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
  • B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
  • B24B23/04—Portable grinding machines, e.g. hand-guided; Accessories therefor with oscillating grinding tools; Accessories therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
  • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
  • B25F5/008—Cooling means

Definitions

• the invention relates to a motor-driven hand unit according to the preamble of claim 1.
• the Invention motor-driven hand-held unit with the features of claim 1 has the following advantages.
• the circumferential axial sealing element seals the bearing from the dust chamber, so that neither dust can get into the bearing nor any bearing grease can escape from the bearing and get into the dust chamber. This considerably increases the life of the bearing.
• the bearing in particular deep groove ball bearing, has sealing disks that are integrated on both sides, touching or not touching, which are seated in particular on the outer ring and in relation to the axial end face of the inner ring further inside and at a distance from it.
• a disk rotating with it can be arranged on the shaft, which lies against the facing end face of the inner ring and the integrated sealing disk of the bearing with at least a small axial distance radially covered.
• the disk is formed from a thin sheet and if the disk and, via this, the inner ring of the bearing are secured axially on the shaft by means of a retaining ring. This results in a simple and cost-effective sealing of the bearing on the opposite axial side, where less dust is produced when the hand-held unit is designed as a grinding device.
• the shaft on the axial side of the fan wheel facing away from the axial sealing element has a z. B. carries eccentric sleeve on the - z. B. by means of an associated sleeve-shaped inner ring - a grinding plate is rotatably supported by a bearing.
• the bearing of the grinding plate can be formed from an open needle sleeve and can be axially sealed on the axial side which faces the fan wheel by means of at least one sealing element which is designed as a radial shaft sealing ring.
• the at least one sealing element of the bearing can be designed as a sealing ring corresponding in cross-section to a lying U and bearing two striving sealing lips. In this way, a dust seal of the bearing assigned to the grinding plate is achieved in a simple manner on the axial side facing the dust chamber. Drawing -.
• FIG. 2 shows an enlarged detail from FIG. 1.
• a motor-driven hand tool 1 in particular grinding device, for. B. Orbital sander, shown, which has a housing 2, in whose upper housing part 12 an electric motor 3 is contained, which drives a grinding plate 11 designed as an oscillating member via a coaxial shaft 10.
• the shaft 10 is supported in the housing part 12 by means of a bearing 13.
• the housing part 12 surrounds a fan wheel 14 which is located within a dust space 15 delimited by the housing part 12 and is arranged on the shaft 10 in a rotationally fixed manner by means of a sleeve 18, so that it rotates with the shaft 10.
• the bearing 13 is located outside the dust chamber 15 and is in an approximately cup-shaped receptacle 16 of the housing part 12 recorded in such a way that a bottom part 17 of the receptacle 16 covers the bearing 13 on the side facing the fan wheel 14, the bottom part 17 having a passage 19 through which the shaft 10 with the sleeve 18 extends.
• the bearing 13 is designed, for example, as a deep groove ball bearing, the outer ring 20 of which is held non-rotatably in the approximately cup-shaped receptacle 16 and can be axially supported on the bottom part 17 thereof.
• the inner ring 21 sits on the shaft 10 in a rotationally fixed manner.
• the bottom part 17 is dimensioned such that it extends radially approximately to the inner ring 21.
• the bearing 13, in particular in the form of a ball groove bearing, is sealed on the axial side which faces the fan wheel 14 with respect to the fan wheel 14 by means of an axial sealing element 30 which runs together with the shaft 10 and the sleeve 18.
• the sealing element 30 is formed from an annular, flexible and in particular rubber-elastic shaft seal and has a sealing body 31 and a flexible sealing lip 32, which are integral with one another.
• the sealing lip 32 strives on an axial side from the sealing body 31 approximately in the shape of a truncated cone and is elastically movable relative to the sealing body 31.
• the sealing element 30 is tensioned on the shaft 10 or on the sleeve 18 and held in an elastically clamping manner.
