DE102014212837B4 - Joining device and method for joining workpieces subject to tolerances - Google Patents

Abstract

Joining device (1) for joining a first workpiece (21), which is subject to tolerances and is at the top in a radiation direction (9) of a radiant energy input, to a second workpiece (22), which is subject to tolerances and is below in the radiation direction (9), by means of the energy input, in particular by means of laser transmission Welding, the joining device (1) comprising a clamping device (12) which clamps a carrier surface (4), and a clamping element (123) for applying a prestressing force to the workpieces (21, 22) in a force direction (43) on the workpieces (21 , 22); ) runs at an adjustment angle (40') to the support surface (4), the clamping device (12) comprises a first clamping frame (121) which can be pivoted reversibly about a first pivot axis (41) in the first direction (410), and a second clamping frame (122) which can be pivoted reversibly about a second pivot axis (42) in the second direction (420), characterized in that the joining device (1) has a first sensor (51) for detecting the first pivot angle (411) of the first clamping frame (121) about the first pivot axis (41) and a second sensor (52) for detecting a second pivot angle (421) of the second clamping frame (122) about the second pivot axis (42).

Description

State of the art

The present invention relates to a joining device for joining a first workpiece subject to tolerances, which is at the top in a radiation direction of a radial energy input, to a second workpiece subject to tolerances, which is lower in the radiation direction, by means of the energy input, in particular by means of laser transmission welding, the joining device having a clamping device for introducing a Includes biasing force in a direction of force on the workpieces. The present invention further relates to a method for joining the workpieces subject to tolerances to one another.

Workpieces, for example made of plastic, are often firmly bonded to one another by means of laser welding. In the case of transmission welding, the material of the upper workpiece facing the laser beam is transparent or partially transparent for the laser beam used, so that the laser beam penetrates this workpiece with little or no effect on the material. The workpiece arranged underneath, on the other hand, is not transparent to the laser beam and is heated by the laser beam so that it melts. By heating the lower work piece, the upper work piece is also heated and melted, allowing the materials of the work pieces to bond together. After cooling and hardening, they are firmly bonded to one another.

In the case of workpieces subject to tolerances, it is necessary for the joining surfaces of the workpieces to touch so that the lower workpiece in the direction of radiation can heat up the upper workpiece and thereby melt it, so that there are no gaps in the weld seam between the workpieces and the weld seam is even.

In order to avoid such gaps, the reference discloses EP 1 060 837 B1 a transmission laser welding device, in which the workpieces are clamped and pressed together at their joining surfaces. With this welding device, the workpieces are clamped between two clamping jaws arranged parallel to one another.

However, the clamping pressure that acts on the workpieces when using such parallel tools is different in some areas due to tolerances of the workpieces over the welding contour. As a result, the welding result, i. H. the resulting weld seam, uneven.

The DE 10 2009 053 863 A1 shows a positioning device for a manual welding device with a pressure plate and a positioning ring.

The DE 20 2008 006 180 U1 shows a laser device for joining plastic workpieces using pressure blasting technology with a focusing device for the laser beam.

The EP 1 306 196 A1 shows a holding device for pressing two workpieces against one another, the workpieces being intended to be pressed against one another for welding with laser light.

Disclosure of Invention

The object of the invention is to create a method for assembling such tolerance-prone workpieces and a clamping device for it, with which the weld seam achieved is improved, in particular more uniform, and/or with which the clamping pressure on the workpieces, in particular during welding, is welding path is constant.

The object is achieved with a joining device having the features of patent claim 1 and a method having the features of patent claim 11. Advantageous embodiments are described in the independent claims.

A joining device is created for this purpose, which is provided for joining a first workpiece subject to tolerances, which is at the top in a radiation direction of a radiant energy input, and is subject to tolerances, to a second workpiece, which is subject to tolerances, and is below in the radiation direction, by means of the energy input. The joining device comprises a clamping device which clamps a carrier surface and which has a clamping element which is provided for applying a prestressing force in a direction of force to the workpieces.

The tensioning element can be adjusted from a basic position, in which the direction of force runs at a basic angle to the support surface, into an adjustment position, in which the direction of force runs at an adjustment angle to the support surface.

As a result, the direction of force in which the preload force is applied to the workpieces can be adjusted depending on the tolerances of the workpieces. As a result, the workpieces can be joined together more precisely, in particular without gaps between them.

In order to adjust the tensioning element from the basic position to the adjustment position, the tensioning device comprises a first tensioning frame which can be rotated about a first pivot axis into a is pivotable in the first direction, and a second clamping frame which is reversibly pivotable about a second pivot axis in a second direction. The first pivot axis and the second pivot axis are preferably arranged transversely to one another.

The joining device is characterized by a first sensor for detecting the first pivot angle and a second sensor for detecting a second pivot angle. As a result, pivoting of the clamping element, in particular during welding, can be detected. The pivoting of the clamping element can then be controlled in a targeted manner by varying the prestressing force.

