GB2134023A - Welding contacts to a carrier - Google Patents

Abstract

In a welding unit for welding preferably profiled contacts 19 to a carrier 20, individualized contacts are pushed through a correspondingly profiled guide tunnel to a position between a welding electrode 2 and the carrier 20. The guide tunnel is divided into a supply section 24 and a vertically offset delivery section 22 there being disposed between these sections a lifting punch 21 that has a through- going recess 211 for a single contact that corresponds in shape to the profile of the contact. The punch also has a central slot 212 on the side of the recess, this slot terminating in the recess and being used to admit the passage of a transporter rod 18 that slides in the direction towards the electrode. The lifting punch 21 may be moved transversely to the transporter rod 18 by an amount equal to the offset distance V between the guide tunnel sections to permit a single contact to be lifted from the supply section to the level of the delivery section. This configuration makes it possible to guide the contacts to the carrier with complete reliability and in a well- defined position and to let the transporter rod 18 execute relatively long strokes while maintaining minimum cycle times. As shown, the lifting punch 21 severs the contacts from fed profiled contact material 14. <IMAGE>

Description

SPECIFICATION Welding unit for welding preferably profiled contacts on a carrier medium The invention relates to a welding unit to be used, for example, for welding of tapes at very high welding cycle rates.

Known apparatus of the above-defined kind works on the principle, for example, of supplying the contacts to the carrier medium via an indexing wheel. This method of operation naturally leads to increased dimensions of construction and the expenditure of increased amounts of control energy, which adversely affects precision of guidance and speed of operation.

In other welding units of the above-defined kind, the contacts are severed from a wire of contact material by a hardened clipping punch and subsequently pushed by the following wire of material toward the carrier in the next forward stroke.

In such known systems, either several contacts lie one behind the other or adjacent one another, bringing the disadvantage that any separating errors of the individual contacts will add up so that the smallest separating error necessarily leads to a malfunction of the welding operation and makes the functioning of this welding unit relatively unreliable. In another known system, a second, extended advancing stroke, operating in a separate working cycle, pushes the previously severed contact obliquely under the welding electrode but this method adversely affects the precision and speed of operation and, especially for very thin contact material, constantly poses the danger of kinking the contact material which is doing the pushing.

It is the basis of the invention to solve the problem of providing a welding unit with which it is possible to obtain high cycle rates and which is also distinquished by maximum compactness and operational reliability.

According to the invention, each contact is individualized and is transported in a precisely fixed attitude and with complete reliability through the supply region and onto the carrier under the electrode, so that the operational precision and reliability of the welding unit are increased.

A slot in the lifting punch makes it possible to return the punch from its raised position while the transporter rod is still in the immediate vicinity of the welding area so that even a very long stroke of the transporter rod has no adverse effects on the operational speed of the welding unit. After the individualized contacts have been raised to the level of the delivery section, it is no longer necessary to harmonize the relative motions of the transporter rod and the lifting punch, so that, from this time on, the motions of these components can be made to occur simultaneously and independently of one another with a view to optimum movement using relatively low intertial forces.Moreover, the lifting punch can be returned immediately after raising the individualized contacts and, thereafter, fulfill another operational function, thereby sharply raising the operating speed and the cycling rate that can be realized with the welding unit according to the invention while keeping the absolute velocities of the moving parts low. This leads to relatively low forces of acceleration and, consequently, to low stresses on the guidances of the moving parts and on the drive mechanism. This further increases the operational reliability and the life of the welding unit. The manner in which individualized contacts are received in the recess of the lifting punch and in the delivery section insures an absolute reliable and well-defined guidance which is only minimally affected the narrow slot.The transporter rod needs to apply only a very small force on the individualized contact to displace it within the delivery section, thereby preventing over-stressing the transporter rod even when it is very slender.

As already mentioned above, almost the entire cycle period is available for executing the motion of the lifting punch which is uncoupled from that of the transporter rod so that the path of the latter may be made very long, making it possible to use the welding unit according to the invention in a universal manner, i.e., for welding contacts to tapes or carriers of widely varying width.

