Contour-abrasion means and method

Claim 2

A contour-abrading machine, comprising means for supporting an endless abrasive belt along a path of movement and for continuously driving the same along said path, said means including a stationary working platen having an external airpermeable convex wall contiguous to a part of said path and over which said belt is run in conformance with the external surface of said wall, pressure-fluid communicating means within said platen and communicating with the inner surface of said wall, whereby said belt is spaced from said wall by pressure fluid delivered through said wall, and pivotally mounted work-holding means for positioning work against said belt in the region of wall and fluid support thereof, the pivot axis being offset from a plane tangent to the belt as it leaves abrading contact with the work, and such offset being in the direction to develop a self-energizing work-feeding force component by reason of abrasive belt contact with the work.

Claim 3

A machine according to claim 1, in which said supporting means includes a pulley near to but spaced from the trailing edge of said wall, the belt course between said trailing edge and said pulley being sloped away from substantially the tangent to said wall at said trailing edge.

Claim 4

A machine according to claim 1, in which said platen has an interior bore forming part of said fluid-communicating means, and in which said wall is perforated with passages to said bore, the total perforation area at the external surface of said wall being in the order of 10 percent of the overall external surface area.

Claim 5

A contour-abrading machine, comprising means for supporting an endless abrasive belt along a path of movement and for continuously driving the same along said path, said means including a stationary working platen having an external air-permeable convex wall contiguous to a part of said path and over which said belt is run in conformance with the external surface of said wall, and pressure-fluid communicating means within said platen and communicating with the inner surface of said wall, said supporting means including a frame to which said platen is fixedly mounted, an idler pulley supported by said frame beyond the trailing edge of said wall to define the course of said belt as it leaves said platen, work-holding means having a pivotal reference connection to said frame on a fixed axis substantially parallel to the pulley axis and offset from the tangent plane of said belt at said trailing edge, the offset being in the direction such that, in the course of abrading a concave surface of work carried by said work-holding means, through belt contact in the region of said trailing edge, the pivotal approach of the work to said belt includes a self-energizing work-feeding force component.

Claim 6

A contour-abrading machine, comprising means for supporting an endless abrasive belt along a path of movement and for continuously driving the same along said path, said means including a stationary working platen having an external air-permeable convex wall contiguous to a part of said path and over which said belt is run in conformance with the external surface of said wall, and pressure-fluid communicating means within said platen and communicating with the inner surface of said wall, said supporting means including a frame to which said platen is fixedly mounted, an idler pulley supported by said frame beyond the trailing edge of said wall to define the course of said belt as it leaves said platen, work-holding means having a pivotal reference connection to said frame on a fixed axis substantially parallel to the pulley axis and offset from the tangent plane of said belt at said trailing edge, the offset being in the direction such that, in the course of abrading a concave surface of work carried by said work-holding means, through belt contact in the region of said trailing edge, the pivotal approach of the work to said belt includes a self-energizing work-feeding force component.

Claim 7

A machine according to claim 4, in which the work surface to be abraded has a trailing edge and in which said work-holding means includes means positioning the work such that the trailing edge contacts said belt at a location preceding belt paSsage over the trailing edge of said platen wall.

Claim 8

A machine according to claim 4, in which said supporting means includes a frame to which said platen is fixedly mounted, said work-holding means including a body and a work clamp, and means including a selectively adjustable pivotal connection between said body and said work clamp about an axis substantially parallel to the transverse dimension of said belt, whereby the angle of incidence of the abraded convex surface of the work may be selectively varied.

Claim 9

A contour-abrading machine, comprising a frame, an endless abrasive belt, means including spaced drive and idler pulleys for supporting and continuously driving said belt along a given path of movement, said support means including a frame-mounted working platen having an external convex wall contiguous to a part of said path and over which said belt is run in conformance with the external surface of said wall, fluid-pressure operated means directed for discharge at the concave surface of said belt as it passes over the external surface of said wall, whereby said pressure fluid relieves belt contact in the region of said platen, and pivotally mounted work-holding means for positioning work against said belt in the region of pressure-fluid support thereof, the pivot axis being offset from a plane tangent to the belt as it leaves abrading contact with the work, and such offset being in the direction to develop a self-energizing work-feeding force component by reason of abrasive belt contact with the work.

