阅读说明：本技术 设有用于螺丝钉沉孔的铣肋的螺丝钉及此螺丝钉的用途 (Screw with milling ribs for screw counter bore and use of such screw ) 是由 克劳斯·豪恩斯特拉普·迪星 于 2019-12-16 设计创作，主要内容包括：为了避免木材因沉孔螺丝钉(1)而在孔的边缘出现穗缘,螺丝钉头(2)设有渐缩下侧和倾斜铣肋,而在渐缩下侧上的铣肋之间则有凹穴。(In order to avoid the occurrence of spiking of the wood at the edge of the hole due to the countersunk screw (1), the screw head (2) is provided with a tapered underside and inclined milling ribs, whereas there are pockets between the milling ribs on the tapered underside.)

1. A screw (1) comprising a screw head (2) at a first end (1a) of the screw (1) and a shank (3) extending from the screw head (2) towards an opposite second end (1b) of the screw (1), a thread (5) being provided on the shank (3) to screw the screw (1) into a material by means of a fixing tool;

wherein the screw (1) has a longitudinal central axis (6) extending between the first end (1a) and the second end (1 b);

wherein the screw head (2) has an upper side (2a) and a lower side (2b), wherein the upper side (2a) comprises a tool receiver (4) for engaging the fixation tool;

wherein the lower side (2b) of the screw head (2) comprises a tapered surface (7) having a tapering direction (19) towards the shank (3), the tapering direction (19) being in a plane containing the central axis (6); the tapered surface (7) is provided with a plurality of milling ribs (8), each milling rib (8) comprising a front side (15) directed towards a milling direction and defined by a milling edge (17) for milling material during counter-boring of the screw head (2), and each milling rib (8) comprising a rear side relative to the front side;

wherein the front side (15) is inclined with respect to the tapering direction (19), wherein the inclination of the front side (15) and the milling edge (17) are directed for pressing the milled material inwards towards the shank (3) during countersinking of the screw head (2) in the material;

wherein smoothly curved pockets (14) are provided between the milling ribs (8), which pockets (14) extend into the underside (2b) of the screw head (2),

characterized in that each pocket (14) curves smoothly concavely from one milling rib (8) to the adjacent milling rib (8).

2. Screw according to claim 1, characterised in that the front side (15) of the milling rib (8) is a flat plane.

3. Screw according to claim 1 or 2, characterized in that each pocket (14) is smoothly concavely curved from the front side (15) of one milling rib (8) to the adjacent milling rib (8).

4. Screw according to any one of the preceding claims, wherein the lower side (2b) of the screw head comprises a flat edge region (11) along a peripheral edge (12) of the screw head (2) and is defined by a cutting edge (13) at the peripheral edge (12) to cut into the material during the time the screw head (2) is countersunk into the material; the flat edge region (11) extends from the cutting edge (13) to the pocket (14) and the milling rib (8).

5. Screw according to claim 4, characterised in that the flat edge region (11) has a surface parallel to a plane perpendicular to the central axis (6).

6. Screw according to claim 4 or 5, characterised in that the width of the flat edge zone, measured from the periphery of the head to the end of the rib close to the periphery, is between 1% and 25% of the diameter of the screw head (2).

7. Screw according to claim 4 or 5 or 6, characterized in that the pocket (14) forms a smoothly concavely curved connecting line (C3) with the flat edge region (11) at its connection to the flat edge region (11).

8. A screw according to any one of the preceding claims, in which the milling edge (17) will follow a frustoconical surface to mill a frustoconical hole in the material when the screw (1) is countersunk.

9. Screw according to any preceding claim, in which the milling rib (8) has a constant width from the shank (3) towards the peripheral edge (12) of the screw head (2).

10. Use of a screw according to any of the preceding claims for threading into wood or fibre composite material or into polymers.

Technical Field

The invention relates to a screw, in particular a wood screw, according to the preamble of the claims, wherein the underside of the screw head comprises a tapered surface with a plurality of inclined milling ribs to press the milling material inwards towards the shank during the counter-boring of the screw.

