Screw for direct screwing into component
By designing multiple projections in the screw tip area and building calibration projections, the problem of difficulty in creating calibration projections in the prior art is solved, and higher fixation performance and smaller screwing torque are achieved.
Patent Information
- Application Number
- CN202380061396.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-08-24
- Filing Date
- 2023-08-23
- Publication Date
- 2025-05-06
AI Technical Summary
The existing self-tapping screws are difficult to reliably manufacture calibrated protrusions in the rolling process, which makes it difficult to take into account both the fixing performance and the manufacturing properties, and the screwing torque is relatively large.
A screw is designed with the tip region having at least five radially extending protrusions by which nut threads are generated in the nut material of the member, threads in the supporting region are screwed into the member. At least two projections are constructed as calibration projections for improving fixation performance and reducing screw-in torque.
By reducing the screwing torque and improving the fixing performance of the screw, the screw manufacturing process is simplified, ensuring a defined structure of calibration projections and suitable for components made of light metal materials.
Smart Images
Figure CN119948266A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a screw for direct screwing into a component, in particular a component made of light metal material. Background Art
[0002] EP 1 053 405 B1 discloses a self-drilling screw having a retaining section and a penetration section, by means of which the thread displaces the nut material to form the thread. The end of the penetration section facing the screw head forms a calibration section, which penetrates only slightly into the nut part and is to calibrate the formed thread. In this area, the minimum height between the calibration projections is the same as the thread radius in the cylindrical support area. These calibration projections form two opposite support points, which are at the same distance from the center axis of the screw. They should protrude slightly beyond the support diameter only.
[0003] A similar design is known from WO 95 / 14863 A1, which describes a self-tapping screw having a forming element placed on the thread line. This screw is intended to reduce the screw-in torque which, in principle, increases with increasing screw-in depth during thread forming in the nut material.
[0004] This screw has a profiled area in the front region, which extends radially beyond the basic thread which is essentially continuous from the shank to the tip, which is limited in the circumferential direction and is relatively short. The screw has a calibration projection in the bearing region, which protrudes only slightly beyond the bearing thread, in particular less than 0.08 mm.
[0005] The aforementioned screws reduce friction during the trenching process and at the same time still achieve good fixing properties. It is difficult to reliably produce such calibration projections, especially by rolling processes, because the material required to form the calibration projections is not sufficiently available during the rolling process. Therefore, a defined structure of the calibration projection cannot be reliably ensured. Summary of the invention
[0006] Therefore, the object of the present invention is to further improve the fixing performance of the screw and simplify the manufacturability thereof while keeping the tapping torque low.
[0007] The solution of the invention for achieving the above-mentioned object lies in the features of claim 1 and its preamble.
[0008] In a known manner, a screw for direct screwing into a component, in particular a component made of light metal material, comprises a head with a driver and a shank, wherein the shank is provided with a thread. The thread outer radius of the thread decreases from a cylindrical bearing area in the region of a tip area toward the screw tip, so that the thread outer radius at the end of the thread at a distance from the head is smaller than the thread outer radius in the bearing area. The tip area begins at the point of the screw closest to the bearing area and extends to the screw tip, at which point the thread outer radius is smaller than the bearing area radius.
[0009] The nut thread is produced by the thread in the tip region in the nut material of the component into which the thread in the support region is screwed.
[0010] The thread has at least five radially extending projections in the tip region. These projections are limited in the circumferential direction. This means that there are local minima between the projections.
[0011] The thread outer radius locally follows the basic thread course along the helix. This basic thread course is interpolated via the local minima in the tip region, which are located between the projections. In the region where the thread follows the interpolated basic thread course, the thread is referred to as a basic thread, which has a basic thread outer radius that increases in radius from the screw tip to the bearing region.
[0012] 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 preferably decreases strictly monotonically, in particular linearly, in the tip region and corresponds to the bearing region radius in the bearing region.
[0013] 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 region in which the thread of the bearing region meshes with the thread pre-grooved in the tip region by the projections. Thus, according to the invention, projections are no longer provided in the cylindrical part of the external thread, since these projections would have a negative impact on the screw-in properties because they cannot be reliably produced in this region.
[0014] In the tip region, the thread has in the region of these projections a thread outer radius which is modified compared to the basic thread outer radius and which is correspondingly increased relative to the basic thread outer radius. Thus, each projection has a maximum thread outer radius in the circumferential direction along the helix which corresponds to the maximum radius of the projection corresponding to the projection. This ensures that the thread outer radius increases or decreases along the helix within the region of this projection.
[0015] According to the invention, at least two projections are designed as calibration projections, wherein the projection maximum radius of the calibration projections is of the same size and is at the same time greater than the support area radius. The projection maximum radius of the calibration projections defines the calibration radius.
