DE2334673C3 - Wave training - Google Patents

Description

The invention relates to a shaft formation consisting of a shaft and one arranged on it Guide ring with approximately the same thermal expansion as the shaft and one held by the guide ring, the shaft with clearance surrounding the shaft sleeve made of a material that has a different coefficient of thermal expansion than the material of the shaft.

It is known that shafts do not run directly into plain bearings and other constrictions in the housing but rather to provide shaft protection sleeves at such areas at risk of contact. Next to the Such sleeves enable shaft protection to otherwise not be feasible.

The invention relates to shafts running at high temperatures and having bearings lubricated by the pumped medium or sealing points, with bearings and shafts having different coefficients of linear thermal expansion to have. It is well known that bearings and sealing points must have a certain play that is within narrow limits to ensure that the machine runs properly. In the following text, for the sake of simplicity only spoke of bearings, with sealing points to be included. Has the Bearing shell, for example, has a higher coefficient of thermal expansion than the shaft, so will deal with increasing temperature, the bearing play increases and can assume impermissible values, the constructive Make countermeasures unavoidable. The reverse can also happen, either with the same material combination at very low temperatures working bearings, where then impermissible close Games occur, or the reverse combination of materials as well at high temperatures.

Here, too, shaft protection sleeves are used that are made of material with the same or approximately the same Manufactures thermal expansion coefficient and the bearing shell. This means that the games in the Warehouse secured. The problem is not solved, but only postponed: It is now constructive Measures are required to ensure that the shaft protecting sleeve is properly seated on the shaft.

For this purpose you have so far z. B. the leadership by three or more keys, splined shafts or occasionally also used simply by criss-crossing pins. All these tools have in common that the radial thermal expansion in the event that the shaft sleeve expands more than the shaft, unhindered, but takes place purely radially due to the form-fitting guidance and consequently the centers of the shaft and protective sleeve always coincide. An analogy is the management of turbine housings or something similar thermal turbo machines. However, this remedy can only be used to a limited extent if the circumstances are such that that the seat of the shaft sleeve becomes more and more tight, d. H. the shaft expands more than the sleeve.

Another well-known technical aid is the so-called "cold-warm fit" for the case of the when the temperature rises, the shaft protection sleeve expands more strongly on a ferritic shaft at higher temperatures Temperatures centered With this »cold-warm fit«, the shaft protection sleeve sits at normal temperature on the shaft with a snug fit. When the temperature rises, the seat loosens a little, and instead lies down the outer centering in the bore of the ferritic guide ring. The leadership then continues this ensures that the guide ring is guided in a snug fit from the shaft and in turn over the seat the shaft protecting sleeve leads. As the explanation suggests, this is not without mutual hindrance possible, but this is manageable to a certain extent, provided that they are in engagement with one another standing parts are appropriately dimensioned, sufficient decay lengths are provided for the deformation and the temperatures are not too high. From one of the material properties and the construction Depending on the temperature difference, however, there are either higher games in the snug fit or plastic ones To accept deformations and thus again similar games. They cause that at medium temperatures the guide is lost and eccentricities of the shaft protecting sleeve on the shaft are immediately apparent and in the wake of these imbalance excitations, one-sided rubbing and the like cease.

In addition, the guide ring sitting on the shaft will usually turn inside out if it is not very long can be executed. Edge pressure then occurs on one edge of the snug fit. This hinders the necessary axial thermal expansion of the shaft protecting sleeve, possibly up to self-locking, or, what is even more unfavorable, a one-sided yielding of this clamping on the shaft can generate tensioning bending moment and thus lead to unsteady wave run.

The object of the present invention is to overcome the disadvantages described and the practically possible temperature range to expand considerably. This task is turned away from known double fit principle in shaft designs of the type mentioned according to the invention solved in that the shaft sleeve is made of austenitic material and with that made of ferritic Material existing guide ring axially adjoining it, is firmly connected. The shaft protection sleeve, which performs the bearing function is integral with the guide ring (by welding, soldering, riveting or the like) tied together. In this way, guides and fits that differ from normal in do not distinguish in any way and are therefore also safe against vibrating or shock loads Knocking out or otherwise getting rid of. In addition, there is the extended scope of application.

visible temperature and tension.