A laser beam is preferred as the radiant input of energy. The joining device is particularly preferably used for laser transmission welding and is a laser transmission welding device. However, it is also suitable for other energy inputs, for example for ultrasound for joining by means of ultrasonic welding. In the following, the introduction of the energy input is referred to as welding.

For this it is preferred that the first pivot axis and/or the second pivot axis span the support surface. The pivot axes and the carrier surface particularly preferably run transversely to the direction of radiation. However, depending on the installation space conditions and/or the shape of the workpieces, a different arrangement of the pivot axes and the carrier surface with respect to the radiation direction and/or the pivot axes with respect to one another is also preferred. In addition, it is also preferred to change the radiation direction as a function of the installation space conditions and/or the shape of the workpieces.

The clamping device preferably has a stationary frame holder in which the first clamping frame and the second clamping frame are mounted. The second clamping frame is preferably arranged in the first clamping frame such that it can be pivoted about the second pivot axis. Furthermore, the first clamping frame is preferably mounted in the stationary frame holder such that it can be pivoted about the first pivot axis. The clamping element is preferably arranged in the second clamping frame.

The energy input is preferably introduced through a passage provided in the tensioning element. The tensioning element is preferably made of a material that is resistant to the energy input, for example stainless steel.

The passage preferably has a cross-sectional contour that corresponds to the welding path. Furthermore, the clamping element preferably has a support edge with which it bears against an upper side of the first workpiece in the direction of radiation. The support edge particularly preferably rests on an edge of the first workpiece. Depending on the shape of the workpieces and/or the welding path, however, other arrangements are also conceivable.

In order to position the workpieces in the joining device, it is preferred that the joining device comprises a workpiece holder. The workpiece holder enables the workpieces to be arranged on one another, so that the first workpiece is at least partially in contact with the second workpiece. The workpieces are preferably arranged one above the other in the vertical direction. For this purpose, the workpiece holder preferably has a workpiece holder, which is provided for receiving the second workpiece. If the two workpieces are arranged vertically, the first workpiece can then be placed on the second workpiece. However, the invention also includes a joining device in which workpieces arranged next to one another or workpieces arranged at a different angle to one another are welded to one another.

In addition, it is preferred that the workpiece holder has fixing means for fixing the second workpiece. The second workpiece is preferably fixed in the basic position of the clamping element. It is particularly preferably fixed with the fixing means against displacement in and against a horizontal direction. As a result, the clamping element can then be moved into the adjustment position without changing the positioning of the second workpiece in and against the horizontal direction.

In a preferred embodiment, the workpiece holder is displaceable or adjustable. Or also preferred is the carrier or the workpiece holder, and with it the workpiece holder, displaceable or adjustable. As a result, the workpiece holder can be brought closer to the clamping element. In a further preferred embodiment, the clamping element or the clamping device, and with it the clamping element, can be displaced or adjusted. As a result, the clamping element can be brought closer to the workpiece holder, in particular it can be moved closer. The workpiece holder and/or the clamping element are preferably height-adjustable in the vertical direction. This embodiment is intended for welding work pieces arranged one on top of the other to one another.

The fixing means are preferably designed as grippers. Preferably, at least one gripper is adjustable in a gripping direction, so that the Grei fer are approachable to each other. Both grippers are particularly preferably adjustable in opposite directions to one another. As a result, the second workpiece can be gripped between the grippers.

In a preferred embodiment, the fixing means are arranged on a carrier component of the workpiece holder. They are particularly preferably arranged in a stationary manner on the carrier component. However, an embodiment is also preferred in which the fixing means can be moved or adjusted together, in particular the height can be adjusted. As a result, the joining device can be adapted to workpieces with different dimensions.

The workpiece holder is preferably adjustable in height. As a result, it can be moved up to the clamping element until the clamping element is in contact with the upper side of the first workpiece. However, an embodiment is also preferred in which the clamping element or the clamping device can be moved up to the workpiece holder.

To adjust the tensioning element from the basic position to the adjustment position, it is preferable for the tensioning element to be subjected to a holding force. The holding force presses the first workpiece onto the second workpiece. Furthermore, the clamping element is preferably subjected to the prestressing force during welding, which presses the first workpiece onto the second workpiece. The prestressing force is preferably greater than the holding force, since this is used to displace a melt produced when the second workpiece is melted.

Furthermore, the tensioning device preferably comprises a locking means for locking the tensioning element in the adjustment position. The locking means is preferably a hydraulic locking means. However, a pneumatically acting locking means can also be used. In this embodiment, the fixing means not only allows the clamping element to be fixed in its adjustment position, but also an adjustable fixing, in which the adjustment of the clamping element is still possible in a damped manner, in particular when a force is applied.

The clamping element particularly preferably comprises a first fixing means for fixing the first clamping frame and/or a second fixing means for fixing the second clamping frame. In this embodiment, the clamping frames can be fixed separately from one another in an application-specific manner.

