JP5480683B2 - Helical gear machining method - Google Patents

Description

  The present invention relates to a method for machining a helical gear by a cutter, and more particularly, to create a machining specification that suppresses the generation of ghost noise, and to perform gear cutting with a combination of an appropriate number of gear teeth and cutter number. The present invention relates to a helical gear machining method.

When creating a tooth surface of a gear, a tooth profile is formed in a gear cutting step of cutting the gear blank material while relatively moving the gear blank material and the cutting tool. As the cutting tool, a hob cutter, a pinion cutter or the like is used.
When processing with a combination of a gear blank material and a cutting tool, generally, the final tooth profile is not formed, and since a minute scaly unevenness (tool mark) remains on the tooth surface, a tooth surface finishing process is necessary. In this tooth surface finishing process, tooth surface finishing is performed by gear grinding using a shaving cutter or a screw-type grindstone to improve tooth surface roughness, ensure tooth surface accuracy, and reduce gear noise.

  Here, the normal gear noise is generally generated at a gear meshing order and an integer multiple thereof, and is perceived as sound or vibration. Good, gives a sense of discomfort to normal gear sound. Therefore, in order to suppress a ghost sound, a technique for improving the surface roughness by grinding the tooth surface is known (for example, Patent Document 1).

  Further, by collecting vibration data of the rotating body and performing frequency analysis, it is possible to determine whether the gear is engaged or not (for example, Patent Document 2), or to measure each tooth surface shape in a plurality of simultaneous contact line directions of the gear. A technique is known in which the tooth surface shape of a helical gear is measured by setting the meshing direction based on the apex of the actually measured tooth surface shape (for example, Patent Document 3).

JP 2000-52145 A JP-A-2-38930 Japanese Patent Laid-Open No. 11-118407

However, Patent Document 1 is a processing technique for eliminating a ghost sound by tooth surface grinding of a gear that generates a ghost sound, and does not focus on the problem of suppressing the ghost sound in a gear cutting process by a cutter.
Patent Document 2 and Patent Document 3 disclose measurement and analysis techniques for tooth surface shapes, and what is the problem of creating a gear cutting processing specification with a cutter for preventing the occurrence of ghost noises in advance? Not disclosed.

  The present invention has been made in view of such a background, and has created a machining specification that suppresses the occurrence of ghost noise, and performs helical cutting with a combination of an appropriate number of gear teeth and cutter strips. It is an object of the present invention to provide a gear machining method.

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that the number of teeth of a helical gear is Z, the number of cutters cutting the tooth surface of the gear is H, an arbitrary positive integer is N, and the balance An integer part is represented by M, and Z = H × N + M, a specification determination step for determining whether or not M = ± 1 is satisfied, and Z> H so that none of M = ± 1 is satisfied. M1 corresponding to N1 which is the largest integer among N satisfying × N is M1> 1, and M corresponding to N2 which is the smallest integer among N satisfying Z <H × N M2 is found looking contains and a toothed step for gear cutting in combination of two conditions are satisfied the number of teeth Z and the number of threads H of the M1 and M2 that is M2 <1,
In the gear cutting step, Z = H × N + M,
M1 satisfies one of the following conditions: M1 = + 2, +3,..., + (N−2),
The M2 satisfies one of the conditions of M2 = −2, −3,..., − (N−2),
And (N-2) is (N-2) ≦ H-2.
It is the processing method of the helical gear by the cutter characterized by being.

  According to the first aspect of the invention, there is a high possibility that a ghost sound is generated by including a specification determination step that determines whether or not M = ± 1 is satisfied, expressed as Z = H × N + M. By determining whether or not the machining specifications are satisfied, it is possible to avoid the machining specifications that are likely to generate ghost sounds.

  That is, when the tool mark of the cutter formed on the tooth surface of the gear is verified in the combination of the number of teeth Z and the number of stripes H satisfying any one of M = ± 1, it is sequentially performed along the feed direction of the cutter. , Tool marks formed by adjacent blade portions (individual cutters from the first line to the H line) having different line numbers are arranged.

  On the other hand, since the center axis is eccentric as an individual difference or the center axis is displaced when it is attached to the gear cutting machine, the cutter inevitably occurs within the allowable limit of machining accuracy. Under the influence of the above, it is assumed that the blade portions (tooth portions from the first line to the H line) of the respective line numbers form tool marks having slightly different cutting depths.

  However, the effect of eccentricity of the shaft, etc., is due to the difference in the cutting depth of the tool mark formed by the tooth part of the adjacent line number in a cutter with a large number of lines, so that one difference between adjacent tooth surfaces is different. When the tool marks having the line numbers are arranged, tool marks having slightly different cutting depths are continuously arranged, so that a swell having continuous smooth regularity is formed on the tooth surface. Further, the effect of the undulation on the ghost sound will be described later.

  Therefore, by determining whether or not M = ± 1 is satisfied, it is determined whether or not there is a high probability that a swell having continuous smooth regularity that affects the ghost sound is formed on the tooth surface. By determining with a simple method and avoiding the formation of the undulation that affects the generation of the ghost sound, the generation of the ghost sound can be suppressed in advance.

  In the gear cutting step, gear cutting is performed with a combination of the number of teeth Z and the number of teeth H satisfying the two conditions of M1> 1 and M2 <1 so that none of M = ± 1 is satisfied. By doing so, it is possible to avoid the formation of the undulations so that the tool marks with different streak numbers adjacent to the tooth surface are not lined up, and effectively suppress the generation of ghost noise at the stage of gear cutting. be able to.

For this reason, since it is possible to effectively avoid unexpected ghost sounds by using a simplified and simple method, an extra polishing process or the like for eliminating the ghost sounds becomes unnecessary, and man-hours are eliminated. It can contribute to reduction.
In the present invention, for example, when the number of cutters is 4, the gears are cut by a combination of the number of gear teeth and the number of cutters satisfying the condition of Z = 4 × N ± 2, and the number of cutters is 5 In the case of strips, gears are cut by a combination of the number of gear teeth and the number of cutter strips satisfying the condition of Z = 5 × N ± 2 or Z = 5 × N ± 3. , Z = 6 × N ± 2, or Z = 6 × N ± 3, or Z = 6 × N ± 4.

The invention according to claim 2 is the helical gear machining method according to claim 1 , wherein the number H of the cutters is four or more. According to such a configuration, it is possible to more efficiently suppress the generation of a ghost sound by eliminating in advance combinations in which the number H of cutters having a high possibility of satisfying any of M = ± 1 is 3 or less. be able to.

  According to this configuration, for example, when the number of cutter strips is four, gears are cut by a combination of the number of gear teeth and the number of cutter strips satisfying the condition of Z = 4 × N ± 2, and the number of cutter strips is determined. Is 5 gears and the number of teeth of the cutter satisfying the condition of Z = 5 × N ± 2 or Z = 5 × N ± 3, and the number of cutters is 6 In this case, gear cutting is performed by a combination of the number of gear teeth and the number of cutters satisfying the condition of Z = 6 × N ± 2, Z = 6 × N ± 3, or Z = 6 × N ± 4.

The invention according to claim 3 is the helical gear machining method according to claim 1, wherein the number of teeth Z and the number of stripes H satisfy the two conditions of M1 and M2 in the gear cutting step. Guiding means is provided so that the above conditions can be recognized.
According to such a configuration, the operator can quickly and surely recognize the combination condition of the number of teeth Z and the number of stripes H that satisfy the two conditions M1 and M2.

The invention according to claim 4 is the helical gear machining method according to claim 3 , wherein the guide means displays the combination conditions by voice guidance, a list, a card, a display, and a list. It is any one described and displayed in the above. According to such a configuration, the operator can quickly and reliably determine the combination condition of the number of teeth Z and the number of stripes H satisfying the two conditions of M1 and M2 by the guidance means displayed by voice guidance, a list, or the like. Can be recognized.

  The present invention can provide a processing method of a helical gear that creates a processing specification that suppresses the generation of ghost noise and performs gear cutting with a combination of an appropriate number of gear teeth and cutters.

It is a perspective view which shows the mode of a general gear cutting process, (a) shows a mode that a gear is processed while sending a cutter from the bottom up, (b) shows the number of teeth of 5 cutters, a gear, Conceptually shows the relationship. It is a figure for demonstrating the state of the tool mark formed in the tooth surface at the time of processing a gear with 44 teeth with a 5-thread cutter, (a) is an arrangement order of the tool mark in each tooth surface. (B) conceptually shows the state of undulation formed on the tooth surface, and (c) is a side view schematically showing a state in which the rotation center of the cutter is deviated. It is a schematic diagram of a tooth surface for explaining a tooth contact state when an R tooth surface is accelerated when a right-handed helical gear and a left-handed helical gear mesh with each other, and (a) is a right-handed helical gear. Clockwise, (b) shows a state in which the left helical gear rotates counterclockwise. It is a schematic diagram of a tooth surface for explaining a tooth contact state when an L tooth surface is accelerated when a right-handed helical gear and a left-handed helical gear mesh with each other, and (a) shows a right-handed helical gear. Counterclockwise, (b) shows a state in which the left helical gear rotates clockwise. It is a schematic diagram for demonstrating the state of the tool mark formed in a tooth surface, (a) is a fragmentary perspective view of the tooth surface of a gearwheel, (b)-(d) is relative of the cutting amount of each line | wire of a cutter. It is a conceptual diagram which shows a difference. It is a figure for demonstrating the state of the tool mark formed in the tooth surface at the time of processing a gear with 44 teeth with 6 cutters, (a) is an arrangement order of the tool mark in each tooth surface (B) conceptually shows the state of undulation formed on the tooth surface, and (c) is a side view schematically showing a state in which the rotation center of the cutter is deviated. It is a figure for demonstrating the state of the tool mark formed in the tooth surface in the case of processing a gear with 44 teeth with a 3 piece cutter. It is a figure for demonstrating the state of the tool mark of the other example in the case of processing a gear with the number of teeth of 44 teeth with a 3 piece cutter. It is a table | surface for demonstrating the relationship between the combination of the number of teeth, the number of strips, and a ghost sound. It is a typical perspective view for demonstrating the part for 1 tooth meshing in a gearwheel. It is the figure which analyzed the relationship between the number of tool marks and a ghost order, (a) is processing a 44-tooth gear with a 5-thread cutter, (b) is processing a 49-tooth gear with a 6-tooth cutter. Show the case. It is a figure for demonstrating the relationship between the eccentricity of a cutter, and a ghost sound, (a) is sectional drawing which shows a mode that a cutter is eccentric, (b) is the extent of the eccentricity of a cutter, and a ghost sound. It is a graph which contrasts.

