TANGENTIAL THREAD ROLLING HEAD

Abstract

The invention relates to a tangential thread rolling head including two rolling head arms having a thread roll rotatably mounted on an axle. The thread rolls are configured to engage with a gear and be pushed laterally into an assembled position into the rolling head arms before the installation of the axles and the axles can be pushed into a bearing bore hole of the thread rolls. The two thread rolls have identical thread profiles that are offset with respect to each other when the thread rolls are in the assembled position.

Description

CROSS REFERENCE TO RELATED INVENTION

This application is based upon and claims priority to, under relevant sections of 35 U.S.C. §119, European Patent Application No. 16 156 541.1, filed Feb. 19, 2016, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The invention relates to a tangential thread rolling head comprising two fork-like rolling head arms, in each of which a thread roll is rotatably mounted on an axle, wherein the thread rolls respectively engage with a gear coupling the thread rolls, and wherein the thread rolls can be pushed laterally into an assembled position into the rolling head arms before installation of the axles, in which one of the axles can be pushed into a bearing bore hole of a corresponding thread roll.

A tangential thread rolling head is known, for example, from the document EP 0 811 443 B1. This tangential thread rolling head has the advantage that it ensures through the complimentary configuration of interacting catches of thread rolls and pinions of the gear, that the thread rolls can only be installed in the rolling head arms in a single defined rotary position. The tangential thread rolling head known from EP 0 811 443 B1 can have rolling head arms that can be pivoted towards each other. Tangential thread rolling heads with fixed rolling head arms that cannot be pivoted towards each other are also known. For example, SU 654338 A1 shows such a tangential thread rolling head.

The thread rolling or respectively the cylindrical die thread rolling recess process with tangential thread rolling heads occurs through lateral advancement onto the workpiece to be processed up to the middle of the axle and back again. If the workpiece to be processed is located with its axle on the connection line between the rotary axles of the thread rolls, the pitch points on the workpiece would arrive at locations offset by 180°. However, this is not the case at the beginning and end of the rolling process, as will be explained below based on FIGS. 3 and 4. In order to ensure that the thread profile of a thread roll engages exactly in the thread grooves formed by the thread profile of the other thread roll, the thread profiles of the two thread rolls are spatially offset with respect to each other. This spatial offset dimension is imperative for successful processing. Due to the demand of the offset dimension, it is required in the prior art to produce two different thread rolls with thread arrangements that are offset with respect to each other. The production effort is hereby increased. Moreover, a potential interchanging of the thread rolls due to the offset thread profiles in the prior art leads to damage and loss of functionality during processing.

Based on the explained prior art, the object of the invention is to provide a tangential thread rolling head of the initially named type, with which the offset dimension of the thread profiles of the thread rolls required for the processing can be realized in an easier and more reliable manner from a production point of view.

BRIEF SUMMARY OF THE INVENTION

For a tangential thread rolling head of the initially named type, the invention solves the object in that the two thread rolls including a thread profile designed respectively on their circumferential surface are designed identically, in that the thread rolls have roll engagement means, which engage with the gear engagement means of the gear. The roll engagement means and the gear engagement means are configured such that each of the thread rolls can only be pushed laterally into the assembled position, which is a single defined rotary position. The rotary position for the two thread rolls is different such that the thread profiles of the thread rolls are offset with respect to each other in the assembled position.

The tangential thread rolling head according to the invention has, in a generally known manner, two rolling head arms each configured to receive one thread roll. The rolling head arms can be held on a rolling head holder. The two thread rolls are each rotatably mounted on an axle of each thread roll. The rotary axles of the thread rolls run parallel to each other. The thread rolls are joined together via a gear, such as a synchronous gear. The thread rolls can be pushed laterally into the rolling head arms in order to reach the assembled position. In the assembled position, the rotary axles can be pushed into the thread rolls.

