U.S. patent number 3,789,495 [Application Number 05/218,821] was granted by the patent office on 1974-02-05 for method for manufacturing box spring.
This patent grant is currently assigned to Simmons Company. Invention is credited to Walter Stumpf.
United States Patent |
3,789,495 |
Stumpf |
February 5, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
METHOD FOR MANUFACTURING BOX SPRING
Abstract
A method and apparatus for assembling box spring "constructions"
by stapling rows of springs to a base frame. The method utilizes a
wire spring coil in which the wire at one end of the coil is bent
to cross the bottom convolution so that stapling gun inserted
axially into the spring from the other end will secure the spring
to the frame with one staple. The staple is driven with enough
force to impress the cross-wire into the surface of the frame. The
apparatus handles the springs and frames upside down, the guns
being lowered for loading with springs, and raised for firing. The
gun muzzles are adapted to receive an inverted spring and to
position it rotatively so that the staple when driven will encircle
the cross-wire from which the spring is suspended on the gun. After
each firing, the frame indexes for another row, and is followed at
a controlled interval by a second frame brought into the mechanism
automatically from a magazine.
Inventors: |
Stumpf; Walter (Munster,
IN) |
Assignee: |
Simmons Company (New York,
NY)
|
Family
ID: |
22816648 |
Appl.
No.: |
05/218,821 |
Filed: |
January 18, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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829533 |
Jun 2, 1969 |
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Current U.S.
Class: |
29/429; 227/99;
227/147 |
Current CPC
Class: |
B21F
33/04 (20130101); B27F 7/17 (20130101); Y10T
29/49828 (20150115) |
Current International
Class: |
B21F
33/04 (20060101); B21F 33/00 (20060101); B27F
7/17 (20060101); B27F 7/00 (20060101); B23p
021/00 () |
Field of
Search: |
;29/429,225 ;5/248,263
;227/39,40,120,147,99 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Herbst; Richard J.
Assistant Examiner: Crane; D. C.
Attorney, Agent or Firm: Fitch, Even, Tabin &
Luedeka
Parent Case Text
This is a division of my co-pending application, Ser. No. 829,533,
filed June 2, 1969 and now abandoned.
Claims
What is claimed is:
1. The method of assembling a wire spring coil to a base frame in
the manufacture of box springs, or the like, comprising
forming a spring coil to have a wire portion extending into the
space defined by an end convolution of the coil,
presenting said end convolution of the coil to the surface of the
base frame to which said coil is to be assembled, and
driving a staple around said wire portion and into said base frame
by means of stapling gun inserted into the coil axially thereof,
thereby to secure the spring coil to the frame.
2. The method of assembling wire springs with a base frame in the
manufacture of box springs or the like, comprising
supporting the base frame in an inverted position for travel by
edgewise movement to an assembly station,
bucking the base frame from above and pressing a spring against the
underside of said base frame while driving a fastener around the
wire of the spring and into the base frame from below,
indexing the frame by said edgewise movement to present successive
portions of said frame at said station to receive a spring, and
repeating said bucking, pressing and indexing steps until the
desired number of springs has been united with the base frame.
3. The method of assembling wire springs with a base frame in the
manufacture of box springs or the like, comprising
supporting the base frame in an inverted position for travel by
edgewise movement to an assembly station having a row of upwardly
directed stapling guns,
emplacing a row of wire springs upon said row of guns to position a
portion of the spring wire for encircling interception by the
staple of each associated gun,
bringing said row of guns with springs emplaced thereon into
contact with the underside of said base frame,
bucking the base frame from above while stapling the springs to the
frame,
indexing the frame by said edgewise movement to present successive
portions of said frame at said station to receive another row of
springs, and
repeating said emplacing, bringing, bucking and indexing steps
until the desired number of springs has been united with the base
frame.
4. The method of claim 3 wherein the springs employed are coil
springs having a wire portion extending as a choral element into an
end convolution of the coil, and the coil is placed over the end of
its associated gun so that the gun extends into the interior of the
coil with the end of the gun engaging the chordal element and
oriented rotatively with respect thereto so that the chordal
element is the wire portion straddled.
5. The method of claim 1 in which the base frame is wood and in
which the staple is driven with force sufficient to impress the
said wire portion into the surface of the wood.
6. The method of claim 1 wherein said base frame is supported in an
inverted position and said end convolution of the coil is presented
to the undersurface of the inverted base frame.
7. The method of claim 6 wherein said end convolution of the coil
is carried upward to the undersurface of the base frame by said
stapling gun.
8. The method of claim 2 wherein said wire spring has a wire
portion extending as a chordal element into and end convolution
thereof and wherein said fastener is driven around said chordal
element.
9. The method of claim 8 wherein said base frame is wood and
wherein said bucking and said driving impresses said chordal
element into the undersurface of the wood frame.
10. The method of claim 4 wherein the base frame is wood and
wherein said bucking and said stapling impresses said chordal
element into the undersurface of said wood frame.
Description
This invention relates to the manufacture of box springs, by which
term I mean to include not only box springs as such, i.e.,
upholstered spring constructions mounted upon flat wooden frames
and usually employed upon a bedstead or bedframe as a foundation
for a mattress, but also similar such upholstered constructions
employed as bases of studio couches, upholstered sofas, upholstered
chairs, and the like.
The invention relates particularly (1) to a method of assembling
springs into a "construction," i.e., the arrangement of individual
coil springs into a series of rows in regular pattern by virtue of
the attachment of such spring coils individually to a base frame of
wood or the like by means of stapling; (2) to a special apparatus
for carrying out the method; and (3) to a particular form of spring
coil which is particularly adapted to the practice of the
method.
Since the days of the hand-tied box-spring construction, which once
constituted a majority of those made, particularly those of higher
quality, various attempts have been made to adapt the box spring
for machine assembly without a great deal of success. Until
recently, machine assembly of box springs has been limited to the
use of pre-assembled spring constructions of hour-glass coils such
as are used in mattresses, i.e., adjacent rows of springs united by
helical tie-wires, and the stapling of such assemblies or spring
constructions as a unit to a wooden slat frame. This technique is
essentially limited to the double-cone or hour-glass type of coil,
which has limitations both functional and economic when used as a
box spring, particularly for certain kinds of mattresses that best
serve their function when emplaced upon a relatively inflexible but
resiliently mounted platform.
