FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. PROCESS FOR PRESSING DELAY ELEMENTS FOR NON-ELECTRIC
INITIATORS
2.
1. (A) PARI SA
(B) Switzerland
(C) Bahnhofstrasse 7, 6301 Zug, Switzerland
The following specification particularly describes the invention and the manner in which it is to be performed.
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[01] The present patent refers to improvements
introduced into the process for pressing delay elements used in non-electric
initiators for explosives in general and explosive accessories in particular,
produced to provide the accurate firing time (delay time) for continuation of the
explosion sequence as programmed by detonation engineering, an optimized
process which obtains bulk density regularity and homogeneity of the pressed
material, providing the advantages of decreasing firing time variability, greater
repeatability and precision of the delay mixture dosage, and less height variation.
[02] As the technical means connected to
manufacturing delays nonelectric primers are well known, currently, one of the
best delay pressing processes for non-electric initiators takes place in the
following sequence:
[03] a) Firstly, the operator fills a spare mold with 50
zamak injected empty tubes of suitable length for the delay time to be
manufactured;
[04] b) Then, operator fills the delay mixture
container, according to the time to be manufactured. Operator also fills the lead
azide dosing funnel and the PETN dosing funnel, which remain within a room
behind the concrete wall of the press room;
[05] c) The operator programs in the control panel the
number of delay mixture doses corresponding to the delay time to be produced;
[06] d) Filling of dosing compartment is made through
automatic conveyance from the compartment to the power loading room, which is
isolated from the press and the operator by the concrete wall and the steel safety
door. In order to perform the automatic refill of the delay mixture, the safety door
automatically opens, the compartment on position with the dosing nozzle closed is
conveyed by a pneumatic cylinder to the refilling room, the door closes, and the 10
funnels of the compartment are automatically filled with the delay mixture.
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[07] e) When a set of doses is completed, the
compartment moves until aligning with the bottom of the delay mixture hopper. In
an automatic way, a pneumatic device shakes the compartment for some seconds,
for the granules to fill the dosing funnels. The compartment begin to move towards
the position of return to pressing section, in order to, when it passes close through
the Celeron plate (a low friction engineering material), the compartment dosing
funnels becomes filled with the proper volume of granules and delay mixture.
[08] f) The correct volume is transferred to the zamak
tube positioned and aligned on the bottom of the compartment; and
[09] g) The dosed tubes are transferred to the powder
pressing sector, where a punch compacts the powder into the tube with a single
operation, therefore obtaining the delay elements.
[010] The lead azide dosage process is carried out as
follows:
[011] A) The rotary cylinder containing 10 holes in row
corresponding to a line of the pallet containing the delay elements is in a position
that the holes are contacting the holes of the hopper (funnel) in conductive rubber;
[012] B) A pneumatic vibrator vibrates during two
seconds the cylinder so all the dosing holes are filled with granulated lead azide.
The cylinder then turns 180 degrees, in the indicated direction, pouring the volume
corresponding to 60 - 80 mg of lead azide over the alignment funnel, and from it to
the interior of delay element, on the delay mixture;
[013] C) The rotary cylinder returns to its original
position, and the pallet then advances to the next row. Such process is repeated
until 5 rows of 10 elements are with elements filled with 60 to 80 mg of azide;
[014] D) Afterwards the pallet goes through an
conveyor belt to the PETN dosing and pressing bay, which is in the same room,
however separated from the azide hopper and protected by a half concrete wall;
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[015] E) A PETN hopper with the same azide dosing
system then dispenses over the loose lead azide powder approximately 50 mg of
PETN;
[016] F) an horizontal pneumatic cylinder positions the
pallet with the first row of 10 elements aligned with a set of 10 vertical punches
similar to the final compaction set of the delay mixture;
[017] G) The punches then descend over the PETN
load, driven by the vertical pneumatic cylinders, compacting the PETN load. Note
that, in this process, the lead azide load is not directly compacted, but remains
encapsulated between the delay mixture load and the PETN load. This process
ensures higher efficiency for PETN starting from azide, resulting in azide loads
much lower than the conventional in delay fuzes, in addition to represent increased
safety in the process.
[018] H) After the complete production cycle of all 50
elements, the pallet (mold), is positioned at front of the punches to be withdrawn
by the operator; and
[019] I) The pallets are conducted to the delay fuze
press.
[020] This current process presents disadvantages,
inconveniences and limitations of the delay element, which presents variation in
apparent density of the powder, height variation, and firing time variation.
[021] “PROCESS FOR PRESSING DELAY
ELEMENTS FOR NON-ELECTRIC INITIATORS”, object of the present patent,
was developed to overcome the disadvantages, inconveniences, limitations and
technical issues of the referred up-to-date process by means of improvements that
achieve bulk density homogeneity and regularity of the compressed material,
bringing advantages of reducing the variability of firing time, greater repeatability
and accuracy for dosing delay mixtures and lower height variation.
