EP0406247B1 - Eccentric grinding machine - Google Patents

Eccentric grinding machine Download PDF

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Publication number
EP0406247B1
EP0406247B1 EP89901938A EP89901938A EP0406247B1 EP 0406247 B1 EP0406247 B1 EP 0406247B1 EP 89901938 A EP89901938 A EP 89901938A EP 89901938 A EP89901938 A EP 89901938A EP 0406247 B1 EP0406247 B1 EP 0406247B1
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EP
European Patent Office
Prior art keywords
eccentric
backing pad
intermediate disc
toothed
disc
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.)
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EP89901938A
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German (de)
French (fr)
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EP0406247A1 (en
Inventor
Günter Schaal
Fred Weinmann
Günther Berger
Dieter Dörr
Karl-Heinz Braunbach
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B23/00Portable grinding machines, e.g. hand-guided; Accessories therefor
    • B24B23/02Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor
    • B24B23/03Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor the tool being driven in a combined movement
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B55/00Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition
    • B24B55/06Dust extraction equipment on grinding or polishing machines
    • B24B55/10Dust extraction equipment on grinding or polishing machines specially designed for portable grinding machines, e.g. hand-guided
    • B24B55/102Dust extraction equipment on grinding or polishing machines specially designed for portable grinding machines, e.g. hand-guided with rotating tools

