US2570752A - Floating toolholder - Google Patents

Description

Oct. 9, 1951 M. L. BENJAMIN ET AL FLOATING TOOLHOLDER Filed March 24, 1948 IN VEN TORS ww Q E W N m EJ MW LW Bu M NR 7 my MB M.

Patented Oct. 9, 1951.

v NIT-ED .srrnrss PATENT OFFICE Milton L. Benjamin, shakerfleigh-ts an'd Frank- .Jyn (E. -Winnen, Cleveland, :Ohio said Winnen ass'ignor. tosaicIBenjamin I 7 Application Marh24, 1948, Serial No. 16,686

9 Claims. .1

The. present .improvements in floating "tool holders are especially concerned withrholders in which the shank and .tool holding members thereof are so connected to 'oneranother that the toolqheld in. the-latter can aligndtself with-a workpiece on "which :it is performing a cutting operation.

.Holders of thewcharacterreferred have their greatest utility -in:- conjunction with the machining of workpieces Which require successiveopera- :tions .by different tools, viz. :drilling followed by reaming, tapping .or't-hejlike, such holders wenabling production of high quality work and prolonging Ttool life in spite -.of inaccuracies in the co-axial disposition :of'thesecond operation tools relativerto thetaxes of theldrilled holeszori'the like in the workpieces. I

;Among .the primaryobj ects .of this invention are-to provideaa floating tool .holder which the tool holding member and thus the tool held thereinac-an *fully partake of :angular and @transverse movement relative to -theshank. member; in which an axial thrust bearingmeansinterposed between said members :is f ormedzso asnot to impede such angulari-and-transverse movement; in which a resilient element is the solezmeans em? ployed to provide for the aforesaid movements but yet the thrust bearing .means employed to preclude relative axial movement of. said members in one direction .does not-impede.thefirst-mentioned movements; and .in .Which .such -resilient element is so'formed that evenabnormally severe torsional. strains imposed onsaidmembersare not detrimental t the connections .of suchelement withsaid members.

Other .objects andadvantages will Ibecomeapparent asthe following descriptionproceeds.

j 1T0 Ithe accomplishment f :thefforego'ing and related'ends, said. invention, then comprises the features hereinafter fully described. and particularly pointed out in the claims, the following description and the annexed drawing -setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but afew of the various -ways'in which the principle oi the 'invention may be employed.

Insaid' annexedaidrawing .Fig. .1 is a .:central -:iongitu'diu-ial crossesection view diametrically "through 30118 :iembodiment of our invention Fig. -2 is across-sectiontiew"of the holder of Fig. 1 taken "substantially along the 'line :2-2

thereof;

:Fig.f3-.isia cross-section View: taken'along aplane normal to the axis threeofro'f a resilient element 2 'different'irom that. illustrated .in

and

.Fig. Lisa 'CI'OSS'SGGtiOTliViBW similar to Fig. 1 except illustrating a. modified formmftho'lder.

In the. embodiment of. the" inventiornillustrated in Figs. 1 and 2,;mimerald represents av shank member provided withianendf 2 :of the: usual form adapted for mounting :into an ;-appropriate machine, said shan'k'lhaving resil-iently connected theretoby ;means :of al'resilientielement :3, a tool gripping member l. .Althrustibearing iis :Linterposed between 'said members:t rprecluderrelative "axial movement thereof iin oneatdirecti'on.

Associated with said member tf 'lSTE'ICOHtIQCfiDIB collet -6iformed' with ."conical: cam'surfaces T-which are adapted toc'engageti ikeisurfaces in said member' wherebyzinward: movement- 0f said :collet into said member effects radial "contraction :of :the former: into firm gripping'engagem'ent with the shank of Ta .t'0D1"8fWhiChfiS herein 7 illustrated ras being a reamer. such -movement of the'collet is effected as by a nosepiece 9 ='engageab1e With the outer end thereof wander the iiifluence of a lock nut "I 0 having threaded engagement with-said memberi.

