Self-drilling screw, a component bond with this screw, and the use of this screw

Abstract

Self-drilling screw (1) consisting of a screw head (3) and a screw shank (5), at the end of which opposite the screw head (3) a drill tip (7) is arranged and a thread (51, 57) extends at least partially on the screw shank (5) and the drill tip (7) has a helically extending flute (60), characterized in that the flute (60) is extended beyond the shank end of the drill tip (7) into the primary thread (57).

Description

[0001] The invention relates to a self-drilling screw, a component assembly with this screw, and the use of this screw. STATE OF THE ART

[0002] Self-drilling screws are used when pre-drilling the mounting point is to be avoided.

[0003] There are a wide variety of applications, each requiring specific properties from the screws used. The use of screws in component assemblies presents requirements relating to both the material of the components and the type of connection.

[0004] When two workpieces made of different materials are to be joined together, this places higher demands on the screws used. In addition, there are situations where the screws must have special corrosion resistance.

[0005] When machining assemblies, a common problem is that the components lift apart when the drill bit and thread engage. This can result in chips not being removed quickly enough. If the drill bit overheats as a result, it becomes dull and loses its drilling performance.

[0006] If there is an increased risk of corrosion depending on the application and operating conditions, then special material requirements apply to the screw, which must then be made of stainless steel, for example. The drill tip, made of hardenable carbon steel, is then joined to the stainless steel shaft of the screw in a separate manufacturing step.

[0007] EP 2 092 995 B1 describes a screw whose shank end, opposite the screw head, is designed as a drilled section. The screw is manufactured in one piece from forgeable and hardenable carbon steel, which must be coated in a separate step to protect against corrosion. The drilled section is created by twisting the shank, which is inserted into a clamping device. Grooves are first machined into the drilled section, and after twisting, these grooves are twisted into a helical shape. However, creating a drilled section by twisting the screw shank offers limited design options for its geometry. In particular, this does not allow for individual shaping of the wedge, rake, or helix angles. An unbalanced ratio of angular geometries directly affects the cutting performance and chip evacuation of the screw. TASK STATEMENT

[0008] The present invention is based on the objective of providing a screw, and thus a fastening arrangement and a use of the screw, which eliminates the disadvantages of the known screws.

[0009] This problem is solved by the independent claims. Advantageous embodiments of the invention are specified in the dependent claims. ADVANTAGES OF THE INVENTION

[0010] According to the invention, a self-drilling screw is proposed, consisting of a screw head and a screw shaft, at the end of which opposite the screw head a drill tip is arranged and a thread extends at least partially on the screw shaft and the drill tip has a helically extending flute.

[0011] The invention is characterized in that the flute is extended into the primary thread beyond the shaft-side end of the drill tip.

[0012] This ensures chip removal even at the transition area to the primary thread.

[0013] A particular advantage of the invention is that the self-drilling screw according to the invention has the properties of a spiral drill bit, but with more efficient drilling behavior and improved chip removal.

[0014] It has proven particularly advantageous if the flute extends from the drill tip over at least the lowest thread notch of the primary thread. Further optimization, in conjunction with the drill tip's angular geometry, occurs when the flute extends at least 10 mm into the primary thread. Compared to a conventional twist drill, the wedge angle is significantly reduced. This allows for a larger rake angle. This increased rake angle geometry promotes rapid chip removal from the borehole, thus preventing clogging of the drill channel, especially when drilling material combinations such as wood and aluminum. A blockage during drilling is virtually eliminated.

[0015] The invention advantageously provides that the helix angle of the drill tip is relatively steep compared to conventional twist drills, at approximately 30°, and the adjacent point angle is approximately 116°, thereby further optimizing chip removal and facilitating penetration into hard materials. This angle ratio is complemented by the specified size of the chisel edge angle, which, at approximately 80°, results in optimized cutting performance.

[0016] The modified angle geometry has resulted in optimal drilling performance. The drill bit is self-centering and cuts cleanly through wood and metal. Axial forces are reduced, resulting in less material deformation.

[0017] By using a coarse thread in the base body, this eliminates the need for additional drilling before assembly.

