Magnetic stem and vertically fixed pocket device for a stationary riveting machine

A magnetic riveting stem and a novel vertically fixed pocket mechanism is provided for a stationary riveting machine which permits such machines to be used for riveting applications which were impossible or impractical with prior art riveting stem and pocket mechanisms. The vertically fixed pocket receives ferrous rivets from a rivet feed mechanism and aligns them in a head-up orientation to be picked up by the stem for setting through registered holes in the work. A stationary riveting machine equipped in accordance with the invention is capable of setting a ferrous rivet in practically any location on a work piece where the head of the rivet can pass. This offers an advantage over traditionally equipped stationary riveting machines which require vertically displaceable pockets for guiding a rivet to the pilot pin of a rivet anvil.

The present invention relates to stationary riveting machines, and in 
particular, to improvements in a stationary riveting machine whereby a 
magnetic riveting stem and a vertically fixed pocket mechanism for setting 
ferrous rivets is provided. 
BACKGROUND OF THE INVENTION/PRIOR ART 
Stationary riveting machines are well known and widely manufactured. 
Traditionally, stationary riveting machines include a work table supported 
on a frame, a riveting plunger or ram supported above the work table, and 
a riveting stem for setting rivets which is attached to the riveting 
plunger. The work table is provided with an anvil for upsetting or 
deforming a rivet after it passes through the registered holes of a work 
piece. The anvil includes a spring biased pilot pin which is used to 
register the holes in the work and to guide a rivet through the registered 
holes. The traditional riveting machine also includes a mechanism commonly 
known as a "pocket" for transferring a rivet from a rivet feed mechanism 
to the anvil pilot pin. 
A riveting pocket includes a pair of vertically displacable opposing jaws 
which receive rivets in succession from a rivet feed mechanism. The 
opposing jaws of a riveting pocket are provided with a vertical bore along 
their common faces which is sized to accommodate the head of a rivet in an 
upper region of the bore and the shank of the rivet in a lower region of 
the bore. Each side of a riveting pocket is attached to a spring-steel 
pocket arm which permits the opposing jaws of the pocket to be forced 
apart laterally. The pocket arms are, in turn, connected to a linkage 
which controls the vertical movement of the pocket. 
During each riveting cycle the pocket moves vertically from a rivet 
receiving position above the work piece to a rivet release position 
wherein the hollow lower end of the rivet shank has engaged the tip of the 
pilot pin. Most stationary riveting machines control the vertical movement 
of the pocket with a spring or cam biased linkage that is attached to the 
top of the pocket arms. The linkage is adjusted to stop the descent of the 
pocket when the transferring a rivet from a rivet feed mechanism to the 
anvil pilot pin. 
A riveting pocket includes a pair of vertically displaceable opposing jaws 
which receive rivets in succession from a rivet feed mechanism. The 
opposing jaws of a riveting pocket are provided with a vertical bore along 
their common faces which is sized to accomodate the head of a rivet in an 
upper region of the bore and the shank of the rivet in a lower region of 
the bore. Each side of a riveting pocket is attached to a spring-steel 
pocket arm which permits the opposing jaws of the pocket to be forced 
apart laterally. The pocket arms are, in turn, connected to a linkage 
which controls the vertical movement of the pocket. 
During each riveting cycle the pocket moves vertically from a rivet 
receiving position above the work piece to a rivet release position 
wherein the hollow lower end of the rivet shank has engaged the tip of the 
pilot pin. Most stationary riveting machines control the vertical movement 
of the pocket with a spring or cam biased linkage that is attached to the 
top of the pocket arms. The linkage is adjusted to stop the descent of the 
pocket when the rivet shank engages the top of the pilot pin. When the 
pocket is stopped in its downward descent, the opposing jaws of the pocket 
are forced apart by the descending force of the stem and the rivet follows 
the pilot pin down through the registered holes of the work pieces and is 
upset against the anvil on the back side of the work. 
