Patent ID: 12214405

In the following, an embodiment of the invention is described based on a bending machine in the form of a press brake. A perspective view of the press brake is shown inFIG.1, where it is designated with reference sign1. InFIG.1and also in the otherFIGS.2to6, a spatial coordinate system is shown to describe the directions of the bending machine1. The x-direction corresponds to a depth direction of the bending machine1and a workpiece to be bent is inserted in the direction of the x-direction into the bending machine1via its front side. In contrast, the y-direction is a width direction of the bending machine1. The depth direction x and the width direction z lie in one horizontal plane. The y-direction is the vertical direction and corresponds to a height direction y of the bending machine1. A primary axis of the bending machine1extends in the y-direction of the coordinate system, which is also referred to below as the working direction.

The bending machine1comprises a frame2including, among other things, two side stands3,3′ and a frame plate4. An upper beam7and a lower beam9are provided at the front side of the bending machine1. The front side of the upper beam7is designated with reference sign7aand the front side of the lower beam9is designated with reference sign9a. On the upper edge of the lower beam9there is a tool table10, on which lower tools are fastened during operation of the bending machine1. In contrast, the upper beam7has a tool receptacle8for fastening corresponding upper tools. During operation of the bending machine1, a sheet (not shown) is inserted into the space between the upper beam7and the lower beam9, and the upper beam7is then moved downwards in its working direction so that the upper tools press into the lower tools, thereby deforming the sheet. To ensure a stable stand of the bending machine during a bending process, it is anchored to the floor in its corners using corresponding anchoring means26,26′.

A hydraulic actuator is used to move the upper beam7in the working direction, which is mostly located on the top of a reinforcement plate5and that extends between the side stands3and3′. In the illustration ofFIG.1, only two hydraulic cylinders6and6′ of the actuator are visible, which are attached to the frame plate4and positioned in recesses of the upper beam7. Corresponding cylinder rods are connected to the upper beam7in this region and can cause the upper beam7to move in the direction of the primary axis, i.e. the working direction or vertical height direction y.

For measuring and monitoring a respective position of the upper beam7with respect to a reference position during a working process in which the upper beam7is moved in the direction of the primary axis (i.e. in the vertical height direction y) of the bending machine1relative to the lower beam9, two position measuring systems11,11′ are provided on the bending machine1. Although in the exemplary embodiments the bending machine1is shown with two separate position measuring systems11,11′, it is to be noted that to realize the measurement and monitoring of the position of the upper beam7it is sufficient to provide only a single position measuring system11or11′ on the bending machine.

As can be seen more clearly fromFIGS.2to4, the position measuring systems11,11′ are arranged and held at the opposite outer ends of the upper beam7and the lower beam9, wherein the position measuring systems11,11′ extend into the interior of the machine body formed by the side stands3,3′, the frame plate4and the reinforcement plate5. This can best be seen, for example, in the detailed perspective view ofFIG.3.

The position measuring system is explained in detail below with reference to the position measuring system11shown inFIGS.5and6in a detailed perspective view and a top view from the rear. The design of the position measuring system11′ shown inFIGS.2to4is structurally identical and is merely mirror-inverted with respect to the vertical x-y plane as an example.

The position measuring system11has a linearly movable measuring unit12and a stationary linear element13. The linearly movable measuring unit12has a slider21and a sensing element22fastened to the slider21. The linearly movable measuring unit12of the position measuring system11is held on the upper beam7by a connecting element14, which is resistant to deformation in the direction of the primary axis, i.e. the vertical height direction y.

The stationary linear element13, which is designed, for example, as a measuring ruler, is fastened to the lower beam, not shown inFIG.5, by means of a receptacle19resistant to deformation, so that it comes to rest next to the tool holder10in the width direction z. The stationary linear element13is mounted fixed to the lower beam9and thus to the bending machine1via the receptacle19.

When the upper beam7moves in the working direction, i.e. in the direction of the primary axis or in the height direction y, the linearly movable measuring unit12of the position measuring system11follows the movement of the upper beam7and in the process moves along the stationary linear element13. For this purpose, the slider21of the linearly movable measuring unit12is moved along the stationary linear element13via a guide25(seeFIG.6). As the linearly movable measuring unit12moves relatively along the stationary linear element13, its sensing element22moves along the stationary linear element13and enables a position of the upper beam7with respect to a predefined reference position to be determined during a working process.

The structural design of the guide25shown inFIG.6, in which an element of the slider21engages around a corresponding element of the stationary linear element, is merely exemplary in nature. Generally speaking, an internal or external guide of the slider21along the stationary linear element13, which are known in principle, would also be conceivable as an alternative.

