Patent Description:
As is known, when welding sheet metal, it is often necessary to weld edges of different thicknesses together.

For example, in laser welding, which is carried out on just one side of the panels, it is known to set up the welding apparatus with a special type of blankholder. Since said blankholder has a fixed reference (reference on which the surface of the panel to be welded rests) and a movable reference, it may adapt to a given range of possible panel thicknesses.

In this type of processing, the thicknesses of the panels that may be welded together may be wide-ranging, for example, panel thicknesses may vary from <NUM> to <NUM>. However, welding may also be done with different thicknesses, for example less or more than the range indicated above.

The system of the prior art, while widely used and appreciated, is not without drawbacks.

First, the blankholder of the prior art does not allow for effective clamping of a panel, the edge of which has a variable thickness. For example, the panel may be the result of a previous weld between two panels of different thickness. In this case, the edge offered for welding, which must be clamped by the blankholder, does not have a constant thickness, and therefore the blankholder can only handle the greatest thickness.

The prior art has tried to remedy this drawback with temporary support structures to be interposed between the blankholder and the surface of the panel where the thickness is less.

It is also known to make the lower gripping element fixed, while the upper gripping element is movable and adaptable to the actual thickness of the panel. In this way, however, the coplanar surfaces between the two panels on which the weld is actually made are the bottom surfaces of the panels. Since welding must therefore be carried out from the bottom up, the arrangement of the equipment and the work itself are particularly complex to manage.

In any case, the technical solution of the prior art just described does not allow for a solution to the problem related to the welding of panels having edges to be welded with two or more different thicknesses, when the upper surface is to be kept coplanar.

Thus, the technical solutions proposed by the prior art do not allow a technically and economically satisfactory procedure to be obtained.

The need to solve the drawbacks and limitations mentioned with reference to the prior art is therefore felt.

Thus, there is a need to provide a blankholder for a welding apparatus that may adapt easily also to the case wherein the panel has a variable thickness.

In addition, there is a need for a blankholder that allows the surfaces of the panels to be aligned on the upper side and not on the lower side, as is the case with apparatuses of the prior art.

There is also a need to provide a blankholder for a welding apparatus that may automatically adapt to panels of varying thickness, for example with two or more different thicknesses at the edge to be welded with another panel while keeping the top surface coplanar.

In addition, there is a need for a panel welding apparatus that comprises a blankholder with the features mentioned above.

These needs are at least partially satisfied by a blankholder for a welding apparatus according to claim <NUM>, and a welding apparatus according to claim <NUM>.

Further features and advantages of the present invention will be more readily understood from the following description of its preferred and non-limiting examples of embodiments, wherein:.

Elements or parts of elements common to the embodiments described hereinafter will be indicated with the same reference numerals.

In <FIG>, a blankholder for a welding apparatus according to the present invention is denoted with the general reference <NUM>.

The blankholder <NUM> comprises an upper gripping element <NUM> (visible, for example, in <FIG>) and a lower gripping element <NUM> having longitudinal development along a direction x. In specific technical jargon, the upper gripping element <NUM> and the lower gripping element <NUM> are also referred to as the upper crossbar and the lower crossbar, respectively. The longitudinal direction x is substantially the direction along which the upper gripping element <NUM> and the lower gripping element <NUM> extend.

The upper gripping element <NUM> and the lower gripping element <NUM> are movable relative to each other between a closed position, wherein a panel <NUM>, <NUM> is clamped between the upper gripping element <NUM> and the lower gripping element <NUM>, and an open position, wherein the panel <NUM>, <NUM> may slide between the upper gripping element <NUM> and the lower gripping element <NUM>.

The lower gripping element <NUM> comprises a lower operating surface <NUM> facing said upper gripping element <NUM>. Further, the lower gripping element <NUM> comprises a plurality of movable plates <NUM>, arranged with a gripping surface <NUM>, along X, and suitable to be moved, each independently of the others, by handling means <NUM> in a direction substantially perpendicular to the lower operating surface <NUM>, between:.

In other words, the lower gripping element <NUM> is arranged with an array of movable plates <NUM> suitable for adjusting the actual gripping surface of the lower gripping element <NUM>.