Assembly of box spring constructions of the cone-coil type, which
is preferred for many sleeping and sitting cushion-bases, has been
performed essentially by hand, the spring coils being assembled by
hand methods into an assembly or "construction" of suitable size,
which is then secured to a wooden slat frame by stapling. The
process remains expensive because of the labor involved, and unless
considerable care be taken, the construction can be noisy if the
contacting metallic parts are not tightly interlocked.
While some attempts have heretofore been made to simplify the
assembly of box springs by stapling cone coils individually to the
wooden base frame, the methods employed have been cumbersome and
incapable of realizing the full potential of the stapling technique
because they have contemplated the use of the conventional coil,
and have accepted all of its limitations as premises.
It is the primary object of this invention, therefore, to improve
the mechanized manufacture of box springs, this object being
accomplished by a change in the character of the cone coil, the
provision of a stapling gun and technique adapted to handle such a
coil and to secure it to the slat frame with a single staple, and
the provision of the necessary apparatus to bring the component
parts together in a coordinated assembly, each of these aspects
being believed novel as defined by the claims herein.
SUMMARY STATEMENT
The method and apparatus of this invention utilizes the stapling
technique to fuller advantage by coupling it with a specially
designed cone coil so that each coil is securely anchored and
positioned by a single staple.
For the purpose of the technique and the apparatus hereinafter
described, this special form of coil may be differentiated from
others now in common use in that, at its small end, the final
convolution terminates in a chordal element which extends across
the end convolution approximately diametrically thereof. This
chordal element or cross bar at the small end of the coil becomes
not only the means for positioning and anchoring the coil on the
wooden slat frame, but is also the means by which the coil is
supported in the assembly apparatus, as well as the reference for
orienting the spring coils rotatively so as to position properly
the knots at their large ends for later assembly of the supporting
face of the box spring construction.
To summarize the assembly technique as briefly as possible, the
above-described coil is placed over the nose of a stapling gun, the
muzzle of which has been modified to receive the aforementioned
cross bar at the small end of the cone coil in such manner that the
staple when driven will encircle that bar approximately midway
thereof. In order to eliminate extraneous holding means for
maintaining this relationship of spring coil and stapling gun for
the stapling operation, the stapling is preferably performed with
the stapling gun pointed upwardly so that gravity holds the coil in
place. The obvious corollary is that the flat frame of the box
spring is inverted and overhead, the assembly being made in the
upside-down condition, the stapling gun with coil thereon being
moved vertically upwardly with respect to the slat frame to
position the coil thereon for stapling. The gun is then fired with
sufficient force not only to drive the staple securely into the
wood and into encircling engagement with the cross bar of the
spring, but also to impress or to indent the cross bar itself
firmly into the wood.
The apparatus for carrying out the method includes he vertically
positioned upwardly directed stapling guns in ganged or banked
array suitable for stapling at least one row of springs at a time
to the base frame. The guns are mounted on a movable carriage which
is moved by power from a lower loading position to an upper firing
position, and the stapling guns are suitably powered from a common
source and fired simultaneously by a common trigger control. The
inverted slat frame moves in suitable overhead ways, and is bucked
by a suitable backing arrangement at the stapling station, to which
and from which each cross slat of the base frame is indexed in turn
to receive a row of coils.
These successive operations are organized into a self-terminating
cycle by means of a suitable programming controller such that the
operator, after having charged each operative gun with a spring
coil, manually initiates the cycle which is thereafter
self-executing, and at the end of which the guns are returned to
the loading station, ready to be charged with another row of coils
for the commencement of yet another cycle.
While I have found it desirable from the standpoint of simple
explanation of the several steps of the method and features of the
apparatus to speak of hand loading the coils on the guns, I also
contemplate the charging of the guns by machine as well, using a
feeding apparatus of the kind disclosed in my U.S. Pat. No.
3,193,136 for presenting the inverted spring coils one at a time
from a nested stack of the same, to be picked up by the stapling
gun passing axially upwardly through the spring coil at such
feeding station.
THE DRAWINGS
The invention is described in detail in connection with the
accompanying drawings in which:
FIG. 1 is a fragmentary perspective view of a box spring
construction partially completed in accordance with the invention,
showing the spring assembly at one corner of the box spring
frame;
FIG. 2 is a side elevational view of the basic elements of the
assembly apparatus, illustrating the sequence of operations by
means of which the spring coil is carried by the stapling gun
upwardly to the slat frame and stapled thereto;
FIG. 3 is a side elevational view of the overall apparatus showing
a supply stack or magazine of the slat frames on the right,
uppermost one of which is on the ways and in the position at which
its leading cross slat awaits a row of springs at the stapling
station at the far left;
FIG. 4a is an elevational view of the stapling mechanism as the
operator sees it, i.e., from the right-hand side of the mechanism
as seen in FIG. 3, FIG. 4a showing the guns in retracted position
and charged with spring coils sufficient for a box spring of
less-than-full width, and showing the overhead ways moved inwardly
to accommodate the less-than-full-width slat frame;
FIG. 4b is a similar but fragmentary elevational view of the
mechanism shown in FIG. 4a, but showing the guns ready for firing,
i.e., with the spring coils elevated into contact with the cross
slat of the wood frame, and the overhead backing bars cammed into
solid "bucking" or shock-receiving contact with the upper side of
the slat;
FIG. 5 is a fragmentary perspective view of the stapling mechanism
as seen from the operator's station, showing in greater detail the
gun and its mounting, and the elevating and triggering
mechanisms;
FIG. 6a, FIG. 6b, and FIG. 6c are each enlarged, fragmentary
sectional elevational views of the frame feeding or indexing
mechanism, shown in the upper left-hand portion of FIG. 3, for
positioning each successive cross slat of the box frame at the
stapling station, FIG. 6a showing the end or leading cross slat
positioned to receive its coils, FIG. 6b showing the slat frame in
transit as the second cross slat of the frame is moved into the
stapling station, and FIG. 6c illustrating the second cross slat at
the stapling station, and illustrating as well how each succeeding
cross slat of the frame is thereafter so positioned;
FIG. 7 is an enlarged fragmentary end elevational view of the
indexing mechanism seen from the exiting end of the apparatus,
i.e., the left hand end as illustrated in FIG. 3;
FIG. 8a is an enlarged fragmentary elevational view of a portion of
the indexing mechanism, showing in particular the mechanism for
ejecting a completed assembly;
FIG. 8b is an enlarged fragmentary view of the indexing apparatus
showing the controller for the frame ejector of FIG. 8a; and
FIG. 9 is a diagram of the electrical circuit and controller by
means of which the aforementioned individual operations are
coordinated in an operating cycle.
