AUTOMATIC WELDING PROCESS OF A PLATELIKE BODY INSIDE METAL BARS AND THE MACHINE FOR THE IMPLEMENTATION OF SAID PROCESS

Abstract: A process which provides the following phases in succession: the bar (29) and the platelike body (30) are placed on a respective support; the platelike body is drawn out and electrically connected to the first electrode (7) of the welding machine: the unit composed of ''first electrode - platelike body (7-30)'' is moved such as to allow the insertion of the platelike body inside the bar (29), into a place which coincides with the junction line between a first and a second part (11-12) of the second electrode of the welding machine; said first and/or second part (12 and 13) of the second electrode is moved along said junction line and as soon as it comes into contact with the bar an electric potential between said first and second electrode is applied.

Description: AUTOMATICWELDINGPROCESSOFAPLATELIKEBODYINSIDE METALBARS ANDTHEMACHINEFORTHEIMPLEMENTATION OFSAIDPROCESS The present invention relates to a process for the automatic soldering of a platelike body inside bars having a transverse, polygonal-shaped section and to the soldering machine which will perform said process. The Italian patent application No. 23804 A/83 describes a modular structure fit for carpentry works, mainly composed of a plurality of bars that are assembled through joints. These latter are so shaped as to accomodate the screw heads whose shank can be screwed into a platelike body arranged at both bar ends, perpendicular to their axis. According to a preferential embodiment said platelike body is joined to the bars with solder. The bars have a transverse polygonal-shaped section and the automatic soldering operations require therefore the overcoming of technical problems connected with the arrangement of the platelike body inside the bars and with the soldering of more sides (preferably four) of the platelike body to the respective internal faces of the bar. It is well known that the most suitable soldering process to. be performed under an automatic process is called "thermal resistance" process where the heat, through the Joule effect, is produced on the contact surface among the sections to be soldered, which is placed between a pair of electrodes. When such a process is separately performed by soldering a side of the platelike body to the respective internal face of the bar, no particular technical problems are evidenced. Such a process is not compatible with the velocity of the automatic production line of the structure as this would require the execution in succession of four soldering operations by spending more time than is required by other bar processings such as boring, shearing, etc. If ' the soldering process is divided into four different operations, a sensible reduction in the velocity of the production line is reached. Purpose of the present invention is the determination of a suitable process able to perform the simultaneous soldering of each side of the platelike body (for example, four or more sides) to the respective internal portion of the bar as well as to realize a suitable machine able to carry out such a process. To this end the process, according to the invention, foresees the execution in succession of the phases as hereafter specified: the bar and the platelike body are placed on a respective support; the platelike body is drawn out and electrically connected to the first electrode of the soldering machine; the unit composed of "first electrode - platelike body" is moved such as to allow the insertion of the platelike body inside the bar, into a place which coincides with the junction line between the first and the second part of the second electrode of the soldering machine; said first and/or second part of the second electrode is moved along the junction line and as it comes into contact with the bar an electric potential between said first and second electrode is applied. Further characteristics of the process according to the invention will be indicated in the description relative to the realisation of an automatic machine able to carry out the said process, better shown in the enclosed drawings, whereas: figure 1 shows the machine as it is realised according to the invention; figure 2 shows the soldering unit of the machine in Fig. 1, on enlarged scale; - figure 3 shows the different phases of the process carried out according to the invention; figure 4 shows a longitudinal and a transverse section of a bar's portion in order to show the structure of the platelike body and of the second electrode of the soldering machine. In figure 1 it is clearly shown that the machine is mainly constituted by a column 1 and a bench 2. Column 1 forms the soldering machine and includes devices 3 for the accomodation and the locking of the bar and devices 4 for the accomodation and the support of the platelike body. The bench 2 encloses the devices necessary to allow the automatic insertion of the platelike body inside the bar in order to carry out the