DE102018102264B4 - Process for producing a plastic component and device for carrying out the process - Google Patents

Abstract

Method for producing a plastic component, with the method steps: - providing an add-on element (6), such as a functional unit, a reinforcing element; - heating a connection area (10) of the add-on element (6); - holding the heated add-on element (6) in a holding position, wherein the heated add-on element (6) has a distance (a) to a contact surface (14) in the holding position;- reducing the distance (a) between the contact surface (14) and the heated add-on element (6) using a lifting device (12); - Welding the heated add-on element (6) to a wall element (18) of the plastic component by pressing the heated add-on element (6) against the wall element (18), the heated add-on element (6) being on a side facing away from the wall element (18) during the welding (20) rests against the contact surface (14) at least in sections.

Description

The present invention relates to a method for producing a plastic component and a device for carrying out the method.

When hybrid vehicles are driven electrically, the plastic fuel tank, which stores liquid fuel, is closed to avoid fuel emissions. When closed, the internal pressure of the fuel tank can be between -150 mbar and +450 mbar depending on the temperature.

As a result of the pressure load, the plastic wall of the fuel tank can curve outwards or inwards by several centimetres. These deformations can lead to damage to the wall of the fuel tank or to functional units accommodated in the fuel tank or connected to the fuel tank. Furthermore, additional installation space must be reserved so that a deformed wall neither extends below the ground clearance line of a motor vehicle nor is it pressed against the body.

In order to reduce the deformation of a wall of a plastic fuel tank as a result of temperature-related internal pressure fluctuations, the plastic wall can be reinforced locally. For this purpose, for example, reinforcement elements made of fiber-reinforced plastic can be used, which are welded to the tank wall.

When welding add-on elements to such a plastic wall of a plastic fuel tank, the fundamental challenge is to integrate the application of the add-on elements as efficiently as possible into the manufacturing process. If, for example, preheated, flat reinforcement elements are to be welded using the heat of extrusion of the preforms in the half-shell blow molding process, cooling of the preheated, flat reinforcement element before welding must be avoided in order to achieve a reliable material connection. This applies both to reinforcement elements and to other functional units, such as structures for reducing sloshing noises, heating elements and the like, which are to be welded to a container wall.

Relevant prior art can be found in DE 102010056032 A1 , DE 69302760 T2 and JP H04-12824 A1 .

Against this background, the invention is based on the technical problem of specifying a method for producing a plastic component and a device for carrying out the method, which do not have the disadvantages described above, or at least do so to a lesser extent, and in particular allow add-on elements to be reliably welded to a wall element , whereby cooling of an attachment to be welded is avoided before welding.

The technical problem described above is solved in each case by a method according to claim 1 and a device according to claim 16. Further refinements of the invention result from the dependent claims and the following description.

• - Bereitstellen eines Anbauelements, wie einer Funktionseinheit, eines Verstärkungselements, oder dergleichen;
• - Erwärmen eines Verbindungsbereichs des Anbauelements;
• - Halten des erwärmten Anbauelements in einer Halteposition, wobei das erwärmte Anbauelement in der Halteposition einen Abstand zu einer Anlagefläche aufweist;
• - Verringern des Abstands zwischen der Anlagefläche und dem erwärmten Anbauelement mithilfe einer Hubvorrichtung;
• - Verschweißen des erwärmten Anbauelements mit einem Wandungselement des Kunststoffbauteils durch Andrücken des erwärmten Anbauelements an das Wandungselement, wobei das erwärmte Anbauelement während des Verschweißens mit einer dem Wandungselement abgewandten Seite zumindest abschnittsweise an der Anlagefläche anliegt.

According to a first aspect, the invention relates to a method for producing a plastic component, with the method steps:

• - Providing an add-on element, such as a functional unit, a reinforcing element, or the like;
• - heating a connection area of the add-on element;
• - Holding the heated add-on element in a holding position, the heated add-on element being at a distance from a contact surface in the holding position;
• - Reducing the distance between the contact surface and the heated attachment using a lifting device;
• - Welding the heated add-on element to a wall element of the plastic component by pressing the heated add-on element against the wall element, the heated add-on element resting against the contact surface at least in sections during the welding with a side facing away from the wall element.

