JPH0478428B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a contact detection device that performs centering and dimension measurement of a workpiece using a contact detection tool attached to the main shaft of a machine tool such as a machining center. It is.

(Prior art and its problems) A system for centering and measuring the dimensions of a workpiece in a machining center is equipped with a movable contact and an internal switch that is operated by the movement of the movable contactor in contact with the workpiece. Using a touch sensor, a touch signal is extracted via an internal switch when the movable contact element contacts the workpiece, and this is
In addition to the touch sensor system with an internal switch that provides feedback to the NC device, an energized touch probe system is known, which is disclosed in Japanese Patent Application Laid-Open No. 61-214953.

In this current-carrying touch probe method, as shown in Fig.
When the touch probe 1 and the conductive workpiece 3 come into contact with each other, a closed circuit 5 is formed that passes through the main shaft 2 → touch probe 1 → workpiece 3 → machine tool body 4 → main shaft 2 in series. This closed circuit 5 is electromagnetically detected by a sensor 6 disposed around the main shaft 2 to output a touch signal 7, which is then fed back to the NC device 8. 9 is a sensor drive and touch signal output circuit.

Compared to the former touch sensor method with an internal switch, the latter energized touch probe method allows the cutting tool and workpiece 3 to be connected even when an energized cutting tool is used instead of the touch probe 1.
The sensor 6 can similarly detect the energization state due to contact with the cutting tool, so for example, by monitoring the energization state during machining, it is possible to automatically detect breakage of the cutting tool or to shorten the air cutting time. This method has advantages such as being able to rapidly feed the tool until the workpiece and the tool come into contact, and then automatically switch to normal cutting feed at the moment the workpiece and the tool come into contact, so it is useful.

However, in the current-carrying touch probe method, the workpiece 3 is limited to conductive metal, and not only can it not be used with resin or ceramic workpieces, but even if the workpiece is metal, it cannot be used. If water-soluble cutting oil is attached to the measurement surface, a touch signal will be output due to the conductivity of water even though there is no contact yet, and if oil-based cutting oil is attached to the measurement surface, the insulation of the oil film will be output. This causes a delay in the output timing of the touch signal, and there is a problem in that high precision measurement cannot be performed in any case.

In order to solve this difficulty, for example,
A wireless energizing type touch probe disclosed in Japanese Patent No. 96749 has been proposed, which can detect contact without being affected by the material of the workpiece or cutting oil, but this structure requires a type of differential voltage. Since the mechanism is designed to detect changes in differential voltage, an induced current always flows through the coil on the contact signal extraction side even when the movable contact and the workpiece are not in contact with each other, and the predetermined voltage is maintained. The coil simply detects the voltage change.

Because of this, contact and non-contact cannot be detected as on or off.

Since it cannot be detected whether it is on or off, it has poor noise resistance and is not suitable for practical use.

On the other hand, a touch probe has been proposed in Japanese Patent Application Laid-Open No. 55-36798, which solves the above-mentioned problems and detects contact and non-contact between a movable contactor and a workpiece in an on/off manner.

However, with this conventional technology, the closed circuit is in communication when the movable contact and the workpiece are not in contact with each other, so if the contact detection tool has a built-in power source, for example, the power is constantly consumed. However, there is a fatal flaw in that it consumes power in a short period of time.

(Means for Solving the Problems) In view of the above-mentioned conventional problems, the present invention utilizes the current conductivity detection system in the current-carrying touch probe method, which has high utility value, and also detects the material of the workpiece and Highly accurate contact detection is possible without being affected by cutting oil, and contact and non-contact can be turned on and off.
We propose a contact detection device that performs off-state detection and does not consume power at all times, that is, when there is no contact.The feature is that it is operated by the movement caused by the contact between the movable contact and the workpiece. In addition, when the movable contact comes into contact with the workpiece and the movable contact is displaced, the normally closed switch becomes open and is cut off, but the electric circuit opening/closing means is built in, which has a switching means that connects the electric circuit, that is, makes it energized. A contact detection tool is attached to the main shaft of the machine tool, and the contact detection tool is further provided with a terminal that can be freely connected to and separated from the terminal on the machine tool main body side, and these terminals, the main shaft, and the electric circuit opening/closing means are connected in series. Necessary wiring for configuring the circuit is provided, and a sensor is provided around the main shaft to electromagnetically detect the opening/closing of the closed circuit accompanying the opening/closing operation of the electric circuit opening/closing means.

