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Патент USA US2131327

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Sept. 27,‘ 1938.
Filed larch 13, 1937
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Patented Sept. 27, 1938
12 Claims.
The present invention relates toa live center
for tail stocks in metal ‘working machines.
The invention is applicable to ‘any type of
machine in which a pieceof work is'supported
5 between centers, and is rotated by. driving means,
during which rotation 'a metal working operation
is performed upon the'piece of work;
The invention comprises essentially ‘a ‘live cen
ter assembly, in which the center that'supports
10 the work is adjustable transversely of the _as
sembly in order 'to support the work “eccentrica'lly
‘a live center constructed in accordance with the
presentinvention. -
Figure ‘2 is a plan View, the piston being shown
in ‘section.
1 _
Figure 3'is 'anelevation of the front face of the ~#5
center assembly.
Figure 4 is asectional view on'the line 4--4 of
‘ Figure '2.
Figure 5 is a sectional view of the center as
Figure '6 is a sectional view on the line 6—6 of
upon its axis of rotation. '
Figure 5.
One object of the‘inventi'on is ‘to provide a
live center assembly having means whereby the
Describing the drawing more particularly, and
referring ?rst to ‘Figures 5 and 6, the live center
15 center may be ‘adjusted to rotateeccentrically
of the assembly.
Another object 'is'to provide micrometer ad
justment means, whereby the ‘degree ‘of "eccen
tricity may be controlled.
(c1. 82-33)
assembly includes ars'upporting element 1 having-~15
‘the form of ‘a, standard taper, but which may
_be of any desired con?guration to fit the tail
stock ‘of a machine. At its forward end the
supporting member 1 ‘may carry ‘a ?ange 8 ex
Still ‘another object is to provide means "for
insuring the turning of the center ‘with ‘the ‘work
tending annularly, and forming the rear walk/‘120
(of "a bearing enclosure 9. Extending forwardly
in order to cause the r'otarymot'i'on ‘of the ~work
‘centrally of the ?ange 8 ‘is ‘a stud III that sup
ports ‘one element ll of ‘a ball race I2, the ele
to be eccentric..
Still another objectfis to provide "supporting
means for the end of the‘ work engaged by
the center in a yielding manner to permit ec
ment 11 being advantageously mounted on the
stud I0 ‘b-y'a press ?t.
Revolubly carried by the stud Ill and bear
centric rotation.
ing member H is a head l3 comprising an an
nular cup-like member 14 having a frontwall
The ?eld to which theinvention is particu
larly directed, and in connection with which it ‘I5 ‘and circular side wall 16. Theside wall l6
"carries internally a ball race member I‘! advan-‘s30
30 was developed, is that of grinding pistons.
In modern internal combustion engines, and vtageously press ?tted therein and cooperating
especially automobile engines, 'it'is customary to with the member H and balls I 8 to revolvably
use pistons that are not truly ‘cylindrical. The support the head l3 upon the stud ID. The side
pistons that are used ‘are ‘what ‘are ‘termed in ‘wall l6 has edges formed ‘to cooperate with the
edges of ‘the wall ‘8 to form a grease seal to ex-; 535
35 the industry as cam-ground pistons, which means
that they are slightly oval in form, particularly "elude dirt ‘and to maintain a supply of lubricant
within the enclosure '9. A grease port l9 ‘may be
adjacent their tops, this being to v'all'o'w for un
equal expansion due to the'pini‘supporting struc
-It will be ‘seen from the "structure so far dis
ture carried within the pistons._
In manufacturing pistons it ‘is customary to closed that the head I3 is concentrically re- @40
form the pistons in ‘the ‘form of a true ‘cylinder, 'volv'a'ble’upon the stud ‘I0. In order'to provide
and then by a grinding operation, bring the for ‘adjustable eccentric rotation, the following
center structure ‘is provided.
pistons to the requisite slightly oval "form. ‘Here
'The front wall l5 "of the‘ head I3 is provided
tofore this grinding operation has been'performed
with a transverse dovetailed mortise 20, the '45
45 by highly complicated and expensive grinding
machines. By means of the ‘present invention “said ‘mortise passing through the center of
this grinding operation may 'be performed by rotation of "the ‘head. \Advantageously the mor
any ordinary grinding machine. In addition to tise may vbe formed in a projecting rib-like ex
the above described use, the invention is ‘applica ”tension 2! formed integrally with the wall l5,
"and ‘having ‘at each side a shoulder 22.
