Soldering device, in particular reflow soldering device, having a cover and a switchable suction channel

Abstract

Disclosed is a soldering device for continuously soldering printed circuit boards along a conveying direction, in particular a reflow soldering device, comprising an inlet and an outlet for supplying and removing printed circuit boards, a process channel comprising a preheating zone, a soldering zone and / or a cooling zone, a main body and at least one cover that can be shifted between a closed position and an open position, the cover surrounding a hood chamber, the hood chamber being located above the process channel, a fan motor being arranged in the hood chamber, a central suction channel being arranged in the hood chamber, a first suction element connected to the suction channel being arranged in the hood chamber, the first suction element sucking hood air from the hood chamber, a second suction element being arranged in the hood chamber connected to the suction channel, the second suction element sucking process gas from the process channel, a switching device being arranged, the switching device being constructed to switch between an operating mode and a cooling mode, in which the hood air is sucked via the first suction element in the operating mode, and in which the process gas is sucked via the second suction element in the cooling mode.

Description

Technical Field

[0001] The invention relates to a soldering device, in particular a reflow soldering device, for continuously soldering printed circuit boards along a conveying direction, comprising a process channel including a preheating zone, a soldering zone and / or a cooling zone, having a main body and a cover, wherein the cover can be shifted between a closed position and an open position, in which the process channel is closed, and in which the cover is open and the process channel is accessible. The cover surrounds a cover chamber, which is located above the process channel, and in which a fan motor is particularly arranged. Background Art

[0002] By means of a reflow soldering device, so-called SMD components (surface mounted devices) are soldered to the surface of a printed circuit board with the aid of a solder paste. In particular, a solder paste of a mixture of solder metal particles, flux and paste components is applied or printed on the surface of the printed circuit board for reflow soldering. The components to be soldered are then set into the solder paste. In the reflow soldering process, the soldering material (i.e., the assembly consisting of the printed circuit board, solder paste and components to be soldered) is preheated in a preheating zone along a process channel, and the material is heated to a temperature above the melting point of the solder paste in the soldering zone. As a result, the solder paste melts and forms a solder joint. In the cooling zone, if present, the material is cooled until the molten solder solidifies before the soldering material is removed from the reflow soldering device.

[0003] DE 10 2019 128 780 A1, DE 10 2019 125 981 A1 and DE 10 2005 055 283 A1 describe soldering devices for continuous soldering of printed circuit boards. Other soldering devices are known from DE 10 2020 132 792 A1, JP 2003-71562 A and KR 10 2010 005 3730 A.

[0004] In the case of a reflow soldering device, the process channel is usually formed by two channel halves, namely an upper channel half and a lower channel half. The lower channel half is arranged in or on the main body, and the upper channel half is arranged in or on the cover. Other components (such as nozzle plates, fan units, air channels for guiding process gases, filter elements and / or cooling elements) are usually arranged in or on the process channel, or in or on the main body, and in or on the cover. In short, the desired temperature distribution is thus provided in the process channel along the conveying direction, wherein the process gas is blown into the process channel, sucked from the channel, cooled, cleaned and sent back to the process channel, especially in the cooling zone.

[0005] In particular, when a change in the welding material is about to occur, the desired target temperature distribution in the welding device must be adapted to the changed parts to be welded. In this case, it may be necessary to reduce the temperature in the welding device, in particular the temperature in the welding zone, as quickly as possible. For this purpose, it is known to open the cover so that the components forming and surrounding the process channel, in particular the channel halves, the nozzle plate, the conveying system, the heating element and the fan motor and / or the air channel cool to the ambient temperature. However, it is disadvantageous that hot process gases flow out of the welding device, thereby generating a high heat input into the space around the welding device, in particular into the production hall. In addition, cooling also takes a considerable amount of time and is associated with a high noise level. In addition, harmful process gases may enter the space around the welding device, in particular into the production hall. Summary of the invention

[0006] The object of the invention is to provide a welding device in which a change in the temperature distribution can be achieved in a simple manner without the above-mentioned disadvantages occurring.

