CENTRAL SUPPORT TO SUPPORT THE ELEMENT TO BE WELDING, TRANSPORT UNIT AND WELDING SYSTEM WITH CENTRAL SUPPORT.

Abstract

The present invention relates to a central support (66, 166) for supporting elements to be welded (170) during transport along a transport direction (18) through a welding device (10), a transport unit (50) and a welding device (10) with such a central support (60, 166).

Description

CENTRAL SUPPORT TO SUPPORT THE ELEMENT TO BE WELDING, TRANSPORT UNIT AND WELDING DEVICE WITH CENTRAL SUPPORT FIELD OF INVENTION The invention relates to a central support for holding components to be soldered during transport along a transport direction through a soldering device. The component to be soldered can be a printed circuit board assembled with electronic components or a product support for other products, and in particular for circuit boards assembled with electronic components. The soldering device can be, in particular, a reflow soldering device for the continuous soldering of printed circuit boards assembled with electronic components or a drying device for drying printed circuit boards that have been assembled with components. The component to be soldered is preferably supported in the central area.The central support has a base part and a drive part that is height adjustable with respect to the base part, where the drive part has a transport position, in which it acts against the element to be welded, and is adjustable to a lowering position in which it does not act against the element to be welded. The invention also relates to a transport unit with such a central support. While transport units without a central support hold the respective soldered element at the edges parallel to the transport direction and transport it in that direction, the central support supports the element to be soldered in the central area. Central supports are particularly advantageous when soldering or drying printed circuit boards or supports for relatively large products. They prevent bending or sagging of the soldered elements in their central area, which can occur particularly due to the heating of the element to be soldered, thus ensuring functionally reliable transport. The invention also relates to a particular soldering device, a reflow soldering device for continuous soldering of assembled printed circuit boards, or a drying device for drying assembled printed circuit boards, wherein the element to be soldered can be conveyed along a conveying direction through at least one zone, wherein a conveying unit with a central support or a central support is provided in at least one zone. In particular, at least one preheating zone, at least one soldering zone, and preferably also a cooling zone may be provided as zones in a process channel. BACKGROUND OF THE INVENTION DE 10 2005 055 283 A1 discloses a height-adjustable central support comprising a link chain driven by at least one drive wheel, wherein the link chain is guided in a support. The provision of such a link chain has proven problematic because it requires continuous or at least very regular lubrication and is prone to condensation and weld deposits. EP 970 773 B1 describes a central support that is also height-adjustable, ozRfrnn / zznz / E / YiAi, which, however, does not have any drive part for transporting the printed circuit boards. Using reflow soldering, surface-mount devices (SMDs) are soldered onto the surface of printed circuit boards (PCBs) using solder paste. The solder paste, which is a mixture of solder metal granules, flux, and paste components, is applied or printed onto the surface of the PCB for reflow soldering. The components to be soldered are then placed in the solder paste. In the reflow soldering process, the assembly—the circuit board, solder paste, and components—is preheated along the process channel in the preheating zone and heated to a temperature in the soldering zone that is above the melting point of the solder paste. This melts the solder paste, forming the solder joints.In the cooling zone - if there is one - the item to be soldered is cooled until the molten solder solidifies before being removed from the reflow soldering device. In reflow soldering devices, the process channel is covered by a shroud to provide the desired temperature profile and a defined atmosphere within the channel. Additionally, process gases are generated in the process channel, which can be discharged and cleaned. To achieve better results, it is common practice to place a low-pressure or vacuum chamber in the welding area and configure it so that the welding process takes place in the vacuum chamber at a negative pressure well below atmospheric pressure. This ensures that gas and air bubbles, flux residue, and other contaminants are drawn out by the vacuum during the welding process, thus improving the quality of the welded joints. Consequently, the quality of welded joints can be further enhanced by using a hyperbaric chamber within which the welding process takes place. Reflow soldering devices with vacuum chambers are known from patents DE 10 2009 028 865 B4 and DE 10 2019 125 983 A1. Patents DE 201 02 064 U1 and DE 199 11 887 C1 also describe reflow soldering devices that provide a vacuum chamber, having a base portion and a bell-shaped vacuum cover portion that can be raised relative to the base portion. To move the item to be soldered into and out of the vacuum chamber, the cover portion can be lifted from the base portion. BRIEF