U.S. patent application number 12/129906 was filed with the patent office on 2008-12-18 for grinding method.
This patent application is currently assigned to JTEKT CORPORATION. Invention is credited to Naoki Itoh, Akira Watanabe.
Application Number | 20080311828 12/129906 |
Document ID | / |
Family ID | 40132781 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080311828 |
Kind Code |
A1 |
Itoh; Naoki ; et
al. |
December 18, 2008 |
GRINDING METHOD
Abstract
It is provided that a grinding method of a rotating workpiece W
having a cylindrical part and at least one end face beside the
cylindrical part. The grinding wheel 30 has a rotational axis
parallel to a rotational axis of the workpiece W and has an
external surface 30FM, at least one side surface 30SM and at least
one R-part 30KM between the external surface 30FM and the side
surface 30DM. The grinding wheel 30 is moved backward in oblique
direction to the end face to grind the end face for rough grinding
in a process [1]. The grinding wheel is moved forward perpendicular
to the rotational axis of the workpiece to grind the end face for
finish grinding in a process [2a] and to grind the cylindrical part
for rough grinding in a process [2b].
Inventors: |
Itoh; Naoki; (Kariya-shi,
JP) ; Watanabe; Akira; (Chita-gun, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
JTEKT CORPORATION
Osaka-shi
JP
|
Family ID: |
40132781 |
Appl. No.: |
12/129906 |
Filed: |
May 30, 2008 |
Current U.S.
Class: |
451/49 |
Current CPC
Class: |
B24B 5/01 20130101; B24B
5/42 20130101 |
Class at
Publication: |
451/49 |
International
Class: |
B24B 1/00 20060101
B24B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2007 |
JP |
2007-157291 |
Claims
1. A grinding method of a rotating workpiece having a cylindrical
part and at least one end face beside the cylindrical part with a
rotating grinding wheel which relatively moves to the workpiece,
wherein the grinding wheel has a rotational axis parallel to a
rotational axis of the workpiece and has an external surface
parallel to its rotational axis, at least one side surface
perpendicular to its rotational axis and at least one R-part
between the external surface and the side surface, the grinding
method comprises processes of: setting the grinding wheel close to
the end face of the workpiece and moving the grinding wheel
backward in oblique direction to the end face to grind the end face
for rough grinding by the side surface; and moving the grinding
wheel forward perpendicular to the rotational axis of the workpiece
to grind the end face for finish grinding by the R-part and to
grind the cylindrical part for rough grinding by the R-part and the
external surface.
2. The grinding method according to claim 1, wherein the grinding
wheel inwardly has a back taper surface connected with the side
surface, and wherein the back taper surface is used for the rough
grinding of the end face.
3. A grinding method of a rotating workpiece having a cylindrical
part and two end faces at both sides of the cylindrical part with a
rotating grinding wheel which relatively moves to the workpiece,
wherein the grinding wheel has a rotational axis parallel to a
rotational axis of the workpiece and has an external surface
parallel to its rotational axis, two side surfaces perpendicular to
its rotational axis and two R-parts between the external surface
and the side surfaces, the grinding method comprises processes of:
setting the grinding wheel close to one of the end faces of the
workpiece and moving the grinding wheel backward in oblique
direction to the one end face to grind the one end face for rough
grinding by one of the side surfaces; moving the grinding wheel
forward perpendicular to the rotational axis of the workpiece to
grind the one end face for finish grinding by one of the R-parts
and to grind a part of the cylindrical part close to the one end
face for rough grinding by the one R-part and the external surface;
setting the grinding wheel close to the other end face of the
workpiece and moving the grinding wheel backward in oblique
direction to the other end face to grind the other end face for
rough grinding by the other side surface; moving the grinding wheel
forward perpendicular to the rotational axis of the workpiece to
grind the other end face for finish grinding by the other R-part
and to grind a part of the cylindrical part close to the other end
face for rough grinding by the other R-part and the external
surface; and moving the grinding wheel parallel to the rotational
axis of the workpiece for finish grinding of the cylindrical part
by the one R-part and the external surface.
