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The invention relates to a device for lapping balls and, more particularly,
to a device for lapping balls in continuous operation.
Apparatus or devices for the afore-referred to general purpose are used for
grinding or polishing and lapping of spherical surfaces, that is, for soft
working of balls after pressing, and also for filing, flashing, soft
grinding or polishing and also for working after hardening, that is to
say, for hard grinding or polishing and lapping.
In the case of a particular type of ball working apparatuses the ball is
held at three points and these abutment surfaces are made annular and at
least one is driven so that the balls are caused to rotate. At another
position of the ball a grinding or polishing wheel comes into engagement
for working the ball surface. This category of apparatus also includes
constructions in the case of which both or all three discs holding the
balls are caused to rotate in order to provide for a more intense
treatment of the surface. This working operation is, however, at the most
only suitable for pre-grinding or polishing balls, that is to say, a
working operation which does not raise any high requirements as regards
the evenness and complete roundness of the work pieces.
In order to achieve an improved working of the ball surface no additional
grinding or polishing wheel was then used and the balls were arranged
between three rotating cast discs, of which two annular discs, arranged
concentrically in relation to each other, rotated in opposite directions
so that the balls continuously turned about their axes. The third disc
rotated coaxially in relation to the two others and thus brought about a
rotation of the balls about a further axis, which lay at an angle of
approximately 90.degree. to the other axis of turning. The balls ran in
grooves adapted to suit their shape. In accordance with whether use was
made of at least one grinding or polishing disc or of lapping discs this
method of procedure could be used for pre-grinding or polishing and also
for lapping. Owing to particular features of the apparatus, however, the
method was not adopted commercially. At the most, it was only suitable for
working a certain series of balls dependent on the size of the discs. For
changing the charge it was necessary to stop the machine and lift one disc
in order to remove the balls and to place a new charge or batch in the
apparatus.
Another apparatus used two discs operated less intensively but more
rationally. This apparatus comprised two discs of which one rotated and
the other was stationary. A sector-shaped opening was provided for a
constant exchange or renewal of the balls. Owing to the fact that in the
case of this apparatus several series of balls could be processed jointly
on one pair of discs any number of balls could be subjected simultaneously
to the grinding or lapping process without having to pay attention to the
size of the balls. It is of great importance that the movement of the
balls should be controlled so that the balls run along tracks of different
diameter between the two discs with a constant changeover.
The requirements as regards surface quality and accuracy of the balls
become more and more stringent with the requirements as regards
rationalization of production. Particular importance must be paid to the
requirement of being able to adapt the working of the balls as far as
possible to the respective requirements in hand.
Summary of Invention
One object of the invention is to provide a novel and improved device for
lapping balls with a high degree of precision and also for soft working of
balls after processing, such as filing, flashing, soft grinding or
polishing, etc.
A further object of the invention is to provide a novel and improved device
which is suitable for hard grinding or polishing in such a manner that the
balls can be processed by a single passage through the grooved track
between working surfaces so as to be practically completely finished.
A device for working the surface of balls in a grooved track formed between
two working surfaces is characterized in accordance with the invention in
that the balls are worked between a stationary working surface on the one
side and two working surfaces, moved in opposite directions, on the other
side with one passage along the grooved track. This manner of procedure
fulfills all conditions for continuous operation, since the use of a
stationary disc makes possible the arrangement of a ball inlet and a ball
outlet. The method furthermore makes it possible to control the timing of
working of the ball surfaces within very large limits, that is to say one
passage of the balls along the grooved track can serve both for a short or
less intensive working and also a particularly intensive surface treatment
of longer duration. This is based on the following principle:
Due to the opposite movement of the two working surfaces, which lie
opposite to the stationary working surface, the balls are firstly caused
to perform a type of spinning movement in the case of the use of annular
disc-shaped or disc-shaped working surfaces, and they turn on the
stationary working surface. It is only when there is an equal peripheral
speed of these two working surfaces that the ball remains at its
respective position in the groove track. Even in the case of small angular
velocities of two annular discs rotating concentrically around each other
the individual ball has a further component of movement imparted to it
owing to a rotation about a further axis in the course of the grooved
track, that is to say in the direction of movement of the annular disc
with the larger radius. It is, however, now possible to arrange for the
movement of at least one of the annular discs to be variable in order by a
suitable difference in the speeds of movements of the two working
surfaces, make possible a more or less rapid passage of the balls along
the grooved track. If this difference is large, the balls will rapidly run
along the whole grooved track and if it is small, the balls will only move
slowly forwards, something which corresponds to intense working, in
contrast to a more superficial working of short duration in the other
case. By suitable setting of the conditions of movement of the two working
surfaces on the one side of the balls the advance of the whole of the
balls located between the three working surfaces can be regulated as
desired.
