screw connection

Abstract

A screw connection (1) for joining at least two workpieces (2, 3, 4, 5) comprises a screw (10) that passes through at least one of the workpieces (2, 3, 4, 5) and has a screw head (11), a cylindrical dowel pin (12) in a contact area of ​​the at least two workpieces (2, 3, 4, 5), and a threaded section (13), wherein a nut (7) is screwed onto the threaded section (13), the screw head (11) being designed as a conical countersunk head that is received in a conical recess (8) in at least one of the workpieces (2, 3, 4, 5). The screw connection (1) allows at least two workpieces (2, 3, 4, 5) to be fixed to one another with high precision and strength.

Description

[0001] The present invention relates to a screw connection for connecting at least two workpieces with a screw which passes through at least one of the workpieces and has a screw head, a cylindrical dowel pin in a contact area of ​​the at least two workpieces and a threaded section, wherein a nut is screwed onto the threaded section.

[0002] For fixing elements in steel and plant construction, fitted bolts are commonly used. These bolts incorporate a dowel pin to precisely fix workpieces to one another. Such fitted bolts typically have a cylindrical head and a threaded section and are designed to withstand shear stresses. The bolt head usually protrudes beyond the workpiece, which is disadvantageous when a bolted sheet metal surface is to be covered with seals or asphalt layers where the bolt head would be an obstruction. Especially in bridge rehabilitation, there is a need for optimized bolted connections.

[0003] It is therefore an object of the present invention to provide a screw connection by means of which workpieces can be fixed to each other with high strength and precision in a compact design.

[0004] This problem is solved by a screw connection having the features of claim 1.

[0005] The screw connection according to the invention for joining at least two workpieces comprises a screw that passes through at least one of the workpieces and has a screw head, a cylindrical dowel pin in a contact area between the at least two workpieces, and a threaded section, wherein a nut is screwed onto the threaded section and the screw head is designed as a conical countersunk head that is received in a conical recess in at least one of the workpieces. By combining a dowel pin with a conical countersunk head, the screw can, on the one hand, ensure precise positioning of the at least two workpieces and, on the other hand, guarantee a stable connection in a contact area between the at least two workpieces, while, on the other hand, a protruding screw head is partially or completely avoided by means of the countersunk head.This allows a coating, such as a sealant or an asphalt layer, to be applied to the surface side with the screw head in an improved manner.

[0006] In a preferred embodiment, the conical recess for the countersunk head extends over at least one workpiece, for example, one, two, or three workpieces. This allows the at least one workpiece to be centered and positioned over the screw in the area of ​​the countersunk head. The recess for the countersunk head can also extend through several workpieces, so that thin materials, such as metal sheets, can also be used in the head area. The conical countersunk head preferably expands at an angle of between 80° and 100° to the axial direction, particularly between 85° and 95°. The countersunk head can be arranged completely within the recess in the at least one workpiece, with one upper surface of the screw head preferably being flush with a surface of the outer workpiece.

[0007] A notch is preferably arranged between the dowel pin and the threaded section of the screw. This notch is located at least partially, and preferably completely, within the workpiece and / or a washer. The annular notch forms a transition between the dowel pin and the threaded section and therefore cannot be used to secure the nut. If the screw is positioned in the clamping assembly such that the notch is located within the workpiece, a washer according to DIN EN 14399-6-2015-4 is used. If the screw is positioned in the clamping assembly such that the notch is located outside the workpiece, a washer is arranged around this notch. This washer has, for example, an axial length between 3 mm and 20 mm. The washer can be a high-strength (HV) washer according to DIN EN 14399-6-2015-4 or manufactured with a custom thickness and is preferably made of metal. The nut can be designed according to DIN EN 14399-4:2015-04.This means that, contrary to DIN EN 14399-7, the screws are combined with a nut, in particular a high-strength nut, and a high-strength washer.

[0008] The dowel pin extends through at least one adjacent workpiece, with the bore for the dowel pin being manufactured to a tight tolerance. The bore in the at least one workpiece preferably has a bore tolerance of H11 or lower according to ISO 286-1-2019. The dowel pin of the screw can be manufactured with a tight tolerance in accordance with DIN EN 14399-8 to prevent relative movement between the workpieces. The connection of the workpieces in the area of ​​the dowel pin and the screw head is subjected to shear stress and is therefore classified as Category A according to DIN EN 1993-1-8. To reduce deformation and increase fatigue strength, the screw is nevertheless preloaded via the nut. For this purpose, preload must be applied, but not according to the "modified preload method (mDMV)" or "combined preload method (KVV)" according to DIN EN 1090-2.