[0016] By means of at least two calibration projections, only the calibration projection closest to the screw tip provides a trenching efficiency. At least one calibration projection spaced further away provides no or only a significantly reduced trenching efficiency until the calibration projection closer in the direction of the screw tip wears out. In this case, the subsequent calibration projection in the direction of the support area assumes the trenching function until the calibration projection closer in the direction of the screw tip wears out. As a result, the support thread can engage with the preformed thread in the component, which is preformed in a largely defined manner, due to a longer screw-in stroke and the associated higher trenching efficiency. This reduces the screw-in torque.
[0017] 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 is only achieved when the calibration projection near the screw tip is worn.
[0018] The calibration projections are located in a region where the outer radius of the basic thread is reduced, so that the difference to the outer radius of the basic thread is greater than the radius of the bearing region. Even if the difference between the calibration radius (i.e. the maximum projection radius of the calibration projection) and the radius of the bearing region is small, these calibration projections can be manufactured more reliably, because material for forming the calibration projections is thus available. The difference between the maximum projection radius of the calibration projection (i.e. the calibration radius) and the radius of the bearing region is preferably very small, in particular less than 0.1 mm.
[0019] Preferably, at least three calibration projections with the same maximum projection radius can be provided. Thus, there is one calibration projection closest to the screw tip which still provides a lower trenching efficiency and two further calibration projections which are arranged further away from the screw tip. After the calibration projection closest to the screw tip has worn out, the thread line in the component can be precisely formed by the calibration projections which are further apart. This design is more advantageous the higher the hardness of the component material and the nut material.
[0020] Furthermore, at least three preformed protrusions are arranged between the calibration protrusion and the frontmost screw tip, the respective protrusion maximum radius of which is smaller than the protrusion maximum radius of the calibration protrusion, i.e. the calibration radius. Furthermore, the protrusion maximum radius of the respective preformed protrusion decreases in the direction of the screw tip. This allows the nut material to be formed gradually. In this case, the difference in the protrusion maximum radius of successive protrusions is preferably selected in such a way that each preformed protrusion must provide approximately the same trenching efficiency.
[0021] According to a preferred technical solution, the basic thread outer radius increases from the screw tip in the tip region in the same way as the maximum radius of the preformed protrusion increases. The interpolation curve of the maximum radius of the protrusion is particularly parallel to the interpolation curve of the local minimum.
[0022] Preferably, there is a local minimum of the outer thread radius between the radius of the bearing region and the maximum radius of the first projection in the direction of the screw tip, at which the outer thread radius is smaller than the bearing region radius. This means that the projection in front of the bearing region in the direction of the head also drops to the level of the basic thread, which has a smaller thread outer diameter than the bearing region radius at this point. As a result, the first projection from the bearing region in the direction of the screw tip is completely located in the tip region.
[0023] The ratio of the thread outer radius at the first local minimum to the bearing region radius is preferably less than 0.996. This achieves a sufficiently large difference in the thread outer radius to provide sufficient material to form the projection.
[0024] According to another advantageous solution, the 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.
[0025] The minimum average value is the average value 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.
[0026] As an alternative to a linear increase in the distribution of the maximum radius of the protrusion, the curve of the increase of the maximum radius of the protrusion in the direction of the tip can also be decreasing, so that the trenching performance and the hardness of the component material can be adapted.
[0027] The local minima between these projections can correspond to the basic thread outer radius and can decrease continuously 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.
[0028] If the local minimum of the thread outer radius between these projections corresponds to the basic thread outer radius, this simplifies the production of the screw and increases the pull-out force, since the thread in the tip region of the thread profile can also contribute to the pull-out resistance.
[0029] The thread is delimited radially by the thread tip. The thread usually extends along the thread helix with its thread tip, wherein the position of the point at the thread tip that determines the outer thread radius varies with respect to its angle in the normal plane (plan view), which is called the wrap angle.
[0030] Thus, this wrap angle represents the angle formed by the outer thread radius relative to the orthogonal line of the thread helix that is orthogonal to the screw axis and the starting orthogonal line defined at the free end of the screw, particularly at the start of the thread. Starting from the starting orthogonal line at the start of the thread, this wrap angle increases by 360° per full turn.
[0031] According to a preferred embodiment of the protrusion, at the first wrap angle position of the protrusion wrap angle, the outer thread radius can correspond to the basic outer thread radius. In this case, as the wrap angle increases, at the wrap angle position at the maximum of the protrusion, this outer thread radius corresponds to the maximum radius of the protrusion. As the wrap angle further increases, at the wrap angle position at the end of the protrusion, this outer thread radius corresponds to the basic outer thread radius. Thus, an increase and decrease of the outer thread radius to the basic outer thread radius are achieved. This enables an increase in the load-bearing capacity in the region where the basic outer thread radius still increases somewhat.
