EP3010708B1 - Method for bending the machine bed of a stamping press, and stamping press - Google Patents

Description

Technical area

The present invention relates to a method for buckling the machine bed of a punch press for at least partial compensation of a punching force-induced deflection in the punching operation and various punch presses for performing the method, according to the preambles of the independent claims.

State of the art

For the industrial production of stamped parts made of sheet metal today fast-running stamping machines are used, in which an upper tool part with punches to a certain stroke on a lower tool part with dies is moved to and thus cuts and shapes on sheet metal strip performs. Today's so-called follow-cutting tools, which usually comprise a large number of modules that perform various tasks such as cutting, bending, forming and embossing, require ever longer tool installation spaces.

Accordingly, in the last three decades, the length of the tool installation space of stamping machines has practically doubled while maintaining tonnage, which leads to a corresponding increase in the moving and stationary masses due to the longer components and at the same time to problems with the stiffness of the press structure, since the Length increase typically decreasing stiffness of some critical components, in particular of the machine bed, due to limited space can not be arbitrarily compensated by corresponding cross-sectional enlargements.

This in turn gives rise to the problem that it increases with increasing length of the tool installation space It is becoming increasingly difficult to keep the deformations of the press structure, and in particular the deflection of the machine bed under the punching load, which should be as low as possible for high process precision and low tool wear. In machine beds with a breakthrough for the removal of stamped parts and waste, as used in today's punching machines, resulting in the punching operation, a spatial deflection of the machine bed, as more or less is punched over this breakthrough, whereby the deflection in the area of the breakthrough greater is as in the areas of the longitudinal sides of the machine bed. In particular, in the event that punching operations are carried out in the rather unusual punching direction from back to front, these deflections represent a major problem.

In order to reduce or compensate for the deflection due to the process load in machine beds or platen without breakthrough, it is known from the prior art to warp the machine bed or platen against the direction of deflection, possibly such that this warping canceled by the process load just is, or support the platen dynamically with variable-height support elements so on under the load possibly bending support structure that the platen itself under the punching load undergoes no significant deflection.

That's how it is EP 0 653 254 A2 a press is known in which support units are arranged between the press bed and the platen, which are adjustable in height. These support units can be mechanical, electromechanical or hydraulic type and operated by a controller such that a deformation of the platen is counteracted under the working pressure of the press. It is also possible, with these support units to cause a protrusion of the platen to compensate for tool types.

Out DE 44 15 577 A1 is a machine table with a platens for presses in the field of forming known, in which between a base plate and the platen, a plurality of hydraulic compensation pistons are arranged. There are displacement and bending sensors and a suitable control available for controlling the pressure in the compensation piston such that a deformation of the platen is counteracted under the working pressure of the press.

From EP 0 653 254 A2 and DE 44 15 577 A1 known systems generally have the disadvantage that they are mechanically complex and therefore expensive and expensive to manufacture and maintain, and that they due to the design with multiple selective support of the platen in the punching direction on an underlying support structure for the required height a relatively small allow structural rigidity. For the variants with hydraulic support units / compensation piston is added as a further disadvantage that the supporting oil cushion in the punching force direction has a low rigidity and the inevitable deformation of the entire hydraulic system under the oil pressure generated by the support pressure to a compression of the support under the punching load. For the variants in which a deflection of the platen is to be prevented by means of dynamic height adjustment of support elements, it should be said that these, if feasible at reasonable cost, at most suitable for very slow forming processes, but not for fast punching machines for processing metal strips in progressive die technique.

Out DE 100 10 197 A1 a press is known in which the machine bed by biasing in the lower region of the machine bed passing through in the longitudinal direction Tie rods can be warped in the direction of the press ram in order to correct a deflection of the press bed or to produce a bulge in the load-free state. There is a control by means of which the pretensioning of the tie rods can be regulated as a function of determined deflections. This system largely avoids the aforementioned disadvantages of the two systems mentioned first.

Out CH 542 713 A a punch press is known in which the press ram and the machine table each have oil-filled cavities, which are part of a common oil circuit to effect a temperature compensation between these components.

Out EP 0 355 730 A2 However, one of the known systems solves the above-mentioned problem of the punching force-related spatial deflection in machine beds with a breakthrough for the removal of stampings and waste is a method for the compensation of temperature-induced deformations.

Presentation of the invention

It is therefore the task of providing a technical solution that makes possible an at least partial compensation of a punching force-induced spatial deflection of the machine bed both in the longitudinal and in the transverse direction of the machine bed in punch presses with a machine bed with breakthrough for the removal of stampings and waste and does not have the aforementioned disadvantages of the prior art or at least partially avoids them.

This object is achieved by the method and the stamping presses according to the independent patent claims.

In accordance with these, a first aspect of the invention relates to a method of warping the machine bed of a punch press which provides a breakthrough for removal of stamped parts and waste, for at least partial compensation of a punching force-related deflection of the machine bed in the punching operation. According to the invention, forces acting transversely to the punching force direction are introduced into the machine bed and / or forces acting transversely to the punching force direction are generated in the machine bed, causing the machine bed to buckle in the direction of the press ram in such a way that it is more warped in the area adjacent to the breakthrough than in the areas adjacent to its long sides.

By means of the method according to the invention, perforated machine beds of stamping presses can be spatially pre-formed with a very low investment outlay for the purpose of at least partial compensation of punching force-related deflections.

In a preferred embodiment of the method, the machine bed is set in its lower region under compressive stress with extending in its longitudinal direction tie rods, for Verwölben same in the direction of the press ram to. This method of generating the deformation forces has the advantage that it is delay-free and the deformation forces and the resulting deformations are well controlled.

It is preferred that the tie rods are arranged such that they pass through the machine bed in its lower region. This has the advantage that virtually no additional space is needed.

Advantageously, in these embodiments, in particular symmetrically on both sides of the opening in each case a tie rod is arranged, such that the tie rods each have a smaller distance from the opening than the respective longitudinal side of the machine bed. This can be achieved in a simple manner, a greater warping in the area of the breakthrough than in the area of the long sides.

