DE102015100801B4 - Compression device and method each for the electrical dipping of workpieces - Google Patents

Abstract

Stuffering device (1) for electro-upsetting, preferably elongated or rod-shaped, workpieces (2)
a) an upsetting unit (14, 19, 20, 21) for applying an upsetting force (FS) on a workpiece (2) between a first support surface (2a) and one of the first support surface (2a) facing away from the second support surface (2b) of the workpiece (2) during an upsetting process and
b) a first electrode unit (5, 6) and a second electrode unit (7, 8) for electrically heating a deformation region (28) of the workpiece (2) lying between them to at least one forming temperature during the upsetting process,
c) wherein the upsetting unit has a compression body (19) which is axially movable or moved in at least one feed direction (V) and has at least one first support surface (190) for the first support surface (2a) on the workpiece (2) and at least one feed direction (V). movable or moving escape body (11, 14) with at least one second support surface (110) for the second support surface (2b) on the workpiece (2) and an adjusting device (40) with the compression body (19) and the escape body (11) in Operative connection is or can be brought to provide an axial distance in the feed direction (V) between the support surfaces (190, 110) of compression body (19) and escape body (11),
d) wherein the first electrode unit (5, 6) from the second support surface (110) at a constant axial distance (a _const ) at least during the upsetting axially spaced from the feed direction (V) is arranged and with the escape body (11) of the compression unit is mitbewegbar and
e) wherein the second electrode unit (7, 8) between the first electrode unit (5, 6) and the first support surface (190) on the compression body (19) is arranged and at least during the compression process is arranged at a fixed axial position.

Description

The invention relates to a compression device and a method in each case for the electrical dewing of workpieces.

In the product information brochure "Electro-upsetting machines" from Lasco Umformtechnik GmbH, published in October 2012, the massive forming process of electro-upsetting is described. When electro-upsetting a workpiece between a driven via a hydraulic cylinder compression body and an anvil electrode is arranged. A rod portion of the workpiece is bounded by the anvil electrode at the end of the workpiece and another contact electrode, and a high electrical current flows through the rod portion at low AC voltage. Due to the high current density and the ohmic resistance of the material, the rod section heats up. Simultaneous feed via a hydraulic cylinder in a compression direction generates a volume accumulation in the heated rod section. As the volume of material increases, the distance between the electrodes increases and the anvil electrode recoils to make room for the volume change.

A distinction is made between free diving, in which the change in volume of the adjacent to the anvil electrode end portion of the workpiece is done by controlling the increase in the distance of the electrodes, and form upsetting, in which the volume change takes place in a die or a mold, which thus dictates the outer shape of the swaged portion , as well as die diving, which is a mixture of free diving and diving.

Advantages of this electro-upsetting, as compared to other forging operations such as hammer forging or forging or forging rolls, are accurate volume retention and high forming quality, with no burrs and in the grain of the workpiece, low specific energy consumption and waste of material since only the area to be reshaped is heated and no other areas be damaged or removed, hardly any tinder accumulation and no burden on people and the environment by transported hot forgings and their radiant heat, by mechanical shocks or noise.

The DE 960 946 B already deals with a free-diving method for electrical upsetting of workheads between an anvil electrode and a guide electrode by automatically adjusting the distance of the electrodes depending on the Stauchkopfform to be generated, wherein the change in distance is controlled by comparing the generated with the Stauchkopfform to be produced.

Furthermore, the describes DE 916 721 B a method for electric diving, in which the workpiece is heated transversely across clamping electrodes and longitudinally heated via clamping and anvil electrodes.

Out DE 1 240 369 B is now known a device for electrical dipping of cylindrical or prismatic finished shapes approximately in the middle of the rod, consisting of a closed die with a die hole used to control the compression pressure during upsetting receded Anvil piece for the one power supply side and an electrode and a printing device on the other power supply side , It is therefore a form upsetting.

Out JP S59-130 641 A For example, there is known a method of electric diving in which the end of a rod is gradually extruded by advancing a pressing member to expand the rod in the open space between the electrodes to a spherical shape. A moving device is then actuated to drive the electrodes to widen the space from the electrodes and to grow the spherical bulge to the side of the electrode, thereby forming a circular cylindrical bulge.

The JP 2006 - 297 441 A discloses an electrical device for electric diving with first electrodes and second electrodes that can approach each other or remove one another, a transformer T for electrical heating and a compression shaft for compression of a blank.

The known electro-upsetting devices and methods are suitable either only for end-dipping of end portions of the workpieces and not for electric diving in central areas or inner areas, ie workpiece areas, which are spaced from the ends of the workpiece, or they are only using dies for electric diving in Can be used in the middle areas of workpieces.

The present invention is based on the object of specifying an apparatus and a method which are preferably expanded (or elongated, elongated) for free diving in inner regions or central regions of workpieces, in particular at least prior to upsetting in a longitudinal direction or along a workpiece axis. in particular rod-shaped, workpieces, can be used advantageously.

To achieve this object suitable embodiments and objects according to the Invention are specified in particular in the patent claims, which are directed in particular to a compression device for the electrical dewing of workpieces, in particular with the features of claim 1, and a method for the electrical dewing of workpieces, in particular with the features of claim 7.

The claimable feature combinations and articles according to the invention are not limited to the selected version and the chosen back-links of the claims. Rather, each feature of a claim category, such as a device, may also be claimed in another claim category, such as a method. Furthermore, each feature in the claims, even independently of their relationships, may be claimed in any combination with one or more other feature (s) in the claims. In addition, any feature described or disclosed in the specification or drawings may be per se, independent or detached from the context in which it is described, alone or in any combination with one or more other features, or in the claims are described in the description or drawing or disclosed or are claimed.

The compression device according to claim 1 is suitable and intended for electric upsetting of preferably elongate or rod-shaped workpieces and comprises an upsetting unit for applying an upsetting force to a workpiece between a first support surface and a second support surface of the workpiece facing away from the first support surface during an upsetting operation and one first electrode unit and a second electrode unit for electrically heating a deformation region of the workpiece lying between them to at least one forming temperature during the upsetting process.

