CA1265343A - Microfinishing apparatus and method - Google Patents
Microfinishing apparatus and methodInfo
- Publication number
- CA1265343A CA1265343A CA000475233A CA475233A CA1265343A CA 1265343 A CA1265343 A CA 1265343A CA 000475233 A CA000475233 A CA 000475233A CA 475233 A CA475233 A CA 475233A CA 1265343 A CA1265343 A CA 1265343A
- Authority
- CA
- Canada
- Prior art keywords
- workpiece
- insert
- rigid
- microfinishing
- tape
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
- B24B5/36—Single-purpose machines or devices
- B24B5/42—Single-purpose machines or devices for grinding crankshafts or crankpins
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B21/00—Machines or devices using grinding or polishing belts; Accessories therefor
- B24B21/02—Machines or devices using grinding or polishing belts; Accessories therefor for grinding rotationally symmetrical surfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B35/00—Machines or devices designed for superfinishing surfaces on work, i.e. by means of abrading blocks reciprocating with high frequency
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
- B24D3/001—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as supporting member
- B24D3/002—Flexible supporting members, e.g. paper, woven, plastic materials
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
- Grinding Of Cylindrical And Plane Surfaces (AREA)
- Polishing Bodies And Polishing Tools (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A microfinishing apparatus and method is disclosed particularly useful for microfinishing workpiece surfaces such as are found in journal bearings and cylinder bores. This invention improves over conventional machines and methods wherein coated abrasive tape is brought into contact with a relatively rotating workpiece surface and is pressed against that surface by an elastomeric plastic insert.
According to this invention, the insert is made from a relatively rigid substance such as honing material stone. Since the insert is made from a rigid material, the insert surface shape is generated in the workpiece surface and therefore geometry corrections in the workpiece surface can be accomplished. In alternate embodiments of this invention, the rigid inserts have relieved portions or noncylindrical surfaces such that a desired surface profile in the workpiece surface is generated. In another embodiment, one or more flexible inserts are added to the rigid insert enabling the fillet radius area to be microfinished. In yet another embodiment, coated abrasive tape includes a multiplicity of perforations thereby permitting the exchange of cutting fluids between the surfaces. Finally, several means for supporting the rigid inserts for slight rotation relative to the workpiece surface are described.
A microfinishing apparatus and method is disclosed particularly useful for microfinishing workpiece surfaces such as are found in journal bearings and cylinder bores. This invention improves over conventional machines and methods wherein coated abrasive tape is brought into contact with a relatively rotating workpiece surface and is pressed against that surface by an elastomeric plastic insert.
According to this invention, the insert is made from a relatively rigid substance such as honing material stone. Since the insert is made from a rigid material, the insert surface shape is generated in the workpiece surface and therefore geometry corrections in the workpiece surface can be accomplished. In alternate embodiments of this invention, the rigid inserts have relieved portions or noncylindrical surfaces such that a desired surface profile in the workpiece surface is generated. In another embodiment, one or more flexible inserts are added to the rigid insert enabling the fillet radius area to be microfinished. In yet another embodiment, coated abrasive tape includes a multiplicity of perforations thereby permitting the exchange of cutting fluids between the surfaces. Finally, several means for supporting the rigid inserts for slight rotation relative to the workpiece surface are described.
Description
~2~ 3 "~ IMPROV~D MICROFINIS~ING APPARATUS AN~ MET~OD
BAC~GROUND AND SU~M~RY QF T~F INYENTION
This invention relates to metal surface finishing and particularly to an improved apparatus and method for microfinishing meta] surfaces using coated abrasive tape materials.
Numerous types of machinery components must have finely controlled surface finishes in order to perform satisfactorily. For example, surface finish control, also referred to as microfinishing, is particularly significant in relation to the manufacturing of journal bearing and cam surfaces such as are found in internal combustion engine crankshafts, camshafts and power transmission shafts and other finished surfaces. For journal type bearings, very accurately formed surfaces are needed to provide the desired bearing effect which results when lubricant is forced between the journal and the associated bearing. Improperly finished bearing surfaces may lead to premature bearing failure and can limit the load carrying capacity of the bearing.
Currently, there is a demand for higher control of journal bearing surfaces by internal combustion engine manufactures as the result of; greater durability require-ments necessary to offer improved product warranties, the higher operating speeds at which engines (particularly in automobiles~ are now required to sustain, and the greater bearing loads imposed through increased efficiency of engine structures.
In addition to bearing structures, surface finish mls/lc~
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~26~i3~3 control must be provided for en8ine cylinder walls in order to provide the desired oil and gas seal with the piston rings. Numerous other types of machine components also require controlled surface finishes, particularly along areas of sliding contact between parts.
Microfinishing has primarily been accomplished according to prior art using several different types of machining techniques. In stone microfinishing, a stationary honing stone is brought against the desired surface. When microfinishing cylindrical journal bearing surfaces, the honing stone is caused to oscillate transversely from one edge of the journal to another as the workpiece is rotated with respect to the stone. This process possesses a number of significant disadvantages. Due to the requirement that the honing stone be soft enough to be self-dressing and to provide the desired material removal characteristics, the stone, through use, takes on the shape of the part being finished. Therefore, this method, instead of correcting ~ geometry variation~s in the part being microfinished, actually causes such var1ations to occur. AdditionDlly, 1~ since honing stones are perishable, they must be frequently ; ~replaced and~redressed. Finally, it is extremely difficu1t to find honing stones with consistent qualities resulting in significant differences in the~ finished parts when machined by different stones.
Anothe~r significa~nt~ dlsadvantag~e of stone microfinishing of jour;nal bearing~6~ ueing a honing stone is the fact that, since the journal~ generally include m~1s/1cm ~ 2 - ~ ~
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outwardly projecting radius edges, the stone cannot laterally overstroke portions of the surface being machined which leads to uneven stone wearing. Such uneven wearing causes a change in the profile shape of the honing stone, and this shape is consequently generated in subsequent parts being machined. Finally, since the honing stone generally has sharp corner edges, it cannot be used to microfinish near the radius edges of the bearing surface.
In another ~nown microfinishing process, herein referred to as conventional coated abrasive tape micro-finishing, the surface being finished is caused to rotate and a coated abrasive tape is brought into contact under pressure with this surface. As the part is rotated, the abrasive material reduces the roughness of the surface. In the conventiona] process, the tape is brought into contact with the rotating surface by pressure exerted by compressible elastomeric inserts, typically made from urethane plastic compounds. The cDnventional coated abrasive tape microfinishing process overcomes several of the disadvantages associated with stone microfinishi~g.
This process i~ capable of microfinishing in the journal fillet radius area since the tape is relatively flexible~
In addition, this process uses a renewable abrasive surface which can be purchased having consistent qualities. This process, however, does not overcome other disadvantages of s~tone mlcrofinishing, Principal among these disadvantages of this process ls the fact that the process does not cor-rect geo0etry variations in the part being microfinished, .
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since the insert backing the coated abrasive tape is a flexible material and therefore, the tape conforms to the surface profile of the component surface being machines.
In still another variation of microfinishing processes known to the prior art, a rigid insert is used to press abrasive coated paper or cloth material into contact with a relatively moving workpiece surface. Abrasive coated paper or cloth materials are, however, relatively thick and compressible, and therefore, this method did not enable significant workpiece geometry corrections since the paper or cloth would ~Igive9~ and conform to minute i~regularities in the workpiece surface.
In addition to the above-noted shortcomings according to the currently known microfinishing processes, great difficulty has been encountered in removing ferrite caps which are present on the Einished surfaces o~ nodular iron workpieces. These hard caps are present on the outside surface of the bearing and can lead t-o premature bearing failure.
In view of the above-described shortcomings of microfinishlng devices and methods according to the prior art, it is a principal object of this invention to provide a microfinishing apparatus and method which is capable of correcting geometry imperfections in finished surfaces. It is yet another object to consistently produce surfaces h~aving smoothness characteristics superi;or to those achievable by conventional means.
The above principal objects of this invention are mls/lcm - 4 -:~ .
', ~ . ' ~.
