EP0324357B1 - Device for clamping a disc-like tool - Google Patents

Device for clamping a disc-like tool Download PDF

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Publication number
EP0324357B1
EP0324357B1 EP89100067A EP89100067A EP0324357B1 EP 0324357 B1 EP0324357 B1 EP 0324357B1 EP 89100067 A EP89100067 A EP 89100067A EP 89100067 A EP89100067 A EP 89100067A EP 0324357 B1 EP0324357 B1 EP 0324357B1
Authority
EP
European Patent Office
Prior art keywords
clamping
tool
machine according
tool spindle
flange
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP89100067A
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German (de)
French (fr)
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EP0324357A3 (en
EP0324357A2 (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
C&E Fein GmbH and Co
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C&E Fein GmbH and Co
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Filing date
Publication date
Application filed by C&E Fein GmbH and Co filed Critical C&E Fein GmbH and Co
Publication of EP0324357A2 publication Critical patent/EP0324357A2/en
Publication of EP0324357A3 publication Critical patent/EP0324357A3/en
Application granted granted Critical
Publication of EP0324357B1 publication Critical patent/EP0324357B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B45/00—Means for securing grinding wheels on rotary arbors
    • B24B45/006—Quick mount and release means for disc-like wheels, e.g. on power tools
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T83/00—Cutting
    • Y10T83/929—Tool or tool with support
    • Y10T83/9372—Rotatable type
    • Y10T83/9377—Mounting of tool about rod-type shaft
    • Y10T83/9379—At end of shaft

