Screws for direct screwing into components

Abstract

This invention relates to a screw (10) for direct screwing into a component, particularly a component made of a light metal material, comprising a head and a shank, wherein the shank is provided with a thread (20), the outer radius (RA) of which decreases from a cylindrical support region (TB) having a constant support region radius (RT) towards the screw tip (12) within a tip region (SB), wherein the thread (20) has guide sides (46, 56) toward the screw tip (12) and The load sides (42, 52) facing the aforementioned screw head (18), wherein the aforementioned guide sides (46, 56) and the aforementioned load sides (42, 52) are connected by threaded tips (44, 54), wherein the outline of the aforementioned threaded tips (44, 54) from the aforementioned guide sides (46, 56) to the aforementioned load sides (42, 52) follows an elliptical path along an ellipse (SE) defining the aforementioned threaded tips, wherein the vertex (SP) of the semi-major axis of the aforementioned ellipse (SE) is located in the aforementioned threaded tips, the aforementioned ellipse (SE) has transition points (UP1, UP2) with the aforementioned load sides (42, 52) and transition points (UP1, UP2) with the aforementioned guide sides (46, 56), wherein at the transition points (UP1, UP2) with the aforementioned load sides (42, 52), the tangent (T1) to the aforementioned ellipse forms a load side angle (LF) with the semi-major axis (HA) of the aforementioned ellipse (SE), and at the transition point (UP2) with the aforementioned guide sides (46, 56), the tangent (T2) to the aforementioned ellipse (SE) forms a load side angle (LF). The threaded tip is designed in such a way that an orthogonal line at the transition points (UP1, UP2) orthogonal to the tangents (T1, T2) intersects the semi-major axis (HA) at the intersection point (BP1; BP2). The characteristic is that the distance between the intersection point (BP1; BP2) and the transition point (UP1, UP2) is less than 90% of the distance between the vertex (SP) and the intersection point (BP1; BP2).

