Apparatus for machining an elongated workpiece

An apparatus for machining an elongated workpiece with a tool a support column having a generally planar and vertical front wall and a pair of generally planar, parallel, and vertical side walls projecting rearward from respective outer edges of the front wall. A workpiece holder on the front wall can hold the workpiece forward of the front wall in a vertical orientation. A vertical guide secured to one of the side walls carries a vertical slide shiftable along the vertical guide. A front horizontal guide on the vertical slide forward of the front wall from the guide carries tool holder shiftable in the front horizontal guide on the vertical slide forward of the front wall and is adapted to hold the tool.

FIELD OF THE INVENTION

The present invention relates to a machining apparatus. More particularly this invention concerns an apparatus for grinding, milling, boring, lathing, or otherwise machining an elongated workpiece.

BACKGROUND OF THE INVENTION

A standard apparatus for machining an elongated workpiece with a tool is described in German patent document 10 2008 037145. It has a support column having a generally planar and vertical front wall on which is mounted a workpiece holder for holding the workpiece forward of the front wall in a vertical orientation. A pair of vertical guides on the front is walls flank the workpiece holder and each carry a vertically shiftable vertical slide forward of the front wall. Each vertical slide in turn has a horizontal guide on which is mounted a respective tool holder horizontally shiftable in the respective horizontal guide on the vertical slide forward of the front wall and adapted to hold a respective tool. Thus horizontal movement of the holders on the respective vertical slides engages the tools horizontally with the workpiece in the workpiece holder and vertical movement of the vertical slides in the respective guide moves the tools vertically along the tool.

The problem with this construction is that it is quite wide. The guides and workpiece holder must move vertically in their own paths so that the apparatus has to be wide enough measured horizontally parallel to the front wall to accommodate all this equipment. This is disadvantageous in an operation where a number of such apparatuses need to be accommodated and, often, served by a single person or automatic loader/unloader.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved machining apparatus for elongated workpieces.

Another object is the provision of such an improved machining apparatus for elongated workpieces that overcomes the above-given disadvantages, in particular that is of reduced width.

SUMMARY OF THE INVENTION

An apparatus for machining an elongated workpiece with a tool a support column having a generally planar and vertical front wall and a pair of generally planar, parallel, and vertical side walls projecting rearward from respective outer edges of the front wall. A workpiece holder on the front wall can hold the workpiece forward of the front wall in a vertical orientation. A vertical guide secured to one of the side walls carries a vertical slide shiftable along the vertical guide. A front horizontal guide on the vertical slide forward of the front wall from the guide carries tool holder shiftable in the front horizontal guide on the vertical slide forward of the front wall and is adapted to hold the tool. Thus horizontal movement of the holder on the vertical slide engages the tool horizontally with the workpiece in the workpiece holder and vertical movement of the vertical slide in the guide moves the tool vertically along the workpiece.

DETAILED DESCRIPTION

As seen inFIG. 1a machining apparatus according to the invention has a machine frame formed by a column1of square cross-section and having vertical and planar side walls2and2′ and a similarly vertical and planar front wall3extending between front edges of the side walls2and2′. The front wall3defines a plane E (FIG. 3d), and the side walls2define parallel planes F perpendicular thereto. The side wall2carries a pair of vertical guide rails5on which a vertical slide4can shift vertically parallel to a vertical axis Z. An actuator6carried at the top of the wall2engages via an unillustrated ball screw with the vertical slide4to shift it up and down. The vertical slide4in turn is provided with a pair of vertically spaced and horizontally extending guide rails16on which a horizontal slide15can travel under the control of an unillustrated drive like the actuator6. This slide15in turn carries a tool holder10that is pivotal on the slide15about a horizontal axis17perpendicular to the plane E. The holder10holds tools14and14′ and a grab11.

A workpiece holder8is provided on the front wall3and comprises a driven headstock9and a coaxial tailstock22. The headstock9can be moved along vertical guide rails19on the front wall3above the tailstock22. An actuator6′ like the actuator6can vertically displace the headstock9. During machining the workpiece7is rotated about a vertical axis A.

A conveyor26transports unmachined workpieces7to a loading/unloading station20and moves machined workpieces7away from it. For loading, the grab11removes a workpiece7from the station20and fit it to the headstock9and tailstock22. For unloading the grab11takes the finished workpiece7and places it in the station20, with appropriate movement of the slide15in its guide16and of the holder10about its axis17.

