DE2720793A1 - PROCESS AND DEVICE FOR PERFORMING THERMOCHEMICAL QUICK START - Google Patents

Description

PATENT Attorney DIPL.-INC. GERHARD SCHWAN

OFFICE: “000 MÜNCHEN 83 ■ ELFENSTH.ASSE 32 2720/93

L-1O617-1-G

UNION CARBIDE CORPORATION 270 Park Avenue, New York, N.Y. 10017, V.St.A.

Method and device for performing thermochemical quick starts

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TELEPHONE: 0811/6012039 CABLE: ELECTRICPATENT MUNICH

■ "i

The invention is generally concerned with the thermochemical removal of metal from a workpiece surface, a process commonly referred to as "flaming". In particular, the invention relates to a method for performing quick starts or flying starts in scarfing operations. In the present case, a flying start is to be understood as the practically instantaneous initiation of a thermochemical reaction on a workpiece which moves at its normal scarfing speed compared to the scarfing machine, ie a speed between approximately 6 and 45 m / min. The speeds at the lower end of this range are used when scarfing cold workpieces, while the speeds at the upper end of this range are used for scarfing warm workpieces.

It is known to initiate a scarfing reaction by the metallic workpiece is preheated to its melting or ignition temperature, which is usually done with the help of a Relatively small area directed preheating flames happens before an inclined one on the weld pool Scarfing oxygen flow is inflated. The flame oxygen flow has a twofold task: on the one hand, it should bring about a thermochemical reaction with the metal; on the other hand it is intended to blow away the metal that has undergone the reaction, thereby exposing fresh metal for the scarfing reaction.

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It has long been known (e.g., US Pat. No. 2,205,890) to use metal rods to provide quicker starts in hand-flaming operations. In this case the workpiece must
stand still; the Flömmer must be skilled accordingly,
both to set the duration of the scarfing oxygen flow and to keep the burner and the rod at a suitable angle. It is also known (US Pat. No. 2,309,096) to initiate mechanical scarfing reactions with wires or rods.
The scarfing starts described there are, however, also
only possible with stationary workpieces.

It is known to carry out flying starts with the aid of metal powder (US Pat. No. 3,216,867) or by using a current-fed electrode (US Pat. No. 2,513,425 and 3,658,599). Powder starts are due to the rapid wear and tear of the
Powder feed unreliable; therefore, as well as the cost of the metal powder, powder starts are not satisfactory. Carrying out starts with the supply of electrical power is associated with relatively complex problems.

Transmitted electric arcs, where the workpiece is part of the electrical circuit, make one
electrical contact with the moving workpiece is required. In the case of non-transmitted electric arcs, in which the workpiece is not in the electrical circuit, it is necessary to place the electrode extremely close to the workpiece surface

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bring in enough heat to deceive and on in this way the workpiece is heated to the ignition temperature. This is because of space restrictions as well therefore impractical because the extremely strong spattering of the scarfing reaction would destroy the arc torch.

More recently, it has been found (U.S. Patents 3,966,503 and 3,991,985) that flying starts can be performed by bringing the metal surface to be flamed into contact with a hot wire. The hot wire will by the heat of the preheating flames of the scarfing unit or brought to ignition temperature by an external heat source. It has been shown that this procedure is successful in cases can be performed that require multiple spot flaming operations; however, it is necessary to provide a number of wire feed units corresponding to the number of scarfing units.

So far it has always been necessary to use an auxiliary material for example, metal powder or wires to be used to bring the workpiece to the ignition temperature.

In the present case, the term high-intensity jet is intended to express that the oxygen flow rate passing through the spreading nozzle is greater than the oxygen flow rate through a scarfing nozzle of a corresponding width.

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The invention is based on the discovery that a high intensity laser beam be focused on a very small spot on a metallic workpiece to be flamed that is already being hit by an intense jet of oxygen or that is simultaneously with such a jet in Is brought into contact, at the very small spot for an instantaneous initiation of a thermpchemical reaction which is then taken to cover the full width of a spot flaming passage is spread, d. H. a width that is usually between 5 and 25 cm. It was known that a laser beam hits a small spot (0.1 to 1 mm in diameter and 1 mm to 0.1 mm deep) instantly Can bring melting temperature. What was unexpected, however, was the finding that such a small and flat area molten metal by means of a high intensity oxygen jet can be spread to the full width of the spot flaming cut. It was assumed that a jet of oxygen high intensity would blow away such a small amount of molten metal before the thermochemical Reaction is initiated, or that the oxygen jet would cool the stain so far that initiation the reaction is prevented.

There are basically two different types of lasers known, namely continuous lasers and pulsed lasers. As the name suggests, pulsed lasers emit their energy in the form of very short bursts of high intensity. Both

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It concerns quick starts of the type considered here As with a pulsed laser, it is about intermittent processes. Therefore, pulsed is preferred in the present case Lasers worked. It will be understood, however, that a continuous laser can also be used by is pulsed via a diaphragm or other equivalent measures. A continuous laser is preferably used in a modified one Embodiment of the invention provided.

The invention aims to provide a simple and reliable method and to provide a device which allows a quick start or a flying start on a workpiece without addition of auxiliary materials (e.g. powder or wire) or an electric arc. Individual It should be possible to make burr-free spot flame cuts on a metallic workpiece immediately without it the use of auxiliary materials or electric arcs requirement. In the course of a one-time run over the On the workpiece surface, several arbitrarily arranged selective scarfing cuts should be initiated immediately the surface of a workpiece that moves at normal scarfing speed. Besides a method and a device are to be created that allow immediate or flying scarfing cuts to be made, without there being a high intensity jet of oxygen needed to spread the starting molten bath.

