WO2015001018A1

WO2015001018A1 - Method and device for producing a screw element

Info

Publication number: WO2015001018A1
Application number: PCT/EP2014/064177
Authority: WO
Inventors: Berthold Beyfuss; Hans-Jürgen FRIEDRICH; Alfred Radina
Original assignee: Aktiebolaget Skf
Priority date: 2013-07-03
Filing date: 2014-07-03
Publication date: 2015-01-08
Also published as: DE102013212964B4; DE102013212964A1

Abstract

Embodiments of the invention concern a concept for producing a screw element (40; 50) from a workpiece (10), wherein a passage (12) is produced (S1) through the workpiece (10) with a projection (14), it being possible for a thread (32) to be formed in the passage (12), and a thread end section (22) is impressed (S2) into the projection (14) such that the geometry of the thread end section (22) decreases in diameter from an end of the projection (14) remote from the passage (12) in the direction of the thread (32).

Description

Method and Apparatus for Producing a Screw Element Embodiments of the present invention relate to methods and apparatus for making a fastener from a workpiece, and more particularly to methods of making a thread run.

In particular, in a blind assembly of retaining elements (retainers), problems with threading a screw into a (inner) thread of a threaded plate (thread pull) may arise, especially if the retainer pre-assembled, precentered and concealed inside a gear housing and by means of a screw must be "touched" from outside. In this case, simply a beginning of the thread can not be found or screwed.

Another disadvantage is that at the thread outlet in the case of formed (internal) threads of a thread plate, the last thread spirally becomes narrower and thus also more unstable. As a result, after a sliding grinding of the thread plate by means of grinding media, such as stones, this outgoing thread is hammered somewhat back into the previous flank, thereby blocking the thread. Even a previously formed or embossed 45 ° bevel does not prevent this, since in this case, the grinding media (eg stones) can still come into contact with the last thread. In order to remedy this disadvantage, threads are partly countersunk again after the vibratory grinding. Alternatively or additionally, screws can be screwed in and out again in each thread of a threaded plate. It is therefore an object of embodiments of the present invention to improve the prior art with regard to threaded or threaded plates. The object is achieved by a method for producing a screw or fastener with the features of the independent claim. According to a further aspect, a corresponding device for producing the screw or fastener is provided. In a main aspect, embodiments of the present invention provide a method of making a fastener from a workpiece. The method comprises a step of producing a passage through the workpiece with a projection, wherein a thread can be formed in the passage. Further, the method includes a step of embossing a threaded end portion into the projection so that the threaded end portion has a geometry having a diameter decreasing in the direction of thread from a throat remote from the throat. By such a geometry, for example, a chamfer or a centering aid can be formed in the threaded end. According to embodiments, the thread (internal thread) can be formed in the passage or the opening formed thereby in the workpiece after the (threaded) passage and the embossing of the threaded end portion in the protrusion formed by the passage in a further, subsequent step. While in embodiments the forming of the thread in the workpiece or the passage by means of a chipless or machining process, such as milling or cutting, can take place, in contrast, before the passage together with projection, for example, only by means of a chipless forming process, in particular by pulling ( Collar pulling). Collar pulling is a forming process in which, for example, sheet metal or tubes are set up by means of tensile pressure on the collar or overhang called sheet metal passages. Collar or protrusions can be used for many different purposes According to embodiments described herein, they serve as a threaded passage for screwing overall formed centering by a non-cutting process, for example by means of embossing, are produced. Conventionally, centering aids in the form of bevels are often produced by means of machining or cutting processes. According to embodiments, the workpiece to be machined can be, for example, a metal or plastic part, in particular a metal or plastic plate, so that after all the method steps have been carried out, a threaded plate with one or more thread passages can arise as a screw or fastening element.

