U.S. patent number 3,828,421 [Application Number 05/303,065] was granted by the patent office on 1974-08-13 for method of clamping and riveting parts.
This patent grant is currently assigned to Polaroid Corporation. Invention is credited to Irving Erlichman.
United States Patent |
3,828,421 |
Erlichman |
August 13, 1974 |
METHOD OF CLAMPING AND RIVETING PARTS
Abstract
Wire slugs for use as rivets are passed from a slug-forming
station to a partial riveting station where a ram forces a slug
through a restricted orifice in a spring-loaded guide and clamp
member so that the guide and clamp member is pressed against the
parts to be riveted as the slug is forced through the orifice into
aligned holes in the parts. The parts are positioned upon an anvil
which may be a fixture mounted on a turntable moveable from station
to station, and the anvil has recesses into which the lower portion
of the slug is forced to form a lower cap. The hole in the bottom
part is preferably slightly smaller than the hole through the top
part so that the slug material will flow outwardly filling the top
hole. locking the parts in place and rendering hole alignment
noncritical. Upon retraction of the ram, the spring-loaded guide
and clamp member is elevated above the partially formed rivet and
the two joined parts. The subassembly and anvil may then be moved
to a rivet completion station where formation of a top rivet cap
may be completed.
Inventors: |
Erlichman; Irving (Wayland,
MA) |
Assignee: |
Polaroid Corporation
(Cambridge, MA)
|
Family
ID: |
23170387 |
Appl.
No.: |
05/303,065 |
Filed: |
November 2, 1972 |
Current U.S.
Class: |
29/524.1; 29/34B;
29/526.2; 403/408.1; 29/525.06 |
Current CPC
Class: |
B21J
15/02 (20130101); B21J 15/32 (20130101); Y10T
403/75 (20150115); Y10T 29/49943 (20150115); Y10T
29/5118 (20150115); Y10T 29/49972 (20150115); Y10T
29/49956 (20150115) |
Current International
Class: |
B21J
15/02 (20060101); B21J 15/00 (20060101); B21d
039/00 (); B23p 011/02 () |
Field of
Search: |
;29/522,34B,243.53,526
;113/116FF ;52/758D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Moon; Charlie T.
Attorney, Agent or Firm: Rothstein; Sheldon W. Cooke; Susan
M.
Claims
What is claimed is:
1. A method for riveting parts together comprising placing
superimposed parts onto an anvil, said parts having rivet-receptive
holes in substantial alignment, said anvil portion in alignment
with said holes being capable of forming a rivet head, forcing a
slug through a restricted orifice of smaller diameter than that of
the slug into the substantially aligned holes in said parts from
the side opposite the anvil, and utilizing the pressure generated
in forcing the slug through said orifice to clamp said parts to the
anvil, and then forcing said slug into engagement with said anvil
portion and deforming both ends of said slug to thereby rivet the
parts together.
2. A method according to claim 1 which includes the step of forming
cap means on the forward edge of said slug.
3. A method according to claim 1 further comprising providing the
hole in the part most distal from said anvil with a larger diameter
than the holes in the other parts joined and deforming a portion of
said slug outwardly into the larger hole to lock the parts to each
other.
4. A method according to claim 1 further comprising removing the
pressure clamping the parts to each other, and thereafter
completing the formation of the slug into a rivet including forming
a cap portion on the side of the rivet opposed to said anvil.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a riveting method and apparatus,
and more particularly to an automatic riveting technique which may
be employed in an assembly line operation to rivet parts to one
another.
Although the riveting art is old and well developed, there are
still a number of problems associated with this technique,
particularly in automatic riveting systems. For example, a
frequently occurring problem is that the rivet in the final product
does not completely fill the holes in the parts through which it
extends and thus the rivet is loose allowing for slight movement of
the parts and reducing the strength of the united parts. In the
case of automatic riveting systems, there are problems concerned
with properly feeding the slugs from which the rivets are formed
and with maintaining alignment of the parts to be riveted during
the rivet-forming step. A common cause of work stoppage is loose
rivets jammed into guide and feed systems.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide an improved
automatic riveting system.
Another object of the invention is to provide novel riveting
apparatus which eliminates loose rivets and provides a stronger
joint between the riveted parts.
