Abstract:
A power tool has a housing, a tool, in particular a metal-cutting tool, and a guard embracing the tool that is coupleable to the housing and axially adjustable relative, so that it is safer to handle because the guard is designed as a support foot and on its outside has a jacket piece of plastic with a nonslip, rough outer surface.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is based on a power tool.  
         [0002]     From German Patent DE 196 37 690 C2, a power tool designed as a top spindle molder with cutting depth adjustment is known, which permits relatively safe, convenient adjustment of the cutting depth, but a continuously variable manual rapid adjustment is not possible, and the grip region of the support foot, while it is of plastic and is nonslip, is nevertheless markedly less stable than a support foot of that kind of metal, such as aluminum.  
       SUMMARY OF THE INVENTION  
       [0003]     Accordingly, it is an object of the present invention to provide a power tool which eliminates the disadvantages of the prior art.  
         [0004]     In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a power tool, comprising a housing; a tool; guard means embracing said tool, said guard means being couplable to said housing and axially adjustable relative to said housing, said guard means being configured as a support foot and composed of metal, said guard means on an outside having a substantially congruent jacket piece composed of non metal.  
         [0005]     When the power tool is designed in accordance with the present invention, it has the advantage that a top spindle molder has thus been created whose support foot unites the stability of a metal construction with the nonslip nature of a soft plastic, and both the attainable work precision and the fast and precise adjustment of the cutting depth can be made in a way that is safely checkable, and the means provided for that purpose are simple to manufacture and install as well as being economical, sturdy, and easy to operate.  
         [0006]     Because the adjusting positions between the housing and the guard means can be changed quickly, safe, precise fine adjustment of the cutting depth position is possible immediately after a quick coarse adjustment has been done.  
         [0007]     Because the adjusting positions between a coarse and a fine adjustment can be changed between the housing and the guard means by means of a relative rotation, the cutting depth adjustment can be done especially simply and in a time-saving way.  
         [0008]     Because the guard means is designed as a support foot which annularly embraces the housing and can be switched over into two defined rotary positions, which define a fine adjustment stage and a coarse adjustment stage for changing the axial position of the housing relative to the support foot, a simple, operationally safe switchover of the power tool in the cutting depth adjustment is possible.  
         [0009]     Because the two rotary positions are defined, overlooking immediately adjacent to one another, with minimal rotary travel of the housing relative to the support foot, the rotary position can be adjusted in a way that can be quickly changed.  
         [0010]     Because overlooking means between the housing and the support foot make every change in the adjustment stage audible and perceptible by touch, they secure these parts against being changed unintentionally.  
         [0011]     Because the housing has a steplike collar onto which the support foot can be slipped, and the outer contour of the housing makes a smooth transition to the outer contour of the support foot that has been slipped all the way on, and in this position of the housing relative to the support foot the minimum telescopic extension position and hence a maximum cutting depth for the tool is set, the mutual rotation of the support foot and the housing in the transition region between them can be sensed safely and monitored by the user&#39;s hand in the switchover process.  
         [0012]     Because there is a depth stop between the housing and the support foot, which stop in the first adjustment stage does not engage the space between the housing and the support foot but does adjustably engage in the second adjustment stage, an axial coarse adjustment stage of the housing relative to the support foot is possible in the first adjustment stage, and from that adjustment, after switchover to the second adjustment stage, the final cutting depth can be finely set by rotating the depth stop.  
         [0013]     Because the depth stop is designed as a screw bolt, on one end of which an adjusting wheel is seated in a manner fixed against relative rotation, with which adjusting wheel the depth stop is located, drivable to rotate but axially secured, in the support foot, the depth stop, in the fine adjustment stage, by rotation by hand, can adjust the housing axially finely relative to the support foot, and in the first adjustment stage it remains without engagement with the housing, and moreover upon release of the housing from the support foot can remain secured in the support foot against being lost.  
