Note: Descriptions are shown in the official language in which they were submitted.
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OPHTHALMIC SURGICAL INSTRUMENT WITH PRE-SET TIP-TO-SHELL ORIENTATION
BACKGROUND
[0001] The present invention relates to an ophthalmic surgical instrument
with
components facilitating clocked orientation of a surgical tip to its outer
shell/handle, and
components facilitating dimensionally-accurate manufacture including defect-
free
welding.
[00021 Ophthalmic surgical instruments are highly refined medical tools
used in eye
surgery, such as for cataract lens extraction. Such products are commercially
manufactured and available, such as from Alcon company, including for example
the
Infinity' Vision System and/or Ozil. Vision System. It is important that the
surgical
instrument that contacts the patient and that is handled by the surgeon be of
the highest
quality, since the human eye is a delicate organ and the surgical procedure is
very
delicate. Therefore, reliability, durability, safety, ease of use, ease of
sterilization, and
numerous other aspects of the surgical instrument and related methods are very
important. Also, physicians demand high quality and appealing aesthetics. At
the same
time, cost and manufacturability is important.
[0003] One tip used with hand-held ophthalmic surgical instruments is a
replaceable tip,
such as a phaco tip, with a straight end with beveled tip end, or a slightly
bent/curved
end with oriented tip end. Surgeons prefer that the bent/beveled end have a
particular
orientation relative to the handle when the surgeon picks up the instrument,
so that the
surgeon does not have to look to see the orientation of the bent/beveled end.
In other
words, surgeons want to intuitively known which way the bent/beveled end is
"facing"
when they pick up the instrument based on feel. The relative rotational
orientation of
parts is referred to herein as "clocking". Threaded connections provide an
inconsistent
angular rotational position (i.e. inconsistent 'clocking"), particularly when
torqued to a
desired preload. Preloading is a requirement for these tips, since the
instruments
sonically vibrate the tips during use, and a significant torsional preload is
required to
prevent unacceptable risk of loosening during use. Depending on the design,
the
instrument may have multiple threaded connections for supporting the tip (e.g.
a tip
threaded into a horn, and also the horn threaded Into a support shaft and/or
to the
handle/shell). Multiple threaded connections further amplify the problem of
inconsistent
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"clocking" of the bent/beveled end to the instrument's handle/shell.
Specifically, the
combination of the threads, the preloads, and tolerance stack-up of the
multiple
components of the instruments makes it difficult to predict exactly what
direction a
bent,/beveled end may face in a fully assembled instrument, thus resulting in
an
unacceptable number of bent/beveled tip ends being oriented outside a
preferred
angular range.
100041 Some existing manufacturing processes and Instrument designs attempt
to deal
with this clocking problem by replacing one or more of the threaded
connection(s) with a
press-fit arrangement, where the final clocked rotational position of the
bent/beveled
end (and/or of Interconnected components affecting clocking of the
bent/beveled end) is
set by a press-fit process. However, press-fit assembly processes do not
provide a
strength, robustness, and durability of threaded connections. Further, the
tips must be
replaceable, which press-fit does not support. Still further, standard
existing tips include
threaded connections, so it is difficult to eliminate the use of threads,
since the industry
presently uses them. Nonetheless, it is potentially a significant advantage to
provide
features and/or characteristics that result in components pre-set at the
factory to have a
particular clocked orientation when assembled, such as at a supplier's site,
rather than
requiring this be done at the overall system equipment manufacturer/assembler.
[00051 The handset in the present ophthalmic surgical instrument includes
several
components made of titanium that are fixedly connected by welding. Though
titanium is
a preferred material for the present handset, titanium is difficult to weld In
a defect-free
manner. At the same time, surgical handsets must be made defect-free so as to
avoid any
cracks, crevices, or imperfections that might harbor germs and unwanted
organics and
contaminants. Notably, defects in handsets can cause an Increase In
sterilization time
and/or frustrate optimal sterilization. Also, defective handsets can have
appearance
issues causing surgeons to object to or misinterpret the handset's quality.
100061 In addition to high standards for defect-free handsets, ophthalmic
handsets also
have high standards for dimensional consistency and accuracy. Further, the
handsets
must be light in weight to facilitate easy and non-tiring use by the surgeon,
Also, it is
preferable that the handsets use a minimum of materials to reduce
manufacturing cost.
This leads to a dilemma where the handset's outer shell must preferably be
thin-walled,
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yet thin walls can cause secondary problems. For example, some instrument
designs
require a thin-walled outer shell (such as an extruded thin-walled outer
shell) welded to a
machined tip. However, it is difficult to weld onto thin walls without
distortion (due to
the heat required for good welding, and/or issues related to non-uniform
heating and
later cooling), thus leading to welding defects and/or dimensional defects,
especially near
the weld area.
