U.S. patent number 3,665,648 [Application Number 05/075,842] was granted by the patent office on 1972-05-30 for grinding apparatus.
This patent grant is currently assigned to Yugen Kaisha Yamanaka Seisakusho. Invention is credited to Sadajiro Yamanaka.
United States Patent |
3,665,648 |
Yamanaka |
May 30, 1972 |
GRINDING APPARATUS
Abstract
A grinding apparatus which is so constructed that three
workholders are rotatably mounted on a turn table in equally spaced
relation peripherally of said turn table to be intermittently
shifted from one to another of three positions consisting of an
inoperative position and a first and second working positions. Two
grinding mechanisms are arranged exterior of said turn table
adjacent said first and second working positions respectively. The
table is operative in such a manner that a workpiece mounted on one
of said workholders in said inoperative position is carried thereon
to said first working position where it is roughly ground and then
to said second working position where it is subjected to a
finishing grinding and then back to said inoperative position to be
removed from the apparatus, the intermittent rotation of said turn
table being controlled by a detecting device which detects the
amount of the workpiece ground by way of a master which is ground
concurrently with said workpiece.
Inventors: |
Yamanaka; Sadajiro (Chigasaki,
JA) |
Assignee: |
Yugen Kaisha Yamanaka
Seisakusho (Chigasaki-shi, Kanafawa-ken, JA)
|
Family
ID: |
14311173 |
Appl.
No.: |
05/075,842 |
Filed: |
September 28, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Dec 18, 1969 [JA] |
|
|
44/101837 |
|
Current U.S.
Class: |
451/292;
451/12 |
Current CPC
Class: |
B24B
7/06 (20130101) |
Current International
Class: |
B24B
7/00 (20060101); B24B 7/06 (20060101); B24b
017/00 () |
Field of
Search: |
;51/134,165.77,165.78 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Whitehead; Harold D.
Claims
I claim:
1. A grinding apparatus comprising a frame, a turn table rotatably
mounted on said frame, three disc-shaped workholders rotatably
mounted on said turn table in equally spaced peripheral relation on
said turn table, two grinding mechanisms arranged exterior of said
turn table in spaced relation from said turn table, means for
rotating said turn table intermittently in such a manner that one
of said workholders may be held stationary in position
corresponding to one of said grinding mechanisms and another one in
a position corresponding to the other grinding mechanism, means for
rotating each one of said workholders in a path of movement from
the position corresponding to one of said grinding mechanisms to
the position corresponding to the other grinding mechanism and
holding it stationary in the other position, a master provided
adjacent each of said workholders and operatively connected to said
workholder to be rotated thereby, each of said grinding mechanisms
including a grinding wheel arranged to grind a workpiece on the
workholder and said master concurrently, and means for detecting
the amount of said master ground by said grinding wheel and
emitting a signal to stop the grinding operation.
2. The apparatus of claim 1 including magnetic means associated
with said workholders to retain the workpiece thereon.
3. The apparatus of claim 1 in which the turn table is circular and
the workholders follow an arcuate path in movement from one
position to the next.
4. The apparatus of claim 3 in which said turn table is horizontal
and said grinding mechanisms are located vertically above the turn
table.
5. The apparatus of claim 1 including means to move said grinding
wheels in a rotary direction in a plane parallel to said
workholders.
6. The apparatus of claim 5 in which the grinding wheels are
cup-shaped.
7. The apparatus of claim 1 including a two speed means for moving
the grinding mechanism toward the workpiece with a high speed for
setting up operation and a low speed for grinding.
Description
The present invention relates to a grinding apparatus for a
workpiece and has for its object the provision of such a grinding
apparatus which is capable of grinding a workpiece more efficiently
and finishing the same with higher accuracy than conventional
apparatus.
