DE102023115583A1 - Device and method for whirling an internal thread - Google Patents

Abstract

A device for whirling an internal thread (3) comprises a whirling mandrel (4) on which a cutting tool (5) provided for producing the internal thread (3) is located, and an elongated guide part (7) supporting the whirling mandrel (4), at the end of which a guide section (8) is formed, which is provided as a section with a diameter that is enlarged in relation to the adjacent region of the guide part (7) for contacting an inner peripheral surface (10) of a workpiece, wherein the whirling mandrel (4) is arranged eccentrically to the guide section (8). The whirling mandrel (4) is arranged opposite the guide part (7), wherein means (11, 12) for aligning the whirling mandrel (4) in relation to the guide part (7) are formed on the end faces of the whirling mandrel (4) and of the guide section (8).

Description

The invention relates to a device for whirling an internal thread designed according to the preamble of claim 1. The invention further relates to a method for the machining production of an internal thread by whirling.

A method for producing an internal thread by whirling is known, for example, from EP 1 820 592 A2 known. The EP 1 820 592 A2 deals with the production of multi-start thread-like profiles, whereby it is proposed to synchronize the speeds and angles of rotation of a workpiece and a cutting tool in such a way that the production of at least some of the threads of the profile takes place continuously. A whirling mandrel used for cutting, which is used in the EP 1 820 592 A2 The machine described is guided in a so-called support head, which is a tubular part. The support head has a cylindrical guide section at its end as a section of enlarged diameter, which is guided in a sliding manner on an inner surface of the workpiece. The whirling mandrel projects beyond the support head including the guide section and carries a cutting tool in the area that projects beyond the guide section. In the case of the machine according to the EP 1 820 592 A2 The cutting tool comprises a tool body equipped with a carbide cutting insert.

In general, thread whirling is a circular thread milling process. A whirling tool rotates at high speed while the workpiece rotates comparatively slowly. The tool and workpiece can rotate either in parallel or in opposite directions. In any case, relative movements between the tool and the workpiece in the axial direction must be coordinated with the profile to be created and with the rotational movement of the workpiece. Since both the tool and the workpiece are rotationally driven, machine tools with two opposing spindles are particularly suitable for thread whirling.

The DE 199 22 891 C2 discloses a tool holder with a rotatably driven tool spindle for whirling internal threads, wherein the axis of rotation of the tool runs at an angle to the axis of the threaded hole in the workpiece. In this case, a drive spindle is connected to a tool spindle by a double-link universal joint shaft. This is intended to provide adjustment options that allow the tool holder to be used to produce different thread pitches.

The DE 1 280 638 A The subject is a device for whirling steep and/or long internal threads. According to the DE 1 280 638 A A lifting movement of a vortex mandrel is derived from an inclined disc on which the vortex mandrel is supported in an articulated manner via a sliding shoe.

One in the DE 10 2011 110 131 B4 The whirling device described comprises a tool which is arranged on a spindle which can be driven in a rotating and linearly displaceable manner. It is possible to achieve either only a rotary movement or only a linear movement of the spindle or to achieve a simultaneous rotary and linear movement.

The invention is based on the object of achieving progress over the aforementioned prior art in the whirling of internal threads, whereby a particularly favorable relationship between manufacturing effort and precision is also sought for threads with a large length/diameter ratio.

This object is achieved according to the invention by a device designed for whirling an internal thread with the features of claim 1. The object is also achieved by a method for whirling an internal thread according to claim 8. The embodiments and advantages of the invention explained below in connection with the manufacturing method, i.e. machining method in the form of whirling, also apply mutatis mutandis to the machining device provided for whirling internal threads.

The cutting device according to the application comprises, in a basic concept known per se, a whirling mandrel on which a cutting tool intended for producing the internal thread is located. The cutting device also comprises an elongated guide part that supports the whirling mandrel. A guide section is formed at the end of the guide part, which has an enlarged diameter in relation to the adjacent area, i.e. shaft, of the guide part and is intended for contacting an inner circumferential surface of a workpiece.

The shaft of the guide part, like the guide section provided by the guide part, does not necessarily have a circular cross-section. By designing the cross-section of the guide section in which contact is only made between the inner surface of the workpiece and the surface of the guide section at defined surface sections that are small compared to the total surface of the guide section, the risk of Clamping of the tool in the workpiece bore can be effectively counteracted. In particular, the outer contour of the guide part can be left free where no supporting force is required. For example, contact with the workpiece bore is only made on two separate surfaces, which are arranged opposite the force introduction by the machining process. During machining, i.e. the machining of the internal thread by whirling, the whirling mandrel is always arranged eccentrically to the guide section.