Because the heated add-on element is initially held at a distance from the contact surface, heat dissipation from the heated add-on element via the contact surface in the holding position can be avoided. In particular, it can be provided that the add-on element has no contact with the contact surface in the holding position.

Before and/or during the welding, the distance between the contact surface and the heated add-on element is reduced. Accordingly, a first contact of the connection area with the wall element can already take place before the heated add-on element rests at least in sections on the contact surface with the side facing away from the wall element. Alternatively, a first ter contact of the connection area with the wall element only takes place after the heated add-on element rests at least in sections on the contact surface with the side facing away from the wall element.

When a connection area of the add-on element is heated in the present case, this is heating to a temperature that enables the plastic of the add-on element to be welded to a plastic of the wall element. After heating, the connection area of the add-on element is in an at least partially plasticized state.

It goes without saying that at least the connection area of the add-on element is heated, but according to further configurations of the invention it can also be provided that the entire add-on element is heated. If the add-on element is, for example, a thin-walled, flat reinforcement element, such as an organo sheet, a fiber-reinforced tape or the like, the entire reinforcement element is heated through when the thin-walled, flat reinforcement element is heated. For example, such a thin-walled, planar reinforcement element can have a thickness of 0.2 to 3 mm and a planar extent of 0.01 m ² to 1 m ² .

According to a further embodiment of the method, it is provided that the heated add-on element is pressed against the wall element with the aid of a mechanical pressing device in order to cause the add-on element to be welded to the wall element. Accordingly, the heated add-on element can be welded to the wall element, for example by bringing at least one pressure stamp into contact with the add-on element or the wall element in order to mechanically press the add-on element and the wall element against one another.

If, for example, the heated add-on element is mechanically pressed against or against the wall element within a blow mold, the welding can take place in particular before blowing pressure is applied, in which case ambient pressure prevails in the ambient air surrounding the add-on part and the wall element during the welding.

Alternatively or in addition to using a mechanical pressing device, the heated component can be pressed against the wall element in a blow molding process by applying pressure to the wall element and/or the heated component with blowing pressure, which brings the wall element and the heated add-on element into contact in order to close them weld.

However, the welding is preferably achieved solely by mechanically pressing the heated add-on element onto the wall element using at least one pressure stamp or a plurality of pressure stamps in order to repeatedly achieve a defined weld between the add-on element and the wall element.

According to a further embodiment of the method, it is provided that the distance between the add-on element and the contact surface is 50 mm or less in the holding position. In this way, the add-on element can be quickly brought into contact with the contact surface against which the add-on element is pressed during welding.

Depending on the temperature behavior of the add-on element, further refinements of the method can provide that the distance between the add-on element and the contact surface in the holding position is 30 mm or less, 20 mm or less, or 10 mm or less.

Alternatively or additionally, the distance between the add-on element and the contact surface in the holding position can be 5 mm or more. This can prevent folds that may have formed on the add-on element as a result of the heating in the holding position from coming into contact with the contact surface. If the add-on element is, for example, a flat reinforcement element, such as a fiber-reinforced organo sheet, a fiber-reinforced tape fabric or the like, such a flat reinforcement element can form folds as a result of the heating, which are curved at least in sections in the direction of the contact surface.

The minimum distance that an add-on element should have from the contact surface in the holding position can therefore be selected as a function of the expected change in the geometry of the add-on element as a result of the heating. For example, a distance from the contact surface of 1 mm or more, or 2 mm or more, can be specified for an add-on part in which only minor deformations are to be expected as a result of the heating.

Accordingly, for the holding position on the one hand a maximum distance of the add-on element to the contact surface and on the other hand alternatively or in addition, a minimum distance of the add-on element to the contact surface can be specified.

The distance is measured in particular perpendicular to the contact surface in the direction of the side facing away from the wall element.