[0007] This object is achieved by a welding device having the features of solution 1. Therefore, in particular, it is provided that a central suction channel is arranged in the hood chamber, wherein a first suction element connected to the suction channel is arranged in the hood chamber in the region of the fan motor, the first suction element is used to suck the hood chamber air, a second suction element connected to the suction channel is arranged in the hood chamber, the second suction element is used to suck the process gas from the process channel, and a switching device is arranged and designed, the switching device is used to switch between an operating mode and a cooling mode, in which the hood chamber air is sucked via the first suction element, and in which the process gas is sucked via the second suction element.

[0008] By switching between operating mode and cooling mode and by providing a first suction element and a second suction element, a welding device for welding welding material can be operated in operating mode when the cover is closed. In this case, the first suction element draws the hood air heated by the motor from the hood. If the welding device is to be cooled quickly after a production cycle is completed, the welding device can be switched to cooling mode by drawing hot process gas from the process channel via the second suction element in order to cool the process channel.

[0009] Here, the central suction channel has a dual function: on the one hand, in operating mode, the hood chamber in which the fan motor is arranged is ventilated and thus cooled. On the other hand, in cooling mode, hot process gases are discharged from the process channel via the mode, whereby rapid cooling of the process channel can be achieved. Since the welding device is not opened in cooling mode, the sucked hot gases can be discharged via a corresponding exhaust device or can also be adjusted so that they can be discharged into the ambient air at a suitable temperature and cleaned accordingly. The provision of a central suction channel also has the advantage that, in particular in cooling mode, hot process gases can be sucked out of the welding device at a high rate, in particular over the entire longitudinal extent of the welding device. The suction channel is particularly dimensioned so that sufficient gas can be sucked from the welding device to achieve a corresponding rapid cooling.

[0010] It is further advantageous if a third suction element is provided and the switching device is configured such that in operating mode, process gas is sucked from the region of the inlet and / or outlet via the third suction element and in cooling mode no process gas is sucked via the third suction element. Thus, the switching device opens or switches or closes not only the first and second suction elements but also the third suction element. In operating mode, the third suction element is opened together with the first suction element and is closed together with the first suction element in cooling mode.

[0011] Advantageously, the suction channel extends approximately parallel to the conveying direction and is designed to strengthen the cover. The central suction channel thus has an additional function: in operating mode and cooling mode, the chamber air or process gas can be centrally sucked from the welding device and, in addition, the central suction channel serves to stabilize and strengthen the cover.

[0012] It is further advantageous if the first suction element is designed as a suction pipe with a suction opening, wherein the suction opening is arranged in the lower region of the cover and in the region of the fan motor.

[0013] It is further advantageous if the second suction element is designed as a suction tube with a suction opening, wherein the suction opening is located in the region of the process channel in the closed position of the cover.

[0014] Suction pipe can have the mouth of a pipe leading to the central suction passage separately. In addition, suction pipe can have at least one suction port that is arranged in the cover chamber separately. By suction pipe being set, therefore suction port can be arranged in the efficient position of suction.

[0015] It is conceivable that the first suction element has a portion extending approximately horizontally and / or transversely to the conveying direction in the closed position of the cover, which has a plurality of suction openings in its longitudinal extent. This enables large-area suction to be achieved in the cover chamber.

[0016] Furthermore, it is advantageous to provide a plurality of second suction elements, whose suction openings are located in the region of the process channel or open into the process channel in the closed position of the cover. Thus, the suction openings can intervene in or adjoin the process channel in order to extract hot process gas from the process channel. In particular, it is conceivable that the suction openings of the second suction elements are connected to the respective zones and / or are spread out between two nozzle plates located in the process channel in order to achieve efficient and uninterrupted suction.

[0017] In the closed position of the cover, the second suction element preferably can have an end extending substantially vertically, which has an open free end arranged in or adjacent to the process channel. This design has the advantage that the vertical portion can be arranged so that the function of the single zone is not weakened.

