DE19545004A1 - Directly-regulated electric spindle press drive - Google Patents

Abstract

The drive uses an asynchronous electric motor and an electronic current regulator for varying the drive revs to provide accurate regulation of the required displacement/time characteristic, to match the technological process. The acceleration and retardation times can be accurately regulated in the millisecond range, with the motor rotated at a constant revs after the acceleration phase.

Description

Screw presses are preferably with directly coupled electric drive motors Asynchronous motors. To accelerate in the lifting or lowering direction, a direct switching on of the asynchronous motor to the network. Do this accordingly high inrush currents, which results in considerable loads for the switching elements and surrender the engine. The duty cycle of the motor depends on the one to be moved Masses and the required path-time course. As a result, inevitable Switch-on delays at the power switch occur within tolerances of the actual travel-time curve compared to the required target path-time curve.

In this respect it has technological Disadvantages that the available forming energy of the required value deviates and the deformation process is insufficiently defined.

When designing the screw presses, a certain amount of energy is required or to increase the energy, an additional flywheel is built in. during the lifting process and in the delay to reach the top dead center position speed up.

According to the invention, the disadvantages mentioned are to be eliminated as follows.

If the asynchronous motor is switched on directly by a speed variable Three-phase drive consisting of three-phase asynchronous motor and frequency controller replaced, see above the possibility of precise regulation of the path-time curve is given. Acceleration and deceleration times can be accurate in the millisecond range be respected. The energy available for forming can also be used simple electronic means can be adapted to the technological process. In order to there is a hitherto unprecedented technological flexibility of the press. The Process execution times can be shortened and the energy losses that occur can be reduced will. It is still possible to run the engine at a higher speed without To extend the process time if the engine is not used  goes through a phase with constant speed after the acceleration phase. As a result, according to:

With
j = moment of inertia
ω = angular velocity
m = mass
v = speed of movement

the energy stored in the rotating system is greater. It can therefore be the flywheel the press can be reduced in size and possibly even an additional flywheel omitted. For the press, this means a reduction in the total mass and the mecha dimensions.

Claims (4)

1. Electrically driven screw press, characterized in that to improve the energy balance of the drive by a variable-speed drive consisting of motor and converter 2. Electrically driven screw press according to claim 1, characterized in that to reduce or even avoid additional flywheels driven a higher maximum speed by means of the variable speed drive becomes. 3. Electrically driven screw press according to claim 1 and 2 characterized net that the required forming energy by varying the speed to the Technology is adapted. 4. Electrically driven screw press according to claim 1, 2 and 3 characterized thereby records that to adapt to the technological process of speed-time Ver run the spindle (distance-time course of the ram) by means of a device Control or regulation of the drive is varied.