DESCRIPTION OF THE INVENTION The invention is based on the objective of providing a central support that, on the one hand, reliably transports the element to be welded in the transport direction and, on the other hand, functions reliably in the long term. This problem is solved by a central support with the characteristics of patent claim 1. Accordingly, the base portion is provided to have at least one base portion gear and the drive portion to have at least one drive gear that can be rotatably coupled with the base portion gear, so that the drive gear is rotatably coupled to the drive rollers ozRfrnn / zznz / E / YiAi provided in the drive portion, and so that the drive rollers are in the transport position, in which the base portion gear is rotatably coupled to the drive gear, to support the transport of the welded articles against which the welded articles act. Unlike the prior art, the base section features a driveable sprocket, which is rotationally coupled to the drive sprocket in the drive section. The drive sprocket is thus rotatably coupled to the drive rollers, preferably without the use of a chain. The design is notably lubricant-free. In particular, additional intermediate sprockets may be provided between the drive sprocket and the drive rollers, allowing for the synchronous operation of several drive rollers. The provision of sprockets and rollers has the advantage of not requiring intensive lubrication and is also comparatively resistant to condensation and welding residue. Furthermore, it is advantageous to provide a lowering mechanism between the base and the drive unit, actuated by a rotating drive shaft, to change the drive unit between the transport and lowering positions. This allows the central support to be automatically lowered or raised by actuating the drive shaft. Rotating the drive shaft in one direction moves the drive unit to the transport position; rotating it in the opposite direction moves the drive unit to the lowering position. Advantageously, the lowering mechanism is coupled to the movement of the drive shaft and is also designed so that it can be operated while the central support or welding device is in use. This allows the central support to be moved from the lowered position to the transport position, or vice versa, during operation. It is not necessary to interrupt the welding process for this purpose. Furthermore, it is advantageous that the base and drive sections are configured so that, in the lowered position, the drive gear is rotationally disengaged from the base gear. This has the advantage that, in the lowered position, the drive gear and the drive rollers coupled to it for movement are not driven, but can be stopped. Therefore, if the central support is not required, the drive rollers do not move in the lowered position. The lowering mechanism may comprise at least one rack arranged on the drive portion and extending vertically, and at least one lowering pinion rotatably arranged on the base portion and meshed with the rack, which may be driven by the drive shaft. Consequently, if the drive shaft is rotated in a direction of rotation, the rack moves upward to raise the drive portion or downward to lower it. It is also conceivable that the descent mechanism comprises at least one element of QZRfrnn / zznz / E / YiAi rotation element arranged in the base so that it can rotate about a rotation axis between two rotation positions, wherein the rotation element acts on the drive part at a distance from the rotation axis such that in one rotation position the drive part is in the lowering position and in the other rotation position the drive part is in the transport position. Consequently, by rotating the rotation element, the drive part rises or lowers. In particular, the rotation axis can run transversely to the transport direction or parallel to it. A drive rod can be provided to actuate the rotating element. At one end, this rod acts eccentrically with respect to the axis of rotation of the rotating element, and at the other end, it acts on an eccentric rotatably coupled to the drive shaft. This is possible because, as the drive shaft rotates, the drive rod executes at least one component of movement, causing the rotating element to rotate around the axis of rotation. Therefore, the rotating element can be moved between the two rotational positions by rotating the drive shaft via the drive rod, allowing the drive element to be switched between the lowering and transport positions. This allows the rotating element to be positioned locally away from either the drive shaft or the eccentric, resulting in greater flexibility in component arrangement. In particular, when the central support has a significant longitudinal extension, it is advantageous to provide a synchronizing element that engages with the drive unit at least twice to effect synchronized movement of the drive unit. The synchronizing element may act directly or indirectly on the drive unit. Specifically, it may be implemented as a synchronizing rod or a synchronizing shaft. In this case, two or more synchronously driven rotating elements may be provided. The drive unit then moves synchronously between the lowering and transport positions not just at one point, but at two or more points by means of the synchronizing element. The individual rotating elements can be coupled in motion by means of synchronizing elements. In another configuration, the synchronizing element can be designed as a