Screw nut with a base body and a threaded bore

Description

[0001] The invention relates to a screw nut with a base body and a positioning cone connected to the base body, the positioning cone having a threaded bore and an opening opening into the threaded bore and tapering towards the base body, wherein the positioning cone has a striking edge at its free end section for driving into a workpiece, which limits the opening (8).

[0002] Such a screw nut is disclosed in US 2307080 A.

[0003] Prior art discloses screw nuts comprising a prismatic base body, for example, DE202011001662U1. This base body has a threaded bore along its height into which a fastener with a matching thread, such as a screw or bolt, can be inserted by tightening. A tool can be applied to the outer edges of the prismatic base body to create the screw connection by applying torque, thereby bringing the screw nut and fastener closer together along the screw axis and creating a positive or force-fit connection, and optionally clamping a workpiece between the screw nut and the fastener.

[0004] US20210404503A1 also shows a screw nut with a through threaded bore and a conical end section, with which the screw nut can be pre-positioned in a bore hole whose diameter is larger than the outer diameter of the end section.

[0005] US1787154A shows a screw nut with an internal threaded bore and a rounded positioning cone as the end section, which is placed in a receptacle of the workpiece adapted to the positioning cone.

[0006] A disadvantage of the prior art, however, is that the nut cannot be pre-positioned on a workpiece due to the design of its body. If the nut is simply placed flush with a drilled hole and the fastener is inserted from the other side, the fastener, lacking an external fixing force, pushes the nut out of position, and the nut must then be repositioned directly on the fastener. While T-nuts are known in the prior art that can be torque-supported by being driven into the workpiece, the positive locking of a T-nut in the workpiece no longer allows for the application of torque to the nut to create the screw connection.

[0007] The invention is therefore based on the objective of positioning a screw nut in alignment over a borehole of a workpiece without external positioning and holding forces, and yet being able to apply the necessary torque to the screw nut to create the screw connection.

[0008] The invention solves the stated problem by providing a stop washer extending transversely to the screw axis in the transition area between the base body and the positioning cone. The nut according to the invention can thus be positioned over the borehole of a workpiece with its positioning cone before the screw connection is made and driven into the workpiece. Due to the conical shape of the positioning cone, the nut wedges itself in the workpiece without blocking the alignment between the borehole and the threaded hole, but still allows the application of torque to create the screw connection. The force typically applied when inserting a fastener into a borehole is insufficient to push the wedged nut out of the borehole, so the positioning cone creates resistance against further insertion of the fastener.The opening of the positioning cone, which tapers towards the base body and leads into the threaded hole, serves several functions: First, it directs the applied force on the nut away from the screw axis when a fastener is inserted into a borehole, thus reducing the likelihood of the nut loosening after being driven in. Second, the wall thickness at the free end of the positioning cone is relatively thin due to the tapered opening and the impact edge, but the conical shape still provides sufficient stability, making it easier to drive into the workpiece, unlike, for example, a chamfer. Third, the tapered shape creates a guide surface for the fastener, which is thus guided to the threaded hole. This also ensures that the nut is aligned with the screw axis when the screw connection is tightened.Fourth, the opening and the resulting guide surface protect the threaded hole downstream of the screw axis from damage that can occur during insertion. Depending on the workpiece material, the striking edge can be determined by the diameter of the opening relative to the outer diameter of the end section of the positioning cone, resulting in different widths. Blunt, i.e., wide, striking edges are preferable for wooden workpieces, as they reduce the likelihood of unintentional splitting. For more brittle workpieces, however, a sharp, i.e., narrow, striking edge may be more advantageous, as it can cut into the workpiece. Depending on the workpiece material, the positioning cone can be driven into the workpiece by manual pressure or, for example, by striking the base with a hammer.If the screw nut according to the invention is used in a borehole of a workpiece that has a significantly larger diameter, so that the positioning cone does not need to be driven in, the positioning cone can only serve to pre-position the screw nut in the borehole. The base body is the part of the screw nut that forms the stop surfaces for a tool used to apply torque, for example, a wrench. The entire base body can be prismatic; however, in a preferred embodiment, the base body and the positioning cone form a common truncated cone, which only has the stop surfaces at the end section facing away from the positioning cone.

[0009] To prevent the nut according to the invention from being pulled too deeply into the workpiece during the creation of the screw connection, it is proposed that a stop washer extending transversely to the screw axis be provided in the transition area between the base body and the positioning cone. This stop washer has the same function as a washer and, by bearing flat against the workpiece, prevents further penetration beyond a certain depth. The outer contour of the stop washer transverse to the screw axis is freely selectable and has specific advantages or disadvantages depending on its shape. If, for example, it is angular, preferably square, the corners of the stop washer serve as torque support. If the outer contour is round, the nut can be driven into the workpiece, or drawn in by the fastener, particularly gently.

[0010] Although a positioning cone according to the invention can be attached to the base body, for example by welding, the screw nut according to the invention can be manufactured more easily and stably if the base body and positioning cone are made in one piece. This avoids weak points in the connection area between the base body and the positioning cone, which could lead to damage to the screw nut, especially when applying higher torques.

