Mechanism for closing electrodes

p0001The present invention relates to a welding apparatus according to the preamble of claim 1st

p0002A generic welding device is known from <patcit id="pcit0001" dnum="US4933531A"><text>US-A-4,933,531</text></patcit> known. In this known welding device comprises a movable welding electrode via a scissor mechanism and subsequent further link is connected to a device frame. The rack near endpoints of scissor mechanism can be displaced by a spindle drive. In addition, the entire, the scissor mechanism enclosing link mechanism can be rotated to move the welding electrode to a welding plane orthogonal to the axis of rotation substantially.

p0003It is therefore an object of the present invention to provide a welding device of the aforementioned kind in which the movement of the welding electrodes is performed at a welding gap reduction under as low mechanical stress of the joining part, in particular in a phase in which produced a touching contact between the electrode and the part to be joined becomes. In particular, the increased sensitivity of miniaturized parts to be joined must be considered to mechanical loads.

p0004This object is achieved according to the present task by a welding device having all features of claim 1. at least one embodiment of the invention a welding device comprises a lever mechanism as the power transmission mechanism, wherein the lever mechanism has a first link system which is rotatably mounted on a relative static parts of the welding apparatus fixed Anlenkort about a frame rotation axis, and wherein the lever mechanism further comprises a second link system which is rotatably articulated at a first Anlenkort on the first link system about a first axis of rotation and connected at a second Anlenkort about a second axis of rotation with the movable electrode.

p0005Here, the second link system comprises a plurality of links, which are substantially a common first and a common second axis of rotation and are arranged in the direction of the second axis of rotation at a distance from each other. By the plurality of arm systems, a redundancy is achieved on the one hand, so that the welding device remains at least for emergency operation even in the unlikely event of breakage of a link. Furthermore, this embodiment allows a favorable symmetrical force and movement initiation and sets the stage for a play-free movement of the movable welding electrode.

p0006When the lever mechanism described above is not excluded that in addition to the mentioned Anlenkorten more Anlenkorte exist. Rather, the description of the lever mechanism is to be understood such that at least the mentioned Anlenkorte should be present.

p0007Further, "connected with the movable electrode" is not necessarily a direct articulation to the movable electrode. The rotatable connection can also be implemented via an associate with the movable electrode movement transmitting device part.

p0008By the above arrangement of the steering systems can be achieved by a rotation of the first Anlenkorts by an angle to the fixed Anlenkort around is stocky in a movement of the second Anlenkorts with a very small component of motion in Elektrodenschließ- and -öffnungsrichtung. Knocks and bumps on a disposed at the joint joining part can be avoided. The actual reduction ratio varies in dependence on the position of first Anlenkortes. The motion reduction leads to a corresponding power transmission so that frictional resistance which would preclude movement of Schweißelektrodenarms be reliably overcome.

p0009With "welding standby position" is a position of the electrodes designated in which a welding operation can be performed by touching contact between conductive parts in the welding gap from a technical perspective, ie a position in which between the electrodes, a welding current through the joining part can flow therethrough.

p0010In addition, can be realized by judicious choice of dimensions of each handlebar systems a controlled and reproducible approach movement of the electrodes toward each other in the sub-millimeter readily.

p0011In a structurally particularly simple embodiment of the lever mechanism is a knee lever mechanism in which the frame rotation axis, the first and second axis of rotation in pairs in each case lie essentially parallel to each other. The substantially parallel arrangement of the axes of rotation to one another ensures easily calculable ratios as well as a lower operating wear and thus a long service life and a low-friction operation of the welder.

p0012As well as the second link system can also be the first link system comprises a plurality of arms, which essentially have a common frame rotational axis and are arranged in the direction of the rack axis of rotation spaced from one another. To keep the processing effort within limits, the second as the first link system each preferably comprises two links.