[0007] Thus, improvements are desired that positively affect each, any and
all of the
above items.
SUMMARY OF THE PRESENT INVENTION
[0008] In one aspect of the present invention, an internal subassembly for
an ophthalmic
surgical Instrument comprises a multi-diameter shaft, a horn fixedly threaded
into the
shaft and that is constructed to provide sonic vibration energy to an end
opposite the
shaft, a surgical tip for ophthalmic surgery including a tip end at one end
and a threaded
end threadably engaging the horn opposite the shaft, the tip end defining a
face
direction, a plug on the shaft, and a flange with an angle-locating feature.
The
subassembly further includes weld material holding the plug on the shaft in a
selected
angular and longitudinal position with the angle-locating feature having a
predetermined
angular clocked relation to the face direction of the tip end.
[0009] In a narrower form, the angle-locating feature is a recess in an
annular flange on
the plug.
[0010] In another aspect of the present invention, an ophthalmic surgical
instrument is
provided that includes a second outer subassembly Including a tubular shell
and an
irrigation tube attached to a side of the shell. The Instrument includes the
internal
subassembly, as described above, assembled into the second outer subassembly
with the
recess engaging the irrigation tube on the annular flange of the plug, thus
causing the tip
end to be in a desired angular clocked position relative to the irrigation
tube on the shell.
[0011] In another aspect of the present invention, a method of
manufacturing an
internal subassembly for an ophthalmic surgical instrument comprises providing
a multi-
diameter shaft, providing a horn adapted to generate sonic vibration energy,
fixedly
threading the horn and the shaft together, providing a surgical tip for
ophthalmic surgery
including a tip end at one end and a threaded end, threadably engaging the tip
into the
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horn opposite the shaft, the tip end defining a face direction, providing a
plug on the
shaft and a flange with an angle-locating feature, and welding the plug to the
shaft in a
selected angular and longitudinal position with the angle-locating feature
having a
predetermined angular clocked relation to the face direction of the tip end.
[0012) In a narrower form, the angle-locating feature is a recess in an
annular flange on
the plug, and wherein the step of welding the plug Includes engaging the
recess with a
feature in a welding holding fixture.
[0013] In a narrower form, the method includes providing a second outer
subassembly
having a tubular shell and an irrigation tube attached to a side of the shell,
and including
assembling the Internal subassembly above into the second outer subassembly
with the
recess engaging the irrigation tube on the annular flange of the plug, thus
causing the tip
end to be in a desired angular clocked position relative to the irrigation
tube on the shell.
10014] In one aspect of the present invention, an ophthalmic surgical
instrument
comprises a combination including a tubular shell having a tip end portion and
a tail end
portion, and further having a channel extending from a hole into the tubular
shell near
the tip end portion and extending to the tail end portion; and an irrigation
tube
configured to matably engage the channel with a forward end shaped to dive
into the
hole and with a rear end extending at least to the tail end portion. The
channel has a
narrowed region shaped to facilitate initiation of a laser welding process by
providing
abutting contact between the tubular shell and irrigation tube that, in turn,
provides
access and point-focused heating from a laser beam welding operation, thereby
facilitating heating and flowing of the material from the tubular shell into
welded
bonding contact with the irrigation tube with minimized physical and aesthetic
defects
and imperfections, yet without addition of separate welding material.
[0015j In a narrower form, the narrowed region includes deformed material
of the shell
that is deformed and pinched inwardly.
(0016) In another aspect of the present invention, a method of
manufacturing an
ophthalmic surgical instrument comprising steps of providing a tubular shell
having a tip
end portion and a tail end portion, and further having a channel extending
from a hole
into the tubular shell near the tip end portion and extending to the tail end
portion,
providing an irrigation tube shaped to matably engage the channel, and matably
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engaging the irrigation tube with the channel with a forward end of the tube
positioned
in the hole and a rear end of the tube extending to the tail end portion. The
method
further includes welding the tubular shell to the irrigation tube on both
sides of the
channel and for a length of the channel using material from the tubular shell
and
Irrigation tube, the step of welding specifically not using separately added
welding
material, such as welding wire.
[0017] in a narrower form of the invention, the channel has a narrowed
region shaped to
abutting contact with the irrigation tube when the tube is placed in the
channel, the
narrowed region facilitating initiation of a laser welding process by
providing access and
point-focused heating from a laser beam welding operation, thereby
facilitating heating
and flowing of the material from the tubular shell into welded bonding contact
with the
irrigation tube with minimized physical and aesthetic defects and
imperfections, yet
without addition of separate welding material.