According to an embodiment, the thread rolls have roll engagement means, which engage with the gear engagement means of the gear. The roll engagement means and the gear engagement means are configured such that each of the thread rolls can only be pushed laterally into the assembled position in a single defined rotary position, wherein the rotary position for the two thread rolls is different. In the assembled position, the thread profiles of the identically designed thread rolls according to the invention are thus offset with respect to each other. The roll engagement means and the gear engagement means form a geometric shape, which joins the thread rolls with the gear. According to the invention, the geometric shapes of the two thread rolls are twisted with respect to each other, wherein the twist represents the required offset dimension between the thread profiles. The thread rolls and thus the starting points of the thread profiles on the circumferential surfaces of the thread rolls are offset with respect to each other by the required offset dimension in the assembled position. According to the invention, the thread rolls including their thread profile are thereby designed identically. The required offset dimension results automatically and reliably in the course of the installation of the thread rolls in the tangential thread rolling head. The production of the thread rolls is simplified and the operational safety is increased through avoidance of an interchanging of the thread rolls impacting the functionality.

According to a particularly practical design, the roll engagement means can be formed by catches of the thread rolls and the gear engagement means can be formed by catches of pinions of the gear. The catches of the thread rolls engage respective catches of a pinion. The catches of the thread rolls and the catches of the pinions can be configured complementary to each other. The thread rolls can each have a pair of opposite-lying catches and/or the pinions can each have a pair of opposite-lying catches.

According to a particularly practical design, the thread rolls and the pinions can be arranged respectively on a common axle. This design further simplifies the assembly. For inserting the axles, the thread rolls and the pinions can each have bearing bore holes, which are flush with each other in the assembled position of the thread rolls. As explained, the axles run parallel to each other.

According to a further embodiment, the catches of the thread rolls can respectively form at least one stop surface. In the assembled position or state the stop surfaces abut against the catches of the pinions. For example, in the prior art according to EP 0 811 443 B1, the problem is that the complementary acute angles of the catch ends of thread rolls and pinions cannot be designed to be exactly the same size due to unavoidable production tolerances. As a result, the catches of the pinions are designed slightly smaller than the corresponding acute-angled seat formed by the catches of the thread rolls. The thread roll is thereby in turn pushed slightly too far into the pinion when pushed all the way in so that the bearing bore holes of the thread roll and pinion are not exactly flush. In practice, it is then complicated to push the common rotary axle through the pinion and the thread roll. This problem is overcome in the aforementioned design of the invention in that a stop is formed by a defined stop surface and, when reached, the bearing bore holes of the thread roll and pinion are exactly flush with each other. The assembly of the common rotary axle is correspondingly simplified.

The stop surfaces can have a curved progression, for example a circularly curved progression. The stop surfaces can in this case be adjusted for the outer diameter of the pinion. A particularly simple self-centering is achieved in this manner. It is also possible for example that the stop surfaces progress into the assembled position at least in sections diagonal to the insertion direction of the thread rolls.

Furthermore, the stop surfaces can also respectively be formed by a stop section connecting two opposite-lying catch sections of the thread rolls. In this design, it is possible that each thread roll has only one catch. This catch has two opposite-lying catch sections, which are interconnected by the stop section. In contrast, the associated pinion can have two catches.

It can be provided according to a further embodiment that the stop sections each have a smaller thickness than the opposite-lying catch sections so that a seat delimited by the stop surface is formed between the opposite-lying catch sections for a complementarily catch of the associated or corresponding pinion. A pocket-shaped seat is thus formed, delimited laterally by the ends of the opposite-lying catch sections. The floor of the seat is formed by the stop surface of the stop section. A catch of the respectively associated pinion is received in this pocket-shaped seat. According to a further embodiment, the seats of the two thread rolls can have different widths.

