Hand-held belt sander

Information

  • Patent Grant
  • 6419569
  • Patent Number
    6,419,569
  • Date Filed
    Wednesday, September 27, 2000
    24 years ago
  • Date Issued
    Tuesday, July 16, 2002
    22 years ago
Abstract
A hand-held belt sander has a housing, an on-off switch and a power supply conductor supported by the housing, a motor and a transmission received in the housing, a sanding belt, a driving roller driven by the motor and driving the sanding belt, a sliding shoe provided with a base, a deviating roller arranged so that said sanding belt is guidable over the deviating roller and the base of the sliding shoe, a unit for centering the sanding belt, a unit for clamping the sanding belt, the deviating roller and the driving roller have different diameters so that the sanding belt is guided inclinedly, the housing being elongated and the sanding belt being guided on guiding parts which are introduced in a rear region of the elongated housing so that with together with the sanding belt in a front region of the elongated housing a centrally forwardly extending, freely projecting, wedge tip-shaped contour is formed so that the hand-held belt sander as a whole has a lance-like contour.
Description




BACKGROUND OF THE INVENTION




The present invention relates to a hand-held belt sander.




Hand-held belt sanders are known in the art. One of such hand held belt sanders is disclosed in the U.S. Pat. No. 4,694,616. It is provided with a driving roller and two deviating rollers having a substantially corresponding diameter. They guide the sanding belt over a sanding base exchangeably arranged on the device. With this device small surfaces of various profiles can be well treated. However, because of the relatively great diameter of the driving and deviating rollers of the hand-held belt sander and because of the coinciding tangential transmission between the rollers and the sanding base, corners and hollow channels are not sufficiently accessible.




The German patent document DE 02 42 26 708 discloses a stationary belt sanding machine with a sanding belt guided over at least two rollers and having a small sanding base. It is provided for sanding works, in which work pieces are to be treated only directly over the sanding belt surface in the embracing region of the rollers, in particular for the production of concave surfaces.




The German patent document DE 0S 39 19 651 discloses a handheld belt sander which in addition to the conventional substantially identical deviating and driving rollers, has a small additional deviating roller for guiding the sanding band tangentially coincidentally between the deviating roller and the sanding base. With this device, corners and hollow channels are substantially better accessible than with other handheld sanders. Since however its construction is based on the conventional handheld belt sander, its belt centering and belt tensioning can be performed in expensive way because of additional, small deviating roller.




Furthermore, the British patent document GB 962 164 discloses a handheld belt sander with the driving roller provided on its periphery with longitudinal grooves. Therefore an improved for transmission to the sanding band is obtained. The handheld belt sander is however heavy, uncomfortable, and complicated.




In the known handheld belt sanders the belt centering is performed by turning or tilting of the deviating rollers which rotate on roller or metal sliding bearings about a fixed rotary point on the roller axis. The deviating roller is mounted by screwing or safety rings on its axle. An exchange of the deviating roller is complicated. Moreover, in the known belt sanding devices the sanding band is tensioned by displacement of an operating lever which is operative for actuating the deviating rollers at the outer side of the sanding belt. However, the operating lever is difficult to axis and not easy to operate.




In belt sanders, independently from their size of the width of the belt, the sanding belt is driven through a rotatable driving roller by a frictional connection. Therefore, the force transmitted to the belt is dependent on the friction value between the inner side of the belt and the roller, as well as on the normal force of the belt on the roller, and on the embracing angle. However, in the known belt sanders these values are not sufficient.




SUMMARY OF THE INVENTION




Accordingly, it is an object of present invention to provide a handheld belt sander which avoids the disadvantages of the prior art.




In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a hand-held belt sander which has a lance-shaped contour, and in which the parts which guide the sanding band are guidingly introduced in a rear region of an elongated housing so that, together with the sanding belt they form in the front region of the housing a centrally forwardly extending, freely projecting wedge-tip shaped contour.




When the hand-held belt sander is designed in accordance with present invention, it has better handling, simplified mechanical system for manual adjustment of a belt centering, as well as is favorable as to the number of individual parts, the manufacture and mounting.




In accordance with another feature of present invention, a fork which receives the deviating roller and which is used for adjustment of the belt running can be exchangeable by a user without dismounting the parts of the device.




A further advantage of the present invention is that the belt running is centerable with a handle which surrounds the roller axis of the deviating roller at both sides and is supported in a sliding member so that it is joined through a virtual three point structure and is tiltable around it with an adjusting screw. The legs of the handle are formed as flat springs which by the screw force both fix the roller and also are used for a special position of the sliding block. The handle is supported at the rear end centrally in the sliding member, so that no high moments are produced in the lever. The small deviating rollers which are arranged in pairs near one another for the belt are composed of high-strength synthetic plastic and run with self lubrication and without additional roller or sliding bearings directly on the roller axle. A substantially simplified mounting, lower number of components, and low cost, as well as a simpler subsequent change of the deviating rollers is characteristic for the inventive solution when compared with the known solutions.