An embodiment of the present invention will be described
hereinafter with reference to the accompanying drawings, in
which:
FIG. 1 is a plan view showing the overall arrangement of the
grinding apparatus according to the present invention;
FIG. 2 is a perspective view of a portion of the apparatus;
FIG. 3 is a cross-sectional view of a turn table driving
mechanism;
FIG. 4 is a plan view briefly showing the arrangement of a slip
ring for controlling the rotation of a grinder;
FIG. 5 is a plan view showing the power transmitting arrangement of
the turn table driving mechanism;
FIG. 6 is a cross-sectional view showing a master driving mechanism
of a measuring device;
FIG. 7 is a plan view showing the arrangement the turn table,
workholder and master driving mechanism;
FIG. 8 is a cross-sectional view of the measuring device;
FIG. 9 is a plan view of the measuring device looking in the
direction of the line IX--IX of FIG. 8;
FIGS. 10 and 11 are a side view and a plan view respectively,
showing in detail a portion of the measuring device;
FIG. 12 is a cross-sectional view of the entire grinding
mechanism;
FIG. 13 is a cross-sectional view showing a driving device for the
grinding mechanism; and
FIG. 14 is a cross-sectional view taken on the line XIV--XIV of
FIG. 13.
FIG. 15 is a schematic wiring diagram of the control circuit of the
measuring device.
OUTLINE OF THE APPARATUS
The apparatus of the instant invention comprises a turn table
assembly T, a left hand grinding mechanism LG, a right hand
grinding mechanism RG and a coolant supply mechanism C (FIG. 1).
The turn table assembly T includes a turn table 10 rotatably
arranged in a horizontal plane and three workholders 11 arranged in
substantially the same direction as the turn table in equally
spaced relation and rotatable relative to said turn table. The
workholders 11 are made of a magnetic material and hold a workpiece
(not shown) thereon under the magnetic force thereof. Two grinding
mechanisms LR,RG are arranged in positions corresponding to two of
the three workholders 11, i.e. positions 11a, 11b. Each of the
grinding mechanisms has a cup-shaped grinding wheel 12 supported in
opposed relation to the upper surface of the workholder 11 (FIG. 2)
and the grinding wheel is rotatably driven in contact with the
workpiece, retained on the workholder 11 to grind said workpiece.
The grinders 11 are rotatably driven when they are in the positions
corresponding to the grinding mechanisms LG, RG, or in the working
positions, and are held inoperative in the other position, i.e. the
position indicated by 11c in FIG. 1. The workpiece is mounted on
the workholder while in the inoperative position 11c and then the
turn table 10 is rotated in a clockwise direction as viewed in FIG.
1 to place that workholder in a first working position indicated by
11a, where it is driven. At the same time, the grinding wheel 12 of
the grinding mechanism LG is lowered to grind the workpiece. In the
first working position, the workpiece is ground roughly. Then, the
turn table is further rotated in a clockwise direction and the
workpiece is brought to a second working position indicated by 11b,
where it is subjected to a finishing grinding. Thereafter, the turn
table 10 is further rotated in a clockwise direction and the
grinder is shifted to the inoperative position indicated by 11c,
where the finished workpiece is demounted from the workholder and a
new workpiece is mounted on the workholder 11.
In the apparatus of this invention, a measuring device or master 82
is provided adjacent each workholder 11. This master 82 is a
cylindrical body made of such a material, for example, as bakelite,
and is driven in association with the workholder. In the grinding
operation, the grinding wheel 12 in contact with the workpiece is
also held in contact with the master 82 and grinds said it at the
same rate as the workpiece. A detector element 109a of an electric
micrometer 109 is held in contact with the upper edge of the master
82 to detect the point when the master has been ground by a
predetermined amount and thereby to control the interruption of the
grinding operation and shifting of the workholder 11 to the next
grinding step. Cooling water is supplied to the grinding portion
from the cooling device C throughout the grinding operation.
