DE102012013778A1 - Forming tool for massive forming of metal material, has die cavity that is formed corresponding to the shape of component, whose regions with steel material, are formed with different material properties - Google Patents

Abstract

The forming tool (100) has a main portion that is made of the steel material. A die cavity (130) is formed corresponding to the shape of the component. The steel material is formed within the die cavity regions with different material properties. A specific adjustment of the resistance of the main portion is obtained to locally different stresses during massive forming of the metal material. The regions with different material properties are clearly distinguished from each other. An independent claim is included for a method of fabricating a forming tool.

Description

The invention relates to a forming tool for the massive forming of a metal material, which is formed from a steel material and has at least one engraving corresponding to the shape of the to be manufactured by massive forming component or workpiece.

The invention also relates to two methods for producing such molds.

Molds of the type in question are used for the massive forming of a metallic material. In the case of massive forming, a solid blank (initial workpiece) is formed into a component (formed workpiece), in which case, in particular, large changes in the shape of the metallic material are brought about. The massive forming may include several forming steps, which requires several forming tools. In the case of sheet metal forming, on the other hand, a flat finished rolling mill product is transformed. The methods and apparatus for solid forming are fundamentally different from the methods and apparatus for sheet metal forming.

The engraving of the molding tool is understood to mean the molding area which has a pressure-contact surface which comes into direct physical contact with the metal material to be formed during shaping or during forming.

During the forming of the solid metal material occurs in the engraving of the mold to locally different mechanical and possibly thermal stresses that lead to different damage, such as wear due to abrasion (as a result of material flow), thermal cracks, mechanical cracks, deformations and like. Molds of the type in question therefore have a very limited amount of stand.

In order to improve the tool life of molds, new tool materials (new steel alloys or, for example, steels produced by powder metallurgy) are repeatedly tried out. Furthermore, the tool surface can be nitrided or coated in the region of the engraving. In addition, tool inserts made of other materials (eg ceramic) are known. Despite these sometimes expensive measures, no appreciable improvement in stall volume can often be achieved.

The invention has the object of demonstrating economically viable options for improving the level of a mold tool of the kind concerned.

This object is achieved by an inventive mold with the features of claim 1.

With two independent claims, the solution of the problem also extends to two methods for producing a mold according to the invention.

Preferred developments and refinements emerge analogously for all subjects according to the invention both from the dependent claims and from the following explanations.

The mold according to the invention is characterized in that the steel material. the forming tool is within the engraving areas having different material properties, to thereby obtain a specific adaptation of the resistance of the mold according to the invention to locally different loads in the massive forming of the metal material.

Accordingly, the invention provides that the molding tool consists of only one steel material, this steel material having locally different material properties in the area of the engraving, in order thereby to achieve a local load adjustment of the molding tool. The areas with the different material properties are within, the engraving next to each other and not on top of each other, which is the case, for example, in nitriding or coating. In other words, the invention can be represented as follows: The mold according to the invention has locally different resistance capabilities distributed over the engraving, with regard to locally different loads during the deformation of the solid metal material (or during the forming process) and locally occurring failure modes , The forming tool according to the invention consisting of only one steel material (or of one steel mass) is provided with different material properties at certain locations in the area of the engraving, which can also be referred to as a partial property setting. Local areas of the engraving can be designed so load-adapted and thus resistant to the corresponding occurring failure mode.

This results in an application-optimized forming tool for massive forming. In the known from the prior art molds only a homogeneous compromise is received in terms of material properties, without attention to local stress differences and the resulting locally different requirements. The invention Mold has a high to very high level.

The molding tool according to the invention can be a forming tool for cold forming (at room temperature), for lukewarm forming (at about 200 ° C.), for warm forging (at about 600 ° C. to 900 ° C.), for hot forming (at about 1000 ° C.) ° C to 1250 ° C) or for thixoforming (above 1250 ° C). The temperatures given in brackets refer to the forming of a steel material. The metal material to be formed is, in particular, a steel material which typically stresses the engraving of the molding tool considerably.