A special advantage of the inventive hand-held belt sander is that the sanding belt can be easily exchangeable by unlocking of both clamping rollers with a single lever which is easily operable and arranged outside of the device. The both clamping rollers are supported so that they are elastically coupled with one another to be outwardly radially expandable. In the locked position this provides for the elastic sufficient belt clamping. The adherence of the sanding dust is prevented by the clamping rollers. The clamping lever is designed so that both in the blocked and in the unblocked position it engages in a simple manner without additional components for arresting its rotary axle.




A further advantage is that a fixed base plate of the belt clamping mechanism and the sanding shoe, as well as other parts are held premountable before the mounting in the ridge-like manner. In addition, the base plate which works as a supporting cover has further functions such that the receipt of the roller bearing of the drive shaft which carries the driving roller and the receipt end positioning of the buffer disk. The bearing support is formed as a simple punched part for all multiple functions. Since its mounting is performed without additional parts between the sliding shoe and the housing shell, only a few individual components are and the mounting is simplified. A further advantage of the invention is that the frictional connection of the driving roller relative to the sanding belt is increased by combining the running surface of the driving roller from hard and soft material and applying grain material on the running surface, or it is provided with brushes and the normal force between the sanding belt and the driving roller is increased by forming grooves in the running layer, so that inclined small plates are formed which are placed under load and thereby increase in diameter of the roller. Furthermore, the application of a skin-like coating has the advantage that under load it rises, and an additional pressing roller is arranged, so that with no raising the clamping force of the belt is needed and the sanding belt can be finally operated.




It is also advantageous to provide a form-locking connection between the belt and the roller, by combining a perforated belt with a roller provided with pins or by profiling the lower side of the belt and the roller so that a form-locking connection is produced during roller of this parts over one another. In corresponding variants, the advantage of a form-locking drive is provided by a transmitting correspondingly high forces with relatively low belt clamping.




Therefore the sanding shoe, the drive cover, the housing and the means for belt clamping are provided with inventive features, and the sanding shoe and the drive cover form an important component of a replacement part, on which a differently equipped sanding belts or the like can be arranged.




The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a spacial view of a hand-held belt sander in accordance with one embodiment of the present invention;





FIG. 2

is a spacial, partially exploded view of a front region of the inventive hand-held belt sander with a released sanding belt;





FIG. 3

is an explosion view of the inventive hand-held belt sander;





FIG. 4

is an explosion view while





FIGS. 5-8

are side views of a transmission cover and a belt clamping axial;





FIG. 9

is a view of a front region of the hand-held belt sander from the side of the clamping and loosening lever for sanding belt exchange;





FIG. 10

is a view showing a longitudinal section of the front region of the hand-held belt sander;





FIG. 11

is a view of the front region of the hand-held belt sander from the side of the free sanding belt side;





FIGS. 12

,


13


are a longitudinal and a transverse section of the clamping and loosening lever;





FIGS. 14



a


and


14




b


are views showing a transverse crosssection of the driving roller;





FIGS. 15



a


and


15




b


are views showing a further modification of the driving roller;





FIG. 16

is a spacial view of a sliding shoe; and





FIGS. 17



a


and


17




b


are views showing an auxiliary tool for exchanging deviating rollers.











DESCRIPTION OF PREFERRED EMBODIMENTS




A hand-held belt sander


10


shown in

FIG. 1

has a slim, lance-shaped construction with forward wedge-shaped and approximately tip-shaped working surfaces of a sanding band


20


. Its housing


12


extends directly rearwardly for receiving a transmission


15


and a motor


14


shown in FIG.


3


. The elongated, rod-shaped housing


12


includes a longer and a shorter shells


112


,


212


, which are connected with one another through a central abutment joint


312


.




An on-off switch


16


is arranged in the rear region of the housing


12


for turning on the motor for rotating the sanding belt


20


. An electric cable


18


extends from the rear end of the housing


12


. Near it a suction


2101


of the suction passage


101


shown in

FIG. 3

near an adjusting gear


105


of an electronic rotary speed preselecting device. Lateral ventilation slots


106


are provided in the rear and the front region of the housing


12


. The shorter shell


212


forms relative to the longer shell


112


a recess


412


in the wedge-shaped, front region of the housing


12


. A sanding belt


20


is guided in the recess


4102


so that it substantially coincides with the contour of the elongated shell


112


as seen in the lateral direction.




The sanding belt


20


is supported by a sliding shoe


33


shown in FIG.


3


. The sliding shoe is wedge-shaped and has a tip


333


extending forwardly. The sliding shoe


33


is provided on its edge surfaces with two sanding bases


133


,


233


. The sliding shoe in front of its tip


333


carries on a handle


33


with the fork


35


, a pair of deviating rollers


31


. The deviating rollers pair


31


is rotatably supported in the fork


35


through an axial


32


as shown in FIG.


