JPH08278370A - Detection head of metal detection device - Google Patents

Abstract

PURPOSE: To guide and position a coil frame into a center in a case by forming a guide/position part on the inner wall of a metal case and fixing the coil frame perpendicular to the passing direction of an inspection object, in the metal case. CONSTITUTION: In a metal case 7 with the side having an opening upward, a coil frame 4 is contained with its side face 4e downward at about center of the case 7 along a guide positioning part 12 provided on the inner wall of the case. A gap between the frame 4 and the inner wall of case 7 is moved in the passage direction of an inspection object for positioning so that induction voltages of both reception coils 3a and 3b are equal, and then fixed with a fixing screw 10. Then the gaps between two square holes of the case 7 and the end faces 4a and 4b of the frame 4 are stopped and filled up with a filler 11 from above, for soldification. By this, a detection head 1 is easily positioned, and manufactured in short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection head of a metal detection device.

[0002]

2. Description of the Related Art Conventionally, a detection head of this type of metal detection device is usually housed in a metal case made of a metal material, and the main part of the detection head is constructed, for example, as follows.
There is one shown in FIG. In FIG. 1, the detection head 100 includes a transmission coil 101 for generating a magnetic flux,
Two receiving coils 1 arranged so as to interlink with the magnetic flux
02 and 103, and an object to be inspected 104 which is a target of detection of mixed metal, is provided with the sending and receiving coils 101, 102,
A passage 106 passing through the inspection space 105 inside 103 is passed in the direction of the arrow.

The transmitting coil 101 is excited by a high frequency generator (not shown) to generate high frequency magnetic flux. The two receiving coils 102 and 103 are arranged so that a part of this magnetic flux is linked in an equal amount. Then, one ends of the two receiving coils 102 and 103 have opposite polarities,
That is, they are differentially connected and each output signal V1,
Due to the difference in V2, the transmitting and receiving coils 101, 102,
The inspection object 10 passing through the inspection space 105 inside 103
The metal mixed in 4 is detected.

By the way, this detection head 100 is shown in FIG.
As shown in FIG. 3, after the sending and receiving coils 101, 102, 103 are wound around the outer circumference of the coil frame 107 made of an insulator, the coil frame 107 is closed by the metal case 108 shown in FIG.
Is disposed inside. At the edges of the rectangular through holes 108a and 108b provided in the front-rear direction of the metal case 108, as shown in the central transverse sectional view of FIG.
A plurality of screw holes 109 are provided so as to penetrate from the outside to the inside of 08, and a fixing screw 110 is screwed into each of the screw holes 109. The fixing screw 110 positions the coil frame 107 so that the output signals from the two receiving coils 102 and 103 become equal from the front-back direction in which the DUT 104 passes, and then, the metal case. It is disclosed that the space between 108 and the coil frame 107 is filled with an epoxy (or unsaturated polyester) filler 111. (Actual Kaihei
No. 5-28984)

[0005]

However, in order to equalize the induced voltage difference between the receiving coils 102 and 103 in order to maintain magnetic balance, the position of the coil frame 107 is fixed from both sides of the metal case 108 by the fixing screws 110. It was very difficult to position the movable coils by moving any of the fixing screws 110 to generate the induced voltage difference between the receiving coils 102 and 103 and to determine the positions where the induced voltages are equal. Further, this work requires skill, but it took much time even after the skill. An object of the present invention is to provide a detection head for a metal detection device that solves this problem.

[0006]

In order to solve the above-mentioned problems, positioning and fixing are not performed by a fixing screw in the passing direction of an object to be inspected whose balance adjustment is difficult, but the coil frame is preliminarily set in the metal case in advance. In order to guide and position in the center, a guide positioning portion was formed on the inner wall of the metal case, and the coil frame was fixed to the metal case perpendicularly to the passing direction of the object to be inspected by fixing means.

[0007]

Since the present invention is constructed as described above, the coil frame can be guided and positioned substantially in the center of the metal case. In addition, in the passing direction of the inspection object,
There is no slippage when fixed.

[0008]

FIG. 5 is a sectional view taken along the line AA 'in FIG. 6, showing a main part of a detection head 1 of one embodiment, FIG. 6 is a perspective view of the detection head 1 of one embodiment, and FIG. FIG. 7 is a front view of the detection head 1 of one embodiment, and FIG. 7 is a perspective view showing the configuration of the coil frame 4 of one embodiment.

The detection head 1 is of the above-mentioned coaxial type and has a pair of receiving coils 3a, 3 which are magnetic sensors thereof.
As shown in FIG. 7, b is wound around the outer periphery of the coil frame 4 together with the transmission coil 2 at the same intervals. The coil frame 4 is made of a baking material or the like so as to form a rectangular parallelepiped inspection space 5 inside the transmitting coil 2 and the receiving coils 3a and 3b. This coil frame 4 has its front end face 4
The a and the rear end surface 4b are housed along the guide positioning portion 12 provided on the inner wall of the metal case 6 made of an aluminum material and with a slight gap in the passage direction of the inspection object.

