JP7300850B2 - Detection device and clamping device - Google Patents

Description

The present invention relates to a detection device and a clamping device with proximity switches.

Conventionally, there has been known a proximity switch (proximity sensor) that determines the presence or proximity of a conductive detection object such as metal (see, for example, Patent Document 1). The proximity switch detects the presence or approach of the detection object by detecting a change in the impedance or Q value of the detection coil accompanying the presence or approach of the detection object in the detection unit. The Q value is a value that indicates inductance loss due to electromagnetic induction, and the higher the Q value, the smaller the loss.
Also, depending on the intended use, the proximity switch detects the distance between the detection object and a reference point on the proximity switch. The reference point is, for example, a point on the surface of the stainless steel cover at the tip of the detection section that faces the detection object.

There is also known a proximity switch that uses a threshold corresponding to the type of metal to improve the determination performance for a detection object made of a specific metal (see Patent Document 2, for example). Note that this proximity switch uses one threshold value, and is capable of detecting one type of metal among a plurality of metals in practical use.

JP 2010-216863 A JP 2017-130897 A

Since the conventional proximity switch uses one threshold value, it is not possible to distinguish and detect multiple states of the detected object. Therefore, when it is desired to distinguish and detect a plurality of states of the detection object, it is necessary to use a plurality of proximity switches. For example, if it is desired to use conventional proximity switches to detect the opening and closing of a clamp such as a collet chuck clamp or a turret clamp, multiple proximity switches must be used.

SUMMARY OF THE INVENTION An object of the present invention is to provide a detection device capable of distinguishing and detecting a plurality of states of a detection object with a single proximity switch.

A detection device according to the present invention includes a proximity switch and a conductive detection body that is radially movable with respect to a detection surface of the proximity switch, and the proximity switch faces the detection surface within a housing. An arranged detection coil, an oscillation circuit that oscillates and generates a high-frequency magnetic field in the detection coil, a detection circuit that detects the amplitude of the oscillation by the oscillation circuit, and a plurality of threshold values for the amplitude detected by the detection circuit, respectively. Signals indicating whether the amplitude detected by the detection circuit is within a plurality of output ranges composed of the plurality of thresholds are output based on the results of comparison between the comparison circuit to be compared and the plurality of thresholds by the comparison circuit. and a setting input unit for setting a plurality of thresholds for the comparison circuit, and the comparison circuit converts the amplitude detected by the detection circuit to a first threshold and a value different from the first threshold. is compared with a third threshold value between the first threshold value and the second threshold value, and the upper limit value, and the output circuit outputs a plurality of threshold values obtained by the comparison circuit. A signal indicating whether the amplitude detected by the detection circuit is within a first output range composed of a first threshold and a second threshold, a third threshold and an upper limit based on the comparison result of It is characterized by outputting a signal indicating whether it is within a second output range composed of values .

According to the present invention, since it is configured as described above, it is possible to distinguish and detect a plurality of states of the detection object with a single proximity switch.

1 is a diagram showing a configuration example of a detection device according to Embodiment 1; FIG. 3 is a diagram showing a configuration example of a proximity switch according to Embodiment 1; FIG. 4 is a diagram showing an example of a correspondence relationship between outputs from two output terminals of an output circuit and the position of a detected object in the detection device according to Embodiment 1. FIG. 4A is a diagram showing a case where the detection object is positioned at the center position (0 mm) of the detection surface of the proximity switch in the detection device according to Embodiment 1, and FIG. 4B is a diagram showing the proximity switch in the case of FIG. 4A It is a figure which shows the detection value by. 5A is a diagram showing the case where the detection object is located at a point 3.2 mm from the center position of the detection surface of the proximity switch in the detection device according to Embodiment 1, and FIG. 5B is the case of FIG. 5A. is a diagram showing a detection value by the proximity switch of. 6A is a diagram showing the case where the detection object is located at a point 6.4 mm from the center position of the detection surface of the proximity switch in the detection device according to Embodiment 1, and FIG. 6B is the case of FIG. 6A. is a diagram showing a detection value by the proximity switch of. 7A is a diagram showing a case where the detection object is located at a point 9.6 mm from the center position of the detection surface of the proximity switch in the detection device according to Embodiment 1, and FIG. 7B is the case of FIG. 7A. is a diagram showing a detection value by the proximity switch of. 4 is a diagram for explaining threshold setting for proximity switches in Embodiment 1. FIG. FIG. 2 is a diagram showing a configuration example of a clamp device to which the detection device according to Embodiment 1 is applied; 10A and 10B are diagrams showing an example of the relationship between the position of the detection object and the opening and closing of the clamp when the detection device according to Embodiment 1 is applied to the clamp device. 10B is a diagram showing a case where the clamp is closed; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a detection device according to Embodiment 1. FIG.
The detection device detects the position of the detection body 2 . The detection device comprises a proximity switch 1 and a detection body 2, as shown in FIG.

