Method for grinding or polishing a gear or workpiece having a gear-like profile in a grinding or polishing machine

Abstract

The invention relates to a method for grinding or polishing a gear wheel (1, 2) in a grinding or polishing machine (3), wherein the machine (3) has two workpiece spindles (4, 5) for receiving workpieces (1, 2) and at least one grinding or polishing spindle (6) with a grinding or polishing tool (7). The invention provides a method for optimal operation without increasing the machining time and without the need for external measuring systems. The method comprises the following steps: a) grinding or polishing a first workpiece (1) received on a workpiece spindle (4); b) receiving a second workpiece (2) on another workpiece spindle (5) in a manner temporarily parallel to the grinding or polishing of the first workpiece (1), and measuring the gear teeth (8) of the workpiece (2) to determine the position of the tooth gap (9), wherein the measuring of the gear teeth (8) comprises scanning a gear tooth or profile side (10) of at least one tooth gap (9) using a tactile measuring element or a non-contact measuring device (11) to determine the effective oversize of the gear tooth side (10); c) after completing the grinding or polishing of the first workpiece (1): grinding or polishing the second workpiece (2) received on another workpiece spindle (5) based on the determined position of the tooth gap (9) and / or the measured effective oversize of the gear tooth side (10).

Description

Technical Field

[0001] The invention relates to a method for grinding or polishing a gear or a workpiece having a gear-like profile in a grinding or polishing machine, wherein the grinding or polishing machine comprises at least two workpiece spindles for receiving the workpieces and at least one grinding or polishing spindle having a grinding or polishing tool. Background Art

[0002] Grinding machines with more than one workpiece spindle are known in the state of the art. They have the advantage that non-productive times during machining can be reduced significantly. The machining of the workpiece on one workpiece spindle and the loading and unloading of the workpiece on the other workpiece spindle are then temporarily carried out in parallel. After loading, the workpiece is aligned and centered on the second workpiece, i.e. the position of the tooth gap or contour gap of a prefabricated workpiece, for example in the form of a gear, is determined so that the grinding tool can enter the gap in a targeted manner during the actual grinding operation.

[0003] The cycle time of this process determines how long it may take to load, unload and align the workpiece.

[0004] Therefore, non-contact inductive sensors are often used to detect the position of the gap in the tooth or profile, which quickly scan the circumference of the gear tooth or profile in order to determine the position of the gap into which the grinding tool must enter. Therefore, this sensor can detect the gap center of the gear or similar profile with a detectable switching signal, and thus conclude the deformation due to hardening and the position of the workpiece on the workpiece spindle.

[0005] However, with this solution it is not possible to determine the actual stock machining allowance of the flanks of the tooth or the profile. DE 198 57 592 A1 discloses a method for grinding a gear, wherein the grinding machine is equipped with two workpiece spindles, each for holding a workpiece, and with a grinding spindle for the tool. Sensors are provided for aligning the gear on the workpiece spindles; they do not detect the effective oversize of the tooth flank. EP 2 284 484 A1 describes a method for quickly measuring the oversize of a gear, but does not provide any reference to a machining concept with two workpiece spindles. Summary of the invention

[0006] While reference is made to grinding processes in the present invention and hereinafter, it should also be understood that alternative polishing processes may be used in the same manner to which the present invention is applicable.

[0007] The invention is based on the object of further developing a process of the above-mentioned type so that it is possible to obtain improved information about the workpiece to be ground or polished in a time-neutral manner without the use of external measuring systems, thereby optimizing the grinding or polishing process. This method of improving the grinding or polishing result should be achieved without increasing the process time and without the use of external measuring systems.