         [0014]     Because the adjusting wheel passes through the support foot to the outside in a way that can be operated by hand, and the screw bolt rests longitudinally parallel in a groove in an inside of the wall of the support foot in a form-locking way over approximately half the length and, with its protruding longitudinal region on the diametrically opposite side is associated with a parallel outer longitudinal housing groove, the depth stop can be adjusted from outside especially safely—without the risk of injury to the hand of the user by the tool.  
         [0015]     Because, next to the one longitudinal housing groove, there is a further longitudinal housing groove, in particular with a female thread, which fits the thread of the depth stop and into which the screw bolt can be placed longitudinally when it is placed in the one longitudinal housing groove, fine adjustment of the housing relative to the support foot is possible, and upon placement in the other longitudinal housing groove, a free axial adjustment of the housing relative to the support foot is possible by hand.  
         [0016]     Because the center spacing of the longitudinal housing groove is less than the groove diameter, the switchover travel distance for changing the adjustment stages is especially short.  
         [0017]     Because between the longitudinal housing grooves, at the transition from one to the other, overlooking means are provided which positionally secure the screw bolt in an overlooking fashion in its respective longitudinal housing groove, an unintentional change of the adjustment stages is precluded.  
         [0018]     Because one of the longitudinal housing grooves has fitting thread means that are capable of engaging the screw bolt, a replicable fine adjustment of the housing relative to the support foot is possible upon rotation of the screw bolt by way of actuation of the adjusting wheel.  
         [0019]     Because the other of the longitudinal housing grooves embraces the screw bolt with radial play without engagement, in the second adjustment stage the housing can be easily adjusted freely axially relative to the support foot between the two end points of the axial position, by quasi-free axial displacement.  
         [0020]     Because as the overlooking means between the longitudinal housing grooves, a parallel bolt seeks to be braced in spring-prestressed fashion radially movably outward, that is, longitudinally toward the support foot counter to the screw bolt of the depth stop, a large-area, safe to use overlooking means between the support foot of the housing is created.  
         [0021]     Because the collar of the housing and/or the upper edge, which can be braced on it, of the sleevelike shaft of the support foot extends obliquely, the correct reinsertion of the housing into the support foot after they have been manipulated separately is safe to use. Because the adjusting positions are releasably lockable, in particular by clamping means, and thus can be defined axially and radially, the cutting depth of the power tool can be set in an assured way.  
         [0022]     Because the support foot is dimensioned such that the power tool can be set with its help freely standing on a horizontal, level surface, especially precise, tilt-proof work with the power tool is possible.  
         [0023]     Because the housing is limited relative to the support foot in its axial end positions upon longitudinal displacement by means of stops, in particular by a bayonet mount, unintentional release or loss of the support foot from the housing and vice versa is precluded.  
         [0024]     Because scale means for monitoring the cutting depth are located between the housing and the support foot, their cutting depth position, particularly in the fine adjustment stage, can be safely controlled and adjusted replicably.  
         [0025]     Because the power tool is designed as a top spindle molder, and the various set positions each correspond to a certain cutting depth, the power tool can be adjusted and safely handled in an especially time-saving way.  
         [0026]     Because the adjustment means, described above in terms of their advantages, serve to vary or fix two parts, telescoping one inside the other, relative to one another, it can also be used especially advantageously—with its own inventive importance—in still other kinds of application than-in power tools, in which both fast and especially precise setting of the relative position is necessary.  
         [0027]     The invention is described in further detail below in terms of one exemplary embodiment, in conjunction with the drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1  shows the power tool from the front;  
         [0029]      FIG. 2  shows the power tool from the left;  
         [0030]      FIG. 3  shows the support foot and the power tool in an exploded view, axially taken apart;  
         [0031]      FIG. 4  shows the power tool without the support foot and with the depth stop;  
         [0032]      FIG. 5  shows the support foot from above with the depth stop;  
         [0033]      FIG. 6  is an enlarged cross section between the support foot and the housing with the depth stop, in the fine adjustment stage;  
         [0034]      FIG. 7  is the same view as  FIG. 6 , in the coarse adjustment stage;  
         [0035]      FIG. 8  is a further side view of the housing;  
         [0036]      FIG. 9  is an exploded view of the support foot; and  
         [0037]      FIG. 10  is an exploded view of the support foot with the jacket piece.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0038]     As an electrically powered top spindle molder, which comprises a housing  12  that has a push button  14  at the front for turning it on and off, and from whose lower free end  11  a rotating tool  15  for metal-cutting machining of workpieces protrudes.  
