Crimp connection arrangement for pressurized pipes

A crimp connection arrangement for pressurized pipes with a compression sleeve and a pipe, wherein an end piece of the pipe is insertable into the compression sleeve and wherein by an application of an external force to a pressing portion of the compression sleeve, a connection is achievable between the compression sleeve and the end piece of the pipe.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage application under 35 U.S.C. § 371 of International Application No. PCT/EP2012/073956, filed on Nov. 29, 2012, and claims benefit to European Patent Application No. 11 191 218.4, filed on Nov. 29, 2011. The International Application was published in English on Jun. 6, 2013, as WO 2013/079590 A2 under PCT Article 21(2).

FIELD

The invention relates to a crimp connection arrangement for pressurized pipes with a compression sleeve and a pipe.

BACKGROUND

In known compression connections, as they are, for example, described in U.S. Pat. No. 4,328,982, the compression sleeve has an inner serration, which enters due to the force applied for producing the connection, the outer wall of the pipe. Thus, different and even conflicting material requirements for the respective portions of the compression sleeve result. The tubular outer portion of the compression sleeve, which is acted upon by the force, has to be deformed and requires a ductile material. After the pressing, the pipe as well as the compression sleeve relax according to the elastic deformation portion. To produce a radial pre-biasing between the compression sleeve and the pipe, the elastic relaxation of the compression sleeve has to be smaller than the elastic relaxation of the pipe. This can be achieved by a compression sleeve material of lower strength compared to the pipe material. However, for the serration of the compression sleeve, rather a material of high strength and hardness is required, to ensure the penetration into the pipe material. A disadvantage of the state of the art results from this inconsistency.

SUMMARY

An aspect of the invention provides a crimp connection arrangement for a pressurized pipes, the arrangement comprising: a compression sleeve including a pressing portion; a sleeve-like retaining element including an inner serration on at least a portion of an inner surface of the retaining element and an outer serration on at least a portion of an outer surface of the retaining element; and a pipe including an end piece, the end piece of the pipe being insertable into the compression sleeve, wherein, by applying a force onto the pressing portion of the compression sleeve, a connection is achievable between the compression sleeve and the end piece of the pipe, wherein the separate, sleeve-like retaining element is provided between the compression sleeve and the end piece of the pipe, wherein the retaining element includes a material of greater hardness than the compression sleeve and the pipe, wherein the retaining element is reducible in its diameter at least partially by the force applied onto the pressing portion, and wherein teeth of the inner serration are arranged in axial direction of the retaining element in a clearance between two adjacent teeth of the outer serration.

An aspect of the invention relates to a crimp connection arrangement for pressurized pipes with a compression sleeve and a pipe, wherein an end piece of the pipe is insertable into the compression sleeve and wherein by an application of a force to a pressing portion of the compression sleeve, a connection is achievable between the compression sleeve and the end piece of the pipe.

The crimp connection arrangement according to an aspect of the invention for pressurized pipes is provided to produce a compression connection between a compression sleeve and a pipe, wherein an end piece of the pipe is insertable into the compression sleeve and a connection can be produced between the compression sleeve and the end piece of the pipe by the application of a force onto a pressing portion of the compression sleeve. In this case, the connection is especially partially form-fitting and partially force-fitting. The external force application is achieved generally directed radially inwards and is also designated as compressing.

According to the invention, a separate, sleeve-like retaining element is provided between the compression sleeve and the end piece of the pipe, wherein the retaining element is made from a material with greater hardness than the compression sleeve and than the pipe. The retaining element is provided for entering by the force application the inner surface of the compression sleeve and the outer surface of the pipe, to produce the form- and/or force-fitting connection. The separation of the separate retaining element from the compression sleeve according to the invention solves the above described contradicting material requirements. For example, an inner diameter of the compression sleeve can, advantageously, be generally constant across the pressing portion; thus, the compression sleeve has a smooth-walled bore. The retaining element is described according to the invention as sleeve-like, as the retaining element has a diameter, which is larger than the outer diameter of the pipe and smaller than the inner diameter of the compression sleeve, so that the retaining element can be arranged like a sleeve between the pipe and the compression sleeve. The retaining element according to the invention can, however, differ from a sleeve in respect of structure and shape, to ensure, that the retaining element is reducible in its diameter at least portion-wise by means of a force application onto the pressing portion. Thus, it can, advantageously, be achieved, that the retaining element is deformable in its sleeve-like structure, but because of its higher strength, compared to the pipe and the compression sleeve, enters the same.