Definitions

  • the invention is based on an eccentric grinder according to the preamble of the main claim.
  • An eccentric grinder known from EP-A 254 850 has a central hub body which supports the grinding plate and has a friction surface which counteracts a turning up of the grinding plate as a result of bearing friction when idling. Furthermore, the hub body can be coupled with axially displaceable toothing, which is connected to the housing in a rotationally fixed manner. The entire gearbox structure is complicated and, with a large overall length, requires considerable effort for balancing.
  • the eccentric grinder according to the invention with the characterizing features of claim 1 has the advantage that it allows two or more differently rough grinding movements with a simple gear structure. In addition, the flatter design of the eccentric grinding head makes handling much easier.
  • the washers according to claim 5 reach up to the eccentric shaft and have a heat-conducting connection therewith.
  • the heat generated in the bearings of the eccentric shaft can be dissipated into the washer and released by the latter to the ventilation flow passing through the ventilation openings.
  • the ventilation openings also make it easier to remove the washer by hand.
  • the arrangement of the ventilation openings on the sanding plate according to claim 10 enables the use of both the commercially available six-hole sanding papers and those with eight holes.
  • FIG. 1 shows a cross section through the eccentric grinder
  • FIG. 2 shows a perspective view of the fan wheel and one of the Intermediate discs
  • Figure 3 shows the arrangement of the ventilation openings on the grinding plate.
  • An eccentric grinder 1 has a motor housing 2 and a grip shell 3, which is arranged above a gear housing 4 for an angular gear with an output shaft 5.
  • a fan housing 6 is attached, which has an exhaust port 7.
  • a fan wheel 8 which is firmly connected to the output shaft 5.
  • An eccentric shaft 9 with the eccentricity X to the axis of the drive shaft 4 is inserted in the fan wheel 8 from below and is supported by means of the bearings 10 and 11.
  • the eccentric shaft 9 has a collar 12 and a square end section 13 with an internal thread for a fastening screw 14.
  • the intermediate disk 17 with a square central opening 18 is slipped onto the end section 12.
  • the intermediate disc 17 is preferably made of aluminum, which is provided with a hard, wear-resistant surface by anodizing.
  • the intermediate disc 17 has a raised ring 19 on both sides, which lies against the collar 12 of the eccentric shaft 9 for centering. Radially outside the ring 19, the washer 17 has ventilation openings 20.
  • the intermediate disk 17 carries on each side a friction or toothed ring 21, 22 of preferably different diameters.
  • the ring gears 21, 22 can be made of aluminum, the base material of the intermediate disk 17, or of plastic. With its raised central region 23, a grinding plate 24 bears against the intermediate disk 17. It is also attached to the end section 13 with a central square opening 25.
  • the grinding plate 24 carries a projecting collar 26 pointing toward the intermediate disc 17.
  • An elastic pad 27 is placed on the grinding plate 24.
  • the grinding plate 24 and the pad 27 have ventilation openings 28, 29.
  • the ventilation openings 20 and 28 and 29 are arranged so that they lie congruently one above the other when the intermediate disc 17 and the grinding plate 24 are attached to the square trim 13.
  • An abrasive paper 30 is fastened to the support 27, for example by means of a Velcro fastener.
  • a toothed disc 31 is fastened to the fixed fan housing 6 by means of three screws 32. To prevent rotation and for centering, the toothed disk 31 has pins 33 which engage in corresponding recesses in the fan housing 5. Instead of using screws 32, the toothed disk can also be fastened to the fan housing 6 by means of snap locks.
  • the toothed disk 31 On the side facing the intermediate disk 17, the toothed disk 31 carries two friction or toothed rings 34, 35 of different diameters, which can be brought into engagement with the toothed rings 21, 22 on the intermediate disk 17.
  • the sprockets 34, 35 are either made of plastic or in a wear-resistant metal, so that each with the sprockets 21, 22 results in a pair of metal and plastic, in which wear can only occur on the easily replaceable plastic teeth.
  • FIG. 2 shows a second intermediate disk 37 which has rings 38, 39 on the circumference which correspond to the toothed rings 34, 35 on the intermediate disk 17, but are toothless.
  • the intermediate disk 37 like the intermediate disk 17, has a raised ring 40 on both sides and a central square opening 41.
  • the ventilation openings 42 correspond to the openings 20.
  • the intermediate disk 37 On one of its two sides, the intermediate disk 37 carries webs 43 which extend radially outward from the ring 40 and which can be inserted in a form-fitting manner in recesses 44 on the fan wheel 8. This creates a rotationally fixed connection between the fan wheel 8 and the intermediate disk 37.
  • the webs 43 are missing on the rear side, not shown, so that the intermediate disk 37, when it faces the fan wheel 8 with the rear side, can rotate freely without contact with it, as is also the case with the intermediate disk 17 (see FIG. 1).
  • the arrangement of the ventilation openings 28 in the grinding plate 24 is shown in FIG. Six of the openings are arranged in a circular symmetry on a diameter 46 of approximately 80 mm and approximately eight openings 47 on a diameter of approximately 65 mm.
  • the fan wheel 8 fulfills several functions. In addition to generating the eccentric movement and compensating for unbalance, it generates a suction air flow that also serves to cool the bearings and the gears. Grinding dust-laden air is sucked in through the ventilation openings 29 and 28 in the grinding plate and 20 in the intermediate disc and released again via the exhaust air connector 7. At the same time, the intermediate disk 17 or 37 is cooled by the ventilation flow, to which the heat generated in the bearings 10 and 11 is released via the eccentric shaft 12.
  • the invention is not limited to the exemplary embodiment shown. Instead of the two reversible intermediate discs 17 and 37, four individual discs can also be used, each of which can be firmly connected to its own grinding plate in the central area. This would also result in a flatter design for the grinder.
  • the four grinding movements can also be generated by means of a single washer, which carries the two differently sized sprockets on the same side and whose webs that can be inserted into the fan wheel are detachable, foldable or switchable from the outside during the fine, medium-sized and rough grinding movement.
  • they would be non-rotatably connected to the housing Sprockets axially displaceable so that either one, the other or neither of the two come into engagement with the sprockets of the washer.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Abstract

The eccentric drive of an eccentric grinding machine is designed to eliminate the undesirable effects due to operation of the grinding disc and to improve the cooling. To permit decoupling of the eccentric drive from the grinding disk (24), only the central region of the latter is connected to the intermediate disk (17), which is provided with a gear rim (21, 22). At the same time, the intermediate disk (17) conducts the heat generated in the bearings (10, 11) to the suction air stream flowing through the ventilation ports (28, 29). The eccentric grinding wheel executes four different fine grinding movements and is therefore suitable for all grinding operations.

