Abstract
A system and method for grinding the exterior of a shaft part with rotationally symmetrical sections and bases which have centering bores and which define a reference longitudinal axis and rotational axis of the shaft part. The shaft part is held between tips which engage into the centering bores during the grinding process using a grinding disk, and the shaft part is additionally supported on the rotationally symmetrical sections by means of a support device. The current diameter values of the rotationally symmetrical sections are measured and transmitted to a controller, by means of which the support device is updated with respect to the measured diameter values while continuously supporting the rotationally symmetrical sections until target dimensions are achieved.
Claims
1. A method for grinding the exterior of a shaft part with rotationally symmetrical sections and end surfaces into which centering bores have been introduced, which bores define a reference longitudinal axis and rotational axis of the shaft part, wherein during grinding, up to the end of finishing grinding by means of a grinding disk, the shaft part is held between tips that engage into the centering bores, and supported on the rotationally symmetrical sections by means of a support device with a first and a second support unit, wherein the shaft part is disposed between the grinding disk and a first support unit of the support device, and a measurement device is an in-process measurement device and measures diameter values of the rotationally symmetrical sections of the shaft part, transmits these measurement values to a controller, and this controller, on the basis of these measurement values, actively updates setting of the grinding disk with respect to the measured diameter values, and updates the support device, continuously supporting the rotationally symmetrical sections, all the way to the finished dimension of the shaft part, wherein the support device, as the first support unit, has a support disk or a contact ruler, and the second support unit has a contact ruler being configured as a support rail having separate support regions and is set against the shaft part by two drives, each CNC-controlled.
2. The method according to claim 1, wherein the shaft part is rotationally driven.
3. The method according to claim 1, wherein the support disk and the shaft part essentially run without slip relative to one another.
4. The method according to claim 1, wherein the grinding disk, the shaft part, and the support disk are regulated with regard to their respective speed of rotation.
5. The method according to claim 1, wherein the shaft part is driven/braked during finishing grinding, by means of the grinding disk and the support disk.
6. The method according to claim 1, wherein the support disk is configured with a coating in the manner of a grinding disk.
7. The method according to claim 1, wherein measuring of the diameter values takes place by means of at least two measurement devices.
8. The method according to claim 1, wherein the support device has two contact rulers, which are adjusted relative to one another and are configured in the form of a prism.
9. The method according to claim 1, wherein the grinding disk and the shaft part are moved axially relative to one another, and in this regard, the shaft part is ground on the rotationally symmetrical section, on a planar side, at least partially parallel in terms of time.
10. The method according to claim 1, wherein the support disk is configured as a regulation disk, and the rotationally driven shaft part run essentially without slip relative to one another, wherein the grinding disk, the shaft part, and the regulation disk are regulated in terms of their speed of rotation.
11. The method according to claim 10, wherein the shaft part is driven during finishing grinding by means of the grinding disk and the regulation disk, wherein the grinding disk and the regulation disk form a grinding gap in which the shaft part is disposed, supported on the support rail.
12. The method according to claim 1, wherein two support rails are adjusted relative to one another and form a prism as the support device that is updated with respect to the respective current ground diameter.
13. A system composed of a grinding machine and a shaft part, for grinding the exterior of the shaft part, with rotationally symmetrical sections and end surfaces with centering bores introduced into them, which bores define a reference longitudinal axis and rotational axis of the shaft part, with a grinding disk that is disposed on a grinding spindle and is rotationally driven by way of a CNC axle, with a workpiece headstock having a first tip, and a tailstock having a second tip, wherein the shaft part is driven so as to rotate, by means of the first and second tip, during grinding, about a reference longitudinal axis defined in this way, and permanently held, wherein a support device having a first and a second support unit, which are adjustable relative to one another, and a measurement device are provided, by means of which measurement signals of the current diameter of the rotationally symmetrical section of the shaft part can be passed on to a controller, and on the basis of which the first and the second support unit can constantly be updated with respect to the current diameter of the rotationally symmetrical section, all the way to the finished dimension, in such a manner that the shaft part is doubly supported by means of the support units that lie opposite the grinding disk, and by means of the tips that are constantly in engagement, wherein the first support unit is a support disk or a contact ruler, and the second support unit is a contact ruler being configured as a support rail having separate support regions and is set against the shaft part by two drives, each CNC-controlled.
14. The system according to claim 13, wherein the grinding disk, the support disk, and the shaft part can each be regulated in terms of their speed of rotation, with CNC control.
15. The system according to claim 13, wherein the support disk sits on a spindle and is divided, and that each part can be updated with respect to the current diameter of corresponding rotationally symmetrical sections of the shaft part, supporting these sections.
