Router

A router includes a motor housing, from the underside of which a tool fitting for a milling tool connected with a drive extends, and which includes a guide unit—with at least two guide columns—for the motor housing, which is displaceably accommodated on the first guide column in at least one bearing, and on the second guide column in at least a second bearing. The at least one bearing is designed at least partially as a rolling element guide.

CROSS-REFERENCE TO A RELATED APPLICATION

The invention described and claimed hereinbelow is also described in German Patent Application DE 102006061235.3 filed on Dec. 22, 2006. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The present invention is directed to a router.

A generic router is made known in DE 41 39 759 A1. The router includes a motor housing, from the underside of which a tool fitting for a milling tool extends. The motor housing is connected with a base plate via two guide columns. The router includes a rod that cooperates with a rotary plate to roughly adjust the milling depth. To make fine adjustments of the milling depth, the motor housing may also be raised or lowered by small amounts relative to a guide column. This milling depth adjustment of the router is supported in a sliding manner.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a router which is a further improvement of the existing routers.'

In keeping with these objects, the present invention in particular relates to a router which includes a motor housing, from the underside of which a tool fitting for a milling tool connected with a drive extends, and which includes a guide unit—with at least two guide columns—for the motor housing, which is displaceably accommodated on the first guide column in at least a first bearing, and on the second guide column in at least a second bearing.

It is provided in accordance with the present invention that at least one bearing is designed at least partially as a rolling element guide.

A design of this type makes it possible to adjust the milling depth of a router easily and precisely, since a rolling element guide also moves easily in the absence of play, i.e., with preload. With the rolling element guide, the motor housing and, therefore, the milling tool may be supported in a low-friction and jerkless manner, even without bearing play, thereby enabling the router to be adjusted quickly and accurately to a reference surface. Advantageously, the low-vibration guide of the milling tool results in greater dimensional stability and surface quality of the work piece to be machined, and it results in increased user-friendliness of the router, since its set-up time is thereby reduced.

In a further embodiment it is provided that the second bearing includes a rolling element guide and a sliding guide, thereby resulting in an advantageous stiffening of the motor housing via a non-rotatable positioning of the motor housing relative to the base plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows an inventive router, in a partially exposed view. The router includes a two-piece motor housing, which is composed of an upper piece1—preferably made of plastic—and a lower piece2, which is preferably made of aluminum.

A drive motor3, which starts a motor spindle4rotating, is located in motor housing1,2. Motor spindle4is non-rotatably connected with a tool fitting, preferably in the form of a clamping sleeve5—which may be clamped using a hexagon nut6—in which a milling tool may be clamped, in order to machine a work piece.

Two handles7,8are installed on upper piece1, and they are preferably integrally moulded with upper piece1. An electrical switch9for starting the router is provided in one of the two handles8. Switch9is connected via electric lines10,11with drive motor3and a power connection cord12.

First guide tubes14a, b, which extend essentially parallel to a vertical axis13of the router and a vertical axis13of the milling tool, are integrally moulded with the lower piece of the motor housing. First guide tubes14a, bline up directly with second guide tubes16a, b, which are also oriented essentially parallel to a vertical axis13of the router and a vertical axis13of the milling tool, and which are integrally moulded with base plate15.

Two guide columns17,18of a guide unit38are guided and supported in first and second guide tubes14a, band16a, b. A first guide column17, as the main column, is hollow in design, and a second guide column18is solid in design. Motor housing1,2is accommodated—such that it is displaceable essentially parallel to axis13of milling tool—on first guide column17in at least a first bearing19, and on second guide column18in at least a second bearing20, and it is detachably fixable in position relative to at least one of the guide columns17,18using a clamping device21,22. A snap ring23is located in an annular groove on an upper end of solid guide column18facing upper piece1; it prevents motor housing1,2from accidentally sliding off of guide columns17,18. Solid guide column18prevents motor housing1,2from rotating, and serves to limit the upper extent of the reciprocating motion.