p0013The joining parts discussed herein is components with thicknesses in the range of hundredths or tenths of a millimeter. A for accurate positioning useful play as possible movement of the movable welding electrode to the other electrode or away can be achieved by forming the second Anlenkortes such that the second link system towards the electrode extending in the direction of movement of the electrode force and, at least temporarily , beyond towards the second rotational axis extending, opposing forces can be transmitted.

p0014Structurally can be caused by the opposing forces in a very simple manner that the second Anlenkort is designed such that on one side: a projection is provided with a conical lateral surface handlebar system side or the electrode side, which is complementary with a correspondingly inclined, preferably a -konischen boundary surface a provided on the other side coupling recess at least temporarily is in abutting engagement. The opposing forces cause a strain of at least one movable electrode with respect to the second link system, so that it is free of movable side deviations in the direction of movement substantially. it is the longer this stress state can be maintained during a displacement of the movable electrode, the more favorable as regards the achieved weld. The so tight welding electrode can be arranged due to the thereby substantially avoided page variations with great accuracy at the joint, which in turn leads to an improved dimensional accuracy of the welding result.

p0015It is known that the knee lever reach a rising equally power transmission with increasing movement speed reduction. To protect arranged at the joint part to be joined prior to damage or even destruction by the occurring high forces on the electrode active surface, the coupling recess may be formed as an elongated hole and arranged such that the longitudinal direction of the elongated hole in a welding prepare electrode position substantially extends in the direction of movement of the movable electrode. In such an arrangement the slot in the welding electrodes ready position, ie resting the electrode active surface on the joining element allows no pressure forces act on the lever system to the electrode and thus the bonded parts.

p0016In addition, permitted such a long hole formed a low-friction setting the at least one movable electrode during welding, such as caused by a melting of specially on the component or on the carrier object provided welding projections.

p0017The at least one movable welding electrode can be arranged in accordance with an embodiment of the invention for linear movement of the welder. However, it can be rotatably supported in the best of the prior art manner on a pivot point to an electrode axis of rotation, it is connected by a Schweißelektrodenarm with the pivot point. By Schweißelektrodenarm a quasi-linear displacement of the movable electrode is achieved in adequate Schweißelektrodenarmlänge and only a slight change of the welding gap, without requiring a complicated linear guide is required. In this arrangement, the movable electrode at a Schweißelektrodenarm it is particularly favorable for a low-friction operation, when the second axis of rotation, preferably also the first axis of rotation and the frame rotation axis, the electrode axis of rotation is substantially parallel.

p0018There may be difficulties to arrange the Schweißelektrodenarm such that it does not interfere with other parts of the device of the welding device, in particular the transport device. An offset for collision avoidance in the direction of the electrode axis of rotation of the assembly Schweißelektrodenarms can occur to an undesirable torsion of the Schweißelektrodenarms about the longitudinal axis of the Schweißelektrodenarms under certain circumstances. This distortion can be prevented when the Schweißelektrodenarm having two electrodes in the direction of the rotation axis with spaced apart carrier. Important welder parts with which a collision is to be avoided, can be provided according to an embodiment of the invention between the two carriers. For reasons symmetrical shear force and movement initiation, the carriers are arranged symmetrically with respect to the preferably connected with their mobile welding electrode. To prevent relative movement of the two support each other, can inventively be rotatably connected both carriers with a common rotary shaft.

p0019A particularly favorable for positionally accurate displacement of the welding electrode, as symmetrical as possible introduction of forces into the carrier can continue to take place in that each one link of the second link system is pivoted to a respective carrier about the second axis of rotation.

p0020can be moved, the power source of the welding device may be according to an advantageous alternative of the present invention, a double-acting power source, so that with it the welding electrodes together and apart. Often, however, the welding apparatus described herein are part of a larger system, which operates clocked with the clock of eccentric cam is defined as power sources. By such cam only forces can be transmitted in one direction without undesirable complicated measures, such as the provision of engaging grooves. In such a case it is advantageous if the welding device comprises a force element in one direction, the movable electrode: welding gap width increase or welding gap width reduction, applied force to provide the necessary power for a change in the welding gap width in this direction. In order to achieve against the bias by the power element is a change in the weld gap in the respective opposite direction, the force element can be overcome by the power source.