[0008] This object scheme comprises the following steps according to the method provided by the present invention:

[0009] a) grinding or polishing a first workpiece received on the workpiece spindle;

[0010] b) in a manner temporarily parallel to the grinding or polishing of the first workpiece: receiving a second workpiece on another workpiece spindle and measuring a tooth or gear-like profile of the workpiece in order to determine the position of a tooth gap or profile gap, wherein measuring the tooth or gear-like profile comprises scanning a tooth or profile flank of at least one tooth gap or profile gap using a tactile measuring element or a non-contact measuring device in order to determine an effective oversize of the tooth or profile flank;

[0011] c) After finishing the grinding or polishing of the first workpiece: grinding or polishing a second workpiece received on another workpiece spindle using the determined position of the tooth gap or profile gap and / or the measured effective oversize of the tooth or profile flank as a basis.

[0012] When performing the above step b), a plurality of tooth gaps or contour gaps may also be scanned; specifically, all tooth gaps or contour gaps may be scanned.

[0013] Preferably, the measurement according to step b) above is firstly carried out using a measuring probe. Alternatively, it is however also possible that the measurement is carried out using a laser.

[0014] In a preferred embodiment of the method, the grinding or polishing according to step c) above is carried out by specifying grinding or polishing parameters including the actual oversize of the tooth or profile flank. Thus, the affected parameters may be the feed rate between the grinding or polishing tool and the workpiece and / or the number of grinding or polishing strokes and / or the infeed of the grinding or polishing tool into the workpiece.

[0015] After grinding according to step c) above, the ground or polished tooth or gear-like profile of the workpiece can be measured again.

[0016] The tactile measuring element or the contactless measuring device can be arranged on the linear component, by which it can be moved and positioned in the translation direction.

[0017] Furthermore, inductive sensors can also be arranged in the grinding or polishing machine, by means of which the position of the tooth gap or contour gap is determined.

[0018] The proposed concept thus enables efficient determination of the actual existing allowance and deformation due to hardening before machining.

[0019] Therefore, temporarily parallel to the machining of the workpiece on the first workpiece spindle, the workpiece to be machined on the second workpiece spindle is measured by means of a probe or a contactless measuring element, the tooth backlash or contour clearance is found and the existing allowance and deformation due to hardening are determined.

[0020] Usually, the two workpiece spindles are permanently arranged in the machine tool, whereby a partition wall can be provided between them if necessary in order to form two separate partial spaces and thus to keep the cooling lubricant away from the spindle that is not currently grinding. However, it is also possible to remove the workpiece spindles or at least the workpiece holders from the machine or to insert them again using a handling system, so that the measurement or the above-mentioned alignment can be carried out outside the machine.

[0021] The invention makes use of the fact that sometimes during a grinding or polishing operation sufficient time is left for the other workpiece spindle to be kept, so that the actual stock can be recorded.

[0022] Advantageously, the proposed process allows for better positioning of the workpiece relative to the grinding or polishing tool without the need for the use of double-sided rolling test benches that are otherwise commonly used in quality assurance.

[0023] Furthermore, it is possible to specify optimally adapted grinding or polishing parameters as a function of the predetermined effective oversize of the grinding or polishing and thus to optimize the grinding or polishing process for each individual workpiece to be processed.

[0024] If the cycle time is long enough, the finished ground or polished workpiece can be measured again before disassembly using a measuring probe or non-contact measuring element in order to detect any possible deviations between the ideal position of the tooth or contour on the workpiece base and the workpiece geometry caused by hardening deformation or actual allowance. By evaluating such systematic deviations, it is possible to work with correction settings if necessary and thus optimize the grinding or polishing process in a closed control loop.

[0025] The proposed process makes it possible to determine the effective allowance of the workpiece to be machined without much effort and without prolonging the machining time. Knowing this, the grinding or polishing process can then be optimized.

[0026] Generally speaking, the use of the proposed measuring probe or contactless measuring element instead of the inductive sensor used hitherto additionally provides the possibility of detecting the actual lateral allowance of at least one, preferably a number, particularly preferably all gaps.