  A gear machining method according to an embodiment of the present invention will be described using a left-twisted helical gear as an example and compared with machining specifications with high probability of generating ghost noise.

  In general, when gear cutting is performed from a workpiece BL (gear blank material) with a cutter 2 such as a hob cutter or a pinion cutter, the cutter 2 is moved in the direction A shown in FIG. 1A. Then, while rotating at a high speed, it feeds in the B direction (gear width direction) illustrated from the top to the bottom and gears while rotating the workpiece BL. After completion of gear cutting, the cutter 2 is released in the C direction, moved in the D direction, and returned to the machining origin.

  And, for example, in the case of a 5-thread cutter 2, as shown in FIG. 1 (a), convex blade portions 2a arranged continuously in a spiral shape from the first thread to the fifth thread, 2b, 2c, 2d, 2e (2a to 2e) are formed. For this reason, when processing the gear 3 having the number of teeth of Z with five cutters, as shown in FIG. 1B, the tooth surfaces 3a, 3b, 3c are formed by the convex blade portions 2a to 2e. , 3d, 3e (3a to 3e) are cut, and the first tooth 3A, the second tooth 2B, the third tooth 3C, the fourth tooth 3D, the fifth tooth 3E,... Is done.

  A gear machining method according to an embodiment of the present invention includes a specification determination step for determining whether or not a combination of the number of gear teeth and the number of cutter stripes is likely to generate ghost noise, and an appropriate gear tooth And a gear cutting step for gear cutting with a combination of the number and the number of cutters.

  The specification judging step represents Z = H × N + M, where Z is the number of gear teeth, H is the number of cutters cutting the gear tooth surface, N is an arbitrary positive integer, and M is the remaining integer portion. In this step, it is determined whether or not any of M = ± 1 is satisfied.

The specification determination step will be specifically described by taking as an example a case where a 44-tooth gear is processed with cutters (hob cutters) having 5, 6, and 3 cutters, respectively.
Here, when the number of cutters is 5, since 44 = 5 × 9-1 in Z = H × N1 + M, the condition of M = M2 = −1 is satisfied. Therefore, with this combination, it is assumed that there is a high probability that a ghost sound is generated.

When the number of cutters is 6, since 44 = 6 × 7 + 2 in Z = H × N + M, M = M1 = 2 and 44 = 6 × 8−4, so M = M2 = -4.
Therefore, since none of M = ± 1 is satisfied, it is assumed that the probability that a ghost sound is generated is low in this combination.

  When the number of cutters is 3, since 44 = 3 × 15−1 in Z = H × N1 + M, the condition of M2 = −1 is satisfied. Therefore, with this combination, it is assumed that there is a high probability that a ghost sound is generated.

  Then, in the undulation shape determination step, it can be seen that when the undulation forms a continuous smooth single wave having an approximate period close to a sine curve, or M = ± 1. In addition, when either of M = ± 1 is satisfied, it can be seen that the swell forms a continuous smooth single or equi-cycle swell close to a sine curve.

[For 5 teeth with 44 teeth]
In the specification determining step, a case where a gear having 44 teeth is cut with a cutter having 5 threads will be described with reference to FIGS. FIG. 2A to be referred to shows the arrangement order determination step, and tool marks formed on each tooth surface from the first tooth of the gear (the column of the number of teeth 1) to the 44th tooth (the column of the number of teeth 44). Are arranged in the vertical direction. In addition, the bottom row of the table is sequentially displayed such that the rotation of the work BL (see FIG. 1A) is rotated on the first round, and the top is rotated on the second turn of the work BL. FIG. 2 (b) shows the undulation shape determination step, and conceptually shows the undulation of the concavo-convex shape formed on the tooth surface in consideration of the difference in the cutting depth of each strip along the tool mark arrangement order. It is.

