JPH1199450A - Tool length measuring method and device for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool length measuring system of high reliability free to automatically and efficiently carry out tool length measurement of a micro- diametrical tool conventionally considered impossible or difficult to measure by a contact-type sensor in high precision without causing loss and breakage of a knife edge. SOLUTION: An optical noncontact type sensor 51 and a contact type sensor 63 of small contact pressure are doubly provided, a tool 1 is quickly and axially fed at first speed, its head end position is promptly detected by the optical noncontact type sensor 51, the tool 1 is guided to a slightly upper part position of a probe 65 of the contact type sensor 65 of small contact pressure, thereafter, axially feeding speed is changed to second speed, the tool 1 is quietly and slowly made contact with the probe 65 and detected by it, and automatic measurement of tool length is carried out on a machine tool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a tool length of a machine tool for measuring a tool length of a tool mounted on a main shaft of a machine tool such as an NC milling machine or a machining center, particularly a tool having a small diameter.

[0002]

2. Description of the Related Art In recent years, tools with minute diameters made of various shapes and materials, for example, very brittle materials such as diamond, extremely small diameter drills (material, carbide) having a tool diameter of about 0.1 mmφ, and cutting edges However, a machine tool has been developed which performs high-speed, high-precision fine processing using a very sharp engraving half-moon-shaped tool or the like. In such a machine tool, for example, tools necessary for machining are prepared in advance, and the tools are sequentially mounted on the main spindle of the machine tool using an automatic tool changer attached to the machine tool such as an NC milling machine or a machining center. In this way, a desired shape is automatically processed.

As an example of an automatic tool changer for a machine tool, a tool changer for an NC machine tool disclosed in Japanese Patent Application Laid-Open No. 8-174364 filed by the present applicant (hereinafter referred to as "first prior art"). "). This is because the tool transfer arm is not interposed between the tool magazine having a plurality of tool pots for accommodating tools and the main spindle of the machine tool, and the X, Y, and Z axes between the tool magazine and the main spindle of the machine tool are not provided. Armless method for directly changing tools by relative movement in the direction,
Instead of fixing the tool once to the tool holder and exchanging the tool with the tool holder, a holderless method that directly exchanges the tool between the tool magazine and the main spindle of the machine tool without intervening the tool holder This is a tool changer that uses both types.

When a desired tool is directly mounted on a main spindle of a machine tool using the tool changing device described in the "first prior art", the tool changing mechanism requires a tool changing device. Each time, the tool length varies. Further, even when a desired tool is mounted on a main spindle of a machine tool with a tool holder interposed therebetween, the tool length may vary every time a tool is changed depending on the mounting state of the tool holder on the main spindle. Therefore, after changing the tool, the tool length of the tool mounted on the spindle is measured on the machine tool machine, the displacement amount of the tool length is calculated as necessary, the displacement amount is included and corrected, and processing is performed. As a result, high-precision processing is realized.

[0005] As an apparatus for measuring the tool length on a machine tool, as described in the above-mentioned "first prior art",
Provide a contact sensor such as a touch sensor at a predetermined position on the machine tool that does not hinder processing, and after the tool is replaced, bring the tool attached to the spindle into contact with the contact point of the contact detector,
There is known a so-called contact-type tool length measuring device which calculates and obtains a tool length based on a movement amount of a spindle from a reference position to a contact position.

Further, Japanese Patent Application No. 8-14 filed by the applicant of the present invention.
As shown in Japanese Patent No. 0648 (hereinafter referred to as “second related art”), an optical non-contact type detector provided with a light projecting unit and a light receiving unit at a predetermined position which does not hinder processing on a machine tool. Provided, after the tool exchange, move the tool mounted on the spindle to the measurement area of the non-contact type detector, calculate the tool length based on the amount of movement of the spindle from the reference position to the light-shielded detection position, find the
There is also a so-called non-contact type tool length measuring device.

[0007]

A tool having a very small diameter mounted on a spindle after a tool change, for example, a tool made of a material which is very brittle such as diamond as described above, a very small diameter having a tool diameter of about 0.1 mmφ Drills, engraving tools with very sharp cutting edges, etc. (hereinafter referred to as "micro-diameter tools")
Conventionally, the operator measures the tool length by carefully moving the tool manually while rotating the tool at the number of revolutions at the time of machining, and paying careful attention so that the tool edge is not broken or broken. The tool is brought into contact with a reference surface provided on the machine, and the tool length is calculated based on the amount of movement of the spindle from the reference position to the contact position. However, in this case, a person must intervene when measuring the tool length, and it is impossible to automatically perform the process from the measurement of the tool length to the machining. Furthermore, extreme care must be taken during the measurement so as not to break or break the tool edge, and the measurement requires skill and considerable time.

In the case of measuring the tool length of a small-diameter tool mounted on a spindle after a tool change by using an optical non-contact detector as described in the above-mentioned "second conventional technique", Due to the shape of the cutting edge of the tool and the oil film of the cutting fluid adhering to the cutting edge of the tool, the light beam emitted from the light emitting part of the optical non-contact type detector is diffracted (the light passes through the edge of the obstacle. When the tool propagates, it becomes difficult to go straight toward the light receiving part, and a slight error occurs in the light shielding detection position of the tool when measuring the tool length. It becomes difficult to measure the tool length.

In order to avoid the above-mentioned problems, the tool length measurement of a small-diameter tool mounted on the spindle after the tool replacement is performed by using, for example, the contact-type detector described in the above-mentioned "first prior art". It is most desirable to do this. By the way, in recent years, the vibration generating element at the time of moving the feed shaft of the machine tool has increased with the speeding up of the processing, and the contact type detector which is not affected by such vibration, that is, the contact pressure is high (100 to 100).
A detector having a probe is used for measuring the tool length. Further, at the time of tool length measurement, the speed of approaching the tool to the contact element of the contact type detector is increased to shorten the tool length measurement time as much as possible, and as a result, the machining time is shortened. .

However, when measuring the tool length of a small-diameter tool mounted on the spindle after the tool change using a contact-type detector, the contact pressure of the detector, the approach speed of the tool to the measuring element, etc. May cause breakage or breakage of the tool edge when contacting the probe.
Therefore, in order to automatically measure the tool length of a small-diameter tool mounted on the spindle using a contact-type detector, the contact pressure of the measuring element of the contact-type detector must be reduced in advance (20 to 2).
(Approximately 5 g) and the approach speed of the tool to the probe needs to be extremely low. In this case, the tool length measurement time is unnecessarily lengthened, and as a result, the machining time is extended.

An object of the present invention is to solve the above-mentioned problems inherent in the conventional method and apparatus for measuring a tool length, and to measure the tool length of a small-diameter tool on a machine tool in a short time and with high accuracy. An object of the present invention is to provide a method and an apparatus for measuring a tool length of a machine tool which can be performed.

[0012]

In order to achieve the above-mentioned object, an optical tool tip position detecting means and a contact type tool tip position detecting means are provided on a machine tool. The tool is moved at a relatively high feed rate toward the detection means to detect the tip position, and then, from a predetermined position set in advance, the tool is moved at a considerably low feed rate,
The tool is moved toward the contact-type tool tip position detecting means to detect the tip position, and the tool length of the tool is calculated from the tool tip position detected by the contact-type tool tip position detecting means and the reference position of the main shaft. It is something to do. For details,
Each component is provided as described below. (1) In a machine tool for processing a workpiece by relatively moving a tool and a tool mounted on a spindle, an optical tool tip position detecting means and a contact type tool tip are provided at predetermined positions relatively movable with respect to the tool. A position detecting means for moving the tool toward a measurement area of the optical tool tip position detecting means at a first feed speed to detect the tool tip position, and the contact type tool tip position detecting means; The tool is guided to a position separated by a predetermined distance from the measuring element, and the tool is directed from the predetermined position to the measuring element of the contact-type tool tip position detecting means at a second feeding speed smaller than the first feeding speed. The tool tip position of the tool is detected from the tip position of the tool detected by the contact-type tool tip position detecting means and a preset reference position of the spindle. Is a tool length measurement method for machine tools.

