The invention relates to a drawing press, which serves to produce molded sheet metal parts, such as auto body parts, for example.
Double-acting presses are known for deep-drawing sheet metal parts. In the case of such presses, a sheet metal holding ring is arranged so as to be capable of being moved relative to a drawing punch. The sheet metal holding ring bears on the circuit board, which is to be deformed, and exerts a holding force of clamping force, while the drawing punch subsequently deforms the circuit board in cooperation with a mold. Such a press is known from DE 24 19 389, for example. Provision is made therein for a hydraulic drawing press, in the case of which a drawing punch as well as a sheet metal holding ring 12 are provided on a ram, which can be moved in working direction. In response to the downwards movement of the ram, the sheet metal holding ring thus initially impacts the circuit board and a deformation of the circuit board by means of the drawing punch takes place only in response to a continued downwards movement.
A double-acting molding machine comprising an inner ram and an outer ram is further known from DE 199 43 441 A1. An eccentric drive encompasses an eccentric shaft, which is connected to the outer ram via connecting rods. A toggle joint drive having two joint levers connects the inner ram to the eccentric shaft via a further lever.
Based on the known presses, it can be considered to be a task of the instant invention to design the possible applications of the press to be more flexible and to ensure a high quality of the produced molded parts.
For this purpose, the drawing press encompasses a first ram, which can be driven in a working direction by means of a first ram drive. The drawing press furthermore has a second ram, which can be driven by means of a second ram drive. The two ram drives in each case encompass an electric motor. Both ram drives can be activated independent from one another, so that the movements of the first ram and of the second ram relative to the lower die or to the circuit board, respectively, can be carried out and provided independently. A control unit serves to drive the ram drives. The drawing press furthermore encompasses a coupling means, which can be switched between a coupling state and an uncoupling state. In the coupling state, a kinematic coupling is established between the two rams, which prevents a relative movement of the first ram relative to the second ram. Preferably, the coupling means is a mechanical coupling means, which establishes a direct mechanical connection between the two rams in the case of one exemplary embodiment, and which effects a kinematic coupling of the two ram drives in the case of another exemplary embodiment. The drawing press can therefore be switched between a single-acting mode of operation in the coupling state and a double-acting mode of operation in the uncoupling state via the coupling means.
In the uncoupling state, the second ram can be used as a holding-down device, for example. Its position, its movement speed and/or its clamping force, with which it holds the circuit board, can be provided freely and independent from the position and/or the speed, at which the first ram moves, which can serve as drawing punch, for example. The sheet metal holding force, which is exerted by the second ram in the case of this mode of operation and its course during the drawing process are significant for the quality of the produced molded part. Due to the independence of the two ram movements, the sheet metal holding force, which the second ram exerts on the circuit board, can be adapted to the requirements of the drawing process, such as, e.g., the material and the thickness of the circuit board. In addition, it is possible to adjust this sheet metal holding force completely independently from the current position of the drawing punch, which is formed by the first ram. The sheet metal holding force can be adjusted to the speed of the first drawing punch, for example, in this manner. Independent on the movement control of the first drawing punch, the possibility further arises to provide a switching between a position-controlled or position-regulated and a force-controlled or force-regulated control of the second ram drive via the control unit.
In the event that the coupling state is established via the coupling means, the two rams move together in working direction. It is thus possible to press the two rams against the circuit board using a high molding force. The forces, which are provided by the first ram drive and by the second ram drive in working direction, can be added to form a high total force in the coupling state. As a function of the concrete processing task, it can also be sufficient in the coupling state, if only one of the ram drives is moved. In the coupling state, the two rams preferably form a common enlarged clamping surface. In the coupling state, the drawing press interacts as a single-acting press with a drawing tool, which is attached to the press frame in this operating mode.
It is advantageous, if the two ram drives are kinematically identical. They can be embodied as eccentric drives or joint drives, for example. Due to the identical embodiment of the two ram drives, it is attained that the same control of both ram drives can take place very simply in the case of the coupling by means of the control unit, when the drawing force, which is required for the drawing process, is larger than the force, which can be exerted by an individual ram drive. A complex control with different parameters for each ram drive is avoided in this case.
The coupling means can establish a kinematic connection between the two ram drives, for example. In this case, said coupling means can be embodied as switchable shaft coupling or as intermediate drive between the two ram drives. The coupling means is controlled in particular by means of the control unit, so as to switch between the coupling state and the uncoupling state. The operating state of the drawing press can be changed particularly quickly and easily in this manner.
The electric motors of the ram drives can be embodied as servomotors or as torquemotors. They make it possible to accurately adjust the position and/or force of the rams in working direction. In a manner of speaking, the ram drives are “dry” and do not require any hydraulic liquid. In the case of the preferred exemplary embodiment of the drawing press, the two ram drives are embodied as top drives and are therefore arranged above the two rams on the press frame. The lower die, which is located opposite the rams in working direction, can be embodied so as to be completely free of drives.
Advantageous embodiments of the drawing press according to the invention follow from the dependent patent claims as well as from the description. The description is limited to significant features of the invention. The drawing should be used as a supplement.
Other objects and advantages of the present invention will become apparent to those skilled in the art upon a review of the following detailed description of the preferred embodiments and the accompanying drawings.
A first ram 17 as well as a second ram 18 are arranged on the press frame 11 in a working direction A and so as to be movable substantially vertically, for example. In the exemplary embodiment described herein, the first ram 17 is embodied as an inner ram, which is surrounded by the second ram 18 in a ring-shaped manner. The two rams 17, 18 are arranged coaxially to one another. An upper tool element 19, for example. which cooperates with a lower tool element 20 of a bottom die 21, to mold a circuit board 22, is arranged on the first ram 17.
