US3656716A

US3656716A - Apparatus for kneading doughy explosives

Info

Publication number: US3656716A
Application number: US2004A
Authority: US
Inventors: Sten Herman Ljungerg; Lennart B T Sternhoff
Original assignee: Nitro Nobel AB
Current assignee: Nitro Nobel AB
Priority date: 1968-12-31
Filing date: 1970-01-12
Publication date: 1972-04-18
Anticipated expiration: 1989-04-18
Also published as: JPS4910723B1; ZM18569A1; CH511197A; FR2027472A1; DE1964583A1; GB1293920A; SE329117B; NO121708B; BR6915682D0; CA922305A; ES375047A1

Abstract

This apparatus comprises a flexible hose adapted to receive solid and liquid constituents of the explosive. This hose is surrounded by a flexible tube which in turn is surrounded by a rigid tube that is made of a series of sections secured together. Compressed air is supplied into the spaces between the flexible tube and successive sections of the rigid tube successively to force the mixture of the solid and liquid constituents of the explosive down through the hose peristalically. The solid ingredient is supplied to the hose from a hopper through a measuring chamber and rigid tube; and the liquid ingredient is supplied from a separate measuring chamber which comprises a flexible cylinder inside a rigid housing. Opposite ends of the cylinder are closed alternately; and alternately the outside of the cylinder is put under suction and under pressure. On suction, the liquid component is sucked into the cylinder from a supply source. On pressure the liquid component is forced out of the cylinder into the hose through a nozzle which surrounds the tube that delivers the solid component into the hose. This nozzle directs the liquid against the inside wall of the hose to prevent the solid ingredient from sticking to the hose.

Description

United States Patent Ljungerg et al.

[151 3,656,716 [451 Apr. 18, 1972 [54] APPARATUS FOR KNEADING DOUGHY EXPLOSIVES [72] Inventors: Sten Herman Ljungerg; Lennart B. T.

Sternhofi, both of Stockholm, Sweden [73] Assignee: Nitro Nobel AB, Gyttorp, Sweden [22] Filed: Jan. 12, 1970 [21] Appl. No.: 2,004

[30] Foreign Application Priority Data Dec. 31, 1968 Sweden ..18079/68 [52] U.S. Cl ..259/4 Primary Examiner-Robert W. Jenkins Attorney-Shlesinger, Fitzsimmons & Shlesinger [57] I ABSTRACT This apparatus comprises a flexible hose adapted to receive solid and liquid constituents of the explosive. This hose is surrounded by a flexible tube which in turn is surrounded by a rigid tube that is made of a series of sections secured together. Compressed air is supplied into the spaces between the flexible tube and successive sections of the rigid tube successively to force the mixture of the solid and liquid constituents of the explosive down through the hose peristalically. The solid 'ingredient is supplied to the hose from a hopper through a measuring chamber and rigid tube; and the liquid ingredient is supplied from a separate measuring chamber which comprises a flexible cylinder inside a rigid housing. Opposite ends of the cylinder are closed alternately; and alternately the outside of the cylinder is put under suction and under pressure. On suction, the liquid component is sucked into the cylinder from a supply source. On pressure the liquid component is forced out of the cylinder into the hose through a nozzle which surrounds the tube thatdelivers the solid component into the hose. This nozzle directs the liquid against the inside wall of the hose to prevent the solid ingredient from sticking to the hose.

4 Claims, 3 Drawing Figures SHEET 1 or 3 PATENTEDAPR 18 m2 lnvcnfor Harm"; L 'unblrK and. 3r l tnmu'f LAJSQMM a I 1 2 Adar-a PATENTEDAPR 18 m2 SHEET 2 [IF 3 r ,m lw in M bw m wk A JMJ Hm nr kw APPARATUS FOR KNEADING DOUGHY EXPLOSIVES This invention relates to an apparatus for kneading doughy explosives.

More particularly, this invention relates to an apparatus for kneading doughy explosives and including a longish hose of resilient 'naterial. According to concept emanating from applicants, the hose in this connection can from an inlet end to a discharge end be in sections surrounded by chambers, which are in connection with a controlled source of pressure fluid and which in a predetermined sequence are actuated by the pressure fluid to bring about a peristaltic advance movement of the explosive.