Definitions

  • the invention relates to a hand-held machine tool with a device for clamping a disk-shaped tool on a motor-driven rotating tool spindle, in particular for clamping a grinding wheel on an angle grinder, with a clamping anchor arranged in the tool spindle, which is provided with an axial recess, and can be displaced axially relative to it and connected to it in a rotationally fixed manner , with a clamping flange that can be detachably attached to the free end of the clamping anchor, with an abutment arranged on the tool-side end of the tool spindle and with a device that can be actuated by means of a manual actuation mechanism for releasably pressing the clamping flange against the abutment with intermediate clamping of the tool.
  • Such a device is known from DE-PS 34 05 855.
  • the clamping anchor arranged in the tool spindle designed as a hollow spindle is displaced by a compression spring also arranged in the tool spindle in such a way that a clamping flange which can be fastened to the clamping anchor clamps the disk-shaped tool against an abutment on the tool spindle.
  • the clamping force is generated by a spring arranged in the hollow spindle.
  • the tensioning of the tensioning anchor by means of the known spring requires a manual actuation mechanism which is fixed to the housing on the opposite side of the tool and which allows a force which counteracts the spring to be applied manually, so that this type of actuation prevents the most compact construction of the entire device.
  • the invention is therefore based on the object of making the known device for fastening a disk-shaped grinding tool, in which no auxiliary tool is required for loosening or tightening the tool fastening, as compact as possible, in particular hydraulically actuable. Reliable clamping should also be ensured in those cases in which changing torques act on the tool spindle.
  • the device has a first pressure cylinder, comprising a first cavity between the clamping anchor and the tool spindle, and a second Pressure cylinder, comprising a second cavity arranged in the clamping anchor or in the tool spindle and a connecting channel between the two cavities, that the second pressure cylinder comprises a piston arranged in the second cavity, which is adjustable for clamping from a tool-side end of the tool spindle by the manual actuation mechanism and in its position exciting the tool can be determined that the manual operating mechanism has a holding device which can be releasably attached to the tension anchor, which can be operated manually for pressing the clamping flange against the abutment, and that the holding device can be fixed in a rotationally fixed manner on the tool spindle.
  • a clamping device for clamping a tool arranged on a machine part by interaction of a first and a second pressure cylinder and an actuating device is known.
  • this clamping device is always arranged so that the tool between it itself and the machine part, that is, for example the tool spindle, is arranged so that the entire clamping device is arranged opposite the tool of the tool spindle and sits directly on the tool and consequently this against the Tool spindle can press.
  • the DE-U 69 18 532 can not anticipate the special design of the tool spindle and the tension anchor guided therein, as well as the arrangement and the two pressure cylinders within the tool spindle provided with an axial recess, as is the subject of the present invention.
  • a hydraulic clamping device for clamping a tool on a stationary machine tool has also become known.
  • the tool is hydraulically clamped between a fixed machine-side abutment and a clamping flange, which is screwed onto the outer free end of a central piston of the clamping device.
  • the actual clamping process is carried out by tightening a central clamping screw on the outer free end of the piston, whereby a hydraulic pressure is generated in a pressure chamber behind it, which is transmitted via a connecting channel to an annular chamber between the piston and the stationary abutment.
  • the tool is hydraulically clamped against the fixed abutment via the clamping flange.
  • GB-A 2 074 056 also does not anticipate or suggest the design of the hand-held power tool according to the invention, since the known clamping device relates to a machine tool of another type which does not have a manual operating mechanism.
  • both pressure cylinders are arranged in the tool spindle, which is necessary anyway, and can also be actuated from an end of the tool spindle on the tool side, the two pressure cylinders being correspondingly connected to one another both in the position that clamps the tool and in the position that does not clamp the tool, and during clamping the actuatable piston of the second pressure cylinder acts on a pressure medium arranged in both pressure cylinders and in the connecting channel, which in turn then causes in the second pressure cylinder that the tension anchor moves from its position not exciting the tool into its position exciting the tool.
  • the manual actuation mechanism has a holding device which can be fastened to the clamping anchor and can be pressed against the abutment, which can be locked in a form-fitting manner on the tool spindle.
  • first cavity is defined by mutually facing and axially spaced boundary surfaces of the tool spindle and the tension anchor and corresponding lateral surfaces of the tension anchor and the tool spindle.
  • a structurally particularly simple solution can be achieved in that the boundary surface of the tension anchor faces the tool, while the boundary surface of the tool spindle is arranged facing away from the tool, so that a volume dilation in the first cavity leads to the boundary surface of the tension anchor facing away from the tool is moved and thus the Anchors can perform an axial displacement directly exciting the tool.
  • the manual control device according to the invention can be integrated particularly well into a hand-held power tool if the manual control device comprises an adjustable clamping element which acts on the piston for clamping.
  • the tendon can be directly loaded with the hand and locked in its actuated position. Easier and, above all, less forceful operability of the tendon is possible if it has a surface that is oriented obliquely to an adjustment direction of the piston.
  • This surface can be, for example, the lateral surface of an eccentric, via which the piston can be actuated, for example, by means of a piston rod.
  • the inclined surface can also be a run-up surface which can be displaced transversely to the direction of adjustment of the piston and which also acts, for example, on a piston rod and thereby displaces the piston.
  • the simplest possibility of realizing the inclined surface is when the tendon has a thread, the threaded surfaces of which then form the inclined surfaces.
  • the tendon itself can be arranged at different points within the scope of the manual control device.
  • the tendon is arranged in the tension anchor or in the tool spindle, in particular in the bore extending up to the piston.
  • the holding device comprises the clamping flange.
  • the holding device has a holding member which can be positively fastened to the tensioning anchor against axial displacement and which, together with the tensioning flange, can be fixed in a rotationally fixed manner to the tool spindle by form-locking elements.
  • the holding member can be designed in a wide variety of ways. It is possible, for example, if the holding member can be connected to the tension anchor in the form of a bayonet catch.
  • a constructive alternative to this provides that the holding member can be screwed into the tension anchor.
  • a particularly preferred embodiment of a manual actuation mechanism provides that the tensioning member and the holding member are the same screw, so that by screwing this screw into the tensioning anchor both the tensioning flange is fastened to the same and the piston is simultaneously actuated.
  • the screw can be screwed into a first and an adjoining second threaded section of the tension anchor and if the piston can be actuated when screwing into the second threaded section.
  • Such a constructive solution has the great advantage that first of all a rough securing of the clamping flange on the clamping anchor can take place and, when the screw is screwed in further, the piston is actuated, which then leads to the final clamping of the tool.
  • the clamping flange is rotatably held on the holding member and can be acted upon by it in the direction of the tool. This is necessary in order to avoid, when fastening the tool, that the rotation of the holding member is made difficult by frictional forces between the tool and the screw itself.
  • the holding member can still be designed so that it can be easily rotated with respect to the clamping flange, even if, for example, a shoulder is applied to the clamping flange.
  • a particularly easy turning of the holding member can be achieved if an axial pressure bearing is arranged between the screw and the clamping flange.
  • a form-fitting securing of the holding member can be achieved, for example, by providing a detent that can be displaced in the radial direction of the tool spindle.
  • the tendon can be secured by a locking element which can be displaced in the axial direction, which can be, for example, a bolt which engages in bores in both the tendon and the tensioning flange.
  • the securing element is held in a rotationally fixed and axially displaceable manner on the tensioning member or on the tensioning flange and can be brought into engagement with a toothed ring of the tensioning flange or tensioning member which is coaxial with its axis of rotation. It is thus possible to secure the tendon at an angular position corresponding to an angular distance between successive teeth of the ring gear.
  • the securing element can be locked in its position securing the screw.
  • the first and second cavities and the connecting channel are filled with a plastic mass for hydraulic pressure transmission.
  • a plastic mass for hydraulic pressure transmission. This is particularly expedient because handheld power tools are to be used when there are large temperature differences and these are then to function reliably. When using a conventional hydraulic oil, this leads to sealing problems in the pressure cylinders that are difficult or almost impossible to control.
  • the plastic mass has the advantage that this type of tightness problem can be avoided.
  • a particularly preferred plastic mass is a polyvinyl chloride with a relatively low degree of polymerization.
  • the first cavity, the second cavity and the connecting channel can be filled with a viscous mass, since the above-mentioned tightness problems can also be avoided with this.
  • the viscous mass is preferably a silicone mass, in particular a silicone lubricant.
  • plastic or viscous masses are compressible, since these then become elastic and different The dimensions of the individual parts lead to the tension of the tool being adjusted.
  • an elastic element allowing an axial displacement of the clamping flange is provided relative to the tool spindle.
  • This element can be arranged in a wide variety of locations. For example, it is conceivable to arrange this element between the clamping flange and the holding member acting on it.
  • This elastic element is preferably dimensioned such that it can be compressed to inelasticity when the tool is clamped. This enables an even greater distance to be reached when clamping and that this elastic element also ensures that if the tool according to the invention has not been completely clamped, it ensures that the tool nevertheless rotates with the tool spindle and thus not to all possible accidents caused by insufficient tension.
  • the elastic element is a volume-elastic element arranged in one of the cavities, so that it is first compressed and then the tool is finally clamped by the volume compression.
  • a first exemplary embodiment of an angle grinding machine according to the invention shown in FIG. 1, comprises a drive motor 10, partially shown in the drawing, the drive shaft 12 of which drives a bevel gear 16 of a tool spindle 20 rotatably mounted in a gear housing 18 via a drive pinion 14.
  • This tool spindle 20 has at one end a flange 24 serving as an abutment for a tool, in particular a grinding wheel 22.
  • the tool spindle 20 is mounted in the gear housing 18 on a side facing the flange 24 by means of a lower bearing 26 and on a side facing away from the flange 24 by means of an upper bearing 28 arranged at a distance from the lower bearing 26.
  • the tool spindle 20 is one Axis 30 rotatable.
  • the tool spindle 20 which is designed as a hollow spindle, comprises a coaxial central recess 32 which, with a widened section 36, extends into the tool spindle 20 from an end 34 opposite the flange 24 and thus the tool 22, via a step surface 38 into a central section 40 passes into a smaller diameter with respect to the widened section 36 and, following the central section 40, widens in the region of the flange 24 to form a toothed section 44 which is provided with internal teeth 42 and which is open towards the tool 22.
  • a tension anchor 46 is displaceable in the axial direction, but is mounted in a rotationally fixed manner, which has a center piece 48 guided in the central section 40 of the coaxial recess 32, which carries on its end facing away from the tool 22 a tension anchor head 50 which has a larger diameter than the middle piece 48 and is guided in the expanded section 36.
  • this tension anchor head 50 On its side facing the step surface 38, this tension anchor head 50 has an annular surface 54 which extends up to a lateral surface 52 of the central piece 48, which together with the lateral surface 52 of the central piece 48, the step surface 38 and the widened section 36 of the coaxial recess 32 has a first Cavity 56 of a first pressure cylinder, formed by the tool spindle 20 and the clamping anchor 46 displaceable therein, is limited.
  • the middle piece 48 is provided with an annular seal 58 which is effective with respect to the central section 40 of the coaxial recess
  • the tension anchor head 50 is provided with an annular seal 60 which is effective with respect to the expanded section 36.
  • the tension anchor 46 is in turn also provided with a central bore 62 penetrating it from the side of the tension anchor head 50, into which a screw plug 64 is screwed in the area of the tension anchor head 50.
  • a central bore 62 penetrating it from the side of the tension anchor head 50, into which a screw plug 64 is screwed in the area of the tension anchor head 50.
  • connecting channels 66 extending in the radial direction and arranged in a region of the central piece 48 facing the tension anchor head 50 extend to the first cavity 56.
  • a piston 68 is sealingly arranged in the central bore 62 and defines a second cavity 70 which is delimited on the one hand by the piston 68, on the other hand by the screw plug 64 and by a bore section 72 of the central bore 62 lying between the two .
  • the piston 68 itself is acted upon from its side facing the tool 22 by a piston rod 74 which extends away from the piston 68 through the central bore 62 in the direction of the tool 22.
  • the tension anchor 46 is provided with a threaded bore 76 into which the central bore 62 originating from the tension anchor head 50 merges, the threaded bore 76 has a larger diameter than the central bore 62.
  • the piston rod 74 is dimensioned such that it projects out of the central bore 62 into a second threaded section 78 of the threaded bore 76, which adjoins the central bore 62.
  • This second threaded section 78 is followed in the axial direction towards the tool 22 by a first threaded section 80 of the threaded bore 76.
  • the tool that is to say the grinding wheel 22 in this case, is held by means of a clamping flange 82, which is part of a holding device designated as a whole by 84.
  • This holding device 84 comprises a holding screw 86 which can be screwed into the threaded bore 76 from the side of the tool 22 using a threaded bolt 88.
  • a cylindrical piece 90 Connected to this threaded bolt 88 of the holding device 84 is a cylindrical piece 90, which carries on its end opposite the threaded bolt 88 a circular disk-shaped screw head 92 which extends essentially parallel to the flange 24 and has a diameter approximately comparable to this.
  • This screw head 92 acts on the clamping flange 82 via an axial pressure bearing 94 arranged on its side facing the flange 24, which clamps the grinding wheel 22 between it and the flange 24 designed as an abutment in order to hold the grinding wheel 22.
  • a sleeve 96 which surrounds the cylindrical piece 90 and is rotatably mounted on the cylindrical piece 90, is formed on the clamping flange 82.
  • This sleeve 96 carries one External teeth 98, which can be brought into engagement with the internal teeth 42 of the toothed section 44 of the coaxial recess 32.
  • the sleeve 96 can thus be displaced in the axial direction into the toothed section 44, but is held non-rotatably in the latter relative to the tool spindle 20.
  • both the screw head 92 and the clamping flange 82 have the same diameter and both are provided with teeth 100 and 102 on their surfaces lying radially outside with respect to the axis 30, both teeth 100 and 102 with one another are identical.
  • the two toothings 100, 102 preferably have teeth arranged at an angular distance of approximately 5 °.
  • This cover cap 106 is mounted on the retaining screw 86 by means of a pin 108 in that this pin 108 engages in an inner bore 110 which extends from the end face 112 into the retaining screw 86.
  • the entire cover cap can be displaced in the direction of the axis 30 by the pin 108 guided in the inner bore 110, so that the inner toothed ring 104 either engages only with the toothing 100 of the screw head 92 or both with the toothing 100 of the screw head 92 as as well as with the toothing 102 of the clamping flange 82.
  • the pin 108 is provided with a first annular groove 114 into which a retaining ring 118 mounted in a circumferential groove 116 of the inner bore 110 engages when both toothings 100 and 102 are engaged with the internal ring gear 104.
  • the pin 108 is additionally provided with a second annular groove 120, into which the retaining ring 118 engages when the internal ring gear 104 is only engaged with the toothing 100.
  • FIG. 1 The exemplary embodiment according to the invention shown in FIG. 1 now functions as follows:
  • the entire holding device 84 is removed by unscrewing the threaded bolt 88 from the threaded bore 76.
  • a new grinding wheel 22 can now be placed on the flange 24.
  • the holding device 84 is inserted, the sleeve 96 integrally formed on the clamping flange 82 being rotated such that its external toothing 98 comes into engagement with the internal toothing 42 of the toothed section 44 of the coaxial recess 32.
  • This sleeve 96 thus ensures that the clamping flange 82 is non-rotatably connected to the tool spindle 20.
  • the retaining screw 86 is then screwed with its threaded bolt 88 into the threaded bore 76 of the tensioning anchor 46 with the cover cap only engaged with the toothing 100, whereby the threaded bolt 88 first turns into the first threaded section 80 and then reaches the adjoining second threaded section 78.
  • the clamping anchor 46 is pulled in the direction of the tool 22 until the movement of the clamping anchor 46 itself and the displacement of Pressure transmission medium from the first cavity 56 into the second cavity 70 via the piston 68 which have brought the piston rod 74 into contact with the front surface 122.
  • the reverse process takes place when the front surface 122 abuts the piston rod 74 before the clamping flange 82 contacts the grinding wheel 22 on the flange 24.
  • the threaded bolt 88 pulls the entire tension anchor 46 in the direction of the flange 24 by engaging in the threaded bore 76, so that the first cavity 56 of the first pressure cylinder is reduced, since the annular surface 54 and the step surface 38 towards each other be moved.
  • the front surface 122 presses the piston 68 in the direction of the tension anchor head 50 via the piston rod 74, so that the second cavity 70 is also reduced.
  • the first cavity 56, the second cavity 70 and also the connecting channels 66 are filled with a plastic mass, preferably a polyvinyl chloride with a relatively low degree of polymerization.
  • This plastic mass is pressurized by the reduction in the first cavity 56 and the simultaneous reduction in the second cavity 70 when the retaining screw 86 is screwed in, so that this plastic mass tends to move the tension anchor 46 as a whole away from the flange 44, and thereby exerts an additional axial tensile force on the retaining screw 86 so that it presses the grinding wheel 22 firmly against the flange 24 via the thrust bearing 94 and the clamping flange 82 and thus clamps the grinding wheel with the necessary force between the clamping flange 82 and the flange 24.
  • the advantageous effect of the two pressure cylinders working together can be seen in the fact that when the threaded bolt 88 begins to act on the piston rod 74 with its front surface 122, a slight rotation of the retaining screw 86 reduces both the first cavity 56 and the second cavity 70 and thus prestresses the plastic mass with high forces, the transmission ratio between the action of the piston 68 with a small piston area and the circular ring surfaces 54 and 38 acting as large piston areas also being effective.
  • the plastic mass has a certain elasticity and thus serves as a volume-compressible elastic element, which allows the grinding wheel 22 to be held tensioned when the retaining screw 86 is turned on.
  • the cover cap 106 is moved so far in the axial direction after tightening that the internal ring gear 104 also comes into engagement with the toothing 102, so that the screw head 92 can no longer rotate relative to the clamping flange 82, the latter for its part is held on the external toothing 98, which is in engagement with the internal toothing 42 of the tool spindle 20, so that no turning of the screw head 92 relative to the tool spindle 20 is possible.
  • a piston ring 130 is provided at a distance from the step surface 38 and extends between the widened section 36 of the coaxial recess 32 and the outer surface 52 of the center piece 48, which seals between these two surfaces and is sealed by means of disc springs 132 is supported on the step surface 38.
  • the first cavity 56 'of the second embodiment is therefore not limited by the step surface 38, but by a piston ring surface 134 facing the annular surface 54.
  • the plate springs 132 have the task of acting as an additional elastic element when tightening the retaining screw 86, so that when the threaded bolt 88 acts on the piston surface 74 with its front surface 122, further rotation is possible by a considerable angle, since the tightening of the Retaining screw 86 is not limited by the elasticity of the plastic mass, but first the disk springs 132 are compressed when the screw is turned further until the piston ring 130 is supported by the stepped surface 38 via the compressed disk springs 132. Only then is there a slight compression of the plastic mass arranged in the first cavity 56 ', the second cavity 70 and the connecting channels 66 in order to achieve a final tensioning of the grinding wheel 22.
  • the thrust bearing 94 is sealed against contamination by a felt ring 95 surrounding it.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)

Description

Die Erfindung betrifft eine Handwerkzeugmaschine mit einer Einrichtung zum Spannen eines scheibenförmigen Werkzeugs an einer motorisch rotierend angetriebenen Werkzeugspindel, insbesondere zum Spannen einer Schleifscheibe an einer Winkelschleifmaschine, mit einem in der mit einer axialen Ausnehmung versehenen Werkzeugspindel angeordneten axial gegenüber dieser verschiebbaren und mit dieser drehfest verbundenen Spannanker, mit einem am freien Ende des Spannankers lösbar befestigbaren Spannflansch, mit einem am werkzeugseitigen Ende der Werkzeugspindel angeordneten Widerlager und mit einer mittels eines Handbetätigungsmechanismus betätigbaren Vorrichtung zum lösbaren Andrücken des Spannflansches gegen das Widerlager unter Zwischenklemmen des Werkzeugs.The invention relates to a hand-held machine tool with a device for clamping a disk-shaped tool on a motor-driven rotating tool spindle, in particular for clamping a grinding wheel on an angle grinder, with a clamping anchor arranged in the tool spindle, which is provided with an axial recess, and can be displaced axially relative to it and connected to it in a rotationally fixed manner , with a clamping flange that can be detachably attached to the free end of the clamping anchor, with an abutment arranged on the tool-side end of the tool spindle and with a device that can be actuated by means of a manual actuation mechanism for releasably pressing the clamping flange against the abutment with intermediate clamping of the tool.

