WO2013113312A1 - Method and device for producing metal components with a shank that is deformed along the longitudinal axis thereof into at least one helix - Google Patents

Description

 Method and device for producing metallic components with a shank which is deformed along at least one helix along its longitudinal axis

The invention relates to a method for the production of metallic components with a shaft which is deformed along its longitudinal axis to at least one helix and a device suitable for carrying out the method.

 From the fastening and connection technology components made of metal are known, which consist of a shaft and head portion, wherein the shaft portion is usually formed as a cylindrical pin or pin, which is provided on its lateral surface with a thread. These are screws, threaded bolts, dowels or anchors as fastening or connecting means.

 Also known are rotatable screws made of metal, which are used as transport screws, dosing and screw conveyors, and mixing screws or worm gears. These components also have a shaft and a head section. On the lateral surface of the shaft helical or spirally extending elements are arranged. Gear worms are groove-shaped threaded structures in the form of a spiral for power transmission. The head section of these screws is used for clamping in a chuck which is connected to a rotary drive.

WO 2010/142458 A2 discloses a method for producing elongated metal components with helical grooves, in particular spiral drills or screws. A blank is introduced without prior heating in a guide die and subsequently cold formed in a jaw tool with at least two movable jaws whose inner wall has at least one section with a contour designed as a negative to form helical grooves. The cold forming process is triggered by an axially movable plunger which engages the free end of the blank located in the guide die. Due to the applied pressing force of the blank is pressed without prior heating at least partially through the central opening of the closed jaw tool. In this case, helical grooves are produced on the lateral surface of the blank during the contact with the tool contour by plastic cold deformation. After completion of the cold pressing process, the baking tool is opened and the formed into a drill or a worm blank removed from this.

In addition, further, upstream cold forming stages can be provided in which the shank and / or head of the blank are preformed. From EP 2 156 909 B1 a method for the production of fastening or connecting means with radial outer contours, in particular screws or threaded bolts, of solid metal material is known.

 A prefabricated blank is inserted into a multi-part jaw tool with the jaws open in the initial state, so that at least at the points where the jaws are open, located in the axial direction extending recesses. The individual jaws of the pressing tool have on their inner side for forming the radial outer contour a corresponding inner profiling as a negative. By closing the jaws by means of radial force, a thread is pressed onto the shaft-shaped section of the finished blank. By formed in the shank-shaped portion of the blank recesses prevents material from getting into the jaws of the baking tool during the pressing process. In the region of the recesses extending in the axial direction, no radial outer contour is produced during the pressing process.

 Only in screws deviating from the aforementioned classical design execution (DE 31 16 101 C2) is known. In this screw, the shaft to a spiral or helix, also called helix, deformed. The trained as a helical shaft forms the screw thread.

 Such a screw is used for connecting semi-rigid materials. The preparation of this screw is done by winding a cut wire section. In this screw, the helical pitch at the head end is smaller than at the tip side area. The production by winding wire is, especially when more stable screw elements are required, associated with a high cost. In addition, so only screw with a single helix can be produced.

 The invention has for its object to provide a method for the production of components from metallic materials, which is suitable for economical mass production of components with more stable helices and with slight technological changes, the production of different embodiments, especially those with multiple helices or helices , allows. Furthermore, a device suitable for carrying out the method is to be provided.

According to the invention the object is achieved by the features specified in claim 1. Advantageous embodiments and further developments form the subject matter of claims 2 to 14. A device suitable for carrying out the method is subject matter of claim 15. Claims 16 to 25 relate to advantageous embodiments of features of the device. To produce the helical components, a rod-shaped blank made of solid material or a sleeve designed as an elongate component is used. The blank may also consist of a sleeve which has at one end a section made of solid material.

 The blank may be prefabricated, e.g. as part of a complex production in a multi-stage press. According to a preferred embodiment, a preformed blank may be used which consists of a shaft-shaped section with one or more longitudinally extending, eccentrically arranged strands. Both a rod made of solid material or the like and a sleeve can be preformed into a blank with one strand or two strands or so-called "legs" or "legs".

