The invention particularly concerns stamping of profile bars used in the industry of constructing curtain walls or outer framework structure around buildings for supporting external protective glass panes, as now dominant in modern office buildings all over the world.

A typical curtain walls bar B (see Fig. 1) generally comprises a web portion denoted W, a pair of up-right legs L, and a central up-right rib R.

These bars have to be processed in such a way that a plurality of cut-outs C have to be removed at predertemined distances, usually at both sides, but sometimes only at one side thereof. The length of the processed bars is considerably large, usually about 5 to 8 meters.

Punching apparatus for this purpose has already been designed.

Hence, in Fig. 2 there is schematically shown a prior art apparatus 10 which essentially comprises a supporting guide rail 12 on which profile bar 14 is supported during punching, as well as for sliding it along the predetermined distances between successive punching operations.

The profile bar 14 is pressed against the guide rail 12 during the punching operation by a pneumatic cylinder unit 16.

A pair of stamping dies 17 and 18 are provided, operable in the outward direction by pneumatic cylinder units denoted 20 and 22, respectively. As further schematically shown, the stamping is performed against matrixes 24,26 as customary in the art. A pneumatic control panel is provided (not shown) whereby the operator can actuate either or both of the pneumatic cylinders 20 and 22, as required for the particular job at hand.

These prior art apparatus, although almost exclusively used around the world are inefficient or otherwise disadvantageous in any or all of the following respects: First-the need for a pair of cylinders and auxiliary controls is cumbersome, expensive and space-consuming; secondly-due to the particular construction of the apparatus, the maneuverability of the processed profile bars 14 is inconvenient; and thirdly, due to the inherent structure, the vision field of the operator is partly obstructed, presenting certain difficulty in placing bars at the exact position for punching the cut-out pieces C at the precise selected location.

It is thus the general object of the present invention to provide an apparatus that will be less expensive and more convenient to operate.

It is a further object of the invention to provide an apparatus employing only one pneumatic (or hydraulic) piston for operating one, the other, or both of the stamping dies.

It is a still further object of the invention to obtain an amplification of the piston force, thereby saving on measurements and/or pressure needed for their effective operation.

SUMMARY OF THE INVENTION Thus provided according to the present invention is a press punching apparatus particularly for stamping marginal sections off U-shaped profile elongated bars having a web and two upright legs, comprising support means for firmly supporting the bar by its web during the stamping operation, at least one stamping die located within the bar opposite the leg portion which is to be stamped, slidable mounting means for the stamping die, enabling the displacement of the die for effecting the stamping operation of the section of the respective bar leg, means for the displacement of the stamping die, which comprise a cylinder and piston unit operating piston rod, wedge lever means operatively associated with the stamping means, and means for coupling the piston rod to the wedge lever means so that by operating the cylinder and piston unit, the stamping die becomes displaced to complete the stamping of a respective section of the bar leg.

Preferably the apparatus will comprise an additional stamping die located within the bar opposite to the other leg portion, and with associated displacing means operable by the cylinder and piston unit.

The wedge lever means preferabiy comprise a block operatively connected to the piston rod, to reciprocate in a direction normal to that of stamping die, a slot formed in the block, extending at an angle relatively to the said direction, and a bolt pin selectively insertable through the slot to establish the transforming of the piston rod reciprocating movement to movement of the stamping die.

BRIEF DESCRIPTION OF THE DRAWINGS These and additional features and advantages of the present invention will be more clearly understood in the light of the following description of a preferred embodiment thereof, given by way of example only, with reference to the accompanying drawings, wherein- Fig. 1 is a three-dimensional view of a typical profiled curtain wall construction bar; Fig. 2 is a schematic representation of a prior art punching apparatus; Figs. 3 is a schematic representation of a punching apparatus according to principles of the present invention in a non-operative position; Fig. 4 is a section taken along line IV-IV of Fig. 3; Fig. 5 is a view taken along line V-V of Fig. 3; and Fig. 6 shows the apparatus of Fig. 3 in its operating, cutting position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Fig. 3 of the attached drawings it will be noted that, similarly to the prior art apparatus of Fig. 2, a guide rail 30 is provided, configured to support the processed bar B, which is also clamped during punching by pneumatic cylinder and piston unit 32; so are conventionally provided stamping matrixes 34 and 36 associated with stamping dies 38 and 40, respectively.

Rather then connecting the stamping dies directly to pneumatic pistons as in the prior art apparatus, the following arrangement is applied. The stamping dies 38 and 40 are respectively mounted to carriage members 42, 44 which are suitably supported for reciprocating sliding movement by housings 46 and 48 (one being shown in cross-section in Fig. 4).

Since the construction is symmetrical, reference shall be made to the right-hand side of the apparatus only, being understood that the left-hand side is a mirror-image thereof.

A driving mechanism generally designated 50 is provided, comprising pus-pull rod 52, reciprocally movable by being coupled by bracket 54 to piston rod 56 of fixedly supported pneumatic cylinder 58. The rod 52 is connected to a cam block 60, preferably via screw-threaded adjusting tie-rod 52a.

The cam block 60 is slidable vertically within the housing 46, and is formed with an incline slot 62. The block is selectively coupled to the carriage member 42 by a pin bolt 64 (legs 42a and 42b). The inclined slot 62 thus constitute wedge-lever means, converting the vertical movement of the block 60 into a horizontal movement of the carriage member 42.

It will be readily understood in the light of the foregoing description that the operation of the apparatus proceeds as follows:- Once processed bar B is placed on the support 30 and press-clamped by the piston 32, at the correct location ready for operation, the piston 58 receives a command to push the piston rod 56 down. Hence, (see Fig. 6) pus-pull rod 52 will be pulled down, bringing about a movement of the carriage member 42 to the right due to the movement of the pin bolt 64 along the slot 62. It will be also appreciated that a certain amplification factor of the piston force is achieved in proportion to the inclination angle of the slot 62 (less a certain friction force which is inevitably generated).

The stamping die 38 will thus move to the right thereby performing the stamping operation.

The same will apply to the left-hand stamping die 40, however in the opposite direction.

Should a punching operation be completed only at one (the left) side of the bar B, the pin bolt 64 will be pulled out of slot 62 (using handle 64a as

shown in phantom lines in Fig. 4) thereby neutralizing the movement of the respective carriage 42 and no punching operation will be performed.

It should now be clear that the provision of the screw-threaded adjusting tie-rod 52a allows to achieve fine adjustments of cutting depth, dominated by considerations such as the wall thickness of the processed bar B.

It has thus been established that the novel apparatus design is superior to the prior art apparatus in the respects hereinabove specified.

While the above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as exemplification of the preferred embodiment. Those skilled in the art will envision other possible variations that are within its scope. Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents.