Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
  • B21K1/00—Making machine elements
  • B21K1/56—Making machine elements screw-threaded elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B33/00—Features common to bolt and nut
  • F16B33/02—Shape of thread; Special thread-forms

Definitions

• the invention relates to a method for chipless production of an external thread on workpieces made of metal for use as a stable connection or fastening element, as well as a device suitable for carrying out the method.
• a method for chipless production of an external thread on workpieces made of metal for use as a stable connection or fastening element, as well as a device suitable for carrying out the method.
• two classical types of processes are known, which are used in practice, depending on the size of the thread, the shape of the workpiece and / or the hardness of the metallic material, the rolling or cutting threads.
• the thread can also be produced by means of lathes clamped in lathes, wherein the workpiece is driven.
• the rolling or rolling of external threads on hollow cylindrical workpieces made of metal has gained in mass production in practice the greatest importance.
• a prerequisite for this is that the hollow cylindrical workpieces have a sufficient wall thickness.
• the wall thickness should be at least about 1/5 of the outer diameter / wall thickness on thread rolling on two-roll rolling machines and about 1/8 of the outer diameter / wall thickness on three-roll rolling machines.
• the thread can only be produced by machining or by means of rolling heads on lathes. Producing the thread on multi-spindle turning or tapping machines, however, is more material and time consuming than in a forming production.
• WO2010 / 0307551 A2 a method for chipless production of an external thread on hollow metal workpieces is known, wherein fed within a multi-stage press with a sliding carriage and a stationary tool carrier unit as a starting material wire or rod material and gradually formed into a finished hollow blank.
• the prefabricated hollow blank is inserted into a multi-part jaw tool having a mold cavity, whose inner wall is provided with a thread profile designed as a negative, and introduced in the closed state of the jaw tool in the central opening of the blank at least one mandrel while the blank by of the dome is widened, wherein the contours of the thread profiling are filled by a radial flow of material.
• a blank which has longitudinally extending narrow indentations or recesses at the locations where the jaws of the jawing tool meet.
• the recesses can be changed only slightly in size.
• the design freedom in the thread pressing for producing screw-connection or fasteners with interruptions of the thread or thread-free areas, as required for example for the passage of media or for the introduction of torque by means of wrenches severely limited.
• the invention has for its object to provide a method for non-cutting production of an external thread on workpieces made of metal, which allows different design options in terms of the execution of the workpieces and can be used within a multi-stage press in the thread presses.
• the proposed procedure is provided for producing an external thread on solid or hollow workpieces made of metal by a pressing operation or by expanding a hollow blank by means of a dome.
• thread presses also includes the so-called "expansion”.
• the molded parts according to the invention with external thread are used as stable connection or fastening elements. These may be screws, shafts, fittings, housing components or the like. Act.
• the invention enables the production of different types of fastening or connecting means in a particularly economical manner by means of thread presses.
• the jaw tool used for "pressing” or “expanding” has at least two deliverable jaws with an arcuate inner wall with a thread profiling designed as a negative and at least one fixed or movable jaw with a thread profile-free inner wall.
• This jaw or jaws without thread profiling take over procedurally the function of a guide or Abstützung, on the one hand for the blank and on the other hand for the adjacent deliverable jaws.
• a pressing force can still be generated by means of the unthreaded jaws in order to apply a profiling, embossing, marking or marking to the thread-free surface of the blank, or to produce a function-dependent deformation, such as, for example, a channel with oil drain plugs.
• the inner wall of these jaws may extend beyond the inner wall of the other deliverable jaws in the feed direction.
• a preformed blank which has an inwardly directed, deformed portion, for example in the form of a flattening. Additionally, at the locations where the jaws of the jaw tool meet, the blank has longitudinally extending, narrow indentations or recesses that must be present. The blank is positioned in the open jaw tool so that the recesses lie exactly in the parting plane of the jaws and the deformed section is located exactly in the effective range of the unthreaded jaw. During the closing movement of the jaw tool, the inner wall of this jaw comes into contact with the deformed portion of the blank. It is either due to the deformation, for example is a straight flattening, or intervenes if it is a depression.
