JPS6236150Y2 - - Google Patents

Description

[Detailed description of the invention] The invention relates to a metal detection element, and more specifically, an oscillation circuit is connected to an electromagnet with a wire wound around a pot core, and a metal piece is detected in the alternating magnetic field generated by the electromagnet. The passage of a metal piece is detected by utilizing the fact that the voltage of the oscillation circuit is attenuated by the eddy current generated in the coil when a metal piece passes through the coil, or the passage of a metal piece is detected at a predetermined distance from the detection end. The present invention relates to a metal detection element that detects whether or not a metal piece has approached within a range of 200 degrees, and that is capable of detecting a metal piece that has passed or approached from two directions.

In recent years, as automated machine tools such as NC machine tools have come into widespread use, various detection elements have become necessary to automate processes such as centering the installation of workpieces on machine tools and inspecting finished dimensions. ing. In addition, in vending machines and the like, there is a demand for small and accurate sensing elements for detecting, classifying, and calculating the quantity of metals. Furthermore, in addition to these, the detection element that detects a metal piece or detects whether a metal piece approaches within a predetermined distance from the detection end face can be used to classify metal pieces, calculate quantity, automatically manage inventory, etc. It has many uses.

There are a number of metal detection elements that utilize the principle of the so-called inductive proximity switch, which attenuates the voltage of the oscillation circuit when a metal is present within the alternating magnetic field generated by the electromagnet, thereby emitting a detection signal. It has the following characteristics and is extremely excellent.

(1) It is possible to detect metal pieces passing at high speed.

(2) It has extremely high processing capacity.

(3) High dimensional accuracy can be obtained.

(4) Since there is no part that comes into contact with the metal piece being detected, there is no wear, there are few failures, and the product has a long life, even though it can detect metal pieces passing at high speed with extremely high throughput.

(5) Detection accuracy is not affected by vibrations, temperature changes, dust, air pollution, etc.

Conventionally, detection elements that utilize the principle of this inductive proximity switch are often used in industrial applications such as machine tools, and there are no compact and lightweight devices, such as vending machines and other devices that require miniaturization. It was unsuitable for me.

Furthermore, conventionally, this sensing element has been used as shown in FIG. In other words, a detection element B attached to a reference surface A (for example, the bed surface of a machine tool) detects a metal piece that passes between or is close to a surface D that is a predetermined distance from the end surface C. Although it is becoming more and more
As is obvious from the figure, detection of passage is limited to the direction of the arrow X-X, and the direction of _Y1 - _Y1 perpendicular to this is the
can't be detected because it gets in the way. Furthermore, detection in the Y ₂ -Y ₂ direction that avoids element B is uncertain. Furthermore, the proximity is limited to the _Y1 - _Y1 direction, and the accuracy of the predetermined distance from the X-X direction is extremely poor and cannot be put to practical use.

The present invention eliminates the above-mentioned drawbacks of conventional metal detection elements at once, and is a metal detection element that uses the principle of a small, lightweight, and reliable inductive proximity switch. It is an object of the present invention to provide a metal detection element capable of detecting passage or proximity.

The present invention is based on the fact that an electromagnet consisting of a coil wound around a so-called pot core made of a magnetic material such as ferrite has a shape that is extremely suitable for generating an effective leakage magnetic field, and that an alternating magnetic field is applied to this electromagnet. It was developed based on the fact that printed wiring circuits or integrated circuits incorporating a detection circuit, a power supply circuit, a display circuit, etc. in addition to the oscillation circuit that generates the oscillation circuit can be easily and inexpensively obtained. A housing is installed outside the housing, and an oscillation circuit, a detection circuit, a display circuit,
The above object is achieved by incorporating a power supply circuit, etc., and by cutting the open end of the pot core in a plane obliquely intersecting the axis of the pot core.

Embodiments of the present invention will be described below based on the drawings. Fig. 2 is a view of the metal detection element B according to the present invention viewed from the direction of its detection surface C, Fig. 3 is a view of the - cross section in Fig. 2 viewed in the direction of the arrow, and Fig. 4 is a view of the - cross section in the same direction. This is a diagram viewed in the direction of the arrow, with some parts omitted. In FIGS. 2 to 4, the metal detection element B consists of an electromagnet 1, a housing 11 provided adjacent to the electromagnet 1, a circuit 21 housed within the housing 11, and the like.