Eine derartige Einrichtung ist aus der DE-PS 34 05 855 bekannt. Bei dieser wird der in der als Hohlspindel ausgebildeten Werkzeugspindel angeordnete Spannanker durch eine ebenfalls in der Werkzeugspindel angeordnete Druckfeder so verschoben, daS ein am Spannanker befestigbarer Spannflansch das scheibenförmige Werkzeug gegen ein Widerlager an der Werkzeugspindel spannt. Bei dieser Vorrichtung wird also die Spannkraft durch eine in der Hohlspindel angeordnete Feder erzeugt. Durch den Betätigungsmechanismus kann nun der Spannanker entgegen der Kraft der Druckfeder verschoben werden, so daß der Spannflansch von Hand leicht gelöst oder aufgeschraubt werden kann und folglich ein Befestigen des scheibenförmigen Werkzeugs ohne zusätzliche Werkzeuge möglich ist.Such a device is known from DE-PS 34 05 855. In this case, the clamping anchor arranged in the tool spindle designed as a hollow spindle is displaced by a compression spring also arranged in the tool spindle in such a way that a clamping flange which can be fastened to the clamping anchor clamps the disk-shaped tool against an abutment on the tool spindle. In this device, the clamping force is generated by a spring arranged in the hollow spindle. By means of the actuating mechanism, the tensioning anchor can now be moved against the force of the compression spring, so that the tensioning flange can be easily loosened or screwed on by hand and consequently the disk-shaped tool can be fastened without additional tools.

Das Spannen des Spannankers mittels der bekannten Feder erfordert einen auf der dem Werkzeug gegenüberliegenden Seite gehäusefest angeordneten Handbetätigungsmechanismus, welcher es erlaubt, eine der Feder entgegenwirkende Kraft manuell aufzubringen, so daß diese Betätigungsart einer möglichst kompakten Bauweise der gesamten Einrichtung entgegensteht.The tensioning of the tensioning anchor by means of the known spring requires a manual actuation mechanism which is fixed to the housing on the opposite side of the tool and which allows a force which counteracts the spring to be applied manually, so that this type of actuation prevents the most compact construction of the entire device.

Der Erfindung liegt daher die Aufgabe zugrunde, die bekannte Einrichtung zum Befestigen eines scheibenförmigen Schleifwerkzeugs, bei welchem man kein Hilfswerkzeug zum Lösen oder Anziehen der Werkzeugbefestigung benötigt, möglichst kompakt, insbesondere hydraulisch betätigbar zu gestalten. Dabei soll ein zuverlässiges Spannen auch in solchen Fällen gewährleistet sein, in denen auf die Werkzeugspindel wechselnde Drehmomente wirken.The invention is therefore based on the object of making the known device for fastening a disk-shaped grinding tool, in which no auxiliary tool is required for loosening or tightening the tool fastening, as compact as possible, in particular hydraulically actuable. Reliable clamping should also be ensured in those cases in which changing torques act on the tool spindle.

Diese Aufgabe wird bei einer Einrichtung der eingangs beschriebenen Art erfindungsgemäß dadurch gelöst, daß die Vorrichtung einen ersten Druckzylinder, umfassend einen ersten Hohlraum zwischen dem Spannanker und der Werkzeugspindel, einen zweiten Druckzylinder, umfassend einen im Spannanker oder in der Werkzeugspindel angeordneten zweiten Hohlraum sowie einen Verbindungskanal zwischen den beiden Hohlräumen aufweist, daß der zweite Druckzylinder einen im zweiten Hohlraum angeordneten Kolben umfaßt, der zum Spannen von einem werkzeugseitigen Ende der Werkzeugspindel her durch den Handbetätigungsmechanismus verstellbar und in seiner das Werkzeug spannenden Stellung festlegbar ist, daß der Handbetätigungsmechanismus eine am Spannanker lösbar befestigbare Halteeinrichtung aufweist, welche zum Anpressen des Spannflansches gegen das Widerlager manuell bedienbar ist, und daß die Halteeinrichtung formschlüssig an der Werkzeugspindel drehfest fixierbar ist.This object is achieved according to the invention in a device of the type described at the outset in that the device has a first pressure cylinder, comprising a first cavity between the clamping anchor and the tool spindle, and a second Pressure cylinder, comprising a second cavity arranged in the clamping anchor or in the tool spindle and a connecting channel between the two cavities, that the second pressure cylinder comprises a piston arranged in the second cavity, which is adjustable for clamping from a tool-side end of the tool spindle by the manual actuation mechanism and in its position exciting the tool can be determined that the manual operating mechanism has a holding device which can be releasably attached to the tension anchor, which can be operated manually for pressing the clamping flange against the abutment, and that the holding device can be fixed in a rotationally fixed manner on the tool spindle.

Aus der DE-U 69 18 532 ist zwar eine Spanneinrichtung zum Aufspannen eines an einem Maschinenteil angeordneten Werkzeugs durch Zusammenwirken eines ersten und eines zweiten Druckzylinders sowie einer Betätigungseinrichtung bekannt. Diese Spanneinrichtung ist jedoch stets so angeordnet, daß das Werkzeug zwischen dieser selbst und dem Maschinenteil, das heißt beispielsweise der Werkzeugspindel angeordnet ist, so daß die gesamte Spanneinrichtung bezüglich des Werkzeugs der Werkzeugspindel gegenüberliegend angeordnet ist und unmittelbar auf dem Werkzeug sitzt und folglich dieses gegen die Werkzeugspindel drücken kann.From DE-U 69 18 532 a clamping device for clamping a tool arranged on a machine part by interaction of a first and a second pressure cylinder and an actuating device is known. However, this clamping device is always arranged so that the tool between it itself and the machine part, that is, for example the tool spindle, is arranged so that the entire clamping device is arranged opposite the tool of the tool spindle and sits directly on the tool and consequently this against the Tool spindle can press.

Damit kann das DE-U 69 18 532 die besondere Ausbildung der Werkzeugspindel und des darin geführten Spannankers sowie die Anordnung und der beiden Druckzylinders innerhalb der mit einer axialen Ausnehmung versehenen ausgebildeten Werkzeugspindel, wie dies Gegenstand der vorliegenden Erfindung ist, nicht vorwegnehmen.Thus, the DE-U 69 18 532 can not anticipate the special design of the tool spindle and the tension anchor guided therein, as well as the arrangement and the two pressure cylinders within the tool spindle provided with an axial recess, as is the subject of the present invention.

Aus der GB-A 2 074 056 ist ferner eine hydraulische Spanneinrichtung zum Spannen eines Werkzeuges auf einer stationären Werkzeugmaschine bekannt geworden. Bei dieser vorbekannten Einrichtung wird das Werkzeug zwischen einen festen maschinenseitigen Widerlager und einem Spannflansch hydraulisch gespannt, welcher auf das äußere freie Ende eines zentralen Kolbens der Spanneinrichtung aufgeschraubt wird. Der eigentliche Spannvorgang erfolgt durch Anziehen einer zentralen Spannschraube am äußeren freien Ende des Kolbens, wodurch in einer dahinterliegenden Druckkamer ein Hydraulikdruck erzeugt wird, welcher über einen Verbindungskanal auf eine Ringkammer zwischen dem Kolben und dem stationären Widerlager übertragen wird. Dadurch wird das Werkzeug über den Spannflansch gegen das feste Widerlager hydraulisch gespannt.From GB-A 2 074 056 a hydraulic clamping device for clamping a tool on a stationary machine tool has also become known. In this known device, the tool is hydraulically clamped between a fixed machine-side abutment and a clamping flange, which is screwed onto the outer free end of a central piston of the clamping device. The actual clamping process is carried out by tightening a central clamping screw on the outer free end of the piston, whereby a hydraulic pressure is generated in a pressure chamber behind it, which is transmitted via a connecting channel to an annular chamber between the piston and the stationary abutment. As a result, the tool is hydraulically clamped against the fixed abutment via the clamping flange.

Auch durch die GB-A 2 074 056 wird die erfindungsgemäße Ausbildung der Handwerkzeugmaschine weder vorweggenommen noch nahegelegt, da die vorbekannte Spanneinrichtung eine Werkzeugmaschine anderer Gattung betrifft, welche keinen Handbetätigungsmechanismus aufweist.GB-A 2 074 056 also does not anticipate or suggest the design of the hand-held power tool according to the invention, since the known clamping device relates to a machine tool of another type which does not have a manual operating mechanism.

Bei der erfindungsgemäßen Handwerkzeugmaschine sind beide Druckzylinder in der ohnehin notwendigen Werkzeugspindel angeordnet und außerdem von einem werkzeugseitigen Ende der Werkzeugspindel her betätigbar, wobei die beiden Druckzylinder sowohl in der das Werkzeug spannenden als auch der das Werkzeug nicht spannenden Stellung miteinander korrespondierend in Verbindung stehen und beim Spannen der betätigbare Kolben des zweiten Druckzylinders ein in beiden Druckzylindern sowie im Verbindungskanal angeordnetes Druckmedium beaufschlagt, welches dann seinerseits im zweiten Druckzylinder bewirkt, daß der Spannanker sich von seiner das Werkzeug nicht spannenden in seine das Werkzeug spannende Stellung bewegt. Vorzugsweise ist zwischen dem zweiten und dem ersten Druckzylinder eine Untersetzung vorgesehen, d.h., daß eine geringere, auf den Kolben beim Betätigen wirkende Kraft im zweiten Druckzylinder zu einer größeren Kraft auf den Spannanker im ersten Druckzylinder führt. Um auch bei Beanspruchung der Werkzeugspndel durch wechselnde Drehmomente eine zuverlässige Spannung des Werkzeuges sicherzustellen, weist der Handbetätigungsmechanismus eine am Spannanker lösbare befestigbare Halteeinrichtung zum Anpressen des Spannflansches gegen das Widerlager auf, welche formschlüssig an der Werkzeugspindel arretierbar ist.In the hand-held power tool according to the invention, both pressure cylinders are arranged in the tool spindle, which is necessary anyway, and can also be actuated from an end of the tool spindle on the tool side, the two pressure cylinders being correspondingly connected to one another both in the position that clamps the tool and in the position that does not clamp the tool, and during clamping the actuatable piston of the second pressure cylinder acts on a pressure medium arranged in both pressure cylinders and in the connecting channel, which in turn then causes in the second pressure cylinder that the tension anchor moves from its position not exciting the tool into its position exciting the tool. Preferably A reduction is provided between the second and the first pressure cylinder, ie that a lower force acting on the piston during actuation in the second pressure cylinder leads to a greater force on the tension anchor in the first pressure cylinder. In order to ensure reliable clamping of the tool even when the tool spindle is stressed by changing torques, the manual actuation mechanism has a holding device which can be fastened to the clamping anchor and can be pressed against the abutment, which can be locked in a form-fitting manner on the tool spindle.

