US3581619A

US3581619A - Machine for continuously producing detonating caps, containing primary and secondary explosive charges

Info

Publication number: US3581619A
Application number: US747243A
Authority: US
Inventors: Nicolas Makay
Original assignee: FG Kretschmer and Co
Current assignee: FG Kretschmer and Co
Priority date: 1968-06-20
Filing date: 1968-07-24
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01
Also published as: AU3997368A; CH498366A; BR6908286D0; GB1209536A; AU441070B2; FR1580314A; AT293837B

Abstract

This invention is directed to a multistation, continuously operating, rotary machine for successively partly filling detonator cap casings first with a predetermined charge of secondary explosive and compressing same to a predetermined density and then completing the filling of the casings with a predetermined charge of primary explosive and compressing same to a predetermined density. The filled detonator caps are discharged through a cleaning unit and means are provided for detecting and ejecting faulty or imperfectly filled casings.

Description

United States Patent [56] References Cited UNITED STATES PATENTS lO/l943 Williams.i.....................

Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Jerald J. Devitt [72] Inventor Nicolas Makay Rio De Janeriro, Brazil 747,243

[2]] Appl. No [22] Filed July 24. I968 Patented June I, l97l I 1 [73] F. G. Kretschmer & C0.

Assignec Vaduz, Liechtenstein, Europe AttorneysErich M. Radde, Charles A. McClure, Gerard J.

Weiser and Alfred Stapler I541 MACHINE FOR CONTINUOUS PRODUCING ABSTRACT: This invention is directed to a multistation, cony partly DETONATING CAPS, CONTAINING PRIMARY tinuously operating, rotary machine for successivel filling detonator cap casings first with a predetermined charge of secondary explosive and compressing same to a predetermined density and then completing the filling of the casings with a predetermined charge of primary explosive and compressing same to a predetermined density. The filled detonator discharged through a cleaning unit and means are provided for detecting and ejecting faulty or imperfectly filled m a no 8 .m D. S a a C C 0 2 6 3 8 30 %bfl 4M% i s F u R m A m m H n u C m m E m V m m I S n 0 m m .LS P.m. u XF m m Eg u Y.m m m Rw m m Am m m D N h n 6 M9 r. C m um m M no G C d N5 S L M Al U .m F N U m s w w PATENTED JUN nan 35 1519 SHEET 1 OF 6 m/vE/vme A/MOLAS NA KAY PATENTED JUN 1 1974 saw 2 BF 6 F ATENTEn JUN 1197i 3.581.619

SHEET 3 BF 6 //v vs/wm A/ICOLA s NAKA y B7 MMKMQL MACHENEFOR CONTINUOUSLY PRODUCING DETONATING CAPS, CONTAINENG PRIMARY AND SEQONDARY EXPLOSIVE CHARGES BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates generally to new and useful improvements in filling equipment for granular free-flowing materials and particularly seeks to provide a novel multistation, continuously operating, rotary machine for filling detonator cap casings with predetermined charges of secondary and primary explosives, each of which becomes compressed to a predetermined density as an incident to the operation of the machine.

2. Description of the Prior Art Detonating or primer caps serve as detonating or primer charge for dynamite or ammonium nitrate explosives. Such caps are detonated by means of a burst of flame. They consist of metallic or plastic casings or housings into which a suitable explosive is filled.

Heretofore, detonating caps of simplest composition consisted of copper casings filled with mercury fulminate. However, such detonating caps are sensitive to inadvertent impact and to water and, therefore, are not produced or used anymore. At present detonating caps filled with a primary explosive and a secondary explosive are used. The primary explosive can be ignited by means of a burst of a flame. Its detonating power, however, is insufficient. Therefore, a secondary explosive, for instance, a charge of trinitro toluene must be employed in the caps in addition to the primary explosive. The caps are produced by first partly filling the casing with the secondary explosive and compressing the same, whereafter the primary explosive is introduced therein and compressed to complete the filling of the casing.

