TOOL FOR CHIPLESS PRODUCTION OR FINISHING OF A THREAD, METHOD FOR PRODUCING THE TOOL AND METHOD FOR PRODUCING A THREAD

Abstract

A tool for the chipless production of a thread in a workpiece comprises at least one shaping region which can be rotated about a tool axis (A) for the chipless production or finishing of the thread. The shaping region comprises a plurality of pressing lobes projecting radially outwardly from the tool axis (A) for producing the thread by pressing the pressing lobes into the workpiece surface. The pressing lobes are successively arranged along a forming curve which substantially spirals around the tool axis (A), and the pitch of the forming curve essentially corresponds to the pitch of the thread to be produced or reworked. The forming curve has a helix angle (a), and a profile of at least one pressing lobe is designed in such a way that a thread produced in an axial section containing the tool axis is at least in sections round-arched or ogival.

Claims

1. A tool for the chipless production or finishing of a thread, in particular a ball thread, in or on a workpiece, in particular a cold forming tab or thread former, comprising: at least one shaping region which can be rotated or rotated about a tool axis (A) for the chipless production or finishing of the thread, in particular an internal thread, wherein: the shaping region comprises a plurality of pressing lobes projecting or protruding radially outwardly from the tool axis (A) for producing or finishing the thread by pressing the pressing lobes into the workpiece surface, the pressing lobes are successively arranged along a forming curve which substantially spirals around the tool axis (A), the pitch of the forming curve essentially corresponds to the pitch of the thread to be produced or reworked, the forming curve has a helix angle (a); and a profile of at least one pressing lobe is designed in such a way that a thread produced in an axial section containing the tool axis is at least in sections round-arched or ogival.

2. The tool as recited in claim 1, wherein: a profile of at least one pressing lobe is at least in sections round-arched or ogival, in particular cylindrical, in an axial section containing the tool axis (A); and the profile of the at least one pressing lobe is round-arched or ogival, in particular cylindrical, in an axial section containing the tool axis (A) in the region of a pressing lobe tip.

3. The tool as recited in claim 2, wherein: the profile of at least one of the pressing lobes is selected from one of the following profiles: round, ogival, ogival with rounded tip, ogival with a first radius in the region of the tip and a second radius in the region of the flanks, ogival with extended legs.

4. The tool as recited in one of the preceding claims, wherein the tool comprises in particular two or three or four or five or six or more pressing lobes and/or wherein the pressing lobes are arranged in at least two pressing ridges.

5. The tool as recited in claim 4, wherein: one of the at least two pressing ridges is a first pressing ridge and another is a second pressing ridge; the second pressing ridge is longer along the forming curve than the first pressing ridge or webs; and the second pressing ridge has in particular the length of a 1.5-2.5 times swept angle θ than the shorter first pressing ridges.

6. The tool as recited in claim 1, wherein the tool has cooling channels, each cooling channel having an outlet opening in a shaft-side section of the shaping region.

7. The tool as recited in claim 1, wherein: at least some of the pressing lobes have an initial forming region and/or have a free surface region; and optionally the initial forming region and/or free surface region has a polygonal shape.

8. The tool as recited in claim 7, wherein: the initial forming region passes into the region of the pressing lobe tip by means of a transition region; and/or the region of the pressing lobe tip passes by a further transition region to the free surface region.

9. The tool as recited in claim 1, wherein: the shaping region comprises a forming region and a calibrating region; the forming curve in the forming region has in particular one to three revolutions; and the forming curve in the calibrating region has in particular two to twenty, preferably five to ten revolutions and wherein in particular the calibrating region is conical.

10. A method for the non-cutting production or reworking of a thread, in particular a ball thread, preferably an internal thread, comprising: using a tool for the chipless production or finishing of a thread, in particular a ball thread, in or on a workpiece, in particular a cold forming tab or thread former, comprising: rotating at least one shaping region about a tool axis (A) for the chipless production or finishing of the thread, in particular an internal thread, wherein the shaping region comprises a plurality of pressing lobes projecting or protruding radially outwardly from the tool axis (A) for producing or finishing the thread by pressing the pressing lobes into the workpiece surface; arranging the pressing lobes successively along a forming curve which substantially spirals around the tool axis (A), wherein the pitch of the forming curve essentially corresponds to the pitch of the thread to be produced or reworked, and the forming curve has a helix angle (a); designing a profile of at least one pressing lobe such that a thread produced in an axial section containing the tool axis is at least in sections round-arched or ogival; and scanning the thread with a stylus instrument, wherein the thread has a thread pitch with the helix angle (a).