[0011] The nut can accommodate longer fasteners and, despite requiring less material, enable a more stable screw connection if the base body and positioning cone share a common threaded bore. This allows the fastener to be screwed into the base body through the positioning cone. As a result, forces acting on the screw connection are distributed more evenly into the nut, since the fastener penetrates the nut deeper along the screw axis, thus enabling a larger force distribution. Particularly when the positioning cone and base body are assembled from separate parts, weaknesses inherent in the connection are compensated for by the threaded connection. Because the base body also has a threaded bore, less material is required for its manufacture, even with the same external dimensions.In a preferred embodiment, the threaded bore extends through the entire nut, and the base body has a second opening, allowing the fastener to fully penetrate the nut in the direction of the screw axis or even exit it. Even if the base body and positioning cone share a common threaded bore, the threaded bore need not necessarily be threaded along its entire length.

[0012] The nut can be made particularly compact if the largest diameter of the positioning cone, perpendicular to the screw axis, does not exceed the largest diameter of the base body, also perpendicular to the screw axis. This means that the diameter of the positioning cone is less than or equal to the diameter of the base body. As a result of these measures, the dimensions of the nut can be adapted to the desired fastening method, for example, by adjusting the size of the base body to a specific wrench size.

[0013] To drive the nut into the workpiece without causing excessive damage, the striking edge, especially for workpieces made of porous or brittle materials, can have a cutting edge for driving the nut into the workpiece. This allows the force applied during driving to be transferred into the workpiece over a very small area, thus with high local pressure. The cutting edge preferably extends across the entire striking edge, ensuring that the driving force is distributed evenly into the workpiece.

[0014] To ensure that the nut can be driven sufficiently deep into the workpiece for typical applications without excessive force, while still providing adequate wedging, it is proposed that the half-opening angle of the positioning cone be between 10° and 25°, preferably 15°. If the angle is too large, the positioning cone becomes difficult to drive into the workpiece and may even split it. Conversely, if the angle is too small, the positioning cone will not wedge sufficiently. Tests have shown that angles between 10° and 25°, preferably 15°, allow for both gentle driving into the workpiece with forces typically applied to the nut and effective wedging of the positioning cone within the workpiece.

[0015] If the tightening action for creating the screw connection is applied via the fastener rather than the nut, the nut can rotate in the borehole due to the transmitted torque if it is not sufficiently wedged. To support the nut against the applied torque with this fastening method, even without external means, and thus still allow the screw connection to be created, it is proposed that longitudinal grooves be provided on the outer surface of the positioning cone to support the nut against the torque. When the positioning cone is driven into the workpiece, the longitudinal grooves increase the contact area between the positioning cone and the workpiece, thereby increasing the frictional forces.Furthermore, the longitudinal grooves not only form cutting edges for easier insertion into the workpiece, but also act as a stop for the workpiece against forces and moments acting tangentially on the positioning cone, such as the torque transmitted by a fastener during screwing. These longitudinal grooves run essentially perpendicular to the striking edge and offset by half the opening angle to the screw axis in the direction of the end section of the positioning cone adjacent to the base body. This provides support regardless of the direction of rotation of the screw. However, it is not essential that the longitudinal grooves extend over the entire length between the end sections. The longitudinal grooves can also deviate from their orthogonal course described above on a local scale, as long as this course remains orthogonal to the striking edge on a larger scale.For example, zigzag-shaped longitudinal grooves can also be provided. In principle, longitudinal ribs can also be provided instead of longitudinal grooves, since a longitudinal groove according to the invention inevitably forms between two longitudinal ribs.

[0016] Depending on the application, materials, and dimensions used, it may occur that the nut, despite being wedged in the workpiece, is not sufficiently supported against the torque applied during the bolted connection. To prevent the nut from spinning in such a case, the stop washer can incorporate at least one locking pin for torque support. This locking pin is driven into the workpiece and anchored by tightening the bolted connection, thus securing the nut against rotation. This locking pin is advantageously positioned as far as possible from the center point or the threaded hole, as a locking pin of a given size can then withstand higher torques before disengaging from its anchorage.

[0017] As an alternative to a stop washer, a washer receptacle can be provided in the transition area between the base body and the positioning cone. The largest diameter of this receptacle, perpendicular to the screw axis, is smaller than the largest diameter of the base body, also perpendicular to the screw axis. This allows the use of a washer for the nut whose size or diameter can be adapted to the components involved. Because the largest diameter of the washer receptacle, perpendicular to the screw axis, is smaller than the largest diameter of the base body, the base body acts as a stop for the washer along the screw axis. In a preferred embodiment, the washer's inner diameter and the washer receptacle are matched so that the washer can be held in place by a clamping fit in the washer receptacle.Similar to the stop washer described above, the outer contour of the washer perpendicular to the screw axis can also be freely selected.

[0018] The invention is illustrated in the drawing as an example. It shows Fig. 1 a screw nut according to the invention of a first embodiment, Fig. 2 a section along line II - II of the Fig. 1 by a screw nut according to the invention of the first embodiment as part of a screw connection with a fastening means in a workpiece and Fig. 3 one of the Fig. 2 corresponding section with a second embodiment of a screw nut according to the invention.

