JP2015021569A - Reduction driven gear structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reduction driven gear structure in which a shaft member and a disk-like member are integrally manufactured through a hot-forging, the shaft member is formed with inner and outer spline teeth through a cold-forging and at the same time the disk-like member is provided with reduction driven teeth.SOLUTION: This invention relates to a reduction driven gear structure 100 in which a disk-like member A and a shaft member B coaxial with the disk-like member A are integrally arranged, the outer circumferential surface of the disk-like member A is provided with helical teeth 1, the upper inner circumference of a hole passing through a shaft center in a vertical direction is formed with inner spline teeth 2 through cold forging and a lower outer circumferential surface of the shaft member B is formed with outer spline teeth 4 through cold forging, characterized in that the shaft member B is extrusion formed with hot-forging.

Description

  The present invention relates to a reduction driven gear structure provided on the output side of a transmission. The reduction-driven gear structure of the present invention is obtained by integrally manufacturing a disk-shaped member and a shaft member penetrating up and down the center. Then, reduction driven teeth comprising helical teeth are provided on the outer peripheral surface of the disk-shaped member, inner spline teeth are formed by cold forging on the inner periphery above the shaft portion, and cold forging is performed on the outer peripheral surface of the shaft member. External spline teeth are formed. The reduction driven gear structure of the present invention is characterized in that the outer diameter of the outer peripheral helical teeth of the upper disk-shaped member is large and the shaft length of the lower shaft member is long.

  A large driving force shifted by the transmission mechanism is transmitted to the drive shaft via a reduction driven gear that meshes with the reduction drive gear. The driving force of the drive shaft is transmitted to the wheel via a hypoid drive gear that meshes with the subsequent hypoid pinion gear. Details of these configurations will be described with reference to FIG. The drive shaft 3 and the drive pinion shaft 11 provided on the output side of the transmission are configured on the same axis, and both are splined by a spline. A reduction driven tooth 1 made of helical teeth is provided on the transmission side of the drive shaft 3. Further, a hypoid pinion gear 12 that meshes with the hypoid ring gear is provided at one end of the drive pinion shaft 11. A relatively large driving force shifted by a mechanism in the transmission is transmitted to the drive shaft 3 via the reduction driven tooth 1 meshing with the reduction drive gear 13 and then transmitted to the drive pinion shaft 11 via the spline portion. Is done. The driving force of the drive pinion shaft 11 is transmitted to the wheels via the hypoid ring gear meshed with the hypoid pinion gear 12 and reaches the subsequent differential device 14.

  2. Description of the Related Art Conventionally, a reduction driven gear structure is obtained by individually manufacturing a disk-like member having reduction driven teeth made of helical teeth on the outer periphery and a shaft member penetrating the center up and down, and then combining them. Then, reduction driven teeth comprising helical teeth are provided on the outer periphery of the disk-shaped member, and inner spline teeth are provided above the shaft member and outer spline teeth are provided on the lower drive shaft. Several proposals have been made regarding the application of the reduction driven gear structure (Patent Documents 1 and 2). In these patent documents, details of the reduction driven gear structure are unknown, but a reduction driven gear structure in which a plurality of separately manufactured tooth members are combined is provided on the output side of the transmission. As a method of combining a disk-shaped member and a shaft member that penetrates the center thereof vertically, for example, at the part of the outer spline tooth provided on the drive shaft, the boss inner diameter part of a separate disk-shaped member is integrated by spline coupling There is what I did. In addition, there is a combination in which the drive shaft is combined by electron beam welding at the rim portion of the disk-shaped member.

JP 2002-87089 A JP 2005-331064 A

  As described above, the conventional reduction driven gear structure has the following problems.

  In the prior art, since the drive shaft and the disk-shaped member are combined by outer spline teeth formed by rolling, there is a problem in strength due to spline tooth defects due to rolling formation. In other methods, a rattling sound is generated when the same portion is connected to a wedge by a helical tooth. Also, electron beam welding is performed to integrate the drive shaft and the disk-shaped member, but there are problems with the reliability of the coupling, such as peeling and dropping. It is necessary to confirm the reliability of the conversion. In addition, since both the spline coupling and the integrated coupling by electron beam welding are combined together, problems of accuracy such as concentricity caused by the assembly method occur. That is, there is a problem of the coaxiality between the outer row of the reduction driven teeth and the outer spline teeth or the inner spline teeth. In addition, since the drive shaft and the disk-shaped member are separately manufactured and then combined, it must be moved from the gear cutting device to the welding device, which complicates the process and increases the cost. By the way, the reduction driven gear structure of the present invention has a large outer diameter of the outer peripheral helical teeth of the upper disk-shaped member and a long shaft length of the lower shaft member. Therefore, a press with a large forging pressure tonnage and a long forging stroke is required, and it is difficult to obtain a large-capacity press satisfying both.

