TRANSPORT UNIT FOR TRANSPORTING PRINTED CIRCUIT BOARDS, AND SOLDERING SYSTEM

Abstract

A transport unit for transporting printed circuit boards along a direction of transport within at least one zone of a soldering system, in particular a reflow soldering system, characterized in that a base part is provided with an output shaft that can be driven, and with at least two output wheels which are rotatably coupled to the output shaft, in that at least two drive parts which can be releasably fastened on and removed from the base part are each provided with a drive wheel in such a manner that the drive parts have drive rollers which are rotatably coupled to the drive wheel, and which act on the printed circuit board to transport the printed circuit board through the zone, and in that, when the drive parts are fastened to the base part, each of the output wheels is in engagement with the associated drive wheel.

Claims

1. A transport unit for transporting printed circuit boards along a direction of transport within at least one zone of a soldering system, wherein a base part is provided with an output shaft that can be driven, characterized in that at least two output gears which are rotatably coupled to the output shaft are provided, in that at least two drive parts which can be releasably fastened on and removed from the base part are each provided with a drive gear in such a manner that the drive parts have drive rollers which are rotatably coupled to the drive gear, and which act on the printed circuit board to transport the printed circuit board through the zone, in that, when the drive parts are fastened to the base part, each of the output gears is in engagement with the associated drive gear, and in that receiving parts which extend in the direction of transport are provided on the base part for receiving and for releasably fastening the drive parts, wherein the receiving parts each have the output gear which can be brought into engagement with the drive gear and which can be driven by the output shaft.

2. The transport unit according to claim 1, characterized in that the drive parts have a plurality of drive rollers arranged one behind the other in the direction of transport, wherein adjacent drive rollers are rotatably coupled to one another via gears, and wherein at least one gear is rotatably coupled to the drive gear.

3. The transport unit according to claim 1, characterized in that the base part is designed in the manner of a frame, with two side parts extending in the direction of transport, and with two struts extending in the transverse direction, running transverse to the direction of transport.

4. The transport unit according to claim 3, characterized in that the arrangement is such that the frame can be releasably and removably arranged in the soldering system.

5. The transport unit according to claim 3, characterized in that the output shaft extends in the transverse direction and is arranged in a rotatably mounted manner on the two side parts.

6. The transport unit according to claim 3, characterized in that at least one receiving part is arranged in a manner allowing movement and adjustment on the struts in the transverse direction.

7. The transport unit according to claim 6, characterized in that the receiving parts each provide a coupling gear which is rotatably coupled to the output gear and to the output shaft, and which is arranged on the output shaft in a manner allowing axial displacement.

8. The transport unit according to claim 6, characterized in that at least one adjusting shaft is provided, which extends in the transverse direction and which is coupled to at least one receiving part in such a manner that the receiving part can be displaced in the transverse direction by the rotation of the adjusting shaft.

9. The transport unit according to claim 1, characterized in that two edge receiving parts are provided, each for receiving one edge drive part, wherein the drive rollers of one edge drive part face the drive rollers of the other edge drive part, and are arranged in such a manner that, when the transport unit is in operation, the printed circuit board rests, in the region of its free longitudinal edges, on the drive rollers.

10. The transport unit according to claim 9, characterized in that longitudinal guides for guiding the printed circuit boards in the direction of transport are provided on the edge drive parts.

11. The transport unit according to claim 9, characterized in that at least one center receiving part for the purpose of receiving a center drive part is provided between the edge receiving parts.

12. The transport unit according to claim 11, characterized in that the transport unit has two transport tracks running in the direction of transport, wherein at least one of two edge receiving parts and one center receiving part is provided for each transport track.

