JP2006281263A - Method for rolling gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling technique for a gear material, by which rolling technique, a gear product with an accurate tooth shape can be obtained. <P>SOLUTION: The gear material before rolling has such a tooth shape that when the whole depth is represented by hf, the dedendum from its pitch point toward its root side is represented by ht, and the addendum from its pitch point toward its outside diameter side is represented by hk, an approximately triangular projection is provided on the respective tooth flanks over the dedendum side and the addendum side so as to place its apex on the pitch point with its straight sides tilted. The gear material is rolled so as to satisfy the following expressions, 0.25ht≤b≤0.85ht, 0.25hk≤c≤0.85hk, 0.25ht≤d≤0.25hk, where "a" shows the full length of the projection including the pitch point, "b" shows the length of the projection on the dedendum side, "c" shows the length of the projection on the addendum side, and "d" shows the difference between the pitch point and the apex of the projection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for finish rolling a gear. More specifically, the present invention relates to a gear rolling technique for producing a product gear by finish rolling a material gear manufactured by sintering or the like.

  Conventionally, in the rolling of a gear having a uniform rolling allowance from the tooth root to the tooth tip, there is a tendency that the vicinity of the pitch point of the product gear tends to be recessed, and the rolling is not uniformly performed. In particular, in the case of a sintered gear, the tooth surface of the tooth profile is sometimes densified at the time of rolling, and there is a tendency to increase the rolling allowance. The rolling of the sintered gear itself is superior in cost to other molded gears, and the development of an effective molding method is desired.

  In particular, various rolling methods have been tried for gear rolling made of sintered metal, and many rolling techniques are known. For example, a rolling method in which a range of 20 to 70 μ is raised near the pitch point to form a rolling allowance (for example, see Patent Document 1). Also, a step for absorbing a surplus generated by rolling at the boundary between the temporary tooth surface and the tooth bottom surface by positioning the sintered gear having the temporary tooth surface and the tooth bottom surface outside the tooth bottom surface. After forming a pre-tooth shape on the outer periphery of the disk-shaped material with a rolling technique (see, for example, Patent Document 2) or a pre-formed tooth shape die, the tooth base corresponding to the tooth shape of the target tooth shape A rolling technique (for example, refer to Patent Document 3) in which a preliminary tooth shape is formed into a target tooth shape by using a die of a finish forming tooth shape formed into a shape is known.

Japanese Patent Publication No.54-23670 Japanese Patent No. 3401164 JP 2000-42673 A

  As described above, conventional measures have been taken to solve the problems in gear rolling. However, recently, high precision is required in various fields, and the gear rolling technology is no exception. Although there is a limit in the conventional rolling technology, higher accuracy is required. Although the rolling process is performed by a die, it is not necessarily formed uniformly along the rolling allowance.

  During rolling, a complex force such as a wave is generated on the tooth surface of the material gear. Although this analysis is theoretically performed as it is, it is often different when applied in practice, and experimental values are also required to grasp the optimum conditions. For this reason, the gear shape at the material stage before rolling has a great meaning so as to obtain the target tooth profile (product tooth profile) after rolling.

  The setting of the rolling allowance at the material stage depends on various conditions for rolling, for example, the size, shape, and position of the rolling allowance. The tooth profile of the target gear after rolling varies slightly depending on these conditions. For this reason, in actual rolling, the optimum processing method is repeatedly set while finding appropriate conditions. In particular, in the case of sintered gears, the denseness of the tooth surfaces is also required.

  Conventionally, the setting is performed while assuming the amount of indentation due to the sintered gear, but the shape after rolling is not necessarily accurate and ideal. In addition, the current situation is that it is not efficient in the setting of the rolling process. For example, if rolling is performed using different dies, for example, the cost is inevitably increased, and providing a concave portion on the tooth surface of the material gear also causes a reduction in strength.

Thus, there is no guarantee that the conventional method can be applied to all gears. The product gears are rolled to achieve the target tooth profile, and the development of efficient rolling technology is desired, with the versatility of setting the rolling allowance.
Based on the above technical background, the present invention has been developed by solving conventional problems and has achieved the following object.

  It is an object of the present invention to provide a method for rolling a gear that enables a product gear having an accurate tooth surface shape to be formed by rolling a material gear provided with a substantially triangular convex portion in the vicinity of the pitch point. On offer. Another object of the present invention is to provide a rolling method of a gear in which a rolling allowance, that is, a dimension of a convex portion is set by calculation, and can be rolled.

