Vibration welding equipment and method

Abstract

To provide an apparatus and method capable of reliable welding to a stack of components.SOLUTION: A vibratory welding apparatus for welding a first part 3 to a second part or a stack of parts 5, the vibratory welding head comprises: a first tool 10 which vibrates only along a first axis X in a first plane and serves to receive the first part; a second tool which is a lower tool 12 positioned on a second support, the second tool serves to receive the second part or stack of parts, and the first support and the second support are movable along the second axis Z perpendicular to the first plane from the initial position to the oscillating welding position; and a clamping arrangement with two oppositely arranged clamping devices each having a clamping surface movable along the first axis X between the clamping position and the open position, in the clamping position, movement of the second component or stack of welded components along the first axis X is interfered with during vibratory welding.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] 1. Field of the Invention The present invention relates to a vibration welding apparatus for welding a first component to a second component or a stack of welded components, a vibration welding method using the vibration welding apparatus, a retrofit kit for the vibration welding apparatus, and a respective retrofit method.

Background Art

[0002] 2. Background of the Invention Vibration welding apparatuses for welding two components, usually plastic components, to each other are generally known. Usually, these apparatuses include a frame or housing, in which a lower tool and an upper tool are arranged. The lower tool is fixed to a lifting table, and the upper tool is firmly fixed to an upper tool plate. By means of the lifting table, the lower tool can be moved in the direction of the upper tool, and a first plastic component in the lower tool can be friction-welded or vibration-welded to a second plastic component in the upper tool.

[0003] Such vibration welding apparatuses are used, for example, in the automotive industry and in medical technology. In the automotive industry, vibration welding apparatuses are used in the manufacture of lights, but can also be used in the manufacture of other components or component groups made of or containing plastic. Similarly, vibration welding apparatuses can be used in the manufacture of apparatuses and / or component groups in medical technology or in the manufacture of consumer goods.

[0004] The basic operation of a vibration welding apparatus is as follows. First, the user places a first plastic component on the lower tool. Subsequently, the user places a second plastic component on the first component in the lower tool. Next, the lifting table having the lower tool and the components arranged thereon moves along a vertical axis from an initial position in the direction of the upper tool until the second component is received by the upper tool.

[0005] Next, the first and second parts are welded by friction welding or vibration welding. When the welding is completed, the lifting table moves back to the initial position along the vertical axis from the welding position, together with the lower tool and the composite of the first and second parts arranged thereon. Simultaneously with the lifting table reaching the initial position, the user removes the composite of the first and second parts.

[0006] Each vibration welding device including a preheating arrangement is known, for example, from EP 3 020 532 A1, EP 2 837 492 A1, and EP 3 009 254 A2.

[0007] If one plastic part has to be welded to a stack of already welded plastic parts, i.e., if the plastic part arranged on the lower tool consists of a plurality of already welded plastic parts or layers, the disadvantages of the above-described plastic welding device become apparent. In this case, the vibrations transmitted from the vibration welding head of the upper tool to one plastic part arranged therein are also transmitted to the stack of already welded plastic parts. Depending on the height of the stack of welded plastic parts, the end of the stack of welded parts abutting the first plastic part moves together with one part in the upper tool to such an extent that the resulting weld seam is of reduced quality or no weld connection can be established at all.

[0008] Therefore, an object of the present invention is to provide a welding device that can overcome the above disadvantages and can weld additional parts to a stack of welded parts in a reliable manner. In addition, it is a further object of the present invention to provide a respective vibration welding method. Summary of the Invention

[0009] 3. Summary of the Invention The above problems are solved by the vibration welding apparatus according to independent claim 1, the vibration welding method according to independent claim 7, the retrofit kit according to independent claim 12, and the retrofit method according to independent claim 14. Further preferred embodiments and developments will become apparent from the following description, the drawings, and the appended claims.

[0010] The vibration welding apparatus of the present invention for welding a first part to a second part or a stack of welded parts is a first tool which is an upper tool having a vibration welding head disposed on a first support, wherein the vibration welding head vibrates only in a first plane during use, preferably only along a first axis X, the first tool serving to receive the first part, a second tool which is a lower tool disposed on a second support, the second tool serving to receive the second part or a stack of welded parts, the first support and the second support being movable relative to each other along a second axis perpendicular to at least the first plane from an initial position to a vibration welding position, and a clamping arrangement comprising at least two oppositely disposed clamping devices each having a clamping surface movable along the first axis between a clamping position and an open position, wherein at the clamping position, the movement of the second part or the stack of welded parts along at least the first axis is impeded during vibration welding.