It is also preferred that the joining device includes a hold-down device with a support element that is arranged in the passage and presses the first workpiece against the second workpiece during welding. The support element preferably has a cross-sectional contour which is designed to correspond to that of the passage. In order to enable energy to be introduced into the workpieces, it is also preferable for the support element to be smaller than the opening, so that a gap remains between the supporting element and the opening for the energy input.

• a) Anordnen der Werkstücke aneinander, so dass das erste Werkstück zumindest teilweise am zweiten Werkstück anliegt,
• b) Anordnen des Spannelementes am ersten Werkstück,
• c) Fixieren des zweiten Werkstücks,
• d) Beaufschlagen des Spannelementes mit einer Haltekraft, wobei sich das Spannelement von einer Grundposition in eine Verstellposition verstellt,
• e1) entweder Fixieren des Spannelementes,
• e2) oder verstellbares Feststellen des Spannelementes,
• f) Beaufschlagen des Spannelementes mit einer Vorspannkraft,
• g) Einbringen eines strahlenförmigen Energieeintrags in eine Strahlungsrichtung in die Werkstücke, und
• f) Aushärten der Werkstücke.

The object is also achieved with a method for the integral joining of a first workpiece subject to tolerances to a second workpiece subject to tolerances by means of a radial energy input, in particular by means of laser transmission welding, with such a joining device, with the steps:

• a) arranging the workpieces on one another, so that the first workpiece rests at least partially on the second workpiece,
• b) arranging the clamping element on the first workpiece,
• c) fixing the second workpiece,
• d) subjecting the clamping element to a holding force, with the clamping element moving from a basic position to an adjustment position,
• e1) either fixing the clamping element,
• e2) or adjustable locking of the clamping element,
• f) subjecting the tensioning element to a pretensioning force,
• g) introducing a radiant energy input in a radiation direction into the workpieces, and
• f) hardening of the workpieces.

By adjusting the clamping element from the basic position to the adjustment position, the first workpiece is already pressed against the second workpiece with the holding force before welding in such a way that there are fewer or no gaps between the workpieces. As a result, waviness of the joining surfaces of the workpieces, which leads to gaps, can be compensated for very well. Then the clamping element, and via the clamping element the first workpiece, is subjected to a prestressing force and welded. The process enables the workpieces to be bonded together over the entire welding path.

When the tensioning element is fixed in an adjustable manner, the tensioning element can be adjusted in a damped manner, at least when a force is applied, in particular the pretensioning force. By melting a melting edge, the first workpiece with the Clamping element shifted in the direction of the force by the distance by which the melting edge deforms/reduces. As a result, a more even weld seam can be achieved.

If the volume of the melting edge varies due to tolerances in the workpiece, the path by which the first workpiece is displaced varies, possibly in certain areas. In order to avoid stresses in the first workpiece, it is also preferred that the adjustment of the clamping element is detected during the introduction of the energy input and the applied prestressing force is changed. The pretensioning force is preferably reduced when the tensioning element is displaced significantly. The pretensioning force is also preferably increased when there is little or no displacement. As a result, differences in the volume of the melting edge, in particular differences in its width, can be compensated for.

In order to change the pretensioning force and/or the adjustment of the tensioning element in a targeted manner, it is also preferred that the adjustment angle is recorded, in particular by recording the first and second pivot angle, before the fixing or adjustable locking of the tensioning element, or is recorded continuously. With this method, a very even fusion seam can be achieved.

In order to compensate for differences in the width of the melting edge, it is also preferable for the power of the radiant energy input to be regulated in certain areas, in particular by regulating the speed at which the radiant energy input travels the welding path.

The energy input is introduced into the workpieces along a welding path. The welding path is preferably traversed several times, preferably about 8-15 times.

• 1 in (a) - (d) verschiedene Ansichten einer Spannvorrichtung für die Fügevorrichtung, und in (e) und (f) jeweils einen Ausschnitt aus der Fügevorrichtung in verschiedenen Ansichten,
• 2 in (a) eine erste Ausführungsform eines Niederhalters für die Fügevorrichtung aus 1, und in (b) und (c) verschiedene Ansichten einer weiteren Ausführungsform eines Niederhalters für die Fügevorrichtung aus 1, und
• 3 in (a) ein erstes toleranzbehaftetes Werkstück und einen Ausschnitt aus einem zweiten toleranzbehafteten Werkstück, und in (b) die beiden aneinander angefügten toleranzbehafteten Werkstücke aus (a).

The invention is described below with reference to figures. The figures are merely exemplary and do not limit the general inventive concept. Show it

• 1 in (a) - (d) different views of a clamping device for the joining device, and in (e) and (f) a section of the joining device in different views,
• 2 in (a) shows a first embodiment of a hold-down device for the joining device 1 , and in (b) and (c) different views of a further embodiment of a hold-down device for the joining device 1 , and
• 3 in (a) a first workpiece subject to tolerances and a section from a second workpiece subject to tolerances, and in (b) the two workpieces subject to tolerances joined together from (a).

