JP2023095160A - Gear and cutting tool - Google Patents

Abstract

To provide a gear that are difficult for humans to perceive as noise during engagement rotation.SOLUTION: A gear comprising a plurality of teeth, where the plurality of teeth 11, 11, ... arranged in succession form a set G, has an intentional difference in the shape of the teeth 11 when comparing adjacent tooth 111 and tooth 112 in the set G, and/or has an intentional difference between a pitch of the teeth 111 and a pitch of the teeth 112. The gear has one set or multiple sets of such sets G.SELECTED DRAWING: Figure 2

Description

The present invention relates to gears, and more particularly to tooth shape and tooth pitch.

For example, Patent Document 1 is known as a technique for reducing noise when gears mesh with each other. In Patent Literature 1, quietness is satisfied by improving tooth flank precision.

JP 2012-096251 A

By the way, conventionally, in addition to Patent Document 1, it is believed that improving the finishing accuracy of the dimensions related to the shape of the teeth is good for reducing noise and vibration during meshing. To briefly explain this point, FIG. 10 is a graph schematically showing conventional gear meshing noise (gear noise), where the horizontal axis represents frequency and the vertical axis represents sound vibration (vibration and vibration sound). show. With reference to FIG. 10, it can be understood that sound vibration increases at frequencies at regular intervals. This is because there is uniformity in the time difference between the teeth in order, and this frequency is called the gear meshing frequency f, which depends on the number of teeth z of the gear, and is obtained by the following equation. Sound vibrations with frequencies that are integral multiples of this frequency are called integer-order noises, and sound vibrations with frequencies that are non-integer multiples are called non-integer-order noises.
[Formula 1] f = N/60 x z
f: gear meshing frequency [Hz] N: gear rotation speed [rpm] z: number of gear teeth [sheets]

When the gear noise shown in FIG. 10 is input to a person's ear, it cannot be said unconditionally whether or not the person perceives the gear noise as unpleasant noise due to complex factors such as environment and individual differences. , at least the integer-order tones shown in FIG. 10 are likely to be perceived by the human brain and easily recognized as noise. The reason for this is thought to be that the gap between the noise peak of integer-order noise and the noise bottom of non-integer-order noise is large.

Aiming for gear noise that is difficult for humans to perceive, the present inventors focused on the gap between the noise peak of integer-order noise and the noise bottom of non-integer-order sound (hereinafter also referred to as the noise gap), and made the noise gap smaller. and came to the present invention.

To this end, the present invention provides a multi-toothed gear comprising a set of teeth arranged in succession, such sets having differences in shape and/or pitch of adjacent teeth, We have one or more repetitions of such a set.

According to the present invention, the plurality of teeth does not have a uniform shape and a uniform pitch as in the prior art, but there is a significant difference between the teeth that constitute the set. Non-uniformity occurs in the time difference between meshing. As a result, as shown in FIG. 9, the non-integer order noise becomes larger and the noise gap becomes smaller. Further, the meshing sound generated when the gear of the present invention rotates while meshing with the mating gear is less likely to be perceived as noise even if it enters human ears. Regarding the gear of the present invention, the pattern of the plurality of teeth forming the set is not particularly limited. The set is repeated in the circumferential direction of the gear.

The difference between a plurality of teeth forming a set is at least one of various control items. For example, a plurality of teeth forming a set may have different tooth flank profiles or tooth trace shapes. Specifically, for example, at least one of the tooth profile gradient, tooth profile unevenness, and other shapes in the tooth profile of the tooth surface may have a difference. Alternatively, for example, there may be a difference in at least one of the tooth trace inclination in the tooth trace shape, the crowning center position, the amount of crowning, or other shapes. Further, the teeth forming the set may have different pitches, and more specifically, they may have different control items such as single pitch, adjacent pitch, or cumulative pitch. In addition, the uneven tooth profile in the tooth profile of the tooth flank refers to forming the tooth flank so as to be rounded, for example, when the tooth is viewed in the axial direction of the gear, and is also called tooth profile rounding or tooth profile crowning. The crowning in the tooth trace shape means that in the tooth trace extending from one axial end to the other in the axial direction of the gear, the center region of the tooth trace bulges when viewed from both ends of the tooth trace. In the gear according to the present invention, since a plurality of teeth constituting one set have differences from each other, the differences are patterned within one set, and the patterned differences have reproducibility. According to the present invention, by repeating the set in the manufacturing process of the gear, the sets have reproducibility such that the sets have the same regularity, so that the gear can be produced efficiently.