p0021As an accompanying the movement of the lever mechanism reduction power transmission is not to be used, the power source can basically attack on the second link system for force and movement initiation. For ease of assembly of the power source to the welding device, however, a force and movement initiation are preferred by the power source in the first link system. To all the gap-changing force attacks nearly as possible to provide, which is also advantageous in view of a design of the system, the force element can also be in one of the handlebar systems, due to the favorable movement conditions preferably, a force-transmitting attack on the first link system.

p0022A great spatial separation of force or movement initiation in the first link system and force or movement deriving from the first to the second linkage system can be achieved according to an embodiment of the invention, when the first link system comprises at least one angle arm with two a predetermined angle enclosing legs where having a leg a force application area for the introduction of force of the power source as well as a site of action of the force element and being formed on the second leg of the first Anlenkort for the articulation of the second link system.

p0023Since provision of a as defined above, the elongated hole in the weld-ready state of the electrodes no force from the lever mechanism can be transmitted to the electrode, it is to ensure a defined pressing force of the electrode to the adherend advantageous if connected to the movable electrode, preferably on one of their Schweißelektrodenarm, at least in the welding standby position acting in the direction of a welding gap reduction force is applied. In the simplest case, this force may be the force acting on the electrode gravity. For this purpose, it is sufficient that at least one movable electrode to be arranged such that its gravity acts in the direction of a welding gap reduction. A greater freedom of design is achieved, however, when the welding device comprises a force device, which on the Schweißelektrodenarm, exerts a force acting in the direction of the welding gap reduction force to the movable electrode, preferably. In this case, an arbitrarily oriented arrangement of the electrode is possible.

p0024The present invention will be described in greater detail below with reference to the accompanying figures. It shows:<dl id="dl0001"><dt>Fig. 1</dt><dd>a cross-sectional view of a welding apparatus of the invention with a transport device and having an electrode for defined locking mechanism lifting and lowering a movable welding electrode,</dd><dt>FIG. 2</dt><dd>a transport device and the electrode closing mechanism comprising enlarged section of <figref idrefs="f0001">Fig. 1</figref>.</dd><dt>Fig. 3</dt><dd>a sectional view taken along line VV in <figref idrefs="f0002">FIG. 2</figref>.</dd><dt>Fig. 4</dt><dd>a sectional view taken along line VI-VI of <figref idrefs="f0002">FIG. 2</figref>.</dd><dt>Figure 5a -. 5d</dt><dd>a schematic representation of the different positions of the welding electrodes, the lever mechanism and the components associated with this during a closing movement of the movable welding electrode.</dd></dl>

p0025In <figref idrefs="f0001">Fig. 1</figref> is generally designated by 10 is a welding system. The welding system 10 includes a contact strip-feed unit 12, a contact part separation unit 14, a transport device 16 and a welding device 18th

p0026one in <figref idrefs="f0001">Fig. 1</figref> runs only by Strichlinierung, indicated contact band 20 in the plane of projection <figref idrefs="f0001">Fig. 1</figref> clocked by the contact strip-feed unit 12 is driven to the contact part separation unit 14. In the contact part separation unit 14 are separated by shearing-defined contact band contact part length. These contact parts are added to the transport device 1 6 of an assembly 22 comprising a holding and release means in a holder-receiving position and transported to a holding device-delivery position.

p0027The welding apparatus 18 comprises a relative to a device frame of the welding device stationary lower welding electrode 24 and an electrode axis of rotation E rotatable movable welding electrode 26, the movable welding electrode 26 is connected via a Schweißelektrodenarm 28 with the rotary mounting about the electrode axis of rotation E and in the direction of double arrow K to the movable electrode 24 to and away from it. The Schweißelektrodenarm 28 only in sections, partly represented by Strichlinierung.