[0027] However, it is also possible to use inductive sensors in addition in order to achieve further optimization of the process steps in combination with sensors and measuring probes or contactless measuring elements. In this case, only one gap can be measured by the tactile probe or contactless measuring element and thus the allowance can be detected, so that the workpiece can be aligned or centered with respect to this gap. The inductive sensor can then additionally measure all other teeth or gaps, so that improved statements about the complete workpiece can be made with the reference gap already measured by the tactile probe, the determined allowance and the further information of the inductive sensor.

[0028] Preferably, the tactile measuring element (especially the probe) or the contactless measuring element is positioned by means of a linear axis of the grinding machine. After calibrating the probe using a reference body of known geometry (eg a ball of known diameter), the probe can be moved to the desired position using the linear axis.

[0029] The measured values ​​of the probe or the contactless measuring element can be recorded by the machine control system and processed in a known manner in order to find the optimum center position of the workpiece relative to the grinding tool with reference to the gear teeth or the contour. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] An embodiment of the present invention is shown in the following figure.

[0031] Figure 1 A schematic diagram of a grinding machine comprising two workpiece spindles and a grinding spindle with a grinding tool is shown.

[0032] Figure 2 The measurement of the backlash using a measuring sensor is schematically shown.

[0033] Figure Number:

[0034] 1 Workpiece (gear)

[0035] 2 Workpiece (gear)

[0036] 3 Grinding machines / polishing machines

[0037] 4 Workpiece spindle

[0038] 5 Workpiece spindle

[0039] 6 Grinding spindle

[0040] 7 Grinding tools (grinding worm)

[0041] 8 Tooth / quasi-tooth profile

[0042] 9 Tooth clearance / profile clearance

[0043] 10 Tooth side / profile side

[0044] 11 Tactile measuring element (measuring sensor) /

[0045] Non-contact measuring device (laser)

[0046] 12 Straight running parts. DETAILED DESCRIPTION

[0047] Figure 1 Only very schematically is shown a grinding machine 3 equipped with two workpiece spindles 4, 5 and a grinding spindle 6. In the present embodiment, a workpiece 1 or 2 can be held (clamped) in each case on the two workpiece spindles 4, 5. A grinding tool 7 in the form of a grinding worm is arranged on the grinding spindle 6.

[0048] As from Figure 2 As can be seen from the overview of FIG. 1 , in this case, the workpieces 1 , 2 are gears with gear teeth 8. However, if another workpiece with a gear-like profile is machined instead of a gear, the following considerations also apply.

[0049] In principle, the actual grinding is carried out using the grinding worm 7 by grinding the workpiece 1 on one of the two workpiece spindles 4, while the preparatory actions for grinding are carried out on the other workpiece spindle 5. These involve first clamping the workpiece 2 on the workpiece spindle 5 and then aligning or centering it. The pre-machined workpiece 1, 2 with the gear teeth 8 (e.g. by hobbing) must be positioned relative to the grinding worm 7 so that the grinding surface of the grinding worm engages in the tooth gap 9 of the gear teeth 8 (see Figure 2 ).

[0050] The grinding process then removes the oversize from the respective tooth flank 10 by means of the grinding tool 7 .

[0051] For this purpose, during the grinding of a workpiece 1 on one workpiece spindle 4, a workpiece 2 on another workpiece spindle 5 is temporarily subjected to a parallel measuring process using a measuring element 11, such as Figure 2 As shown schematically in FIG.

[0052] In at least one tooth gap 9, two opposing tooth flanks 10 are measured by probing to determine the effective oversize of the tooth. To this end, a probe 11 is placed on a straight-running part 12 so that it can be moved to the desired measuring position. Figure 2 The arrows indicate the radial displacement of the measuring probe 11 relative to the tooth 8 , and the workpiece is rotated back and forth in a circle in order to measure the contour of the tooth flank 10 to be ground point by point.

[0053] It is therefore possible to determine an optimum center position of the workpiece 2 relative to the grinding worm 7 based on the measured oversize of at least one, preferably a plurality, particularly preferably all tooth gaps 9 , so that ideally the same amount of material is removed from both opposing tooth flanks 10 .

