HK1199480B - Screw element - Google Patents

Abstract

The present invention relates to a screw element, comprising a threaded shank and a screw tip, which is configured on one shank end, and a screw head, which is configured on the opposite shank end and has a force-application means, and having a screw thread which runs on the threaded shank and the screw tip. The screw tip, when viewed in the screw-in direction, has a front first tip portion, which tapers off towards the end of the screw element, and a second tip portion, which is adjacent to said first tip portion, having, when viewed in the cross section, a polygonal cross section, the enveloping circle diameter of which is larger than a core diameter of the first tip portion. The first tip portion has a circular cross section. On the transition between the first tip portion and the second tip portion, at least one end edge face which, in relation to a screw centre axis, is radially oriented in the sense of a diameter enlargement and which terminates in a vertex of the polygonal cross section, which lies on the enveloping circle of the second tip portion is configured. The screw thread is configured without interruption over the first and second tip portions of the screw tip.

Description

Screw member

Technical Field

The present invention relates to a screw member according to the preamble of claim 1.

Background

A screw member of this type is described in european patent application EP0869287B 1. In particular, such screw elements are used in particular for screwing the screw element into different materials, such as wood and plastic, without predrilling the screw hole in the bottom hole beforehand. The screw member is first screwed directly into the corresponding material by drilling the thread tip (gewinnespitze) into the material, with a pressing effect. The thread running in the screwing direction up to the front end has the effect of a tapered end (greifsptz), so that the screw part can be inserted and drilled smoothly with little axial pressure, i.e. mainly by rotation. In the known screw element, the region of the core with a polygonal cross section extends as far as the front flank of the thread tip. In addition, polygonal core sections have convexly crowned sides and corners (which may likewise be rounded). The polygonal corner lies on an envelope circle, the diameter of which can be smaller than/equal to, in particular equal to, the diameter of the cylindrical core of the threaded rod. According to this document, the thread point, which is pressed into the material by the radial pressing action due to the torque generated by the expansion and collapse of the polygonal core cross section during rotation, produces a radial pressing action, so that the known connection, on account of its self-tapping action, is able to achieve the further avoidance of chip formation (Spanbildung) during screwing in.

However, when using the known screw element, in particular when screwing it into hardwood, splitting can occur as a result of the pressing effect of the screw tip which is polygonal in cross section. In addition, such a screw member requires a relatively large axial force at the beginning of screwing in to enable the screw thread of the screw tip to be screwed in.

Disclosure of Invention

The basic object of the invention is to further improve such a screw element with respect to its properties, in particular to further avoid the phenomenon of splitting and to further reduce the axial force required for screwing in.

According to the invention, this object is achieved by the features of the characterizing portion of claim 1. By combining the following: the end tip portion tapers, viewed in the screwing-in direction, with an end face edge adjacent to the end tip portion and oriented radially and serving as a cutting or milling edge, and the polygonal tip portion is adjacent to the end tip portion, and the screw thread extends continuously from the first end tip portion of the screw tip to the second end tip portion adjacent thereto, on the one hand, so that the screw can be screwed in easily, and on the other hand, so that the continuously extending thread can be inserted as soon as the conical region of the end tip is screwed in, and the cutting effect of the radially oriented end face edge of the polygonal portion is increased by the uninterrupted axial force action of the thread, so that the screw part according to the invention can be screwed in into the corresponding material with greater ease. The maximum diameter of the conically tapering section of the front end is designed to be smaller than the diameter of the enveloping circle of the polygonal section adjoining it, so that it can be screwed easily into the corresponding material. The cleaving effect will also be significantly reduced in this way. According to the invention, it is advantageous to design the tapering tip section as a pointed cone with a cone apex angle of 10 ° to 40 °, in particular 20 °. In this case, it is expedient for the length of the conical tip section of the front end to lie in the range from 0.8 to 2 times the pitch of the screw thread of the screw member according to the invention. The design of the thread tip as a tapered portion according to the invention facilitates easy screwing of the screw member according to the invention into the corresponding material, since the angle of the taper is small and the diameter becomes small compared to the diameter of the screw shank. The polygonal tip portion adjoining the conical portion preferably has an enveloping circle diameter which is greater than/equal to the maximum core diameter of a threaded rod with a circular cross section. This results in that, due to the presence of the core edge (Kernkante) formed on the polygonal tip portion, which preferably extends parallel to the central longitudinal axis, the threaded bore formed by the end face edge, which acts as a cutting edge, at the front end, as viewed in the screwing-in direction, is not narrowed again by the spring-back of the respective material into which the screw element according to the invention is screwed. Because the possibly resilient material will be squeezed radially or apart by the formed core ridges, the screw shank adjoining the polygonal tip portion can thus be inserted into the bore hole created by the screw tip without encountering great resistance.