The abutment surfaces of all three working surfaces envelop the balls
substantially and guarantee a very effective working moment, which
accelerates the grinding or polishing or lapping process in a surprising
manner.
The working surfaces can be circular or annular discs. It is also possible
for at least the stationary working surface arranged opposite to the
rotating annular discs to form a circular arc of less than 360.degree..
The method in accordance with the application can also be carried out with
working surfaces curved in accordance with an arc and which swing
backwards and forwards through an angle of less than 360.degree. in
relation to the stationary working surface. The grooved track can lie
axially between the stationary working surface and two moving working
surfaces. It is, however, also possible to arrange the three working
surfaces in a single plane around each other so that the grooved track is
located in the radial intermediate space between the three working
surfaces.
The invention also discloses an apparatus or device with a ball inlet and a
ball outlet. This apparatus is characterized by the combination of a
stationary working surface on the one side and two working surfaces which
can be moved with an opposite direction of rotation on the other side of
the grooved track. The working surfaces include in this case as well as
the whole zone between a closed circle, for example in the form of an
annular disc, and a straight line, for example a stationary rail or a rail
moving backwards and forwards linearly.
If the disc-shaped working surfaces have a sinusoidal grooved track, the
manner of operation can be still further improved since in this case the
engagement angle of the balls on the individual discs constantly changes.
A correspondingly advantageous fact can also be achieved if the grooved
track is sinusoidally shaped on one side, that is to say on the stationary
working surface or on the two moving working surfaces.
In accordance with a further feature of the invention it is possible to
arrange a cage protecting the balls in the grooved track in order in this
manner to protect the individual balls from mutual contact and concomitant
damage.
A further feature of the invention provides for the stationary working
surface being arranged below the two moving working surfaces and having
the ball inlet and the ball outlet. At the ball outlet and/or the ball
inlet it is possible to provide a guide tract, which may be curved, for a
movement of the balls in accordance with gravity. In the case of a
stationary working surface arranged underneath the balls to be worked roll
under their own weight along the guide path or track and enter the grooved
track. This operation is not hindered by a cage in the working gap between
the working surfaces. For the inlet and outlet for the balls it is
sufficient to provide a simple interruption in the stationary working
surfaces.
A still other and important feature of the invention is to provide a novel
and improved device in which the movable working surfaces are each driven
by a driving means such as an electric motor and that the speeds with
which the working surfaces are driven can be independently regulated. This
has the advantage that the time required by the balls to pass through the
grooved track can be varied in accordance with the specific machining
required by the balls whereby the drive can be rapidly and accurately set
for a maximal output.
LIST OF SEVERAL VIEWS OF DRAWINGS
Further features, details and advantages of the invention will be gathered
from the following description of a few embodiments.