Description

Die Erfindung geht aus von einem Exzenterschleifer nach der Gattung des Hauptanspruchs. Ein aus der EP-A 254 850 bekannter Exzenterschleifer weist einen den Schleifteller tragenden zentralen Nabenkörper mit einer Reibfläche auf, die im Leerlauf einem Hochdrehen des Schleiftellers infolge Lagerreibung entgegenwirkt. Weiterhin ist der Nabenkörper mit einer axialverschieblichen Verzahnung kuppelbar, die drehfest mit dem Gehäuse verbunden ist. Der gesamte Getriebeaufbau ist kompliziert und erfordert bei großer Baulänge einen erheblichen Aufwand zum Unwuchtausgleich.The invention is based on an eccentric grinder according to the preamble of the main claim. An eccentric grinder known from EP-A 254 850 has a central hub body which supports the grinding plate and has a friction surface which counteracts a turning up of the grinding plate as a result of bearing friction when idling. Furthermore, the hub body can be coupled with axially displaceable toothing, which is connected to the housing in a rotationally fixed manner. The entire gearbox structure is complicated and, with a large overall length, requires considerable effort for balancing.

Vorteile der ErfindungAdvantages of the invention

Der erfindungsgemäße Exzenterschleifer mit den kennzeichnenden Merkmalen des Anspruchs 1 hat demgegenüber den Vorteil, daß er bei einfachem Getriebeaufbau zwei oder mehr unterschiedlich grobe Schleifbewegungen zuläßt. Hinzu kommt eine erhebliche Handhabungserleichterung durch die flachere Bauweise des Exzenterschleifkopfes.The eccentric grinder according to the invention with the characterizing features of claim 1 has the advantage that it allows two or more differently rough grinding movements with a simple gear structure. In addition, the flatter design of the eccentric grinding head makes handling much easier.

Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen des im Hauptanspruch angegebenen Exzenterschleifers möglich. Besonders vorteilhaft ist, daß die Zwischenscheiben gemäß Anspruch 5 bis an die Exzenterwelle heranreichen und eine wärmeleitende Verbindung damit haben. Dadurch kann die in den Lagern der Exzenterwelle entstehende Wärme in die Zwischenscheibe abgeleitet und von diesen an den durch die Lüftungsdurchbrüche tretenden Lüftungsstrom abgegeben werden. Die Lüftungsdurchbrüche erleichtern außerdem das Herausnehmen der Zwischenscheibe mit der Hand.Advantageous further developments and improvements of the eccentric grinder specified in the main claim are possible through the measures listed in the subclaims. It is particularly advantageous that the washers according to claim 5 reach up to the eccentric shaft and have a heat-conducting connection therewith. As a result, the heat generated in the bearings of the eccentric shaft can be dissipated into the washer and released by the latter to the ventilation flow passing through the ventilation openings. The ventilation openings also make it easier to remove the washer by hand.

Vorteilhaft ist auch die Verwendung von vier unterschiedlich ausgebildeten Zwischenscheiben bzw. von zwei Zwischenscheiben mit zwei verschiedenen Seiten nach den Ansprüchen 6 und 7. Dies ermöglicht insgesamt vier unterschiedlich feine Schleifbewegungen des Exzenterschleifers.It is also advantageous to use four differently designed intermediate discs or two intermediate discs with two different sides according to claims 6 and 7. This enables a total of four differently fine grinding movements of the eccentric grinder.

Durch die Ausführung der mit dem Gehäuse verbundenen Zahnkränze in Kunststoff und der Zahnkränze der Zwischenscheibe in verschleißfestem Metall oder umgekehrt treten Abnutzungserscheinungen bestenfalls einseitig an der Kunststoffverzahnung auf, die leicht auswechselbar ist.Due to the design of the sprockets connected to the housing in plastic and the sprockets of the washer in wear-resistant metal or vice versa, signs of wear occur at best on one side of the plastic toothing, which is easy to replace.

Die Anordnung der Lüftungsdurchbrüche am Schleifteller nach Anspruch 10 ermöglicht die Verwendung sowohl der handelsüblichen Sechslochschleifpapiere als auch solcher mit acht Löchern.The arrangement of the ventilation openings on the sanding plate according to claim 10 enables the use of both the commercially available six-hole sanding papers and those with eight holes.