In a further preferred embodiment of the method, a temperature gradient is generated within the machine bed or within a support structure formed with the machine bed for the lower tool parts of the press tool, by means of which the machine bed, due to locally different thermal expansion or heat shrinkage of the machine bed and / or or different thermal expansion or heat shrinkage of components of the support structure formed therewith for the lower tool parts to be arched in the direction of the press ram. This method of generating the deformation forces has the advantage that it can be used without having to deviate from existing and proven structural concepts. This is of particular importance in the field of high-speed, high-speed stamping presses, as it often requires years of detailed work to optimize the press structures with regard to their dynamic behavior and their service life. In addition, this embodiment of the inventive method can be implemented with little effort even with existing presses.

In this case, in a preferred embodiment of the method, the temperature gradient causing the warpage is generated by heating the machine bed in the region of its side facing the press ram, wherein it is further preferred that heating is more intense in the vicinity of the boundaries of the opening than in the vicinity of the longitudinal sides of the press machine bed. Local heating represents a particularly simple and economical method for generating the temperature gradient, especially as waste heat is often available free of charge in production plants.

Alternatively or additionally, it is preferable to generate the temperature gradient by cooling the machine bed in the region of its side facing away from the press ram, wherein it is further preferred that more cooling is achieved in the vicinity of the boundaries of the opening than in the vicinity of the longitudinal sides of the machine bed. This method is particularly useful when these machine components are relatively warm during operation and can be locally cooled in this way, without leading to dew point falls with condensation on the machine parts.

The introduction of heat and / or cold in the components can be done in various ways.

In a preferred embodiment of the method, flow channels arranged within the machine bed are flowed through by a heated or cooled, gaseous or liquid medium.

For this purpose, for example, heated lubricating oil of a lubricating oil circuit of the press can be used, which is guided by the flow channels prior to cooling. The latter method has the advantage that no additional energy is needed for heating.

In a further preferred embodiment of the method, electrical heating elements are arranged within the machine bed and supplied with electric current for generating heat. In this variant, there is the advantage that with very simple means a precise and adapted to the particular operation control of the temperature gradient is possible.

In yet another preferred embodiment of the method, the temperature gradient is generated by arranging on the machine bed a clamping plate which is heated.

In another preferred embodiment of the method, a platen is arranged on the machine bed and a heating device is arranged between the machine bed and the platen, which is heated.

In this case, according to a preferred variant of these two last-mentioned embodiments, the machine bed is heated by means of the heated platen or by means of the arranged between the machine bed and the platen heater on its side facing the plunger, with the result that there is a warping of the machine bed in the direction to come to the press ram.

According to another preferred variant of these two latter embodiments, the Platen rigidly connected to the machine bed, directly or indirectly via the heater. In this variant, the warping of the machine bed in the direction of the press ram can also occur exclusively as a result of an initiation of shear forces generated by a thermal expansion of the platen in the side facing the plunger of the machine bed, or due to a combination of shear forces generated by a thermal expansion of the platen in the side facing the plunger of the machine bed with a heating of the machine bed by the platen or the heater.

In yet another preferred embodiment of the method, the warpage of the machine bed is adjusted in dependence on parameters of the stamping process, e.g. as a function of a previously calculated or product-specific punching force or of a maximum punching force measured during operation. Further, it is preferred that the warpage be adjusted during the intended operation of the press. In this way, the respective operating situation and any changes, for example due to increasing tool wear, are particularly well taken into account.

A second aspect of the invention relates to a punch press which is suitable for carrying out the method according to the first aspect of the invention. The punch press has a machine bed and a press ram working against the machine bed. The machine bed of the punch press has an opening for the removal of stamped parts and waste. Further, the punch press comprises means for buckling the machine bed in the direction of the press ram to by acting transversely to the punching force direction forces in the machine bed and / or by generating forces acting transversely to the punching force forces in the machine bed. In this case, these funds are designed such that they Machine bed in the area adjacent to the opening more pronounced warping than in the areas adjacent to the longitudinal sides of the machine bed.

This makes it possible to provide high-speed, high-speed, high-speed stamping presses with perforated machine beds at low cost.

The means for arching the machine bed include tie rods extending longitudinally of the machine bed for compressing the machine bed in its lower portion to buckle the machine bed toward the press ram. This method of generating the deformation forces has the advantage that it is delay-free and the deformation forces and the resulting deformations are well controlled.

In a preferred embodiment of the stamping press, the tie rods are arranged such that they pass through the machine bed in its lower region. As a result, virtually no additional space is needed.

Advantageously, in these embodiments, a tie rod is arranged on both sides of the opening, in particular in a symmetrical configuration, such that the tie rods each have a smaller distance from the opening than the respective longitudinal side of the machine bed. This can be achieved in a simple manner, a greater warping in the area of the breakthrough than in the area of the longitudinal sides.

A third aspect of the invention relates to a punch press which is suitable for carrying out the method according to the first aspect of the invention. The punch press has a machine bed and a press ram working against the machine bed. The machine bed of the punch press has an opening for the removal of stamped parts and waste. Furthermore, the punch press comprises means for buckling the machine bed in Direction of the press ram to by acting transversely to the punching force acting forces in the machine bed and / or by generating forces acting transversely to the punching force forces in the machine bed. In this case, these means are designed such that they warp the machine bed in the area adjacent to the opening more than in the areas adjacent to the longitudinal sides of the machine bed.

The means for arching the machine bed are designed for the targeted generation of a temperature gradient within the machine bed or within a supporting structure formed with the machine base for the lower tool parts, by means of which the machine bed, due to locally different thermal expansion or heat shrinkage of the machine bed and / or different thermal expansion or Heat shrinkage of components of the support structure formed therewith for the lower tool parts, in the direction of the press ram can be warped. This method of generating the deformation forces has the advantage that it can be realized without having to deviate from existing and proven structural concepts. As already mentioned, this is of particular importance in the field of high-speed, high-speed stamping presses, since it often takes years of detailed work to optimize the press structures with regard to their dynamic behavior and their service life. In addition, this embodiment can be implemented with little effort even with existing presses.