- ~ Ei53~3 provided by a microfinishing system which employs an abrasive coated tape which is brought into contact with a rotating workpiece, and is pressad into contact with that workpiece by a rigid precision formed backup insert. This rigid insert does not cause the abrasive tape to conform to the surface profile of the workpiece. Instead, the rigid insert causes greater abrasive tape contact pressure to be applied to portions of the workpiece surface which extend beyond the desired surface, thereby causing greater material removal in those areas. This system therefore permits the microfinishing system to correct geometry imperfections in the workpiece. In the practice of this invention, it is essential that the abrasive coated tape be made of a material which is relatively incompressible such that the tape will not conform to irregularities but instead will enable these irregularities to be removed. Since the insert is not the primary cutting tool, it is not subject to significant changes in profile with use. With appropriate additional components, the rigid inserts may be provided with the capability of polishing fillet radius areas. The microfinishing system according to this invention has been found to provide a significant advance in the art of microfinishing enabling consistent production of surface finishes unachievable using the devices and processes according to the teachings of the prior art.
In summaxy, therefore, the present invention may be broad~y considered as providing a method of microfinishing a workpiece an outside curved workpiece surface which comprises the steps of: rotating the workpiece; and causing a rigid shoe LCM:jj 5 ', . . .
~2~ 3 surface to contact and press a relatively incompressible abrasive coated tape against the workpiece surface, the rigid shoe surface having a predetermined shape related to the desired workpiece surface shape and defining an included angle between the boundaries of contact between the tape and the shoe oF greater than 120 and preferably about 160 relative to the center of the curved workpiece surface, whereby a desired workpiece surface shape is generated in the workpiece surface.
Furthermore, the above method may be carried out by way of a machine for microfinishing an outside curved surface of a workpiece, comprising: abrasive coated tape relatively incompressible; a shoe assembly having means for holding the tape and having a rigid surFace forming a predetermined surface shape related to a desired workpiece surface shape, the rigid surface contacting and pressing the tape into contact with the workpiece surface, the rigid surface defining an included angle between the boundaries of contact between the tape and the shoe of greater than 120 and preferably about 160 relative to the center of the curved workpiece surface; means for causing relative rotation between the workpiece and the shoe assembly, and an arm which supports the shoe assembly such that relative movement between the workpiece surface and the tape occurs as the workpiece is rotated relative to the shoe assembly.
Additional beneflts dnd ddvantages oF the present invention will become apparent to those skilled in the art to which this invention relates upon a reading of the -,~., .~
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3~3 described preferred embodiments of this invention taken in conjunction wi~h the accompanying drawings.
BRIEF DESCRIPTION OF T~E DRA~INGS
Figure 1 is a pictorial view of a crankshaft being rotated such that one of its pin journals is being micro-finished by the clamping of a polishing shoe assembly against the pin journal;
Figure 2 is a cross sectional view taken through a polishing shoe assembly according to the prior art;
Figure 3 is a cross-sectional view taken along line 3-3 of Figure 2;
Figure 4 is a cross-sectional view of a polishing shoe assembly according to the subject invention;
Figure 5 is a cross-sectional view taken along line 5-5 of Figure 4;
Figure 6 is a second embodiment of thi9 invention employing a rigid back-up insert having relieved portions;
Figure 7 i9 a cross-sectional view taken along line 7-7 of Figure 6;
- - :
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~Si3~3 Figure 8 shcws a.third en~odi~ent of ~is invention using a n~difi~d rigid back-up insert;
Figure 9 is a cross-sectional view taken along line 9-9 of Figure 8;
Fisure 10 illustrates a fourth embcdim, nt of this m~ention wherein a rigid back-up m sert is used with flexible inse~s such that the fillet radius portions may be ~iclofinished;
Figure 11 shows a fifth embldiment of this invention wh~ein sslid back-up inserts are used in conjunction ~ith a perforated coated abrasive tape which enhanoes lubricant flow to the surfa oe being microfinished;
Figure 12 shows a sixth embodlment of ~his in~ention w~erein an alternate %eans of mounting the polishing shoe as~embly is shown;
Figure 13 s ~ s a seventh emboslment of this invention wherein an elastomeric insert is pxovided to polish the filet radius and side wall portions of a workpiece; and Figure 14 is a cross-sectional view taken along l me 14-14 of Figure 13 particularly shcwing the elastomeric ~sert acoo ~ g to this embodiment of the inventionO
D ~ DESCRIPTICN OF T9E DR~WINGS
. ~ . .... -- .
A polishing sh~e asse~bl~ is shown by Figure 1 and is designated there by referen oe character 10. Pvlishing sh oe asse~bly 10 is shcwn with the associated support mechanisms shcwn schematically and is shown in position to microfini.sh a bearing surface of an in ~
o~mbustion ~ngine crankshaft. As is shown by that ~igure, cranksha~t 12 is supported at opposing ends ky hRadstock 14 and tailsbock 16 which to~e~her cause the cr~nhshaft to be rotated abcut it~s longitudinal oenter axis. Crankshaft 12 includes a plurality of cylindri~al bearing ~ur~aces which nust ~e microfinished including p m bearings 18 which, in use, becon~s ccnnected to a piston connecting rod, and m~in k~arings 20, :
", , .`' ,.' . ' ' ~ ~ ' .: .: : ~ ~ ,: , , ., . ., : .
3~3 which support the crankshaft for rotation within the en~ine block.
Polishing shoe as.~embly 10 is sh~n nc~nte~ to arm 22. Polishing shoe assembly 10 is caused to oscillate laterally along the surface being ~achined by oscillating the shoe assembly, or by oscillating the workpiece relative to the shoe assemhly. Arm 2~ permits polishing shoe assembly 10 to orbit ~ith pin bearing 18 since that beari~g jcurnal is positioned eccentrically with respect to the oenter of rotation of crankshaft main bearings 20.
With particular referen oe to Figure 2, a polishing shoe asse~bly according to the prior art is illustrated. Pblishing shoe assembly lO inclu~es two h~lves, upper shoe 32 and lcwer shoe 34 ~shcwn partially in p~antom lines). me~e halves are each connected to a support structure which may include hydraulic or pneumatic biasmg cylinders acting on ~12 shce halves (as shawn in Fhantcm lines in Figure
BAC~GROUND AND SU~M~RY QF T~F INYENTION
This invention relates to metal surface finishing and particularly to an improved apparatus and method for microfinishing meta] surfaces using coated abrasive tape materials.
Numerous types of machinery components must have finely controlled surface finishes in order to perform satisfactorily. For example, surface finish control, also referred to as microfinishing, is particularly significant in relation to the manufacturing of journal bearing and cam surfaces such as are found in internal combustion engine crankshafts, camshafts and power transmission shafts and other finished surfaces. For journal type bearings, very accurately formed surfaces are needed to provide the desired bearing effect which results when lubricant is forced between the journal and the associated bearing. Improperly finished bearing surfaces may lead to premature bearing failure and can limit the load carrying capacity of the bearing.
Currently, there is a demand for higher control of journal bearing surfaces by internal combustion engine manufactures as the result of; greater durability require-ments necessary to offer improved product warranties, the higher operating speeds at which engines (particularly in automobiles~ are now required to sustain, and the greater bearing loads imposed through increased efficiency of engine structures.
In addition to bearing structures, surface finish mls/lc~
.. . . ~ . . -.. ..
'.
:-, . .~ - . .. ,. . :
~ .
,:, ~ " ~
~26~i3~3 control must be provided for en8ine cylinder walls in order to provide the desired oil and gas seal with the piston rings. Numerous other types of machine components also require controlled surface finishes, particularly along areas of sliding contact between parts.
Microfinishing has primarily been accomplished according to prior art using several different types of machining techniques. In stone microfinishing, a stationary honing stone is brought against the desired surface. When microfinishing cylindrical journal bearing surfaces, the honing stone is caused to oscillate transversely from one edge of the journal to another as the workpiece is rotated with respect to the stone. This process possesses a number of significant disadvantages. Due to the requirement that the honing stone be soft enough to be self-dressing and to provide the desired material removal characteristics, the stone, through use, takes on the shape of the part being finished. Therefore, this method, instead of correcting ~ geometry variation~s in the part being microfinished, actually causes such var1ations to occur. AdditionDlly, 1~ since honing stones are perishable, they must be frequently ; ~replaced and~redressed. Finally, it is extremely difficu1t to find honing stones with consistent qualities resulting in significant differences in the~ finished parts when machined by different stones.
Anothe~r significa~nt~ dlsadvantag~e of stone microfinishing of jour;nal bearing~6~ ueing a honing stone is the fact that, since the journal~ generally include m~1s/1cm ~ 2 - ~ ~
,. .
.....