         [0039]     The cylindrical housing  12 , in the uppermost quarter of its length, has a waist  17 , which can easily be grasped with one hand and, with its radial projection conforms in an axially supportive way to the hand holding it. The lower half of the housing  12  has a slightly smaller outer diameter than the upper region, and with the smaller diameter forms a collar  20  ( FIG. 3 ), which can be slid in telescoping fashion into a hollow-cylindrical support foot  22 . The transition between the collar  20  and the upper region of the housing  12  forms a projection or an edge  200  that can be felt.  
         [0040]     This edge  200 , located between the collar  20  and the region of the housing  12  located above it and having the larger diameter, extends rearward—matching the upper edge of the support foot  22 —in a way inclined obliquely downward.  
         [0041]     From the upper housing region, an electrical connection cable  16  extends upward with a slight inclination. By means of its exiting direction and its inclination, it is kept reliably spaced apart from the point of engagement of the tool  15  with a workpiece, without hindering the work in the way that happens with cables that emerge at the top perpendicularly.  
         [0042]     The hollow-cylindrical support foot  22  has a vertical, tubular support foot wall  23 , which is longitudinally slit at the front; at the slit  27 , two lateral perforated clamping tabs  24  that protrude to the front are formed. A clamping screw  25  ( FIG. 2 ) can be inserted through these clamping tabs, transversely to the longitudinal axis of the support foot  22 . If the clamping screw is tightened, the two clamping tabs  24  move toward one another and in the process seek to close the slit  27 . In that process, they firmly clamp the collar  20  of the housing  12  that is seated in the support foot  22 —in a way that is secure against rotation and axial displacement. Thus a cutting depth of the tool  15 , once set, is securely fixed against unwanted change. The clamping screw  25  is a fast-action clamping screw with a pivot lever  30  with an eccentric region, not identified by reference numeral, of the kind known for instance for adjusting the height of bicycle saddles, and can be released and tightened by means of the pivot lever  30 . The pivot lever  30  of the clamping screw  25  is hinged against the support foot  22  in the tightened state and drawn largely into the contour of the support foot. As a result, when the user is manipulating the top spindle molder  10 , for instance when striking edges of workpieces, the pivot lever  30  is precluded from falling open.  
         [0043]     Below the clamping tabs  24 , the support foot wall  23  opens up over its entire width all the way down to the base plate  26  to form a windowlike front recess  31 . The base plate  26  on the lower end of the support foot  22  is substantially square and protrudes past the outer contour of the cylindrical support foot  22  at the sides, back and front. Its area is dimensioned such that the top spindle molder  10  with the support foot  22  can be set down, standing freely, securely and stably on a level support.  
         [0044]     The cutting depth for the tool  15  can be set in a controllable way by means of a scale  53  on the lower edge of the housing  12 ; the scale position relative to the adjacent upper edge  310  of the windowlike front recess  31  can be read off in the form of a reference edge.  
         [0045]     The base plate  26  has a vertical opening  29 , designed as a circular hole, for the passage of the tool  15  downward into a workpiece to be machined. By axial adjustment of the top spindle molder  10  or housing  12  relative to the support foot  22 , the depth to which the tool  15  plunges into a workpiece to be machined can be set.  
         [0046]     On the outside at the back and sides, the housing  12  and the support foot  22  are provided, in the grip region  18 , with uniformly distributed cup-shaped indentations  19 , which have a diameter of approximately 2 to 3 mm and improve the grip and hence safety of operation of the top spindle molder  10 . A grip region with an especially securely nonslip ribbing  260  made up of rectangular embossed features is formed on the top side of the base plate  26 .  
