EP0940228B1 - Screw extractor - Google Patents

Screw extractor Download PDF

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Publication number
EP0940228B1
EP0940228B1 EP99104364A EP99104364A EP0940228B1 EP 0940228 B1 EP0940228 B1 EP 0940228B1 EP 99104364 A EP99104364 A EP 99104364A EP 99104364 A EP99104364 A EP 99104364A EP 0940228 B1 EP0940228 B1 EP 0940228B1
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EP
European Patent Office
Prior art keywords
screw
flank
extractor
stump
notch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP99104364A
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German (de)
French (fr)
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EP0940228A2 (en
EP0940228A3 (en
Inventor
Reiner Ranft
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Robert Schroeder GmbH and Co KG
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Robert Schroeder GmbH and Co KG
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Application filed by Robert Schroeder GmbH and Co KG filed Critical Robert Schroeder GmbH and Co KG
Publication of EP0940228A2 publication Critical patent/EP0940228A2/en
Publication of EP0940228A3 publication Critical patent/EP0940228A3/en
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Publication of EP0940228B1 publication Critical patent/EP0940228B1/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25BTOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B27/00Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for
    • B25B27/14Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for for assembling objects other than by press fit or detaching same
    • B25B27/18Hand tools, specially adapted for fitting together or separating parts or objects whether or not involving some deformation, not otherwise provided for for assembling objects other than by press fit or detaching same withdrawing broken threaded parts or twist drills

Definitions

  • the invention relates to screw extractors according to the preamble of claim 1.
  • screw extractors are known from DE-PS 625 735.
  • Such a screw extractor tries to from the torn screw stump by means of oversized chip detection to produce a rotary joint. You go from the consideration that an oversized chip detection too a tight fit of the tool in the screw stump.
  • a screw extractor assumed the screw-in zone to a pinching Deformation of the edge of the hole in the screw stump leads to so long until the torque-increasing measures Rotational blockage of the screw extractor achieved in its bore becomes.
  • the advantage of the invention is that the thread core diameter almost completely or completely preserved remains so that the one at risk of torsional fracture Place of the screw extractor not or only insignificantly is weakened.
  • the invention is to be distinguished from so-called Chip drainage channels, as usual with taps and are known.
  • the invention is based on the fact that only one local chip removal in the area of the screwed-in screwing zone not happened.
  • the squeezing flank of the notch runs flat, so to speak into the threaded zone in the screw zone Screw stump on. This takes place at most slight plastic deformation of the inner edge areas in the Screw stump where the further squeezing flanks are then finalize.
  • the main direction of loading is in the screw stump practically in the circumferential direction as soon as the crushing edges have reached a certain impression depth.
  • the crushing flanks therefore do not lead to cutting to a upsetting effect, which is ultimately a perimeter stop in the screw stump.
  • the perimeter stop is formed between the crushing flank and the compressed one Counter surface in the screw stump.
  • the circumference stops at a reduced screwing depth of the screw extractor a torsionally rigid connection between screw extractor and Screw stump.
  • the crushing edges are mainly from the triangular surfaces of the cut turns, with their tips immediately after approaching the Work the screw stump into the material of the screw stump. Larger areas of the area are becoming increasingly common Triangular surfaces in the pressure position, so that very short angles of rotation be covered until they are fixed.
  • The is essential for the invention Combination of a variety of close to each other, preferably immediately adjacent triangular surfaces in connection with a rake angle that is not less than 70 degrees and not should be greater than 110 degrees.
  • a rake angle that is taken into account is preferred the manufacturing tolerances should be 90 degrees.
  • Tightly adjacent triangular surfaces in the sense of the present Registration are those whose width at the foot is greater than is the distance between two adjacent triangular surfaces.
  • a such a constellation is obtained through a multi-course Pointed thread, the individual turns of which are practically immediate lie next to each other without the foot areas of the Coils of flat zones with the core diameter at the respective Thread point occur.
  • This combination therefore leads primarily to the desired crushing effect, because the triangular cross sections of the individual threads of the thread with increasing broadening of your Dig the front surface into the material of the screw stump. This creates an at least three-dimensional plastic one Deformation of the material of the screw stump caused by sole chip formation cannot be described.
  • the outer geometry of the screw extractor remains obtained in principle according to the present invention. It will only longitudinal recesses running across the turn removed from the screw-in zone.
  • the recess depth affects the polar section modulus the remaining cross section practically not or only slightly.
  • Chip formation should be avoided in any case in order to a defined state of engagement between the crushing flank and Screw stump to come.
  • the invention uses the basic idea that with The screw extractor is increasingly drawn into the screw stump larger diameter areas of the screw zone in the Hole in the screw stump. To this The turned core is expanded in this way axial bore while maintaining a relative twist between screw extractor and screw stub.
  • this inner edge zone now runs Effect the pinch edge in and will -da it has the higher hardness - in the material of the screw stump push in circumferentially.
  • the squeeze edge therefore causes a combinatorial Effect due to disproportionate deformation of the axial bore, because in addition to the deforming effect of the screw-in zone in the radial direction also in the circumferential direction local deformation. It therefore arises from one certain screw-in depth a torsionally rigid rotating connection piece, which is only on the outer circumference of the torn off Screw stub is held during the breakaway torque over the screw extractor into the rotating connection piece is initiated.
  • the defined torsionally rigid connection between Screw extractor and screw stub can be done this way easily the breakaway torque of the torn screw stump can be reached, so that the screw stump is easy can be turned out of its threaded seat.
  • the notch to lay only on the basic diameter of the turns and especially when unscrewing screws with a small diameter, e.g. for screws up to 8 mm, the notches no deeper than about 2/3 of the tooth height of the turns.
  • the optimal depth of the notch can also be the angle between the crushing flank and the tangent to be varied on the peripheral edge of the squeeze flank that the greatest possible burial effect without peeling effect on the axial bore.
  • the squeezing flank should preferably be counter to the screwing direction of the screw extractor backwards or in The screwing direction can be moved to the front in the center. This leads to an increased digging effect and also with crushed edges, the cutting effect due to its angular geometry would have to the primary burial effect. In each Trap should be the formation of chips in the screw stump be avoided.
  • the off-center offset to the front or to the rear should at most be so large that the Angle between the crushing flank and the tangent to the Circumferential edge of the crushing flank not less than 70 degrees and no greater than 110 degrees.
  • Such squeezing flanks can e.g. with side milling cutters getting produced. You can run the entire length of the Screw-in zone run or only locally. By using it the indentations run from disc milling cutters their axial lower and upper ends into those there Turns out. Nevertheless, the desired effect is without achieved further. Because the local upsetting of the screw stump due to the running crushing edge in the 1/10 mm range is, in principle, it is not necessary either Notch run over the entire length of the screw-in zone allow.
  • the figures show a screw extractor 1 for unscrewing of screw stumps 10 torn screws.
  • the screw extractor 1 has at its upper end a drive shaft 2, which is used to put on a tap wrench serves. Such screw extractors are always only manually inserted.
  • the drive shaft 2 continues forward into one oblong-cylindrical transition area 3.
  • the transition area 3 no thread is provided.
  • the transition area 3 is straight cylindrical.
  • the entire screw zone 4 runs like a cone the cone angle 6 tapers towards the tip 5.
  • This cone tip is such a screw extractor 1 in the axial Drilled hole 11 of the torn screw stub 10. Since the direction 8 of the winding 7 opposite to Thread direction 9 of the torn screw stub 10 runs, can the broken screw stump 10 screwed out of its threaded hole with some skill become.
  • the notch 12 runs across several turns 7 and points in the direction of rotation of the rotating composite, consisting of Screw extractor 1 and screw stub 10, one in the Axial bore 11 of the screw stump 10 rising crushing flank 14 on.
  • the direction of rotation of the rotating joint 1 + 10 coincides with the screwing-in direction of the screw-in zone 4.
  • the notch 12 has a leading edge 15 with which the notch 12 incorporated into the material of the screw stump 10 and a trailing edge 16, which is in the direction of rotation of the Screw extractor 1 prepared this effect.
  • the rising edge 15 consequently determines the depth 13, with which the notch 12 in the material of the screw extractor is introduced.
  • This insertion depth 13 should practically no deeper than the thread height 17, that is half the difference between the outer diameter 18 of the screw extractor and the basic diameter 19.
  • the screw extractor Since the screw extractor is used correctly while squeezing the edge material of the axial bore 11 worked into the screw stump 10, from the rising flank 15 of a certain screw-in depth, which is referred to here as the squeeze flank, with increasing increasing engagement zone in the wall of the screw stump 11 and pushes the material of the screw stump like this a long time before the screw extractor 1 in the circumferential direction is rigidly connected. This crucial phase the unscrewing process ultimately determines success. As long as the breakaway torque of the screw stump 10 has not yet been exceeded is, the screw extractor 1 must continue in the Material of the screw stump.
  • the figures show exemplary embodiments, where the depth 13 of the notch 12 is no more than that Double the thread height is 17.
  • Figure 2 shows an embodiment, at which is the longitudinal direction of the notch 12 with the axial direction of the screw extractor coincides.
  • FIG 3 shows an exemplary embodiment, in which the notch 12 is practically perpendicular to the Direction of the turns 7 is.
  • the figures show the special case that the Crimp edge 14 offset off-center by a distance (20) is. This means that the rising edge 15 is not on their largest possible lever arm engages the axial bore 11. There is therefore also a certain additional squeezing effect, because the undesirable cutting effect the rising edge 15 is additionally prevented.
  • the off-center offset 20 can also be in the millimeter range lie.
  • Such notches 12 serve the purpose of the invention fully.
  • Crimp edge 15 with a small radius of up to pass about 2 mm into the trailing flank 16.
  • Fig. 3 shows an embodiment, at which the squeeze edge 14 is part of a circular segment Bleed is how easy it is by use a side milling cutter in such screw extractors 1 can be produced.
  • Fig. 2 also shows additional measures for prevention a cutting effect caused by the crushing edge 14 should not be achieved exactly. For this purpose it closes the squeeze flank 14 with the tangent 21 on its peripheral edge an angle 22, which is 90 degrees here.
  • the only decisive factor is the use of the deformation of the Material of the screw stump due to the burr effect the pinch edge 14 causes.

