Title: Punching press with tool exchanging means

Description: BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to a punching press including exchangeable tool sets having upper and lower punching tools wherein the parts punched out by the punching dies of the tools are discharged through a stacking duct in the lower punching tool. The punching press of the present invention may advantageously be utilized for punching out sheet-metal parts for electrical machinery and the like.

A substantial disadvantage of previously contemplated punching presses of this type is that an exchanging of the punching tools (blanking dies) is very cumbersome and time-consuming due to the fact that basket- or cage-type stacking ducts through which the cut-out metal sheets were discharged from the area underneath the punching tool were extended through an underlying press table or workholding plate and were attached in the zone of the underside of the tool. Consequently these stacking ducts had to be detached and lowered before each exchange of punching tools or dies. Prior arrangements also required removal of a portion of the metal sheets present in the ducts from the tool zone before the tool could be removed or disassembled.

The present invention contemplates providing punching apparatus which avoids the above-mentioned disadvantages by configuring and constructing the stacking ducts so that they need not be detached and removed or emptied during exchange of punching tool sets.

An important feature of the present invention is the spacing of the stacking duct structure from a conveying system for removal of the punched out parts from the stacking ducts and the spacing of the stacking duct structure from the press table surface of the press which supports a toolholding plate and the lower punching tool. In a preferred embodiment of the invention, the conveying system includes magnetic conveyor belts extending in grooves formed in the press table and extending from adjacent the bottom of the stacking ducts to remote part storage locations.

With the arrangement of the present invention, the entire toolholding plate with stacking inserts forming the stacking ducts located therein, including the punched out parts collected in the stacking ducts and the lower punching tool, can be moved as a unit laterally out of the press. For moving this unit out of the press, hydraulically liftable rollers or mechanical displacing means including a rope, a chain, or a rack-and-pinion gear, or similar devices can be utilized according to the present invention. However, a particularly preferred embodiment of the present invention uses air cushion means for vertically supporting the unit as it is moved laterally along the press table and bracket means connected thereto.

In preferred embodiments, the units, including toolholding plates, punching tools, and stacking inserts, are pushed out of the press at the front or at the rear thereof on fixed or movable supporting brackets and, at that point (located remotely laterally of the press ram travel path and press table), can rapidly be exchanged for a new punching tool or set of punching tools with the aid of a lifting means.

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a part sectional schematic front view, taken along line I--I of FIG. 3, of a punching press constructed in accordance with a preferred embodiment of the present invention;

FIG. 2 is a part sectional schematic lateral view, taken along line II--II of FIG. 3; and

FIG. 3 is a schematic top view of the punching press of FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, like reference numerals are used throughout the various views to depict like structures.

Feed rollers 1, 2 feed a sheet-metal strip 6 between upper punching tool 4 and lower punching tool 5 of press 3. Pressing ram 7 effects punching out of parts or blanks 8, 9 from strip 6 upon each stroke of the ram 7. Since means for feeding and discharging strip 6, as well as means for driving ram 7, of conventional construction can be used with the present invention, further details of same are not included so as not to obscure the invention.

Blanks 8, 9 are passed through respective separate stacking ducts 10, 11 through the lower punching tool 5. These two stacking ducts 10, 11 extend from die portion 23 of lower tool 5 through an insert 12 in the table top or toolholder plate 13 and terminate shortly above the bottom surface of plate 13, which bottom surface of plate 13 rests on the top surface of press table 14. In order to separate the individual sheet-metal parts, the insert 12 is preferably tapered in its cross section toward the the exit area, or spreading elements schematically depicted in FIG. 1 are installed in the insert 12.

The individual sheet-metal parts 8, 9, which exit from the bottom of the respective stacking ducts 10, 11, fall onto conveyor belts 15, 16 extending at a right angle to each other. These belts 15, 16 are controlled with respect to their speed so that the sheet-metal parts 8, 9 are arranged so that they partially overlap one another and pass to respective rotatable stacking stations 19, 20 equipped with several mandrels 17, 18. Since the stacking ducts 10, 11 terminate shortly above the bottom surface of the toolholder plate 13 and since the conveyor belts 15, 16 are disposed in indentations or grooves of the press table 14 and/or in a recess of the table top 13, the entire unit including punching tools 4, 5 can be extended, together with the toolholder plate 13, laterally out of the press area on brackets 21. As can be seen from FIG. 2, this unit can then be easily exchanged with the aid of a lifting means 22. The extension (lateral outward movement) of the punching tools is facilitated by an air cushion produced by inserts in the table 14 and the brackets 21. Hydraulic piston cylinder mechanisms and rack-and-pinion gear mechanisms are also contemplated by the present invention for laterally moving the punching tool unit out of the press area onto brackets 21. Details of such mechanisms are not included herein, since one skilled in the art, given the present disclosure, will be able to modify known devices to effect the simple lateral mechanical movement and exchange of punching tool units.

While we have shown and described one embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art and we therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.