SE454800B - SEALING DEVICE FOR A SLIDING CONNECTION AND THE USE OF TWO CONNECTING BODIES FOR THE IMAGE OF A SEALING DEVICE - Google Patents

Description

15 20 25 30 35 454 800 _ 2 hard and dense material with poor thermal conductivity. On the other hand, it has been found that even with low wetting there is always a certain adhesion between the plate material and the melt, and when maneuvering the closure a "retraction" of small amounts of melt between the plate sliding surfaces can not be avoided. Furthermore, a good thermal conductivity of the localized plate is admittedly a suitable means (in connection with other measures), in order to prevent the solidification of the melt resp. to guarantee the spontaneous outflow when opening the closure. Nevertheless, at a distance from the said opening, the temperature of the plate sliding surface must necessarily be lower than the solidification temperature of the melt, otherwise the tightness of the closure would be compromised.

The task to be solved with the invention consists in guaranteeing the tightness along the sliding surfaces during a sliding closure during a large number of sliding movements and thereby enabling extended operating periods without changing the closure bodies. In this context, it should be mentioned that under certain operating conditions, especially when casting light metal melts, the wear at the flow openings of the closing plates is small. In such cases, in practice, the condition of the sliding sealing surfaces determines the length of use of the plates.

This object is solved according to the invention by means of a sealing device which is formed in the manner specified in claim 1.

Because the invention guarantees a tight closure during several thousand to over 10,000 slide operations with the same closing bodies, new areas of use for the sliding closure are opened up. Sa is made possible e.g. a continuous operation in melting, hot holding or casting furnaces during standing melting and the use in continued casting of separated, measured melting amounts in die casting.

In connection with the invention it should be reminded that the seal along the sliding surfaces of the closure body, starting from the stationary flow opening, must be guaranteed both versatile against the edge of the sliding surface and also - in the closing position of the movable closure body - against its flow opening, i.e. in the direction of movement or in the direction of the "closing grooves". With regard to the requirement mentioned above in second place, it is somewhat surprising, since according to the invention depressions or "grooves" formed by the wear are included in the sealing device. Intended use of wear and abrasion is also completely contrary to the common notion of "lubrication", which is precisely aimed at avoiding wear and reduction of friction (this of course does not exclude that wear-resistant materials may also have favorable sliding properties , which on the total sliding surface results in low friction).

According to the invention, the occurrence of wear residues in a mixture with metal particles is decisive for a lasting tightness during continued operation of the closure.

Although it is not possible to state in general and in summary which concrete pairs of materials lead to the goal, this can - thanks to the invention, be ascertained from case to case with relatively simple attempts.

One can mainly imagine the mode of operation of the said mixture so that the presence of abrasive particles prevents the build-up of continuous metal bodies between the sliding surfaces, which on solidification as "metal tongues" or "plates" would lead to rapid destruction of the closure bodies. The mixture shows a very small strength, but there is still a certain cohesion with the particles, whereby a "rinsing out" is prevented and the groove-shaped depressions remain constantly filled by the mixture. Incidentally, the sealing effect is apparently not dependent on whether the metal particles remain melt-liquid in the mixture or (temporarily) solidify. Only then after a series of maneuvers e.g. the melting vessel is emptied and the temperature at the sealing sliding surfaces drops considerably below the solidification temperature of the melt, later, after refilling of the melt, the sealing can be continued without any problems.

The invention is equally applicable to linear sliding closures as to rotary and pivot closures. 10 15 120 25 30 45 & _8ÛÛ 4 The rotational movement can then be of alternating direction (analogous to the linear connection) or always in the same direction. The closure of the furnace or the melting vessel can also be mounted with a horizontal, inclined or vertical position of the sliding surfaces.

