US3588054A

US3588054A - Apparatus for kneading doughy explosives

Info

Publication number: US3588054A
Application number: US784340A
Authority: US
Inventors: Sten Herman Ljungberg; Bror Lennart Teodor Sternhoff
Original assignee: Nitro Nobel AB
Current assignee: Nitro Nobel AB
Priority date: 1967-12-27
Filing date: 1968-12-17
Publication date: 1971-06-28
Anticipated expiration: 1988-06-28
Also published as: NO120063B; JPS496090B1; FI46838B; BG15074A3; DE1814384A1; BR6805186D0; ZM18668A1; FI46838C; GB1253220A; SE329115B; CH513091A; FR1599422A; ES361599A1

Abstract

APPARATUS INCLUDING AN ELONGATED FLEXIBLE HOSE LOCATED WITHIN A CASING WHICH IS DIVIDED INTO A PLURALITY OF CHAMBERS AND INTO WHICH FULID UNDER PRESSURE IS SEQUENTIALLY INTRODUCED TO KNEAD DOUGHY MATERIAL AND CAUSE A PERISTALTIC ADVANCE OF SUCH MATERIAL THROUGH THE HOSE.

Description

0 United States Patent 11113,588,054

[72] lnventors Sten Herman Ljungberg; [50] Field of SearchWl 259/2, 4, l, Bror Lennart Teodor Sternhoff, 180, 150, 72, l8, I9, 36, 29 Vinterviken, Stockholm, Sweden 211 Appl. No, 784,340 1 References Cited [22] Filed Dec. 17, 1968 UNITED STATES PATENTS i 1 Palsmed g 28,1971 2,425,237 8/1947 Field 18/12 1 Asslenee Mm Nobel AB 3,460,809 8/1969 Hauss 259 4 32 2 1 52? 3,063,683 11/1962 Westbrook 259/2 P 't non y Swede Primary Examiner-Robert W Jenkins [3 I 1 17877 Alt0rneys-A. Yates Dowell and A. Yates Dowel], Jr.

[54] KNEADING DOUGHY ABSTRACT: Apparatus including an elongated flexible hose lo Claim 3D located within a casing which is divided into a plurality of "wing chambers and into which fluid under pressure is sequentially [52] U.S. Cl 259/4 introduced to knead doughy material and cause a peristaltic [51] Int. Cl BOlf 15/02 advance of such material through the hose.

PATENTED JUN28 IQYI SHEET 2 [IF 3 A T TOR Nt' Y5 PATENTEU JUN28 |97| 3, 588,054

sum 3 UP 3 Fig.3

AT ORNEYJ APPARATUS FOR KNEADING DOUGIIY EXFLOSWES This invention relates to an apparatus for kneading doughy explosives.

In methods actually in use now of intermixing or kneading together the components of doughy materials in general and explosives in particular to a homogeneous mass, apparatuses are used which constitute relatively great units charged with batches to be kneaded of an order of magnitude exceeding 200 kilograms per unit, for example. The intermixing action is effected by means of mechanical members which, as experience has shown, when kneading of explosives is in question can under unfavorable conditions cause an initiation or priming of the explosive which in spite of scrupulous safety measures result in serious damages and even loss of human lives.

The invention starts from a known structure comprising a hose of resilient material housed within a rigid longish casing.

One main object of the invention is to provide an apparatus based on said known structure which while being formed without mechanical treating members has so simple a shape that it to advantage can be built and used in series in which each apparatus is operated with relatively small quantities of the explosive, such as 10 kilograms, for example, and is easy to insulate from adjacent apparatuses in the series so that a sequence of reactions practically is impossible if for some reason the explosive in one apparatus should be brought to detonate.

According to one main feature of the invention the hose extending from an inlet space to a discharge end is in sections surrounded by chambers which are in connection with a pressure fluid source and disposed to become actuated by the pressure fluid in a predetermined sequence in such a manner that a peristaltic advance movement is brought about in the hose.

Further objects and advantages of the invention will become apparent from the following description considered in connection with the accompanying drawings, which form part of this specification, and of which:

FIG. I is a partial sectional perspective view of a portion of an apparatus constructed according to the invention and of a closing device presented in a reduced scale of an inlet chamber forming part of the apparatus.

