Note: Descriptions are shown in the official language in which they were submitted.
33~
This invention relates to machine tools.
More particularly, ~he instant invention concerns
accessories and attachments for machine tools.
In a further aspect, the present invention concerns
a fixture or holding a work piece during machining oper-
ations.
Various methods are well known for fabricating an
article from raw material. Broadly, commercial and
industrial fabricating processes can be classifiecl under
the headings of machining, forming and assembling. Of
immediate concern, is the procedure of machining
In general, machining can be defined as the act of
or the processes involved in shaping a solid piece of raw
material into a finished product, usually in accordance
with a predetermined plan as may be given by a blueprint.
I`he material being worked upon is usually referred to as
the work piece. During machining, various cutting opera-
tions are performed upon the work piece by a machine tool.
Common machining operations include drilling, turning,
boring, grinding, shaping, planing and other well known
material removing procedures. The actual removal of
material is done by a cutting tool which is held and
driven by a machine tool, such as a drill press~ lathe,
ver~ical and horizontal milling machines, surface grinder,
internal and external grinders, shaper and planer. Other
machine tools and cutting processes will readily occur to
those skilled in the art.
~i`37~6
The prior art is replete with clamping and holding
devices for supporting a work piece during machining.
Face plates, chucks and cullets are used to hold the work
~iece for lathes and other machine tools in which the work
piece is rotated against a stationary cutting tool. Angle
plates, vises and various hold-down and clamping arrange-
ments are commonly used to secure work in machine ~ools of
the types having a rotating cutter, Milling machines and
similar machining tools have integral work supporting
tables, while in machines of the type represented by lathes,
the work supporting device is attached to a spindle.
Each type of work supporting fixture has unique,
inherent characteristics which are especially sui~ed for
particular machining operations. Vises and chucks grip a
portion of the work piece which is then unavailable for
machining. Face plates and angle plates can be made to
support work in such a manner that substantial portions
of the work piece are exposed. Numerous means are commonly
employed within the art for securing the work piece to a
plate-type holding fixture. For example, clamps may
embrace the work piece and in turn be secured to the plate
by bolts received directly in tapped holes within the
plate, or engaged with T-nuts carried in especially
machined slots which extend along the surface of the plate.
Another arrangement includes the use of C-clamps or
parallel clamps straddling both the work piece and the
plate for abutting the work piece against the surface of
the plateO
- 2 -
i~37~d6
For production machining it is common practice to
provide a face plate having a plurality of apertures,
either slots or cylindrical bores t extending therethrough.
The work piece~ usually a rough cast or molded item, is
preliminarily prepared by machining a flat surface which
then becomes the base or reference surfclce. Threaded
holes, normally made by drilling and tapping, are formed
into the work piece from the machined surface. To provide
adquate support, two or more threaded holes may be created.
The machined surface of the work piece is then placed
against the work supporting surface of the plate. Sub-
sequently, bolts are passed through the apertures in the
plate and threadedly engaged within the preformed holes
in the work piece. Locating fixtures of various types
are commonly used to maintain relative positioning between
subsequent work pieces to enable machining operations to
be accomplished without resetting the machine.
The latter method of attaching a work piece to a
face plate has obvious advantages over clamping type methods.
A substantially greater portion of the work piece is avail-
able for machining. However, it is physically impossible
to provide a plate having an infinite array of apertures.
Therefore, the holes drilled and tapped into the work piece
must be accurately located to align with pre-existing
apertures within the plate or apertures especially created
for the immediate purpose When considering a large pro-
duction run, the accurate location of several threaded
holes within the work piece is a slow laborious task
presenting undue financial burden upon the manufacturer.
~L~g;93~
Ihis is especially true when considered that the threaded
holes function only as an intermediate expediency and are
of no final value. The foregoing burden is also applicable
to the machinist, who is concerned with only a single work
piece.
The fixture alone may, however, provide only a
partial solution to the shortcomings of the prior art and
may be inadequate in use with certain machine tools and
under certain machining operations. Sufficient clearance
must be provided on the backside of the face plate for
manipulation of the bolt which extends through the fixture
into the work piece. The space requirement is generally of
minor concern when the fixture is positioned perpendicularly
to the work support surface of the machine tool. When posi-
tioned parallel to the work supporting surface, as is fre-
quently required during machine tool practice, the fixture
must be elevated. This represents a serious limitation.
For example~ machine tools have a characteristic maximum
distance between the cutting tool and the work support
surface. Height which is occupied by the work holding
fixture subtracts from the working height of the machine
and places a dimensional limit upon the work piece. The
fixture is inoperative in combination with machine tools
of limited capacity. Also, the ability of a machine tool
to remove stock at a rapid rate is limited9 at least
partially, by the rigidity of the work piece. As a geneTal
rule, rigidity is decreased in proportion to the distance
of the work piece from the normal work support surface of
the machine tool. Further, it is an annoyance and a
hindrance for the machinist to perform simultaneous
- 4
~t3~
manipulative functions on either side of the work holding
fixture. Accorclingly, an alternate embodiment is also
here described.