Abstract

The screw extractor (1) has a notch to increase the torque introduced into the screw stub. This notch has a clamp flank (14) as leading flank, which is formed by a number of closely neighbouring faces with the triangular cross sections of a multi-pitch triangular thread. The notch cuts across the threads (7) non-centrally and offset, so that the angle between the clamp flank and the tangent on the circumferential edge of the clamp flank is 90 degrees plus/minus 20 degrees .

Description

Die Erfindung betrifft Schraubenausdreher nach Oberbegriff von Anspruch 1. Derartige Schraubenausdreher sind bekannt aus DE-PS 625 735.The invention relates to screw extractors according to the preamble of claim 1. Such screw extractors are known from DE-PS 625 735.

Mit einem derartigen Schraubenausdreher wird versucht, aus dem abgerissenem Schraubenstumpf mittels übergroßer Spanerfassung ein Drehverbundstück herzustellen. Dabei geht man von der Überlegung aus, daß eine übergroße Spanerfassung zu einem Festsitz des Werkzeugs im Schraubenstumpf führen muß.Such a screw extractor tries to from the torn screw stump by means of oversized chip detection to produce a rotary joint. You go from the consideration that an oversized chip detection too a tight fit of the tool in the screw stump.

Andererseits will man die auseinander treibende Keilwirkung des Gewindes vermeiden. Dies erreicht man dadurch, daß zwischen den Windungen vorbestimmte Flächen freigelassen werden.On the other hand, you want the wedge effect to drift apart avoid the thread. This is achieved in that predetermined areas are left between the turns.

Man versucht also, die Spanerfassung so vorzubestimmen, daß die anwachsende Spandicke zu einem Festsitz des Werkzeugs im Schraubenstumpf führt. Dabei muß ergänzend die Keilwirkung der Windungen unterbunden werden. Flankiert wird dieses Maßnahmenbündel von einem mehrgängigen Trapezgewinde mit dazwischen befindlichen Freiflächen, welche die Keilwirkung des Gewindes unterbinden sollen. Hieraus ergibt sich allerdings das Problem, daß ein sehr großer Drehwinkel bis zum entstanden Drehverbundstück notwendig ist, weil lediglich ein geringer axialer Längenanteil des Schraubenstumpfs der Spanbildung unterworfen wird. Das Drehverbundstück setzt folglich ein entsprechend tiefes Eingraben der Schneidkanten in den Schraubenstumpf voraus. Der große notwendige Drehwinkel macht daher einen erheblichen Teil des ansich positiven Spanbildungseffekts wieder zunichte.So you try to pre-determine the chip detection that the increasing chip thickness becomes a tight fit of the tool leads in the screw stump. The wedge effect must also be added the turns are prevented. This bundle of measures is flanked of a multi-start trapezoidal thread with in between located open spaces, which the wedge effect of the Should prevent threads. However, this results in the problem that a very large angle of rotation up to Twist joint is necessary because only a small one axial part of the length of the screw stump during chip formation is subjected. The swivel joint consequently sets a correspondingly deep digging of the cutting edges into the Screw stub ahead. The large necessary angle of rotation makes hence a significant part of the positive chip formation effect again nullified.

Aus der DE-OS 43 34 471 ist es bekannt, in der Einschraubzone Maßnahmen vorzusehen, welche der Erhöhung des in den Schraubenstumpf eingeleiteten Drehmoments dienen.From DE-OS 43 34 471 it is known in the screw-in zone To take measures to increase the serve the torque applied.

Hierunter können unter anderem vorspringende Noppen, Stege oder dergleichen fallen, die sich bei einem Einschrauben der Einschraubzone in das verbleibende Material des Schraubenstumpfs einarbeiten.These can include protruding knobs, Bridges or the like fall when screwing in the screwing zone into the remaining material of the Work in the screw stump.

Damit wird ebenfalls erreicht, daß sich der Schraubenausdreher im Schraubenstumpf drehstarr festsetzt, bevor die zum Ausdrehen des Drehverbundstücks, bestehend aus Schraubenausdreher und Schraubenstumpf, an sich erforderliche Einschraubtiefe erreicht ist.This also ensures that the screw extractor locked in the screw stub before the for unscrewing the rotating connection piece, consisting of screw extractor and screw stub, screw-in depth required per se is reached.

