Mechanism for closing electrodes

0001The present invention relates to a welding device having at least two welding electrodes. To change the width of a welding gap Welding gap, which the at least two mutually opposite substantially Welding electrodes defining between them, including the Welder a source of strength and a force of the power source transferring power transmission mechanism. From the welding electrodes is at least one electrode through a provided from the power source and by means of the transmission mechanism transmitted to her Force in the direction towards the other electrode and away from said movable.

0002Such a welding device is known from DE 197 55 166 A1. The welding apparatus shown there has as a power source an a Shaft rotating eccentric and a power transmission mechanism a compression spring is used as a welding gap-closing spring. The Closing spring is connected at one end to an eccentric cam on the lateral surface- applied to the plunger and at its other end to a a rotational axis swiveling Schweißelektrodenarm supported. To the Schweißelektrodenarm engages also a as weld gap-opening spring used other compression spring which at the Schweißelektrodenarm unloaded or lightly loaded closing spring in a direction in a Enlargement of the weld gap facing opening direction biases.

0003A disadvantage of this construction is that the eccentric stroke immediately the Schweißelektrodenarm and thus to the rigidly connected with this, Portable welding electrode is transmitted. This leads for joining parts a certain minimum size to satisfactory results. With miniaturization progresses the joint parts against external are Influences more and more sensitive. The pressure prevailing at the welding point Movement of the movable welding electrode is then the requirements the miniaturized joining part due to possible occurring Shocks and impacts can no longer cope.

0004Another critical point of the welding apparatus of the prior Technique is the influence of the friction to the movement of Schweißelektrodenarms, particularly in movements with a small stroke, such as those Settling of Schweißelektrodenarms during the melting of Welding projections represent at one of the assembly components, or both adherends.

0005It is therefore an object of the present invention, a welding device specify the type mentioned initially, in which the movement sequence the welding electrode at a welding gap reduction under possible carried low mechanical stress of the joining part, particularly in a phase in which a touching contact between the electrode and the is prepared adherend. It is mainly the increased sensitivity miniaturized assembly components considered to mechanical loads.

0006This object is according to the present task by a generic dissolved welding apparatus comprising at least one lever mechanism comprises, as the power transmission mechanism, said lever mechanism having a first linkage system, which with respect to a dormant parts of the welder fixed Anlenkort a frame rotation axis is rotatable and wherein the lever mechanism further comprises a having second link system which is applied to a first Anlenkort the first link system about a first axis of rotation rotatably hinged and rotatably on a second Anlenkort about a second pivot axis with the movable electrode is connected.

0007When the lever mechanism described above is not excluded, that besides the mentioned Anlenkorten more Anlenkorte available are. Rather, the description of the lever mechanism is to be understood in such a way that at least the mentioned Anlenkorte should be present.

0008Furthermore, does not mean "connected to the movable electrode" necessarily a direct articulation to the movable electrode. The rotatable connection can also be a mobile with the realized electrode connected motion-transmitting device Part be.

0009By the above arrangement of the steering systems can be achieved a rotational movement of the first Anlenkorts by an angular amount about the fixed Anlenkort around in a movement of the second with a Anlenkorts very small component of motion in Elektrodenschließ- and -öffnungsrichtung is stocky. Knocks and bumps on a at the joint arranged joining part can be avoided. The actual Reduction ratio varies in dependence on the position the first Anlenkortes. The motion reduction leads to a corresponding Power transmission, so that frictional resistances, the one Movement of Schweißelektrodenarms would preclude safe be overcome.

0010With welding standby position is a position of the electrodes designated, wherein by touching contact between conductive parts in Welding gap from a technical perspective a welding operation can be carried out, d. h. a position in which between the electrodes, a welding current can flow through the adherend therethrough.

0011Furthermore, by judicious choice of dimensions of the individual Handlebar systems a controlled and reproducible approach movement the electrodes toward each other in the sub-millimeter readily realizable.

0012In a structurally particularly simple embodiment, the lever mechanism a toggle mechanism, wherein the frame rotational axis, the first and second axis of rotation in pairs substantially parallel to each other. The substantially parallel arrangement of the Rotary axis alignment ensures easily calculable ratios as well as a lower operating wear and thus for a long life and a low-friction operation of the welding apparatus.

0013Basically, the second link system in the simplest case only consist of a single link. Preferably, the second However link system, a plurality of arms which are substantially a common first and have a common second axis of rotation and disposed in the direction of the second axis of rotation spaced from one another are. By the plurality of arm systems, on the one hand a redundancy achieved, so that the welding device also in the unlikely The event of breakage of a link, at least for emergency operation remains. Furthermore, this embodiment allows for an symmetrical force and movement initiation and sets the stage for a play-free movement of the movable welding electrode.