Drawings

Further advantageous embodiments of the invention are contained in the dependent claims, which will be explained in detail with the aid of the exemplary embodiments shown in the figures. In the drawings:

FIG. 1 shows a perspective view of a screw member according to the present invention;

FIG. 2 shows a perspective view of the screw member according to FIG. 1 without the screw threads;

FIG. 3 shows a longitudinal section of the screw member according to FIG. 2 without the screw head;

FIGS. 3A-3C illustrate cross-sectional views taken along section lines A-A, B-B, C-C in FIG. 3;

FIGS. 4, 5 and 6 show cross-sectional views of alternative embodiments of a polygonal tip portion of a screw member according to the present invention;

FIG. 7 shows a side view of the screw member according to the invention as in FIG. 1;

FIGS. 7A-7C illustrate cross-sectional views of the screw member of FIG. 7 taken along section lines A-A, B-B and C-C in accordance with the present invention;

FIG. 8 shows a side view of the screw member of FIG. 7 in a position rotated 45 compared to the position of FIG. 7;

FIGS. 8A-8C show cross-sectional views taken along lines A-A, B-B and C-C in FIG. 8;

FIG. 9 shows a perspective view of another embodiment of the screw member according to the present invention;

fig. 10 shows a perspective view of the screw member according to the invention as shown in fig. 9 without the screw thread.

List of reference numerals

1-screw member

2-threaded rod

4-screw tip

4 a-tip part

4 b-tip part

5-screw head

7-stress handle

9-end edge surface (end edge)

12-screw thread

13-thread path

14-enveloping circle

15-corner point

18-core edge (cutting edge)

22-core edge

b-distance

D-direction of rotation

d_gDiameter of the thread

d_hDiameter of enveloping circle

d_h1Diameter of enveloping circle

d_h2Diameter of enveloping circle

d_kCore diameter of tip portion 4a

d_sMaximum core diameter of the threaded rod 2

_g1-orthogonal straight line

_g2-orthogonal straight line

X-X-central longitudinal axis

Z-direction of rotation

Like parts are provided with like reference numerals in the different figures of the drawing.

Detailed Description

With respect to the following description it is emphasized that the invention is not limited to these embodiments and therefore not limited to all or a plurality of the described combinations of features, but rather each individual sub-feature of any/each embodiment is significant both individually (apart from all other sub-features described in connection therewith) and in combination with any feature of another embodiment.

As shown in the figures, the screw element 1 according to the invention comprises a threaded shank 2, a screw tip 4 formed at one end of the threaded shank 2, and a screw head 5 formed at the other end opposite the screw tip 4, wherein the screw head 5 has a force-receiving shank 7 for a rotary tool (Drehwerkzeug). The screw head 5 can be configured, for example, as a countersunk head, round head or flat head, and the screw head 5 can also be formed as a cylindrical extension of the threaded shank 2. The force-receiving shank 7 can be configured as an elongated slot, a cross-shaped slot or as an internal force-receiving shank, for example in the shape of an internal hexagon or an internal star, or the force-receiving shank 7 can also be configured as an external hexagon on the screwhead 5, for example.

A screw thread 12 extends on the threaded shaft 2 and on the screw tip 4. The thread is preferably formed by a thread path (gewinnowing) 13 extending in the form of a helix, the cross-section of said thread path 13 being designed, for example, as a triangle (see fig. 7, 8). It also falls within the scope of the invention for the thread 12 according to the invention to be configured as a multiple-start thread, for example consisting of two helically arranged threads arranged offset in the circumferential direction.

The screw thread 12 according to the invention is preferably configured as a self-cutting or self-forming thread. The thread 12 according to the invention can have a constant pitch or a varying pitch over the entire thread area. In the embodiment shown, the maximum thread diameter d of the thread 12 according to the invention_g(i.e. the nominal diameter of the screw member according to the invention) is kept constant in the region of the threaded shank, so that in this region there is no variation in the thread diameter. The pitch of the screw thread according to the invention is preferably the nominal diameter d of the screw thread according to the invention (precisely when the screw thread according to the invention is a single thread)_g40% to 70%.

