Note: Descriptions are shown in the official language in which they were submitted.
~3~5~59
I
CENTERLESS GRINDER CONST~ UCTION
1 ¦ This inven~ion relates to a centerless grinder of the
2 ¦ kind having a rotary grinding wheel and a rotary regulating
3 ~ wheel with a gap therebetween in which a workpiece may be
4 ¦ accommodated for grinding.
~ ¦ Centerless grinders are well known and conventionally
7 ¦ comprise a base on which a rotary grinding wheel is mounted for
8 ¦ rotation in one direction about a substantially horizontal axis
~ ¦ and a regulating wheel which confronts, but is spaced from, the
¦ grinding wheel and which is mounted on the base for rotation in
11 ¦ the same direction about an axis. The axis of rotation of the
12 ¦ regulating wheel frequently is inclined somewhat to the
¦ horizontal so as to enable a workpiece accommodated in the gap
14 ¦ between the grinding and regulating wheels to be fed
¦ automatically through such gap as the workpiece is ground.
1~ ¦ It i8 conventional to mount the grinding wheel, the
17 ¦ regulating wheel, or both, for adjustment toward and away from
18 ¦ one another and thereby vary the gap between such wheel~.
1~ Adjustability of the gap is necessary so a~ to enable the
¦ grinding machine to accommodate workpieces of different
21 ¦ diameters and also to compensate for wear of the grinding wheel
22 ¦ due to attrition and dressing. Although conventional centerless
¦ grinders include adjusting mechanisms for these purposes,
24 ¦ adjusting means should be provided to compensate for changes in
the peripheral speed of the grinding wheel because of the reduc-
¦ tion in its diameter due to such attrition and dressing. It is
~7 ¦ believed that some centerless grinders provide one, or possibly
a8 ¦ two, input driving speeds for the grinding wheel or regulating
a~ ¦ wheel, but in those instances in which the grinder is used to
~0 ¦ grind workpieces to extremely small tolerences, such limited
~3~ 359
1 sE ed adju~tments are inadequate.
2 Apparatus constructed in accordance with the invention
overcomes the prior art inadequacy by providing an infinitely
4 adjustable drive mechanism for the regulating wheel.
It is not uncommon for the coupling between the
~ regulating wheel and its driving means to comprise a complex,
7 geared transmission. Since the grinding wheel and the
8 regulating wheel are driven in the same direction, and since
8 the workpiece is positioned in the gap between the two wheels,
and since the grinding wheel conventionally is the larger wheel
11 and has a greater peripheral speed, the workpiece transmits a
12 force from the grinding wheel to the regulating wheel that
attempts to accelerate the latter. This phenomenon often i5
14 referred to as "back driving" and subjects the conventional
1~ geared transmission to severe strain and consequent wear. The
1~ adverse effect of the grinding wheel's tending to drive the
17 regulating wheel via the workpiece is particùlarly noticeable
18 in those instances in which workpieces are presen~ed to the
19 grinder in spaced intervals. Thus, when a ground workpiece is
removed from the gap between the wheels, the speed of the
21 regulating wheel may decrease, but when a fresh workpiece is
2Z introduced to the gap there is an immediate shock imposed on
the regulating wheel drive mechanism due to the grinding
~4 wheel's attempting to accelerate the regulating wheel. As a
consequence the speed of rotation of the regulating wheel
2~ varies, with adverse results on the finish of the workpiece,
a7 and the drive mechanism is subjected to wear.
a~ Apparatus constructed in accordance with the invention
2~ overcomes these disadvantages of the known grinders by
~0 utilizing a regulating wheel drive mechanism which positively
-- 2
~3~
1 resists any tendency to the regulating wheel.
