PRODUCTION METHOD FOR A SHAPE-IMPARTING TOOL PART OF A FORMING TOOL

Abstract

A method of manufacturing a tool part of a forming tool. The method includes forming a tool element of the tool part having a shape-imparting operating face and at least one first cooling duct for cooling a liquid using an additive manufacturing machine. The first cooling duct has at least one rectifier portion including a blocking direction and an opposing passing direction. The blocking direction has a higher flow resistance to cooling liquid than the passing direction.

Claims

1. A method of manufacturing a tool part of a forming tool, the method comprising: forming a tool element of the tool part having a shape-imparting operating face and at least one first cooling duct for cooling a liquid using an additive manufacturing machine, wherein the at least one first cooling duct has at least one rectifier portion including a blocking direction and an opposing passing direction, cooling liquid flowing through the at least one first cooling duct in the blocking direction has a higher flow resistance than cooling liquid flowing through the at least one first cooling duct in the passing direction.

2. The method of claim 1, wherein the at least one rectifier portion has a primary portion and a counterflow portion, the counterflow portion branches off from the primary portion at an angle of less than 90 degrees in the blocking direction and opens into the primary portion at an angle of more than 90 degrees in the passing direction.

3. The method of claim 1, wherein the at least one rectifier portion has a primary portion and at least one rigid guiding element, the at least one rigid guiding element is inclined in the passing direction and extends toward a center of the primary portion.

4. The method of claim 1, wherein the step of forming the tool element using the additive manufacturing machine includes forming a plurality of clearances within the tool element, the plurality of clearances are spaced apart from each first cooling duct.

5. The method of claim 1, further comprising inserting the tool element into a recess of a base element of the tool part such that the at least one first cooling duct is fluidly connected to a second cooling duct formed within the base element.

6. The method of claim 5, wherein the recess is formed in the base element using subtractive machining.

7. The method of claim 5, wherein the second cooling duct is formed in the base element using subtractive machining prior to insertion of the tool element.

8. The method of claim 5, wherein the tool element in a region of the shape-imparting operating face is made from a harder material than that of the base element.

9. The method of claim 5, wherein the step of forming the tool element using the additive manufacturing machine includes forming a groove surrounding a connecting opening at an end of the first cooling duct for connecting to the second cooling duct, further comprising inserting an elastic sealing element into the groove prior to inserting the tool element into the recess.

10. The method of claim 1, wherein the tool element includes a plurality of regions, two of the plurality of regions are made of different materials.

11. A method of manufacturing a tool part of a forming tool, the method comprising: forming a tool element of the tool part having a shape-imparting operating face and at least one first cooling duct for cooling a liquid using an additive manufacturing machine; forming a base element of the tool part having a recess and a second cooling duct using subtractive machining; and inserting the tool element into the recess of the base element such that the at least one first cooling duct is fluidly connected to the second cooling duct, the second cooling duct is formed in the base element prior to inserting the tool element into the recess, wherein the at least one first cooling duct has at least one rectifier portion including a blocking direction and an opposing passing direction, cooling liquid flowing through the at least one first cooling duct in the blocking direction has a higher flow resistance than cooling liquid flowing through the at least one first cooling duct in the passing direction.

12. The method of claim 11, wherein the at least one rectifier portion has a primary portion and a counterflow portion, the counterflow portion branches off from the primary portion at an angle of less than 90 degrees in the blocking direction and opens into the primary portion at an angle of more than 90 degrees in the passing direction.

13. The method of claim 11, wherein the at least one rectifier portion has a primary portion and at least one rigid guiding element, the at least one rigid guiding element is inclined in the passing direction and extends toward a center of the primary portion.

14. The method of claim 11, wherein the step of forming the tool element using the additive manufacturing machine includes forming a plurality of clearances within the tool element, the plurality of clearances are spaced apart from each first cooling duct.

15. The method of claim 11, wherein the step of forming the tool element using the additive manufacturing machine includes forming a groove surrounding a connecting opening at an end of the first cooling duct for connecting to the second cooling duct, further comprising inserting an elastic sealing element into the groove prior to inserting the tool element into the recess.

