GB2264705A - A method of preparing and processing of propellants - Google Patents
A method of preparing and processing of propellants Download PDFInfo
- Publication number
- GB2264705A GB2264705A GB9223360A GB9223360A GB2264705A GB 2264705 A GB2264705 A GB 2264705A GB 9223360 A GB9223360 A GB 9223360A GB 9223360 A GB9223360 A GB 9223360A GB 2264705 A GB2264705 A GB 2264705A
- Authority
- GB
- United Kingdom
- Prior art keywords
- components
- propellant charge
- mixed
- mixing
- vessel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000003380 propellant Substances 0.000 title claims description 49
- 238000000034 method Methods 0.000 title claims description 31
- 238000012545 processing Methods 0.000 title description 5
- 238000002156 mixing Methods 0.000 claims description 32
- 239000000203 mixture Substances 0.000 claims description 32
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- PXIPVTKHYLBLMZ-UHFFFAOYSA-N Sodium azide Chemical compound [Na+].[N-]=[N+]=[N-] PXIPVTKHYLBLMZ-UHFFFAOYSA-N 0.000 claims description 12
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 12
- 239000008188 pellet Substances 0.000 claims description 8
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 6
- 235000010333 potassium nitrate Nutrition 0.000 claims description 6
- 239000004323 potassium nitrate Substances 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- 238000013019 agitation Methods 0.000 claims description 3
- 235000012431 wafers Nutrition 0.000 claims description 3
- 238000004880 explosion Methods 0.000 claims description 2
- 238000007789 sealing Methods 0.000 claims description 2
- 238000003860 storage Methods 0.000 claims description 2
- 239000000470 constituent Substances 0.000 description 3
- 239000002360 explosive Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000005453 pelletization Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229940009868 aluminum magnesium silicate Drugs 0.000 description 1
- 150000001540 azides Chemical class 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 239000000391 magnesium silicate Substances 0.000 description 1
- 229910052919 magnesium silicate Inorganic materials 0.000 description 1
- 235000019792 magnesium silicate Nutrition 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000032258 transport Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B35/00—Compositions containing a metal azide
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B21/00—Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
- C06B21/0008—Compounding the ingredient
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Air Bags (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
- Medicinal Preparation (AREA)
Description
2264705 1 A METHOD OF PREPARING AND PROCESSING OF PROPELLANTS This
invention relates to a method for processing propellant charges suitable for use in, among other things, the gas generating component of air bag systems.
In conventional propellant processing techniques, components of the blend are weighed, transported into a discreet mixer, and. mixed together in V blenders or screw blenders and then transported to pressing operations. These blenders contain moving parts. For example, a screw blender is depicted in Figure 3. Materials enter a conical portion and are mixed by means of a. screw (4) which rotates about an axis (a) and further pivots (b) around the interior wall of the cone. The mixed materials enter a conduit (6) which may contain a second screw (8) which rotates on an axis (c) in order to create a transporting action which transports 1Che blended contents through to the exit.
While such blenders give good mixing of components, moving parts such as screws create a grave risk of danger. The combining of otherwise safe-tohandle components into an explosive mixture requires the exercise of caution and care to the highest degree. Contact o-LE the explosive mixture with moving parts, such as screws, creates a risk of generating heat or pressure caused by friction or mechanical contact. Such heat or pressure can set off the explosive charge. Such risks are hardly theoretical or far fetched, as such accidents have recently occurred at propellant manufacturing plants.
It is believed that tumbling mixing devices have been used in other industries, such as in the preparation and manufacture of pharmaceuticals. However, no analogous techniques have been employed in the propellant manufacturing industries, where the nature of the materials demand uncompromising devotion to the development of safer preparation techniques.
The -oresent invention seeks to provide a method of preparing propellant charges wherein the risks inherent to mixing the components of the propellant are minimised.
2 The invention f urther seeks to provide a method f or mixing propellant charges wherein no contact occurs between internal moving parts of the mixing apparatus and the propellant composition to be mixed.
According to the present invention there is provided a method for preparing propellant charge composition wherein the components of the charge are mixed in a manner eliminating contact of the charge components with internal moving parts to thereby reduce the risk of unintentional fire and explosion, said method being comprised of the steps of:
a) selecting propellant charge; b) placing the components within a mixing vessel which does not contain any internal moving parts; components suitable for forming a c) sealing the vessel; d) agitating the contents of the vessel for a preselected period of time and rate of agitation in order to mix the contents of the vessel to f orm a mixed propellant charge composition.
