Tool for machining or finishing threads without cutting and method for manufacturing the tool and threads

Abstract

The present application relates to a tool for machining or finishing a thread without cutting and a method for manufacturing the tool and the thread. A tool for machining or finishing a thread without cutting in or on a workpiece, in particular a ball screw, in particular a thread tap or a thread former, comprises at least one forming region rotatable or rotatable about a tool axis for machining or finishing a thread without cutting, in particular an internal thread, wherein the forming region has a plurality of extrusion lugs protruding or projecting radially outwards away from the tool axis, for machining or finishing the thread by pressing the extrusion lugs into the workpiece surface, wherein the extrusion lugs are arranged continuously along a shaping curve substantially spirally around the tool axis, and wherein the pitch of the shaping curve substantially corresponds to the pitch of the thread to be machined or to be finished, wherein the shaping curve has a helix angle, wherein the profile of at least one extrusion lug is designed so that the spiral machined in an axial section containing the tool axis is at least partially arc-shaped or pointed.

Description

[0001] The invention relates to a tool for chipless machining or finishing of threads, a method for producing the tool and a method for producing threads.

[0002] A ball screw drive is a screw drive with balls inserted between a screw and a nut. When the screw and the nut rotate, the balls roll in the corresponding ball screw channels (or ball screw grooves). Such ball screw channels are usually produced with the aid of grinding strips. The known method is time-consuming. Such ball screws must have a high degree of precision. This high precision can only be achieved if the produced thread can also be measured.

[0003] For measuring such threads, stylus probes are known, for example, from DE 199 47 001 A1, DE 10 2013 015 237 A1 or DE 10 2017 103 954 A1. This type of scanning measurement always has a higher accuracy than optical measurement. In order to use a stylus tester, the line to be measured must have certain features, in particular protruding areas of the surface that may prevent the alignment of the probe to the surface. The stylus tester has a test pointer with a test head. The test pointer is guided along the measuring line. In the case of internal threads, the measuring line runs in particular parallel to the thread axis.

[0004] According to the prior art, thread taps for machining or finishing threads without cutting are known. In the case of such tools, the thread is machined without cutting by means of shaping the workpiece, in the form of so-called pressing ridges (Drückstolle), also called molded wedges or teeth, which cold-form the workpiece by pressure. Such pressing ridges have side edges. The advantage of these tools is that the hardness of the material in the area of ​​the thread profile is increased by deformation of the surface and the associated hardening, thereby producing a more wear-resistant thread than threads machined by cutting.

[0005] Known thread taps, in particular thread taps for machining internal threads, comprise a shank and a working area. The shank is usually cylindrical and is received and held in a chuck of a thread machining device with its end facing away from the workpiece. The working area, in particular the forming area, is located on the side of the thread tap opposite the shank.

[0006] The forming area is provided with a forming curve spirally surrounding along the circumferential direction, and the extruded flange is formed as a protrusion along the forming curve.

[0007] In the thread tap known from DE 10 2012 100 734 A1, the pitch angle between two extrusion flanges that are respectively consecutive along the shaping curve is of the same size for all extrusion flanges. The connecting line of the imaginary straight lines between the tips of the extrusion flanges along the shaping curve forms (except for radial deviations) a substantially regular n-gon (n-polygon) in the projection onto a surface perpendicular to the tool axis, wherein the n extrusion flanges of each turn of the shaping curve are arranged around the tool axis. Every n-th extrusion flange is arranged along a straight line parallel to the tool axis. These straightly arranged extrusion flanges form a so-called extrusion ridge. In addition, thread taps with different pitch angles are also known from DE 10 2012 100 734 A1.

