JPH08219132A - Attitude discriminating device of fastening member - Google Patents

Abstract

PURPOSE: To assuredly and automatically discriminate between normal and reverse directions of the holding attitude of a bolt without depending on the condition of a bolt surface. CONSTITUTION: A displacement sensor 2 is provided on the outer circumferential surface of a cylindrical holding part 1, and oppositely arranged to the straight part 4 of a stud bolt 3 held toward one of normal and reverse directions by the holding part 1. The displacement sensor 2 is a magnetic induction sensor having energizing means which applies high frequency magnetic field to a body to be detected and generates eddy current on the surface of the body to be detected by electromagnetic induction and detecting means which indirectly detects the strength of the eddy current and converts the eddy current into an electric signal so as to obtain sensor output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for automatically discriminating the holding posture of a fastening member having a screw portion and a straight portion, for example, a stud bolt.

[0002]

2. Description of the Related Art A stud bolt having a threaded portion on both sides of a smooth straight portion has axial directionality.
Therefore, when the stud bolt is allowed to freely fall from the downstream end of the parts feeder or the like and is held by an appropriate holding device, the holding posture of the bolt varies in the forward and reverse directions.

By the way, if such a variation in the holding posture is left as it is, the work in the next step is hindered. Therefore, after holding the bolt by the holding device, it is determined whether the holding posture of the bolt is normal or reverse, and the information is transmitted to the next process to change the working posture according to the posture of each bolt, or It is necessary to align the bolts in the normal direction based on

Conventionally, in view of such a request for posture determination, a laser sensor or a reflection type photoelectric switch having a small spot diameter is provided on the outer peripheral side of the bolt in the holding device as shown in FIG. It is arranged diagonally with respect to the axis of the bolt, and the bolt (1
0) posture is determined. In other words, since the inspection light is reflected as it is at the straight portion (11), the reflected inspection light does not enter the sensor (12) and the like, but at the screw portion (13), one portion of the inspection light reflected by the screw threads is reflected. The bolt (10) is utilized by the fact that the part enters the sensor (12) etc.
The forward and reverse of the posture of is determined.

[0005]

However, with such an optical means, the intensity of the reflected light depends on the presence or absence of scratches or stains on the bolt surface, so that it is difficult to make a highly accurate determination. It was

Therefore, an object of the present invention is to provide a device capable of accurately determining the posture of the bolt without being influenced by the state of the surface of the bolt.

[0007]

To achieve the above object, the device of the present invention is a device for discriminating the holding posture of a fastening member having a screw portion and a smooth straight portion. A holding part for holding in an arbitrary direction, and an eddy current type displacement sensor arranged at a position facing the straight part of the fastening member when held by the holding part in either one of the forward and reverse directions. There is.

A device for determining the holding posture of a fastening member having a screw portion and a smooth straight portion, the holding member holding the fastening member in any forward and reverse directions, and the fastening member by the holding portion. Regardless of whether it is held in any of the normal and reverse directions, the first and second displacement sensors of the eddy current type are provided such that one of them is always arranged to face the straight portion.

[0009]

When the holding member holds the fastening member, the displacement sensor faces either the straight portion or the screw portion of the fastening member. When an eddy current is induced in the facing portion by the displacement sensor, the eddy current easily flows in the straight portion, but the eddy current does not easily flow in the screw portion due to the presence of the screw thread. This is because the eddy current flows near the surface of the detected object. Therefore, if the displacement sensor detects the intensity of the eddy current and outputs this as a sensor output, a difference occurs in the output value between the screw portion and the straight portion. From the above points, if the output value of the displacement sensor is compared with a preset reference value after the fastening member is held by the holding portion, it is determined whether the position opposite to the displacement sensor is the screw portion or the straight portion. ,In other words,
It is possible to determine whether the fastening member is in the normal posture or the inverted posture.