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A method according to the invention for performing a thermochemical Quick starts on the surface of a ferrous metal workpiece is characterized in that

(a) a predetermined location on the surface where the reaction occurs is to begin, is brought into contact with a laser beam,

(b) a high intensity jet of oxygen gas at the site the surface while initiating an immediate scarfing reaction and formation of a weld pool is brought to impinge at the point and

(c) a high intensity jet of oxygen continued to impinge is brought on the weld pool until the weld pool has expanded to a predetermined width.

A device for performing a quick start is characterized according to the invention by a scarfing machine with a scarfing unit with means which allow a preheating flame and a scarfing oxygen flow to escape in the direction of a workpiece to be flamed; an oxygen spreading nozzle mounted on the scarfing machine and seated in front of the scarfing unit, which is inclined at its outlet end in such a way that a high-intensity oxygen jet is formed at an angle to the workpiece surface at a predetermined distance in front of the scarfing oxygen flow, and one on the

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Scarfing machine seated laser with an associated optical system for focusing a laser beam on the workpiece surface.

After the weld pool is spread out to its preselected width the quick start is complete. The propagating oxygen beam can then be left on and used to perform the scarfing reaction; he can but can also be switched off and a different flow of oxygen can be used brought to impinge on the expanded weld pool at an acute angle to the workpiece surface to take over and carry out the scarfing reaction. The type of scarf cut required determines the type of scarfing oxygen flow that is provided to to take over the scarfing reaction from the spreading jet.

According to a modified embodiment of the invention is a method for making an instant flame cut on the surface of a metallic workpiece characterized in that

(a) for relative movement between the workpiece and a Scarfing oxygen gas flow is provided and simultaneously in order to

(1) to form a heated stretch of desired Length across the surface with respect to it

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Direction of movement brought at least one laser beam to impinge on the workpiece surface is, the heated path is generated by the fact that the laser beam is a series of points on the surface to its oxygen ignition temperature brings, and

(2) to initiate an instant flame cut along the Stretch, a flow of scarfing oxygen is brought to impinge on the heated stretch, and that

(b) the flow of scarfing oxygen is continued until the desired Cutting length is generated.

According to this modified embodiment of the invention the scarfing device is characterized by

(A) a scarfing nozzle arrangement, by means of which a controlled Scarfing oxygen flow onto the surface of something to be flamed Workpiece can be straightened,

(b) a device that allows relative movement between the nozzle arrangement and the workpiece, and

(C) a laser arrangement, by means of which to form a heated distance of the desired length transversely to the surface with respect to the direction of movement at least

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a laser beam can be brought to impinge on the workpiece surface, the laser beam causing a sequence of points on the surface heated to their oxygen ignition temperature and the heated stretch near the Center line projection of the scarfing oxygen flow the workpiece surface.

When using this modified embodiment, the preferred method is to heat the workpiece surface to its oxygen ignition temperature by means of a laser in that a continuous laser beam is adjusted in such a way that the beam is a continuum of points across meets the surface of the workpiece.

The term "quick start" as used herein is intended to include both flying starts and starts in which there are none between the workpiece and the scarfing device Relative movement takes place until the laser beam comes into contact with the preselected point. At the moment of contact, however, the normal scarfing speed is started immediately (without waiting in the known manner for the formation of the weld pool), so that the start takes place while the workpiece and scarfing device move against each other. The feed motion would not be immediate initiated when the laser beam hits, the oxygen beam would be within a very short period of time Form a hole in the workpiece. It goes without saying that the

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relative movement can be done by either touching the workpiece surface is moved in relation to a stationary scarfing device, or vice versa.

The term "scarfing oxygen flow" is intended to be used in the present case an oxygen gas flow can be understood, which obliquely on the workpiece surface is straightened and sufficient Intensity has to thermochemically form a metal surface layer to be removed, usually to a depth of about 1 to 8 mm, with a scarf cut at least 25 mm wide. Scarfing oxygen flows are preferably flat, however, they can also be circular or of a different shape.

A single burr-free spot flame cut can be carried out, by directing an inclined, planar flow of scarfing oxygen gas onto the molten bath, the intensity of which gradually increases in the direction of the edges of the flow is reduced in order to reach zero intensity at the side edges of the nozzle opening from which it emerges. A section is obtained, the width of which is smaller than the width of the outlet opening. Such a scarf cut can be implemented with nozzles as described in DT-OS 2 638 3O4.

If a selective spot scarfing of the entire surface of a workpiece is to be carried out in a single pass

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the scarf cuts not only be free of burrs, but also in are formed in such a way that adjacent cuts neither overlap nor excessively high bulges or deep flutes arise between the cuts. This requires the possibility of side by side at the weld pool to allow adjacent scarfing oxygen streams to escape, whose flow intensity gradually decreases in the direction of their edges and each of which makes a scarf cut generated that is at least as wide as the outlet in question. Nozzles for carrying out such Scarfing cuts are described in U.S. Patent 4,013,486. When these scarfing units run over the workpiece at normal scarfing speed, they can be used in a preselected manner can be switched on and off to any arbitrary distribution of flaws on the workpiece surface to flare out.

