Press and method for optimizing a lead screw and nut mechanism of a press

Abstract

The invention relates to a press (1) which comprises a lead screw and nut mechanism (2), a drive unit (3), a press frame (4), an upper punch (5), and a lower punch (6), wherein the lead screw and nut mechanism (2) comprises a lead screw (7) and a nut (8), all of the thread turns of the lead screw (7) are machined such that each of the flank bases of the turns has a continuous concave curvature in a longitudinal sectional view of the lead screw (7), and all of the thread turns of the nut (8) are machined such that each of their flank bases has a continuous concave curvature in a longitudinal sectional view of the nut (8). The invention additionally relates to a method for optimizing a lead screw and nut mechanism.

Description

[0001] "Press and method for optimizing a spindle drive of a press" The invention relates to a press and a method for optimizing a spindle drive of a press according to the preamble of claim 1 and 6 respectively.

[0002] The spindle drive of a press shown in Figure 1 is known as state of the art.

[0003] The object of the invention is to optimize a press with respect to the peak loads to which a spindle and / or a nut of a spindle drive of the press is subjected under tensile or compressive load. Furthermore, the object of the invention is to propose a method by which it is possible to optimize an existing spindle drive of a press with respect to the peak loads to which a spindle and / or a nut of a spindle drive of the press is subjected under tensile or compressive load.

[0004] This object is achieved on the basis of the features of the preamble of claim 1 and 6 by the characterizing features of claim 1 and 6, respectively. Advantageous and expedient developments are specified in the respective subclaims.

[0005] The press according to the invention comprises a spindle drive, a drive unit, a press frame, an upper punch and a lower punch, wherein the spindle drive comprises a spindle and a nut, wherein the spindle can be rotated by the drive unit in a left-hand or right-hand direction and in a right-hand direction.is arranged fixedly in the axial direction, wherein the nut is arranged so as to be movable upwards and downwards in the axial direction on the press part and is non-rotatable, wherein the spindle comprises a multi-start external thread, wherein the nut comprises a multi-start internal thread, wherein the external thread and the internal thread are adapted to one another in such a way that the nut moves upwards or downwards when the spindle rotates, depending on the direction of rotation, wherein all threads of the spindle are machined in such a way that their flank bottoms, viewed in a longitudinal section of the spindle, each have a continuously concave curvature, and wherein all threads of the nut are machined in such a way that their flank bottoms, viewed in a longitudinal section of the nut, each have a continuously concave curvature.Measurements have shown that, in comparison with a press having a spindle drive as shown in Figure 1, - the maximum stresses occurring when the nut is subjected to compressive stress are reduced by approximately 20%, the compressive stress on the nut occurring when the upper punch is lowered.

[0006] - the maximum stresses occurring during a tensile load on the nut are reduced by approximately 30%, whereby the tensile load on the nut occurs when the upper punch is lifted;

[0007] - the maximum stresses occurring during a compressive load on the spindle are improved by up to 3%, whereby the compressive load occurs when the upper punch is lowered and

[0008] - the maximum stresses occurring when the spindle is subjected to a tensile load are reduced by approximately 10%, whereby the tensile load on the spindle occurs when the upper punch is lifted.

[0009] These reduced maximum loads on the spindle and nut result in a longer service life for the spindle drive. Furthermore, each flank base of the spindle is designed to run along a curve in the longitudinal section, starting from a lower flank and ending at the center of the flank base, with the curve having a constant radius. This better directs the forces acting on the lower flank when the nut is lifted in the direction of the spindle's longitudinal axis, significantly reducing the maximum loads.

[0010] With regard to the nut, a course is also provided in which each flank base of the nut runs on a curve in the longitudinal section from an upper flank to a lower flank, with the radius of the curve decreasing gradually or continuously. This means that the nut with the lower flank is suitable for absorbing compressive forces in a closing direction of the press while avoiding notch effects. This means that the upper flank is suitable for transmitting compressive forces in an opening direction of the press while avoiding notch effects. This also means that the flank base is optimally connected with regard to the changing loads occurring when the spindle is lowered and raised.

