DE102022130707A1 - SCREW WITH ELECTRICALLY CONDUCTIVE ADDITIONAL MATERIAL - Google Patents

Abstract

A screw is provided, wherein the screw has an external thread for connecting the screw to an internal thread of a component corresponding to the external thread, a blind hole extending from a screw head of the screw along a longitudinal direction of the screw, a through hole extending obliquely to the longitudinal direction of the screw, which connects the blind hole to the external thread, and an electrically conductive additional material arranged in the blind hole.

Description

The present invention relates to a screw, a motor vehicle with the screw and a method for connecting the screw to a component.

A screw can be understood as a component for a positive connection. More precisely, the screw has a screw head for a positive connection with a tool that allows the screw to be screwed in or turned in and optionally unscrewed or turned out again. The screw also has a (screw) shaft. This can be a cylindrical and/or at least partially slightly tapered or conical body, in the surface of which a thread, the so-called external thread, is introduced, e.g. cut or rolled. This external thread is used for the positive connection of the screw with a counter thread or internal thread of a component. A distinction is made between two types of screws: self-tapping screws, which have a slightly conical shaft and in which the counter thread is cut when screwed into the workpiece or component (e.g. made of wood, plastic, metal or stone), and screws with standard threads (i.e. screws in which the external thread is designed as a standard thread), in which the counter thread is cut into the workpiece, usually metal or plastic, before screwing.

The EP 3 225 555 A1 relates to a fastener comprising an elongated shaft having a first end, a second end and a shaft body, a head portion, and a threaded portion. At least one internal feed channel extends through the head portion and the shaft body and terminates proximate the threaded portion. The fastener has a plurality of grooves formed along an outer surface of the shaft body and an outer surface of the head portion and spaced circumferentially. Each groove has a first end and extends from a first location proximal to the threaded portion along the outer surface of the shaft body and radially outward along the outer surface of the head portion. The fastener further has one or more lateral feed channels extending laterally through the shaft body and connecting the internal feed channel to at least two opposing grooves on the outer surface of the shaft body.

With conventional screws, a preload force acting in a longitudinal direction of the screw when the screw is screwed in causes the external thread of the screw or the screw thread to expand along the longitudinal direction and the counter thread or internal thread in the component to shorten or compress along the longitudinal direction. As a result, the pressure between the tooth flanks of the two threads decreases as the distance from the screw head increases, until there is no longer any support or contact between the tooth flanks of the two threads. With a screw that is used to transmit electrical energy between the component into which the screw is screwed and the screw, no electrical energy can be transmitted in the area where the tooth flanks no longer contact each other.

Against the background of this prior art, the object of the present disclosure is to provide a device and a method which are each suitable for enriching the prior art.

A specific embodiment of the disclosure can solve the problem of optimizing a screw connection with regard to a transmission of electrical energy from a component into which the screw is screwed to the screw or vice versa.

The problem is solved by the features of the independent claim. The subordinate claims and the dependent claims each contain optional further developments of the disclosure.

The task is then solved by a screw. The screw has an external thread, optionally a standard thread, for connecting the screw to an internal thread or counter thread of a component that corresponds to the external thread, a blind hole that extends from a screw head of the screw along a longitudinal direction of the screw and a through hole that extends diagonally, optionally perpendicularly, to the longitudinal direction of the screw and connects the blind hole to the external thread. An electrically conductive additional material is arranged in the blind hole.

In other words, the screw has two holes. One of the two holes is open at the top, i.e. it extends from the screw head into the interior of the screw. Since this hole is a blind hole, it does not completely penetrate the screw, but rather ends in the screw. The second or other of the two holes is a through hole, i.e. this hole has two openings. A first of the two openings is located on the external thread and a second is arranged on the blind hole. The through hole can extend radially, ie diagonally to the longitudinal direction, through the entire screw, but it is also possible that the through hole ends in the blind hole and thus does not extend radially through the entire screw. The through hole can also be referred to as a (connecting) channel, which connects the blind hole with the external thread of the screw.

For the definition of the screw, reference is made to the introductory or above part of the description, i.e. the screw can be a generic screw as described at the beginning.

The screw can, for example, be a shaft screw, i.e. a screw with a partial thread or a screw in which only part of the shaft is provided with an (external) thread.

The screw head can, for example, be designed as an external square or an external hexagon.

The screw described above offers a number of advantages. Among other things, the screw enables improved transmission of electrical energy from a component into which the screw is screwed to the screw or vice versa. This is achieved by the fact that the electrically conductive filler material, which is initially arranged in the blind hole in an initial state, can be pressed or pressed out of the blind hole through the through hole into the area of the external thread of the screw and thus between the external thread of the screw and the internal thread of the component when the screw is screwed in. Since the filler material is electrically conductive, the filler material can not only create contact between the tooth flanks of the two threads that are not in direct contact with each other due to elongation or compression, but electrical energy can also be transmitted via the filler material in those areas of the external thread of the screw in which the tooth flanks are not in direct contact with each other.