synchronizing bar, extending in the direction of travel and having a pinion on each of the opposite ends, each of which is provided on the racks of the drive unit. This also allows for forced movement of the drive unit, so that it rises or falls parallel to the direction of travel. Furthermore, it is advantageous that the base section includes a drive shaft housing for a drive shaft extending transversely to the direction of transport to drive the base component wheel. Consequently, the base component sprocket, the drive sprocket, and the drive rollers coupled to it can be driven via the drive shaft or the drive shaft housing. It is also advantageous for the base to include a housing for the drive shaft, where the arrangement is such that the drive shaft extends transversely to the transport direction. The drive shaft then runs parallel to the drive shaft. The drive section can be raised or lowered by rotating the drive shaft. The base can be provided within a frame of a transport unit for carrying the welded element along the transport direction. In particular, the transport unit can be configured to carry the element to be welded in parallel free lateral zones in the transport direction. The central support is preferably provided in the central area of ​​the transport unit or its frame. The objective mentioned at the beginning is also achieved by means of a transport unit for transporting elements to be welded along a transport direction through at least one zone of a welding device, wherein the transport unit comprises a central support according to the invention. The objective mentioned at the beginning is also achieved by means of a soldering device, in particular, a reflow soldering device for continuous soldering of assembled printed circuit boards or a drying device for drying assembled printed circuit boards, with the features of claim 13. The element to be soldered is transported through the device in a process channel along a transport direction, wherein the process channel includes at least one zone, in particular a preheating zone, a soldering zone, and preferably also a cooling zone. A transport unit according to the invention and / or a central support according to the invention is provided in at least one zone. It is particularly preferred that the welding area include an opening pressure chamber, wherein the pressure chamber contains a transport unit according to the invention and / or a central support according to the invention. The pressure chamber may have a base portion and a cover portion that can be raised relative to the base portion when the welding device is in operation. Such a welding device—without a central support according to the invention—may in particular be a welding device as shown in the applicant's document DE 10 2019 125 983 A1. For opening and closing the pressure chamber, it may also be provided with doors, slides, gates, or similar features instead of the liftable cover portion. This development has the advantage that the central support can be changed between the transport position and the lowering position via a corresponding control without opening the pressure chamber and / or without stopping the transport of the element to be welded. BRIEF DESCRIPTION OF THE FIGURES Further details and advantageous configurations of the invention can be found in the following description, on the basis of which exemplary embodiments of the invention are described and explained in more detail. It shows: Figure 1 a side view of a reflow soldering device; Figure 2 The reflow soldering device according to Figure 1 in a front view; Figure 3 top view of a part of the soldering area of ​​the reflow soldering device without a protective cover; Figure 4 an symmetrical view of a side wall of a central auxiliary conveyor located in the welding zone of Figure 3; Figure 5 shows the central support according to Figure 4 in an enlarged view; Figure 6 the rear of the central support according to figure 5; Figure 7 an enlarged view of the descent mechanism 110 of Figure 5; Figure 8 a view according to Figure 7 with a reduced number of parts; Figure 9a a cross-section through another transport device with central support in the transport position; Figure 9b the transport unit according to figure 9a in the descending position; Figure 10a the central support according to figure 9a in a side view in transport position; Figure 10b shows the transport unit according to Figure 10a in the descending position; Figure 11a the central support according to figure 10a without cover in transport position; and Figure 11b shows the transport unit according to Figure 11a in the lowering position; and Figure 12 shows the lowering mechanism of the central support of the transport unit according to Figures 9a and 9b. DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a welding device 10 in the form of a reflow welding device for the continuous welding of elements to be welded. The welding device 10 has an inlet 12 and an outlet 14, wherein the element to be welded enters the welding device 10 through the inlet 12 and exits the welding device 10 through the outlet 14. The element to be welded is transported through the welding device 10 along a transport direction 18 of a process channel 16 indicated in Figure 1. In the process channel 16, a preheating zone 20, a welding zone 22, and a cooling zone 24 are provided. In the case of the welding device 10 shown in Figure 1, a machine cover 25 with three sections 26, 