According to a further particularly practical design, the pinions and gear wheels of the gear engaging with them are provided with optical markings that show the installation position of the pinions relative to the gear wheels engaging with them. The optical markings can be formed, for example, by dotted or dashed markings applied to the pinions and the associated gear wheels. They show the rotary position of the pinions and gear wheels provided for operating the tangential thread rolling head such that it is ensured in particular that the thread rolls engaging with the pinions are installed in the provided rotary position. It can also be provided that the gear wheels engaging with the pinions and a coupling gear wheel of the gear in turn engaging with it are provided with optical markings, which show the provided installation position of the gear wheels relative to the coupling gear wheel. The optical markings can in turn be formed by (further) dotted or dashed markings applied to the coupling gear wheel and the gear wheels.

As explained, the tangential thread rolling head according to the invention has two rolling head arms, each of which receive one of the thread rolls. It is possible that the rolling head arms are not movable with respect to each other, in particular are not pivotable. It is then a tangential thread rolling head with fixed rolling head arms, which can be designed for example as one piece with a rolling head holder. Specifically in the case of such tangential thread rolling heads with fixed rolling head arms, the invention is particularly advantageous since the thread rolls have a permanently defined position with respect to each other. The respective offset dimension can thus be realized in a particularly reliable manner by the different specified rotary positions of the thread rolls.

However, it is also generally possible that the tangential thread rolling head comprises a rolling head holder, on which the rolling head arms are pivotably mounted on a common axle running parallel to the roll axles. Furthermore, the tangential thread rolling head can then have adjusting means for adjusting the pivot position of the rolling head arms on the rolling head holder.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are explained in more detail in the following using the drawings. They show schematically in:

FIG. 1 illustrates a perspective view of an embodiment of a tangential thread rolling head,

FIG. 2 illustrates a perspective view of an embodiment of a tangential thread rolling head,

FIG. 3 illustrates a schematic representation of the processing of a workpiece in an embodiment of the tangential thread rolling head,

FIG. 4 illustrates a further schematic representation of the processing of a workpiece in the tangential thread rolling head of FIG. 3,

FIG. 5 illustrates a perspective view of an embodiment of a gear of the tangential thread rolling head,

FIG. 6 illustrates a perspective view of an embodiment of a thread roll of a tangential thread rolling head,

FIG. 7 illustrates a perspective view of the pinion of the gear shown in FIG. 5 interacting with the thread roll from FIG. 6,

FIG. 8 is a side view of the pinion of the pinion gear shown in FIG. 5 interacting with the thread roll from FIG. 6, and

FIG. 9 a top plan view of the gear shown in FIG. 5.

If not otherwise specified, the same reference numbers indicate the same objects in the figures.

DETAILED DESCRIPTION OF THE INVENTION

The tangential thread rolling head according to the invention shown in FIG. 1 comprises a rolling head holder 10, on which a first fork-like rolling head arm 12 and a second fork-like rolling head arm 14 are designed as one piece and fixed. In the first rolling head arm 12, a first thread roll 16 is rotatably mounted on an axle 18. In the second rolling head arm 14, a second thread roll 20 is rotatably mounted on an axle 22. The axles 18, 22 run parallel to each other. The basic structure and the function of such a tangential thread rolling head are known and are thus not explained in greater detail.

FIG. 2 shows an alternative form of a tangential thread rolling head according to the invention. This tangential thread rolling head also has two rolling head arms 12′, 14′, in which the first and second thread rolls 16′, 20′ are rotatably mounted on axles 18′, 22′. In turn, the axles 18′, 22′ run parallel to each other. In contrast to the tangential thread rolling head from FIG. 1, the rolling head arms 12′, 14′ in the tangential thread rolling head from FIG. 2 are pivotably mounted on a common axle 24′ running parallel to the roll axles 18′, 22′. Reference number 26′ shows an adjustable spring and thread means are shown (not in greater detail), via which the pivot position of the rolling head arms 12′, 14′ can be adjusted. The design and function of such a tangential thread rolling head with pivotable rolling head arms is also generally known and is thus not explained in greater detail.