[0008] In known thread taps, the extrusion flange has a profile that is determined perpendicularly to the shaping curve. In particular, the extrusion flange has a triangular, elliptical or cylindrical profile in the upper region of the extrusion flange. Such a profile is perpendicular to the direction of the shaping curve. The section perpendicular to the shaping curve is also called the normal section. In a shaping curve with a thread pitch, this means that the profile in the normal section is inclined by a helix angle (Steigungswinkel) α relative to the plane (axial section) that includes the axis of rotation of the thread tap. The plane containing the axis of rotation (axial section plane) is the rz plane in the cylindrical coordinate system. The helix angle α is located in the θ-z plane, where θ is the angular coordinate of the coordinate system. At α=0°, the curve has no pitch (Steigung), but is a rotation perpendicular to the axis of rotation. α=90° corresponds to the direction of the axis of rotation.

[0009] This profile cannot be measured with sufficient accuracy using known stylus instruments. In particular, in known thread taps, in particular those designed as polygons, the profile along the extrusion lug cannot be measured with sufficient accuracy.

[0010] The object of the present invention is to provide a tool for machining or finishing threads without cutting, which has a higher precision. Another object of the present invention is to provide a method for machining threads, which can be measured more accurately with a stylus instrument, and to provide a method for producing a threading tool, which is used to produce such a thread.

[0011] In terms of the tool, the object is achieved by a tool according to the invention for machining or finishing a thread in or on a workpiece without cutting, in particular a tool for machining or finishing a ball screw without cutting, the tool being in particular a thread tap or a thread former, the tool comprising at least one forming region rotatable or rotating about a tool axis for machining or finishing a thread without cutting, in particular an internal thread. The forming region has a plurality of extrusion lugs protruding or projecting radially outward away from the tool axis for machining or finishing the thread by pressing the extrusion lugs into the workpiece surface. The extrusion lugs are arranged continuously along a shaping curve that surrounds the tool axis in a substantially spiral shape. The pitch of the shaping curve substantially corresponds to the pitch of the thread to be machined or to be finished, wherein the shaping curve has a helix angle α. According to the invention, the profile of at least one extrusion lug is designed so that the spiral (Gewindegang) machined in an axial section containing the tool axis is at least partially circular or pointed. The section including the axis of rotation of the thread tap is an axial section. In a profile curve with a thread pitch, this means that the profile in the normal section is inclined by a helix angle α relative to a plane (axial section) that includes the axis of rotation of the thread tap. Preferably, the profiles of a plurality of or all of the extrusion lugs are designed in this way. Due to the rounded or pointed shape, the surface in the axial section can be better reached with a test head and the measuring accuracy is increased.

[0012] In particular, a circular arc is to be understood as a cylindrical shape, an ellipse or a convex shape with a varying radius. In particular, a sharp arc is to be understood as a Gothic arc shape with a uniform or variable radius. The tip (Spitze) of the sharp arc can be rounded. In the design solution, the variable radius can be a profile having different sections with different radii (e.g., two to five different radii), and in particular, the profile has transition regions between different sections, so that the curvature changes from a first radius to a second radius.

[0013] In the design, the profile of at least one first extruded flange is at least partially arc-shaped or pointed, in particular completely arc-shaped or pointed, in an axial section containing the tool axis. In particular, the radially outer region of the first extruded flange, advantageously the region containing the tip of the extruded flange, has an arc-shaped or pointed profile. In particular, the profile is one of the following: arc-shaped, pointed, pointed with rounded ends, pointed with a first radius in the tip region and a second radius in the side edge region, pointed with extended legs. Two extruded flanges adjacent in the axial section can be separated by a groove. Such a groove can be implemented in particular as flat or concave in the axial section.

[0014] In another design, the tool comprises in particular two or three or four or five or six or more extrusion flanges, and / or the extrusion flanges are arranged in at least two extrusion ridges. In the sense of the present invention, such an extrusion ridge is composed of a plurality of extrusion flanges. Here, in particular, it is a straight extrusion ridge, wherein every n-th extrusion flange is arranged along a straight line parallel to the tool axis, i.e., arranged at an angle of 360°. In particular, the first extrusion flange is arranged in an extrusion ridge. An extrusion ridge having a plurality of first extrusion flanges, in particular having only first extrusion flanges in the forming area, is a first extrusion ridge. Therefore, the first extrusion flange has a circular arc or pointed arc profile in an axial cross section, in particular in the area containing the tip of the extrusion flange. In this design, the tool along the tool axis, in particular along the profile of the tip of the extrusion flange, can be measured particularly well using a stylus instrument.