Turn Table Assembly
The turn table 10 of the turn table assembly T is secured to a main
vertical rotary shaft 15 at its center by means of a plurality of
bolts 16' (FIG. 3). A worm wheel 16 is fixedly mounted on the lower
end of the main rotary shaft 15 as by key 17, and a worm 18 is in
meshing engagement with the worm wheel 16. The main rotary shaft 15
is driven by the rotation of the worm 18. A hollow cylindrical
rotary sleeve 19 is provided concentrically around the lower
portion of the main rotary shaft 15, with the upper and lower ends
thereof rotatably mounted on said main rotary shaft through
bearings 20, 21 respectively. The exterior of the rotary sleeve 19
is surrounded by a hollow cylindrical fixed sleeve 22 which is
secured to a frame F. The rotary sleeve 19 is rotatably supported
on the fixed sleeve by bearings 23, 24. A gear 25 is fixed to the
upper end of the rotary sleeve 19 by a pin 26 and a bearing 27 is
interposed between the underside of the gear 25 and the upper edge
of the fixed sleeve 22. Further, a bearing 28 is interposed between
the lower end portion of the main rotary shaft 15 and the fixed
sleeve 22. A worm wheel 19a is formed at the lower end portion of
the rotary sleeve 19, which is in meshing engagement with a worm
29. The rotary sleeve 19 is rotated by the rotation of the worm
29.
A work spindle 30 to drive the workholder 11 is arranged in
parallel to the main rotary shaft 15 and spaced therefrom in the
radial direction of the turn table 10. A disc-shaped supporting
plate 31 is fixed to the top end of the spindle 30 as by bolts 32
and rotatably supported by the upper surface of a spindle case 33,
fixed to the turn table 10, and an annular projection 33a formed
thereon. The spindle case 33 has a cylindrical portion 33b
extending downwardly so as to surround the entire length of the
spindle 30. The cylindrical portion 33b is formed therein with an
opening 33c on the side facing the main rotary shaft, through which
the gear 25 extends into the spindle case 33. On the spindle 30 is
rotatably mounted by a bearing 35 a gear 34 which meshes with the
gear 25. A spline part 36 is fixed to the underside of the gear 34
by means of a bolt 37 and a clutch element 38 is in spline
engagement with said spline part 36. A clutch element 39
co-operating with the clutch element 38 is fixed to the spindle 30
by means of a key 40 and electromagnetic coil 41 is disposed within
the clutch element 39. The coil 41 is secured by means of a bolt 44
to an annular body 43 which is rotatably mounted on the spindle 30
through a bearing 42. The annular body 43 is non-rotatably fixed to
the spindle case 33 by means of a stop pin 45. Therefore, when the
coil 41 is excited, the clutch element 38 is attracted towards the
clutch element 39 and brought into engagement therewith, so that
the drive of the main rotary shaft is transmitted to the spindle 30
through the gear 34 and the clutch elements 38, 39. As stated
previously, the workholder 11 is made of a magnetic material and
hence capable of holding the workpiece magnetically.
As shown in FIG. 3, an annular body 46 made of an insulating
material is fixed to the outer surface of the fixed sleeve 22 as by
a pin 47, and a ring 48, made of an electrically conductive
material, is fitted around said annular body 46. The ring 48, as
shown in FIG. 4 is split into a portion 48a which extends along
about three-fourths of the entire circumference of the annular body
46 and a position 48b which extends along the remainder of said
circumference. The portion 48a is connected to a power source
through a conductor not shown. A brush 50 is fixed to the spindle
case 33 by means of a bracket 49 as shown in FIG. 4, which will
slide on the ring 48 in contact therewith. The brush 50 is
connected to the coil 41 through a suitable conductor (not shown).
The arrangement is such that, when the brush 50 is in contact with
the portion 48a of the ring 48, the coil 41 is excited to drive the
spindle 30, whereas when the brush 50 is in contact with the
portion 48b of said ring, the current supply to the coil 41 is
interrupted and hence the spindle 30 stops rotating. The point
where the brush 50 is brought into contact with the portion 48b of
the ring 48, corresponds to the inoperative position 11c of the
workholder mentioned previously.
A mechanism for transmitting rotation to the worms 18 and 29 is
shown in FIG. 5. The shaft 51 of the worm 18 is horizontally and
rotatably supported by a pair of bearings 52, 53 and has a pulley
54 connected to one end thereof. A motor 55, provided outside the
column of the grinding mechanism RG to be described later, drives a
pulley 57 through a reduction gear 56 and the drive of the motor 55
is transmitted to the worm shaft 51 through a belt 58 engaged
around the pulley 57 and the aforesaid pulley 54. The shaft 59 of
the worm 29 is rotatably supported by a pair of bearings 60, 61 and
has a pulley 62 connected to one end thereof. A motor 63, provided
outside of the column of the grinding mechanism LG to be described
later, drives a pulley 65 through a reduction gear 64 and the drive
of the motor 63 is transmitted to the worm shaft 59 through a belt
66 engaged around the pulley 65 and the aforesaid pulley 62. The
motor 55 is operated by an instruction from the measuring device
109 as will be described later, and set in motion when the
workpiece has been ground to a predetermined dimension, to cause
rotation of the turn table 10. An index means may be provided as
required, to determine the position of the table 10.
