AN ELECTROMAGNET FOR MOVING IRON OBJECTS

Abstract: Electromagnet for moving iron objects. It is formed with opposing magnetic heads (M<u1>u, M<u2>u), mounted at the ends of a carrying shaft (1), to which is also attached a steel cable (9). The electromagnet (M<u1>u, M<u2>u) can be raised and lowered with the help of the cable (9). By the magnetic heads (M<u1>u, M<u2>u) being attached to the shaft (1) by ball joints, a vertical line from a suspension point in a suspension means for the cable (9) carrying the electromagnet goes practically straight through the centre of gravity for the magnetic heads and the iron object to be lifted. A very safe lift is therefore obtained when lifting with the electromagnet.

Description: An electromagnet for moving iron objects The invention relates to an electromagnet for moving iron objects. The electromagnet is primarily intended for use in auto- matically handling details arranged in no particular order, Examples of such handling are the transfer of iron details from one transport pallet to another, from a pallet to a conveying, path, and from such a path to a machine tool, or the reverse. For moving iron objects with the electromagnet, it has been given the characterizing features disclosed in the appended patent claims. An embodiment of the electromagnet in accordance with the invention is illustrated on the accompanying drawings, on which Figure 1 illustrates the electromagnet as seen at an angle from above, and Figure 2 illustrates the magnetic heads with their windings, as seen from one side. The embodiment illustrated on the drawings will now be described in detail. The electromagnet in accordance with the invention is provided with two opposing magnetic heads M, and M-. Each of these is provided with at least one electric winding A,, A-. respectively. The heads M-, M~ are connected to each other via a carrying shaft 1. The magnetic heads M, , M- of the electromagnet shown on the drawing are furthermore provided with a second elect¬ ric winding " B1, and B2_, respec,ti.vel.y. r The magnetic heads M. and M_ are formed one to the oppos hand of the other. Each is provided with two opposing pole plates, an outer 2, 3 and an inner 4, 5. On the respective magnetic head M,, M_ the outer pole plate 2, and the inner pole plate 4, 5 are mutually attached by a cylindrical core 6. Electrical windings A,, B, and A--, for the respective magnetic head M, , M 2 are wound on the respective core 6. The ends of the carrying shaft 1 connecting the magnetic heads M, , and M 2 with each other areprovided with ball joints (not shown on the drawings) , attached to the core of the respective magnetic head M, , M~. On the respective magnetic head M, , M- the inner pole pl 4, 5 is formed with an aperture 7 directly opposite the cylindrical core 6. Said aperture opens out onto the cor 6 where the ball joint is attached, and the carrying sha 1 runs through the apertue 7 to the ball joint. The diam of the aperture 7 is relatively large compared with the cross section of the carrying shaft 1, so that the magne heads M- and M- can assume positions at approximately 90 in relation to each other for ensuring that a planar surface at the edges of the pole plates 2, 4 and 3, 5 on the respective magnetic head M-, and - can be tipped int engagement against the surface of an iron object to be lifted by the electromagnet. By attaching the magnetic heads M, and __ 2 to the carrying shaft 1 by ball joints, they are also turnable, so that a suitable portion of th edges of the pole plates 2, 4 and 3, 5 are turned into engagement against the iron object which is to be lifted by the electromagnet. Turning and tipping the magnetic heads M, and 2 is done when the windings A and B are connected to their current sources and the heads M, and M 2 are adjacent the iron object to be lifted. An attachment 8 for a steel cable 9 is arranged at the middle of the carrying shaft 1. The magnetic heads M, and M 2 , mounted at the ends of the carrying shaft 1, are raised and lowered with the help of the cable 9. The cable 9 goes to a point of support on a suspension means (not shown on the drawings) for the electromagnet. Raising and lowering the electromagnet is carried out by this suspen¬ sion means. By this suspension of the electromagnet there will be, during a lift, a vertical line through the suspension point of the wire 9 in the suspension means, this line going practically straight through the centre of gravity for the magnetic heads M, and M 2 and the iron object which is to be lifted. It is thus ensured that the electro¬ magnet always takes hold of the iron object to be lifted. This is of particularly great importance when the lifting work of the electromagnet is made automatic. To ensure that the pole plates 2, 4 and 3, 5 of the electro¬ magnet will come into contact with the iron objects to be lifted with a sufficiently large surface in all positions, the lower edge 10 of the