[0018] The invention provides that the screw shank is divided into shank sections, consisting of a shank neck with a threaded underside of the screw head, a threadless shank section extending from the shank neck towards the drill tip, and a shank base with the primary thread located between the threadless shank section and the drill tip. This division into individual functional sections facilitates the trouble-free penetration of different materials.

[0019] The invention further provides that the shaft base is penetrated by a scraping groove extending parallel to the longitudinal axis of the screw, which intersects the primary thread.

[0020] Preferably, the scraper groove extends from near the end of the chip groove towards the screw head. The scraper groove improves chip removal and ensures quick and easy screw insertion. Furthermore, the scraper groove reduces the risk of the wood splitting and minimizes cracking.

[0021] The screw can be manufactured from virtually all metallic materials and material combinations. It is preferably made of hardenable carbon steel, so that the screw head, screw shank, and drill tip are manufactured as a single piece. The drill tip can be hardened and heat-treated. In a particularly preferred embodiment of the invention, it is provided that the screw is designed as a bi-metal screw, wherein the screw head and the adjoining screw shank are made of stainless steel, and the drill tip is made of hardenable carbon steel, which is welded to the stainless steel screw shank above it. However, bi-metal combinations of two types of carbon steel are also possible.

[0022] The bi-metal design of this screw offers numerous advantages. The body, for example, can be made of A2 stainless steel, exhibiting high corrosion resistance and strong resistance to tannins, significantly expanding its range of applications. The stainless steel body ensures the screw's long-term corrosion resistance. The drill tip, made of carbon steel, is hardenable, providing high cutting performance. This tip retains its sharpness and can drill even harder materials, such as 8mm steel, without the need for pre-drilling. This translates into significant time savings during assembly. Furthermore, the screw itself is permanently corrosion-resistant. The body of the bi-metal screw thus combines the best properties of the steel grades used.

[0023] A component assembly according to the dependent claim comprises at least two components to be joined together, consisting of a crossbeam and a connecting beam to be mounted orthogonally to it and a t-shaped mounting rail which is screwed to the crossbeam using at least two self-drilling screws passing through the connecting beam and the mounting rail according to one of the claims preceding the dependent claim of this screw.

[0024] The design provides that the T-shaped mounting rail has a flange and a web, with the flange being attached to the crossbeam and the web extending coaxially to the connecting beam.

[0025] The connecting beam has a bed on its end face and a slot extending orthogonally from it for the recessed reception of the t-shaped mounting rail.

[0026] The depth of the bed is at least equal to the thickness of the flange, and the width of the bed is equal to the width of the flange, while the depth of the slot is at least equal to the height of the web. Thus, the connecting beam is prepared in such a way that it completely conceals the mounting rail.

[0027] To facilitate easy assembly of the connecting beam to the crossbeam, the invention provides that both the bed and the slot extend through the connecting beam, entering it on its underside and exiting on its top side. This allows the connecting beam to be either slid onto the crossbeam along its longitudinal axis or inserted from above.

[0028] According to the invention, the proposed screw is suitable for use in connecting at least two components, wherein at least one component is made of wood and another component or assembly aid, in particular a mounting rail, is made of metal, since the screw is self-drilling and can be used for wood, aluminum and steel due to the drill tip and thread geometry.

[0029] Further advantages and advantageous embodiments of the invention can be found in the following description, the drawings, and the claims. There are various ways to advantageously develop and further refine the teaching of the present invention. For this purpose, reference should be made, on the one hand, to the dependent claims and, on the other hand, to the following explanation of an exemplary embodiment of the invention with reference to the drawing. EXAMPLE OF EXECUTION

[0030] In conjunction with the explanation of the preferred embodiment of the invention with reference to the drawings, generally preferred embodiments and further developments of the teaching are also explained.