ble to turning, or any other ‘field o‘f'm'et‘al work
'Slidably mounted within the ‘mortise 20 and
ing where it is desired to "form "an ‘eccentric '
shaped to closely engage the sides of the mortise
is a carriage vmember :233 preferably substantially
In the accompanying drawing:
“equal in length "to the diameter of the front Wall
Figure 1 is an elevation ‘showing "schemati
*ca‘lly a piston supported ‘between an "adapter and 115. :Themember'2'3 carries at its central portion 55
a cone-shaped center 24 that projects forwardly
of the front face 25 of the rib 2|, and that is de
signed to engage and support the center of the
piston or other work to be operated upon. An ad
lusting screw 26 controls the position of the car
riage 23 and therefore of the center 24. The
screw 26 is threaded into a bore 21 in the wall I 5
of the head, the bore being positioned closely ad
jacent the inner surface of the mortise 20. Pref
10 erably the threads of the bore 21 andof the screw
26 are of a micrometer type, so that longitudinal
movement of the screw will bear a de?nite‘ rela
the center 24 and the head stock 38 of a grind
ing machine, the head stock being provided with,
an adapter 39 equipped with a driver 40 in ac
cordance with standard practice. The driver“
extends forwardly from the adapter and engages 5
one of the pin bosses 4| of the piston to rotate
the piston.
Assuming that it is desired to eccentrically
grind the top portion of the piston, as shown in
‘FigureHZ, the screw 26 isturned to give the proper 10
degreevof eccentricity of rotation to the piston, as
indicated by the‘ scale 29. With the grinding
tion to its amount of rotation. The screw 26 has _ .instrumentality of the grinder set at the proper
an enlarged head 21a that overlies and engages‘
15 that
the end
the carriage
of the23.
It will
in a be
to ,
cause the head to travel toward the center of
the assembly the enlarged head 21a. bearing upon
the end of the carriage 23, will cause the car
20 riage to move in a direction of motion of the
screw. Preferably the screw is provided with, a
pointer, as at 28 in Figure 2, and the wall of the
head is provided with a scale 29, so that a deter
mined adjustment may be easily made. Upon
125 the opposite side of the head is mounted a, back
ing screw 30 threaded into the wall] l5, and hav
ing an enlargedhead 3| that contacts the oppo
site end of the carriage 23.
By means ,of this
screw, the carriage may be secured in adjusted
.30 position and by tightening the vscrew, the car
riage will be tightened against the head 21a of
the screw 26, insuring that the scale reading is
accurate. A scale 29a may also be provided in
the front face of the assembly.
distance, the machine is started, and as the pis
ton rotates eccentrically, the grinder will operate 15
upon a portion of its surface at each revolution.
"'When the grinding operation has been completed
uponone side of the piston, the piston is reversed
in'its position with relation to the center so that
the opposite side may be ground. The reversing 20
operation may be accomplished by holding the
head I3 ‘against'rotation, and by hand turning
“the. head, stock 38in adirection reverse to its
normal. direction of rotation, or it may be ac
_complishe_d..]oy holding’ the, piston and turning 25
l the head,,l.3>in a forward direction. In either"
method thefsh'arp edges of the ?ngers will slide
easily over.fthe top surface of the piston. The
reverse motion may be imparted to the'head stock
from any suitable part of the machine that isugo
accessible to thehand of the operator.
