EP2809505B1 - Bending press with c-shaped frame - Google Patents

Description

The invention relates to a press with a C-shaped frame, comprising a first linear motor facing away from a pressing point at a central portion of the C-shaped frame.

Presses are common in modern manufacturing processes. For example, presses are used for joining (e.g., press-fitting bushings), severing (e.g., cutting sheet metal strips), master forming (e.g., pressing powders into bodies), and forming (e.g., bending or deep-drawing sheets). Even these few examples show how versatile presses are used in technology. In principle, a distinction can be made between presses with an open or C-shaped frame and presses with a closed or O-shaped frame. The invention now relates to presses with C-shaped frames in which the asymmetric structure without additional measures leads to a springing of the frame as soon as a force is applied to the pressing site. This springing now leads to the fact that the feed of the press ram, which is determined for example on the drive, not actually acts at the pressing point. In addition, there is an angular offset and a lateral offset between the punch and die. All these factors mean that the press result is qualitatively unsatisfactory and difficult to reproduce.

From the prior art, some presses are known in which this springing is reduced or prevented. For example, the US 2,580,078 A1 For this purpose, a hydraulic press with a C-shaped frame, in which a pressure point facing away from the hydraulic cylinder generates a counter force and thus reduces springing or bending of the frame.

Furthermore, from the DE 1906223 A1 a press with a C-shaped frame known, in which a bending of the frame is compensated under load by a pressure cylinder remote from the hydraulic cylinder.

In addition, the shows JP 02-274400 A2 a press with a C-shaped frame, in which a springing of the frame by two L-shaped arranged on the frame hydraulic cylinder to be compensated.

The DE 30 27 495 A1 discloses another example in which a springing of a frame by a hydraulic cylinder facing away from a pressing point to be counteracted.

The US 5,097,734 shows finally a last example of a press, in which a springing up of a C-shaped frame by means of counterbalancing cylinders is counteracted. The force of the compensating cylinder is introduced via a linkage in the frame.

The DE 102007020166 A1 discloses a press according to the preamble of claim 1.

In particular, at the rear of the C-shaped frame mounted pressure cylinders, a considerable tensile force is exerted on the central part of the frame, which can make up twice the actual pressing force and more depending on the leverage of the compensating cylinder. The middle part must therefore be dimensioned correspondingly stronger than conventional presses.

The object of the invention is therefore to provide an improved press, in particular one in which a force is reduced to the central part of the C-shaped frame.

The object of the invention is achieved with a press according to claim 1, namely a press of the type mentioned above, additionally comprising a pressing point facing, the second linear motor at the central portion, wherein the linear motors are provided for a counteracting drive, such that a springing the C-shaped frame is counteracted. The linear motors act in each case between two mutually distanced fastening points on the central portion of the frame, ie one adjacent to the pressing point front of the central frame portion and the other at the side remote from the pressing point back of the central frame portion.

According to the invention is achieved in that the middle part of the C-shaped frame is relieved by the other linear motor. For this reason, the frame can now be made smaller which results in lower material usage and therefore lower weight.

Advantageous embodiments and modifications of the invention will become apparent from the dependent claims and from the description in conjunction with the figures of the drawing.

It is advantageous if the middle section of the C-shaped frame has a constriction in the case of the linear motors. In this way, the effect of the linear motors can be increased, since the frame does not oppose the compensation forces of the linear motors so much resistance.

It is favorable if the forces generated by the facing / facing away from the linear motor are different in magnitude. In this way, a further relief of the central portion of the C-shaped frame can be achieved.

It is also advantageous if the press comprises a sensor for detecting a springing of the C-shaped frame and an associated control, which is prepared for driving the linear motor, so that a springing of the C-shaped frame is counteracted. In this way, a deformation of the frame can be fully compensated. The control also ensures that the force compensation is performed correctly under a variety of conditions and influences.

It is advantageous if the sensor comprises a photosensitive position detection element which is arranged on one leg of the C-frame and a laser light source which is arranged on the other leg of the C-shaped frame, wherein the laser light source for illuminating the position detection element is provided This is a comparatively simple and yet secure method for determining the deformation of a C-shaped frame. Since the laser is fixedly connected to a leg of the frame, deformation thereof automatically results in deflection of the laser beam which can be easily detached some distance away from the photosensitive position detecting element as the distance traveled by a light spot.

It is advantageous if hydraulic cylinders are provided as linear motors. Hydraulic cylinders are particularly suitable for applying high forces. In addition, a hydraulic system already exists in many presses anyway, so that these presses can be easily equipped or retrofitted with the inventive device.