When feeding an explosive down into an apparatus of said kind, difficulties often arise due to the fact that dry or semidry substance in the explosive adheres to the walls of the hose adjacent the inlet opening, which can contribute to the finally kneaded explosive not having uniform properties or within some portions becoming faulty, such as differently moistened.

One main object of the invention is to provide for such an improvement of the known apparatus that said drawbacks are eliminated and a throughout uniform quality of the final explosive is attained.

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. 1 is a longitudinal sectional view of the inlet portion of the kneading apparatus according to a preferred embodiment of the invention,

FIG. 2 is a perspective and partially sectional view of a device for supply of liquid under pressure and FIG. 3 is a diagrammatic and partly sectional view of the apparatus below the inlet end.

Referring to the drawings, reference numeral 1 denotes a hose of some resilient material, such as natural rubber, for example, which uninterruptedly extends within and through a series of stay-tubes 2 arranged in sequence and the one connected with the other and preferably made of plastic or light metal. Each stay-tube 2 is at its ends provided with an outwardly projecting annular flange 3, through which fastening bolts extend, circumferentially distributed in a suitable manner.

Between each stay-tube 2 and the hose 1, the tube receives a tubular piece 4 consisting of some resilient material, such as synthetic rubber, for example, the wall thickness of which preferably increases from a middle portion towards each end and which at each end is formed with an annular flange 5. The annular flanges 5 are received in an annular groove formed in each of the averted faces of the end flanges of each stay-tube 2 and are retained there in a sealing manner. Formed in an annular flange 3 of each stay-tube 2 is a channel 6 opening into the interspace between the tube 2 and the associated resilient tubular piece 4 and connected to a tube 7. Positioned within the conduits or tubes 7 are valves 8 of two-way type which also are connected to branch conduits 9 from a common supply duct 10 from a pressure fluid source not shown which may contain compressed air. By controlled readjustment of the valves 8, the chambers 11 to 20 between the stay-tubes 2 and the tubular pieces 4 are connected in such a manner that a peristaltic advance feed movement is brought about in the hose. For this purpose, the chambers 14 to 20 are alternately connected with, respectively, the pressure duct 10 and a counterpressure container 21. Thus, when the explosive batch 22, for example, in the chamber 15 is to be fed down into the portion of the hose 1 surrounded by the chamber 16, the chamber 15 is connected to the duct 10 while the valve 8 of the chamber 16 is adjusted so that this chamber is connected to the counterpressure container 21. This results in that a predetermined pressure must be exerted on the resilient wall of the chamber 16 in order to allow the batch of explosive to be forced down under expansion of said wall. Hereby the kneading of the batch during its downward displacement from the inlet end to the discharge end of the hose becomes highly effective.

. Though all chambers may be connectable to the counterpressure container, the tubes 7 for the chambers ll, 12 and 13 located nearest to the inlet side of the apparatus, open into the atmosphere. The valves 8 positioned in said tubes 7 thus connect the chambers either with the pressure conduit 10 or with the atmosphere.

Reference numeral 23 denotes a programming unit which by means of signal wires 24 is connected to electromagnetic members 25 for controlled'actuation of the individual valves 8 in a sequence, which is required for bringing about the peristaltic advance movement. The counterpressure container 21 may be replaced by throttling members located in the tubes 7 or other suitable means.

The uppermost stay-tube 2 (FIG. 1) is provided with a cover 26 through which a feed tube 27 coaxial with the stay-tube 2 and the hose 1 passes and intended for supply of the dry or, if desired, moist phase of the constituents of the explosive. The central tube 27 is provided with hinged dampers or

valves

28 and 29 and with an upper hopper member 30 for supply of the dry substance. The two hinged