0014As well as the second link system can accordingly also the first Linkage system comprise a plurality of arms which are substantially having a common frame rotational axis and in the direction of Rack rotation axis are spaced from each other. To the to keep processing costs within limits, includes the second as the first linkage system each preferably two links.

0015The joining parts discussed herein is components with thickness dimensions in the range of hundredths or tenths of a millimeter. A for accurate positioning useful play as possible movement of movable welding electrode to the other electrode or from This can achieved by training off the second such Anlenkortes be that the second link system towards the electrode a in the direction of movement the electrode extending force and, at least temporarily, beyond towards the second rotational axis extending, today opposite forces are transferable.

0016Structurally, the opposing forces in a very simple Manner be caused by the fact that the second Anlenkort is designed such that on one side:, handlebar system side or the electrode side a protrusion with a conical mantle surface is provided, which with a correspondingly inclined, preferably a complementary-conical A boundary surface provided on the other side Coupling recess at least temporarily in abutting engagement stands. The opposing forces cause tension the at least one movable electrode with respect to the second link system, so that they are substantially free of side variations in Movement direction is displaced. The longer this stressed state maintained during displacement of the movable electrode it can be, the better in terms of generated weld. The so tight welding electrode due to the characterized essentially avoided page variations with great accuracy be disposed at the joint, which in turn to a improved dimensional accuracy of the welding result leads.

0017It is known that knee-joint lever with increasing motion reduction achieve a rising equally power transmission. In order arranged at the joint part to be joined from being damaged or even destruction by the occurring very high forces on the to protect electrode active surface, the coupling recess may be used as his long hole configured and arranged such that the longitudinal direction the elongated hole at a sweat preparing electrodes position substantially extends in the direction of movement of the movable electrode. At a such an arrangement allows the slot in the welding electrodes are preparing position ie resting the electrode active surface on the joining part, that no pressure forces of the lever system on the electrode and thus act on the joining part.

0018In addition, permitted such a long hole formed a low-friction Setting the at least one movable electrode during Welding, as effected by a melting of the component specifically or on the carrier object provided welding projections.

0019The at least one movable welding electrode, according to a Development of the invention for linear movement of the welder be arranged. However, it can also be made of the prior art proven way to a rotating bearing to an electrode axis of rotation be rotatably mounted, passing through a Schweißelektrodenarm is connected to the rotary bearing. By Schweißelektrodenarm is at sufficient Schweißelektrodenarmlänge and only little change of the welding gap a quasi-linear displacement of achieved movable electrode without a complicated linear guide is required. In this arrangement, the movable electrode at a Schweißelektrodenarm it is a low-friction operation particularly favorable when the second axis of rotation, preferably the first axis of rotation and the frame rotation axis, the electrode axis of rotation substantially is parallel.

0020There may be difficulties to Schweißelektrodenarm be arranged such that it, other parts of the device of the welding apparatus in particular, the transport device, does not interfere. A collision avoidance in the direction of the electrode axis of rotation offset arrangement the Schweißelektrodenarms may possibly result in an undesirable Distortion of the Schweißelektrodenarms about the longitudinal axis the Schweißelektrodenarms done. This distortion can be prevented when your Schweißelektrodenarm two toward the electrode axis of rotation with spaced apart carrier. Important Welding parts of the device, with which a collision is obviated shall be allowed, according to one embodiment of the invention between the be two carriers provided. For reasons symmetrical shear force and Introduction movement are the carriers of this entails regarding her mobile welding electrode preferably arranged symmetrically. Around to avoid a relative movement of the two carriers to each other may According to the invention both the carrier rotationally fixed to a common rotary shaft be connected.

0021A particularly for positionally accurate displacement of the welding electrode cheap, symmetrical as possible introduction of forces into the carrier can continue be effected in that each one link of the second link system to each a carrier is articulated pivotable about the second axis of rotation.

0022The power source of the welding apparatus, according to an advantageous Alternatively, the present invention, a double-acting power source be such that with it the welding electrodes to each other and each other can be moved away. Often described herein However welders part of a larger system, which clocked works, the clock of eccentric given as power sources becomes. Through this type cams can without undesirable complicated Measures such as the provision of engaging grooves, only forces in a Direction are transmitted. In such a case it is favorable if the welding device a force element, which movable the Electrode in a direction: welding gap width increase or Welding gap width reduction, applied force to the necessary provide power for a change in the welding gap width in this direction. To counter the impingement by the force element a Change the welding gap in the respective opposite To achieve direction, the force element is through the power source surmountable.