In order to prevent the heated add-on element from cooling down to a temperature below that required for reliable welding, a further embodiment of the method provides that a contact period during which the heated add-on element is in contact with the contact surface before it comes into contact with the wall element is five seconds or less.

In order to prevent the heated add-on element from cooling down to below the temperature required for reliable welding, a further embodiment of the method provides that a contact period during which the heated add-on element is in contact with the contact surface before it comes into contact with the wall element is 2 seconds or less.

In order to prevent the heated add-on element from cooling down to a temperature below the temperature required for reliable welding, according to a further embodiment of the method it is provided that a contact period during which the heated add-on element is in contact with the contact surface before it comes into contact with the wall element is one second or less.

The contact time can be selected according to the cooling behavior of the attachment to be connected to the wall element. If, for example, a thin-walled, flat reinforcement element is to be welded to the wall element, it may be necessary for a contact time during which the thin-walled, flat reinforcement element is in contact with the wall element to be 1 second or less to be 0.5 seconds or less or is 0.25 seconds or less. If, on the other hand, a several centimeters thick, randomly cross-linked, spongy structure is heated locally in its connection area, no significant cooling effect is to be expected from the contact of the side facing away from the connection area with the contact surface. In such a case, for example, a contact time period on the contact surface can be up to 5 seconds without impairing the quality of the material connection achieved by welding.

According to a further embodiment, it is provided that the add-on element is welded to an outside of the wall element facing a forming tool, with a tool surface forming the contact surface for shaping the wall element. The molding tool can be a blow molding tool, for example.

Alternatively, it can be provided that the add-on element is welded to an inner side of the wall element facing away from a mold, with a surface of a pressure stamp forming the contact surface, which is held on a central frame.

When a center frame is mentioned here, it is in particular a movable frame that can be moved between mold halves of a mold in order to apply functional units and/or to position add-on parts.

Provision can be made for two or more add-on elements to be welded to the wall element.

According to a further embodiment of the method, it is provided that at least one add-on element is welded to the inside of the wall element and at least one further add-on element is welded to the outside of the wall element.

Several add-on elements can be welded on the outside of the wall element and several add-on elements can be welded on the inside of the wall element.

In order to achieve the lowest possible heat dissipation from the heated add-on element, according to a further embodiment of the method it is provided that the heated add-on element is held in a holding position with the aid of a holding device which holds the heated add-on part in the holding position with at least one holding element or a plurality of holding elements , wherein a contact surface of the holding device to the heated add-on element is less than 10% of a surface of the connection area to be welded.

Furthermore, it can be provided that the contact surface of the holding device to the heated add-on element is less than 5% of a surface of the connection area to be welded, in particular less than 2% of a surface of the connection area to be welded, in order to prevent the heated add-on element from cooling down by the system to keep the contact surface small.

Alternatively or additionally, it can be provided that the holding device has a heating device in order to heat a contact surface of the holding device with the heated add-on element and to counteract heat dissipation from the heated add-on element.

According to a further embodiment of the method, it can be provided that the holding device has at least one holding element which, starting from the holding position, can be moved into a pressing position, the holding element being arranged flush with the contact surface in the pressing position or being set back with respect to the contact surface.

In particular, a holding element of the holding device or the holding elements of the holding device can be detached from the attachment element as soon as the attachment element first adheres to the wall element. Alternatively or additionally, a holding element of the holding device or the holding elements of the holding device can remain in contact with the add-on element and hold the add-on element during the entire duration of the welding process.

Provision can be made for at least one holding element to be a vacuum suction cup which has a rigid suction surface for holding the add-on element. In particular, several vacuum suction cups can be provided, each of which has a rigid suction surface for holding the add-on element. The use of one or more vacuum suction cups has the advantage that the add-on element is not damaged by contact with the holding device. In addition, a vacuum suction cup can be detached quickly and easily from the add-on element.

When a rigid suction surface is mentioned here, it is a suction surface that is not limp under its own weight in the unloaded state.

The rigid suction surface can consist of a metallic material and/or a sintered material, for example. In particular, a suction element on which the rigid suction surface is formed can have a porous material or consist of a porous material, so that a negative pressure for sucking in the add-on element can be provided via the pores of the material on the suction surface.