[0032] According to a preferred refinement of the protrusion, the outer thread radius monotonically increases within the protrusion wrap angle starting from the basic outer thread radius and then monotonically decreases back to the basic outer thread radius. This enables simple production of the protrusion and achievement of defined grooving characteristics. In particular, the increase and decrease are achieved along a parabola, the vertex of which is located at the maximum radius of the protrusion.
[0033] The basic outer thread radius preferably increases linearly in the direction of the head between two protrusions that extend in a parabolic manner along the helix.
[0034] According to another advantageous refinement of the invention, the maximum radius of a preformed protrusion is greater than the next outer thread radius at the start of the next protrusion in the direction towards the screw head. At the start of the protrusion, the curve of the increase in the outer thread radius has a greater slope compared to the course of the basic thread. Through this layout of the protrusions, it is ensured that all preformed protrusions only need to provide grooving efficiency in a partial region, thereby reducing the tapping torque and reducing wear of the protrusions.
[0035] According to another advantageous refinement of the invention, in the normal plane relative to the screw central axis, the protrusion wrap angle between two adjacent maximum radii of the protrusions corresponds to the angular distance alpha, where 360° / n - 10° < alpha < 360° / n + 10°, where n is between 2, 3 or 4, and the angular distance of the protrusions is less than 210° / n. This defines relatively short protrusions within this protrusion wrap angle, thereby reducing friction in the region of the maximum radius of the protrusions. This enables a reduction in the screwing-in torque.
[0036] These projections can not only extend outwards in the direction of the outer radius, 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. This is especially true on both sides.
[0037] In this way, the width of the nut thread can also be gradually increased by the preformed projection.
[0038] 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.
[0039] 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 makes it possible to improve the manufacturability of the screw according to the invention.
[0040] The relative increase in thread root diameter may be smaller than the increase in basic thread radius.
[0041] The slope of the thread line is preferably about 5°-7°, which is equivalent to an increase of 3% to 5% per turn of the basic thread outer radius. 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.
[0042] In another advantageous refinement, the thread flank width is designed to be narrower in the axial direction. The thread has a guide flank facing the screw tip and a load flank facing the screw head. The guide flank forms a basic flank angle with the load flank. This basic flank angle is preferably between 25° and 45°. This can improve the screw-in performance, especially in high-strength light metal materials.
[0043] It is further preferred that the cross-section of the projections of the thread in the region of the screw tip is designed in such a way that the projections are oval in shape at the thread tip.
[0044] According to a particularly preferred technical solution, in the region of the projection, the guide side and the load side are connected by a thread tip, the contour of which is elliptical in cross section. In this case, the numerical eccentricity Epsilon of this ellipse is between 0.5 and 1.
[0045] Due to the oval design of the thread tip in the area of the projection, a strong shape can be provided at the outermost thread tip, so that this thread tip has good trenching properties. In addition, as the distance from the tip increases from the outermost thread tip to the flank increases in the direction of the thread root, the displaced material encounters less and less resistance. This reduces the radial forces required to deform the nut material, so that the thread can penetrate into the nut material more easily. This also reduces the wear of the projection, especially with regard to the calibration projection, which means that the definition of the thread in the nut material is improved.
[0046] In addition to the elliptical design of these raised thread tips, the thread tip of the basic thread in the bearing region can also have an elliptical shape. By adapting the shape of the basic thread in the bearing region, the contact of the basic thread with the grooved nut thread can be improved. According to a particularly preferred development, the thread is designed in such a way that two tangents intersect at the ellipse defining the thread tip and form an intersection angle, i.e. a basic flank angle of less than 60°, in particular less than 45°.
[0047] Each of the two tangents is at a contact point on the ellipse, which is located at the transition from the elliptical area defining the thread tip to the thread side surfaces adjacent to the thread tip (i.e., the load side surface and the guide side surface), wherein each tangent forms a half-side surface angle with the major semi-axis.
[0048] The distance between the two contact points and the semi-major axis is accordingly greater than 1 / 3*tan(half flank angle)*thread height. This thread height is the difference between the basic thread outer radius and half the thread root diameter. This design allows for a relatively narrow design of the thread flanks.
[0049] Further preferably, the thread tip can be further modified in the region of the protrusion in such a way that a line connecting the corresponding contact point and the vertex of the semi-major axis at the thread tip forms a vertex angle with this semi-major axis of less than 55°. This ensures that the thread tip extends correspondingly slender, so that the penetration performance into the nut material can be improved.
[0050] This results in a contact point on the load side and a contact point on the guide side. A perpendicular line through the contact point, which is perpendicular to the corresponding tangent line, intersects the semi-major axis at the intersection point. The thread tip can preferably be designed in such a way that the distance between the contact point and the intersection point is smaller than the distance from the intersection point to the apex of the thread tip. The distance between the contact point and the intersection point is preferably smaller than 90% of the distance from the intersection point to the apex of the thread tip.
[0051] According to a particularly preferred technical solution, the transition from the elliptical thread tip to the thread flank extends tangentially. Therefore, this transition is smoother, and the material displaced by the thread tip can flow further along the thread flank with low friction, thereby reducing the tapping torque.
[0052] This ellipse can preferably adjoin a straight section of the guide side and / or the load side, wherein the guide side and / or the load side coincides with the tangent.
[0053] In a further development of the invention, the guide flank and / or the load flank can extend along an elliptical path, the curvature of which is configured in a manner that is oriented in the opposite direction to the elliptical curvature at the thread tip. In this case, this curvature can be a straight section adjacent to the thread tip or the guide flank and / or the load flank.
[0054] The eccentricity of the elliptical path of the guide flank and / or the load flank is preferably smaller than the eccentricity of the ellipse defining the thread tip. This achieves a significant widening of the thread in the direction of the thread root, thereby increasing the shear strength and stability of the thread.
[0055] According to a further 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.
[0056] The spacing between adjacent thread flanks at 90% of their thread height is in particular greater than 0.7 times the lead. In addition, at 90% of their thread height, the flank width can be less than 0.5 times the thread height. This provides a sufficiently small thread tip width.
[0057] The screw is preferably made of steel. BRIEF DESCRIPTION OF THE DRAWINGS
[0058] For other advantages, features and application solutions of the present invention, please refer to the following description in conjunction with the embodiments shown in the accompanying drawings.
[0059] in:
[0060] Figure 1 is a side view of the screw in the bearing area and the tip area;
[0061] Figure 2a For perspective
[0062] Figure 2b is a top view of the tip;
[0063] Figure 3a It is a diagram of the thread line and the (interpolated) thread root diameter;
[0064] Figure 3b for Figure 3a A partial enlarged view of
[0065] Figure 4 It is a partial cross-sectional view of the thread;
[0066] Figure 5 A cross-sectional view of the profile curve of the supporting thread; and
[0067] Figure 6 Cross-sectional view of the thread profile curve for the calibration protrusion. DETAILED DESCRIPTION
[0068] Figure 1 1 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 in the bearing region TB the thread 20 has a constant thread outer radius R within the range of the helix. A , that is, the radius of the support area R T , which corresponds to half of the outer diameter in the bearing area TB. T It is preferably based on the nominal outer diameter of the screw. Therefore, the bearing area radius R T The support region TB adjoins the tip region 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 helical line changes and thus decreases to the screw tip 12. In the tip region SB, the thread 20 has circumferentially delimited 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 changing thread outer 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, the thread also has protrusions 14.X and 16.X, and the outer radius R of the protrusions is AE Relative to the basic thread outer radius R AB Has increased.
[0069] Of the local protrusions 14.X, 16.X in the tip region SB, at least two protrusions 16.X have a protrusion maximum radius R E9max , R E10max , this maximum radius of the projection is the same for both projections 16.1, 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, since at least the calibration projections 16.X which are further away along the helix in the direction of the head do not require any more forming work to produce the nut thread, but should ensure that any errors that may exist in the preformed thread, especially in the area of the thread tip, are reduced. In particular, such errors due to wear of the calibration projections 16.X which are respectively approaching in the direction of the screw tip 12, should be reduced. In this way, the friction of the thread 20 of the bearing area TB which is subsequently screwed into the grooved thread can be reduced, so that the screw-in torque can be kept within a small range.
[0070] For the purpose of thread forming, at least three preforming projections 14.X are arranged between the calibration projection 16.X and the frontmost tip 12, which are shaped with respect to their respective projection maximum radius R E1max , ..., R E8max The calibration radius R K In this embodiment, eight preformed protrusions 14.X are provided. Since the maximum radius R of the protrusion E1max To R E8max , i.e. the thread outer 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 increased depth. Figure 3a The maximum radius R of the protrusion can be clearly seen in the diagram shown. E1max In this figure, the corresponding maximum radius R E1max To R E8max The increase curve of AEMax To express.
[0071] Figure 2a is a perspective view of the screw tip 12 of the screw 10, and Figure 1 Similar to the embodiment shown, the thread 20 starts at the screw tip 12 and extends along its helical line in the direction of the head.