Da eine derartige lösbare befestigbare Halteeinrichtung ohnehin notwendig ist, ergibt sich eine optimale kompakte Bauweise, da sowohl die gesamte Vorrichtung zum Andrücken des Spannflansches gegen das Widerlager unter Zwischenklemmen des Werkzeugs als auch der Handbetätigungsmechanismus für diese Vorrichtung bereits in Teilen integriert sind, welche ohnehin in der Regel bei einer derartigen Handwerkzeugmaschine erforderlich sind, so daß nahezu keine Volumenvergrößerung bei der erfindungsgemäßen Lösung die Folge ist.Since such a releasable, attachable holding device is necessary anyway, the result is an optimal, compact design, since both the entire device for pressing the clamping flange against the abutment with intermediate clamping of the tool and the manual actuation mechanism for this device are already integrated in parts, which are already in the As a rule, such a handheld power tool is required, so that there is almost no increase in volume in the solution according to the invention.

Besonders bevorzugt ist ein Ausführungsbeispiel, bei welchem der erste Hohlraum durch einander zugewandte und in axialem Abstand voneinander angeordnete Begrenzungsflächen der Werkzeugspindel sowie des Spannankers und entsprechende Mantelflächen des Spannankers und der Werkzeugspindel definiert ist.An exemplary embodiment is particularly preferred in which the first cavity is defined by mutually facing and axially spaced boundary surfaces of the tool spindle and the tension anchor and corresponding lateral surfaces of the tension anchor and the tool spindle.

Eine konstruktiv besonders einfache Lösung läßt sich dadurch erreichen, daß die Begrenzungsfläche des Spannankers dem Werkzeug zugewandt ist, während die Begrenzungsfläche der Werkzeugspindel dem Werkzeug abgewandt angeordnet ist, so daß eine Volumendilatation im ersten Hohlraum dazu führt, daß die Begrenzungsfläche des Spannankers von dem Werkzeug weg bewegt wird und somit der Spannanker eine direkt das Werkzeug spannende axiale Verschiebung durchführen kann.A structurally particularly simple solution can be achieved in that the boundary surface of the tension anchor faces the tool, while the boundary surface of the tool spindle is arranged facing away from the tool, so that a volume dilation in the first cavity leads to the boundary surface of the tension anchor facing away from the tool is moved and thus the Anchors can perform an axial displacement directly exciting the tool.

Zum Verstellen des Kolbens ist vorteilhafterweise vorgesehen, daß dieser über eine werkzeugseitig offene und sich bis zum Kolben hin erstreckende Bohrung im Spannanker oder in der Werkzeugspindel erfolgt, welche der Handbetätigungsmechanismus durchgreift.To adjust the piston, it is advantageously provided that this takes place via a hole in the clamping anchor or in the tool spindle which is open on the tool side and extends as far as the piston and which the manual actuation mechanism engages through.

Besonders gut läßt sich die erfindungsgemäße Handbetätigungseinrichtung dann in eine Handwerkzeugmaschine integrieren, wenn die Handbetätigungseinrichtung ein verstellbares, den Kolben zum Spannen beaufschlagendes Spannglied umfaßt.The manual control device according to the invention can be integrated particularly well into a hand-held power tool if the manual control device comprises an adjustable clamping element which acts on the piston for clamping.

Das Spannglied kann unmittelbar handbeaufschlagbar und in seiner betätigten Stellung verrastbar sein. Eine leichtere, und vor allem weniger kraftaufwendige Bedienbarkeit des Spannglieds ist dann möglich, wenn dieses eine schräg zu einer Verstellrichtung des Kolbens ausgerichtete Fläche aufweist. Bei dieser Fläche kann es sich beispielsweise um die Mantelfläche eines Exzenters handeln, über welchen beispielsweise mittels einer Kolbenstange der Kolben betätigbar ist. Es kann sich bei der schrägen Fläche aber auch um eine quer zur Verstellrichtung des Kolbens verschiebbare Auflauffläche handeln, welche ebenfalls beispielsweise auf eine Kolbenstange wirkt und dadurch den Kolben verstellt.The tendon can be directly loaded with the hand and locked in its actuated position. Easier and, above all, less forceful operability of the tendon is possible if it has a surface that is oriented obliquely to an adjustment direction of the piston. This surface can be, for example, the lateral surface of an eccentric, via which the piston can be actuated, for example, by means of a piston rod. However, the inclined surface can also be a run-up surface which can be displaced transversely to the direction of adjustment of the piston and which also acts, for example, on a piston rod and thereby displaces the piston.

Die einfachste Realisierungsmöglichkeit der schrägen Fläche ist dann gegeben, wenn das Spannglied ein Gewinde aufweist, dessen Gewindeflächen dann die schrägen Flächen bilden.The simplest possibility of realizing the inclined surface is when the tendon has a thread, the threaded surfaces of which then form the inclined surfaces.

Das Spannglied selbst kann im Rahmen der Handbetätigungseinrichtung an unterschiedlichen Stellen angeordnet sein. So ist bei einer möglichen erfindungsgemäßen Ausführungsform vorgesehen, daß das Spannglied in dem Spannanker oder in der Werkzeugspindel, insbesondere in der sich bis zum Kolben erstreckenden Bohrung angeordnet ist.The tendon itself can be arranged at different points within the scope of the manual control device. Thus, in one possible embodiment according to the invention, it is provided that the tendon is arranged in the tension anchor or in the tool spindle, in particular in the bore extending up to the piston.

Im Hinblick auf die Anordnung des Spannflansches wurden bei den bislang beschriebenen erfindungsgemäßen Lösungen keine weiteren Angaben gemacht. So ist beispielsweise günstig, wenn die Halteeinrichtung den Spannflansch umfaßt.With regard to the arrangement of the clamping flange, no further details were given in the solutions according to the invention described so far. For example, it is favorable if the holding device comprises the clamping flange.

Um diesen Spannflansch an dem Spannanker befestigen zu können, ist vorgesehen, daß die Halteeinrichtung ein an dem Spannanker gegen axiale Verschiebung formschlüssig befestigbares Halteglied aufweist, welches zusammen mit dem Spannflansch durch Formschlußelemente an der Werkzeugspindel drehfest fixierbar ist. Dabei kann das Halteglied in unterschiedlichster Art und Weise ausgebildet sein. So ist es zum Beispiel möglich, wenn das Halteglied in Form eines Bajonettverschlusses mit dem Spannanker verbindbar ist.In order to be able to fasten this tensioning flange to the tensioning anchor, it is provided that the holding device has a holding member which can be positively fastened to the tensioning anchor against axial displacement and which, together with the tensioning flange, can be fixed in a rotationally fixed manner to the tool spindle by form-locking elements. The holding member can be designed in a wide variety of ways. It is possible, for example, if the holding member can be connected to the tension anchor in the form of a bayonet catch.

Eine konstruktive Alternative hierzu sieht vor, daß das Halteglied in den Spannanker einschraubbar ist.A constructive alternative to this provides that the holding member can be screwed into the tension anchor.

Eine besonders bevorzugte Ausführungsform eines Handbetätigungsmechanismus sieht vor, daß das Spannglied und das Halteglied dieselbe Schraube sind, so daß durch Eindrehen dieser Schraube in den Spannanker sowohl eine Befestigung des Spannflansches an diesem als auch gleichzeitig ein Betätigen des Kolbens erfolgen.A particularly preferred embodiment of a manual actuation mechanism provides that the tensioning member and the holding member are the same screw, so that by screwing this screw into the tensioning anchor both the tensioning flange is fastened to the same and the piston is simultaneously actuated.

Hierzu ist es besonders vorteilhaft, wenn die Schraube in einen ersten und einen sich daran anschließenden zweiten Gewindeabschnitt des Spannankers einschraubbar ist und wenn beim Einschrauben in den zweiten Gewindeabschnitt der Kolben betätigbar ist. Eine derartige konstruktive Lösung hat den großen Vorteil, daß zunächst eine Grobsicherung des Spannflansches an dem Spannanker erfolgen kann und bei weiterem Eindrehen der Schraube eine Betätigung des Kolbens erfolgt, welche dann zur endgültigen Spannung des Werkzeugs führt.For this purpose, it is particularly advantageous if the screw can be screwed into a first and an adjoining second threaded section of the tension anchor and if the piston can be actuated when screwing into the second threaded section. Such a constructive solution has the great advantage that first of all a rough securing of the clamping flange on the clamping anchor can take place and, when the screw is screwed in further, the piston is actuated, which then leads to the final clamping of the tool.

Bei diesem Ausführungsbeispiel ist es vorteilhaft, wenn an dem Halteglied der Spannflansch drehbar und in Richtung des Werkzeugs von dieser beaufschlagbar gehalten ist. Dies ist deshalb notwendig, um beim Befestigen des Werkzeugs zu vermeiden, daß das Drehen des Halteglieds durch Reibungskräfte zwischen dem Werkzeug und der Schraube selbst erschwert wird. Liegt jedoch der an dem Halteglied drehbare Spannflansch auf dem Werkzeug an, so kann das Halteglied immer noch gegenüber dem Spannflansch leicht drehbar ausgebildet sein, auch wenn dieses beispielsweise mit einer Schulter den Spannflansch beaufschlagt.In this embodiment, it is advantageous if the clamping flange is rotatably held on the holding member and can be acted upon by it in the direction of the tool. This is necessary in order to avoid, when fastening the tool, that the rotation of the holding member is made difficult by frictional forces between the tool and the screw itself. However, if the clamping flange rotatable on the holding member lies on the tool, the holding member can still be designed so that it can be easily rotated with respect to the clamping flange, even if, for example, a shoulder is applied to the clamping flange.

Ein besonders leichtes Drehen des Halteglieds ist dann erreichbar, wenn zwischen der Schraube und dem Spannflansch ein Axialdrucklager angeordnet ist.A particularly easy turning of the holding member can be achieved if an axial pressure bearing is arranged between the screw and the clamping flange.

Eine formschlüssige Sicherung des Halteglieds kann beispielsweise dadurch erreicht werden, daß eine in radialer Richtung zur Werkzeugspindel verschiebbare Raste vorgesehen wird.A form-fitting securing of the holding member can be achieved, for example, by providing a detent that can be displaced in the radial direction of the tool spindle.

Besonders zweckmäßig ist es jedoch, wenn das Spannglied durch ein in axialer Richtung verschiebbares Sicherungselement sicherbar ist, welches beispielsweise ein in Bohrungen sowohl im Spannglied als auch im Spannflansch eingreifender Bolzen sein kann.However, it is particularly expedient if the tendon can be secured by a locking element which can be displaced in the axial direction, which can be, for example, a bolt which engages in bores in both the tendon and the tensioning flange.