.. . ... . ~ . .. . .. ~ . . .
i3~
outwardly projecting radius edges, the stone cannot laterally overstroke portions of the surface being machined which leads to uneven stone wearing. Such uneven wearing causes a change in the profile shape of the honing stone, and this shape is consequently generated in subsequent parts being machined. Finally, since the honing stone generally has sharp corner edges, it cannot be used to microfinish near the radius edges of the bearing surface.
In another ~nown microfinishing process, herein referred to as conventional coated abrasive tape micro-finishing, the surface being finished is caused to rotate and a coated abrasive tape is brought into contact under pressure with this surface. As the part is rotated, the abrasive material reduces the roughness of the surface. In the conventiona] process, the tape is brought into contact with the rotating surface by pressure exerted by compressible elastomeric inserts, typically made from urethane plastic compounds. The cDnventional coated abrasive tape microfinishing process overcomes several of the disadvantages associated with stone microfinishi~g.
This process i~ capable of microfinishing in the journal fillet radius area since the tape is relatively flexible~
In addition, this process uses a renewable abrasive surface which can be purchased having consistent qualities. This process, however, does not overcome other disadvantages of s~tone mlcrofinishing, Principal among these disadvantages of this process ls the fact that the process does not cor-rect geo0etry variations in the part being microfinished, .
~ mlsjlc0 - 3 -" , , ................ ;. ,: .: . ., '' - :- ~' ~
since the insert backing the coated abrasive tape is a flexible material and therefore, the tape conforms to the surface profile of the component surface being machines.
In still another variation of microfinishing processes known to the prior art, a rigid insert is used to press abrasive coated paper or cloth material into contact with a relatively moving workpiece surface. Abrasive coated paper or cloth materials are, however, relatively thick and compressible, and therefore, this method did not enable significant workpiece geometry corrections since the paper or cloth would ~Igive9~ and conform to minute i~regularities in the workpiece surface.
In addition to the above-noted shortcomings according to the currently known microfinishing processes, great difficulty has been encountered in removing ferrite caps which are present on the Einished surfaces o~ nodular iron workpieces. These hard caps are present on the outside surface of the bearing and can lead t-o premature bearing failure.
In view of the above-described shortcomings of microfinishlng devices and methods according to the prior art, it is a principal object of this invention to provide a microfinishing apparatus and method which is capable of correcting geometry imperfections in finished surfaces. It is yet another object to consistently produce surfaces h~aving smoothness characteristics superi;or to those achievable by conventional means.
The above principal objects of this invention are mls/lcm - 4 -:~ .
', ~ . ' ~.
- ~ Ei53~3 provided by a microfinishing system which employs an abrasive coated tape which is brought into contact with a rotating workpiece, and is pressad into contact with that workpiece by a rigid precision formed backup insert. This rigid insert does not cause the abrasive tape to conform to the surface profile of the workpiece. Instead, the rigid insert causes greater abrasive tape contact pressure to be applied to portions of the workpiece surface which extend beyond the desired surface, thereby causing greater material removal in those areas. This system therefore permits the microfinishing system to correct geometry imperfections in the workpiece. In the practice of this invention, it is essential that the abrasive coated tape be made of a material which is relatively incompressible such that the tape will not conform to irregularities but instead will enable these irregularities to be removed. Since the insert is not the primary cutting tool, it is not subject to significant changes in profile with use. With appropriate additional components, the rigid inserts may be provided with the capability of polishing fillet radius areas. The microfinishing system according to this invention has been found to provide a significant advance in the art of microfinishing enabling consistent production of surface finishes unachievable using the devices and processes according to the teachings of the prior art.
In summaxy, therefore, the present invention may be broad~y considered as providing a method of microfinishing a workpiece an outside curved workpiece surface which comprises the steps of: rotating the workpiece; and causing a rigid shoe LCM:jj 5 ', . . .
~2~ 3 surface to contact and press a relatively incompressible abrasive coated tape against the workpiece surface, the rigid shoe surface having a predetermined shape related to the desired workpiece surface shape and defining an included angle between the boundaries of contact between the tape and the shoe oF greater than 120 and preferably about 160 relative to the center of the curved workpiece surface, whereby a desired workpiece surface shape is generated in the workpiece surface.
Furthermore, the above method may be carried out by way of a machine for microfinishing an outside curved surface of a workpiece, comprising: abrasive coated tape relatively incompressible; a shoe assembly having means for holding the tape and having a rigid surFace forming a predetermined surface shape related to a desired workpiece surface shape, the rigid surface contacting and pressing the tape into contact with the workpiece surface, the rigid surface defining an included angle between the boundaries of contact between the tape and the shoe of greater than 120 and preferably about 160 relative to the center of the curved workpiece surface; means for causing relative rotation between the workpiece and the shoe assembly, and an arm which supports the shoe assembly such that relative movement between the workpiece surface and the tape occurs as the workpiece is rotated relative to the shoe assembly.
Additional beneflts dnd ddvantages oF the present invention will become apparent to those skilled in the art to which this invention relates upon a reading of the -,~., .~
.. . sd/~' 5a .. ".", .. .
,. ,.. :.. , ~. : ..
,', ~ . .
.~, .
3~3 described preferred embodiments of this invention taken in conjunction wi~h the accompanying drawings.
BRIEF DESCRIPTION OF T~E DRA~INGS
Figure 1 is a pictorial view of a crankshaft being rotated such that one of its pin journals is being micro-finished by the clamping of a polishing shoe assembly against the pin journal;
Figure 2 is a cross sectional view taken through a polishing shoe assembly according to the prior art;
Figure 3 is a cross-sectional view taken along line 3-3 of Figure 2;
Figure 4 is a cross-sectional view of a polishing shoe assembly according to the subject invention;
Figure 5 is a cross-sectional view taken along line 5-5 of Figure 4;
Figure 6 is a second embodiment of thi9 invention employing a rigid back-up insert having relieved portions;
Figure 7 i9 a cross-sectional view taken along line 7-7 of Figure 6;
- - :
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;~
~ mls/lcm : - 6 -~ ~ A
...... . ..
: ~ : . . ,,, . ~ " . ~.
.
..
- .: ,.
.. ~ ~ . .
.:
~Si3~3 Figure 8 shcws a.third en~odi~ent of ~is invention using a n~difi~d rigid back-up insert;
Figure 9 is a cross-sectional view taken along line 9-9 of Figure 8;
Fisure 10 illustrates a fourth embcdim, nt of this m~ention wherein a rigid back-up m sert is used with flexible inse~s such that the fillet radius portions may be ~iclofinished;
Figure 11 shows a fifth embldiment of this invention wh~ein sslid back-up inserts are used in conjunction ~ith a perforated coated abrasive tape which enhanoes lubricant flow to the surfa oe being microfinished;
Figure 12 shows a sixth embodlment of ~his in~ention w~erein an alternate %eans of mounting the polishing shoe as~embly is shown;
Figure 13 s ~ s a seventh emboslment of this invention wherein an elastomeric insert is pxovided to polish the filet radius and side wall portions of a workpiece; and Figure 14 is a cross-sectional view taken along l me 14-14 of Figure 13 particularly shcwing the elastomeric ~sert acoo ~ g to this embodiment of the inventionO
D ~ DESCRIPTICN OF T9E DR~WINGS
. ~ . .... -- .
A polishing sh~e asse~bl~ is shown by Figure 1 and is designated there by referen oe character 10. Pvlishing sh oe asse~bly 10 is shcwn with the associated support mechanisms shcwn schematically and is shown in position to microfini.sh a bearing surface of an in ~
o~mbustion ~ngine crankshaft. As is shown by that ~igure, cranksha~t 12 is supported at opposing ends ky hRadstock 14 and tailsbock 16 which to~e~her cause the cr~nhshaft to be rotated abcut it~s longitudinal oenter axis. Crankshaft 12 includes a plurality of cylindri~al bearing ~ur~aces which nust ~e microfinished including p m bearings 18 which, in use, becon~s ccnnected to a piston connecting rod, and m~in k~arings 20, :
", , .`' ,.' . ' ' ~ ~ ' .: .: : ~ ~ ,: , , ., . ., : .
3~3 which support the crankshaft for rotation within the en~ine block.
Polishing shoe as.~embly 10 is sh~n nc~nte~ to arm 22. Polishing shoe assembly 10 is caused to oscillate laterally along the surface being ~achined by oscillating the shoe assembly, or by oscillating the workpiece relative to the shoe assemhly. Arm 2~ permits polishing shoe assembly 10 to orbit ~ith pin bearing 18 since that beari~g jcurnal is positioned eccentrically with respect to the oenter of rotation of crankshaft main bearings 20.
