DE102007005257A1 - Forming die or punch for hot deformation consists of at least two segments, at least one with recesses in contact surface with other - Google Patents

Abstract

The forming die or punch (15) has a suitable external outline to produce the required component. The die or punch consists of at least two segments (1, 2), at least one of which is made with recesses in its contact surface where this surface meets the contact surface of the other segment, forming channels enabling the temperature to be set by means of a temperature-adjusting coolant.

Description

The The invention relates to a molding die or molding die for hot working or form hardening of components, in particular body panels, which consists of at least two segments. The molding die or Formpatrize has an outer contour when pressing or forming molds for the component.

The The invention further relates to a method for hot forming or Mold hardening of such a component.

Around certain mechanical characteristics, such as ductility and set the strength of a metallic component targeted, this is subjected to a heat treatment, in which also hardening can be involved. High strength steels, For example, FeMn steels require their mechanical Processing at high degrees of deformation heating to temperatures typically above 900 degrees Celsius. To give you a desired To achieve strength, hardening is performed. In this form of heat treatment, the component with cooled at a high speed, either by Formation of certain microstructures such as martensite formation or the formation of Zwischenstufengefügen a certain strength is reached. Also by training segregates (precipitation hardening) or by incorporation of foreign atoms (Bohr, nitrogen, synthetic material) Such consolidation can take place in this way. When hardening can at the same time also a form-shaping or form-preserving one Operation done. In direct mold hardening, the heated component, For example, a sheet metal blank, in the form of the final contour brought and hardened by cooling. at a two-step process such as indirect form hardening The component, such as a body panel, first cold preformed (deep drawn) and then at temperatures above 900 ° Celsius brought to its final shape before it in the molding press is cooled selectively. Furthermore, it is also conceivable, a Finalize the component by cold or hot thermoforming, heat it up and then cool in the mold. In this case, the shape works when hardening as form-retaining and prevents the hardening distortion.

Form-hardening makes it possible to transform high-strength steels, such as the 22MnB5 type-borne steel, to high degrees of deep-drawing, thereby achieving strengths> 1600 Newton / cm ² for the component. Thus, crash-relevant body panels of high strength can be created with high design freedom.

At the Form hardening in mass production, in particular of body components, put high demands on quality and efficiency of the component manufacturing process. The serial production of form hardened parts is particularly economical when high cycle times of the mold hardening device can be achieved. For this one is possible effective cooling of the tool needed.

Various devices and methods for controlling the temperature of forming pressing operations are known from the prior art. That's how it shows DE 88 12 140.2 U1 a control device for thermoregulation of a mold. In this case, the coolant flows in ducts through the mold.

The DE 198 10 304 C1 describes a double belt press for the production of plate-like materials, in which the plate is made of particles with binders under heat and pressure. The required for the production of particular chipboard surface pressure is applied by strong support plates having transverse to the production line across the width of channels. The channels lie in the running direction directly to each other and are connected at the ends by elbows. Through the channels, the pressing section is heated by means of a thermal oil.

The DE 196 48 708 A1 describes a controlled cooling of a hot forming tool. For this purpose, the temperature distribution of the tool is detected by means of a thermal imaging camera. This thermal image is evaluated and the data are used to control spray nozzles, which apply a coolant to the tool and cool it down locally.

The DE 102 30 837 A1 discloses an apparatus for hot working metallic blanks. To cool the hot forming tool liquid nitrogen is injected from an upper chamber through holes in the tool holder on the tool and thereby deprives of heat.

Will, as in the DE 196 48 708 A1 and the DE 102 30 837 A1 used a coolant evaporation, so arise in large molds large amounts of steam, which causes problems in the manufacturing sector and it is associated with high costs to use frozen gases. For a temperature control by means of flowing medium, it is from the DE 88 12 140 U1 and the DE 198 10 304 C1 known to introduce straight ducts in the mold. The open ends of the conduit bores must be connected by elbows. With strong formation of the outer contour of the molding tool, which is composed of a molding die and a Formpatrize, the problem may occur that due to the straight lines due to their locally varying distance to the outside Enkontur the form insufficient cooling degrees can be achieved.

