Method for producing a metallic workpiece with at least one cavity

0001The invention relates to a method for producing a metal component with at least one recess, wherein the recess is exposed by the method very economically and efficiently.

0002Workpieces with recesses, such as cavities, recesses, undercuts, cavities and the like can be produced not only by machining processes, but also by regenerative processes. When using a regenerative process, the area of ​​the workpiece, which is to represent the recess later after completion of the workpiece, provided with a support material, also called support structure, which at least partially fills the future recess during the construction of the workpiece. After completion of the construction of the workpiece, the carrier material is removed. To teach for example<patcit id="pcit0001" dnum="WO2008125352A1"><text>WO 2008/125352 A1</text></patcit> and <patcit id="pcit0002" dnum="DE19716524A1"><text>DE 19716524 A1</text></patcit>in that the carrier material can be removed from the recess. In these methods, an aqueous medium, for example, having an acidic pH can be used. However, such methods for exposing a recess are complicated in terms of space requirements and the reaction time. Also, the workpieces must not enter into any reaction with the medium to be used. Disadvantages here are in particular acidic media, which can cause corrosion of the metallic workpieces.

0003It is therefore an object of the invention to provide a method for producing a metal component with at least one recess, which can be performed easily, without high technical complexity, with high efficiency, without the metal component takes damage.

0004The solution of this object is achieved by the features of the independent claim. The dependent claims have advantageous embodiments and further developments of the invention to the content.

0005Thus, a method is provided for producing a metal component having at least one recess, comprising the following steps: First, a metal component is introduced into a heating device. The metal component can be produced in a conventional manner, for example by an injection molding process, such as, for example, cold gas spraying, and comprises at least one carrier material which at least partially fills a recess. For the purposes of the present invention, a recess means any type of cavity, ie cavities, recesses, undercuts, channels and the like, which are intentionally provided in the metal component. Not included here are pores of the metal component itself. The recess provided in the metal component may, after completion of the metal component, be, for example, a cooling channel, that is generally a channel leading to a medium, and for example for transporting Reaktionsedukten, reaction products, cooling media, including gases and liquids, or other media, such as hydraulic oils and the like may be provided. The recess may be formed in the metal component in a conventional manner. Furthermore, it is also possible to provide a plurality of recesses which are of similar design or of different shape, arrangement and dimensioning. The recess is at least partially, preferably completely, filled with a carrier material, which preserves the spatial structure of the recess during the process for producing the metal component.

0006In this case, any heating device which is set up to receive the metal component together with the carrier material and bring it to a temperature which is suitable for at least partially converting the carrier material into the gaseous state can be used as heating device. Particularly suitable here is a controllable oven.

0007In a step subsequent to the introduction or introduction of the metal component together with the carrier material into the heating device, at least one part of the carrier material is removed, exposing at least one area of ​​the recess. According to the invention, at least part of the carrier material is converted into the gas phase and condensed again in a condensation region whose temperature corresponds to or lies below the solidus temperature of the carrier material. This procedure can be represented by the following reaction equations (reaction equilibria), wherein a first reaction equilibrium is given by a and a second reaction equilibrium by b:<chemistry id="chem0001" num="0001"><img file="EP3552756A1_D0001.tif" /></chemistry>

0008From this it can be seen that the carrier material, in short "M", is in an equilibrium, namely between its solid form, "M_s"and its gaseous form" M_G"The first reaction equilibrium a between M_s and M_G is present in a warm region of the heater, so that the carrier material at least partially passes from its solid state to the gaseous state. This can be done by simple evaporation to form a liquid intermediate phase, or by sublimation of the carrier material. A sublimation reaction is particularly advantageous since it avoids a liquid phase which is usually more voluminous and which could lead to damage in the surrounding metal component.

0009As soon as the carrier material is in the gaseous state, it is distributed by diffusion in the heating device. It is thus removed from the recess, whereby the recess is at least partially exposed. By subsequent condensation of the gaseous carrier material by the second reaction equilibrium b, the product, namely M, is the first reaction equilibrium_G, deprived, leaving the balance on the side of M_G is moved. It is thus transferred further carrier material in the gas phase to restore the first reaction equilibrium, which is further removed by condensation carrier material.

0010The second reaction, ie the condensation of the gaseous carrier material, which is also present as an equilibrium reaction, takes place by condensing the gaseous carrier material in a condensation region. The condensation region has a temperature which corresponds to or lies below the solidus temperature of the carrier material. The lower the temperature of the condensation zone, the faster the condensation reaction takes place and the faster and more efficient the second reaction equilibrium gaseous carrier material is removed again in the solid state, which in turn removes further gaseous carrier material from the recess (first reaction equilibrium) accelerates and entertains.

0011Thus, gradually without the addition of chemicals and thus in a very less expensive, safe, economical and efficient way carrier material is removed from the recess and the recess thus at least partially exposed.

0012These reactions of transferring the carrier material into the gas phase and condensing the gaseous carrier material in a condensation region, which is outside the metal component, can be carried out until the recess is completely exposed. For a temporal streamlining of the method, however, it is advantageous that only a part of the carrier material is removed from the recess by the process shown above, and residual constituents are removed on carrier material, for example by rinsing or blowing.