[0011] The vibration welding apparatus of the present invention will be described below based on its use. As a starting point, it is assumed that a first part, preferably a plastic part, is already disposed in a first tool, i.e., an upper tool. For example, it can be held there under pressure. A second part or a stack of welded parts is disposed in a second tool, i.e., a lower tool. The second part or the stack of welded parts is preferably made of a plastic material. For an exemplary operation, the first support of the vibration welding apparatus is an upper mounting plate, and the second support is a lifting table, preferably a lifting table driven by an electric motor or hydraulics. Further, it is assumed that the vibration welding head oscillates only along the first axis in the first plane.

[0012] The second support having the middle and lower tools moves relative to the first support. For example, the second support moves in the direction of the first support which is fixedly arranged. This movement is carried out until the first part abuts against the second part or the stack of welded parts.

[0013] Unlike the prior art, the welding device of the present invention further comprises a clamping arrangement. This clamping arrangement has at least two oppositely arranged clamping devices each having a clamping surface movable along a first axis between a clamping position and an open position. At the vibration welding position, i.e., when the first part in the upper tool and the second part in the lower tool or the stack of welded parts abut against each other, the clamping surfaces of the clamping devices move towards each other along the first axis so as to approach the clamping position. At this clamping position, the movement of the second part or the stack of welded parts is obstructed or prevented during vibration welding. In particular, the movement of the second part or the stack of welded parts with the first part is at least reduced to such an extent that a welding seam, preferably a welding seam of desired quality, is produced, if not eliminated. Preferably, the clamping surfaces of the clamping devices are locked in the clamping position so that they are fixedly arranged in the clamping position during vibration welding.

[0014] According to one alternative form, the clamping position is a fixed position. In another alternative form, the two oppositely arranged clamping devices operate with a trigger force to find the position of the stack of welded parts and approach the desired clamping position.

[0015] Furthermore, in one alternative form, the clamping position is the position where the clamping surface of the clamping device abuts directly against the second part or the stack of welded parts. According to another alternative form, the clamping position is the position where the clamping surface of the clamping device is offset by a short distance, for example 0.2 mm, from the second part or the stack of welded parts. The reason for the latter process of the procedure is that no additional stress is introduced into the stack of welded parts during vibration welding. Furthermore, the stack of welded parts is also not moved by the clamping arrangement, specifically the clamping surface of the clamping device. Finally, it should be noted that the clamping surface of the clamping device can be used for each layer of the stack of welded parts, or preferably, mainly in the region or part where the self-resonant frequency is generated. This will be described later with respect to the preferred embodiment.

[0016] Furthermore, it is preferable to arrange the clamping surface of one clamping device at a defined position relative to the second part or the stack of welded parts, for example by means of a servo motor. The defined position may be a position where a short distance, such as the aforementioned 0.2 mm, exists between the clamping surface and the second part or the stack of welded parts. On the opposite side of the second part or the stack of welded parts, the clamping surface of another clamping device applies a defined force. Also, it is preferable to use a pneumatic cylinder, for example, instead of a servo motor, to move the clamping surface of each clamping device.

[0017] After the vibration welding is completed, the clamping arrangement is released from the clamping engagement, and the second support body comprising the second tool, i.e., the lower tool, having the composite of the first and second parts or the increased stack of welded parts, moves to the initial position.

[0018] From this stage, especially when there is only a stack of the composite or only two parts, the above steps are repeated by placing another first part on the first tool, i.e., the upper tool. After the steps are repeated the desired number of times so that the desired stack exists, the user can remove the resulting stack of parts from the vibration welding device.

[0019] In this regard, especially when repeating the above steps, it must be considered that the stack of welded parts increases by only an additional part or layer in each cycle. Therefore, since the welding position, i.e., the distance between the first support and the second support, must be adjusted in each new cycle, the relative movement of the first support and the second support must be controlled very precisely. For example, the vibration welding position where the second support, i.e., the lifting table, approaches at the start is such that the first part and the second part abut against each other. After vibration welding, a stack of two parts, i.e., an increased stack of welded parts, is present in the lower tool. Here, another first part must be welded to the increased stack of welded parts, which newly forms the second part or the stack of welded parts. Since the distance between the first support and the second support is too short, the vibration welding position from the start cannot be used. Therefore, the vibration welding position must be adjusted by the thickness of the added part in each cycle. Specifically, the distance between the first support and the second support along the second axis must be increased accordingly. For this reason, it is particularly preferable to use a lifting table driven by an electric motor or hydraulics as the second support, because it can control the resulting movement very accurately.

[0020] One advantage of the vibration welding apparatus of the present invention is that the stress on the weld seam already present in the stack of welded parts is reduced during vibration welding. A further advantage is that the oscillation of the vibration welding head, and thus of the first part, can be kept constant and the self-resonant frequency can be avoided. Finally, it is advantageous that the vibration cycle time can be kept constant so that the processing time does not increase.