In the device according to the application, the vortex mandrel is arranged opposite the guide part, wherein means for aligning the vortex mandrel in relation to the guide part are formed on the opposite end faces of the vortex mandrel and the guide section.

If the workpiece, which already has a hollow shape with a continuous cylindrical inner circumferential surface, i.e. a through hole, before whirling, is in the machining device, the accessibility of the hole from both sides can be used to mechanically support the whirling mandrel with high efficiency during machining and to machine the workpiece both at high machining speed and with precision. The machining device can be used for producing single-start threads as well as for producing multi-start threads or other structured inner surfaces, and is particularly suitable for small diameters and large hole depths compared to the hole diameter.

There are various design options when it comes to the type of cutting tool. For example, the cutting tool can be a cutting head that is an integral part of the whirling mandrel. Instead of a cutting head that is formed in one piece with the whirling mandrel, there can also be a cutting head that is interchangeably attached to a shaft of the whirling mandrel. Designs can also be implemented in which the cutting tool is in the form of at least one interchangeable cutting plate attached to the whirling mandrel. In all cases, the cutting tool can have either a single cutting edge or a plurality of cutting edges, for example three cutting edges.

The means mentioned for aligning the whirling mandrel in relation to the guide part allow a relative rotation between the whirling mandrel and the guide part and are formed, for example, by a pin and an associated bore, whereby the pin is located on one of the two parts, whirling mandrel and guide part, and the bore is located on the front side of the other part. A purely segment-like formation of contours for aligning the whirling mandrel with respect to the guide part during machining is also possible.

If there is a pin-bore combination, the pin is located on the whirling mandrel in a section that protrudes beyond the cutting tool, while the guide section is provided with a corresponding bore. Conversely, the guide section can also be provided with a pin-shaped extension that engages in a front-side bore in the whirling mandrel.

With the same functionality, an interaction between the swivel mandrel and the guide part can also be provided via a separate bearing.

• - Breitstellung eines rohrförmigen, das heißt eine Durchgangsbohrung aufweisenden, mit dem Innengewinde zu versehenden Werkstücks,
• - Aufspannung des Werkstücks mittels einer Mittenantriebsspindel einer Werkzeugmaschine, so dass die Durchgangsbohrung von beiden Seiten her zugänglich ist,
• - Bereitstellung eines Wirbeldorns und eines langgestreckten Führungsteils, wobei an den Stirnseiten des Wirbeldorns sowie des Führungsteils Ausrichtkonturen ausgebildet sind, die eine definierte Relativpositionierung der Längsachsen von Wirbeldorn und Führungsteil bei gleichzeitiger Relativverdrehung zwischen dem Wirbeldorn und dem Führungsteil ermöglichen,
• - Zuführung des Wirbeldorns zum Werkstück von der ersten Seite der Durchgangsbohrung aus und Zuführung des Führungsteils von der gegenüberliegenden Seite aus, wobei das Werkstück, der Wirbeldorn und das Führungsteil zunächst zumindest näherungsweise konzentrisch zueinander angeordnet sind,
• - Verfahren des Wirbeldorns in radialer Richtung und Zusammenführen der Ausrichtkonturen von Wirbeldorn und Führungsteil, wobei ein Führungsabschnitt des Führungsteils in der Durchgangsbohrung geführt, das heißt in Radialrichtung abgestützt, wird,
• - spanabhebende Herstellung des Innengewindes durch Vorschieben der Anordnung aus Wirbeldorn und Führungsteil durch die Durchgangsbohrung, wobei hierbei keine Axialverschiebung zwischen dem Wirbeldorn und dem Führungsteil auftritt, das Führungsteil nicht rotiert, der Wirbeldorn mit definierter, hoher Drehzahl rotiert und gleichzeitig das Werkstück mit vergleichsweise geringer Drehzahl rotiert.