4. The grinding method according to claim 3, wherein the grinding
wheel inwardly has a back taper surface connected with the side
surface, and wherein the back taper surface is used for the rough
grinding of the end face.
5. A grinding method of a rotating workpiece having at least one
end face with a rotating grinding wheel which relatively moves to
the workpiece, wherein the grinding wheel has a rotational axis
parallel to a rotational axis of the workpiece and has an external
surface parallel to its rotational axis and at least one side
surface perpendicular to its rotational axis, the grinding method
comprises processes of: setting the grinding wheel close to the end
face of the workpiece and moving the grinding wheel backward in
oblique direction to the end face to grind the end face for rough
grinding by the side surface; and moving the grinding wheel forward
perpendicular to the rotational axis of the workpiece to grind the
end face for finish grinding by a boundary between the external
surface and the side surface.
6. The grinding method according to claim 5, wherein the grinding
wheel inwardly has a back taper surface connected with the side
surface, and wherein the back taper surface is used for the rough
grinding of the end face.
Description
INCORPORATION BY REFERENCE
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to Japanese Patent Application No. 2007-157291, filed on
Jun. 14, 2007. The contents of that application are incorporated
herein by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a grinding method of a workpiece,
for example, a crankshaft, which has an end face, and/or which has
an end face and a cylindrical part.
[0004] 2. Discussion of the Background
[0005] It is well-known that a conventional grinding machine which
grinds cylindrical parts (pins, journals and/or etc.) and end faces
(shoulder parts and/or etc.) of a crankshaft. The rotational axis
of the crankshaft is parallel to the cylindrical parts and
perpendicular to the end faces.
[0006] Japanese patent application publication No. 2005-324313
discloses a grinding method of the cylindrical part and the end
faces. For grinding the cylindrical part and the end faces, as
shown in FIGS. 1 and 2, a grinding wheel 30 is fed in oblique
direction ([A1a], [A1b], [A1] and [A4]), then in thrust direction
([A2] and [A5]). In FIGS. 1 and 2, hatching regions with horizontal
and vertical lines indicate grinding allowances ground by an R-part
30KM of the grinding wheel 30. Hatching regions with only
horizontal lines are ground by parts of grinding wheel 30 except
the R-part 30KM.
[0007] With referring to FIGS. 1(A) and 1(B), there will be
explained grinding method of one cylindrical part and one end face.
In the prior art, first process [A1] has a rough grinding step of
the end face [A1a] and a rough grinding step of the cylindrical
part [A1b], as shown in FIG. 1(A). In the step [A1a], the grinding
wheel 30 is obliquely fed to C-axis so as to remove a grinding
allowance [A1a(1)]. During the step [A1a], the R-part 30KM of the
grinding wheel 30 is used (works). Where the grinding wheel 30 is
further fed to C-axis obliquely, an external surface 30FM of the
grinding wheel 30 reaches the cylindrical part of the workpiece W
and the step [A1b] begins. In the step [A1b], the grinding wheel 30
is continuously fed so that the R-part 30KM removes the grinding
allowance [A1b(1)] and the external surface 30FM removes a grinding
allowance [A1b(0)]. Thus, during the step [A1b], the R-part 30KM
and the external surface 30FM of the grinding wheel 30 are used
(work).
[0008] In sequence, second process [A2] takes place as shown in
FIG. 1(B). The grinding wheel 30 is fed in substantial parallel to
C-axis for finish grinding of the end face. In the second process
[A2], the R-part 30KM (the width of .DELTA.1 equals to f/n of the
R-part 30KM) and a side 30SM of the grinding wheel 30 are used
(work) in order to remove a grinding allowance [A2(1)]. ".DELTA.1"
is depth of grinding per a revolution of a spindle (mm/rev), "f" is
feeding speed (mm/min) in Z-axis direction, and "n" is revolution
speed (rev/min) of the spindle. The width of .DELTA.1 (equals to
f/n of the R-part 30KM) grinds a part of the workpiece W which
reaches a region A-P of the grinding wheel 30, as shown in FIG.
