Ignition device for exothermic welding, mold for exothermic welding for the ignition device, and apparatus for exothermic welding comprising such a mold and such an ignition device

Abstract

The present invention relates to an ignition device for exothermic welding comprising an electrically conductive metal bushing (1) that can house a pellet of a first welding material (4) in electrical contact with the inner wall of an inner chamber (1c) of the bushing (1), provided with an electrically insulating cap (2) and a bottom base (1b) with an opening (1d) through which the first welding material (4) falls in an incandescent state onto a second welding material (4a) arranged in a weld mold (7) when an exothermic reaction has been triggered in the first welding material (4); an electrode (5) that goes through the cap (2) of the metal bushing (1) and comprises a top contact (5a) connectable to a power output (24) of a voltage generator and a bottom contact in the form of a filament (5b) that can be in electrical contact with the pellet of the first welding material (4), the filament (5b) being made of a material having a melting temperature greater than the ignition temperature of the welding material (4); as well as a contact-assuring element (3) which is guided into the inner chamber (1c) between the bottom base (1b) and the pellet of the first welding material (4).

Claims

1. Ignition device for exothermic welding comprising a metal container at least partially housable in a weld mold, the metal container comprising a top base closed by a cap, a bottom base and an inner chamber for housing a first welding material having an ignition temperature, and ignition means for triggering a first exothermic reaction in the first welding material intended for triggering a second exothermic reaction in a second welding material housed in the weld mold, wherein the metal container is an electrically conductive metal bushing housable in an electrically conductive top cap of the weld mold, which is designed for surrounding and contacting the metal bushing of the ignition device and which is connectable to a first pole of a power output of a voltage generator; the cap of the metal bushing is made of an electrically insulating material; the bottom base of the metal bushing has an opening through which the first welding material falls in an incandescent state towards the second welding material housed in the weld mold when the first exothermic reaction has been triggered; the inner chamber comprises an inner wall sized for housing the first welding material in the form of a solid pellet and suitable for placing the pellet of the first welding material in electrical contact with the inner wall of the inner chamber; the ignition means comprise an electrode that goes through the cap of the metal bushing and comprises a top contact connectable to a second pole of the power output of the voltage generator, and a bottom contact in the form of a filament that can be in electrical contact with the pellet of the first welding material; the filament is made of a material having a melting temperature greater than the ignition temperature of the first welding material; a contact-assuring element assuring electrical contact of the pellet of the first welding material with the filament is supported on the bottom base of the metal bushing, wherein the electrical contact-assuring element comprises a coil spring which is guided along an inner perimeter of the inner chamber and compressed by the pellet of the welding material when said pellet is housed in the inner chamber of the metal bushing before the exothermic reaction and released when the welding material gradually falls in an incandescent state towards the weld mold through the opening of the bottom base of the metal bushing.

2. Ignition device according to claim 1, wherein the second welding material is in the form of a solid pellet.

3. Ignition device according to claim 1, wherein the composition of the first and/or second welding material comprises between 40-60% of a reactive metal oxide obtained from a metal powder with a grain size distribution not greater than 1000 microns, apparent density comprised between 1.25 and 1.9 g/cm.sup.3 and a purity not less than 99.5%, suitable for compaction.

4. Ignition device according to claim 3, wherein the metal powder is copper or electrolytic copper.

5. Ignition device according to claim 3, wherein the reactive metal oxide additionally comprises an amount of the metal powder that does not exceed 20-25% of the total composition of the first and/or second welding material.

6. Ignition device according to claim 3, wherein the composition of the first and/or second welding material comprises materials suitable for provoking the reaction and alloy-forming elements which do not exceed 1 mm in diameter and a flux the particle size of which must be suited to that of the metal powder, the flux not exceeding 10% by weight of the final mixture.

7. Ignition device according to claim 1, wherein the metal bushing is cylindrical.

8. Ignition device according to claim 1, wherein the inner chamber is ring-shaped.

9. Ignition device according to claim 1, wherein the top base of the metal bushing comprises a perimetral support flange.