[0021] Since it was initially assumed that the vibration welding head oscillates only along the first axis in the first plane, the vibration welding apparatus having a vibration welding head that oscillates in the first plane, i.e., an orbital welding head, will be discussed below. In this case, it is particularly preferred to provide two further clamping devices, each of which also has a clamping surface. These further clamping devices are oriented such that their clamping surfaces obstruct or prevent the movement of the second part or the stack of welded parts along an axis in a first plane perpendicular to the first axis, for example, at the clamping position. Each axis is also referred to as a third axis. In other words, the clamping arrangement comprises four clamping devices and an angle of 90° is included between two adjacent clamping devices.

[0022] According to a preferred embodiment, the clamping arrangement of the vibration welding apparatus is fixed to a second support or the frame of the vibration welding apparatus. The advantage of fixing the clamping arrangement to the second support is that the clamping arrangement moves along the second axis together with the second support, specifically the lifting table. This increases the flexibility of the vibration welding apparatus. If the clamping arrangement is fixed to the frame, the clamping arrangement maintains its position independently of the movement of the second support, which reduces the effort of control.

[0023] Furthermore, according to another preferred embodiment, one or both of the clamping surfaces of at least two clamping devices are movable along a second axis. This mobility allows the position of the clamping surface along the second axis to be adjusted according to the thickness of the first component and / or the position of the second component or the stack of welded components. Thus, it can be ensured that the clamping surface only clamps the second component or the stack of welded components without interfering with the rocking or vibration of the first component. This mobility also allows for movement of the clamping surface along the Z-axis during and / or after vibration welding in certain preferred implementations. Thereby, the stack of welded components is stabilized during the stage where force is applied to the components to create a reliable welded connection after the movement of the vibration welding head has stopped.

[0024] Furthermore, it is advantageous for the vibration welding apparatus to comprise a plurality of clamping devices for the orbital welding head as described above, each clamping device providing a respective clamping surface. Furthermore, at least one, two, or preferably each clamping surface of the clamping devices is movable along a second axis. This embodiment enables the above-described advantages to be achieved also when a plurality of clamping devices are used in a clamping arrangement.

[0025] Finally, it is preferred for the vibration welding apparatus to comprise a preheating arrangement. Such a preheating arrangement allows the opposing sides of the first component and the second component or the stack of welded components to be preheated so that the characteristics of the resulting weld seam are further improved. Specifically, the generation of loose particles during the initial stage of subsequent vibration welding can be reduced by preheating the respective welding structures.

[0026] For each step of the procedure in the case of preheating, after the first part is placed on the first tool, i.e., the upper tool, the lifting table returns to the intermediate position along the second axis, and at the intermediate position, the preheating arrangement can be moved from the standby position to the preheating position between the parts. After the preheating arrangement is placed between the two parts, the two parts are preheated at the location where they will be welded. After preheating, the preheating arrangement is returned from the preheating position to the standby position. Then, the lifting table moves to the vibration welding position along the second axis as described above.

[0027] The vibration welding method of the present invention using the vibration welding apparatus according to the present invention includes the steps of placing a first part on a first tool, moving a second part or a second support having a stack of welded parts along a second axis to a vibration welding position relative to the first support, moving the clamping surfaces of at least two oppositely arranged clamping devices along a first axis to a clamping position so that the movement of the second part or the stack of welded parts along at least the first axis is obstructed, then vibration welding the first part to the second part or the stack of welded parts so that an increased stack of welded parts is produced, then moving the clamping surfaces along the first axis to an open position, and then returning the second support to the initial position. By the vibration welding method of the present invention using the vibration welding apparatus of the present invention, a stack of parts having a welded seam of desired quality can be produced by a reliable process method even in the case of a stack of parts having a specific height or number of layers. The vibration welding method of the present invention refers to the above description regarding the technical effects and advantages since the vibration welding apparatus of the present invention is used.

[0028] In a preferred embodiment of the vibration welding method, the step of placing the first part on the first tool includes placing the first part on the second tool, preferably on top of the second part or a stack of welded parts, and moving a second support having the first part from an initial position to a transfer position along a second axis relative to the first support. By these method steps, the user places the first part on the second tool, and the second tool then moves to transfer the first part to the first tool. This eliminates the manual step of placing the first part on the first tool.

[0029] Furthermore, the step of moving the clamping surfaces to the clamping position preferably includes moving the first clamping surface in a first direction along a first axis and moving the second clamping surface, which is arranged opposite, in a second direction opposite to the first direction along the first axis, and the step of moving the clamping surfaces to the open position preferably includes moving the first clamping surface in the second direction along the first axis and moving the second clamping surface, which is arranged opposite, in a first direction opposite to the second direction along the first axis.