1 shows in (a) a perspective view of a clamping device 12 for a joining device 1 according to the invention, the 1 (b) and (c) sectional views, respectively, and the 1 (d) a plan view of the clamping device 12 from 1 (a) .

The joining device 1 is provided for joining a first workpiece 21, which is subject to tolerances and is at the top in a radiation direction 9 of a radiant input of energy, to a second workpiece 22, which is subject to tolerances and is below in the radiation direction 9, by means of the energy input (see Fig. 3 ). For this purpose, it includes a clamping device 12 and a workpiece holder 13. It also includes a radiation source for generating the radiant energy input (not shown).

The radiation source is preferably a laser, with the radiant input of energy being a laser beam. This is preferably used for laser transmission welding. However, the joining device 1 is also suitable for other energy inputs, for example for ultrasound for joining by means of ultrasonic welding. In the following, the introduction of the energy input is referred to as welding.

The clamping device 12 has a clamping element 123 which is provided for applying a prestressing force to the two workpieces 21, 22. The prestressing force acts in a force direction 43 (see 1 (b) and (c)) on the workpieces 21, 22. The direction of force 43 can be adjusted with the clamping element 12. It is aligned in a normal direction transverse to a notional plane (not shown) spanned by the clamping element 123 .

To set the direction of force 43, the clamping element 123 is moved from a basic position G, in which the direction of force 43 runs at a basic angle 40 to a support surface 4, which clamps the clamping device, into an adjustment position V, in which the direction of force 43 runs at an adjustment angle 40'. runs to the support surface 4, adjustable.

Since the direction of force 43, in which the prestressing force is applied to the workpieces 21, 22, can be adjusted, tolerances in the workpieces 21, 22 that lead to gaps between the workpieces 21, 22 can be compensated for with the clamping device 12, so that during there are no gaps between the workpieces 21, 22 during welding.

For this purpose, the clamping device 12 has a frame holder 120 which is spaced apart from a mounting plane 150 by spacers 124 . The Frame holder 120 is provided in a stationary manner in the joining device 1 .

A first clamping frame 121 is mounted in the frame holder 120 so that it can be pivoted reversibly about a first pivot axis 41 in a first direction 410 . In addition, a second clamping frame 122 is mounted reversibly in the first clamping frame 121 so that it can pivot in a second direction 420 about a second pivot axis 42 . The first pivot axis 41 and the second pivot axis 42 span the support surface 4 . They are arranged horizontally here. The clamping element 123 is arranged in the second swing frame 122 .

In this arrangement, the clamping element 123 can be pivoted with the first pivot frame 121 about the first pivot axis 41 in and against the first direction 410, and with the second pivot frame 122 about the second pivot axis 42 in and against the second direction 420. By pivoting the tensioning element 123 about the first and/or the second pivot axis 41, 42, the direction of force 43 is adjusted from the basic angle 40 to the adjustment angle 40'. The first clamping frame can preferably be pivoted by a first pivoting angle of about 2-5°, particularly preferably by about 3-4°, very particularly preferably by about 3.4°. The second clamping frame can preferably be pivoted by a second pivoting angle of about 3-6°, particularly preferably by about 4-5°, very particularly preferably by about 4.5°.

The clamping element 123 has a support edge 127 with which it bears against an upper side of the first workpiece 21 in the radiation direction 9 during welding. The support edge 127 is flat. In the basic position G it is preferably arranged horizontally. The basic angle 40 is then 90° in the basic position G. In the embodiment shown here, the direction of force 43 in the basic position G is therefore arranged transversely to the carrier surface 4 and the imaginary plane spanned by the tensioning element 123 is therefore arranged parallel to the carrier surface 4 .

The shape of the support edge 127 is designed here to correspond to the cross section of the first workpiece 21 . During welding, it lies at a first edge 210 (see Fig. 3 ) of the first workpiece 21. Depending on the course of the welding path, however, a different contour of the bearing edge 127 is also possible.

1 (b) shows a section through the clamping device 12 along the second pivot axis 42 in the basic position G.

When the clamping element 123 is pivoted about the first pivot axis 41 in the first direction 410, the force direction 43 is pivoted from the base angle 40 by the first pivot angle 411 in the first direction 410 into the adjustment angle 40'. The direction of force 43' pivoted about the adjustment angle 40' is marked with a prime. In the region of the clamping element 123, the second pivot axis 42 then runs along an imaginary second pivot axis 42' pivoted by the first pivot angle 411. This is with dashed lines in the 1 (b) shown.

Here, the support edge 127 is pivoted parallel to the imaginary second pivot axis 42'.

1(c) shows a section through the clamping device 12 along the first pivot axis 42 in the basic position G.