  Therefore, the reduction driven gear structure of the present invention has been made by paying attention to the above-mentioned problems. The shaft member and the disk-shaped member are integrally manufactured by hot forging, and the shaft member is internally and externally manufactured. An object of the present invention is to provide a reduction driven gear structure in which spline teeth are formed by cold forging and reduction driven teeth are provided on a disk-shaped member. Further, the object of the present invention is to produce an integrated manufacturing without causing problems of accuracy such as the coaxiality of the assembly of the two members, that is, the coaxial of the reduction driven tooth row on the outer peripheral side and the spline tooth row on the shaft side. An object of the present invention is to provide a reduction driven gear structure that maintains accuracy such as degree. And even if the stroke length of the forging press is short, the forging method is devised to extend the shaft member long, and a gear structure having a large outer diameter of the helical teeth of the disk-like member is obtained. It is an object.

In recent years, with the advance of forging technology, gears of all shapes can be formed by forging and machining can be omitted. Therefore, the inventors focused on using the forging line formed by forging as it is, and obtained the knowledge that when the gear was prototyped without machining after cold forging, it was excellent in durability.
The reduction driven gear structure of the present invention is embodied based on such knowledge, and the invention of claim 1 includes a disk-shaped member and a shaft member coaxial with the disk-shaped member, A hole penetrates the shaft in the vertical direction, helical teeth are provided on the outer peripheral surface of the disk-shaped member, inner spline teeth are formed on the upper inner periphery of the hole, and an outer peripheral surface below the shaft member is formed. It is a reduction driven gear structure in which outer spline teeth are formed.
The invention of claim 2 is characterized in that, in addition to the above feature of the invention of claim 1, the helical teeth are formed by forging.
The invention of claim 3 is characterized in that, in addition to the above feature of the invention of claim 1, the helical tooth is formed by gear cutting.
According to a fourth aspect of the present invention, in addition to the above feature of the first aspect of the invention, a forged line by hot forging is formed in the vicinity of the outer peripheral surface of the shaft member, and an outer spline tooth is formed by cold forging on the outer periphery. The outer spline teeth are formed with forged lines by cold forging.

  According to the present invention, the reduction-driven gear structure is integrally manufactured by a disk-shaped member and a shaft member penetrating up and down the center. Then, reduction driven teeth comprising helical teeth are provided on the outer peripheral surface of the disk-shaped member, inner spline teeth are formed by cold forging on the inner periphery above the shaft portion, and cold forging is performed on the outer peripheral surface of the shaft member. External spline teeth are formed. Since the reduction driven gear structure of the present invention is an integral structure and does not form and assemble each tooth individually, the degree of concentricity between the outer helical teeth and the inner inner and outer spline teeth Accuracy is improved. Further, since the reduction driven gear structure of the present invention is an integral structure, no rattling noise is generated. That is, there is an effect of suppressing noise generation. In addition, it is advantageous in terms of strength because the shear bending moment at the root portion does not work as in the case of spline coupling or helical tooth coupling. In addition, since the shaft member is extruded by hot forging, a forged streamline is formed densely inside the outer peripheral surface of the shaft. And since a forge flow line is densely formed inside the outer spline teeth formed on the outer peripheral surface of the shaft portion, a gear having excellent tooth profile surface durability can be obtained.

1, showing an embodiment of the present invention, is a sectional view of a reduction driven gear structure. It is explanatory drawing of process No. 1 by hot forging same as the above. It is explanatory drawing of process No. 2 by hot forging and process No. 3 by hot forging same as the above. It is explanatory drawing of process No. 4 by hot forging and process No. 5 by machining same as the above. It is explanatory drawing of process No. 6 by cold forging and process No. 7 by cold forging same as the above. It is explanatory drawing of process No. 8 by machining and process No. 9 by cold forging same as the above. It is a schematic diagram which shows formation of the forge line in forging same as the above. It is a figure which shows a prior art example and shows the usage example of a reduction driven gear structure.