Base plate15includes a lower piece24—which is preferably composed of plastic—for protecting the work piece to be machined. Base plate15and lower piece24have a central opening25, into which motor spindle4of drive motor3located in motor housing1,2extends at least partially. According toFIG. 2, a rotary plate27with three adjustable screws28is installed on base plate15, as a stop for a rod26, for adjusting the milling depth. Rod26is fixed in position via a fixing screw29, which has been inserted in a screw thread in lower piece2of the motor housing. To adjust the desired milling depth more easily, a scale30is provided on housing upper piece1, and a displaceable sliding element31made of Plexiglas with a marking line is mounted on rod26.

Motor housing1,2is capable of being fixed in position relative to base plate15via the clamping device—in the form of a clamping sleeve21—which is displaceably guided on main column17, using a clamping screw22. Clamping screw22is seated in a thread of clamping sleeve21—which extends nearly at a right angle to the axis of main column17—such that it is capable of being pressed against clamping sleeve21. Clamping sleeve21includes an outer thread32on its outer circumference, onto inner thread33of which a stepped adjusting element34—which is hollow-cylindrical in the lower section and which is preferably made of plastic—is screwed. Inner thread33has preload relative to outer thread32, to eliminate thread play. This may be brought about, e.g., by using a slightly larger or smaller thread pitch, or by using a slightly overlapping thread profile.

The upper part of adjusting element34is designed as a full cylinder and forms a central neck35. Housing upper piece1is located on shoulder36formed on the transition from the hollow-cylindrical piece to neck35. An axial antifriction bearing37is inserted between shoulder36and housing piece1. Housing piece1is fixed in position relative to adjusting element34such that it may be adjusted without play using a not-shown nut screwed onto neck35or using any other type of fastening means.

A rotary knob39with an external knurl is screwed onto neck35. A scale ring40, which may be adjusted to zero relative to rotary knob39, and which is subdivided into tenths of millimeters and/or 1/256ths of an inch, is inserted between rotary knob39and housing upper piece1.

A long spring41is located inside main column17. Long spring41is supported on base plate15and against adjusting element34. Spring41, which is designed as a compression spring, ensures that motor housing1,2is lifted relative to base plate15when clamping screw22is open, so that a milling tool inserted in motor spindle4emerges from the work piece. Compression spring41is supported against adjusting element34, with a disk42having a central projection43inserted between them. In the exemplary embodiment shown, projection43is designed as a ball inserted in disk42. It rests in the center of the base of adjusting element34. To this end, adjusting element34—which is otherwise preferably made of plastic—may be reinforced with, e.g., an intermediate metal ply. A mandrel44extends downward and away from disk42and into compression spring41; it prevents compression spring41from collapsing.

The milling depth of the router is adjusted as usual, using rod26and rotary plate27, as shown inFIG. 2. In practical application, it often becomes apparent that the milling depth was adjusted too low or too flat by a small amount, e.g., fractions of millimeters. Since it is not possible to make such a small correction via the rough adjusting using rod26, a device for making fine adjustments is also provided. The correction required may be brought about by using the device or by making fine adjustments with the milling tool inserted in the work piece, without changing the rough setting of the milling depth.

When rotary knob39is rotated, the milling depth is changed by the amount indicated in tenths of millimeters on scale ring40. The resultant rotation of adjusting element34relative to clamping sleeve21fixedly connected with main column17and, therefore, base plate15, results in motor housing1and2—which is displaceably accommodated on guide columns17,18in two bearings19,20—being raised or lowered slightly, depending on the direction of rotation of rotary knob39.

According to the present invention, at least one bearing19,20is designed at least partially as a rolling element guide. The rolling elements may be balls, rollers, or other rolling elements. The rolling element guide may be a linear guide, a circulation guide, or a guide without circulation. A circulation guide includes rolling elements, which circulate in an endless rolling element circulation. In the present exemplary embodiment, first bearing19on solid main column17includes two rolling element guides45located one on top of the other, although a long rolling element guide would be feasible as an alternative. Second bearing20on solid guide column18includes a rolling element guide46and a sliding guide47. Other alternatives are also feasible, however.

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 type described above.

While the invention has been illustrated and described as embodied in a router, 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.