THREAD ROLLING TOOL

Abstract

The invention relates to a thread rolling tool for rolling and/or repairing a thread, comprising a clamping device to be fastened to a pipe end, and at least one profiled roll for rolling a thread into the pipe end or repairing a thread at the pipe end. According to the invention, the at least one profiled roll tapers in a direction in which the profiled roll advances such that a tapered, in particular a conical, thread can be rolled into the pipe end.

Description

The invention relates to a thread-rolling tool for rolling and/or repairing a thread, with (a) a clamping jig for fastening to a pipe end and (b) at least one profile roll for rolling a thread into the pipe end or for repairing a thread at the pipe end.

Such a thread-rolling tool is known, for example from DE 10 2012 004 701 A1. A disadvantage of such a thread-rolling tool is that it is suitable only for cylindrical threads. In other words, conical threads cannot be rolled with such a tool.

The task of the invention is to propose a thread-rolling tool that is suitable for rolling and/or repairing a tapering, especially a conical thread.

The invention accomplishes the task by a thread-rolling tool of the class in question, in which the at least one profile roll tapers in a feed direction of the profile roll, so that a tapering, especially a conical thread can be rolled into the pipe end.

The invention is based on the knowledge that a conical thread can be produced when a conical profile roll is used. If this profile roll on the pipe end that runs out taperingly, especially conically, the profile roll comes into contact with the pipe end over a large portion of its shell surface. By rotating the profile roll on a helical path around the longitudinal axis of the pipe end, the profile roll cuts a thread into the pipe end. The envelope contour of the profile roll, i.e. the contour of the profile roll without the grooves, is therefore preferably shaped in a manner complementary to the contour of the tapering thread to be produced.

It is particularly favorable when the profile roll has a conical basic structure, meaning that the groove crests lie on a conical surface. In this way a conical thread is obtained.

In the context of the present description, the clamping jig will be understood as a jig by means of which the thread-rolling tool can be fastened at the pipe end. In particular, the clamping jig is designed for insertion into the pipe at the pipe end and for fastening of the thread-rolling tool at the pipe end by enlarging the outside diameter of the clamping jig, for example by radial outward movement of clamping elements. The clamping jig may be actuated mechanically, pneumatically or hydraulically. In principle, the clamping jig may also be based on a different clamping principle; for example it may represent a freeze-clamping chuck. However, this is frequently associated with increased expense.

By the profile roll there will be understood a component by means of which a thread can be rolled into the pipe end. Preferably the profile roll has a conical envelope contour, which means that the profile roll can be produced by machining the profile into a conical portion in the portion provided with the profile used for rolling the thread.

By the feature that a thread can be rolled into the pipe end, it will also be understood in particular that an already existing but damaged thread can be so modified by means of the thread-rolling tool that a functionally effective thread is obtained.

Preferably the profile roll is pitchless. This has the advantage that the thread can be rolled and/or repaired with particularly high process reliability and in simple manner.

According to a preferred embodiment, the thread-rolling tool comprises a roll holder, on which the at least one profile roll is fastened and by means of which the at least one profile roll can be so guided helically around the pipe end that the at least one profile roll rolls a thread into the pipe end. By the feature that the profile roll can be guided helically around the pipe end, it will be understood that it can be guided on a helical path, which in particular is non-tapering, around the longitudinal axis of the pipe end. Certainly it is possible that the helical path tapers, which means that its diameter becomes smaller with increasing distance along the longitudinal axis, but this is not required. In addition, it is possible that the helical path widens. However, the thread-rolling tool is constructed particularly simply when the roll holder moves on a helical path that neither tapers nor flares around the longitudinal axis.

Preferably the roll holder is coupled by means of a thread with the clamping jig, so that a rotation of the roll holder around the pipe longitudinal axis of the pipe end leads to an axial movement of the roll holder along the pipe longitudinal axis. This represents a particularly simple and in addition process-reliable way of moving the roll holder on a helical path around the pipe longitudinal axis. It is particularly favorable when at least one of the threaded partners is made of hardened steel or of another hard material with a Rockwell hardness of at least 45 HRC. Thus the forces developed during rolling of the thread can be absorbed without this leading to excessive wear.

