EP0303955B1 - Portable sander - Google Patents

Portable sander Download PDF

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Publication number
EP0303955B1
EP0303955B1 EP88112981A EP88112981A EP0303955B1 EP 0303955 B1 EP0303955 B1 EP 0303955B1 EP 88112981 A EP88112981 A EP 88112981A EP 88112981 A EP88112981 A EP 88112981A EP 0303955 B1 EP0303955 B1 EP 0303955B1
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EP
European Patent Office
Prior art keywords
shaft
axis
bodies
eccentric
grinding
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EP88112981A
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German (de)
French (fr)
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EP0303955A1 (en
Inventor
Miksa Marton
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Individual
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Individual
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Priority to AT88112981T priority Critical patent/ATE63710T1/en
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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
    • B24B41/00Component parts such as frames, beds, carriages, headstocks
    • B24B41/04Headstocks; Working-spindles; Features relating thereto
    • B24B41/042Balancing mechanisms
    • 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

Definitions

  • the invention relates to a hand-held grinding machine with a motor-driven shaft, a grinding plate rotatably connected to the shaft, the axis of rotation of which is arranged eccentrically to the axis of the shaft, and an adjustable counterweight connected to the shaft, which compensates for the unbalance caused by the eccentric arrangement of the grinding plate .
  • Such a hand grinder is known for example from DE-OS 27 45 129.
  • the grinding plate does not rotate, but is guided on a circular path, which is due to the eccentric connection between the driven shaft and the grinding plate.
  • Such machines are mainly used for fine grinding because the translatory movement of the grinding plate on a circular path does not give rise to any grinding marks
  • the eccentric arrangement of the grinding plate to the driven shaft results in an imbalance which must be compensated for by a counterweight.
  • the counterweight is formed by a body which is detachably fastened to the end face of the end of the driven shaft adjacent to the grinding plate by means of screws. Instead, the counterweight could also be slidably attached.
  • the grinding plate itself is mounted in a recess arranged eccentrically in the end of the shaft. It goes without saying that the radial rays running through the shaft axis, to which the counterweight and the eccentric recess are arranged symmetrically, are directed opposite to one another with respect to the shaft axis.
  • Hand grinders of the type described are operated with interchangeable sanding sheets which are attached to the outside of the sanding plate.
  • the mass of the sanding sheet to be attached to the sanding plate can be taken into account when dimensioning the counterweight, it is possible to use different sanding sheets adapted to different work in connection with the sanding plate, which also have a different mass, so that depending on the type There may be certain imbalances in the abrasive sheet used, which, at the very high speeds with which such hand-held grinders usually work, can be very unpleasant and can seriously impair the well-being of a worker using a machine.
  • the invention has for its object to ensure with simple and captive means that the sanding plate can always be properly balanced with the sanding sheet used and without the temptation to refrain from balancing. It should even be possible to use not only sanding sheets of different designs, but also sanding plates with different structures and / or different sizes, without causing the machine to vibrate harmfully due to imbalances.
  • the counterweight comprises two identical adjustable bodies whose centers of gravity are arranged symmetrically to the axis of symmetry connecting the shaft axis and the eccentric axis of rotation.
  • the center of gravity of the two counterweights during rotation of the shaft result in a resulting radial force directed along the axis of symmetry, the size of which depends not only on the mass of the body itself, but also on its angular position with respect to the axis of symmetry of the arrangement.
  • the counterforce required to compensate for the imbalance which also generates a radial force coinciding with the axis of symmetry, can be set very precisely. Therefore, the invention offers the possibility, by changing the angular position of the adjustable body, to compensate for even small imbalances in the sanding plate with its sanding sheet. The adjustment of the body is possible without great effort, so that it is also made by the user of such a hand-held grinder, and the counterweights cannot be lost either because they generally remain connected to the machine and not for everyone Sanding disc special counterweights must be provided.
  • a particular advantage of the design of the hand grinder according to the invention is that the adjustable bodies do not have to form the counterweight alone, but also in addition to a body that is firmly connected to the shaft can find, the position and size of which is such that it compensates for the imbalance of a grinding plate of a given medium size.
  • the radial force exerted by this body, which is firmly connected to the shaft, can then not only be increased by the two adjustable bodies, but can also be reduced if the two adjustable bodies are located on the opposite side of the axis of rotation of the shaft with respect to the fixed body.
  • the adjustable bodies can be screwed into the shaft from the outside and a number of threaded bores can be arranged on the circumference of the shaft, which allow the screwing in of the bodies in several positions, from which the position best suited for compensation can be selected. It would also be conceivable to arrange several parallel rings of such threaded holes, which are intended for screwing in adjustable bodies of different sizes, of which the larger bodies allow a coarse adjustment, which enables the use of grinding plates of different sizes, while smaller screw-in bodies make fine adjustment to compensate Allow differences between sanding pads of the same type and / or to adapt to different sanding sheets.
  • a particularly simple embodiment of the invention which enables the bodies to be continuously adjusted, consists in that two adjusting rings with center of gravity eccentric to the shaft axis are arranged axially one behind the other on a cylindrical section of the shaft. Then, by simply turning and fixing the adjusting rings, the eccentric centers of gravity can be continuously distributed over the two sides of the symmetry axis mentioned at the outset so that the unbalance caused by the sanding plate with the sanding sheet is completely compensated for.
  • the adjusting rings used in this embodiment of the invention can be designed in very different ways.
  • such adjusting rings could be formed by tensioning straps, the tensioning devices of which form a concentrated mass which can be adjusted along the circumference of the shaft.
  • massive adjusting rings can be used, which have an approach that forms the adjustable eccentric mass on their outside. This approach can also be used to accommodate a radial set screw.
  • adjusting rings with a circular contour are used which have an eccentric bore.
  • Such collars are particularly easy to manufacture and have good stability.
  • the set screw for fixing the set rings can be arranged at the point where the set rings have the greatest wall thickness.
  • the adjusting rings can be provided with a scale that interacts with a reference mark attached to the outer surface of the shaft, or vice versa.
  • the scale can also denote the positions that the rings must theoretically have when using different sanding plates and / or sanding sheets.
  • sets of rings with different eccentric masses can compensate for the imbalance of different grinding discs on the one hand and different grinding wheels on the other.
  • a combination of collars and screw-in bodies is of course also possible.
  • the bores for the screw-in bodies could also be provided with markings which indicate the position in which these bodies are to be placed when using certain grinding plates and / or sanding sheets.
  • a preferred embodiment of the invention provides that the adjustable bodies and / or the shaft are provided with selected markings associated with the bodies.
  • the shaft has a central threaded bore at one end for receiving the threaded pin of a motor shaft and an eccentric recess at the other end, in which the bearing for the grinding plate is arranged.
  • an eccentric section with an enlarged diameter is arranged at the end of the shaft adjacent to the grinding plate, said section being directed opposite to the eccentric bearing for the grinding plate with respect to the axis of the shaft.
  • the adjustable bodies are arranged on the section of the shaft adjoining the eccentric section
  • a shaft 1 to 3 has a shaft 1, which is provided at one end with a concentric threaded bore 2, which allows the shaft 1 at the end of the motor shaft 3, which is only shown in broken lines in FIG. 1, to the hand grinder fasten.
  • a cylindrical recess 4 which is arranged eccentrically to the threaded bore 2.
  • the offset between the axis 5 of the shaft 1 and the axis 6 of the eccentric recess 4 is denoted by e in FIG. 1.
  • the grinding plate 7 is moved by the shaft 1 rotating about its axis 5 on a circular path with the radius e, without itself rotating about its axis 6, because the rotatable mounting of the grinding plate 7 in the recess 4 of the shaft 1 prevents it , which could transmit a torque to the sanding plate 7 that would be sufficient to overcome the forces opposing rotation of the sanding plate 7 that occur during grinding.
  • the end of the shaft 1 adjacent to the grinding plate 7 is provided with a section 21 of larger diameter in the illustrated embodiment, which is arranged eccentrically to the axis 5 of the shaft 1 in such a way that it causes an unbalance caused by the grinding plate 7 opposite radial force is generated.
  • the axis 22 of the section 21 is accordingly located on the side of the axis 5 of the shaft 1 opposite the axis 6 of the grinding plate 7 on the same straight line intersecting the axis 5 of the shaft 1, which forms an axis of symmetry 23 of the arrangement.
  • the shaft 1 has a section 24 of reduced diameter at its end facing away from the grinding plate, which is also arranged slightly eccentrically to the axis 5 of the shaft 1, but in the same sense as the grinding plate 7. This smaller section enables the shaft 1 to be manufactured fine tuning of the unbalance caused by the eccentric sections 21, 24 to a predetermined value.
  • the unbalance of the shaft 1 is adjusted in such a way that it compensates for the unbalance of a certain size and type of grinding plate 7 provided with a sanding sheet 12 as well as possible.
  • grinding discs of different designs depending on the grinding work to be performed, for example different sizes and / or different hardness and thus different masses.
  • sanding sheets with different backing material and different grain sizes, which can differ considerably in their mass.
  • the counterweight connected to shaft 1 does not only consist of section 21 with an enlarged diameter, but additionally comprises two adjustable bodies in the form of actuators rings 31, 32, which have a circular contour and an eccentric bore.
  • These adjusting rings 31, 32 are arranged axially one behind the other on the central, cylindrical section of the shaft 1. Because of their eccentric bore, they each have a center of gravity eccentric with respect to the axis 5 of the shaft 1, the position of which can be moved on a circular path concentric with the shaft axis 5 by rotating the adjusting rings 31, 32.
  • the two adjusting rings 31, 32 can be adjusted by means of adjusting screws 33, 34 penetrating them radially in any angular position to the shaft 1 and thus also to the axis of symmetry 23 connecting the shaft axis 5, the axis 6 of the grinding plate 7 and also the axis 22 of the eccentric extension 21 .
  • adjusting screws 33, 34 penetrating them radially in any angular position to the shaft 1 and thus also to the axis of symmetry 23 connecting the shaft axis 5, the axis 6 of the grinding plate 7 and also the axis 22 of the eccentric extension 21 .
  • a graduation 35, 36 which is opposite a line mark 37 on the circumference of the shaft 1 and a line mark 38 on the top of the eccentric section 21.
  • These marks 37, 38 lie in the plane defined by the axis of symmetry 23 and the shaft axis 5.
  • the scales 35, 36 attached to the circumference of the adjusting rings 31, 32 contain information about the positions which are assigned to certain grinding plates and / or grinding sheets. Furthermore, the scales facilitate a precisely symmetrical setting of the adjusting rings with respect to the axis of symmetry 23.
  • the bodies 41, 42 used instead of eccentric adjusting rings which can be rotated on the shaft are bodies which are fastened to the peripheral surface of the shaft 51 and which have threaded pins, not shown, on their end facing the shaft 51 which they are screwed into corresponding threaded bores 43, 44 which are distributed over the circumference of the shaft 51.
  • the bodies 41, 42 have such a different mass that moving the smaller bodies 42 over the entire range of variation of approximately 180 ° corresponds to moving the larger bodies 41 from one position to another, so that the choice of the position of both bodies makes them very fine Matching is possible, although these bodies can only be moved by discrete amounts.
  • the arrangement can also be such that the threaded bores 43 for the larger bodies 41 are assigned to different grinding plates, whereas the smaller bodies 42 can serve to compensate for the imbalances caused by the use of different grinding sheets.
  • the threaded bores 43, 44 are designated with markings 45, 46 in the form of numbers, letters and other symbols which allow the respective position of the screw-in bodies 41, 42 to be assigned to specific grinding plates and / or grinding wheels.
  • FIG. 6 shows the shaft 51 and the grinding plate 52 in a viewing direction perpendicular to the axis of symmetry 23 according to FIG. 4, similar to the section according to FIG. 1, so that only the bodies 41, 42 arranged on one side of the axis of symmetry in the plane of the drawing are visible are. It is therefore understood that the same arrangement of bodies 41, 42 is present on the rear side of the shaft 51, which is not visible in FIGS. 6 and 6, and care must be taken to ensure that the bodies 41 and 42, which are present in pairs, are symmetrical about the axis of symmetry mentioned to be ordered.
  • a hand grinder characterized in that the adjustable bodies (31, 32; 41, 42) and / or the shaft (1, 21) are provided with markings (35, 36, 37, 38 ; 41, 46) associated with selected positions of the bodies.
  • a hand grinder characterized in that the shaft (1) has at one end a central screw-threaded bore (2) to receive the threaded joumal of a motor shaft (3) and has atthe other end an eccentric recess (4) in which there is disposed a bearing arrangementforthe grinding plate (7) and, at the end adjacent the grinding plate (7), an eccentric portion (21) of enlarged diameter which, in relation to the axis ( 5) of the shaft (1), is directed in opposition to the eccentric bearing for the grinding plate (7) and in that the adjustable bodies (31, 32) are disposed on the portion of the shaft (1) adjacent the eccentric portion (21).

