Method for joining a metal component and a polymer component and a structure comprising said components

Background of the invention

The invention relates generally to j oining of components of different materials , and especially to j ointing metal components and polymer components together .

Thereby, a structure and a method implementing such j oining technique are disclosed .

The obj ect of the invention is described in more detail in the preambles of independent claims of the application .

There is a continuously growing need for lightweight design in several industries , mainly in the field of transportation . This need has led to the usage of alternative lighter materials and new solutions . New obstacles arise in search of more lean and efficient designs . One of these obstacles is the need to j oin different types of engineering materials via dissimilar material j oining ( DMJ) methods . Achieving satisfactory physical and chemical performance is difficult in DMJ due to fundamental differences in the physical and chemical properties of the base components . It has been especially challenging for making j oints between metallic and polymeric components . Some techniques and arrangement have been developed for this purpose . However, it has been found that there are drawbacks in the current solutions which limits their usage for industrial scale production .

Brief description of the invention

The idea of the invention is to provide a new and improved concept to j oin metal to polymer .

The characteristic features of the structure according to the invention are presented in the characteri zing part of the first independent claim . The characteristic features of the method according to the invention are presented in the characteri zing part of the second independent claim .

In this document the metal-polymer j oining is based on j oining technique called a Through Slot Extrusion Joining with acronym TSEJ . This acronym TSEJ is used in this document for simplicity reasons and for improving clarity .

TSEJ is a method to produce continuous j oints between a metallic component and a polymeric-based component in an overlap- j oint configuration . The TSEJ method uses a rigid extrus ion die system which forms a continuous linear or non-linear slot through which the metallic component will be forced, or extruded, into the polymeric-based component . The continuous linear or non-linear slot is the aperture , or slit , formed by the inner edges of the rigid extrusion die system . The metallic component is forced by a rigid rotating tool , with a tool probe and a tool shoulder, into the polymeric-based component , through the continuous linear or non-linear slot of the rigid extrusion die system, when this rigid rotating tool is plunged in the metallic component and travels along the same path of the continuous linear or non-linear slot . The portion of the metallic component being mechanically processed by the rigid rotating tool softens as result of the heat energy release during the bulk plastic deformation . Thi s heated and softened portion of the metallic component is then forced through the continuous linear or non-linear slot of the rigid extrusion die system into the polymer-based component . During the processing phase of the TSEJ j oint, the tool shoulder keeps the top surface of the metallic component closed, and the tool probe produces the bulk plastic deformation of the metallic component . As the metallic component is forced into the polymeric-based component , the local interaction between these components results in that the constrained polymeric-based component , reacts by forcing its way into the metallic component , forming a geometrical complex shape in the forced, or extruded, portion of the metallic component resulting in the formation of a hook or crab claws shape . This hook or crab claws shape which is now filled with the polymeric-based component forms a strong mechanical interference , also known as clinching . The j oining mechanisms of TSEJ result from this strong mechanical interference , with the additional contribution of the physical and chemical adhesive and diffusion phenomena at the contacting interface between the metallic component and the polymeric-based component .

The idea of the proposed solution is to provide a structure wherein the mentioned continuous TSEJ j oint is implemented in a structure compri sing a T-j oint between the metallic component and the polymer-based component . An edge of the polymer-based component is in the T-j oint arranged perpendicularly against a planar surface of the metallic component . The TSEJ j oining technique forms hooks of the metallic component and the hooks are penetrated in the structure inside the polymer-bases component .

An advantage of the disclosed solution i s that the disclosed T-j oint has excellent mechanical strength properties and it can be implemented in a versatile manner in different structural pieces , elements , and components .

The structure comprises one or more metallic components , one or more polymer-based components , and at least one continuous j oint between them . The structure further comprises at least one T-j oint wherein the metallic component and the polymer-based component are orientated perpendicularly relative to each other . Further, cross-section of the continuous j oint is located at the T-j oint and comprises hook configuration made of the metallic component and extruded into the polymer-based component .

According to an embodiment , the metal lic component is of lightweight metallic material .

According to an embodiment , the metall ic component is of aluminium or aluminium alloy material . According to an embodiment , the metall ic component is of magnesium or magnesium alloy material .

