threading along its 
cylindrical wall. In this manner the dowel locks in the dowel anchor as 
described above but can be easily removed by rotating it with a 
screwdriver. For this purpose the dowel head is cut. Optionally extraction 
can be aided by a slight axial traction during rotation. 
As an alternative to or conjointly with the helical cut the teeth 117 can 
be provided inclined so that their ends form a screw in such a manner that 
the rotary movement of the dowel pushes it in an axial direction. In 
addition to disassembly the capability of axial movement of the dowel as a 
result of its rotation also permits increase of traction of the joint by 
rotating the dowel in a direction opposite that of disassembly to increase 
its penetration in the dowel anchor, 
As may be seen in FIGS. 12 and 14, to prevent the teeth of the washer from 
overturning under the axial traction effect exerted by the dowel the 
bottom of the cavity 115 can be advantageously provided an tapered form. 
This prevents the teeth from straightening beyond the taper angle of the 
bottom on which the washer rests. 
In addition the washer, e.g. pressed from sheet metal, can advantageously 
comprise peripheral projections or tabs 118 which engage in corresponding 
seats 119 in the dowel anchor to prevent rotation thereof with the 
rotating dowel. 
To give good support to the threaded dowel teeth it was found advantageous 
to provide the threading with a number of threads equal to the number of 
teeth. 
At this point it is clear that the purposes of the present invention have 
been achieved by supplying quick joints of great economy and safe holding. 
Naturally the above description of an embodiment applying the innovative 
principles of the present invention is given merely by way of example and 
therefore is not to be taken as a limitation of the patent right claimed 
here. For example, the proportions of the various parts can vary depending 
on the specific requirements of use. In addition, if disassembly 
capability is not required in embodiment show in FIG. 12, helical 
machining of the teeth can be avoided. The washer can also be incorporated 
in the dowel anchor during a pressing phase of said dowel anchor.