HU176173B - Process and apparatus for thermochemical shelling - Google Patents

Abstract

The present invention relates to the thermochemical scarfing of metal workpieces. The present invention seeks to provide a method for scarfing the surface of a metal workpiece that provides acceptably short preheat times for scarfing relative cold workpieces without being subject to flashback and without requiring adjuvant material. In accordance with the present invention post-mixed scarfing pre- heating flame is produced by discharging fuel and oxygen from separate ports to impinge forming acute included angle. The flame is stabilized with a low-intensity stream of oxygen, directed in same general direction as the flame, close to but not passing through the point of impingement. <IMAGE>

Description

Thermochemical peeling generally occurs in three phases. These phases are:

1. Attach the workpiece to the deburring unit.

2. preheating, whereby a metal melt is formed on the surface of the workpiece, and

3. performing thermochemical peeling or oxygen planing by applying a peeling oxygen beam to the workpiece surface and creating a relative displacement between the workpiece and the peeling unit or peeling units.

The present invention relates to the second of the described technological steps, namely preheating the workpiece and forming the molten metal.

Preheating of workpieces has been the subject of numerous prior patents. They describe various methods for performing the preheating required for thermochemical peeling. No. 2,267,405. For example, U.S. Pat. The two types of gas are mixed in the nozzle and ignited when the gas mixture leaves the nozzle. This solution is commonly referred to as premixing. The basic disadvantage is that the gas mixture escaping is explosive and has a tendency to re-ignite, that is, to explode inside the nozzle. This blast or potential explosion may not only damage the blowers but also endanger the operating personnel.

No. 2,356,197. U.S. Pat. No. 5,122,115 discloses a solution whereby oxygen and combustible gas are mixed only prior to discharge from the nozzle. Although this solution is safer than the method described above, the apparatus operated in this way still presents a risk of explosion. In fact, if the outside of the nozzle becomes clogged, for example droplets of molten metal, while leaving the oxygen inlet and combustible gas outlets open, the gas mixture is formed inside the nozzle and is extremely explosive.

No. 3,234,331. U.S. Pat. No. 4,123,195 describes a preheater in which the mixing of oxygen and combustible gas occurs outside the discharge nozzles, so that an explosion is completely excluded. However, the efficiency of the preheating flame produced in this way is quite limited. With this device, only a workpiece that has already been heated can be effectively prepared for thermochemical peeling, otherwise the workpiece can be heated to the desired temperature in a very long time.

No. 3,752,460. U.S. Patent No. 4,198,121, discloses a solution known as the so-called. reduces the warm-up time by using an oxygen trap. Although this solution is indeed more efficient than the previous one, being an improvement, it is not suitable for economically preheating cold workpieces.

A further similar solution is disclosed in U.S. Patent No. 3,966,503. US patent. The time required for this pre-heating is reduced by contacting a metal wire with a high intensity oxygen beam to the workpiece by means of a feed device and by means of which they rapidly form the metal melt. Using the present invention, preheating the workpieces for thermochemical peeling is virtually time-consuming, and in this respect is more efficient than the present invention. However, it has the disadvantage that it requires a separate unit for storing and feeding the starter wire. Therefore, its application is really economical only when it is necessary to start the thermochemical peeling very quickly.

From the foregoing it appears that until now no solution has been found which allows the workpieces to be preheated with sufficient speed during thermo-chemical peeling without using additional units or avoiding the risk of explosion. This essentially means that efficient preheating could not be achieved with relatively simple and inexpensive means.

It is therefore an object of the present invention to provide a process and apparatus that allows relatively rapid heating of the workpiece during thermo-chemical peeling without the need for additional aids or the risk of explosion.

The object of the present invention is to achieve the object of the present invention that, during peeling, during which at least a portion of the surface to be machined is preheated and heated to a flash point at one point, then the molten portion is incinerated with a peeling oxygen stream and the peeling and moving the workpiece relative to one another, expelling at least one preheating oxidizing gas jet and at least one combustible gas jet from a separate nozzle so as to close an acute angle to one another, and then emitting and emitting a low-intensity oxidizing gas jet over the surface of the workpiece. After the preheated surface of the workpiece has reached the ignition temperature, a peeling oxidizing gas jet is emitted at an acute angle to the preheated surface of the workpiece, and at the same time a relative displacement is created between the peeling oxidizing gas jet and the workpiece surface.

