Note: Descriptions are shown in the official language in which they were submitted.
3~
sackground o~ the Invention
In a machine for welding screens formed by lonyitudinal
screen wires welded to transverse rods or wires, the transverse
rods customarily are welded in succession to the longitudinal
wires at a welding station to and through which the longitudinal
wires are incrementally fed. The welding performed at the welding
station may be either fusion or resistance welding, during which
a transverse rod and the longitudinal wire or wires to which it is
being welded are clamped against relative movement by a suitable
means, which, as in my U.S. patent No. 4,~21,951 issued September
10 9, 1980, may be a ram or, as in Russian patent No. 322,243 of
February, 1972, may be an opposed pair of welding electrodes.
In one type of welding screen widely used ~or bo-th de
liquefying and particle sizing, the screen wires are of inverted
wedge-shape or otherwise downwardly tapered and conventionally are
disposed perpendicular to the transverse rods to which their bot-
toms or apices are welded. By contrast, my U.S. patent No.
4,221,951 discloses a mod.ification of its screen welding machine
for making screens having laterally til.ted screen wires. It is
to that part of the original disclosure that the present appli-
cation is particularly directed.
Summary of the Invention
The primary object of the pxesent invention is to pro-
vide an improved machine for welding screens and the like formed
of spaced longitudinal screen wires weldea at a welding station to
spaced transverse rods,whereby the longitudinal screen wires are
incrementally fed to and through a welding station and the trans-
verse rods are welded in succession to the longitudinal w.ires at
the welding station and the screen wires are laterally tilted in
--2--
advance oE the welding station for correspondinyly tilting the
wires longitudinally of the transverse rods when welded thereto.
~ nother object of the invention is to provide an improved
screen welding machine of the charac.ter described in the preceding
object, wherein the screen wires are guided to the welding sta-
tion at a predetermined lateral spacing and tilting by being
slidably received in advance of the welding station in correspond-
ingly laterally spaced and tilted slots in confronting end sur-
. faces of spacer means and means supporting and backing the screen
wires against forces exerted thereon by the spacer means.
A further object of the invention is to provide an im-
proved screen welding machine of the character described in the
immediately preceding object, wherein the spacer means is a verti-
cally reciprocable spacer plate and the support means is a platen
supporting and backing the screen wires against forces exerted
thereon not only by the spacer means but also in clamping a trans--
verse rod to the screen wires at the welding station.
Other objects and advantages of the invention will appear
hereinafter in the detailed description, be pointed out in the
appended claims, and be illustrated in the accompanying drawings,
in which:
Figure Description
Figure 1 is a perspective view of a preferred embodimen-t
of the improved screen welding machine of the present invention
with the ram in clamping position;
Figure 2 is a fragmentary side elevational view on an
enlarged scale of the machine of Figure 1 with the frame and other
parts removed to more clearly illustr~te certain of the details
of construction;
Figure 3 is a fragmentary side elevational view of the
structure of Figure 2 on a further e;nlarged scale ~ith the ram
and transfer clamp assembly in their advanced or welding positions
and with some portions broken away and shown in sect1on and others
added to more clearly illustrate certain of the details of con-
struction;
Figure 4 is a view similar to Pigure 3 but showing the
ram and transfer clamp assembly in positions for incremental ad- ;
vance of the longitudinal wires through the welding station;
Figure 5 is a fragmentary vertical sectional view on a
reduced scale taken along lines 5-5 of Figure 2;
~ igure 6 is a fragmentary vertical sectional view taken
along lines 6-6 of Figure 2; and
Figure 7 is a fragmentary vertical sectional view on an
enlarged scale taken along lines 7-7 o Figure 2, showing the
structure i.nvolved in adapting the machine of the present invention
to make welded screens having tilted screen wires.
Detailed Description
.
~ eferring now in detail to the drawings in which like
reference characters designate like parts, the improved welding
machine of the presen~t invention is adapted for making screens,
mats, or like weldments, hereinafter termed generally "screens",
which are formed of spaced longitudinal wires or rods welded to
spaced transverse rods, bars, or wires.
'' .
~ 4 -- .
- Designa-ted as 1, the improved machine has a welding station
2 at which spaced longitudinal wires or rods 3 are welded in se-
quence or succession to spaced transverse rods, bars, or wires 4.
