Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J7/00—Hammers; Forging machines with hammers or die jaws acting by impact
  • B21J7/02—Special design or construction
  • B21J7/14—Forging machines working with several hammers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J13/00—Details of machines for forging, pressing, or hammering
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
  • B21K1/00—Making machine elements
  • B21K1/06—Making machine elements axles or shafts
  • B21K1/063—Making machine elements axles or shafts hollow
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D7/00—Modifying the physical properties of iron or steel by deformation
  • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working

Definitions

• deformable material in particular steel
• the invention relates to a method for hot forging a seamless
• Hollow body made of difficult to deform material in particular of steel, according to the preamble of claim 1.
• the invention relates to a produced by hot forging tube made of a difficult to deform material.
• Characteristic of the production of seamless tubes from a heated block by hot rolling are the three steps punching - stretching - reducing rolls.
• Reduzierwalzen is replaced by a forming step in the form of a
• Radialschmiedereaes using an inserted into the hollow block inner tool and at least two on the lateral surface of the hollow block acting forging jaws a forging machine, wherein the hollow block clocked in the phase of the idle stroke of the forging jaws is rotated and moved axially.
• the rotation and the axial feed of the hollow block can take place simultaneously or with a time offset.
• tubes with a circumference of more than 500 mm and lengths of more than 4000 mm can be produced very advantageously.
• the method is not optimally designed for the forging of difficult-to-form materials.
• metallic materials, especially steels understood that at the forming temperature, ie the forging temperature, a yield point of more than 150 MPa determined at 0.3 logarithmic strain and a
• these are steels with chromium contents of more than 5.0% by weight, duplex steels, nickel-base alloys or refractory metals.
• Usual forging temperatures are depending on the material to be forged at least 70% of the respective melting temperature of the material.
• the forging temperature of the Inconel 718 material is at least 850 ° C.
• the forge can be a
• Mandrel body is on a support rod, also called mandrel, attached, with the mandrel body in the phase of the idle stroke in the hollow block can be moved axially or rotated.
• a support rod also called mandrel
• sufficiently long service life of the forging mandrel and consistently high quality of the inner surface of the tube can not yet be ensured in materials which are difficult to form.
• German Patent Application DE 10 2012 107 375 A1 already discloses a device for forging a hollow body with forging tools arranged centrally and symmetrically about a forging axis.
• a rotary drive can be controlled via a control device as a function of the rotational position of the forging mandrel relative to the forging tools.
• the object of the invention is an improved method for producing a seamless hot-finished metallic hollow body by hot forging
• this object is achieved by a method for hot forging a seamless hollow body made of difficult-to-form material, in particular steel, having a yield point at forming temperature of more than 150 MPa determined at 0.3 logarithmic strain and a
• Forming rate of 10 / s by means of hot forging which is characterized in that the hot forging is carried out with a forming degree in the forged section with ln (A0 / A1) of less than 1, 5 and a process-related strain rate of less than 5 / s, A0 as a local cross-sectional area of a hollow body to be forged in m 2 and A1 as a local cross-sectional area of the finished hollow body in m 2 and the
• Deformation rate as maximum speed of the hollow body to be forged in m / s based on the outer diameter of the finished forged hollow body in m are defined.
• the service life of the forging mandrel can advantageously be improved by using a forging mandrel made of a material having a strength of at least 700 MPa at 500 ° C.
• hot forging is characterized by the fact that the hollow body located at the forging temperature has a forging mandrel attached to a mandrel as an internal tool, by means of a forging axis arranged symmetrically and drivable in the radial strokes acting on the shell surface of the hollow body and the forging mandrel
• Schmiedebacken a forging machine is formed into a tube with a tube circumference of on average at least 500 mm and a length of at least 4000 mm, the hollow body clocked in the phase of the idle stroke of the
• the proposed method has the advantage that now hollow body made of difficult to transform materials with optimum inner surface can be produced economically, at the same time significantly increased service life of the forging mandrel.
