FIELD OF THE INVENTION
The invention generally relates to an auto-mechanism of tool
movement. More particularly the invention relates to auto-control
device to retract cutting tool of CMC-lathe during power failure while
in operation,
BACKGROUND OF THE INVENTION
In typical machine shop, the application of lathe machine plays a vital
role. In modern days, the applicability of improved CNC lathe
occupied a lion-share in metal cutting operations in modern machine
shop. One of such metal cutting operation is known as groove cutting
operation generally performed on the hoist-drum of E.O.T. cranes.
During groove cutting in hoist drum of E.O.T cranes, the chuck
rotates and feed at X and Z axis are both being applied in operation.
Whenever power failure occurs while the machine in operation, the
chuck holding with the job (drum) generally takes some time to stop
at rest due to high inertia of circular rotation and the cutting tool is
still remain in contact with the job. During this power cut-off period
the tool fitted with tool post damages the rope drum groove.
It requires an additional time as well as labour to rectify the damaged
groove by welding and re-machining. This leads to avoidable cost
and time.
OBJECT OF THE INVENTION
It is therefore an object of the invention to propose an improve auto-
control device to retract tool in CNC lathe machine during power
failure which eliminate the difficulties in prior art.
Another object of the present invention is to propose an improve
auto-control device to retract tools in the CNC lathe machine during
power failure which protects the job from damages arising out of
inertia of job rotation and concurrent tool movement.
An yet another object of the present invention is to propose an
improve auto-control device to retract tool in the CNC lathe machine
during power failure which eliminates the unnecessary repairing of
jobs arising out of undercut of metals from job.
A further object of the present invention is to propose an improve
auto-control device to retract tool in the CNC lathe machine during
power failure which affords to increase the productivity of machine.
A still further object of the present invention is to propose an improve
auto-control device to retract tool in the CNC lathe machine during
power failure which saves cost and time of operation.
SUMMARY OF THE INVENTION
A method by adapting 2 numbers heavy duty batteries, one micro
PLC, 2 numbers small relay having coil voltage + 24 V DC and 3
numbers 32 Amps contactor of coil voltage 220V . AC and made
connections to all the devices as per the cut diagram. A simple PLC
logic to micro PLC written to operate the 32A power connector as per
the requirement, so that the machine tool post i.e. X-axis, servo
motor comes back out of the groove which was in operation during
power cut at the machine so that the job can not be damaged.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 electrical diagram in lathe machine as per invention.
Figure-2 logic diagram of PLC of Figure 1
Figure 3 real time clock parameter to change the battery.
BRIEF DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fig. 1 and 2, in the circuit configuration, power suppiy of
the micro PLC at terminal L and N is connected to a UPS supply 220
VAC and the same supply is fed to a common point of the Q1, Q2,
and Q4 output to operate a plurality of contactor K1, K2 and K3
respectively . The micro PLC is connected to a plurality of inputs (I1,
I2, I3, I4, I5 &I6). The Input (I1) from a relay which acknowledges the
availability of machine's power supply.
In other words, when power source available in the machine, the
relay gets ON and from its no contact the input (I1) is available at
input terminal (I1) of the PLC. The input (15) is the emergency input,
ie. in case of the machines, electrical power failure, a first emergency
relay gets ON when the machine is in normal condition. Whenever an
emergency push button is activated, the first emergency relay will
get OFF. A second emergency relay in parallel with the first
emergency relay is provided to take the Input (I5) at the PLC input
Terminal (I5).
The Input (I3 and I2) are the N>C, contacts of the contactors K2 and
K1 to provide an interlock so that both the contact (K1, K2) can not be
energized at a time.
The input (I6) is provided by a toggle switch to operate the X-axis of
the machine, during power cut as per operator's requirement. If the
input (I6) is not high the X-axis moves away from the job to disable
performance during the power cut.
As soon as the operator causes the main switch ON, K1 contactor
gets ON and the X axis motor gets connected to the X axis drive (A)
at Terminal 5,6,7,8 as shown in the figure. Operator starts the
machine by activating the job related program. As soon as the power
fails the inputs (I1, I5) get low state and the output (Q1) gets low and
the contactor (K1) gets OFF immediately the output Q2 of the PLC
gets high to get ON the contactor K2 energised immediately for a
movement as specified by timer provided in the PLC logic and the
contactor gets OFF. During its ON condition, the X-axis servo motor
connected to the batteries runs for a brief moment and the tool head
comes away from the cutting surface of the job and the motor stops.
A + 24V SMPS power supply is provided for the battery charging
purpose. In the micro PLC by using a real time clock, the defined
time has been set to get the contactor (K3) ON by the PLV output
(Q4) to charge the batteries.
All these operations are performed by a software prepared in PLC.
As shown in Fig.2 in PLC software ladle diagram when I5, I3 are in
high state and Q2 in low state, AUX marker M1 gets high and it will
high output Q1 and machine running in normal state through the
contactor K1.
As soon as power fails, I5 input comes to low logic, so the marker
(M1) gets low and Q1 also gets low logic, as soon as K1 drops to low
state I2 input comes to high logic because I2 coming from N-C
contact. The Marker M2 gets high logic and it will make ON the
output Q2 to make energized . The contactor K2 to connect the motor
through battery supply. The output Q2 is dependent on OFF delay
timer (T1) as time constant setting and stop the motor by the battery
operation.
As shown in Fig. 3- Real time clock (1) used in series with I5 to
operate output Q4 time to time daily from Monday to Sunday to
charge the batteries as per given the clock parameters.
WE CLAIM :
1. An auto-control device to retract cutting tool of an operating CMC-
lathe during power failure, comprising :-
- at least one micro-Controller based programmable logic Controller (PLC)
connected at terminal L and N to a 220V, Ac uninterrupted power supply
(UPS), the power supply is further connected to a common point of a
plurality of outputs (Q1, Q2, Q4) to operate a plurality of contactors (K1, K2,
K3), the other end of the PLC being connected to a plurality of inputs (I1
to 16) of corresponding number of relays, wherein, the Q1 output is used
to operate a drive connected to the contactor (K1) during normal
operation, and wherein the Q2 out put is used to operate the contactor
(K2) during power failure at the machine, the Q4 output operates the
contactor (K4) for battery charging at a defined time by the PLC.
2. The auto-control device as claimed in claim 1 wherein auto control
device is based on a micro PLC.
3. The auto control device as claimed in claim 2 wherein the two
numbers heavy duty batteries used to operate the X axis DC servo
motor by the battery for a brief defined times set by the PLC to take
out the X axis away from the job during power cuts at the machine.
4. The auto-control device as claimed in claim 3 wherein one number +
24V, 5A, SMPS power supply used for battery charging as per defined
clock parameter.
5. The auto control device as claimed in claim 3 wherein a real time
clock (1) used in series with the input (I5) to operate the output Q4.
6. The auto-control device as claimed in claim 1 wherein at least two
relays (RL1, RL1) are disposed parallel to each other, and functioning
during ON Load and OFF LOAD power situation.
7. An auto-control device to retract cutting tool of CMC-lathe during
power failure while in operation as substantially described herein and
illustrated with reference to the accompanying drawings.