         [0047]      FIG. 2  shows the left-hand side of the top spindle molder  10 , in which in particular—going beyond  FIG. 1 —the obliquely upward and rearward extending electric cable  16 , the housing  12  that is ribbed transversely at the top, and the clamping tabs  24  protruding to the front are visible along with the pivot lever  30 . The grip region  18  with the cup-shaped indentations  19  and the edge  21  dropping obliquely rearward of the support foot  22 , and correspondingly the protruding edge  200  on the collar  20 , as well as the shape of the front recess  31  with the curved edge and a transition to the relatively far-forward-protruding base plate  26  can also all be seen.  
         [0048]     In the rear at the side, in the lower region of the support foot  22 , an adjusting wheel  28  can be seen, which emerges from a transverse slit  32  in the support foot wall  23  and has a threaded bolt  35  ( FIG. 3 )—not visible here—which extends in the interior between the housing  12  and the support foot wall  23  and serves as a depth stop  34  ( FIG. 3 ).  
         [0049]      FIG. 3  is an exploded view of the top spindle molder  10  positioned above the support foot  22 ; of the top spindle molder, only the lower region having the collar  20 , the lower free end  11  and the tool  15  are visible. The edge  200  between the upper region of the housing  12  and the collar  20  is clearly visible. In the case of the support foot  22 , the clamping screw  25  has been removed, to make the design of the perforated clamping tabs  24  and the slit  27  between the two clamping tabs visible. Also visible are the upper edge  21  of the support foot  22  and the transverse slit  32  for the adjusting wheel  28  in the lower region of the support foot  22 , above the base plate  26 . The depth stop  34  with the adjusting wheel  28  has been removed from its emplaced position in the inside surface of the support foot wall  23 . To that end, a retaining screw, not shown, that engages the adjusting wheel centrally from below must first be removed; in the installed position, it secures the depth stop  34  on the support foot  22  against being released unintentionally.  
         [0050]     The depth stop  34 , in its upper region, is designed as a screw bolt  35  with a thread  50 . The screw bolt  35  is provided for selective entry into a first or a second longitudinal housing groove  38 ,  40  in the outer wall of the housing  12  in the region of the collar  20 . The two longitudinal housing grooves  38 ,  40  extend parallel to the screw bolt  35 , or to its longitudinal groove  33  ( FIG. 5 ), in the inside face of the support foot wall  23 . Approximately centrally between and parallel to the longitudinal housing grooves  38 ,  40 , an overlooking bolt  36  is placed in a slit  42  in the housing wall  13  in the region of the collar  20  in such a way that it cannot fall out radially outward through the suitably narrow slit  42 ; it is kept prestressed radially outward in the slit  42  from behind by a leaf spring  37 .  
         [0051]     If the housing  12  has been inserted axially in telescoping fashion into the support foot  22  as intended, then the screw bolt  35  rests in one of the longitudinal grooves  38 ,  40 . If the housing  12  is meant to be rotated slightly relative to the support foot  22  such that the screw bolt  35  is meant to emerge laterally outward from the pair of longitudinal housing grooves  38 ,  40 , then this direction of rotation is blocked. Conversely, however, the housing  12  can be rotated counter to the force of the leaf spring  37  and of the overlooking bolt  36 ; depending on the rotation travel, the threaded bolt  34  snaps audibly into whichever longitudinal housing groove  38 ,  40  is adjacent to it. Before the housing  12  is rotated relative to the support foot  22 , the pivot lever  30  of the clamping screw  25  must be put into its release position, so that the slit  27  between the clamping tabs  24  opens, and the force lock between the support foot  22  and the housing  12 , or collar  20 , is released.  