 In the subsequent extrusion process, a single rod-shaped strand or a plurality of strands arranged parallel to one another is / are converted into a helix or a plurality of helices twisted into one another.

 The prefabricated or preformed blank is inserted or inserted into a guide and subsequently formed by extrusion in at least one multi-part jaw tool with at least two movable jaws whose inner wall is provided with a helical contour designed as a negative.

The guide may be a guide die or the jaws of the jaw tool may have a corresponding guide.

It is essential that the center of gravity of the outlet opening of the jaw tool relative to the center line of the tool or the component is displaced in an offset direction. The guide for the blank is part of the tool. The centroid of the outlet opening of the baking tool is therefore not in the center line of the component or the blank receiving guide.

The forming force required for extrusion is generated by means of a force acting on the free end of the blank press ram.

 As a result of the pressing pressure exerted on the blank, it is pressed at least partially through the eccentrically arranged opening of the closed jaw tool. During the contact with the tool inner contour, a plastic deformation takes place with the formation of a helical strand.

The shank of the blank is at least formed into a stable strand with a nearly constant cross-section as a helix. This is only made possible by the offset between the centroid of the outlet opening of the jaw tool relative to the outgoing from the centroid of the central opening of the guide normals. After completion of the pressing process, the jaw tool is opened and the component produced with one or more helix transformed strand / strands taken from this.

 Helices in the aforementioned sense are curves with a constant, increasing, or decreasing radius.

 A preferred variant of the method consists in that, in an extrusion process, two or more strands can be formed synchronously at a distance from one another as helices, the individual strands being wound around each other without contact, in the manner of a two-start screw.

 A variant of the invention may also be that in the middle of the blank, along the longitudinal central axis, a first straight strand is pressed and the second strand, whose longitudinal central axis is offset to the longitudinal central axis of the first strand, is pressed as a single helix, which during the pressing process winds around the first strand. The first straight strand may have a tip at its end, the z. B. is used as a centering in the case of a screw.

The straight strand can also already be produced as part of a prefabrication of the blank.

 A component according to the invention can also consist of at least two mutually parallel, longitudinally extending stable strand-like arms with a constant or in the pressing direction decreasing cross section each in the form of a helix. The original shaft of the blank is formed into at least two helical strands starting at the head section. The strands are arranged relative to one another in such a way that their areas of center of gravity are at a distance from the longitudinal center line of the head section by a certain amount, that is to say an offset. The amount of offset is usually in the millimeter range.

 Such fastening or connecting means allow a variety of different design and applications in industry and construction. To extrude two or more strands as helices, a stable mandrel can be centrally inserted and fixed in the opening of the jaw tool. The helical strands formed during the pressing process wind around the mandrel or surround it. After completion of the pressing operation, the mandrel is removed again and the jaw removal tool is opened. The mandrel can protrude into the opening of the baking tool or even protrude from the tool.

When using a sleeve as a blank, the mandrel is pushed to the upper end of the sleeve or even protruding. The lower portion of the ram is also formed as a sleeve, which during the pressing process on the mandrel pushes. The manufactured component is longer than the blank used after the pressing process. There is a change in length. By the pressing process, a material hardening of the helix strands occurs simultaneously.

 All process steps, starting from a cut rod or wire section, can be carried out in a multi-stage press.

 If necessary, the blank can be heated before the extrusion process. The blanks may be made of different metallic materials, e.g. Aluminum, copper, steel or alloys that can be formed by extrusion. The helical strands produced by the extrusion process may have different cross-sectional shapes, e.g. round, oval, elliptical, polygonal (square, hexagon). The opening of the baking tool is adapted to the corresponding cross-sectional shape. The opening of the jaws can also have a cross-sectional shape which changes in the pressing direction and which is round, for example, at the point of entry into the jaw tool and elliptical or oval at the exit point.