FIG. 1 is a diagrammatic cross-sectional view of a device in accordance
with the invention, the section being taken at the grooved track between
the working surfaces;
FIGS. 2 and 3 show corresponding sections of a modified embodiment of the
invention;
FIG. 4 is a plan view of an annular stationary working surface of the
embodiment in accordance with FIGS. 2 and 3;
FIG. 5 is a simplified sectional view of a ball outlet;
FIG. 6 is a simplified sectional view of a ball inlet;
FIG. 7 shows a diagrammatic lengthwise sectional view of an embodiment of a
device in accordance with the invention;
FIG. 8 is a modification of the speed regulating means for the drive means;
FIG. 8A is a view of FIG. 8 taken on line 8A-8A of FIG. 8;
FIG. 8B is a fragmentary lengthwise section of FIG. 8 on an enlarged scale;
FIG. 9 is another modification of the regulating means;
FIG. 10 is still another modification of the regulating means; and
FIG. 10A is a fragmentary lengthwise section of FIG. 10 on an enlarged
scale.
DESCRIPTION OF PREFERRED EMBODIMENTS
The ball 1 whose surface is to be worked is located in the working gap 2
between a stationary working surface 3, lying underneath the ball 1 in the
case of the particular embodiment of the invention under consideration,
and the two working surfaces 4 and 5 arranged on the other side of the
ball, that is to say opposite. They substantially entirely envelop the
ball 1 and the engagement line a of the stationary working surface 3 has a
central engagement point a.sub.1. The engagement line b in the working
surface 4 corresponds to the central engagement point b.sub.1 and the
engagement line c of the other moving working surfaces 5 corresponds to
the central engagement point c.sub.1. Possibly the ball 1 may be accepted
in a cage 6 arranged in the working gap 2 between the working surfaces 3,
4 and 5 and this cage protects the ball against damage by knocking
adjacent balls 1.
The two working surfaces 4 and 5 move, as can be seen from FIG. 1, with an
opposite direction of movement leading out of the plane of the drawing. If
these working surfaces 4 and 5 are constructed linearly, it is a question
of a reciprocating movement which is also linear. If the working surfaces
4 and 5 are circular, the reciprocating movement can be in the form of
oppositely directed reversing swinging movements. If it is a question of
annular or circular working surfaces 4 and 5, a mutually opposite rotary
movement of the working surfaces 4 and 5 takes place.
Due to the oppositely directed movement of the working surfaces 4 and 5 the
ball 1 is firstly caused to carry out a rotary movement about its own axis
x--x. In the case of an equal peripheral speed of disc-shaped working
surfaces 4 and 5 the ball 1 would remain stationary in relation to the
stationary working surface 3 and rotates only about its axis x--x. If,
however, these peripheral speeds are different, a further working of the
ball surface along the engagement lines b and c of the working surfaces 4
and 5 takes place and the ball 1 additionally rotates about an axis y--y
and is caused to carry out an advancing movement along the grooved track 7
in the lower stationary working surface 3. The direction of this advancing
movement corresponds to the direction of movement of the working surface 4
or 5, respectively, which moves in relation to the other surface with the
higher peripheral speed. It depends upon the difference in movement of the
working surfaces 4 and 5 whether the balls 1 lying in the grooved track 7
pass more slowly or more rapidly along the whole length of the grooved
track. This means that there is a more intense or a less intense working
of the surface of the ball 1.
FIGS. 2, 3 and 4 show an embodiment of the invention in the case of which
the grooved track 7 is sinusoidal and the pitch L of the sinusoidal arc is
approximately the same as the periphery of the balls (D) to be worked.
FIG. 2 shows an arrangement in which the engagement lines a, b and c are
displaced radially outwards and FIG. 3 shows an arrangement in which they
are disposed radially inwards, that is to say in the reverse direction.
FIG. 4 shows a plan view of the sinusoidal grooved track 7 of a
disc-shaped stationary working surface 3.
