JPH04307305A - Non contact dimension measuring instrument - Google Patents

Abstract

PURPOSE:To measure the dimension of an object to be measured in a noncontact state by utilizing the discharge phenomenon of an dark current area. CONSTITUTION:A measurement electrode 9 and object 11 to be measured are moved so that they approach each other while such a low DC voltage that no spark discharge occurs between the electrode 9 and object 11 even when the electrode 9 and object 11 come close to each other is applied across the electrode 9 and object 11 and, when the distance between them reaches a prescribed value, a field emission current flowing between them is detected with a current detector 15. When the current is detected, the further approach of the electrode 9 and object 11 to each other is stopped and the dimension of the object 11 at the stopped position is calculated from the cumulative movement of the object 11. Since the movement is stopped immediately before the electrode 9 comes into contact with the object 11 (when the distance between them becomes 1-2mum), the dimension of the object 11 can be measured with accuracy equivalent to that of a dimension measuring instrument using a touch sensor even though this instrument measures the dimension under such noncontact condition.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact dimension measuring device that measures the dimensions of an object in a non-contact manner by utilizing a discharge phenomenon in a dark current region.

0002

2. Description of the Related Art Measuring devices using touch sensors have been known as devices capable of measuring the dimensions of objects to be measured with high precision. In other words, when the measurement electrode, which is a touch sensor, is gradually brought closer to the object to be measured and the two come into contact, a current flows between the two, and by detecting this current, it is detected that the two have come into contact. Alternatively, a device is known in which the dimensions of the object to be measured are measured from the amount of movement of the measurement electrode up to that point by detecting the contact pressure generated between the two at the time of contact. However, in the case of the above-mentioned measuring devices, since the measurement is performed by bringing the sensor into contact with the surface of the object to be measured, there is a drawback that the measurement device may damage the object to be measured.

On the other hand, measuring devices using optical sensors are known as non-contact dimension measuring devices, and devices that can perform highly accurate measurements have also been developed, but they are very expensive and the devices are complicated. requires special care when handling, etc.
It was not possible to use it easily at the production site.

In addition, as a non-contact dimension measuring device,
Devices using magnetic or electrostatic sensors are also known, but none of them can measure accurately.

[0005]

[Problems to be solved by the invention] As described above, this conventional method uses a non-contact method and can obtain the same level of precision as a dimension measuring device using a touch sensor.The structure is also simple and inexpensive, and it is easy to handle. However, there was no dimension measuring device that could be easily used at production sites.

[0006]

[Means for Solving the Problems] This invention has been made in view of the above points, and its purpose is to prevent two objects from entering the gap between them even when they approach each other. A low DC voltage (50 to 3
00V) is applied and the two objects are gradually moved so that the distance between them becomes closer. When the two objects come close to 1 to 2μ, even if the current is caused by a spark discharge in the gap between them, the current due to the tunneling phenomenon We focused on the fact that a very small current flows, that is, a current due to field radiation, and explained this phenomenon in two ways.
An object of the present invention is to provide a dimension measuring device which can be applied to two objects, a measuring electrode and a measured object, to measure the dimensions of the measured object without the measuring electrode coming into contact with the measured object. .

That is, in order to achieve the above-mentioned object, the present invention is provided such that the measurement electrode and the object to be measured are relatively close to or separated from each other, and the measurement electrode and the object to be measured are provided with a Even when the two approach each other, a low DC voltage that does not cause spark discharge is applied to the gap between them, and the measurement electrode and the object to be measured are moved so that they approach each other relatively. A current detector is provided to detect a current due to field radiation flowing in the gap between the two when the two approaches to a predetermined distance, and when the current is detected by the current detector, the measurement electrode and the object to be measured are The object is stopped from approaching further, and the dimensions of the object to be measured at that point are calculated from the amount of movement up to that point.