By this technical solution, the gripping distance between the upper gripping element <NUM> and the movable plates <NUM> of the lower gripping element <NUM> is therefore adjustable in such a way that the upper gripping element <NUM>. In the closed position, the upper gripping element <NUM> is always at the same height as the corresponding upper gripping element <NUM> of a second blankholder that grips the second panel to be welded.

According to a possible embodiment, the upper gripping element <NUM> is movable in approach and departure from the lower gripping element <NUM> to allow the panels to slide.

In alterative embodiments, the upper gripping element <NUM> may be fixed, assigning the clamping of the panel to the lower gripping element <NUM> and/or the movable plates <NUM>.

According to a possible embodiment, in the first position, the gripping surface <NUM> of the movable plates <NUM> may be substantially aligned with the operating surface <NUM> of the gripping element <NUM>.

In alternative embodiments, the gripping surface <NUM> of the movable plates <NUM> may be in a retracted position relative to the operating surface <NUM> of the gripping element <NUM>, or protrude therefrom by a predetermined height.

As seen, for example, in <FIG> and <FIG>, the gripping surface <NUM> of the movable plates <NUM> may be a rectangle. According to alternative embodiments, the gripping surface <NUM> may be a square, a circle, an ellipse, or, for example, any combination of straight and/or curved sections.

Movable plates <NUM> may be arranged at regular intervals along the direction X on the lower operating surface <NUM>. For example, the movable plates <NUM> may be arranged in a number of four per meter, or in a different number depending on the construction shape of said movable plates <NUM>.

According to a possible embodiment, the movable plates may be substantially rectangular, having a longitudinal dimension of approximately <NUM> and a transverse dimension of approximately <NUM>. Advantageously, the movable plates <NUM> may be spaced <NUM> apart. These measurements represent only one of the possible dimensional combinations of the constructional shape of the movable plates <NUM> and their spacing along the direction x. Other combinations are possible depending on the design requirements.

According to a possible embodiment, the lower gripping element comprises a guide jig <NUM> comprising a plurality of sliding seats <NUM>, for example bushings, for a rod <NUM>, at the end of which movable plates <NUM> are arranged at the lower operating surface <NUM>.

As seen in <FIG>, the movable plate <NUM> may be connected to its rod <NUM> by a bolted connection <NUM>.

According to a possible embodiment, each rod <NUM> may be arranged by means of a first end hinge <NUM> to a first end <NUM> of a rocker arm <NUM> according to a direction substantially perpendicular to said X-axis and having a fixed axis of rotation parallel to the X-axis, defined by a fixed central hinge <NUM>, and a corresponding linear actuator <NUM> (which is seen in the example of <FIG>) connected to a second end <NUM> of the rocker arm <NUM> by means of a second end hinge <NUM>.

The linear actuator <NUM> that defines the position of the movable plate <NUM> connected thereto via the rocker arm <NUM> may be, for example, hydraulic, pneumatic, or electric.

As shown in <FIG>, the linear actuator <NUM> may be anchored to the support frame <NUM> of the blankholder <NUM>. According to a possible embodiment, the linear actuator <NUM> may be arranged on said frame by means of an actuator hinge <NUM> such that during the actuation thereof, the actuator may rotate about the actuator hinge <NUM>.

The technical solution just described, namely the actuation of the movable plates <NUM> by means of a rocker arm <NUM>, makes it possible to move the actuation mechanism from underneath the lower gripping element <NUM> to an area away and clear of other mechanisms.

A first advantage is to move the linear actuator to a safe area away from where the panel clamping is done.

A second advantage concerns the ease of carrying out any ordinary or extraordinary maintenance operations on the handling means. In fact, the linear actuator is arranged in an easily accessible position because it is far from the area where the panels are actually picked up.

As mentioned above, the movable plates <NUM> are suitable to be moved independently of each other, due to the arrangement of independent handling means <NUM>, to adapt to the shape of a panel, which, as in the example of the panel <NUM>, presents a variable thickness in the direction x. The variable thickness is represented by the composition of the panel <NUM> with the sheets <NUM> and <NUM>.

Thus with reference to the panel shown in <FIG> resulting from welding two distinct sheets <NUM>, <NUM>, the blankholder <NUM> is suitable to shape itself to grip the edge of the panel <NUM> having two distinct thicknesses.