The process for producing an internal thread by whirling generally comprises the following steps:

• - Provision of a tubular workpiece, i.e. one with a through hole, to be provided with the internal thread,
• - Clamping the workpiece using a center drive spindle of a machine tool so that the through hole is accessible from both sides,
• - Provision of a swivel mandrel and an elongated guide part, wherein alignment contours are formed on the front sides of the swivel mandrel and the guide part, which enable a defined relative positioning of the longitudinal axes of the swivel mandrel and the guide part with simultaneous relative rotation between the swivel mandrel and the guide part,
• - feeding the whirling mandrel to the workpiece from the first side of the through hole and feeding the guide part from the opposite side, whereby the workpiece, the whirling mandrel and the guide part are initially arranged at least approximately concentrically to one another,
• - moving the whirling mandrel in the radial direction and merging the alignment contours of the whirling mandrel and the guide part, whereby a guide section of the guide part is guided in the through hole, i.e. supported in the radial direction,
• - machining of the internal thread by pushing the assembly forward from mandrel and guide part through the through hole, whereby no axial displacement occurs between the whirling mandrel and the guide part, the guide part does not rotate, the whirling mandrel rotates at a defined, high speed and at the same time the workpiece rotates at a comparatively low speed.

During whirling, i.e. machining, the whirling mandrel and the workpiece can either rotate in the same direction, for example both clockwise, or in opposite directions. The functionality of a center drive spindle can also be taken over by a finishing machine in which the workpiece is firmly clamped, while the rotation axis of the tool and the alignment contour of the guide part are moved circularly in a consistent manner.

The method according to the application can be used, for example, to produce an internal thread on a nut of a screw drive. In the simplest case, the screw drive is a simple motion thread. Otherwise, the screw drive can be designed in particular as a rolling screw drive. This means that raceways for rolling elements, in particular balls of a ball screw drive, are produced by whirling.

• 1 ausschnittsweise eine Vorrichtung zum Wirbeln eines Innengewindes,
• 2 Komponenten der Vorrichtung nach 1 in einer Positionierung vor Beginn des Zerspanungsvorgangs, das heißt des Gewindewirbelns.

An embodiment of the invention is explained in more detail below with reference to a drawing. In the drawing:

• 1 detail of a device for whirling an internal thread,
• 2 Components of the device according to 1 in a positioning before the start of the machining process, i.e. thread whirling.

A production machine, identified overall by the reference number 1, is designed as a machine tool with a center drive. This means that a tubular workpiece 2 can be machined from both sides. The production machine 1 is used as a device for whirling an internal thread 3. Regarding the production technology of thread whirling in general, reference is made to the prior art cited at the beginning.

A whirling mandrel 4 of the device 1 comprises a cutting head 5 and a shaft 6. The cutting head 5 is generally referred to as a cutting tool. In the present case, the cutting head 5 is connected in one piece to the shaft 6. Alternatively, the cutting tool 5 could be in the form of cutting plates, for example, which are attached directly or indirectly to the shaft 6. The central axis of the whirling mandrel 4 including the cutting head 5 is designated MA4.

Furthermore, the device 1, i.e. the manufacturing machine for internal thread whirling, includes a rod-shaped guide part 7. At the end of the guide part 7 there is a cylindrical guide section 8 with a larger diameter than the rest of the guide part 7. The diameter of the guide section 8 corresponds approximately to the inner diameter of the workpiece 2. The shaft of the guide part 7 is designated with 9. If the guide part 7 is inserted into the workpiece 2, as in the configuration according to 1 If this is the case, an annular gap is formed between the outer peripheral surface of the shaft 9 and the inner peripheral surface of the workpiece 2, designated 10. The workpiece 2 is supported by the guide section 8 which rests against the inner peripheral surface 10. The central axis of the guide part 7, designated MA7, coincides with the central axis of the workpiece 2 in this state.

The machining process carried out with the production machine 1 for producing the internal thread 3 is particularly characterized by the fact that the whirling mandrel 4 and the guide part 7 are introduced into the workpiece 2 from opposite sides, which is both 1 as well as from 2 In the 2 In the configuration shown, which shows a preparatory step for thread whirling, the whirling mandrel 4 is located centrally in the workpiece 2. A slightly eccentric arrangement of the whirling mandrel 4 would also be possible in this phase, as long as the cutting head 5 does not touch the inner circumferential surface 10. The whirling mandrel 4 is, based on the arrangement according to 2 , shifted from right to left. Axial displacements of the vertebral spine 4 are generally designated AV4.

The whirling mandrel 4 has a pin 11 that projects beyond the cutting head 5 and, in conjunction with a recess 12 designed as a blind hole on the front side of the guide section 8, represents a means for aligning the whirling mandrel 4 in relation to the guide part 7. The recess 12 is located eccentrically in the guide section 8. In order to be able to insert the pin 11 into the recess 12, the originally existing radial offset between the pin 11 and the recess 12 must be eliminated. This is done by a radial displacement of the whirling mandrel 4, designated RV4.