[0018] In addition, it is advantageous that the nozzles of the first suction element and the nozzles of the second suction element in each case are adjacent to each other and that the switching device includes and / or operates a closing element so that in the operating mode, the closing element closes the nozzle of the second suction element and in the cooling mode closes the nozzle of the first suction element. Here, the central suction channel can have a triangular or polygonal cross-section with adjacent channel walls. Advantageously, a quadrilateral cross-section with four channel walls will be provided. In addition, it is advantageous that the nozzles of at least two suction pipes are arranged on adjacent walls. The planes of the corresponding nozzles then enclose an angle, which is a right angle in the case of a rectangular cross-section of the suction channel. In addition, it is advantageous that a closing element is provided in the suction channel, which closes one nozzle in the first position and closes another nozzle in the second position.

[0019] The closing element is preferably designed as a pivot flap which can be pivoted between respective positions about a pivot axis which preferably extends parallel to the conveying direction.

[0020] In this case, it is advantageous if the switching device comprises or operates a controllable actuator and an adjustment mechanism via which several closing elements can be adjusted together. It is conceivable that the actuator is driven pneumatically or electrically and that a lifting device and / or a drive shaft are provided as an adjustment mechanism via which a plurality of pivoting flaps can be pivoted into the corresponding position. For example, all flaps located in the area of ​​a welding device can be moved synchronously.

[0021] The third suction elements are arranged in particular at the inlet 12 and the outlet 14 of the welding device and are designed in particular as suction chambers.

[0022] It is further advantageous to provide a suction element which can be switched between an open position and a closed position and which can be switched or controlled by a switching device so that in the operating mode the suction element is closed and in the cooling mode the suction element is open, whereby in the cooling mode ambient air can flow into the welding device. Thus, in the cooling mode sufficient fresh air can flow from the environment into the machine in order to cool the process channel or associated components.

[0023] As mentioned at the outset, it is advantageous to provide a suction device connected to the suction channel and to be configured to suction the process gas in the operating mode and in the cooling mode. The suction device can be integrated into the welding device or can be implemented as a device arranged separately therefrom. It is further advantageous to provide a cooling and / or cleaning device for cooling and / or cleaning the process gas sucked via the suction channel. The cooled and cleaned process gas can then be discharged into the environment of the welding device.

[0024] In order to form the hood chamber, it is particularly advantageous if the cover comprises a frame structure with door-shaped frame legs extending transversely to the conveying direction, wherein the frame legs each have a first support portion pointing toward the hood axis and a second support portion pointing vertically downwards and a central portion arranged between the support portions, about which the cover hood can be pivoted, and wherein the suction channel is arranged on the frame legs. Overall, this results in an advantageous reinforcement of the cover hood. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further details of the invention can be found in the following description, based on which exemplary embodiments of the invention are described and explained in more detail.

[0026] The accompanying drawings show:

[0027] Figure 1 shows a side view of a reflow soldering apparatus tilted from the front with a closed cover hood and a closed hood flap;

[0028] Figure 2 Shown according to Figure 1 A front view of a reflow soldering apparatus with an open cover and an open cover flap;

[0029] Figure 3 Shown is the view from the front. Figure 1 A reflow soldering device having an opened cover and an opened cover flap;

[0030] Figure 4 Shown is the view from the rear. Figure 1 A reflow soldering device having an opened cover and an opened cover flap;

[0031] Figure 5Shown is the view from the front. Figure 1 A reflow soldering device without a machine panel;

[0032] Figure 6 A cover with a central suction channel and no panels is shown;

[0033] Figure 7 A cross section of the central suction channel transverse to the conveying direction is shown;

[0034] Figure 8 shows a section through the third suction element transversely to the conveying direction; and

[0035] Fig. 9 The closable suction element is shown as a separate part. DETAILED DESCRIPTION

[0036] Figure 1 A reflow soldering device 10 for continuously soldering materials for soldering is shown. The reflow soldering device 10 has an inlet 12 and an outlet 14, wherein the soldering material enters the reflow soldering device 10 via the inlet 12 and is discharged from the reflow soldering device 10 via the outlet 14. In this case, the soldering material is transported along a transport direction 18 through the reflow soldering device 10. Figure 1 The process channel 16 is shown.