The detonating caps are produced at present in such a manner that the casings are either separately and manually filled and compressed, or to 150 casings are placed into a common container, which is called a press plate, and are simultaneously filled. Filling is effected by means of two plates which are slidably arranged with respect to each other and which possess boreholes corresponding to the casings positioned below said plates. To introduce a predetermined amount of explosive into the casings, the lower plate is placed under the upper plate so that the holes in the upper plate are closed at their bottom and are not in register with the holes in the lower plate and the openings of the casings. Thus they represent cups of a predetermined volume into which a predetermined amount of explosive is introduced. On shifting the lower plate so that the holes of the two plates are in register with each other and the casings, the explosive is permitted to drop into the casings. The press plate holding the explosive-filled casings is then placed into a press having as many compression plungers as there are casings and the explosive is compressed in the casings by means of said plungers. In this manner first the secondary explosive and then the primary explosive is introduced and compressed.

The filling machines and presses stand in separate rooms which are separated from each other by armored doors. They are also separated from the operating crew. Usually they are operated automatically.

To diminish the danger of explosion on producing detonating caps, the procedure in Europe, at present, is as follows: The primary explosive is filled into small caps and is compressed therein. These primary explosive caps are then inserted into the casings in which the secondary explosive has been filled and compressed. Thereby, any damage to the machines due to explosion is very considerably reduced. The procedure in USA differs therefrom insofar, as the primary explosive is added directly to the compressed secondary explosive in the casing and is then compressed therein. This requires special precautionary measures and devices which function to exactly control the charges and to maintain the compression force within predetermined limits. All the required devices and procedures are remotely controlled and photometrically adjusted. This is rather expensive and requires five to seven attendants and considerable space. Furthermore, the detonating caps must be carefully inspected, independently from their mode of manufacture, with respect to the required amount of primary and secondary explosive, i.e. whether sufficient amounts thereof are present in the caps. This can be done either by checking the weight of the resulting detonating caps or by determining the height of the compressed explosivc in the caps. The caps must also be cleaned after their manufacture and before packing in order to remove any particles of explosive adhering thereto.

It may be mentioned as further disadvantage of the heretofore employed single-unit or single-batch production methods that the labor costs are very high and the manufacturing process is subjected to human shortcomings and unreliability. But even disregarding these disadvantages, the danger of explosion is always imminent.

When filling a number of caps and compressing the explosives simultaneously, the above mentioned disadvantages are somewhat avoided but they still exist to some extent. However, the danger of explosion and, as a result thereof, the possibility that the machines will be destroyed, are considerably increased due to the larger amounts of explosives which are introduced and compressed at the same time. Remotely controlled, automatically operating filling and compressing machines require large investments and high maintenance and repair costs so that the damage caused by explosions and the resulting decrease in production are considerable. A further disadvantage of the heretofore employed procedures results from the fact that control of faultless production by determining the weight or height of the explosive can be carried out only after the caps have been filled. Thus faulty detonating caps cannot readily be eliminated. The weight of the explosive may be affected by differences in weight of the empty casings and the height of the explosive in the casing by differences in compression pressure.

SUMMARY OF THE INVENTION It is one object of the present invention to overcome all the disadvantages of the known manufacturing processes by providing a novel automatic filling and compressing machine for the continuous production of detonating caps which permits effective filling of the casings in a uniform manner and without undue danger.

Another object of the present invention is to provide a simple and effective process of automatically producing detonating caps by means of such a machine.

A further object of the present invention is to provide detonating caps containing secondary and primary explosives compressed therein which caps have been made by means of such a machine.