THE SPRING COIL PROPER
The spring coil 20 is best seen in FIG. 1. It is a somewhat
modified cone coil in that its five and one-half convolutions do
not decrease in diameter linearly but rather abruptly from the
major diameter of the upper knotted convolution 22 to the main body
of the coil, which is of substantially smaller and so nearly
uniform diameter as to be almost cylindrical in appearance as
compared with the usual cone coil. To those familiar with the
spring art, it is apparent that this kind of coil exhibits a fairly
abrupt change in load carry from an initial softness to a
considerable stiffness as the first or closed convolution deflects
sufficiently to bring the succeeding convolution of smaller
diameter into contact with the load to be supported.
At its unknotted bottom end 24, the wire of the spring coil
terminates in a chordal element of cross bar 26 which is
approximately the length of the minor diameter of the coil and is
positioned approximately diametrically of the bottom convolution.
This chordal cross bar serves a number of purposes, not only in the
construction of the box spring itself but also in the handling and
the orientation of the coil by the assembly apparatus.
As will be seen in FIG. 1, the cross bar 26 at the bottom of the
coil is at or near the central axis of the coil, and also lies in
the plane that intercepts the knot 28 at the top convolution.
Inasmuch as the location of the knot at the top of the coil can be
important to the particular one of many available methods for
joining the individual coils together at their upper ends, the
desired final position of the knot 28 may easily be derived from
the bottom cross bar 26 as a reference, inasmuch as the muzzle of
the stapling gun, as will hereinafter be pointed out in detail, is
adapted to receive the spring coil in only one of two alternate
positions displaced 180 degrees from one another.
Therefore, when the spring coil, as is indicated in FIG. 1, is made
so that the cross bar 26 and the knot 28 share a common plane with
the central axis of the coil, and when, as later will be described,
the muzzles of the guns are arranged to receive the cross bars of
the coils to position them only crosswise of the cross slat 30 of
the slat frame 32, it is apparent that the position of the knot 28
at the upper end of the coil must be either on one side or the
other of the cross slat 30 or, stated with reference to the
direction of movement of the slat frame 32 through the apparatus,
must either be fore or aft, i.e., on the leading or trailing edge
of the spring.
I have found such orientation preferable to a number of kinds of
top face assembly of the box-spring construction, and as a matter
of practice, all of the springs of all but the last row are usually
positioned with their knots trailing with respect to the direction
of advancement through the assembly machine, the knots of the last
row of springs being presented with knots leading, so that each of
the peripheral springs presents a smooth unknotted edge of the top
convolution for tangential connection to an encircling border wire
or frame (not shown).
It is equally conceivable, however, that for some form of top-face
assembly of the construction, an orientation of the spring coil to
position its knots other than precisely leading or precisely
trailing may be preferred, in which event some other relative
rotative displacement of the cross bar 26 at the bottom end of the
coil and the knot 28 at the upper end of the coil may be preferred.
In any case, however, the chordal cross bar 26 at the bottom of the
coil serves as the reference from which the coil is positioned.
As will be noted from FIGS. 1 and 2, as well as other views, the
slat frame 32 comprises the leading end slat 30, narrower
intermediate cross slats 31, and a trailing end slat 33 (FIG. 8b
only). These are nailed to longitudinal side rails 34, the ends
slats 30 and 33 each having a second layer 30a and 33a in a common
plane with the side rails 34. In frames of greater width than the
twin-size frame shown, a center rail would also be provided.
The individual stapling guns 35 ganged for unison operation in the
assembly apparatus (FIGS. 4a and 4b), are powered by air, as is
conventional with commercial industrial staplers, and are arranged,
as will be apparent from FIG. 4a, in a line abreast upon a
vertically reciprocable carriage 36 which itself is powered to
travel between a retracted, lower, coil-loading position, shown in
FIG. 4a, and an upper or firing position, illustrated in FIG. 4b. A
particularly unique feature of the gun itself is that its muzzle is
equipped with a surrounding sleeve 38 which is preferably of a
slippery material such as Nylon, Teflon, or the like, is generally
cylindrical in shape and of a diameter slightly less than the minor
diameter of the cone coil, and is chamfered or cone shaped at its
upper end to facilitate the emplacement of the inverted cone coil
thereupon.
The small upper end of the sleeve 38 is provided with a diametrical
half-round groove 40 in which the aforementioned cross-bar 26 of
the minor end of the coil is seated. It will be apparent, then,
that when the bank of guns is in the loading position of FIG. 4a,
each gun is adapted to receive over its muzzle sleeve 38 one
inverted coil spring which may be positioned in one of two
positions at the discretion of the operator, i.e., with the knots
in one of two available positions displaced 180 degrees from one
another. It will further be apparent that if some orientation other
than a trailing or leading position of the knots were desired, the
same may be as well achieved by maintaining the same relative
orientation of knot 28 and cross bar 26 as is illustrated in FIG.
1, but changing the orientation of the grooved seat 40 in the
muzzle sleeve 38 of the stapling gun. Such change would necessarily
be limited to such rotative displacement of the grooved seat 40 as
would continue to insure that the staple would straddle the cross
bar 26.
In any event, the combination of the cross bar 26 at the bottom or
small end of the spring coil and the diametrical seat 40 on the
muzzle sleeve 38 of the gun serve to determine the rotative
displacement or orientation of the coil, and to maintain that
orientation while the coils rise from the loading position of FIG.
4a to the firing position of FIG. 4b.