It would be highly advantageous,therefore, to
provide improved work holding means.
Accordinglys it is an object of the instant inven-
tion to provide a fixture for holding a work piece.
Another object of the invention is the provision
of a fixture adapted for use with a machine tool to
support a work piece during machining operations.
And, another object of the current invention is to
provide a fixture of the plate type having various optional
means for securing a work piece thereto~
Still another object of the invention is the pro-
vision of a work piece holding -fixture which is usable with
a variety of machine tools.
Yet another object of the present invention is to
provide a holding fixture which is opera~ively usable with
a work piece having preformed securement means.
A further object of the invention is the provision
of a fixture which is self-aligning ~o compensate for
inaccuracies of the securement means of the work piece.
Still a further object of this invention is to
provide a work piece holding device which is usable in
prototype and production machining situations.
~3~
And yet a further object of the invention is the
provision of a fixture of the above type which is readily
usable and durably constructed.
Yet another object of this invention is to provide
a fixture which occupies a minimal portion of the working
distance of the machine tool.
A further object of the invention is to provide a
fixture which is operative at pre-selected angular arrange-
ments relative the work support surface of a machine tool.
And a further object of the invention is the pro-
vision of a work holding fixture which can be placed in
juxtaposition with the work support surface of a machine
tool.-
Yet a further object of the instant invention is to
provide a fixture which is operative from a single position. ;
And yet a further object of the invention is theprovision of a fixture which will rigidly support a work
piece in close proximity to the work support surface of a
machine tool.
Still a further object of the invention is to provide
a fixture which will readily and conveniently accept pre-
prepared work pieces.
Yet still a further objec~ of the invention is the
provision of a fixture of the above type which will inter-
changeably accept work pieces of varying dimensions.
- 6 -
7~
Thus, in accordance with the present teachings, a
fixture is provided for use with a machine tool and for
holding a workpiece during machining operation by the machine
tool. The fixture comprises a substantially rigid plate which
has a first work supporting surface and a second spaced
opposed surface with a generally cylindrical bore extending
through the plate between the first work supporting surface
and the second surface thereof. A spindle is provided which
has first and second ends and an outer generally cylinclrical
surface and which is journalled within the bore for rotation
about the longitudinal axis of the bore with the first end
~f the spindle beiny positioned proximate bu~ slightly
recessed from the first work supporting surface of the plate.
First retention means is provided for limiting the axial
movement of the spindle in a direction toward the first work
supporting surface of the plate and engagement receiving means
is provided carried by the spindle for receiving means for
securing the workpiece against the first work supporting surface
of the plate.
:~i
-6a-
~ 3t~ ~
Brieflyt ~o achieve the desired objectives of the
presen~ invention in accordance with a preferred embodi-
ment thereof, first provided is a subs~antially rigid
plate having first and second spaced opposecl surfaces.
The first surface is considered the work bearing surface.
Extending through the plate are a plurality of generally
cylindrical bores each having a longitudinal axis substan-
tially perpendicular to the work supporting face. A spindle
is rotatably journaled within each ~ore for rota~ion about
the longitudinal axis. Each spindle has a first end, which
is positioned proximate the first surface of the plate.
Retention means are provided :Eor limiting the actual
movement of the spindle in a direction toward the first
surface o-f the plate. Engagement receiving or attachment
means are carried by each spindle for receiving means for
securing the work piece against the work bearing surface
of the plate. Actuator means may be carried by the plate
for retracting the insert from the bearing s~rface and
drawing the work piece into contact with the bearing
surface.
In a further embodiment, the attachment means is
in the form of a pin which is detachably engaged with the
work piece. An aper~ure within the insert receives the
pin and connection means are provided for detachably
securing the pin ko the insert. The connection m~ans may
be in the form of a thrust member which engages a shoulder
of the pin and bears against an opposing shoulder of ~he
insert.
The ac~uator means, in a specific embodiment,
comprises a thrust ring which cammingly extends and retracts
~ ~ 3~
the insert along the axis thereof in response to rotation
of the ring. A passage is provided through the side of
the plate for a tool which detachably engages and rotates
the locking ring~ The thrust member of the connection means
is also receivable through the passage. A rotatable insert,
having a slotted aperture therethrough, provides for align-
men~ of the pin receiving aperture.
Preferred engagement means carried by each spindle
is in the form of a radial slot extending axially through
the spindle. A bolt is receivable through the slo~ for
engagement with a threaded hole preformed in the work piece
and for securing the work piece to the work supporting
surface of the plate. The relative position of the slot,
with reference to the surface of the plate, is moveable in
response to rotation of the spindle. The spindle may also
carry other engagement receiving means such as a T-slot
extending diametrically across the end of the spindle.