Preferably, the retaining element has a shape, which has, compared to a sleeve, a lower stability against the force application onto the pressing portion. A preferred embodiment of the crimp connection arrangement provides that the retaining element is formed as a slotted sleeve. This means, that at least one slot reduces the stability of the sleeve. The at least one slot is essentially arranged in axial direction of the sleeve, but can also extend partially or portion-wise in circumferential direction. A single slot can be formed all through in axial direction. With a multitude of slots, this would lead to the fact, that the retaining element is separated into two or more sleeve elements.

Preferably, a multitude of slots is provided in axial direction of the sleeve, wherein the slots extend over a portion of the axial length of the sleeve. Thus, the sleeve remains to be a single piece and is easier to handle. The slots can all extend from one sleeve end or from the one and the other sleeve end, preferably alternatingly. Preferably, the slots extend from the pipe-sided end of the retaining element, while the end of the retaining element, facing the compression sleeve, has no slots. Thus, a sealing element can abut the non-slotted end.

The retaining element has a serration, which advantageously facilitates the penetration into the surface of the compression sleeve and of the pipe, on its inner side and/or its outer side. Furthermore, the serration has, preferably, shallow and steep tooth flanks, wherein the steep tooth flanks provide a barb-like protection against a pulling-out of the pipe from the compression sleeve. The retaining element preferably comprises an inner serration on at least a portion of its inner surface and an outer serration on its outer surface, wherein a spacing of adjacent teeth of the inner serration and of the outer serration in axial direction of the retaining element is equal and wherein the teeth of the inner serration are arranged in axial direction of the retaining element in a clearance between two adjacent teeth of the outer serration. In other words, the teeth of the inner serration and of the outer serration are arranged alternately along the axial direction of the retaining element, in particular, a tooth of the outer serration is arranged in the middle between two adjacent teeth of the inner serration, respectively. The retaining element is thus advantageously stressed in an axial direction when the force is applied to the pressing portion of the compression sleeve.

Furthermore preferably, the serrations comprise teeth with one higher-angeled, steep tooth flank and one lower-angeled shallow tooth flank, wherein the teeth of the outer serration have the steep tooth flank facing the end of the retaining element where the pipe is inserted and/or wherein the teeth of the inner serration have the shallow tooth flank facing the end of the retaining element where the pipe is inserted, thus achieving the advantageous barb-like protection against a pulling-out of the pipe from the compression sleeve referred to above.

Preferably, an inner diameter of the compression sleeve is essentially constant across the pressing portion. Thus, the compression sleeve is essentially less complex to manufacture than with an internal serration. The compression sleeve can, preferably, be manufactured with a smooth bore and without different hardness portions with less effort.

Preferably, the retaining element has at its pipe-sided end, which is the end where the pipe is inserted into the retaining element, a portion with constant inner diameter, i.e. without serration at the inner side. Thus, a notching by the penetration of the serration in the area of the pipe-sided end of the compression sleeve, weakening the structure of the pipe, is prevented.

Preferably, the retaining element can be pre-assembled in the compression sleeve. Furthermore, the possibility exists, that a sealing element is connected to the retaining element, for example bonded or vulcanised. For producing the compression connection, only the pipe end has to be inserted into the compression sleeve with the pre-assembled retaining element and the sealing element and the pressing procedure has to be carried out. An abutment within the compression sleeve can also be omitted. The outer diameter of the retaining element is, preferably, slightly larger than the inner diameter of the compression sleeve, a so-called interference fit. Thus, the retaining element can be pre-assembled with the compression sleeve to form one component, for example by means of axial pressing of the retaining element into the compression sleeve. When the retaining element is pre-assembled with the compression sleeve, the sealing element can advantageously be clamped axially between the compression sleeve and the retaining element. In this preferred embodiment it is not necessary, that the sealing element is connected to the retaining element.

FIGS. 1 to 3show an embodiment of the crimp connection arrangement according to the invention in a non-compressed condition, in three slightly different representations. Therefore,FIGS. 1 to 3are described together.