The sequence of these several operations is indicated more or less
diagrammatically in FIG. 2. In FIG. 2, the inverted slat frame 32
is shown positioned for the connection thereto of the second row of
spring coils, a first row having previously been stapled to the end
or leading cross slat 30 of the slat frame. As earlier indicated,
the gun 35 in lowered position corresponding to that of FIG. 4a is
loaded with a spring coil 20 which is then elevated by upward
movement of the gun to the broken line position of FIG. 2 at which
the bottom convolution and the cross bar 26 of the spring are
pressed firmly into contact with the second cross slat 31 of the
base frame, and the upper or opposite side of that cross slat is
firmly bucked by a backing bar 42 which serves as an anvil on the
cross beam 44 against which to drive the staple into the slat.
The firing of the stapling gun 35 is preferably done with force
sufficient to impress or to indent the cross bar 26 at the bottom
end of the spring into the surface of the cross slats of the frame,
the impact of this force being sufficient also to cause a slight
bending of the cross bar in a vertical plane (See FIG. 1). The legs
46 of the staples 48 are preferably chisel-shaped so as to be bent
into a curved configuration upon entering the wood, thereby to
prevent their unintentional dislodgement, and to anchor the springs
20 securely in place.
The stapling accomplished, the guns are withdrawn, leaving their
spring coils secured to the frame.
As will be apparent from FIG. 2, as well as from FIGS. 3 and 4, the
stapling is performed with the springs 20 and the slat frame 32 in
an upside-down condition, thus to use the force of gravity to
maintain the desired orientation of the individual coil springs
with the muzzles 38 of the stapling guns.
ELEVATING AND FIRING THE STAPLING GUNS
The stapling mechanism, illustrating to the far left of FIG. 3 as
well as in FIGS. 4a and 4b and 5, is carried on a stationary frame,
which comprises a pair of spaced standards 50 which are weldments
of steel plate connected together at their upper ends by the cross
beam 44, which is of inverted T section, and at their lower ends by
cross bracing 52 of any suitable configuration. Above the lower
cross brace, the standards are also joined by a tubular manifold
54, which is connected to a source of pressure air, and to which
the individual stapling guns 35 are connected by suitable flexible
hoses 56, (FIG. 5) the manifold chamber having a volume sufficient
to ensure that the guns will be powered uniformly.
The guns themselves are mounted upon the reciprocable carriage 36
which includes a pair of slide members 58, one at each end of the
carriage, connected by a cross beam 60 upon which the stapling guns
are firmly clamped at uniform height in bolted pillow blocks 62.
Each slide member 58 is movable upon a vertical slide shaft 64 or
way which is secured in brackets 65 affixed to the adjacent
standard of the frame. Each slide 58 is provided on the side
opposite the operator's position with a rack 66 fixed thereon, and
each rack is engaged with a pinion 68 secured to a cross shaft 70
extending between, and journaled in bearings in, the opposed
standards 50 of the stationary frame. One end of the shaft 70, as
seen in FIG. 3 and at the left hand side of FIG. 4a, is provided
with a driven pinion 72 which is in turn engaged by a reciprocable
rack 74 connected to the piston rod of a double-acting air cylinder
76, the rack 74 being back on its side opposite its teeth by a
roller 77 to take the side thrust of the toothed engagement.
As will be seen by comparing FIGS. 3, 4 and 5, the extension of the
rack 74 by the driving cylinder 76 rotates the shaft 70, which,
through the pair of gears 68 engaged with the racks 66 fixed to the
slides 58 of the gun carriage, causes the guns 35 thereon to move
upwardly to the position of FIG. 4b to carry the springs 20 into
contact with the cross slats of the slat frame 32.
The guns are connected for unison firing by a common triggering bar
78 which is carried by and therefore moves with the gun carriage
36. The bar 78 is a square tube eccentrically mounted at its ends
in bearings 79 on the slide members 58 so that when rocked, one of
its corner edges engages the trigger 80 of each gun and causes the
guns to fire in unison. The trigger bar is rotated by means of a
double-acting air cylinder 81 mounted upon the carriage 36, and
connected to a crank 82 on the trigger bar, causing the bar to rock
when the piston of the firing cylinder is moved.
BUCKING THE SLAT FRAME WHILE STAPLING
As may be appreciated from FIGS. 1 and 2, the inverted slat frame
32 is not of itself equipped to resist unyieldingly the impact of
the staple because, when the guns are elevated to emplace the
inverted coils against the downward face of the inverted slat, the
then-upward surface of the slat would be out of contact with the
upper cross beam 44, and would be supported firmly only under the
longitudinal side rails 34 (and center rail when present) of the
base frame. (See FIG. 4,7). It is, accordingly, desirable to
transmit the firm support of the upper cross beam 44 directly to
the cross slats in order to buck the same when the guns 35 are
fired.
The backing bar 42 for bucking the cross slats, and the operating
mechanism therefor, are best shown in FIGS. 4a and 4b, and in FIGS.
6a and 6c. The backing bars 42 are two in number, one on either
side of the central feeding or indexing mechanism 83 by means of
which the slat frame 32 is advanced through the apparatus. Each
backing bar 42 is positioned in a slot 84 (FIG. 5a) in the flange
of the inverted cross beam 44, and by means of lugs 86 is
reciprocably mounted upon a pair of capped posts 88 each screwed
into the upper side of the girder flange. The backing bars 42 are
normally maintained in an upper or retracted position on the cross
beam 44 by means of compression springs 90 which encircle the posts
88. When retracted, the lower edges of the bars 42 provide ample
clearance for the passage therebeneath of the cross slats of the
slat frame 32 as the same are being advanced by the indexing
mechanism 83 with the ends of the cross slats 30 resting upon the
angle-iron frame ways 92 seen in section in FIGS. 4a and 4b, and in
side elevation in FIG. 2 and in the several FIGS. 6.
To bring the backing bars 42 into supporting contact with the upper
surface of a cross slat to resist the driving force of the staple,
four cam levers 94, two for each backing bar, are ganged to a
connecting rod 96 which in turn is pivotally connected to the
clevis of the piston rod of a double-acting air cylinder 98 mounted
at one end of the upper cross beam 44. As will quickly be seen from
cmparison of FIS. 4a and 4b (also 6a and 6c), the extension of the
piston rod of the cylinder causes the connecting rod 96 to move
from left to right, as there seen, rotating the several cam levers
94 clockwise to cam the backing bars 42 downwardly into backing
contact with the cross slat of the frame.