inner pole plates 4, 5 is double-chamfered. For the same reason, one or more edges 11, 12 on the outer pole plates 2, 3 are be¬ velled. So that the cable 9 will not prevent the magnetic heads M and M~. to get into line with the vertical line from the suspension point of the cable 9 in the suspension means OMPI for the electromagnet through the centre of gravity of the magnetic heads and the iron object which is to be lifted, the upper edge 13 on the inner pole plates 4, 5 is proveded with a wide acute bevel towards the cable 9 The electromagnet is made magnetic and is demagnetized by the windings A, , B-. and 2 , B 2 on the respective magnetic head M, and IV - The first winding A, , A 2 consists of a heavy-gauge wire with few turns. The second winding B, , B_- consists of a fine-gauge wire with many turns. To automatically seed out the iron object which is to b lifted by the electromagnet, the windings A, , A- are connected to a weak DC source. When the electromagnet m an iron object, a voltage is induced in the second wind B, , B 2 . The voltage impulse can then go to the control means of the electromagnet to lower the electromagnet towards the iron object to be lifted. Energizing the magnet is done by a powerful DC source being connected to the windings A, and A_. This current several times as great as the normal working current of the magnet. The magnet will then twist towards the good intended for handling. After connecting the windings A, and A- to the heavy DC source for a given time, they are switched to the norma electrical lifting power, i.e. normal current strength. " _ KEA { / Oiv'Pl J Further, the electromagnet in accordance with the inven¬ tion can be provided with a demagnetizing coil supplied with low-frequency AC current at 2-10 Hertz, which causes the residue magnetism to decay and prevents an iron object handled by the electromagnet from being magnetized or becoming attached to the magnet. The magnetic heads M, and M- are mounted at the ends of the carrying shaft..1. The carrying shaft 1 is of a length such that the magnetic fields from the respective magnetic head generated during lifting with the magnets will not interfere with each other. An example of how the electromagnet in accordance with the invention can operate for automatic handling of unoriented iron objects will now be described. A braced framework is constructed such that two standart loading pallets can be placed side-by-side inside it. The framesork is constructed such that a trolley, carried in the upper portion of the framework, can reach all points in the layout plan of the pallets. The trolley carries the electromagnet in accordance with the present invention, and the electromagnet is arranged raisable and lowerable. It is assumed that the framework is placed at a painting line loop. A truck driver sets down two pallets inside the framewor - One pallet is loaded with painted iron details. The other is an empty pallet. The electromagnet is taken by the trolley over the loaded pallet. Its movement follows its programming. The electromagnet then functions as a trans¬ mitter for the movements of the trolley. When the electromagnet approaches an iron object, a voltage is induced in the windings 2 and B 2 . The search is arrested. The electromagnet is switched over to magne tic function. Its exact position in space can be program med, e.g. by a magnetiza&le steel tape, fitted parallel a driving cylinder on the trolley. After the magnetizing winding of the electromagnet has been coupled in, an iro article is attracted to the electromagnet and the latter is lifted together with the article. The article lifted by the electromagnet is conveyed together with the electromagnet by the trolley to an unloading station on the painting line. Demagnetization is switched on to unload the iron article This is done with AC current at a frequency of 2-10 Hertz This facilitates release of light iron goods which has been magnetized. The demagnetization also makes sub¬ sequent work on the iron article easier. The electromagnet is subsequently taken by the trolley to a station for ready-painted iron articles. There, an iron article is lifted bythe electromagnet and taken by the trolley to the empty pallet. The article is loaded onto the empty pallet at the same location as it was lifted from the full pallet. To obtain a satisfactory system for giving impulses for the movements of the electromagnet, one or more magnetiz¬ able steel tape can be fitted parallel to the path of the trolley, and for the raising and lowering movements of the electromagnet. A plurality of fixed and movable magnetizing and demagnetizing heads are fitted for every such magnetizable steel tape, or the like. These heads are made so that the information point on the steel . tape is either momentary or elongate. By "elongate information point" is meant a magnetic curve on the tape which is decreasing, either in power, frequency or form.

