JPS5816973B2 - Gear cutting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for cutting gears using a pinion cutter or a rack cutter.

Conventionally, machining methods using pinion cutters, rack cutters, hobs, and end mills have been used to cut cylindrical gears. However, in particular, for machining gears such as shoulder gears that cannot be machined with hobs, pinion cutters or end mills have been used. Machining with a rack cutter has high productivity and is the most frequently used machining method, but the gear cutting method with a pinion cutter or rack cutter, as is well known, processes gears by generating cutting. During the generation cutting process, the cutting edge of the cutter is involved in the generation of each tooth groove from the beginning to the end, so the cutting blade handles the cutting amount corresponding to the cutting position. This is due to wear around the corner of the cutting edge (hereinafter referred to as corner wear), which is unique to this type of cutter and is not seen in general milling tools.
is known to occur.

Now, taking a pinion cutter as an example, we will explain its creation mechanism in the first,
This will be explained based on FIG.

(In the case of a rack cutter, a transverse movement is applied instead of the rotational movement of the cutter, which will be described later, and the generating cutting mechanism is no different from that of a pinion cutter.

) As shown in Fig. 1, a pinion cutter 1 with 21 teeth and a gear 2 to be cut with Z teeth are set on a gear cutting machine (not shown),
The pinion cutter 1 and the workpiece gear 2 are rotated in opposite directions at a rotation ratio of 1:2, and the pinion cutter 1 repeats a reciprocating stroke in its axial direction (perpendicular to the plane of the paper). At the same time, the pinion cutter 1 moves in the X direction, and rough cutting is performed by giving a rough cutting depth that forms a tooth profile with a narrower tooth width than the desired regular groove tooth profile.

When the rough cutting is completed, a finishing depth of cut is subsequently applied to the finishing cutting, and a desired regular involute tooth profile is created on the gear 2 to be cut.

Similarly, this generating cutting is not completed one tooth groove at a time, but proceeds over the entire required tooth groove.

That is, while the pinion cutter 1 makes one or two revolutions while reciprocating in the axial direction, all the tooth spaces of the gear to be cut 2 are subjected to generation rough cutting, and while the pinion cutter 1 makes one to two revolutions, finishing cutting is performed. The desired regular tooth profile is created.

That is, to explain the process of creating one tooth groove based on FIG. 2, while one tooth groove 3 of the gear to be cut 2 rotates to the position of the adjacent tooth groove (one pitch), One cutting edge C reciprocates in its axial direction and slowly rotates at a constant rotation ratio to give a predetermined depth of cut.
acts sequentially from C1 to Cn, cutting progresses, and 1
Two tooth grooves 3 involutes are created.

As is clear from the figure, the cutting edge C is the left side edge (leading cutting edge), the right side edge (trailing cutting edge) T, and the outer peripheral edge O.
The part that is cut in the first half of the generation process has an asymmetrical U-shape as shown by the shaded area W1 in the figure, and is cut on three sides by the left and right side edges, T, and outer edge O. I understand.

In addition, the cutting thickness is very thin near the corner formed by the right side cutting edge T and the outer peripheral cutting edge 1. The chips cut into such a shape are At this time, the flow force of the chips differs depending on the difference in the cutting amount, so cutting by the leading cutting edge and the peripheral edge O, which have a large cutting amount, that is, a large flowing force, and the cutting edge O, which has a large cutting amount, and the chip flowing out, has a small cutting amount, that is, flows out. It compresses the chips produced by the trailing cutting edge with a small force, causing a so-called chip interference phenomenon near the corner formed by the trailing cutting edge and the peripheral cutting edge, and as a result, the chips produced by the trailing cutting edge are pushed back. The debris flows out through the gap formed between the cutting edge and the workpiece, and in the process of flowing out, the cutting edge, especially near the corner, is damaged.

On the other hand, in the latter half of the generation process, one-sided cutting is performed with only the trailing cutting edge T, as shown by the shaded area W2 in the figure, but at this stage the cutting thickness is thin, so the cutting edge touches the workpiece. A phenomenon in which the cutting edge does not penetrate sufficiently and crushes the rigid material, in other words, a friction phenomenon between the cutting edge and the workpiece material occurs, and this is a synergistic effect of the above-mentioned phenomenon of scraping of chips against the cutting blade due to interference of chips. This acts to accelerate the wear of the corners.

Based on the above-mentioned findings, the present inventors have achieved a method of avoiding the abrasion phenomenon, reducing not only the corner wear of the cutting blade but also the overall wear of the cutting blade, which in turn reduces tool costs, shortens the re-grinding time, and The present invention aims to provide a new gear cutting method that can reduce the number of tool changes.

The gist of the present invention to achieve the above object is to use a pinion cutter or a rack cutter whose teeth are thinner than a regular tooth profile, and to perform relative rotational movement between the cutter and the gear to be cut. , the canter performs a so-called generating cutting motion consisting of a relative reciprocating motion in the axial direction and a cutting motion, and acts on the gear to be cut in synchronization with each stroke of the relative reciprocating motion. A slight oscillation or reciprocating motion relative to the canter or the gear to be cut in a direction perpendicular to the reciprocating motion in the axial direction so that the leading side and the trailing side of the cutting blade alternately perform cutting action. The present invention relates to a gear cutting method characterized in that a desired tooth profile is created by applying a tooth profile.

That is, in the present invention, when generating a gear with a pinion cutter or a rack cutter, the gear of the cutter is made thin in advance, and the leading side and trailing side of the cutting blade are alternately cut during the generation process. The cutting blade of the conventional cutter performs cutting on three sides, but by cutting on two sides or cutting on one side, the flow of chips, that is, the discharge performance is improved, and the corner part of each cutting blade is cut. The purpose is to reduce wear and other wear.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be explained in detail based on the drawings, taking a pinion cutter as an example.

In FIG. 4, numeral 10 is a pinion cutter with a number of teeth Z3, which is thinner than the regular tooth profile, and numeral 11 is a gear to be cut with a number of teeth Z4.

Now, as shown in the figure, set the cutter 10 and the gear to be cut 11 on a gear cutting machine (not shown), and as in the past, set the cutter 10 and the gear to be cut 11 at different rotation ratios of 1:Z3/Z4. As the cutter 10 rotates in the X direction, the cutter 10 repeats reciprocating strokes in the direction perpendicular to the plane of the paper and advances in the X direction to make a cut. Cutter 1 in sync
0 is given a minute rocking motion in a direction perpendicular to the reciprocating motion in the axial direction.

That is, the cutter 10 is synchronized with its reciprocating stroke and swings left and right by an angle α for each stroke in a direction perpendicular to the reciprocating motion, so that the leading L/ of its cutting edge C' and the trailing side T' The cutting action is performed alternately to create one tooth groove 12.

Further, to explain this generation process in detail based on FIG.
rotates slowly at a constant rotation ratio with respect to the gear to be cut 11,
While reciprocating in the axial direction, a minute rocking motion with a turning angle α is applied in a direction perpendicular to the direction of the reciprocating motion in the axial direction in synchronization with each stroke of the reciprocating motion, and a predetermined As the depth of cut is applied, the leading side L' and the trailing side T' of the cutting edge CI, which has a tooth thickness thinner than the normal tooth thickness, act sequentially from C1' to Cf1, and cutting progresses. In other words, an involute of one tooth space 12 is created by alternately cutting on the leading side L/ and the trailing side T'.

As is clear from the figure, the part cut in the first half of the generation process is L-shaped as shown by the diagonal line indicated by V1 in the figure by double-sided cutting by the side blade and the peripheral blade on either the leading side or the trailing side. However, this is because the above-mentioned micro-oscillating motion is applied so that the trailing side T/ and the leading rule L/ of the cutting edge C', which has a tooth thickness thinner than the normal tooth thickness, act alternately. No.

On the other hand, in the latter half of the generation process, as shown in the shaded area (■2) in the figure, cutting is performed on one side of only the trailing cutting edge T/. When the blade performs double-sided cutting, the flow of chips and prompt evacuation are very good.

That is, as shown in FIG. 6, the chips resulting from the cutting state in which one of the side blades is displaced alternately left and right by the minute oscillating motion are mainly chips B1 cut by one of the side blades and chips B1 mainly cut by the outer peripheral blade. Chips B2 cut by
Therefore, chips are not ejected from the other side cutting edges.

This becomes even clearer when compared with FIG.

When chips are discharged in this condition, chips B1,
In B2, as shown by the arrow in the figure, the chips flow smoothly in the direction from which they are not discharged, and there is no chip interference and the abrasion phenomenon disappears, resulting in the above-mentioned corner wear. Of course, the overall wear of both side cutting edges will be reduced.

In addition, cutting is performed alternately by two-sided cutting between the outer peripheral edge and the trailing cutting edge, and two-sided cutting between the outer peripheral edge and the leading cutting edge.

Therefore, the cutting amount and the resulting cutting thickness per side tooth will be nearly twice that of the side blade using the conventional gear cutting method - 111 The greater the cutting amount per side tooth, the more reliable the cutting will be. As a result, the phenomenon of the cutting edge crushing the rigid material, that is, the abrasion phenomenon, is reduced, and this also reduces the wear of the cutting edge.

In the above-described embodiment, the cutter 10 is given a minute oscillating motion in the direction perpendicular to its axial reciprocating motion, but in order to carry out the present invention, it is necessary to It is only necessary to apply the relative rocking motion, and therefore, it is of course possible to apply the rocking motion to the gear 11 to be cut.

Further, the above-mentioned minute rocking motion is a minute swinging motion of the cutter 10 and the gear 11 to be cut at a pivot angle α around the axis of the cutter 10 and the cut gear 11, but the amount of displacement due to the rocking motion is is a very small amount, so even if the oscillating motion is approximated by a reciprocating motion with a displacement δ corresponding to the oscillating displacement as shown in Figure 7, the tooth profile shape of the product gear will not differ much. .

Furthermore, since the method of the present invention cannot be carried out with existing gear cutting machines, it is easier to apply reciprocating motion to them even if they are to be repaired.

As is clear from the above description, the present invention uses a pinion cutter or a rack cutter with teeth thinner than a regular tooth profile, and performs a normal generating cutting motion between the cutter and the gear to be cut. At the same time, in synchronization with each stroke of the relative reciprocating motion in the generating cutting motion, a slight rocking or reciprocating motion relative to the cutter or the gear to be cut in a direction orthogonal to the reciprocating motion in the axial direction. By applying motion, two-sided cutting is performed by the outer peripheral force of the cutting edge and the side cutting edge on either the leading or trailing side, which reduces the abrasion phenomenon caused by interference of chips and the cutting caused by the small amount of cutting. The friction phenomenon between the blade and the workpiece material is reduced, and as a result, the wear on the flank of the cutting edge, especially the corner wear, is significantly reduced, which in turn reduces tool costs, shortens re-grinding time, and reduces the number of tool changes. The economic effects of this, such as reductions, are enormous.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the conventional method for cutting gears using a pinion cutter, Fig. 2 is an explanatory diagram of the generation process by the conventional method, Fig. 3 is an explanatory diagram of chips produced by the conventional method, and Fig. 4 is an explanatory diagram of the cutting process of the present invention. An explanatory diagram, FIG. 5 is an explanatory diagram of the creation process by the uninvented method, and FIG. 6 is an explanatory diagram of chips generated by the method of the present invention.
FIG. 7 is an explanatory diagram showing another embodiment. 1, 10... Pinion cutter, 2, 11... Gear to be cut, 3, 12... Tooth groove to be created, c, c'... Cutting edge, L, L'... Leading cutting Blade, T, T'・
... Trailing cutting edge, oo'-... Peripheral cutting edge, W12w
2.B1゜B2...Cuts.

Claims (1)

[Claims] 1 Using a pinion cutter or rack cutter with a thinner tooth thickness than the regular tooth profile, the cutter and the gear to be cut are subjected to relative rotational motion, relative reciprocating motion in the axial direction, and cutting motion. At the same time, the leading side and the trailing side of the cutting blade of the cutter, which act on the gear to be cut in synchronization with each stroke of the relative reciprocating movement, alternately perform a cutting action. A gear cutting method characterized in that a desired tooth profile is created by applying relative minute rocking or reciprocating motion to the cutter or the gear to be cut in a direction orthogonal to the reciprocating motion in the axial direction so as to create a desired tooth profile.