CA2178740C

CA2178740C - Shrinking method

Info

Publication number: CA2178740C
Application number: CA002178740A
Authority: CA
Inventors: Richard Chene; Pascal Detable; Michel Andre
Original assignee: Etablissements Caillau SAS
Current assignee: Caillau SAS
Priority date: 1994-11-02
Filing date: 1995-11-02
Publication date: 2005-09-13
Anticipated expiration: 2015-11-02
Also published as: CZ292243B6; CZ189196A3; HU214856B; FR2726208B1; JP3179499B2; BR9506434A; TW305783B; WO1996014177A1; JPH09507795A; EP0737114A1; PL178959B1; CN1067303C; KR100264241B1; MX9602541A; FR2726208A1; CN1138302A; DE69526065D1; ES2173984T3; CA2178740A1; HUT75563A

Abstract

A method for shrinking a ring (14) fitted over the free end (10a) of a flexi ble tube (10) on a rigid tubular member (12). The method uses a shrinking die (16) with an axial cavity (18) including a splayed sect ion (18a) and a broad open end (20) whereat the diameter of the cavity is substantially the same as the greatest diameter (d) of said se ction. The shrinking die (16) is positioned so that at l east the broad end (20) of the cavity is located around the portion (14) to be shrunk while its narrow end is in front of the tube, and, whil e axially supporting one of the ring (14) and the shrinking die (16), both are mutuall y axially moved in a direction (F) extending from the fr ee end (10a) of the tube (10) towards the other end thereof.

Description

SHRINKING METHOD
The present invention is directed to a swaging method using a,swaging die for swaging a ring on a flexible hose.
It is known, e.g. in order to make a coupling device having a rigid tubular endpiece, that the free end of a flexible hose can be clamped between a ring and a rigid tubular element that are disposed coaxially, respectively outside and inside the hose.
For this purpose, it is necessary to perform a swaging operation to reduce the diameter of the ring.
In general terms, the present invention relates to a method of shrinking a ring engaged on the free end of a flexible hose, itself engaged on a rigid tubular element, said ring having at least a portion that is to be swaged and whose diameter is initially greater than that of the hose.
The method uses a swaging die provided with an axial cavity including a flared length that flares from a first end towards a second end, the cavity having an open large end where the diameter of said cavity is substantially equal to the diameter of said flared length at the second end thereof.
Axial swaging is commonly used for jobbing work on rigid tubes.
The patent granted in the United States under the 2S number 2 314 002 describes a method that attempts to use axial swaging to swage a ring that is engaged on .the free end of a flexible hose.
In that method, the swaging die is initially placed around the die and is then displaced over the ring towards the free end of the hose.
Because of the need to place the swaging die around the hose, the smallest diameter of the axial cavity is not less than the outside diameter of the hose. Since the ring is itself disposed around the hose, its inside diameter is also not less than the outside diameter of the hose. Consequently, .the effective reduction in diameter during swaging is never greater than the thickness of the ring.

As a result, the reduction in diameter runs the risk of being insufficient to ensure that the assembly comprising the hose, the ring, and the tubular element holds together reliably.
The only way of increasing the amplitude of swaging, i.e. of causing the reduction in diameter to be greater, consists in increasing the thickness of the ring, and that leads inevitably to an increase in materials costs and to an increase in the power required for swaging.
It is also known that radial swaging can be implemented by using a swaging tool that has a plurality of angular sectors that are movable relative to one another. That method is unsatisfactory insofar as it gives rise to defects in the appearance of the swaged portion which can go as far as longitudinal folds appearing because of the radial gaps between the angular sectors. Such defects can give rise to nipping of the hose which can harm sealing.
The invention seeks to remedy those drawbacks.
In accordance with the invention, the swaging die is placed in such a manner that at least the large end of the cavity lies around the portion to be swaged, and the first end of the flared length of said cavity lies beyond the hose in front of the free end thereof; and that while holding one of the two elements constituted by the ring and the swaging die axially, relative axial displacement is performed between said two elements in the rearwards direction (F), going from the free end referred to as the "front" end of the hose towards the other end thereof referred to as the "rear"
end.
Hy means of these dispositions, swaging is not restricted to the thickness of the ring. Further, by performing displacement rearwards, it is possible to considerably improve the mechanical strength of the assembly comprising the hose, the ring, and the tubular element because of the way the hose material (which ~ 2 ~ ~874f~

