EP0374407B1 - Assembling method - Google Patents

Description

The invention relates to a method for determining drive or coupling elements - such as cams, gears, crank webs - or of bearing elements - such as plain bearing bushes or complete roller bearings - on pipes or pipe sections by hydraulically expanding the pipe in the area of the respective elements beyond the elastic limit against one elastic prestressing in the respective elements by means of a pressure medium probe, which has effective sections delimited by seals in association with the elements which are connected to a pressure medium generator via a first bore system of the probe, and with intermediate sections between individual active sections which are connected to a second bore system of the Stand probe, as well as with end sections each adjoining the outermost knitting sections, the knitting sections with the pipe knitting areas and the intermediate sections with the pipe intermediate sections, and the end sections with the pipe endber Form oak.

From DE-A-37 26 083 (Balcke-Dürr) a pressure medium probe is known which has two mutually independent bore systems, one of which is connected to a pressure medium generator to act upon the effective areas and the second is connected to the intermediate sections of the leak medium discharge should serve, especially if some of the seals fail. The procedure that can be carried out with this is due to the pressure build-up marked in the effective areas until the elastic limit of the affected pipe sections is exceeded and the subsequent pressure reduction. Correspondingly, pressure generators with an output are used which are connected directly to the first drilling system of the pressure medium probe.

The main problem with the known method is the lack of operational reliability of the seals, in particular since the pressures required will continue to increase in the case of increasingly larger shaft types which are to be produced by this method. The invention has for its object to provide a method that reduces the risk of seal failure and increases the possible service life of the seals. Furthermore, a pressure medium probe suitable for carrying out the method and a suitable pressure generator which can be connected to such a probe are to be provided for carrying out the method.

The solution to this is that the effective areas are subjected to a high effective pressure suitable for deforming the tube beyond the elastic limit, and that the intermediate areas and the end areas, at least in sections on both sides of the effective areas, at least while the high effective pressure is present, with a pressure above the ambient pressure and are applied under the lower counterpressure required for the deformation beyond the elastic limit. With this method according to the invention, significantly increased differential pressures can be generated without the type of seals used - generally standard ring seals - having to be fundamentally modified, since their Failure and wear are primarily determined by the pressure difference to be sealed, while they are relatively insensitive to an increase in the absolute pressure level. The inventive generation of a back pressure outside the effective areas, which does not permanently impair the properties of the tubular body exposed there, prevents the seals from excessively entering the sealing gap and thus significantly increases the service life of the seals and at the same time opens up the possibility of a further increase in pressure. It is particularly important to apply the counterpressure to the seals when the pressure is reduced after the pipe widening, since in this phase there is a risk that the seal will be partially pinched in the sealing gap and will be mechanically damaged when the pressure medium probe is pulled out of the pipe body.

When using a simple pressure medium generator that can only build up the pressure uncontrolled, a pressure below the differential pressure is first built up to build up the pressure in the effective areas and then the pressure builds up in the effective areas and the back pressure in the intermediate areas is built up and end areas, the pressure in the effective areas always being higher than in the intermediate and end areas until the desired back pressure is reached and the pressure difference must remain below the design limit of the seals, and then the pressure build-up in the effective areas takes place to the desired level Effective pressure instead, the higher pressure in the effective areas always ensuring that the seals are in contact, while to reduce the pressure after building up and maintaining the effective pressure, the pressure in the effective areas is first at an intermediate pressure below the counterpressure is reduced to allow the seals to be relieved and spring back, and then the further pressure reduction in the effective areas and the pressure reduction in the counterpressure in the intermediate areas and end areas take place together.

Depending on the design of the pressure medium probe, the volumes of the intermediate and end areas connected to the second bore system are relatively large, so that it is a good idea to continue filling the cavities with the pressure medium with a low filling pressure below the counterpressure. This requires a pressure medium generator with the appropriate control option. In a further embodiment, the method step mentioned is to be extended analogously to the filling of the effective areas before the effective pressure is given up. Depending on the behavior of the seals, the filling pressure mentioned is to be set so that it brings them to the sealing contact on the pipe, so that no uncontrolled deformations of the seals take place when the active and counterpressure are subsequently given up.

The pressure reduction in the effective areas on the one hand and the end and intermediate areas on the other hand should preferably be carried out in the reverse order of how the pressure is built up, whereby the objective here must also be to keep the pressure differences effective at the seals as low as possible and to solve them with the reverse pressure difference of the seals.

After a favorable modification, the above-mentioned filling pressure is already during the insertion of the pressure medium probe and while the pressure medium probe is being pulled applied from the tubular body so that liquid flows around the seals under low pressure. This creates a desired friction-reducing lubricating effect for the seals against the rough inner wall of the tubular body.

A pressure medium probe according to the invention for carrying out the above-mentioned methods is characterized in that further seals for the formation of pressurizable end sections are arranged at a distance outside the outer active sections delimited by seals, that the end sections have the same system of longitudinal channels and associated radial bores how the intermediate sections are connected and that both drilling systems can be connected separately with pressure generating means. With a pressure medium probe constructed in this way, it is possible, as explained above, to generate the required counterpressure in the intermediate and end regions before or during the application of the differential pressure in the active regions.

Another pressure medium probe according to the invention is characterized in that the seals of the active sections arranged in pairs are framed on both sides by at least one counterpressure section delimited by seals arranged at a distance, which are connected in pairs to the second system of longitudinal channels and radial bores, and in that both drilling systems separately seal with pressure generating means are connectable. According to the invention, each active section is assigned separate adjacent sections in which a counterpressure can be applied. Depending on the design of the probe, this arrangement can be advantageous since the volumes to be acted upon by the counterpressure are significantly smaller can be held. In contrast, the need for a larger number of seals is eliminated. The design referred to here is advantageous in the case of probes with particularly pronounced sealing sections of larger diameter.

The two basic configurations of the probe mentioned above can be combined in a favorable manner in such a way that a third bore system of longitudinal channels and radial bores is provided, the three existing systems then being acted upon with different pressure levels, so that a two-stage pressure difference is particularly high for the task Printing in the effective areas becomes possible. The intermediate pressure areas immediately adjacent to the effective areas can be kept so short that they still lie within the elements to be defined and the pressure effective in them deforms the tube beyond the elastic limit.

Pressure generators according to the invention for carrying out the method according to the invention and for connection to the pressure medium probes mentioned are characterized in that a single working or pressure converter piston can act on at least two pressure medium outlets with different pressures during the working stroke, in particular the working piston can be designed as a differential piston and by the connection certain dead spaces the various required pressure profiles can be generated.

• Fig. 1 zeigt eine Druckmittelsonde mit zwei Bohrungssystemen im Längs- und Querschnitt
• Fig. 2 zeigt eine Druckmittelsonde mit drei Bohrungssystemen im Längs- und Querschnitt.

Preferred exemplary embodiments of probes according to the invention are shown in the drawings.

• Fig. 1 shows a pressure medium probe with two bore systems in longitudinal and cross-section
• Fig. 2 shows a pressure medium probe with three bore systems in longitudinal and cross-section.

1 shows a probe base body 1 which ends in a probe head 2 and is pushed onto the two sleeves 3, 4, which are soldered to the base body, for example. The base body consists of an integral tube 5 connected to the probe head and an outer tube 6. On the sleeves 7, 8 effective areas a₁, a₂ are defined by pairs of seals. An intermediate area b lies between the effective areas. A further seal 11 is arranged on the probe head and defines an end region c with the seal 10. The effective areas are connected by radial bores 12, 13 to a central pressure medium supply bore 14 in the probe base body 1, which completely penetrates the latter and is closed in the probe head 2 by means of a plug 15. The intermediate areas b₁, b₂ are connected via radial bores 16, 17 to a longitudinal channel 18 formed as a groove in the inner tube 5; the end section c is connected by means of a further radial bore 19 to precisely this longitudinal channel, which is closed at the end by the probe head 2. This second bore system serves to build up the back pressure in the entire intermediate areas b and end areas c.

In FIG. 2, a sleeve 22 is pushed onto a probe body 21 in a one-piece construction, which sleeve can, for example, be glued, shrunk or soldered onto the tubular body. The sleeve carries paired seals 23, 24 which define an effective range a₃. The effective area is connected to a central pressure medium channel 26 via a radial bore 25 running perpendicular to the drawing. Each immediately adjacent to the seals 23, 24 are further seals 27, 28 on the sleeve 22, which define d₁, d₂ with the aforementioned counter or intermediate pressure sections. These are connected via radial bores 29, 30 to a longitudinal channel 31 in the probe base body 21, via which a back pressure is to be applied if no further bores are provided in the probe or an intermediate pressure if the probe continues to have the details described below. These consist of a third system of radial bores 32, which are optionally subjected to a back pressure for the intermediate and end regions via a third longitudinal channel 33.

Reference symbol list

1

Probe body

2nd

Probe head

3rd

Sleeve

4th

Sleeve

5

Inner tube

6

Outer tube

7

poetry

8th

poetry

9

poetry

10th

poetry

11

poetry

12

Radial bore

13

Radial bore

14

Longitudinal channel

15

Plug

16

Radial bore

17th

Radial bore

18th

Longitudinal groove

19th

Radial bore

20th

21

Probe body

22

Sleeve

23

poetry

24th

poetry

25th

Radial bore

26

Longitudinal channel

27th

poetry

28

poetry

29

Radial bore

30th

Radial bore

31

Longitudinal channel

32

Radial bore

33

Longitudinal channel

a₁, a₂, a₃

Effective range

b₁, b₂

Intermediate area

c

End area

d₁, d₂

Back pressure or intermediate area

Claims (15)