(Operation of the invention) When the main shaft to which the contact detection tool is attached is moved to bring the movable contact of the contact detection tool into contact with the workpiece, the movable contact moves due to reaction force and the internal circuit opening/closing means is moved. The circuit opening/closing status is reversed.
The movement of the movable contact due to contact with the workpiece, and furthermore, the opening/closing operation of the electric circuit opening/closing means due to the contact between the movable contact and the workpiece, is affected by the material of the workpiece and the cutting oil adhering to the measurement surface of the workpiece. It is done without

On the other hand, when the electric circuit opening/closing means is open, a closed circuit in which the terminal on the machine tool main body side, the terminal on the contact detection tool side that is in contact with this, the main shaft, and the electric circuit opening/closing means are connected in series. is in communication (energized state), and when the circuit opening/closing means is open, the closed circuit is interrupted (non-energized state). That is, this electric circuit opening/closing means has a switching means that connects the electric circuit (closed circuit) (that is, becomes energized) when the movable contact contacts the work and the movable contact is displaced. In a normal state in which the movable contact is not in contact with the workpiece, the normally closed switch itself is in a closed (on) state, but the circuit opening/closing means is in a closed state, and the closed circuit is interrupted and no electricity is applied. Since the sensor electromagnetically detects the switching of the open/close state of this closed circuit, the sensor detects that the movable contact of the contact detection tool has come into contact with the workpiece and the internal electric circuit opening/closing means has operated. And you can get the touch signal. As in the conventional case, this touch signal can be fed back to the NC device and used for the desired measurement action.

Furthermore, when the movable contact comes into contact with the work, the normally closed switch is opened and turned off (off), so naturally no voltage is applied to the normally closed switch during this opening operation. No damage to normally closed switches.

The sensor that electromagnetically detects the opening and closing of the closed circuit is composed of an excitation coil and a detection coil, as is conventionally known from, for example, Japanese Patent Laid-Open No. 61-214953, and when the closed circuit is closed, An induced current flows through the closed circuit due to the electromagnetic induction action of the excitation coil, and a detection signal is output when the detection coil detects this induced current. Therefore, even during normal machining operation when a conductive cutting tool is set on the spindle instead of the contact detection tool, while the tool is in contact with the conductive workpiece, the cutting from the spindle will continue. A closed circuit is established in which oil is passed through the tool, workpiece, machine tool body, and spindle in series.
This closed circuit can be detected by the sensor on and off. That is, the sensor can also be used in a current conductivity detection system in a conventional current conduction type touch probe system.

(Example) Examples of the present invention will be described below based on the attached FIGS. 2 to 6.

In FIG. 2, reference numeral 10 denotes a contact detection tool attached to the main shaft 2, which includes a tapered shank part 11 that is fitted and fixed to the main shaft 2, a manipulator grip part 12, a movable contact 13, Movable terminal 1
4, and a built-in electric circuit opening/closing means 15. Reference numeral 16 denotes a fixed terminal on the side of the machine tool main body 4, which connects the contact detection tool 10 to the main shaft 2 at a predetermined phase.
It is attached to the headstock 4a that supports the spindle 2 via a bracket 17 made of an electrically insulating material so that the movable terminal 14 of the contact detection tool 10 comes into contact with the machine tool body 4 when the contact detection tool 10 is fitted and fixed. They are connected by wiring 18. The sensor 6 is composed of an excitation coil 19 and a detection coil 20 which are externally fitted and fixed to the headstock 4a.

Incidentally, the fixed terminal 16 may be supported by the machine tool main body 4 via a conductive bracket instead of the headstock 4a, and the wiring 18 may be omitted. Furthermore, when the movable terminal 14 is configured to directly contact the metal surface of the machine tool body 4, the metal surface of the machine tool body 4 also serves as a fixed terminal.
The fixed terminal 16 and bracket 17 can be omitted.