28, and 30 is provided to cover the process channel 16. As can be seen from Figures 1 and 2, a communication unit 36 ​​is provided with a display and an input device, through which communication with a welding machine control 10 can take place. The item to be soldered, i.e., the printed circuit board (PCB) coated with solder paste and assembled with electronic components, or a carrier that holds one or more PCBs, is first heated in preheating zone 20 to a temperature below the melting point of the solder paste. In soldering zone 22, the PCB is heated to a process temperature for a specific time period, above the melting point of the solder paste, so that it melts in the soldering zone to bond the electronic components to the PCB. The item to be soldered is then cooled in cooling zone 24 to allow the liquid solder to solidify before it is removed from outlet 14 of the soldering device 10. Within the soldering device 10, a transport system 34 and a transport unit 50 are provided to transport the printed circuit boards along the transport direction 18. As can be seen from the front view in Figure 2, the cover 25 can be rotated about a rotation axis 32 that extends parallel to the transport direction 18. The transport system 34 can be accessed by rotating the cover 25 for visual inspection, maintenance, cleaning, setup, replacement, and, if necessary, repair. In the welding zone 22 there is a pressure chamber in the form of a vacuum chamber 40, which is formed by a base piece 42 represented in the plan view according to figure 3 and a cover piece, not represented in the figures, with which the base piece 42 can be closed. When the soldering device 10 is in operation, the cover portion can be lifted from the base portion 42 by means of a lifting mechanism. Lifting the cover portion is necessary to move the printed circuit boards into the vacuum chamber 40. As soon as the printed circuit boards are in the vacuum chamber 40, the cover portion is lowered so that it rests on the base portion 42. In a subsequent step, the vacuum chamber 40 is emptied using a vacuum pump (not shown), creating a suitable vacuum. Due to the negative pressure, air inclusions in the solder are expelled. After a brief application of negative pressure to the vacuum chamber 40, the cover portion is lifted by a corresponding activation of the lifting mechanism, allowing the printed circuit boards to exit the vacuum chamber 40.Advantageously, the printed circuit boards move through the vacuum chamber 40 within the described process at a constant or variable speed. The plan view according to Figure 3 schematically shows the base portion 42 of the pressure chamber 40 and the transport unit 50 arranged in the base portion 42. The vacuum chamber 40 provides a chamber inlet 62, where circuit boards coming from the transport system 34 are transferred to the transport unit 50, and a chamber outlet 64, where the circuit boards are transferred back to the transport system 34. In Figure 3, a solderable element 170 emerging from the chamber outlet 64 is shown with dashed lines in the form of an assembled printed circuit board. The transport unit 50 preferably has a rectangular frame 51 that can be inserted into the pressure chamber 40. Transport elements 168 are preferably arranged on the right and left of the frame 51, running parallel to the transport direction 18, which transport the element to be soldered 170 through the pressure chamber 40 in the area of ​​the free longitudinal edges running parallel to the transport direction 18. In addition, a central support 66 is fixed to the frame 51. Correspondingly, the transport systems 34 also have transport elements (not shown) parallel to the transport direction 18 for transporting the printed circuit boards at their free longitudinal edges, as well as central supports 68. The central support 66 and a side wall 70 of the pressure chamber 40 or process channel are shown in Figure 4. Also shown in Figure 4 is a drive shaft 72, which extends through the side wall 70 in a pressure-sealed manner. The free end 74 of the drive shaft 72 can be rotated by means of a lifting drive 76 arranged outside the pressure chamber 40 around the longitudinal axis of the drive shaft 72 at a drive angle of, for example, 40° to 80°. As is particularly clear from Figures 5 and 6, the central support 66 has a base portion 80 and a drive portion 82. The drive portion 82 is shown in Figures 4, 5, and 6 in a lowered position. However, as described later, the drive portion 82 can be raised from the lowered position to a transport position by rotating the drive shaft 72, where it acts against the element to be welded 170 during the operation of the central support for transporting the element to be welded 170. The side wall 70 provides further openings 77, 78 through which other shafts can be guided out of the pressure chamber 40 in a pressure-sealed manner. A drive shaft 79, shown in Figure 6, can be passed through opening 78, for example, to transport the welding element 170, as described below. For example, a driveable center support adjustment shaft can be passed through shaft opening 77, which interacts with a rotating support 81 provided in the base portion 80. The arrangement can be such that the position of the center support 66 can be adjusted parallel to the transport direction 18 by rotating the center support's generating shaft. A base gear 84 is rotatably mounted on the base portion 80 and has a drive shaft housing 