  Embodiments of the present invention will be specifically described below based on the embodiments of the present invention illustrated in the accompanying drawings.

  First, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an embodiment of the present invention and is a sectional view of a reduction driven gear structure. FIG. 2 is an explanatory diagram of process No. 1 by hot forging and process No. 2 by hot forging. FIG. 3 is an explanatory diagram of process No. 3 by hot forging and process No. 4 by hot forging. FIG. 4 is an explanatory diagram of process No. 5 by hot forging and process No. 6 by machining. FIG. 5 is an explanatory diagram of process No. 7 by cold forging and process No. 8 by cold forging. FIG. 6 is an explanatory diagram of process No. 9 by machining and process No. 10 by cold forging. FIG. 7 is a schematic diagram showing formation of forged lines in forging.

  A reduction driven gear structure according to the present embodiment will be described with reference to FIG. In the reduction driven gear structure 100, a disk-shaped member A and a shaft member B coaxial with the disk-shaped member A are integrally provided by forging. Reduction driven teeth 1 made of helical teeth are provided on the outer peripheral surface of the disk-shaped member A, and outer spline teeth 4 are formed on the outer peripheral surface of the drive shaft 3 below the shaft member B by cold forging. And the inner spline tooth | gear 2 is formed in the upper inner periphery of the hole 5 which penetrated the shaft center to the up-down direction by cold forging. In addition, a screw portion or the like is provided at the lower end portion of the drive shaft 3 as necessary. In summary, the reduction driven gear structure 100 according to the present invention is provided with the reduction driven teeth 1 on the outer peripheral surface of the disk-shaped member A, and in particular, the drive shaft 3 is extruded by hot extrusion forging and is formed at the upper end thereof. The inner spline teeth 2 are provided, and the drive shaft 3 is provided with outer spline teeth 4. And the hole 5 penetrates the axial center of the drive shaft 3 toward the downward direction. In this embodiment, the diameter of the helical teeth on the outer peripheral surface of the disk-shaped member is large, and the shaft member extends long downward. For example, the tip diameter of the helical tooth of the upper disk-shaped member is 150 mm, and the total length of the shaft member passing through the center is 170 mm as a whole.

The main steps in manufacturing the integrally formed reduction driven gear structure according to this embodiment will be described.
First, a short-axis cylindrical material obtained by cutting a cylindrical material suitable for a reduction-driven gear structure into a predetermined axial length by a billet shear is obtained. In this case, a steel material suitable for the transmission gear, such as SC steel, SCM steel, SNC steel, SNCM steel, SCR steel, etc., can be used as the material of the material. First, a short-axis cylindrical material is heated to, for example, 1150 ° C. and hot upset forging is performed to obtain a flat rough material, which is prepared for the following steps.
As shown in FIG. 2 (1) of process No. 1, the raw material W1 which approximates the shape of a product is obtained by hot forging. The material W1 is pressed by an upper die to form a convex portion W11 and a middle disc-like portion W12 that rise upward along the die shape, and the disc-like portion W12 is a large-diameter portion D2 that expands in the radial direction. Have At the same time, the shaft portion W13 extending downward is extruded into a rod shape to form a small diameter portion D1. In the hot extrusion molding of the small-diameter portion D1 portion, the hole of the die mold Q penetrates and the bottom is free and not closed. Therefore, the shaft part W13 becomes a flesh flow F while being pressed by the upper die, and is extruded and elongated in the downward direction. In the first hot forging first step, since the lower end of the hole of the die die Q is not closed in the mold structure, the surplus material of the rough material is pushed out to the pressurized trough, and the meat flow flows to the tip of the shaft portion W13. To charge. Normally, in the forging, there is no escape path for the meat flow, especially in the hot forging, but in the hot forging in this process, the meat flow is filled up to the tip part by deliberately providing the escape path for the meat flow. I was able to prevent it. If the tip of the hole of the die mold Q where the shaft portion is formed is closed, an air pool is formed, the meat flow is not filled, and a lack of thickness occurs. According to the above procedure, it was possible to make a corner to the tip portion of the shaft portion without causing a lack of thickness at the tip portion of the shaft portion W13.

Next, as shown in FIG. 3 (2) of the process No. 2, the rough material W1 is subjected to hot forging to form a concave inner diameter portion W21 in the center of the upper surface of the disk-shaped portion W12. A donut-shaped recess W22 is formed on the outer peripheral side. As a result, a rough material W2 is obtained in which a bowl-shaped burr W23 that protrudes outward from the large-diameter portion D1 of the disk-shaped portion W12 protrudes.
Further, as shown in FIG. 3 (3) as the process No. 3, a rough material W3 having a deep inner diameter portion W31 is obtained by hot forging the inner diameter portion W21 which is recessed at the upper central portion of the rough material W2. . As will be described later, the inner diameter portion W31 protruding upward is a pilot hole that forms the inner spline teeth in the reduction driven gear structure.
Next, as shown in FIG. 4 (4) as step No. 4, the outer burr W23 protruding outward from the large diameter portion D1 is trimmed and removed to obtain a W41 rough outer peripheral surface. Next, cold forging is performed on the shaft portion W13 and ironing is performed to obtain a coarse material W4 having a shaft portion W42 of the small-diameter portion D3 that is thinned.
FIG. 5 (5) shows step No. 5, machining the inner diameter portion W31 to obtain a rough material W5 having an inner diameter portion W51 having an inner diameter d1.

5 (6) of process No. 6, the inner diameter portion W51 is further deeply drilled by cold forging to obtain an inner diameter portion W61 having a smaller inner diameter d2. At the same time, a rough material W6 having a shaft portion W62 extended by an amount corresponding to the volume of the inner diameter d2 drilled downward by the same cold forging is obtained.
In Step No. 7 of FIG. 5 (7), the inner diameter portion W61 is further deeply drilled by cold forging to obtain an inner diameter portion W71 having a smaller inner diameter d3. At the same time, a rough material W7 having a shaft portion W72 extended by an amount corresponding to the volume in which the inner diameter d3 is further drilled downward by cold forging is obtained.
In FIG. 6 (8) of process No. 8, the inner diameter part W51 was machined to obtain an inner diameter part W81 expanded to the inner diameter d4, and the machine work was performed below to expand the diameter to the inner diameter d5. An inner diameter portion W82 is obtained. At the same time, the shaft portion W72 extending downward is machined to obtain a shaft portion W83 having a diameter reduced to the small diameter portion D5. Then, a smaller inner diameter d6 is drilled by machining so as to penetrate the shaft core in the vertical direction. Or the rough material W8 which the hole of the internal diameter d6 penetrated by the deep drilling by cold forging and the end by punching is obtained.
In FIG. 6 (9) of process No. 9, the shaft part 83 is drawn by cold forging as follows using the inner diameter d6 drilled so as to penetrate the shaft core in the vertical direction. When the inner diameter d6 is deeply drilled by cold forging, the shaft end of the shaft W83 extends downward by the volume of the drilled hole. Alternatively, when drilling is performed by machining, a mandrel is inserted into the inner diameter d6, and the coarse material W8 is closed from above and below and from the circumferential direction by a mold. From the bottom, the back pressure BP is applied by the lower mold, while the pressure UP is applied by the upper mold from above. At this time, the shaft portion 83 is reduced in diameter, and the shaft end portion of the shaft portion W83 extends downward by the volume. Thus, by providing through the inner diameter d6, the shaft portion 83 could be gradually extended downward by cold forging while using a press having a short stroke. At this time, since the back pressure BP was applied from the lower side by the lower mold, the inner diameter part d6 could be tightly stretched. For example, there was no dent on the inner peripheral surface of the inner diameter part d6. Finally, the inner spline teeth 2 are formed on the inner diameter portion W81 by cold forging, and the coarse material W9 is similarly obtained by forming the outer spline teeth 4 on the shaft portion W83 by cold forging. Then, helical teeth 1 are formed on the rough outer peripheral surface W41 (see FIG. 1).

  There are three methods for forming the helical tooth 1, which is formed by machining or forging. When forming by the first machining, helical teeth are formed by gear shaper processing after step No. 9. Alternatively, the helical teeth may be formed only by cold forging, or the helical teeth may be formed by performing cold forging after hot forging. When forming only by the second cold forging, after the process No. 9, the rough outer peripheral surface W41 is finished by machining, the helical teeth are formed by cold forging, and then the helical teeth are finished by sizing. When forming helical teeth by cold forging after the third hot forging, first, a hot forging step is added after step No. 3 shown in FIG. 3 to form coarse helical teeth. Thereafter, sizing is performed to finish the helical teeth by cold forging after step No. 9.