The structure of the contact detection tool 10 is shown in FIGS. 3 and 4.
To explain in detail based on the figure, the contact detection tool 10
A flange portion 23 facing a receiving seat 22 that is fitted and fixed inside the main body cap portion 21 is concentrically connected to the inner end of the movable contact 13 passing through the main body cap portion 21. Fixed contacts 25 to 27 are fixed to three locations around the surface of the receiving seat 22 via electrical insulating materials 24, respectively, and each of the fixed contacts 2 is fixed to the flange portion 23 of the movable contact 13.
Movable contacts 28 to 30, which can be freely moved into and out of contact with contacts 5 to 27, are fixed to each of the contacts 5 to 27 via electrical insulating material 31, respectively. Reference numeral 32 denotes a rotation stopper pin, one end of which is fixed to the main body intermediate member 34 of the contact detection tool 10 while passing through a radially elongated hole 33 formed in the flange portion 23 of the movable contactor 13. .

The contact detection tool 10 is attached to the main body intermediate member 34.
A movable body 35 that can freely slide in the axial direction is supported concentrically via a slide bearing 36.
The movable body 35 is pressed toward the movable contact 13 by a coil spring 37, and is connected to the hemispherical recess formed at its tip and the center of the inner end of the movable contact 13 (the center of the surface of the flange portion 23). A sphere 38 is interposed between the hemispherical recess and the formed hemispherical recess. Therefore, the movable contact 13 is connected to the spherical body 38.
and the coil spring 3 via the movable body 35.
7 and the movable contacts 28 to 30 around the flange portion 23 come into contact with the fixed contacts 25 to 27 around the receiving seat 22, resulting in a neutral posture concentric with the axis of the contact detection tool 10. is held in

The movable terminal 14 slides within a certain range in a direction parallel to the axis of the contact detection tool 10 via a sleeve 39 made of an electrically insulating material on a support portion 34a that protrudes laterally from the main body intermediate member 34. The movable contactor 13 is attached to the tip of a slide rod 40 that is held movably, and is supported by a coil spring 41.
It is biased so that it protrudes in the opposite direction to the side where it is located. 42 is a flexible dust cover interposed between the movable contactor 13 and the main body cap portion 21.

As shown in FIGS. 4 and 5, the movable contacts 28 and 29 on the movable contactor 13 side are connected to each other by wiring 43, and the remaining movable contact 30 is connected to the receiving seat 22.
connected by a fixed contact 26 on the side and wiring 44,
Of the remaining fixed contacts 25 and 27, the fixed contact 25 is connected to an appropriate location on the main body (cap part 21, etc.) of the contact detection tool 10 with a wiring 45, and the fixed contact 27 is connected to the movable terminal 14 via a wiring 46 and a slide rod 40.
It is connected to the. This wiring 46 must not obstruct the movement of the slide rod 40. Moreover, the electrical insulating material 24 between the fixed contact 25 and the receiving seat 22 is omitted, and the fixed contact 25 and the receiving seat 2 are
2 can be electrically connected directly to omit the wiring 45.

The electric circuit opening/closing means 15 connects the fixed contacts 25 to
27, movable contacts 28 to 30, and wiring 43, 44
A normally-closed switch 47 consisting of a switch 47 and a normally closed switch 47 consisting of a If any one of the three contact pairs is separated, the wiring 45, 4
6 are separated from each other and the switches are in an open state, and as shown in FIG.
The normally-closed switch 47 is connected to a DC power supply 50 (of course, this may be a power supply obtained by rectifying the current induced by the excitation coil 19), a power switch 51, and a logic NOT circuit element 5.
2, and an a-contact type switching means 54 (also shown in a block diagram in FIG. 5) which is formed by using a switching transistor 53 in combination; 46, and the emitter of the switching transistor 53 is connected to the main body of the contact detection tool 10.

