DE102019002258A1 - Method of manufacturing a molding tool with a 3D printer - Google Patents

Abstract

A method for producing a molding tool (1), comprising at least the following steps: a) providing a 3D printer (2) and b) printing a molding tool body (3) with the 3D printer (2), wherein when printing the molding tool body (3) at least one heat pipe (4) is formed.

Description

The present invention relates to a method for producing a molding tool. Such molding tools can be used in particular as a casting mold when casting workpieces.

When casting workpieces, a liquid melt of a material such as metal or plastic is regularly poured into the casting mold or (under high pressure) injected. The casting mold can consist of one or more molds and has at least one cavity for the liquid melt. The liquid melt solidifies in the cavity and takes on an inner contour of the cavity as an outer shape. In order to achieve high productivity in casting, molds can be cooled, so that a cooling time for the workpieces is reduced. For this purpose, cooling channels, for example, can be formed in the molds, through which a working medium, such as water, flows during casting. In order to improve the cooling of the workpieces and the molding tools, it has also already been proposed to introduce heat pipes into molding tools. Using the heat of vaporization of a working medium, heat pipes allow a high heat flux density so that large amounts of heat can be transported away from the workpieces and molds. Nevertheless, the productivity of casting processes, especially for the mass production of workpieces, is not sufficient.

The object of the invention is therefore to at least partially solve the problems described with reference to the prior art and, in particular, to specify a method for producing a molding tool by means of which the productivity of casting processes can be further increased.

This object is achieved with a method according to the features of the independent patent claim. Further advantageous refinements of the invention are specified in the dependent claims. It should be pointed out that the features listed individually in the dependent claims can be combined with one another in any technologically sensible manner and define further embodiments of the invention. In addition, the features specified individually in the patent claims are specified and explained in more detail in the description, with further preferred embodiments of the invention being presented.

1. a) Bereitstellen eines 3D-Druckers und
2. b) Herstellen eines Formwerkzeugkörpers mit einem 3D-Drucker, wobei beim Herstellen des Formwerkzeugkörpers zumindest ein Wärmerohr ausgebildet wird.

A method for producing a molding tool, which has at least the following steps, contributes to this:

1. a) Providing a 3D printer and
2. b) Production of a mold body with a 3D printer, wherein at least one heat pipe is formed during production of the mold body.

The method is used to produce a molding tool that comprises a molding tool body. The molding tool is used in particular as a casting mold, part of a casting mold, injection molding tool or casting core for casting workpieces. The molding tool is in particular a permanent mold that can be used several times. However, the molding tool can also be a so-called lost shape that is destroyed when the workpiece is cast or when the workpiece is molded. In particular, the molding tool can be used as an injection molding tool for plastic injection molding. For this purpose, the molding tool can be connected in particular to an injection molding machine. Furthermore, the molding tool can have at least one inlet for a liquid melt of a material, such as metal or plastic, for example. In addition, the mold can have at least one (hollow) casting chamber into which the liquid melt can be poured or (with high pressure) injected. For this purpose, the at least one inlet for the liquid melt can open into the at least one casting chamber. The at least one casting chamber is in particular at least partially delimited by a working surface of the molding tool body. After casting, the liquid melt solidifies in the casting chamber and at least partially assumes the shape of a surface contour of the working surface of the molding tool body.

To produce the molding tool, a 3D printer is first provided in step a). A 3D printer is, in particular, a device for additive manufacturing. In additive manufacturing, the material used to manufacture a three-dimensional (3D) object is applied layer by layer in particular. The layer-by-layer structure of the three-dimensional object to be manufactured can be computer-controlled from one or more liquid or solid materials. The shape or geometry of the three-dimensional object to be manufactured can be predetermined, for example, by CAD data. Plastics, synthetic resins, ceramics and / or metals can be used as materials for 3D printing. Metal, such as steel, copper or a copper alloy, is preferred for the production of the mold.