p0028The clock for the contact strip-feed unit 12 and the lifting and lowering of the movable welding electrode 26 is transferred to an adjacent 30a by spring force of the eccentric cam-lateral surface first plunger 32 via a first eccentric cam indicated 30th

p0029Likewise, a timing for moving the transport device 16 is transferred to a fitting 34a by spring force of the eccentric cam-lateral surface of the second ram 36 via a second eccentric cam 34th In the second plunger 36 of the short leg is rotatably mounted 38a of an L-shaped lever 38, the long limb 38b causes a sliding movement of the assembly 22 in up and down movement of the second plunger 36th The module 22 or a non-rotatably connected with their component comprises a tooth pitch circle that rolls off during the displacement movement on a rack so that the assembly 22 executes a combined sliding and rotational movement. This allows overcoming great distances between holder-receiving position and retaining device-delivery position. The kinematics of the assembly 22 at the transition from the retainer-receiving position to the holding device-delivery position and vice versa is in the<patcit id="pcit0002" dnum="DE19755166A1"><text>DE 197 55 166 A1</text></patcit>, The disclosure should be part of the present application, described in detail.

p0030From the first ram 32 40 movement is transmitted to a first link system 42 via a plate nut. From the first linkage mechanism 42, the movement is transmitted to Schweißelektrodenarm 28 via a second linkage system 44th

p0031For a detailed description of <figref idrefs="f0002">FIG. 2</figref> refer to. First, however, the transport device 16 is described for feeding of the welding device 18 with components to be joined (adherands).

p0032One longitudinal end of the long leg 38b of the L-shaped lever 38 is rotatably received in a sliding element 46, which along a parallel to the plane of <figref idrefs="f0002">FIG. 2</figref> arranged guide rod 48 is slidably disposed. Via a connecting bolt 50, and a connecting rivet 52, which is rotatably connected with the rotatably mounted in the slide member 46 connecting bolts 50, the assembly 22 and a Abwälzteil 54 are connected to the displacement element 46th The assembly 22 comprising the holding means 56 and release means 58, and the Abwälzteil 54 are interconnected for joint movement.

p0033In <figref idrefs="f0002">FIG. 2</figref> 46 is shown in solid lines at the left edge of the transport device 16 in the holding device-delivery position, the assembly 22, the Abwälzteil 54 and the displacement member. In contrast, the holding device 56 'or the assembly 22' together with the Abwälzteil 54 'in dashed lines shown in the holding device accommodating position in which the holding means 56, a joining member is received for transport into the holding device-delivery position.

p0034To overcome larger distances of the transition from the retaining device-delivery position in the retainer-receiving position and vice versa takes place as follows:

p0035Based on the in <figref idrefs="f0002">FIG. 2</figref> with solid lines shown holding device-delivery position is by depressing the plunger 36 of the L-shaped lever by an angle β rotated counterclockwise. From the longitudinal end of the long leg 38b, the displacement element 46 along the guide rod 48 to the right taken. The Abwälzteil 54, at the groundbreaking of the holding device 56 longitudinal end 54a, a tooth pitch is formed, is first moved linearly to the right, until the teeth engage a in<figref idrefs="f0002">FIG. 2</figref> Rack not shown passes. From manufacture of the toothed engagement of a sliding movement of the assembly 22 and the Abwälzteils 54 takes place together with the sliding member 46, which is superimposed by 180 ° about the central axis 50a of the connecting bolt 50 around a pivoting movement. After rotation by 180 °, the toothing reaches the Abwälzteil 54 out of engagement with the rack, whereupon the holding device to execute 56, and with this the release device 58, the Abwälzteil 54 and the displacement member 46 is a linear movement in the holder-receiving position. The transport movement of the component, ie, the movement of the holding device 56 from the holding device accommodating position in the holding device-delivery position following the sequence in reverse order.