11. The method as recited in claim 10, wherein a thread produced in a cut containing the tool axis is at least in sections round or ogival in shape.

12. The method as recited in claim 10, wherein the thread is pre-cut and then re-formed.

13. The method as recited in claim 10, further comprising: providing a blank; and milling or cutting the pressing lobes.

14. The method as recited in claim 10, further comprising: providing a shaft; and building up the pressing lobes with an additive process, especially 3-D printing.

15. A method for the non-cutting production or reworking of a thread, in particular a ball thread, preferably an internal thread, comprising: using a tool for the chipless production or finishing of a thread, in particular a ball thread, in or on a workpiece, in particular a cold forming tab or thread former, comprising: rotating at least one shaping region about a tool axis (A) for the chipless production or finishing of the thread, in particular an internal thread, wherein the shaping region comprises a plurality of pressing lobes projecting or protruding radially outwardly from the tool axis (A) for producing or finishing the thread by pressing the pressing lobes into the workpiece surface; the pressing lobes being arranged successively along a forming curve which substantially spirals around the tool axis (A), wherein the pitch of the forming curve essentially corresponds to the pitch of the thread to be produced or reworked, and the forming curve has a helix angle (a); producing a thread that is at least in sections round-arched or ogival in an axial section containing the tool axis; and scanning the thread with a stylus instrument, wherein the thread has a thread pitch with the helix angle (a).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention is also explained in more detail below with regard to further features and advantages by means of the description of embodiments and with reference to the enclosed drawings. Thereby show

[0028] FIG. 1 a view of an embodiment of a thread tap according to the invention,

[0029] FIG. 2 another view of the execution example from FIG. 1 of the thread tap,

[0030] FIG. 3 a view of the execution example from FIG. 1 on a tip of the thread cutter,

[0031] FIG. 4 the profile of a pressing lobe along the forming curve,

[0032] FIG. 5 a thread profile

[0033] FIG. 6 a superposition of a profile of a pressing lobe in axial and normal section

[0034] FIG. 7 a, b, c different ogival profiles of a pressing lobe, and

[0035] FIG. 8 a, b different ogival profiles of a pressing lobe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The cold forming tab 1 in FIG. 1 has a shank 2 and a forming region 5. The shank is cylindrical at least in sections and has a square profile at an end facing away from forming region 5, which is suitable for mounting in a chuck of a thread generating device. The cold forming tab has a tool axis A, which is the axis of rotation.

[0037] The shaping region 5 is divided into a forming region 3 facing a tool tip and a calibrating region 4. In shaping region 5, pressing lobes 7 are arranged in pressing ridges 9, 10. The pressing ridges 9, 10 are straight pressing ridges. The pressing lobes 7 lie on a spiral forming curve 6, which has a helix angle α. In the calibration region 4, the pressing lobes 7 have a greater radial height than in the forming region 3. A lubrication groove 11 is arranged between two adjacent pressing ridges 9, 10. The pressing ridges 9, 10 and the lubrication grooves 11 run parallel to a tool axis A.

[0038] Adjacent pressing lobes 7 in a pressing ridge 9, 10 do not abut directly but are separated from each other by a groove 14, which is flat in the axial section in the embodiment shown. Here, the groove 14 runs parallel to the forming curve 6. A pressing lobe 7 has a profile 20 parallel to the tool axis, i.e. a profile in the axial section. This profile 20 is limited in the direction of the tool axis by a profile limiting curve 21a. Two profile boundary curves of adjacent pressing lobes 7 do not meet here, but each end at the groove 14. In a section perpendicular to the forming curve 6, i.e. normal section, the same pressing ridge has a different profile boundary curve 21b at an helix angle not equal to zero. In an alternative embodiment not shown, adjacent pressing lobes can also abut without a groove, or be separated by a concave groove tapering towards the shaft axis. In the first case, the respective profile boundary curves then end at the joint or at the transition to the concave groove.