Zeichnungdrawing

Ein Ausführungsbeispiel des Erfindungsgegenstandes ist in der Zeichnunmg dargestellt und in der nachfolgenden Beschreibung erläutert. Es zeigen Figur 1 einen Querschnitt durch den Exzenterschleifer, Figur 2 eine perspektivische Ansicht des Lüfterrades und einer der Zwischenscheiben und Figur 3 die Anordnung der Lüftungsdurchbrüche auf dem Schleifteller.An embodiment of the subject of the invention is shown in the drawing and explained in the following description. FIG. 1 shows a cross section through the eccentric grinder, FIG. 2 shows a perspective view of the fan wheel and one of the Intermediate discs and Figure 3 shows the arrangement of the ventilation openings on the grinding plate.

Beschreibung des AusführungsbeispielsDescription of the embodiment

Ein Exzenterschleifer 1 hat ein Motorgehäuse 2 und eine Griffschale 3, die über einem Getriebegehäuse 4 für ein Winkelgetriebe mit Abtriebswelle 5 angeordnet ist. An dem Gehäuse 4 ist ein Lüftergehäuse 6 befestigt, das einen Abluftstutzen 7 aufweist. In dem Lüftergehäuse 6 befindet sich ein Lüfterrad 8, das mit der Abtriebswelle 5 fest verbunden ist. In dem Lüfterrad 8 ist von unten eine Exzenterwelle 9 mit der Exzentrizität X zur Achse der Antriebswelle 4 eingesetzt und mittels der Lager 10 und 11 gelagert. Die Exzenterwelle 9 weist einen Bund 12 und einen vierkantigen Endabschnitt 13 mit einem Innengewinde für eine Befestigungsschraübe 14 auf.An eccentric grinder 1 has a motor housing 2 and a grip shell 3, which is arranged above a gear housing 4 for an angular gear with an output shaft 5. On the housing 4, a fan housing 6 is attached, which has an exhaust port 7. In the fan housing 6 there is a fan wheel 8 which is firmly connected to the output shaft 5. An eccentric shaft 9 with the eccentricity X to the axis of the drive shaft 4 is inserted in the fan wheel 8 from below and is supported by means of the bearings 10 and 11. The eccentric shaft 9 has a collar 12 and a square end section 13 with an internal thread for a fastening screw 14.

Auf den Endabschnitt 12 ist eine Zwischenscheibe 17 mit einer vierkantigen mittigen Durchbrechung 18 aufgesteckt. Die Zwischenscheibe 17 ist vorzugsweies aus Aluminium, das durch Anodisieren mit einer harten, verschleißfesten Oberfläche versehen ist. Die Zwischenscheibe 17 hat beidseitig je einen erhabenen Ring 19, der zur Zentrierung an dem Bund 12 der Exzenterwelle 9 anliegt. Radial außerhalb des Rings 19 weist die Zwischenscheibe 17 Lüftungsdurchbrüche 20 auf. Am Außenrand trägt die Zwischenscheibe 17 auf jeder Seite je einen Reib- oder Zahnkranz 21, 22 von vorzugsweise unterschiedlichen Durchmessern. Die Zahnkränze 21, 22 können in Aluminium, dem Grundwerkstoff der Zwischenscheibe 17, oder in Kunststoff ausgeführt sein. Mit seinem erhöhten Mittelbereich 23 liegt ein Schleifteller 24 an der Zwischenscheibe 17 an. Er ist ebenfalls auf den Endabschnitt 13 mit einer mittigen vierkantigen Durchbrechung 25 aufgesteckt. Der Schleifteller 24 trägt einen zur Zwischenscheibe 17 hinweisenden hervorstehenden Bund 26. Auf den Schleifteller 24 ist eine elastische Auflage 27 aufgesetzt. Der Schleifteller 24 und die Auflage 27 weisen Lüftungsdurchbrüche 28, 29 auf. Die Lüftungsdurchbrüche 20 sowie 28 und 29 sind so angeordnet, daß sie deckungsgleich übereinanderliegen, wenn die Zwischenscheibe 17 und der Schleifteller 24 auf den vierkantigen beschnitt 13 aufgesteckt sind. An der Auflage 27 ist ein Schleifpapier 30 z.B. mittels Klettverschluß befestigt.An intermediate disk 17 with a square central opening 18 is slipped onto the end section 12. The intermediate disc 17 is preferably made of aluminum, which is provided with a hard, wear-resistant surface by anodizing. The intermediate disc 17 has a raised ring 19 on both sides, which lies against the collar 12 of the eccentric shaft 9 for centering. Radially outside the ring 19, the washer 17 has ventilation openings 20. On the outer edge, the intermediate disk 17 carries on each side a friction or toothed ring 21, 22 of preferably different diameters. The ring gears 21, 22 can be made of aluminum, the base material of the intermediate disk 17, or of plastic. With its raised central region 23, a grinding plate 24 bears against the intermediate disk 17. It is also attached to the end section 13 with a central square opening 25. The grinding plate 24 carries a projecting collar 26 pointing toward the intermediate disc 17. An elastic pad 27 is placed on the grinding plate 24. The grinding plate 24 and the pad 27 have ventilation openings 28, 29. The ventilation openings 20 and 28 and 29 are arranged so that they lie congruently one above the other when the intermediate disc 17 and the grinding plate 24 are attached to the square trim 13. An abrasive paper 30 is fastened to the support 27, for example by means of a Velcro fastener.