16. The system according to claim 13, wherein the first support unit is a contact ruler, and the second support unit is a further contact ruler, which can be moved relative to the contact ruler, forming a prism-like support region on the rotationally symmetrical section of the shaft part.
17. The system according to claim 13, wherein the measurement device is an in-process measurement device.
18. The system according to claim 13, wherein drivers are present on the workpiece headstock, by means of which drivers the shaft part can be rotationally driven, and which can be released from engagement on the shaft part.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further advantages and details of the present invention will now be explained using exemplary embodiments and making reference to the following drawings. The figures show:
(2) FIG. 1: a fundamental side view of the system consisting of grinding machine and shaft part;
(3) FIG. 2: a top view of the grinding machine with shaft part according to the invention, in a viewing direction X according to FIG. 1;
(4) FIG. 3: a view of the grinding machine with shaft part according to the invention, along the section plane A-A according to FIG. 2;
(5) FIG. 4: a view as in FIG. 3, but with retracted drivers;
(6) FIG. 5: a grinding machine according to the invention, with a shaft part that is modified as compared with FIG. 2, and a grinding disk correspondingly adapted to it, in the same view as FIG. 2;
(7) FIG. 6: a side view as in FIG. 1, with a support device that consists of two contact rulers;
(8) FIG. 7: a view along the section plane B-B according to FIG. 6.
DETAILED DESCRIPTION
(9) In FIG. 1, the system according to the invention, composed of the grinding machine and the shaft part or workpiece 10, is shown in a side view. A grinding disk 1 that can be positioned in the X1 direction is in engagement with the shaft part 10. A support disk 2, which can be positioned against the shaft part 10 along an X2 setting axis, and is in engagement with it, is provided lying opposite the grinding disk 1. The support disk 2 represents a first support unit. The shaft part 10 in turn is supported on a second support unit in the form of a support ruler 3. The support ruler 3 can also be set against the respective current ground diameter of the shaft part 10 by way of a CNC axle. This means that the support ruler can constantly be updated with respect to the current ground diameter.
(10) It is true that this fundamental structure according to FIG. 1 looks similar to an arrangement for centerless grinding at first glance. However, according to the present invention, no centerless grinding is carried out on the grinding machine that belongs to the system according to the invention, because the shaft part 10 is held between tipsnot shown in FIG. 1during the entire grinding process shown in FIG. 1.
(11) The grinding disk is mounted on a grinding spindle 4 (not shown), which is rotationally driven by a drive motor, also not shown. The grinding spindle drive is equipped with a speed of rotation regulator that is controlled by a CNC controller of the grinding machine of the system according to the invention, which is also not shown in FIG. 1 for the sake of simplicity. The setting axles X1 for the grinding disk 1 and X2 for the first support unit, configured as the support disk 2, are configured as CNC axles, in each instance. The support disk 2 is set onto a support spindle 5 (not shown), which in turn is driven by a drive motor that is also not shown, with regulation of the speed of rotation, wherein the support spindle 5 is mounted on a support headstock (not shown), which can be moved along the CNC-controlled X2 axis that is shown.
(12) FIG. 2 represents the fundamental arrangement of the system according to the invention, which comprises the grinding machine and the shaft part, in a viewing direction X according to FIG. 1. From FIG. 2, it is evident that the shaft part 10 is clamped in place between a tip 11 of a workpiece headstock 13 and a tip 14 of a tailstock 15. Rotational drive of the shaft part 10 takes place by means of a driver 12. During the entire grinding process, the workpiece 10 remains clamped between the tips 11, 14. The tip 11 and the driver 12 of the workpiece headstock 13 are rotationally driven by a CNC-controlled motor, with regulation of the speed of rotation. After the shaft part 10 has been clamped in place between the tips 11, 14, the driver 12 ensures that the shaft part 10 will be driven rotationally, by means of form-fitting engagement with it. At the same time, the grinding disk 1 of the grinding headstock and the support disks 2, 2 and the support ruler 3 (not shown) are positioned by way of corresponding CNC-controlled axles. Two support disks 2, 2 are disposed on the support spindle and set against the shaft part 10 in its center region, so that this part is supported at two locations between the tips 11 and 14. The support disks 2, 2 partially take on a support function in the center region of the shaft part 10, so to speak. As compared with centerless grinding or the arrangement that implements centerless grinding, in which the regulation disk that is present there is disposed over the complete workpiece length, since the regulation disk also takes on a driving or braking function for the workpiece during grinding in the case of centerless grinding, in the case of the solution according to the invention, drive of the shaft part 10 is implemented by way of the drivers disposed on the workpiece spindle 13. The support function of the support disks 2, 2 shown in FIG. 2 ensures reliable grinding of the rotationally symmetrical sections, with permanent clamping between the tips 11, 14, specifically without bezels having to be provided. In this regard, the support disks 2, 2 are particularly configured as low-wear disks made of hardened steel or of hard metal. Great quality demands are made on the support disk, above all with regard to having a particularly low concentricity error. Otherwise, the concentricity error could lead to a poorer grinding result, specifically in spite of the permanent clamping of the workpiece or shaft part 10 between the tips 11, 14. Holding the shaft part 10 between the tips 11, 14 offers sufficient rigidity so that the shaft part 10 does not have to be specially supported in the region of the tips 11, 14.