According to a preferred embodiment, the thread-rolling tool comprises at least one second profile roll, which is so fastened to the roll holder that the second profile roll, during rotation of the roll holder around the pipe longitudinal axis, rolls at least partly in grooves rolled by the first profile roll and that, in operation, it generates, in a direction at least partly opposed to a first passive force that acts on the first profile roll, a second passive force. The second profile roll therefore leads to a smaller torque that must be applied on the thread-rolling tool in order to roll the thread.

Alternatively to the second profile roll, it is possible that the thread-rolling tool has a counter-element, which generates a second passive force directed at least partly opposed to the first passive force. In this case, however, significant frictional force easily develops, which reduces the attainable quality for the thread and which greatly increases the torque necessary for actuation.

The second profile roll is preferably pitchless. It is favorable when the profile rolls are similarly structured, at least in the profiled portion. In particular, the profile rolls are preferably identical. With respect to an axis of rotation of the first profile roll, the profile of the second profile roll is offset relative to the profile of the first profile roll.

It is favorable but not required when at least one of the profile rolls is mounted to be axially displaceable. Preferably the first profile roll is mounted to rotate around a first profile roll axis of rotation and the second profile roll is mounted to rotate around a second profile roll axis of rotation, wherein the second profile roll axis of rotation forms an angle of 0° to 2° with the first profile roll axis of rotation.

According to a preferred embodiment, the first profile roll is mounted to rotate around a first profile roll axis of rotation and a first offset angle between the first profile roll axis of rotation (D14.1) and the pipe longitudinal axis amounts to at most 2°, especially at most 1°. Preferably, however, the angle is quantitatively as small as possible. The pipe longitudinal axis corresponds to the axis of rotation around which the roll holder can be rotated.

The fact that the offset angle exists does not necessarily mean that the longitudinal axis and the first profile roll axis of rotation intersect. The offset angle is calculated according to the mathematical rules for angle calculation from the direction vectors of the vectorial representation of axis of rotation and longitudinal axis, wherein the direction vectors are chosen in particular such that the offset angle amounts to at most 90°. The offset angle is always expressed positively, and so a theoretical angle of −0.5°, for example, between axis of rotation and longitudinal axis is regarded as an offset angle of 0.5°.

Preferably the second profile roll is mounted to rotate around a second profile roll axis of rotation and a second offset angle between the second profile roll axis of rotation and the pipe longitudinal axis amounts to at most 2°, especially at most 1°.

Preferably the thread-rolling tool comprises at least one third profile roll, which is so fastened to the roll holder that the third profile roll, during rotation of the roll holder around the pipe longitudinal axis, rolls at least partly in the grooves produced by the first profile roll or the second profile roll and that, in operation, it generates a third passive force, which together with the first passive force and the second passive force adds up vectorially to zero. In this way the thread can be generated with a particularly small torque.

It is particularly favorable when the third profile roll is mounted to rotate around a third profile roll axis of rotation and the third profile roll axis of rotation forms a third offset angle of at most 2°, especially of at most 1° with the pipe longitudinal axis, which corresponds to the axis of rotation of the roll holder.

According to a preferred embodiment, the clamping jig has an actuating connecting piece, by means of which the clamping jig can be clamped and loosened and which extends in the direction of the pipe longitudinal axis. In particular, the connecting piece is provided with a coupling structure, for example a male hexagon structure or a hexagon socket structure, so that the actuating connecting piece can be actuated with a complementary tool.

The invention additionally accomplishes the task by a method for producing or repairing a conical thread, with the steps of (i) fastening a thread-rolling tool according to the invention onto a pipe end by means of the clamping jig and (ii) rotating the roll holder, wherein the thread moves the roll holder axially along a pipe longitudinal axis of the pipe end, so that the at least one profile roll moves helically around the pipe longitudinal axis and rolls a conical thread into the pipe end or repairs the conical thread.