The rigid suction surface can be formed from a coated plastic whose melting point is above the temperature to which the attachment is heated, so that plasticization of the suction surface can be avoided.

Alternatively or additionally, it can be provided that at least one holding element is a needle or a mandrel. The needle or the mandrel of such a holding element can partially or completely penetrate the attachment element, so that a form-fitting connection is formed between the holding element and the attachment element. It is advantageous that such a holding element can be provided inexpensively and, for example in comparison to the vacuum suction device described above, means less investment.

Alternatively or additionally, it can be provided that at least one holding element is a gripper. The gripper can partially or completely grip or encompass the add-on element in order to hold the add-on element in a non-positive and/or positive manner. The use of a gripper has the advantage that various add-on elements that differ in their geometry can be held using one and the same gripper. For example, this means that no conversion of a production facility is required for handling and moving different add-on elements.

According to a further embodiment of the method, it is provided that the add-on element has a reinforcement element, such as an organo sheet, a fiber-reinforced tape or the like. Alternatively, it can be provided that the add-on element consists of a reinforcement element, such as an organo sheet, a fiber-reinforced tape or the like.

The organic sheet and/or fiber-reinforced tape can have fibers made of glass, carbon, aramid or basalt.

The organo sheet and/or fiber-reinforced tape can have a matrix material made of polyamide (PA), polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), polyetheretherketone (PEEK), polybutylene terephthalate (PBT), acrylonitrile butadiene styrene copolymer (ABS), polyphthalamide (PPA).

The organo sheet can be a woven fabric or a non-crimp fabric.

The tape can be a tape scrim or a unidirectional tape.

A reinforcement element can be a short-fiber-reinforced or long-fiber-reinforced semi-finished product.

At least one adhesion promoter layer can be provided in order to allow the add-on element to be welded to the wall element allow or to improve the material connection.

According to a further embodiment of the method, it is provided that the add-on element has a functional unit, such as a foil heater, a damping structure or the like. Alternatively, it can be provided that the add-on part consists of a functional unit, such as a foil heater, a damping structure or the like.

In order to provide a device in a simple and cost-effective manner, according to a further embodiment of the method, the lifting device can have a lifting cylinder or a plurality of lifting cylinders, such as a pneumatic cylinder, a hydraulic cylinder or the like. In particular, such a lifting cylinder can have a stop in order to limit the position between the holding position and a pressing position.

Provision can be made for at least one lifting cylinder to be seated in a recess penetrating the contact surface. Provision can also be made for two or more cylinders to be seated in respectively assigned recesses which penetrate the contact surface. Such a recess can, for example, be embedded in a mold surface of a mold half of a blow molding tool, so that the lifting cylinder located in the recess can be compactly fitted into one mold half of a blow molding tool can be integrated.

If a cylinder is seated in a recess formed on a mold half of a blow molding tool, a holding element fastened to the lifting cylinder can be moved into the holding position with the aid of the lifting cylinder. The holding element can thus be fastened to one end of a piston rod of the lifting cylinder and can be moved with the aid of the piston rod into a position which projects into a mold cavity and which corresponds to the holding position.

Alternatively, a recess in a contact surface, in which a lifting cylinder is seated, can be formed on a pressure stamp that is held on a center frame. There can be several lifting cylinders in respectively associated recesses which are embedded in a contact surface and penetrate the contact surface.

According to a further embodiment of the method, it is provided that the wall element is a half-shell for a plastic fuel tank, the wall element being produced in one or more layers by extrusion and blow molding within a blow molding tool. For example, the wall element can have two, three, four, five, six or more layers that are coextruded using an extrusion device.

It can be provided that a heating device, which is provided for heating the add-on element, is a surface heating element.

