TOOLS FOR ROUGH FINISHING AND HONING BORES
United States Patent 3710518
A lapping tool includes a split, distendable, sleeve having alternate relatively coarse abrasive portions and relatively fine abrasive portions, the sleeve surrounding a plurality of wedge-like members arranged in two sets and carried by a slotted tool body. One set of wedge-like members lies inwardly of the coarser grained portions of sleeve and another set lies inwardly of the finer portions. The wedge angles of the first set are shallower than the second set so that as an expander acts progressively on the wedge-like members, the coarser portions of the sleeve are initially forced into contact with the bore of a workpiece and the finer portions are subsequently forced out beyond the coarser portions.
US Patent References:
Hone
Palotsee - June 1952 - 2599009
GRINDING TOOLS
Henry-Biabaud - August 1969 - 3458961
Hone
Palotsee - June 1952 - 2599009
GRINDING TOOLS
Henry-Biabaud - August 1969 - 3458961
Application Number:
05/159117
Publication Date:
01/16/1973
Filing Date:
07/02/1971
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Export Citation:
Assignee:
Societe Anonyme Automobiles Citroen (Paris, FR)
Primary Class:
International Classes:
B24B33/08; B24B33/00; B24B9/02
Field of Search:
51/338-346
Primary Examiner:
Simpson, Othell M.
Claims:
I claim
1. In a lapping tool
2. A lapping tool according to claim 1, in which the first set of surfaces of the expander alternate with the second set of surfaces.
3. A lapping tool according to claim 1, in which the inclined surfaces of the expander form the bases of grooves provided in the expander.
4. A lapping tool according to claim 1, in which all the abrasive surfaces of the tool are carried by said sleeve, the periphery of which sleeve has longitudinal grooves separating portions of the sleeve with relatively finer and coarser abrasive.
5. A lapping tool according to claim 1, comprising a projection rigid with one of the thrust members engaging in an opening in the sleeve.
1. In a lapping tool
2. A lapping tool according to claim 1, in which the first set of surfaces of the expander alternate with the second set of surfaces.
3. A lapping tool according to claim 1, in which the inclined surfaces of the expander form the bases of grooves provided in the expander.
4. A lapping tool according to claim 1, in which all the abrasive surfaces of the tool are carried by said sleeve, the periphery of which sleeve has longitudinal grooves separating portions of the sleeve with relatively finer and coarser abrasive.
5. A lapping tool according to claim 1, comprising a projection rigid with one of the thrust members engaging in an opening in the sleeve.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tool for rough finishing and honing bores in workpieces.
2. Description of the Prior Art
In micro-machining or honing work, it is conventional for the workpiece bore to be initially rough finished with a first lapping tool that has coarse-grained abrasive faces and then to be finished with a second lapping tool having finer-grained abrasive faces which effected the required honing. It is therefore necessary either to use two separate lapping machines or alternatively to stop the single machine and replace one lapping tool by another.
An object of the present invention is to provide a combination lapping tool with which a bore can be rough finished and immediately honed without the need for stopping the machine.
SUMMARY OF THE INVENTION
According to the present invention there is provided in a lapping tool a hollow body, a plurality of first radially displaceable thrust members protruding from the body, each said first thrust member having a radially inner face inclined to the longitudinal center line of the body, a plurality of second radially displaceable thrust members protruding from the body, each said second thrust member having a radially inner face inclined to the longitudinal center line of the body by an angle greater than that of the first thrust members, an expandable split sleeve surrounding the thrust members and having first portions thereof coated with a relatively coarser abrasive and second portions coated with a relatively finer abrasive, an expander displaceable within the body and having two sets of surfaces, one set being inclined to the longitudinal axis of the body at an angle corresponding to the inclination of the first thrust members and the other set being inclined at an angle corresponding to the inclination of the second thrust members, the surfaces of said two sets being in contact with the corresponding inclined surfaces of the thrust members and the first portions of the sleeve lying radially outwardly of the first thrust members and the second portions of the sleeve lying radially outwardly of the second thrust members.