86 in the form of a hexagonal opening. A drive shaft 79, shown in Figure 6, can be inserted into the drive shaft housing 86. Consequently, when the drive shaft 79 is rotated, the base gear 84 rotates. An intermediate gear 88 is rotatably coupled to the base gear 84 and, in turn, meshes with a drive gear 90. The drive gear 90 is rotatably mounted on the drive portion 82. As is clear from Figure 6, the intermediate gear 88 is movably connected to the base portion 80 by a first rocker arm 92 and to the drive portion 82 by a second rocker arm 94. The connection is such that the intermediate gear 88 meshes with the gear 84 of the base portion on one side and with the drive gear 90 on the other side, even when the drive portion 82 is raised relative to the base portion 80. As is particularly clear from Figure 6, the drive gear 90 meshes with two pinions 96, each of which is mounted on a shaft, each of which is rotatably coupled to a drive roller 98, which can be seen clearly in particular in Figure 5. The pinions 96 are in turn rotationally coupled to the intermediate gears 100, which are in turn rotationally coupled to the pinions 102. The shafts are driven via pinion 102 and are rotationally coupled to other drive rollers 104. In general, all the drive rollers 98 and 104 are rotatably coupled to each other, so that when the gear 84 of the base portion rotates, the drive rollers 104 rotate accordingly. To move the drive part 82 between the transport position and the lowering position, a lowering mechanism 110 is provided, which can be seen in particular in Figure 5. The lowering mechanism 110 can be actuated via the drive shaft 72. If the drive shaft 72 is rotated counterclockwise, the drive part 82 is raised to the transport position; if, starting from the transport position, the drive shaft 72 is rotated clockwise, the drive part 82 is transferred to the lowered position shown in Figure 5. The lowering mechanism 110 shown in Figures 7 and 8 comprises a rotating element 112 rotatably mounted on the base portion 80 about a rotation axis 114 running transversely to the transport direction 18. The rotating element 112 engages, via a coupling screw 116, with the drive portion 82 or with a downwardly extending drive portion 118 of the drive portion 82. For this purpose, the plate-shaped drive portion 118 extension has a connecting groove 140 to accommodate the connecting screw 116 shown in Figure 8. As shown in Figure 7, the lowering mechanism 110 also has a drive shaft housing 124 provided in the base portion 80, in which a rotationally coupled eccentric 126 is arranged. A drive rod 128 acts on the eccentric 126 eccentrically to the axis of rotation of the drive shaft 72. At the end of the drive rod 128 opposite the eccentric 126, the eccentric is coupled to the rotating element 112 eccentrically with respect to the axis of rotation 114 to rotate the latter. For this purpose, the drive rod 128 is rotatably mounted on the eccentric side with a screw 130 to the eccentric 126 and on the rotating element side with a screw 132 to the rotating element 112. If, as shown in Figure 7, the drive shaft 72 is rotated counterclockwise (arrow 134), the drive bar 128 moves parallel to it due to the motion coupling, so that the rotating element 112, corresponding to the eccentric 126, rotates clockwise around the rotating axis 114 (arrow 136). Consequently, the coupling screw 116 rotates upwards along arrow 138 from the first pivoted position shown in Figure 7, so that the extension of the drive part 118, and therefore the drive part 82, along arrow 120, moves vertically upwards to the raised transport position. In Figure 8, the drive extension 118 is shown without the rotating element 112 and the drive rod 128. The connecting slot 140 of the drive extension 118, into which the coupling screw 116 fits, is visible. When the rotating element 112 rotates counterclockwise, the coupling screw 116 moves according to arrow 138 around the axis of rotation 114. The coupling screw 116 acts against the upper edge of the slot 142, resulting in the extension being raised. QZRfrnn / zznz / E / YiAi drive part 118. As it continues to rotate, the coupling screw 116 migrates along the edge of the upper groove 114 of the link groove 140 from the right outer position of the link groove 140 shown in Figure 8 toward the center area or the left end area of ​​the link groove 140. To ensure purely vertical movement of the drive part extension 118 and, consequently, of the drive part 82, a guide pin 144 is provided in the drive part extension 118, fitting into a vertical groove 146 provided in the base part 80. As a result, when the rotating element 112 is turned, the drive part extension 118 is forcibly guided vertically upwards until the drive part 82 reaches the transport position. To move the drive part 82 from the transport position to the lowering position, the drive shaft 12 is rotated backward clockwise according to the described movement sequence, thereby moving the drive rod 128 to the right and then rotating the rotating element 112 clockwise. As a result, the coupling screw 116 moves downward in its circular path around the rotating axis 114, forcing the extension of the drive part 118 to move vertically downward until the drive part 82 is in the lowering position. As shown in Figure 5, alongside the rotating element 112, another rotating element 150 is provided in the base portion. The rotating element 150 can be rotated about a rotating