END-PROFILING MACHINE, METHOD FOR END-PROFILING A THREAD, AND FASTENING MEANS

Description

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/EP 2023/081320, filed Nov. 9, 2023, which claims the benefit of and priority to German Patent Application No. DE 10 2022 130 066.8, filed Nov. 14, 2022, the contents of which are hereby incorporated herein by reference in their entireties.

TECHNICAL FIELD

The invention relates to an end profiling machine, a method for end profiling a thread and a fastening means.

BACKGROUND

The threads of screws, especially high-strength or ultra-high-strength screws, cannot usually be produced in a single rolling process, as the forces required for this are usually so high that this can or would lead to damage or even destruction of the rolling tool. For this reason, the threads of screws, especially high-strength or ultra-high-strength screws, are first pre-rolled or pre-profiled before they are hardened and tempered if necessary and then end-profiled in order to form the final thread. However, the problem with this end profiling of the thread is that the end area of the thread or the thread run-out is not end-profiled. This ultimately leads to this thread area having mechanically poorer properties than the final profiled area and/or being more susceptible to hydrogen embrittlement.

SUMMARY

It is therefore the object of the invention to provide a way of manufacturing or providing a fastening means, in particular a screw, which fulfills high mechanical requirements in a wide range of the thread and/or has particularly positive properties in the thread area with regard to hydrogen embrittlement.

This object is solved with an end profiling machine according to claim 1, with a use of an end profiling tool according to claim 10, a use of a sensor or a sensor arrangement according to claim 11, with a method for end profiling a thread according to claim 12 and/or with a fastening means according to claim 14. Further advantages, features or embodiments are apparent from the sub-claims, the description and/or the figures.