[0031] The drawings show: Fig. 1 the screw according to the invention in a side view, Fig. 2 the screw according to the invention from the in Fig. 3 arrow direction marked with II, Fig. 3 a top view of the screw from the in Fig. 1 arrow direction marked with III, Fig. 4 a view of the screw from the in Fig. 1 arrow direction marked with IV, Fig. 5 that in Fig. 2 Detail of the drill bit marked with V in an enlarged view, Fig. 6 the drill bit from the in Fig. 3 arrow direction marked with VI, Fig. 7 the drill bit from the in Fig. 3 arrow direction marked with VII, Fig. 8 the view of the screw as in Fig. 4 shown in an enlarged view, Fig. 9. View of the screw as shown in Fig. 5 shown in an enlarged view, Fig. 10 a sectional view along the in Fig. 9 indicated line XX, Fig. 11 a schematic representation of chip removal, Fig. 12 the screw according to the invention in a further side view, Fig. 13 the in Fig. 12 Detail of the drill bit marked XIII in an enlarged view, Fig. 14 a view of the drill bit from the in Fig. 13 marked direction XIV, Fig. 15 the application of the screw according to the invention, Fig. 16 a perspective view of a prepared connecting beam, Fig. 17 a side view of the in Fig. 16 illustrated connecting beams, Fig. 18 a front view of the connecting beam from the in Fig. 17 arrow direction marked with XIIX, Fig. 19 a top view of the connecting beam from the in Fig. 17 arrow direction marked XIX, Fig. 20 a side view of a mounting rail, Fig. 21 the mounting rail in a top view from the in Fig. 20 displayed arrow direction XXI, Fig. 22 the mounting rail in a bottom view from the in Fig. 20 indicated arrow direction XXII, Fig. 23 the mounting rail in a front view from the in Fig. 20 indicated arrow direction XXIII and Fig. 24 the mounting rail screwed to a crossbeam.

[0032] The screw, designated as a whole by 1, has a screw head 3 and a screw shaft 5, which in turn is divided into individual sections, as well as a drill tip 7.

[0033] The shank sections are a shank neck 50 with a bottom thread 51, located directly below the screw head 3. This is followed towards the drill tip 7 by a threadless shank section 53 and a shank base 55 with a primary thread 57, located between the threadless shank section 53 and the drill tip 7. A frustoconical shoulder 52 connects the threadless shank section 53 to the shank neck 50, and a frustoconical shoulder 54 connects it to the shank base 55. The outer diameter d1 of the threadless shank section 53 is larger than the adjacent core diameter d2 of the shank neck 50 and the core diameter d3 of the shank base 55.

[0034] A scraper groove 58 running parallel to the longitudinal axis 2 of the screw is arranged on the shaft base 55 ( Fig. 6, Fig. 11 and Fig. 12), which penetrates the thread flanks 59 in the longitudinal direction of the primary thread 57 and extends over the thread pitch, or in this case, approximately over eight thread notches 62. A thread notch 62 is defined by the pitch.

[0035] The drill tip 7, which adjoins the shaft base 55, has approximately the geometry of a twist drill. Compared to a classic twist drill, the helix angle α ( Fig. 13) executed at a steeper angle. Here at approximately 30°. The tip angle ε, which communicates with the helix angle α, complements this at approximately 116°, contributing to the significant drilling performance. In Fig. Figure 14 shows that, compared to a conventional spiral drill, the wedge angle β is also significantly reduced, which allows for an increase in the rake angle γ.

[0036] The angular geometry according to the invention is completed by the specified transverse cutting angle 2 between the main cutting edge 65 and the transverse cutting edge 67. (See Fig. 8)

[0037] A chip groove 60 runs through the drill tip 7 and extends into the primary thread 57 from the end of the drill tip 7 near the primary thread 57. An extension of at least 10 mm into the primary thread 57 has proven particularly advantageous here to ensure chip removal even in the transition area to the primary thread 57. Both the primary thread 57 and the underhead thread 51 running on the shank neck 50 are designed as coarse threads.

[0038] In Fig. Figure 11 shows the chip removal schematically and shows a wooden profile 99 arranged over an aluminum profile 98, both of which are drilled through and how the chips 97 are removed from both sides.