3


. At the opposite side of the deviating roller pair


31


, the sanding belt


20


is guided over a driving roller


46


shown in

FIG. 3. A

housing axis


510


identified in a dot-dash line illustrates the longitudinal extension of the hand-held belt sander


10


.




A turning button


139


for adjusting a centering position of the sanding belt


20


is arranged in the front region of the longer housing shell


112


. It projects laterally and is integrated by arrangement in an indentation flush in the housing contour. During turning of the button


132


the fork


35


with the axial


32


and the handle


34


which carries the deviating rollers


31


is turned, depending on a rotary direction, in one or another direction.




Closely near the turning button


139


, the hand-held belt sander


10


carries a clamping and releasing lever


51


which projects laterally and is also integrated in the housing contour by arrangement in an indentation and flush with it. During turning of the clamping and releasing lever


51


about its axis


511


, the sanding belt


20


is released for exchange.




A suction hose


103


is connectable to the suction pipe


2101


. The suction hose is connected with an external, not shown dust aspirating device for aspiration of sanding dust.




An auxiliary handle


110


with its threaded piece


111


is screwable into a threaded opening


108


in the front region of the longer shell


112


of the housing


12


. Thereby the hand-held belt sander


10


can be adjustable in an especially fine and controllable manner.





FIG. 2

shows the hand-held belt sander


10


with a dismounted sanding belt


20


and the clamping lever


51


located in its releasing position in which it is turned downwardly. The deviating rollers


31


which are arranged in pair, the sliding shoe


33


together with the sanding bases


133


,


223


and the radially inwardly turned clamping roller


47


can be clearly seen from this Figure.





FIG. 3

shows a hand-held belt sander


10


in an explosion view. Its construction, its components and its operation can be easily recognizable. These figures specifically shows the housing


12


assembled of the longer and shorter shells


112


,


212


and forming a recess for


112


in the front region in view of their length difference.




A small pinion


215


which is not shown in detail supports a roller bearing and axially following impeller, and a partially shown roller of the motor


14


is connected to it. The small pinion


21


engages with the plate gear


115


of the transmission


15


, which is surrounded by a lubricant


1098


and is centrally fixably connected with a driven shaft


91


. The species


16


is held between the shelves


112


,


212


. The E-connecting cable


18


extending outwardly of the housing


12


is also held between the shells.




The sanding belt


20


can be seen at the left side in the observation direction, and the sanding basis


133


,


223


with the felt plates


43


arranged under them are located above the sanding belt. The deviating roller pair


31


with their axial


32


which carries at its ends pins


132


are shown above at the left side. Furthermore, the sliding shoe


33


with its tip


333


follows the handle


34


with the fork


35


at the right side. Its opening


44


merging into slot


533


and bore hose


331




332


can be easily seen in this Figure. The fork


34


in the mounted condition surrounds the sliding shoe


33


in a springy gap-free manner.




The handle


34


carries a bent tab


235


with an opening


135


for passage of an adjustment screw


39


. It is supported by spring


335


on the bottom of the opening


44


. The screw


39


is adjustable by an adjusting button


139


and operates for turning the handle


34


together with the deviating rollers


31


for centering of the belt running.




The design and the operation of the rear end


37


of the handle


34


is illustrated in FIG.


10


. This Figure also shows radii


38


,


41


in the groove button


40


of the slot


533


for guiding the fork


35


, which form a virtual rotary point


42


for the handle


44


.




The driving roller


46


shown in the upper, central region in

FIGS. 3 and 4

has small plates


146


which are separated from one another by inclined slots


246


. Belt clamping rollers


47


,


48


composed of synthetic plastic material are shown at the left side. By turning of the supporting lever


52


,


53


they are movable readily inwardly by means of the clamping and releasing lever


51


for exchanging the sanding belt


20


.