Preferably, the end of the spindle is recessed from the
work supporting surface of the plate to insure that the
work piece abuts the work supporting surface.
Alternate embodiments of the plate are adapted for
use with various machine tools. In accordance with the
foregoing embodiment, the plate is placed horizontally
upon the normal work supporting surface or table of a
machine tool. In an alternate embodiment, a second plate
resting upon the normal worX supporting surface of the
machine tool holds the work supporting surface in vertical
alignment.
In yet another embodiment J means are provided on
the second surface of the plate or detachable securement
to spindle type machines,
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~L~Q;;~7~1~
The foregoing and further and more specific objects
and advantages of the present invention will become readily
apparent to those skilled in the art from the following
detailed description of the invention and alternately
preferred embodiments thereof taken in conjunction with
the drawings in which:
Fig. 1 is a perspective view of a work piece holding
fixture constructed in accordance with the teachings of the
present invention as it would appear when placed upon the
normal work supporting table of a machine tool, such as a
milling machine;
Fig. 2 is a perspective view generally corresponding -~
to the view of Fig. 1 and further illustrating the-device
of the present invention having a work piece supported
thereby in position for machining; ~ -
. .
Fig. 3 is an offset vertical sectional view taken
along the line 3-3 of Fig. l;
Fig. 4 is an enlarged fragmentary view of the work
supporting surface of the device of Fig. l;
.~ .
Fig. 5 is an enlarged fragmentary perspective view
of the fixture of Fig. 1 and shown partly in section as
; generated along the line 5-5 of Fig. 4;
Fig. 6 is an alternate embodiment of a work holding
fixture constructed in accordance with the teachings of
; the present invention, and especially adapted for use with
spindle type machines, specifically herein shown as a lathe.
Fig. 7 is a perspective view o-f a work piece holding
fixture constructed in accordance with the teachings of the
instant invention as it would appear when secured to the
normal work support surface of a machine tool and holding a
work piece, the work piece being shown in broken outline;
Fig. 8 is an enlarged exploded partial perspective
view of the device of Fig. 7, components thereof being
broken for purposes of illustration;
Fig. 9a is an enlarged fragmentary vertical sectional
view taken along the line 9-9 of Fig. 7 and showing the
device thereof as it would appear in the work piece receiving
posltlon;
Fig. 9b is a view generally corresponding to the view
of Fig. 9a and showing the device thereof in the subsequent
work pieceholding position; and
Fig. 10 is a partial perspective view of the underside
of the fixture of Fig. 7.
Turning now to the drawings in which the same reference
numerals represent corresponding elements throughout the
several views, attention is first directed to rig. 1 which
shows a preferred embodiment of a fixture in accordance with
.
the instant invention and generally designated by the
re-ference character 10. Fixture 10, as is also seen in
Fig. 3, includes a substantially rigid plate 11 having
first and second spaced opposed surfaces 12 and 13. Plate
11 is generally rectangular having first and second longi~
tudinal edges 16 and 17 respectively and first and second
- 1 0 -
.
~33~
lateral edges 18 and 19 respectively. First surface 12
is considered the work supporting surface, as will be
described presently.
Rigid base plate 2Q having top surface 21 and
bottom surface 22 is secured to second surface 13 of
plate 11 such as by mechanical fasteners, welding or
other expediencies well known in the metal working art.
Bottom surface 22 of base plate 20 is perpendicular to
first surface 12 of plate 11.
Table 23 is representative of the typical work
supporting table common to various machine tools, such
as milling machines for example. Table 23 includes work
supporting surface 26 having a plurality of parallel
longitudinally extending T-slots 27. The use of T-slots
27 in conjunction with various clamping devices for
affixing a work piece directly to work supporting surface
26, or alternately for securing an auxiliary work holding -~
device, such as a vise or conventional angle plate, to
surace 26 will be readily understood by those skilled
in the art.
:~ :
Surface 26 is a precision surface which is flat and
generally either perpendicular or parallel to a cutting
tool 28 rotated and held by spindle 29 of the machine
tool as seen in Fig. 2. Bottom surface 22 rests upon
work supporting surface 26 and holds first surface 12 of
plate 11 in perpendicular alignment with surface 26.
Rigidity is provided by gusset 30 affixed to base 20 and
plate 11 proximate second lateral edge 19. Further rigidity
is providffd by end plate 31 similarly affixed to base 20 and
plate 11 proximate first lateral edge 1~. In accorclance
- 11 -
~ ~ ~ 3~7~ ~
with the immediate embodiment, end plate 31 has an outside
surface (not herein specifically illustrated) which is
perpendicular to first surface 12 and to bottom surface 22.