It is favorable when the pipe end runs out taperingly, especially conically. However, it is also conceivable that the pipe end does not run out taperingly. In this respect it is advantageous to omit the production of the conical portion. It is disadvantageous that much more material must be shaped, which greatly increases the process forces.

According to a preferred embodiment, a thread is rolled with a thread width that corresponds at most to a profile roll width of a profile shell surface of the profile roll.

There are shown in:

FIG. 1 a perspective view of a thread-rolling tool according to the invention,

FIG. 2 a section through the thread-rolling tool according to FIG. 1,

FIG. 3 a profile roll with a conical envelope body and

FIG. 4 a second perspective view of the thread-rolling tool.

FIG. 1 shows a thread-rolling tool 10, which has a clamping jig 12 as well as a first profile roll 14.1, a second profile roll 14.2 and a third profile roll 14.3. The profile rolls 14 (reference symbols without numerical suffix relate respectively to all corresponding objects) are mounted on a roll holder 16.

The profile roll 14.1 is mounted to rotate around a first profile roll axis of rotation D14.1, the second profile roll 14.2 can rotate around a second profile roll axis of rotation D14.2, the third profile roll 14.3 can rotate around a third profile roll axis of rotation D14.3. The three axes of rotation D14.1, D14.2 and D14.3 form an angle of at most 2°, especially at most 1° pairwise with one another.

The clamping jig 12 is designed for fastening to a pipe end 18 and for this purpose it has clamping elements 20.1, 20.2, . . . , which can be moved radially outward via a clamping cone 23. The clamping cone 22 has a thread—not visible in FIG. 1—and, by turning of an actuating connecting piece 24, can be thrust in axial direction corresponding to a pipe longitudinal axis L relative to the clamping elements 20.

The clamping jig 12 is joined to the roll holder 16 via a thread 26. If the clamping jig 12 is fastened securely to the pipe end 18, and if the roll holder 16 is rotated around the longitudinal axis L, the profile rolls 14 move on a helical path around the longitudinal axis L.

FIG. 2 shows the thread-rolling tool 10 in a section perpendicular to the pipe longitudinal axis L.

FIG. 3 shows a detail view of a profile roll 14. It can be seen that this tapers conically in the present embodiment. By this it will be understood that an imaginary envelope body 28 in the form of a truncated cone can be so fitted on the profile roll 14 that it contacts this along its shell surface. The points of contact lie on concentric rings, since the profile roll 14 is pitchless.

FIG. 4 shows the thread-rolling tool 10 in a further perspective view. It can be seen that the roll holder 16 has a coupling structure 30, which in the present case is formed by a male hexagon structure. The coupling structure 30 is designed for interlocking interaction with a wrench having complementary coupling structure.

A method according to the invention is carried out by the fact that firstly the thread-rolling tool 10 is fastened to the pipe end 18. For this purpose the thread-rolling tool 10 is inserted with its clamping jig 12 into the pipe end 18. Then the fastening connecting piece 24 is turned with a suitable tool, so that the jig 12 fastens the threading-roll tool 10 on the pipe end 18. Then the roll holder 16 is rotated. This may be done, for example, by attaching an associated wrench to the coupling structure 30 and turning it. Obviously it is also possible to use a drive, for example an electric, pneumatic or hydraulic drive, for rotation of the roll holder 16.

In addition, a positioning machine, especially a machine tool or a robot, which comprises a thread-rolling tool according to the invention, is according to the invention. The positioning machine may be designed for automatic insertion of the thread-rolling tool 10 into a pipe end 18, for clamping of the clamping jig and for rolling of the roll holder 16. If necessary, the positioning machine has a tool changer and/or a workpiece changer, so that a plurality of pipes can be machined at their respective pipe ends by cutting a tapering thread, especially a conical thread.

FIG. 1 shows a profile roll width B14 of the profile roll. When the profile roll 14.1 is in contact over its full profile roll width B14 with the thread that has just been rolled, the thread has a thread width that corresponds to B14.