An dem feststehenden Lüftergehäuse 6 ist eine Zahnscheibe 31 mittels dreier Schrauben 32 befestigt. Zur Sicherung gegen Verdrehen und zur Zentrierung hat die Zahnscheibe 31 in entsprechende Aussparungen im Lüftergehäuse 5 eingreifende Zapfen 33. Statt mittels Schrauben 32 kann die Zahnscheibe auch mittels Schnappverschlüssen am Lüftergehäuse 6 befestigt sein. Auf der der Zwischenscheibe 17 zugewandten Seite trägt die Zahnscheibe 31 zwei Reib- oder Zahnkränze 34, 35 von unterschiedlichem Durchmeser, die mit den Zahnkränzen 21, 22 auf der Zwischenscheibe 17 in Eingriff bringbar sind. Die Zahnkränze 34, 35 sind entweder in Kunststoff oder in einem verschleißfesten Metall ausgeführt, so daß sich mit den Zahnkränzen 21, 22 jeweils eine Metall-Kunststoffpaarung ergibt, bei der ein Verschleiß nur an der leicht auswechselbaren Kunststoffverzahnung auftreten kann. Es besteht die Beziehung, duß der Betrag der Differenz der Teilkreisdurchmesser der Zahnkränze 22 und 34 sowie der Betrag der Differenz der Teilkreisdurchmesser der Zahnkränze 21 und 35 jeweils dem Zweifachen der Exzentrizität X entspricht. Statt gezahnter Kränze 21, 22, 34, 35 können auch Reibkränze, z.B. mit einer Gummiauflage, Verwendung finden.A toothed disc 31 is fastened to the fixed fan housing 6 by means of three screws 32. To prevent rotation and for centering, the toothed disk 31 has pins 33 which engage in corresponding recesses in the fan housing 5. Instead of using screws 32, the toothed disk can also be fastened to the fan housing 6 by means of snap locks. On the side facing the intermediate disk 17, the toothed disk 31 carries two friction or toothed rings 34, 35 of different diameters, which can be brought into engagement with the toothed rings 21, 22 on the intermediate disk 17. The sprockets 34, 35 are either made of plastic or in a wear-resistant metal, so that each with the sprockets 21, 22 results in a pair of metal and plastic, in which wear can only occur on the easily replaceable plastic teeth. There is a relationship that the amount of the difference of the pitch circle diameters of the ring gears 22 and 34 and the amount of the difference of the pitch circle diameters of the ring gears 21 and 35 each correspond to twice the eccentricity X. Instead of toothed rings 21, 22, 34, 35, friction rings, e.g. with a rubber pad, find use.