10. Ignition device according to claim 1, wherein the material of the filament is selected from group 6 transition metals, alloys thereof and alloys of at least one transition metal with at least another element that is not a transition metal.

11. Ignition device according to claim 1, wherein the material of the filament is a material having a melting temperature between 2,500° C. and 4,000° C.

12. Ignition device according to claim 1, wherein the filament is made of a material that reaches its melting temperature when a current between 4 and 10 amperes is applied thereto.

13. Apparatus for exothermic welding comprising an ignition device according to claim 1 and a mold, wherein the mold comprises: a top housing area for at least partially housing a metal container of an ignition device for exothermic welding containing a first welding material, a bottom housing for housing a second welding material and connected with the top housing area for receiving the first welding material in an incandescent state after the ignition device has triggered a first exothermic reaction such that the first incandescent welding material triggers a second exothermic reaction when it falls onto the second welding material; a bottom welding area designed for providing conductors to be welded by means of exothermic welding; a bottom vertical passage connecting the bottom housing with the welding area (26e) to allow the welding material melted by the second exothermic reaction to fall onto the conductors to be welded; wherein the top housing area being designed for at least partially housing the metal container of the ignition device.

14. Apparatus for exothermic welding according to claim 13, wherein it comprising an electrically conductive top cap which is designed for surrounding and contacting the metal bushing of the ignition device and which is connectable to the first pole of the power output of the voltage generator.

15. Apparatus for exothermic welding according to claim 14 furthermore comprising a remote electronic ignition device integrating the voltage generator with the power output connectable by said first pole to the metal bushing through the electrically conductive top cap of the weld mold by means of a first conductor cable and to the top contact of the electrode by means of a second conductor cable, the electronic ignition device being designed for being able to supply sufficient current intensity for a sufficient time to melt the filament of the ignition device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Aspects and embodiments of the invention are described below based on the schematic drawings, in which

(2) FIG. 1 is a partially sectioned top perspective view of an embodiment of an ignition device according to the present invention;

(3) FIG. 2 is an also partially sectioned side elevational view of the ignition device shown in FIG. 1;

(4) FIG. 3 is a partially sectioned bottom perspective view of the ignition device shown in FIGS. 1 and 2;

(5) FIG. 4 is a detailed view of an embodiment of the electrode comprised in the ignition device shown in FIGS. 1 to 4;

(6) FIG. 5 is a partially sectioned top perspective view of an embodiment of the weld mold according to the invention;

(7) FIG. 6 is a sectioned side elevational view of the weld mold shown in FIG. 5;

(8) FIG. 7 is a view of an embodiment of the apparatus according to the present invention incorporating the ignition device shown in FIGS. 1 to 4 and the weld mold shown in FIGS. 5 and 6;

(9) FIG. 8 is a wiring diagram of an embodiment of the remote electronic ignition device.

(10) Reference numbers identifying the following elements can be seen in these figures:

(11) 1 metal bushing

(12) 1a top base of the metal bushing

(13) 1b bottom base of the metal bushing

(14) 1c inner chamber

(15) 1d opening of the bushing

(16) 2 cap of the bushing

(17) 3 coil spring

(18) 4 first welding material (initiator)