Wbile the transverse rods 4 may be delivered to or suppliea a-t
the welding station 2 in any suitable manner, the longitudinal
wires 3 preferably are fed from the back to and pushed through the
welding station by a feeding device in the form of a transfer clamp
assembly 5 positioned in advance for engaging or clamping and in-
crementally feeding the longitudinal wires therethrough in incre-
10 ments predetermined by the desired lateral spacing of the trans- ;
verse rods in the finished screen. Although the trans~er clamp
assembly 5 may be employed for feeding the longitudinal wires 3 tc
the welding station 2, regardless of whether the welding performed
at the welding station is resistance or fusion welding, and the
improved machine 1 can be adapted for resistance welding by suit-
able modification of the welding means and associated structure
at the welding station, the illustrated machine is particularly
designed for fusion welding and will be so described as exemplary
of the invention.
The illustrated fusion weldlng machine is comprised of a
frame 6 moun-ting toward the front a stationary platen, bed, or
bed plate 7, and above the platen a press ram or pressure-applying
or clamping member 8 reciprocable vertically relative to the
platen between projected, advanced or down and retracted or up
positions for respectively pressing or clamping a workpiece against
the platen and releasing the workpiece. Generally resembling, in
its frame, platen and press ram, a press brake for bending or
otherwise forming metal sheets, the preferred machine 1 in these
respec~s is an adaptation of a 55-75 ton press brake currently
marke-ted by Houdaille Industries, Inc. under the trademark "Di-
Acro", in which the ram 8 is mounted in suitable guideways ~not
shown) on the frame 6, hydro-mechanically powered in its advance
and retract strokes, and precisely adjustable in its movement
relative to the platen 7. In the machine 1 the welding station 2
is the space in and adiacent to the opening or gap 9 between the
ram 8 and platen 7 through which the longitudinal wires 3 are in-
crementally fed and in which they are welded in succession to eachof the transverse rods 4. Exemplified in its products by a
welded screen for screening solids and liquid-solid mix-tures in
which the longitudinal wires 3 and transverse rods 4 are commonly
called, respectively, screen wires and tie rods, the improved
machine is particularly designed for welding a screen upside down
with the screen wires resting and supported directly on the upper
end of the platen 7 or, and preferably, on a wear or face plate or
lower die 10 removably mounted on tha-t end, and the tie rods 4
each in turn overlying and supported on the screen wires in posi-
tion to be pressed or clamped thereagainst by the ram 8.
With a body 11 in the form of a thick flat plate suitablyreinforced on its back 12 by horizontal and vertical reinforc.ing
ribbing 13, the preferred ram 8, for applying pressure to the tie
rods 4, carries or mounts a pressure plate or bar or upper die 14.
Inset in the front or face 15 of the ram 8 and depending from and
projecting below its body 11, the pressure plate has its lower or
tie rod-confronting end 16 notched, slotted, or configured over
-- 6
its length to conform to or accommodate the rounded, reckangular
or other configuration of the surface o~ the tie rod 4 presented
thereto. Releasably mounted, as by screwing or bolting, on the
ram 8 with its upper part seated for solid backing in a slot 17
therein, the pressure plate 14 may be unitary or sectional and be
bolted or otherwise releasably mounted either directly on the body
11 or, as illustrated, on a~ adapter or filler block 18 fitting in
and clamped to the body. In either case the pressure plate 14
is mounted against vertical movement relative to the ram 8 and pref-
erably is readily removable for replacement by any of a pluralityof interchangeable pressure plates having differently configured
lower ends 16 for accommodating tie rods 4 of different shapes and
sizes. The pressure plate 14 extends substantially the full width
of or is coterminous laterally with the ram 8 and the welding
station 2. Depending on the width of the welding station 2, which
suitably may be on the order of abou-t 7 or 8 ft. (2.13 or 2.44 m.),
and the length of the screen wires 3, the machine 1 is adaptable
in a single welding operation Eor welding a pair of wide screens
in tandem for later cutting apart or two such pa1rs of about half
or less of the maximum width so they can be welded simultaneously
- in and discharged abreast from the welding station. For slidably
receiving and guiding the screen wires 3 at the predetermined
lateral spacing through the welding station 2, as they are incre-
mentally pushed, movedl or fed forwardly therethrough by the trans-
fer clamp assembly 5~ a spacer or guide bar 19, mounted on or car-
ried by the ram 8 and projecting or extending below the pressure
plate 14, has its under, lower or wire-presented face or sur~ace
-- 7
- , !
