Method for the roller-straightening of crankshafts

Abstract

The invention concerns a process for roll straightening crankshafts (8, 8) using crankshaft deep rolling tools (1 to 7), in particular work rollers (18,19) which, while the crankshaft (8, 8) is rotated about its axis of rotation (21), are pressed into the recesses (14 to 17) or radii that delimit the bearing pins (Hi, Pi) on either side with a roll straightening force (27, 30) that constantly fluctuates around the circumference of a bearing pin (H.sub.1 to H.sub.5, P.sub.1 to P.sub.4). Roll straightening is carried out by determining the individual vector (34) of the runout by size and direction (35) at each main bearing (Hi) of the crankshaft (8, 8). The largest (45) or resulting vector (25) is determined from the individual vectors (34), then the main bearing pins (Hi) and crankpins (Pi) of the crankshaft (8, 8) are roll straightened with a roll straightening force (27, 30, 49, 50) the size (25) and direction (26) of the largest (45) or resulting vector (25) of which is between 0 and a multiple of the largest (45) or resulting vector (25).

Claims

1. A method for roll straightening a crankshaft during or after a deep rolling process using deep rolling tools, wherein a work roller is pressed into a recess on a side of a bearing journal of the crankshaft with a straightening force, the method comprising: determining an individual vector (44, 45, 46, 47) of a runout for each bearing journal (Hi, Pi) of the crankshaft (8, 8); determining a largest vector (45) from the individual vectors (44, 45, 46, 47) according to a size value and a direction (48); and then applying a straightening force (46, 50) to each bearing journal (Hi, Pi) of the crankshaft (8, 8); wherein a direction of the straightening force (46, 50) lies in the direction (48) of the largest vector (45); wherein a size value of the straightening force (46, 50) continually changes as the crankshaft is rotated through 360 degrees around an axis of rotation; and wherein the size value of the straightening force (46, 50) varies between 0 and a multiple value of the size value of the largest vector (45).

2. The method according to claim 1, wherein the size value of the straightening force (27, 30 and 49, 50) is changed from one bearing journal (Hi, Pi) to another bearing journal (Hi, Pi) of the crankshaft.

3. The method according to claim 1, wherein the roll straightening is performed during the deep rolling process.

4. The method according to claim 1, wherein the crankshaft (8, 8) is divided up into a plurality of individual length sections along an axial length of the crankshaft; and wherein each the individual length section is roll straightened separately.

5. A method for roll straightening a crankshaft during or after a deep rolling process using deep rolling tools, wherein a work roller is pressed into a recess on a side of a bearing journal of the crankshaft with a straightening force, the method comprising: determining an individual vector (44, 45, 46, 47) of a runout for each bearing journal (Hi, Pi) of the crankshaft (8, 8); determining a resulting vector (25) from the individual vectors (34, 35, 36, 37, 38) according to a size value and a direction (26); and then applying a straightening force (46, 50) to each bearing journal (Hi, Pi) of the crankshaft (8, 8); wherein a direction of the straightening force (46, 50) lies in the direction (26) of the resulting vector (25); wherein a size value of the straightening force (27, 30) continually changes as the crankshaft is rotated through 360 degrees around an axis of rotation; and wherein the size value of the straightening force (27, 30) varies between 0 and a multiple value of the size value of the resulting vector (25).

6. The method according to claim 5, where the size of the straightening force (27, 30 and 49, 50) is changed from one bearing journal (Hi, Pi) to another bearing journal (Hi, Pi) of the crankshaft.

7. The method according to claim 5, wherein the roll straightening is performed during the deep rolling process.

8. The method in accordance with claim 5, wherein the resulting vector (25) is determined by vectorial addition of the individual vectors (34, 35, 36, 37, 38).

9. The method according to claim 5, wherein the crankshaft (8, 8) is divided up into a plurality of individual length sections along an axial length of the crankshaft; and wherein each the individual length section is roll straightened separately.

10. A method for roll straightening a crankshaft, the crankshaft comprising a plurality of bearings along a length of the crankshaft and a longitudinal axis, the method employing deep rolling tools comprising a support roller head including support rollers, a deep rolling head and work rollers, the method comprising: rotating the crankshaft about the longitudinal axis; measuring the size and direction of a runout on each of the plurality of bearings to determine a corresponding runout vector for each of the plurality of bearings; determining a size and direction of a resultant runout vector from a sum of each of the runout vectors for each of the plurality of bearings; for each of the plurality of bearings, applying at a first point located on a circumference of the bearing, a roll straightening force being directed toward the first longitudinal axis, the roll straightening force having a first size at least equal to the size of the resultant runout vector and having a direction matching the direction of the resultant runout vector; and for each of the plurality of bearings, continuously reducing the size of the roll straightening force applied to the bearing as the crankshaft rotates about the longitudinal axis such that, at a second point located on the circumference of the bearing that is 180 degrees from the first point, the roll straightening force applied to the bearing has a second size equal to one of zero and a fraction of the size of the resultant runout vector.

11. The method according to claim 10, further comprising, for each of the plurality of bearings, continuously increasing the size of the roll straightening force applied to the bearing from the second size to the first size as the crankshaft continues to rotate about the longitudinal axis from the second to the first point.