The machining of the internal thread 3 can be carried out either from right to left or from left to right, based on the arrangements according to the 1 and 2 , while During the machining process, the axial displacement of the guide part 7 designated AV7 corresponds to the axial displacement AV4 of the whirling mandrel 4. This means that the axial distance between the guide section 8 and the cutting head 5 does not change during whirling. Likewise, the guide part 7 including the guide section 8 remains in an unchanged angular position during thread whirling. During whirling, the whirling mandrel 4 including the cutting head 5 performs a rapid rotation RS. At the same time, a relatively slow rotation RW of the workpiece 2 takes place, which is coordinated with the axial displacements AV4 and AV7.

list of reference symbols

1

production machine

2

workpiece

3

internal thread

4

vertebral spine

5

cutting head, cutting tool

6

shaft of the vertebral spine

7

guide part

8

leadership section

9

shaft of the guide part

10

inner peripheral surface

11

cones

12

recess, blind hole

AV4

axial displacement of the vertebral mandrel

AV7

axial displacement of the guide part

MA4

central axis of the vertebral spine

MA7

center axis of the guide part

RS

rotation of the cutting head

RV4

radial displacement of the vertebral spine

RW

rotation of the workpiece

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP 1 820 592 A2 [0002]
• DE 199 22 891 C2 [0004]
• DE 1 280 638 A [0005]
• DE 10 2011 110 131 B4 [0006]

Claims (10)

Device for whirling an internal thread (3), with a whirling mandrel (4) on which a cutting tool (5) provided for producing the internal thread (3) is located, and with an elongated guide part (7) supporting the whirling mandrel (4), at the end of which a guide section (8) is formed, which is provided as a section with a diameter increased in relation to the adjacent region of the guide part (7) for contacting an inner peripheral surface (10) of a workpiece, wherein the whirling mandrel (4) is arranged eccentrically to the guide section (8), characterized in that the whirling mandrel (4) is arranged opposite the guide part (7), wherein means (11, 12) for aligning the whirling mandrel (4) in relation to the guide part (7) are formed on the end faces of the whirling mandrel (4) and of the guide section (8). device according to claim 1 , characterized in that the cutting tool (5) is designed in the form of a cutting head as an integral component of the whirling mandrel (4). device according to claim 1 , characterized in that the cutting tool (5) is in the form of at least one exchangeable cutting plate fastened to the whirling mandrel (4). device according to claim 1 , characterized in that the cutting tool (5) as a cutting head is detachably connected to a shaft (6) of the whirling mandrel (4). Device according to one of the Claims 1 until 4 , characterized in that the means (11, 12) for aligning the swivel mandrel (4) in relation to the guide part (7) are present as a pin (11) of one of the two parts, swivel mandrel (4) and guide part (7), which engages in a front-side bore (12) of the other part (7, 4). device according to claim 5 , characterized in that the pin (11) is located on the swivel mandrel (4). device according to claim 5 , characterized in that the pin (11) is formed by the guide part (7). Method for whirling an internal thread (3), with the following steps: - provision of a tubular workpiece (2), i.e. one having a through-hole, - clamping of the workpiece (2) by means of a central drive spindle of a machine tool, so that the through-hole is accessible from both sides, - provision of a whirling mandrel (4) and an elongated guide part (7), wherein alignment contours (11, 12) are formed on the front sides of the whirling mandrel (4) and the guide part (7), which enable a defined relative positioning of the longitudinal axes (MA4, MA7) of the whirling mandrel (4) and the guide part (7) with simultaneous relative rotation between the said parts (4, 7), - feeding the whirling mandrel (4) to the workpiece (2) from the first side of the through-hole and feeding the guide part (7) from the opposite side, wherein the workpiece (2), the whirling mandrel (4) and the Guide part (7) are initially arranged concentrically to one another, - moving the whirling mandrel (4) in the radial direction and bringing together the alignment contours (11, 12) of the whirling mandrel (4) and guide part (7), wherein a guide section (8) of the guide part (7) is guided in the through hole, i.e. supported in the radial direction, - machining the internal thread (3) by pushing the arrangement of whirling mandrel (4) and guide part (7) forward through the through hole, wherein the guide part (7) does not rotate, the whirling mandrel (4) rotates at a defined, high speed and the workpiece (2) rotates at a comparatively low speed. procedure according to claim 8 , characterized in that the whirling mandrel (4) and the workpiece (2) rotate in opposite directions. procedure according to claim 8 or 9 , characterized in that it is used to produce an internal thread (3) of a nut of a screw drive.

Images