The invention is a method for preparing propellant charges which utilises a mixing step not heretofore utilised in this field of art. The individual propellant components are brought together in a closed container, usually metal. The closed container is tumbled in order to ef f ect the mixing of the propellant charge components. The mixed components can then be transported, still within the sealed container, to the site of a pelletising operation. Thus, the method also provides a means for containerising, transporting and storing the components within the very same mixing container.
By utilising this method of mixing, wherein the propellant mixture is devoid of contact with internal moving parts while mixed, the risks of generating explosioncreating friction, heat, or pressure is reduced to near zero. This provides a much safer means for producing propellant charges.
3 An embodiment of the invention will now be described by way of example with reference to the drawings, in which:- Figure 1 is a flow diagram of the process of the present invention.
Figure 2 is a graph depicting the pressure-time variation for the combustion of pellets or other consolidation propellant produced in accordance with this invention.
Figure 3 is an example of the prior art.
The invention shall be described with respect to an air bag propellant composition comprised of sodium azide, potassium nitrate, silicon dioxide, aluminum oxide, and magnesium silicate (a/k/a magnesol). All percentages used herein refer to weight percents.
A preblend consisting of potassium nitrate, aluminum oxide and magnesol are drum mixed in a suitable drum mixer. (Not shown).
Generally, the preblend is comprised of 17% to 19% potassium nitrate, up to 1% aluminum oxide, and up to 1% nagnesol, with these percentages referring to the weight percentage of each component in the final mixed propellant charge. The mixed preblend will eventually be blended with other constituents and is set aside until they are combined with other blend components at 14.
It is Preferred that the sodium azide of the mixed propellant charge have a particle size of 20 microns or smaller. It may thus be necessary to grind the particles. A suitable comminutor (10) is the Fitzmill, available from the Fitzpatrick Company of Elmhurst, Illinois. To achieve the desired grinding for particles having an initial size of 60 to 100 microns, we have found that this comminutor should be operated at a feed rate of 60 to 70 kg/hr, a hammer speed of 4,000 to 4,500 rpm, and a mesh size of 40 to 80 mesh. The relative humidity in the comminutor environment should not exceed 70%. A sufficient amount of sodium azide is weighed out at 12 to comprise 62% to 64% of the total blend. After grinding and weighing the azide should be transferred 4 to a tote bin 14, which is the closed container that serves as the eventual vessel wherein all components are mixed.
A suitable amount of silicon dioxide is weighed out and stored separately. Silicon dioxide generally comprises 17% to 19% of the blend.
The propellant blend constituents are added to the tote bin to comprise the unmixed propellant composition. The tote bin is closed to seal it from the external environment. The bit is brought to the blending apparatus (16). A suitable blending apparatus is available from Custom Metal Craft, Inc. of Springfield, Y10. Such an apparatus possesses means for gripping the exterior of the tote bin, such means being annexed to rotational means which rotates the gripped tote bin. The rotation of the tote bin serves to mix the components of the propellant composition. Mixing is absent any moving internal Parts which contact the composition. Mixing occurs in a sealed environment. Thus the risk of combustion of the propellant charge is substantially reduced since the possibility of creating friction, hea-L or pressure during mixing is virtually non- existent.
The blending apparatus should be operated at a rotation rate and duration calculated to achieve the desired blending of the constituents of the propellant composition. Since blending occurs by tumbling it is important that the tote bin not be filled to or near capacity with propellant charge since adequate mixing will not occur. It has been found that volumes below 75% of capacity give sufficient mixing. For the above described propellant charge, we have found that mixtures of components totalling 200 lbs are well mixed at the above parameters in tote bins having an interior volume of 12 ft3.
After blending, the mixed propellants can be transported and stored in the tote bin until the time of pelletisation. Thus, the tote bin functions as a suitable storage vessel.
The tote bin has a valve on the bottom so that when the bin is taken to the pelletising operation, it can be elevated above the pelletising presses and the valve opened to allow gravity feed of blended propellant to the press.
This mixing process has been applied in the embodiment depicted in Figure I for mixing propellant and consolidating it into propellant tablet for use, e.g., in automotive airbag inflators. It should be noted that this process is equally suitable for preparing and transporting propellant mixes to be consolidated into other forms such as discs or wafers.