Eine derartige Variante hätte jedoch zur Folge, daß lediglich in bestimmten Relativstellungen zwischen Spannglied und Spannflansch eine Sicherung möglich ist. Aus diesem Grund ist im Rahmen des vorstehenden Ausfühuungsbeispiels zweckmäßigerweise vorgesehen, daß das Sicherungselement drehfest und axial verschiebbar am Spannglied oder am Spannflansch gehalten ist und mit einem zu deren Drehachse koaxialen Zahnkranz des Spannflansches oder des Spanngliedes in Eingriff bringbar ist. Somit ist ein Sichern des Spanngliedes in einem Winkelabstand aufeinanderfolgender Zähne des Zahnkranzes entsprechenden Winkelstellungen möglich.However, such a variant would have the consequence that securing is only possible in certain relative positions between the tendon and the tensioning flange. For this reason, it is expediently provided in the context of the above embodiment that the securing element is held in a rotationally fixed and axially displaceable manner on the tensioning member or on the tensioning flange and can be brought into engagement with a toothed ring of the tensioning flange or tensioning member which is coaxial with its axis of rotation. It is thus possible to secure the tendon at an angular position corresponding to an angular distance between successive teeth of the ring gear.

Schließlich ist es noch vorteilhart, wenn das Sicherungselement in seiner die Schraube sichernden Stellung verrastbar ist.Finally, it is also advantageous if the securing element can be locked in its position securing the screw.

Bei sämtlichen beschriebenen Ausführungsbeispielen wurde nicht im einzelnen darauf eingegangen, welches Druckmedium im ersten Hohlraum, im zweiten Hohlraum und im Verbindungskanal vorgesehen ist.In all of the exemplary embodiments described, no details were given as to which pressure medium is provided in the first cavity, in the second cavity and in the connecting channel.

So ist bei einer bevorzugten Ausführungsform vorgesehen, daß der erste und der zweite Hohlraum sowie der Verbindungskanal mit einer plastischen Masse zur hydraulischen Druckübertragung ausgefüllt sind. Dies ist insbesondere deshalb zweckmäßig, weil mit Handwerkzeugmaschinen bei großen Temperaturunterschieden gearbeitet werden soll und diese dann auch noch zuverlässig funktionieren sollen. Bei Verwendung eines üblichen Hydrauliköls führt dies zu nur schwer oder fast gar nicht beherrschbaren Dichtigkeitsproblemen in den Druckzylindern. Dagegen hat die plastische Massen den Vorteil, daß sich mit dieser derartige Dichtheitsprobleme vermeiden lassen.It is provided in a preferred embodiment that the first and second cavities and the connecting channel are filled with a plastic mass for hydraulic pressure transmission. This is particularly expedient because handheld power tools are to be used when there are large temperature differences and these are then to function reliably. When using a conventional hydraulic oil, this leads to sealing problems in the pressure cylinders that are difficult or almost impossible to control. On the other hand, the plastic mass has the advantage that this type of tightness problem can be avoided.

Besonders bevorzugt ist als plastische Masse ein Polyvinylchlorid mit relativ niedrigem Polymerisationsgrad.A particularly preferred plastic mass is a polyvinyl chloride with a relatively low degree of polymerization.

Alternativ dazu ist es jedoch ebenfalls denkbar, daß der erste Hohlraum, der zweite Hohlraum und der Verbindungskanal mit einer zähflüssigen Masse gefüllt sind, da sich auch mit dieser die oben genannten Dichtigkeitsprobleme vermeiden lassen. Die zähflüssige Masse ist vorzugsweise eine Silikonmasse, insbesondere ein Silikonschmiermittel.Alternatively, however, it is also conceivable for the first cavity, the second cavity and the connecting channel to be filled with a viscous mass, since the above-mentioned tightness problems can also be avoided with this. The viscous mass is preferably a silicone mass, in particular a silicone lubricant.

Darüber hinaus ist es noch von Vorteil, wenn die plastischen oder zähflüssigen Massen kompressibel sind, da diese dann zu einer elastischen und sich an unterschiedliche Ausdehnungen der einzelnen Teile anpassenden Spannung des Werkzeugs führen.In addition, it is also advantageous if the plastic or viscous masses are compressible, since these then become elastic and different The dimensions of the individual parts lead to the tension of the tool being adjusted.

Um jedoch bei der erfindungsgemäßen Lösung auch mit im wesentlichen inkompressiblen Druckübertragungsmedien arbeiten zu können, ist bei einer Variante der erfindungsgemäßen Lösung vorgesehen, daß ein eine axiale Verschiebung des Spannflansches relativ zur Werkzeugspindel erlaubendes elastisches Element vorgesehen ist. Dieses Element kann an den unterschiedlichsten Stellen angeordnet sein. Beispielsweise ist es denkbar, dieses Element zwischen dem Spannflansch und dem diesen beaufschlagenden Halteglied anzuordnen.However, in order to be able to work with essentially incompressible pressure transmission media in the solution according to the invention, it is provided in a variant of the solution according to the invention that an elastic element allowing an axial displacement of the clamping flange is provided relative to the tool spindle. This element can be arranged in a wide variety of locations. For example, it is conceivable to arrange this element between the clamping flange and the holding member acting on it.

Vorzugsweise ist dieses elastische Element so dimensioniert, dass es beim Spannen des Werkzeugs bis zur Unelastizität komprimierbar ist. Damit wird ermöglicht, dass ein noch grösserer Weg beim Spannen erreichbar ist und dass ausserdem dieses elastische Element dann, wenn bei der erfindungsgemässen Einrichtung keine vollkommene Spannung des Werkzeugs durchgeführt wurde, sicherstellt, dass sich das Werkzeug dennoch mit der Werkzeugspindel dreht und somit nicht zu allen möglichen durch eine mangelhafte Spannung hervorgerufenen Unfällen führen kann.This elastic element is preferably dimensioned such that it can be compressed to inelasticity when the tool is clamped. This enables an even greater distance to be reached when clamping and that this elastic element also ensures that if the tool according to the invention has not been completely clamped, it ensures that the tool nevertheless rotates with the tool spindle and thus not to all possible accidents caused by insufficient tension.

Bei einer besonders einfachen Ausführungsform ist das elastische Element ein in einem der Hohlräume angeordnetes volumenelastisches Element, so dass dieses zunächst komprimiert wird und anschliessend das letztendliche Spannen des Werkzeugs durch die Volumenkompression erfolgt.In a particularly simple embodiment, the elastic element is a volume-elastic element arranged in one of the cavities, so that it is first compressed and then the tool is finally clamped by the volume compression.

Weitere Merkmale und Vorteile der Erfindung sind Gegenstand der nachfolgenden Beschreibung sowie der zeichnerischen Darstellung einiger Ausführungsbeispiele. In der Zeichnung zeigen:

Fig. 1
einen Schnitt durch ein erstes Ausführungsbeispiel;
Fig. 2
einen Schnitt ähnlich Fig. 1 durch ein zweites Ausführungsbeispiel.
Further features and advantages of the invention are the subject of the following description and the drawing of some exemplary embodiments. The drawing shows:
Fig. 1
a section through a first embodiment;
Fig. 2
a section similar to FIG. 1 through a second embodiment.

Ein erstes Ausführungsbeispiel einer erfindungsgemässen Winkelschleifmaschine, dargestellt in Fig. 1 umfasst einen zeichnerisch teilsweise dargestellten Antriebsmotor 10, dessen Antriebswelle 12 über ein Antriebsritzel 14 ein Kegelrad 16 einer in einem Getriebegehäuse 18 drehbar gelagerten Werkzeugspindel 20 antreibt. Diese Werkzeugspindel 20 weist an einem Ende einen als Widerlager für ein Werkzeug, insbesondere eine Schleifscheibe 22, dienenden Flansch 24 auf. Die Lagerung der Werkzeugspindel 20 in dem Getriebegehäuse 18 erfolgt auf einer dem Flansch 24 zugewandten Seite mittels eines unteren Lagers 26 sowie auf einer dem Flansch 24 abgewandten Seite mittels eines im Abstand vom unteren Lager 26 angeordneten oberen Lagers 28. Somit ist die Werkzeugspindel 20 um eine Achse 30 drehbar.A first exemplary embodiment of an angle grinding machine according to the invention, shown in FIG. 1, comprises a drive motor 10, partially shown in the drawing, the drive shaft 12 of which drives a bevel gear 16 of a tool spindle 20 rotatably mounted in a gear housing 18 via a drive pinion 14. This tool spindle 20 has at one end a flange 24 serving as an abutment for a tool, in particular a grinding wheel 22. The tool spindle 20 is mounted in the gear housing 18 on a side facing the flange 24 by means of a lower bearing 26 and on a side facing away from the flange 24 by means of an upper bearing 28 arranged at a distance from the lower bearing 26. Thus, the tool spindle 20 is one Axis 30 rotatable.

Die als Hohlspindel ausgebildete Werkzeugspindel 20 umfasst eine koaxiale zentrale Ausnehmung 32, welche sich mit einem aufgeweiteten Abschnitt 36 von einem dem Flansch 24 und somit dem Werkzeug 22 gegenüberliegenden Ende 34 in die Werkzeugspindel 20 hinein erstreckt, über eine Stufenfläche 38 in einen zentralen Abschnitt 40 mit einem bezüglich des aufgeweiteten Abschnitts 36 geringeren Durchmesser übergeht und sich im Anschluss an den zentralen Abschnitt 40 im Bereich des Flansches 24 zu einem mit einer Innenverzahnung 42 versehenen, verzahnten Abschnitt 44 aufweitet, welcher zum Werkzeug 22 hin offen ist.The tool spindle 20, which is designed as a hollow spindle, comprises a coaxial central recess 32 which, with a widened section 36, extends into the tool spindle 20 from an end 34 opposite the flange 24 and thus the tool 22, via a step surface 38 into a central section 40 passes into a smaller diameter with respect to the widened section 36 and, following the central section 40, widens in the region of the flange 24 to form a toothed section 44 which is provided with internal teeth 42 and which is open towards the tool 22.

In dieser Werkzeugspindel 20 ist ein Spannanker 46 in axialer Richtung verschieblich, jedoch drehfest gelagert, welcher ein in dem zentralen Abschnitt 40 der koaxialen Ausnehmung 32 geführtes Mittelstück 48 aufweist, das auf seinem dem Werkzeug 22 abgewandten Ende einen Spannankerkopf 50 trägt, der einen grösseren Durchmesser als das Mittelstück 48 aufweist und in dem aufgeweiteten Abschnitt 36 geführt ist.In this tool spindle 20, a tension anchor 46 is displaceable in the axial direction, but is mounted in a rotationally fixed manner, which has a center piece 48 guided in the central section 40 of the coaxial recess 32, which carries on its end facing away from the tool 22 a tension anchor head 50 which has a larger diameter than the middle piece 48 and is guided in the expanded section 36.