According to the invention is an end profiling machine, wherein the end profiling machine is in particular a thread rolling device. The end profiling machine advantageously has at least two, preferably at least three, end profiling tools and/or a sensor arrangement. The sensor arrangement comprises at least one sensor, wherein the end profiling machine is an infeed or throughfeed profiling machine, in particular in a tool feed direction, wherein the end profiling tools are advantageously designed to end profile a thread pre-profile of a blank, wherein at least the one sensor is designed such that it detects when the end profiling tools reach or approach the thread outlet of the thread pre-profile of the blank. The end profiling machine is therefore in particular a machine which serves to form a profile by means of forming, wherein the end profiling machine is advantageously a thread rolling device. In other words, the end profiling machine can be used to end profile a thread by forming. In particular, end profiling can be understood as the end rolling of a thread. To achieve this end rolling or end profiling, in particular by rolling a thread, the end profiling machine has at least two end profiling tools. These end profiling tools are the forming tools for profiling. In particular, these forming tools or end profiling tools can represent or form the profile part of the end profiling tools. In other words, the end profiling tool is formed precisely by those components of the end profiling tool which are in engagement with the workpiece during the end profiling process or during the thread rolling process in order to final profile or final roll an already existing pre-profile, in particular a thread pre-profile, of a blank by forming. The end profiling tools can be moved relative to each other. This relative movement can be both a transatlantic movement and a rotational movement. Preferably, the rotational relative movement is in the tool feed direction. Alternatively, the movement of the end profiling tools can be an absolute movement rather than a relative movement. In particular, the translational movement can also be at least partially parallel to the tool feed direction. The end rolling is advantageously carried out after tempering, in particular of the pre-profiled blank. The end rolling or end profiling of a thread is therefore the actual thread production process. The entire thread is therefore produced in at least two stages, with the thread pre-profile having a smaller profile depth than that of the standard thread or final thread. The end profiling, which as already explained can also be carried out as end rolling, is then performed in such a way that the depth of the pre-profile thread is increased to the finished thread profile depth. The deformation of the thread during end profiling or end rolling is sufficient to establish internal stresses in the thread root and thus generate positive mechanical properties. In addition, such end profiling or end rolling of the thread can have a positive effect on the material with regard to hydrogen embrittlement. The end profiling tools can in particular be rollers and/or dies. These end profiling tools of the end profiling machine are in particular aligned and/or arranged in such a way that—by moving the end profiling tools relative to each other—a running-in and/or running-through of the workpiece or blank to be profiled is achieved. In other words, the relative movement of the end profiling tools relative to one another can cause the blank to enter or pass between or into the gap between the end profiling tools. In other words, the end profiling machine can therefore be an infeed or throughfeed profiling machine. This infeed direction is in particular the tool feed direction. Expediently, the tool feed direction is oriented parallel to the longitudinal axis of the blank or workpiece. Alternatively, an infeed profiling machine can preferably be understood in the sense of the invention to mean that the workpiece or the blank is accelerated or moved in a translation direction by the relative movement of the end profiling tools. This direction of translation is, in particular, the tool feed direction; in particular, the workpiece or the blank is pulled or moved between the profiling tools. In addition to the end profiling tools, which are driven automatically in particular, the end profiling machine also has a sensor arrangement. This sensor arrangement comprises at least one sensor, preferably a plurality of sensors. At least one of the sensors, preferably a plurality of sensors of the sensor arrangement, is or are designed in such a way that it or they detect when the end profiling tools reach the thread outlet of the thread profile of the blank or approach it. Reaching is understood to mean that all thread crests or thread teeth of the thread have been contacted by the end profiling tool or one of the end profiling tools both on one flank and on the opposite flank, which are thus arranged in particular in a positive tool feed direction and/or in their negative tool feed direction in relation to the thread crest or thread tooth. Approaching means that the closest contact of one or all end profiling tools with the blank and/or the minimum distance of the end profiling tools to each other is at most a distance of three times the pitch of the thread pre-profile, preferably at most once the pitch of the thread pre-profile, particularly preferably a maximum of 0.2 times the pitch of the thread pre-profile, particularly strongly preferred a maximum of 0.1 times the pitch of the thread pre-profile, and even more particularly strongly preferred a maximum of 0.05 times the pitch of the thread pre-profile from the thread outlet. The thread run-out is the run-out of the thread, wherein the thread run-out forms in particular the end of the thread which is not a free end. In other words, in the case of a screw, for example, the thread run-out is the end of the thread that faces the head. Alternatively or additionally preferably, the thread run-out can form the transition between the shank and the thread facing away from the thread or form the end of the thread oriented in this direction. The sensor-based detection of the reaching or approaching of the thread run-out of the thread pre-profile by the end profiling tools can thus be used to detect that the rolling process must be ended or should be ended soon. For this purpose, at least one of the sensors can be a displacement measuring sensor and/or a force sensor.

Preferably, the end profiling tools are rollers, in particular two rollers or three rollers. In other words, the end profiling machine can be a two-roller end profiling machine or a three-roller end profiling machine. By designing the machine in this way, a particularly simple configuration of an infeed or throughfeed principle or an infeed or throughfeed profiling machine can be achieved.

Alternatively, the end profiling tools can preferably be rolling dies, in particular two rolling dies. By designing the end profiling tools as rolling dies, a particularly simple and cost-effective end profiling machine can be achieved.

Advantageously, at least one of the sensors is an optical sensor or a non-contact sensor and/or wherein at least one of the sensors is a mechanical sensor. An optical sensor can, for example, be formed by a laser or a light barrier. The advantage of optical sensors is that they can result in a particularly low-wear design. If one of the sensors is designed as a mechanical sensor, the approaching or reaching of the thread run-out of the thread profile can be reliably detected, especially with high levels of soiling. A mechanical sensor can be a load cell, for example. Alternatively or additionally, the sensors can also be non-contact sensors, in particular capacitive or inductive sensors. These sensors are also particularly low-wear.

