EP2554363B1 - Electric drive for a press - Google Patents

Description

The invention is in the field of forming technology and relates to an electric drive for a press. Moreover, the invention relates to a press with such a drive.

From the prior art directly driven servo presses are known. These require a very high torque during forming. For an optimized design, the operating point is placed within the range of the maximum power of the motor. Due to this boundary condition, the press motor is often oversized, since the generated torque peak is only needed for a certain work area and a motor with a very high speed and thus a low torque constant must be used.

A forming press with a direct drive using segment motors is off DE 10 2010 031 100 A1 known. In this case, a plurality of segment motors acting together on a shaft are used in order to generate high pressing forces and pressing speeds in a simple manner.

It is an object of the present invention to provide a solution with which a particularly advantageous combination of pressing force and dynamics is provided at comparatively low design effort. This object is achieved by an electric drive according to claim 1 or by a press according to claim 4. Advantageous embodiments of the invention are specified in the subclaims.

According to the invention, the drive has a first motor, which preferably acts directly, ie directly and without gear ratio, on the drive train of the press, and a second, acting directly on the drive train engine, which is only partially in this second motor equipped segment motor, only a portion of the second motor is equipped, which corresponds to the forming area and the second motor is energized only during the forming.

It is not essential to the invention that the first motor, which is also referred to below as a press motor, is designed as a direct drive. Instead, the first motor can also act on the drive train via a gear stage. It is essential, however, that the second engine, which is also referred to below as an additional motor is a teilbestückter segment motor, which acts as a direct drive, ie directly on the drive train.

The invention is based on the consideration that in a certain forming area (working area) for applying the forming forces, an increased torque is required. This forming area, in which the pressing forces applied by the press lead to changes in shape on the workpiece, is driven through slowly anyway, so that no highly dynamic plunger movements are necessary for this area. Servo presses are typically around 30 ° before UT (bottom dead center).

A key idea of the invention is now to maintain the already existing press motor as a drive motor, and to use a specially adapted to the forming area additional motor. The main features of these two engines are explained below.

The press motor serves, if at all, only to provide a comparatively small part of the required pressing force. Instead, it serves, depending on the design, exclusively or essentially to accelerate the ram when re-booting after the forming process. Before reaching the forming area again, the press motor slows down the ram and then slowly traverses the forming area. By such a highly dynamic movement of the plunger between the forming areas a high productivity of the press is ensured.

At the same time, the press motor can be smaller than previously customary dimensioned. For the press motor, a cost-optimized winding variant can be selected.

It is no longer necessary that the press motor reaches high speeds. As a result, the power consumption drops at the same Torque. The inverter used only needs a smaller and therefore more cost-effective power unit. In addition, an optimized working range or operating point can be designed for the press motor. This leads to an improved torque constant.

The additional motor is used exclusively for applying additional forces to generate the required pressing force. He intervenes when the forming process begins, that is after the deceleration of the plunger. In other words, the auxiliary motor is energized only during the forming and then serves to support the press motor. To the movement of the plunger between the Umformbreichen contributes the auxiliary motor, depending on the design, not or only insignificantly.

The additionally used segment motor is not fully populated. This means, for example, in the case of a radial segment motor that it is not equipped over the entire circumference of its rotor (360 °). The part assembly concerns both the windings or coils (primary part) and the permanent magnets (secondary part) of the motor. In other words, the auxiliary motor is wound only in a partial area and provided with magnets. According to the invention, this subregion corresponds to the deformation region, ie, for example, to a region of 30 °. In other words, the size of the populated partial area is adapted to the size of the working area. This avoids unnecessary assembly of the segment motor beyond the working range.

If instead one would use a fully equipped motor as an additional motor, as is known from the prior art, this would have to be designed in all points for the maximum speed between the forming areas. This is no longer necessary. The maximum speed of the additional motor is the forming speed. The additional motor can therefore also be constructed very cost-optimized.

It goes without saying that the additional motor is designed such that in the work area superimposed primary and secondary parts congruent. Also on the use of control, regulation and monitoring devices that accomplish the interaction of press engine and auxiliary motor should not be discussed further at this point, as is familiar to those skilled in the art.