[0037] A preheating zone 20, a welding zone 22 and a cooling zone 24 are provided in the process channel 16. Figure 1 In the illustrated reflow soldering device 10 , a cover 25 having two cover flaps 26 , 28 is provided for covering a hood chamber 30 enclosed by the cover 25 , in which the upper channel half of the process channel 16 is located.

[0038] As from Figure 1 and Figure 2 As can be seen in FIG. 1 , a communication unit 36 ​​having a screen and input means is provided, via which communication unit 36 ​​a machine controller of the reflow soldering device 10 can be communicated with.

[0039] The soldering material (i.e., the printed circuit board provided with solder paste and filled with electronic components) is first heated to a temperature below the melting temperature of the solder paste in the preheating zone 20. In the soldering zone 22, the printed circuit board is heated for a certain time to a process temperature, which is higher than the melting point of the solder paste, so that the solder paste melts in the soldering zone to solder the electronic components to the printed circuit board. In the cooling zone 24, the soldering material is cooled so that the liquid solder solidifies before the soldering material is removed at the outlet 14 of the reflow soldering device 10.

[0040] A conveyor system 34 is provided in the reflow soldering system 10 for conveying the printed circuit boards along a conveying direction 18 .

[0041] As from Figure 2 As can be seen in the figure, the cover 25 can be pivoted open about a cover axis 32 extending parallel to the conveying direction 18. By pivoting open the cover 25, the interior of the process channel 16 and the conveying system 34 become accessible so that they can be visually inspected, maintained, cleaned, set, replaced and, if necessary, repaired.

[0042] As from Figure 2 As can be seen further in the drawing, the hood flap 26 can be pivoted open about a flap axis 38 extending parallel to the hood axis 32. By pivoting the hood flaps 26, 28 open, the hood chamber 30 above the process channel and thus the hood chamber 30 above the upper channel half becomes accessible, wherein, as further shown below, in particular, a fan module 50, a heating element and an air channel are provided. Figure 2 It can also be seen in FIG. 1 that the flap axis 38 is arranged vertically above the hood axis 32 both when the hood 25 is open and when the hood 25 is closed.

[0043] The welding device 10 has two longitudinal sides 42 and 44 and two narrow sides 46 and 48. Figure 2 It can be clearly seen in FIG. 3 that the hood axis 32 is located in the region of a rear longitudinal side 44 . In contrast, the flap axis 38 is located in the region of the front longitudinal side 42 or is closer to the front longitudinal side 42 than to the rear longitudinal side 44 .

[0044] exist Figure 3 2, wherein the cover 25 on the one hand and the cover flaps 26, 28 on the other hand are open, in particular the open process channel 16 can be seen. The process channel 16 is formed by two channel halves, namely an upper channel half and a lower channel half. The lower channel half with the lower nozzle plate 40 is arranged in or on the body 60, while the upper channel half with the upper nozzle plate 40 is arranged in or on the cover 25. The upper channel half, the upper nozzle plate 40 and the other components located in the cover chamber 30 are arranged on the cover 25 so that they are also pivoted open when the cover 25 is open and the process channel 16 is not covered.

[0045] As from Figures 2 to 4 As is clear from the drawing, this arrangement ensures that when the cover 25 is open, the process channel 16 is accessible from the front longitudinal side 42 and the upper hood chamber 30 covered by the hood flaps 26 , 28 is accessible from the other rear longitudinal side 44 .

[0046] This has the advantage, among other things, that when the cover 25 is open and thus when the process channel 16 is uncovered, the gas flowing out of the process channel 16 does not flow into the upper hood chamber 30 covered by the hood flaps 26, 28. In addition, several operators can monitor or maintain the process channel 16 simultaneously and independently of the hood chamber 30 covered by the hood flaps 26, 28.

[0047] As from Figure 4 and Figure 5 As is clear from the figure, a plurality of fan modules 50 with fan motors 51 are located above the upper channel half in the hood chamber 30 covered by the hood flaps 26, 28, which are provided for generating a provided air flow in the process channel 16. The fan modules 50 can additionally have heating elements in order to provide a predetermined temperature, in particular in the preheating zone 20 and the process zone 22. By means of the fan modules 50 or their fan motors 51, a correspondingly heated process gas is introduced through the nozzle plate 40 towards the welding material.