Further, no matter whether the fastening member is held by the holding portion in any of the forward and reverse directions, if the eddy current type first and second displacement sensors are arranged at positions where one of them is always opposed to the straight portion. When the holding member holds the fastening member, one of the first and second displacement sensors faces the straight portion and the other sensor faces the screw portion. Therefore, it is possible to determine the positional relationship between the straight portion and the screw portion, that is, whether the posture of the fastening member is normal or reverse only by comparing the output values of the both sensors.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1 and FIG. 2, the device of the present invention is a thick-walled cylindrical holding portion (a stud bolt: hereinafter simply referred to as "bolt") for holding a fastening member (3) at a fixed position. 1) and a displacement sensor (2) mounted on the outer peripheral surface of the holding portion (1).

The bolt (3) has a smooth straight portion (4) which is unevenly distributed from the central portion to one end side, and the threaded portion is formed on both sides of the straight portion (4). (5) is provided. The outer diameter of the straight portion (4) and the maximum diameter of the screw portion (5) are the same.

The holding hole (6) penetratingly formed in the central portion of the holding portion (1) has the same diameter as the maximum diameter of the bolt (3) or a diameter slightly larger than this. The shape and structure of the holding portion (1) are not limited to the cylindrical shape as shown in the drawing, and are arbitrary as long as the bolt (3) can be held at a fixed position.

The displacement sensor (2) has a through hole (7) provided at one location on the side wall of the holding portion (1), and its detection portion (8) is made to coincide with the inner diameter surface of the hole or from the inner diameter surface. It is inserted slightly backward. This displacement sensor (2)
As shown in FIG. 3A, the holding hole (6) of the holding portion (1)
When the bolt (3) is inserted in either one of the normal and reverse postures, for example, the regular posture, the detection portion (8) is provided at a position facing the straight portion (4). In this case, when the bolt (3) is inserted into the holding hole (6) in the other posture, for example, in the inverted posture, as shown in FIG. 7B, the detection unit (8) faces the screw portion (5). .

An eddy current type proximity switch is used as the displacement sensor (2). Specifically,

Exciting means (coil) that applies a high-frequency magnetic field to the object to be detected to generate an eddy current on its surface by electromagnetic induction; The strength of this eddy current is indirectly detected, and this is converted into an electric signal to be a sensor. Detection means for obtaining output;

A magnetic induction type sensor having is used.
As a method of detecting the eddy current, there are a method of detecting an impedance change of the exciting means and a method of detecting a voltage change induced in a coil provided separately from the exciting means. Specific examples of the former include a method in which an oscillation circuit is connected to the coil to detect the oscillation frequency and the oscillation amplitude, or an induction bridge circuit. The latter includes a differential coil.

In the structure described above, when the bolt (3) is inserted into the holding hole (6) of the holding portion (1) in either forward or reverse direction, the detecting portion (8) of the displacement sensor (2) causes the bolt (3) to move. ), Either the straight portion (4) or the screw portion (5). When a high-frequency magnetic field is applied by the exciting means of the displacement sensor (2) to induce an eddy current in the portion of the surface of the bolt (3) facing the detection portion (8), the eddy current easily flows in the straight portion (4), The presence of the thread makes it difficult for eddy currents to flow in the screw portion (5). This is because the eddy current flows near the surface of the detected object. The strength of this eddy current is indirectly detected by utilizing the impedance change of the coil, and when this is output as a sensor output, the straight portion (4)
And the screw part (5) causes a difference in sensor output.

From the above points, after holding the bolt (3) by the holding portion (1) and comparing the output value of the displacement sensor (2) with a preset reference value, the opposing position of the displacement sensor (2) It is possible to determine whether there is a screw portion (5) or a straight portion (4) in other words, in other words, whether the fastening member is in the normal posture or the inverted posture. As shown in FIG. 4, the reference value is obtained by obtaining the normal distribution of the sensor output for each of the straight portion (4) and the screw portion (5), and then determining the minimum distribution (for example, the screw portion) on the side with the larger output value. It is set in a region t between the value and the maximum value of the distribution (for example, the straight portion) on the smaller output value side.