The drive cylinder 98 for the backing bars 42 is connected to the
operating valve that controls the drive cylinder 76 for elevating
the gun carriage, so that pressure air is admitted to both
simultaneously. However, inasmuch as the cylinder 98 is smaller in
diameter as well as stroke, it completes its movement before the
guns are fully elevated, assuring that the cross slat is solidly
backed for the arrival of the guns and therefore solidly bucked for
their firing.
Because the apparatus is adapted to be employed for the manufacture
of box springs that vary in width, i.e., to accommodate at least
the standard twin and double-bed widths, as well as others, the
ways 92 upon which the slat frame 32 advances through the apparatus
are adjustably mounted upon the flange of the cross beam 44, being
suspended therefrom on brackets 100 that are adjustably clamped to
the flange by means of set screws (FIG. 2). Similarly, to
accommodate the narrower widths of the twin-size frame, the backing
bar 42 is made adjustable in length by providing it with segmental
engaging elements or shoes 102, which are attached to the
reciprocable backing bar 42 by means of screws and which permit the
convenient removal of a sizeable portion of the engaging edges of
the bars to accommodate the twin size frame, or the complete
replacement and substitution of different shoes in the event that
other widths or slats arrangement of base frames is employed.
In a similar manner, the positions of the guns on the movable gun
36 can likewise be adjusted to control the intercoil spacing, as
may be desired to accommodate other than the major sizes of box
springs which will occupy the greater portion of the operating time
of the apparatus.
FEEDING THE SLAT FRAME TO THE STAPLING STATION
As is indicated generally in FIG. 3, a stack or magazine 103 of
prefabricated slat frames 32 is supported upon a scissors elevator
104 which is operated on call by hydraulic power to elevate the
stack of frames one frame thickness at a time to bring a new frame
to the level of the frame ways 92 and into the operating range of
the feed pawls of the indexing mechanism 83 after the preceding
frame has advanced sufficiently to clear the leading edge of the
stack. The stack elevator 104 is operated automatically by control
meansyet to be described.
The frame ways 92 extend from the magazine 103 to the stapling
station, being supported at their rearward ends, adjacent the feed
stack, by an upright frame comprising a pair of side columns 106
connected at their upper ends by upper cross beams 107 and 108, and
a lower cross beam 109.
Upper cross beam 108 and lower cross beam 109 are connected by
numerous vertical filler rails (not shown) which constitute an
abutment against which to emplace the stack 103 fo slat frames,
whose side edges are guided by posts 110 on the frame elevator 104.
They also support the control box 111.
The entering ends of the frame ways 92 are supported on a slide
shaft 112 secured in brackets near the upper ends of the columns
106, the connections of each way to the shaft 112 being made by a
bracket (not shown) that is secured to the way and adjustably
locked in place on the slide shaft 112 by a set screw.
As shown in FIG. 3, the frame ways 92 extend forwardly to the front
edge of the stapling mechanism support standards 50 from which
point the inverted slat frame, after having received its coils, is
transferred to extension ways (FIG. 8a only) from which to be
removed in any convenient manner for further operations.
The indexing mechanism 83 is the most complicated part of the
apparatus and is shown in FIGS. 3, 4, the several FIGS. 6, and also
in both FIGS. 8.
It consists essentially of double-acting double-ended air cylinder
114 whose reciprocable piston rod 116 is suitably extended and
fitted with three depending feed dogs or pawls 118, 120 and 122, of
which the pawl 118 is normally inoperative, being called into
operation only once for each frame to eject the frame from the
apparatus upon the completion of the stapling of a row of coils on
the last cross slat 33 of the frame.
As illustrated in FIG. 3, the drive cylinder 114 is mounted on the
back side of cross beam 44 of the stapling mechanism, i.e., on the
exiting side of the stapling station. At the rearward end of the
piston rod 116 of the drive cylinder 114 there is fitted a bracket
124 from which the intermediate feed pawl 120 is suspended, and
which also serves as a coupling for an extension rod 126 at the
extreme rearward end of which there is similarly mounted a
corresponding bracket 128 from which the rearward feed pawl 122 is
suspended. The extension rod 126 is supported in a slide bearing
107(a) in the upper cross beam 107.
At a suitable time in the operating cycle the valve controlling the
operation of the drive cylinder 114 is energized by the automatic
controller, causing the piston rod 116 to be extended to its
retracted position shown in FIG. 3, and then almost immediately, as
in a continuous operation, to move forwardly causing the
intermediate feed pawl 120 to engage a cross slat of the slat frame
then on the ways, and to move that cross slat forwardly to the
stapling station. At the same time, the rearward feed pawl 122
either assists in that feeding action during the time when both
pawls are operative upon a single frame, or at times causes the
rearward feed pawl 122 to engage a cross slat of the next frame of
the magazine 103 to move it onto the frame ways 92.
The intermediate and rearward feed pawls 120 and 122 are simply
bars pivoted on a horizontal axis in their respective mounting
brackets, chamfered at their front edges to match the generally
vertical rearward edges of the cross slats of the slat frame 32,
and urged by gravity to the operative position at which they are
stopped by the engagement of their rearward ends with an abutting
surface of their mounting brackets. Thus, on the rearward stroke of
the rod of the cylinder 114, the feed pawls 120 and 122 ride freely
over the next rearward cross slat of the frame, falling into
position poised for the next feed movement (See dotted line
position FIG. 6c).
That portion of the indexing mechanism which serves to position the
cross slat accurately for the receipt of a row of coils is shown in
detail in the several FIGS. 6. In FIG. 6a, the leading cross slat
30 of the frame, which is wider than all of the intermediate cross
slats 31 of the frame, is positioned at the stapling station to
receive its row of coils. The feed pawl 120, under the driving
force of the air cylinder 114, has moved the leading edge of the
slat frame firmly against a pair of positioning stops 130, each
adjustably secured to one of two rock shafts 132 journalled in
bearings on the upper side of the flange of the cross beam 44. The
rock shafts 132 are also shown in FIG. 7 which also illustrates the
torsion springs 134 by means of which the rock shafts are normally
biased to lift the stops 130 out of the frame-engaging position
(FIG. 6b). The rock shafts flank the indexing cylinder 114, and
each is rocked by its own separate crank 136 engaged by the cam end
of a push rod 138. The pair of push rods 138 flank the piston rod
116 of the cylinder 114, and extend through slide bearings in the
web of the T-shaped cross girder 44 to bearing blocks 140 secured
to sides of a central channel member 142 cantilevered rearwardly
from the web of the cross girder 44. The push rods 138 are
postioned so that their chamfered or cammed front ends are poised
to contact the roller of the rock-shaft crank 136 when the feed
mechanism is in the retracted position. On each push rod 138 there
is pinned a push block 144 which is normally engaged with the front
face of the bearing block 140, being urged into contact therewith
by a compression spring 146 surrounding the push rod between the
push block 144 and the web of the cross girder 44 (FIG.6b). In that
position, the cam end of the push rod is fully retracted and the
rock shaft 132 rotated by the torsion springs to remove the stop
130 from the path of the slat frame 32.