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
  • Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)
  • Surgical Instruments (AREA)
  • Dry Shavers And Clippers (AREA)
  • Control And Other Processes For Unpacking Of Materials (AREA)
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  • Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
  • Saccharide Compounds (AREA)
  • Power Steering Mechanism (AREA)
  • Valve Device For Special Equipments (AREA)
  • Lens Barrels (AREA)
  • Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
  • Heat-Pump Type And Storage Water Heaters (AREA)
  • Materials For Photolithography (AREA)
  • High-Pressure Fuel Injection Pump Control (AREA)
  • Gyroscopes (AREA)
  • Testing Of Balance (AREA)

Abstract

Portable sanders with an abrasive disc moving on a circular path (orbital sanders) are susceptible to pronounced vibrations as a result of a lack of balancing of the eccentrically moving abrasive disc. According to the invention, two identical adjustable bodies are arranged on the shaft of the portable sander, the mass centres of which are arranged symmetrically to the axis of symmetry connecting the shaft axis and the rotational axis eccentric to it. These adjustable bodies can in particular be eccentric adjusting rings. They form part of a counterweight, the action of which can be precisely adjusted to the out-of-balance to be compensated by changing the position of these bodies. <IMAGE>

Description

Die Erfindung betrifft eine Handschleifmaschine mit einer motorisch angetriebenen Welle, einem mit der Welle drehbar verbundenen Schleifteller, dessen Drehachse exzentrisch zur Achse der Welle angeordnet ist, und einem mit der Welle verbundenen, verstellbaren Gegengewicht, das die durch die exzentrische Anordnung des Schleiftellers bedingte Unwucht ausgleicht.The invention relates to a hand-held grinding machine with a motor-driven shaft, a grinding plate rotatably connected to the shaft, the axis of rotation of which is arranged eccentrically to the axis of the shaft, and an adjustable counterweight connected to the shaft, which compensates for the unbalance caused by the eccentric arrangement of the grinding plate .