In a step b), the molding tool body of the molding tool is produced or printed with the 3D printer. During the production or printing of the mold body, at least one (possibly not yet provided with coolant or not yet completely closed) heat pipe formed. This means in particular that the geometric structure of the at least one heat pipe is (at least partially) printed directly into the mold body during the production of the mold body. The at least one heat pipe is a heat exchanger which, using the heat of vaporization of a working medium, allows a high heat flow density. In this way, large amounts of heat can be transported through the at least one heat pipe. The at least one heat pipe is designed in particular in the manner of a so-called “heat pipe”. The at least one heat pipe comprises, in particular, an evaporation zone in which, during the casting of workpieces, the coolant of the at least one heat pipe evaporates when it reaches its boiling point. The temperature of the mold body does not rise any further because the energy supplied is converted into heat of vaporization. The evaporation of the working medium increases the pressure in the evaporation zone, so that the evaporated working medium is distributed over an entire volume of the heat pipe. The at least one heat pipe can have a cooling zone in which the temperature of the working medium can fall below the boiling point of the working medium. For this purpose, the at least one heat pipe can emit the heat, in particular to an environment. Furthermore, the at least one heat pipe can be connected or connected in its cooling zone, for example, to a heat sink or condenser. The evaporated working medium condenses in the cooling zone and releases the absorbed thermal energy as condensation heat. The liquid working medium can then be returned to the evaporation zone by capillary forces. The working medium is selected depending on the working temperature or the working temperature range of the molding tool. The working temperature of the molding tool is in particular the temperature or the temperature range to which the molding tool heats up when casting workpieces. The working medium has, in particular, a boiling point which is within the range of the working temperature of the mold. The working medium can in particular be a fluid (at working temperature). In particular, the working medium is water, mercury, potassium and / or sodium.

The geometric structures of the at least one (capillary) heat pipe that are produced by the 3D printer in step b) are in particular at least one (integrated) steam channel and at least one (integrated) condensate channel. The at least one steam channel and the at least one condensate channel can in particular be designed together or combined. In other words, this can mean that the at least one steam channel and the at least one condensate channel are “one”. The at least one steam channel is in particular at least one channel through which the evaporated working medium can flow from the evaporation zone to the cooling zone. The at least one condensate channel is in particular at least one channel through which the condensed working medium can flow from the cooling zone back to the evaporation zone. When producing the molding tool body in step b), a single heat pipe, a plurality of heat pipes or a plurality of heat pipes can be formed.

The at least one heat pipe is formed in particular in the area of the working surface of the molding tool body. Furthermore, the at least one heat pipe, the plurality of heat pipes or the plurality of heat pipes can be formed (only) in a partial area of the working surface of the molding tool body, for example in order to exclude certain areas of the working surface from cooling. For example, the area of the at least one inlet for the melt can be excluded from the formation of heat pipes. Furthermore, the at least one heat pipe is formed as close as possible to the working surface of the molding tool body. Due to the formation of the at least one heat pipe when the molding tool body is produced by the 3D printer, the at least one heat pipe is not a separate component. Instead, the at least one heat pipe is, in particular, made of the same material as the rest of the mold body and / or cohesively with the mold body. This increases the heat transfer from the cast workpiece via the molding tool body to the at least one heat pipe, so that the cooling time of the workpieces is accelerated. Due to the accelerated cooling of the workpieces, the cycle times for casting or plastic injection molding can be reduced, so that productivity increases. Furthermore, targeted cooling can reduce wear on the work surface and thus increase the service life of the mold. In addition, through targeted cooling, local material characteristics can be set in the workpiece produced. Furthermore, workpieces of the same quality can be produced over a longer period of time.

It is obvious that step b) can be carried out several times in succession if step a) has been carried out once.

The at least one heat pipe can at least partially be configured with a non-straight course. That at least one heat pipe can in particular run through areas in which a particularly high heat input is to be expected. The not straight course is particularly easy to produce with the 3D printer.

The at least one heat pipe can be designed such that it at least partially follows a surface contour of a working surface of the molding tool body. The at least one heat pipe can in particular be designed in such a way that an evaporation zone of the at least one heat pipe is at least partially (essentially) at the same distance from the work surface.

