FIELD OF APPLICATION
The present invention relates to an automatic pairing and ball filling machine for
. facilitating assembly of deep groove ball bearings at a very high speed of for
example, 5 second / bearing cycle time.
The components of a deep groove ball bearing are inner race, outer race, rolling
element and the retainer. The internal clearance between the inner and outer
clearance should be within a tolerance of ± 1 micron. Right size and right
number of balls are to be inserted between the raceways.
BACKGROUND OF THE INVENTION
Ball bearings are at the heart of almost every product with a rotating shaft. We
have come to rely heavily on these products and in turn on the bearings too for
the benefits they provide. We expect these products (and the bearings within)
to give us uninterrupted, dependable "lifetime" service. Highly precise surface
finish, material properties, cleanliness, dimensions and tolerances of bearings
contribute significantly to product performance. As a part of tolerances, the
predictable repeatability in the manufacturing and assembly process is crucial to
ensure consistent bearing performance. Hence, the performance of the bearings
heavily depends on the manufacturing and assembly process of bearings
components.

SUMMARY OF THE INVENTION
Accordingly, there is provided an automatic pairing and ball filling machine for
high-speed assembly of deep groove ball bearings, comprising rotary hoppers
and vertical elevators , for continuously feeding inner and outer races to at least
one measuring station for measurement of said inner and outer races, the at
least measuring unit measuring internal clearance of the inner and outer races
to determine from a set of-pluraIity-sized balls the applicable ball size for the
inner and outer races; at least one meeting unit for selecting and pairing the
races based on selected ball size, the rejected races being transferred to a split
unit; a ball hopper and divider unit for dispensing right number and size of balls
to a ball insertion unit for inserting the balls into the paired races.
The main object of the present invention therefore, is to provide an automatic
pairing and ball-filling machine for sizing, matching and ball filling to facilitate
assembly of deep groove ball bearings at a high speed.

In order to achieve this and other objects in the present invention the process
includes feeding of inner and outer races, measuring the raceways, ball
matching, race meeting and ball insertion. Rotary hoppers and vertical elevator
units are provided for continuously feeding inner and outer races of the bearings
to the measuring stations for measuring the inner and outer races. In the
measuring stations a measuring unit comprising linear voltage differential
transformer (L VDT) pencil probes are provided for measuring the inner and
outer races separately. Meeting unit and spit units can be provided for meeting
of outer and inner races on one center and change the orientation of the paired
races at 90°.

The ball insertion unit comprises a pusher unit, vice unit, a bar and a ball setter
unit for positioning the races below the ball setter for ball insertion.
A ball hopper and divider unit comprises ball container, ball divider and ball
collector units for dispensing the right number and size of balls to the ball
insertion unit.
A micro processor controller and an operator panel command pneumatic
actuators and sensors for carrying out the entire sequence of operation
described above. A suitable programmable logic controller (PLC) is provided for
running the machine operation and control logic. The PLC also decides on the
appropriate ball size based on the measurement of the internal clearance
between the inner race and the outer race. For running the rotary hopper a
separate control panel is provided with necessary interface.

Thus the present invention provides an automatic pairing and ball filling machine
for facilitating the assembly of deep groove ball bearings at high speed,
comprising: rotary hoppers and vertical elevation units for continuously feeding
inner and outer races to measuring stations for measurement of said inner and
outer races; meeting units for pairing the races; and a ball hopper and divider
unit for dispensing right number and size of balls to a ball insertion unit for
inserting the balls into the paired races.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention will now be described with reference to the accompanying
drawings where
Figure 1 shows in schematic arrangement the automatic pairing and
ball filling machine of the invention.
Figure 2 shows the calculation of internal clearance C between the
inner and outer race.

Figure 3 shows the flow chart for rotary hopper (inner race).
Figure 4 shows the flow chart for rotary hopper (outer race).
Figure 5A
and 5B show flow charts for measuring unit (inner race).
Figure 6 shows flow chart for measuring unit (outer race).
Figure 7 shows flow chart for meeting unit.
Figure 8 shows flow chart for ball filling unit.
Figure 9 shows flow chart for ball hopper and divider unit.
DETAILED DESCRIPTION
As shown in Figure 1, the automatic pairing and ball filling machine of the
present invention is provided with two rotary hoppers 1, 2 and two vertical
elevation units 3, 4 which are used for continuously feeding the inner and outer
races to measuring stations 7, 8 through slant chutes.

Escape units 5, 6 control the free flow motion of the races and these races are
stopped at the measuring stations 7,8 by stopper units 9,10.
The hoppers, the vertical elevators, the measuring stations, the escape units and
the stopper units are provided one for each race inner / outer.
On measuring stations 7, 8 the inner and outer raceways are separately
measured for their internal clearance by using linear voltage differential
transformer (L VDT) pencil probes.
Based on these measured internal clearance C (Figure 2) of the raceways
appropriate ball size is decided from set of predefined sizes of the balls.
After ball matching, these races are paired in meeting units 13. The unmatched
races are rejected at a no-good (NG) unit 11,12.
These paired races are collected in a mandrel of spit unit 14.

The orientation of these paired races are changed and these are placed at a
pusher table where a pusher unit 15 feeds the paired races to the insertion
station.
A ball hopper and divider unit 18 is provided which comprises eleven numbers of
containers each filled with balls of predefined sizes. Balls sizes vary from -10
micron to +10 micron with a difference of two - micron ball pitch for each
hopper. The ball hopper unit 18 is used to divide and release the right number
of balls with right size based on the raceways measurement.
A ball insertion on unit 17 is provided which consists of a bar, a ball setter and a
locater.
A vice unit 16 positions the paired races below the ball setter and deforms the
outer race within the elastic limit to create an oval shape for proper ball
insertion. The bar clamps the inner race in position to prevent it from moving
during ball insertion process. A stopper unit 19 provided allows and stops the
machined balls to be inserted. The ball setter inserts the balls properly and
without being overlapped in the paired races.