(19) 4a second welding material

(20) 5 electrode

(21) 5a top contact

(22) 5b bottom contact in the form of a filament

(23) 5c connecting sector

(24) 5d blind hole

(25) 6 perimetral support flange

(26) 7 weld mold

(27) 7b bottom base

(28) 7c top housing area

(29) 7d bottom housing

(30) 7e welding area

(31) 7f bottom vertical passage

(32) 7g bottom ring-shaped support base

(33) 7h opening of the mold

(34) 7i insertion area

(35) 8 connector for the cap

(36) 8a clamp for the electrode

(37) 9a first conductor cable

(38) 9b second conductor cable

(39) 10 remote electronic ignition device

(40) 11 resistor

(41) 12 charging device

(42) 13 external power source

(43) 14 external power connector

(44) 15 wait indicator light

(45) 16 state of charge indicator light

(46) 17 charge indicator light

(47) 18 activation indicator light

(48) 19 warning alarm

(49) 20 on/off button

(50) 21a, 21b activating buttons

(51) 22 microcontroller

(52) 23 relay

(53) 24 power output

(54) 24a first pole of the power output

(55) 24b second pole of the power output

(56) 25 battery

(57) 25a positive contact

(58) 25b negative contact

(59) 26 conductors to be welded

(60) 27 top cap

(61) Embodiments Of The Invention

(62) In the embodiment shown in FIGS. 1 to 4, the ignition device comprises a cylindrical electrically conductive metal bushing —1— comprising a top base —1a— with a perimetral flange —6— closed by a cap —2— made of an electrically insulating material, a bottom base —1b— and an internal ring-shaped chamber —1c— in which the first welding material —4— in the form of a solid or compacted pellet is housed. The bottom base —1b— of the metal bushing —1— has a central circular opening —1d— through which the first welding material —4— can fall in an incandescent state towards the weld mold —7— when the first exothermic reaction has been triggered.

(63) The inner chamber —1c— comprises an inner wall sized for housing the first welding material —4— in the form of a solid pellet and with an inner perimeter complementary to the outer perimeter of the pellet of the welding material —4— for placing the pellet of the welding material —4— in electrical contact with the inner wall of the inner chamber —1c—.

(64) A coil spring —3— is supported on the bottom base —1b— of the metal bushing —1—, said coil spring being guided into the inner perimeter of the inner chamber —1c— and compressed by the pellet of the first welding material —4— housed in the inner chamber —1c— of the metal bushing —1— before the exothermic reaction. The coil spring —3— is released when the first welding material —4— gradually falls in an incandescent state vertically through the passage defined by the coils of the coil spring towards the second welding material —4a— (FIGS. 5, 6) through the opening —1d— of the bottom base —1b— of the metal bushing —1—, and when it is released it expands upwardly scraping the inner wall of the inner chamber —1c— of the metal bushing —1—.

(65) The ignition device further comprises ignition means comprising an electrode —5— that goes through the cap —2— of the metal bushing —1— and comprises a top contact —5a— and a bottom contact in the form of a filament —5b— which is in electrical contact with the pellet of the welding material —4—. The top contact —5a— and the filament —5b— are connected by a connecting sector —5c— from which the filament —5b— which is assembled in a blind hole —5d— of the connecting sector —5c— emerges.

(66) The filament —5b— is made of a material having a melting temperature greater than the ignition temperature of the welding material —4—, such as tungsten, for example, which has a melting temperature of 3422° C. and reaches that melting temperature when a current between 4 and 10 amperes is applied thereto for at least 2 to 5 seconds.

(67) The mold —7— for welds illustrated in FIGS. 5 and 6 comprises a parallelepiped body with a top cap —27— made of an electrically conductive material, as well as a bottom base —7b—. The top cap —27— comprises a central and cylindrical upper opening (not depicted) through which the metal bushing —1— of the ignition device described above in reference to FIGS. 1 to 4 is inserted, such that the metal bushing —1— is at least partially located in the housing area —7c— of the mold, with the perimetral flange —6— on the actual cap —27— of the mold. A pellet of the first welding material —4— is arranged inside the metal bushing —1—.

(68) A bottom housing —7d— for housing a pellet of a second welding material —4a— is located below the top housing area —7c— of the mold, said bottom housing —7d— communicated with the top housing —7c— for receiving the first welding material —4— in an incandescent state after the ignition device has triggered the first exothermic reaction, such that the first incandescent welding material —4— triggers a second exothermic reaction in the second welding material —4a—. The bottom housing —7d— is designed for housing the second welding material —4a— in the form of a solid pellet having dimensions that are greater than the pellet of the first welding material —4— and comprises a bottom ring-shaped base —7g— supporting the solid pellet of the second welding material —4a— and comprising an opening —7h— into which a bottom vertical passage —7f— opens towards the bottom housing —7d—. The bottom vertical passage —7f— communicates the bottom housing with a welding area —26e— to allow the welding material —4, 4a— melted by the second exothermic reaction to fall onto a bottom welding area —7e— on the area of attachment where the conductors to be welded —26— must be welded by means of exothermic welding. The conductors to be welded —26— are immobilized in a conventional manner in an insertion area —7i— located above the bottom base —7b— of the mold —7—.