p0036As in <figref idrefs="f0002">FIG. 2</figref> As shown, the assembly 22 further comprises a biasing compression spring 60 which biases the holding means 56 relative to the releasing means 58 in a position in which the releasing means 58 is withdrawn with respect to the holding means 56th

p0037Furthermore, in <figref idrefs="f0002">FIG. 2</figref> a lever mechanism 41 is shown for lifting and lowering the Schweißelektrodenarms 28th The Schweißelektrodenarm 28 itself is in<figref idrefs="f0002">FIG. 2</figref> Not shown. As from<figref idrefs="f0001">Fig. 1</figref> shows acts through the plate nut 40 a closing force S on a roller 64 which is rotatably disposed at a first leg 42a of the first link system 42nd On the first leg 42a, the opening force O in the opposite direction acts beyond. The opening force O is generated by compressing the weld gap-opening spring 66. The welding gap-opening spring 66 is selected in its spring rate such that it can raise the Schweißelektrodenarm 28, but can be compressed by the first eccentric 30th

p0038The first rod system is hinged to a stationary or transport device frame Fixed Rack rotation axis G mounted on a fixed Anlenkort 68 at the device frame.

p0039On longitudinal end of a second leg 42b, which angle a <i>y</i> includes to the first leg 42a, is rotatably hinged at a first Anlenkort 70 about a first axis of rotation H the second link system 44th

p0040At the end opposite the first Anlenkort 70 longitudinal end of the second link system 44, the second link system 44um a second rotational axis J is at a second Anlenkort 72 rotatable with the in <figref idrefs="f0002">FIG. 2</figref> not shown movable electrode 62. On the second Anlenkort 72 a slot 74 is formed in the second link system 44, on which received below illustrative. Alternatively, the elongated hole 74 also be formed on the Schweißelektrodenarm 28, where the second linkage mechanism 44 is at the second Anlenkort 72 hinged directly.

p0041In <figref idrefs="f0003">Fig. 3</figref> is a section along the line VV in <figref idrefs="f0002">FIG. 2</figref> shown. In<figref idrefs="f0005 f0006">Fig. 5</figref> 42 and 44, shown in section, both the welding gap-opening pressure spring 66 and its spring abutment and the first and second link system.

p0042The first linkage mechanism 42 comprises two arms 42₁ and 42₂, Which are interconnected via a common crossmember 98th At the Traverse 98 the roller is rotatably supported 64.

p0043On mounting location 70, the handlebars 42₁ and 42₂ the first system of links 42 pivotally connected to the first rotational axis H to the second link system 44th

p0044The second linkage system 44 also includes a first link 44₁ and a second link 44₂, Here, the first link 44₁ the second link system to the handlebars 42₁ the first system of links 42 hinged, is still the second link 44₂ the second link system to the handlebars 42₂ the first system of links 42 hinged. The rigid coupling of the handlebar 42₁ and 42₂ with the common crossmember 98, both first articulation points 70₁ and 70₂ a common first axis of rotation H on. The articulation of the second Lenkersystsems 44 on the first link system 42 is accomplished by bolts 100 which allow relative rotation between the first and second link system.

p0045The Schweißelektrodenarm 28 is in the example shown here, formed by two substantially parallel extending support 28₁ and 28₂Which are connected to a common, not shown rotary shaft and rotating without the possibility of relative rotation to one another about the electrode axis of rotation E. In through holes 102₁ and 102₂ in the carriers 28₁ and 28₂ the shanks of cone head rivets 104 are received. The conical head 106 of the cone-head rivet 104 has a tapered head which extends into the slot 74 of the second link system 44th The slots are also marked with subscripts to indicate the assignment to the respective links of the second linkage system 44th The slots 74₁ and 74₂ the second link system 44 are corresponding to the cone angle of the cone head 74b 106 inclined side surfaces₁ and 74b₂ , on which the lateral surface of the cone head 106 abuts. Due to this design it is achieved that when the carrier 28₁ and 28₂ the swing arm 28 on the cone heads 106 to the inclined side surfaces 74b₁ and 74b₂ the oblong holes 74 lie, not only a force in the direction of movement of the welding electrode 26 but also a force in the direction of arrows B₁ and B₂ on the respective carrier 28₁ and 28₂ is transmitted, so that the carrier 28₁ and 28₂ are pushed away and braced apart under the force, which permits an essentially play-free displacement of the carrier. This allows a very accurate positioning of the welding electrode.