In the following, optional further developments of the screw described above are explained in detail, whereby these optional further developments, alone and/or in combination with one another, reinforce the disclosed advantages described above.

The filler material may contain or consist of tin. Additionally or alternatively, the filler material may contain or consist of contact grease. The term “comprising” is not to be understood as exhaustive in this case, i.e. if a component contains substance X, this component can also contain substance Y and/or substance Z in addition to substance X. The term “consist” is to be understood as exhaustive in this case, i.e. if a component contains substance X, this component cannot contain any other substance in addition to substance X. Furthermore, the term “a” or “an” is not to be interpreted as exhaustive in this case, but should rather be understood as if the component contained “at least one” or “at least one” component X.

The blind hole can have an internal thread for another screw. In other words, another screw can be screwed into the screw, or more precisely into the blind hole of the screw, which pushes the additional material out of the blind hole in the manner described above as the screw is screwed in.

The filler material can have such a nature that the filler material is or can be pressed out of the blind hole through the through hole into an area between the external thread of the screw and the internal thread of the component by screwing the additional screw into the blind hole of the screw, so that the external thread and the internal thread are electrically conductively connected to one another via the filler material.

The additional material can have the said properties at room temperature, i.e. at an ambient temperature greater than 15°C, optionally greater than 20°C or 25°C. Such temperatures are common in production or assembly halls for motor vehicles and therefore enable the screw to be used in motor vehicle production without additional effort.

The filler material can be in a solid state at room temperature. This offers the advantage, inter alia, that the filler material does not flow out of the screw before the screw is tightened.

The through hole can run perpendicular to the longitudinal direction of the screw. From a manufacturing point of view, this is a design that can be implemented with relatively little effort.

Furthermore, the disclosure relates to a motor vehicle having a screw as described above.

The motor vehicle may be a passenger car, optionally an automobile, a motorcycle and/or a commercial vehicle, such as a truck.

What is described above with reference to the screw also applies analogously to the motor vehicle and vice versa.

Furthermore, the disclosure relates to a method for connecting a screw to a component, wherein the screw has an external thread, a blind hole extending from a screw head of the screw along a longitudinal direction of the screw, a through hole extending obliquely to the longitudinal direction of the screw, which connects the blind hole to the external thread, and an electrically conductive additional material arranged in the blind hole.

The method comprises screwing the screw into the component so that the external thread of the screw engages with an internal thread of the component corresponding to the external thread, and pressing the additional material out of the blind hole through the through hole into an area between the external thread of the screw and the internal thread of the component so that the external thread and the internal thread are electrically conductively connected to one another via the additional material.

What is described above with reference to the screw and the motor vehicle also applies analogously to the process and vice versa.

• 1 zeigt schematisch eine offenbarungsgemäße Schraube in einem eingeschraubten Zustand zu Erklärungszwecken, und
• 2 zeigt schematisch ein Ablaufdiagramm eines Verfahrens zum Verbinden der Schraube mit einem Bauteil.

Below is an embodiment with reference to 1 and 2 described.

• 1 shows schematically a screw according to the disclosure in a screwed-in state for explanatory purposes, and
• 2 shows a schematic flow diagram of a method for connecting the screw to a component.

In 1 the screw 1 according to the disclosure, which is rotationally symmetrical along its longitudinal axis 2, is shown in a cross-section.

The screw 1 comprises an external thread 3 for connecting the screw 1 with an internal thread 5 of a component 4 corresponding to the external thread 3.

The screw 1 further comprises a blind hole 7 extending from a screw head 6 of the screw 1 along the longitudinal direction 2 of the screw 1, which has an internal thread 11 for a further screw 10, and a through hole 8 extending perpendicular to the longitudinal direction 2 of the screw 1, i.e. radially, which connects the blind hole 7 to the external thread 3.

In an initial state of the screw 1, an electrically conductive additional material 9, such as a tin rod and/or contact grease, is arranged in the blind hole 7.

In a first step S1 of the method, the screw 1 described above is screwed into the component 4 so that the external thread 3 of the screw 1 engages with the internal thread 5 of the component 4 corresponding to the external thread 3.

In a second step S2 of the method, the additional material 9 is pressed out of the blind hole 7 through the through hole 8 into an area 12 between the external thread 3 of the screw 1 and the internal thread 5 of the component 4 by screwing the further screw 10 into the blind hole 7, so that the external thread 3 and the internal thread 5 are electrically conductively connected to one another via the additional material 9 in this area 12.

For this purpose, the additional material 9 has such a nature that the additional material 9 can flow at room temperature from the blind hole 7 through the through hole 8 into the area 12 by screwing the further screw 10 into the blind hole 7 of the screw 1.