0013The metal component is preferably designed as a steel component, since this gives the metal component very good mechanical properties.

0014According to an advantageous development of the condensation region is outside the heater. This has the advantage that the recondensed carrier material is removed directly from the heater and thus both the arrangement of the heater and the process management are easy and easy to handle.

0015According to an alternative development of the condensation region is within the heater. This is possible, for example, by using a two-zone furnace. As a result, the heater can be made more compact and thus space-saving.

0016Since most metal components are subjected to a heat treatment to improve the structure, the surface and / or the mechanical properties, the method can advantageously be streamlined by transferring at least a portion of the support material into the gas phase at a temperature which simultaneously Refinement of the metal component causes. The finishing can be carried out at different temperatures depending on the metal or alloy used for the metal component. Suitable finishing steps are, for example, hardening, solution heat treatment, tempering or sintering of the metal component. The appropriate temperature can be found by simple experiments. Through this procedure, the metal component is annealed during the removal of the carrier material or refined, which saves time and costs for the process.

0017Further advantageously, the method comprises a step of applying a negative pressure to the heating device. The negative pressure removes the gaseous carrier material more quickly from the reaction equilibrium. In addition, the applied negative pressure acts as an insulator and reduces the heat loss through the condensation region, which is particularly advantageous if the condensation region lies in the heating device.

0018Alternatively or additionally, the method for faster removal of gaseous carrier material may include a step of supplying a gas into the heater. As a result, the gaseous carrier material is virtually expelled from the recess. In addition, the gas space is filled with additionally supplied gas, so that the removal of gaseous carrier material is promoted by increased convection.

0019The gas supplied is in particular an inert gas, such as nitrogen or helium, ie a gas which does not react with either the carrier material or the metal at the temperature prevailing in the heating device. However, the supplied gas can also be a forming gas, reaction gas or a mixture of the abovementioned gases. By suitable choice of the gas, the expulsion of the gaseous carrier material can be significantly accelerated, so that the recess is exposed within a short time.

0020According to a further advantageous development, it is provided that the condensation of the gaseous carrier material takes place on a cold finger. Cooling fingers are space-saving devices which can be arranged inside or outside the heating device and constitute a condensation region for the gaseous carrier material. They are inexpensive and flexible to arrange. Also, their temperature and thus the condensation rate of gaseous carrier material is very easy to control.

0021According to an alternative embodiment, the condensation of the gaseous carrier material takes place in a cold trap. The cold trap is usually located outside the heater. It offers the advantage that the recondensed carrier material can be collected very easily locally and the amount of re-solidified carrier material forming is easily traceable. This embodiment is particularly suitable for simultaneous application of negative pressure or for supplying a gas for expelling the gaseous carrier material.

0022Further advantageously, the cold trap is connected upstream of a vacuum pump, since thereby a better deposition of the gaseous carrier material can be ensured.

0023To improve the removal of the carrier material, it is furthermore advantageously provided that the cold trap is connected downstream of a gas flow emerging from the heating device.

0024The carrier material is preferably a metallic carrier material, since metallic carrier materials can pass very easily controllably into the gas phase at relatively low temperatures and can be recondensed in a controlled manner. The metallic carrier material is in particular selected from: magnesium, aluminum, zinc, antimony, mixtures or alloys thereof. These materials are available at moderate prices and easy to process. Alternatively or additionally, the carrier material may contain a ceramic carrier material. This serves in particular when used in combination with a metallic support material of the enforcement of the structure. Once a part of the metallic carrier material is removed, the residual structure can be removed very easily by mechanical action, for example by blowing or rinsing completely exposing the recess.

0025Further details, advantages and features of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawing. It shows:<ul id="ul0001" list-style="none"><li><figref idref="f0001">Fig. 1</figref> a diagram illustrating method steps for producing a metal component with a recess according to an embodiment,</li><li><figref idref="f0001">Fig. 2</figref> a schematic view of an apparatus for performing the method according to a first embodiment and</li><li><figref idref="f0002">Fig. 3</figref> a schematic view of an apparatus for performing the method according to a second embodiment.</li></ul>

0026In the figures, only the essential features of the invention are shown. All other features are omitted for clarity. Furthermore, like reference numerals number like components or components.

0027In detail shows <figref idref="f0001">FIG. 1</figref> schematized method steps of a method for producing a metal component with at least one recess. The metal component may advantageously be formed as a steel component.

0028In a first method step 100, the metal component is introduced into a heating device. The metal component comprises at least one recess which is at least partially filled with a carrier material. The recess may be, for example, a recess, a cavity, a cavity, an undercut or the like, which serves as a medium-conducting channel in the finished metal component, for example.

0029The heating device is designed in particular as a furnace and serves to bring the metal component together with the carrier material to a designated temperature.

0030Following the introduction of the metal component into the heating device, a removal 200 of at least one part of the carrier material takes place, exposing at least one region of the recess.

0031For this purpose, at least a part of the carrier material is transferred into the gas phase, for example by sublimation or by passing through a liquid phase. By transferring carrier material into the gas phase, carrier material is removed from the recess. It is distributed by diffusion in the surrounding space.