Eine solche Handschleifmaschine ist beispielsweise aus der DE-OS 27 45 129 bekannt. Bei dieser Handschleifmaschine führt der Schleifteller keine Rotation aus, sondern wird auf einer Kreisbahn geführt, die durch die exzentrische Verbindung zwischen der angetriebenen Welle und dem Schleifteller bedingt ist. Solche Maschinen werden vornehmlich zum Feinschleifen benutzt, weil die translatorische Bewegung des Schleiftellers auf einer Kreisbahn keinedei Schleifriefen entstehen läßtSuch a hand grinder is known for example from DE-OS 27 45 129. In this hand-held grinding machine, the grinding plate does not rotate, but is guided on a circular path, which is due to the eccentric connection between the driven shaft and the grinding plate. Such machines are mainly used for fine grinding because the translatory movement of the grinding plate on a circular path does not give rise to any grinding marks

Es ist ohne weiteres ersichtlich, daß die exzentrische Anordnung des Schleiftellers zur angetriebenen Welle eine Unwucht zur Folge hat, die durch ein Gegengewicht ausgeglichen werden muß. Bei der bekannten Handschleifmaschine wird das Gegengewicht von einem Körper gebildet, der auf die Stirnfläche des dem Schleifteller benachbarten Endes der angetriebenen Welle mittels Schrauben lösbar befestigt ist. Statt dessen könnte das Gegengewicht auch verschiebbar angebracht sein. Der Schleifteller selbst ist in einer in dem Ende der Welle exzentrisch angeordneten Aussparung gelagert. Es versteht sich, daß die durch die Wellenachse verlaufenden Radialstrahlen, zu denen das Gegengewicht und die exzentrische Aussparung symmetrisch angeordnet sind, in bezug auf die Wellenachse zueinander entgegengesetzt gerichtet sind.It is readily apparent that the eccentric arrangement of the grinding plate to the driven shaft results in an imbalance which must be compensated for by a counterweight. In the known hand-held grinding machine, the counterweight is formed by a body which is detachably fastened to the end face of the end of the driven shaft adjacent to the grinding plate by means of screws. Instead, the counterweight could also be slidably attached. The grinding plate itself is mounted in a recess arranged eccentrically in the end of the shaft. It goes without saying that the radial rays running through the shaft axis, to which the counterweight and the eccentric recess are arranged symmetrically, are directed opposite to one another with respect to the shaft axis.

Bei einer anderen, aus der US-PS 27 51 725 bekannten Handschleifmaschine ist an dem dem Schleifteller benachbarten Ende der angetriebenen Welle ein im wesentlichen halbkreisförmiges Gegengewicht starr befestigt. Der Schleifteller selbst ist auf einem mit der Welle verbundenen Exzenter gelagert.In another hand grinding machine known from US Pat. No. 2,751,725, an essentially semicircular counterweight is rigidly attached to the end of the driven shaft adjacent to the grinding plate. The grinding plate itself is mounted on an eccentric connected to the shaft.

Handschleifmaschinen der beschriebenen Art werden mit auswechselbaren Schleifblättern betrieben, die an der Außenseite des Schleiftellers angebracht sind. Zwar kann bei der Bemessung des Gegengewichtes die Masse des am Schleifteller zu befestigenden Schleifblattes berücksichtigt werden, jedoch besteht die Möglichkeit, in Verbindung mit dem Schleifteller unterschiedlichen Arbeiten angepaßte unterschiedliche Schleifblätter zu verwenden, die auch eine unterschiedliche Masse haben, so daß in Abhängigkeit von der Art des verwendeten Schleifblattes gewisse Unwuchten vorhanden sein können, die bei den sehr hohen Drehzahlen, mit denen solche Handschleifgeräte gewöhnlich arbeiten, sehr unangenehm sein und das Wohlbefinden eines eine Maschine benutzenden Arbeiters stark beeinträchtigen können. Zwar ist es möglich, bei der eingangs behandelten Schleifmaschine jedem Schleifteller ein eigenes Gegengewicht zuzuordnen, das zusammen mit dem Schleifteller ausgewechselt werden kann, jedoch ist däs Auswechseln des Gegengewichtes nicht nur lästig, so daß es häufig unterbleibt, sondern es kann das dem Schleifteller zugeordnete Gegengewicht leicht verloren gehen, so daß in der Praxis die den Schleiftellern zugeordneten Gegengewichte überhaupt nicht zur Verfügung stehen.Hand grinders of the type described are operated with interchangeable sanding sheets which are attached to the outside of the sanding plate. Although the mass of the sanding sheet to be attached to the sanding plate can be taken into account when dimensioning the counterweight, it is possible to use different sanding sheets adapted to different work in connection with the sanding plate, which also have a different mass, so that depending on the type There may be certain imbalances in the abrasive sheet used, which, at the very high speeds with which such hand-held grinders usually work, can be very unpleasant and can seriously impair the well-being of a worker using a machine. Although it is possible to assign a separate counterweight to each grinding plate in the grinding machine discussed at the outset, which can be replaced together with the grinding plate, changing the counterweight is not only annoying, so that it is often omitted, but it can also be the counterweight assigned to the grinding plate are easily lost, so that in practice the counterweights assigned to the grinding plates are not available at all.

Demgemäß liegt der Erfindung die Aufgabe zugrunde, mit einfachen und unverlierbaren Mitteln dafür Sorge zu tragen, daß der Schleifteller mit dem verwendeten Schleifblatt stets einwandfrei und ohne zum Unterlassen des Auswuchtens verleitende Mühe ausgewuchtet werden kann. Dabei soll sogar die Möglichkeit bestehen, nicht nur Schleifblätter unterschiedlicher Ausbildung, sondern auch Schleifteller mit unterschiedlichem Aufbau und/oder unterschiedlicher Größe zu verwenden, ohne daß es dadurch zu einem schädliche Vibrieren der Maschine durch Unwuchten kommt.Accordingly, the invention has for its object to ensure with simple and captive means that the sanding plate can always be properly balanced with the sanding sheet used and without the temptation to refrain from balancing. It should even be possible to use not only sanding sheets of different designs, but also sanding plates with different structures and / or different sizes, without causing the machine to vibrate harmfully due to imbalances.

Diese Aufgabe wird nach der Erfindung dadurch gelöst, daß das Gegengewicht zwei gleiche verstellbare Körper umfaßt, deren Massenschwerpunkte symmetrisch zu der die Wellenachse und die dazu exzentrische Drehachse verbindenden Symmetrieachse angeordnet sind.This object is achieved according to the invention in that the counterweight comprises two identical adjustable bodies whose centers of gravity are arranged symmetrically to the axis of symmetry connecting the shaft axis and the eccentric axis of rotation.

Bei der erfindungsgemäßen Handschleifmaschine ergeben die Massenschwerpunkte der beiden Gegengewichte bei der Rotation der Welle eine längs der Symmetrieachse gerichtete, resultierende Radialkraft, deren Größe nicht nur von der Masse der Körper selbst, sondern auch von deren Winkellage in bezug auf die Symmetrieachse der Anordnung abhängt. Durch Verändern der Winkellage der beiden verstellbaren Körper läßt sich dabei die zur Kompensation der Unwucht, die ebenfalls eine mit der Symmetrieachse zusammenfallende Radialkraft erzeugt, erforderliche Gegenkraft sehr genau einstellen. Daher bietet die Erfindung die Möglichkeit, durch Verändern der winkellage derverstellbaren Körper einen Ausgleich von selbst geringen Unwuchten des Schleiftellers mit seinem Schleifblatt zu bewirken. Dabei ist die Verstellung der Körper ohne große Mühe möglich, so daß sie von dem Benutzer einer solchen Handschleifmaschine auch gern vorgenommen wird, und es können die Gegengewichte auch nicht verloren gehen, weil sie in aller Regel mit der Maschine stets verbunden bleiben und nicht für jeden Schleifteller besondere Gegengewichte vorgesehen werden müssen.In the hand-held grinder according to the invention, the center of gravity of the two counterweights during rotation of the shaft result in a resulting radial force directed along the axis of symmetry, the size of which depends not only on the mass of the body itself, but also on its angular position with respect to the axis of symmetry of the arrangement. By changing the angular position of the two adjustable bodies, the counterforce required to compensate for the imbalance, which also generates a radial force coinciding with the axis of symmetry, can be set very precisely. Therefore, the invention offers the possibility, by changing the angular position of the adjustable body, to compensate for even small imbalances in the sanding plate with its sanding sheet. The adjustment of the body is possible without great effort, so that it is also made by the user of such a hand-held grinder, and the counterweights cannot be lost either because they generally remain connected to the machine and not for everyone Sanding disc special counterweights must be provided.