Other objects of the present invention and advantageous features thereof will become apparent as the description proceeds.

in principle the automatic filling and compressing machine used in the continuous manufacture of detonating or primer caps according to the present invention comprises a working table or platform rotating in stages around its center axis. The angle of rotation of this table is controlled by a shift dog and an indexing gear or wheel or a notched disc which are driven by a working gear. Said working table is provided with receiving containers or pockets into which the casings are inserted. Connected with said working table is a tool holder which is capable of moving upwardly and downwardly and the movement of which is regulated by an eccentric and a piston rod attached to the working gear which causes rotation of the working table. The upward and downward movement of the tool holder is synchronized with the step-by-step rotation of the working table. Furthennore, the machine is provided with metering devices for charging the casings with predetermined quantities of explosives. The tool holder holds plungers for compressing the explosives. Said plungers are provided with sets of weights allowing adjustment of the compression pressure to a predetermined value. The machine also comprises a means for ejecting faulty or improperly filled as well as properly filled detonating caps. Said ejector means are operated and regulated by a discharging or separating device for removing said detonating caps which device is operated and controlled by the compression plungers. Furthermore, a device for supplying the casings to the working table, which device is driven by means of a gear rim or toothed rim and the operation of which depends on the rotation of the working table, and a conveyor belt for conveying the filled detonating caps to a cleaning drum are also provided.

The machine according to the present invention has a number of advantages over heretofore known apparatus and devices. It permits uniform filling and compressing of the explosives substantially without danger. The amount of each charge of explosive can be determined accurately and independently from any subsequent charge. Faulty and improperly filled detonating caps can be detected, separated from properly filled caps, and ejected. Pressure of always the same magnitude is applied to each charge of explosive. Filling the detonating caps and compressing the charges especially of highly sensitive explosives as well as supplying the empty casings and cleaning the finished caps is carried out automatically, thus considerably reducing the danger to workers and machinery. The machine according to the present invention is of simple construction and requires only a relatively small space. Thus the low costs of the machine and its automatic operation result in a considerable reduction of the production costs of the detonating caps in comparison to the heretofore used apparatus and machines.

BRIEF DESCRIPTION OF THE DRAWINGS The attached drawings serve to illustrate the automatic filling and compressing machine according to the present invention whereby:

FIG. I is an elevation thereof;

FIG. 2 is a top plan view thereof;

FIG. 3 is a cross-sectional view of the specific device for positioning the casings, taken along line 3-3 of FIG.;

FIG. 4 is an elevation, partially in cross section, of the metering device, taken along line 4-4 of FIG.;

FIG. 5 is a cross-sectional view thereof, taken along line 55 of FIG.;

FIG. 6 is a crosssectional view of the compressing station, taken along line 6-6 of FIG.;

FIG. 7 is a cross-sectional view of the ejector and discharging device for the finished detonating caps, taken along line 7-7 of FIG.;

FIG. 8 is a cross-sectional view of the cleaning station, taken along line 88 of FIG; and

FIG. 9 is an elevation, partially in cross section, of the cleaning drum.

In these drawings identical reference numerals indicate like parts of the machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The machine shown in the drawings is an automatic filling and compressing device for continuously producing detonating caps. The machine is constructed as automatic rotary machine with eight working stages.

As shown in FIGS. 1 and 2, said automatic filling and compressing machine according to the present invention has a rotating working table l which is supported by a base plate 2 and is provided with vertically reciprocable tool holder 3. Working table I is rotated by driving mechanism 4 arranged underneath base plate 2. Since all the movements must take place synchronously, the step-by-step rotation of working table I and the reciprocating movement of tool holder 3 are coupled with each other. Eccentric 6, fit to main shaft 5, operates tool holder 3 by means of eccentric strap 7 but only when shift dog 8 driven by means of angular drive 9 by main shaft 5 disengages shifting wheel 10. Toothed wheel 11 provided on eccentric strap 7 of working table 1 controls operation of the feeder device 12. The casings 13 are supplied thereto through feeder tube 14 from vibrating storage container 15 from which the empty casings 13 are supplied to feeder 12 with their bottoms downwardly. Toothed wheel 11 also regulates movement of conveyor belt 51. Exact alignment of tool holder 3 and working table I is effected by conical peg 116 provided on working table 1 which engages corresponding centering bores 17 of tool holder 3.