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[022] The process of the present patent provides the
following novelties:
[023] I. Preliminary powder compaction with special
inner punch in dosing funnel is performed, achieving greater precision of power
dosage measure in dosing plate, with excellent homogeneity and regularity of
compressed material density;
[024] II. Final compaction of powder in delay element
is made into pads that are compacted one above the other, maintaining the bulk
density homogeneity and regularity of the material;
[025] III. Vibration in powder dosing is not necessary.
[026] The process of the present patent solved the
following problems that the current process not addresses:
[027] 1. The bulk density varies throughout the column
height, addressed by means of preliminary compaction and final compaction of
powder;
[028] 2. The press requires greater pressing effort,
addressed by means of preliminary compaction; and
[029] 3. Variation of firing time, addressed by means of
preliminary compaction and final compaction of powder.
[030] For a better understanding of the present patent,
the following figures are found attached hereto:
[031] Figure 1., which shows the schematic drawing of
the mixture metering device in its stage 1:
[032] Figure 2., which shows the schematic drawing of
the mixture metering device in its stage 2:
[033] Figure 3., which shows the schematic drawing of
the mixture metering device in its stage 3: and
[034] Figure 4., which shows the schematic drawing of
the mixture metering device in its stage 4.
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[035] According to the referred figures, the delay
element pressing process of the present patent is executed in the following
sequence:
[036] With the dosing funnels with powder delay
mixture, with lead azide and with PETN previously filled, the spare molds (M)
with injected empty zamak tubes (T) are filled, the number of successive dosages
of delay mixtures corresponding to the firing time to be produced is programmed
in the control panel, complemented with the following operations:
[037] Stage 1: The holes of dosing plate (1-B) are
aligned with the bottom of the dosing funnel (1-A) filling the holes with the
necessary quantity of powder delay mixture (3);
[038] Stage 2: The preliminary compaction punch (1-C)
descends compacting the powder (3) in the holes, thus obtaining the compacted
powder cylindrical pellet;
[039] Stage 3: The dosing plate (1-B) moves close to
bottom of the dosing funnel (1-A) and the table (2-A), leaving a compactedpowder
cylindrical pellet (3-A) of constant volume aligned with the pressing mold
(2-C) and the final compaction punch (2-B);
[040] Stage 4: The final compaction punch (2-B)
compresses the compacted-powder cylindrical pellet (3-A) obtaining compressed
powder (3-B) of delay mixture inside the zamak tube; and
[041] Stage 5: The logical controller of the press then
performs successive dosages and transfers/compactions of the delay mixture pellet,
as much as programmed for each tube, in multiple pressings, until completing the
total number of elements.
[042] The process for dosing the lead azide and PETN
powder delay elements into funnels takes place under conventional method.
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WE CLAIM:
1. “PROCESS FOR PRESSING DELAY
ELEMENTS FOR NON-ELECTRIC INITIATORS”,accomplished by the
sequence: with the dosing funnels having powder delay mixture, of lead azide and
PETN previously filled, the spare molds (M) with injected empty zamak tubes (T)
are filled, the number of successive dosages of delay mixtures corresponding to
the firing time to be produced is programmed in the control panel, complemented
with the operations, characterized by:
Stage 1: The holes of dosing plate (1-B) are aligned with the bottom of the dosing
funnel (1-A) filling the holes with the necessary quantity of powder delay mixture
(3);
Stage 2: The preliminary compaction punch (1-C) descends andcompact the
powder (3) in the holes, thus obtaining the compacted powder cylindrical pellet (3-
A);
Stage 3: The dosing plate (1-B) moves close to bottom of the dosing funnel (1-A)
and the table (2-A), leaving a compacted-powder cylindrical pellet (3-A) of
constant volume aligned with the pressing mold (2-C) and the final compaction
punch (2-B);
Stage 4: The final compaction punch (2-B) compresses the compacted-powder
cylindrical pellet (3-A) obtaining compressed powder (3-B) of delay mixture
inside the zamak tube; and
Stage 5: The logical controller of the press then performs successive dosages and
transfers/compactions of the delay mixture pellet, as much as programmed for
each tube, in multiple pressings, until completing the total number of elements.
2. “PROCESS FOR PRESSING DELAY
ELEMENTS FOR NON-ELECTRIC INITIATORS”, according to claim 1,
characterized by, preliminary powder compaction with preliminary compaction
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punch (1-C) inside the dosing funnel, providing greater precision of powder dose
measure and homogeneity, uniformity of the compressed material density and less
vibration of final column head height; final compaction of powder into delay
element, obtaining compressed powder (3-C) maintaining homogeneity and
uniformity of compressed material density; not requiring vibration in powder
dosage.