Hierdurch unterbleibt die kritische Aufspreizung der Restwandstärke des Schraubenstumpfes insbesondere im oberen Aufspreizbereich, so daß keine zusätzliche Anpressung des Schraubenstumpfs an seinem Gewinde erfolgt.As a result, the critical spreading of the Remaining wall thickness of the screw stump, especially in the upper one Spreading area so that no additional pressure on the Screw stump is done on its thread.

Grundsätzlich wird daher von einem Schraubenausdreher ausgegangen, dessen Einschraubzone zu einer verquetschenden Verformung des Bohrungsrandbereichs im Schraubenstumpf führt, so lange bis durch die Drehmoment erhöhenden Maßnahmen eine Drehblockade des Schraubenausdrehers in seiner Bohrung erzielt wird.Basically, therefore, a screw extractor assumed the screw-in zone to a pinching Deformation of the edge of the hole in the screw stump leads to so long until the torque-increasing measures Rotational blockage of the screw extractor achieved in its bore becomes.

Da grundsätzlich von der Tatsache ausgegangen werden muß, daß Drehmoment erhöhende Maßnahmen zu einer Verringerung der Werkstoffanstrengung im Schraubenausdreher führen, soll die Erfindung einen Vorschlag unterbreiten, mit dem unter allerhöchstens geringer Beeinträchtigung des polaren Widerstandsmomentes bei einen derartigen Schraubenausdreher die spezifische Belastung auf die einzelnen Gewindegänge der Vielzahl unterschiedlicher Windungen verringert ist. Die Lösung dieser Aufgabe erfolgt durch die Maßnahmen des Anspruchs 1.Since the fact is generally assumed that torque-increasing measures must lead to a reduction of material stress in the screw extractor the invention make a proposal with which at most little impairment of the polar moment of resistance with such a screw extractor specific load on the individual threads of the Variety of different turns is reduced. The solution this task is accomplished through the measures of the claim 1.

Aus der Erfindung ergibt sich der Vorteil, daß der Gewindekerndurchmesser nahezu vollständig oder vollständig erhalten bleibt, so daß die durch Torsionsbruch gefährdete Stelle des Schraubenausdrehers nicht oder nur unwesentlich geschwächt wird.The advantage of the invention is that the thread core diameter almost completely or completely preserved remains so that the one at risk of torsional fracture Place of the screw extractor not or only insignificantly is weakened.

Dabei ist die Erfindung abzugrenzen von sogenannten Späneabflußkanälen, wie sie bei Gewindeschneidern üblich und bekannt sind.The invention is to be distinguished from so-called Chip drainage channels, as usual with taps and are known.

Die Erfindung geht nämlich davon aus, daß eine auch nur lokale Spanabhebung im Bereich der eingedrehten Einschraubzone nicht erfolgt.The invention is based on the fact that only one local chip removal in the area of the screwed-in screwing zone not happened.

Die Quetschflanke der Einkerbung läuft sozusagen flächig in die von der Einschraubzone ausgeprägte Gewindezone im Schraubenstumpf auf. Hierdurch erfolgt eine allerhöchstens geringe plastische Verformung der inneren Randbereiche im Schraubenstumpf, wo sich die weiter auflaufenden Quetschflanken dann endgültig festsetzen.The squeezing flank of the notch runs flat, so to speak into the threaded zone in the screw zone Screw stump on. This takes place at most slight plastic deformation of the inner edge areas in the Screw stump where the further squeezing flanks are then finalize.

Dabei geht die Hauptbelastungsrichtung im Schraubenstumpf praktisch in Umfangsrichtung, sobald die Quetschflanken eine gewiße Einprägtiefe erreicht haben.The main direction of loading is in the screw stump practically in the circumferential direction as soon as the crushing edges have reached a certain impression depth.

Die Quetschflanken führen daher nicht zu einem Schneidsondern zu einem Staucheffekt, der letztlich einen Umfangsanschlag im Schraubenstumpf hervorruft. Der Umfangsanschlag wird gebildet zwischen der Quetschflanke und der gestauchten Gegenfläche im Schraubenstumpf. Der Umfangsanschlag führt bei einer verringerten Einschraubtiefe des Schraubenausdrehers zu einer drehstarren Verbindung zwischen Schraubenausdreher und Schraubenstumpf. Die Quetschflanken werden hauptsächlich von den Dreiecksflächen der aufgeschnittenen Windungen gebildet, die sich mit ihren Spitzen sofort nach der Annäherung an den Schraubenstumpf in das Material des Schraubenstumpfes einarbeiten. Dabei geraten zunehmend größere Flächenbereiche der Dreiecksflächen in Andruckposition, so daß sehr kurze Drehwinkel bis zum Festsetzen zurückgelegt werden.The crushing flanks therefore do not lead to cutting to a upsetting effect, which is ultimately a perimeter stop in the screw stump. The perimeter stop is formed between the crushing flank and the compressed one Counter surface in the screw stump. The circumference stops at a reduced screwing depth of the screw extractor a torsionally rigid connection between screw extractor and Screw stump. The crushing edges are mainly from the triangular surfaces of the cut turns, with their tips immediately after approaching the Work the screw stump into the material of the screw stump. Larger areas of the area are becoming increasingly common Triangular surfaces in the pressure position, so that very short angles of rotation be covered until they are fixed.

Von wesentlicher Bedeutung für die Erfindung ist die Kombination aus einer Vielzahl von zueinander dicht, vorzugsweise unmittelbar benachbarten Dreiecksflächen in Verbindung mit einem Spanwinkel, der nicht kleiner als 70 Grad und nicht größer als 110 Grad sein soll.The is essential for the invention Combination of a variety of close to each other, preferably immediately adjacent triangular surfaces in connection with a rake angle that is not less than 70 degrees and not should be greater than 110 degrees.

Bevorzugt wird ein Spanwinkel, der unter Berücksichtigung der Fertigungstoleranzen bei 90 Grad liegen soll.A rake angle that is taken into account is preferred the manufacturing tolerances should be 90 degrees.