The locater centers the inner race which ensures proper distribution of the balls
in the bearing.
The entire sequence of operation is done by set of pneumatic actuators and
sensors. A microprocessor controller and operator panel command these
actuators. The machine operation and control logic runs in a suitable PLC. This
PLC is interfaced to all the four units of the machine to fulfill the interlocking and
sequencing requirement of the four units. Additionally this PLC decides
appropriate ball size based on the measurement of internal clearance C (refer
Fig: 2) done by the measuring instrument. There is a separate control panel
provided for running rotary hopper with necessary interface.
An operator panel 20 is located in front of the machine with appropriate controls
and indicates operation of the machine. Operator can select various machine
preset parameters and run the machine in Auto using controls of this panel. Also
suitable diagnostic features and visual indicators have been provided for
parameter tracking and locating operational faults. Manual controls have been
provided to operate the components and set the machine during sequence
failures. The operator gets fault condition indications and group indications as
well as audio alarm in case of any sequence fault. A signal tower with green,
yellow and red lamps are used to indicate working, ready and fault status of the
machine.

Various binary sensors like magnetic reed switches, inductive proximity switches
and infrared through beam and retro reflective type of sensors is used to track
the material flow and detect position of the actuators. All the actuators used
with the machine are pneumatic actuators. The machine uses 70 sensors and 50
pneumatic actuators, two motors. One vibrator unit is attached to outer race
measurement system to ensure proper grip of the measurement tooling in the
outer race before measurement starts.
The entire sequence of operation of the machine is controlled by ladder logic and
PLC. Ladder logic - a programming technique using a ladder-like structure. It
was originally adopted because of its similarity to relay logic diagrams to ease its
acceptance in manufacturing facilities.
The PLC continuously scans the inputs and changes the outputs into memory.
After this, the ladder logic program is run once and it creates a temporary table
of all outputs in memory. This table is then written to the outputs after the
ladder logic program is done. This continues indefinitely while the PLC is
running.

In this also included the safety interlocks, fault diagnostic and visual indications
to run the machine at low maintenance cost. The details of logic control are fully
illustrated in the flow charts of Figures 3-9 which are self explanatory.
Thus the automatic process of assembling deep groove ball bearings of the
present invention is capable of assembling bearing components at a very high
speed with a cycle time of 5 second / bearing and within ± 1 micron
repeatability.

We Claim:
1. An automatic pairing and ball filling machine for high-speed assembly of
deep groove ball bearings, comprising:
-rotary hoppers (1,2) and vertical elevators (3,4) , for continuously feeding
inner and outer races to at least one measuring station (7,8) for
measurement of said inner and outer races, the at least measuring unit (7,8)
measuring internal clearance ( c) of the inner and outer races to determine
from a set of-plurality-sized balls the applicable ball size for the inner and
outer races;
- at least one meeting unit (13) for selecting and pairing the races based on
selected ball size, the rejected races being transferred to a split unit (14);
- a ball hopper and divider unit (18) for dispensing right number and size of
balls to a ball insertion unit (17) for inserting the balls into the paired races.

2. The automatic pairing and ball filling machine as claimed in claim 1,
wherein slant chutes are provided for continuously feeding the inner and
outer races to said rotary hoppers (1,2) using said vertical elevators (3,4).
3. The automatic pairing and ball filling machine as claimed in claim 1,
wherein stopper units (19) are provided for stopping the balls from
inserting into said insertion unit (17).

4. The automatic pairing and ball filling machine as claimed in claim 3,
wherein the measuring unit (7,8) is configured to separately measure the
inner and outer races for their internal clearance using a linear voltage
differential transformer (LVDT) probe.
5. The automatic pairing and ball filling machine as claimed in claim 4,
comprising a vice unit (16) to deform the selected outer races to an oval
shape for allowing insertion of the balls.
6. The automatic pairing and ball filling machine as claimed in claim 5,
wherein the ball hopper and divider unit (18) comprises a plurality of balls
of different sizes, and wherein the ball sizes vary from -10 micron to +10
micron.
7. The automatic pairing and ball filling machine as claimed in claim 1,
wherein a microprocessor based operator panel (20) is arranged in front
of said machine for its operation with the help of a set of pneumatic
actuators and sensors.

8. The automatic pairing and ball filling machine as claimed in claim 7,
wherein a programmable logic controller (PLC) is provided for a controlled
and synchronized machine operation.
9. An automatic pairing and ball filling machine for high-speed assembly of
deep groove ball bearings, as substantially described and illustrated herein
with reference to the accompanying drawings

ABSTRACT

TITLE: " AN AUTOMATIC PAIRING AND BALL FILLING MACHINE FOR HIGH-
SPEED ASSEMBLY OF DEEP GROOVE BALL BEARINGS"
The invention relates to an automatic pairing and ball filling machine for high-
speed assembly of deep groove ball bearings, comprising rotary hoppers (1,2)
and vertical elevators (3,4), for continuously feeding inner and outer races to at
least one measuring station (7,8) for measurement of said inner and outer races,
the at least measuring unit (7,8) measuring internal clearance ( c) of the inner
and outer races to determine from a set of-plurality-sized balls the applicable ball
size for the inner and outer races; at least one meeting unit (13) for selecting
and pairing the races based on selected ball size, the rejected races being
transferred to a split unit (14); a ball hopper and divider unit (18) for dispensing
right number and size of balls to a ball insertion unit (17) for inserting the balls
into the paired races.