CA2229013C - Improved grinding machine and method of grinding - Google Patents
Improved grinding machine and method of grinding Download PDFInfo
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- CA2229013C CA2229013C CA002229013A CA2229013A CA2229013C CA 2229013 C CA2229013 C CA 2229013C CA 002229013 A CA002229013 A CA 002229013A CA 2229013 A CA2229013 A CA 2229013A CA 2229013 C CA2229013 C CA 2229013C
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- crankshaft
- grinding
- crankpin
- grinding wheel
- wheel
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Abstract
The present invention relates to a method and apparatus for grinding crankpins of a crankshaft. The method is comprised of the steps of mounting the crankshaft between centres; and attaching radially outer regions of the flange to a rotational drive to rotate the crankshaft about its main axis, via a coupling which is torsionally rigid in a plane generally perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalignment. The method further includes advancing the grinding wheel to engage a crankpin region of the crankshaft; and synchronously controlling the position of the grinding wheel whilst the crankshaft is rotated thereby to follow the planetary motion of the crankpin so as to maintain grinding contact between the wheel and the pin. The apparatus is a grinding machine adapted to grind a crankpin region of a crankshaft by synchronously advancing and retracting the grinding wheel as the crankshaft is rotated so that contact is maintained between grinding wheel and crankpin during grinding of the pin. This assures that a true cylindrical surface is ground on the pin.
The grinding machine is comprised of a drive unit for rotating the crankshaft, and a coupling unit which is torsionally rigid in a plane generally perpendicular to the axis of the crankshaft but is readily deformable in other planes to accommodate misalignment, for connecting the drive unit to the crankshaft.
The grinding machine is comprised of a drive unit for rotating the crankshaft, and a coupling unit which is torsionally rigid in a plane generally perpendicular to the axis of the crankshaft but is readily deformable in other planes to accommodate misalignment, for connecting the drive unit to the crankshaft.
Description
Improved Grinding Machine and Method of Grinding 'this is a division of co-pending Canadian Patent Application Serial No. 2,191,069 filed internationally on April 20, 1995.
Field of Invention 'This invention relates to grinding machines.
Background of the Invention When machining articles to a desired shape it is often necessary to rotate: the article (usually termed the workpiece) so that symmetrical machining can be achieved of a given cross section.
:Rotation of the workpiece to be machined can be achieved by securing the workpiece into a rotating chuck. However if the workpiece is not centralised correctly within the clamping jaws of the chuck, it will not rotate in a 'true' fashion and machining will be inaccurate.
.Alternative methods of transmitting rotation involve the use of a tailstock and a headstock to support the article between centres, the headstock transmitting the rotation, directly or indirectly to the workpiece.
'The interengagement between the workpiece and the headstock or driver ma.y be subject to misalignment and offset, which will introduce errors in the machining.
;?fin improved drive transmitting device which will not transmit misalignment or offset to the workpiece is described and claimed in UK Patent Specification 2,289,742.
Summary of the Invention 'The invention lies in a method of grinding a crankpin of a m crankshaft which latter includes a circular flange at one end, comprising the steps of:
- mounting the crankshaft between centres - attaching radially outer regions of the flange to a rotational drive to rotate the crankshaft about its main axis, via a coupling which is torsionally rigid in a plane generally perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalignment, - advancing the grinding wheel to engage a crankpin region of the crankshaft, and - synchronously controlling the position of the grinding wheel whilst the crankshaft is rotated thereby to follow the planetary motion of the crankpin so as to maintain grinding contact between the wheel and the pin.
The advancement and retraction of the grinding wheel is preferably under the control of a computer.
In a method as aforesaid, the crankshaft is preferably mounted between headstock and tailstock centres for rotation about its main axis.
The invention also lies in a machine tool (grinding machine) for machining a crankshaft workpiece wherein drive of the latter is provided by means of at least one drive decoupling means.
The invention thus provides a grinding machine which is adapted to grind a crankpin region of a crankshaft by synchronously advancing and retracting the grinding wheel as the crankshaft is rotated so that contact is maintained between grinding wheel and crankpin during grinding so as to grind a true cylindrical surface on the crankpin, which includes drive means for rotating the crankshaf t, an d a coupling means which is torsionally rigid in a plane generally perpendicular to the axis of the crankshaft but is readily deformable in other planes to accommodate misalignment, for correcting the drive means t.o the crankshaft.
Preferably the drive coupling means comprises a driving member, a driven member which is attachable to the crankshaft so as to rotate the latter, and a connecting means for transferring torque between the driving and the driven members which comprises a laminated device attached to the driving member via at least or_e off axis connection and to the driven member by at least one other off axis connection, the connections being circularly spaced one from the other.