The disadvantage of the known stationary riveting machines is the fact that 
the riveting pocket prevents the setting of rivets in certain areas of a 
work piece. For instance, using a traditionally equipped riveting machine, 
one cannot readily set a rivet adjacent a 90.degree. angle, in the bottom 
of a narrow cylinder, or in any other location where a rivet is desirably 
set in a portion of the work adjacent some obstruction or protrusion. This 
problem often requires the use of more expensive and less desirable "pop" 
rivets or some alternate fastener where an upset rivet cannot be set. In 
certain applications, the size of a pocket is sometimes reduced to improve 
the versatility of the machine. Elongated pilot pins which project far 
enough above the work to guide a rivet past a projecting surface of the 
work have also been used for setting rivets in certain applications. 
Neither of these adaptions have proven practical for all applications. 
Regardless of how thinly the walls of a pocket are made, the pocket still 
requires considerable operating space, rendering it unsuitable for certain 
riveting applications. Although an elongated pilot pin may be useful in 
certain situations where only a few rivets must be set, it is an 
unsatisfactory method for setting a large number of rivets. There are 
several disadvantages to working with an elongated pilot pin. Firstly, the 
pin requires a very long and resilient spring which tends to fatique and 
wear quickly. Secondly, the extra long projection of the pilot pin 
provides less clearance between the bottom of a pocket and the top of the 
pin, which may interfere with the movement of work pieces over the pilot 
pin. In addition, attempts to match a hole with a very long pilot pin may 
result in damaging the pilot pin by bending or breaking it and thus 
rendering it unsuitable for further use. 
It is an object of the present invention to provide a riveting stem and a 
pocket for a stationary riveting machine which is reliably capable of 
setting ferrous rivets in practically any area of a work piece, including 
areas adjacent projecting surfaces, inside corners, and within narrow 
recesses. 
It is a further object of the invention to provide a riveting stem and 
pocket for a stationary riveting machine which are simple to manufacture, 
operate and maintain. 
SUMMARY OF THE INVENTION 
The present invention provides a novel magnetic stem for stationary 
riveting machines. A magnetic stem permits the use of a vertically fixed 
pocket, eliminating the need for the traditional linkage which controls 
the vertical movement of a riveting pocket. 
In accordance with the preferred embodiment of the invention, a stationary 
riveting machine is provided with a magnetic stem and a novel riveting 
pocket which receives ferrous rivets from a rivet feed mechanism and 
releases them to the stem as the stem descends in its rivet setting 
stroke. Because the pocket of the present invention does not descend with 
the stem to guide the rivet onto the pilot pin of the anvil, rivets may be 
driven in close proximity to vertical surfaces on a work piece. A 
stationary riveting machine in accordance with the invention is capable of 
setting a ferrous rivet in almost any location that permits the passage of 
the head of a rivet. This adds a great deal of versatility to the 
capability of the machine and eliminates the traditional problems 
associated with setting rivets in inaccessible areas of a work piece. 
For the purposes of this document, "ferrous rivets", hereinafter generally 
referred to simply as "rivets" means any rivet which contains sufficient 
iron to render it magnetic. 
The present invention may be described in more general terms as follows. 
In a stationary riveting machine, apparatus for setting ferrous rivets 
having a head portion, a shank portion of smaller cross-section extending 
therefrom and an axis extending longitudinally of said shank, said 
apparatus comprising: 
a riveting stem connectable with the plunger of said riveting machine, said 
stem having a shank and a riveting tip, at least a portion of the tip 
region of said stem being magnetic so as to support one said rivet in a 
head-up contact therewith; and 
means for aligning a rivet in the path of said stem and releasing said 
rivet to said stem before said rivet contacts the pilot pin of the anvil 
of said riveting machine.