Dicht benachbarte Dreiecksflächen im Sinne der vorliegenden Anmeldung sind solche, deren Breite am Fuß größer als der Abstand zweier benachbarter Dreiecksflächen ist. Eine derartige Konstellation erhält man durch ein mehrgängiges Spitzgewinde, dessen einzelne Windungen praktisch unmittelbar nebeneinander liegen, ohne daß zwischen den Fußbereichen der Windungen Flachzonen mit dem Kerndurchmesser an der jeweiligen Gewindestelle auftreten. Diese Kombination führt daher vorrangig zu dem angestrebten Quetscheffekt, weil sich die dreiecksflächigen Querschnitte der einzelnen Gewindegänge des Spitzgewindes unter zunehmender Verbreiterung Ihrer Frontfläche in das Material des Schraubenstumpfs eingraben. Es entsteht daher eine zumindest dreidimensionale plastische Verformung des Materials des Schraubenstumpfs, welche durch alleinige Spanbildung nicht beschrieben werden kann. Es sind nämlich die erheblichen plastischen Verformungsanteile im Material des Schraubenstumpfs zu berücksichtigen, weil die plastischen Anteile zu einem raschen Festsetzen des Schraubenausdehers im Schraubenstumpf führen. Die plastische Verformung unter Druck führt zu überproportional ansteigenden Widerstandskräften im Schraubenstumpf. Hierfür werden einerseits die Verfestigungseffekte im Material selbst als auch der mindestens dreidimensionale Spannungszustand im Bereich der Quetschflanken verantwortlich gemacht. Tightly adjacent triangular surfaces in the sense of the present Registration are those whose width at the foot is greater than is the distance between two adjacent triangular surfaces. A such a constellation is obtained through a multi-course Pointed thread, the individual turns of which are practically immediate lie next to each other without the foot areas of the Coils of flat zones with the core diameter at the respective Thread point occur. This combination therefore leads primarily to the desired crushing effect, because the triangular cross sections of the individual threads of the thread with increasing broadening of your Dig the front surface into the material of the screw stump. This creates an at least three-dimensional plastic one Deformation of the material of the screw stump caused by sole chip formation cannot be described. There are namely the considerable plastic deformation components in the Material of the screw stump to be taken into account because of the plastic parts for a quick fixing of the screw expander lead in the screw stump. The plastic deformation under pressure leads to disproportionately increasing Resistance forces in the screw stump. For this, on the one hand the solidification effects in the material itself as well the at least three-dimensional state of stress in the area the squeezing flanks blamed.

Dabei bleibt die äußere Geometrie der Schraubenausdreher gemäß vorliegender Erfindung prinzipiell erhalten. Es werden lediglich quer über die Windung verlaufende Längsausnehmungen aus der Einschraubzone herausgenommen.The outer geometry of the screw extractor remains obtained in principle according to the present invention. It will only longitudinal recesses running across the turn removed from the screw-in zone.

Die Ausnehmungstiefe beeinträchtigt das polare Widerstandsmoment des verbleibenden Querschnitts praktisch nicht oder nur geringfügig.The recess depth affects the polar section modulus the remaining cross section practically not or only slightly.

Während also der Gewindekerndurchmesser vollständig oder nahezu vollständig erhalten bleibt, der Gewindeaußendurchmesser vollkommen erhalten bleibt und die durch die Ausnehmung entstehende Quetschflanke nicht über den Gewindeaußendurchmesser hervorsteht, können auf herkömmliche Art hergestellte Schraubenausdreher mit einfachen Mitteln im Sinne der Erfindung verbessert werden.So while the thread core diameter completely or the outer thread diameter remains almost completely intact remains completely intact through the recess resulting squeeze flank does not exceed the thread outer diameter protrudes, can be manufactured in a conventional manner Screw extractor with simple means in the sense of the invention be improved.

Um zu einer Quetschflanke nach dieser Erfindung zu kommen, bedarf es lediglich eines quer über die Windung verlaufenden Anschnitts der Windung so, daß die Quetschflanke mit der Tangente an ihre Umfangskante einen Winkel von etwa 90 Grad +- 20 Grad einschließt.In order to arrive at a pinch edge according to this invention, all that is needed is one that runs across the winding Cut the winding so that the crushing flank with the tangent to its peripheral edge forms an angle of approximately 90 Includes + - 20 degrees.

Unter diesen Voraussetzungen ist für einen optimalen Auflauf der Quetschflanke im Material des Schraubenstumpfes gesorgt, ohne daß die Gefahr einer Spanbildung entsteht. Spanbildung sollte in jedem Fall vermieden werden, um zu einem definierten Eingriffzustand zwischen Quetschflanke und Schraubenstumpf zu kommen.Under these conditions is for an optimal Accumulation of the crushing flank in the material of the screw stump taken care of without the risk of chip formation. Chip formation should be avoided in any case in order to a defined state of engagement between the crushing flank and Screw stump to come.

Es ist daher nach Möglichkeit kein Spanwinkel anzustreben sondern unter Berücksichtigung der sonstigen Schraubenausdrehergeometrie ein Staucheffekt, den die Quetschflanke durch Auflaufen am Schraubenstumpf hervorruft.Therefore, if possible, no rake angle should be aimed for but taking into account the other screw extractor geometry a crushing effect that the crushing flank caused by collision with the screw stump.

Die Erfindung nutzt nämlich den Grundgedanken, daß mit Einziehen des Schraubenausdrehers in den Schraubenstumpf zunehmend durchmessergrößere Bereiche der Einschraubzone in die Bohrung des Schraubenstumpfs hineingezwängt werden. Auf diese Weise erfolgt eine Expansion des eingedrehten Kerns in der axialen Bohrung, während zugleich eine relative Verdrehung zwischen Schraubenausdreher und Schraubenstumpf vorliegt.The invention uses the basic idea that with The screw extractor is increasingly drawn into the screw stump larger diameter areas of the screw zone in the Hole in the screw stump. To this The turned core is expanded in this way axial bore while maintaining a relative twist between screw extractor and screw stub.

Im Prinzip entsteht daher eine Relativdrehung des Schraubenausdrehers im Schraubenstumpf im Sinne zunehmender Materialbeanspruchung mit expandierendem Charakter. Das Einziehen der Einschraubzone folgt nicht schneidend sondern quetschend und es wird daher kein Material des Schraubenstumpfes abgetragen sondern lediglich verdrängt.In principle, therefore, a relative rotation of the Screw extractor in the screw stump in the sense of increasing Material stress with an expanding character. The moving in the screw-in zone does not follow cutting but instead squeezing and therefore there is no material of the screw stump worn away but only displaced.

Hierdurch erfolgt in der Innenzone des Schraubenstumpfes eine zunehmend plastische Verformung, die letztlich zu einer Verfestigung der Innenrandzone führen kann.This takes place in the inner zone of the screw stump an increasingly plastic deformation that ultimately leads to a Consolidation of the inner edge zone can result.

In diese innere Randzone läuft nun infolge des expandierenden Effekts die Quetschkante hinein und wird sich -da sie die höhere Härte aufweist- in das Material des Schraubenstumpfes umfangsmäßig hineindrücken. Dadurch erfolgt eine weitere Verformung des Randzonenbereichs der Axialbohrung, die zu einem zunehmenden Drehmomentanstieg am Schraubenstumpf führt. Die Quetschflanke bewirkt daher einen kombinatorischen Effekt durch überproportionale Verformung der Axialbohrung, weil sie zusätzlich zu der verformenden Wirkung der Einschraubzone in Radialrichtung auch in Umfangsrichtung zu einer lokalen Verformung führt. Es entsteht daher ab einer gewißen Einschraubtiefe ein in sich drehstarres Drehverbundstück, welches lediglich noch am Außenumfang von dem abgerissenen Schraubenstumpf festgehalten wird, während das Losbrechmoment über den Schraubenausdreher in das Drehverbundstück eingeleitet wird.As a result of the expanding, this inner edge zone now runs Effect the pinch edge in and will -da it has the higher hardness - in the material of the screw stump push in circumferentially. This results in a further deformation of the edge zone area of the axial bore, which leads to an increasing torque increase at the screw stump leads. The squeeze edge therefore causes a combinatorial Effect due to disproportionate deformation of the axial bore, because in addition to the deforming effect of the screw-in zone in the radial direction also in the circumferential direction local deformation. It therefore arises from one certain screw-in depth a torsionally rigid rotating connection piece, which is only on the outer circumference of the torn off Screw stub is held during the breakaway torque over the screw extractor into the rotating connection piece is initiated.