The compression unit has an upsetting body which is axially movable or moved in at least one feed direction and has at least one first support surface for the first support surface on the workpiece and an evasive body movable or moved at least in the feed direction with at least one second support surface for the second support surface on the workpiece and an adjustment device : Control device, control or regulating device), which is in operative connection with the compression body and the escape body, for setting (or: controlling, controlling) an axial distance in the feed direction between the support surfaces of compression body and escape body, on.

The first electrode unit is arranged so as to be axially spaced from the second support surface by an axial distance, which is constant at least during the upsetting operation, and can be moved along with the escape body of the compression unit.

The second electrode unit is arranged between the first electrode unit and the first support surface on the upsetting body and arranged at a fixed axial position at least during the upsetting process.

A method according to the invention for the electrical dipping of, preferably elongated or rod-shaped, workpieces is specified in claim 7. In this method, a workpiece is subjected to an upsetting force between a first support surface and a second support surface facing away from the first support surface and a deformation region of the workpiece spaced between the two support surfaces and spaced from both support surfaces by means of an electrical heating current flowing through the deformation region at least one forming temperature is heated and by the simultaneous application of the compressive force in a free-forming process, ie without die, is compressed and is increased by re-flow or tracking of material of the workpiece in its shape or its volume or its cross-section. The heating current is introduced in particular by means of a first electrode unit and a second electrode unit which are brought into electrical contact with the workpiece at respective contact surfaces of the workpiece spaced from the support surfaces.

By matching the movement speeds or the relative speed, for example as a continuous movement speed of the compression unit and as a variable movement speed of the first clamping electrode unit or vice versa, and the heating current certain geometries can be generated at the deformation range of the workpiece. In particular, by suitably setting the movement speeds of the upsetting unit and the first clamping electrode unit, the forming speed and / or adjustment of the upset force resulting from the initial upsetting force and the relative movement or also the force regulation can be adjusted in the shape change area. In particular, with the apparatus and method according to the invention, there is provided an electric free-diving in an inner region, ie an end-spaced region, of a workpiece which could be termed center-line diving and where no die needs to be used, ie no spatial limitation is provided by a die for the workpiece between the electrode units, but rather the workpiece is freely malleable or free in its volume can be changed. The above-mentioned advantages of electric upsetting also apply to the electric diving according to the invention.

In an advantageous embodiment, the first electrode unit comprises at least two clamping electrodes for clamping on first, preferably two diametrically and / or vertically opposite, contact surfaces of the workpiece in electrically conductive contact and the second electrode unit at least two clamping electrodes for clamping to second, preferably two diametrically and / or horizontally opposite, contact surfaces of the workpiece in electrically conductive contact and further preferably an electrical supply unit for applying an electrical heating current between the clamping electrodes of the two electrode units, which heating current flows through the contact surfaces through the deformation area of the workpiece and this resistively heated to the forming temperature. Preferably, the adjusting device for free-forming the workpiece in the deformation range, the axial distance between the support surfaces of compression body and escape body in dependence on the heating current.

The first electrode unit can now in an advantageous embodiment for the first clamping electrode and for the second clamping electrode, in particular for the clamping electrodes associated carrier carriage, respectively assigned, designed in particular as hydraulic piston actuators, actuators for laterally or radially to the feed direction directed movement of the clamping electrodes and for adjusting the over their clamping surfaces on the workpiece exerted clamping pressure, wherein at least one actuator, in particular an actuator for an upper clamping electrode, a mechanical locking unit is assigned for locking the actuator and thus the associated clamping electrode in his or her radial position.

In a further advantageous embodiment, the second electrode unit is associated with or comprises a centering clamping unit which has two Zentrierspannelemente which are symmetrical about a synchronization device with respect to a centering axis, which extends in particular during the upsetting process by the workpiece, toward or away from each other, and preferably linearly guided against each other and / or driven by pressurized pistons, wherein on or on a first of the two Zentrierspannelemente a clamping electrode of the second electrode unit and on or on a second of the two Zentrierspannelemente or another clamping electrode of the second electrode unit is attached or held.

Conveniently, the escape body on a spacer on which the at least one second support surface is formed, being adjustable over the choice of the axial length of the spacer or the use of spacers of different axial length during the upsetting constant axial distance of the first electrode unit of the second support surface is.

Preferably, the escape body and / or the spacer are or at least partially formed electrically insulating and thereby flows through with adjacent heating current from any appreciable electric current.

In the method according to the invention, a compression device according to the invention is preferably used.

In one embodiment of the method, one or the upsetting body of one or the upsetting unit is brought with its at least one first support surface in abutment or contact with the first support surface on the workpiece and one or the escape body with its at least one second support surface in abutment or contact with the second support surface on the workpiece brought. By means of one or the adjusting device, the axial distance in the feed direction between the support surfaces of compression body and the escape body during the upsetting process is reduced, in particular by the compression body is moved in the feed direction at a greater speed than the escape body, whereby the compression force is generated or maintained. In this case, the first electrode unit is held or spaced from the second support surface by a predetermined axial distance, which is constant during the upsetting process, axially opposite to the feed direction and moved along with the escape body. By contrast, the second electrode unit is arranged between the first electrode unit and the first support surface on the upsetting body and arranged or held at a fixed axial position at least during the upsetting process, the workpiece slipping over a specific axial region during the upsetting process by the second electrode unit, in particular its clamping electrodes or slides under the action of a certain slip or sliding and / or static friction.

In particular, the shape of the deformation range is determined by the deformation temperature or by the heating current between the electrode units by the deformation range on the one hand and by the temporal velocity characteristics the speeds of compression body and escape body on the other hand controlled.

In a particular embodiment of the method, three special process steps during commissioning or setting up and contacting the workpiece at the beginning of the upsetting process are performed.

In a first process step at the beginning of a compression process, the workpiece is inserted or clamped between the support surfaces, wherein the two electrode units are not yet in complete contact with the workpiece.

In a second method step, the second electrode unit is brought into contact with the workpiece by means of the centering unit, whereby at least two clamping electrodes of each electrode unit, in particular by means of associated centering clamping elements, move symmetrically with respect to a centering axis or a centering point on the workpiece and in conductive contact on the contact surfaces pinch with a predetermined clamping force.