FIGS. 5-12

show the operation of the components illustrated in

FIGS. 3 and 4

. They include a plug


54


which projects on a lateral arm of the supporting lever


52


axis-parallel with it, a spring wire


55


, the transmission cover


57


, the torsion spring


59


, the pin


60


with the end


61


,


62


, a release


63


in the transmission cover


57


, a U-shaped clamping spring


64


with ears


65


,


66


, a reap


68


, an axial plug


69


, a longitudinal opening


70


, a flat spring


71


in the clamping-releasing lever


51


, its ends


72


,


75


, grooves


73


,


74


, an axial


76


of the clamping-releasing lever


51


, a slot


77


in the axial


76


of the clamping-releasing lever


51


, a longitudinal cortigation


78


in the flat spring


71


, transverse grooves


79


in the belt clamping rollers


47


,


48


, a pin


82


on the transmission cover


57


which forms the axis of the bearing lever


52


, a pin


182


which forms an axis for the bearing lever


53


, openings


282


,


382


in the bearing levers


53


,


52


, a circular-arc-shaped punch out


83


in the transmission cover, openings


85


a collar


86


, a needle bearing


87


for the driven shaft


91


, the release


88


, claws


89


forming an axial securing feature for the disk


22


of ceramic, a housing plug


90


, a profiled plug


93


of the adjusting plate


94


for the transmission gap adjustment, a plug


193


for floating the profiled plug


93


, a fixed bearing


95


, an arresting projection


96


, axial grooves


97


, a lubricant pen


98


, an outer wall


99


of the housing, a ring wedge


1


housing, a suction opening


1101


of the dust aspiration passage


101


, a suction pipe


2101


a threaded opening


102


in the sliding shoe


33


for an engagement of a holding screw of an underframe for mounting on the sliding shoe, both openings


1102


in the sliding shoe


33


for engaging of the plug of a not shown underframe for a stationary arrangement of the hand-held belt center


10


.




As can be seen from

FIGS. 5-8

, bearing levers


52


,


53


are provided for mounting the rollers


47


,


48


. The rollers can turn on the bearing levers over a circular path radially inwardly. The rollers


47


,


48


are turned inwardly as shown in

FIGS. 2

,


11


, for a belt exchange. In the operational position the roller


48


is mechanically arrested in its outer position, while the other roller


47


is pressed outwardly by a spring


59


. The fixedly arrested roller


48


abuts against a side of the sander, on which the sanding band


20


is inserted in the housing


12


. Thereby, independently on the belt length, a constant inlet gap


49


of less


6


mm between the running in belt


20


and the housing edge


50


is guaranteed for safety reasons. Thicker sanding bands lead however to smaller gaps. Both rollers


47


,


48


or bearing levers


52


,


53


are simultaneously actuated through a clamping/releasing lever


51


arranged outwardly on the housing


12


. For this purpose the bearing lever


52


which actuated directly through the clamping-releasing lever


51


is connected through an axial plug


54


on which a spring-wire piece


56


with an ear


56


is mounted as shown in

FIG. 4. A

sliding down of the wire


55


from the plug


54


is prevented since the free end of the plug


54


after mounting of the lever


52


ends directly over the upper surface of the bearing cover


57


. The other end of the wire


55


is mounted in the same way on the other bearing lever


53


. The engaging points


54


,


58


of the wire ends at both bearing levers


52


,


53


are selected so that during turning of the directly driven bearing lever


52


its plug


54


is moved outwardly forwardly and a pulling tensioning is produced in the connected spring wire


55


. This generates on the second bearing lever


53


a moment which turns the bearing lever


53


and thereby the second belt clamping roller


57


also inwardly. Since the directly driven bearing lever


52


in the clamping position assumes a defined position, while the other bearing lever


53


is deviated more or less due to the spring force independence on the belt length and thickness, the spring wire


55


between the lever


52


,


53


is angled so that a certain displacement between the engaging points is possible.




The bending angle and the wire length are selected so that despite the permissible displacement compensation, the driving operation of the spring wire


55


is not negatively affected. The application of the clamping force to the not directly actuated bearing lever


53


is performed through a torsion spring


59


. This spring is held on a pin


60


on the transmission cover


57


and its one end


61


is supported against a formation


63


in the transmission cover


57


and pressed by it simultaneously against the transmission cover


57


, so that the torsion spring


59


can not spring from the pin, while the other end


62


is supported on the axial


58


of the second clamping roller


47


and presses it thereby outwardly. Therefore, no additional components are needed for mounting of the spring


59


.




The blocking of the clamping mechanism in the clamping position is performed through a U-shaped clamping spring


64


with two ears


65


,


66


on its ends. One ear


66


surrounds the rotary axial of the directly actuated bearing lever


52


, while the other ear


65


surrounds the extension of the axial


67


of the directly actuated clamping roller


48


. The spring


64


is formed so that during the blocking process it slides with one corner on an inwardly projecting rib


68


of the housing


12


and therefore is deformed. At the end of the actuation path of the directly actuated bearing lever


52


, the spring can snap under the rib


68


and thereby to block the mechanism against a reverse turning. The unblocking of the mechanism is performed by the clamping/releasing lever


51


which has an axial plug


69


engaging in the U-shaped spring


64


. During the actuation of the releasing lever


51


, first the blocking spring


64


is pressed by the plug


69


laterally, before the bearing lever


52


is turned. In order to prevent a direct co-rotation of the bearing lever


52


so that the forces on the bearing lever


52


do not unblock the blocking spring


64


by the clamping/releasing lever


51


, the clamping/releasing lever is connected with a certain slack which is formed by an elongated hole


70


on the receptacle of the extension of the clamping roller axial


67


. Thereby the mechanism can be unblocked by hand only by actuation of the lever


51


.