The stabilizing oxidizing gas jet can be blown off at an acute angle or 10 ° to 90 ° to the preheating flame.

The stabilizing oxidizing gas jet may be blown through the preheating flame or through the preheating flame.

Preferably, the stabilizing oxidizing gas jet and the shelling oxidizing gas jet are blown out of a common nozzle and formed as a nozzle nozzle.

It is advisable to emit the preheating oxidant gas jet and the combustible gas jet at an angle of 5 to 50 ° to each other.

The process of the invention may be carried out by means of an apparatus comprising a preheating flame generating unit, a decanting oxidizing gas discharge nozzle unit and optionally a relative displacement unit between the decanting oxidizing gas jet and the workpiece, wherein the preheating flame producing unit a nozzle or an oxygen jet of a preheating oxidizing gas or of a nozzle of a preheated oxidizing gas, or a nozzle or gas nozzles for directing a flammable gas jet, having a nozzle for preheating oxidizing gas or a nozzle for preheating oxidizing gas.

In the apparatus, the axis of the stabilizing oxidizing gas outlet nozzle may pass through or outside the intersection of the gas nozzle (s) and the axes of the oxygen nozzle (s).

The axis of the stabilizing oxidizing gas outlet nozzle may be inclined from 0 to 170 ° with the resultant axis of the gas nozzle and the oxygen nozzle.

Preferably, the preheating oxidizing gas discharge nozzle and the stabilizing oxidizing gas discharge nozzle are formed as a single nozzle nozzle located between the lower heating block and the upper heating block of the decortication unit. The gas jets and the oxygen jets are at an angle of 5 to 50 °.

The gas nozzles and the oxygen nozzles are preferably arranged in parallel rows, and may be arranged in a variety of ways: they may be located in the upper heating block or the lower heating block, or may be arranged in both heating blocks.

As used herein, the term oxidizing gas refers to a gas or gas mixture comprising an oxidizing medium. The oxidizing gas is preferably oxygen of commercial purity, which for simplicity will be called oxygen. Of course, the process according to the invention can also be carried out using other oxidizing gas. It can also be used as an oxidizing gas, for example a gas mixture containing 99% or less oxygen. Generally, however, good results can be obtained using gas mixtures containing at least 99% oxygen. However, the preheating oxidizing gas need not contain this amount of oxygen. A gas mixture such as air containing up to 21% oxygen is suitable for this purpose. Of course, the lower the oxygen content of the preheating oxidant gas, the longer the preheating takes.

As used herein, preheating is the process of heating the surface of a workpiece to be peeled to a temperature at which the workpiece material is sufficient in an oxidizing atmosphere.

Further details of the invention will be illustrated by way of example in the drawings. In the drawing it is

Figure 1 is a side elevational view of a preferred embodiment of the apparatus of the invention, a

Figure 2 is a sectional view taken along the line 2-2 of the apparatus of Figure 1, a

Figure 3 is an enlarged view of a portion of the apparatus of Figure 1, a

Figure 4 shows the favorable location of the metal melt relative to the oxygen beam when starting the peeling operation on a flat surface workpiece;

Figure 5 shows the beginning of the peeling operation at the corner of a workpiece, a

Fig. 6 shows the preheating times achieved by conventional and methods according to the invention, a

Figure 7 illustrates an embodiment of the apparatus according to the invention in which the gas discharge nozzles for the preheating flame are located in the lower heating block of the husk assembly;

Fig. 8 shows a solution where the stabilizing oxygen nozzle and the scaling oxygen nozzle are formed separately,

Figure 9 is a view 9-9 of the solution of Figure 8, a

Figure 10 is also a front view of the solution of Figure 8 in another embodiment, a

Fig. 11 is a side view detail of an embodiment of the apparatus according to the invention in which the preheating flame and the stabilizing gas jet intersect in common focus,

Fig. 12 is a side view detail of an embodiment similar to that of Fig. 3, where the stabilizing flame and the preheating gas intersect at a common focus;

Figure 13 is a side view of a detail of an embodiment where the gas jet to be stabilized passes under the focus of the preheating flame and

Figure 14 is an embodiment similar to that of Figure 13, but with the stabilizing gas jet passing through the focus of the preheating flame.

