Data processing: financial – business practice – management – or co – Automated electrical financial or business practice or... – Operations research or analysis
Reexamination Certificate
1998-02-06
2001-01-30
Stamber, Eric W. (Department: 2765)
Data processing: financial, business practice, management, or co
Automated electrical financial or business practice or...
Operations research or analysis
C702S082000, C702S083000, C702S084000, C700S109000, C700S110000
Reexamination Certificate
active
06182049
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method and associated system for diverting a number of production units to a designated processing area in a manufacturing line and more particularly a method and associated system for selecting and diverting a limited sample of units for product quality testing and/or analysis.
BACKGROUND OF THE INVENTION
Within a manufacturing line, it is sometimes necessary to have a limited number of production units over a given time go through particular designated areas of the manufacturing line, for instance to be tested and/or analyzed. Often a list of sequential process steps is specified for each production unit to denote each step that must be completed before the unit may proceed to the next step.
A testing and/or analysis operation is often a time-consuming operation, therefore it is desirable to sample only a limited number of production units on which to perform such tests, using sampling techniques designed to assure the sample group is representative of the pool of all production units. Precisely because the results of testing or analysis so performed on the sample group is considered to be representative of the pool from which the sample was taken, every unit in the pool is a candidate for selection into the sample group, even though the majority of these production units are not ultimately selected to be in the sample group that is actually tested and/or analyzed.
In a production line where only a limited number of units are selected for inspection, and where this selection requires diverting a selected unit from the normal flow of the production line to a designated station, there is need for a selection process which does not impede the normal flow of the production line. Such process, and the system implementing the process, must select representative units for testing without creating a back up of units during the selection process. In the past, all units waited in the queue for the designated station, while this selection was made randomly and manually by multiple workers using frequency logs to track the number or units tested or analyzed per weekly period. Typically, the manufacturing line backed up awaiting this determination, resulting in increased manufacturing time for all production units.
Systems and methods for scheduling or controlling work through manufacturing processes and/or collecting manufacturing data and applying it to process controllers are known.
U.S. Pat. No. 4,691,830, issued to Ahl et al. and assigned to Owens-Illinois, Inc., describes a completely automated system for inspection and sorting of molded containers, such as glass bottles, in a manufacturing process. The system in Ahl et al. is restricted to molded container manufacture, but is capable of distinguishing differing container cavity designs, automatically sampling a single container from each design for inspection at a predetermined time interval, comparing the inspection results with predetermined data and determining if a re-sample is required, automatically diverting all containers of a newly encountered cavity design for inspection until a predetermined number is reached, and automatically resetting upon a predetermined time corresponding to the factory worker shift change.
What is missing from the prior art, however, is a sampling process and associated system implementing a process that prevents production backups at the point of sampling while at the same time assuring representative sampling by selecting production units on the basis of a number of a combination of criteria, such as predetermined time intervals, response to the total number of units produced, and a periodic quota.
SUMMARY OF THE INVENTION
There is provided by the present invention, a method and associated system for selecting a quantity, usually a limited number, of units or lots to go to a designated area, usually for testing or analysis, based on predetermined criteria for the time interval between selections, the maximum quantity of units that can consecutively bypass testing or analysis, and the maximum quantity of units that will be selected in a given time period, for instance in a week. The present invention also provides overriding ability to ignore the predetermined criteria and divert any arbitrary number, including all units, to the designated area.
More particularly, for a manufacturing line wherein a plurality of production jobs are performed on a plurality of units in a plurality of processing areas, the present invention comprises a method for diverting a number of said plurality of production units to a designated area other than the plurality of processing areas, comprising the steps of:
a) counting the number of production units that bypass the designated area beginning every time a production unit is diverted to the designated area, to obtain a unit bypass count;
b) counting the number of units diverted to the designated area to obtain a selected unit count;
c) measuring a first time interval beginning every time a production unit is diverted to the designated area;
d) comparing the unit bypass count, selected unit count and the first time interval to a preset value for each of said unit bypass count, selected unit count and first time interval respectively; and
1) diverting one of said plurality of units to the designated area when the measured first time interval is equal to or greater than the preset value for the first time interval and the selected unit count is less than the preset value for the selected unit count;
2) diverting one of said plurality of units to the designated area when the unit bypass count is equal to or greater than the preset value for the unit bypass count and the selected unit count is less than the preset value for the selected unit count.
Preferably, in the above method, steps (a) through (d) are performed for a preset time period, most preferably a week. At the expiration of the preset time period, the selected unit count is set to zero and steps (a) through (d) are repeated.
More preferably, any number of said plurality of units may be associated with an override marker, and the method further comprises diverting a unit so associated with said marker to the designated area without performing step (d).
There is also provided according to this invention, a system capable of implementing the above method, which system comprises:
a first clock which measures a first time interval beginning every time a production unit is diverted to the designated area and outputs a first time interval signal having a value representing said time interval,
a unit bypass counter which outputs a unit bypass count signal having a value representing the number of production units that have bypassed the designated area since the last unit diverted to the designated area,
a selected unit counter which outputs a selected unit count signal having a value representing the number of units diverted to the designated area,
a memory containing a preset value for the unit bypass count, a preset value for the selected unit count and a preset value for the first time interval,
a controller connected to the memory, to the first clock, to the unit bypass counter, and to the selected unit counter, said controller including a comparator for comparing the value of the signal from the bypass counter, from the selected unit counter, and from the first time clock to the respective preset values stored in said memory, said controller also including a unit selection device to divert one of the plurality of units to the designated area, when any one of the following two conditions are present:
(1) the value of the first time interval signal is greater than or equal to the preset value for the first time interval, and the value of the selected unit count signal is less than the preset value for the selected unit count; or
(2) the value of the unit bypass count signal is greater than or equal to the preset value for the unit bypass count, and the value of the selected unit count signal is less than the preset value for the selected unit count.
The system may furthe
Barker Brian C.
Bauer Lawrence R.
Chaloux Susan E.
Federico John T.
Hartswick Perry G.
International Business Machines - Corporation
Ratner & Prestia
Stamber Eric W.
Vincent Steven F.
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