(13) In order to be able to automatically set or implement targeted conicity on the workpiece or shaft part by means of the grinding disk and/or the support disk during grinding, the grinding spindle 4 with the grinding disk 1 and the support spindle 5 with the support disks 2, 2 are mounted on a pivot axle, in each instance, so that the spindles can be pivoted in the horizontal plane. The respective pivoting movements or pivot axles are identified as B1 and B2, respectively.
(14) By means of this method of procedure, it is possible for a precise cylinder shape or a targeted conicity to be ground on the workpiece. This embodiment with the two pivot axles is a preferred, non-compulsory embodiment (not shown).
(15) FIG. 3 shows a view along the section plane A-A according to FIG. 2. The second support unit, not shown in FIG. 2, is shown in the form of a support ruler 16 in FIG. 3. This support ruler or contact ruler 16, configured as a support rail, has separate support regions 17, 17 and is set against the shaft part 10 by means of two drives, each CNC-controlled, at the current diameter that has just been ground. During its clamping between the tips 11, 14, the shaft part 10 partially lies on the contact ruler 16, on its support regions 17, 17. The grinding headstock, not shown, the support headstock, also not shown, the workpiece headstock 13, the tailstock 15, and the support ruler or support rail 16 with the drives 18, 19 are all mounted on a common machine bed 20. In this way, the required rigidity is guaranteed, so that when the method according to the invention or the system according to the invention, consisting of grinding machine and shaft part, are used, the greatest possible precision for the shaft part can be achieved. In order to be able to set the support disks 2, 2 and the support ruler 16 precisely against the shaft part 10, in accordance with the respective current diameter, an in-process measurement head 21 is disposed on at least one of the two ends of the shaft part 10. In the embodiment according to FIG. 3, in-process measurement heads 21, 22 are disposed on both shaft ends. With these measurement heads 21, 22, the respective current diameter of the shaft part can be continuously detected during grinding. The measured diameter values recorded with them are transmitted to a machine controller, not shown. On the basis of these measurement values, the machine controller controls the support disks 2, 2 and the support ruler 16 continuously, in accordance with the current measurement values at the shaft part 10, specifically during the complete grinding process, until the finished dimension, i.e. the final dimension is achieved.
(16) By means of the method according to the invention or by means of the system according to the invention, it is possible to grind both smooth shafts and what are called recessed, i.e. stepped shafts. The number of support disks that define the respective direct partial support locations, as well as the corresponding configuration of the support ruler can be flexibly established, depending on the workpiece shape, workpiece dimensions, and the like. The speeds of rotation of the support disks 2, 2 and of the workpiece headstock 13 must be continuously monitored and adjusted, if necessary, since the current diameter of the shaft part 10 changes continuously during grinding, and no slip is supposed to occur between the shaft part 10 and the support disks 2, 2. Since the diameters of grinding disk and support disks 2, 2 are generally different, the corresponding circumference speeds of the support disks and the grinding disk must be continuously adjusted with respect to the mantle surface of the shaft part 10.
(17) In FIG. 4, a view as according to FIG. 3 is shown, but with the difference that the drivers 12 for rotational drive of the shaft part 10 are retracted in the finishing grinding shown in FIG. 4. In this regard, according to the invention, the tips 11, 14 and the two support disks 2, 2, as well as the support ruler 16 are permanently set against the shaft part 10, i.e. they touch the shaft part 10 and support it. In this case, drive takes place not by way of the workpiece headstock 13, but rather by means of the grinding disk 1 (not shown) and the support disks 2, 2, wherein the shaft part 10 nevertheless remains completely clamped between the tips 11, 14 even during this phase. In this case, as well, the two measurement heads 21, 22 lie against the shaft part, so that the current shaft part diameter can be continuously measured during the process, and on the basis of these measurement values for the respective current diameters, the support disks 2, 2 and the support ruler 16 can be continuously set to the precise reference position.
(18) Only for loading and unloading shaft parts or workpieces 10 into or from the system according to the invention are the tips 11, 14 retracted, specifically along the displacement axles 23 and 24, so that a finished ground shaft part 10 can be removed from the grinding machine.