Based on FIGS. 3 and 4, the processing of a cylindrical workpiece shown as reference number 28 shall be explained as an example in the tangential thread rolling head in FIG. 1. FIG. 3 shows the beginning of the thread rolling process. The thread rolls 16, 20 and the workpiece 28 are in this case advanced to each other along the infeed direction shown by the arrows 30, until the position shown in FIG. 4 is reached. Thread rolls 16, 20 and workpiece 28 are subsequently moved apart from each other again. In FIG. 4, the first thread roll 16 engages with the workpiece 28 along the contact location 32 and the second thread roll 20 engages with the workpiece 28 along the contact location 34. The contact locations 32, 34 lie offset by 180° with respect to each other at the processing time shown in FIG. 4. At the start of processing, as shown in FIG. 3, these contact locations are not offset by 180°. The theoretical contact location offset by 180° is shown dashed by reference number 36 in FIG. 3. However, the contact of the second thread roll 20 at the start of processing actually takes place at the contact location 34. For this reason, the thread profiles of the thread rolls 16, 20 must be offset with respect to each other by a defined offset dimension, as initially explained.

FIG. 5 shows a gear of a tangential thread rolling head according to the invention, which can be used for example in the tangential thread rolling heads shown in FIGS. 1 and 2. The gear has a first pinion 38, which cogs with a first gear wheel 40. A second pinion 42 cogs with a second gear wheel 44. The first gear wheel 40 and the second gear wheel 44 cog with different gear wheel planes of a central coupling gear wheel 46 that are movable relative to each other. The structure and functionality of such a synchronous gear used in tangential thread rolling heads are generally known.

The uniqueness according to the invention lies in the interaction of the thread rolls with pinions 38, 42. This interaction is explained in greater detail based on FIGS. 6 and 8, here as an example for the thread rolls 16 and 20. This interaction takes place in a corresponding manner for the thread rolls 16′ and 20′. The first thread roll 16 has a hollow-cylindrical projection 48, on which two catches 50, 52 are designed in the shown example. Referring to FIG. 5, the first pinion 38 also has a hollow-cylindrical projection 54, on which two catches 56, 58 are disposed in the shown example. By pushing the first thread roll 16 laterally into the rolling head arm of the tangential thread rolling head, the catches 50, 52 (FIG. 6) of the first thread roll 16 engage with the complementarily designed catches 56, 58 of the first pinion 38, as can be seen in FIG. 7. As shown in FIG. 5, through the complementarily catches 56, 58 or respectively 50, 52 (FIG. 6) the thread roll 16 (FIGS. 6-8) can only engage with the first pinion 38 in a single defined rotary position. In this assembled position of the first thread roll 16, a common rotary axle 60 can be pushed into the bearing bore holes of the first pinion 38 and of the first thread roll 16 defined by the hollow-cylindrical projections 54 or respectively 48, as can be seen in FIG. 8.

The second pinion 42 of the gear shown in FIG. 5 also has a hollow-cylindrical projection 62, which in turn defines a bearing bore hole for a rotary axle. Two catches 64 and 66 are disposed on the hollow-cylindrical projection 62. The catches 64 and 66 are generally identical to the catches 56 and 58 of the first pinion 38. Moreover, the first and second thread rolls 16, 20 of the tangential thread rolling head shown in FIG. 1 are configured identically, including their thread profiles formed on the circumferential surface. The first and second thread rolls 16′, 20′ of the tangential thread rolling head shown in FIG. 2 are also configured identically, including their thread profiles formed on the circumferential surface. However, the second pinion 42 is arranged twisted by a defined angle with respect to the first pinion 38. If the second thread roll 20 with its catches is now brought in its assembled position engaging with the catches 64, 66 of the second pinion 42 just like the first thread roll 16, the thread rolls 16, 20 are also twisted by this defined angle with respect to each other. The thread profiles designed on the circumferential surface of the thread rolls 16, 20 thus have a defined offset with respect to each other such that the starting points of the thread profiles lie apart from each other by a defined offset dimension.