13. A soldering system for continuous soldering of printed circuit boards in a process channel along a direction of transport, wherein at least one preheating zone at least one soldering zone, and at least one cooling zone are provided in the process channel, wherein a pressure chamber is provided in the soldering zone, which has a base part and has a cover part which can be lifted relative to the base part during operation of the reflow soldering system, characterized in that a transport unit for transporting the printed circuit boards along the direction of transport within the at least one zone of a soldering system is provided at least in one of the zones and/or in the pressure chamber, wherein the base part is provided with an output shaft that can be driven, characterized in that at least two output gears which are rotatably coupled to the output shaft are provided, in that at least two drive parts which can be releasably fastened on and removed from the base part are each provided with a drive gear in such a manner that the drive parts have drive rollers which are rotatably coupled to the drive gear, and which act on the printed circuit board to transport the printed circuit board through the zone, in that, when the drive parts are fastened to the base part, each of the output gears is in engagement with the associated drive gear, and in that receiving parts which extend in the direction of transport are provided on the base part for receiving and for releasably fastening the drive parts, wherein the receiving parts each have the output gear which can be brought into engagement with the drive gear and which can be driven by the output shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the drawings:

[0025] FIG. 1 is a reflow soldering system in side view;

[0026] FIG. 2 is the reflow soldering system according to FIG. 1 in a front view;

[0027] FIG. 3 is the top view of the soldering zone of the reflow soldering system, without the cover;

[0028] FIG. 4 is a perspective view of a two-track transport unit;

[0029] FIG. 5 is the transport unit according to FIG. 4, without a side cover and without a side part;

[0030] FIG. 6 shows individual parts of the transport unit according to FIG. 4, with the drive part removed;

[0031] FIG. 7 is a view of a drive part attached to a receiving part.

DETAILED DESCRIPTION

[0032] FIG. 1 shows a reflow soldering system 10 for continuous soldering of items to be soldered. The reflow soldering system 10 has an entrance 12 and an exit 14, wherein the items to be soldered enter the reflow soldering system 10 via the entrance 12, and are removed from the reflow soldering system 10 via the exit 14. The item to be soldered is transported through the reflow soldering system 10 along a direction of transport 18 of a process channel 16 indicated in FIG. 1.

[0033] A preheating zone 20, a soldering zone 22, and a cooling zone 24 are provided in the process channel 16. In the case of the reflow soldering system 10 shown in FIG. 1, a machine casing 25 with three sections 26, 28 and 30 is provided for covering the process channel 16.

[0034] As is clear from FIGS. 1 and 2, a communication unit 36 with a display screen and an input device is provided, by means of which communication can take place with a machine controller of the reflow soldering system 10.

[0035] The item to be soldered, that is, the printed circuit board configured with solder paste and fitted with electronic components, is first heated in the preheating zone 20 to a temperature which is below the melting temperature of the solder paste. In the soldering zone 22, the printed circuit board is heated for a specific period to a process temperature which is above the melting point of the solder paste, such that it melts in the soldering zone to solder the electronic components to the printed circuit board. The item being soldered is cooled in the cooling zone 24, such that the liquid solder solidifies before the item being soldered is removed at the exit 14 of the reflow soldering system 10.

[0036] A transport system 34 is provided within the reflow soldering system 10 for transporting the printed circuit boards along the direction of transport 18.

[0037] As is clear from the front view of FIG. 2, the covering hood 25 can be pivoted open about a pivot axis 32 extending parallel to the direction of transport 18. The transport system 34 is accessible by pivoting the covering hood 25—to allow visual inspection, maintenance, cleaning, setup, replacement, and, optionally, repair.

[0038] In the soldering zone 22, there is a pressure chamber in the form of a vacuum chamber 40, which is formed by a base part 42—shown in the top view according to FIG. 3—and by a cover part, which is not shown in the figures, with which the base part 42 can be closed off.

[0039] During operation of the reflow soldering system 10, the cover part can be lifted off the base part 42 by means of a lifting mechanism. It is necessary to lift the cover part in order to be able to move the printed circuit boards into the vacuum chamber 40. As soon as the printed circuit boards are situated in the vacuum chamber 40, the cover part is lowered so that it comes to rest on the base part 42. In a next step, the vacuum chamber 40 is evacuated with a vacuum pump (not shown), such that a suitable negative pressure is created in the vacuum chamber 40. Due to the negative pressure, air which is contained in the liquid solder, in particular, is expelled. After a brief application of negative pressure to the vacuum chamber 40, the cover part is raised via a corresponding activation of the lifting mechanism, such that the printed circuit boards can move out of the vacuum chamber 40. Advantageously, the printed circuit boards move through the vacuum chamber 40 within the described process at a constant speed or at a variable speed.