generally comprises rubber) behaves while the swaging operation is being performed.
Some of the hose material is pushed along during swaging, i.e. the material is subjected to creep, and it is pushed along in the displacement direction of the swaging die relative to the hose. If this displacement is towards the free end of the hose, then the material pushed along tends to accumulate towards said free end.
When no empty zone is provided inside the ring, the surface material is then subject to creep in the opposite direction such that overall the creep is rearward creep, i.e. it takes place in the direction opposite to the displacement of the swaging die relative to the ring.
It happens that the thickness of a flexible hose made of rubber type material varies quite considerably as a function of manufacturing parameters, so that the size of the tolerance range can be as much as about one millimeter. Because of local variations in thickness, the volume of excess material, i.e. the volume of material that creep tends to push away locally, is likewise highly variable. Consequently, the pressure of the hose-constituting material inside the ring is subject to local variations that are very large. To make the ring capable of withstanding such variations without deforming and to guarantee traction strength in the connection between the hose, the ring, and the tubular element, the thickness of the ring must be relatively great.
Further, when displacement takes place towards the free end of the hose, the hose-constituting material is subjected simultaneously to creep and to intense pressure variation, and that can affect its mechanical qualities.
During swaging by rearward displacement in accordance with the invention, the compression forces that act on the free end of the hose are continuously distributed over the entire circumference thereof, such that no zone of the hose is suddenly crushed or pinched.

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In addition, since swaging takes place progressively in the axial direction starting from the free end of the hose, the hose-constituting material is subjected to progressive creep that does not damage the hose and that serves, in particular, to maintain its required qualities concerning sealing of the assembly.
Swaging is thus performed both uniformly and progressively such that the ring and the hose are securely and reliably assembled together, with the hose presenting no nips or accumulations of matter at its end clamped between the ring and the rigid tubular element and no zones of weakness, in particular in the region of the end of the ring that is remote from the free end of the tube. Connection is ensured in reliable manner even when using rings of relatively small thickness.
Advantageously, the relative axial displacement of the ring and of the swaging die is stopped before the first end of the flared length reaches the end of the portion to be swaged that is remote from the free end of the hose.
In this way, the rear portion of the ring can be slightly flared and avoid running the risk of in uring the hose. To ensure that coupling devices are reliable and durable, they are subjected to endurance tests of ever increasing severity. One of these tests consists in causing the hose to oscillate relative to the ring. The fact that the rear portion of the ring is flared makes it possible to avoid the hose being damaged or even cut when such a test is performed.
The invention will be well understood and its advantages will appear better on reading the following detailed description of embodiments shown as non-limiting examples. The description refers to the accompanying drawings, in which:
Figure 1 is a longitudinal section showing a ring engaged on the free end of a flexible hose, itself engaged on a rigid tubular element, and also showing a 21~~14~
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swaging die with which a first implementation of the method of the invention is about to be performed;
Figures 2 and 3 show the method of the invention respectively at its beginning and at its end;