With this construction, any given axial displacement of the expander will result in greater radial displacement of the thrust members situated opposite the fine-grained surfaces.
At the start of the honing operation, the thrust members opposite the coarse-grained surfaces protrude farther than the others, so that only those surfaces are brought into play, enabling rough finishing to proceed. As the work progresses, the expander is displaced within the body by conventional means and causes radial displacement of the various thrust members. There comes a moment when the thrust members opposite the fine-grained surfaces protrude more than the others, so that, from that moment on, only these surfaces are in action, enabling the finishing stage to proceed.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of a lapping tool in accordance with the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:
FIG. 1 is an axial section of the lapping tool;
FIG. 2 is a cross-section on the line II--II of FIG. 1;
FIG. 3 is a side elevation of part of the tool;
FIG. 4 is a cross-section on the line IV--IV of FIG. 1; and
FIGS. 5 to 7 indicate diagrammatically the movements of thrust members forming parts of the tool, the amount of displacement having been exaggerated in the interest of clarity.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The combination lapping tool illustrated comprises a body 1, one end of which carries two lugs 1a, connected to an internal ring 2, by two coaxial pins or other members 3a; the ring 2 is in turn connected to two lugs 4a, on a drive spindle 4, by two pins or other coaxial members 3b, which have their common longitudinal center line at right angles to that of the pins 3a. Hence, the body 1 is constrained to rotate with the spindle 4, to which it is connected by the universal joint formed by the lugs 1a and 4a and the pins 3a and 3b.
The body 1 has longitudinal slots or other openings 5, in which thrust members 6 and 7 are received, the members 6 alternating with the members 7. These thrust members fit into longitudinal grooves 8 and 9 respectively, in a mandrel 10, which is movable in a longitudinal bore in the body 1. This mandrel 10 is connected by a pin 11 and other parts to an expansion control rod 12, which is movable axially within the spindle 4.
The base of the grooves 8 is inclined at a gradient, p1, of, for example, 1 percent, the inner or bottom face of the corresponding thrust members 6 being similarly inclined. Displacement of the mandrel 10 in the axial direction indicated by the arrow F (FIG. 1) will therefore result in radial outwards displacement of the thrust members 6.
In the same way, the base of the grooves 9 is inclined at a gradient p2, but this is greater than p1, being, for example, 1.5 percent, and the inner or bottom face of the thrust members 7 is similarly inclined. Displacement of the mandrel 10 in the direction of the arrow F will therefore result in radial outwards displacement of the thrust members 7, this displacement being greater than that of the members 6.
A honing sleeve 13, split axially at 14, is mounted under tension over the assembly of thrust members 6 and 7 and thus to bias these members into contact with the base of the grooves 8 and 9. In that opening 5 in the body 1 which immediately precedes the split 14, considered in the direction of rotation of the body 1, lies a thrust member 7a, which is similar to the thrust members 7 but carries two projections 15, which engage in openings 16, in the sleeve 13. The purpose of these projections is twofold; to rotate the sleeve 13 and to fix the angular position of the sleeve in relation to the thrust members 6 and 7, so as to prevent these thrust members from changing position in relation to the sleeve.
The periphery of the sleeve 13 has longitudinal grooves 17, each of which, when the sleeve is in position on the body, lies equidistant from one thrust member 6 and one thrust member 7. These grooves 17 divide the peripheral face of the sleeve into segments equal in number to the number of thrust members, each segment lying opposite one of these. The grooves constitute weakened zones and thus enable the sleeve to undergo limited deformation.
Those segments of the sleeve 13 which lie opposite thrust members 6 are serrated at 18 and coated with an abrasive substance, consisting, for example, of a diamond-charged compound. The segments 19 opposite thrust members 7 are likewise serrated and coated with an abrasive substance consisting, for example, of a diamond-charged compound, but this is finer-grained than that of the abrasive substance on serrations 18.