In front This object of the prior art is to provide a mold hardening tool and to provide a method of thermoforming a component, which high cycle times in the series production of such components allowed.

Farther It is the object of the invention to provide a cost-effective mold hardening tool provide.

A Another object of the invention is locally defined temperatures and cooling rates in the mold hardening tool.

The Solution to this problem is achieved by the present invention that provides the mold cavity die or the Forming hardship male from at least two segments. For this, the female or male can be made from an upper segment, which the component during curing gives the shape contour and a lower Segment, which acts as a support for the upper segment, be constructed. This has the advantage that only part of the Formhärtematrize or shape-hardening patrix, namely the upper segment, the so-called form shell, made of a high quality temperature resistant expensive tool steel must exist while in relation on the shaping functionless lower tool segment, the like called core, made of inexpensive material, such as Cast iron can be made. This core then bears supportive the upper mold shell.

The Contact surfaces of the core and / or the shell mold have recesses in channel form. By joining together of core and form steel shell creates a channel pattern through which a fluid temperature control medium is performed. As a cooling or Heating means may include, for example, water, oils, salts, or cooled gases such as nitrogen can be used.

Farther is advantageous in such a segmented device that curved channels in relation to the forming surface can be introduced into the tool. Because the shaping Outer contour of the mold hardening die or molding die is formed three-dimensional, arise at just by the Tool leading conventional cooling pipes or cooling holes depending on the distance of the cooling channel to the mold surface on these local heat differences.

There in a segmented molding die or die, the cooling channels freely dimensioned along the contact surface are, it is possible to adjust the channels accordingly to lead the outer contour, making a uniform Distance of the channels to the outer surface of the Mold surface is achieved. This will be a homogeneous Cooling effect achieved in the mold.

Vice versa But is also conceivable, locally a greater distance the channels to the outer contour to choose. This then results in a locally lower cooling effect. However, this locally varying cooling effect can also arise if the channel cross sections are changed locally, for example reduced. Preferably, the channels in the core and the shell mold placed in such a way that they intersect. When passing a Fluids then flows through this section by section Channel portions of the core and the shell mold.

The webs remaining between the channels come sealingly to lie on each other. Through the bars and other contact surfaces By means of surface pressure, the pressing force is absorbed during mold hardening.

The For example, the pattern of the channels may be serpentine or be designed as herringbone pattern. The introduction the pattern in the core and the shell shape happens for example when Pouring or by a later milling. Advantageously, the molded structures and patterns in opposite directions arranged, for example as staggered herringbone pattern in core and form shell.

In In another embodiment, a channel pattern may be formed thereby be that ridge rows in the flow direction of the fluid offset from one another in the flow channel are arranged.

Becomes a fluid passed through the forming die and / or die, so arise through the opposing structures at the crossing points and by the contour and arrangement of the channels and lands Water vortex. The water flows through the surface thus not laminar (as with conventional cooling holes and lines) but turbulent. The turbulent flow has the advantage of having a better cooling transfer by convection to the channel surfaces possible is. As a result, the temperature control can cool improved or also heat.

At the Mold hardening process is a body panel, for example from a high-strength FeMn steel such as 22MnB5, to temperatures of Heated to 1000 ° Celsius at 900 ° Celsius and inserted in the mold hardening tool. Then the Form hardening device closed and thereby with a pressing pressure from 200 to 2000 tons, preferably from 600 to 1000 tons applied. The sheet hardening takes place in the tool with cooling rates from 5 to 1000 K / s, preferably 20 to 80 K / s.

By suitable dimensioning and positioning of cooling channels inside the mold hardening tool it is possible different cooling rates in different areas of the body panel. So humbled by locally from the outer contour more distant cooling channels or a less dense local network of cooling channels locally the cooling rate, resulting in locally lower strengths of the finished component leads and higher ductility.

Farther it is also conceivable to mill separate sewer systems and in a first channel system, a fluid temperature of, for example 20 ° C and in another channel system, a fluid temperature to provide, for example, 200 ° Celsius. For big ones Temperature differences to be set on the outer contour the molding die or molding die, the core and the mold shell are preferred continue to segment and, where appropriate, such segments by weakly thermally conductive materials to connect to prevent an unwanted lateral heat flow.