The proximity switch 1 enables detection of the position of the detection body 2 . That is, the proximity switch 1 changes its output depending on the position of the detection body 2 . The proximity switch 1 has a detecting portion 11 which is a sensor head, a cable 12 having one end connected to an input/output end of the detecting portion 11, and a plurality of output pins 13 connected to the other end of the cable 12. there is The proximity switch 1 has a limited number of output pins 13 like IO-Link. In addition, among the plurality of output pins 13 of the proximity switch 1, there are two output pins 13 that can be used for signal output. A more detailed configuration example of the proximity switch 1 will be described later.

The detection body 2 is an object that can move radially with respect to the detection surface (the end surface of the detection portion 11) of the proximity switch 1. As shown in FIG. That is, the detection body 2 is assumed to be an object that has a minute surface opposite to the detection surface of the proximity switch 1 and moves minutely. Also, the detection body 2 is a conductive object such as metal. The detection body 2 is configured, for example, in a bar shape (including a needle shape) having a minute surface facing the detection surface of the proximity switch 1 .

Next, a configuration example of the proximity switch 1 will be described with reference to FIG.
As shown in FIG. 2, the proximity switch 1 includes a detection coil 101, a power supply 102, a stabilized power supply circuit 103, an oscillation circuit 104, a detection circuit 105, a comparison circuit 106, an output circuit 107, and two systems of transistors 108 (transistor 108a and transistor 108b), and a setting input unit 109. FIG. The proximity switch 1 is also connected to two systems of resistors 3 (resistors 3a and 3b).

The detection coil 101 is cylindrically wound around a core (not shown), and is arranged inside the housing of the detection section 11 so as to face the detection surface.
The stabilized power supply circuit 103 operates with power supplied from the power supply 102 and supplies power of a predetermined voltage to the oscillation circuit 104 , the detection circuit 105 and the comparison circuit 106 .

The oscillation circuit 104 oscillates and causes the detection coil 101 to generate a high-frequency magnetic field. When the detection body 2 approaches the high-frequency magnetic field generated by the detection coil 101 , an induced current flows through the detection body 2 and causes heat loss. Oscillation is damped. Note that the oscillation circuit 104 may be configured to maintain oscillation even when the detection object 2 comes closest, and to change the amplitude of oscillation according to changes in the impedance or Q value of the detection coil 101. .
In addition, when the minute detection object 2 faces the detection surface of the proximity switch 1, and when the detection object 2 is positioned near the center of the detection surface, the detection object 2 is far from the detection coil 101, so the Q value is high, and when the detection body 2 is positioned at the end of the detection surface, the detection body 2 is close to the detection coil 101, so the Q value is low.

A detection circuit 105 detects the amplitude of oscillation by the oscillation circuit 104 . That is, the detection circuit 105 converts the amplitude of the oscillation by the oscillation circuit 104 into a direct current and rectifies it.

The comparison circuit 106 compares the amplitude (detection value) detected by the detection circuit 105 with a plurality of thresholds (first to third thresholds and upper limit). The second threshold is a threshold with a value different from the first threshold. The third threshold is a threshold value between the first threshold and the second threshold. Note that each threshold (first threshold to third threshold) is set by the setting input unit 109 .