(2) In a machine tool for processing a workpiece by relatively moving a tool mounted on a main spindle and a workpiece in response to a feed axis movement command from a numerical control unit, the workpiece is moved to a predetermined position relative to the tool. The provided optical tool tip position detecting means, the contact type tool tip position detecting means having a tracing stylus provided at a predetermined position relatively movable with respect to the tool, and the tool at a first feed speed. While moving toward the measurement area of the optical tool tip position detecting means to detect the tip position of the tool, guiding to a position separated by a predetermined distance from the measuring element of the contact type tool tip position detecting means, A tool is moved from the predetermined position to the contact point of the contact-type tool tip position detecting means at a second feed rate smaller than the first feed rate, and measurement is performed to detect the tip position of the tool. Measurement control means for controlling operation, tool length calculation means for calculating the tool length of the tool from the tip position of the tool detected by the contact-type tool tip position detection means and a preset reference position of the spindle, A tool length measuring device for a machine tool comprising:

(3) The machine tool according to the above (2), wherein the measuring element of the contact-type tool tip position detecting means is disposed substantially below the measurement area of the optical tool tip position detecting means. Tool length measuring device.

[0015]

The operation of the present invention will be briefly described below. By axially feeding the tool after the tool change at the first feed speed, the tool enters the measurement area of the optical non-contact type position detecting means to quickly detect the tip position of the tool, and the tool has a small contact pressure. The guide is guided at the first feed speed to a position in front of the contact point of the contact type position detecting means and close to the contact point. Simultaneously, the tool is moved to a position close to the contact point of the contact type position detecting means before the contact point, and at the same time, the feed speed of the tool is reduced to a second feed speed which is extremely slower than the first speed.

In order to avoid the influence of vibration generated due to the movement of the tool, the detection signal of the contact-type position detecting means is not output until the tip of the tool passes through the above-mentioned location close to the measuring element of the contact-type position detecting means. Enable (start). The tool tip is made to gradually enter the measuring element at the second feed speed from the point close to the contact-type position detecting means, and by adopting the contact-type position detecting means with extremely small contact pressure, When the tip of the cutting edge of the tool comes into contact with the probe, the chip is prevented from being broken or broken.

When a signal indicating that the tip of the tool has contacted the tracing stylus of the contact type position detecting means is input to the feed axis position detecting means, the axis of the tool is stopped, and the signal from the feed axis position detecting means, The tool length is calculated on the machine by the tool length calculation means based on the tool attachment reference position stored in advance. As described above, based on the method and apparatus described above, conventionally, the measurement of the tool length of a small-diameter tool, which is unfamiliar or impossible with the automatic measurement by the contact-type position detection means, is performed without causing any chipping or breakage of the tool edge. , It is possible to measure with high accuracy in almost the same time as the measurement of the normal tool length, including continuous machining, including tool replacement with the micro-diameter tool
High-precision processing without any step on the processing surface has been enabled.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. Some of the constituent elements of the present invention may be appropriately changed within the technical level of the industry at the time of filing the present invention. Therefore, it is not allowed to reduce the scope of the invention based on only the present embodiment. FIG. 1 is a side view and a configuration block diagram of a main part of an embodiment of a tool length measuring device for a machine tool that implements a tool length measuring method according to the present invention. FIG. It is a principal part front view of a tool length measuring device. FIG. 3 is a plan view of an optical non-contact position detecting device which is one of the components of the device.

First, with reference to FIG. 1 and FIG. 2, an essential part of an NC machine tool provided with a tool length measuring device will be described. In the figure, N
On the main body (not shown) of the C machine tool, a spindle 3 on which the tool 1 is mounted is rotatably supported by the spindle head 5 and, based on a command from a numerical controller 69 of the NC device 68, an X-axis feed motor 7,
By driving the Y-axis feed motor 9, the Z-axis feed motor 11, and the spindle rotation motor (not shown), X, X and Y are moved between the spindle head 5 and a table 13 on which a work (not shown) is placed.
Causing relative movement in the three orthogonal directions of the Y and Z axes,
The spindle 3 is rotated within the spindle head 5. A collet chuck 15 for holding the tool 1 is screwed into a lower part of a draw bar (not shown) provided in the main spindle 3, and the draw bar is assembled in the main spindle 3 so as to be movable in the vertical direction together with the collet chuck 15. .

In FIG. 2, a guide 21 is provided on a bracket 19 attached to the side surface of the table 13, and a magazine base 25 is set up on a carrier 23 guided by the guide 21 so as to be able to reciprocate in a direction parallel to the X axis. A tool magazine 17 for housing the tool 1 is fixed on a magazine base 25. The tool magazine 17 is a plate material made of an elastic material such as a resin. The tool magazine 17 has two upper and lower layers in which a groove 17b is formed in an intermediate portion of the plate thickness, and eight tool pots 17a for storing the tool 1 are formed. An elastic ring 27 is fitted to each tool 1. The elastic ring 27 fits into the groove 17b when the tool 1 is stored in the tool pot 17a of the tool magazine 17, and the upper and lower portions thereof are sandwiched. It becomes a rough reference in the axial direction and is held by the tool pot 17a.

A plate 29 attached to the left side surface (see FIG. 2) of the carrier 23 has a cylinder 31
One end of the piston rod 33 is fixed, and by supplying pressurized air to the cylinder 31 to move the rod 33 forward and backward, the carrier 23 is moved along the guide 21 in a direction parallel to the X axis. Magazine base set up on 23
The tool magazine 17 fixed on the top 25 can be reciprocated between a forward position (see FIG. 2) where a tool can be changed and a retracted position outside the work area of the work. A pulley bracket 37 for rotatably supporting the pulley 35 is attached to the right side surface of the plate 29, and a pinion 39 fixed coaxially with the pulley 35 is engaged with a rack 41 attached to the guide 21. The plate 29 has a cover 43 for preventing chips and cutting fluid from adhering to the periphery of the tool magazine 17 during machining.
A magazine cover 47 cooperating with a pulley 45 is coaxially pivotally mounted on the cover 43, and pulleys 35 and
A belt 49 is stretched between the belt 45 and the belt 45.

Normally, the tool magazine 17 is located at the retracted position outside the machining area of the workpiece.
When a tool change command is sent from 69, a tool magazine movement command is sent to the machine control unit 71 to operate the cylinder 31 to retract the piston rod 33, move the plate 29 to the right, and change the tool magazine 17 to the tool change. Advance to position. At the same time, the pinion 39 meshing with the rack 41 attached to the guide 21 and the pulley 35 fixed to the pinion 39 rotate counterclockwise, rotate the pulley 45 counterclockwise via the belt 49, and remove the makajin cover 47. open. In this state, automatic tool change by relative movement in the X, Y, and Z axis directions between the tool magazine 17 and the spindle 3 of the NC machine tool, or manual replacement of the tool 1 stored in the tool magazine 17 is performed. Will be possible.

That is, when the tool 1 mounted on the spindle 3 is stored in the tool pot 17a of the tool magazine 17 at the time of tool change, the collet chuck 15 is projected from the tip of the spindle 3 by pushing the draw bar downward. The tool 1 is unclamped so that the collet chuck 15 is released from the tapered hole at the tip of the spindle. When the tool 1 stored in the tool pot 17a of the tool magazine 17 is to be mounted on the main spindle 3, the draw bar is pulled up to fit the tapered portion of the collet chuck 15 with the tapered hole at the tip of the main spindle 3, so that the collet chuck 15 is engaged. The tool 1 is clamped by applying a gripping force.