[0072] 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. E2max The angle at the screw head forms a wrap angle U with the radius at the start when projected onto the normal plane relative to the screw center axis MA. With each rotation, the wrap angle U increases by 360°, wherein as the wrap angle U increases, the position of the outer radius of the thread at the corresponding angular position moves along the screw center axis in the direction of the head. The top view of the normal plane is Figure 2b Shown in.
[0073] In this example, the maximum value between two adjacent protrusions (for example, the angular position WPE2max With WP E3max The angular distance alpha between Max As an alternative, the angular distance alpha between the maximum values of two adjacent protrusions 14.X and 16.X is 120°. Max For example, it can also be 125°, so that the protrusions are not offset in the circumferential direction.
[0074] 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, for example, is at an angular position WP E3开始 Starting at and at angular position WP E3结束 Extends to the end of the third protrusion 14.3.
[0075] The angular distance alpha between two adjacent protrusions is preferably more than twice the angular distance beta between the protrusions.
[0076] Figure 3a The diagram schematically shows the course of the thread line GL at the outermost point of the thread tip within the scope of the helix along its development diagram within the wrap angle. It can be seen from the figure that 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 by a short dashed line. This short dashed line shows the course of the "basic thread", ie the course of the thread 20 without the partial projections 14.X, 16.X.
[0077] The solid line shows the course of the actual thread GL along the basic thread in the region of these projections, which protrude beyond the basic thread 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.
[0078] As can be seen from the figure, these protrusions are designed to be shorter in the circumferential direction and extend only within a short angular range not exceeding pi / 3 (60°). E2结束 With WP E3开始 The angular distance between the two lenses is approximately pi / 3 (60°).
[0079] The thread is formed in the tip region SB of the screw 10, ie at the outer thread radius R of the basic thread. AIn the increasing (in this example linearly increasing) area there are three calibration protrusions 16 .X.
[0080] The three calibration protrusions 16.X have the same protrusion maximum radius R E9Max , R E10max , R E11Max , which is equivalent to the calibration radius R K Calibration radius R of calibration protrusion 16.X K And the maximum radius of the bulge R E9Max , R E10Max , R E11Max Greater than the thread support radius R in the screw support area TB T .
[0081] 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 bearing region TB. AB With calibration radius R K The difference between them is large. This enables the calibration projection 16.X to be reliably manufactured with sufficient accuracy also using a rolling process. As a result, the tapping torque of such a screw can be more reliably reduced when screwing directly into light metal.
[0082] The circumferential extension of the projection is approximately equivalent to or preferably less than the angular distance of 60 ° of the encirclement. Thus, friction is only caused in a small helical angle, so that the screw-in torque can be kept small.
[0083] Figure 3b for Figure 3a The enlarged view of the detail of the illustration shown focuses on the calibration projection 16.X. In this enlarged view, it can be clearly seen that even for the projection closest to the bearing area TB, the difference in outer radius to the basic thread BL is still much greater than the difference in outer radius in the bearing area TB, where this difference is only R K -R T And according to the present invention, it is preferably less than 0.1 mm.
[0084] In this way, the calibration projection 16 .X can be precisely produced according to the technical principle of the invention by means of a rolling process in order to achieve a structure of the nut thread that is as precise as possible.
[0085] Between the calibration projection 16.3 closest to the support area and this support area, the wraparound angular position WP E12结束 The outer radius of the thread R A The thread outer radius R has a local minimum A (WP E12结束 ).
[0086] The thread outer radius R at this local minimum A (WPE12结束 ) and the radius of the support area R T The ratio is preferably less than 0.996.
[0087] Furthermore, at the end of the second calibration projection 16.2, that is, at the wrap-around angle position WP E11结束 At this point, another local minimum thread outer radius R is generated A (WP E11结束 ).
[0088] The thread is designed in such a way that the calibration radius R K Percentage exceeding the minimum mean value vs. calibration radius R K Beyond the support area radius R T The percentage ratio is greater than 1.4.
[0089] The minimum average value is the thread outer radius R at the first local minimum A (WP E12结束 ) and the thread outer radius R at the second local minimum A (WP E11结束 )’s average value.
[0090] Therefore, the design of the thread satisfies the following formula:
[0091] (R K / ((R A (WP E12结束 )+R A (WP E11结束 )) / 2))-1) / ((R K / R T )-1)>1.4 Figure 4 The extension of the protrusion in the axial direction is shown.
[0092] Figure 4 Schematic cross-sectional view AA of the thread 20 in the transition from the bearing area TB to the tip area SB. The thread 20 has, starting from its thread base GG, a thread flank (i.e., load flank 52) facing the head in the area of the calibration projection, which connects with a thread tip 54 having an elliptical profile. The thread tip 54 then connects again with the thread flank (i.e., guide flank 56) in the direction of the screw tip. The contour of the basic thread is indicated by a dotted line, which would exist in the section plane if there were no projections there. In this case, in the bearing area TB, the actual course corresponds to the course of the basic thread, wherein this basic thread has a load flank 42, a thread tip 44, and a guide flank 46.