According to an embodiment , the polymer-based material may be for example polyether ether ketone PEEK, carbon fiber reinforced polymer CFRP, glas s fiber reinforced polymer, or thermoplastic structural polymer .

According to an embodiment , at least one edge surface of the at least one polymer-based component is fastened by means of metallic hooks or claws to a planar surface of the at least one plate-like metallic component .

According to an embodiment , the structure has onesided configuration with one metal lic component and one or more transverse polymer-based components . Then there is one or more T-j oints only on one side of the structure .

According to an embodiment , the structure has two- sided configuration with two spaced metallic components and one or more transverse polymer-based components . Then there are one or more T-j oints on two oppos ite sides of the structure .

According to an embodiment , the continuous j oint at the T-j oint has a linear configuration .

According to an embodiment , the continuous j oint at the T-j oint has a non-linear configuration .

According to an embodiment , the polymer-based component comprises a waved contact surface facing towards a planar mating surface of the metallic component .

According to an embodiment , the structure comprises at least two T-j oints at a distance from each other .

According to an embodiment , the structure comprises at least two T-j oints on opposite sides of the polymer- based component .

According to an embodiment , the structure further comprises : two metallic components at a distance from each other and serving as flanges in the structure ; and at least one polymer-based component fastened by means of the T- j oints between the mentioned flanges and serving as a web in the structure .

According to an embodiment , the structure comprises several polymer-based and spaced webs . The spaced webs may be parallel or non-parallel .

According to an embodiment , the structure comprises only one web and is a beam .

According to an embodiment , the structure has I - shaped cross-section, whereby the structure is an I -beam . In the I -beam structure width of the web may be greater than width of the flanges .

According to an embodiment , the structure has H- shaped cross-section, whereby the structure is a H-beam . In the H-beam structure width of the flanges may be greater than width of the web between the flanges .

According to an embodiment , the structure comprises two polymeric-based webs at a transverse distance from each other .

According to an embodiment , the structure comprises three , four, five , or more polymeric-based webs at a transverse distance from each other .

According to an embodiment , the structure has a boxlike configuration . The box may be closed or open .

According to an embodiment , the structure has a boxlike configuration with a closed shape and comprises a top panel , a bottom panel , and a side panel between the top panel and the bottom panel . The top panel and the bottom panel both comprise the metallic components . The side panel comprises at least one polymer-based component . Further, the top panel and the bottom panel are j oined to the side panel by means of the T-j oints .

According to an embodiment , the structure has a boxlike configuration with an open shape and comprises a top panel , a bottom panel , and a side panel between the top panel and the bottom panel . The top panel and the bottom panel both comprise the metallic components . The side panel comprises at least one polymer-based component and has at least one side opening. Further, the top panel and the bottom panel are joined to the side panel by means of the T- oints .

According to an embodiment, the structure has a boxlike configuration with an open shape and comprises one of the following panels formed of the metallic components: a top panel, a bottom panel. The panel formed of the metallic component is joined to a side panel formed of the polymer- based component by means of the T-joint.

According to an embodiment, the structure has a boxlike configuration with rectangular shape.

According to an embodiment, the structure has a boxlike configuration with circular, oval or curved shape. Then the side panel or web may have waved, tubular or rounded form.

According to an embodiment, providing the structure with at least one T-joint wherein the continuous joint has a closed joint geometry. The T-joint may surround a top panel or bottom panel of a box-like structure for example.

According to an embodiment, the continuous joint at the T-joint is a load bearing structural joint. An advantage is that the joint is capable of bearing mechanical stresses.

According to an embodiment, the closed joint geometry formed by the continuous joint is a fluid pressure tight joint. The closed joint may be gas and liquid tight. This feature is advantageous for example when forming boxlike structures or cover elements.

According to an embodiment, the structure comprises an extrusion die plate structure between the metallic component and the polymer-based component. Further, the extrusion die plate structure comprises a slot with a path corresponding to the path of the continuous joint.

According to an embodiment, the structure comprises an extrusion die plate structure or extrusion die system during the j oining process but is removed from the final structure after the j oint in finished .

