Machine tool, especially a hammer drill or chisel

Information

  • Patent Grant
  • 6464234
  • Patent Number
    6,464,234
  • Date Filed
    Thursday, January 11, 2001
    23 years ago
  • Date Issued
    Tuesday, October 15, 2002
    22 years ago
Abstract
The machine tool, especially a hammer drill or chisel, has a rotatable and/or axially movable tool holder (10,12) for a tool (16) having a grooved shaft. The tool holder (10,12) includes a base body (22); two radially movable locking bodies (18,20) held in the base body and movable into respective locking positions engaged in two closed grooves (26,28) in the tool shaft; a bearing member (32) movable between a bearing position for holding the locking bodies (18,20) in the locking position and a releasing position in which the locking bodies are movable out of the grooves; an operating member (36,38) connected with the bearing member (32) for moving the bearing member (32) and a resilient plastic guiding member (42,44) arranged to guide the locking bodies (18,20) radially outward during motion from the locking to unlocking position and to act on the locking bodies (18,20) with a radially inwardly directed spring force.
Description




BACKGROUND OF THE INVENTION




The present invention relates to a machine tool, especially a hammer drill or chisel hammer or chipping hammer, and, more particularly, to a machine tool having a rotatably driven and/or hammering tool holder for receiving a tool with a grooved shaft, which has a base body with at least one radially movable locking body, which engages in a closed groove in one end of a shaft of a tool held in the tool holder and which is retained in a locking position by a releasable bearing member, which may be moved into a releasing position in which the locking body is radially released so that it can move into its unlocking position by means of an operating element.




A hammer drill machine with a rotatably driven tool holder is disclosed in EP 0 456 003 B1. The tool holder has a base body and a receptacle arranged in it for a drill or a hammer tool, in which a chuck with jaws acting as a first tool-holding means and a special second tool-holding means for a tool provided with a grooved shaft are arranged. The special second tool receptacle has a radially slidable locking element in the form of a locking ball, which is movable into a closed groove on a shaft end of the tool and which is held in its locking position by a retaining or bearing sleeve and a locking sleeve having limited axial movability. The locking sleeve is spring-loaded so as to be urged over the retaining sleeve in the direction of its holding position. In the locking position of the locking ball the locking sleeve radially overlaps the locking ball and the retaining sleeve locks the locking ball with an axially projecting portion.




When the tool is inserted the locking ball is pushed into a longitudinal slot in the insertion direction by the shaft end of the tool. Thus the projecting portion of the retaining sleeve is pushed against the spring by means of the locking ball. A free space, in which the locking ball can escape radially to the outside, arises between the locking sleeve and the retaining sleeve. The tool can be inserted. Subsequently the pre-compressed spring slides the locking sleeve into its initial position and presses the locking ball in the grove of the tool.




To take the tool out of the tool holder the locking sleeve is pushed against the retaining sleeve with an operating element and against the spring loading the retaining sleeve, so that the locking ball can radially escape to the outside and the tool can be removed. After that the spring forces the retaining sleeve, the locking sleeve and the locking ball back into their initial position.




SUMMARY OF THE INVENTION




It is an object of the present invention to provide an improved machine tool.




This object, and others which will be made more apparent hereinafter, are attained in a machine tool having a rotatably driven and/or axially movable tool holder for receiving a tool with a grooved shaft, which comprises a base body with at least one radially movable locking body, which engages in at least one closed groove in one end of a shaft of a tool held in the tool holder and which is retained in a respective locking position by a releasable bearing member, which may be moved into a releasing position, in which the locking member is radially released, by means of an operating member.




According to the invention the tool holder has a guiding member arranged to guide the at least one locking body radially outward during motion from the locking to the unlocking position when the releasable bearing member is in the releasing position. The guiding member acts on the at least one locking body under a radially inwardly directed spring force. Tipping and tilting of the at least one locking body is thus prevented by the guiding spring force and axial motion of the at least one locking body is not required.




In preferred embodiments of the invention the radially inwardly directed spring force can be produced by one or more separate spring elements acting on the guiding member. Advantageously in a particularly preferred embodiment the guiding member or structural element is elastically deformable or resilient. The required spring force can then be produced at least partially, preferably completely, by the guiding member itself. These preferred embodiments have a reduced number of components, take up less space and have reduced assembly costs in comparison to other embodiments.




The guiding member can comprise any of a number of different elastic materials, which appear to be significant to one skilled in the art. These elastic materials include metal and plastic. The plastic guiding members, however, are particularly light and economical.




Furthermore the guiding member can have a variety of different shapes. For example, it can be ring-shaped, bar-shaped, etc, and can be compressible rubber packing, an elastic rubber or plastic bar, etc. If the guiding member is in the form of a sleeve, it can be easily assembled because of its rotational symmetry. Assembly errors can thus be avoided.