In embodiments, the passage, together with the projection, can be produced from a first side of the workpiece, for example by means of a first punch. This results in the exit of the first punch from the workpiece on the other, opposite second side of the projection in the form of a bead of material. Normally, threaded passages will be a round bead, ie a round, in particular circular, projection. The threaded end portion formed by the projection can then be formed from the second side of the workpiece in the projection, for example by means of a suitable counter-embossing. A second punch, which is used for this counter-embossing, can thus according to exemplary embodiments specify the geometry, ie also a possible bevel, of the threaded end section. The passage and the threaded end can therefore be formed from different sides of non-cutting into the workpiece, in particular by drawing and (counter) embossing .. According to embodiments, the threaded end or its geometry can be impressed into the projection that its diameter in height a transition from the threaded end to the (inner) thread corresponds to a diameter or core diameter of the thread. On the other hand, at an axial end remote from the (later) thread, the diameter of the threaded end section can be larger. As a result, a centering aid for inserting screws into the thread is advantageously provided by the threaded end section, which according to exemplary embodiments itself has no thread with a profiled notch. It is proposed that the threaded end section is impressed into the projection in such a way that it has at least a first partial region with a surface which essentially has the shape of a lateral surface of a hollow cylinder. By the fact that the surface "substantially has the shape of a lateral surface of a hollow cylinder" is to be understood in particular that at least eighty percent and preferably ninety-five percent of the points of the surface a distance from a straight line, which is parallel to the axial direction of the thread and centered through the thread, which deviates at most twenty percent, preferably at most seven percent and more preferably at most two percent from the average distance of the points of the surface from the straight line.

Furthermore, it is proposed that the threaded end section is embossed into the projection in such a way that the first partial region has at least a part of an inner surface of a hollow cylinder or a part of a lateral surface of a cone with an opening angle which is less than or equal to 30 °, as the inner surface. This allows a precise formation of the thread can be achieved. In particular, it can be reliably prevented that in a vibratory grinding flanks of the thread are damaged at the end.

Advantageously, a maximum extension length of the first portion along the axial direction of the thread between 0.5 mm and 3 mm. This allows a simple and precise design can be achieved.

The threaded end section is preferably embossed into the projection in such a way that the threaded end section has a second partial region which has at least part of a lateral surface of a cone as inner surface region. In this way, a simple manufacture of a screw connection can be achieved.

It is also proposed that the threaded end section is impressed into the projection in such a way that at least a part of the second section is arranged between the first section and the thread. Thereby, a guide surface for guiding a screw in the manufacture of a screw connection can be achieved. Advantageously, the first portion forms an end portion of the screw member with respect to the axial direction of the thread. As a result, a positioning of a screw in the manufacture of a screw connection can be achieved in a simple manner. In another aspect, embodiments of the present invention also provide a corresponding apparatus for making a fastener from a workpiece. The device comprises a device for producing a passage through the workpiece with a projection, wherein in the passage a thread can be formed. Furthermore, the device comprises a device for impressing a threaded end section into the projection, such that the threaded end section has a geometry which has a diameter decreasing in the direction of thread from an end of the projection facing away from the passage. Both in the device for producing the passage and in the device for impressing the threaded end portion may be corresponding stamp. In particular, the stamp for impressing the threaded end portion has for this purpose to the threaded Endabschnittsgeometrie inverse or negative geometry.

According to another aspect, embodiments of the present invention also provide a fastener, in particular a threaded element, such as a threaded plate, having at least one (internal) thread and a threaded end portion disposed at one end of a thread, the threaded end portion a Geometry having one of a thread facing away from the end of the projection in the direction of thread decreasing diameter. With embodiments, a screw can be provided, which allows easy attachment. In particular, a simple production of a screw connection with the screw element can be achieved, in particular in a situation in which the screw element can not be seen. In particular, it can be achieved that in the case in which the screw element has been machined by vibratory grinding, due to the geometrical shape of the threaded end portion, contact of grinding media used in the vibratory grinding and which may be formed in particular by stones, with the end of the thread is omitted, so that flanks of the thread, which are arranged at the end of the grinding media are undamaged. Further advantages emerge from the following description of the drawing. In the drawings, an embodiment of the invention is shown. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

1 shows a method for producing a screw element from a workpiece, according to an embodiment;

Fig. 2a shows a section through and a plan view of an element which arises in the manufacture of the screw as an intermediate step, and

Fig. 2b shows a section through and a plan view of a screw according to an embodiment; and

FIG. 3 shows a perspective view of the screw element according to FIG. 2. FIG.