Still another object of the invention is to provide a riveting
apparatus in which pressure generated by extruding a slug through
an orifice in the course of positioning the rivet-forming slug in
aligned holes within the parts to be riveted is also utilized to
clamp the parts in position.
A further object of the invention is to provide an improved, novel
automatic riveting process in an assembly line operation.
Briefly, the present invention utilizes apparatus for feeding a
metal or appropriate synthetic plastic rod to a reciprocating shear
punch which shears off a slug from the rod and positions the slug
over a spring loaded transfer guide and clamp member. A ram then
pushes the slug out of the shear punch and extrudes the slug
through a restricted sizing orifice in the guide and clamp member
into aligned holes on superimposed parts to be riveted which are
positioned upon an anvil. The extrusion pressure forces the
transfer guide and clamp member downwardly against a biasing force
so that the parts to be riveted are clamped in position between the
guide and clamp member and the anvil. At this time, a cap is
partially formed on the lower end of the rivet. The hole in the
upper part to be riveted is preferably slightly larger than the
hole in the lower part so that the upper periphery of the rivet can
expand into the larger hole locking the parts to each other even
though there is not an upper cap on the rivet at this time. Using a
larger hole in the upper part than the lower part eliminates the
requirement of positioning the parts to close tolerances.
Upon retraction of the ram, the spring-loaded transfer guide and
clamp member is elevated out of contact with the united parts. To
facilitate this, the lower portion of the opening through the guide
and clamp member flares outwardly and downwardly to prevent binding
of the expanded rivet to the sides of the member opening. This
should be configured to a nonlocking angle like a lathe collet. The
anvil, which may be in the form of a fixture on an indexed
turntable, may now be moved to a rivet completion station, if
desired, where a second ram descends onto the partially formed
rivet to complete the formation of the rivet insuring that the
holes in the parts are completely filled and that caps are formed
on each end of the rivet. After retraction of the second ram, the
anvil is moved to a further station at which the finished article
is discharged and the anvil is returned to a parts feeding station
for the commencement of another cycle of operation.
The above and other objects, features and advantages of the
invention will become more apparent as this description
proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a somewhat diagrammatic view, partially in section, of a
presently preferred embodiment of the invention;
FIG. 2 is a view of a portion of the apparatus of FIG. 1 showing
the spring-loaded transfer guide and clamp member in its lower,
part-clamping position;
FIG. 3 is a view taken primarily in vertical section showing a
partially-formed rivet at the rivet completion station; and
FIG. 4 is a view similar to FIG. 3 but showing the arrangement of
the apparatus at the completion of the rivet-forming operation.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawing and more particularly to FIG. 1, a
metal rod 10, which is the stock material for the production of the
rivets, is progressively fed downwardly through a stationary,
hollow cylindrical rod guide 12 by a chuck feed mechanism or the
like (not shown) into an opening 14 in a reciprocating shear punch
16 when the punch is in a retracted position in which the opening
14 is beneath the opening in the rod guide 12. Movement of punch 16
towards the position shown in FIG. 1 causes a slug 18 to be sheared
off of the rod 10. At the conclusion of the outward stroke or
movement of punch 16, the slug 18 is positioned as shown in FIG. 1
directly beneath a ram 20 which has an outer diameter slightly
smaller than the inner diameter of the opening 14 in the punch 16.
Punch 16 reciprocates on top of a support 22. A slug transfer guide
and clamp member 24 is disposed beneath punch 16 in alignment with
ram 20 and is connected to support 22 so as to enable vertical
movement of the guide and clamp member relative to support 22. A
spring 26 normally maintains the guide and clamp member biased into
the position shown in FIG. 1 in which this member abuts the lower
surface of support 22.
As shown in FIGS. 1 and 2, the guide and clamp member 24 has a
passageway through which the slug 18 is forced. The passageway has
an outwardly flaring inlet or mouth 28 which has a diameter greater
than that of the slug and which includes a restricted sizing
orifice 30 which has a diameter slightly smaller than that of slug
18, and an outwardly flaring discharge section 32.