flaps

28, 29 are shown in position for downward feed of dry substance. When the tube 27 has been filled from above down to the closed flap 28, the flap 29 is closed for determining an exact quantity of dry substance, and thereafter the measured portion can be fed down into the kneading apparatus by opening the flap 28 while the flap 29 is still maintained in its closing position. The cover 26 encloses an internal annular space 31, which is in connection with a tube socket 32 on which the end of a hose 33 is secured in a sealing manner (FIG. 2). The bottom face of the cover 26 is provided with an annular nozzle 34. Said annular nozzle 34 is formed between an inner sleeve 35 constituting a guide for the tube 27 and an outer sleeve 36 rigidly secured to the bottom face of the cover. In the embodiment shown, the lower end of the inner sleeve 35 projects past the outer sleeve 36 and has a conical surface facing the hose 1 whereby liquid supplied under pressure to the tube 32 and consisting of e.g. glycerol trinitrate will be directed towards the interior wall of the hose 1 and thus prevent dry particles supplied at the same time through the tube 27 from adhering to said wall partly due to the rinsing effect caused thereby and partly by the wall during each advance of a batch being kept in a slippery condition by the liquid film which completely covers at least the upper portion of the interior wall of the hose 1. Tests carried out in practice have shown that the liquid which through the annular nozzle is fed to the dry or moistened explosive substance supplied through the tube 27 to bring about the desired consistency and the desired properties of the final explosive are intermixed with the dry substance in a considerably more effective manner than when the liquid phase also is supplied through a feed tube of the same type as the tube 27.

After that a charge of explosive consisting of the quantity of dry substance determined between the

hinged flaps

28 and 29 and a quantity of liquid determined by a liquid.dosing device to be described more below and discharged through the nozzle 34 has been supplied to the hose 1 and introduced into the chamber 11, the bottom portion of which has been closed by admittance of pressure fluid through the uppermost valve 8 shown in FIG. 3, the chamber 11 is closed at its top (see FIG. 1) by means of pistons 37 by pressure fluid supplied to cylinders 40 through channels 39 to act on the outwards facing end surfaces of the pistons 37. The pressure fluid is supplied in response to signals from the programming unit 23 through valves and ducts not shown here. The valves are of the same two-way type as the valve 8.

In order to achieve correct supply of liquid to the nozzle 34 an exact dosed quantity of liquid must be supplied under substantially constant pressure and at all events without pulsating changes of pressure. For this reason, the nozzle is fed with liquid from a dosing device of the type shown in FIG. 2. This dosing device has a measuring chamber 41 consisting of a cylinder of flexible material, such as para-rubber, the ends of which cylinder are bent over an outer cylinder 42 made of e.g. metal or rigid plastic. The end portions bent outwards are kept clamped in a liquid-proof manner between the cylinder 42 and an upper cover 43 and a lower cover 44. The covers 43, 44 are retained pressed against the cylinder 42 by means not shown here. The upper cover 43 is provided with a discharge tube 45 to which is attached the hose 33 leading to the inlet tube 32 of the apparatus. The discharge opening of the upper cover 43 houses a feed check valve 46 devised to open when the liquid in the dosing chamber is subjected to pressure. The lower cover 44 has an inlet opening with a feed check valve 47 devised to be closed when the liquid within the dosing chamber 41 is under pressure. Connected to the inlet opening and the check valve 47 is a supply tube 48 with the hose 49, which is in connection with a liquid container not shown.

. Opening into the tubular outer cylinder 42 is one end of a conduit 50, the outer end of which is connected to a cylinder 51 housing a piston 52 arranged in a sliding and sealing manner within the cylinder 51. The piston 52 has a piston rod 53 connected to a control or pilot piston 54. Said piston 54 is in a sliding and sealing manner arranged within a control cylinder 55 communicating with the cylinder 51. The pressure space within the cylinder 55 is connected to a pressure duct 56 which via a valve not shown is in connection with a pressure fluid source, for example, the pressure fluid conduit 10. The valve not shown is operated in response to signals from the programming unit 23.

The piston 52 is caused to perform its working stroke by pressure fluid being supplied through a pressure duct 57 which via a valve not shown here and of the same two-way type as the valves 8 and controlled from the programming unit 23 is connected to a pressure fluid source, eg the conduit 10.

