Manufacturing container or tube from paper; or other manufacturi – Control means energized in response to activator stimulated... – Responsive to work material – the product or means engaging...
Reexamination Certificate
1998-12-03
2001-02-20
Vo, Peter (Department: 3721)
Manufacturing container or tube from paper; or other manufacturi
Control means energized in response to activator stimulated...
Responsive to work material, the product or means engaging...
C493S207000, C493S209000, C053S075000, C053SDIG002, C156S073400, C156S580200, C100S050000
Reexamination Certificate
active
06190296
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for machining a material web with an ultrasonic unit having a sonotrode and with a counterstay tool, the material web being led through a nip between the sonotrode and the counterstay tool and being machined by the sonotrode, the sonotrode being clamped in a slide and the slide being adjustable in relation to the counterstay tool via an adjusting device, with a sensor connected to a control or regulating device which brings about a change in the clearance between the slide and the counterstay tool, as a function of the signal from the sensor.
In addition to rotary punching and cutting rollers, by means of which endless material webs are machined, ultrasonic sonotrodes are increasingly being used, by means of which the material web is connected, cut, perforated, punched, embossed, heat-treated or similarly machined. A critical factor, with regard to both conventional punching and cutting rollers and sonotrodes, is that the nip between the tip of the machining tool and the counterstay tool, which may be a rotating roller or a plane surface, should have a constant height. The material web to be machined, which may also consist of a plurality of layers, is led through this nip. Due to the heat which is generated during machining, the length of the machining tool, for example the sonotrode, changes, and this may lead to a change in the nip height. As a rule, however, a nip which is too narrow leads to a deterioration in the machining of the material and, under certain circumstances, may result in damage to the material web or the tools. Too wide a nip give s an unacceptable sealing quality or cutting quality. The aim, therefore, is to keep the nip as constant as possible.
In an apparatus for the continuous ultrasonic machining of a material web, which became known from DE 44 39 284 A1, the welding nip can be adjusted via an adjusting device. It is proposed to design the adjusting device as a piezoelectric actuator. By means of piezoelectric actuators of this type, the cutting nip may, indeed, be set at a very exact height, but it is scarcely possible for large changes in the nip to be made.
An apparatus for the ultrasonic machining of a material by means of a sorotrode is known from DE 195 26 354 C1. This apparatus has a sensor, by means of which the distance between the sonotrode and the counterstay tool can be measured. The nip clearance is thereby set via the signal from the sonotrode.
The object on which the invention is based is to develop an apparatus of the type initially mentioned, in such a way that, by means of said apparatus, an essentially constant nip for machining the material web is maintained, the apparatus being set relatively quickly to changing material and/or machining parameters.
SUMMARY OF THE INVENTION
In an apparatus of the type initially mentioned, this object is achieved, according to the invention, in that the sensor is a force sensor and a force acting on the sonotrode in the direction of the counterstay tool can be measured via the sensor.
The apparatus according to the invention has the essential advantage that the pressure force of the sonotrode can be determined directly or indirectly via a force measurement, and that, if this force changes, the sonotrode can be displaced in the direction of the counterstay tool or away from the latter. The optimum pressure force is determined by means of tests and the associated measurement value of the sensor is stored as an actual value in the control or regulating device. If, then, the force detected by the sensor changes while the apparatus is in operation, the measurement value of the sensor changes, this value being used as a control variable for the control or regulating device. As a function of this changed measurement value, the position of the sonotrode is changed in such a way that it once again rests on the material web with the same pressure force. Simple, inexpensive and, above all, rapid readjustment is possible in this way.
In a development of the invention, a toggle lever system is provided, via which a pressure force can act on the sonotrode in the direction of the counterstay tool. The sonotrode can be relatively simply advanced in the direction of the counterstay tool or moved away from the latter via this toggle lever system. Moreover, relatively high forces can be generated, whilst at the same time the actuating force can be relatively low. Furthermore, the pressure force can be metered very finely via the toggle lever system. Since the toggle lever is very rigid in the extended or virtually extended state, the return forces acting on the sonotrode when material thickenings occur are very high, so that the nip between the sonotrode and the counterstay tool can be kept constant.
Advantageously, the sensor is provided in or on the toggle lever system or in or on a toggle lever arm. By a change in the position of the toggle joint of the toggle lever system, the forces within the toggle lever system, in particular within the toggle lever arm, are changed, and this can be detected by means of the sensor. Moreover, the forces within the toggle lever system change when the height of the machining nip changes or when the parameters of the material to be machined change.
Preferably, the sensor is arranged in or on the toggle lever arm facing away from the sonotrode. This affords the advantage that the vibrations of the sonotrode are damped virtually completely via the toggle lever system and the sensor is influenced only minimally by these vibrations.
There is provision, in embodiments, for the sensor to be a wire strain gauge, a piezoelectric element or a load cell. In particular, designing the sensor as a wire strain gauge has the essential advantage that, on the one hand, the weight of the sensor is negligible and, on the other hand, the forces occurring in the toggle lever system, in particular on the toggle lever arm, can be measured with great accuracy and without any time delay and the measurement quantity can be used directly, or, if appropriate, with an amplifier being interposed, as an actuating variable in the control or regulating device.
A simple and accurate change in the pressure force is achieved if the control or regulating device has a stepping motor acting on the toggle joint of the toggle lever system. A stepping motor of this type can act on the toggle lever system with great sensitivity and change the pressure force of the sonotrode on the material web.
REFERENCES:
patent: 3534442 (1970-10-01), Mahle
patent: 4048004 (1977-09-01), Waltkins
patent: 4758293 (1988-07-01), Samida
patent: 4854494 (1989-08-01), Von Raben
patent: 5197371 (1993-03-01), Van Der Heijden et al.
patent: 5379688 (1995-01-01), Ishii
patent: 5622026 (1997-04-01), Pozzini et al.
patent: 5673615 (1997-10-01), Kawakami
patent: 34 10 954 A1 (1984-03-01), None
patent: 195 26 354 C1 (1995-07-01), None
patent: 44 39 284 A1 (1996-04-01), None
Gnad Gerhard
Rau Stefan
Vogler Ulrich
Birch & Stewart Kolasch & Birch, LLP
Desai Hemant M.
Ultraschalltechnik GmbH & Co. KG
Vo Peter
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