EP2245321A1

EP2245321A1 - Method for fastening a component and fastener for carrying out the method

Info

Publication number: EP2245321A1
Application number: EP09713902A
Authority: EP
Inventors: Reinhold Opper; Michael Krengel; Jochen Hain
Original assignee: Newfrey LLC
Current assignee: Newfrey LLC
Priority date: 2008-02-27
Filing date: 2009-02-26
Publication date: 2010-11-03
Also published as: JP2011514491A; DE102008011344A1; WO2009108787A1

Abstract

In the method, at least one component (14) is fastened to a base component (12) with the aid of a fastener (1) that has a sleeve (2) with a fastening end and, located within the sleeve, a mandrel by means of which the sleeve (2) can be plastically deformed to increase its diameter, wherein the fastener (1) is fastened by its fastening end to the base component (12), the component (14) is aligned in a predetermined position relative to the base component (12) and the fastener (1), wherein the fastener (1) projects through an opening (15) in the component (14), the diameter of the sleeve (2) is enlarged in a region between the component (14) and the base component (12) with the aid of the mandrel, and a seat (18) is formed on the underside (17) of the component (14), and an opposing head (20) is swaged onto the top (19) of the component (14), and subsequently the mandrel is at least partially removed.

Description

METHOD FOR FASTENING A COMPONENT AND FASTENER FOR CARRYING OUT THE METHOD

Cross-Reference To Related Applications

[0001] This application claims priority from German Patent Application No. 10 2008 011 344.1 , filed on February 27, 2008, the disclosure of which is incorporated herein by reference. Technical Field

[0002] The invention concerns a method for fastening at least one component to a base component with the aid of a fastener extending through an opening in the component, wherein the fastener is fastened by a fastening end to the base part and is subsequently plastically deformed. The invention also relates to a fastener for carrying out the aforementioned process. Background Art

[0003] A method of the aforementioned type is known from DE 10 2005 006,253 B4. In this prior art method, a T-shaped stud is inserted through a hole in the component to be fastened, and is then electrically welded at its end face to the surface of the base component. Thereafter, the shank of the stud, which has a head at its free end, is heated by a second electrical impulse generated after the end face is welded on, and is simultaneously swaged until the underside of the head contacts the surface of the component. In this process, the shank of the stud can be swaged to such a degree that it completely fills the hole in the component in the circumferential direction in some areas. This prior art method is suited only to applications in which the component can be firmly pressed against the base component during joining. Moreover, it has the disadvantage that the component must be arranged on the base component before the stud is welded, and the welding of the stud takes place in the presence of both components. This severely restricts the welding method and also the choice of material for the component. It is also disadvantageous that the base component is stressed by the force necessary to swage the stud, and under some circumstances must be additionally supported on the side facing away from the joint side.

[0004] The joining of components frequently involves the problem that dimensional variations resulting from manufacturing tolerances arise at the joint locations. Especially in the joining of sheet metal parts in automobile manufacture, it can occur that dimensional variations at the joint locations resulting from manufacturing tolerances must be compensated for in order to prevent the components or assemblies that are to be joined from being distorted or buckled when joined. In order to compensate for such dimensional variations during joining, compensating threaded joints for are known, for example from DE 10 84 766 T5; they generally consist of three or four separate elements, are expensive, and are complicated to install. Disclosure of Invention

[0005] The object of the invention is to specify a method of the initially mentioned type that is suitable for compensating dimensional variations between the component and the base component and permitting stress-free joining of the components. Moreover, the method must be simple and economical to carry out. The invention has the further object of creating a fastener that is suitable for carrying out the method, and that is simple and economical to manufacture. [0006] According to the invention, the specified object is attained by a method in which at least one component is fastened to a base component with the aid of a fastener that has a sleeve with a fastening end and, located within the sleeve, a mandrel by means of which the sleeve can be plastically deformed to increase its diameter, wherein the fastener is fastened by its fastening end to the base component, the component is aligned in a predetermined position relative to the base component and the fastener, wherein the fastener projects through an opening in the component, the diameter of the sleeve is enlarged with the aid of the mandrel in a region surrounded by the component, and an adhesion, in particular surface contact with the inside of the hole, is produced between the sleeve and the component, and the mandrel is subsequently at least partially removed. Preferably, a seat is formed on the underside of the component by the enlargement of the sleeve, and an opposing head is swaged onto the top of the component.