[00181 In still narrower form, the method Includes deforming material of
the shell to
form the narrowed region by pinching and deforming material of the shell
inwardly at the
narrowed region.
[0019] In yet a narrower form, the step of pinching and deforming includes
forming the
narrowed region with two opposing embossments forming a butterfly-like shape
with
narrower portions nears center of the channel and wider portions on outboard
edges of
the narrower portions.
[0020] In one aspect of the present invention, an article for manufacturing
an ophthalmic
surgical instrument comprises a unitary metal rod blank made of continuous and
contiguous material and that includes a unitary body and a tip end portion and
a tall end
portion. The tip end portion tapers from a diameter of the body to a narrowed
tip
dimension and is designed to support a sonically-vibrating tip extending
longitudinally
from the tip end portion, The tail end portion tapers from the diameter of the
body to an =
increased tail dimension. The body and the tail end portion are a solid non-
tubular metal
rod of titanium material, but the tip end portion is machined to include a
multi-diameter-
defining Internal cavity comprising a first section defining an end-adjacent
first diameter,
a second section defining a second diameter adjacent the first section, and a
third section
defining a third diameter adjacent the second section, with the second
diameter being
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larger than the first and third diameters, such that the tip end portion
facilitates and
supports a sonically-vibrating tip. The metal rod blank is constructed to be
machined to
form a longitudinal bore through its length and also to be welded while
maintaining a
very accurate dimensional shape prior to being machined to form the
longitudinal bore.
[0021] In a narrower aspect, the blank further has a hole in its tip end
portion and a
channel in an outer surface of at least the body and the tail end portion ,
the channel
extending from the hole to the tail end portion.
[0022] In another aspect of the present invention, a method of
manufacturing an
ophthalmic surgical instrument comprises steps of providing a unitary tubular
blank
made of continuous and contiguous material and that includes a unitary body
and a tip
end portion and a tail end portion, with the body and the tail end portion
being a solid
non-tubular metal rod of titanium material, forming the tip end portion to
form a taper
from a diameter of the body to a narrowed tip dimension and so that the tip
end portion
is adapted to operably support a sonically-vibrating tip extending
longitudinally from the
tip end portion, and forming the tail end portion to form a taper from the
diameter of
the body to an increased tall dimension. The method further includes machining
the tip
end portion to include a multi-diameter-defining internal cavity comprising a
first section
defining an end-adjacent first diameter, a second section defining a second
diameter
adjacent the first section, and a third section defining a third diameter
adjacent the
second section, with the second diameter being larger than the first and third
diameters,
such that the tip facilitates and supports a sonically-vibrating tip end. The
non-tubular
metal rod is constructed to be machined to form a longitudinal bore through
its length
and also be welded while maintaining a very accurate dimensional shape.
[0023] In a narrower form, the method includes machining a longitudinal
cavity through
the rod, the longitudinal cavity including the internal cavity.
10024] In a narrower form, the method includes forming a channel in an
outside surface
of the blank that extends from a hole in the tip end portion to the tail end
portion.
[0025] In a narrower form, the method includes steps of providing an
irrigation tube
shaped to matably engage the channel, matably engaging the irrigation tube
with the
channel with a forward end of the tube positioned in the hole and a rear end
of the tube
extending to the tail end portion, and welding the tubular shell to the
irrigation tube on
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both sides of the channel and for a length of the channel using material from
the tubular
shell and irrigation tube.
[0026] An object of the present invention is to provide an ophthalmic
surgical instrument
and method of manufacture where the instrument includes a tubular shell with
channel
and mating irrigation tube attached along a side of the shell, but where the
tubular shell
Is initially made from a one-piece continuous and contiguous titanium metal
rod
machined at a tip end portion to include a multi-diameter cavity for
supporting a
sonically-vibrating tip. A remainder of the rod Is not initially machined,
which eliminates
problems of alignment and dimensional distortion caused by secondary
operations such
as welding, but Instead is machined later In the secondary processes, such as
after
welding. The present innovation eliminates the need to perfectly align and
then weld a
machined tip end to an end of a thin-walled tubular shell, thus avoiding
considerable
process control and quality issues.
[00771 These and other aspects, objects, and features of the present
invention will be
understood and appreciated by those skilled in the art upon studying the
following
specification, claims, and appended drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0028] Figs. 1-2 are perspective and exploded side views of an ophthalmic
surgical
instrument's handset with tubular outer shell and welded exterior Irrigation
tube and
clocked internal components, embodying the present Invention.