[0030] In this regard, as explained above, it must be noted that the two oppositely arranged clamping devices can also operate with a trigger force to find the position of the stack of welded parts. Furthermore, the clamping position can be either a position where the clamping surfaces of the clamping device directly abut against the second part or the stack of welded parts, or a position where the clamping surfaces of the clamping device are offset by a short distance, for example 0.2 mm, from the second part or the stack of welded parts. In either case, it is preferred to lock the clamping surfaces in this position. The reason for the clamping position where the clamping surfaces are offset by a short distance is that no additional stress is introduced into the stack of welded parts during vibration welding, especially. Furthermore, the stack of welded parts is also not moved by the clamping arrangement, specifically the clamping surfaces of the clamping device.

[0031] Also, when at least one, preferably each clamping surface of the clamping device is movable along the second axis, it is advantageous for the vibration welding method that the end of each clamping surface adjacent to the upper tool is arranged at the clamping position adjacent to the end of the stack of the second part or welded parts that abuts against the first part or is adjacent thereto. It is possible thereby for the clamping device to be used for each layer of the stack of welded parts or preferably in the region or part where the self-resonant frequency mainly occurs.

[0032] Furthermore, when the vibration welding device comprises a preheating arrangement, it is preferable for the vibration welding method to include a further step of moving the second support to a preheating position relative to the first support after the step of arranging the first part on the first tool and before the step of moving the second support to the vibration welding position, a step of moving the preheating arrangement from the standby position to the preheating position between the first tool and the second tool, a step of preheating the first part and the second part or the stack of welded parts, and a step of moving the preheating arrangement from the preheating position to the standby position. Thereby, in combination with the preferred embodiment of the vibration welding device of the present invention, the effective preheating described above can be achieved.

[0033] The retrofit kit of the present invention for a vibration welding device having a vibration welding head that vibrates in a first plane during use, preferably only along a first axis, comprises a clamping arrangement having at least two clamping devices each having a clamping surface movable along the first axis between a clamping position and an open position so as to be able to impede the movement of at least the second part or the stack of welded parts along the first axis during vibration welding at the clamping position. With the retrofit kit, a clamping arrangement can be installed on a general vibration welding device. As a result, after adapting the control method, the vibration welding device realizes the technical effects and advantages of the vibration welding device of the present invention described above. Therefore, in order to avoid unnecessary repetition, the above description is referred to.

[0034] In a preferred embodiment of the retrofit kit, at least one clamping surface is movable along a second axis perpendicular to the first plane. This combination further increases the flexibility of the resulting vibration welding device, as discussed above.

[0035] The retrofit method of the present invention for a vibration welding device includes the steps of providing the retrofit kit of the present invention, fixing a clamping device to a lifting table or a frame of the vibration welding device such that at least two clamping surfaces are arranged opposite to each other, and implementing the clamping device in a control method of the vibration welding device. As a result, the retrofit method can improve a general vibration welding device to achieve the technical effects and advantages of the vibration welding device of the present invention described above.

[0036] 4. Brief Description of the Drawings Hereinafter, the present invention will be described in detail based on the drawings. In the drawings, the same reference numerals denote the same elements and / or components.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0038] 5. Detailed Description of Preferred Embodiments An embodiment of the vibration welding apparatus 1; 100 of the present invention will be described below, particularly with regard to its function. Generally, the vibration welding apparatus can be used in the automotive industry, the energy industry, or medical technology. In particular, it can be used in any application where parts, preferably plastic parts, have to be welded in a reliable manner by vibration welding to a stack of already welded parts, preferably a stack of already welded plastic parts.

[0039] Referring now to FIGS. 1 to 6, a first embodiment of the vibration welding apparatus 1 and its function are described. The vibration welding apparatus 1 comprises a first tool which is an upper tool 10 having a vibration welding head arranged on a first support. The vibration welding head of the upper tool 10 defines a vibration welding plane or a first plane and, during use, oscillates or vibrates at least along a first axis X. Instead of the upper tool 10 having a vibration welding head that vibrates only within the first plane along one axis, i.e., the first axis X, it is also possible to use an upper tool having an orbital vibration welding head. In this case, the vibration welding head will perform a circular motion within the first plane, which can be described by the first axis X and a further axis Y perpendicular to the first axis X.

[0040] Referring now to FIG. 1, the vibration welding apparatus 1 also includes a second tool, which is a lower tool 12 disposed on a second support. The first support and the second support, and thus the upper tool 10 and the lower tool 12, are movable relative to each other at least along a second axis Z. The second axis Z is perpendicular to the first plane.