[0008]

[Function] With the above structure, when the measurement electrode and the object to be measured are moved relatively close to each other, when the distance between them approaches a predetermined distance (1 to 2μ), the gap between them will be reduced. A current will flow due to electric field radiation. Then, the current detector detects that the current has flowed, so
The measurement electrode and the object to be measured are stopped from coming closer together,
The movement of the measurement electrode is stopped immediately before contacting the object to be measured (at a distance of 1 to 2 μm). In this state, the dimensions of the object to be measured at that location are calculated from the amount of movement up to that point, so that measurement can be performed without bringing the measurement electrode into contact with the object.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an apparatus for measuring the outer diameter of a round-tipped saw will be described below with reference to FIG. Reference numeral 1 denotes a drive device fixed to the base (not shown) of the measuring device, which uses a pulse motor. Reference numeral 2 denotes a moving mechanism consisting of a ball screw, which includes a screw shaft 3 having a spiral groove formed on its outer periphery, and a nut body 4 screwed onto the outer periphery of this screw shaft 3 via a ball (not shown). It is formed. One end of the screw shaft 3 is connected to the rotating shaft of a pulse motor 1, which is a driving device, via a coupling 5, and when the screw shaft 3 is rotated by the rotation of the pulse motor 1,
The nut body 4 is moved along the screw shaft 3, but in this case the nut body 4 itself is moved without rotating. 6 is an arm protruding from the nut body 4, 7 is an arm 5
By fixing the proximal end to the tip of the support rod, the support rod is provided along the screw shaft 3 so as to be parallel to the screw shaft 3, and the measuring electrode 9 is attached to the distal end via the insulator 8. By moving the nut body 4 along the screw shaft 3, it moves forward and backward relative to the object to be measured 11, which will be described later.

10 is a round tipped saw 11 which is an object to be measured.
A support shaft for attaching the measuring electrode 9, which is provided on the base of the measuring device so as to be located on the moving direction of the measuring electrode 9.
Moreover, it is configured to rotate by a predetermined angle by a rotation mechanism (not shown).

Reference numeral 12 denotes a DC power supply whose output voltage can be adjusted in the range of 50 to 300V, the cathode of which is connected to the measuring electrode 9 through a current limiting resistor 13, and the anode connected to a round chip saw through a current detecting resistor 14. It is connected to the 11 side. 15 is a current detector connected to both ends of the current detection resistor 14; 16 is rotation stop command means for instructing the pulse motor 1 to stop its rotation when the current detector 15 detects a current; 17 is a rotation stop command means This calculation means is configured to calculate the outer diameter dimension of the round tipped saw 11 at that point from the amount of forward movement of the measurement electrode 9 by stopping its forward movement.

Next, a case will be described in which the radius of the teeth of a round-tipped saw is measured using the above-mentioned measuring device. After attaching the round tipped saw 11 to be measured to the support shaft 10, the pulse motor 1 is rotated in the forward direction to rotate the screw shaft 3. Then, the nut body 4 moves along the screw shaft 3, and the measuring electrode 9 gradually moves forward in the direction of the tipped saw 11. In that case, at first, there is a considerable distance between the tip of the measuring electrode 9 and the outer periphery of the tipped saw 11, so no current flows between the measuring electrode 9 and the tipped saw 11, but as the distance gradually narrows and they get close to 1 to 2μ, , a current flows through the gap between the two due to field radiation. That is, from the anode of the DC power supply 12, the current detection resistor 14, the chip saw 11,
Since a current due to field radiation flows through the measurement electrode 9 and the current limiting resistor 13 to the cathode of the DC power supply 12, a voltage drop occurs across the current detection resistor 14, and the current flow is detected by the current detector 15. detected by.

When it is detected that a current has flowed, the rotation stop command means 16 instructs the pulse motor 1 to stop its rotation, so that the rotation of the pulse motor 1 is stopped and the measurement is performed. The forward movement of the electrode 9 is stopped immediately before it comes into contact with the chip saw 11. When the forward movement of the measuring electrode 9 is stopped, the radius of the tooth portion of the tipped saw 11 at that point is calculated by the calculation means 17 from the amount of forward movement up to that point. That is, the position of the tip of the first measuring electrode 9 and the support shaft 10 to which the chip saw 11 is attached.
If the distance between the center of -B
-C (where C is the gap between the tip of the measuring electrode 9 and the outer periphery of the teeth of the tipped saw 11 when the forward movement is stopped). The calculation results obtained in this manner are preferably recorded on a separately prepared recording device. The distance A is preferably set in advance, and the distance B is preferably determined from the number of pulses supplied to the pulse motor 1.