If a conventional scarfing process is to be carried out, can this is done by using a sloping, flat Scarfing oxygen flow, the flow intensity of which is substantially uniform over the full width, from a conventional one rectangular nozzle is pointed out at the weld pool. In such a case, the scarfing offers a quick start the advantage that the scarfing reaction can be initiated on a workpiece when this is with the scarfing units comes into appropriate alignment without slowing down or stopping the workpiece or the scarfing units

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the need to get the flame reaction to begin, like this is necessary when using conventional preheating flames. The quick start allows the scarfing process to come into contact with the device To begin the workpiece.

The invention is explained in more detail below on the basis of preferred exemplary embodiments. In the enclosed Drawings show:

Fig. 1 is a side view from which the method and the device used for performing a single burr-free spot flame cut with a quick start accordingly the invention can be recognized,

Fig. 2 is an end view of the scarfing oxygen nozzle

opening according to line 2-2 of Fig. 1,

3, 4 are schematic representations which, viewed from above along the line 3-3 of FIG. 1, show the Reveal the sequence of reactions that occur on the workpiece when performing a quick starts according to the invention take place,

Fig. 7 is a perspective view of a loading for carrying out the method according to the invention

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agreed device mounted on a boom for remote control purposes is,

8 and 9 modified embodiments of the device according to Fig. 7,

Fig. 10 is a perspective view of another

preferred embodiment of the invention, in which several adjacent scarfing units are intended to be used in a single pass for a selective multi-cut spot flaming to ensure the full width of the workpiece with quick start,

11 shows a modified embodiment of the laser arrangement according to Fig. 10,

Fig. 12 is an end view of the scarfing units

ten scarfing oxygen nozzles used according to FIG openings,

13 is a plan view of the arrangement according to FIG

Fig. 1O, from which it can be seen how with With the help of the method according to the invention several spot flaming cuts with quick start in a single pass over the full factory

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be carried out piece width,

14 is a side view showing a modified one Embodiment of the method and the device can be seen in which no High intensity oxygen beam is required

15 shows an end view (without scarfing unit) of the arrangement 14, which shows a preferred embodiment of the use of a laser reveals a sequence of points on the surface of a workpiece one after the other to heat them to their oxygen ignition temperature,

16 shows a modified embodiment for heating the surface of the workpiece using a laser, and

Fig. 17 shows the shape of a scarf cut obtained

when the arrangement of FIG. 16 for Performing a flying start is used.

In the embodiment according to FIG. 1, there is a laser unit 1 with a focusing lens 4 either on the scarfing machine or

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mounted away from this and arranged so that a laser spot the surface of the workpiece W at the point A hits, d. H. the point at which the scarfing reaction should begin immediately before the fault location. It is also a Oxygen spreading nozzle 2 is provided, which is a simple round nozzle with a bore of 1 to 5 cm. The nozzle forms melt pools approximately in width 5 cm to 25 cm. At its outlet end, the nozzle 2 is at such an angle with respect to the workpiece surface inclined that the projected center line of the oxygen jet emerging from the spreading nozzle 30 hits the workpiece surface at point B, hereinafter referred to as the oxygen impact point. The point A can be in a range from a position before point B to a position up to the point C is behind point B. The point C is around the projection of the inner diameter of the spreading nozzle 2. A scarfing unit 3 has conventional upper and lower Vor ^ heat blocks 12 and 13, which are equipped with a number of Vorwärmflammenauslaß 14 or 15 for premixed or post-mixed preheating flames and with appropriate gas passages can be provided. Is worked with post-mixed preheating flames, which is with a view to the greatest possible Safety is preferable, exits the outlets 14 and a fuel gas, which after ignition by mixing with a slow stream of oxygen burning the scarfing oxygen nozzle slot 16 leaves from the bottom 17 of the upper

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Preheating block 12 and the top 18 of the lower preheating block 13 is formed. The slot-shaped oxygen nozzle 16 ends in an outlet opening 19. Around a single burr-free To produce a spot flame cut, the opening 19 is shaped in the manner illustrated in FIG. 2. oxygen and fuel gas are the scarfing unit 3 in the named manner supplied via feed lines 20 and 21, respectively.

The device according to FIG. 1 operates as follows: First, the preheating flames emanating from the scarfing unit 3 are ignited by letting fuel gas escape from the rows of preheating outlets 14 and 15 and supplying a weak oxygen gas stream through the opening 19. These preheating flames indicated at 22 reach the workpiece surface and are deflected upwards and backwards. When the defective area of the moving workpiece W to be flame-out reaches a point just before the point B, a high-intensity oxygen jet is emitted from the nozzle 2 and made to strike the workpiece surface at the point B. When the defective area reaches point A, the laser beam is pulsed, as a result of which the relevant spot is immediately brought to the ignition temperature and a scarfing reaction is initiated immediately. The oxygen jet leaving the nozzle 2 has the effect that the small molten bath formed by the laser pulse is expanded very quickly to its full width, whereupon this oxygen jet is switched off and the one emerging from the opening 19

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Scarfing oxygen flow to point D on the workpiece surface is directed to its scarfing flow rate is increased to the reaction of the spreading nozzle to take over. The scarfing oxygen flow remains switched on, as long as the scarfing cut is to be continued.

The steps that follow the ignition of the preheating flames emitted by the scarfing unit 3 can be automated and controlled, for example, via a series of clock sequence timers, relays and solenoid valves so that a flamer or an appropriate signal initiates the sequence of steps explained above, which is then carried out automatically . A second signal is required to end the cut by switching off the scarfing oxygen gas flow or reducing it to a value just sufficient to keep the preheating flames burning. In this state the device is ready to carry out another spot scarfing process immediately.