Figures 1, 2 and 3 illustrate a preferred embodiment of the present invention. The peeling unit 3 consists of 1 upper heating block and 2 lower heating blocks and 4 sole parts. The upper heating block 1 and the lower heating block 2 are commonly referred to as preheating blocks in conventional equipment, since the preheating flame is blown out of these blocks. However, in the embodiment of the device according to the invention shown in Figures 1, 2 and 3, the preheating flame only flows from the upper heating block 1. Between the upper heater block 1 and the lower heater block 2, a slot nozzle 16 is formed from which a flat jet of oxygen flows out. The slot nozzle 16 is bounded by the lower surface 20 of the upper heating block 1 and the upper surface 21 of the lower heating block 2. In the lower heating block 2, gas nozzles 19 are formed which are connected to gas lines in the usual way. These gas lines are not shown in the drawings. Oxygen and combustible gas are fed to the nozzles via the peeling unit 3 via a known distribution system, which is not shown for simplicity.

The base part 4 lies on the surface of the workpiece W during peeling and provides guiding of the nozzles at a distance Z from the workpiece W.

Peeling is initiated by igniting a molten metal formed on the surface of workpiece W. Ignition is effected by means of a flat jet of oxygen emitted from the nozzle 16 which flows at an acute angle to the workpiece surface W. During peeling, relative movement between the workpiece and the peeling unit must be ensured.

According to the invention, gas nozzles 17 and oxygen nozzles 18 are formed in the upper heating block 1. These gas nozzles 17 and oxygen nozzles 18 are connected by conduits through which gas flows into the apparatus. Figure 2 clearly shows that the oxygen nozzles 18 are located above the gas nozzles 17. The apparatus may also be configured such that the gas nozzles 17 are located above the oxygen nozzles 18, but this is less favorable than before. In general, it is expedient to place the gas nozzles 17 which emit preheating combustible gas between the oxygen nozzles 18 which emit preheating oxygen and the nozzle 16 which emits stabilizing oxygen.

The equipment shown operates as follows. A preheating oxygen jet 9 is discharged from the oxygen nozzles 18 and simultaneously a preheating gas jet 10 is exited from the gas nozzles 17. This produces a combustible gas mixture where the preheating oxygen jet 9 and the gas jet 10 meet at intersection 30 (see Figure 3). At the intersection 30, a preheating flame 14 is formed which comprises a low intensity zone and a high intensity zone 12. During the tests, it has been found that the high intensity zone 12 can be extended so that its peak 27 is exactly at the surface of the workpiece W to provide a longer and more efficient preheating flame 14. This is provided by a low-intensity jet of oxygen, which is called towards the preheating flame 14 at the intersection 30. Preferably, the stabilizing oxygen beam passes through, but does not touch, the intersection 30.

Although the term "intersection" is used throughout the description, it is obvious that it is an intersection area rather than a radius or a flame, so that its intersection does not have a geometric sense but only an intersection area. However, for the sake of simplicity, the term intersection will continue to be used.

The stabilizing oxygen beam 15 is emitted from the slot nozzle 16. Conventional valves in the apparatus ensure that low-intensity stabilizing oxygen jets 25 can be emitted from the nozzle 16. The intensity of the stabilizing oxygen jet 15 is substantially lower than that of the decortical oxygen jet used in the process, which is also emitted from the nozzle 16.

The stabilizing oxygen beam 15 is blown out toward the preheating flame 14. Its axis preferably has an acute angle with the axis of the preheating flame 14. The preferred angle between the preheating flame and the stabilizing oxygen beam 15 is shown in Table 2 below. Figures 1 and 3 clearly show the angle between the axes of the preheating flame 14 and the stabilizing oxygen beam 15. It is also advantageous for the process that the oxygen jet axis of the preheater 15 is parallel to the axis of the gas jet 10. This is also clearly shown in Figures 1 and 3.

The gas jet 10 and the preheating oxygen jet 9 are preferably enclosed at an acute angle. The angle must be greater than 0 ° and less than 90 °. The preferred angle range is from 5 to 50 °. The angle of 15 ° proved to be the most advantageous for the tests.

The intensity of the stabilizing oxygen jet 15 emitted from the nozzle nozzle 16 must be substantially less than the intensity of the preheating oxygen jet or the combustible gas jet. The outlet velocity of the stabilizing oxygen beam 15 is preferably about 10% of the outlet velocity of the preheating gas jets.