1(B). The side 30SM grinds a part of the workpiece W which passes
through the region A-P until reaching a region B-P. In the second
process [A2], finish grinding of the cylindrical part may take
place. As explained, in the processes A1 and A2 of the prior art,
grinding allowances [A1a(1)], [A1b(1)] and [A2(1)] are removed by
the R-part 30KM of the grinding wheel 30.
[0009] Next, there will be explained grinding method of one
cylindrical part and two end faces with referring to FIG. 2. FIG. 2
shows all processes [A1] to [A6] in order to grind the cylindrical
part and the end faces which are located both sides of the
cylindrical part, e.g., crankpin and crank arms of a crankshaft. In
the processes [A1] and [A2], one end face is ground by substantial
same processes [A1] and [A2] of FIGS. 1(A) and 1(B). In the process
[A3], the grinding wheel 30 is fed without grinding. In the
processes [A4] and [A5], the other end face is ground by
substantial same processes [A1] and [A2] of FIGS. 1(A) and 1(B). In
the process [A6], the grinding wheel 30 is fed in parallel of
C-axis for finish grinding of the cylindrical part. The R-part 30KM
of the grinding wheel 30 grinds the hatching regions with
horizontal and vertical lines as the grinding allowances.
[0010] In the prior art, the removal amount (grinding allowances)
by the R-part 30KM of the grinding wheel 30 is larger than by the
other parts. Thus the grinding wheel of the prior art wears away
early at the R-part 30KM so as to shorten the durability of the
grinding wheel 30 relatively. Further the shape of R-part 30KM is
transferred to the boundary between the cylindrical part and the
end face of the workpiece. Therefore, when the R-part 30KM looses
its shape because of frequency of usage, the workpiece may not
obtain sufficient precision and may be defective.
SUMMARY OF THE INVENTION
[0011] According to the invention, it is provided that a grinding
method of a rotating workpiece having a cylindrical part and at
least one end face beside the cylindrical part. A grinding wheel
has a rotational axis parallel to a rotational axis of the
workpiece and has an external surface, at least one side surface
and at least one R-part between the external surface and the side
surface. The grinding wheel is moved backward in oblique direction
to the end face to grind the end face for rough grinding by the
side surface. Next, the grinding wheel is moved forward
perpendicular to the rotational axis of the workpiece to grind the
end face for finish grinding by the R-part and to grind the
cylindrical part for rough grinding by the R-part and the external
surface.
[0012] The present invention also provides a grinding method of a
rotating workpiece having a cylindrical part and two end faces at
both sides of the cylindrical part. A grinding wheel has a
rotational axis parallel to a rotational axis of the workpiece and
has an external surface, two side surfaces and two R-parts between
the external surface and the side surfaces. The grinding wheel is
moved backward in oblique direction to the one end face to grind
the one end face for rough grinding by one of the side surfaces.
Next, the grinding wheel is moved forward perpendicular to the
rotational axis of the workpiece to grind the one end face for
finish grinding by one of the R-parts and to grind a part of the
cylindrical part close to the one end face for rough grinding by
the one R-part and the external surface. Further, the grinding
wheel is moved backward in oblique direction to the other end face
to grind the other end face for rough grinding by the other side
surface. Next, the grinding wheel is moved forward perpendicular to
the rotational axis of the workpiece to grind the other end face
for finish grinding by the other R-part and to grind a part of the
cylindrical part close to the other end face for rough grinding by
the other R-part and the external surface. Finally, the grinding
wheel is moved parallel to the rotational axis of the workpiece for
finish grinding of the cylindrical part by the one R-part and the
external surface.
