Patent Application
20210388879
The present invention relates to a method for operating a combined clutch and brake device of a punch press equipped with dry friction linings, a combined clutch and brake device for carrying out the method, and a punch press with the clutch and brake device according to the preambles of the independent patent claims.
Dry-running clutch-brake combinations have become established in high-performance automatic punch presses. These transmit their torque via friction by means of organic friction linings. The actuating pistons in the clutch and brake are supplied with compressed air via special safety valves, which usually contains moisture and is enriched with oil. During shifting, this moisty and oily air is released into the environment of the punch press. Additional oil is released into the ambient air by spraying the to be processed strip material with cutting oil. The air that is thus enriched with oil and water vapor comes into contact with the friction linings of the clutch-brake combination during operation, causing them to become increasingly oily with increasing operating time and worsening the clutch and brake torque until replacement or cleaning of the linings is required. Since the linings are usually not subject to any substantial wear that would require regular replacement, the costs and downtimes incurred by replacing or cleaning the oily linings are particularly unpleasant.
Therefore, the objective here is to provide a technical solution that does not have the disadvantages of the prior art described above or at least partially avoids them.
This objective is achieved by the subject-matter of the independent patent claims.
According to these, a first aspect of the invention relates to a method for operating a combined clutch and brake device of a punch press equipped with dry friction linings. According to the invention, the friction linings of the clutch and brake device are thereby arranged in a chamber sealed off from the environment of the punch press, e.g. in a housing surrounding the clutch and brake device, which is filled with a gaseous and essentially dry and oil-free medium, e.g. with dry oil-free air. This effectively prevents moisture and oil mist from entering the region of the friction linings from the environment of the press, and a constant friction coefficient can be achieved over the mechanical service life of the friction linings.
Preferably, the chamber is pressurized with the gaseous medium under overpressure during the intended operation and even more preferably also during any putative operating breaks. In this way, in the event of leaks, no foreign medium possibly contaminated with oil and/or moisture can enter the chamber and possibly change the friction coefficient of the friction linings.
In a preferred embodiment of the method, the gaseous medium is set in motion in the chamber during the intended operation, e.g. circulated in the chamber by means of forced convection. This allows heat to be transported away from the friction linings to the boundaries of the chamber and to be transferred to them. Also a uniform temperature distribution in the chamber can be achieved thereby, which is particularly advantageous if the temperature of the gaseous medium is monitored and used to control certain interventions, e.g. to control the replacement of heated gaseous medium in the chamber by new, cooler gaseous medium when a certain threshold temperature is reached or to trigger an emergency stop if there is a risk of overheating of the friction linings.
In another preferred embodiment of the method, gaseous medium is supplied to and discharged from the chamber continuously, intermittently, or under specific operating conditions.
For example, it is envisaged that a certain amount of gaseous medium permanently flows out of the chamber, e.g. into the environment, via one or more discharge openings with a small flow cross-section and is replaced by newly supplied medium, so that there is a permanent exchange of medium in the chamber and thus a concomitant removal of heat from the chamber. Thereby, the discharge openings should be dimensioned in such a way that, if possible, only as much medium flows out as is necessary to transport away the heat generated or to maintain a desired medium temperature in the chamber, respectively. The discharge openings can be designed with fixed or variable flow cross-sections.
It is also envisaged that a complete or partial medium exchange or flushing of the chamber with fresh dry and oil-free gaseous medium, respectively, is carried out intermittently, e.g. every 5 minutes during the intended operation, or only if certain operating conditions are present, e.g. if it is necessary to stop and restart several times with a very high stroke rate or if it is necessary to inch for a long time in setup mode. It can also be envisaged, for example, that a medium exchange is initiated in a temperature-controlled manner, e.g. if a certain temperature is reached in the chamber.
In a preferred embodiment of the method, in which dry and oil-free gaseous medium is supplied to the chamber and discharged from the chamber permanently, intermittently or under specific operating conditions, the discharged medium is released into the environment of the punch press. In this way, an extremely simple method becomes possible which requires a minimum of technical equipment.
Thereby, it is in a first variant preferred that the dry and oil-free gaseous medium supplied to the chamber is air, which is drawn in from the environment of the punch press, cleaned, dried and/or de-oiled by means of a treatment device and then supplied to the chamber. In this way, any quantities of dry and oil-free gaseous medium can be made available in a simple manner.
In a second variant, it is preferred that the dry and oil-free gaseous-medium supplied to the chamber is supplied to the chamber from a reservoir. This has the advantage that a particular gas atmosphere can specifically be created in the chamber, e.g. of nitrogen or helium.
In another preferred embodiment of the method, the chamber is part of a circuit in which, during the intended operation, the gaseous medium which is discharged from the chamber is subjected to a treatment and then re-supplied to the chamber.
Preferably, the treatment includes a cooling of the medium. Other preferred treatments include dehumidifying/de-oiling of the medium and/or a cleaning of the medium, e.g. filtering.
