The paper describes Ultrasonic
Inspection of forged Carbon Steel Shell Body for
detection of manufacturing discontinuities using
8 channel Ultrasonic Immersion Testing System.
The basic features of the Immersion Test
System are:
· Simultaneous scanning of Shells
with upto 7 probes.
· Automatic monitoring of test results
· Audio & Visual Alarm for defective
Shells.
· Automatic sorting of the Shells as per
the set acceptance or rejection standard.
· Test result print out with all test details.
· Automatic loading and unloading of Shells.
The paper states in brief About:
· System configuration
· Transducers used in the system
· Setting up and operation of the System.
Introduction:
An On-line automated Ultrasonic Testing System
was designed, developed and delivered by M/s.
Electronic & Engineering Company, Bombay,
for inspection of Shell Body used to manufacture
ammunation for the 155 mm Gun. This paper highlights
the system and the testing technique.
Test
Material :
Forged Carbon Steel, rough machined tubular shell
body. Component weight 40 kg.
Test
Technique :
Testing is carried out using pulse - echo immersion
method. The bottom of the shell is scanned in
radial direction using two stationary probes while
the shell is being rotated. The side wall is scanned
in clock-wise & anti-clock-wise direction
with two line focussed probes for longitudinal
defects. The side wall is also scanned for transverse
defects using forward and reverse oriented spot
focussed probes. These probes scan the shell body
with 10% overlap. The absence or presence of the
shell at the test location is sensed by a spot
focussed probe.
Calibration of the equipment is done with reference
artificial defects of cylindrical hole through
the bottom and inside and outside notches for
the side wall.
Equipment
:
A fully automatic process, after loading on the
infeed conveyor to the-accept/reject stands, with
a capacity to test 40 shells per hour, is achieved
through a custom built material handling system.
The shell to be tested is loaded on the infeed
conveyor from where it is picked up by robotic
arm and placed in the immersion tank for testing.
The job is rotated during the testing process.
After testing the job is taken out of the immersion
tank by another set of robotic arm and placed
on
outfeed
conveyor. Rejected shells are segregated separately
for further investigations. Limit switches, proximity
sensors and a PLC co-ordinate the test process.
Fig. 1 shows the schematic layout of the material
handling system.
The
Ultrasonic Instrumentation is housed in a 19"
Rack Panel. It consists of a 8 Channel Pulser-Receiver
Module Model EMX-88, 8 Channel Dual Gate Module
Model GT-88, Microprocessor for data logging and
print out of test results model MC-88, Audio/
Visual Alarms and Power Supply modules.
All
the probes used are immersion type of 4 MHz frequency.
They are optimumally focused and mounted on manipulators
to suit the area being scanned. Manipulators have
fixed locations to test the area of interest.
The adjustable axis of the manipulator are positioned
by a fine thread screw arrangement. Fig. 2 shows
the orientation of the probes and the area covered
by each of them.
Salient
Features of System:
· Simultaneous scanning of Shells
with upto 7probes.
· Automatic monitoring test results.
· Audio & Visual Alarm for defective
shells
· Automatic sorting of the Shells as per
the set acceptance of rejection standard.
· Test result print out.
· Automatic loading and unloading of Shells.