[0039] According to the invention, the angular geometry and thus the relationships between them were optimized. In particular, in the Fig. Figures 9 to 14 illustrate the angular relationships according to the invention. Compared to a conventional twist drill, the drill tip 7 has a significantly reduced wedge angle β in order to increase the rake angle γ. Likewise, the helix angle α has a steeper profile compared to a conventional twist drill. The remaining clearance angle is designated by the reference numeral δ. Here, a value of approximately 13° has proven to be significantly advantageous. The optimized angular geometry improves both the screw-in and drilling performance, as well as chip removal. The increased rake angle geometry promotes the rapid removal of chips from the borehole and prevents clogging of the borehole channel, particularly in material combinations of wood and aluminum. The steeper design of the helix angle α optimizes the removal of the chips 97 ( Fig. 11) and facilitates penetration into hard materials. The extension of the chip groove 60 into the area of ​​the primary thread 57 ensures chip removal even in the transition area to the primary thread 57.

[0040] The milled scraper groove 58 reduces the splitting force of the screw 1 in the wood, especially when the screw 1 is used in the area near the edge.

[0041] The Fig. Figure 15 shows the application of screw 1 according to the invention. Here, a connecting beam 100 is attached to a crossbeam 102. For this connection, the screw 1 is used in the Fig. Mounting rail 105 shown in 20 to 23 is required, which is attached to the crossbeam 102 with wood screws 110 ( Fig. 15).

[0042] The one in the Fig. The connecting bar 100 shown in figures 16 to 19 is prepared accordingly for adaptation.

[0043] The mounting rail 105 ( Fig. 20-23) is a T-profile with a web 106 and a flange 107 oriented orthogonally to the web 106, extending over the web on both sides. The flange 107 is perforated with holes 109 on both sides of the web 106 to allow the mounting rail 105 to be attached with screws 110 (see Fig. 24) to attach to the crossbeam 102.

[0044] In the connecting beam 100 ( Fig. 16-19) A bed 115 on the end face and a slot 117 extending longitudinally along the connecting beam 100 are milled. The bed 115 and the slot 117 together form a receptacle that approximately corresponds to the cross-section of the T-shaped mounting rail 105, wherein the depth “t” of the bed 115 is at least equal to the thickness “f” of the flange 107 of the mounting rail 105. The width “b” of the slot 117 corresponds to the thickness “s” of the web 106 of the mounting rail 105. The depth “Ti” of the slot 117 is preferably chosen to be slightly greater than the height “h” of the web 106 of the mounting rail 105. After the mounting rail 105 has been screwed to the crossbeam 102 ( Fig.15) The connecting beam 100, prepared as described above, can be adapted to the crossbeam 102 by bringing the connecting beam 100 towards the crossbeam 102 in such a way that the mounting rail 105 with its web 106 is inserted into the slot 117. The bed 115 then surrounds the flange 107 of the mounting rail 105. Once the final position of both components relative to each other is fixed, the screws 1 according to the invention are driven into the side wall 101 of the connecting beam 100. The screws 1 first penetrate the wooden material of the connecting beam 100 and then encounter the metal mounting rail 105 before again encountering the wooden material of the adjacent side wall 101a of the connecting beam 100.The properties of screw 1 according to the invention ensure that both different materials are penetrated and that their differing chip formation is taken into account by the geometry of the screw thread and the drill tip. This optimizes chip removal, which in turn significantly improves the screw-in behavior. REFERENCE MARK LIST 1 screw 2 screw longitudinal axis 3 heads out of 1 5 shaft of 1 7 drill bits from 1 31 internal drive of 3 50 shaft necks 51 Underhead threads on 50 Paragraph 52 between 50 and 53 53 threadless shaft section of 5 Paragraph 54 between 53 and 55 55 shaft foot of 5 57 Primary thread on 55 58 cockroaches on 55 59 thread flanks of 57 60 Spannut 62 thread notches 65 Main cutting edge 67 Cross-cutting edge 97 shavings 98 Aluminum profile 99 wood profile 100 connecting beams 100a Underside of 100 100b Top side of 100 101 side wall of 100 101a Side wall of 100 102 crossbeams 105 Mounting rail 106 Bridge of 105 107 flange of 105 109 holes in 107 110 wood screws 115 end-facing bed in 100 117 slots in 100 d1 outer diameter of 53 d2 core diameter of 50 d3 core diameter of 55 α Twist angle β Wedge angle γ rake angle δ Free angle ε Apex angle Cross-cutting angle depth of 115 f thickness of 107 b Width of 117 Ti depth of 117 h height of 106 s strength of 106 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2 092 995 B1