According to the invention, the screw tip 4 comprises two tip portions 4a and 4b, that is to say, a first tip portion 4a at the front end and tapering towards the end of the screw member, as seen in the screwing-in direction Z, and a second tip portion 4b adjoining it. In a cross-sectional view of the central axis X-X perpendicular to the longitudinal directionThe core of the tip portion 4b has, seen in this figure, a polygonal cross-section, the core of the tip portion 4b having an envelope circle 14 extending through the polygonal apex thereof, the envelope circle having a diameter d_h(see fig. 3B.) as shown in fig. 1, the first tip section 4a is preferably designed as a pointed cone and its cone apex angle α can be in the range from 10 ° to 40 °, in particular 20 ° (see fig. 3.) the first tip section 4a, which is conical in shape, has a circular core cross section extending perpendicularly to the central longitudinal axis X-X. the screw thread 12 extends over the entire screw tip 4 and its radial thread height decreases gradually towards the end of the conical tip section 4a to 0. in the range of the second tip section 4B, which is polygonal in cross section, the thread 12 preferably extends with a constant thread height, so that in the region of the tip section 4B the thread 12 has the same nominal thread diameter d as in the region of the threaded shaft 2_g. The diameter of the envelope circle 14 of the polygonal tip section 4b is greater than the core diameter d of the screw core in the region of the tip section 4a_k(see FIG. 3). According to the invention, at the transition between the first pointed end section 4a and the second pointed end section 4b, at least one end edge 9 oriented radially with respect to the longitudinal central axis X-X is present on the second pointed end section 4b, to be precise, in the direction of increasing diameter, the end edge 9 ends at a corner point 15 of the polygonal cross section located on the envelope circle of the second pointed end section 4 b. The radially extending end edge surface 9 is formed in the form of a cutting edge or a milling edge. In the shown embodiment, the polygonal cross-section of the second tip portion 4b has 4 corner points 15, thus forming 4 end facets 9 (see fig. 2), more precisely at the periphery of the screw member 1 according to the present invention. As can be seen in particular from fig. 1, the screw thread 12 extends continuously without interruption over the first and second pointed end sections 4a, 4b, so that the screw thread 12 is also formed in the region of the end face edge 9. In fig. 2, which shows only the screw core of the screw element 1 according to the invention, specifically the screw core in the region of the threaded shaft 2 and in the region of the screw tip 4, it can be clearly seen that the end surface ridge 9 is formed in the transition region from the first tip portion 4a to the second tip portion 4 b. The end face edge 9 here extends radially towards the longitudinal axis X-XAnd (6) stretching. Diameter d of the envelope circle of the second tip portion 4b_hGreater than or equal to the maximum core diameter d of the threaded rod 2 with a circular cross-section_sThis is advantageous. Here, it is advantageous when the diameter of the envelope circle of the second tip end portion 4b, which is polygonal in cross section, is constant over its axial length. As can be seen from the figures, the diameter of the base surface of the first thread section 4a in the form of a cone in the transition region between the first and second tip portions 4a, 4b, is greater than the maximum core diameter d of the threaded shank 2_sIs small. Furthermore, according to the invention, the outer diameter d of the screw thread 12 in the region of the second pointed end section 4b and also in the region of the threaded shank 2 is designed such that_gLarger than the maximum enveloping circle diameter d of the polygonal tip portion 4b_h。

In the embodiment shown, the thread 12 extends over the entire length of the threaded rod 2. However, it is also within the scope of the invention for the thread 12 not to extend over the entire length of the threaded rod 2, but for example to form a shank without a thread between the threaded portion of the threaded rod 2 and the screw head 5, so that only a partial thread is present on the threaded rod 2.

Furthermore, it is advantageous according to the invention if the length of the first tip portion 4a lies in the range from at least 0.8 times to at most 2.0 times the pitch S of the thread 12.