soldering operations. In particular the bench provides the presence of a slide 5 along which a flat body 6 moves, suitable to support all the devices which allow the insertion mentioned above. An earth electrode 7 of the soldering machine, a device 8 for the drawing out of the platelike body and a locking device 9 of the same body are located on the flat surface 6. The flat surface 6 is operated by a piston controlled by a pneumatic system 10. On enlarged scale, Fig. 2 shows the soldering machine as well as the devices 3 and 4 of figure 1. Said soldering machine contains the second electrode which is composed by a first and a second part (11 and 12 respectively). According to the invention the first part 11 is fixed, while second part 12 is so shaped as to be moved vertically along slide guides (not illustrated) provided on said colou n 1. The shape of the working surface for the first and second part is clearly stated hereafter with reference to figure 4. Devices 3 suitable for the location and the locking of the bar are constituted by support devices 13, devices 14 which prevent from the vertical shifting and devices 15 which prevent from the horizontal shifting. Devices 14 are composed by a plate having the inferior part grooved according to a profile which coincides with the edge of the bar with which it will come into contact and having the superior part connected to a toggle mechanism 16. Said mechanism allows the shifting of the plate according to a defined circumference arc and is therefore adapted to engage the bar among said support devices 13 and said plate 14. Devices 15 are fit to prevent the bar from the horizontal shifting and are mainly constituted by a plurality of pins 17 which are operated by a device 18, pneumatic controlled. Under operating conditions the pins are placed inside holes, usually provided inside the bar, and prevent the bar from the horizontal shifting. Devices 4 for the placing and support of the platelike body are constituted by an element 19, with U-shaped section, which has its sides crossed by small pistons, pneumatic controlled, a section of which comes out as to the inner sides. The platelike body is therefore adapted to be placed between the sides of ^ element 19 so as to link against the portion of said pistons 20 which comes out. Figure 2 shows further the shape of said first electrode 7 of the soldering machine which is constituted by more copper blocks anchored to a support 22 by means of a joint 21. The shape of the portion 7' of said electrode is similar to the profile of the platelike body. In particular the front side of said portion 7' is so shaped as to present the same form of the platelike body, in order to enlarge the contact surface by diminishing the electric resistance. Still on Figure 1, it is possible to note that the device which draws out the platelike body 8 is placed on a further flat surface 23, which can freely slide along the rack, moved by another piston, operated by a pneumatic controlled system 24. On this flat surface 23 a motor 25 is placed, which causes the rotation of a pin 26 having a threaded end. Said pin is so shaped as to cross the front bar of said locking device 9 as well as to cross said first electrode 7, coming out from the front side of said portion 7'. The axis of pin 26 coincides with the axis of the hole provided on the platelike body, so that by operating the motor 25 and by causing the sliding of the flat surface 23, the pin 26 is screwed into the hole of the platelike body. When the screwing operations begins, the pistons 20 of the loading element 4 prevent the platelike body from the upsetting. The pin 26 presents a part of an enlarged section 27 adapted to act against the front bar of said locking device 9 which is moved by another piston 28, pneumatic controlled. Once the drawing out device has completed the screwing process described above, the piston 28 carries back the locking device 9 , whose front bar acts against said enlarged part 27 of pin 26, pulling it back. Said shifting is completed when the platelike body is joined to the front side 7' of the first electrode 7. In order to reduce the electric resistance between the platelike body and the first electrode, the adherence acquires a sensible value (for example, some hundreds of Kg). The insertion of the platelike body into the bar is performed by said pneumatic system 10, which pushes forward the flat surface 6 and consequently all the devices placed on it, the unit composed of "first- electrode - platelike body" included. The sliding forward of this latter is allowed by the pulling back of the pistons 20 of the loading unit 4, which do not come out from the inner sides of said body 19 and can therefore allow the sliding forward of said combined unit. The insertion of the platelike body into the bar is made easier by the way of joint 21 provided on the first electrode 7 which, by causing a light oscillation, can facilitate the entering of the platelike body. Following the single phases of the process according to