DE10034806C1 - Workpiece de-burring method using laser radiation uses 2-stage process for reducing volume of edge burr and for providing required workpiece edge geometry - Google Patents

Abstract

The de-burring method uses laser radiation (2) directed onto the workpiece (1) for generating heat used for removal of the burr (4) along a workpiece edge in successive stages, respectively used for reducing the volume of the burr by relative movement between the workpiece and the laser radiation and for providing a required workpiece edge geometry using further relative movement between the workpiece and the laser radiation.

Description

The present invention relates to a method for Deburring a workpiece, in which by a Laser beam heat into the workpiece to be deburred is introduced to one along a workpiece edge running ridge at least in sections remove.

To carry out the generic method, especially in connection with metallic Workpieces, different removal mechanisms known.

DE 43 26 236 A1 relates, for example, to a method for deburring or breaking edges of workpieces as well a device for performing this method, it being provided that a laser beam is local directed the area of the edge of the workpiece and optionally along this. At the same time, a reaction medium against the Edge area of the workpiece, which at the temperatures in the range generated by the laser beam the material to be removed from the edge of the workpiece in an easily removable  Converts reaction product. The kinetic E The energy of the reaction medium is kept so low that the conversion of the material of the workpiece into the reaction product takes place "in situ" without the Reaction medium itself possibly for removal melted material could contribute. Due to the thermodynamic conditions, in particular due to the geometry-related heat conduction, ent stands a rounded edge shape, the shape of which is not through the travel strategy of the laser beam relative to the Workpiece, but only through the process pa rameter is determined. In the aforementioned disclosure Scripture is also stated that the procedural pa parameters can be set so that the reacti on product detaches itself from the workpiece. This is especially true especially possible if the reaction medium is oxygen or is an oxygen-containing gas, which the up melted material oxidized. This removal mechanism is also known as laser cutting.

Another known removal mechanism is the so-called called melt removal, where the ridge and edge melted with a low intensity laser the, the melt being removed with a gas jet becomes.

A third known removal mechanism provides that the material not only melted, but also a Part of the melt is evaporated. To such a Ver vapor, the energy density of the laser rays in the active site above the required Ab threshold. The evaporation rate increases  the melt with increasing energy density, whereby to Achieving particularly high energy densities using lasers who work in pulse mode.

All thermi performed with the help of a laser beam Common removal process has in common that heat in the workpiece to be deburred is introduced. In metallic materials becomes a so-called heat river zone formed. The type of microstructure in the heat affected zone and the size of the heat affected zone depend in particular on the material properties the amount of energy introduced, the duration of heat influence and the temperatures in the melt. The higher the Intensity and the shorter the radiation duration of the on set laser radiation, the smaller the size the heat affected zone. In addition to the properties of heat The zone of influence also comes from the achievable surface roughness ability to be of crucial importance. If a laser beam with a relatively low intensity used in this way is that a weld pool is created in the material low surface roughness can be achieved. When using pulsed laser radiation with high In In contrast, higher surfaces become higher causes roughness. Furthermore, when using Laser radiation with high intensity a vapor pressure testifies, which drives out the melt from the active site, whereby so-called melting ridges or secondary burrs can be generated.

When the melt of metallic materials solidifies again there is an increase in volume, so-called Caterpillars are formed. The cross section of a caterpillar is  the greater the larger the amount of melt produced. On The edge of the workpiece favors the formation of caterpillars because the increase in volume of the re-solidifying melt is possible in two dimensions. If that through the La Melting bath generated by radiation on a workpiece channel te exceeds a critical amount, it may work edge of the piece to form melt beads. there favor frequent irregularities of the Burrs the formation of such beads.

It follows from the above that the known gat Process according to deburring a workpiece in Dependency on the removal mechanism used cause different problems, but all of them that contribute to the high standards of education edge of the edge and the heat affected zone fig cannot be fulfilled.