In asymmetric wear of the clamping electrodes, in particular due to abrasion or abrasion by slipping workpieces in previous compression processes, while a, in particular parallel or axially to the feed direction extending or arranged workpiece axis of the workpiece is moved to the centering axis by an amount dependent on the amount of wear.

In a third method step, the first electrode unit is brought into contact with the workpiece.

Preferably, in the third method step, initially only one or the first clamping electrode of the first electrode unit, in particular by means of one or, preferably hydraulic, actuator and / or in particular radially to the workpiece axis, moved against a contact surface of the workpiece and applied under a low contact pressure, so that the Workpiece is not substantially radially displaced or bent, but essentially remains in the centered in the second step of its workpiece axis position, and then locked in this position, in particular by means of one or the locking unit of the actuator.

Thereafter, in the third method step, one or the second clamping electrode of the first electrode unit, in particular by means of one or the associated, preferably hydraulic, actuator, is moved against one or the associated contact surface of the workpiece, and then the workpiece with a higher clamping pressure, in particular significantly higher as the system pressure, clamped between the two clamping electrodes.

In this way, a hydraulically decoupled holder for the workpiece is created, which defines the workpiece with a sufficient pressure force, whereby no evasive movements of the clamping electrodes produced by hydraulic connections between the clamping electrodes can occur. The concentricity of the axes right and left of the storage area can be ensured even after the upsetting process.

According to the invention, workpieces that have already undergone previous forming steps, in particular at one end by end upsetting, can also be processed advantageously. The area to be formed on the workpiece is determined by the placement of the electrode units and can be arbitrarily selected. A further advantage of the invention is that a free-form compression is made possible, wherein a die is dispensed with. A free-form compression is made possible in particular by the fact that the electrode units according to the invention execute an evasive movement in order to enable and to influence the change in volume.

In a development according to the invention, at least one clamping electrode or a clamping jaw thereof is cooled, in particular water-cooled, formed and / or formed from a material which conducts electricity well, in particular a material containing or comprising a copper alloy.

• 1 eine schematische Darstellung des Werkstücks, der elektrischen Heizeinheit und der Staucheinheit zu Beginn eines Stauchvorgangs,
• 2 eine schematische Darstellung des Werkstücks, der Heizeinheit und der Staucheinheit nach 1 nach Abschluss des Stauchvorgangs,
• 3 eine schematische Darstellung des Werkstücks, der Heizeinheit und der Staucheinheit zu Beginn eines Stauchvorgangs mit einer zu 1 alternativen Werkstückgeometrie,
• 4 eine schematische Darstellung des Werkstücks, der Heizeinheit und der Staucheinheit nach 3 nach Abschluss des Stauchvorgangs,
• 5 ein Ausführungsbeispiel einer Stauchvorrichtung in geschnittener Darstellung von der Seite,
• 6 ein Detailausschnitt der Stauchvorrichtung nach 5,
• 7 ein Detailausschnitt der Stauchvorrichtung nach 5 mit alternativer Werkstückgeometrie am Werkstückkopf,
• 8 eine Stauchvorrichtung gemäß 5 in perspektivischer Darstellung zu Beginn eines Stauchvorgangs und
• 9 die Stauchvorrichtung gemäß 8 in perspektivischer Darstellung am Ende oder nach Abschluss des Stauchvorgangs

jeweils schematisch gezeigt sind. Einander entsprechende Teile und Größen sind in den 1 bis 9 mit denselben Bezugszeichen versehen.The invention will be explained below with reference to exemplary embodiments. Reference is also made to the drawings, in whose

• 1 a schematic representation of the workpiece, the electric heating unit and the compression unit at the beginning of a compression process,
• 2 a schematic representation of the workpiece, the heating unit and the upsetting unit after 1 after completion of the upsetting process,
• 3 a schematic representation of the workpiece, the heating unit and the compression unit at the beginning of a compression operation with a too 1 alternative workpiece geometry,
• 4 a schematic representation of the workpiece, the heating unit and the upsetting unit after 3 after completion of the upsetting process,
• 5 an embodiment of a compression device in a sectional view from the side,
• 6 a detail of the compression device after 5 .
• 7 a detail of the compression device after 5 with alternative workpiece geometry on the workpiece head,
• 8th a compression device according to 5 in perspective at the beginning of a compression process and
• 9 the compression device according to 8th in perspective at the end or after completion of the upsetting process

are each shown schematically. Corresponding parts and sizes are in the 1 to 9 provided with the same reference numerals.

1 and 2 such as 3 and 4 show schematically in schematic diagrams each one at least before the compression process along a longitudinal axis (or workpiece axis) A preferably extended (or: elongated, elongated), in particular rod-shaped, workpiece 2 that in a compression device 1 is clamped or held and in a Formänderungsbereich (or: compression area) by electro-upsetting, ie by combination of electrical heating and (mechanical) upsetting, increased in volume or provided with a collection of material.

The compression device 1 first includes a compression body 19 and an escape body 11 having compression unit for applying an upsetting force FS on the workpiece 2 between a first support surface 2a and one of the first support surface 2a facing away from the second support surface 2 B of the workpiece 2 during a compression process. The compression body 19 is in a feed direction V movable or moved and has at least a first support surface 190 for the first support surface 2a on the workpiece 2 on. The escape body 11 is also in the feed direction V movable or moved and has at least a second support surface 110 for the second support surface 2 B on the workpiece 2 on. Between the support surfaces 190 and 110 is determined by the relative position of compression body 19 and evasive body 11 in the feed direction V directed upsetting force FS on the workpiece 2 built up. For this purpose, the compression unit comprises an adjusting device (or: control device, control and / or regulating device) 40 that with the compression body 19 and the escape body 11 is operable or engageable to provide (or: control or regulate) a distance or a relative position between the support surfaces 190 and 110 of compression body 19 and evasive body 11 and / or to set (or: control or regulate) the speeds v1 of compression body 19 and v2 of evasive body 11 in the feed direction V , preferably over in 1 to 4 not shown drives or actuators and possibly sensors.