[0015] Subsequently, the shape of the helix to be machined can be calculated exactly by geometric conversion, or the corresponding contour in the axial section can be calculated from the shape of the thread to be machined and the required contour in the normal section.

[0016] Optionally, one of the extrusion ridges along the shaping curve is longer than the other extrusion ridges, wherein in particular the longer extrusion ridge (the second extrusion ridge) has a length of 1.5 to 2.5 times the sweep angle θ compared to the shorter extrusion ridge (in particular the first extrusion ridge). Therefore, in an advantageous design, the longer extrusion ridge substantially corresponds to two adjacent extrusion ridges without a lubrication groove located therebetween.

[0017] In particular, the longer second extrusion ridge can be an extrusion ridge with a plurality of second extrusion flanges, in particular with only second extrusion flanges in the forming area. In particular, the tool comprises exactly one second extrusion ridge and a plurality of first extrusion ridges. Advantageously, the first extrusion ridge and the second extrusion ridge have similar or identical profiles.

[0018] In one embodiment, the tool has at least one, in particular a plurality of cooling channels, which in particular each have an outlet opening in a shank-side section of the forming region.

[0019] In another embodiment, at least a portion of the extruded lugs, in particular the first extruded lug and / or the second extruded lug, has a slotted region and / or a clearance region. In the slotted region, the height of the extruded lug increases in the radial direction, and in the clearance region, the height of the extruded lug decreases in the radial direction, so that a clearance is present. The slotted region is located in front of the tip of the extruded lug along the shaping curve in the direction of rotation. The clearance region is located behind the tip of the extruded lug in the direction of rotation.

[0020] The slotted area and / or the clearance area can follow a polygonal course. The slotted area transitions into the area of ​​the extruded lug tip by means of a transition area, and / or the area of ​​the extruded lug tip transitions into the clearance area by means of another transition area. In particular, the slotted area can have a slotting angle in the range of 5° to 17°, in particular a slotting angle of 12°.

[0021] In a design solution, the forming area includes a forming area and a calibration area, wherein the forming curve in the forming area has particularly one to three turns, and the forming curve in the calibration area has particularly two to twenty turns, preferably five to ten turns. In another design solution, the calibration area can be designed as a cone, so that the diameter of the calibration area increases toward the handle. For example, the taper ratio can be 1:1000.

[0022] The method according to the invention for machining or finishing a thread (in particular a ball screw, preferably an internal thread) without cutting can be used to machine a thread with a tool according to the invention, wherein the thread comprises a thread pitch with a helix angle α and is suitable for scanning with a known stylus instrument. The method according to the invention has the advantage that the thread can have a high degree of precision and can be manufactured with less time consumption.

[0023] In one embodiment, the spiral machined in a cross section containing the tool axis is at least partially circular or pointed, in particular cylindrical.

[0024] In this design, the thread is first pre-cut and then finish-formed.

[0025] The method according to the invention is suitable for producing a tool according to the invention for machining or finishing a thread in or on a workpiece without cutting, in particular for machining or finishing a ball screw without cutting, the tool being in particular a thread tap or a thread former. In this case, the method comprises in particular the following steps: providing a blank and milling out or cutting an extruded lug, or providing a shank and constructing the extruded lug using an additive method, in particular 3D printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following is a more detailed description of other features and advantages of the present invention based on the description of the embodiments and with reference to the accompanying drawings. In the accompanying drawings:

[0027] Figure 1 A view showing an embodiment of a thread tap according to the present invention;

[0028] Figure 2 Shows Figure 1 Another view of an embodiment of a thread tap;

[0029] Figure 3 Shows Figure 1A view of an embodiment of a tip of a thread tap;

[0030] Figure 4 The profile of the extruded flange along the forming curve is shown;

[0031] Figure 5 The thread profile is shown;

[0032] Figure 6 shows the superposition of the profiles of the extruded flange in the axial section and the normal section;

[0033] Figure 7a , Figure 7b , Figure 7c Various sharp arc profiles of extruded flanges are shown, and

[0034] Figure 8a , Figure 8b Various sharp arc profiles of the extruded flange are shown.