[0013] The present invention further provides a grinding method of
a rotating workpiece having at least one end face. A grinding wheel
has a rotational axis parallel to a rotational axis of the
workpiece and has an external surface and at least one side
surface. The grinding wheel is moved backward in oblique direction
to the end face to grind the end face for rough grinding by the
side surface. Next, the grinding wheel is moved forward
perpendicular to the rotational axis of the workpiece to grind the
end face for finish grinding by a boundary between the external
surface and the side surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Various objects, features and many of the attendant
advantages of the present invention will be readily appreciated as
the same becomes better understood by reference to the following
detailed description of the preferred embodiments when considered
in connection with the accompanying drawings, in which:
[0015] FIGS. 1(A) and 1(B) are explanatory drawings of a prior
art,
[0016] FIG. 2 is an explanatory drawing of another prior art,
[0017] FIG. 3 is a plan view of a grinding machine applied to a
first embodiment of the present invention,
[0018] FIG. 4 is a side view of FIG. 3,
[0019] FIG. 5 shows a grinding wheel of the grinding machine,
[0020] FIGS. 6(A) and 6(B) are explanatory drawings of the first
embodiment,
[0021] FIG. 7 an explanatory drawing of a second embodiment of the
invention,
[0022] FIGS. 8(A) and 8(B) show examples of a workpiece ground by
the invention, and
[0023] FIG. 9 is an explanatory drawing of a third embodiment of
the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] A first embodiment of a grinding method related to the
present invention will be described with reference to FIGS. 3 to 6
and 8. FIG. 3 shows a schematic plan view of a grinding machine 1
which grinds a workpiece W having one or more end faces and
cylindrical parts, e.g. a crankshaft. FIG. 4 shows a schematic side
view of the grinding machine 1 along A-direction in FIG. 3, and
FIG. 5 shows an external view and a section view of a grinding
wheel 30. FIGS. 8(A) and 8(B) respectively show a crankshaft W1 and
a transmission shaft W2 as examples of the workpiece W.
[0025] [Grinding Machine 1]
[0026] The grinding machine 1 comprises a base 2, a spindle table
TB1, a wheel table TB2 and a computerized numerical controller
(CNC) 40. The grinding wheel 30 is a disc-like and is disposed on
the wheel table TB2. In detail, the grinding wheel 30 attached to a
wheel drive motor 24 mounted on the wheel table TB2, and is driven
by the wheel drive motor 24 about a wheel rotational axis TZ which
is parallel to Z-axis. The grinding wheel 30, for example, has an
iron core 30b and a CBN grindstone 30a surrounding the iron core
30b. Z-axis is an axis of a ball screw 23B (described hereinafter)
and is parallel to C-axis which is a rotational axis of the
workpiece W. As shown in FIG. 5, the CBN grindstone 30a of the
grinding wheel 30 has external surface 30FM, side surfaces 30SM,
R-parts 30KM which is a boundary between the external surface 30FM
and the side surfaces 30SM, internal surfaces 30RM and back taper
surfaces 30BM. Respective back taper surfaces 30BM have a
predetermined angle .theta.. The grindstone 30a may not have the
back taper surfaces 30BM like the prior art in FIGS. 1(A) and
1(B).
[0027] A coolant nozzle 70 is a nozzle which is configured to
supply coolant for lubrication of the grinding point between the
workpiece W and the grinding wheel 30. The coolant is supplied to
the grinding point from a coolant supply pump 74 controlled by the
CNC 40 via the coolant nozzle 70. A coolant valve 72 is controlled
by the CNC 40 in order to adjust the amount of coolant supply.
[0028] The wheel table TB2 is driven by a wheel table motor 22 to
move along X-axis through a ball screw 22 and a nut (not shown)
fixed on the wheel table TB2. X-axis is an axis of the ball screw
22 and is perpendicular to Z-axis and C-axis.
[0029] The spindle table TB1 is driven by a spindle table motor 23
to move along Z-axis through the ball screw 23B and a nut (not
shown) fixed on the spindle table TB1. A tail stock 21T is fixed on
the spindle table TB1. Facing the tail stock 21T on the spindle
table TB1, a head stock 21D is slidably mounted in order to adjust
variety of lengths of the workpieces W. A spindle motor 21 is
installed into the head stock 21D and has a clamp 21C to clamp the
workpiece W rotatably about C-axis. The workpiece W is held by the
clamp 21C and a tail spindle 21S of the tail stock 21T
therebetween. The axis connecting the clamp 21C and the tail
spindle 21S is C-axis. The workpiece W is rotated by the spindle
motor 21 about C-axis and is ground by the grinding wheel 30.