Various embodiments will now be described in more detail with reference to the accompanying drawings, in which some embodiments are illustrated. In the figures, the thickness dimensions of lines, layers and / or regions may be exaggerated for the sake of clarity.

In the following description of the attached figures, which show only some exemplary embodiments, like reference characters may designate the same or similar components. Further, summary reference numerals may be used for components and objects that occur multiple times in one embodiment or in a drawing but are described together in terms of one or more features. Components or objects which are described by the same or by the same reference numerals may be the same, but possibly also different, in terms of individual, several or all features, for example their dimensions, unless otherwise explicitly or implicitly stated in the description. Although embodiments may be modified and changed in various ways, exemplary embodiments are illustrated in the figures as examples and will be described in detail herein. It should be understood, however, that it is not intended to limit embodiments to the particular forms disclosed, but that embodiments are intended to cover all functional and / or structural modifications, equivalents and alternatives that are within the scope of the invention. Like reference numerals designate like or similar elements throughout the description of the figures. Note that an element referred to as being "connected" or "coupled" to another element may be directly connected or coupled to the other element, or intervening elements may be present. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other terms used to describe the relationship between elements should be interpreted in a similar fashion (eg, "between" versus "directly in between,""adjacent" versus "directly adjacent," etc.).

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the embodiments. As used herein, the singular forms "a,""a,""an," and "the" are also meant to include the plural forms unless the context clearly indicates otherwise. Further, it should be understood that the terms such as "including,""including,""having and / or having," as used herein, include the presence of noted features, integers, steps, operations, elements, and / or components but does not preclude the presence or addition of one or more features, integers, steps, operations, elements, components, and / or groups thereof. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly assigned to one of ordinary skill in the art to which the embodiments pertain. It should also be made clear that expressions such as those defined in commonly used dictionaries should be interpreted as having meaning that is consistent with its meaning in the context of the relevant art, and is not to be interpreted in an idealized or overly formal sense, unless expressly defined herein. Fig. 1 illustrates a method for producing a screw or fastener from a workpiece 10, which may be, for example, a sheet.

The method comprises a step Sl, in which a passage 12 is produced by the workpiece 10 with a projection 14, for example by means of pulling, in particular collar pulling. In a later method step, which is not shown in FIG. 1, a further thread can be formed in the passage 12 (see FIG. 2 b). In order to produce the (threaded) passage 12, the workpiece or the sheet metal part 10 can be positioned on a die 16. By a controlled downward movement of an upper tool or punch 18 then takes place a material or sheet metal forming. Due to the translational movement of the punch 18, whose diameter d _{18 is} less than a diameter d ₂ o a co-operating with the punch 18 opening 20 in the die 16, the collars pull on the cut-out opening or the passage 12 annular edges or collar 14 formed. The diameter d _{18 of} the punch 18 and thus also the diameter of the resulting passage 12 substantially correspond to one for producing the core diameter of the later to be drawn into the passage 12 internal thread suitable diameter.

The method further comprises a further step S2, in which a threaded portion 22 is impressed into the projection 14 of the workpiece 10, such that the threaded end portion 22 has a geometry which is one end of the projection 14 remote from the passage or opening 12 in the direction of passage 12 has decreasing diameter or radius. In step S2, the threaded end portion 22 can be formed or pressed into the projection 14 by means of an embossing punch 26 guided in a bush 24. For this purpose, the sheet metal part 10 can be fixed with a counter-pressure plate 28. According to some embodiments, the embossing punch 26 may have an embossing region 30 at its end facing the passage, which comprises a first subregion 30-1 and a second subregion 30-2, which predetermine the geometry of the embossed threaded end section 22. According to embodiments, a Diameter of the first portion 30-1 of the die 26 have a larger diameter than a diameter of the second portion 30-2. This, in turn, causes the threaded end portion 22 to have a geometry that is a decreasing diameter from the axial end of the projection 14 (the axial direction is defined by a passage symmetry axis 30) in the direction of the passage 12, whereby the threaded end portion 22 advantageously provides a centering aid for insertion of screws in the passage 12 can form. According to embodiments, the threaded end portion 22, which can serve as Schutzzentrierung, even no thread on. After the operation by-neck (step S l) can in the subsequent operation (step S2), the sheet metal part 10 are pressed in a corresponding device so by means of the counter-holder 28 against a die 26, which is inserted in a socket 24. Here, the die 26 displaces the material on the side, proportionately upwards and in the cylindrical wall portion. The cylindrical, foremost part 30-1 of the punch 26 corresponds almost to the core hole of the thread, which prevents a material throw reduces the core hole diameter at the thread inlet.