In the event that the preheating flame is not stabilized as described above, the high intensity zone 12 of the preheating flame 14 would be so short that preheating would not be possible at a sufficient rate. In this case, the distance Z would have to be reduced, meaning that the high intensity zone of an unstabilized flame would have to be brought so close to the workpiece surface W that the splashing metal particles would render normal operation impossible.

The flammable gas discharged from the gas nozzles 19 mixes with the oxygen discharged from the nozzle nozzle 16 and actually maintains the peeling reaction. In fact, these flames need not be used during preheating, but the use of the gas nozzles 19 during preheating prevents the gas nozzles 19 from becoming blocked and thus technologically advantageous.

After creating the necessary metal bath at point B, as shown in Figure 3, the oxygen intensity from the nozzle 16 is increased and the peeling is started. At the same time, we begin to move the workpiece relative to the scavenging oxygen beam. During the peeling operation, the preheating oxygen jet 9 and the gas jet 10 are not completely stopped, but their intensity is significantly reduced. Maintaining these actually helps the husk reaction to take place. Above the gas nozzles 17 and the oxygen nozzles 18, a baffle 28 is provided in the upper heating block 1 which prevents the low intensity flame from extinguishing during peeling.

Many parameters need to be considered when designing the apparatus of the invention. However, these variables are not independent of each other. When designing conventional husking equipment, the following parameters are usually fixed:

1. G is the angle between the peeling oxygen jet and the workpiece surface,

2. X - the thickness of the 16 nozzles,

3. V - distance of peeling unit 3 from workpiece surface,

4. · υ - width of the 3 shelling units (see Figure 2),

5. the quality of the combustible gas,

6. the quality of the oxidizing gas.

After recording the above values, other characteristics of the husking process can be determined. These characteristics can be selected within a certain range while recording the values.

Table I shows typical fixed parameters commonly used in conventional thermochemical peeling or oxygen planing.

Table I

G Peeling angle 35 °

X is the slot nozzle thickness 5.6 mm

Z The height of the peeling unit is 25.0 mm

U is the width of the peeling unit is 270.0 mm

II. Table IV shows the characteristic values for the process according to the invention under the boundary conditions set forth in Table I.

II. The values shown in Table 1 are also dependent on each other. Thus, if the value of one of the parameters is significantly different from the advantageous value, the other parameters will be further away from the optimal value. Of course, if we change the value of any of the fixed parameters shown in Table I, then the values of Table II are changed. The limit ranges for the preferred ranges shown in Table 1 are also substantially changed. It will be apparent to those skilled in the art that, based on the two tables presented, a satisfactory result can be obtained using a practically infinite combination of parameters.

The gas nozzles 17 and the oxygen nozzles 18 are preferably circular in cross-section, but other designs may be functional. The device can also be equipped with square or polygonal nozzles. The unit is operable with a single wide preheating oxygen-emitting nozzle nozzle and a single preheating flammable gas-emitting nozzle nozzle, although this design is not very favorable. The device operates significantly more efficiently if multiple nozzles are formed and arranged in parallel rows, as shown, for example, in Figure 2 or Figure 10.

If multiple nozzles are formed in the debarking unit, it is desirable to maintain a constant Y distance between the nozzles. It should also be ensured that a suitable gas nozzle 17 is positioned opposite each of the oxygen nozzles 18. This design ensures the smoothest and fastest preheating, although other designs can produce results.

The angle F of the preheating flame 14 enclosed with the workpiece surface, i.e., the preheating angle is preferably between 40 and 55 °, if the distance Z of the peeling unit 3 to the workpiece surface is 25 mm. If the angle F is greater than 55 °, the preheating flame 14 will easily burn a hole in the workpiece. However, if the angle F is less than 40 °, the peak 27 of the preheating flame 14 and thus the high intensity zone 12 will be too far from the workpiece surface so that a short preheating time is not expected. The angle F is also the value of I and

II. is determined by the parameters shown in Table. The preferred ranges shown there provide a favorable preheating angle, but there are working combinations outside of the ranges shown.