In Figur 2 ist eine zweite Zwischenscheibe 37 gezeigt, die am Umfang Kränze 38, 39 aufweist, die den Zahnkränzen 34, 35 an der Zwischenscheibe 17 entsprechen, aber zahnlos sind. Im Mittelbereich weist die Zwischenscheibe 37 genauso wie die Zwischenscheibe 17 beidseits je einen erhabenen Ring 40 sowie eine zentrale vierkantige Durchbrechung 41 auf. Die Lüftungsdurchbrüche 42 entsprechen den Durchbrüchen 20. Auf einer seiner beiden Seiten trägt die Zwischenscheibe 37 sich radial von dem Ring 40 nach außen erstreckende Stege 43, die formschlüssig in Aussparungen 44 am Lüfterrad 8 eingesetzt werden können. Dadurch entsteht eine drehfeste Verbindung zwischen dem Lüfterrad 8 und der Zwischenscheibe 37. Auf der nicht gezeigten hinteren Seite fehlen die Stege 43, so daß die Zwischenscheibe 37, wenn sie mit der Hinterseite dem Lüfterrad 8 zugewandt ist, sich ohne Kontakt damit frei drehen kann, wie dies auch bei der Zwischenscheibe 17 der Fall ist (siehe Figur 1).FIG. 2 shows a second intermediate disk 37 which has rings 38, 39 on the circumference which correspond to the toothed rings 34, 35 on the intermediate disk 17, but are toothless. In the central region, the intermediate disk 37, like the intermediate disk 17, has a raised ring 40 on both sides and a central square opening 41. The ventilation openings 42 correspond to the openings 20. On one of its two sides, the intermediate disk 37 carries webs 43 which extend radially outward from the ring 40 and which can be inserted in a form-fitting manner in recesses 44 on the fan wheel 8. This creates a rotationally fixed connection between the fan wheel 8 and the intermediate disk 37. The webs 43 are missing on the rear side, not shown, so that the intermediate disk 37, when it faces the fan wheel 8 with the rear side, can rotate freely without contact with it, as is also the case with the intermediate disk 17 (see FIG. 1).

In Figur 3 ist die Anordnung der Lüftungsdurchbrüche 28 in dem Schleifteller 24 gezeigt. Sechs der Durchbrüche sind auf einem Durchmesser 46 von ca. 80 mm und ca. acht Durchbrüche 47 auf einem Durchmeser von ca. 65 mm kreissymmetrisch angeordnet.The arrangement of the ventilation openings 28 in the grinding plate 24 is shown in FIG. Six of the openings are arranged in a circular symmetry on a diameter 46 of approximately 80 mm and approximately eight openings 47 on a diameter of approximately 65 mm.

Die Funktion des Exzenterschleifers ist bereits in der DE-OS 36 09 441 beschrieben. Genau wie dort sind auch hier mit der Zwischenscheibe 17 zwei unterschiedlich feine Schleifbewegungen möglich. Bei Eingriff des Zahnkranzes 22 in den Zahnkranz 34 ergibt sich eine mittelgrobe Schleifbewegung mit der Exzenterbewegung entgegengesetzter Rotationsbewegung des Schleiftellers. Bei Eingriff des Zahnkranzes 21 in den Zahnkranz 35 wird eine grobe Schleifbewegung erzeugt, bei der die Rotationsbewegung des Schleiftellers gleichgerichtet ist mit der Exzenterbewegung.The function of the random orbit sander has already been described in DE-OS 36 09 441. Just as there, two differently fine grinding movements are possible with the intermediate disc 17. When the ring gear 22 engages in the ring gear 34, a medium-rough grinding movement results with the eccentric movement in the opposite rotational movement of the grinding plate. When the ring gear 21 engages in the ring gear 35, a rough grinding movement is generated, in which the rotational movement of the grinding plate is aligned with the eccentric movement.

Mit der Zwischenscheibe 37 lassen sich ebenfalls zwei verschiedene Schleifbewegungen erzeugen, eine feine, wenn sich die Zwischenscheibe frei drehen kann und eine sehr grobe, wenn die Stege 43 im Eingriff mit den Aussparungen 44 des Lüfterrads stehen.Two different grinding movements can also be produced with the intermediate disk 37, a fine one if the intermediate disk can rotate freely and a very coarse one if the webs 43 are in engagement with the recesses 44 of the fan wheel.