Apertures 20 are provided in the bases of the grooves 17, through which the flushing fluid emerges.
Conventional arrangements (not shown) are provided for rotating the spindle 4 and imparting reciprocatory axial motion to it and for imparting axial displacement to the expansion control rod 12.
The lapping tool hereinbefore described is used as follows:
At the start of the work, the thrust members 6 protrude farther than the thrust members 7 from the body 1 (FIG. 5). The sleeve 13 is thus subjected to irregular deformation, so that only its coarse-grained abrasive serrations 18 contact the walls of the bore that is to be honed. The roughing stage is then carried out, during which the mandrel 10 is moved in the direction of the arrow F, causing the thrust members 6 to move outwards and thus increasing the diameter of the segmented serrations 18 of the sleeve.
The thrust members 7, however, also move outwards, and more rapidly than the members 6 because of the difference in the gradients p1 and p2. By the time the roughing is almost complete, the thrust members 6 and 7 protrude equally from the body 1 and the sleeve 13 is circular (FIG. 6).
As the mandrel 10 continues to move, the thrust members 7 finally protrude beyond the members 6, so that now the sleeve contacts the walls of the bore only by its fine-grained abrasive serrated surfaces 19 and the finishing of the bore can proceed. (FIG. 7).
1. Field of the Invention
This invention relates to a tool for rough finishing and honing bores in workpieces.
2. Description of the Prior Art
In micro-machining or honing work, it is conventional for the workpiece bore to be initially rough finished with a first lapping tool that has coarse-grained abrasive faces and then to be finished with a second lapping tool having finer-grained abrasive faces which effected the required honing. It is therefore necessary either to use two separate lapping machines or alternatively to stop the single machine and replace one lapping tool by another.
An object of the present invention is to provide a combination lapping tool with which a bore can be rough finished and immediately honed without the need for stopping the machine.
SUMMARY OF THE INVENTION
According to the present invention there is provided in a lapping tool a hollow body, a plurality of first radially displaceable thrust members protruding from the body, each said first thrust member having a radially inner face inclined to the longitudinal center line of the body, a plurality of second radially displaceable thrust members protruding from the body, each said second thrust member having a radially inner face inclined to the longitudinal center line of the body by an angle greater than that of the first thrust members, an expandable split sleeve surrounding the thrust members and having first portions thereof coated with a relatively coarser abrasive and second portions coated with a relatively finer abrasive, an expander displaceable within the body and having two sets of surfaces, one set being inclined to the longitudinal axis of the body at an angle corresponding to the inclination of the first thrust members and the other set being inclined at an angle corresponding to the inclination of the second thrust members, the surfaces of said two sets being in contact with the corresponding inclined surfaces of the thrust members and the first portions of the sleeve lying radially outwardly of the first thrust members and the second portions of the sleeve lying radially outwardly of the second thrust members.
With this construction, any given axial displacement of the expander will result in greater radial displacement of the thrust members situated opposite the fine-grained surfaces.
At the start of the honing operation, the thrust members opposite the coarse-grained surfaces protrude farther than the others, so that only those surfaces are brought into play, enabling rough finishing to proceed. As the work progresses, the expander is displaced within the body by conventional means and causes radial displacement of the various thrust members. There comes a moment when the thrust members opposite the fine-grained surfaces protrude more than the others, so that, from that moment on, only these surfaces are in action, enabling the finishing stage to proceed.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of a lapping tool in accordance with the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:
FIG. 1 is an axial section of the lapping tool;
FIG. 2 is a cross-section on the line II--II of FIG. 1;
FIG. 3 is a side elevation of part of the tool;
FIG. 4 is a cross-section on the line IV--IV of FIG. 1; and
FIGS. 5 to 7 indicate diagrammatically the movements of thrust members forming parts of the tool, the amount of displacement having been exaggerated in the interest of clarity.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The combination lapping tool illustrated comprises a body 1, one end of which carries two lugs 1a, connected to an internal ring 2, by two coaxial pins or other members 3a; the ring 2 is in turn connected to two lugs 4a, on a drive spindle 4, by two pins or other coaxial members 3b, which have their common longitudinal center line at right angles to that of the pins 3a. Hence, the body 1 is constrained to rotate with the spindle 4, to which it is connected by the universal joint formed by the lugs 1a and 4a and the pins 3a and 3b.