Measuring Device
A master 82 is provided adjacent each workholder 11. As shown in
FIG. 6, its drive includes a hollow cylindrical drive shaft 69
having a gear 67 fixed on the lower end thereof by a key 68, and a
center shaft 70 extending through the axial bore of said drive
shaft 69. The center shaft 70 and the drive shaft 69 are combined
by a key groove 70b and a key 71' slidably received in said key
groove, in such a manner that they are longitudinally slidable
relative to each other but rotate all together. As shown in FIG. 3,
a gear 72' is fixedly mounted on the spindle 30 above the gear 34,
and this gear 72' turns with the aforesaid gear 67 through an
intermediate gear 73' (FIG. 7). Therefore, when the spindle 30 is
driven, the drive shaft 69 and the center shaft 70 of the measuring
device 13 are driven concurrently. Exterior of the drive shaft
there is provided an inner sleeve 73 through a roller bearing 71
and a ball bearing 72, and an outer sleeve 74 is axially slidably
provided around the inner sleeve 73. The sleeve 74 is formed with
an inward flange 74a at the upper end thereof and a bearing 75 is
interposed between said flange 74a and an annular flange 70a formed
on the center shaft 70 adjacent the upper end thereof. A support
disc 76 is connected to the upper end of the center shaft 70 by a
key 77 and fixed thereto by means of a nut 78, for rotation
therewith. A bearing 79 is interposed between the support disc 76
and the upper end of the outer sleeve 74. A master supporting
member 80 is fixed on top of the support disc 76 by means of a bolt
81 and a cylindrical master 82 is fixed on top of the master
supporting member 80 by a retainer ring 83 and a cap 84. The cap 84
is secured to the master supporting member 80 through threadable
engagement between it and an externally threaded stud 80a provided
centrally of the upper surface of the master supporting member 80.
The master 82 is preferably made of such a material as bakelike.
When the gear 67 is driven, the master supporting assembly
constructed as described above is rotated, with the drive shaft 69,
the center shaft 70, the support disc 76, the master supporting
member 80, the master 82, the retainer ring 83 and the cap 84 as an
integral unit.
The master supporting assembly described above is supported by
axially slidably fitting the outer sleeve 74 in a supporting
bracket 85 which is fixed to the frame F. The outer sleeve 74 is
formed with a axial key groove 74b in the outer peripheral surface
thereof, and a key 86 fixed to the bracket 85 is received in said
key groove. Further, external threads are formed in the lower
portion of the outer peripheral of the outer sleeve 74 and a gear
87 is mounted on said outer sleeve, with internal threads of the
former in engagement with said external threads of the latter.
Therefore, when the gear 87 is rotated, the outer sleeve 74 and
hence the master 82 is elevated. A lock screw 88 is extended
horizontally through the wall of the supporting bracket 85, with
the inner end thereof engaging the external threads on the outer
surface of the outer sleeve 74 to lock the vertical position of
said outer sleeve. The gear 87 is rotatably supported by bearings
89 provided on the upper and lower surfaces thereof and can be
rotated by a mechanism including a manual adjusting wheel 90. The
manual adjusting wheel 90 is fixed on a vertical shaft 93 by means
of a key 94, which vertical shaft 93 is supported by a supporting
plate 91, fixed to the frame F, through a bearing 92. The vertical
shaft 93 has a gear 95 fixedly mounted on the lower end thereof by
a bolt 96, and the gear 95 is meshing with the gear 97 through an
intermediate gear 97.