According to an embodiment , the disclosed solution relates also to a method for j oining one or more metallic components and one or more polymer-based components together by means of one or more j oints . The method comprises : placing a metallic component and a polymeric-based component towards each other at a j oint area ; providing the j oint area with an extrusion die plate structure comprising a through opening; rotating and plunging a probe of a non-consumable tool across the thickness of the metallic component ; and extruding part of the metallic component through the opening of the extrusion die plate structure into the polymer-based component for forming hooks protruding into the polymeric- based component and forming a j oint between the metallic component and the polymer-based component . The method further comprises : placing the polymeric-based component transversally in relation to the metallic component and forming thereby a T-shaped configuration at the j oint area ; and implementing an extrusion die plate structure compris ing a slot and providing the j oint with a continuous j oint path along the j oint whereby the j oint area comprises at least one T-j oint for the T-shaped configuration of the metallic component and the polymer-based component .

According to an embodiment , the method further comprises : arranging at least one polymer-based component between two metallic components ; orientating the polymer- based component transversally in relation to planar surfaces of the two metallic components ; and j oining the two metal lic components to opposing edge surfaces of the polymer-based component by means of the T-j oints .

According to an embodiment , the metal lic component and the polymer-based component may be orientated perpendicular in relation to each other .

According to an alternative embodiment , the metallic component and the polymer-based component may be angled in relation to each other. The angle may be 20 - 160°, typically 30°, 45° or 60°, or 120°, 135° or 150°, for example .

According to an embodiment, the disclosed solution:

- processes bulk materials into novel structures;

- does not coat a surface with processed powdered material ;

- does not rely on adaptor components and materials between the metallic component and polymer-based component to be joined, rather, it joins the components directly;

- utilizes no interfacial adhesives by necessity or intent ;

- uses no fasteners to create a joint;

- joins metal to polymer as a primary joint, with the polymer capable of constituting a structural member;

- the joints are created with a combination of mechanical interlocking, adhesive bonding, and diffusion mechanisms;

- is capable of long, continuous joints.

The above-presented embodiments and the features they contain may be combined to provide desired configurations .

Brief description of the figures

Some embodiments of the proposed solution are illustrated more specifically in the following figures, in which,

Figure 1 shows schematically steps of using through- slot extrusion joining TSEJ in manufacture of a multi-material structural system with T-joint design,

Figure 2 comprises subfigures 2a - 2e and shows schematically a structure with a T-joint design implementing single-side TSEJ joining process along a linear path, Figure 3 shows schematically some dif ferent crosssections of hook-type j oints formed by means of the TSEJ process for T-j oints ,

Figure 4 comprises subfigures 4a - 4c and shows schematically use of the TSEJ process for producing a T- j oint between a planar metallic component and a wavy polymer-based component ,

Figure 5 comprises subfigures 5a and 5b and shows schematically use of the TSEJ j oining technique for producing a beam-like single-web structure with a double sided T- j oint design,

Figure 6 comprises subfigures 6a - 6d and shows schematically a beam-like s ingle-web structure with a wavy polymer-based web fastened between two metallic flanges ,

Figure 7 comprises subfigures 7a - 7c and shows schematically a double-web structure with two polymeric- based webs fastened between two metallic flanges ,

Figure 8 comprises subfigures 8a - 8c and shows schematically a triple-web structure with three polymeric- based webs fastened between two metallic flanges ,

Figure 9 comprises subfigures 9a - 9c and shows schematically an open box-shaped structure in Figure 9b and its production in Figures 9a and 9c,

Figure 10 comprises subfigures 10 a - 10 c and shows schematically a closed box-shaped structure in different angles of view,

Figure 11 comprises subfigures I l a - 11 c and shows schematically an alternative open box-shaped structure ,

Figure 12 comprises subfigures 12 a - 12 c and shows in Figure 12a picture of a cross-section of a T-j oint and Figures lb and 12c are pictures showing top and bottom views of the same .

For clarity purposes , some embodiments of the proposed solutions are illustrated in a simplified form in the figures . The same reference numbers are used in the figures to denote the same elements and features . Detailed description of some embodiments

Figure 1 discloses a sequence via through-slot extrusion joining (TSEJ) of manufacturing of a multi-material structural system with T-joint design, in single-side, along a linear path: Step i) the exploded perspective of the components; Step ii) the tool (5) is positioned above a pre hole (8) and the multi-component extrusion die (3) is closed to form the extrusion slot (4) ; Step iii) the start position of the manufacturing system, with the components clamped and the tool (5) ready to travel with rotation implement the joining process on the T-joint design; Step iv) the perspective upon extraction of the tool (5) but before extraction of the multicomponent extrusion die; Step v) the perspective upon extraction of the multicomponent extrusion die (3) .

