CUTTING RING FITTING

Abstract

A cutting ring fitting for a thin-walled pipe, includes: a connecting body having a tapered cone; a cutting ring; a union nut which can be screwed onto the connecting body; and a reinforcing sleeve for insertion into the pipe, the reinforcing sleeve having an axial slot. A pipe includes such a cutting ring fitting, and a method mounts such a cutting ring fitting on a thin-walled pipe.

Claims

1. A cutting ring screw fitting for a thin-walled pipe, having a connecting body that has a clamping cone, having a cutting ring, having a union nut that can be screwed onto the connecting body, as well as having a reinforcement sleeve for introduction into the pipe, wherein the reinforcement sleeve (4) has an axial slot (43).

2. The cutting ring screw fitting according to claim 1, wherein the outside diameter of the reinforcement sleeve (4) is greater than the inside diameter of the pipe (5), wherein a reduction of the outside diameter of the reinforcement sleeve (4) to a diameter that is less than the inside diameter of the pipe (5) is made possible by compressing the edges of the axial slot (43).

3. The cutting ring screw fitting according to claim 2, wherein the outside diameter of the reinforcement sleeve amounts to at least 1.02 times, preferably at least 1.03 times, particularly preferably at least 1.04 times the nominal inside diameter of the pipe.

4. The cutting ring screw fitting according to claim 1, wherein the width b.sub.slot of the axial slot is calculated to be b.sub.slot=D.sub.sleeve.Math.3%.Math.τ (D.sub.sleeve=outside diameter of the reinforcement sleeve).

5. The cutting ring screw fitting according to claim 1, wherein the reinforcement sleeve (4) is provided, at its end, with a collar (41) that runs around the circumference, at least in certain regions, so as to lie against the pipe (5).

6. The cutting ring screw fitting according to claim 1, wherein the axial slot (43) runs over the entire length of the reinforcement sleeve (4).

7. The cutting ring screw fitting according to claim 1, wherein the reinforcement sleeve (4) has a cone-shaped end section (42) at one end.

8. A pipe having the cutting ring screw fitting according to claim 1, wherein the reinforcement sleeve (4) lies against an inner wall of the pipe (5) under a preload and has an axial slot (43), wherein the cutting ring (3) lies against the clamping cone (13) of the connecting body (1) and is pressed onto the pipe (5) by way of the screw connection of connecting body (1) and union nut (2), in such a manner that the blades (31) of the ring (3) cut into the outer wall of the pipe (5).

9. The pipe according to claim 8, wherein the pipe (5) has an inside diameter that lies in the range of the tolerance of its nominal inside diameter, wherein the width b.sub.slot of the axial slot (43) of the reinforcement sleeve (4) is calculated to be b.sub.slot=D.sub.sleeve.Math.3%.Math.τ(D.sub.sleeve=outside diameter of the reinforcement sleeve).

10. A method for mounting the cutting ring screw fitting according to claim 1 on a thin-walled pipe (5), wherein first, an axially slotted reinforcement sleeve (4), the outside diameter of which sleeve is greater than the pipe inside diameter, and which sleeve has a collar (41), on the end face, that runs circumferentially at least in certain sections, is compressed, and subsequently, the reinforcement sleeve (4) that has been preloaded in this way, so as to reduce its outside diameter, is inserted into the pipe (5) until the end face of the pipe (5) lies against the collar (41) of the reinforcement sleeve (4), wherein the reinforcement sleeve (4) is relaxed until its outer mantle surface lies against the inner wall of the pipe (5), and afterward, connecting piece (1), cutting ring (3), and union nut (2) are pushed onto the pipe (5) and then connecting piece (1) and union nut (2) are screwed together with one another.

11. The method according to claim 10, wherein the width b.sub.slot of the axial slot of the reinforcement sleeve (4) is calculated to be b.sub.slot=D.sub.sleeve.Math.3%.Math.τ(D.sub.sleeve=outside diameter of the reinforcement sleeve).

12. The method according to claim 10, wherein the axially slotted reinforcement sleeve (4) is compressed until the edges of the axial slot (43) lie against one another.

13. A reinforcement sleeve for use in the cutting ring screw fitting according to claim 1, having a sleeve body that is provided with a circumferential collar (41) at its end, at least in certain regions, and that is separated by an axial slot (43) over its entire length, wherein the sleeve body is elastic, in such a manner that the edges of the axial slot (43) can be reversibly pressed against one another.

14. The reinforcement sleeve according to claim 13, wherein the width b.sub.slot of the axial slot (43) is calculated to be b.sub.slot=D.sub.sleeve.Math.3%.Math.τ(D.sub.sleeve=outside diameter of the reinforcement sleeve).