Description

Screws for direct screwing into components The invention relates to a screw for screwing directly into a component, in particular a component made of light metal material. EP 1 053 405 B1 discloses a screw with a self-tapping thread, wherein the screw has a groove section at the front end, which has an oval cross section and a thread profile with a sharp thread tip. WO 95 / 14863 A1 discloses a self-tapping screw with a forming element placed on the thread line. This screw is intended to reduce the screw-in torque during thread forming in the nut material, which in principle increases with increasing screw-in depth. The screw has a profiled area in the front region, which extends radially beyond the basic thread, which extends substantially continuously from the shank to the tip. This profiled area is circumferentially limited and relatively short. In the support region, the screw has a calibration projection, which protrudes only slightly beyond the support thread, in particular by less than 0.08 mm. The screw reduces friction during the trenching process while still achieving good fixing properties.It is difficult to reliably produce such calibration projections, in particular by means of a rolling process, because the material required to form the calibration projections is not sufficiently available during the rolling process. Therefore, an object of the present invention is to further improve the fixing performance of the screw while maintaining a relatively low tapping torque. The solution for achieving the above-mentioned purpose of the present invention lies in the features of claim 1 and the features of its preamble. In a known manner, a screw for screwing directly into a component, in particular a component made of light metal, comprises a head with a driver and a shank, wherein the shank is provided with a thread. The outer radius of the thread decreases from a cylindrical support region within a tip region toward the screw tip, so that the outer radius of the thread at the end of the thread, which is spaced a certain distance from the head, is smaller than the outer radius in the support region. This tip region begins closest to the support region and extends to the screw tip, at which point the outer radius of the thread is smaller than the radius of the support region. The nut thread is produced in the nut material of the component by means of the thread in the tip region, into which the thread in the support region is screwed. The thread has a leading side facing the screw tip and a load side facing the screw head. The leading flank and the load flank are connected by a thread tip, wherein a contour line of the thread tip from the leading flank to the load flank resulting from the thread cross section follows an elliptical path along an ellipse defining the thread tip. According to the invention, the thread is designed in such a way that at the contact point in the transition to the load flank, the tangent to the ellipse and the semi-major axis of the ellipse form a load flank angle of, in particular, at most 30°, and at the contact point in the transition to the guide flank, the tangent to the ellipse and the semi-major axis of the ellipse form a guide flank angle of, in particular, at most 30°. Furthermore, the thread tip is designed in such a way that a perpendicular line perpendicular to the tangent line at the transition point intersects the semi-major axis at an intersection point. According to the present invention, the thread tip is further designed in such a way that the distance between the respective transition point and the respective intersection point is less than the distance from the respective intersection point to the apex of the thread tip. The distance between the transition point and the intersection point is ideally less than 90% of the distance from the intersection point to the apex of the thread tip. The transition from the oval thread tip to the thread flank is typically tangential. This makes the transition smoother, allowing material displaced by the thread tip to flow further along the thread flank with low friction, thereby reducing the tapping torque. The thread tip is designed to be sufficiently blunt so that only slight wear occurs. This reduces the deformation forces and screw-in torque associated with the trenching process. According to an ideal technical approach, the numerical eccentricity Epsilon of the aforementioned ellipse is between 0.5 and 1. The oval design of the thread tip provides a strong structure at the outermost thread tip, giving it excellent groove-forming properties. Furthermore, as the distance from the outermost thread tip toward the thread root increases, the displaced material encounters less resistance. This reduces the radial force required to deform the nut material, making it easier for the thread to penetrate the nut material. According to a particularly ideal improvement, the aforementioned thread is designed in such a way that the two tangents abutting the corresponding transition points intersect and form an intersection angle, i.e. a basic side angle of less than 25° and at most 60°, in particular less than 60°, in particular less than 45°. The corresponding tangents thus form a load flank angle and a guide flank angle with the semi-major axis. This semi-major axis is parallel to the normal plane of the screw center axis or forms an angle of less than 25° therewith. The guide and load flanks therefore correspond to a basic flank angle. This basic flank angle is ideally between 25° and 45°. This improves screw-in performance, especially in high-strength light metal materials. The distance between the transition point on the leading flank and the semi-major axis is greater than 1 / 3*tan (leading flank angle)*thread height. The distance between the transition point on the load flank and the semi-major axis is greater than 1 / 3*tan (load flank angle)*thread height. The thread height is the difference between the basic thread outer radius and half the thread root diameter. This design allows for a relatively narrow thread flank. Further ideally, the aforementioned thread tip can be further improved in some way so that a line connecting the corresponding transition point and the vertex of the semi-major axis at the thread tip forms a vertex angle of less than 55° with the semi-major axis. This ensures that the thread tip extends correspondingly slenderly, thereby improving penetration into the nut material. Ideally, this thread section can transition from its elliptical section into a straight section of the guide flank and / or load flank, wherein the guide flank and / or load flank in particular coincides with a tangent. In a further development of the invention, the guide flank and / or the load flank may extend along an elliptical path, the curvature of which is designed to be oriented in the opposite direction to the curvature of the ellipse at the thread tip. In this case, this curvature may be located immediately adjacent to the thread tip or the straight section of the guide flank and / or the load flank. The eccentricity of the elliptical path of the guide flank and / or the load flank is ideally smaller than the eccentricity of the ellipse defining the thread tip. This results in a significant widening of the thread towards the thread root, thereby increasing the shear strength and stability of the thread. According to another advantageous development of the invention, the semi-major axis of the ellipse defining the thread tip is inclined in the direction of the guide flank at an angle of not more than 10° relative to the normal plane to the screw center axis. The spacing between adjacent thread flanks at 90% of the thread height is in particular greater than 0.7 times the lead. Furthermore, at 90% of the thread height, the flank width can be less than 0.5 times the thread height. This provides a sufficiently small thread tip width. According to an advantageous improvement of the present invention, the thread has at least five radially extending projections in the tip region. These projections are circumferentially limited, which means that there are local minima between the projections. Furthermore, it is desirable that the cross section of the projections of the thread in the region of the screw tip is designed in such a way that these projections are oval in the region of the thread tip. Thus, in the region of the projections, the guide flank and the load flank are also connected by the thread tip, the