As can be seen in particular from fig. 3A to 3C and 4 to 6, the second pointed end section 4b is formed in a polygonal cross section in such a way that it is formed as a quadrilateral with 4 corner points 15. Furthermore, it is expedient to design the lines of intersection g of the polygonal cross-section such that the 4 corner points 15 each lie on a respective one of the lines of intersection g₁、g₂Upper, straight line g₁、g₂Extending orthogonally to the central longitudinal axis X-X and the respective distances b of the 4 corner points 15 from the longitudinal axis X-X are equal. Furthermore, it is expedient for the core edge 22 connecting the corner points 15 to be configured concave, as seen in cross section, as can be seen in particular in fig. 6. The core edge 22 may also extend linearly. In the embodiments shown, the tips are all shownThe polygonal cross-section of the end portion 4b is quadrangular, but equally triangular cross-sections, or more than four corners may be chosen according to the invention. Preferably, it is designed with a regular cross section. The corner points 15 of the respective cross-section, which are arranged one after the other in the longitudinal direction of the polygonal-sectioned tip portion 4b, all lie on a straight line extending parallel to the central longitudinal axis X-X, so that a straight core edge 18 is formed, so that an additional milling effect can be obtained when the material into which the screw member 1 according to the invention is screwed is reshaped. As shown in FIG. 6, the polygonal (i.e., quadrangular) cross section of the tip portion 4b is configured to surround the orthogonal straight line g₁、g₂Flip symmetry (klappsymmetrisch). Fig. 4 shows a different shape, in which the entire core edge 22 and thus the core edge surface is configured as a straight line g relative to the normal₁、g₂Fig. 4 shows a design in which the side or surface sections, which originate from each corner point 15 or core edge 18 and are drawn in the direction of rotation, are inclined radially (rails) in the direction of the longitudinal axis X-X in such a way that they enclose an acute angle β of less than 20 ° with the respective line running through the corner point 15 and then run approximately linearly to the next corner point 15 in the direction of rotation, fig. 4 shows a suitable such shape according to the invention when the direction of rotation D is clockwise, fig. 5 shows a corresponding shape according to the invention when the direction of rotation D is counterclockwise, fig. 3 to 3C show the polygonal cross-sectional shape of the polygonal tip section 4b corresponding to fig. 4, fig. 7 and 8 also select the corresponding cross-sectional shape of the polygonal tip section 4b, the polygonal cross-sectional shapes shown in fig. 4 and 5 are designed in such a way that the cutting or milling effect of the cutting edge 18 can be achieved better, which, for the embodiment shown in fig. 4, also results in a greater resistance to a loosening of the screw according to the invention when the embodiment shown in fig. 5 is released.

FIGS. 9 and 10 show a method according to the inventionThe design of the screw element 1, which corresponds essentially to the screw element 1 shown in fig. 1 to 8, differs, however, in that: the envelope circle diameter d of the envelope circle 14 of the polygonal tip portion 4b over the entire length of the polygonal tip portion 4b_hNot constant and equal but the diameter d of the enveloping circle_hWith the diameter d of the enveloping circle in the region of the end edge face 9_h1Starting from this point, it becomes larger in the direction of the threaded shank 2, more precisely, preferably continuously until the maximum envelope circle diameter d is reached in the remaining region of the polygonal tip portion 4b_h2. Here, the diameter d of the enveloping circle_hThe length covered by the process of increasing to the maximum diameter is preferably 10 to 50% of the total length of the polygonal tip portion 4 b. Diameter d of the enveloping circle in the region of the end face edge 9_h1Within the range of the polygonal tip portion 4b (within this range, there is a constant enveloping circle diameter d_h2) Maximum diameter d of enveloping circle_h2The difference between the diameters is the maximum enveloping circle diameter d_h5% to 20%.

As is shown in the figures, in the screw member 1 according to the invention, the outer thread edge of the thread 12 extends over the threaded shank 2 and over the entire polygonal tip portion 4b with a constant radius and a constant thread height at all times. Throughout the conical tip section 4a, up to the end of the tip section 4a, the thread path 13 extends helically, the diameter of which decreases continuously with the thread height up to 0.

In an advantageous embodiment, which is not shown in the drawings, the thread edge of the thread 12 can furthermore be formed in a wave-like manner, at least in the region of the thread segments 4 and at the same time in the region of the thread flanks, so that a series of peaks and valleys is present. Reference is hereby made in full to German patent application DE3335092A 1.

The invention is not limited to the embodiments described and illustrated above, but also encompasses all structures that perform the same function in the inventive sense. It should be emphasized that embodiments of the present invention are not limited to all features that are combined together, but rather that each individual sub-feature remains inventive when separated from all other sub-features. The invention is not limited to the combination of features defined in claim 1, but can also be defined as any other combination of certain features from all the individual features disclosed. This means that in principle and in practice each individual feature described in claim 1 can be deleted or replaced by an individual feature disclosed elsewhere in this application.

Claims (19)

1. Screw element (1) comprising a threaded shaft (2), a screw tip (4) which is formed at one shaft end, a screw head (5) which is formed at the opposite shaft end and has a force-receiving means (7), and having a screw thread (12) which extends over the threaded shaft (2) and the screw tip (4), wherein the screw tip (4) has a first tip portion (4a) which is located at the front end, viewed in the screwing-in direction (Z), and tapers towards the screw element end, and a second tip portion (4b) which adjoins the first tip portion and has a polygonal cross section, viewed in cross section, and the diameter (d) of the envelope circle of which is the diameter (d)_h) Is greater thanA core diameter (d) of the first tip portion (4a)_k) Characterized in that the first tip section (4a) has a circular cross section and in the transition between the first tip section (4a) and the second tip section (4b) at least one end flank (9) is present on the second tip section (4b) which is oriented radially in the direction of increasing diameter with respect to the central longitudinal axis (X-X), the end flank (9) terminating in a corner point (15) of the polygonal cross section which is located on the envelope circle (14) of the second tip section (4b), and in that the screw thread (12) is formed on the first tip section (4a) and the second tip section (4b) of the screw tip (4) in a continuous manner without interruption.