[0011] It is also provided that a maximum radial distance between a tooth flank of the spindle and the flank base of the nut, viewed in the longitudinal section, is at least 50% and in particular at least 70% of a maximum radial distance between a tooth flank of the nut and the flank base of the spindle. This improves the transmission of the forces acting on the tooth flanks of the nut during lowering and lifting in the direction of the core of the nut, so that the maximum stresses that occur are reduced. Finally, it is provided that the maximum radial distance between the tooth flank of the spindle and the flank base of the nut is at least 10% and in particular at least 15% of a tooth depth of the nut. This enables a correspondingly rounded design of the flank base of the nut.

[0012] The method according to the invention provides for the optimization of a

[0013] Spindle drive of a press, which comprises a spindle and a nut, the following steps: machining of all threads of the spindle in such a way that a maximum radial tooth depth of the spindle measured in a longitudinal section is increased and

[0014] - a machining of all threads of the nut in such a way that a maximum radial

[0015] Tooth depth of the nut is increased. Measurements have shown that with a press with the design shown in Figure 1.

[0016] Spindle drive, in which this spindle drive has been machined accordingly - the maximum stresses occurring when the nut is subjected to compressive load are reduced by approximately 20%, whereby the compressive load on the nut occurs when the upper punch is lowered;

[0017] ~ the maximum stresses occurring under tensile load on the nut are reduced by about 30%, whereby the

[0018] Tensile load on the nut occurs when the upper punch is lifted;

[0019] - the maximum stresses occurring during a compressive load on the spindle are improved by up to 3%, whereby the compressive load occurs when the upper punch is lowered and

[0020] - the maximum stresses occurring when the spindle is subjected to a tensile load are reduced by approximately 10%, whereby the tensile load on the spindle occurs when the upper punch is lifted.

[0021] From these reduced maximum loads on the spindle and the

[0022] Mother results in a longer life expectancy of the spindle drive machined or reworked in this way,

[0023] It is also intended to increase the maximum radial tooth depth of the

[0024] The nut should be enlarged by at least 10% and, in particular, by at least 15%. This reduces the maximum stresses occurring in the area of ​​the flank ends of the nut.

[0025] Furthermore, it is intended to increase the maximum radial tooth depth of the spindle by at least 2% and in particular by at least 5%. This will reduce the maximum stresses occurring in the area of ​​the flank bases of the spindle. < '

[0026] It is also intended to machine the flank bases of the spindle in such a way that after machining - viewed in the longitudinal section - they each have a continuously concave ; have a camber. This type of design also reduces the maximum stresses that occur in the area of ​​the spindle flanks.

[0027] Furthermore, it is intended to machine the flank bases of the nut in such a way that after machining they are in the

[0028] Viewed in longitudinal section, each exhibits a continuous concave curvature. Also, by producing this type of shape, the maximum stresses occurring in the area of ​​the flank bases of the nut are reduced.

[0029] It is also intended to carry out the processing in such a way that

[0030] - viewed in the longitudinal section - a maximum radial distance between a tooth flank of the spindle and the flank base of the nut is increased by at least 50% and in particular by at least 70% of a maximum radial distance between a tooth flank of the nut and the flank base of the spindle. This allows the transmission of the forces acting on the tooth flanks of the nut during lowering and lifting.

[0031] Improve forces towards the core of the nut so that the maximum stresses that occur are reduced.

[0032] Finally, it is intended that the machining is carried out in such a way that the maximum radial distance between the

[0033] Tooth flank of the spindle and the flank bottom of the nut

[0034] At least 10% and in particular at least 15% of the tooth depth of the nut. This allows a correspondingly rounded design of the flank base of the nut,

[0035] For the purposes of the invention, a longitudinal section of a spindle is understood to be a section defined by a sectional plane along which the spindle's rotational axis runs. For the purposes of the invention, a longitudinal section of a nut is understood to be a section defined by a sectional plane along which the nut's axis runs.

[0036] Further details of the invention are described in the drawing using schematically illustrated embodiments.

