Weighing machines

Details Weighing machines Weighing machines

1998-07-17

2001-08-07

Gibson, Randy W. (Department: 2859)

Weighing scales

Weigher responsive material control

Discharge valve or gate

C177S108000, C177S109000, C251S212000, C222S503000

Reexamination Certificate

active

06271486

ABSTRACT:

The present invention relates to weighing machines.
Multi-head weighing machines comprise a number of hoppers to which a free flowing product may be fed by suitable means. The feed means is arranged to deliver quantities of the product to the hoppers each quantity being approximately a fraction (¼ or ⅓) of the desired target weight. The hoppers are connected to strain gauges or load cells by which the weights of their contents may be accurately measured . A combination of hoppers is then selected which when aggregated come closest to the desired target weight. The select hoppers are then discharged into a common chute to form the target weight.
Hitherto, hoppers used in such multi-head weighing machines have been closed at their lower ends by means of a pair of doors pivoted about horizontal axes and spring loaded towards one another to a closed position. A lever mechanism is provided to pivot the doors downwardly to an open position. The lever mechanism is controlled by an abutment member which is moved into engagement with the lever mechanism to open the doors. In the closed position, the abutment member is positioned clear of the lever mechanism, so that the hopper will be suspended freely for weighing purposes.
The hoppers used hitherto have several disadvantages. In particular, the complex linkage mechanism required to open and close the doors and the relatively large surface area of the doors. Furthermore, the product may stick to the pivoted doors, so that the full batch of product is not delivered to the discharge chute.
According to one aspect of the present invention a weighing machine includes at least one hopper, said hopper having a tubular body with closing means located adjacent its lower end, the closing means selectively opening and closing the lower end of the tubular body, said closing means comprising a plurality of plates pivotally mounted for movement in the plane transverse to the axis of the tubular body between; a closed position, in which the plates engage one another generally centrally of the bore of the tubular body; and an open position, in which the plates are disposed clear of the bore of the tubular body; and means being provided to drive the plates between their open and closed positions.
In accordance with the present invention, the surface areas of the plates is significantly less than that of the hopper doors used in existing designs and the mechanical linkages are simplified.
Furthermore, as the plates move transverse to the tubular body of the hopper, they may be arranged such that the side walls defining the tubular body will scrape the product off the plates, so that the full batch of product is transferred to the discharge chute.
According to a preferred embodiment of the present invention the plates of the closing means are arranged symmetrically of the tubular body, movement of the plates being such that the forces generated in the plane of movement will be balanced.
According to a further preferred embodiment the plates of the closing means are driven by a belt or chain, in reciprocating manner, through a drive pulley or sprocket. The drive pulley or sprocket is preferably driven by an external power source, the external power source being disengaged from the drive pulley or sprocket when the plates are in their closed position so that the hopper will be freely suspended for weighing purposes.


REFERENCES:
patent: 898689 (1908-09-01), Sawyer
patent: 2748998 (1956-06-01), Busald
patent: 4703874 (1987-11-01), Tapperman et al.
patent: 5340949 (1994-08-01), Fujimura et al.
patent: 5379923 (1995-01-01), Sagastegui et al.
patent: 5767453 (1998-06-01), Wakou et al.
patent: 5806725 (1998-09-01), Bennett
patent: 5895678 (1999-04-01), Sunter
patent: 6051070 (2000-04-01), Sunter
U.S. application No. 08/727,675, Bennett, filed Oct. 17, 1996.
U.S. application No. 08/791,315, Sunter, filed Jan. 30, 1997.

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