A first ram drive 25 is present for driving the first ram 17. The first ram drive 25 encompasses a first electric motor 26, for example a servomotor or a torquemotor, which drives a first eccentric shaft 27. At least one eccentric 28 and two eccentrics 28, for example, on which a connecting rod 29 is in each case rotatably supported, is arranged on the first eccentric shaft. On the opposite side of the eccentric 28, each connecting rod 29 is connected to the first ram 17 in an articulated manner. In response to a rotation of the eccentric shaft 27, the connecting rods 29 are displaced in working direction A, which can bring about the upwards and downwards movement of the first ram 17 in working direction A.
A second ram drive 30 having a second electric motor 31 serves to drive the second ram 18. The two ram drives are designed so as to be kinematically identical. The second electric motor 31 therefore drives a second eccentric shaft 32, on which at least one and for example two eccentrics 28 are arranged in a torque proof manner. Analogously to the first eccentric drive 25, two connecting rods 29, which are connected to the second ram 28 in an articulated manner, are rotatably supported on these eccentrics 28. The two ram drives 25, 30 are designed so as to be kinematically identical. They encompass the same electric motors 26, 31 and the same translations, so that the same movement of the respective assigned ram 17, 18 is effected in working direction A in response to the control of the ram drives 25, 30 with the same control variable. The connecting rods 29 of the ram drives 25, 30 have the same length. Substantially the same forces of the rams 17 or 18, respectively, also result in working direction A in the case of the same control variable of the two ram drives 25, 30.
The two ram drives 25, 30 are controlled by means of a control unit 33. The control unit 33 can adjust and provide the movement and/or position and/or force of each ram 17, 18 independently. The first ram 17 and/or the second ram 18 can be position-controlled or position-regulated or force-controlled or force-regulated, for example, in this manner. The corresponding control of the ram drive 25, 30 or of the respective electric motor 26, 31, respectively, takes place by means of the control unit 33.
A coupling means 35 will furthermore be switched between a coupling state and an uncoupling state via the control unit 33. In the uncoupling state, the two rams 17, 18 can move completely independent from one another in working direction A. In the coupling state, the coupling means 35 prevents a relative movement between the two rams 17, 18 in working direction A. In the latter case, the two rams 17, 18 move only together.
In the case of the exemplary embodiments described herein, the coupling means 35 establishes a mechanical and/or kinematic coupling between the two rams 17, 18. In the case of a first exemplary embodiment according to
The drawing press 10 can either be operated as double-acting press or a single-acting press as a function of the state of the coupling means 35. For the operation as a single-acting press, the lower die 21 encompasses a drawing device 40 (
The upper tool element 19 and the lower tool element 20 are embodied so as to complementary to one another. It is possible to embody the lower tool element 20 or the upper tool element 19 as a shape having a concave recess, as is shown in an exemplary manner in
The drawing press 10 operates as follows:
With reference to
The control unit controls the second ram drive 30 independent from the first ram drive 25 such that it only reaches the circuit board 22 when the first ram 18 acts on the circuit board 22 with the desired clamping force. The actual drawing process of the circuit board 22 is carried out via the control or regulation of the position and/or of the speed of the first ram 17 in working direction A. For this purpose, the upper tool element 19 and the lower tool element 20 cooperate and bring the circuit board 22 into the desired shape. During this molding process, the clamping force, which the second ram 18 exerts onto the circuit bard 22, can vary. The clamping force can be adjusted so as to be adapted to the position and/or the speed of the first ram 17. Due to the independence of the two ram drives 25, 30 and due to the fact that the ram drives 25, 30 are embodied as electric drives, a corresponding control by the control unit 33 is possible very simply and accurately.
The drawing press 10 can also be operated as single-acting press, as it is illustrated in
In the case of the exemplary embodiments described herein, the two ram drives 25, 30 are embodied as top drives. According to the embodiment according to
Instead of the eccentric drives 25, 30, a joint drive 51 can also be used as ram drive. A joint drive 51 encompasses two levers 52, which are connected to one another in an articulated manner, wherein the one lever 52 is connected in an articulated manner to the assigned ram 17 or 18, respectively, and the respective other lever 52 is connected in an articulated manner to the press frame 11. A drive lever 53, which is driven by means of an eccentric 54, is located at the joint connection between the two levers 52.
The invention relates to a drawing press 10 having a first ram 17 and a second ram 18. The first ram 17 is moved by means of an electromotive first ram drive 25 and the second ram 18 is moved by means of an electromotive second ram drive in a working direction A. The drawing press 10 further encompasses a coupling means 35, which can be switched between an uncoupling state and a coupling state. In the uncoupling state, the two rams 17, 18 can move independent from one another in working direction A. In the coupling state, the coupling means 35 ensures that a relative movement is prevented between the two rams 17, 18. The drawing press 10 can thus be operated as a single-acting or double-acting press.
The above detailed description of the present invention is given for explanatory purposes. It will be apparent to those skilled in the art that numerous changes and modifications can be made without departing from the scope of the invention. Accordingly, the whole of the foregoing description is to be construed in an illustrative and not a limitative sense, the scope of the invention being defined solely by the appended claims.
Number | Date | Country | Kind |
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102011001314.8 | Mar 2011 | DE | national |
The present patent application is based upon and claims the benefit of German patent application no. 102011 001 314.8 filed Mar. 16, 2011 and PCT application no. PCT/EP2012/054716, filed Mar. 16, 2012.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2012/054716 | 3/16/2012 | WO | 00 | 10/14/2013 |