Metal working – Plural diverse manufacturing apparatus including means for... – With turret mechanism
Reexamination Certificate
1999-12-16
2001-10-09
Briggs, William (Department: 3722)
Metal working
Plural diverse manufacturing apparatus including means for...
With turret mechanism
C029S036000, C029S039000, C082S129000
Reexamination Certificate
active
06298531
ABSTRACT:
FILED OF THE INVENTION
The invention relates to a machine tool, in particular for metal-cutting machining of workpieces.
BACKGROUND OF THE INVENTION
For machining workpieces of complex shape, which for their production must pass through a relatively large number of different metal-cutting machining processes, especially for mass-scale machining or production of such workpieces, machine tools are often used that on the same workpiece successively perform different machining operations from different directions. One example of such a machine tool can be found in U.S. Pat. No. 5,452,502. The machine tool disclosed there is embodied as a circular indexing machine tool and has a cross-shaped workpiece carrier disposed inside a cage-like base frame. Workpiece receptacle devices are disposed on the side faces of the arms of the cross-shaped workpiece carrier. While the workpiece carrier can be rotated and indexed about a vertical axis, the individual workpiece receptacles are each rotatable about horizontal axes, which are disposed at a tangent to an imaginary circle. As the workpiece carriers index onward, the workpieces successively pass through different work stations. These stations are defined by machining units, which are retained on the basic frame so as to be adjustable in multiple directions. Each machining unit has one work spindle, which is provided with a revolver head. The revolver head is embodied as a crown type turret head. Its spindles are driven jointly by the work spindle. By revolution of the revolver head, a desired tool can be transferred into a rectilinear lengthening position of the work spindle, thus putting it in the machining position. All the spindles of the revolver head are driven simultaneously, and they continue to move even during the rotation or onward indexing of the revolver head.
With this circular increment machine tool, five-sided machining of the workpieces is possible, which makes for high efficiency. However, oblique faces or oblique bores, that is, bores that do not form a right angle with the axis of rotation (horizontal axis) of the workpiece, present a certain problem in machining. In special cases, in which because of the workpiece design different machining times are needed in the various work stations, it is also possible that the machining units of different work stations may work for variously long times. The indexing time is determined by the longest machining time required.
SUMMARY OF THE INVENTION
With this as the point of departure, it is the object of the invention to provide a remedy for this and to create a machine tool with which the most uninterrupted possible operation of individual work spindles and thus a high degree of utilization are attainable even if individual sides of the workpieces have to be machined for variously long times.
This object is attained according to one aspect of the invention that makes it. In its simplest structural form, the machine tool has a machining unit that serves two workpiece receptacles. Each workpiece receptacle is embodied such that it can pivot the workpiece into at least a mounting or removal position and into at least one defined position but preferably a plurality of selectively definable work positions. The pivot axis preferably passes crosswise through the workpiece and in the ideal case through its center. Preferably, the pivot axis does not touch or intersect the workpiece fastening face but instead extends parallel to it and spaced apart from it.
Both workpiece receptacles are disposed in the immediate vicinity of one another, and the machining unit can be moved by means of the guiding and adjusting device in such a way that it machines either one or other workpiece. Since the time required for changing workpieces is as a rule substantially shorter than the machining time, it is thus possible to keep the workpiece in action practically constantly. Inactive times, as otherwise can occur if it is necessary to wait for other work spindles or in a change of workpieces, can be averted.
While the work spindle is adjustable in the lateral direction along its travel, the length of which spans both workpiece receptacles, it is adjustable in an additional direction perpendicular to the lateral direction and to its axis of rotation. It is also adjustable in the direction of its axis of rotation, to enable a positioning motion. These three axes enable flexible machining of the workpieces.
All the NC axes (the X, Y, and Z axes, as well as the pivot axis S and adjusting axis V) serve the purpose of positioning in machining a workpiece. Thus the workpiece is transported from the loading position to the work position at the same time, so that no additional transport axis or motions are required. If needed, however, an additional transport axis may be provided.
In an advantageous embodiment, at least two machining units are provided, whose work spindles are for instance at a right angle from one another. Both machining units are adjustable in the lateral direction far enough that they can machine both workpieces in alternation. The machining units can either both work on the same workpiece or on different workpieces. In conjunction with the possible pivoting of the workpieces about the pivot axis, this enables a compensation of the possibly variably long machining times for different sides. For instance, if machining the end face of the workpiece, which is opposite its fastening face, is especially labor-intensive, then both the machining units can be used for that. While the first machining unit can machine the first workpiece on its face end, the second machining unit, which is oriented differently, can machine the correspondingly pivoted other workpiece on its face end. If the machining of side faces is less labor-intensive, then this machining can for instance be performed by a single machining unit, which to that end is moved suitably laterally to one or the other workpiece.
The advantages of the novel machine tool become especially apparent if the work spindles are provided with revolver heads or crown type turret heads. If the spindles present in these revolver heads and each carrying one tool are driven from the central work spindle, and if the onward indexing of the crown type turret heads takes place while the spindles are moving, then extremely short changing times, which are less than one second long, are achieved. Work can thus be done practically uninterruptedly. The high flexibility that the machine tool of the invention offers in terms of dividing up the individual operations among individual machining units and tools, makes it possible here for the existing work spindles to be utilized equally, so that the idle times of the machine can be kept quite low.
In a preferred embodiment, the two workpiece receptacles are disposed adjacent one another and side by side, and the pivot axis is oriented horizontally. This has the advantage that the workpieces can each be changed at the same height, and that a relatively flat machine frame can be used, which can easily be designed to be rigid. This is favorable for the machining precision.
The two machining units are preferably oriented in different directions in space. For example, the first work spindle is disposed horizontally and the second work spindle is disposed vertically. This makes it possible for both machining units to work on the same workpiece at once. The machine tool can as a result be programmed quite flexibly, and it is even possible for workpieces that require quite different machining times on different sides to be machined without stopping or idly running individual work spindles. Furthermore, the work spindles can be moved past one another without colliding with one another (for instance, the first work spindle can be moved from the first to the second workpiece and the second work spindle can be moved from the second to the first workpiece).
A height adjustment of the workpiece with respect to its workpiece receptacle, or in other words an intended adjustment of the spacing between the center of the workpiece and the
Bauer Walter
Baumbusch Frank
Briggs William
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Witzig & Frank GmbH
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