20 interrupted b~ notches or slots 21 correspondiny in
configuration and lakeral spacing to but of less depth than the
screen wiresO
E~tending the full width of or coextensive or coterminous
laterally with the ram 8, and suitably of one piece or unitary
rather than seckional, the spacer bar 19 at the front engages or
abuts the back of the pressure plate 14 and the latter convenienkly
is apertured for therethrough bolting or otherwise releasably at-
taching the spacer bar ak the back to a slide plate 22 slidable
vertically on the back 12 of khe ram body 11 in and between guide
brackets 23 mounted on the body. A plurality of laterally spaced
compression coil springs 24 seated in the upper end of the slide
plate 22 and acting therebetween and an overlying backup bar or
.~ abutment 25~ through the slide plate,yieldably urges the spacer
bar 19 downwardly and not only enables the spacer bar 19 to handle
screen wires of different depth, but, in the down or clamp.ing
position of the ram 8 and so long as the springs are not fully
compressed, also ensures that the screen wires will be clamped by
.- .the spacer bar againsk the platen 7 independently of the action
and relative vertical position of the pressure plate 14 in clamp-
ing a tie rod 4 to the screen wires.
For limiking its upward movement relative to the ram and
prevenking the springs 24 from being fully compressed or going
solid, the spacer bar 19 is backed by a key 2~ inset in the front
of the slide plate 22 and normally spaced below and engageable with
an overlying shoulder or stop 27 on either the ram body 11 or, if
present, the adapter or filler block 18. With the slots 21
.
-- 8
shallower or of less dep-th than the screen wires 3, t~e sprin~s
24, preferably precompressed and further compressed by any down-
ward movement oE the ram 8 after the spacer bar 19 has clamped or
pressed the screen wires 3 against the platen 7, when the pressure
plate 14 has clamped the tie rod 4 to the screen wires under the
full force of the ram, which suitably may be around 120,000 p.s.i.
(8436.72 kg./sq. cm.), provide a spring force independent of the
ram force for clamping the screen wires against movement during
welding of a tie rod thereto. With the stroke or vertical movement
of the ram 8 between up and down positions usually only about 1/2
to 3/4 in. ~1.27 to 1.9 cm.), the spacer bar 19 preferably is
lost-motion connected to the ram for adjustable limited upward
movement on retraction thereof, suitably by smooth-shanked, end-
threaded adjusting bolts 25a on and adjacent opposite sides of the
backup bar 25 and extending vertically therebetween and th~ upper
end of the slide plate 22. This limited upward movement of the
spacer bar 19 with the ram 8 should be sufficien-t to release the
screen wires 3 from clamping by the spacer bar for substantially
resistance-free movement longltudinally relative thereto, while
retaining the screen wires somewhat loosely or with slight clear-
ance in the slots 21 for thereby restraining the screen wires
against canting or twisting and maintaining their lateral spacing
during such relative longitudinal movement. `As in the case of
the pressure plate 14, the removable mounting of the spacer bar 19
on the slide plate 22 permits interchange with like spacer bars
having differently slotted or configured underfaces or lower end
portions 20 to suit screen wires 3 of different sizes and shapes,
such as the spa-cer bar for angled screen wires shown in Fig. 7.
g
In addi-tion to the slotting of the spacer bar 19 for
receiving and laterally spacing the screen wires 3, if, as
claimed in this application, the screen wlres are to be tilted
relative to the tie rods 4, as shown in Fig. 7 and disclosed for
a slurry screen in my IJ.S. patant No. 4,193,503 issued March 18,
1980, not only will the slots 21 in the spacer bar be tilted but
the screen wires preferably will seat at their then bottoms in
correspondingly tilted grooves, notches or slots 28 in the wear
or face plate lO of the platen 7.