p0046In <figref idrefs="f0004">Fig. 4</figref> is a section along the line VI-VI in <figref idrefs="f0002">FIG. 2</figref> shown. It essentially interested only the application of force to the carrier 28₁ and 28₂ by welding gap-closing springs 108₁ and 108₂, Of these welding gap-closing springs 108₁ and 108₂ exerts any force Z₁ or Z₂ to their respective associated support 28₁ or 28₂ from what ensures a defined closing force in the welding position of the welding device prepare.

p0047In the <figref idrefs="f0005 f0006">Figures 5a to 5d</figref> is a schematically simplified representation of the movement of the lever mechanism 41, the electrodes 24 and 26 and associated parts shown. The movement of the lever mechanism 41 and the swing arm 28 is in the<figref idrefs="f0005 f0006">Figures 5a to 5d</figref> illustrated for better perception oversubscribed.

p0048In <figref idrefs="f0005">Fig. 5a</figref> 18 is open, that is represented with great welding gap width, the welding device. In welding gap 25 a component 84 is arranged.

p0049By rotation of the first eccentric cam 30 of the first leg is now pressed 42a of the first link system 42 against the biasing force of the welding gap-opening pressure spring 66 in Fig. 7b downwards, which results in a rotation of the first link system 42 about the frame rotation axis G in the clockwise direction. The first Anlenkort 70 also pivots clockwise about the frame rotation axis G, causing under the action of the welding gap-closing pressure spring 108 to a stretching of the lever mechanism 41 (see<figref idrefs="f0005">Fig. 5b</figref>). The pressing force of the welding gap-closing spring 108 causes the Kegelkopfniet 104 abuts the slot root 74a.

p0050In <figref idrefs="f0006">Fig. 5c</figref> If the position is in which the electrode active surface 26a rests on the member 84, so that a further closing of the welding gap 25 by the component 84 is mechanically inhibited. The welding gap-closing spring 108 still causes for concern 74a of Kegelkopfniets 104 at slot base.

p0051In <figref idrefs="f0006">Fig. 5d</figref> 18 is shown in a fully welded ready position the welder. The lever mechanism 41 is in a stretched condition, which causes due to the obstruction of movement in the closing direction of Schweißelektrodenarms 28 through the component 84 that the Kegelkopfniet 104 no longer rests on the slot root 74a and transmitted in the direction of movement of the electrode 26 from the lever mechanism 41 no force on the Schweißelektrodenarm 28 can be. Since the force of the welding gap-opening spring 66 is overcome by the first eccentric cam plate 30 and the nut 40 alone the welding gap-closing pressure spring 108 determines the force exerted by the member 84, the movable electrode 26 force. This design of the fully welded ready position has the further advantage that a low-friction setting the Schweißelektrodenarms 28 during welding is possible. Indeed, if the component 84 provided with welding projections, which are intended to melt during a welding operation, so a set of Schweißelektrodenarms 28 is possible due to the presence between the Kegelkopfniet 104 and the slot base 74 a game, so that the contact between the welding electrode 26 and the component 84 is not interrupted. This allows a defined until the end of the welding process contact transition.

p0052If in the present application, an arrangement or a relationship between components is described as "substantially", this shall express that a deviation in the normal course of production tolerances should be allowed.