[0035] Figure 1 The thread tap 1 in the embodiment of the present invention has a shank 2 and a forming region 5. The shank is at least partially cylindrical and has a quadrilateral profile at the end facing away from the forming region 5, which is suitable for being received in a chuck of a threading device. The thread tap has a tool axis A, which is the axis of rotation.

[0036] The forming area 5 is divided into a forming area 3 facing the tool tip and a calibration area 4. In the forming area 5, the extrusion flange 7 is arranged in the extrusion ridges 9, 10. The extrusion ridges 9, 10 are straight extrusion ridges. The extrusion flange 7 is located on a spiral forming curve (Formgebungskurve) 6, which has a helix angle α. Here, the extrusion flange 7 has a greater radial height in the calibration area 4 than in the forming area 3. The lubrication groove 11 is arranged accordingly between two adjacent extrusion ridges 9, 10. The extrusion ridges 9, 10 and the lubrication groove 11 extend parallel to the tool axis A.

[0037] Adjacent extrusion flanges 7 in extrusion ridges 9 and 10 are not directly adjacent to each other, but are separated from each other by grooves 14, which are implemented flat in the axial section in the embodiment shown. Here, groove 14 extends parallel to the shaping curve 6. Extrusion flange 7 has a profile 20 parallel to the tool axis, i.e., the profile in the axial section. The profile 20 is defined by a profile boundary curve 21a in the direction of the tool axis. The two profile boundary curves of adjacent extrusion flanges 7 do not intersect here, but terminate at the groove 14 accordingly. In a section perpendicular to the shaping curve 6 (i.e., a normal section), the same extrusion ridge has different profile boundary curves 21b when the helix angle is not equal to zero. In an alternative embodiment (not shown), adjacent extrusion flanges can also be adjacent to each other without grooves, or separated by means of a groove that tapers toward the shank axis (i.e., a concave shape). In the first case, the corresponding profile boundary curves terminate at the intersection position or the transition portion toward the concave groove.

[0038] As in Figure 2 In particular Figure 3 As can be seen in FIG. 1 , the extrusion ridges 9 and 10 have different lengths. Figure 3 In the view of the tool tip in , the thread tap 1 has a polygonal shape, here with five corners. Each extrusion ridge 9 comprises a polygonal corner. The extrusion ridge 9 with the extrusion flanges 7a and 7c has a first length and comprises exactly one polygonal corner respectively. This relates to a first extrusion ridge 9 with first extrusion flanges 7a, 7c. The extrusion ridge 10 with the extrusion flange 7b has a greater length and comprises two polygonal corners. This relates to a second extrusion ridge 10 with a second extrusion flange 7b. The area of ​​the polygonal corners of each extrusion flange constitutes an extrusion flange tip 8, which has a radial distance from the tool axis A that is greater than the remaining area of ​​the extrusion flange. The second extrusion flange 7b has extrusion flange tips 8a and 8b, wherein the extrusion flange tip 8a is located behind the extrusion flange tip 8b on the shaping curve. The extrusion flange tips 8a and 8b can have different radial distances from the tool axis.

[0039] like Figure 4 As shown in , the shorter first extruded flange 7a and / or the longer second extruded flange 7b having the slotted area 15 and the back angle area 16 particularly have a first slotted angle δ. A transition area is formed toward the polygonal angle. The extruded flange tip 8 has a curved area or a smooth area along the shaping curve 6, and has a cylindrical profile in a plane inclined by α relative to the vertical plane (i.e., an axial section), so it is a circular arc profile here, and transitions to a back angle area with a back angle ξ via another transition area. In the example, the back angle ξ here substantially corresponds to the slotted angle δ, in particular to a slotted angle of ±5°.

