FI78973B - ANSLUTNINGSKONSTRUKTION FOER FAESTANDE AV EN GLIDRING TILL EN MONTERINGSDEL. - Google Patents

Abstract

The invention relates to a joint for fastening a mounting part (12) made of a plastic material to a slide ring (11) made of a ceramic material. The joint comprises a ring fastener (13) made of metal which provides a shrinkage grip on the axial outer surface (15) of the slide ring (11), and on the axial outer contact surface (16) of the mounting part (12) in such a way that the axial wall of the recess formed in the mounting part (12) to receive the slide ring (11) bears closely against the axial outer surface of the slide ring (11) within the area (14) of the bottom end of the space. A fixed ring (11), eg attached to a housing, is engaged by a rotary ring (11), eg attached to a shaft, to provide a ceramic seal against leakage of a fluid. <IMAGE>

Description

1 78973

Connecting structure for attaching the slip ring to the mounting part.

The invention relates to a connecting structure for fastening a sliding ring to a mounting part, which connecting structure comprises a mounting part made of plastic material and a ring of ceramic material to be fastened to the space formed therein.

The incorporation of ceramic materials into the plastic material is very problematic because the the coefficients of thermal expansion of the materials 10 differ considerably.

The problem is further aggravated by the fact that the other properties of the above-mentioned materials also differ greatly from each other. Both materials have properties that place restrictions on the use of certain joining solutions. As an example, gluing is prevented by different thermal expansion coefficients, as well as poor gluability of certain plastics, difficult machinability of the threaded ceramic material and poor strength of the plastic, welding failed * because the melting temperatures of the materials are completely different, etc.

20 It is necessary to find a usable connection solution in spite of very different material properties, as the above-mentioned materials can be successfully used in a complementary manner under the same conditions of use. One example is the connection between PTFE and silicon carbide in a mechanical seal. The chemical resistance of these materials is good, but the wear resistance of PTFE is poor and the formability of silicon carbide is difficult and expensive, so it is sensible and necessary in practice to join these materials together so that the joint is pressure-resistant and somewhat force-transmitting.

In practice, the joints of the above-mentioned ceramic material and plastic material have often not had to be realized, because the ceramic materials have not yet been ready for practical applications. Recent 2,78973 strong product developments in ceramic materials have made it possible to apply them to new areas and otherwise improved their usability.

Until now, connections of the above-mentioned type have been made, for example, by making a groove in the mounting part made of plastic material, into which a sliding ring made of ceramic material is fitted. Em. the groove is formed so that a linear pressure contact is formed on the inner circumference of the sliding ring, which seals the joint 10 between the parts.

The disadvantage of the above-mentioned connection method is that a sliding ring made of ceramic material has to be machined on both the inner and outer circumference. Because the processing of ceramic materials is slow and expensive, 15 the cost becomes considerably high. In particular, it should be noted that machining the inner circumference is difficult. A further disadvantage is that the ring tends to protrude easily out of the groove as the temperature rises. In addition, it should be noted that the torque transmission capacity 20 of the above solution is weak, since the coefficient of friction between the plastic material and the ceramic material is small.

The object of the invention is to provide a connecting structure by means of which the disadvantages of the prior art can be eliminated. This is achieved by a connecting structure according to the invention, characterized by a fastening ring made of metal material, which is adapted to press against the axial outer surface of the slip ring on the one hand and against the axial counter surface 30 in the region of the head tightly against the axial outer surface of the slip ring.

The advantage of the invention is above all that the manufacturing costs remain relatively low. The reason for this is that the ceramic part does not need to be machined 3 78973, for example from the inner circumference at all. A further advantage is that the torque transmission capacity of the connecting structure according to the invention is remarkably good compared to previously known solutions.

The invention will be elucidated by means of the examples described in the following drawing, in which Fig. 1 shows in principle a sectional view of a connection between a ceramic slip ring and a mounting part according to the prior art, Fig. 2 shows in principle a sectional view of a plant structure according to the invention; a sectional view of a slip ring seal utilizing the plant structure of Figure 2.

Figure 1 shows in principle a sectional view of an example of a previously known solution for attaching a slip ring 20 to a mounting part, for example a sealing ring. Figure 1 shows only half of the cross section of the slip ring. However, it is clear that in reality the structure is similar on both sides of the axis of symmetry marked with a dashed line in Figure 1.

The ceramic slip ring is indicated in Fig. 1 by reference numeral 1 and the mounting part made of plastic material is denoted by reference number 2. A groove 5 for the slip ring 1 is machined in the mounting part 2 so that compression 30 occurs when the slip ring 1 is pressed into place. .

The tightness of the joint shown above is not good because the surface area of the sealing surface 3 is very small. In practice, a line-like contact is created between the slip ring 1 and the mounting part 2. There can be no large compression on the outer circumference of the slip ring indicated by reference numeral 35 4, because if this were the case, the slip ring would easily tend to rise 4 78973 out of the groove 5.

When making the connection in the above-mentioned manner, the ceramic slip ring 1 has to be machined from both the inner and outer circumference. Because the processing of ceramic materials is 5 very slow and expensive, the cost becomes considerably high. In particular, it is difficult to machine the inner diameter, and in the solution described above, a good surface has to be machined on the inner circumference 6 of the slip ring 1 in order to achieve the necessary tightness at point 3.

A further disadvantage of the above-mentioned known solution is that when the body heats up, the high coefficient of thermal expansion of the plastic material may cause the sliding ring 1 to protrude out of the groove 5, since the mounting part 2 also expands in the axial direction.

The torque transfer capacity of the solution M according to Fig. 1 between the slip ring 1 and the mounting part 2 is poor because the holding area is small and the plastic and ceramic materials are slippery, i.e. there is a low coefficient of friction between the slip ring 1 and the mounting part 2.

