JP2007229863A - Contact detection device for machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact detection device for a machine tool suitable for a system to sense contact of a measuring probe with a work processed while the spindle is rotated for rotating the probe. <P>SOLUTION: The probe 26 of this contacting detection device is attached to a holder 21, while the probe 26 is held being insulated by a sleeve 25 from the body of the holder 21, and an electric conductive collar 22 to feed current to the probe 26 is insulated from the body 21 fitted by an insulating collar 23. A current feeding brush 35 advances and retreats relative to the electric conductive collar 22, and a current feeding brush 33 is put in slide contact with the collar 22 so as to feed the current to the probe 26 rotating. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention electrically detects contact between a measuring element of a measuring head mounted on a main spindle of a machine tool by exchanging a tool and a workpiece while the measuring element is rotated by the main axis and insulated from each other. The present invention relates to a contact detection device for a machine tool.

  In a machine tool that uses a rotating tool to perform cutting or grinding, attach a probe to the spindle, detect the contact position of the probe by moving the probe and workpiece relative to each other, Based on this, it is widely performed to determine the relative position of the spindle to the workpiece. Based on the detected plurality of relative positions, the shape, dimensions, pitch, hole inner diameter, etc. of the workpiece are measured, or the coordinate system of the workpiece is set.

  There are several methods for detecting the contact position between the probe and the workpiece. Specifically, for example, the measuring element and the workpiece are detected by detecting a change in voltage or current by bringing the measuring element insulated from the workpiece into contact with each other in a state where a predetermined voltage is applied. Is detected, and the relative position of the spindle relative to the workpiece is obtained from the position coordinate value at that time. For example, as shown in Patent Document 1, there is a method of detecting the contact position from the displacement of the detector and the current position. There are merits and demerits in detecting the contact position between various measuring elements and the workpiece, but a detailed description thereof will be omitted.

  By the way, as shown in the above-mentioned Patent Document 1, in recent years, a measuring head having a probe is automatically attached to a spindle of a machine tool used for processing a workpiece using an automatic tool changer (ATC). The method is being implemented. In this way, when attaching a probe with an automatic tool changer, errors may occur in the positions of the main axis and the detection part at the tip of the probe in the horizontal direction (X axis and Y axis) regardless of the difference in the contact detection method. High nature. Therefore, so-called calibration is used to measure the position error of each axis direction between the spindle and the detection part at the tip of the probe using a reference sphere mounted and fixed on the same table as the workpiece for each measurement. Need to be done. Further, when the position error is measured by performing calibration, it is necessary to move the measuring element relative to the same direction as the direction of calibration to bring it into contact with the workpiece. Therefore, time and labor are required for positioning. As a result, a considerable amount of time is required for measuring the shape of the workpiece and setting the coordinate system, thereby reducing workability.

  In view of this, the present applicant has proposed a method of contacting the workpiece while rotating the gauge head in the case of the method of electrically detecting the contact between the gauge head and the workpiece. If the contact position can be obtained by contacting the workpiece while rotating the probe, the tip of the probe is located at the same distance from the main axis regardless of the direction of the tip of the probe. Contact with the workpiece. Therefore, the direction in which the measuring element is brought into contact with the workpiece is not considered. Therefore, it is not necessary to perform calibration every time positioning is performed, and the time required for positioning can be shortened.

  When rotating a measuring element, the structure which applies a voltage to the rotating measuring element is requested | required. However, since there is no proposal to detect contact between the probe and the workpiece while rotating the spindle and rotating the probe, an appropriate configuration for supplying power to the power supply is not shown. Therefore, it is conceivable to use a power feeding method in which a voltage is applied between the tool and the workpiece for the purpose of detecting a load applied to the tool which is widely known.

  Unlike the measurement method described in Patent Document 1, as a general power supply method configuration, for example, a power supply brush as disclosed in Patent Document 2 is provided to supply power to the tool from the outside of the main shaft through the main shaft. Are known. Moreover, as shown in Patent Document 3, there is a configuration in which power is supplied from an energizing brush that makes contact at the center of the rotating shaft at the rear end portion of the main shaft.

JP 7-204990 A Japanese Utility Model Publication No. 5-72355 Japanese Utility Model Publication No. 5-74747

  However, in the energization method described in Patent Documents 2 and 3, current flows from the energizing brush to the tool through the conductive main shaft. Therefore, stray inductance and stray capacitance are increased. For this reason, when the power supply system configured is used in a measurement system that electrically detects contact with the workpiece, sparks are generated because the stray capacitance is large when the tip of the probe contacts the workpiece. Otherwise, there is a risk of damaging a precisely manufactured probe. Further, since the inductance is large, a detection delay occurs and the contact position cannot be detected with high accuracy.

