In modern machining centers, inductive sensors are the first choice for monitoring motor spindle clamping processes. As they are integrated into the spindle, they need to be small in size and have a high degree of repeatability to guarantee easy tool changeover at all times. For more efficient, intelligent spindle solutions, Baumer offers a range of powerful miniature sensors. These include the classic version, with three switching sensors, or the intelligent version with one measuring sensor.
In automated machining centers, less than a second elapses between the removal of a tool and its replacement by another in the spindle. These centers must operate as reliably as possible to guarantee maximum machine efficiency. The perfect operation of even the smallest inductive sensors plays a decisive role here. In order for the machining center to run smoothly, the machine control system requires the following information on the state of the chuck: open and no tool gripped, closed and no tool gripped, or closed and tool gripped. Inductive sensors provide this information using three inductive switching sensors or one measuring sensor.
XXL range, miniature detectors
In drive and clamping solutions, the sensor technology is integrated into the motor spindle. In these confined spaces, the sensors have to be as small as possible, yet still be high-performance: that's where Baumer's sensors come in. The Swiss sensor manufacturer is said to have the widest range of micrometrically-accurate miniature and sub-miniature inductive sensors on the market.
The IFRM 03 proximity switch, with its diameter of just 3 mm, is part of this range. It is available in several lengths, the shortest variant measuring just 12 mm. The miniature housing contains all the evaluation electronics needed to manage reproducible switching points and precisely measure analog values. These industrial sensors are also compact, EMC-shielded and comply with protection class IP 67. Heat, oily environments and vibrations, common phenomena in machine tools, have no influence on the sensor. Baumer has decades of experience in the manufacture of miniature sensors.
Measurement replaces switching
An analog inductive distance sensor replaces switching sensors that detect the three positions of the tie-rod. This requires the presence of a cone on the tie rod instead of a plate. The measuring sensor can recognize the position of the tie-rod, and therefore the state of the chuck, by means of a cone connected to the tie-rod. The distances or tension values evaluated in the control system can be assigned to the three tie rod positions.
The use of a measuring sensor offers several advantages: firstly, one sensor takes up less space than three individual switching sensors, and therefore requires less installation work. In addition, the sensor continuously monitors the state of the clamping system. It can also detect a loose or off-center tool during clamping, particularly if there are chips between the spindle and the tool. The presence of swarf can damage the tool or alter the quality of the machined part.
Baumer sensors optimize the reproducible precision of tool clamping. They reduce the risk of tool runout and detect it at an early stage. A measuring sensor enhances the reliability of the clamping system and guarantees machining quality and system availability, thus increasing the overall efficiency rate. Micrometer precision of the sensor, the largest possible detection zone and the lowest possible temperature drift are prerequisites. In this respect, Baumer's small AlphaProx inductive distance sensors offer, according to the manufacturer, "the best performance on the market."
The reliability of the measured values and their high accuracy provide the user with maximum reproducibility when tightening tools. Baumer offers one of the smallest inductive distance sensors on the market: the IF08 analog inductive sensor. This product range features a 16 x 8 x 4.7 mm parallelepiped housing. The housing contains all the evaluation electronics, plus a hole for flexible mounting, even in confined spaces. The measuring distance is 2 mm, with a 0-10 VDC output signal.
Flexibility guaranteed by IO-Link
The IR06 Series miniature inductive distance measurement sensor with IO-Link interface offers even greater flexibility, thanks to a housing just 6.5 mm thick and 46 mm long. The standardized interface makes it easy to integrate the clamping process into the control system. Measured values can be recorded and analyzed on a diagram to quickly detect measurement deviations and facilitate potential error analysis. Even the smallest vibration-related changes in the process can be detected and rectified before damage to the part occurs. In addition, the sensor provides additional diagnostic data, such as sensor temperature, useful for machine tool builders to indirectly detect spindle overheating. The sensor also offers all the advantages of IO-Link, such as easy parameterization and rapid commissioning of a replacement sensor by downloading parameters from IO-Link Master via the parameter server function.
The comprehensive range of miniature inductive sensors offers the user considerable flexibility when it comes to implementing a reliable solution for tool clamping processes. It's up to the customer to choose whether to monitor his clamping process via switching sensors or a measuring sensor.
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