The molding tool according to the invention may be a forging die and in particular a precision forging die. Preferably, it is a wobble die, and more particularly a precision wobble die for wobble forming and especially for tumble cold forming. (Methods and apparatus for wobble forming are in the DE 10 2007 035 493 A1 described.) But the mold according to the invention may also be a die for the extrusion. Such molds are especially designed for use on forming presses and thus press-bound. Precision tools of the type mentioned are characterized by the fact that hereby almost ready-to-assembly components or workpieces can be produced.

The regions with the different material properties within the engraving of the molding tool according to the invention may differ in terms of hardness and toughness (hardness and toughness typically conflict), strength and / or thermal conductivity. For example, within the engraving, relatively hard and brittle regions (eg, having good local wear resistance), relatively soft and ductile regions (eg, having good local fracture toughness), regions of higher or higher strength (i.e. for example, have good local compressive strength), regions of lesser or lesser strength, regions of good thermal conductivity (which may be advantageous, for example, in terms of local cooling), and / or regions of low thermal conductivity (which may be advantageous in terms of local temperature maintenance) are adjacent. It is also conceivable that the engraving of the molding tool according to the invention only has an area with certain material properties, which is surrounded by a region with different material properties. In view of the gradual (graded) differences in material properties, this juxtaposition of the regions may also be referred to as horizontal grading. The non-inventive superimposition of different regions (for example by nitriding or coating) can be referred to as a vertical grading.

It is preferably provided that the areas with the different material properties within the engraving are clearly delimited from each other. Thus, there are relatively abrupt transitions between the adjacent areas, whereby the individual areas are exactly geometrically limited. It is also conceivable that adjacent areas have a gradual or smooth transition. Both types of transition can be realized on a mold according to the invention.

It can be provided that the steel material (or the steel mass) of which the molding tool is or is a mixed material (made of different steel grades), wherein the areas with the different material properties within the engraving by locally different alloy compositions of the steel material in these Areas are formed.

The molding tool according to the invention is preferably a milled part made of a solid steel block (or a tool part produced in a comparable chip-removing manner), a rotating part and / or an eroding part. Likewise, the molding tool according to the invention may be produced as a casting (from a cast steel), in which case at least the engraving has been produced by material-removing machining. Possibilities for forming the different material properties within the engraving will be explained below.

Furthermore, it is preferably provided that the molding tool according to the invention is formed in one piece and thus indivisible. However, the mold according to the invention can also be designed in several parts and thus divisible. In particular, forging dies and extrusion dies are often divisible. At least one tool part of a multi-part mold can then be designed according to the invention.

It is particularly preferably provided that the engraving of the molding tool according to the invention has at least one section for forming a tooth geometry on the component or workpiece, wherein the areas for forming the tooth flanks are formed with high hardness and strength within this section, in particular such that these tooth flank forming areas a have higher hardness and strength than the other areas or as the remaining area of the engraving. This is done by adjusting the area achieved different material properties of the steel material from which the mold is formed. In particular, this involves a forging die or precision forging die or a swash die or precision swage die. The component to be produced is in particular a bevel gear. Such a mold will be explained in more detail with reference to the drawing.

• – Herstellen bzw. Erzeugen eines hinsichtlich der Materialeigenschaften homogenen Werkzeugkörpers mit (wenigstens) einer daran ausgebildeten Gravur durch Gießen, Fräsen, Drehen und/oder Erodieren (z. B. ECM oder EDM) eines Stahlmaterials; und
• – Erzeugen bzw. Herstellen von Bereichen mit unterschiedlichen Materialeigenschaften innerhalb der Gravur durch partielles Wärmebehandeln und/oder partielles Kaltverfestigen des Stahlmaterials.

A first method according to the invention for producing a molding tool according to the invention comprises at least the following production steps:

• Producing or producing a tool body which is homogeneous with respect to the material properties and having at least one engraving formed thereon by casting, milling, turning and / or eroding (eg ECM or EDM) a steel material; and
• Producing or producing areas with different material properties within the engraving by partial heat treatment and / or partial work hardening of the steel material.