[0040] In the top view according to FIG. 3, the base part 42 of the pressure chamber 40, and the transport unit 50 provided in the base part 42, are shown schematically. A total of two transport tracks 60 running parallel to one another is provided, along which printed circuit boards can be transported next to one another along the direction of transport 18 through the process chamber 16 and the vacuum chamber 40. The vacuum chamber 40 provides a chamber entrance 62 in which circuit boards coming from the transport system 34 are transferred to the transport unit 50, and a chamber exit 64 in which the circuit boards are transferred back to the transport system 34.

[0041] The transport unit 50, which can be inserted into the pressure chamber 40 and/or into the base part 42 of the pressure chamber 40, is shown in FIG. 4. The transport systems 34 indicated in FIG. 3 can be transport systems which correspond to the transport unit 50. However, it is also conceivable that differently designed transport systems are used there, since these transport systems 34 are subject to less stress than the transport unit 50 which is used inside the pressure chamber 40.

[0042] The transport unit 50 comprises a base part 66, which is designed like a frame and has two side parts 68 extending in the direction of transport 18, and two struts 70 running in the transverse direction. Also provided on the base part 66 is an output shaft 72 which is rotatably mounted on the side parts 68 and which can be driven at its free end 74 via a rotary drive, which is not shown in detail.

[0043] On the base part 66 between the side parts 68, there is a total of six receiving parts 76 to 81, on which drive parts 86 to 91 are provided which can be releasably fastened and removed. FIG. 5 shows the transport system 50 with only one side part 68, and with only the three receiving parts 76 to 78 and the three drive parts 86 to 88.

[0044] Each of the drive parts 86 to 91 has a drive wheel 92, and each of these is in engagement with, in the assembled state, as can be seen in particular from FIG. 5 and FIG. 7, an output wheel 94, which is provided on the base part 68 and/or on the given receiving part 76 to 81. The drive wheels 92 and the output wheels 94 are arranged coaxially with one another, and also coaxially with the output shaft 72 and with the struts 70. The arrangement is such that, when the drive parts 86 to 91 are removed, as shown in FIG. 6, each of the drive wheels 92 is lifted off the given output wheel 94, and accordingly is no longer in engagement with the given output wheel 94.

[0045] Each of the drive parts 86 to 91 also has drive rollers 96 rotatably coupled to the respective associated drive wheels 92, on which drive rollers the printed circuit boards come to rest during operation, and which transport the printed circuit boards through the given zone 18, 20, 22 and/or through the pressure chamber 40. As is also clear from FIGS. 4, 5 and 6, a plurality of drive rollers 96 arranged one behind the other in the direction of transport 18 is provided on the drive parts 86 to 91, wherein adjacent drive rollers 96 are rotatably coupled to one another via gears 98. One of these gears forms the drive wheel 92 which, as is clear from FIG. 7, is in engagement with the output wheel 94 in the assembled state.

[0046] As explained in relation to FIG. 3, the transport unit 50 can be used to transport printed circuit boards along the two transport tracks 60. The receiving parts 76, 77 and 78 with the drive parts 86, 87 and 88 are assigned to one of the transport tracks 60 in this case. The receiving parts 79, 80, 81 with the drive parts 89, 90, 91 are assigned to the second transport track 60.