The eight working stages of the machine as illustrated in the drawings are shown in FIG. 2 as follows:

A. Placing casing l3 into positioning container 18 of working table l.

B. Introducing the required quantity of the secondary explosive.

C. Compressing the secondary explosive charge.

D. Introducing the primary explosive.

E. Compressing the primary explosive charge.

F. Ejecting faulty caps.

G. Discharging the properly filled and compressed detonating caps 21.

H. Cleaning the positioning container 18.

The first working position A is illustrated in FIG. 3. In this position casing 13 is conducted by means of easing feeder device 12 to the positioning container 18 of rotating table 1 by the action of plunger 22. Positioning container 18 is provided with a conical two-part pocket or receiving clamp 23 into which the casing 13 is introduced. Said receiving clamp 23 is encased by heavy-walled cushioning sleeve 24 made of plastic. Should casing 13 detonate during the filling operation, the detonation force will be absorbed by said plastic sleeve 24. As a result thereof excessive damage to the machine will be prevented. If a casing 33 should have been inserted upside down into pocket 23 or if the casing should not correspond to the required measurements, it is pushed through the positioning container l8 by plunger 22.

Ring 19 serves to reset discharge device 29 which will be described more in detail hereinafter, after stage H has been completed. Overload release rod 20 stops operation of the machine by disengaging the drive if a casing 13 has become tilted in pocket 23.

In working positions 8 and D the required quantities of secondary explosive (position B) or primary explosive (position D) are measured by means of metering devices 25 and are introduced into casings l3. Said metering devices 25 are illustrated in FIGS. 4 and 5. Metering of the explosive is effected by oscillating metering valve 26. This valve 26 is operated by sensing rod 27 which rests on control bar 28 of the discharge device 29 and causes pinion 31 firmly attached to the oscillating metering valve 26 to operate by means of rack 30 attached to discharge device 29. As a result thereof the metering valve 26 which is provided with a peripheral metering pocket or recess corresponding to the required quantity of explosive, is caused to pass below supply hopper 33 for the explosive. On rotation of metering valve 26, the metered quantity of secondary or, respectively, primary explosive is emptied into charging funnel 34 arranged therebelow and is introduced from said funnel 34 into casings 13. In case of faulty metering or other malfunctioning of the machine the discharge device 29 will be actuated by the sensing rod 27 being unable to rest on control bar 28 but passing through borehole 35 provided therein. As a result thereof supply of the explosive to charging funnel 34 and casing 13 will be interrupted.

As illustrated in FIG. 6, compression of the secondary explosive as well as the primary explosive in positions C and E and checking whether the required amount of compressed explosive has been filled into the casings are controlled by cooperation with the discharge device 29 which is actuated by improper amounts of explosive and by unsatisfactory compression. Compression plunger 36 enters casing 13 to an extent predetermined by a preset weight and, thereby, compresses the explosive. This causes weight 37 to be lifted for a distance a, for instance, for about 1 mm. from its original position. If too small a quantity of explosive or none at all is present in the casing, weight 37 will not be lifted and the discharge device 29 will be released by penetration of locking bolt or detent 38 thereinto. This causes locking pin 40 to be pulled down by lever 39 so that control bar 28 is pushed forward by spring 41 (see also FIGS. 4 and Hold down means 42 is provided at the compression station. Said hold down means 42 prevent pulling out of casing 13 from positioning container 13 by plunger 36.

Ejection of faulty detonating caps as well as of properly filled caps 21 is effected in positions F and G by the device illustrated in FIG. 7. Sensing rod 43 is controlled by the discharge device 29 in the same manner as described hereinabove for metering the explosives. Thereby, when sensing rod 43 rests upon control bar 28, the faulty or, respectively, the properly filled detonating cap 2! is ejected by cooperation of rack 44, pinion 45 actuated by said rack 44, and another rack 46 cooperating with said pinion 45. Ejector plunger 47 attached to rack 46 causes ejection of the detonating cap by its downward movement. On the other hand, when sensing rod 43 is caused to enter borehold 35, ejector plunger 47 remains in its nonejecting position.