According to a modified embodiment of the sequence of steps explained above, the scarfing oxygen flow is switched on at the same time as the spreading jet. The latter has a much greater force or impact force and therefore controls the course of the thermochemical operation; that is, it causes the melted spot to spread. When the oxygen jet of the spreading nozzle is switched off, the scarfing oxygen flow takes over the reaction very gradually.

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borrowed and steady, but nevertheless quick.

Fig. 2 shows the scarfing nozzle opening 19 in the scarfing unit 1 is used to form a single burr-free scarf cut. Other scarfing nozzles that are suitable for the present purposes are explained in detail in DT-OS 2,638,304. It should be emphasized that a critical one A feature of such a nozzle is that the cut produced has a smaller width than the nozzle itself. This is necessary to achieve a burr-free spot flame cut. At the same time, however, this makes it impossible to use such nozzles side by side with another such nozzle because of the parallel cuts obtained between the individual cuts a non-flamed one Would leave surface area. As a result, such nozzles are only suitable for the formation of individual burr-free cuts. Fig. 2 let the upper and lower preheating blocks 12 and 13 recognize, which correspond to the rows of upper and lower preheating gas outlets 14 and 15, respectively. At both ends of the opening 19 of the oxygen nozzle there are triangular inserts 25 which cause the intensity of the edge parts of the opening 19 to leave Oxygen flow gradually decreases, d. H. those on the workpiece surface transmitted impact force is lower.

While in the arrangement according to Fig. 1 point A is behind point B, the mutual position and distance of the-

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These points are varied so that the point A can be from about 10 cm in front of the point B to a distance behind the point B, which is determined by the projection of the inner diameter of the nozzle 2 (see point C). The point C therefore depends on the size and shape of the nozzle 2. The mutual distance between points A and B is preferably chosen so that point A is approximately 1 cm in front of point B. The most favorable range for the distance between point A and B depends on the angle cc at which the oxygen jet is directed onto the workpiece surface; it is also a function of the size of the jet nozzle. The angle oc can vary between approximately 30 ° and 80 °; the angle is preferably between 50 ° and 60 °. If the angle oC of the nozzle is 30 and a round nozzle with an inner diameter of 2 cm is used, the distance between A and B should be between 0 and 8 cm. When using a nozzle of the same size and an angle ot of 80 °, this range is 0 to 3 cm. Point C, which is the intersection of the projection of the rear of the spreading nozzle and the workpiece surface, forms the limit value for the distance that point A can lie behind point B if a flying start is to be guaranteed.

The sketches according to FIGS. 3 to 6 show how quick starts are carried out in accordance with the method described here or flying starts. It is important to

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emphasize that the sequence of steps illustrated in FIGS. 3 through 6 represents the reaction which takes place in about 1 second.

Fig. 3 applies to the time at which the laser beam the Has reached point A, d. H. the point at which the spot flaming process should begin. The arrow indicates the direction in which the workpiece W is traveling at a speed of approximately 15 m / min runs. At the same time, the oxygen emerging from the spreading nozzle 2 causes the workpiece surface to ignite. As a result, the area 23 surrounding the point A is melted. The rapid or instantaneous start has begun.

FIG. 4 shows the same area about 1/4 s later than FIG. 3. While the steel workpiece is moving in the direction of the arrow Moved further, the molten bath 24 begins to fan out under the influence of the oxygen jet from the spreading nozzle spread out.

Fig. 5 shows the error range approximately 1/2 second later than Fig. 3. The area 25 'shows the weld pool, which on the workpiece W moved on due to the continued Has spread the escape of oxygen from the spreading nozzle 2. When the weld pool is at its maximum width of about 25 cm, the nozzle 2 leaving oxygen shut off; the flow rate of the scarfing oxygen leaving the scarfing unit 3 is increased, to take over the scarfing reaction. The flame oxygen flow

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detects the weld pool and continues the flame cut in area 26. The area 26 contains both molten liquid Metal as well as slag on the top of unflamed Stole; it can be clearly distinguished from the continuously melted bath area 25 '.

The manner in which the reaction proceeds is in FIG. 6 which shows the reaction approximately 1 second later than FIG. Area 27 was flamed; the area 28 has melted, but no metal has yet been removed; is located within the area 29 a mixture of slag and molten metal on top of unflamed steel. While the surface of the metallic workpiece is located under the scarfing device moved through it, it goes through three clearly distinguishable stages. The first stage is an area of molten metal and slag on non-flamed steel. In the second stage there is only molten material Metal found. In the third stage, the area in question is flamed. To that illustrated in FIG. 6 At this point, the flow of oxygen is switched off; the scarfing unit 3 carries out a full-width scarfing cut. It is important to note that the width of the cut made by the scarfing nozzle is the same as that The width over which the spreading nozzle 2 has spread the molten bath. This is important to avoid a ridge formation to avoid.

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Fig. 7 shows a perspective view of the device
according to Fig. 1, which is mounted on a boom to the
Scarfing device both in the transverse direction across the width of the workpiece W and in the longitudinal direction along the
To be able to adjust the length of the workpiece. A
Horizontal frame part 31 is attached to a control pulpit 32 guided on rails. The pulpit 32 contains the
Controls for the operation of the device, including the laser controls and the controls for the
Spreading nozzle 2 leaving oxygen as well as the oxygen and the combustion gases which are supplied to the scarfing unit 3 via the supply lines 2O and 21, respectively. The pulpit 32 is in
can be moved in the lateral direction along the workpiece W on rails 33. A toothed rack 34 attached to one of the rails does not stand with a rack seated under the pulpit 32
illustrated, motor-driven pinion in mesh, making the entire, mounted on a boom
Flämmanordnung and the pulpit along in the desired manner
the rails 33 can be moved. The one consisting of the scarfing unit 3, the nozzle 2 and the laser arrangement 5
Flame assembly is attached to a carriage 37 which runs up and down on a plate 38 which in turn is attached to a housing 40. With the aid of a motor 39, the flame arrangement is raised in a controlled manner via a combination of toothed rack and pinion, which is not illustrated
and lowered; the rack in question is attached to the plate 38.