Claim 10

A contour-abrading machine, comprising a frame, an endless abrasive belt, means including spaced drive and idler pulleys for supporting and continuously driving said belt along a given path of movement, said support means including a frame-mounted working platen having an external convex wall contiguous to a part of said path and over which said belt is run in conformance with the external surface of said wall, fluid-pressure operated means directed for discharge at the concave surface of said belt as it passes over the external surface of said wall, whereby said pressure fluid relieves belt contact in the region of said platen, and pivotally mounted work-holding means for positioning work against said belt in the region of pressure-fluid support thereof, the pivot axis being offset from a plane tangent to the belt as it leaves abrading contact with the work, and such offset being in the direction to develop a self-energizing work-feeding force component by reason of abrasive belt contact with the work.

Claim 11

A machine according to claim 7, in which one of said pulleys is part of belt-tensioning means.

Claim 12

A machine according to claim 7, in which said convex wall is perforated and in which said fluid-pressure operated means directs pressure fluid through said wall.

Claim 13

A machine according to claim 9, in which said fluid-pressure operated means includes means for selectively varying the fluid delivery pressure at said wall.

Claim 16

The method of claim 11, in which the desired work contour is concave and in which the working platen surface is convex.

Claim 17

The method of claim 12, in which the air pressure is controlled to position the driven belt at a spacing in the order of 1 to 5 mils from the platen working surface.

Claim 18

The method of claim 12, in which the belt drive along said path is at a speed in the order of 6,000 feet per minute.

Claim 19

An abrasive machine for finishing the trailing-edge contour of a jet-engine vane having a given span between opposed buttresses, comprising rigid work-supporting means including a frame and spaced clamps for simultaneously clamping both buttresses in an orientation to expose the concave blade surface in a generally horizontal direction and with the trailing edge projecting downward, an endless abrasive belt and fixedly oriented means for supporting and continuously driving the same, said support means including a convex contoured air-permeable surface projecting generally horizontally, means forcing air through said surface to define an air cushion between said belt and said surface, the belt-drive direction being downward over said surface, and a fixed horizontal pivot support for said work-supporting frame, said pivot support being located below said air-permeable surface sufficient to position work in said supporting means in face-to-face relation with said belt as it traverses said air-permeable surface, and said pivot support being offset from the center of gravity of said work-supporting means to the extent that due to gravity action said work-supporting means tends to rotate in a first direction about said pivot support, said frame and clamps so orienting the work that the tangent plane which includes the trailing edge of the work piece is offset from the axis of said pivot support whereby a torque reaction to abrasion is developed substantially in said tangent plane, the direction of said last-mentioned offset being such as to place said reaction torque in offsetting relation with the torque due to gravity action on said work-supporting means about said pivot axis.

Claim 20

An abrasive machine for finishing the trailing-edge contour of a jet-engine vane having a given span between opposed buttresses, comprising rigid work-supporting means including a frame and spaced clamps for simultaneously clamping both buttresses in an orientation to expose the concave blade surface in a generally horizontal direction and with the trailing edge projecting downward, an endless abrasive belt and fixedly oriented means for supporting and continuously driving the same, said support means including a convex contoured air-permeable surface projecting generally horizontally, means forcing air through said surface to define an air cushion between said belt and said surface, the belt-drive direction being downward over said surface, and a fixed horizontal pivot support for said work-supporting frame, said pivot support being located below said air-permeable surface sufficient to position work in said supporting means in face-to-face relation with said belt as it traverses said air-permeable surface, and said pivot support being offset from the center of gravity of said work-supporting means to the extent that due to gravity action said work-supporting means tends to rotate in a first direction about said pivot support, said frame and clamps so orienting the work that the tangent plane which includes the trailing edge of the work piece is offset from the axis of said pivot support whereby a torque reaction to abrasion is developed substantially in said tangent plane, the direction of said last-mentioned offset being such as to place said reaction torque in offsetting relation with the torque due to gravity action on said work-supporting means about said pivot axis.

Claim 21

The machine of claim 15, wherein the pivot support is so located with respect to the region of contact that the center of gravity of said work-supporting means, when in working position, is operative about the pivot axis to develop a gravity torque urging said work-supporting means in the direction away from abrasive contact.

Claim 22

The machine of claim 15, wherein said tangent plane is so offset from said pivot axis that said torque reaction to abrasion is in the direction of self-energized work engagement with said belt.