This can specifically mean that tin with a tensile strength of Rm = 35 MPa is used as the additional material 9, as already indicated above. When using an M3 screw 8.8 as the additional screw 10, the preload force Fv = 2.3 kN at a standard tightening torque of 1.3 Nm according to DIN 912. The tin flows when the yield stress Sigma is reached, i.e. approximately Rm < Sigma with Sigma = F/A = 2300N/((0.5*3mm) ² *pi) = 325MPa. The tin therefore flows plastically between the larger screw 1 and the component 4, which is designed as a nut, for example, by tightening the screw 10, as shown by the arrows in 1 indicated.

• Es kann eine hohe elektrische Leitfähigkeit durch Einpressen des leitfähigen Mediums 9 zwischen die Schraube 1 und das Bauteil 4 erreicht werden.

In summary, the screw 1 according to the embodiment allows the following advantages to be achieved:

• A high electrical conductivity can be achieved by pressing the conductive medium 9 between the screw 1 and the component 4.

A targeted use of a contact surface on the thread flanks for electrical contact for a defined current flow from a Contact point at the screw head 6 on the screw thread 3 to the joining partner 4 becomes possible.

This makes it possible to support or replace the current flow at the direct contact points between the clamping part 13 and the component 4, which results in a simpler surface design of the joining partners with regard to roughness, flatness, oxide layer, etc.

Furthermore, the solution can prevent any impairment of technical cleanliness in series assembly plants, since there is essentially no risk of carryover of the medium 9, since the screw 1 can be closed and delivered to the assembly line filled with the medium 9.

Furthermore, there is essentially no change in the properties of the screw connection, since the introduction of the medium 9 on the thread flanks only takes place after screwing, i.e. essentially neither friction values nor setting behavior change.

In particular, the use of contact grease as medium 9 offers the advantage that corrosion protection of the cable path can be achieved in the event of the penetration of aqueous solutions.

List of reference symbols

1

screw

2

Longitudinal direction

3

External thread or screw thread

4

Component, optional nut

5

Internal thread or counter thread

6

Screw head

7

blind hole

8th

Through hole

9

electrically conductive filler material or electrically conductive medium

10

additional screw

11

Internal thread in blind hole

12

Area into which the electrically conductive medium is pressed

13

Clamping part between screw head and component or joining partner

S1 - S2

Process steps

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. 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

• EP 3225555 A1 [0003]

Claims (10)

Screw (1), the screw (1) having: - an external thread (3) for connecting the screw (1) to an internal thread (5) of a component (4) corresponding to the external thread (3), - a blind hole (8) extending from a screw head (6) of the screw (1) along a longitudinal direction (2) of the screw (1), and - a through hole (7) extending obliquely to the longitudinal direction (2) of the screw (1), which connects the blind hole (8) to the external thread (3), characterized in that - an electrically conductive additional material (9) is arranged in the blind hole (7). Screw (1) after Claim 1 , characterized in that the additional material (9) comprises or consists of tin. Screw (1) after Claim 1 or 2 , characterized in that the additional material (9) comprises or consists of contact grease. Screw (1) according to one of the Claims 1 until 3 , characterized in that the blind hole (7) has an internal thread (11) for a further screw (10). Screw (1) after Claim 4 , characterized in that the additional material (9) has such a nature that the additional material is pressed by screwing the further screw (10) into the blind hole (7) of the screw (1) from the blind hole (7) through the through hole (8) into an area (12) between the external thread (3) of the screw (1) and the internal thread (5) of the component (4), so that the external thread (3) and the internal thread (3) are electrically conductively connected to one another via the additional material (9). Screw (1) after Claim 5 , characterized in that the additional material (9) has said properties at room temperature. Screw (1) according to one of the Claims 1 until 6 , characterized in that the additional material (9) has a solid state of aggregation at room temperature. Screw (1) according to one of the Claims 1 until 7 , characterized in that the through hole (8) runs perpendicular to the longitudinal direction of the screw (1). Motor vehicle, characterized in that the motor vehicle has a screw (1) according to one of the Claims 1 until 8th having. Method for connecting a screw (1) to a component (4), the screw (1) having: - an external thread (3), - a blind hole (7) extending from a screw head (6) of the screw (1) along a longitudinal direction (2) of the screw (1), - a through hole (8) extending obliquely to the longitudinal direction (2) of the screw (1), which connects the blind hole (7) to the external thread (3), and - an electrically conductive additional material (9) arranged in the blind hole (7), characterized in that the method comprises: - screwing (S1) the screw (1) into the component (4) so that the external thread (3) of the screw (1) engages with an internal thread (5) of the component (4) corresponding to the external thread (3), and - pressing out (S2) the additional material (9) from the blind hole (7) through the through hole (8) into an area (12) between the external thread (3) of the screw (1) and the Internal thread (5) of the component (4) so that the external thread (3) and the internal thread (5) are electrically connected to one another via the additional material (9).

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