The metal case 6 is composed of a metal case body 7 formed of an aluminum material on a substantially rectangular parallelepiped, and an outer lid 8 for sealing one open side surface of the metal case body 7. Square holes 7a and 7b having a size continuous with the inspection space 5 inside the coil frame 4 are provided on the front surface and the rear surface of the metal case body 7.

A plurality of screw holes 9 for fixing the coil frame 4 are provided at the edges of the square holes 7a and 7b.
A fixing screw 10 formed of a non-magnetic material such as plastic is fitted in the. These screw holes 9 and fixing screws 1
Reference numeral 0 denotes an object that realizes the contents of the present invention, and the fixing screw 10 fixes the metal case body 7 and the coil frame 4 at predetermined positions.

The positioning of the coil frame 4 and the metal case body 7 is already supported by the guide positioning portion 12,
And since it is already guided to the center, the filler 1
Before being filled with 1, it is easily positioned at a position where the induced voltage difference between the receiving coils 3a and 3b becomes equal, and fixed by the fixing screw 10. Further, since the fixing direction of the fixing screw 10 is changed to the up-down direction, not the front-rear direction in which the object to be inspected of the metal case body 7 passes, the positioning can be performed without being misaligned during the fixing after the positioning. . Further, the inner wall 7c of the metal case body 7 and the upper surface 4c, the lower surface 4d and the side surfaces 4e, 4f of the coil frame 4 are firmly fixed by a resin-based filler 11.

Next, a method of assembling the detection head 1 will be described. First, the coil frame 4 is housed in the metal case body 7 with the opened side surface facing upward by the guide positioning portion 12 so that the coil frame 4 has one side surface 4e facing downward. Then, the gap between the coil frame 4 and the inner wall of the metal case is moved in the passing direction of the object to be inspected,
After positioning the receiving coils 3a and 3b at positions where the induced voltages are equal to each other, they are fixed by the fixing screw 10. After this positioning and fixing, the gap between the square holes 7a and 7b and the front end surface 4a and the rear end surface 4b of the coil frame 4 is closed, and the filler 11 is injected from above. The injected filling material 11 is filled between the outer periphery of the coil frame 4 and the inner wall of the metal case body 7,
It hardens completely after a predetermined time.

During this hardening, the coil frame 4 is fixed to the fixing screw 10.
Since it is completely fixed by, the positional deviation of the coil frame 4 due to the thermal contraction of the filling material 11 does not occur, and as a result, the magnetic balance deviation hardly occurs. For this reason,
The induced voltages of both receiving coils 3a and 3b can be perfectly balanced by only electrical adjustment of a balance volume or the like. After the filling material 11 is completely hardened, the outer lid 8 is attached to the metal case body 7, and the assembling work is completed.

[0015]

As described above, since the detection head of the metal detection device of the present invention can be easily positioned and the magnetic balance does not shift when it is fixed after the positioning, no skill is required and a short time is required. Can be created.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a detection principle of a coaxial type detection head of a detection head of a conventional metal detection device.

FIG. 2 is a diagram showing a main configuration of the detection head of FIG.

FIG. 3 is a perspective view showing a detection head of a conventional metal detection device.

FIG. 4 is a cross-sectional view of the central portion of FIG.

5 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 6 is a perspective view of a detection head of one embodiment.

FIG. 7 is a configuration of a coil frame according to an embodiment.

FIG. 8 is a front view of the detection head according to the embodiment.

[Explanation of symbols]

 1 detection head 2 transmission coil 3a, 3b reception coil 4 coil frame 4a front end surface 4b rear end surface 4c upper surface 4d lower surface 4e, 4f side surface 5 inspection space 6 metal case 7 metal case body 7a, 7b square hole 8 outer lid 9 screw hole 10 Fixing screw 11 Filling material 12 Guide positioning part 104 Inspected body

Claims (1)

[Claims] 1. A magnetic signal is housed in a metal case to excite a transmitter coil to generate a magnetic flux, and a difference signal output from two receiver coils interlinking with the magnetic flux is used to detect the inside of the transmitter and receiver coils. In a detection head of a metal detection device for detecting a metal mixed in an object to be inspected passing through an inspection space, a coil frame made of an insulator is provided between the transmitting coil and each of the two receiving coils. Guide and position on the inner wall of the metal case in order to rotate the sending and receiving coils at equal intervals in the front-rear direction along the axis of the frame to guide and position the coil frame in the approximate center of the metal case. And a coil frame fixed to the metal case by a fixing means perpendicular to the passing direction of the object to be inspected.