Figure 2 discloses a perspective on the T-joint design, in single-side, along a linear path, with an exemplary embodiment of a joint cross-sectional structure depicting in Detail a, the extruded metallic plate (1) into the shape of a hook or crab (6) acting as a joining mechanism for the T-joint design. At the top with the multicomponent extrusion die (3) and at the bottom, without the multicomponent extrusion die (3) .

Figure 3 discloses exemplary embodiments of structures formed with TSEJ. The crab claw-like structure can develop asymmetrically (A) ; with long and thin structures (B) ; short and thick (C) ; or short and symmetric rounded claws (D) . The tool geometry (5a, 5b) determines the form of these structures.

Figure 4 discloses implementation of the T-joint design, in single-side, along a non-linear waved joining path ( 7 ) .

Figure 5 discloses simultaneous implementation in double side, with one flange, of the T-joint design along a linear joining path (7) . This results in a I- or H- shape beam with the two flanges made of lightweight metallic material and the web made of polymer-based material.

Figure 6 discloses simultaneous implementation in double-side, with one flange, of the T-joint design along a non-linear joining path (7) . This results in a I- or H- shape beam with the two flanges made of lightweight metallic material and the web made of polymer-based material.

Figure 7 discloses implementation in double-side, with two-spaced webs, of the T-joint design along a linear joining path (7) . This results in two flanges made of lightweight metallic material and a double-web made of polymer- based material.

Figure 8 discloses implementation in double-side, with three-spaced webs, of the T-joint design along a linear joining path (7) . This results in two flanges made of lightweight metallic material and a triple-web made of polymer- based material.

Figure 9 discloses implementation in an open boxshaped flange structural system, with the T-joint design applied in single-side along a square non-linear joining path (7) . This results in an open box-shape structural system with one end flanges made of lightweight metallic material and the box-shape web made of polymer-based material.

Figure 10 discloses implementation in a closed boxshaped flange structural system, with the T-joint design applied in double-side along a square non-linear joining path (7) . This results in a closed box-shape structural system with two end flanges made of lightweight metallic material and the box-shape web made of polymer-based material .

Figure 11 discloses implementation in an open boxshaped flanged structural system, with the T-joint design applied in double-side along a square non-linear joining path (7) . This results in an open box-shape structural sys- tem with two end flanges made of lightweight metallic material and the open box-shape web made of polymer-based material .

Figure 12 discloses a real-world T-joint design made between a metallic component (1) and a polymer based component (2) with a removable extrusion die system (3) . The top image is a cross-section with the extruded hook/crab joining mechanism (6) , and the lower images are the top and bottom side of the finished component.

TSEJ is a method to produce continuous joints between a metallic component (1) and a polymer-based component (2) in an overlap- j oint configuration. The TSEJ method uses a rigid extrusion die system (3) which forms a continuous slot (4) through which the metallic component (1) will be forced, or extruded, into the polymer-based component (2) . The continuous slot (4) is the aperture, or slit, formed by the inner edges of the rigid extrusion die system (3) . The metallic component (1) is forced by a rigid rotating tool (5) , with a tool probe (5a) and a tool shoulder (5b) , into the polymer-based component (2) , through the continuous slot (4) of the rigid extrusion die system (3) , when this rigid rotating tool (5) is plunged in the metallic component (1) and travels along the same path of the continuous slot (4) . The portion of the metallic component (1) being mechanically processed by the rigid rotating tool (5) softens as result of the heat energy release during the bulk plastic deformation. This heated and softened portion of the metallic component (1) is then forced through the continuous slot (4) of the rigid extrusion die system (3) into the polymer- based component (2) . During the processing phase of the TSEJ joint (7) , the tool shoulder (5b) keeps the top surface of the metallic component (1) closed, and the tool probe (5a) produces the bulk plastic deformation of the metallic component (1) . As the metallic component (1) is forced into the polymer-based component (2) , the local interaction between these components results in that the constrained polymer-based component (2) , reacts by forcing its way into the metallic component (1) , forming a geometrical complex shape in the forced, or extruded, portion of the metallic component (1) resulting in the formation of a hook or crab claws shape (6) . The process evolutes in a quasi-conserva- tion of volume, so no significant voids are formed in the joining zone. The hook or crab claws shape (6) which is filled with the polymer-based component (2) forms a strong mechanical interference, also known as clinching. The joining mechanisms of TSEJ result from this strong mechanical interference, with the additional contribution of the physical and chemical adhesive and diffusion phenomena at the contacting interface between the metallic component (1) and the polymer-based component (2) .