DETAILED DESCRIPTION OF THE INVENTION 
As illustrated in FIG. 1, a traditional stationary riveting machine 
generally includes a riveting stem 10 which drives a rivet through the 
registered holes of a work piece. The rivet is upset on the back of the 
workpiece when it strikes an anvil 12, axially aligned below the end of 
the stem 10. The stem is driven down by a riveting plunger 14 which is in 
turn connected to a power source for providing the force required for 
setting rivets. Rivets 16 are delivered one at a time to a riveting pocket 
18. In FIG. 1, only one side of a riveting pocket is illustrated, the 
opposite side being removed for clarity. A riveting pocket 18 generally 
includes a hollow cylinder which is split into two jaws along a 
longitudinal midline. The cylinder has a first bore 20 which accommodates 
the head of a rivet and a second bore 22 which accommodates the stem of 
the rivet (FIG. 2b). The front face of the cylinder is provided with a 
vertical slot 24 (FIG. 2a) which permits the head and shank of a rivet to 
slide laterally into the pocket. Rivets are delivered to the pocket by a 
rivet track 26. This track is fed from a source of rivets and supplies one 
rivet to the riveting pocket during each riveting cycle. Rivet feed tracks 
are well known in the art. The pocket 18 is traditionally supported by a 
pair spring-steel pocket arms 28. The pocket arms are in turn connected to 
a spring biased or cam actuated linkage which controls the vertical 
movement of the pocket relative to the riveting stem and plunger. 
In FIG. 1, the stem 10 has just entered the pocket 18 during its descent 
for setting the rivet 16. The pocket 18 must descend with the stroke of 
stem 10 until the hollow tip of rivet 16 engages the pointed tip of the 
pilot pin 30 which projects up through the registered holes in work pieces 
32 and 34. The pilot pin 30 is spring biased and projects through a 
concentric bore in the end of anvil 12. Pilot pin 30 serves the dual 
purpose of assisting in registering the holes in work piece 32 and 34 as 
well as guiding the end of the shank of rivet 16 through the registered 
holes in the work pieces. The spring biased arms (not illustrated) which 
control the vertical movement of pocket 18 are adjusted to stop the pocket 
18 when the end of rivet 16 is in firm contact with the top of pilot pin 
30. When the pocket 18 is stopped in its downward travel, the pressure of 
stem 10 forces the opposing jaws of pocket 18 to separate laterally, 
permitting the stem to descend with the rivet, forcing the spring loaded 
pilot pin 30 into its socket and upsetting the shank of rivet 16 against 
anvil 12 on the back side of the work piece 34. 
As is readily apparent from the above, the pocket 18 must descend within 
close proximity of the work piece before releasing a rivet. Since the 
pockets are relatively bulky in size, traditionally equipped stationary 
riveting machines are not capable of setting rivets in areas closely 
adjacent to vertical surfaces on a work piece. 
FIG. 3 illustrates a novel rivet setting apparatus in accordance with the 
invention. The apparatus includes a magnetic stem 36, a novel pocket 38, 
shown partially cut away for clarity, and pocket support arms 40. It 
should be noted that pocket support arms 40 are pivotally connected to the 
head of the riveting machine by bolts 42. The pocket may alternatively be 
attached to another convenient location on the machine. Pocket support 
arms 40 are biased toward each other by a coil spring 44 attached across 
the opposing arms. Alternatively, the pocket support arms 40 may be biased 
toward each other by leaf springs which exert inward pressure on the outer 
surface of each arm. Stem 36 is preferably constructed of stainless steel 
and includes a magnetic insert 46 so that, as the stem descends in its 
rivet setting stroke, the rivet 16 adheres to the end of the stem 36 and 
is centered on the stem as it passes through the pocket bore which is 
approximately the same diameter as the rivet head and the end of the stem. 
Because the pocket 38 is vertically fixed, stem 36 forces the opposing 
jaws of pocket 38 apart laterally and descends with rivet 16 to pilot pin 
30. As the the pocket 38 does not have to control rivet 16 to the point 
that it contacts pilot pin 30, a rivet can be set in locations which were 
impossible or impractical to reach with traditional rivet setting 
apparatus. As shown in FIG. 3, a rivet may be set in the bottom of a 
channel 48 which is being riveted to a flat bar 50. The same operation 
with the apparatus shown in FIG. 1 would be impossible without the use of 
an elongated pilot pin. 