[0040] Figure 5 A thread profile 30 is shown, in which a helix 31 winds along a profile curve 6. In a normal section N, ie in a view inclined by a helix angle α relative to an axial section, the thread profile shown has a circular arc-shaped profile, in particular a cylindrical profile.

[0041] Figure 6 8 show further contours of the extrusion lug, in particular further contours of the extrusion lug in the region of the extrusion lug tip, in a normal section or in an axial section. Figure 6 A second design of the profile of the extruded flange overlapping in the normal section and the axial section is shown. The arc K serves only as a visual aid and simplifies the identification of the radius changing along the profile boundary curves 21a and 21b. The profile boundary curve 21a represents the profile boundary curve in the axial section, while the profile boundary curve 21b represents the profile boundary curve in the normal section. Both profile boundary curves 21a, 21b are designed as sharp arcs. The two profile boundary curves 21a, 21b differ in the lower area facing the corresponding groove 14. Figure 7a shows a sharp arc profile in axial section, while Figure 7b A sharp arcuate profile with rounded tips in axial cross section is shown. Figure 7c Another pointed arc profile is shown in axial section, wherein, in contrast to the previously shown profiles, the radius is the radius R1 in the region facing the respective groove 14 and transitions to the radius R2 in the region of the pointed arc tip, wherein R1 <R2。

[0042] Figure 8a and Figure 8b Another embodiment of the extruded flange profile is shown, in particular another embodiment of the extruded flange profile in the region of the extruded flange tip. Figure 8a The two legs of the pointed arc have a uniform radius here. Figure 8b In the embodiment of the present invention, the radius of the leg increases in the region facing the groove 14, so that the leg is extended tangentially.

[0043] Reference Mark List

[0044] 1 Tools

[0045] 2 Handle

[0046] 3. Finalizing area

[0047] 4 Calibration Area

[0048] 5 Forming area

[0049] 6. Shaping curve

[0050] 7 Extrusion flange

[0051] 7a, 7c First extrusion flange

[0052] 7b Second extrusion flange

[0053] 8 Extruded flange tip

[0054] 9 First extrusion ridge

[0055] 10 Second compression ridge

[0056] 11 Lubrication groove

[0057] 12 Cooling channels

[0058] 14 slots

[0059] 15 Slotted area

[0060] 16 Rear corner area

[0061] 20 Outline

[0062] 21a First contour boundary curve

[0063] 21b Second contour boundary curve

[0064] 30 Thread profile

[0065] 31 Spiral

[0066] A Tool axis

[0067] N Normal section plane

[0068] α Helix angle

[0069] δ Slot angle

[0070] ξ Back angle

[0071] θ Angle of cylindrical coordinate system

[0072] K Arc.

Claims

1. A tool (1) for machining or finishing a thread in or on a workpiece without cutting, the tool (1) comprising at least one profiled region (5) rotatable about a tool axis (A) for machining or finishing a thread without cutting, in, The forming area (5) has a plurality of extrusion flanges (7, 7a, 7b, 7c) protruding or extending radially outward away from the tool axis (A), and is used for machining or finishing threads by pressing the extrusion flanges (7, 7a, 7b, 7c) into the workpiece surface. wherein the extrusion flanges (7, 7a, 7b, 7c) are arranged continuously along a shaping curve (6) spirally surrounding the tool axis (A), and The pitch of the shaping curve (6) corresponds to the pitch of the thread to be processed or finished. Wherein, the shaping curve has a helix angle (α), It is characterized in that In an axial section containing the tool axis (A), the profile of at least one extrusion flange (7, 7a, 7b, 7c) is at least partially arc-shaped or pointed, wherein the extrusion flange (7, 7a, 7b, 7c) is arranged in at least two extrusion ridges (9, 10), and wherein one of the at least two extrusion ridges (9, 10) is a first extrusion ridge (9), and the other extrusion ridge is a second extrusion ridge (10), wherein the second extrusion ridge (10) is longer than the first extrusion ridge (9) along the shaping curve (6), and wherein the second extrusion ridge (10) has a length of 1.5 to 2.5 times the sweep angle (θ) compared to the first extrusion ridge (9).