(19) In the exemplary embodiment according to FIG. 5, the fundamental arrangement of which corresponds to that according to FIG. 2, once again the shaft part 10 is clamped between the tips 11, 14 during the entire grinding process, wherein the drivers 12 on the workpiece headstock 13 ensure that the shaft part 10 is rotationally driven during the grinding process. Once again, two support disks 2, 2 are disposed on the support spindle 5, which disks support the shaft part 10 in its center region, on the side opposite the grinding disk engagement. In the case of the shaft part according to FIG. 2, only one continuous rotationally symmetrical section is provided over the entire length of the shaft part. In contrast, the shaft part 10 according to the exemplary embodiment according to FIG. 5 has a collar in its center region. This collar additionally has planar surfaces 25, which are also ground with the grinding disk. Because of the placement of a collar in the center region of the shaft part 10, the grinding disk is divided up into two partial grinding disks 30, 30. The distance between the partial grinding disks, which are both disposed on the grinding spindle 4, is slightly greater than the width of the collar of the shaft part 10, which has the planar surfaces 25. The partial grinding disk 30 has a grinding coating 31, whereas the partial grinding disk 30 has a grinding coating 32.
(20) In the present exemplary embodiment, the partial grinding disk 30 additionally has a grinding coating on its end face, which faces the partial grinding disk 30. The end face grinding coating 33 provided there serves to grind the collar disposed on the shaft part 10, in its center region, with regard to its planar surface 25. In addition, it can be provided that the partial grinding disk 30 also has such an end face grinding coating, which is then disposed on the end face of the partial grinding disk 30 that faces the partial grinding disk 30. So that the planar surface 25 on the collar of the shaft part 10 can be ground, it is provided that the grinding disk 30, 31 and the workpiece 10 or the shaft part 10 perform a relative movement in relation to one another in the longitudinal direction of the shaft part 10. In the present exemplary embodiment according to FIG. 5, the workpiece headstock 13 with its tip 11 and the tailstock 15 with its tip 14 are automatically displaceable under CNC control. In this way, the result is achieved that the shaft part 10 is set against the grinding coating 33 of the partial grinding disk with its planar side 25, and thereby the planar side 25 can be ground. In this regard, grinding of the planar side takes place parallel in terms of time, at least in part. However, it is also possible that not only the rotationally symmetrical circumference sections and the planar side 25 are ground completely parallel in terms of time. In contrast, if the workpiece headstock 13 or the tailstock 15 is not adjustable in the axial direction, the grinding spindle 4 with its partial grinding disks 30, 30 can also be axially displaced, according to an embodiment that is not shown. In the exemplary embodiment according to FIG. 5, the axial displacement of the workpiece headstock is brought about by a CNC-controlled Z2 axle, and that of the tailstock 15 by means of a Z1 axle, which is also under CNC control. Preferably, CBN is used as a coating.
(21) In FIG. 6, a further exemplary embodiment is shown in a fundamental diagram that corresponds to that according to FIG. 1. In this exemplary embodiment, the shaft part 10 is once again ground by means of the grinding disk 1. In place of the first support unit in the form of a support disk, a support ruler 35 is provided, so that the support of the shaft part 10 during grinding is reliably supported during grinding, with permanent clamping between tips, by means of two support rulers, the support ruler 3 (second support unit) and the support ruler 35 (first support unit). Both the support ruler 3 and the support ruler 35 can not only be set against the shaft part 10 by way of respective CNC-controlled setting axles 36, 37, but also can be actively updated with respect to the currently measured active. Both support rulers 3, 35 are structured to be wear-resistant at their support surface, and this is particularly implemented by means of a PCD (polycrystalline diamond) coating. Setting or updating of the support rulers 3, 35 with respect to the respective current diameter of the shaft part 10 take place as a function of one another, so that reliable support of the workpiece 10 can be implemented during the entire grinding process, with permanent clamping between tips. The two support rulers 3, 35 form a prism that approximates a V shape, based on their setting or updating with respect to the current diameter of the shaft part 10, which take place as a function of one another. The drivers 12, not shown, must also engage on the workpiece in order to achieve the finished dimension in this exemplary embodiment, so that rotational drive of the shaft part 10 is guaranteed during the entire grinding process.
(22) FIG. 7, finally, represents a representation that is analogous to FIGS. 3 and 4, which shows a view along the section plane B-B according to FIG. 6. In this FIG. 7, it is shown that the two support rulers 3, 35 each form a partial support for the shaft part 10. The fundamental function, in which the tips 11, 14 clamp the workpiece in place during the entire grinding process, is implemented in this exemplary embodiment, as well.