0023Since accompanying the motion reduction of the lever mechanism Power transmission is not to be used, the power source basically on the second link system for force and movement initiation attack. For ease of assembly of the power source However, at the welding apparatus are a force and movement initiation preferably by the power source in the first link system. Around all the gap-changing force attacks as close together provide what in regard to an interpretation of the system is advantageous to the strength element may also be on one of the link systems, due to the favorable movement conditions preferably the first link system, to transmit force attack.

0024A great spatial separation of force or movement in Introduction the first link system and force or movement from the first derivation in the second linkage system, according to one embodiment of the invention be achieved if the first link system at least one angle arm with two a predetermined angle enclosing legs , wherein the one leg a force introduction region for introducing by force of the power source as well as a site of action of the force element and wherein the second leg of the first Anlenkort for hinging the second link system is formed.

0025Since providing a as defined above oblong hole in sweat prepare State of the electrodes do not force the lever mechanism to the electrode can be transmitted, it is of a defined Pressing force of the electrode on the part to be joined advantageous when moving on Electrode, preferably an affiliated Schweißelektrodenarm, at least in the welding standby position in a Direction of a welding gap reduction acting force is applied. in the the simplest case, this force acting on the electrode gravity be. For this purpose, it is sufficient that at least a movable electrode to arrange such that its gravity towards a welding gap reduction acts. achieved a greater freedom of design however one then, when the welding device comprises a force device, which acting in the direction of the welding gap reduction in force the movable electrode, preferably on the Schweißelektrodenarm, exercises. In this case, an arbitrarily oriented arrangement of the electrode possible.

0026The present invention will hereinafter with reference to the accompanying Figures are explained in detail. It shows:<dl tsize="12"><dt>Fig. 1</dt><dd>a cross-sectional view of a welding apparatus of the invention with a transport device and with a Electrodes closing mechanism for defined lifting and lowering a movable welding electrode,</dd><dt>FIG. 2</dt><dd>a transport device and the electrode closing mechanism comprehensive enlarged section of FIG. 1,</dd><dt>Fig. 3</dt><dd>a sectional view taken along the line VV in Fig. 2,</dd><dt>Fig. 4</dt><dd>a sectional view taken along line VI-VI of Fig. 2,</dd><dt>Figure 5a -. 5d</dt><dd>a schematic representation of the different positions the welding electrodes, the lever mechanism and with this connected components during a closing movement the movable welding electrode.</dd></dl>

0027In Fig. 1, a welding system is generally designated 10. The welding system 10 comprises a contact band feeding unit 12, a contact part separation unit 14, a transport device 16 and a welding device 18th

0028A in Fig. 1 only, indicated by Strichlinierung contact band 20 runs in the drawing plane of Fig. 1 of the contact strip feed unit 12 clocked driven to the contact part separation unit 14. In the contact part separation unit 14 are sheared from the contact strip Contact portions of defined length separated. These contact parts are in the Transporter 1 6 of an assembly 22 comprising a holding and received a release device in a fixture-receiving position and transported to a holding device-delivery position.

0029The welding device 18 includes a device with respect to a frame the welder stationary lower welding electrode 24 and one to an electrode axis of rotation E rotatable movable welding electrode 26. The movable welding electrode 26 is a Schweißelektrodenarm 28 connected to the rotary mounting about the electrode axis of rotation E and in the direction of the double arrow K to the electrode 24 to and from this moved away. The Schweißelektrodenarm 28 only in sections, partly by Strichlinierung represented.

0030The clock for the contact strip-feed unit 12 and for lifting and Lowering the movable welding electrode 26 is indicated by a first eccentric cam 30 to a spring force of the eccentric cam-lateral surface 30a adjacent the first plunger 32 transmitted.

0031Likewise, a stroke for moving the transport device 16 is a second eccentric cam 34 to a spring force of the eccentric cam-lateral surface 34a adjacent second plunger 36 transmitted. In the second plunger 36, the short leg of an L-shaped lever 38a 38 rotatably mounted, the long limb 38b a sliding movement the assembly 22 in upward and downward movement of the second plunger 36 causes. The assembly 22 or rotatably connected to her component comprises a tooth pitch, which during the displacement movement on a rack rolls, so that the assembly 22 a combined performs sliding and rotational movement. This allows overcoming large distances between holder-receiving position and retaining device-delivery position. The kinematics of the assembly 22 in the transition from the holding device accommodating position to the holding device-delivery position and vice versa is described in DE 197 55 166 A1, the disclosure of should be part of the present application, described in detail.