contour of which is oval in cross section. In addition to the thread tip in the support area, these projections can also have an oval shape. By adapting the thread shape in the support area, the contact between the basic thread and the grooved nut thread can be improved, wherein the projections that essentially contribute to the grooved thread also achieve improved grooved properties. The thread outer radius locally follows the basic thread profile along the helix. This basic thread profile is interpolated by means of local minima of the thread outer radius in the tip region, located between these projections. In the region where the thread follows the interpolated basic thread profile, the thread is referred to as a basic thread, with a basic thread outer radius that increases continuously from the screw tip to the support region. To some extent, it can be said that the basic thread extends in the same way as a thread without projections. The basic thread outer radius ideally decreases strictly monotonically, in particular linearly, in the tip region and corresponds to the bearing region radius in the bearing region. The basic thread outer radius in the bearing region is derived from the outer diameter of the cylindrical envelope in the bearing region. The bearing region radius is constant over the entire area where the thread of the bearing region meshes with the thread pre-grooved in the tip region by the projections. Therefore, according to the present invention, no projections are provided in the cylindrical portion of the external thread, as such projections would negatively affect the screw-in performance since they cannot be reliably manufactured in this region. The aforementioned threads have a thread outer radius in the region of these projections that varies from the basic thread outer radius and is accordingly increased relative to the basic thread outer radius. Thus, each projection has a maximum thread outer radius along the circumference of the helix that corresponds to the maximum radius of the projection corresponding to that projection. This ensures that the thread outer radius increases or decreases along the helix within the region of this projection. According to the invention, at least two projections are designed as calibration projections, wherein the projection maximum radius of these calibration projections is of the same size and is simultaneously larger than the support area radius. The projection maximum radius of these calibration projections defines the calibration radius. By providing at least two calibrating projections, initially only the calibrating projection closest to the screw tip provides trenching efficiency. At least one calibrating projection spaced further away provides no or only significantly reduced trenching efficiency until the calibrating projection closer to the screw tip wears out. In this case, the subsequent calibrating projection, located toward the support area, assumes the trenching function until the calibrating projection closer to the screw tip wears out. This allows the support thread to engage the preformed thread in the component, which is preformed in a largely defined manner, with a longer screw-in stroke and the associated higher trenching efficiency. This reduces the screw-in torque. Furthermore, the screw-in torque is kept low and limited to a small range by the screw according to the invention, since the additional trenching efficiency provided by the calibration projection only occurs when at least one calibration projection close to the screw tip is worn. The calibration projection is located in an area where the outer radius of the basic thread is reduced. Therefore, the difference to the outer radius of the basic thread is greater than the radius of the support area. Even if the difference between the calibration radius (i.e., the maximum radius of the calibration projection) and the radius of the support area is small, such calibration projections can be manufactured more reliably because the material for forming the calibration projection is then readily available. Ideally, the difference between the maximum radius of the calibration projection (i.e., the calibration radius) and the radius of the support area is very small, in particular less than 0.1 mm. Ideally, at least three calibrating projections with the same maximum projection radius are provided. Thus, there is one calibrating projection closest to the screw tip, which still provides a relatively low trenching efficiency, and two further calibrating projections located further away from the screw tip. After the calibrating projection closest to the screw tip wears out, the further spaced calibrating projections can be used to precisely shape the thread in the component. This design is more advantageous the harder the component and nut materials are. Furthermore, at least three preformed protrusions are arranged between the calibration protrusion and the frontmost screw tip. The respective protrusion maximum radius of these preformed protrusions is smaller than the maximum protrusion radius of the calibration protrusion, i.e., the calibration radius. Furthermore, the respective maximum protrusion radius of the preformed protrusions decreases toward the screw tip. This allows for a gradual shaping of the nut material. In this case, the difference in the maximum protrusion radius of successive protrusions is ideally selected so that each preformed protrusion provides approximately the same trenching efficiency. According to an ideal technical approach, the outer radius of the basic thread increases from the screw tip in the tip region in the same manner as the maximum radius of the preformed projection increases. The interpolation curve of the maximum radius of the projection is particularly parallel to the interpolation curve of the local minimum. Ideally, there is a local minimum of the thread outer radius between the radius of the support region and the maximum radius of the first projection toward the screw tip. At this local minimum, the thread outer radius is smaller than the support region radius. This means that the projection in front of the support region toward the head also descends to the level of the basic thread, whose outer thread diameter is smaller than the support region radius at this point. Consequently, the first projection, starting from the support region and heading toward the screw tip, is located entirely in the tip region. The ratio of the thread outer radius at the first local minimum to the bearing area radius is ideally less than 0.996. This achieves a sufficiently large difference in the thread outer radius to provide sufficient material to form the projection. According to another advantageous technical measure, the aforementioned thread is designed in such a way that the ratio of the percentage by which the calibration radius exceeds the minimum mean value to the percentage by which the calibration radius exceeds the radius of the bearing area is greater than 1.4. The minimum average value is the average of the thread outer radius at the first local minimum and the thread outer radius at the second local minimum. The first local minimum is located between the support area and the first protrusion closest to the support area in the direction of the tip, and the second local minimum is located between the first protrusion and the protrusion closest to the tip. As an alternative to the linear increase in the distribution of the maximum radius of the protrusion, the curve of the increase of the maximum radius of the protrusion towards the tip can also be decreasing, so as to adapt the groove opening performance and the hardness of the component material. The local minimum between these protrusions can correspond to the basic thread outer radius and can continue to decrease in the direction of the screw tip in the trench region extending at least partially beyond the screw tip, with the characteristic of a linear decrease. If the local minimum of the thread outer radius between these projections corresponds to the basic thread outer radius, the production of the screw is simplified and the pull-out force is increased, since the thread in the tip region of the thread profile can also contribute to the pull-out resistance. The thread is radially delimited by the thread tip. The thread generally extends along the thread helix with its thread tip, wherein the position of the point at the thread tip that defines the thread's outer radius varies with respect