By the differences in the cooling rate can so locally next to each other high-strength and ductile areas achieved in a single body sheet in the form hardening be what, for example, desired for side panels in the vehicle is. These should be as stiff as possible in a certain area be (torsional stiffness) and in other areas as possible ductile (crash absorbing area). So has such a body panel in a range a Vickers hardness of 200 HV10 and in one other area a Vickers hardness of 500 HV10.

In terms of The production time is the requirement, as possible to achieve a high clock rate. This clock rate is during mold hardening in particular by the cooling time of the molding die and / or molding die specified. In press hardening this gives up to 1000 ° Celsius Hot sheet metal component transfers its heat to the forming die and the shape of the mold. The goal is the mold die and / or form template as possible quickly cool back to a nominal temperature, which by a turbulent flow in the cooling channels (Vortex water cooling) is achieved. This allows in series production clock rates of less than 30 s, preferably 5 to 20 s can be achieved.

The The invention will be described below with reference to drawings and exemplary embodiments explained.

It demonstrate:

1 : a molding die or molding die 15 for hot forming with accurately assembled core 1 and shell mold 2

2 : a section of a nucleus 1 with fishbone shaped channels 5 and inlet and outlet openings 3 . 4 for fluids

3 : a section of a shell mold 2 with an opposing herringbone pattern

4 : Channel sections 5 with intervening bridges 6 of the core 1

5 : Channel sections 5 with intervening bridges 6 the shape shell 2

6 : Core 1 and shell mold 2 in the assembled molding die or molding die 15

7A . 7B . 8A . 8B : Cooling channels with circular and elliptical webs

9 : Circular and elliptical webs

10 : Mold segments with cooling channel and supply line

11 . 12 : Flow patterns on elliptical and circular webs

13 : a cooling water supply

14 : an arrangement of the supply line to the webs

15 . 16 : the cooling curve of a sheet produced by the process

17 : a core 1 for a mold shell 2 with three-dimensional introduced channel structures 5

18 : the shape shell 2 with visible channel-shaped inner contour.

A molding die for hot working or tempering according to the present invention 1 , The form patrix 15 includes at least two segments, one core 1 and a mold shell attached thereto 2 , The outer segment, the shape shell 2 forms the contour 14 of the component to be manufactured, in particular body component, towards the outside.

Due to the construction by means of at least two segments, only the shell mold must 2 made of a high-quality heat-resistant, heat-resistant and tough thermally conductive steel such as Cr-Mo-V or Ni-Cr-Mo-V steel, whereas the core 1 Made of low-cost steel, such as gray cast iron. Steels which have a thermal conductivity of 40-70 W / mK and a heat capacity of 300-800 J / kgK, in particular, are suitable for the selection of the tool material zugt 400-500 J / kgK have.

To the core 1 are, as in 1 seen, a supply line 7 and a derivative 8th attached, through which a tempering fluid is passed. These lines open into an inlet opening 3 and an outlet opening 4 in the form pattern inside, as in 2 shown. These openings 3 . 4 stand with the milled flow channels 5 in connection.

As the 3 to 6 show, the patterns of the flow channels run 5 in the core 1 and shell mold 2 preferably in opposite directions. As a result, the fluid flows through both the flow channels in the core 1 as well as through flow channels in the shell mold 2 , At the points of intersection of the structures, transverse components of the fluid flow are created which cause turbulence of the fluid and thus a turbulent flow.

A cooling channel or flow channel 5 according to the embodiments according to the 7A to 8B is formed by a flat cavity in the mold shell 2 or the core 1 is milled. For mutual support of mold shell 2 and core 1 are offset to each other positioned webs 6 arranged on the hollow surface. Between the bridges 6 the fluid flows through the flow channel 5 and is swirled at the webs. The degree and the degree of turbulence is influenced in particular by the geometry of the webs. So shows 9 that a circular bridge 6 a different (Um) flow behavior compared to an elliptical web 6 conditionally. In the 9 webs shown are in the flow direction 19 incident flow.