Finally, it is advantageous if a connecting line is provided between the hydraulic cylinders, such that a pressure is generated by the pressing process in the facing / averted hydraulic cylinder, which pressure is conducted to the facing / facing hydraulic cylinder. In this way, can be dispensed with a pump which pressurizes the hydraulic oil, that is, the system works passively. This system is therefore particularly well suited for retrofitting presses that do not have their own hydraulic system.

Nevertheless, if the suspension of the frame of the press in the vertical Y-axis direction can not be fully compensated, it is advantageous if the linear motors are driven so that the tip of the punch in a pressing operation with respect to a horizontal X-axis direction in a vertical plane through the center of the die or when the linear motors are controlled so that the orientation of the punch during a pressing parallel to the alignment of the die, ie in the vertical direction, depending on which variant the better bending results can be achieved.

The above embodiments and further developments of the invention can be combined in any manner.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Fig. 1

eine schematisch dargestellte Presse mit einem C-förmigen Rahmen in Schrägansicht;

Fig. 2

das Auffedern des C-förmigen Rahmens;

Fig. 3

eine erste Variante einer Presse mit zwei gegenüberliegenden Hydraulikzylindern zur Verminderung des Auffederns;

Fig. 4

eine dem Verständnis dienende, nicht erfindungsgemäße Variante einer Presse mit aufgetrenntern Rahmen;

Fig. 5

die Kräfteverhältnisse bei einer Presse nach Fig. 3;

Fig. 6

die Kräfteverhältnisse bei einer Presse nach Fig. 4;

Fig. 7

eine schematisch dargestellte Regelung der Hydraulikzylinder der erfindungsgemäßen Presse.

Each shows in a highly schematically simplified representation:

Fig. 1

a schematically illustrated press with a C-shaped frame in an oblique view;

Fig. 2

the springing up of the C-shaped frame;

Fig. 3

a first variant of a press with two opposite hydraulic cylinders to reduce the springing;

Fig. 4

an understanding, not inventive variant of a press with a separate frame;

Fig. 5

the balance of power in a press after Fig. 3 ;

Fig. 6

the balance of power in a press after Fig. 4 ;

Fig. 7

a schematically illustrated control of the hydraulic cylinder of the press according to the invention.

By way of introduction, it is stated that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component designations, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals and component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position. Furthermore, individual features or combinations of features from the illustrated and described different exemplary embodiments may also represent separate, inventive or inventive solutions.

The embodiments show possible Ausflihrungsvarianten a press according to the invention, it being noted at this point that the invention is not limited to the Ausfüihrungsvarianten specifically illustrated, but rather also various combi nations of the individual embodiments are mutually possible and this variation possibility due to the teaching of technical action by objective invention in the skill of those working in this technical field is the expert. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiment variant, includes the scope of protection.

Fig. 1 shows a schematically illustrated press 1 with a C-shaped frame 2 in an oblique view, wherein the frame 2 comprises a central portion 2a and two legs 2b, 2c. The press shown consists of two frame members 2 which are connected by an upper crossbar 3, to which a punch 4 is attached, and a lower crossbar 5, to which a die 6 is attached. In this example, the upper crossbar 3 by means of a drive, not shown (eg hydraulic cylinder, spindle drive, etc.) can be moved vertically in a conventional manner, in this way, punch 4 and die 6 from the rest position shown in a pressing position against each other , However, this arrangement is not absolutely necessary for the invention, but rather it is also conceivable that the lower pressing bar 5 or both pressing bars 3 and 5 are displaceable.

Fig. 2 now shows the springing of the C-shaped frame 2 when a pressing force between the punch 4 and die 6 is generated. In particular, the middle section 2a and the upper leg 2b are deformed (it is assumed that the lower leg 2c is firmly anchored in the ground). In the Fig. 2 Of course, the proportions of better representability are greatly exaggerated. In a real press 1, the deformations are usually much lower. By a photosensitive position detection element 7, which is arranged on the bottom or on the lower leg 2c of the frame 2 and which is irradiated by a laser light source 8, which is attached to the upper leg 2b, the deformation of the frame 2 can be measured. It is clearly visible how the deformation of the frame 2 leads to a change of the laser beam a, which can be measured as a length at the position detection element 7. The position detection element 7 can be constructed, for example, from a plurality of juxtaposed photosensitive cells. But other designs are equally applicable.

This springing now leads to the fact that the feed of the punch 4, which is determined at the drive (for example, by position sensors on the associated hydraulic cylinders) does not actually act at the press point between the punch 4 and die 6. In addition, there is an angular offset and a lateral offset between the punch 4 and die 6. All these factors cause the bending result on the one hand, qualitatively unsatisfactory and also difficult to reproduce.