In order to save space and additional components, the operating member is guided in its motion by means of the guiding member and/or the guiding member is made in one piece with the operating member.




The locking bodies can have different shapes. For example, they can be square, spherical or take some other shape that appears significant to one skilled in the art. However if the locking body is shaped like a roll or roller, economical standardized parts result. Rolls or rollers have large transmission surfaces in their rotation directions. Torque transmission elements can be replaced or at least advantageously assisted by the rolls or rollers.




In a particularly preferred embodiment of the invention at least one portion of the tool holder is mounted axially slidable for producing an idle connection or drive connection and the locking body has a length substantially equal to that of the groove in the tool. By guiding the locking body by means of the spring force the locking body advantageously can be guided radially to the outside without axial motion. The locking body can have the maximum length and a maximum torque transmission can be obtained from this locking body. Large transmission surfaces in the rotation direction, small surface pressing values, smaller wear and longer service life can be attained for the locking body and the torque transmission elements.











BRIEF DESCRIPTION OF THE DRAWING




The objects, features and advantages of the invention will now be illustrated in more detail with the aid of the following description of the preferred embodiments, with reference to the accompanying figures in which:





FIG. 1

is a longitudinal cross-sectional view through a first embodiment of a tool holder according to the invention in a locked state,





FIG. 2

is a longitudinal cross-sectional view through the tool holder shown in

FIG. 1

in an unlocked state;





FIG. 3

is a longitudinal cross-sectional view through a second embodiment of a tool holder according to the invention in a locked state; and





FIG. 4

is a longitudinal cross-sectional view through the tool holder shown in

FIG. 3

in an unlocked state.











DESCRIPTION OF THE PREFERRED EMBODIMENTS





FIG. 1

shows a rotatably driven and/or axially movable tool holder


10


of a hammer drill for receiving a tool


16


, which has a base body


22


with two radially slidable locking rollers


18


,


20


, which are arranged in cavities


24


,


34


in the base body


22


and are guided in respective closed grooves


26


,


28


in one shaft end of the tool


16


. So that the locking rollers


18


,


20


do not fall radially inwardly out from the cavities


24


,


34


when the tool


16


is not present, the cavities


24


,


34


are tapered or narrowed in radially inward directions.




The locking rollers


18


,


20


are held in locking positions by a bearing member or sleeve


32


made from metal when the bearing sleeve


32


is in its holding or retaining position shown in FIG.


1


. The bearing sleeve


32


is connected in an axial direction with a plastic operating sleeve


36


fitting together with it in a form-locking manner. A coil spring


52


, which is braced via a ring element


48


on a shoulder


50


of the base body, which holds the bearing sleeve


32


in its holding or retaining position by means of the operating member or sleeve


36


, acts on the operating sleeve


36


(FIG.


1


). The operating sleeve


36


is braced or bears on a rubber cap


46


in the axial direction remote from the coil spring


52


. The rubber cap


46


is attached to the base body


22


in a portion or part


14


of the base body in which the tool


16


is inserted.




The bearing sleeve


32


is movable axially by means of the operating sleeve


36


into a releasing position (

FIG. 2

) in which the locking rollers


18


,


20


are radially released or freed so that that they can be disengaged from the closed grooves in the shaft of the tool


16


. Indeed the operating sleeve


36


is pushed axially against the action of the coil spring


52


in a direction away from the part or portion


14


of the base body in which the tool is inserted (FIG.


2


). The tool


16


can then be guided into or removed from the tool holder


10


when the bearing sleeve


32


is in the position radially releasing or freeing the locking rollers


18


,


20


.




According to the invention the locking rollers


18


,


20


are radially movable toward the outside against a high temperature-resistant resilient plastic sleeve


42


, which is made from an elastomeric material, by moving the tool


16


when the bearing sleeve


32


is in the releasing position in which the locking rollers


18


,


20


are radially released. In this embodiment the plastic sleeve


42


is the guiding member. The resilient plastic sleeve


42


urges the locking rollers


18


,


20


radially inward with a spring force produced by compression and guides the locking rollers


18


,


20


in their motions inward and outward. The resilient plastic sleeve


42


is attached to the operating sleeve with a ring-shaped projecting portion


30


at its end closest to the part


14


of the base body in which the tool is inserted. The resilient plastic sleeve


42


is located in an appropriately shaped interior cavity


40


of the operating sleeve


36


.




The locking rollers


18


,


20


are continuously oriented with their body axes parallel to the tool axis during their motion in the radial direction. The locking rollers


18


,


20


are moved exclusively radially during the locking and unlocking process, i.e. without tilting or tipping. The operating sleeve


36


is guided in its axial motions by means of the resilient plastic sleeve


42


.




An additional alternative embodiment of the tool holder.