Various exemplary embodiments of the invention are described in more detail below in connection with the drawing. Fig. 1 shows essential parts of a linear sliding closure mounted on a melting vessel in longitudinal section, Fig. 2 shows a view of the sliding surface of the stationary closing plate (partially broken away) of the closure according to Fig. 1, Fig. 3 shows a corresponding view of the stationary closure plate of a pivot closure closure, §¿g¿_g a section along the line IV-IV in Fig. 2 through a portion of the stationary and movable closure plate in high magnification, Fig. 5 a microscopic grinding photograph of the slope of wear and metal particles in section along the line VV in Fig. 3, i.e. perpendicular to the direction of movement (magnification approx. 150 times linear), and Lig¿_§ a similar grinding photograph in section along the line VI-VI in Fig. 3, ie. in the direction of movement (magnification approx. 165 times linear). in the embodiment according to: Fig. 1, only the two closure bodies - here in the form of two flat plates 12 and 14 - are drawn with solid lines, while further parts of the sliding closure 10 as well as parts of the melting vessel, to which the closure 10 is mounted, only dash points are indicated. The melting vessel 1 contains a metal melt 3, for example an aluminum melt, and has a casting opening 2, which leads to the sliding closure 10. The fixed base plate 12 of the closure is the retainer in a base plate 16 attached to the melting vessel 1 and has a continuous flow opening. 13. With the bottom plate 12 or with its sliding surface 9, the movable sliding plate 14 of the closure stands in sliding contact, ie. the slide plate, together with the slide 18 receiving it, is displaceable back and forth in the direction of the arrow P along the sliding surface 9. The flow opening 15 of the slide plate is thereby conveyed in a known manner either with the flow opening 13 of the bottom plate 12 to cover against this (closing mode). At the flow-through opening 15, a casting sleeve 17 inserted in the slide 18 can connect in a known manner.

It is not necessary to show in detail the further construction of the closure according to Fig. 1, since this is not required for understanding the invention. For the sake of completeness only, reference is made to Swiss patent application 3255 / 81-5 or German patent application P 32 08 101.4, Swiss patent specification 523 730 and German patent specification 19 51 447 as examples for linear slide closures and to European published patent application 0 040 692 or German Offenlegungsschrift 30 13 975 as an example for rotary fire connections. It should nevertheless be emphasized that the sealing device according to the invention can not only be used with flat sealing bodies with a flat sliding surface such as e.g. according to Fig. 1, but in principle also with closing bodies of another design with e.g. cylindrical, conical or spherical sealing surface.

The tightness of the closure 10 is given during its commissioning in a known manner in that the sliding surfaces of both plates 12, 14 are accurately flat and that the plates are permanently clamped perpendicular to the sliding surfaces. In order to still guarantee the tightness not only for a few maneuvers but according to the invention also for continued operation with thousands of maneuvers, one closing body, in the present case the stationary bottom plate 12, is made of a wearable material at least along its sliding surface 9, while the second closure body, here the displaceable plate 14, consists of wear-resistant material. The wear resistance of the material is shown in the wear results at the sliding surface 9 of the plate 12, which are shown in more detail in Figs. 2 and 4 and are explained below.

Then the closure with new plates 12, 14 and during filling with melt 3 according to fig. 1 continues to be operated, 1454 son 10 15 220 25 30 35 40 6 ie. the slide plate is displaced back and forth in relation to the bottom plate in the direction of the arrow P, a "wear pattern" occurs very soon at the sliding surface 9 of the wear plate 12, as can be seen from fig. 2. It is formed in a surface area extending from the flow-through bore 13 outwards with approximately the stroke on both sides (the bore 15 in the closed-position position is indicated in Fig. 2), more or less randomly arranged and shaped groove-shaped depressions 19, which mainly run in the direction of wear. The width of the said surface area corresponds approximately to the diameter of the bore 13 (even when this is, for example, larger than that of the bore 15), and it can also according to fig. 2 extend slightly beyond 2 this diameter._Fig. 4 shows in strong magnification this typical wear image in cross section. As can be seen from the figure, the said depressions or "wear grooves" 19 are still not empty, but are initially filled with a mixture of material 20, which arises during the closing operation between the plates 12 and 14 and is stored in the depressions 19. It is a mixture of wear particles from the wearable plate 12 and small particles, for example drops of the melt 3, which are retracted between the plates during the sliding movement. As can be seen from Fig. 4, as expected, the sliding surface of the wear-resistant plate 14 remains practically flat or without wear.

The results and processes described above have the consequence that the closure remains operational and securely tight during a very large number of maneuvers. Thus, at the beginning of the operation, by operating the closure during filling with melt in the manner described, a sealing device is formed between the closure bodies 12 and 14. It has been found that the wear or depth of the grooves 19 does not constantly increase, but possibly after a few hundred maneuvers practically remain constant. The observed groove depth goes from a few tenths of a millimeter to over a millimeter. Even with the reverse arrangement of the closing bodies - wear-resistant body stationary and wearable body displaceable - the formation of the described sealing device is similarly possible in principle. Admittedly, this can have certain disadvantages in other respects, e.g. when bi '10 15 20 25 30 35 40 454 800 the wear-resistant sliding surface is in long-term contact with the standing melt 3.