2. The tool (1) according to claim 1, wherein: The tool (1) is used for chip-free machining or finishing of a ball screw in or on a workpiece.

3. The tool (1) according to claim 1, wherein: The tool (1) is a thread tap or a thread former.

4. The tool (1) according to claim 1, wherein: The tool (1) is used for chip-free machining or finishing of internal threads.

5. The tool (1) according to any one of claims 1 to 4, wherein: In an axial section containing the tool axis (A), the contour of the at least one extrusion lug in the region of the extrusion lug tip (8) is arc-shaped or pointed.

6. The tool (1) according to any one of claims 1 to 4, wherein: In an axial section containing the tool axis (A), the contour of the at least one extrusion bead in the region of the extrusion bead tip (8) is cylindrical.

7. The tool (1) according to claim 5, wherein: The profile of one or more extrusion flanges (7, 7a, 7b, 7c) is selected from one of the following profiles: a circular arc and a sharp arc.

8. The tool (1) according to claim 5, wherein: The profiles of all the extruded flanges (7, 7a, 7b, 7c) are selected from one of the following profiles: a circular arc and a sharp arc.

9. The tool (1) according to claim 7, wherein: The arc is a arc with a rounded end, a arc with a first radius in the region of the tip and a second radius in the region of the side edge, or a arc with an extended leg.

10. The tool (1) according to any one of claims 1-4 and 7-9, wherein the tool (1) comprises two or three or four or five or six or more extrusion lugs (7, 7a, 7b, 7c).

11. The tool (1) according to any one of claims 1 to 4 and 7 to 9, wherein: The tool (1) has cooling channels (12) which each have an outlet opening in a shank-side section of the forming region (5).

12. The tool (1) according to claim 5, wherein: At least a portion of the extruded flange (7, 7a, 7b, 7c) has a grooved area (15) and / or a rear angle area (16), wherein in the grooved area, the height of the extruded flange increases in the radial direction, and in the rear angle area, the height of the extruded flange decreases in the radial direction, and wherein the grooved area is located in front of the tip of the extruded flange along the shaping curve in the rotational direction, and the rear angle area is located behind the tip of the extruded flange in the rotational direction.

13. The tool (1) according to claim 12, wherein: The groove region (15) and / or the clearance region (16) have a polygonal shape.

14. The tool (1) according to claim 12 or 13, wherein the groove area (15) transitions into the area of ​​the extruded flange tip (8) by means of a transition area, and / or wherein the area of ​​the extruded flange tip (8) transitions into the rear angle area (16) by means of another transition area.

15. The tool (1) according to any one of claims 1-4, 7-9 and 12-13, wherein the forming area (5) comprises a forming area (3) and a calibration area (4), wherein the forming curve in the forming area (3) has one to three turns, and the forming curve in the calibration area (4) has two to twenty turns.

16. The tool (1) according to claim 15, wherein The shaping curve in the calibration area (4) has five to ten turns.

17. The tool (1) according to claim 15, wherein The calibration area is conical.

18. A method for chipless machining or finishing of a thread using a tool (1) according to any one of the preceding claims, wherein the thread comprises a pitch with a helix angle (α), in, The spiral machined in a cross section containing the tool axis is at least partially circular or pointed.

19. The method according to claim 18, wherein: The threads are pre-cut and subsequently finish-formed.

20. A method for producing a tool (1) for chipless machining or finishing of a thread in or on a workpiece according to any one of claims 1 to 17, wherein the method is selected from: a) providing a blank and milling or cutting the extruded flange; b) Providing a handle and constructing the extruded flange using an additive method.

21. The method according to claim 20, wherein: The additive method is 3D printing.

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