axis 114 and, in conjunction with the rotating element 112, drives a coupling screw 116. This screw then serves to secure another extension of the drive portion 152, which is constructed according to the extension of the drive portion 118, for raising to the transport position or lowering to the lowering position. A synchronizing rod 154 is provided to synchronize the movements of the two rotating elements 112 and 115. The free ends of the synchronizing rod 154 are fixed to the two rotating elements 112 and 150 by means of screws 156 eccentric to the respective rotating axis 114.The distance between the screws 156 and the respective rotation axes 114 corresponds to the distance 122 between the respective rotation axis 114 and the respective associated coupling screws 116. In general, synchronized movement of the two extensions of the drive part 118 can be achieved, and therefore movement of the drive part 82 along its entire longitudinal extension, when the drive shaft 72 is rotated. Depending on the longitudinal extension of the central support 66, more than two rotating elements 112, 150 can also be used, which are then coupled together for movement via the corresponding synchronizing bars 154. The central support shown in Figures 4 to 8 is intended for use in a pressure chamber as shown in Figure 3. The described central support 66 is very robust, and due to the use of gears or pinions, it can preferably be driven without lubricant and is located between the lowering position and the transport position, adjustable during operation via the drive shaft 72 and the associated lowering mechanism 110 between the transport position and the lowering position. QZRfrnn / zznz / E / YiAi Figures 9a to 12 show another form of a central support 166, which can be used in the pressure chamber 40 shown in Figure 3, the transport unit 50 and / or a transport system 34 according to Figure 3. Figure 9a shows a cross-section of a transport unit 50 having lateral transport elements 168, which can be configured, for example, as actuatable drive rollers, by means of which the element to be welded 170 is transported in the transport direction in the area of ​​the opposing longitudinal edges 172. In the central area between the transport elements 168, a central support 166 is provided, which supports the respective element to be welded 170 or the respective printed circuit board in the transport position in the central area. In Figure 9a, the central support 166 is shown in its transport position, in which it acts against the respective element to be welded 170. In Figure 9b, the central support 166 is shown in its lowering position, in which it does not act against the respective element to be welded 170. Figure 10a shows a side view of the central support 166 in the transport position. The central support 166 has a base portion 174 and a drive portion 176, in which drive rollers 178 are provided and can be driven. The drive portion 176 with the drive rollers 178 can be moved from the transport position shown in Figure 10a to the lowered position shown in Figure 10b. The movement takes place vertically by a lowering distance 180. Figures 11a and 11b, which show a longitudinal section through the central support 160, show that a base gear 84 is provided in the base portion 174, meshing with a drive gear 90 in the transport position. Downstream of the drive gear are intermediate gears 100, which ultimately drive pinions 102. These pinions are non-rotatingly arranged with the drive rollers 178 on a shaft. Intermediate gears 100 are provided between the pinions 102 according to the design based on the central support 66. Corresponding to the design shown in Figure 6, the base portion gear 84 has a housing 86 for the drive shaft, into which a drive shaft (not shown in Figures 9a to 12) fits. The design is such that when the drive portion 176 is switched to the lowering position, the drive gear 90 moves vertically downwards and, as shown in Figure 11b, the base portion gear 84 is rotationally disengaged from the drive gear 90. This configuration has the advantage that the drive rollers 178 are not driven in the lowering position. Consequently, the drive rollers 178 remain stationary in the lowering position. Preferably, the arrangement is such that when the drive portion 176 is switched to the transport position, the base gears 84 automatically mesh with the drive gears 90. The lowering mechanism 110 for the drive portion 176 is shown in Figure 12. A vertically extending rack 182 is provided in the drive portion 176. A lowering pinion 184 is provided in the base portion 174, which provides a drive shaft receptacle 124 for receiving a drive shaft, not shown in Figures 9a to 12. By rotating the drive shaft that runs transversely to the transport direction, the drive part 176 can be raised to the transport position or lowered to the lowering position. To ensure synchronous movement of the drive unit 176 along its longitudinal extension 5, a rotatably mounted synchronizing shaft 186 may be provided in the base portion 174. The synchronizing shaft 186 may be rotatably supported by two bearing blocks 187. As shown in Figure 12, the synchronizing shaft 186 has a pinion 188 at each of its free ends, which meshes with a rack section 190 provided in the drive unit 176 and extending vertically. In this way, in particular, synchronized and jam-free raising and lowering of the longitudinal extension of the drive unit 176 can be ensured.