[0007] As a result of the inventive method, it is possible to join a component to a base component in an area that extends from zero separation between the components to a separation determined by the length of the sleeve. In this way, the component can be joined to the base component at the existing tolerance position that results from manufacture without causing distortion or buckling of the component. Once the fastener is fastened to the base component, the establishment of the joint between the fastener and the component takes place by the application of a tensile force to the mandrel with the aid of a conventional tool known for setting blind rivets, wherein the opposing force is supported at the free end of the sleeve with the aid of the tool. Thus, no significant external forces arise that stress the base component or component. Once the seat is formed at the bottom of the component and an opposing head is swaged onto the top of the component, increased tensile force is used to tear the portion of the mandrel projecting from the opposing head away from the head that produces the deformation and remove it, in a manner similar to that used for blind rivets. The two components are now fixed together by at least a frictional engagement, e.g. by surface contact with the inside of the hole, or by an interlocking engagement, in the position in which they were previously placed relative to one another in a stress-free manner. Alternatively, the mandrel can also be pulled completely out of the deformed sleeve.

[0008] The fastening end of the fastener can be fastened to the base component in a variety of ways, for example by welding, soldering, gluing, or else mechanically, for example by being screwed on. However, a preferred fastening type is drawn arc welding, which has been proven in automobile manufacture in particular and ensures a connection between the base component and sleeve that is stable and quick to produce. Since an annular ring can form at the fastening end of the fastener during welding or soldering, in accordance with another proposal of the invention the underside of the component can be provided with a recess surrounding the opening that can accommodate the annular ring. This ensures that the component can rest against the base component even near the joint location and can be joined in this position with the aid of the fastener.

[0009] The inventive method permits two different process sequences. According to a first process sequence, the fastener is first fastened by itself to the base component, for example by welding. Next, the opening of the component is placed on the fastener and is brought to the predefined joining position. An alternative process sequence provides that the fastener is first inserted through the opening in the component, and the fastening of the fastener to the base component takes place afterward. However, this process sequence requires either a special welding process, for example resistance welding, or a component that consists of an electrically nonconductive material. Furthermore, it is possible to electrically insulate the fastener from the component in order to weld it on by drawn arc welding with it being preassembled in the component.

[0010] According to the invention, the fastener includes a sleeve with a fastening end, and a mandrel located within and projecting out of the sleeve by means of which the sleeve can be plastically deformed to increase its diameter. The sleeve preferably has a closed bottom which is designed for attachment by welding, in particular by means of the electric drawn arc welding method. The mandrel has a head of larger diameter adjacent to the fastening end, a shank of smaller diameter projecting from the sleeve, and a constricted tear-off section between the head and the shank at which the shank can be detached from the head. The sleeve of the fastener preferably has a cylindrical outer surface, and its inner surface tightly surrounds the head, shank, and tear-off section of the mandrel. Brief Description of Drawings

[0011] The invention is explained in detail below on the basis of example embodiments which are shown in the drawings. Shown are:

[0012] Figure 1 a first embodiment of a fastener according to the invention,

[0013] Figure 2 a second embodiment of a fastener according to the invention, [0014] Figure 3 a cross-section through a joint established according to the inventive method, and

[0015] Figures 4 through 12 a schematic representation of the individual steps in establishing a joint according to the inventive method. Best Mode for Carrying Out the Invention

[0016] The fastener 1 shown in Figure 1 consists of a cylindrical sleeve 2 with a closed bottom 3. Located within the sleeve 2 is a mandrel 4, which has a head 5, a shank 6, and a constricted tear-off section 7 therebetween. The head 5 is directly adjacent to the bottom 3 and has the shape of a cylinder. On the side facing the tear-off section 7, the head 5 has a shoulder 8, which is shaped like a truncated cone and forms the transition to the smaller diameter of the tear-off section 7. The tear-off section 7 is likewise cylindrical. It is adjoined by a radial shoulder of the cylindrical shank 6, whose diameter is greater than the diameter of the tear-off section 7 and smaller than the diameter of the head 5. The majority of the length of the shank 6 projects out of the sleeve 2, and the free end of the shank is chamfered into a truncated cone shape. The length of the shank 6 is primarily determined by the design of the setting tool, whose jaws require a sufficiently large engagement surface on the shank 6 to be able to transmit to the shank 6 the tensile force needed for deformation and tear-off.

[0017] In the variant embodiment of a fastener 1a shown in Figure 2, the free end of the shank 6a is provided with a spherical cap 9. The spherical cap 9 has a larger diameter than the shank 6a, and its underside forms a shoulder 10, at which a tool can engage. This makes it possible to keep the axial length of the shank 6a shorter. In addition, the spherical cap 9 has the advantage that it facilitates placement and passage of the opening of the component to be mounted. The maximum diameter of the spherical cap 9 is not larger than the outside diameter of the sleeve 2a.

[0018] The sleeve 2a of the fastener 1 a has an open bottom with a collar 11 , which overhangs relative to the head 5a and forms the welding end. This design makes it possible to simplify manufacture of the fastener 1a.

[0019] Figure 3 shows a joint established according to the invention between a base component 12 and a component 14. Here, base component 12 designates the component to which the fastener 1 is attached by welding or in another appropriate manner prior to plastic deformation. Preferably, the base component 12 and the component 14 are metal sheets or panels, such as are used in car body construction in the automotive industry.

[0020] The bottom 3 of the sleeve 2 is welded onto the base component 12 in the embodiment shown in Figure 3. For the purpose of assembly, the component 14 is provided with an opening 15 and, on its underside 17 facing the base component, a recess 16 formed by a raised rim. In order to retain the component 14 in the illustrated position relative to the base component 12, a seat 18 is formed by expansion of the wall of the sleeve 2 on which the underside 17 of the component 14 is supported. On the top 19 of the component 14, the upper edge area of the sleeve 2 that has been deformed by swaging forms an annular opposing head 20, which laps over the edge of the opening 15, thus holding the component 14 in place on the seat 18. The head 5 of the mandrel 4 has been pulled into the position shown in the drawing during expansion of the sleeve 2. As a result of the resistance to further expansion of the sleeve 2 presented by the component 14 at this point, the head 5 could not move upward further, so that after a certain increase in the tensile force acting on the mandrel, and an associated swaging of the opposing head 20, the shank of the mandrel 4 is torn off at the tear-off section 7.

[0021] The establishment of the joint shown in Figure 3 is described below using Figures 4 through 12.

[0022] In Figure 4, the bottom 3 of the fastener 1 is welded onto the base component 12 by means of a welding apparatus 30 using the electric drawn arc welding method. The welding current here can be transmitted to the sleeve 2 through the mandrel 4, since the electrical contact between the two parts is' very good.

[0023] Figure 5 shows the fastener 1 welded to the base component 12 after removal of the welding apparatus 30.

[0024] As can be seen in Figure 6, in the next step the component 14 is positioned with its opening 15 on the sleeve 2 of the welded-on fastener 1. The position that the component 14 assumes here corresponds to the stress-free position that results from various contact points between the base component 12 and the component 14, which are not visible in the drawing.

[0025] Next, as shown in Figure 7, the tip 32 of a setting tool is placed on the shank 6 of the mandrel 4, and its front end 33 is brought into contact with the end of the sleeve 2.

[0026] In Figures 8 and 9, the shank 6 of the mandrel 4 is drawn into the tip 32, in which process the setting tool bears against the sleeve 2. During this process, the region of the sleeve 2 located between the base component 12 and the component 14 is plastically deformed progressively from the bottom to the top by the head 5 and is expanded to a larger diameter. In Figure 9, the region of the sleeve 2 expanded by the head 5 begins to bear against the opening 15 of the component 14, so that the resistance posed by the sleeve 2 to expansion by the head 5 grows. The tensile force on the mandrel 4 and the bearing force on the tip 32 increase accordingly. As is evident from Figure 10, this has the result that the material of the sleeve 2 is now swaged on both sides of the opening 15 of the component 14, and surface contact inside the hole occurs between the sleeve 2 and the edge of the opening 15.

[0027] The further increase in the tensile force on the mandrel 4, and thus also in the bearing force on the tip 32 opposing it, accomplishes the complete formation of the seat 18 and the opposing head 20, as is shown in Figure 11. Finally, the tear-off section 7 tears off, with the result that the shank of the mandrel 4 is drawn into the setting tool; see Figure 12.

[0028] The joining method described has a number of advantages. It is important, first of all, that the size of a gap present between the base component and component is preserved during the joining process, which is to say that the components are not distorted. The size of the gap between the base component and component can vary between zero and a value limited by the length of the sleeve. No projection is produced on the back of the base component, and the entire joining process can take place from one side of the base component. No opening is required in the base component, so that the tightness of the connection to the base component is ensured in all cases. The exact alignment of two holes, one in the base component and one in the component, as is required for riveted or screwed connections, is no longer required. Production of the joint uses only a single fastener, in which the fastening functions to be used are integrated. The production of the joint uses existing and proven technologies such as stud welding for welded attachment of the sleeve, and the deformation of the fastener with the aid of a drawing tool, such as is known for the setting of blind rivets. The connection is permanent and vibration resistant, and is economical to produce.

[0029] Although exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. Method for fastening at least one component to a base component with the aid of a fastener that has a sleeve with a fastening end and, located within the sleeve, a mandrel by means of which the sleeve can be plastically deformed to increase its diameter, wherein the fastener is fastened by its fastening end to the base component, the component is aligned in a predetermined position relative to the base component and the fastener, wherein the fastener projects through an opening in the component, the diameter of the sleeve is enlarged with the aid of the mandrel in a region surrounded by the component, and an adhesion, in particular surface contact with the inside of the hole, is produced between the sleeve and the component, and the mandrel is subsequently at least partially removed.

2. Method according to claim 1 , characterized in that the diameter of the sleeve is enlarged in a region between the component and the base component with the aid of the mandrel, and a seat is formed on the underside of the component.

3. Method according to claim 1 or 2, characterized in that an opposing head is swaged onto the top of the component.

4. Method according to one of trie preceding claims, characterized in that the sleeve is deformed such that it completely fills the opening in the component.

5. Method according to one of the preceding claims, characterized in that the component is provided on its underside with a recess surrounding the opening.

6. Method according to one of the preceding claims, characterized in that the fastening end of the sleeve is welded onto the base component.

7. Method according to one of the preceding claims, characterized in that the component is placed on the fastener after the fastener has been fastened to the base component.

8. Method according to one of the preceding claims, characterized in that the sleeve is plastically deformed by a head of the mandrel, and the head is separated from the mandrel after production of the adhesion or of the seat and opposing head, and is left behind in the deformed sleeve.

9. Method according to one of claims 1 through 7, characterized in that the mandrel is completely removed from the sleeve after production of the adhesion or of the seat and opposing head.

10. Fastener for fastening at least one component to a base component, including a sleeve with a fastening end, and, located within and projecting out of the sleeve, a mandrel by means of which the sleeve can be plastically deformed to increase its diameter.

11. Fastener according to claim 10, characterized in that the sleeve has a closed bottom that is designed for attachment by electric welding using the drawn arc welding method.

12. Fastener according to claim 10, characterized in that the sleeve has an open bottom and a collar that overhangs relative to the mandrel and forms a welding end.

13. Fastener according to one of claims 10 through 12, characterized in that the mandrel has a head of larger diameter adjacent to the fastening end, a shank of smaller diameter, and a constricted tear-off section between the head and the shank, and in that the sleeve has a cylindrical outer surface, and its inner surface tightly surrounds the mandrel.

14. A fastener assembly comprising: a base, a component including a hole, and a fastener connecting the base and the component, the fastener having a bottom welded to the base, a sleeve section extending away from the bottom towards the component and an opposing head opposite the bottom; wherein the sleeve is generally hollow and a contains a mandrel head; wherein the fastener is connected to the component at edges of the component forming the hole, the edges of the component being held between a seat in the fastener and the opposing head.

15. The fastener assembly according to claim 14, wherein the component includes a recess adjacent the hole.