[0041] Regarding this embodiment, the first support of the vibration welding apparatus 1 is an upper mounting plate, and the second support is a lifting table, preferably a lifting table driven by an electric motor or a hydraulic pressure. In particular, precise control that facilitates the vibration welding method can be achieved by an electric motor or a hydraulic pressure.

[0042] Furthermore, the vibration welding apparatus 1 has a clamping arrangement including at least two oppositely disposed clamping devices 14. Each clamping device 14 provides a clamping surface 16. In the illustrated embodiment, the clamping arrangement is fixed to a frame (not shown). Thus, the clamping arrangement does not move automatically with the first or second support. For easier understanding, the vibration welding apparatus 1 configured as such during use will be described.

[0043] First, as seen in FIG. 1, the upper tool 10 and the lower tool 12, and thus the first support and the second support, are in an initial position that is sufficiently separated from each other so that a user can place the first part 3 on top of the second part or the stack 5 of welded parts. As shown, a stack 5 of two welded parts is present on the lower tool 12. The first part 3 is disposed on top of the stack 5 of welded parts within the lower tool. Further, the clamping surfaces 16 of the clamping devices 14 of the clamping arrangement are in an open position.

[0044] In the next step, the second support, and thus the lower tool 12, is moved along the second axis Z in the direction of the upper tool 10 until the transition position is reached. At this transition position, the first part 3 is received by the upper tool 10. For example, the first part 3 is held by the upper tool 10 under pressure or the like. Thus, the upper tool 10 serves to receive the first part 3, and the lower tool 12 serves to receive the second part or the stack 5 of welded parts. The clamping surface 16 is still in the open position. This state is shown in FIG. 2.

[0045] Thereafter, the lower tool 12 and the second support are moved along the second axis Z to an intermediate position away from the upper tool 10. If the first part 3 is placed directly on the upper tool 10 manually or by a further device, for example, then the movement of the lower tool 12 to the intermediate position is not necessary.

[0046] Nevertheless, since the vibration welding device 1 generally also comprises an optional preheating arrangement 18, the lower tool 12, and thus the second support, is moved to the intermediate position. Thereafter, the preheating arrangement 18 is moved from the standby position to a preheating position between the upper tool 10 and the lower tool 12 in the intermediate position. FIG. 3 shows this stage of the process. As can be seen, the position of the clamping surface 16 has not changed, and as a result, it is in the open position.

[0047] After the first part 3 and the stack 5 of welded parts have been preheated, the preheating arrangement 18 is returned from the preheating position to the standby position. The respective preheating arrangements having, for example, IR radiators and their configurations are generally known and are not described in detail herein.

[0048] As soon as the preheating arrangement 18 has reached its standby position, the lower tool 12 can be moved to the vibration welding position relative to the upper tool 10. As can be seen in FIG. 4, in this position, the first part 3 and the stack 5 of welded parts abut against each other.

[0049] Furthermore, with respect to FIG. 4, the two oppositely arranged clamping surfaces 16 are moving relative to each other along a first axis X so as to directly abut against and clamp a stack 5 of welded parts arranged on the lower tool 12. Thus, the clamping arrangement is moving from an open position to a clamping position, in which the movement of the stack 5 of welded parts is impeded or blocked at least along the first axis X during vibration welding. In particular, the movement of the stack 5 of welded parts with the first part 3 is at least reduced to the extent that a weld seam of desired quality is produced, if not eliminated.

[0050] In this regard, it must first be noted that, as described above, the clamping arrangement of the vibration welding apparatus is fixed to the frame of the vibration welding apparatus. Thus, the position of the clamping surfaces of the clamping arrangement along the second axis Z is predetermined and adapted to a specific first part 3. This reduces the control effort.

[0051] As an alternative, the clamping device 14 may be fixed to a second support. In this case, the clamping device, and thus the clamping arrangement, moves with the second support. When using this alternative form, it must be ensured that the clamping surface 16 abuts only against the second part or the stack 5 of welded parts during use. Otherwise, the movement of the first part 3 would also be impeded, which would prevent vibration welding. To avoid this, the clamping arrangement may be adapted to be used only when the stack 5 of welded parts already has a specific height. Alternatively, mobility of the clamping surface 16 along the second axis Z may be further provided. In particular, mobility of the clamping surface 16 along the second axis Z, preferably of each clamping surface 16, is preferred and advantageous. The latter will be discussed with respect to a second embodiment of the vibration welding apparatus 100.

[0052] The advantage of fixing the clamping arrangement to the second support is that the clamping arrangement moves along the second axis Z with the second support, specifically the lifting table. This increases the flexibility of the vibration welding apparatus 1.

