METHOD FOR PRODUCING A ROTOR OF A SCREW COMPRESSOR OR A WORKPIECE WITH A HELICAL PROFILE

Abstract

A method for producing a rotor of a screw compressor or a workpiece with a helical profile, the rotor or the workpiece with a helical profile having a number of profiles in the form of groove-shaped recesses running in a spiral manner on the outer periphery thereof, the groove-shaped recesses being fine-machined using a grinding tool for the purpose of generating a precise profile. To be able to produce rotors and workpieces having variable pitch along the axial extent of the rotor or the workpiece as precisely as possible, the groove-shaped recesses are fine-machined with a grinding tool which only touches the surface of the groove-shaped recess at one point during the grinding process. The entire surface to be machined is machined by the grinding tool through line-by-line traversing of the surface to be machined.

Claims

1-12. (canceled)

13. A method for producing a rotor of a screw compressor or a workpiece with a helical profile, wherein the rotor or the workpiece with a helical profile has a number of profiles in the form of groove-shaped recesses running in a spiral manner on its outer circumference, wherein the groove-shaped recesses are fine-machined using a grinding tool for the purpose of generating a precise profile, wherein the groove-shaped recesses are fine-machined with a grinding tool which only touches the surface of the groove-shaped recess at one point during the grinding process, wherein the entire surface to be machined is machined by the grinding tool through line-by-line traversing of the surface to be machined, wherein the groove-shaped recesses of the rotor or of the workpiece with a helical profile have a variable pitch or a variable profile over the axial course of the rotor or of the workpiece with a helical profile, wherein a grinding tool in the form of a grinding wheel is used, wherein the abrasive section of the grinding wheel has a gothic profile in radial section.

14. The method according to claim 13, wherein the line-by-line traversing is performed by carrying out a number of grinding strokes in which the grinding tool is moved in radial direction relative to the rotor or to the workpiece having a helical profile.

15. The method according to claim 13, wherein the line-by-line traversing is performed by carrying out a number of grinding strokes in which the grinding tool is moved in axial direction relative to the rotor or to the workpiece having a helical profile.

16. The method according to claim 13, wherein the line-by-line traversing is performed by carrying out a number of grinding strokes in which the grinding tool is moved in combination in radial direction and in axial direction relative to the rotor or to the workpiece with a helical profile.

17. The method according to claim 13, wherein as grinding wheel a steel base body tool is used which is coated with an abrasive material bonded to the steel base body by means of galvanic coating.

18. The method according to claim 13, wherein during grinding of the groove-shaped recesses the axis of rotation of the rotor or of the workpiece with a helical profile and the radial infeed movement of the grinding wheel are changed relative to another in an interpolating manner.

19. The method according to claim 13, wherein during grinding of the groove-shaped recesses the axis of rotation of the rotor or of the workpiece with a helical profile and the feed axis in the direction of the axis of rotation of the rotor or of the workpiece with a helical profile relative are changed relative to another in an interpolating manner.

20. The method according to claim 18, wherein during grinding of the groove-shaped recesses furthermore the swivel axis of the grinding tool and/or the feed axis of the grinding wheel in axial direction of the grinding wheel are interpolatingly changed.

Description

[0019] An example of an embodiment of the invention is shown in the drawings.

[0020] FIG. 1 shows a perspective view of two intermeshing rotors of a screw compressor, the pitch of the helical profiling of the rotors being constant over their axial extent,

[0021] FIG. 2 shows a perspective view of two intermeshing rotors of a screw compressor, the pitch of the helical profiling of the rotors being variable over their axial extent,

[0022] FIG. 3 shows schematically in a face section of the rotor the engagement conditions of a grinding wheel in the groove-shaped profile of the helical profiling of a rotor during the grinding process,

[0023] FIG. 4 shows a perspective view of the engagement conditions of the grinding wheel in the groove-shaped profile of the helical profiling of a male rotor during the grinding process,

[0024] FIG. 5 shows a perspective view of the engagement conditions of the grinding wheel in the groove-shaped profile of the helical profiling of a female rotor during the grinding process,

[0025] FIG. 6 shows schematically the course of movement of a grinding wheel over the surface of the groove-shaped recess according to a first embodiment of the invention, and

[0026] FIG. 7 shows schematically the course of the movement of the grinding wheel over the surface of the groove-shaped recess according to a second embodiment of the invention.

[0027] FIG. 1 shows a pair of intermeshing rotors of a screw compressor, a first rotor 1 (male) being in engagement with a second rotor 2 (female). Both rotors 1, 2 have helical and groove-shaped recesses 3 and 4, respectively, on their outer circumferences, which correspond to each other. Thus, when the pair of rotors rotates, a conveying effect is produced in a known manner. The respective axis of rotation of the rotors is designated by a.