In one embodiment the laminations are formed frcm flexible thin sheet s~~eel so that the connecting means is torsionally rigid in a pl.arie perpendicular to the drive axis so as to ensure rotation is transmitted reliai~ly to the driven member, and the flexibi:Lity of the laminations accommodates any eccentricity developed through misalignment of the driving member and driven member, whereby the driven member and therefore the crankshaf t is decoupled from the drivinc_r member.
Where the crankshaft is to be mounted between a headstock and a tails~~ock of the grinding machine, the components of the drive coupli ng means may be centrally apertured to accommodate the headstock, which can thereby extend axially therethrough to engage one end of the cra~:kshaft .
Preferaf>ly the driven mem~~,er is provided with radially adjustable means for securi:ic it to the crankshaft.
Preferably the securing means is arranged symmetrically to allow centering of the driven member relative to the cranks::~aft .
The adjustment may be provided by pneumatic, electrical or hydrau:Lic means so that release and removal of a crankshaft can be performed automatically.
In a particularly preferred embodiment, two drive coupling means as aforesaid are connected in series, the driven member of the first being connected to the driving member of the second.. Such an arrangement allows even greater coupling to be achievE:d than if only a single drive decoupling means is employed and permits off set as well as misalignment to be accommodated .
The invention is of value in that it permits an NC grinding machine: to be used to cylindrically grind off-axis crankpins of a crankshaft by synchronously advancing and retracting the grindir..g wheel as the crankshaft is rotated.
Thus the invention provides a method of grinding a crankpin of a crankshaft mounted for rotation between centres and driven during the grinding process so as to rotate true about its main axis, wherein a rotating grinding wheel is advanced and retracted under computer control in synchronism with the p~.anetary rotation of the crankpin caused by the rotation of the crankshaft so as to maintain grinding contact between the wheel a:nd the pin at all times during the grinding of the pin.
After grinding a crankpin to a desired diameter, the grinding wheel m<~y be retracted and moved axially so as to register with another crankpin on the crankshaft, to enable the latter to be ground.
A grinding machine embodying the invention thus comprises a headstock and a tailstock between which a crankshaft can be mounted for true rotation between centres, means for driving the crankshaft, and means fo r coupling the drive means thereto i in a manner so as to remove errors due to offset and misalignment, a grinding wheel which can be advanced and retracted towards and away from a crankshaft when the latter is mounted in the machine and aligned with a crankpin thereof, and a computer for controlling the said advance and retraction of the wheel thereby to cause the latter to advance and retract in synchronism with the planetary motion of the crankpin as the crankshaft rotates, so as to maintain grinding contact between the wheel and the pin at all times during the grinding of the pin.
In accordance with one aspect of the present invention there is provided a method of grinding a crankpin of a crankshaft which latter includes a circular flange at one end, comprising the steps of: (1) mounting the crankshaft between centres; (2) attaching radially outer regions of the flange to a rotational drive to rotate the crankshaft about its main axis, via a coupling which is torsionally rigid in a plane generally perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalignment; (3) advancing a grinding wheel to engage a crankpin region of the crankshaft; and (4) synchronously controlling the position of the grinding wheel whilst the crankshaft is rotated thereby to follow the planetary motion of the crankpin so as to maintain grinding contact between the wheel and the pin.
In accordance with another aspect of the present invention there is provided a grinding machine adapted to grind a crankpin of a crankshaft mounted in the machine, comprising means for synchronously advancing and retracting a grinding wheel as the crankshaft is rotated, so that contact is maintained between the grinding wheel and crankpin during grinding of the crankpin so as to grind a true cylindrical surface thereon, drive means for rotating the crankshaft, and a coupling means which is torsionally rigid in a plane generally perpendicular to the axis of the crankshaft but is i~
5a readily deformable in other planes to accommodate misalignment, for connecting the drive means to the crankshaft.
The present invention taken in conjunction with the invention described in co-pending Canadian Patent Application Serial No. 2,191,069 filed internationally on April 20, 1995, will be described in detail hereinbelow with the aid of the accompanying drawings, in which:
Figure 1 is an exploded view of a prior art flexible coupling Figure 2 (a) is a perspective view of a drive decoupling means as applied to a grinding machine;
Figure 2(b) is a section view through the grinding wheel and workpiece as shown in Figure 2(a);
Figure 3(a) is a perspective view of the drive decoupling means as applied to grinding crankpins;
Figure 3(b) is a section through the grinding wheel and crankpin as shown in Figure 3(a)~
Figures 4(a) and 4(b) are views of a clamping ring for clamping an end of a crankshaft to the drive decoupling means;
Figures 5(a) and 5(b) are views of a preferred embodiment of the clamping mechanism;
Figure 6 is a view of part of a grinding machine with a housing encasing a drive decoupling device; and Figure 7 is a vertical section through the grinding machine housing as shown in Figure 6.
Detail.=d Description of emi~odiments Referring to Figure 1, a fl exible coupling device 10 is shown.
The coupling device 10 is shown exploded to illustrate the seDarat~e components .