The present invention also provides a gear-shaped cutting tool having a plurality of cutting teeth, wherein the plurality of cutting teeth arranged in succession constitutes a set, and the adjacent cutting teeth of the set differ in shape and/or pitch. and one or more iterations of such a set.

Each shape and each pitch of a plurality of cutting teeth forming a set in the cutting tool are managed by the same management items as the gears described above.

According to the cutting tool of the present invention, a gear having teeth arranged in the circumferential direction with different teeth can be efficiently manufactured by honing, skiving, gear shaping, or shaving.

Thus, according to the present invention, the gap between the noise peak of the integer-order noise and the noise bottom of the non-integer-order noise is smaller than in the conventional art, and the noise peak of the integer-order noise is masked, resulting in a rotating gear pair. Even if the meshing sound enters the human ear, it is difficult to perceive it as noise and vibration. Moreover, the cutting tool of the present invention enables mass production of the gear of the present invention. The gear of the present invention is suitably used for passenger cars with high quietness performance such as electric cars.

It is a front view showing a gear which becomes a 1st embodiment of the present invention. It is an enlarged view extracting and showing the set of teeth of the same embodiment. It is a graph which shows the accumulation pitch significant difference of the same embodiment. It is an enlarged view extracting and showing the set of teeth of the same embodiment. 4 is a graph showing test results of the magnitude of sound and vibration for Example 1 and Comparative Example 1. FIG. FIG. 10 is an enlarged view showing the contour shape and control dimensions for one tooth in relation to the second embodiment of the present invention. 10 is a graph showing test results of the magnitude of sound and vibration for Example 2 and Comparative Example 2. FIG. 1 is a front view showing a cutting tool according to one embodiment of the present invention; FIG. 4 is a graph showing the magnitude of sound vibration according to the present invention; 2 is a graph showing the magnitude of sound vibration in the prior art;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a front view showing a gear that is one embodiment of the present invention. The gear 10 of the present invention is an external gear with a plurality of teeth 11 on its outer circumference. The number of teeth 11 is 40, including 8 as a divisor of the number of teeth. Eight consecutive teeth form one set corresponding to the divisor. Such one set is repeated five times in the circumferential direction of the gear 10 . As a modification not shown, the gear of the present invention may be an internal gear. Also, the number of teeth forming a set and the number of sets forming a gear may be changed arbitrarily.

To add here, in general gears, the number of teeth of each gear does not have a common divisor other than 1 so that the teeth of one gear and the teeth of the other gear mesh with each other in a round-robin manner. is preferred, and prime numbers are often used for the number of teeth. In the present invention, the number of teeth constituting one set is used as a divisor for the number of teeth of the gear, and in addition, the number of sets constituting the gear is used as a divisor of the number of teeth of the gear.

2 is an enlarged view of a set of teeth extracted from the gear shown in FIG. 1; FIG. As described above, one set G is composed of 8 teeth, which is the same as 8, which is a divisor. The pitches of the teeth in one set G are not all made uniform, but contain intentional variations (significant differences) that exceed manufacturing tolerances such that they differ slightly with dimensional differences that are imperceptible to the naked eye. In order to facilitate understanding of the invention, significant differences are exaggerated in FIG. 2 and other embodiments (FIGS. 4 and 6) described below. It should be noted that in FIG. 2 the teeth of the conventional gear pitch are drawn in dashed lines. The tooth pitches of conventional gears are all made equal within a given tolerance.

As shown in FIG. 2, when the teeth 11 among the teeth 11 constituting one set G are compared, all the teeth 11 are not uniform but have intentional differences. Specifically, there is a significant difference in the pitch of the teeth 11 . Referring to FIG. 2, comparing the pitches of the circumferentially adjacent teeth 111, 112, 113, it can be seen that there is a significant dimensional difference between the two. In this embodiment, it is managed by the cumulative pitch. The cumulative pitch significance difference in this embodiment is represented by cumulative pitch significance differences Pa, Pb, Pc, Pz, Py, Px, and Pw, with one tooth having a cumulative pitch significance difference of 0 as a reference. Referring to FIG. 2, the cumulative pitch is obtained from the intersection of one tooth flank of one tooth 11 serving as a reference and the pitch measurement circle Cs on the circumference of the pitch measurement circle Cs. is the arc distance to the intersection of the tooth surface and the pitch measurement circle Cs, and the cumulative pitch significant difference is a numerical value indicating how much it differs from the standard cumulative pitch. The standard cumulative pitch is the cumulative pitch when all adjacent tooth pitches are equal. The pitch measurement circle Cs is a circle having a smaller diameter than the addendum circle and a larger diameter than the root circle, and coaxial with the arrangement of the teeth 11 . Conventional teeth, still represented by dashed lines, are arranged at a standard cumulative pitch. As a modified example (not shown), the one tooth used as the reference for the cumulative pitch significant difference may be another tooth.

In this embodiment, the cumulative pitch significance difference has intentionally adjusted regularity. Specifically, as shown in the graph of FIG. 3, the cumulative pitch significant differences Pc, Pb, Pa, 0, Pz, Py, Px, Pw of the teeth 11, 11, . is patterned according to an arbitrary function. All the teeth 11 of the gear 10 are arranged to repeat a plurality of sets (for example, 5 sets) with this pattern as one set. The cumulative pitch significance of this embodiment is regular based on a sine wave as shown in the graph of FIG. The form of patterning is freely set. The magnitude relationship of Pc, Pb, Pa, 0, Pz, Py, Px, and Pw is freely determined between the maximum and minimum values. For example, some numbers among Pc, Pb, Pa, 0, Pz, Py, Px, Pw may be equal. For example, Pc=Pa, Pw=0, and Pz=Px. The pattern of patterned differences is not limited to the sine wave illustrated in FIG. It may have regular, random variations, or other patterns.

The gear 10 of the present invention may be managed by the cumulative pitch shown in FIG. 3 described above, or may be managed by a single pitch shown in FIG. 4 or adjacent pitches (not shown). FIG. 4 is a diagram showing single pitches Pe, Pf, Pg, Ph, Pi, Pj, Pk, Pl of teeth 11, 11 . . . forming one set G, and corresponds to FIG. Referring to FIG. 4, the single pitch is the arc distance between the intersections of the pitch measurement circle Cs and one of the circumferentially adjacent tooth flanks of the teeth 11 adjacent in the circumferential direction on the circumference of the pitch measurement circle Cs. The single pitch significant difference is a numerical value indicating how much it differs from the uniform standard single pitch Ps. A uniform standard single pitch refers to a numerical value obtained by dividing the total circumferential distance of the pitch measurement circle Cs by the number of teeth. Conventional gear teeth, still represented by dashed lines, are arranged at a uniform standard single pitch.

The single pitches Pe, Pf, Pg, Ph, Pi, Pj, Pk, Pl also have deliberately adjusted regularities. For example, as shown in FIG. 3, it is a sine wave, and there is a difference when comparing adjacent single pitches. Referring to FIG. 4, it can be seen that the teeth 11 of this embodiment, unlike conventional gears, have significant dimensional differences from a uniform standard single pitch.

In the embodiment shown in FIG. 4, the difference between the maximum and minimum values is a predetermined value within the range of 5-100 μm. Such a difference is, of course, larger than the manufacturing tolerance of the gear 10 . The same applies to the difference between the maximum value and the minimum value in the embodiment shown in FIG. 2 and FIG. 6, which will be described later. If the difference between the maximum value and the minimum value exceeds 100 μm, it is not preferable because of durability problems such as abrasion. Also, if the difference between the maximum value and the minimum value is less than 5 μm, the noise gap becomes large, that is, it becomes almost the same as the conventional one, which is not preferable.

A prototype of the embodiment of the present invention indicated by the solid line in FIG. 2 was made (Example 1). Also, a gear with a uniform pitch was prepared as indicated by the dashed line in FIG. 2 (Comparison 1). Then, a comparative test of the sound and vibration levels of Example 1 and Comparative Example 1 was carried out. For the cumulative tooth pitch of Example 1, the difference between the maximum and minimum values is 30 μm. With respect to the tooth cumulative pitch of contrast 1, all tooth cumulative pitches are standard cumulative pitches. Common items of Example 1 and Comparative Example 1 are that the diameter of the addendum circle of the gear is 85 mm, the diameter of the root circle is 73 mm, the face width is 20 mm, and the cumulative pitch that is the target value for manufacturing and the actual cumulative pitch. is 10 μm or less. The mating gear meshed with Example 1 and the mating gear meshed with Contrast 1 are common gears, and are gears with a conventional general standard cumulative pitch. While meshing with the mating gear, it was rotated at a rotational speed of 500 rpm, and the meshing noise and vibration was measured. At the same time, the meshing sound was confirmed by human ears.