The TSEJ cycle develops along the following sequence :

-The metallic component (1) , the polymer-based component (2) with the rigid extrusion die system (3) in between, are brought together and clamped in overlap- j oint, or T-joint configuration;

-To prevent the formation of flash, during the initial plunge of the tool probe (5a) of the rigid rotating tool (5) , a pre-hole (8) may be opened in the metallic component (1) at the start position of the TSEJ joint (7) . This pre-hole (8) can be cylindrical or conical. This prehole (8) can be blind or through. This pre-hole (8) can be larger, smaller, or equal to the diameter of the tool probe (5a) ;

-The tool probe (5a) of the rigid rotating tool (5) , is plunged at the start position of the TSEJ joint (7) until the tool shoulder (5b) contacts the top surface of the metallic component (1) ; -Upon a given dwell time, that can be equal to zero seconds or more, the rigid rotating tool (5) travels along the path of the continuous slot (4) , with constant or variable travel speed;

-At the end position of the TSEJ joint (7) , the rigid rotating tool (5) is extracted from the metallic component ( 1 ) ;

-The consolidated TSEJ joint (7) and inherent structural system is extracted from the clamping.

The hook or crab claws shape (6) formed by the metallic component (1) in interaction with the polymer-based component (2) can have the following configurations:

-Configuration of a hook, where only one of the sides of the extruded portion of the metallic component (1) extends into the polymer-based component (2) ;

-Configuration of a symmetrical crab claw, where both sides of the extruded portion of the metallic component (1) extends equally into the polymer-based component (2) ;

-Configuration of an asymmetrical crab claw, where both sides of the extruded portion of the metallic component

(1) extends differently into the polymer-based component

(2) .

The width of the continuous slot (4) is greater than zero, and it can be constant or variable. The continuous slot (4) can follow a one-dimensional, two-dimensional, or three-dimensional path.

The rigid extrusion die system (3) can be made of one (e.g., monolithic die (3a) ) , or more components (e.g. strips (3b) ) , which define an inner continuous slot (4) . After the TSEJ cycle is completed, if the rigid extrusion die system (3) if made of multiple components, it may be kept, within the joint, or it may be extracted.

The rigid extrusion die system (3) can be fully, or partially, embedded in the metallic component (1) , or in the polymer-based component (2) , or partially embedded in both the metallic component (1) and the polymer-based component (2 ) .

The surface of the polymer-based component (2) , facing the joining domain, can be flat, or have one or more shallow grooves, to mate with the fully, or partially embedded rigid extrusion die system (3) .

The surface of the metallic component (1) , facing the joining domain, can be flat, or have one or more shallow grooves, to mate with the fully, or partially embedded rigid extrusion die system (3) .

The rigid extrusion die system (3) is made of high- strength material compared with the strength of the metallic component (1) and the polymer-based component (2) . The rigid extrusion die system (3) is made with minimum thickness, as long as it provides rigidity effect to act as rigid, i.e. non-def ormable, extrusion die.

The joint configuration between the overlapping metallic component (1) and the polymer-based component (2) forms a T-joint design. The rigid extrusion die system (3) is positioned parallel, under and in contact with the metallic component (1) , while the polymer-based component (2) is positioned perpendicular to the metallic component (1) .

In TSEJ, the TSEJ joint (7) length is longer than zero, with no maximum length. A TSEJ joint (7) can include zones of overlap and/or intersection with previous TSEJ joint (7) processed zones.