The at least one heat pipe can be designed in such a way that it extends at least partially at a distance from a working surface of the molding tool body of less than 5 mm (millimeters). The distance is preferably less than 3 mm, preferably 1 mm.

An open-pored structure can at least partially be formed between the at least one heat pipe and a working surface of the molding tool body. The open-pore structure can be, for example, a region of the molding tool body that is porous. The working medium can enter the open-pored structure from the heat pipe and evaporate there.

After step b) the at least one heat pipe can be at least partially filled with a working medium in a step c). This can mean that the at least one heat pipe is not completely closed in step B).

After step c), the at least one heat pipe can be closed in a step d). The at least one heat pipe can be closed by the 3D printer or manually, for example by a welding process.

The at least one heat pipe can have at least one capillary structure. The at least one capillary structure comprises at least one channel, preferably a plurality of channels. A diameter of the channels is dimensioned such that the working medium can be guided from the cooling zone to the evaporation zone as a result of capillary forces. The at least one capillary structure is, in particular, at least one condensate channel through which the condensed working medium flows from the cooling zone to the evaporation zone. The at least one capillary structure can completely surround a hollow area or a steam channel of the at least one heat pipe or (only) be formed between the hollow area or the steam channel and the work surface.

A cooling medium of the at least one heat pipe can be conducted through the at least one capillary structure to an evaporation zone of the at least one heat pipe.

The at least one heat pipe can be formed from the same material as the molding tool body.

It is particularly preferred to use a molding tool, produced according to one of the methods described here, for producing a sanitary article, such as in particular the housing of a fitting.

• 1: die Herstellung eines Formwerkzeugs mit einem 3D-Drucker; und
• 2: ein Teilbereich eines Formwerkzeugkörpers des Formwerkzeugs in einer vergrößerten Darstellung.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be pointed out that the figures show a particularly preferred embodiment variant of the invention, but this is not limited thereto. The same components are provided with the same reference symbols in the figures. It shows by way of example and schematically:

• 1 : the production of a molding tool with a 3D printer; and
• 2 : a partial area of a molding tool body of the molding tool in an enlarged view.

The 1 shows a molding tool 1 in the manner of an injection molding tool for an injection molding machine not shown here. The molding tool 1 includes a mold body 3 , which is shown here in longitudinal section. The mold body 3 was made by a 3D printer 2 on a printing surface 11 Printed from metal and has a casting chamber 12 on that with another mold body 3 or a lid can be closed. In the closed state of the casting chamber 12 is by the injection molding machine for the production of a workpiece (not shown here) molten plastic into the casting chamber 12 pourable or sprayable under pressure. The casting chamber 12 is through a work surface 6th of the mold body 3 limited. The work surface 6th has a surface contour 5 through which a shape of the workpiece to be produced is at least partially specified. When printing the mold body 3 with the 3D printer 2 was in the mold body 3 a heat pipe 4th educated. The heat pipe 4th has an evaporation zone 9 on where the heat pipe 4th the surface contour 5 the work surface 6th of the mold body 3 at a distance 7th follows, which is less than 5 mm in the variant shown here. Due to the non-straight course of the surface contour 5 also has the heat pipe 4th a not straight course. The heat pipe 4th extends from the evaporation zone 9 up to a cooling zone 10 . The evaporation zone 9 is at a first longitudinal end 13 of the heat pipe 4th and the cooling zone 10 at an opposite second longitudinal end 14th of the heat pipe 4th educated. One in the heat pipe 4th the working medium is in the evaporation zone 9 vaporizable during the manufacture of a workpiece. After the working medium has evaporated, the vaporous working medium can be removed from the evaporation zone 9 to the cooling zone 10 flow where it can be cooled and condensed. In the area of the cooling zone 10 is the heat pipe 4th in the variant shown here with a heat sink 15th connected. Thus one is attached to the heat pipe 4th through the workpiece during injection molding and / or during subsequent cooling to the mold body 3 heat given off by the vaporous working medium to the cooling zone 10 transportable where the heat to an environment 16 is deliverable. Because the heat pipe 4th with a very short distance to the work surface 6th is formed, the workpiece can be cooled particularly quickly. This increases the productivity of the manufacturing process for the workpieces.