Within the machine bed flow channels are arranged, which can be flowed through in the intended operation of the press with a heated or cooled, gaseous or liquid medium, for generating the temperature gradient.

Next facilities are available with which in the normal operation of the press heated lubricating oil of a lubricating oil circuit of the press through the Flow channels can be performed to generate the temperature gradient.

This solution is energetically particularly advantageous because virtually no heating energy is needed to provide the heat.

In a preferred embodiment of the stamping press, the means for warping the machine bed are designed such that the machine bed can be heated in the region of its side facing the press ram to effect the warping due to uneven heating with corresponding uneven thermal expansion of the same. It is further preferred that with these means the machine bed can be heated to a greater extent in the vicinity of the boundaries of the opening than in the vicinity of its longitudinal sides.

Alternatively or additionally, the means for buckling the machine bed are designed such that with them the machine bed in the region of its side facing away from the press ram can be cooled to effect the warping due to uneven cooling with the same uneven spatial shrinkage of the same. It is further preferred that with these means, the machine bed can be cooled in the vicinity of the boundaries of the opening stronger than in the vicinity of its longitudinal sides.

In a further preferred embodiment of the stamping press, electrical heating elements are arranged inside the machine bed, in particular resistance heating elements, which can be supplied with electrical current in the intended operation of the press, for generating the temperature gradient causing the warping. This construction allows a particularly well controllable generation of the temperature gradient.

Preferably, one or more flow channels and / or electrical heating elements are on either side of the opening of the machine bed within arranged the machine bed, preferably such that each side of the sum of the distances of the flow channels and / or heating elements for breakthrough is smaller than the sum of the distances between the flow channels and / or heating elements to the respective longitudinal side of the machine bed. It is further preferred that the flow channels and / or heating elements are arranged symmetrically to both sides of the opening. As a result, the desired greater warping of the machine bed in the area of the breakthrough can be brought about in a simple manner.

A fourth aspect of the invention relates to a punch press which is suitable for carrying out the method according to the first aspect of the invention. The punch press has a machine bed and a press ram working against the machine bed. The machine bed of the punch press has an opening for the removal of stamped parts and waste. Further, the punch press comprises means for buckling the machine bed in the direction of the press ram to by acting transversely to the punching force direction forces in the machine bed and / or by generating forces acting transversely to the punching force forces in the machine bed. In this case, these means are designed such that they warp the machine bed in the area adjacent to the opening more than in the areas adjacent to the longitudinal sides of the machine bed.

The means for arching the machine bed are designed for the targeted generation of a temperature gradient within the machine bed or within a supporting structure formed with the machine base for the lower tool parts, by means of which the machine bed, due to locally different thermal expansion or heat shrinkage of the machine bed and / or different thermal expansion or Heat shrinkage of components of the support structure formed therewith for the lower tool parts, in the direction of the press ram can be warped. This method of generating the Deformation forces have the advantage that they can be realized without having to deviate from existing and proven structural concepts. As already mentioned, this is of particular importance in the field of high-speed, high-speed stamping presses, since it often takes years of detailed work to optimize the press structures with regard to their dynamic behavior and their service life. In addition, this embodiment can be implemented with little effort even with existing presses.

In this case, the punch press arranged on its machine bed on a platen, which during the normal operation of the press, in particular electrically, is heated.

The platen is so connected to the machine bed that the platen when heated, the machine bed heated on its side facing the plunger, to produce the warping causing temperature gradient It is further preferred that with the platen, the machine bed in the vicinity of the boundaries of the opening can be heated more than in the vicinity of its longitudinal sides.

A fifth aspect of the invention relates to a punch press which is suitable for carrying out the method according to the first aspect of the invention. The punch press has a machine bed and a press ram working against the machine bed. The machine bed of the punch press has an opening for the removal of stamped parts and waste. Further, the punch press comprises means for buckling the machine bed in the direction of the press ram to by acting transversely to the punching force direction forces in the machine bed and / or by generating forces acting transversely to the punching force forces in the machine bed. In this case, these means are designed such that they the machine bed in the area adjacent to the breakthrough more warping than in the areas adjacent to the longitudinal sides of the machine bed.

The means for arching the machine bed are designed for the targeted generation of a temperature gradient within the machine bed or within a supporting structure formed with the machine base for the lower tool parts, by means of which the machine bed, due to locally different thermal expansion or heat shrinkage of the machine bed and / or different thermal expansion or Heat shrinkage of components of the support structure formed therewith for the lower tool parts, in the direction of the press ram can be warped. This method of generating the deformation forces has the advantage that it can be realized without having to deviate from existing and proven structural concepts. As already mentioned, this is of particular importance in the field of high-speed, high-speed stamping presses, since it often takes years of detailed work here to optimize the press structures with regard to their dynamic behavior and their service life. In addition, this embodiment can be implemented with little effort even with existing presses.

In this case, the punch press arranged on its machine bed on a platen, which during the normal operation of the press, in particular electrically, is heated.

The platen is shear-stiffly connected to the machine bed, so that when heating the platen comes to a heating and corresponding expansion of the platen, which as a result of the thrust-rigid coupling of the same to the machine bed, the warping of the machine bed is effected in the direction of the press ram.

In a preferred embodiment, a thermal insulation layer is arranged between the clamping plate and the machine bed, which provides a reduction the heat transfer from the platen causes the machine bed.

Here, in a preferred variant, this thermal insulation layer in the areas adjacent to the longitudinal sides of the platen and the machine bed, between the platen and the machine bed available, while in the areas adjacent to the breakthrough, a layer between the platen and the machine bed is present, which has a much better thermal conductivity, to favor a heat transfer from the platen to the machine bed in these areas. Also by this measure can be easily cause the desired greater warping of the machine bed in the breakthrough.