According to the electric circuit opening/closing means 15 having the a-contact type switching means 54, the power switch 51
Even if the movable contact 13 is in the neutral position and the normally closed switch 47 is closed, the output terminal of the logic NOT circuit element 52 is at L level,
Since no base current flows through the switching transistor 53, the collector and emitter of the switching transistor 53 become non-conductive (switch OFF state), and the circuit opening/closing means 15
is in a closed state, and the movable terminal 14 is in a state separated from the main body of the contact detection tool 10, so the closed circuit 48 is cut off (that is, in a non-energized state). When the movable contactor 13 moves and the normally closed switch 47 opens, the output terminal of the logic NOT circuit element 52 becomes H level, and the switching transistor 53 is activated through the circuit element.
A base current flows through the switch, and the collector and emitter of the switching transistor 53 become conductive (switch ON state), and the circuit opening/closing means 1
5 is in an open state, and the movable terminal 14 is electrically connected to the main body of the contact detection tool 10 via the switching transistor 53, so that the closed circuit 48 is in communication (that is, the movable terminal 14 is in an energized state). ). Therefore, in the present invention, the sensor 6 detects the induced current flowing through the closed circuit 47 when the movable contactor 13 moves in contact with the workpiece.

When the movable terminal 14 contacts the fixed terminal 16 and moves backward against the coil spring 41 as shown in FIG. The actuator is kicked by the operation piece 55 attached to the unit.
It can be attached via a suitable bracket 56 to the support portion 34a etc. that supports the slide rod 40 so as to be turned on. Further, the constituent members of the a-contact type switching means 54 are built into the contact detection tool 10 except for the power switch 51.

As shown in FIG.
When the movable terminal 14 is attached in a predetermined phase to the machine tool body 4, the movable terminal 14 is pressed against the fixed terminal 16 on the machine tool main body 4 while being slightly retracted against the biasing force of the coil spring 41. At this time, the machine tool main body 4 and the fixed contact 25 of the normally closed switch 47 are connected to the main shaft 2,
The tapered shank portion 11, the main body of the contact detection tool 10, and the wiring 45 are electrically connected to each other. As a result, as shown in FIG. 2, FIG. 5, and FIG. 6, the main shaft 2 → main body of the contact detection tool 10 → wiring 45 → normally closed switch 47 → switching means
A closed circuit 48 is formed which passes through (logic negation circuit element 52→switching transistor 53)→wiring 46→movable terminal 114→fixed terminal 16→wiring 18→machine tool body 4→spindle 2 in series.

On the other hand, when no external force is applied to the movable contact 13, the movable contact 13 is held in a neutral position by the biasing force of the coil spring 37, as shown in FIG. 25-2
7 and movable contacts 28 to 30 are in contact with each other, so that the normally closed switch 4
7 is in a closed state as shown in FIG. That is, when no external force is applied to the movable contactor 13, the normally closed switch 47 is closed, so the closed circuit is closed by the action of the logic NOT circuit element 52 and the switching transistor 53, which are the switching means 54. 48 is in a blocked state. That is, the circuit opening/closing means 15 is in a non-conducting state (closed state). When the movable contactor 13 comes into contact with the workpiece and is displaced, the normally closed switch 47 becomes open, so the circuit opening/closing means 15 switches to an open state (conducting state), and the closed circuit 48 becomes in a communicating state. In this state, if a high frequency current is supplied to excite the excitation coil 19 of the sensor 6 loosely fitted to the main shaft 2, which is a part of the closed circuit 48, an induced current due to electromagnetic induction will flow in the closed circuit 48. The induced current component flowing in this closed circuit 48 is detected by the detection coil 2 of the sensor 6.
0 can be used for detection. Since this detection operation is the same as that in the conventional system described based on FIG. 1, a detailed explanation will be omitted.

However, as mentioned above, the contact detection tool 10 is attached to the main shaft 2.
As a result of moving the headstock 4a and moving the movable contact 13 closer to the workpiece with the holder attached, when the movable contactor 13 comes into contact with the workpiece, the movable contactor 13 is moved by the reaction force of the coil spring 37. It will move from a neutral position against the biasing force. For example, when the movable contactor 13 moves in a direction perpendicular to its axis and contacts the workpiece, the contact pairs 25, 28, 26, 2 that are in contact with each other
The movable contact 13 swings around any one of 9, 27, and 30 or two adjacent ones as a fulcrum, and the remaining one or two contact pairs are separated to form a normally closed switch 47.
opens. At this time, the center of the inner end of the movable contactor 13 is held at the axial center position of the movable body 35 via the sphere 38. When the movable contact 13 moves in the axial direction and contacts the workpiece, the movable contact 13 moves linearly backward in the axial direction, and the contact pairs 25, 228, 26, which are in contact with each other, 29, 27, 3
0 are simultaneously separated and the normally closed switch 47 is opened.