Advantages of the invention

The fact that the method according to the invention for deburring a workpiece, in which heat is introduced into the workpiece to be deburred by a laser beam in order to remove a burr running along a workpiece edge at least in sections, comprises the following steps:

• a) Reduce the ridge volume by at least one Part of the ridge by a first relative movement o which is a first set of relative movements of Workpiece and laser radiation is removed; and  
• b) generating a predetermined workpiece edge quantity ometry by a second relative movement or a second set of relative movements of workpiece and Laser radiation,

wherein steps (a) and (b) are carried out in succession be, the laser beam can be according to the conditioned process step just performed so that overall an improved result he is aimed.

The following further step is preferably carried out after process steps (a) and (b):

• a) Smoothing the edge surface by a third relay tivotion or a third set of relative movements workpiece and laser radiation.

Laser is preferably used to smooth the edge surface low intensity radiation used, so probably pulsed as well as continuously working lasers can be used. Because of the low intensity the surface is preferably only remelted, without significant material removal. The laser power should be chosen that the thickness of the melt film is enough to be rough melting peaks and smoothing.

The relative movement or set of relative movements according to step (a) it is preferably carried out in such a way that the laser radiation is parallel to the workpiece edge  is going out of an irregular line through the Reduce the burr volume a regular To form residual ridge. Such a regular Remaining burr, can be processed without the undesirable fused pearls mentioned at the beginning become.

It is also conceivable that the relative movement or the set of relative movements according to step (a) is such is performed that the laser radiation along the Workpiece edge is guided to completely close the burr remove. With this procedure, however through step (a) in the area of Material of the workpiece located on the workpiece edge influenced by the processing, which is why this Offers procedure in particular if the generated by such a step (a) Workpiece edge has properties that on the subsequent process step (b) are coordinated.

It is considered particularly advantageous if that Reduce the burr volume according to step (a) a laser cutting process is performed. By such a laser cutting process can be under Regular residual ridge may be desirable easily generated. Performing a laser Cutting has the advantage that not all of it Burr volumes to be removed in this step evaporated must be what is energetically cheaper.

The energy density of the laser radiation is preferred on the workpiece surface during execution from step (a) to perform the laser  Cutting process conditioned and the laser radiation in the Essentially focused on the ridge, and the Laser radiation closes while performing the Laser cutting process with the workpiece surface Angle between 0 ° and 45 °, in whose plane the ridge essentially lies. Such a choice of this Winkels has the advantage that irregularly thick flags the burr does not adversely affect the deburring result affect, because in the case of an already separated or a flag that does not exist from the start Laser energy passes the workpiece.

To carry out process step (a), the Energy density of the laser radiation on the Workpiece surface preferably conditioned in such a way that there is a sublimation removal process results. Sublimating is understood in this Relationship between the phase transition of the material solid phase to the gaseous phase. At this transition a melt phase is formed, however can be relatively thin. The heat of sublimation is approximately equal to the sum of melting and Heat of vaporization. In the present case it has Sublimation removal process, also known as Evaporation is called the advantage that that Melting volume and the heat affected zone due to the high energy densities low or small can be held. This will increase the risk of reduced melt formation at the beginning and there can still be an adequate removal rate achieved what the efficiency of the operation supported.  

Also when carrying out process step (b) with certain specified workpiece Edge geometries can be beneficial if the Energy density of the laser radiation on the The workpiece surface is conditioned in such a way that in turn, an ablation procedure Sublimation basis results.

However, it can also be advantageous if the Energy density of the laser radiation on the Workpiece surface for carrying out the Method step (b) is conditioned in such a way that a reactive removal process results. On such a reactive removal process can for example, the laser cutting process was explained at the beginning and in which the Process parameters can be selected such that the oxidized melt becomes independent as an oxide chip takes off.

When process step (c) is carried out, the energy density of the laser radiation on the Workpiece surface preferably conditioned in such a way that the intensity is low. Because of the low The edge surface only becomes intense remelted without a significant Material removal is achieved, as is the case with smoothing is desired.  