FIG. 5 shows another embodiment of the present invention. This is one in which two displacement sensors (2a) and (2b) are arranged in the holding portion (1) so as to be separated from each other in the axial direction. The first displacement sensor (2a) is similar to the device of FIG. The second displacement sensor (2b) is arranged in a position facing the straight portion (4) of the bolt (3) held in one of the postures (regular posture), and the second displacement sensor (2b) is held in the other posture (reversed posture). The bolt (3) is arranged at a position facing the straight portion (4). Both displacement sensors (2a) and (2b) have the same structure and function as the displacement sensor (2) used in the device shown in FIG.

According to this structure, even when the bolt (3) is held in the normal posture (FIG. 6 (a)) or in the inverted posture (FIG. 6 (b)), one sensor (2a) must be held.
(2b) faces the straight portion (4), and the other sensor (2b) (2a) faces the screw portion (5). Therefore, the positional relationship between the straight portion (4) and the screw portion (5), that is, the holding posture of the bolt (3) can be determined only by comparing the output values of both sensors (2a) and (2b). It becomes possible to do. In this case, it is possible to save the labor of obtaining the reference value and comparing the reference value with the detected value, so that the work can be simplified as compared with the apparatus shown in FIG.

In the above description, the case where the stud bolt is used as an object to be discriminated is illustrated, but the present invention is not limited to this, and the screw portion (5) and the smooth straight portion (4) are used. It is applicable to the attitude determination of all fastening members having

[0024]

As described above, according to the present invention, the fastening member having the screw portion and the smooth straight portion is held in the holding portion in the normal holding posture, or is held in the 180 ° inverted posture. It is possible to easily and accurately discriminate whether or not it has been done. In addition, since the eddy current flowing on the surface of the detected object is used for the attitude determination, the attitude can be determined without being affected by scratches or dirt on the surface of the detected portion. Further, since the eddy current type displacement sensor is cheaper than the laser sensor, the manufacturing cost can be reduced.

No matter which direction the fastening member is held by the holding portion, the eddy current type first and second displacement sensors are arranged at positions where one of them always faces the straight portion. Only by comparing the output values of the sensors, it becomes possible to determine the positional relationship between the straight portion and the screw portion, that is, the forward / reverse of the posture of the fastening member. In this case, it is possible to omit the work of obtaining the reference value and comparing it with the detected value, and therefore the work can be simplified.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a device of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA in FIG.

FIG. 3A is a vertical cross-sectional view when the bolt is held in a normal posture, and FIG. 3B is a vertical cross-sectional view when the bolt is held in an inverted posture.

FIG. 4 is a diagram showing a distribution of sensor output.

FIG. 5 is a vertical sectional view showing another embodiment of the device of the present invention.

6A is a vertical cross-sectional view when the bolt is held in a normal posture, and FIG. 6B is a vertical cross-sectional view when the bolt is held in an inverted posture.

FIG. 7 is a side view of a conventional device.

[Explanation of symbols]

 1 Holding Part 2 Displacement Sensor 2a First Displacement Sensor 2b Second Displacement Sensor 3 Fastening Member (Stud Bolt) 4 Straight Part 5 Screw Part 8 Detection Part

Claims (2)

[Claims] 1. A device for discriminating a holding posture of a fastening member having a screw portion and a smooth straight portion, the holding portion holding the fastening member in a normal direction and a reverse direction by the holding portion. An eddy current type displacement sensor arranged at a position facing a straight portion of the fastening member when held in one of the orientations. 2. A device for determining a holding posture of a fastening member having a screw portion and a smooth straight portion, the holding portion holding the fastening member in any forward and reverse directions, and the fastening member by the holding portion. The fastening member is characterized by including an eddy current type first and second displacement sensor, which is always arranged at a position facing the straight portion regardless of whether it is held in any direction. Attitude determination device.