5 Figure 4 is a view analogous to Figure 1, in which a variant implementation of the invention is about to be applied; and Figure 5 shows the implementation of the method.
Figure 1 shows a flexible hose 10 whose free end l0a is engaged on a rigid tubular element 12, while a cylindrically-shaped ring 14 is engaged on the free end 10a.
To simplify the description below, it is assumed that the end l0a is the front end of the flexible hose 10. Since the figures are truncated, its remote or rear end is not shown.
In Figure 1, the ring 14 is shown prior to being swaged, and its diameter D is greater than the diameter of the hose 10.
Figure 1 also shows a swaging die 16 provided with an axial cavity 18. The cavity has a flared length 18a that flares from a first end 19a of diameter _d' and a second end 19b of diameter _d. The diameter _d is greater than the diameter D, which is itself greater than the diameter _d'. Adjacent to the first end 19a of the flared length, the cavity includes a cylindrical length 18b of diameter _d' which opens out into a narrow open end 17.
At its other end, the cavity has a large open end which, in the example shown, coincides with the second end 19b of the flared length which is frustoconical.
Figure 1 shows these various elements immediately before the beginning of the swaging process, in a position where the axis of the cavity is in alignment with the longitudinal axis A of the flexible hose, and the large open end 20 is facing rearwards.
Figure 1 also shows a tool 22 for holding the ring 14 axially, with the rear end I4b of the ring coming into - 2i787~~