According to a preferred embodiment of the stamping press, the clamping plate is connected to the machine bed in such a way that, when it is heated, it heats the machine bed on its side facing the plunger. By this configuration, when the platen is heated, warpage of the machine bed by the thrust forces introduced from the platen into the machine bed is effected in combination with the nonuniform thermal expansion thereof resulting from the uneven heating of the machine bed.

A sixth aspect of the invention relates to a punch press which is suitable for carrying out the method according to the first aspect of the invention. The punch press has a machine bed and a press ram working against the machine bed. The machine bed of the punch press has an opening for the removal of stamped parts and waste. Further, the punch press comprises means for arching the machine bed in the direction of the press ram to by acting transversely to the punching force forces in the machine bed and / or by generating transverse to the punching force direction acting forces in the machine bed. In this case, these means are designed such that they warp the machine bed in the area adjacent to the opening more than in the areas adjacent to the longitudinal sides of the machine bed.

The means for arching the machine bed are designed for the targeted generation of a temperature gradient within the machine bed or within a supporting structure formed with the machine base for the lower tool parts, by means of which the machine bed, due to locally different thermal expansion or heat shrinkage of the machine bed and / or different thermal expansion or Heat shrinkage of components of the support structure formed therewith for the lower tool parts, in the direction of the press ram can be warped. This method of generating the deformation forces has the advantage that it can be realized without having to deviate from existing and proven structural concepts. As already mentioned, this is of particular importance in the field of high-speed, high-speed stamping presses, since it often takes years of detailed work to optimize the press structures with regard to their dynamic behavior and their service life. In addition, this embodiment can be implemented with little effort even with existing presses.

In this case, the punch press on a arranged on its machine bed platen, wherein between the machine bed and the platen, a particular electric heating device is arranged, which can be operated during the intended operation of the press.

In this case, the heating device arranged between the clamping plate and the machine bed is connected to the machine bed in such a way that the heating device, when operated, heats the machine bed on its side facing the ram, for generating the Warping effecting temperature gradient. It is further preferred that with the heater, the machine bed can be heated more near the limits of the opening than in the vicinity of its longitudinal sides.

A seventh aspect of the invention relates to a punch press which is suitable for carrying out the method according to the first aspect of the invention. The punch press has a machine bed and a press ram working against the machine bed. The machine bed of the punch press has an opening for the removal of stamped parts and waste. Further, the punch press comprises means for buckling the machine bed in the direction of the press ram to by acting transversely to the punching force direction forces in the machine bed and / or by generating forces acting transversely to the punching force forces in the machine bed. In this case, these means are designed such that they warp the machine bed in the area adjacent to the opening more than in the areas adjacent to the longitudinal sides of the machine bed.

The means for arching the machine bed are designed for the targeted generation of a temperature gradient within the machine bed or within a supporting structure formed with the machine base for the lower tool parts, by means of which the machine bed, due to locally different thermal expansion or heat shrinkage of the machine bed and / or different thermal expansion or Heat shrinkage of components of the support structure formed therewith for the lower tool parts, in the direction of the press ram can be warped. This method of generating the deformation forces has the advantage that it can be realized without having to deviate from existing and proven structural concepts. As already mentioned, this is particularly outstanding in the field of high-speed, high-speed stamping presses Meaning, as it often takes years of detailed work to optimize the press structures in terms of their dynamic behavior and their service life. In addition, this embodiment can be implemented with little effort even with existing presses.

In this case, the punch press on a arranged on its machine bed platen, wherein between the machine bed and the platen, a particular electric heating device is arranged, which can be operated during the intended operation of the press.

The platen is shear-stiffly connected to the machine bed, directly or indirectly via the heater, so that when heating the platen or when operating the heater essentially comes to a heating and corresponding expansion of the platen, which due to the thrust-rigid coupling of the same to the machine bed the warping of the machine bed in the direction of the press ram is effected.

In a preferred embodiment of the stamping press, the heating device arranged between the clamping plate and the machine bed is connected to the machine bed in such a way that the heating device, when operated, heats the machine bed on its side facing the plunger in order to produce the temperature gradient causing the warping. It is wieter preferred that with the platen or the heater, the machine bed can be heated in the vicinity of the boundaries of the opening stronger than in the vicinity of its longitudinal sides.

The use of heated platens or arranged between the machine bed and a platen heaters is particularly well suited for cost-effective retrofitting of existing stamping presses.

Advantageously, the means for buckling the machine bed are adjustable, preferably during the intended operation of the press, so that a targeted and adapted to the particular operating case setting the warping of the machine bed is possible.

For this purpose, the punch press preferably has a press control, with which the warpage of the machine bed, preferably automatically, depending on parameters of the punching process is adjustable, preferably in response to a calculated or product specific punching force or measured during operation maximum punching force, preferably during the intended operation of the press. As a result, a process control with automatic adjustment of the warping of the machine bed to the respective operating conditions is possible.

Brief description of the drawings

• Fig. 1 eine Schnittdarstellung durch einen Stanzautomaten mit Oberantrieb;
• Fig. 2 einen Schnitt durch das Maschinenunterteil des Stanzautomaten entlang der Linie X-X in Fig. 1;
• Fig. 3 eine Darstellung wie Fig. 2 durch die Unterstruktur eines ersten erfindungsgemässen Stanzautomaten;
• Fig. 4 eine Darstellung wie Fig. 2 durch die Unterstruktur eines zweiten erfindungsgemässen Stanzautomaten;
• Fig. 5 eine Darstellung wie Fig. 2 durch die Unterstruktur eines dritten erfindungsgemässen Stanzautomaten; und
• Fig. 6 einen Schnitt entlang der Linie A-A in Fig.5.

Further preferred embodiments of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

• Fig. 1 a sectional view through a stamping machine with top drive;
• Fig. 2 a section through the machine base of the punching machine along the line XX in Fig. 1 ;
• Fig. 3 a representation like Fig. 2 through the substructure of a first punching machine according to the invention;
• Fig. 4 a representation like Fig. 2 through the substructure of a second punching machine according to the invention;
• Fig. 5 a representation like Fig. 2 through the substructure of a third punching machine according to the invention; and
• Fig. 6 a section along the line AA in Figure 5 ,

Ways to carry out the invention

In Fig. 1 a punching machine with top drive is shown, wherein the machine head is shown cut with the drive 1, the plunger 2 and the slide guides 3 in the longitudinal direction, while the machine base is shown with the clamping plate 4 and the machine bed 5 is not cut.

Fig. 2 shows a section through the machine base of the punching machine along the line XX in Fig. 1 , as it is formed according to the prior art. As can be seen, the clamping plate 4 is arranged on the machine bed 5 and has in the center an opening 6a, which opens in the direction of gravity in a centrally arranged in the machine bed 5 opening 6b. The openings 6a, 6b are used to carry away punched parts and waste from the punching zone.

As can also be seen, the machine bed 5 forms a closed cavity 7a, 7b on both sides of the opening 6b, which serves as a tank for the lubricating oil 8 of the lubricating oil circuit of the stamping machine. In operation, the machine bed 5 is heated more strongly by the warm lubricating oil 8 in its lower region than in its upper region, whereby it cambers already without punching force load by different thermal expansion downwards. Under the burden The punching force causes an additional bending of the machine bed 5 during operation, and consequently a corresponding loss of precision and increased tool wear.

Fig. 3 shows a section through the machine base of the punching machine along the line XX in Fig. 1 as formed according to a first embodiment of the invention. As can be seen, the outer contours of the clamping plate 4 and the machine bed 5 are identical here as in the embodiment according to Fig. 2 , However, the internal structure of the machine bed 5 clearly differs from that Fig. 2 , In the present case, the machine bed 5 forms on both sides of the opening 6b two superimposed closed cavities 9a, 9b; 9c, 9d, of which only the upper 9a, 9c serve as a tank for the lubricating oil 8 of the lubricating oil circuit of the punching machine. Above the cavities 9a, 9b; 9c, 9d, the machine bed 5 has three flow channels 10a, 10b, 10c arranged side by side on both sides of the opening 6b; 10d, 10e, 10f, of which in each case the flow channels 10c, 10d closest to the aperture 6b have a significantly larger flow cross-section than the other flow channels 10a, 10b, 10e, 10f. The flow channels 10a-10f are flowed through in operation by the heated lubricating oil 8 of the lubricating oil circuit of the stamping machine, which is then passed into the cavities 9a, 9c, from where it with the lubricating oil pump of the lubricating oil circuit, possibly after passing through a cooler, again to the lubrication points of the Punching machine is performed. The warm lubricating oil 8 is first passed through the flow channels 10c, 10d closest to the opening 6b, then through the middle flow channels 10b, 10e and finally through the outer flow channels 10a, 10f, where it gives off heat to the machine bed 5. As a result, the machine bed 5 is in operation in its upper Warmer area warmed more than in its lower portion, causing it due to differential thermal expansion upwards and thus warped in the direction of the plunger 2.

In this case, the machine bed 5 due to the order of flow through the flow channels and the different flow channel cross-sections in the areas adjacent to the opening 6b is heated more than in the areas of its longitudinal sides, resulting in a greater Verwölbung the same upwards in the areas adjacent to the opening 6b leads than in the areas of its long sides.

The clamping plate 4, which is fastened with a plurality of screws on the machine bed 5, follows the warping of the machine bed 5. In operation, under the stress of the punching force to compensate for this thermal expansion-related warpage, so that the machine bed 5 ideally under maximum Stanzkraftbelastung both longitudinally and transversely flat, ie not warped or not bent, is. As a result, a loss of punching precision and increased tool wear can be effectively counteracted.

Fig. 4 shows a section through the machine base of the punching machine along the line XX in Fig. 1 as formed according to a second embodiment of the invention. As can be seen, here the outer contours of the clamping plate 4 and the machine bed 5 are identical as in the embodiment according to Fig. 2 , And also the internal structure of the machine bed 5 is identical to that of the machine bed Fig. 2 , However, here an intermediate plate 11 is arranged between the clamping plate 4 and the machine bed 5 with a plurality of flow channels 10a-10l, which are flowed through in operation by a hot water circuit, eg from a recooling device of the lubricating oil circuit of the punching machine. This is the warm water first through the flow channels 10d, 10e, 10h, 10i closest to the boundaries of the opening 6b in the machine bed 5, then through the inner and middle flow channels 10c, 10f, 10g, 10j arranged next to them and finally through the outer flow channels 10a, 10b, 10k, 101. In this case, the intermediate plate 11 is heated by the hot water circuit and in turn heats the abutting contact surfaces of the machine bed 5 and the platen 4. This in turn, the machine bed 5 is heated more in its upper region than in its lower region, thereby it warps due to differential thermal expansion upwards, ie in the direction of the plunger 2 to.

Since the heating is greatest here by the flow channels 10d, 10e, 10h, 10i closest to the boundary walls of the opening 6b, the machine bed 5 bends more strongly upwards in the areas adjacent to the opening 6b than in the areas of the longitudinal sides which less strongly heated by the outer flow channels 10a, 10b, 10k, 101. The platen 4, which is connected via the intermediate plate 11 shear-resistant to the machine bed 5 and is formed of a material having a greater coefficient of thermal expansion than the material of the machine bed 5, introduces additional thrust forces in the machine bed 5, which reinforce its warping upwards. As in the embodiment according to Fig. 3 In operation, under the load due to the punching force, compensation for this warping occurs, which ideally leads to the machine bed 5 being flat under maximum punching load in both the longitudinal and transverse direction, ie not warped or not bent. This solution has the advantage that existing machines with a corresponding intermediate plate 11 can be easily converted to a punching press according to the invention.