[0054] Such an optimization of the grinding process is only possible to a certain extent if, according to the state of the art, only inductive sensors are used to detect the position of the tooth space and the workpiece is centered based on this. In this case, there is no information about the actual oversize.

[0055] Measuring with a probe in the manner described requires more time than centering with an inductive sensor, but in many cases this time is not available until after the workpieces that have been temporarily parallel ground are completed.

[0056] Then, depending on the values ​​recorded for the effective oversize, it is possible in a further development of the proposed method to adjust the production parameters in order to optimize the grinding process. In particular, it is intended to change or adjust the feed speed between the grinding tool 7 and the workpiece 1, 2. Likewise, it is conceivable to adjust the number of grinding strokes or the size of the infeed of the grinding tool 7 to the workpiece 1, 2. Thus, the blank volume removed over time can be kept within a desired range, in particular constant.

[0057] While workpiece 2 is being ground, finished workpiece 1 is temporarily removed from the other tool spindle in parallel, the next workpiece is clamped and measured in the described manner. The workpieces are thus ground alternately on the two workpiece spindles. The above-described process of determining the excess is therefore carried out alternately on the two workpiece spindles, in each case parallel to the main machining time.

Claims

1. A method for grinding or polishing a gear or a workpiece having a gear-like profile in a grinding or polishing machine (3), wherein the grinding or polishing machine (3) comprises at least two first workpiece spindles (4) for receiving a first workpiece (1), a second workpiece spindle (5) for receiving a second workpiece (2) and at least one grinding or polishing spindle (6) having a grinding or polishing tool (7), Features: The method comprises the following steps: a) grinding or polishing the first workpiece (1) received on the first workpiece spindle (4); b) receiving the second workpiece (2) on the second workpiece spindle (5) in a manner temporarily parallel to the grinding or polishing of the first workpiece (1) and measuring a tooth or a gear-like profile (8) of the second workpiece (2) in order to determine the position of a tooth gap or a profile gap (9), wherein said measuring of the tooth or gear-like profile (8) comprises scanning a tooth or profile side (10) of at least one tooth gap or profile gap (9) using a tactile measuring element or a non-contact measuring device (11) in order to determine the effective oversize of the tooth or profile side (10); c) after completing the grinding or polishing of the first workpiece (1): grinding or polishing the second workpiece (2) received on the second workpiece spindle (5) based on the determined position of the tooth gap or profile gap (9) and the measured effective oversize of the tooth or profile side (10).

2. The method according to claim 1, characterized in that: When performing step b) as claimed in claim 1, a plurality of the tooth gaps or contour gaps (9) are scanned.

3. The method according to claim 1, characterized in that: When performing step b) as claimed in claim 1, all the tooth gaps or contour gaps (9) are scanned.

4. The method according to claim 1, characterized in that: The measuring of step b) according to claim 1 is performed using a measuring sensor.

5. The method according to claim 1, characterized in that: The measuring of step b) according to claim 1 is performed using a laser.

6. The method according to claim 1, characterized in that: The grinding or polishing of step c) according to claim 1 is performed by specifying grinding or polishing parameters including the actual oversize of the tooth or profile flank (10).

7. The method according to claim 6, characterized in that: The affected parameters may be the feed speed between the grinding or polishing tool (7) and the first workpiece (1) or the second workpiece (2) and / or the number of grinding or polishing strokes and / or the lateral feed of the grinding or polishing tool (7) to the first workpiece (1) or the second workpiece (2).

8. The method according to claim 1, characterized in that: After the grinding or polishing in step c) according to claim 1, the ground or polished tooth or gear-like profile of the workpiece is measured again.

9. The method according to claim 4, characterized in that: The tactile measuring element or the contactless measuring device (11) is arranged on a linear component (12) and can be moved and positioned in a translational direction by means of the linear component.

10. The method according to claim 1, characterized in that: An inductive sensor is also arranged in the grinding or polishing machine, by means of which the position of the tooth gap or profile gap (9) is determined.

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