12


is shown in

FIGS. 3 and 4

. Parts in the embodiment of

FIGS. 3 and 4

, which are essentially the same as the parts shown in

FIGS. 1 and 2

, are given the same reference numbers in

FIGS. 3 and 4

. In the following the differences between the embodiments of

FIGS. 1 and 2

and

FIGS. 3 and 4

are pointed out. Reference is made to the description of

FIGS. 1 and 2

for functions, which are the same.




The tool holder


12


shown in

FIGS. 3 and 4

has a resilient plastic sleeve


44


, which forms a front portion of the operating sleeve


38


and by which the operating sleeve


38


is braced in an axial direction on the rubber cap


46


. The plastic sleeve


44


is attached to an axially facing side of the operating sleeve in a form-closed and material-connected manner. In other words, in this latter embodiment the operating sleeve and the guide member are in one piece.




The disclosure in German Patent Application 100 01 191.8-15 of Jan. 14, 2000 is incorporated here by reference. This German Patent Application describes the invention described hereinabove and claimed in the claims appended hereinbelow and provides the basis for a claim of priority for the instant invention under 35 U.S.C. 119.




While the invention has been illustrated and described as embodied in a machine tool, especially a hammer drill or chisel, it is not intended to be limited to the details shown, since various modifications and changes may be made without departing in any way from the spirit of the present invention.




Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.




What is claimed is new and is set forth in the following appended claims.



Claims
  • 1. A machine tool comprising a movable tool holder (10,12), said tool holder comprising means for receiving and holding a tool (16) having a grooved shaft provided with at least one closed groove, wherein said tool holder (10,12) includinga base body (22); at least one radially movable locking body (18,20) held in said base body (22) so as to be movable between a locking position, in which said at least one radially movable locking body is engaged in said at least one closed groove (26,28) provided in said grooved shaft of said tool (16), so that the tool (16) is retained in said tool holder (10,12), and an unlocking position, in which said at least one radially movable locking body is disengaged from said at least one closed groove (26,28), so that the tool (16) is removable or insertable in said tool holder (10, 12); a releasable bearing member (32) movable between a bearing position for holding said at least one radially movable locking body (18,20) in said locking position and a releasing position for releasing said at least one radially movable locking body (18,20) from said locking position, so that said at least one radially movable locking body (18,20) is movable from said locking position to said unlocking position an operating member (36,38) connected with said bearing member (32), said operating member (36,38) comprising means for moving said releasable bearing member (32) between said bearing position and said releasing position; and a guiding member (42,44) arranged to guide said at least one locking body (18,20) radially outward during motion from said locking to said unlocking position when said releasable bearing member (32) is in said releasing position and to act on said at least one locking body (18,20) under a radially inwardly directed spring force.
  • 2. The machine tool as defined in claim 1, wherein said guiding member (42,44) is elastically deformable or resilient and provides at least a portion of said radially inwardly directed spring force.
  • 3. The machine tool as defined in claim 1 or 2, wherein said guiding member (42,44) is plastic.
  • 4. The machine tool as defined in claim 1, wherein said guiding member (42,44) is a sleeve.
  • 5. The machine tool as defined in claim 1, wherein said guiding member (42,44) is a resilient plastic sleeve arranged between the operating member (36,38) and the base body (22).
  • 6. The machine tool as defined in claim 1, wherein said guiding member (42,44) is connected with said operating member (36,38) so that said guiding member (42,44) is guided during motions thereof by said operating member.
  • 7. The machine tool as defined in claim 1, wherein said guiding member (42,44) is in one-piece with said operating member (36,38).
  • 8. The machine tool as defined in claim 1, wherein said at least one locking body (18,20) consists of at least one roller.
  • 9. The machine tool as defined in claim 1, wherein said at least one locking body (18,20) consists of two rollers and said two rollers are arranged on opposite sides of said base body respectively.
  • 10. The machine tool as defined in claim 1, consisting of a hammer drill.
  • 11. The machine tool as defined in claim 1, consisting of a hammer chisel or chipping hammer.
Priority Claims (1)
Number Date Country Kind
100 01 191 Jan 2000 DE
US Referenced Citations (6)
Number Name Date Kind
1346341 Schinkez Jul 1920 A
1618851 Thurnberg et al. Feb 1927 A
4878679 Plank et al. Nov 1989 A
5709391 Arakawa et al. Jan 1998 A
20010013682 Frauhammer et al. Jan 2001 A1
20010017447 Baumann et al. Feb 2001 A1
Foreign Referenced Citations (8)
Number Date Country
3419465 Nov 1985 DE
35 16 541 Nov 1986 DE
3828309 Feb 1990 DE
197 55 364 Jun 1998 DE
0 456 003 Feb 1995 EP
1193303 Nov 1959 FR
1105878 Jul 1984 SU
1138795 Feb 1985 SU