The invention relates to a coolant system for machine tools, comprising a pump for the coolant, at least one consumer, a pressure sensor for detecting an actual pressure in the coolant system, a feedback control device acting upon the pump for regulating the pressure in the coolant system to a target pressure, and a limiting valve for limiting the pressure of the coolant supplied to the consumer.
In machine tools there are typically used a plurality of different tools in one processing cycle. Each tool needs to be cooled by supplying a liquid coolant as long as the tool is in use. Since the demand for coolant is different from tool to tool, manufacturers of the tools specify for each tool a specific target pressure which the coolant system must provide.
In a coolant system of the type that has been described above, the pressure in the system is detected by means of a sensor, and the pump is regulated so as to maintain the prescribed target pressure. The limiting valve only serves as a safety valve and has a fixed opening pressure which is significantly larger than the highest possible target pressure. In this system, the pump may react upon changes of the demand for pressure only relatively slowly, so that, in specific cases, especially in cases where the demand for coolant decreases abruptly because, e.g., one of the consumers has been switched off, pressure surges may occur that are undesirable although they remain below the opening pressure of the safety valve.