[0093] The calibration projection 54 protrudes beyond the course of the basic thread to a limited extent in the circumferential direction. The calibration projection has a projection maximum radius R at its local maximum. AEmax, which in this example corresponds to the calibration radius R K .like Figure 4 As shown, in contrast to the course of the basic thread shown in dashed form, this projection also extends axially beyond the basic thread, wherein this projection is preferably rolled in during the rolling process.
[0094] from Figure 3b It can also be seen that at the angular position WP E12max In the area where the basic thread height still increases, 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 This makes it possible to manufacture the protrusion 54 more reliably.
[0095] This basic thread has an oval thread tip 44 in the bearing area. This thread tip is designed in Figure 5 Detailed description in.
[0096] The thread tip 54 has an oval cross-section, and its design and effect will be combined with Figure 6 Provide detailed explanation.
[0097] 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, precise profiling of the nut thread is particularly reliable.
[0098] The oval contour 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 the basic thread, which will be referred to below. Figure 6 This is explained in detail.
[0099] Figure 5 The cross section of the thread in the bearing area TB is shown, with a thread tip 44 having an oval cross section. This thread shape is also essentially present in the basic thread in the tip area SB of the screw, ie in the area between the projections.
[0100] The thread tip 44 has an ellipse SE in cross section. The thread tip 44 is connected to the guide side 46 in the direction of the screw tip and to the load side 42 in the direction of the screw head. The vertex SP of the thread tip is located at the vertex of the ellipse SE at the intersection with its major semi-axis HA.
[0101] The thread tip 44 merges with the load flank 42 at a transition point UP1 and with 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.
[0102] At the transition points UP1 and UP2 , tangent lines T1 , T2 , respectively, which define the flank angle, may be applied.
[0103] A tangent line T1 , which forms a load flank angle LF with the semi-major axis HA, abuts at the transition point UP1 .
[0104] The orthogonal 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 preferably designed in such a way 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 a sufficient curvature of the thread tip for a good material flow during displacement, thereby reducing wear of the thread tip during the trenching process.
[0105] Furthermore, the thread tip is preferably shaped in such a way that a line VL1 connecting the transition point UP1 and the vertex SP and the semi-major axis HA form a vertex angle VL1-HA which is in particular less than 45°, and is approximately 22° in the present embodiment.
[0106] The thread tip 44 is designed in such a way that the relations that apply to UP1 also apply to UP2 of the leading edge.
[0107] The tangent line T2 is located at the transition point UP2, which intersects the leading edge angle FF of the major semi-axis HA.
[0108] The orthogonal line to the tangent line T2 at the transition point UP2 intersects the major semi-axis at the intersection point BP2. The thread tip is preferably designed so that the distance between the tangent point BP2 and the transition point UP2 is less than 90% of the distance between the vertex SP and the intersection point BP2. In this way, the thread tip has enough curvature to allow the material to flow smoothly during the displacement process, thereby reducing the wear of the thread tip during the grooving process.
[0109] In addition, the shape of the thread tip is preferably such that the line VL2 connecting the transition point UP2 and the vertex SP forms a vertex angle VL2-HA with the semi-major axis HA. The vertex angle VL2-HA is particularly smaller than 45°, and is about 22° in the present embodiment.
[0110] Furthermore, a basic flank angle can be determined, which results from the sum of the load flank angle LF and the guide flank angle FF. In the present exemplary embodiment, this basic flank angle is 35°.
[0111] The thread is preferably designed in such a way that a line parallel to the tangent T1 through the apex intersects the thread base line at the perpendicular FP1. According to the 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.
[0112] In the described embodiment, the thread is designed in such a way that the distance A1 is approximately twice the distance A2 of the transition point from the semi-major axis HA. This allows an elongated thread shape to be achieved.
[0113] In this embodiment, the flank curves of the guide flank 46 and the load flank 42 are at least partially defined by elliptical profiles. The eccentricity of these flank ellipses FE1, FE2 is much smaller than the ellipse SE defining the thread tip.
[0114] Figure 6 A thread cross section of another thread shape in the tip region SB of a screw 10 is shown, wherein the thread tip 54 of the trenching region is shown in the region of the projection. The oval thread tip 54 contributes to improving the trenching properties and thus reduces the wear of the calibration projection designed in this way. In addition, the projection profile is opposite to the thread cross section of the basic thread with the thread tip 34, as would be present in this regard at the intersection of the thread and the projection if the basic thread were to run uniformly and continuously.