The 2 shows an enlarged illustration of one in FIG 1 area shown 17th of the mold body 3 . Here, in particular, the one indicated by the 1 3D printer shown 2 printed structure of the heat pipe 4th . The heat pipe 4th comprises in the embodiment variant shown here (in its interior) a hollow area 19th or a steam duct that runs along the heat pipe 4th of the in the 1 shown evaporation zone 9 up to the cooling zone 10 extends. The hollow area 19th is (at least in part) of a capillary structure 8th or surrounded by at least one condensate channel, which also differs from that in the 1 shown evaporation zone 9 up to the cooling zone 10 extends. In the evaporation zone 9 was when printing the mold body 3 between the heat pipe 4th and the work surface 6th of the mold body 3 also an open-pored structure 18th printed. The open-pored structure 18th extends (immediately) from the heat pipe 4th to the work surface 6th . The open-pored structure 18th ends before reaching the work surface 6th (for example with a distance of less than 3 mm), so that no working medium from the heat pipe 4th can escape. After printing the heat pipe 4th and the open-pored structure 18th became the heat pipe 4th partially filled with the working medium and then hermetically sealed. The working medium can be from the heat pipe 4th into the open-pored structure 18th occur and is heated there during the casting of workpieces. The heat input through the cast workpiece increases the temperature of the mold body 3 and the working medium until the boiling point of the working medium is reached. When the boiling point is reached, the working medium begins in the open-pored structure 18th and / or the evaporation zone 9 of the heat pipe 4th to evaporate. However, the temperature does not rise any further because the heat energy supplied is converted into heat of vaporization. When the working medium evaporates, the working surface becomes 6th heat energy is thus withdrawn due to the enthalpy of vaporization of the working medium. The evaporation of the working medium increases the pressure in the evaporation zone 9 so that the vaporous working medium through the hollow area 19th to the one in the 1 shown cooling zone 10 flows. In the refrigerator section 10 The vaporous working medium condenses and is in the liquid state through the capillary structure 8th due to capillary forces in the evaporation zone 9 returned where it evaporates again.

The present invention makes it possible to increase the productivity of casting processes.

List of reference symbols

1

Forming tool

2

3D printer

3

Mold body

4th

Heat pipe

5

Surface contour

6

Work surface

7th

distance

8th

Capillary structure

9

Evaporation zone

10

Cooling zone

11

Printing area

12th

Casting chamber

13

first longitudinal end

14th

second longitudinal end

15th

Heat sink

16

Surroundings

17th

Area

18th

open-pored structure

19th

hollow area

Claims (10)

Method for producing a molding tool (1), comprising at least the following steps: a) Providing a 3D printer (2) and b) Production of a molding tool body (3) with the 3D printer (2), at least one heat pipe (4) being formed during production of the molding tool body (3). Procedure according to Claim 1 , wherein the at least one heat pipe (4) is at least partially formed with a non-straight course. Method according to one of the preceding claims, wherein the at least one heat pipe (4) is designed such that it at least partially follows a surface contour (5) of a work surface (6) of the molding tool body (3). Method according to one of the preceding claims, wherein the at least one heat pipe (4) is designed in such a way that it extends at least partially at a distance (7) from a working surface (6) of the molding tool body (3) of less than 5 mm. Method according to one of the preceding claims, wherein between the at least one heat pipe (4) and a work surface (6) of the molding tool body (3) an open-pored structure (18) is at least partially formed. Method according to one of the preceding claims, wherein after step b) in a step c) the at least one heat pipe (4) is at least partially filled with a working medium. Procedure according to Claim 6 , wherein after step c) in a step d) the at least one heat pipe (4) is closed. Method according to one of the preceding claims, wherein the at least one heat pipe (4) has at least one capillary structure (8). Procedure according to Claim 8 wherein a working medium of the at least one heat pipe (4) can be conducted through the at least one capillary structure (8) to an evaporation zone (9) of the at least one heat pipe (4). Method according to one of the preceding claims, wherein the at least one heat pipe (4) is formed from the same material as the molding tool body (3).

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