FIG. 7 shows one of a number of possible embodiments of the apparatus in
accordance with the invention in which the working members 3, 4 and 5 in
the form of rings or annular discs rotate about a vertical axis 8. On the
cross-piece 9 of the frame 10 there rests the stationary working surface
3. In the two bearings 11 and 13 a shaft 13 is journalled, on which a
drive wheel 14, for example a pulley or the like is fixed, which is
connected via the drive element, such as a bell, 15 with the driving
pulley 16 of an electric motor 17 mounted on the frame 10. The direction
of rotation of this drive is indicated by the arrow 18. On the shaft 13 a
disc-shaped support 19 for the working member 5, opposite to the
stationary working member 3, is keyed. The working member 5 is in the form
of an annular disc in this particular embodiment of the invention.
In the case of this embodiment of the invention there is also an annular
disc-shaped working member 4 arranged concentrically around the working
disc 5. The disc 4 is arranged on the support 21 fixed to the shaft 20. On
this shaft 20 the drive wheel 22, for example a pulley or the like, is
keyed. The pulley is connected via the drive element 23 such as a belt and
the driving wheel 24 with an electric motor 25 attached to the frame 10.
This drive rotates in the direction of the arrow 26 so that the working
discs 4 and 5 rotate in opposite directions. The shaft 20 is journalled in
the two bearings 27 and 28 of the frame 10.
As shown in broken lines in FIG. 1 the grooved track 7 in the stationary
working disc 3 can be divided up by a groove 29 produced by turning.
As it is shown in FIG. 5, on working disc 3 which is stationary a recess 30
is provided as a guide track or path for the balls leaving the ball outlet
31. If a ball 1 on moving between the working discs 2 and 4 and 5 comes to
the ball outlet 31, it falls automatically downwards and thus ceases to be
subjected to the working process.
In the direction of movement of the balls 1 along the grooved track 7 a
ball inlet 32 follows the ball outlet 31. This ball inlet 32 is shown in
FIG. 6 by way of example and has a guide track 33, which leads with a
slight curvature from a higher level to the ball inlet 32 so that the
weight of the balls 1 located in the guide 33 causes the balls to pass
into the grooved track 7.
As it is evident, the speed differential between working discs 4 and 5
controls the speed of movement of the balls through the gaps and thus the
dwell time of the balls in the gap. The invention provides that the
relative speed of the rotary discs can be independently regulated, thereby
correspondingly varying the dwell time. This has the advantage that the
dwell time can be set in accordance with the extent of lapping required by
balls to be machined in the device. As a result, the device can be
conveniently and rapidly set for pushing of balls in one passage and thus
for maximal output and, most economic use.
Various means, conventional and non-conventional, can be provided, and are
available, for regulating the relative speeds of working discs 4 and 5. It
is, for instance, possible and practical to change the diameter of pulleys
14 and 22 so that the desired speed differential is obtained. The ratios
of transmission means between drive motors 17,25 and the respective
pulleys can be gradually or stepwise varied but generally it is more
convenient to vary the rotational speed at the motors themselves. There is
indicated in FIG. 7 for each of the drive motors a block 40 and 41,
respectively, including the legend "speed regulator." These blocks are
indicated to be connected to the respective motor and should be visualized
as including conventional and suitable speed regulators as are readily
available in the market. Of course, it may be sufficient to change the
speed of one motor only.
Provision of speed regulators for each of the motors permits varying the
rotational speeds of the two motors independently of each other and thus,
also, the rotational speeds of working discs 4 and 5. Regulation of the
r.p.m. of either of the two motors can be effected either automatically or
by manual control as it is wellknown in the art.
FIGS. 8, 8A and 8B show further speed adjustment means for varying the
speed with which pulley 26 is driven by belt 23. There is shown a pulley
42 of the type having conical side walls 43 and a cylindrical center
portion 44. Belt 23 is shown as riding on the center portion 44 of the
pulley, that is, belt 23 shown as a V-shaped belt, is driven at the
minimum speed provided by the r.p.m. of the motor on constant. Speed
transmitted to pulley 26 can be increased by tilting pulley 42 so that the
belt is riding on one of the conical inner side walls of the pulley,
thereby increasing the effective diameter of pulley 42.