[0037] This shows: Figure 1: a detailed section through a spindle drive of a state-of-the-art press;

[0038] Figure 2: a press according to the invention in sectional view; - Figure 3: a sectional view of the nut shown in Figure 2 with the spindle accommodated therein;

[0039] Figure 4 : a side view of the one shown in Figure 2 ,

[0040] spindle;

[0041] Figure 5: a sectional view of the spindle shown in Figures 2, 3 and 4;

[0042] Figure 6 : a detailed section of the one shown in Figure 2

[0043] Locker 1 drove s; Figure 7a: a detailed section corresponding to Figure 6 for comparison with Figure 7b;

[0044] Figure 7b: a detailed section corresponding to Figure 1 through a spindle drive according to the state of the art - for comparison with Figure 7a.

[0045] In Figures 1, 6, 7a and 7b, cut surfaces are shown without hatching to keep the representations clearer.

[0046] Figure 1 shows a detailed section through a spindle drive ST of a press P (not shown in detail) which corresponds to the prior art. The spindle drive ST shows a spindle S and a nut M which interacts with it. The non-rotatably arranged nut M is moved upwards in the direction of arrow y when the spindle S rotates clockwise about its axis of rotation DS and downwards in the direction of arrow y' when the spindle S rotates anticlockwise about its axis of rotation DS. The axis of rotation DS is not shown in exact position in Figure 1, but only schematically.

[0047] 2 shows a sectional side view of a press 1 according to the invention. The press 1 comprises a spindle drive 2, a drive unit 3 (only partially shown), a press frame 4, an upper punch 5 and a lower punch 6. The spindle drive 2 comprises a spindle 7 and a nut 8. The spindle 7 can be rotated about its axis of rotation D7 in a left-hand rotation LL or a right-hand rotation RL by the drive unit 3 and is mounted on the press frame 4 in a fixed manner in the axial direction y, y '. The nut 8 can be moved upwards y and downwards y ' in the axial direction on the press frame 4 and is arranged non-rotatably about its axis A8. The nut 8 is connected to the upper punch 5. The upper punch 5 is thus raised in the clockwise rotation RL of the spindle 7 by means of the nut 8 in the direction y. Thus, the upper punch 5 is lowered in the anti-clockwise direction LL of the spindle 7 by means of the nut 8 in the direction y '.The nut 8 is connected to the upper punch 5 by a connecting piece VS. The connecting piece VS can be moved upwards y and downwards y' on the press frame 4 together with the nut 8, and the nut 8 is supported on the press frame 4 in a rotationally fixed manner via the connecting piece VS.

[0048] The spindle 7, which is shown in side view and in section in Figures 4 and 5, comprises a five-start external thread AG7, and the nut 8, which is shown in section in Figure 3, comprises a five-start internal thread IG8. As already mentioned above, the external thread AG7 and the internal thread IG8 are adapted to one another in such a way that the nut 8 moves upwards or downwards when the spindle 7 rotates, depending on the direction of rotation.

[0049] Three threads 9a, 9b, 9c of the spindle 7 (see Figure 4) are designated as examples. All five threads 9a, 9b, 9c are machined in such a way that their flank bottoms 10a, 10b, 10c, viewed in a longitudinal section of the spindle 7, each have a continuously concave curvature 11a, 11b, 11c. This is shown by way of example in the enlarged sectional view of the spindle drive 2 shown in Figure 6 using the concave curvature 11a of the flank bottom 10a of the thread 9a of the spindle 7.

[0050] Three threads 12a, 12b, 12c of the nut 8 (see Figure 3) are also designated as examples. All threads 12a, 12b, 12c of the nut 8 are machined such that their flank bases 13a, 13b, 13c each have a continuously concave curvature 14a, 14b, 14c. This is shown as an example in the enlarged sectional view of the spindle drive 2 shown in Figure 6 using the concave curvature 14a of the flank base 13a of the thread 12a of the nut 8.

[0051] Based on the flank base 10a of the first thread 9a of the spindle 7, it is clear from Figure 6 how this runs in the longitudinal section from a lower flank 9a-1 to a center 9a-2 of the flank base 10a along a curve K9a, wherein the curve K9a has a constant radius R9a.

[0052] Based on the flank base 13a of the first thread 12a of the nut 8, it is evident from Figure 6 as an example how this runs in the longitudinal section from an upper flank 12a-3 to ■ a lower flank 12a-1 on a curve K12a, wherein a radius R12a of the curve K12a is gradually reduced. .