To place the stop 130 in operative position, the push rods 138 are
advanced to the position of FIGS. 6a and 6c, the cam ends of the
rods turning the cranks 136 to rotate the stop 130 to its depending
position at which to intercept the leading edge of the frame 32.
The push rods 138 are advanced by cross pins 148 extending
sidewardly from the bracket 124, which on the fully retracted
stroke of the piston rod 116, is positioned well to the rear of the
push blocks 144. The push blocks 144 are in sliding contact with
the sides of the support channel 142 to prevent the turning of the
rod 138 on its own axis while it reciprocates (Compare FIG. 4 and
6).
Thus on the return or working stroke of the piston 114 the
advancing feed pawl bracket 124 thrusts the push rods 138 forwardly
to move the reciprocable frame stops 130 from the position of FIG.
6b to the position of FIG. 6a, thus to form an abutment against
which the feed pawl 120 positions the leading cross slat of the
base frame.
The frame stops 130 are actuated on every feed stroke of the
machine, but as it depends from the rock shaft only sufficiently to
engage the upper layer 30a of only the leading cross slat, it is in
fact inoperative and of no consequence during the indexing of
subsequent cross slats 31 and 33 of the frame.
From FIG. 6b it will be apparent that the frame stop 130 is in the
stop position only during the last portion of the feed stroke of
the indexing mechanism inasmuch, as there is a considerable amount
of loss motion of the feed pawl bracket 124 before the push blocks
144 are engaged by the cross pins 148 (See FIG. 6b). This loss
motion permits the trailing slat 33 of the base frame (which is
also of double thickness) to clear the stapling station before the
frame stop 130 is again depressed to intercept the leading cross
slat 30 of the succeeding frame.
For the second and all succeeding cross slats of an individual base
frame, the upper frame stop 130, as earlier indicated, is
ineffective, and a second frame stop 150 is therefore provided,
insertable through a notch or slot 152 through the supporting
flange of the frame ways 92 from the under side thereof at the
appropriate time to intercept the forward edge of the second and
all succeeding cross slats of the frame. Its operation is
illustrated in each of FIGS. 6a, 6b and 6c, which together show not
only how the lower frame stop 150 serves its function, but also how
it is selectively disabled for the passage of the leading cross
slat 30 of the slat frame.
The lower frame stop 150 is shown in operative position in FIG. 6c
engaged with the forward edge of the second cross slat 31 which is
firmly seated against it by the intermediate feed pawl 120 of the
indexing mechanism. The lower frame stop is essentially hook-shaped
and pivotally mounted on the underside of the frame way 92 to be
rocked by a crank 154 into and out of frame-engaging position under
the influence of an air cylinder 156 mounted on a bracket 157
secured to the way 92. The stop-actuating cylinder 156 is
single-acting, having a self-contained spring (not shown) which
tends to extend the piston rod so as to retract or withdraw the
lower frame stop from engaging position. The cylinder is operated
by a solenoid valve under the influence of a normally open switch
158 which is mounted on the support channel 142 and positioned to
be operated by a cam bar 160 on the upper surface of the mounting
bracket 124 of the intermediate feed pawl 120. Under normal
conditions, therefore, when the mounting bracket 124 for the
intermediate feed pawl 120 has advanced sufficiently to cause its
upper cam bar 160 to depress the plunger of the control switch 158
of the frame-stop actuating cylinder, the frame stop 150 rises into
the frame ways to intercept the oncoming cross slat 31 of the base
frame. Conversely, as the feed pawl 120 retracts for another
indexing movement, the switch 158 is opened before the end of the
retraction stroke (dotted line position FIG. 6c) and the lower
frame stop 150 drops away to the position shown in FIG. 6b which it
maintains until, on the subsequent feed stroke, the cam bar 160
again actuates the switch 158 to apply air to the cylinder 156 and
to elevate the lower frame stop 150 into engaging position.
In order to disable the lower frame stop 150 for the positioning of
the leading cross slat 30, which is too wide to be serviced by the
lower stop, a second and normally closed switch 162 is mounted on
the upper side of the flange of the cross girder 44 with its
operator positioned to be intercepted by the upper portion 30a of
the leading cross slat of the frame. That switch is in series with
the normally open switch 158. When that switch is operated as
indicated in FIG. 6a, the switch 162 is opened, rendering it
impossible to close the control circuit to the valve controlling
the lower frame stop 150. Therefore, as long as the switch 162
indicates the presence of the leading cross slat 30, the lower
frame stops 150 remain inoperative, and the leading edge of the
frame advances to the upper stop 130.
Again, since the trailing cross slat 33 is the mirror image of the
leading slat 30, i.e., with the upper thickness thereof disposed at
the right-hand side or trailing edge of the last cross slat, it is
not in a position to actuate the switch 162 before the leading edge
of the trailing slat contacts the lower stop 150, and therefore is
of no effect in disabling the lower frame stop 150 for the
interception of the last or trailing cross slat 33 of the
frame.
ELEVATING THE FRAME STACK AND SPACING THE FRAMES
It will be apparent from FIG. 3 that as approximately one-half of a
slat frame has advanced through the stapling station, the trailing
edge of the frame will clear the supply stack 103. While the
uppermost frame is on the ways in transit to the stapling station,
one of its longitudinal side rails is followed on its then upper
surface by the depending operators of a pair of sensing switches
164 and 166 which are mounted on a bracket 168 secured to the frame
way 92, and spaced longitudinally of the direction of travel of the
slat frame through the apparatus, the rearward switch 166 being
disposed above the leading edge of the stack of frames 103, and the
forward switch 164 being positioned forwardly thereof above the
frame ways.