FIG. 8 illustrates the manner in which the positioning container 18 is cleaned in working position H. On the downward movement of tool holder 3, the air present in bellows 48 is compressed and, on escaping therefrom, is forced through container 18, thereby removing any adhering explosive particles and cleaning the container 18 before a new empty casing is inserted thereinto. On the upward movement of tool holder 3 air is aspirated into bellows 48 by valve 49.

The discharge device 29 operates in each of the eight working positions and, after one complete rotation of working table 1, is reset to its initial position by means of ring 19.

The faulty detonating caps ejected in position F are counted in a manner known per se and are deposited in a container (not shown). The properly filled detonating caps ejected in position G are also counted and are deposited in receptacle 50 of conveyor belt 51. Said conveyor belt 51 conducts caps 21 to a rotating cleaning drum 52 illustrated in FIG. 9. The axis of said drum 5-2 is somewhat inclined below the horizontal so that the sawdust 53 present therein and the detonating caps 21 travel in the direction of the drum opening 54. The sawdust is removed from the drum by falling through holes 55 in the wall of the drum before they have reached the drum opening 54. The separated sawdust is collected in special tank 56. Thus only the cleaned detonating caps 21 are collected in receptacle S7. Said container 57 is removed, for instance, every 30 to 60 minutes during a shutdown period of the machine. At the same time supply hoppers 33 in positions B and D are filled with secondary and primary explosive.

Of course, many changes and variations in the construction of the machine, the means for inserting the easing into the positioning container of the working table, the means for filling the casings with explosive and for compressing the explosive therein, the devices for controlling proper filling of the casings and proper compressing of the explosives in the easings, the ejector means for ejecting faulty as well as properly manufactured detonating caps, the means for causing proper cooperation of the various operating means at the various working stations, and the like may be made by those skilled in the art in accordance with the principles set forth herein and in the claims annexed hereto.

1 claim:

1. A machine for continuously producing detonating caps containing primary and secondary explosive charges, said machine comprising:

a. a working table rotatable in stages around its center axis,

b. a vertically reciprocable tool holder,

c. drive means for synchronously step-by-step rotating the working table and vertically reciprocating the tool holder,

d. the working table having positioning containers for the casings of the detonating caps,

e. the tool holder being provided with explosive metering devices,

f. with means for compressing the explosive charges metered into the casings, and

g. with ejector means for ejecting the detonating caps,

h. discharging means for discharging the detonating caps from the machine, said discharging means being actuated by the compressing means and controlling operation of the metering devices and the ejector means,

i. means for supplying empty casings to the positioning containers of the working table, and

j. means for conducting the finished detonating caps to a cleaning device.

2. The machine as defined in claim 1, wherein a shift dog and an indexing gear driven by a working gear are provided to cause step-by-step rotation of the working table at the desired angle of rotation and wherein an eccentric strap is provided cooperating with the tool holder, said eccentric strap actuating the tool holder by means of an eccentric of the drive means to cause synchronous reciprocating movement of the tool holder in accordance with the step-by-step rotating movement of the working table.

3. The machine as defined in claim 1, wherein a conical peg is provided at the working table, said conical peg engaging a corresponding centering bore provided in the tool holder, said conical peg and bore causing exact alignment of working table and tool holder.

4. The machine as defined in claim 1, wherein sets of weights acting on the compressing means are provided, said sets of weights being adjustable to the compression pressure required for the respective explosive.

5. The machine as defined in claim 1, wherein a locking bolt is provided at the compressing means, a control bar is provided at the discharge means, said control bar being actuated by said locking bolt, and sensing rods are provided at the metering means and the ejector means, said sensing rods, control bar, and locking bolt cooperating in actuating the discharging means to eject faulty detonating caps and in stopping operation of the metering devices and filling the casings with explosive.

6. The machine as defined in claim 5, wherein the sensing rods are resting on the control bar of the discharging means to actuate the metering devices and discharging means on downward movement of the tool holder.

7. The machine as defined in claim 5, wherein the sensing rods are passing through bores provided in the control bar of the released discharging means to stop operation of the machine.