[0029] Fig. 3 is a side view of the tubular shell from Fig. showing a
side with the tube-
receiving exterior channel for receiving the irrigation tube.
[0030] Figs. 4 and 4A are exploded side and exploded perspective views
like Fig. 2 but
showing only the internal subassembly of the tip, the horn, the multi-diameter
shaft, and
the plug.
[0031] Fig. 5 is a perspective view showing assembly of the shaft to the
horn from Fig. 4
using a torque wrench and fixture.
[0032] Figs. 6-7 are perspective and side views showing components from
Fig. 5
threaded together with a tip to form a first subassembly (i.e. a preassembled
tip and
horn and shaft) and a plug rotatably supported on the first subassembly, all
positioned in
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a welding fixture for holding the first subassembly (and the tip) in a
specific clocked
position relative to a notch in the plug, the fixture facilitating welding of
the plug to the
first subassembly in known clocked orientation.
[0033] Fig. 8 is a perspective photograph showing a completed welded
assembly of the
first subassembly from Fig. 6 (i.e. the tip, horn, shaft, and plug) with the
plug welded to
the shaft.
[0034] Fig. 9 is a partial cross-section taken along line IX-IX in Fig. 3.
[0035] Figs. 10-11 are side views of a rod blank (i.e. rod) of unitary,
continuous, and
continuous titanium material (i.e. a rod of solid material) that Is machined
out to form
the shell shown in Figs. 1-3, Fig. 10 being a side view without cross-section,
and Fig. 11
being a longitudinal cross-section through the tip end portion to show the
internal multi-
diameter machined cavity, the tip being machined prior to drilling out a
remaining body
to the opposite end of the rod blank.
[0036] Fig. 12 is a side view of the shell in Fig. 10 on a channel-side
where the irrigation
tube channel is formed.
[0037] Fig. 13 is an enlarged view of the circled area labeled XIII in Fig.
12.
[0038] Fig. 14 is a cross section taken along line XIV-X1V in Fig. 13.
[0039] Fig. 15 is a perspective view of a welding fixture including weld
jaws for holding
the irrigation tube in place on the outer shell when welding the irrigation
tube to the
shell.
[0040] Figs. 16-17 are perspective exploded and perspective assembled views
of a gas
chamber for welding the shell and irrigation tube of Fig. 15 together; Fig. 16
showing a
general shape and position of the gas chamber relative to the jaws in the
fixture from Fig.
15.
[0041] Figs. 18-19 are exploded and assembled views of an ophthalmic
surgical
instrument (less electronics and utility wiring/tubing), the outer piece
including a shell
and weld-attached irrigation tube like that shown in Fig. 2, Fig. 19 also
showing the
system controls and fluid paths.
DETAJLED DESCRIPTION OF PIIFERRED EMBODIMENTS
(0042) As noted above, ophthalmic surgical instruments and systems are
generally
known by persons skilled in the art; therefore, a detailed description of
their function,
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use during surgery, electronic internal components, external controls, and
general
system is not necessary for an understanding of the present invention.
Accordingly, the
present disclosure focuses on the present pre-clocked innovative assembly of
an internal
subassembly (with tip, horn, multi-diameter shaft, and plug) mated with an
external
subassembly (with tubular shell and irrigation tube), Including features
causing accurate
clocking upon assembly, secure mating and defect-free welding interconnection,
and
including weld-facilitating features, fixturing and welding processes
associated therewith.
[0043] More specifically, an ophthalmic surgical instrument is provided
that includes a
tubular shell with external channel and mating irrigation tube attached along
a side of
the shell. Notably, the present tubular shell is made from a one-piece
continuous and
contiguous titanium metal rod blank machined at its tip end portion to include
a multi-
diameter cavity for supporting a sonically-vibratable tip. A remainder of the
rod is not
Initially machined, which eliminates problems of alignment and dimensional
distortion
caused by weld-related secondary operations. The present innovation eliminates
the
need to perfectly align and then weld a machined tip to an end of a thin-
walled tubular
shell, thus avoiding considerable process control and quality issues. After
the tip end
portion is machined and formed (externally and internally), a thru-bore is
drilled through
a remainder of the rod blank to form the remaining portion of the rod blank
into a thin-
wailed outer shell useful for operatively holding an internal assembly (i.e.
the internal
subassembly including the tip, horn, multi-diameter shaft, and plug, described
below).
[0044] The present apparatus 20 (also called "an ophthalmic surgical
instrument") (Figs.