End plate 31 can be employed, similar ~o base plate 20 to
rest upon work supporting surface 26 and support first
surface 12 in a substantially vertical position. Various
means for rigidly at~aching base plate 20 or end plate 31
to table 23 will readily occur to those skilled in the art.
For this purpose and to accommodate bolts threadedly
engageable with T-nuts carried within T-slots 27, base
plate 20 and end plate 31 may have apertures, either in
the form of cylindrical bores or slots, formed therethrough.
It will also be appreciated by those skilled in the
art tha~, in accordance with alternate embodiment o-f the
instant invention, plate 11 is singularly usable without
base 20, gusset 30 and end plate 31. In this configuration,
plate 11 is placed horizontally and directly upon work
supporting surface 26. If it is desired to elevate plate
11 from work supporting surface 26, various types of well
known spacers, such as those commonly referred to as
parallels, can be placed between work supporting surface 26
and second surface 13 of pl~te 11. Plate 11 can be secured
:
to table 23 by clamps or other well known means usually em-
ploying the use of T-slots 27. Like it should be obvious
that in certain other embodiments such as shown in Fig. 7-10
the fixture 10 may include recesses 70 extending downward~y
from work bearing surface 12. Slots 51 extend inwardly
from end surfaces 18 and 19 between surfaces 13 and 12, and
base surface 13 rests upon work support surface 26. Conven-
tional T-nuts 72 reside in approprlate T-slots 27 in align-
- 12 -
~37~i
ment wlth slots 71. Cap screw 73 extend through slots 71
into respective T-nuts 72. Each cap screw 73 has a head
74 which is received in the appropriate recess 70 below
the level of work bearing surface 12 to provide an un-
obstructed surace.
A plurality of spindles 32 are carried by plate 11.
As clearly observed in Fig. 5, each spindle 32 has an
outer cylindrical surface 33 which is rotatably journaled
within a bore 34. Each bore 34 extends through plate 33
between irst surface 12 and second surface 13 and is
cylindrical about a longitudinal axis shown by the broken
line A, which is perpendicular to -face 12. Each spindle
32 is also rotatable about axis A. Each insert 32 has
attachment means 75 extending therefrom which engage a work
piece shown in broken outline 57. The action of the inserts
32, and the mechanism associated therewith, draws work
piece 57 tightly against work bearing surface 12. The
work holding function of the present invention will become
apparent as the description ensues.
Each bore 34 includes a counterbore 37 extending
inwardly from second surface 13 and terminating with annular
shoulder 38 extending radially between bore 34 and counter-
bore 37. Outer surface 33 of spindle 32 comprises a first
cylindrical section 39 and an enlarged second cylindrical
section 40 with annular shoulder 41 extending radially
therebetween. First cylindrical section 39 and second
cylindrical section 40 are rotatable within bore 34 and
counterbore 37 respectively. The contact beween annular
shoulder 38 and annular shoulder 41 provides retention means
for limiting an axial movement o-f spindle 32 in a direction
towards first surface 12, as indicated by arrow ~O Further-
- 13 -
more, as is illustrated in Fig. 9a first section 39 in
addition to being sized to be rotatably and slidably journaled
within bore 34, also incorporates an O-ring seal 76, residing
in annular groove 77 formed in first section 39 proximate
first end 42. This prevents the passage of machining fluids,
machining parti.cles and other contaminants from upper surface
12 of plate 11 to the actuating mechanism as will be described
presently.
Each spindle 32 has a first end 42 and a second end
43 each of which are generally perpendicular to axis A and
which are positioned proximate first surface 12 and second
surface 13 respectively of plate 12. Preferably~ end 42 is
recessed slightly, 5/1,000 of an inch for example, from
first surface 12, the purpose of which will be explained
presently An annular groove 44 is formed in plate 11
extending radially outward from counterbore 37. A lock
ring 47, an annular member which is split radially, resides
within groove 44. Lock ring 47 extends radially inward from
counterbore 37 to receive second end 43 thereagainst and
prevent the separation of spindle 32 from plate 11.
Referring now specifically to Figs.4 and 5, it is
seen that each spindle 32 is provided with various engage-
ment receiving means for securing a work piece against
surface 12 of plate 11. First engagement receiving means
is in the form of a slot 48. Slot 48 extends through
spindle 32, bei.ng open at first end 42 and second end 43.
Slot 48 also extends in a radial direction terminating at
shoulder 41 to be open with respect to first cylindrical
section 39 and closed with respect to second cylindrical
section 40. Preferablyl the inner end 49 of slot 48 is
- 14 -
3~
semi-cyli.ndrical about axis Ao Accordingly, means for
securing a work piece against first surface 12 can be
received through slo~ 48 at the center of spindle 32.