8. The machine as defined in claim 1, wherein a discharging means is assigned to each positioning container.

9. The machine as defined in claim 1, wherein the number of positioning containers is determined by the number of explosives metered and compressed thercinto.

10. The machine as defined in claim 1, wherein the positioning container comprises a conical two-part receiving clamp and a thick-walled cushioning sleeve of plastic material, said sleeve capable of absorbing the detonating force of an accidentally detonatin g casing.

11. The machine as defined in claim 1, wherein the metering device comprises an oscillating metering valve having a peripheral metering recess of a size corresponding to that of the respective explosive to be filled into the casing, a sensing rod, a rack cooperating therewith, and a pinion cooperating with the metering valve, asupply hopper containing the explosive to be fed to the metering recess, and a charging funnel to feed the explosive to the casing, said sensing rod, rack, and pinion causing the metering valve to oscillate and to pass below said supply hopper so as to fill the recess with explosive, said metering valve, on its oscillating movement, being alternately filled with and emptied of explosive.

12. The machine as defined in claim 1, wherein the means for conducting the finished detonating caps to the cleaning device comprises a conveyor belt and wherein the cleaning ing the detonating cap, said bellows cleaning the positioning container by the air expelled therefrom on downward movement of the tool holder and aspirating air on upward movement of said tool holder.

15. The machine as defined in claim ll, wherein the means for supplying empty casings to the positioning containers of the working table are operated by means of a toothed wheel driven by the drive means synchronously with the step-by-step rotation of the working table.

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Claims

1. A machine for continuously producing detonating caps containing primary and secondary explosive charges, said machine comprising: a. a working table rotatable in stages around its center axis, b. a vertically reciprocable tool holder, c. drive means for synchronously step-by-step rotating the working table and vertically reciprocating the tool holder, d. the working table having positioning containers for the casings of the detonating caps, e. the tool holder being provided with explosive metering devices, f. with means for compressing the explosive charges metered into the casings, and g. with ejector means for ejecting the detonating caps, h. discharging means for discharging the detonating caps from the machine, said discharging means being actuated by the compressing means and controlling operation of the metering devices and the ejector means, i. means for supplying empty casings to the positioning containers of the working table, and j. means for conducting the finished detonating caps to a cleaning device.

9. The machine as defined in claim 1, wherein the number of positioning containers is determined by the number of explosives metered and compressEd thereinto.

10. The machine as defined in claim 1, wherein the positioning container comprises a conical two-part receiving clamp and a thick-walled cushioning sleeve of plastic material, said sleeve capable of absorbing the detonating force of an accidentally detonating casing.

11. The machine as defined in claim 1, wherein the metering device comprises an oscillating metering valve having a peripheral metering recess of a size corresponding to that of the respective explosive to be filled into the casing, a sensing rod, a rack cooperating therewith, and a pinion cooperating with the metering valve, a supply hopper containing the explosive to be fed to the metering recess, and a charging funnel to feed the explosive to the casing, said sensing rod, rack, and pinion causing the metering valve to oscillate and to pass below said supply hopper so as to fill the recess with explosive, said metering valve, on its oscillating movement, being alternately filled with and emptied of explosive.

12. The machine as defined in claim 1, wherein the means for conducting the finished detonating caps to the cleaning device comprises a conveyor belt and wherein the cleaning device is a downwardly inclined rotating drum filled with cleaning agent, said cleaning agent, on rotation of the drum causing separation of the detonating caps from adhering explosive, said cleaning drum being provided with means for separating the cleaning agent and the cleaned detonating caps and for discharging said cleaned detonating caps.

13. The machine as defined in claim 12, wherein the cleaning agent is saw dust.

14. The machine as defined in claim 1, wherein bellows are provided for cleaning the positioning container after discharging the detonating cap, said bellows cleaning the positioning container by the air expelled therefrom on downward movement of the tool holder and aspirating air on upward movement of said tool holder.

15. The machine as defined in claim 1, wherein the means for supplying empty casings to the positioning containers of the working table are operated by means of a toothed wheel driven by the drive means synchronously with the step-by-step rotation of the working table.