The electromagnet 1 consists of a pot core 2 and a coil 3 having a wire wound around the core 2. pot core 2
is integrally molded from magnetic material such as ferrite,
A large cylinder 2a and a small cylinder or small cylinder (the illustrated example is a small cylinder) 2b are arranged coaxially, one end surface of which is connected by a disk 2C having a surface perpendicular to the axis, and the disk 2C and The opposite end surface is shaped to form part of a plane obliquely intersecting the axis.

The coil 3 is inserted into an annular space formed by both cylinders. The end surface of the pot core 2 opposite to the disk 2a is protected by a non-magnetic thin plate 4 made of resin or the like, and this surface serves as a detection surface C.

The housing 11 has a cylindrical shape whose outer surface is covered with a metal plate 12, and the pot core 2 is inserted into one end thereof with the disk 2C facing inside.

A circuit 21 is housed within the housing 11. The circuit 21 includes a printed circuit board 22, various parts 23 attached to the circuit board 22, and the printed circuit board 2.
2, a coil 3, and wiring interconnecting lead wires 24. In addition, the circuit 21 includes an oscillation circuit that generates an alternating magnetic field in the electromagnet, a detection circuit that detects whether or not a metal piece is present in the magnetic field, and a display circuit that displays the detected results. It consists of a power supply circuit for supplying electric power.

A seal portion 13 is attached to the other end of the housing 11 , and a lead wire 24 is inserted through the center of the seal portion 13 .
A sealing material 14 is fitted between the two. A display board 15 using a light emitting diode may be attached to the outside of the housing 11 if necessary.

FIG. 5 shows an example of a method for attaching the metal detection element according to the present invention as exemplified above. In other words, if sensing element B is attached to reference surface A (for example, the bed surface of a machine tool), surface D will be formed at a predetermined distance from sensing surface C, and if there is metal between surfaces C and D, detected. In this case, as is clear from the figure, metal pieces passing along the axis X ₂ -X ₂ are detected, and also those passing along the axis Y ₂ -Y ₂ are accurately detected. Furthermore, the axis X ₁ −X ₁
, along the axis Y ₁ −Y ₁ is detected accurately at a given distance. That is, it is possible to detect objects from two directions, both passing and approaching.

Furthermore, since the metal detection element according to the present invention exemplified above utilizes the principle of an inductive proximity switch as is self-evident, it has the features shown in (1) to (5) above, and is extremely excellent. In addition to having detection performance, it uses a pot core made of a magnetic material such as ferrite as the magnetic core of the electromagnet, and further uses a printed circuit board as the circuit, so it can be made extremely small and lightweight. Furthermore, since the detection surface is inclined with respect to the axis of the core and housing that constitute the element, it is possible to detect a metal piece passing through or approaching from two directions. It is possible. Needless to say, it is possible to further reduce the size and weight by using an integrated circuit instead of the printed circuit board described above. Moreover, this printed circuit board or integrated circuit is relatively easy to obtain and inexpensive.

As described above, the present invention provides a metal detection element that is small and has extremely excellent detection performance.
It is clear that this will greatly contribute to improving the performance and reducing costs of automatic machine tools, vending machines, and other automatic mechanical devices.

[Brief explanation of the drawing]

Figure 1 is a diagram showing how to use a conventional sensing element;
FIG. 2 is a view of the metal detection element according to the present invention viewed from its detection surface, FIGS. 3 and 4 are views of the - cross section and - cross section of FIG. The figure shows how to install it. A... Reference surface, B... Sensing element, C... Detecting surface, D... Surface, 1... Electromagnetic, 2... Pot core,
2a...Large cylinder, 2b...Small cylinder, 2c...Disk, 3...Coil, 4...Thin plate, 11...Housing, 12...Metal plate, 13...Seal portion, 14
... sealing material, 15 ... display board, 21 ... circuit,
22...Printed circuit board, 23...Parts, 24...
Lead.

Claims (1)

[Scope of utility model registration request] A large cylinder and a small cylinder coaxially formed integrally from a magnetic material, or one end face of the small cylinder is connected by a disk having a surface perpendicular to the axis, and the other end face is oblique to the axis. An electromagnet formed by winding a winding around a pot core having a shape that looks like a part of a plane, and a housing provided outside the disk of the core and containing an oscillation circuit, a detection circuit, a display circuit, and a power supply circuit. A metal detection element equipped with