During the grinding, an automatic sizing device (not shown) detects
the size of the workpiece W.
[0030] The wheel table motor 22 has a position sensor 22E which
detects the position of the wheel table TB2 along X-axis. The
spindle table motor 23 has a position sensor 23E which detects the
position of the spindle table TB1 along Z-axis. The spindle motor
21 has a position sensor 21E which detects the rotational angle and
the rotational speed of the workpiece W. Variety of sensors is
applied to the position sensors 21E, 22E and 23E, and encoders are
applied to the embodiment.
[0031] The CNC 40 comprises a CPU 41, a storage 42, an input/output
device 43 (keyboard, monitor, etc.), an interface 44, drive units
51-54 and etc. The CNC 40 controls the spindle motor 21, the wheel
table motor 22, the spindle table motor 23 and the wheel motor 24
depending on grinding data and grinding program stored in the
storage 42. The CPU 41 calculates command based on input data from
the input/output device 43, the program and the data stored in the
storage 42 and external input data through the interface 44, and
outputs the command through the interface 44. External input data
is signals of the position sensors 21E, 22E and 23E and the
automatic sizing device. The command is output to the drive units
51-54 in order to control the rotational angle/speed of the
workpiece W, the position of the wheel table TB2 along X-axis, the
position of the spindle table TB1 along Z-axis and the rotational
speed of the grinding wheel 30.
[0032] The drive unit 51 drives the spindle motor 21 which controls
the rotation of the workpiece W about C-axis. The drive unit 52
drives the wheel table motor 22 which controls the position of the
wheel table TB2 along X-axis. The drive unit 53 drives the spindle
table motor 23 which controls the position of the spindle table TB1
along Z-axis. The drive unit 54 drives the wheel motor 24 which
controls the rotation of the grinding wheel 30. The respective
drive units 51-53 gain the signals of the position sensors 21E, 22E
and 23E, compensate the command from the CPU 41 as feedback
control, and drive the spindle motor 21, the wheel table motor 22
and the spindle table motor 23. In FIG. 3, although the wheel motor
24 has no sensor, the wheel motor 24 may have a sensor for feedback
control.
[0033] [Examples of the Workpiece]
[0034] FIG. 8(A) and FIG. 8(B) show examples of the workpiece W
which has the cylindrical part(s) parallel to the rotational axis
(C-axis) and the end face(s) perpendicular to the rotational axis
(C-axis). FIG. 8(A) shows one example, the crankshaft W1 which has
plural crankpins (P1 to P4), crank journals (J1 to J5) and
shoulders. FIG. 8(B) shows another example, the transmission shaft
W2 which has plural cylindrical parts (E3 to E7) and shoulders.
[0035] [Grinding Method of One Cylindrical Part and One End Face
Adjacent Each Other]
[0036] The grinding method of the first embodiment is applied to
the workpiece W with one cylindrical part and one end face adjacent
each other (e.g., journal J1 and adjacent shoulder shown in FIG.
8(A), cylindrical parts E3, E4, E6 and E7 and adjacent shoulders
shown in FIG. 8(B) and/or etc.). The grinding method has a first
process shown in FIG. 6(A) and a second process shown in FIG. 6(B).
In FIGS. 6(A) and 6(B), hatching regions with horizontal and
vertical lines indicate grinding allowances ground by the R-part
30KM of the grinding wheel 30. Hatching regions with only
horizontal lines are ground by parts of grinding wheel 30 except
the R-part 30KM.
[0037] In the first process [1] as shown in FIG. 6(A), moving
backward in oblique direction of X-axis, the grinding wheel 30
removes the grinding allowance [1(0)] of the end face for rough
grinding of the end face. In the first process [1], the end face is
ground not by the R-part 30KM but by the side surface 30SM and the
back taper surface 30BM of the grinding wheel 30.
