JP2534820B2 - Touch signal probe - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch signal probe, and more particularly to a touch signal probe used when measuring the shape of an object to be measured with a coordinate measuring machine or the like.

[0002]

BACKGROUND ART Height gauges (one-dimensional measuring machines), three-dimensional measuring machines, contour measuring machines, etc. are known as measuring machines for measuring the shape and dimensions of an object to be measured, and coordinate detection and position in that case. In order to perform the detection, a touch signal probe that detects a contact with an object to be measured and outputs a touch signal is used in the measuring machine.

FIG. 4 is a schematic perspective view showing the principle of a touch signal probe of a conventional three-point seating mechanism. As shown in FIG. 4, in the touch signal probe of the three-point seating mechanism, a pair of pins 10 are provided at 120 ° intervals in a probe case (not shown).
A total of three sets of A and 10B are arranged, and a locking rod 14 extending from the holder 12 is engaged with these pins 10A and 10B. A stylus 16 extending downward is attached to the lower surface of the holder 12, and a contact ball 18 that comes into contact with an object to be measured at the time of measurement is attached to the tip of the stylus 16.

Further, the upper portion of the holder 12 is elastically biased downward by a coil spring 20 disposed inside a probe case (not shown), whereby the locking rod 14 presses the pins 10A and 10B with a constant pressing force. It is pressed and engaged with. Further, a cord 22 is connected between the pins 10A and 10B, and a detection circuit 24 for transmitting a contact signal when the contact ball 18 contacts the object to be measured is connected to both ends of the cord 22. There is.

Therefore, when an external force is applied to the contact ball 18 by the contact ball 18 coming into contact with the object to be measured, the holder 12
Tilts against the elastic biasing force of the coil spring 20, whereby any one of the three locking rods 14 has a pin 10A,
After disconnecting from 10B, the continuity between the cords 22 is cut off, which is detected by the detection circuit 24. When the external force is removed, the holder 12 is returned to its original position by the elastic biasing force of the coil spring 20 so that each locking rod 14 is locked by each pin 1.
By engaging with 0A and 10B, conduction between the pins 10A and 10B is restored.

[0006]

On the other hand, in the touch signal probe, after the contact ball 18 comes into contact with the object to be measured, an escape operation for retracting the stylus 16 from the object to be measured is required. The ease of mounting is mainly determined by the pressing force of the coil spring 20, that is, the elastic biasing force. Therefore, to facilitate the escape operation, the coil spring 2
Although it is conceivable to weaken the elastic biasing force of 0, if the elastic biasing force of the coil spring 20 is weakened more than necessary, even the slight inertial force generated when the probe moves causes the stylus 1 to move.
6 moves, and as a result, erroneous detection occurs, which makes it impossible to move the touch signal probe at high speed, which requires a long time for measurement. On the contrary, if the elastic biasing force of the coil spring 20 is strengthened so as not to be affected by the inertial force, the contact force at the time of contacting the object to be measured becomes large and the stylus 16 escapes reliably after the contact. Since this is not done, there is a risk of damaging the DUT during overtravel.

The present invention has been made in view of the above circumstances, and the escape operation of the contact point at the time of contact is reliably performed, erroneous detection is prevented, measurement with low contact force is possible, and measurement time is reduced. There is a touch signal probe that can be shortened.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a fixing element for supporting a holder, on which a probe contacting an object to be measured is attached, is provided in a probe case, and the holder is elastic on the fixing element. In a touch signal probe in which an elastic member for urging is disposed in the probe case and the measuring element detects a contact with an object to be measured and sends a contact signal, the probe case or the holder is A permanent magnet that attracts the holder in the direction of urging the fixing element, and a coil that is energized when a contact signal is sent from the detection means to cancel the magnetic force of the permanent magnet are provided. It has a feature.

[0009]

In the present invention, as means for urging the holder in the direction of the fixing element, in addition to the elastic member arranged in the probe case, a permanent magnet for attracting the holder in the direction of the fixing element is used as the probe case or the holder. It is provided in. That is, when the contact point and the object to be measured are not in contact with each other, the holder is urged to the fixed element by the attraction force of the permanent magnet in addition to the elastic urging force of the elastic member. Inclination of the holder due to inertial force at the time is prevented, and erroneous detection is reduced. Further, since the coil for canceling the magnetic force of the permanent magnet when the contact signal with the object to be measured is sent from the detecting means is arranged in the probe case or the holder, when the contact point contacts the object to be measured. The attraction force of the permanent magnet is released, and the holder is biased to the fixing element only by the biasing force of the elastic member. As a result, since the escape operation of the holder is surely performed during overtravel, it is possible to measure a soft object without damaging the object to be measured.