It is not absolutely necessary for the lifting punch to execute a pure lifting motion. It should be stressed that the invention also encompasses solutions in which the delivery section and the supply section of the guide tunnel can have any arbitrary relative displacement and that the transporting punch that receives the individualized contacts can move between two terminal positions in such a way that the recess provided therein alternately comes into alignment with the shaped recesses of the two respective guide tunnel sections. In this general case, the transporting punch has a slot that medially and gradually conforms to the recess and that serves to receive a transporter rod of such dimensions as to permit it to move freely through the transporting punch during the latter's movements.

The lifting punch is required to move only a single contact from the plane of the supply section to that of the delivery section so that its kinetic energy and its energy requirements can be kept very low. The very narrow transporter rod also has only very iittle mass which favorably affects the dynamic conditions of the welding unit.

The further development according to dependent claim 2 brings the special advantage that the welding unit does not have to be enlarged even if the lifting punch must also serve as a parting tool. In that case, the welding unit operates in such a way that, shortly after the transporting rod has passed through, the lifting punch is moved back to its lower position so that it can already receive the profiled contact material being advanced by a certain length while the transporting rod is still in its working motion. After the transporting rod has returned to a position lying outside of the slot, the lifting punch is moved to perform the severing process of the contact material.

The further development according to claim 5 contributes to a further simplification of the welding unit because, in this case, the reciprocal motion of the electrode, necessary in any event, is also used to raise the lifting punch periodically. For this construction, the recess in the lifting punch that corresponds to the profile of the contacts is made with a certain amount of excess height so that the recess in the lifting punch may receive new contact material or a new individualized contact before the support arm has fully reached its final welding position. Preferably, the guidance is performed such that, shortly after the onset of the advance motion of the transporting rod, the support arm and the lifting punch are lowered into a position where the electrode lies a short distance before its final position.This distance is adapted to the above-described excess height of the recess in such a way that the supplied contact material may already be inserted in this position. In this position of the support arm or the electrode, the contact is pushed by the transporter rod between the welding electrode and the carrier.

The further development of claim 9 achieves the aim of operating the welding unit in any desired position and orientation without thereby adversely affecting the operational or functional reliability. For example, the welding unit may be flanged to an apparatus such that the transporter rod executes a vertical motion. The form-fitting placement of the contacts in the tunnel sections insures that the contacts cannot be lost and are guided toward the electrode without additional suction and positioning devices.

The further development according to claim 10 makes the welding unit still more compact and simpler from a technical viewpoint, requiring only a single drive means.

The further development of claim 1 3 brings the additional advantage that simple manual intervention and a maximum of operating convenience are adequate to convert the welding unit to process different types of electrodes or different electrode materials.

Further advantageous embodiments are the subject of the remaining dependent claims.

An exemplary embodiment of the invention will be described in detail hereinbelow with the aid of the drawing in which: Fig. 1 is a longitudinal section of the welding unit: Fig. 2 is a partial section along the line Il-Il of Fig. 1.

The welding unit has a housing 4 in which a support arm 1, holding an electrode 2, is rotatably and with low friction mounted on a shaft 3. The support arm 1 forms a current-carrying part of the welding unit. The other electrode, not designated in greater detail, is also connected to a welding current contact attached in insulated manner to the bottom of the housing 4.

Within the housing 4 is located a cam plate 5, driven from the outside by a chain or by other drive means and carrying several control cam segments, not further designated in detail, as well as a curve track 7 machined in the end-face.

The cam plate 5 controls the advancing and parting motions as well as the electrode movements with exact relative timing.

The periodic motion of the support arm is caused by a cam-follower roller 15, indicated by a dash-dotted line, which makes contact with a control cam surface of the cam plate 5 under spring bias tension.

As shown on the left of Fig. 1, the welding unit receives contact material 14 from a strip or a coil.

The pulled-off strip of material is then supplied by an advancing mechanism 8-13, to be described below, to a severing work-station in which individual contacts are made which are then pushed between the welding electrode 2 and a carrier 20 to carry out the actual welding process.

The welding unit works in such a way that, during a working cycle, there are performed an advancing motion of the contact material, a parting motion and a transport motion of the individualized contact.

The contact material 14 is initially seized between a clamping member 11 and an advancing slide 9 which moves against an exchangeable stop 23. The motion of the advancing slide 9 and the generation of the compressive force of the clamping member 11 are due to a cam-controlled gear system 8-1 3, also controlled by cam surfaces on the cam plate 5.