The ccupiirg device 10 comprises two identical connecting members 12, 14, two laminated discs 16, 18 each formed from a stack of thin sheet steel rings typically formed from shim steel, ar_d a coupling sleeve 20, all the aforesaid being centra7_ly apertured so as to allow a :~eadstock to extend t he re t hrough .
The connecti ng member 12 ~urtizer comprises a cylindrical hub 22, and a circular flange 24 which is cutaway at three circumferentially equally spaced positions. The three resulting lobes 26, 28, 30 are apertured.
The second connecting member 14 is similar in construction.
The coupling sleeve 20 comprises a central cylindrical portion 32 with annular flanges 34, 36 at either end. The flanges 34, 36 are circumferentially cut away to leave lobes in a similar manner as in the flange 24.
In use,. the coupling deTr'_ce 10 is assembled so that the connecting members 12, 14 and coupling sleeve 20 are interconnected by the laminated discs of thi n shim steel rings 16 , 18 .
The lobes of the flange 36 of the coupling sleeve 20 are connected to the disc 16 by .tree hexagon bolts. One of which is shown at 37. Three spaced apertures of the disc 16 are connected to the flange 36.
Similar bolts join the three lobes 26, 28 and 30 of member 12 to the disc 16 at points intermediate the bolts 37.
The sec:or_d connecting disc 18 is similarly connected to the lobes of tie flange 34 by means of three bolts one of which is shown at 39 and similarly to the lobes of the flange 14 by similar bolts one of which is shown at 41.
The members 12, 14 are thus connected to the coupling sleeve 20 through the laminations of the discs 16, 18.
Thus on assembly the interconnection of the individual connecting members 12, 14 and coupling sleeve 20 by use of the flexible laminated thin sheet steel discs 16, 18 ensures a torsion,all y rigid coupling which may be used in a machine tool to transmit drive to a workp loco. The flexibility of the discs 16, 18 absorbs any misalignment or axial offset of the drive member <~nd workpiece relative to each other.
Part of a grinding machine is shown in Figure 2 (a) . Here a coupling device such as shown in Figure 1 is encased within a housing 38.
The grinding machine comprises a grinding wheel 40, a headstock 42, a t:ailstock 44 and dri~re means 46 contained within a housing 48.
The headstock 42 is free to pass through the centre of the coupling device 10 contained within the housing 38. The headstoc:k 42 and tailstock 44 support a workpiece 50.
The coupling device 10 is ccr~Lected at one end to the driving means 46 and at the other en d is detachable secured to the workpiece S0.
Rotation: of the drive means 46 by the motor 52 rotates the coupling device 10. The wor'.tpiece 50 is supported between the headstock 42 and tailstock 44 and is rotated by rotation of the coupling device 10 by the motor 52.
The dec:oupling of the workpiece 50 from the drive means 46 by the coupling device 10 removes errors due to misalignment and offset of the drive means 4 6 relative to the workpiece 50.
Figure 2 (b) shows the grinding wheel 40 and workpiece 50 during a grinding operation. The grinding wheel 40 contacts the workpiece 50 and grinds the surface to a desired diameter.
Figure 3(a) shows how a grinding machine can be used to cylindrically grind off-axis crankpins of a crankshaft 54.
The cr<jnkshaft is supported between the headstock 42 and tailstock 44, and includes a number of cranknins one of which is denoted by reference numer al 56.
The drive means 46 rotates the crankshaft 54 via the coupling device 10 as discussed in relation to Figure 2 (a) .
Rotation of the crankshaft 54 results in each off axis crankpin describing a circle centred on the crankshaft axis as shown in Figure :3 (b) .
The grinding wheel 40 synchronously advances and retracts as the crankshaft 54 rotates and the crankpin 56 describes a circle. This advance and rear action is controlled so that the grinding wheel 40 maintains c:~ntact with the crankpin surface at all times during the rotation of the crankshaft 54, thereby grinding a true cylindrica= surface on the crankpin 56.
Although not shown, the cper ation of the grinding machine is controlled by a computer.
As each crankpin is group d to the desired diameter, the grinding wheel 40 is retracted and moved a~cially along the crankshaft 54 to register w=th another crankpin. In this way i~
an entire crankshaft can be ground automatically.
Attachment of the coupling device 10 to crankshaft 54 is preferably achieved by a clamping ring as shown in Figures 4(a) and 4(b) and 5(a) and 5(b).
In Figure 4(a) a clamping ring 58 is shown having two fixed jaws 60, 62 and an adjustable jaw 64.
Figure 4(b) is a section (not to scale) along line A-A of Figure 4 (a) .
In use the crankshaft 54, is inserted between the three jaws 60, 62, 64 and the adjustable jaw 64 is tightened onto the crankshaft 54 by means of a threaded thrust member 66 such as a screw. Adjustment of the threaded member 66 may be by way of an Allen key spanner 68 so as to cause the j aw 64 to grip the crank 54 against the two fixed jaws 60, 62.