to an angle in the normal plane (plan view), which is called the wrap angle. The wrap angle is therefore the angle formed by the outer radius of the thread, perpendicular to the thread helix relative to the screw axis, and the starting perpendicular line defined at the free end of the screw, in particular at the beginning of the thread. Starting from the starting perpendicular line at the beginning of the thread, the wrap angle increases by 360° with each revolution. According to an ideal technical approach for the projection, at the first wrap angle of the projection, the thread outer radius can be equivalent to the basic thread outer radius. In this case, as the wrap angle increases, at the wrap angle position where the projection reaches its maximum value, the thread outer radius is equivalent to the maximum radius of the projection. As the wrap angle increases further, at the wrap angle position at the end of the projection, the thread outer radius is equivalent to the basic thread outer radius. This allows the thread outer radius to increase or decrease relative to the basic thread outer radius. This improves load-bearing capacity in areas where the basic thread outer radius still increases. According to an ideal development of the projection, the thread outer radius increases monotonically from the basic thread outer radius within the projection wrap angle and then decreases monotonically back to the basic thread outer radius. This allows for simple production of the projection and achieves defined groove characteristics. In particular, the increase and decrease occur along a parabola, the vertex of which is located at the maximum radius of the projection. The outer radius of the basic thread ideally increases linearly between two projections extending parabolically along the helical line in the direction of the head. According to another advantageous refinement of the present invention, the maximum radius of one preformed projection is greater than the outer radius of the next thread at the beginning of the next projection, in the direction of the screw head. At the beginning of the projection, the curve of the increasing outer radius of the thread has a steeper slope than the course of the basic thread. This arrangement of the projections ensures that any preformed projection only needs to provide trenching efficiency in a limited area, thereby reducing tapping torque and minimized wear on the projections. According to another advantageous refinement of the present invention, in a plane normal to the screw centerline, the projection wrap angle between the maximum radii of two adjacent projections corresponds to the angular distance alpha, where 360° / n-10° < alpha < 360° / n+10°, with n being between 2, 3, or 4, and the angular distance of the projections being less than 210° / n. This defines relatively short projections within this projection wrap angle, thereby reducing friction in the region of the maximum projection radius. This reduces the screw-in torque. These projections can not only extend outwards in the direction of the outer radius of the thread, but can also have an extension in the longitudinal direction of the screw which is greater than the extension of the basic thread in the longitudinal direction of the screw. In this way, the width of the nut thread can be gradually increased by the preformed protrusion. The length of the thread in the tip region is in particular less than five turns. Therefore, in particular when screwing into a blind hole, the majority of the screw length can play a supporting role. According to another advantageous development, the thread root diameter increases starting from the tip in the tip region until it corresponds to the thread root diameter in the support region. This improves the manufacturability of the screw according to the invention. The relative increase in thread root diameter may be smaller than the increase in basic thread radius. The ideal slope of the thread line is about 5°-7°, which corresponds to an increase of 3% to 5% in the outer radius of the basic thread per turn. In particular, when the maximum radius of the projection increases proportionally, the nut thread can be gradually formed into the nut material due to the small increase. The aforementioned screws are ideally made of steel. FIG1 is a perspective view of the front end of a screw 100 according to the invention, which has a cylindrical support area and a conical tip area. A Starting from the bearing region TB of the thread 200, the thread tapers continuously in the tip region SB, thereby forming a conical envelope curve. The thread profile of the thread 200 corresponds to the thread profile described in FIG. 5 . The thread profile described in conjunction with FIG. 5 , with the oval thread tip, particularly the tip region, reduces the tapping torque when screwing into pre-drilled or cored holes in components made of light metal materials, particularly aluminum. FIG2 a is a side view of a screw 10 according to the invention for screwing into a component made of light metal material. The screw 10 comprises a front end, referred to as the screw tip 12, and a head 18 at the other end of the screw 10. This screw has a thread 20 with a bearing region TB, wherein the thread 20 has a constant outer thread radius R within the helix. A , that is, the radius of the support area R T , which corresponds to half the outer diameter in the bearing area TB. Bearing area radius R T The ideal is based on the nominal outer diameter of the screw. Therefore, the bearing area radius R T The support area TB adjoins the tip area SB in the direction of the screw tip 12 , and the thread outer radius R of the thread 20 is A In this tip region, the thread 20 changes along the helical line and thus decreases to the screw tip 12. In the tip region SB, the thread 20 has circumferentially defined and radially extending projections 14.2, 14.5, 14.8, 16.1, 16.2 (also referred to as 14.X, 16.X). In the region of these projections 14.X, 16.X, the thread 20 has a varying outer thread radius R. A Starting from the screw tip 12, the thread outer radius R A The thread 20 is substantially enlarged and formed, and the thread substantially includes a basic thread outer radius R AB The basic thread, where the basic thread outer radius R AB In addition, this thread also has protrusions 14.X and 16.X, and the outer radius of the protrusion R AE Relative to the basic thread outer radius R AB Has increased. Of the local projections 14.X, 16.X in the tip region SB, at least two projections 16.X have a projection maximum radius R E10max 、R E11max This maximum radius of the projection is the same for both projections 16.1 and 16.2 and corresponds to the calibration radius R K , this calibration radius is larger than the support area radius R T These projections are referred to as calibration projections 16.X because, at least along the helix, the calibration projections 16.X that are further away toward the head do not require any additional forming work to produce the nut thread. Instead, they ensure that any errors that may exist in the preformed thread, particularly in the thread tip area, are reduced. In particular, these errors are to be reduced due to wear on the calibration projections 16.X that are closer toward the screw tip 12. This reduces the friction of the thread 20 in the bearing area TB that is subsequently screwed into the grooved thread, allowing the screw-in torque to be kept within a low range. For the purpose of thread forming, at least three pre-forming projections 14.X are arranged between the calibration projection 16.X and the frontmost tip 12, which pre-forming projections are formed with respect to their respective maximum projection radius R E1max ,...,R E9max The calibration radius R K In this embodiment, there are 9 preformed protrusions 14.X. E1max to R E9max , i.e. the outer thread radius RA at the local maximum of the projection 14.X increases in the direction of the support area TB in the tip area SB, so that the nut thread is formed into the nut material with an increasing depth. In particular, the maximum projection radius R can be clearly seen in the diagram shown in FIG3a. E1max In this figure, the corresponding maximum radius of the convexity R E1max to R E9max The increasing curve of AEmax To express. FIG2 b is a perspective view of the screw tip 12 of the screw 10 . Similar to the embodiment shown in FIG1 , the thread 20 starts from the screw tip 12 and extends along its spiral