Claims

1. A central support (66, 166) for supporting elements to be welded (170) during transport along a transport direction (18) through a welding device (10), wherein the central support (66, 166) has a base portion (80, 174) and a drive portion (82, 176) adjustable in height with respect to the base portion (80, 174), wherein the drive portion (82, 176) can be adjusted between a transport position in which it acts against the element to be welded (170) and a lowering position in which it does not act against the element to be welded (170), characterized in that the base portion (80, 174) has at least one toothed wheel and the drive portion (82, 176) has at least one drive toothed wheel (90) that can be rotationally engaged with the toothed wheel. from the base part (84), so that the drive gear (90) is rotatably coupled to the drive rollers (104,178) provided in the drive portion (82, 176), and because the drive rollers (102, 178) act against the element to be welded (170) to assist in transporting the element to be welded (170) in the transport position in which the sprocket of the base portion (84) is rotatably coupled to the drive sprocket (90).

2. The central support (66, 166) according to claim 1, further characterized in that between the base part (80, 174) and the drive part (82, 176) there is a lowering mechanism (110) that can be actuated by means of a rotating drive shaft (72) to move the drive part (82, 176) between the transport position and the lowering position.

3. The central support (66, 166) according to claim 2, further characterized in that the lowering mechanism (110) is coupled to the drive shaft (72) for movement and is designed so that it can be actuated during the operation of the central support (66, 166).

4. The central support (66, 166) according to claim 2 or 3, further characterized in that the base part (80, 174) and the drive part (82, 176) are designed such that in the lowering position the drive gear (90) is rotationally decoupled from the gear of the base part (84).

5. The central support (66, 166) according to claim 2, 3 or 4, further characterized in that the lowering mechanism (110) comprises at least one rack (182) provided in the drive portion (82, 176) and extending vertically and at least one lowering pinion (184) rotatably arranged in the base (80, 174) and meshing with the rack (182), which can be driven by the drive shaft (72).

6. The central support (66, 166) according to claim 2, 3 or 4, further characterized in that the lowering mechanism (110) comprises at least one rotating element (112, 150), which is arranged in the base part (80, 174) in such a way that it can rotate about a rotation axis (114) between two rotation positions, wherein the rotating element (112, 150) acts on the drive part (82, 176) at a distance from the rotation axis (114), so that in one rotation position the drive part (82, 176) is in the lowering position and in the other rotation position the drive part (82, 176) is in the carrying position.

7. The central support (66, 166) according to claim 6, further characterized in that a drive bar (128) is provided, which, at one end, acts eccentrically to the rotation axis (114) on the rotation element (112, 150) and, at the other end, acts on an eccentric (126) coupled in rotation to the drive axis (72).

8. The central support (66, 166) according to one of the preceding claims, further characterized in that a synchronizing element (154, 186) is provided which acts on the drive part (82, 176) at at least two points to effect the synchronized displacement of the drive part (82, 176).

9. The central support (66, 166) according to one of the preceding claims, further characterized in that the base part (80, 174) has a drive shaft housing (86) for a drive shaft (79) for driving the gear wheel of the base part (84).

10. The central support (66, 166) according to any one of claims 2 to 9, further characterized in that a drive shaft housing (124) is provided in the base part (80, 174) for the drive shaft (72), wherein the arrangement is such that the drive shaft (72) extends transversely to the transport direction (18).

11. The central support (66, 166) according to one of the preceding claims, further characterized in that the base part (80, 174) is provided in a frame (51) of a transport unit (50) for transporting the element to be welded (170) along the transport direction (18).

12. A transport unit (50) for transporting elements to be welded (170) along a transport direction through at least one zone (20, 22, 24) of a welding device, characterized in that it comprises a central support (66, 166) in accordance with any of the preceding claims.

13. A welding device (10) in which the element to be welded (170) can be transported along a transport direction (18) through at least one zone (20, 22, 24), characterized in that at least one of the zones (20, 22, 24) is provided with a transport unit (50) according to claim 12 and / or a central support (66, 166) according to one of claims 1 to 11.

14. The welding device (10) according to the preceding claim, further characterized in that an area is designed as a welding area (22) in which an openable pressure chamber (40) is provided, and in that a transport unit (50) according to claim 12 and / or a central support (66, 166) according to any one of claims 1 to 11 is provided in the pressure chamber (40).

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