Fig. 5 shows a section through the machine base of the punching machine along the line XX in Fig. 1 , as formed according to a third embodiment of the invention. As can be seen, here the outer contours of the clamping plate 4 and the machine bed 5 are substantially identical as in the embodiment according to Fig. 2 and also the internal structure of the machine bed 5 is substantially identical to that of the machine bed Fig. 2 , However, here the machine bed 5 is penetrated in its lower region by two extending in the longitudinal direction of the machine bed tie rods 19, with which the machine bed 5 is placed in its lower region under compressive stress, for buckling of the machine bed 5 in the direction of the press ram 2. The tie rods 19 are arranged symmetrically on both sides of the opening 6b of the machine bed 5, such that they each have a smaller distance from the opening 6b than to the respective longitudinal side of the machine bed 5.

Since, by this arrangement, the tie rod 19 is placed under compressive stress most closely to the boundary walls of the aperture 6b of the machine bed 5 by the tie rods 19, the machine bed 5 buckles more upward in the areas adjacent to the aperture 6b than in Figs Areas of the long sides. The clamping plate 4, which is connected via a plurality of screws with the machine bed 5, warps together with the machine bed 5. As in the embodiments according to the FIGS. 3 and 4 In operation, under the load due to the punching force, compensation for this warping occurs, which ideally leads to the machine bed 5 being flat under maximum punching load in both the longitudinal and transverse direction, ie not warped or not bent.

As in Fig. 6 to be seen, which is a longitudinal section through the substructure Fig. 5 along the line XX in Fig. 5 shows, the tie rods 19 are each set between a nut 12 and an adjustable biasing device 13, 14, 15, 16, 17, 18 under tension. The biasing device 13, 14, 15, 16, 17, 18 comprises a clamping nut 13 with an actuating arm 16, which can be rotated by a hydraulic cylinder 15 by about 90 °, for adjusting the tension of the tie rod 19, and a discharge device with a hydraulic Piston / cylinder arrangement 14, 17, 18, by means of which the tie rod 19 can be preloaded temporarily hydraulically, to relieve the clamping nut 13 when setting the same. After adjusting the clamping nut 13, the hydraulic piston / cylinder assembly 14, 17, 18 is switched ineffective for the operation of the press.

On the underside of the machine bed 5, a strain gauge 20 is arranged below each tie rod 19, by means of which the length reduction of the machine bed 5 can be measured in this area due to the pressure voltage applied by the tie rods 19.

This third embodiment of the invention has the advantage that the setting of the warpage of the machine bed 5 is free of delay and that the deformation forces and the resulting deformations of the machine bed 5 are easily controllable.

Claims (37)