  An object of this invention is to provide the contact detection apparatus for machine tools suitable for the system which detects the contact of a measuring element and a workpiece while rotating a main axis | shaft and rotating a measuring element.

  The present invention relates to a holder, a measuring element attached to the holder, an insulator that insulates the main body of the holder from the measuring element, a conductive collar that is insulated from the main body of the holder and energizes the measuring element, and contacts the collar An energizing brush. Preferably, the measuring element is attached to the holder so as to be displaced in the axis (Z-axis) direction within a predetermined length range.

  Further, the present invention provides a contact detection device for machine tools that contacts a rotating measuring element and a workpiece and electrically detects contact between the measuring element and the workpiece, and is attached to and detached from the spindle by an automatic tool changer. The holder includes a holder that can be insulated and attached to the measuring element, a conductive collar that is insulated from the main body of the holder and energizes the measuring element, and an energizing brush that can move back and forth in contact with the collar. Preferably, the energizing brush is advanced and retracted by an air cylinder.

In addition, the present invention attaches a measuring head to the main spindle of an NC machine tool, applies a voltage between the contact of the measuring head and the workpiece of the object to be measured while rotating the main spindle, In a contact detection device for machine tools that detects contact accuracy due to relative movement and measures the shape accuracy and dimensions of the workpiece,
A collet holder having a hole for coaxially attaching an axial measuring contact on the axial front end side, and having a detachable part to the spindle of the machine tool on the rear end side;
A funnel-shaped conductive contact collar that is provided with an insulating collar on the body of the collet holder and is fitted on the tip side; and
The measuring contact inserted into the mounting hole on the tip side of the collet holder is a cylindrical and conductive contact slider inserted through an insulating and cylindrical sleeve fitted and fixed in the mounting hole. In addition, a measurement head is formed by inserting a shock contact spring at the rear end portion so that it slides coaxially, and a tip contactor protrudes from the slider tip,
Further, energization of the measuring contact is performed by a brush arm in which a contact brush provided in an insulated manner is attached to a portion on the tip side of the main shaft in a state where the measuring head is mounted on the main shaft of the machine tool by a tool changing means. The contact brush comprises an axial advance / retreat driving means, and the contact brush is slidably contacted and separated by the advance / retreat.

  The present invention has a configuration in which the probe is insulated and attached to the holder, and a power supply brush is brought into contact with a conductive collar that is insulated from the holder body and energizes the probe. Is insulated. Therefore, it is not necessary to insulate the workpiece side, and the workpiece can be easily attached. As a result, the workability is improved. Further, since the energizing distance between the energizing brush and the measuring element is made as short as possible, the stray inductance is small and the detection delay is extremely small. As a result, the contact position detection accuracy does not decrease. In addition, since there is no conduction to the main shaft side, the stray capacitance around the probe is reduced, and no spark is generated when the probe is brought into contact with the work piece to make it difficult to damage the probe.

  When the probe is attached to the holder so as to be displaced in the axial (Z-axis) direction within a predetermined length range, the probe is less likely to be damaged when it comes into contact with the workpiece. At this time, since the contact between the probe and the workpiece is electrically detected and the detection delay is small, the detection delay is small due to the displacement of the probe. Absent.

  Further, according to the present invention, the measuring tool is attached to a holder that can be attached to and detached from the main shaft by an automatic tool changer, and the measuring tool is fed with an energizing brush that is in contact with a conductive collar that is insulated and energizes the measuring tool. , Automatic positioning can be performed. Further, since the rotating probe can be supplied with power, it is not necessary to consider the direction of the probe when positioning, and positioning can be performed in a short time. And since a measuring element is insulated and attached to a holder, and it is the structure which contacts an electrically-conductive brush and is insulated from the holder and supplies with electricity, the measuring element and a main axis | shaft are insulated. . Therefore, it is not necessary to insulate the workpiece side, and the workpiece can be easily attached. As a result, workability and work efficiency are improved.

  In addition, since the holder insulated from the probe is mounted on the main shaft, the energization distance between the energizing brush and the probe is made as short as possible, the stray inductance is small, and the detection delay is extremely small. As a result, the contact position detection accuracy does not decrease. In addition, power is supplied to the probe through the collar that is insulated from the holder and is not connected to the spindle, so the stray capacitance around the probe is reduced, and a spark is generated when the probe contacts the work piece and becomes conductive. Do not damage the probe.