Dieser Spannankerkopf 50 weist auf seiner der Stufenfläche 38 zugewandten Seite eine sich bis zu einer Mantelfläche 52 des Mittelstücks 48 reichende Kreisringfläche 54 auf, welche zusammen mit der Mantelfläche 52 des Mittelstücks 48, der Stufenfläche 38 und dem aufgeweiteten Abschnitt 36 der koaxialen Ausnehmung 32 einen ersten Hohlraum 56 eines ersten Druckzylinders, gebildet durch die Werkzeugspindel 20 und den in dieser verschieblichen Spannanker 46, begrenzt.On its side facing the step surface 38, this tension anchor head 50 has an annular surface 54 which extends up to a lateral surface 52 of the central piece 48, which together with the lateral surface 52 of the central piece 48, the step surface 38 and the widened section 36 of the coaxial recess 32 has a first Cavity 56 of a first pressure cylinder, formed by the tool spindle 20 and the clamping anchor 46 displaceable therein, is limited.

Um ein einwandfreies Arbeiten dieses ersten Druckzylinders zu ermöglichen, ist das Mittelstück 48 mit einer gegenüber dem zentralen Abschnitt 40 der koaxialen Ausnehmung wirksamen Ringdichtung 58 versehen und der Spannankerkopf 50 mit einer gegenüber dem aufgeweiteten Abschnitt 36 wirksamen Ringdichtung 60.To enable this first pressure cylinder to work properly, the middle piece 48 is provided with an annular seal 58 which is effective with respect to the central section 40 of the coaxial recess, and the tension anchor head 50 is provided with an annular seal 60 which is effective with respect to the expanded section 36.

Der Spannanker 46 ist ausserdem seinerseits mit einer diesen von Seiten des Spannankerkopfes 50 her durchdringenden Mittelbohrung 62 versehen, in welche im Bereich des Spannankerkopfs 50 eine Verschlussschraube 64 eingedreht ist. Von dieser Mittelbohrung 62 ausgehend erstrecken sich in radialer Richtung verlaufende und in einem dem Spannankerkopf 50 zugewandten Bereich des Mittelstücks 48 angeordnete Verbindungskanäle 66 zu dem ersten Hohlraum 56.The tension anchor 46 is in turn also provided with a central bore 62 penetrating it from the side of the tension anchor head 50, into which a screw plug 64 is screwed in the area of the tension anchor head 50. Starting from this central bore 62, connecting channels 66 extending in the radial direction and arranged in a region of the central piece 48 facing the tension anchor head 50 extend to the first cavity 56.

Werkzeugseitig dieser Verbindungskanäle 66 ist in der Mittelbohrung 62 ein dichtend in dieser geführter Kolben 68 angeordnet, welcher einen zweiten Hohlraum 70 festlegt, der einerseits durch den Kolben 68, andererseits durch die Verschlussschraube 64 sowie durch einen zwischen beiden liegenden Bohrungsabschnitt 72 der Mittelbohrung 62 begrenzt ist.On the tool side of these connecting channels 66, a piston 68 is sealingly arranged in the central bore 62 and defines a second cavity 70 which is delimited on the one hand by the piston 68, on the other hand by the screw plug 64 and by a bore section 72 of the central bore 62 lying between the two .

Der Kolben 68 selbst ist von seiner dem Werkzeug 22 zugewandten Seite her durch eine Kolbenstange 74 beaufschlagt, welche sich vom Kolben 68 weg durch die Mittelbohrung 62 in Richtung des Werkzeugs 22 erstreckt.The piston 68 itself is acted upon from its side facing the tool 22 by a piston rod 74 which extends away from the piston 68 through the central bore 62 in the direction of the tool 22.

Zum Werkzeug 22 hin ist der Spannanker 46 mit einer Gewindebohrung 76 versehen, in welche die vom Spannankerkopf 50 herkommende Mittelbohrung 62 übergeht, wobei die Gewindebohrung 76 einen grösseren Durchmesser aufweist als die Mittelbohrung 62.Toward the tool 22, the tension anchor 46 is provided with a threaded bore 76 into which the central bore 62 originating from the tension anchor head 50 merges, the threaded bore 76 has a larger diameter than the central bore 62.

Die Kolbenstange 74 ist so dimensioniert, dass sie aus der Mittelbohrung 62 heraus in einen zweiten Gewindeabschnitt 78 der Gewindebohrung 76 hinein übersteht, welcher sich an die Mittelbohrung 62 anschliesst. Auf diesen zweiten Gewindeabschnitt 78 folgt in axialer Richtung zum Werkzeug 22 hin ein erster Gewindeabschnitt 80 der Gewindebohrung 76.The piston rod 74 is dimensioned such that it projects out of the central bore 62 into a second threaded section 78 of the threaded bore 76, which adjoins the central bore 62. This second threaded section 78 is followed in the axial direction towards the tool 22 by a first threaded section 80 of the threaded bore 76.

Das Halten des Werkzeugs, das heisst in diesem Falle der Schleifscheibe 22, erfolgt mittels eines Spannflansches 82, welcher Teil einer als Ganzes mit 84 bezeichneten Halteeinrichtung ist. Diese Halteeinrichtung 84 umfasst eine Halteschraube 86, welche mit einem Gewindebolzen 88 von seiten des Werkzeugs 22 her in die Gewindebohrung 76 einschraubbar ist. An diesen Gewindebolzen 88 der Halteeinrichtung 84 schliesst sich ein zylindrisches Stück 90 an, welches auf seinem dem Gewindebolzen 88 gegenüberliegenden Ende einen kreisscheibenförmig ausgebildeten Schraubenkopf 92 trägt, welcher sich im wesentlichen parallel zum Flansch 24 erstreckt und einen mit diesem ungefähr vergleichbaren Durchmesser aufweist. Dieser Schraubenkopf 92 beaufschlagt über ein an seiner dem Flansch 24 zugewandten Seite angeordnetes Axialdrucklager 94 den Spannflansch 82, welcher zum Halten der Schleifscheibe 22 diese zwischen sich und dem als Widerlager ausgebildeten Flansch 24 einklemmt.The tool, that is to say the grinding wheel 22 in this case, is held by means of a clamping flange 82, which is part of a holding device designated as a whole by 84. This holding device 84 comprises a holding screw 86 which can be screwed into the threaded bore 76 from the side of the tool 22 using a threaded bolt 88. Connected to this threaded bolt 88 of the holding device 84 is a cylindrical piece 90, which carries on its end opposite the threaded bolt 88 a circular disk-shaped screw head 92 which extends essentially parallel to the flange 24 and has a diameter approximately comparable to this. This screw head 92 acts on the clamping flange 82 via an axial pressure bearing 94 arranged on its side facing the flange 24, which clamps the grinding wheel 22 between it and the flange 24 designed as an abutment in order to hold the grinding wheel 22.

An den Spannflansch 82 ist eine das zylindrische Stück 90 umgebende Hülse 96 angeformt, welche drehbar an dem zylindrischen Stück 90 gelagert ist. Diese Hülse 96 trägt eine Aussenverzahnung 98, welche mit der Innenverzahnung 42 des verzahnten Abschnitts 44 der koaxialen Ausnehmung 32 in Eingriff bringbar ist. Somit ist die Hülse 96 in axialer Richtung in den verzahnten Abschnitt 44 hinein verschiebbar, jedoch in diesem gegenüber der Werkzeugspindel 20 drehfest gehalten.A sleeve 96, which surrounds the cylindrical piece 90 and is rotatably mounted on the cylindrical piece 90, is formed on the clamping flange 82. This sleeve 96 carries one External teeth 98, which can be brought into engagement with the internal teeth 42 of the toothed section 44 of the coaxial recess 32. The sleeve 96 can thus be displaced in the axial direction into the toothed section 44, but is held non-rotatably in the latter relative to the tool spindle 20.

Bei dem in Fig. 1 dargestellten Ausführungsbeispiel haben sowohl der Schraubenkopf 92 als auch der Spannflansch 82 denselben Durchmesser und beide sind an ihren bezüglich der Achse 30 radial aussen liegenden Flächen mit einer Verzahnung 100 bzw. 102 versehen, wobei beide Verzahnungen 100 bzw. 102 miteinander identisch ausgebildet sind. Die beiden Verzahnungen 100, 102 haben vorzugsweise in einem Winkelabstand von ungefähr 5° angeordnete Zähne. Mit diesen ist ein Innenzahnkranz 104 einer Abdeckkappe 106 in Eingriff bringbar, welche den Schraubenkopf 92 auf seiner dem Werkzeug 22 abgewandten Stirnseite 112 sowie den Schraubenkopf 92 als auch den Spannflansch 82 im Bereich ihrer radial aussen liegenden Verzahnungen 100 bzw. 102 übergreift.In the exemplary embodiment shown in FIG. 1, both the screw head 92 and the clamping flange 82 have the same diameter and both are provided with teeth 100 and 102 on their surfaces lying radially outside with respect to the axis 30, both teeth 100 and 102 with one another are identical. The two toothings 100, 102 preferably have teeth arranged at an angular distance of approximately 5 °. With these, an internal ring gear 104 of a cover cap 106 can be brought into engagement, which overlaps the screw head 92 on its end face 112 facing away from the tool 22 and the screw head 92 as well as the clamping flange 82 in the region of their radially outer toothings 100 and 102.

Diese Abdeckkappe 106 ist mittels eines Stifts 108 an der Halteschraube 86 dadurch gelagert, dass dieser Stift 108 in eine sich von der Stirnseite 112 in die Halteschraube 86 hinein erstreckende Innenbohrung 110 eingreift. Dadurch ist die gesamte Abdeckkappe durch den in der Innenbohrung 110 geführten Stift 108 in Richtung der Achse 30 verschiebbar, so dass der Innenzahnkranz 104 entweder nur mit der Verzahnung 100 des Schraubenkopfs 92 in Eingriff ist oder sowohl mit der Verzahnung 100 des Schraubenkopfs 92 als als auch mit der Verzahnung 102 des Spannflansches 82.This cover cap 106 is mounted on the retaining screw 86 by means of a pin 108 in that this pin 108 engages in an inner bore 110 which extends from the end face 112 into the retaining screw 86. As a result, the entire cover cap can be displaced in the direction of the axis 30 by the pin 108 guided in the inner bore 110, so that the inner toothed ring 104 either engages only with the toothing 100 of the screw head 92 or both with the toothing 100 of the screw head 92 as as well as with the toothing 102 of the clamping flange 82.