1. Method for warping the machine bed (5) of a punching press to compensate at least partially a bending caused by the punching force during punching operation, wherein the machine bed (5) has an aperture (6b) for carrying away punching parts and rubbish,
   characterised in that forces acting transverse to the punching force direction are introduced into the machine bed (5) or are created within the machine bed (5) for warping the machine bed (5) in the direction towards the press ram (2) such that the machine bed (5) is warped stronger in the area adjacent to the aperture (6b) than in the areas adjacent to the longitudinal sides.
2. Method according to claim 1, wherein the machine bed (5) with tie-rods (19) extending in its longitudinal direction is set under compressive stress in its lower area for warping the same in the direction towards the press ram (2).
3. Method according to claim 2, wherein the tie-rods (19) are arranged such that they cross the machine bed (5) in its lower area.
4. Method according to one of the claims 2 to 3, wherein on both sides of the aperture (6b) of the machine bed (5), in particular symmetrical to both sides of the aperture (6b), in each case a tie-rod (19) is arranged such that the tie-rod (19) in each case has a smaller distance to the aperture (6b) than to the respective longitudinal side of the machine bed (5).
5. Method according to one of the preceding claims, wherein a temperature gradient is produced within the machine bed (5) or a supporting structure (4, 5, 11) for the lower tool parts built with the machine bed (5), respectively, by means of which the machine bed (5) warps in the direction towards the press ram (2).
6. Method according to claim 5, wherein the temperature gradient is produced by heating the machine bed (5) in the area of its side facing the press ram (2).
7. Method according to claim 6, wherein the machine bed (5) near to the boundaries of the aperture (6b) is heated stronger than near to the longitudinal sides.
8. Method according to one of the claims 5 to 7, wherein the temperature gradient is produced by cooling the machine bed (5) in the area of its side facing away from the press ram (2).
9. Method according to claim 8, wherein the machine bed is near to the boundaries of the aperture is cooled stronger than near to the longitudinal sides.
10. Method according to one of the claims 5 to 9, wherein flow channels (10a-19f) arranged within the machine bed (5) are flown through by a heated or cooled gaseous or liquid medium (8) for producing the temperature gradient.
11. Method according to claim 10, wherein heated lubricating oil (8) of a lubricating oil circuit of the press is passed through the flow channels (10a-10f).
12. Method according to one of the claims 5 to 11, wherein electrical heating elements arranged within the machine bed are charged with electric current for producing the temperature gradient.
13. Method according to one of the claims 5 to 12, wherein a clamping plate arranged on the machine bed is present which is heated for warping the machine bed in the direction towards the press ram as a consequence of a heating of it by the clamping plate on its side facing the ram and/or for warping the machine bed in the direction towards the press ram as a consequence of an introduction of shear forces produced by a thermal expansion of the clamping plate into the side of the machine bed facing the ram.
14. Method according to one of the claims 5 to 11, wherein a clamping plate (4) arranged on the machine bed (5) is present and a heating device (11) arranged between the machine bed (5) and the clamping plate (4), which is heated for warping the machine bed (5) in the direction towards the press ram (2) as a consequence of a heating of it by the heating device (11) on its side facing the ram (2) and/or for warping the machine bed (5) in the direction towards the press ram (2) as a consequence of a heating of the clamping plate (4) by the heating device (11) and by an introduction of shear forces produced by a thermal expansion of the clamping plate (4) into the side of the machine bed (5) facing the ram (2).
15. Method according to one of the preceding claims, wherein the warp of the machine bed is adjusted depending on parameters of the punching process, in particular depending on a calculated or measured maximal punching force, and in particular, wherein the warp is adjusted during the intended operation of the press.
16. Punching press for performing the method according to claim 1, with a machine bed (5) and with a press ram (2) working against the machine bed (5),
    wherein means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) are present for warping the machine bed (5) in the direction towards the press ram (5) by an introduction of forces acting transverse to the punching force direction into the machine bed (5) and/or by producing forces acting transverse to the punching force direction within the machine bed (5),
    wherein the machine bed (5) has an aperture (6b) for carrying away punching parts and rubbish and the means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) for warping the machine bed (5) are designed such that they warp the machine bed (5) stronger in the area adjacent to the aperture (6b) than in the areas adjacent to the longitudinal sides of the machine bed (5),
    and wherein the means (12-19) for warping the machine bed comprise tie-rods (19) extending in longitudinal direction of the machine bed, by means of which the machine bed (5) can be set under compressive stress in its lower area for warping the machine bed (5) in the direction towards the press ram (2).
17. Punching press according to claim 16, wherein the tie-rods (19) cross the machine bed (5) in its lower area.
18. Punching press according to one of the claims 16 to 17, wherein on both sides of the aperture (6b) of the machine bed (5) in each case a tie-rod (19) is arranged such that in each case the tie-rod (19) has a smaller distance to the aperture (6b) than to the respective longitudinal side of the machine bed (5).
19. Punching press according to claim 18, wherein the both tie-rods (19) are arranged symmetrically to both sides of the aperture (6b).
20. Punching press for performing the method according to claim 1, with a machine bed (5) and with a press ram (2) working against the machine bed (5),
    wherein means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) are present for warping the machine bed (5) in the direction towards the press ram (5) by introducing forces acting transverse to the punching force direction into the machine bed (5) and/or by producing forces acting transverse to the punching force direction within the machine bed (5),
    wherein the machine bed (5) has an aperture (6b) for carrying away punching parts and rubbish and the means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) for warping the machine bed (5) are designed such that they warp the machine bed (5) in the area adjacent to the aperture (6b) stronger than in the areas adjacent to the longitudinal sides of the machine bed (5),
    wherein the means (8, 9a, 9c, 10a-10f; 10a-10l, 11) for warping the machine bed (5) are designed for producing a temperature gradient within the machine bed (5) or a supporting structure (4, 5; 4, 5, 11) for the lower tool parts built with the machine bed (5), respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram,
    wherein the means (8, 9a, 9c, 10a-10f) for warping the machine bed (5) comprise flow channels (10a-10f) arranged within the machine bed (5), which can be flown through by a heated or cooled gaseous or liquid medium (8) during the intended operation of the press for producing the temperature gradient
    and wherein the press comprises a lubricating oil circuit and the means for warping the machine bed comprise arrangements, by means of which heated lubricating oil of the lubricating oil circuit can be passed through the flow channels (10a-10f) during the intended operation of the press.
21. Punching press according to claim 20, wherein the means (8, 9a, 9c, 10a-10f; 10a-10l, 11) for warping the machine bed (5) are designed for heating the machine bed (5) in the area of its side facing the press ram (2).
22. Punching press according to claim 21, wherein the means (8, 9a, 9c, 10a-10f; 10a-10l, 11) for warping the machine bed (5) are designed to heat the machine bed (5) in the area of its side facing the press ram (2) stronger near to the boundaries of the aperture (6b) than near to its longitudinal sides.
23. Punching press according to one of the claims 20 to 22, wherein the means for warping the machine bed are designed to cool the machine bed in the area of its side facing away from the press ram.
24. Punching press according to claim 23, wherein the means for warping the machine bed are designed to cool the machine bed in the area of its side facing away from the press ram stronger near to the boundaries of the aperture than near to its longitudinal sides.
25. Punching press according to one of the claim 20 to 24, wherein the means for warping the machine bed comprise electrical heating elements arranged within the machine bed, which can be charged by electric current during the intended operation of the press for producing the temperature gradient.