At a predetermined position on the table 13 which does not hinder the processing, a line sensor (optical non-contact type detector) 51 for detecting the position of the tip of the tool 1 is provided. here,
The line sensor 51 is not limited to the position on the table 13 and may be provided anywhere as long as the main shaft 3, that is, the position relative to the tool 1 is movable. As shown in FIG. 3A, the line sensor 51 is a sensor base 51 mounted on the table 13.
In a, light from a light source such as a light-emitting diode
Projection unit 51b with built-in lens to convert to 53
a light receiving section 51c in which a plurality of light receiving elements 55 such as charge-coupled devices (CCD) for receiving the light beam 53 emitted from the light receiving section 51b are arranged at predetermined intervals (for example, at intervals of several μm). 51b and light receiving section 51c are arranged so as to face each other. At the time of tool length measurement, the tool 1 reaches a measurement area between the light projecting portion 51b and the light receiving portion 51c of the line sensor 51, and
The light receiving section 51c indicates that the light beam 53 emitted from the
, And is converted into an electric signal.

Although not shown, the sensor base 51
A contact plate for detecting contact with the tool 1 may be provided at the entrance and the bottom of the measurement area a in case of a failure or malfunction of the line sensor 51. When the tool length is measured, chips and cutting fluid scattered from the tool 1 to the measurement area of the line sensor 51 are supplied to the bottom contact plate by the light projecting unit 51b and the light receiving unit.
Even if a plurality of nozzles are provided to blow out the pressurized air upward toward the measurement area so as not to contaminate 51c and also to have the effect of preventing fogging of the light emitting part 51b and the light receiving part 51c. Good. If the pressurized air is also jetted toward the tool 1, it is possible to blow chips, cutting fluid, and the like attached to the cutting edge or the like of the tool 1 out of the measurement area when measuring the tool length.

The sensor cover 57 provided so as to surround the line sensor 51 prevents chips and cutting fluid scattered during machining from adhering to the periphery of the line sensor 51. Pressurized air is supplied to (not shown) to open, and the measurement area of the line sensor 51 is opened to the tool 1. Referring again to FIG. 1, there is a measurement area at a lower position along the axis feed direction (Z-axis direction) of the main shaft 3 with respect to the measurement area of the line sensor 51, and does not hinder processing. At a predetermined position on the table 13, a contact sensor 63 for detecting the position of the tool tip is provided.
Similarly to the line sensor 51, the contact sensor 63 is not limited to being provided on the table 13, and may be provided anywhere as long as it can move relative to the tool 1.

As described above, conventionally, for the purpose of speeding up machining and shortening the measuring time, the measuring approach speed to the contact type sensor for measuring the tool length is increased, and the contact pressure of the measuring element is accordingly reduced. About 100-150g,
It is general that the vibration generated based on the axial feed does not affect the measurement accuracy. However, in the contact type sensor 63 of the present embodiment, the contact pressure of the measuring element 65 is reduced to about 20 to 25 g. It is designed so that the edge of the cutting edge does not break or break when the tip of the tool contacts. Further, the feed speed of the tool 1 entering the measurement area is reduced so that the tool tip gently hits the tracing stylus 65 when measuring the tool length. The contact sensor 63 is also provided with a sensor cover 67 so as to surround the sensor 63 to prevent chips and cutting fluid scattered during machining from adhering to the periphery of the contact sensor 63. When the tool length is measured, air is supplied to a cylinder (not shown) to open the sensor cover 67, and the contact type sensor 63 is opened.
Open the measurement area of.

The control means of the machine tool comprises an NC unit 68 and a machine control unit 71. The numerical controller 69 in the NC device 68 reads and decodes an NC program consisting of a machining program and a tool length measurement program to perform linear interpolation or circular interpolation, and sends a movement command through the servo unit to the X-axis feed motor 7, It sends the rotation command to the Y-axis feed motor 9 and the Z-axis feed motor 11 to control the drive of each axis feed motor and sends a rotation command of the spindle 3 to the spindle rotation motor. Also, N
The machining program of the C program includes a tool exchange command and the like. When a tool exchange command is transmitted in the machining process, the machining is temporarily stopped, the tool magazine 17 is moved, and the spindle 3 is moved in the X, Y, and Z axis directions. Commands such as replacement of the tool 1 by movement are sequentially transmitted to the machine control device 71 according to a program.

The machine controller 71 comprises a measurement controller 73, a tool length calculator 75, a data storage 77, and a feed axis position detector 79. The tool length measurement program of the NC program is stored in the measurement control unit 73, and a tool movement command to the measurement area of the line sensor 51 or the contact sensor 63, a tool approach speed (first feed speed) command to the line sensor 51, is issued. , A tool approach speed (second feed speed) command to the contact point 65 of the contact sensor 63, a position separated from the contact point 65 of the contact sensor 63 by a predetermined distance (the tool approach speed is changed from the first feed speed to the second feed speed) Command for moving the tool to the position of the feed axis that decelerates to

The data storage unit stores the position of the feed axis (calibration data) as a reference for calculating the tool length.
It is obtained and stored in advance before processing.
The calibration data includes the position of the feed shaft when the tip of the main shaft 1 detects light blocking in the line sensor 51 and the position of the feed shaft when the tip of the main shaft 1 detects contact with the measuring element 65 of the contact sensor 63. Position. When obtaining the calibration data, when the tip of the spindle 1 approaches each of the sensors 51 and 63, it is assumed that interference between the spindle 1 and each of the sensor bodies 51 and 63 occurs depending on the outer diameter of the spindle 1. Is done. Therefore, a tool with a known tool length is
And the position of the feed shaft when the tool detects light shielding or contact in each of the sensors 51 and 63 is detected. Based on these detected positions and the known tool length, the tip of the main shaft 1 The position of the feed shaft when light shielding or contact is detected in 51 and 63 is calculated backward.

In the feed axis position detecting section 79, a movement command sent from the numerical control section 69 of the NC unit 68 to each of the axis feed motors 7, 9, 11 via the rotary encoders 8, 10, 12 and the linear scale. The position of each feed axis of the X, Y, and Z axes is read every moment, and when the tool length is measured, the light receiving or contact signals from the sensors 51 and 63 at the tip of the tool 1 are received, and the X, Y, and Z signals at that time are received. The position of each feed axis of the Z axis can be detected. In the tool length calculating section 75, when the tool length is measured, X, X in the feed axis position detecting section 79 when the light shielding or contact by the sensors 51 and 63 at the tip of the tool 1 is detected.
The tool length is calculated from the position data of each feed axis of the Y and Z axes and the reference position data of the tip end of the spindle 1 stored in the data storage unit 77. If necessary, a tool offset amount, which is a displacement amount of the tool length, is calculated and sent to the numerical control unit 69 of the NC device 68 via the measurement control unit 73.

(Embodiment 1) The tool length measuring method of the present embodiment will be described based on the tool length measuring device of a machine tool described above. (1) An elastic ring 27 is fitted to a tool 1 including a plurality of micro-diameter tools used for machining a desired shape, and a tool magazine is provided.
It is stored in 17 tool pots 17a. When another tool 1 is mounted on the main spindle 3, an empty tool pot 17a for returning and exchanging the tool 1 needs to be provided in the tool magazine 17 (see FIG. 1). (2) When a tool change command is sent from the numerical controller 69 of the NC device 68, a tool magazine movement command is sent to the machine control device 71, and pressurized air is supplied to the cylinder 31 (see FIG. 2). The magazine 17 advances to a position where the tool can be exchanged, and the magazine cover 47 is opened. Thereafter, automatic tool change is performed between the tool magazine 17 and the spindle 3 by relative movement in the X, Y, and Z axis directions. Each time, as described above, the collet chuck 15 of the spindle 3 is opened and closed to open and mount the tool 1.

(3) When the tool change is completed, pressurized air is again supplied to the cylinder 31 to retreat the tool magazine 17 to the old position and rotate the magazine cover 47,
Covers tool magazine 17. (4) After the tool change, based on a command from the tool length measurement program stored in the measurement control unit 73 of the machine control device 71,
The tool 1 is positioned on the measurement area of the line sensor 51. (5) Next, the sensor covers 57 and 67 of the line sensor 51 and the contact sensor 63 are opened, and the light beam 53 is emitted from the light projecting portion 51b of the line sensor 51 to the light receiving portion 51c. At this time, the contact sensor 63 has not been activated yet.