Durch die definiert drehstarre Verbindung zwischen Schraubenausdreher und Schraubenstumpf kann auf diese Weise leicht das Losbrechmoment des abgerissenen Schraubenstumpfs erreicht werden, so daß anschließend der Schraubenstumpf einfach aus seinem Gewindesitz herausgedreht werden kann.The defined torsionally rigid connection between Screw extractor and screw stub can be done this way easily the breakaway torque of the torn screw stump can be reached, so that the screw stump is easy can be turned out of its threaded seat.

Dabei kommt es im wesentlichen nur auf eine Quetschflanke an, die sehr flach ist. Da die Tiefe der Quetschflanke den Gewindekerndurchmesser der Windungen allerhöchstens geringfügig überschreiten soll, bleibt quasi das größtmögliche polare Widerstandsmoment des Schraubenausdrehers erhalten.Essentially, there is only one pinch edge which is very flat. Because the depth of the crush edge the thread core diameter of the turns at most slightly should exceed the greatest possible polar moment of resistance of the screw extractor obtained.

Dabei kann es aber auch durchaus Sinn machen, die Kerbe nur bis auf den Grunddurchmesser der Windungen zu legen und insbesondere bei Schraubenausdrehen mit geringem Durchmesser, z.B. für Schrauben bis zu 8 mm, die Kerben nicht tiefer als etwa 2/3 der Zahnhöhe der Windungen auszuführen.But it can also make sense, the notch to lay only on the basic diameter of the turns and especially when unscrewing screws with a small diameter, e.g. for screws up to 8 mm, the notches no deeper than about 2/3 of the tooth height of the turns.

Im Hinblick auf die jeweils optimale Tiefe der Kerbe kann auch der Winkel zwischen der Quetschflanke und der Tangente an die Umfangskante der Quetschflanke so variiert werden, daß sich der größtmögliche Eingrabeffekt ohne Abschälwirkung auf die Axialbohrung ergibt.With regard to the optimal depth of the notch can also be the angle between the crushing flank and the tangent to be varied on the peripheral edge of the squeeze flank that the greatest possible burial effect without peeling effect on the axial bore.

Es soll daher eine ausgeprägte Spanbildung durch die Quetschflanke in jedem Fall vermieden werden. Dies ist die Voraussetzung für eine bevorzugt möglichst geringe Einkerbtiefe in der Einschraubzone und somit vorteilhaft für das größtmögliche übertragbare Drehmoment vom Schraubenausdreher auf den abgerissenen Schraubenstumpf.There should therefore be a pronounced chip formation through the Crushing flank should be avoided in any case. this is the Prerequisite for a preferably minimal notch depth in the screw-in zone and therefore advantageous for the maximum transferable torque from the screw extractor on the torn screw stump.

Für die Ausrichtung der Einkerbung bietet sich die Axialrichtung des Schraubenausdrehers an.For the alignment of the notch, the Axial direction of the screw extractor.

Eine gesteigerte Wirkung darf für eine Einkerbung erwartet werden, die praktisch senkrecht zu den Windungen der Einschraubzone steht.An increased effect may be expected for a notch be practically perpendicular to the turns of the Screw-in zone stands.

Eine zumindest paarweise symmetrische Anordnung derartiger Einkerbungen führt zu einem entsprechenden Spannungsaufbau im verbleibenden Restquerschnitt des Schraubenausdrehers. Zusätzlich läßt sich durch außermittig sekantialen Versatz der Quetschflanke deren Tendenz zur Spanabhebung zusätzlich unterbinden.An at least pairwise symmetrical arrangement of such Notches lead to a corresponding build-up of tension in the remaining cross-section of the screw extractor. In addition, secantials can be used off-center Offset of the crushing flank, their tendency to chip removal additionally prevention.

Bevorzugt soll die Quetschflanke entgegen der Einschraubrichtung des Schraubenausdrehers nach hinten oder in Einschraubrichtung außenmittig nach vorne versetzt werden. Dies führt zu verstärktem Eingrabeffekt und auch bei Quetschkanten, die an sich spanende Wirkung aufgrund ihrer Winkelgeometrie hätten, zum vorrangigen Eingrabeffekt. In jedem Falle soll also die Ausbildung von Spänen im Schraubenstumpf vermieden werden. Der außermittige Versatz nach vorne oder nach hinten soll jedoch allerhöchstens so groß sein, daß der Winkel zwischen der Quetschflanke und der Tangente an die Umfangskante der Quetschflanke nicht kleiner als 70 Grad und nicht größer 110 Grad trägt.The squeezing flank should preferably be counter to the screwing direction of the screw extractor backwards or in The screwing direction can be moved to the front in the center. This leads to an increased digging effect and also with crushed edges, the cutting effect due to its angular geometry would have to the primary burial effect. In each Trap should be the formation of chips in the screw stump be avoided. The off-center offset to the front or to the rear, however, should at most be so large that the Angle between the crushing flank and the tangent to the Circumferential edge of the crushing flank not less than 70 degrees and no greater than 110 degrees.

Diese Maßnahme läßt für übliche Werkzeugmaschinen genügend Spielraum, um auch bei groben Freimaßtoleranzen zu einem Werkzeug der vorliegenden Erfindung zu kommen.This measure leaves for common machine tools enough room to maneuver even with rough tolerances a tool of the present invention.

Derartige Quetschflanken können z.B. mit Scheibenfräsern hergestellt werden. Sie können über die gesamte Länge der Einschraubzone verlaufen oder lediglich lokal. Durch die Verwendung von Scheibenfräsern verlaufen die Einkerbungen an ihren axialen unteren und oberen Enden in die dort vorhandenen Windungen aus. Dennoch wird der gewünschte Effekt ohne weiteres erzielt. Da die lokale Anstauchung des Schraubenstumpfes infolge der auflaufenden Quetschkante im 1/10 mm Bereich liegt, ist es prinzipiell auch nicht erforderlich, die Einkerbung über die gesamte Länge der Einschraubzone verlaufen zu lassen.Such squeezing flanks can e.g. with side milling cutters getting produced. You can run the entire length of the Screw-in zone run or only locally. By using it the indentations run from disc milling cutters their axial lower and upper ends into those there Turns out. Nevertheless, the desired effect is without achieved further. Because the local upsetting of the screw stump due to the running crushing edge in the 1/10 mm range is, in principle, it is not necessary either Notch run over the entire length of the screw-in zone allow.

Durch Herstellung der Quetschflanke mit einem Scheibenfräser entstehen praktisch senkrecht aufeinander stehende Flanken. Hierdurch wird zusätzlich eine ausgeprägte Spanausbildung verhindert, weil der eventuell entstehende Span unter spitzem Winkel in die von beiden Flanken aufgespannte Ecke der Einkerbung läuft und dort gefangen wird. Der gewünschte Staucheffekt wird somit begünstigt.By producing the crushing flank with a side milling cutter arise practically perpendicular to each other Flanks. This also creates a pronounced chip formation prevented because of the possibly arising chip under acute angle in the corner spanned by both flanks the notch runs and is caught there. The one you want The compression effect is thus favored.