[0048] Therefore, if the cover 25 is open, the process channel 16 and the conveying system arranged therein can be particularly accessible. If the cover flaps 26, 28 are open, the fan motors 51 arranged therein and their heating elements and the air channels arranged therein can be particularly accessible.

[0049] exist Figure 1 In their closed position shown, the two cover flaps 26, 28 have a horizontal portion 52, which is located close to the flap axis 38 and extends approximately in the horizontal direction. This horizontal portion is adjacent to an inclined portion 56, which is away from the flap axis 38 and encloses an obtuse angle 54 with the horizontal portion 50. Figure 4 As is clear from the figure, the handle 58 for opening the two cover flaps 26, 28 is arranged on the inclined portion. Figure 2 Clearly seen in.

[0050] The main body 60 stands on the base plate by means of feet 62. The feet 62 are provided on the lower frame 64. In addition, a drive unit 66 for electrically opening and closing the cover 25 is provided, and the drive unit is supported on the lower frame 64 at one end and on the cover 25 at the other end. Figure 5 It is also clear that the cover 25 comprises gate-shaped frame arms 68, each of which has a first support portion 70 directed towards the cover axis 32 and a second support portion 72 directed towards the respective drive unit 66. A central portion 74 is provided between the two support portions.

[0051] As from Figure 6 As is clear from the drawing, a central suction channel 100 is provided in the cover 25 over the longitudinal extent of the welding device 10. The suction channel 100, which has a rectangular cross section, is fastened to the frame arms 68 or connects the frame arms 68 to one another. Here, the suction channel 100 is arranged in the region of the support part 72 that is remote from the cover axis 32. The suction channel 100, which extends approximately parallel to the conveying direction 18, reinforces the cover 25.

[0052] The suction channel 100 has a plurality of first suction elements 104, a plurality of second suction elements 106 and two third suction elements 108. The first suction element 104 and the second suction element 106 are designed as suction tubes. The two third suction elements 108 are each arranged at the inlet 12 and the outlet 14 of the welding device 10 and are designed as suction chambers.

[0053] The switching device 109 for switching between the operating mode and the cooling mode can be operated via the communication unit 36. In the operating mode, the welding material is welded in the welding device 10. In the cooling mode, in which welding of the welding material does not occur, in particular, the preheating zone 20 and the welding zone 22 are cooled. Here, the switching device 109 can operate or include an actuator and an adjustment mechanism.

[0054] In operating mode, heated chamber air 114 surrounded by the hood 25 is sucked from the chamber 30 via the suction element 104. On the other hand, process gas 113 is sucked in the region of the inlet 12 and outlet 14 via the suction element 108, thereby preventing an undesired escape of process gas 113 from the inlet 12 or outlet 14.

[0055] On the other hand, in cooling mode, such as from Figure 7 As can be seen in FIG. 1 , the process gas 115 is only sucked from the process channel 16 via the suction element 106. In the cooling mode, no air is sucked from the hood chamber 30 via the suction element 104.

[0056] Figure 6 Schematically indicated are two suction devices 110, for example in the form of fans or vacuum pumps, which can be connected to suction nozzles 111 of the welding device 110. Instead of two suction devices 110, it is also conceivable to provide only one suction device 110, which then sucks air or process gas from the two suction nozzles 111. In each case, a cooling and cleaning unit 112 is connected downstream of the respective suction device 110, in which the sucked process gas is cooled and cleaned.

[0057] The air 117 that has passed through the suction device 110 and the cleaning unit 112 may be discharged into the environment. The suction device 110 or the cleaning unit 112 may be arranged outside the welding apparatus 10.

[0058] In order to enable ambient air to subsequently flow into the welding device 110 in the cooling mode, Figure 6 The indicated closable suction elements 116 are arranged on the underside of the welding device 100. One of these suction elements 116 is Fig. 9 Thus, in the cooling mode, when the process gas 115 is sucked from the process channel 16 via the suction device 110, the suction element 116 will be activated and opened.