The crimp connection arrangement according to the invention has a compression sleeve1and a pipe2, wherein an end piece of the pipe2is inserted into the compression sleeve1and a connection between the compression sleeve1and the end piece of the pipe2can be produced by a radially directed applied force onto the pressing portion6of the compression sleeve1. A sleeve-like retaining element3between the compression sleeve1and the end piece of the pipe2is separate from the compression sleeve1and is made from a material of greater hardness than the compression sleeve1and the pipe2. The retaining element3is reducible despite its hardness in its diameter at least portion-wise by the applied force onto the pressing portion, i.e., such that the retaining element3is pressed into the surface of the pipe2. The retaining element3penetrates, in this case, the inner surface of the compression sleeve1. The deformability of the retaining element3results from its shape. The basic sleeve-like structure of the retaining element3is weakened by a multitude of slots5(FIGS. 2 and 3), compared to a non-slotted sleeve, such that a generally elastic deformation is achieved by the applied force onto the pressing portion6. The plastic deformation of the compression sleeve1prevents later a relaxation of the retaining element3.

Preferably, the retaining element3has an outer serration7and an inner serration11. The serrations7,11penetrate advantageously easier the surfaces of the pipe2and of the compression sleeve1. In a pipe-sided end piece of the retaining element3, the retaining element3has no inner serration11, to prevent a notching effect in the pipe2.

The slots5extend in an axial direction across a partial length of the retaining element3. On the side, facing the compression sleeve, the retaining element3is not slotted all through, so that a continuous abutment face for a seal4is formed, which seal4can be bonded or vulcanised to the retaining element3.

The compression sleeve1has, neighbouring the pressing portion6, an abutment10for the crimping dies, by means of which the applied external force acts onto the compression sleeve1.

InFIG. 4,FIG. 1is shown in a larger scaled sectional view. The teeth of the outer serration7and of the inner serration11are visibly arranged alternatingly along an axial direction of the retaining element3. The sealing element4is arranged in a slot between the retaining element3and an abutment inside the compression sleeve1.

InFIGS. 5 through 8, a simplified embodiment of the compression sleeve1is shown in sectional views, having the form of a blind plug. That is, however, not relevant with regard to the invention. The pipe2is inserted into the compression sleeve1and abuts an abutment inside the compression sleeve1. The retaining element3is arranged in between the compression sleeve1and the pipe2. A sealing is not depicted.

InFIG. 6,FIG. 5is shown on a larger scale. Perceptibly, the teeth of the inner serration11are respectively arranged in the middle between two adjacent teeth of the outer serration7. With respect toFIG. 6, a further preferred embodiment is described, wherein the serrations7,11each comprise teeth with one steep flank9and one shallow flank8, depicted by a dotted line. The steep flanks9of the outer serration7and the shallow flanks8of the inner serration11are each facing towards the end of the compression sleeve1, where the pipe is inserted, whereas the steep flanks9of the inner serration11and the shallow flanks8of the outer serration7are facing towards the opposite direction. Thus, a serration7,11is provided, whereby a barb-like resistance against pulling out of the pipe2from the compression sleeve1is advantageously achieved.

FIG. 7shows the crimp connection arrangement according toFIG. 5, but in a compressed or crimped condition, i.e. after the force has been applied onto the pressing portion6. In the pressing portion6, the compression sleeve1is plastically deformed. The retaining element3is crimped between the compression sleeve1and the pipe in such a way, that the serrations7,11have penetrated the inner surface of the compression sleeve1and the outer surface of the pipe2.

InFIG. 8, a detail marked with reference numeral D inFIG. 7is shown on a larger scale. Therein, the penetration of the pipe2and the compression sleeve1by the serrations7,11is perceptible. The retaining element3, due to the alternating arrangement of the respective teeth of the inner serration11and the outer serration7, is radially stressed. Thus, an advantageously fast connection of the pipe2in the compression element1is provided, with the retaining element3as a connecting link.

FIG. 9shows an embodiment of the retaining element3in the form of a slotted sleeve with slots5running in parallel in a longitudinal or axial direction along a part of the length of the sleeve, starting alternately on one and the other end of the retaining element3. At the end of the retaining element3where the pipe is inserted, a part of the inner surface of the retaining element3does not comprise the inner serration11.

REFERENCE NUMERALS LIST