[0007]

Claims

[1] Self-drilling screw (1) consisting of a screw head (3) and a screw shank (5), at the end of which opposite the screw head (3) a drill tip (7) is arranged and a thread (51, 57) extends at least partially on the screw shank (5) and the drill tip (7) has a helically extending flute (60), characterized by , that the flute (60) extends beyond the shaft-side end of the drill tip (7) into the primary thread (57). [2] Self-drilling screw (1) according to claim 1, characterized by , that the flute (60) extends from the drill tip (7) over at least the lowest thread notch (62) of the primary thread (57). [3] Self-drilling screw (1) according to claim 1, characterized by , that the flute (60) extends from the drill tip (7) at least 10 mm into the primary thread (57). [4] Self-drilling screw (1) according to claim 1, characterized by, that the helix angle (α) of the drill tip (7) is approximately 30°. [5] Self-drilling screw (1) according to claim 1, characterized by , that the tip angle (ε) of the drill tip (7) is approximately 116°. [6] Self-drilling screw (1) according to claim 1, characterized by , that the cross-cutting angle (2) is approximately 80°. [7] Self-drilling screw (1) according to claim 1, characterized by , that the screw shank (5) is divided into shank sections, consisting of a shank neck (50) adjoining below the screw head (3) with an underhead thread (51), a shank unthreaded section (53) following the shank neck towards the drill tip (7) and a shank base (55) with the primary thread (57) arranged between the shank unthreaded section (53) and the drill tip (7). [8] Self-drilling screw (1) according to claim 7, characterized by, that the shaft base (55) is penetrated by a scraping groove (58) extending parallel to the longitudinal axis (2) of the screw, which intersects the primary thread (57). [9] Self-drilling screw (1) according to claim 8, characterized by , that the scraper groove (58) extends from near the end of the clamping groove (60) towards the screw head (3). [10] Self-drilling screw (1) according to claim 1 and 2, characterized by , that an underhead thread (51) is arranged on the shaft neck (50). [11] Self-drilling screw (1) according to claims 1 to 10, characterized by , that the screw head (3) and the screw shaft (5) adjoining it are made of stainless steel and the drill tip (7) is made of hardenable carbon steel, which is welded to the screw shaft (5) above it made of stainless steel. [12] Component assembly comprising at least two components to be joined together, consisting of a crossbeam (102) and a connecting beam (100) to be mounted orthogonally to it and a t-shaped mounting rail (105) which is screwed to the crossbeam (102) using at least two self-drilling screws (1) passing through the connecting beam (100) and the mounting rail (105) according to one of the preceding claims. [13] Component composite according to claim 12, characterized by , that the t-shaped mounting rail (105) has a flange (107) and a web (106), wherein the flange (107) is attached to the crossbeam (102) and the web (106) extends coaxially to the connecting beam (100). [14] Component assembly according to claims 12 and 13, characterized by , that the connecting beam (100) has a bed (115) on its end face and a slot (117) extending orthogonally from it for the recessed reception of the t-shaped mounting rail (105). [15] Component assembly according to claims 13 and 14, characterized by , that the depth (t) of the bed (115) is at least equal to the thickness (f) of the flange (107) and the width of the bed (115) is equal to the width of the flange (107). [16] Component assembly according to claims 12 to 15, characterized by that the depth (T i ) of the slot (117) corresponds at least to the height (h) of the bridge (106). [17] Component assembly according to claims 12 to 16, characterized by , that both the bed (115) and the slot (117) penetrate the connecting beam (100) and enter the connecting beam (100) on its underside (101a) and exit on its top side (100b). [18] Use of a self-drilling screw (1) according to one of claims 1 to 11 for connecting at least two components according to one of claims 12 to 17, wherein at least one component is made of wood and another component or assembly aid, in particular a mounting rail (105), is made of metal.

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