Furthermore, the compression device comprises 1 a first electrode unit with two clamping electrodes 5 and 6 and a second electrode unit with two clamping electrodes 7 and 8th for electrically heating the between the two with the workpiece 2 contacted electrode units lying shape change range 28 of the workpiece 2 on for forming the material of the workpiece 2 suitable forming temperatures. The clamping electrodes 5 and 6 The first electrode unit are at first, preferably two diametrically and / or vertically opposite contact surfaces 2c of the workpiece 2 under a certain clamping or pressing force F ₅ respectively. F ₆ in electrically conductive contact. The clamping electrodes 7 and 8th The second electrode unit are at second, preferably two diametrically and / or horizontally opposite contact surfaces 2d of the workpiece 2 under a certain clamping or pressing force F ₇ respectively. F ₈ in electrically conductive contact. The term "clamps" is intended here also to include a basically conceivable embodiment in which only one side of an electrode is pressed against the workpiece in electrically conductive contact.

The first electrode unit with the clamping electrodes 5 and 6 is with the escape body 11 (kinematically) coupled, preferably via direct mechanical coupling or a mechanical connecting element or via a control technology coupling via the adjusting device 40 , Furthermore, the first electrode unit is with the clamping electrodes 5 and 6 preferably from the first support surface 110 on the escape body 11 by a predetermined, preferably constant, distance a _const in or axially to the feed direction V spaced apart. The first electrode unit with the clamping electrodes 5 and 6 is relative to the first support surface 190 on the compression body 19 and relative to the second electrode unit with the clamping electrodes 7 and 8th axially to the feed direction V movable and in the feed direction V axial distance to these changeable. This axial relative movement of the two electrode units is also preferred via the adjusting device 40 , preferably one in the 1 to 4 not shown drive or actuator and possibly sensor (s), causes or made.

The escape body 11 , which can be compared with the anvil in the prior art, is not electrically active, ie there is no appreciable electric current flowing through it and at the contact point between the support surface 110 and support surface 2 B into or out of the workpiece 2 ie the escape body 11 is not an anvil electrode as in the prior art.

1 shows a situation at the beginning of a swaging operation at a time t0. The workpiece 2 is not yet formed, but has in the illustrated embodiment, a continuously constant, for example, round, cross-section and also has on its as a support surface 2 B on the support surface 110 adjacent end face in the end portion 22 the same cross section. At time t0, the workpiece has 2 along its longitudinal axis A measured length L (t0) and the to the longitudinal axis A axial distance between the two electrode units 5 and 6 on the one hand and 7 and 8 on the other hand (or correspondingly: between the contact surfaces 2c and 2d on the workpiece 2 ) a (t0) , The support surfaces 110 and 190 have by adjusting the axial positions of compression body 19 and evasive body 11 also the distance L (t0) , but at least an axial bias in the workpiece 2 and preferably already an upsetting force FS set. For this purpose, in particular a position control of the support surface 110 of the escape body 11 or a force control to a constant compression force FS with regard to the support surface 190 on the compression body 19 be provided. But there may also be other movement variables such as speeds or positions of support surface 110 of the escape body 11 and support surface 190 on the compression body 19 be managed.

It will now be an electric heating current I , preferably an electrical low-frequency alternating current, from the clamping electrodes 5 and 6 over the contact surfaces 2c into the workpiece 2 initiated, over the contact surfaces 2d back into the clamping electrodes 7 and 8th flows and the intervening strain range 28 of the workpiece 2 heated to the forming temperature (s). The current direction is only given by way of example and drawn in, but it changes periodically in the case of alternating current. The alternating voltage of the heating current I is, for example, in the range of 8 to 12 V and the current in the range of 10,000 to 65,000 A depending on the desired heating rate or cycle time and typically 5 to 60 Hz. However, a direct current can also be used. The workpiece 2 is due to this electrical heating in the deformation range 28 softer, ie reduced in its deformation resistance, and plastically deformable. In the remaining areas where the workpiece 2 not from a heating current I is traversed, it remains colder and not by the compression force FS formable.

It is now an upsetting process initiated by simultaneously applying the workpiece 2 with the electric heating current I between the two electrode units now by means of the adjusting device 40 the compression body 19 at a speed v1 that is a function of time t is, and the evasive body 11 at a speed v2 , which is also a function of time t is and less than the speed v1 is set, respectively in the feed direction V to be moved. The compression force FS now leads to a deformation in the electrically heated and thus made soft or deformable deformation range 28 , This deformation leads to a material accumulation or compression or increase in volume in the deformation range 28 which is also due to the increase of the longitudinal axis A measured maximum width b ₁ of the workpiece 2 in the deformation range 28 compared to the original width measured in the other areas b ₀ can recognize.

The shape of the deformation area 28 is determined by the forming temperature, ie by the heating current, and by the speed characteristics v1 and v2 depending on the time t and / or by the compression force FS determined and controlled. To the Nachfließen and the accumulation of the material in the shaping area 28 to allow and also to contact surfaces 2c and 2d on the workpiece 2 with constant cross-section (width b ₀ ) and the axial enlargement of the deformation range 28 To take into account, the axial distance between the two electrode units is increased.

2 shows by way of example a situation at a time t1> t0. It is a frusto-conical shape in the deformation area 28 been generated. But there are many different shapes or shapes can be generated. The compression body 19 became the feed path ΔL1 and the escape body 11 became the feed path ΔL2 in the feed direction V moved on, where ΔL1 > ΔL2 corresponding to the course of the mean velocities v1> v2. The compressed or shortened length of the workpiece 2 and the corresponding distance of the support surfaces 110 and 190 is now L (t1) = L (t0) - ΔL1 + ΔL2 , The axial distance between the two electrode units 5 and 6 on the one hand and 7 and 8 on the other hand and thus the contact surfaces 2c and 2d on the workpiece 2 is enlarged by a (t0) in 1 on a (t1) in 2 , where the difference a (t1) - a (t0) at least approximately equal to the difference L (0) - L (t1). The distance a (t1) also corresponds to the axial length of the deformation range 28 , The distance between the first electrode unit 5 and 6 and the support surface 110 on the escape body 11 or the distance between the support surface 2a and contact surfaces 2c on the workpiece 2 has remained the same and continues to be a _const , as in 1 at the time t0 ,

3 differs from 1 and 4 differs from 2 only in that the workpiece 2 in the end section 22 in 3 and 4 one opposite 1 and 2 enlarged cross section has, for example, a bell or trumpet-shaped magnification, with a correspondingly larger support surface 2 B on the front side on the support surface 110 is applied. This shows that even with preformed, for example, upset, workpieces with the device and the method according to the invention even a mid-free diving is possible without changing the already preformed end portion.