Advantageously, at least one of the sensors is a displacement measuring sensor. In other words, for example, the sensor can be designed to measure the position of the blank or the workpiece in the tool feed direction. Therefore, if a sufficient distance or displacement in the tool feed direction is achieved during the infeed or throughfeed profiling process, the approach or reaching of the thread run-out of the thread pre-profile of the blank can also be detected. Such a displacement measuring sensor can be achieved, for example, by a laser, a capacitive and/or an inductive sensor. Alternatively or additionally preferably, the displacement measuring sensor can not only interact with the blank by measurement, but can be arranged in such a way that it detects a movement of the end profiling tool or end profiling tools. In other words, the sensor can therefore indirectly detect the approach or reaching of the thread run-out by the end profiling tools via the tool movement. Advantageously, however, the sensors, in particular the displacement measurement sensors, interact directly with a blank by measurement. In other words, at least one of the sensors, advantageously a displacement measuring sensor, is arranged in such a way that it interacts or can interact by measurement with a blank arranged between the end profiling tools.

Preferably, at least one of the sensors is a force sensor, wherein the force sensor measures in particular a force perpendicular to the tool feed direction. Such a force sensor can be realized, for example, by a load cell or a strain gauge. The principle of a sensor for signaling a force for detecting the reaching and/or approaching of the thread run-out of the pre-profile of the blank is based on the fact that the thread depth of the thread pre-profile decreases sharply in the thread run-out, so that the forming forces acting on the end profiling tools increase sharply. Advantageously, the force sensor measures a force perpendicular to the tool feed direction. This is a particularly simple and reliable realization of a force-based detection of reaching or approaching the thread run-out.

Preferably, the end profiling machine has a control unit, wherein the control unit stops and/or opens and/or separates the or one of the end profiling tools depending on a sensor signal from the at least one sensor of the sensor unit. Stopping means that the control unit stops the end profiling tool in its relative movement with respect to the other end profiling tool or in its absolute movement. Separating or opening means that an increasing distance is created between the end profiling tools so that the end profiling tools perform a relative movement or a distancing from one another, in particular perpendicular to the tool feed direction, during separation or opening. This relative movement, in particular the distancing movement, removes the blank or the workpiece, in particular from the space between the end profiling tools, in particular by utilizing gravity and/or an automatic machine of the end profiling machine. In other words, when the end profiling tools are opened, the blank or the workpiece can fall out of the end profiling machine. Alternatively, a reverse rotation of the workpiece/blank can also be initiated, in particular by the end profiling tool, in order to remove the workpiece.

Advantageously, the end profiling tools are designed to form a metric thread or another standard thread, in particular an inch thread. In other words, a metric thread can be profiled or end-rolled or end-profiled with the end-profiling machine. This allows the end profiling machine to be used for a particularly wide range of applications.

Advantageously, the end profiling tools are designed for end profiling a thread in a high-strength or ultra-high-strength material. In other words, the end profiling tools can be designed in such a way that they are able to carry out end profiling or end rolling even in high-strength or ultra-high-strength materials. This can be achieved in particular by suitable hardening of the end profiling tools. A high-strength material is in particular a material whose tensile limit or tensile strength is at least 800 N/mm², preferably at least 1000 N/mm². An ultra-high-strength material, on the other hand, has a tensile limit or tensile strength of at least 1200 N/mm², preferably at least 1400 N/mm². The possibility of end profiling or end rolling high-strength or ultra-high-strength materials using the end profiling tools and therefore also using the end profiling machine makes it particularly suitable for the production of screws in strength classes 8.8, 10.9, 12.9 or even 14.8 or 14.9, 15.8U, 15.9U or higher.

A further aspect of the invention may relate to a method for end profiling a thread. However, the features disclosed in connection with the method can also be part of the end profiling machine, in particular as device features. Conversely, however, a device feature of the end profiling machine can also be provided as a process feature in the method for end profiling a thread. The method for end profiling of a thread can therefore be carried out in particular using an end profiling machine as described above and below. The method for end profiling of a thread comprises in particular the steps:

• • Providing a blank, wherein the blank has a thread pre-profile with a thread outlet;
  • bringing the blank into contact with at least two end profiling tools, in particular end profiling tools of the end profiling machine, wherein the blank is moved or accelerated in a tool feed direction by the movement of at least one end profiling tool, wherein the thread profile is end-profiled by the contact of the blank with the end profiling tools
  • Detecting by means of a sensor, in particular a sensor of a sensor arrangement of the end profiling machine, whether the end profiling tools have reached the thread outlet of the thread pre-profile of the blank or are approaching the thread outlet of the thread pre-profile of the blank.