the invention and with the help of fig. 3 the working of the devices mentioned above will be better evidenced. The first phase is shown in fig. 3a and requires the placing of bar 29 and platelike body 30 on the relative support. In particular the bar 29 is pushed forward till it comes into contact with an element of the soldering machine. The second phase is illustrated in fig. 3b and 3c. In particular said phase provides the switching on of motor 25, causing the rotation of pin 26 and the sliding forward of said flat surface 23 by means of the device 24. The rotation and sliding forward of the threaded pin 26 causes its screwing into the hole of the platelike body of a predetermined value. Once the screwing operation is completed, the motor 25 switches off and the sliding forward of the flat surface 23 as well as the sliding back of said locking device 9 stop, as shown in fig. 3c. The device 9 acts against the enlarged portion 27 of pin 26 by causing its sliding back as well as the pulling back of. the platelike body 30 till the same joins to this front side 7' of the first electrode 7 using a predetermined force. The third phase is illustrated with the help of fig. 3d and provides the sliding forward of said flat surface 6, controlled by the device 10, and of the unit composed by the electrode 7 - platelike body 30 until this latter is inserted into the bar 29. The fourth phase is shown in fig. 3e and provides the performance of the soldering operations which are realised when the portion 12 of the second electrode comes into contact with the bar 29. From that time forth a voltage between the first and second electrode (7, 11 and 12) is applied and the platelike body is soldered to the bar by means of Joule effect, as better evidenced in fig. 4. The process, according to the invention, requires the perfomance of the four phases described above and if necessary the performance of other two phases to make easier the soldering operations and to check the efficiency of the soldering operation. Once the process described above is completed and before the machine sets the reset operation off, a control is carried out on the soldering operation. Said check provides the applying of a predetermined force to said platelike body 30, through the pin 26, the device 9 and the flat surface 6. Should the soldering operation be not well executed, the force so applied will cause the disengagement and the carrying back of the platelike body. The devices which determine the carrying effect that the platelike body 30 has substained, are placed on the bench 2 and if the carrying effect exceeds a predetermined value, an alarm is released. The means cited above (see fig. 1) are constitued by a photoe itting element 31 which emits a light ray usually interrupted by a screen 32 provided with a hole. If the sliding exceeds a predetermined value, the hole's axis coincides with the axis of the light ray which causes the release of an alarm as it reaches a photoreceiving unit 33. According to another embodiment the means for the determination of the carrying effect can be substitubed by other means (not illustrated) fit to identify a pressure fall in the pneumatic system when the platelike body is ι disengaged. Said means release an alarm when a pressure fall is determined. The return to the operated position provides the rotation of motor 25 in the opposite direction as to the screwing direction and the reset of said flat surfaces 6 and 23 to the original state. The soldering operations are facilitated through the realisation of drawings 34 in the bar's sides, as shown in fig. 4a and 4b, where a bar's portion is longitudinally and transversally intersected. In the same figure the first and second part 11 and 12 of the second electrode are schematically illustrated in order to better evidence the shape and arrangement of the relative working surfaces. From the fig. 4a it is evident that the drawings 34 are elliptical-shaped having an axis dimension greater than the thickness of the platelike body 30. The drawings 34 provide the concentration of the current flowing in the surfaces to which they are interested and therefore cause a partial fusion of the surface which is in contact with the sides of the platelike body 30. Said partial fusion develops into a penetration of the platelike body in the drawings by causing a sensible increase of the contact resistance between the bar 29 and the platelike body 30. The process and the machine according to the invention allow the contemporaneous soldering of four sides of the platelike body to the inner sides of the bar, spending a time which is compatible with the working speed of the automatic production line and obtaining a contact particularly valid, due to the shape of said drawings 34. The drawings 34 are realised just when the iron sheet is cut to obtain the bar. A hint to a pneumatically operated machine has been made in the description above; without digressing from the invention said system can be replaced by an oleodynamic or other type system.