Claim 23

An abrasive machine for finishing the trailing-edge contour of a jet-engine vane having a given span between opposed buttresses, comprising rigid work-supporting means including a frame and spaced clamps for simultaneously clamping both buttresses in an orientation to expose the concave blade surface in a generally horizontal direction and with the trailing edge projecting downward, an endless abrasive belt and fixedly oriented means for supporting and continuously driving the same, said support means including a convex contoured air-permeable surface projecting generally horizontally, means forcing air through said surface to define an air cushion between said belt and said surface, the belt-drive direction being downward over said surface, and a fixed horizontal pivot support for said work-supporting frame, said pivot support being offset from said air-permeable surface sufficient to position work in said supporting means in face-to-face relation with said belt as it traverses said air-permeable surface, said frame and clamps so orienting the work that the tangent plane which includes the trailing edge of the work piece is offset from the axis of said pivot support whereby a torque reaction to abrasion is developed substantially in said tangent plane and about the pivot axis, the direction of said last-mentioned offset being such as to develop said reaction torque in the direction of self-energized work engagement with said belt.

Claim 24

An abrasive machine for finishing the trailing-edge contour of a jet-engine vane having a given span between opposed buttresses, comprising rigid work-supporting means including a frame and spaced clamps for simultaneously clamping both buttresses in an orientation to expose the concave blade surface in a generally horizontal direction and with the trailing edge projecting downward, an endless abrasive belt and fixedly oriented means for supporting and continuously driving the same, said support means including a convex contoured air-permeable surface projecting generally horizontally, means forcing air through said surface to define an air cushion between said belt and said surface, the belt-drive direction being downward over said surface, and a fixed horizontal pivot support for said work-supporting frame, said pivot support being offset from said air-permeable surface sufficient to position work in said supporting means in face-to-face relation with said belt as it traverses said air-permeable surface, said frame and clamps so orienting the work that the tangent plane which includes the trailing edge of the work piece is offset from the axis of said pivot support whereby a torque reaction to abrasion is developed substantially in said tangent plane and about the pivot axis, the direction of said last-mentioned offset being such as to develop said reaction torque in the direction of self-energized work engagement with said belt.

Claim 25

The machine of claim 4, in which the course of belt movement over said convex wall is generally downward, in which said pivotal connection is below the elevation of work contact, and in which said offset is in the direction away from the pulley axis.

Claim 26

The machine of claim 4, in which the center of gravity of said work-holding means is offset from the axis of the pivotal connection, the latter offset being in the direction such that gravity produces a natural moment about said connection, said moment being in the direction opposite to that produced by said self-energizing force component.

Claim 27

An abrasive machine for finishing the trailing-edge contour of a jet-engine vane having a given span between opposed buttresses, comprising rigid work-supporting means including a frame and spaced clamps for simultaneously clamping both buttresses in an orientation to expose the concave blade surface in a generally horizontal direction and with the trailing edge projecting downward, an endless abrasive belt and fixedly oriented means for supporting and continuously driving the same, said support means including a convex contoured air-permeable surface projecting generally horizontally, means forcing air through said surface to define an air cushion between said belt and said surface, the belt-drive direction being downward over said surface, and a fixed horizontal pivot support for said work-supporting frame, said pivot support being located below said air-permeable surface sufficient to position work in said supporting means in face-to-face relation with said belt as it traverses said air-permeable surface, and said pivot support being offset from the center of gravity of said work-supporting means to the extent that due to gravity action said work-supporting means tends to rotate in the direction about said pivot support and away from work engagement with said belt.

Claim 28

An abrasive machine for finishing the trailing-edge contour of a jet-engine vane having a given span between opposed buttresses, comprising rigid work-supporting means including a frame and spaced clamps for simultaneously clamping both buttresses in an orientation to expose the concave blade surface in a generally horizontal direction and with the trailing edge projecting downward, an endless abrasive belt and fixedly oriented means for supporting and continuously driving the same, said support means including a convex contoured air-permeable surface projecting generally horizontally, means forcing air through said surface to define an air cushion between said belt and said surface, the belt-drive direction being downward over said surface, and a fixed horizontal pivot support for said work-supporting frame, said pivot support being located below said air-permeable surface sufficient to position work in said supporting means in face-to-face relation with said belt as it traverses said air-permeable surface, and said pivot support being offset from the center of gravity of said work-supporting means to the extent that due to gravity action said work-supporting means tends to rotate in the direction about said pivot support and away from work engagement with said belt.