  The lowermost part of the table shown in FIG. 2A displays 1 as the tool mark formed on the first line of the cutter from the first tooth described in the leftmost tooth number 1 to the 44th tooth in the right direction. The tool mark formed in the second line of the cutter is displayed as 2. In the first rotation of the workpiece BL, since the first to fifth teeth of the gear are formed from the first to fifth teeth of the cutter, they are displayed as tool marks 1 to 5. Similarly, the sixth tooth to the tenth tooth of the gear are respectively formed from the first to fifth stripes of the cutter and are displayed as tool marks 1 to 5. Then, the 44th tooth is the tool mark 4 formed in the 4th line.

Thus, when the workpiece BL makes one rotation, the cutter is sent along the tooth surface in the width direction of the gear during that time (see FIG. 1A), so the first tooth following the 44th tooth is the fifth tooth. A tool mark for the line is formed. That is, the tool mark 5 is formed on the first tooth adjacent to the tool mark 1 (see the second step from the bottom of the first tooth).
As described above, in the first tooth, the gear cutting process is repeated while repeating the tool marks 1, 5, 4, 3, 2 in this order from the bottom of the table.

  Here, as shown in FIG. 10, a one-tooth meshing length δ in the direction along the width direction of the gear is set, and the number T of tool marks included in this one-tooth meshing length δ is considered as a reference. To do. The one-tooth meshing length δ is a concept representing the meshing length corresponding to the main tooth contact of the gear.

The helical gear is a cylindrical gear that is a winding with helical teeth, and the helical winding with a reference cylindrical shape has a twist of β. When the gear rotates once, it advances by the lead Pz in the direction along the width direction of the gear. Therefore, the tooth meshing length δ is represented by δ = Pz / Z, where d is the reference circle diameter and m is the tooth right angle module, Pz = πd / tanβ, so δ = π × m ÷ sinβ Can be obtained.
Specifically, if m = 1.74 and the twist angle is β = 36 degrees, the length δ of one tooth meshing is δ = 3.14 × 1.74 ÷ 0.588≈9.30 mm.

Therefore, the number T of tool marks included in the one-tooth meshing length δ can be obtained from T = δ / V, where V is the cutter feed speed.
For example, if V = 1.5 mm / s, the number T of tool marks included in one tooth meshing length δ is T = 9.3 ÷ 1.5 = 6.2. 6 tool marks in the central part of the are extracted and considered.

Here, the tooth contact state when the helical gear is driven will be described with reference to FIGS. 3 and 4. 3 and 4 are diagrams for explaining the twisting direction, the rotational direction, and the tooth contact direction depending on the difference between the driven gear and the driving gear in the helical gear. FIG. 3 is a left-handed twist, and FIG. 4 is a right-handed twist. Indicates.
3 and 4, the Top side indicates a side to which a driving device such as an engine is connected, the Bottom side indicates a side to which a driven device such as a transmission is connected, and the rotation direction is clockwise or counterclockwise as viewed from the Top side. Indicates clockwise. Further, the root part is indicated as Root, and the tooth tip part is indicated as Tip.

  For example, as shown in FIG. 3, when a right-handed helical gear is driven to rotate clockwise as viewed from the Top side (see FIG. 3A), the counterclockwise helical gear to be paired is counterclockwise. Following rotation (see FIG. 3B). In this case, the R tooth surface is the tooth contact surface for both gears, and the right-handed helical gear, as shown in FIG. 3A, is from the bottom tooth root Root to the top tooth tip Tip. Progresses diagonally on teeth. As shown in FIG. 3 (b), the pair of left-handed helical gears advances in a diagonal manner from the bottom-side tooth tip Tip to the top-side tooth root Root in a diagonal line.

  By the way, for example, when the above gear set is incorporated in a mission assuming a car engine, a mission, and driving wheels, the rotation does not reverse. That is, when the engine speed is increased, the right-twisted helical gear is used as a drive gear, and the left-twisted helical gear is used as a driven gear. When the vehicle decelerates, the engine speed decreases, but the driving wheel rotates, so this time the left-handed helical gear is used as the driving gear, and the right-handed helical gear is used as the driven gear. Meshes and rotates.

That is, even if the functions of the drive gear and the driven gear are changed by both gears in the above process, the rotation direction is not changed.
Therefore, as shown in FIG. 3, when the left-twisted helical gear rotates counterclockwise (see FIG. 3B), the paired right-twisted helical gear rotates clockwise (see FIG. 3). 3 (a)), the L tooth surface of both gears becomes the tooth contact surface, and the helical gear of the left-handed twist is shown in FIG. 3 (b) from the root side root portion Root to the Top side tooth tip portion. The tooth progresses diagonally to Tip. As shown in FIG. 3A, the pair of right-handed helical gears advances in a diagonal manner from the bottom-side tooth tip Tip to the top-side tooth root Root in a diagonal line.