Provision can be made for a heating device, which is provided for heating the add-on element, to be provided at a distance from a mold, such as a blow mold or the like. Accordingly, while a plastic component is being completed in the blow mold, an add-on element for the production of the plastic component to be produced subsequently can be provided and heated at the same time. After the blow mold has been opened and the plastic component has been removed from the blow mold, a multi-layer wall element intended for blow molding can be coextruded from an extrusion device into a region of the opened blow mold. The add-on element heated with the aid of the external heating device can be fastened and held on a holding device integrated into a mold half before or after the extrusion of the multi-layer wall element.

Another device can then press the wall element against the add-on element, with a surface of a mold half of the blow molding tool forming the contact surface, for example. After the add-on element has been welded to the wall element that is still heated from the previous extrusion process, the blow mold can be closed and blowing pressure can be applied. The wall element is brought into full contact with the tool surface of the mold half of the blow molding tool by the blowing pressure.

According to a second aspect, the invention relates to a device for producing a plastic component, set up for carrying out the method according to the invention, with a device for providing an add-on element, such as a functional unit, a reinforcing element, or the like; with a heating device for heating a connection area of the add-on element; with a holding device for holding a heated add-on element in a holding position, such that the heated add-on element is at a distance from a contact surface in the holding position; with a lifting device which is set up to reduce the distance between the contact surface and the heated add-on element; with a welding device that is set up for welding the heated add-on element to a wall element of the plastic component by pressing the heated add-on element against the wall element, wherein the heated add-on element has a side facing away from the wall element during the welding at least partially rests against the contact surface.

Because the heated add-on element can initially be held at a distance from the contact surface, heat dissipation from the heated add-on element via the contact surface in the holding position can be avoided. In particular, it can be provided that the add-on element has no contact with the contact surface in the holding position.

All the features discussed above with regard to the method, which are also structural features of the device for carrying out the method according to the invention, such as the design of the holding device, the holding elements, the heating device and the like, can also be features of the device according to the invention.

• 1 ein Blasformwerkzeug in einer Seitenansicht;
• 2 eine Vorrichtung zum Herstellen eines Kunststoffbauteils mit dem Blasformwerkzeug aus 1 in einer Schnittdarstellung;
• 3 ein Anbauteil in Halteposition;
• 4 das Anbauteil aus 4 in Andrückposition.

The invention is described in more detail below with reference to a drawing showing exemplary embodiments. They each show schematically:

• 1 a blow mold in a side view;
• 2 a device for producing a plastic component with the blow molding tool 1 in a sectional view;
• 3 an attachment in holding position;
• 4 the attachment off 4 in pressing position.

2 shows a device 2 for producing a plastic component. The device 2 is set up to carry out the method according to the invention.

The device has a blow molding tool 3, only one mold half 5 of the blow molding tool being shown.

The device 2 has a device 4 for providing an add-on element 6. In the present case, the add-on element 6 is an organic sheet 6, which consists of a fiber-reinforced plastic. In the present case, the device 4 for preparing the add-on element 6 is an assembly robot 4.

The device 2 also has a heating device 8 for heating a connection area 10 of the add-on element 6. In the present case, the heating device 8 is an infrared radiator 8 designed as a surface heating element.

The device 2 has a holding device 12 for holding the heated add-on element 6 in a holding position such that the heated add-on element 6 is at a distance a from a contact surface 14 in the holding position.

In the present case, the holding device 12 is at the same time a lifting device 12 which is set up to reduce the distance a between the contact surface 14 and the heated add-on element 6 .

The device 2 also has a welding device 16, which is set up for welding the heated add-on element 6 to a wall element 18 of the plastic component by pressing the heated add-on element 6 against the wall element 18, with the heated add-on element 6 being welded to a side facing away from the wall element 18 20 rests against the contact surface 14. The welding device 16 is therefore a mechanical pressing device 16 in the present case.

The distance a is 30 mm in the present case.

In the present case, the holding device 12 has three holding elements 22 , 24 , 26 which hold the heated attachment 6 in the holding position after the heated attachment has been transferred to the holding device 12 by the assembly robot 4 .

In the present case, each of the three holding elements 22, 24, 26 is a vacuum suction cup 22, 24, 26. The structure of the vacuum suction cups 22, 24, 26 is described below using the vacuum suction cup 24 as an example.