[0028] Whereas in the rotors according to FIG. 1 the pitch of the groove-shaped recess is constant over the axial extension of the rotor, it is clear from FIG. 2 that this is not the case here. The pitch of the groove-shaped recesses is smaller at the right-hand end of the rotors than at the left-hand end; the pitch thus increases gradually from right to left.

[0029] The grinding process according to the invention is particularly recommended for such rotors with variable pitch.

[0030] This is illustrated in FIG. 3: Here it can be seen in a frontal section (the axis of rotation a of the rotor 1, 2 is perpendicular to the drawing plane) that a grinding tool 5 in the form of a grinding wheel is used to grind the surface 7 of the groove-shaped recesses 3, 4 in points or lines. The grinding wheel 5 has a gothic profile 6 which, in radial section, consists of two arcs which are joined at the tip.

[0031] The grinding wheel 5 can be moved relative to the rotor 1, 2 in radial feed direction r, while the rotor 1, 2 is simultaneously rotated about its axis of rotation a in an interpolating manner, i.e. the position of the abrasive surface of the grinding wheel 5 resulting from the nominal geometry is precisely controlled between the movement of the two axes a and r. Furthermore, it is possible that the grinding wheel 5 is moved simultaneously in the direction of the feed axis t, which points in the axial direction b of the grinding wheel 5. Finally, it is also possible for the grinding wheel 5 to be moved about the swivel axis B, which in FIG. 3 is perpendicular to the drawing plane and therefore perpendicular to the axis b.

[0032] During the grinding process, there is also a relative movement between the workpiece (rotor) and the tool (grinding wheel) in the direction of the feed axis v.

[0033] This means that up to five machine axes can be moved simultaneously to grind the surface 7 with the grinding wheel 5.

[0034] It is essential that there is always only point contact between the surface 7 and the abrasive surface of the grinding wheel 5, as indicated in FIG. 3. Point contact means that the contact area between the workpiece and the tool has only a small surface area (in contrast to this, when grinding with a profile grinding wheel, there is linear contact).

[0035] FIG. 4 shows this situation again in perspective. The groove-shaped recesses 3 of the rotor 1 (male) are machined by the grinding wheel 5. FIG. 5 shows the same situation for rotor 2 (female).

[0036] FIG. 6 shows the machining of the surface 7 of the groove-shaped recess 3, 4 in the radial stroke (in profile height direction). It is indicated how the individual machining strokes are performed by moving the grinding wheel 5 in the radial direction r, with the rotor 1, 2 correspondingly rotating about its axis of rotation a at the same time, in order to machine the surface 7 with the abrasive surface of the grinding wheel. After execution of such a machining stroke, the grinding wheel is moved further in axial direction a at the reversal points of the meandering path sketched in FIG. 6.

[0037] FIG. 7 shows the machining of the surface 7 in the axial stroke (in the direction of the profile width). It can be seen here how the grinding wheel is moved in the axial direction a of the rotor, whereby of course, according to the geometry of the profiling to be produced, the rotor 1, 2 is rotated about its axis of rotation a correspondingly. After execution of such machining stroke, at the reversal points of the meandering path sketched in FIG. 7, the grinding wheel is further moved in radial direction r. With regard to the axial stroke, it should be noted that the groove-shaped recess 3, 4 can also be ground to full depth.

[0038] It should be mentioned that a combination of the solutions according to FIGS. 6 and 7 can also be useful. In this case, there is then a combined radial and axial stroke, so that the feed direction is at an angle to the axis of rotation of the rotor.

[0039] Furthermore, it should be noted that FIGS. 6 and 7 show only the machining of the flanks of the groove-shaped recess due to their schematic representation. Of course, the process can also be used to grind the head and/or foot area of the profile of the rotor or the workpiece with a helical profile.

LIST OF REFERENCES

[0040] 1 Rotor of a screw compressor (male) [0041] 2 Rotor of a screw compressor (female) [0042] 3 Groove-shaped recess [0043] 4 Groove-shaped recess [0044] 5 Grinding tool (grinding wheel) [0045] 6 Gothic profile [0046] 7 Surface of the groove-shaped recess [0047] P Contact point between grinding tool and surface of the profile to be machined [0048] r Radial infeed direction [0049] a Axial direction of the rotor (axis of rotation of the rotor) [0050] b Axial direction of the grinding wheel [0051] v Axis of infeed in the direction of the axis of rotation of the rotor [0052] B Swivel axis of the grinding wheel [0053] t Axis of infeed of the grinding wheel in axial direction of the grinding wheel