The 5 to 9 show in greater constructive detail further embodiments according to the invention.

The compression device 1 now preferably has a frame 3 on with frame columns 3a and 3b , in each case in their end areas with carrier plates 4a and 4b are connected and so a rigid and low-distortion support structure for the compression unit and the heating unit of the compression device 1 form.

The escape body 11 is on the frame 3 via guides, for example on linear guides, axially or parallel to the longitudinal axis A or to the feed direction V slidably mounted, preferably with a bypass piston 13 connected in one to the carrier plate 4b attached alternate cylinder 12 is guided. bypass piston 13 and alternate cylinders 12 are preferably designed as a hydraulic unit and serve as an axial drive for the escape body 11 , The hydraulic unit made of alternative cylinders 12 and alternate piston 13 can also provide a well-defined counterforce available to the escape body 11 axially to the longitudinal axis A supported.

On the carrier plate 4a is a compression cylinder 20 fastened, in which a compression piston 21 is guided, creating a compression drive for the compression body 19 is formed, which the compression force FS or a feed force on the workpiece 2 in a direction along the feed direction V exercises. The compression body 19 takes the end section 27 of the workpiece 2 on and supports the compression force FS transmitting with its support surface 190 against the free support surface 2a on the workpiece 2 and is designed in particular as a push rod or push sleeve.

The opposite support surface 2 B at the other end section 22 of the workpiece 2 is here now preferably not directly to the escape body 11 supported as in 1 to 4 but lies on a support surface 140 , preferably at a free end, of a spacer (or spacer) 14 which contacts the escape body 11 axially moved and preferably at its other end to a support surface 114 on the escape body 11 axially supported and there is usually fixed by means of fasteners such as screws.

The support surface 140 of the spacer 14 is generally larger than the abutting support surface 2 B of the workpiece 2 also selected certain height differences in the longitudinal axis A orthogonal direction or deviations from the centering at the position of the workpiece 2 to be able to compensate.

There can be spacers 14 be provided different axial length or the spacer 14 be adapted in its axial length to adapt or determine the axial position of the deformation range 28 of the workpiece 2 in its axial distance to the end or the support surface 2 B without the electrode unit 5 and 6 must be moved. About the axial length of the spacer 14 So can the predetermined during the compression process constant distance a _const the first electrode unit with the clamping electrodes 5 and 6 from the first support surface 190 be set or changed.

The escape body 11 has in particular a recess or a free space 111 in, in or the spacer 14 sunk or is added and at the bottom of the support surface 114 is formed, in particular in a small depression. In this case, the escape body 11 as shown, for example, have a laterally open U-shape or a closed form, such as pot shape.

The spacer 14 and / or the escape body 11 are preferably formed in all embodiments at least partially of electrically insulating material, such as a glass fiber material. Due to the electrical insulation of the spacer and / or the escape body, the current provided for heating flows essentially exclusively through the deformation area 28 and the electrode units and no significant leakage current through the spacer 14 and the escape body 11 ,

• An Trägerflächen 23 und 24 des Ausweichkörpers 11 sind jeweils über einen Trägerschlitten 26 die erste Klemmelektrode 5 mit einer Klemmbacke 15 und gegenüberliegend die zweite Klemmelektrode 6 mit einer Klemmbacke 16 mittels zugeordneter, vorzugsweise hydraulischer oder als Hydraulikkolbenantriebe ausgebildeter, Aktuatoren (oder: Antriebe) 25 und 29 lateral oder radial zur Längsachse A zueinander verschieblich angeordnet und gehalten. Die von den Klemmelektroden 5 und 6 über deren an den Kontaktflächen 2c bzw. 2d am Werkstück 2 anliegende Klemmbacken 15 und 16 ausgeübte Klemmdruck oder Kontaktdruck oder die Andrückkraft, mit dem oder der das Werkstück 2 in elektrischem Kontakt gehalten wird, kann über die Aktuatoren oder Antriebe genau eingestellt werden. Außerdem sind die Klemmbacken 15 und 16 vorzugsweise der Außenfläche des Werkstücks 2 wenigstens annähernd angepasst.

The first electrode unit is preferably designed and arranged as follows:

• On support surfaces 23 and 24 of the escape body 11 are each via a carrier carriage 26 the first clamping electrode 5 with a jaw 15 and opposite the second clamping electrode 6 with a jaw 16 by means of associated, preferably hydraulic or hydraulic piston actuators, actuators (or: drives) 25 and 29 lateral or radial to the longitudinal axis A slidably arranged and held each other. The of the clamping electrodes 5 and 6 about their on the contact surfaces 2c respectively. 2d on the workpiece 2 fitting jaws 15 and 16 exerted clamping pressure or contact pressure or the Pressing force with which or the workpiece 2 is maintained in electrical contact, can be accurately adjusted via the actuators or drives. Besides, the jaws are 15 and 16 preferably the outer surface of the workpiece 2 at least approximately adjusted.

It is also at least the actuator 25 for the clamping electrode 5 a mechanical locking unit (or: locking unit) 125 assigned, preferably a piston brake for the hydraulic piston, this and thus the associated clamping electrode 5 respectively. 6 locked in the radial position. This allows the first clamping electrode 5 and / or the second clamping electrode 6 to the associated contact surfaces 2c moved up and under comparatively low clamping or contact pressure in contact with the workpiece 2 be brought and then locked or locked by means of the mechanical locking in this radial position or locked so that they can not radially outward drift or move. This will be at a hydraulic pressure equalization or equal pressure in the hydraulic actuators 25 and 29 the otherwise possible common drift of both clamping electrodes 5 and 6 prevented in the same radial direction and the centered position of the workpiece 2 in the first pair of clamping electrodes 5 and 6 remains. A special use of this function will be explained in more detail.

