JPS5924069B2 - lifting electromagnet - Google Patents

Description

[Detailed description of the invention] This invention is suitable for selectively suspending steel materials, especially steel plates.

Concerning suspended electromagnets. In general, in a lifting electromagnet intended for lifting a large number of steel plates, the ability to lift a large number of steel plates is ensured and improved by increasing the area of its attracting poles or by increasing the size of the electromagnet itself to increase its capacity. The main focus was on

Therefore, although it is extremely effective for lifting and conveying a large number of steel plates or for thick steel plates, on the other hand, the characteristics of lifting and selecting the number of sheets to be lifted for thin steel plates are extremely poor. In other words, there was a drawback that it became difficult to easily select and adsorb the desired number of steel plates. To further explain this, using the conventional electromagnet for lifting a large number of steel plates shown in Figs. made of materials.

Reference numeral 2 denotes an excitation coil which is connected to a DC power source and whose magnetic force is adjusted by voltage or current control.

3 is a group of steel plates to be lifted.

In a state where the passage area of the magnetic flux φ flowing through the steel plate group 3 is extremely narrow compared to the electromagnet pole area S, the magnetic flux density φ/S at the pole attraction surface is extremely small compared to that of the steel plate group 3, and the attraction force is also Even if the current of the excitation coil 2 is adjusted to change the magnetomotive force (AT ampere turns), the upper part of the steel plate group 3 will be damaged due to a very small excitation change.
The magnetic flux in each steel plate and the magnetic flux at the contact surfaces between the steel plates change greatly, making it extremely difficult to control the magnetic flux and making it difficult to select the desired number of steel plates. was extremely difficult.

The purpose of this invention is to eliminate the above-mentioned conventional problems, and its gist is that a part of the attracting pole that constitutes the magnetic circuit has a hysteresis characteristic that is different from the magnetic hysteresis characteristic of the yoke material. By using a dissimilar magnetic material and utilizing the property that the dissimilar magnetic material is hardly magnetized as long as the magnetomotive force applied to the excitation coil is small, an effect similar to that of providing a partial air gap to the attracting pole can be obtained. By narrowing the equivalent attraction cross-sectional area, the magnetic flux density in that area is increased, making it easier to sort thin steel sheets, and conversely, when the excitation force is increased, this dissimilar magnetic material has a magnetic flux density close to that of the yoke material. It is characterized by being configured so that the equivalent cross-sectional area is widened by being magnetized in the state, and the penetration depth of the magnetic flux is deepened, thereby increasing the number of steel plates that can be lifted. It can be effectively applied to electromagnets of any polar structure without being limited to the embodiments described above.

Next, one embodiment of the invention will be explained with reference to FIGS. 3 and 4. In order to make it easier to understand the structure of the electromagnet according to the present invention, FIGS. 4 is a schematic diagram of a plan view and a side sectional view, in which 4 is a yoke, 5 is a magnetic pole, and 6 is an excitation coil.

The yoke 4 is integrally connected to the pole A, and is made of a material with a hysteresis characteristic similar to that of the pole A, which is made of a magnetic material with a small coercive force, and its magnetic characteristics are as shown by the broken line 7 in FIG. It has hysteresis characteristics.

The magnetic pole 5 is made of a ferromagnetic material with a large coercive force, with its end face serving as an attracting surface, and is incorporated into the yoke 4 so as to form a magnetic circuit in parallel with the pole A at the location that constitutes the attracting pole of the electromagnet. It has a pole B, and its magnetic characteristics have a hysteresis characteristic as shown by the solid line 8 in FIG. The ratio of the cross-sectional areas of the suction surfaces of the poles A and B is determined by taking into account conditions such as the thickness range of the steel plate to be suctioned and the maximum lifting capacity. The magnetic pole 5 can be attached using known technical means, for example, by drilling a plurality of vertically penetrating holes inside the magnetic pole 5 and fixing the magnetic pole 5 to the yoke 4 by passing tightening bolts through the holes.

Pole B and pole A may form a parallel magnetic path, and may be provided on the outside of the pole as shown in the figure, or in the center of pole A to separate pole A, or may be provided in the center of pole A to separate pole A. It may also be a distributed arrangement structure in which the divided magnetic poles 5 are incorporated into the yoke 4. In addition, the materials used to construct the pole A and the yoke 4 are usually electromagnetic mild steel, structural rolled carbon steel, grain-oriented silicon steel, cast steel, etc., and the materials used to construct the magnetic pole 5 are cast magnetic steel, hardened magnetic steel, etc. Magnetic steel or the like is used.
Now, if the height of the magnetic pole 5 in the direction parallel to the magnetic path through which the magnetic flux of the pole B passes is L, then in the magnetic path from the attraction surface to L, the height of the magnetic pole 5 is
Since the magnetomotive force required at the pole A of the yoke 4 must be equal within the same height range as the magnetomotive force required at the pole A, the following statement holds true.

HAXL=HBXL・・・・・・・・・・・・・・・(
1) However, HA is the pole A when constant excitation is applied to the coil.
Similarly, HB is the magnetic field strength at pole B, expressed in AT/m. In addition, the magnetic flux densities at poles A and B corresponding to HA and HB are BA (Wb/Tlf) and BB (Wb/A), and the magnetic permeability of the respective hysteresis characteristics is μA and μB. The ratio of magnetic flux density on the surface is as follows. Generally B=μ×H
Since the relationship holds true, from equation 1), HA=HB BA/μA=BB/μB : BA/BB=μA/μB.