The vacuum cup 24 has a rigid suction surface 28 formed on an insert 30, the insert 30 being made of a porous sintered material. The insert 30 is exchangeably held on a piston element 32 . A sealing ring 34 is used to seal off the suction surface 28 from an environment U, insofar as the attachment 6 is held on the holding device 12 .

The piston element 32 and the piston rod 36 are hollow and connected to a vacuum pump 38 .

The piston rod 36 is part of a lifting cylinder 40, through which the holding element 24 from the holding position ( 3 ) into a pressing position (cf. 4 ) is movable. In the pressing position, the distance a is equal to 0.

As 2 As can be seen, the cylinder 40 sits with its piston rod 36 and the piston element 32 in a recess 42 penetrating the contact surface 14 in the mold half 5 of the blow molding tool 3.

To produce a plastic component, the organic sheet 6 is first provided with the aid of the assembly robot 4 and heated with the aid of the heating device 8 so that the connection area 10 is in an at least partially plasticized or melted state ( 1 ).

The blow molding tool 3 is in the open state.

The heated organic sheet 6 is rotated and then transferred to the holding device 12 with the aid of the assembly robot 4 and/or another device connected in between, so that the organic sheet 6 rests with the side 20 on the vacuum suction cups 22, 24, 26 and is held in place by the vacuum suction cups 22, 24, 26 is held in the holding position, in which the vacuum pump 38 generates a negative pressure ( 3 ).

Before or after the organic sheet 6 is transferred to the holding device 12, a wall element 18 is coextruded, which in the present case has a five-layer wall structure.

The wall element 18 is pressed against the heated organic sheet 6 with the aid of the mechanical pressing device 16 in order to cause the organic sheet 6 to be welded to the wall element 18 . During the welding process, the wall element 18 is still in the at least partially plasticized or melted state due to the remaining heat from the extrusion process.

Before the wall element 18 is welded to the organic sheet 6, the organic sheet 6 is transferred from the holding position to the pressing position, in which the distance a is equal to 0. A contact time during which the heated organic sheet is in contact with the contact surface 14 before it comes into contact with the wall element 18 is less than 1 second in the present case.

In the present case, the organic sheet 6 is welded to an outside 44 of the wall element 18 facing the forming tool 3 .

In the present case, the contact surface 14 is the tool surface 14 of the mold half 5 of the blow molding tool 3.

Reference List

2

contraption

3

blow molding tool

4

Device for providing an add-on element

5

mold half

6

add-on element

8th

heating device

10

connection area

12

holding device/lifting device

14

contact surface

16

Welding device/pressing device

18

wall element

20

opposite side

22

holding element

24

holding element

26

holding element

28

suction surface

30

mission

32

piston element

34

sealing ring

36

piston rod

38

vacuum pump

40

lifting cylinder

42

recess/through opening

44

Outside of the wall element 18

a

Distance

u

vicinity

Claims (16)