II. spreadsheet

specific It's a good value Allowed range Gas nozzle diameter 1.0 mm 0.7-1.7 mm Preheating gas speed 1.7 Nm ³ / h 1-3.5 Nm ³ / h Nozzle distance Y (Figure 2) 6.0 mm 3-16 mm Diameter of oxygen nozzle 1.6 mm 1-2 mm Oxygen preheating speed 3.7 Nm ³ / h 1.5-6 Nm ³ / h Oxygen Nozzle Division Y 6.0 mm 3-16 mm Angle D between preheating oxygen nozzles and gas nozzle shafts (Figure 3) 15 ° 5- 50 Distance of gas nozzles from bottom plate of upper heater block (distance 26 in Figure 3) 10 mm 3-15 mm Angle of preheater oxygen nozzle and workpiece angle (H in Figure 3) 50 ° 40 ° -75 ° Distance of intersection 30 from nozzles (distances 31 and 32 in Figure 3) 15 mm 3 to 22 mm Distance between nozzle rows (29 in Figure 2) 4 mm 1.5-6 mm Speed of stabilizing oxygen flow during preheating per cm of nozzle width 6 Nm ³ / h 3-10 Nm ³ / h

In a preferred embodiment of the process of the invention, the preheating gas nozzles and the oxygen nozzles are located as close to each other as possible without the gas jets mixing within the unit and causing an explosion hazard.

Figure 4 illustrates a preferred embodiment of the apparatus according to the invention in which the metal melt D formed upon initiation of the peeling is at the intersection of the axis of the oxygen jet 15 exiting the nozzle 16 and the surface T of the workpiece W. As shown in Figure 4, the jet of oxygen 15 flows to the trailing edge C of the molten metal B as the peeling unit moves in the direction of arrow J. This location of the metal melt B allows it to be blown out by the gas jet and moved forward in the direction of peeling, thereby preventing burrs or ribs on the machined surface.

If peeling is to be started at the corner of workpiece W, as shown in Figure 5, the oxygen jet 15 from the nozzle 16 may be directed to any part of the molten metal, since this is not a horizontal surface at start-up and ♦ 5 on the E surface.

7-14. Figures 1 to 5 show various embodiments of the present invention that achieve a relatively good result, although they are not optimal designs. However, all the solutions presented provide relatively fast preheating and eliminate the risk of explosion.

Figure 7 is a side view of the solution 55 shown in Figures 1, 2 and 3, except that the gas nozzles 17 and the oxygen nozzles 18 are located in the lower heating block 2. The operation of the apparatus is substantially the same as that of the apparatus shown in Figures 1, 2 and 3.

Figures 8 and 9 show a solution in which, in addition to the slot nozzle 16, the apparatus comprises a plurality of oxygen jets 16 'for emitting a stabilizing oxygen beam. The preheating oxygen jet 9 from the oxygen nozzles 18, the gas jet 10 from

17 gas nozzles. Preheating is done by the preheating flame. The preheating flame 14 is stabilized by the stabilizing oxygen jet 15 'flowing out of the auxiliary nozzle nozzle 16'. The stabilizing oxygen beam 15 'is blown near the intersection 30 in the direction of the preheating flame 14. The gas nozzles 17 and the oxygen nozzles 18 and the auxiliary oxygen nozzle 16 'are formed in the upper heating block 1. However, there is no obstacle to placing them in the lower heating block 2.

After preheating with the aid of the apparatus, a jet of oxygen is discharged from the slot nozzle 16 towards the workpiece surface. The flammable gas flowing out of the gas nozzles 19 during the peeling operation helps maintain the peeling reaction.

Figure 9 is a front view of the solution shown in Figure 8 with circular nozzles. Figure 10 shows the same solution except that another 16 "auxiliary slot nozzle is provided beside the nozzle 16. As we have said, other nozzles may be designed as nozzles, but this is less favorable than shown.

Fig. 11 is a side view of an apparatus in which, as shown in Fig. 8, additional oxygen nozzles 16 'are provided in addition to the slot nozzle 16 to provide a stabilizing oxygen beam. Thus, the nozzle nozzle 16 serves only to emit a scavenging oxygen beam. All. However, in the embodiment shown in FIG. 6B, the stabilizing oxygen beam 15 'flowing from the auxiliary oxygen nozzles 16' passes through the intersection of the preheating oxygen beam 9 and the gas jet 10.

Tests on the apparatus have shown that it is desirable to provide baffles 28 and 28 'in order to increase the range within which the rate of preheating and stabilizing gas jets can be selected to produce a stabilized flame. A particularly advantageous arrangement may be provided if the gas nozzle 17 is not positioned between the oxygen nozzle 18 and the auxiliary oxygen nozzle 16 but at the edge of the upper heating block 1 and directly adjacent to the baffle 28. However, it has also been found that the apparatus operates without the baffles 28 and 28 '.