Wird beim Schleifvorgang Druck auf den Rand des Schleiftellers 24 ausgeübt, so biegt sich dieser zum Lüftergehäuse 6 hin nach innen. Dies wird ermöglicht durch einen Spalt von ca. 1 - 2 mm zwischen der Innenseite des Schleiftellers 24 und dem jeweils dem Schleifteller zugewandten Kranz 21, 22, 38, 39. Ein zu starkes Verbiegen des Schleiftellers wird andererseits dadurch verhindert, daß der Schleifteller an dem Kranz 21, 22, 38, 39 einen Anschlag findet.If pressure is exerted on the edge of the grinding plate 24 during the grinding process, it bends inwards toward the fan housing 6. This is made possible by a gap of approx. 1 - 2 mm between the The inside of the grinding plate 24 and the ring 21, 22, 38, 39 facing the grinding plate. On the other hand, excessive bending of the grinding plate is prevented by the grinding plate finding a stop on the ring 21, 22, 38, 39.

Das Lüfterrad 8 erfüllt mehrere Funktionen. Neben der Erzeugung der Exzenterbewegung und des Ausgleichs von Unwuchten erzeugt es einen Saugluftstrom, der gleichzeitig zur Kühlung der Lager und der Getriebe dient. Schleifstaubbeladene Luft wird durch die Lüftungsdurchbrüche 29 und 28 im Schleifteller sowie 20 in der Zwischenscheibe angesaugt und über den Abluftstutzen 7 wieder abgegeben. Durch den Lüftungsstrom wird gleichzeitig die Zwischenscheibe 17 bzw. 37 gekühlt, an die die in den Lagern 10 und 11 entstehende Wärme über die Exzenterwelle 12 abgegeben wird.The fan wheel 8 fulfills several functions. In addition to generating the eccentric movement and compensating for unbalance, it generates a suction air flow that also serves to cool the bearings and the gears. Grinding dust-laden air is sucked in through the ventilation openings 29 and 28 in the grinding plate and 20 in the intermediate disc and released again via the exhaust air connector 7. At the same time, the intermediate disk 17 or 37 is cooled by the ventilation flow, to which the heat generated in the bearings 10 and 11 is released via the eccentric shaft 12.

Das Ansaugen von Falschluft durch den Spalt zwischen Schleifteller 24 und Lüftergehäuse 6 wird durch die Labyrinthwirkung des Bundes 26 am Schleifteller und des jeweils dem Schleifteller zugewandten Kranz 21, 22, 38, 39 der Zwischenscheibe 17, 37 weitgehend verhindert.The intake of false air through the gap between the grinding plate 24 and the fan housing 6 is largely prevented by the labyrinth effect of the collar 26 on the grinding plate and the rim 21, 22, 38, 39 of the intermediate disc 17, 37 facing the grinding plate.

Die Erfindung beschränkt sich nicht auf das gezeigte Ausführungsbeispiel. Statt der beiden umwendbaren Zwischenscheiben 17 und 37 können auch vier einzelne Scheiben verwendet werden, die jede mit einem eigenen Schleifteller im Mittelbereich fest verbunden sein kann. Dies würde auch zu einer flacheren Bauweise des Schleifers führen.The invention is not limited to the exemplary embodiment shown. Instead of the two reversible intermediate discs 17 and 37, four individual discs can also be used, each of which can be firmly connected to its own grinding plate in the central area. This would also result in a flatter design for the grinder.

Die vier Schleifbewegungen können aber auch mittels einer einzigen Zwischenscheibe erzeugt werden, die die beiden unterschiedlich großen Zahnkränze auf derselben Seite trägt und deren in das Lüfterrad einlegbare Stege bei der feinen, mittelgroben und groben Schleifbewegung lösbar, zurückklappbar oder von außen schaltbar sind. In diesem Fall wären die drehfest mit dem Gehäuse verbundenen Zahnkränze axial verschieblich, so daß entweder der eine, der andere oder keiner der beiden mit den Zahnkränzen der Zwischenscheibe in Eingriff kommen. Das hat den Vorteil, daß die unterschiedlichen Schleifbewegungen ohne Abnahme des Schleiftellers von außen eingestellt werden können.The four grinding movements can also be generated by means of a single washer, which carries the two differently sized sprockets on the same side and whose webs that can be inserted into the fan wheel are detachable, foldable or switchable from the outside during the fine, medium-sized and rough grinding movement. In this case, they would be non-rotatably connected to the housing Sprockets axially displaceable so that either one, the other or neither of the two come into engagement with the sprockets of the washer. This has the advantage that the different grinding movements can be adjusted from the outside without removing the grinding plate.