0032From the first plunger 32 is a plate nut 40 moving on a first linkage system 42 transferred. is from the first link system 42 via a second linkage system 44 for the movement Schweißelektrodenarm 28 transferred.

0033For a detailed description of FIG. 2 below. First However, the transport device 16 for feeding the welding device 18 with components to be joined (adherends) described.

0034One longitudinal end of the long arm 38b of the L-shaped lever 38 is rotatably received in a sliding element 46, which along a parallel to the plane of FIG. 2 arranged guide rod 48 is slidably disposed. About a connecting pin 50 and a Connecting rivet 52 which rotatably connected to the rotation in the sliding element 46 mounted connecting pin 50 is connected, the assembly are 22 and a Abwälzteil 54 connected to the displacement element 46th The assembly 22 comprising the holding device 56 and the Release means 58, and 54 are Abwälzteil for movement connected with each other.

0035In FIG. 2, the assembly 22, the Abwälzteil 54 and the displacement element 46 in solid lines at the left edge of the transport device 16 represented in the retainer-dispensing position. In contrast, the Holding means 56 'and the assembly 22' together with the Abwälzteil 54 'dashed in the retainer-receiving position shown in which from the retaining means 56, a joining part for transport into the Retaining device-delivery position is taken.

0036To overcome larger distances of the transition from the retainer-dispensing position occurs in the retainer-receiving position and reversed as follows:

0037Starting from the position shown in Fig. 2 by the solid lines Retaining device-delivery position is by depressing the plunger 36 the L-shaped lever by an angle β rotated counterclockwise. From the longitudinal end of the long leg 38b, the displacement element is 46 along the guide rod 48 taken to the right. The Abwälzteil 54, at the of the holding device 56 pioneering Longitudinal end 54a of a tooth pitch circle is formed, is first linearly shifted to the right, until the teeth engage a in FIG. 2 rack not shown passes. From manufacturing the gearing contact there is a shifting movement of the assembly 22 and the Abwälzteils 54 together with the slide member 46, of a Pivoting movement through 180 ° about the central axis 50a of the connecting bolt superimposed 50 around. After rotation by 180 ° enters the Teeth on Abwälzteil 54 out of engagement with the rack, whereupon the holding means 56 and with this the release device 58, the Abwälzteil 54 and the displacement member 46 is a linear movement in the Retainer-receiving position run. The transport movement of the Component, that is, the movement of the holding device 56 from the holding device accommodating position following in the retaining device-delivery position the sequence in reverse order.

0038As shown in Fig. 2, the assembly 22 further comprises a biasing compression spring 60 which the holding device 56 with respect to the release device 58 biases in a position in which the release device 58 is withdrawn with respect to the holding device 56th

0039Further, in Fig. 2, a lever mechanism 41 for raising and lowering the Schweißelektrodenarms 28 shown. The Schweißelektrodenarm 28 itself is not shown in Fig. 2. As is apparent from Fig. 1, acting through the plate nut 40 a clamping force S on a roller 64, which rotatably disposed on a first leg 42a of the first link system 42 is. The first leg 42a acts beyond the opening force O in the opposite direction. The opening force is O produced by pressing together the welding gap-opening spring 66th The welding gap-opening spring 66 is in its spring rate such chosen such that it can raise the Schweißelektrodenarm 28 but by the first eccentric cam 30 is compressible.

0040The first link system about a fixed or transport device fixed to the frame Rack rotation axis G mounted on a fixed Anlenkort 68 am Device frame articulated.

0041On longitudinal end of a second leg 42b, which forms an angle y with includes the first arm 42a, is at a first Anlenkort 70 to a first rotation axis H rotate the second linkage mechanism 44 is articulated.

0042At the first Anlenkort 70 opposite longitudinal end of the second linkage system 44 is at a second Anlenkort 72, the second Link system 44um a second rotation axis rotatable with the J in Fig. 2 not shown movable electrode 62. On the second Anlenkort 72 a slot 74 is formed in the second linkage mechanism 44, is on which received below illustrative. Alternatively, the its slot 74 also formed at Schweißelektrodenarm 28, at wherein the second linkage system 44 directly to the second Anlenkort 72 is articulated.

0043In Fig. 3 is a section along the line VV in Fig. 2 is shown. FIG. 5 is both the weld gap-opening spring 66 and its spring abutment and the first and second linkage system 42 and 44 cut shown.

0044The first linkage mechanism 42 comprises two arms 42₁ and 42₂, Which are connected by a common traverse 98th At the Traverse 98 is rotatably supported the role 64th

0045On mounting location 70, the handlebars 42₁ and 42₂ the first link system 42 about the first axis of rotation H rotatable with the second link system 44..