  FIG. 1 is a partial cross-sectional view of an embodiment in which a measurement head portion having a contact of a contact detection device for a machine tool according to the present invention and a current-carrying means for the measurement head portion are arranged and attached to a tip end portion of a spindle 2A to 2G show component parts of the measuring head portion, and FIGS. 3A to 3E show the main parts of the energizing means portion. Since the component parts diagrams are shown, the present invention will be described with reference to FIGS.

  A measuring head 10 having a contact 26 as a measuring element is attached to the main spindle 1 of the NC machine tool, and a voltage is applied between the contact 26 and a workpiece (not shown) while the main spindle 1 is rotated as desired. (Normally a relatively low voltage AC voltage) is applied, and the relative movement of both of them (relative movement to the three axes including the xy 2-axis or the Z-axis) is detected to detect contact and separation, It measures dimensions and the like.

  The collet holder 21 having a cylindrical trapezoidal one end and a truncated cone part on the front end side has a hole 21A for coaxially attaching a shaft-shaped measuring contact 26 described later on the front end side, and a machine tool on the rear end side. And an attaching / detaching mechanism portion for attaching and replacing the tool and the measuring head 10 with the ATC apparatus. Also, a contactor collar made of a funnel-like conductor that is fitted over the truncated cone portion so that a current-carrying brush, which will be described later, is in sliding contact with the distal end side of the collet holder 21 and is energized in the rotating state. In order to insulate the collet holder 21 from the contactor collar 22, an insulator collar 23 is provided in the gap between the body of the collet holder 21 and the contactor collar 22 so as to connect and fix them. It is installed.

  The hole 21A of the collet holder 21 of the measurement contact 26 is attached by inserting and fitting a contact sleeve 24 made of an insulator into the hole 21A, while the measurement contact 26 is a cylindrical contact made of a conductive material. A contact sleeve in which an impact interference spring 27 having a spring pressure adjusting bolt 28 is inserted at the bottom end of the hole 21A of the contact sleeve 24 in a state where the slider 25 is inserted so as to slide and slide coaxially. 24, and when the measuring contact 26 protruding from the tip of the contact slider 25 comes into contact with the work piece, the contact 26 is retracted by the axial retreat and shock absorption is measured. is there.

  In the above-described case, the contact slider 25 is firmly fitted in the straight portion of the funnel-shaped tip of the contact collar 22 to ensure electrical conduction between the contact slider 25 and the contact slider 25 and the measurement contact 26. The energization between them is also sufficiently maintained by the axial movement in the sliding contact state of the latter outer peripheral surface with respect to the former inner peripheral surface. Further, the insulation of the contactor collar 22 on the front end side of the collet holder 21 is such that the front end of the contactor sleeve 24 made of an insulator projects a predetermined length from the front end edge of the hole 21A of the collet holder 21 as shown in the figure. By being configured, it is reliably held. In addition, it is natural that the energization between the contact slider 25 and the contact 26 and the collet holder 21 via the spring 28 and the adjusting bolt 27 is insulated by an appropriate insulating means.

  In the aspect in which the measuring contact 26 is attached to the main spindle of the machine tool by the collet holder 21 by the tool changing means, energization from one power supply terminal through the contact collar 22 and the contact slider 25 is performed by the main spindle. 1 is provided with an axial advance / retreat means 33, for example, an air cylinder advance / retreat means, which is provided by being insulated by an insulator 32 via a mounting means 31 on a front end side portion, for example, a side surface of the front end. The contact brush 35 that is in sliding contact with the taper surface 22A of the contact collar 22 in parallel or at a slight inclination is provided with a brush arm 34 that enables adjustment of the sliding contact state by changing the curvature. Mounted and held.

When positioning is performed using the contact detection device for a machine tool according to the embodiment, the collet holder 21 for positioning to which the measuring contact 26 accommodated in the tool magazine is attached is taken out by the automatic tool changer. It is attached to the main shaft 1 by an attaching / detaching means (not shown). Next, the spindle 1 is rotated at, for example, 2000 min ⁻¹ to rotate the measuring contact 26, and the runout width of the measuring contact 26 is measured with a runout measuring instrument attached and fixed to the table.