Background

In order to properly and smoothly countersink the screw head into the material, it is common practice to provide the underside of the screw head with a toothing, for example a milled rib. The ribs are often oriented so that they lie in a plane that also contains the central axis of the screw. In other cases they are inclined to such a plane. In a further aspect, the insection is curved, for example along a helical path or in an S-shaped curve. Examples of such various shapes are disclosed in german patent application DE3344048a1, german utility model patent DE9106746U1, european patent application EP0705987, EP1182367, EP2522865, french patent application FR2784722, british patent application GB2227540, GB972653, GB2336415, US patent US586232, US1151861, US5199839, US7293947, USD708509, chinese patent application CN 101498334A.

In all of the above prior art, the fact that the inclined milling ribs are pressed outwards means that the material milled by the milling ribs is pressed in an outward direction as seen from the screw shank.

For better understanding, the term "outward-pressing milling-rib" is used herein to skew the milling rib, and the material is pressed outward by the screw during its countersinking into the material. Similarly, the term "inward-pressing milling-rib" is used to skew the milling rib, and the material is pressed inward toward the shank by the screw during the time it is countersunk into the material. The inwardly pressed ribs have a front side which is inclined at an angle to the screwing-in direction, so that the part of the ribs which is close to the periphery of the screw head is guided during screwing-in of the screw. The outwardly pressed ribs have a front side which is inclined with respect to the screwing-in direction, so that the part of the ribs which is close to the shank is leading during screwing-in of the screw.

The term "front-side" of the milling rib is used herein to refer to the side of the milling rib that is pushed against the material as the screw is counter bored into the material during rotation. The term "posterior side" refers to the side of the milled rib opposite the anterior side.

European patent application EP3067575a1 discloses inwardly pressed milling ribs protruding from a conical surface and aligned in an inclined orientation which forces the wood toward the shank during counter-boring.

The ribs disclosed in european patent application EP3002468a1 protrude from an inclined surface on the underside of the head. The ribs are helically curved and offset and also press the wood inward toward the shank during counter-boring. The bending of the ribs is such that when the ribs begin to engage the wood surface during countersinking, the edge near the shank is parallel to the direction of rotation, so that the initial effect on the countersink is cutting rather than milling for the first period. Only during further countersinking when the rest of the rib engages the wood, the angle gradually deviates from the tangential direction and the initial cutting of the wood surface is followed by a milling action. During the continuation of the countersink, the deeper wood is first cut and then milled by the curved ribs.

The screw disclosed in GB15102 has a straight, inwardly-directed bead which is integral with the underside of the head. The milling edge is formed in part by a recess in the surface of the conical underside and is angled so that the wood being milled is pressed inwards towards the shank. The countersunk hole formed by the screw is conical. This reveals that for milling edges the emphasis is placed on "they never appear on the surface of the head" (in no case do the y come out at the face of the head). This is integrated into a pocket in the head to maintain strength and have the appearance of a typical screw. Curved milling ribs are disclosed in taiwan patent publication TW201422932A and chinese patent application CN103047245A, respectively. Milling ribs are provided in the conical underside of the head to form conical counterbores.

For a proper counter bore, the shape of the screw head and milling ribs can have a substantial effect, even with small variations. For example, the effects of screw head shape and milled rib shape can cause the counter bore to appear clean, or can cause broken wood fibers to become a fringe around the hole, which is undesirable.

Disclosure of Invention

The invention aims to provide technical improvement. In particular, it is an object to provide a screw having improved counterboring capabilities in a material, such as wood. This is achieved by the screws described in more detail below.

Alternatively to wood, screws may be used for counterbores in other materials, including certain composite materials (e.g., wood fiber based composites) and polymers (e.g., fiber reinforced polymers).