It is surprising that the described "wear pattern" with embedded material mixture at the wearable sliding surface occurs only in the mentioned surface area shown in Fig. 2, and not in the surrounding areas of the sliding surface 9. This means (as also the composition of the sliding surface). 20) shows that the process is bound to the presence of melt. It is to be assumed that during the relative displacement of the closing bodies small amounts of melt are drawn in between the sliding surfaces and then, possibly after their solidification, causes the wear. The phenomenon could also be observed with such materials which in themselves are only slightly wetted by the melt (eg different types of graphite). Although the processes in the interior of the "wear grooves" 19 are not accessible for direct observation, it is assumed that the local composition of the mixture 20 constantly changes when the closure is operated. Admittedly, the particles of the mixture, at least in the cooled state, show a certain cohesion. When the closure is stopped after prolonged operation and the closure plates are removed from each other, the mixture suitably remains easily adhered to the surface of the wear-resistant plate 14.

Of course, it is not necessary for one of the closure bodies to consist consistently of wearable material, but it is sufficient if this property is present at least at its sliding surface. The current closure body or closure plate 12 can e.g. in thickness be composed of two or more layers of different materials. In this way, sealing bodies can be produced which, in addition to the required wear and tear at the sliding surface, have certain advantageous combinations of material properties, for example with respect to thermal conductivity, flexural stiffness, hardness, etc.

Pig. Fig. 3 shows, in contrast to Fig. 2, the view of the wearable sliding surface of the stationary closing plate 22 of a rotary slide closure. Its eccentrically arranged through-flow opening is denoted by 23 and the position of the through-flow opening of the movable, wear-resistant closure plate (not shown) in its closed position is indicated by a dotted point at 25. After further operation of this closure by 10 15 20 25 _30 35 40 454 800 8, rotation of the movable closing plate in the direction of the arrow R produces the "wear pattern" shown in Fig. 3, i.e. substantially circular, concentric, groove-shaped depressions 19 'appear in the wearable sliding surface of the closure plate 22. If, on the other hand, the rotary closure, which is also known, is opened and closed by partial rotations with varying direction of rotation, the depressions 19 'would only extend over a corresponding circular arc of limited length. Incidentally, the above embodiments according to Figs. 1, 2 and 4 apply to the formation and the properties of the sealing device and in particular the material mixture stored in the wear grooves in the same way also to the embodiment according to Fig. 3.

The microscopic wear images according to Figs. 5 and 6 give an idea of the structure of the mixture 20 forming a component of the sealing device (Fig. 4).

After a sealing closure according to the example according to Fig. 3 of the sealing device has been formed in the manner described and the closure has been in operation for a longer period of time, the closure would be stopped and dismantled. When separating the rotatable from the stationary closure plate, most of the mixture stored in the recesses 19 'would adhere to the sliding surface of the rotatable plate.

This sliding surface of the rotatable plate forms the lower edge in Figs. 5 and 6 and is there denoted by 14 '. The surface 14 'of the mixture was then overmolded with a curing casting resin (G in Figs. 5 and 6), and after curing of this the preparation was cut partly along the line VV and partly along the line VI-VI in Fig. 3, i.e. once across the moving and in the second case tangentially with a certain wear groove 19 ', i.e. at the current point of contact for the section line in the direction of maneuvering motion.

At the relevant locations, the grinding images according to Fig. 5 and Fig. 6 were then taken. In both images, the embedded metal particles M are visible as light, practically white spots. The wear particles A mixed with metal particles appear gray. The more or less large dimples to the black spots H, on the other hand, are to be interpreted as cavities in the mixture or as irregularities in the grinding plane, which arose during the preparation of the preparation. 'ü p.