line toward the head. Starting from the starting point S on the thread 20, for example, from the beginning of the thread 20, the thread radius is at the angular position WP where the maximum radius of the second preformed protrusion 14.2 is located. E2maxWhen projected onto a normal plane relative to the screw's center axis MA, the angle at the thread's starting point forms a wrap angle U with the radius at the starting point. With each revolution, wrap angle U increases by 360°. As wrap angle U increases, the position of the thread's outer radius at the corresponding angular position shifts along the screw's center axis toward the head. A top view of the normal plane is shown in Figure 2c. In this example, the maximum value between two adjacent protrusions (for example, the angular position WP E2max With WP E3max The angular distance alpha between the maximum values ​​of two adjacent protrusions 14.X and 16.X is 120°. Therefore, unlike the embodiment shown in FIG2a , the axially stacked protrusions are not circumferentially offset relative to each other. Alternatively, the angular distance alpha between the maximum values ​​of two adjacent protrusions 14.X and 16.X can be 125°, for example. Thus, these protrusions are not circumferentially offset. Furthermore, each protrusion extends over a surrounding angular distance beta. Thus, each protrusion 14.X, 16.X has an angular position WP where the protrusion 14.X, 16.X begins and another angular position WP where the protrusion ends. The third protrusion 14.3 is, for example, at an angular position WP E3 開始 Starting at angular position WP E3 結束 It extends to the end of the third protrusion 14.3. The angular distance alpha between two adjacent protrusions is preferably at least twice the angular distance beta between the protrusions. FIG3 a schematically shows the direction of the thread line GL at the outermost point of the thread tip within the scope of the helix along its development within the wrap angle. As can be seen from the figure, in the tip area SB, the thread outer radius R A The large increase in the outer radius of the basic thread is shown as a basic thread line BL in a short dashed line. This short dashed line shows the course of the "basic thread", ie the course of the thread 20 without the local projections 14.X, 16.X. The solid line shows the course of the actual thread line GL along the basic thread in the region of these projections, which project beyond the basic thread line with respect to their thread outer radius. AEmax has its local maximum at . In this example, R AEmax The enlargement in the area of ​​the tip is parallel to the basic thread line. As can be seen from the figure, these protrusions are designed to be shorter along the circumferential direction and extend only within a shorter angular range not exceeding pi / 3 (60°). E2 結束 With WP E3 開始 The surrounding angular distance between them is approximately pi / 3 (60°). The thread is formed in the tip region SB of the screw 10, ie in the outer thread radius R of the basic thread. A In the continuously increasing (in this example linearly increasing) area, there are three calibration protrusions 16 .X. The three calibration protrusions 16.X have the same protrusion maximum radius R E10max 、R E11max 、R E12max , which is equivalent to the calibration radius R K Calibration radius R of calibration protrusion 16.X K And the corresponding maximum radius R of the convex E10max 、R E11max 、R E12max Greater than the supporting thread radius R of the thread in the screw supporting area TB T . Since the calibration projection 16.X is located in the area of ​​increased radius in the tip region SB, the basic thread radius R is larger than that in the support region TB. AB With calibration radius R K The difference between them is large. This allows the calibration projection 16.X to be reliably manufactured with sufficient precision using a rolling process. This allows the tapping torque of this screw to be reduced more reliably when screwing directly into light metal. The circumferential extension of projection is roughly equivalent to or ideally less than 60 ° of surrounding angle distance. Accordingly, only in smaller helical angle, cause friction, thereby can make screwing-in torque remain smaller. FIG3b is a partial enlargement of the diagram shown in FIG3a, focusing on the calibration projection 16.X. In this enlarged view, it is clearly seen that even for the projection closest to the support area TB, the difference in thread outer radius from the basic thread BL is still much greater than the difference in outer radius in the support area TB, in which the difference is only R K -R T And according to the present invention, it is ideally less than 0.1 mm. In this way, the calibration projection 16 .X can be produced more precisely using a rolling process according to the technical principle of the invention, in order to achieve the most precise possible design of the nut thread. Between the calibration projection 16.3 closest to the support area and this support area, the surrounding angular position WP E12 結束 Thread outer radius R at A The thread outer radius R has a local minimum A (WP E12 結束 ). The thread outer radius R at this local minimum A (WP E12 結束 ) and the support area radius R T The ratio is ideally less than 0.996. Furthermore, at the end of the second calibration projection 16.2, ie at the wrap-around angle position WP E11 結束 At this point, another local minimum thread outer radius R is generated A (WP E11 結束 ). The thread is designed in such a way that the calibration radius R K Percentage exceeding the minimum mean value versus calibration radius R K Beyond the support area radius R T The percentage ratio is greater than 1.4. The minimum average value is the thread outer radius R at the first local minimum A (WP E12 結束 ) and the thread outer radius R at the second local minimum A (WP E11 結束 ) is the average value of . Therefore, the design of the thread satisfies the following formula: ((R K / ((R A (WP E12 結束 ) + R A (WP E11 結束 )) / 2)) – 1) / ((R K / R T )-1) > 1.4 FIG. 4 shows the extension of the projections in the axial direction. FIG4 shows a schematic cross-sectional view AA of the thread 20 at the transition from the bearing region TB to the tip region SB. Starting from its thread base GG, in the region of the calibration projection, the thread 20 has a thread flank facing the head (i.e., load flank 52), which merges with a thread tip 54 having an elliptical profile. The thread tip 54 then merges again with a thread flank (i.e., guide flank 56) toward the screw tip. The outline of the basic thread is indicated by a dashed line; this basic thread would be present in the section plane if there were no projection. In this case, the actual course in the bearing region TB corresponds to that of the basic thread, which has a load flank 42, a thread tip 44, and a guide flank 46. The calibrating projection 54 protrudes beyond the course of the basic thread to a limited extent in the circumferential direction. The calibrating projection has a projection maximum radius R at its local maximum. AEmax , which in this example corresponds to the calibration radius R KAs shown in FIG. 4 , in contrast to the basic thread shown in dashed form, this projection also extends axially beyond the basic thread, wherein this projection is ideally rolled in during the rolling process. It can also be seen from Figure 3b that at the angular position WP11 AEmax In the area where the basic thread height is still increased, the basic thread and the calibration height R K The difference between them is much larger than the difference between the support area TB and the support area radius R T In this way, the protrusion 54 can be manufactured more reliably. This basic thread has an oval thread tip 44 in the bearing area. This thread tip design is illustrated in detail in FIG. The thread tip 54 has an elliptical cross section, and its design and effect will be described in detail with reference to FIG. 6 . Due to the increased resistance to wear of the oval thread tip, in combination with the design according to the invention of the calibration region in the tip region, a particularly reliable and precise shaping of the nut thread is possible. The elliptical profile of the thread tip in the bearing area is particularly suitable for adapting to the cross-sectional shape of the projection, thereby increasing the contact surface in the tightened state, which in turn can increase the extraction force. The