The body 1 has longitudinal slots or other openings 5, in which thrust members 6 and 7 are received, the members 6 alternating with the members 7. These thrust members fit into longitudinal grooves 8 and 9 respectively, in a mandrel 10, which is movable in a longitudinal bore in the body 1. This mandrel 10 is connected by a pin 11 and other parts to an expansion control rod 12, which is movable axially within the spindle 4.
The base of the grooves 8 is inclined at a gradient, p1, of, for example, 1 percent, the inner or bottom face of the corresponding thrust members 6 being similarly inclined. Displacement of the mandrel 10 in the axial direction indicated by the arrow F (FIG. 1) will therefore result in radial outwards displacement of the thrust members 6.
In the same way, the base of the grooves 9 is inclined at a gradient p2, but this is greater than p1, being, for example, 1.5 percent, and the inner or bottom face of the thrust members 7 is similarly inclined. Displacement of the mandrel 10 in the direction of the arrow F will therefore result in radial outwards displacement of the thrust members 7, this displacement being greater than that of the members 6.
A honing sleeve 13, split axially at 14, is mounted under tension over the assembly of thrust members 6 and 7 and thus to bias these members into contact with the base of the grooves 8 and 9. In that opening 5 in the body 1 which immediately precedes the split 14, considered in the direction of rotation of the body 1, lies a thrust member 7a, which is similar to the thrust members 7 but carries two projections 15, which engage in openings 16, in the sleeve 13. The purpose of these projections is twofold; to rotate the sleeve 13 and to fix the angular position of the sleeve in relation to the thrust members 6 and 7, so as to prevent these thrust members from changing position in relation to the sleeve.
The periphery of the sleeve 13 has longitudinal grooves 17, each of which, when the sleeve is in position on the body, lies equidistant from one thrust member 6 and one thrust member 7. These grooves 17 divide the peripheral face of the sleeve into segments equal in number to the number of thrust members, each segment lying opposite one of these. The grooves constitute weakened zones and thus enable the sleeve to undergo limited deformation.
Those segments of the sleeve 13 which lie opposite thrust members 6 are serrated at 18 and coated with an abrasive substance, consisting, for example, of a diamond-charged compound. The segments 19 opposite thrust members 7 are likewise serrated and coated with an abrasive substance consisting, for example, of a diamond-charged compound, but this is finer-grained than that of the abrasive substance on serrations 18.
Apertures 20 are provided in the bases of the grooves 17, through which the flushing fluid emerges.
Conventional arrangements (not shown) are provided for rotating the spindle 4 and imparting reciprocatory axial motion to it and for imparting axial displacement to the expansion control rod 12.
The lapping tool hereinbefore described is used as follows:
At the start of the work, the thrust members 6 protrude farther than the thrust members 7 from the body 1 (FIG. 5). The sleeve 13 is thus subjected to irregular deformation, so that only its coarse-grained abrasive serrations 18 contact the walls of the bore that is to be honed. The roughing stage is then carried out, during which the mandrel 10 is moved in the direction of the arrow F, causing the thrust members 6 to move outwards and thus increasing the diameter of the segmented serrations 18 of the sleeve.
The thrust members 7, however, also move outwards, and more rapidly than the members 6 because of the difference in the gradients p1 and p2. By the time the roughing is almost complete, the thrust members 6 and 7 protrude equally from the body 1 and the sleeve 13 is circular (FIG. 6).
As the mandrel 10 continues to move, the thrust members 7 finally protrude beyond the members 6, so that now the sleeve contacts the walls of the bore only by its fine-grained abrasive serrated surfaces 19 and the finishing of the bore can proceed. (FIG. 7).