In this case, the movable plates <NUM>, which in use will be at the thickness of the sheet <NUM>, will protrude at a greater height than the movable plates <NUM> at the thickness of the sheet <NUM> which has a smaller thickness.

In other words, the arrangement of the movable plates at the lower gripping element makes it possible to align the upper surfaces of the panels to be welded with each other, as seen for example in <FIG>.

This description mainly refers to panels having two thicknesses; however, the same blankholder may also be successfully used with panels having more than two different thicknesses, for example three or four or more different thicknesses.

According to a possible embodiment, the blankholder <NUM> may comprise a programmable control unit <NUM>, which is operatively connected to said handling means <NUM> for actuating said handling means <NUM>, and consequently automatically adjusting the height of the movable plates <NUM>.

In other words, given the geometry of the input panel <NUM>, <NUM>, the height of the movable plates <NUM> may be adjusted accordingly in an automated manner.

As for the movement of the upper gripping element <NUM>, it may be associated with blankholder handling means <NUM> comprising guide means <NUM> and linear actuators <NUM>, <NUM>.

As seen in <FIG> and <FIG>, the blankholder handling means <NUM> may comprise guide means <NUM> comprising a guide pin <NUM> associated with each of the two ends of the upper press element <NUM>, suitable to slide in a corresponding sliding seat <NUM>.

According to a possible embodiment of the present invention, the sliding pins <NUM> may be integral with the lower press element <NUM>, and the sliding seats may be associated with the upper press element <NUM>.

According to a possible embodiment, the blankholder handling means <NUM> may comprise a pair of linear actuators <NUM>, <NUM> located at the ends of the upper press element <NUM> and the lower press element <NUM>.

Advantageously, the pair of linear actuators <NUM>, <NUM> may be placed on either side of the guide means <NUM> so that the guide means <NUM> themselves are central to the linear actuators <NUM>, <NUM>.

The present invention further relates to a welding apparatus <NUM> comprising at least one welding head <NUM>, and at least one blankholder <NUM> according to the foregoing.

A possible embodiment of a welding apparatus according to the present invention is shown, for example, in <FIG> and <FIG>.

The welding head may be of a known type, such as a laser welding head, a traditional welding head, MAG, TIG, or electrode.

According to a possible embodiment, which may be seen for example in <FIG>, the welding head may be arranged on a movable trolley <NUM>, suitable to slide on a respective guide <NUM> arranged at the structure of one of the two blankholders.

Thus, the advantages that may be achieved with the blankholder for a welding apparatus according to the present invention are apparent.

First, a blankholder has been provided that allows a panel with variable thickness to be clamped in place without the need for additional support structures.

In addition, a blankholder has been provided that may allow the opening and closing movement of the blankholder to be maintained at the lower gripping element only, while the upper gripping element remains fixed.

In addition, the blankholder according to the present invention makes it possible to automate the welding process even in the case of panels having different thicknesses.

Claim 1:
Blankholder (<NUM>) for a welding apparatus comprising an upper gripping element (<NUM>) and a lower gripping element (<NUM>) having longitudinal development along a direction (X), said upper gripping element (<NUM>) being movable between a closed position, wherein a panel (<NUM>, <NUM>) is clamped between said upper gripping element (<NUM>) and said lower gripping element (<NUM>), and an open position, wherein the panel (<NUM>, <NUM>) may slide between said upper gripping element (<NUM>) and said lower gripping element (<NUM>); said lower gripping element (<NUM>) comprising a lower operating surface (<NUM>) facing said upper gripping element (<NUM>);
characterized in that
said lower gripping element (<NUM>) comprises a plurality of movable plates (<NUM>) arranged along said direction (X), said movable plates (<NUM>) being suitable to be moved by handling means (<NUM>) in a direction substantially perpendicular to said lower operating surface (<NUM>), between a first position, wherein they do not protrude or protrude by a minimum height relative to said lower operating surface (<NUM>), and a second position, wherein they protrude relative to said lower operating surface (<NUM>) by a predetermined maximum height, said movable plates (<NUM>) being arranged with a gripping surface (<NUM>).