JPH0259921B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to improving the detection accuracy and reliability of a three-dimensional position detection device, particularly a position detection device equipped with a stylus holding mechanism having an electrode contact at one end thereof. Regarding the improvement of

Background technology and its problems As is well known, in machine tools such as milling machines,
There is a growing trend for a processing machine to have a function of measuring three-dimensional dimensions of a workpiece after processing. For this reason, conventionally, position detection devices such as those shown in Figures 1 and 2 have been used to detect the position of the reference plane and end face of the workpiece, and to detect the machining position from the reference plane and end face. .

In FIGS. 1 and 2, reference numeral 11 denotes an electrode contact made of a conductive sphere, which is provided at one end of the filler 12, and its holding mechanism is constructed as follows.

That is, within the housing 1, the filler 12
is fixed to the disc 4, and receiving members 6, 7, and 8 are held and fixed to the disc 4 via the insulating plate 5.

At the bottom of the housing 1, set screws 3 having spherical bodies 2 are arranged at approximately three equal parts. This spherical body is adapted to come into contact with the receiving members 6, 7, and 8, and a pressing force is applied by the spring 10 via the insulating member 9, so that they are pressed into contact with each other.

14 is a lock screw for locking the set screw 3. The position detecting device having the above-mentioned configuration is connected to the machine tool 1 by the shank 13 as shown in FIG.
4, the filler 12 and the workpiece 14 are electrically connected to the detection circuit 16, and the electrode contact 11 is attached to the workpiece 14 placed on the table 15.
When the contact is made, this contact is directly electrically detected by the detection circuit 16, and the position and the like are detected.

However, the conventional position detection method described above has good detection accuracy, but if the workpiece is not conductive or has a non-conductive film formed on its surface due to oxidation etc., detection may be difficult. This has the drawback of causing accidents, especially in the case of automatic machining. In addition, as is clear from Fig. 2, the stylus holding mechanism has a conical shape, a V-groove shape, and a flat shape for the receiving members 6, 7, and 8, and each of them is in contact with each sphere 2, so that it is the only stable one in three dimensions. It is now possible to secure a certain position.

Therefore, there is a large variation in the measured pressure depending on the direction when the electrode contactor makes contact, and the number of parts is also increased.Moreover, the processing of the receiving member is troublesome and requires many man-hours, resulting in high cost.

In addition, for the above-mentioned external switch method that uses a switch function outside the housing, which directly electrically detects the contact of the electrode contactor with the workpiece, for example, Japanese Patent Laid-Open No. 56-8502 discloses As disclosed in , the contact of the electrode contact with the workpiece causes a change in the position of the stylus holding mechanism within the housing, and in response, a switch (internal switch) provided in the mechanism is turned on and off. Some devices employ an external switch method to detect the above-mentioned contact.

According to this method, the position can be detected even if the electrode contact is a non-conductor, but the internal switch is activated only after the electrode contact comes into contact with the workpiece and stress is applied to the stylus. Therefore, the stylus ends up being bent during that time. This causes an error in position detection; for example, when the operating stress acting on the electrode contactor during contact with a workpiece is 50 g, the position detection error becomes about 10 μm.

Moreover, as shown in FIG. 12, the operating stress S and the position detection error E differ depending on the direction.
This is because the stylus holding mechanism has three operating fulcrums.

OBJECTS OF THE INVENTION An object of the present invention is to provide a three-dimensional position detection device that has the advantages of the above-mentioned internal switching method and external switching method, has good detection accuracy, and is highly reliable.

Summary of the Invention In order to achieve the above object, the position detection device of the present invention holds a conductive electrode contactor through a stylus by a holding means in a housing, and the contact between the electrode contactor and the object to be measured causes the contact between the two. The present invention is characterized in that it is configured to generate a signal in response to a change in the conductivity of the holding means or a displacement of the holding means at this time.

The electrode contactor is made of, for example, a conductive sphere, and the holding means is made up of first and second holding members in pressure contact within the housing, the first holding member being in line contact with the concentric spherical surface. A conductive film is formed on one of both holding members, and the other is made of an insulating material, and is configured to detect a signal responsive to contact between the workpiece and the electrode contact from the stylus and/or the conductive film. be done.