With particular referen oe to Figure 2, a polishing shoe asse~bly according to the prior art is illustrated. Pblishing shoe assembly lO inclu~es two h~lves, upper shoe 32 and lcwer shoe 34 ~shcwn partially in p~antom lines). me~e halves are each connected to a support structure which may include hydraulic or pneumatic biasmg cylinders acting on ~12 shce halves (as shawn in Fhantcm lines in Figure
2~ or ~ay be supported by a scissors type linkage device. This polishing shoe as~erbly e~plcys a semicircular surface 24 having a plurality of spaced dovetail-shaped grooves ~6. Within dovetail grooves 26 are ins*alled cccperatively shaped urethane insexts ,28. These inse~ s, dl~e to the mat~xial frnm which they are made, are oo~paratively flexible and cc~pressible, having a Durometer hardness of 90 ox less.
Each of the shoe portions include means for engaging coated abrasive tape 30 which is brought into co~pressive contact with the surface of pin beaxing 18. At the conclusion of the microfinishing cperation of one pin bearing 18, upper and lower shoes 32 and 34 are caused to separate ana are repositioned and clamped ontD another pin bearing 18 or a main bearing 20. Alternatively, a plurality of polishing shoe assemblies ~ay be provided such that the entire w~rkpiece may ba machined in one cperation. Sim~ltaneous with shce di~sengagement and re-engagement is an index ~ of tape 30 such that a predetermlned l~n of new abrasive material is brought in~o sh oe assembly 10. ~liS
indexing results in ~he abrasi~e ~urface being oonstantly renewed.
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i3~3 Figure 3 illustrates a cross-sectional view taken through Figure 2 and shows contact between insert 28 and pin bearing 18. Insert 28 is caused to traverse relative to the surface of pin bearing 18 as indicated by arrow A. Insert 28, being made of a flexible material, is caused to conform to the existing surface profile of pin bearing 18. There-fore, if imperfections such as waviness7 taper, convexness or concavity of the bearing surface exist, coated abrasive tape 30 will be caused to conform ~o the incorrect shape.
As a result, this prior art microfinishing method does not correct geometry imperfections in the parts being microfinished.
Figure 4 shows polishing shoe assembly 60 according to a first embodiment of this invention.
Polishing shoe assembly 60 includes upper shoe 62 and lower shoe 64. Polishing shoe assembly 60 varies principally from shoe assembly 10 shown by Figures 2 and 3 in that urethane inserts 28 are replaced with stone inserts 36. These~
inserts-are preferably made from honing stone material.
~; 20 Stones inserts 36 are characterized in that they are relatively non-deformable having a Durometer hardness greater than 90, yet are easily machined and provide a degree of frictional engagement with coated abrasive tape 30. Each of stone inserts 36 is mounted to a holder 38.
Stone inserts 36 and holders 38 are preferably permitted to "float" slightly ~ith`;respect to the upper a~d lower shoes, enabling them to rotate slightly as indicted by arrow B in Figure 5. Such relative rotation is provided according to : : .
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...
Si3~ ~
this embodiment by mounting holders 38 using mounting pins 40. Like shoe assembly 10, coated abrasive tape 30 is supported by shoes 62 and 64 such that when they engage pin bearing surface 18, the tape is brought into contact with the surface being microfinished.
c ;~ ~.L
C The p-~i~6~ advantages of the configuration of polishing shoe assembly 60 are best explained with reference to Figure 5. Stone insert 36 is provided which presents a surface having a predetermined curvature which is rigid and which exerts a compressive load on tape 30 against pin bearing 18. Since stone inserts 36 are rigid and relatively non-conformable, surface waviness, taper, convexity and concavity of the surface of pin bearing 18 are corrected since, in these instances, non-conforming portions of the surface of pin bearing 18 will be brought under greater contact pressures against coated abrasive tape 30, and therefore, more material will be removed in those areas until pin bearing 18 assumes the desired surface profile.
coated abrasive tape 30 ls preferably made of a polymeric plastic film material which is relatively incompress1ble.
Polyester films made ~rom polyethylene terephthalate such as MYLAR (a trademark of EI du Pont de Nemours Co.) have been found satisfactory due to their relatively low compressibility. The thickness of tape 30 is preferably in a range of between 2 and 8 mills. The co~bined rigidity or lack of compressibility of insert 36 and tape 30 insures that imperfections in the workpiece will be removed.
Abrasive coated paper or cloth products are generally mls/lcm - 10 -:~ . `. :
- . .
:: :
-- ........... .
., ~.
, : ;. ~: . -~2~i3~
unsuitable for use in connection with this invention since they are relatively compressible as compared to polymeric plastic tape materials of the type descrlbed above.
Additionally, the grit size of abrasive coated papers is generally not as uniform as that of abrasive coated polymeric plastic tape materials. As with the prior art devices, insert 36 and shoe assembly 60 are caused to oscillate relative to pin bearing 18 as the bearing is rotated relative to the shoe assembly, as indicated by arrow A in figure 5. Such lateral movement is achieved by moving the workpiece relative to polishing shoe assembly 62, or by moving the polishing shoe assembly relative to the workp;ece, or a combina~ion of both. When relative lateral movement is initiated, frictional engagement between stone insert 36 and coated abrasive tape 30 is necessary in order to urge the tape to move laterally, For this reason, hard materials having a very smooth surface such as machined metals are generally unsuitable for insert 36, unless they are sufficiently roughened to frictionally engage the back of coated tape 30. Materials which have been found suitable for insert 36 are conventional honing stone materials.
These materials exhibit the desired hardness and frictional characteristics and have been found to produce excellent results.
Now with partlcular reference to Figure 4, another feature in accordance with this invention will be described.
Angle C, shown in Figure 4, designates the maximu~ range of the point of contacts of the shoes 36 within either of the mls/lcm ~'.
~, -., "~ :
.. . . ..
~2~3~
shoes 62 or 64. The inventors have found that Angle C
should be at least 120 and preferably about 160 to provide improvements in terms of part geometry correction and rate of material removal as compared with shoes having a lesser range of angular contact. Improvements in part geometry correction are believed attributable to the fact that, with a larger angle of contact (Angle C), the shoes more closely approximate a cylinder themselves and therefore force the workpiece to assume such a configuration. The increase in material removal rate is believed attributable to a wedging effect wherein the contact pressures existing at the outer ranges of contact of the shoe are greater.
During the course of development of this inven-tion, the inventors further discovered that the rate of lateral oscillation of upper and lower shoes 6Z and 64 was lmportant in terms of producing the desired machining ac-tion. The shoes 62 and 64 are oscillated laterally while the workpiece is rotated ~or the workpiece may be moved laterally while the shoes are stationary). Abrasive coated tape 30 causes a cross hatched pattern to be developed on ~ the workpiece surface. These cross hatch patterns can be defined by lines which coincide with the direction of rela-tive motion between the workpiece and abrasive coated tape 30 as best shown in Figure 5. Cross latch angle is a function of the rate~s of w~orkpiece rotation and shoe oscil-lation and workpiece surface diameter. The inventors have f,ound that the cross hatch angle defined by Angle D, must exceed 2 in the area of the longitudinal center of the mls/lcm - 12 -: " . , ~, , ~.
..: . . ...
. .. ...
~: : . ,., ~ : :
.
bearing in order to provide acceptable finish quality and bearing performance. This cross hatch angle (Angle D) is somewhat greater than tha-t according to prior art machines and methods and contributes toward improving the quality of bearin8 surfaces generated~
~ odern day crankshafts are often made from nodular iron which has imbedded ferrite nodules. These nodules present themselves as caps on the bearing surface which should be removed in order to provide the desired bearing characteristics. During the course of development of this invention, it was discovered that removal of these ferrite caps was possible by first rotating the workpiece in one direction and then rotating the workpiece in the opposite direction. This process is believed effective since the minute abrasive grains on tape 30 become smoothened on one side, yet remain sharp on the other side, and reversing rotation permits the sharp grain sides to also remove material.
Other types of coated abrasive tape material 30 could be employed in connection with this invention. For example, a metal backed tape which is coated with abrasive material could also be used. However, it is essential that ~tape material 30 be relatively incompressible.
~ ~ ' , ~ mls/lcm - 13 -.