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The flame arrangement and the housing 40 can be adjusted across the width of the workpiece W with the aid of a motor- driven pinion 35 which cooperates with a rack 36 fastened to the frame 31.

With the aid of the device illustrated in FIG Defects distributed on the surface of the workpiece are selectively flamed out by the device with aligned with the defect and then longitudinally over the point of failure is moved away. The area 41 represents represents a typical spot flame cut made by means of the illustrated apparatus.,

FIG. 8 shows a modified arrangement of the laser head 5. In this figure, components corresponding to the components according to FIG. 7 are provided with the same reference numerals. The laser itself is located at a remote location. By using an optical arrangement, in this case a 90 prism, the laser beam is directed onto point B from the right side of the workpiece. In the case of the arrangement according to FIG. 9, the nozzle 2 is directed from the right side of the workpiece W to the point B, so that the molten bath is driven in the direction of the left side of the workpiece in front of the scarfing unit 3. This arrangement allows the starting molten bath to be spread more rapidly over a wider area, so that wider scarfing cuts can be made than when using a

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equally sized nozzle arrangement in the case of the figures 7 and 8 is the case. It goes without saying that the nozzle 2 is also on the left or in any intermediate position may be appropriate. It is also possible to work with a combination of two such nozzles; with With the help of the training according to FIGS. 7 or 8, the starting can be started take place; by means of the arrangement according to FIG. 9, the molten bath can be expanded.

Fig. 10 shows a plurality in perspective of scarfing units equipped with nozzles to cover the full width of a workpiece W in a single pass selectively flame in a plurality of cuts performing quick starts or flying starts. The scarfing units 51, a laser head 52 with a plurality of optical arrangements and spreading nozzles 53 are fixedly mounted on a movable carriage 54 which is on rails and 56 runs and can be moved via a rack and pinion drive. The rails 55 and 56 are on rail supports 57 permanently mounted. The laser assembly 52 may have a housing H, which by means of nitrogen or another Gas is purged. In the housing H are partially transparent and partially reflective at predetermined intervals 9O prisms P arranged. The prisms allow the energy of the laser beam to be split up and into several spots to distribute on the workpiece surface. Instead, you can 90 mirrors are used, which are optional in the way

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of the beam pivoted in or pivoted out of this to direct the beam to the desired spot. Any optical system can be used either with beam splitting or optional beam deflection is working. The overall arrangement of the scarfing units sitting next to each other, suitable for a flying start can run over the full length of the workpiece W, so that the full width can be selectively flamed at normal flaming rate by each of the flaming assemblies is operated separately as an option. Although with the one in figure 10 illustrated device the workpiece stands still and the scarfing device runs over the workpiece, it is possible, and in some cases cheaper, to proceed in reverse, i.e. with a scarfing device at a standstill to work, under which the workpieces pass on rollers that are driven at normal scarfing speed are.

11 shows a further modification of the device according to FIG Fig. 10. In this embodiment, a mirror M directs the from the laser head L coming laser beam to a plurality of fixed mirrors F, which are mounted so that that of these Reflecting the captured beam is directed onto the workpiece surface W via a focusing lens G.

When with the devices illustrated in FIGS selective multi-cut spot flaming processes

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leads where two or more cuts from each other overlapping duration must be made, which can be initiated at different times, at which in any case, however, the speed due to the relative movement is determined between the workpiece and the scarfing arrangement, there can be no break or reduction in the scarfing speed tolerated from the moment the first cut was started until the last cut was completed is. The reason for this is that a pause uncontrollably triggers one from an adjacent unit the cut that has just been made. With others Words, if, for example, the arrangement had to be slowed down to the preheating usual in known systems, would be an adjacent arrangement in which the scarfing oxygen is turned on, form a deep hole in the workpiece. It follows that with a selective multi-pass spot scarfing process no slowdown can be tolerated and that for a proper implementation of a Such a procedure, an immediate start or a flying start is of such crucial importance.

In addition, it is essential that this method does not cause scarfing cuts that are either of a or overlap adjacent unit to be flamed Cause burrs or bulges between adjacent scarfing cuts. This requirement is met by providing suitable scarfing oxygen nozzles for a group passage

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be, d. H. several flame units arranged side by side with nozzles of the type illustrated in Fig. 12.

Fig. 12 shows the end face of the scarfing units, which for the group passage scarfing nozzles according to FIG. 10 are provided. These nozzles each include a number of upper ones and lower post-mixing fuel gas outlets 61 and 62, which are above and below an outlet opening 63 for the Sitting scarfing oxygen. The opening 63 is typically about 6 mm high and 20 cm wide. Your edges are through End wall parts 64 partially completed. These are typically about 3 cm long in the area of the lower edge; their greatest height is 4 mm; they have a bevel cut with an interior angle of approximately 10. Such End wall portions 64 are provided at each end of each scarfing oxygen port 63 to block the flow of oxygen in the direction gradually reduce to the edges of each unit, but without completely closing the edge of the unit, as in the case of the opening illustrated in FIG. Case is. Generate openings of the type shown in FIG a scarf cut on the workpiece, the width of which is less than the width of the opening from which the oxygen is drawn exits, whereas the group passage opening 63 according to FIG. 12 leads to a section which, although in the direction becomes flatter towards its outer edges, but has at least the same width as the opening 63 itself.