Ein besonderer Vorteil der erfindungsgemäßen Ausbildung der Handschleifmaschine besteht darin, daß die verstellbaren Körper nicht allein das Gegengewicht bilden müssen, sondern zusätzlich zu einem mit der Welle fest verbundenen Körper Verwendung finden können, dessen Lage und Größe so bemessen ist, daß er die Unwucht eines Schleiftellers vorgegebener mittlerer Größe ausgleicht. Die von diesem mit der Welle fest verbundenen Körper ausgeübte Radialkraft kann dann durch die beiden verstellbaren Körper nicht nur erhöht, sondern auch vermindert werden, wenn sich die beiden verstellbaren Körper in bezug auf den festen Körper auf der entgegengesetzten Seite der Drehachse der Welle befinden.A particular advantage of the design of the hand grinder according to the invention is that the adjustable bodies do not have to form the counterweight alone, but also in addition to a body that is firmly connected to the shaft can find, the position and size of which is such that it compensates for the imbalance of a grinding plate of a given medium size. The radial force exerted by this body, which is firmly connected to the shaft, can then not only be increased by the two adjustable bodies, but can also be reduced if the two adjustable bodies are located on the opposite side of the axis of rotation of the shaft with respect to the fixed body.

Im einfachsten Fall können die verstellbaren Körpervon außen in die Welle eingeschraubt und auf den Umfang der Welle eine Anzahl Gewindebohrungen angeordnet sein, die das Einschrauben der Körper in mehreren Stellungen ermöglichen, von denen die jeweils die beste Kompensation ergebende Stellung ausgewählt werden kann. Dabei wäre es auch denkbar, mehrere parallele Kränze solcher Gewindebohrungen anzuordnen, die zum Einschrauben von verstellbaren Körpern unterschiedlicher Größe bestimmt sind, von denen die größeren Körper einen Grobabgleich gestatten, der die Verwendung von Schleiftellem unterschiedlicher Größer ermöglicht, während kleinere Einschraubkörper einen Feinabgleich zum Ausgleich von Unterschieden zwischen Schleiftellem gleichen Typs und/oder zur Anpassung an unterschiedliche Schleifblätter gestatten.In the simplest case, the adjustable bodies can be screwed into the shaft from the outside and a number of threaded bores can be arranged on the circumference of the shaft, which allow the screwing in of the bodies in several positions, from which the position best suited for compensation can be selected. It would also be conceivable to arrange several parallel rings of such threaded holes, which are intended for screwing in adjustable bodies of different sizes, of which the larger bodies allow a coarse adjustment, which enables the use of grinding plates of different sizes, while smaller screw-in bodies make fine adjustment to compensate Allow differences between sanding pads of the same type and / or to adapt to different sanding sheets.

Die Verwendung von in die Welle eingeschraubten Körpern zum Verändern der wirksamen Masse des Gegengewichtes erlaubt nur einen schrittweisen Ausgleich einer Unwucht. Obwohl bei geeigneter Bemessung der einschraubbaren Körper und der Lochabstände eine etwaige Unwucht auf ein nicht mehr störendes Maß vermindert werden kann, ist ein vollkommener Ausgleich der Unwucht nur dann möglich, wenn die verstellbaren Körper der erfindungsgemäßen Handschleifmaschine stetig verstellbar sind. Stetig verstellbare Körper lassen sich in vielen Ausführungsformen vorstellen. So können beispielsweise an zwei einander gegenüberliegenden Seiten der Welle geradlinige Führungen angeordnet sein, in denen sich in einer beliebigen Lage feststellbare Gleitkörper befinden. Ebenso könnten derartige Führungen und Gleitkörper am Umfang der Welle angeordnet sein. Eine besonders einfache Ausführungsform der Erfindung, die eine stetige Verstellung der Körper ermöglicht, besteht darin, daß auf einem zylindrischen Abschnitt der Welle axial hintereinander zwei Stellringe mit zur Wellenachse exzentrischen Massenschwerpunkten angeordnet sind. Es lassen sich dann durch einfaches Verdrehen und Fixieren der Stellringe die exzentrischen Massenschwerpunkte stufenlos so auf die beiden Seiten der eingangs erwähnten Symmetrieachse verteilen, daß die von dem Schleifteller mit Schleifblatt verursachte Unwucht vollkommen ausgeglichen wird.The use of bodies screwed into the shaft to change the effective mass of the counterweight only allows gradual balancing of an imbalance. Although, with suitable dimensioning of the screw-in body and the hole spacing, any unbalance can be reduced to a dimension that is no longer disturbing, a perfect compensation of the unbalance is only possible if the adjustable bodies of the hand-held grinder according to the invention are continuously adjustable. Continuously adjustable bodies can be imagined in many designs. For example, linear guides can be arranged on two opposite sides of the shaft, in which there are lockable sliding bodies in any position. Such guides and sliding bodies could also be arranged on the circumference of the shaft. A particularly simple embodiment of the invention, which enables the bodies to be continuously adjusted, consists in that two adjusting rings with center of gravity eccentric to the shaft axis are arranged axially one behind the other on a cylindrical section of the shaft. Then, by simply turning and fixing the adjusting rings, the eccentric centers of gravity can be continuously distributed over the two sides of the symmetry axis mentioned at the outset so that the unbalance caused by the sanding plate with the sanding sheet is completely compensated for.

Die bei dieser Ausführungsform der Erfindung verwendeten Stellringe können in sehr unterschiedlicher Weise ausgebildet sein. Im einfachsten Fall könnten solche Stellringe von Spannbändern gebildet werden, deren Spanneinrichtungen eine konzentrierte Masse bilden, die längs des Umfanges der Welle verstellbar ist. Stattdessen können auch massive Stellringe Verwendung finden, die an ihrer Außenseite einen die verstellbare exzentrische Masse bildenden Ansatz aufweisen. Dieser Ansatz kann gleichzeitig zur Aufnahme einer radialen Stellschraube dienen. Bei einer bevorzugten Ausführungsform der Erfindung finden jedoch Stellringe mit einer kreisrunden Kontur Verwendung, die eine exzentrische Bohrung aufweisen. Solche Stellringe sind auf besonders einfache Weise herstellbar und haben eine gute Stabilität. Dabei kann die Stellschraube zum Fixieren der Stellringe an der Stelle angeordnet werden, an der die Stellringe die größte Wandstärke aufweisen.The adjusting rings used in this embodiment of the invention can be designed in very different ways. In the simplest case, such adjusting rings could be formed by tensioning straps, the tensioning devices of which form a concentrated mass which can be adjusted along the circumference of the shaft. Instead, massive adjusting rings can be used, which have an approach that forms the adjustable eccentric mass on their outside. This approach can also be used to accommodate a radial set screw. In a preferred embodiment of the invention, however, adjusting rings with a circular contour are used which have an eccentric bore. Such collars are particularly easy to manufacture and have good stability. The set screw for fixing the set rings can be arranged at the point where the set rings have the greatest wall thickness.