[0047] The receiving parts 76, 77, 78 and the drive parts 86, 87, 88 of only one transport track 60 are shown in FIG. 5. The receiving parts 76, 78 are designed as edge receiving parts, and the central receiving part 77 is designed as a center receiving part. The drive parts 86, 88 are designed as edge drive parts, and the central drive part 87 is designed as a center drive part. The edge receiving parts 76, 78 serve the purpose of receiving edge drive parts 86, 88, and the central receiving part 77 serves the purpose of receiving the center drive part 87. The arrangement is such that the drive rollers 96 of the edge drive parts 86, 88 are arranged facing one another, such that during operation of the transport unit 50, each printed circuit board comes to rest on the respective drive rollers 96 in the region of its free longitudinal edges. The edge drive parts 86, 88 and 89, 91 have longitudinal guides 116 which serve to guide the circuit boards in the direction of transport 18 during operation of the system. The center drive part 87 is provided to support the printed circuit boards in the central region, and additionally drives the central regions of the printed circuit board.

[0048] The receiving parts 79, 80 and 81 and the associated drive parts 89, 90 and 91, which form the second transport track 60, correspond in structure to the receiving parts 76, 77, 78 and drive parts 86, 87, 88 of the first transport track 60.

[0049] In order to be able to adjust the width of each of the transport tracks 60 and/or the position of the drive parts 86 to 91 in the transverse direction, the receiving parts 78 to 81 are arranged in a manner allowing movement on the struts 70 by means of guide rollers 100. To adjust the receiving parts 76 to 81, two spindle shafts 102 and 104 are provided which are rotatably mounted on the side parts 68 and which can be driven via rotary drives which are not shown in the figures. The spindle shaft 102 is coupled to the edge receiving parts 78 and 81 via spindle nuts 106 to allow movement, such that when the spindle shaft 102 rotates, the two receiving parts 78 and 81, and thus the drive parts 88 and 91, can be adjusted. The spindle shaft 104 is coupled to the center receiving parts 77 and 80 via spindle nuts to allow movement, such that when the spindle shaft 104 is rotated, the receiving parts 77 and 80 and thus the drive parts 87 and 90 can be adjusted in the transverse direction.

[0050] In order to enable the output wheels 94 to be rotatably coupled to the output shaft 72 even when the receiving parts 76 to 81 are being adjusted in the transverse direction, the receiving parts 76 to 81 have coupling wheels 108 rotatably coupled to the output wheels 94, which is particularly clear from FIG. 7. The coupling gears 108 each have a receiving contour 110 that is complementary to the cross section of the output shaft 72, such that the coupling gears 108 and thus the associated receiving parts 76 to 81 can be displaced with the drive parts 89 to 91 on the output shaft 72 in the transverse direction, and nevertheless are still rotatably coupled to the output shaft 72. In the embodiment shown in the figures, the output shaft 72 has a hexagonal cross section, and the receiving contour 110 provided on each of the coupling wheels 108 is designed as a hexagonal recess.

[0051] As is clear from FIG. 6, the drive parts 86 to 91 can be removed vertically from the associated receiving parts 76 to 81 in a simple manner. All that is required for this purpose is fastening means, which are designed as hand-operated fastening screws 112 in FIG. 6. After the fastening screws 112 have been unscrewed, and each of the drive parts 86 to 91 has been removed, each of the drive wheels 92 also lifts off from the associated output wheel 94. When each of the drive parts 86 to 91 is placed back onto the respective receiving parts 76 to 81, each of the drive wheels 92 comes back into engagement with the associated output wheel 94.

[0052] As is clear from FIG. 4, retaining lugs 114 are provided on the frame, via which the entire transport unit 50 can be removed from the soldering system 10 or from the corresponding zone 20, 22, 24 or the pressure chamber 40 in a simple manner.

[0053] The reflow soldering system 10 described or the drive unit 50 described has the advantage that the individual drive parts 86 to 91 can be exchanged, inspected, serviced and cleaned in a simple manner. Furthermore, the entire transport unit 50 can also be exchanged. The drive parts 86 to 91 described are comparatively robust, since only gears, and no chains or belts, are used. Furthermore, intensive and/or automatic lubrication can also be dispensed with. The embodiment with gears is also significantly less sensitive to contamination in the form of condensate or solder residue. Furthermore, in comparison to conventional chain drives, no chain tensioning device is required.