Thru-stroke tipping moment severity monitor

• US 6,487,506 B1
• Filed: 05/26/2000
• Issued: 11/26/2002
• Est. Priority Date: 10/15/1999
• Status: Expired due to Term

• Current Assignee: The Minster Machine Company (Nidec Corporation)
• Original Assignee: The Minster Machine Company (Nidec Corporation)
• Inventors: Schoch, Daniel A.
• Primary Examiner(s): Hilten, John S.
• Assistant Examiner(s): Washburn, Douglas N
• Application Number:
  US09/579,797
• Time in Patent Office: 914 Days
• Field of Search: 364/475, 364/474, 364/551, 364/551.02, 364/552, 364/511, 700/174, 700/206, 702/34
• US Class Current: 702/34
• CPC Class Codes: B30B 15/0094 Press load monitoring means B30B15/281 takes precedence
• CPC Class Codes: B30B 15/28 Arrangements for preventing distortion of, or damage to, presses or parts thereof

Abstract

An apparatus and method for monitoring the tipping moment severity of a mechanical press for the purpose of accurately predicting die reliability. The method includes generating a unique tipping moment severity chart for the press application to be monitored and continually monitoring the tipping moment level during production operation of the press. Apparatus is used to monitor the applied load which is communicated to a computational device for computing and plotting tipping moment severity on the tipping moment severity chart.

Claims

1. An apparatus for monitoring the die reliability condition of a running press, the running press having a bed, said apparatus comprising:

at least one load sensor for sensing a load value, said at least one load sensor attached to the bed of the running press; and

a computational device for computing a plurality of computed values, said device storing a plurality of data relating to the running press and receiving the load value from said at least one load sensor, wherein one of said plurality of computed values is a measure of the tipping moment severity of the running press based on said sensed load value from said at least one load sensor, said computational device communicatively connected to said at least one load sensor.

2. The apparatus as recited in claim 1, wherein said computational device comprises:

a microprocessor.

3. The apparatus as recited in claim 1, wherein said plurality of data stored in said computational unit comprises:

a unique tipping moment severity chart for the running press;

a plurality of tipping moment severity factors corresponding to a plurality of zones representing differing tipping moment severity levels which form a part of said tipping moment severity chart; and

a plurality of zone of criticality factors corresponding to a plurality of zones of criticality which form a part of said tipping moment severity chart.

4. The apparatus as recited in claim 2, wherein one of said plurality of computed values computed by said computational device is a measure of die life risk condition.

5. The apparatus as recited in claim 1, further comprising:

a digital storage device for storing at least one of said plurality of computed values, said digital storage device communicatively connected to said computational device.

6. The apparatus as recited in claim 1, further comprising:

a modem for communicating at least one of said plurality of computed values to a remote location, said modem communicatively connected to said computational device.

7. The apparatus as recited in claim 1, further comprising:

a display device for displaying at least one of said plurality of computed values, said display device communicatively connected to said computational device.

8. The apparatus as recited in claim 1, further comprising:

an alert device for producing an alert signal if at least one of said plurality of computed values exceeds a predetermined measure, said alert device communicatively connected to said computational device.

9. The apparatus as recited in claim 1, further comprising:

a shutoff device for discontinuing press operation if at least one of said plurality of computed values exceeds a predetermined measure, said shutoff device communicatively connected to said computational device.

10. A method of monitoring the die reliability condition of a running press, the running press having a bed, said method comprising:

monitoring the tipping moment severity of the running press.

11. The method of claim 10, wherein said step of monitoring the tipping moment severity of the press comprises:

placing at least one load sensor on the bed of the running press;

providing a computational device;

communicating the load sensed by the load sensor to the computational device; and

computing the tipping moment severity of the press using the sensed load value.

12. A method of generating, for a particular press and die set, a unique tipping moment severity chart, comprising:

dividing the ordinate of a tipping moment severity versus slide vertical position graph into a plurality of zones representing differing tipping moment severity levels;

plotting the slide vertical motion on said tipping moment severity chart;

dividing the ordinate of the tipping moment severity versus slide vertical position graph into a plurality of zones of criticality representing differing phases of punch travel;

projecting the zones of criticality onto the plot of slide vertical motion; and

projecting the zones of criticality from the plot of slide vertical motion to the abscissa.

13. The method of claim 12, wherein said step of dividing the ordinate into a plurality of zones of criticality further comprises:

defining three zones of criticality which represent free punch travel, load development delay on material upper surface punch travel through the stock material and punch travel through the die.

14. The method of claim 12, wherein said step of dividing the ordinate into a plurality of zones representing differing tipping moment severity levels further comprises:

defining four zones of tipping moment severity on the positive portion of the ordinate; and

defining four zones of tipping moment severity on the negative portion of the ordinate.

15. A method of monitoring the die life risk condition of a mechanical press comprising:

monitoring the tipping moment severity of the press;

generating a unique tipping moment severity chart for the press;

plotting the monitored tipping moment severity of the press on the unique tipping moment severity chart for the press;

providing a computational device; and

computing the die life risk condition of the press.

16. The method of claim 15, wherein said step of generating a unique tipping moment severity chart for the press further comprises:

dividing the ordinate of a tipping moment severity versus slide vertical position graph into a plurality of zones representing differing tipping moment severity levels;

plotting slide vertical motion on said tipping moment severity chart;

dividing the ordinate of the tipping moment severity versus slide vertical position graph into a plurality of zones of criticality representing differing phases of punch travel;

projecting the zones of criticality onto the plot of slide vertical motion; and

projecting the zones of criticality from the plot of slide vertical motion to the abscissa.