Figure 12 shows an apparatus for emitting both the scavenging oxygen jet and the stabilizing oxygen jet from the slot nozzle 16, similar to the embodiment shown in Figure 3. THE

12, however, the stabilizing oxygen beam 15 passes through the intersection 30 of the preheating oxygen beam 9 and the gas beam 10. Of course, the intersection 30 must be located above the workpiece.

As previously mentioned, the stabilizing oxygen beam 15 is blown out in the direction of the preheating flame 14. This is advantageous in terms of the efficiency of preheating, but functionality is not precluded if the stabilizing oxygen beam 15 is blown out or perpendicular to the axis of the preheating flame.

Figure 13 also shows a side view of another embodiment. In this case, the stabilizing oxygen beam 15 'flows not in the direction of the preheating flame 14, but in part opposite to it. Here, the preheating oxygen jet 9 and the gas jet 10 meet at a point of intersection 30 as described above and form a preheating flame. The axis 22 of the preheating flame 14 intersects at 23 the axis of the stabilizing oxygen beam 15 '5. It can be seen that the angle A between the axis 22 and the axis of the stabilizing oxygen beam 15 'is less than 90 °. If the angle A was greater than 90 °, the stabilizing oxygen beam would be blown outward in the direction of the flame.

In summary, according to the invention, the stabilizing oxygen beam can be blown out in two ways. If the angle A in FIG. 13 is less than 90 °, the stabilizing oxygen beam 15 is directed toward the preheating flame; if this angle is greater than 90 °, the stabilizing oxygen beam is by definition blown toward the preheating flame.

Tests showed that preheating 20 was satisfactory when the stabilizing oxygen beam, called the preheating flame, formed an angle of A = 10-90 ° with the axis of the preheating flame. The position of the preheating flame 14 will of course be influenced by the position of the nozzles, the direction of the jet and the velocity of the gas jets.

The stabilizing oxygen beam 15 'of FIG. 13 reaches the preheating flame before the intersection of the preheating oxygen beam 9 and the gas beam 10. However, satisfactory results can be obtained even when the preheating oxygen beam is directed behind the intersection 30.

Figure 14 is a view similar to Figure 13, wherein the stabilizing oxygen beam 15 'passes through the intersection 30. This design 35 is also suitable for rapid preheating.

Although the factors controlling the course of preheating are quite complex, an attempt will now be made to explain the rapid preheating of the process and apparatus of the present invention.

In our studies, it has been observed that if a preheating flame is formed that is not connected to a stabilizing oxygen beam, the low intensity zone of the preheating flame is relatively large and the high 45 intensity zone is rather small. Occasionally, no high intensity zone was created. In addition, it has been found that the unstabilized preheating flame easily vibrates.

⁵⁰

When attempting to enlarge the high intensity zone of the unstabilized preheating flame, the flame increases by increasing the velocity of the gas jets; its vibration increases. A further disadvantage of increasing the speed is 55 h ° 8y the flame breaks out of the nozzles and goes out after a while. In addition, it has been found that the baffles somewhat prevent the flame from falling off as the speed increases and delay the extinction.

In contrast, if the preheating flame is stabilized by a low-intensity oxygen jet according to the invention, the flame creates an extremely rapidly growing intense zone and the vibration is also eliminated. The preheater. By increasing the velocity of the gas jets 65, the flame cannot be cut off from the nozzles, and speeds at which the unstabilized flame is extinguished can be used.

Advantages of the preheating flame stabilized according to the invention are as follows.

Because the oxygen that provides the flame stability is blown out in a low-intensity jet, it does not interfere with the mixing of the preheating oxygen and preheating gas jets outside the nozzles. At the same time, it provides oxygen for the combustion to occur and also surrounds the high intensity zone with oxygen. This oxygen envelope provides extremely good conditions for the flame to propagate towards the nozzles so that the unburned gas portions near the nozzles can be burned.

On the other hand, the stabilizing oxygen beam forms a protective sheath around the preheating flame, which prevents air from reaching the flame. This is advantageous because the air does not provide good conditions for the flame to propagate, which, in the absence of an oxygen envelope, causes the flame to become unstable and to fall off the nozzles or, in some cases, to go out.

It is noted that the solution shown in Figure 3, wherein the stabilizing oxygen beam is blown in the direction of the preheating gas, has proved particularly advantageous.

