CA2082007A1 - Method of preparing and processing of propellants - Google Patents

Method of preparing and processing of propellants

Info

Publication number
CA2082007A1
CA2082007A1 CA002082007A CA2082007A CA2082007A1 CA 2082007 A1 CA2082007 A1 CA 2082007A1 CA 002082007 A CA002082007 A CA 002082007A CA 2082007 A CA2082007 A CA 2082007A CA 2082007 A1 CA2082007 A1 CA 2082007A1
Authority
CA
Canada
Prior art keywords
components
propellant charge
mixed
propellant
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.)
Abandoned
Application number
CA002082007A
Other languages
French (fr)
Inventor
James Burtelow
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Breed Automotive Technology Inc
Original Assignee
Breed Automotive Technology Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Breed Automotive Technology Inc filed Critical Breed Automotive Technology Inc
Publication of CA2082007A1 publication Critical patent/CA2082007A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C06EXPLOSIVES; MATCHES
    • C06BEXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B35/00Compositions containing a metal azide
    • CCHEMISTRY; METALLURGY
    • C06EXPLOSIVES; MATCHES
    • C06BEXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B21/00Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
    • C06B21/0008Compounding the ingredient

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Air Bags (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
  • Medicinal Preparation (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE

Disclosed herein is a novel method for preparing propellant charges suitable for use in, among other things, the gas generating component of an air bag system. In particular, the components of the propellants are blended in mixing vessels such as a tote bin which are tumbled in order to mix the components of the charge.
Tumbling is effected by tumbling mixer which contains no internal moving parts. The blended components are then pressed into pellets or other shapes to form the finished charge.

Description

BACKGROUND OF THE INVENTION

Disclosed herein is a novel method for processing propellant charges suitable for use in, amon~ other thin~s, the gas Qeneratin~q component of an air ba~
system. In particular, the components of the propellants are blended in a tumbling mixer which contains no internal movin~ parts. In addition, the propellant components remain safely enclosed in a sealed metal container from the point of blend formulation throu~h to feedin~ for the pellet pressing operation.
In conventional propellant processing techniques, components of the blend are weighed, transported into a discreet mixer, and mixed to~ether in V blenders or screw blenders and then transported to pressin~ operations. These blenders contain movin~ parts.
While such blenders ~ive ~ood mixinq of components, movin~ parts such as screws create a ~rave risk of dan~er. The combinin~ of otherwise safe-to-handle components into an explosive mixture requires the exercise of caution and care to the hi~hest de~ree. Contact of the explosive mixture with movin~ parts, such as screws, creates a risk of ~eneratin~ heat or pressure caused by friction or mechanical contact.
Such heat or pressure can set off the explosive char~e. Such risks are hardly theoretical or far fetched, as such accidents have recently occurred at propellant manufacturin~ plants.
It is believed that tumblin~ mixin~ devices have been used in other industries, such as in the preparation and manufacture of pharmaceuticals. However, no analo~ous techniques have been employed in the propellant manufacturing industries, where the nature of the materials demand uncompromisin~ devotion to the - 2 - 2~82û07 development of safer preparation techniques.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method of preparing propellant char~es wherein the risks inherent to mixin~ the components of the propellant are 5 minimized.
It is a further object of the invention to provide a method for mixing propellant char~es wherein no contact occurs between internal moving parts of the mixing apparatus and the propellant composition to be mixed.
Other objects shall become apparent from the invention disclosed below.
The invention is a method for preparing propellant char~es which utilizes a mixing step not heretofore utilized 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 effect the mixin~ of the propellant charge components. The mixed components can then be transported, still within the sealed 15 container, to the site of the pelletizin~ operation. Thus, the method also provides a means for containerizing, transporting and storin~ the components within the very same mixin~ container.
By utilizin~ this method of mixin~, wherein the propellant mixture is devoid of contact with internal movin~ parts while mixed, the risks of ~enerating 20 explosion-creatin~ friction, heat, or pressure is reduced to near zero. This provides a much safer means for producing propellant charges.

_ 3 _ 2082007 BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the invention will become apparent upon readin~ the followin~ detailed description and upon referring to the drawin~s in which:
FIGURE 1 is a flow dia~ram of the process of the present invention;
FIGURE 2 is a ~raph depictin~ the pressure-time variation for the combustion of pellets or other consolidation propellant produced in accordance with this invention; and FIGURE 3 is an example of the prior art.
While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED D~RIPTION OF THE PREFERRED EMBODIMENTS

A conventional screw blender is depicted in Fi~ure 3. Materials enter a conical portion and are mixed by means of a screw (4) which rotates about an axis (aJ
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 20 order to create a transporting action which transports the blended contents throu~h to the exit.

20820~7 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 (alk/a magnesol). All percentages used herein refer to wei~ht percents.
A preblend consisting of potassium nitrate, aluminum oxide and magnesol are drum mixed in suitable drum mixer (not shown).
Generally, the preblend is comprised of 17% to 19% potassium nitrate, up to 1% aluminum oxide, and up to 1.0 magnesol, with these percentages referring to the weight percenta~e 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 havin~ 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 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.