I~ the securing means is a bolt, for example, the longi-
tudinal axis of the bolt can align with axis A. The
relative position of the bolt with respect to work sup-
porting surface 12 is readily alterable and determined
by the axial placement of the bolt along slot 48 and the
rotation of spindle 32. It will be appreciated, therefore,
that the bolt is capable of assuming any position within
bore 34.
Second engagement receiving means carried by spindle
32 is in the form of a T-slot 50. T-slot 50 extends dia~
metrically across spindle 32 and is open at first end 42.
Access to T-slot 50, for the insertion of a T-nut or
T-headed bolt therein, is provided by an opening 51 having
substantially the same width as the enlarged portion of the :
T-slot and positioned at approximate the axial center of
spindle 32. It will be readily recognized by those skilled
in the art that T-slot 50, similar to slot 48, is movable to
provide engagement receiving means over the entire area
defined by bore 34 in accordance with rotation of spindle
32. A plurality of spaced threaded holes, such as formed
by the operations of drilling and tapping, are also carried
by spindle 32 and form third engagement receiving means.
Each threaded hole 52 extends substantially perpendicu-
larly inward from first end 42.
Eixture 10 further includes fourth engagement
receiving mean.s which are carried by a plate 11. Fourth
engagement receiving means comprises longitudinal T-slots
3t~ ~
53 and lateral T-slots54. T-slo~s 53 and 54 are acces-
sible from first surEace 12 and are arranged to lie
between spindles 32.
A typical work piece, such as work piece 57 shown
in Fig. 2, can be readily attached to ixture 10 by various
means consistent with the immediate desires of the machine
tool operator. As previously stated, it is conventional
practice to prepare the work piece by machining a base
surface and forming two or more threaded holes. With
conventional angle plates or work holding fixtures, it
was required that the ~hreaded holes be accurately placed
to align with pre-existing bolt receiving holes within
the angle plate. Alternately, the angle plate could be
drilled to accommodate a given work piece and threaded
hold placement. It was also necessary that several fixtures s
be available for use in accordance with the particular size
and threaded hole placement of numerous and various work
pieces 9 since it is obvious that a limited number of
holes can be drilled through a given fixture.
':
With the fixture o:E the instant in~ention, accurate
placement o the threaded holes in the base of the work
piece is rendered unnecessary. The appropriate spindles
are simply rotated until the slots 48 align with respective
holes. This is particularly important in the production
run machining operations where locating means are used in
combination with the holding fixture of the instant inven-
tion. The locating means places each successive work piece
at approximately the same location on face 12. Ro~ation o
the appropriate spindles readily compensates for inaccuracies
3~
in the placement of threaded holes of subsequent work pieces.
Other obvious advantages are also accrued from the
work holding fixture of the instan~ invention. The use of
various straps and clamps in combinatic~n with T-slots or
threaded holes is conventional prac~ice and well known to
those skilled in the art. Heretofore, the placement of
the clamps or straps upon the work piece has been restricted
in accordance with the availability of T-slots or threaded
apertures in a given work holding fixture. Frequently, it
was necessary to clamp the work piece at available locations
and machine that portion of the piece that was exposed for
màchining. Subsequently, the work piece was reoriented and r
reclamped to make the remaining portions of the work piece
to the cutter of the machine tool. With the device of the
instant invention9 it is readily apparent that an infinite
number of clamping positions are available between the
combination of the T-slo~ 53 and 54 carried by plate 11,
and the T-slots 50 and threaded holes 52 which are removable
in accordance with the rotating spindle 32.
As the bolt or other securing means is tightened,
shoulder 38 is drawn firmly against shoulder 41 and the
base of the work piece is drawn firmly against work holding
surface 12~ This is assured since first end 42 of each
spindle 32 is recessed from surface 12. During the secure-
ment of the work piece to face 12~ no stress is applied to
locking ring 43.
Fig. 6 illustrates an alternate embodiment of a work
holding fixture constructed in accordance wit~ the teachings
- 17 -
37~
of the instant invention and generally designated by the
reference character 60. Embodiment 60 is particularly
adapted for use in combînation with the type of machine
tool which rotates the work piece such ;as typically
illustrated by lathe 61. Briefly, lathe 61 includes bed
62 and head stock 63 which drivingly rotates spindle 64.
Further description of lathe 61 will not be made, since
such machine tools are well known to those skilled in the
art.
Work holding fixture 60 includes a generally
cylindrical rigid plate 67 having a work bearing first
surface 68 and a spaced opposed second surface 69 J the
latter not being specifically visible. Plate 67 is
generally analogous to plate 11 except for the parametric
shape thereof. A plurality of spindles 32, as described
in connection with the previous embodiment, are rotata6~y
carried by plate 69. In the immediate embodiment, spindles
32 are placed annularly about work supporting face 68.
, . .
