Method for working a rolling die

Abstract

The invention relates to a method for working a rolling die, in particular a thread rolling die for rolling a thread onto a screw blank. The rolling die has a rolling die surface with a plurality of grooves, and the rolling die surface is being structured.

Description

[0001] Method for machining a rolling die

[0002] Description

[0003] The invention relates to a method for machining a rolling die, a rolling die machined by a method according to the invention, a method for rolling a thread into a screw blank and a screw with a thread, rolled by a method according to the invention, according to the independent patent claims.

[0004] There are state-of-the-art methods for machining a rolling die in which a large number of transverse grooves are created on the rolling dies. These transverse grooves are intended to prevent, for example, a screw from slipping between the rolling dies during rolling.

[0005] However, the rolling surfaces of the dies in the area of ​​these transverse grooves are subjected to significant stress due to the high contact pressure and rolling motion of the screw, causing them to wear very quickly. Thus, the service life of conventional dies is significantly reduced due to wear on the rolling surfaces. Another disadvantage has been found to be the transverse grooves on the screw shaft that create a so-called "tank track structure," which leads to a reduction in the cross-section of the screw shaft and thus a reduction in strength.

[0006] It is therefore the object of the present invention to eliminate the disadvantages of the prior art and in particular to reduce the wear of the rolling dies and to increase the service life of the rolling dies.

[0007] This object is achieved by the subject matter of the independent claims. Advantageous developments of the invention are specified in the subclaims. The scope of the invention also includes all combinations of at least two of the features specified in the description, the claims, and / or the figures. Within the specified value ranges, values ​​within the stated limits are also intended to be disclosed as limit values ​​and claimable in any combination.

[0008] The invention relates to a method for machining a rolling die, in particular a rolling die for rolling a thread into a screw blank, comprising a rolling die surface with a plurality of grooves, in particular for rolling the thread, wherein the rolling die surface is structured.

[0009] The invention further relates to a rolling die machined by a method according to the invention.

[0010] The invention further relates to a device for rolling a thread into a screw blank, comprising at least one rolling die, machined by a method according to the invention.

[0011] The invention further relates to a method for rolling a thread into a screw blank, wherein the thread is rolled using a device or method according to the present invention. The invention further relates to a screw with a thread, wherein the thread is rolled using a method according to the present invention.

[0012] By structuring the surface of the rolling die, it is advantageously possible for the rolling surfaces of the rolling dies to be subjected to relatively low loads, even under high contact pressure during the rolling movement of a workpiece, especially a screw, so that the rolling die is subject to less wear. Thus, the service life of the rolling die can be extended thanks to the wear-resistant surface of the rolling die.

[0013] For the further description of the invention, it is clarified that the grooves in the rolling die surface do not constitute the produced structure. The produced structure is created in addition to the grooves on the rolling die surface, particularly in areas between adjacent grooves.

[0014] In addition, the cross-section of the workpiece, in particular of the screw shaft, is advantageously not reduced at all or at least hardly reduced, so that a higher strength is achieved than in the prior art.

[0015] This can further advantageously improve the quality of the workpieces produced, in particular the screws, and increase the service life of the rolling dies.

[0016] The structuring advantageously provides for a relatively rough and hard surface. In particular, alloy components can be evaporated by the laser radiation, so that a greater hardness is achieved on the surface when the components harden. The mean roughness Ra achieved by the structuring is preferably between Ra 3 and Ra 30; in particular, thinner screws (diameters from 1.6 mm to 4.5 mm) have a mean roughness of Ra 3 to Ra 15, and thicker screws (diameters from 4.6 mm to 16 mm) have a mean roughness of Ra 16 to Ra 30.

[0017] The structure created on the rolling die surface has a multitude of elevations and depressions.

[0018] According to an advantageous embodiment of the invention, it is provided that the rolling die surface is structured by laser radiation.

[0019] According to another preferred embodiment, it is provided that the rolling die surface is structured by machining, in particular by a milling cutter and / or by grinding.

[0020] According to another preferred embodiment, a leather-like surface is created. A leather-like surface is defined by having a plurality of irregular elevations and depressions.

[0021] Particularly when structuring with a laser, it is advantageous to achieve a relatively rough and hard surface. In particular, the surface is melted and the desired roughness is thereby created, so that, for example, the workpiece, in particular the screw blank, is prevented from slipping, so that, for example, the thread can be formed cleanly. According to another preferred embodiment, provision is made for a stepped structure to be created. This is particularly designed such that a large number of steps are created on the rolling die surface. These steps can in particular be arranged transversely to the direction of extension of the grooves. The grooves are usually arranged parallel to one another and extend parallel to a main direction of extension.

