Technical field

The present invention relates to an oxygen lance igniter for igniting a thermal oxygen lance, intended to be slipped over the mouth of the oxygen lance up to a certain position and to ignite the oxygen lance under a supply of oxygen via the mouth of the oxygen lance, which igniter is provided with a securing mechanism for securing the oxygen lance during an initial ignition process . Background

An oxygen igniter of the type which is defined above is previously known by virtue of DE 2614155 Al . Oxygen igniters of the above-stated type are used primarily for thermal cutting and drilling and are usually found, inter alia, within the steel industry and in scrapping. Since the oxygen lance operates with just oxygen, some type of separate ignition function is required.

One problem with oxygen lances is to achieve safe lighting. For ignition, it is required that the oxygen lance tip has to be heated up to the ignition temperature of the iron, i.e. to about 1050°C. Known methods have long been to heat up the oxygen lance tip with the aid of a gas burner or with a coal fire. These methods are risky, since whoever starts up the lance is forced to be quite close to the lance mouth and if he happens to come too close, he can be hit by spraying molten iron.

Special igniters have therefore been developed for the lighting of oxygen lances. These usually consist of a sleeve which is open at its one end and which is slipped over the mouth of the lance. The sleeve can contain a combustion charge and an ignition charge, which latter can be connected to an external ignition member. The igniter can be started by placing a match, cigarette lighter or the like adjacent to the ignition member, or alternatively by scratching the ignition member against a friction surface. The ignition member ignites the ignition charge, which then ignites the combustion charge.

Examples of oxygen lance igniters similar to the type described in the previous paragraph are previously known by virtue of, for example, SE B 7605274-5, public Swedish application 8704421-0 and SE C2 521 801.

Use of the last-named igniter for igniting an oxygen lance also entails safety risks, with the risk of exposure of the handler to splashes of molten iron, and there is therefore a desire to further increase the safety consideration.

The object of the present invention is to provide an oxygen lance igniter having a more automated ignition process so as thereby to increase safety during use.

Summary of the invention

The object of the invention is achieved by an oxygen lance igniter characterized in that the securing mechanism is constituted by a tension spring whose one end is detachably fastened in the oxygen lance igniter and whose other end, via a locking device, is arranged to be coupled to the oxygen lance. The locking arrangement serves to ensure that the igniter is kept locked in place during the first phase of the ignition when oxygen begins to be supplied, whilst at the same time, when the lance is ignited, the securing mechanism slackens and the igniter, without the involvement of the handler, is released from the oxygen lance. Since the igniter is released without the involvement of the handler, the igniter is suitable for automated use. In particular, the ignition of an oxygen lance and the subsequent work functions of the oxygen lance can here be handled by a suitably programmed robot. In this way, rapid interventions for preventing stoppages in casting processes, for example, can be made by means of a robot-ignited and robot-controlled oxygen lance, without any person needing to be present in the process area and thereby risking exposure to molten metal.

According to a preferred embodiment of the oxygen lance igniter, the securing mechanism is of force-dependent configuration so as to allow the igniter to be separated from the oxygen lance under load.

According to another preferred embodiment of an oxygen lance igniter, the securing mechanism is of force- dependent configuration so as to be released under load.

According to yet another proposed embodiment of the oxygen lance igniter, the securing mechanism is arranged to be engaged with the oxygen lance and the, relative to the oxygen lance, far end of the oxygen lance igniter. Such an embodiment allows an easily securable fitting of the igniter over the tip of the oxygen lance.

Expediently, the locking device is constituted by a locking ring configured to be slipped over the shell surface of the oxygen lance. As the tension spring, a helical spring can be used. Preferred embodiments of the securing mechanism, locking device and tension spring contribute individually to constructions which have been shown to secure the oxygen lance in the igniter during an initial phase, but which release the igniter from the oxygen lance in a subsequent phase.

In order to control the separation between the oxygen lance and the igniter in a more clearly defined manner, according to yet another proposed embodiment, load- indicating means are provided to indicate suitable biasing of the securing mechanism. Brief description of drawings

The invention will be further described below by means of an illustrative embodiment with reference to appended drawings, in which:

Figure 1 shows schematically in longitudinal section an example of a known oxygen lance igniter fitted over the tip of an oxygen lance. Figure 2 shows schematically an oxygen lance igniter according to the invention fitted over the tip of an oxygen lance .

Detailed description of embodiments

The known igniter 1 shown in Figure 1 comprises a sleeve 2 having a combustion charge 3 and an ignition charge 4. The ignition charge 4 is connected to an external ignition member 5 via an ignition duct 6. The interior of the sleeve further comprises a space 7 intended to accommodate the tip 8 of an oxygen lance 9 having ducts 10 for an oxygen supply. The igniter 1 is started by placing a match, cigarette lighter or the like adjacent to the external ignition member 5, or alternatively by drawing the ignition member against a friction surface. Via the ignition duct 6, the ignition member 5 activates the ignition charge 4, which ignites the combustion charge. When the combustion charge is burning, such temperatures are generated adjacent to the tip of the oxygen lance, i.e. fully 1000 degrees Celsius, that the oxygen lance is ignited. In the embodiment described above, the ignition is initiated from outside by the external ignition member. It can be mentioned, however, that the ignition can be initiated internally by the reaction which supplied oxygen can produce with an initiation charge fitted in the sleeve, and in this context reference is especially made to Swedish patent SE C2 521 801. Regardless of igniter type, with or without a fuse, the ignition is realized by means of a previously known igniter 1 by pressing the oxygen lance 9 into the igniter when the igniter is in contact with a rigid object in order that the lance tip 8 shall make contact with the ignition charge and create the ignition.

An igniter 1 according to the invention and represented in side view with an oxygen lance 9 is shown in Figure 2. The interior of the igniter can be structured according to that which is described with reference to Figure 1, or according to some other similar known igniter. For loosenable securement of the tip 8 of the oxygen lance 9 in the igniter 1, a securing mechanism is provided. In this case, the mechanism consists of a tension spring in the form of a helical spring 11 and a locking device in the form of a locking ring 12. The locking ring is slipped over the oxygen lance and the helical spring is fixed at its one end in the locking ring and at its other end in the sleeve of the igniter and here, more specifically, in the, relative to the oxygen lance, rear end face 13 of the sleeve 2. The securing mechanism here ensures that the lance tip 8 is pressed with suitable strength against the ignition charge 4. The stage of arranging the igniters in contact with a rigid object, which stage forms part of previously known ignition processes, has thus been eliminated.

In order to achieve suitable biasing of the securing mechanism, according to a simple embodiment the helical spring 11 and the shell surface 14 of the sleeve 2 can be provided with markings which indicate the force of the bearing contact of the oxygen lance against the igniter. In a simple variant, a bar 15 on the helical spring, which bar is brought into position directly opposite a bar 16 on the shell surface 14 of the igniter, can indicate a suitable bearing force. Alternative and more sophisticated load-indicating means can also be included.

The principle for the igniter is now that, in an initial ignition process when oxygen is supplied without the oxygen lance having been ignited, the securing mechanism detains the oxygen lance in the igniter. Once the oxygen lance ignites, the securing mechanism will be exposed to considerable forces resulting in the release of the igniter 1 from the oxygen lance 9. This release process is achieved without the need to involve any human hand. The ignition process is thus configured such that it is suitable for the robotized handling of oxygen lance ignition and subsequent machining, such as cutting or drilling. The invention is not limited to the embodiments described above by way of example, but can be subjected to modifications within the scope of the following patent claims .