Loosening the threaded member 66 allows removal of the crankshaft 54.
The headstock 42 passes through the central aperture to contact the crankshaft 54 for support.
An alternative clamping device 70 is shown in Figures 5(a) and (b) .
Figure 5(a) shows a clamping ring 70 having as before two fixed jaws 72, 74 and an adjustable jaw 76. A hydraulic piston and cylinder 78 is provided to facilitate insertion and removal.
Figure 5(b) is a section (not to scale) along line B-B of Figure 5(a) and illustrates the adjustable jaw 76 in more detail.
i;
In the clamped position a flange 55 of the crankshaft is held between the adjustable jaw 76 and the fixed jaws 72, 74. The spring 90 acts to urge the adjustable jaw 70 against the flange 55.
As before the headstock 42 passes through central apertures in the drive coupling device 10 and clamping ring 70 to support the crankshaft 54.
To release the crankshaft 54, the hydraulic cylinder 78 is actuated to push down on touch pad 77.
The spring 90 is sufficiently strong as to initially resist this downward force, which is thus transmitted to the ring 70 and the latter displaces downwards until it hits bed 80.
Thereafter continued movement of the piston in the cylinder 78 results in compression of the spring 90 and pivoting of the jaw 76 into the position shown at 76', so all three jaws 72, 74, 76 are now clear of the flange 55.
The crankshaft 54 is now clear and can be removed from the jaws 72, 74, 76.
The bed 80 is spaced by a running clearance from the clamping ring 70.
The interaction of the flange 55, the bed 80 and the spring 90 ensures that all three jaws 72, 74, 76 are moved clear of the flange 55.
Figure 6 shows a grinding machine housing 92 containing a drive means for operating the grinding machine, with a housing 94 attached, to encase a drive decoupling device such as is shown in Figure 1.
The housing 94 encases the drive decoupling device except for a drive plate 96 and jaws 100, 102, 104. An annular attachment 98 fits over the housing 94 and attaches to the grinding m machine' drive housing 92. This ensures that no gap is left between the housing 94 and the housing 92 so as to improve safety and reduce the entry of dirt and swarf during machining.
Jaws 100, 102, 104 are provided for clamping the flanged end of the crankshaft . An adj ustable jaT.v 104 grins the flange against: the two f fixed j aws 10 0 , 102 . Rotat i on of the dri ve plate 5~6 by the drive means, contained within the housing 92, causes rotation of the flanged crankshafts. A headstock 106 passes through the central aperture of the coupling device so as to allow for support of the crankshaft during machining .
The control panel 106 and bed of the machine 108 are shown.
As shoo~n. in Figure 7 the headstock I06 passes through the central aperture of the coupl ing device. The latter comprises connecting members 108, 110 and a coupling sleeve 112 which are interconnected by laminated discs in the form of thin shim-steel rings 114, 116. The coupling device is connected at one end to the driving means and at the other end is detachably securable to the flange of the crankshaft by means of the jaws 100, 10:?, 104 (only 102, 104 of which are visible in Figure 7) .
A faceplate I18 is shown surrounding the headstock 106, with the cover 94 enclosing the entire coupling device shown.
Field of Invention 'This invention relates to grinding machines.
Background of the Invention When machining articles to a desired shape it is often necessary to rotate: the article (usually termed the workpiece) so that symmetrical machining can be achieved of a given cross section.
:Rotation of the workpiece to be machined can be achieved by securing the workpiece into a rotating chuck. However if the workpiece is not centralised correctly within the clamping jaws of the chuck, it will not rotate in a 'true' fashion and machining will be inaccurate.
.Alternative methods of transmitting rotation involve the use of a tailstock and a headstock to support the article between centres, the headstock transmitting the rotation, directly or indirectly to the workpiece.
'The interengagement between the workpiece and the headstock or driver ma.y be subject to misalignment and offset, which will introduce errors in the machining.
;?fin improved drive transmitting device which will not transmit misalignment or offset to the workpiece is described and claimed in UK Patent Specification 2,289,742.
Summary of the Invention 'The invention lies in a method of grinding a crankpin of a m crankshaft which latter includes a circular flange at one end, comprising the steps of:
- mounting the crankshaft between centres - attaching radially outer regions of the flange to a rotational drive to rotate the crankshaft about its main axis, via a coupling which is torsionally rigid in a plane generally perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalignment, - advancing the grinding wheel to engage a crankpin region of the crankshaft, and - synchronously controlling the position of the grinding wheel whilst the crankshaft is rotated thereby to follow the planetary motion of the crankpin so as to maintain grinding contact between the wheel and the pin.
The advancement and retraction of the grinding wheel is preferably under the control of a computer.
In a method as aforesaid, the crankshaft is preferably mounted between headstock and tailstock centres for rotation about its main axis.