With the invention, a press drive is provided in which pressing force and dynamics are combined with each other in an optimal manner. By using the invention, the number of different engines to be kept ready can be reduced since the same press motors can always be used. Changing demands for higher torques can be achieved by a higher population of the additional motor.

The assembled section of the segment motor does not have to be a closed section. For example, it may be advantageous to equip two or more subregions spaced apart from one another. It is particularly advantageous if two opposing segments of the additional motor are equipped, in other words, the populated segments are arranged on the rotor offset by 180 ° to each other. As a result, not only can an imbalance be avoided, at the same time the double torque can be achieved. If, instead, only the equipping of a single segment is provided, then advantageously a counterweight is attached to avoid an imbalance on the opposite side of the rotor.

The invention is not limited to drives for presses with servo drive technology. It can also be used for drives of other presses. Also on the number of motors used is not important. Thus, instead of a press motor and several press motors and / or several auxiliary motors can be used instead of an additional motor. Also, the invention is not limited to radial segment motors limited, but can also be realized when using other segment motors. In addition, the invention is also independent of the operation of the motors used. For example, it is irrelevant to the invention whether an internal rotor or external rotor arrangement is selected.

FIG 1

eine Seitenansicht des Antriebs einer Servopresse,

FIG 2

eine Vorderansicht des Antriebs aus FIG 1.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which will be described in detail in conjunction with the drawings. Showing:

FIG. 1

a side view of the drive of a servo press,

FIG. 2

a front view of the drive FIG. 1 ,

All figures show the invention only schematically and with its essential components. The same reference numerals correspond to elements of the same or comparable function.

The invention will be explained by way of example with reference to an eccentric press which generates the pressing force with the aid of an eccentric shaft. Shown is the drive train 1 a servo press with eccentric shaft 2, connecting rod 3 and plunger 4. A press motor 5 is connected via a gear stage 6 with a low gear ratio with the eccentric shaft 2. In addition, an auxiliary motor 7 is connected directly to the eccentric shaft 2. In other words, the auxiliary motor 7 is designed as an electric direct drive with an immediate effect on the drive train. Transmission gears, gears or the like are not used.

The press motor 5 is a comparatively small dimensioned torque motor. The auxiliary motor 7 is a radial segment motor. The auxiliary motor 7 comprises a partially populated coil system (primary part) and a partially loaded permanent magnet system (secondary part) cooperating with the coil system.

The coils 8 and the permanent magnets 9 are combined into groups and thereby arranged in segments. The coils 8 can be controlled separately in segments. In FIG. 2 shown is the time in which the auxiliary motor 7 is energized. Primary and secondary parts 8, 9 overlap congruently in a forming area 11 of about 30 ° before UT.

In the illustrated example, two populated segments 12, 13 are used. The segments are offset by 180 ° to each other, so that they are opposite each other. As a result, an imbalance of the rotor is avoided.

In the forming area 11, the required pressing force is applied by means of the additional motor 7. Subsequently, the press motor 5 is used to accelerate the plunger 4 again and decelerate before the next forming process. Then a renewed slow driving through the forming area 11 takes place.

Although the claims have been further illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Thus, in the implementation of the invention, for example, several press motors, auxiliary motors and / or eccentrics are used, although in the figures, only one press motor and an additional motor are shown.

Claims (5)

1. Electric drive for a press, having a drive train (1) which repeatedly passes through a forming region (11), and having a first motor (5) acting on the drive train (1) directly or via a gear stage (6), and having a second motor (7) acting on the drive train directly, wherein the second motor (7) is a partly-loaded segment motor, characterised in that a subregion of the second motor (7) corresponding to the forming region (11) is loaded and the second motor (7) is only powered during the forming.
2. Drive according to claim 1, wherein the second motor (7) is a radial segment motor, in which two opposing segments (12, 13) are loaded.
3. Drive according to claim 1, wherein a counterweight for equalising an imbalance is arranged opposite the loaded subregion of the second motor (7) on the rotor of the second motor (7).
4. Press having an electric drive according to one of claims 1 to 3.
5. Press according to claim 4, wherein the press is an eccentric press and the first motor (5) and the second motor (7) are connected to the eccentric shaft (2) of the press.

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