A suitable pelletiser 18 is the Coulton Press available from the Vector Corp., Marion, Iowa. Pelletisation offers control of shape and weight of the propellant permitting use of a compact shape in airbag inflator systems.
In forming pellets, the pelletiser should be operated to apply a compacting force of 1.5 to 2.5 tons. The press can be operated to produce 300 to 350 pellets/minute (i.e.: 20 to 22 rpm). Pellets so produced will be 6 to 8 mm. in diameter. such pellets are suitable for incorporation in the assembled propellant cup of an automobile air bag system performed at assembly station 20.
The following example is illustrative of the mixing process disclosed herein. It should be noted that the process is suitable for other blend formulations and the eventual processing of a blend into other forms such as disks and wafers.
A propellant charge in the form of pellets was producing according to the manner described above. The pellets were comprised of 63% sodium azide, 19% preblend mixture (17% potassium nitrate, 1% aluminum oxide, and 1% magnesol), and 18% silicon dioxide.
Tests were conducted in a static pressure tank.
The composition was fired in order to determine pressure-time variation. The propellant exhibited a pressure-time variation of 1.329083 PSI/MS, a pressure at 20 millisecond of 15.881544 PSI, Pmax of 29.578682 PSI at 60. 59998 MS. Results are depicted in figure 2.
6
Claims (12)
1. A method f or preparing propellant charge composition wherein the components of the charge are mixed in a manner eliminating contact of the charge components with internal moving parts to thereby reduce the risk of unintentional f ire and explosion, said method being comprised of the steps of:
a) selecting propellant charge; b) placing the components within a mixing vessel which does not contain any internal moving parts; c) sealing the vessel; d) agitating the contents of the vessel for a preselected period of tine and rate of agitation in order to mix the contents of the vessel to form a mixed propellant charge composition.
components suitable for forming a
2. The method as set forth in claim 1 wherein the mixed propellant charge composition is pelletised in order to form pellets of the mixed propellant charge composition.
3. The method as set f orth in claim 1 wherein the mixed propellant charge composition is pelletised in order to form disks of the mixed propellant charge composition.
4. The method as set forth in claim 1 wherein the mixed propellant charge composition is pelletised in order to form wafers of the mixed propellant charge composition.
5. The method according to claim 2, 3 or 4 wherein the components of the charge are comprised of sodium azide, potassium nitrate, aluminum oxide, silicon dioxide, and magnesol.
6. The method according to claim 5 wherein the components of the charge are present in the following weight percent 7 ratios: 62 to 64% sodium azide; 17 to 19% potassium nitrate; 0 to 1% aluminum oxide 0 to 1% magnesol 17 to 19% silicon dioxide.
7. The method according to any one of claims 1 to 6 wherein at least one of the components are comminuted prior to mixing.
8. The method according to any one of claims 1 to 7 wherein the mixing vessel is a tote bin.
9. The method according to any one of claims 1 to 8 wherein agitation is effected by tumbling the mixing vessel.
10. The method according to any one of claims 1 to 9 wherein the mixing vessel is usable for movement, storage and feeding of the propellant mix into a consolidating apparatus.
11. The method according to any one of claims 1 to 10 wherein the mixing vessel is sealable to enable an inert atmosphere to be provided within the interior of the mixing vessel.