1-3) includes a first (outer) subassembly Including a tubular shell 21 with
channel 22 and
mating irrigation tube 23. The channel 22 is formed in an outer surface of the
shell 21,
and extends from an angled radial hole 24 near a tip end 25 of the tubular
shell 21 to a
tail end 26. The irrigation tube 23 fits matably in the channel 22, and
includes a bent
forward end 27 that fits into the hole 24, and includes a rear end adapter 28
on the tube
23 extending past an open notch 40 in the tail end of the channel 22 formed by
an
annular flange 30 of the tubular shell 21. The combination of the tubular
shell 21 and
irrigation tube 23 form a handle that can be easily and comfortably grasped by
a surgeon,
with the surgeon easily recognizing the orientation of the handle by feel due
to the
clocked (rotational position) of the tube 23 and shell 21 to the tip 35.
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[0045] The present apparatus 20 (Figs. 2, 4,4A) includes a second
(internal) subassembly
including a tip 35, a horn 36, a shaft 37, and a plug 38, It is noted that
various tips are
commercially available and can be used with the present innovation. The
illustrated tip
35 includes an enlarged slightly-curved and/or beveled sharp tip end 35' on
its outer end
for cutting (during a surgical procedure), and includes threads on its inner
end for
threaded secure connection to the tip end portion of the horn 36. The horn 36
is
designed to sonically vibrate and precisely move the tip end 35' on the end of
the tip 35
for optimal cutting and surgical application. The multi-diameter shaft 37
(also sometimes
called a "bolt") is threaded into a tail end of the horn. 36. The plug 38 is
rotatably
positioned on the shaft 37 and includes an outwardly-extending annular flange
with a
notch 40' along its perimeter. The notch 40' is designed to receive and
matingly engage
the adapter 28 of the irrigation tube 23 (on the first outer subassembly) when
the second
internal subassembly is assembled into the first outer subassembly, as
described below.
Also, the plug 38 has a notch 40' that aligns with and generally matches notch
40'.
[0046] Fig. 5 shows threaded assembly of the shaft 37 to the horn 36, and
illustrates that
the horn 36 is clamped and held by a collet 50 with jaws 51 while the shaft 37
is screwed
into the horn 36 and then tightened to the specified torque using a torque
wrench 52
and torque wrench adapter 53 (the adapter 53 protecting the hex on the shaft
37). The
tip 35 is screwed Into the end of the horn 36 with a predetermined torsional
pretension
to prevent accidental release when being vibrated during use. At this point,
the horn 36
and the shaft 37 are interlocked by a strong threaded union. The tip 35 is
similarly
threaded into a tip end of the horn 36 with a threaded connection, including a
significant
torsional pretension as required by the design.
[00471 A fixture 45 (Figs, 6-7) includes a body 46 that holds the second
(internal)
subassembly in a particular known rotational orientation relative to the plug
38 while the
plug 38 is welded in position on the shaft 37. The fixture 45 includes an
adapter-
simulating feature 47 (i.e. similar in external shape to the adapter 28 on the
irrigation
tube 23) that keeps the plug 38 in proper clocked orientation during the
welding process
by engaging notches 40 and 40' (Figs, 3 and 4A). Notably, the illustrated weld
can be
done without addition of separate welding material, as described below.
Restated, the
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present Innovative process does not require the use a welding wire or external
welding
material.
[0048] Fig. 6 shows the first (internal) subassembly (i.e. a
threadably-engaged
preassembled tip 35 and horn 36 and shaft 37 from Fig. 5) positioned in the
fixture 45.
The plug 38 is slipped onto the shaft 37 and rotatably supported on the shaft
37 of the
first subassembly by the weld orientation fixture 45. The welding fixture 45
includes an
end piece 56 with a fixture orientation pin (not specifically shown) at
location 56' that
engages a side edges (or flat side) of the tip end 35' on the tip 35 to orient
the first
subassembly in a specific clocked (rotational) position. As illustrated, the
protruding
feature 47 also engages the notch 40' in the plug 38, thus orienting the notch
40' relative
to an orientation of the tip end 35' (i.e. "clocking" the tip 35 to the plug
38, such as to a
predetermined angular specification such as at 180 degrees, such as with +/- 5
degrees
tolerance, or potentially a tighter tolerance such as 2% degrees). The plug 38
is then
welded to the shaft 37, fixing its rotational orientation. Notably, as long as
replacement
tips 35 are purchased from the same supplier, our testing shows that the
threaded end of
the common-supplier tips 35 Is consistent enough to provide good and accurate
clocking
when an original tip 35 is replaced with a replacement tip 35, such as within
+/- 5
degrees, or even within +/- 2-1/2 degrees. However, the threaded connection
between
the horn 36 and shaft 37 is less consistent, and further there is a tapered
interfacing
surface that further renders the connection to have an inconsistent clocked
position
upon connection. The present innovation solves that problem.