2. The screw member according to claim 1, wherein the enveloping circle diameter (d) of the enveloping circle (14) of the second tip portion (4b)_h) Greater than/equal to the maximum core diameter (d) of the threaded rod (2)_s)。

3. The screw member according to claim 2, wherein the threaded shaft (2) is circular in cross-section.

4. The screw member according to one of the claims 1 to 3, wherein the second tip portion (4b) of the screw tip (4) has an enveloping circular diameter (d)_h) Is constant over its axial length.

5. The screw member according to one of the claims 1 to 3, characterized in that the second tip portion (4b) of the screw tip (4) has an envelope circle diameter (d) in a transition region from the first tip portion (4a) to the second tip portion (4b)_h1) Smaller than the diameter (d) of the enveloping circle of the end of the second tip portion (4b) facing the threaded rod (2)_h2)。

6. The screw member according to one of claims 1 to 3, wherein the first tip portion (4a) is configured as a pointed cone with a cone apex angle (α) in the range of 10 ° to 40 °.

7. The screw member according to claim 6, wherein the apex angle (α) of the first tip portion (4a) is 20 °.

8. The screw member according to claim 6, wherein the core diameter (d) of the bottom surface of the first tip portion (4a) configured as a pointed cone at its transition between the first and second tip portions (4a, 4b)_k) Is smaller than the maximum core diameter (d) of the threaded rod (2)_s)。

9. The screw member according to one of claims 1 to 3, wherein, in the region of the second tip portion (4b) and on the threaded shaft (2), the screw thread (12) has a thread outer diameter (d)_g) Is larger than the maximum enveloping circle diameter of the second tip portion (4 b).

10. The screw member according to one of claims 1 to 3, wherein the length of the first tip portion (4a) is 0.8 to 2 times the maximum pitch of the screw thread (12).

11. The screw member according to claim 10, wherein the pitch (S) is 40% to 70% of the maximum thread outer diameter when the thread is a single-start thread.

12. The screw member according to one of claims 1 to 3, wherein the threaded outer diameter (d) on the first tip portion (4a)_g) Starting from 0 at the end of the screw member, to the maximum thread outer diameter of said second tip portion (4 b).

13. The screw member according to one of claims 1 to 3, wherein the polygonal cross-section of the second tip portion (4b) has at least three corner points (15), which corner points (15) lie on an envelope circle (14) of the second tip portion (4 b).

14. The screw member according to claim 13, wherein the polygonal cross-section of the second tip portion (4b) has four corner points (15), which corner points (15) lie on an envelope circle (14) of the second tip portion (4 b).

15. The screw member according to claim 14, wherein two lines (g) intersecting each other and orthogonal to the central longitudinal axis (X-X) with the four corner points (15) lying on a polygonal cross-section₁、g₂) And four corner points (15) each having an equal distance (b) to said central longitudinal axis (X-X).

16. The screw member according to claim 14 or 15, wherein the four corner points (15) of the polygonal cross-section of the second tip portion (4b) are arranged in a longitudinal direction in a sequential arrangement on a line extending parallel to the central longitudinal axis (X-X) so as to form a rectilinear core edge (18).

17. Screw member according to claim 15, wherein the corner points (15) of the polygonal cross-section are connected by a core edge (22) of concave configuration, thereby forming a polygonal cross-section, which is always oriented with respect to orthogonal straight lines (g) extending through the corner points (15)₁、g₂) The turnover is symmetrical.

18. The screw member according to claim 15, wherein a core edge (22) connecting corner points (15) of the polygonal cross-section is configured with respect to orthogonal straight lines (g) extending through the corner points (15)₁、g₂) Is not limited toSymmetry, so that the screw element (1) is raised in the screwing-in direction or screwing-out direction with respect to the cutting or milling effect.

19. The screw member according to one of claims 1 to 3, wherein the thread (12) has an outer thread edge which, viewed in the axial direction of the central longitudinal axis (X-X), extends in a helical manner and over the threaded shank (2) with a constant radius and over the entire screw tip (4) extends in a helical manner with a continuously decreasing radius.