12. A method for mixing a propellant charge composition substantially as described herein with reference to and as illustrated in Figures 1 and 2 of the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84569192A | 1992-03-04 | 1992-03-04 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9223360D0 GB9223360D0 (en) | 1992-12-23 |
| GB2264705A true GB2264705A (en) | 1993-09-08 |
Family
ID=25295860
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9223360A Withdrawn GB2264705A (en) | 1992-03-04 | 1992-11-06 | A method of preparing and processing of propellants |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPH067668A (en) |
| CA (1) | CA2082007A1 (en) |
| DE (1) | DE4241902A1 (en) |
| FR (1) | FR2690152B1 (en) |
| GB (1) | GB2264705A (en) |
| IT (1) | IT1261049B (en) |
| SE (1) | SE9203416L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2740588C1 (en) * | 2020-08-11 | 2021-01-15 | Акционерное общество "Федеральный научно-производственный центр "Алтай" | Method of making an article from explosive composition |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4681975B2 (en) | 2005-08-04 | 2011-05-11 | 株式会社リコー | Image processing apparatus, image processing method, image processing program, and recording medium on which the program is recorded |
| RU2716123C9 (en) * | 2019-07-15 | 2021-05-25 | Акционерное общество "Федеральный научно-производственный центр "Алтай" | Complex for mixing components of explosive composition and molding articles therefrom |
| RU2716124C9 (en) * | 2019-10-09 | 2021-05-25 | Акционерное общество "Федеральный научно-производственный центр "Алтай" | Complex for mixing components of explosive composition and molding articles therefrom |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3937405A (en) * | 1973-12-18 | 1976-02-10 | Fluid Energy Processing And Equipment Company | Apparatus for mixing pulverizing and grinding black powder |
| US4461660A (en) * | 1982-06-21 | 1984-07-24 | C-I-L Inc. | Bulk manufacture of emulsion explosives |
| GB2133784A (en) * | 1982-11-17 | 1984-08-01 | Aeci Ltd | Making emulsion explosives |
| GB2192619A (en) * | 1986-01-14 | 1988-01-20 | Secr Defence | A container |
| US5007973A (en) * | 1989-10-12 | 1991-04-16 | Atlas Powder Company | Multicomponent explosives |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3695953A (en) * | 1970-03-09 | 1972-10-03 | Sprengstoffwerk Schonebock Veb | Method for the production of explosives |
| US4077613A (en) * | 1973-01-05 | 1978-03-07 | William Wilson | Process container |
| US3936330A (en) * | 1973-08-08 | 1976-02-03 | The Dow Chemical Company | Composition and method for inflation of passive restraint systems |
| DE2407659A1 (en) * | 1974-02-18 | 1975-09-04 | Aerojet General Co | Non-toxic gas generating compsns - of solid reductant and oxidant, for e.g. gas bag inflation |
| FR2288721A1 (en) * | 1974-10-25 | 1976-05-21 | Thiokol Corp | Non-toxic non-corrosive gas generating compsn - comprising alk metal azide and anhyd chromic chloride |
| AU505690B2 (en) * | 1977-02-16 | 1979-11-29 | Levenson, M.K. | Gas generating compositions |
| US5089069A (en) * | 1990-06-22 | 1992-02-18 | Breed Automotive Technology, Inc. | Gas generating composition for air bags |
-
1992
- 1992-10-30 JP JP4293579A patent/JPH067668A/en not_active Withdrawn
- 1992-11-03 CA CA002082007A patent/CA2082007A1/en not_active Abandoned
- 1992-11-06 GB GB9223360A patent/GB2264705A/en not_active Withdrawn
- 1992-11-16 SE SE9203416A patent/SE9203416L/en not_active Application Discontinuation
- 1992-12-11 DE DE4241902A patent/DE4241902A1/de not_active Withdrawn
- 1992-12-30 FR FR9215939A patent/FR2690152B1/en not_active Expired - Fee Related
-
1993
- 1993-01-19 IT ITTO930026A patent/IT1261049B/en active IP Right Grant
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3937405A (en) * | 1973-12-18 | 1976-02-10 | Fluid Energy Processing And Equipment Company | Apparatus for mixing pulverizing and grinding black powder |
| US4461660A (en) * | 1982-06-21 | 1984-07-24 | C-I-L Inc. | Bulk manufacture of emulsion explosives |
| GB2133784A (en) * | 1982-11-17 | 1984-08-01 | Aeci Ltd | Making emulsion explosives |
| GB2192619A (en) * | 1986-01-14 | 1988-01-20 | Secr Defence | A container |
| US5007973A (en) * | 1989-10-12 | 1991-04-16 | Atlas Powder Company | Multicomponent explosives |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2740588C1 (en) * | 2020-08-11 | 2021-01-15 | Акционерное общество "Федеральный научно-производственный центр "Алтай" | Method of making an article from explosive composition |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2690152B1 (en) | 1995-06-30 |
| GB9223360D0 (en) | 1992-12-23 |
| CA2082007A1 (en) | 1993-09-05 |
| JPH067668A (en) | 1994-01-18 |
| DE4241902A1 (en) | 1993-09-09 |
| SE9203416D0 (en) | 1992-11-16 |
| IT1261049B (en) | 1996-05-08 |
| ITTO930026A0 (en) | 1993-01-19 |
| FR2690152A1 (en) | 1993-10-22 |
| ITTO930026A1 (en) | 1994-07-19 |
| SE9203416L (en) | 1993-09-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |