JP2003025149A - Method and device for finishing tooth flank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the tooth flank finishing accuracy by suppressing the fluctuation in the machining load even when there is a variance in the dimensions of a gear in the pre-finishing operation. SOLUTION: After the plunging of grinding a tooth flank of a gear 1 is performed by rotating an annular grinding wheel 7 having an internal gear 7a engaged with the gear 1 in an engaged condition with the gear 1, the grinding wheel 7 is moved in the axial direction of the gear 1, and the oscillation of grinding the tooth flank of the gear 1 is performed while each tooth flank of the gear 1 and the grinding wheel 7 is moved in a slidable contact manner while pressed against each other. The mean value of the machining load in the ending stage of the plunging is calculated, and if the mean value of the machining load is high, the cutting quantity of bringing the grinding wheel 7 close to the gear 1 in the engaging direction is corrected, and if the mean value of the machining load is low, correction is made so as to increase the cutting quantity, followed by the subsequent oscillation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tooth surface finish for plunging a tooth surface of a work having a tooth profile using a grindstone having a tooth profile that meshes with the tooth profile, and then performing an oscillation process for finishing. A processing method and apparatus.

[0002]

2. Description of the Related Art In plunge machining, a gear and a grindstone having a tooth profile that meshes with the gear are pressed in a predetermined amount while being pressed in a direction in which the tooth tips of the gear and the grindstone approach and mesh with each other. The meshing operation of the gear and the grindstone is performed. By this plunge machining, the tooth flanks of the gear are ground by a predetermined amount, and subsequently, the tooth flanks of the gear and the grindstone are slidably moved in the tooth width direction while being pressed against each other for oscillation machining. The waviness is removed and the finishing process is completed.

[0003]

By the way, in the pre-processing of the above-mentioned finishing, if the dimension of the gear varies due to the over-ball diameter method, etc. The load (machining load) of the motor for performing plunge machining differs for each gear that has variations.

FIG. 7 shows the machining load from the start to the end of plunge machining and the completion of finishing machining when the over-ball diameter (OBD) is within the standard in the pre-machining (solid line). A large case (broken line) and a case smaller than the standard (dashed line) are shown respectively. It can be seen that when the overball diameter is large, the machining load is larger than when it is small, and the machining load varies depending on the difference in the overball diameter.

When the diameter of the overball is large, the gear and the grindstone are strongly pressed against each other at the machining start position, so that the grinding ability of the grindstone is exceeded at the end of the plunge machining (because the peripheral speed is extremely low), and the specified allowance is taken. However, if the machine is shifted to the oscillation processing in this state, the tooth surface accuracy varies due to the deflection of the work support tool and the increase in the level of the natural frequency of each part, resulting in a decrease in the finishing processing accuracy.

On the other hand, when the overball diameter is small, the machining load at the end of the plunge machining is not so different from that within the standard, but the machining load is also reduced during the subsequent oscillation machining. The original correction ability of the oscillation process for flattening the undulation of the tooth surface is insufficient, and the tooth surface accuracy varies and the finishing processing accuracy decreases.

Further, due to the load on the tooth surface of the grindstone caused by the fluctuation of the processing load, the accuracy of the tooth surface of the grindstone deteriorates and the abrasive particles of the grindstone are worn out at an early stage, and it is necessary to frequently perform the dressing (clogging removal) work of the grindstone. Occurs, resulting in deterioration of workability and shortening of the life of the grindstone.

Therefore, an object of the present invention is to correct the machining load variation and improve the accuracy of tooth surface finishing even if the dimensions of the gears are varied during the pre-finishing.

[0009]

In order to achieve the above object, the invention of claim 1 provides a workpiece having a tooth profile and a grindstone having a tooth profile meshing with the tooth profile, and The tips are pressed toward each other in a direction in which they mesh with each other, and in a state where they are cut by a predetermined amount, after performing plunge processing for grinding the tooth surface of the work by causing the work and the grindstone to mesh with each other, Each tooth surface of the work and the grindstone, in the tooth surface finishing method for performing the oscillation processing for finishing grinding the tooth surface of the work by sliding contact movement in the tooth width direction while pressing each other, in the plunge end plate When the machining load generated between the work and the grindstone is large, the mutual cutting amount of the work and the grindstone is small, and when the machining load is small, the cutting amount is large. So that, there is a processing method for correcting respectively.

According to a second aspect of the present invention, in the tooth surface finishing method according to the first aspect of the present invention, the magnitude of the machining load generated between the work and the grindstone is the load of the motor for performing plunge machining. There is as something.

According to a third aspect of the present invention, in the tooth surface finishing method according to the first aspect of the present invention, the magnitude of the machining load generated between the work and the grindstone is a load due to movement in meshing operation with each other. Is the detection value of the load sensor for detecting.

According to a fourth aspect of the invention, in the tooth surface finishing method of the first aspect, the magnitude of the machining load generated between the work and the grindstone is an average value within a predetermined time. There is.

According to a fifth aspect of the present invention, a work having a tooth profile and a grindstone having a tooth profile meshing with the tooth profile are pressed against each other in a direction in which the tooth tips of the work and the grindstone approach each other and mesh with each other. A cutting drive means for performing a constant amount of cutting, a plunge driving means for plunging the tooth surface of the work by performing a meshing operation in a state where the work and the grindstone are meshed with each other by the cutting operation, the work and the grindstone Each of the tooth surfaces of the above, the oscillation processing drive means for slidingly moving in the tooth width direction while pressing each other and performing the oscillation processing, and the magnitude of the processing load generated between the work and the grindstone at the end of the plunge processing. Load detecting means for detecting the depth, and when the processing load detected by this processing load detecting means is large, the phase between the work and the grindstone Small in depth of cut, when the processing load is small so that the depth of cut is large, there is a configuration in which a control means for controlling, respectively.

[0014]

According to the invention of claim 1 or 5, when the machining load generated between the work and the grindstone at the end of the plunge machining is large, the amount of cutting between the work and the grindstone is small, Since the depth of cut is increased when the load is small, the corrections have been made so that even if there are variations in the dimensions of the workpiece during pre-finishing,
Fluctuations in processing load during finishing are suppressed, and finishing accuracy can be improved. Further, since the load on the tooth surface of the grindstone due to the fluctuation of the machining load is reduced, the dressing work of the grindstone is reduced, the workability is improved, and the life of the grindstone can be prevented from being shortened.

According to the second aspect of the present invention, the machining load is detected as the load of the motor for performing the plunge machining.

According to the invention of claim 3, the processing load is used as the detection value of the load sensor for detecting the load due to the movement of the work and the grindstone in the meshing operation with each other, so that the load detection accuracy is improved. be able to.

According to the fourth aspect of the present invention, the magnitude of the machining load generated between the work and the grindstone is set to an average value within a predetermined time, so that the fluctuation of the machining load in the finishing process can be further suppressed. It can be surely suppressed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the overall construction of a tooth surface finishing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view showing its essential portions, and FIG. 3 is its control block diagram. . The work W has a gear 1 at the left end in FIGS. 1 and 2, and both ends thereof are fixedly held by a head side center pin 3 and a tail side center pin 5. The center pins 3 and 5 are rotatably held by left and right holding mechanism portions 9 and 11 provided on the bed 7.

On the other hand, the grindstone 7 for grinding the tooth surface of the gear 1 described above is formed in an annular shape, and the inner peripheral surface thereof is provided with internal teeth 7a having a tooth profile that meshes with the tooth profile of the gear 1. This grindstone 7 is rotatably held on the inner peripheral surface of a grindstone base 9 formed in an annular shape, and is formed in an annular shape by a plunge-processing servomotor 13 as a plunge-driving means provided on an end side surface of the grindstone base 9. Rotate around the center.

Although not shown in FIGS. 1 and 2, the grindstone unit 15 composed of the grindstone 7, the grindstone base 9, the plunge machining servomotor 13 and the like is used for cutting as a cutting drive means. By the servo motor 17, it is possible to move with respect to the bed 7 in the arrow Z direction corresponding to the vertical direction in FIG. By this movement in the Z direction,
As shown in FIG. 4, the gear 1 and the inner teeth 7a of the grindstone 7 move toward and away from each other in a direction in which they mesh with each other.

When the gear 1 and the internal teeth 7a of the grindstone 7 are in mesh with each other, the plunge-working servomotor 13 is driven to rotate the grindstone 7, whereby the gear 1 is rotated and the tooth surface of the gear 1 is rotated. Is grinded by the grindstone 7 by a predetermined amount (plunge processing).

Although not shown in FIGS. 1 and 2, the grinding wheel base unit 15 described above has an oscillation processing servomotor 1 as an oscillation processing driving means.
9, it is possible to reciprocate with respect to the bed 7 in the arrow X direction corresponding to the left-right direction in FIG.

After the plunge machining is completed, the servomotor 19 for oscillation machining is driven to reciprocate the grindstone unit 15 in the X direction, whereby the gear 1 and the grindstone 7 relatively move in the width direction and the gear 1 moves. Finishing process (oscillation process) is performed on the tooth surface. At this time, the grindstone 7 is the grindstone base 9
Positioning is fixed by a locate pin 37 provided at the position of which rotation is restricted.

The plunge-processing servomotor 1 described above
3, the cutting servo motor 17 and the oscillation processing servo motor 19 are, as shown in FIG. 3, servo amplifiers 27 and 29, respectively, in the internal sequencer 25 of the NC device 23 as a control means that incorporates the NC program 21.
And 31 and are driven and controlled by the NC device 23.

Further, in the tail side center pin 5 supporting the work W, as shown in FIG. 2, there is provided a load sensor 33 as a load detecting means for detecting a machining load during the plunge machining performed by rotating the grindstone 7. It is built in. The detection value of the load sensor 33 is input to the internal sequencer 25 of the NC device 23 via the receiver 35 as shown in FIG. The internal sequencer 25 receives the load detection value and controls the driving of the cutting servo motor 17 via the servo amplifier 29 in order to correct the cutting amount.

Next, the operation will be described with reference to FIGS. FIG. 5 is a flow chart showing the operation of the above-mentioned finishing machine, and FIG. 5 is a machining operation diagram showing the machining operation by the tooth surface finishing machine with the lower part as the cutting direction and the left and right directions as the oscillation direction.

First, the grindstone unit 15 is moved closer to the gear 1 in the Z direction by the cutting servomotor 17.
As shown in FIG. 4, the internal teeth 7a of the grindstone 7 are meshed with the gear 1 (point P in FIG. 6). This point P is a state in which no backlash has occurred between the grindstone 7 and the gear 1. In this state, plunge machining is performed while performing a cutting operation (an operation of bringing the grindstone 7 closer to the gear 1 in the Z direction) during the section α up to the point Q (step 101). In plunge machining, the plunge servomotor 13 is driven to rotate the grindstone 7. By this rotation, the gear 1 meshing with the internal teeth 7a of the grindstone 7 is rotated, the gear 1 and the grindstone 7 are meshed with each other, and the tooth surface of the gear 1 is ground by a predetermined amount by the grindstone 7.

In this plunge machining, the depth of cut is 0.1 to 0.2 mm and the feed rate in the cutting direction is 0.4 to 1.
It is 0 mm / min.

On the other hand, during the plunge machining, the machining load is detected by the load sensor 33 (step 10).
3). The detected value of this machining load is taken in by the internal sequencer 25 in the section β from the R point at the end of the plunge machining to the Q point near the end of the plunge machining, and the average value in the section β is calculated (step 105). .

Then, a correction value for the depth of cut is calculated based on the average value of the machining loads (step 107). That is, in step 107, an approximate expression (cutting amount correction value = cutting amount correction value = μm) representing the relationship between the machining load average value and the cutting amount correction value (μm).
A × processing load + B: A and B are constants depending on the workpiece W), and a cutting amount correction value is calculated. Based on this correction value, the cutting servo motor 17 is drive-controlled to determine the cutting amount A correction operation is performed (step 109).

In step 107, the processing load average value is L₁
If it is smaller, the dimensions of the gear 1 in the pre-processing are smaller than the standard.
If it is small, in this case, enter the depth correction value.
Direction to increase the cutting depth and increase the machining load.
It On the other hand, the processing load average value is L _TwoWhen larger, add
This is the case when the size of the gear 1 is larger than the standard.
In this case, subtract the depth of cut correction value in the relief direction to determine the depth of cut.
To reduce the processing load. This makes the processing load
When the gear dimensions for pre-processing are within the standard
Is almost equal to. Average processing load is L₁L is above₂Less than
In the case of, the depth of cut is not changed.

After the depth of cut is corrected as described above, a prescribed amount of grinding is performed by plunge processing, and oscillation processing is further performed (step 111), whereby the finishing processing for the tooth surface of the gear 1 is completed (step 111). 113). In the oscillation processing, the oscillation processing servomotor 19 is driven to reciprocate the grindstone 7 in the Z direction. At this time, the rotation of the grindstone 7 is restricted by the locate pin 37. By this reciprocating movement, the tooth surface of the gear 1 and the tooth surface of the internal tooth 7a of the grindstone 7 are pressed against each other, and slidingly move in the tooth width direction to finish the tooth surface of the gear 1.

In plunge machining after the correction of the depth of cut, the machining load is almost uniform, so even if the dimensions of the gear 1 are varied during the pre-machining before the finishing machining, the prescribed amount of cutting can be reliably performed. It Further, in the oscillating process following the plunge process, even if the dimensions of the gear 1 are varied in the pre-process before the finishing process, the machining load becomes substantially uniform. Therefore, the finishing process accuracy by the oscillating process should be improved. You can

Further, since the fluctuation of the machining load is eliminated, the grindstone 7
Since the burden on the tooth surface is reduced, dressing work of the grindstone 7 is reduced, workability is improved, and the life of the grindstone 7 can be prevented from being shortened.

In the above-mentioned oscillation processing,
In the section γ shown in FIG. 6, the cutting amount is 0.01 to 0.002.
mm, feed rate in oscillation direction is 200 to 400
mm / min.

Although the detection value of the load sensor 33 provided on the tail side center pin 5 is used as the processing load in the above embodiment, the plunge processing servomotor 13 is used.
It is also possible to detect the load applied to and use this as the processing load.

The load sensor 33 provided on the tail-side center pin 5 has a higher detection accuracy than in the case of detecting the motor load, and therefore is suitable for gears in which the tooth surface accuracy is difficult to obtain and the meshing ratio is low. On the other hand, when the motor load is used as the processing load, the cost is lower than that when the load sensor 33 is used, and the detection accuracy is lower than that of the load sensor 33. Therefore, the accuracy is relatively high and the gear ratio is high. Suitable for

Further, in the above embodiment, the average value is used as the processing load when correcting the depth of cut, but the integrated value of the detected values within the section γ may be used.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a tooth surface finishing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing a main part of the tooth surface finishing apparatus of FIG.

3 is a control block diagram of the tooth surface finishing apparatus of FIG. 1. FIG.

FIG. 4 is an explanatory view showing a meshing state of a gear and a grindstone in the tooth surface finishing device of FIG. 1.

5 is a flowchart showing an operation of the tooth surface finishing apparatus of FIG.

FIG. 6 is a machining operation diagram showing a machining operation by the tooth surface finishing machine of FIG. 1;

FIG. 7 is an explanatory diagram showing a comparison of machining loads from the start to the end of plunge machining and the completion of finish machining depending on the size of the gear.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Gear 7 Whetstone 13 Plunge processing servo motor (plunge processing drive means) 17 Cutting servo motor (cutting drive means) 19 Oscillation processing servo motor (oscillation processing drive means) 23 NC device (control means) 33 Load sensor (load detection means)

Claims (5)

[Claims] 1. A workpiece having a tooth profile and a grindstone having a tooth profile that meshes with the tooth profile are pressed in a direction in which the tooth tips of the workpiece and the grindstone approach each other and mesh with each other, and a predetermined amount is cut. In the state, after the plunge process of grinding the tooth surface of the work by causing the workpiece and the grindstone to engage with each other, the tooth surfaces of the work and the grindstone are slidably moved in the tooth width direction while pressing each other. In the tooth surface finishing method for performing the oscillation processing for finishing grinding the tooth surface of the work, when the processing load generated between the work and the grinding wheel at the end of the plunge processing is large, the work and the grinding wheel The tooth surface finishing method is characterized in that the respective cutting amounts are corrected so that the cutting amount becomes large when the cutting load is small and the cutting load is small. 2. The tooth surface finishing method according to claim 1, wherein the magnitude of the machining load generated between the workpiece and the grindstone is a load of a motor for performing plunge machining. 3. The magnitude of the machining load generated between the work and the grindstone is a detection value of a load sensor that detects a load due to movement in a meshing operation with each other. The described tooth surface finishing method. 4. The tooth surface finishing according to claim 1, wherein the magnitude of the machining load generated between the work and the grindstone is an average value within a predetermined time. Processing method. 5. A cutting tool for pressing a work having a tooth profile and a grindstone having a tooth profile that meshes with the tooth profile in a direction in which the tooth tips of the work and the grindstone approach each other and mesh with each other to cut a predetermined amount. The driving means and the plunge driving means for plunging the tooth surface of the work by engaging the work and the grindstone in a state where the work and the grindstone are engaged with each other by the cutting operation, and the tooth surfaces of the work and the grindstone. , A process for detecting the magnitude of a machining load generated between the work and the grindstone at the plunge end of the plunge machining, and the oscillation machining drive means for oscillating by slidingly moving in the tooth width direction while pressing each other. When the processing load detected by the load detection means and the processing load detection means is large, the mutual cutting amount between the work and the grindstone is small. A tooth surface finishing apparatus, comprising: a control unit that controls the cutting amount to increase when the processing load is small.