(6) The tool 1 is moved toward the measurement area of the line sensor 51 in the Z-axis direction at a feed speed (first feed speed) of, for example, about 2000 mm / min. (7) The light receiving section 51 of the line sensor 51 is
An output obtained by blocking the light beam 53 toward c is sent to the numerical controller 69 of the NC device 68 to temporarily stop or decelerate the movement of the tool 1 in the Z-axis direction. At the same time, the feed axis position detector 79 of the machine controller 71 receives the light-shielded output of the line sensor 51 by the tip of the tool 1 and detects the position of the feed axis (Z axis) at that moment. Thus, the tip position of the tool 1 mounted on the spindle 3 can be obtained. (8) After that, the tool 1 is moved onto the contact 65 of the contact sensor 63 until the tip of the tool 1 reaches a position above the contact 65 of the contact sensor 63, for example, about 50 μm. The tool 1 is again moved in the Z-axis direction at the first feed speed, and at the same time when the same position is reached, the feed speed of the tool 1 is reduced to a considerably low feed speed of about 0.3 mm / min (second feed speed). , And is moved toward the tracing stylus 65 of the contact-type sensor 63. Here, at the same time when the feed speed of the tool 1 is reduced to the second feed speed, the contact type sensor 63 whose contact pressure of the tracing stylus 65 is about 20 to 25 g is activated (the detection output from the contact type sensor 63 is enabled). In this way, the vibration generated by the shaft feed is not affected by the detection accuracy of the contact sensor 63.

(9) Contact type sensor by tip of tool 1
The output contacting the 63 stylus 65 is sent to the numerical controller 69 of the NC device 68 to stop the movement of the tool 1 in the Z-axis direction. At the same time, the feed axis position detecting section 79 of the machine control device 71 receives the contact pressure of the contact type sensor 63 by the tip of the tool 1 and detects the position of the feed axis (Z axis) at that moment.
It is sent to the tool length calculation unit 75. Therefore, the contact sensor 63
Since the tool 1 is axially fed at a considerably low feed speed to contact the probe 65 having a very small contact pressure, there is no risk that the tool edge is broken or broken even with a small-diameter tool. (10) The tip of the tool 1 is detected and sent out by the feed axis position detector 79 of the machine control device 71, and the tip 65 of the contact sensor 63 is
Receiving the position of the feed axis (Z-axis) at the moment when it comes into contact with the feed axis and the reference position data of the feed axis stored in the data storage unit 77, that is, the reference position data of the tip end of the spindle 1.
At 75, the tool length of the tool 1 is calculated.

(Embodiment 2) The laser sensor 59 as shown in FIG. 3B is replaced by a table instead of the line sensor 51 among the components of the tool length measuring method and apparatus described in <Embodiment 1>. Place on 13 and configure. Laser sensor 59
Also, as with the line sensor 51, it is only necessary to be at a position that can be relatively moved with respect to the tool 1. Since the light beam 53 of the line sensor 51 has a width, the most protruding position of the tip of the tool 1 can be detected without rotating the tool 1. Since the light projecting portion 59b of the laser sensor 59 only irradiates one beam-shaped (laser) beam 61 toward the opposing light receiving portion 59c, the tool 1 rotates (normally,
If it is not necessary to enter the measurement area between the light projecting part 59b and the light receiving part 59c of the laser sensor 59 while making the rotation speed in the processing state), the most protruding position of the tip of the tool 1 is detected. It is said that accurate tool length measurement cannot be performed.

Reference numeral 51a denotes a sensor base of the laser sensor 59. Other configurations, for example, sensor cover,
The sensor attachment device such as a contact plate may be understood to be the same as that of the line sensor 51. In the present embodiment, the rotation of the main shaft 3 is stopped at the stage where the tip position of the tool 1 is detected by the contact sensor 63. The other means, configuration, and operation of the tool tip position are as described in the first embodiment.

(Embodiment 3) In the tool length measuring method and apparatus in the above two embodiments, at least an optical non-contact type sensor and a contact type sensor 63 are used in combination.
Conventionally, it has become possible to measure the tool length of a small-diameter tool, which has been difficult with only the contact-type sensor 63, in a short time and with high accuracy without causing breakage or breakage of the tool edge. In this case, from the viewpoint of the tool length measuring method and the configuration of the apparatus, if the optical non-contact type sensor and the contact type sensor 63 are provided along the axis feed (Z axis) direction of the tool 1, the tool 1
Can be moved at once from the measurement area of the non-contact type sensor to the tracing stylus 65 of the contact type sensor 63, and the operation of moving horizontally in the X and Y axis directions and time can be saved.
Obviously, the measurement time can be shortened.

FIG. 4 shows another embodiment in which the elements of the optical non-contact type sensor 51 and the contact type sensor 63 of (Embodiment 1) are repositioned in the vertical direction in accordance with the above-mentioned purpose. FIG. In the drawings, the reference numerals assigned to the sensor constituent members shown in FIGS. 1, 2 and 3 are the same as those described with reference to FIGS. In the present embodiment, the measurement area of the optical non-contact sensor 51,
The tracing stylus 65 of the contact type sensor 63 is overlapped in the vertical direction, and the tip position of the tool 1 can be detected only by moving the tool 1 in the Z-axis direction. Between the measurement area and the probe 65 of the contact sensor 63,
It is not necessary to move the tool 1 in the horizontal and X-axis directions.

The optical non-contact sensor may be a line sensor 51 or a laser sensor 59. The rotation of the spindle 3 corresponds to the type of sensor and is programmed as described above. For other configurations and operations, refer to the description in (Embodiment 1). Although the embodiment of the present invention has been described based on the form of the vertical machining center in which the main shaft rotates around the vertical axis, it goes without saying that the present invention can also be applied to a horizontal machining center in which the main shaft rotates around a horizontal axis.

[0042]

According to the present invention, by automatically providing an optical non-contact type sensor and a contact type sensor having a small contact pressure, the tool length of a small-diameter tool, which has been considered impossible or difficult in the past, can be automatically controlled. Measurement is possible,
Even if the micro-diameter tools are sequentially replaced, the tool length can be accurately measured after the replacement, and high-precision machining can be continuously performed without generating a step on the workpiece machining surface. The tip position of the tool is detected by an optical non-contact type sensor, and it is quickly guided to the contact point of the contact type sensor with a small contact pressure. There is no breakage or breakage of the cutting edge, and the tool length can be accurately and efficiently measured in a short time.
For example, conventional methods and devices cannot be expected.
Functions and effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view and a configuration block diagram of a main part showing an embodiment of a tool length measuring device of a machine tool for implementing a tool length measuring method of the present invention.

FIG. 2 is a front view of a main part of a tool changing device and a tool length measuring device taken along arrow A in FIG.

FIG. 3 is a plan view of an optical non-contact position detecting device.

FIG. 4 is a side view of a main part of another embodiment of a tool length measuring device of a machine tool for implementing the tool length measuring method of the present invention.

[Explanation of symbols]

 1 Tool 3 Spindle 13 Table 51 Line sensor 53, 61 Light beam 59 Laser sensor 63 Contact sensor 65 Measuring element 68 NC unit 69 Numerical control unit 71 Machine control unit 73 Measurement control unit 75 Tool length calculation unit 77 Data storage unit 79 Feed axis Position detector

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 3, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a tool length of a machine tool for measuring a tool length of a tool mounted on a main shaft of a machine tool such as an NC milling machine or a machining center, particularly a tool having a small diameter.

