Delay units and methods of making the same

• US 8,245,643 B2
• Filed: 11/20/2009
• Issued: 08/21/2012
• Est. Priority Date: 02/08/2005
• Status: Expired due to Fees

• Current Assignee: DYNO Nobel Incorporated (Incitec Pivot Limited)
• Original Assignee: DYNO Nobel Incorporated (Incitec Pivot Limited)
• Inventors: Childs, John, Shank, Lawrence J. III
• Primary Examiner(s): Carone, Michael
• Assistant Examiner(s): Abdosh, Samir
• Application Number:
  US12/622,993
• Publication Number:
  US 20100064924A1
• Time in Patent Office: 1,005 Days
• Field of Search: 102/202.13, 102/275.3, 102276-2772, 102/269
• US Class Current: 102/276
• CPC Class Codes: F42C 9/10 the timing being caused by combustion F42C9/14 takes precedence

Abstract

A delay unit (10) comprises a timing strip (14) and, optionally, a calibration strip (20) deposited on a substrate (12). The timing and calibration strips comprise energetic materials which optionally may comprise particles of nanosize materials, e.g., a fuel and an oxidizer, optionally applied as separate layers. A method of making the delay units comprises depositing onto a substrate (12) a timing strip (14) having a starting point (14d) and a discharge point (14e) and depositing onto the same or another substrate a calibration strip (20). Timing strip (14) and calibration strip (20) are of identical composition and are otherwise configured, e.g., thickness of the strips, to have identical burn rates. The calibration strip (20) is ignited and its burn rate is ascertained. The timing strip (14) is adjusted by an adjustment structure to attain a desired delay period, preferably on the basis that the burn rate of the timing strip (14) is substantially identical to that of the calibration strip (20) and ascertaining the burn rate of the calibration strip. The adjustment may be attained by one or more of providing the timing strip with jump gaps (164), an accelerant or retardant (166a, 166b), completing the timing strip with a bridging strip (14c), or establishing a selected effective length of the timing strip by positioning one or both of a pick-up charge (16) and relay charge (18) over a portion of the timing strip.

Claims

1. A delay unit for imposing a time delay period in a sequence of reactions, the delay unit comprising a substrate having a surface, at least one timing strip disposed on the surface and having a starting point and a discharge point spaced apart from each other, the distance along the timing strip between the starting point and the discharge point defining the effective length of the timing strip, the timing strip comprising an energetic material which upon ignition at the starting point results in an energy-releasing reaction which travels along the timing strip to the discharge point, the duration of such travel determining the time delay period, and the effective length of the timing strip and the burn rate of the energetic material determining the duration of such travel, the energetic material being comprised of at least one discrete layer of a fuel and at least one discrete layer of an oxidizer, the layer of the fuel and the layer of the oxidizer contacting each other.

5. The delay unit of any one of claim 1, 2, 3 or 4 wherein the energetic material comprises nanosize particles of fuel and nanosize particles of oxidizer, the nanosize particles being present in an amount at least sufficient to impart to the energetic material a smaller critical diameter than that of an otherwise identical energetic material lacking such nanosize particles.

6. The delay unit of any one of claim 1, 2, 3 or 4 wherein one of the layer of the fuel and the layer of the oxidizer at least partly overlies the other.

7. The delay unit of claim 1 further comprising a pick-up charge in signal transfer communication with the starting point of the timing strip and a relay charge in signal transfer communication with the discharge point of the timing strip, both the pick-up charge and the relay charge being deposited on the same surface as the timing strip.

8. The delay unit of claim 1 further comprising at least one of (a) a pick-up charge in signal transfer communication with the starting point of the timing strip, and (b) a relay charge in signal transfer communication with the discharge point of the timing strip, and wherein at least one of the charges is placed at an intermediate location along the length of the timing strip whereby the effective length of the timing strip is determined by placement of the charge or charges.

9. The delay unit of claim 8 wherein both the pick-up charge and the relay charge are present and at least one of the charges is placed at an intermediate location along the length of the timing strip.

10. The delay unit of claim 1 further comprising a pick-up charge spaced from a relay charge and a plurality of the timing strips connected in signal transfer communication at one end of the timing strips to the pick-up charge and at the other end of the timing strips to the relay charge, to provide redundant timing strips to initiate the relay charge.

11. The delay unit of claim 10 wherein the timing strip has a first bus area at its starting point and a second bus area at its discharge point, the first bus area being in signal transfer communication with the pick-up charge and the second bus area being in signal transfer communication with the relay charge.

13. The delay unit of claim 1 wherein the oxidizer comprises TiO₂.

15. The delay unit of claim 1 wherein the energetic material comprises nanosize particles of fuel M′

and oxidant MyOx wherein M′ and

M are the same or different metals and y and x may be the same or different positive integers 1, 2, 3 . . . n.

16. The delay unit of claim 15 wherein M′

and M are selected from one or more of Ag, Al, B, Cu, Hf, Si, Sn, Ta, W, Y and Zr.

17. The delay unit of claim 15 wherein M′

and M are selected from one or more of Al, Cu and Ag.

27. The delay unit of claim 1 wherein the surface of the substrate comprises a reactive surface.

2. A delay unit comprising a substrate having deposited thereon at least one timing strip having a starting point and a discharge point spaced apart from each other, the distance along the timing strip between the starting point and the discharge point defining the effective length of the timing strip, the timing strip comprising an energetic material capable of conducting an energy-releasing reaction therealong, the energetic material being selected from the class consisting of a fuel and an oxidizer and wherein the energetic material is comprised of at least one discrete layer of the fuel and at least one discrete layer of the oxidizer, the layer of the fuel and the layer of the oxidizer contacting each other, and wherein the timing strip comprises a first strip having a terminal gap, and a bridging strip connecting the first strip to close the terminal gap, the first and bridging strips cooperating to define the effective length of the timing strip between the starting point and the discharge point.