17. The method of claim 16, wherein said step of generating a unique tipping moment severity chart for the press further comprises:

determining a plurality of tipping moment severity factors corresponding to the plurality of zones representing differing tipping moment severity levels; and

determining a plurality of zone of criticality factors corresponding to the plurality of zones of criticality which correspond to differing phases of punch travel.

18. The method of claim 17, wherein said step of computing the die life risk condition of the press further comprises:

determining the duration of the positive peak tipping moment severity level;

determining the duration of the negative peak tipping moment severity level;

determining the tipping moment severity factor associated with the positive peak tipping moment severity level;

determining the tipping moment severity factor associated with the negative peak tipping moment severity level;

determining the zone of criticality factor associated with the positive peak tipping moment severity level;

determining the zone of criticality factor associated with the negative peak tipping moment severity level;

computing a die life risk condition component value associated with the positive peak tipping moment severity level using the duration of the positive peak tipping moment severity, the tipping moment severity factor associated with the positive peak tipping moment severity and the zone of criticality factor associated with the positive peak tipping moment severity level;

computing a die life risk condition component value associated with the negative peak tipping moment severity level using the duration of the negative peak tipping moment severity, the tipping moment severity factor associated with the negative peak tipping moment severity and the zone of criticality factor associated with the negative peak tipping moment severity level; and

computing a die life risk condition of the press by summing the die life risk condition component value associated with the positive peak tipping moment severity level and the die life risk condition component value associated with the negative peak tipping moment severity level.

19. The method of claim 17, wherein said step of computing the die life risk condition of the press further comprises:

determining the duration of the positive peak tipping moment severity level;

determining the duration of the negative peak tipping moment severity level;

determining the tipping moment severity factor associated with the positive peak tipping moment severity level;

determining the tipping moment severity factor associated with the negative peak tipping moment severity level;

determining the zone of criticality factor associated with the positive peak tipping moment severity level;

determining the zone of criticality factor associated with the negative peak tipping moment severity level;

computing a die life risk condition component value associated with the positive peak tipping moment severity level using the positive peak tipping moment severity, the duration of the positive peak tipping moment severity, the tipping moment severity factor associated with the positive peak tipping moment severity and the zone of criticality factor associated with the positive peak tipping moment severity level;

computing a die life risk condition component value associated with the negative peak tipping moment severity level using the negative peak tipping moment severity, the duration of the negative peak tipping moment severity, the tipping moment severity factor associated with the negative peak tipping moment severity and the zone of criticality factor associated with the negative peak tipping moment severity level; and

computing a die life risk condition of the press by summing the die life risk condition component value associated with the positive peak tipping moment severity level and the die life risk condition component value associated with the negative peak tipping moment severity level.

20. The method of claim 17, wherein said step of computing the die life risk condition of the press further comprises:

determining the tipping moment severity factor associated with the positive peak tipping moment severity level;

determining the tipping moment severity factor associated with the negative peak tipping moment severity level;

determining the zone of criticality factor associated with the positive peak tipping moment severity level;

determining the zone of criticality factor associated with the negative peak tipping moment severity level;

computing a die life risk condition component value associated with the positive peak tipping moment severity level using the tipping moment severity factor associated with the positive peak tipping moment severity and the zone of criticality factor associated with the positive peak tipping moment severity level;

computing a die life risk condition component value associated with the negative peak tipping moment severity level using the tipping moment severity factor associated with the negative peak tipping moment severity and the zone of criticality factor associated with the negative peak tipping moment severity level; and

computing a die life risk condition of the press by summing the die life risk condition component value associated with the positive peak tipping moment severity level and the die life risk condition component value associated with the negative peak tipping moment severity level.

21. The method of claim 17, wherein said step of computing the die life risk condition of the press further comprises:

associating the monitored tipping moment severity with the appropriate zone of criticality factor;

computing the absolute value of the monitored tipping moment severity;

computing a weighted tipping moment severity value using the absolute value of the monitored tipping moment severity and the zone of criticality factor associated with the monitored tipping moment severity;

recording weighted tipping moment severity values versus time; and

generating a cumulative tipping moment severity value for one slide stroke using the weighted tipping moment values versus time.

22. The method of claim 17, wherein said step of computing the die life risk condition of the press further comprises:

associating the monitored tipping moment severity with the appropriate tipping moment severity factor;

associating the monitored tipping moment severity with the appropriate zone of criticality factor;

computing the absolute value of the monitored tipping moment severity;

computing a weighted tipping moment severity value using the absolute value of the monitored tipping moment severity, the tipping moment severity factor and the zone of criticality factor associated with the monitored tipping moment severity;

recording weighted tipping moment severity values versus time; and

generating a cumulative tipping moment severity value for one slide stroke using the weighted tipping moment values versus time.

23. An apparatus for monitoring the die reliability condition of a running press, the running press having a bed, said apparatus comprising:

at least one load sensor for sensing a load value, said at least one load sensor attached to the bed of the running press;

a computational device for computing a plurality of computed values, said device storing a plurality of data relating to the running press and receiving the load value from said at least one load sensor, wherein one of said plurality of computed values is a measure of the tipping moment severity of the running press based on said sensed load value from said at least one load sensor, said computational device communicatively connected to said at least one load sensor; and

a data plotting device communicatively connected to said computational device, said data plotting device configured for graphically charting said measure of the tipping moment severity.

24. A method of monitoring the die reliability condition of a running press, the running press having a bed, said method comprising:

monitoring the tipping moment severity of the running press;

generating at least one tipping moment severity value as a result of said step of monitoring; and

plotting each said tipping moment severity value graphically.

25. The method of claim 24, wherein said step of monitoring the tipping moment severity of the press comprises:

placing at least one load sensor on the bed of the running press;

providing a computational device; and

communicating the load sensed by the load sensor to the computational device; and

said step of generating at least one tipping moment severity value comprising;

computing one said tipping moment severity value using the sensed load value.