JPH0344854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a finish rolling method for finishing rack teeth preformed by warm forging or cutting to desired dimensional accuracy.

In this type of method, a pinion tool 1 is meshed and pressed against a rack material 2 as shown in FIG. This is a method of rotating the pinion tool 1 while moving it relatively, but since the finishing accuracy is greatly affected by variations in the relative movement between the pinion tool 1 and the rough material 2, this method has traditionally been used to improve finishing accuracy. Relative movement between pinion tool 1 and easy rough material 2 and pinion tool 1
A forced drive system in which the rotation of the pinion tool 1 is forcibly performed, and a free drive system in which either the relative movement of the pinion tool 1 and the rough material 2 or the rotation of the pinion tool 1 are forcibly performed are known. According to the forced drive method, it is possible to reduce the relative movement between the pinion tool 1 and the rough material 2, especially the variation in the rotational speed of the pinion tool 1, and to bring the tooth profile closer to the ideal state, and according to the free drive method, Although the finishing accuracy is slightly degraded, the tooth profile can be brought close to a quasi-ideal state.

However, in conventional rolling methods using any of these methods, there is a difference in sliding speed before and after the meshing pitch line within the tooth surface, changes in contact load due to changes in the number of meshing points, presence or absence of contact between the pinion tooth tip and the rack tooth bottom, or Due to such fluctuations, finishing errors occur, and for example, compared to the desired tooth profile shown by the chain line in Figure 2, the shape of the rack tooth 3 becomes constricted at the root and swells at the tip, as shown by the solid line. There were cases where the shape became

That is, FIG. 3 is an explanatory diagram showing the case of finish rolling a rough rough material 2 having a rack tooth 3 with a predetermined helix angle, and the pinion tool 1 has a helix similar to the rack tooth 3 including the mounting angle. When the center axis of the pinion tool 1 is at the position indicated by the symbol in FIG. Yes, and the meshing ratio is 2 or more. When the pinion tool 1 moves by a minute distance ΔL from the position indicated by the symbol to the position indicated by the symbol, the mesh at the point P1 is released, the mesh at the point P4' is added, and at the same time the point P2 is At P2', point P3 changes to P3'. As the point of engagement changes in this way, the contact load changes. For example, at point P4', as shown in FIG. ' The rigidity varies depending on the dimension l from the tooth end. Therefore, the total force applied to the pinion tool 1 changes from the sum of the forces applied to points P1, P2, and P3 to the sum of the forces applied to points P2', P3', and P4',
In some cases, there may be meshing only at points P2 and P3, so the force applied to points P2 and P3 becomes the sum of the forces, and in the end, the contact load is generated while the pinion tool 1 rolls on the rough material 2. Changes from time to time.

Such variations in load during rolling cause finishing errors, so in order to improve finishing accuracy, it is necessary to suppress variations in load. here. To explain the occurrence of finishing errors due to load fluctuations,
Figure 5 shows that the meshing point of point P3 in Figure 3 is point P.
3' is a diagram showing local deformation of the meshing part when the cutting force F3 changes to F3';
The pinion center position O changes to a position obtained by adding the error generating displacement vector 12 to the displacement amount 11, and in this case, the reaction that was received on the ab⌒ plane changes to the cde⌒ plane. Therefore, the rate of change in the area of the surface receiving the load, ie, cde⌒/ab⌒, increases as the depth of cut t becomes smaller, and the larger the value, that is, the smaller the depth of cut t, the smaller the error-generating displacement vector 12 becomes. Note that R in FIG. 5 is the radius of curvature of a specific cross section of the pinion meshing portion. Therefore, in order to improve finishing accuracy, it is sufficient to reduce the depth of cut t per stroke of the pinion tool 1 that rolls on the rough rough material 2, but if the depth of cut t is reduced, However, there is a problem in that the finish rolling takes a long time and efficiency is reduced. Conventionally, in order to prioritize work efficiency, finish rolling is carried out by keeping the depth of cut t per stroke at a certain large constant amount, which limits the ability to improve finishing accuracy.

This invention was made in view of the above circumstances, and aims to provide a method that can perform finish rolling of rack teeth with high accuracy and speed. The point is that rotation is made smooth by the flywheel, and the amount of cutting per one stroke of the pinion tool, that is, the amount of cutting each time the pinion tool is reversely moved, is gradually reduced.

Examples of the present invention will be described below.

First, an apparatus for carrying out the method of the present invention will be explained. FIG. The back-up rack 11 is configured to roll on the rough material 12, and the rough material 12 is movable in the direction of the arrow 21 on a main body 19 having a slide groove 20, and the back-up plug 11 easily moves the pinion tool 10 onto the rough material. 12, and is attached to a fixed part 13 such as a machine frame via an adjustment means 14 such as a screw so that it can be moved back and forth toward the rough material 12. The pinion tool 10 is pressed against the rack material 12 by the rack 11, and the cutting depth t by the pinion tool 10 is adjusted by the adjusting means 14.
Further, a flywheel 15 is coaxially attached to the pinion tool 10 to smooth its rotation, so that the two rotate as one. Further, the central shaft of the pinion tool 10 is connected to a crank 17 via a connecting rod 16, and the crank 17 is rotated by a motor 18. A pinion tool 10 is adapted to reciprocate in the pitch line direction of the rough material 12.

Next, the method of the present invention using the above-mentioned device will be explained. Finish rolling of the rough rough material 12 is performed by cutting while reciprocating the pinion tool 10.
At the beginning of finish rolling, the depth of cut t is set to a large value, for example, about 0.03 mm, and the depth of cut t is gradually reduced, for example, exponentially, every stroke of the pinion tool 10, that is, every time the pinion tool 10 is reversely moved. The situation is shown in Figure 7. During finish rolling in this way, the equipment used is elastically deformed even slightly, and therefore the cutting depth is t, which is the point at which the entire finishing allowance is cut, that is, the depth of cut t.
If the pinion tool 10 is allowed to stand still once it has been reduced to zero, the elastic stress of the device will leave imprints of the pinion tool 10 on the rack teeth, or the cut will be greater than the intended finishing amount, so the depth of cut may be reduced. After the amount t becomes zero, as shown in FIG. 7, the pinion tool 10 is moved back and forth in a direction opposite to the cutting direction depending on the rigidity of the device.

While the pinion tool 10 is rolling as described above, the inertia rate (inertia moment) based on the shape and mass of the pinion tool 10
Since the inertia factor of the flywheel 15 and the motion system that rotates in synchronization with the flywheel 15 is added to the inertia factor, the overall inertia factor increases, and as a result, rotational fluctuations due to load fluctuations are suppressed, and the pinion tool 10 Rotation is smoothed out. In that case, near the cutting end point, that is, when the cutting amount t approaches zero, the rolling resistance force decreases and the inertia force of the flywheel 15 relative to the rolling resistance force increases; however, the flywheel 15 Since the inertia force of the flywheel 15 may act as a load for rolling, if the inertia force of the flywheel 15 is excessive compared to the rolling resistance force, there is a risk of causing finishing errors, and the crank 17 and This also increases the load on the connecting rod 16. Therefore, the inertia force exerted by the flywheel 15 increases as the rate of change in rotational speed or inertia rate increases. Therefore, the weight, diameter, etc. of the flywheel 15 are determined depending on the required finish accuracy of the easy teeth and the machine such as the crank 17. It is preferable that the rotational speed and rotational acceleration of the flywheel 15 be configured to be set appropriately depending on the system so that the rotational speed and rotational acceleration of the flywheel 15 change continuously.

However, in the method described above, the depth of cut t is reduced in the final process of finish rolling, and the pinion tool 10 is
Since the rotation of the tooth is stabilized by the flywheel 15, the finishing accuracy of the rack teeth can be improved.At the same time, since the depth of cut t is initially increased and then gradually decreased, the working time can be reduced without reducing the finishing accuracy. can be shortened.

In the above embodiment, the pinion tool 10 is moved in the direction of the pitch line of the rack teeth. This is an example in which the present invention is applied to a so-called free drive system in which the pinion tool 10 is rotated accordingly, but the present invention is not limited to the free drive system but can also be applied to a forced drive system. This invention also provides a pinion tool 10.
The present invention can also be applied to a device in which an idle gear is inserted between the back-up rack 11 and the back-up rack 11. If one idle gear is provided between the back-up rack 11 and the pinion tool 10 in FIG. 6, the relative movement between the rough material 12 and the main body 19 becomes zero, and the movement in the direction of the arrow 21 becomes unnecessary. , the detailed explanation will be omitted as the explanation is equivalent. When these forced drive systems and idle gears are used, the rigidity of the drive system and the rigidity of the entire device are different from those of the free drive system, but by appropriately setting the inertia force by the flywheel 15, The same effects as in the embodiment described above can be obtained.

As is clear from the above explanation, the finish rolling method of the present invention allows the rotation of the pinion tool to be smoothed by the flywheel, and
Since this method gradually reduces the amount of cut per stroke, that is, the amount of cut each time the pinion tool is reversed, it not only improves the finishing accuracy of the rack teeth, but also shortens the work time required for finish rolling. Excellent practical effects can be obtained.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of the finish rolling method for easy teeth, Figure 2
The figure is a schematic diagram showing the tooth profile of a rack tooth with finishing errors, Figure 3 is an explanatory diagram showing changes in the meshing point between the pinion tool and the rack tooth during finish rolling, and Figure 4 is the point shown in Figure 3. An explanatory diagram for explaining the operating state of the load at P4', FIG. 5 is an explanatory diagram for the occurrence of errors depending on the depth of cut, and FIG. 7
The figure is a graph showing changes in the depth of cut for each stroke. 10... Pinion tool, 12... Easy rough material,
14... Adjustment means, 15... Flywheel, t
...Amount of cut.

Claims (1)

[Claims] 1. A pinion tool for finishing the easy teeth is engaged and pressed against the rough rough material on which easy teeth have been formed, and the pinion tool is rotated while reciprocating in the direction of the pitch line of the rough rough material to finish the rough teeth. A method for finish rolling rack teeth, which comprises rotating a flywheel together with the pinion tool and reducing the amount of cut into the rack material by the pinion tool each time the pinion tool is reversely moved.