Threaded in said member fiis a set screw ll operating "215} an adjustable po'si'tive stop for the end "of the shank cr me tool' 8 whereby"thrust loads onsa'id tool are"not-'e'ifectiveto induce relative axial movement (if-said tool insaidmember '4. Thus;- in instances 'whereit is desired-that the tool enter thework =a-predetermined distance in accordance with the adjustment of 'set screw 1 I and the length of the tool8 taken in conjunction with the relative movements of the work carry ing andholder carrying devices of the machine, the tool cannot thereafter slip' 'axially' iii-member 4 to disturb this adjusted'relationship.

The resilient element 3"referred= to 'above'pref erably comprises an annulu's of rubber 'or'rubber like Vmaterial bonded or otherwise secured to metal .sleeve membersil'2 .and M respectively thereabout and therein. .Saidsleevemembers l2 and. I tare in turn. respectively fixed. againstlboth axial. and. rotativemovement inshankmember I and on tool .holding'member, A-asby forming the outerdiameter of sleeve-member t2 so-as-to have a drive or press fit in a counterbore 't-fizinrsaid shank member andbyiorming :the. inside diameterrof sleeve memberiMa-so asntothave asimilar fit .over the cylindricaliprojection .16 :of said :tool gripping -member. wosbviously other well known expedients may :be:u'sed:for;securingsaidsresilient element -in 'place abetweenssaid "-fmembers, :as, :for

Figs. .11 and 2 example, threaded connections, screws, broaching, swaging, etc.

It is now evident that with the structure thus far disclosed the tool holding member 4 including the tool 8 held thereby may partake of angular movement as indicated by the dot-dash lines IT as well as movement parallel to the axis of said shank member I whereby as the tool and work are brought together, any misalignment thereof will be corrected as the tool perform its cutting operation on the work. This arrangement reduces bending strains on the tool to a minimum, enables the tool to take an even bite to thus prolong the life of the tool and eliminates the chatter or vibration of the machine which would otherwise result if a rigid tool holder were employed.

Now in order that axial movement of said tool relative to said shank member be prevented during the cutting operation to enable accurate control of the depth to which said tool enters the work, we have provided, in addition to the set screw I I which prevents axial slipping of said tool in said holding member, a thrust bearing 5 for preventing axial movement of the holding member relative to the shank member. Asillustrated, said thrust bearing 5 comprises a stationary race I8 (fixed in shank I by press fitting or otherwise), a movable race I9, and a row of balls or like bearing elements carried in a retainer 2I between said races. The inner end of member 4 and said movable race I9 are formed with inter-engaging spherical faces 22 of radius R." With such construction it can be seen that any angular, parallel, or rotative movement or combinations thereof of the shank and holding members relative to one another as permitted by said resilient element will not disrupt inter-engagement of such spherical faces. Thus, the thrust bearing 5 will at all times be operative to prevent relative axial movement of said members but such prevention of relative axial movement is not at the expense of hindering the finding by'the tool 8 of a co-axial relationship to the drilled hole or other portion of the work inasmuch as the race I9 will always be freely movable in a plane normal to the axis of said shank member and when so moved is yet engaged by the spherical end of said gripping member.

In the resilient element illustrated in Fig. 3 the outer sleeve member 23 is formedwith a noncircular cross-section aperture therethrough to which the outer surface of the rubber or rubberlike annulus 25 is bonded and the inner sleeve member 21 is likewise formed with a non-circular cross-section, outer surface bonded to the inner surface of said annulus, the diagonal dimension D being such that under severe torsional strains, relative rotation of the sleeve members 23 and 21 and thus members I and 4 to which said element is connected, is positively arrested when the sleeve member 2? assumes the position illustrated by the dotted line 28, such arresting of relative rotation occurring before the aforesaid bonds of said annulus with said sleeve members are sheared. Such arrangement greatly enhances the life of the holder as a whole and requires less frequent replacement of the resilient element.

The modification illustrated in Fig. 4 is essentially the same as that of Figs. 1 and 2 except that the resilient element simply comprises a rubber or rubber-like annulus 29 having its outer and inner axially extending surfaces (circular or non-circular cross-section) respectively bonded engaged between said rings.