2 The invertion as claimed provides a centerless
3 grinder construction comprising a base, a rotatable
4 grinding wheel mounted on the base Eor rotation about an
axis, and a body member mounted on the base for linear
6 movements toward and away from the grinding wheel. There
7 is a rotatable regulating wheel and carrier means mounting
8 the regulating wheel for rotation about an axis spaced from
9 the axis of the grinding wheel. Adjustable mounting means
mounts the carrier means on the body member for linear
11 movements with the body member and for rocking movements
12 relative to the body member about an axis normal to the
13 axis of rotation of the regulating wheel. Support means is
14 secured directly to the carrier means for movements
therewith. Driving means is rotatable about an axis spaced
16 from and parallel to the axis of rotation of the regulating
17 wheel. Drive transmission means is rotatable about an axis
18 spaced from and parallel to the axis of rotation of the
19 regulating wheel, the transmiæsion means including a
hydrostatic pump-motor assembly coupling the driving means
21 and the regulating wheel for rotating the latter. The
22 transmission means has an infinitely variable speed output
23 and is operable to maintain substantially constant any
24 selected output speed. Means secures the driving means and
the transmission means directly to the support means
26 whereby the driving means, the transmission means, and the
27 regulating wheel are conjointly and bodily movable relative
28 to the body member about the normal axis.
29 More particularly, a centerless grinder
A
~3~
1 constructed in accordance with the invention includes a
2 base on which is mounted a rotary grinding wheel and a body
3 member on which is mounted a rotary regulating wheel. The
4 body and, consequently, the regulating wheel are adjustable
toward and away from the grinding wheel so as to vary the
6 workpiece-accommodating gap therebetween. The regulating
7 wheel is carried by a carrier which is mounted on the body
8 for rocking movements about a substantially horizontal
9 axis, thereby enabling the axis of rotation of the
regulating wheel to be adjusted in a substantially vertical
11 plane.
12 The regulating wheel is coupled by drive
13 transmission means to rotary driving means. The regulating
14 wheel carrier and the driving means are rigidly secured to
one another for conjoint movement not only toward and away
16 from the grinding wheel, but also for conjoint rocking
17 movements. Securing the regulating wheel carrier and the
18 driving means to one another ensures that the drive
19 transmitting means which couples the driving means and the
regulating wheel will be maintained in a fixed position
21 relative to the driving means and to the regulating wheel,
22 thereby positively avoiding the imposition of undesirable
23 forces on the drive transmitting means due to rocking of
24 the axis of rotation oE the regulating wheel.
The regulating wheel driving means associated with
26 apparatus constructed in accoxdance with the invention is
27 infinitely variable in speed, thereby enabling optimum
28 relative peripheral speeds of the regulating wheel and the
29 grinding wheel to be maintained for the most efficient
grinding of a workpiece.
- 3a -
13~5~5g
1 The driving mechanism for the regulating wheel
2 incorporates self-actuating means which resi~t forces tending
to rotate the regulating wheel backwards and which also absorb
4 shocks caused by substituting a fresh workpiece for a finished
one.
7 A preferred embodiment of the invention is illustrated
8 in the accompanying drawings, wherein:
~ Figure 1 is a side elevational view of a centerless
grinding machine incorporating apparatus constructed in
11 accordance with the inventiont
12 Figure 2 is a fragmentary, greatly enlarged, sectional
13 view taken generally on the line 2-2 of Figure ls
14 Figure 3 is a sectional view taken generally on the
1~ line 3-3 of Figure 2, appearing with Figure l; and
1~ Figure 4 is a somewhat diagramatic view, on a reduced
17 scale, illustrating the opposite side of the apparatus shown in
18 Figure 3.
19
~20 A centerless grlnder 1 according to the invention has
21 a base 2 on which is mounted a housing 3 in which is journaled
2Z a rotary grinding wheel GW driven in the direction of the arrow
Z5 a by a suitable motor (not shown). The housing 3 is adjustable
~4 longitudinally of the base 1 by conventional adjusting means 4.