Um eine gute symmetrische Positionierung der Stellringe zu erleichtern, können die Stellringe mit einer Skala versehen sein, die mit einer auf der Mantelfläche der Welle angebrachten Referenzmarke zusammenwirkt, oder umgekehrt. Dabei kann die Skala auch noch die Stellungen bezeichnen, welche die Ringe theoretisch bei der Verwendung unterschiedlicher Schleifteller und/oder Schleifblätter aufweisen müssen. Dabei ist es auch hier wieder möglich, Sätze von Ringen mit unterschiedlicher exzentrischer Masse zur Kompensation der Unwucht von unterschiedlichen Schleiftellern einerseits und von unterschiedlichen Schleifblättern andererseits zu benutzen. Auch ist natürlich eine Kombination von Stellringen und Einschraubkörpem möglich. Dabei könnten auch die Bohrungen für die Einschraubkörper mit Markierungen versehen sein, die angeben, in welche Stellung diese Körper bei der Verwendung bestimmter Schleifteller und/oder Schleifblätter zu bringen sind. Allgemein sieht demnach eine bevorzugte Ausführungsform der Erfindung vor, daß die verstellbaren Körper und/oder die Welle mit ausgewählten Stellungen der Körper zugeordneten Markierungen versehen sind.In order to facilitate a good symmetrical positioning of the adjusting rings, the adjusting rings can be provided with a scale that interacts with a reference mark attached to the outer surface of the shaft, or vice versa. The scale can also denote the positions that the rings must theoretically have when using different sanding plates and / or sanding sheets. It is also possible to use sets of rings with different eccentric masses to compensate for the imbalance of different grinding discs on the one hand and different grinding wheels on the other. A combination of collars and screw-in bodies is of course also possible. The bores for the screw-in bodies could also be provided with markings which indicate the position in which these bodies are to be placed when using certain grinding plates and / or sanding sheets. In general, therefore, a preferred embodiment of the invention provides that the adjustable bodies and / or the shaft are provided with selected markings associated with the bodies.

Bei einer bevorzugten Ausführungsform einer Handschleifmaschine nach der Erfindung weist die Welle an einem Ende eine zentrische Gewindebohrung zurAufnahme des Gewindezapfens einer Motorwelle und am anderen Ende eine exzentrische Aussparung auf, in der das Lager für den Schleifteller angeordnet ist. Außerdem ist an dem dem Schleifteller benachbarten Ende der Welle ein exzentrischer Abschnitt mit vergrößertem Durchmesser angeordnet, der in bezug auf die Achse der Welle zum exzentrischen Lager für den Schleifteller entgegengesetzt gerichtet ist. Die verstellbaren Körper sind auf dem an den exzentrischen Abschnitt angrenzenden Abschnitt der Welle angeordnetIn a preferred embodiment of a hand-held grinding machine according to the invention, the shaft has a central threaded bore at one end for receiving the threaded pin of a motor shaft and an eccentric recess at the other end, in which the bearing for the grinding plate is arranged. In addition, an eccentric section with an enlarged diameter is arranged at the end of the shaft adjacent to the grinding plate, said section being directed opposite to the eccentric bearing for the grinding plate with respect to the axis of the shaft. The adjustable bodies are arranged on the section of the shaft adjoining the eccentric section

Die Erfindung wird im folgenden anhand der in der Zeichnung dargestellten Ausführungsbeispiele näher beschrieben und erläutert. Die der Beschreibung und der Zeichnung zu entnehmenden Merkmale können bei anderen Ausführungsformen der Erfindung einzeln für sich oder zu mehreren in beliebiger Kombination Anwendung finden. Es zeigen

  • Fig. 1 Einen Längsschnitt durch die für die Erfindung wesentlichen Teile einer Handschleifmaschine nach der Erfindung,
  • Fig. 2 eine Draufsicht auf den in Fig. 1 dargestellten Teil der Handschleifmaschine in Richtung des Pfeiles 11,
  • Fig. 3 eine Seitenansicht des in Fig. 1 dargestellten Teiles der Handschleifmaschine in Richtung des Pfeiles 111,
  • Fig. 4 ein Diagramm, das die Wirkung der bei der Handschleifmaschine nach Fig. 1 vorhandenen verstellbaren Körper des Gegengewichtes veranschaulicht,
  • Fig. 5 ein Diagramm der von dem Gegengewicht erzeugten Radialkraft in Abhängigkeit von der Einstellung der verstellbaren Körper und
  • Fig. 6 eine weitere Ausführungsform einer Handschleifmaschine nach der Erfindung in einer Seitenansicht ähnlich Fig. 3, jedoch unter einer um 90° gegenüber Fig. 3 versetzten Blickrichtung.
The invention is described and explained in more detail below with reference to the exemplary embodiments shown in the drawing. That of the cry Exercise and the drawing features can be used in other embodiments of the invention individually or in combination in any combination. Show it
  • 1 shows a longitudinal section through the parts of a hand-held grinder according to the invention which are essential for the invention,
  • 2 shows a plan view of the part of the hand-held grinding machine shown in FIG. 1 in the direction of arrow 11,
  • 3 shows a side view of the part of the hand-held grinding machine shown in FIG. 1 in the direction of arrow 111,
  • 4 is a diagram illustrating the effect of the adjustable body of the counterweight present in the hand-held grinder according to FIG. 1,
  • Fig. 5 is a diagram of the radial force generated by the counterweight depending on the setting of the adjustable body and
  • 6 shows a further embodiment of a hand grinder according to the invention in a side view similar to FIG. 3, but with a viewing direction offset by 90 ° with respect to FIG. 3.

Die in den Fig. 1 bis 3 dargestellte Handschleifmaschine weist eine Welle 1 auf, die an einem Ende mit einer konzentrischen Gewindebohrung 2 versehen ist, die es gestattet, die Welle 1 am Ende der in Fig. 1 nur strichpunktiert angedeuteten Motorwelle 3 der Handschleifmaschine zu befestigen. Im anderen Ende der Welle befindet sich eine zylindrische Aussparung 4, die zur Gewindebohrung 2 exzentrisch angeordnet ist. Der Versatz zwischen der Achse 5 der Welle 1 und der Achse 6 der exzentrischen Aussparung 4 ist in Fig. 1 mit e bezeichnet. In der exzentrischen Aussparung 4 befindet sich eine Lageranordnung für einen Schleifteller 7, die einen mittels Kugellagern 8, 9 in der Aussparung 4 gelagerten Zapfen 10 umfaßt, der eine zentrale Gewindebohrung 11 zur Aufnahme eines den Schleifteller 7 tragenden Gewindezapfens aufweist. Beim Betrieb der Handschleifmaschine wird der Schleifteller 7 von der um ihre Achse 5 rotierenden Welle 1 auf einer Kreisbahn mit dem Radius e bewegt, ohne selbst eine Drehung um seine Achse 6 auszuführen, weil die drehbare Lagerung des Schleiftellers 7 in derAussparung 4 der Welle 1 verhindert, das auf den Schleifteller 7 ein Drehmoment übertragen könnte, das ausreichend wäre, um die sich einer Drehung des Schleiftellers 7 widersetzenden, beim Schleifen auftretenden Kräfte zu überwinden.1 to 3 has a shaft 1, which is provided at one end with a concentric threaded bore 2, which allows the shaft 1 at the end of the motor shaft 3, which is only shown in broken lines in FIG. 1, to the hand grinder fasten. In the other end of the shaft there is a cylindrical recess 4, which is arranged eccentrically to the threaded bore 2. The offset between the axis 5 of the shaft 1 and the axis 6 of the eccentric recess 4 is denoted by e in FIG. 1. In the eccentric recess 4 there is a bearing arrangement for a grinding plate 7, which comprises a pin 10 which is mounted in the recess 4 by means of ball bearings 8, 9 and which has a central threaded bore 11 for receiving a threaded pin carrying the grinding plate 7. During operation of the hand-held grinding machine, the grinding plate 7 is moved by the shaft 1 rotating about its axis 5 on a circular path with the radius e, without itself rotating about its axis 6, because the rotatable mounting of the grinding plate 7 in the recess 4 of the shaft 1 prevents it , which could transmit a torque to the sanding plate 7 that would be sufficient to overcome the forces opposing rotation of the sanding plate 7 that occur during grinding.