• the radial dimensioning of the sealing element 30 is selected such that the sealing element 30 seals the passage 19 of the base part 17 with respect to the dust chamber 15.
• the sealing element 30 rests elastically on the bottom part 17 with its axial side facing the bottom part 17.
• the sealing lip 32 projects in the direction of the base part 17 and its surface 22, the sealing lip 32 preferably bears against the surface 22 of the base part 17 with a slight pretension. In this way, there is at least a slight contact pressure of the sealing lip 32. Due to the mobility of the sealing lip 32, tolerances, misalignments, angular deviations or the like, in particular of the base part 17, are compensated for by this.
• the sealing lip 32 provides a good seal in the axial direction, namely a sealing of the bearing 13 in relation to the dust chamber 15. When the shaft 10 rotates, the sealing lip 32 is relieved somewhat by the centrifugal force, as a result of which the friction at the contact point with the base part 17 and thus the wear of the sealing lip 32 is reduced.
• the housing part 12 is preferably made of light metal and in particular of die-cast aluminum.
• the surface 22 of the base part 17 which is in contact with the flexible sealing lip 32 is untreated, for example. machined cast iron. This surface 22 does not have to be polished. It is advantageous if the surface 22 is only greased, as a result of which the friction in the region of the contact surface with the sealing lip 32 is reduced.
• a good seal of the bearing 13 to the dust chamber 15 is achieved in the manner described by the axial sealing element 30, and this in a simple and inexpensive manner, in particular when axial sealing elements 30 as components in this form are already commercially available and available.
• the bearing 13, in particular deep groove ball bearing, has sealing disks 23 and 24 integrated therein on both sides, only schematically indicated in FIG. 2, which are seated, in particular, on the outer ring 20 and with respect to the axial end face 25 or 26 of the inner ring 21 further inside and at a distance run away.
• a disk 27, for example is made of thin sheet rotatably arranged, which rotates with the shaft 10.
• the disk 27 lies against the facing end face 26 of the inner ring 21 and radially covers the integrated sealing disk 24 with at least a small axial distance, so that there is no friction between the rotating disk 27 and the non-rotating sealing disk 24.
• the disk 27 acts as a centrifugal disk, which is sufficient for axially sealing the bearing 13 on this side.
• the shaft 10 On the axial side of the fan wheel 14 facing away from the axial sealing element 30, the shaft 10 carries, for example, an eccentric sleeve 40, on which the grinding plate 11 is rotatably mounted by means of an associated, sleeve-shaped inner ring 41 via a bearing 42.
• the bearing 42 of the grinding plate 11 is formed from an open needle sleeve and axially sealed on the axial side facing the fan wheel 14 by means of at least one sealing element 43, which is effective between the grinding plate 11 and the sleeve-shaped inner ring 41.
• the sealing element 43 is designed as a radial shaft sealing ring, two identical radial shaft sealing rings being provided in the exemplary embodiment shown, which are axial are arranged one behind the other.
• the at least one sealing element 43 is designed as a sealing ring with a cross-section that is approximately U-shaped and has two striving sealing lips, one of which functions as a sealing lip and the other as a dust lip.
• the bearing 42 is sealed in a simple manner by the at least one sealing element 43 at the area facing the fan wheel 14 in relation to the dust chamber 15 and the dust accumulating there.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Sealing Of Bearings (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)
• Grinding-Machine Dressing And Accessory Apparatuses (AREA)

Priority Applications (3)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26034371

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (4)

Citations (6)

• 1998
  • 1998-01-16 JP JP53714498A patent/JP2001513032A/ja active Pending
  • 1998-01-16 WO PCT/DE1998/000136 patent/WO1998038014A1/de active IP Right Grant
  • 1998-01-16 CN CN98802866A patent/CN1077833C/zh not_active Expired - Lifetime
  • 1998-01-16 EP EP98906813A patent/EP0963278B1/de not_active Expired - Lifetime

Patent Citations (6)

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