0046The second linkage system 44 also includes a first link 44₁and a second link 44₂, Here, the first link 44₁ the second Link system to the handlebars 42₁ the first system of links 42 hinged continue to the second link 44₂ of the second link system to the handlebar 42₂ the first system of links 42 hinged. The rigid coupling the handlebar 42₁ and 42₂ have the common Traverse 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 takes place by bolts 100, which between relative rotation the first and second linkage system permit.

0047The Schweißelektrodenarm 28 is formed in the example shown here by two substantially mutually parallel carrier 28₁ and 28₂Which is connected to a common non-illustrated rotary shaft are and without the possibility of relative rotation to each other about the electrode axis of rotation E rotate. In through holes 102₁ and 102₂ in the carriers 28₁ and 28₂ are the shafts of cone head rivets 104 added. The conical head 106 of the cone-head rivet 104 has a frustoconical head, which in the long hole 74 of the second Link system 44 hineinerstreckt. The slots are also with in subscripts to the assignment to the respective Links of the second linkage system 44 to identify. The slots 74₁ and 74₂ the second link system 44 are in accordance with the Cone angle of the cone head 106 inclined side surfaces 74b₁ and 74b₂ , on which the lateral surface of the cone head 106 abuts. By this constructional design it is achieved that when the carrier 28₁ and 28₂ of the swing arm 28 via the bevel heads 106 on the inclined Side surfaces 74b₁ and 74b₂ rest of the elongated holes 74, 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 28₂is transmitted, so that the carrier 28₁ and 28₂ under the force be apart pushed and clamped, which is a substantially backlash displacing the carrier allows. This allows a very accurate Positioning of the welding electrode.

0048In FIG. 4 is a section along the line VI-VI in Fig. 2 is shown. there interested essentially only the force applied to the carrier 28₁ and 28₂ by welding gap-closing springs 108₁ and 108₂, From this weld gap-closing springs 108₁ and 108₂ exerts any force Z₁ or Z₂ to their respective associated support 28₁ or 28₂ out of what a defined closing force in the welding position of the welding device ready guaranteed.

0049In the figures 5a-5d schematically simplifies the trajectory the lever mechanism 41, the electrodes 24 and 26 and associated Parts shown. The movement of the lever mechanism 41 and of the pivot arm 28 is shown in Figures 5a to 5d for better perception represented oversubscribed.

0050In Fig. 5a, the welding device 18 is open, ie with great welding gap shown. In welding gap 25 a component 84 is arranged.

0051By rotating the first eccentric cam 30 will be the first leg 42a of the first link system 42 against the biasing force of the welding gap-opening spring 66 in Fig. 7b pressed down, resulting in a to the frame rotation axis G in the rotation of the first link system 42 Clockwise leads. The first Anlenkort 70 also pivots clockwise to the frame rotation axis G, which under the action Welding gap-closing spring 108 to an extension of the lever mechanism 41 leads (see Fig. 5b). The pressing force of the welding gap-closing pressure spring 108 causes the Kegelkopfniet 104 at slot base 74a abuts.

0052In Fig. 5c is a position is reached in which the electrode active surface 26a rests on the member 84, so that a further closing of the welding gap 25 is mechanically restricted by the part 84th The welding gap-closing pressure spring 108 still causes a concern of Kegelkopfniets 104 74a on slot base.

0053In Fig. 5D, the welding device 18 is in a fully welded prepare Position shown. The lever mechanism 41 is in a stretched State, due to the obstruction of movement in the closing direction the Schweißelektrodenarms 28 caused by the component 84 that the Kegelkopfniet 104 no longer rests on the slot root 74a and in the direction of movement the electrode 26 from the lever mechanism 41, no force on the Schweißelektrodenarm 28 can be transmitted. Since the force of Welding gap-opening spring 66 through the first eccentric cam 30 and the plate nut 40 is overcome, alone determines the welding gap-closing pressure spring 108, to the component 84 through the movable electrode 26 applied force. This design of the fully welded ready Position has the further advantage that a low-friction setting the Schweißelektrodenarms 28 is possible during welding. For if the Component 84 provided with welding projections, which during a welding operation to melt, so is due to the between the Kegelkopfniet 104 and the long hole base 74a existing game Put a the Schweißelektrodenarms 28 possible so that the contact between the Welding electrode 26 and the component 84 is not interrupted. this makes possible a defined until the end of the welding process contact transition.

0054If an arrangement in the present application, or a relationship is described between components with "substantially", this shall express that a deviation within the standard production tolerances should be allowed.