Referring to FIG. 8B, pulley 42 consists of two halves 42a and 42b. Pulley
half 42b is fixedly secured to motor shaft 65 for driving by this shaft.
The other pulley half is keyed to the shaft by a key 66 so that it is also
driven by shaft 65 but is axially slidable relative to pulley half 42b
thereby varying the spacing between the two pulley halves. A spring 67
between the two pulley halves biases pulley half 42a in the direction away
from pulley half 42b. This upward movement of pulley half 42a is limited
by a disc or protrusion 68 fixedly secured to shaft 65. A second spring 69
biases pulley half 42a towards the other pulley half, i.e., the two
springs act in opposition. The gap between the two pulley halves is
bridged by an annular flange 70. As it is evident, tilting of pulley 42
will cause a change in the spacing of the two pulley halves and thus a
corresponding change in the position of belt 23 relative to the conical
inner wall surfaces of the pulley, thereby correspondingly changing the
speed which is transmitted by belt 23 to pulley 26.
Tilting of pulley 42 is effected by mounting motor 25 on a frame structure
50 which is pivotal together with motor 25 about a pivot pin 51. This
pivoting can be effected by a lever 52 in one direction or the other out
of the position in which it is shown in FIG. 8. Such pivoting can be
manually effected, or by speed adjustablr auxiliary motor 55 as it is
shown in FIG. 8A. Of course, conventional hydraulic or servo means can
also be used for the purpose. The same or similar arrangement may also be
provided for motor 17 to vary the r.p.m. of pulley 14.
FIG. 9 shows an arrangement in which the r.p.m. of rotary disc 14 can be
adjusted by interposing a variable gear drive 56 between motor 17 and
pulley 16. Variable gear drives are widely known and readily available in
the market. The transmission ratio of the gear drive can be readily
stepwise or gradually adjusted, either manually or automatically. A knob
or wheel 57 for adjusting the ratio of the gear drive is indicated. The
arrangement which is shown in FIG. 9 for motor 17 can, or course, also be
used for motor 25.
According to FIGS. 10 and 10A, the rotational speed of either working disc
can be adjusted by providing at shaft 13 and on the drive shaft 65 of
motor 17 pulleys 60 and 61 of the conical type. The belt 62, such as a
V-belt, is shown at the center part of the pulleys, that is, transmission
of speed is at the minimal ratio. A manually or automatically operable
wheel 63 is provided for setting pulley 61 so that the belt 62 is forced
into positions in which the ratio of transmission is either increased or
decreased as selected.
Referring to FIG. 10A, pulley 61 is similar to pulley 42 in that the pulley
consists of two halves 61a and 61b. Pulley half 61b is fixedly secured to
motor shaft 65 while pulley 61a is keyed to the shaft by a key 75 so that
the pulley half can be axially displaced relative to pulley half 61b but
is also driven by shaft 65. A spring 76 biases pulley half 61a in the
direction away from the other pulley half. An annular flange 76 bridges
the gap between the two pulley halves.
Wheel 63 has on its bottom side a cam surface 77 which coacts with a cam
surface 78 on the top side of pulley half 61a. The pulley assembly and
also the hand wheel are retained on motor shaft 65 by a lock washer 80 or
other suitable element. As it is apparent, turning of the hand wheel will
vary the position of pulley half 61a relative to pulley half 61b against
the action of spring 76, thereby correspondingly varying the position of
V-shaped belt 62 relative to the conical walls of the pulley and thus
correspondingly changing the rotational speed transmitted to pulley 60.
Of course, the afore-referred to manual control means can be replaced in
the disclosed control assemblies by electrical, hydraulic or otherwise
operated control means. The V-shaped transmission belts can be replaced by
chain belts.
While the invention has been described in detail with respect to certain
now preferred examples and embodiments of the invention, it will be
understood by those skilled in the art, after understanding the invention,
that various changes and modifications may be made without departing from
the spirit and scope of the invention, and it is intended, therefore, to
cover all such changes and modifications in the appended claims.
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