Although not specifically herein illustrated, but
as will be readily understood by those skilled in the art,
attachment means extend axially from second surface 69 for
coupling fixture 60 with spindle 64. Manufacturers of
lathes and other rotating type machine tools generally
provide a variety of various work holding devices, such
as face plates, chucks and cUllets, which are detachably
securable to the spindle of the machine in accordance with
the immediate needs of the machine operator. The exact
means of attaching the work holding device to the spindle
is variable with the specific manufacturer, but generally
includes some type of threaded connecti-on or pin and cam
- 18 -
.. ..
:, ' ,' !
~ ~ 3~ ~ ~
lock arrangement. The attachment means, as an independent
accessory item, is oftén supplied by the manufacturer for
use by machine tool operators desirous o-f fabricating a
specialized work holding fixture. Such an accessory is
readily securable to plate 67. Alternately, plate 67 can
be secured directly to a face plate as supplied by the
manufacturer.
As illustrated herein, work piece 57 is being ~ ;
attached to fixture 60 for turning, boring and facing
operations as are usually performed on lathes. Work piece
57 has been prepared by machining the base surface, if
necessary, and forming threaded holes therein as appro-
priate. Subsequently, the base surface of work piece S7
is placed against work holding surface 68 of plate 67.
Finally, bolts 71 are received through slo~s 48 and
secured with the threaded holes in work piece 57. A
cente~ or other locating device may be used for placement
of worX piece 57 and the appropriate spindles 32 rotated
to bring the respective slots 48 into alignment with the
threaded holes in the work piece.
The actuator means best seen in the Figs. 7~10
embodiment includes thrust ring 78 and locking ring 79,
which reside in counterbore 37. Thrust ring 78 is an
annular member having outer surface 80, inner surface 81,
first end 82 and second end 83. Counterbore 84 extends
inwardly from second end 83 and terminates with annular
shoulder 85 extending to inner surface 81. Insert 32 and
thrust ring 78 are interlocked for relative movement in one
direction by the abutment of shoulder 86 against shoulder
85. Accordingly, as thrust ring 78 moves in a direction
- 19 -
away from work support surface 12, .insert 32 is forced in
the same direction, Guide pin 86~ press fitted into
aperture 87, extends from first end 82 of locking ring
79 substantially parallel to axis A. The projecting
portion of guide pin 86 is slidably received in guide
socket 88. Pin 86 and socket 88 comprise stabilizi.ng
means for preventing rotation of thrust ring 78 relative
plate 11.
~'
Annular locking ring 79 includes outer cylindrical
surface 89, inner cylindrical surface 90 and first and
second ends 91 and 92, respectively. Outer cylindrical ~`
surface 89 is rotatably journaled within counterbore 37.
First end 91 is a thrust surface which bears against
annular shoulder 38. Split ring 47, carried in annular
groove 44, extending radially outward from counterbore 37,
receives second end 92 of locking ring 79 thereagainst `:
and provides retention means for retaining locking ring
79 within collnterbore 37. Thrust ring 78 and locking ring
79 therefore, in this embodiment, act as an extension of
second cylindrical section 40 of spindle 32 and simply
are an exaggeration thereof.
Thrust ring 78 and locking ring 79 have a camming
relationship such that longitudinal movement along axis A
is imparted to thrust ring 78 in response to rotation of
locking ring 79. The camming relationship may be affected
by various camming means carried by thrust ring 78 and
complemental cam means carried by locking ring 79. In the
immediate embodiment, the cam means comprises an external
screw flight 95 carried by outer surface 80 of thrus~ ring
78, and a matingly engagable internal screw flight 96
carried by inner surface 90 of locking ring 79.
- 20 -
A plurality of angularly spaced bores 97 extend
radially inward from outer surface 89 of locking ring 79.
Elongate tool element 98, having engaging end 99 and hand
grip end 100, .is used for rotating locki.ng ring 79O The
several bores 97 function as sockets for sequentially
receiving engaging end 99. Tool element 9g is received
through passage lOi which is o-f sufficien.t width to expose
at least two bores 97.
An annular groove 101 is carried in couterbore
84 of thrust ring 78. Bore 102, extending radially inward
from second section 40 of insert 32, is aligned with annular
groove 101, Threaded aperture 103 extends inwardly from
second end 43 of insert 32 and intercepts radial bore 102.
Balls 104 are carried in bore 102 and the movement of the
balls 104 within bore 102 is controlled by grub screw 105
threadedly engaged within aperture 103. As specifically
illustrated in Fig. 9a, grub screw 105 is in the advanced ~ .
position, abutting the inner ball 104 and urging the outer
ball 104 into annular groove 101. It is noted that outer
ball 104 resides partially within annular groove 101 and
partially within bore 102. Groove 101 provides a race for
outer ball 104 during rotary motion of inser~ 32 relative
thrust ring 78. The foregoing arrangement functions as a
detent Eor preventing axial movement of insert 32 relative
thrust ring 78. Upon retraction of grub screw 105, both
balls 104 are free to move completely within bore 102,
whereby insert 32 is removable from thrust ring 78 in a
direction away from work bearing surEace 12 of plate 11.