IN! 10 15 20 25 30 35 40 454 800 Fig. 6 clearly shows the direction of movement during the closing operation in comparison with Fig. 5. Both figures show a rather irregular mixture, in which case it is nevertheless essential that no larger "metal lumps" are formed, but that the metal parts are always separated by intermediate-bearing wear parts. Some concrete materials or material pairs for closing bodies are given below as examples, such as those which are advantageously used in the manufacture of the described sealing device. It is understood that these statements may not be complete. The selection must from case to case be made from materials which, in relation to the actual melt at the given temperature, are sufficiently durable. The decisive point of view for suitability is then whether in the selection experiments in the presence of melt the described wear results and the mixture can be obtained, which then enables the formation of the sealing device and thus the excellent lasting operation for the closure. For example, graphite or material mixtures with a high proportion of graphite or other materials with a similar, characteristic "disc structure" are suitable.

Example 1: An electrographite closure plate (99% graphite content, 18 vol.% Open porosity) was used as a wearable, stationary plate in connection with a wear-resistant zirconia oxide plate (95% ZrO 2) in a linear slide closure attached to a gutter . By continuing to operate the closure, measured amounts of an aluminum casting alloy (G-AlSi9Mg according to DIN 1725, with 9% Si and 0.3% Mg) were cast at a temperature of approximately 750 ° C.

In this way, the sealing device was formed in the manner described.

After approximately 3000 operating strokes without disturbance and with a trouble-free tightness of the closure, the casting operation was interrupted, and the closure plates were dismantled to examine the sealing device. In doing so, it turned out that the tiles had been usable without risk.

Example 2: A rotary slide closure was provided with a wearable, stationary closing plate of hot-pressed boron nitride BN with hexagonal lattice structure and a rotatable plate of ZrO 2 (same material as Example 1). In an experimental device a pure aluminum melt (99.5% Al) was cast 10 at 15 ° C at 750 ° C with continued opening and closing of the closure. After 965 interference-free maneuvers (twists), during which the described sealing device was obtained, the experiment was stopped.

Example 3: The same closure as in Example Z was installed under the same test device and with the same melt, but with a different plate equipment in a long-term test. In this case, a stationary plate of carbon with a high proportion of graphite (over 92% electrographite) was combined with a wear-resistant rotating plate of material with a high aluminum content (90% Al2O3, 8% SiO2). The experimental series included no less than 10,550 maneuvers, ie. castings with shorter and longer interruptions and associated cooling of the closing plates. The subsequent examination showed that the plates or sealing device was further functional.

Example 4: A rotary slide closure was installed as a drain closure at a melt and heat holding furnace for pure aluminum (approx. 750 ° C). The closure was provided with a stationary plate of electrographite (99% graphite, 14% vol. Open porosity) and a rotatable plate of aluminum titanate. Al2TiO5 and the operation were characterized by frequent drains of relatively small amounts of melt. This was achieved during about three and a half days about 800 closure operations at full tightness.The subsequent examination gave that the plates or their sealing device was further operable.With closure plates of the same material was achieved in a rotary slide closure mounted in an experimental device to and with approximately 6400 maneuvers without interference. i .1: I III

Claims (7)

fJ 10 15 20 25 30 1, 454 800 Beisnikrax Sliding closure light metal melts, with two preferably flat ones characterized in that the sealing body (14, 14 ') which can be cast for casting metal, especially sealingly against each other, is durable against the other closing body (12, 22). at least at its sliding surface (9) is relatively wearable in such a way that between the closing bodies (12, 22; 14, 14 ') during sliding contact movement between the closing bodies (12, 22; 14, 14') and during supply with the molten metal it is formed a sealing amount (20) of wear particles (A) and metal particles (M). Sliding closure n a d according to claim 1, characterized in that the wearable closure body (12, 22) is fixed and the wear-resistant closure crepe (14) is displaceable. Sliding closure characterized in that according to claim 1 or 2, the wearable closure body (12, 22) has a predominantly bead of graphite. The sliding closure of a den according to claim 1 or 2, characterized in that the sealing body (12, 22) consists predominantly of boron nitride having a hexagonal lattice structure. 5. Sliding closure t e c k n a d that the 14 ') has a high aluminum content. 6. Sliding closure t e c k n a d 14 ') predominantly consists of Sliding closure characterized in that it consists in that it 14 ') predominantly consists according to claim 1 or 2, has the most durable closure body (14, according to claim 1 or 2), has - wear-resistant closure body (14, zirconia) according to claim 1 or 2, feel - alite fixed body (14, aluminum titanate.