A receptacle20is provided on the underside7bof the upper beam7to connect the connecting element14, which is resistant to deformation, to the upper beam7. The receptacle20of the upper beam7is formed in an exemplary manner in the shape of an “L”. One of the two legs of the receptacle20is detachably or non-detachably fastened to the underside7bof the upper beam7. The other of the two legs, which extends in the direction of the primary axis, i.e. in the height direction y, is used to fasten a machine side end of the connecting element14. The other, measuring system side end of the connecting element14is fastened to the slider21of the linearly movable measuring unit12.

The connecting element14is preferably fastened to the upper beam7via the receptacle20, as shown inFIGS.1to5, on a section of the upper beam7lying on the outside in the width direction z, since the section lying on the outside is subject to less deformation in comparison with other sections of the upper beam7during a bending process of the sheet metal. This, among other aspects described below, favours the accuracy of the position measuring system during a bending process.

The connecting element14is fastened to the receptacle20of the upper beam7and to the slider21by means of one or more fastening means23, e.g. screws, in each case to allow the connecting element14and the receptacle20of the upper beam7and the linearly movable measuring unit12to be detachable. This allows easy replacement of the connecting element14, depending on the existing operating conditions.

In the exemplary embodiment shown here, two fastening means23each are provided for fastening the connecting element14to the receptacle20and to the slider21. Between the respective pair of fastening means23, the connecting element has, here by way of example, a respective adjustment element24, for example in the form of a bore, to facilitate fastening and correct alignment relative to the receptacle20and the slider21. For this purpose, the receptacle20and the slider21can have projections corresponding to the adjustment elements24, which engage in the associated adjustment elements24.

The connection of the slider21, which follows the stroke of the upper beam7, to the upper beam7is made exclusively via the deformation element14, which is thus the only connecting element with an influence on detrimental deformations of the machine body. These deformations are undesirable in the width direction z and depth direction x. Measurement data of the upper beam7are only desired and relevant in the height direction y, i.e. in the direction of the primary axis.

Deformations of the machine body that have a negative effect on position measurement can occur, for example, if the upper beam7does not move in parallel to the lower beam9in the direction of the primary axis (height axis y), resulting in an inclined position of the upper beam7. When using two position measuring systems11,11′ per upper beam7, as shown inFIGS.1to4, this leads to an undesired simultaneous movement in the width direction z. A tolerance of this deformation leads to a negative bending result and damage to the position measuring systems11,11′. Similarly, such negative influences occur in the depth direction x when the machine body expands as a result of the force applied during bending and the upper beam7moves relative to the machine body.

These adverse effects are eliminated or at least largely reduced by the deformation element14. The term “deformation resistance” of the connecting element14refers to a deformation resistance in the direction of the primary axis, i.e. in the height direction y. The connecting element14is designed, for example, as a torsion element which, in contrast, is designed to be elastic, in particular spring-elastic, in the width direction z of the bending machine1and/or the depth direction x of the bending machine1. Preferably, elasticity is provided in both the width direction z and the depth direction x of the bending machine1.

Unwanted torsion or bending due to forces and deformations occurring during the bending process on the machine body and/or machine axes of the bending machine1is thus not transmitted to the stationary linear element13. The connecting element14, which is elastic in the width direction z and/or in the depth direction x of the bending machine1, decouples deformations of the machine body almost completely from the position measuring system11. Instead, only the connecting element14is deformed, in particular deformed in a reversible manner. The deformation is reversible as the connecting element returns to its original shape at the end of a working or bending process when the machine body is unloaded. This has the advantage that unwanted deformations of the machine body of the bending machine1do not influence the measurement result, but only the position of the upper beam7in the direction of the primary axis, i.e. in the height direction y, is determined via the slider21and the sensing element22fastened to it.

By design, the connecting element14has at least one partially elastic material with high fatigue strength to allow deformations in the undesired directions, namely the width direction z and/or the depth direction x, and thereby decouple them from the position measuring system11, in particular the slider21.

While the connecting element14is designed as an elastic element in the preferred directions mentioned, the receptacle19of the lower beam9and the receptacle20of the upper beam7are designed more rigidly in comparison. This arrangement almost completely decouples deformations of the machine body from the position measuring system11by deforming the connecting element14when necessary.

The connecting element14resistant to deformation is generally designed with little material in the direction of the desired elasticity, i.e. in the width direction z and/or depth direction x, in order to be able to deform elastically as a result of the application of a force. In the direction of the primary axis (height direction y), the connecting element14is characterized by a comparatively large amount of material to achieve more resistance to deformation.