The elements of the cam-controlled gear train for the advancing slide 9 and for the pressure element 11 are pressed against the respective cam surfaces of the cam plate 5 by externally adjustable springs 13 and 10. For example, the spring 10 adjusts the advancing force and the spring 13 adjusts the clamping force between the advancing s!ide 9 and the clamping element 11.

The advancing system 8-13 supplies the contact material 14 to a supply section 24 which has a matrix-like configuration, i.e., it acts as a guide tunnel the cross-section of which is adapted to that of the profiled contact material 14 being processed. The supply section 24 ends at a lifting punch 21 which has a through-passage 211 whose shape corresponds substantially to that of the contact profile, as seen in Fig. 2. The lifting punch 21 may be moved back and forth between two terminal positions, transversely with respect to the extent of the supply section 24. In one of its terminal positions, shown in Fig. 1, its recess 211 is aligned with the supply section 24 while in the other terminal position, it is aligned with a delivery section 22 of the welding unit.

The delivery section 22 is displaced with respect to the supply section 24 by an amount V which is exactly equal to the working stroke of the lifting punch 21. The delivery section 22 is so positioned that its lower defining surface coincides with the plane of the carrier 20.

Preferably, the delivery section 22 is parallel to and above the supply section 24, as shown in Fig.

1. On the side facing the delivery section 22, the recess 211 in the lifting punch 21 changes to a central, narrow slot 212 the length of which is so chosen that it does not cover up an equally narrow guide slot 221 in the delivery section 22 when the lifting punch 21 is in its lower end position. A transporter rod 1 8 is disposed above the supply section 24, in alignment with the guide slot 221 and executes a reciprocal sliding motion in the direction of the guide slot 221. The transporter rod also occupies one of two terminal positions. In one terminal position, shown in Fig. 1 , the front end of the rod 1 8 comes to lie a short distance outside the slot 212.In the other end position, shown in Fig. 1 by a dash-dotted line, the front end of the transporter rod 1 8 is in a location where it positions the contact 19 to be welded exactly below the electrode 2.

The transport rod 18 is also driven by the cam plate 5, via the enveloping track 7.

According to the embodiment shown in Fig. 1, the lifting punch 21 is a cutting punch which causes the profiled contact material 14 to be clipped off as it moves from the plane of the supply section into that of the delivery section 22.

During the stroke of the lifting punch 21, the contacts are thus individualized. When the individualized contacts have been raised and when the recess in the punch 21 is aligned with the delivery section 22, the front end of the transporter rod 1 8 enters the slot 212, thereby causing the individualized contact to be moved from the recess 211 into and through the delivery section 22 under precise guidance, up to a position between the welding electrode 2 and the carrier 20.

The supply section 24, the lifting punch 21 and the delivery section 22 always form a replaceable set which, preferably, can be exchanged easily from the top of the frame 4.

In the embodiment shown in Fig. 1 , the lifting punch 21 is not driven separately, but together with the support arm 1 of the electrode 2. To this end, the lifting punch 21 is coupled in forcetransmitting and insulated manner with the support arm 1 by a claw-iike plate 25. In the area of the lifting punch 21, the support arm has a void through which extends a traction armature 27 the lower end of which forks around the punch 21 and the supply section 24 and which is pivotably attached to the frame 4 by a removable pin 6.The top end of the armature 27 has threads on which is carried an adjusting nut 26 between which and a pressure plate supported in the void of the support arm 1 is inserted a welding pressure spring 1 6. The spring 1 6 presses the support arm against the associated cam surfaces of the cam plate 5 via the cam-follower roller 1 5.

By rotating the adjusting nut 26, it is possible, as previously discussed in connection with the springs 13 and 10, to carry out an external fine adjustment of the compressive force between the cam-follower roller and the cam plate 5 i.e., of the welding pressure.

Except for the drive of the transporter rod 18, which is forcibly driven by a guide arm 1 7 traveling within an envelope track, the motions of the remaining moving parts of the welding unit take place at all times against the forces exerted by the springs 10, 13 and 16 which act as displacement agents and by the cam surfaces which act as restoring agents.