[0038] Next, the second process [2] takes place, see FIG. 6(B). The
second process [2] is separated to two steps which are finish
grinding step of the end face [2a] and rough grinding step of
cylindrical part [2b]. In the step [2a], the grinding wheel 30
moves forward along X-axis (perpendicular to C-axis) and removes
grinding allowance [2a(1)] for finish grinding of the end face. In
the step [2a], the end face is ground by a few regions of the
R-part 30KM corresponding to the grinding allowance. Further moving
forward along X-axis, the grinding wheel 30 reaches the cylindrical
part of the workpiece W and the step [2b] begins. In the step [2b],
continuously moving forward, the R-part 30KM removes the grinding
allowance [2b(1)], and the external surface 30FM removes the
grinding allowance [2b(0)] for rough grinding of the cylindrical
part. Thus the R-part 30KM and the external surface perform. The
finish grinding of the cylindrical part may take place in the step
[2b].
[0039] As described, the grinding allowances [2a(1)] and [2b(1)]
are ground by the R-part 30KM of the grinding wheel 30. The R-form
is transferred from the R-part 30KM to the region between the end
face and the cylindrical part so as the reduce stress
concentration.
[0040] With referring to FIGS. 1 and 6, the first embodiment will
be compared with the prior art about the amount of the grinding
allowances removed by the R-part 30KM. The substantial same amount
of the grinding allowance is removed in the step [2b] of the first
embodiment and in the step [A1b] of the prior art by the R-part
30KM.
[0041] In the step [2a] of the first embodiment and in the step
[A1a], the substantial same width of the R-part 30KM performs.
Because the allowance width of the prior art is larger than that of
the first embodiment at the rotational outward of the workpiece W,
the grinding allowance [A1a(1)] of the prior art is larger than
that [2a(1)] of the first embodiment.
[0042] Now, remaining processes (the first process [1] of the first
embodiment and the second process [A2] of the prior art) will be
compared. In the first process [1] of the first embodiment, the
grinding allowance [1(0)] is removed not by the R-part 30KM but by
the side surfaces 30SM and the back taper surfaces 30BM. However,
in the second process [A2] of the prior art, the R-part 30KM
performs.
[0043] Therefore, it is clear that the R-part 30KM removes smaller
amount of the grinding allowances in the first embodiment than in
the prior art. According to the grinding method of the first
embodiment, because it is possible to reduce the amount of the
grinding allowances removed by the R-part 30KM, the amount of
abrasion of the R-part 30KM is reduced. Therefore, the grinding
wheel 30 is able to keep its shape at the R-part longer than the
prior art so as to gain longer durability.
[0044] [Grinding Method of One Cylindrical Part and Two End Faces
Sandwiching the Cylindrical Part]
[0045] Second embodiment of the invention will be described with
reference to FIGS. 7 and 8. The grinding method of the second
embodiment is applied to the workpiece W with one cylindrical part
and two end faces sandwiching the cylindrical part, for example,
crank pins P1 to P4 and adjacent shoulders and/or crank journals J2
to J4 and adjacent shoulders shown in FIG. 8(A). In FIG. 7,
hatching regions with horizontal and vertical lines indicate
grinding allowances ground by the R-part 30KM of the grinding wheel
30. Hatching regions with only horizontal lines are ground by parts
of grinding wheel 30 except the R-part 30KM. Processes [1] to [6]
of the second embodiment are shown in FIG. 7.
[0046] First and second processes [1] and [2] of the second
embodiment are respectively similar to the first and second
processes of the first embodiment shown in FIG. 6. In the first
process [1], moving backward in oblique direction of X-axis, the
grinding wheel 30 removes the grinding allowance [1(0)] of one of
the end faces for rough grinding by using the side surface 30SM and
the back taper surface 30BM. In the second process [2], moving
forward along X-axis (perpendicular to C-axis), the grinding wheel
30 removes the grinding allowances [2a(1)] and [2b(1)] by the
R-part 30KM and the grinding allowance [2b(0)] by the external
surface 30FM. Thus the grinding wheel 30 grinds the one end face
for finish grinding and the cylindrical part for rough grinding.