[0022] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings, each of which shows a schematic view:

[0023] Figure 1 shows an exemplary embodiment of a device according to the invention,

[0024] Figure 2a shows a first exemplary embodiment of a rolling die according to the invention,

[0025] Figure 2b shows a second exemplary embodiment of a rolling die according to the invention,

[0026] Figure 3 shows an enlarged section of the rolling die surface of the rolling die from Figure 2a.

[0027] In the figures, advantages and features of the invention are identified by reference numerals identifying them in accordance with embodiments of the invention, wherein components or features with the same or equivalent function are identified by identical reference numerals.

[0028] Figure 1 schematically shows an exemplary embodiment of a device 8 according to the invention. The device 8 according to the invention for rolling a thread into a screw blank 5 has two rolling dies 1 according to the invention. One rolling die 1 remains stationary, while the other rolling die 1 is designed to be movable and can move in the direction of the arrows indicated on the rolling die 1.

[0029] The rolling dies 1 have a plurality of grooves 2 on their rolling die surface 6. Furthermore, the rolling die surface 6 is structured.

[0030] In this embodiment, the device 8 comprises two rolling dies 1, each having a plurality of grooves 2 arranged parallel to one another and producing a thread in the screw blank 5. The grooves 2 extend parallel to a main direction of extension.

[0031] The rolling die surface 6 has been structured, in particular by laser radiation. In this embodiment, the rolling die surface 6 has a leather-like surface 7.

[0032] The leather-structure-like surface 7 has a plurality of elevations and depressions arranged next to one another.

[0033] The operation of device 8 is briefly described below. In principle, the operation of such a device is known to those skilled in the art.

[0034] The movable rolling die shown is pulled backwards in an idle stroke (to the left in the picture) and takes the blank 5, which is pushed forward by an insert slide 4, forwards (to the right in the picture).

[0035] In a rolling motion between the fixed and movable rolling dies 1, the thread (not shown) is rolled onto the blank 5. The penetration of the rolling die into the blank causes the displaced material to be formed into the tool contour. Figure 2a schematically shows a first exemplary embodiment of a rolling die 1 according to the invention. The rolling die 1 has a rolling die surface 6. The rolling die surface 6 has a plurality of grooves 2.

[0036] The grooves 2 are arranged parallel to each other and create a thread in a screw blank. The grooves 2 extend parallel to a main extension direction.

[0037] According to the invention, the rolling die surface 6 has been structured, in particular by laser radiation. In this embodiment, the rolling die surface 6 has a leather-like surface 7.

[0038] The leather-structure-like surface 7 has a plurality of elevations and depressions arranged next to one another.

[0039] Figure 2b schematically shows a second exemplary embodiment of a rolling die 1' according to the invention. The rolling die surface 6 has a plurality of grooves 2; to avoid repetition, reference is made to the explanations for Figure 2a.

[0040] In this embodiment, the rolling die surface has a step structure 7'.

[0041] The rolling die surface has a plurality of step-like formations that run transversely between two adjacent grooves 2.

[0042] In this embodiment, the dimensions of the steps decrease over time and therefore become smaller.

[0043] The stepped structure is created, for example, by a laser. Figure 3 shows a schematic enlarged view of section A of Figure 2a. This view shows the leather-like surface 7 of the rolling die surface 6 in detail. A multitude of elevations and depressions arranged next to one another can be seen.

[0044] The embodiments described above serve only to illustrate the invention and do not limit the basic inventive concept in any way.

[0045] List of reference symbols , 1 ' rolling die groove feed rail insert slide screw blank rolling die surface ,7' structure device for rolling

Claims

Patent claims 1. Method for machining a rolling die (1, 1'), in particular a rolling die (1, 1') for rolling a thread into a screw blank (5), comprising a rolling die surface (6) with a plurality of grooves (2), in particular for rolling the thread, characterized in that the rolling die surface (6) is structured.

2. Method according to claim 1, wherein the rolling die surface (6) is structured by laser radiation.

3. Method according to claim 1, wherein the rolling die surface (6) is structured by machining, in particular by a milling cutter and / or by grinding.

4. Method according to at least one of the preceding claims, wherein a leather-structure-like surface (7) is produced.

5. Method according to at least one of the preceding claims, wherein a step structure (7') is produced.

6. Rolling die (1, 1') machined by a method according to at least one of the preceding claims.

7. Device (8) for rolling a thread into a screw blank (5), comprising at least one rolling die (1, 1'), machined by a method according to at least one of the preceding claims.

8. A method for rolling a thread into a screw blank (5), wherein the thread is rolled with a device according to the preceding claim.

9. A screw having a thread, wherein the thread is rolled by a method according to the preceding claim.

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