JPS6132614B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixed metal detection device for detecting metal mixed in a fluid. In this specification, the term "fluid" refers to not only a so-called fluid but also an aggregation of powder or granular materials in the form of flakes, chips, or pellets. This also includes cases where metals are mixed in.

Ordinary, powdered milk, tablets, sugar cubes, rubber, lumber,
Metals may be mixed into solid resin raw materials, beverages, etc. in the raw materials or during the manufacturing process in the form of minute metals that are extremely harmful to the human body or small pieces of metal that are extremely dangerous to the human body. In addition, there is a risk that the mixed metal may damage production machines, processing machines, etc. in the next process. For example, if metal is mixed into the solid resin raw material, the mold of the molding machine will be damaged and the product itself will be defective. Therefore, detecting whether such metals are mixed in powdered milk or other fluids is an important step in the production of powdered milk or other fluids. In this type of mixed metal detection device, magnetic flux is passed through the flowing test object, and if metal is mixed in the test object, the presence or absence of mixed metal is detected by changes in the magnetic flux disturbed by the metal. It is already known how to do this. However, in this type of mixed metal detection device, the magnetic flux is not only disturbed by mixed metals, but also by the shaking of external metal objects, resulting in Even though no metal is actually mixed in the fluid, the system malfunctions as if there were mixed metal.

The reason for this is that the primary coil for magnetic flux generation and the secondary coil for detection are provided facing each other across the path of the object to be inspected, so there is metal shielding on the opposing surfaces of both coils. This is because a plate cannot be provided, and as a result, leakage magnetic flux exists in the direction of the inlet and outlet sides of the detector.

The invention aims to eliminate the above-mentioned drawbacks and will be explained in detail below with reference to the illustrated embodiments.

The figure shows a device for detecting metal contaminants in powdered milk, in which 1 is a hopper having a feed conduit 2 made of an insulator. This hopper 1 can be made integrally with the feed conduit section 2 from an insulating material. conduit 2
A mixed metal detector 3 having a primary coil and two secondary coils is provided in the middle. 3A
and 3B are a primary coil cover and a secondary coil cover made of metal, for example, cast metal, and 3C is a cast metal cover that joins both covers 3A and 3B and forms a through hole 3D for the conduit 2 together with both covers. It's a liner. Here, the term "metallic" refers to a material that has conductivity, and includes carbon black, conductive rubber, and the like. Terminal boxes 4 and 5 for connecting the primary coil and secondary coil are provided in recesses 3A' and 3B' provided in the outer walls of the primary coil cover 3A and the secondary coil cover 3B, preferably in a part thereof. be. The primary coil in the cover 3A and the secondary coil in the cover 3B are placed opposite to each other with the conduit 2 in between, and the voltage induced in both secondary coils by the magnetic flux generated from the primary coil. are adjusted by the arrangement of the coils and electrical means so that the outputs are not generated due to conduction cancellation.

The contaminated metal detector 3 is fixed to a base, for example, the floor of the second floor of a building, and the conduit 2 of the hopper 1 passes through the detector 3 and the floor and projects from the ceiling of the first floor. 6 is a feeder that feeds powdered milk to the hopper 1, and the powdered milk is guided to a conduit 2, passes through a detector 3, and is sent to the next process stage on the first floor. If a small metal piece or the like is mixed into the powdered milk passing through the conduit, the balance of the secondary coil is disrupted by the passage of this metal, and a metal detection pulse is generated from the detector 3.

Between the feeder 6 and the detector 3 and between the detector 3 and the next process step, an electromagnetic shielding plate 7 or 8 made of metal, preferably a reverse magnetic material, is arranged so as to cover the detector 3. has been done. In this case, the conduit 2 passes through both shielding plates. These electromagnetic shielding plates 7 and 8 are
It is fixed to the support frame or the detector itself so as not to move relative to the detector 3. The electromagnetic shielding plates 7 and 8 serve to weaken the leakage magnetic flux of the detector 3 to the feeder 6 and hopper 1 or to the next process stage. Therefore, even if the metal feeder 6 vibrates or oscillates in relation to powdered milk feeding, or even if various devices in the next process stage oscillate, the electromagnetic induction between them and the secondary coil of the detector will not occur. They are so small that they can be ignored, and the detector 3 only detects small metal particles in powdered milk. This also applies when the hopper 1 is made of metal.

Thus, according to the present invention, devices having oscillating metal parts, such as belt conveyors, feeders, and other metal parts that accidentally start vibrating, are located relatively close to the detector. However, the effect can be eliminated. Therefore, even in a place where the installation space is relatively small, such as when it is incorporated into existing equipment, it can be installed without being affected by the swinging of external metal parts.

In the embodiment, the electromagnetic shielding plate was provided on both sides of the detector, but if it is far enough away that the swinging external metal part does not affect the electromagnetic shielding plate, the present invention can be applied even if it is provided only on one side of the detector. You can get the initial effect.

[Brief explanation of the drawing]

FIG. 1 is a front view of a mixed metal detection device according to the present invention, and FIG. 2 is a side view thereof. 2...Feeding conduit, 3...Detector, 3A...Primary coil cover, 3B...Secondary coil cover, 3c
... Liner, 3D ... Through hole, 6 ... Feeder, 7, 8 ... Electromagnetic shielding plate.

Claims (1)

[Claims] 1. An insulating feed conduit that guides the fluid; a primary coil for magnetic flux generation and a secondary coil for detection, which are arranged opposite to each other with the conduit sandwiched in the middle of the conduit; the primary coil and a contaminated metal detector comprising a metallic primary coil cover and a metallic secondary coil cover each covering a secondary coil; and a metallic liner joining these coil covers and surrounding the conduit; the contaminated metal detector; A detection device for metal contamination in a fluid, comprising: metal electromagnetic shielding plates spaced apart from the contaminant metal detector above and below in the direction in which the conduit passes through;