• the proposed forging process is particularly effective and qualitatively favorable if, depending on the pipe diameter to be forged, two, four or more forging jaws are used, which act in a plane synchronously on the lateral surface of the hollow block.
• the inserted as an internal tool in the hollow block forging mandrel can in principle be arranged freely movable in the hollow block. For better distribution, in particular the thermal load, but it is advantageous to rotate the forging mandrel in the phases of idle strokes and / or to move in the same direction or opposite to the axial feed of the hollow block.
• the forging mandrel is rotated by means of a controller or a controller and / or moved in the axial direction, because it is then possible to specifically homogenize the thermal and mechanical load of the forging mandrel.
• the axial mandrel speed is either constant or variable.
• the rotation of the forging mandrel should be so large that in the following forging stroke the loads act on a region of the forging mandrel, which were without or with little impact in the previous forging.
• the direction of rotation of the forging mandrel can be selected equal to or different from the direction of rotation of the hollow block.
• Forging mandrel and hollow block are larger and thus heat welding of the workpiece with the forging mandrel can be better prevented.
• the forging mandrel may additionally be provided with a coating consisting of a ceramic, for example Tungsten carbide, and having a layer thickness of at least 0.02 mm and a maximum of 0.2 mm has a surface hardness of at least 900 HV0.1 at room temperature.
• a coating consisting of a ceramic, for example Tungsten carbide, and having a layer thickness of at least 0.02 mm and a maximum of 0.2 mm has a surface hardness of at least 900 HV0.1 at room temperature.
• the coating according to the invention relates to a tribologically acting layer, which by its thickness in the area mentioned both the necessary
• abrasion resistance also achieves heat welding of the hollow block on
• the release agent and / or lubricant may be applied to the inside of the hollow block before the start of the radial forging process and / or the
• Forging mandrel is lubricated at least in the area of the forging jaws acting on it before or during forging.
• Inner surface of the hollow block amount of not less than 40 g / m 2 .
• Direction of rotation of the forging mandrel and the hollow block of the forging mandrel a twice as high rotation step between the Umformh Claus is advantageous than uneven direction of rotation. This is because the contact surface of the forging jaw and thus the contact surface on the mandrel is always slightly asymmetrical to the longitudinal axis of the forging jaw and thus the lubricant is more easily pressed into the incoming zone and stripped from the mandrel. This is at the same direction of rotation significantly larger (about twice as large) rotation step of the mandrel necessary to bring the release agent and / or lubricant in the forming zone.
• Forging mandrel and DSH is the turning step in angular degree of the hollow block. It has been found that the width of the contact zone of the forging mandrel is significantly lower than that of the forge. Falling below the above limit leads to investigations on massive thermal stresses on the mandrel, which usually lead to plugs and thus to a failure of the process.
• the forging mandrel is thermally stressed by two influences before contact during forging.
• the radiation load through the warm workpiece and on the other hand by the introduced in the contact zone with the forging mandrel amount of heat.
• the thermal loads can be adjusted by the variability of the mandrel speed such that equalization of the introduced heat sufficiently reduces the maximum temperature of the mandrel surface to prevent plastic deformation or premature wear of the forge mandrel.
• Hollow blocks in the forging machine in m / s and GA discharge speed of the hollow block into the forging machine in m / s.
• the forging mandrel can be solid or designed as a hollow body.
• Forging is cooled from the outside to further reduce the thermal load.
• the wall thickness should be at least 9% for an internal cooling and at least 15% of the outside diameter of the forging mandrel for external cooling.
• the forging mandrel should have a length calculated as follows:
• forging a forging mandrel which has a conicity of at least 1: 1000, with the larger diameter at the mandril end of the Forging mandrel. Compliance with the specified conicity is necessary because the forged workpiece cools behind the forming zone such that a
• a further advantageous embodiment of the invention therefore provides that in terms of compliance with the tolerance requirements for inner or outer diameter and wall thickness of the hollow body, which by the conicity of
• Forging mandrel diameter conditional geometric deviation of the hollow body during forging is compensated by adjusting the stroke of the forging hammers.