[0115] The apex SP is located at the corresponding projection R away from the center axis of the screw. E8max The maximum radius of the bulge at .
[0116] The direction of the ellipse along the tip is similar to Figure 5 The orientation of the tip ellipse is shown.
[0117] Since the thread has the same profile as the basic thread in the bearing area, the tangent T1 to the ellipse defining the thread tip at the transition point UP1 to the load flank in the convex area in the bearing area TB is parallel to the tangent T1 to the ellipse at the transition to the load flank in the bearing area TB. As a result, the two tangents form the same load flank angle with the semi-major axis HA. With reference to the guide flank, the above also applies to the tangent T2.
[0118] In this respect, the cross-sectional profile of the projection corresponds essentially to the profile of the bearing region. With respect to this projection, only the region in which the thread flanks follow the tangents T1, T2 is longer. This results in a pre-grooving of the thread line that is enlarged relative to the bearing region, with which the thread in the bearing region can engage by means of the flank region of the nut thread that is parallel to the pre-grooving.
[0119] The calibration projection closest to the bearing 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 bearing area. This ensures that the projection can be produced reliably and still produces a preformed nut thread that is only slightly larger.
Claims
1. A screw (10) for direct screwing into a component, in particular a component made of light metal material, comprising a head and a shank, wherein the shank is provided with a thread (20) having an outer thread radius (R A ) from a bearing area with a constant radius (R T ) decreases in the area of the tip region (SB) towards the screw tip (12), wherein the thread (20) decreases in the tip region (SB), i.e. at the thread outer radius (R A ) in a region which decreases towards the screw tip (12), has at least five circumferentially limited, radially extending projections (14.X, 16.X), wherein in the region of the projections (14.X, 16.X) the thread outer radius (R A ) is changed in a certain way so as to produce a maximum radius of the bulge corresponding to the bulge (R E1max , R E2max , R E8max ), where at least two of the protrusions - calibration protrusions (16.X) - have a maximum protrusion radius (R E10max ,、R E11max , R E12max ) is the same size and is equivalent to the calibration radius (R K ), the calibration radius is larger than the support area radius (R T ), wherein at least three preformed protrusions (14.X) are arranged between the calibration protrusion (16.X) and the frontmost screw tip (12), and the respective protrusion maximum radius (R E1max , R E2max , R E8max ) is smaller than the maximum protrusion radius (R E10max , R E11max , R E12max ), in addition, the maximum protrusion radius (R E1max , R E2max , R E8max ) decreases towards the screw tip (12).
2. The screw according to claim 1, characterized in that The radius of the support area (R T ) and a first protrusion toward the screw tip (12) between the thread outer radius (R A ) is smaller than the support area radius (R T ).
3. The screw according to claim 2, characterized in that: The thread outer radius (R A (WP E12结束 )) and the support area radius (R T ) is less than 0.
996.
4. The screw according to claim 2 or 3, characterized in that: The thread is designed in such a way that the calibration radius (R K ) exceeds the minimum mean value ((R A (WP E12结束 )+R A (WP E11结束 )) / 2) is a percentage of the calibration radius (R K ) exceeds the support area radius (R T ) is greater than 1.4, wherein the minimum average value is formed by the thread outer radius (R A (WP E12结束 )) and the thread outer radius (R A (WP E11结束 )).
5. The screw according to any one of the preceding claims, characterized in that Starting from the tip (12) in the region of the tip, the respective maximum radius (R AEmax ) and the thread outer radius (R A ) increases in line with the increase in .
6. The screw according to any one of claims 1 to 4, characterized in that The maximum radius of the protrusion (R AEmax ) increases in a decreasing manner starting from the screw tip (12).
7. The screw according to any one of the preceding claims, characterized in that In the convex (14.X, 16.X), at the first wrap angle position (WP) of the wrap angle (U) EX开始 ), the outer radius of the thread (R A ) is at the outer radius of the basic thread (R AB ) level, in the case of further increase, the thread outer radius (R A ) is equivalent to the maximum radius of the protrusion (R AEmax ), and in the case of further increase, the wrap angle position (WP) of the wrap angle (U) at the end of the protrusion EX结束 ), the outer radius of the thread is equivalent to the outer radius of the basic thread (R AB ).
8. The screw according to claim 7, characterized in that In the protrusion (14.X, 16.X), the outer radius of the thread (R A ) within the wrap angle distance (beta) from the basic thread outer radius (R AB ) starts to increase and then decreases again until it corresponds to the basic thread outer radius (R AB ), especially following a parabolic trend.
9. The screw according to claim 8, characterized in that For the thread (20) between two adjacent preformed protrusions (14.X), the basic thread outer radius (R AB ) increases linearly from the tip of the screw.
