GB2106431A - Fixed diameter single pass cutting tool - Google Patents

Abstract

A single pass cutting tool includes a body (20) having a plurality of guide surfaces (36, 38) defining stone recesses and means for guiding abrasive stones (22) into an adjustable fixed diameter cutting position. A tapered arbor (16) engages inboard surfaces (46) of the stones (22) to establish the size of the cutting section of the tool, and adjustable means (18, 58) are provided to translate relatively the arbor (16) and inboard surfaces (46) to adjust the diameter of the cutting section and to lock it in position. The expandable construction is particularly suitable for an abrasion tool and may have abrasive particles secured to the cutting section. In another embodiment, the abrasive stones (100) are adjustable along inclined bottom surfaces of recesses (94) and fixedly secured in their adjusted position by wedge-shaped clamps (104). <IMAGE>

Description

SPECIFICATION Fixed diameter single pass cutting tool This invention relates to an adjustable single pass cutting tool including a multi-layer abrasive cutting section and a translatable arbor to adjust and fix the size of the cutting tool.

An expandable cutting tool, having a cutting section that adjusts as it is rotated and axially inserted within a bore to be machined, is known.

For example, U.S. Patent No. 1,791,491 discloses a honing tool having a spring biased arbor that provides tool alignment as the tool is rotated and moved axially in a bore through several passes progressively, to enlarge the hole on each pass.

U.S. Patent No. 4,075,794 discloses a multi-pass honing tool with a tapered arbor that aligns the tool as it is rotated and moved axially within a bore to be machined, and which includes an axially positioned spring to bias the stones outwardly of a body.

An object of the invention is to provide an improved single pass cutting tool for machining a bore upon tool rotation and single pass axial movement through the bore to remove a predetermined amount of stock.

In accordance with the invention a cutting tool includes a cutting section having a plurality of abrasive stones with a cutting portion adjustably positioned by an arbor located in the tool body and associated with relatively translatable stone positioning surfaces inclined to position the cutting portion at a required surface pass cutting diameter. A portion of the surface of the arbor has a diameterwhich is larger than the diameter defined by the space between a portion of the small end of a stone positioning surface of the abrasive stones and smaller than the diameter of the cylindrical cutting portion whereby the arbor can be releasably held in a fixed position with respect to the abrasive stones to hold a required single pass cutting diameter. Such a construction provides proper tool alignment upon a single pass tool rotation and axial movement through a bore to be machined.Initial sizing of the tool and sizing thereof to compensate for wear, adjusts the cutting portion to the required single pass size so as to machine the bore to the required size and provide proper tool alignment during the machining.

In a preferred construction, the cutting tool includes a single cone-shaped arbor axially positioned with respect to a tool body by a threaded stud connected to the arbor and threaded through a nut fixed to the body. A tapered surface of the cone engages an inclined surface on each of the abrasive stones to locate them to define a single pass cutting diameter.

Circular springs seated in annular body grooves and stone grooves hold the stones inwardly of the body during single pass tool rotation and movement through the bore. Wear compensation is produced by adjusting the position of the arbor by translating it with respect to the cutting section so as to locate it at a desired preset cutting diameter from single pass stock removal from the bore.

The tool of the invention is particularly suitable for use with abrasion cutting, although other uses are possible. In the preferred embodiment, a unitary tool body has plural recesses to guide the stones both radially and axially so as to define a cutting section of fixed form. An inner tapered surface on each stone provides for mounting the stones on a tapered arbor. Relative axial translational movement between the arbor and stones establishes the size of the tool. Initial sizing of the tool for use in thus facilitated and wear of the abrasive particles can be compensated for by arbor movement with respect to the stones to maintain the tool size for a required single pass stock removal.

The invention will now be described by way of example, with reference to the drawings, in which:~ Figure 1 is a longitudinal section of one embodiment of tool in accordance with the invention, shown mounted on a rotatable and axially movable tool chuck; Figure 2 is a cross-section on plane 2-2 of Figure 1 looking in the direction of the arrows; Figure 3 is a cross-section on plane 3-3 of Figure 1 looking in the direction of the arrows; Figure 4 is a side elevation of another embodiment; Figure 5 is an end elevation of the embodiment of Figure 4; Figure 6 is a fragmentary, enlarged elevation of a cutting tool holder in the embodiment of Figure 4; Figure 7 is a fragmentary, enlarged crosssection on plane 7-7 of Figure 5 looking in the direction of the arrows;; Figure 8 is a side elevation of a diamond abrasion tool used in the embodiment of Figure 4; Figure 9 is an end elevation of the tool of Figure 8; and Figure 10 is a perspective view of the tool of Figure 1.

A first embodiment of a single pass cutting tool 10 is shown in Figures 1-3 and 10. The tool 10 is mounted on a spindle chuck 12 for rotation about an axis to provide single pass machining of a bore upon axial tool movement through the bore.

Cutting tool 10 includes a plurality of adjustable cutting sections 14, an adjustable arbor 16 and a threaded adjusting stud 18 at the trailing end of the tool.