16. A tool part of a forming tool, the tool part comprising: a tool element having a shape-imparting operating face and at least one first cooling duct for cooling a liquid, the tool element being an additive depositable material, wherein the at least one first cooling duct has at least one rectifier portion including a blocking direction and an opposing passing direction, cooling liquid flowing through the at least one first cooling duct in the blocking direction has a higher flow resistance than cooling liquid flowing through the at least one first cooling duct in the passing direction.

17. The tool part of claim 16, wherein the at least one rectifier portion has a primary portion and a counterflow portion, the counterflow portion branches off from the primary portion at an angle of less than 90 degrees in the blocking direction and opens into the primary portion at an angle of more than 90 degrees in the passing direction.

18. The tool part of claim 16, wherein the at least one rectifier portion has a primary portion and at least one rigid guiding element, the at least one rigid guiding element is inclined in the passing direction and extends toward the center of the primary portion.

19. The tool part of claim 16, further comprising a plurality of clearances formed within the tool element, the plurality of clearances are spaced apart from each first cooling duct.

20. The tool part of claim 16, further comprising: the tool element including a groove surrounding a connecting opening at an end of the first cooling duct; a base element having a recess and a second cooling duct fluidly connected to the at least one first cooling duct; and an elastic sealing element disposed in the groove and engaging the tool element and the base element.

Description

DRAWINGS

[0037] Further advantageous details and effects of the disclosure are explained in more detail hereunder by means of exemplary forms illustrated in the figures in which:

[0038] FIG. 1 shows a perspective view of parts of a tool part during a first step of a method according to a first form;

[0039] FIG. 2 shows a perspective view of the tool part from FIG. 1 during a second step of the method;

[0040] FIG. 3 shows an enlarged detailed view of FIG. 1;

[0041] FIGS. 4 and 5 show enlarged cross-sectional views of the tool part from FIG. 1;

[0042] FIG. 6 shows a perspective view of part of a tool part during a first step of a method according to a second form;

[0043] FIG. 7 shows a perspective view of parts of the tool part from FIG. 6 during a second step of the method;

[0044] FIG. 8 shows a perspective view of the tool part from FIG. 6 during a third step of the method;

[0045] FIGS. 9 to 12 show perspective views of different forms of tool elements produced according to the present disclosure; and

[0046] FIGS. 13-16 show cross-sectional views of a rectifier portion of a cooling duct of a tool part produced according to the present disclosure.

[0047] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

[0048] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0049] Identical parts are at all times provided with the same reference signs in the various figures, which is why said parts are typically also described only once.

[0050] FIG. 1 shows a perspective view of parts of a tool part 1 which can be produced by the method according to the present disclosure. The tool part 1 can form, for example, part of a female die or a male die of a press hardening tool (not illustrated). A sheet-metal part can be hot formed and hardened by means of the press hardening tool. The forming takes place inter alia on an operating face 4 of the tool part 1. FIG. 1 schematically shows an intermediate step of the production method, prior to a tool element 10 being joined to a base element 20. Both elements 10, 20 here are configured so as to be cuboid. This is however to be understood to be purely exemplary or schematic, for example.

[0051] The tool element 10 is produced from steel by additive manufacturing, for example by selective laser melting (SLM). A first cooling duct 11 which overall is configured so as to be bent and opens into two first connecting openings 12 has been generated in the course of the additive manufacturing. A surface 2 which in the finished state forms part of a shape-imparting operating face 4 of the tool part 1 is configured on a forming region 10.1 of the tool element 10. In order for the final shape of the surface 2 to be set, the latter at the end of the additive manufacturing can also be subtractively post-machined. Moreover, a hard coating, for example of tungsten carbide, could be applied.

[0052] The first cooling duct 11 in this exemplary form and in each of the exemplary forms described hereunder can have a rectifier portion 15 which will be explained in more detail with reference to FIGS. 13 to 16.

[0053] The base element 20 can be conventionally cast from tool steel, for example, and has two second cooling ducts 21 which are configured so as to be straight and may be drilled into the base element 20. The base element 20 furthermore has a cuboid recess 23 which can be molded directly when casting, for example, or else be subsequently shaped by subtractive machining such as by milling, for example. The dimensions of the recess 23 are adapted to those of the tool element 10 such that the latter can fit into the recess 23. The cooling ducts 21 open in each case into second connecting openings 22 on the periphery of the recess 23. A surface 3 of the base element 20 in the finished state likewise forms part of the shape-imparting operating face 4.