[0053] From the longitudinal section of Figure 6 it is also evident how a maximum radial distance RA between a tooth flank ZF7 of the spindle 7 and the flank bottom 13a of the nut 8 is approximately 75% of the maximum radial distance RI between a tooth flank ZF8 of the nut 8 and the flank bottom 10a of the spindle 7.

[0054] From the longitudinal section of Figure 6 it is further evident that the maximum radial distance RA between the tooth flank ZF7 of the spindle 7 and the flank bottom 13a of the nut 8 is approximately 16% of a tooth depth ZT8 of the nut 8.

[0055] The rotation axis D7 and the axis A8 are not shown in exact position in Figure 6, but only schematically.

[0056] The method according to the invention is described below in particular with reference to Figures 7a and 7b, which are printed side by side on figure sheet 7 to facilitate an overview. Figure 7a shows the spindle drive 2, also shown in Figures 2 and 6, of the press 1 according to the invention in an enlarged detail in section. Figure 7b shows a section corresponding to the illustration in Figure 1 through the spindle drive ST of the prior art press P. The spindle drive 2 and the spindle drive ST are shown to the same scale.

[0057] The method according to the invention for optimizing the spindle drive ST of the press P according to the prior art, which comprises the spindle S and the nut M, comprises the steps:

[0058] - machining of all threads GGS of the spindle S in such a way that a maximum radial tooth depth ZTS of the spindle S measured in the longitudinal section shown in Figure 7b is increased and

[0059] - machining of all threads GGM of the nut M in such a way that a maximum radial tooth depth ZTM of the nut M measured in the longitudinal section is increased.

[0060] Figure 7a shows the spindle drive 2 created by machining the spindle drive ST. In this illustration, in addition to the tooth depth ZT7 of the spindle 7 achieved by machining, the original tooth depth is also shown for explanation purposes.

[0061] ZTS is shown. Furthermore, in Figure 7a, in addition to the tooth depth ZT8 of the nut 8 achieved by machining, the tooth depth ZTM 1 existing before machining is also shown.

[0062] Reference symbol 1 is:

[0063] DS rotation axis of S (state of the art)

[0064] GGS thread pitch of S (state of the art)

[0065] GGM thread of M (state of the art)

[0066] M nut (state of the art)

[0067] P Press (state of the art)

[0068] S spindle (state of the art)

[0069] ST spindle drive (state of the art)

[0070] ZTM tooth depth of M (state of the art)

[0071] ZTS tooth depth of S (state of the art) y upwards y ' downwards

[0072] 1 ' Press

[0073] 2 spindle drive

[0074] 3 Drive unit

[0075] 4 press frame

[0076] 5 upper stamps

[0077] 6 understamps

[0078] 7 spindle

[0079] 8 mothers

[0080] 9a-9c thread of 7

[0081] 9a -1 lower flank of 9 a

[0082] 9a-2 middle of 10a of 9a

[0083] 10a-10c flank floor of 9a-9c

[0084] 11a- 11c concave curvature of 10 a- 10c

[0085] 12a- 12c thread pitch of 8

[0086] 12a-l lower flank of 12a

[0087] 12a-3 upper flank of 12a

[0088] 13a-13c flank floor of 12a-12c 14a-14c concave curvature of 13a- 13c

[0089] A8 axis of 8

[0090] AG7 five-start external thread of 7

[0091] D7 rotation axis of 7 g

[0092] IG8 five-start internal thread of 8

[0093] K9a curve at 9a-l

[0094] Class 2 a curve at 12a

[0095] LL left-hand rotation of 7

[0096] R9a radius at 9a-l

[0097] RI 12 radius at 12 a

[0098] RA maximum radial distance between ZF7 and 13a

[0099] RI maximum radial distance between ZF8 and 10a

[0100] RL Right run of 7

[0101] VS connecting piece between 8 and 5

[0102] ZF7 tooth flank of 7

[0103] ZF8 tooth flank of 8

[0104] ZT 7 tooth depth of 7 . '

[0105] ZT 8 tooth depth of 8

Claims

Claims:

