Measuring and testing – Vibration – Sensing apparatus
Patent
1996-03-14
1997-09-02
Williams, Hezron E.
Measuring and testing
Vibration
Sensing apparatus
73587, 73 182, 73 184, G01N 2924
Patent
active
056635044
DESCRIPTION:
BRIEF SUMMARY
The present invention refers to a sensor system consisting of a vibration or structure-borne noise sensor device and a receiver device with a transformer-like pair of coils, the system contactlessly transmitting the vibration energy of an electrodynamic or piezoelectric measuring element via a primary coil arranged in said sensor device to a secondary coil of said transformer-like pair of coils, the secondary coil being arranged in the receiver device spaced from said sensor device by an air gap, the receiver device further transmitting the measured and transformed vibration or structure-borne noise measuring signal.
Presently, sensors for structure-borne noise and vibration sensors are known to be used in tool monitoring, the sensors being mounted on a stationary element of a machine. Then, the structure-borne noise signals or the vibration signals have to be transmitted from their point of origin via a plurality of machine elements that are partly translated and/or rotated or may be moved so, whereby the signals must be transmitted via a plurality of points of separation between the machine elements onward to the site of the stationary machine element, where the sensor is located. It is known that vibration signals and in particular structure-borne noise signals, especially those in high frequency ranges, are strongly attenuated in particular at each point of separation between two machine elements, but also in each machine element itself.
Thus, it is an aim of tool monitoring to place the vibration sensors or the sensors for structure-borne noise as close as possible to the site where the processing takes place. Therefore, the sensor should possibly be situated on the workpiece or the tool. Since both the workpiece and the tool are elements that are repeatedly replaced, mounting the sensors on the same is not feasible.
With rotating tools, e.g., drill tools, tapping tools, friction tools or milling tools, the vibration signal or the structure-borne noise signal is transmitted from the tool to the shaft via the tool holding fixture or the chucking device and from the shaft to a spindle housing via a bearing. In prior art, the structure-borne noise sensors are presently mounted on such a spindle housing and the structure-borne noise monitoring has to operate with strongly attenuated structure-borne noise or vibration signals. Moreover, it has to cope with disturbing noise from the beating which often is a roller bearing.
Today, a frequently stated demand is to pick up the vibration or structure-borne noise signal at the workpiece for monitoring the tool. Since the same is frequently replaced, of course, the idea/site for mounting sensors would be the workpiece support or the chucking device for the workpiece. In machining centers, milling or drilling machines, the workpieces are often fastened onto pallets that are transported to the respective cutting tools by means of appropriate carriage guide systems and are transported away after cutting so that workpieces can be loaded onto and unloaded from the pallets outside the immediate machining space. It is possible to mount a vibration sensor or a structure-borne noise sensor at the workpiece fitting or the chucking device or the pallet; however, there is a disadvantage in that, due to the connecting cable, the movement of the pallets or carriages is hindered, if no additional provisions for transmission devices for transmitting the structure-borne noise signal are made. Without such a transmission device, a structure-borne noise sensor can presently only be mounted on the stationary carriage guides, the signal originating from the workpiece being strongly attenuated through the several separation planes between the machine elements themselves. Such intermediate machine elements are, for example, the workpiece supports or the chucking device itself, the pallet, the table with its own guiding units and the components disposed between the table and the guiding units, such as annular spur gears that make it possible to rotate the table relative to its guide mea
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Miller Rose M.
Williams Hezron E.
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