26 The machine 1 includes a body or housing 5 mounted on
2B the base 2 for adjustments longitudinally of the latter toward
~7 and away from the grinding wheel GW by means of conventional
a8 adjusting means 6. At that end of the housing 5 which
a~ confronts the grinding wheel GW is a carrier 7 in which is
~0 journaled a regulating wheel shaft 8 on which is fixed a
- 4 -
~3C~ i9
1 r gulating wheel RW. The car~ier 7 abuts a mounting plate 9
2 ¦ carried by the housing 5 and is provided with mounting bolts 10
at its opposite ends which extend through slots 11 formed in
4 the mounting plate 9. The bolts 10 may be loosened, when
desired, to enable the support 7 and consequently the regulating
~ wheel RW, to be rocked about a substantially horizontal axis
7 that is perpendicular to the axis of rotation of the grinding
8 wheel GW. The bolts 10 then may be tightened to maintain the
~ carrier 7 in any selected position of angular adjustment. The
carrier 7 also is adjuGtable vertically by means of a conven-
11 tional adju~ting mechanism 12 so as to position the axis of the
12 shaft 8 at a desired level.
Between the grinding wheel GW and the regulating wheel
14 RW is a support 14 on which a cylindrical workpiece WP may be
supported. The gap between the grinding wheel GW and the
1~ regulating wheel RW may be adjusted by either or both of the
17 respective adjusting means 4 and 6 to enable the workpiece WP
18 to be engaged by the peripheries of both of the whee~s.
19 The housing 5 has a bottom 16 provided with guideways
or the like ~not shown) to facilitate its adjustment longitudin-
21 ally of the base 2 i.e. toward and away from the grinding wheel
2Z GW. The housing 5 also has a rear wall 17, a front wall 18,
Z5 and side walls 19. The housing also has an upper wall 20
a4 provided with an opening 21. Accommodated in the opening 21 is
a support or mounting plate 22 of less area than that of the
opening 21. Fixed to and depending from the lower surface of
27 the plate 22 is a mounting plate 23 at the forward end of which
28 is fixed an extension 24 that is welded or otherwise suitably
fixed to a generally rectangular frame 25 having an opening 26
~0 thereinO The front wall 18 of the housing 5 has an opening 27
_5_ ~
1 t rein thlough which the exten~ion 24 and the mounting frame
2 25 freely extend. The mounting frame 25 is secured by bolts or
the like to the rear wall 28 of the carrier 7 r and such wall
4 has an ~pening 29 therein.
Means is provided for effecting rotation of the
~ regulating wheel RW and comprises an infinitely variable speed,
7 integrated, hydrostatic pump-motor coupling unit 30 of known
8 construction, such as that produced and sold by Dana Corporation
~ under the trademark HSV and described in its bulletin No.
MTP-003-85. In essence, the coupling unit 30 has a variable
11 displacement radial piston pump that drives a fixed displacement
12 radial piston mQtOr. The coupling unit is driven by a suitable
13 constant speed electric motor 31 having its output shaft
14 connected to the drive unit 30 in a conventional manner. The
drive motor 31 and the coupling unit 30 are mounted by supports
1~ 32 on the common support plate 22 and the unit 30 has its
17 output shaft fixed to a driving pulley or sprocket wheel 33
18 around which is trained a driving belt or chain 34 which also
19 is trained around a pulley or sprocket wheel 35 fixed on the
input shaft 36 of a geared speed reducer 37 of known kind. The
21 speed reducer 37 has a mounting flange 38 that is bolted or
22 otherwise fixed to the mounting plate 23, and such plate has an
opening 39 through which the output shaft 40 of the reducer 37
a4 extends. Fixed to the shaft 40 is a pulley or sprocket wheel
41 around which is trained a drive transmitting belt or chain
aB 42 which extends through the opening 2g in the rear wall 28 of
a7 the carrier 7 and is trained around a sprocket wheel or pulley
a8 43 that is fixed to the shaft 8 of the regulating wheel RW.
The construction and arrangement of the regulating
wheel driving mechanism and its support are such that the
l mo ting plate 22 is secured rigidly t~ the rear ~all 28 of the
2 regulating wheel carrier 7, but is not secured to the base 2 or
S the housing 5. Accordingly, the driving means, the regulating
4 wheel RW, and the drive coupling means are movable as a unit
and the axes of rotation of the coupling unit 30, the drive
~ motor 31, the reducer 37, and the regulating wheel shaft 8 are
7 maintained fixed at all times in parallel relationship. Thus,
8 whenever the regulating wheel housing carrier 7 is rocked to
~ tilt the axis of the shaft 8, the mounting plate 22 and the
drive components 30, 31, and 37, together with drive
ll transmitting chains or belts 34 and 42, also are rocked to the
12 same extent.