Claims (10)

  1. Eccentric sander comprising an eccentric shaft and a device for varying the sanding movement of its backing pad, having at least one fixed friction or toothed rim, the backing pad (24) being connected in its centre area to the eccentric shaft in such a way as to be locked in terms of rotation, and the outer area of the backing pad (24) being arranged without connection to the remaining parts of the sander and at an axial distance therefrom, characterised in that a reversible intermediate disc (17) is arranged between the housing (6) of the sander and the backing pad (24), which intermediate disc (17) is provided with at least one friction or toothed rim (21, 22) which, in contact with one of the fixed friction or toothed rims (34, 35), produces a rotary movement of the backing pad (24) in addition to the eccentric movement, and in that the intermediate disc (17) is connected to the centre area of the backing pad (24) in such a way as to be locked in terms of rotation.
  2. Eccentric sander according to Claim 1, characterised in that the intermediate disc can be exchanged for another.
  3. Eccentric sander according to Claim 1, characterised in that at least two fixed friction or toothed rims (34, 35) are connected to its housing, and two types of friction or toothed rim (21, 22) are arranged on the inserted intermediate disc (17,37), one type acting radially outwards and the other type acting radially inwards, which, in interaction with the fixed toothed rims (34, 35), produces a rotary movement of the backing pad (24) different in its speed from the other rotary movement.
  4. Eccentric sander according to one of Claims 1 to 3, characterised in that the eccentric shaft (9) has a non-circular, in particular square, end section (13) onto which both the intermediate disc (17, 37) and the backing pad (24) can be releasably slipped in a positive-locking manner.
  5. Eccentric sander according to Claim 4, characterised in that the intermediate disc (17, 37) has a central aperture (25,41) having the non-circular shape of the end section (13) of the eccentric shaft (9), and the backing pad (24) is supported in the centre area (23) around the ring (19, 40) on the intermediate disc (17, 37).
  6. Eccentric sander according to one of the preceding claims, characterised in that the intermediate disc (17, 37) is in contact with the eccentric shaft (9) and has ventilation apertures (20, 42) through which air can flow from the ventilation apertures (28) in the backing pad (24) to a fan wheel (8).
  7. Eccentric disc according to one of the preceding claims, characterised in that a different interchangeable intermediate disc (37) has toothless rims and, on one of its sides, four raised webs (43) which extend radially outwards from the ring (40) and engage in a positive-locking manner in recesses (44) on the fan wheel (8).
  8. Eccentric sander according to one of the preceding claims, characterised in that the intermediate disc (17, 37) is made of metal, in particular an aluminium die casting, and the toothed rims (34, 35) firmly connected to the housing (6) are made of plastic and can easily be exchanged in the event of wear.
  9. Eccentric sander according to one of Claims 1 to 6, characterised in that the disc (17) made of metal has toothed rims of plastic, and the toothed rims (34, 35) firmly connected to the housing (6) are made of metal.
  10. Eccentric sander according to one of the preceding claims, characterised in that the backing pad (24) has fourteen ventilation apertures (28), of which six are arranged in a symmetric circle on a diameter of about 80 mm and eight are arranged in a symmetric circle on a diameter of about 65 mm.
EP89901938A 1988-03-24 1989-02-02 Eccentric grinding machine Expired - Lifetime EP0406247B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3809930A DE3809930A1 (en) 1988-03-24 1988-03-24 Eccentric grinder
DE3809930 1988-03-24

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EP0406247A1 EP0406247A1 (en) 1991-01-09
EP0406247B1 true EP0406247B1 (en) 1992-12-02

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EP89901938A Expired - Lifetime EP0406247B1 (en) 1988-03-24 1989-02-02 Eccentric grinding machine

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US (2) US5170588A (en)
EP (1) EP0406247B1 (en)
DE (2) DE3809930A1 (en)
WO (1) WO1989009114A1 (en)

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Also Published As

Publication number Publication date
EP0406247A1 (en) 1991-01-09
US5453040A (en) 1995-09-26
DE3809930A1 (en) 1989-10-05
WO1989009114A1 (en) 1989-10-05
US5170588A (en) 1992-12-15
DE58902911D1 (en) 1993-01-14

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