When the clamping element 123 is pivoted about the second pivot axis 42 in the second direction 420, the force direction 43 is pivoted from the base angle 40 by the second pivot angle 421 in the second direction 420 into the adjustment angle 40'. The direction of force 43' pivoted about the adjustment angle 40' is marked with a prime. In the region of the clamping element 123, the first pivot axis 41 then runs along an imaginary first pivot axis 41' pivoted by the second pivot angle 421. This is with dashed lines in the 1(c) shown.

The support edge 127 is pivoted parallel to the imaginary first pivot axis 41'.

The 1 (b) and (c) only show the pivoting of the tensioning element 123 about one of the two pivot axes 41, 42. However, the tensioning element 123 can also be pivoted about both pivot axes 41, 42 at the same time.

A passage 125 for the introduction of energy is provided in the tensioning element 123 . The passage 125 has a cross-sectional contour corresponding to the welding path. However, a clamping element 123 can also be used, the passage 125 of which has a different contour. However, the passage 125 must be larger than the welding path, and the bearing edge 127 must be able to be placed against the first workpiece 21 .

In order to fix the clamping frames 121, 122 in the adjustment position V, the clamping device 12 has a first fixing means 61 for fixing the first clamping frame 121 and/or a second fixing means 62 for fixing the second clamping frame 122. The clamping frames 121, 122 can be fixed with the locking means 61, 62 in such a way that they no longer move even when the prestressing force is applied. For this are preferred hydraulically and/or pneumatically acting locking means 61, 62 are used.

However, the locking means 61, 62 also allow an adjustable locking, in which the adjustment of the tensioning element 123 is still possible in a damped manner, in particular when a force is applied.

In order to detect the adjustment of the clamping element 123, in particular during welding, and/or to specifically change the applied preload force when the clamping element 123 is fixed or not fixed, the clamping device 12 also has a first sensor 51 for detecting the first swivel angle 411. and a second sensor 52 for detecting a second pivoting angle 421. The pivoting of the clamping element 123 can be controlled in a targeted manner by varying the prestressing force applied, in particular during welding.

In order to weld the workpieces 21, 22 to one another, they are first arranged in the joining device 1. The joining device 1 has a workpiece holder 13 for this purpose. The workpiece holder 13 is in the 1 (e) and (f) shown. The 1 (e) shows the joining device 1 in a perspective view obliquely from below. As a result, the clamping element 123 can be seen from below. The 1 (f) shows the joining device 1 in a perspective view obliquely from above.

The workpiece holder 13 is arranged above the assembly level 150 . It comprises a carrier plate 130 which can be pulled out of the joining device 1 in a reversible manner in a pulling direction 91 and on which a workpiece holder 131 is arranged. For this purpose, a handle 132 is provided on the support plate 130 as a handle for the operator.

The workpiece holder 131 is pot-shaped, so that the second workpiece 22 can be placed in an interior (not labeled) of the workpiece holder 131 . The first workpiece 21 can be placed against the second workpiece 22 .

In order to fix the second workpiece 22 during welding, the workpiece holder 13 has fixing means 111, 112. The fixing means 111, 112 are designed as grippers. They are each provided for fixing the second workpiece 22 in a horizontal direction. As a result, the second workpiece 22 is no longer horizontally adjusted when the clamping element 123 and/or the first workpiece 21 is pivoted, in particular when the first workpiece 21, 22 is welded to the second. For this purpose, the grippers 111, 112 are designed to be reversibly approachable to one another, for example displaceable or pivotable in opposite directions, so that the second workpiece 22 can be gripped between the grippers 111, 112.

The grippers 111, 112 are arranged here on a stationary support component 151 of the workpiece holder 13. In order to be able to adapt the joining device 1 to workpieces 21, 22 of different dimensions, it is also preferred that the grippers 111, 112 on the workpiece holder 13 are displaceable or adjustable, in particular adjustable in height.

In the case of the workpiece holder 13 shown here, the workpiece holder 131 can be reversibly adjusted in height against the radiation direction 9 in a lifting direction 93 . For this purpose, the workpiece holder comprises a lifting mechanism (not shown) that is driven in particular electrically, servo-electrically, pneumatically or hydraulically. In order to place the workpieces 21 , 22 against the clamping element 123 , the workpiece holder 131 is raised in the lifting direction 93 until the upper side of the first workpiece 21 in the radiation direction 9 rests against the clamping element 123 .

In the joining device 1 shown, the radiation direction 9 is the vertical direction from above. Depending on the workpieces 21, 22, introducing the energy input at an angle (not shown) greater than 0° to the vertical direction is also conceivable.

The 2 (a) shows a hold-down device 14 for the joining device 1 of FIG 1 in a top view, the 2 B) to the clamping device 12 of 1 (a) arranged hold-down device 14 of 2 (a) , and the 2(c) a further embodiment of a hold-down device 14. The hold-down device 14 can optionally be arranged on the clamping device 12.