The invention also lies in a machine tool (grinding machine) for machining a crankshaft workpiece wherein drive of the latter is provided by means of at least one drive decoupling means.
The invention thus provides a grinding machine which is adapted to grind a crankpin region of a crankshaft by synchronously advancing and retracting the grinding wheel as the crankshaft is rotated so that contact is maintained between grinding wheel and crankpin during grinding so as to grind a true cylindrical surface on the crankpin, which includes drive means for rotating the crankshaf t, an d a coupling means which is torsionally rigid in a plane generally perpendicular to the axis of the crankshaft but is readily deformable in other planes to accommodate misalignment, for correcting the drive means t.o the crankshaft.
Preferably the drive coupling means comprises a driving member, a driven member which is attachable to the crankshaft so as to rotate the latter, and a connecting means for transferring torque between the driving and the driven members which comprises a laminated device attached to the driving member via at least or_e off axis connection and to the driven member by at least one other off axis connection, the connections being circularly spaced one from the other.
In one embodiment the laminations are formed frcm flexible thin sheet s~~eel so that the connecting means is torsionally rigid in a pl.arie perpendicular to the drive axis so as to ensure rotation is transmitted reliai~ly to the driven member, and the flexibi:Lity of the laminations accommodates any eccentricity developed through misalignment of the driving member and driven member, whereby the driven member and therefore the crankshaf t is decoupled from the drivinc_r member.
Where the crankshaft is to be mounted between a headstock and a tails~~ock of the grinding machine, the components of the drive coupli ng means may be centrally apertured to accommodate the headstock, which can thereby extend axially therethrough to engage one end of the cra~:kshaft .
Preferaf>ly the driven mem~~,er is provided with radially adjustable means for securi:ic it to the crankshaft.
Preferably the securing means is arranged symmetrically to allow centering of the driven member relative to the cranks::~aft .
The adjustment may be provided by pneumatic, electrical or hydrau:Lic means so that release and removal of a crankshaft can be performed automatically.
In a particularly preferred embodiment, two drive coupling means as aforesaid are connected in series, the driven member of the first being connected to the driving member of the second.. Such an arrangement allows even greater coupling to be achievE:d than if only a single drive decoupling means is employed and permits off set as well as misalignment to be accommodated .
The invention is of value in that it permits an NC grinding machine: to be used to cylindrically grind off-axis crankpins of a crankshaft by synchronously advancing and retracting the grindir..g wheel as the crankshaft is rotated.
Thus the invention provides a method of grinding a crankpin of a crankshaft mounted for rotation between centres and driven during the grinding process so as to rotate true about its main axis, wherein a rotating grinding wheel is advanced and retracted under computer control in synchronism with the p~.anetary rotation of the crankpin caused by the rotation of the crankshaft so as to maintain grinding contact between the wheel a:nd the pin at all times during the grinding of the pin.
After grinding a crankpin to a desired diameter, the grinding wheel m<~y be retracted and moved axially so as to register with another crankpin on the crankshaft, to enable the latter to be ground.
A grinding machine embodying the invention thus comprises a headstock and a tailstock between which a crankshaft can be mounted for true rotation between centres, means for driving the crankshaft, and means fo r coupling the drive means thereto i in a manner so as to remove errors due to offset and misalignment, a grinding wheel which can be advanced and retracted towards and away from a crankshaft when the latter is mounted in the machine and aligned with a crankpin thereof, and a computer for controlling the said advance and retraction of the wheel thereby to cause the latter to advance and retract in synchronism with the planetary motion of the crankpin as the crankshaft rotates, so as to maintain grinding contact between the wheel and the pin at all times during the grinding of the pin.
In accordance with one aspect of the present invention there is provided a method of grinding a crankpin of a crankshaft which latter includes a circular flange at one end, comprising the steps of: (1) mounting the crankshaft between centres; (2) attaching radially outer regions of the flange to a rotational drive to rotate the crankshaft about its main axis, via a coupling which is torsionally rigid in a plane generally perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalignment; (3) advancing a grinding wheel to engage a crankpin region of the crankshaft; and (4) synchronously controlling the position of the grinding wheel whilst the crankshaft is rotated thereby to follow the planetary motion of the crankpin so as to maintain grinding contact between the wheel and the pin.
In accordance with another aspect of the present invention there is provided a grinding machine adapted to grind a crankpin of a crankshaft mounted in the machine, comprising means for synchronously advancing and retracting a grinding wheel as the crankshaft is rotated, so that contact is maintained between the grinding wheel and crankpin during grinding of the crankpin so as to grind a true cylindrical surface thereon, drive means for rotating the crankshaft, and a coupling means which is torsionally rigid in a plane generally perpendicular to the axis of the crankshaft but is i~
5a readily deformable in other planes to accommodate misalignment, for connecting the drive means to the crankshaft.