3. The delay unit of claim 2 wherein the timing strip further comprises a second strip, the second strip being separated from the first strip by the terminal gap and the bridging strip connects the first strip to the second strip.

24. The delay unit of claim 2 wherein the timing strip has a terminal gap between the starting point and the discharge point, and a bridging strip which closes the terminal gap to complete connection by the timing strip of the starting point to the discharge point.

25. The delay unit of claim 2 further comprising a pick-up charge spaced from a relay charge and a plurality of the timing strips connected in signal transfer communication at one end of the timing strips to the pick-up charge and at the other end of the timing strips to the relay charge, to provide redundant timing strips to initiate the relay charge, the timing strip having a first bus area at its starting point and a second bus area at its discharge point, the first bus area being in signal transfer communication with the pick-up charge and the second bus area being in signal transfer communication with the relay charge.

26. The delay unit of claim 25 wherein the second bus area is enlarged relative to the timing strips whereby the energy released at the second bus area is greater than the energy released along the timing strip.

28. The delay unit of claim 2 wherein the surface of the substrate comprises a reactive surface.

29. The delay unit of claim 2 wherein the oxidizer comprises TiO₂.

4. A delay unit comprising a substrate having deposited thereon at least one timing strip having a starting point and a discharge point spaced apart from each other, the distance along the timing strip between the starting point and the discharge point defining the effective length of the timing strip, the timing strip comprising an energetic material capable of conducting an energy-releasing reaction therealong, the energetic material being selected from the class consisting of a fuel and an oxidizer and wherein the energetic material is comprised of at least one discrete layer of the fuel and at least one discrete layer of the oxidizer, the layer of the fuel and the layer of the oxidizer contacting each other, wherein the timing strip has a terminal gap between the starting point and the discharge point, and a bridging strip which closes the terminal gap to complete connection by the timing strip of the starting point to the discharge point.

12. A delay unit comprising a substrate having deposited thereon at least one timing strip having a starting point and a discharge point spaced apart from each other, the distance along the timing strip between the starting point and the discharge point defining the effective length of the timing strip, the timing strip comprising an energetic material capable of conducting an energy-releasing reaction, the energetic material being selected from the class consisting of a fuel and an oxidizer and wherein the energetic material is comprised of at least one discrete layer of the fuel and at least one discrete layer of the oxidizer, the layer of the fuel and the layer of the oxidizer contacting each other, a pick-up charge spaced from a relay charge and a plurality of the timing strips connected in signal transfer communication at one end of the timing strips to the pick-up charge and at the other end of the timing strips to the relay charge, to provide redundant timing strips to initiate the relay charge, wherein the timing strip has a first bus area at its starting point and a second bus area at its discharge point, the first bus area being in signal transfer communication with the pick-up charge and the second bus area being in signal transfer communication with the relay charge and the second bus area is enlarged relative to the timing strips whereby the energy released at the second bus area is greater than the energy released along the timing strip.

14. A delay unit comprising a substrate having deposited thereon at least one timing strip having a starting point and a discharge point spaced apart from each other, the distance along the timing strip between the starting point and the discharge point defining the effective length of the timing strip, the timing strip comprising an energetic material capable of conducting an energy-releasing reaction therealong, the energetic material being selected from the class consisting of a fuel and an oxidizer and wherein the energetic material is comprised of at least one discrete layer of the fuel and at least one discrete layer of the oxidizer, the layer of the fuel and the layer of the oxidizer contacting each other, and wherein the timing strip comprises an adjustment structure selected from the class consisting of one or more jump gaps, one or more accelerants and one or more retardants.

18. A delay unit comprising a substrate having deposited thereon at least one timing strip having a starting point and a discharge point spaced apart from each other, the distance along the timing strip between the starting point and the discharge point defining the effective length of the timing strip, the timing strip comprising an energetic material capable of conducting an energy-releasing reaction therealong, the energetic material being selected from the class consisting of a fuel and an oxidizer and wherein the energetic material is comprised of at least one discrete layer of the fuel and at least one discrete layer of the oxidizer, the layer of the fuel and the layer of the oxidizer contacting each other, and wherein the timing strip is comprised of a major portion and a minor portion, the major portion having an effective length greater than that of the minor portion and the minor portion having a burn rate greater than that of the major portion, the disparity in the respective lengths and burn rates of the major and minor portions being great enough that the burn time of the minor portion is negligible compared to the burn time of the major portion so that the delay period of the delay unit is substantially determined by the burn time of the major portion.

19. A method of making a delay unit comprising depositing onto a substrate a timing strip having a starting point and a discharge point, the timing strip comprising an energetic material comprised of a fuel and an oxidizer, the fuel and the oxidizer being applied separately to the substrate as at least one discrete layer of fuel and at least one discrete layer of oxidizer, which layers contact each other on the substrate, the method further comprising depositing on the substrate a calibration strip of energetic material separated from the timing strip sufficiently to preclude ignition of the timing strip by ignition of the calibration strip.

20. The method of claim 19 wherein the energetic material of the calibration strip is substantially the same as the energetic material of the timing strip.

21. The method of claim 19 wherein the energetic material comprises nanosize particles of fuel M′

and oxidant MyOx wherein M′ and

M are the same or different metals and y and x may be the same or different positive integers 1, 2, 3 . . . n.

22. The method of claim 21 wherein M′

and M are selected from one or more of Ag, Al, B, Cu, Hf, Si, Sn, Ta, W, Y and Zr.

23. The method of claim 21 wherein M′

and M are selected from one or more of Al, Cu and Ag.