Method for producing a plastic component, with the method steps: - Providing an add-on element (6), such as a functional unit, a reinforcing element; - Heating a connection area (10) of the add-on element (6); - Holding the heated add-on element (6) in a holding position, wherein the heated add-on element (6) in the holding position has a distance (a) to a contact surface (14); - Reducing the distance (a) between the contact surface (14) and the heated add-on element (6) using a lifting device (12); - Welding the heated add-on element (6) to a wall element (18) of the plastic component by pressing the heated add-on element (6) against the wall element (18), the heated add-on element (6) being on a side facing away from the wall element (18) during the welding (20) rests against the contact surface (14) at least in sections. procedure after claim 1 , characterized in that the heated add-on element (6) is pressed against the wall element by means of a mechanical pressing device (16) or vice versa in order to cause the add-on element (6) to be welded to the wall element (18). Procedure according to one of Claims 1 or 2 , characterized in that - the distance (a) of the add-on element (6) from the contact surface (14) in the holding position is 50 mm or less, and/or - the distance (a) of the add-on element (6) from the contact surface (14 ) in the holding position is 5 mm or more. Procedure according to one of Claims 1 until 3 , characterized in that - a contact period during which the heated add-on element (6) bears against the contact surface (14) prior to contact with the wall element (18) is five seconds or less; or - a contact period during which the heated add-on element (6) bears against the contact surface (14) before contact with the wall element (18) is 2 seconds or less; or - a contact period during which the heated add-on element (6) is in contact with the contact surface (14) before it comes into contact with the wall element (18) is one second or less. Method according to any of the foregoing Claims 1 until 4 , characterized in that - the add-on element (6) is welded to an outer side (44) of the wall element (18) facing a shaping tool (5), a tool surface (14) for shaping the wall element (18) forming the contact surface (14). or - the add-on element (6) is welded to an inside of the wall element (18) facing away from a forming tool (5), with a surface of a pressure stamp forming the contact surface, which is held on a central frame. Method according to any of the foregoing Claims 1 until 5 , characterized in that two or more add-on elements (6) are welded to the wall element (18). procedure after claim 5 and claim 6 , characterized in that at least one add-on element (6) is welded to the inside of the wall element (18) and at least one further add-on element is welded to the outside of the wall element (18). Method according to any of the foregoing Claims 1 until 7 characterized in that - the heated add-on element (6) is held in a holding position with the aid of a holding device (12) which fixes the heated add-on part with at least one holding element (22, 24, 26) or a plurality of holding elements (22, 24, 26) in the holding position, - wherein a contact surface of the holding device (12) to the heated add-on element (6) is less than 10% of a surface of the connection area (10) to be welded. Procedure according to one of Claims 1 until 8th , characterized in that - the holding device (12) has at least one holding element (22, 24, 26) which, starting from the holding position, can be moved into a pressing position, - the holding element (22, 24, 26) in the pressing position being flush with the Contact surface (14) is arranged or is arranged set back relative to the contact surface (14). procedure after claim 8 or claim 9 , characterized in that - at least one holding element (22, 24, 26) is a vacuum suction cup (22, 24, 26) which has a rigid suction surface for holding the add-on element; and/or - at least one holding element is a needle or a mandrel; and/or - at least one holding element is a gripper. Procedure according to one of Claims 1 until 10 characterized in that - the add-on element (6) has a reinforcing element (6), such as an organic sheet, a fiber-reinforced tape, or - the add-on element (6) consists of a reinforcing element (6), such as an organic sheet or a fiber-reinforced tape. Method according to any of the foregoing Claims 1 until 11 , characterized in that - the add-on element has a functional unit, such as a foil heater, a damping structure, or - the attachment consists of a functional unit, such as a foil heater, a damping structure. Method according to any of the foregoing Claims 1 until 12 , characterized in that the lifting device (12) has a lifting cylinder (40) or a plurality of lifting cylinders (40), such as a pneumatic cylinder, a hydraulic cylinder. procedure after Claim 13 , characterized in that at least one lifting cylinder (40) sits in a recess (42) penetrating the contact surface (14). Method according to any of the foregoing Claims 1 until 14 , characterized in that - the wall element (18) is a half-shell for a plastic fuel tank, - the wall element (18) being produced in one layer or in multiple layers by extrusion and blow molding within a blow molding tool. Device for producing a plastic component - Set up to carry out the method according to one of Claims 1 until 15 - With a device (4) for providing an add-on element (6), such as a functional unit, a reinforcing element; - With a heating device (8) for heating a connection region (10) of the add-on element (6); - With a holding device (12) for holding a heated add-on element in a holding position, such that the heated add-on element (6) in the holding position has a distance (a) to a contact surface (14); - With a lifting device (12) which is set up to reduce the distance (a) between the contact surface (14) and the heated add-on element (6); - with a welding device (16), which is set up for welding the heated add-on element (6) to a wall element (18) of the plastic component by pressing the heated add-on element (6) against the wall element (18), the heated add-on element (6) during of the welding with a side (20) facing away from the wall element (18) rests at least in sections on the contact surface (14).

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