Civil Engineering Reference
In-Depth Information
• The analytical model coupled with the experimental observations can be used to
estimate the pulse parameters required for certain reductions in the forming load.
• A model was created to account for the reduction of springback effect in EAF
bending as a function of process parameters.
11.2 Electrically Assisted Machining
The EAM technique has not previously been applied to machining; however, based
on the results seen in EAF, the potential exists to alter the machinability and manu-
facturing processes employed for difficult-to-machine materials. Only brief pre-
liminary testing has been conducted in this area, in which strain rates much lower
than typical machining rates were used. These preliminary electrically assisted tests
yielded improved surface quality of the workpiece and reduced machining forces.
The application of electrically assisted machining holds opportunities to improve
the conventional machining method through the possibility of enabling higher mate-
rial removal rates, reduced cutting forces, modified tool wear, and improved work-
piece surface properties.
11.2.1 Observations in Low-Strain-Rate EA Machining
Initial testing has been conducted in this area using strain rates much lower than
typically found in machining. The electrically assisted machining approach was
applied to a skiving-type machining operation while applying direct current
flow from the cutting tool to the metallic workpiece. The results of the electrical
machining test were compared against a baseline model, without electrical current
flow. The electrically assisted test yielded improved surface quality of the work-
piece and reduced machining forces. Below is a brief description of the experi-
mental setup, results, and findings from this research.
11.2.1.1 Experimental Setup
Preliminary electrically assisted machining tests were performed to investigate the
effect of electrical current on machining. As shown in Fig.
11.21
, direct current (DC)
was applied directly through the cutting tool into the workpiece across the cutting
zone. Relative motion between the tool and workpiece is achieved by linear motion.
The feasibility prototype was constructed for a skiving-type operation of an
A2 Tool Steel workpiece, where the tested surface speed was 16.93 mm/s, which
is significantly lower than typical machining surface speeds. However, this was
an initial test and its purpose was to simply explore possibilities for electrically
assisted machining. The forces were measured with and without electric current
applied, and the resultant surfaces examined for topography.
