Electric heating – Metal heating – Cutting or disintegrating
Patent
1980-06-16
1983-03-08
Shaw, C. C.
Electric heating
Metal heating
Cutting or disintegrating
B23P 108
Patent
active
043762417
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an erosive cutting machine for the final machining of prepared closed inner shapes and closed outer shapes of a workpiece fixed by a workpiece holder by means of a filamentary or strip electrode arranged on guidance means.
BACKGROUND
Closed workpieces, e.g. punching or cutting tools have in many cases the feature that the contour to be cut with the electrode is not reachable from the outside, because the workpiece walls block access of the electrode and the guide means carrying the electrode. FIG. 1a shows such a cutting tool. The spatial dimensions are length 3 m, width 2 m and height 1.5 m. Such a cutting tool is used for cutting sheet metal parts such as e.g. automobile bodies after thay have been shaped. As is shown, after shaping, said sheet metal parts have material projecting beyond the shape limits. This material must be cut off by the cutting tool shown in FIG. 1a. The manufacture of such a cutting tool is very complicated, because the contour to be cut out represents a closed inner shape. An erosion machine can only cut this contour if the wire guide is particularly long. However, this means a considerable vibration of the electrode during the erosion process. Thus, the requisite precision would not be maintained. The cutting tool can obviously have smaller spatial dimensions than those of FIG. 1a. In the case of a smaller tool, an erosive cutting machine could not cut the closed inner shape, even with lengthened wheel guidance means. FIG. 1b shows a punch having a closed outer shape and can either be a blanking punch or a cutting punch. The external dimensions of the punch can be up to a few meters. The closed outer shape of the punch cannot be machined in one operation with the known working methods, because it is fixed in a clamping system and the working machine, e.g. the erosive cutting machine, would collide with the clamping system. To avoid such a collision, the closed outer shape can only be machined in parts. The punch must then be reclamped in the clamping system and the new alignment then takes place between punch and erosive electrode. As a result of these difficulties, manufacture of such cutting and punching tools has taken a considerable time and is very complicated, which leads to high costs.
THE INVENTION
The problem of the invention is to obviate these difficulties or disadvantages occurring in the manufacture of special tools. The invention also aims at transferring the advantages of erosive machining by means of a filamentary or strip electrode to the present specifically shaped workpieces. The invention also aims at attaining the aformentioned advantages by means of a simple constructional solution, so that one of the constructional embodiments according to the invention can be installed on existing erosion machines.
According to the invention this problem is solved in that for avoiding a collision between the guidance means and the closed inner shape or the closed outer shape and the workpiece holder at least one guidance means is provided on the motor-rotatable rotating mechanism, whose centre line coincides at at least one geometrical locus with the centre of the cross-section of the electrode.
Important features of the constructions according to the invention can be gathered from the claims.
DRAWINGS:
The figures show FIG. 1a and 1b are punch elements to be made by the machine apparatus;
FIG. 2 an embodiment of the invention where, as desired, one or two guidance means for the electrode are provided on a rotating mechanism.
FIG. 3a the cutting of a workpiece with closed outer shape.
FIG. 3b the cutting of a workpiece with a closed inner shape.
FIG. 4 a further embodiment of the invention with sensors on the guidance means.
FIG. 5 an elecrode arrangement according to the invention to and from the guidance means in a sectional view along the section line A--A of FIG. 2.
FIG. 6 a part sectional representation of an electrode supply and discharge arrangement according to the invention.
FIG. 2 is a part sectional representation of the machini
REFERENCES:
patent: 3731044 (1973-05-01), Ullmann et al.
patent: 4123645 (1978-10-01), Shichida et al.
patent: 4307279 (1981-12-01), Inoue et al.
A.G. fur Industrielle Elektronik AGIE
Shaw C. C.
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