The present invention taken in conjunction with the invention described in co-pending Canadian Patent Application Serial No. 2,191,069 filed internationally on April 20, 1995, will be described in detail hereinbelow with the aid of the accompanying drawings, in which:
Figure 1 is an exploded view of a prior art flexible coupling Figure 2 (a) is a perspective view of a drive decoupling means as applied to a grinding machine;
Figure 2(b) is a section view through the grinding wheel and workpiece as shown in Figure 2(a);
Figure 3(a) is a perspective view of the drive decoupling means as applied to grinding crankpins;
Figure 3(b) is a section through the grinding wheel and crankpin as shown in Figure 3(a)~
Figures 4(a) and 4(b) are views of a clamping ring for clamping an end of a crankshaft to the drive decoupling means;
Figures 5(a) and 5(b) are views of a preferred embodiment of the clamping mechanism;
Figure 6 is a view of part of a grinding machine with a housing encasing a drive decoupling device; and Figure 7 is a vertical section through the grinding machine housing as shown in Figure 6.
Detail.=d Description of emi~odiments Referring to Figure 1, a fl exible coupling device 10 is shown.
The coupling device 10 is shown exploded to illustrate the seDarat~e components .
The ccupiirg device 10 comprises two identical connecting members 12, 14, two laminated discs 16, 18 each formed from a stack of thin sheet steel rings typically formed from shim steel, ar_d a coupling sleeve 20, all the aforesaid being centra7_ly apertured so as to allow a :~eadstock to extend t he re t hrough .
The connecti ng member 12 ~urtizer comprises a cylindrical hub 22, and a circular flange 24 which is cutaway at three circumferentially equally spaced positions. The three resulting lobes 26, 28, 30 are apertured.
The second connecting member 14 is similar in construction.
The coupling sleeve 20 comprises a central cylindrical portion 32 with annular flanges 34, 36 at either end. The flanges 34, 36 are circumferentially cut away to leave lobes in a similar manner as in the flange 24.
In use,. the coupling deTr'_ce 10 is assembled so that the connecting members 12, 14 and coupling sleeve 20 are interconnected by the laminated discs of thi n shim steel rings 16 , 18 .
The lobes of the flange 36 of the coupling sleeve 20 are connected to the disc 16 by .tree hexagon bolts. One of which is shown at 37. Three spaced apertures of the disc 16 are connected to the flange 36.
Similar bolts join the three lobes 26, 28 and 30 of member 12 to the disc 16 at points intermediate the bolts 37.
The sec:or_d connecting disc 18 is similarly connected to the lobes of tie flange 34 by means of three bolts one of which is shown at 39 and similarly to the lobes of the flange 14 by similar bolts one of which is shown at 41.
The members 12, 14 are thus connected to the coupling sleeve 20 through the laminations of the discs 16, 18.
Thus on assembly the interconnection of the individual connecting members 12, 14 and coupling sleeve 20 by use of the flexible laminated thin sheet steel discs 16, 18 ensures a torsion,all y rigid coupling which may be used in a machine tool to transmit drive to a workp loco. The flexibility of the discs 16, 18 absorbs any misalignment or axial offset of the drive member <~nd workpiece relative to each other.
Part of a grinding machine is shown in Figure 2 (a) . Here a coupling device such as shown in Figure 1 is encased within a housing 38.
The grinding machine comprises a grinding wheel 40, a headstock 42, a t:ailstock 44 and dri~re means 46 contained within a housing 48.
The headstock 42 is free to pass through the centre of the coupling device 10 contained within the housing 38. The headstoc:k 42 and tailstock 44 support a workpiece 50.
The coupling device 10 is ccr~Lected at one end to the driving means 46 and at the other en d is detachable secured to the workpiece S0.
Rotation: of the drive means 46 by the motor 52 rotates the coupling device 10. The wor'.tpiece 50 is supported between the headstock 42 and tailstock 44 and is rotated by rotation of the coupling device 10 by the motor 52.
The dec:oupling of the workpiece 50 from the drive means 46 by the coupling device 10 removes errors due to misalignment and offset of the drive means 4 6 relative to the workpiece 50.
Figure 2 (b) shows the grinding wheel 40 and workpiece 50 during a grinding operation. The grinding wheel 40 contacts the workpiece 50 and grinds the surface to a desired diameter.
Figure 3(a) shows how a grinding machine can be used to cylindrically grind off-axis crankpins of a crankshaft 54.
The cr<jnkshaft is supported between the headstock 42 and tailstock 44, and includes a number of cranknins one of which is denoted by reference numer al 56.
The drive means 46 rotates the crankshaft 54 via the coupling device 10 as discussed in relation to Figure 2 (a) .
Rotation of the crankshaft 54 results in each off axis crankpin describing a circle centred on the crankshaft axis as shown in Figure :3 (b) .