~ 5 ~ 2082007 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 bin is brought to the blending apparatus (16). A suitable blending apparatus is available from Custom Metal Craft, Inc. of Springfield, M0. Such anapparatus 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 creatin~ friction, heat 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 propellantcomposition. Since blendin~ occurs by tumbling, it is important that the tote bin not be filled to or near capacity with propellant char~e 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 Ibs. 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 pelletization. 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 the pelletizing operation, it can be elevated above the pelletizing 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 1 for mixing propellant and consolidating it into propellant tablet for use, e.~., in automotive air bag inflators. It should be noted that this process is equally suitable 5 for preparing and transporting propellant mixes to be consolidated into other forms such a disks or wafers.
A suitable pelletizer 18 is the Coulton Press available from the Vector Corp., Marion, lowa. Pelletization offers control of shape and weight of the propellant permittin~ use of a compact shape in air bag inflator systems.
In forming pellets, the pelletizer should be operated to apply a compactin~
force of 1.5 to 2.5 tonnes. 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.

2~82007 ~XAMPLE

A propellant charge in the form of pellets was produced accordiny to the manner described above. The pellets were comprised of 63% sodium azide, 19%
5 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 Fi~ure 2.

Thus it is apparent that there has been provided in accordance with the invention a method for preparing propellant char~e composition that fully satisfies the 15 objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in li~ht of the fore~oin~ description. Accordin~ly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention.

Claims (11)

1. 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 damages of unintentional fire and explosion, said method being comprised of the steps of:
(a) selecting components suitable for forming a propellant charge;
(b) placing the components within a mixing vessel which does not contain any internal moving parts;
(c) sealing the vessel; and (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 form a mixed propellant charge composition.
2. The method as set forth in claim 1 wherein the mixed propellant charge composition is pelletized in order to form pellets of the mixed propellant charge composition.
3. The method as set forth in claim 1 wherein the mixed propellant charge composition is pelletized 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 pelletized in order to form wafers of the mixed propellant charge composition.
5. The method according to claim 2 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 ratios:
62% to 64% - sodium azide;
17% to 19% - potassium nitrate;
0% to 1% - aluminum oxide;
0% to 1% - magnesol; and 17% to 19% - silicon dioxide.
7. The method according to claim 1 wherein at least one of the components are comminuted prior to mixing.
8. The method according to claim 1 wherein the mixing vessel is a tote bin.
9. The method according to claim 1 wherein agitation is effected by tumbling the mixing vessel.
10. The method according to claim 1 wherein the mixing vessel can be used for movement, storage and feeding propellant mix into a consolidating apparatus.
11. The method according to claim 1 wherein the mixing vessel can be sealed to effect an inert atmosphere within the interior of the mixing vessel.
CA002082007A 1992-03-04 1992-11-03 Method of preparing and processing of propellants Abandoned CA2082007A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US84569192A 1992-03-04 1992-03-04
US845,691 1992-03-04

Publications (1)

Publication Number Publication Date
CA2082007A1 true CA2082007A1 (en) 1993-09-05

Family

ID=25295860

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002082007A Abandoned CA2082007A1 (en) 1992-03-04 1992-11-03 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 (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2716124C1 (en) * 2019-10-09 2020-03-05 Акционерное общество "Федеральный научно-производственный центр "Алтай" Device for mixing components of explosive composition and molding articles therefrom
RU2716123C1 (en) * 2019-07-15 2020-03-05 Акционерное общество "Федеральный научно-производственный центр "Алтай" Device for mixing components of explosive composition and molding articles therefrom

Families Citing this family (2)

* Cited by examiner, † Cited by third party
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
RU2740588C1 (en) * 2020-08-11 2021-01-15 Акционерное общество "Федеральный научно-производственный центр "Алтай" Method of making an article from explosive composition

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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
US3937405A (en) * 1973-12-18 1976-02-10 Fluid Energy Processing And Equipment Company Apparatus for mixing pulverizing and grinding black powder
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
CA1181593A (en) * 1982-06-21 1985-01-29 William E. Cribb Bulk manufacture of emulsion explosives
US4491489A (en) * 1982-11-17 1985-01-01 Aeci Limited Method and means for making an explosive in the form of an emulsion
GB8600739D0 (en) * 1986-01-14 1986-02-19 Secr Defence Container
US5007973A (en) * 1989-10-12 1991-04-16 Atlas Powder Company Multicomponent explosives
US5089069A (en) * 1990-06-22 1992-02-18 Breed Automotive Technology, Inc. Gas generating composition for air bags

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2716123C1 (en) * 2019-07-15 2020-03-05 Акционерное общество "Федеральный научно-производственный центр "Алтай" Device for mixing components of explosive composition and molding articles therefrom
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
RU2716124C1 (en) * 2019-10-09 2020-03-05 Акционерное общество "Федеральный научно-производственный центр "Алтай" Device 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

Also Published As

Publication number Publication date
DE4241902A1 (en) 1993-09-09
SE9203416L (en) 1993-09-05
FR2690152B1 (en) 1995-06-30
ITTO930026A1 (en) 1994-07-19
IT1261049B (en) 1996-05-08
JPH067668A (en) 1994-01-18
ITTO930026A0 (en) 1993-01-19
GB9223360D0 (en) 1992-12-23
GB2264705A (en) 1993-09-08
FR2690152A1 (en) 1993-10-22
SE9203416D0 (en) 1992-11-16

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Legal Events

Date Code Title Description
FZDE Discontinued