[0019] A screw nut according to the invention comprises a base body 1 and a positioning cone 2 connected to the base body 1. The base body 1 and the positioning cone 2 can either be manufactured separately and joined, or preferably manufactured in one piece. The positioning cone 2 has a threaded bore 3 for receiving a fastening element 4, such as a screw or a bolt. In both embodiments shown, the base body 1 also has a threaded bore that is an extension of the threaded bore 3 of the positioning cone 2, so that the base body 1 and the positioning cone 2 form a common threaded bore.

[0020] The screw nut according to the invention is driven into a workpiece 5, here two boards to be clamped together. For this purpose, the positioning cone 2 has a striking edge 7 at its free end section 6, which facilitates driving it into the workpiece 5. Depending on the properties of the workpiece 5, the striking edge 7 can also have a cutting edge, which facilitates driving and protects the workpiece 5. To further enhance this effect, the half opening angle α of the positioning cone 2 can alternatively or additionally be between 10° and 25°, preferably 15°. The striking edge 7 defines an opening 8 at the free end section 6, which tapers towards the base body 1 and leads into the threaded bore 3. This opening serves to receive the fastening element 4, with the inside of the end section forming a guide surface 9 for the fastening element 4 through the tapered opening 8, so that it is guided to the internal thread of the threaded bore 3.

[0021] If the fastener 4 is driven into the workpiece 5 such that its bore 10 and the threaded bore 3 are aligned, the fastener 4 can be inserted from the opposite side of the workpiece 5. Upon initial contact with the positioning cone 2, the fastener 4 does not force the nut out of the bore 10, as the forces typically applied do not release the wedge of the positioning cone 2 in the workpiece 5. Therefore, the fastener 4 can be brought into contact with the guide surface 9 and the threaded bore 3 without forcing the nut out of the workpiece 5, and this occurs while the fastener is still inside the workpiece 5.

[0022] If a screw connection is now established by applying a torque to the nut or the fastener 4, the positioning cone 2 is driven further into the workpiece 5 by the tensile force generated along the screw axis 11. To limit the penetration depth of the nut, a stop washer 12 extending transversely to the screw axis 11 can be used, as shown in the first embodiment. Fig. 2 shown, or a washer 13, as shown in the second embodiment in the Fig. 3 It is shown, intended to be.

[0023] The stop washer 12 is part of the nut, i.e., permanently connected to it, and may have a locking pin 14, which is also driven into the workpiece 5. This locking pin 14 provides additional support against a torque applied to the nut.

[0024] As in the second embodiment of the Fig. 3 As shown, a washer 13 is used as a separate component, and a washer receptacle 15 is provided for it, the largest diameter of which, perpendicular to the screw axis 11, is smaller than the largest diameter of the base body 1, perpendicular to the screw axis 11. This allows the base body 1 to form a stop for the washer 13 along the screw axis 11. Preferably, the washer 13 is mounted on the washer receptacle 15 by means of a clamping fit.

[0025] The positioning cone 2 may have longitudinal grooves running along its outer surface for torque support of the screw nut; however, these are omitted for clarity. Fig. 2 and 3 only indicated as dashed lines, parallel to the outer wall of the positioning cone 2.

Claims

1. Screw nut with a base body (1) and a positioning cone (2) connected to the base body (1) and having a threaded bore (3) with an opening (8) leading into the threaded bore (3) and tapering towards the base body (1), wherein the positioning cone (2) has an striking edge (7) at the free end section (6) for driving into a workpiece (5), which striking edge (7) delimits the opening (8), characterised in that a stop disc (12) extending transversely to the screw axis (11) is provided in the transition area between the base body (1) and the positioning cone (2).

2. Screw nut according to claim 1, characterised in that the base body (1) and positioning cone (2) are designed as a single piece.

3. Screw nut according to claim 1 or 2, characterised in that the base body (1) and positioning cone (2) form a common threaded bore.

4. Screw nut according to one of claims 1 to 3, characterised in that the largest diameter of the positioning cone (2) transverse to the screw axis (11) does not exceed the largest diameter of the base body (1) transverse to the screw axis (11).

5. Screw nut according to one of claims 1 to 4, characterised in that the striking edge (7) has a cutting edge for driving into a workpiece (5).

6. Screw nut according to one of claims 1 to 5, characterised in that the half opening angle (α) of the positioning cone (2) is between 10° and 25°.

7. Screw nut according to one of claims 1 to 6, characterised in that longitudinal grooves extending along the outer surface of the positioning cone (2) are provided for torque support of the screw nut.

8. Screw nut according to one of claims 1 to 7, characterised in that the stop disc (12) has at least one locking pin (14) for torque support.

9. Screw nut according to one of claims 1 to 7, characterised in that a washer receptacle (15) is provided in the transition area between the base body (1) and the positioning cone (2), the largest diameter of which washer receptacle (15), transverse to the screw axis (11), is smaller than the largest diameter of the base body (1), transverse to the screw axis (11).