In any case, when the movable contactor 13 comes into contact with the workpiece and moves against the biasing force of the coil spring 37, the normally closed switch 47 opens. 4
8 are connected, an induced current by the excitation coil 19 of the sensor 6 flows through the closed circuit 48, and a detection signal is output from the detection coil 20.
In this state, it is possible to detect that the movable contactor 13 has contacted the workpiece. When the headstock 4a is moved in the opposite direction to separate the movable contact 13 from the workpiece, the movable contact 13 automatically returns to its original neutral position due to the biasing force of the coil spring 37, and is normally closed. The switch 47 returns from the open state to the closed state, and the closed circuit 48 returns to its original cutoff state (ie, non-conducting state).

(Effects of the Invention) As described above, according to the contact detection device of the present invention,
Rather than detecting the energization state between the movable contact of the contact detection tool and the workpiece due to contact with the workpiece, the contact movement of the movable contactor with respect to the workpiece is detected. Contact between the movable contact and the workpiece can be detected reliably and accurately without being affected by adhering cutting oil.

Moreover, the detection method uses a sensor to electromagnetically detect the on/off state of a closed circuit that includes the main shaft of the machine tool, so a signal with an extremely large rate of change is output when the movable contact is in or out of contact with the workpiece. This has the advantage that not only sensitivity can be increased, but also noise resistance can be significantly improved.

Furthermore, the electric circuit opening/closing means for opening and closing the closed circuit includes a switching means that connects the electric circuit (i.e., makes it energized) when the movable contact contacts the work and the movable contact is displaced. In the normal state where the movable contact is not in contact with the work, it is not energized, and when the contact detection tool has a built-in power supply, it consumes less power and can be used stably over a long period of time.

Also, when the movable contact contacts the workpiece and is displaced, the normally closed switch is opened and shut off, so when this opening operation occurs, a voltage is naturally applied to the normally closed switch. This prevents damage to the normally closed switch and enables stable use over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view illustrating the conventional energized touch probe system, Fig. 2 is a side view illustrating the usage state of the embodiment of the present invention, and Fig. 3 is a schematic side view illustrating the detailed structure of the contact detection tool. FIG. 4 is an exploded perspective view illustrating a movable contact and a normally closed switch, FIG. 5 is an electrical circuit diagram of the main part of an embodiment of the present invention, and FIG. 6 is an embodiment of the present invention. FIG. 2 is an electric circuit diagram for explaining the power switch in detail and a side view showing a power switch attachment part. 2... Spindle, 4... Machine tool body, 4a... Headstock, 6... Sensor, 10... Contact detection tool,
13...Movable contact, 14...Movable terminal, 15...
...Circuit opening/closing means, 16...Fixed terminal, 18, 43
~46... Wiring, 19... Excitation coil, 20...
Detection coil, 25-27...Fixed contact, 28-3
0...Movable contact, 35...Movable body, 37, 41...
... Coil spring, 38 ... Sphere, 47 ... Normally closed switch, 48 ... Closed circuit, 51 ... Power switch, 52 ... Logic negation circuit element, 53 ... Switching transistor, 54 ... Switching means.

Claims (1)

[Claims] 1 It operates due to the movement caused by the contact between the movable contact and the workpiece, and when the movable contactor contacts the workpiece and the movable contactor is displaced, the normally closed switch becomes open and is cut off, but the electrical circuit remains open. That is, a contact detection tool having a built-in electric circuit opening/closing means having a switching means for energizing is attached to the main shaft of the machine tool, and a terminal is provided on this contact detection tool that can be freely connected to and separated from the terminal on the machine tool body side. Necessary wiring is provided to configure a closed circuit in which both terminals, the main shaft, and the electric circuit switching means are connected in series, and the circuit is connected around the main shaft to open and close the closed circuit as the electric circuit switching means opens and closes. A contact detection device equipped with an electromagnetic sensor.