~ :
39~3 Figures 6 and 7 illustrate a second embodiment according to this invention. For this enbodiment~ portions of insert 136 are partially relieved such that they do not cause high contact ~xessure between coated abrasive tape 30 and pin bearing 18~ Figure 6 shcws a pair of opposed relief portions 142 which ar~ defined by arcuate borders 144. The surface of pin bearing 18 mcves with respect t~ inSert 136 in the direction indicated by arrow C. This seaxnd en}rdiment ~auses greater abrasive ~s Prial remcval ta occur at the separated ends of the surfa oe of pin b~aring 180 This second embodimEnt thexe~ore tends to cause the pin bearing ~urfaoe to assume a slightly ~arrel shaped con~iguration, such that its diame~ers at each end are slightly less than the diametex at the oenber. Such ~barrelling" is sameti~es desirable bo achieve optimal bearing surfaces.
A third emboiiment according bo this inwention is æhnwn wQth reference to Figures 8 and 9. Ihis embsdimen~ also p~oes a slightly barrel shap~d journal bearing surfaoe but achieves this result in a differ~t manner than that according to Figures 6 and 7. A Ir~dified cylindrical c~ntour in insert 23S is pro~ce~l 50 that the I:adiUs of ffle ved ~s~t surface at po~?ts ~ ends l~f the ja:n~al bear~ng is less than at the oenter of the j~urnal bearing. As sl~;n by Figure 8, relative m ~ nt of pin bearing 18 w1th respect to insert 236 occurs along the direction indicated by arrow C. As illustrated ~7 Figure 9, portions of the surfa oe of insert 236 near the lateral edges are designated ~y reference characber 254 and have a radius of ~urvature some~hat less than that of central shoe 6eg~ent 256 (these differences ~n radius are exaggerated in Figure 9 for illustration p~rposesJ. This embodlment, therefore, provides another ~ s for generating a nan-cylindrical sur~aoe and a workpiece being ~achined. According to sh~"~7 ~;7q this en~rdiment, such ~ results from ~achining the desired sur~aoe contour directly into stone insert 236 and this cont~ur will be Impressed and ~achined in the c~rresponding workpiece.
: AL ~Y
~2~ 3 A ~ourth enbcdm ent of this inventi~l is illustrated by Figure 10, w~ich ena~les the side wall portion 68 of p m bearing 18 to be //e 7~
finished and f~Ither permits any burrs existing betweeni~k~ radius 46 and the bearing surface to be re~oved~ In accordan oe with this enbodinent, flexible inserts 348 and 350 are prcvided with inserts 36.
~ ~se flexible inserts exert a ccmpressive foroe against coa~ed abrasive tape 30 when the inserts are brought to their ex*reme la~eral positicns.
Although ~he e~ployment of a flexible m~terial for inserts 348 and 350 results in the same shortoomings associated with conventional processes, it is generally not necessary to highly cQntrol the profile shape of these surfa oe s. Sin oe it is neoessary for tape 30 to flex to a considerable extent when brought into contact with side wall portion 68, it is sometimes necessary to provide edge cuts within the ooated tape, according to principles ~ncwn to the prior art. U æ of inserts 348 and 350 further pe~mats the elimination of burrs or sharp edges which may exist at the edges 51 of the ~earing surface o jouxnal 18 when the fillet radius are cut deep into the workpiece ~as shcwn by Figure 10).
By ~cunting inserts 348 and 350 such that they exert a slight compressive load cn the surfac~ of bearLng 1~, t~pe 30 is caused tD
remove such burrs when the insert forces the tape into the fillet.
Figure 11 illustrates a fifth emtodlment according to this inventicn. T~is enbcdlm~nt employs inserts 36 and ~ and lower sho s 62 and 64 as aescribed in cOnneCtiQn with Figure 4. Ihis embodiment differs from the previously described enbodinents in that coated abrasive~tape 430 is used which has a multiplicity of perforations 452 along its lensth. Perfo~ations 452 enable lubricants or cutting fluids to come in contact wi*h the surfaoe s being ~achinedO ~low of lubricant or cutting fluids to the workpiece is oonducted thr3ugh passage 70 pper and lcwer shoes 62 and 64.
A sixth emkcc~nent according ~o this invention is described wqth referen oe to ~igure 12~ As shcwn ~y that Figure, lower shce 56~ is ..~
~' ` ` :'' ,.: "'' .:' ' ` :
. :; :: ' ' ; :
. .
~Si3~3 ~ounted within cradle 566 by a mounting pin 540. These ~ wnting pins p~ it rotation of lower shoe assem~ly 564 with respect to cradle 566.
A similar ~ounting arrangement would also be prc~Tided for upper shoe as~embly 562 Inot shcwn). This arrange~.ent pruvides the desir~ble "floatingl' characteristic as describ~ed with referen oe to ~igure 4 ~herein individual mounting pins 40 are provided for e~ch of the inserts 36, The c.~nstruction illustrated ~y Figure 12 has the primary adTantage of being simpler t~ construct. In operation, this em~o~i~ent performs as described in connection ~ith the earlier described en}odlmEnks.
A seventh em~odime~t according to this invention is shown by Figures 13 and 14. This embodiment prGvides another means of finishing the side wall portions 68 of a bearing 18 or 20. In accordance with this emkodimen~, upper sh oe 62 and/or lower shoe 64 include elastomeric insert 6~2 which is employed to polish the side wall portions 68. As shcwn by Figure 13, upper shce 62 and lcwer shoe 64 are constructed identical to that described with reference to Figure 4 except that one or more of stone inserts 36 is rep-~ced by elastomeric insert 672.
Elastomeric insert 672 is particularly shcwn in detail by Figure 14. As s~cw~ ~y that Figure, insert 672 is ~a~e from an elastoo~ric substance su:~h as a urethane compo~md and includes radiused edge sur~aces 674 and 676. Insert 672 has a lateral width which exceeds that of stone inserts 36 such that as polishing shoe assembly 60 is stroked laterallyj radiused side surfaces 674 and 676 cause ooate~ abrasive tape 30 to contact si~e wall portions 68, thereby microfinishing that area.
Preferably, elastcmeric insert 672 is resiliently biased within the associated shoe Ecrtion, enabl mg it to m~ve radially and laterally with respect to the associated bearing surface. AS sho~n ~y Figure 14, ldteral co~pliance of elasbomeric insert 672 is provided ~y e~ploying drill rcd 678~which flexes, enabling the insert ~o ~ve laterally with respect bo upp~r shoe ~2. Ihe :aximum extent of lateral compliance i5 limited by oontact between elastcmeric insert 672 and insert holder 682.
~adial compliance or insert 672 is provided ~ ~mploying helica~ coil fipring 680 w~ich exerts a dswnward oompressi~e ~oroe upo~ coat~d ~2~ 3~3 abrasive tape 300 The maxi~um extent of radial displaoement is controlled by the position o~ head 684 on drill m d 678. This ~bcdiment provides another nEans of gaining the advantages of a rigid insert in accordance with this invention and furthex finishing the side wall and radius portions of the bearing surface being micrDfinished.
~ hile the abcve descripticn oonstitutes the -prefeIred enbodiments of the present invention, it will be cçprecia~ed that the in~ention is sus oe ptible to m~dification, variati~n. and change wi~hout departing from the proper scope and fair meaning of the acoo~pany mg claIms, `
, ' `': .
Each of the shoe portions include means for engaging coated abrasive tape 30 which is brought into co~pressive contact with the surface of pin beaxing 18. At the conclusion of the microfinishing cperation of one pin bearing 18, upper and lower shoes 32 and 34 are caused to separate ana are repositioned and clamped ontD another pin bearing 18 or a main bearing 20. Alternatively, a plurality of polishing shoe assemblies ~ay be provided such that the entire w~rkpiece may ba machined in one cperation. Sim~ltaneous with shce di~sengagement and re-engagement is an index ~ of tape 30 such that a predetermlned l~n of new abrasive material is brought in~o sh oe assembly 10. ~liS
indexing results in ~he abrasi~e ~urface being oonstantly renewed.
:i:
~', '' .
, .
'' '. ~ ' :
~, :
i3~3 Figure 3 illustrates a cross-sectional view taken through Figure 2 and shows contact between insert 28 and pin bearing 18. Insert 28 is caused to traverse relative to the surface of pin bearing 18 as indicated by arrow A. Insert 28, being made of a flexible material, is caused to conform to the existing surface profile of pin bearing 18. There-fore, if imperfections such as waviness7 taper, convexness or concavity of the bearing surface exist, coated abrasive tape 30 will be caused to conform ~o the incorrect shape.
As a result, this prior art microfinishing method does not correct geometry imperfections in the parts being microfinished.