[0010]

Next, preferred embodiments of a touch signal probe according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a partially broken perspective view showing an outline of a touch signal probe according to this embodiment, FIG. 2 is a side sectional view of the touch signal probe of FIG. 1, and FIG. 3 is a circuit configuration of the touch signal probe of FIG. It is explanatory drawing which shows the outline of.

As shown in FIG. 1, the touch signal probe 25 according to this embodiment includes a probe case 26 and a holder 2.
8 and the stylus 30 and the like. Probe case 26
Is composed of a case body 26A, an upper plate 26B, and a lower plate 26C, and a through hole 31 is formed in the lower plate 26C. The stylus holder 30A of the probe 30 attached to the lower surface of the holder 28 is provided in the through hole 31. It has been inserted. Further, the lower plate 26C has two small balls 3 as fixing elements for the holder 28.
2 are provided at three places at 120 ° intervals.

Further, the holder 28 is formed in a disk shape, and on its peripheral surface, three support rods 34 engaging with the small balls 32, 32 are radially provided at 120 ° intervals.
A coil spring 33 serving as an elastic member is disposed between the holder 28 and the upper plate 26A of the probe case 26. The coil spring 33 elastically biases the holder 28 downward to move the support rod 34 into a small ball. 32 is engaged and supported with a predetermined biasing force. A stylus 30B having a contact ball 30C is attached to the lower end of the stylus holder 30A.

On the other hand, on the lower plate 26C of the probe case 26, as shown in FIG. 2, the electromagnets 3 are provided at three positions at 120 ° intervals.
5 is arranged with a space from the holder 28. The electromagnet 35 is configured by winding a coil 38 around a permanent magnet 36, and the permanent magnet 36 generates a magnetic force that attracts the holder 28 in a direction in which the holder 28 is in contact with the small ball 32 that is a fixing element. Therefore, the holder 28 is pressed and urged downward by the resultant force of the magnetic force of the permanent magnet 36 and the elastic urging force of the coil spring 33, so that the support rod 34 of the holder 28 is securely attached to the small ball 32. To engage.

A strain gauge 40 for detecting contact with the object to be measured is attached to the stylus 30B. By using the strain gauge 40 to detect the strain generated in the stylus 30B when the contact ball 30C contacts the object to be measured. The contact with the object to be measured is detected. That is, the strain gauge 40
Is connected to a detection circuit 42 described later, and this detection circuit 42
The contact with the object to be measured is detected by.

The touch signal probe 25 detects the contact with the object to be measured by the strain gauge 40, the strain of the stylus 30B is detected by a detection element such as a piezoelectric element, or the stylus 30B is measured. Any probe may be used, such as a probe that resonates in advance and detects a contact with the object to be measured by detecting a change in amplitude caused by the contact of the contact sphere 30C with the object to be measured with a detection element.

On the other hand, the coil 38 of the electromagnet 35 is connected to the energizing circuit 44 via the cord 46, and the energizing circuit 44 is further connected to the detecting circuit 42. Therefore, when the strain gauge 40 detects a strain in the stylus 30B that is equal to or greater than a predetermined value, the detection circuit 42 first sends a contact signal to the energization circuit 44. Then, the energizing circuit 44
Receives this contact signal and applies a current to the coil 38,
The magnetic force in the direction that cancels the magnetic force of the permanent magnet 36 is applied to the electromagnet 35.
Then, the attraction force by the permanent magnet 36 is released.

The operation of the touch signal probe according to this embodiment constructed as described above is as follows.

In order to measure the shape or the like of the object to be measured, the touch signal probe 25 is attached to a spindle of a coordinate measuring machine (not shown) and is moved by the spindle to the object to be measured placed on the surface plate. During the movement to the object to be measured, a downward biasing force is applied to the holder 28 by both the coil spring 33 and the permanent magnet 36 as shown in FIG. It is engaged and supported.

That is, since the holder 28 is pressed downward due to the elastic biasing force of the coil spring 33 and the attracting force of the permanent magnet 36, the holder 28 is supported even when the touch signal probe 25 is moved at a high speed. The rod 34 is kept in engagement with the two small balls 32 that are fixing elements. As a result, careless inclination of the tracing stylus 30 can be prevented, and high-speed movement is possible, so that the measurement time is shortened.
In addition, the holder 28 does not depend on electric power or the like, and the permanent magnet 36
Since it is simply adsorbed in the direction of the small balls 32, there is an advantage that the temperature does not rise and the running cost is low.