After measuring the radius X of one tooth of the chip saw 11 in this way, the pulse motor 1 is rotated in the opposite direction to move the measuring electrode 9 back to its original position, and at the same time, the support shaft 10 is moved back. Rotate the teeth of the chip saw 11 by one pitch. Thereafter, the radius X of the entire tooth portion is measured by repeating the above-described operation.

In the above, the relationship between the voltage of the DC power supply 12 and the gap where the current starts flowing due to field radiation is as shown in FIG. 2. For example, when the voltage of the DC power supply 12 is set to 300V, the current limiting resistor 13 is Current detection resistor 1
4 is set to 100KΩ, when the tip of the measurement electrode 9 and the outer periphery of the tipped saw 11 come close to 2μ, a current will flow through the gap between the two due to field radiation. By the way, if you set the voltage of DC power supply 12 to 350V or higher,
As is clear from Paschen's law shown in Figure 3, 1
Spark discharge occurs at a gap of around 0μ, and the gap at which the discharge starts becomes extremely unstable.

[0016] In the above description, the case has been described in which the apparatus is used as an outside diameter measuring device for a round tipped saw 11, so the round tipped saw 11, which is the object to be measured, is attached to the support shaft 10 for measurement. The structure of the attachment portion for attaching the object to be measured may be formed into an appropriate structure depending on the shape of the object to be measured.

[0017]

[Effects of the Invention] As explained above, the present invention applies a low DC voltage to the measurement electrode and the object to be measured, which does not cause spark discharge in the gap between the two even when the two come close to each other. In addition, when the measurement electrode and the object to be measured are moved relatively close to each other and the distance between the two approaches a predetermined distance, a current detector is installed to detect the current due to the field emission flowing in the gap between the two. and when the current is detected by this current detector, the measurement electrode and the object to be measured are stopped from coming closer to each other, so that the measurement electrode is stopped from coming closer to the object to be measured (1 to 2μ). separated state)
Since the movement is stopped at , it is possible to provide a dimension measuring device that can measure with the same accuracy as a dimension measuring device using a touch sensor, although it is a non-contact type.

Furthermore, when the measurement electrode and the object to be measured are brought close to each other, the electric current caused by the field radiation flowing in the gap between them is a very small current. This allows measurements to be taken without creating chips or scratches on the object being measured, and can therefore be used for dimension and angle measurements of saw teeth and carbide tools, as well as measurements of materials with high resistivity such as cermets and semiconductors. This means that it is possible to provide a dimension measuring device that can also be used for measurements.

[0019] Since it can be implemented with a relatively simple configuration, it can be manufactured at low cost and can be used without requiring special care when handling, so it is possible to provide a dimension measuring device that can be easily used at production sites.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a part of the present invention applied to an outer diameter measuring device for a round-tipped saw as an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the voltage applied between the measurement electrode and the object to be measured and the gap at which a current starts flowing due to a radiated electric field.

FIG. 3 is a diagram showing Paschen's law.

[Explanation of symbols]

1 Drive device 2　Movement mechanism 9 Measurement electrode 11 Object to be measured 12 DC power supply 15 Current detector 16 Rotation stop command means 17 Calculation means

Claims (1)

[Claims] Claim 1: The measurement electrode and the object to be measured are provided so that they approach or separate from each other, and even when the measurement electrode and the object to be measured approach each other, there is no gap between the two. A low DC voltage that does not cause spark discharge is applied to the electrode, and when the measurement electrode and the object to be measured are moved relatively close to each other and the distance between them approaches a predetermined distance, A current detector is provided to detect a current due to field emission flowing in the gap between the two, and when the current is detected by the current detector, the measurement electrode and the object to be measured are stopped from coming closer to each other, A non-contact dimension measuring device that calculates the dimensions of the object to be measured at that point based on the amount of movement up to that point.