shape of this raised thread tip is similar to that of the basic thread, which will be explained in detail below with reference to Figure 6. FIG5 shows a thread profile as a cross-section of the thread in the bearing region TB, as may be found in the screw designs shown in FIG1 , FIG2a , or FIG2b . This thread profile has a thread tip 44 with an oval cross-section. This thread shape is also generally present in the basic thread in the screw tip region SB. If projections are provided in the tip region, this thread shape also exists in the thread region between the projections. The cross-sectional profile of the thread tip 44 is an ellipse SE. The thread tip 44 connects with the guide flank 46 toward the screw tip and with the load flank 42 toward the screw head. The vertex SP of the thread tip is located at the vertex of the ellipse SE at the intersection with its semi-major axis HA. The thread tip 44 meets the load flank 42 at a transition point UP1 and meets the guide flank 46 at a transition point UP2. The transition points UP1 and UP2 are the points where the thread profile leaves the elliptical path SE defining the thread tip 44. At the transition points UP1 and UP2 , tangent lines T1 , T2 , respectively, defining the flank angles, may be applied. A tangent line T1 , which forms a load flank angle LF with the semi-major axis HA, abuts the transition point UP1 . The perpendicular line to the tangent line T1 at the transition point UP1 intersects the semi-major axis at the intersection point BP1. The thread tip is ideally designed so that the distance between the intersection point BP1 and the transition point UP1 is less than 90% of the distance between the vertex SP and the intersection point BP1. This achieves sufficient curvature at the thread tip for good material flow during displacement, thereby reducing wear on the thread tip during the trenching process. Furthermore, the thread tip is ideally shaped in such a way that a line VL1 connecting the transition point UP1 and the vertex SP forms an angle VL1-HA with the semi-major axis HA. The angle VL1-HA is particularly smaller than 45°, and in this embodiment is approximately 35°. The thread tip 44 is designed in such a way that what applies to UP1 also applies to the leading edge UP2. The tangent line T2 is located at the transition point UP2, which intersects the leading edge angle FF of the semi-major axis HA. The perpendicular line to the tangent line T2 at transition point UP2 intersects the semi-major axis at intersection point BP2. Ideally, the thread tip should be designed so that the distance between transition point BP2 and transition point UP2 is less than 90% of the distance between vertex SP and intersection point BP2. This ensures sufficient curvature at the thread tip, allowing for smooth material flow during displacement and reducing wear on the thread tip during the grooving process. Furthermore, the shape of the thread tip is ideally such that a line VL2 connecting the transition point UP2 and the vertex SP forms a vertex angle VL1-HA with the semi-major axis HA. The vertex angle VL1-HA is preferably less than 45°, and is approximately 25° in this embodiment. Furthermore, a basic flank angle can also be determined, which results from the sum of the load flank angle LF and the guide flank angle FF. In the present embodiment, this basic flank angle is 35°. The thread is ideally designed in such a way that a line parallel to the tangent line T1 passing through the apex intersects the thread base line at the perpendicular FP1. According to the present invention, the distance A1 of the perpendicular FP1 from the semi-major axis is at most three times the distance A2 of the transition point UP1 from the semi-major axis. In the embodiment described, the thread is designed in such a way that the distance A1 is approximately twice the distance A2 from the transition point to the semi-major axis HA. This allows for an elongated thread shape. In this embodiment, the side curves of the guide flank 46 and the load flank 42 are at least partially defined by elliptical profiles. The eccentricity of these side ellipses FE1 and FE2 is much smaller than the ellipse SE defining the thread tip. FIG6 shows a thread cross section of another thread shape in the tip region SB of screw 10, wherein the thread tip 54 of the trenching region is shown in the region of the projection. The oval thread tip 54 contributes to improved trenching properties, thereby reducing wear on the thus designed calibration projection. Furthermore, the projection profile is opposite the thread cross section of the basic thread with the thread tip 34, as would be present at the intersection of the thread and the projection if the basic thread were to extend uniformly and continuously. The vertex SP is located here at the maximum radius of the projection of the projection facing away from the center axis of the screw. The orientation of the tip ellipse is similar to the orientation of the tip ellipse shown in Figure 5. Because the thread has the same profile as the basic thread in the bearing region, the tangent T1 to the ellipse defining the thread tip at the transition point UP1 in the raised region in the bearing region TB is parallel to the tangent T1 to the ellipse at the transition to the load flank in the bearing region TB. Consequently, these two tangents form the same load flank angle with the semi-major axis HA. The same approach applies to the tangent T2 as described above with respect to the guide flank. In this respect, the cross-sectional profile of the projection essentially corresponds to the profile of the support region. In this projection, only the region where the thread flanks follow the tangent lines T1, T2 is longer. This results in a pre-grooving of the thread, which is enlarged relative to the support region, with which the thread in the support region can engage via the flank regions of the nut thread that are parallel to the pre-grooved region. The calibration projection closest to the support area is also designed in this way, but the difference between the basic thread and the projection is greater than the difference between the thread and the projection in the support area. This ensures that the projection can be produced reliably, while still producing a preformed nut thread that is only slightly larger. 10,100: Screw 20,200: Thread TB: Bearing area SB: Tip area 14.X, 14.2, 14.5, 14.8: Protrusion 14.3: Third protrusion 16.X: Calibration protrusion (protrusion) 16.1: Protrusion 16.2: Second calibration protrusion (second protrusion, protrusion) 16.3: First calibration protrusion (calibration protrusion) 12: Screw tip R A :Thread outer radius R AB : Basic thread outer radius (basic thread radius) R AE : Protrusion outer radius 18: Screw head MA: Screw center axis R T : Support area radius alpha: Wrap angle distance U: Wrap angle WP E2 ,WP E3 :Angular position WP E2max ,WP E3max : Angle position S where the maximum radius of the protrusion is located: Starting point beta: Surrounding angular distance R K :Calibration radius R AEmax ,R E8max ,R E2max : Maximum radius of the protrusion GG: Thread baseline BL: Basic thread line (basic thread) GL: Thread line WP E11 ,WP E12 : Wrap angle position 42, 52: Load side 44, 54: Thread tip 46, 56: Guide side AA: Sectional view T1, T2: Tangent FP1: Perpendicular foot A1, A2: Distance HA: Semi-major axis SE: Ellipse SP: Vertex BP1, BP2: Intersection point FE1, FE2: Side ellipse UP1, UP2: Transition point VL1-HA, VL2-HA: Vertex angle 34: Thread tip For other advantages, features and application means of the present invention, please refer to the following description in conjunction with the embodiments shown in the drawings. 1 is a perspective view of the front end of a screw according to the invention; FIG2a is a side view of the screw in the support area and the tip area; FIG2b is a perspective view; FIG2c is a top view of the tip; FIG3a is a diagram of the thread line and the (interpolated) thread root diameter; FIG3b is a partial enlarged view of FIG3a; FIG4 is a partial sectional view of the thread; FIG5 is a cross-sectional view of the profile curve of the support thread; and FIG6 is a cross-sectional view of the thread profile curve of the calibration protrusion. T1, T2: tangent FP1: Vertical foot A1, A2: distance HA: semi-major axis SE: Ellipse SP:Vertex BP1, BP2: intersection point FE1, FE2: Side ellipse UP1, UP2: Transition Points VL1-HA, VL2-HA: Vertex Angle 42: Load side 44: thread tip 46: Guide side