0032The gaseous carrier material is condensed in a condensation region. The condensation region may be within the heater or outside the heater and has a temperature equal to or less than the solidus temperature of the carrier. Thus, the carrier material is recondensed in this relatively cool condensation region and is thereby removed from the reaction equilibrium between solid carrier material in the tempered region of the heating device and gaseous carrier material also in the tempered region of the heating device. This shifts the above-mentioned equilibrium and further solid carrier material is transferred from the recess into the gas phase which recombines outside the metal component, for example in a cold trap or on a cold finger. The respective Temperauren for transferring the carrier material in the gas phase and also for condensing the same, can be easily found by experimental experiments, or be taken from appropriate tables.

0033By the method described above, a metal component with a recess is produced in a simple and very efficient manner, without the need for the addition of the carrier material dissolving chemicals. To accelerate the transfer of the carrier material in the gas phase, it may be advantageous to apply a negative pressure to the heater or to pass a gas through the heater, through which the gaseous carrier material is removed from the metal component particularly quickly.

0034<figref idref="f0001">FIG. 2</figref> shows a device 1 for carrying out a method for producing a metal component with at least one recess. The process can be as in<figref idref="f0001">FIG. 1</figref> set forth in the device 1 are executed.

0035The device comprises a furnace 2, in which a metal component 10 is introduced. The metal component 10 has a carrier material 11 which at least partially fills a recess. After completion of the process, the recess in the metal component is exposed and can serve, for example, as a medium-leading channel, for example for transporting a coolant, a reaction product or reaction educts.

0036To the furnace 2, a cooling line 3 is connected, which connects the furnace 2 with a cooling finger 5 via a valve 4. The cold finger 5 corresponds to a condensation region for the condensation of the gaseous carrier material.

0037In addition, a vacuum line 6 is connected to the furnace, which connects the furnace 2 via a valve 7 with a vacuum connection 8, for example a vacuum pump.

0038The furnace 2 is held at a temperature at which the carrier material 11 passes into the gas phase. It turns inside the furnace 2, a reaction equilibrium between solid substrate 11 in the recess and a gaseous carrier material. By opening the valve 4, the furnace 2 is connected to the cold finger 5. Thus, gaseous carrier material flows to the cold finger 5. The cooling finger 5 is held at a temperature which corresponds to the solidus temperature of the carrier material 11 or below. As a result, the gaseous carrier material is condensed on the cooling finger 5. Thus, the above reaction equilibrium gaseous carrier material is removed and thus from the solid, located in the recess carrier material 11, replicated. Thus, solid carrier material 11 is gradually removed from the recess in the metal component 10 via the gas phase and recondensed at the cold finger 5. The recess is depleted of carrier material 11, and is thus at least partially exposed.

0039The removal of gaseous carrier material can be accelerated by the opening of the valve 7, as a negative pressure, and in particular a vacuum, can be applied to the furnace 2.

0040The device is very well suited to produce a metal component with at least one recess. Any remnants of solid support material 11 can be completely removed from the recess, for example by using compressed air or a jet of water.

0041<figref idref="f0002">FIG. 3</figref> shows a further device 1 for producing a metal component with at least one recess according to another embodiment.

0042As a difference to the device 1 from <figref idref="f0001">FIG. 2</figref> it can be seen that the cooling line 3 comprises a cold trap 9, in which the gaseous carrier material is condensed. In this embodiment, the cold trap 9 corresponds to the condensation area for the condensation of the gaseous carrier material. The expulsion of the gaseous carrier material is facilitated by the gas line 12, after opening the valve 13, a gas, such as an inert gas, a forming gas, a reaction gas or the like, is passed through the furnace 2. Thus, the gas space in the furnace 2 is diluted with the supplied gas and it is emulated by the accelerated removal of the gaseous carrier material from the furnace 2 and condensation thereof in the cold trap 9 faster gaseous carrier material from the present in the recess of the metal component 10 solid support material 11.

0043Also in <figref idref="f0002">FIG. 3</figref> shown device 1 is suitable for that <figref idref="f0001">FIG. 1</figref> To execute illustrated method and produce a metal component with a recess within a short time without high technical complexity.

0044In addition to the above written description of the invention is to the additional disclosure hereby explicitly to the drawings of the invention in the <figref idref="f0001 f0002">Fig. 1 to 3</figref> Referenced.

LIST OF REFERENCE NUMBERS

0045<dl id="dl0001" compact="compact"><dt>1</dt><dd>contraption</dd><dt>2</dt><dd>oven</dd><dt>3</dt><dd>cooling line</dd><dt>4</dt><dd>Valve</dd><dt>5</dt><dd>cold finger</dd><dt>6</dt><dd>vacuum line</dd><dt>7</dt><dd>Valve</dd><dt>8</dt><dd>vacuum connection</dd><dt>9</dt><dd>cold trap</dd><dt>10</dt><dd>metal component</dd><dt>11</dt><dd>support material</dd><dt>12</dt><dd>gas pipe</dd><dt>13</dt><dd>Valve</dd><dt>100-200</dt><dd>steps</dd></dl>