The output circuit 107 outputs a signal indicating whether the amplitude detected by the detection circuit 105 is within each output range based on the result of comparison with each threshold by the comparison circuit 106 . Each output range is a range composed of respective threshold values.
Specifically, the output circuit 107 outputs an ON signal from one of the two output terminals when the amplitude detected by the detection circuit 105 is within the first output range. Also, the output circuit 107 outputs an ON signal from the other of the two output terminals when the amplitude detected by the detection circuit 105 is within the second output range. The first output range is a range composed of a first threshold and a second threshold. Also, the second output range is a range composed of the third threshold value and the upper limit value. That is, the first output range and the second output range partially overlap each other. FIG. 3 shows an example of the correspondence relationship between the output from the two output terminals of the output circuit 107 and the position of the detection object 2. In FIG.

In FIG. 3, as an output (first output) from one of the two output terminals of the output circuit 107, a state in which an ON signal is output is ON, and a state in which an ON signal is not output is OFF. and As the output (second output) from the other of the two output terminals of the output circuit 107, the state in which the ON signal is output is ON, and the state in which the ON signal is not output is OFF. .

The transistor 108 a has a gate terminal connected to one of two output terminals of the output circuit 107 and an emitter terminal connected to the positive terminal of the power supply 102 . The transistor 108 a is driven by an ON signal from one of two output terminals of the output circuit 107 .

The transistor 108 b has a gate terminal connected to the other of two output terminals of the output circuit 107 and an emitter terminal connected to the positive terminal of the power supply 102 . The transistor 108b is driven by an ON signal from the other of the two output terminals of the output circuit 107. FIG.

A setting input unit 109 sets each threshold for the comparison circuit 106 . The setting input unit 109 can set each threshold at the site where the proximity switch 1 is used. The setting input section 109 has a trigger reception section 1091 and a threshold setting section 1092 .

The trigger reception unit 1091 receives input of a trigger. As the trigger reception unit 1091, for example, a communication unit that receives information from an external terminal, or a setting trigger device such as a push button can be used.

The threshold setting unit 1092 detects the amplitude value detected by the detection circuit 105 each time the trigger reception unit 1091 receives a trigger input, and sets each threshold for the comparison circuit 106 based on the detected amplitude value. set. The threshold value setting unit 1092 is implemented by a processing circuit such as a system LSI (Large Scale Integration) or a CPU (Central Processing Unit) that executes a program stored in a memory or the like.

At this time, the threshold value setting unit 1092 sets the values between the amplitude values so that the respective output ranges of the output circuit 107 partially overlap with each other. are set as thresholds, which are values excluding the upper limit value.
Alternatively, the threshold value setting unit 1092 sets the value of each amplitude to the maximum of each lower limit value and each upper limit value constituting each output range so that each output range of the output circuit 107 partially overlaps with each other. You may set each as a threshold value which is a value except a value.

One end of the resistor 3a is connected to the collector terminal of the transistor 108a, and the other end is connected to the minus terminal of the power supply 102. FIG. Power is supplied to the resistor 3a from the power supply 102 by driving the transistor 108a.
The resistor 3b has one end connected to the collector terminal of the transistor 108b and the other end connected to the negative terminal of the power supply 102. FIG. Power is supplied to the resistor 3b from the power supply 102 by driving the transistor 108b.
Examples of the resistors 3a and 3b include loads such as PLCs (Programmable Logic Controllers) and relays.

The proximity switch 1 can detect the position of the detection object 2 existing in the detection area from the power supplied to the resistors 3a and 3b. In the case where the proximity switch 1 has two outputs as shown in FIG. 1, as shown in FIG. presence can be detected.

Next, a method of setting each threshold (first threshold to third threshold) by the setting input unit 109 according to Embodiment 1 will be described. 4 to 7 are diagrams showing an example of changes in the detection value of the proximity switch 1 when the position of the detection body 2 with respect to the proximity switch 1 is changed. FIGS. 4 to 7 show cases where a bar-shaped detection body 2 is used and this detection body 2 is moved to the right from the position shown in FIG. In the graphs shown in FIGS. 4 to 7, the horizontal axis indicates the position of the detection body 2, and the vertical axis indicates the detection value of the proximity switch 1. FIG. The position of the detection body 2 is the radial position from the center position of the detection surface of the proximity switch 1 .