In order to blow the stabilizing oxygen jet towards the preheating flame, as previously defined, the axis of the nozzle emitting the stabilizing oxidant gas must close at an acute angle with the resultant axes of the gas nozzle and the oxygen nozzle. Conversely, if the stabilizing oxidizing gas jet is to flow opposite the preheating flame, as shown in Figure 13, the axis of the stabilizing oxidizing gas-emitting nozzle should close at an angle of 90-170 ° with the resultant axis of the gas jet and oxygen jet.

The following examples illustrate the effectiveness of the process of the present invention.

Thermochemical peeling, i.e. oxygen planing, was performed according to the solution shown in Figure 4 under laboratory conditions. The apparatus was constructed with the fixed parameters given in Table 1 and the favorable parameter ranges of Table 2 were also observed. The results are shown in Figure 6. In the diagram, the curve X represents the preheating according to the process of the invention. The horizontal axis of the diagram shows the time required for preheating and the vertical axis the initial temperature of the workpiece; The curve Y is shown in U.S. Pat. No. 3,752,460. And the curve Z is shown in U.S. Pat. No. 3,231,431. Shows the preheating time of conventional peeling according to U.S. Pat.

It is clear from the diagram that the present invention provides much more favorable preheating times. Even for workpieces having an initial temperature greater than 200 ° C, the pre-heating time required by the process of the invention is half that of the more conventional conventional process. For workpieces having an initial temperature of less than 200 ° C, the preheating time according to the invention is several times higher by the conventional method. It is also important that the pre-heating of a workpiece that is colder than 25 ° C in 20 seconds cannot be solved by conventional means. However, according to the invention, even a completely cold workpiece does not require 20 seconds to preheat.

The embodiment shown in Figure 11 was thermochemically peeled. Table H1 gives the optimal parameters for thermochemical peeling in this case. Of course, these values, as well as the values shown in Table 11, are interdependent, so changing one value implies changing the other.

The values of the parameters not shown in Table 111 are the same as those shown in Table 11.

Finally, the IV. Table 13 shows the optimal parameters for operating the apparatus shown in Figure 13.

Of course, the IV. The parameters given in Table 1 are also dependent on each other and cannot be changed independently. The IV. The values of the parameters not shown in Table 11 are the same as those of Table 11.

From the foregoing, it can be seen that the process and apparatus of the present invention are capable of preheating the workpieces in a much shorter time than conventional prior to thermochemical peeling. The essence of the presented solutions is to stabilize the preheating flame with an oxidizing gas jet, thereby enabling the preheating time to be reduced.

Claims (21)