FIG. 9

shows a front region of the hand held belt sander


10


from the side of the longer shell


112


. The turnable fork


35


of the handle


34


is supported at both sides on the concavely curved wall of the sliding shoe


33


which guides it as a supporting surface


39


. One of the two neighboring deviating rollers


31


can be seen in the drawing. An especial bearing for the deviating roller


31


is dispensed with, since they are composed of a special, high-grade synthetic plastic and run without lubrication on the axial


32


. The deviating rollers


31


can have a diameter of smaller than 8 mm. The pins


132


at the ends of the axial


32


engage in the openings of the fork


35


. For mounting of the axial


32


in the fork


35


, it is easily elastically bendable by an auxiliary tool manually. Subsequent, the axial


32


provided with the rollers


31


can be inserted. After this the fork


35


is compressed, the axial


32


is reliably clamped and is under slide pretensioning. The fork


35


acts simultaneously as a flat spring. Thereby the axial


32


and the rollers


31


can be exchanged with dismounting of the sliding shoe


33


or the hand held belt sander


10


.





FIGS. 17



a


and


17




b


show the auxiliary tool


36


for easy exchange of the deviating rollers


31


, for example in the case of wear. The tool


36


is an elongated, flat, synthetic plastic part which surrounds a side of the form


35


. It is supported in an immediate proximity outside on the sliding shoe


33


, runs with an engagement edge between the inner edge of the handle


35


and the end of the deviating roller


31


, and over a long lever


136


a convenient elastic bending of the form


35


with only hand is performed. Thereby, the roller


31


and the axial


32


can be easily withdrawn and exchanged.





FIG. 11

shows that for both-side axial support of the axial


32


, the handle


34


carries the fork


35


and is supported centrally with the opposite ends


37


in the sliding shoe


33


. For fixing of its lateral position relative to the sliding shoe


33


, the form


35


is curved inwardly concavely with the same curvature radius corresponding to that of the supporting surface


38


of the sliding shoe


33


. The design of the fork


35


as a pretensioned flat spring permits the construction of the abutment surfaces


38


of the sliding shoe


33


so that the fork


35


during turning relative to the supporting surface


38


must be slightly bent and thereby spring against the abutment surface


38


. Therefore, it sits without a gap in the sliding shoe


33


. The tilting of the total handle


34


for the belt running centering is performed by means of an adjusting screw


39


, manually with the rotary button


139


. It engages with the rear end


37


of the handle


34


and its axis is approximately parallel to the axis


32


of the deviating rollers


31


. The rear end


37


of the handle


34


is turnable by the adjusting screw


39


, and it is fixable in all degrees. During adjustment the end


37


of the handle


34


slightly slides against the rear support


40


which is formed in the groove bottom of the slot


533


. The radius


41


at the end


47


of the fork


35


is formed so that its central point is located in the virtual turning point


42


of the handle


34


, which is identical with the center points of the radii of the supporting surface


38


in the slide shoe


33


over the fork


35


. With another selection of the radius at the end


37


varying rotary points are provided during the adjustment.




For fixing the rotary point


42


no special axle is needed, in contrast to the known solution. Moreover, with the corresponding construction of the operational surfaces in the sliding shoe


33


, no special guiding parts are needed for the handle


34


.




The mounting of the handle


34


can be performed through the lateral opening


44


in the sliding shoe


33


. Since a mounting from the front is dispensed with, the central and the rear end of the handle


34


can be designed substantially freely, since they have yet to be introduced through a small opening at the front end of the sliding shoe


33


. This permits, for example, the angling of the plate, from which the handle


34


is produced to form a tab


235


with an opening


135


for passage of the adjusting screw


39


. By expanding the fork during the mounting around the greater radii


38


in the sliding shoe


33


, it is fixedly held in its position by the spring force. A tool for mounting or screwing or the like is not needed.





FIG. 11

shows how for producing the belt tensioning required for the operation of the hand-held belt center


10


, the sanding belt


20


is guided over the two rollers


47


,


48


, in addition to the deviating rollers


31


and the driving roller


46


. The rollers


47


,


48


operate only for providing the tensioned guidance of the sanding belt


20


.




As can be seen from

FIGS. 12

,


13


, the clamping/releasing lever


31


is composed of a synthetic plastic material. A multi-bent flat spring


31


is pressed in the synthetic plastic material and has two functions. One end


72


of the spring


71


which is formed as a projection and extends outwardly of the clamping/releasing lever engages in corresponding grooves


73


,


74


in the housing


12


, so that the lever


51


is arrestable in its both extreme positions. At the other end


75


, the spring


71


carries a V-shaft elongated cortilugation which, after fitting the lever


51


on its rotary axle


82


, engages in slot


77


of the axle


82


. Thereby the lever


51


is secured in an axial direction against displacement. Additional mounting means for fixing the lever


51


on the axial


76


are not necessary. Thereby, the lever


51


can be inserted with flush edge in the housing contour so that it can not be lost but at the same time it is mounted so that it can be easily releasable.




For mounting the spring


71


in the clamping/releasing lever


51


it carries a further elongated cartugation


78


. The elongated cartugation provides a press fit between the spring


71


and the lever


51


in the mounting groove. The belt clamping rollers


47


,


48


are composed of synthetic plastic material and run directly slidingly on the steel axles


58


,


67


.




In order to prevent deposits of wear particles, sanding dust, etc. on the outer surface of the rollers, the rollers


47


,


48


are not formed as smooth cylinders, but instead are provided with transverse groups


79


, similarly to a toothed belt sprocket. The dust and wear particles can laterally move out through the transverse grooves. The remaining supporting surfaces of the rollers are to the contrary so small that the dust and the wear particles can not deposit there.




This makes possible clamping of the grinding band


20


on the hand-held belt sander


10


by two movable clamping rollers


47


,


48


, which together are actuated by the single clamping/releasing lever


51


. The driving of the second varrying lever


53


is performed through the spring wire


55


while the pressing force of the second bearing lever


52


is provided through an additional torsion spring


59


. The mechanism is connected through the U-shaped blocking spring


71


which blocks it in a clamped position. This blocking is removed by the plug


69


in the clamping/releasing lever


51


during its actuation. For this purpose, a definite slack is provided between the clamping/releasing lever and the bearing lever


52


. A shaped flat spring


71


is pressed in the clamping lever and held through a cartigulation


78


in the clamping/releasing lever


51


. A further cartigulation


75


arrests in the slot


77


the axle


76


of the clamping/releasing lever


51


and thereby secures its axial position. The spring


71


is provided on its free end with a projection


72


. In the extreme positions of the clamping/releasing lever


51


it is arrested in the corresponding grooves


73


,


74


of the housing


12


and thereby arrests the lever


51


.




With the use of two clamping rollers


47


,


48


, instead of an adjustment of the deviating rollers


31


on the tip


333


of the sliding shoe


33


or the hand-held belt sander


10


, constant belt running conditions at the tip can be provided. The reason is that it always remains in the same position and thereby the belt


20


, independently from the belt tensioning runs always identically on the pressing surfaces


88


,


89


or bases


133


,


233


of the sliding shoe


33


.





FIGS. 5-8

and


10


show how the total support of the belt clamping mechanism for the hand-held belt sander


10


is provided by the transmission cover


57


. For this purpose two pins


77


,


82


are riveted on the transmission cover


57


which is formed as a punched member. They operate as axles for both bearing levers


52


,


53


. Furthermore, the transmission cover


57


is connected through circular-arc-shaped punched portions


83


,


84


operating for guiding and limiting the rotary movement of the bearing levers


52


,


53


. Also, it is mounted through a formation


63


under the clamping spring


59


of the clamping mechanism. Thereby the total clamping mechanism is premounted on the transmission cover


57


.




For fixing the transmission cover


57


in the housing


12


, it is provided with openings


85


, so that housing plugs


90


engage in them during the mounting. During the mounting the transmission cover


57


is clamped between the sliding shoe


33


and the housing


12


and fixed in connection with the known positioning plugs


90


. Therefore, no further mounting elements are needed.




The transmission cover


57


, in addition to the receipt of the clamping mechanism, also performs other functions. A collar


86


produced by punching receives the needle bearing


87


for the drive shaft


91


. The collar


86


serves simultaneously as a centering for a buffer disk of ceramic. It prevents a damage of the housing during a lateral running of the sanding belt


20


on the transmission cover


57


in the region of the driving roller


46


. A further formation


88


prevents a turning of the buffer disk


92


which is flatened radially at one side. This flatening engages exactly into the above mentioned formation


88


.




The axial securing of the buffer disk


92


performs during mounting by the sliding shoe


33


which for this purpose is provided with a special claw


89


which extends over the buffer disk


92


. The sliding shoe


93


is centered by the dome


90


in the housing


12


and supported through the transmission cover


57


on the housing


12


.




The cross-sections of the second example of the driving roller


36


shown in

FIGS. 14



a


-


14




b


have a specially defined peripheral region. With the use of a softer rubber mixture for the casing of the driving roller, a higher friction value is provided. With 2K tips a hard material is combined with soft strips to counteract the disadvantage that the rubber at high temperatures is soft, it deforms and wears out.




The driving roller


46


can sprinkled with a not shown grain material for example by glueing standard sanding agents. With this construction the friction value is also increased.




The arrangement of not shown wire brushes on a surface of the rollers composed of porous material also increases the friction value. Tearing-off of the brushes can be counteracted when the brushes are embedded in the material of the rollers so that only a short part extends outwardly the roller.