On the other hand, the example of FIG. 4 in which the rotation is in the opposite direction to the example of FIG. 3 will be described.
When the right-handed helical gear is rotated counterclockwise as viewed from the Top side (see FIG. 4A), the pair of left-handed helical gears is rotated in a clockwise direction (FIG. 4B). )reference). In this case, the L tooth surface of both gears becomes the tooth contact surface, and the helical gear with right-handed twisting, as shown in FIG. 4 (a), from the top root portion Root to the bottom tooth tip portion Tip. Progresses diagonally on teeth. The pair of left-handed helical gears advances in a diagonal manner from the top-side tooth tip Tip to the bottom-side tooth root Root in a diagonal line.

  When the left-handed helical gear rotates clockwise, the paired right-handed helical gears rotate counterclockwise, and both gears have the R-tooth surface as the tooth-contact surface, and the left-handed helical gear. The gear advances diagonally from the top side root portion Root to the bottom side tip portion Tip on a diagonal line. As shown in FIG. 4B, the pair of right helical gears advances in a diagonal manner from the top-side tooth tip Tip to the bottom-side tooth root Root in a diagonal line.

  When a normal vehicle is assumed, the structure is not a structure in which the rotation is reversed, but in general, there is a structure in which the rotation is reversed. For example, in a motor-driven gear box, the direction of rotation can be freely controlled. However, as is clear from a comparison between FIG. 3B and FIG. 4B, when the rotation is reversed, the meshing order of the teeth and the meshing direction on each tooth surface are reversed, and similar results are obtained. Become. Therefore, the present invention does not need to limit the direction of rotation, and does not exclude a structure capable of reverse rotation.

Hereinafter, the continuity of the tool mark formed on the tooth surface when a 44-tooth helical gear having a left-handed twist is machined with a 5-cutter will be described in detail.
When the left-twisted helical gear is rotated counterclockwise as a driven gear, the tooth contact advances in the direction of arrow F as shown in FIG. 5A (see FIG. 3B). Therefore, focusing on the six tool marks included in the tooth meshing length δ, the range is surrounded by a thick frame. In the first tooth, the tool mark is downward from the paper surface along the tooth width direction. 1, 2, 3, 4, 5, and 1 (see FIG. 5A).

  Similarly, in the second tooth, as shown in FIG. 5 (a), the tool mark of the first tooth is processed by the next item number, so the arrangement order is the same as that of the first tooth. Marks 1, 2, 3, 4, 5, 1 and 6 tool marks in the same range as the first tooth, when viewed from the top down, tool marks 2, 3, 4, 5, 1, 2 line up. On the third tooth, the tool marks 3, 4, 5, 1, 2, 3 are arranged.

Here, in FIG. 5A, since the streak number is not unique and the connection of the streak number is important, for convenience of explanation, the first tooth contact portion within the one-tooth meshing length δ in the first tooth The range in which the article number is 1 is extracted and considered.
Further, the actual tooth contact proceeds in the direction of arrow F, but the arrangement order of the tool marks is the same even if considered along the tooth width direction. Considering the tool marks in line.

On the other hand, the cutter is inevitably subject to eccentricity of the central axis as an individual difference and deviation of the central axis when attached to the gear cutting machine within the allowable limit of machining accuracy (see FIG. 12).
For this reason, in actual gear cutting, assuming that the rotation center C1 of the cutter is displaced toward the first tooth portion 2a (see FIG. 1) with respect to the center axis C2 of the cutter, FIG. As shown in b), the cutting depth of the second article is deeper than that of the first article (processing by the teeth of the first article), the third and fourth articles are further deepened, and the fifth article is The depth of cut is the same as in Article 2.

  When the relative difference of the cutting depth for each cutter stripe number is displayed on the graph, as shown in FIG. 2B, the tool marks 1, 2, 3, 4, 5, 1 are present on the first tooth. (FIG. 2 (a)), the difference in cutting amount between the tool mark 1 and the tool mark 2 and the difference in cutting amount between the tool mark 2 and the tool mark 3 are equal and the steps are small, so that it has continuous smoothness. Yes. And since the cutting amount of the tool mark 3 and the tool mark 4 is the same, it has smooth continuity. Furthermore, since the difference in cutting amount between the tool mark 4 and the tool mark 5 is the same and the step is small, it has continuous smoothness, and since the difference in cutting amount between the tool mark 5 and the tool mark 1 is equal, smooth continuity is also achieved. Have.

  For this reason, in the arrangement order of the tool marks 1, 2, 3, 4, 5, 1 on the first tooth, the tool marks are continuously arranged with few steps, and this change is repeated at the same cycle. A single or equi-periodic undulation (equal-period undulation) having continuous smooth regularity is formed on the tooth surface.

  Similarly, since the second tooth and the third tooth have the same arrangement order of the first tooth and the tool mark, the same period swell is formed in the same manner, and the fourth tooth to the 44th tooth are the same. An equal period swell is formed. In this way, since the arrangement order of the tool marks is the same from the first tooth to the 44th tooth, a similar equal period swell having the same regularity is formed.