When the contact ball 30C of the probe 30 comes into contact with the object to be measured, the stylus 30B is distorted. This distortion is detected by the strain gauge 40, and the detection circuit 42 shown in FIG. 3 makes contact with the object to be measured. The signal is sent to the energizing circuit 44. Then, the energizing circuit 44 outputs an instruction signal to energize the coil 38 with a predetermined current, and the energizing circuit 44 energizes the coil 38 of the electromagnet 35 with current based on the instruction signal. When a current is applied to the coil 38, the coil 38 generates a magnetic force in a direction that cancels the magnetic force of the permanent magnet 36, so that the urging force of the holder 28 by the permanent magnet 36 is released, and the holder 28 is moved downward only by the coil spring 33. It will be in a state of being biased to.

As a result, the biasing force of the holder 28 against the small balls 32 is reduced, and the escape operation of the holder 28 during overtravel is reliably performed. This eliminates the possibility of damaging the object to be measured and enables measurement even when the object to be measured is a soft material or the like.

When the measurement is completed, the external force generated on the probe 30 is removed, so that the holder 28 as shown in FIG.
Is returned to the original position by the elastic biasing force of the coil spring 33, and the detection circuit 42 detects that the probe 30 is not in contact with the object to be measured. Then, the detection circuit 42 outputs to the energizing circuit 44 an instruction signal for canceling the energization of the coil 38.

When the coil 38 is de-energized, the holder 28 is urged downward not only by the elastic urging force of the coil spring 33 but also by the attraction force of the permanent magnet 36, and the support rod 34 is moved by the small balls 32. Securely engages. Therefore, the careless inclination of the tracing stylus 30 during non-measurement is prevented.

As described above, according to the present embodiment, since the biasing force of the coil spring 33 can be weakened, the escape operation of the holder 28 at the time of overtravel is surely performed, and the measurement with a low contact force becomes possible. The detection sensitivity is improved. Furthermore,
When the holder 28 is not in contact with the object to be measured, the holder 28 is reliably supported by the small ball 32 as a fixing element, so that the holder 28 is prevented from being inadvertently tilted when the touch signal probe 25 is moved.

Although the present invention has been described with reference to the preferred embodiment, the present invention is not limited to this embodiment, and various improvements and design changes can be made without departing from the scope of the present invention. Of course it is possible.

For example, in the present embodiment, the case where the present invention is applied to a three-dimensional measuring machine has been described, but the present invention is not limited to this and can be applied to a height gauge (one-dimensional measuring machine), a contour measuring machine and the like. Further, in the present embodiment, the electromagnet 35 is used as a means for attracting the holder 28, but the present invention is not limited to this, and the support rod 34 of the holder 28 is reliably engaged with the small ball 32 during non-measurement such as mechanical structure. Any structure may be used as long as it can be made. In addition, although the electromagnet 35 is arranged on the probe case 26 in this embodiment, the electromagnet 35 may be arranged on the holder 28 side.

Further, in this embodiment, the small ball 3 is used as a fixing element.
2, the support rod 34 of the holder 28 is engaged with and supported by the small ball 32.
Any structure may be used as long as it can be supported at a predetermined position inside. In addition, in this embodiment, three electromagnets 35 and the lower plate 26 are used.
Although the case where it is installed in C has been described, one annular electromagnet that surrounds the probe 30 may be used, or the number of electromagnets may be further increased.

[0029]

As described above, according to the present invention,
The escape operation is reliably performed during overtravel, and as a result, measurement with low contact force is possible. Also,
Since the careless tilt of the probe is prevented, erroneous detection is reduced, the measurement accuracy is improved, and the touch signal probe can be moved at high speed, and the measurement time is shortened.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an outline of a touch signal probe according to an embodiment.

FIG. 2 is a side sectional view of the touch signal probe of FIG.

FIG. 3 is an explanatory diagram showing an outline of a circuit configuration in the touch signal probe of FIG. 1.

FIG. 4 is a schematic perspective view showing the principle of a touch signal probe of a conventional three-point seating mechanism.

[Explanation of symbols]

 25 Touch Signal Probe 26 Probe Case 26C Lower Plate 28 Holder 30 Measuring Element 32 Small Ball (Fixing Element) 33 Coil Spring (Elastic Member) 34 Support Rod 35 Electromagnet (Biasing Means) 36 Permanent Magnet 38 Coil 40 Strain Gauge (Detecting Means) ) 42 detection circuit (detection means)

Claims (1)

(57) [Claims] 1. A probe case is provided with a fixing element for supporting a holder to which a probe contacting an object to be measured is attached, and an elastic member for elastically urging the holder onto the fixing element is provided in the probe case. In a touch signal probe having a detection means that is disposed inside and detects contact between the probe and an object to be measured, and sends a contact signal, the probe case or the holder has the holder as the fixing element. A touch signal probe, comprising: a permanent magnet that attracts in a biasing direction; and a coil that is energized when a contact signal is sent from the detection means to cancel the magnetic force of the permanent magnet.