The grinding wheel 40 synchronously advances and retracts as the crankshaft 54 rotates and the crankpin 56 describes a circle. This advance and rear action is controlled so that the grinding wheel 40 maintains c:~ntact with the crankpin surface at all times during the rotation of the crankshaft 54, thereby grinding a true cylindrica= surface on the crankpin 56.
Although not shown, the cper ation of the grinding machine is controlled by a computer.
As each crankpin is group d to the desired diameter, the grinding wheel 40 is retracted and moved a~cially along the crankshaft 54 to register w=th another crankpin. In this way i~
an entire crankshaft can be ground automatically.
Attachment of the coupling device 10 to crankshaft 54 is preferably achieved by a clamping ring as shown in Figures 4(a) and 4(b) and 5(a) and 5(b).
In Figure 4(a) a clamping ring 58 is shown having two fixed jaws 60, 62 and an adjustable jaw 64.
Figure 4(b) is a section (not to scale) along line A-A of Figure 4 (a) .
In use the crankshaft 54, is inserted between the three jaws 60, 62, 64 and the adjustable jaw 64 is tightened onto the crankshaft 54 by means of a threaded thrust member 66 such as a screw. Adjustment of the threaded member 66 may be by way of an Allen key spanner 68 so as to cause the j aw 64 to grip the crank 54 against the two fixed jaws 60, 62.
Loosening the threaded member 66 allows removal of the crankshaft 54.
The headstock 42 passes through the central aperture to contact the crankshaft 54 for support.
An alternative clamping device 70 is shown in Figures 5(a) and (b) .
Figure 5(a) shows a clamping ring 70 having as before two fixed jaws 72, 74 and an adjustable jaw 76. A hydraulic piston and cylinder 78 is provided to facilitate insertion and removal.
Figure 5(b) is a section (not to scale) along line B-B of Figure 5(a) and illustrates the adjustable jaw 76 in more detail.
i;
In the clamped position a flange 55 of the crankshaft is held between the adjustable jaw 76 and the fixed jaws 72, 74. The spring 90 acts to urge the adjustable jaw 70 against the flange 55.
As before the headstock 42 passes through central apertures in the drive coupling device 10 and clamping ring 70 to support the crankshaft 54.
To release the crankshaft 54, the hydraulic cylinder 78 is actuated to push down on touch pad 77.
The spring 90 is sufficiently strong as to initially resist this downward force, which is thus transmitted to the ring 70 and the latter displaces downwards until it hits bed 80.
Thereafter continued movement of the piston in the cylinder 78 results in compression of the spring 90 and pivoting of the jaw 76 into the position shown at 76', so all three jaws 72, 74, 76 are now clear of the flange 55.
The crankshaft 54 is now clear and can be removed from the jaws 72, 74, 76.
The bed 80 is spaced by a running clearance from the clamping ring 70.
The interaction of the flange 55, the bed 80 and the spring 90 ensures that all three jaws 72, 74, 76 are moved clear of the flange 55.
Figure 6 shows a grinding machine housing 92 containing a drive means for operating the grinding machine, with a housing 94 attached, to encase a drive decoupling device such as is shown in Figure 1.
The housing 94 encases the drive decoupling device except for a drive plate 96 and jaws 100, 102, 104. An annular attachment 98 fits over the housing 94 and attaches to the grinding m machine' drive housing 92. This ensures that no gap is left between the housing 94 and the housing 92 so as to improve safety and reduce the entry of dirt and swarf during machining.
Jaws 100, 102, 104 are provided for clamping the flanged end of the crankshaft . An adj ustable jaT.v 104 grins the flange against: the two f fixed j aws 10 0 , 102 . Rotat i on of the dri ve plate 5~6 by the drive means, contained within the housing 92, causes rotation of the flanged crankshafts. A headstock 106 passes through the central aperture of the coupling device so as to allow for support of the crankshaft during machining .
The control panel 106 and bed of the machine 108 are shown.
As shoo~n. in Figure 7 the headstock I06 passes through the central aperture of the coupl ing device. The latter comprises connecting members 108, 110 and a coupling sleeve 112 which are interconnected by laminated discs in the form of thin shim-steel rings 114, 116. The coupling device is connected at one end to the driving means and at the other end is detachably securable to the flange of the crankshaft by means of the jaws 100, 10:?, 104 (only 102, 104 of which are visible in Figure 7) .
A faceplate I18 is shown surrounding the headstock 106, with the cover 94 enclosing the entire coupling device shown.
Claims (14)
1. A method of grinding a crankpin of a crankshaft which latter includes a circular flange at one end, comprising the steps of:
(1) mounting the crankshaft between centres;
(2) attaching radially outer regions of the flange to a rotational drive to rotate the crankshaft about its main axis, via a coupling which is torsionally rigid in a plane generally perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalignment;
(3) advancing a grinding wheel to engage a crankpin region of the crankshafts; and (4) synchronously controlling the position of the grinding wheel whilst the crankshaft is rotated thereby to follow the planetary motion of the crankpin so as to maintain grinding contact between the wheel and the pin.