         [0052]     The first longitudinal housing groove  38  has a thread  39  that fits the thread  50  of the screw bolt  35 . If the longitudinal housing groove  38  is in engagement with the screw bolt  35 , then upon its rotation, or the rotation of the adjusting wheel  28 , the housing  12  is axially adjusted relative to the support foot  22 . If the second longitudinal housing groove  40  is in engagement with the screw bolt  35 , then no form lock or force lock becomes operative between it and the housing  12 . As a result, in this position, the housing  12  is easily slid back and forth axially by hand relative to the support foot  22  between two defined axial end positions. In this position, a coarse preselection of the cutting depth can be done simply and quickly by axial displacement. Once the cutting depth position has been coarsely set, the housing  12  should be rotated relative to the support foot  22  such that the screw bolt  35  enters in overlooking fashion into the first longitudinal housing groove  38 , so that in that position, by rotation of the adjusting wheel  28 , the meshing threads  39 ,  50  bring about an axial transfer of force with a finely meterable longitudinal adjustment. Once the desired cutting depth position is reached, then pivoting of the pivot lever  30  into its clamping position, the housing  12  is locked relative to the support foot  22 , so that neither a rotary nor an axial motion between these two parts is possible. Thus the cutting depth position of the housing  12  relative to the support foot  22  is set. Depending on the selected cutting depth, the tool  15  protrudes more or less far outward past the lower edge of the base plate  26 , with a corresponding cutting depth, into a workpiece to be machined, onto which workpiece the base plate  26  should be placed.  
         [0053]     On the right, in the viewing direction, below the adjusting wheel  28 , a radially inward-protruding cam  57  can be seen, seated on the inside of the support foot wall  23 ; this cam is intended for securing engagement with a bayonet groove  55  ( FIG. 8 ) in the housing  12 .  
         [0054]      FIG. 4  shows a side view of the top spindle molder  10  in the region of the collar  20 , with a depth stop put in place—for purposes of demonstration—that was previously removed from its installed position in the support foot  22 . This depth stop  34  is placed in the second longitudinal housing groove  40 , without a thread, and is freely displaceable axially in it and cannot take on any locking force transfer function between the support foot  22  and the housing  12 . This demonstrates the course adjustment position, in which the housing  12  is limitedly freely displaceable relative to the support foot  22 .  
         [0055]     In the first longitudinal housing groove  38 , parallel to the second longitudinal housing groove  40 , the thread  39  is visible, which upon engagement of the depth stop  34  prevents an axial displacement between the housing  12  and the support foot  22  as a result of forces from outside exerted on these two parts, and allows axial displacement of them only by means of rotation of the adjusting wheel  28 .  
         [0056]     The other details recited in conjunction with the above drawing figures will—with reference to existing reference numerals that are the same—not be repeated again here.  
         [0057]      FIG. 5  shows the detail of the support foot  22 , in which beyond the above drawings, the depth stop  34  is shown in its emplaced position on the inside face of the support foot wall  23 , in which the screw bolt  35  rests freely rotatably with radial play but axially nondisplaceably in the longitudinal groove  33  of the support foot wall  23 . Moreover, the slit  27  between the clamping tabs  24  in the support foot  22  is clearly visible.  
         [0058]     The other details described in conjunction with the previous drawings will not be repeated here.  
         [0059]      FIG. 6  is an enlarged detail of the cross section between the support foot wall  23  and the housing wall  13  in the region of the longitudinal housing grooves  38 ,  40 , with threaded bolts  35  in place; on the opposite side, the longitudinal groove  33  is shown in the support foot wall  23 . This makes the overlooking and action positions of the screw bolt  35  clear.  
         [0060]      FIG. 7  shows the same details as  FIG. 6 , but with the housing  12  rotated relative to the support foot  22 ; the threaded bolt  35  rests in the second longitudinal housing groove  40  and makes free displacement of the housing  12  relative to the support foot  22  possible.  
         [0061]      FIG. 8  shows a further side view of the housing  12  with its collar  20 , looking toward an L-shaped bayonet groove  55 . This groove is composed of an upper, wide region  56 , which extends vertically, and a narrow, angled region  58  with which the wide region merges. As a locking or stop element, a cam  57 , which is seated on the inside of the hollow-cylindrical support foot wall  23  ( FIG. 9 ) and protrudes radially inward, engages the bayonet groove  55 .  