As is clear from the illustration of the two method steps S1 and S2 in FIG. 1, in embodiments the passage 12 (by means of method step S1) and the threaded end section 22 (by method step S2) can be formed into the workpiece 10 from different sides. Both method steps Sl and S2 are according to embodiments each non-cutting process steps. The method step S1 is, for example, a pulling, in particular a collar pull. The method step S2 is, for example, embossing.

After a (forming) method for producing a screw element from the workpiece 10 has been explained above, the screw element 50 itself or a precursor 40 will be explained in the following with reference to FIGS. 2 and 3. 2a shows a section on the left through an element 40, which is produced during a production of a screw element after a drawing and / or embossing, ie after carrying out the method steps S1 and S2, and into which a thread can still be inserted for completion. The Fig. 2a right shows the same element 40 in plan view. FIG. 2 b on the left shows a section through a completely manufactured screw or fastening device. transmission element 50, which is designed as a threaded passage element. The screw 50 may be integrally formed of metal and having a thread formed as an internal thread 32, which can be formed in a further process step after the two steps Sl and S2 in the thread passage 12. Both cutting and non-cutting methods are available for this purpose. The Fig. 2b right shows the same fastener 50 in plan view. FIG. 3 shows a perspective view of the complete fastening element or threaded element 50 according to one exemplary embodiment. A portion of the threaded end portion 22 of the member 40 or 50 embossed in the collar 14 immediately adjoins an area for the thread 32 so that the threaded end portion 22 is located at one (axial) end of the threaded portion. That is, one end of the thread forms a transition region of thread 32 to the unthreaded threaded end portion 22. The threaded end portion 22 may be embossed into the projection 14 such that the threaded end portion 22 has a first portion 34 having a surface 36 which is in the shape of an inner surface of a hollow cylinder may have. As already explained, the first partial region 34 can be produced by drawing and / or embossing with the method steps S 1 and S2. Further, the first portion 34 may be formed without thread and extend axially along a length X. In other words, the hollow cylinder of diameter D forming the first portion 34 may have a depth X (in the axial direction).

The threaded end portion 22 may be embossed into the projection 14 such that the first portion 34 forms an end portion of the screw 40, 50 with respect to the axial direction 46 of the thread and is part of the projection 14 of the screw member 40, 50. Further, the first portion 34 may have an extension length X along the direction 46, which may be between 0.5 mm and 3 mm. For example, a diameter D of the first portion 14 may be slightly larger than an outside diameter of an M8 thread. The thread 32 may be formed for example as M8 thread.

The threaded end portion 22 may be embossed into the projection 14 such that the threaded end portion 22 may further include a second portion 38 which may include a portion of the thread 32. In addition, the second portion 38 may have an inner surface portion 44, which has the shape of a portion of a lateral surface of a Tapered to form a chamfer. A portion of the second portion 34 having the inner surface portion 44 is disposed between the first portion 34 and the thread 32. That is, the chamfer formed by the second portion 38 is located between the first portion 34 and the thread, so that by the chamfer of the (inner) diameter of the threaded end portion is matched to a diameter of the thread 32.

When producing the screw element 40, 50, the first portion 34 and a further portion 38 can be produced by embossing and / or drawing (see FIG. 1). The part 38 forms after introduction of the thread 32, the second portion. Furthermore, the part 38 may have the shape of a part of a lateral surface of a cone with an opening angle of about 90 °, i. a chamfer. Thus, an angle T of the part 38 relative to a perpendicular to the direction 46 may be about 30 ° <T <60 °, in particular 45 °. Thus, the threaded end portion 22 may be embossed into the projection 14 such that its diameter at the level of a transition from the second portion 38 of the threaded end portion 22 to the thread 32 substantially corresponds to a (core) diameter of the thread 32. In an exemplary M8 internal thread this would be about 6.65 mm. According to the invention, a gear can have the screw element 40 or 50. In this case, the screw 40, 50 may be arranged in a housing of the transmission. In an assembly, a portion of a male-threaded screw may be inserted through a hole in the housing, with a fitter unscrewing the screw into the screw without seeing the screw member. The screwing is simplified by the inventive design of the screw. The screw can be part of a component that serves for the axial preload of a bearing.