FIG. 4b is a detailed illustration of the pocket 38 shown in FIG. 3. The 
pocket illustrated is constructed from a substantially square block, 
however, the exterior shape of the pocket is of no consequence. The pocket 
is preferably constructed from non-magnetic material such as stainless 
steel, nylon, bronze, a cast aluminum alloy or some other durable 
non-magnetic material. It is preferred that pockets in accordance with the 
invention be constructed from non-magnetic material so that no magnetism 
is passed from the stem via the pocket to the rivet feed mechanism. 
Magnetism passed to a rivet feed mechanism inevitably impairs its proper 
functioning by causing rivets to stick to the end of the feed track and is 
therefore undesirable. If a pocket constructed from non-magnetic material 
is used, this problem is avoided. Stainless steel is the preferred 
material because it is more durable and easily worked than most other 
materials, though other non-magnetic materials are equally satisfactory in 
terms of function. A pocket 38 in accordance with a preferred embodiment 
of the invention may be constructed as follows. 
(a) a pair of appropriately sized stock pieces having common plane faces 
are clamped together; 
(b) a vertical bore 54 equal to the head diameter of the rivet is drilled 
along the junction line of the two stock pieces; 
(c) 0.010 inches is removed from the drilled face of each block; 
(d) the blocks are reclamped together and the top of the block is redrilled 
to form the bore 52 having the diameter of the rivet head plus 0.015 
inches; 
(e) a vertical notch is ground to communicate from the outside of the 
pocket to the vertical bore 54, forming slot 56 which provides a 
passageway for the stem and head of rivets fed to the pocket; 
Pockets 38 are assembled to pocket arms 40 and the pocket is ready for 
assembly to a riveting machine. 
A pocket constructed to the above specifications serves for all rivets of a 
given head diameter, regardless of the rivet shank diameter or the shank 
length. Conversely, one prior art pocket must be kept in stock for each 
rivet head and shank diameter combination to be used in riveting 
applications. Additionally, each prior art pocket can accommodate only a 
narrow range of rivet shank lengths, further adding to the number of prior 
art pockets which must be kept in stock. 
It will be appreciated by those skilled in the art that many alternative 
pocket constructions are readily adaptable for use with a riveting stem in 
accordance with the invention. 
FIG. 5 illustrates a riveting stem 36 in accordance with a preferred 
embodiment of the invention. The stem may be identical in shape to a 
traditional riveting stem. The preferable construction for a magnetic stem 
is one turned from a non-magnetic material such as stainless steel. An 
appropriately sized axial bore is drilled in the tip of the stem. The 
depth of the bore is not critical but 1.5 cm to 2.5 cm has proven 
satisfactory. A magnetic rod cut to the proper length is driven into the 
axial bore in the stem so that it is flush with the end of the stem. A 
magnetic alloy, known as Alnico, commonly available from steel suppliers, 
has proven acceptable for this application. A short magnetic cylinder can 
also be soldered to the end of a stem using a silver solder or an 
equivalent. This has disadvantages however in that the heat required to 
solder the magnet to a stem can cause the magnet, stem, or both to become 
tempered to a brittle consistency which shortens the life of the stem in 
its riveting application. Additionally, as shown in FIGS. 6a and 6b, the 
magnetic field of a short cylinder is more concentrated towards the edge 
of the cylinder as opposed to the magnetic field of a long thin rod which 
is more concentrated near the centre of the end of the rod. A rivet head 
attracted to a short cylindrical magnet is, therefore, more inclined to 
tip and adhere to one side of the magnet than a rivet attracted by a thin 
rod axially mounted in a non-magnetic stem. Although the problem of rivet 
tipping can be controlled with the use of a properly designed pocket, it 
is preferably avoided with a stem constructed in accordance with the stem 
illustrated in FIG. 5. 
Changes and modifications in the specifically described embodiments can be 
carried out without departing from the scope of the invention which is 
intended to be limited only by the scope of the appended claims.