To irradiate the entire edge surface and thus to smooth it out, it can be beneficial to To expand laser radiation, as a result of which a larger one Edge surface section can be edited at once can. Alternatively or in combination, the Relative movement or the set of relative movements are carried out in accordance with method step (c), that the full irradiation of the smoothing edge surface results. To generate the Laser radiation is particularly suitable Giant pulse laser system that also functions as a Q-switch Laser system is called such a system is particularly suitable for the energy density of the Laser radiation in process steps (a), (b) and - so far  performed - (c) differently and accordingly the respective requirements.

drawings

The invention is described below with reference to the associated Drawings explained in more detail.

Show it:

Fig. 1 shows a workpiece with an irregular ridge;

FIG. 2 shows an example of the position of the laser radiation to Gratfahne;

. FIG. 3a shows the workpiece of Figure 1 after the imple tion of step (a) with a regular Restgrat;

. FIG. 3b shows the workpiece tion according to Figure 1 after the imple of step (a), wherein the workpiece has a chamfer with recast;

. Fig. 4 shows the workpiece of Figure 1 after the imple of procedures steps (a) and (b), with a ver rounded edge of the workpiece; and

Fig. 5 shows the workpiece of FIG. 1 after the implementation of process steps (a), (b) and (c), with a rounded and smoothed workpiece edge of high surface quality.

Description of the embodiments

Fig. 1 shows a metallic workpiece 1 with a arranged in the region of the workpiece edge 3 irregular ridge 4 prior to carrying out the method according to the invention for deburring the workpiece.

FIG. 2 shows a preferred possibility for the position of the laser radiation 2 relative to the ridge 4 for the implementation of method step (a). The energy density of the laser radiation 2 is conditioned in order to carry out a laser cutting process and is essentially directed onto the ridge 4 . While the laser cutting process is being carried out, the laser radiation 2 forms an angle α with the workpiece surface 7 , which, as indicated in FIG. 2, is preferably between 0 ° and 45 °. The workpiece surface 7 is the surface of the workpiece in which the ridge 4 essentially lies. The choice of the angle α between 0 ° and 45 ° has the advantage that an irregularly thick ridge 4 or a jagged ridge 4 does not have a negative effect on the deburring result, since the laser radiation 2 in the case of a ridge section that has already been cut off or in the case of a no ridge section in front of the component.

FIG. 3a shows the workpiece according to FIG. 1 after carrying out process step (a). The burr volume was reduced by partially removing the burr 4 by a first relative movement of workpiece 1 and laser radiation 2 . In order to achieve a regular residual burr 6 , laser radiation is preferably used, the energy density of which is conditioned on the workpiece surface in such a way that a laser cutting process can be carried out with which part of the burr 4 is cut off. The regular residual ridge 6 forms a good prerequisite for carrying out the following process steps.

FIG. 3b also shows the workpiece 1 according to FIG. 1 after carrying out process step (a). In the case of FIG. 3b, however, method step (a) was carried out in such a way that the entire ridge 4 was removed. Furthermore, the workpiece edge 3 is provided with a chamfer and a throw 8 has been formed by carrying out process step (a). The workpiece edge 3 shown in FIG. 3b also has a uniform geometry and thus also offers a good prerequisite for carrying out the subsequent method steps.

Both for producing a workpiece edge 3 according to Fig. 3a and for producing a workpiece edge as shown in FIG. 3b, the laser radiation is 2, the energy density is conditioned on the workpiece surface in such a manner is that a removal method on Sublimationsbasis results.

FIG. 4 shows the workpiece 1 according to FIG. 1 after carrying out process steps (a) and (b). A predetermined workpiece edge geometry 5 was generated by a second set of relative movements of workpiece 1 and laser radiation 2 . To generate such a workpiece edge geometry 5 , both laser radiation 2 can be used, the energy density of which is conditioned on the workpiece surface in such a way that an ablation process based on sublimation results, as well as laser radiation 2 , the energy density of which is conditioned on the workpiece surface in such a way that a reactive removal process results, for example, the laser cutting process explained at the beginning. After carrying out process step (b), the workpiece edge 3 already has the predetermined workpiece edge geometry 5 , but the workpiece edge 3 still has a surface quality that can be further improved, which is shown in FIG. 4 by the irregular patterning of the workpiece edge 3 is indicated.