[0059] In accordance with Figure 7 In the cross section of , it can be seen that the suction channel 100 has a rectangular cross section. In addition, a first type of suction element 104 and a second type of suction element 106 are shown. The suction element 104 is arranged so that in the closed position of the cover 25, they extend approximately horizontally and transversely to the conveying direction 18. The suction element 104 provides a plurality of suction ports 118 distributed in its longitudinal range. Finally, the hood air 114 in the area directly below the cover 25 or in the area of ​​the motor 51 is sucked via the suction ports 118.

[0060] The second type of suction elements 106 are designed as curved tubes or hoses and each have a suction opening 118 which, when the cover 25 is closed, is located in the region of the process channel 16 and in cooling mode sucks process gas 115 from the process channel 16. The suction element 106 has an end 120 which extends vertically so that the suction opening 118 adjoins or extends into the process channel.

[0061] As from Figure 7 As can be seen in FIG. 1 , the suction elements 104 and 106 each have a nozzle 122 leading to the central suction channel 100. The nozzles 122 of the two suction elements 104 and 106 are located in each case on adjacent channel walls 124, 126. Figure 7 As is also clear from the drawing, the pipe openings 122 of the various suction pipes 104 and 106 are in each case located in a cross section extending perpendicularly to the longitudinal axis of the suction channel 100 .

[0062] Furthermore, a closing element 128 in the form of a pivot flap 130 is provided in the suction channel 100. The pivot flap 130 can be pivoted between different positions about a pivot axis 132 extending parallel to the axis of the suction channel 100 or parallel to the conveying direction 18. Figure 7 In the first pivoted position shown, the pivot flap 130 closes the nozzle 122 of the suction element 106 and the nozzle 122 of the suction element 104 is open. Thus, the hood air 114 can be sucked.

[0063] In the second position, in cooling mode, the pivot flap 130 is pivoted in the direction of the arrow 136 until it closes the nozzle 122 of the suction pipe 104. In this position, the process gas 115 can be sucked from the process channel 16 only by the suction element 106 passing therethrough.

[0064] As from Figure 6As is clear from the figure, a total of six first suction elements 104 and four second suction elements 106 are provided. Six closing elements 128 are then preferably provided in the suction channel 100, with which the individual nozzles 122 are closed. It is also advantageous if the closing elements 128 or the pivoting flaps 130 are jointly controlled via the switching device 109. It is conceivable that a control shaft 133 operable by the switching device 109 is provided, on which the individual pivoting flaps 130 are arranged in a rotationally fixed manner.

[0065] A cross-section is shown transversely to the conveying direction 18 and through the third suction element 108 at the outlet 14. Figure 8 It is clearly shown that the suction element 108 is sucked through by the hood air 114 or the process gas 115 and has an inflow 150 that can be closed by the closing element 128. The closing element 128 is coupled to the drive shaft 133 via a mechanism 152 so that in the operating mode, the inflow 150 is open and in the cooling mode, the inflow 150 is closed. Here, the closing element 128 can be displaced along the arrow 154 toward the inflow 150. Therefore, the suction elements 104 and 108 can be closed or opened simultaneously via the switching device 109 or the control shaft 133 connected thereto.

[0066] like Fig. 9 As shown, the suction elements 116 are preferably mounted in the lower region of the welding device 10 near the bottom. Each suction element 116 provides a flap 136, which can be adjusted between an open position and a closed position via an adjustment element 138. A suction pipe 142, which preferably leads to the process channel 16, is connected to the flap 136.

[0067] In the figure the suction element 116 is shown in the operating mode. Fig. 9 In the cooling mode, the flap 136 and thus the suction pipe 142 are closed. In the operating mode, no fresh air is sucked in through the suction element 116 in order to obtain a predetermined temperature distribution in the welding device. Instead, it is the case that in the operating mode, a gas, in particular nitrogen, is introduced into the welding device 10 in particular in order to prevent oxidation at the weld joint during the welding process. In the cooling mode, the respective suction element 116 is in an open position in which the respective flap 136 is open so that fresh air for cooling can flow into the process channel 16 via the free end 140 of the respective suction pipe 142.