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Fig. 13 is a plan view showing how the devices according to FIGS. 10 and 11 work when a workpiece with flying starts in several cutting paths is to be selectively spot-flamed. In Fig.iü a plurality of scarfing units 51 sitting next to one another are shown, each of which has an oxygen spreading nozzle 53 and an optical System with prisms P and a focusing lens inside the tube T and each of which with oxygen and fuel gas is supplied.

The defective areas on the surface of the workpiece W to be spot-flamed are designated 81, 82, 83, 84 and 85. When the moving group of adjacent scarfing units (now denoted by 71, 72, 73, 74 and 75) comes into contact with workpiece W, unit 74 must make a flying start when it reaches forward end 86 of area 84 achieved. The unit 74 must remain on until it arrives at the rear end 87 of the area 84. Unit 74 is then shut down while units 71 and 72 are started on the fly. While the group of scarfing units is moving over the workpiece, unit 72 remains on until it reaches the rear end of defective area 82. It is then blocked either by the flamer or on the basis of a mechanical or electrical signal, while the unit 71 remains switched on. The unit 74 is turned on again to

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men of area 85 to begin. When the scarfing unit group approaches the beginning of the area 83, the unit 73 is switched on, while the unit 74 at the end of the Area 85 is switched off. The unit 71 is switched off, when the end of range 81 is reached. The unity remains during the entire passage of the stain flame 75 switched off, as there were no errors in the zone of the workpiece over which this unit ran.

14 to 17 show a modified embodiment, with no high-intensity oxygen jet and no spreading nozzle required are.

14 is a laser unit 1 with a focusing lens 4 on the frame of the scarfing machine (not shown) mounted (it could also be remotely located) and arranged so that the laser beam R meets the surface of the workpiece W at point A, where the scarfing cut is to begin. The scarfing unit 3 typically has conventional upper and lower preheating blocks 12 and 13, respectively, which are equipped with a series of premixing or post-mixing preheating outlets 14 and 15 as well as appropriate gas passages can be provided. The scarfing oxygen nozzle slot 16 is from the bottom 17 of the upper preheating block 12 and the top 18 of the lower preheating block 13 are formed. The slit-shaped oxygen nozzle 16 ends in an outlet opening 19. To the

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Initiate thermochemical reaction, point A can be slightly lie in front of the area of the rectilinear projections of the surfaces 17 and 18 on the workpiece surface limited or coincide with this area. Oxygen and fuel gas are fed to the scarfing unit 3 in a known manner via the feed lines 20 and 21, respectively.

The apparatus of Fig. 14 operates as follows. First of all, the preheating flames emanating from the scarfing unit 3 ignited by allowing fuel gas to escape from the rows of preheating outlets 14 and 15 and a weak one Oxygen gas flow through the opening 19 is supplied. The preheating flames are indicated at 22. The scarfing device and the workpiece are moved towards one another. Immediately before the defective area on the surface to be flamed of the workpiece W reaches the point A, the from the Opening 19 exiting oxygen flow to the scarfing oxygen flow rate turned up. Simultaneously with this or shortly thereafter, the laser beam R is switched on, which leads to The consequence is that point A immediately shows the oxygen ignition temperature reached and an immediate scarfing cut at point A begins. The laser beam is then across the workpiece surface directed with respect to their running direction, whereby the scarfing reaction spreads to the desired width by following the path heated by the laser. The scarfing oxygen flow remains for the

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Desired scarfing length switched on while the laser beam can be switched off as soon as the scarfing cut the Has reached the target width.

The relative movement can be started after a flame reaction of the desired width has been initiated, if no flying start is desired. A flying start is a start that takes place while the workpiece is moving and move the scarfing device towards one another at normal scarfing speed.

15 and 16 show two embodiments according to which a section of the desired length on the workpiece surface can be heated to the oxygen ignition temperature by means of a laser. 15 shows an end view of the arrangement according to FIG. 14 along the line 2-2; the scarfing unit itself is not illustrated. The laser 1 and its optical system are switched on and pivoted through the angle β so that the laser beam R heats a continuous sequence of points. As a result, a distance on the metal workpiece surface between points A and B is brought to the oxygen ignition temperature. Instead of rotating the laser, the beam R can also be directed optically so that it traverses the distance between points A and B.

A modified solution for heating a section on the workpiece surface is illustrated in FIG.

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The laser beam is shifted between points A and B by moving the reflecting mirror M or lens 4 along the path of the desired flame cut into position M ¹ and 4 '(with the aid of an arrangement not shown).

The laser used in the case of Figures 15 and 16 is preferably a continuous laser. However, a pulsed laser can also be used. In this case, a series of closely spaced Areas between points A and B brought to the oxygen ignition temperature. The individual areas or Spots flow together when the oxygen is turned on. It is understood that other optical arrangements can be used to achieve the same result; this can also be done with more than one laser, among other things to be worked.

Fig. 17 shows the shape of a scarf cut when it is made a flying start using a single laser and the arrangement of FIG. 15 or 16. The Start of the cut begins at point A and continues to point B, while the scarfing device and the Workpiece W are moved against each other. Area 1O1 represents the scarfing section.