The hold-down device 14 has a support element 142 which is provided for pressing the first workpiece 21 against the second workpiece 22 during welding. This has proven to be advantageous in order to counteract a deformation of the first workpiece 21 during welding. In comparison to a clamping surface formed only by the bearing edge 127, this is enlarged by the bearing element 142. For this purpose, the support element 142 is arranged in the passage 125 so that a gap 146 remains between the support element 142 and the tensioning element 123 for the energy input.

The hold-down device 14 includes a hold-down frame 140 which is arranged above the frame holder 120 . The hold-down frame 140 is fixed in place in the joining device 1 by means of fastening supports 144 . The support member 142 is arranged on a hold-down carrier 141 that can be displaced in a printing direction 94 .

In order to press the first workpiece 21 onto the second workpiece 22 during welding with the hold-down device 14 , force means 63 are arranged on both sides of the hold-down device carrier 141 . A force can be applied to the hold-down support 141 in the pressure direction 94 by means of the force means 63 . As a result, it is displaced in the pressure direction 94. The support element is fastened to the hold-down support 141 so that it is displaced with it in the pressure direction 94 and presses the first workpiece 21 against the second workpiece 22 with the force. The direction of pressure 94 here is the vertical downward direction.

The support element 142 is arranged on a spacer 145 so that it is spaced apart from the hold-down support 141 . So that it rests against the first workpiece 21, it is mounted on a ball joint (not shown). The shape of the support element 142 shown here corresponds to the cross section of the passage 125 and the first workpiece 21. Due to the flexible/pivotable mounting by means of the ball joint, however, another shape is also conceivable.

In order to achieve a continuous weld seam and, if possible, not to impede the radial energy input through the hold-down carrier 141, the hold-down carrier 141 of 2 (a) and (b) a recess 147 on each side of the support element 142 above the gap 146 . The recesses 147 are so large that the hold-down support 141 is only formed by two thin connecting webs 143 in the region of the recesses 147 . The two connecting webs 143 ensure sufficient stability of the hold-down support 141 . In addition, the radial energy input is only slightly covered by them.

The embodiment of 2(c) shows a hold-down device 14 with a hold-down device support 141, which tapers to form a thin connecting web 143 above the gap 146 in each case. In this embodiment, the radiant input of energy is therefore even less covered.

The 3 shows in (a) an embodiment of a first workpiece 21 and a second workpiece 22 in an exploded view. The first workpiece 21 is a cover here, the second workpiece 22 is an upper part of a water pump 2. The water pump 2 with the cover 21 welded to the upper part 22 shows the 3 (b) .

The first workpiece 21 has a bearing edge 210 with which it rests at least partially against a melting edge 220 of the second workpiece 22 before welding. In order to be able to position it easily on the second workpiece 22, an inner edge 211 is provided, which extends transversely to the supporting edge 210.

The melting edge 220 on the second workpiece 22 is intended to be melted off during welding. It is heated by the radial energy input during welding until it melts. Due to the prestressing force acting on the workpieces 21, 22 during welding, the melting edge 220 is displaced from the first workpiece 21 as it melts. The first workpiece 21 is displaced in the direction of pressure 94 until the bearing edge 210 is in contact with a bearing edge 221 of the second workpiece 22 .

The workpieces 21, 22 have manufacturing tolerances, so that a height 212 of the supporting edge 210, a height 223 of the melting edge 220 and a height 222 of the contact edge 221, and a width (not shown) of the melting edge 220 can differ.

The second workpiece 22 is arranged in the workpiece holder 131 in order to achieve a continuous, cohesive and uniform weld seam (not shown). For this purpose, the carrier plate 130 is pulled out of the joining device 1 in the pulling direction 91 and the second workpiece 22 is then placed. The first workpiece 21 is then arranged on the second workpiece 22 so that its bearing edge 210 rests at least partially on the melting edge 220 . The inner edge 211 then extends into the second workpiece 22 .

The first and second workpieces 21, 22 are arranged in the workpiece holder 131 manually by an operator. However, a joining device 1 is also preferred in which the extraction of the carrier plate 130 and/or the arrangement of the workpieces 21, 22 are automated.

Then the clamping element 123 is arranged in the basic position G on the first workpiece 21 . For this purpose, the carrier plate 130 is raised in the lifting direction 93 until the clamping element 123 is in contact with the first workpiece 21 . The second workpiece 22 is then fixed in its position with the fixing means 111, 112, so that the second workpiece 22 no longer moves horizontally when the clamping element 123 is subjected to a force.

Thereafter, the workpiece holder 13 is raised further until the clamping element 123 is subjected to a holding force. The holding force is preferably about 100-1000N, particularly preferably about 600-800N, very particularly preferably 650N. It presses the second workpiece 22 against the first work piece 21, and the first workpiece 21 to the clamping element 123. The clamping element 123 moves from the basic position G to the adjustment position V.