FIG. 5 shows the workpiece 1 according to FIG. 1 after the further method step (c), which is preferably provided, for smoothing the workpiece edge surface by a third relative movement or a third set of relative movements of workpiece 1 and laser radiation 2 . For smoothing the edge surface, the laser radiation 2 is preferably conditioned in such a way that the intensity is low. In order to irradiate the entire edge surface present after method step (b), the laser radiation 2 can be widened while the relative movement of workpiece 1 and laser radiation 2 is being carried out. However, it is also conceivable that the relative movement of workpiece 1 and laser radiation 2 takes place when method step (c) is carried out in such a way that the entire edge surface is scanned.

The method according to the invention enables by procedural steps carried out the Kombinati on various laser ablation mechanisms, namely the type that associated with the respective ablation mechanism  Problems ultimately don't negatively affect that Impact deburring result.

Claims (11)

1. A method for the deburring of a workpiece (1), wherein (2) heat is introduced into the to be deburred work piece (1) by laser radiation to a passage extending along an edge of the workpiece (3) ridge (4) at least from cut as to remove, characterized characterized that it includes the following steps:

• a) reducing the burr volume by removing at least part of the burr ( 4 ) by a first relative movement or a first set of relative movements of the workpiece ( 1 ) and laser radiation ( 2 ); and
• b) generating a predetermined workpiece edge geometry ( 5 ) by a second relative movement or a second set of relative movements of the workpiece ( 1 ) and laser radiation ( 2 ),

wherein steps (a) and (b) are carried out in succession. 2. The method according to claim 1, characterized in that after steps (a) and (b), the following further step is carried out:

• a) smoothing the edge surface by a third relative movement or a third set of relative movements of the workpiece ( 1 ) and laser radiation ( 2 ).

3. The method according to any one of the preceding claims, characterized in that the relative movement or the set of relative movements according to step (a) is carried out in such a way that the laser radiation ( 2 ) is guided parallel to the workpiece edge ( 3 ) in order to remove an irregular burr ( 4 ) to form a regular residual burr ( 6 ) by reducing the burr volume. 4. The method according to any one of claims 1 or 2, characterized in that the relative movement or the set of relative movements according to step (a) is carried out in such a way that the laser radiation ( 2 ) is guided along the workpiece edge ( 3 ) to the ridge ( 4 ) remove completely. 5. The method according to any one of the preceding claims, characterized in that reducing the burr Volume according to step (a) by laser cutting operation is carried out. 6. The method according to claim 5, characterized in that the energy density of the laser radiation ( 2 ) on the workpiece surface is conditioned during the implementation of step (a) to carry out the laser cutting process and the laser radiation ( 2 ) essentially on the ridge ( 4 ) is directed, and that the laser radiation ( 2 ) forms an angle (α) between 0 ° and 45 ° during the execution of the laser cutting process with the workpiece surface ( 7 ), in the plane of which the ridge ( 4 ) essentially lies. 7. The method according to any one of the preceding claims 1 to 4, characterized in that the energy density of the laser radiation ( 2 ) on the workpiece surface for performing step (a) is conditioned such that a sublimation-based removal process results. 8. The method according to any one of the preceding claims, characterized in that the energy density of the laser radiation ( 2 ) on the workpiece surface for performing step (b) is conditioned such that a sublimation-based removal process results. 9. The method according to any one of the preceding claims 1 to 7, characterized in that the energy density of the laser radiation ( 2 ) on the workpiece surface for performing step (b) is conditioned in such a way that a reactive removal process results. 10. The method according to any one of the preceding claims, characterized in that the laser radiation ( 2 ) for performing step (c) is expanded to irradiate the entire edge surface and / or that the real movement or the set of relative movements according to step (c) is carried out in such a way that the entire edge surface is irradiated. 11. The method according to any one of the preceding claims, characterized in that the laser radiation by a Giant pulse laser is generated, and that the energy density of the Laser radiation in process steps (a), (b) and - if carried out - (c) are different.