The tool 10 includes a unitary tool body 20 made from for example of steel. The body 20 has a plurality of abrasive stones 22 each with an arcuate cutting surface 24 of abrasive particles, for example diamond or cubic boron nitride, secured thereto in a manner such as to define a multi-layer abrasive stone which increases usable abrasive volume in a finishing process.

The tool 10 is used in a single pass operation wherein it is fed through a workpiece bore in a single pass for removal of stock and then is withdrawn from the bore during a retract cycle.

Such one-pass finishing operations will size the bore to close size, roundness and straightness tolerances. The tool 10, as will be discussed, is preset to a fixed diameter to prevent manufacture of oversized bores. As the tool 10 is fed through the workpiece bore, it is rotated to generate the preset tool diameter through the bore.

Usually, stock removal during each single pass is comparatively small and limited to a maximum of a few thousandths of an inch. When stock removal requirements exceed that obtained by single tool pass stock removal, one or more additional tools may be arranged, preferably inline, with each single pass station having a tool of progressively greater diameter to produce a required final workpiece bore diameter without exceeding the capacity of a tool for single pass stock removal. Each single pass station can be equipped with an in-process gauge system.

Single pass stock removal and repeatability of the removal for a number of workpieces is in part due to the configuration and fit of each abrasive stone 22.

In the present embodiment the tool body 20 has three circumferentially spaced recesses 26.

Each recess 26 receives a stone 22. Spaced, parallel, side-walls 28, 30 of each recess 26 engage and slidably guide the side surfaces 32, 34 of each stone 22. The side surfaces 32, 34 firmly secure the stones 22 against machine torque when the tool is preset to its desired stock removal diameter. Likewise each recess has opposite end surfaces 36, 38 which support the ends 40, 42 of each stone 22 to prevent axial shift of the stones during feed and retract of the tool 10.

Further, each stone 22 has an inboard surface 46 which is inclined with respect to a cutting section 48 which is bounded at its outboard end by the arcuate cutting surface 24.

The surfaces 46 engage the tapered outer surface 50 of the arbor 16 to adjust the surfaces 24 to a pre-set cutting section diameter.

Adjustment of the arbor 16 is accomplished by a threaded stud 52 secured to the small diameter end 54 of arbor 16 by a jam nut 56. The stud 52 is threadedly received by a nut 58. Nut 58 is seated in a counterbore 60 of body 20. Three equidistantly, circumferentially spaced set screws 62 in body 20 engage grooves 64 in the nut 58 to secure it against rotation relative to body 20.

Consequently, rotation of the arbor 16 will cause it to be translated relative to surfaces 46 to adjust the abrasive stones 22 to a required pre-set diameter for single pass removal of stock.

The outside diameter of the large diameter end of arbor 16 has serrations 66 formed therein at a precalibrated circumferential spacing to reflect a predetermined amount of tool cutting section diameter change for each increment of rotation of arbor 16. A spring plunger 68 is seated in an end bore 69 of body 20 to ride into and out of the serrations 66. This produces an audible indication and retention of the adjusted position of arbor 1 6 and allows calibration of diameter change to compensate for wear of stones 22.

Each abrasive stone 22 is held inboard of the recess side walls 28, 30 and end surfaces 36, 38 by a pair of circular springs 70, 72 seated in arcuate grooves 74, 76 formed at axially spaced locations in the body 20. Each abrasive stone 22 also includes spaced spring grooves 78, 80 aligned with body grooves 74, 76 to seat the springs 70, 72 substantially inboard of the cutting surfaces 24 so as to ensure that the tool 10 can be adjusted for wear without exposing the springs.

Further, the tool body 20 includes an extension 80 with a small diameter end 82 received by a chuck and an intermediate diameter portion 84 which slidably supports a gauge plug.

In operation, the arbor 16 is rotated to cause nut 56 and stud 52 to translate the arbor 16 axially into or out of the body 20. Movement of the arbor 16 into the body 20 will increase the single pass stock removal diameter of the cutting section 14.

Movement of the arbor 1 6 outwardly of the body 20 will reduce the diameter of the cutting sections 14. This adjustment is readily adaptable to automatic tool adjustment systems wherein arbor rotation and consequent translation is produced by directing a rotatable compensation shaft 86 through a bore 88 in the extension 90.

Another embodiment is shown in Figures 4 to 9. A presettable, fixed diameter, single pass tool 90 includes a unitary body 92 having a plurality of tool recesses 94 located at circumferentially spaced locations. Each recess has spaced side walls 96, 98 which support a pair of abrasive inserts 100. More particularly, a side 102 of an abrasive insert 100 is supported by wall 96. An opposite side 104 of another insert 100 is supported by wall 98. Opposite sides 102,104 of the pair of inserts 100 engages the sides 106, 108 of an insert clamp 110.

Each insert clamp 110 is wedge shaped as shown in Figure 5 and is held in place by a pair of screws 112,114 (Figure 4) to secure the abrasive inserts 100 positively in place on the body 92 so as to establish a cutting section of fixed diameter as defined by cutting surface 11 6 on the inserts 100.