The rigid rotating tool (5) can be made in one single component or made of multicomponent assembled together, namely a tool probe (5a) and a tool shoulder (5b) .

T-joint design with a linear joint enables to get a T-shape structural beam, i.e., a load-bearing system, with the one flange made of lightweight metallic material and the one web made of polymer-based material.

The web can be planar, joining the multilateral components with a linear T-joint design. The web can be non-planar (e.g., waved) joining the multilateral components with a non-linear T-joint design.

T-joint design enables to get a I- or H-shape structural beam, i.e., a load-bearing system, with two flanges made of lightweight metallic material and one web made of polymer-based material with a shape that can be planar or non-planar, e.g., a waved shape.

T-joint design enables to get a multi-web-shape structural beams, i.e., a load-bearing system, with the two flanges made of lightweight metallic material and two, or more, webs made of polymer-based material, with a shape that can be planar or non-planar, e.g., a waved shape.

The TSEJ manufacturing of the T-joint design in I- shape, H-shape, and multi-web-shape structural beams can be made in sequence or simultaneously.

The TSEJ manufacturing of the T-joint design enables other complex-shape structural beams such as closed and open box-shaped flanged structural system, with the T-joint design applied in single or double-side along non-linear joining path (7) . In these structures, the end flange (s) are made of lightweight metallic material and the open or closed box-shape web made of polymer-based material.

The length of the tool probe (5a) and the plunged position of the rigid rotating tool (5) during the manufacturing of the TSEJ joint (7) , is such that the tip of the tool probe (5a) can be positioned above, below, or at the level of the rigid extrusion die system (3) .

The parameters controlling the process TSEJ are the following :

1. Geometry of the tool probe (5a) ;

2. Geometry of the tool shoulder (5b) ;

3. Rotation speed of the tool (5) , or of the probe (5a) , if the shoulder (5b) is static;

4. Plunging speed or plunging force of the tool (5) ;

5. Plunging depth of the tool (5) ; 6. Dwell time at the maximum plunge depth, in plunging force or vertical position control;

7. Extraction speed of the tool (5) ;

8. Travel speed of the tool (5) , if the probe (5a) is continuous plunged in the metal component (1) , traversing along the path of the slot (4) in the extrusion die system (3) ;

9. Offset distance between the central axis of the tool (5) and the center of the slot (4) ;

10. Material and thickness of the extrusion die system (3) ;

11. Dimensions (including thickness) and form of the extrusion die system (3) ;

12. Width of slot (4) of the extrusion die system (3) ;

13. Path and orientation of the slot (4) of the extrusion die (3) ;

14. Material and thickness of the metal component (1) ;

15. Material and thickness of the polymer-based component (2 ) .

List of reference numerals:

1. Metallic component

2. Polymer-based component

2a. Shallow groove (optional) in polymer component (2) , to mate with the extrusion die system (3)

3. Rigid extrusion die system (thin and rigid plate compared with the metal (1) and the polymer (2) , at processing thermomechanical conditions)

3a. Monolithic, or single component extrusion die system (3) 3b. Multi-body extrusion die system (3) consisting of multiple components to constitute the system

4. Slot, or aperture, formed by the extrusion die system (3)

5. Non-consumable and rigid joining tool

5a. Probe of the non-consumable and rigid welding tool (5)

5b. Shoulder of the non-consumable and rigid welding tool (5)

6. Hook or crab claw shape formed by the extruded portion of the metallic component into the polymer-based component when viewed on a cross section parallel to the processing path

7. TSE J j oint

8. Blind- or through-hole style pre-hole used at (or in the vicinity of) the plunge location

9. Metal-polymer-metal stack with doubleside TSEJ joint

10. Exit hole, where the tool exits

11. Joint start

12. Joint end

13. T-joint

14. Flange, formed of metallic component

15. Web, formed of polymer-based component

16. Edge side of polymer-based component

17. Planar surface of metallic component

18. One-sided structure

19. Double-sided structure

20. Box-like structure, closed

21. Box-like structure, open

22. Panel

23. Side panel

24. Top panel 25 . Bottom panel

26 . Opening, top or bottom panel missing, or side opening The figures and their description are only intended to illustrate the inventive idea . However, the scope of protection of the invention is defined in the claims of the application .