FIG. 2 illustrates in three diagrammatic, longitudinally sectional views of the apparatus three different advancing steps in the treatment of a mass of explosive within the apparatus.

FIG. 3 is a diagrammatic and partially longitudinal sectional view of a modified embodiment of the invention.

Referring to the drawings and in particular FIGS. 1 and 2, reference numeral 10 denotes a hose of resilient material, such as for example artificial plastic or synthetic rubber, which hose uninterrupted extends within a series of .stay tubes 12 arranged in sequence the one releasably connected with the other. These stay tubes 12 are preferably of some rigid plastic or light metal. Each stay tube is at its ends provided with an outwardly projecting annular flange M which is passed by fastening bolts 16 distributed in a suitable even number close to the circumference (FIG. 1).

Between each stay tube 12 and the hose l passing therethrough the tube receives a tubular piece 18 consisting of some resilient material, such as synthetic rubber, for example. The wall thickness of said tubular piece increases from a middle portion 20 towards each end, where the tubular piece is formed with an outwardly projecting annular flange 22 bulging axially into a broader portion or collar 24 extending around the outer circumference of said end flange 22. The annular flanges 22 and their collars 24 are received in annular grooves 26 of corresponding shape formed in each of the averted faces of the end flanges 14 of each stay tube 12. Thus in each connection between adjacent stay tubes I2 two end flanges 22 facing one another of the tubular pieces 18 en closed by said said stay tubes are retained firmly interconnected in a sealing manner so as to form a continuous channel for the hose located within said tubular pieces.

In one of the two annular flanges 14 of each of the stay tubes 12 a channel 28 is formed which opens into the interspace between the tube 12 and the appertaining resilient tubular piece 18 and in outward direction opens into a radial bore 30 provided with inner threads to receive a nipple 32 formed with corresponding outer threads for attaching a tube leading to a programmed pressure fluid source not shown in the drawings. The term pressure fluid source is here understood to include connecting conduits and valves controlling said conduits. The programming is of such kind that the pressure fluid is supplied in a predetermined sequence to the inwardly expansible pressure chambers denoted 36, 38, 40 42, 44, 46, 48, 50, 52 and 54in FIG. 2 and formed between the stay tubes 12 and the tubular pieces 18 in such a manner that a peristaltic advancing movement can be produced within the tube 10.

The uppermost stay tube 12 is provided with a cover 56 passed by two tubes 58 for supply of respectively a dry and a moist or liquid phase of the components of the composition of explosive intended to be intermixed in the apparatus. In addition, said uppermost tube 12 may be provided with a closing device for the enclosed pressure chamber 36. In the embodiment shown this device comprises two cylinders 60 attached to the stay tube diametrically opposed locations and each containing a piston 62 with piston rod 64 which latter from opposite directions project into the stay tube so as to be capable to seal with their free ends formed with suitable clamping end faces the chamber 36 below the supply tubes 58 when pressure fluid is fed to the cylinders 60 through tubular conduits 66.

The lowermost support tube 54 (FIG. 2) is connected to a discharge head 68 through which the treated mass 70 is delivered in a continuous strand to a diagrammatically in dicated belt conveyor 72, for example, to be conveyed further to a packeting device not shown.

How a kneading operation can be carried out when making use of the apparatus described above, is illustrated for three subsequent steps represented in FIG. 2 from left to right hand.

In the first step the ingredients or components are being fed from the tubes 58 into that portion of the hose 10 which is on the same level as the pressure chamber 38 and which in the present case forms the inlet space mentioned hereinbefore. The

subsequent chambers

40, 42 are pressure-loaded and thus closed. In the closing step which implies that the middle portion 20 of the chamber walls are pressed against one another a small space is left open in the hose 10 at the transition zone between the

chambers

40, 42. Said space is filled with a part 74 of a batch 76 fed downwards from a preceding feeding operation not shown through the sections of the hose 10 between the

chambers

40, 42 the main part of which batch is shown in the level of the unloaded pressure chamber 44. The two

chambers

46, 48 following in sequence are closed and the next following one, the chamber 50, is relieved of pressure and the corresponding hose section filled with still another batch 78 under downwards directed movement and with a minor portion 80 left behind in the space between the

chambers

46, 48 within the hose 10, i.e. a formation of feeding corresponding to that described above for the

batch

74, 76. A similar for mation is again shown in connection with the

chambers

52, 54 with the modification, however, that the main portion'shown here of the batch 70 is on its way out of the apparatus to be deposited on the belt conveyor 72.