The screw includes a screw head at a first end of the screw and a shank extending from the screw head toward an opposite second end of the screw. Threads are provided on the shank for screwing the screw into the material by means of a fastening tool. The screw has a longitudinal central axis extending between a first end and a second end. The screw head has an upper side and a lower side, wherein the upper side comprises a tool receiver for engaging a fastening tool.

The underside of the screw head has a tapered surface with a direction of taper towards the shank. The direction of taper is defined in a plane that includes the central axis, thus being parallel to the central axis and extending through the center of the screw. The tapered surface is provided with a plurality of milling ribs. Each milling rib comprises a front side which is directed towards the milling direction and is defined by a milling edge for milling material during countersinking of the screw head.

The front side is inclined with respect to the tapering direction. The inclination and the milling edge of the front side are directed such that the milling rib presses the milled material inwards towards the shank during the countersinking of the screw head in the material. The term inward pressure is explained in more detail in the above description.

In some embodiments, the milling rib has a planar front side, and the milling edge is accordingly in the plane of the planar front side of the milling rib. Both of these aspects have in fact resulted in improved, efficient and aggressive cutting of the wood fibers during the counter-boring. The result of a planar front side has been more efficient than a rounded front side, the latter being for example scalloped as disclosed in US5199839 or the spiraled edge of EP3067575a1 by Kwantex.

Pockets are provided between the milling ribs. The pockets extend from a first location near the shank toward a second location near the periphery of the head. The pockets are concave and curve smoothly concave from one milling edge to the adjacent milling edge. This smoothly curved concave recess begins at a second position at or near the periphery of the screw head and continues to a first position at or near the shank. For example, the recess extends to the shank, where it follows the cross section of the shank. The concave smooth curvature is measured relative to the frustoconical surface underlying the head of the screw such that the concave recess curves smoothly into the underside of the head.

This is in contrast to the aforementioned CN103047245A, in which the bottom of the pocket is shaped to form a smoothly convex, i.e., a ground flat conical surface.

The combination of the direction of the obliquely inward pressure and the recessed pocket has shown surprising results when used in practice, as explained in more detail below. When countersunk a screw head into a material, such as wood, a front side with a cutting edge, especially if the front side is planar, is extremely efficient. The screw achieves an efficient stop in the counter bore despite aggressive milling, since the front side of the plane is directed such that the milled material is pressed inwards towards the shank. The milled material accumulates in the counterbore due to the inward pressure of the material and compresses therein. During this compression, a layer of compact material gradually forms on the tapered underside of the screw head and accumulates in the recessed pockets between the ribs during counterboring until the volume between the ribs fills with compact material so as to avoid further milling of the ribs. More material is compressed in the lower concave pocket than in the upper convex pocket of the prior art, which results in a more compact and solid connection between the screw head and the material without breaking the material, particularly wood. Thus, the extra material occupied in the recessed pocket acts as a damping during screw stopping and as an adhesive between the screw head and the material that has been driven into by the screw head counter bore.

In particular for wood, as soon as the screw head is countersunk into the material, the result during the countersinking is immediately that the screw has stopped properly without breaking the wood.

Incidentally, when a piece of material (for example a wood component, such as wood) is screwed against a secondary structure (for example a second wood component, such as a beam), the screw has a high tightening force of the bottom against such a secondary structure underneath due to the compact material in the recessed pocket. For this reason, the front side of the plane and the oblique orientation thereof milled inwards have surprisingly different positive effects.

In some embodiments, the milling ribs have a constant width. For example, the front and back sides of the plane of the milled ribs are parallel.

The recess need not extend all the way to the periphery of the head. Alternatively, a flat narrow edge region is provided on the cephalad underside of the periphery to cut the wood fringe. For example, the flat edge region connects the periphery and the tapered surface. At the periphery of the flat edge region, a cutting edge is provided to help cut the wood fibers at the edge of the countersink.

In some embodiments, the flat edge region has a surface in a plane perpendicular to the central axis. In some cases, the width of the flat edge region (measured radially from the periphery of the screw head to the rib near the periphery of the screw head) is in the range of 1-25% of the diameter of the screw head, for example 1-5% of the diameter.