[0053] It is also pointed out that in order to achieve perfection, when the clamping arrangement is fixed to the frame, further mobility of the clamping surface 16 along the second axis Z can be provided. Thereby, the vibration welding device 1 can be adapted to the processing of other parts without the need to remove the clamping arrangement and fix it in a new position of the frame.

[0054] Furthermore, it must be noted that the two oppositely arranged clamping devices 14 can operate with a trigger force to find the position of the stack 5 of welded parts, instead of approaching the clamping position as a fixed position. Furthermore, the clamping position can be either a position where the clamping surface 16 directly abuts against the second part or the stack 5 of welded parts, or a position where the clamping surface 16 is offset by a short distance, for example 0.2 mm, from the second part or the stack 5 of welded parts. In either case, the clamping surface 16 is preferably locked.

[0055] When the clamping surface 16 is offset by a short distance, additional stress is not introduced into the stack 5 of welded parts during vibration welding, especially. Furthermore, the stack 5 of welded parts is also not moved by the clamping arrangement, specifically the clamping surface 16 of the clamping device 14. Finally, it must be noted that the clamping surface 16 of the clamping device 14 can be used for each layer of the stack 5 of welded parts, or preferably, mainly in the region or part where the self-resonant frequency is generated.

[0056] During vibration welding, the upper tool 10 preferably moves only along the first axis X. The movement of the stack 5 of welded parts along this axis X by the clamping surface 16 of the clamping device 14 is obstructed or prevented as described above.

[0057] If the upper tool 10 is an orbital welding tool that moves not only along the first axis X but also within the vibration welding plane or the first plane, it is preferably provided with two further clamping devices 14 in a clamping arrangement, each of which has a respective clamping surface 16. The further clamping devices 14 face each other and are arranged such that they impede or prevent the movement of a second component or a stack 5 of welded components along an axis Y that is at least perpendicular to the first axis X but lies within the first plane. Each axis Y is also referred to as a third axis Y.

[0058] After the vibration welding is completed, the clamping surfaces 16 are moved from the clamping position to the open position, and a second support with a second tool, i.e., a lower tool 12, having an increased stack 20 of welded components is moved to the initial position. This can be seen in Figure 6.

[0059] Here, the above step is repeated by placing another first component 3 on the first tool, i.e., the upper tool 10. The increased stack 20 of welded components present in the lower tool 12 thus forms a new stack 5 of welded components. After the step has been repeated a desired number of times such that a desired stack is present, the user can remove the resulting, i.e., the final stack 5 of welded components, from the vibration welding apparatus 1.

[0060] When proceeding in this way, especially when repeating the above step, it must be considered that the stack 5 of welded components increases preferably by only a further component 3 or layer made of plastic in each cycle. Therefore, since the distance between the first support and the second support, i.e., the vibration welding position, must be adjusted in each new cycle, the relative movement of the first support and the second support must be controlled very precisely.

[0061] At the start, the vibration welding position where the second support, i.e., the lifting table approaches, is such that the first part 3 and the second part 5 abut against each other. After vibration welding, the stack of the two parts, i.e., the increased stack 20 of the welded parts, is present in the lower tool. Here, another first part 3 has to be welded to the increased stack 20 of the welded parts, which forms the stack 5 of the second part or the welded parts in this new cycle. Since the distance between the first support and the second support is too short, therefore, the vibration welding position from the start cannot be used. Therefore, the vibration welding position has to be adjusted by the thickness of the additional part 3 in each cycle. Specifically, the distance between the first support and the second support along the second axis Z has to be increased accordingly. For this reason, it is particularly preferred to use a lifting table driven by an electric motor or hydraulics as the second support, because it can control the resulting movement very precisely.

[0062] One advantage of the vibration welding device 1 of the present invention is that the stress on the weld seam already present in the stack 5 of the welded parts is reduced during vibration welding. A further advantage is that the oscillation of the vibration welding head, and thus of the first part 3, can be kept constant and the self-resonant frequency can be avoided. Finally, it is advantageous that the vibration cycle time can be kept constant so that the processing time does not increase.

[0063] In FIGS. 7 to 9, an alternative embodiment of the vibration welding device 100 of the present invention is shown. Generally, the configuration of the vibration welding device 100 is the same as that of the above-described vibration welding device 1. Nevertheless, in contrast to the above embodiment, here the clamping surface 116 of the clamping device 114 is further movable along the second axis Z. This applies regardless of whether the clamping device 114 is fixed to the frame or to the second support.

[0064] This mobility enables the position of the clamping surface 116 along the second axis Z to be adjusted according to the thickness of the first part 103 and / or the position of the second part or the stack 105 of welded parts. Thus, it can be ensured that the clamping surface 116 only clamps the second part or the stack 105 of welded parts without interfering with the rocking or vibration of the first part 103. Thus, this mobility also allows movement of the clamping surface 116 along the Z axis during and / or after vibration welding in certain preferred implementations. Thereby, in particular, the stack 105 of welded parts is stabilized during the post-vibration welding stage when forces are applied to the parts 103, 105 to create a reliable welded connection.