Attachmen~ means 75 includes pin 106, having first
and second ends 107 and 108, respectively, which is
re-ceived through aperture 48. First end 107 of pin 1()6
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37~
extends beyond first end 42 of insert 32 and second end
108 of pin 106 projects beyond the second end 43 of insert 32.
Pin 106 is movable within elongated aperture 4~ between an
initial position in alignment with axis A and variable
selected positions spaced from axis A. Work piece engaging
means in the form of threaded stud 109 and shoulder 110,
as will be hereinafter described in greater detail~ are
carried proximate ~irst end 107 of pin 106. Opposed
parallel flats 111, sized to receive a conventional wrench
for rotation of pin 106 and located intermediate ends 107
and 108, are also integral with the working engaging means.
Annular groove 112, having radial shoulder 113, is
-formed in pin 106 proximate second end 108. Thrust member
114, having opposed sides 115 and 116, includes an elongate
slot 117 which is receivable by annular groove 112. Elongate
stem 119 extends from thrust member 114 and has hand grip
section 120 at the free end thereof. Thrust member 114 is
receivable through passage 101 concurrent with tool element
98 and is of sufficient length for hand grip section 120 to
project beyond edge surface 16 of plate 11 when thrust
member 114 is engaged with pin 106.
The function of the foregoing described embodiment
of the instant invention and the procedure for holding a
work piece in a machine tool in accordance with the instant
invention will now be described. Initially, plate 11 is
placed upon table 23 with base surface 13 against work
support surface 26. Utilizing T-nuts 72 and cap screws
73 the fixture is secured to table 23 in accordance with the
standard procedure for securing o~her well known ancillary
work holding devices to a machine tool table in accordance
3~
with conventional practice in the art. Also~ in accordance
with well known procedure, a base surface having tapped
holes extending inwardly therefrom is prepar0d on the work
piece. Generally, two or more ~apped holes are required
to rigidly affix the work piece and resist the forces o-f
machining operations.
,
Threaded stud 109 o-f pin 106 ls engaged with a
selected threaded hole within the work piece. A wrench
is engaged with flats 111 and pin 106 rotated until shoulder
110 firmly abuts the base surace of the work piece in a
manner analogous to tightening a conventional bolt. The
quantity of pins 106 engaged with the work piece is deter-
mined by the machine tool operator in order to obtain the
desired holding strength. An object of the instant inventive
embodiment is to alleviate the necessity of accurately tapped
holes. However, the holes must be located within pre-
determined zones. A zone is described as the circle
defined by aperture 48 in response to rotation of insert 32
For purposes of description, each insert 32 is
assumed to be at an initial position as illustrated in Fig. 9a.
First end 82 of thrust ring 78 is against annular shoulder 38
of counterbore 37, and first end 42 of insert 32 is near work
bearing surface 12 of plate llo The work piece is lowered
with pins 106 entering respective apertures 48 unkil the
base surface of the work piece rests upon work bearing
surface 12. As the work piece is lowered, appropriate
inserts 32 are rotated as necessary to bring apertures 48
into alignment with the respective pins 106. Subsequently,
the machine tool operator, holding hand grip section 120 of
stem llg, passes thrust member 114 through passage lO;L
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7~
engaging thrust member 114 with annular groove 112 of pin
106. This actîon is repeated until a thrust member 114 is
engaged with each pin 106.
Thereafter, each locking ring 79, associated with
an insert 32 having a pin 106 therethrough, is rotated.
To accomplish rotation of locking ring 79, the machine tool
operator grasps tool element 98 by hand grip end 100 and~
passing tool element 98 through passage 101, inserts engaging
end 99 into a bore 97. Tool element 98 is moved in a normal
tightening direction, usually clockwise, until either no
further movement Gf locking ring 79 is felt or until tool
element 98 strikes the side o passage 101. In the latter
case, tool element 98 is withdrawn from the immediate bore
97, repositioned in a subsequent bore q7, and the action
repeated. During the rotation of lock ring 79, thrust
ring 78 is cammingly moved in a direction away from annular
shoulder 38. Annular shoulder 85 of thrust ring 79, bearing
against annular shoulder 86 of insert 32, moves insert 32
along axis A in a direction away from work bearing surface
12 o plate 11. Pin 106 is also caused to move along axis A
in a direction away from work bearing surface 12, since
second end 43 of insert 32 bears against thrust member 114
which, in turn bears against radial shoulder 113 of pin 106.
Due to the movement of pin 106 and insert 32 in response to
rotation of locking ring 79, the base surface of work piece
57 is drawn firmly against work bearing surface 12.