Durch die exzentrische Lagerung des Schleiftellers 7 in der Welle 1 werden auf diese Welle Radialkräfte ausgeübt, die sich in Form von heftigen Vibrationen der Handschleifmaschine bemerkbar machen. Die Größe dieser Radialkräfte oder Unwucht hängt von der Masse des exzentrischen Schleiftellers 7 und seiner Lagerung, dem Bahnradius e und der Drehzahl der Welle 1 ab. Da bei Handschleifmaschinen die Drehzahl sehr hoch ist, beispielsweise im Bereich von 20.000 U/min liegt, kann die Unwucht sehr bedeutend sein und einen Gebrauch der Maschine unmöglich machen.Due to the eccentric mounting of the grinding plate 7 in the shaft 1, radial forces are exerted on this shaft, which are noticeable in the form of violent vibrations in the hand-held grinding machine. The magnitude of these radial forces or imbalance depends on the mass of the eccentric grinding plate 7 and its mounting, the path radius e and the speed of the shaft 1. Since the speed of hand grinders is very high, for example in the range of 20,000 rpm, the imbalance can be very significant and make it impossible to use the machine.

Zur Kompensation der Unwucht ist bei dem dargestellten Ausführungsbeispiel das dem Schleifteller 7 benachbarte Ende der Welle 1 mit einem Abschnitt 21 größeren Durchmessers versehen, der in solcher Weise zur Achse 5 der Welle 1 exzentrisch angeordnet ist, daß er eine zu der vom Schleifteller 7 verursachten Unwucht entgegengesetzte Radialkraft erzeugt. Die Achse 22 des Abschnittes 21 befindet sich demgemäß auf der der Achse 6 des Schleiftellers 7 entgegengesetzten Seite der Achse 5 der Welle 1 auf der gleichen, die Achse 5 der Welle 1 schneidenden Geraden, die eine Symmetrieachse 23 der Anordnung bildet. Weiterhin weist die Welle 1 an ihrem vom Schleifteller abgewandten Ende einen Abschnitt 24 verminderten Durchmessers auf, der ebenfalls leicht exzentrisch zur Achse 5 der Welle 1 angeordnet ist, jedoch im gleichen Sinne wie der Schleifteller 7. Dieser kleinere Abschnitt ermöglicht bei der Herstellung der Welle 1 eine Feinabstimmung der durch die exzentrischen Abschnitte 21, 24 bewirkten Unwucht auf einen vorgegebenen Wert.To compensate for the unbalance, the end of the shaft 1 adjacent to the grinding plate 7 is provided with a section 21 of larger diameter in the illustrated embodiment, which is arranged eccentrically to the axis 5 of the shaft 1 in such a way that it causes an unbalance caused by the grinding plate 7 opposite radial force is generated. The axis 22 of the section 21 is accordingly located on the side of the axis 5 of the shaft 1 opposite the axis 6 of the grinding plate 7 on the same straight line intersecting the axis 5 of the shaft 1, which forms an axis of symmetry 23 of the arrangement. Furthermore, the shaft 1 has a section 24 of reduced diameter at its end facing away from the grinding plate, which is also arranged slightly eccentrically to the axis 5 of the shaft 1, but in the same sense as the grinding plate 7. This smaller section enables the shaft 1 to be manufactured fine tuning of the unbalance caused by the eccentric sections 21, 24 to a predetermined value.

Bei herkömmlichen Handschleifmaschinen ist die Unwucht der Welle 1 so abgestimmt, daß sie die Unwucht eines mit einem Schleifblatt 12 versehenen Schleiftellers 7 bestimmter Größe und Bauart möglichst gut kompensiert. Es besteht jedoch ein Bedarf dafür, in Abhängigkeit von der jeweils zu verrichtenden Schleifarbeit Schleifteller unterschiedlicher Ausbildung zu verwenden, beispielsweise unterschiedlicher Größe und/oder unterschiedlicher Härte und damit unterschiedlicher Masse. Ebenso ist es möglich, Schleifblätter mit unterschiedlichem Trägermaterial und unterschiedlicher Körnung zu verwenden, die sich in ihrer Masse erheblich voneinander unterscheiden können.In conventional hand grinders, the unbalance of the shaft 1 is adjusted in such a way that it compensates for the unbalance of a certain size and type of grinding plate 7 provided with a sanding sheet 12 as well as possible. However, there is a need to use grinding discs of different designs depending on the grinding work to be performed, for example different sizes and / or different hardness and thus different masses. It is also possible to use sanding sheets with different backing material and different grain sizes, which can differ considerably in their mass.

Daher sind die von diesen Schleiftellern oder Schleifblättern ausgeübten Radialkräfte von denjenigen verschieden, auf welche die Unwucht der Welle 1 abgestimmt ist, so daß es dann wieder zu erheblichen, das Arbeiten mit der Handschleifmaschine störenden, wenn nicht sogar unmöglich machenden Vibrationen kommt.Therefore, the radial forces exerted by these grinding plates or grinding blades are different from those to which the unbalance of the shaft 1 is matched, so that there are again considerable vibrations which disrupt, if not make impossible, work with the hand-held grinding machine.

Bei dem in den Fig. 1 bis 3 dargestellten Ausführungsbeispiel besteht die Möglichkeit, die Wirkung des mit der Welle 1 verbundenen Gegengewichtes auf Schleifteller und Schleifblätter unterschiedlicher Masse einzustellen, so daß in jedem Fall ein vibrationsfreier Lauf der Handschleifmaschine gewähdeistet ist.In the embodiment shown in FIGS. 1 to 3, there is the possibility of adjusting the effect of the counterweight connected to the shaft 1 on sanding plates and sanding sheets of different masses, so that vibration-free running of the hand sanding machine is ensured in any case.

Zu diesem Zweck besteht das mit Welle 1 verbundene Gegengewicht nicht nur aus dem Abschnitt 21 mit vergrößertem Durchmesser, sondern umfaßt zusätzlich zwei verstellbare Körper in Form von Stellringen 31, 32, die eine kreisrunde Kontur und eine exzentrische Bohrung aufweisen. Diese Stellringe 31, 32 sind auf dem mittleren, zylindrischen Abschnitt der Welle 1 axial hintereinander angeordnet. Wegen ihrer exzentrischen Bohrung haben sie jeweilseinen in bezug auf die Achse 5 der Welle 1 exzentrischen Massenschwerpunkt, dessen Lage durch Drehen der Stellringe 31, 32 auf einer zur Wellenachse 5 konzentrischen Kreisbahn bewegbar ist. Die beiden Stellringe 31, 32 sind mittels sie radial durchsetzender Stellschrauben 33, 34 in einer beliebigen Winkelstellung zur Welle 1 und damit auch zu der die Wellenachse 5, die Achse 6 des Schleiftellers 7 und auch die Achse 22 des exzentrischen Ansatzes 21 verbindenden Symmetrieachse 23 verstellbar. Um die Stellung der beiden Stellringe 31, 32 bestimmen zu können, sind sie an ihrem Umfang mit einer Gradeinteilung 35, 36 versehen, der eine Strich marke 37 am Umfang der Welle 1 sowie eine Strichmarke 38 an der Oberseite des exzentrischen Abschnittes 21 gegenübersteht. Diese Marken 37,38 iiegen in der durch die Symmetrieachse 23 und die Wellenachse 5 definerten Ebene.For this purpose, the counterweight connected to shaft 1 does not only consist of section 21 with an enlarged diameter, but additionally comprises two adjustable bodies in the form of actuators rings 31, 32, which have a circular contour and an eccentric bore. These adjusting rings 31, 32 are arranged axially one behind the other on the central, cylindrical section of the shaft 1. Because of their eccentric bore, they each have a center of gravity eccentric with respect to the axis 5 of the shaft 1, the position of which can be moved on a circular path concentric with the shaft axis 5 by rotating the adjusting rings 31, 32. The two adjusting rings 31, 32 can be adjusted by means of adjusting screws 33, 34 penetrating them radially in any angular position to the shaft 1 and thus also to the axis of symmetry 23 connecting the shaft axis 5, the axis 6 of the grinding plate 7 and also the axis 22 of the eccentric extension 21 . In order to be able to determine the position of the two adjusting rings 31, 32, they are provided on their circumference with a graduation 35, 36, which is opposite a line mark 37 on the circumference of the shaft 1 and a line mark 38 on the top of the eccentric section 21. These marks 37, 38 lie in the plane defined by the axis of symmetry 23 and the shaft axis 5.