Hereinbelow will be given a description of the individual movements of the functional elements of the welding unit, operating in relatively timed manner. As the cam plate 5 turns, the cam surface segment being engaged by the control lever 12 drops off, so that the spring 1 3 causes the clamping member 11 and the lever 12 to clamp the contact material 1 4 against the advancing slide 9.

At this time, the cam segment associated with the advancing slide 9 also drops off so that the pivoting lever 8 associated with the advancing slide 9, urged by the spring 10, advances the contact material 14. The extent of the advance may be adjusted by exchanging the stop 23. The contact material 14 is now pushed through the matrix-like supply section 24 of the guide tunnel into the lifting punch 21 which is located near its lower end position and which, as explained above, has a passage over its entire extent L that is adapted to the profile of the contact material but is somewhat larger, i.e., higher. The length of the contact 1 9 which is finally delivered to the electrode is determined by the size of the stop 23.

The length L of the lifting punch 21, embodied here as a cutting punch, is so chosen that the largest contact to be used by the apparatus can be accommodated.

At this time, the third cam segment of the cam plate 5 being engaged by the cam-follower roller 1 5 rises and lifts the support arm 1 , together with the electrode 2 and the lifting punch 21 against the force of the welding pressure spring 1 6 until the contact 19, which had been severed and individualized during the upward motion, is aligned with the delivery section 22 of the guide tunnel. In its motion, the lifting punch 21 executes the stroke V (see Fig. 2), so that the lower edge of the recess 211 comes to lie in the sliding plane of the transporter rod 1 8.

When the lifting punch 21 has reached its upper terminal position, the pivotal lever 1 7, as guided by the envelope track 7, initiates the advance of the transporter rod 1 8 through the recess 211 of the lifting punch 21 and through the delivery section 22. During this motion, the contact 19 residing in the recess 211 is displaced toward the carrier 20 and to the location where the welding process is to take place.

Immediately after the contact 1 9 has departed from the recess 211 of the lifting punch 21, the third cam surface segment engaged by the camfollower roller 1 5 lowers the support arm 1 and the electrode 2 as urged by the welding pressure spring 16 until only a gap of approx. 0.1 mm remains between the carrier 20 and the underside of the electrode 2. The individualized contact 1 9 is now pushed into that gap by the transporter rod 18.

It will be seen that, due to the large mechanical advantage of the pivoting support arm 1 , the lifting punch 21 already occupies, at this time, a position lying approximately 0.05 mm above its lower terminal position. Due to the excess size of the recess 211, a new advancing stroke can already be started in this configuration.

During the return stroke of the transporter rod 18 and during the advancing motion of the advancing slide 9, the drop-off of the third cam segment engaged by the cam-follower roller 15 causes the electrode 2 to be placed upon the contact 19 with a pressure determined by the force of the welding pressure spring 16. At this moment, the welding process is triggered and during that process, the electrode 2 drops a little further by a distance equal to the melting depth.

Because of the sufficiently high slot 212, even this phase of the working cycle can also be used for the return stroke of the transporter rod 18. As soon as the transporter rod 18 has again departed from the recess 211, a new working cycle can begin.

The adjusting nut 26 on the tractor armature 27 rotatably mounted in the housing 4 makes it possible to set the welding pressure spring 16 to the required welding pressures, due consideration being given to the different mechanical ratios resulting from the different distances to the pivot 3.

Approximately 1/3 of the entire cycle period is available for the further transport of the carrier 20 during any one cycle because the contacts being welded are often so close to one another that the new contact can be brought under the electrode 2 only after the previously welded contact has been transported by a full step.

Nevertheless, due to the slotted lifting or cutting punch 21, all of the motions of the above described welding unit are so attuned to one another and merge so flawlessly that a welding time of 20 ms permits 800 cycles.

The above-described welding unit can be used to advantage even if the lifting punch 21 is to be supplied with preformed contacts having any arbitrary profile shape. In that case, the lifting punch should be equipped with a loading recess oriented transversely with respect to the direction of motion of the transporter rod 18 and communicating with an exteriorly accessible loading channel for the individual contacts. The reciprocating motion of the lifting punch 21 grasps a single contact 1 9 each time and places it in alignment with the delivery section 22 where the transporter rod 1 8 enters the recess 211 and the slot 212.In this case too, the contact 1 9 is guided with complete reliability and in a welldefined position along its entire path to the welding location which makes it possible to maintain the operational reliability of the welding unit at the highest possible level. If the lifting punch 21 is coupled to the delivery channel for individual contacts it can still be embodied so as to serve as a parting tool for severing individual contacts from a band of contact material.

