Patent Application
20190091822
The present invention concerns a machine element, in particular for a shaping machine, having a lubricated bearing and/or a seal and at least one drainage conduit for catching a medium issuing from the bearing and/or the seal, preferably substantially pressure-lessly, in accordance with the features of the classifying portion of claim 1, and a corresponding method.
The state of the art is illustrated hereinafter by reference to the example of a rotary feedthrough.
Rotary feedthroughs as are used in particular in shaping machines like for example injection moulding machines make it possible for media circulations, in particular of fluid, that is to say gaseous or liquid media, to be transmitted from a component to a shaft which rotates in relation to the component.
The media passages of those rotary feedthroughs are provided with annular seals on the one hand to prevent the media from issuing from the media passage and on the other hand to prevent the media being contaminated by oil or grease coming from the lubrication for the shaft bearing means.
It will be appreciated that, in dependence on the operating hours of the bearing locations or seals, leakage occurs both in respect of the lubricant and also in respect of the media. Drainage conduits are provided for that purpose, which open for example into a container.
It is also known in the state of the art to provide pressure sensors in the drainage conduits. By virtue thereof the operator of the installation can be warned if damage to the rotary feedthrough occurs, and as a result larger amounts of lubricant or media issue and possibly contaminate each other.
Admittedly that system relatively reliably provides information about damage or at least increased leakage at the rotary feedthrough. If however the pressure in the drainage conduit is already increased the risk of mutual contamination naturally already arises, that is to say in general damage has already occurred.
The object of the invention therefore is to provide a rotary feedthrough in which impending damage or at least an increase in a leakage rate can already be detected, as well as providing a corresponding method.
That is effected by at least one collecting device for collecting the medium which is caught in the at least one drainage conduit over a period of time, and a measuring device adapted to directly and/or indirectly measure an amount of the medium collected by means of the at least one collecting device over the period of time.
That is effected by medium issuing from the bearing and/or the seal being collected over the period of time and the amount of the medium collected over the period of time being directly and/or indirectly measured.
The invention can therefore be used not only in rotary feedthroughs but quite generally in relation to machine elements having a lubricated bearing and/or any machine elements having seals, that is to say in particular in almost any kind of rolling bearings and/or plain bearings.
The medium which is carried away by the at least one drainage conduit can be lubricant from the bearing, media in relation to which the seal provides sealing integrity, or mixtures thereof. In other words, anything which can issue from a seal and/or a bearing is deemed to be medium in accordance with the invention.
A basic aspect of the invention provides collecting an amount of the issuing medium with the collecting device, which makes it possible to carry out measurement of the amount with reasonable accuracy. As in general the issuing medium is substantially pressure-less (in comparison with the ambient pressure) direct volume flow measurement can normally not be carried out with acceptable accuracy. (The volume flows can be in the region of ml/month.)
It is therefore possible by means of the invention to detect increased leakage at an early time—and thus inter alia also damage to the corresponding machine component at an early time—. Bearings and/or seals can thus be subjected to “condition monitoring”.
The apparatus according to the invention can be adapted to measure the amount of the medium collected by means of the at least one collecting device during and/or after the period of time, wherein the period of time is preferably established in advance. For example the at least one drainage conduit can be shut off by a stop valve and periodically emptied by brief opening thereof. If a pressure sensor is available (which is in the normal situation present in any case) it is possible to conclude about the amount of leakage on the basis of the information as to how fast the pressure rises. If for example after emptying of the drainage conduit the pressure rises significantly faster than was previously the case, it is possible to initiate maintenance or a change of the corresponding machine element.
As a measurement of the leakage rate however it is also possible to use a measured period of time which elapses until a predefined amount of the medium is collected. In particular it can preferably be provided that the measuring device is adapted on the one hand to measure a property, that varies with the amount of the collected medium, of the medium which is collected by means of the at least one collecting device and on the other hand to measure the period of time, wherein a measurement value of the period of time at a moment in time at which a measurement value of the property of the collected medium reaches and/or exceeds a limit value serves as a measurement in respect of the amount of the medium collected over the period of time.
That can be achieved for example by a pressure limiting valve. Normal leakage means that the pressure in the at least one drainage conduit rises slowly. If the pressure exceeds the limit pressure of the pressure limiting valve the valve is opened and the pressure falls in the at least one drainage conduit. The latter can be detected for example again by way of a pressure sensor or the like. If the frequency at which the pressure limiting valve responds rises it is possible to assume that there is increased leakage and maintenance or a change in the machine element can be initiated.
In general the amount of collected medium, however it is measured, can be observed, and then maintenance or replacement of the machine element can be carried out if the amount per unit of time (or alternatively the period of time per unit of amount) rises—significantly—.
Examples of machine elements which can be monitored according to the invention would be a hydraulic cylinder having at least one sealed pressure chamber or a rotary feedthrough which preferably has a plurality of mutually sealed media conduits.
In particular in the latter case it can be provided that there are separate drainage conduits for the various media conduits. That however is possible not just in relation to rotary feedthroughs. Whenever there are a plurality of various media or a plurality of various locations at which the medium issues on a machine element separate drainage conduits can be used.
If there are a plurality of (separate) drainage conduits respective separate collecting devices can be associated therewith. In that way it is possible to quickly and easily find out where precisely an increased leak is occurring.
In a particularly simple configuration the separate drainage conduits can naturally also be brought together to a main drainage conduit, in which case then the at least one collecting device can be arranged in and/or at the main drainage conduit.
The collecting device can have at least one of the following:
a stop valve arranged in the at least one drainage conduit,
a pressure limiting valve arranged in the at least one drainage conduit, and/or
a container connected to the at least one drainage conduit.
In a quite simple configuration however measurement of the collected medium could also be implemented by visual checking at a corresponding collecting container. The measuring device would then be implemented by a viewing window on the corresponding collecting container or by a transparent collecting container.
For the purposes of this document the expression container connected to the at least one drainage conduit is used to mean any container in which a fluid of the at least one drainage conduit opens without support from the exterior. The possibility has already been mentioned, of providing a pressure sensor for detecting a pressure in the at least one drainage conduit and using it as a measuring device in accordance with the invention.
Protection is also claimed for a shaping machine having a machine element according to the invention.
Herein, the term “shaping machines” means injection moulding machines, injection presses, presses and the like.
Further advantages and details of the invention will be apparent from the Figures and the related specific description.
In the drawing:
The machine element 1 shown in
There are also a plurality of separate drainage conduits 5 which all open into a main drainage conduit 4.
In that respect it is to be mentioned that the main drainage conduit 4 can be composed of a main drainage passage in a component of the rotary feedthrough and a flexible or non-flexible conduit portion connected thereto, like for example a tube or a hose. In the present embodiment a stop valve which for example is in the form of a two-way valve serves as the collecting device 6. A corresponding stop valve can be actuated electrically or electronically, in which respect theoretically it is also possible to use a hand-operated stop valve. In addition there is a measuring device in the form of a pressure sensor.
The stop valve can be opened at regular intervals and thereafter it is possible by means of the pressure sensor to observe how quickly the pressure rises. If that occurs significantly faster than in previous observation cycles it is to be assumed that there is increased leakage.
It is to be noted that not all seals 3, media passages 9 and separate drainage passages 5 are provided with reference numerals in order to maintain clarity of the drawing.
More specifically in
The collecting device 6 and measuring device 7 according to the invention are of a similar structure to the example of
The second example would be a weighing device as the measuring device 7, on which the container is arranged. The mass of the medium in the container or a similar value can be detected by the weighing device.
The two embodiments illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| A 50809/2017 | Sep 2017 | AT | national |
