JPH0729446Y2 - Position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a position detection device used for detecting a fixed position of a workpiece during machining or the like.

(Prior Art) Conventionally, as a position detection device for determining whether or not a work is accurately seated at a predetermined position when fixing a workpiece (hereinafter referred to as a work) to a machine tool, a press machine, or the like. , A detection nozzle is provided at a predetermined position close to the end face of the work, etc., which is connected to a reduced pressure or pressurized air source and can detect the air pressure on the original side of the detection nozzle. , For example, when the proximity of 0.05mm or less, the change in the air pressure on the nozzle side is detected due to the change in the resistance of the air passing through the nozzle.
The position of the work is detected.

In order to detect such a change in the air pressure on the detection nozzle base side quickly and sharply, a position detecting device having an air bridge circuit having a structure as shown in FIG. 3 has been used.
That is, this position detecting device includes a comparative air passage a communicating from the air source 1 through the first fixed throttle means 3 and the variable throttle means 5 to the outside of the device, and the air source 1 to the second fixed throttle means 2 and the proximity position detection. Detection air passage b communicating with the outside through the nozzle 4
A comparative pressure passage c leading from the intermediate position 7 between the first fixed throttle means 3 and the variable throttle means 5 to the comparative pressure inlet 81 of the differential pressure sensor 8, the second fixed throttle means 2 and the proximity position detection nozzle 4. From the intermediate position 6 of the detection pressure introducing port 82 of the differential pressure sensor 8
It is provided with an air bridge circuit consisting of a detection pressure passage d leading to the. Note that W is a work.

In this conventional position detecting device, orifices or capillaries are used as the first fixed throttle means 3 and the second fixed throttle means 2, and the variable throttle means 5 is a semi-fixed needle as shown in FIG. A valve was used. Here, 51 is a valve body, which is provided with a female screw portion 52 which is screwed with a male screw portion 54 provided around the needle 53, and a screwdriver 55 is applied to a split groove 55 formed at the rear end of the needle 53 to rotate. The flow resistance of the air can be adjusted by this.

(Problems to be Solved by the Invention) The conventional position detecting device including the air bridge circuit as described above has a relatively simple structure and can be configured in a small size. The valve is used to adjust the comparison pressure, and thereby the detection position of the position detection device can be adjusted.

However, if the needle valve is small, its structural accuracy must be extremely increased, which is disadvantageous in that it becomes expensive. There is also a problem that the detection accuracy is lowered when the detection position is changed significantly.

Therefore, an object of the present invention is to provide at low cost a position detection device that can maintain high detection accuracy even if the detection position is significantly changed and that can change the detection position very easily and accurately.

(Means for Solving the Problem) In order to achieve the above-mentioned object, in the present invention, a comparison air passage communicating from the air source to the outside through the first fixed throttle means and the variable throttle means, and the air source From the intermediate position between the first fixed throttle means and the variable throttle means to the comparative pressure introduction port of the differential pressure sensor, the detection air passage leading to the outside of the device via the second fixed throttle means and the proximity position detection nozzle connection port. An air bridge circuit having a comparison pressure passage and a detection pressure passage communicating from a middle position between the second fixed throttle means and the proximity position detection nozzle connection port to the detection pressure introduction port of the differential pressure sensor, The throttle means is a rotary dial body around which a nozzle, a flapper surface facing the nozzle, and a scale are provided, and is formed such that the gap between the nozzle and the flapper surface changes in accordance with the rotation angle. What was done Consists of
The position detection device is configured such that a part of the outer circumference of the rotary dial body is exposed to the outside of the device.

(Operation) The position detecting device of the present invention continuously changes the distance between the nozzle of the variable throttle means and the flapper surface by rotating the dial, thereby continuously changing the air flow resistance of the variable throttle means. It was done like this.

In the air bridge circuit provided with such variable throttle means in the comparison air passage, the advantage that the detection sensitivity of the proximity position detection nozzle is hardly affected even if the air pressure of the air source is slightly changed is maintained. The detection sensitivity and the proximity position of the work can be adjusted extremely easily and with good reproducibility.

(Embodiment) FIG. 1 shows the structure of the position detecting device of the present invention.

In the figure, the configuration of the air bridge circuit is basically the third
Although it is equivalent to that shown in the figure, 9 is a variable diaphragm means of the present invention, 91 is a nozzle, 92 is a rotary dial body, 93 is a flapper surface formed on the circumference of the rotary dial body, and 94 is It is the axis of rotation of the rotary dial body. The structure of the variable diaphragm means 9 is schematically shown in FIG. 2 for convenience of explanation. Also
Reference numeral 10 is a connection port for connecting an extended air pipe to the proximity position detection nozzle 4 (not shown).

In the position detecting device of the present invention configured as described above,
For example, when a compressed air line having a gauge pressure of 0.3 kg / cm ² is connected to the air source 1, the air inside the chamber passes through the first fixed throttle means 3 and the comparative air passage a and then the nozzle 91 and the flapper surface 93. It is discharged from the gap X.