Embodiments The present invention will now be described with reference to embodiments shown in the drawings. In FIGS. 4a, b and 5, an electrode contactor 21 is attached to one end of a stylus 22,
a first retaining member within the housing 26, e.g. disc 2;
The other end of the stylus 22 is fixed to 3.
The circumferential portion of the disk 233 is formed to form a rotating curved surface body 24 .

A second holding member 25 is disposed at the bottom of the housing 26, and the rotating curved surface body 24 and the second holding member are pressed together by a spring 28, and the contact surface of the holding member 25 is as shown in the figure. It has a spherical shape concentric with the electrode contactor 21.

Further, the rotating curved surface body 24 has metal films 29a, 29
terminals 29a', 29b', 29c' are arranged on each metal film, and lead wires l ₁ , l ₂ , l ₃ are provided from the respective terminals. It is drawn out and connected to the OR circuit OR as shown in FIG. This OR circuit is further connected to the stylus 22 via the switch SW and the inverter circuit INV.
Lead wire from L ₄ is connected.

Furthermore, a relay plate 27 is provided on the upper part of the housing 26, and a shank 29 is provided on this relay plate 27.
is attached, and as described above, the position detecting device of the present invention described above is connected to the sixth position detecting device via the shank.
As shown in the figure, it is attached to a machine tool 42 or the like.

Now, in the apparatus of the present invention described above, the first holding member 23 is temporarily attached to the contact surface of the second holding member 25 for positioning the electrode contactor 21 as shown in FIG.
are in contact at three points A, B, and C, it is on a spherical surface of radius R with respect to the center Q of the electrode contactor 21.

As mentioned above, the center of the electrode contactor 21 and the center of the contact surface (spherical surface) of the second holding member 25 coincide, so if one point among the three points A, B, and C on the spherical surface is P, then =R, even if the positions of A, B, and C, that is, P change, the position of Q remains unchanged.

Next, if an error of =R+ΔR, ie, ΔR occurs, and P is shifted by Δd, Q will shift to the position of Q', and the error'=ε will be as follows.

ε=ΔdΔR/R Therefore, even if there is an error of Δd in the setting position of the holding member of the electrode contactor, the error of the electrode contactor is reduced to ΔR/R. A rotary curved body 24 of 23 has the axis of the stylus 22 as its central axis, and is pressed into contact with the concentric spherical surface of the second holding member 25 so as to be in line contact with the circular line l, and the periphery of the rotary curved body 24 is surrounded by the housing. 2
Since it is statically fitted with 6, Δd in the stationary state
≒0, and the error ε becomes extremely small.
Further, the electrode contactor can operate smoothly even if force is applied in any three-dimensional direction to the electrode contactor.

The rotating curved surface body 24 is made of an insulating material, for example, and is always in full contact with the second holding member 25 due to the instantaneous mechanical displacement when the electrode contactor 21 contacts the object to be measured (conductor or insulator). Any contact on the metal film is turned off, and position detection is performed.
That is, an internal switch function is provided, but an external switch output is also provided by the lead from the stylus.

FIG. 6 shows an example of a contact position detection circuit used in the present invention, in which lead wires 31, 32 and a workpiece 33 from a connector 30 coupled to the housing 26 and connected to the output of the OR circuit OR are mounted. A lead 36 from a table 35 is connected to the input of an amplifier 37. The output of the amplifier 37 is connected to an excitation winding 38' of a relay 38, and a power source 39 is connected via the relay 38 to an alarm device 40 such as a lamp or a buzzer, and to a counter 41.

Now, when the table 35 of the machine tool or its main shaft 41 is moved vertically and horizontally in the direction of the arrow and the electrode contactor 21 approaches and contacts the end face of the workpiece 33, the input of the amplifier 37 becomes a closed circuit. The output activates the relay 38. The annunciation device 40 is therefore activated and the point of contact is quickly and accurately detected. At the same time, an input is given to the counter 41, so by resetting the counter 41 to zero based on the input and starting counting from this point, it is possible to know the distance traveled by the table or the spindle.