In the exemplary embodiment shown in the figures, the connecting element14is designed as a flat piece that meets these requirements. Two opposite main sides14a,14bextend in the vertical x-y plane perpendicular to the width direction z. The connecting element14, which is designed as a flat piece, has a long edge extending in the depth direction x of the bending machine1. The long edge is the longest edge of the flat piece and much longer than the other two edges in the height direction y and width direction z. This can best be seen, for example, inFIG.5.

To achieve the desired elastic properties, the connecting element14has a section15with a material weakening18(FIG.6). The section15with the material weakening18has a length l15and a thickness dis. The section15with material weakening lies between two sections16,17without material weakening, which have a length l16and l17, respectively, and a thickness d16and d17. The total length l of the connecting element14is the sum of the lengths l15, l16, l17of the sections15,16,17, i.e. l=l15+l16+l17. The thicknesses d16and d17of the sections16,17without material weakening are the same in the present exemplary embodiment, i.e. d16=d17. At the same time, the thicknesses d16and d17of the sections16,17without material weakening in the present exemplary embodiment are greater than the thickness dis of the section15with material weakening, i.e. d15<d16and d15<d17.

The lengths l15, l16, l17of the sections15with material weakening and16,17without material weakening as well as the thicknesses d15, d16, d17are generally chosen depending on the bending machine1, its geometrical conditions and/or the forces occurring during the bending process. Preferably, the length l16of the section16without material weakening fastened to the receptacle20of the upper beam7is smaller than the length l17of the section17without material weakening fastened to the slider21, i.e. l16<l17.

The section15with the material weakening18can be formed with the reduced material thickness in the width direction z compared to the sections16,17having no material weakening, as is shown inFIGS.5and6. Alternatively additionally, the material weakening18can also be formed by one or more recesses (not shown in the figurative representations). In this case, the thicknesses d16and d17of the sections16,17without material weakening can correspond to the thickness dis of section15with material weakening, i.e. d15=d16=d17. The thicknesses d16and d17of the sections16,17without material weakening can alternatively be greater than the thickness d15of the section15with material weakening, i.e. d15<d16and d15<d17.

In a further alternative, the connecting element resistant to deformation can also be formed from two or more interconnected material layers using the sandwich technique. In this regard, in the section15with the material weakening18, a material interruption is provided in at least one of the other material layers (not shown in the figures). In the section15with the material weakening18, one or more recesses could also be provided.

The connecting element14can be made of spring steel or have spring steel. Alternatively or additionally, similar material with high elasticity can be used.

It is expedient that the material of the connecting element resistant to deformation and its receptacles19,20on the upper beam7and the lower beam7have thermal conductivity. This allows a parallel expansion of the position measuring system11and the machine body.

The embodiment of the invention described in the foregoing provides a number of advantages.

The fastening means23used to hold the connecting element14resistant to deformation to the upper beam7and the linearly movable measuring unit12make it possible to have a modular system in which the connecting element14can be quickly replaced in a simple manner when operating conditions change. For example, connecting elements resistant to deformation made of different materials with different material properties can be used if particularly high deformations of the machine body are expected or if the geometrical conditions change, e.g. in the case of greater bending lengths or forces. In addition, the connecting element14can be quickly replaced in the event of damage. This can reduce machine downtime.

The use of the connecting element14resistant to deformation does not require any lubrication or special maintenance measures, thus providing a reliable position measuring system by simple and inexpensive means.

The connection of the connecting element on the upper beam7and the linearly movable measuring unit12ensures freedom from play between the stationary linear element13and the linearly movable measuring unit12, which moves relative to it, allowing for an optimum position control in the direction of the primary axis. Oscillation as a result of changing control parameters cannot occur with a connection that is free from play. This increases the measurement accuracy.

LIST OF REFERENCE SIGNS

1Bending machine2Frame3,3′ Side stand4Frame plate5Reinforcement plate6,6′ Hydraulic cylinder7Upper beam7aFront side of the upper beam7b,7b′ Underside of upper beam8Tool receptacle9Lower beam9aFront side of the lower beam10Tool holder11,11′ Position measuring system12Linearly movable measuring unit13Stationary linear element14Connecting element14aMain side of the connecting element14bMain side of the connecting element15Section with material weakening16Section without material weakening17Section without material weakening18Material weakening19Receptacle of the lower beam920Receptacle of the upper beam721Slider22Sensing element23Fastening means (e.g. screw)24Adjustment element (e.g. bore)25Guide26,26′ Anchoring meansl Length of connecting element14l15Length of section15l16Length of section16l17Length of section17d15Thickness of section15d16Thickness of section16d17Thickness of section17