Positioned or located rearwardly or in advance of or
beyond the welding station 2, the transfer clamp or feed assembly
5 by which the screen wires 3 are incrementally pushed or fed for-
wardly to the weldin~ station in increments predetermined by the
desired lateral spacing between the tie rods 4, is comprised of
lower and upper jaws 29 and 30, respectively, the lower jaw hori-
zontally reciprocable, normal or perpendicular to the ram 8 and
welding station and parallel to the screen wires, and the upper
jaw mounted, carried, or supported on the lower jaw for vertical
reciprocation or movement relative thereto. Suitably a thick,
generally flat plate, of substantially the same wi.dth as the
welding station 2, the .lower jaw 29 preferably is horizontally
slidable on a pair of coplanar parallel laterally spaced support
shafts 31, each at the front fitting or received in and supported
by the platen 7 and at the rear clamped against movement in and
supported by a bifurcated support block 32, in turn supported on
a crossbeam 33 extending between and connecting the sides 34 of
the frame 6. For suitably round shafts 31, the lower jaw or
~ 10 --
carrier plate 29 has bolted to and depending ~rom its underside or
bottom 35 adjacent opposite sides thereo~ pairs of longitudinally
or axially spaced pillow blocks 36, which, for minimal friction,
desirably have as bushings 34 so-called 'iSUPER" hall bushings
marketed by Thompson Industries, Inc.
Mounted toward the front on and coextensive laterally with
the lower jaw 29, the upper jaw 30 suitably is guided adjacent both
sides in its vertical movement by guideposts 38, fixed to and
upstanding from the lower jaw and sliding in suitably bronze bush~
:.10 ings 39 fitted in vertical apertures 40 in the upper jaw. For
vertically moving or reciprocating the upper jaw 30, the lower jaw
29 mounts on its underside 35 towards opposite sides and outwardly
of the adjoining pillow blocks 36, a pair of vertically acting,
i fluid and preferably hydraulic cylinders or power units 41, the
~piston rods 42 of which extend upwardly through the upper jaw 30
adjacent and inwardly of the guidepost apertures 40 and are thread-.
edly received in the upper jaw 30 for transmitting or applying bot~
upward or retract and downward or advance vertical movement thereto
from the cylinders 41. The piston rods 42, after being turned for
predetermining the limits of vertical movement of the upper jaw 30,
are locked in position by lock nuts 43~
Undercut toward the front on its upper face 44 for fixedly ~.
receiving a wear or face plate 45 upstanding above that face and
at the top suitably ~lat and on the level of or coplanar with the
-~ top or top surface of the platen wear plate 10, the lower jaw 29
is reciprocated, shifted, or moved horizontally on and longitudi-
.nally of the guide or support shafts 31 by fluid and preferably
hydraulic cylinders or po~er units 46 acting horizontall~ parallel
to the shafts on the back of the lo~er jaw adjacen-t opposite sides
thereof an~ each preferably mounted for axial or longitudinal ad-
justment in position on the adjoining side 34 of the frame 6. With
the free or outer ends of their piston rods 47 screwed into or
otherwise suitably connected to the lower jaw 29, the cylinders 46
are adapted to shift or move the lower jaw and therewith the upper
jaw 30, both to~lard and away from the welding station 2, as well
as to predetermine by the length of their stroke the limit of for-
ward movement and thus the advanced or forward position of thejaws, while an adjustable rear stop 48, conveniently mounted on a
mounting block 49 on the crossbeam 33 and engageable with the back
of the lower jaw, serves to predetermine the extent of the rearward
or retract movement and thus the retracted position of the lower
jaw and the rearward position of-both jaws.
Engaging and slidably supporting the screen wires 3 on the
wear plate 45 on the lower jaw 29, the transfer clamp assemhly 5
in the down position of the upper jaw 30 clamps the screen wires
- between the wear plate and a polyurethane or a like suitable
`~ 20 resilient pad 50, dovetail-mounted on the bottom or lower end
of the upper jaw by and projecting below front and rear mounting
blocks, 51 and 52, respectively, screwed or bolted, as appropriate,
to the upper jaw. Conversely, when the upper jaw 30 is shifted,
moved or retracted -to its retracted or up position, the resilient
pad 50 thereon preferably is disengaged or free from and spaced
somewhat above the screen ~ires 3. Altnough not usually necessar~,
the front mounting bloc}~ 51, if desired, can be slotted in
12
correspondence with the slotting of the spacer bar 19 on the ram
8 for assisting the spacer bar in spacing and guiding the screen
wires 3. T withstand the compressive stresses to which they are
subjected, the lower and upper jaws 29 and 30 are rein~orced at
the back, the upper jaw sufficiently by a single so-called
"burnout" or reinforcing plate 53 upstanding from and centered
laterally on and extending longitudinally of and welded to that
jaw and the lower ja~ by a pair of such plates 54 depending from
and welded to the underside 35 of that jaw beyond opposite ends
of the wear plate 45 and apertured to pass the support shafts 31.