Patent claims: CLAIMS 1. A process for thermochemical peeling comprising preheating at least a portion of the surface to be machined and heating it to a flash point at a single point, burning the molten portion with a peeling oxygen stream, and maintaining the combustion during processing, and moving the peeling oxygen jet and workpiece. characterized in that - venting at least one preheating oxidizing gas jet and at least one combustible gas jet from separate nozzles so as to close at an acute angle with each other and to overlap the workpiece surface, and - emitting a low-intensity oxidizing gas jet to stabilize the preheating flame, - after the preheated surface of the workpiece has reached the ignition temperature, a scavenging oxidizing gas jet is applied at an acute angle to the preheated surface of the workpiece, and - at the same time creating a relative displacement between the decaying oxidizing gas jet and the workpiece surface. Priority: 26/09/1977 The method of claim 1, wherein the stabilizing oxidizing gas jet is blown out at an acute angle to the direction of the preheating flame. Priority: 26/09/1977 III. spreadsheet specific It's a good value Allowed range is the value of angle C 25 ° 5-90 ° the distance of the intersection from the nozzles 15 mm 3 to 22 mm diameter of the stabilizing oxygen nozzle 2 mm 1-6 mm the velocity of the stabilizing oxygen beam 1.3 Nm ³ / h 1-4 Nm ³ / h ARC. spreadsheet specific Valid values Allowed range the distance of the intersection from the nozzles 15 mm 3 to 22 mm diameter of the stabilizing oxygen nozzle 2 mm 1-6 mm the velocity of the stabilizing oxygen beam 1.3 1-4 is the value of angle A 80 ° 10-90 ° 3. The method of claim 1, wherein the stabilizing oxidizing gas jet ^{41 is} blown out at an angle of 90 ° to 170 ° to the preheat flame. Priority: 03.07.1978 Fourth embodiment of the method according to claim 2 or 3, characterized in that the stabilizer ^{4 5 6 7 8} · oxidizing gas jet is blown past the preheating flame. Priority: 26/09/1977 Fifth embodiment of the method according to claim 2 or 3, characterized in that the preheat oxidizing gas jet is ejected from the preheating heat ke- ^5t restenosis. Priority: 03/03/07 6. A method according to any one of claims 1 to 6, characterized in that the stabilizing oxidizing gas jet and the shelling oxidizing gas jet are blown out of a common nozzle. Priority: ^5/6/1977 7. A process according to any one of claims 1 to 4, wherein the oxidizing gas is oxygen. Priority: 26.9.1977 6C 8. A method according to any one of claims 1 to 4, characterized in that the preheating oxidizing gas jet and the combustible gas jet are blown out at an angle of 5 to 50 °. Priority: 26.9.1977 65 9. A process according to any one of claims 1 to 5, characterized in that the combustible gas is at a rate of 1 to 3.5 N cubic meters per hour SCMH, the preheating oxidant gas is at a rate of 1.5 to 6 N cubic meters per hour SCMH, and the stabilizing oxidizing gas is flowed at a rate of 3 to ION cubic meters per hour SCMH per centimeter of nozzle height. Priority: 26/09/1977 10. Apparatus for thermochemical peeling, a unit having a preheating flame, a unit having a peeling oxidizing gas discharge nozzle and, if appropriate, a feed unit generating a relative displacement between the peeling oxidizing gas jet and the workpiece, characterized in that nozzles or pre-heating nozzles (18) for axially inclined gas jets or gas jets (18, 19) which close at an acute angle to the shafts of the gas jets (17, 19) and cut off outside the workpieces of the jets (17, 19) has an intensity stabilizing oxidizing gas discharge nozzle. Priority: 26/09/1977 An embodiment of the apparatus of claim 10, wherein the axis of the stabilizing oxidizing gas-emitting nozzle is the gas nozzle (17, 19) and lies outside the intersection (30) of the axes of the oxygen nozzle (18). Priority: 26/09/1977 12. An embodiment of the apparatus of claim 10, wherein the axis of the stabilizing oxidizing gas-emitting nozzle 5 passes through the intersection (30) of the axes of the gas nozzle (17, 19) and the oxygen nozzle (18). Priority: 03.07.1978 An embodiment of the apparatus according to claims 11 and 12, characterized in that the axis of the stabilizing oxidizing gas-emitting nozzle 10 is at an acute angle with the resultant axes of the gas nozzle (17, 19) and the oxygen nozzle (18). Priority: 26/09/1977 14. An embodiment of a payoff according to claim 11 or 12, characterized in that the axis of the stabilizing oxidizing gas-emitting nozzle is at an angle of 90-170 ° between the gas nozzle (17, 19) and the oxygen nozzle (18). of the axes. Priority: 20.3.1978 15. An embodiment of the apparatus according to any one of claims 1 to 5, characterized in that the preheating oxidizing gas discharge nozzle and the stabilizing oxidizing gas discharge nozzle are formed as a single slot nozzle (16). Priority: 26/09/1977 16. An apparatus according to claim 15, characterized in that the slot nozzle (16) is formed between the lower heating block (2) and the upper heating block (1) of the husking unit (3). Priority: 26/09/1977 17. A 10-16. Device according to any one of claims 1 to 3, characterized in that the gas nozzles (17, 19) and the oxygen nozzles (18) are formed at an angle of 5 to 50 ° to each other. Priority: 26/09/1977 18. 10-17. Device according to any one of claims 1 to 3, characterized in that the gas nozzles (17, 19) and the oxygen nozzles (18) are arranged in parallel rows. Priority: 26/09/1977 19. An embodiment of the apparatus of claim 18, wherein the gas nozzles (17) and the oxygen nozzles (18) are located in the upper heating block (1). Priority: 26/09/1977 20. An embodiment of the apparatus according to claim 18, characterized in that the gas nozzles (17) and the oxygen nozzles (18) are located in the lower heating block (2). Priority: 26/09/1977 21. An embodiment of the apparatus of claim 18, wherein the gas nozzles (17, 19) are disposed within the upper heater block and the lower heater block. Priority: 26/09/1977