The machining apparatus ofFIG. 2serves for end machining. Here the workpiece7is clamped centrally in a vise29fixed on the front wall3forward of the plane E so that it is vertically fixed and nonrotatable. On the right-hand side wall2′ of the machine, a second guide5′, vertical slide4′, slide15′, and tool holder10′ are provided, symmetrically to the first guide5, vertical slide4, guide16, etc. This assembly can also is move parallel to the vertical axis Z and horizontally parallel to the axis X. The symmetrical arrangement of the two tool assemblies allows workpieces7to be machined simultaneously on both ends. While the workpiece7is securely clamped in the vise29the tools14are rotated.

InFIG. 3the system is identical to that ofFIG. 2except that instead of the vise29the front wall3carries an upper vertically shiftable headstock9like inFIG. 1and an also driven lower headstock18axially aligned with the upper headstock9. This way the workpiece7can have its sides machined along its full length as inFIG. 1, and by moving it axially back and forth between the chucks of the headstocks9and18it is also possible to machine both ends of the workpiece7, for instance drilling a hole in the end. A tailstock center28is advantageously provided on the workpiece holder10. This enables the workpiece7to be supported whenever machining does not allow clamping in the lower headstock18.

To machine the lower end of the workpiece7, it is first clamped in the headstock9and this lower end is machined by the tool14as shown inFIG. 3a. The headstock9then travels downward (FIG. 3b) and transfers the workpiece7to the chuck of the lower headstock18and then returns to its original upper position, whereupon the workpiece holder10moves horizontally and pivots about its axis17until its tool14is concentric to the lower headstock18. The upper end of the workpiece7projecting up from the lower headstock18can then be machined (FIG. 3c).

FIG. 3dshows how vertical slides4and4′ movable vertically along the side-wall guides5and5′ can carry is respective horizontal guide rails32and32′ on which respective intermediate slides33and33′ can shift horizontally forward and back parallel to the horizontal axis Y and perpendicular to the plane E. In turn the front horizontal guides16and16are fixed on the vertically and horizontally movable slides33and33′ and carry the tool slides15and15′. Here also tool holders23and23′ are pivotal about vertical axes17on the slides15and15′ and carry the various machining, drilling, and grinding tools14. The holder23also carries, in addition to the grab11and tools14, a steady rest21for holding the workpiece7on center during machining, if necessary. This arrangement allows the distance between tool engagement of the workpiece and machine frame to be significantly shortened. As a result, the flow of force is improved and the rigidity of the machine is significantly enhanced.

In the grinding machine ofFIGS. 4 and 5, two vertical slides4and4′, and horizontal slides15and15′ are able to move vertically via shoes27(FIG. 5) on the guides5and5′ along the side walls2and2′ of the column1, as is the case with the apparatus for end machining ofFIG. 3. A grinding spindle head24with grinding wheel25carried on the slide15′ can be shifted horizontally toward the workpiece7on the horizontal guide16. A multifunction unit23is associated with grinding spindle head24on the opposite side of workpiece7. This unit23is rotatably supported on the horizontal slide15about a vertical pivot axis17.

Various modules on the multifunction unit23include the self-centering steady rest21and two sensors12that support and effect in-process measurement of the workpiece7. The sensors12are concentric relative to the steady rest21, thereby enabling the workpiece diameter to be gauged during grinding and support to be simultaneously provided by the steady rest21. In addition, the grinding wheel25can be dressed by a unit13carried on the slide15. Loading and unloading is effected with the grab11, as inFIG. 1.

The arrangement of vertical slides4and4′ on both walls2and2′, and of the workpiece holder on the front wall3of the column1produces an especially rigid construction for the machine. The grinding machine is nevertheless extremely compact and takes up only a small footprint. In addition, the machine can be flexibly employed because the multifunction unit23together with different tools14and the steady rest21enable complex machining procedures to be performed. A total of only four controlled linear axes is required since the grab11, the sensor12, and the dressing unit13are all mounted on the multifunction unit23that is movable in two axes. For loading and unloading, the grab11removes workpieces7from the station20and feeds them to the headstock9. As this occurs, the horizontal slide travels along the guide rails16, while the tool holder10pivots about the pivot axis17.

FIG. 6shows a four-axis grinding machine for synchronous grinding. Here two grinders24and24′ are disposed in mirror-inverted fashion, and can move in the X axis and Z axis on the respective vertical slides4and4′ and horizontal slides15and,15′. This arrangement enables, for example, a main bearing30of a crankshaft to be ground. Similarly, the crank pins31of a center-clamped crankshaft can be machined using the pendulum-stroke method.