[0054] FIG. 2 shows the tool part 1 after the insertion of the tool element 10 into the recess 23 of the base element 20. The surface 2 of the tool element 10 transitions in a practically seamless manner to the surface 3 of the base element 20. The first connecting openings 12 are directly adjacent to the second connecting openings 22, as a result of which a fluidic connection between the cooling ducts 11, 21 is provided. More specifically, the two cooling ducts 21 are connected to one another by the bent first cooling duct 11, wherein the bent shape of the first cooling duct, which can be easily generated by the additive manufacturing, provides an improved flow resistance, as opposed to angled cooling ducts which can be generated by cross-drilled holes.

[0055] In order to improve a liquid-tight connection between the first cooling duct 11 and the second cooling ducts 21, sealing is provided by a rubber-elastic O-ring 30. The latter fits into an annular groove 13 which is disposed about the first connecting opening 12, as can be seen in the detailed illustration of FIG. 3. As is derived from the cross-sectional illustrations in FIGS. 4 and 5, the groove 13 has an undercut cross section and in terms of the dimensions of said groove 13 is adapted to the O-ring 30 such that the latter can first be jammed into the groove 13, as is illustrated in FIG. 4, and upon the insertion of the tool element 10 into the recess 23 is pushed into the groove 13 by the adjacent base element 20.

[0056] During a forming procedure, a sheet-metal part (for example after prior austenitizing) is formed between the tool part 1 and a further part of the press hardening tool (female die or male die). During the forming, or directly subsequently thereto, a cooling liquid (usually water, optionally with additives) is directed through the cooling ducts 11, 21 as a result of which intense cooling of the operating face 4 and thus also of the sheet-metal part takes place. The microstructure of the finished sheet-metal part is significantly influenced by this cooling. The cooling in turn can be influenced by various parameters, for example by the flow of coolant, the spacing of the cooling ducts 11, 21 from the operating face 4, and the thermal conduction within the tool element 10 and the base element 20. An individual design of the first cooling ducts 11 is possible as a result of the additive manufacturing, this having a direct influence on the microstructure in the region of the surface 2 of the tool element 10. In the example illustrated in FIGS. 1 and 2, the first cooling duct 11 runs at a constant spacing so as to be relatively close below the operating face 4. Other possibilities are however also provided, as will be illustrated hereunder.

[0057] FIGS. 6 to 8 show method steps of a second form of the method according to the present disclosure. As is illustrated in FIG. 6, a base element 20 having a single second cooling duct 21 which is routed in a straight line is initially present here. The cooling duct 21 is drilled through the base element 20 and runs at a constant spacing from the surface 3. When the cooling characteristics are to be changed in a sub-region, a recess 23 can be generated by subtractive machining; that is to say that part of the base element 20 is removed as is illustrated in FIG. 7. As a result, the second cooling duct 21 is divided and second connecting openings 22 result on the periphery of the recess 23. A tool element 10 which matches the recess 23 and has a first cooling duct 11, the first connecting openings 12 of the latter being adapted to the second connecting openings 22, is produced by additive manufacturing, the first cooling duct 11 however does not having a straight profile which continuously runs close to the surface but being bent and partially running at a large spacing from the surface 2 of the tool element 10. As is illustrated in FIG. 8, the tool element 10 is inserted into the recess 23 so that the two parts of the second cooling duct 21 are connected to one another by the first cooling duct 11. By virtue of the larger spacing from the operating face 4, the cooling effect which is locally imparted by the first cooling duct 11 in terms of quality is inferior than that imparted by the parts of the second cooling duct 21. The tool element 10 can optionally be produced from a harder material than that of the base element 20.