Detector Assembly
The detector assembly is provided in combination with each one of
the left and right hand grinding mechanisms LG, RG. As shown in
FIG. 1, each detector assembly includes a vertical post 98 (FIG. 8)
fixed to the frame F exterior of the turn table, and a cylindrical
housing 101 is rotatably mounted on the vertical post 98 to
surround the same, through bearings 99, 100. A supporting cylinder
102 is fixed to the upper end of the cylindrical housing 101 by a
bolt 103, and an arm 105 is connected to the outer surface of said
supporting cylinder 102 through a bracket 104. The post 98 extends
through the supporting cylinder 102, and a lock screw 106 is
mounted on a threaded portion 98a at the top end thereof. The lower
surface of the lock screw 106 acts on the upper edge of the
supporting cylinder 102 through a washer 107, to hold the housing
101 and the supporting cylinder 102 against rotation. A handle 108
is provided on the lock screw 106 and, by loosening the lock screw
106 by said handle, the housing 101 and the supporting cylinder 102
are rendered rotatable relative to the post 98.
The arm 105 has a detector such, for example, as an electric
micrometer 109 fixed to one end thereof, and a detector operating
bracket 110 is fixed to the detector 109 below the arm 105. The
bracket 110 is formed with a flange extending downwardly from one
end thereof and a horizontal shaft 112 is rotatably fitted to said
flange. A lever 113 and a lift plate 114 are connected to one end
and the central portion of the horizontal shaft 112 respectively. A
tension spring 115 has its lower end anchored to one end of the
lever 113, with the upper end thereof anchored to a rod 118 which
is connected to a vertically movable head 116 of the grinding
mechanism to be described later, through a bracket 117 in such a
manner that the vertical position thereof may be adjusted. The free
end of the lift plate 114 is located beneath the lower surface of a
movable portion 109a of the micrometer 109. Thus, when the
vertically movable head 116 moves upwardly, the free end of the
lift plate 114 is elevated, pushing the movable portion 109a of the
micrometer 109, so that the movement of the master 82 will not
interfer with micrometer 109 during rotation of the turn table. The
head 116 is lowered in the grinding operation and, therefore, the
lift plate 114 is held away from the micrometer 109 as shown in
FIG. 10. Reference numeral 119 designates a stop pin to define the
lowered position of the lever 113 and hence of the lift plate 114.
During the grinding operation, the tip end of a detecting needle of
the micrometer rests on the upper surface of the master 82, to
detect the amount of the master and, therefore, the amount of the
workpiece which has been cut.
Grinding Mechanism
The apparatus of the instant invention is provided with two
grinding mechanisms LG, RG but, since both grinding mechanisms are
identical in construction, only one of them will be described
herein with reference to FIGS. 12, 13 and 14.
The grinding mechanism includes a head member 121 vertically
slidably mounted in a column 120 fixed to the frame F, and a nut
member 123 is fixed on the head member 121 by a bracket 124. The
nut member 123 is in threadable engagement with a threaded drive
shaft 122 vertically rotatably extending through the column 120. It
will, therefore, be seen that the head member 121 can be moved
vertically by rotating the threaded drive shaft 122. The shaft 122
is driven at two different speeds, i.e., a high speed and a low
speed, by two systems, i.e. a quick feed feed mechanism and a
grinding feed mechanism, respectively. The quick feed mechanism
consists of a worm wheel 126 which is rotatably mounted on the
lower end of a shaft 122 and coupled therewith by an
electromagnetic clutch 125, and a worm 128 which is mounted on the
output shaft of a motor 127 and adapted to engage said worm wheel
126. The grinding feed mechanism includes a grinding feed motor 129
(FIG. 13). The output shaft of the motor 129 is connected to a
shaft 132 through gears 130, 131. The shaft 132 has a worm 133
formed at one end thereof, which meshes with the worm wheel 135 on
an intermediate shaft 134 (FIG. 14). Intermediate shaft 134 has a
worm 136 which meshes with a worm wheel 138 on a shaft 137. The
worm wheel 138 is rotatably mounted on the shaft 137 and coupled
therewith by an electromagnetic clutch 139. On one end of the shaft
137 is fixedly mounted a bevel gear 140 which meshes with a bevel
gear 141 fixedly mounted on the shaft 122. Thus, when the clutch
139 is excited, with the motor 129 in motion, the shaft 122 is
driven at the low speed, that is, the grinding feed speed. Further,
a handle 142 is provided at the outer end of the shaft 137. By
rotating the handle 142, the head member can be manually moved up
and down. Further, on the bracket 124 supporting the nut 123 a
second nut 143 is provided which is in threadable engagement with
the shaft 122, and a worm wheel 144 is formed on the outer
periphery of said nut 143, which meshes with an adjusting worm 145.