[0049] Fig. 7 Illustrates an additional component of the fixture
45, which includes a
collet/clamp 60 with jaws 61 for gripping the plug 38 and for holding the
specific angular
clocked position relative to a direction of the tip end 35'. It is
contemplated that the
collet/clamp 60 could also be constructed to rotate the plug 38 to a desired
orientation.
The fixture 45/60 then holds the plug 38 for initial welding at location 64.
[0050) Fig. 8 Illustrates the first (internal) subassembly as
welded and interconnected,
including the tip 35 fixedly threaded to the horn 36, the horn 36 fixedly
threaded to the
shaft 37, and the plug 38 fixedly welded to the shaft 37, all with an angular
direction of
the tip end 35' and of the notch 40' being within a angular tolerance such as
180 degrees,
+/- 5 degrees (or a narrower range such as +1- " degrees).
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[0051] The controls for the welding operation may be varied as needed for a
particular
welding operation. It is contemplated that the weld can be done with or
without welding
wire, In the present innovation, the following parameters were used in welding
the
illustrated prototype with no weld wire and no added weld material being used.
Notably,
a skilled artisan will recognize that the laser power and parameters can be
adjusted
during the welding process for optimal results for a particular application;
[0052] EXAMPLE: Resonator set-up: Beam expander - 2.0, front mirror ¨ 150
mm,
aperture - 5.8 mm to 4.0, rear mirror ¨ 150 mm, and rear mirror type flat;
Laser Work
Parameter Setting: pulseform ¨ N/A, frequency 15Hz to 40Hz, pulse duration ¨
4.0 ms to
0.5 ms, volts ¨241 v to 257 v, energy ¨ 3.0 is min to 0.1 is min, E-control¨
off, beam
expander ¨ 216, burst number N/A, ramp number 10, ramp power N/A, ramp pulse ¨
0.1 ms, gas advance ¨ 0.1, delay ¨0.1, 2-cavities ¨ slm; and Peripherals:
nozzle ¨graphite,
nozzle length ¨ 0.600" to 0.500", assit gas type ¨argon, assit gas flow ¨ 10
cfh, final focus
setting 1.0 mm to 4.0 mm, Z height ¨ 1.028" to 1.150", and work coordinate ¨
G54.
[0053] As noted above, the present innovation also includes making the
entire shell 21
out of a one-piece titanium-metal rod blank. This is done to eliminate several
problems.
For example, the present Innovation avoids alignment and welding problems
associated
with welding a machined tip onto the thin-walled extruded tubular shell (e.g.
problems
Including mechanical alignment, distortion from non-uniform heat of welding
and later
cooling, and deformation that occurs in secondary operations necessary to
attach a
machined tip to a front end of a hollow tubular shell). The method of
manufacturing the
ophthalmic surgical instrument 20 comprises steps of providing a unitary one-
piece solid
rod blank (also called a "rod" herein) (Figs. 10-14) made of continuous and
contiguous
(non-welded) titanium material and that includes a unitary non-tubular body 51
and a tip
end portion 52 (which later becomes tip end portion 25) and a tail end portion
53 (which
later becomes tail end portion 26). The tip end portion 53 is machined to
define a multi-
diameter internal cavity 33, but the body 51 and the tail end portion 53 are
temporarily
left as a non-tubular solid mass of titanium material. The method includes
forming (e.g.
machining and/or forming) an outer surface of the tip end portion 52 to form a
configured taper from a diameter of the body 51 to a narrowed tip dimension
and so that
the tip end portion 52 is adapted to operably support a sonically-vibrating
beveled tip 34
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with beveled end surface extending longitudinally from the tip end portion 52.
Also,
shape and surface texture of the taper in tip end portion 52 and body 51
includes
grooves that provide a finger grip for a surgeon's fingers. The method
includes forming
the tail end portion 53 to form a flared taper extending from the diameter of
the body 51
to an increased tail dimension. Also, the method includes machining the tip
end portion
52 to include the multi-diameter-defining internal cavity 33 comprising a
first section
defining an end-adjacent first diameter 01, a second section defining a second
diameter
D2 adjacent the first section, and a third section defining a third diameter
03 adjacent
the second section, with the second diameter D2 being larger than the first
and third
diameters D1 and 03. The tip end portion 52 is constructed and adapted to
clearly
receive and support the sonically-vibratabie tip 34.