In order that the grinding may take place at
theproperpoint on the surface of the piston, the
center of the head of the screw 26 is lined up with
the center of'the pin hole 42 of the piston, and.;,_35
upon reversal of the piston, as above described,‘‘"
From the foregoing description, it will be ap
parent that rotation of the head l3 upon the stud
ID will cause the center 24 to revolve in a plane
‘the opposite pin holeis lined up with the screw
tary manner around the center of rotation of the 26. The head of the screw 26 indicates the por
assembly, assuming that the carriage has been tion, that during the rotation of the piston, is
-40 moved to place the center in a position removed farthest ‘from the centerof rotation of the head._,40
vfrom the center of rotation of the assembly. ,It‘ . Where ,it- isv desired to grind oif a portion of a
will also be apparent that the circular rotation ,-piston other than that adjacent the pinhole, the
of the center will cause a piece of work held be
portion to be operated upon may be easily selected
tween the center and a driving center of a ma _ by lining. it up withthe screw 26.
' , Referring further to Figures 1 and 2 it is some-. 45
45 chine, to rotate in an eccentric manner.
In order to insure that the desired eccentric , times necessary thata piston be cam-ground only
rotation will occur, instead of concentric rota
in its uppermost portion, while sometimes it is
tion between centers that are not in line, it is _ necessary to, cam-grind the piston throughout its
necessary to insure that the head I 3 rotates upon length. Where only the upper portion is intended
the stud l0. Means are provided for insuring to be ‘ground, the, procedurev as above described, 50
rotation of the head l3 by the rotating work.
This means is provided in the form of spring
?ngers 32 mounted upon the front face of the
wall I5 at either side of the rib member 2|, and
55 abutting the shoulders 22 thereof. The spring
?ngers include end portions 33 that lie closely
adjacent the surface, and which are held by
screws 34 having heads that overlie these end
portions. The ?ngers proper are bent outwardly
60 and extend angularly forwardly from the por
is correct.
Where, however, it is necessary to
, cam-grind a piston throughout its length it be
comes necessaryto rotate the complete piston,
. as‘ distinguished from one end of the piston, ec
Vcentrically. In Figure 1 the method of doing this, 55
- isvillustrated. A piece of shim stock or other ma
‘ terial=of proper thickness, as illustrated at 42 in
, Figure 1 is inserted’ between the surface of the
adapter 39 and the inner surface of the piston.
- Where it is desired togrind off the same amount 60
tions 33 and in a direction, opposite to that in _ of the piston throughout its length and along one
which the head rotates, and terminate in sharp
cornered edges 35.-v Thesharp corners of the
edges 35 engage the surface of the work, as shown
in Figures 1 and 2, with sufficient security to in
sure that the head l3 rotates upon the stud I0.
Inasmuch as the rotation of the work is eccen
side, the material 42 will be selected of the same
width as the amount that the center 24 is moved
off center. It will be readily realized that dif
ferent degrees of taper in the ground area may 65
be provided by relating the thickness of the ma
.terial 42 to the adjustment off-center of the
tric, the distance between the face of the work, center 24._' 7
as the .top surface 36 of the piston 37, shown in
By use of this center assembly, any sort of co
Figures 1 and 2, and the front surface of the centric operation may be performed in a machine 70
head, constantly varies. The resilient nature of ,in which the work is supported between centers.
the spring ?ngers 32 permits this variation.
While it has been described as applied to a ma
In Figures 1 and 2 is illustrated, somewhat chine for grindingpistons, it will be readily ap
schematically, the method of use of the center parent that it _may be-applied to other metal
assembly. A piston 31 is shown mounted between _ working machines in which the work is revolved._ 75
its use, an ordinary rotary metal working ma
chine may be used for operations that heretofore
mortise extending transversely across its front
end and passing through the center of rotation, a
carriage member slidably engaged in the mor
tise, means for securing the carriage against
movement in the mortise, a forwardly extending
center mounted upon the carriage, and spring
required the use of complicated and highly spe
cialized machines.
?ngers mounted at either side of the mortise, the
said ?ngers each extending angularly forward of
The assembly provides for controlling the ec
centricity given to the rotation of the work with
the utmost precision. The assembly is simple
and relatively inexpensive to construct, and by
It is an essential feature of the invention that
the adjustment of the center with respect to the
center of rotation be located forwardly of the
bearing assembly that permits turning of the
head with respect to the stationary portion of
the assembly, because an adjustment located
rearwardly of the bearing assembly would result
merely in two out-of-line centers, by means of
which a tapered piece of work could be produced,
but which would not cause eccentric rotation of
the work. Similarly a dead center adjustable to
a position out of line with the driving center will
result in a tapered piece of work, rather than an
eccentric one because the work rotates upon a
the face in a direction opposite the direction of
motion of the machine and forwardly of the front
face of the head to a point to be engaged by work
in the machine.