Figure 4 shows polishing shoe assembly 60 according to a first embodiment of this invention.
Polishing shoe assembly 60 includes upper shoe 62 and lower shoe 64. Polishing shoe assembly 60 varies principally from shoe assembly 10 shown by Figures 2 and 3 in that urethane inserts 28 are replaced with stone inserts 36. These~
inserts-are preferably made from honing stone material.
~; 20 Stones inserts 36 are characterized in that they are relatively non-deformable having a Durometer hardness greater than 90, yet are easily machined and provide a degree of frictional engagement with coated abrasive tape 30. Each of stone inserts 36 is mounted to a holder 38.
Stone inserts 36 and holders 38 are preferably permitted to "float" slightly ~ith`;respect to the upper a~d lower shoes, enabling them to rotate slightly as indicted by arrow B in Figure 5. Such relative rotation is provided according to : : .
mlstlcm _ g _ : ~
: ~, : . ., .. . ~, .. -.. ....
...
Si3~ ~
this embodiment by mounting holders 38 using mounting pins 40. Like shoe assembly 10, coated abrasive tape 30 is supported by shoes 62 and 64 such that when they engage pin bearing surface 18, the tape is brought into contact with the surface being microfinished.
c ;~ ~.L
C The p-~i~6~ advantages of the configuration of polishing shoe assembly 60 are best explained with reference to Figure 5. Stone insert 36 is provided which presents a surface having a predetermined curvature which is rigid and which exerts a compressive load on tape 30 against pin bearing 18. Since stone inserts 36 are rigid and relatively non-conformable, surface waviness, taper, convexity and concavity of the surface of pin bearing 18 are corrected since, in these instances, non-conforming portions of the surface of pin bearing 18 will be brought under greater contact pressures against coated abrasive tape 30, and therefore, more material will be removed in those areas until pin bearing 18 assumes the desired surface profile.
coated abrasive tape 30 ls preferably made of a polymeric plastic film material which is relatively incompress1ble.
Polyester films made ~rom polyethylene terephthalate such as MYLAR (a trademark of EI du Pont de Nemours Co.) have been found satisfactory due to their relatively low compressibility. The thickness of tape 30 is preferably in a range of between 2 and 8 mills. The co~bined rigidity or lack of compressibility of insert 36 and tape 30 insures that imperfections in the workpiece will be removed.
Abrasive coated paper or cloth products are generally mls/lcm - 10 -:~ . `. :
- . .
:: :
-- ........... .
., ~.
, : ;. ~: . -~2~i3~
unsuitable for use in connection with this invention since they are relatively compressible as compared to polymeric plastic tape materials of the type descrlbed above.
Additionally, the grit size of abrasive coated papers is generally not as uniform as that of abrasive coated polymeric plastic tape materials. As with the prior art devices, insert 36 and shoe assembly 60 are caused to oscillate relative to pin bearing 18 as the bearing is rotated relative to the shoe assembly, as indicated by arrow A in figure 5. Such lateral movement is achieved by moving the workpiece relative to polishing shoe assembly 62, or by moving the polishing shoe assembly relative to the workp;ece, or a combina~ion of both. When relative lateral movement is initiated, frictional engagement between stone insert 36 and coated abrasive tape 30 is necessary in order to urge the tape to move laterally, For this reason, hard materials having a very smooth surface such as machined metals are generally unsuitable for insert 36, unless they are sufficiently roughened to frictionally engage the back of coated tape 30. Materials which have been found suitable for insert 36 are conventional honing stone materials.
These materials exhibit the desired hardness and frictional characteristics and have been found to produce excellent results.
Now with partlcular reference to Figure 4, another feature in accordance with this invention will be described.
Angle C, shown in Figure 4, designates the maximu~ range of the point of contacts of the shoes 36 within either of the mls/lcm ~'.
~, -., "~ :
.. . . ..
~2~3~
shoes 62 or 64. The inventors have found that Angle C
should be at least 120 and preferably about 160 to provide improvements in terms of part geometry correction and rate of material removal as compared with shoes having a lesser range of angular contact. Improvements in part geometry correction are believed attributable to the fact that, with a larger angle of contact (Angle C), the shoes more closely approximate a cylinder themselves and therefore force the workpiece to assume such a configuration. The increase in material removal rate is believed attributable to a wedging effect wherein the contact pressures existing at the outer ranges of contact of the shoe are greater.
During the course of development of this inven-tion, the inventors further discovered that the rate of lateral oscillation of upper and lower shoes 6Z and 64 was lmportant in terms of producing the desired machining ac-tion. The shoes 62 and 64 are oscillated laterally while the workpiece is rotated ~or the workpiece may be moved laterally while the shoes are stationary). Abrasive coated tape 30 causes a cross hatched pattern to be developed on ~ the workpiece surface. These cross hatch patterns can be defined by lines which coincide with the direction of rela-tive motion between the workpiece and abrasive coated tape 30 as best shown in Figure 5. Cross latch angle is a function of the rate~s of w~orkpiece rotation and shoe oscil-lation and workpiece surface diameter. The inventors have f,ound that the cross hatch angle defined by Angle D, must exceed 2 in the area of the longitudinal center of the mls/lcm - 12 -: " . , ~, , ~.
..: . . ...
. .. ...
~: : . ,., ~ : :
.
bearing in order to provide acceptable finish quality and bearing performance. This cross hatch angle (Angle D) is somewhat greater than tha-t according to prior art machines and methods and contributes toward improving the quality of bearin8 surfaces generated~
~ odern day crankshafts are often made from nodular iron which has imbedded ferrite nodules. These nodules present themselves as caps on the bearing surface which should be removed in order to provide the desired bearing characteristics. During the course of development of this invention, it was discovered that removal of these ferrite caps was possible by first rotating the workpiece in one direction and then rotating the workpiece in the opposite direction. This process is believed effective since the minute abrasive grains on tape 30 become smoothened on one side, yet remain sharp on the other side, and reversing rotation permits the sharp grain sides to also remove material.
Other types of coated abrasive tape material 30 could be employed in connection with this invention. For example, a metal backed tape which is coated with abrasive material could also be used. However, it is essential that ~tape material 30 be relatively incompressible.
~ ~ ' , ~ mls/lcm - 13 -.
~ :
39~3 Figures 6 and 7 illustrate a second embodiment according to this invention. For this enbodiment~ portions of insert 136 are partially relieved such that they do not cause high contact ~xessure between coated abrasive tape 30 and pin bearing 18~ Figure 6 shcws a pair of opposed relief portions 142 which ar~ defined by arcuate borders 144. The surface of pin bearing 18 mcves with respect t~ inSert 136 in the direction indicated by arrow C. This seaxnd en}rdiment ~auses greater abrasive ~s Prial remcval ta occur at the separated ends of the surfa oe of pin b~aring 180 This second embodimEnt thexe~ore tends to cause the pin bearing ~urfaoe to assume a slightly ~arrel shaped con~iguration, such that its diame~ers at each end are slightly less than the diametex at the oenber. Such ~barrelling" is sameti~es desirable bo achieve optimal bearing surfaces.
A third emboiiment according bo this inwention is æhnwn wQth reference to Figures 8 and 9. Ihis embsdimen~ also p~oes a slightly barrel shap~d journal bearing surfaoe but achieves this result in a differ~t manner than that according to Figures 6 and 7. A Ir~dified cylindrical c~ntour in insert 23S is pro~ce~l 50 that the I:adiUs of ffle ved ~s~t surface at po~?ts ~ ends l~f the ja:n~al bear~ng is less than at the oenter of the j~urnal bearing. As sl~;n by Figure 8, relative m ~ nt of pin bearing 18 w1th respect to insert 236 occurs along the direction indicated by arrow C. As illustrated ~7 Figure 9, portions of the surfa oe of insert 236 near the lateral edges are designated ~y reference characber 254 and have a radius of ~urvature some~hat less than that of central shoe 6eg~ent 256 (these differences ~n radius are exaggerated in Figure 9 for illustration p~rposesJ. This embodlment, therefore, provides another ~ s for generating a nan-cylindrical sur~aoe and a workpiece being ~achined. According to sh~"~7 ~;7q this en~rdiment, such ~ results from ~achining the desired sur~aoe contour directly into stone insert 236 and this cont~ur will be Impressed and ~achined in the c~rresponding workpiece.