1. Press (1) comprising a spindle drive (2), a drive unit (3), a press frame (4), an upper punch (5) and a lower punch (6), - wherein the spindle drive (2) comprises a spindle (7) and a nut (8), - wherein the spindle (7) is rotatable by the drive unit (3) in a left-hand rotation (LL) or in a right-hand rotation (RR) and is fixed in the axial direction (y, y'), - wherein the nut (8) is movable upwards and downwards in the axial direction (y, y') on the press frame (4) and is not rotatable, - wherein the spindle (7) comprises a multi-start external thread (AG7), - wherein the nut (8) comprises a multi-start internal thread (IG8) ■, - wherein the external thread (AG7) and the internal thread (IG8) are adapted to each other in such a way that the nut (8) moves upwards (y) or downwards (y') when the spindle (7) rotates, depending on a direction of rotation, characterized in that - that all threads (9a-9c) of the spindle (7) are machined in such a way that their flank bottoms (10a-10c) when viewed in a longitudinal section of the spindle (7) each have a continuous concave curvature (11a-11c) and - that all threads (12a-12c) of the nut (8) are machined such that their flank bottoms (13a-13c) when viewed in a longitudinal section of the nut (8) each have a continuous concave curvature (14a-14c).

2. Press according to claim 1, characterized in that each flank bottom (lOa-lOcj of the spindle (7) in the longitudinal section of starting from a lower flank (9a-l) and extending to the middle of the flank floor (10a-10c) along a curve (K9a), the curve (K9a) having a constant radius (R9a).

3. Press according to claim 1, characterized in that each flank bottom (13a-13c) of the nut (8) runs in the longitudinal section from an upper flank (12a-3) to a lower flank (12a-l) on a curve (K12a), wherein the radius (R12a) of the curve (K12a) decreases stepwise or continuously.

4. Press according to at least one of the preceding claims, characterized in that, viewed in longitudinal section, the maximum radial distance (RA) between a tooth flank (ZF7) of the spindle (7) and the flank base (13a) of the nut (8) is at least 50% and, in particular, at least 70% of the maximum radial distance (RI) between a tooth flank (ZFM) of the nut (8) and the flank base (10a) of the spindle (7).

5. Press according to claim 4, characterized in that the maximum radial distance (RA) between the tooth flank (ZF7) of the spindle (7) and the flank base (13a) of the nut (8) is at least 10% and, in particular, at least 15% of a tooth depth (ZT8) of the nut (8).

6. A method for optimizing a spindle drive (ST) of a press, comprising a spindle (S) and a nut (M), includes the following steps: - abrasive machining of all threads (GGS) of the spindle (S) such that a maximum radial tooth depth (ZTS) of the spindle (S) measured in a longitudinal section is increased and - abrasive machining of all threads of the (GGM) nut (M) such that a maximum radial tooth depth (ZTM) of the nut (M) measured in the longitudinal section is increased.

7. The method of claim 6, characterized in that the maximum radial tooth depth (ZTM) of the nut (M) is increased by at least 10% and in particular by at least 15%.

8. The method of claim 6, characterized in that the maximum radial tooth depth (ZTS) of the spindle (S) is increased by at least 2% and in particular by at least 5%.

9. Method according to at least one of claims 6 to 8, characterized in that the flank surfaces (lOa-lOc) of the spindle (7) each have a continuous concave curvature (lla-llc) when viewed in longitudinal section after machining.

10. Method according to at least one of claims 6 to 9, characterized in that the flank ends (13a-13c) of the nut (8) after machining each have a continuous concave curvature (14a-14c) when viewed in the longitudinal section:.

11. Method according to at least one of claims 6 to 10, characterized in that the machining is carried out such that, viewed in the longitudinal section, a maximum radial distance (RA) between a tooth flank (ZF7) of the spindle (7) and the flank base (13a) of the nut (8) is increased by at least 50% and in particular by at least 70% of a maximum radial distance (RI) between a tooth flank (ZF8) of the nut (8) and the flank base (10a) of the spindle (7).

12. Method according to claim 11, characterized in that the machining is carried out such that the maximum radial distance. (RA) between the tooth flank (ZF7) of the spindle (7) and the The flank floor (13a) of the nut (8) is at least 10% and in particular at least 20% of a tooth depth (ZT8) of the nut (8).

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