[0058] As an alternative to the tool element 10 illustrated in FIG. 7, other tool elements 10 can also be inserted into the recess 23. FIG. 9 in a perspective illustration shows an alternative tool element 10 having a first cooling duct 11 which likewise has a bent profile, but is disposed so as to run continuously at an almost constant spacing from the surface 2. No reduced cooling effect results in comparison to the continuous straight second cooling duct 21 which is illustrated in FIG. 6, but a cooling effect which under certain circumstances is even reinforced, because a larger face can be cooled by a single cooling duct 11. For the sake of simplicity, only one bend or a one loop of the first cooling duct 11 is illustrated in FIG. 7; in principle however, a plurality of successive loops could also be provided such that an overall meandering profile results.

[0059] The exemplary form in FIG. 10 differs from that in FIG. 9 in that the forming region 10.1 is produced from iron or steel, while a line region 10.2 which in terms of the operating face 4 lies therebehind is produced from copper or a copper alloy. The different materials can be readily combined with one another in the course of an additive manufacturing method, for example in such a manner that different metallic powders are successively applied and fused in regions. In this way, the mechanical resilience of the iron and the high thermal conductivity of the copper can be advantageously combined in one tool element 10.

[0060] The exemplary form in FIG. 11 shows a first cooling duct 11 which is helically configured and, similar to that in FIG. 10, is disposed so as to be largely close to the operating face 4. The cooling effect on the operating face 4 and the workpiece to be formed can be increased by the helical shape, in a manner similar to a meandering shape.

[0061] FIG. 12 shows another form of a tool element 10 which can have a first cooling duct (not shown) according to any of the previously mentioned exemplary forms. A lower face 5 lying opposite the operating face 4, and a plurality of clearances 14 which have been produced in the course of the additive manufacturing, can be seen in the perspective illustration of FIG. 12. In the example illustrated, said clearances 14 are configured so as to be hexagonal/prismatic and disposed in the manner of honeycombs. Material and weight can be saved as a result of the clearances 14, on the one hand; on the other hand, the thermal conductivity of the tool element 10 can be influenced in a targeted manner because said thermal conductivity is locally reduced as a result of the clearances 14.

[0062] As has already been mentioned above, the first cooling duct 11 in each of the exemplary forms shown can have a rectifier portion 15, the construction thereof being explained hereunder by means of FIGS. 13 to 16.

[0063] FIG. 13 shows a schematic cross-sectional illustration of part of the tool element 10, having a rectifier portion 15 which forms part of the first cooling duct 11. The rectifier portion 15, which is configured in the manner of a Tesla valve, here is illustrated so as to be overall elongated; however, the rectifier portion 15 could also be configured so as to be bent, for example, wherein the structure described hereunder can be maintained in a modified form. An almost straight continuous primary portion 16 as well as a plurality of counterflow portions 17, which in an alternating manner are disposed on both sides of the primary portion 16, can be identified within the rectifier portion 15. FIGS. 14 to 16 show in each case a detail from FIG. 13, having a single counterflow portion 17. The latter, when viewed in a blocking direction S, branches off from the primary portion 16 at an acute angle a and opens into the primary portion 16 again at an obtuse angle 13. The counterflow portion 17 here is delimited by a guiding element 18 which has been produced in the course of the additive manufacturing of the tool element 10, on the one hand. The guiding element 18 is disposed on the primary portion 16 and, when viewed in the blocking direction S, runs from the center of the primary portion 16 toward the outside. If cooling liquid flows in the blocking direction S through the rectifier portion 15, as is illustrated in FIG. 15, the coolant flow is split by the guiding element 18, whereby a part flows through the counterflow portion 17, as a result of which imparting a reversal of direction, and in the opposite direction finally meets the coolant flow in the primary portion 16. Substantial turbulences which render a laminar flow impossible arise here. The effect is substantially reinforced in that a plurality of counterflow portions 17 and associated guiding elements 18 are disposed in succession, as is illustrated in FIG. 13. However, if cooling liquid is directed through the rectifier portion 15 in a passing direction D, counter to the blocking direction S, a coolant flow through the substantially straight primary portion 16 is almost exclusively configured, while the flow in those counterflow portions 17 is negligible. An at least largely laminar flow can thus be configured under certain circumstances. The rectifier portion 15 in the blocking direction S thus has a substantially higher flow resistance to the cooling liquid than in the passing direction D. In the exemplary forms illustrated, the difference can correspond to a factor between 10 and 100, for example.

[0064] Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

[0065] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0066] The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.