As a result of friction on the webs 6 In the vicinity of the bridge, the flow velocity of the fluid slows down and a local increase in pressure in the fluid, through which the fluid particles near the wall of the webs 6 additionally be braked. The flow on the body comes to a standstill and there is a backflow while the outside flow continues to flow forward. This retrograde current forces the flow at the separation point 17 to detach from the body wall. Downstream of this point flows at the dock 6 the fluid against the flow direction and curls up into a vortex. The nature and strength of this swirling depends heavily on the dimensioning of the webs 6 , the channel cross-section, the flow rate of the fluid, the flow characteristics of the fluid, and the surface topography of the channel walls and lands.

So can change the position of the separation point thereby Be that similar to the surface of the bridge of a golf ball is provided with dents or bumps, which at these Aus- or indentations in the surface local Small turbulences occur. This is possible as well in circular webs a similar flow pattern as to produce elliptical webs.

It will be advantageous for the bars 6 and the flow channel 5 chosen a height of 3 mm to 40 mm, preferably 10 mm to 20 mm.

Becomes Water used as cooling fluid, so should a cooling water flow rate from 10-200 l / min, preferably 20-40 l / min become.

The 11 and 12 show simulated simulated flow patterns of the fluid in circular and elliptical webs. In this case, elliptical webs have a less pronounced detachment behavior, with a smaller detachment / swirling area 20 ,

For a segmented tool with water cooling, circular webs with a diameter of 10 mm to 100 mm and elliptical webs with half-axis sizes a: 5-50 mm and b: 10-100 mm, as in FIG 8A shown used.

In order to achieve a uniform temperature of the tool, the flow channel 5 the outer geometry 14 follow the form shell, like 10 shows. On the one hand to ensure sufficient stability during hot forming and on the other hand a good heat transfer between the shell mold 2 and to ensure tempering medium, the mold shell should be 2 as in 10 represented above the flow channel 5 have a thickness of 5-50 mm, preferably 15-25 mm.

The supply line 7 or derivative 8th the fluid, in particular cooling water, is introduced through the core into the flow channel, this introduction advantageously taking place at a plurality of points. From the point of introduction, the cooling water flows through the flow channel / cooling channel 5 and cools the mold shell or top shell 2 which absorbs and dissipates the heat of the hot plate, as in 13 shown.

It will be advantageous, as from 14 visible, the supply lines in the flow direction in front of the webs 6 positioned, so that already occurs near the place of introduction of the cooling water swirling. Structurally are the supply lines 7 and derivatives 8th also as close as possible to the segment transitions between the core 1 and shell mold 2 to install, because such thermal bridges can be avoided. Furthermore, it proves to be advantageous, in front of a large part of the webs 6 to provide a supply line, and the inlet opening 3 and outlet opening 4 equal dimensioning to pressure differences in Strö flow duct 5 to avoid.

at the method according to the invention for hot forming or mold hardening of a component, in particular sheet metal component is heated to over 900 ° C sheet metal part in the Forming die or Formpatrize introduced. Then either the already preformed sheet metal part while keeping its contour in the mold cooled, or it is done before this hardening a final molding in the tool.

15 and 16 show cooling curves 18 a sheet metal part produced in this way. In such a segmented tool can be, as 15 shows cooling rates of 1000 k / s in the hardening process. After 5 seconds, cooling of the sheet metal part from over 900 ° C to 100 ° C has taken place. By choosing very good heat-conducting materials, a cooling within 3 s is possible. In the further process, an approximately linear cooling, such as 16 shows. With the inventive method of cooling by Kühlmittelverwirbelung the tool after 30 s, in particular 10-20 s the next clock can be supplied. The cooling achieved after 10 seconds, 15 seconds, 20 seconds, 25 seconds or 30 seconds is essentially determined by the coolant temperature and the coolant flow rate, given the cooling channel contour 15 and 16 demonstrate.

Flow channel patterns on a near-production tool show the 17 and the 18 , This can be done to the core 1 supply lines 7 . 8th be connected for the fluid leading to openings 3 . 4 lead in the channel structure. The openings open into larger cavities in the Formpatrize in the form of basins 9 , which with the flow channels 5 in core 1 or shape shell 2 are connected.