In the course of the partial heat treatment, a partial or local heating of the mold, for example, in an oven, with an induction heating device, with a laser beam and / or a gas burner. Depending on which material properties, based on the given material properties, are to be adjusted in a heat-treated area, the heated area can be cooled slowly or rapidly. In that the respective areas are heat-treated differently within the engraving of the molding tool according to the invention, different material properties in the individual areas can be specifically set or brought about.

A partial or local work hardening of the steel material within the engraving can, for example, be brought about by targeted bombardment of the engraving with steel balls, by local stamping or the like.

• – Bereitstellen eines massiven Stahlblocks, dessen Stahlmaterial im Hinblick auf das herzustellende Formwerkzeug bereits inhomogene Materialeigenschaften aufweist;
• – Erzeugen bzw. Herstellen des Werkzeugkörpers mit (wenigstens) einer daran ausgebildeten Gravur, durch Fräsen bzw. durch Fräsbearbeitung (oder dergleichen), Drehen und/oder Erodieren des bereitgestellten Stahlblocks, wobei innerhalb der Gravur (aufgrund der inhomogenen Materialeigenschaften) bereits Bereiche mit unterschiedlichen Materialeigenschaften herausgebildet werden; und
• – gegebenenfalls ergänzendes Überarbeiten der Gravur durch partielles Wärmebehandeln und/oder partielles Kaltverfestigen des Stahlmaterials (wie obenstehend erläutert).

A second method according to the invention for producing a molding tool according to the invention comprises at least the following production steps:

• - Providing a solid steel block whose steel material already has inhomogeneous material properties with regard to the mold to be produced;
• Producing or producing the tool body with (at least) an engraving formed thereon, by milling or by milling (or the like), turning and / or eroding the provided steel block, within the engraving (due to the inhomogeneous material properties) already areas with different Material properties are formed; and
• - If necessary, additional revision of the engraving by partial heat treatment and / or partial work hardening of the steel material (as explained above).

The provided solid steel block, whose steel material has inhomogeneous material properties, can for example be previously produced or produced by a multicomponent casting with different steel grades.

In the first method according to the invention, the different material properties within the engraving are set by changing initially homogeneous material properties. Ie. Partial property settings provide the required local properties within the engraving. In the second method according to the invention, inhomogeneous material properties are already present in the starting material which, due to their local distribution, largely anticipate the later different material properties in the area of the engraving. With both proposed methods, molds according to the invention can be produced relatively inexpensively. The methods according to the invention may comprise further steps, substeps and / or intermediate steps which are not explained in more detail herein.

The invention will now be described in more detail by way of non-limiting example with reference to the drawing. The features shown in the drawing and / or explained below may, regardless of specific feature combinations, be general features of the invention. In the drawing shows the

1 a gearing in a perspective top view.

At the gearing die 100 it can be a precision forging die or a precision swage die (precision die for wobble forming). The plate-like toothing die 100 can be installed via a tool holder table or ram side in a suitable forming press. The forging or Taumelumformvorgang done in a manner known per se with a punch or a corresponding molding die.

The cylindrical tool body or tool body 110 has a top 111 and a bottom 112 on. At the top 111 is the gearing die 100 with an engraving 130 educated. The engraving 130 is regarding the top 111 arranged in the middle. The surface or pressure contact surface of the engraving 130 is with 131 designated. With 120 is one from the bottom 112 here in the engraving 130 in extending central ejector opening referred to. The gearing die 100 is integrally formed of a steel material.

The gearing die 100 serves to produce a substantially ready-to-bevel bevel gear, which is installed in particular in motor vehicle transmissions, from a solid steel material. According to the shape of the bevel gear to be produced or to be produced by deformation, the engraving has 130 a negative form of the bevel gear, wherein the engraving 130 also an annular in plan view section 132 for forming the tooth geometry on the bevel gear.

During the forming of the massive metal material or during the forming process (or forming process), the engraving takes place 130 to locally different loads, these loads depending on the type of load and the place where this occurrence to abrasion on the pressure-contact surface 131 and / or thermal or mechanical cracks in the pressure contact surface 131 to lead. This damage usually occurs only over time as the production unit progresses. From a certain degree of damage is a replacement of the Verzahnungsgesenks 100 required against a new gearing, which costs money.