In the next following step illustrated in the middle portion of FIG. 2, the uppermost chamber 36 has been loaded with pressure and the inlet section of the hose 10 at the level of the chamber 38 which was being filled in the first step, has been closed around a new batch 82.

The third step illustrated in FIG. 2 most at right hand implies that also the next uppermost pressure chamber 38 has been closed. Simultaneously, the chamber 40 has been relieved of pressure, the chamber 44 has been loaded with, the chamber 46 has been relieved of, the chamber 50 has been loaded with, and the chamber 52 has been relieved of, pressure. I

The mass under the kneading treatment advanced in a peristaltic movement in the formation comprising a minor remainder such as 74, for example, and a main portion, such as 76 for example, is thus displaced after the introductory filling step continuously downwards over the length of one pressure chamber towards the discharge head 68.

The number shown in the embodiment of FIG. 2 of pressure chambers and the length of the hose l determined thereby can be varied, as is easily understood, in response to the intensity of kneading treatment required for the components constituting the mass to be intermixed in order to give a desired result. By varying the sequence of closing and opening actions as well as the pressure in the chambers a remaining portion, such as 74, or even a reflux of the mass achieved in this way can improve the kneading effect while reducing the advance of feed in a corresponding degree.

The mass to be treated may, of course, have highly varying plasticity which may change the formation of the mass as shown in FIG. 2, which means the form taken by the pressure chambers when loaded with the pressure fluid. This form will have some influence on the capacity of the apparatus to bring about during the kneading operation the complete intermixture of or correct distribution of the ingredients forming part of the mass. One method of influencing said shape so as to at tain a satisfying result is to balance the length of the stay tubes 12 and therewith the pressure chambers against their inner diameter in a suitable manner. It has been found that the length of the stay tube ought to be 1.5 to 2 times the diameter, the length having to be the shorter, the drier the mass is which is to be treated.

In the embodiment of the apparatus of the invention shown in FIG. 2 the uppermost chamber 36 serves as closing means for the inlet chamber. This closure may be replaced by the device described earlier and shown in reduced scale uppermost in FIG. 1.

The apparatus described above are intended in the production of explosives to be disposed in series laterally of one another with such spacing therebetween and separated from one another by protective means of such kind that no sequence of reactions must be apprehended if for some other reason the mass to be treated in one of the apparatus would detonate.

The various apparatus in the series thus contemplated are intended to be fed from a common feeding aggregate.

A plant with a number of kneading apparatuses according to the invention can be remote-controlled from a common programming unit which is located at a place sage from explosions.

The kneading effect can be intensified by having the peristaltic advancing movement effected against a counterpressure. This implies that the relief of pressure in a pressure chamber is not carried down to atmospheric pressure but only to some predetermined superatmospheric pressure which may amount to one or several few tenths of the full working pressure of the pressure fluid'source. In the embodiment shown in FIG. 3 the discharge conduits 34 from the

chambers

42, 44, 46, 48, 50, 52 and 54 are connected to a common container 84 within which a superatmospheric pressure is maintained in order to obtain the contemplated counterpressure in said chambers. The relief of pressure in the chambers is thus not effected to atmospheric pressure but to the superatmospheric pressure prevailing in the container 84. This pressure is adjusted to a desired value by means of a counterpressure valve 88 provided in an outlet 86 from the container 84. lnserted in the conduits 34 are valves 90 of two-way type which also are connected to branch conduits 92 from a common supply conduit 94 leading from the pressure fluid source, which may contain compressed air. By resetting the valves 90 the chambers 42 to 54 are alternately connected with the pressure conduit 94 and the pressure container 84. When thus, for example, the content of the batch of explosive 76 enclosed by the chamber 44 is to be pressed downwards into the portion of the hose enclosed by the chamber 46, the chamber 44 is connected to the pressure fluid conduit 94 whereas the valve of the chamber 46 is readjusted so that said chamber is connected to the pressure container 84. This results in that some pressure must be exerted on the resilient wall of the chamber 46 to enable the batch of explosive to penetrate down while forcing said wall outwards. In this manner the kneading of the batch during its downwards displacement becomes particularly effective.

