Turning – Lathe – Multiple
Reexamination Certificate
2000-03-20
2001-10-09
Tsai, Henry (Department: 3722)
Turning
Lathe
Multiple
C082S122000, C082S124000
Reexamination Certificate
active
06298759
ABSTRACT:
The present invention relates to the subject matter disclosed in German Patent Application No. 199 16 212.3 filed Apr. 10, 1999, the entire specification of which is incorporated herein by reference.
The invention relates to a multi-spindle machine-tool, in particular a multi-spindle automatic lathe, with multiple workpiece spindle units which are arranged around a central axis for rotational drive and advance from one machining position to the next.
BACKGROUND OF THE INVENTION
Multi-spindle machine-tools with multiple workpiece spindle units are, for example, known from EP 0 726 119 A1 or DE 196 19 720 A1. These known machine tools have a spindle drum, mounted on a machine frame, on which the workpiece spindles are mounted at rigidly fixed equal angles to one another and with which they are brought into the various machining positions by advancing the spindle drum. When the spindle drum is arrested in order to fix the workpiece spindles in their respective machining positions, machining of the workpieces clamped into the workpiece spindles takes place at the machining points, after which the spindle drum is advanced again and the workpiece spindles with the workpieces reach their next machining position.
It is a known practice, from DE 196 19 720 A1, to provide the individual machining stations with tool slides with two tools and to advance the spindle drum in such a way that, within each machining station, each spindle can be positioned successively in two positions so that the workpieces clamped in them are first machined by the first tool—in the direction of travel of the spindle drum—and are then, after advancing by a small angle, machined by the second tool. In this machine, twice as many machining positions as workpiece spindles are provided, if one looks down from the loading and unloading stations for loading and unloading of the workpieces.
The regular disposition of the workpiece spindles on the spindle drum in the known multi-spindle machine-tools has the disadvantage that the spindle drum can only be advanced when the longest-lasting machining process at one machining station has been completed. The stroke-time, that is the time until the drum is advanced, along with all workpiece spindles, is thus determined by the longest lasting machining operation at one machining station. It is thus often the case that only one tool at its respective station is engaged upon the workpiece, while at all other machining stations processing is already complete and the machining capacity of the individual machining stations cannot be exploited fully because of the enforced dead time. A further disadvantage of the advanceable spindle drum is that, for it to be moved in this circular advance process, its mass should ideally be as small as possible in order to achieve the required high speed of movement to advance the workpiece spindles into the next machining position. In order to keep the mass of the spindle drum within reasonable limits, its diameter and thus also that of the spindle circle must be kept as small as possible, which restricts the room available for the workpiece spindle units and which also leaves little room for arrangement of the machining tools in the individual machining stations and for the loading device. Reducing the spindle drum to the smallest possible size means that the central spindle-carrier too, on which the spindle drum, especially in the case of vertical machines, is normally mounted, cannot be designed as large as one would like so that it often lacks the required rigidity. A further disadvantage of the known machines is that the tool-carriers are arranged in fixed positions and thus cannot always be positioned optimally with respect to the workpiece.
SUMMARY OF THE INVENTION
The object of the invention is to create a multi-spindle machine-tool of the type set out above which produces the greatest possible flexibility in machining in the individual machining positions and with which the time available for machining in the machining positions can be exploited to the full by the workpiece spindle units.
This object is achieved in the invention in that the workpiece spindle units are moveable independently of one another along a movement path running around the central axis and that the machining positions are distributed and are designed as machining segments, within whose limits the respective workpiece spindles or workpiece spindle units are moveable during a machining process along the movement path.
The invention thus departs from the beaten path of the state of the art, in which adjacent workpiece spindle units, because of their arrangement on the spindle drum, are always at a fixed distance from one another. On the contrary, according to the invention the workpiece spindle units are moveable along the movement path independently of one another and thus their positions relative to one another can be altered. It is thus also possible to vary the size of the machining segments in certain areas and for example to provide two machining stations—arranged one after the other in the direction of the movement path—in one machining segment while in another, for example the immediately adjacent, machining segment, only one machining station is located and this machining segment is thus kept correspondingly smaller. With the arrangement according to the invention it is thus possible to have a machining process, which requires a long period of time, being carried out in an appropriately small machining segment with just one machining station, while in other machining segments within (approximately) the same processing time several machining processes are carried out at two or even more machining stations, for which purpose the relevant workpiece spindle unit can be moved within its machining segment along the movement path.
In addition, the arrangement according to the invention has the special advantage that owing to the movability of the workpiece spindle units along the movement path within the machining segment the spindle itself executes the required movements for processing of a workpiece in the direction of the X axis, which in the machine-tool according to the invention coincides with the movement path or runs parallel to the latter. Unlike the multi-spindle machine-tools known from the state of the art, the workpiece spindle units in the invention do not actually have to be arrested in a fixed position in the orientation of the X axis, but can move forward or backward within the limits of the machining segments. The required relative mobility between tool and workpiece in the orientation of the X axis need not therefore be realized by a tool—or workpiece slide—which is moveable in the direction of the workpiece spindle, but instead the tool—or the workpiece—can be positioned at a fixed point at the machining station within the machining segment, making an especially stable arrangement possible.
Normally it will be appropriate for the workpiece spindle units to be moveable along a circular movement path which runs around the central axis; however, it is also perfectly possible for the movement path to have another shape if this seems appropriate for the machining processes to be carried out. For example, the movement path can be elliptical, or may consist of two parallel straight line sections which at their ends are connected by bow or semi-circular sections (a longitudinal hole shape). The concept “central axis” should therefore not be understood within the meaning of the invention to mean that all workpiece spindle units are always at the same distance from the axis, rather “central axis” should be taken to mean an axis which is arranged in the interior of the closed movement path around which the workpiece spindle units travel and which forms the center of the movement path. In a preferred design of the invention where the invention is designed as a vertical machine-tool, and the axis is a vertical axis.
It is especially useful if each workpiece spindle has its own rotary drive so that each workpiece spindle can be rotated fully, independently o
Herrscher Albert
Langer Detlef
Alfred Schutte GmbH & Co.
Tsai Henry
Vickers Daniels & Young
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