 Depending on the desired design of the helix / helices of the component, the shape-forming contour of the jaws, possibly in conjunction with the mandrel, may be different, in particular with regard to arc length, curvature and torsion or pitch of the helix.

In embodiments with two or more strands in the form of a helix, the individual helices or strands can be spaced apart from one another in different parallel directions, or it is also possible to form two or more helices which are intertwined and which do not touch one another. Also possible is a design with a straight strand and a helix that is wound around this strand.

 The inner contour of the jaw tools, for example, is designed so that the adjacent helices are offset depending on the number of helices in the pitch. In a two-helix version, these are offset by half a turn or pitch.

 For the production of components according to the invention with a plurality of helix strands, a multi-part jaw tool can be used, which has eccentrically arranged press openings, which are delimited by the peripheral jaws and a central core or insert. It can also be small single jaw tools are used, with a jaw tool is provided for each helix strand.

For components having two or more strands in the form of a helix, the outer boundary of the helices may be greater than or less than or equal to the outer diameter of the blank or the outer periphery of the head portion.

In particular, screws, threaded bolts and anchoring elements, such as concrete anchor dowels or the like, can be produced by the process according to the invention. When screwed into holes or holes, the helical strands are slightly compressed.

 Also rotatable screws can be produced according to this procedure, which are used in mixing, conveying and metering units or are used as gear worms for power transmission.

 The components produced according to the invention, such as fastening or connecting means or screws, can subsequently be replaced by further forming operations, e.g. for the formation of the head section, to be treated. If necessary, the strand (s) formed into a helix can also be subsequently transformed.

By subsequent upsetting the pitch of the helix can be reduced, and inevitably the length of the strand is lower.

 The invention will be explained below with reference to some examples. In the accompanying drawing show:

 Fig. 1 three different embodiments of the invention produced components in perspective view

 Fig. 2 different variants of blanks in a simplified representation as a longitudinal section;

 3 shows the individual method steps A, B and C for producing a screw with a helical strand, in a simplified representation,

4 shows a section along the line A-A in Fig. 3 in an enlarged view,

5 shows the individual method steps A, B and C for producing a screw with two helical strands, in a simplified representation,

Fig. 6 is a section along the line A-A in Fig. 5, in an enlarged view, and Fig. 7 shows the individual process steps A, B and C for producing a dowel with two helical strands, in a simplified representation.

FIG. 1 shows various components 1 produced by the method according to the invention. Figure a) shows a countersunk screw, Figure b) a fixing anchor and Figure c) a dowel. Each of these metallic components 1 consists of a head section 2 and two strands 3 and 4 adjoining it in the axial direction, which are formed as helixes or helices.

 The two parallel spaced, longitudinally extending stable strands 3, 4 are intertwined without touching each other.

Each strand 3, 4 is arranged on the head portion 2, that the centroid of the respective strand 3, 4 is shifted to the center line M in an offset direction Z, as shown in Figure 2 for the strand 4. The individual components according to FIG. 1 differ only in the cross-sectional shape and the pitch of the strands 3, 4 and the head section 2.

The extrusion process for the countersunk screw shown in Fig. A) was carried out starting from a blank of solid material. The head section 2 thus also consists of solid material. This is converted at the upper end to a countersunk head 5. As is usual in the case of screws, the countersunk head is connected to a drive, not shown in more detail, e.g. Slot or Torx, equipped for a screw-in.

 To extrude the components 1 shown in Figures b) and c), sleeve-shaped blanks were used.

 The head portion 2 of the anchor according to Fig. B) is formed as a sleeve 6. The two strands 3 and 4 have an oval cross-sectional shape and are comparatively stable. Such an anchor may e.g. be used as a concrete anchor.

The head portion 2 of the anchor according to Fig. C) is also formed as a sleeve 6. The pitch of the helices or the two strands 3, 4 of the anchor according to Fig. C) is significantly smaller than that of the anchor shown in Fig. B). The sleeve 6 of the anchor may be provided with an internal thread for receiving a screw.