Although all chambers may be connected with a counterpressure container the outlets 34 for the

chambers

36, 38 and 40 in the embodiment illustrated in FIG. 3 which are located nearest the the inlet of the apparatus, open into the ambient atmosphere. The valves 90 located in these outlets 34 thus connect the chambers either with the pressure conduit 94 or with the ambient atmosphere.

REference numeral 96 denotes a programming unit to which by means of signal wires 98 magnetic members 100 are connected for actuating the individual valves 90 in that sequence which is required for bringing about the peristaltic advance movement.

If desired, the inner coherent hose 10 may be dispensed with the doughy explosive during its passage through the apparatus having direct contact with the tubular pieces 18. This type of apparatus renders easier the return of the inner passage through the apparatus to its original volume after the peristaltic advance movements. In this connection it is possible to connect the chambers 40 to 54 with a source of vacuum so that their inner resilient walls quickly regain their initial position. If desired, a coherent hose can in its longitudinal direction be formed with cavities which form the chambers 40 to 54 connected with the pressure fluid source.

The counterpressure container 84 may be common for all chambers or the individual chambers, or groups of chambers may be connected to separate counterpressure containers. This is especially suitable when different counterpressure levels are to be created in different parts of the apparatus, such as a lower counterpressure in the chambers nearest the inlet than in the more remote chambers. The counterpressure can be produced by a throttling arrangement in the outlets 34 which not but after some response time relieves the chambers from pressure. The counterpressure may also be brought about by means of a back pressure valve of known type.

While several more or less specific embodiments of theinvention have been shown and described, it is to be understood that this is for purpose of illustration only, and that the invention is not to be limited'thereby, but its scope is to be determined by the appended claims.

We claim:

1. An apparatus for kneading doughy explosives, comprising a hose of resilient material disposed within a longish casing characterized in that the hose from an inlet space to a discharge end is in sections surrounded by chambers, means for introducing and removing fluid under pressure into and from said chambers, said fluid under pressure being introduced and removed sequentially in a manner that a peristaltic advance movement is brought about in the hose.

2. The apparatus as claimed in claim 1, characterized in that the casing is composed of stay tubes of rigid material disposed in sequence one after the other and detachably interconnected with one another, each of said tubes on its interior side containing a tubular piece of resilient material, which piece at its ends is in tightening connection with the ends of the stay tube and together with the same forms an inwardly expansible chamber which by means of connecting means on the stay tube is connectable to programmed source of pressure fluid.

3. The apparatus as claimed in claim 2, characterized in that the hose forms a separate coherent element inside of the tubular pieces arranged in a sequence.

4. The apparatus as claimed in claim 2, characterized in that the stay tubes at their ends are formed with annular connect ing flanges secured together by fasteners, said flanges at facing surfaces in each tubular connection being provided with annular grooves for receiving flange collars formed in a corresponding manner on each of the resilient tubular pieces enclosed by the allied stay tube.

5. The apparatus as claimed in claim 4, characterized in that the inlet section is adapted to be actuated by a mechanic closing means provided between batch supplying members and the other sections of the hose.

6. The apparatus as claimed in claim 5, characterized in that the wall thickness of the elastic tubular pieces increases from a middle portion towards the ends of each of said pieces.

7. The apparatus as claimed in claim 2, characterized in that at least part of the individual chambers are connected to outlots in which during the relief of a chamber from pressure a counterpressure is produced to be surmounted when introducing a batch of explosive into the hose section enclosed by said chamber.

tained, the magnitude of which is adjustable to the desired counterpressure.