Fig. 3 now shows a first variant of a press 1 ', in which a first linear motor 9, which faces away from the pressing point, and a second linear motor 10, which faces the pressing point, counteracts the springing of the frame 2. The first linear motor 9 acts between two attachment points on the rear side of the middle frame section 2a and the second linear motor 10 acts between two attachment points on the front side of the middle frame section 2a. In this and the following examples are provided as linear motors 9 and 10 hydraulic cylinder. However, this is not to be understood as limiting the invention, because in principle other types of linear motors are also suitable, in particular spindle drives.

The first hydraulic cylinder 9 is now subjected to a first pressure p ₁ , which leads to a pressure force between the attachment points of the first hydraulic cylinder 9 and to an increase in the distance between them. Similarly, the second hydraulic cylinder 10 is acted upon by a second pressure p ₂ , which leads to a tensile force between the attachment points of the second hydraulic cylinder 10 and a shortening of the distance between them. In an advantageous variant, the middle section 2a in the region of the hydraulic cylinders 9 and 10 has an indentation b in order to increase the action of the hydraulic cylinders 9 and 10. The pressures p ₁ and p ₂ can be actively set up by a hydraulic pump. It is also conceivable that the two hydraulic cylinders 9 and 10 are connected by a line. The system is passive.

Fig. 4 shows a press 1 "not falling within the scope of the patent, similar to that in Fig. 3 shown press 1 '. The frame 2 is completely separated in the area of the hydraulic cylinders 9 and 10. The forces between the upper and lower part of the central portion 2a of the frame 2 are thus transmitted only by the hydraulic cylinders 9 and 10. To avoid misalignment of the two parts a mounted in the lower part bar 11 is mounted between two guides 12 arranged on the upper part. The "classic" drive of a press 1 ", namely the linear motors for moving the upper crossbar 3, can therefore be dispensed with in principle and instead be taken over by the hydraulic cylinders 9 and 10. If the press 1" has a suitable control (see also FIG Fig. 7 ), the guide 12 can also be made relatively delicate, since ideally all moments are compensated and only forces act in the vertical direction.

Fig. 5 now shows the balance of power on a press 1 'as in Fig. 3 shown. At the pressing point, the pressing force F _P acts. On the frame 2, the opposite frame force F _R acts. In this example, pressing force F _P and frame force F _R are equal in magnitude. The forces F ₁ and F _{2 of} the hydraulic cylinders 9 and 10 thus serve only the moment equals. In terms of magnitude, these forces F ₁ and F ₂ are comparatively large because of the short lever. It is also conceivable, of course, for the hydraulic cylinders 9 and 10 to take over part of the frame force F _R. F ₂ then becomes larger in size, F ₁ smaller in amount.

Fig. 6 shows the balance of power on a press 1 "as in Fig. 4 represented and thus an extreme case of said assumption of the frame force F _R , which is completely eliminated in this example.

At this point it is noted that different high forces of the hydraulic cylinders 9 and 10 can be realized by different high pressures p ₁ , p ₂ and / or different piston surfaces. In particular, in passive systems but also the geometric conditions are taken into account. Since the pressure p ₁ and p ₂ in both hydraulic cylinders 9 and 10 because of the connecting line is the same size, different power ratios can only be realized by different sized piston surfaces. But because the displaced liquid volume in both hydraulic cylinders 9 and 10 is the same size, then put both pistons different ways back. This is to be considered in a design of the press 1 'or 1 "accordingly.

Fig. 7 now shows an arrangement in which the two hydraulic cylinders 9 and 10 (not shown here) are regulated. For this purpose, a hydraulic pump 14 is provided, which hydraulic oil from a reservoir 13 via valves 15 and 16 to the two hydraulic cylinders. 9 and 10 pumps. It is assumed that the first valve 15 controls the first pressure p1 for the first hydraulic cylinder 9 and the second valve 16 controls the second pressure p2 for the second hydraulic cylinder 10. A sensor (in the example shown this is the photosensitive position detection element 7 off Fig. 2 , which is illuminated by a laser light source 8) transmits the angular offset between punch 4 and die 6 (that is, here a length derived from the angular offset) to a controller 17. The controller 17 determines from this signal control signals for the valves 15 and 16. Die Hydraulic cylinders 9 and 10 can be controlled in this way so that an offset between the punch 4 and die 6 is completely compensated. This is especially in a press 1 "after Fig. 4 advantageous since between beam 11 and the guides 12 then no more moment is transmitted.

The control 17 can be constructed in principle from any commercially available controller. However, it is particularly advantageous if the controller 17 is constructed from a central processing unit with a memory connected thereto. In the memory then necessary for program execution steps and parameters are stored and retrieved at runtime from the central processing unit. Especially with a press 1 "after Fig. 4 this is advantageous since the control 17 can then also control the vertical displacement of the upper crossbar 3.