Alternatively, instead of or in addition to the flat edge region, a collar is provided along the circumference of the screw head, which extends towards the second end for a distance, typically in the range of 0.1 to 5 mm, depending on the size of the screw. Such a collar makes it more efficient to cut wood fibers at the counterbore edge. In yet another alternative, the sharp edge is disposed at the periphery, and the edge is directed toward the second end.

When counterboring a screw, it has been experienced that the edge of the wood around the counterbored screw is minimized and much less than when using similar screws of the prior art.

Alternatively, the screw includes a cut in the longitudinal direction of the screw along the front of the thread to cut or mill a path into the material. The front portion is at the second end of the screw.

Alternatively, to reduce the resistance on the screw, the screw includes a knurled shoulder between the thread and the head. Typically, the knurls are provided in direct extension of the thread. For example, the knurled shoulder is arranged at a distance from the head, which may optionally correspond to 1 to 40% of the total length of the screw.

Although such screws may be used with a wide variety of materials, screws are particularly useful for threading into wood.

The typical overall length L of the screw is in the range of 10-1000 mm, although it may be longer.

The thread typically corresponds to a length of at least 10% of L.

If knurls are provided, these knurls are typically in the range of 1-40% L.

Typical angular values of the tapered underside of the head to the longitudinal axis are in the angular range of 20 deg. to 60 deg.. Thus, the total span of the counterbore frustoconical bore is 40 ° to 120 °.

Typically, the milled rim is shaped such that the final counter bore is conical. However, it is also possible for the bead to be shaped to form a more rounded counterbore, for example a counterbore with an upper convex counterbore surface, including an ellipsoidal, hemispherical, or even a concave surface.

Drawings

The invention will be described in more detail with reference to the accompanying drawings, in which:

FIG. 1 is an overall view of a screw;

figure 2a is a side view of the screw head,

figure 2b is a view of the underside of the screw head in a direction parallel to the axis of the screw,

figure 2c is a different side view of the device,

FIGS. 2 d-2 f are different perspective views of the underside of the head of the screw;

figures 3a and 3b are two perspective views of a comparative screw according to prior art CN103047345A, and figures 3c and 3d demonstrate comparative inventive features;

fig. 4 illustrates an example of a tool received in a screw head.

Detailed Description

Fig. 1 illustrates an exemplary screw, which is explained in more detail below. The screw 1 comprises a screw head 2 at a first end 1a of the screw 1 and a shank 3 extending from the screw head 2 towards an opposite second end 1b of the screw 1. A thread 5 is provided on the shank 3 to screw the screw 1 into the material by means of a fixing tool.

For a fastening tool, the screw head 2 comprises a tool receiver 4, such as for exampleSix balls (Hexalobular) as exemplified in FIG. 4A socket for engaging a corresponding fixing tool to screw in the screw 1.

Alternatively, the screw 1 comprises a cut 9 in the thread 5 to make it easier for the screw 1 to cut a way into the material. The cut 9 extends along the shaft 3 and has a sharp edge, for example extending over seven turns of the thread. The incisions 9 may extend over fewer or more turns.

Alternatively, the screw 1 comprises a knurled shoulder 10 to reduce resistance when the screw 1 is driven into a material, for example wood. The knurled shoulder 10 has an outer diameter greater than the diameter of the shank 3 near the screw head 2 so as to create a wider bore than the shank 3. Typically, a knurled shoulder 10 is provided in immediate extension of the thread 5.

Fig. 2 illustrates the screw head 2 in various perspective views. Fig. 2a is a side view of the screw head 2, fig. 2b is a different side view of the underside 2b of the screw head 2 viewed in a direction parallel to the screw axis 6, fig. 2c is a different side view, and fig. 2d to 2f are different perspective views of the underside of the screw head.

A plurality of milled ribs 8 are provided on the tapered surface 7 on the underside 2b of the screw head 2. The milled ribs 8 are inclined relative to a plane parallel to the screw axis 6 to press the material inwards towards the shank 3 during the counter-boring of the screw head 2.