Claims

1. A screw (10) for direct screwing into a component, the component being made of a light metal material, the screw comprising: The head and shank, wherein the shank is provided with a thread (20) having an outer radius (RA) that decreases toward the screw tip (12) from a cylindrical support region (TB) having a constant support region radius (RT) within a tip region (SB). The thread (20) has guide sides (46, 56) toward the screw tip (12) and load sides (42, 52) toward the head (18), wherein the guide sides (46, 56) and the load sides (42, 52) are connected by thread tips (44, 54), wherein the profile of the thread tips (44, 54) from the guide sides (46, 56) to the load sides (42, 52) follows an elliptical path along an ellipse (SE) defining the thread tips, wherein the vertex (SP) of the semi-major axis of the ellipse (SE) is located in the thread tips, and the ellipse (SE) has a connection with the load sides (42, 52). The transition points (UP1, UP2) and the transition points (UP1, UP2) with the guide sides (46, 56) form a load side angle (LF) with the tangent (T1) of the ellipse and the semi-major axis (HA) of the ellipse (SE) at the transition points (UP1, UP2) with the load sides (42, 52), and a guide side angle (FF) with the tangent (T2) of the ellipse (SE) and the semi-major axis (HA) of the ellipse at the transition points (UP1, UP2). The thread tip is designed such that an orthogonal line orthogonal to the tangent (T1, T2) at the transition points (UP1, UP2) intersects the semi-major axis (HA) at the intersection point (BP1; BP2). The characteristic is that the distance between the intersection point (BP1; BP2) and the transition point (UP1, UP2) is less than 90% of the distance between the vertex (SP) and the intersection point (BP1; BP2).

2. The screw as described in claim 1, wherein, The distance between the transition point (UP1) with the load side (42, 52) and the semi-major axis (HA) is greater than 1 / 3 * thread height * tan (load side angle), and the distance between the transition point (UP2) with the guide side (46, 56) and the semi-major axis (HA) is greater than 1 / 3 * thread height * tan (guide side angle).

3. The screw as described in claim 1 or 2, wherein, The line connecting the transition point (UP1; UP2) to the vertex (SP) of the semi-major axis (HA) at the tip of the thread (VL1; VL2) forms a vertex angle (VL1-HA, VL2-HA) of less than 55° with the semi-major axis (HA).

4. The screw as described in claim 1, wherein, The load side angle (LF) and the guide side angle (FF) are at most 30°.

5. The screw as described in claim 1, wherein, The elliptical thread tip (34, 44) extends tangentially to the transition portion of the thread side; the thread side includes the load side (42, 52) and the guide side (46, 56).

6. The screw as described in claim 5, wherein, The guide side (46, 56) and / or the load side (42, 52) extend along an elliptical path that bends in the opposite direction to the ellipse (SE) that forms the thread tip (44, 54).

7. The screw as described in claim 1, wherein, The guide side (46, 56) and / or the load side (42, 52) extend along an elliptical path from the corresponding transition point (UP1, UP2), the elliptical path being curved in the opposite direction to the ellipse (SE) forming the thread tip (44, 54).

8. The screw as described in claim 6, wherein, The numerical eccentricity of the elliptical path of the guide side (46, 56) and / or the load side (42, 52) is less than the numerical eccentricity of the ellipse defining the thread tip.