In the illustrated machine 1 in which the tie rods are
~usion welded in succession to the screen wires 3 at the welding
station 2, the welding is performed by a welding assembly 55 con-
veniently mounted on the face or front 15 of the body 11 of the
ram g above the pressure plate 1~. The welding assembly 55 in-
cludes a torch 56 which may be adapted Eor fusing the tie rods A
to the screen w.ires 3 by more exotic media, such as laser beams or
plasma, but usually will be suited ~or either TIG or MIG welding,
the former using a nonconsumable electrode, such as tungsten, and
the latter a consumable electrode and both directing an inert gas,
such as argon, at the areas being welded ~or preventing oxidation.
While TIG welding usually is preferred, for low strength screens
having small, narrowly spaced screen wires 3, the weld beads
formed across the screen wires in MIG welding by the consumable
electrode, may serve as cross-ties in place of the usual tie rods
4.
Whatever the form of the fusiorl welding, if the welds
between the screen wires 3 and tie rods 4 in a finished screen are
to be uniform, it is necessary khat the torch 53 be so mounted and
driven as to traverse the ram a at a;precise speed and in a recti-
linear path precisely parallel to the lower end 16 of the pressure
plate 14 and thus a tie rod 4 clamped in welding position at the
welding station 2 and that both the speed of the traverse and po-
sitions of the torch be adjustable or variable for welding screens
from screen wires and tie rods of different sizes and shapes. To
the above ends, if the face 15 o~ the ram body 11 is uneven or ir-
regular, a planar I(lounting surface 57 parallel to the pressure
plate 14, is machined in the lower portion of that face for mount-
ing horizontally or laterally spaced pairs of vertically spaced
supports 58 on which are mounted vertically spaced, parallel, suit-
ably round, guide shafts, rails or ways 59 ex-tending horizontally
across the ram body. In turn, the guide shafts 59 slidably mount,
- preferably through a pair of horizontally spaced open Thompson
roller bushlng plllow blocks 60 on each shaft, a horizontally
shiftable or slidable torch carriage or carrier 61
Mounted on or carried by the carriage 61 for therewith
horizontally traversing or tracking across the ram 8, the torch
56 is so connected to the carriage as to be adjustable vertically
relative thereto and also in its spacing from and vertical angular
disposition relative to the welding station 2, the connection 62
- suitably including a first or upper slide or slide plate 63
slidably mounted on and shiftable vertically relatlve to the car-
riage, a second or lower slide or sli.de plate 64 angled downwardly
~ 14
toward the weldin~ s-tation 2 and connected for relative vertical
pivoting through a limited arc to the lower end of the first slide
plate, and an angle bracket or mouni 65 directly mounting the torch
and mounted on the lower slide for l;ongitudinal sliding or shifting
relative thereto. With manually adjustable screw or like precision
drives 66 for adjusting the vertical position of the upper plate
63 relative to the carriage 61 and the longitudinal position of the
angle bracket 65 relative to the lower slide 64 and the relative
angular dispositions of the upper and lower slides adjustable
through an arcuately slotted plate 67 fixed to the upper slide, the
torch 56 is adjustable both vertically and longitudinally or axi-
ally and in its vertical angular disposition relative to the weld-
ing station 2 as best suits the sizes and shapes of the screen
wires 3 and tie rods 4 of the particular screen being welded or
fabricated.
For driving the torch carriage 61 on the guide shafts 59,
the welding assembly 55 has mounted on a track 68 fixed to the
face 15 of the ram 8 above and parallel to the guide shafts, a re-
versible, variable speed drive or tractor unit 65, rack-and pinion
~ or otherwise suitably drivably connected to the track. To avoid
machining of the part of the face 15 of the ram 8 on which the
track 68 is mounted, and still prevent transmission to the torch
carriage 61 of any horizontal angling of the drive unit 69 due to
irregularities in the mounting surface, the drive unit preferably
is drivably connected to the torch carriage by laterally spaced
vertical drive pins or bolts 70 depending or proje~ting downwardly
from the drive unit adjacent opposite ends thereof and each fitting
or received in an outwardly opening slo-t 71 elongated
perpendicular or normal to the ram face 15 and formed in one of
a pair of correspondingly spaced connecting brackets 72 on the
torch carriage.