According to exemplary embodiments, therefore, a device is provided with which a centering embossing can be produced. For this purpose, the following advantages can be brought about on the sheet metal part: the screw is pre-centered to a certain extent by the diameter "D" and the finding of the position is facilitated by the slope "T". It is steered into the right position, reduces an inclination and can thus be easily screwed. The cylindrical counterbore is made in the depth "X" so long that grinding media (Gleitschleifsteine) can no longer come into contact with the first thread and thus a hammering the gear is prevented.

The features disclosed in the foregoing description, the appended claims and the appended figures may be taken to be and effect both individually and in any combination for the realization of an embodiment in its various forms.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to others of ordinary skill in the art. Therefore, it is intended that the invention be limited only by the scope of the appended claims and not by the specific details presented in the description and explanation of the embodiments herein.

LIST OF REFERENCE NUMBERS

X extension length

T angle

D diameter

10 workpiece

12 draft

14 cantilever

16 matrix

18 stamps

20 opening

22 threaded end section

24 socket

26 stamped

28 counter pressure plate

30 pulling axle

32 threads

34 first subarea

36 inner surface

38 second subarea

40 screw element

44 inner surface

50 screw element

Claims

P a n t a n s p r e c h e

Method for producing a screw element

Method for producing a screw element (40, 50) from a workpiece (10), comprising the following steps:

Producing (Sl) a passage (12) through the workpiece (10) with a projection (14), wherein in the passage (12) has a thread (32) can be formed;

Embossing (S2) a threaded end portion (22) in the projection (14), so that the threaded end portion (22) has a geometry that one of the passage (12) facing away from the end of the projection (14) in the direction of thread (32) decrease Diameter.

The method of claim 1, wherein the passage (12) and the threaded end portion (22) are formed from different sides into the workpiece (10).

The method of claim 1 or 2, wherein after the production (Sl) of the passage (12) and the embossing (S2) of the threaded end portion (22), the thread (32) is formed in the passage (12).

Method according to one of the preceding claims, wherein the threaded end portion (22) is embossed into the projection (14) such that its diameter at the level of a transition from the threaded end portion (22) to the thread (32) corresponds to a diameter of the thread (32) ,

Method according to one of the preceding claims, wherein the threaded end portion (22) is embossed in the projection (14), so that the threaded end portion (22) at least a first portion (34) having a surface (36). has, which has substantially the shape of a lateral surface of a hollow cylinder.

6. The method of claim 5, wherein the threaded end portion (22) is embossed in the projection (14), so that the first portion (34) at least part of an inner surface of a hollow cylinder or a part of a lateral surface of a cone with a Öffhungswinkel, the is less than or equal to 30 °, as inner surface (36).

7. The method according to any one of claims 5 or 6, wherein the threaded end portion (22) is embossed into the projection (14), so that the threaded end portion (22) has a second portion (38) which at least part of a lateral surface of a cone having an inner surface area.

8. The method of claim 7, wherein the threaded end portion (22) is embossed in the projection, so that at least a part of the second portion (38) between the first portion (34) and the thread (32) is arranged.

A method according to any one of the preceding claims, wherein the threaded end portion (22) is embossed into the projection (14) such that the first portion (34) defines an end portion of the screw member (40; 50) with respect to the axial direction (46) of the thread (32) forms.

Device for producing a screw element (40; 50) from a workpiece (10), having the following features:

a device for producing (Sl) a passage (12) through the workpiece (10) with a projection (14), wherein in the passage (12) has a thread (32) can be formed;

a device for embossing (S2) a threaded end section (22) in the projection (14), which is formed such that the threaded end section (22) has a geometry which is one end of the projection (14) remote from the passage (12). in the direction of thread (32) has decreasing diameter.