[0002]

2. Description of the Related Art In recent years, tools having minute diameters of various shapes and materials, for example, very brittle tools such as diamond, extremely small diameter drills (material, carbide) having a tool diameter of about 0.1 mmφ, and cutting edges However, a machine tool has been developed which performs high-speed, high-precision fine processing using a very sharp engraving half-moon-shaped tool or the like. In such a machine tool, for example, tools necessary for machining are prepared in advance, and the tools are sequentially mounted on the main spindle of the machine tool using an automatic tool changer attached to the machine tool such as an NC milling machine or a machining center. In this way, a desired shape is automatically processed.

[0003] Here, as an example of an automatic tool changer for a machine tool, Japanese Patent Application Laid-Open No. H8-17436 filed by the present applicant has been proposed.
There is a tool changer for an NC machine tool disclosed in Japanese Patent Publication No. 4 (hereinafter, referred to as "first related art"). This is because the tool transfer arm is not interposed between the tool magazine having a plurality of tool pots for accommodating tools and the main spindle of the machine tool, and the X, Y, and Z axes between the tool magazine and the main spindle of the machine tool are not provided. An armless method in which tool change is performed directly by relative movement in the direction and a tool magazine that is not fixed to the tool holder once and the tool holder is replaced with the tool magazine without the tool holder interposed This is a tool changer that employs both a holderless method and a holderless method in which a tool is directly exchanged with a main shaft of a machine tool.

When a desired tool is directly mounted on a main spindle of a machine tool using the tool changing device described in the "first prior art", the tool changing mechanism requires a tool changing device. Each time, the tool length varies. Further, even when a desired tool is mounted on a main spindle of a machine tool with a tool holder interposed therebetween, the tool length may vary every time a tool is changed depending on the mounting state of the tool holder on the main spindle. Therefore, after changing the tool, the tool length of the tool mounted on the spindle is measured on the machine tool machine, the displacement amount of the tool length is calculated as necessary, the displacement amount is included and corrected, and processing is performed. As a result, high-precision processing is realized.

[0005] As an apparatus for measuring the tool length on a machine tool, as described in the above-mentioned "first prior art",
Provide a contact sensor such as a touch sensor at a predetermined position on the machine tool that does not hinder processing, and after the tool is replaced, bring the tool attached to the spindle into contact with the contact point of the contact detector,
There is known a so-called contact-type tool length measuring device which calculates and obtains a tool length based on a movement amount of a spindle from a reference position to a contact position.

Further, Japanese Patent Application No. 8-1 filed by the applicant of the present invention.
As shown in Japanese Patent No. 40648 (hereinafter referred to as "second related art"), an optical non-contact detector including a light projecting unit and a light receiving unit at a predetermined position on a machine tool that does not hinder processing. Provided, after the tool exchange, move the tool mounted on the spindle to the measurement area of the non-contact type detector, calculate the tool length based on the amount of movement of the spindle from the reference position to the light shielding detection position, so-called, Non-contact type tool length measuring devices also exist.

[0007]

A tool having a very small diameter mounted on a spindle after a tool change, for example, a tool made of a very brittle material such as diamond as described above, a very small diameter having a tool diameter of about 0.1 mmφ Conventionally, the tool length measurement of a drill, an engraving tool with a very sharp edge, etc. (hereinafter referred to as a “micro-diameter tool”) has conventionally been performed by an operator manually rotating the tool at the number of revolutions during machining. Slowly move the tool and make sure that the tool makes contact with the reference surface provided on the machine tool while paying careful attention not to cause chipping or breakage of the tool edge, and the amount of movement of the spindle from the reference position to the contact position The calculation of the tool length is performed based on. However, in this case, a person must intervene when measuring the tool length, and it is impossible to automatically perform the process from the measurement of the tool length to the machining. Furthermore, extreme care must be taken during the measurement so as not to break or break the tool edge, and the measurement requires skill and considerable time.

In the case of measuring the tool length of a small-diameter tool mounted on a spindle after a tool change by using an optical non-contact detector as described in the above-mentioned "second conventional technique", Due to the shape of the cutting edge of the tool and the oil film of the cutting fluid adhering to the cutting edge of the tool, the light beam emitted from the light emitting part of the optical non-contact type detector is diffracted (the light passes through the edge of the obstacle. When the tool propagates, it becomes difficult to go straight toward the light receiving part, and a slight error occurs in the light shielding detection position of the tool when measuring the tool length. It becomes difficult to measure the tool length.

In order to avoid the above-mentioned problems, the tool length measurement of a small-diameter tool mounted on the spindle after the tool replacement is performed by using, for example, the contact-type detector described in the above-mentioned "first prior art". It is most desirable to do this. By the way, in recent years, the vibration generating element at the time of moving the feed shaft of the machine tool has increased with the speeding up of the processing, and the contact type detector which is not affected by such vibration, that is, the contact pressure is high (100 to 100).
A detector having a probe is used for measuring the tool length. Further, at the time of tool length measurement, the speed of approaching the tool to the contact element of the contact type detector is increased to shorten the tool length measurement time as much as possible, and as a result, the machining time is shortened. .

However, when measuring the tool length of a small-diameter tool mounted on the spindle after the tool change using a contact-type detector, the contact pressure of the detector, the approach speed of the tool to the measuring element, etc. May cause breakage or breakage of the tool edge when contacting the probe.
Therefore, in order to automatically measure the tool length of a small-diameter tool mounted on the spindle using a contact-type detector, the contact pressure of the measuring element of the contact-type detector must be reduced in advance (20 to 2).
(Approximately 5 g) and the approach speed of the tool to the probe needs to be extremely low. In this case, the tool length measurement time is unnecessarily lengthened, and as a result, the machining time is extended.

An object of the present invention is to solve the above-mentioned problems inherent in the conventional method and apparatus for measuring a tool length, and to measure the tool length of a small-diameter tool on a machine tool in a short time and with high accuracy. An object of the present invention is to provide a method and an apparatus for measuring a tool length of a machine tool which can be performed.

[0012]

In order to achieve the above-mentioned object, an optical tool tip position detecting means and a contact type tool tip position detecting means are provided on a machine tool. The tool is moved at a relatively high feed rate toward the detection means to detect the tip position, and then, from a predetermined position set in advance, the tool is moved at a considerably low feed rate,
The tool is moved toward the contact-type tool tip position detecting means to detect the tip position, and the tool length of the tool is calculated from the tool tip position detected by the contact-type tool tip position detecting means and the reference position of the main shaft. It is something to do. For details,
Each component is provided as described below. (1) In a machine tool for processing a workpiece by relatively moving a tool and a tool mounted on a spindle, an optical tool tip position detecting means and a contact type tool tip are provided at predetermined positions relatively movable with respect to the tool. A position detecting means for moving the tool toward a measurement area of the optical tool tip position detecting means at a first feed speed to detect the tool tip position, and the contact type tool tip position detecting means; The tool is guided to a position separated by a predetermined distance from the measuring element, and the tool is directed from the predetermined position to the measuring element of the contact-type tool tip position detecting means at a second feeding speed smaller than the first feeding speed. The tool tip position of the tool is detected from the tip position of the tool detected by the contact-type tool tip position detecting means and a preset reference position of the spindle. Is a tool length measurement method for machine tools.

(2) In a machine tool for processing a workpiece by relatively moving a tool mounted on a main spindle and a workpiece in response to a feed axis movement command from a numerical control unit, the workpiece is moved to a predetermined position relative to the tool. The provided optical tool tip position detecting means, the contact type tool tip position detecting means having a tracing stylus provided at a predetermined position relatively movable with respect to the tool, and the tool at a first feed speed. While moving toward the measurement area of the optical tool tip position detecting means to detect the tip position of the tool, guiding to a position separated by a predetermined distance from the measuring element of the contact type tool tip position detecting means, A tool is moved from the predetermined position to the contact point of the contact-type tool tip position detecting means at a second feed rate smaller than the first feed rate, and measurement is performed to detect the tip position of the tool. Measurement control means for controlling operation, tool length calculation means for calculating the tool length of the tool from the tip position of the tool detected by the contact-type tool tip position detection means and a preset reference position of the spindle, A tool length measuring device for a machine tool comprising:

(3) The machine tool according to the above (2), wherein the measuring element of the contact-type tool tip position detecting means is disposed substantially below the measurement area of the optical tool tip position detecting means. Tool length measuring device.