Fig. 9b illustrates the fixture as it would appear
in the work holding position. The use of tool element 98
and stem 119 is best viewed in Fig. 10. The distance insèrt
32 must be retracted in order to bring work piece 57 against
- 2~ -
work bearing surface 12 is primarily a function of the
distance between shoulders 110 and 113 of pin 106 minus
the thickness oE thrust member 114, as measured between
opposed sides 115 and 116. In the initialy or work
receiving position, shoulder 113 must reside at a suf-
ficient distance from second end 43 of insert 32 to
receive thrust member 114 therebetween. A special location
of shoulder 113 is fixed by the abutment of the base of the
work piece against work bearing surface 12. Accordingly,
insert 32 is moved in a direction away from work bearing
surface 12 until contact is made between second end 43 and
side 115. As previously noted, the force of the contact -~
must be sufficient to immobilize the work pi.ece. The device
of the instant invention can be manufactured such that move-
ment of insert 32 along axis A need only b0 a few thousandths
of an inch.
The degrees through which locking ring 79 need be
rotated between the work receiving position and the work
holding position is generally a function of the helical
angle, or lead, of the complemental camming means between
thrust ring 78 and locking ring 79. In the immediate
embodiment, the cam means are in the form of external and
internal screw flights 95 and 96, respectivelyO As will
~e readily recognized by those skilled in the art, ~he use
of a sixteen ~itch single thread wiIl yield a lead distance
of .0625 inches. Accordingly, rotating locking ring 79
through 45 degrees will move insert 35 approximately .008
inches along axis A.
Por removal of the work piece~ locking ring 79 is
rotated in a counter direction, utilizing tool element 98.
- 25 -
Stem 119, with thrust member 114, is withdrawn from pin 106
and the work piece lifted from plate 11. Subsequently, pins
106 are withdrawn from the work piece and attached to another
work piece. Alternately, another work piece, having corres-
ponding pins 106 previously attachecl thereto, is affixed to
plate 11 as previously described.
.;
Work piece 57 may be affixed to plate 11 by means
other than the means previously described. Utilizing T-slot
50 or threaded apertures 52, the work piece is secured in
accordance with conventional practice.~ Alternately, pin 106
can be provided with a threaded aperture, or T-slot, extend-
in~ inwardly from shoulder 110 in lieu of threaded stud 109.
Pins 106 may also have an extended length to accommodate a
wor~ piece which is supported in a spaced relationship from
work bearing surface 12 by various stand-off devices, such
as those commonly referred to as parallels. Such modifica-
tions do not alter the function of the device as previously
described.
Other modifications and variations to the embodi-
men~ herein chosen for purposes of illustration will readily
occur to those s~illed in the art. Grub screw 103 selectively
retains ball 104 in groove 101 and provides for disassembly
of insert 32 from thrust ring 78. A spring residing in bore
102 and bearing against ball 104 will provide an equivalent
structure. Similarly, end 83 o~ thrust ring 78 may project
beyond end 43 of insert 32 and carry an internal snap ring
for retention purposes, as previously described in connection
with ring 47 for retai~ing locking ring 79.
- Where the advantages o~fered by slotted aperture
48 carried in rotatable insert 32 are not desired, insert 32
- 26 -
need not rotate. In the immediate alternate embodiment,
locking ring 79 can interact directly with insert 32,
Insert 32 is stabilized against rotation by a pin, similar
to pin 86, or other well known means, such,as a key and
key-ways. The external screw flight 95 is carried dlrectly
by second section 40 of insert 32. It will be appreciated
that either second section 40 must be enlarged, or inner
surface 90 of locking ring 79 reduced in size for mating
of the complemental camming means.
~. .
Plate 11 is readily securable to various ancillary
devices to facilitate particular machining operations.
For angular machining, plate 11 is secured to an angular
holding device, such as a sine plate, It is also envisioned,
for frequent and repetitive angle machining, that work bearing ~ ;
surface 12 be disposed at a pre-determined angle from base
surface 13. Holding a work piece at a pre-determined angle
is particularly advantageous in connection with certain long
range production runs,
.
Various changes and modifications to the embodi-
ments herein chosen for purposes of illustration will readily
occur to those skllled in the art. It is percelvable for
example that the size, configuration, number and placement
of spindles within a given pla~e is at the discretion of
the manufacturer. The number and placement of engagement
and receiving means associated with each spindle is simi-
larly readily alterable. Also, alternate shapes of the
plate and the engagement receiving means carried directly
thereby are readily subject to modification, To the extent
that such modifications do not depar~ from the spirit and
scope of the invention, they are to be viewed in terms of
the appended claims.
- 27 -
Having fully described and disclosed the present
invention and alternately preferred embodiments thereof
in such clear and concise terms as to enab:Le those skilled
in the art to understancl and practice the same, the inven-
tion claimed is:
~ ,:
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