In Fig. 2, various variants of prefabricated blanks are shown, which can be used for extruding the components 1 according to the invention.

The blanks 7, T consist of a shank portion 8 and a head portion 2. In Fig. A) is shown a first blank 7 made of solid material, e.g. as a cylindrical rod. This can be made in an upstream Umformstufe by upsetting a wire section.

 In Figure b), a second blank T is also shown, which differs from the blank 7 according to Fig. A) in that the shaft portion 8 already has two cross-sectionally oval strands 8a and 8b, which were formed in upstream forming stages. The two strands 8a, 8b are straight. The center axes M1 of the two strands 8a and 8b are outside the central axis M of the blank 7 '. As will be explained below, the two strands 8a, 8b are respectively formed by extrusion into a helix.

 The third blank 7 shown in Figure c) is a prefabricated metal sleeve 6.

In the case of the blank 7 'shown in FIG. D), the shank portion 8 of the metal sleeve 6 has already been shaped into two strands 8a and 8b which are oval in cross-section, in a manner analogous to that shown in FIG.

The preformed strands 8a and 8b may also be referred to as so-called "legs." The strands 8a and 8b may also have other cross-sectional shapes. The advantage of using blanks with preformed strands is that it is possible to work with lower press forces. In addition, here also the strength of the material used and their compressibility play a role.

In Fig. 3, the individual process steps A, B and C for producing a screw with a helical strand, in chronological order, starting from a blank made of solid blank 7 as a cylindrical rod shown.

The device required for the extrusion process consists of a jaw tool 10 with four movable jaws 1 1, a guide die 12 and a ram 13 over which the required pressing force is applied.

Baking tools with movable jaws for extrusion of metals are known in the art. The tools may be equipped with a different number of jaws, e.g. B. two, three, four or five jaws.

Such a jaw tool consists of an outer, displaceable in the axial direction ring 16, in which the jaws 1 1 are mounted radially movable. The ring 16 is guided on a conical circumferential surface of the jaws 1 1, which tapers in the direction of the opening movement, as seen in step C. The ring 16 has a corresponding with this conical inner surface.

 For opening and closing the jaw tool, the ring 16 is moved either in the pressing direction or in the opposite direction. In the arrangement of the baking tool within a multi-stage press, the movement of the ring 16 is triggered by an unspecified engagement element by the feed movement of the carriage of the multi-stage press. The opening and closing movement of the jaws 1 1 can also be done in other ways.

 The sleeve-shaped guide die 12 has a central opening 12 a, whose cross-sectional shape is adapted to the cross-sectional shape of the blank 7. The blank 7 having a head portion 2 and a shaft portion 8 is inserted into the central opening 12a of the guide die 12 (step A).

 To initiate the pressing process, the press die 13 is delivered and brought into contact with the blank 7.

The jaw tool 10 is structurally designed so that the centroid F of the limited by the inside of the jaws 1 1 outlet opening relative to the longitudinal centerline M of the tool or the blank 7 or component 1 is displaced in an offset direction Z, as shown in FIG. 4. Only by this offset, it is possible during the extrusion process on the formed as a negative inner contour 1 1 a of the jaws 1 1 to deform the shaft portion 8 of the blank 7 to at least one stable strand 4 as a helix. The deformation of the shaft portion to a Coiled strand 4 is shown in simplified form as process step B. Due to the high pressing forces a length change takes place during the extrusion process. The finished component 1 is longer than the blank used 7. After opening the jaws 1 1 of the jaw tool 10, the finished helical component 1 is removed (step C). The punch 13 still takes over the function as an ejector.

If necessary, special forming processes can be subsequently carried out on this component as well, e.g. the deformation of the remaining head portion to a screw head (Fig. 1, Fig. A)).