Adjustment of the fixed diameter is accomplished by relative translational movement between an inclined surface 11 8 at the bottom of each recess 94 and an inclined ramp 120 on the base of each abrasive insert 100. To increase diameter, each clamp 110 is released by backing screws 1 12. 1 14 from a shoulder 122 inboard of each clamp 110. The inserts 100 are thus released and are free to be translated axially which movement will cause the inserts 100 to shift ou#twardly of the recesses 94. Increase in tool diameter is produced by reverse movement of the inserts 100. Following adjustment of the insert clamps 110 are wedged against the inserts to fix the desired diameter once the screws 112,114 are threaded into the body sufficiently to engage shoulder 122 tightly.

The above described embodiments disclose fixed diameter cutting tools configured to produce single pass finishing operations for improved hole size, roundness and straightness.

Claims (10)

1. A single pass cutting or abrasive tool comprising a tool body, a cutting section fixedly connectable to the body to maintain a single pass cutting diameter for removing a predetermined amount of stock from a workpiece bore during single pass axial and rotary movement of the tool through the bore, the cutting section including a plurality of abrasive stones each having an abrasive cutting face and each having surfaces thereon guidingly supported by the body, each stone further including an axially inclined positioning surface, relatively inclined support surface means within the body engageable with each positioning surface and relatively axially translatable with respect to each positioning surface to adjust the diameter of the cutting section, and adjustment means to fix the cutting section at an adjusted diameter whereby the cutting section is presettable to an initial single pass cutting diameter and resettable to that diameter to compensate for wear.

2. A single pass cutting or abrasive tool comprising a tool body, a cutting section fixedly connectable to the body to maintain a single pass cutting diameter for removing a predetermined amount of stock from a workpiece bore during single pass axial and rotary movement of the tool through the bore, the cutting section including a plurality of abrasive stones each having an arcuate cutting face and each having surfaces thereon guidingly supported both axially and circumferentially by the body to counteract torque and thrust loading during removal of stock from the workpiece, each stone further including an axially inclined positioning surface, an arbor within the body having a large diameter end extending from the body and including a tapered surface thereon engageable with each inclined positioning surface and relatively axially translatable with respect to the positioning surfaces to adjust the diameter of the cutting section, and adjustment means to secure the cutting section, and adjustment means to secure the cutting section at an adjusted diameter whereby the cutting section is presettable to an initial single pass cutting diameter and resettable to the single pass cutting diameter to compensate for wear.

3. A tool according to claim 2, wherein each stone positioning surfaces has an outboard end with a space therebetween, a portion of the tapered surface of the arbor having a diameter which is larger than the diameter defined by the space between the outboard ends of the stone positioning surfaces and smaller than the diameter of the arcuate cutting faces of the cutting section, whereby the arbor can be releasably held in a fixed resettable position with respect to the stones to reset an initial single pass cutting diameter.

4. A tool according to claim 2, wherein the arbor is of single cone shape axially positioned with respect to the tool body, the tapered surface of the cone engaging the inclined positioning surfaces on each stone to locate the stones to define the single pass cutting diameter, the body and the stones having outboard grooves therein, circular springs seated in the body grooves and the stone grooves to hold the stones inwardly of the body against the arbor during single pass axial and rotary movement of the tool through the bore, adjustable means for holding the arbor in place, the arbor and circular springs holding the stones therebetween to maintain the single pass cutting diameter and to prevent radial movement of stones during movement of the tool through the bore.

5. A tool according to claim 1 comprising a unitary tool body with plural recess-forming guide means to guide the stones both radially and axially so as to define a cutting section of fixed form, each stone having layers of abrasive material thereon, each positioning surface having an inner tapered surface on each stone, a tapered arbor engaging the support surface whereby wear of abrasive particles can be compensated by arbor movement with respect to the stones to reset the tool size to an initial diameter and wherein the layers of abrasive material increase the usable abrasive grit volume to compensate wear.

6. A tool according to claim 1 wherein each stone has at least one side surface in engagement with the body, two pairs of the stones having a space therebetween, a wedge-shaped clamp located within the space, and means to secure the clamp to the body to secure the stones at pluralities of axial positions in the body, the inclined support surface and the positioning surface coacting when the stones are at the said plurality of axial positions to variably adjust the single pass cutting diameter of the cutting section.

7. A tool according to claim 1 wherein the support surface means including a rotatable surface, the adjustment means including rotary thread means operable upon rotation of the support surface means to position the support surface means axially.

8. A tool according to claim 2, wherein the arbor is relatively rotatable with respect to the body, a small diameter end on the arbor, means including a screw thread on the said small diameter end operable upon rotation of the arbor to translate it axially with respect to the body.

9. A tool according to claim 7, wherein the adjustment means includes a plurality of serrations in the support surface means, and pin means in the body spring biased into one of the serrations to hold the support surface means with respect to the body.

10. A tool according to claim 8, wherein the adjustment means includes a plurality of serrations in the large diameter end of the arbor, and pin means in the body spring biased into one of the serrations to hold the arbor with respect to the body and to allow calibrated adjustment of tool diameter to compensate for wear.

1 1. A single pass cutting or abrasive tool constructed and arranged substantially as herein described and shown in the drawings.