4 directly to the shank member 30 and to the too holding member 3|. Another distinguishing feature is that the thrust bearing only comprises a movable ring 32 formed with a spherical face 33 engaged by a corresponding face on the end of gripping member 3|. Said ring 32 is movable in a plane normal to the axis of shank member 30, as is the race I9 previously described, but because the balls 20 have been omitted such movement entails the overcoming of some friction between the ring 32 and the wall 34 of the shank member engaged thereby. However this friction is not sufficient to objectionably impede proper adjustment of the shank and holding members relative to one another with the tool held by the latter assuming a proper alignment with the work.

Having thus described several specific embodiments of our invention and the advantages accruing from the use thereof, it will be apparent to those skilled in the art that various modifications, in addition to those mentioned, may be made without departing from the spirit of the invention. Therefore, the disclosed structures are to be regarded as merely exemplary or typical especially with regard to the particular collets, shanks, and resilient elements that are shown, such parts of the combination being modifiable in many particulars to suit individual desires'or requirements.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

We therefore particularly point out and distinctly claim as our invention:

1. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members, a resilient element between said members connecting them together for movement to relative positions with the axes thereof misaligned or parallel to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction.

2. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members, a resilient element between said members connecting them together for movement to relative positions with the axes thereof misaligned or parallel to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction, said thrust bearing comprising a ring constantly engaged by one of said members and movable therewith in response to relative angular or parallel movement of said members.

3. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members, a resilient element between said members connecting them together for movement to relative positions with the axes thereof misaligned or parallel to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction, said thrust bearing comprising a first ring fixed in one of said members, a second ring engaged by the other of said members and movable trans versely therewith, and thrust bearing elements 4. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members, a resilient element between said members connecting them together for movement to relative positions with the axes thereof misaligned or parallel to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction, said thrust bearing comprising a ring constantly engaged by one of said members and movable therewith in response to relative angular or parallel movement of said members, the inter-engaged surfaces of said ring and said one of said members being spherical with the centers thereof coinciding with one another and lying along the axis of said.one of said members.

5. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members loosely i'itted one with the other whereby to define an annular space therebetween, a resilient element in such space connected to said members to thus connect said members for angular and parallel movement relative to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction.

6. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members loosely fitted one with the other whereby to define an annular space therebetween, a resilient element in such space connected to said members to thus connect said members for angular and parallel movement relative to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction, said bearing and one of said members being formed with inter-engaged spherical surfaces whose centers coincide with one another and lie along the axis of the latter.

7. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members loosely fitted one with the other whereby to define an annular space therebetween, a resilient element in such space connected to said members to thus connect said members for angular and parallel movement relative to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction, said bearing and one of said members being formed with inter-engaged spherical surfaces Whose centers coincide with one another and lie along the axis of the latter at a point generally corresponding with the point of intersection of a central transverse plane through said resilient element with the axis of said one of said members.

8. In a 'iioating tool holder, the combination of substantially co-axially disposed tool holding and shank members loosely fitted one with the other whereby to define an annular space therebetween, a resilient element in such space connected to said members to thus connect said members i or angular and parallel movement relative to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction, the walls of such space being respectively of non-circular cross-section and of such relative size that upon predetermined relative rotation of said members such Walls engage one another to arrest further relative rotation.

9. In a floating tool holder, the combination of substantially co-axially disposed tool holding and shank members loosely fittedone with the other whereby to define an annular space therebetween, a resilient element in such space connected to said members to thus connect said members for angular and parallel movement relative to one another, and a transversely movable thrust bearing engaged between said members limiting relative axial movement of said members in one direction, the walls of such space being respectively of non-circular cross-section and of such relative size that upon predetermined relative rotation of said members such walls engage one another to arrest further relative rotation, said resilient element being respectively, bonded to said members, such arresting of relative rotation occurring prior to shearing of such bonds.

MILTON L. BENJAMIN. FRANKLYN E. WINNEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Gideon Jan. 1, 1946

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