abutment therewith. The tool is shown diagrammatically only in Figure 1. It may comprise two haws that are placed around the hose in such a manner as to co-operate with the free end 14b of the ring 14 so as to hold it in place during swaging.
To begin the swaging process, the swaging die is placed in such a manner that at least the large end 20 of the cavity is disposed around the ring to be swaged, while the first end 19a is placed in front thereof, beyond the front end of the hose. In other words, the die is displaced relative to the swaging ring in the direction of arrow F, i.e. going from the front end l0a of the hose towards its rear end, or at least until the end 20 of the cavity has come up to the front end 14a of the ring.
Swaging proper begins when the wall of the cavity starts to co-operate with the outer periphery of the ring.
To perform swaging, as shown in Figures 2 and 3, the swaging die 16 is displaced axially over the ring 14 in the direction of arrow F, i.e. rearwards.
It will be understood that while such displacement is taking place, since the ring is held in place by the holding tool 22, its outside diameter is progressively reduced down to the small diameter _d' of the cavity 18.
While this is taking place, progressive creep is being applied to the end l0a of the flexible hose.
At the end of swaging, the configuration shown in Figure 3 is reached in which the ring 14 is crimped on the end l0a of the hose which is securely clamped between the rigid tubular element 12 and the ring 14.
As can be seen in this figure, which shows the end of swaging, the axial displacement of the swaging die 16 relative to the ring 14 is preferably stopped before the smaller diameter end of the flared length 18a of the cavity has reached the rear end 14b of the ring 14 that is remote from the free end l0a of the hose 10. The rear end portion of the ring thus flares slightly and does not run the risk of in uring the hose.
In addition, it can be seen in the figures that the tubular element 12 has a radial swelling 13 in the vicinity of its own rear end. Swaging is preferably stopped before the ring has been totally swaged onto the swelling. This ensures a reliable connection between the elements of the coupling device while avoiding local crushing of the hose against the swelling, which could harm the mechanical qualities of the hose.
Once swaging has been completed, it suffices to disengage the ring from the swaging die by displacing the die in the direction opposite to arrow F, and to remove the holding tool 22.
- In Figures 1 to 3, the cylindrical ring 14 is swaged over substantially all of its length.
In some cases, as shown in Figures 4 and 5, it is desirable to swage only a portion of the ring. in these figures, elements analogous to those of Figures 1 to 3 are given the same reference numerals plus 100.
The ring 114 has a first portion 115a that is not to be swaged. In the example shown, this portion 115a extends forwards beyond the front end 110a of the flexible hose 110 and can serve as a housing for a sealing ring 117 or can be provided with a member for fixing to a rigid tubular endpiece to which it is desired to couple the hose 110.
It is thus only the rear portion 115b of the ring 114 that is to be swaged. The portion 115a constitutes an axial obstacle that makes it possible to use a one piece swaging die 16 under the conditions described above with reference to Figures 1 to 3. A swaging die 116 is therefore used which comprises two shells 116a and 116b.
To put this die into place around the ring, the shells 116a and 116b are firstly moved apart from each other so as to leave a passage that is large enough to allow the ring to pass through, or more precisely to ~ 217814 allow the front portion 115a thereof to pass through.
Axial swaging proper, during which the die is displaced in the direction of arrow F, begins after the two shells have been moved together around the ring so as to cause said passage to be eliminated.
Once the two shells have been assembled together in this way, a die cavity 118 is defined that has a flared length 118a and a smaller-diameter cylindrical length ll8b.
The small end 121 of the cavity situated remote from the large end 120 thereof is open. As can be seen in Figure 5, this makes it possible to place the die 116 about the portion 115b to be swaged while leaving the first portion 115a of the ring 114 projecting forwards beyond the die.
The portion 115b is swaged by displacing the die 116 in the direction of arrow F, i.e. by causing it to go from its start-of-swaging position shown in chain-dotted lines to its end-of-swaging position shown in solid lines. Throughout axial displacement of the swaging die, the ring is held axially by means of a swaging tool 122.
In the example shown in Figures 4 and 5, the tool 122 comprises jaws that co-operate with the front portion of the ring 114. More precisely, the jaws of the tool 122 are placed around the ring immediately behind the first portion 115 thereof, and come into abutment against a shoulder 114' so as to hold the ring and prevent it from being displaced rearwards during swaging.
In Figure 4, it can be seen that all of the second portion 115b situated behind the first portion 115a of the ring has a diameter, prior to swaging, that is greater than the diameter to which it is to be reduced by swaging. This applies in particular to the front end region 115c of the portion 115b which is situated directly behind the first portion 115a. As a result, when the shells are moved towards each other about the ring 114, prior to the die being displaced axially, a 217~~'40 preliminary step of radial swaging is performed in this region 115c, over a small fraction of the length of the portion that is to be swaged.
Preferably, as can be seen in Figures 4 and 5, the region 115c in which the preliminary step of radial swaging is performed extends forwards beyond the front end 110a of the flexible hose so that any drawbacks that may be associated with this operation of radial swaging have no effect on the hose.
It is also possible for the diameter of the intermediate portion 115c to be initially smaller than or equal to the swaging diameter, in which case there is no need for a preliminary radial swaging step.
Although the ring is held axially and the die is displaced in the direction of arrow F in the examples shown in the figures, it should be observed that it would be equally possible to perform swaging by holding the die axially and displacing the ring in the opposite direction to arrow F. The important point is that the two elements constituted by the ring and the die are displaced relative to each other with the die moving in the direction of arrow F, i.e. rearwards, along the portion to be swaged.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of swaging a ring engaged on a front free end of a flexible hose having the front free end and a rear end, said hose being engaged on a rigid tubular element, said ring having at least one portion to be swaged of a diameter greater than the diameter of the hose, the method implementing a swaging die provided with an axial cavity comprising a flared length that flares from a first end to a second end, the cavity having a large open end where the diameter of said cavity is substantially equal to the diameter of said flared length, at the second end thereof, wherein the swaging die is placed in such a manner that at least the large end of the cavity lies around the portion to be swaged, and the first end of the flared length of said cavity lies beyond the hose in front of the free end thereof; and wherein, while holding one of the two elements constituted by the ring and the swaging die axially, relative axial displacement is performed between said two elements in a rearwards direction, going from the front free end towards the rear end thereof.

2. A method according to claim 1, wherein the relative axial displacement of the ring and of the swaging die is stopped before the first end of the flared length reaches the end of the portion to be swaged that is remote from the front free end of the hose.

3 A method according to claim 1 or 2, wherein the ring is held axially and the swaging die is displaced axially over the portion to be swaged.

4. A method according to any one of claims 1 to 3, wherein a swaging die is used that comprises two shells, and wherein, to install the die around the ring, the shells are moved apart from each other to define a passage that is large enough to pass the ring, and said shells are moved towards each other around said ring until said passage is eliminated.

5. A method according to claim 4, wherein, while the shells are being moved towards each other around the ring, a preliminary radial swaging step is performed in the region of the end of the portion to be swaged that is adjacent to the front free end of the hose, over a length of said portion.