  It is assumed that the equi-periodic swell having regularity common to all the tooth surfaces (from the first tooth to the 44th tooth) has a high probability of affecting the ghost sound. And it turns out that such an equal period waviness is formed when either M = ± 1 is satisfied.

[In case of 6 teeth with 44 teeth]
A case where a gear having 44 teeth is cut with a cutter having 6 threads will be described mainly with reference to FIG. The bottom row in the table of FIG. 6 is displayed as tool marks 1 to 6 because the first to sixth teeth of the gear are formed from the first to sixth teeth of the cutter, respectively. The 44th tooth is the tool mark 2 formed in the second line.

  In this way, when the workpiece BL (gear blank material) makes one rotation, the cutter is sent along the tooth surface in the width direction of the gear during that time (see FIG. 1A), so the first following the 44th tooth. The tooth has a third tool mark 3 (see the second step from the bottom of the first tooth).

  Therefore, with the first tooth, the gear cutting is repeated while repeating the tool marks 1, 3, 5, 1, 3, and 5 in this order from the bottom of the table (see FIG. 6A). On the other hand, on the second tooth, tool marks are formed so as to repeat in order of tool marks 2, 4, 6, 2, 4, 6 from the bottom of the table, and on the third tooth, tool marks 3, 5, 1, 3 , 5 and 1 are repeated. As described above, the arrangement order of the odd-numbered first teeth and the third teeth is the same, but the arrangement order of the odd-numbered first teeth and the even-numbered second teeth is different.

  Here, paying attention to the six tool marks included in the one tooth meshing length δ, the first teeth are aligned with the tool marks 1, 5, 3, 1, 5, 3 from top to bottom ( (See FIG. 6 (a)). On the other hand, the second teeth are aligned with tool marks 2, 6, 4, 2, 6, 4, and the third teeth are aligned with tool marks 3, 1, 5, 3, 1, 5.

  Then, in consideration of the relative difference in the cutting amount for each cutter strip number, as understood from FIG. 6 (c), the second and sixth items rather than the first item are compared to the first item. The amount of cut is deeper in the line, the third and fifth are deeper, and the fourth is the deepest cut.

When the relative difference of the cut amount for each cutter stripe number is displayed on the graph, as shown in FIG. 6B, the first teeth are in the order of tool marks 1, 5, 3, 1, 5, 3. (FIG. 4 (a)), since the difference in cutting amount between the tool mark 1 and the tool marks 5 and 3 is relatively large, the level difference is large and the continuous smoothness is lacking.
Similarly, since the second teeth are in the order of 2, 6, 4, 2, 6, 4 (FIG. 6A), the difference in the cutting amount between the tool marks 2 and 6 and the tool mark 4 is large. The steps are relatively large and lack continuous smoothness.

  Moreover, the uneven undulations formed on the odd-numbered first teeth are uneven and formed on the even-numbered second teeth, whereas the tool marks 1 are shallow and the tool marks 5 and 3 are deep. Swelling is deeper than tool mark 1 in tool marks 2 and 6, and the tool mark 4 is deeper than tool marks 2 and 6, so the uneven shape and depth are different. I don't have it. Therefore, it is considered that the probability that a ghost sound is generated is low because an equal period swell having regularity (equal period) common to all tooth surfaces does not occur.

[For 3 teeth with 44 teeth (6 tool marks)]
A case where a gear having 44 teeth is cut with a cutter having 3 threads will be described mainly with reference to FIG.
The bottom row in the table of FIG. 7 is displayed as tool marks 1 to 3 because the first to third teeth of the gear are formed by the first to third teeth of the cutter, respectively. The 44th tooth is the tool mark 2 formed in the second line.
In this way, when the work BL rotates once, the cutter is sent along the tooth surface in the width direction of the gear during the rotation (see FIG. 1A), so the first tooth following the 44th tooth is the third tooth. The tool mark 3 of the line is formed (see the second step from the bottom of the first tooth).

  Therefore, with the first tooth, the gear cutting process is repeated while repeating the tool marks 1, 3, 2, 1, 3, 2 from the bottom of the table (see FIG. 7A). On the other hand, the arrangement order of the second teeth is the same as that of the first teeth, but starts with the tool mark 2 shifted from the first tooth by one, and the tool marks 2, 1, 3, 2, 1, Tool marks are formed so as to be repeated in the order of 3, and the third tooth starts with the tool mark 3 further shifted by one and repeats in the order of the tool marks 3, 2, 1, 3, 2, 1.

  As described above, although there is a deviation, the arrangement order of the tool marks is the same for all teeth except for the difference between the start end and the end, so that it has regularity (equal periodicity) common to all tooth surfaces, etc. Periodic undulation occurs.