[0015]

The operation of the present invention will be briefly described below. By axially feeding the tool after the tool change at the first feed speed, the tool enters the measurement area of the optical non-contact type position detecting means to quickly detect the tip position of the tool, and the tool has a small contact pressure. The guide is guided at the first feed speed to a position in front of the contact point of the contact type position detecting means and close to the contact point. Simultaneously, the tool is moved to a position close to the contact point of the contact type position detecting means before the contact point, and at the same time, the feed speed of the tool is reduced to a second feed speed which is extremely slower than the first speed.

In order to avoid the influence of vibration generated due to the movement of the tool, the detection signal of the contact-type position detecting means is not output until the tip of the tool passes through the above-mentioned location close to the measuring element of the contact-type position detecting means. Enable (start). The tool tip is made to gradually enter the measuring element at the second feed speed from the point close to the contact-type position detecting means, and by adopting the contact-type position detecting means with extremely small contact pressure, When the tip of the cutting edge of the tool comes into contact with the probe, the chip is prevented from being broken or broken.

When a signal indicating that the tip of the tool has contacted the tracing stylus of the contact type position detecting means is input to the feed axis position detecting means, the axis of the tool is stopped, and the signal from the feed axis position detecting means, The tool length is calculated on the machine by the tool length calculation means based on the tool attachment reference position stored in advance. As described above, based on the method and apparatus described above, conventionally, the measurement of the tool length of a small-diameter tool, which is unfamiliar or impossible with the automatic measurement by the contact-type position detection means, is performed without causing any chipping or breakage of the tool edge. , It is possible to measure with high accuracy in almost the same time as the measurement of the normal tool length, including continuous machining, including tool replacement with the micro-diameter tool
High-precision processing without any step on the processing surface has been enabled.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. Some of the constituent elements of the present invention may be appropriately changed within the technical level of the industry at the time of filing the present invention. Therefore, it is not allowed to reduce the scope of the invention based on only the present embodiment. FIG. 1 is a side view and a configuration block diagram of a main part of an embodiment of a tool length measuring device for a machine tool that implements a tool length measuring method according to the present invention. FIG. It is a principal part front view of a tool length measuring device. FIG. 3 is a plan view of an optical non-contact position detecting device which is one of the components of the device.

Firstly, with reference to FIGS. 1 and 2, illustrating a major part of the NC machine tool having a tool length measuring device. In the figure, N
On a main body (not shown) of the C machine tool, a spindle 3 on which a tool 1 is mounted is rotatably supported on a spindle head 5, and an NC device 68.
By driving the X-axis feed remotor 7, the Y-axis feed remotor 9, the Z-axis feed remotor 11, and the spindle rotation motor (not shown) based on the command from the numerical controller 69, the spindle head 5 and the work ( (Not shown) relative to the table 13 on which X, Y, and Z axes are orthogonally moved in three directions, and the spindle 3 is rotated in the spindle head 5. A collet chuck 15 for holding the tool 1 is screwed to a lower part of a draw bar (not shown) provided in the main spindle 3, and the draw bar is assembled so as to be movable in the main spindle 3 together with the collet chuck 15 in the vertical direction. .

In FIG . 2, a guide 21 is provided on a bracket 19 attached to a side surface of the table 13, and a magazine base 25 is set up on a carrier 23 which is guided by the guide 21 so as to reciprocate in a direction parallel to the X axis. The tool magazine 17 for storing the tool 1 is provided with a magazine base 25.
Fixed on top. The tool magazine 17 is a plate material made of an elastic material such as a resin. The tool magazine 17 includes two upper and lower layers in which a groove 17b is formed in an intermediate portion of the plate thickness, and eight tool pots 17a for storing the tool 1 are formed. An elastic ring 27 is fitted to each tool 1, and the elastic ring 27 is
When the tool 1 is stored in the tool pot 17a of the tool magazine 17, the tool 1 is fitted into the groove portion 17b, and the upper and lower portions thereof are sandwiched and serve as a rough reference in the axial direction, and are gripped by the tool pot 17a.

[0021] plate 29 attached to the left side (see FIG. 2) of the carrier 23, one end of a piston rod 33 of the cylinder 31 provided on the bracket 19 is fixed, the rod 33 by supplying pressurized air to the cylinder 31 The carrier 23 is moved along the guide 21 in a direction parallel to the X-axis. As a result, the tool magazine 17 fixed on the magazine base 25 erected on the carrier 23 is replaced with a tool changer. The work can be reciprocated between a possible forward position (see FIG. 2) and a retracted position outside the processing area of the work. A pulley 35 is provided on the right side of the plate 29.
A pulley bracket 37 for rotatably supporting the pulley 35 is attached, and a pinion 39 fixed coaxially with the pulley 35 is
It is in mesh with the rack 41 attached to the guide 21.
The plate 29 is provided with a cover 43 for preventing chips and cutting fluid from adhering to the periphery of the tool magazine 17 during machining. The cover 43 is coaxially provided with a magazine cover 47 cooperating with a pulley 45. And the pulley 3
A belt 49 is stretched between the belts 5 and 45.

[0022] Usually, the tool magazine 17 is located in the machining area outside a is the retracted position of the workpiece, when the command from the numerical control unit 69 of the NC apparatus 68 of tool change is sent, the tool magazine to the machine control device 71 When the movement command is sent, the cylinder 31 is operated to retract the piston rod 33, the plate 29 is moved rightward, and the tool magazine 17 is advanced to the tool changing position. At the same time, the pinion 39 meshing with the rack 41 attached to the guide 21 and the pulley 35 fixed to the pinion 39 rotate counterclockwise, rotate the pulley 45 counterclockwise via the belt 49, and open. In this state, the tool magazine 17
Automatic tool change or tool magazine 17 by relative movement in the X, Y, and Z axis directions between the machine tool and the spindle 3 of the NC machine tool.
It is possible to manually replace the tool 1 stored in the device.

[0023] That is, when the tool exchange, when the tool 1 which play attached to the spindle 3 is housed in the tool pot 17a of the tool magazine 17, to protrude the collet chuck 15 from the main spindle 3 tip by extruding a drawbar downwards, The tool 1 is unclamped by releasing the collet chuck 15 from the tapered hole at the tip of the spindle. Tool magazine 1
When the tool 1 stored in the tool pot 17a is mounted on the spindle 3, the draw bar is pulled up to fit the tapered portion of the collet chuck 15 with the tapered hole at the tip of the spindle 3 so that the collet chuck 15 has a gripping force. And clamp the tool 1.

[0024] predetermined position on the table 13 does not interfere with the processing is provided with a line sensor (non-contact type detector of the optical type) 51 that detects the position of the tip of the tool 1. Here, the line sensor 51 is not limited to the position on the table 13 and may be provided anywhere as long as the main shaft 3, that is, a position relatively movable with respect to the tool 1. As shown in FIG. 3A, the line sensor 51 has a built-in lens for converting light from a light source such as a light-emitting diode into a parallel light beam 53 in a sensor base 51a mounted on the table 13. A light receiving section 51c in which a plurality of light receiving elements 55 such as charge-coupled devices (CCD) that receive the light beam 53 emitted from the light emitting section 51b are arranged at predetermined intervals (for example, several μm intervals); Are provided, and the light projecting unit 51b and the light receiving unit 51c are provided.
Are arranged so as to face each other. When the tool length is measured, the light receiving element of the light receiving unit 51c indicates that the tool 1 has reached the measurement area between the light emitting unit 51b and the light receiving unit 51c of the line sensor 51 and has blocked the light beam 53 emitted from the light emitting unit 51b. It is detected at 55 and converted to an electrical signal.