[0065] Referring now to FIG. 10, embodiments of each vibration welding method are described. In a first step A, the first part 3; 103 is placed on the first tool. This can be done directly by the user. As an alternative, this step A of placing the first part 3; 103 on the first tool includes steps A1 and A2. In step A1, the first part 3; 103 is placed on a second tool, preferably on top of the second part or the stack 5; 105 of welded parts. In a subsequent step A2, the second support 109 having the first part 3; 103 is moved from an initial position to a transfer position along the second axis Z relative to the first support 107. By these method steps, the user places the first part 3; 103 on the second tool, which then moves to transfer the first part 3; 103 to the first tool. This eliminates the manual step of placing the first part 3; 103 on the first tool.

[0066] Thereafter, especially when the vibration welding apparatus 1; 100 includes a preheating arrangement 18, the method includes further steps H to K. In step H, the second support 109 is moved to an intermediate position relative to the first support 107. This step may also be performed independently of the presence of the preheating arrangement 18 to ensure that the first part 3; 103 is firmly held in the first tool, i.e., the upper tool 10; 110.

[0067] Next, in step I, the preheating arrangement 18 is moved from the standby position to the preheating position between the first tool and the second tool. In step J, the first part 3; 103 and the stack 5; 105 of the second part or the welded parts are preheated. After preheating, in step K, the preheating arrangement is moved from the preheating position to the standby position. By this process, effective preheating can be achieved.

[0068] After preheating, in step B, the second support 109 having the stack 5; 105 of the second part or the welded parts is moved along the second axis Z with respect to the first support 107 to the vibration welding position.

[0069] At the vibration welding position where the first part 3; 103 and the stack 5; 105 of the second part or the welded parts abut, an optional step G may be performed. The requirement of this step is that at least one, preferably the clamping surfaces 16; 116 of each clamping device 14; 114, are movable along the second axis Z. This movement is independent of the fixing of the clamping device 14; 114 to the frame or the second support 109, that is, for example, independent of the movement of the clamping arrangement and the second support 109. Since the clamping surfaces 16; 116 are particularly movable along the second axis Z with respect to the clamping device 14; 114, on the contrary, it provides an additional degree of freedom to the clamping surfaces 16; 116 provided by the clamping device 14; 114.

[0070] Thereby, in step G, the movement of the clamping surfaces 16; 116 of one, two, or preferably each clamping device 14; 114 along the second axis Z is such that the end of each clamping surface 116 adjacent to the upper tool 10; 110 abuts the end of the stack 5; 105 of the second part or the welded parts that abuts the first part 3; 103, or is arranged at a clamping position adjacent thereto. This is shown, for example, in FIGS. 4, 8, and 9.

[0071] As a result, the clamping surfaces 16; 116 abut against a stack 5; 105 of welded parts that are directly adjacent to the first part 3; 103. This effectively stabilizes the stack 5; 105 of parts without interfering with the movement of the first part 3; 103 during vibration welding. In general, it is possible for the clamping surfaces 16; 116 to be used for each layer of the stack 5; 105 of welded parts, or preferably, mainly in the region or part where the self-resonant frequency occurs, due to the mobility of the clamping surfaces 16; 116 along the second axis Z. Furthermore, the position of the clamping surfaces 16; 116 can be adapted to the thickness of the first part 3; 103 in an easy way.

[0072] After the position of the clamping surfaces 16; 116 along the second axis Z has been adjusted, the movement of the clamping surfaces 16; 116 of at least two oppositely arranged clamping devices 14; 114 to the clamping position along the first axis X is carried out in step C. As a result, the movement of the second part or the stack 5; 105 of welded parts is obstructed at least along the first axis X.

[0073] Preferably, the above step C consists in particular of steps C1 and C2. In step C1, the movement of the first clamping surface 16; 116 in a first direction along the first axis X is carried out, while before, after or simultaneously with step C1, the movement of the oppositely arranged second clamping surface 16; 116 in a second direction along the first axis X, opposite to the first direction, is carried out in step C2. For example, if there are two further clamping devices arranged opposite each other and their clamping surfaces 16; 116 are movable along the third axis Y (see above), their movement is further carried out in a manner similar to stabilizing the stack 5; 105 of welded parts. This is particularly preferred when the vibration welding device comprises an orbital vibration welding head.