Wie oben erwähnt, ist die von einer exzentrischen Masse ausgeübte Radialkraft von der Masse m des exzentrischen Körpers, dem Abstand r des Massenschwerpunktes von der Drehachse und der Drehzahl abhängig. Drückt man in üblicher Weise die Drehzahl durch die Winkelgeschwindigkeit ω aus, ergibt sich für die Radialkraft K = m.r.ω2. Da die Winkelgeschwindigkeit m bei laufender Handschleifmaschine für alle von der Welle 1 angetriebenen Teile gleich groß ist, kann sie außer Betracht bleiben. Demgemäß ist die von einem der Stellringe 31 und 32 ausgeübte Radialkraft, gleiche Ausbildung der Stellringe vorausgesetzt, dem Produkt mr proportional. Werden die beiden Stellringe so eingestellt, daß ihre Schwerpunkte symmetrisch zur Symmetrieachse 23 liegen und mit der Symmetrieachse jeweils einen Winkel |α| einschließen, so ist die resultierende Radialkraft der Faktor K = 2mr.cos.a proportinal (siehe Fig. 4). Dabei ist von Interesse, daß für Winkel |α| kleiner als 90° die K proportionale Radialkraft zu der Radialkraft addiert wird, die sich aus der Masse mo und dem Abstand ro von der Wellenachse 5 des Massenschwerpunktes des exzentrischen Abschnittes 21 ergibt. Werden jedoch die Stellringe 31, 32 in eine Lage gebracht, bei der |α|größer ist als 90°, ist die Resultierende K der beiden Komponenten mr zu der von dem exzentrischen Abschnitt 21 ausgeübten Radialkraft entgegengesetzt gerichtet, so daß diese Radialkraft vermindert wird. Damit können durch einfaches Verdrehen der Stellringe 31, 32 sowohl Anordnungen kompensiert werden, deren Unwucht größer ist als die allein durch den exzentrischen Abschnitt 21 kompensierte Unwucht, als auch Unwuchten, die kleiner sind als dieser Wert. Damit ergibt sich ein weiter, in Fig. 5 dargestellter Variationsbereich von moro-2mr bis moro + 2mr. Dabei ist von besonderem Vorteil, daß mit Hilfe der stetig verdrehbaren Stellringe auf sehr einfache Weise eine sehr genaue Kompensation jeder innerhalb des genannten Bereiche liegenden Unwucht möglich ist. Die am Umfang der Stellringe 31, 32 angebrachten Skalen 35, 36 enthalten Angaben über die Stellungen, die bestimmten Schleiftellern undloder Schleifblättern zugeordnet sind. Weiterhin erleichtern die Skalen eine genau symmetrische Einstellung der Stellringe in Bezug auf die Symmetrieachse 23.As mentioned above, the radial force exerted by an eccentric mass depends on the mass m of the eccentric body, the distance r of the center of gravity from the axis of rotation and the speed. If the speed is expressed in the usual way by the angular velocity ω, the radial force is K = mrω 2 . Since the angular velocity m is the same for all parts driven by the shaft 1 when the hand grinder is running, it can be disregarded. Accordingly, the radial force exerted by one of the adjusting rings 31 and 32, provided the adjusting rings are of the same design, is proportional to the product mr. If the two adjusting rings are set so that their centers of gravity are symmetrical about the axis of symmetry 23 and an angle | α | with the axis of symmetry include, the resulting radial force is the factor K = 2mr.cos.a proportinal (see Fig. 4). It is of interest here that for angles | α | less than 90 °, the K proportional radial force is added to the radial force which results from the mass m o and the distance r o from the shaft axis 5 of the center of mass of the eccentric section 21. However, if the adjusting rings 31, 32 are brought into a position in which | α | is greater than 90 °, the resultant K of the two components mr is directed opposite to the radial force exerted by the eccentric section 21, so that this radial force is reduced. Thus, by simply turning the adjusting rings 31, 32, arrangements can be compensated for whose unbalance is greater than the unbalance compensated solely by the eccentric section 21, as well as unbalances that are smaller than this value. This results in a further variation range, shown in FIG. 5, from m o r o -2mr to m o r o + 2mr. It is particularly advantageous that with the aid of the continuously rotatable adjusting rings, very precise compensation of any imbalance within the ranges mentioned is possible in a very simple manner. The scales 35, 36 attached to the circumference of the adjusting rings 31, 32 contain information about the positions which are assigned to certain grinding plates and / or grinding sheets. Furthermore, the scales facilitate a precisely symmetrical setting of the adjusting rings with respect to the axis of symmetry 23.

Bei der in Fig. 6 dargestellten Ausführungsform der Erfindung finden als verstellbare Körper 41, 42 anstatt auf der Welle verdrehbarer, exzentrischer Stellringe an der Umfangsfläche der Welle 51 befestigte Körper Verwendung, die an ihrem der Welle 51 zugewandten Ende nicht näher dargestellte Gewindezapfen aufweisen, mit denen sie in entsprechende Gewindebohrungen 43, 44 eingedreht sind, die auf den Umfang der Welle 51 verteilt sind. Dabei habendie Körper41,42 eine derart unterschiedliche Masse, daß ein Versetzen der kleineren Körper 42 über den gesamten Variationsbereich von annähernd 180° einem Versetzen der größeren Körper 41 von einer Position zur anderen entspricht, so daß durch die Wahl der Stellung beider Körper ein sehr feiner Abgleich möglich ist, obwohl diese Körper nur um diskrete Beträge versetzt werden können. Dabei kann die Anordnung auch so getroffen sein, daß die Gewindebohrungen 43 für die größeren Körper 41 unterschiedlichen Schleiftellern zugeordnet sind, wogegen die kleineren Körper 42 dazu dienen können, die durch die Verwendung unterschiedlicher Schleifblätter bedingten Unwuchten auszugleichen. Die Gewindebohrungen 43, 44 sind mit Markierungen 45, 46 in Form von Ziffern, Buchstaben und sonstigen Symbolen bezeichnet, die eine Zuordnung der jeweiligen Stellung der einschraubbaren Körper 41, 42 zu bestimmten Schleiftellern und/oder Schleifblätten erlauben.In the embodiment of the invention shown in FIG. 6, the bodies 41, 42 used instead of eccentric adjusting rings which can be rotated on the shaft are bodies which are fastened to the peripheral surface of the shaft 51 and which have threaded pins, not shown, on their end facing the shaft 51 which they are screwed into corresponding threaded bores 43, 44 which are distributed over the circumference of the shaft 51. The bodies 41, 42 have such a different mass that moving the smaller bodies 42 over the entire range of variation of approximately 180 ° corresponds to moving the larger bodies 41 from one position to another, so that the choice of the position of both bodies makes them very fine Matching is possible, although these bodies can only be moved by discrete amounts. The arrangement can also be such that the threaded bores 43 for the larger bodies 41 are assigned to different grinding plates, whereas the smaller bodies 42 can serve to compensate for the imbalances caused by the use of different grinding sheets. The threaded bores 43, 44 are designated with markings 45, 46 in the form of numbers, letters and other symbols which allow the respective position of the screw-in bodies 41, 42 to be assigned to specific grinding plates and / or grinding wheels.