If the rebound of the frame 2 of the press 1 in the vertical Y-axis direction can not be completely compensated, it is nevertheless advantageous if the linear motors 9, 10 are controlled such that the tip of the punch 4 is pressed in a pressing operation relative to a horizontal X axis. Axial direction in a vertical plane through the center of the die 6 or the linear motors 9, 10 are driven so that the orientation of the punch 4 in a pressing operation parallel to the alignment of the die 6.

For the sake of order, it should finally be pointed out that, for a better understanding of the construction of the arrangement according to the invention, these or their components have been shown partially unevenly and / or enlarged and / or reduced in size.

Finally, it is noted that - although always a bending press is shown in the figures - the invention by no means exclusively on a bending press or a bending press of the type shown. Rather, the invention also relates to other presses, for example stamping presses, deep drawing presses, forging presses, embossing presses, etc. Furthermore, the invention is independent of the nature of the drive of the press and therefore equally relates to eccentric presses, toggle presses, crank presses, screw presses, hydraulic presses Finally, the application of the principle according to the invention is not limited to presses in which a compressive force acts between the two legs of the C-shaped frame, but can also be extended to cases in which a tensile force acts at this point. The statements made to the figures are then to reverse accordingly.

The task underlying the independent inventive solutions can be taken from the description.

Above all, the individual in the Fig. 1 to 7 shown embodiments form the subject of independent solutions according to the invention. The relevant objects and solutions according to the invention can be found in the detailed descriptions of these figures.

REFERENCE NUMBERS

1, 1 ', 1 "

Press

2

frame

2a

middle section of the frame

2b, 2c

Legs of the frame

3

upper crossbeam

4

stamp

5

lower crossbeam

6

die

7

Position sensing element

8th

Laser light source

9

first hydraulic cylinder

10

second hydraulic cylinder

11

guide beams

12

guide rail

13

oilcontainer

14

hydraulic pump

15

first valve

16

second valve

17

regulation

a

laser beam

b

constriction

F ₁

Force first hydraulic cylinder

F ₂

Force second hydraulic cylinder

F _P

pressing force

F _R

frame power

p ₁

Pressure of the first hydraulic cylinder

P ₂

Pressure second hydraulic cylinder

Claims (9)

1. A bending press (1) with a C-shaped frame (2) comprising a central section (2a) and two legs (2b, 2c), with a first linear motor (9) on the central section (2a), wherein the first linear motor (9) faces away from a pressing point and acts upon the section (2a) between two fastening points that are spaced apart from one another and from the legs (2b, 2c), characterized by a second linear motor (10) on the central section (2a), wherein the second linear motor faces the pressing point and acts upon the section (2a) between two fastening points that are spaced apart from one another and from the legs (2b, 2c), and wherein the linear motors (9, 10) are designed for a diametrically opposed actuation such that a frame stretch of the C-shaped frame (2) is counteracted.
2. The bending press (1) according to claim 1, characterized in that the central section (2a) of the C-shaped frame (2) features a constriction (b) at the linear motors (9, 10).
3. The bending press (1) according to claim 1 or 2, characterized in that the forces (F₁, F₂) generated by the facing linear motor/the linear motor facing away (9, 10) differ with respect to their magnitude.
4. The bending press (1) according to one of claims 1 to 3, characterized by a sensor for detecting a frame stretch of the C-shaped frame (2), as well as a control (17) that is connected to said sensor and prepared for actuating the linear motors (9, 10) in such a way that a frame stretch of the C-shaped frame (2) is counteracted.
5. The bending press (1) according to claim 4, characterized in that the sensor is realized in the form of a light-sensitive position detection element (7) that is arranged on one leg (2c) of the C-shaped frame (2) and a laser light source (8) that is arranged on the other leg (2c) of the C-shaped frame (2), wherein the laser light source (8) is designed for illuminating the position detection element (7).
6. The bending press (1) according to one of claims 1 to 5, characterized in that hydraulic cylinders are provided as linear motors (9, 10).
7. The bending press (1) according to claim 6, characterized in that a connecting line is provided between the hydraulic cylinders (9, 10) such that a pressure generated in the facing hydraulic cylinder/the hydraulic cylinder facing away (9, 10) due to the pressing operation is transmitted to the facing hydraulic cylinder/the hydraulic cylinder facing away (10, 9).
8. The bending press (1) according to one of claims 1 to 7, characterized in that the linear motors (9, 10) are actuated in such a way that the point of the punch (4) lies in a vertical plane through the center of the die (6) during a pressing operation referred to the direction of a horizontal X-axis.
9. The bending press (1) according to one of claims 1 to 7, characterized in that the linear motors (9, 10) are actuated in such a way that the alignment of the punch (4) extends parallel to the alignment of the die (6) during a pressing operation.

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