JP2011096212A - Position sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems that a position sensor must perform signal transmission in a cordless manner when used, for example, in a machine tool with ATC (automatic tool changer) function, and an electromagnetic induction system adapted conventionally as the signal transmission system therefor has trouble with the attachment position or space of an electromagnetic coil, a radio system has trouble by interference, and an infrared system has trouble by external adverse environment. <P>SOLUTION: In the machine tool, a faint AC signal is applied using a connected structure as a floating medium, and an oscillating circuit contained in the position sensor is magnetically coupled with a receiving circuit provided in the machine tool, whereby the signal transmission between the position sensor and a receiver is performed in a cordless manner. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a position sensor capable of transmitting a signal cordlessly, for example, by being attached and detached by an ATC (automatic tool changer) function mounted on a machining center.

Conventionally, as a signal transmission method of a cordless position sensor, an electromagnetic induction (inductive) method, a radio wave (radio) method, and an infrared (optical) method are known.
The outline and problems of each method are described below.

  The electromagnetic induction method is a method in which a transmission coil provided in a position sensor and a reception coil provided in the periphery of a main spindle of a machine are used to transmit a signal through a slight gap in a cordless (non-contact) manner. The transmitter coil provided on the position sensor side requires a mounting part on the side of the position sensor, and the receiver coil must be installed in a limited space around the machine spindle. And retrofit is difficult.

  The radio wave method is a method of transmitting a signal with a radio wave between a transmitter and a receiver incorporated in a position sensor. There are problems with interference between radio waves due to the frequency used, radio interference due to external noise, and there are legal restrictions. In addition, since the transmitter in the position sensor requires a large amount of power, maintenance is troublesome depending on the life of the battery as the power source.

  The infrared method is a method in which signals are transmitted by infrared light using a light emitting unit incorporated in a position sensor and a light receiving unit of a receiver. Since the infrared transmission system has a limited transmission / reception area, the position sensor used in the main shaft movable range in the machine needs to be installed such that the transmission / reception devices are in positions where the lines of sight are good and the transmission areas overlap. In addition, the use condition is that there is no obstacle between the transceivers. For this reason, it is necessary to provide a light emitting unit with a built-in position sensor in the entire peripheral direction, and a plurality of receivers may be required. Further, there is a risk that signal transmission may be hindered by chips, dust, and the like adhering to the visible surface of the light emitting / receiving unit. The light emitting power source in the position sensor is a battery, and it takes time to maintain depending on its life.

  As a cordless signal transmission method other than the electromagnetic induction method, the radio wave method, and the infrared method, there is an AC signal detection device that detects an AC signal with high sensitivity. (Patent Document 1)

  About the form of a position sensor, there exists a touch sensor shown in patent document 2 by which the applicant is the same as an example. The position sensor according to the second aspect of the present invention is not limited to this form, in which the square contact is changed to a spherical shape in accordance with the object to be measured.

Japanese Patent Application No. 2007-21120 Patent No. 296710 RENISHOW general catalog issued in November 2006 There is an illustration of the conventional method.

  The present invention is intended to solve each of the problems in the electromagnetic induction system, radio wave system, and infrared system described above.

  In order to achieve the above object, the present invention does not adopt a conventional electromagnetic induction method, radio wave method, or infrared method as a signal transmission method, and interprets a structure (mainly a machine tool) connected to a machine as a floating conductor. However, signal transmission is performed using the floating conductor as a medium.

  As described above, in the position sensor of the present invention, there is no restriction on the installation location of the receiver. There is no need to provide a large number of light emitting units in the position sensor. The effect of obstacles can be avoided. Do not be affected by chips, dust, etc. By suppressing power consumption, it is possible to provide a position sensor having advantages such as extending the life of a built-in battery. In addition, the communication range can be limited by adopting communication using a very weak AC signal. By appropriately selecting the frequency of the AC signal and the magnetic coupling conditions, it is possible to obtain advantages not found in conventional communication methods such as being resistant to noise in the factory environment.

  The above-mentioned effect is noticeable in a three-dimensional touch probe in a machine tool equipped with an ATC (automatic tool change system).

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is an image diagram showing the overall configuration of the present invention. Reference numeral 1 denotes a mechanical apparatus as an example of a machining center. Reference numeral 2 denotes a connected structure, which is a main spindle portion that holds and rotates a tool and a three-dimensional touch probe 3, and a cord is used for input / output of the touch probe 3 because it needs to be attached and detached by an ATC device (not shown). I can't. A finger (contactor) 4 attached to the touch probe 3 contacts the workpiece 5 and transmits an output signal. A receiver 6 is fixed to the mechanical device 1. Reference numeral 7 denotes a numerical controller of the mechanical device.

  FIG. 2 is a sectional view of the position sensor, and shows the internal configuration of the three-dimensional touch probe described in claim 2. As shown in FIG. 1, the three-dimensional touch probe 3 is attached to a main shaft of a connected structure 2 such as a machining center or a lathe via a shank 8 and is used for centering, dimension measurement, and dimension confirmation of the workpiece 5. Is done. These values are obtained by an electrical signal generated when the finger 4 comes into contact with a workpiece or a tool and the switch contact portion 9 with a built-in three-dimensional touch probe opens and closes. By connecting the contact portion 9 to the transmission circuit 10, communication is performed between the three-dimensional touch probe and the receiver 2 attached to the mechanical device. Power for the transmission circuit is supplied from a battery 11 built in the three-dimensional touch probe. The switch built in the three-dimensional touch probe is not limited to a position sensor type such as a contact sensor, a contactless sensor, or a non-contact sensor.

  Overall configuration diagram   Configuration diagram of 3D touch probe

1 Mechanical device 2 Linked structure (main shaft)
3 Three-dimensional touch probe 4 Finger 5 Work piece 6 Receiver 7 Numerical control device 8 Tapered shank 9 Contact portion 10 Transmitter circuit 11 Battery

Claims (2)

  In the signal transmission between the transmitter and receiver of a position sensor that detects the position of one point in a one-dimensional or three-dimensional manner, no code is used, and no electromagnetic induction method, radio wave method, or infrared method is used. A position sensor characterized by interpreting the structure as a floating conductor and performing AC signal detection transmission using the floating conductor as a medium.   The position sensor according to claim 1, represented by a three-dimensional touch probe used in a machine tool equipped with an ATC (automatic tool change system) function.

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