The reduction driven gear structure of the present invention is configured as described above, and the operation of the fiber structure formed inside by forging will now be described. FIG. 7 shows a state in which forged lines are formed inside the shaft portion extending downward from the center of the disk-shaped member A.
FIG. 7 (a) schematically shows the state of forged lines in a conventional rolled rough material for comparison. A plurality of forging lines R are formed in parallel to the axial direction from the outer periphery to the shaft core, and the intervals are sparse. On the other hand, FIG. 5B schematically shows a state in which the shaft portion is reduced in diameter by forging and a forged line is formed inside. First, as shown in FIG. 2 (1), the shaft portion is reduced in diameter to the shaft portion W13 by hot extrusion. Next, the diameter is further reduced sequentially to a shaft portion W42, a shaft portion W62, and a shaft portion W83 by cold forging. As a result, as shown in FIG. 7B, a plurality of forged lines are formed in parallel from the outer periphery to the inner side in the axial direction, and the forged lines F1 are formed densely on the outer peripheral surface side. The forged streamline F2 becomes sparse as it goes to the core.
Thus, the outer spline teeth 4 are formed by cold forging in the process No. 9 of FIG. 6 (9) in the place where the forged streamline F1 on the outer peripheral side of the shaft portion is densely formed. At this time, the forging line F1 is densely formed in the tooth profile of the outer spline teeth 4 while being bent along the tooth profile. In this way, a fiber structure flow of the forging line is continuously formed inside the tooth profile of the outer spline teeth 4. Since the tooth profile is formed only by forging the outer spline teeth 4, the forged line is not cut as in machining, so that a gear with excellent durability on the tooth profile surface can be obtained.
On the other hand, also in the inner spline teeth 2 at the upper end of the shaft portion, the inner diameter portion is previously drilled by forging. First, as shown in FIG. 2 (1), the shaft portion is perforated from the inner diameter portion W21 to the inner diameter portion W31 by hot extrusion. As a result, a forged line is formed inside the inner diameter portion as described in the case of the shaft portion. In this way, the inner spline teeth 2 are formed by cold forging in the step No. 9 of FIG. At this time, forging lines are densely formed in the tooth profile of the inner spline teeth 4 while bending along the tooth profile. As a result, since the forging line is not cut, a gear having excellent durability of the tooth profile surface can be obtained even in the inner spline teeth 2.

  Since the inner and outer spline teeth are formed only by cold forging, the forging surface is not scraped off by machining such as shaving, broaching or hobbing, and the internal forging line is held as it is and the gear is The durability of can be improved. Therefore, the reduction driven gear structure of the present invention is not limited to the use of automobile transmissions, but can of course be applied to the use of various machine devices such as machine tools, cargo handling construction machines, and robots.

A disk member B shaft member 100 reduction driven gear structure 1 reduction driven tooth 2 inner spline teeth 3, 30 drive shaft 4 outer spline teeth 5 hole 11 drive pinion shaft 12 hypoid pinion gear 13 reduction drive tooth 14 differential device P upper Type Q Die W0, W1, W2, W3, W4, W5, W6, W7, W8, W9, W10 Coarse material W11 Convex part, W12 Discoid part, W13 Shaft part, D1 Small diameter part, D2 Large diameter part W21 Inner diameter Part, W22 dent, W23 outer burr W31 inner diameter part W41 rough outer peripheral surface, W42 shaft part, D3 small diameter part W51 inner diameter part, d1 inner diameter W61 inner diameter part, d2 inner diameter, W62 smaller diameter part, D4 small diameter part W71 inner diameter part, d3 inner diameter W81 Inner Diameter, W82 Inner Diameter, W83 Shaft, D5 Small Diameter Part d4 Inner Diameter, d5 Inner Diameter

Claims (4)

A disk-shaped member and a shaft-shaped member coaxial with the disk-shaped member are provided integrally, and a hole penetrates the shaft in the vertical direction,
Helical teeth are provided on the outer peripheral surface of the disk-shaped member,
A reduction driven gear structure in which inner spline teeth are provided on the upper inner periphery of the hole, and outer spline teeth are provided on an outer peripheral surface below the shaft member.   The reduction driven gear structure according to claim 1, wherein the helical teeth are formed by forging.   The reduction driven gear structure according to claim 1, wherein the helical teeth are formed by machining. Forged streamlines by hot forging are formed in the vicinity of the outer peripheral surface of the shaft member, and outer spline teeth are formed by cold forging on the outer periphery,
The reduction driven gear structure according to claim 1, wherein a forged line formed by cold forging is formed on the outer spline teeth.

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