Such methods with closed medium circuits have the advantage that with very small quantities of gaseous medium a constant medium environment for the friction linings in terms of both medium temperature as well as medium composition can be created, so that the same friction conditions are always present at all times.
A second aspect of the invention relates to a combined clutch and brake device for carrying out the method according to the first aspect of the invention, which is equipped with dry friction linings for transmitting the drive and brake torques.
The friction linings of the clutch and brake device are arranged in a chamber which is sealed off from the environment of the punch press, e.g. in a housing surrounding the clutch and brake device, which during the intended operation is filled with a gaseous and essentially dry and oil-free medium, e.g. with dry oil-free air. Thereby, an entry of moisture and oil mist into the region of the friction linings from the environment of the press is effectively prevented and thus a constant friction coefficient is enabled over the mechanical service life of the friction linings.
Preferably, the clutch and brake device is designed in such a way that the chamber can be pressurized with the gaseous medium at an overpressure during the intended operation, and even more preferably also during any putative operating breaks. In this way, in the event of leakages, no foreign medium possibly contaminated with oil and/or moisture can enter the chamber and possibly change the friction coefficient of the friction linings.
In a preferred embodiment, the clutch and brake device has means, e.g. internal fan blades, by means of which the gaseous medium can be set in motion in the chamber during the intended operation, e.g. can be circulated in the chamber by means of forced convection. In this way, heat can be transported away from the friction linings to the boundaries of the chamber and dissipated to them. Also a uniform temperature distribution in the chamber can be achieved thereby, which is particularly advantageous if the medium temperature is monitored and used to control certain interventions, e.g. to control a replacement of gaseous medium heated in the chamber by new, cooler gaseous medium when a certain threshold temperature is reached or to trigger an emergency stop if there is a risk of overheating of the friction linings.
In a further preferred embodiment, the chamber has supply and discharge openings through which, during the intended operation, gaseous-medium can be supplied to and discharged from the chamber permanently, intermittently or under certain operating conditions.
For example, it is envisaged that the chamber has one or more discharge openings through which, during the intended operation, a certain amount of gaseous medium permanently flows out of the chamber, e.g. into the environment, and is replaced by newly supplied medium, such that that there is a permanent exchange of medium in the chamber and thus a concomitant removal of heat from the chamber. The discharge openings are preferably dimensioned in such a way that only as much medium flows out as is necessary to remove the heat generated or to maintain a desired medium temperature in the chamber, respectively. The discharge openings can have fixed or variable flow cross-sections.
Thereby, in a first variant of this embodiment, it is preferred that the clutch and brake device comprises an air treatment device by means of which air can be drawn in from the environment of the punch press during the intended operation, cleaned, dried and/or de-oiled, and then supplied to the chamber. In this way, any desired quantities of dry and oil-free gaseous medium can be made available in a simple manner.
In a second variant of this embodiment, it is preferred that the clutch and brake device comprises a reservoir for the gaseous and essentially dry and oil-free medium, from which this medium can be supplied to the chamber. This has the advantage that a specific gas atmosphere can be created in the chamber, e.g. of nitrogen or helium.
In a third variant of this embodiment, it is preferred that the chamber is part of a circuit in which the gaseous medium is circulated during the intended operation.
Advantageously, means are arranged in the circuit for treating the gaseous medium circulated therein during the intended operation, preferably for cooling, dehumidifying and/or de-oiling of the gaseous medium circulated therein.
It is also preferred that cleaning and/or filtering devices are present in the circuit for cleaning and/or filtering the gaseous medium circulated therein during the intended operation.
Such embodiments of the clutch and brake device according to the invention with closed medium circuits have the advantage that with very small quantities of gaseous medium, a constant medium environment can be created for the friction linings with regard to both the medium temperature and the medium composition, such that the same friction conditions are always present at all times.
A third aspect of the invention relates to a punch press with a clutch and brake device in accordance with the second aspect of the invention. In such machines, the advantages of the invention are particularly apparent.
Further preferred embodiments of the invention are apparent from the dependent claims and from the now following description with reference to the figures. Thereby show:
The press 1 is arranged in a closed soundproofing booth, of which only a section of a side wall 15 is shown.
The cover 12 has a supply port 13 for clean dry air on its upper side and is passed through centrally in the axial direction by the belt pulley 14 for the drive belt (not shown), thereby forming a narrow sealing gap S between the belt pulley 14 and the cover 12 (see
As can be seen in
As can be seen in particular from the arrows shown in
If the air in the vicinity of the soundproofing booth is contaminated with dust, moisture and/or oil mist, the axial fan 16 is followed by devices for appropriate treatment of the air drawn in (filtering/dehumidifying/de-oiling), which the air must pass through before it is supplied to the chamber R.
The
The
As can be seen in the
While preferred embodiments of the invention are described in the present application, it should be clearly noted that the invention is not limited thereto and may be carried out in other ways within the scope of the now following claims.
This application is a National Stage application of International Patent Application No. PCT/CH2018/000042, filed on Oct. 22, 2018, which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CH2018/000042 | 10/22/2018 | WO | 00 |