  Once the rotation of the main shaft 1 is stopped and the air cylinder 33 is operated, the energizing brush 35 is pressed against the side surface of the contact collar 22 and the tapered surface 22. Then, a predetermined AC voltage is applied from the energizing brush 35 through the collar 22. At this time, since the main body 21 and the collar 22 are insulated by the insulating ring 23, and the contactor 26 and the main body 21 are insulated by the insulating sleeve 24, there is no need to insulate the workpiece side, and the floating capacitance or floating Inductance can be reduced.

  Thereafter, while rotating the spindle 1 and rotating the contact 26, the contact 26 and the workpiece are relatively moved in the horizontal direction and brought into contact with each other at a relatively high speed (20 mm / mim). When it is electrically detected that the contact 26 is in contact with the workpiece by looking at a change in voltage or current, the movement is immediately stopped. Then, it is moved back several mm in the direction opposite to the contacted direction. At this time, the current position is acquired and stored in the storage device of the numerical controller.

  Similarly, while rotating the spindle 1 and rotating the measurement contact 26, the contact 26 and the workpiece are moved in the horizontal direction and brought into contact with each other at a relatively medium speed (5 mm / min). Then, the contact between the contact 26 and the workpiece is electrically detected, and the contact position is stored in the storage device. Similarly, while the main shaft 1 is rotated and the contactor 26 is rotated, the contactor 26 and the workpiece are moved in the horizontal direction and brought into contact with each other at a relatively low speed (2 mm / min). Then, the contact between the contact 26 and the workpiece is electrically detected, and the contact position data is stored in the storage device. The relative position is determined by subtracting the offset data obtained by the runout measurement from the contact position data obtained by averaging the contact position data thus obtained.

  The present invention is applied to a machine tool such as a cutting machine or a grinding machine. INDUSTRIAL APPLICABILITY The present invention can electrically detect contact between a measuring element and a workpiece while rotating the contact element, thereby shortening the time required for positioning and improving working efficiency.

It is a side view which shows the main structure of the measurement head part and electricity supply means of embodiment of this invention partially in a cross section. (A) thru | or (G) are each component drawings which comprise the measurement head part of FIG. (A) thru | or (E) are main components figure which comprises the electricity supply means part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main shaft 21 Collet holder 22 Conductor collar 23 Insulator collar 24 Insulator contact sleeve 25 Conductor contact slider 26 Measuring contact 27 Impact interference spring 28 Spring pressure adjusting bolt 31 Mounting means 32 Insulator 33 Air slider 34 Brush arm 35 Electric contact brush

Claims (4)

  A holder, a measuring element attached to the holder, an insulator that insulates the main body of the holder and the measuring element, a conductive collar that is insulated from the main body of the holder and energizes the measuring element, and the collar A contact detection device for a machine tool, comprising a current-carrying brush that makes contact.   The contact detection device for a machine tool according to claim 1, wherein the measuring element is attached to the holder so as to be displaced in a main axis direction within a predetermined length range.   In a contact detection device for a machine tool that contacts a rotating measuring element and a workpiece and electrically detects contact between the measuring element and the workpiece, the tool can be attached to and detached from the spindle by an automatic tool changer. A contact detection device for a machine tool, comprising: an insulated mounting holder; a conductive collar that is insulated from the holder main body and energizes the measuring element; and a forward and backward energizing brush that contacts the collar. A measuring head is mounted on the main spindle of an NC machine tool, and a voltage is applied between the contact of the measuring head and the workpiece of the measurement object while the main spindle is rotated, and the contact and separation due to relative movement of both of them is applied. In contact detection devices for machine tools that detect and measure the shape accuracy and dimensions of workpieces,
A collet holder having a hole for coaxially attaching an axial measuring contact on the axial front end side, and having a detachable part to the spindle of the machine tool on the rear end side;
A funnel-shaped conductive contact collar that is provided with an insulating collar on the body of the collet holder and is fitted on the tip side; and
The measuring contact inserted into the mounting hole on the tip side of the collet holder is a cylindrical and conductive contact slider inserted through an insulating and cylindrical sleeve fitted and fixed in the mounting hole. In addition, a measurement head is formed by inserting a shock contact spring at the rear end portion so that it slides coaxially, and a tip contactor protrudes from the slider tip,
Further, energization of the measuring contact is performed by a brush arm in which a contact brush provided in an insulated manner is attached to a portion on the tip side of the main shaft in a state where the measuring head is mounted on the main shaft of the machine tool by a tool changing means. A contact detection device for a machine tool comprising an axial advance / retreat driving means, wherein the contact brush is configured to be brought into sliding contact with and separated from the outer peripheral surface of the contact collar by the advance / retreat.

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