(69) The electrically conductive top cap —27— surrounds and contacts the metal bushing —1— of the ignition device, and is provided with a connector —8— connected through a first conductor cable —9a— to a first pole —24a— of a power output —24— of a remote electronic ignition device —10— integrating a voltage generator (FIG. 7). In turn, the top contact —5a— of the electrode —5— is connected to a second pole —24b— of the power output —24— of the electronic ignition device —10— by means of a clamp —8a— and a second conductor cable —9b— (FIG. 7). The electronic voltage device —10— is capable of supplying enough power to melt the filament —5b—, such as a current of 4 to 10 A for at least 2 to 5 seconds for example.

(70) FIG. 8 shows an embodiment of the electronic ignition device —10— in which said device comprises a battery —25—, such as a 6V battery for example, a charging device —12— connectable to an external power source —13— through an external power connector —14—; a relay —23—, a resistor 11— and a microcontroller —22—, integrated in a casing. The battery —25— has a negative contact —25a— connectable to the first pole —24a— and a positive contact —25b— connected to the second pole —24b— of the power output —24—. The resistor —11— is interconnected between the positive contact —25b— and said second pole —24b—. whereas the relay —23— is interconnected between the positive contact —25b— of the battery —25—, the resistor —11— and the charging device —12—, for selectively connecting the positive contact —25b— of the battery —25— to the charging device —12— for charging the battery —25—, or to the second pole —24b— of the power output —24— for supplying power to the filament —5b—. In turn, the microcontroller —22— is connected to the positive contact —25b— of the battery —25—, to the charging device —12— and to the relay —23— for controlling the charge of the battery —25— and the power leaving through the power output —24—. The microcontroller —22— also comprises a timer for maintaining the power supply to the power output —24— for a sufficient supply time to successfully melt the filament —5b— and trigger the exothermic reaction in the welding material —4—.

(71) The electronic ignition device —10— further comprises an on/off button —20— connected to the positive contact —25b— of the battery —25— and to the microcontroller —22— for selectively switching the electronic ignition device on and off, as well as two activating buttons —21a, 21b— connected in parallel between the positive contact —25b— of the battery —25— and the microcontroller —22— for selectively activating the power supply to the power output —24— when they are pressed simultaneously. The electronic ignition device —10— additionally comprises

(72) a wait indicator light —15— connected to the microcontroller —22— that lights up when the electronic ignition device —10— is switched on;

(73) an activation indicator light —18— connected to the microcontroller —22— that lights up when the power supply to the power output —24— is activated;

(74) a charge indicator light —17— connected to the charging device —12— that lights up when the charging device —12— is charging the battery —25-; and

(75) a state of charge indicator light —16— connected to the microcontroller —22— that lights up when the microcontroller —22— detects that the charge of the battery —25— is below a predetermined charge threshold.

(76) These indicator lights are preferably light-emitting diodes (LEDs) emitting light of different colors.

(77) The electronic ignition device —10— also comprises an acoustic warning alarm —19— connected to the microcontroller —22— which is activated when the power supply to the power output —24— is initiated and remains activated at least until the exothermic reaction of the welding material —4— has ended and for a safe time period after the end of the exothermic reaction, corresponding to a cooling time that the mold requires until it has dropped to a safe temperature that does not involve the risk of injury for a person that gets close to the mold, for which purpose the microcontroller —22— can have a timer and/or a temperature sensor detecting a safe mold temperature after the end of the exothermic reaction that does not involve the risk of injury for a person that gets close to the mold.