The casing of the driving roller


46


can be provided with inclined slots


246


to provide strip-like construction of the soft roller surface with strips


145


. Thereby an increase surface pressure under load onto the sanding belt


20


is obtained, since the strips which are inclined in the running direction of the sanding belt


20


is obtained, since the strips which are inclined in the running direction of the sanding belt


20


are arranged under the driving force of the belt. The roller diameter of the driving roller


46


is increased and the belt tensioning is increased as well, which leads to higher transmittable force to the sanding belt


20


. Furthermore, when the flattening is provided, a so-called polygon effect is achieved. The reason is that the sanding belt


20


with raised projection of the strips


146


no longer uniformly abuts against the whole surface of the roller, but instead runs only on the edges of the strips. As a result, a substantially higher surface pressure is provided.




In accordance with

FIGS. 15



a


,


15




b


,


15




c


, similarly to a free running drive, the driving roller


46


is knotched so that six arresting elements can be pressed in the knotches


2146


connected by an undercut and produced for example by extrusion. The arresting members can be formed of metal or synthetic plastic material which raise underload. This arresting members in contrast to projections, are not deformable, so that the desired affect of the pressing force increase is provided here in stronger way.




In accordance with a not shown embodiment of the invention, the roller can be provided with a coating composed of brushes. Similarly to the fleece, the ruffle up during stroking against the nap.




In accordance with a further not shown embodiment of the invention, an additional pressing roller is provided. It presses the belt radially outwardly against the driving roller


46


so that the transmittable force or the embracing angle can be increased. If the pressing roller is composed of a sufficiently soft material, practically no wear occurs, as long as it runs on the sanding side of the belt.




In accordance with still a further not shown embodiment of the invention, the sanding belt is perforated, substantially as in a small film. The perforations can be arranged on the belt not only at the edge, but also in the center or at any other place. Radially outwardly extending pins of the driving roller engage in the perforations so as to provide a form-locking connection and therefore an optimal force transmission.




Finally, in accordance with still another embodiment of the invention, a profiled is applied to the inner side of the belt. For example, transverse grooves corresponding to a toothed belt can be provided, while the driving roller has a corresponding counter profile, so that also a form-locking connection between the sanding belt and the driving roller is produced.




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.




While the invention has been illustrated and described as embodied in hand-held belt sander, 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.




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.