Although not shown, the sensor base 5
A contact plate for detecting contact with the tool 1 may be provided at the entrance and the bottom of the measurement area 1a in case the line sensor 51 fails or malfunctions. The contact plate at the bottom is provided with a line sensor 5 from the tool 1 when the tool length is measured.
In addition to preventing chips and cutting fluid scattered in the measurement area 1 from contaminating the light projecting unit 51b and the light receiving unit 51c,
A plurality of nozzles for jetting the pressurized air upward toward the measurement region may be provided so as to also have the effect of preventing fogging of the light receiving portion 1c and the light receiving portion 51c. If the pressurized air is also jetted toward the tool 1, it is possible to blow chips, cutting fluid, and the like attached to the cutting edge or the like of the tool 1 out of the measurement area when measuring the tool length.

The sensor cover 57 provided so as to surround the line sensor 51 prevents chips and cutting fluid scattered during machining from adhering to the periphery of the line sensor 51. Pressurized air is supplied to (not shown) to open, and the measurement area of the line sensor 51 is opened to the tool 1. Referring again to FIG.
The measurement area of the line sensor 51 has a measurement area at a lower position along the axis feed direction (Z-axis direction) of the spindle 3 and a tool tip at a predetermined position on the table 13 which does not hinder processing. A contact sensor 63 for position detection is provided. Similarly to the line sensor 51, the contact sensor 63 is not limited to being provided on the table 13, but may be provided anywhere as long as it can move relative to the tool 1.

As described above, conventionally, for the purpose of speeding up machining and shortening the measuring time, the measuring approach speed to the contact type sensor for measuring the tool length is increased, and the contact pressure of the measuring element is accordingly reduced. About 100-150g,
It is general that the vibration generated based on the axial feed does not affect the measurement accuracy. However, in the contact sensor 63 of the present embodiment, the contact pressure of the probe 65 is reduced to about 20 to 25 g. It is designed so that the edge of the cutting edge does not break or break when the tip of the tool contacts. Further, the feed speed of the tool 1 entering the measurement area is reduced so that the tip of the tool gently hits the tracing stylus 65 when measuring the tool length. The contact sensor 63 is also provided with a sensor cover 67 so as to surround the sensor 63 to prevent chips and cutting fluid scattered during machining from adhering to the periphery of the contact sensor 63. When the tool length is measured, the sensor cover 67 is also opened by supplying air to a cylinder (not shown) to open the measurement area of the contact sensor 63.

The machine tool control means is constituted by a NC device 68 and the machine control device 71. The numerical control unit 69 in the NC device 68 reads and decodes an NC program consisting of a machining program and a tool length measurement program to perform linear interpolation or circular interpolation, and transmits a movement command through the servo unit to the X-axis feed remotor 7, It sends the rotation command to the Y-axis feed remotor 9 and the Z-axis feed remotor 11 to control the drive of each axis feed remotor, and sends a rotation command of the spindle 3 to the spindle rotation motor. Further, the machining program of the NC program includes a tool exchange command and the like, and when a tool exchange command is transmitted in the machining process, the machining is temporarily stopped, the tool magazine 1 is stopped.
7 are sequentially sent to the machine control device 71 in accordance with a program, for example, by changing the tool 1 by moving the main shaft 3 in the X, Y, and Z axes.

The machine controller 71 comprises a measurement controller 73, a tool length calculator 75, a data storage 77, and a feed axis position detector 79. NC in the measurement control unit 73
A tool length measurement program of the program is stored, and a tool movement command to the measurement area of the line sensor 51 or the contact type sensor 63, a tool approach speed (first feed speed) command to the line sensor 51, a probe of the contact type sensor 63 65
To a tool approach speed (second feed speed) command, a position (a feed axis position at which the tool approach speed is reduced from the first feed speed to the second feed speed) at a predetermined distance from the tracing stylus 65 of the contact sensor 63 Tool movement command, etc. are included.

The data storage unit stores the position of the feed axis (calibration data) as a reference for calculating the tool length.
It is obtained and stored in advance before processing.
The calibration data includes the position of the feed shaft when the leading end of the main shaft 1 detects light blocking in the line sensor 51 and the position of the feed shaft when the leading end of the main shaft 1 detects contact with the measuring element 65 of the contact sensor 63. Position. When the calibration data is obtained, when the tip of the spindle 1 approaches each of the sensors 51 and 63, it is assumed that interference between the spindle 1 and each of the sensor bodies 51 and 63 occurs depending on the outer diameter of the spindle 1. Is done. Therefore, a tool having a known tool length is mounted on the spindle 1, and the tool is attached to each sensor 51,
The position of the feed shaft at the time of detecting the light shielding or contact at 63 is detected, and the tip of the main shaft 1 detects the light shielding or contact at each of the sensors 51 and 63 from the detected position and the known tool length. The position of the feed axis is calculated backward.

In the feed axis position detecting section 79, the NC device 68
Of the rotary encoders 8, 1 in response to the movement command sent from the numerical controller 69 to the respective axis feed motors 7, 9, 11.
The position of each feed axis of the X, Y, and Z axes is read every moment via 0, 12 or a linear scale, and when a tool length is measured, a light shielding or contact signal from each sensor 51, 63 at the tip of the tool 1 is received. Thus, the position of each feed axis of the X, Y, and Z axes at that time can be detected. Tool length calculator 75
Then, at the time of measuring the tool length, each sensor 51,
The position data of the feed axes of the X, Y, and Z axes in the feed axis position detecting section 79 when the light shielding or the contact by 63 is detected, the reference position data of the tip of the main shaft 1 stored in the data storage section 77, and The tool length is calculated from. Further, if necessary, a tool offset amount, which is a displacement amount of the tool length, is calculated and transmitted to the numerical control unit 69 of the NC device 68 via the measurement control unit 73.

[0032] (Embodiment 1) or more, based on the tool length measuring device mentioned machine tool, illustrating the tool length measuring method of this embodiment. (1) The elastic ring 27 is fitted to the tool 1 including a plurality of micro-diameter tools used for machining a desired shape, and is stored in the tool pot 17a of the tool magazine 17. When another tool 1 is mounted on the spindle 3, an empty tool pot 17a for returning and exchanging the tool 1 is placed in the tool magazine 1
7 (see FIG. 1). (2) When a tool change command is sent from the numerical controller 69 of the NC device 68, a tool magazine movement command is sent to the machine control device 71, and pressurized air is supplied to the cylinder 31 (see FIG. 2). The magazine 17 advances to a position where the tool can be changed, and the magazine cover 47 is opened. Thereafter, automatic tool change is performed between the tool magazine 17 and the spindle 3 by relative movement in the X, Y, and Z axis directions. Each time, as described above, the collet chuck 15 of the spindle 3 is used.
Is opened and closed to open and mount the tool 1.

[0033] (3) When the tool change is completed, again, pressurized air is supplied to the cylinder 31, the retract the tool magazine 17 to the former position, by rotating the magazine cover 47, covering the tool magazine 17. (4) After the tool change, the measurement control unit 7 of the machine control device 71
The tool 1 is positioned on the measurement area of the line sensor 51 on the basis of a command from the tool length measurement program stored in 3. (5) Next, the line sensor 51 and the contact sensor 63
The sensor covers 57 and 67 are opened, and a light beam 53 is emitted from the light projecting portion 51b of the line sensor 51 to the light receiving portion 51c. At this time, the contact sensor 63 has not been activated yet.