 FIG. 5 shows the method steps A, B and C for producing a screw with two helical strands starting from a cylindrical blank as a solid material. The jaw tool differs from that according to FIG. 3 in that it has two outlet openings 15. The centroid F (indicated by a dashed line) of each of the two outlet openings 15 is displaced with respect to the center line of the tool or of the component in a respective offset direction Z, as shown in FIG.

 In addition, a stable mandrel 14 is also arranged centrally, which extends up to the end face of the blank 7 pushed into the guide die 12 (method step A). After closing the jaws 1 1 of the baking tool 10 according to process step B and the movement of the ram 13 in the axial direction of the blank is pressed under high pressure through the tool openings 15, wherein due to the helical inner contour synchronously two helical strands 3 and 4 are formed, which wind around the mandrel 14 with the same pitch without getting in touch with each other. After completion of the extrusion process, the mandrel is removed, the jaw tool opened and the component 1 removed.

FIG. 7 shows the method steps A, B and C for producing a dowel. The blank 7 consists of a sleeve 6, which corresponds to the embodiment shown in Fig. 2, Fig. C).

 The sleeve 6 is inserted into the guide die 12 and from the bottom, a mandrel 14 is inserted centrally into the sleeve. The outer diameter of the dome 14 is matched to the inner diameter of the sleeve 6, so that it is inserted with the usual game up to the upper end of the sleeve 6. The mandrel 14 additionally acts as a stabilizing element for the sleeve 6 during the pressing process.

The lower portion of the ram 13 is also formed as a sleeve, as seen in the figure for step A. During the extrusion process, the pointing in the pressing direction annular end face of the punch engages the upper end of the sleeve 6 and pushes it slowly through the tool opening 15. This pushes the sleeve-shaped portion of the ram 13 over the fixed mandrel 14. By the extrusion process, the shaft portion 8 of the sleeve 6 is formed into two helical strands 3 and 4, which wind around the mandrel 14 (step B). After completion of the pressing operation, the mandrel 14 is completely retracted and the jaw tool 10 for demolding of the component 1, the anchor, opened.

Alternatively, for the production of such a dowel, as shown in FIG. 1, FIG. C), a sleeve with two strands 8a and 8b, so-called "legs" according to FIG. 2, d), can also be used as the blank.

 The head section 2 of the dowel shown can be subsequently transformed. The free ends of the helices can be subsequently deformed to a point. All steps can be carried out in a particularly economical manner on a multi-stage press.

 According to the procedure described, components according to the invention can also be produced with three or four helices.