: AL ~Y
~2~ 3 A ~ourth enbcdm ent of this inventi~l is illustrated by Figure 10, w~ich ena~les the side wall portion 68 of p m bearing 18 to be //e 7~
finished and f~Ither permits any burrs existing betweeni~k~ radius 46 and the bearing surface to be re~oved~ In accordan oe with this enbodinent, flexible inserts 348 and 350 are prcvided with inserts 36.
~ ~se flexible inserts exert a ccmpressive foroe against coa~ed abrasive tape 30 when the inserts are brought to their ex*reme la~eral positicns.
Although ~he e~ployment of a flexible m~terial for inserts 348 and 350 results in the same shortoomings associated with conventional processes, it is generally not necessary to highly cQntrol the profile shape of these surfa oe s. Sin oe it is neoessary for tape 30 to flex to a considerable extent when brought into contact with side wall portion 68, it is sometimes necessary to provide edge cuts within the ooated tape, according to principles ~ncwn to the prior art. U æ of inserts 348 and 350 further pe~mats the elimination of burrs or sharp edges which may exist at the edges 51 of the ~earing surface o jouxnal 18 when the fillet radius are cut deep into the workpiece ~as shcwn by Figure 10).
By ~cunting inserts 348 and 350 such that they exert a slight compressive load cn the surfac~ of bearLng 1~, t~pe 30 is caused tD
remove such burrs when the insert forces the tape into the fillet.
Figure 11 illustrates a fifth emtodlment according to this inventicn. T~is enbcdlm~nt employs inserts 36 and ~ and lower sho s 62 and 64 as aescribed in cOnneCtiQn with Figure 4. Ihis embodiment differs from the previously described enbodinents in that coated abrasive~tape 430 is used which has a multiplicity of perforations 452 along its lensth. Perfo~ations 452 enable lubricants or cutting fluids to come in contact wi*h the surfaoe s being ~achinedO ~low of lubricant or cutting fluids to the workpiece is oonducted thr3ugh passage 70 pper and lcwer shoes 62 and 64.
A sixth emkcc~nent according ~o this invention is described wqth referen oe to ~igure 12~ As shcwn ~y that Figure, lower shce 56~ is ..~
~' ` ` :'' ,.: "'' .:' ' ` :
. :; :: ' ' ; :
. .
~Si3~3 ~ounted within cradle 566 by a mounting pin 540. These ~ wnting pins p~ it rotation of lower shoe assem~ly 564 with respect to cradle 566.
A similar ~ounting arrangement would also be prc~Tided for upper shoe as~embly 562 Inot shcwn). This arrange~.ent pruvides the desir~ble "floatingl' characteristic as describ~ed with referen oe to ~igure 4 ~herein individual mounting pins 40 are provided for e~ch of the inserts 36, The c.~nstruction illustrated ~y Figure 12 has the primary adTantage of being simpler t~ construct. In operation, this em~o~i~ent performs as described in connection ~ith the earlier described en}odlmEnks.
A seventh em~odime~t according to this invention is shown by Figures 13 and 14. This embodiment prGvides another means of finishing the side wall portions 68 of a bearing 18 or 20. In accordance with this emkodimen~, upper sh oe 62 and/or lower shoe 64 include elastomeric insert 6~2 which is employed to polish the side wall portions 68. As shcwn by Figure 13, upper shce 62 and lcwer shoe 64 are constructed identical to that described with reference to Figure 4 except that one or more of stone inserts 36 is rep-~ced by elastomeric insert 672.
Elastomeric insert 672 is particularly shcwn in detail by Figure 14. As s~cw~ ~y that Figure, insert 672 is ~a~e from an elastoo~ric substance su:~h as a urethane compo~md and includes radiused edge sur~aces 674 and 676. Insert 672 has a lateral width which exceeds that of stone inserts 36 such that as polishing shoe assembly 60 is stroked laterallyj radiused side surfaces 674 and 676 cause ooate~ abrasive tape 30 to contact si~e wall portions 68, thereby microfinishing that area.
Preferably, elastcmeric insert 672 is resiliently biased within the associated shoe Ecrtion, enabl mg it to m~ve radially and laterally with respect to the associated bearing surface. AS sho~n ~y Figure 14, ldteral co~pliance of elasbomeric insert 672 is provided ~y e~ploying drill rcd 678~which flexes, enabling the insert ~o ~ve laterally with respect bo upp~r shoe ~2. Ihe :aximum extent of lateral compliance i5 limited by oontact between elastcmeric insert 672 and insert holder 682.
~adial compliance or insert 672 is provided ~ ~mploying helica~ coil fipring 680 w~ich exerts a dswnward oompressi~e ~oroe upo~ coat~d ~2~ 3~3 abrasive tape 300 The maxi~um extent of radial displaoement is controlled by the position o~ head 684 on drill m d 678. This ~bcdiment provides another nEans of gaining the advantages of a rigid insert in accordance with this invention and furthex finishing the side wall and radius portions of the bearing surface being micrDfinished.
~ hile the abcve descripticn oonstitutes the -prefeIred enbodiments of the present invention, it will be cçprecia~ed that the in~ention is sus oe ptible to m~dification, variati~n. and change wi~hout departing from the proper scope and fair meaning of the acoo~pany mg claIms, `
, ' `': .
Claims (25)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A machine for microfinishing an outside curved surface of a workpiece, comprising:
abrasive coated tape relatively incompressible;
a shoe assembly having means for holding said tape and having a rigid surface forming a predetermined surface shape related to a desired workpiece surface shape, said rigid surface contacting and pressing said tape into contact with said workpiece surface, said rigid surface defining an included angle between the boundaries of contact between said tape and said shoe of greater than 120° and preferably about 160° relative to the center of said curved workpiece surface;
means for causing relative rotation between said workpiece and said shoe assembly, and an arm which supports said shoe assembly such that relative movement between said workpiece surface and said tape occurs as said workpiece is rotated relative to said shoe assembly.
abrasive coated tape relatively incompressible;
a shoe assembly having means for holding said tape and having a rigid surface forming a predetermined surface shape related to a desired workpiece surface shape, said rigid surface contacting and pressing said tape into contact with said workpiece surface, said rigid surface defining an included angle between the boundaries of contact between said tape and said shoe of greater than 120° and preferably about 160° relative to the center of said curved workpiece surface;
means for causing relative rotation between said workpiece and said shoe assembly, and an arm which supports said shoe assembly such that relative movement between said workpiece surface and said tape occurs as said workpiece is rotated relative to said shoe assembly.
2. The machine for microfinishing a surface of a workpiece according to Claim 1 wherein said abrasive coated tape is made from a polyester plastic.
3. The machine for microfinishing a surface of a workpiece according to Claim 1 wherein said abrasive coated tape is made for polyethylene terephthalate.
4. The machine for microfinishing a surface of a workpiece according to Claim 1 wherein said rigid surface is composed of a metal having a roughened surface.
5. The machine for microfinishing a surface of a workpiece according to Claim 1, wherein said rigid surface is formed by at least one insert mounted to said shoe assembly.
6. The machine according to Claim 5 wherein said insert surface extends over greater circumferential distances at its lateral ends such that more material is removed from selected areas of said workpiece surface.
7. The machine according to Claim 5 wherein said insert surface is shaped having segments of varying radii, thereby forming a desired profile shape in said workpiece.
8. The machine according to Claim 5 wherein said workpiece surfaces terminate laterally with radially outwardly projecting surfaces thereby forming a fillet radius therebetween, said insert further including at least one elastomeric insert mounted adjacent said insert which presses said tape into contact with said fillet radius.
9. The machine according to Claim 5 further comprising, at least one second insert made from an elastomeric material having a lateral width greater than said insert, said second insert applying a compressive force against radially outwardly projecting surfaces of said workpiece and thereby finishing said surface.
10. The machine according to Claim 9 further comprising, resilient mounting means for said second insert which becomes deflected as said shoe assembly is moved to its extreme lateral positions.
11. The machine for microfinishing a surface of a workpiece according to Claim 1, wherein said rigid shoe surface is formed by at least one insert mounted to said shoe assembly by a mounting pin which permits slight relative rotation of said insert with respect to said shoe assembly about an axis generally perpendicular to the axis of rotation of said workpiece.
12. The machine for microfinishing a surface of a workpiece according to Claim 1, wherein said rigid surface is formed by at least one insert mounted to said shoe assembly and said shoe assembly is mounted to said arm by a mounting pin such that slight relative rotation of said shoe assembly with respect to said arm is permitted about an axis generally perpendicular to the axis rotation of said workpiece.
13. The machine for microfinishing a surface of a workpiece according to Claim 1, wherein said rigid surface is formed by an insert composed of honing stone material.