The grinding allowances [1(0)], [2a(1)], [2b(1)] and [2b(0)] are
not shown in FIG. 7 but in FIG. 6 because of equivalency.
[0047] Third process [3] is a nongrinding stroke. The grinding
wheel 30 backwardly moves from C-axis (a little distance away from
the cylindrical part), and traverses toward the other end face.
[0048] Forth and fifth processes [4] and [5] are substantially the
same with the first and second processes [1] and [2]. In fourth
process [4], moving backward in oblique direction of X-axis, the
grinding wheel 30 removes the grinding allowance of the other end
face for rough grinding by using the side surface 30SM and the back
taper surface 30BM, as well as the first process [1]. In fifth
process [5], moving forward along X-axis (perpendicular to C-axis),
the grinding wheel 30 removes the grinding allowances by the R-part
30KM and the grinding allowance by the external surface 30FM, as
well as the second process [2]. Thus the grinding wheel 30 grinds
the other end face for finish grinding and the cylindrical part for
rough grinding.
[0049] Finally, in sixth process [6], traversing from the other end
face to the one end face in parallel direction of C-axis, the
grinding wheel 30 grinds the cylindrical part by using the external
surface 30FM for finish grinding.
[0050] As described, in the second embodiment, check-like hatching
regions in FIG. 7 indicate grinding allowances ground by the R-part
30KM of the grinding wheel 30. In consideration of the check-like
hatched grinding allowances ground by the R-part 30KM at the middle
of the cylindrical part between both end faces, the grinding
allowance [2b(2)] of the second embodiment in FIG. 7 is
substantially as large as that [A1b(2)] of the prior art in FIG. 2.
Thus, as well as comparison between the first embodiment in FIG. 6
and the prior art in FIG. 1, remaining check-like hatched grinding
allowances of the second embodiment is smaller than that of the
prior art. Compared to the prior art, the second embodiment is able
to reduce the amount of the grinding allowances removed by the
R-part 30KM. Therefore, because the amount of abrasion of the
R-part 30KM is reduced, the grinding wheel 30 is able to keep its
shape at the R-part longer than the prior art so as to gain longer
durability.
[0051] [Grinding Method of Only End Face(s)]
[0052] Third embodiment of the invention will be described with
reference to FIGS. 8(A) and 9. The third embodiment is applied to
the case that grinding is unnecessary to the crank journal J3 but
is necessary to the neighboring end faces T3L and T3R.
Specifically, respective fillet parts between the cylindrical part
J3 and the end faces T3L, T3R are previously processed by a fillet
roller so as to become concavities. In such case, it is usual that
the cylindrical part J3 is ground by another grinding machine. (The
third embodiment omits the explanation of grinding the cylindrical
part).
[0053] The end face T3L is ground by the processes [1] and [2] of
the second embodiment shown in FIG. 7, and similarly the end face
T3R is ground by the processes [4] and [5]. Finish grinding is done
by the processes [1], [2], [4] and [5]. By the way, because the
concavities reduce stress concentration, it is unnecessary to
transfer the R-form from the R-parts 30KM of the grinding wheel 30
to the end faces T3L and T3R. Thus it is unnecessary for the
grinding wheel 30 to have the R-parts 30KM so that right angle may
be applied to the boundaries between the external surface 30FM and
the side surfaces 30SM.
[0054] According to the above described embodiments, the grinding
machine 1 moves the grinding wheel 30 to/away from the workpiece W
along X-axis, as shown in FIGS. 3 and 4. However, because relative
movement is needed between the grinding wheel 30 and the workpiece
W along X-axis, the workpieces W may move to/away from the grinding
wheel 30 along X-axis.
[0055] Similarly, although the workpiece W moves along Z-axis in
the embodiments, the grinding wheel 30 may move along Z-axis. Thus
the grinding wheel 30 relatively moves to the workpiece W along
Z-axis.
[0056] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is thereby to be understood that within the scope of the appended
claims, the present invention may be practiced otherwise than as
specifically described herein.
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