Um die Abdeckkappe 106 in ihrer in beide Verzahnungen 100 und 102 eingreifenden Stellung arretieren zu können, ist der Stift 108 mit einer ersten Ringnut 114 versehen, in welche ein in einer umlaufenden Nut 116 der Innenbohrung 110 gelagerter Haltering 118 dann eingreift, wenn beide Verzahnungen 100 und 102 mit dem Innenzahnkranz 104 in Eingriff sind. Außerdem ist der Stift 108 zusätzlich mit einer zweiten Ringnut 120 versehen, in welche der Haltering 118 dann eingreift, wenn der Innenzahnkranz 104 lediglich noch mit der Verzahnung 100 in Eingriff ist.In order to be able to lock the cover cap 106 in its position engaging in both toothings 100 and 102, the pin 108 is provided with a first annular groove 114 into which a retaining ring 118 mounted in a circumferential groove 116 of the inner bore 110 engages when both toothings 100 and 102 are engaged with the internal ring gear 104. In addition, the pin 108 is additionally provided with a second annular groove 120, into which the retaining ring 118 engages when the internal ring gear 104 is only engaged with the toothing 100.

Das in Fig. 1 dargestellte erfindungsgemäße Ausführungsbeispiel funktioniert nun folgendermaßen:The exemplary embodiment according to the invention shown in FIG. 1 now functions as follows:

Zum Montieren der Schleifscheibe 22 wird die gesamte Halteeinrichtung 84 durch Herausschrauben des Gewindebolzens 88 aus der Gewindebohrung 76 abgenommen. Nunmehr kann eine neue Schleifscheibe 22 an dem Flansch 24 angelegt werden.To mount the grinding wheel 22, the entire holding device 84 is removed by unscrewing the threaded bolt 88 from the threaded bore 76. A new grinding wheel 22 can now be placed on the flange 24.

Danach wird die Halteeinrichtung 84 eingesetzt, wobei die an den Spannflansch 82 angeformte Hülse 96 so zu verdrehen ist, daß deren Außenverzahnung 98 mit der Innenverzahnung 42 des verzahnten Abschnitts 44 der koaxialen Ausnehmung 32 in Eingriff kommt. Diese Hülse 96 sorgt somit dafür, daß der Spannflansch 82 selbst drehfest mit der Werkzeugspindel 20 verbunden ist. Anschließend wird die Halteschraube 86 mit ihrem Gewindebolzen 88 bei lediglich mit der Verzahnung 100 in Eingriff stehender Abdeckkappe in die Gewindebohrung 76 des Spannankers 46 eingeschraubt, wobei sich der Gewindebolzen 88 zuerst in den ersten Gewindeabschnitt 80 eindreht und dann den sich daran anschließenden zweiten Gewindeabschnitt 78 erreicht. Sobald der Gewindebolzen 88 diesen zweiten Gewindeabschnitt 78 erreicht, beaufschlagt dieser mit seiner Frontfläche 122 das dieser zugewandte Ende der Kolbenstange 74 und somit über die Kolbenstange 74 auch den Kolben 68. Dies ist bei der erfindungsgemäßen Lösung dann der Fall, wenn die Halteschraube 86 mit dem Gewindebolzen 88 bereits so weit eingeschraubt ist, daß der Spannflansch 82 auf der Schleifscheibe 22 anliegt und diese auch gegen den Flansch 24 anlegt, wobei der Spannflansch 82 durch den Schraubenkopf 92 über das Axialdrucklager 94 beaufschlagt ist. Liegt der Spannflansch 82 an der Schleifscheibe 22 bereits dann an, wenn die Frontfläche 122 mit der Kolbenstange 74 noch keinen Kontakt hat, so wird der Spannanker 46 so lange in Richtung des Werkzeugs 22 gezogen, bis die Bewegung des Spannankers 46 selbst und die Verdrängung von Druckübertragungsmedium aus dem ersten Hohlraum 56 in den zweiten Hohlraum 70 über den Kolben 68, die Kolbenstange 74 mit der Frontfläche 122 in Berührung gebracht haben. Der umgekehrte Vorgang läuft dann ab, wenn die Frontläche 122 an der Kolbenstange 74 anliegt, bevor der Spannflansch 82 die Schleifscheibe 22 am Flansch 24 anlegt.Thereafter, the holding device 84 is inserted, the sleeve 96 integrally formed on the clamping flange 82 being rotated such that its external toothing 98 comes into engagement with the internal toothing 42 of the toothed section 44 of the coaxial recess 32. This sleeve 96 thus ensures that the clamping flange 82 is non-rotatably connected to the tool spindle 20. The retaining screw 86 is then screwed with its threaded bolt 88 into the threaded bore 76 of the tensioning anchor 46 with the cover cap only engaged with the toothing 100, whereby the threaded bolt 88 first turns into the first threaded section 80 and then reaches the adjoining second threaded section 78. As soon as the threaded bolt 88 reaches this second threaded section 78, its front surface 122 acts on the end of the piston rod 74 facing it and thus also on the piston 68 via the piston rod 74. This is the case with the solution according to the invention when the retaining screw 86 with the Threaded bolt 88 is already screwed in so far that the clamping flange 82 lies on the grinding wheel 22 and also abuts it against the flange 24, the clamping flange 82 being acted upon by the screw head 92 via the thrust bearing 94. If the clamping flange 82 is already on the grinding wheel 22 when the front surface 122 has no contact with the piston rod 74, the clamping anchor 46 is pulled in the direction of the tool 22 until the movement of the clamping anchor 46 itself and the displacement of Pressure transmission medium from the first cavity 56 into the second cavity 70 via the piston 68 which have brought the piston rod 74 into contact with the front surface 122. The reverse process takes place when the front surface 122 abuts the piston rod 74 before the clamping flange 82 contacts the grinding wheel 22 on the flange 24.

Wird nun die Halteschraube 86 ab diesem Punkt weitergedreht, so zieht einerseits der Gewindebolzen 88 durch den Eingriff in die Gewindebohrung 76 den gesamten Spannanker 46 in Richtung des Flansches 24, so daß der erste Hohlraum 56 des ersten Druckzylinders sich verkleinert, da die Kreisringfläche 54 und die Stufenfläche 38 aufeinanderzu bewegt werden. Gleichzeitig drückt jedoch die Frontfläche 122 über die Kolbenstange 74 den Kolben 68 in Richtung des Spannankerkopfes 50, so daß auch der zweite Hohlraum 70 ebenfalls verkleinert wird.If the retaining screw 86 is rotated further from this point, the threaded bolt 88 pulls the entire tension anchor 46 in the direction of the flange 24 by engaging in the threaded bore 76, so that the first cavity 56 of the first pressure cylinder is reduced, since the annular surface 54 and the step surface 38 towards each other be moved. At the same time, however, the front surface 122 presses the piston 68 in the direction of the tension anchor head 50 via the piston rod 74, so that the second cavity 70 is also reduced.

Bei einem vorteilhaften Ausführungsbeispiel sind der erste Hohlraum 56, der zweite Hohlraum 70 und auch die Verbindungskanäle 66 mit einer plastischen Masse, vorzugsweise einem Polyvinylchlorid mit relativ niedrigem Polimerisationsgrad, gefüllt. Diese plastische Masse wird durch die Verkleinerung des ersten Holraums 56 und gleichzeitige Verkleinerung des zweiten Hohlraums 70 beim Weiterhineindrehen der Halteschraube 86 unter Druck gesetzt, so daß diese plastische Masse bestrebt ist, den Spannanker 46 als Ganzes von dem Flansch 44 weg zu bewegen,und dadurch eine zusätzliche axiale Zugkraft auf die Halteschraube 86 ausübt, so daß diese über das Axialdrucklager 94 und den Spannflansch 82 die Schleifscheibe 22 fest gegen den Flansch 24 drückt und somit die Schleifscheibe mit der notwendigen Kraft zwischen Spannflansch 82 und Flansch 24 einspannt.In an advantageous embodiment, the first cavity 56, the second cavity 70 and also the connecting channels 66 are filled with a plastic mass, preferably a polyvinyl chloride with a relatively low degree of polymerization. This plastic mass is pressurized by the reduction in the first cavity 56 and the simultaneous reduction in the second cavity 70 when the retaining screw 86 is screwed in, so that this plastic mass tends to move the tension anchor 46 as a whole away from the flange 44, and thereby exerts an additional axial tensile force on the retaining screw 86 so that it presses the grinding wheel 22 firmly against the flange 24 via the thrust bearing 94 and the clamping flange 82 and thus clamps the grinding wheel with the necessary force between the clamping flange 82 and the flange 24.

Die vorteilhafte Wirkung der beiden miteinander arbeitenden Druckzylinder ist darin zu sehen, daß dann, wenn der Gewindebolzen 88 mit seiner Frontfläche 122 auf die Kolbenstange 74 zu wirken beginnt, eine geringe Drehung der Halteschraube 86 sowohl den ersten Hohlraum 56 als auch den zweiten Hohlraum 70 verkleinert und damit die plastische Masse mit hohen Kräften vorspannt, wobei ausserdem das Übersetzungsverhältnis zwischen der Wirkung des Kolbens 68 mit einer kleinen Kolbenfläche und den als große Kolbenflächen wirkenden Kreisringflächen 54 und 38 zum Tragen kommt. Ausserdem hat die plastische Masse eine gewisse Elastizität und dient somit als in gewissen Grenzen volumenkompressibles elastisches Element, welches es erlaubt, im angedrehten Zustand der Halteschraube 86 die Schleifscheibe 22 gespannt zu halten.The advantageous effect of the two pressure cylinders working together can be seen in the fact that when the threaded bolt 88 begins to act on the piston rod 74 with its front surface 122, a slight rotation of the retaining screw 86 reduces both the first cavity 56 and the second cavity 70 and thus prestresses the plastic mass with high forces, the transmission ratio between the action of the piston 68 with a small piston area and the circular ring surfaces 54 and 38 acting as large piston areas also being effective. In addition, the plastic mass has a certain elasticity and thus serves as a volume-compressible elastic element, which allows the grinding wheel 22 to be held tensioned when the retaining screw 86 is turned on.

Ausserdem kommt hinzu, daß bei laufender Maschine sich die Werkzeugspindel 20 und somit auch die plastische Masse erwärmt, die sich dann ausdehnt und somit die Kraft auf den Spannanker 46 vergrössert. Um den angedrehten Zustand der Halteschraube 86 während des Arbeitens mit dem erfindungsgemässen Winkelschleifer fixieren zu können, wird die Abdeckkappe 106 nach dem Andrehen in axialer Richtung so weit verschoben, daß deren Innenzahnkranz 104 auch noch mit der Verzahnung 102 in Eingriff kommt, so dass sich der Schraubenkopf 92 nicht mehr gegenüber dem Spannflansch 82 verdrehen kann, wobei letzterer seinerseits durch die mit der Innenverzahnung 42 der Werkzeugspindel 20 in Eingriff stehende Aussenverzahnung 98 an dieser drehfest gehalten ist, so dass insgesamt kein Verdrehen des Schraubenkopfes 92 gegenüber der Werkzeugspindel 20 mehr möglich ist.In addition, when the machine is running, the tool spindle 20 and thus also the plastic mass heats up, which then expands and thus increases the force on the clamping anchor 46. To the screwed-on state of the retaining screw 86 while working with the inventive To be able to fix the angle grinder, the cover cap 106 is moved so far in the axial direction after tightening that the internal ring gear 104 also comes into engagement with the toothing 102, so that the screw head 92 can no longer rotate relative to the clamping flange 82, the latter for its part is held on the external toothing 98, which is in engagement with the internal toothing 42 of the tool spindle 20, so that no turning of the screw head 92 relative to the tool spindle 20 is possible.