Claims: PATENT CLAIMS: 1. An electromagnet for lifting iron objects, c h a r a c t e r i z e d i n that the electromagnet is provided with two opposing magnetic heads (M, and M-) each provided with at least one electric winding (A, and A 2 , respectively) , that the magnetic heads (M-, , M 2 ) are connected by a carrying shaft (1) , that the ends of the carrying shaft (1) are provided with ball joints attached to the magnetic heads (M, , M 2 ) and that the carrying shaft (1) , suitably at its middle, is provided with an attachment (8) for a lifting means, e.g. a steel cable (9) , for raising and lowering the electro¬ magnets (M, , M 2 ) so that when lifting with the electromagnet, a vertical line from a suspension point in a suspension means for the electromagnets (M, , M-,) goes practically straight through the centre of gravity for the magnetic heads (M, , M~) and the iron object which is to be lifted. 2. An electromagnet as claimed in claim 1, c h a r a c t e r i z e d i n that the magnetic heads (M. , M-) are formed one to opposi hand of the other, each being provided with two opposing pole plates (2, 4 and 3, 5, respectively) connected by a cylindrical core (6) . 3. An electromagnet as claimed in claim 2, c h a r a c t e r i z e d i n that an edge (11) on the outer pole plate (2, 3) is bevelled. 4. An electromagnet as claimed in claim 3, c h a r a c t e r i z e d i n that an upper edge (10) on the inner pole plate (4, 5) is double-chamfered. 5. An electromagnet as claimed in claim 3, c h a r a c t e r i z e d i n that an upper edge (13) on the inner pole plate (4, 5) is provided with a wide acute bevel. 6. An electromagnet as claimed in any of claims 1-5, c h a r a c t e r i z e d i n that the ball joints are attached to the cylindrical core of each magnetic head (M, , M 2 ) . 7. An electromagnet as claimed in claim 6, c h a r a c t e r i z e d i n that the inner pole plate (4, and 5 respectively) on one magnet head (M, ) on the side facing towards the inner pole plate (4 and 5, respectively) on the other magnetic head (M 2 ) has provided in its surface an aperture (7) intended for the carrying shaft (11) , and opening out at the cylindrical core (6) where the ball joint is attached. 8. An electromagnet as claimed in any of claims 1-7, c h a r a c t e r i z e d i n that the first windi-ng (A, , A 2 ) on the respective magnetic head (M, , M 2 ) is connectable to a DC source for seeking out the iron object by inducing a voltage when the object is approached. 9. An electromagnet as claimed in claim 7 or 8, c h a r a c t e r i z e d i n that the windings (A_, B_.) on the second magnetic head (ϊ_ 2 ) are connectable to a powerful DC source. OMPI _ . WiP0 _ 10. An electromagnet as claimed in claim 9, c h a r a c t e r i z e d i n that when two windings (A,, B , A 2 , B 2 ) are used, the first winding (A,) on the first magnetic head (M,) is connectable to the power ful DC source a given time after connecting the second winding (B 2 ) on the second magnetic head (IV ) to the powerful DC source. 11. An electromagnet as claimed in claim 8 or 9, c h a r a c t e r ! z e d i n that the windings (A, , A 2 ) on the respective magnetic head (M, , M 2 ) are connectable to a normal DC source a given time after connecting the winding (A, ) to the power¬ ful DC source, to develop normal lifting power in the magnetic heads (M, and M 2 ) .

Inventors: WESTIN K
Applicants: WESTIN K
Application year: 1979
Main classification: B66C1
IPC codes: B66C1, H01F7