Figure 2 is a schematic sectional view of a connecting structure according to the invention. Figure 2 is drawn in the same way as Figure 1, i.e. only half of the structure is drawn.

In Fig. 2, reference numeral 11 shows a slip ring made of ceramic material. The mounting part made of plastic material is in turn denoted by reference numeral 12. Reference numeral 13 denotes a fastening ring made of metallic material. The use of metallic material is possible because the connecting structure can be designed so that a corrosively aggressive substance, e.g. a liquid, is on the inner diameter side of the slip ring 11 and the mounting part 12.

The connecting structure according to the invention can be implemented as follows. The ceramic slip ring 11 is placed in a mounting part 12 made of plastic-35 material in a machined space, for example in a recess, which is particularly evident in Fig. 2. The fastening ring 13 is fastened by a shrink joint to the slip ring 11 and the mounting part 12 as shown in Fig. 2. The fastening ring 13 is dimensioned so that a suitable pressure is generated between the axial outer surface of the fastening ring 13 and the sliding ring 5 11. Em. the clamping point is indicated by reference numeral 15. The clamping ring 13 is further dimensioned so that the clamping ring presses against the axial abutment surface of the mounting portion 12 at 16 so that the axial wall of the space formed in the mounting portion 10 12 presses tightly against the outer end 14 The sealing of the joint thus takes place in the region 14 so that the fastening ring 13 does not come into contact with a possible corrosively aggressive substance.

The fastening ring 13 is further machined with a groove 17, by means of which the sliding ring 11 and the fastening ring 13 remain attached to the mounting part 12. Em. the principle of operation of the groove 17 is clearly shown in Fig. 2. The idea of the groove 17 is that when the fastening ring 13 is pressed against the mounting part 12, a soft plastic material exudes into the groove 17 as shown in the part of Fig. 2 describing the above detail. Em. Muolen provides a way of keeping the direction of the joint.

The joint according to Figure 2 tightens in use as the parts 25 become slightly warmer as the plastic material expands

when heated more than the materials of other parts. Thus, the compression at points 14 and 16 increases and the tightness of the joint improves. At the same time, more plastic material exudes into the groove 17, improving the adhesion of the slip ring and the fastening-30 ring in the mounting part 12. The torque M

the displacement capacity is also completely sufficient already in the assembly dimension, because the force can be transmitted from the slip ring 11 and the retaining ring 13 to the mounting part 12 through both point 14 and point 16. The torque transfer capacity also improves as the mounting part 12 35 expands. The cooling of the parts to a temperature lower than the assembly temperature does not cause any problems, because then the mounting part 12 presses even more tightly against the slip ring 11. However, as a result of the correct dimensioning, the mounting part 12 does not become detached from the fastening ring 13. The adhesion of the slip ring 11 and the fastening ring 13 to each other is not a problem, as it can be controlled by normal mechanical dimensioning.

The connecting structure according to the invention is advantageous to implement in practice, because the mechanical slip ring 11, which is difficult to machine, has to undergo very little machining, e.g. the inner circumference does not need to be machined at all. The clamping ring 13 must, of course, be machined to exact dimensions, but this is not a problem with modern machine tools, as it is in practice a simple part. The mounting part 15 of plastic material, on the other hand, is easy to machine.

As already stated above, the torque transfer capacity of the plant structure according to the invention is good. However, the torque transmission capacity can be further improved by using, for example, a pin or 20 wedges between the mounting part 12 and the fastening part 13.

The assembly of the connecting structure according to the invention is in practice a simple event. The fastening part 13 is heated in an oven and the sliding ring 11 and the mounting part 12 can, if necessary, be cooled accordingly, for example in a freezer. The fastening part 13 is installed in place according to Fig. 12 and the temperatures are allowed to stabilize, whereby the parts 11, 12 and 13 adhere to each other.

Figure 3 shows in principle one complete embodiment of the invention, in which the sliding ring seal 30 has the fastening of both the sealing ring T and the sliding ring 31, 32 of the counter ring V implemented in accordance with the invention. The sealing ring T (mounting part is indicated in the figure by reference numeral 33 and the counter ring V mounting part by reference numeral 34, respectively. The fixing rings are indicated in Fig. 3 by reference numerals 37, 38. In the solution 7 78973 in Fig. 3, the sealing ring T is fixed to the rotating shaft 35 should be very tight at point 14 (Fig. 2), as there is a pressurized liquid in the state S.

5 The connecting structure must also transfer the torque caused by the sliding surfaces of the sliding rings 31, 32 sliding against each other. The pressure in the state S also reaches behind the slip rings, which is why the locking in the axial direction N (Fig. 2) must be strong enough, e.g. as described above.

The above embodiment is in no way intended to limit the invention, but the invention can be modified completely freely within the scope of the claims. Thus, it is clear that the connecting structure 15 or parts thereof according to the invention do not necessarily have to be exactly as shown in the figures, but other solutions can also be used, etc.

Claims (2)

8,78973 A connecting structure for attaching a slip ring to a mounting portion, the connecting structure comprising a mounting portion (12,33,34) made of a plastic material and a ceramic material ring (11,31,32) to be attached to the space formed thereon, characterized by a mounting ring (13) made of a metal material. 37,38) adapted to press 10 on the one hand against the axial outer surface (15) of the slip ring (11,31,32) and on the other hand against the axial abutment surface (16) of the mounting part (12,33,34) so that the mounting part (12,33 , 34) the axial wall of the formed space presses tightly against the axial outer surface of the sliding ring (11,31,32) in the region (14) of the space-side end 15 of the space. Connecting structure according to Claim 1, characterized in that a groove (17) is formed in the surface 20 which presses against the axial abutment surface (16) of the mounting part of the fastening ring (13, 37, 38).