CA1103706A - Universal planetary clamping device - Google Patents

Abstract

UNIVERSAL PLANETARY CLAMPING DEVICE

Abstract A rigid plate having a work piece supporting surface is securable to a machine tool. A plurality of spindles, each rotatable about an axis perpendicular to the support surface, are journaled within the plate.
Engagement means carried by each spindle detachably received attachment means for affixing a work piece to the supporting surface. The location of each engagement means is movable relative the supporting surface in response to rotation of the respective spindle.

Description

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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.

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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 ~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.

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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.

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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.

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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, ~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;
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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 .

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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.
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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 ~ ~ ~ 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-~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-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

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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.

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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 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.

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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 .. ..
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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 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.

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 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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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.

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 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.

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:

~ ,:

Claims (17)

1. A fixture for use with a machine tool and for holding a work piece during machining operation by said machine tool, said fixture comprising:
(a) a substantially rigid plate having first work supporting surface and a second spaced opposed surface;
(b) a generally cylindrical bore extending through said plate between said first work supporting surface and second surface thereof;
(c) a spindle having first and second ends and an outer generally cylindrical surface and journaled within said bore for rotation about the longitudinal axis of said bore; the first end of said spindle being positioned proximate but slightly recessed from the first work supporting surface of said plate;
(d) first retention means for limiting the axial movement of said spindle in a direction toward the first work supporting surface of said plate; and (e) engagement receiving means carried by said spindle for receiving means for securing said work piece against the first work supporting surface of said plate.

2. The fixture of Claim 1, wherein said first retention means includes:

a) a first annular shoulder extending radially inward from said base; and b) a second annular shoulder extending radially outward from said spindle and received against said first shoulder.

3. The fixture of Claim 1, further including second retention means cooperating with said first retention means for retaining said spindle within said bore.

4. The fixture of Claim 3, wherein said second retention means includes:

a) an annular groove extending radially outward from said bore into said plate;
and b) an annular ring member carried in said groove and extending radially inward to receive the second end of said spindle thereagainst.

5. The fixture of Claim 1, wherein said engagement receiving means comprises a radial slot extending through said spindle between the first and second ends thereof.

6. The fixture of Claim 5, wherein said slot extends radially from proximate the center of said spindle to proximate the outer surface of said spindle.

7. The fixture of Claim 6, wherein said slot defines an opening along the outer surfaces of said spindle.

8. The fixture of Claim 1, wherein said engagement receiving means includes a T-slot extending diametrically along the first end of said spindle.

9. The fixture of Claim 1, wherein said engagement receiving means includes an internally threaded bore extending inwardly from the first end of said spindle and having a longitudinal axis substantially parallel to the longitudinal axis of said spindle.

10. The fixture of Claim 9, further including a plurality of spaced, annularly arranged, internally threaded bores extending inwardly from the first end of said spindle, each said bore having a longitudinal axis substantially parallel to the longitudinal axis of said spindle.

11. The fixture of Claim 1, further including engage-ment receiving means carried by said plate.

12. The fixture of Claim 1, further including means for detachably securing said plate to said machine tool.

13. The fixture of Claim 1, wherein said plate is generally rectangular, having first and second longitu-dinal edges and first and second lateral edges.

14. The fixture of Claim 13, further including a first base plate carried by said rigid plate proximate a longi-tudinal edge thereof and having a bottom surface substan-tially perpendicular to the first surface of said rigid plate.

15. The fixture of Claim 14, further including a second base plate carried by said rigid plate proximate a lateral edge thereof and having an outer surface subs-tantially perpendicular to the first surface of said rigid plate.

16. The fixture of Claim 1, wherein said rigid plate is generally cylindrical,

17. The fixture of Claim 16, further including means carried by the second surface of said rigid plate for attaching said fixture to a machine tool.