Axial to the longitudinal axis A or in the feed direction V is the first pair of clamp electrodes 5 and 6 , ie the first electrode unit, via the carrier carriages 26 and the support surfaces 23 and 24 at a fixed axial distance in 5 to 9 not marked, but the distance a _const in the feed direction V in 1 to 4 corresponds to the support surface 140 at the spacer 14 held, so moves with the escape body 11 and the spacer 14 in their evasive movement at the same speed v ₂ in the feed direction V With. As a result, there is virtually no relative movement between the first electrode unit and the workpiece during the upsetting process 2 and the jaws 15 and 16 be through the, often abrasive, workpiece 2 not or only slightly worn or worn out.

• Ein Trägerelement 10 ist in einer axialen Position festlegbar oder fixierbar an dem Gestell 3 axial zur Achse A und in und entgegengesetzt zu der Vorschubrichtung V verschieblich über Führungen an den Gestellsäulen 3a und 3b gelagert.

The second electrode unit with the clamping electrodes 7 and 8th is preferably formed and arranged as follows:

• A carrier element 10 is fixable in an axial position or fixable to the frame 3 axially to the axis A and in and opposite to the feed direction V movable via guides on the frame columns 3a and 3b stored.

On the support element 10 a Zentrierspanneinheit is mounted on or on a first Zentrierspannelement 9a the third clamping electrode 7 with its jaw 17 and on or at a second centering clamping element 9b a fourth clamping electrode 8th with its jaw 18 carries or holds. The centering clamping elements 9a and 9b are linearly guided against each other and driven by pressurized pistons and a sliding gear, a transmission of right and left rotation spindle or other synchronizing device symmetrically with respect to a centering axis toward or away from each other. An example of such a Zentrierspanneinheit results from DE 198 45 576 C2 or even out DE 20 2004 004 636 U1 , the disclosure of each of which is included in the disclosure of the present application. This will make the workpiece 2 between the jaws 17 and 18 the clamping electrodes 7 and 8th centered so that the workpiece axis or longitudinal axis A of the workpiece 2 coincides with the centering axis of Zentrierspanneinheit, and the clamping or contact forces F ₇ and F ₈ the two clamping electrodes 7 and 8th and their jaws 17 and 18 are set symmetrically or equal in magnitude and opposite to each other in the direction towards each other and can therefore be chosen comparatively high at such a uniform clamping.

In the upsetting process now slips due to the relative movement between the compression body 19 and the escape body 11 , eg from the distance a (t0) on the distance a (t1) in 1 to 4 , and the stationary second electrode unit, the workpiece 2 on the jaws 17 and 18 and, due to friction, generates wear or abrasion or abrasion on the lower jaw 18 due to the dead weight of the workpiece 2 usually larger than on the upper jaw 17 and with abrasive materials of the workpieces 2 can get pretty big.

The centering unit 9a and 9b compensates for this wear and carries both jaws 17 and 18 the workpiece 2 symmetric or centered to. However, the workpiece axis shifts A opposite the centering axis of the centering unit 9a and 9b then down, as is usually the abrasion on the lower jaw 18 is higher than at the upper jaw 17 and there arises a problem of no longer exact coaxiality of the second electrode unit with the first electrode unit and thus the intervening deformation region 28 of the workpiece 2 ,

To the coaxiality even with asymmetric wear of the jaws 17 and 18 Maintain according to the invention is preferably one special clamping or mounting method for the two electrode units provided.

At the beginning of a compression process, the workpiece becomes 2 for example, by a handling device, not shown, in the compression unit of the compression device 1 inserted, for example by placing it in the compression body 19 is inserted and placed on the open lower clamping electrodes. The clamping electrode pairs 5 and 6 and 7 and 8th are still open, so not on both sides or completely in contact with the workpiece 2 , Then, the workpiece becomes low in compression force 2 against the contact surface 26 pressed. The workpiece 2 but also between compression body 19 and evasive body 11 be clamped or inserted without any contact of the clamping electrodes.

In a now following method step, the second electrode unit is first of all by means of the centering unit with the workpiece 2 brought into contact. The third and fourth jaws move 17 and 18 with their associated Zentrierspannelementen 9a and 9b symmetrical to the workpiece 2 close and clamp this with centered workpiece axis A at the contact surfaces 2d in conductive contact with the desired (high) symmetrical clamping force F ₇ = F ₈ . For symmetrical wear of the jaws 17 and 18 due to the abrasion by workpieces in previous upsetting processes falls the longitudinal axis A of the workpiece 2 with the centering of Zentrierspanneinheit together (coaxiality), which is then completely unproblematic. For asymmetrical wear of the jaws 17 and 18 , namely greater wear on the lower jaw 18 , the longitudinal axis slips A There compared to the centering slightly by the difference of wear down, so there is a deviation from the coaxiality.

• Es wird zunächst nur eine Klemmelektrode, deren Aktuator mit einer Arretiereinheit versehen ist, beispielsweise die erste Klemmelektrode 5, mittels des, vorzugsweise hydraulischen, Aktuators 25 radial zur Längsachse A, hier von oben, gegen die Kontaktfläche 2c des Werkstücks 2 gefahren. Dabei wird ein nur ganz leichter oder geringer Anpressdruck eingestellt, um das Werkstück 2 nicht radial zu verschieben oder zu verbiegen, sondern in der von der zweiten Elektrodeneinheit 7 und 8 und deren Zentriereinheit 9a und 9b eingestellten vertikalen Lage seiner Längsachse A zu belassen. In dieser Position mit einseitig anliegender Klemmelektrode 5 wird nun der zugehörige Aktuator 25 mittels seiner Arretiereinheit mechanisch arretiert, so dass sich die Klemmbacke 15 der Klemmelektrode 5 nicht mehr radial nach außen bewegen kann.

In order to change the shape 28 but again a coaxiality in the first electrode unit with the now shifted workpiece axis A In the area of the second electrode unit and its centering clamping unit, the first electrode unit will now be in contact with the workpiece as follows in the next method step 2 accommodated:

• Initially, only a clamping electrode, the actuator of which is provided with a locking unit, for example the first clamping electrode 5 , by means of the, preferably hydraulic, actuator 25 radial to the longitudinal axis A , here from above, against the contact surface 2c of the workpiece 2 hazards. In this case, only a very slight or low contact pressure is set to the workpiece 2 not radially displace or bend, but in the of the second electrode unit 7 and 8th and their centering unit 9a and 9b adjusted vertical position of its longitudinal axis A to leave. In this position with one-sided clamping electrode 5 now becomes the associated actuator 25 mechanically locked by means of its locking, so that the jaw 15 the clamping electrode 5 can not move radially outward.