1. A method of assembling driving or coupling elements such as cams, gears and crank webs, or of assembling bearing elements such as friction bearing bushes or complete rolling contact bearings on tubes or tube portions by hydraulically expanding the tube in the region of the respective elements (3, 4) beyond the limit of elasticity against an elastic pretension in the respective elements (3, 4) by means of a pressure agent mandrel comprising operating portions which are limited by seals (7 - 11) and associated with the elements (3, 4), and which, via a first system of bores (12 - 15) of the mandrel, are connected to a pressure agent generator, and further comprising intermediate portions between the individual operating portions which are connected to a second system of bores (16 - 19) of the mandrel, as well as end portions (c) adjoining the outermost operating portions, the operating portions, together with the tube, forming operating regions (a₁, a₂), the intermediate portions, together with the tube, forming intermediate regions (b₁, b₂) and the end portions, together with the tube, forming end regions (c),
characterised in
that the operating regions (a₁, a₂) are subjected to a high operating pressure suitable for deforming the tube beyond the limit of elasticity and that, during the application of the high operating pressure, the intermediate regions (b₁, b₂) and the end regions (c), at least in portions on both sides of the operating regions (a₁, a₂), are subjected to a lower counter pressure which is higher than the ambient-pressure and lower than the pressure required for deforming the tube beyond the limit of elasticity.

2. A method according to claim 1,
characterised in
that, for the purpose of a pressure build-up, there is first built up a pre-pressure for sealingly positioning the seals in the operating regions, which pre-pressure is lower than the operating pressure, that thereafter there takes place a further pressure build-up in the operating regions and a build-up of the counter pressure in the intermediate regions and end regions, with the pressure in the operating regions always being higher than in the intermediate and end regions, until the required counter pressure is reached, and that thereafter the operating pressure in the operating regions is built up further until the required level is reached.

3. A method according to claim 1 or 2,
characterised in
that prior to the build-up of the operating pressure in the operating regions and of the counter pressure in the intermediate and end regions, such regions are filled with a filling pressure which is lower than the counter pressure.

4. A method according to any one of claims 1 to 3,
characterised in
that for the purpose of decreasing the pressure after building up and holding the operating pressure, first the pressure in the operating regions is reduced to an intermediate pressure which is lower than the counter pressure to allow the seals to be released and spring back, and that thereafter a further pressure decrease in the operating regions and the decrease in the counter pressure in the intermediate and end regions take place simultaneously.

5. A method according to any one of claims 3 or 4,
characterised in
that by applying the filling pressure to the operating regions and/or the intermediate regions and end regions, the seals are deformed until they sealingly rest against the tube.

6. A method according to any one of claims 3 to 5,
characterised in
that even prior to inserting the mandrel and/or even while withdrawing the mandrel from the piece of tube, a pressure corresponding to the filling pressure is maintained for flushing purposes.

7. A pressure agent mandrel having at least two systems (12 - 19) which are independent of each other and which each comprise a longitudinal channel (14, 18) and radial bores (12, 13, 16, 17, 19) connected thereto, the radial bores (12, 13) of the one system ending in the operating portions limited by seals (7, 8, 9, 10) arranged in pairs and the radial bores (16, 17, 19) of the other system ending in the intermediate portions positioned therebetween,
characterised in
that outside each of the outer operating portions (a₂) limited by seals (10), there are arranged, at a distance, further seals (11) for forming pressurisable end portions (c), that the end portions (c) are connected to the same system of longitudinal channels (18) and radial bores (16, 17, 19) conntected thereto like the intermediate portions (b) and that both systems of bores (12 - 19) may be connected separately to pressure generating means.

8. A pressure agent mandrel having at least two systems which are independent of each other and which each comprise a longitudinal channel and radial bores connected thereto, the radial bores of the one system ending in the operating portions limited by seals arranged in pairs,
characterised in
that pairs of seals (23, 24) of the operating portions (a₃), on both sides, are each framed by at least one counter pressure portion (d) which portions are limited by spaced seals (27, 28 and which, while arranged in pairs, are connected to the second system of longitudinal channels (31) and radial bores (29, 30) and that both systems of bores may be connected separately to pressure generating means.

9. A mandrel according to claims 7 and 8,
characterised in
that there is provided a third independent system having a longitudinal channel (33) and radial bores (32) connected thereto, one system being connected to the portions immediately adjoining the operating portions and one system being connected to the remaining intermediate and end portions.

10. A pressure generator for being connected to a pressure agent mandrel according to any one of claims 8 to 9 for putting into effect a method according to any one of the preceding claims,
characterised in
that there is provided an operating or pressure converting piston which, during an operating stroke, pressurises at least two pressure agent exits with different maximum pressures.

11. A pressure generator according to claim 10,
characterised in
that the pressure curves up to the maximum pressure at the pressure agent exits are differently controllable in terms of time, especially temporarily adjustable in such a way that the same pressure differential exists between them.

12. A pressure generator according to any one of claims 9 to 11,
characterised in
that several pressure levels, especially variable in any sequence, may be set at each of the pressure agent exits.

13. A pressure generator according to any one of claims 9 to 12,
characterised in
that the operating or pressure converting piston is designed as a differential piston.

14. A pressure generator according to any one of claims 9 to 13,
characterised in
that the piston travel and thus the pressure agent quantities are adjustable and limitable.

15. A pressure generator according to any one of claims 9 to 14,
characterised in
that the pressure chambers pressurised by the operating or pressure converting piston may be connected to each other or to dead chambers by connectable guiding pipes.

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