High-Pressure Unit for Supplying Cutting Fluid in High-Speed Grinding
Abstract Generated abstract
This paper addresses the problem of inadequate cooling in high-speed grinding, where increased heat generation can contribute to burns, cracks, and residual stresses in the workpiece. It argues that conventional free-flood cutting fluid supply is ineffective because of low pump capacity and insufficient jet pressure to penetrate the air wedge at the wheel-workpiece contact zone. The authors describe a high-pressure cutting fluid supply system designed for a modernized 312M cylindrical grinding machine, using a vane pump, filter, electromagnetic spool valve, throttle control, and rectangular nozzle to deliver fluid directly into the cutting zone. The unit can operate with different fluids at pressures up to 30 kg/cm² and flow rates up to 50 l/min.
Full Text
HIGH-PRESSURE SYSTEM FOR SUPPLYING CUTTING FLUID IN HIGH-SPEED GRINDING
V. A. GOVORUKHIN, B. F. SHERKUNOV
(Presented by the scientific seminar of the Department of Machine Tools and Metal Cutting and of Mechanical-Engineering Technology)
The use of high-speed grinding, as shown by the results of studies carried out [1], other conditions being equal, leads to greater heat generation in the cutting zone. High temperatures developing at the point of contact between the grinding wheel and the workpiece have a significant effect on the appearance of grinding burns, cracks, residual stresses, etc. Therefore, successful introduction of high-speed grinding depends to a considerable extent on the effectiveness of accelerating heat removal from the cutting zone and reducing heat generation to a minimum. The currently widely used method of supplying cutting fluid by “free flooding” is ineffective for the following reasons:
— the low capacity of the electric pump (10–15 l/min) is insufficient for effective cooling;
— the low pressure of the fluid jet (0.3–1.2 kg/cm²) cannot overcome the “air wedge” (the zone of contact between the wheel and the workpiece), the pressure in which, even at a grinding speed of 35 m/sec, reaches 8.4 kg/cm² [2].
A high-pressure system for supplying cutting fluid was designed and manufactured for a model 312M cylindrical grinding machine, modernized for high-speed grinding (up to 70–80 m/sec). On the upper panel 1 (Fig. 1) of tank 2 there is installed an electric motor 3 ($N = 5.5$ kW, $n = 1500$ rpm), connected by a coupling to a vane pump 4 ($P = 63$ kg/cm², $Q = 50$ l/min). The fluid from the pump is supplied under pressure through a plate filter 5 and an electromagnetic control spool valve 6. A throttle 7 is provided for regulating the fluid flow rate.
The fluid is supplied directly into the cutting zone by a special nozzle of rectangular cross section. At constant flow rate, the pressure of the fluid jet is regulated by changing the width of the nozzle with the aid of gaskets.
The high-pressure system makes it possible to use various types of fluids and to operate at pressures up to 30 kg/cm² with a flow rate of up to 50 l/min.
REFERENCES
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W. König. High-speed grinding. Express information, “Cutting Tools,” 1971, No. 28.
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L. V. Khudobin. Ways of Improving Grinding Technology. Saratov, 1969.
Fig. 1. General view of the high-pressure installation
for supplying cutting fluid