In the following description, the operator places the detection body 2 at a position where detection is actually desired, the proximity switch 1 obtains the detection value at that time, and the threshold value setting unit 1092 sets each output range of the output circuit 107 to match each other. The values between the amplitude values are set so as to overlap each other, and the upper limit value (upper limit value constituting the second output range) of each lower limit value and each upper limit value constituting each output range is set so as to overlap. A case where each is set as a threshold that is a value to be excluded is shown.

In this case, as shown in FIG. 4, the operator first positions the detection body 2 at the center position of the detection surface of the proximity switch 1 (first position). Then, the operator inputs a trigger to the trigger reception unit 1091, and the proximity switch 1 obtains the value of the amplitude of oscillation at that time (the first detection value indicated by reference numeral 401).
Next, as shown in FIG. 5, the operator positions the detection body 2 at a point approximately 3.2 mm in the radial direction from the center position of the detection surface of the proximity switch 1 (second position). Then, the operator inputs a trigger to the trigger reception unit 1091, and the proximity switch 1 obtains the value of the amplitude of oscillation at that time (the second detection value indicated by reference numeral 501).
After that, as shown in FIG. 8, the threshold value setting unit 1092 sets the value between the first detection value and the second detection value to the lower limit value (first threshold).

Next, as shown in FIG. 6, the operator positions the detection body 2 at a point approximately 6.4 mm in the radial direction from the center position of the detection surface of the proximity switch 1 (third position). Then, the operator inputs a trigger to the trigger reception unit 1091, and the proximity switch 1 obtains the value of the amplitude of oscillation at that time (the third detection value indicated by reference numeral 601).
After that, as shown in FIG. 8, the threshold value setting unit 1092 sets the value between the second detection value and the third detection value to the lower limit value (third threshold).

Next, as shown in FIG. 7, the operator positions the detection body 2 at a point approximately 9.6 mm in the radial direction from the center position of the detection surface of the proximity switch 1 (fourth position). Then, the operator inputs a trigger to the trigger reception unit 1091, and the proximity switch 1 obtains the value of the amplitude of oscillation at that time (the fourth detection value indicated by reference numeral 701).
After that, as shown in FIG. 8, the threshold value setting unit 1092 sets the value between the third detection value and the fourth detection value to the upper limit value (second threshold).
As described above, the setting input unit 109 can set each threshold that constitutes the first output range and the second output range.

In the above description, the threshold value is set by placing the detected object 2 at a position between the lower limit value and the upper limit value that constitute the output range (that is, the position where the detected object 2 is actually desired to be detected). However, the method of setting the threshold is not limited to this, and the threshold may be set at the positions of the lower limit and upper limit that constitute the output range of the detection body 2 .

As described above, in the detection device according to the first embodiment, the detection body 2 that is radially movable with respect to the detection surface of the proximity switch 1 is used, and tuning is performed at a plurality of positions with this detection body 2. (For example, the intermediate value of the detected values is automatically set as the threshold value). As a result, in the detecting device according to the first embodiment, the single proximity switch 1 can detect the position of the detection object 2 by distinguishing it in a plurality of ranges. function is obtained.

It is preferable that the detection body 2 is formed in a rod shape having a minute surface opposite to the detection surface of the proximity switch 1 .

Next, an application example of the detection device according to Embodiment 1 will be described.
For example, as shown in FIG. 9, the detection device according to the first embodiment can be applied to a clamp device 5 having a clamp 51 that attaches and detaches a work (not shown) by moving in the axial direction. Examples of this clamping device 5 include a collet chuck clamp or a turret clamp.
As shown in FIG. 9, the clamp device 5 has a clamp 51 that attaches and detaches workpieces by moving in the axial direction, and a moving shaft 52 that is connected to the clamp 51 . Then, as shown in FIG. 10 , the detection body 2 is attached to the moving shaft 52 in a direction perpendicular to the moving shaft 52 .