12. The method according to claim 11 wherein the first size is greater than the size of the resultant runout vector; and wherein the second size is equal to zero.

13. The method according to claim 11 wherein the first size is equal to the size of the resultant runout vector; and wherein the second size is equal to zero.

Description

DRAWINGS

(1) The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

(2) The invention is described in detail below using a design example. The following figures each show a scaled down section of the equipment.

(3) FIG. 1: shows a longitudinal section through a deep rolling machine for crankshafts.

(4) FIG. 2: shows a measuring device for determining the runouts, front view.

(5) FIG. 3: shows the same measuring device as in FIG. 2, side view.

(6) FIG. 4: shows a section through any main bearing pin (rear) of a crankshaft, showing the resulting runout and the roll straightening force.

(7) FIG. 5: shows a section through any main bearing pin (rear) of a crankshaft, showing the maximum runout and the roll straightening force.

(8) Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

(9) Example embodiments will now be described more fully with reference to the accompanying drawings.

(10) In order to measure the bend in a crankshaft 8, 8, its runout is measured. For the runout measurement, the largest deflection (m) and the direction () of the largest deflection are measured at the main bearings H1-H5. As an example, if the result were 268/177, the runout would be 268 m at an angle of 177. The angle measurement refers to the coordinates system 9 or the crankshaft 8, 8, and is defined the same way for all crankshaft types. The direction of the highest-quality pin bearing P4, counted from pin 10, is 0. The direction of rotation 20 of the crankshaft 8, 8 during deep rolling, facing the chuck 11 of the deep rolling machine 12, is anti-clockwise. The angle count direction is clockwise in relation to the workpiece crankshaft 8, 8.

(11) In FIG. 1, for example, a 3-cylinder crankshaft 8 is clamped in a deep rolling machine 12 between the chuck 11 and the centre sleeve 13. At main bearing pins H1. H2. H3 and H4, recesses 14 and 15 are deep rolled using crankshaft deep rolling tools 1, 3, 5 and 7. At crankpins P1, P2 and P3, recesses 16 and 17 are deep rolled using crankshaft deep rolling tools 2, 4 and 6. Each crankshaft deep rolling tool 1 to 7 comprises a support roller head 1, 2, 3 with support rollers 33 (FIG. 3) and a deep rolling head 4, 5, 6 and 7. Work rollers 18 and 19 penetrate recesses 14 and 15 during deep rolling of the main bearings H1 to H4, and recesses 16 and 17 during deep rolling of the pin bearings P1 to P3. During deep rolling, the crankshaft 8 is rotated around its main axis of rotation 21 in the direction of the arrow 20 by the chuck 11.

(12) In FIG. 3, the position of the work rollers 18 and 19, and of support rollers 33, during deep rolling and roll straightening corresponds to that during in-process deep rolling and roll straightening.

(13) The runout can be measured using a measuring device 22 for example, which can be swiveled around a swivel axis 23. The measuring device 22 has several measuring sensors 24 arranged in a line, which can be lowered onto the main bearing pins H1 to H5, of a 4-cylinder crankshaft 8, for example, by swiveling the measuring device 22 about the swivel axis 23. Turning the crankshaft 8 in direction 20 determines the individual runouts 34 to 38 on the main bearings H1 to H5 by size and direction, angle 39 to 42.

(14) The addition of the vectors that takes place in the machine control unit (not shown) is used to determine the resulting runout 25 by size and direction 26 from the individual runouts 34 to 38.

(15) The resulting runout 25 then triggers a roll straightening force 27 on the crankshaft deep rolling tools 1 to 7, the size of which matches the resulting vector 25 and its direction 26. The roll straightening forces 27 and 30 are always directed towards the centre 31 of the bearing pin in question H1 to H5 or P1 to P4. At the position 29 of the bearing pins Hi and Pi opposite the point 28 at which the largest roll straightening force 27 is applied, the roll straightening force 30 is equal to 0, for example. Around the circumference of the bearing pins Hi to Pi, the roll straightening forces 30 drop continuously, as can be seen from the outline 32. In contrast to the example in FIG. 4, where the roll straightening force at position 29 assumes the value 0, it can also assume a finite value at the same point, which is a fraction of the maximum roll straightening force 27.

(16) A simpler process than that described in the example above is also a perfectly feasible way of achieving the goal. Such a process is illustrated in FIG. 5. Here, either during or after deep rolling, the individual runouts 44, 45, 46 and 47 are measured at the individual main bearing pins H1, H2, H3 and H4. The largest of these by size and direction 48 is runout 45. With a roll straightening force 49 to match this individual runout 45, the crankshaft 8,8 is now roll straightened at the main bearing pin H2, for example, or at a crankpin P1 or P2 adjacent to the main bearing pin H2. This roll straightening force 49 also assumes values between a multiple of the maximum runout 45 and 0. The force curve around the circumference is shown by line 50.

(17) As described above, the maximum runout 45 is calculated by the machine control unit. The preferred type of procedure (according to either FIG. 4 or FIG. 5) is determined in advance by means of a test. However, a complex machine control unit can also calculate and apply the preferred procedure in-process.

(18) The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.