Clamping apparatus for a machine tool

Claim 2

In a machine tool comprising, support structure, a spindle sleeve carried by said support structure and adapted to receive slidably a machining tool spindle, bearing means rotatably supporting said spindle sleeve, such that said sleeve and an operably connected machining tool spindle may be rotated relative to said support structure; clamping means for adjustably securing said machining tool spindle in a predetermined axial position relative to said spindle sleeve, said clamping means including; a clamp bore formed in said spindle sleeve, an annular clamp bushing disposed within said bore, said bushing and clamp bore defining an elongate circumferentially continuous plenum chamber and a pair of axially spaced annular land portions, one said land portion disposed at each end of said chamber, a fluid path for operably connecting said plenum chamber with a source of highpressure operating fluid whereby said fluid may be introduced into said chamber to contract and force said bushing into rigid clamping engagement with a machining tool spindle disposed within said spindle sleeve, and said bushing in the unassembled condition having a maximum outer diameter greater than the minimum diameter of said clamp bore to provide an interference fit therebetween in the assembled condition, such that at each said land portion said spindle sleeve is in compressive engagement with said bushing to establish residual stresses therein.

Claim 3

Clamping means as defined in claim 1, further including high-pressure fluid supply means carried by said spindle sleeve, said fluid supply means being operably connected to said fluid path for supplying operating fluid to said plenum chamber.

Claim 4

Clamping means as defined in claim 1 wherein the radial width of said plenum chamber is extremely small to hinder the displacement of operating fluid.

Claim 5

Clamping means as defined in claim 1, wherein the wall of the bushing portion underlying said plenum chamber is relatively thick, so as to provide a substantially rigid clamp bushing, wherein upon contraction of said underlying bushing portion, the end portions thereof will be expanded into increased compressive engagement with the sleeve.

Claim 6

Clamping means as defined in claim 1 wherein said circumferentially continuous plenum chamber is defined by an elongate groove formed in the outer peripheral surface of said clamp bushing, which groove defines axially spaced lands on said bushing.

Claim 7

Clamping means as defined in claim 5, wherein said clamp bushing includes a pair of axially spaced annular seal grooves formed in the outer surface thereof, one of said pair being disposed at each end of said elongated peripheral groove to define the axial extremities thereof, and an annular seal disposed in each said seal groove and in engagement with said clamp bore.

Claim 8

Clamping means as defined in claim 5, wherein said elongate groove is shallow, such that the said circumferentially continuous plenum chamber is extremely small in radial width to hinder the displacement of operating fluid during operation, and thereby dampen the vibrations of said spindle.

Claim 9

Clamping means as defined in claim 5 wherein the portion of said bushing underlying said groove is relatively thick in radial section, so as to provide a substantially rigid junction between said underlying portion and the end portions of said bushing, such that upon contraction of said underlying portion by operating fluid, the end portion thereof will expand to establish compressive forces which augment those created upon assembly.

Claim 10

In combination; a machine tool including, support structure, a spindle sleeve carried by said support structure and adapted to receive slidably a machining tool spIndle, bearing means rotatably supporting said spindle sleeve, such that said sleeve and an operably connected machining tool spindle may be rotated relative to said support structure; and clamping means for adjustably securing said machining tool spindle in a predetermined axial position relative to said spindle sleeve, said clamping means including, a clamp bore formed in said spindle sleeve, an annular clamp bushing disposed within said bore, said bushing and clamp bore defining an elongate, circumferentially continuous plenum chamber, and a pair of axially spaced annular land portions, one disposed at each end of said chamber, a fluid path for operably connecting said plenum chamber with a source of high-pressure operating fluid whereby said fluid may be introduced into said chamber to contract and force said bushing into rigid clamping engagement with a machining tool spindle disposed within said spindle sleeve, and said bushing in the unassembled condition having a maximum diameter greater than the minimum diameter of said clamp bore to provide an interference fit therebetween in the assembled condition, such that at each said land portion said spindle sleeve is in compressive engagement with said bushing to establish residual stresses therein, which stresses assist in maintaining said compressive engagement throughout the clamping operation.

Claim 11

In combination; a machine tool including, support structure, a spindle sleeve carried by said support structure and adapted to receive slidably a machining tool spIndle, bearing means rotatably supporting said spindle sleeve, such that said sleeve and an operably connected machining tool spindle may be rotated relative to said support structure; and clamping means for adjustably securing said machining tool spindle in a predetermined axial position relative to said spindle sleeve, said clamping means including, a clamp bore formed in said spindle sleeve, an annular clamp bushing disposed within said bore, said bushing and clamp bore defining an elongate, circumferentially continuous plenum chamber, and a pair of axially spaced annular land portions, one disposed at each end of said chamber, a fluid path for operably connecting said plenum chamber with a source of high-pressure operating fluid whereby said fluid may be introduced into said chamber to contract and force said bushing into rigid clamping engagement with a machining tool spindle disposed within said spindle sleeve, and said bushing in the unassembled condition having a maximum diameter greater than the minimum diameter of said clamp bore to provide an interference fit therebetween in the assembled condition, such that at each said land portion said spindle sleeve is in compressive engagement with said bushing to establish residual stresses therein, which stresses assist in maintaining said compressive engagement throughout the clamping operation.

Claim 12

The combination as defined in claim 9, wherein said clamp bushing has an elongate, annular groove which cooperates with said bore to define said plenum chamber and said land portions being defined by the end portion of said bushing.

Claim 13

The combination as defined in claim 10, wherein said elongate groove is shallow in depth, such that the radial width of the resulting plenum chamber is relatively small, whereby during operation, the displacement of operating fluid in said chamber is impeded and the vibrations of said spindle are accordingly dampened.

Claim 14

The combination as defined in claim 9, wherein the bushing wall portion underlying said chamber is relatively thick to provide a substantially rigid juncture between said underlying portion and the end portions of the bushing, such that upon contraction of said underlying portion, said end portions will be flared radially outward to establish compressive forces which augment those created during assembly.

Claim 15

The combination as defined in claim 12, wherein said plenum chamber is defined by an elongate groove formed in the outer periphery of said bushing, intermediate the ends thereof.

Claim 16

The combination as defined in claim 13 wherein said groove is shallow.