The typical number of milling ribs is 3-8, for example, 6 milling ribs 8 as illustrated. For example, the milling ribs 8 are arranged at the same mutual angular distance. The angular distance is 60 deg. for the 6 ribs of the example.

The underside 2b of the screw head 2 is provided with a tapering surface 7 which tapers inwardly towards the shank 3, wherein the tapering direction 19 is in a plane containing the central axis 6. Typically, the complete angle spanned by the tapered surfaces when projected onto the drawing plane (which also includes the central axis 6) is in the range 40-120, for example 60.

Figures 3c and 3d demonstrate certain features of the screw head 2 and ribs 8 compared to a comparative screw head 2' from prior art document CN103047245A and shown in figures 3a and 3 b.

In contrast, when comparing fig. 3a and 3b of the prior art with fig. 3c and 3d of the present invention and fig. 2 (especially fig. 2f), the following observations are made.

The rib C9 of the comparative screw extends to the periphery of the screw head, while the rib 8 of FIG. 3C does not. As is also shown in detail in fig. 3c, the milling rib 8 ends in a circle 20, the diameter of which is smaller than the diameter of the screw head 2 at its periphery 12. This allows a flat edge area 11 between the circumference 12 and the circle 20 on the lower side of the screw head 2, which is opposite to the upper side with the tool receiver 4. The flat edge region 11 of the peripheral edge 12 comprises a cutting edge 13 which cuts off wood fibers when the screw head 2 is countersunk into wood, for example. The cutting edge 13 creates a clean cutting edge for the counter bore of the screw head 2. The flat edge region 11 extends along the circumference 12 of the screw head 2 in a circle around all milling ribs 8. In contrast, the comparative screw did not have a flat edge region extending in a circle around it, but merely provided sections C11, which were located between the milled ribs C9. These sections do not have the same effect as a circular flat edge region with a circular cutting edge 13.

The milling edge C2 of the milling rib C9 of the comparative screw of fig. 3a and 3b curves along a concave curve, the front side 15 of the milling rib 8 being a straight plane, so that the milling edge 17 of fig. 3C and 3d follows a curve in a straight plane. The trailing edge 17' of the milled rib 8 is in a plane parallel to the plane of the flat leading side 15, as exemplified by the two parallel lines C7 and C8 of fig. 3. The milling edge (8) has a constant width.

The pockets between the ribs of the comparative screws of fig. 3a and 3b follow a conical surface and are thus convex (see also the indicator lines C5 and C6), and the pockets 14 of fig. 3C and 3d are concave. They curve smoothly inward from one bead to the adjacent bead. Further, the recess follows a concave curve, exemplified by curve C3 of fig. 3C, at the periphery of the screw head in a plane perpendicular to axis 6. Due to the recessed pocket 14 on the underside of the head 2, as exemplified in fig. 2f and 3c, the area under the head 1 is larger than for a comparative screw, which increases the grip in the material (e.g. wood, composite or polymer) when counter bored.

Perpendicular to the plane perpendicular to the central axis 6, the recess 14 follows a concave curve C3 near the peripheral edge 12 and follows an convex curve C4 at the stem 3, as exemplified in fig. 3C. However, the recess 14 itself is concave between the curves C3 and C4 and thus curves inwardly into the screw head 2.

List of labels:

1 screw

1a first end (of a screw)

1b (of the screw)

2 screw head

2a upper side (of the screw head)

2b (of the screw head)

3 handle

4 (in the screw head) tool receiver

5 (on the shank) screw thread

6 central axis

7 tapered surface

8 milling rib

9 incision

10 knurled shoulder

11 (along the periphery) flat edge region

12 (of the screw head) periphery

13 (at the periphery) cutting edge

14 (between milling ribs) pockets

15 (of the milling ribs) front side

17, 17' milling edge

19 (towards the shank) direction of taper

20 (with ribs milled inside).