Claims

claims Method for producing metallic components with a shank which is deformed along at least one helix along its longitudinal axis, wherein a blank (7, 7 ') consisting of solid material or a sleeve or as a combination of solid material and sheath is inserted into a guide (12) introduced and subsequently in at least one multi-part jaw tool (10) with at least two movable jaws (1 1) whose inner wall is provided with a negative-shaped helical contour (1 1 a), by extrusion by means of a free end of the blank (7, 7 ') engaging the punch (13) of the shank (8) of the blank by an outlet opening of the jaw tool (10) is pressed, the centroid (F) relative to the center line (M) of the tool (10) or the component (1) in one Offset direction (Z) is shifted, whereby the shaft (8) of the blank (7, 7 ') to at least one stable strand (3 or 4) is converted as a helix. A method according to claim 1, characterized in that the cross-sectional areas of the outlet opening (15) of the jaw tool (10) and the opening (12a) of the guide die (12) differ. Method according to one of claims 1 or 2, characterized in that in an extrusion process spaced synchronously two or more mutually running strands (3, 4) are formed as helices. Method according to one of claims 1 to 3, characterized in that for the extrusion of two or more strands as helices centric into the opening (15) of the jaw tool (10) a stable mandrel (14) is inserted and fixed, and during the pressing process formed helical strands (3, 4) enclose the mandrel (14) and after completion of the pressing operation, the mandrel (14) removed again and the jaw tool (10) is opened for demolding. Method according to one of claims 1 to 4, characterized in that in the center of the blank (7), along the longitudinal center axis, a first straight strand is pressed and at least one second strand (3 or 4), the longitudinal center axis to the longitudinal central axis of the first Stranges is used as a single helix. is pressed, with the helix winds around the first strand during the pressing process. 6. The method according to any one of claims 1 to 5, characterized in that when using a sleeve (6) as a blank of the mandrel (14) to the upper end of the sleeve (6) or hineinhinausragend is inserted and the lower portion of the press ram (13 ) is formed as a sleeve which pushes during the pressing process on the mandrel (14). A method according to any one of claims 1 to 6, characterized in that a preformed blank (7 ') is used which consists of a shank-shaped section (8) with one or more longitudinally extending strands (8a, 8b). 8. The method according to any one of claims 1 to 7, characterized in that all process steps, starting from a cut rod or wire section, carried out in a multi-stage press. 9. The method according to any one of claims 1 to 8, characterized in that the free ends of the strands or helices are deformed to a point. 10. The method according to any one of claims 1 to 9, characterized in that the blank is heated before the extrusion process. 1 1. A method according to any one of claims 1 to 10, characterized in that in two or more strands each formed in the form of a helix whose common outer boundary is larger, smaller or equal to the outer diameter of the blank or the head portion. 12. The method according to any one of claims 1 to 1 1, characterized in that helices are formed with different torsions or pitches. 13. The method according to any one of claims 1 to 12, characterized in that for extrusion of two or more strands (3, 4) as helices a jaw tool (10) with two or more eccentric to the central axis of the blank (7, 7 ') arranged Tool openings is used. 14. The method according to any one of claims 1 to 13, characterized in that the pitch of the helical strands (3, 4) of the manufactured component (1) by subsequent compression of the component (1) is reduced. 15. Device for carrying out the method according to one of claims 1 to 14, comprising at least one multi-part jaw tool (10) with at least two movable jaws (1 1) whose inner wall is provided with a negative-shaped helical contour, a guide (12 ) for receiving a blank (7, 7 ') and a press ram (13) which transmits to the blank (7, 7') an axially acting pressing force, wherein the centroid of the outlet opening of the jaw tool (10) relative to the center line of the Tool (10) or the component (1) in an offset direction (Z) is shifted. 16. The apparatus according to claim 15, characterized in that the cross-sectional areas of the outlet opening of the jaw tool (10) and the opening (12 a) of the guide die (12) are formed differently. 17. Device according to one of claims 15 or 16, characterized in that a fixable mandrel (14) is provided, which is arranged centrally relative to the outlet opening of the jaw tool (10) and up to or into the opening (15) of the baking tool protrudes. 18. Device according to one of claims 15 to 17, characterized in that the guide for receiving the blank (7, 7 ') is part of the baking tool (10) or as a guide die (12) is formed. 19. Device according to one of claims 15 to 18, characterized in that the mandrel (14) extends into the guide or guide die (12). 20. Device according to one of claims 15 to 19, characterized in that the lower portion of the press ram (13) as over the mandrel (14) slidable sleeve is formed. 21. Device according to one of claims 15 to 20, characterized in that the jaw tool (10), guide die (12), ram (13) and optionally the mandrel (14) are arranged within a multi-stage press as flow extrusion unit. 22. Device according to one of claims 15 to 21, characterized in that it comprises a plurality of jaw tools, which are arranged so that the respective centroid of the outlet opening (15) of a single jaw tool (10) relative to the center line of the tool or the component in one Offset direction (Z) is shifted. 23. Device according to one of claims 15 to 22, characterized in that a jaw tool (10) is provided, whose central outlet opening (15) is divided by means of a central insert into a plurality of individual outlet openings, wherein the individual outlet openings are arranged so that their respective center of gravity with respect to the center line of the tool or the component (1) in an offset direction (Z) is shifted. 24. The device according to claim 23, characterized in that the insert is part of the dome (14). 25. Device according to one of claims 15 to 24, characterized in that in addition a central tool opening is provided, via which a straight running strand is formed.