Thus, it will be understood that, by rotating the adjusting nut
145, the nut 143 is rotated and the back-lash between the first nut
123 and the threads of the shaft 122 can be eliminated by the
slight rotation of said nut 143. A balance weight 149 is provided
on the head member 121 by means of a wire 148 which is engaged
around pulleys 146, 147 provided on the column 120.
A motor 150 is fixed on the upper surface of the head member 121
and a pulley 151 is mounted on the output shaft of said motor. The
pulley 151 is operatively connected with a pulley 153 through a
belt 152, which pulley 153 is fixed on the upper end of a rotary
shaft 155 rotatably received in a cylindrical vertical bore formed
in the head member 121. The cup-shaped grinding wheel 12 is fixed
to the lower end of the rotary shaft 155 by a suitable means. The
grinding wheel 12 is positioned above the workholder 11 and the
master 82 of the measuring device in the working position.
Therefore, when the motor 150 is set in motion, the grinding wheel
12 is rotated at the grinding speed, whereby the workpiece on the
workholder 11 can be ground.
Operation
In operating the apparatus of the present invention, a workpiece is
mounted on the workholder in an inoperative position 11c, which is
capable of holding the metallic workpiece thereon as it is made of
a magnetic material. Here, the turn table 10 is turned in a
clockwise direction as viewed in FIG. 1 and the workholder 11, with
the workpiece mounted thereon, is shifted to below the grinding
wheel 12 of the grinding mechanism LG, that is, the first working
position. Immediately before reaching the first working position
the workholder 11 is caused to rotate by the mechanism described
previously with reference to FIGS. 3 and 4. When the workholder 11
has reached the first working position, the rotation of the turn
table 10 is stopped and the head member 121 of the grinding
mechanism LG is lowered and the grinding wheel 12 is brought into
contact with the workpiece to grind the same.
The head member 121 is lowered in two steps. Namely, the head
member is lowered by the motor 127 at a relatively high speed until
immediately before the grinding wheel 12 contacts the workpiece and
then is lowered by the motor 129 at a relatively low speed as a
result of the electromagnetic clutch 125 being demagnetized and the
electromagnetic clutch 139 being excited. As stated previously, the
grinding wheel 12 grinds the workpiece and the master 82 of the
measuring device concurrently. The amount of the master 82 ground
is detected by the detecting device and, when the amount has
reached to a predetermined value, the shaft 122 is driven in a
reverse direction in response to an electric signal from the
electric micrometer of the detecting device, to lift the head
member 122. The control circuit to accomplish this reverse
direction is shown in FIG. 15. When the master is sufficiently
ground, a microswitch in micrometer 109 closes, actuating a
solenoid which in turn actuates a reversing switch feeding motor
127. After the head is lifted, the turn table 10 is rotated and the
workholder 11 is shifted to the second working position, i.e. a
position corresponding to the grinding mechanism RG, with the
roughly ground workpiece thereon, where the workpiece is subjected
to a finishing grinding.
The apparatus of the invention is particularly adapted for use in
grinding a number of small-sized workpieces on the grinder. In a
case where it is impossible to measure the amount of the workpiece
ground by contacting the electric micrometer directly with the
workpiece, this problem can be solved by providing a master
separate from the workpiece. In addition, the grinding is effected
in two stages, i.e. by a rough grinding operation and a finishing
grinding operation, and these grinding operations can be carried
out concurrently by two grinders. Yet further, in the process of
the grinding operations, the finished workpiece can be removed from
and a new workpiece can be mounted on the workholder which is
located in an inoperative position. Thus, the grinding operation
can be carried out in a highly efficient manner.
* * * * *