[00541 The non-tubular body Si. and tail end portion 53 are believed to be
novel and =
unobvious since they are initially a non-tubular solid mass of material. By
being a solid
mass, they can be welded on more easily without dimensional distortion. Also,
they are
constructed to be accurately machined later in the manufacturing process to
form a very
accurate and centered longitudinal bore (i.e. very accurate thin wall
thickness, such as a
thickness of less than 1 mm in some places) through the length of the shell
21. The solid
mass also allows the part to be welded on while maintaining a very accurate
dimensional
shape. Notably, after a welding operation, the shell 211s annealed to improve
dimensional stability and accuracy during later secondary processing.
[0055) As noted above, the channel 22 Is formed in an outer surface of the
shell 21, and
extends from a hole 24 near a tip end portion 25 and to a tail end portion 26
(Fig. 1). The
irrigation tube 23 (Fig. 2) is pre-formed to fit matably in the channel 22,
with its bent
forward end 27 (Fig. 1) fitting into the hole 24, and with a rear end adapter
28 (Fig. 2) on
the tube 23 extending past an open notch 40 of the channel 22 formed by an
annular
flange 30 of the tubular shell 21. The channel 22 has an embossed narrowed
region 32
(Figs. 12-14) with protruding ridge 32A. The ridge 32A is configured to abut
the tube 23
when first fixtured together. The embossed area around the narrowed region 32
is
shaped somewhat like a butterfly and, when formed, causes the ridge 32A to
slightly rise
above the channel 22. As will be recognized by a skilled artisan in welding,
this ridge 32A
facilitates initiation of a laser welding process by providing good abutting
contact
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between the tubular shell 21 and irrigation tube 23 at ridge 32A, both in
terms of
providing access and also providing point-focused heating, such as for a laser
beam
welding operation. Specifically, it facilitates heating and flowing of the
material from the
tubular shell 21 Into welded bonding contact with the irrigation tube 23 with
minimized
physical and aesthetic defects and imperfections, yet without the need for
addition of
separate welding material. Notably, the embossment feature (i.e. ridge 32A) is
consumed
and unidentifiable after welding.
(0056) The method of manufacturing the ophthalmic surgical instrument 20
comprises
steps of matably engaging the irrigation tube 21 with the channel 23 (Fig. 2)
with a bent
forward end 27 (Fig. 1) of the tube 23 positioned in the hole 24 and a rear
end adapter 28
(Fig. 2) of the tube 23 extending to the tail end portion 26 (Fig. 1). The
method further
includes laser beam welding the tubular shell 21 to the irrigation tube 23 on
both sides of
the channel 22 with the welding extending a length of the channel 22, the weld
material
being from the tubular shell 21 and/or the irrigation tube 23. Notably, the
illustrated step
of welding does not use separately added welding material, such as welding
wire.
Notably, even though the present innovation uses zero external weld material
and laser
welding, it is contemplated that a scope of the present innovation includes
supplying
added welding material and/or using a different welding process.
[0057] Notably, the irrigation tube must be fully "sealed" after welding.
In other words,
when fluid in the irrigation tube fills up the nosecone portion of the shell,
no fluid can
leak back to the outside of the hand piece. The illustrated "butterfly wing"
design is
believed to greatly assist in creating a tight and good seal during the
welding process.
This is believed to be in part because the thinning at a specific point allows
the
manufacturer to use the laser and fIxturing to "pinch" the material together,
resulting in
an improved and better and more consistent seal.
[0058] Welding titanium material is difficult, and requires that the area
to be welded be
oxygen-free during the welding operation. The fixture 50 (Fig. 15) and gas
chamber 51
(Figs. 16-17) are designed to facilitate the present welding operation,
including making
the operation more efficient while using less wasted oxygen-eliminating gas
during the
welding operation. The fixture 50 (Fig. 15) Includes multiple L-shaped weld
jaws 52-54
(three being illustrated). One jaw 52 is designed to abut the tube 23 and hold
the
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,
irrigation tube 23 in the channel 22 (Fig. 9) and against the shell 21. The
other two jaws
53-54 are radially spaced to oppose the jaw 52 and securely hold the assembly
(including
the shell 21) during the welding process. The L-shaped Jaws 52-54 each include
a shell-
engaging longitudinally-protruding arm 55 for engaging the shell 21/tube 23,
and Include
a radially-extending base-supported arm 56 adjustably supported to move the
shell-
engaging arm 55 into and out of fIxturing clamped engagement with the shell 21
and
tube 23.
[0059] The gas chamber 51 (Fig. 16) includes a main body 61, an aperture
end cap 62 (for
receiving the shell-engaging arms 55 of the jaws 52-54), a closed end cap 63,
and a cover
slide 64. The main body 61 includes an open side covered by the cover slide
64, and the
cover slide 64 Is slIdably mounted in track grooves 65 along the open side of
the main
body 61. A window 66 in the cover slide 64 provides access for a laser beam
for the
welding operation.