[0009] In a preferred embodiment, at least one of the workpieces is designed as a bridge deck plate or main load-bearing element. Such connection combinations are used, for example, in bridge rehabilitation and are coated after assembly. For corrosion protection, the finished bolted connection can be coated with a primer before a road surface or a sealing structure is applied.

[0010] For efficient manufacturing, the recess for the countersunk head and the bore in the at least two workpieces can be produced using a single drilling tool. Such a drilling tool preferably comprises a cylindrical section for producing the cylindrical bore and a conical section for producing the conical recess in at least one of the workpieces.

[0011] The screw head preferably has a slotted recess for a tool. This allows the screw head to be held in place by the slotted recess when the nut is tightened to a predetermined torque. The slotted recess preferably extends only in an upper region of the screw head and is surrounded on all sides by an edge of the conical countersunk head.

[0012] The invention is explained in more detail below with reference to an exemplary embodiment and the accompanying drawings. These show: Fig. 1 a sectional view through a screw connection according to the invention, and Fig. 2A to 2C several views of the screw of the screw connection of the Fig. 1.

[0013] A screw connection 1 serves to connect several workpieces 2, 3, 4, and 5, for example, different metal sheets, which are in contact with each other at least in the area of ​​the screw connection 1. Such plate-shaped workpieces 2, 3, 4, 5 can, for example, be part of a load-bearing structure, such as for supporting a roadway on a bridge, or serve other purposes. The workpieces 2, 3, 4, 5 preferably comprise a bridge roadway and, for example, a steel sheet or a steel beam. A plurality of screw connections 1 can be provided to fix the workpieces 2, 3, 4, 5 to one another.

[0014] A screw 10 passes through workpieces 2, 3, 4, and 5 and includes a screw head 11, which is designed as a countersunk head and widens conically towards a surface. A dowel pin 12 is attached to the screw head 11, passing through the bore of at least two of the workpieces 3, 4, and 5 and connecting to a threaded section 13 via a notch 14. A nut 7 is screwed onto the threaded section 13, with a metal washer 6 in the form of a high-strength (HV) washer being positioned between the nut 7 and the workpiece 5 facing the nut 7. Optionally, the washer 6 can also be designed as a wedge-locking washer.

[0015] The countersunk head of the screw head 11 expands by an angle α, preferably between 80° and 100°, particularly between 85° and 95°. The screw head 11 has a slot-shaped receptacle 16 which also expands at an angle to the axial direction of the screw 10 on opposite sides, for example also by the angle α.

[0016] The workpiece 2 is positioned in the area of ​​the screw head 11, with a contact area between workpieces 2 and 3, extending perpendicular to the axial direction of the screw 10, located in the area of ​​the conical expansion of the screw head 11. Accordingly, a conical receptacle 8 for the screw head 11 is formed in workpiece 2 and, to a lesser extent, also in workpiece 3. Optionally, the conical receptacle 8 can be located in only a single workpiece 2 or in more than two workpieces 2 and 3. Likewise, the number and thickness of the workpieces and clamping assemblies can vary as desired.

[0017] The cylindrical dowel pin 12 extends through three workpieces 3, 4, and 5 and can position them precisely and accurately. In its assembled position, the dowel pin 12 is subjected to shear stress (high-strength shear connection), thus ensuring the exact positioning of the three workpieces 3, 4, and 5. Optionally, the dowel pin 12 can pass through only two workpieces 4 and 5 or through more than three workpieces 3, 4, and 5. Also optionally, it can be subjected to tensile stress or a combined tensile and shear stress. The screw connection can also be used when there are no requirements for force transmission through a fit. In this case, the screw connection would act as a shear-bearing connection (high-strength connection). The hole clearance must comply with the requirements of DIN EN 1090-2.

