Conveyor belt system

• US 3,936,873 A
• Filed: 05/26/1972
• Issued: 02/03/1976
• Est. Priority Date: 11/14/1969
• Status: Expired due to Term

• Current Assignee: Santrade Ltd. (Sandvik AB)
• Original Assignee: Sandvik AB By Change of Name From Sandvikens Jernverks Aktiebolag
• Inventors: Alfredsson, Stig Allan Junior
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US05/257,451
• Time in Patent Office: 1,348 Days
• Field of Search: 360/1, 360/4
• US Class Current: 360/1
• CPC Class Codes: B07C 3/16 using magnetic detecting means for information carriers G06K7/08
• CPC Class Codes: B65G 47/503 the system comprising endless moving means

Abstract

A system is disclosed for controlling the discharge of articles from a steel belt conveyor. When articles are placed on the belt at the loading station, the belt is magnetized at a high intensity in a very small area which has a predetermined relationship, longitudinally of the belt, to the position of the article on the belt. The magnetized spot is also positioned transversely of the belt in accordance with the station where the article is to be discharged. At each discharge station there is an arrangement in the form of a plow and means to move the plow to and from the path of articles carried on the belt so as to deflect the articles from the belt. The plow operating mechanism has an electronic control which includes a Hall-effect transducer positioned adjacent the bottom surface of the belt and relatively positioned transversely of the belt along the path of the magnetized spots for that station. Hence, when an article is placed on the belt and the magnetized spot is produced corresponding to a particular unloading station. The article will be carried to that station and unloaded. The high intensity magnetization is produced by an electromagnet extending transversely from the bottom surface of the belt, and direct current is supplied to the electromagnet coil from a condenser circuit. The current can be caused to flow in either direction through the coil so as to produce a magnetized zone or spot of either north or south polarity. The magnetized zone or spot is surrounded by a ring of the opposite polarity but of insufficient intensity to energize the Hall-effect control unit. The number of discharge stations may be increased by producing two or more magnetized spots for various of the discharge stations.

Claims

1. In control means for a steel belt conveyor wherein the steel belt is of sheet steel and has top and bottom surfaces and extends along a conveyor run which carries load units to a plurality of discharge stations, the combination of, magnetizing means to produce magnetized signal portions in said belt in the form of magnetized spots, each of said magnetized signal portions comprising the entire portion of the belt between two opposite coextensive discrete areas of the belt surfaces at a predetermined distance from one edge of the belt, said magnetizing means being operative to substantially saturate each of said signal portions between its discrete surface areas with flux perpendicular to said belt surfaces and to thereby produce a magnetic pole of single-polarity throughout said signal portion, a plurality of detector means each of which is positioned adjacent said bottom surface of the belt at a zone along the belt path relative to the position of a selected discharge station, a plurality of cores of magnetizable material positioned respectively below each of said detector means opposite said bottom surface and extending therefrom away from said bottom surface whereby said core aids in concentrating magnetic flux paths through said detector means, control means responsive to the detection of a magnetized signal portion by each of said detector means, and means to discharge load units from said belt at each of said selected discharge stations in response to such detection by its detector means and under the control of said control means.

2. The control means described in claim 1 wherein said detector means comprises a Hall-effect generator.

3. Control means as described in claim 2 wherein said Hall-effect generator is connected to an amplifier and thence to a comparator circuit which produces an output signal which operates said means to discharge load units.

4. Apparatus as described in claim 1 wherein said means to discharge load units comprises means which swings across the top surface of the belt.

5. In the art of controlling the functioning of a sheet steel belt conveyor which carries load units upon its top surface along a path and in which the steel belt has a bottom surface, the method which comprises the steps of, producing a high intensity magnetic field in the steel belt spaced a predetermined distance from one edge thereof and having a predetermined position longitudinally of said belt with the lines of flux extending perpendicular to said belt surfaces and of an intensity to produce substantial saturation throughout the entire portion of the belt between opposite coextensive discrete areas of said belt surfaces and thereby magnetize said entire portion of the belt and create a signal spot which is magnetized with single polarity, moving said belt longitudinally whereby said signal spot moves along said path, detecting the magnetized condition of said signal spot upon passing a detecting zone at said selected station along said path to thereby produce a signal, and discharging a load unit from the belt at said selected station in response to said signal.

6. The method described in claim 5, wherein said magnetic field is produced by an electromagnet having its core perpendicular to the belt surface and wherein electricity is supplied to produce the magnetic field by discharging condenser means to thereby produce current flow of short duration.

7. The method described in claim 6 wherein the detecting of the arrival of a magnetized condition is performed by a Hall-effect generator which is connected through an amplifier to a comparator circuit thereby to produce said signal.

8. The method described in claim 5 wherein the discharging of the load unit is performed by swinging a deflector across the top surface of the belt.