In the embodiment of the joining device 1 shown here, the lifting mechanism of the workpiece holder 13 is therefore used to introduce the force into the clamping element 123 . However, other embodiments are also preferred in which, for example, the force is introduced into the clamping element 123 by a separate power source (not shown), or in which the clamping device 12 is moved/lowered to the workpiece holder 13 .

In the basic position G, the first pivoting angle 411 is detected by the first sensor 51 and the second pivoting angle 421 is detected by the second sensor 52 (zeroing).

Then, in a first variant of the method, the clamping element 123 is fixed with the locking means 61, 62, so that the clamping frames 121, 122 can no longer pivot. In a second variant of the method, the clamping element 123 is fixed in such a way that the clamping frames 121, 122 can be pivoted at least in a stiff/damped manner when a force is applied, in particular the prestressing force. The fixing of the clamping element 123, in which the clamping frames 121, 122 can be pivoted at least dampened/sluggishly when the force is applied, is referred to here as adjustable fixing.

The clamping element 123 is then subjected to the prestressing force by lifting the workpiece holder 12 . The prestressing force is greater than the holding force, since this is used to displace the melting edge 220. It is preferably about 100-1000N, particularly preferably about 850N.

After that, the radiant input of energy is introduced into the workpieces 21, 22. It penetrates the first workpiece 21, which is the upper one in the direction of radiation 9, with only a slight effect on the material. The second workpiece 22, which is the lower one in the radiation direction 9, is heated with the radiant input of energy. The energy input is introduced in such a way that it hits the melting edge 220 of the second workpiece 22 and heats it. The weld path therefore runs along the melting edge 220.

This is heated so much that it melts. The area of the first workpiece 21 lying against it is also heated and melts.

The first workpiece 21 is pressed against the second workpiece 22 so strongly by the prestressing force that the melting edge 220 is at least partially displaced.

The radiant input of energy is introduced into the second workpiece 22 by following the melting path approximately 8-15 times, preferably 10-12 times. A laser with a power of about 200 watts is preferably used for the radiant energy input. Suitable lasers have an output of about 30-500 watts.

Subsequently, the radiant energy input is stopped, with the prestressing force being maintained for a hold time until the materials of the workpieces 21, 22 have hardened. The retention time is preferably about 1 s. Since the materials of both workpieces 21, 22 melt during the welding, the workpieces 21, 22 are bonded to one another along the weld seam.

In the first variant of the method, the prestressing force is constant during the welding of the workpieces 21, 22. In addition, the clamping frames 121, 122 are fixed in the adjustment position V, so that the first workpiece 21 and the clamping element 123 can no longer be adjusted during welding.

However, due to manufacturing tolerances, such as a changing height 212, 223, 222 of the supporting edge 210, the melting edge 220 or the contact edge 221, or a changing width of the melting edge 220, the resulting weld seam can be unevenly thick, and/or the Melting edge 220 may not have completely melted off/displaced.

The second method variant is used to further compensate for such tolerances. In this variant of the method, the clamping frames 121, 122 can still be pivoted in a damped manner when a force is applied, in particular the prestressing force. As a result, the first workpiece 21 is misaligned/tilted if the melting edge 220 melts unevenly. The clamping element 123 is adjusted with it, so that the clamping frames 121, 122 pivot.

The second variant of the method can be carried out with a constant prestressing force. However, if the melting edge 220 melts to different extents in some areas, there is a risk that stresses will occur in the first workpiece 21 .

Therefore, the pivoting of the clamping frames 121, 122 during the welding is recorded in a third variant of the method. The sensors 51, 52 are used for this. They are designed here as distance sensors. If the clamping element 123 pivots, this is detected as a pivoting of one of the clamping frames 121, 122 or as a pivoting of both. The measured values recorded are used to regulate the applied preload force.

The biasing force applied is changed by the lifting mechanism lowering or raising the workpiece holder 13 . In the event of strong pivoting, for example due to a narrow melting edge 220, the prestressing force is reduced by the workpiece holder 13 being lowered against the lifting direction 93. In the event of slight pivoting, for example due to a wide melting edge 220, the prestressing force is increased by the workpiece holder 13 being raised in the lifting direction 93.

The third variant of the method therefore provides for a deliberate regulation of the prestressing force as a function of the pivoting angles 411, 421 of the clamping frames 121, 122. This reduces or even avoids distortion of the first workpiece 21 during welding. In addition, the weld seam is very even.

The clamping device 12 enables the first workpiece 21 to be adjusted/pivoted, so that it rests better against the second workpiece 22 despite manufacturing tolerances. In a first variant of the method, the workpieces 21, 22 can then be welded with the same prestressing force over the entire welding path.

In order to further reduce or avoid gaps between the workpieces 21, 22 and to achieve an even further improved weld seam, the joining device 1 also allows the clamping element 123 to be adjusted during welding. In this second variant of the method, pivoting of the first workpiece 21 is also possible during the welding.