[0034] (6) the tool 1 toward the measuring area of the line sensor 51 is moved in the Z axis direction, for example, 2000 mm / min about feed speed (first feed speed). (7) The output obtained by blocking the light beam 53 toward the light receiving portion 51 c of the line sensor 51 by the tip of the tool 1 is output from the NC device 6.
The movement of the tool 1 in the Z-axis direction is temporarily stopped or decelerated. At the same time, the feed axis position detector 79 of the machine controller 71 receives the light-shielded output of the line sensor 51 by the tip of the tool 1 and detects the position of the feed axis (Z axis) at that moment. Thus, the tip position of the tool 1 mounted on the spindle 3 can be obtained. (8) Then, the tool 1 is moved to the contact point 65 of the contact sensor 63.
The tip of the tool 1 is moved up and the contact type sensor 6
The tool 1 is again moved in the Z-axis direction at the first feed speed until the upper position of the tracing stylus 65, for example, about 50 μm, is reached. For example, by slowing down to a very low feed rate (second feed rate) of about 0.3 mm / min,
The contact sensor 63 is moved toward the probe 65. Here, at the same time when the feed speed of the tool 1 is reduced to the second feed speed, the contact type sensor 63 in which the contact pressure of the tracing stylus 65 is about 20 to 25 g is activated (the detection output from the contact type sensor 63 is enabled). In this way, the vibration generated by the shaft feed is not affected by the detection accuracy of the contact sensor 63.

[0035] (9) output in contact with the measuring element 65 of the contact sensor 63 by the tip of the tool 1, are sent to the numerical control unit 69 of the NC device 68 to stop the movement in the Z-axis direction of the tool 1 . At the same time, the feed axis position detector 79 of the machine control device 71 detects the contact type sensor 63 by the tip of the tool 1.
, The position of the feed axis (Z-axis) at that moment is detected and sent to the tool length calculating section 75. Therefore, the tool 1 is axially fed at a considerably low feed speed to contact the measuring element 65 with a very small contact pressure of the contact sensor 63, so that the tool edge is chipped or broken even with a small diameter tool. There is no fear. (10) The position of the feed axis (Z axis) at the moment when the tip of the tool 1 comes into contact with the tracing stylus 65 of the contact type sensor 63, which is detected and sent out by the feed axis position detector 79 of the machine control device 71,
Upon receiving the feed axis reference position data stored in the data storage unit 77, that is, the reference position data of the tip end of the spindle 1, the tool length calculation unit 75 calculates the tool length of the tool 1.

[0036] (Embodiment 2) FIG. 3 a laser sensor 59, as shown in (b), the tool length measuring method described in the <Embodiment 1>, the line sensor of the components of the apparatus 5
It is arranged and configured on the table 13 instead of 1. As with the line sensor 51, the laser sensor 59 only needs to be located at a position relatively movable with respect to the tool 1. Since the light beam 53 of the line sensor 51 has a width, the most protruding position of the tip of the tool 1 can be detected without rotating the tool 1. The light projecting portion 59b of the laser sensor 59 includes:
Light receiving unit 5 facing one beam (laser) beam 61
When the tool length is measured, the measurement is performed between the light emitting unit 59b and the light receiving unit 59c of the laser sensor 59 while rotating the tool 1 (normally, the number of rotations in the processing state). It is said that unless it is made to enter the area, the most protruding position of the tip of the tool 1 cannot be detected, and accurate tool length measurement cannot be performed.

[0037] Incidentally, 51a is a sensor base of the laser sensor 59. Other configurations, for example, sensor attachment devices such as a sensor cover and a contact plate may be understood to be the same as those of the line sensor 51. In the present embodiment, the detection of the tip position of the tool 1 is performed by the contact type sensor 6.
3, the rotation of the main shaft 3 is stopped. Other tool tip position measurement means, configurations, and operations are as follows:
As described in the first embodiment.

[0038] (Embodiment 3) tool length measuring method in the two embodiments described above, at least, a combination of a non-contact type optical sensor and contact sensor 63 in the apparatus, conventionally, only the contact sensor 63 It has become possible to measure the tool length of a small-diameter tool, which has been considered to be difficult, with high accuracy in a short time without causing breakage or breakage of the tool edge. In this case, in view of the tool length measuring method and the configuration of the device, the optical non-contact type sensor and the contact type sensor 6 may be used.
3 are provided along the axis feed (Z-axis) direction of the tool 1, the tool 1 can be moved at a stroke from the measurement area of the non-contact type sensor to the measuring element 65 of the contact type sensor 63. It is clear that the operation for moving horizontally in the Y-axis direction and the time can be saved, and the measurement time can be shortened.

FIG . 4 shows another embodiment in which the elements of the optical non-contact type sensor 51 and the contact type sensor 63 of (Embodiment 1) are rearranged in the vertical direction in accordance with the above-mentioned purpose. FIG. In the drawings, the reference numerals assigned to the sensor constituent members shown in FIGS. 1, 2 and 3 are the same as those described with reference to FIGS.
In the present embodiment, the measurement region of the optical non-contact sensor 51 and the tracing stylus 65 of the contact sensor 63 overlap vertically, and the tip of the tool 1 is moved only by moving the tool 1 in the Z-axis direction. Position detection is possible, so that it is not necessary to move the horizontal plane of the tool 1 in the X and Y axis directions between the measurement area of the optical non-contact sensor 51 and the tracing stylus 65 of the contact sensor 63. .

The optical non-contact sensor may be a line sensor 51 or a laser sensor 59. The rotation of the spindle 3 corresponds to the type of sensor and is programmed as described above. For other configurations and operations, refer to the description in (Embodiment 1).
Although the embodiment of the present invention has been described based on the form of the vertical machining center in which the main shaft rotates around the vertical axis, it goes without saying that the present invention can also be applied to a horizontal machining center in which the main shaft rotates around a horizontal axis.

[0041]

According to the present invention, by automatically providing an optical non-contact type sensor and a contact type sensor having a small contact pressure, the tool length of a small-diameter tool, which has been considered impossible or difficult in the past, can be automatically controlled. Measurement is possible,
Even if the micro-diameter tools are sequentially replaced, the tool length can be accurately measured after the replacement, and high-precision machining can be continuously performed without generating a step on the workpiece machining surface. The tip position of the tool is detected by an optical non-contact type sensor, and it is quickly guided to the contact point of the contact type sensor with a small contact pressure. There is no breakage or breakage of the cutting edge, and the tool length can be accurately and efficiently measured in a short time.
For example, conventional methods and devices cannot be expected.
Functions and effects can be obtained.

Claims (3)

[Claims] 1. A machine tool for processing a work by relatively moving a tool and a work mounted on a main spindle, wherein the optical tool tip position detection means and a contact type are provided at a predetermined position relatively movable with respect to the tool. Tool tip position detecting means is provided, and the tool is moved at a first feed speed toward a measurement area of the optical tool tip position detecting means to detect the tool tip position, and the contact type tool tip position is provided. Guiding the tool to a position separated by a predetermined distance from the measuring element of the detecting means, the measuring element of the contact-type tool tip position detecting means from the predetermined position at a second feeding speed smaller than the first feeding speed. , The tip position of the tool is detected, and the tool position is determined from the tip position of the tool detected by the contact-type tool tip position detecting means and a preset reference position of the spindle. Of calculating a tool length, machine tool length measuring method, wherein a. 2. A machine tool for processing a workpiece by relatively moving a tool mounted on a spindle and a workpiece in response to a feed axis movement command from a numerical controller, wherein the workpiece is provided at a predetermined position capable of relatively moving with the tool. Optical tool tip position detecting means provided; contact-type tool tip position detecting means having a tracing stylus provided at a predetermined position capable of relatively moving with the tool; and the optical tool at a first feed speed. The tool is moved toward the measurement area of the tool tip position detecting means of the type to detect the tip position of the tool, and is guided to a position separated by a predetermined distance from the measuring element of the contact type tool tip position detecting means, At a second feed speed lower than the first feed speed from the predetermined position to the contact point of the contact-type tool tip position detecting means, so that the measuring operation is performed to detect the tip position of the tool. Measurement control means for controlling, tool length calculation means for calculating the tool length of the tool from the tool tip position detected by the contact-type tool tip position detection means and a preset reference position of the spindle, A tool length measuring device for a machine tool, comprising: 3. A tool length measuring device for a machine tool according to claim 2, wherein a measuring element of said contact type tool tip position detecting means is arranged at a position substantially below a measuring area of said optical tool tip position detecting means. .