• Diameter between forging mandrel and hollow block in m and HL represent the length of the hollow block in m.
• the inner diameter and the inner contour over the length of the forged hollow body are determined essentially by the geometry of the inner tool, preferably in the form of a cylindrical dome.
• Forming of the forging tools and / or a special control of the strokes of the forging hammers and the axial movements of the forging mandrel in addition to outside and inside round tubes also produce axisymmetric tubes, for example, as rectangular or square hollow body, even the used hollow block may have a corresponding geometry, so that the necessary forming work during forging of the finished part can be reduced to a minimum. Furthermore, the cross sections of both the hollow block used and the forged hollow body can change over the length.
• a diameter-graduated dome is conceivable with which, for example, stepped or / and conical cylinders with thickened ends can be produced over the length.
• stepped or / and conical cylinders with thickened ends can be produced over the length.
• stepped or / and conical cylinders with thickened ends can be produced over the length.
• several stepped cylinder from a hollow block would be possible.
• the hollow block is not formed as a hollow body open on both sides, but on one side has a bottom. This results in comparison to a hollow body open on both sides to a performance improvement in forging and is also advantageous if the finished part should also have a bottom.
• the finished forged hollow body is after the usual adjustment steps, such as cutting to length, visual inspection, marking, etc. either immediately deliverable or is still subjected to a heat treatment and / or non-destructive testing.
• the heat treatment may be normalizing or tempering. Depending on the straightness requirement, straightening is required.
• over-sanding or other suitable chip removal of the outer surface may be necessary to eliminate the small bumps caused by the forging process.
• Figure 1 shows the inventive method in a schematic representation
• FIG. 1 shows the method according to the invention in a schematic representation in a longitudinal section with a hollow block 1 to be forged having an initial cross-sectional area AO, which enters the forging machine from the left and leaves the forging machine on the right as a ready-to-use tube 2 with a local cross-sectional area A1.
• the forging takes place with a degree of deformation in the forging section in the forged section with ln (A0 / A1) of less than 1/5 and a process-related rate of deformation of less than 5 / s, the rate of deformation being the maximum tool speed in m / s relative to the outer diameter of the finished forged hollow body is defined in m.
• the forging mandrel 4 is made of a material having a strength of at least 700 MPa at 500 ° C and is held in place by a support rod 5, but may alternatively be axially moved back and forth during the forging process and / or rotated.
• the direction of rotation of the forging mandrel can be in the direction of rotation of the hollow block or opposite.
• the forging mandrel 4 is designed as a solid body with a taper of more than 1: 1000 and is cooled only from the outside.
• Each forging jaw 3 to 3 "' has in longitudinal section a predominantly conically shaped inlet section 8 and a subsequent smoothing section 9.
• the inlet section 8 can also be slightly convexly curved.
• all the forging jaws 3 to 3 "' have a concave curvature, as a rule, the curvature is a circular arc whose radius is greater than the current radius of the part to be forged.
• the movement arrows 10 shown in FIGS. 1 and 2 are intended to illustrate the radial stroke of the respective forging jaw 3 to 3 "'.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Forging (AREA)

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• 2013
  • 2013-09-25 DE DE201310219310 patent/DE102013219310A1/de active Pending
• 2014
  • 2014-09-23 EP EP14772322.5A patent/EP3049200B1/de active Active
  • 2014-09-23 WO PCT/EP2014/070208 patent/WO2015044120A1/de active Application Filing
  • 2014-09-23 CN CN201480049890.3A patent/CN105592954B/zh active Active
  • 2014-09-23 BR BR112016003146-6A patent/BR112016003146B1/pt active IP Right Grant

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