Both the sensing switches 164 and 166 are of the normally closed
type, and are wired in series with the elevator motor starter so
that the closing of both is required to call the elevator into
operation. Thus, when the slat frame in the frame ways in the
stapling apparatus clears the forward switch 164, a circuit is
finally completed through both switches, and the stack begins to
rise until the rearward switch 166 is once more operated to open
the circuit. The uppermost frame of the stack is then at the level
of the frame ways 92, and on the next indexing movement opens the
forward switch 164 as well.
It will be apparent from the foregoing that the spacing of the two
sensing switches 164 and 166 controls the spacing between
successive slat frames, which is set at a distance slightly in
excess of the normal interslat spacing so as to allow for the
greater width of the leading slats of the frame. As the increment
of movement is the length of the feed stroke of the indexing
mechanism, it will be apparent that the interframe spacing will be
the length of the feed stroke or some multiple thereof, determined
by the placement of the forward switch 164 along the frame way. One
feed stroke is sufficient for the purpose, which is in part to
permit the intermediate feed pawl 120 to drop into position behind
the last or trailing cross slat 33 of the frame so as to thrust it
forwardly to the stapling station. It will be apparent at the same
time that this necessary gap between successive frames establishes
the need for one indexing movement that is not accompanied by the
other steps of the normal operating cycle. For this purpose the
electrical control mechanism is arranged for manual operation of
each of the functions separately, so that the operator by actuating
the necessary switch, can effect one independent indexing movement,
advancing the leading slat of the succeeding frame into the
stapling station.
It is similarly necessary to preserve the interframe spacing at the
staping station for the discharge of the completed frame and the
arrival of the succeeding frame in order to provide clearance for
the lowering of the upper frame stop 130, i.e., because of the
necessity of inserting the stop 130 after the completed frame
clears the station, and before the succeeding frame arrives, it is
not possible to utilize the succeeding frame to push the completed
frame on its way. A separate ejector mechanism is therefore
provided at the exiting end of the apparatus.
EJECTING THE COMPLETED ASSEMBLY
The ejector pawl 118, as will be seen in FIG. 3, is a forward
extension of the indexing mechanism 83. Together with its
controller, it is shown in greater detail in FIG. 8, the pawl 118
also being seen in end view in FIG. 7.
Whereas the intermediate feed pawl 120 and the rear feed pawl 122
are urged by gravity to a depending operative position, always
either engaged with or poised for engagement with a frame cross
slat except during the retracting stroke, on which those slats are
overriden, the forward ejector pawl 118 is normally inoperative,
being lifted and maintained out of frame engaging position by a
small single-acting air cylinder 170. The pawl itself is pivotally
suspended from a bracket 172 affixed to the forward end of the
piston rod 116, and by its unbalanced weight is urged to the broken
line frame engaging position of FIG. 8a. It is also urged into that
position by a return spring (not shown) which is within and part of
the air cylinder 170 which is mounted on the forward face of the
pawl bracket 172 and has attached to its downwardly extending
piston rod a lifting arm 174 which is pivotally connected to the
pawl 118 by a pin-and-slot connection 176 within a recess 178
milled in the pawl forwardly of its main pivotal mounting. When the
air cylinder 170 is energized, therefore, the ejector pawl 118 is
lifted and maintained in its elevated position, where it remains
idle throughout the normal operation of the indexing mechanism, air
being constantly supplied to the cylinder 170 except when the last
or trailing cross slat 33 of the frame is positioned at the
stapling station (and fleetingly and ineffectively during the
arrival of the leading cross slat 30 at the stapling station).
The control of the forward ejector pawl 118 is effected by a small
air valve 180 through which pressure air is normally applied to the
cylinder 170. The valve is mounted on a bracket 182 screwed to the
flange of the cross beam 44 and positioned so that its operating
leaf 184 will be lifted by the upper layer 33a of the trailing
cross slat 33 when the latter is positioned at the stapling
station. When the valve is operated by lifting the operating leaf
184 the connection to the pressure source is interrupted and the
cylinder is vented to atmosphere through the valve body. Thus, when
the operating leaf is lifted to the dotted line position shown in
FIG. 8b, the feed pawl 118 is correspondingly depressed to the
broken-line, slat-engaging position of FIG. 8a, and remains so
poised for the indexing movement that completes the last stapling
cycle for a given frame. On the retraction stroke, the pawl 118
overrides and falls behind one of the intermediate cross slats 31
of the completed frame, and on the forward stroke removes it from
the stapling station.
Inasmuch as the upper layer 33a of the last cross slat 33 is in
engaging contact with the valve-operating leaf 184 for a distance
less than the length of the indexing stroke, pressure air is
re-admitted to the air cylinder before the ejection stroke of the
forward feed pawl 118 is completed. Thus, to maintain the
engagement of the ejector pawl 118 with the frame, the former is
provided with a forwardly extending lower lip 186 which maintains
the engagement of the ejector pawl with the cross slat with the
completed frame throughout the ejection stroke. If the extension
ways 188 (FIG. 8a only) are clear, the forward momentum of the
completed frame will disengage the cross slat from the ejector
pawl, permitting the air cylinder to raise it to the full line
position of the FIG. 8a. However, if an accumulation of completed
frames in the extension ways should not permit disengagement in
that manner, it will occur at the beginning of the next retraction
stroke of the indexing mechanism, the lifting force of the
cyclinder being inadequate to damage the mechanism.
Inasmuch as the valve 180 is operated by the passage thereunder of
the upper layer 33a of the trailing slat 33, it will be apparent
that it is similarly lifted by the upper layer 30a of the leading
slat 30, but only momentarily as will be apparent from comparison
of FIG. 6a, which illustrates the leading cross slat at the
stapling station, with FIG. 8b, which shows the trailing cross slat
similarly so positioned. Thus, the ejector pawl 118 is momentarily
but idly positioned in the broken-line position of FIG. 8a as the
intermediate feed pawl 120 moves the leading cross slat 30 into the
stapling station.