LIST OF REFERENCE SYMBOLS

• 10 Thread-rolling tool
• 12 Clamping jig
• 14 Profile roll
• 16 Roll holder
• 18 Pipe end
• 20 Clamping element
• 22 Clamping cone
• 24 Actuating connecting piece
• 26 Thread
• 28 Envelope body
• 30 Coupling structure
• D_14.1 First profile axis of rotation
• D_14.2 Second profile axis of rotation
• D_14.3 Third profile axis of rotation
• L Pipe longitudinal axis

Claims

1. Thread-rolling tool for rolling and/or repairing a thread, with

a) a clamping jig (12) for fastening to a pipe end (18) and

b) at least one profile roll (14.1) for rolling a thread into the pipe end (18) or for repairing a thread at the pipe end (18),

wherein

c) the at least one profile roll (14.1) tapers in a feed direction of the profile roll (14), so that a tapering, especially a conical thread can be rolled into the pipe end (18).

2. Thread-rolling tool according to claim 1, wherein the profile roll (14) is pitchless.

3. Thread-rolling tool according to claim 1, comprising

a roll holder (16), on which the at least one profile roll (14.1) is fastened and by means of which the at least one profile roll (14.1) can be so guided helically around the pipe end (18) that the at least one profile roll (14.1) rolls a thread into the pipe end (18).

4. Thread-rolling tool according to claim 1, wherein

the roll holder (16) is coupled by means of a thread (26) with the clamping jig (12), so that a rotation of the roll holder (16) around a pipe longitudinal axis (L) of the pipe end (18) leads to an axial movement of the roll holder (16) along the pipe longitudinal axis (L).

5. Thread-rolling tool according to claim 1, comprising at least one second profile roll (14.2), which is so fastened to the roll holder (16) that

the second profile roll (14.2), during rotation of the roll holder (16) around the pipe longitudinal axis (L), rolls at least partly in grooves rolled by the first profile roll (14.1) and wherein,

in operation, it generates, in a direction at least partly opposed to a first passive force that acts on the first profile roll (14.1), a second passive force.

6. Thread-rolling tool according to claim 5, wherein

the first profile roll (14.1) is mounted to rotate around a first profile roll axis of rotation (D14.1) and a first offset angle between the first profile roll axis of rotation (D14.1) and the pipe longitudinal axis amounts to at most 2°, especially at most 1° and/or

the second profile roll (14.2) is mounted to rotate around a second profile roll axis of rotation (D14.1) and a second offset angle between the second profile roll axis of rotation (D14.2) and the pipe longitudinal axis amounts to at most 2°, especially at most 1°.

7. Thread-rolling tool according to claim 5, comprising at least one third profile roll (14.3), which is so fastened to the roll holder (16) wherein

the third profile roll (14.3), during rotation of the roll holder (16) around the pipe longitudinal axis (L), rolls at least partly in the grooves rolled by the first profile roll (14.1) and/or the second profile roll (14.2) and wherein,

in operation, it generates a third passive force, which together with the first passive force and the second passive force preferably adds up vectorially to zero.

8. Thread-rolling tool according to claim 7, wherein

the third profile roll (14.3) is mounted to rotate around a third profile roll axis of rotation and

the third profile roll (14.3) is mounted to rotate around a third profile roll axis of rotation (D14.3) and a third offset angle between the third profile roll axis of rotation (D14.3) and the pipe longitudinal axis amounts to at most 2°, especially at most 1°.

9. Method for producing or repairing a conical thread, with the steps of:

(i) fastening a thread-rolling tool (10) according to claim 1 onto a pipe end (18) by means of the clamping jig (12) and

(ii) rotating the roll holder (16), wherein the thread moves the roll holder (16) axially along a pipe longitudinal axis (L) of the pipe end (18), so that the at least one profile roll (14) moves helically around the pipe longitudinal axis (L) and rolls a conical thread into the pipe end (18).

10. Method according to claim 9, wherein a thread is rolled with a thread width that corresponds at most to a profile roll width (B14) of a profiled shell surface of the profile roll (14).