Focusing on the six tool marks included in one tooth meshing length δ, the first teeth are aligned with tool marks 1, 2, 3, 1, 2, 3 from top to bottom (FIG. 7 ( a)). The second tooth is aligned with tool marks 2, 3, 1, 2, 3, 1 and the third tooth is aligned with tool marks 3, 1, 2, 3, 1, 2.
Then, in consideration of the relative difference in the cutting amount for each cutter strip number, as understood from FIG. 7 (c), the second and third items rather than the first item are compared with the first item. The amount of cut is deeper in the line.

  When the relative difference of the cutting amount for each cutter stripe number is displayed on the graph, as shown in FIG. 7B, in the first tooth, the difference between the cutting amounts of the tool mark 1 and the tool marks 2 and 3 is large. Although lacking in continuity, it has equi-periodicity. Similarly, in the second tooth and the third tooth, the difference in cutting amount between the tool marks 2 and 3 and the tool mark 1 is large and lacks continuous smoothness. Since the arrangement order of the marks is the same, it has the same regularity (equal periodicity) common to each tooth.

  Therefore, it is not appropriate to determine that the probability of occurrence of ghost noise is low. Avoid such processing specifications and change to processing specifications with low probability of ghost noise generation, or management of cutter eccentricity, etc. It is desirable to take measures in advance, such as stricter accuracy control and increasing the machining allowance for finishing.

[For 3 teeth with 44 teeth (7 tool marks)]
Here, when the cutter feed speed V is decreased and the number of tool marks included in one tooth meshing length δ is adjusted to be 7, the graph of the relative difference in the cutting depth for each cutter line number becomes As shown in FIG. 8B, the first teeth are aligned with the tool marks 1, 2, 3, 1, 2, 3, 1 (see FIG. 8A). The second tooth is aligned with tool marks 2, 3, 1, 2, 3, 1, 2, and the third tooth is aligned with tool marks 3, 1, 2, 3, 1, 2, 3.

  When the swell of the 6 tool marks displayed in FIG. 7B and the swell of the 7 tool marks displayed in FIG. 8B are compared, the swell of the 7 tool marks is greater than the swell of the 6 tool marks. Since the regularity (regularity) on the tooth surface is improved, the regularity common to each tooth surface is increased, and therefore, the probability that a ghost sound is generated is assumed to be higher.

  Thus, by adjusting the feed speed V of the cutter, the length of the tool mark in the feed direction is changed, so that the period of the equal period swell formed on each tooth surface is changed, the adjacent tooth surface is Since the continuity of the periodic undulation changes, it is assumed that the magnitude of the ghost sound and the probability of occurrence of the ghost sound are different.

Note that the number of teeth Z divided by the number H is divisible as in the case of cutting a gear with 44 teeth with a cutter with 2 or 4 threads, and when Z = H × N + M, M = 0 There is a case.
In the case of such a combination, the tool mark 1 by the first line is formed on the tooth surface of the first tooth, and the tool mark 1 by the second line is formed on the tooth surface of the second tooth. In this way, the unique characteristics of the cutter stripe number are all reflected on the specific tooth surface. For this reason, since it is a combination that is usually not adopted, the above-described equal period swell does not occur, but a detailed description of such a combination is omitted.

  Based on the above results, the relationship between the number of teeth of the gear and the number of strips of the cutter is summarized as shown in FIG. FIG. 9 shows the relationship between the number of teeth and the number of strips when gears having 10 to 49 teeth are cut with a cutter having two to six strips. In Z = H × N + M, M = ± 1 is described.

  “O” in the table is a combination that does not satisfy M = ± 1 and is unlikely to generate a ghost sound, and “indication of 1 and −1” in the table indicates that M = ± 1. It is a combination that satisfies any one and is assumed to have a high probability of generating a ghost sound, and the “display of 0” in the table is a combination that is desirably avoided because it is a combination in which M = 0.

Here, as can be seen from FIG. 9, in the case of the two and three cutters, an appropriate combination does not occur.
In this way, the combination of the number of teeth Z and the number of teeth H satisfying the two conditions of M1 and M2 is displayed in a list as a guide means so that the operator can quickly recognize on the site. Is effective.
In addition to the list, the guidance means can be displayed on a card, displayed in bullets, or can be guided by voice when the display operator presses an activation button.

  In the gear cutting step, M1 which is M corresponding to N1 which is the largest integer among N satisfying Z> H × N so that M = ± 1 is not satisfied, and M1> 1. The number of teeth Z and the number of strips satisfying the two conditions of M1 and M2 that M2 which is M corresponding to N2 being the smallest integer among N satisfying Z <H × N is M2 <1 This is a step of gear cutting with a combination of H.

  Specifically, M1 = + 2, +3,..., + (N-2) is satisfied, and M2 = -2, -3,...,-(N-2) is satisfied. And, the above (N1-2) adopts a combination of the number of teeth Z and the number of stripes H so as to satisfy (N1-2) ≦ H-2.

