Dimensional analysis and ANN simulation of chip-tool interface temperature during turning SS304

OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. No. 4 2021 Fig. 2. Tool-work thermocouple machining setup tailstock was necessary to completely isolate the workpiece from the machine body. In this regard, the revolving center was coated with epoxy gel-coating material and Te fl on insulating plugs (non-conductive material plugs) were used. As the tool holder is in direct contact with the turret and ultimately with the machine body, the different parts of the tool holder that come directly in contact with the cutting tool were coated. The coating material used for the coating of the tool holder (a shim, L-shape lever, packing, and shank body) was epoxy-polyester with a coating thickness of around 20 μ m. Tool and workpiece junction at the time of machining was considered as hot junction while the carbon brush touching the workpiece was cold junction as shown in Fig. 2. The connection leads from the tool were taken through the small opening provided on the tool holder shank. A carbon brush was used to make wiring connections from the rotating workpiece. A special stand and spring-loaded holder were designed and fabricated to maintain a uniform and fi rm contact between the carbon brush and the workpiece as shown in Fig. 2. One end of copper wire was placed between the insert and tool holder and the other end was connected to the voltmeter. One additional copper wire was used for completing the electric circuit. One end of the wire was attached to the carbon brush and the other end to the voltmeter. Copper wire of 1 mm diameter was used for the connection purpose and its length was maintained constant during experiments and calibration. Calibration Setup was developed to establish the relationship between the EMF produced and cutting temperature during machining. Tool-work thermocouple junction was constructed using a long continuous chip and tungsten carbide insert. An electric air heater was used as a heating element for the work- tool junction. It simulated the thermal phenomena in machining. It is reported in the literature that the calibration temperature should be more than half the melting point of the working material ( SS304 melting point: 1,453 °C) [1, 2]. Hence, an electric air heater made of Inconel material having a capacity of 2 KW was selected and it can generate 1,000 °C temperature at red-hot conditions. A standard alumel-chromel thermocouple wire was mounted at the junction of the workpiece and insert. For calibration of the chip-tool interface temperature, initially, the workpiece and tool materials to be calibrated were clamped to ensure the proper contact between it. Then, one end of the copper wire was connected to the tool and workpiece and another end was connected to the voltmeter terminals. The electric air heater was then brought into contact with the junction point to heat the junction point. A standard K-type (chromel-alumel) thermocouple was held at the work-tool junction and connected to the temperature indicator. The whole assembly was kept in a container that was insulated with glass wool to reduce heat losses. The electric heater was turned on and the junction point was heated gradually up to 1,000 o C,