A pair of upper and lower parts 34 and 36 to be riveted to each
other are positioned upon an anvil 38 when the anvil is at a part
feed station (not shown), and then the anvil is moved to the
position shown in FIGS. 1 and 2. By way of example, the anvil 38
may be part of an indexed turntable having a plurality of anvils
disposed about its periphery. The upper and lower parts 34 and 36
have aligned holes 40 and 42 respectively which, as seen in FIGS. 1
and 2, are not only aligned with each other but with the passageway
through the transfer guide and clamp member 24. The diameter of
hole 40 in the upper part is preferable greater than the diameter
of the hole 42 in the lower part. As has been stated, this
differential sizing allows parts placement without adhering to
close tolerances.
Upon the downstroke of ram 20, the slug 18 is pushed downwardly out
of the hole 14 in punch 16 and through the restricted sizing
orifice 30. Since orifice 30 is smaller than the initial diameter
of slug 18, it is necessary to extrude the slug through orifice 30.
The resulting generated pressure acting upon the wall of the
passageway through guide and clamp member 24 just above orifice 30
forces the guide and clamp member downwardly against the bias of
spring 26 into the position shown in FIG. 2. In this position, the
lower surface 44 of the guide and clamp member 24 is pressed
against the upper surface of part 34 thereby clamping parts 34 and
36 between it and the upper surface of anvil 38. With the parts 34
and 36 now firmly held in position by the pressure generated in
extruding the slug through orifice 30, further downward movement of
ram 20 causes the lower end of the slug 18 to assume the
configuration illustrated in FIG. 2 in which the lower end of the
slug has partially filled recess 46 in the anvil 38. This recess
has the configuration of the cap desired at the bottom of the
rivet. At the same time, the sides of slug 18 expand outwardly
filling the hole 42 in the lower part 36 and at least substantially
filling the larger hole 40 in the upper part 34. The expanded
portion of the slug in hole 40 overlies the upper, inwardly
extending peripheral edge of the lower part 36 in the vicinity of
hole 32 so that parts 34 and 36 are rigidly connected to each other
even though the rivet has not been completely formed at this point.
Added pressure by ram 20 forces the slug to fill cavity 46 and
spread filling the shaped wall of guide 32. This forms the
semi-finished assembly.
As the next step in the sequence, ram 20 is retracted to the
position shown in FIG. 1. Spring 26 now elevates the guide and
clamp member 24 back to the FIG. 1 position out of contact with the
partially formed rivet and the parts 34 and 36. In view of the
outward flare of the discharge section 32 which may flare outwardly
at an angle of about 15.degree. from the vertical, the partially
formed rivet does not bind to the guide and clamp member and
prevent its retraction. The turntable-mounted anvil 38 is
automatically advanced to the rivet completion station.
As shown in FIG. 3, the partially formed rivet now has the
configuration designated by reference numeral 18'. At the rivet
completion station the partially formed rivet is indexed beneath a
ram 48 which is positioned within a support 50 to enable vertical
reciprocating movement of the ram. The working face 52 of the ram
is contoured to the configuration of the upper cap desired upon the
rivet. Ram 48 is now driven down onto the partially formed rivet
18' to further deform this member into the configuration of the
completed rivet shown by reference numeral 18" in FIG. 4. As seen
in this figure, at the completion of the final riveting step, caps
are formed on both ends of the rivet and the rivet has expanded to
completely fill the holes in the parts 34 and 36.
Upon retraction of ram 48, the turntable is advanced to a discharge
station at which the riveted parts are removed and deposited, for
example, upon a conveyor for transfer to a further assembly system.
The anvil 38 is now returned to the part feed station to commence
another cycle of operation.
As will be appreciated by those skilled in the art, suitable
control means for controlling the above disclosed sequence of
operations including prearranging a suitable timing sequence and
signals to indicate when one operation has been completed and when
to commence the next step are now well known in the art and thus
specific disclosure of such devices in the present specification is
unnecessary.
While a presently preferred embodiment of the invention has been
shown and described with particularity, it will be appreciated that
various changes and modifications may readily suggest themselves to
those of ordinary skill in the art upon being apprised of the
present invention. It is intended to encompass all such changes and
modifications as fall within the scope and spirit of the appended
claims.
* * * * *