Apparatus and process for protecting machinery

• US 3,979,980 A
• Filed: 03/10/1975
• Issued: 09/14/1976
• Est. Priority Date: 03/10/1975
• Status: Expired due to Term

• Current Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Original Assignee: Sherwin-Williams Company
• Inventors: Balciunas, Eugene T., Biester, Robert E.
• Primary Examiner(s): Abercrombie, Willie G.
• Application Number:
  US05/556,769
• Time in Patent Office: 554 Days
• Field of Search: 83/61, 83/62, 83/63, 83/58, 83/13, 408/7, 408/13
• US Class Current: 83/13
• CPC Class Codes: B21D 43/025 Fault detection, e.g. misfeed detection
• CPC Class Codes: G01P 13/00 Indicating or recording presence, absence, or direction, of movement electric switches H01H; counting moving objects G06M7/00
• CPC Class Codes: Y10T 83/04 Processes
• CPC Class Codes: Y10T 83/086 With sensing of product or product handling means
• CPC Class Codes: Y10T 83/088 Responsive to tool detector or work-feed-means detector
• CPC Class Codes: Y10T 83/091 Responsive to work sensing means

Abstract

An apparatus and process for protecting a press die and press frame from damage when stock has jammed therein. The apparatus includes a proximity sensor which senses metal entering the press, a proximity sensor to detect the stamped product, and a proximity sensor to detect the skeleton scrap metal left after the stamping. A press cycle detection sensor senses a cycle of the press and generates a timing pulse. Means for comparing signals generated by the proximity sensors is regulated by the timing pulse and includes a signal converter, a memory circuit, a signal comparator and a fault check operatively connected to one another. An output relay breaks the press circuit upon an appropriate signal.

The process of protecting a press die includes sensing the input to determine if stock is present, generating an electrical impulse and storing the signal in a memory. The presence of the stamped product and the resultant scrap are noted and similar signals generated. The output signals are also fed to memories. The movement of the press ram is monitored by means of sensor detecting rotation of the main press crankshaft. This sensor generates a timing signal and a fault check signal. If the stock is not present at one location during a predetermined time period, a fault check system signals the press to stop since it is an indication that stock is presumably jammed or backed up. After a fault check signal is generated and no fault signal is present, all input memories are reset and a new cycle is started.

Claims

1. An apparatus for protecting automatically a cyclical machine from damage due to jamming, the machine having an input for unprocessed stock and at least one output for processed stock comprising:

an input sensor which detects the presence of the unprocessed stock and generates a first electrical impulse in response thereto;

an output sensor which detects the presence of the processed stock and generates a second electrical impulse in response thereto;

timing means to coordinate the comparison of the first and second electrical impulses with the cycles of the machine;

means for comparing the first and second electrical impulses for a given piece of stock to determine that it is continuously moving through the machine and that the machine has not jammed, the means for comparing being operatively connected to the input sensor, output sensor and timing means;

means for stopping the machine if the means for comparing does not generate a proper signal, the means for stopping being operatively connected to the means for comparing.

2. The apparatus of claim 1 wherein the timing means is a sensor which detects each cycle of the machine and generates an electrical impulse in response thereto.

3. The apparatus of claim 2 wherein the means for comparing includes a press cycle shift memory which holds the first electrical impulse during a predetermined number of cycles of the machine.

4. The apparatus of claim 3 wherein the means for comparing further includes a comparison circuit which receives and compares the first electrical impulse and second electrical impulse to determine if processed stock is located at the output after a predetermined number of cycles after stock has been detected at the input.

5. The apparatus of claim 4 wherein the means for stopping further includes a fault check circuit operatively connected to the comparison circuit which signals when metal is not present at the output of the machine when it is present at the input.

6. The apparatus of claim 5 wherein the cycle memory includes a press cycle shift register which is at least a two-bit memory circuit.

7. The apparatus of claim 6 wherein the means for comparing further includes means for converting the first and second electrical impulses to logic signals so that the signals may be stored in the memory circuit.

8. The apparatus of claim 7 wherein the timing means is a proximity sensor which generates a signal to the fault check and advances the press cycle shift register.

9. The apparatus of claim 8 wherein the means for comparing further includes a one-bit memory circuit operatively connected to the press cycle shift register, which stores the first electrical impulse for one cycle.

10. The apparatus of claim 9 wherein the machine is a press die having a ram which cooperates with a complementary die block to punch sections out of the stock which is metal.

11. The apparatus of claim 10 wherein the input and output sensors are proximity sensors which detect metal.

12. The apparatus of claim 11 wherein a second output sensor is utilized to detect scrap metal after processing, the second output sensor generating a third electrical impulse, a second one-bit memory for storing the third electrical impulse until it is compared with the first electrical impulse;

a second comparison circuit which is operatively connected to and receives signals from the one-bit memory and the press cycle shift register.

13. A process for protecting automatically a cyclical machine which processes unprocessed stock having an input of unprocessed stock and at least one output of processed stock comprising:

sensing the presence of the unprocessed stock before entering the machine with a first sensor;

generating a first signal if stock is present;

storing the first signal in a memory;

monitoring the machine cycle;

sensing the presence of stock after it has been processed with a second sensor;

generating a second signal from the second sensor after a predetermined number of cycles;

comparing the signals from the first sensor and second sensor to determine the presence of input stock and processed stock in order to determine that stock is continuously moving through the machine and the machine has not jammed;

stopping the machine if the proper electrical impulses are not generated by the first and second sensor.

14. The process for protecting the machine of claim 13 further comprising sensing the presence of unprocessed stock with a proximity sensor having a field which is sensitive to the presence of the stock which is metal.

15. The process for protecting the machine of claim 14 further comprising sensing the presence of processed stock with a proximity sensor having a field which is sensitive to the presence of the processed stock.

16. The process of protecting the machine of claim 15 wherein processing the stock includes stamping a piece of metal out of a strip.

17. The process of protecting the machine of claim 16 which further includes sensing the presence of remaining scrap metal with a proximity sensor generating a signal and comparing it with the signal from the input sensor after a predetermined number of cycles.