[0060] The controls for the welding operation may be varied as needed for
a particular
welding operation. For example, the following steps and parameters were used
in
welding the present prototype, such as is illustrated in Fig. 1.
[0061] Three titanium subcomponents (Figs. 15-17) are initially assembled
and then
welded, the subcomponents including: 1) the one-piece shell outer 21, 2) the
irrigation
tube 23, 3) the rear end adapter 28 (also called "female luer adapter")
fitting on end of
irrigation tube 23. Notably, the adapter 28 can be welded to the tube 23 ahead
of
welding the tube 23 to the shell outer 21 if desired. The welding creates a
continuous
leak-proof joint entirely around and along the tube 23 and shell 21 that is
aesthetically
appealing, and that is structurally robust to withstand the rigors of many
cycles of
surgery, cleaning, and rough handling. Notably, the Illustrated welding
process did not
utilize a weld wire filler to overcome poor fit-up or joint design.
[0062] The illustrated welding process is somewhat complex and has many
interrelated
components to facilitate a high-quality, excellent-appearance weld. However,
generally
stated:
a. The actual weld parameters are controlled within the part run program. The
program has several parameter changes to address specific challenges in
target areas on the part. The "recipes" within the program include changes in
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Feed rates, Pulse Frequency (Hz), Energy (Joules), Pulse Duration (ms), and
Energy Ramping (upslope/downslope). The energy levels vary from 2,5Js for
the "Butterfly seal" to .95 is in the delicate nosecone area. A person of
ordinary skill in welding of titanium and in laser welding would know how to
optimize those parameters, such that a detailed discussion of the parameters
is not required In this disclosure.
b. Presenting the assembled part for weld is done utilizing a high
performance,
high precision three-jaw chuck with specially designed jaws (Fig. 15) and gas
chamber (Figs. 16-17) that allow a proper angle of presentation of the laser
beam to the part for a completed one operation weld. This jaw-fixture and
gas chamber allows for angle of approach to exceed 65 degrees.
c. Removing oxygen from the welding environment is critical for successful
titanium welding, because Oxygen absorbed into the weld creates structural
defects, reduces strength, and creates visual imperfections. The illustrated
"Gas Chamber" (see Figs. 16-17) enhances the introduction of shielding gas to
the weld zone while purging the oxygen from the work envelope surrounding
the part, yet does so in a manner minimizing the amount of purging gas
required. The illustrated arrangement of Figs. 16-17 is sometimes referred to
as a "glove box" welding system, and is part-specific and is generally
designed
to reduce the costs of wasted gas while improving processing throughput.
d. Post processing of weld is an important component of the processing. While
heat treating of titanium is generally known, we have incorporated a stress
relieving process with goo temperature/time control in order to maintain the
tolerances required for subsequent processing and ultimately the finished
product. The present process is believed to be new and unobvious, since it is
not presently specified in known processes for forming parts similar to the
present tubular shells 21, yet it yields a superior finished product, which is
contrary to conventional thinking when using welding, particularly when
welding without adding additional welding material such as from a welding
wire.
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[0063] To assemble the apparatus 20 (Fig. 15), Fig. 18 illustrates the
internal
subassembly (i.e. the tip 35, horn 36, shaft 37, and plug 33 and including
electrical wires
. operably connected to the horn 36) are positioned inside the external
subassembly (i.e.
the fully-formed outer shell 21 with irrigation tube 23 and adapter 28), and
then friction-
fit the tail end cap 39A (Fig. 18) on a tail end of the outer shell 21 (with
the wires
extending through the wiring port in the end cap 39A), thus holding the
assembly
together. Thereafter, as shown in Fig. 19, the adapter 28 is connected to the
irrigation
source/path (i.e. fluid going into the eye to equalize pressure), the tail of
the Interior
subassembly (i.e. the tail of the multi-diameter shaft 37, which protrudes
through the
end cap 39A) is connected to the aspiration/fluid-debris-removal path (I.e.
fluid leaving
the eye that is sucked out along with organic material such as a lens and
cataract), and
electronic/sonic/handset wiring/tubing controls are connected the equipment
system
control (electronics and utilities) (or otherwise connected as required by the
equipment
system manufacturer).
[0064] It is to be understood that variations and modifications can be made
on the
aforementioned structure without departing from the concepts of the present
invention,
and further It Is to be understood that such concepts are intended to be
covered by the
following claims unless these claims by their language expressly state
otherwise.
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