Therefore, when a current is passed through the excitation coil 6 of an electromagnet in which the yoke 4 is made of cast steel and the pole 5 is made of alnico V magnet material, the effect is as follows.

In other words, when the excitation current is small and the excitation force applied to the coil is small, for example, when the hysteresis characteristics 7 and 8 in Fig. 5 act on the operating line 9, BA/BB
= 1.3/0.06+22, and if the adsorption area S of pole A and pole B is the same, then the adsorption force Fc (B2・S, so if the adsorption force of pole A is 1, then the adsorption force of pole B is The adsorption force becomes 1/480, and the difference is so large that it can be safely considered that the adsorption force of pole B is equivalent to providing a gap to pole B.In addition, in this case, pole A of height L The magnetomotive force required for the part or pole B part is HAL (or HBL) = 2.4X104X
L(AT), and the larger L is, the larger the coil magnetomotive force at that point is, and the influence of the consumed magnetomotive force due to the external intervening gap is also reduced, making control easier. Next, if the excitation force by the coil is relatively large and acts on the operating line of 10, then B7. = 1.62/1.35 x 1.2, and as above, if the adsorption force of pole A is 1, then the adsorption force of pole B will be about 1/4, and the difference will be small. will fully demonstrate its function as an adsorption electrode.

Note that as the current applied to the excitation coil 6 is gradually increased and the magnetomotive force generated in the coil becomes larger, the difference in attraction force between the attraction surfaces of poles A and B disappears, and pole B becomes more effective as an effective pole. will increase. FIG. 6 shows the state in which the magnetic flux flows when the excitation force applied to the excitation coil 6 is weak, and FIG. 7 shows the state in which the magnetic flux flows when the excitation force applied to the excitation coil 6 is strong, as indicated by broken line arrows 11.

Furthermore, the attraction force can be eliminated by appropriately selecting and passing a current opposite to the above-mentioned current through the excitation coil 6.

If all the attracting poles are made of pole material with hysteresis characteristics (Fig. 4B) shown by the solid line in Fig. 5, the relationship between magnetomotive force and magnetic flux density will be as shown by the curve shown by the solid line in Fig. 5. If the magnetomotive force is small (72 AT/m or less),
Although the number of magnetic fluxes evenly distributed and flowing inside the attracting pole is small, the penetration depth of the magnetic flux in the attracted steel plate increases in proportion to the attracting pole area, so the number of magnetic fluxes flowing through the desired number of steel plates decreases. However, it has the disadvantage that it is difficult to select the desired number of steel plates because the required suction force cannot be exerted to attract the desired number of steel plates.

In the present invention, a magnetic path is formed in the attracting part of the attracting pole in parallel with a pole material having a hysteresis characteristic similar to that of the yoke material and a different kind of pole material having a hysteresis characteristic different from the magnetic hysteresis characteristic of the yoke material. When the magnetomotive force is small, the attraction cross section of the attraction pole is narrowed and the magnetic flux density at the attraction pole is increased, making it easier to sort thin steel sheets. It is possible to increase the suction cross-sectional area and increase the number of steel plates that can be lifted. According to this invention, by configuring a magnetic pole by combining relatively easily available materials with different magnetic hysteresis characteristics (largely different initial magnetic permeability), the contact area of the electromagnetic attracting pole to the object to be attracted can be increased. Since it has the function of changing equivalently, even if the power supplied to the excitation coil has relatively low precision, it can be expected to have a sufficient effect in sorting steel sheets. In addition, in conventional electromagnets of this type, the contact area was changed by moving the attracting pole up and down using a mechanical drive mechanism or by creating a gap, but this is not necessary with the present invention, and therefore the weight is reduced accordingly. Moreover, since the structure is relatively simple, operation is extremely easy, and there are almost no occurrences of malfunctions.

[Brief explanation of the drawing]

1 and 2 show a plan view and a side sectional view of a conventional lifting electromagnet, FIGS. 3 and 4 show a plan view and a side sectional view of a lifting electromagnet according to the present invention, and FIG. 5 shows magnetic hysteresis characteristics. The curve diagrams, FIGS. 6 and 7 are explanatory diagrams showing the flow state of magnetic flux when an excitation force is applied to the coil. 4...Yoke, 5...Magnetic pole, 6...
... Excitation coil 7 ... Hysteresis curve of pole A material, 8 ... Hysteresis curve of pole B material, 9.
...Operating line in the region of small magnetomotive force, 10...
...Operating line in the region of large magnetomotive force, 11...
・Magnetic flux.

Claims (1)

[Claims] 1. In the adsorption part of the adsorption pole of the lifting electromagnet, we use a pole material with a hysteresis characteristic comparable to that of the yoke material, and a different kind of pole material with a hysteresis characteristic different from the magnetic hysteresis characteristic of the yoke material and a characteristic with a large holding force. are assembled in parallel to form a magnetic path, and if the excitation force applied to the coil is small, the pole surface of the different pole material will hardly act as an attractive pole, and only when the excitation force is large, the pole surface will be attracted. A suspended electromagnet characterized by functioning as a pole.