FIG. 5 is a graph showing the measurement results of meshing noise and vibration. In the graph, the horizontal axis represents frequency [Hz], and the vertical axis represents the magnitude of meshing noise vibration [dB]. It can be seen that Example 1 (solid line) has larger non-integer-order noise than Comparative Example 1 and has a smaller noise gap. When confirmed by human ears, contrast 1 sounded louder than example 1.

Next, a second embodiment of the invention will be described. FIG. 6 is a front view showing the second embodiment, and is an enlarged view showing teeth that make up one set. In FIG. 6, (A) represents a set of teeth 11, and (B) represents the difference of each tooth 11 in comparison. In the second embodiment, regarding the plurality of teeth 11 forming the gear 10, the tooth profile shape of each tooth 11 is slightly varied, that is, given a significant difference.

As a specific example, the control item that makes the tooth profile shape different is to make the tooth profile gradient of the tooth profile 12 on the tooth flank of the tooth 11 different from each other, and the uncorrected shape calculated in the theoretical tooth profile curve, or With respect to the reference tooth profile 12s, which is a shape to which the amount of modification set by the designer based on the theoretical tooth profile curve is added, the tooth profile gradient of the actual tooth profile 12 is made steeper by a significant difference Sb, Sc, or Sa, or It is a design tooth profile that makes the tooth profile slope gentler by the difference Sb, Sz, or Sy. Then, the difference in tooth profile 12 of each tooth 11 is patterned in one set G.

The significant differences in the tooth profile gradients of the tooth flanks have intentionally adjusted regularity. Referring to FIG. 6A, significant differences Sc, Sb, Sa, 0, Sz, Sy, Sx in tooth profile gradients of tooth flanks of teeth 11, 11 . . . , Sw are patterned according to an arbitrary function. All the teeth 11 of the gear 10 are arranged to repeat a plurality of sets (for example, 5 sets) with this pattern as one set. The significant difference in tooth profile gradient in the tooth profile of the tooth flank of the present embodiment may be regular based on a sine wave as shown in the graph of FIG. In FIG. 3, Pc, Pb, Pa, 0, Pz, Py, Px, and Pw can be read as Sc, Sb, Sa, 0, Sz, Sy, Sx, and Sw, respectively. Note that some of Sc, Sb, Sa, 0, Sz, Sy, Sx, and Sw may be equal. For example, Sc=Sa, Sw=0, and Sz=Sx. The pattern of patterned differences is not limited to the sine wave illustrated in FIG. It may be a random tooth profile shape with significant differences, or other patterns.

From a control point of view, the significant differences Sc, Sb, Sa, 0, Sz, Sy, Sx, and Sw are the circumferential dimensions (linear length or arc length) in the measurement circle Cr between the tip circle Ct and the tooth profile control circle Cd. is. For example, the measurement circle Cr is a circle whose radius is a predetermined value within the range of 50 to 95% of the outer diameter side of the tooth profile control circle Cd, with the difference in radius between the addendum circle Ct and the tooth profile control circle Cd being 100%. The pattern of significant differences Sb, Sa, Sz, and Sy in one set G conforms to FIG. In order to facilitate understanding of the invention, FIG. 6 exaggerates the significant difference in tooth profile shape, and assumes that the measurement circle Cr is 100%.

In addition, when the lower limit value is less than 50%, the control range is too small and the noise gap, which is the subject of the present invention, is not sufficiently reduced. Moreover, when the upper limit value of 95% is exceeded, the management is not reflected in the actual product, and the noise gap, which is the subject of the present invention, is not sufficiently reduced.

The significant differences Sb, Sa, Sc, Sz, Sx, Sy are predetermined values within the range of 2 to 40 μm. Such a difference is, of course, larger than the manufacturing tolerance of the gear 10 . If the significant differences Sb, Sa, Sz, and Sy exceed a predetermined range, it is not preferable due to durability problems such as wear. I don't like it because it will end up being the same.

As a modified example (not shown), the management items that make the tooth profile different may be the tooth profile gradient of the tooth 11 or various other tooth profile management items classified under JISB1702 "tooth profile error". Alternatively, as another modified example (not shown), the tooth trace shape of the tooth 11 may be made different. Management items that make the tooth trace shape different are, for example, the crowning center position, the tooth trace inclination, other crowning, and other various tooth trace managements classified under JISB1702 "tooth trace error". It can be an item.

An embodiment of the present invention indicated by a solid line in FIG. 6(A) was experimentally produced (Example 2). Also, a gear with a uniform tooth profile was prepared as indicated by the dashed line in FIG. 6(A) (Comparison 2). Then, a comparative test of the sound and vibration levels of Example 2 and Comparative Example 2 was conducted. Common items of Example 2 and Comparative Example 2 are that the diameter of the addendum circle of the gear is 85 mm, the diameter of the root circle is 73 mm, the face width is 20 mm, and the error between the tooth profile that is the target value for manufacturing and the actual tooth profile. The amount (tolerance) is 10 μm or less. The mating gear meshed with the second embodiment and the mating gear meshed with the comparative gear 2 are common gears, and are conventional general gears with a uniform tooth profile. While meshing with the mating gear, it was rotated at a rotational speed of 500 rpm, and the meshing noise and vibration was measured. At the same time, the meshing sound was confirmed by human ears.

FIG. 7 is a graph showing the measurement results of meshing noise and vibration. In the graph, the horizontal axis represents frequency [Hz], and the vertical axis represents the magnitude of meshing noise vibration [dB]. It is understood that the non-integer-order noise is larger in Example 2 (solid line) than in Comparative Example 2, and the noise gap is smaller. When confirmed by human ears, comparison 2 sounded louder than example 2.

Next, a cutting tool for producing the gear of this embodiment will be described.

FIG. 8 shows a cutting tool 60 for cutting the gear 10 shown in FIG. The cutting tool 60 has the shape of an external gear and has cutting teeth 61 having a shape similar to that of a gear. As a modified example (not shown), the cutting tool of the present invention may have an internal gear shape.

A cutting tool 60 shown in FIG. 8, like the gear 10 described above, has a set of a predetermined number of cutting teeth as shown in FIGS. repeat. In the embodiment shown in FIG. 8, the total number of teeth is 40, the number of teeth in one set is 8, and 5 sets are repeated. In manufacturing the gear 10, the cutting tool 60 used in the finishing stage of high-precision cutting and grinding has a set of cutting teeth 61 of the same number as the number of teeth in the set of the gear 10. Multiple sets of cuts are repeated circumferentially.

The contour shape of the cutting teeth 61 corresponds to the teeth 11 described above. That is, the cutting teeth 61 have the shape of gear teeth made so that the contour shape of the trajectory drawn by the cutting teeth 61 when machining the gear matches the tooth 11, like a pair of gears meshing with each other. All cutting teeth 61 are patterned with regular differences as shown in FIG. 3, and adjacent cutting teeth 61, 61 are made to have slightly different shapes.

The cutting tool 60 rotates together with the gear to be machined while being pressed against the gear to be machined. At this time, the cutting tool 60 forms the teeth 11 of the set G by removing excess material from the surface of the gear to be machined, and more specifically by finish cutting, grinding, polishing and dressing. The cutting tool 60 is also called a dresser, grindstone, pinion cutter, or shaving cutter because it is used for gear honing, skiving, gear shaping, or shaving.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope. For example, a part of configuration may be extracted from one embodiment described above, another part of configuration may be extracted from another embodiment described above, and these extracted configurations may be combined.

INDUSTRIAL APPLICABILITY The present invention is advantageously used in mechanical elements.

10 gearwheel, 12 actual tooth profile of tooth flank (tooth profile gradient), 12s reference tooth profile, 60 cutting tool, 61 cutting tooth, Cs intermediate circle, G one set of teeth.

Claims (4)

A gear comprising a plurality of teeth,
A plurality of teeth arranged in succession is regarded as one set,
said sets having differences in the shape and/or pitch of said adjacent teeth;
A gear having one or more repetitions of said set. Said difference is
In the above shape, the tooth profile gradient in the tooth profile of the tooth surface, the tooth profile unevenness, the tooth trace inclination in the tooth trace shape, the crowning center position, the amount of crowning,
In the pitch, single pitch, adjacent pitch, cumulative pitch,
2. The gear of claim 1, wherein the difference is in at least one selected from: A gear-shaped cutting tool comprising a plurality of cutting teeth,
A plurality of the cutting teeth arranged in succession are regarded as one set,
the sets have a difference in shape and/or pitch of the adjacent cutting teeth;
A cutting tool having one or more repetitions of said set. Said difference is
In the above shape, the tooth profile gradient in the tooth profile of the tooth surface, the tooth profile unevenness, the tooth trace inclination in the tooth trace shape, the crowning center position, the amount of crowning,
In the pitch, single pitch, adjacent pitch, cumulative pitch,
4. The cutting tool of claim 3, wherein the difference is in at least one selected from:

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