It is true that bearings or seals have become known with a somewhat similar combination of materials (US-PS 29 70 019, CH-PSn 4 00 680, 3 41363 and DE-OS 20 00 601) which, however, all ι eight the Features essential to the invention of the subject of avoidance, since they are not all like the same are designed against any voltage differences, require additional items and more are functionally dependent on a specific shape and the structural complexity in this context is very high

A particular advantage of the teaching according to the invention is that this principle also applies to the case of At the operating temperature, the shaft sleeve can easily be tightened so in this previously not easily manageable case, use combinations of materials that were previously were not useful if it came down to compliance with certain games.

An advantageous development of the invention can be in the area of the connection between the austenitic and the ferritic part of the wave formation can be provided with a groove to shorten the decay length. It is also possible, for extreme cases, to place one or more buffer pieces between the austenitic and the to arrange ferritic part, these buffer pieces have coefficients of thermal expansion that value between those of the two parts mentioned. Further details of the invention are as follows To be found in the description.

The drawings illustrate exemplary embodiments of the invention;

F i g. 1 the basic principle of the invention with two different ring parts welded to one another Thermal expansion that

F i g. 2 an embodiment variant with an additional groove or recess and the

3 shows a further embodiment variant with a Intermediate piece whose coefficient of thermal expansion lies between that of the neighboring rings.

On the shaft 1 sits a Weüenschutzhülse 2, which from austenitic material and is connected to a ferritic guide ring 4. The ferritic one Guide ring 4 takes over the guidance of the shaft 1 and the austenitic shaft protection sleeve with the snug fit 5 2 has a storage function. The parts 2 and 4 are by means of a weld 6 to form an integral unit tied together; Instead of a weld seam, a solder or rivet connection or the like can of course also be used.

be used.

The area to the right and left of the weld seam is a transition zone that is neither for fit nor for Storage purposes come into question The length of this

5 transition zone in which the deformations as a result of the With knowledge of the teaching according to the invention, one can use known formers to decay material continuity calculate from the strength theory depending on the desired degree of decay.

ίο Fig.2 shows a variant that a since the decay length is roughly proportional to the root of the Wall thickness, the unusable length can be shortened in this way. This is further facilitated by that the comparatively much thicker and thus more rigid parts essential for the actual function of your thinner connector in their behavior are less affected. Of course, the groove 7 can also be arranged on the outside will.

F i g. 3 shows a further variant that is suitable for even higher temperatures or for reducing the stresses that occur in the material as a result of the hindrance to thermal expansion. which lies between that of parts 2 and i . So the same idea is applied twice in a row

ίο In this case, however, not twice the decay length to be provided, but part 8 will be provided much shorter, so that it is between the deformations of the Parts 2 and 4 conveyed to a certain extent For this case, there are hardly any ready-made formulas in the literature linden, but you can use one of the shell programs to proceed relatively quickly with an iterative procedure get solutions that are inexpensive in terms of tension and effort. The solutions in Fig.2 and 3 can be combine.

In Fig. 4 shows the behavior of this association under temperature. Where is the radial displacement applied over the length. The dash-dotted line is that of the ferritic shaft. The undressed Line is the expansion of the shaft protection sleeve. Achieved by appropriate choice of the position of the weld seam one that the snug fit remains cylindrical and just joins the displacement of the shaft surface while the part of the shaft sleeve, which is essential for the bearing function, is also cylindrical, the austenite thermal expansion executes.

For this purpose 2 sheets of drawings

Claims (3)

Patent claims: 1. Shaft training, consisting of a shaft and a guide ring arranged on it with approximately the same thermal expansion as the shaft and one held by the guide ring, the Shaft with clearance surrounding shaft sleeve made of a material that has a different coefficient of thermal expansion than the material of the shaft, characterized in that the shaft protecting sleeve (2) consists of austenitic material and with the one made of ferritic material Guide ring (4) axially adjoining it, is firmly connected 2. Wave formation according to claim 1, characterized by a groove (7) for shortening the Decay length. 3. Wave formation according to claim 1 or 2, characterized by one or more buffer pieces (8) with coefficients of thermal expansion between those of parts (2) and (4).