         [0062]     The cam  57  is brought into engagement with the bayonet groove  55  as follows: First, the housing  12  should be placed axially onto the support foot  22 . In the process, the region  58 , opening laterally downward, of the bayonet groove  55  is slipped over the cam  57  until further axial displacement of the housing  12  relative to the support foot  22  is stopped because of the fact that the cam  57  strikes against the upper groove wall  60  of the region  58 . By appropriate rotation of the housing  12  relative to the support foot  22 , the cam  57  is guided on the groove wall  60  until it reaches the upper region  56 . Once this position of the cam  57  is reached, the housing  12  is longitudinally freely displaceable relative to the support foot  22 , as long as the threaded bolt  35  at the same time rests in the second longitudinal housing groove  40 . So that the cam  57  will not hinder the adjustment of the rotary positions of the housing  12  relative to the support foot  22  and is axially freely movable in each rotary position, the upper region  56  of the bayonet groove  55  is designed to be correspondingly wide.  
         [0063]     An upper groove end  64  and a lower side wall  62  of the region  58  of the bayonet groove  55  are used for limiting the axial motion between the support foot  22  and the housing  12  and at the same determine their outermost axial end positions, and the cam  57  rests on them in the respective end position. This prevents unwanted release of the support foot  22  from the housing  12  when the clamping screw  25  is open.  
         [0064]     To facilitate the mounting of the support foot  22  on the housing  12 , arrowlike symbols, not identified by reference numerals, are stamped into the housing  12  and the support foot  22 , marking those regions of the housing that belong together or are to be aligned with one another as such in a visible way and at the same time describe a prerequisite mounting motion.  
         [0065]      FIG. 10  shows an exploded view of the support foot  22 , in which the clamping tabs  24  are clearly visible, spaced apart from one another by a longitudinal slit  27 , through which, aligned with one another a transverse bore  250  extends, through which the clamping screw  25  can be inserted, with which clamping screw the support foot  22  can be fixed relative to the housing  12  of the power tool  10 .  
         [0066]     The clamping screw  25 , on its right-hand end in the viewing direction, has a pivotably supported pivot lever  30  with an eccentric region, not identified by reference numeral, and on its left-hand end it has a threaded region, also not identified by reference numeral, onto which a threaded nut  252  can be screwed. Steel shims, not identified by reference numeral, are positioned between the pivot lever  30  and the outside of the clamping tab  24  oriented toward it and also between the threaded nut  252  and the outside of the other clamping tab  24  oriented toward it, and guard the aluminum support foot  22  against being worn down upon actuation of the clamping screw  25 . The lock nut  25  passes through circular openings  251  in the clamping tabs  240  of the jacket piece  220 .  
         [0067]     A longitudinal axis  222  is drawn centrally in the support foot  22 , and along it, a jacket piece  220  shown above the support foot  22  can be slipped onto the support foot  22 , so that its angled support tabs  240  fit over the outsides of the support tabs  24  of the support foot  22 . The jacket piece  220  is dimensioned such that its inside diameter precisely fits the outside diameter of the support foot  22 .  
         [0068]     Looking downward—as viewed from the clamping tabs  240 —the outer edges of the jacket piece  220  lead, increasing in size, radially outward, forming a front recess  310  which is congruent with the windowlike front recess  31  of the support foot  22 .  
         [0069]     Semi-oval recesses  241  are located in the region of the angled part of the clamping tabs  240  and effect a spring action of the clamping tabs  240  relative to the rest of the jacket piece  220 . The jacket piece  220  has a wall thickness of only about  1  mm and is drawn like a second skin over the support foot  22 , and in its rear region it has cuplike indentations  190 , which considerably improve the grip and the nonslip nature of the power tool  10  with the support foot  22  in the user&#39;s hand.  
         [0070]     To facilitate the mounting of the support foot  22  on the housing  12 , arrowlike symbols, not identified by reference numerals, are stamped into the housing  12  and the support foot  22  and the jacket piece  220 , marking those regions that belong together or are to be oriented with one another visibly as such and at the same time describe a mounting motion.  
         [0071]     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.  
         [0072]     While the invention has been illustrated and described as embodied in a power tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.  
         [0073]     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.