6. In a grinding machine, the combination
with a driving center and a tail stock substan
tially in line with the driving center, of a live
center having a stationary stud engaged in the
tail stock and substantially in line with the driv
ing center, a head rotatably mounted on the stud,
and a center movably mounted on the rotatable
head and for transverse adjustment thereon.
7. In a machine for eccentrically grinding‘ pis
tons, a revoluble support for one end of a piston,
dead center and does not result in eccentric rota
tion of the work.
From the foregoing it is thought that the con
struction, operation and many advantages of the
herein described invention will be apparent to
those skilled in the art without further descrip
tion, and it will be understood that various
a second revoluble support forlthe other end of
ing means carried by the head for engaging work
supported by the center for driving the head from
the work.
3. In a live center assembly for machines, the
said assembly including a stationary stud and a
head rotatably mounted thereon, and having a
front face, the combination with a center mount
ed on the front face of the head and adjustable
transversely of the face, of spring means carried
by the face and located out of the line of adjust
extending transversely of its front face, a center
slidably mounted in the mortise, and screw
threaded means carried by the revoluble head
for adjusting the position of the center in the
the piston, and means carriedby the second rev
oluble support for holding the end of the piston h
in eccentric relation to the axis of rotation of
the said second revoluble support.
8. In a machine for eccentrically grinding pis
tons, including a head stock and a tail stock, the
changes in the size, shape, proportion and minor combination with a driving support for one end 30
of a piston, of a live tail-center comprising a sta
details of construction may be resorted to with
out departing from the spirit or sacri?cing any tionary stud mounted in the tail stock, a head
rotatably mounted on the stud and transversely
of the advantages of the invention.
adjustable means carried by the revoluble head
What I claim, is:
1. In a live center assembly for machines, a i for supporting the other end of the piston.
9. In a live center comprising a stud for sta
stationary stud for mounting in the tail stock of
a machine, a head rotatably mounted on the tionary mounting in a machine, a head revolubly
stud, and a center movably mounted on the front mounted upon the stud and having a front sur
face of the head for adjustment transversely of face, and a center movably mounted on the front
face of the head, and at one side of the center 40
the head.
2. In a live center assembly for machines, the line of the stud for eccentric rotation about the
said assembly including a stationary stud and a axis of the stud.
10. In a live center comprising a stud for sta
head rotatably mounted on the stud, a center
tionary mounting in a machine, a head revolubly
mounted on the front face of the head for move
mounted upon the stud, and having a mortise 45
ment transversely of the head, and work-engag
ment of the center, the said spring means ex
tending from the face of the head to a point
where they are engageable with work engaged
with the center.
4. In a live center assembly for machines, the
said assembly including a stationary stud and a
head rotatably mounted thereon and having a
front face, the combination with a center mount
ed on the front face of the head and adjustable
transversely of the face, of spring ?ngers secured
to the face at either side of the center, and ex
tending angularly outward. from the face of the
head and in a direction opposite to the direction
of rotation of the machine.
5. A live center assembly for machines com
prising a stationary stud, a head rotatably
mounted on the stud and having a dovetailed
mortise, the said screw threaded means being ac 50
cessible at the side of the head for operation
while the center is mounted in a machine.
11. The process of eccentrically grinding pis
tons that comprises supporting a piston between
centers, rotating one center and the end of the 55
piston supported thereby eccentrically, and dur
ing said rotation grinding off a portion of the
piston along a line parallel to the center of rota
tion of the piston.
12. The process‘of eccentrically grinding pis 60
tons that comprises rotating a piston eccentri
cally between centers, during such rotation grind
ing off a portion of one side of the piston along
a line parallel to its center of rotation, reversing
the eccentricity of rotation of the piston between 65
the centers by rotating the piston with respect
to the centers, and grinding off a second portion
of the piston on the opposite side to that first
ground along a line parallel to the center of rota
tion of the piston and during its rotation.
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