Fig. 6 zeigt die Welle 51 und den Schleifteller 52 in einer zur Symmetrieachse 23 nach Fig. 4 senkrechten Blickrichtung, ähnlich dem Schnitt nach Fig. 1, so daß nur die zu einer Seite der in der Zeichnungsebene liegenden Symmetrieachse angeordneten Körper 41, 42 sichtbar sind. Es versteht sich daher, daß die gleiche Anordnung von Körpern 41,42 an der in Flg, 6 nicht sichtbaren Rückseite der Welle 51 vorhanden ist und dafür Sorge getragen werden muß, daß die jeweils paarweise vorhandenen Körper 41 bzw. 42 zu der genannten Symmetrieachse symmetrisch angeordnet werden.6 shows the shaft 51 and the grinding plate 52 in a viewing direction perpendicular to the axis of symmetry 23 according to FIG. 4, similar to the section according to FIG. 1, so that only the bodies 41, 42 arranged on one side of the axis of symmetry in the plane of the drawing are visible are. It is therefore understood that the same arrangement of bodies 41, 42 is present on the rear side of the shaft 51, which is not visible in FIGS. 6 and 6, and care must be taken to ensure that the bodies 41 and 42, which are present in pairs, are symmetrical about the axis of symmetry mentioned to be ordered.

Die Erfindung ist nicht auf die dargestellten Ausführungsbeispiele beschränkt, sondern es sind Abweichungen davon möglich sind, ohne den Rahmen der Erfindung zu verlassen. Es ist ohne weiteres ersichtlich, daß es sehr viele Möglichkeiten gibt, die gegenüber einer Welle verstellbaren Körper in solcontour and an eccentric bore.The invention is not limited to the exemplary embodiments shown, but deviations from it are possible without leaving the scope of the invention. It is readily apparent that there are a great many possibilities in sol contour and an eccentric bore.

6. A hand grinder according to one of the preceding Claims, characterised in that the adjustable bodies (31, 32 ; 41, 42) and/or the shaft (1, 21) are provided with markings (35, 36, 37, 38; 41, 46) associated with selected positions of the bodies.6. A hand grinder according to one of the preceding claims, characterized in that the adjustable bodies (31, 32; 41, 42) and / or the shaft (1, 21) are provided with markings (35, 36, 37, 38 ; 41, 46) associated with selected positions of the bodies.

7. A hand grinder according to one of the preceding Claims, characterised in that the shaft (1) has at one end a central screw-threaded bore (2) to receive the threaded joumal of a motor shaft (3) and has atthe other end an eccentric recess (4) in which there is disposed a bearing arrangementforthe grinding plate (7) and, at the end adjacent the grinding plate (7), an eccentric portion (21) of enlarged diameter which, in relation to the axis (5) of the shaft (1), is directed in opposition to the eccentric bearing for the grinding plate (7) and in that the adjustable bodies (31, 32) are disposed on the portion of the shaft (1) adjacent the eccentric portion (21).7. A hand grinder according to one of the preceding Claims, characterized in that the shaft (1) has at one end a central screw-threaded bore (2) to receive the threaded joumal of a motor shaft (3) and has atthe other end an eccentric recess (4) in which there is disposed a bearing arrangementforthe grinding plate (7) and, at the end adjacent the grinding plate (7), an eccentric portion (21) of enlarged diameter which, in relation to the axis ( 5) of the shaft (1), is directed in opposition to the eccentric bearing for the grinding plate (7) and in that the adjustable bodies (31, 32) are disposed on the portion of the shaft (1) adjacent the eccentric portion (21).

Claims (7)

1.
EP88112981A 1987-08-18 1988-08-10 Portable sander Expired - Lifetime EP0303955B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88112981T ATE63710T1 (en) 1987-08-18 1988-08-10 HAND GRINDER.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3727487 1987-08-18
DE19873727487 DE3727487A1 (en) 1987-08-18 1987-08-18 HAND GRINDING MACHINE

Publications (2)

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EP0303955A1 EP0303955A1 (en) 1989-02-22
EP0303955B1 true EP0303955B1 (en) 1991-05-22

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ID=6333968

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EP (1) EP0303955B1 (en)
JP (1) JPH01135460A (en)
AT (1) ATE63710T1 (en)
AU (1) AU596026B2 (en)
BR (1) BR8804195A (en)
CA (1) CA1313309C (en)
DD (1) DD282194A5 (en)
DE (2) DE3727487A1 (en)
DK (1) DK459888A (en)
ES (1) ES2022553B3 (en)
GR (1) GR3002603T3 (en)
NO (1) NO883661L (en)
RU (1) RU1834788C (en)

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DE3942301C1 (en) * 1989-12-21 1991-02-14 Robert Bosch Gmbh, 7000 Stuttgart, De
JP3236169B2 (en) * 1994-08-01 2001-12-10 株式会社リコー Fixing device
US6206771B1 (en) * 1999-01-25 2001-03-27 Dynabrade, Inc. Balancer for orbital abrading machine
US7022002B2 (en) 2004-03-03 2006-04-04 Dynabrade, Inc. Modular counterweight apparatus for an orbital abrading machine
DE102007018466A1 (en) * 2007-04-19 2008-10-23 Robert Bosch Gmbh Motor driven machine tool
DE102007062560A1 (en) * 2007-12-22 2009-06-25 J. Wagner Gmbh surface grinding machine
EP2127808A1 (en) * 2008-05-29 2009-12-02 Black & Decker, Inc. Power tool
CN104096671B (en) * 2014-08-01 2016-06-15 吉首大学 Convenient adjustable Link-Belt PD device
CN107457690B (en) * 2017-08-31 2018-06-29 广州市永合祥自动化设备科技有限公司 Polisher lapper and its auxiliary body
CN113601359B (en) * 2021-08-30 2022-10-21 中电鹏程智能装备有限公司 Automatic flexible automatic grinding device of centre gripping formula of abrasive paper

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US3482362A (en) * 1966-01-28 1969-12-09 Ingersoll Rand Co Double acting sander head
DE1752453A1 (en) * 1968-05-29 1971-05-19 Miller Sanuel A Portable polishing machine
DE2745129A1 (en) * 1977-10-07 1979-04-12 Miksa Marton RANDOM HEAD FOR A HAND GRINDING MACHINE
DE3517766A1 (en) * 1984-09-08 1986-03-20 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt ORBITAL GRINDERS
DE8711895U1 (en) * 1987-08-18 1987-10-15 Marton, Miksa, Windsor, Ontario Hand grinder

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GR3002603T3 (en) 1993-01-25
DK459888A (en) 1989-02-19
NO883661D0 (en) 1988-08-17
DK459888D0 (en) 1988-08-17
BR8804195A (en) 1989-03-14
DE3727487A1 (en) 1989-03-02
AU2112088A (en) 1989-02-23
DD282194A5 (en) 1990-09-05
ES2022553B3 (en) 1991-12-01
JPH01135460A (en) 1989-05-29
CA1313309C (en) 1993-02-02
DE3727487C2 (en) 1989-05-24
RU1834788C (en) 1993-08-15
DE3862909D1 (en) 1991-06-27
AU596026B2 (en) 1990-04-12
EP0303955A1 (en) 1989-02-22
NO883661L (en) 1989-02-20
ATE63710T1 (en) 1991-06-15

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