10. The screw according to any one of the preceding claims, characterized in that The support area radius (R T ) is greater than the calibration radius (R K )’s 90%.
11. The screw according to any one of the preceding claims, characterized in that The calibration radius (R K ) is at most greater than the support area radius (R T ) is 0.1mm larger.
12. The screw according to any one of the preceding claims, characterized in that The maximum radius of a preformed protrusion (R AEmax ) is greater than the next thread outer radius (R A ).
13. The screw according to any one of the preceding claims, characterized in that The wrap angle (U) between two adjacent projection maxima in the normal plane relative to the screw centerline corresponds to the wrap angle distance (alpha max ), where 360° / n-10° <alpha max <360° / n+10°, where n is between 2, 3 or 4, and the angular distance (beta) of the protrusion is less than 210° / n.
14. The screw according to any one of the preceding claims, characterized in that The projections (14.X, 16.X) also extend axially beyond the basic thread, in particular on both sides.
15. The screw according to any one of the preceding claims, characterized in that The length of the thread (20) in the tip region (SB) is less than five turns.
16. The screw according to any one of the preceding claims, characterized in that The slope of the thread line is about 5°-7°, which is equivalent to an increase of 3% to 5% in the outer radius of the basic thread per turn.
17. The screw according to any one of the preceding claims, characterized in that Thread root diameter (D K ) increases starting from the tip (12) in the tip region (SB).
18. The screw according to claim 17, characterized in that Starting from the screw tip (12) toward the head, the thread root diameter (D K ) is less than the basic thread radius (R AB ) increase.
19. The screw according to any one of the preceding claims, characterized in that The thread flank width is narrower in the axial direction and the thread has a guide flank (46, 56) towards the screw tip (12) and a load flank (42, 52) towards the screw head (18), wherein the guide flank and the load flank form a basic flank angle of 30° in particular.
20. The screw according to any one of the preceding claims, characterized in that The guide side (46, 56) and the load side (42, 52) are connected by a thread tip (44, 54), wherein the contour of the thread tip (44, 54) follows an elliptical path.
21. The screw according to claim 20, characterized in that The thread tip (44, 54) of the bearing area (TB) and / or the projection in the tip area (SB) are designed in such a way that at a contact point (UP1) in the transition section with the load side (42, 52), a load side angle (LF) of less than 30°, in particular less than 25° is formed with the tangent (T1) of the ellipse and the major semi-axis (HA) of the ellipse, and at a contact point (UP2) in the transition section with the guide side (46, 56), a load side angle (LF) of less than 30°, in particular less than 25° is formed with the tangent (T2) of the ellipse and the major semi-axis (HA) of the ellipse.
22. The screw according to any one of claims 20 or 21, characterized in that The distance between the contact point (UP1) and the semi-major axis (HA) is greater than 1 / 3*thread height*tan (load side angle), and the distance between the contact point (UP2) and the semi-major axis (HA) is greater than 1 / 3*thread height*tan (guide side angle).
23. The screw according to any one of claims 21 or 22, characterized in that A line (VL1; VL2) connecting the contact point (UP1; UP2) and the vertex (SP) of the semi-major axis (HA) at the thread tip forms a vertex angle (VL1-HA, VL2-HA) with the semi-major axis (HA) that is less than 55°, in particular less than 45°.
24. The screw according to any one of the preceding claims, characterized in that The thread tip is designed in such a way that a line orthogonal to the tangent line (T1, T2) at the contact point (UP1, UP2) intersects the semi-major axis at an intersection point (BP1; BP2), wherein 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).
25. The screw according to any one of claims 21 to 24, characterized in that A transition from the oval thread tip (34, 44) to the thread flank (32, 36; 42, 46) extends tangentially.
26. The screw according to claim 25, characterized in that The guide flank (46, 56) and / or the load flank (42, 52) extend along an elliptical path which curves in a direction opposite to an ellipse (SE) forming the thread tip (44, 54).
27. The screw according to claim 26, characterized in that The numerical eccentricity of the elliptical path of the guide flank (46, 56) and / or the load flank (42, 52) is less than the numerical eccentricity of the ellipse defining the thread tip.
28. The screw according to any one of claims 21 to 27, characterized in that The semi-major axis (HA) of the ellipse (SE) defining the thread tip is inclined in the direction of the guide flank (46, 56) at an angle not exceeding 10° relative to the normal plane to the screw center axis.
29. The screw according to any one of the preceding claims, characterized in that The spacing between adjacent thread flanks at 90% of the thread height is greater than 0.7 times the lead, where the flank width is less than 0.5 times the thread height.
Citation Information
Patent Citations
Self-tapping screw
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Radial extrusion thread-forming screw
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