Im folgenden wird die Erfindung anhand von Ausführungsbeispielen näher erläuert. Es zeigen:

Fig.1
ein erstes Ausführungsbeispiel der Erfindung,
Fig.2
die Wirkungsweise der Erfindung bei einem Ausführungsbeispiel gemäß Fig.1,
Fig.3
ein weiteres Ausführungsbeispiel der Erfindung,
Fig.4
das Ausführungsbeispiel gemäß Fig.3 entlang der Blickrichtung IV.
The invention is explained in more detail below on the basis of exemplary embodiments. Show it:
Fig.1
a first embodiment of the invention,
Fig.2
the operation of the invention in an embodiment according to Figure 1,
Figure 3
another embodiment of the invention,
Figure 4
the embodiment of Figure 3 along the viewing direction IV.

Sofern im folgenden nichts anderes gesagt ist, gilt die folgende Beschreibung stets für alle Figuren.Unless otherwise stated below, the following description always for all figures.

Die Figuren zeigen einen Schraubenausdreher 1 zum Ausdrehen von Schraubenstümpfen 10 abgerissener Schrauben.The figures show a screw extractor 1 for unscrewing of screw stumps 10 torn screws.

Der Schraubenausdreher 1 weist an seinem oberen Ende einen Antriebsschaft 2 auf, der zum Aufsetzen eines Windeisens dient. Derartige Schraubenausdreher werden stets nur manuell eingesetzt.The screw extractor 1 has at its upper end a drive shaft 2, which is used to put on a tap wrench serves. Such screw extractors are always only manually inserted.

Der Antriebsschaft 2 setzt sich nach vorne fort in einen länglich-zylindrischen Übergangsbereich 3. Im Übergangsbereich 3 ist keinerlei Gewinde vorgesehen. Der Übergangsbereich 3 verläuft geradzylindrisch.The drive shaft 2 continues forward into one oblong-cylindrical transition area 3. In the transition area 3 no thread is provided. The transition area 3 is straight cylindrical.

Daran befindet sich eine Einschraubzone 4 mit einzelnen Windungen 7, die sich bis zur Spitze 5 des Schraubenausdrehers 1 erstrecken. Es können z.B. drei Parallelwindungen vorgesehen sein, um bei einer entsprechend großen Gewindesteigung dennoch ausreichend dicht benachbarte Windungen zu erhalten. Bevorzugt werden Windungen, die sich im Fußbereich praktisch unmittelbar berühren.There is a screw-in zone 4 with individual Windings 7, which extend to the tip 5 of the screw extractor 1 extend. For example three parallel turns are provided to be at a correspondingly large thread pitch to get sufficiently close turns. Preference is given to turns that are in the foot area touch almost immediately.

Die gesamte Einschraubzone 4 verläuft kegelartig unter dem Kegelwinkel 6 zur Spitze 5 hin verjüngt. Mit dieser Kegelspitze wird derartiger Schraubenausdreher 1 in die axiale Bohrung 11 des abgerissenen Schraubenstumpfs 10 hineingedreht. Da die Richtung 8 der Windung 7 entgegengesetzt zur Gewinderichtung 9 des abgerissenen Schraubenstumpfs 10 verläuft, kann auf diese Weise der abgerissene Schraubenstumpf 10 mit einigem Geschick aus seiner Gewindebohrung herausgedreht werden. The entire screw zone 4 runs like a cone the cone angle 6 tapers towards the tip 5. With this cone tip is such a screw extractor 1 in the axial Drilled hole 11 of the torn screw stub 10. Since the direction 8 of the winding 7 opposite to Thread direction 9 of the torn screw stub 10 runs, can the broken screw stump 10 screwed out of its threaded hole with some skill become.

Dies setzt jedoch voraus, daß zwischen dem Schraubenausdreher 1 und dem Schraubenstumpf 10 eine starre Drehverbindung entsteht, daß sich der Schraubenausdreher 1 sozusagen im Schraubenstumpf 10 in Umfangsrichtung festsetzt.However, this presupposes that between the screw extractor 1 and the screw stump 10 a rigid rotary connection arises that the screw extractor 1, so to speak Screw stub 10 sets in the circumferential direction.

Insofern ist ein derartiger Schraubenausdreher stets ein mechanischer Kompromiß sich widersprechender Anforderungen.In this respect, such a screw extractor is always a mechanical compromise of conflicting requirements.

Einerseits soll nämlich die Aufspreizung des Schraubenstumpfs 10 nur sehr gering bleiben. Damit soll eine Anpressung des Schraubenstumpfs 10 in seiner Gewindebohrung verhindert werden. Dies läßt sich jedoch nur mit Axialbohrungen 11 geringer Durchmesser erzielen. Dann jedoch besteht die erhebliche Gefahr, daß ein derartiger Schraubenausdreher trotz Fingerspitzengefühls bei der Anwendung abreißt.On the one hand, namely, the expansion of the screw stump 10 remain very low. This is supposed to be a contact pressure of the screw stump 10 prevented in its threaded bore become. However, this can only be done with axial bores 11 achieve a small diameter. Then, however, there is considerable Danger of such a screw extractor despite Sensitivity tears off when using.

Dem kann man zwar durch große Einschraubtiefen des Schraubenausdrehers in den Schraubenstumpf begegnen. Dies setzt jedoch entsprechend geringe Wandstärken im Schraubenstumpf voraus, wodurch die Gefahr der Aufspreizung und damit der Festsetzung des Schraubenstumpfs steigt.You can do this by screwing the Encounter screw extractor in the screw stump. This however, sets correspondingly small wall thicknesses in the screw stump ahead, increasing the risk of spreading and hence the fixation of the screw stump increases.

Um dennoch hier zu einer gezielten Erhöhung des Antriebsmoments im Drehverbundstück zu kommen, sind in der Einschraubzone 4 Maßnahmen zur Erhöhung des eingeleiteten Drehmoments vorgesehen.In order to increase the drive torque to come in the swivel joint are in the screw-in zone 4 measures to increase the initiated torque intended.

Diese Maßnahmen sehen in der Einschraubzone 4 eine flache und höchstens nur geringfügig tiefer als bis auf den Grunddurchmesser 19 der Windungen 7 gehende Einkerbung 12 vor, welche die Windungen 7 lediglich anschneidet. Die Einkerbung 12 verläuft quer über mehrere Windungen 7 und weist in der Ausdrehrichtung des Drehverbundstücks, bestehend aus Schraubenausdreher 1 und Schraubenstumpf 10, eine in der Axialbohrung 11 des Schraubenstumpfs 10 auflaufende Quetschflanke 14 auf. Die Ausdrehrichtung des Drehverbundstücks 1 + 10 fällt mit der Eindrehrichtung der Einschraubzone 4 zusammen. Wie Fig.2 im Detail zeigt, besitzt die Einkerbung 12 eine auflaufende Flanke 15, mit welcher sich die Einkerbung 12 in das Material des Schraubenstumpfs 10 einarbeitet sowie eine ablaufende Flanke 16, die bei der Eindrehrichtung des Schraubenausdrehers 1 diesen Effekt vorbereitet.These measures see in the screw-in zone 4 flat and at most only slightly deeper than except for the Basic diameter 19 of the turns 7 indentation 12 before, which only cuts the windings 7. The notch 12 runs across several turns 7 and points in the direction of rotation of the rotating composite, consisting of Screw extractor 1 and screw stub 10, one in the Axial bore 11 of the screw stump 10 rising crushing flank 14 on. The direction of rotation of the rotating joint 1 + 10 coincides with the screwing-in direction of the screw-in zone 4. As FIG. 2 shows in detail, the notch 12 has a leading edge 15 with which the notch 12 incorporated into the material of the screw stump 10 and a trailing edge 16, which is in the direction of rotation of the Screw extractor 1 prepared this effect.