  The present invention takes the following means in order to achieve the object.

The gear rolling method according to the first aspect of the present invention has a similar tooth profile shape to the product gear, the total tooth depth dimension is hf, the tooth root dimension from the pitch point to the tooth root side is ht, and the tooth tip from the pitch point is the tooth tip. In the rolling method of the material gear, where the side tooth tip dimension is defined as hk,
The tooth surfaces near the pitch are configured with dimensions within the hf, ht, and hk, and the pitch points are apexes, and the tooth surfaces on the tooth base side and the tooth tip side are inclined in a straight line to have a substantially triangular shape. It is characterized by forming a convex part and rolling a material gear. The substantially triangular convex portion is an approximate shape and is not limited to a linear shape.

  The method for rolling a gear according to a second aspect of the present invention is the method according to the first aspect, wherein in the first aspect, the dimension of the convex portion is a total length including the pitch point, a is the tooth root side from the pitch point, and b is the tooth tip from the pitch point. The side is defined as c, and the shift between the pitch point and the apex of the convex portion is defined as d. Expression 0.25ht ≦ b ≦ 0.85ht, Expression 0.25hk ≦ c ≦ 0.85hk, Expression 0.25ht ≦ d It is characterized by rolling a material gear having a convex shape that satisfies ≦ 0.25 hk.

  The gear rolling method according to the third aspect of the present invention is the gear 1 according to the first aspect, wherein the material gear module is defined as m, and in the range of 0.25 <m <5, the teeth between the apex of the convex portion and the tooth surface A surface height dimension is defined as e, and a convex-shaped material gear is rolled so as to satisfy the expression 0.005 mm ≦ e ≦ 1.000 mm.

The rolling method of the gear of the present invention 4 is the present invention 1,
The material gear is heated and rolled in a temperature range of 200 ° C to 500 ° C. In particular, it is effective for densifying the tooth surface of the sintered gear.

  The gear rolling method of the present invention 5 is the same as the present invention 3, in which the tooth surface height dimension e between the apex of the convex portion and the tooth surface is 0.005 mm ≦ e ≦ 0 for the melted material gear. .200 mm, and 0.010 mm ≦ e ≦ 1.000 mm for a sintered material gear. The range of e is preferably 0.010 mm ≦ e ≦ 0.100 mm for the melted material gear, and 0.050 mm ≦ e ≦ 0.500 mm for the sintered material gear.

  As described above, according to the present invention, in setting the rolling allowance of the material gear, the rolling allowance is only formed by a convex portion having a simple configuration, and the shape setting can be easily defined by calculation. . For this reason, the efficiency of the rolling process is improved, and an accurate tooth profile shape is formed. Also, in terms of cost, there is no need to use different types of dies, and the rolling method does not increase the cost.

  Hereinafter, the details of the rolling method of the gear according to the present invention will be described. FIG. 1 is a partial sectional view of a tooth profile schematically showing a part of a tooth surface of a material gear. The feature of the material gear which is the object of the rolling method of the present invention is its tooth profile shape, which has a similar tooth profile shape of the product gear, with the upper part of the pitch point 3 as the vertex 2 and the tooth base side and the tooth tip side. A substantially triangular convex portion 1 is formed by inclining linearly on each tooth surface. The pitch point 3 refers to an intersection of the tooth surface connecting the tooth root and the tooth tip and the pitch circle S.

  That is, an intersection 5 that is linearly inclined and intersected from the vertex 2 to the tooth root side tooth surface 4, an intersection 7 that is linearly inclined and intersected from the vertex 2 to the tooth tip side tooth surface 6, and the vertex 2 The substantially triangular portion surrounded by the connected lines constitutes the convex portion 1. The material gear having such a tooth surface shape is rolled, and the tooth surface shape of the product gear after the rolling is made to be a regular tooth surface shape. As described above, it is known that the vicinity of the pitch point 3 tends to be recessed during rolling. The present invention is a technology constructed by taking into consideration the results of the experiment in addition to the conventional results.

  Next, the contents of the backing will be described. In comparison with the rolling method of the present invention, the rolling of a gear with a conventional tooth profile will be confirmed. That is, when a conventional flat tooth profile material gear without tooth profile modification is rolled with a conventional flat tooth profile tool without tooth profile modification, the tooth profile after the rolling is both tooth surfaces. In both cases, it was confirmed by an experiment that it has a concave shape as shown in FIG.

  This FIG. 5 shows a sintered alloy spur gear of module m = 3 for each radial tool indentation amount of 300 μm, 450 μm and 600 μm after rolling the standard gear after rolling with the standard tool. The tooth profile curve is shown. This is the same for both spur gears and helical gears. FIG. 6 shows a rolling amount distribution when the standard gear is rolled with a standard tool.

  As shown in FIG. 6, the actual rolling amount becomes very large in the vicinity of both the tooth surface, that is, the driven side and the follower side around the pitch point as shown in FIG. Both tooth surfaces show that the vicinity of the pitch point is greatly recessed. The physical reason for this phenomenon is that when the rolling position is in the vicinity of the pitch point, the material gear is in an engaged state as if sandwiched in the center of the tooth gap of the tool. Alternatively, the elastic deflection of the material and the tool increases as it approaches the tooth base.

  Further, as is apparent from FIG. 5, this center-recessed shape is slightly rounded in the vicinity of the apex, but has a substantially inverted triangular shape with the apex near the pitch point. On the other hand, if the material gear is rolled with a convex portion as a rolling allowance having the same shape as this inverted triangle, the intermediate convex state is gradually eliminated during rolling, and the optimum tool push-in position is reached. A substantially flat tooth profile is obtained for both tooth surfaces.

  Therefore, as described above, in the present invention, as described above, a substantially triangular convex portion is formed by inclining linearly on each tooth surface on the tooth base side and the tooth tip side with the pitch point as an apex. The linear inclination is not a straight line but a substantially linear shape. As can be understood from the rolling result of FIG. 5, the concave portion of the figure is shaped as an inverted tooth profile.

  The basic dimension of the gear is defined as follows, and the appropriate dimension of the convex portion 1 is defined from the correlation, that is, the proper rolling allowance is defined. In the material gear, the total tooth depth dimension is defined as hf, the tooth root dimension from the pitch point 3 to the tooth root side is defined as ht, and the tooth tip dimension from the pitch point 3 to the tooth tip side is defined as hk. By defining the basic dimensions of the material gear in this way, the convex portion 1 described above is constructed within the respective dimensions so that the convex portion 1 does not exceed the tooth depth.

  Furthermore, the dimension of the convex part 1 was defined as follows, and the shape of the appropriate convex part 1 was prescribed | regulated by the following formula | equation. That is, the dimension of the convex part 1 is a total length including the pitch point 3 is a, a tooth root side is b from the pitch point 3, a tooth tip side is c from the pitch point 3, and the pitch point 3 is The deviation of the convex portion 1 from the apex 2 is defined as d, and the expression 0.25ht ≦ b ≦ 0.85ht, the expression 0.25hk ≦ c ≦ 0.85hk, the expression 0.25ht ≦ d ≦ 0.25hk, It is prescribed to satisfy. The relationship between the dimension of this convex part 1 and the basic dimension of a tooth surface is as follows.

  That is, a ≦ hf, a = b + c, b ≦ ht, c ≦ hk, and the deviation d from the pitch point 3 is d ≦ b and d ≦ c. The material gear of the convex part 1 shape prescribed | regulated by this dimension is rolled. The shape of the convex portion indicates a physical limit, and setting the shape of the convex portion exceeding this does not make sense.

  Next, the tooth surface height of the convex portion 1 is defined by defining the height dimension from the tooth surface to the vertex 2 as e. This dimension e takes into account the rolling conditions of the gear, that is, the size of the material gear, the material of the material gear, the amount of pressing of the rolling tool in the radial direction or the tooth surface vertical direction, machining accuracy, etc. Is set. This requires a very cumbersome setting. In the present invention, this is simplified and a module that defines the size of the gear is set and defined as a parameter.

  The module was defined as m (unit: mm), and the value of e was defined as follows according to the material of the material gear according to the range of m. For example, when m is 0.25 <m <5 within a range frequently used in the automobile industry, it is defined as 0.005 mm ≦ e ≦ 1.000 mm. In this rule, 0.005 mm ≦ e ≦ 0.200 mm is defined for the melted material gear, and 0.010 mm ≦ e ≦ 1.000 mm for the sintered material gear. Preferably, 0.010 mm ≦ e ≦ 0.100 mm for the melted material gear, and 0.050 mm ≦ e ≦ 0.500 mm for the sintered material gear.

  Rolling of the material gear described above is performed in a relatively low temperature range of about 200 ° C. to 500 ° C. below the recrystallization temperature, that is, between the cold and the hot. In this finish rolling process, even at this temperature, the sintered gear can sufficiently densify the surface layer and increase the strength. Furthermore, the machining accuracy is improved even when compared with hot.

  Next, an embodiment will be described in which a material gear set in accordance with this rule is rolled into a product gear. In the description of this embodiment, the relationship between the material gear and the tool is defined by the configuration shown in FIG. That is, the tooth surface side of the material gear in the processing progress direction of the tool and the material gear is driven, and the tooth surface side of the material gear opposite to the processing progress direction of the tool and material gear is the follower. The results of this example are shown in FIGS.

  FIG. 3 is a diagram showing a comparison of tooth profile curves before and after rolling a molten material modified gear of module m = 3. The melted material gear is S45C (carbon steel). In addition, although it carried out about S55C (similarly carbon steel) and SCM415 (chromium molybdenum steel) about the melting material besides this, the same result was obtained. The data on the driven side and the follower side are shown in three steps for the tool push-in amount, and in both cases, it was confirmed that after rolling, the tooth profile was flat and highly accurate.

FIG. 4 is a diagram showing a tooth profile curve when a sintered material modified gear of module m = 3 is rolled. In this example, compression molding pressure: 686 Mpa (7 ton / cm ² ), sintering condition: 1150 ° C., 20 minutes, composition in nitrogen gas atmosphere, the composition is Fe (Bal.) + 0.06% C + 0. 55% Ni + 1.03% Mo + 0.2% Mn, average density after sintering: 700 g / cm ³ (1P1S material, which is a sintered material formed by one-time compression once sintered by Kobe Steel) Using. In the driven side and the follower side, data corresponding to the tool push-in amount is shown. In any case, it was confirmed that the shape was flat and highly accurate after final rolling.

FIG. 1 is a partial cross-sectional view schematically showing the tooth profile of a material gear. FIG. 2 is an explanatory diagram showing the positional relationship between driven and follower in the tooth profile. FIG. 3 is a diagram of the embodiment, and is a data diagram of a tooth profile curve showing a change in the tooth profile before and after rolling in the molten material modified gear. FIG. 4 is a diagram of the embodiment, and is a data diagram of a tooth profile curve showing a change in the tooth profile shape of rolling in the sintered material modified gear. FIG. 5 is a data diagram of a tooth profile curve showing a tooth profile after rolling when a standard gear is rolled with a standard tool. FIG. 6 is a data diagram showing a rolling amount distribution when a standard gear is rolled with a standard tool.

Explanation of symbols

1 ... convex
2 ... apex
3 ... Pitch point
4 ... tooth base side tooth surface 5, 7 ... intersection 6 ... tooth tip side tooth surface

Claims (5)

The product gear has a similar tooth profile, the total tooth depth is defined as hf, the tooth root dimension from the pitch point to the tooth root side is defined as ht, and the tooth tip dimension from the pitch point to the tooth tip side is defined as hk. In the rolling method of the material gear
The tooth surfaces near the pitch are configured with dimensions within the hf, ht, and hk, and the pitch points are apexes, and the tooth surfaces on the tooth base side and the tooth tip side are inclined in a straight line to have a substantially triangular shape. A method of rolling a gear, comprising rolling a material gear having a convex portion. In the rolling method of the gear according to claim 1,
The dimension of the convex part is a total length including the pitch point, a is a tooth base side from the pitch point, b is a tooth tip side from the pitch point, and a deviation between the pitch point and the apex of the convex part. Is defined as d and satisfies the formula 0.25ht ≦ b ≦ 0.85ht, formula 0.25hk ≦ c ≦ 0.85hk, formula 0.25ht ≦ d ≦ 0.25hk A method for rolling a gear, comprising rolling the gear. In the rolling method of the gear according to claim 1,
The module of the material gear is defined as m, and when 0.25 <m <5, the tooth surface height dimension between the apex of the convex portion and the tooth surface is defined as e, and the formula 0.005 mm ≦ e A rolling method of a gear characterized by rolling a convex-shaped material gear so as to satisfy ≦ 1.000 mm. In the rolling method of the gear according to claim 1,
The material gear is rolled while being heated to a temperature range of 200 ° C to 500 ° C. In the rolling method of the gear according to claim 3,
The tooth surface height dimension e between the apex of the convex portion and the tooth surface is defined as 0.005 mm ≦ e ≦ 0.200 mm for the melted material gear, and for the sintered material gear, A rolling method for gears, characterized in that 0.010 mm ≦ e ≦ 1.000 mm.

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