• At least one or more threaded sections are pressed on the outer wall or lateral surface of the blank due to the jaws which can be delivered under the action of force. Longitudinally extending threaded portions are interrupted by the recesses formed in the blank.
• the procedure only differs from that described above in that a non-deformable support element is inserted into the hollow-shaped blank, which rests against the inner wall of the blank, at least in the pressing area.
• the support element may be designed as a solid part, which fills the cavity, or as a tubular part. In its geometry, however, it must be designed so that it fits accurately into the cavity of the preformed blank can be inserted.
• At least one or more threaded sections are pressed over the closing movement of the deliverable jaws on the outer wall or lateral surface of the blank.
• the jaw tool is closed before or after insertion or insertion of the preformed blank and the blank is secured against axial displacement.
• the pre-formed blank must be positioned again as already mentioned. Under the action of force, an expanding mandrel is inserted into the blank, in order to fill the negative profiled thread profiling on the inner wall of the deliverable jaws by a flow of material and thus to produce the corresponding external thread.
• the deformed portion of the blank which is to be unthreaded may be in the form of a straight surface or flattening and extend over the entire length or only a portion of the blank.
• the blank may be preformed by deep drawing or other upsetting and / or extrusion steps.
• An advantage of the invention is that blanks having geometrically different cross-sectional shapes, e.g. Triangle, square, hexagon or combinations of straight, oblique and arcuate sections, by means of threaded presses an external thread can only be applied to certain surfaces.
• the blank can, for example, in a preforming step to a cross-sectional shape with two opposite arcuate sections and two opposite straight or flattened sections are formed, wherein only on the arcuate sections an external thread is generated.
• the deliverable jaws for generating the external thread can be arranged side by side or opposite each other.
• the movement of the jaws can take place in the axial and / or radial direction.
• the thread profile-free jaw In a movable arrangement of the thread profile-free jaws they are moved synchronously with the other jaws.
• the thread profile-free jaw can be part of the die or jaw guide as a fixed component.
• a suitable device for carrying out the method consists at least of a jaw tool with a plurality of movable jaws, which are guided in an annular guide on wedge-shaped guide surfaces and movable in the axial and / or radial direction. At least two jaws have an arcuate inner wall with a trained as a negative thread profiling. At least one other fixed or movable jaw has a thread profile-free inner wall. In a movable embodiment of this jaw it rests against the blank and is displaceable mainly in the axial direction.
• the jaw guide is surrounded by a reinforcing ring.
• All movable jaws are movable from an open position to a closed position and vice versa and are in the closed position on the blank. Between jaw guide and jaws, a relative movement takes place.
• a hollow blank e.g. an expanding mandrel acting under the action of force, which causes a widening process at least only at the points where there is a thread profiling designed as a negative.
• an axially movable, insertable into the hollow blank, non-deformable support member is provided, which rests in the inserted state on the inner wall of the blank.
• All forming processes for the blank and the thread pressing can be carried out within a multi-stage press.
• Fig. 2 shows a section along the line A-A in Fig. 1, Fig. A) and Fig. B) in an enlarged
• FIG. 3 shows the individual process steps a), b), c) and d) for the production according to the invention of a hollow part with external thread, in a simplified representation, 4 shows a section along the line AA in Fig. 3, Fig. B) and Fig. C) in an enlarged view,
• FIG. 6 shows a section according to the line A-A in Fig. 5, Fig. A) and Fig. B) in an enlarged view
• Fig. 7 shows another embodiment of a baking tool with four movable jaws, as a cross-sectional view
• Fig. 8 shows a further embodiment of a jaw tool with two movable jaws and a stationary or stationary jaw, as a cross-sectional view.
• Fig. 2 The associated sectional view according to the line A-A to stage a) and b) can be seen in Fig. 2.
• the preformed blank 1 is inserted into an open jaw tool, which consists of two axially and radially displaceable jaws 4, each having an arcuate inner wall with a trained as a negative thread profiling 6. Above the jaw tool, a stationary die upper part 2 is arranged.