The construction of the above-described welding unit makes possible a very simple conversion to the processing of contacts with different shapes. The replaceable set of elements consisting of the supply section 24, the lifting punch 21 and the delivery section 22 is easily accessible.

It will be recognized that, when the support arm 1 is pivoted around the pivot pin 3, the two guide tunnel sections are completely exposed. To perform the conversion, it is necessary only to remove the pin 6, which provides a pivotal bearing for the armature 27, from the housing 4 and to release the plate 25 that grasps the lifting punch in claw-like fashion and, in so doing, it is preferable to relieve the welding pressure spring 16 somewhat beforehand.

Because the distance between the lifting punch 21 and the pivotal point 3 of the support arm 1 is relatively great, it is not necessary to embody the lifting punch 21 with a cylindrical guide surface at the transition to the delivery section 22.

Claims (15)

1. A welding unit for welding preferably profiled contacts to a carrier, in which individualized contacts are pushed through a correspondingly profiled guide tunnel to a position between a welding electrode and the carrier, characterized in that the guide tunnel has a supply section (24) and a delivery section (22) vertically offset thereto and also includes a lifting punch (21) disposed therebetween and having a through-going recess for a single contact (19), said recess having a shape corresponding to the profile of the contact and a central slot (212) located on the side of the recess and terminating therein to admit the passage of a transporter rod (18) that slides in the direction of the electrode (2), said punch (21) being movable transversely to said rod (18) by an amount equal to the offset distance of the guide tunnel sections (24, 22) for the purpose of raising a contact (19) from the supply section (24) to the level of the delivery section (22).

2. A welding unit according to claim 1, characterized in that the profiled contact material (14) which is being continuously supplied to the lifting punch (21) through the supply section (24) can be severed.

3. A welding unit according to claim 1, characterized in that single, sequentially adjacent contacts (19) are supplied to the lifting punch (21) through the supply section (24) and are supplied by said punch to the delivery section (22) as individualized contacts.

4. A welding unit according to claim 1-3, characterized in that, adjacent to a supply section (24) aligned with the delivery section (22), there is disposed a single contact loading channel at right angles to said delivery section (22)and terminating transversely at the lifting punch (21).

5. A welding unit according to claim 1-4, in which the movable electrode is mounted on a pivotable support arm, characterized in that the support arm (1) also serves as a carrier for the lifting punch (21).

6. A welding unit according to claim 5, characterized in that the lifting punch (21) is disposed in force-transmitting manner within a claw-like plate (25) and is coupled to the support arm in insulated manner.

7. A welding unit according to claim 5 or 6, characterized in that the transporter rod (18) can be moved into and through the slot (212) of the lifting punch (21) independently of the position of the support arm (1).

8. A welding unit according to one of the preceding claims, characterized in that the transporter rod (18) is controlled by means of an envelope track (7).

9. A welding unit according to one of the preceding claims, characterized in that respective cam surfaces act as restoring elements and springs (10, 1 3, 1 6) act as advancing elements for actuating the support arm (1) and the material advancing system (8 to 13).

10. A welding unit according to claim 9, characterized in that the envelope track (7) and the cam surfaces are disposed on a single cam plate (5).

11. A welding unit according to claim 9 or 10, characterized in that all springs (10, 13, 16) are adjustable individually from the outside.

12. A welding unit according to claim 9 to 11, characterized in that the advancing mechanism (8-1 3) includes an advancing slide (9) that works against a replaceable stop (23).

13. A welding unit according to claim 1 to 12, characterized in that the lifting punch (21) and the supply and delivery sections (22, 24) form a replaceable set of elements.

14. A welding unit according to claim 9 to 13, characterized in that the actuating spring (16) of the support arm (1) is supported on a releasable traction armature (27) that envelops the lifting punch (21) in fork-like manner and is mounted pivotably on a releasable pin (6).

15. Apparatus for welding contact members to a carrier comprising profiled guide means adapted to transport individual contact members separately and in a predetermined fixed orientation to the welding site.

1 6. Apparatus substantially as herein described and with reference to the accompanying drawings.