Die auflaufende Flanke 15 bestimmt folglich die Tiefe 13, mit welcher die Einkerbung 12 in das Material des Schraubenausdrehers eingebracht ist. Diese Einbringtiefe 13 soll praktisch nicht tiefer als die Gewindehöhe 17 sein, also die halbe Differenz zwischen dem Außendurchmesser 18 des Schraubenausdrehers und dem Grunddurchmesser 19.The rising edge 15 consequently determines the depth 13, with which the notch 12 in the material of the screw extractor is introduced. This insertion depth 13 should practically no deeper than the thread height 17, that is half the difference between the outer diameter 18 of the screw extractor and the basic diameter 19.

Da sich der Schraubenausdreher bei richtiger Anwendung unter quetschender Verdrängung des Randmaterials der Axialbohrung 11 in den Schraubenstumpf 10 einarbeitet, gerät ab einer bestimmten Einschraubtiefe die auflaufende Flanke 15, welche hier als Quetschflanke bezeichnet wird, mit zunehmend größer werdender Eingriffszone in die Wandung des Schraubenstumpfes 11 und schiebt das Material des Schraubenstumpfs so lange vor sich her, bis der Schraubenausdreher 1 in Umfangsrichtung drehstarr verbunden ist. Diese entscheidende Phase des Ausdrehvorgangs bestimmt letztlich den Erfolg. Solange das Losbrechmoment des Schraubenstumpfs 10 noch nicht überschritten ist, muß der Schraubenausdreher 1 weiter in das Material des Schraubenstumpfs eingezogen werden.Since the screw extractor is used correctly while squeezing the edge material of the axial bore 11 worked into the screw stump 10, from the rising flank 15 of a certain screw-in depth, which is referred to here as the squeeze flank, with increasing increasing engagement zone in the wall of the screw stump 11 and pushes the material of the screw stump like this a long time before the screw extractor 1 in the circumferential direction is rigidly connected. This crucial phase the unscrewing process ultimately determines success. As long as the breakaway torque of the screw stump 10 has not yet been exceeded is, the screw extractor 1 must continue in the Material of the screw stump.

Darüber hinaus zeigen die Figuren Ausführungsbeispiele, bei denen die Tiefe 13 der Einkerbung 12 nicht mehr als das Doppelte der Gewindehöhe 17 ist.In addition, the figures show exemplary embodiments, where the depth 13 of the notch 12 is no more than that Double the thread height is 17.

Bevorzugt wird allerdings eine Ausführungsform, bei welcher der Grunddurchmesser 19 der Windungen 7 höchstens gerade eben angeschnitten wird. Für Schraubenausdreher geringer Durchmesser wird jeglicher Anschnitt vorteilhaft jedoch sogar vermieden. Dann liegt die Tiefe 13 der Einkerbung 12 innerhalb der Gewindehöhe 17, um eine höhere Torsionsfestigkeit des Schraubenausdrehers 1 zu erzielen.However, an embodiment is preferred in which is the basic diameter 19 of the windings 7 at most straight is just being cut. Less for screw extractors Any chamfer will even be advantageous in diameter avoided. Then the depth 13 of the notch 12 is within the thread height 17 for a higher torsional strength of the screw extractor 1.

Darüber hinaus zeigt Fig.2 ein Ausführungsbeispiel, bei welchem die Längsrichtung der Einkerbung 12 mit der Axialrichtung des Schraubenausdrehers zusammenfällt. In addition, Figure 2 shows an embodiment, at which is the longitudinal direction of the notch 12 with the axial direction of the screw extractor coincides.

Abweichend hiervon zeigt Fig.3 ein Ausführungsbeispiel, bei welchem die Einkerbung 12 praktisch senkrecht zu der Richtung der Windungen 7 steht.3 shows an exemplary embodiment, in which the notch 12 is practically perpendicular to the Direction of the turns 7 is.

Um einen symmetrischen Eingriff des Schraubenausdrehers 1 im Schraubenstumpf 10 zu erzielen, können sich jeweils zwei Einkerbungen 12 paarweise gegenüberliegen.For a symmetrical engagement of the screw extractor To achieve 1 in the screw stump 10, there can be two Notches 12 face each other in pairs.

Ferner zeigen die Figuren den Sonderfall, daß die Quetschflanke 14 um ein Wegstück außermittig versetzt (20) ist. Dies bedeutet, daß die auflaufende Flanke 15 nicht an ihrem größtmöglichen Hebelarm an der Axialbohrung 11 angreift. Es erfolgt daher auch ein gewisser zusätzlicher Verquetschungseffekt, da der an sich unerwünschte Schneideffekt der auflaufenden Flanke 15 zusätzlich unterbunden wird.Furthermore, the figures show the special case that the Crimp edge 14 offset off-center by a distance (20) is. This means that the rising edge 15 is not on their largest possible lever arm engages the axial bore 11. There is therefore also a certain additional squeezing effect, because the undesirable cutting effect the rising edge 15 is additionally prevented.

Der außermittige Versatz 20 kann auch im Millimeterbereich liegen.The off-center offset 20 can also be in the millimeter range lie.

Stellt man die Einkerbung 12 mit einem Scheibenfräser her, weist sie lediglich zwei Flanken auf, die zueinander unter einem Winkel von praktisch 90 Grad stehen.Make the notch 12 with a side milling cutter forth, it only has two flanks that face each other stand at an angle of practically 90 degrees.

Derartige Einkerbungen 12 erfüllen den Zweck der Erfindung voll und ganz.Such notches 12 serve the purpose of the invention fully.

Durch werkzeugbedingten Verschleiß kann aber auch die Quetschflanke 15 unter einem geringfügigen Radius von bis zu etwa 2 mm hin in die ablaufende Flanke 16 übergehen.Due to tool-related wear, however, this can also occur Crimp edge 15 with a small radius of up to pass about 2 mm into the trailing flank 16.

Darüber hinaus zeigt Fig. 3 ein Ausführungsbeispiel, bei welchem die Quetschflanke 14 Bestandteil eines kreisabschnittförmigen Anschnittes ist, wie er leicht durch Verwendung eines Scheibenfräsers bei derartigen Schraubenausdrehern 1 herstellbar ist.In addition, Fig. 3 shows an embodiment, at which the squeeze edge 14 is part of a circular segment Bleed is how easy it is by use a side milling cutter in such screw extractors 1 can be produced.