Incidentally, the rotating curved surface body 24 may be a conductor, the second holding member 25 may be an insulator, and conductive films 8a', 8b, and 8c may be provided thereon as shown in FIG.

In addition, as shown in FIG. 9 or 11, the bottom surface of the first holding member 23 is made into a concave spherical surface concentric with the electrode contactor 21, and the second holding member 25 is provided with a rotating curved surface body 24, so that either one of them is conductive. A film may be formed, and the other may be an insulator.

Furthermore, by turning off the switch SW, the external switch function can be disabled. In this way, when cutting fluid etc. are used for machining,
Due to the electrical conductivity caused by this, it is possible to prevent incorrect position detection.

FIG. 13 shows still another embodiment of the present invention, in which the lead wires _l1 to _l3 of the internal switch are connected to a first OR circuit _OR1.
and its output is connected to the second OR circuit _OR2 together with the output of the inverter circuit INV.

Further, the output of the first OR circuit _OR1 is further connected to an AND circuit AND together with the input of the inverter circuit INV, and the output of this AND circuit drives the alarm circuit AL.

According to this embodiment, when the external switch is not operating (when the electrode contactor is not in contact with the workpiece),
When the internal switch operates, this abnormality is detected by the alarm circuit AL and an alarm is generated.

Effects of the Invention As is clear from the above explanation, according to the present invention, an OR is taken between the internal contact switch and the external contact switch, and both holding members of the electrode contact are in line contact. , the contact area is large, and the amount of movement of the stylus is constant in any direction in the horizontal direction. Therefore, since the position of the stylus is mechanically accurate and the electrode contactor is held at a constant position, it can be accurately detected by the output of the external switch. Moreover, even if an accident occurs in which the external switch output cannot be obtained when the electrode contactor contacts, the internal switch output can be obtained, so that a large error will not occur and an accident will not occur. It can also be measured even if the object to be measured is an insulator.

[Brief explanation of drawings]

Figures 1a and b are schematic diagrams showing an example of a conventional position detection device, Figures 2a and b are views taken along lines A-A and B-B in Figure 1a, and Figure 3 is a schematic diagram showing an example of a conventional position detection device. A block diagram showing an example of a position detection circuit using the device, FIGS. 4a and b, FIGS. 5 and 10 are schematic diagrams showing an embodiment of the present invention, and FIG. A block diagram showing the position detection circuit, FIGS. 7a and 7b are explanatory diagrams of the operation of the above embodiment, and FIGS. 8, 9 and 11 are schematic diagrams showing main parts of other embodiments of the present invention. 12 is an actual measurement graph showing the relationship between the operating stress S and the position detection error E, and FIG. 13 is a circuit diagram showing still another embodiment of the present invention. 21... Electrode contact, 22... Stylus, 23
... Disk, 24 ... Rotating curved body, 26 ... Housing.

Claims (1)

[Scope of Claims] 1. A conductive electrode contactor is held by a holding means in a housing via a stylus, and the conductivity between the electrode contactor and the object to be measured changes due to contact with the object, or the above-mentioned at this time. In a position detection device that generates a signal in response to displacement of a holding means, the electrode contactor is made of a conductive sphere, and the holding means is connected to first and second holding means that are in pressure contact with each other in a housing. The first holding member has a concentric spherical surface with the electrode contactor, the second holding member is in line contact with the concentric spherical surface, and one of the holding members has a conductive member. A film is formed,
A position detection device characterized in that the other is made of an insulating material and is configured to detect a signal responsive to contact between the workpiece and the electrode contact from the stylus and/or the conductive film. 2. Claims characterized in that the conductive film is provided at a plurality of divided positions on the one holding member, and each conductive film and a lead wire from the stylus are connected to an OR circuit. The position detection device according to item 1. 3. The position detection device according to claim 2, wherein a lead wire from the stylus is connected to the OR circuit via a switch. 4. The position detection device according to claim 2, wherein the position detection device is configured to generate an alarm when there is an output on the lead wire from the conductive film.