[0068] When switching to the cooling mode, the adjusting element 138 is thus controlled such that the flap 136 is opened. When switching to the operating mode, the adjusting element 138 is controlled such that the flap 136 is closed.

[0069] With the described welding device 10, in particular when contour changes are imminent, process gas 115 can be extracted from the process channel 16 or the preheating zone 20 and / or the process zone 22 via the central extraction channel 100. Thus, fast and reliable cooling, in particular of the preheating zone 20 and the process zone 22, can be achieved.

Claims

1. A welding device (10) for continuously welding printed circuit boards along a conveying direction (18), The soldering device (10) has an inlet (12) and an outlet (14) for supplying and removing the printed circuit board. The welding device (10) has a process channel (16) including a preheating zone (20), a welding zone (22) and / or a cooling zone (24). The welding device (10) has a body (60) and at least one cover (25) which can be displaced between a closed position and an open position. in, The cover (25) surrounds a cover chamber (30), the cover chamber (30) is located above the process channel (16), and a fan motor (51) is arranged in the cover chamber (30). It is characterized in that A central suction channel (100) is arranged in the cover chamber (30), the central suction channel (100) extending approximately parallel to the conveying direction (18) and being configured to reinforce the cover (25). The welding device (10) is provided with a first suction element (104) connected to the central suction channel (100) in the hood chamber (30), the first suction element (104) being used to suck hood chamber air (114) from the hood chamber (30), The welding device (10) is provided with a second suction element (106) connected to the central suction channel (100) in the hood chamber (30), the second suction element (106) being used to suck process gas from the process channel (16), and The welding device (10) is provided with a switching device (109), which is configured to switch between an operating mode and a cooling mode, wherein the operating mode is used to suck the hood air (114) via the first suction element (104); and the cooling mode is used to suck the process gas via the second suction element (106).

2. The welding device (10) according to claim 1, It is characterized in that A third suction element (108) is provided at the inlet (12) and / or the outlet (14), and the switching device (109) is arranged and constructed so that in the operating mode, the process gas is sucked from the area of ​​the inlet (12) and / or the outlet (14) via the third suction element (108), and so that in the cooling mode, no process gas is sucked via the third suction element (108).

3. The welding device (10) according to claim 1, It is characterized in that The first suction element (104) is designed as a suction pipe having a suction opening (118), which is arranged in the region of the underside of the cover (25) and the fan motor (51).

4. The welding device (10) according to claim 1, It is characterized in that In the closed position of the cover (25), the first suction element (104) has a portion which extends approximately horizontally and / or transversely to the conveying direction (18) and has a plurality of suction openings (118) over its longitudinal extent.

5. The welding device (10) according to claim 1, It is characterized in that The second suction element (106) is designed as a suction tube having a suction opening (118), wherein in the closed position of the cover (25), the suction opening (118) is located in the region of the process channel (16).

6. The welding device (10) according to claim 1, It is characterized in that In the closed position of the cover (25), the second suction element (106) has a substantially vertically extending end (120), the end (120) having an open free end, the end being arranged in the process channel (16) or adjacent to the process channel (16).

7. The welding device (10) according to claim 1, It is characterized in that The nozzle (122) of the first suction element (104) and the nozzle (122) of the second suction element (106) in each case open adjacently into the central suction channel (100), and the switching device (109) comprises closing elements (128) and / or operates the closing elements (128) so that in the operating mode, these closing elements close the nozzle (122) of the second suction element (106) and in the cooling mode, close the nozzle (122) of the first suction element (104).

8. The welding device (10) according to claim 7, It is characterized in that The closing element (128) is designed in each case as a pivot flap (130) which is adjustable about an adjustment axis (132).

9. The welding device (10) according to claim 7, It is characterized in that The switching device (109) comprises or operates a controllable actuator and / or adjusting mechanism, via which a plurality of closing elements (128) can be adjusted together.

10. The welding device (10) according to claim 1, It is characterized in that A suction element (116) is provided, which can be switched between an open position and a closed position and can be controlled so that in the operating mode, the suction element (116) is closed, and in the cooling mode, the suction element (116) is opened.

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