Now, by means of the associated, preferably hydraulic, actuator 29 the second clamping electrode 6 the first electrode unit with its jaw 16 against the associated contact surface 2c of the workpiece 2 driven, and indeed with a significantly higher clamping force or contact force F ₆ (or - pressure), so that the workpiece 2 between second jaw 16 and mechanically locked first jaw 15 is clamped and itself F ₅ = F ₆ established. Due to the mechanical locking or locking of only slightly to the workpiece 2 approached first clamping electrode 5 in interaction with the second hydraulically moved and tensioned second clamping electrode 6 are the first and second clamping electrodes 5 . 6 hydraulically decoupled. A radial displacement of the first and second clamping electrodes 5 and 6 due to balancing processes in the hydraulic system is therefore avoided. The workpiece 2 thus becomes of the first and second clamping electrodes 5 . 6 Reliable in the set during clamping (vertical) position of its longitudinal axis A held. Although the actuator 29 the second clamping electrode 6 has a locking unit, may possibly also the second clamping electrode 6 after the hydraulic clamping still be mechanically locked to relieve the hydraulic system.

Through this advantageous sequence of steps, the position of the longitudinal axis A of the workpiece 2 in the strain area 28 not disadvantageous by a stronger wear of the jaw 18 but concentricity or coaxiality is respected.

In the described embodiments according to the invention, the deformation range becomes 28 in a middle or inner area of the workpiece 2 at a distance from one end 22 and the support surface 2 B and also the end 27 and the support surface 2a produced by free-forming without die by means of electric diving. So you can speak of a mid-free diving.

There are also various modifications to the shown and described embodiments possible.

The compression device 1 is in the embodiments here horizontal compression device, ie with a horizontal feed direction V and longitudinal axis A , educated. However, the upsetting device can also be vertical or oblique with vertical or oblique feed direction with corresponding minor structural changes V be educated.

The self-supporting area of the workpieces 2 between compression body, for example 19 and the closest electrode unit 7 and 8th can also be supported and / or guided by not shown intermediate supports and / or guides.

The clamping electrodes 5 to 8th and / or their jaws 15 to 18 are advantageously cooled, for example by means of passed cooling water.

LIST OF REFERENCE NUMBERS

1

clincher

2

workpiece

2a

first support surface on the workpiece

2 B

second support surface on the workpiece

2c

first contact surface on the workpiece

2d

second contact surface on the workpiece

3

frame

3a, 3b

frame columns

4a, 4b

carrier plates

5

first clamping electrode

6

second clamping electrode

7

third clamping electrode

8th

fourth clamping electrode

9a

first centering clamping element

9b

second centering clamping element

10

support element

11

evasive body

12

dodge cylinder

13

bypass piston

14

spacer

15

first jaw

16

second jaw

17

third jaw

18

fourth jaw

19

compression body

20

drive cylinder

21

drive piston

22

first end section

23, 24

support surface

25

actuator

26

carriage

27

second end section

28

Deformation field

29

actuator

30

guide elements

40

setting device

110

supporting

111

free space

125

locking unit

140

supporting

190

supporting

A

Workpiece axis

I

heating

V

feed direction

L (t0), L (t1)

Distance or length of the workpiece

a (t0), a (t1)

axial distance of the electrodes

a _const

constant, axial distance

b ₀ , b ₁

first, second radial width

ΔL1, ΔL2

feed path

v1, v2

speed

F ₅ , F ₆ , F ₇ , F ₈

clamping force

Claims (10)