The pressing forces between core and shell are made by webs 6 , upper 13 and lower 12 Contact surfaces and lateral contact surfaces 16 collected. To secure the die against fluid leakage is a circumferential seal 11 intended. An attachment of the shell mold 2 at the core 1 done by fasteners 10 , such as screw anchors or hydraulic clamping connectors.

In The same way as the shaped die described can also be a molding die be designed.

1

core

2

shell mold

3

inlet port

4

outlet

5

flow channel

6

web

7

supply

8th

derivation

9

pool

10

fastener

11

poetry

12

lower Touchpad

13

upper Touchpad

14

outer contour

15

forming die or form patrix

16

bearing surface

17

transfer point

18

cooling curve

19

flow direction

20

Transfer / fluidization

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 8812140 U1 [0006, 0010]
• - DE 19810304 C1 [0007, 0010]
• - DE 19648708 A1 [0008, 0010]
• DE 10230837 A1 [0009, 0010]

Claims (18)

Molding or molding die 15 for hot forming or form hardening of a component, in particular a body panel, having an outer contour which has a shaping effect on the component to be machined, characterized in that the molding die or molding die 15 from at least two segments 1 . 2 where at least one of the segments is at the interface 12 . 13 to the other segment has recesses, such that through these indentations in the forming die or Formpatrize flow channels 5 are formed, which allow a temperature adjustment by means of a tempering medium, in particular coolant. Forming die or shaped die according to claim 1, characterized in that one of the segments has an outer shell 2 forms, the outward shaping outer contour 14 the molding die or molding die 15 having. Forming die or shaped die according to claim 1, characterized in that one of the segments as the core 1 is formed, which carries the other segment. Forming die or molding die after one of the preceding Claims, characterized in that the indentations form a channel pattern. Forming die or shaped die according to claim 4, characterized characterized in that a serpentine pattern is formed is. Forming die or shaped die according to claim 4, characterized characterized in that a herringbone pattern is formed. Forming die or shaped die according to claim 4, characterized in that the channel pattern through a flow channel 5 with stakes offset from one another 6 is formed. Forming die or shaped die according to claim 7, characterized in that the circular webs 6 with a diameter of 10-100 mm in the flow channel 5 are arranged. Forming die or shaped die according to claim 7, characterized in that the elliptical webs 6 with a half-axis size a of 5-50 mm and a half-axis size b of 10-100 mm in the flow channel 5 are arranged. Forming die or shaped die according to one of the preceding claims, characterized in that contacting segments 1 . 2 flow channels 5 have, which are arranged to intersect each other such that a turbulent fluid flow with components perpendicular to the contact surfaces 6 . 12 . 13 the segments 1 . 2 is achieved when flowing through. Forming die or shaped die according to one of the preceding claims, characterized in that the indentations the surface contour of the outer contour 14 consequences. Forming die or shaped die according to one of the preceding claims based on claim 2, characterized in that the mold shell 2 made of a high quality tool steel, in particular a hot work tool made of CrMoV or NiCrMoV. Forming die or shaped die according to one of the preceding claims dependent on claim 3, characterized in that the core 1 cast iron or cast steel. Method of hot forming or tempering a component, in particular a body panel, comprising the method steps: - bring in the heated sheet metal part into the forming die or die, - final forms or holding the sheet metal part in the tool - Cooling down and thereby curing the component in the mold - removal of the component from the mold - cooling the tool characterized in that the hot forming or Form hardening of the component in a molding die or molding die is made of at least two segments, through which a Temperiermedium such with turbulent flow rates and such a distribution is performed that a clock rate for the mentioned process steps of less than 30 s, is achieved in particular between 5 and 20 s. Method according to claim 14, characterized in that that the tempering medium between the at least two segments to be led. Method according to claim 14 or 15, characterized that the cooling from 900 ° C to 100 ° C 3 s to 5 s. Method according to one of claims 14-16, characterized in that a temperature gradient in the molding die and / or Formpatrize is set during pressing. Method according to one of claims 14 to 17, characterized in that in at least a partial area a component cooling rates of 5 to 1000 K / s, preferably 20 to 80 K / s can be achieved.