Es können mehrere derartige Ausnehmungen auf dem Umfang der Einschraubzone 4 in Längsrichtung verteilt werden. There can be several such recesses on the circumference the screw-in zone 4 are distributed in the longitudinal direction.

Bei der in Fig.3 gezeigten Ausführungsform läuft zusätzlich die Quetschflanke 14 genau unter 90 Grad zu der Richtung der Windung 7. Hierdurch wird der angestrebte Staucheffekt zusätzlich verbessert.In the embodiment shown in Figure 3 runs additionally the crush edge 14 is exactly 90 degrees to the direction the turn 7. This will achieve the desired compression effect additionally improved.

Darüber hinaus zeigt Fig.2 ergänzende Maßnahmen zur Verhinderung eines Schneideffekts, der durch die Quetschflanke 14 genau nicht erzielt werden soll. Zu diesem Zwecke schließt die Quetschflanke 14 mit der Tangente 21 an ihrer Umfangskante einen Winkel 22 ein, der hier 90 Grad beträgt.Fig. 2 also shows additional measures for prevention a cutting effect caused by the crushing edge 14 should not be achieved exactly. For this purpose it closes the squeeze flank 14 with the tangent 21 on its peripheral edge an angle 22, which is 90 degrees here.

Abweichungen von +- 20 Grad sind jedoch nicht schädlich im Sinne der Erfindung.However, deviations of + - 20 degrees are not harmful in the sense of the invention.

Maßgeblich allein ist das Ausnutzen der Verformung des Materials des Schraubenstumpfes durch den Eingrabeffekt, den die Quetschkante 14 hervorruft. The only decisive factor is the use of the deformation of the Material of the screw stump due to the burr effect the pinch edge 14 causes.

Bezugszeichenliste:LIST OF REFERENCE NUMBERS

11
SchraubenausdreherScrew
22
Antriebsschaftdrive shaft
33
länglich zylindrischer Übergangsbereichelongated cylindrical transition area
44
EinschraubzoneEinschraubzone
55
Spitzetop
66
Kegelwinkelcone angle
77
Windungenturns
88th
Windungsrichtungcoiling
99
Gewinderichtungthread direction
1010
Schraubenstumpfscrew stump
1111
axiale Bohrungaxial bore
1212
Einkerbungnotch
1313
Tiefe der EinkerbungNotch depth
1414
QuetschflankeQuetschflanke
1515
auflaufende Flankeleading edge
1616
ablaufende Flanketrailing edge
1717
Gewindehöhethread height
1818
Außendurchmesserouter diameter
1919
GrunddurchmesserBase diameter
2020
außermittiger Versatzoff-center offset
2121
Tangente an UmfangskanteTangent to the peripheral edge
2222
eingeschlossener Winkelincluded angle

Claims (6)

  1. Screw extractor (1) for screwing out screw stumps (10) of broken-off screws, wherein the screw extractor (1) comprises a screw-in zone (4) which tapers conically (6) towards the tip (5) and which comprises a plurality of windings (7) which are mutually closely adjacent and extend in parallel with each other, which windings run in the opposite direction to the direction (9) of the threads of the screw stump (19) to be screwed out and by means of which windings the screw extractor (1) is drawn into an axial bore (11) in the screw stump to such a depth that together with the screw stump (10) it forms a combination piece (1 + 10) which will turn, wherein in the screw-in zone (4) at least one notch is provided which extends transversely across several windings in order to increase the torque introduced into the screw stump (10), which notch comprises only two flanks which are practically perpendicular to each other and of which the one flank is aligned as an upward running flank (15) and the other as a downward running flank (6), characterised in that,
    the upward running flank (15) is formed as a pinched flank (14) which is formed from a plurality of mutually closely adjacent nick surfaces comprising the triangular cross-sections of a multi-thread angular screw thread, and that
    the notch intersects the windings (7) offset from the centre by a distance piece of such a maximum size that the angle (22) between the pinched flank (14) and the tangent (21) to the peripheral edge of the pinched flank (14) amounts to 90° plus/minus 20°.
  2. Screw extractor as claimed in Claim 1, characterised in that the pinched flank (14) changes into the downward running flank (16) with a radius of less than 2mm.
  3. Screw extractor as claimed in Claim 1 or 2, characterised in that the notch (12) coincides with the axial direction of the screw extractor (1).
  4. Screw extractor as claimed in Claim 1 or 2, characterised in that the pinched flank (14) is formed as a circle segment-shaped nick.
  5. Screw extractor as claimed in any one of Claims 1 to 4, characterised in that the notch (12) is practically perpendicular to the windings (6).
  6. Screw extractor according to any one of C laims 1 to 5, characterised in that in each case two notches (12) lie in pairs opposite each other.
EP99104364A 1998-03-05 1999-03-04 Screw extractor Expired - Lifetime EP0940228B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19809252 1998-03-05
DE19809252A DE19809252C2 (en) 1998-03-05 1998-03-05 Screw extractor

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Publication Number Publication Date
EP0940228A2 EP0940228A2 (en) 1999-09-08
EP0940228A3 EP0940228A3 (en) 2003-01-15
EP0940228B1 true EP0940228B1 (en) 2004-02-18

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AT (1) ATE259692T1 (en)
DE (2) DE19809252C2 (en)

Cited By (1)

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Publication number Priority date Publication date Assignee Title
TWI746632B (en) * 2016-09-09 2021-11-21 比利時商赫比工具公司 Process for extracting safety screw for motor vehicle wheels, extractor and set of tools for executing the process and use of the extractor and set of tools

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6761089B2 (en) * 2002-07-01 2004-07-13 Proqual, Llc Tool for removing screws with damaged heads
DE102013101293A1 (en) * 2013-02-08 2014-08-28 Lin Fu-Hua Release tool e.g. wrench for detaching a damaged-fastening element e.g. screw, has several helical teeth that are formed in radial surface of toothed ribs, and extended in tilt direction with respect to central axis in length direction

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US1754736A (en) * 1929-12-28 1930-04-15 Greenfield Tap & Die Corp Screw extractor
DE625735C (en) * 1930-12-19 1936-02-14 Greenfield Tap And Die Corp Tool for removing broken screws
US1863046A (en) * 1931-07-11 1932-06-14 Cleveland Twist Drill Co Extractor
US2480648A (en) * 1947-11-03 1949-08-30 Delmar C Harer Stud extractor and method of making the same
US3263533A (en) * 1964-08-27 1966-08-02 Textron Ind Inc Screw extractor
DE4334471A1 (en) * 1993-10-10 1995-04-13 Michael Dipl Ing Fuessel Screw extractor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI746632B (en) * 2016-09-09 2021-11-21 比利時商赫比工具公司 Process for extracting safety screw for motor vehicle wheels, extractor and set of tools for executing the process and use of the extractor and set of tools

Also Published As

Publication number Publication date
DE19809252A1 (en) 1999-09-16
EP0940228A2 (en) 1999-09-08
EP0940228A3 (en) 2003-01-15
DE59908542D1 (en) 2004-03-25
ATE259692T1 (en) 2004-03-15
DE19809252C2 (en) 2000-04-06

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