[0039] As shown in FIG. 2 and especially FIG. 3, the pressing ridges 9, 10 have a different length. In the view of the tool tip in FIG. 3, the cold forming tab 1 has a polygonal shape, here with five corners. Each of the pressing ridge 9 has a polygon corner. The pressing ridges 9 with the pressing lobes 7a and 7c have a first length and each comprise exactly one polygon corner. These are first pressing ridges 9 with first pressing ridges 7a, 7c. The pressing ridge 10 with the pressing lobes 7b has a greater length and includes two polygon corners. It is a second pressing ridge 10 with second pressing lobes 7b. The region of the polygon corner of each pressing lobe forms a pressing lobe tip 8, which has a greater radial distance to the tool axis A than the other regions of the pressing lobe. The second press lobe 7b has press lobe tips 8a and 8b, with the press lobe tip 8a on the forming curve behind the press lobe tip 8b. The pressing lobe tips 8a and 8b can have different radial distances to the tool axis.

[0040] The shorter first pressing lobe 7a and/or the longer second pressing lobe 7b with a initial forming region 15 and an free surface region 16, as shown in FIG. 4, has in particular a forming edge angle δ. A transition region is formed towards the polygon corner. The apex of the pressing lobe 8 has a curved or smooth region along the forming curve 6 and in a plane tilted around a to the vertical plane, i.e. in the axial section, a cylindrical profile, thus here a round arch profile, and passes over a further transition region into an free surface region with a clearance angle ξ. In this example, the clearance angle ξ essentially corresponds to the clearance angle δ, especially the clearance angle ±5°.

[0041] FIG. 5 shows a thread profile 30, with thread 31 winding along the forming curve 6. In the normal section N, i.e. in a view tilted by the pitch angle α to the axis section, the thread profile shown has a round arc-shaped profile, especially a cylindrical profile.

[0042] FIGS. 6 to 8 show further profiles of a pressing lobe, especially in the region of a pressing lobe tip, in normal cut or axial cut. FIG. 6 shows a second embodiment of a profile of a pressing lobe in an overlapping of normal section and axial section. The circular arc K serves only as a visual support and simplifies the recognition of the changing radius along the profile boundary curves 21a and 21b. Profile boundary curve 21a represents the profile boundary curve in the axis section, while profile boundary curve 21b represents the profile boundary curve in the normal section. Both profile boundary curves 21a, 21b are ogival. The two profile boundary curves 21a, 21b differ in a lower region facing the respective groove 14. FIG. 7a shows an ogival profile in axial section, while FIG. 7b shows an ogival profile in axial section with rounded tip. FIG. 7c shows a further ogival profile in axial section, in which, in deviation from the previously shown profiles, the radius in the region facing the respective groove 14 is a radius R1 and which merges into a radius R2 in the region of the tip of the ogival arch, where R1<R2.

[0043] FIGS. 8a and 8b show a further embodiment of a pressing lobe profile, especially in the region of a pressing lobe tip. The two legs of the pointed arch have a uniform radius in FIG. 8a. In FIG. 8b, the radius of the legs increases in an region facing the groove 14, so that the legs are tangentially extended.

TABLE-US-00001 Reference character list  1 Tool  2 Shaft  3 forming region  4 Calibration region  5 shaping region  6 forming curve  7, Pressing lobes  7a, 7c first pressing lobe  7 b second pressing lobe  8 Pressing lobe tip  9 first pressing ridge 10 second pressing ridge 11 Lubrication groove 12 Cooling channel outlet 14 Groove 15 initial forming region 16 Free surface region 20 Profile 21a first profile boundary curve 21b Second profile boundary curve 30 Thread profile 31 Thread A Tool axis N Normal cutting plane α helix angle δ forming edge angle ζ clearance angle θ angular coordinate of the coordinate system K circular arc