FIG. 2 shows the dosing device in a position in which pressure fluid is supplied through the conduit 57 so that the workingpiston 52 is caused to move to the right in the Figure and to force oil or other suitable pressure liquid out of the space between the piston 52 and the piston 53 through the conduit 50 into the space between the tubular cylinder 42 and the flexible cylinder 41 which thus is compressed and forces liquid within the cylinder 41 to be discharged through the hose 33 to the nozzle 34. During the working stroke of the piston 52, the valve in the conduit 56 is kept open towards the surrounding atmosphere. Upon completion of the working stroke, which is limited by means of a setting screw 58 in the bottom 59 of the cylinder 55, the valve of the conduit 57 is reversed and the conduit 57 is brought to communication with the atmosphere. At the same time, the valve of the conduit 56 is reversed so as to cause pressure fluid to be supplied to the conduit 56 and the cylinder 55 whereby the control piston 54 is displaced to the left in FIG. 3 and moves the piston 52 to the left-hand final position thereof. Since the piston 52 displaces more than the piston 54, the air present between the cylinder tube 42 and the flexible cylinder 41 will be sucked out during the movement to the left of the two pistons, so that the wall of the flexible cylinder 41 will be brought to bear against the wall of the cylinder tube 42. Hereby, liquid will be sucked out through the tube 49 into the flexible cylinder 41 which thus is filled with an exactly determined quantity of liquid of which a predetermined portion is pressed out by the next following working stroke within the cylinder 52. Preferably, the discharge opening of the liquid container not shown is positioned at a higher level than the inlet 48 whereby the liquid is caused during the return movement of the pistons 52, 54 to flow by its gravity and this is not sucked into the flexible cylinder 41. The explosive to be worked in the apparatus according to the invention may, for example, contain a known mixture of glycerol trinitrate and glycol dinitrate which together form the liquid constituent, and inorganic nitrate such as ammonium nitrate and a gelination promoting agent such as nitro cellulose forming the solid or granular constituent. The liquid constituent may amount to about 35 to 40 percent by weight of the mixture.

While one more or less specific embodiment of the invention has been shown and described, it is to be understood that this is for purpose of illustration only, and that the invention is not limited thereby, but its scope IS to be determined by the appended claims.

What is claimed is:

1. An apparatus for kneading doughy explosives composed of constituents in solid and in liquid state, said apparatus including a longish hose of resilient material disposed from an inlet end to a discharge end to be actuated by means adapted simultaneously with the kneading effect to bring about a peristaltic advance movement of the explosive, characterized in that connected to the inlet end of said hose is an annular nozzle which is in connection with a pressure fluid source and disposed to direct the liquid constituent against the inner wall of the hose around the solid constituent supplied through a central feed tube.

2. The apparatus as claimed in claim 1, characterized in that the liquid pressure source is adapted to deliver liquid under substantially constant pressure simultaneously with the'feeding down of batch of the solid constituent through the feed tube and in a quantity corresponding to the desired final liquid quantity in the doughy explosive.

3. The apparatus as claimed in claim 2, characterized in that the pressure liquid source consists of a closed cylinder having a flexible cylinder wall and a valve-controlled inlet opening and a valve-controlled discharge opening for liquid, said cylinder being positioned inside a closed pressure chamber devised to be supplied with a pressure fluid for delivery of a quantity of liquid determined by the supplied pressure fluid through the discharge opening of the cylinder to the annular nozzle.

4. The apparatus as claimed in claim 3, characterized in that the pressure fluid is supplied to the pressure chamber from a cylinder with a piston, the length of the stroke of which is predetenninable.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3;556;7l6' Dated April 18, 1972 Inventor( )5ten Herman LgLunszerp; and Bror Lennart Teodor Sternhoff It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The name of the first of the two Joint inventors has been changed to Ljungberg Sign d and sealed this 5th day of September 1972.

(SEAL) Attest:

EDWARD I I.I*LETCHER,JR. ROBERT GOTTSCHALK Atte sting Officer Commissioner of Patents USCOMM'DC 80376-P6Q I U SI GOVERNMENT PRINTING OFFICE: I969 O-366-334 FORM FO-IOSO (10-69)

Claims

2. The apparatus as claimed in claim 1, characterized in that the liquid pressure source is adapted to deliver liquid under substantially constant pressure simultaneously with the feeding down of batch of the solid constituent through the feed tube and in a quantity corresponding to the desired final liquid quantity in the doughy explosive.

4. The apparatus as claimed in claim 3, characterized in that the pressure fluid is supplied to the pressure chamber from a cylinder with a piston, the length of the stroke of which is predeterminable.