15. The reinforcement sleeve according to claim 13, wherein this sleeve is produced from brass or spring steel.

Description

[0014] Other further developments and embodiments of the invention are indicated in the other dependent claims. An exemplary embodiment of the invention is shown in the drawings and will be described in detail below. The figures show:

[0015] FIG. 1 the schematic representation of a thin-walled pipe provided with a cutting ring screw fitting [0016] a) in partial section; [0017] b) in longitudinal section;

[0018] FIG. 2 the representation of the pipe with cutting nut and reinforcement sleeve from FIG. 1 in an exploded representation;

[0019] FIG. 3 the representation of the arrangement from FIG. 2 in partial section;

[0020] FIG. 4 the representation of the pipe section with cutting ring and reinforcement sleeve of the cutting ring screw fitting from FIG. 1 (mounted) [0021] a) in a side view; [0022] b) in partial section; [0023] c) in longitudinal section;

[0024] FIG. 5 the detail representation of the screw fitting sleeve of the cutting ring screw fitting according to FIG. 1 [0025] a) in a first spatial view; [0026] b) in a second spatial view; [0027] c) in a third spatial view.

[0028] FIG. 6 the schematic representation of the connecting body of the cutting ring screw fitting from FIG. 1, and

[0029] FIG. 7 the schematic representation of the union nut of the cutting ring screw fitting from FIG. 1.

[0030] The cutting ring screw fitting for a thin-walled pipe 5, chosen as an exemplary embodiment, comprises a connecting body 1, a union nut 2 that can be screwed onto the latter, and a cutting ring 3 arranged between connecting body 1 and union nut 2, as well as a reinforcement sleeve 4 for reinforcing the pipe 5 in the connection region. In the exemplary embodiment, the pipe 5 is a welded stainless steel pipe having a nominal inside diameter of 32 mm and a wall thickness of 1.5 mm.

[0031] In known manner, the connecting body 1 has a first cylindrical bore 11, the inside diameter of which corresponds to the outside diameter of the pipe 5 to be accommodated. A second bore 12 having a smaller diameter, which essentially corresponds to the inside diameter of the pipe 5, follows the first bore 11. In the transition between the first bore 11 and the second bore 12, a step is formed for contact with the end face surface of the pipe 5. On its end opposite to the second bore 12, the first bore 11 makes a transition into a conical bore, which forms a clamping cone 13. Lying opposite to the first bore 11, the connecting body 1 furthermore has an outside thread 14 on the outside, onto which the union nut 2 can be screwed.

[0032] The union nut 2 has a radially inwardly directed collar 22 that follows its inside thread 21, the inside diameter of which collar essentially corresponds to the outside diameter of the pipe 5. In this regard, the collar 22 has a conical section 23 in the transition region to the inside thread 21.

[0033] The cutting ring 3 has two blades 31 that run radially circumferentially, each of which is radially directed in the direction of the outer surface of an accommodated pipe 5. At one end, the cutting ring 3 has a first cone 32 on the outside, to lie against the cone-shaped section 23 of the union nut 2. On its side opposite the first cone 32, the cutting ring 3 has a second cone 33 to lie against the clamping cone 13 of the connection body 1, which cone narrows outward in the direction opposite the first cone 32.

[0034] The reinforcement sleeve 4 is configured cylindrically and has an outside diameter of 33.9 mm. At one end, a collar that projects radially outward is formed circumferentially onto the reinforcement sleeve 4, the width of which collar essentially corresponds to the wall thickness of the pipe 5 of 1.5 mm. On its side that lies opposite the collar 41, the reinforcement sleeve 4 has a cone-shaped end section 42. Over its entire length, the reinforcement sleeve 4 is furthermore provided with an axial slot 43. In the exemplary embodiment, the axial slot 43 has a width of 3 mm.

[0035] For mounting the cutting ring screw fitting, first the axially slotted reinforcement sleeve 4 is compressed until the edges of the axial slot 43 lie against one another, and it is inserted into the pipe 5 in this preloaded state, until the pipe lies against the collar 41 of the reinforcement sleeve 4, which relaxes within the pipe 5 so that is lies against the inner wall of the pipe 5 circumferentially, due to the preload force. Existing inside diameter tolerances of the pipe are thereby equalized. Subsequently, the union nut, the cutting ring, and the connecting body are set onto the pipe 5, until the collar 41 of the reinforcement sleeve 4, arranged on the end side in the pipe 5, lies against the step formed between the first bore 11 and the second bore 12 of the connecting body 1. Subsequently, the union nut 2 is screwed onto the outside thread 14 of the connecting body 1 with its inside thread 31, and thereby the cutting ring 3, arranged between connecting body 1 and union nut 2, is pressed into the clamping cone 13 of the connecting body 1. As a result, the cutting ring 3 is narrowed in its front part, and thereby it cuts into the outer mantle of the pipe 5 with its blades 31. Due to the reinforcement sleeve 4 arranged in the connecting region of the pipe 5, the forces that thereby act radially on the pipe 5 are additionally absorbed, and thereby deformation of the thin-walled pipe 5 is effectively counteracted. In this regard, the reinforcement sleeve is given stability, for one thing, in that the sides of the slot 43 press against one another; alternatively—in the presence of greater tolerances—the required counter-holding force is generated by the friction forces between the outer mantle surface of the reinforcement sleeve 4 and the inner mantle surface of the pipe 5.