Bei einem zweiten Ausführungsbeispiel der erfindungsgemässen Lösung dargestellt in Fig. 2, sind, insoweit als dieselben Teile wie beim ersten Ausführungsbeispiel verwendet sind, diese mit denselben Bezugszeichen versehen, so dass hinsichtlich deren Beschreibung auf das erste Ausführungsbeispiel verwiesen werden kann.In a second exemplary embodiment of the solution according to the invention shown in FIG. 2, insofar as the same parts are used as in the first exemplary embodiment, they are provided with the same reference numerals, so that reference can be made to the first exemplary embodiment with regard to their description.

Im Gegensatz zum ersten Ausführungsbeispiel des erfindungsgemässen Winkelschleifers ist im Abstand von der Stufenfläche 38 ein sich zwischen dem aufgeweiteten Abschnitt 36 der koaxialen Ausnehmung 32 und der Mantelfläche 52 des Mittelstücks 48 erstreckender Kolbenring 130 vorgesehen, welcher dichtend zwischen diesen beiden Flächen abschliesst und sich mittels Tellerfedern 132 auf der Stufenfläche 38 abstützt. Der erste Hohlraum 56′ des zweiten Ausführungsbeispiels wird daher nicht durch die Stufenfläche 38, sondern durch eine der Kreisringfläche 54 zugewandte Kolbenringfläche 134 begrenzt.In contrast to the first exemplary embodiment of the angle grinder according to the invention, a piston ring 130 is provided at a distance from the step surface 38 and extends between the widened section 36 of the coaxial recess 32 and the outer surface 52 of the center piece 48, which seals between these two surfaces and is sealed by means of disc springs 132 is supported on the step surface 38. The first cavity 56 'of the second embodiment is therefore not limited by the step surface 38, but by a piston ring surface 134 facing the annular surface 54.

Die Tellerfedern 132 haben die Aufgabe, beim Andrehen der Halteschraube 86 als zusätzliches elastisches Element zu wirken, so daß dann, wenn der Gewindebolzen 88 mit seiner Frontfläche 122 die Kolbenstage 74 beaufschlagt, noch ein Weiterdrehen um einen erheblichen Winkel möglich ist, da das Andrehen der Halteschraube 86 nicht durch die Elastizität der plastischen Masse begrenzt ist, sondern zunächst bei weiterem Andrehen die Tellerfedern 132 zusammengedrückt werden, so lange bis der Kolbenring 130 über die zusammengedrückten Tellerfedern 132 durch die Stufenfläche 38 abgestützt ist. Erst danach erfolgt noch ein geringes Komprimieren der in dem ersten Hohlraum 56′, dem zweiten Hohlraum 70 und den Verbindungskanälen 66 angeordneten plastischen Masse, um ein endgültiges Spannen der Schleifscheibe 22 zu erreichen.The plate springs 132 have the task of acting as an additional elastic element when tightening the retaining screw 86, so that when the threaded bolt 88 acts on the piston surface 74 with its front surface 122, further rotation is possible by a considerable angle, since the tightening of the Retaining screw 86 is not limited by the elasticity of the plastic mass, but first the disk springs 132 are compressed when the screw is turned further until the piston ring 130 is supported by the stepped surface 38 via the compressed disk springs 132. Only then is there a slight compression of the plastic mass arranged in the first cavity 56 ', the second cavity 70 and the connecting channels 66 in order to achieve a final tensioning of the grinding wheel 22.

Ferner ist das Axialdrucklager 94 mit einem dieses umgebenden Filzring 95 gegen Verschmutzung abgedichtet.Furthermore, the thrust bearing 94 is sealed against contamination by a felt ring 95 surrounding it.

Claims (26)

  1. Hand-operated machine tool, with a device for clamping a disc-like tool (22) on a tool spindle (20) drivable in rotation by a motor, especially for clamping a grinding wheel on an angle grinder, with a clamping tie (46) which is arranged in the tool spindle (20) provided with an axial recess and which is axially displaceable relative to said tool spindle (20) and is connected fixedly in terms of rotation to the latter, with a clamping flange (82) which can be fastened releasably to the free end of the clamping tie (46), with an abutment arranged at the tool-facing end of the tool spindle (20), and with a device, actuable by means of a hand-actuating mechanism, for pressing the clamping flange (82) releasably against the abutment, the tool (22) thereby being gripped between them, characterised in that the device has a first pressure cylinder comprising a first cavity (56) between the clamping tie (46) and the tool spindle (20), a second pressure cylinder comprising a second cavity (70) arranged in the clamping tie (46) or in the tool spindle (20), and a connecting channel (66) between the two cavities (56, 70), in that the second pressure cylinder comprises a piston (68) which limits the second cavity (70) and which, for the releasable clamping of the tool (22), can be adjusted by the hand-actuating mechanism from a tool-facing end of the tool spindle (20) and can be fixed in its position clamping the tool (22), in that the hand-actuating mechanism has a holding device (84) which can be fastened releasably to the clamping tie (46) and which can be operated manually to press the clamping flange (82) against the abutment, and in that the holding device (84) can be secured positively to the tool spindle (20) fixedly in terms of rotation.
  2. Machine according to Claim 1, characterised in that the first cavity (56) is defined by mutually confronting axially spaced limiting faces (38, 54) of the tool spindle (20) and of the clamping tie (46).
  3. Machine according to Claim 2, characterised in that the limiting face (54) of the clamping tie (46) confronts the tool (22), whilst the limiting face (38) of the tool spindle (20) is arranged turned away from the tool (22).
  4. Machine according to one of the preceding claims, characterised in that an adjustment of the piston (68) takes place via a bore (62) in the clamping tie (46) or in the tool spindle (20), said bore (62) being open towards the tool, extending as far as the piston and passing through the hand-actuating mechanism.
  5. Machine according to Claim 1, characterised in that the hand-actuating mechanism is arranged in a tool-facing region of the clamping tie (46) or of the tool spindle (20).
  6. Machine according to one of the preceding claims, characterised in that the hand-actuating mechanism comprises an adjustable clamping member (86, 144) loading the piston (68) for the purpose of clamping.
  7. Machine according to Claim 5, characterised in that the clamping member (86, 144) has a face oriented obliquely to an adjusting direction of the piston (68).
  8. Machine according to Claim 5, characterised in that the clamping member (86, 144) has a thread.
  9. Machine according to one of Claims 6 to 8, characterised in that the clamping member (86, 144) is arranged on the holding device (84).
  10. Machine according to one of the preceding claims, characterised in that the holding device (84) surrounds the clamping flange (82).
  11. Machine according to one of the preceding claims, characterised in that the holding device (84) comprises a holding member (86) which can be fastened to the clamping tie (46) and which, together with the clamping flange (82), can be secured to the tool spindle (20) fixedly in terms of rotation by means of positive-connection elements (42, 98).
  12. Machine according to Claim 11, characterised in that the holding member (86) can be screwed into the clamping tie (46).
  13. Machine according to Claim 12, characterised in that the clamping member and the holding member are the same screw (86).
  14. Machine according to Claim 13, characterised in that the screw (86) can be screwed into a first (80) and an adjoining second (78) threaded portion of the clamping tie (46) and in that the piston (68) can be actuated during the screwing into the second threaded portion (78).
  15. Machine according to one of Claims 11 to 14, characterised in that the clamping flange (82) is held on the holding member (86) so as to be rotatable and so that it can be loaded in the direction of the tool (22) by the latter.
  16. Machine according to Claim 15, characterised in that an axial thrust bearing (94) is arranged between the holding member (86) and the clamping flange (82).
  17. Machine according to one of Claims 11 to 16, characterised in that the holding member (86) can be secured by a securing element (106) displaceable in the axial direction.
  18. Machine according to Claim 17, characterised in that the securing element (106) is held on the holding member (86) or on the clamping flange (82) fixedly in terms of rotation and axially displaceably and can be brought into engagement with a toothed rim, coaxial to their axis of rotation (30), of the clamping flange (102) or of the clamping member (100).
  19. Machine according to one of Claims 17 or 18, characterised in that the securing element (106) can be locked in its position securing the clamping member (86).
  20. Machine according to one of the preceding claims, characterised in that the first and the second cavity (56, 70) and the connecting channel (66) are filled with a plastic mass for hydraulic pressure transmission.
  21. Machine according to Claim 20, characterised in that the plastic mass comprises polyvinyl chloride having a relatively low degree of polymerisation.
  22. Machine according to one of Claims 1 to 19, characterised in that the first cavity (56), the second cavity (70) and the connecting channel (66) are filled with a viscous mass.
  23. Machine according to Claim 22, characterised in that the viscous mass is a silicone mass, especially a silicone lubricant.
  24. Machine according to one of the preceding claims, characterised in that an elastic element (130, 132) allowing an axial displacement of the clamping flange (82) relative to the tool spindle (20) is provided.
  25. Machine according to Claim 24, characterised in that the elastic element (130, 132) can be compressed to inelasticity during the clamping of the tool (22).
  26. Machine according to Claim 24 or 25, characterised in that the elastic element is an element (130, 132) of elastic volume arranged in one of the cavities (56).
EP89100067A 1988-01-09 1989-01-04 Device for clamping a disc-like tool Expired - Lifetime EP0324357B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3800437 1988-01-09
DE3800437 1988-01-09

Publications (3)

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EP0324357A2 EP0324357A2 (en) 1989-07-19
EP0324357A3 EP0324357A3 (en) 1990-06-13
EP0324357B1 true EP0324357B1 (en) 1993-05-19

Family

ID=6345008

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89100067A Expired - Lifetime EP0324357B1 (en) 1988-01-09 1989-01-04 Device for clamping a disc-like tool

Country Status (4)

Country Link
US (1) US5199223A (en)
EP (1) EP0324357B1 (en)
JP (1) JPH01216770A (en)
DE (1) DE58904372D1 (en)

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DE10258372B4 (en) 2001-12-12 2004-12-30 S-B Power Tool Company, Broadview tensioning assembly
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US7179156B2 (en) * 2005-03-23 2007-02-20 Gison Machinery Co., Ltd. Grinder with easily installable/detachable grinding disc and a linkage effect
US20070163412A1 (en) * 2006-01-15 2007-07-19 Anthony Baratta Methods and apparatus for movable machining tools, including for wall saws
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US8328475B2 (en) * 2007-11-28 2012-12-11 Milwaukee Electric Tool Corporation Cutting tool assembly including a release mechanism
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Also Published As

Publication number Publication date
US5199223A (en) 1993-04-06
JPH01216770A (en) 1989-08-30
EP0324357A3 (en) 1990-06-13
DE58904372D1 (en) 1993-06-24
EP0324357A2 (en) 1989-07-19

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