ELECTRICALLY CONTROLLING THE CYCLIC OPERATION
Central to the operation of the circuit is a motor-driven
industrial timer 111, the elements of which are enclosed within the
broken line of FIG. 9. They include a timing shaft 190 driven by a
motor 191 which is placed into operation by an initiating manual
switch 192 which is preferably a pedal-operated switch at the
operator's position in front of the stapling station, and a holding
switch 194 operated by a cam on the motor-driven shaft. The holding
switch continues to apply power to the driving motor when the
initiating manual switch 192 is released, holding the motor "in"
for essentially one revolution of the shaft after which the holding
switch 194 opens, de-energizes the motor, and thus determines the
length of an operating cycle.
On the same shaft 190 are three other cam-operated switches 196,
197, and 198 controlling respectively the solenoid valves 200, 201,
and 202 which control respectively the air cylinder 76 which
elevates the gun carriage, and with it the air cylinder 98 which
depresses the backing bars, the latter two being controlled in
common by the valve 200, the air cylinder 81 which rocks the
trigger bar to fire the guns, and the air cylinder 114 that powers
the indexing mechanism 83. The cam-operated or timing switches 196,
197 and 198 are each connected to their respective controlled
solenoid valves through one of three manually operated three-pole
switches 203, 204 and 205 the lower contacts of which must be
closed to render the automatic controller operative. A fourth
manually operated three-pole switch 206 serves essentially to
condition the slat frame magazine 103 for automatic operation.
It will be apparent from the diagram that the timing motor 191 is
connected to power through the lower set of contacts of each of the
aforementioned manually operated three-pole switches 203 to 206,
inclusive, requiring that all such contacts be closed before the
timing motor may be energized, and also that the circuit to the
timing motor is interrupted if any of those contacts should be
opened. A third set of contacts of each of the four triple-pole
switches 203, 204 and 205 operate signal lamps 207, 208, 209 and
210 to indicate that the timer switches 196, 197 and 198, the
elevator 104, and the timer motor 191 are conditioned for
operation.
It will be apparent then that when the cycle-initiating switch 192
is manually closed by the operator after he has closed each of the
aforementioned four triple-pole switches 203 to 206 inclusive, the
timer shaft 190 commences to turn causing, successively, the guns
35 to elevate as the backing bar 42 comes down, the trigger bar 78
to rock and to fire the guns, the guns to retract, and the slat
frame 32 to index in preparedness for the beginning of the next
cycle. Each of the air cylinders 76, 98, 81 and 114 controlling
these four basic movements is a double-acting cylinder and,
accordingly, the solenoid valve which controls each is a
two-position spring-return valve which normally applies pressure
air to one side of the operating piston while venting the other,
but reverses that condition when the controlling timer switches 196
to 198 are closed to power the valve solenoids.
The air cylinders 156 that operate the lower frame stops 150 are of
the single acting type, as earlier mentioned, and spring-biased to
retract the lower frame stops from their frame engaging positions
(FIG. 6b). The valve 212 which controls the cylinder 156 is itself
controlled by the earlier-mentioned normally closed switch 162
mounted on the upper surface of the cross beam 44. These two
switches, as shown in FIG. 9, are connected in series and when
closed cause the admission of pressure air to the cylinder 156 to
elevate the lower frame stop. As earlier pointed out, the normally
open 158 switch is closed after cross indexing stroke has proceeded
sufficiently to permit the preceding cros slat to clear the
stapling station, so that the lower stop 150 may resume its
position without obstruction.
The two normally closed switches 164 and 166, which energize the
drive motor of the hydraulic lift mechanism 104 of the frame
magazine 103, are connected in series to the drive motor through
the same set of contacts of the switch 206 that light the signal
lamp 210, the switch 206 thus interlocking the elevator 104 with
the timer motor 191. As earlier explained, the removal of one slat
frame from the top of the magazine 103 permits the switch 166 to
close, and when the trailing edge of that frame has finally cleared
the forward switch 164, the elevating motor is energized, lifting
the stack 103 until its uppermost frame again opens the rearward
switch 166. When the magazine empty and the last frame has also
cleared the forward switch 164 the elevator proceeds to its maximum
height at which point, with the hydraulic ram fully extended, its
pump bypasses until the operator shuts it off. This he does by
manually operating the triple pole switch 206, the middle contactor
of which is connected for double-throw operation, and applies power
to a solenoid to open a valve 214 which vents the hydraulic lift
cylinder to its sump permitting the elevator 104 to descend to be
recharged with a new stack.
Each of the solenoid valves 200, 201 and 202 may likewise be
operated individually by manual switches 216, 217, and 218
respectively, for testing and maintenance.
The entire control circuit is connected to power through a
double-pole single throw switch 219, both lines to which are
appropriately fused in accordance with conventional practice.
CONCLUSION
In the foregoing description, I have set forth what I believe to be
a full disclosure of a new method of fabricating box spring
assemblies by the stapling technique made possible in part by
modification of the spring coil for assembly to the slat frame by a
gun inserted axially through the interior of the spring. With this
spring and by this gun it is possible to secure the cone coil to
the box spring frame by means of a single staple and, if adequate
force be used in driving the staple, the spring can be locked
against rotational dislodgement by having its stapled part
impressed into the surface of the wood. This single staple
connection is sufficient, after the top face of the spring assembly
is united by whatever interlacing or joining technique may be
chosen, to maintain securely the connection of the smaller bottom
end of the spring coil to the wooden slat frame.
In the apparatus that I have provided for the practice of the
method, I have found it advantageous to employ the weight of the
individual coils as the method of maintaining their orientation
with the stapling gun and thus to perform the stapling with the
stapling guns pointed upwardly, and with the springs and the slat
frames upside down. The indexing mechanism by means of which the
slat frame is fed to the stapling apparatus one slat at a time is
such as to "square" the at at the stapling station to assure that
the springs are attached in a line parallel to the slat edges, and,
in the case of the intermediate slats, centrally thereof. This is
accomplished, notwithstanding any slightly skewed positioning of an
individual cross slat, by feeding the frame with a feed pawl that
engages the slat at or near the center of its trailing edge while
positioning the slat with two widely spaced abutments or stops that
engage the leading edge of the slat near its ends, and utilizing
sufficient feeding force to assure tight ultimate contact of the
slat with all three.
The features of my improved coil, assembly method, and apparatus
believed patentable are set forth in the appended claims.
* * * * *