A positive comparison pressure is generated at the back side of the nozzle 91, that is, at the intermediate position 7 between the nozzle 91 and the first fixed throttle means, corresponding to the size of the gap X between the nozzle 91 and the flapper surface 93 at this time.

On the other hand, also in the proximity position detection nozzle 4 provided at the tip of the extension air pipe connected to the connection port 10, the outflow resistance of the air increases due to the approach of the work W or the like, and the intermediate position of the detection air passage b is the same as above. Positive detection pressure is generated at 6.

The comparison pressure and the detected pressure are respectively the comparison pressure passage c.
And the detection pressure passage d and are guided to the comparison pressure introduction port 81 and the detection pressure introduction port 82 of the differential pressure sensor 8, respectively. Depending on whether the detection pressure is higher or lower than the comparison pressure, the workpiece W is placed on the proximity position detection nozzle 4. A signal indicating whether or not the person is seated is output from the differential pressure sensor 8.

When the rotary dial body 92 is rotated around the rotary shaft 94 with a finger or the like in such an operating state of the position detecting device, the flapper surface 93 formed along the periphery of the rotary dial body 92 and shaped like a spiral. Since the distance from the rotary shaft 94 changes according to the rotational position, the gap X between the nozzle 91 and the flapper surface 93 gradually changes. Therefore, for example, if the tip shape of the nozzle 91 is formed to be the same as the tip shape of the proximity position detection nozzle 4, when the distance of the work W to the proximity position detection nozzle 4 becomes equal to the gap X between the nozzle 91 and the flapper surface 93. It is possible to output the work W detection signal.

Specifically, the metal piece 84 is installed on the diaphragm 83 in the differential pressure sensor chamber 8 and the proximity switch 12 is installed directly above the metal piece 84, and when the detected pressure becomes higher than the comparative pressure, that is, the diaphragm. When the metal piece 84 is pushed up from the bottom and bulges up and the metal piece 84 approaches the proximity switch 12, the lamp of the proximity switch is kept lit.

In this way, in the actual work, when the distance between the proximity position detection nozzle 4 and the work W is 0.05 mm in advance, the flapper surface of the rotary dial body 92 is turned on so that the lamp of the proximity switch 12 is turned on. The gap X between 93 and the nozzle 91 is adjusted and fixed. After this preparation, if work is started and the work W is brought closer to a predetermined position, it can be sensed that the work is accurately seated at the predetermined position when the lamp of the proximity switch is turned on.

By engraving a scale having a value corresponding to the gap X on the rotary dial body 92 and making it visible, it becomes extremely easy to set the working distance as described above, and the rotation angle of the rotary dial body 92 can be adjusted. By setting the change amount of the gap X to be small, it is possible to further improve the setting accuracy of the working distance. Alternatively, it is also possible to perform highly accurate position detection in the vicinity of a plurality of set values.

(Advantages of the Invention) The position detecting device of the present invention is provided with a special variable throttle means having a nozzle and a flapper surface in the comparison air passage in the air bridge circuit so that it can be operated from the outside. Not only can the position detection accuracy be improved, but the detection position can be set very easily, and the high-performance position detecting device can be economically mass-produced.

[Brief description of drawings]

FIG. 1 is a structural diagram of an example of the position detecting device of the present invention, and FIG. 2 is a schematic diagram for explaining the structure and function of the variable diaphragm means. FIG. 3 is a view showing an air bridge circuit in a conventionally known position detecting device, and FIG. 4 is a structural diagram of a needle valve which is a variable throttle means for a conventional air bridge circuit. 1 ... Air source, 2 ... Second fixed throttle means, 3 ... First fixed throttle means, 4 ... Proximity position detection nozzle, 5 ... Variable throttle means, 51 ... Valve body, 52 ... Female thread , 53 ... Needle, 54 ... Male thread, 55 ... Split groove, 8 ... Differential pressure sensor, 81 ... Comparative pressure inlet, 82 ... Detection pressure inlet,
83 …… Diaphragm, 84 …… Metal piece, 9 …… Variable throttle means, 91 …… Nozzle, 92 …… Rotary dial body, 93 …… Flapper surface, 94 …… Rotary shaft, 10 …… Extended air piping connection port , 12
...... Proximity switch, a …… Comparison air passage, b …… Detection air passage, c …… Comparison pressure passage, d …… Detection pressure passage, W
…… Work, X …… Gap.

Claims (1)

[Scope of utility model registration request] 1. A comparison air passage communicating from an air source to the outside of a device via a first fixed throttle means and a variable throttle means, and an outside of the device from the air source to a second fixed throttle means and a proximity position detection nozzle connection port. To the differential pressure sensor from the intermediate position between the first fixed throttle means and the variable throttle means, the second fixed throttle means and the proximity position detection nozzle. The variable throttle means has a nozzle, a flapper surface facing the nozzle, and a scale, the air bridge circuit having a detection pressure passage communicating with a detection pressure introduction port of the differential pressure sensor from an intermediate position with respect to the connection port. And a rotary dial body formed around the nozzle so that the gap between the nozzle and the flapper surface changes according to the rotation angle of the rotary dial body. Exposed outside Position detecting device, characterized in that.