[0018] The transition between the dowel pin 12 and the threaded section 13 is formed by a notch 14, which serves no function with regard to the connection. Therefore, the notch 14 is only partially located within the workpiece 5, preferably less than 50% within the workpiece 5. When subjected to shear stress in a precision fit, the dowel pin 12 must lie within the force-transmitting shear plane. In the area of ​​the washer 6, only axial forces are transmitted between the threaded section and the screw head 11. The nut 7 must therefore be screwed onto the threaded section 13 along its entire axial length, and a thread projection of at least one thread length must be present before any preload force is applied.

[0019] An outer surface of the screw head 11 is essentially flush with a surface of the workpiece 2, so that no protruding parts are present in the assembled position of the screw connection 1. The screw head 11 is preferably arranged completely within the conical recess 8, preferably countersunk to a depth of 0.5 mm. The screw connection 1 can be coated on the surface of the workpiece 2 and the screw head 11, for example with a primer to prevent corrosion, in order to then apply a sealant or a road surface to this side.

[0020] In the Fig.Figures 2A to 2C show screw 10 in detail. Screw 10 can, for example, have a length between 60 mm and 200 mm, with the total length L4 being divided among the different sections of screw 10. The screw head 11 has an axial length L1 of, for example, 10 mm to 25 mm, and the axial length of the screw head 11 together with the dowel pin L2 is, for example, between 30 mm and 90 mm. The groove 14 has an axial length between 5 mm and 15 mm, resulting in the corresponding length L3.

[0021] The threaded section 13 of the screw 10 can, for example, be a standardized thread M12 to M56, preferably between M16 and M36.

[0022] The slot-shaped recess 16 on the outside of the screw head 11 preferably does not extend over the entire diameter of the screw head, which may, for example, be between 40 mm and 60 mm. The length of the slot-shaped recess 16 is at least 10% shorter than the diameter. The depth of the slot-shaped recess 16 may, for example, be between 3 mm and 8 mm. Reference symbol list 1 screw connection 2 workpieces 3 workpieces 4 workpieces 5 workpieces 6 washers 7 Mother 8 conical intake 10 screws 11 screw head 12 dowel pins 13 Thread section 14 notches 16 slot-shaped inlets α angle L1 length L2 length L3 length L4 Total length 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 non-patent literature

[0000] DIN EN 14399-6-2015-4

[0007]

Claims

[1] Screw connection (1) for connecting at least two workpieces (2, 3, 4, 5) with a screw (10) which passes through at least one of the workpieces (2, 3, 4, 5) and has a screw head (11), a cylindrical dowel pin (12) in a contact area of ​​the at least two workpieces (2, 3, 4, 5) and a threaded section (13), wherein a nut (7) is screwed onto the threaded section (13), characterized by , that the screw head (11) is designed as a conical countersunk head which is received into a conical recess (8) in at least one of the workpieces (2, 3, 4, 5). [2] Screw connection according to claim 1, characterized by , that the conical recess (8) for the countersunk head extends over at least one workpiece (2, 3). [3] Screw connection according to claim 1 or 2, characterized by , that the conical countersunk head spreads out at an angle between 80° and 100° to the axial direction, in particular between 85° and 95°. [4] Screw connection according to one of the preceding claims, characterized by , that a notch (14) is arranged between the dowel pin (12) and a threaded section (13) of the screw (10), which is arranged within the at least one workpiece (2, 3, 4, 5) and / or within a washer (6). [5] Screw connection according to claim 4, characterized by , that the washer (6) has an axial extent between 3 mm and 20 mm. [6] Screw connection according to claim 4 or 5, characterized by , that the washer (6) is arranged between the nut (7) and the workpiece (5) facing the nut (7) and is designed as an HV washer according to DIN EN 14399-6-2015-4. [7] Screw connection according to one of the preceding claims, characterized by , that the dowel pin (12) passes through at least two adjacent workpieces (4, 5). [8] Screw connection according to one of the preceding claims, characterized by, that one of the workpieces (2, 3, 4, 5) is designed as a bridge deck. [9] Screw connection according to one of the preceding claims, characterized by , that a bore in the at least one workpiece (2, 3, 4, 5) is formed with a bore tolerance of H11 according to ISO 286-1-2019. [10] Screw connection according to one of the preceding claims, characterized by , that the recess (8) for the countersunk head and the bore in the at least two workpieces (2, 3, 4, 5) are produced by a single drilling tool. [11] Screw connection according to one of the preceding claims, characterized by , that the screw head (11) has a slotted receptacle (16) for a tool.

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