[0074] In this regard, it should be noted that the opposing clamping devices 14; 114 can also be operated by a trigger force to find the position of the stack 5; 105 of welded parts. Further, the clamping position is the position where the clamping surfaces 16; 116 directly abut against the second part or the stack 5; 105 of welded parts. Alternatively, the clamping position is the position where the clamping surfaces 16; 116 are offset from the second part or the stack 5; 105 of welded parts by a short distance, for example, 0.2 mm. In either case, the clamping surfaces 16; 116 are preferably locked in the clamping position.

[0075] After the clamping devices 14; 114 are arranged in the clamping position, the vibration welding of the first part 3; 103 to the second part or the stack 5; 105 of welded parts is performed in step D. After the vibration welding is completed, an increased stack 20 of welded parts thus exists. Preferably, after the movement of the vibration welding head stops, a force is applied to the increased stack 20 of welded parts so that a reliable welded connection is produced. Specifically, by waiting for a predetermined holding time under the application of force, recrystallization of the materials of the parts 3, 5; 103, 105 becomes possible.

[0076] Furthermore, after the vibration welding is finished, in step E, the movement of the clamping surfaces 16; 116 to the open position along the first axis X is performed. Similar to step C, step E may also include two steps E1 and E2. Specifically, in step E1, the movement of the first clamping surface 16; 116 in the second direction along the first axis X is performed, while before, after, or simultaneously therewith, in step E2, the movement of the second clamping surface 16; 116 arranged oppositely in the first direction opposite to the second direction along the first axis X is performed.

[0077] Thereafter, in step F, the second support 109 is returned to its initial position. Here, the above method steps can be repeated until the resulting stack 20 of parts reaches the desired height or number of layers. As described above, especially with respect to the vibration welding position, taking into account the transfer position and the intermediate position as well, the new height of the stack 5; 105 of welded parts must be considered as it approaches each position.

[0078] An embodiment of the retrofit kit of the present invention for a vibration welding apparatus having a vibration welding head that vibrates only in a first plane during use, preferably along a first axis, comprises a clamping arrangement having at least two clamping devices 14; 114 each having a clamping surface 16; 116 movable along a first axis X between a clamping position and an open position, such that, in the clamping position, movement of at least a second part or a stack 5; 105 of welded parts along the first axis X can be impeded during vibration welding. Further, at least one clamping surface 16; 116 is preferably movable along a second axis Z perpendicular to the first plane. With the retrofit kit, a clamping arrangement can be provided to a general vibration welding apparatus, such that, after adapting the control method, the vibration welding apparatus realizes the technical effects and advantages of the vibration welding apparatus 1; 100 of the present invention described above.

[0079] Finally, with reference to FIG. 11, an embodiment of the retrofit method of the present invention for a vibration welding apparatus will be discussed. First, in step i, the retrofit kit of the present invention is provided. Next, in step ii, the clamping devices 14; 114 are fixed to the lifting table or frame of the vibration welding apparatus such that the clamping surfaces 16; 116 are arranged opposite each other. Finally, in step iii, the implementation of the clamping devices 14; 114 in the control method of the vibration welding apparatus is performed. As a result, the retrofit method can improve a general vibration welding apparatus to realize the technical effects and advantages of the vibration welding apparatus 1; 100 of the present invention described above.

Explanation of Reference Signs

[0080] 6. List of Reference Signs 1 Vibration welding device 3 First component 5 Second component or stack of welded components 10 Upper tool 12 Lower tool 14 Clamping device 16 Clamping surface 18 Preheating arrangement 20 Increased stack of welded components 100 Vibration welding device 103 First component 105 Second component or stack of welded components 107 First support 109 Second support 110 Upper tool 112 Lower tool 114 Clamping device 116 Clamping surface X First axis Z Second axis

Claims

1. A retrofit kit for a vibration welding apparatus for welding a first component (3; 103) to a second component or a stack of welded components (5; 105), said vibration welding apparatus having, in use, a vibration welding head that vibrates along a first axis X within a first plane, said retrofit kit having, in a clamping position, at least two clamping devices (14; 114) each having a clamping surface (16; 116) movable along the first axis X between the clamping position and an open position so as to be able to interfere with the movement of the second component or the stack of welded components (5; 105) along the first axis X during vibration welding. A retrofit kit comprising a clamping arrangement.

2. The retrofit kit according to claim 1, wherein at least one clamping surface (16; 116) is movable along a second axis Z perpendicular to the first plane.

3. A retrofit method for a vibration welding apparatus, comprising: providing (step i) the retrofit kit according to claim 1 or 2; fixing (step ii) the clamping device (14; 114) to the lifting table or frame of the vibration welding apparatus such that the at least two clamping surfaces are arranged opposite each other; implementing (step iii) the clamping device (14; 114) in the control method of the vibration welding apparatus; A retrofit method comprising.

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