13 Since the drive motor, the drive coupling unit, and
14 the regulating wheel RW are fixed to the regulating wheel
1~ carrier 7, movement of the latter by the housing 5 longitudin-
l~ ally of the base 2 also will be imparted to the drive and drive
17 transmitting units. Such movements of the regulating wheel
18 carrier 7 and the regulating wheel are possible because of the
l9 securing of the carrier 7 to the mounting plate 9 of the
housing 5.
21 Conventionally, and as is shown in Figure 1, the
22 grinding wheel GW is of considerably larger diameter than the
23 rgulating wheel RW. The grinding wheel thus has greater mass
a4 and more inertia than the regulating wheel.
2~ In the operation of the apparatus, the grinding wheel
a~ GW is caused to rotate in the direction of the arrow a in a
a7 conventional manner by a suitable motor ~not shown3 and the
a~ regulating wheel RW is caused to rotate in the direction of the
2~ arrow b by means of the drive motor 31 and the coupling unit
~0 30. Either or both of the driving and regulating wheels is
- 7
~3;~8~
1 ad usted to provide a suf~icient gap tùerebetween as to accomm~-
2 date the workpiece WP for grinding. The regulating wheel also
is adjusted by the adjusting means 12 so that its axis of rota-
4 tion is at a level somewhat below the central axis of the work-
piece WP, as is conventional.
~ The regulating wheel support 7 is adjusted, by manipu-
7 ¦ lation of the bolts 10, so as to tilt the axis of rotation of
8 ¦ the regulating wheel an amount sufficient to effect feeding of
~ ¦ the workpiece in one direction or the other through the gap
¦ between the grinding and regulating wheels. The speed of
11 ¦ rotation of the regulating wheel 11 is set by manipulation of a
12 ¦ valve adjusting wheel 44 on the coupling unit 30 which
lS ¦ regulates the rate of rotation of its output shaft. A
14 ¦ workpiece WP then may be introduced to the gap between the
¦ grinding and regulating wheels for grinding.
1~ ¦ As the grinding operations progress, the grinding
17 wheel becomes worn due to attrition and dressing. The diameter
18 of the grinding wheel, therefore, gradually decreases. As a
19 consequence, the peripheral speed of the grinding wheel
decreases and the size of the gap between the grinding wheel
21 and the regulating wheel increases.
22 The size of the gap between the grindiny and regulat-
23 ing wheels may be maintained substantially constant by operation
a4 of the adjusting means 6 to effect movement of the body 5,
including the carrier 7, toward the grinding wheel. The speed
a~ of rotation of the workpiece may be maintained substantially
a7 constant by varying the speed of rotation of the regulating
a8 wheel RW by adjustment of the valve regulator 44 of the coupling
a~ unit 30. The adjustments of the position and speed of the
~ regulating wheel may be effected by automatic means, rather
~3~
1 t n manua1ly, if desired.
2 Whenever a workpiece is being ground the greater mass
and inertia of the grinding wheel GW causes the latter to exert
4 a force on the regulating wheel RW, via the workpiece, tending
to accelerate the speed of rotation of the regulating whee1.
In the disclosed construction these tendencies are positively
7 overcome by the hydrostatic pump-motor coupling unit 30. This
8 is possible because, when a retarding force is imposed on the
~ motor of the pump-motor assembly, the motor converts itself
into a pump which opposes the pump of the pump~motor assembly.
ll As a consequence, retardation of the speed of rotation of the
12 regulating wheel is virtually non-existent and shocks caused by
13 replacement of ground workpieces with fresh workpieces are
14 absorbed by the pump-motor assembly.
1~ The disclosed embodiment is representative of a
lB presently preferred form of the invention, but is intended to
17 be illustrative rather than definitive thereof. The invention
19 i~ fined in the claims.
223
26
~8