26. Punching press according to one of the claims 20 to 25, wherein on both sides of the aperture of the machine bed in each case one or more flow channels and/or electrical heating elements are arranged within the machine bed such that, per side, the sum of the distances of the flow channels and/or the heating elements to the aperture is smaller than the sum of the distances of the flow channels and/or heating elements to the respective longitudinal sides of the machine bed.
27. Punching press according to claim 26, wherein the flow channels and/or the heating elements are arranged symmetrically to both sides of the aperture.
28. Punching press for performing the method according to claim 1, with a machine bed (5) and with a press ram (2) working against the machine bed (5),
    wherein means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) are present for warping the machine bed (5) in the direction towards the press ram (5) by introducing forces acting transverse to the punching force direction into the machine bed (5) and/or by producing forces acting transverse to the punching force direction within the machine bed (5),
    wherein the machine bed (5) has an aperture (6b) for carrying away punching parts and rubbish and the means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) for warping the machine bed (5) are designed such that they warp the machine bed (5) in the area adjacent to the aperture (6b) stronger than in the areas adjacent to the longitudinal sides of the machine bed (5),
    wherein the means (8, 9a, 9c, 10a-10f; 10a-10l, 11) for warping the machine bed (5) are designed for the production of a temperature gradient within the machine bed (5) or a supporting structure (4, 5; 4, 5, 11) for the lower tool parts built with the machine bed (5), respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram,
    and wherein a clamping plate arranged on the machine bed is present which can be heated by the means for warping the machine bed during the intended operation of the press for producing the temperature gradient by heating the machine bed on its side facing the ram by the clamping plate.
29. Punching press for performing the method according to claim 1, with a machine bed (5) and with a press ram (2) working against the machine bed (5),
    wherein means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) are present for warping the machine bed (5) in the direction towards the press ram (5) by introducing forces acting transverse to the punching force direction into the machine bed (5) and/or by producing forces acting transverse to the punching force direction within the machine bed (5),
    wherein the machine bed (5) has an aperture (6b) for carrying away punching parts and rubbish and the means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) for warping the machine bed (5) are designed such that they warp the machine bed (5) in the area adjacent to the aperture (6b) stronger than in the areas adjacent to the longitudinal sides of the machine bed (5),
    wherein the means (8, 9a, 9c, 10a-10f; 10a-10l, 11) for warping the machine bed (5) are designed for the production of a temperature gradient within the machine bed (5) or a supporting structure (4, 5; 4, 5, 11) for the lower tool parts built with the machine bed (5), respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram,
    and wherein a clamping plate (4) arranged on the machine bed (5) is present which can be heated by the means (8, 9a, 9c, 10a-10f; 10a-10l, 11) for warping the machine bed (5) during the intended operation of the press and which is connected with the machine bed (5) such that it can transfer shear forces to the machine bed (5) for warping the machine bed (5) in the direction towards the press ram (2) as a consequence of an introduction of shear forces produced by a thermal expansion of the clamping plate (4) into the side of the machine bed facing the press ram (2).
30. Punching press according to claim 29, wherein a thermal insulation layer is present between the clamping plate and the machine bed for reducing a heat transfer from the clamping plate to the machine bed.
31. Punching press according to claim 30, wherein the thermal insulation layer is present in the areas, which adjoin the longitudinal sides of the clamping plate or of the machine bed, respectively, between the clamping plate and the machine bed and in the areas, which adjoin the aperture, a layer between the clamping plate and the machine bed is present which has an essentially better thermal conductivity for promoting a heat transfer from the clamping plate to the machine bed in these areas.
32. Punching press according to one of the claims 28 to 31, wherein the clamping plate can be heated by the means for warping the machine bed during the intended operation of the press such that it is warmer in the areas which adjoin the aperture than in the areas which adjoin the longitudinal sides.
33. Punching press for performing the method according to claim 1, with a machine bed (5) and with a press ram (2) working against the machine bed (5),
    wherein means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) are present for warping the machine bed (5) in the direction towards the press ram (5) by introducing forces acting transverse to the punching force direction into the machine bed (5) and/or by producing forces acting transverse to the punching force direction within the machine bed (5),
    wherein the machine bed (5) has an aperture (6b) for carrying away punching parts and rubbish and the means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) for warping the machine bed (5) are designed such that they warp the machine bed (5) in the area adjacent to the aperture (6b) stronger than in the areas adjacent to the longitudinal sides of the machine bed (5),
    wherein the means (8, 9a, 9c, 10a-10f; 10a-10l, 11) for warping the machine bed (5) are designed for the production of a temperature gradient within the machine bed (5) or a supporting structure (4, 5; 4, 5, 11) for the lower tool parts built with the machine bed (5), respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram,
    and wherein a clamping plate (4) arranged on the machine bed (5) is present and wherein the means (10a-10l, 11) for warping the machine bed (5) comprise a heating device (11) arranged between the machine bed (5) and the clamping plate (4), which can be operated during the intended operation of the press for warping the machine bed (5) as a consequence of a heating of it on its side facing the ram (2).
34. Punching press for performing the method according to claim 1, with a machine bed (5) and with a press ram (2) working against the machine bed (5),
    wherein means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) are present for warping the machine bed (5) in the direction towards the press ram (5) by introducing forces acting transverse to the punching force direction into the machine bed (5) and/or by producing forces acting transverse to the punching force direction within the machine bed (5),
    wherein the machine bed (5) has an aperture (6b) for carrying away punching parts and rubbish and the means (8, 9a, 9c, 10a-10f; 10a-10l, 11; 12-19) for warping the machine bed (5) are designed such that they warp the machine bed (5) in the area adjacent to the aperture (6b) stronger than in the areas adjacent to the longitudinal sides of the machine bed (5),
    wherein the means (8, 9a, 9c, 10a-10f; 10a-101, 11) for warping the machine bed (5) are designed for the production of a temperature gradient within the machine bed (5) or a supporting structure (4, 5; 4, 5, 11) for the lower tool parts built with the machine bed (5), respectively, in order to produce the forces acting transverse to the punching force direction for warping the machine bed in the direction towards the press ram, and
    wherein a clamping plate (4) arranged on the machine bed (5) is present, which is connected with the machine bed (5) such that it can transfer shear forces to the machine bed (5), and wherein the means (10a-10l, 11) for warping the machine bed (5) comprise a heating device (11) arranged between the machine bed (5) and the clamping plate (4), which can be operated during the intended operation of the press for warping the machine bed (5) in the direction towards the press ram (2) as a consequence of an introduction of shear forces produced by a thermal expansion of the clamping plate (4) into the side of the machine bed (5) facing the ram (2).
35. Punching press according to one of the claims 33 to 34, wherein the heating device (11) arranged between the machine bed (5) and the clamping plate (4) is designed such that with it the areas of the machine bed (5) or of the clamping plate (4), respectively, which adjoin the aperture (6b) can be heated stronger than the areas of the machine bed (5) or of the clamping plate (4), respectively, which adjoin their longitudinal sides.
36. Punching press according to one of the claims 16 to 35, wherein the means for warping the machine bed are built adjustable, in particular during the intended operation of the press, for enabling a specific adjustment of the warp of the machine bed.
37. Punching press according to one of the claims 16 to 36, wherein the punching press comprises a press control, by means of which the warp of the machine bed, in particular automatically, is adjustable depending on parameters of the punching process, in particular depending on a calculated or measured maximal punching force, and in particular is adjustable during the intended operation of the press.

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