To such locally different damage within the engraving 130 To avoid is inventively provided that the steel material from the toothing die 100 is formed within the engraving 130 Having areas with different material properties, thereby a specific adjustment of the resistance of the Verzahnungsgesenks 100 to get the locally different loads during the forming of the massive metal material. This concerns according to the invention only the engraving 130 with the tool function surface or pressure contact surface 131 , The tool surfaces (such as the top 111 outside the engraving 130 ) according to the invention have no regionally different material properties.

For the gearing die 100 this means concretely in the tumbling cold forming that, on the one hand, within the section 132 for the formation of the tooth geometry all areas 135 are designed to form the tooth flanks with high hardness and strength, thereby reducing the wear resistance on the pressure-contact surface 131 increase locally and reduce abrasion. Furthermore, the compressive strength and the fatigue strength are improved in these critical engraving areas. On the other hand, within the section 132 for the formation of the tooth geometry all areas 137 formed to form the axial tooth ends on the smaller circumference of the bevel gear with lower hardness and strength, thereby improving the fracture toughness in these critical engraving areas.

The gearing die 100 can be prepared as described above.

Other forming tools for the massive forming of a metal material can have areas with different material properties within their engraving, so that there is an application-optimized molding tool. In particular, this may be a gear tool for producing a toothing on a shaft, similar to that in the 1 shown toothing tool or toothing die 100 can be trained.

LIST OF REFERENCE NUMBERS

100

Verzahnungsgesenk

110

tool body

111

top

112

bottom

120

ejector opening

130

engraving

131

Pressure contact surface

132

Teeth forming section

135

Tooth flank forming area

137

Teething forming area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007035493 A1 [0015]

Claims (10)

Molding tool ( 100 ) for the massive forming of a metal material, wherein the mold is formed from a steel material and an engraving ( 130 ) according to the shape of the component to be produced by massive forming, characterized in that the steel material from which the mold ( 100 ) is formed within the engraving ( 130 ) Has regions with different material properties to thereby make a specific adaptation of the resistance of the mold ( 100 ) to obtain locally different loads during the massive deformation of the metal material. Molding tool ( 100 ) according to claim 1, characterized in that differ the areas with different material properties in terms of hardness and toughness, strength and / or thermal conductivity. Molding tool ( 100 ) according to claim 1 or 2, characterized in that the areas with the different material properties are clearly delimited from each other. Molding tool ( 100 ) according to one of the preceding claims, characterized in that the steel material from which the mold ( 100 ) is a mixed material, wherein the regions with the different material properties are formed by locally different alloy compositions. Molding tool ( 100 ) according to one of the preceding claims, characterized in that this is a milled part made of a solid steel block, turned part and / or Erodierteil. Molding tool ( 100 ) according to one of the preceding claims, characterized in that this is formed in one piece. Molding tool ( 100 ) according to one of the preceding claims, characterized in that the engraving ( 130 ) at least one section ( 132 ) to form a gearing geometry, whereby within this section ( 132 ) the areas ( 135 ) are formed for forming the tooth flanks with high hardness and strength. Method for producing a molding tool ( 100 ) according to one of the preceding claims 1 to 7, comprising the following steps: - producing a tool body which is homogeneous with respect to the material properties ( 110 ) with an engraving formed thereon ( 130 ) by casting, milling, turning and / or eroding a steel material; and - creating areas with different material properties within the engraving ( 130 ) by partial heat treatment and / or partial strain hardening of the steel material. Method for producing a molding tool ( 100 ) according to one of the preceding claims 1 to 7, comprising the following steps: - providing a solid steel block whose steel material with respect to the mold to be produced ( 100 ) already exhibits inhomogeneous material properties; and - generating the tool body ( 110 ) with an engraving formed thereon ( 130 ) by milling, turning and / or eroding the steel block. A method according to claim 9, characterized in that the solid steel block whose steel material has inhomogeneous material properties, is previously produced by a multi-component casting with different steel grades.

Images