By moving at least one end profiling tool and by bringing the blank into contact with at least two end profiling tools, wherein the movement of at least one end profiling tool moves or accelerates the blank in a tool feed direction, the result is an infeed or throughfeed profiling. In particular, the advantages already described above and below can be achieved by the method for end profiling of a thread.

In an advantageous further development of the process for end profiling of a thread, this has the feature that the blank, at least in the area of the thread pre-profile, consists of or comprises a high-strength or an ultra-high-strength material. In other words, the end profiling machine can thus end profile a thread that is formed in a high-strength or ultra-high-strength material. This makes it particularly suitable for producing screws in high-strength or ultra-high-strength form, in particular in strength classes 8.8, 10.9, 12.9, 14.8 or 14.9 or even in higher strength classes, in particular 14.9 U.

In particular, the thread pre-profile was tempered before the process for end profiling and pre-profiled before tempering. In other words, the invention can thus relate not only to a method for end profiling of a thread, but also to a manufacturing method for a fastening means, in particular a screw.

A further aspect of the invention may relate to a fastening means, in particular a screw. Advantageously, the thread of the fastening means has been produced and/or end-profiled at least in sections, preferably completely, using a method as described above or below. Alternatively, the screw may also have been produced using an end profiling machine as described above and/or below.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and features of the present invention are shown in the following description with reference to the figures. Individual features of the embodiments shown can also be used in other embodiments, unless this has been expressly excluded. It shows:

FIG. 1 an end profiling machine or a section of an end profiling machine, wherein the end profiling tools are open; and

FIG. 2 an end profiling machine, wherein the end profiling tools are brought into contact with the blank.

DETAILED DESCRIPTION

FIG. 1 shows an end profiling machine 1—at least in sections-which has two end profiling tools 10 12. The end profiling tools 10 12 can be flat rolling dies or rollers. The end profiling tools 10 12 are used for end profiling or end rolling a thread pre-profile. By moving one of the end profiling tools 10 12, the tool or the blank 40 can be moved in the tool feed direction L, with the tool feed direction L running parallel and/or coaxially to the longitudinal direction of the blank 40, which can also be referred to as the workpiece. In the situation shown, the end profiling tools 10 12 have already reached the thread outlet 30, so that a control unit of the end profiling machine 1, which is not shown, has stopped, separated and opened the end profiling tool 10 12. In order to detect this approach of the end profiling tools 10 12 to the thread outlet 30 or the reaching of the thread outlet 30, the end profiling machine 1 has a sensor arrangement 20, which in the example shown comprises only one sensor, which in turn is a force transducer.

FIG. 2 shows a further embodiment of an end profiling machine 1, wherein a process step of a process for the end profiling of a thread can also be seen graphically in FIG. 2. The blank 40 has a thread pre-profile 32, which has a thread outlet 30. The blank 40 extends coaxially to the tool feed direction L, wherein the tool feed direction L is the direction in which the blank 40 moves due to the movement of one or both end profiling tools 10 12. The end profiling machine 1 has a sensor arrangement 20 which can detect a force perpendicular to the tool feed direction L by means of a measuring sensor and, in addition, the end profiling machine 1 also has a displacement measuring sensor in its measuring sensor arrangement 20, which is an optical sensor, in particular a laser.

FIG. 3 shows a situation in which the end profiling tools 10, 12 reach or approach the thread outlet 30 of the thread pre-profile 32 of the blank 40. Strictly speaking, therefore, FIG. 3 does not show a blank 40, but a finished part. Basically, the end profiling machine 1 shown in FIG. 3 corresponds or can correspond to the embodiment example in FIG. 2 in a different working position.

LIST OF REFERENCE SIGNS

• • 1—End profiling machine
  • 10,12—End profiling tools
  • 20—Sensor arrangement
  • 30—Thread outlet
  • 32—Thread pre-profile
  • 40—Blank
  • L—Tool feed direction