  Next, the generation pattern of the ghost sound in the case where the 44-tooth left helical gear is cut with a 5-cutter will be mathematically examined. As shown in FIG. 11, an integer is taken as the number of tool marks, and the number of teeth 44 is made to correspond to a place corresponding to 5 of 5 cutters. 44 ÷ 5 = 8.8 is placed next to the number of tool marks 1 to correspond, and a multiple of 8.8 is sequentially placed for each integral multiple of the number of tool marks. In this way, 35.2 corresponds to the number 4 of tool marks, and 52.8 corresponds to the number 6 of tool marks.

  In consideration of the fact that 44-tooth gear noise is generated in the 44th order and its integral multiple, this fact is 35.2nd when the number of tool marks is 4, 35th order in the integer expression, and the number of tool marks is 6th. That is, it is suggested that a 52.8th order ghost sound is generated in the case of 6 tool marks and a 53rd order ghost sound is generated in the integer expression.

  Furthermore, if a ghost sound is generated with an integer multiple of the number of cutter stripes, for example, a pattern with the number of cutter stripes minus 1, the order of the ghost sound is 35th order (35.2), 79th order (79.2), 123 Next (123.2), if a ghost sound is generated in the pattern of the number of cutter stripes + 1, the order of the ghost sound is 53th order (52.8), 97th order (96.8), 141st order (140.140). 8).

  Here, when gears with 44 teeth are cut with a cutter with 5 threads, since M2 = -1, it is set when the cutter runout is actually 10μ and 120μ. In this way, it is determined whether or not a ghost sound is generated.

  As a result of collecting the vibration measurement data of the gears by the bench test and analyzing the order of whether or not a ghost sound is generated, as shown in FIG. The peak was observed. Therefore, it can be seen that a ghost sound derived from the 53rd-order amplitude is generated. Since the amplitude peak is clearer at 120 μ than at 10 μ, it is assumed that the ghost sound also increases.

The gear machining method according to the embodiment of the present invention has the following operational effects.
That is, it is expressed as Z = H × N + M, and it is determined whether or not the machining specification has a high possibility of generating a ghost sound by including a specification determination step for determining whether or not M = ± 1 is satisfied. Thus, it is possible to avoid in advance a machining specification that is likely to generate a ghost sound.

  For this reason, since it is possible to effectively avoid unexpected ghost sounds by using a simplified and simple method, an extra polishing process or the like for eliminating the ghost sounds becomes unnecessary, and man-hours are eliminated. It can contribute to reduction.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications.
For example, in the above-described embodiment, it is determined whether or not any of M = ± 1 is satisfied in the specification determination step, but the specification determination step specifically includes 1 of the cutter on each tooth surface of the gear. An arrangement order determining step for determining the arrangement order of the tool marks formed by each line from the line to the H line, and the center axis and the rotation axis of the cutter in the tool mark formed by each line In consideration of the difference in the cutting depth due to each of the strips due to the eccentricity (displacement), the uneven shape (swell) of the tooth surface formed by continuously arranging the tool marks becomes a sine curve An undulation shape determination step for determining whether to form a single or equi-periodic undulation (equal-period undulation) having continuous smoothness (small steps) that is close; It can be configured with a.

2 Cutter 3 Gear N Arbitrary positive integer M Remaining integer part H Number of cutters Z Number of gear teeth m Teeth right angle module δ Length of one tooth meshing β Torsion angle

Claims (4)

Z = H × N + M, where Z is the number of teeth of a gear that is a helical gear, H is the number of cutters that cut the tooth surface of the gear, N is an arbitrary positive integer, and M is the remaining integer part.
A specification determination step for determining whether or not any of M = ± 1 is satisfied;
Do not satisfy any of M = ± 1
M1, which is M corresponding to N1, which is the largest integer among N satisfying Z> H × N,
M1> 1 and
M2, which is M corresponding to N2, which is the smallest integer among N satisfying Z <H × N,
A gear cutting step for gear cutting with a combination of the number of teeth Z and the number of threads H satisfying the two conditions of M1 and M2 that M2 <1;
Only including,
In the gear cutting step, Z = H × N + M,
M1 satisfies one of the following conditions: M1 = + 2, +3,..., + (N−2),
The M2 satisfies one of the conditions of M2 = −2, −3,..., − (N−2),
And (N-2) is (N-2) ≦ H-2.
A method for machining a helical gear, characterized in that:   The helical gear machining method according to claim 1, wherein the number H of cutters is four or more.   The guide means is provided so that the condition of the combination of the number of teeth Z and the number of threads H satisfying the two conditions of M1 and M2 in the gear cutting step can be recognized. The processing method of the described helical gear. 4. The helical device according to claim 3 , wherein the guidance unit is one of voice guidance, display in a list, display on a card, and display in a bulleted list. 5. Gear processing method.

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