Claims: CLAIMS 1. Process for the automatic soldering of a platelike body inside a metal bar having a polygonal-shaped section, characterized in that it requires the performance of the following phases: - the bar (29) and the plajelike body (30) are placed on the respective support (3 respectively 4); the platelike body (30) is drawn out from the support (4) and electrically connected to the first electrode (7) of the soldering machine; - the unit composed of the "first electrode - platelike body (7-30)" is so shifted as to determine the insertion of this latter inside the bar (29) in a place which coincides with the conjunction line between a first and a second part (11 and 12) of the second electrode of the soldering machine; - said first and/or second part (12 and 13) of the second electrode is shifted along said conjunction line and as soon as it contacts the bar, an electric power between the first and the second electrode (7 and 11, 12) is applied. 2. Process as claimed under claim 1 characterized in that at the end of the soldering process a check phase is actuated, which provides the applying of a predetermined force to said platelike body (30) and the check of the efficiency of the soldering once the sliding caused by the said power is terminated. 3. Process as claimed under claim 1 characterized in that before starting the soldering process on the bar's portion interested, a plurality of long-shaped drawings (34) are realised and the dimensions of their main axis should be greater than the thickness of the platelike body (30). 4. Process as claimed under claim 2 characterized in that said check phase consists in applying a predetermined force to said platelike body (30) and in checking the efficiency of the soldering operation considering the pressure fall of the pneumatic system which follows the application of said power. 5.. Machine for the implementation of the process as claimed under the above claims, characterized in that it provides the following technical features: a soldering machine comprising a first electrode (7), adapted to perform the horizontal sliding and a second electrode composed by a first and a second part (11 and 12), one of which at least is fit to cause the sliding perpendicularly to the first electrode (7), having the working surfaces so shaped as to realise a profile complementary to the one individuated by the respective bar's sides with which they should come into contact; a first device (3) suitable to accomodate and to lock the bar (29) in such a way as to have the axis coinciding with the sliding direction of the first electrode (7); a second device (4) suitable to accomodate and to support the platelike body (30) perpendicularly to the sliding direction of the first electrode (7); a third device (8), suitable to perform the screwing cycle of a threaded pin (26) into a hole provided on the platelike body (30); - a locking device (9) suitable to cause the adherence of the platelike body (30) to a surface of the first electrode (7) by using a predetermined force; an insertion device (6) suitable to cause a sliding of the third device (8) and of the locking device (9) until the platelike body (30) is completely inserted into the bar (29); 6. Machine as claimed under claim 5 characterized in that the first device (3) which provides the accomodation and locking of the bar (29) requires the following main features: support devices (13) having the working surfaces arranged at angle complementary to the bar's sides (29) with which they should come into contact; fourth devices (14) suitable to prevent the vertical sliding of the bar (29), composed of a plate (14), having the bottom side a profile grooved like the bar's portion with which it . should come into contact and the upper side connected to a toggle mechanism (16); fifth devices (15) suitable to prevent the horizontal sliding of the bar composed at least of a pneumatically operated pin (17), adapted to be placed inside a hole provided on the bar (29). 7. Machine as claimed under claim 5, characterized in that said second device (4) suitable to accomodate and to support the platelike body (30) is composed by an element (19), U-shaped, having the sides crossed by pistons (20) which come out from the inner sides and then can be drawn back, controlled by a pneumatic controlled system. 8. Machine as claimed under claim 5 characterized in that said third device (8) is composed by a pin (26) having a threaded end connected to a motor (25) mounted on a flat surface (23) which can freely slide in respect to another flat surface (6) operated by a pneumatic system (24). 9. Machine as claimed under claims 5 and 8 characterized in that said locking device (9) is composed by a pneumatically operated unit, having the front bar so shaped as to act against an enlarged portion (27) of said pin (26), causing its sliding and that of the platelike body (30), applying a predetermined force, which determines the adherence of the platelike body (30) to the first electrode (7). 10. Machine as claimed under claim 5 characterized in that said insertion device (6) is constituted by a flat surface suitable to support said third device (8), the locking device (9) and the first electrode (7) suitable to cause the horizontal sliding through a pneumatically operated system (10). 11. Machine as claimed under claims 2 and 5 characterized in that the means suitable to check the efficiency of the soldering operation are constituted by a photoemitter unit (30), by a photoreceiver unit (33) and by a screen (32). 12. Process and machine as described above and illustrated in the enclosed drawings as well as any other element of the same, combined or single parts.

Inventors: CECCHELLERO SERGIO, SALVATORE DANIELE, CECCHELLERO, SERGIO, SALVATORE, DANIELE
Applicants: ITALTEL SPA, ITALTEL TECNOMECCANICA S.P.A.
Application year: 1986
Main classification: B23K11
IPC codes: B23K11