As described above, the detection device according to Embodiment 1 is applied to the clamp device 5 having the clamp 51 that attaches and detaches the workpiece by moving in the axial direction, so that the moving shaft 52 to which the detection body 2 is attached is Since it moves according to the opening and closing of the clamp 51 , the detection device can detect the opening and closing of the clamp 51 .

That is, for example, as shown in FIG. 10A, it can be determined that the clamp 51 is open when the detection body 2 is positioned at the edge of the detection surface of the proximity switch 1. FIG. For example, as shown in FIG. 10B, when the detection body 2 is positioned near the center of the detection surface of the proximity switch 1, it can be determined that the clamp 51 is closed.
Note that FIG. 10 shows a case where the proximity switch 1 of the detection device is tuned at two points within the detection plane of the proximity switch 1 . On the other hand, tuning may be performed at three points including the case where the detection object 2 deviates from the detection surface of the proximity switch 1 .

As described above, according to the first embodiment, the detection device includes the proximity switch 1 and the detection body 2 having conductivity and being radially movable with respect to the detection surface of the proximity switch 1. The proximity switch 1 includes a detection coil 101 arranged opposite to the detection surface in the housing, an oscillation circuit 104 that oscillates and generates a high-frequency magnetic field in the detection coil 101, and the amplitude of the oscillation by the oscillation circuit 104 is detected. a comparator circuit 106 for comparing the amplitude detected by the detector circuit 105 with a plurality of threshold values; and the amplitude detected by the detector circuit 105 based on the results of comparison with the plurality of threshold values by the comparator circuit 106 is within a plurality of output ranges composed of the plurality of thresholds, and a setting input unit 109 for setting a plurality of thresholds for the comparison circuit 106 . As a result, the detection device according to the first embodiment can distinguish and detect a plurality of states of the detection object 2 with a single proximity switch 1 .

It should be noted that, within the scope of the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted.

1 Proximity switch 2 Detector 3, 3a, 3b Resistor 5 Clamp device 11 Detector 12 Cable 13 Output pin 51 Clamp 52 Moving axis 101 Detection coil 102 Power supply 103 Stabilized power supply circuit 104 Oscillation circuit 105 Detection circuit 106 Comparison circuit 107 Output Circuits 108, 108a, 108b Transistor 109 Setting input section 1091 Trigger reception section 1092 Threshold setting section

Claims (3)

a proximity switch;
a detection body having electrical conductivity and movable in a radial direction with respect to a detection surface of the proximity switch;
The proximity switch is
a detection coil arranged opposite to the detection surface in the housing;
an oscillation circuit that oscillates to generate a high-frequency magnetic field in the detection coil;
a detection circuit for detecting the amplitude of oscillation by the oscillation circuit;
a comparison circuit that compares the amplitude detected by the detection circuit with a plurality of threshold values;
an output circuit for outputting a signal indicating whether the amplitude detected by the detection circuit is within a plurality of output ranges composed of the plurality of thresholds, based on the results of comparison with the plurality of thresholds by the comparison circuit; ,
a setting input unit for setting a plurality of threshold values for the comparison circuit;
The comparator circuit compares the amplitude detected by the detector circuit with a first threshold value, a second threshold value different from the first threshold value, and the first threshold value and the second threshold value. Compare the third threshold, which is a value between, with the upper limit,
The output circuit is configured such that the amplitude detected by the detection circuit falls within a first output range composed of the first threshold and the second threshold, based on the results of comparison with a plurality of thresholds by the comparison circuit. and a signal indicating whether the output range is within a second output range composed of the third threshold value and the upper limit value. 2. The detection device according to claim 1 , wherein the detection body is formed in a rod shape having a minute surface facing the detection surface. A clamp that attaches and detaches workpieces by moving in the axial direction,
a moving shaft coupled to the clamp;
A detection device according to claim 1 or claim 2 ,
A clamping device, wherein the detection body is attached in a direction perpendicular to the movement axis with respect to the movement axis.

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