Abstract:
The invention is based on a hand power tool, in particular a drilling- and/or chipping hammer, having a machine housing ( 12 ), a tool guiding element ( 16; 54 ), a hammer tube ( 14; 52 ), and a safety catch ( 32 )—fixed in the housing in stationary fashion in the axial direction—for a striker ( 24 ) that can be driven by means of a drive piston ( 22 ) and that is actively joined with a tool ( 20 ) situated in a tool guiding element ( 16; 54 ). 
     It is proposed that the tool guiding element ( 16; 54 ) is designed to be axially displaceable in relation to the machine housing ( 12 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention is based on a hand power tool, in particular a drilling-and/or chipping hammer. 
     A hand power tool of this type is known in practice and is developed as a drilling hammer, for example, that comprises a hammer tube situated in a machine housing, in which said hammer tube a drive piston developed as a pot-type piston is guided. The pot-type piston is coupled via an air cushion with a “striker” which, in turn, is actively connected with a punch dolly for driving a tool situated in a tool guiding element, which said tool is developed as a drill bit, for example. “Drive teeth” with which the tool meshes are formed on the tool guiding element. 
     The drilling hammer has an idle position and an operating/striking position. In the idle position, the tool, the punch dolly, and the striker are situated in a “forward” position. The striker is held by a safety catch. In the operating position, in which the tool is placed on a surface to be worked, for example, the tool is subjected to axial pressure, so that the entirety composed of the tool, the punch dolly, and the striker are moved into a “rear” position, and “idle openings” in the pot-type piston are closed by the striker. As a result, a compressed air cushion forms between the pot-type piston and the striker, by means of which movement of the pot-type piston is transferred to the striker and, therefore, to the punch dolly and the tool. 
     In the case of the known drilling hammer, the tool guiding element and the safety catch are each fixed in stationary fashion in the housing in the axial direction, so that, during transition from the idle position to the operating position, or from the operating position to the idle position, relative motion takes place between the tool guiding element and the tool. 
     SUMMARY OF THE INVENTION 
     The invention is based on a hand power tool, in particular a drilling- and/or chipping hammer, having a machine housing, a tool guiding element, a hammer tube, and a safety catch—fixed in stationary fashion in the housing in the axial direction—for a striker that can be driven by means of a drive piston and that is actively joined with a tool situated in the tool guiding element. 
     It is proposed that the tool guiding element is designed so that it is axially displaceable in relation to the machine housing. During transition from the idle position to the operating position, or from the operating position to the idle position, axial displacement of the tool and axial displacement of the tool guiding element can take place. The relative motion between the tool and the tool guiding element can be kept to a minimum. Operation-induced wear in the joint region between these two components is therefore minimal which, in turn, results in a long service life of the components. In particular when the tool guiding element is turnably supported and comprises drive teeth for the tool, a large tooth contact surface area can be realized between the tool and the tool guiding element in the direction of rotation. This results in a slight surface pressure, which, in turn, has a favorable effect on wear. 
     A compression spring is a cost-effective means for setting the idle position of the tool guiding element, by means of which the tool guiding element is preloaded in the direction of the tool. 
     According to a preferred embodiment of the hand power tool according to the invention, the tool guiding element is designed integral with the hammer tube. This results in a reduced number of components and, therefore, to reduced installation expense. The assembly comprising the tool guiding element and the hammer tube is then designed to be axially displaceable, so that, during transition from the idle position to the operating position, or from the operating position into the idle position, the hammer tube also undergoes axial displacement. In this exemplary embodiment, the compression spring can act directly on the hammer tube or on the tool guiding element. 
     In order for the safety catch to follow a rotation of the tool guiding element or the hammer tube, the safety catch is advantageously supported in a guide ring fixed in the housing in stationary fashion. Particularly when the tool guiding element and the hammer tube are designed as a single component, the safety catch is supported axially in the housing in stationary fashion, without negatively affecting the rotation of the hammer tube. 
     A pin associated with the safety catch and that meshes with the guide ring is a structurally simple means of attaining the object for guiding the safety catch in the guide ring. In order to drive the pin when the hammer tube rotates, said pin advantageously passes through a slot in the hammer tube that extends in the axial direction. 
     In the case of an alternative exemplary embodiment, in which the tool guiding element and the hammer tube are designed as at least two components, the safety catch can be fastened to the hammer tube that is joined with the machine housing. In this exemplary embodiment, the hammer tube and the safety catch are fixed in the housing in stationary fashion in the axial direction. The tool guiding element can be replaced individually if it becomes worn. 
     In order to obtain a good start-up behavior of the hand power tool according to the invention, the drive piston is advantageously designed as a pot-type piston. This is of particular advantage in the case of heavy drilling- and/or chipping hammers. It is also feasible, however, to design the drive piston as a cylindrical piston. 
     So that the striker is always guided securely in the pot-type piston, the safety catch can extend into the pot-type piston. In this case, the safety catch serves as a stop for the striker when it is displaced in the pot-type piston. 
     Further advantages result from the following description of the drawing. Exemplary embodiments of the invention are presented in the drawings. The drawings, the description, and the claims contain numerous features in combination. One skilled in the art will advantageously consider them individually as well and combine them into reasonable further combinations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a schematic longitudinal view through a drilling hammer in the operating position, 
     FIG. 2 shows the drilling hammer according to FIG. 1 in the idle position, 
     FIG. 3 shows a schematic longitudinal view through an alternative exemplary embodiment of a drilling hammer in the operating position, and 
     FIG. 4 shows the drilling hammer according to FIG. 3 in the idle position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A schematic drawing of a drilling hammer  10  is shown in FIGS. 1 and 2 that is capable of being driving by a not-further-shown electric motor and that comprises a “pot-type piston striking mechanism”. FIG. 1 shows the drilling hammer  10  in the operating position, i.e., in the striking position, and FIG. 2 shows the drilling hammer  10  in the idle position. 