• the two jaws 4 are arranged directly next to each other.
• the third jaw 5 has a smooth inner wall without thread profiling and is essentially only axially displaceable.
• the jaws 4 and 5 are movably arranged in a jaw guide 3, which is surrounded by a reinforcing ring not shown in detail.
• the radial and axial delivery of the jaws 4 via wedge-shaped guide surfaces as clearly visible in Fig. 1.
• the cross-sectional shape of the lower portion of the blank 1 is shown in Fig. 2, Fig. A) watch.
• the blank 1 has three longitudinally extending narrow recesses or recesses 7, which are located at the points where the jaws 4, 5 meet. These can only be seen in FIG. 2.
• the closing process for the jaws 4, 5 of the baking tool is triggered by a correspondingly high force on the jaw guide 3.
• This embodiment is shown in the drawing.
• the feed force for the movement of the jaws can also be done via the jaws, in this case the jaw guide remains in its position. In practical use, this embodiment is preferred.
• the two jaws 4 with a thread profiling designed as a negative are radially delivered and cause the formation of the thread on the shank of the blank 1, as shown in Figures b) in Figs. 1 and 2.
• the unthreaded jaw 5 does not change its position.
• the shank of the blank or of the still unfinished screw has a threaded section over a circumference of about 250 ° and a flattened section (fig. 2, fig. B republic
• the head of the molding or the screw can then be converted later in other known forming stages still to its final shape.
• FIGS. 3 and 4 show the pressing of an external thread onto the shank of a hollow-shaped part.
• the structure of the tool is analogous as explained above.
• the pre-formed by deep drawing or extrusion compression blank 11 has a hollow shaft and an annular collar 20 and is inserted into the jaw tool with the jaws 14 and 15 (Fig. A)), which are guided in the jaw 13 tion movable.
• a movable punch 18 is still arranged, which is guided in the Matrizenoberteil 12. The punch 18 is moved downwards and remains in this position (Fig. B)).
• the baking tool is still open.
• the jaw tool is closed, wherein the formed as a negative thread profiling 16 of the jaws 14 in the shank of the blank 11 to press the threaded portions.
• the lower, protruding into the shaft of the blank part of the punch 18 serves as a support element.
• the hollow shaft of the blank 11 also has three longitudinally extending narrow indentations or recesses 17.
• FIGS. 5 and 6 show the production of the external thread by means of a widening mandrel 28.
• the blank 21 has a hollow shaft and an annular collar 30 and is inserted into the jaw tool with the jaws 24 and 25 and this closed (Fig. A).
• the construction of the jaw tool corresponds to the previously described embodiment the jaws 24, 25 are in touching contact with the shank of the blank 21 in the closed state
• the punch is pressed with the expanding mandrel 28 into the hollow shaft and thereby the external thread is formed (FIG. In Fig. C) the final demoulding is shown.
• a jaw tool is shown having four movable jaws 34 and 35, which are respectively arranged opposite to each other.
• the arcuate inner wall of the two jaws 34 is provided with a thread profiling designed as a negative.
• the other two jaws 35 are thread-free.
• the blank 31 has two opposite arcuate portions and two opposite flattened straight portions which are inwardly directed with respect to the circular shape.
• annular reinforcement 39 is arranged, since relatively high forces occur during thread pressing.
• the blank has, at the locations where the jaws 34, 35 of the jaw tool meet, longitudinally extending narrow recesses or recesses 37.
• the four recesses are arcuate in cross-section.
• the front planar portion of the jaws 35 abuts against the respective flattened side of the blank 31 during the closing movement of the jaw tool.
• FIG. 8 in itself corresponds to the sectional view shown in FIG. 2, only with the difference that only the two jaws 44 are movably arranged with a thread profiling designed as a negative.
• the third, unthreaded jaw is as a stationary component part of the jaw guide 43.
• the figure a) shows the jaw tool in the open and the figure b) in the closed state.
• the blank 41 also has three recesses 47.
• the blanks and molded parts produced with an external thread correspond to those according to FIGS. 1 and 2.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Forging (AREA)

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Citations (9)

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• 2012
  • 2012-04-12 DE DE102012103179A patent/DE102012103179A1/de not_active Withdrawn
• 2013
  • 2013-03-27 TW TW102110786A patent/TW201347872A/zh unknown
  • 2013-04-08 WO PCT/DE2013/100125 patent/WO2013152758A1/fr not_active Ceased

Patent Citations (9)

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