9. The screw as described in claim 1, wherein, The semi-major axis (HA) of the ellipse (SE) defining the thread tip is inclined toward the guide side (46, 56) at an angle not exceeding 10° relative to the normal plane about the screw centerline.

10. The screw as described in claim 1, wherein, The spacing between adjacent thread flanks at 90% of the thread height is greater than 0.7 times the lead, and at that point, the flank width is less than 0.5 times the thread height.

11. The screw as described in claim 1, wherein, The thread (20) has at least five circumferentially restricted, radially extending protrusions (14.X, 16.X) in the tip region (SB), wherein in the region of the protrusions (14.X, 16.X), the thread outer radius (RA) has a corresponding maximum protrusion radius (RE1max, RE2max, ..., RE9max), wherein at least two protrusions are calibration protrusions (16.X), and the maximum protrusion radius (RE10max, RE11max, RE12max) of the calibration protrusions (16.X) is... x) are of the same size and are equivalent to the calibration radius (RK), which is greater than the support area radius (RT), wherein at least three preformed protrusions (14.X) are arranged between the calibration protrusion (16.X) and the foremost screw tip (12), the corresponding maximum protrusion radius (RAEmax) of the preformed protrusion is smaller than the maximum protrusion radius (RAEmax) of the calibration protrusion (16.X), and the maximum protrusion radius (RAEmax) of the preformed protrusion (14.X) decreases toward the screw tip (12).

12. The screw as described in claim 11, wherein, There exists a first local minimum of the thread outer radius (RA) between the support area radius (RT) and the first calibration protrusion (16.3), which is smaller than the support area radius (RT).

13. The screw as described in claim 12, wherein, The ratio of the outer radius of the thread at the first local minimum (RA(WPE12 end)) to the radius of the support area (RT) is less than 0.

996.

14. The screw as described in claim 12 or 13, wherein, The thread is designed such that the percentage by which the calibration radius (RK) exceeds the minimum average value ((RA(WPE12 end) + RA(WPE11 end)) / 2) is greater than 1.4 of the percentage by which the calibration radius (RK) exceeds the radius (RT) of the support area. The minimum average value is composed of the average of the thread outer radius (RA(WPE12 end)) at the first local minimum value between the support area and the first calibration protrusion (16.3) and the thread outer radius (RA(WPE11 end)) at the second local minimum value between the first calibration protrusion (16.3) and the second calibration protrusion (16.2).

15. The screw as described in claim 14, wherein, Starting from the tip (12), within the area of ​​the tip region, the increase of the corresponding maximum radius (RAEmax) of the preformed protrusion (14.X) is consistent with the increase of the outer radius (RA) of the thread at the local minimum between the preformed protrusions (14.X).

16. The screw as described in claim 11, wherein, The maximum radius (RAEmax) of the preformed protrusion (14.X) increases from the tip of the screw, and the rate of increase decreases.

17. The screw as described in claim 11, wherein, In the protrusions (14.X, 16.X), at the first surrounding angle position (WPEX start) of the surrounding angle (U), the thread outer radius (RA) is at the level of the basic thread outer radius (RAB). In the case of further increase, the thread outer radius (RA) is equivalent to the maximum radius (RAEmax) of the protrusion. In the case of further increase, at the surrounding angle position (WPEX end) of the surrounding angle (U) at the end of the protrusion, the thread outer radius is equivalent to the basic thread outer radius (RAB).

18. The screw as described in claim 17, wherein, In the protrusions (14.X, 16.X), the outer radius of the thread (RA) increases continuously within the surrounding angle distance (beta) from the basic outer radius of the thread (RAB) and then decreases until it is again equivalent to the basic outer radius of the thread (RAB), following a parabolic trajectory.

19. The screw as described in claim 17, wherein, In the thread (20) between two adjacent preformed protrusions (14.X), the basic thread outer radius (RAB) increases linearly from the screw tip.

20. The screw as described in claim 11, wherein, The radius of the support area (RT) is greater than 90% of the calibration radius (RK).

21. The screw as described in claim 11, wherein, The calibration radius (RK) is at most 0.1 mm larger than the support area radius (RT).

22. The screw as described in claim 11, wherein, The maximum radius of a preformed protrusion (RAEmax) is greater than the outer radius of the next thread at the beginning of the next protrusion in the direction toward the head (18).

23. The screw as described in claim 11, wherein, The surrounding angle (U) between the maximum values ​​of two adjacent protrusions in the normal plane relative to the screw's central axis is equivalent to the surrounding angle distance (alpha), where 360° / n - 10° < alpha < 360° / n + 10°, where n is between 2, 3, or 4, and the angular distance (beta) of the protrusions is less than 210° / n.

24. The screw as described in claim 11, wherein, The protrusions (14.X, 16.X) also extend axially on both sides across the basic thread.

25. The screw as described in claim 11, wherein, The length of the thread (20) within the tip region (SB) is less than five turns.

26. The screw as described in claim 11, wherein, The slope of the thread is approximately 5°-7°, which is equivalent to an increase of 3% to 5% in the outer radius of the basic thread per turn.

27. The screw as described in claim 11, wherein, The root diameter (DK) of the thread increases within the tip region (SB) starting from the tip (12).

28. The screw as described in claim 27, wherein, Starting from the tip (12) of the screw and moving towards the head, the relative increase in the root diameter (DK) of the thread is less than the increase in the outer radius (RAB) of the basic thread.

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