In order to avoid distortion of the first workpiece 21 during welding, the joining device 1 also makes it possible for the prestressing force to be changed in a targeted manner during the welding with a clamping element 123 that can be adjusted during the welding. In this third variant of the method, differences in the volume of the melting edge 220 provided for melting, in particular differences in the width of the melting edge 220, are compensated for. With a wide melting edge 220, a greater prestressing force can then be used than with a narrow melting edge 220. As a result, a uniform weld seam can be achieved even with a greatly varying melting edge 220.

As an alternative or in addition, the power of the radiant energy input is regulated area by area, for example by the speed at which the radial energy input travels the welding path being locally controlled. This also allows differences in the width of the melting edge 220 to be compensated for and a uniform weld seam to be achieved.

The joining device 1 shown is designed for joining two workpieces 21, 22 arranged one above the other. However, the invention also includes a joining device 1 with workpieces 21, 22 arranged differently to one another, in which these are arranged at an angle greater than 0° to the vertical direction, in particular next to one another. The arrangement of the clamping device 12, the workpiece holder 13 and/or the radiation source are then adapted accordingly.

Claims (12)

Joining device (1) for joining a first workpiece (21), which is subject to tolerances and is at the top in a radiation direction (9) of a radiant energy input, to a second workpiece (22), which is subject to tolerances and is below in the radiation direction (9), by means of the energy input, in particular by means of laser transmission Welding, the joining device (1) comprising a clamping device (12) which clamps a carrier surface (4), and a clamping element (123) for subjecting the workpieces (21, 22) to a prestressing force in a force direction (43) on the workpieces (21, 22), wherein the clamping element (123) from a basic position (G), in which the force direction (43) runs at a basic angle (40) to the support surface (4), into an adjustment position (V), in which the direction of force (43) at an adjustment angle (40') to the support surface (4), the clamping device (12) comprises a first clamping frame (121) which can be rotated about a first pivot axis (41) in the first direction (410) can be pivoted, and a second clamping frame (122) which can be pivoted reversibly about a second pivot axis (42) in the second direction (420), characterized in that the joining device (1) has a first sensor (51) for detecting the first pivot angle (411) of the first clamping frame (121) about the first pivot axis (41) and a second sensor (52) for detecting a second pivoting angle (421) of the second clamping frame (122) about the second pivot axis (42). Joining device (1) according to one of the preceding claims, characterized in that the first pivot axis (41) and/or the second pivot axis (42) span the carrier surface (4). Joining device (1) according to one of the preceding claims, characterized in that the clamping element (123) is arranged in the second clamping seat (122). Joining device (1) according to one of the preceding claims, characterized in that the second clamping frame (122) can be pivoted about the second pivot axis (42) in the first clamping frame (121), and the first clamping frame (121) can be pivoted about the first pivot axis (41). are mounted in a stationary frame holder (120). Joining device (1) according to one of the preceding claims, characterized in that it comprises a first fixing means (61) for fixing the first clamping frame (121) and/or a second fixing means (62) for fixing the second clamping frame (122). Joining device (1) according to one of the preceding claims, characterized in that the clamping element (123) has a bearing edge (127) which bears against an upper side of the first workpiece (21) in the radiation direction (9). Joining device (1) according to one of the preceding claims, characterized in that the clamping element (123) comprises a passage (125) for the introduction of energy. Joining device (1) after claim 7 , characterized in that it comprises a holding-down device (14) with a bearing element (142) which is arranged in the passage (125) and presses the first workpiece (21) against the second workpiece (22) during welding. Joining device (1) according to one of the preceding claims, characterized in that it comprises a workpiece holder (13) for positioning the workpieces (21, 22) in the joining device (1), with a workpiece holder (131) for receiving the second workpiece (22 ), and with fixing means (111, 112) for fixing the second workpiece (22). Joining device (1) after claim 9 , characterized in that the workpiece holder (131) is adjustable in height. Method for the integral joining of a first workpiece (21) subject to tolerances to a second workpiece (22) subject to tolerances by means of a radiant energy input, in particular by means of laser transmission welding, with a joining device according to one of the preceding claims, with the steps: a) arranging the workpieces (21, 22) on one another, so that the first workpiece (21) rests at least partially on the second workpiece (22), b) arranging a clamping element (123) in a basic position (G) on the first workpiece (21), c) fixing the second workpiece (22), d) subjecting the clamping element (123) to a holding force, with the clamping element (123) moving from the basic position (G) to an adjustment position (V), e1) either fixing the clamping element (123), e2) or adjustable fixing of the clamping element (123), f) subjecting the tensioning element (123) to a pretensioning force, g) introducing a radiant energy input in a radiation direction (9) into the workpieces (21, 22), and f) hardening of the workpieces (21, 22). procedure after claim 11 , characterized in that when the tensioning element (123) is fixed in an adjustable manner, an adjustment of the tensioning element (123) during the introduction of the energy input is detected and the applied pretensioning force is changed.

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