(1) mounting the crankshaft between centres;
(2) attaching radially outer regions of the flange to a rotational drive to rotate the crankshaft about its main axis, via a coupling which is torsionally rigid in a plane generally perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalignment;
(3) advancing a grinding wheel to engage a crankpin region of the crankshafts; and (4) synchronously controlling the position of the grinding wheel whilst the crankshaft is rotated thereby to follow the planetary motion of the crankpin so as to maintain grinding contact between the wheel and the pin.
2. A method as claimed in claim 1, wherein advancement and retraction of the grinding wheel is under the control of a computer.
3. A method as claimed in claim 2, wherein the crankshaft is mounted between headstock and tailstock centres for rotation about its main axis.
4. A grinding machine adapted to grind a crankpin of a crankshaft mounted in the machine, comprising means for synchronously advancing and retracting a grinding wheel as the crankshaft is rotated, so that contact is maintained between the grinding wheel and crankpin during grinding of the crankpin so as to grind a true cylindrical surface thereon, drive means for rotating the crankshaft, and a coupling means which is torsionally rigid in a plane generally perpendicular to the axis of the crankshaft but is readily deformable in other planes to accommodate misalignment, for connecting the drive means to the crankshaft.
5. A grinding machine as claimed in claim 4, wherein the drive coupling means comprises a driving member, a driven member which is attachable to the crankshaft so as to rotate the latter, and a connecting means for transferring torque between the driving and driven members which comprises a laminated device attached to the driving member via at least one off axis connection and to the driven member by at least one other off axis connection, the connections being circularly spaced one from the other.
6. A grinding machine as claimed in claim 5, wherein the laminated device comprises laminations formed from flexible thin sheet steel so that the connecting means is torsionally rigid in a plane perpendicular to the drive axis so as to ensure rotation is transmitted reliably to the driven member, and the flexibility of the laminations accommodates any eccentricity developed through misalignment of the driving member and driven member, whereby the driven member and therefore the crankshaft is decoupled from the driving member.
7. A grinding machine as claimed in any of claims 4 to 6, which includes a headstock and a tailstock and wherein the components of the drive coupling means are centrally apertured to enable the headstock to extend axially therethrough, to engage one end of the crankshaft.
8. A grinding machine as claimed in any of claims 5 to 7, wherein the driven member is provided with radially adjustable securing means for securing it to the crankshaft.
9. A grinding machine as claimed in claim 8, wherein the securing means is arranged symmetrically to allow centering of the driven member relative to the crankshaft.
10. A grinding machine as claimed in claim 8 or 9, wherein the adjustment is effected by pneumatic, electrical or hydraulic means.
11. A grinding machine as claimed in any of claims 4 to 10, wherein two drive coupling means are connected in series, the driven member of the first being connected to the driving member of the second, whereby offset as well as misalignment can be accommodated.
12. A grinding machine as claimed in any of claims 4 to 11, further comprising a computer adapted to control and synchronise the advancing and retracting of the grinding wheel as the crankshaft is rotated.
13. A method of grinding a crankpin of a crankshaft mounted for rotation between centres and driven during the grinding process so as to rotate true about its main axis, wherein a rotating grinding wheel is advanced and retracted under computer control in synchronism with the planetary rotation of the crankpin caused by the rotation of the crankshaft so as to maintain grinding contact between the wheel and the pin at all times during the grinding of the pin.
14. A method as claimed in claim 13, wherein as each workpiece is ground to the desired diameter, the grinding wheel is retracted and moved axially to register with another crankpin on the crankshaft to enable the latter to be ground.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9410682A GB9410682D0 (en) | 1994-05-27 | 1994-05-27 | Drive transmitting device |
| GB9410682.0 | 1994-05-27 | ||
| GB9424139.5 | 1994-11-30 | ||
| GB9424139A GB9424139D0 (en) | 1994-11-30 | 1994-11-30 | Further workpiece driver for grinding machine |
| CA002191069A CA2191069C (en) | 1994-05-27 | 1995-04-20 | Drive transmitting device |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002191069A Division CA2191069C (en) | 1994-05-27 | 1995-04-20 | Drive transmitting device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2229013A1 CA2229013A1 (en) | 1995-12-07 |
| CA2229013C true CA2229013C (en) | 2003-02-04 |
Family
ID=27170229
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002229013A Expired - Fee Related CA2229013C (en) | 1994-05-27 | 1995-04-20 | Improved grinding machine and method of grinding |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2229013C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112757070A (en) * | 2021-01-13 | 2021-05-07 | 王海 | Surface grinding device is used in carbon fiber roller combined material processing |
-
1995
- 1995-04-20 CA CA002229013A patent/CA2229013C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2229013A1 (en) | 1995-12-07 |
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| EEER | Examination request | ||
| MKLA | Lapsed |