Claims
  • 1. A hand-held belt sander, comprising a housing; an on-off switch and a power supply conductor supported by said housing; a motor and a transmission received in said housing; a sanding belt; a driving roller driven by said motor and driving said sanding band; a sliding shoe provided with a base; a deviating roller arranged so that said sanding belt is guidable over said deviating roller and said base of said sliding shoe; means for centering said sanding band; means for clamping said sanding belt, said deviating roller and said driving roller have different diameters so that said sanding band is guided inclinedly, said housing being elongated and said sanding belt being guided on guiding parts which are introduced in a rear region of said elongated housing having a substantially uniform thickness, while in a front region of said elongated housing a centrally forwardly extending wedge-shaped contour is formed by upper and lower sides which converge starting from upper and lower sides of said rear region forwardly toward one another to a linear tip so that the hand-held belt sander as a whole has a lance-like contour with said elongated uniform-thickness rear region and said wedge-shaped tipped front region extending smoothly from both sides of said rear region.
  • 2. A hand-held belt sander as defined in claim 1, wherein said guiding parts are formed by said deviating roller and said sliding shoe.
  • 3. A hand-held belt sander as defined in claim 1, wherein said guiding parts have wedge surfaces which are symmetrical relative to a longitudinal axis of said housing.
  • 4. A hand-held belt sander as defined in claim 1, wherein said sanding belt has two edges, one of said edges projecting outwardly beyond said housing for edge-flush works.
  • 5. A hand-held belt sander as defined in claim 1, and further comprising a transmission cover; and two band tensioning rollers arranged near said driving roller substantially parallel to said driving roller and at a radial distance from the latter, said band tensioning rollers being supported on said transmission covers springy relative to said sanding belt.
  • 6. A hand-held belt sander as defined in claim 5, wherein said housing has a longer shell and a shorter shell; and further comprising a clamping and releasing lever turnably arranged on said longer shell and pullable into its outer contour, said housing directly above said clamping and releasing lever having an inclinedly arranged depression, so that when a finger is pressed on said clamping and releasing lever, it is guided inclinedly on a housing wall downwardly in a sliding fashion and therefore said clamping and releasing lever is easily actuatable.
  • 7. A hand-held belt sander as defined in claim 1, wherein said means for clamping said sanding belt include a handle with a fork which supports said deviating roller adjustable by an adjusting screw for belt running centering, said housing having a longer shell and a shorter shell; and further comprising a transmission cover, said sliding shoe forming one of said guiding parts and being formed as a one-piece wedge-shaped member and supporting said handle with said fork, said sliding shoe being mountable on said longer shell so that it presses said transmission cover against said longer shell in a region of connection of said shells.
  • 8. A hand-held belt sander as defined in claim 7, wherein said one-piece wedge-shaped member which forms said sliding shoe is composed of magnesium.
  • 9. A hand-held belt sander as defined in claim 7; and further comprising an adjusting button provided for said adjusting screw and arranged laterally on a front end of said longer shell near said clamping and releasing lever so as to extend outwardly and drawable into a contour of said longer shell.
  • 10. A hand-held belt sander as defined in claim 1; and further comprising a transmission cover, said housing being formed as a machine an angular transmission housing, said housing being composed of housing shells which are formed of synthetic plastic material and sealing reinforced by said transmission housing.
  • 11. A hand-held belt sander as defined in claim 7, and further comprising a further shoe which has a supporting surface for said fork, said supporting surface being concavely curved about a rotary point of said handle.
  • 12. A hand-held belt sander as defined in claim 7, wherein said handle is spring-elastically holdable in a neutral position; and further comprising an adjusting screw and a rotary knob actuating said adjusting screw for adjusting said handle.
  • 13. A hand-held belt sander, comprising a housing; an on-off switch and a power supply conduit supported by said housing; a motor and a transmission accommodated in said housing; a sanding belt; a drive rotatably driven by said motor and rotatably driving said sanding belt; a deviating roller; and a sliding shoe having a base and a working surface, said sanding belt being guided by said deviating roller and by said sliding shoe and pressed by said working surface against the workpiece; means for belt running centering; means for belt clamping, said housing having an elongated lance-shaped forwardly wedge contour, said driving and deviating rollers being arranged so that they are substantially coincide with a longitudinal axis of said housing, said housing having a rear region which is formed as a handle for two-hand operation.
  • 14. A hand-held belt sander as defined in claim 13, wherein said housing is composed of two shells which are joined together along a butt joint.
  • 15. A hand-held belt sander as defined in claim 14, wherein said shells are asymmetrical relative to one another both transversely and longitudinally, and said butt joint alternatingly extends outside and inside of said shells.
  • 16. A hand-held belt sander as defined in claim 14, wherein said shells include a longer shell and a shorter shell which amountable with one another so that in a front region of said housing a recess is formed, in which on said longer shell said deviating roller and said driving roller are arranged with said sanding belt.
  • 17. A hand-held belt sander as defined in claim 16, wherein said sanding belt having a fork-shaped end which engages with said shorter shell.
  • 18. A hand-held belt sander as defined in claim 16, wherein said driving roller engages with said shorter shell at a front end.
  • 19. A hand-held belt sander as defined in claim 13, and further comprising parts which guide said sanding belt and include said driving roller and said deviating roller, said guiding parts being arranged inside a contour of said housing in a wedge-shaped region of said housing, said deviating roller and said driving roller extending parallel to one another and transversely to an axis of said housing.
  • 20. A hand-held belt sander as defined in claim 16, and further comprising a transmission cover, said deviating roller and said clamping cover are being premountable on said transmission cover as an intermediate support, said transmission cover forming in a plane of separation of said housing a wall formed as a sheet metal cover so as to close inwardly said depression between said shells.
  • 21. A hand-held belt sander as defined in claim 13, wherein said housing is composed of a longer shell and a shorter shell, said longer shell having a contour which is formed as a wedge-shaped tip following a radially outwardly expanding region, said shorter shell having a contour substantially corresponding to said contour of said longer shell until an outwardly expanding region and is curved there in a U-shaped manner so as to be drawn rearwardly.
  • 22. A hand-held belt sander as defined in claim 21, wherein said outwardly expanding region of said shorter shell engages said sanding belt in a region of said driving roller to form a contact and dust protection, said shorter housing shell forwardly at an outer end of said outwardly expanding region at its one side being provided with an aspiration opening extending over a width of said shorter shell and communicating with a dust aspiration passage.
  • 23. A hand-held belt sander as defined in claim 22, wherein said shorter shell has a suction pipe at a rear region, said dust aspiration passage having a central region which is formed as a flat passage and extends in both said shells.
Priority Claims (1)
Number Date Country Kind
197 04 086 Feb 1997 DE
Parent Case Info

This application is a divisional of Ser. No. 09/013,351 filed Jan. 26, 1998, now U.S. Pat. No. 6,174,226.

US Referenced Citations (5)
Number Name Date Kind
2178865 Swan Nov 1939 A
3334447 Leveque Aug 1967 A
3427757 Redman Feb 1969 A
3619949 Welsch et al. Nov 1971 A
5210981 Urda May 1993 A
Non-Patent Literature Citations (1)
Entry
Model 55-L Dynafile Brochure, Dynabrade, Inc. 5-1977(copy in 451/355).