Referring to FIG. 9, in order to ensure the correct installation of the pinions 38, 42 in the correct rotary position, a corresponding marking can be provided on the tangential thread rolling head and on the pinions 38, 42, which is to be appropriately noted by the processor during installation of the pinions 38, 42. This is explained in FIG. 9 based on an example. Dot markings 68, 70 are in this case detected on the pinions 38, 42 as well as the gear wheels 42, 44 engaging with them. These markings 68, 70 display the provided installation position of the pinions 38, 42 and gear wheels 42, 44 with respect to each other. Moreover, the gear wheels 42, 44 have second dot markings 72, which can be brought to overlap correspondingly with dot markings 74 of the coupling gear wheel 46 during the installation of the gear. It is ensured in this manner that the pinions and gear wheels of the gear are combined in the correct rotary position and the thread rolls are thus also inserted in the provided rotary position with the required offset dimension.

REFERENCE LIST

• 10 Rolling head holder
• 12 First rolling head arm
• 12′ First rolling head arm
• 14 Second rolling head arm
• 14′ Second rolling head arm
• 16 First thread roll
• 16′ First thread roll
• 18 Axle
• 18′ Axle
• 20 Second thread roll
• 20′ Second thread roll
• 22 Axle
• 22′ Axle
• 24′ Axle
• 26′ Adjustable spring
• 28 Cylindrical workpiece
• 30 Arrows
• 32 Contact location
• 34 Contact location
• 36 Theoretical contact location
• 38 First pinion
• 40 First gear wheel
• 42 Second pinion
• 44 Second gear wheel
• 46 Coupling gear wheel
• 48 Hollow-cylindrical projection
• 50 Catch
• 52 Catch
• 54 Hollow-cylindrical projection
• 56 Catch
• 58 Catch
• 60 Rotary axle
• 62 Hollow-cylindrical projection
• 64 Catch
• 66 Catch
• 68 Dot marking
• 70 Dot marking
• 72 Dot marking
• 74 Dot marking

Claims

1. A tangential thread rolling head comprising:

two thread roll arms;

two thread rolls having identical circumferentially disposed thread profiles, each thread roll defining a bearing bore hole and configured to be rotatably mounted on an axle, wherein each thread roll engages a gear coupling the thread roll and can be pushed laterally into an assembled position into the rolling head arms before installation of the axle, and wherein one of the axles can be pushed into the bearing bore hole of a thread roll; and

a roll engagement means configured to engage a gear engagement means of the gear, the roll engagement means and the gear engagement means configured to only allow the two thread rolls to be installed in a single defined rotary position, wherein the single defined rotary position of the two thread rolls offsets the identical circumferentially disposed thread profiles with respect to each other.

2. The tangential thread rolling head according to claim 1, wherein the roll engagement means are formed by catches of the thread rolls and the gear engagement means are formed by catches of pinions of the gear.

3. The tangential thread rolling head according to claim 2, wherein the catches of the thread rolls and the catches of the pinions are complementary to each other.

4. The tangential thread rolling head according to claim 2, wherein the thread rolls and the pinions are disposed on a common axle.

5. The tangential thread rolling head according to claim 2, wherein the catches of the thread rolls each form at least one stop surface, wherein the at least one stop surface abuts the catches of the pinions in the assembled position.

6. The tangential thread rolling head according to claim 5, wherein the at least one stop surface is formed by a stop section connecting two opposite-lying catch sections of the thread rolls.

7. The tangential thread rolling head according to claim 6, wherein each stop section has a smaller thickness than the opposite-lying catch sections so that a seat delimited by the stop surface is formed between the opposite-lying catch sections and configured to engage a complementarily catch of a corresponding pinion.

8. The tangential thread rolling head according to claim 7, wherein the pinions and corresponding gear wheels of an engaging gear include optical markings configured show a proper installation position of the pinions relative to the gear wheels engaging them.

9. The tangential thread rolling head according to claim 1, wherein the two rolling head arms are not movable relative to each other.