This modified embodiment can apply to the same

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Purposes such as those with a high intensity oxygen jet working arrangement. Such applications include conventional flame cuts a planar flow of oxygen, d. H. the flaming of the whole Surface, the implementation of individual burr-free spot flame cuts, the width of which is less than, as well as wide as or larger than the width of the scarfing nozzle, as well as the implementation of spot flame cuts by several Scarfing units are assembled together to provide a spot flame in the group passage.

example

The necessary to carry out the explained procedure Laser energy depends on variables such as the scarfing speed, the material composition and the temperature of the workpiece, oxygen flow rate and purity and the like away. In the following, however, a practical embodiment will be described in more detail for the purpose of explanation.

A system of the type illustrated in FIG. 1 was used used. The width of the scarfing unit was 15 cm. Oxygen was in an amount of 570 Nm / h through the opening 19 passed through. The flow rate of the fuel gas was 40 Nm / h. The workpiece was opposite the scarfing unit moved at 14 m / min. The oxygen spreading nozzle had a circular cross section and an inside diameter

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of 2 cm. The nozzle angle with respect to the workpiece was 50 °. Oxygen was passed through the spreading nozzle in an amount of 850 Nm / h. The laser acted it is a pulsed Nd-YAG solid-state laser. Of the The diameter of the beam emerging from the laser was 1 cm. The beam divergence was 5 mrad. The laser pulse had a width of 11.0 / µs. The laser energy was 5O joules. The laser spot had a diameter of 2.0 mm. The laser spot (A) was 1 cm in front of the projection (B.) of the center line the spreading nozzle. A 50 cm focal length lens was used to focus the beam on a spot.

The flame of the scarfing unit was ignited during operation; the Relative movement between the scarfing unit and the workpiece has been initiated. A signal to begin the spot flaming started the flow of oxygen passed through the spreader nozzle; than the full flow is reached was, the laser was pulsed, causing one in the steel molten stain formed and the thermochemical Reaction started immediately. About 1/2 second after the laser pulse, the flow of oxygen from the spreading nozzle was gradually closed so that 3/4 of a second after the impulse the flow through the spreading nozzle reached zero. Of the Scarfing oxygen flow was turned on so that at least 50% of full flow rate was achieved when the laser was pulsed. The flame oxygen then held the flame

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cut upright until this was triggered by a predetermined signal ended. The width of the cut formed was 15 cm; the cut was 3 mm deep. the Temperature of the steel was 20 ° C. It was one low carbon steel. Natural gas was used as the fuel gas.

If desired, the illustrated method can be used in the manner be carried out that the flame of the scarfing unit is ignited by the weld pool, which by means of the laser or the spreading nozzle is formed.

Various preferred embodiments have been described above explained. It should be understood, however, that in terms of arrangement Numerous modifications can be made to the various assemblies or the sequence of steps. For example it is possible to use a continuous laser beam because that formed by such a beam Line would be scorched out as the scarfing reaction progresses. Two or more oxygen jets can also be provided, which can emerge from two or more nozzles of different shapes and sizes in order to use a laser generated melt stain to spread to any desired stain flame width. If necessary or desired, can also use two or more laser heads. While the above explanation is based on the thermochemical flaming of ferrous metal bodies is directed, it is further understood that

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any metal body can be processed which allows thermochemical flaming using oxygen .

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Claims (33)