14. The machine for microfinishing a surface of a workpiece according to Claim 1 wherein said rigid surface has a hardness exceeding the equivalent of 90 durometer.
15. The machine according to Claim 1 wherein said shoe assembly includes upper and lower shoe portions, each of said portions having at least one insert defining said rigid surface.
16. The machine according to claim 15 wherein all portions of said insert surface extend over the same circumferential distance.
17. The machine according to Claim 1 wherein said included angle is approximately 160°.
18. A method of microfinishing a workpiece an outside curved workpiece surface which comprises the steps of:
rotating said workpiece; and causing a rigid shoe surface to contact and press a relatively incompressible abrasive coated tape against said workpiece surface, said rigid shoe surface having a predetermined shape related to the desired workpiece surface shape and defining an included angle between the boundaries of contact between said tape and said shoe of greater than 120°
and preferably about 160° relative to the center of said curved workpiece surface, whereby a desired workpiece surface shape is generated in said workpiece surface.
rotating said workpiece; and causing a rigid shoe surface to contact and press a relatively incompressible abrasive coated tape against said workpiece surface, said rigid shoe surface having a predetermined shape related to the desired workpiece surface shape and defining an included angle between the boundaries of contact between said tape and said shoe of greater than 120°
and preferably about 160° relative to the center of said curved workpiece surface, whereby a desired workpiece surface shape is generated in said workpiece surface.
19. The method according to Claim 18 wherein said rigid surface has a hardness exceeding the equivalent of go durometer.
20. The method according to Claim 18 wherein said abrasive coated tape is made from a polyester plastic.
21. The method according to Claim 18 wherein said abrasive coated tape is made from polyethylene terephthalate.
22. The method according to Claim 18 further comprising the step of causing an elastomeric insert to press said abrasive coated tape against said workpiece surface and against the radially outwardly projecting surfaces of said workpiece.
23. The method according to Claim 18 further comprising the step of moving said rigid shoe surface laterally as said workpiece is rotated.
24. The method according to Claim 18 further comprising rotating said workpiece in one direction and then rotating said workpiece in an opposite direction.
25. The method according to Claim 11 wherein said included angle is approximately 160°.
* * * * * * * * * *
* * * * * * * * * *
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60820184A | 1984-05-07 | 1984-05-07 | |
| US608,201 | 1984-05-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1265343A true CA1265343A (en) | 1990-02-06 |
Family
ID=24435498
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000475233A Expired - Fee Related CA1265343A (en) | 1984-05-07 | 1985-02-27 | Microfinishing apparatus and method |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0161748B1 (en) |
| JP (1) | JPS60238267A (en) |
| CA (1) | CA1265343A (en) |
| DE (1) | DE3578524D1 (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61178168A (en) * | 1985-02-05 | 1986-08-09 | Honda Motor Co Ltd | Machining of clearance groove for superfinishing |
| US4734964A (en) * | 1985-10-24 | 1988-04-05 | Cooper Lasersonics, Inc. | Apparatus for refurbishing acoustic members |
| JPS62236665A (en) * | 1986-04-08 | 1987-10-16 | Fuji Heavy Ind Ltd | Polishing cloth sheet type automatic grinding device for work |
| US5095663A (en) * | 1989-02-07 | 1992-03-17 | Industrial Metal Products Corporation | Size control shoe for microfinishing machine |
| US5142827A (en) * | 1990-10-05 | 1992-09-01 | J. D. Phillips Corporation | Crankpin grinder and method |
| US5249393A (en) * | 1992-01-21 | 1993-10-05 | Industrial Metal Products, Corp. | Brake drum micro-finishing apparatus |
| DE4444239C3 (en) * | 1994-12-13 | 2003-05-08 | Supfina Grieshaber Gmbh & Co | finishing machine |
| JP3012789B2 (en) * | 1995-08-09 | 2000-02-28 | 株式会社京三製作所 | Wrapping equipment |
| DE59508072D1 (en) * | 1995-12-28 | 2000-04-27 | Supfina Grieshaber Gmbh & Co | Microfinishing machine |
| DE19602933C2 (en) * | 1996-01-27 | 1998-08-27 | Nagel Masch Werkzeug | Method and device for finishing peripheral surfaces on workpieces |
| DE19607778C2 (en) * | 1996-03-01 | 2001-10-11 | Nagel Masch Werkzeug | Device for finishing processing, in particular crankshafts or camshafts |
| DE19714677C5 (en) | 1997-04-09 | 2010-12-02 | Boehringer Werkzeugmaschinen Gmbh | Process for the ready-to-use finishing of rotating parts, in particular the bearing points of crankshafts |
| DE29719168U1 (en) * | 1997-10-29 | 1999-03-04 | Supfina Grieshaber GmbH & Co., 42859 Remscheid | Device for machining cylindrical workpieces |
| DE60142818D1 (en) * | 2000-05-31 | 2010-09-30 | Denso Corp | Piezoelectric component for an injection device |
| JP2007260811A (en) * | 2006-03-28 | 2007-10-11 | Nachi Fujikoshi Corp | Tape lapping device |
| JP5344941B2 (en) * | 2009-01-30 | 2013-11-20 | ダイハツ工業株式会社 | Crankshaft manufacturing method |
| DE102009060926B4 (en) | 2009-12-28 | 2019-04-25 | Niles-Simmons Industrieanlagen Gmbh | Method for finishing the bearing seats of main and crank bearings of crankshafts |
| DE202010006480U1 (en) | 2010-04-30 | 2010-08-05 | Nagel Maschinen- Und Werkzeugfabrik Gmbh | Pressing device for pressing of cutting means, carrier cassette for such a pressing device and device with such a pressing device |
| EP2803445B1 (en) | 2013-05-14 | 2015-07-08 | Supfina Grieshaber GmbH & Co. KG | Device for machining a workpiece with belt finishing |
| DE102014208319B4 (en) | 2014-05-05 | 2021-05-06 | Supfina Grieshaber Gmbh & Co. Kg | Tape finishing device and method of operating a tape finishing device |
| DE102015006672B4 (en) | 2015-05-22 | 2018-11-15 | Neenah Gessner Gmbh | Impregnated abrasive carrier for fine grits and abrasive articles made therefrom |
| BR112020011800A2 (en) * | 2017-12-14 | 2020-11-17 | Thielenhaus Technologies Gmbh | pressure shoe |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1905821A (en) * | 1929-03-15 | 1933-04-25 | Norton Co | Lapping device for cylindrical objects |
| US1908048A (en) * | 1930-09-02 | 1933-05-09 | Norton Co | Lapping machine |
| US1993543A (en) * | 1932-04-29 | 1935-03-05 | Norton Co | Machine for honing and polishing crank shafts |
| US2166009A (en) * | 1938-07-20 | 1939-07-11 | Norton Co | Crankshaft lapping machine |
| US2270522A (en) * | 1940-01-27 | 1942-01-20 | Gen Motors Corp | Crankshaft bearing polishing machine |
| DE881915C (en) * | 1944-03-04 | 1953-07-06 | Messerschmitt Boelkow Blohm | Stone holder for fine drawing grinding work |
| US2502381A (en) * | 1949-06-16 | 1950-03-28 | Norton Co | Lapping arm |
| SU616117A1 (en) * | 1976-04-19 | 1978-07-25 | Ордена Трудового Красного Знамени Научно-Исследовательский Институт Технологии Автомобильной Промышленности | Head for simultaneous finishing of shaft journal and fillets |
| JPS5613584A (en) * | 1979-07-11 | 1981-02-09 | Hitachi Ltd | Setting circuit for data line potential |
| JPS58102666A (en) * | 1981-12-10 | 1983-06-18 | Takegawa Tekko Kk | Belt sander machine for curvature grinding |
-
1985
- 1985-02-27 CA CA000475233A patent/CA1265343A/en not_active Expired - Fee Related
- 1985-03-07 DE DE8585301582T patent/DE3578524D1/en not_active Revoked
- 1985-03-07 EP EP19850301582 patent/EP0161748B1/en not_active Expired
- 1985-03-14 JP JP5156585A patent/JPS60238267A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| EP0161748A2 (en) | 1985-11-21 |
| EP0161748A3 (en) | 1987-04-22 |
| JPH0545380B2 (en) | 1993-07-09 |
| EP0161748B1 (en) | 1990-07-04 |
| JPS60238267A (en) | 1985-11-27 |
| DE3578524D1 (en) | 1990-08-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |