Joining element and method for joining at least two workpieces

The present invention relates to a connecting element for interconnecting at least two workpieces, which connecting the shaft and one end of the shaft radially projecting beyond the outer side of the shaft. Within the holding portion of the shaft having the element head and the rotational drive structure on the connecting element head and extending from the lower side of the connecting element head, at least a pair of closed annular protrusions are arranged on the holding portion. And that at least a pair of annular protrusions are not completely arranged in a plane extending perpendicular to the vertical axis of the shaft, and the pair of two annular protrusions along the outer circumference. The spacing between them is of a different size from each other, or the two annular projections in a pair of annular projections are arranged so that they are parallel to each other, and the front end of the shaft is a tapered hole. It is configured as a forming part.

Such connecting elements are known from Patent Document 1, which is an international patent application gazette.

<p num="0003"><patcit num="1"><text>International Publication No. 2015/0221 24 Pamphlet</text></patcit></p>

<p num="0004"> The present invention improves connecting elements and methods for connecting at least two workpieces.</p>

<p num="0005"> To this end, the present invention is a connecting element for interconnecting at least two workpieces in a radial direction across the outer side of the shaft and one end of the shaft. In the holding portion of the shaft having a connecting element head protruding into a right angle and a rotational drive structure on the connecting element head and extending from the lower side of the connecting element head, at least a pair of closed annular protrusions are the holding portion. The pair of 2s that are located on top and whose at least one annular protrusion is not completely located in a plane extending perpendicular to the vertical axis of the shaft and along the outer circumference. A connecting element is provided in which the spacing between the two annular projections is of a different size from each other or the two annular projections of a pair of annular projections are arranged so that they are parallel to each other. The front end of the shaft is configured as a tapered hole forming portion, and the maximum outer diameter of the hole forming portion is 3% to 10% smaller than the maximum outer diameter of the annular protrusion, preferably 5. %small.</p><p num="0006"> Surprisingly, it has been demonstrated that this dimensioning of the maximum outer diameter of the hole-forming portion produces particularly good results when connecting at least two workpieces. Therefore, the holes created after the hole formation by the hole forming portion are somewhat smaller than the outer diameter of the shaft within the area of the annular protrusion. In particular, the diameter of the hole formed by the hole forming portion is about 3% to about 10% smaller than the outer diameter of the annular projection. Therefore, the holding portion must actually be pushed into the formed hole by shaft directional pressure, but also secure holding of the annular projection in the formed hole is also achieved. In this case, after the hole formation by the hole formation, the formed hole and the surrounding material are very hot and each is at least partially melted, or at least paste-like. , Must be considered. Therefore, the holding portion with the annular protrusion will be pushed in with only a small amount of force in the shaft direction. In this case, the force in the shaft direction will be selected so that there is no risk of the overlapping workpieces being curved or deformed, respectively. Therefore, the lightweight metal sheets can be interconnected using the connecting elements according to the invention without having to worry about the relatively large deformation of the lightweight metal sheets. This is a decisive advantage of the connecting element according to the present invention, as compared to, for example, a nail that is simply driven in the shaft direction through a workpiece to be connected. Once the retaining portion has been pushed into the hole formed by the hole forming portion, the material surrounding the hole flows into the intermediate space between the annular projections, but at least shrinks during cooling and thus is annular. It will ensure a secure fixation of the protrusions. Because the distance between the pair of two annular processes along the outer circumference is different from each other, or because both of the pair of annular processes of the annular process are parallel to each other and on the vertical line. Since it is arranged to be at least partially tilted relative to it, the fixation of the connecting element is achieved by twisting the connecting element after the connecting element has been completely pushed into the formed hole. right. Therefore, the durability of the connecting element against unscrewing is increased, and the mutual deviation (mutual) between the two workpieces is increased. Even bias) will be realized. It is possible to achieve significantly shorter connection times compared to flow drilling screws.</p><p num="0007"> In the improvement measures of the present invention, the maximum outer diameter of the hole-forming portion is larger than the core diameter of the shaft between the annular protrusions.</p><p num="0008"> Therefore, the diameter of the hole formed by the hole forming portion is intermediate between the core diameter of the shaft between the annular protrusions and the outer diameter of the annular protrusions. Thus, secure retention of the annular process within the formed hole may be achieved, and moreover, the heated material surrounding the hole may flow between the annular process, or at least its. The holes can be significantly reduced during cooling so that a secure retention of the annular projection and thus a secure retention of the connecting elements is achieved.</p><p num="0009"> In the improvement measures of the present invention, an acceleration region having a constant outer diameter is arranged between the end of the hole forming portion on the head side and the starting point of the holding portion, and in this case, acceleration is performed. The outer diameter of the area is smaller than the maximum outer diameter of the hole forming portion.</p><p num="0010"> These acceleration zones allow the bolt to be accelerated in the shaft direction as a result of the shaft direction pressure applied to the bolt relative to the two workpieces after the hole formation by the hole forming portion. It will be realized. Then, when the holding portion with the annular protrusion contacts the wall of the formed hole, the holding portion with the annular protrusion is the connecting element because the bolt is already very fast or has a large thrust. It is pushed very quickly into the formed hole until the lower side of the head rests on the upper side of the upper workpiece.</p><p num="0011"> In the remedy of the present invention, the outer diameter of the acceleration zone is greater than or equal in size to the core diameter of the shaft between the annular projections.</p><p num="0012"> With respect to the outer diameter of the acceleration zone, it is clear that the acceleration zone is smaller than the inner diameter of the hole formed by the hole forming portion. Therefore, during push-fitting in the shaft direction, in combination with the rotation of the connecting element at will, between the formed hole and the connecting element immediately after the acceleration zone enters the hole. Friction is greatly reduced. Therefore, the connecting element will be under pressure in the direction of the shaft and will be facilitated into the hole. In this case, the acceleration zone already begins at the maximum diameter of the hole forming portion and ends at the starting point of the retaining portion, i.e. at the first annular process. Therefore, the diameter of the shaft will initially decrease as it progresses from the maximum diameter of the hole forming portion to the cylindrical portion of the acceleration zone.</p><p num="0013"> In the remedy of the present invention, the length of the acceleration zone, in particular the length of the cylindrical portion of the acceleration zone, is between 20% and 50% of the length of the hole forming portion, preferably 30% thereof. .. The length of the hole-forming portion and, in addition, the length of the acceleration zone, in particular the length of the cylindrical portion of the acceleration zone, is adapted to the thickness of the interconnected workpiece. The formation of an acceleration zone between 20% and 50% of the length of the hole forming portion, preferably 30% of which, until the lower side of the connecting element head rests on the surface of the outer workpiece. Ensures proper acceleration of the connecting element to the workpiece so that a very quick indentation fit of the retaining portion into the hole is achieved.</p><p num="0014"> In the remedy of the present invention, the hole-forming portion has a rounded tip at its free end. In the remedy of the present invention, the hole forming portion has a polygonal cross section, at least within the area of its free end. A reduction in drilling time during hole formation is achieved by such a polygonal cross section, which may follow the tip where it is advantageous to be round. In the remedy of the present invention, this polygonal cross section has rounded corners. In the remedy of the present invention, the polygonal cross section is configured to be a triangle with rounded corners. Particularly reliable results during hole formation are achieved by triangles with rounded corners, which rounded corners may be connected by convexally curved lateral edges.</p><p num="0015"> In the remedy of the present invention, the acceleration zone has a circular cross section. Circular holes are created by the hole forming portion, even when the cross section of the hole forming portion is polygonal. Even when the acceleration zone is located inside the hole, there is friction between the connecting element and the wall of the hole so as to accelerate the connecting element against the workpiece and even against the hole. It should be reduced as much as possible. To achieve this, if the cross section of the acceleration area is circular, the circular cross section of the acceleration area is very suitable because the outer walls of the acceleration area are evenly spaced from the entire wall of the hole. ing.</p><p num="0016"> In the remedy of the present invention, the holding portion has a circular cross section. The holding portion is provided by its annular protrusion to mesh with the wall of the hole formed by the hole forming portion. Also in this case, it is advantageous that the circular cross section of the holding portion is advantageous, and at least the outer peripheral portion of the holding portion is circular.</p><p num="0017"> The object of the present invention is further realized by a method for connecting at least two workpieces, in which case the workpieces are arranged so as to overlap each other and the connecting element according to the present invention is rotated. The pressure in the shaft direction is applied to the connecting element until it is placed on the work piece outside the work piece and the lower side of the connecting element rests on the surface of the outer component facing the connecting element head. It is affected by.</p><p num="0018"> Since the connecting element is rotated and placed on the outer workpiece of the workpiece, the free end of the hole forming portion comes into contact with the outer workpiece. The rotation of the hole-forming portion heats the workpiece locally violently, and the hole-forming portion forms a hole having a passage in the two workpieces. For this reason, apart from the rotation of the hole forming portion, a shaft directional pressure acting on the connecting element is also required. This shaft directional pressure is maintained until the lower side of the connecting element rests on the surface of the outer component facing the connecting element head. This is a major difference from flow drill screws. In the case of a flow drill screw with a thread in the holding portion, the shaft direction pressure is increased once the thread, which is typically a tapping screw, meshes into the wall of the hole that has been formed by the hole forming portion. Not needed. In this case, a simple rotation of the flow drill screw pulls the flow drill screw into the hole by the thread until the lower side of its screw head rests. In the case of the method according to the invention and the connecting element according to the invention, the connecting element is not provided with a thread in the holding portion, and therefore the connecting element is press-fitted into the hole that has been formed by the hole forming portion. Shaft pressure must be maintained so that it can be forced. In the method according to the invention, in this case, the indentation fitting in the shaft direction may be performed in response to the connecting element continuing to rotate. In contrast to flow drill threads, a significant reduction in the time required to establish a connection can be achieved by using the connecting elements according to the invention and the methods according to the invention.</p><p num="0019"> In the remedy of the present invention, the connecting element continues to rotate when the lower side of the connecting element head is placed on the surface of the outer component. Surprisingly, it has been demonstrated that further rotation of the connecting element does not impair the holding power of the connecting element, even after the head of the connecting element has finished resting on the outer workpiece. In particular, hole wall tears, such as those that always occur with flow drill screws when the rotation cannot be stopped immediately after the head of the flow drill screw rests on the outer workpiece, can occur. Absent.</p><p num="0020"> In the improvement measures of the present invention, when the lower side portion of the connecting element head is placed on the outer component, the rotation angle of the rotational movement of the connecting element is larger than 360 °. Not only is it easy to fix the connecting element in the workpiece when arranging the lower side of the connecting element head. Only rotations less than 360 ° will be needed for such sticking. Surprisingly, when the connecting element head is placed, a rotation angle of more than 360 ° has also been demonstrated to provide a very reliable holding force for the connecting element. The walls of the holes that have been formed by the hole-forming portions, or the materials that form the walls, will each be vigorously heated and will flow into the intermediate spacing between the annular projections, or in a paste state. And each will move between the annular processes. This is aided by further rotation of the connecting element when the connecting element head is placed on the outer component. Vigorous heating of the material forming the wall of the forming hole further causes shrinkage of the hole during cooling. Therefore, the fixing or blocking of the holding portion of the connecting element in the forming hole is facilitated respectively.</p><p num="0021"> In the improvement measures of the present invention, when the lower side portion of the connecting element head is arranged on the outer workpiece, the connecting element is driven to perform a rotational motion until the rotation of the connecting element is decelerated to a stopped state. Will not be done. Therefore, the rotational drive of the connecting element may be stopped when the connecting element head is arranged, and the connecting element may be naturally decelerated to the stopped state by simple friction.</p><p num="0022"> In the remedy of the present invention, when the lower side portion of the connecting element head is placed on the outer component, the connecting element continues to be rotated by a predetermined angle. In this way, the determined rotational movement may be performed at the time of the arrangement, and in this case, the rotational movement may easily have a rotation angle of more than 360 °.</p><p num="0023"> Yet another feature and advantage of the present invention will become apparent from the claims and the later description of preferred embodiments of the invention in relation to the drawings.</p>

<figref num="1">A side view of the connecting element according to the present invention is shown.</figref><figref num="2">A cross-sectional view of the connecting element of FIG. 1, which is parallel to the vertical line, is shown.</figref><figref num="3">A cross-sectional view of the acceleration zone of the connecting element of FIG. 1, which is perpendicular to the vertical line, is shown.</figref><figref num="4">A cross-sectional view of the hole forming area of the connecting element of FIG. 1, which is perpendicular to the vertical line, is shown.</figref><figref num="5">A partially enlarged explanatory view of the connecting elements of FIG. 1 is shown.</figref><figref num="6">Another explanatory diagram of the connecting elements of FIG. 1, which is partially enlarged, is shown.</figref><figref num="7">A step of connecting two workpieces by the connecting element of the present invention is shown.</figref><figref num="8">A step of connecting two workpieces by the connecting element of the present invention is shown.</figref><figref num="9">A step of connecting two workpieces by the connecting element of the present invention is shown.</figref><figref num="10">A step of connecting two workpieces by the connecting element of the present invention is shown.</figref>

The explanatory view of FIG. 1 shows a connecting element 10 according to the present invention according to a preferred embodiment of the present invention. The connecting element 10 has a connecting element head 12 and a shaft 14. The connecting element head on the upper side of the connecting element comprises a drive structure 16. The lower side portion 18 of the connecting element head 12 is provided with an annular groove 20 surrounding the periphery (see FIG. 2), in which the lower side portion 18 of the connecting element 10 is an outer workpiece. It is provided to accept the dents in the material of its outer workpiece when placed on top. A flat annular surface 22 arranged radially outward and perpendicular to the central vertical axis of the connecting element 10 is adjacent to the annular groove 20. The drive structure 16 allows the connecting element 10 to be driven in only one direction of rotation and that a downward acting shaft pressure in FIG. 1 is applied to the connecting element head 12.

The protruding area of the shaft 14 is shown in square brackets in FIG. A holding portion 24 having a plurality of annular protrusions 26, 28 is initially arranged so as to proceed from the lower side portion 18 of the connecting element head 12. The holding portion 24 is followed by an acceleration zone 30 having a cylindrical portion, which is the furthest annular projection from the lower side 18 of the connecting element head 12, as indicated by the length of the brackets. It extends from 26 to the starting point of the hole forming portion 32. Therefore, this acceleration zone has yet another extension zone, in which the outer diameter of the acceleration zone 30 is from the constant outer diameter within the cylindrical area to the maximum outside of the hole forming portion 32. It increases to the diameter. The hole forming portion 32 is tapered in the direction toward the free end of the shaft 14 which terminates at the rounded tip 34.

FIG. 4 shows a cross section passing through the hole forming portion 32, which extends at right angles to the central vertical axis of the connecting element 10. It can be seen that the hole forming portion 32 has a polygonal cross section in the shape of a triangle with rounded corners. Each of the round corners is interconnected by a slightly convex curved lateral edge. The hole forming portion 32 has such a polygonal cross section over its entire length up to the tip 34.

FIG. 3 shows a cross section of the connecting element 10 in the cylindrical portion of the acceleration zone 30 that is perpendicular to the central vertical axis. The connecting element 10 within the cylindrical acceleration zone 30 has a circular cross section. The cross section of the shaft 14 is also circular within the holding portion 24.

The enlarged view of FIG. 5 shows only a part of the hole forming portion 32, the acceleration area 30, and the holding portion 24 in the form of an enlarged explanatory view. The maximum outer diameter of the hole forming portion 32 is located at the end of the hole forming portion 32 on the head side and is indicated by the collation code A. The diameter of the acceleration zone 30 within the cylindrical zone is indicated by reference numeral B. The maximum outer diameters of the annular protrusions 26 and 28 are indicated by reference numeral C. The outer diameters of the annular protrusions 26 and 28 are the same so that the holding portion 24 has a cylindrical enveloping surface. The core diameter of the holding portion 24 is indicated by the symbol E.

In the enlarged explanatory view of FIG. 5, it can be seen that the two annular protrusions 26 and 28 always form a pair. The outer diameter of the annular protrusion 28 is actually the same size as the outer diameter of the annular protrusion 26. However, the vertical spacing of the connecting element 10 between the two annular protrusions 26 and 28 along the outer circumference is variable in size and increases from right to left in the explanatory view of FIG. And it decreases from left to right. Therefore, the annular projection 28 is arranged so as to be inclined with respect to the vertical axis line of the connecting element 10, while the annular projection 26 extends in a direction perpendicular to the vertical axis line.

Alternatively, in a manner not shown in the figure, the annular projections 26, 28 may be further arranged to be parallel to each other, in which case the two two annular projections in this case are It is not completely disposed in a plane extending perpendicular to the vertical axis of the shaft, and is therefore inclined with respect to, for example, the vertical axis.

For specific examples of possible designs of the annular projections 26, 28, reference is made to Patent Document 1 by the same applicant as the applicant, and the content of this patent document as a whole is incorporated herein by reference. There is. In this way, the annular projection may extend only partially at an angle with respect to the vertical axis.

Prior to the start of the acceleration zone 30, three annular projections 26, all extending parallel to each other, are arranged consecutively when viewed in the vertical direction. In FIG. 1, it can be seen that a total of three pairs of annular protrusions 26 and 28 are continuously arranged in the holding portion 24. This is followed by three annular protrusions 26 extending perpendicular to the vertical axis before the acceleration zone 30 begins.

The cylindrical portion of the acceleration zone 30 begins after the last annular protrusion 26. This cylindrical portion has an outer diameter B. After the end of the cylindrical portion, the outer diameter of the acceleration zone 30 increases until the acceleration zone 30 transitions to the hole forming portion 32 at the maximum diameter A. The hole forming portion 32 is then continuously tapered until it reaches the rounded tip 34.

The maximum diameter A of the hole forming portion 32 in the case of the embodiment shown in this figure is 5% smaller than the maximum outer diameter C of the annular protrusions 26 and 28. For the present invention, the maximum outer diameter A will be 3% to 10% smaller than the maximum outer diameter C.

The outer diameter B of the cylindrical portion of the acceleration zone 30 in the illustrated embodiment corresponds to the core diameter D of the shaft 14 in the holding portion 24. The maximum outer diameter A of the hole forming portion 32 is larger than the diameter B in the cylindrical portion of the acceleration zone 30, and further larger than the core diameter D of the holding portion 24. The maximum outer diameter of the hole forming portion 32, and therefore the diameter of the hole formed in the workpiece located so as to overlap each other, is the outer diameter C of the annular projections 26 and 28, respectively. , The size between the core diameter D of the holding portion or the outer diameter B of the cylindrical portion of the acceleration zone 30.

The explanatory diagram of FIG. 6 shows a part of the connecting element 10 of FIG. 1 already shown in FIG. FIG. 6 is used to show the length ratio between the hole forming portion 32 and the acceleration zone 30. The hole forming portion 32 has a length E from a rounded tip 34 to a maximum diameter A. The acceleration zone 30 has a length F from the maximum diameter A of the hole forming portion 32 that simultaneously forms the end of the hole forming portion 32 to the base of the first annular projection 26. In the case of the connecting elements according to the invention, the length F of the acceleration zone 30 is between 20% and 50% of the length E of the hole forming portion 32. In the illustrated embodiment, the length F of the acceleration zone 30 is about 30% of the length E of the hole forming portion 32.

It is clear that the length ratio shown in FIG. 6 and the diameter ratio shown in FIG. 5 provide outstanding results when connecting two workpieces with the connecting elements according to the invention. It has become. In particular, very short cycle times will be achieved during hole formation and even when the holding portion 24 is pushed in and fitted towards the shaft. Overall, a reduction of up to 50% in cycle time will be achieved compared to flow drill screws or other connecting elements. The connecting element 10 according to the invention and the method according to the invention are used, for example, to connect an aluminum panel to a steel panel, or even to connect two aluminum panels. In this case, when the two workpieces are adhesively joined, the connecting element 10 may only serve to integrally crimp the workpieces until the adhesive is completely cured.

The explanatory views of FIGS. 7 to 10 show various method steps in carrying out the method according to the present invention. In each case, the illustration of connecting element 10 is schematic. Further, in contrast to what can be assumed based on the configurations of FIGS. 7 to 10, the two workpieces 40, 42 interconnected during the connecting process are stationary and of the same height. It is pointed out that there is even more.

In FIG. 7, the rotating connecting element 10 is already pressed by the tip 34 of the hole forming portion 32 in the direction of the two workpieces 40, 42 with a shaft direction pressure P. A step of the method according to the invention is shown, which has penetrated the two workpieces 40, 42. In FIG. 7, the maximum diameter A of the hole forming area 32 is located so as to be substantially at the same level as the surface of the outer workpiece 40.

The connecting element 10 is then further rotated (see FIG. 8) and continues to be penetrated by the shaft direction pressure P. In this case, the shaft direction pressure P does not necessarily have to be constant over time. At this point, the hole forming portion 32 has completed forming the hole and the passage 44 in the lower workpiece 42. Acceleration zones 30 are, at this point, located within the area of the hole or within the area of passage 44, respectively. The diameter B in the acceleration zone 30, which is reduced compared to the maximum outer diameter A at the end of the hole forming zone 32, causes the connecting element 10 to succumb more to the shaft direction pressure P and therefore two workpieces. It gives rise to the possibility of being accelerated in the direction of objects 40, 42.

This facilitates shaft-wise push-fitting of the connecting element 10 into the holes in the workpieces 40, 42 that have been formed by the hole-forming portions 32. The continuously maintained shaft pressure P and the similarly maintained rotation cause the holding portion 24 to penetrate through the holes that have been formed in the workpieces 40, 42 by their annular projections (FIG. FIG. See 9).

Penetration into the two workpieces 40, 42 is carried out until the lower side of the connecting element head 12 rests on the surface of the outer workpiece facing the head 12 (see FIG. 10). At the position of FIG. 10, further rotation of the connecting element 10 is performed according to the method according to the invention. This rotation will occur over an angle greater than 360 ° when the lower side of the connecting element head 12 is placed. It is realized in connection with the present invention that the rotary drive device of the connecting element 12 (not shown in FIGS. 7 to 10) is stopped or the connecting element 10 is continuously driven. While the connecting element 10 at the position of FIG. 10 continues to rotate, the material forming the holes in the workpieces 40, 42 flows or flows between the annular protrusions 26, 28 of the holding portion 24, respectively. It will move into the intermediate space between the annular processes 26 and 28. This may be caused by the actual flow movement of the heated material. However, since the temperature of the material forming the holes in the workpieces 40 and 42 is lowered by itself, the diameter of the holes is also reduced, and the wall of the holes and the annular protrusions 26 and 28 of the holding portion 24 are engaged with each other. Occurs.

Therefore, by using the connecting element 10 according to the present invention and by using the above method according to the present invention, an extremely short cycle time will be realized when connecting the two workpieces 40 and 42. As described in detail, the opposing surfaces of the workpieces 40, 42 may be coated with an adhesive, the connecting element 10 additionally anchors the two workpieces to each other, and the adhesive It works to hold the two workpieces in a state of being crimped to each other until it is completely cured.

10 connecting elements 12 connecting element head 14 shaft 16 drive structure 24 Holding part 26, 28 annular protrusion 30 Acceleration area 32 hole forming part 40, 42 Work piece