Expectations . Method of performing a thermochemical quick start on the surface of a metallic workpiece to be flamed, characterized in that (a) a predetermined location on the surface where the Scarfing reaction should begin, with a laser beam brought into contact with this point on their Bring ignition temperature; (b) a high intensity jet of oxygen gas at the site the surface with the initiation of an immediate scarfing reaction and the formation of a melt pool the point is brought to impact; and (c) a high intensity beam of oxygen continued to impinge is placed on the weld pool until the weld pool has expanded to a predetermined width, 2. The method according to claim 1, characterized in that a ferrous metal workpiece is used as the workpiece. 3. The method according to claim 1 or 2, characterized in that that to carry out a flying start the relative movement between the workpiece and to carry out the 709846/1 1 1 U ORIGINAL INSPBJTED Process steps used device takes place before and during the process steps without interruption at the normal scarfing speed. 4. The method according to any one of claims 1 or 2, characterized in that that the relative movement between the workpiece and the used to carry out the process steps Device with normal scarfing speed is initiated when the laser beam with the point in Touch comes. 5. The method according to any one of the preceding claims, characterized in that a single laser beam Laser energy pulse is used. 6. The method according to claim 3, characterized in that the laser beam hits the workpiece surface at one point touches the one behind the point of impact of the high-intensity oxygen flow up to 10 cm in front of this point. 7. The method according to claim 6, characterized in that the point of impact located behind the oxygen impact point of the laser beam is determined by the projection of the inner diameter of the nozzle from which the oxygen flow is generated exit. 709846/1 1 1 U 8. The method according to claim 3, characterized in that the high-intensity oxygen jet according to the method step (b) is aimed at the location from such a position that that from the central axis of the beam and the line of movement of the workpiece surface included angle is between 30 ° and 80 and the weld pool is parallel to the direction of relative movement is spread. 9. The method according to claim 3, characterized in that the high-intensity oxygen jet according to the method step (b) is aimed at the location from such a position that that from the central axis of the beam and traps formed on the workpiece surface Angle is between 30 and 80 and the weld pool spread out perpendicular to the direction of relative movement will. 10. The method according to any one of the preceding claims, characterized marked that in addition (d) the surface is flamed by applying a flat Flame oxygen flow brought to impinge on the weld pool at an acute angle to the surface will. 7098A6 / 11U 11. The method according to claim 1O _1, characterized in that for the formation of a single burr-free Fleckflämmschnittes, the width of which is smaller than the width of the outlet opening for the scarfing oxygen stream, the intensity of the flat scarfing oxygen stream in the direction of the edges of the stream gradually to the intensity zero the side edges of this outlet opening is reduced. 12. The method according to claim 10, characterized in that the intensity of the planar flame oxygen flow in The direction towards the edges of the current gradually diminishes, but at an intensity value above zero the side edges of the opening from which the scarfing oxygen flow exits is held, whereby a burr-free Spot flame cut is formed, the width of which is equal to the width of the outlet opening and none excessively high projections or deep recesses between simultaneously and in the same way produced, adjacent cuts can arise. 13. The method according to claim 10, characterized in that to form a conventional scarf cut with a planar flow of oxygen is worked, the over the entire width of the associated outlet opening has substantially uniform intensity. 709846/1 1 U 14. The method according to any one of claims 11 to 13, characterized characterized in that the width of the cut formed is equal to or greater than the width of the initial one Melting bath is made. 15. Device for initiating a thermochemical reaction on the surface of a metallic workpiece, characterized by a scarfing machine with a scarfing unit with means that a preheating flame and a flame oxygen flow in the direction of a to be flamed Let the workpiece emerge, an oxygen spreading nozzle mounted on the scarfing machine and located in front of the scarfing unit, which is inclined at its exit end in such a way that a high-intensity oxygen beam under an angle to the workpiece surface in a predetermined Distance is formed in front of the scarfing oxygen flow, as well as one sitting on the scarfing machine Laser with an associated optical system for focusing a laser beam on the workpiece surface. 16. The apparatus according to claim 15, characterized in that a feed device is provided for provides a relative movement between the scarfing machine and the workpiece. 17. The device according to claim 15 or 16, characterized 7Π98Α6 / 1 IU draws that the laser is a pulsed laser. 18. Device according to one of claims 15 to 17, characterized characterized in that the laser is a solid-state laser. 19. Device according to one of claims 15 to 18, characterized in that the laser is an Nd-YAG crystal. 20. Device for initiating a thermochemical reaction on the surface of an iron workpiece, characterized by a scarfing machine with several scarfing units, which direct a preheating flame and a scarfing oxygen flow onto a workpiece to be flamed, several oxygen diffusion nozzles mounted on the scarfing machine, each of which sits in front of a scarfing unit and is inclined at its exit end in such a way that a high-intensity oxygen beam is formed at an angle to the workpiece surface and at a predetermined distance in front of the scarfing oxygen flow, as well as with at least one laser arranged on the scarfing machine with an associated optical system, by means of which several focused laser spots on the Workpiece can be formed. 21. The device according to claim 20, characterized in that the optical system of the laser several partially permeable and partially reflective devices 709846 / 11U has, in a laser housing in predetermined Intervals are arranged in such a way that the energy of the laser beam can be split and applied to several spots on the Workpiece surface is distributable. 22. The device according to claim 20, characterized in that the optical system of the laser has a plurality of mirrors which are arranged in a laser housing at predetermined intervals such that the mirrors can each be selectively introduced into the laser beam path or brought out of this path to the beam to point at a preselected spot on the workpiece surface. 23. The device according to claim 20, characterized in that several lasers are arranged on the scarfing machine, to which an optical system is assigned, by means of which several laser spots can be formed on the workpiece are. ·. 24. Method for making an instant flame cut on the surface of a metallic workpiece, characterized in that (a) a relative movement is provided between the workpiece and a flow of scarfing oxygen gas, and at the same time 709846/1114 (1) at least one laser beam is brought to impinge on the workpiece surface in order to form a heated section of the desired length transversely to the surface with regard to the direction of movement, the heated section being generated by the laser beam bringing a sequence of points on the surface to its oxygen ignition temperature brings, and (2) to initiate an instant flame cut along the route brought a flow of scarfing oxygen to impinge on the heated route will, and that (b) the flow of scarfing oxygen is continued until the desired cutting length is generated. 25. The method according to claim 24, characterized in that the heated path is generated by rotating a continuous laser beam across the workpiece surface. 26. The method according to claim 24, characterized in that the heated path is formed by a pulsed Laser beam is rotated across the workpiece surface. 709846/11 U 27. The method according to any one of claims 25 to 26, characterized characterized in that the scarfing oxygen flow is flat is trained. 28. The method according to claim 24, characterized in that the heated path is formed by a reflective Mirror and a beam focusing lens across be moved over the workpiece surface. 29. Scarfing device, characterized by (A) a scarfing nozzle arrangement, by means of which a controlled Flaming oxygen flow can be directed onto the surface of a workpiece to be flamed, (b) a device that allows relative movement between the nozzle arrangement and the workpiece, and (c) a laser assembly by means of which for training a heated stretch of the desired length across the surface with respect to its direction of movement at least one laser beam can be brought to impinge on the workpiece surface, the The laser beam heats a sequence of points on the surface to its oxygen ignition temperature and the heated stretch near the center line pro- 7098A6 / 11U jection of the scarfing oxygen flow on the workpiece surface lies. 30. The device according to claim 29i, characterized in that that a continuous laser is provided as the laser arrangement. 31. The device according to claim 29, characterized in that a pulsed laser is provided as the laser arrangement is. 32. Device according to one of claims 29 to 31, characterized by means of rotating the laser beam along the route. 33. Device according to one of claims 29 to 31, characterized by a device for optically adjusting the laser beam along the route. 709846 / 11U