     The drilling hammer  10  comprises a machine housing  12  in which a hammer tube  14  is supported in axially moveable and turnable fashion, which said hammer tube is designed integral with a tool guiding element  16 . The anterior region of the hammer tube  14  is supported via a sliding bearing  48  in the housing  12 . Drive teeth  18  for an impact drilling tool  20  are developed on the tool guiding element  16 , which is designed to be axially displaceable. The hammer tube  14  and, therefore, the tool guiding element  16 , are turnably supported in the machine housing  12 . 
     A pot-type piston  22 , a striker  24 , and a punch dolly  26  are guided in the hammer tube  14  in known fashion. The punch dolly  26  serves to transfer pulses to the tool  20 . The axial motional play of the punch dolly  26  is limited by means of a rubber O-ring  30  bearing against an end bearing  28 , which said O-ring serves to drive the hammer tube  14  when pressure is exerted axially on the tool  20  in the direction of the pot-type piston  22 , so that the punch dolly  26  is displaced by the tool  20 , and the hammer tube  14  and/or the tool guiding element  16  is displaced via the O-ring  30  by the punch dolly  26  in the direction of the pot-type piston  22 . In the operating position, the punch dolly  26  is pressed against the O-ring  30 , as shown in FIG.  1 . 
     In order to hold the striker  24  in the idle position shown in FIG. 2, a safety catch  32  is further equipped with a catch ring  34  inside the hammer tube  14 , which said safety catch extends into the pot-type piston  22  on its open side in the axial direction, and interacts with a ring collar  36  of the striker  24 . The safety catch  32  is fixed in the housing in stationary fashion in the axial direction. The safety catch  32  encloses a straight pin  38  that passes through an axially-positioned slot  40  in the hammer tube  14  and engages with a guide ring  42  acting as support for the safety catch  32 , which said guide ring is fastened to the machine housing  12 . When the hammer tube  14  rotates, the straight pin  38  is guided in the guide ring  42  in the circumferential direction. 
     A compression spring  44  acts on the guide ring  42 , which said compression spring acts on the hammer tube  14  via an end bearing  46  and preloads it in the direction of the tool  20 , i.e., in the idle position. The end bearing  46  is moveably supported in the circumferential direction in an annular groove of the hammer tube  14  and is fixed in the housing in stationary fashion in the circumferential direction in relation to the machine housing  12 . 
     A chipping hammer  50  is shown in FIGS. 3 and 4. Components that are essentially the same are labelled with the same reference numerals in the exemplary embodiments. Moreover, the description of the exemplary embodiment according to FIGS. 1 and 2 can be referred to with regard for identical features and functions. 
     The chipping hammer  50 , the operating position of which is shown in FIG. 3, and the idle position of which is shown in FIG. 4, differs from the drilling hammer according to FIGS. 1 and 2 in that it has a hammer tube  52  and a tool guiding element  54  that are developed as two components. Moreover, the chipping hammer  50  does not have a rotary actuator of the tool guiding element  54  and/or the hammer tube  52 . 
     A safety catch  32  with a catch ring  34  is fastened to the inner wall of the hammer tube  52 , which said safety catch interacts with a ring collar  36  of a striker  24 . The hammer tube  52  is permanently joined with a machine housing  12  via a connecting element  56 , so that the safety catch  32  is fixed in the housing in stationary fashion in the axial direction. 
     A compression spring  44  that bears against an end bearing  46  supported in an annular groove of the tool guiding element  54  and preloads the tool guiding element  54  in the direction of the idle position acts on the connecting element  56 . 
     The tool guiding element  54  is guided in the hammer tube  52  in axially moveable fashion and is therefore designed to be axially displaceable in relation to the machine housing  12 . The axial motional play of the tool guiding element  54  in relation to the hammer tube  52  is determined by a longitudinal groove  60  that is developed in the outer wall of the tool guiding element  54 , and in which a ball  58  engages that is held in a through hole in the hammer tube  52 . The through hole is covered radially outwardly by the connecting element  56 . 
     A punch dolly  26  is guided in the tool guiding element  54 , which said punch dolly interacts via drive teeth  18  with a tool  20  fastened in the tool guiding element  54 , and with an O-ring  30  bearing against an end bearing  28  to displace the tool guiding element  54  in the axial direction. The punch dolly  26  can be operated by means of the striker  24  driveable via a pot-type piston  22 . Instead of that which is shown in the exemplary embodiments, the hammer tube and the tool guiding element could also be developed as two components in the case of a drilling hammer and, in the case of a chipping hammer, the hammer tube and the guiding element could be developed as a single component. 
     Reference Numerals 
       10  Drilling hammer 
       12  Housing 
       14  Hammer tube 
       16  Tool guiding element 
       18  Drive teeth 
       20  Tool 
       22  Pot-type piston 
       24  Striker 
       26  Punch dolly 
       28  End bearing 
       30  O-ring 
       32  Safety catch 
       34  Catch ring 
       36  Ring collar 
       38  Straight pin 
       40  Slot 
       42  Guide ring 
       44  Compression spring 
       46  End bearing 
       48  Sliding bearing 
       50  Chipping hammer 
       52  Hammer tube 
       54  Tool guiding element 
       56  Connecting element 
       58  Ball 
       60  Longitudinal groove