Stuffering device (1) for electro-upsetting, preferably elongated or rod-shaped, workpieces (2), comprising a) an upsetting unit (14, 19, 20, 21) for applying an upsetting force (FS) to a workpiece (2) between a first support surface (2). 2a) and one of the first support surface (2a) facing away from the second support surface (2b) of the workpiece (2) during an upsetting operation and b) a first electrode unit (5, 6) and a second electrode unit (7, 8) for electrically heating a between lying to them C) wherein the upsetting unit has a compression body (19) axially movable or moved in at least one feed direction (V) with at least one first support surface (190) for the first support surface (2a) on the workpiece (2) and an at least in the feed direction (V) movable or moving escape body (11, 14) with at least one second support surface (110) for the second support surface (2b) on the workpiece (2) and an adjusting device ( 40), which is in operative connection with the compression body (19) and the escape body (11), for setting an axial distance in the feed direction (V) between the support surfaces (190, 110) of compression body (19) and escape body (11 ), d) wherein the first electrode unit (5, 6) of the second support surface (110) to a constant at least during the upsetting axial distance (a _const ) is axially spaced from the feed direction (V) and is mitbewegbar with the escape body (11) of the compression unit and e) wherein the second electrode unit (7, 8) between the first electrode unit (5, 6) and the first support surface (190 ) is arranged on the compression body (19) and is arranged at least during the compression process at a fixed axial position. Compression device (1) after Claim 1 in which the first electrode unit has at least two clamping electrodes (5, 6) for clamping to first, preferably two diametrically and / or vertically opposite, contact surfaces (2c) of the workpiece (2) in electrically conductive contact and the second electrode unit at least two clamping electrodes ( 7, 8) for clamping to second, preferably two diametrically and / or horizontally opposite, contact surfaces (2d) of the workpiece (2) in electrically conductive contact and further preferably an electrical supply unit for applying an electrical heating current (I), preferably one low-frequency alternating electrical current, between the clamping electrodes (5, 6, 7, 8) of the two electrode units is provided, which flows through the contact surfaces (2c, 2d) through the deformation area (28) of the workpiece (2) and this heated to the forming temperature resistive , wherein preferably the adjusting device (40) for free-forming the workpiece s (2) in the deformation area (28), the axial distance between the support surfaces (190, 110) of compression body (19) and escape body (11) in response to the heating current (I). Compression device (1) after Claim 2 in which the first electrode unit for the first clamping electrode (5) and for the second clamping electrode (6), in particular for the clamping electrodes (5, 6) associated carrier carriage (26), respectively associated, in particular designed as a hydraulic piston actuators, actuators (25, 29 ) are provided for laterally or radially to the feed direction (V) directed movement of the clamping electrodes (5, 6) and for adjusting the pressure exerted on the clamping surfaces on the workpiece (2) clamping pressure, wherein at least one actuator (25, 29), in particular an actuator (25) for an upper clamping electrode (5), a mechanical locking unit (125) is assigned for locking the actuator (25, 29) and thus the associated clamping electrode (5 or 6) in its or their radial position. An upsetting device (1) according to any one of the preceding claims, wherein the second electrode unit is associated with a centering clamping unit comprising two centering clamping elements (9a, 9b) which are symmetrical about a centering axis via a synchronizing device which preferably passes through the workpiece (2) during the upsetting operation. extends, toward each other or away from each other and are preferably guided linearly against each other and / or driven by pressurized pistons, wherein on or on a first of the two Zentrierspannelemente (9a) a clamping electrode (7) of the second electrode unit and on or on a second of the two centering clamping elements (9b) or another clamping electrode (8) of the second electrode unit is fastened or held. A compression device (1) according to any one of the preceding claims, wherein the escape body (11) comprises a spacer (14) on which the at least one second support surface (110) is formed, the choice of the axial length of the spacer (14) or the use of spacers (14) of different axial length of the constant axial distance (a _const ) of the first electrode unit (5, 6) of the second support surface (110) is adjustable. Compressing device (1) according to one of the preceding claims, wherein the escape body (11) and / or the spacer (14) is at least partially electrically insulating and thereby flows with adjacent heating current (I) from any appreciable electric current. A process for the electrical dipping of, preferably elongated or rod-shaped, workpieces (2), during which during a compression process a) a workpiece (2) between a first support surface (2a) and a second support surface (2b) facing away from the first support surface (2a) an upsetting force (FS) is acted on and b) a form change region (28) of the workpiece (2) lying between the two support surfaces (2a, 2b) and spaced from both support surfaces (2a, 2b) by means of an electric current flowing through the deformation area (28) Heating current (I), by means of a first electrode unit (5, 6) and a second electrode unit (7, 8), at respective of the support surfaces (2a, 2b) spaced contact surfaces (2c, 2d) of the workpiece (2) in electrically conductive contact with the workpiece (2), is introduced, is heated to at least one forming temperature and is compressed by the simultaneous application of the compressive force in a free-forming process, ie without die, and by subsequent flow or tracking of material of the workpiece (2) in its shape or its Volume or its cross-section is increased, and wherein the second electrode unit (7, 8) between the first electrode unit (5, 6) and the first support surface (190) on the compression body (19) is arranged and at least during the compression process at a fixed axial position is arranged. Method according to Claim 7 in which in particular a compression device (1) according to one of Claims 1 to 6 is used, wherein a) one or the compression body (19) of one or the upsetting unit is brought with its at least one first support surface (190) in abutment with the first support surface (2a) on the workpiece (2) and one or the escape body (11, 14 ) is brought with its at least one second support surface (110) in abutment with the second support surface (2b) on the workpiece (2) and b) by means of one or the adjusting device (40), the axial distance in the feed direction (V) between the support surfaces (190, 110) of compression body (19) and the escape body (11) is reduced during the compression process, in particular by the compression body (19) in the feed direction (V) is moved at a greater speed than the escape body (11), whereby the compression force generated or is maintained, c) wherein the first electrode unit (5, 6) of the second support surface (110) by a predetermined during the upsetting constant axial distance (a _const ) axially opposite to the feed direction (V) is kept at a distance and with the escape body (11) is moved and d) wherein the workpiece (2) during the upsetting process by the second electrode unit, in particular their clamping electrodes (7, 8), via a e) wherein in particular the shape of the deformation region (28) is determined by the deformation temperature or by the heating current (I) between the electrode units through the deformation region (FIG. 28) on the one hand and by the temporal speed curves of the speeds of compression body (19) and escape body (11) on the other hand is controlled. Method according to Claim 7 or Claim 8 in which a) the workpiece (2) is inserted in a first method step at the beginning of an upsetting operation, in particular between the support surfaces (190, 110 or 190, 140) is clamped, wherein the two electrode units not in, in particular complete contact with the workpiece (2), b) in a second method step, the second electrode unit by means of the centering unit with the workpiece (2) in, in particular complete, contact, wherein at least two clamping electrodes (5, 6, 7, 8) of each electrode unit , in particular by means of associated Zentrierspannelemente (9a, 9b), symmetrically with respect to a centering or centering on the workpiece (2) to move and clamped to the contact surfaces (2c, 2d) in conductive contact with a predetermined clamping force, wherein in asymmetric wear of the clamping electrodes (5, 6, 7, 8), in particular due to the abrasion by slipping workpieces (2) in previously erf olgten upsetting operations, one, in particular parallel or axially to the feed direction (V) extending or arranged workpiece axis (A) of the workpiece (2) is shifted to the centering axis by an amount dependent on the amount of wear, c) in a third step, the first electrode unit in, especially complete, contact with the workpiece (2) is brought, Method according to Claim 9 in which in the third method step c1) initially only one or the first clamping electrode (5) of the first electrode unit, in particular by means of one or the, preferably hydraulic, actuator (25, 29) and / or in particular radially to the workpiece axis (A), against a Contact surface (2c) of the workpiece (2) is driven and / or applied under a low contact pressure, so that the workpiece (2) is not displaced or bent substantially radially, but substantially in the centered in the second step of the workpiece axis ( A) remains, and is then locked in this position, in particular by means of one or the locking unit (125) of the actuator (25) and by c2) one or the second clamping electrode (6) of the first electrode unit, in particular by means of one or the associated, preferably hydraulic, actuator (29) is moved against one or the associated contact surface (2c) of the workpiece (2), and then the workpiece (2 ) is clamped with a higher clamping pressure between the two clamping electrodes (5, 6).

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