Electrically controlled and fitted or equipped with suit-
able electrical and fluid circuits and components (not shown) for
operating its various moving parts in timed sequence, the welding
machine 1 is adapted for either automatic operation or selective
manual control through control panels 73 of which those involved
in selective control preferably are conveniently mounted on the
drive unit 69 for ready access by an operator observing the pro-
gress of the welding.
Preparation or readying of the machine 1 for a welding
operation in which one or more screens are to be welded, fabri-
cated or made of spaced longitudinal screen wires 3 and spaced
; transverse tie rods 4, entails selecting screen wires and tie rods
of the materials and sizes and shapes desired in the finished
screen or screens and, as necessary to suit the se]ected screen
wires and tie rods, exchanging the pressure plate 14 and spacer bar
19 for interchangeable replacements, ad~usting the strokes or
limits of movement of the ram 8 and lower and upper jaws 29 and 30
of the transfer clamp or feed or feeding assembly 5 and the dispo-
sition and traversing speed of the selected welding torch 56, and,
with the ram and both jaws in their retracted positions, manually
or otherwise inserting the selected screen wires from the back or
behind through the slots 21 in the spacer bar and into the welding
station, suitably with their leading ends substantially flush with
the front of the pressure plate.
With the screen wires 3 in place and the ram 8 and both
jaws 29 and 30 ini~ially in their retracted posi~ions r the welding
operation begins with a first welding cycle in which the upper
jaw 30 is first advanced to clamping position for clamping the
screen wires therebetween and the lower jaw 29 and the lower jaw
is then shifted or moved to forward position for pushing or feed-
ing forwardly through the welding station 2 a longitudinal incre-
ment of the screen wires predetermined by the desired lateral
,spacing of the tie rods 4 in the inished screen. Next, a tie rod
4 is placed or positioned in the welding station 2 over and across
the screen wires 3, followed by advancing the ram 8 to clamp the
tie rod against the screen wires and the latter against the platen
7 under the full force of the ram. Concurrently, the advance of
the ram 8 enables the spacer bar 19 to separately clamp the screen
wires yieldably to the platen 7 under the force of the springs 24
and independently of the force of the ram.
`- With the tie rods 4 and screen wires 3 now clamped against
movement jointly by the pressure plate 14, spacer bar 19 and jaws
29 and 30, the welding torch 56 is fired and from one side tra-
versed on the carriage 61 and by the drive unit 69 across the
screen wires and along the tie rod for welding them to each other
at their intersections. At the end of this welding step, the weld-
ing torch 56 is shut off and returned to initial position. There-
after, with the ram 8 still in its advanced position and the wires
3 clamped against either backward or other relative movement by
both the pressure plate 14 and the spacer bar 19, in sequence -the
upper jaw 30 of the feed assembly 5 is retracted to release the
screen wires and the lower jaw is retrac-ted -to initial position.
Only after the screen wires 3 are again clamped between the jaws
29 and 30, is the ram 8 retracted for releasing or freeing the
screen wires for their next incremental advance or forward feeding
through the welding station 2 under the pushing force of the feed
assembly. In the continuation of the welding operation, the weld-
ing cycle is repeated as often as necessary to weld the intended
number of screens from the screen wires initially inserted in the
machine 1.
Always clamped throughout the welding operation by either
`or both of the ram 8 and the feed assembly S, the screen wires 3
have no opportunity for free movement, with consequent assurance
of uniformity in the relative dispositions of the screen wires and
tie rods and the welds therebetween in the finished screens. Also,
by adding a second welding torch ~56 mounted on a separate carriage
61 connected for sliding in unison with the irst carriage on the
same guide shafts 59 and for drive by the same drive unit 69, and
spacing the torches such that each covers approximately half the
width of the welding station 2, since the welding step is by far
the longest in a welding cycle, the output of the machine can be
drastically increased, whether it is welding wide screens or simul-
taneously welding ahreast relatively narrow screens.
It should be understood that the described and disclosed
embodiment is merely exemplary of the invention and that all modi-
fications are intended to be included that do not depart from the
spirit of the invention and the scope of the appended claims.
- 18
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